Note: Descriptions are shown in the official language in which they were submitted.
CATALYSTS H~VING ALKQXIDE-MODIFIED SUPPORTS
The present invention concerns supported
metal catalyst compositions.
It is known to employ metal alkoxides in the
preparation of solid catalysts. The reasons for employ-
ing the metal alkoxides vary considera~ly, as can beseen from the use of alkoxides in the preparation of
solid heterogeneous catalysts in the literature. For
example, U.S. Patent 3,873,489 discloses the prepara-
tion of metal catalysts for the purification of auto-
mobile exhaust gases. The cakalysts are prepared byimpregnating a precious metal such as platinum, pal-
ladium, rhodium, iridium, ruthenium or mixtures thereof
onto a monolithic honeycomb structure. The honeycomb
structure is composed of refractory compounds of low
surface area. The shemically inert and refractory
nature of this honeycomb is extremely important, as it
should not undergo any drastic transformations during
the extreme conditions encountered in typical auto-
mobile exhaust systems. However, impregnation of
precious metals onto such a support surface to obtain a
31,912D-F -1-~
1;25~
thermally stable catalyst having reasonably high metal
dispersion is practically impossible. This difficulty
is overcome in the teaching of the patent by employing
a metal alkoxide to "wash coat" the low surface area
honeycomb to obtain a honeycomb having higher surface
area. The higher surface area support is suitable for
catalyst preparation.
Similiarly, U.S. Patent 4,076,792 discloses
the use of metal alkoxides to prepare layered support
coatings on monolithic honeycombs to make catalysts
having both platinum and rhodium deposited on a wash
coated honeycomb. The wash coating method comprisès
the impregnation of the selected support structure with
the lower alkoxides of metals followed by the 1n situ
hydrolysis of the metal alkoxides to form an adherent
coating of hydrous metal oxides. The coated support
structure may then be fired to convert the hydrous
metal oxides to an oxide support coating of very high
- surface area and good porosity.
The use of metal alkoxides to supply alkali
metal ions in a nonaqueous form is described by R. Hombek,
J. Kijenski, and S. Malinowski (Warsaw, Poland) in a
paper presented at the Second International Symposium
on Scientific Bases for the Preparation of Heterogeneous
Catalysts, held at Louvain-la-Neu~e, Belgium, on Septem-
ber 4-7, 1978 (Proceedings published as Studies in
Surace Science and Catalysis, Vol. 3, by Elsevier
Scientific Publishing Company, Amsterdam/Oxford/New
York, 1979; see pages 595-603). Many industrial cata-
lysts, especially for dehydrogenation, and crackingprocesses, are modified by the controlled dosing of
31,912D-F -2-
125~
alkali metal ions to suppress the unwanted strong aci-
dity of the catalyst carrier or support. The new
alkali impregnation procedure, using alkali metal
alkoxides in alcoholic solutions, avoids the reaction
of water with dehydrated alumina support surfaces; this
is particularly important because the water causes
considerable changes in the properties of catalysts
prepared by the aqueous alkali-hydroxide addition
method.
Still another development r~ported by M.
Glinski and J. Kijenski (same Polish group as above) is
the method of impregnation with vanadyl tri-isobutoxide
to prepare vanadium-alumina and vanadium-silica catalyst
systems. This is described by the Polish au~hors in
their paper presented at the Third International
Symposium on Scientific Bases for the Preparation of
Heterogeneous Catalysis, Vol. 16, 1983; see page
553-561). As in the case of impregnation with
alkali-metal alkoxides, the application of vanadyl
alkoxide in a non-aqueous medium avoids the secondary
effects caused by the interaction of water with th~e
dehydrated alumina or silica surface. Following the
alkoxide impregnation, the resultant product was cal-
cined in a stream of dry air at 573 K for 3 hours to
obtain the respective vanadium-alumina or vanadium-
-silica catalysts, which can further be reduced if
necessary.
- The principle of bringing the catalytically
active material or materials in the form of an alkoxide
precursor, followed by hydrolysis or thermal decom-
position to obtain the final supported metal oxide or
metal catalyst, is also the basis of the invention of
31,912D-F -3-
-4~ ~5~
U.S. Patent 4,400,306. This method of catalyst pre-
paration comprises: impregnating a pre-formed catalyst
support with a solution of an alkoxide of at least one
metal selected from V, Mo, Sb, Nb, Ta, Zr, B and mix-
tures thereof; contacting the impregnated supportwith a solution of at least one additional catalyst
component to form the catalyst in situ; and drying or
calcining the thus formed catalyst. The preformed
catalyst support in such cases can be of different
types and shapes, e.g. non-porous or microporous
fluidizable powders, pellets or tablets, extrudates,
monoliths and similar forms. U.S. Patent 4,400,306
(at column 3, lines 22-31) reads "the use of metal
alkoxides in the impregnation step is advantageous
because the alkoxide reagent represents an extremely
pure source of the metal and metal oxide reagents,
unlike water-soluble salts such as the alkali metal or
sulfur-containing salts which carry possibly unwanted
counter-ions into the support material for incorpor-
ation into the catalyst. Upon heating or calcining,the alcohol adduct of the alkoxide is driven off or
oxidized to form a metal oxide species." This use of
the metal alkoxide as an extremely pure source of the
metal is also one of the motives for using it for
bringing a washcoat on monolith honeycombs, as des-
cribed in U.S. Patent 3,873,469. Still another embodi-
ment of the invention described in U.S. Patent 4,400,306
consists in `'choosing particular alkoxy derivatives of
reducible metal ions", so that an ln situ reduction of
the metal can be effected (column 3, lines 57-59).
