Note: Descriptions are shown in the official language in which they were submitted.
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CATALYST FOR THE PRODUCTION OF ETHANOL BY HYDROGENATION OF
ACETIC ACID
COMPRISING PLATINUM -TIN ON SILICACEOUS SUPPORT
Priority Claim
This application claims the priority of U.S. App. No 12/588,727, filed October
26, 2009, the entirety of which is incorporated herein by reference.
Field of the Invention
The present invention relates generally to a tunable catalyst for the
hydrogenation of carboxylic acids, particularly acetic acid and a flexible
process of
acetic acid dehydrogenation in which the proportion of ethanol relative to
ethyl
acetate and acetaldehyde may be varied with each catalyst change out to adapt
to
changing commercial conditions. More specifically, the present invention
relates to
a catalyst for gas phase hydrogenation of carboxylic acids, particularly
acetic acid to
produce a variety of products including the corresponding alcohols, esters and
aldehydes, especially ethanol. The catalysts exhibit excellent activity and
selectivity
over the range of products.
Background
There is a long felt need for an economically viable process to convert acetic
acid to ethanol which may be used in its own right or subsequently converted
to
ethylene which is an important commodity feedstock as it can be converted to
vinyl
acetate and/or ethyl acetate or any of a wide variety of other chemical
products.
For example, ethylene can also be converted to numerous polymer and monomer
products. Fluctuating natural gas and crude oil prices contribute to
fluctuations in
the cost of conventionally produced, petroleum or natural gas-sourced
ethylene,
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making the need for alternative sources of ethylene all the greater when oil
prices
rise.
Catalytic processes for reduction of alkanoic acids and other carbonyl group
containing compounds have been widely studied and a variety of combinations of
catalysts, supports and operating conditions have been mentioned in the
literature.
Reduction of various carboxylic acids over metal oxides is reviewed by T.
Yokoyama
et al. in "Fine chemicals through heterogeneous catalysis. Carboxylic acids
and
derivatives." Chapter 8.3.1, summarizes some of the developmental efforts for
hydrogenation catalysts for various carboxylic acids. (Yokoyama, T.; Setoyama,
T.
"Carboxylic acids and derivatives." in: "Fine chemicals through heterogeneous
catalysis." 2001, 370-379.)
A series of studies by M. A. Vannice et al. concern conversion of acetic acid
over a variety of heterogeneous catalysts (Rachmady W.; Vannice, M. A.; J.
Catal.
2002, 207, 317-330.)
Vapor-phase reduction of acetic acid by H2 over both supported and
unsupported iron was reported in separate study. (Rachmady, W.; Vannice, M. A.
J.Catal. 2002, 208,158-169.)
Further information on catalyst surface species and organic intermediates is
set forth in Rachmady, W.; Vannice, M. A., J. Catal. 2002, 208,170-179.
Vapor-phase acetic acid hydrogenation was studied further over a family of
supported Pt-Fe catalysts in Rachmady, W.; Vannice, M. A. J. Catal. 2002, 209,
87-98
and Rachmady, W.; Vannice, M. A. J. Catal. 2000,192, 322-334.
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Various related publications concerning the selective hydrogenation of
unsaturated aldehydes may be found in (Djerboua, F.; Benachour, D.; Touroude,
R.
Applied Catalysis A: General 2005, 282, 123-133.; Liberkova, K.; Tourounde,
R.J. Mol.
Catal. 2002, 180,221-230.; Rodrigues, E. L.; Bueno, J. M. C. Applied Catalysis
A:
General 2004, 257, 210-211.; Ammari, F.; Lamotte, J.; Touroude, R. J. Catal.
2004,221,32-42; Ammari, F.; Milone, C.; Touroude, R. J. Catal. 2005,235, 1-9.;
Consonni, M.; Jokic, D.; Murzin, D. Y.; Touroude, R.J. Catal. 1999, 188, 165-
175.;
Nitta, Y.; Ueno, K.; Imanaka, T.; Applied Catal. 1989, 56, 9-22. )
Studies reporting activity and selectivity over cobalt, platinum and tin -
containing catalysts in the selective hydrogenation of crotonaldehyde to the
unsaturated alcohol are found in R. Touroude et al. (Djerboua, F.; Benachour,
D.;
Touroude, R. Applied Catalysis A: General 2005, 282, 123-133 as well as
Liberkova,
K.; Tourounde, R.; J. Mal. Catal. 2002, 180, 221-230) as well as K. Lazar et
at. (Lazar,
K.; Rhodes, W. D.; Borbath, I.; Hegedues, M.; Margitfalvi, 1. L. Hyperfine
Interactions
2002, 1391140, 87-96.)
M. Santiago et at. (Santiago, M. A. N.; Sanchez-Castillo, M. A.; Cortright, R.
D.;
Dumesic, 1. A. J. Catal. 2000, 193, 16-28.) idiscuss microcalorimetric,
infrared
spectroscopic, and reaction kinetics measurements combined with quantum-
chemical calculations.
Catalytic activity in for the acetic acid hydrogenation has also been reported
for heterogeneous systems with Rhenium and Ruthenium. (Ryashentseva, M. A.;
Minachev, K. M.; Buiychev, B. M.; Ishchenko, V. M. Bull. Acad Sci. USSR1988,
2436-
2439).
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United States Patent No. 5,149,680 to Kitson et al. describes a process for
the
catalytic hydrogenation of carboxylic acids and their anhydrides to alcohols
and/or
esters utilizing platinum group metal alloy catalysts. United States Patent
No.
4,777,303 to Kitson et al. describes a process for the productions of alcohols
by the
hydrogenation of carboxylic acids. United States Patent No. 4,804,791 to
Kitson et al.
describes another process for the production of alcohols by the hydrogenation
of
carboxylic acids. See also USP 5,061,671; USP 4, 990, 655; USP 4,985,572; and
USP
4,826,795.):
Malinowski et al. (Bull. Soc. Chim. BeIg. (1985), 94(2), 93-5,) discuss
reaction
catalysis of acetic acid on low-valent titanium heterogenized on support
materials
such as silica (SiO2) or titania (Ti02).
Bimetallic ruthenium-tin/silica catalysts have been prepared by reaction of
tetrabutyl tin with ruthenium dioxide supported on silica. (Loessard et al.,
Studies in
Surface Science and Catalysis (1989), Volume Date 1988, 48 (Struct. React.
Surf.),
591-600.)
The catalytic reduction of acetic acid has also been studied in, for instance,
Hindermann et al., (Hindermann et al., J. Chem. Res., Synopses (1980), (11),
373),
dsiclosing catalytic reduction of acetic acid on iron and on alkali-promoted
iron.
Existing processes suffer from a variety of issues impeding commercial
viability including: (i) catalysts without requisite selectivity to ethanol;
(ii) catalysts
which are possibly prohibitively expensive and/or nonselective for the
formation of
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ethanol and produces undesirable by-products; (iii) operating temperatures and
pressures which are excessive; and/or (iv) insufficient catalyst life.
Summary of the Invention
We have found that when reducing acetic acid over a platinum tin catalyst
dispersed on a modified stabilized silicaceous support including an effective
amount
of a support modifier selected from the group consisting of: (i) alkaline
earth oxides,
(ii) alkali metal oxides, (iii) alkaline earth metasilicates, (iv) alkali
metal metasilicates,
(v) zinc oxide , (vi) zinc metasilicate and (vii) precursors for any of (i)-
(vi), and
mixtures of any of (i)-(vii) by passing a gaseous stream comprising hydrogen
and
acetic acid in the vapor phase in a mole ratio of hydrogen to acetic acid of
at least
about 4:1 at a temperature of between about 125 C and 350 C, more preferably
between about 225 and 300 C, still more preferably between about 250 C and
300 C over that catalyst, we can obtain high selectivity in conversion to
ethanol
when the amounts and oxidation states of the platinum and tin, as well as the
ratio
of platinum to tin and the modified stabilized silicaceous support are
controlled as
described herein. In one aspect of the invention, we counteract the effect of
Bronsted acid sites present on the surface of the silicaceous support with a
support
modifier selected as described above. In another aspect, the above described
support modifiers are effective to prevent excessive loss of activity and
selectivity by
the catalyst over periods of up to 168, 336 or even 500 hours at 275 C in the
presence of flowing acetic acid vapor. In another aspect of the invention, the
support modifier is effective to suppress production of ethyl acetate
resulting in high
selectivity to ethanol production when desired accompanied by low selectivity
toward conversion of acetic acid to highly undesirable by-products such as
alkanes.
Preferably, the support modifier is chosen from the group consisting of oxides
and
metasilicates of sodium, potassium, magnesium, calcium, and zinc as well as
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precursors therefor and mixtures of any of the foregoing. The most preferred
support modifier is calcium metasilicate.
We have found that when reducing acetic acid over a platinum tin catalyst
dispersed on an essentially basic calcium metasilicate/silica support by
passing a
gaseous stream comprising hydrogen and acetic acid in the vapor phase in a
mole
ratio of hydrogen to acetic acid of at least about 4:1 at a temperature of
between
about 125 C and 350 C , more preferably between about 225 and 300 C, still
more
preferably between about 250 C and 300 C over that catalyst, we can obtain
high
selectivity in conversion to ethanol when the amounts and oxidation states of
the
platinum and tin, as well as the ratio of platinum to tin and the acidity of
the calcium
metasilicate/silica support are controlled as described herein. In particular,
using
preferred catalysts and processes of the present invention at least 80% of the
acetic
acid converted is converted to ethanol and less than 4% of the acetic acid is
converted to compounds other than compounds chosen from the group consisting
of ethanol, acetaldehyde, ethyl acetate, ethylene and mixtures thereof. In
preferred
processes, platinum is present in an amount of 0.5 % to 5% of the weight of
the
catalyst; while tin is present in an amount of from at least 0.5 up to 10% by
weight of
the catalyst; preferably, the surface area of the support is at least about
100 m2/g,
more preferably about 150 m2/g, still more preferably at least about 200 m2/g,
most
preferably at least about 250 m2/g; the mole ratio of tin to platinum group
metal is
preferably from about 1:2 to about 2:1, more preferably from about 2:3 to
about
3:2; still more preferably from about 5:4 to about 4:5; most preferably from
about
9:10 to 10:9. In many cases the support comprises calcium silicate in an
amount
effective to balance Bronsted acid sites resulting from residual alumina in
the silica;
typically from about 1% up to about 10% by weight of calcium silicate is
sufficient to
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ensure that the support is essentially neutral or basic in character. In one
particularly
preferred embodiment, platinum is present in the hydrogenation catalyst in an
amount of at least about 0.75%, more preferably 1% by weight; the mole ratio
of tin
to platinum is from about 5:4 to about 4:5; and the support comprises from at
least
about 2.5% to about 10% by weight of calcium silicate.
One aspect of many embodiments of the present invention is that space
velocities of over about 1000 hr 1, 2500 hr -1 and even over 5000 hr-'can be
used
while at least 90% of the acetic acid converted is converted to ethanol and
less than
2% of the acetic acid is converted to compounds other than compounds chosen
from the group consisting of ethanol, acetaldehyde, ethyl acetate, and
ethylene and
mixtures thereof. In many embodiments of the present invention, formation of
alkanes is low, usually under 2%, often under 1%, and in many cases under 0.5%
of
the acetic acid passed over the catalyst is converted to alkanes having little
value
other than as fuel or synthesis gas.
In another aspect of this invention, alkanoic acids are hydrogenated by
passing a gaseous stream comprising hydrogen and the alkanoic acid in the
vapor
phase in a mole ratio of hydrogen to alkanoic acid of at least about 2:1 at a
temperature of between about 125 C and 350 C over a hydrogenation catalyst
comprising: a platinum group metal chosen from the group consisting of
platinum,
palladium and mixtures thereof on a silicaceous support chosen from the group
consisting of silica, calcium metasilicate and calcium metasilicate promoted
silica;
and a promoter chosen the group consisting of tin, rhenium and mixtures
thereof,
the silicaceous support being optionally promoted with a promoter chosen from
the
group consisting of: a promoter chosen from the group consisting of alkali
metals;
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alkaline earth elements and zinc in an amount of 1 to 5% by weight of the
catalyst; a
redox promoter chosen from the group consisting of: W03; MoO3; Fe203 and Cr203
in an amount of 1 to 50% by weight of the catalyst; and an acidic modifier
chosen
from the group consisting of Ti02; Zr02; Nb205; Ta205; and A1203 in an amount
of 1 to
50% by weight of the catalyst wherein the acidity of the support is controlled
such
that less than 4, preferably less than 2 and most preferably less than about
1% of the
alkanoic acid is converted to an alkane. In many cases, at least one of
platinum and
palladium is present in an amount of 0.25 % to 5% of the weight of the
catalyst; the
combined amount of platinum and palladium present is at least 0.5% by weight
of
catalyst; and the combined amount of rhenium and tin present is at least 0.5
to 10%
by weight. As with the catalysts comprising platinum and tin on a basic silica
support, in this process, the amounts and oxidation states of the platinum
group
metals, the rhenium and tin promoters, as well as the mole ratio of platinum
group
metal to combined moles of rhenium and tin present; and the acidity of the
silicaceous support are controlled such that at least 80% of the acetic acid
converted
is converted to a compound chosen from the group consisting of an alkanol and
alkyl
acetate while less than 4% of the alkanoic acid is converted to compounds
other
than compounds chosen from the group consisting of the corresponding alkanols,
alkyl acetates and mixtures thereof. Preferably, at least one of platinum and
palladium is present in an amount of 0.5 % to 5% of the weight of the
catalyst; the
combined amount of platinum and palladium present is at least 0.75% to 5% of
the
weight of the catalyst. Preferably, the alkanoic acid is acetic acid and the
combined
amount of tin and rhenium present is at least 1.0% by weight of catalyst while
the
amounts and oxidation states of the platinum group metals, the rhenium and tin
promoters, as well as the ratio of platinum group metal to rhenium and tin
promoters; and the acidity of the silicaceous support are controlled such that
at
least 80% of the acetic acid converted is converted to ethanol or ethyl
acetate and
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less than 4% of the acetic acid is converted to compounds other than compounds
chosen from the group consisting of ethanol, acetaldehyde, ethyl acetate,
ethylene
and mixtures thereof. Preferably, the combined weight of rhenium and tin
present
is from about 1 to 10% by weight of the catalyst while the mole ratio of
platinum
group metal to moles of rhenium and tin combined is from about 1:2 to about
2:1.
In another aspect, this invention relates to a process for hydrogenation of
acetic acid comprising passing a gaseous stream comprising hydrogen and acetic
acid in the vapor phase in a mole ratio of hydrogen to acetic acid of at least
about
4:1 at a temperature of between about 225 C and 300 C over a hydrogenation
catalyst consisting essentially of metallic components dispersed on an oxidic
support, said hydrogenation catalyst having the composition:
PtvPdwRexSnyCapSigOr,
wherein the ratio of v:y is between 3:2 and 2:3; and/or the ratio of w:x is
between
1:3 and 1:5, p and q are selected such that p:q is from 1:20 to 1:200 with r
being
selected to satisfy valence requirements and v and w being selected such that
0.005 < + ls7aw* < 0.0 S.
In this aspect, the process conditions and values of v, w, x, y, p, q, and r
are
preferably chosen such that at least 90% of the acetic acid converted is
converted to
a compound chosen from the group consisting of ethanol and ethyl acetate while
less than 4% of the acetic acid is converted to alkanes. In many embodiments
of the
present invention, p is selected, in view of any minor impurities present, to
ensure
that the surface of the support is essentially free of active Bronsted acid
sites.
Still another aspect of this invention relates to a process for production of
ethanol by reduction of acetic acid comprising passing a gaseous stream
comprising
hydrogen and acetic acid in the vapor phase in a mole ratio of hydrogen to
acetic
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acid of at least about 4:1 at a temperature of between about 225 C and NOT
over a
hydrogenation catalyst consisting essentially of metallic components dispersed
on
an oxidic support, said hydrogenation catalyst having the composition:
PtõPdwRexSnYAIZCapSigOr,
wherein v and y are between 3:2 and 2:3; w and x are between 1:3 and 1:5,
wherein p and z and the relative locations of aluminum and calcium atoms
present are controlled such that Bronsted acid sites present upon the surface
thereof are balanced by calcium silicate; p and q are selected such that p:q
is
from 1:20 to 1:200 with r being selected to satisfy valence requirements and
v and w are selected such that
0.005 <_ (125v + 1s75w < 0.05.
Preferably, in this aspect, the hydrogenation catalyst has a surface area of
at least
about 100 m2/g and z and p >_ z. In many embodiments of the present invention,
p is
selected, in view of any minor impurities present, to also ensure that the
surface of
the support is essentially free of active Bronsted acid sites which seem to
facilitate
conversion of ethanol into ethyl acetate.
Another aspect of this invention relates to a process for production of
ethanol and ethyl acetate by reduction of acetic acid comprising passing a
gaseous
stream comprising hydrogen and acetic acid in the vapor phase in a mole ratio
of
hydrogen to acetic acid of at least about 4:1 at a temperature of between
about
225 C and 300 C over a hydrogenation catalyst comprising: a platinum group
metal
chosen from the group consisting of platinum, and mixtures of platinum and
palladium on a silicaceous support chosen from the group consisting of silica,
and
silica promoted with up to about 7.5 calcium metasilicate, the amount of
platinum
group metal present being at least about 2.0%, the amount of platinum present
being at least about 1.5%; and a metallic promoter chosen from the group
consisting
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from the group consisting of rhenium and tin an amount of between about 1% and
2% by weight of the catalyst, the mole ratio of platinum to metallic promoter
being
between about 3:1 and 1:2; the silicaceous support being optionally promoted
with
a second promoter chosen from the group consisting of: a donor promoter chosen
from the group consisting of alkali metals; alkaline earth elements and zinc
in an
amount of 1 to 5% by weight of the catalyst; a redox promoter chosen from the
group consisting of: W03; MoO3; Fe2O3 and Cr2O3 in an amount of 1 to 50% by
weight of the catalyst; an acidic modifier chosen from the group consisting of
TiO2;
Zr02; Nb2O5; Ta205; and A1203 in an amount of 1 to 50% by weight of the
catalyst;
and combinations thereof.
In preferred aspects of this invention, the mole ratio of metallic promoter to
platinum group metal is from about 2:3 to about 3:2, more preferably about 5:4
to
about 4:5 and most preferably from about 9:10 to about 10:9 while the surface
area
of the silicaceous support is at least about 200 m2/g and the amount of sodium
silicate is sufficient to render the surface of the support essentially basic.
In some
cases, the use of calcium silicate can be controlled such that the mole number
of
Bronsted Acid sites present on the surface thereof is no more than the mole
number
of Bronsted Acid sites present on the surface of Saint-Gobain NorPro SS61138
silica:
in other cases, the silica used may be a high purity pyrogenic silica having a
low
content of alumina or other impurities. In many cases, such silicas will
comprise
over 99% silica, more preferably over 99.5% silica, most preferably over 99.7%
silica.
In many embodiments of the present invention, either by control of the purity
of the
silica or by balancing Bronsted acid sites present on the surface of the
support with
calcium silicate or one of the other suitable stabilizer modifiers discussed
herein, the
available mole number of Bronsted Acid sites present on the surface thereof is
no
more than the mole number of Bronsted Acid sites present on the surface of
Saint-
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Gobain NorPro SS61138 silica, preferably less than half, more preferably less
than
25% and still more preferably less than 10% of the mole number of Bronsted
Acid
sites present on the surface of Saint-Gobain NorPro SS61138 silica. The number
of
acid sites present on the surface of the support may be determined using
pyridine
titration following procedures described in:
(1) F. Delannay, Ed., "Characterization of Heterogeneous Catalysts"; Chapter
III: Measurement of Acidity of Surfaces, p. 370 - 404; Marcel Dekker, Inc., N.
Y. 1984.
(2) C. R. Brundle, C. A. Evans, Jr., S. Wilson, L. E. Fitzpatrick, Eds.,
"Encyclopedia of Materials Characterization"; Chapter 12.4: Physical and
Chemical Adsorption Measurements of Solid Surface Areas, p. 736-744;
Butterworth-Heinemann, MA 1992.
(3) G. A. Olah, G. K. Sura Prakask, Eds, "Superacids"; John Wiley & Sons, N.
Y.
1985.
Throughout this specification and claims, unless the context indicates
otherwise, when measuring the acidity of a surface or the number of acid sites
thereupon, the technique described in F. Delannay, Ed., "Characterization of
Heterogeneous Catalysts"; Chapter III: Measurement of Acidity of Surfaces, p.
370 -
404; Marcel Dekker, Inc., N. Y. 1984 should be used.
In the more preferred case, the surface area of the silicaceous support is at
least about 250 m2/g and the mole number of available Bronsted Acid sites
present
on the surface thereof is no more than one half the mole number of Bronsted
Acid
sites present on the surface of Saint-Gobain NorPro HSA 5561138 silica and the
hydrogenation will be conducted at a temperature of between about 250 C and
300 C.
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As will be appreciated by one of skill in the art reviewing the discussion
herein, catalyst supports other than silicaceous supports described above may
be
used in some embodiments provided that the components are selected such that
the catalyst system is suitably active, selective and robust under the process
conditions employed. Suitable supports may include stable metal oxide-based
supports or ceramic-based supports as well as molecular sieves, including
zeolites.
So also, in some embodiments, carbon supports may be used as described in the
aforementioned United States Patent No. 5,149,680 to Kitson et al. at Col. 2,
line
64-col 4, line 22, the disclosure of which is incorporated herein by
reference.
In cases where mixtures of ethanol and ethyl acetate are to be produced
simultaneously, in many embodiments of the present invention, the
hydrogenation
catalyst may comprise: palladium on a silicaceous support chosen from the
group
consisting of silica, and silica promoted with up to about 7.5 calcium
metasilicate,
the amount of palladium present being at least about 1.5%; while the metallic
promoter is rhenium in an amount of between about 1% and 10% by weight of the
catalyst, the mole ratio of rhenium to palladium being between about 4:1 and
1:4,
preferably 2:1 and 1:3.
In cases where it is desired to produce primarily ethanol, the catalyst, in
many embodiments of the present invention, may consist essentially of platinum
on
a silicaceous support consisting essentially of silica promoted with from
about 3 up
to about 7.5% calcium silicate, the amount of platinum present being at least
about
1.0%, and a tin promoter in an amount of between about 1% and 5% by weight of
the catalyst, the mole ratio of platinum to tin in many embodiments of the
present
invention being between about 9:10 and 10:9. In some cases, minor amounts of
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another platinum group metal may be included, most often palladium in the
catalytic metal of the formulation. In many embodiments of the present
invention,
the amount of platinum group metal present is at least about 2.0%, the amount
of
platinum present being at least about 1.5%, preferably between 2.5 and 3.5
weight
percent platinum and the tin promoter is present in an amount of between about
2% and 5% by weight of the catalyst, while the process is conducted at a
temperature of between about 2502C and 3002C at a GHSV of at least about 1000
hr -1 at a pressure of at least 2 atm. The ratio of tin to platinum is
preferably between
2:3 and 3:2, more preferably between 4:5 and 5:4 and most preferably between
9:10 and 10:9. In yet other embodiments in which it is desired to produce
primarily
ethanol, the catalyst may comprise platinum on a silicaceous support
consisting
essentially of silica promoted with from about 3 up to about 7.5% calcium
silicate,
the amount of platinum present being at least about 1.0%, and a tin promoter
in an
amount of between about 1% and 5% by weight of the catalyst, the mole ratio of
platinum to tin in many embodiments of the present invention being between
about
9:10 and 10:9.
Another aspect of the invention relates to a particulate catalyst for
hydrogenation of alkanoic acids to the corresponding alkanol, comprising: a
platinum group metal chosen from the group consisting of platinum, palladium
and
mixtures thereof on a silicaceous support chosen from the group consisting of
silica,
and silica promoted with from about 3.0 up to about 7.5 calcium metasilicate,
the
surface area of the silicaceous support being at least about 150 m2/g; and a
tin
promoter in an amount of between about 1% and 3% by weight of the catalyst,
the
mole ratio of platinum to tin being between about 4:3 and 3:4; the composition
and
structure of the silicaceous support being chosen such that the surface
thereof is
essentially basic.