The metal alkoxide impregantion step can also
be repeated to increase the amount of metal (or metal
oxide) deposited within the support. After the impreg-
31,912D-F -4-
~258~
nation of one metal alkoxide catalyst component, addi-
tional catalyst components can be added in the form of
metal alkoxide solutions or solutions of other catalyst
component compounds. Catalysts prepared in this way
are suitable for fixed-bed or fluid-bed catalytic
processes, particularly for oxidation processes like
the conversion of C4 hydrocarbons to maleic anhydride
(see U.S. Patent 4,455,434).
` To summarize, metal alkoxides have been used
in the prior art for the manufacture of solid catalysts
for the following distinct purposes and with the follow-
ing specific characteristics:
1. To wash-coat a monolithic honeycomb, to give
the inert refractory substrate higher surface
area and porosity for subsequent metal impre-
gnation (U.S. Patent 3,873,469; U.S. Patent
4,076,792).
2. To bring alkali metal ions in a water-free
system to catalysts to neutralize the unwanted
strong acidity of the catalysts. (Paper of
Hombek et al., 1978, supra. ).
3. To impregnate vanadium alkoxides on silica or
alumina to prepare supported vanadium cata-
lysts. The alkoxide is used as a water-free
medium to prevent side effects to the cata-
lyst support which would otherwise result
from using an a~ueous solution of a vanadium
salt. (Glinski and Kijenski, 1982, supra. ).
4. Use of the specific alkoxide of the cata-
lytically active metal.
31,912D-F -5-
--6--
125~
Motive: alkoxides are generally purer than
the corresponding metal salts, hence trace
impurities can be avoided if metal alkoxides
are used instead of metal salt solutions
(U.S. 4,400,306 and U.S. 4,4~5,~34).
Catalytic metals play an important role in
heterogeneous catalysis. The catalytic metals typi-
cally are employed on various support materials, as
only the surface of a metal particle can participate in
a catalytic process. Many people have proposed various
solutions to the long-standing problem of how to dis-
perse catalytic metals more efficiently on the surface
of a support material. An improved solution to this
problem is provided by the present invention.
In one aspect, the present invention concerns
an improved catalyst composition which comprises a
catalytic metal on an alkoxide-modified supportj which
support has a core support material having a surface
area of at least about 5 m2/g.
In another aspect, the invention is a process
for increasing the catalytic activity of a catalytic
metal ! which comprises supporting the catalytic metal
on a support prepare~ by contacting a metal alkoxide
with a core support material, then calcining the mix-
ture of the metal alkoxide and the core support mater-
` ial, thereby leaving a coating on the core support, the
coating havin~ the metal oxide derived from the cal-
cination of the metal alkoxide.
31,912D-F -6-
-7- ~25~9
Surprisingly, the supported catalyst com-
position of the present invention exhibits increased
catalytic activity compared to supports not treated by
the process of this invention. Thus, the catalyst com-
position of the present invention is useful in many
catalytic processes in which enhanced activity of a
supported metal catalyst is desirable. The catalyst
composition of the present invention is suitable for
use in:
(a) the disproportion of alkenes;
(b) a vapor phase process for the prepara-
tion of -
(1) ~-substituted acrylate esters; or
- (2) methylmethacrylate;
(c) a process for selectivel~ hydrogenating
a hydrocarbon feed composition having at least one
alkene and at least one alkyne wherein the alkyne is
hydrogenated without substantially hydrogenating the
alkene; or
(d) a process for preparing increased yields
of methane by reacting carbon monoxide and hydrogen.
The catalyst composition of the present
invention has two re~uired components: a catalytic
m~tal; and-an alkoxide-modified support. For the pur-
poses of the present invention, the term "alkoxide-
modified support" means a material prepared by deposit-
ing a thin layer of a metal alkoxide on a core support
material and then converting the metal alkoxide to the
oxide of said metal. Additonally, the term "catalytic
metal" refers to any metal-containing compound, complex
or other èntity which acts as a catalyst.
31,912D-F -7-
-8- ~25~
The alkoxide-modified support comprises a
core support material having on its outer surface a
thin layer of a metal oxide produced from a precursor
metal alkoxide. The core support material can be any
material, such as a refractory oxide, which will not
decompose or melt when subjected to calcination.
Examples of typical core support materials include
alumina, zirconia, boria, thoria, magnesia, titania,
tantala, chromia, silica, kieselguhr and mixtures of
these materials. The aluminas and silicas are pre-
ferred in view of their low cost. The core support
material typically has a surface area which is greater
than about 5 m2/g, preferably about 10 to S00 m2/g,
more preferably 20 to 200 m2/g, and most preferably
over 100 m2/g prior to the deposition of the metal
alkoxide salt precursor. These surface areas are as
measured by the Brunauer-Emmett-Teller (BET) method.
The BET method is described by R. B. Anderson, Experi-
mental Methods in Catalytic Research, pp. 48-66, Academic
Press, 1968.
The precursor metal alkoxide salt can be the
alkoxide of almost any metal so long as said metal
alkoxide will thermally decompose to form a metal
oxide. For example, the metal of the metal alkoxide
can be a metal of Group IIA. Examples of preferred
metals for use in the precursor metal alkoxide include
the metals of Groups IIIA, IVA, IVB and VB of the
Perodic Table of the elements. Examples of typical
precursor metal alkoxides include Al[OCH~CH2CH3][CH3~]3,
Ti[OCH(CH3~2]4, Ta[OCH(CH3)2~s, Si(OC2H5~4, Nb2(C2~I5~10'
Ta (OC H5~10' Si(C4Hg~4, Al(oc5Hll~3l
Typically, the alkoxide moiety has from 1 to about
10 carbon atoms, preferably from about 2 to about 4
carbon atoms. Mixtures of metal alkoxidrs can be
31,912D-F -8-
9 125~
employed. Typi cally, the metal of the metal alkoxide
is not a catalyst for the reaction in which the cata-
lyst composition will be employed.
The alkoxide-modified support is prepared by
technigues known in the art, e.g., incipient wetness
impregnation techni~ues. Metal oxide precursors are
deposited on the selected core support material fol-
lowed by conversion into the oxide form b~ calcination.
The alkoxide-modified support is prepared by impregna-
ting the desired core support material with a solutionof an alkoxide precursor of the desired metal oxide.
The solution used in impregnating the core support
material preferably is organic , the only requirement
being that an adequate amount of precursor compound for
the selected metal oxide is soluble in the solvent used
in p~eparing the impregnating solution. Hydrocarbon or
alcohol solutions, preferably hexane solutions, are
normally used for convenience. When using the impre-
gnation technique the metal alkoxide impregnating
solution is contacted with the core support material
for a time sufficient to deposit the metal alkoxide
precursor material onto the carrier either by selective
adsorption or, alternatively, the excess solvent may be
evaporated during drying leaving behind the preGursor
metal alkoxide. Advantageously, the incipient wetness
technique may be used whereby just enough of a precur-
sor metal àlkoxide solution is added to dampen and fill
the pores of the powder of the above-recited core
support material.
The composite thus prepared by any of the
above-recited techniques, or by any other technique
31,912D-F -9-
-10- ~25~ 9
known in the art, is dried, typically at a temperature
of from 50 to 300~C, to remove the excess solvent.
The solvent can be removed ln vacuo. The dried metal
alkoxide can then be converted into the oxide form by
exposure at temperatures typically of from 150 to
800C, preferably 300 to 700C in an atmosphere such as
2' air, He, Ar or combinations thereof. This exposure
is for a time sufficient to convert essentially all of
the metal alkoxide precursor into metal oxide. The
calcination is useful to decompose the metal precursor
to the oxide form.
The catalytic metal can be any metal or metal
compound having catalytic activity. Typical catalytic
'metals include the transition metals. Examples of pre-
ferred catalytic metals include the metals of Group VIIIof the Periodic Table of the elements, i.e~, iron,
ruthenium, osmium, cobalt, rhodium, iridium, nickel,
palladium and platinum, and the metals of Group VIIB,
e.g. rhenium. The catalytic metal is deposited on the
alkoxide-modified support via methods known in the art
such~as, for example, impregnation of the alkoxide-
modified support with a salt of the catalytic metal.
The salt of the catalytic metal is converted to the
metal by exposing the salt to a reducing atmosphere via
methods known in the art. It is preferred to reduce
the salt of the catalytic metal in situ, i.e., while
the salt is in the reaction vessel.
The precursor metal alkoxide is employed in
an amount sufficient to result in a finished alkoxide-
modified support which, after calcination, can beemployed with a catalytic metal to form a composite
catalyst composition having improved activity, which
31,912D-F -10-
125~
may be evidenced, e.g., by increased conversion or
lifetime. Typically, the support has up to about a
molecular monolayer of the metal oxide, formed from the
metal alkoxide, covering the entire outer surface of
the core support material. If desired, more than a
molecular monolayer of the metal oxide from the metal
alkoxide can be employed. Typically, the catalytic
metal is employed in a catalytic amount. Pre~erably,
the finished catalyst of the present invention will
have a composition as follows: from about 0.01 to
a~out 20 weight percent catalytic metal; from about 0.1
to about 50 weight percent of metal oxide from alkoxide
precursor; and the remainder being core support material-.
More preferably, the finished catalyst of the present
invention will have a composition as follows: from
about 0.02 to about 10 weight percent catalytic metal;
from about 1 to about 5 weight percent metal oxide from
alkoxide precursor; and the remainder being core support
material.
A. Methanation
The catalyst composition of the present
invention is useful in many applications in which
enhanced activity of a supported catalytic metal is
desirable. The production of methane from C0 and H2 is
an example of a preferred use of the catalyst composi-
tion of the present invention. The art contains many
examples of metals known to be useful in reac-ting
carbon monoxide with hydrogen to produce a variety of
compounds, including hydrocarbons and oxygenated com-
pounds. These metals include, among others, Mo, W, Rh,Ru, Re, Pd, Ni, Co, and Fe. In what has come to be
called the Fischer-Tropsch ~ynthesis, carbon monoxide
and hydrogen are reacted over a me-tal catalyst to
produce saturated an~ unsaturated hydrocarbons and
oxygenated compounds containing from 1 to as many as
31,91~D-F -11-
~25~
-12-
1000 carbon atoms. The hydrocarbons can be aliphatic,
alicyclic, or aromatic. Commercial utilization of this
synthes-s prior to 1950 was accomplished largely in
Germany and is summarized in Storch, Columbic, and
Anderson: The Fischer-Tropsch and Related Synthesis,
John Wiley and Sons, New York, 1951.
The major disadvantage in the prior art pro-
cesses and catalysts is that most of th~m are not
capable of selectively producing methane. Surpris-
ingly, at least one catalyst of the present inventionmay be used to produce methane ~electively by con-
tacting carbon monoxide and hydrogen in the presence of
said catalyst under reaction conditions.
The carbon monoxide required for the process
can be obtained from any carbon source, such as from
the degradation of coal. The molar ratio of hydrogen
to carbon monoxide ranges generally from at least about
0.1 to about 10, and preferably is from about 1 to
about 3.
Process reaction conditions can vary over a
rather wide range. The pressure can vary from at least
about 1 psig up to about 1500 psig (108 to 10,436 kPa).
Atmospheric pressure is preferred for convenience.
The reaction temperature typically ranges from at least
about 200C to about 600C and preferably is from about
200C to about 300C. Ruthenium is the preferred
catalytic metal for use in the production of methane
via the process of the present invention.