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Another aspect of this invention relates to a particulate hydrogenation
catalyst consisting essentially of: a silicaceous support having dispersed
thereupon a
platinum group metal chosen the group consisting of platinum, palladium, and
mixtures thereof with a promoter chosen from the group consisting of tin,
cobalt
and rhenium, the silicaceous support having a surface area of at least about
175
m2/g and being chosen from the group consisting of silica, calcium
metasilicate and
calcium metasilicate promoted silica having calcium metasilicate being
disposed on
the surface thereof, the surface of the silicaceous support being essentially
free of
Bronsted acid sites due to alumina unbalanced by calcium. In those variants
best
suited for production of ethanol and ethyl acetate simultaneously, the total
weight
of platinum group metals present is between 0.5% and 2%, the amount of
palladium
present is at least 0.5%, the promoter is rhenium, the weight ratio of rhenium
to
palladium being between 10:1 and 2:1, and the amount of calcium meta-silicate
is
between 3 and 90%.
In those aspects best suited for production of ethanol at high selectivity,
the
total weight of platinum group metals present is between 0.5 and 2%, the
amount of
platinum present is at least 0.5 %, the promoter is cobalt, the weight ratio
of cobalt
to platinum being between 20:1 and 3:1, and the amount of calcium silicate is
between 3 and 90%, while for production of ethanol with a catalyst having
extended
life, the hydrogenation catalyst comprises between 2.5 and 3.5 weight percent
platinum, between 3 weight % and 5 weight % tin dispersed on high surface area
pyrogenicly derived silica having a surface area of at least 200 mZ per gram,
said
high surface area silica being promoted with an effective amount of calcium
metasilicate to ensure that the surface thereof is essentially free of
Bronsted acid
sites unbalanced by calcium metasilicate, the molar ratio of platinum to tin
being
between 4:5 and 5:4.
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In another catalyst of the present invention, the total weight of platinum
group metal present is between 0.5 and 2%, the amount of palladium present is
at
least 0.5%, the promoter is cobalt, the weight ratio of cobalt to palladium
being
between 20:1 and 3:1, and the amount of calcium silicate is between 3 and 90%.
Still another catalyst of the present invention is a hydrogenation catalyst
comprising: between 0.5 and 2.5 weight percent palladium, between 2 weight %
and
7 weight % rhenium, the weight ratio of rhenium to palladium being at least
1.5:1.0,
the rhenium and palladium being dispersed on a silicaceous support, said
silicaceous
support comprising at least 80% calcium metasilicate.
We have found that surprisingly high activity and life combined with
excellent selectivity for hydrogenation of acetic acid to ethanol are obtained
from
catalysts chosen the group consisting of:
(i ) catalysts combining a platinum group metal chosen the group consisting
of platinum, palladium, and mixtures thereof with tin or rhenium on a
silicaceous support chosen from the group consisting of silica, calcium
metasilicate and calcium metasilicate promoted silica;
(ii) catalysts combining palladium and rhenium supported on a silicaceous
support comprising chosen from the group consisting of silica, calcium
metasilicate and calcium metasilicate promoted silica, the silicaceous
support being optionally promoted with 1% to 5% of a promoter chosen
group consisting of: alkali metals; alkaline earth elements and zinc,
promoter being preferably added to the catalyst formulation in the form
of the respective nitrates or acetates, of the these promoters,
particularly preferred are potassium, cesium, calcium, magnesium and
zinc;
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(iii) platinum promoted with cobalt on a high surface area silicaceous support
chosen from the group consisting of silica, calcium metasilicate and
calcium metasilicate promoted silica; and
(iv) palladium promoted with cobalt on a high surface area silicaceous
support chosen from the group consisting of silica, calcium metasilicate
and calcium metasilicate promoted silica.
Another aspect of the present invention concerns a process for
hydrogenating alkanoic acids comprising passing a gaseous stream comprising
hydrogen and an alkanoic acid in the vapor phase in a mole ratio of hydrogen
to
alkanoic acid of at least about 2:1 at a temperature of between about 125 C
and
350 C over a hydrogenation catalyst comprising:
a. a platinum group metal chosen from the group consisting of
platinum, palladium and mixtures thereof on a silicaceous support
chosen from the group consisting of silica, calcium metasilicate
and calcium metasilicate promoted silica; and
b. a promoter chosen the group consisting of tin and rhenium,
c. the silicaceous support being optionally promoted with a
promoter chosen from the group consisting of :
i. a promoter chosen from the group consisting of alkali
metals; alkaline earth elements and zinc in an amount of
1 to 5% by weight of the catalyst;
ii. a redox promoter chosen from the group consisting of :
W03; MoO3; Fe2O3 and Cr2O3 in an amount of 1 to 50% by
weight of the catalyst; and
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iii. an acidic modifier chosen from the group consisting of
Ti02; ZrO2; Nb205; Ta205; and AI2O3 in an amount of 1 to
50% by weight of the catalyst.
Preferably, the alkanoic acid is acetic acid, and platinum, if present, is
present in an amount of 0.5 % to 5% of the weight of the catalyst; palladium,
if
present, is present in an amount of 0.25% to 5% of the weight of the catalyst;
the
combined amount of platinum and palladium present is at least 0.5% by weight
of
catalyst; and tin is present in an amount of at least 0.5 to 5% with the ratio
of
platinum to tin being as previously described.
In another aspect of the invention, the surface area of the silicaceous
support is at least about 150 m2/g, more preferably at least about 200 m2/g'
and
most preferably at least about 250 m2/g. in more preferred embodiments, the
silicaceous support comprises up to about 7.5% calcium metasilicate. In other
embodiments the silicaceous support comprises up to about 90% calcium
metasilicate. In all embodiments, control of the acidity of the support can be
quite
beneficial, particularly when substantially pure ethanol is to be produced. In
the
case where silica alone is used as the support, it is quite beneficial to
ensure that the
amount of alumina, which is a common contaminant for silica, is low,
preferably
under 1%; more preferably under 0.5%; most preferably under 0.3% by weight. In
this regard, so-called pyrogenic silica is greatly preferred as it commonly is
available
in purities exceeding 99.7%. In this application, when we mention high purity
silica,
we are referring to silica wherein acidic contaminants such as alumina are
present at
levels of less than 0.3% by weight. In the cases where calcium metasilicate
promoted silica is used, it is not normally necessary to be quite as strict
about the
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purity of the silica used as the support although alumina is undesirable and
will not
normally be added intentionally.
In more preferred embodiments of the present invention, platinum, if
present, is present in an amount of 1 % to 5% of the weight of the catalyst;
palladium, if present, is present in an amount of 0.5% to 5% of the weight of
the
catalyst; and the combined amount of platinum and palladium present is at
least 1%
by weight of the catalyst.
In another preferred embodiment of the present invention where the support
is essentially pure high surface area silica , preferably pyrogenically formed
silica, tin
is present in amount of 1% to 3% by weight of the catalyst and, more
preferably, the
mole ratio of tin to platinum group metal is from about 1: 2 to about 2:1;
still more
preferably the mole ratio of tin to platinum is from about 2:3 to about 3:2;
while
most preferably the mole ratio of tin to platinum is from about 5:4 to about
4:5. In
cases where the support also comprises a minor amount of CaSiO3 or other
stabilizer
modifiers in the range of from about 2% to about 10%, larger amount of acidic
impurities can be tolerated so long as they are counter-balanced by an
appropriate
amount of an essentially basic stabilizer modifier.
In another aspect of the present invention, the process is preferably carried
out at a temperature of between about 225 C and 300 C, more preferably between
250 C and 300 C wherein said hydrogenation catalyst comprises: a platinum
group
metal chosen from the group consisting of platinum, and mixtures of platinum
and
palladium on a silicaceous support chosen from the group consisting of silica,
and
silica promoted with up to about 7.5 calcium metasilicate, the amount of
platinum
group metal present being at least about 2.0%, the amount of platinum present
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being at least about 1.5%; and a tin promoter in an amount of between about 1%
and 2% by weight of the catalyst, the mole ratio of platinum to tin being
between
about 3:1 and 1:2, the silicaceous support being optionally promoted with a
promoter chosen from the group consisting of : a promoter chosen from the
group
consisting of alkali metals; alkaline earth elements and zinc in an amount of
1 to 5%
by weight of the catalyst; a redox promoter chosen from the group consisting
of:
W03; MoO3; Fe2O3 and Cr2O3 in an amount of 1 to 50% by weight of the catalyst;
and
an acidic modifier chosen from the group consisting of Ti02; ZrO2; Nb2O5;
Ta205; and
A12O3 in an amount of 1 to 50% by weight of the catalyst.
In a particularly preferred process of the present invention for hydrogenating
alkanoic acids, the catalyst comprises: a platinum group metal chosen from the
group consisting of platinum, palladium and mixtures thereof on a silicaceous
support chosen from the group consisting of high surface area high purity
silica, and
high surface area silica promoted with up to about 7.5 calcium metasilicate,
the
amount of platinum group metal present being at least about 2.0%, the amount
of
platinum present being at least about 1.5%,; and the amount of tin promoter is
between about 1% and 5% by weight of the catalyst, the mole ratio of platinum
to
tin being between about 3:2 and 2:3. Preferably, the high purity silica is
pyrogenically generated, then tableted or pelleted into a form dense enough
for use
in a fixed bed catalyst. However, even in the case of high purity silica,
presence of a
stabilizer modifier, particularly calcium silicate, appears to extend, or
stabilize, the
activity and selectivity of the catalyst for prolonged periods extending into
weeks,
and even months, of commercially viable operation in the presence of acetic
acid
vapor at temperatures around 275 C at space velocities of 2500hr 1 and higher.
In
particular, it is possible to achieve such a degree of stability that catalyst
activity will
decline by less than 10% over periods of a week (168 hours) or two (336 hours)
or
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even over 500 hours. Accordingly, it can be appreciated that the catalysts of
the
present invention are fully capable of being used in commercial scale
industrial
applications for hydrogenation of acetic acid, particularly in production of
high
purity ethanol as well as mixtures of ethyl acetate and ethanol.
Another aspect of the invention relates to hydrogenation catalysts based on
group VIII metals (Fe, Co, Ni, Ru, Rh, Pd, Ir, Pt and Os) or other transition
metals
(notably Ti, Zn, Cr, Mo and W) on oxidic supports incorporating basic non-
volatile
stabilizer-modifiers on the surface of or into the support itself in the form
of oxides
and metasilicates of alkaline earth metals, alkali metals, zinc, scandium,
yttrium,
precursors for the oxides and metasilicates, as well as mixtures thereof in
amounts
sufficient to: counteract acidic sites present on the surface thereof; impart
resistance to shape change (primarily due to inter alia sintering, grain
growth, grain
boundary migration, migration of defects and dislocations, plastic deformation
and/or other temperature induced changes in microstructure) at temperatures
encountered in hydrogenation of acetic acid; or both.
In another embodiment of the process of the present invention, the catalyst
is chosen from:
(i ) catalysts combining a platinum group metal chosen the group
consisting of platinum, palladium, and mixtures thereof with tin or
rhenium on a silicaceous support chosen from the group
consisting of silica, calcium metasilicate and silica stabilized with
and modified by calcium metasilicate;
(ii) catalysts combining palladium and rhenium supported on a
silicaceous support comprising chosen from the group consisting
of, calcium metasilicate and calcium metasilicate promoted silica,
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the silicaceous support being optionally promoted with one to 5%
of a promoter chosen group consisting of: alkali metals; alkaline
earth elements and zinc;
(iii) platinum promoted with cobalt on a silicaceous support chosen
from the group consisting of silica, calcium metasilicate and
calcium metasilicate promoted silica; and
(iv) palladium promoted with cobalt on a silicaceous support chosen
from the group consisting of silica, calcium metasilicate and
calcium metasilicate promoted silica.
In general, the silicaceous support incorporates a promoter chosen from the
group consisting of: stabilizer-modifiers comprising oxides and metasilicate
of alkali
metals; alkaline earth elements and zinc and precursors therefor in an amount
of
1 to 5% by weight of the catalyst; a redox promoter chosen from the group
consisting of: W03; MoO3; Fe203 and Cr203 in an amount of 1 to 50% by weight
of
the catalyst; and an acidic modifier chosen from the group consisting of Ti02;
Zr02;
Nb205; Ta205; and A1203 in an amount of 1 to 50% by weight of the catalyst,
the
presence of an acidic modifier favoring production of ethyl acetate in
combination
with ethanol.
Another aspect of the present invention relates to a particulate catalyst for
hydrogenation of alkanoic acids to the corresponding alkanol, comprising: a
platinum group metal chosen from the group consisting of platinum, palladium
and
mixtures thereof on a silicaceous support chosen from the group consisting of
silica,
silica promoted with up to about 7.5 calcium metasilicate and mixtures
thereof, the
surface area of the silicaceous support being at least about 150 m2/g; and a
tin
promoter in an amount of between about 1% and 2% by weight of the catalyst,
the
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mole ratio of platinum to tin being between about 3:2 and 3:2, the silicaceous
support being optionally promoted with a promoter chosen from the group
consisting of: an promoter chosen from the group consisting of alkali metals;
alkaline earth elements and zinc in an amount of 1 to 5% by weight of the
catalyst; a
redox promoter chosen from the group consisting of: W03; MoO3; Fe2O3 and Cr2O3
in an amount of 1 to 50% by weight of the catalyst; and an acidic modifier
chosen
from the group consisting of Ti02; ZrO2; Nb2O5; Ta205; and A12O3 in an amount
of 1 to
50% by weight of the catalyst.
An alternative embodiment of the present invention relates to a particulate
hydrogenation catalyst consisting essentially of: a silicaceous support having
dispersed thereupon a platinum group metal chosen the group consisting of
platinum, palladium, and mixtures thereof with a promoter chosen from the
group
consisting of tin, cobalt and rhenium, the silicaceous support having a
surface area
of at least about 175 m2/g and being chosen from the group consisting of
silica,
calcium metasilicate and calcium metasilicate promoted silica; the silicaceous
support being optionally promoted with: 1% to 5% of a promoter chosen group
consisting of alkali metals; alkaline earth elements and zinc in an amount of
1 to 5%
by weight of the catalyst; a redox promoter chosen from the group consisting
of :
W03i MoO3; Fe2O3 and Cr2O3 in an amount of 1 to 50% by weight of the catalyst;
and
an acidic modifier chosen from the group consisting of TiO2; Zr02; Nb2O5;
Ta205i and
A12O3 in an amount of 1 to 50% by weight of the catalyst. In one more
preferred
embodiment of the present invention, the total weight of platinum group metals
present is between 2 and 4%, the amount of platinum present is at least 2%,
the
promoter is tin, the mole ratio of platinum to tin being between 2:3 and 3:2,
and the
amount of calcium metasilicate is between 3 and 7%. In another more preferred
embodiment of the present invention, the total weight of platinum group metals
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present is between 0.5 % and 2%, the amount of palladium present is at least
0.5%,
the promoter is rhenium, the weight ratio of rhenium to palladium being
between
10:1 and 2: 1, and the amount of calcium metasilicate is between 3 and 90%. In
a
third more preferred embodiment of the present invention, the total weight of
platinum group metals present is between 0.5 and 2%, the amount of platinum
present is at least 0.5 %, the promoter is cobalt, the weight ratio of cobalt
to
platinum being between 20:1 and 3:1, and the amount of calcium silicate is
between
3 and 90 %. In a fourth more preferred embodiment of the present invention,
the
total weight of platinum group metals present is between 0.5 and 2%, the
amount of
palladium present is at least 0.5%, the promoter is cobalt, with the weight
ratio of
cobalt to palladium being between 20:1 and 3:1, and the amount of calcium
silicate
between 3 and 90%.
Brief Description of Drawings
The invention is described in detail below with reference to the appended
drawings, wherein like numerals designate similar parts. In the drawings:
Figures 1 and 2 illustrate the selectivity and productivity performance of
catalysts of
the present invention.
Figures 3A - 3C illustrate the relative temperature insensitivity of the
selectivity and
productivity of catalysts of the present invention al9ong with the variation
in
properties obtained when acetic acid is hydrogenated at 225 C over catalyst
activated at 225 C.
Figures 4A-4C illustrate the variations in selectivity, conversion and
productivity
incumbent upon changes in the ratio of platinum to tin the preferred platinum
tin
catalysts of the present invention.
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Figures SA and 5B illustrate the selectivity of the most preferred catalysts
the
present invention supported on high surface area silica for ethanol production
as
well as the high productivity obtained therewith.
Figures 6A and 6B, and Figures 7A and 7B illustrate the excellent selectivity
obtained
at low temperature using the most preferred catalysts the present invention
based
on calcium metasilicate promoted high surface area silica. It can be
appreciated
that the selectivity for ethanol is high.
Figures 8, 9, and 10 illustrate the effect of the mass fraction of rhenium on
hydrogenation of acetic acid using a palladium rhenium on silica catalyst of
the
present invention.
Figures 11 and 12 illustrate the performance of a platinum and cobalt catalyst
supported on silica.
Detailed Description of the Invention
Even though market conditions constantly fluctuate, for large scale
operations, the selectivities, activities and catalyst life reported in the
literature for
catalytic hydrogenation of acetic acid to ethanol imply economics generally
unfavorable to those needed to compete with other methods of ethanol
production.
One estimate of productivity needed for commercial viability has concluded
that
selectivity for ethanol in excess of about 50% with a productivity of about
200 g of
ethanol per kg of catalyst per hour would be needed. The catalysts of the
present
invention far exceed those requirements.
In the following description, all numbers disclosed herein are approximate
values, regardless whether the word "about" or "approximate" is used in
connection
therewith. They may vary by 1 percent, 2 percent, 5 percent, or, sometimes, 10
to
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20 percent. Whenever a numerical range with a lower limit, RL and an upper
limit,
Ru, is disclosed, any number falling within the range as well as any sub-range
is
specifically disclosed. In particular, the following numbers within the range
are
specifically disclosed: R=RL+k*(Ru-RL), wherein k is a variable ranging from 1
percent
to 100 percent with a 1 percent increment, i.e., k is 1 percent, 2 percent, 3
percent,
4 percent, 5 percent, ... , 50 percent, 51 percent, 52 percent, . . ., 95
percent, 96
percent, 97 percent, 98 percent, 99 percent, or 100 percent. Moreover, any
numerical range defined by two R numbers as defined in the above is also
specifically disclosed.
Figures 1 and 2 illustrate the selectivity and productivity performance of
catalysts of the present invention, graphically presenting the greatly
improved
selectivity and productivity attainable with these catalysts at a variety of
operation
temperatures. Notably, at 280 C and 296 C, the selectivity for ethanol is
about 60%.
In evaluating this, it is important to recall that ethyl acetate is also a
commodity of
considerable economic importance and value so that, even if the primary goal
is
production of ethanol, any acetic acid converted to ethyl acetate retains
considerable value, whereas any alkanes produced as by-products are generally
much lower in value than the feedstock. In Figure 1, productivity in terms of
grams
of ethanol produced per kilogram of catalyst per hour onstream are represented
as
a function of time (in hours) by squares, while productivity of ethyl acetate
is
represented by circles, and the productivity of acetaldehyde is represented by
diamonds. Significantly during this run, the operating temperature was
increased as
indicated during the run to demonstrate the effect of operating temperature
upon
productivity and selectivity. In Figure 2, the selectivity for ethanol as
hereinafter
defined is represented by circles as a function of time onstream while the
selectivity
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WO 2011/056595 PCT/US2010/054134
for ethyl acetate as hereinafter defined is represented by squares and the
selectivity
for acetaldehyde by diamonds.
Figures 3A -3C illustrate the relative temperature insensitivity of the
selectivity of catalysts of the present invention to the temperature at which
the
metal precursors are reduced. This characteristic is significant to commercial
viability
as it is possible to conduct the reaction in a vessel which is not specially
configured
to maintain uniform temperature throughout, typically these vessels are
referred to
as "adiabatic reactors" as there is little provision made for accommodating
the
temperature changes accompanying the reaction process although it is common to
"dilute" the catalyst with quartz chips or other inert particles to moderate
the
reaction. Figure 3A, reports the results of an experiment in which catalyst
was
reduced at the temperatures indicated in C and hydrogen and acetic acid
thereafter
hydrogenated over that catalyst at 250 C. The upper line indicates the
selectivity of
that particular catalyst for ethanol while the lower line represents the
selectivity for
ethyl acetate. In Figure 3B, the productivity results for that experiment are
presented in which the upper line reports the productivity of ethanol and the
lower
line the productivity of ethyl acetate. In Figure 3C, the conversion (as
hereinafter
defined) results for that experiment are presented as a function of reduction
temperature. In addition, acetic acid was also hydrogenated at a temperature
of
225 C. over the catalyst reduced or activated at 225 C. Points on Figure 3B
and 3C
are also included present results of that experiment in which acetic acid was
hydrogenated at 225 C. over the catalyst reduced at 225 C. It can be
appreciated
that hydrogenation over this catalyst at a temperature of 225 C. results in
decreased selectivity to ethanol and decreased conversion.
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Figures 4A-4C illustrate the variations in selectivity, conversion and
productivity incumbent upon changes in the ratio of platinum to tin in the
preferred
platinum tin catalysts of the present invention in correlation with the mol
fraction of
Pt in SiO2-Pt,,Sn(1_,) (E [Pt] +[Sn] = 1.20 mmol) in the catalytic
hydrogenation of acetic
acid using 2.5 mt solid catalyst (14/30 mesh, diluted 1:1 (v/v, with quartz
chips,
14/30 mesh); at an operating pressure p = 200 psig (14 bar); feed rates of
acetic
acid, hydrogen and nitrogen diluents of 0.09 g/min HOAc; 160 sccm/min 1-12;
and 60
sccm/min N2 respectively; the overall space velocity, GHSV, being 6570 h-'
overl2 h
of reaction time. It can be appreciated that, in this ezperiment, selectivity
to
production of ethanol is maximized at a mole ratio of about 1 to 1 for those
catalysts
supported on essentially pure high surface area silica. (Throughout this
specification, lower case script "e" is used for liter to avoid the ambiguity
resulting
from the similarity or even identity of the symbols used for the numeral one
and the
lower case twelfth letter of the Roman alphabet in many typefaces.) On each of
Figures 4A-4C, X;(Pt) on the horizontal access axis represents the mass
fraction of
platinum in the catalyst ranging between zero and one while selectivity,
conversion
and productivity are as indicated previously with Figure 4A representing the
selectivity of the catalyst toward ethanol and ethyl acetate, with the
selectivity for
ethanol peaking at a mass fraction of 50% where, as shown in Figure 4B, the
conversion of acetic acid also peaks as does the productivity of ethanol as
shown in
Figure 4C.
Figures 5A and B illustrate the selectivity and productivity of the most
preferred catalysts the present invention supported on high surface area
silica for
ethanol production as well as the high productivity obtained therewith. In
Figure 5A,
productivity in grams per kilogram of catalyst per hour onstream are indicated
on
the vertical axis wherein productivity for ethanol is represented by squares,
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productivity of ethyl acetate is represented by circles and productivity of
acetaldehyde is represented by diamonds. Similarly in Figure 513, selectivity
as
hereinafter defined is presented on the vertical axis as a function of time
onstream
in hours on the horizontal axis with selectivity to ethyl acetate again being
in
represented by circles, selectivity to ethanol being represented by squares
and
selectivity to acetaldehyde being represented by diamonds.
Figures 6 A and B, and Figures 7A and B illustrate the selectivity obtained at
low temperature using a preferred catalyst the present invention based on
calcium
metasilicate promoted high surface area silica using the same format as
Figures 5A
and B. It can be appreciated that the selectivity for ethanol is over 90%
throughout
the run.
Figures 8-12 are discussed in connection with the relevant examples.
The invention is described in detail below with reference to numerous
embodiments for purposes of exemplification and illustration only.