31,912D-F -12-
-13- l~S~
B. Olefin Metathesis
The disproportionation, or metathesis, of
olefins is another example of an advantageous use of
the supported catalyst composition of the present
invention. In a typical olefin metathesis process an
olefin of at least 3 carbon atoms is converted into a
mixture of new products comprising olefins of both
higher and lower molecular weight compared to the
olefin fed. Olefin metathesis was discovered in the
early 1960s. The metathesis xeaction is well known, as
is evidenced by the numerous publications which are
reviewed in Catalysis, Yol. 4, pp. 101-130, 1980. A
review of the prior art indicates that it would be
desirable to have a catalyst having a longer lifetime
or which would require fewer regenerations per unit
time. Surprisingly, at least one catalyst of the
- present invention may be employed in the metathesis of
olefins for increased lengths of time while maintaining
an acceptable rate of olefin conversion.
The olefin metathesis process of the present
invention involves contacting at least one alkene with
a catalyst o~ the present invention under reaction con-
ditions such that there is formed at least one product
of olefin metathesis, i.e., at least one alkene having
a molecular weight which is different than the molecular
weight of the alkene fed to the reactor.
Alkenes which are subject to disproportion-
ation according to the process of the present invention
- include acyclic alkenes having at least 3 carbon atoms,
and their aryl derivatives and mixtures thereQf.
Preferred are alkenes having from 3 to about 30 carbon
atoms and mixtures thereof. More preferred are mono-l-
31,912D-F -13-
125~
-14-
and 2-alkenes, such as, for example, propene, butene-l,
and mixtures of these alkenes, such as, for example, a
mixture of butene-l and butene-2. Most preferably, the
process of the present invention is applied to butene-1
or a mixture of butene-l and butene-2. Optionally, an
inert material may be included in the alkene fed to the
reactor. Examples of inert materials include inert
gases, such as helium, and saturated hydrocarbons, such
as hexane, cyclohexane, and the like.
Catalysts suitable or use in the olefin meta-
thesis process of the present invention are those
materials which catalyze the olefin metathesis reaction;
typically, the catalyst is a conventional catalytic
material on an alkoxide-modified support. Examples of
said conventional catalysts include materials which
contain catalytic metals such as rhenium, molybdenum or
tungsten, and which optionally include a promoter, such
as tetramethyltin or tetrabutyltin. Preferred catalysts
comprise rhenium or a rhenium compound or complex.
Rhenium oxides are preferred for use in the catalysts of
the process of the present invention. It is especially
preferred to employ from about 1 to about 8 w~ight
percent catalytic metal in the composite catalyst for
olefin metathesis.
The com~osite olefin metathesis catalyst is
prepared by suitable known methods of applying a
catalytic material to a support, such as impregnation or
coprecipitation, with impregnation being preferred.
Catalytic metal oxides or compounds convertible to
catalytic metal oxides by calcination preferably are
employed in the catalyst preparation.
31,912D-F -14-
.
-15- ~25~
After the catalytic metal oxide, or compound
which may be converted to a catalytic metal oxide by
calcination, is associated with the alkoxide-modified
support, the composite is subjected to a calcination or
activation step before being utilized in the 012fin
conversion process. The activation technique comprises
heating at elevated temperatures in the presence of a
suitable flowing gas. Air is a preferred activation gas,
although other gases, for example, inert gases such as
nitrogPn or the noble gases, may be used, provided that
at least part of the catalytic metal present in the
catalyst composition is in the oxide form at the com-
pletion of the activation. The catalysts are subjected
to a temperature which is generally in the range of 300C
15 to 700C for about 0.5 to 20 hours or longer. Generally,
longer activation periods are used with lower temper-
- atures, and shorter activation periods are used with
higher temperatures. In some instances, the catalyst may
be heated serially in more than one gas.
The activated catalyst may be used, without
regeneration, for runs of up to several days or more, and
may be regenerated. The regeneration is accomplished by
suitable methods for regenerating oxide catalysts and may
comprise the same steps used in the activation procedure.
The reactor employed in the olefin metathesis
process o~ the present invention can be of any known
design. The reactor is operated so as to dispro-
portionate the alkenes in the feed stream. Accordingly,
the reactor may be operated under any conditions, at
which disproportionation is achieved. Typically, the
operating temperature in the reactor ranges from about
-50C to about 300C, and preferably will be from about
31,912D-F -15-
-16- ~2s~
0C to about 150C. The pressure in the reactor
typically will be from about zero to about 1000 psig
(100 to 7000 kPa) and preferably will be from about 50
to about 3Q0 psig (400 to 2200 kPa). Higher or lower
temperatures and pressures may be employed; however,
beyond the lower end of the range the reaction will
proceed slowly, if at all, and beyond the higher end of
the range, undesirable side reactions and coke forma-
tion may occur. Additionally, it will probably be more
expensive to operate outside the ranges given.
For the purposes of the metathesis process of
the present invention, the term conversion refers to
the elimination of the alkenes in the feed stream from -
the reaction mixture. For example, in the practice of
this invention, butene-l may be converted to ethylene
and hexene-3 under the proper conditions. For the
purposes of the present in~ention, the term selectivity
refers to the percentage of the converted feed which
goes to the desired major products.
The concept of simultaneous high selectivity
and high conversion may be expressed conveniently in
terms of yield. For the purposes of the present inven-
tion, the term "yield" refers to the numerical product
of conversion and selectivity. For example, a process
according to the present invention operating at a
conversion of 0.75 and a selectivity of 0.90 would have
a yield of 0.675, which is the numerical product of
0.75 and 0.90.
C. Carbonylation
~0 The carbonylation of haloalkenes is a further
example of an advantageous use of the supported catalyst
31,912D-F -16-
125~
-17-
composition of the present invention. The carbonyla-
tion reaction of the present invention is a process for
the preparation of ~-substituted acrylate esters~which
involves contacting a haloalkene with carbon monoxide
and an alcohol or an ether in the presence of a catalyst
of the present invention under reaction conditions such
that an ~-substituted acrylate ester is prepared.