Modifications to
particular embodiments within the spirit and scope of the present invention,
set
forth in the appended claims, will be readily apparent to those of skill in
the art.
Unless more specifically defined below, terminology as used herein is given
its ordinary meaning, "%" and like terms referring to weight percent unless
otherwise indicated. In general, when the composition of a support is being
discussed, the percentages in the composition include the oxygen as well as
the ions
or metals attached thereto, while when weights of catalytic metals are
discussed,
the weight of oxygen attached thereto is ignored. Thus, in a support
comprising 95%
silica and 5% alumina, this composition is based on alumina having a formula
weight
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of 101.94 and silica having a formula weight of 60.09. However, when we refer
to a
catalyst as having 2% platinum and 3% tin, the weight of any oxygen which may
be
attached thereto is ignored.
"Conversion" is expressed as a mole percentage based on acetic acid in the
feed.
mmol AcOH in (feed stream) - mmol AcOH out (GC)
AcOH conversion (%) = 100 * ---------------------------------------------------
----------------
mmol AcOH in (feed stream)
"Selectivity" is expressed as a mole percent based on converted acetic acid.
For example, if the conversion is 50 mole % and 50 mole % of the converted
acetic
acid is converted to ethanol, we refer to the ethanol selectivity as 50%.
Ethanol
selectivity is calculated from gas chromatography (GC) data as follows:
mmol EtOH out (GC)
Selectivity to EtOH (%) = 100 * -----------------------------------------------
-------------------
Total mmol C out (GC) - mmol AcOH out (GC)
2
Without intending to be bound by theory, it is believed the conversion of
acetic acid to ethanol in accordance with the invention involves one or more
of the
following reactions:
Hydrogenation of Acetic Acid to Ethanol.
Error! Objects cannot be created from editing field codes.
Hydrogenation of Acetic Acid to Ethyl Acetate
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Error! Objects cannot be created from editing field codes.
Cracking of Ethyl Acetate to Ethylene and Acetic Acid
Error! Objects cannot be created from editing field codes.
Dehydration of Ethanol to Ethylene
Error! Objects cannot be created from editing field codes.
Selective catalysts for catalytic hydrogenation of acetic acid to ethanol are
those chosen the group consisting of:
(i ) catalysts combining a platinum group metal chosen the group
consisting of platinum, palladium, and mixtures thereof with tin or
rhenium on silicaceous supports chosen from the group consisting of
silica, calcium metasilicate, or silica promoted with calcium
metasilicate;
(ii) catalysts combining palladium and rhenium supported on a
silicaceous support as described above optionally promoted with one
to 5% of a first promoter chosen group consisting of: alkali metals;
alkaline earth elements and zinc, promoter being preferably added to
the catalyst formulation in the form of the respective nitrates or
acetates, of the these promoters, particularly preferred are
potassium, cesium, calcium, magnesium and zinc;
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(iii) platinum promoted with cobalt on a silicaceous support; and
(iv) palladium promoted with cobalt on a silicaceous support.
The process of the invention may be practiced in a variety of configurations
using a fixed bed reactor or a fluidized bed reactor as one of skill in the
art will
readily appreciate. In many embodiments of the present invention, an
"adiabatic"
reactor can be used, i.e., there is little or no need for internal plumbing
through the
reaction zone to add or remove heat. Alternatively, a shell and tube reactor
provided with a heat transfer medium can be used. In many cases, the reaction
zone may be housed in a single vessel or in a series of vessels with heat
exchange
inbetween. It is considered significant that acetic acid reduction processes
using the
catalysts of the present invention may be carried out in adiabatic reactors as
this
reactor configuration is typically far less capital intensive than tube and
shell
configurations.
Various catalyst supports known in the art can be used to support acetic acid
hydrogenation catalysts. Examples of such supports include without any
limitation,
iron oxide, silica, alumina, titania, zirconia, magnesium oxide, calcium
silicate,
carbon, graphite and mixtures thereof. We prefer use of a silicaceous support
chosen from the group consisting of silica, calcium metasilicate and silica
promoted
with calcium silicate for the present invention, with pyrogenic silica having
an SiO2
content of at least 99.7% being especially desirable when pelletized into a
form
dense enough for use in fixed bed reactors. We have found that high purity,
high
surface area silica, especially grade HSA SS 61138 from Saint-Gobain NorPro,
optionally promoted with calcium metasilicate is unexpectedly superior to
other
supports for the catalysts of the present invention. It is preferred that
silica used as
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a support in the present invention have a surface area of at least 100 m2/g,
more
preferably at least 150 m2/g, more preferably at least 200 m2 /g and most
preferably
about 250 m2/g. Throughout this specification, the term "high surface area
silica"
should be understood to signify silica having a surface area of at least 250
m2/g. The
activity/stability of the silicaceous support may be modified by inclusion of
minor
amounts other constituents as described hereinbelow. Any convenient particle
shape including pellets, extrudates, spheres, spray dried, rings, pentarings,
trilobes
and quadrilobes may be used, although for this application we generally prefer
to
use cylindrical pellets.
Influence of the Catalyst Suppport.
Aside from the choice of metal precursor (i.e., halogen, Cl- vs. halogen-free,
N03) and preparation conditions, the resulting metal-support interactions
strongly
depend on structure and properties of the underlying support.
The effects of basic and acidic modifiers was studied for a variety of silica-
supported Pt-Sn materials. The molar ratio between Pt and Sn was maintained at
1:1 for all materials, and the total metal loading was also kept constant
unless stated
otherwise. Notably, the catalysts prepared on acidic supports, such as Si02,
Si02-
Ti02, KA160 (i.e., Si02-AI203), and H-ZSM5 give rise to high conversions in
acetic acid,
but lower selectivity towards ethanol. Interestingly, the H-ZSM5 catalyst
actually
produces diethylether as the main product, most likely formed by dehydration
from
ethanol. Both the catalysts based on Si02-TiO2 and KA160 (i.e., Si02-AI203)
give high
conversions and similar selectivities for EtOH and EtOAc with EtOAc being the
main
product in both cases. It appears, that the presence of Lewis acidity in the
underlying catalyst support may be beneficial for higher conversions of acetic
acid.
While the acidity in Si02-TiO2 is mainly based on Lewis acidity, the KA160
(silica-
alumina) material also has strongly acidic Bronsted sites which can catalyze
the
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formation of EtOAc from residual acetic acid and EtOH. The catalyst based on H-
ZSM5 has even more strongly acidic, zeolytic Bronsted sites, and the shape
selectivity due to the small pores may also be contributing to the acid-
catalyzed
formation of diethylether by ethanol dehydration. The addition of a basic
modifier
to any of the supports studied resulted generally in an increase of the
selectivity
towards ethanol, accompanied by a significant reduction of the acetic acid
conversion. The highest selectivity for ethanol with 92 % was found for Si02-
CaSi03(5)-Pt(3)-Sn(1.8), Table A, entry 2, and even pure TiO2, promoted with
CaSiO3
produced ethanol with a selectivity of about 20 %. A comparison between SiO2-
TiO2
and Ti02-CaSiO3 suggests that the site density of the acidic (Lewis) sites may
also be
of importance, and further optimization of the acidic properties of the
catalyst
supports can most likely be achieved by careful variation of basic and acidic
promoters combined with specific methods of preparation.
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Table A. Summary of catalyst activity data for catalyst support modifiers in
the gas-
phase hydrogenation of acetic acid. Reaction Conditions: 2.5 mt solid catalyst
(14/30 mesh,
diluted 1:1 (v/v, with quartz chips, 14/30 mesh); p = 200 psig (14 bar); 0.09
g/min HOAc; 160
sccm/min H2i 60 sccm/min N2; GHSV = 6570 h-1; 12 h of reaction time.
Entry Catalyst' Product Selectivity (%)2 HOAc3
No. Cony. (%)
AcH EtOH EtOAc
1 Si02-Pt,(Snl_,,; x = 0.50 - 74 26 73
2 Si02-CaSiO3(5)-Pt(3)-Sn(1.8) 2 92 6 24
3 Si02-WO3(10)-Pt(3)-Sn(1.8) - 77 23 17
4 Si02-TiO2(10)-Pt(3)-Sn(1.8) - 47 53 73
5 Ti02-CaSiO3(5)-Pt(3)-Sn(1.8) - 22 78 38
6 KA160-Pt(3)-Sn(1.8) 1 47 52 61
7 KA160-CaSiO3(8)-Pt(3)-Sn(1.8) 1 84 15 43
8 (H-ZSM-5)-Pt(3)-Sn(1.8)4 - - 4 784
9 Si02-RexPdl_x; x = 0.75 - 56 44 9
Si02-CaSiO3(5)-Re(4.5)-Pd(1) - 83 17 8
1 The preparation of the individual catalysts is described in detail herein.
The numbers in parentheses
represent the amount of the actual component (metal, metal oxide) in wt%.
2 Product selectivity (wt%) was calculated by from authentic sample calibrated
GC analyses.
10 3 The acetic acid conversion (%) was calculated by: [HOAc] Conversion, % =
{[HOAc] (Feed,
mmol/min) - [HOAc] (Effluent, mmol/min)/ [HOAc] (Feed, mmol/min)} * 100.
4 The main product obtained with this catalyst is diethyl ether, EtOEt, with a
selectivity of 96 %, and a
productivity of 2646 g/kg/h.
A significant shift in selectivity towards ethanol was observed comparing
KA160
(Si02-5% A1203) with the KA160-CaSiO3 - promoted catalyst. Although at 84 %,
the
selectivity with this catalyst is still lower than that observed for the Si02-
CaSiO3 -
based material, conversion of acetic acid remains at 43 %, almost double of
that
seen for Si02-CaSiO3(5)-Pt(3)-Sn(1.8), see Table A, entries 2, 6 and 7. In
addition to
the "acidic modifier" properties, all CaSiO3 - promoted materials appear to
show
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improved longer-term stability (albeit at lower conversions). Specifically,
the Si02-
CaSi03(5)-Pt(3)-Sn(1.8) catalyst exhibited less than 10 % activity decrease
over more
than 220 hrs of reaction time under various reaction conditions. The two Re-Pd
catalysts, prepared on SiO2 and Si02-CaSiO3 also show similar trends with
respect to
selectivity. Althoug the conversion remained below 10% for both materials, a
significant shift in selectivity towards ethanol was observed for the CaSiO3 -
promoted material, Table A, entries 9 and 10. Additional information on
productivities is provided in Table 4.
Accordingly, without being bound by theory, modification and stabilization of
oxidic supports for acetic acid hydrogenation catalysts by incorporation of
non-
volatile stabilizer-modifiers having either the effect of: counteracting acid
sites
present upon the surface thereof; or the effect of thermally stabilizing the
surface
makes it possible to achieve desirable improvements in selectivity to ethanol,
prolonged catalyst life; or both. In general, modifiers based on oxides in
their most
stable valence state will have low vapor pressure and thus are rather non-
volatile.
Accordingly, it is preferred that hydrogenation catalysts based on group VIII
metals
(Fe, Co, Ni, Ru, Rh, Pd, Ir, Pt and Os) or other transition metals (notably
Ti, Zn, Cr, Mo
and W) on oxidic supports incorporate basic non-volatile stabilizer-modifiers
on the
surface of or into the support itself in the form of oxides and metasilicates
of
alkaline earth metals, alkali metals, zinc, scandium, yttrium, precursors for
the
oxides and metasilicates, and mixtures thereof in amounts sufficient to
counteract
acidic sites present on the surface thereof, impart resistance to shape change
(primarily due to inter alia sintering, grain growth, grain boundary
migration,
migration of defects and dislocations, plastic deformation and/or other
temperature induced changes in microstructure) at temperatures encountered in
hydrogenation of acetic acid; or both.
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The amount of metal loading on support is not extremely critical in this
invention and can vary in the range of about 0.3 weight percent to about 10
weight
percent. A metal loading of about 0.5 weight percent to about 6 weight percent
based on the weight of the catalyst is particularly preferred. Due to extreme
costliness, platinum group metals are typically used in rather carefully
controlled
amounts, often less than 10% by weight of the entire catalytic composition. As
little
as 0.25-5 % platinum, when combined with the other catalytic elements as
described
herein, can provide excellent selectivity, life and activity. Typically, we
prefer using
between 0.5-5%, more preferably 1-3% platinum in the platinum containing
catalysts of the present invention. In the case of platinum tin catalysts, we
prefer to
use from 0.10 to 5% tin, more preferably 0.25 to 3% tin, still more preferably
0.5 to
2.5% tin and most preferably a combination of about 3% platinum and about 1.5%
tin corresponding rather closely to a 1:1 molar ratio of platinum to tin when
supported on high surface area silica/calcium metasilicate or lesser
proportionate
amounts based on lower weight percentage of platinum. For this catalyst, we
prefer
to use a silicaceous support chosen from the group consisting of high purity
high
surface area silica as described above, calcium metasilicate and high surface
area
silica promoted with calcium metasilicate. Accordingly, it can be appreciated
that
the amount of calcium metasilicate can vary widely ranging from 0 up to 100%
by
weight. As the calcium metasilicate tends to have lower surface area, we
prefer to
include at least about 10% high surface area silica in our supports for this
catalyst,
more preferably as our support, we prefer to use approximately 95% high
surface
area silica, SS61138 High Surface Area (HSA) Silica Catalyst Carrier from
Saint-Gobain NorPro having a surface area of 250 m2/g; a median pore diameter
of
12 nm; a total pore volume of 1.0 cm3/g as measured by mercury intrusion
porosimetry and a packing density of about 22 Ibs/ft3.
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Catalysts of the present invention are particulate catalysts in the sense
that,
rather than being impregnated in a wash coat onto a monolithic carrier similar
to
automotive catalysts and diesel soot trap devices, our catalysts are formed
into
particles, sometimes also referred to as beads or pellets, having any of a
variety of
shapes and the catalytic metals are provided to the reaction zone by placing a
large
number of these shaped catalysts in the reactor. Commonly encountered shapes
include extrudates of arbitrary cross-section taking the form of a generalized
cylinder in the sense that the generators defining the surface of the
extrudate are
parallel lines. Spheres, spray dried microspheres, rings, penta-rings and
multi-lobal
shapes are all usable. Typically, the shapes are chosen empirically based upon
perceived ability to contact the vapor phase with the catalytic agents
effectively.
A highly suitable platinum tin catalyst comprises about 3% platinum, 1.5 %
tin by weight supported on a high surface area silica having a surface area of
about
250 m2 /g promoted with from about 0.5% to 7.5% calcium metasilicate. We have
already achieved catalyst life in the hundreds of hours of time on stream at
280 C
with this composition. In many cases, it will be possible to partially
substitute
palladium for platinum in the above mentioned compositions.
Catalyst similar to those described in the preceding paragraph but containing
lesser amounts of the extremely costly platinum promoted with rather large
amounts of cobalt provide good initial catalytic activities but tend not to
exhibit as
prolonged catalyst lives as the platinum tin catalysts described above. The
hierarchy
of preference for silicaceous support for this catalyst is essentially the
same as that
for the platinum tin catalysts. Preferred catalysts of this class include from
0.25 to
5% platinum, more preferably 0.3 to 3% platinum, most preferably 0.5 to 1.5%
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platinum combined with from about 1% to about 20% cobalt, more preferably from
about 2% to about 15% cobalt and more preferably from about 8 to 12% cobalt.
Even though these catalysts are not so durable as the platinum tin catalysts
described above, in many cases, this will be largely offset by the greatly
decreased
amount of platinum required, the lower cost of cobalt as compared to the
platinum
group metals and the excellent initial selectivity. It is, of course, well
understood
that in many cases, it is possible to compensate for lack of activity by
appropriate
recycle streams or use of larger reactors, but it is more difficult to
compensate for
poor selectivity.
Catalysts based on palladium promoted with rhenium or cobalt provide
excellent catalytic activity with somewhat lower selectivity, this loss of
selectivity
being aggravated at reaction temperatures above 280 C resulting in the
formation of
increased amounts of acetaldehyde, carbon dioxide and even hydrocarbons. The
cobalt containing catalysts typically exhibit slightly better selectivity than
the
corresponding rhenium catalyst; but, while both provide surprisingly long-
lived
catalytic activity, neither provides catalyst life which is as outstanding as
of that of
the most preferred platinum/tin catalysts on high purity alumina stabilized
with and
modified by calcium metasilicate. Again this catalyst may be supported on the
silicaceous supports stabilized with and modified by the oxides and
metasilicates of
Group I, Group II and zinc described above as well as the precursors therefor
and
mixtures thereof. Highly suitable precursors include the acetates and nitrates
of
zinc, the alkali metals and the alkaline earth metals which may optionally be
incorporated into the silicaceous support in the amount of about 1 to 5% based
on
the weight of the metal excluding the acetate and/or nitrate moieties.
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In other embodiments of the present invention, the catalysts described
above may be modified by incorporating modifiers chosen from the group
consisting
of redox-active modifiers; acidic modifiers and mixtures thereof into the
silicaceous
support thereby changing the relative selectivity between ethanol, ethyl
acetate and
acetaldehyde. Suitable redox-active modifiers include W03; MoO3; Fe2O3 and
Cr2O3
while acidic modifiers include Ti02; ZrO2; Nb2O5; Ta205; and A12O3. By
judicious
incorporation of these modifiers into the silicaceous support, the activity of
the
catalyst may be tuned to produce more desirable distributions of relative
amounts
of the products the catalytic hydrogenation to accord with fluctuations in
markets
and the demands for the various products. Typically, these materials will be
included
in the silicaceous support in amounts ranging from about 1 to 50% by weight
thereof.
The metal impregnation can be carried out using any of the known methods
in the art. Typically, before impregnation, the supports are dried at 120 C
and
shaped to particles having size distribution in the range of about 0.2 to 0.4
mm.
Optionally, the supports may be pressed, crushed and sieved to a desired size
distribution. Any of the known methods to shape the support materials into
desired
size distribution can be employed. In a preferred method of preparing the
catalyst,
a platinum group metal component such as a suitable compound and/or complex of
the platinum group metals can be utilized to achieve dispersion of the
catalytic
component on the support, e.g., support particles. Water soluble compounds or
water dispersible compounds or complexes of platinum group metals can be
utilized
to impregnate or deposit the catalytic metal compounds onto support particles.
The
platinum group metal component decomposes upon heating and/or the application
of vacuum. In some cases, the completion of removal of the liquid may not take
place until the catalyst is placed into use and subjected to the high
temperatures
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encountered during operation. Generally, both from the point of view of
economics
and environmental aspects, aqueous solutions of soluble compounds of the
platinum group metals are preferred. For example, suitable compounds are
chloroplatinic acid, amine solubilized platinum hydroxide, palladium nitrate
or
palladium chloride, sodium palladium chloride, sodium platinum chloride and
the
like, although we prefer to avoid use of halogens when ethanol is the desired
product. During the calcination step, or at least during the initial phase of
use of the
catalyst, such compounds are converted into a catalytically active form of the
platinum group metal or a catalytically active oxide thereof. In general
however, we
prefer to use platinum group metal precursors which are chloride free as we
have
found that catalysts prepared from Pt(NH3)4(NO4)z seem to exhibit increased
selectivity to ethanol.
Inasmuch as the catalysts of the present invention are bimetallic, is
generally
considered that, in such cases, one metal acts as a promoter metal and the
other
metal is the main metal. For instance, in the case of the platinum tin
catalyst,
platinum might be considered to be the main metal for preparing hydrogenation
catalysts of this invention, while tin would be considered a promoter metal.
However, it should be noted that sometimes such distinctions can be deceptive
particularly in this case wherein the selectivity of platinum tin catalyst for
ethanol,
the desired product, approaches zero both in the absence of tin and in the
absence
of platinum. For convenience, we prefer to refer to the platinum group metal
or
metals as the primary catalyst and the other metals as the promoters. This
should
not be taken as an indication of the underlying mechanism of the catalytic
activity.
Bimetallic catalysts are often impregnated in two steps. First, the
"promoter" metal is added, followed by "main" metal. Each impregnation step is
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followed by drying and calcination. Bimetallic catalysts may also be prepared
by
co-impregnation. In the case of promoted bimetallic catalysts as described
above, a
sequential impregnation may be used, starting with the addition of the
"promoter
metal followed by a second impregnation step involving co-impregnation of the
two
principal metals, i.e., Pt and Sn. For example, PtSn/CaSi03on SiO2 may be
prepared
by a first impregnation of CaSiO3 onto the Si02, followed by the co-
impregnation
with dilute admixtures of chloroplatinic acid, amine solubilized platinum
hydroxide,
palladium nitrate or palladium chloride, sodium palladium chloride, sodium
platinum
chloride, Pt(NH3)4(NO4)2 and the like. Again, each impregnation is followed by
drying
and calcinations. In most cases, the impregnation may be carried out using
metal
nitrate solutions. However, various other soluble salts which upon calcination
releases metal ions can also be used. Examples of other suitable metal salts
for
impregnation include, metal acids, such as perrhenic acid solution, metal
oxalate,
and the like. In those cases where substantially pure ethanol is to be
produced, it is
generally preferable to avoid the use of halogenated precursors for the
platinum
group metals, using the nitrogenous amine and/or nitrate based precursors
instead.
The reaction may be carried out in the vapor state under a wide variety of
conditions. Preferably, the reaction is carried out in the vapor phase.
Reaction
temperatures may be employed, for example in the range of about 125 C to 350
C,
more commonly from about 200 C to about 325 C, preferably from about 225 C to
about 300 C and most preferably from about 250 C to about 300 C. The pressure
is
generally uncritical to the reaction and subatmospheric, atmospheric or
superatmospheric pressures may be employed. In most cases, however, the
pressure of the reaction will be in the range of about 1 to 30 atmospheres
absolute.
In another aspect of the process of this invention, the hydrogenation
typically can be
carried out at a pressure just sufficient to overcome the pressure drop across
the
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catalytic bed at the gross hourly space velocity ("GHSV") selected , although
there is
no bar to the use of higher pressures, it being understood that considerable
pressure drop through the reactor bed may be experienced at the space
velocities of
5000 hr -1 and 6,500 hr -1 easily usable with the catalysts of the present
invention.
Although the reaction consumes two moles of hydrogen per mole of acetic
acid to produce a mole of ethanol, the actual molar ratio of hydrogen to
acetic acid
in the feed stream may be varied between wide limits, e.g. from about 100:1 to
1:100. It is preferred however that such ratio be in the range of about 1:20
to 1:2.
Most preferably, the molar ratio of hydrogen to acetic acid is about 5: 1.
The raw materials used in connection with the process of this invention may
be derived from any suitable source including natural gas, petroleum, coal,
biomass
and so forth. It is well known to produce acetic acid through methanol
carbonylation, acetaldehyde oxidation, ethylene oxidation, oxidative
fermentation,
and anaerobic fermentation and so forth. As petroleum and natural gas
fluctuate
becoming either more or less expensive, methods for producing acetic acid and
intermediates such as methanol and carbon monoxide from alternate carbon
sources have drawn increasing interest. Particularly, when petroleum is
relatively
expensive compared to natural gas, it may become advantageous to produce
acetic
acid from synthesis gas ("syn gas") that derived from any suitable carbon
source.
United States Patent No. 6,232,352 to Vidalin, the disclosure of which is
incorporated herein by reference, for example, teaches a method of
retrofitting a
methanol plant for the manufacture of acetic acid. By retrofitting a methanol
plant
the large capital costs associated with CO generation for a new acetic acid
plant are
significantly reduced or largely eliminated. All or part of the syn gas is
diverted from
the methanol synthesis loop and supplied to a separator unit to recover CO and
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hydrogen, which are then used to produce acetic acid. In addition to acetic
acid, the
process can also be used to make hydrogen which is utilized in connection with
this
invention.
United States Patent No. RE 35,377 Steinberg et al., also incorporated herein
by reference, provides a method for the production of methanol by conversion
of
carbonaceous materials such as oil, coal, natural gas and biomass materials.
The
process includes hydrogasification of solid and/or liquid carbonaceous
materials to
obtain a process gas which is steam pyrolized with additional natural gas to
form
synthesis gas. The syn gas is converted to methanol which may be carbonylated
to
acetic acid. The method likewise produces hydrogen which may be used in
connection with this invention as noted above. See also, United States Patent
No.
5,821,111 Grady et al., which discloses a process for converting waste biomass
through gasification into synthesis gas as well as United States Patent No.
6,685,754
Kindig et al., the disclosures of which are incorporated herein by reference.
The acetic acid may be vaporized at the reaction temperature, and then it
can be fed along with hydrogen in undiluted state or diluted with a relatively
inert
carrier gas, such as nitrogen, argon, helium, carbon dioxide and the like.
Alternatively, acetic acid in vapor form may be taken directly as crude
product from the flash vessel of a methanol carbonylation unit of the class
described
in United States Patent No. 6,657,078 of Scates et al., the disclosure of
which is
incorporated herein by reference. The crude vapor product may be fed directly
to
the reaction zones of the present invention without the need for condensing
the
acetic acid and light ends or removing water, saving overall processing costs.
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Contact or residence time can also vary widely, depending upon such
variables as amount of acetic acid, catalyst, reactor, temperature and
pressure.
Typical contact times range from a fraction of a second to more than several
hours
when a catalyst system other than a fixed bed is used, with preferred contact
times,
at least for vapor phase reactions, between about 0.5 and 100 seconds.
Typically, the catalyst is employed in a fixed bed reactor e.g. in the shape
of
an elongated pipe or tube where the reactants, typically in the vapor form,
are
passed over or through the catalyst. Other reactors, such as fluid or
ebullient bed
reactors, can be employed, if desired. In some instances, the hydrogenation
catalysts may be used in conjunction with an inert material such as glass wool
to
regulate the pressure drop of the reactant stream through the catalyst bed and
the
contact time of the reactant compounds with the catalyst particles.
The following examples describe the procedures used for the preparation of
various catalysts employed in the process of this invention. Throughout these
Preparations and Examples, where a lower case or minuscule script 'T' is used,
it is
used to avoid ambiguity between the lower case letter "I", the numeral "1" and
the
upper case or majuscule letter "I" inherent in many fonts and/or typefaces
and,
since the meaning of language flows from common usage, should be understood to
indicate "liters" or "litres" despite the lack of any international sanction
therefor.
Catalyst Preparations (general).
The catalyst supports were dried at 120 C overnight under circulating air
prior to use. All commercial supports (i.e., Si02, Zr02) were used as a 14/30
mesh, or
in its original shape (1/16 inch or 1/8 inch pellets) unless mentioned
otherwise.
Powdered materials (i.e., CaSiO3) were pelletized, crushed and sieved after
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metals had been added. The individual catalyst preparations are described in
detail
in the following Section.
Catalyst Preparation A
Preparation of 0.5 wt% platinum and 5 wt% tin on High Purity Low Surface Area
Silica
Powdered and meshed high surface area silica NPSG SS61138 (100 g) of
uniform particle size distribution of about 0.2 mm was dried at 1202C in an
oven
under nitrogen atmosphere overnight and then cooled to room temperature. To
this was added a solution of platinum nitrate (Chempur) (0.82 g) in distilled
water
(8 mt) and a solution of tin oxalate (Alfa Aesar) (8.7 g) in dilute nitric
acid (1N,
43.5 ml). The resulting slurry was dried in an oven gradually heated to 1102C
(>2 hours, 102C/min.). The impregnated catalyst mixture was then calcined at
5002C
(6 hours, 12C/min).
Catalyst Preparation B
Preparation of 1 wt.% platinum and 1 wt.% tin on High Surface Area Silica
The procedures of Catalyst Prep A was substantially repeated except for
utilizing a solution of platinum nitrate (Chempur) (1.64 g) in distilled water
(16 mf)
and a solution of tin oxalate (Alfa Aesar) (1.74 g) in dilute nitric acid (1N,
8.5 mC).
Catalyst Preparation C
Preparation of 1 wt. % platinum and 1 wt.% tin on Calcium meta-Silicate
The procedures of Catalyst Prep B was substantially repeated except for
utilizing a solution of platinum nitrate (Chempur) (1.64 g) in distilled water
(16 mt)
and a solution of tin oxalate (Alfa Aesar) (1.74 g) in dilute nitric acid (1N,
8.5 mC),
and utilizing calcium meta-silicate as a catalyst support.
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Catalyst Preparation D
Preparation of 0.5 wt.% platinum, 0.5 wt.% tin and 0.2 wt.% cobalt on High
Surface
Area Silica
Powdered and meshed high surface area silica (100 g) of uniform particle size
distribution of about 0.2 mm was dried at 1200C in an oven under nitrogen
atmosphere overnight and then cooled to room temperature. To this was added a
solution of platinum nitrate (Chempur) (0.82 g) in distilled water (8 mC) and
a
solution of tin oxalate (Alfa Aesar) (0.87 g) in dilute nitric acid (1N, 4.5 m-
C). The
resulting slurry was dried in an oven gradually heated to 1102C (>2 hours,
109C/min.). The impregnated catalyst mixture was then calcined at 5002C (6
hours,
1 C/min). To this calcined and cooled material was added a solution of cobalt
nitrate hexahydrate (0.99 g) in distilled water (2 ml). The resulting slurry
was dried
in an oven gradually heated to 1102C (>2 hours, 102C/min.). The impregnated
catalyst mixture was then calcined at 5009C (6 hours, 1QC/min).
Catalyst Preparation E
Preparation of 0.5 wt.% tin on High Purity Low Surface Area Silica.
Powdered and meshed high purity low surface area silica (100 g) of uniform
particle size distribution of about 0.2 mm was dried at 1202C in an oven under
nitrogen atmosphere overnight and then cooled to room temperature. To this was
added a solution of tin oxalate (Alfa Aesar) (1.74 g) in dilute nitric acid
(1N, 8.5 mC).
The resulting slurry was dried in an oven gradually heated to 1100C (>2 hours,
102C/min.). The impregnated catalyst mixture was then calcined at 5002C (6
hours,
12C/min).
Catalyst Preparation F
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Preparation of 2 wt.% platinum and 2 wt.% tin on High Surface Area Silica
Powdered and meshed high surface area silica NPSG SS61138 (100 g) of
uniform particle size distribution of about 0.2 mm was dried at 1202C in a
circulating
air oven atmosphere overnight and then cooled to room temperature. To this was
added a solution of nitrate hexahydrate Chempur). The resulting slurry was
dried in
an oven gradually heated to 1102C (>2 hours, 102C/min.) then calcined. To this
was
added a solution of platinum nitrate (Chempur) in distilled water and a
solution of
tin oxalate (Alfa Aesar) in dilute nitric acid. The resulting slurry was dried
in an oven
gradually heated to 1102C (>2 hours, 109C/min.). The impregnated catalyst
mixture
was then calcined at 5002C (6 hours, 12C/min).
Catalyst Preparation G
Preparation of 1 wt% platinum and 1 wt% tin on High Surface Area Silica
Promoted
with 5% ZnO
The procedure of Catalyst Prep F was substantially repeated except that:
a solution of zinc nitrate hexahydrate was added to high surface area silica
as
described in Catalyst Preparation F. The resulting slurry was dried in an oven
gradually heated to 1102C (>2 hours, 102C/min.) then calcined. Thereafter,
a solution of platinum nitrate (Chempur) in distilled water and a solution of
tin
oxalate (Alfa Aesar) (1.74 g) in dilute nitric acid (1N, 8.5 mg) was
thereafter added to
the zinc promoted high surface area silica.
Catalyst Preparation H.
Preparation of 1 wt% platinum and 1 wt% Zn on High Surface Area Silica
Promoted
with 5% SnO2
The procedure of Catalyst Prep G was substantially repeated except that:
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a solution of tin acetate (Sn(OAc)2) was added to a high surface area silica
instead of
the zinc nitrate hexahydrate; and a solution of platinum nitrate,
Pt(NH3)4(NO3)2
(Aldrich) in distilled water and a solution of tin oxalate (Alfa Aesar) in
dilute nitric
acid.
Catalyst Preparation I
Preparation of 1.5 wt% platinum, 0.5 wt% tin on calcium metasilicate
The procedure of Catalyst Prep C above was repeated utilizing a solution of
platinum nitrate (Chempur) in distilled water and a solution of tin oxalate
(Alfa
Aesar) in dilute nitric acid.
Catalyst Preparation J
Preparation of 1.5 wt% platinum, 10 wt% cobalt on high surface area silica
The procedure of Catalyst Prep H. above was repeated utilizing a solution of
platinum nitrate (Chempur) in distilled water and, instead of the stannous
octoate, a
solution of cobalt(II) nitrate hexahydrate (1.74 g). The compositions of the
catalysts
prepared as well as summaries of the compositions of other catalyst prepared
by
analogous procedures and tested herein are indicated in Table 1.
Catalyst Preparations K - 0
SiO2-Pt,Snl_,(0 <x < 1). Five materials were prepared varying the mol
fraction of Pt while maintaining a total metal amount (Pt + Sn) of 1.20 mmol.
The
following preparation describes the procedure for Catalyst Preparation K, Si02-
Pto.5Sn0_5 (i.e., x = 0.5; equimolar ratio of both metals). The remaining
preparations
(i.e., x = 0, 0.25, 0.75, and 1.00; Catalyst Prep's L, M, N and 0
respectively) were
carried out identically using the appropriate amounts of the metal precursors
Pt(NH3)4(NO3)2 and Sn(OAc)2. The catalysts were prepared by first adding
Sn(OAc)2
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(tin acetate, Sn(OAc)2 from Aldrich ) (0.1421 g, 0.60 mmol) to a vial
containing 6.75
mC of 1:1 diluted glacial acetic acid (Fisher). The mixture was stirred for 15
min at
room temperature, and then, 0.2323 g (0.60 mmol) of solid Pt(NH3)4(NO3)2
(Aldrich)
were added. The mixture was stirred for another 15 min at room temperature,
and
then added drop wise to 5.0 g of dry Si02 catalyst support (high purity silica
catalyst
support HSA SS #61138, SA = 250 m2/g; SZ #61152, SA = 156 m2/g; Saint-Gobain
NorPro), in a 100 m1 round-bottomed flask. The metal solution was stirred
continuously until all of the Pt/Sn mixture had been added to the Si02
catalyst
support while rotating the flask after every addition of metal solution. After
completing the addition of the metal solution, the flask containing the
impregnated
catalyst was left standing at room temperature for two hours. The flask was
then
attached to a rotor evaporator (bath temperature 80 C), and evacuated til
dried
while slowly rotating the flask. The material was then dried further overnight
at
120 C, and then calcined using the following temperature program: 25 -f
160 C/ramp 5.0 deg/min; hold for 2.0 hours; 160 -> 500 C/ramp 2.0 deg/min;
hold
for 4 hours. Yield: 5.2 g of dark grey material.
Catalyst Preparation P
SiO2-CaSiO3(5)-Pt(3)-Sn(1.8). The material was prepared by first adding
CaSiO3 (Aldrich) to the Si02 catalyst support, followed by the addition of
Pt/Sn as
described previously. First, an aqueous suspension of CaSiO3 (<_ 200 mesh) was
prepared by adding 0.52 g of the solid to 13 mE of deionized H20, followed by
the
addition of 1.0 mC of colloidal Si02 (15 wt% solution, NALCO). The suspension
was
stirred for 2 h at room temperature and then added to 10.0 g of Si02 catalyst
support (14/30 mesh) using incipient wetness technique. After standing for 2
hours,
the material was evaporated to dryness, followed by drying at 120 C overnight
under circulating air and calcination at 500 C for 6 hours. All of the Si02-
CaSiO3
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material was then used for Pt/Sn metal impregnation using 0.6711 g (1.73 mmol)
of
Pt(NH3)4(NO3)2 and 0.4104 g (1.73 mmol) of Sn(OAc)2 following the procedure
described above for the SiO2-Pt),Sn1_X materials. Yield: 11.21 g of dark grey
material.
Catalyst Preparation Q
CaSIO3-Pt(1)-Sn(1). To a 100 mt round-bottomed flask containing a Teflon-
coated magnetic stir bar, 40 mf of 1.0 M NHO3 was added, followed by the
addition
of 0.2025 g (0.52 mmol) of solid Pt(NH3)4(NO3)2. The Pt complex was dissolved
with
stirring and 0.2052 g (0.87 mmol) of solid Sn(OAc)2 was then added. Next, 10.0
g of
CaSiO3 (_< 200 mesh) was added with stirring; the mixture was then heated to
80 C
and stirred for two hours at this temperature. The suspension was then
evacuated
to dryness using a rotor evaporator (bath temperature 80 C), the solid
transferred
into a porcelain dish, and dried at 120 C overnight under circulation air.
After
calcination (25 C -* 160 C/ramp @5.0 deg/min; hold for 2.0 hours; 160 -*
500 C/ramp @2.0 deg/min; hold for 4 hours) the material was pressed,
pelletized
under pressure, our particular press applying a force of 40,000 lbs for 15
minutes,
and crushed and sieved to a 14/30 mesh. Yield: 9.98 g of a tan colored
material.
Catalyst Preparation R
SiO2-TiO2(10)-Pt(3)-Sn(1.8). The Ti02-modified silica support was prepared as
follows. A solution of 4.15 g (14.6 mmol) of Ti{OCH(CH3)2}4 in 2-propanol (14
m t)
was added dropwise to 10.0 g of Si02 catalyst support (1/16 inch extrudates)
in a
100 mt round-bottomed flask. The flask was left standing for two hours at room
temperature, and then evacuated to dryness using a rotor evaporator (bath
temperature 80 C). Next, 20 m1 of deionized H2O was slowly added to the flask,
and
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the material was left standing for 15 min. The resulting water/2-propanol was
then
removed by filtration, and the addition of H2O was repeated two more times.
The
final material was dried at 120 C overnight under circulation air, followed by
calcination at 500 C for 6 hours. All of the Si02-TiO2 material was then used
for
Pt/Sn metal impregnation using 0.6711 g (1.73 mmol) of Pt(NH3)4(NO3)2 and
0.4104 g
(1.73 mmol) of Sn(OAc)2 following the procedure described above for the Si02-
Pt),Sn1_X materials. Yield: 11.98 g of dark grey 1/16 inch extrudates.
Catalyst Preparation S
SiO2-WO3(10)-Pt(3)-Sn(1.8). The W03-modified silica support was prepared
as follows. A solution of 1.24 g (0.42 mmol) of (NH4)6H2W12040 = n H20, (AMT)
in
deionized H2O (14 mC) was added dropwise to 10.0 g of Si02 NPSGSS
61138catalyst
support (SA = 250 m2/g, 1/16 inch extrudates) in a 100 mà round-bottomed
flask.
The flask was left standing for two hours at room temperature, and then
evacuated
to dryness using a rotor evaporator (bath temperature 80 C). The resulting
material
was dried at 120 C overnight under circulation air, followed by calcination at
500 C
for 6 hours. All of the (light yellow) Si02-WO3 material was then used for
Pt/Sn
metal impregnation using 0.6711 g (1.73 mmol) of Pt(NH3)4(N03)2 and 0.4104 g
(1.73
mmol) of Sn(OAc)2 following the procedure described above for the Si02-
PtxSn1_X
materials. Yield: 12.10 g of dark grey 1/16 inch extrudates.
Catalyst Preparation T
(H-ZSM-5)-Pt(3)-Sn(1.8). The material was prepared by slurry impregnation
of H-ZSM-5 (prepared from NH4-ZSM-5 by calcination at 550 C for 8 hours under
air).
An aqueous solution of 0.6711 g (1.73 mmol) of Pt(NH3)4(NO3)2and 0.4104 g
(1.73
mmol) of Sn(OAc)2 was prepared by adding the components to 40 m f of 1:1
diluted
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acetic acid in a 100 mC round-bottomed flask and stirring the mixture for 15
min at
room temperature. Next, 10.0 g of solid, finely powdered H-ZSM-5 was added to
the
solution with stirring, and the mixture was stirred for another two hours at
room
temperature. The flask was then evacuated to dryness using a rotor evaporator
(bath temperature 80 C), and the resulting material was dried at 120 C
overnight
under circulation air. After calcination (250 C -+ 160 C/ramp 5.0 deg/min;
hold for
2.0 hours; 160 -* 500 C/ramp 2.0 deg/min; hold for 4 hours) the material was
pressed, pelletized, crushed and sieved to a 14/30 mesh. Yield: 9.55 g of a
grey
colored material.
Catalyst Preparation U
SiO2-Re,Pdl_,(0 <x < 1). Five materials were prepared varying the mol
fraction of Re while maintaining a total metal amount (Re + Pd) of 1.20 mmol.
The
following preparation describes the procedure for SiO2-Reo.5PdO.5 (i.e., x =
0.5;
equimolar ratio of both metals). The remaining preparations (i.e., x = 0,
0.25, 0.75,
and 1.00) were carried out identically using the appropriate amounts of the
metal
precursors NH4ReO4 and Pd(N03)2. The metal solutions were prepared by first
adding NH4ReO4 (0.1609 g, 0.60 mmol) to a vial containing 6.75 mE of deionized
H20-
The mixture was stirred for 15 min at room temperature, and 0.1154 g (0.60
mmol)
of solid Pd(N03)2was then added. The mixture was stirred for another 15 min at
room temperature, and then added drop wise to 5.0 g of dry Si02 catalyst
support
(14/30 mesh) in a 100 m.Ã round-bottomed flask. After completing the addition
of
the metal solution, the flask containing the impregnated catalyst was left
standing at
room temperature for two hours. The flask was then attached to a rotor
evaporator
(bath temperature 80 C), and evacuated to dryness. All other manipulations
(drying,
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calcination) were carried out as described above for the SiO2-Pt),Sn1_X
materials, vide
supra. Yield: 5.1 g of a brown material.
Catalyst Preparation V
SiO2-CaSiO3(5)-Re(4.5)-Pd(1). The Si02-CaSiO3(5) modified catalyst support
was prepared as described for Si02-CaSiO3(5)-Pt(3)-Sn(1.8), vide supra. The
Re/Pd
catalyst was prepared then by impregnating the Si02-CaSiO3(5) (1/16 inch
extrudates) with an aqueous solution containing NH4ReO4 and Pd(N03)2. The
metal
solutions were prepared by first adding NH4ReO4 (0.7237 g, 2.70 mmol) to a
vial
containing 12.0 mf of deionized H20. The mixture was stirred for 15 min at
room
temperature, and 0.1756 g (0.76 mmol) of solid Pd(N03)2was then added. The
mixture was stirred for another 15 min at room temperature, and then added
drop
wise to 10.0 g of dry Si02-(0.05)CaSiO3 catalyst support in a 100 mt round-
bottomed
flask. After completing the addition of the metal solution, the flask
containing the
impregnated catalyst was left standing at room temperature for two hours. All
other manipulations (drying, calcination) were carried out as described above
for the
Si02-RexPd1_x materials, vide supra. Yield: 10.9 g of brown material.
Catalyst Preparation W
CaSiO3-Re(5)-Pd(2.5). The material was prepared by slurry impregnation of
CaSiO3 (powder, <_ 200 mesh). An aqueous solution of 0.6169 g (2.30 mmol) of
NH4ReO4 and 0.5847 g (2.53 mmol) of Pd(N03)2 was prepared by adding the
components to 40 m f of deionized H2O in a 100 mt round-bottomed flask and
stirring the mixture for 15 min at room temperature. Next, 10.0 g of solid,
finely
powdered CaSiO3 was added to the solution with stirring, and the mixture was
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stirred for another two hours at room temperature. The flask was then
evacuated
to dryness using a rotor evaporator (bath temperature 80 C), and the resulting
material was dried at 120 C overnight under circulation air. All other
manipulations
(drying, calcination) were carried out as described above for the SiO2-
Re,Pd1_x
materials, vide supra. The final material was pressed, pelletized using a
press that
applies a force of 40,000 lbs for 15 minutes, crushed and sieved to a 14/30
mesh.
Yield: 10.65 g of a brown colored material.
Catalyst Preparation X
SiO2-Co(10)-Pt(1). The material was prepared by impregnating HSA SiO2
(14/30 mesh) with an aqueous solution containing Co(NO3)2 - 6 H2O and
Pt(NH3)4(NO3)2. The metal solutions were prepared by first adding Co(N03)2. 6
H2O
(5.56 g, 19.1 mmol) to a vial containing 12.0 mC of deionized H2O. The mixture
was
stirred for 15 min at room temperature, and 0.2255 g (0.58 mmol) of solid
Pt(NH3)4(NO3)2 was then added. The mixture was stirred for another 15 min at
room
temperature, and then added drop wise to 10.0 g of dry SiO2 catalyst support
(14/30
mesh) in a 100 mC round-bottomed flask. After completing the addition of the
metal solution, the flask containing the impregnated catalyst was left
standing at
room temperature for two hours. All other manipulations (drying, calcination)
were
carried out as described above for the SiO2-PtxSn1_X materials, vide supra.
Yield:
11.35 g of a black material.
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Catalyst Preparation Y
CaSiO3-Co(10)-Pt(1). The material was prepared by slurry impregnation of
CaSiO3 (powder, <_ 200 mesh). An aqueous solution of 5.56 g (19.1 mmol) of
Co(N03)2. 6 H2O and 0.2255 g (0.58 mmol) of Pt(NH3)4(NO3)2 was prepared by
adding the components to 40 mf of deionized H2O in a 100 mf round-bottomed
flask and stirring the mixture for 15 min at room temperature. Next, 10.0 g of
solid,
finely powdered CaSiO3 was added to the solution with stirring. The mixture
was
then heated to 65 C, and stirred for another two hours at this temperature.
The
flask was then evacuated to dryness using a rotor evaporator (bath temperature
80 C), and the resulting material was dried at 120 C overnight under
circulation air.
All other manipulations (drying, calcination) were carried out as described
above for
the Si02-Co(10)-Pt(1) material, vide supra. The final material was pressed,
pelletized
under pressure, crushed and sieved to a 14/30 mesh. Yield: 10.65 g of a black
material.
Catalyst Preparation Z
Zr02-Co(10)-Pt(1). The material was prepared by impregnating Zr02 (SZ
61152, Saint-Gobain NorPro, 14/30 mesh) with an aqueous solution containing
Co(N03)2. 6 H2O and Pt(NH3)4(NO3)2. The metal solutions were prepared by first
adding Co(N03)2. 6 H2O (5.56 g, 19.1 mmol) to a vial containing 5.0 mC of
deionized
H20. The mixture was stirred for 15 min at room temperature, and 0.2255 g
(0.58
mmol) of solid Pt(NH3)4(NO3)2 was then added. The mixture was stirred for
another
15 min at room temperature, and then added drop wise to 10.0 g of the dry Zr02
catalyst support (14/30 mesh) in a 100 ml round-bottomed flask. After
completing
the addition of the metal solution, the flask containing the impregnated
catalyst was
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left standing at room temperature for two hours. All other manipulations
(drying,
calcination) were carried out as described above for the Si02-Co(10)-Pt(1)
material,
vide supra. Yield: 11.35 g of a black material.
Catalyst Preparation AA
SiO2-CaSiO3(2.5)-Pt(1.5)-Sn(0.9).
The material was prepared as described above for Si02-CaSiO3(5)-Pt(3)-
Sn(1.8) using 0.26 g of CaSiO3, 0.5 mE of colloidal Si02 (15 wt% solution,
NALCO),
0.3355 g (0.86 mmol) of Pt(NH3)4(NO3)2 and 0.2052 g (0.86 mmol) of Sn(OAc)2.
Yield:
10.90 g of dark grey material.
Catalyst Preparation BB
TiO2-CaSiO3(5)-Pt(3)-Sn(1.8).