The preparation of acrylate esters by con-
tacting haloalkenes, carbon monoxide, and an alcohol or
ester in the presence of a heterogeneous catalyst is
generally known. For example, see U.S. Patent
4,480,121 for a description of reactants and reaction
conditions employed in the preparation of acrylate
esters.
The haloalkenes useful in this invention
include any halogenated olefinic compound wherein the
halogen is substituted on an olefinic carbon atom,
wherein such carbon atom is further substituted with a
Cl 10 alkyl, C3 10 cycloalkyl~ C6_l0 aryl~ C7_10 alkaryl~
C7 10 aralkyl, cyano, or trihalomethyl group. The
haloalkene preferably is vaporizable under the reaction
conditions. Olefinic carbon atoms means herein a
carbon a-tom which is doubly bonded to another carbon
atom. Haloalkenes useful in this i~vention include
those which correspond to the formula
(Rl)2-c=c-R2
31,912D-F -17-
-13- 125~3~r~
wherein
~ 7-10 aryl, Cl_10 alkyl~ C3 10 cyclo-
alkyl, C7_10 alkaryl, C7_10 aralkyl, substituted
Cl 10 alkyl, substituted C6 10 aryl, substituted
C3 10 cycloalkyl, substituted C7 10 alkaryl or sub-
stituted C7 10 aralkyl, wherein the substituent is a
nitro, cyano, carbonyloxyhydrocarbyl, formyl, amino,
hydroxyl, amido or halo group;
C1_l0 alkyl, C3_10 cycloalkyl, C6 10
aryl, C7 10 alkaryl, C7_10 aralkyl, cyano or tri-
halomethyl; and
X is halogen.
Examples of preferred haloalkenes useful in
this invention include 2-chloropropene, 2-bromopropene,
2-chlorobutene, 2-bromobutene, 2-chloropentene, 3-chlo-
ropentene, 2-bromopentene, 3-bromopentene, 2-chlorohex-
ene, 3-chlorohexene, 2-bromohexene, 3-bromohexene, and
the like. More preferred haloalkenes include 2-chloro-
propene~ 2-chlorobutene, 2-chloropentene, and 2-chloro-
hexene. A most preferred haloalkene is 2-chloropropene.
.
Alcohols useful in this invention include those
which are vaporizable under reaction conditions and which
will react under the reaction conditions to esterify the
carbonylated haloalkene so as to prepare an ~-substituted
acrylate ester. Preferred alcohols include those which
correspond to the formula, R30H, wherein R3 is C1 10
alkyl, C3 lO cYClalkYl' C6-10 aryl, C7_10 Y
C7 10 aralkyl. Examples of alcohols useful in ~his
invention include methanol, ethanol, propanol, butanol,
hexanol, heptanol, octanol, nonanol, decanol, cyclopro-
panol, cyclobutanol, cyclopentanol, cyclohexanol, cyclo-
heptanol, cyclooctanol, phenol, be~zyl alcohol, and the
31,91~D-F -18-
~ Z5~r6~9
--19--
like. Preferred alcohols are methanol, ethanol,
propanol, butanol, and pentanol. Methanol is the most
preferred alcohol.
Ethers useful in this invention include those
which are va~orizable under reaction conditions and which
will react under the reaction conditions to esterify the
carbonylated haloalkene so as to prepare an ~-substitute~d
acrylate ester. Among classes o ethers useful in this
invention are the dihydrocarbyl ethers and cyclic ethers.
Preferred dihydrocarbyl ethers include those which
correspond to the formula R3-o-R3 wherein R3 is as
defined hereinbefore. Examples of dihydrocarbyl ethers
useful in this in~ention are dimethyl ether, diethyl
ether, dipropyl ether, dibutyl ether, dipentyl ether,
diphenyl ether, dibenzyl ether and the like. Preferred
ethers are dimethyl ether, diethyl ether and dipropyl
ether; with dimethyl ether being most preferred.
Unsymmetrical dihydrocarbyl ethers such as methyl ethy~
ether, can be used in this invention although the
symmetrical ethers are preferred. Preferable cyclic
ethers useful in this process include those which
correspond to the formula
R4 R4
or 0
~ 0 ~ ~ R4 J
wherein R4 is a hydrocarbylene radical. The dihydrocar-
byl ethers are preferred over the cyclic e~hers. Cyclic
ethers useful in this invention include dioxane, tetra-
hydrofuran and the like.
31,912D-F -19-
-20- ~zS~r~
The product o~ the carbonylation process of -the
present invention is an acrylate ester. Preferred ~-sub-
stituted acrylate esters include those which correspond
to the formula
0
(Rl)2-C=C-CoR3
~2
or
(Rl )2-C=C-CoR4-H
R2
wherein R1, R2, R3 and R4 are as hereinbefore defined.
Examples of acrylate esters prepared by this
process include methyl methacrylate, methyl 2-methyl-2-
-butenoate, methyl 2-methyl-2-pentenoate, ethyl methacry-
late, ethyl 2-methyl-2-butenoate, ethyl 2 methyl-2-pente-
noate, propyl methacrylate, propyl 2-methyl-2-butenoate,
propyl 2-methyl-2-pentenoate, butyl methacrylate, butyl
2-methyl-2-butenoate, butyl 2-methyl-2-butenoate, pentyl
methacrylate, pentyl 2-methyl-2-butenoate, and pentyl
2-methyl-2-pentenoate. Preferred acrylate esters include
methyl methacrylate, ethyl methacrylate, propyl
methacrylate, butyl methacrylate, and pentyl meth-
acrylate, more preferred acrylate esters include methyl
methacrylate, ethyl methacrylate, and propyl meth-
acrylate, with methyl methacrylate bein~ most preferred.