The material was prepared by first adding CaSiO3 to the Ti02 catalyst
(Anatase, 14/30 mesh) support, followed by the addition of Pt/Sn as described
previously. First, an aqueous suspension of CaSiO3 (5 200 mesh) was prepared
by
adding 0.52 g of the solid to 7.0 mà of deionized H20, followed by the
addition of 1.0
mC of colloidal Si02 (15 wt% solution, NALCO). The suspension was stirred for
2 h at
room temperature and then added to 10.0 g of Ti02 catalyst support (14/30
mesh)
using incipient wetness technique. After standing for 2 hours, the material
was
evaporated to dryness, followed by drying at 120 C overnight under circulating
air
and calcination at 500 C for 6 hours. All of the Ti02-CaSiO3 material was then
used
for Pt/Sn metal impregnation using 0.6711 g (1.73 mmol) of Pt(NH3)4(NO3)2 and
0.4104 g (1.73 mmol) of Sn(OAc)2 following the procedure described above for
the
Si02-Pt),Snl_,, materials. Yield: 11.5 g of light grey material.
Catalyst Preparation CC
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KA160-Pt(3)-Sn(1.8).
The material was prepared by incipient wetness impregnation of KA160
catalyst support (Si02-(0.05) AI203, Sud Chemie, 14/30 mesh) as described
previously for SiO2-Pt,,Sn1_X, vide infra. The metal solutions were prepared
by first
adding Sn(Oac)2 (0.2040 g, 0.86 mmol) to a vial containing 4.75 mC of 1:1
diluted
glacial acetic acid. The mixture was stirred for 15 min at room temperature,
and
then, 0.3350 g (0.86 mmol) of solid Pt(NH3)4(N03)2were added. The mixture was
stirred for another 15 min at room temperature, and then added drop wise to
5.0 g
of dry KA160 catalyst support (14/30 mesh) in a 100 mt round-bottomed flask.
All
other manipulations, drying and calcination was carried out as described above
for
SiO2-PtxSn1_X. Yield: 5.23 g of tan-colored material.
Catalyst Preparation DD
KA160-CaSiO3(8)-Pt(3)-Sn(1.8).
The material was prepared by first adding CaSiO3 to the KA160 catalyst
support, followed by the addition of Pt/Sn as described above for KA160-Pt(3)-
Sn(1.8). First, an aqueous suspension of CaSiO3 (<_ 200 mesh) was prepared by
adding 0.42 g of the solid to 3.85 m t of deionized H20, followed by the
addition of
0.8 m.C of colloidal Si02 (15 wt% solution, NALCO). The suspension was stirred
for
2 h at room temperature and then added to 5.0 g of KA160 catalyst support
(14/30
mesh) using incipient wetness technique. After standing for 2 hours, the
material
was evaporated to dryness, followed by drying at 120 C overnight under
circulating
air and calcinations at 500 C for 6 hours. All of the KA160-CaSiO3 material
was then
used for Pt/Sn metal impregnation using 0.3350 g (0.86 mmol) of Pt(NH3)4(NO3)2
and
0.2040 g (0.86 mmol) of Sn(Oac)2 following the procedure described above for
the
SiO2-PtxSn1_X materials. Yield: 5.19 g of tan-colored material.
Table 1
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Catalyst Summary
CP PGM Promoter other Support Ex
A 0.5 wt% Pt 5 wt% Sn -- HP LSA SiO2 1
B. 1 wt% Pt 1 wt% Sn -- HP LSA Si02 2
C 1 wt% Pt 1 wt% Sn -- CaSiO2 4
D. 0.5 wt% Pt 0.5 wt% Sn 0.2 wt% Co HP LSA Si02 --
E -- 0.5 wt% Sn -- HP LSA SiO2 CE1
F. 2 wt% Pt 2 wt% Sn -- HSA Si02
G 1 wt% Pt lwt% Sn 5 wt% ZnO HSA Si02 4
H 1 wt% Pt 1 wt% Zn 5SnO2 HSA Si02 4
I 1.5 wt% Pt 0.5 wt% Sn -- Ca Si02 4
J. 1 wt% Pt -- 10 wt% Co HSA SiO2 4
K Si02-PtxSn(l-x) (E [Pt] + [Sn] = 1.20 mmol HSA Si02
X=0.5
L Si02-PtxSn(l-x) (E [Pt] + [Sn] = 1.20 mmol HSA SiO2
X=0
M Si02-PtxSn(l-x) (F [Pt] + [Sn] = 1.20 mmol
HSA Si02
X=0.75
N Si02-PtxSn(i-x) (E [Pt] + [Sn] = 1.20 mmol HSA Si02
X=0.25
O SiO2-PtxSn(l-x) (F [Pt] + [Sn] 1.20 mmol
HSA SiO2
X=1
P 3 wt% Pt 1.8 wt% Sn 5 wt% CaSiO3 HSA Si02
Q 1 wt% Pt 1 wt% Sn CaSiO3
R 3 wt% Pt 1.8 n t% 10 wt % Ti02 HSA Si02?
S 3 wt% Pt 1.8 wt% W03 HSA SiO2
T 3 wt% Pt 1.8 wt% Pt H-ZSM-5
U Si02-RexPd(i-x) (F [Re] + [Pd] = 1.20 mmol HSA Si0
X=0.5 2
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Table 1
Catalyst Summary (cont.)
CP PGM Promoter other Support
V Si02-RexPd(l-x) (F [Re] + [Pd] = 1.20 mmol HSA Si0
2
X=0
W Si02-RexPd(l-x) (z [Re] + [Pd] = 1.20 mmol HSA Si02
X=.25
X Si02-RexPd(1-x) (Z [Re] + [Pd] = 1.20 mmol HSA Si02
X=.75
y Si02-RexPd(i-x) (z [Re] + [Pd] = 1.20 mmol HSA Si02
X=1
Z 1 mol% Pd 4. 5 mol% Re 5 wt% CaSiO3 HSA Si02?
AA 1.5%Pt 0.9% Sn 2.5%CaSiO3 Si02
BB 3%Pt 1.8%Sn 5%CaSiO3 Ti02
CC 3%-Pt 1.8% Sn KA160
DD 3%Pt 1.8% Sn. 8%CaSiO3 KA-160
AAA 2.5 wt% Pd 5 wt% Re CaSiO3
BBB 1wt%Pt 10 wt%Co HSASiO2
CCC 1 wt% Pt 10 wt% Co CaSiO3
DDD 1 wt% Pt 10wt% Co Zr02
Gas Chromatographic (GC) analysis of the Products
The analysis of the products was carried out by online GC. A three channel
compact GC equipped with one flame ionization detector (FID) and 2 thermal
conducting detectors (TCDs) was used to analyze the reactants and products.
The front channel was equipped with an FID and a CP-Sil 5 (20 m) + WaxFFap
(5 m) column and was used to quantify: Acetaldehyde; Ethanol; Acetone; Methyl
acetate; Vinyl acetate; Ethyl acetate; Acetic acid; Ethylene glycol diacetate;
Ethylene
glycol; Ethylidene diacetate; and Paraldehyde.
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The middle channel was equipped with a TCD and Porabond Qcolumn and
was used to quantify: C02; ethylene; and ethane.
The back channel was equipped with a TCD and Molsieve 5A column and was
used to quantify: Helium; Hydrogen; Nitrogen; Methane; and Carbon monoxide.
Prior to reactions, the retention time of the different components was
determined by spiking with individual compounds and the GCs were calibrated
either with a calibration gas of known composition or with liquid solutions of
known
compositions. This allowed the determination of the response factors for the
various components.
Example 1
In a tubular reactor made of stainless steel, having an internal diameter of
30 mm and capable of being raised to a controlled temperature, there are
arranged
50 mt of catalyst prepared as described in catalyst preparation C above. The
length
of the combined catalyst bed after charging was approximately about 70 mm.
The feed liquid was comprised essentially of acetic acid. The reaction feed
liquid was evaporated and charged to the reactor along with hydrogen and
helium
as a carrier gas with an average combined gas hourly space velocity (GHSV) of
2500 hr -1 at a temperature of 2502C and pressure of 100 psig. The feed stream
contained a mole percent of acetic acid from about 6.1% to about 7.3% and mole
percent of hydrogen from about 54.3% to about 61.5%. A portion of the vapor
effluent from the reactor was passed through a gas chromatograph for analysis
of
the contents of the effluents. The selectivity to ethanol was 93.4% at a
conversion of
acetic acid 85%.
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The catalyst utilized was 1 weight percent platinum and 1 weight percent tin
on silica prepared in accordance with the procedure of Catalyst Preparation A.
Example 2
The catalyst utilized was 1 weight percent platinum and 1 weight percent tin
on calcium silicate prepared in accordance with the procedure of Example C.
The procedure as set forth in Example 1 is substantially repeated with an
average combined gas hourly space velocity (GHSV) of 2,500 hr -1 of the feed
stream
of the vaporized acetic acid and hydrogen at a temperature of 2505?C and
pressure of
22 bar. A portion of the vapor effluent is passed through a gas chromatograph
for
analysis of the contents of the effluents. The acetic acid conversion is
greater than
70% and ethanol selectivity is 99%.
Comparative Example 1
The catalyst utilized was 1 weight percent tin on low surface area high purity
silica prepared in accordance with the procedure of Example E.
The procedure as set forth in Example 1 is substantially repeated with an
average combined gas hourly space velocity (GHSV) of 2,500 hr -1 of the feed
stream
of the vaporized acetic acid and hydrogen at a temperature of 2502C and
pressure of
22 bar. A portion of the vapor effluent is passed through a gas chromatograph
for
analysis of the contents of the effluents. The acetic acid conversion is less
than 10%
and ethanol selectivity is less than 1%.
Example 3
The procedure of Example 2 was repeated using a variety of catalysts at a
temperature as set forth in Table 2 setting forth the percentages of carbon
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monoxide (CO), acetaldehyde (AcH ) and ethane in the products as well as the
selectivity for, and productivity of, ethyl acetate (EtOAc); ethanol (EtOH) as
well as
the percentage conversion of acetic acid (HOAc) (MCD p. 4). Throughout, the
mole
ratio of H2 to acetic acid was maintained at 5:1. F or convenience, the
results of
examples 1 and 2 and comparative example 1 are also included in Table 2.
Generally
speaking when it is desired to produce ethanol as the primary product,,
selectivities
to ethanol above 80% or so are desirable; selectivities to ethyl acetate of
less than
5% are desired, preferably less than 3%.
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U
00
ro r, 0 C m tll al Ol
2 0
U
m l0 r- Ln N 00
0 Y ~ 00 N 00 0 r-I
r, r- LLU \ l0 N I ~-1 N
4A
d N
o r- 00 00 N N 0
W \ Ct N Ct r-I m m r-I
aA
0 rn I~t 00 00 0 m
4. Ln I- N m N N I.n
w
U
D c , r-I l0 N 0 N 0 N It
a-+ N I, l0 00 I-
w
N
v a)
a
m o a
1.0
w
I I I I I I
0 1 1 I 1 1 1
L
0 of
v Q o O o 0
N N N N N
aJ
I
0
0 Lr) t\ O 0 II II II
II 0 0 0 r-I II
II II II II X x X
X X
Ln x x X X X x ti ~a x
A '., x x x x '1 'a Ln a O 'a Ln
m C > 1 1 O_ N O. In O_ r,
+-+ Vx C C C C a) O 0) 0 a) O
U a N Ln V) to a) w cc
r-I r4
O_ N 0
0 0
0 N N N N (~
in 0 0 0 0 in cn cn
in in in in
~a z o > 3 x
CA 02778957 2012-04-25
WO 2011/056595 PCT/US2010/054134
U
Q
O CO 00Ln (n -q M r-i r-i
2 O
U
O O d N N 00 00)
r-I
W bbo
u J_-
Q 00 N to
bA N d= O N 0 ct I- N m
4 Ln to r1 ri m m r-I Ln 0
b0
00 0 m to
m N N Ln
W
U
O
O O rn N O N d' O O
l-- 0
w
N
_N N
W
rn
0
1 I I I 1 1
O of
41
U Q
N E
v
H
n m 1 n u n n 00
m x x x x r-1
4, a = X X X X c
-~ O o 00 00 -a Ln -0 0 -a Ln - 0
`'
a 0 c1 r4 fir) r4 a N a. tr) a N a 0 m
m O) ri x v O 0) O N O 4) .4
U oG N N N a) cr- cr- 1= Oa
O O I O 0 0 0 0
in N N N V) ul Q r-I
> 3 x u
u
CA 02778957 2012-04-25
WO 2011/056595 PCT/US2010/054134
v C
00
O c N
= O O O
U ++ m >}, +
o '>
V) Q ++ U
tiS
= S r1 LJ 0
t.0 -0
a) O
p . Lf) N
0) L-
` U
) +11 c4
V) m
4) "0
4J
C
O v
"- m E N o
Q L i
O l m E c LD
L to N
0. N V) E
v E V
o
LL-
4-1
Oo 00 N E V ¾ +'
L 0 O
C -0 I C 3 4J
a, 41 0
u 41 Q a N O
p 2 o V a,
0
L i1 U 0 4J
N 41 N y W
4J 41 "C Q Ch O
a w
C 3 +~ Ca V) v t
c v< m 0 to N N
= Uo U O o
m N _ ^ N"- 4)
Q 4
L -a c0 bA 0 > v
N X ~ 4J a1 p
0
O
U M0 U v N
V) 4~ W o 3 O V
E - m 0 0 ra
V) CL - 0 0 io ~v, -~ a~ .D v v
Q O O 1 - U C o 4J N
v E N N _u E U E 3 3 41
1- C v O M U
0 c a E 0 0 0 -u u
Q 3 o f 3 v
a U v 3= L v
>
O Ln CO 0= a? 0 v 2' u L o o
++
00 O +, v Q E V,
m V) U v c ' 6 v v u_ \an o 4- 0 0
0 V L v C O_
4- V)
0 0 +,
n3
Y a '~ c cco L) M
- -a c E
41 0 p 4, 0 a ca w w
a /Q~ a 1- E a- I- E F- F- 1- -.
U N m E V to l0 ..C N 10
u'i 0
r-I
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Example 4
Vaporized acetic acid and hydrogen were passed over a hydrogenation catalyst
of
the present invention comprising 2wt % Pt; and 2wt % Sn on high surface area
silica
(NPSG SS61138) having a surface area of approximately 250 m2/g at a ratio of
hydrogen to acetic acid of about 160 sccm/min H2: 0.09 g/min HOAc, the
hydrogen
being diluted with about 60 sccm/min N2 at a space velocity of about 6570 hr -
1 and a
pressure of 200 psig. The temperature was increased at about 50 hrs, 70 hrs
and
90hrs as indicated in Figures 1 and 2 wherein the productivity in grams of the
indicated products (ethanol, acetaldehyde, and ethyl acetate) per kilogram of
catalyst per hour are indicated in Figure 1 and the selectivity of a catalyst
for the
various products are indicated in Figure 2 with the upper line indicating
productivity
of or selectivity to ethyl acetate, the intermediate line indicating ethanol
and the
lower line indicating acetaldehyde. It is considered especially significant
that
production of, and selectivity for, acetaldehyde were low. The results are
summarized in the Data Summary below.
Data Summary
225 C 250 C 280 C 296 C
HOAc Conversion (%): 11.15 26.49 36.65 33.77
EtOH Productivity (g/kg/h): 187.65 380.59 517.62 434.67
EtOH Selectivity (wt%): 41.96 35.83 35.67 33.07
EtOAc Productivity (g/kg/h): 244.04 638.20 882.55 835.50
EtOAc Selectivity (wt%): 57.08 62.79 62.36 63.56
Example 5
The procedure as set forth in Example 1 was substantially repeated using a
catalyst having 2 wt.% Pt; 2 wt.% Sn supported on a catalyst comprising
pellets of
high surface area silica SS61138 from Saint-Gobain NorPro with an average
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combined gas hourly space velocity (GHSV) of 2500 hr-' of the feed stream of
vaporized acetic acid, hydrogen and helium at the indicated temperature set
forth in
table 2 and pressure of 100 psig. The resulting feed stream contained a mole
percent of acetic acid of about 7.3% and mole percent of hydrogen of about
54.3%.
A portion of the vapor effluent was passed through a gas chromatograph for
analysis
of the contents of the effluents. Results are as presented in Table 1.
Table 3
Catalyst Stability
2 wt% Pt/2 wt% Sn Catalyst "F"? supported on HSA SiO2
Reaction Temperature 225 C - 2962C; total TOS = 115 h.
225 C 250 C 280 C 296 C
HOAc 11.15 26.49 36.65 33.77
conversion %
EtOH
productivity 187.65 380.59 517.62 434.67
g/kg/h.
EtOH
selectivity wt. 41.96 35.83 35.67 33.07
EtOAc
productivity 244.04 638.20 8082.55 835.50
g/kg/h
EtOAc
selectivity wt. 57.08 62.79 62.36 63.56
The results of Example 5 are summarized in Figure 3, which demonstrates
that the relatively insensitivity of the catalyst to changes in temperature
makes this
catalyst well-suited for use in a so-called adiabatic reactor in which the
temperature
may vary substantially over the catalyst bed due to the low and uneven rate of
heat
removal from the reactor.
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Example 6
The influence of the [Sn]/[Pt] molar ratio in SiO2-PtxSn(l_x) catalysts was
studied by (i) varying the mol fraction of Pt at a constant metal loading
([Pt]+[Sn] _
1.20 mmol), and (ii) as a function of the reduction temperature. A distinct
maximum
at a Pt mol fraction of 0.5 (i.e., [Sn]/[Pt] = 1.0) was observed for both the
acetic acid
conversion, and the selectivity towards ethanol. The selectivity towards ethyl
acetate sharply changes at [Sn]/[Pt] = 1.0) in favor of ethanol. At a Pt mol
fraction of
either 25% or 75%, ethyl acetate is observed as the main product. The presence
of
an equimolar ratio of Pt and Sn appears to be preferable both for the increase
in
acetic acid conversion and the selectivity towards ethanol, c.f. Figures 4A-C.
Vaporized acetic acid (0.09 g/min HOAc) and hydrogen (160 sccm/min Hz; 60
sccm/min Ni) were passed over a hydrogenation catalyst of the present
invention
comprising Pt and Sn on high surface area silica having a surface area of
approximately 250 m2/g at a Temperature of = 2502C; GHSV = 6570 h-1; 12 h of
reaction time . In this example 6, the amount of metal (Pt + Sn) was
maintained
constant and the mass fraction of platinum was varied between 0 and 1. Figures
4A-
4C illustrate the selectivity, activity and productivity of the catalysts at
each. From
this example, it can be appreciated, that a maximum occurs in selectivity,
activity
and productivity when the mass fraction of platinum is approximately 0.5,
i.e., the
amount of platinum by weight is substantially equal to the amount of tin in
the
catalyst.
Example 7
Vaporized acetic acid and hydrogen were passed over a hydrogenation
catalyst of the present invention comprising 3wt % Pt, 1.5 wt % Sn and 5 wt %
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CaSiO3, as a promoter on high purity, high surface area silica having a
surface area of
approximately 250 m2/g at a molar ratio of hydrogen to acetic acid of about
5:1 at a
temperature of about 225 C. Figures 5A and 5B illustrate the selectivity, and
productivity of the catalysts as a function of time on-stream during the
initial portion
of the catalysts life. From the results of this example as reported in Figures
6A and
6B, it can be appreciated, that it is possible to attain a selectivity
activity of over 90%
and productivity of over 500 g of ethanol per kilogram of catalyst per hour.
Example 8
The procedure of Example 8 was repeated (same catalyst?) at a temperature
of about 250 C. Figures 7A- 7B illustrate the selectivity and productivity of
the
catalysts as a function of time on-stream during the initial portion of the
catalysts
life. From the results of this example, as reported in Figures 7A and 7B, it
can be
appreciated, that it is still possible to attain a selectivity activity of
over 90% but with
productivity of over 800 g of ethanol per kilogram of catalyst per hour at
this
temperature.
Example 9
To investigate the sensitivity of the temperature used for reduction of the
bimetallic platinum and tin precursors to the catalytic species, the influence
of the
reduction temperature was studied by activating the Pt/Sn optimized,
SiO2-(Pt05Sno55) catalyst, vide infra, in independent experiments from 225 to
500 C.
In four experiments, the material was activated at 280, 350, 425, and 500 C
under
flowing hydrogen for 4 hrs, followed by acetic acid reduction at a reaction
temperature of 250 C. (Catalyst activation was carried out using a 10 mol%
H2/N2
mixture (275 sccm/min) at ambient pressure using the following temperature
program: RT - Reduction Temp. (225 - 500 C), ramp 2 deg/min; hold for 4.0 hrs,
CA 02778957 2012-04-25
WO 2011/056595 PCT/US2010/054134
then lowered (or raised as necessary) to 250 C for HOAc reduction). In
addition, the
material activated at 225 C, was studied at a reaction temperature of both 225
and
250 C in the HOAc hydrogenation. No significant change of the selectivity
towards
ethanol and ethyl acetate was observed across the whole temperature range,
including for the catalyst activated at 225 C for both reaction temperatures,
225 and
250 C. Interestingly, a significant increase in the conversion (and
productivities) was
observed for the catalysts activated at lower, 225 and 280 C reduction
temperatures. A decrease in conversion at higher reduction temperatures may be
attributed to a sintering of metal particles. (See Figures 7A and 7B) Since no
change
in selectivity was observed, the composition of the metal particles (i.e.,
PtSn alloy)
appears to remain unchanged. The results of this Example are illustrated in
Figures
3 A-3C.
In these examples various other products including acetaldehyde, ethanol,
ethyl acetate, ethane, carbon monoxide, carbon dioxide, methane, isopropanol,
acetone and water were detected.
Example 10
The catalytic performance of a variety of catalysts was evaluated in the
catalytic
hydrogenation of acetic acid using 2.5 mt solid catalyst of the catalysts
indicated in
Table 4. In each case the catalyst particles had a size of 14/30 mesh, and
were
diluted 1:1 v/v with 14/30 mesh quartz chips. In each run the operating
pressure
was 200 psig (14 bar) with a feed rate of 0.09 g/min acetic acid; 120 sccm/min
of
hydrogen; 60 sccm/min nitrogen at a gross hourly space velocity of 6570 h-1
over s
span of 24 hr of time on stream (TOS). The results are as indicated in Table
4.
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CA 02778957 2012-04-25
WO 2011/056595 PCT/US2010/054134
Q C 0 00 .-1 0 0 m 0 N m N N It LO 0) 00 = o Ln CO N 1-1 c-1 Ln N 1-1 N N N N
N
O tL0
V ~.
v a`"i = Ln I:t ~o dv ~ 0
~ N ~r rn
pp 0 Z0 0) N N Ln m c-1 0 l0 0) N m In
W i-4 a--I c-1 r-I Ln c--I i-1 N .-1 N N
Q U dA
O O -S.- v
-0 W O Q c-I N `-i d' m w Ln N 00 00 lD
C r-1 Ln m oo a) Ln m c-I r-1
p 11 cn a 0 N m
W
Q O
O
C N E 0 N m L 00 N N 'IT N 000 00 00 om N
v v w
p0 E E L
O O N
m U
N y 0 m Ln lD N I-i i-1 I~ in
~.I
C W
U O *' C
m v c
(0 N t 4l t 00 N m
OJ M rj N W
41
r1 3
0 Q in Ln m N N r-i in N N
3 a
Lo
n N
OU v m v Ln
N
r-i =
v -a C7
in in 00 Ln in in in Ln Ln o Ln Ln Ln in
E N N It N N N N N N in 1N N N N
N C w 0 N N N (N N N N N N N N N N N
o L E I-
a LA E
C
G
N U
N 0 Ln
m O o
O lfl c
=r ~ N ~ O N
>
4~ C)
O> Ln Ln O O c N O r4 r4 r4
a o_ a o
> U E N a a ri
O
U -0 0 m o o a d O O i -* r4 0 N
(p - N O NO) in pc-1 c-I o ' rv rl a-+
.~..+ O ai 0.. c a u U O C In In d O_ d
T O O
O N N N N N N N (] N Ln o O O
O O O O O O O 4 4 `-1
f6 In Q O (i1 N N N in in cn + N Y~ O O
0
41 0 c 0 0 0 0 0 0 0 - o U U
N In l0 In '.0 in in in m Ln m m m
r\j r-4 r1i ~q r,4 r4 r14 O QI Q1 QI QI QI QI QI O QI 0
iz 05 On- LA
r. C3) 41 0
O Q a Z + N m M 0 n W M r" 04 o4 "t
W
V
CA 02778957 2012-04-25
WO 2011/056595 PCT/US2010/054134
U
aU E
a
0 c t\ ri U a)
0
Y }r
o .3
0
3: 0 a)
4l 00
O 1-1 00
> \ W 0) 0
tko 00 "0
U Y 0 U -
v U
O tin l.D lfl
0 W
= 0 E lp
0 ' N 0 OM II
Ln rl y
W
c V U T 'N
0 Ln cf -0 + Z
H w a) (0 ~_
0) W - u
d E
N O E
U ( u
U C , O
ar co
E
N it O 00 0
41 U m 2
E c
O
C 0 u M Q
0 a Q o E
3 v a
O C) f6
CO N C c
u v U
v Q o
~ 0 c O v x
0. O = o
Ln Ln Ln E -a c (0
E N r- a)
N N 0u E Q
~.... U ~.,,. U U
UD O
~~ ~, aJ 00
m
u E U
O p (0 <
fa
+ N 00 7 U
0 E Q
a) CL
..C Q - O
l U O cu aj -0 N a) V
__v cu V)
co
-, Q a) E 0)
1.0 (1) cu
O `'{ O O -0 c 0) -0
N a) OE
O
~ m p N .C ,N N
O N v O .-1
in 0 a) ' "' v; C > a) m U U U U E
-0 CL C 3 E f6 0
0
0 0 Oi u 0
Q
C bO 00 N U
c "t
C 0 Ln-1 1.0-i ^-1 I N I 7 0
W a O
Z ti 4- N cr ~ m v
In
CA 02778957 2012-04-25
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Example 11
Catalyst Stability: Si02-CaSiO3(5)-Pt(3)-Sn(1.8). The catalytic performance
and initial stability of Si02-CaSiO3(5)-Pt(3)-Sn(1.8) was evaluated at
constant
temperature (260 C) over 100 hrs of reaction time. Only small changes in
catalyst
performance and selectivity were observed over the 100 hrs of total reaction
time.
Acetaldehyde appears to be the only side product, its concentration (-3 wt%)
remained largely unchanged over the course of the experiment. A summary of
catalyst productivity and selectivity is provided in Figures 5A & 5B. The
influence of
the reaction temperature on product selectivity was studied in a separate
experiment over a total reaction time of 125 hours, vide supra.
Example 12
The Productivity and Selectivity of 3%Pt:1.5%Sn on High Purity High surface
area Si02 stabilized with 5% CaSiO3 in hydrogenation of acetic acid was
studied in a
run of 15 hours duration at 225 C using a fixed bed continuous reactor system
to
produce mainly acetaldehyde, ethanol, ethyl acetate through hydrogenation and
esterification reactions in a typical range of operating conditions employing
2.5 mi;
solid catalyst (14/30 mesh, diluted 1:1 (v/v, with quartz chips, 14/30 mesh);
at a
pressure of 200 psig; with a feed rate of 0.09 g/min HOAc; 160 sccm/min H2; 60
sccm/min N2; and GHSV = 6570 h"'. The results are set forth in Figures 6A and
6B.
Example 13
The Productivity and Selectivity of catalysts comprising Re and Pd in
SiO2 in which the molar ratio of RexPd(1_x) was modified between catalysts was
studied by varying the mol fraction of Re at a constant metal loading
([Pt]+[Sn] _
1.20 mmol) using 2.5 mL solid catalyst (14/30 mesh, diluted 1:1 (v/v, with
quartz
chips, 14/30 mesh); at a pressure of 200 psig (14 bar); feeding 0.09 g/min
acetic
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CA 02778957 2012-04-25
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acid; accompanied by 160 sccm/min hydrogen and ; 60 sccm/min nitrogen as a
diulent; at a temperature of 250 C; a GHSV = 6570 h-1; or 12 h of reaction
time.
While maximum conversion of acetic acid was observed at a Re mol fraction of
approximately 0.6, ethanol only becomes the main product at a Re mole fraction
of
approximately 0.78. At this molar ratio between Re and Pd (indicating
"Re7Pd2')
selectivity towards ethyl acetate narrowly changes in favor of ethanol.
Importantly,
and as shown for the Pd/Sn series above, the presence of a specific ratio of
the two
metals appears to be a key structural requirement for specific product
selectivity,
i.e., the selectivity shift towards ethanol at [Re]/[Re+Pd] = 0.78, c.f.
Figures 8, 9, and
10 presented in the same format as Figures 4A-C except that Xi(Re) represents
mass
fraction of rhenium in the catalyst. In contrast to the Pt/Sn materials,
however,
maximum conversion of acetic acid and selectivity towards ethanol do not
coincide
with these materials, and favorable selectivity towards ethanol is only
observed at
low HOAc conversions. Consequently, maximum productivities are seen for ethyl
acetate, rather than for ethanol, c.f., Figure 8. In addition, the formation
of
hydrocarbons (methane and ethane; 5.3 and 2.4 wt%, respectively) were observed
using a CaSiO3-Re(5)-Pd(2.5) catalyst at an acetic acid conversion of about 30
% and
a reaction temperature of only 225 C. Although a higher conversion of acetic
acid
can most likely be obtained by increasing the reaction temperature, the
amounts of
hydrocarbons will likely increase as well, thus limiting the overall
efficiency of a
Re/Pd-based catalytic system.
Example 14
Initial catalyst screening using a silica-supported platinum (1%) cobalt
catalyst (Co loading 10 wt%) on Si02 resulted in high acetic acid conversion
and
about 80% selectivity towards ethanol. See Figures 11 and 12 in which
selectivity
and activity are as defined previously with the results for ethanol being
represented
CA 02778957 2012-04-25
WO 2011/056595 PCT/US2010/054134
by squares, results for ethyl acetate being represented by circles,
acetaldehyde by
diamonds and ethane by triangles. It appears, however, that the catalyst
degrades
as the acetic acid selectivity declined from about 80 % to 42% over the course
of
nine hours of reaction time. In addition, significant changes in productivity
are
observed as well, and declining ethanol selectivity was accompanied with an
increase in the selectivity towards ethyl acetate and acetaldehyde. Similar
results
are obtained with 10% cobalt supported on Silica.
Example 15
Vaporized acetic acid (0.09 g/min HOAc) and hydrogen (160 sccm/min H2; 60
sccm/min N2) at a pressure of 200 psig were passed over a hydrogenation
catalyst of
the present invention comprising 3wt% Pt and 1.8wt% Sn on a support comprising
hydrogen form ZSM-5 molecular sieve at a Temperature of = 2505?C; GHSV = 6570
h-1;
12 h of reaction time. Diethyl ether was obtained at a selectivity of 96% and
a
productivity of 2646 g/kg/h accompanied by 4% ethyl acetate with 78% acetic
acid
remaining unreacted.
Example 16
Vaporized acetic acid (0.09 g/min HOAc) and hydrogen (160 sccm/min H2; 60
sccm/min N2) at
a pressure of 200 psig were passed over a hydrogenation catalyst of the
present
invention comprising 2wt% Pt and lwt% Sn on a support comprising high surface
area graphite at 275 C; GHSV = 6570 h-1; 12 h of reaction time. The
selectivity to ethyl
acetate was 43%, the selectivity to ethanol 57%, the productivity of ethyl
acetate
was 66 g/kg/hr, the productivity of ethanol was 88 g/kg/hr and the conversion
of
acetic acid was 12%.
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While the invention has been described in detail, modifications within
the spirit and scope of the invention will be readily apparent to those of
skill in the
art. In view of the foregoing discussion, relevant knowledge in the art and
references discussed above in connection with the Background and Detailed
Description, the disclosures of which are all incorporated herein by
reference,
further exemplification is deemed unnecessary. In addition, it should be
understood that aspects of the invention and portions of various embodiments
and
various features recited below and/or in the appended claims may be combined
or
interchanged either in whole or in part. Furthermore, those of ordinary skill
in the
art will appreciate that the foregoing description is by way of example only,
and is
not intended to limit the invention.
There is thus provided in accordance with the present invention, novel
processes and catalysts for providing hydrogenated products based on acetic
acid.
Embodiment #1, for example is a process for production of ethanol by
reduction of acetic acid comprising passing a gaseous stream comprising
hydrogen
and acetic acid in the vapor phase in a mole ratio of hydrogen to acetic acid
of at
least about 4:1 at a temperature of between about 225 C and 300 C over a
hydrogenation catalyst comprising platinum and tin dispersed on a silicaceous
support wherein the amounts and oxidation states of the platinum and tin, as
well
as the ratio of platinum to tin, and the silicaceous support are selected,
composed
and controlled such that: (i) at least 80% of the acetic acid converted is
converted to
ethanol; (ii) less than 4% of the acetic acid is converted to compounds other
than
compounds chosen from the group consisting of ethanol, acetaldehyde, ethyl
acetate, ethylene and mixtures thereof; and the activity of the catalyst
declines by
less than 10% when exposed to a vaporous mixture of acetic acid and hydrogen
at a
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molar ratio of 10:1 at a pressure of 2 atm and a temperature of 275 C and a
GHSV of
2500 hr-1 for a period of 168 hours.
Embodiment #2 is the process of embodiment #1, wherein the
hydrogenation catalyst consists essentially of platinum and tin dispersed on
the
silicaceous support and the silicaceous support is a modified silicaceous
support,
said modified silicaceous support including an effective amount of a support
modifier selected from the group consisting of: (i) alkaline earth oxides,
(ii) alkali
metal oxides, (iii) alkaline earth metasilicates, (iv) alkali metal
metasilicates, (v) zinc
oxide , (vi) zinc metasilicate and (vii) precursors for any of (i)-(vi), and
mixtures of
any of (i)-(vii).
Embodiment #3, is a process of embodiment #2, wherein the support
modifier is chosen from the group consisting of oxides and metasilicates of
sodium,
potassium, magnesium, calcium, and zinc as well as precursors therefor and
mixtures of any of the foregoing.
Embodiment #4 is a process of embodiment #2, wherein (a) platinum is
present in an amount of 0.5 % to 5% of the weight of the catalyst; and (b) tin
is
present in an amount of at least 0.5 to 10%.
Embodiment #5 is a process of embodiment #3, wherein the molar ratio of
platinum to tin is between 4:5 and 5:4.
Embodiment #6 is a process of embodiment #2, wherein the support
modifier is chosen from the group consisting of metasilicates of sodium,
potassium,
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magnesium, calcium, and zinc as well as precursors therefor and mixtures of
any of
the foregoing.
Embodiment #7 is a process of embodiment #5, wherein (a) platinum is
present in an amount of 0.5 % to 5% of the weight of the catalyst; and (b) tin
is
present in an amount of at least 0.5 to 10%.
Embodiment #8 is a process of embodiment #6, wherein the molar ratio of
platinum to tin is between 4:5 and 5:4.
Embodiment #9 is a process of embodiment #2, wherein the support
modifier is chosen from the group consisting of oxides and metasilicates of
magnesium, calcium, and zinc as well as precursors therefor and mixtures of
any of
the foregoing.
Embodiment #10 is a process of embodiment #9, wherein: (a) platinum is
present in an amount of 0.5 % to 5% of the weight of the catalyst; and (b) tin
is
present in an amount of at least 0.5 to 10%.
Embodiment #11 is a process of embodiment #10, wherein the molar ratio of
platinum to tin is between 4:5 and 5:4.
Embodiment #12 is a process of embodiment #2, wherein the support
modifier is chosen from the group consisting of metasilicates of magnesium,
calcium, and zinc as well as precursors therefor and mixtures of any of the
foregoing.
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Embodiment #13 is a process of embodiment #12, wherein (a) platinum is
present in an amount of 0.5 % to 5% of the weight of the catalyst; and (b) tin
is
present in an amount of at least 0.5 to 10%.
Embodiment #14 is a process of embodiment #12, wherein the molar ratio of
platinum to tin is between 4:5 and 5:4.
Embodiment #15 is a process of embodiment #2, wherein the support
modifier is chosen from the group consisting of calcium metasilicate,
precursors for
calcium metasilicate and mixtures of calcium metasilicate and precursors
therefor.
Embodiment #16 is a process of embodiment #15, wherein (a) platinum is
present in an amount of 0.5 % to 5% of the weight of the catalyst; and (b) tin
is
present in an amount of at least 0.5 to 10%.
Embodiment #17 is a process of embodiment #16, wherein the molar ratio of
platinum to tin is between 4:5 and 5:4.
Embodiment #18 s a process of embodiment #2, wherein (a) platinum is
present in an amount of 0.5 % to 5% of the weight of the catalyst; and (b) tin
is
present in an amount of at least 0.5 to 10%.
Embodiment #19 is a process of embodiment #16, wherein the molar ratio of
platinum to tin is between 4:5 and 5:4.
Embodiment #20 is a process of embodiment #18, wherein the surface area
of the support is at least about 100 m2/g.
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Embodiment #21 is a process of embodiment #20 wherein the mole ratio of
tin to platinum group metal is from about 1:2 to about 2:1.
Embodiment #22 is a process of embodiment #20 wherein the mole ratio of
tin to platinum is from about 2:3 to about 3:2.
Embodiment #23 is a process of embodiment #20 wherein the weight ratio
of tin to platinum is from about 5:4 to about 4:5.
Embodiment #24 is a process of embodiment #2, wherein the surface area of
the support is at least about 150 m2/g.
Embodiment #25 is a process of embodiment #24, wherein (a) platinum is
present in an amount of 0.5 % to 5% of the weight of the catalyst; and (b) tin
is
present in an amount of at least 0.5 to 5%.
Embodiment #26 is a process of embodiment #24, wherein the support
comprises from at least about 1% to about 10% by weight of calcium silicate.
Embodiment #27 is a process of embodiment #24, wherein the mole ratio of
tin to platinum is from about 1:2 to about 2:1.
Embodiment #28 is a process of embodiment #24, wherein the mole ratio of
tin to platinum is from about 2:3 to about 3:2.
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Embodiment #29 is a process of embodiment #24, wherein the weight ratio
of tin to platinum is from about 5:4 to about 4:5.
Embodiment #30 is a process of embodiment #2, wherein the surface area of
the support is at least about 200 m2/g.
Embodiment #31 is a process of embodiment #30, wherein the mole ratio of
tin to platinum is from about 2:3 to about 3:2.
Embodiment #32 is a process of embodiment #30, wherein the mole ratio of
tin to platinum is from about 5:4 to about 4:5.
Embodiment #33 is a process of embodiment #30, wherein the mole ratio of
tin to platinum is from about 9:10 to about 10:9.
Embodiment #34 is a process of embodiment #33, wherein the surface area
of the modified silicaceous support is at least about 250 m2/g.
Embodiment #35 is a process of embodiment #2, conducted at a
temperature of between about 250 C and 300 C, wherein (a) the surface area of
the
modified silicaceous support is at least about 250 m2/g; (b) platinum is
present in
the hydrogenation catalyst in an amount of at least about 0.75% by weight; (c)
the
mole ratio of tin to platinum is from about 5:4 to about 4:5; and (d) the
modified
silicaceous support comprises silica having a purity of at least about 95%
modified
with from at least about 2.5% to about 10% by weight of calcium metasilicate.
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Embodiment #36 is a process of embodiment #35, wherein the amount of
platinum present is at least 1% by weight.
Embodiment #37 is a process of embodiment #2, conducted at a
temperature of between about 250 C and 300 C, wherein (a) the surface area of
the
modified silicaceous support is at least about 100 g/m; (b) wherein the mole
ratio of
tin to platinum is from about 2:3 to about 3:2; and (c) the modified
silicaceous
support comprises silica having a purity of at least about 95% modified with
from at
least about 2.5% to about 10% by weight of calcium metasilicate.
Embodiment #38 is a process of embodiment #37, wherein the amount of
platinum present is at least 0.75% by weight.
Embodiment #39 is a process of embodiment #38, wherein the catalyst
occupies a reactor volume and the gaseous stream comprising hydrogen and
acetic
acid in the vapor phase is passed through said reactor volume at a space
velocity of
at least about 1000 hr 1.
Embodiment #40 is a process of embodiment #38, wherein the catalyst
occupies a reactor volume and the gaseous stream comprising hydrogen and
acetic
acid in the vapor phase is passed through said reactor volume at a space
velocity of
at least about 2500 hr 1.
Embodiment #41 is a process of embodiment #40, wherein the amounts and
oxidation states of the platinum and tin, as well as the ratio of platinum to
tin and
the modified silicaceous support are controlled such that: (i) at least 90% of
the
acetic acid converted is converted to ethanol: (ii) less than 2% of the acetic
acid is
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converted to compounds other than compounds chosen from the group consisting
of ethanol, acetaldehyde, ethyl acetate, and ethylene and mixtures thereof;
and (III)
and the activity of the catalyst declines by less than 10% when exposed to a
vaporous mixture of acetic acid and hydrogen at a molar ratio of 10:1 at a
pressure
of 2 atm and a temperature of 275 C and a GHSV of 2500 hr-1 for a period of
336
hours.
Embodiment #42 is a process of embodiment #38, wherein the catalyst
occupies a reactor volume and the gaseous stream comprising hydrogen and
acetic
acid in the vapor phase is passed through said reactor volume at a space
velocity of
at least about 5000 hr 1.
Embodiment #43 is a process of embodiment #42, wherein the amounts and
oxidation states of the platinum and tin, as well as the ratio of platinum to
tin and
the modified silicaceous support are controlled such that: (i) at least 90% of
the
acetic acid converted is converted to ethanol; (ii) less than 2% of the acetic
acid is
converted to alkanes; (iii) the activity of the catalyst declines by less than
10% when
exposed to a vaporous mixture of acetic acid and hydrogen at a molar ratio of
10:1
at a pressure of 2 atm and a temperature of 275 C at a GHSV of 2500 hr -1 for
a
period of 168 hours.
Embodiment #44 is a process of embodiment #43, conducted at a
temperature of between about 250 C and 300 C, wherein (a) the surface area of
the
modified silicaceous support is at least about 200 m2/g; (b) the mole ratio of
tin to
platinum is from about 5:4 to about 4:5;(c) the modified silicaceous support
comprises silica having a purity of at least about 95% and the modifier
comprises
from at least about 2.5% to about 10% by weight of calcium silicate.
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Embodiment #45 is a process for production of ethanol by reduction of acetic
acid comprising passing a gaseous stream comprising hydrogen and acetic acid
in the
vapor phase in a mole ratio of hydrogen to acetic acid of at least about 4:1
at a
temperature of between about 225 C and 300 C over a hydrogenation catalyst
comprising platinum and tin dispersed on an oxidic support wherein the amounts
and oxidation states of the platinum and tin, as well as the ratio of platinum
to tin,
and the oxidic support are selected, composed and controlled such that: (i) at
least
80% of the acetic acid converted is converted to ethanol; (ii) less than 4% of
the
acetic acid is converted to compounds other than compounds chosen from the
group consisting of ethanol, acetaldehyde, ethyl acetate, ethylene and
mixtures
thereof; and the activity of the catalyst declines by less than 10% when
exposed to a
vaporous mixture of acetic acid and hydrogen at a molar ratio of 10:1 at a
pressure
of 2 atm and a temperature of 275 C and a GHSV of 2500 hr' for a period of 500
hours.
Embodiment #46 is a process of embodiment #45, wherein the
hydrogenation catalyst consists essentially of platinum and tin dispersed on
the
oxidic support and the oxidic support is a modified oxidic support, said
modified
oxidic support including an effective amount of a support modifier selected
from the
group consisting of: (i) alkaline earth oxides, (ii) alkali metal oxides,
(iii) alkaline earth
metasilicates, (iv) alkali metal metasilicates, (v) zinc oxide , (vi) zinc
metasilicate and
(vii) precursors for any of (i)-(vi), and mixtures of any of (i)-(vii).
Embodiment #47 is a process of embodiment #46, wherein the support
modifier is chosen from the group consisting of oxides and metasilicates of
sodium,
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potassium, magnesium, calcium, and zinc as well as precursors therefor and
mixtures of any of the foregoing.
Embodiment #48 is a process of embodiment #47, wherein (a) platinum is
present in an amount of 0.5 % to 5% of the weight of the catalyst; and (b) tin
is
present in an amount of at least 0.5 to 10%.
Embodiment #49 is a process of embodiment #47, wherein the molar ratio of
platinum to tin is between 4:5 and 5:4.
Embodiment #50 is a process of embodiment #46, wherein the support
modifier is chosen from the group consisting of metasilicates of sodium,
potassium,
magnesium, calcium, and zinc as well as precursors therefor and mixtures of
any of
the foregoing.
Embodiment #51 is a process of embodiment #50, wherein (a) platinum is
present in an amount of 0.5 % to 5% of the weight of the catalyst; and (b) tin
is
present in an amount of at least 0.5 to 10%.
Embodiment #52 is a process of embodiment #51 wherein the molar ratio of
platinum to tin is between 4:5 and 5:4.
Embodiment #53 is a process of embodiment #46, wherein the support
modifier is chosen from the group consisting of oxides and metasilicates of
magnesium, calcium, and zinc as well as precursors therefor and mixtures of
any of
the foregoing.
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Embodiment #54 is a process of embodiment #53, wherein (a) platinum is
present in an amount of 0.5 % to 5% of the weight of the catalyst; and (b) tin
is
present in an amount of at least 0.5 to 10%.
Embodiment #55 is a process of embodiment #54, wherein the molar ratio of
platinum to tin is between 4:5 and 5:4.
Embodiment #56 is a process of embodiment #46, wherein the support
modifier is chosen from the group consisting of metasilicates of magnesium,
calcium, and zinc as well as precursors therefor and mixtures of any of the
foregoing.
Embodiment #57 is a process of embodiment #56, wherein (a) platinum is
present in an amount of 0.5 % to 5% of the weight of the catalyst; and (b) tin
is
present in an amount of at least 0.5 to 10%.
Embodiment #58 is a process of embodiment #57, wherein the molar ratio of
platinum to tin is between 4:5 and 5:4.
Embodiment #59 is a process of embodiment #46, wherein the support
modifier is chosen from the group consisting of calcium metasilicate,
precursors for
calcium metasilicate and mixtures of calcium metasilicate and precursors
therefor.
Embodiment #60 is a process of embodiment #59, wherein (a) platinum is
present in an amount of 0.5 % to 5% of the weight of the catalyst; and (b) tin
is
present in an amount of at least 0.5 to 10%.
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Embodiment #61 is a process of embodiment #60, wherein the molar ratio of
platinum to tin is between 4:5 and 5:4.
Embodiment #62 is a process of embodiment #46, wherein (a) platinum is
present in an amount of 0.5 % to 5% of the weight of the catalyst; and (b) tin
is
present in an amount of at least 0.5 to 10%.
Embodiment #63 is a process of embodiment #62, wherein the molar ratio of
platinum to tin is between 4:5 and 5:4.
Embodiment #64 is a process of embodiment #62, wherein the surface area
of the support is at least about 100 m2/g.
Embodiment #65 is a process of embodiment #64, wherein the mole ratio of
tin to platinum group metal is from about 1:2 to about 2:1.
Embodiment #66 is a process of embodiment #64 wherein the mole ratio of
tin to platinum is from about 2:3 to about 3:2.
Embodiment #67 is a process of embodiment #64 wherein the weight ratio
of tin to platinum is from about 5:4 to about 4:5.
Embodiment #68 is a process of embodiment #46, wherein the surface area
of the support is at least about 150 m2/g.
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Embodiment #69 is a process of embodiment #68, wherein (a) platinum is
present in an amount of 0.5 % to 5% of the weight of the catalyst; and (b) tin
is
present in an amount of at least 0.5 to 5%.
Embodiment #70 is a process of embodiment #68, wherein the support
comprises from at least about 1% to about 10% by weight of calcium silicate.
Embodiment #71 is a process of embodiment #68, wherein the mole ratio of
tin to platinum is from about 1:2 to about 2:1.
Embodiment #72 is a process of embodiment #68, wherein the mole ratio of
tin to platinum is from about 2:3 to about 3:2.