31,912D-F -20-
-21~ 4~
A co-product of this invention is a hydrocarbyl
halide. This halide is the reaction product of an
alcohol or an ether and the halogen abstracted from the
haloalkene during the carbonylation and esterification
process of this invention. The excess alcohol or ether
functions as the halogen acceptor for this reaction
thereby reducing the concentration of hydrogen halide in
the reactor and preventing corrosion. Furthermore, the
preparation of an alkyl halide allows the recovery of the
halogen in a valuable form. Hydrocarbyl halides prepared
in this invention include those which correspond to the
formula, R3-X or R4H-X, wherein R3 and R4 are as
hereinbefore defined.
Tertiary amines may be used as hydrogen halide
acceptors. When tertiary amines are used as acid
acceptors, by-products of the process are the quaternary
ammonium halides. The use of excess alcohols or ethers
to serve as the halogen acceptor is preferred over the
use of the tertiary amines in this invention.
Examples of haloalkanes prepared by this pro-
cess include chloromethane, chloroethane, chloropropane,
chlorobutane, chloropentane, chlorohexane, chloroheptane,
chloroocatne, chlorononane, chlorodecane, chlorocyclopro-
pane, chlorocyclobutane, chloxocyclopentane, chlorocyclo-
hexane, chlorobenzene, chloromethylbenzene, bromomethane,
bromoethane, bromopropane, bromobutane, bromopentane,
bromohexane, bromoheptane, bromooctane, bromononane,
bromodecane, bromocyclopropane, bromocyclobutane, bromo-
cyclopentane, bromocyclohexane, bromobenzene, and bromo-
methylbenzene. Examples o~ more pre~erred haloalkanesinclude chloromethane, chloroethane, chloropropane,
chlorobutane, chloropentane, chlorohexane, chloroheptane,
31,912D-F -21-
-22-
~5~..49
chlorooctane, chlorononane, chlorodecane, chlorocyclopro-
pane, chlorocyclobutane, chlorocyclopentane, chlorocyclo-
hexane, chlorobenzene, and chloromethylbenzene. Even
more preferred haloalkanes include chloromethane, chloro-
ethane, chloropropane, chlorobutane and chloropentane,with chloromethane being most preferred.
In the process of this invention, the halo-
alkene starting material is carbonylated by the insertion
of carbon monoxide onto an olefinic carbon atom, and the
carbon atom on the carbon monoxide moiety inserted is
transesterified with the alcohol or ether. This process
can be best illustrated by the following e~uations,
X R2 o
..
(Rl)2-C-C-R2 + C0 + 2R30H , (R1~2_C=C - CoR3 + R3-X + ~2
and
X R2 o
(Rl)2-C=C-R2 + C0 + R30R3 ~ (Rl)2-C=C - CoR3 + R3-X
. .
wherein Rl, R2, R3, and X are as hereinbefore defined.
In the hereinbefore defined formulas, Rl is
preferably hydrogen or Cl 10 alkyl. Rl is more prefer-
ably hydrogen or Cl 5 alkyl and most preferably hydrogen.
R is preferably Cl 10 alkyl. R2 is more preferably C1 5
alkyl and most pre~erably methyl. R3 is preferably Cl 10
alkyl, R3 is more preferably Cl 5 alkyl and most pre-
- ferably methyl. R4 is preferably C2 10 alkylene and more
preferably C2 5 alkylene. X is preferably chlorine or
bromine and most preferably chlorine.
- 31,912D-F -22-
~L25~ 9
-23-
For the purposes of the present invention, the
term "hydrocarbyl" means an organic radical containing
carbon and hydrogen atoms. The term hydrocarbyl includes
the following organic radicals: alkyl, alkenyl, alkynyl,
cycloalkyl, cycloalkenyl, aryl, aliphatic and cyclo-
aliphatic aralkyl and alkaryl. Aliphatic refers herein
to straight- and branched-, and saturated and
unsaturated, hydrocarbon chains, that is, alkyl, alkenyl
or alkynyl. Cycloaliphatic refexs herein to saturated
and unsaturated cyclic hydrocarbons, that is, cyclo-
alkenyl and cycloalkyl. The term aryl refers herein to
biaryl, biphenylyl, phenyl, naphthyl, phenanthranyl,
anthranyl and two aryl groups bridged by an alkylene
group. Alkaryl refers herein to an alkyl-, alkenyl- or
alkynyl-substituted aryl substituent wherein aryl is as
defined hereinbefore. Aralkyl means herein an alkyl,
alkenyl or alkynyl group substituted with an aryl group,
wherein aryl is as defined hereinbefore. Cl 20 alkyl
includes straight- and branched-chain methyl, ethyl,
propyl, buty~, pentyl, hexyl, heptyl, octyl, nonyl,
decyl, und~cyl, dodecyl, tridecyl, tetradecyl, pent-
adecyl, hexadecyl, heptadecyl, octadecyl, nonadecyl and
eicosyl groups. Cl 5 alkyl includes methyl, ethyl,
propyl, butyl and pentyl.
Cycloalkyl refers to alkyl groups containing
one, two, three or more cyclic rings. Cycloalkenyl
refers to mono-, di- and polycyclic groups containing one
or more double bonds. Cycloalkenyl also refers to cyclo-
alkenyl groups wherein two or more double bonds are
present.
_ The catalytic metals useful in the carbonyl-
ation process are palladium, platinum, rhodium,
31,~12D-F -23-
-24- 1~5~ 4~
ruthenium, nickel and mixtures thereof. Preferred
catalytic metals are palladium and nickel, with palladium
being most preferred.
The carbonylation catalyst comprises an alkoxide-
-modified support with a sufficient amount of one of the
hereinbefore described metals loaded thereon to give the
- desired catalyst productivity for the claimed process.
The catalyst preferably comprises an alkoxide-modified
support with between about 0.1 and 10 percent by weight
of the hereinbefore described metal, more preferably
between about 1 and 10 percent by weight, and most pre-
ferably between about 3 and 7 percent.
The carbonylation catalysts preferably are
prepared by incipient wetness techniques, which are
- 15 well-known in the art. In particular, a salt of the
- metals described hereinbefore is dissolved in water or an
aromatic hydrocarbon and thereafter contacted with the
particular support. Exampies of salts which can be used
include metal acetates, metal halides, metal nitrates,
and the like.
A particularly preferred catalyst comprises
palladium deposited onto an alkoxide-modifed support
wherein the core support is ~-alumina and the metal of
the metal alkoxide is alumina. Preferred supports have a
surface area from about 10 m2/g to about 350 m2/g and
more preferably from about 100 m2/g to about 300 m2/g.
In a preferred carbonylation catalyst pre-
paration procedure, a previously prepared alkoxide-
modified support and an aqueous hydrochloric acid
solution of a palladium salt ha~ing a pH of 3.0 or less
31,912D-F -24-
-25-
are contacted at elevated temperatures. Preferably, the
support is heated to a temperature from about 75C to
about 150C and the aqueous hydrochloric acid solution is
heated to a temperature of from about 50C to about 95C
at the time th~ support and solution are contacted. Onlv
sufficient solution so as to result in incipient wetness
of the substrate is employed. Accordingly, the volume
and metal concentration of the aqueous solution are
adjusted to provide sufficient metal loadings and
sufficient volume of liquid to completely wet the
support, but not provide more liquid than can be absorbed
by the support. Preferably, the agueous solution has a
pH of 2.0 or less.
After impregnation with the palladium solution,
the catalyst preferably is dried in flowing air at
ele~ated temperatures up to about 300C for several
hours. Reduction may then occur employing hydrogPn under
the temperatures and conditions described hereinafter.
The carbonylation catalyst preferably is
activated by passing hydrogen gas over the impregnated
catalystic support at a temperature of between about
150C and 350C, for a period of time to reduce a sig-
nificant amount of the metal salt impregnated on the
support. Preferably, the hydrogen gas is passed over the
support at a temperature of between about 225C and
300C, with between about 240C and 280C being most
preferred. It is preferable to flow hydrogen gas over
the catalyst for a time period of between about 1 and 10
hours.
It is believed that during the activation
procedure the metal is reduced to the zero valence state,
which is believed to be the catalytic species.
31,912D F -25-
-26-
~SB~
In general, the support is impregnated with a
sufficient amount of metal so as to create a carbony-
lation catalyst which is active under the reaction
conditions. The amount of active metal on the carrier
can be between about 0.01 and 99 percent by weight of the
support. Preferably, the catalyst contains between about
0.1 and 10 percent by weight of active metal. Even more
preferably, the catalyst contains between about 1 and 10
percent by weight of the active metal, with between about
3 and 7 percent by weight of the active metal on the
catalyst being most preferred.
It has been discovered that the presence of an
alcohol or ether in the reactants results in significant
increases in the productivity of the catalyst for the
15 ~-substituted acrylate ester. The mole ratio of the
alcohol to the haloalkene in the feed composition has a
significant effect on the productivities, conversions and
selectivities. The productivities, conversions and
selectivities are enhanced as the equivalent ratio of
alcohol or ether to haloalkene increases from 1:1 to 2:1,
at 2:1 the productivities, conversions and selectivities
are optimized. The ratio of alcohol or ether to olefin
can be any ratio which gives a d~sired conversion and
selectivity. Preferably, the equivalent ratio of alcohol
or ether to haloalkene is 1.5:1 or above. More pre-
ferably the alcohol or ether to haloalkene ratio is 2.0:1
or greater. An equivalent with respect to the alcohol or
` ether, refers herein to that amount of alcohol or ether
which provides one mole of hydocarbyl radicals. In
particular, one mole of a dihydrocarbyl ether provides
two equivalents of hydrocarbyl radicals, while one of an
alcohol provides one equivalent of hydrocarbyl radicals.
31,912D-F -26-
-27- 1 25 ~
At least a stoichiometric ratio of carbon
monoxide to haloalkene is needed for this process to
give good selectivities and conversions.
The temperature used for the carbonylation
process has a significant effect on the conversions,
selectivities, catalyst productivity and catalyst life-
time. In practice, any temperature at which the de~sired
- conversions, selectivites, productivity, and catalyst
lifetime are achieved can be used. Preferable reaction
temperatures are between about 125C and 250C, with
170C to 240C being more preferred. In general, above
250C the rate of reaction significantly decreases.
Below 125C, the reaction rate is extremely slow.
The reaction pressure also has a significant
effect on the selectivities, conversions, catalyst pro-
ductivity and catalyst lifetime. Any reaction pressure
which gives the desired selectivities, conversions,
catalyst productivity and catalyst lifetime can be
used. Preferred pressures are between about 100 and
800 psi, (689 to 5512 kPa), with between about 300 and
600 psi (2067 to 4134 kPa) being most preferred. Above
800 psi (5512 kPA) the rate of reaction drops dramati-
cally and below 100 psi (689 kPa) the selectivity of
the reaction is very poor.
The flow rate over the catalyst can be any
flow rate which gives the desired conversions and
selectivities. In practice, the flow rate of carbon
monoxide is between about 15 gas volumes of carbon
monoxide per volume of catalyst per hour and 1500 gas
volumes of carbon monoxide per volume of catalyst per
hour. Preferably, the flow rate is between about 100
31,912D-F -27-
-28- ~5~"~
and 200 gas volumes of carbon monoxide per volume of
catalyst per hour.