Embodiment #73 is a process of embodiment #68, wherein the weight ratio
of tin to platinum is from about 5:4 to about 4:5.
Embodiment #74 is a process of embodiment #46, wherein the surface area
of the support is at least about 200 m2/g.
Embodiment #75 is a process of embodiment #74, wherein the mole ratio of
tin to platinum is from about 2:3 to about 3:2.
Embodiment #76 is a process of embodiment #74, wherein the mole ratio of
tin to platinum is from about 5:4 to about 4:5.
Embodiment #77 is a process of embodiment #74, wherein the mole ratio of
tin to platinum is from about 9:10 to about 10:9.
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Embodiment #78 is a process for production of ethanol by reduction of acetic
acid comprising passing a gaseous stream comprising hydrogen and acetic acid
in the
vapor phase in a mole ratio of hydrogen to acetic acid of at least about 4:1
at a
temperature of between about 225 C and 300 C over a hydrogenation catalyst
consisting essentially of platinum and tin dispersed on a modified stabilized
silicaceous support, the modified stabilized silicaceous support comprising
silica
having a purity of at least about 95% by weight modified with an stabilizer-
modifier
chosen from the group consisting of (i) alkaline earth oxides, (ii) alkali
metal oxides,
(iii) alkaline earth metasilicates, (iv) alkali metal metasilicates, (v) zinc
oxide , (vi) zinc
metasilicate and (vii) precursors for any of (i)-(vi), and mixtures of any of
(i)-(vii),
wherein the amounts and oxidation states of the platinum and tin, the ratio of
platinum to tin and the relative proportions of stabilizer-modifier to silica
in the
modified stabilized silicaceous support as well as the purity of the silica in
the
modified stabilized silicaceous support are controlled such that at least 80%
of the
acetic acid converted is converted to ethanol and less than 4% of the acetic
acid is
converted to compounds other than compounds chosen from the group consisting
of ethanol, acetaldehyde, ethyl acetate, ethylene and mixtures thereof.
Embodiment #79 is a process of embodiment #78, wherein (a) platinum is
present in an amount of 0.5 % to 5% of the weight of the catalyst; and (b) tin
is
present in an amount of at least 0.5 to 10%.
Embodiment #80 is a process of embodiment #79, wherein the surface area
of the modified stabilized silicaceous support is at least about 100 m2/g.
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Embodiment #81 is a process of embodiment #80, wherein the mole ratio of
tin to platinum group metal is from about 1:2 to about 2:1.
Embodiment #82 is a process of embodiment #80, wherein the mole ratio of
tin to platinum is from about 2:3 to about 3:2.
Embodiment #83 is a process of embodiment #79, wherein the weight ratio
of tin to platinum is from about 5:4 to about 4:5.
Embodiment #84 is a process of embodiment #78, wherein the surface area
of the modified stabilized silicaceous support is at least about 150 mz/g.
Embodiment #85 is a process of embodiment #84, wherein (a) platinum is
present in an amount of 0.5 % to 5% of the weight of the catalyst; and (b) tin
is
present in an amount of at least 0.5 to 5%.
Embodiment #86 is a process of embodiment #84, wherein the modified
stabilized silicaceous support comprises from at least about 1% to about 10%
by
weight of calcium silicate.
Embodiment #87 is a process of embodiment #84, wherein the mole ratio of
tin to platinum is from about 1:2 to about 2:1.
Embodiment #88 is a process of embodiment #84, wherein the mole ratio of
tin to platinum is from about 2:3 to about 3:2.
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Embodiment #89 is a process of embodiment #84, wherein the weight ratio
of tin to platinum is from about 5:4 to about 4:5.
Embodiment #90 is a process of embodiment #87, wherein the surface area
of the modified stabilized silicaceous support is at least about 200 m2/g.
Embodiment #91 is a process of embodiment #90, wherein the mole ratio of
tin to platinum is from about 9:10 to about 10:9.
Embodiment #92 is a process of embodiment #90, wherein the mole ratio of
tin to platinum is from about 2:3 to about 3:2.
Embodiment #93 is a process of embodiment #90, wherein the mole ratio of
tin to platinum is from about 5:4 to about 4:5.
Embodiment #94 is a process of embodiment #90, wherein the surface area
of the modified stabilized silicaceous support is at least about 250 m2/g.
Embodiment #95 is a process of embodiment #78, conducted at a
temperature of between about 250 C and 300 C, wherein (a) the surface area of
the
modified stabilized silicaceous support is at least about 250 m2/g; (b)
platinum is
present in the hydrogenation catalyst in an amount of at least about 0.75% by
weight; (c) the mole ratio of tin to platinum is from about 5:4 to about 4:5;
and (d)
the modified stabilized silicaceous support comprises from at least about 2.5%
to
about 10% by weight of calcium silicate.
Embodiment #96 is a process of embodiment #95, wherein the amount of
platinum present is at least 1% by weight.
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Embodiment #97 is a process of embodiment #78 conducted at a
temperature of between about 250 C and 300 C, wherein (a) the surface area of
the
modified stabilized silicaceous support is at least about 100 g/m; (b) wherein
the
mole ratio of tin to platinum is from about 2:3 to about 3:2; and (c) the
modified
stabilized silicaceous support comprises from at least about 2.5% to about 10%
by
weight of calcium silicate.
Embodiment #98 is a process of embodiment #97, wherein the amount of
platinum present is at least 0.75% by weight.
Embodiment #99 is a process of embodiment #98, wherein the catalyst
occupies a reactor volume and the gaseous stream comprising hydrogen and
acetic
acid in the vapor phase is passed through said reactor volume at a space
velocity of
at least about 1000 hr 1.
Embodiment #100 is a process of embodiment #98, wherein the catalyst
occupies a reactor volume and the gaseous stream comprising hydrogen and
acetic
acid in the vapor phase is passed through said reactor volume at a space
velocity of
at least about 2500 hr-'.
Embodiment #101 is a process of embodiment #100, wherein the amounts
and oxidation states of the platinum and tin, as well as the ratio of platinum
to tin
and the composition of the modified stabilized silicaceous support are
controlled
such that at least 90% of the acetic acid converted is converted to ethanol
and less
than 2% of the acetic acid is converted to compounds other than compounds
chosen
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from the group consisting of ethanol, acetaldehyde, ethyl acetate, and
ethylene and
mixtures thereof.
Embodiment #102 is a process of embodiment #98, wherein the catalyst
occupies a reactor volume and the gaseous stream comprising hydrogen and
acetic
acid in the vapor phase is passed through said reactor volume at a space
velocity of
at least about 5000 hr 1.
Embodiment #103 is a process of embodiment #79, wherein the amounts
and oxidation states of the platinum and tin, as well as the ratio of platinum
to tin
and the composition of the modified stabilized silicaceous support are
controlled
such that at least 90% of the acetic acid converted is converted to ethanol
and less
than 2% of the acetic acid is converted to alkanes.
Embodiment #104 is a process of embodiment #79, conducted at a
temperature of between about 250 C and 300 C, wherein (a) wherein the amounts
and oxidation states of the platinum and tin, as well as the ratio of platinum
to tin
and the acidity of the modified stabilized silicaceous support are controlled
such that
at least 90% of the acetic acid converted is converted to ethanol and less
than 1% of
the acetic acid is converted to alkanes; (b) the surface area of the modified
stabilized
silicaceous support is at least about 200 m2/g; (c) the mole ratio of tin to
platinum is
from about 5:4 to about 4:5; (d) the modified stabilized silicaceous support
comprises from at least about 2.5% to about 10% by weight of calcium silicate.
Embodiment #105 is a process for production of ethanol by reduction of
acetic acid comprising passing a gaseous stream comprising hydrogen and acetic
acid in the vapor phase in a mole ratio of hydrogen to acetic acid of at least
about
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4:1 at a temperature of between about 225 C and 300 C over a hydrogenation
catalyst consisting essentially of: a catalytic metal chosen from the group
consisting
of : Fe, Co, Cu, Ni, Ru, Rh, Pd, Ir, Pt, Sn, Re, Os, Ti, Zn, Cr, Mo and W as
well as
mixtures thereof in an amount of from about 0.1% to about 10% by weight; and
an
optional promoter, dispersed on a suitable support wherein the amounts and
oxidation states of the catalytic metal(s) and the compositions of the support
and
optional promoter as well as reaction conditions are controlled such that: (i)
at least
80% of the acetic acid converted is converted to ethanol; (ii) less than 4% of
the
acetic acid is converted to compounds other than compounds chosen from the
group consisting of ethanol, acetaldehyde, ethyl acetate, ethylene, diethyl
ether and
mixtures thereof; and the activity of the catalyst declines by less than 10%
when
exposed to a vaporous mixture of acetic acid and hydrogen at a molar ratio of
10:1
at a pressure of 2 atm and a temperature of 275 C and a GHSV of 2500 hr -1 for
a
period of 500 hours.
Embodiment #106 is a process of embodiment #105, wherein the support is
an oxidic support modified with a modifier selected from the group consisting
of
oxides and metasilicates of sodium, potassium, magnesium, calcium, scandium,
yttrium and zinc as well as precursors therefor and mixtures of any of the
foregoing.
Embodiment #107 is a process of embodiment #105, wherein the support is
a carbon support and the catalytic metals include platinum and tin.
Embodiment #108 is a process of embodiment #107, wherein the carbon
support is modified with a reducible metal oxide.
Embodiment #109 is a process for production of ethanol by reduction of
acetic acid comprising passing a gaseous stream comprising hydrogen and acetic
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acid in the vapor phase in a mole ratio of hydrogen to acetic acid of at least
about
4:1 at a temperature of between about 225 C and 300 C over a hydrogenation
catalyst consisting essentially of metallic components dispersed on an oxidic
support, said hydrogenation catalyst having the composition:
PtõPd,õRexSnyAIZCaPSigOr,
wherein v and y are between 3:2 and 2:3; w and x are between 1:3 and 1:5,
wherein
p and z and the relative locations of aluminum and calcium atoms present are
controlled such that Bronsted acid sites present upon the surface thereof are
counteracted by calcium silicate; p and q are selected such that p:q is from
1:20 to
1:200 with r being selected to satisfy valence requirements and v and w are
selected
such that
_ (3.2'.-v 17s 0.005< 0.05.
q
Embodiment #110 is a process of embodiment #109, wherein the
hydrogenation catalyst has a surface area of at least about 100 m2/g and
wherein z
and p are controlled such that p ? z.
Embodiment #111 is a process of embodiment #110, wherein p is selected, in
view of any minor impurities present, to ensure that the surface of the
support is
essentially free of Bronsted acid sites.
Embodiment #112 is a process for hydrogenating acetic acid comprising
passing a gaseous stream comprising hydrogen and acetic acid in the vapor
phase in
a mole ratio of hydrogen to acetic acid of at least about 4:1 at a temperature
of
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between about 225 C and 300 C over a hydrogenation catalyst consisting
essentially
of: a catalytic metal chosen from the group consisting of : Fe, Co, Cu, Ni,
Ru, Rh, Pd,
Ir, Pt, Sn, Re, Os, Ti, Zn, Cr, Mo and W as well as mixtures thereof in an
amount of
from about 0.1% to about 10% by weight; and an optional promoter, dispersed on
a
suitable support wherein the amounts and oxidation states of the catalytic
metal(s)
and the compositions of the support and optional promoter as well as reaction
conditions are controlled such that less than 4% of the acetic acid is
converted to
compounds other than compounds chosen from the group consisting of ethanol,
acetaldehyde, ethyl acetate, ethylene, diethyl ether and mixtures thereof; and
the
activity of the catalyst declines by less than 10% when exposed to a vaporous
mixture of acetic acid and hydrogen at a molar ratio of 10:1 at a pressure of
2 atm
and a temperature of 275 C and a GHSV of 2500 hr -1 for a period of 500 hours,
with
the further provisos: (i) wherein the support is an oxidic support modified
with a
modifier selected from the group consisting of oxides and metasilicates of
sodium,
potassium, magnesium, calcium, scandium, yttrium and zinc as well as
precursors
therefor and mixtures of any of the foregoing; (ii) the support is a carbon
support
and the catalytic metals include platinum and tin or (iii) the support is a
carbon
support modified with a reducible metal oxide.
Embodiment #113 is a process for hydrogenating alkanoic acids comprising
passing a gaseous stream comprising hydrogen and an alkanoic acid in the vapor
phase in a mole ratio of hydrogen to alkanoic acid of at least about 2:1 at a
temperature of between about 125 C and 350 C over a hydrogenation catalyst
comprising: a platinum group metal chosen from the group consisting of
platinum,
palladium, rhenium and mixtures thereof on a silicaceous support chosen from
the
group consisting of silica, calcium metasilicate and calcium metasilicate
promoted
silica; and a promoter chosen the group consisting of tin, rhenium and
mixtures
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thereof, the silicaceous support being optionally promoted with a promoter
chosen
from the group consisting of (a) a promoter chosen from the group consisting
of
alkali metals; alkaline earth elements and zinc in an amount of 1 to 5% by
weight of
the catalyst; (b) a redox promoter chosen from the group consisting of: W03;
MoO3i
Fe2O3 and Cr2O3 in an amount of 1 to 50% by weight of the catalyst; and (c) an
acidic
modifier chosen from the group consisting of Ti02; ZrO2; Nb205; Ta205; and
A1203 in
an amount of 1 to 50% by weight of the catalyst.
Embodiment #114 is a process of embodiment # 113, wherein said alkanoic
acid is acetic acid, and wherein (a) at least one of platinum and palladium is
present
in an amount of 0.25 % to 5% of the weight of the catalyst; (b) the combined
amount
of platinum and palladium present is at least 0.5% by weight of catalyst; and
(c) the
combined amount of rhenium and tin present is at least 0.5 to 10% by weight.
Embodiment #115 is a process of embodiment # 114, wherein the surface
area of the silicaceous support is at least about 150 m2/g.
Embodiment #116 is a process of embodiment # 115, wherein (a) the
amounts and oxidation states of the platinum group metals, the rhenium and tin
promoters, as well as (b) the mole ratio of platinum group metal to combined
moles
of rhenium and tin present; and (c) the number of Bronsted acid sites on the
silicaceous support are controlled such that at least 80% of the acetic acid
converted
is converted to a compound chosen from the group consisting of ethanol and
ethyl
acetate while less than 4% of the acetic acid is converted to compounds other
than
compounds chosen from the group consisting of ethanol, acetaldehyde, ethyl
acetate, ethylene and mixtures thereof.
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Embodiment #117 is a process of embodiment # 115, wherein (a) at least one
of platinum and palladium is present in an amount of 0.5 % to 5% of the weight
of
the catalyst; (b) the combined amount of platinum and palladium present is at
least
0.75% to 5% of the weight of the catalyst; and (c) the combined amount of tin
and
rhenium present is at least 1.0% by weight of catalyst.
Embodiment #118 is a process of embodiment # 117, wherein (a) the
amounts and oxidation states of (i) the platinum group metals, (ii) the
rhenium and
tin promoters, as well as (iii) the ratio of platinum group metal to rhenium
and tin
promoters; and (iv) the acidity of the silicaceous support are controlled such
that at
least 80% of the acetic acid converted is converted to ethanol and less than
4% of
the acetic acid is converted to compounds other than compounds chosen from the
group consisting of ethanol, acetaldehyde, ethyl acetate, ethylene and
mixtures
thereof.
Embodiment #119 is a process of embodiment # 118, wherein the combined
weight of rhenium and tin present is from about 1 to 10% by weight of the
catalyst.
Embodiment #120 is a process of embodiment # 119, wherein the mole ratio
of platinum group metal to moles of rhenium and tin combined is from about 1:2
to
about 2:1.
Embodiment #121 is a process for hydrogenation of acetic acid comprising
passing a gaseous stream comprising hydrogen and acetic acid in the vapor
phase in
a mole ratio of hydrogen to acetic acid of at least about 4:1 at a temperature
of
between about 225 C and 300 C over a hydrogenation catalyst consisting
essentially
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of metallic components dispersed on an oxidic support, said hydrogenation
catalyst
having the composition:
PtvPdwRexSnyCapSigOr,
wherein the ratio of v:y is between 3:2 and 2:3; the ratio of w:x is between
1:3 and
1:5, p and q are selected such that p:q is from 1:20 to 1:200 with r being
selected to
satisfy valence requirements and v and w being selected such that
0.005 < (&2s - 1.7&w) 01055.
q
Embodiment #122 is a process of embodiment #121, wherein the process
conditions and values of v, w, x, y, p, q, and r are chosen such that at least
90% of
the acetic acid converted is converted to a compound chosen from the group
consisting of ethanol and ethyl acetate while less than 4% of the acetic acid
is
converted to alkanes.
Embodiment #123 is a process of embodiment # 122, wherein the process
conditions and values of v, w, x, y, p, q, and r are chosen such that at least
90% of
the acetic acid converted is converted to ethanol and less than 2% of the
acetic acid
is converted to alkanes.
Embodiment #124 is a process of embodiment # 122, wherein p is selected,
in view of any minor impurities present, to ensure that the surface of the
support is
essentially basic.
Embodiment #125 is a process for hydrogenation of acetic acid comprising
passing a gaseous stream comprising hydrogen and acetic acid in the vapor
phase in
a mole ratio of hydrogen to acetic acid of at least about 4:1 at a temperature
of
between about 225 C and 300 C over a hydrogenation catalyst consisting
essentially
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of metallic components dispersed on an oxidic support, said hydrogenation
catalyst
having the composition:
PtõPdwRexSnyAlzCapSigOr,
wherein v and y are between 3:2 and 2:3; w and x are between 1:3 and 1:5,
wherein
p and z and the relative locations of aluminum and calcium atoms present are
controlled such that Bronsted acid sites present upon the surface thereof are
counteracted by calcium silicate; p and q are selected such that p:q is from
1:20 to
1:200 with r being selected to satisfy valence requirements and v and w are
selected
such that
0.00S:5 tan2 17; <- 0.0 S.
q
Embodiment #126 is a process of embodiment #125, wherein the
hydrogenation catalyst has a surface area of at least about 100 m2/g and
wherein z
and p are controlled such that p ? z.
Embodiment #127 is a process of embodiment #125, wherein p is selected, in
view of any minor impurities present, to ensure that the surface of the
support is
essentially free of Bronsted acid sites.
Embodiment #128 is a process for hydrogenating alkanoic acids comprising
passing a gaseous stream comprising hydrogen and an alkanoic acid in the vapor
phase in a mole ratio of hydrogen to alkanoic acid of at least about 5:1 at a
temperature of between about 125 C and 350 C at a GHSV of at least about 1000
hr
i at a pressure of at least 2 atm over a hydrogenation catalyst, said
hydrogenation
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catalyst comprising (a) a platinum group metal chosen from the group
consisting of
platinum, palladium and mixtures thereof on a silicaceous support chosen from
the
group consisting of silica, calcium metasilicate and calcium metasilicate
promoted
silica; and (b) a metallic promoter chosen the group consisting of tin and
rhenium
and mixtures thereof, (c) the silicaceous support being optionally promoted
with a
second promoter chosen from the group consisting of: (i) a donor promoter
chosen
from the group consisting of alkali metals; alkaline earth elements and zinc
in an
amount of 1 to 5% by weight of the catalyst; (ii) a redox promoter chosen from
the
group consisting of : W03; Mo03i Fe203 and Cr203 in an amount of 1 to 50% by
weight of the catalyst; (iii)an acidic modifier chosen from the group
consisting of
Ti02; Zr02; Nb205; Ta205; and AI203 in an amount of 1 to 50% by weight of the
catalyst; and (iv) combinations of i, ii, and iii.
Embodiment #129 is a process of embodiment #128, wherein said alkanoic
acid is acetic acid, and wherein (a) platinum, if present, is present in an
amount of
0.5 % to 5% of the weight of the catalyst; (b) palladium, if present, is
present in an
amount of 0.5% to 5% of the weight of the catalyst; and (c) the metallic
promoter is
present in an amount of at least 0.5 to 10%.
Embodiment #130 is a process of embodiment #129, wherein the surface
area of the silicaceous support is at least about 150 m2/g.
Embodiment #131 is a process of embodiment # 130, wherein (a) platinum is
present in an amount of 1 % to 5% of the weight of the catalyst; (b)
palladium, if
present, is present in an amount of 0.25% to 5% of the weight of the catalyst;
and (c)
the combined amount of platinum and palladium present is at least 1.25% by
weight
of catalyst.
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Embodiment #132 is a process of embodiment #131, wherein tin is present in
an amount of 1 to 3% by weight of the catalyst.
Embodiment #133 is a process of embodiment #132, wherein the mole ratio
of tin to platinum group metal is from about 1:2 to about 2:1.
Embodiment #134 is a process of embodiment #132, wherein the molar ratio
of tin to platinum is from about 5:4 to about 4:5.
Embodiment #135 is a process of embodiment #132, wherein the silicaceous
support is essentially free of Bronsted acid sites not counteracted with
calcium
metasilicate and the surface area thereof is at least about 200 m2/g.
Embodiment #136 is a process of embodiment #132, wherein the weight
ratio of tin to platinum group metal is from about 2:3 to about 3:2.
Embodiment #137 is a process of embodiment # 128, wherein the mole ratio
of tin to platinum is from about 2:3 to about 3:2.
Embodiment #138 is a process for hydrogenating acetic acid comprising
passing a gaseous stream comprising hydrogen and acetic acid in the vapor
phase in
a mole ratio of hydrogen to acetic acid of at least about 4:1 at a temperature
of
between about 225 C and 300 C over a hydrogenation catalyst consisting
essentially
of : a catalytic metal chosen from the group consisting of : Fe, Co, Cu, Ni,
Ru, Rh, Pd,
Ir, Pt, Sn, Os, Ti, Zn, Cr, Mo and W as well as mixtures thereof in an amount
of from
about 0.1% to about 10% by weight; and an optional promoter, dispersed on a
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suitable support wherein the amounts and oxidation states of the catalytic
metal(s)
and the compositions of the support and optional promoter as well as reaction
conditions are controlled such that less than 4% of the acetic acid is
converted to
compounds other than compounds chosen from the group consisting of ethanol,
acetaldehyde, ethyl acetate, ethylene, diethyl ether and mixtures thereof; and
the
activity of the catalyst declines by less than 10% when exposed to a vaporous
mixture of acetic acid and hydrogen at a molar ratio of 10:1 at a pressure of
2 atm
and a temperature of 275 C and a GHSV of 2500 hr-1 for a period of 500 hours.
Embodiment #139 is a process of embodiment #138, wherein the support is
selected from: molecular sieve supports; modified silicaceous supports
modified
with a modifier selected from the group consisting of oxides and metasilicates
of
sodium, potassium, magnesium, calcium, scandium, yttrium and zinc as well as
precursors therefor and mixtures of any of the foregoing, and carbon supports.
Embodiment #140 is a process of embodiment # 139, wherein the catalytic
metals include platinum and tin and the selectivity to diethyl ether is over
80%.
Embodiment #141is a process of embodiment # 107, wherein support is a
zeolite support, and the selectivity to diethyl ether is over 90%.
Embodiment #142 is a process for production of ethanol and ethyl acetate by
reduction of acetic acid comprising passing a gaseous stream comprising
hydrogen
and acetic acid in the vapor phase in a mole ratio of hydrogen to acetic acid
of at
least about 4:1 at a temperature of between about 225 C and 300 C over a
hydrogenation catalyst comprising: (a) a platinum group metal chosen from the
group consisting of platinum, and mixtures of platinum and palladium on a
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silicaceous support chosen from the group consisting of silica, and silica
promoted
with up to about 7.5 calcium metasilicate, the amount of platinum group metal
present being at least about 2.0%, the amount of platinum present being at
least
about 1.5%; and (b) a metallic promoter chosen from the group consisting from
the
group consisting of rhenium and tin an amount of between about 1% and 2% by
weight of the catalyst, the mole ratio of platinum to metallic promoter being
between about 3:1 and 1:2; (c) the silicaceous support being optionally
promoted
with a second promoter chosen from the group consisting of (i) a donor
promoter
chosen from the group consisting of alkali metals; alkaline earth elements and
zinc in
an amount of 1 to 5% by weight of the catalyst; (ii) a redox promoter chosen
from
the group consisting of: W03; Mo03i Fe203 and Cr203 in an amount of 1 to 50%
by
weight of the catalyst; (iii) an acidic modifier chosen from the group
consisting of
Ti02; Zr02; Nb205; Ta205; and A1203 in an amount of 1 to 50% by weight of the
catalyst; and (iv) combinations of i, ii, and iii.
Embodiment #143 is a process of embodiment # 142, wherein the mole ratio
of metallic promoter to platinum group metal is from about 2:3 to about 3:2.
Embodiment #144 is a process of embodiment #142, wherein the mole ratio
of metallic promoter to platinum group metal is from about 5:4 to about 4:5.
Embodiment #145 is a process of embodiment #142, wherein the surface
area of the silicaceous support is at least about 200 m2/g and the amount of
calcium
metasilicate is sufficient to render the surface of the silicaceous support
essentially
free of Bronsted Acidity.
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Embodiment #146 is a process of embodiment #145, wherein the mole ratio
of metallic promoter to platinum group metal is from about 2:3 to about 3:2.
Embodiment #147 is a process of embodiment #146, wherein the surface
area of the silicaceous support is at least about 200 m2/g and the mole number
of
Bronsted Acid sites present on the surface thereof is no more than the mole
number
of Bronsted Acid sites present on the surface of Saint-Gobain NorPro SS61138
silica.
Embodiment #148 is a process of embodiment #142, wherein the surface
area of the silicaceous support is at least about 250 m2/g and the mole number
of
Bronsted Acid sites present on the surface thereof is no more than one half
the mole
number of Bronsted Acid sites present on the surface of Saint-Gobain NorPro
HSA
SS61138 silica.
Embodiment #149 is a process of embodiment #142, conducted at a
temperature of between about 250 C and 300 C, wherein (a) the hydrogenation
catalyst comprises palladium on a silicaceous support chosen from the group
consisting of silica, and silica promoted with up to about 7.5 calcium
metasilicate,
the amount of palladium present being at least about 1.5%; and (b) the
metallic
promoter is rhenium in an amount of between about 1% and 10% by weight of the
catalyst, the mole ratio of rhenium to palladium being between about 3:1 and
5:1.
Embodiment #150 is a process for reduction of acetic acid of embodiment
#142, wherein the hydrogenation catalyst consists essentially of platinum,
thereof
on a silicaceous support consisting essentially of silica promoted with from
about 3
up to about 7.5% calcium silicate, the amount of platinum present being at
least
about 1.0%, and a tin promoter in an amount of between about 1% and 5% by
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weight of the catalyst, the mole ratio of platinum to tin being between about
9:10
and 10:9.
Embodiment #151 is a process for reduction of acetic acid of embodiment
#142, wherein the amount of platinum group metal present is at least about
2.0%,
the amount of platinum present being at least about 1.5%, and a tin promoter
in an
amount of between about 1% and 5% by weight of the catalyst, the mole ratio of
platinum to tin being between about 9:10 and 10:9.
Embodiment #152 is a process of embodiment #151, conducted at a
temperature of between about 2502C and 300 C, wherein said hydrogenation
catalyst comprises: between 2.5 and 3.5 weight percent platinum, between 2
weight
% and 5 weight % tin dispersed on high surface area silica having a surface
area of at
least 200 m2 per gram, said high surface area silica being promoted with
between 4
and 7.5% calcium metasilicate.
Embodiment #153 is a process for production of a stream comprising ethanol
and at least about 40% ethyl acetate by reduction of acetic acid comprising
passing a
gaseous stream comprising hydrogen and acetic acid in the vapor phase in a
mole
ratio of hydrogen to acetic acid of at least about 4:1 at a temperature of
between
about 225 C and 300 C over a hydrogenation catalyst consisting essentially of
metallic components dispersed on an oxidic support, said hydrogenation
catalyst
having the composition:
PtõPdwRexSnYAl,TinCapSigOr,
wherein the ratio of v and y is between 3:2 and 2:3; the ratio of w and x is
between
1:3 and 1:5, wherein p and z and p, q and n are selected such that
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0.005<_ 2-p < = 011
q- 1.33n+1,772
with r being selected to satisfy valence requirements and v and w are selected
such
that
0.005 <_ (SZ5Y - g75w) < Ãx.05.
q+1.33n:+1..77z
Embodiment #154 is a process of embodiment #153, wherein the
hydrogenation catalyst has a surface area of at least about 100 m2/g.
Embodiment #155 is a process for hydrogenating acetic acid comprising
passing a gaseous stream comprising hydrogen and acetic acid in the vapor
phase in
a mole ratio of hydrogen to acetic acid of at least about 4:1 at a temperature
of
between about 225 C and 300 C over a hydrogenation catalyst consisting
essentially
of : a catalytic metal chosen from the group consisting of : Fe, Co, Cu, Ni,
Ru, Rh, Pd,
Ir, Pt, Sn, Os, Ti, Zn, Cr, Mo and W as well as mixtures thereof in an amount
of from
about 0.1% to about 10% by weight; and an optional promoter, dispersed on a
suitable support wherein the amounts and oxidation states of the catalytic
metal(s)
and the compositions of the support and optional promoter as well as reaction
conditions are controlled such that: i) more more than 50% of the acetic acid
converted is converted to ethyl acetate; (ii) less than 4% of the acetic acid
is
converted to compounds other than compounds chosen from the group consisting
of ethanol, acetaldehyde, ethyl acetate, ethylene, diethyl ether and mixtures
thereof; and the activity of the catalyst declines by less than 10% when
exposed to a
vaporous mixture of acetic acid and hydrogen at a molar ratio of 10:1 at a
pressure
of 2 atm and a temperature of 275 C and a GHSV of 2500 hr -1 for a period of
500
hours.
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Embodiment #156 is a particulate catalyst for hydrogenation of alkanoic
acids to the corresponding alkanol, comprising: (a) a platinum group metal
chosen
from the group consisting of platinum, palladium and mixtures thereof on a
silicaceous support chosen from the group consisting of silica, and silica
promoted
with from about 3.0 up to about 7.5 calcium metasilicate, the surface area of
the
silicaceous support being at least about 150 m2/g; and (b) a tin promoter in
an
amount of between about 1% and 3% by weight of the catalyst, the mole ratio of
platinum to tin being between about 4:3 and 3:4; (c) the composition and
structure
of the silicaceous support being chosen such that the surface thereof is
essentially
free of Bronsted acid sites not counteracted with calcium metasilicate.
Embodiment #157 is a hydrogenation catalyst of embodiment #156, wherein
the total weight of platinum group metals present is between 2 and 4%, the
amount
of platinum present is at least 2%, the weight ratio of platinum to tin being
between
4:5 and 5:4, and the amount of calcium silicate present is between 3 and 7.5%.
Embodiment #158 is a particulate hydrogenation catalyst consisting
essentially of: a silicaceous support having dispersed thereupon a platinum
group
metal chosen the group consisting of platinum, palladium, and mixtures thereof
with
a promoter chosen from the group consisting of tin, cobalt and rhenium, the
silicaceous support having a surface area of at least about 175 m2/g and being
chosen from the group consisting of silica, calcium metasilicate and calcium
metasilicate promoted silica having calcium metasilicate being disposed on the
surface thereof, the surface of the silicaceous support being essentially free
of
Bronsted acid sites due to alumina unbalanced by calcium.
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Embodiment #159 is a hydrogenation catalyst of embodiment #158, wherein
the total weight of platinum group metals present is between 0.5% and 2%, the
amount of palladium present is at least 0.5%, the promoter is rhenium, the
weight
ratio of rhenium to palladium being between 10:1 and 2:1, and the amount of
calcium meta-silicate is between 3 and 90%.
Embodiment #160 is a hydrogenation catalyst of embodiment #159, wherein
the total weight of platinum group metals present is between 0.5 and 2%, the
amount of platinum present is at least 0.5 %, the promoter is cobalt, the
weight ratio
of cobalt to platinum being between 20:1 and 3:1, and the amount of calcium
silicate is between 3 and 90%.
Embodiment #161 is a hydrogenation catalyst of embodiment #158, wherein
the total weight of platinum group metals present is between 0.5 and 2%, the
amount of palladium present is at least 0.5%, the promoter is cobalt, the
weight
ratio of cobalt to palladium being between 20:1 and 3:1, and the amount of
calcium
silicate is between 3 and 90%.
Embodiment #162 is a hydrogenation catalyst comprising: between 2.5 and
3.5 weight percent platinum, between 3 weight % and 5 weight % tin dispersed
on
high surface area pyrogenic silica having a surface area of at least 200 m2
per gram,
said high surface area silica being promoted with between 4 and 6% calcium
metasilicate, the molar ratio of platinum to tin being between 4:5 and 5:4.
Embodiment #163 is a hydrogenation catalyst comprising: between 0.5 and
2.5 weight percent palladium, between 2 weight % and 7 weight % rhenium, the
weight ratio of rhenium to palladium being at least 1.5:1.0, said rhenium and
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palladium being dispersed on a silicaceous support, said silicaceous support
comprising at least 80% calcium metasilicate.
Embodiment #164 is a particulate catalyst for hydrogenation of alkanoic
acids to the corresponding alkanol, comprising: (a) a platinum group metal
chosen
from the group consisting of platinum, palladium and mixtures thereof on a
silicaceous support chosen from the group consisting of modified stabilized
silicaceous support, said silicaceous support being modified and stabilized
with a
stabilizer-modifier chosen from the group consisting of (i) alkaline earth
oxides, (ii)
alkali metal oxides, (iii) alkaline earth metasilicates, (iv) alkali metal
metasilicates, (v)
zinc oxide , (vi) zinc metasilicate and (vii) precursors for any of (i)-(vi),
and mixtures
of any of (i)-(vii), the surface area of the modified stabilized silicaceous
support
being at least about 150 m2/g; and (b) a tin promoter in an amount of between
about 1% and 3% by weight of the catalyst, the mole ratio of platinum to tin
being
between about 4:3 and 3:4.
Embodiment #165 is a hydrogenation catalyst of embodiment #164, wherein
the total weight of platinum group metals present is between 2 and 4%, the
amount
of platinum present is at least 2%, the weight ratio of platinum to tin being
between
4:5 and 5:4, and the amount of stabilizer-modifier present is between 3 and
7.5%.
Embodiment #166 is a hydrogenation catalyst of embodiment #165, wherein
the support modifier is chosen from the group consisting of oxides and
metasilicates
of sodium, potassium, magnesium, calcium, and zinc as well as precursors
therefor
and mixtures of any of the foregoing.
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Embodiment #167 is a hydrogenation catalyst of embodiment #165, wherein
the support modifier is chosen from the group consisting of oxides and
metasilicates
of sodium, potassium, magnesium, calcium, and zinc as well as precursors
therefor
and mixtures of any of the foregoing.
Embodiment #168 is a hydrogenation catalyst of embodiment #165, wherein
the support modifier is chosen from the group consisting of oxides and
metasilicates
of magnesium, calcium, and zinc as well as precursors therefor and mixtures of
any
of the foregoing.
Embodiment #169 is a hydrogenation catalyst of embodiment #165, wherein
the support modifier is chosen from the group consisting of oxides and
metasilicates
of magnesium, calcium, and zinc as well as precursors therefor and mixtures of
any
of the foregoing.
Embodiment #170 is a hydrogenation catalyst of embodiment # 165, wherein
the support modifier is chosen from the group consisting of calcium
metasilicate,
precursors for calcium metasilicate and mixtures of calcium metasilicate and
precursors therefor.
Embodiment #171 is a hydrogenation catalyst of embodiment #164, wherein
the support modifier is chosen from the group consisting of oxides and
metasilicates
of sodium, potassium, magnesium, calcium, and zinc as well as precursors
therefor
and mixtures of any of the foregoing.
Embodiment #172 is a hydrogenation catalyst of embodiment #164, wherein
the support modifier is chosen from the group consisting of oxides and
metasilicates
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of sodium, potassium, magnesium, calcium, and zinc as well as precursors
therefor
and mixtures of any of the foregoing.
Embodiment #173 is a hydrogenation catalyst of embodiment #164, wherein
the support modifier is chosen from the group consisting of oxides and
metasilicates
of magnesium, calcium, and zinc as well as precursors therefor and mixtures of
any
of the foregoing.
Embodiment #174 is a hydrogenation catalyst of embodiment #164, wherein
the support modifier is chosen from the group consisting of oxides and
metasilicates
of magnesium, calcium, and zinc as well as precursors therefor and mixtures of
any
of the foregoing.
Embodiment #175 is a hydrogenation catalyst of embodiment #164, wherein
the support modifier is chosen from the group consisting of calcium
metasilicate,
precursors for calcium metasilicate and mixtures of calcium metasilicate and
precursors therefor.
Embodiment #176 is a particulate hydrogenation catalyst consisting
essentially of: a modified stabilized silicaceous support having dispersed
thereupon a
platinum group metal chosen the group consisting of platinum, palladium, and
mixtures thereof with a promoter chosen from the group consisting of tin,
cobalt
and rhenium, the silicaceous support comprising silica having a purity of at
least 95%
and having a surface area of at least about 175 m2/g modified and stabilized
with a
stabilizer-modifier chosen from the group consisting of (i) alkaline earth
oxides, (ii)
alkali metal oxides, (iii) alkaline earth metasilicates, (iv) alkali metal
metasilicates, (v)
zinc oxide , (vi) zinc metasilicate and (vii) precursors for any of (i)-(vi),
and mixtures
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of any of (i)-(vii),, the surface of the silicaceous support being essentially
free of
Bronsted acid sites due to alumina unbalanced by stabilizer-modifier.
Embodiment #177 is a hydrogenation catalyst of embodiment #176, wherein
the total weight of platinum group metals present is between 0.5% and 2%, the
amount of palladium present is at least 0.5%, the promoter is rhenium, the
weight
ratio of rhenium to palladium being between 10:1 and 2:1, and the amount of
support-modifier is between 3 and 90%.
Embodiment #178 is a hydrogenation catalyst of embodiment #177, wherein
the support modifier is chosen from the group consisting of oxides and
metasilicates
of sodium, potassium, magnesium, calcium, and zinc as well as precursors
therefor
and mixtures of any of the foregoing.
Embodiment #179 is a hydrogenation catalyst of embodiment #177, wherein
the support modifier is chosen from the group consisting of oxides and
metasilicates
of sodium, potassium, magnesium, calcium, and zinc as well as precursors
therefor
and mixtures of any of the foregoing.
Embodiment #180 is a hydrogenation catalyst of embodiment #177, wherein
the support modifier is chosen from the group consisting of oxides and
metasilicates
of magnesium, calcium, and zinc as well as precursors therefor and mixtures of
any
of the foregoing.
Embodiment #181 is a hydrogenation catalyst of embodiment #177, wherein
the support modifier is chosen from the group consisting of oxides and
metasilicates
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of magnesium, calcium, and zinc as well as precursors therefor and mixtures of
any
of the foregoing.
Embodiment #182 is a hydrogenation catalyst of embodiment #177, wherein
the support modifier is chosen from the group consisting of calcium
metasilicate,
precursors for calcium metasilicate and mixtures of calcium metasilicate and
precursors therefor.
Embodiment #183 is a hydrogenation catalyst of embodiment #176, wherein
the support modifier is chosen from the group consisting of oxides and
metasilicates
of sodium, potassium, magnesium, calcium, and zinc as well as precursors
therefor
and mixtures of any of the foregoing.
Embodiment #184 is a hydrogenation catalyst of embodiment #176, wherein
the support modifier is chosen from the group consisting of oxides and
metasilicates
of sodium, potassium, magnesium, calcium, and zinc as well as precursors
therefor
and mixtures of any of the foregoing.
Embodiment #185 is a hydrogenation catalyst of embodiment #176, wherein
the support modifier is chosen from the group consisting of oxides and
metasilicates
of magnesium, calcium, and zinc as well as precursors therefor and mixtures of
any
of the foregoing.
Embodiment #186 is a hydrogenation catalyst of embodiment #176, wherein
the support modifier is chosen from the group consisting of oxides and
metasilicates
of magnesium, calcium, and zinc as well as precursors therefor and mixtures of
any
of the foregoing.
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Embodiment #187 is a hydrogenation catalyst of embodiment #176, wherein
the support modifier is chosen from the group consisting of calcium
metasilicate,
precursors for calcium metasilicate and mixtures of calcium metasilicate and
precursors therefor.
Embodiment #188 is a hydrogenation catalyst of embodiment #176, wherein
the total weight of platinum group metals present is between 0.5 and 2%, the
amount of platinum present is at least 0.5 %, the promoter is cobalt, the
weight ratio
of cobalt to platinum being between 20:1 and 3:1, and the amount of support
modifier is between 3 and 90%.
Embodiment #189 is a hydrogenation catalyst of embodiment #188, wherein
the support modifier is chosen from the group consisting of oxides and
metasilicates
of sodium, potassium, magnesium, calcium, and zinc as well as precursors
therefor
and mixtures of any of the foregoing.
Embodiment #190 is a hydrogenation catalyst of embodiment #188, wherein
the support modifier is chosen from the group consisting of oxides and
metasilicates
of sodium, potassium, magnesium, calcium, and zinc as well as precursors
therefor
and mixtures of any of the foregoing.
Embodiment #191 is a hydrogenation catalyst of embodiment #188, wherein
the support modifier is chosen from the group consisting of oxides and
metasilicates
of magnesium, calcium, and zinc as well as precursors therefor and mixtures of
any
of the foregoing.
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Embodiment #192 is a hydrogenation catalyst of embodiment #188, wherein
the support modifier is chosen from the group consisting of oxides and
metasilicates
of magnesium, calcium, and zinc as well as precursors therefor and mixtures of
any
of the foregoing.
Embodiment #193 is a hydrogenation catalyst of embodiment #188, wherein
the support modifier is chosen from the group consisting of calcium
metasilicate,
precursors for calcium metasilicate and mixtures of calcium metasilicate and
precursors therefor.
Embodiment #194 is a hydrogenation catalyst of embodiment #176, wherein
the total weight of platinum group metals present is between 0.5 and 2%, the
amount of palladium present is at least 0.5%, the promoter is cobalt, the
weight
ratio of cobalt to palladium being between 20:1 and 3:1, and the amount of
support
modifier is between 3 and 90%.
Embodiment #195 is a hydrogenation catalyst of embodiment #194, wherein
the support modifier is chosen from the group consisting of oxides and
metasilicates
of sodium, potassium, magnesium, calcium, and zinc as well as precursors
therefor
and mixtures of any of the foregoing.
Embodiment #196 is a hydrogenation catalyst of embodiment #194, wherein
the support modifier is chosen from the group consisting of oxides and
metasilicates
of sodium, potassium, magnesium, calcium, and zinc as well as precursors
therefor
and mixtures of any of the foregoing.
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Embodiment #197 is a hydrogenation catalyst of embodiment #194, wherein
the support modifier is chosen from the group consisting of oxides and
metasilicates
of magnesium, calcium, and zinc as well as precursors therefor and mixtures of
any
of the foregoing.
Embodiment #198 is a hydrogenation catalyst of embodiment #194, wherein
the support modifier is chosen from the group consisting of oxides and
metasilicates
of magnesium, calcium, and zinc as well as precursors therefor and mixtures of
any
of the foregoing.
Embodiment #199 is a hydrogenation catalyst of embodiment #194, wherein
the support modifier is chosen from the group consisting of calcium
metasilicate,
precursors for calcium metasilicate and mixtures of calcium metasilicate and
precursors therefor.
Embodiment #200 is a hydrogenation catalyst comprising: between 2.5 and
3.5 weight percent platinum, between 3 weight % and 5 weight % tin dispersed
on
high surface area pyrogenic silica having a surface area of at least 200 m2
per gram,
said high surface area silica being promoted with between 4 and 6% calcium
metasilicate, the molar ratio of platinum to tin being between 4:5 and 5:4.
Embodiment #201 is a hydrogenation catalyst comprising: between 0.5 and
2.5 weight percent palladium, between 2 weight % and 7 weight % rhenium, the
weight ratio of rhenium to palladium being at least 1.5:1.0, said rhenium and
palladium being dispersed on a silicaceous support, said silicaceous support
comprising at least 80% calcium metasilicate.
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Embodiment #202 is a hydrogenation catalyst incorporating catalytic metals
chosen from the group consisting of: Fe, Co, Ni, Ru, Rh, Pd, Ir, Pt, Os, Ti,
Zn, Cr, Mo
and Win an amount of from about 0.1% to about 10% by weight on a
stabilized-modified oxidic support incorporating basic non-volatile
stabilizer-modifiers in the form of oxides and metasilicates of alkaline earth
metals,
alkali metals, zinc, scandium and yttrium precursors for the oxides and
metasilicates, as well as mixtures thereof in amounts sufficient to counteract
acidic
sites present on the surface thereof, impart resistance to shape change
(primarily
due to inter alia sintering, grain growth, gain boundary migration, migration
of
defects and dislocations, plastic deformation and/or other temperature induced
changes in microstructure) at temperatures encountered in hydrogenation of
acetic
acid or both.
Embodiment #203 is a hydrogenation catalyst of embodiment #202 wherein
the amount and location of basic modifier-stabilizer is sufficient to reduce
the
number of acid sites present per square meter on the surface of the oxidic
support
below the number of acid sites found per square meter on the surface of
pyrogenic
silica having a purity of at least about 99.7% by weight.
Embodiment #204 is a hydrogenation catalyst of embodiment #202 wherein
the amount and location of basic modifier-stabilizer is sufficient to reduce
the
number of acid sites present per square meter on the surface of the oxidic
support
below the number of acid sites found per square meter on the surface of Saint-
Gobain NorPro HSA SS 61138 having a purity of at least about 99.7% by weight.
Embodiment #205 is a hydrogenation catalyst of embodiment #202 wherein
the amount and location of basic modifier-stabilizer is sufficient to reduce
the
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number of acid sites present per square meter on the surface of the oxidic
support
below half the number of acid sites found per square meter on the surface of
pyrogenic silica having a purity of about 99.7% by weight.
Embodiment #206 is a hydrogenation catalyst of embodiment #202 wherein
the amount and location of basic modifier-stabilizer is sufficient to reduce
the
number of acid sites present per square meter on the surface of the oxidic
support
below half the number of acid sites found per square meter on the surface of
Saint-
Gobain NorPro HSA SS 61138 having a purity of at least about 99.7% by weight.
Embodiment #207 is a hydrogenation catalyst of embodiment #202 wherein
the amount and location of basic modifier-stabilizer is sufficient to reduce
the
number of acid sites present per square meter on the surface of the oxidic
support
below twenty five percent of the number of acid sites found per square meter
on
the surface of pyrogenic silica having a purity of about 99.7% by weight.
Embodiment #208 is a hydrogenation catalyst of embodiment #202 wherein
the amount and location of basic modifier-stabilizer is sufficient to reduce
the
number of acid sites present per square meter on the surface of the oxidic
support
below twenty five percent of the number of acid sites found per square meter
on
the surface of Saint-Gobain NorPro HSA SS 61138 having a purity of at least
about
99.7% by weight.
Embodiment #209 is a hydrogenation catalyst of embodiment #202 wherein
the amount and location of basic modifier-stabilizer is sufficient to reduce
the
number of acid sites present per square meter on the surface of the oxidic
support
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below ten percent of the number of acid sites found per square meter on the
surface of pyrogenic silica having a purity of about 99.7% by weight.
Embodiment #210 is a hydrogenation catalyst of embodiment #202 wherein
the amount and location of basic modifier-stabilizer is sufficient to reduce
the
number of acid sites present per square meter on the surface of the oxidic
support
below ten percent of the number of acid sites found per square meter on the
surface of Saint-Gobain NorPro HSA SS 61138 having a purity of at least about
99.7%
by weight.
In the foregoing descriptions of the various embodiments, those
embodiments which refer to another embodiment may be appropriately combined
with other embodiments as will be appreciated by one of skill in the art.
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