It is preferable that the alcohol or ether and
haloalkene be vaporized by preheating before contacting
5 them with the carbon monoxide in the presence of the
catalyst, i.e. it is preferred to operate in the vapor
phase. The combined alcohol or ether and haloalkene feed
to the preheater is preferably between about 0.1 and 10
liquid volumes per volume of catalyst per hour. More
10 preferably the feed rate is between about a .5 and 1.5
liguid volumes of haloalkene and alcohol or ether per
volume of catalyst per hour.
This process can be performed in a batch or
continuous mode. Furthermore, the catalyst can be used as
15 a fixed bed catalyst or in a fluid bed. It is preferred
to use a continuous mode with a fixed bed catalyst.
In one preferred embodiment, methylmethacrylate
is prepared by contacting 2-chloropropene, carbon mono- d
xide and methanol, or dimethyl ether in the vapor phase
20 over a catalyst which comprises palladium on A10x/alumina
wherein the concentration of palladium on the support is
between about-l and 7 percent by weight. In this embodiment,
the catalyst is prepared by impregnating palladium
chloride onto the support. The catalyst is activated by
25 passing hydrogen gas over the supported palladium
chloride at a temperature of between about 240C and
280C for a period of between 1 and 3 hours. In this
embodiment, the contacting of the reactants takes place
at between about 170C and 240C under a pressure of 300
to 600 psi (2067 to 4134 kPa).
31,912D-F -28-
-29- ~5~ 9
The carbonylation process of this invention
results in a process for the preparation of acrylate
esters wherein the catalyst exhibits long lifetimes,
with good productivities and selectivities. The pro-
cess of this invention results in catalyst productiv-
ities of at least about 0.06 g of product per gram of
catalyst per hour, under more preferred conditions a
productivity of at least about 0.10 g of product per
gram of catalyst per hour, and under most preferred
conditions at least about 0.25 g of product per gram of
catalyst per hour. The process of this invention
results in selectivities toward ~-unsubstituted acryl-
ate ester of 70 percent or greater, under preferred
conditions, of 80 percent or greater, and under most
- 15 preferred conditions 85 percent or greater.
Referring to the carbonylation reaction, Con-
version refers to the amount of haloalkane converted to
products, and selectivities refer to the percentage of
acrylate esters in the products prepared.
D. Hydrogenation
The selective hydrogenation of alkynes amidst
major proportions of alkenes is a known reaction. For
example, the manufacture of unsaturated hydrocarbons
usually involves cracking higher hydrocarbons and
produces a crude product containing, as impurities,
hydrocarbons that are more unsaturated than the desired
product but which are very difficult to separate by
fractionation. A common example is the manufacture of
ethylene in which acetylene is a contaminant. In a
similar way, the formation of propylene is accompanied
by hydrocarbons of the empirical formula C3H4(e.g.
31,912D-F -29-
-30-
~ 25B~rfi'9
methyl acetylene and allene~, and the formation of
butadiene by vinyl acetylene. The content of the
undesired hydrocarbons depends upon the severity of the
conversion treatment, but is always too low to
- 5 permit their separation economically by conventional
means such as distillation. However, such highly
unsaturated hydrocarbons can be removed by hydrogenation
using process conditions and a carefully formulated
catalyst such that no significant hydrogenation of the
desired hydrocarbon takes place.
United States Patent 4,347,392 discloses a
hydrogenàtion catalyst which is palladium on alumina with
the average size of the palladium crystallites being at
least 50 angstroms. However, the preparation of said
catalyst is disadvantageous in that the catalyst must be
subjected to heat activation at a temperature of 600C to
1100C.
United States Patent 4,126,645 discloses a
hydrogenation catalyst which comprises palladium
supported on particulate alumina, the catalyst having a
surface area in the range of 5 to 50 m2/g, a helium
density of under 5 g/cm 3, a mercury density of under 1.4
g/cm 3 and a pore volume of at least 0.4 cm3/g, at least
0.1 cm3/g of which is in pores of radius over 300
Angstrom units, the palladium being present mainly in the
region o~ the`catalyst particles not more than 150
microns beneath their geometric surface. The alumina can
be a coating on the surface of a honeycomb.
United States Patent 4,410,g55 discloses a
hydrogenation catalyst support prepared by applying a
specified calcium aluminate material to a honeycomb.
- 31,912D-F -30-
-31- ~25B~"~
It would be desireable to have an improved
catalyst for the selective hydrogenation of alkynes and
dienes amidst a major proportion of alkenes. Surprisingly,
the catalyst of the present invention exhibits improved
selectivity and/or activity relative to commercially
available catalysts for the hydrogenation of acetylenic
impurities.
The hydrogenation process of the present
invention is a process for hydrogenating a hydrocarbon
composition comprising at least one alkene and at least
one alkyne,~ the process comprising contacting the hydro-
carbon composition with a catalyst of the present
inyention under reaction conditions to selectively hydro-
genate the alkyne without substantially hydrogenating the
alkene.
Two general types of gaseous selective hydro-
genation processes for purifying unsaturated hydrocarbons
have come into use. One, known as "front-end" hydro-
genatio~, involves passing the crude gas from the initial
cracking step, after removal of steam and condensible
organic matter, over a hydrogenation catalyst. The crude
gas normally contains a relatively large amount of
hydrogen, far in excess of that required to hydrogenate a
substantial part of the olefin present. Despite this
hydrogen excess, operation with sufficient selectivity to
give olefins of polymerisation quality is well established
- and catalyst lives of many years are obtained. In the
other type, known as "tail-end" hydrogenation, the crude
gas is fractionated and the resulting product streams are
reacted with hydrogen in slight excess over the quantity
~ required for hydrogenation of the highly unsaturated
hydrocarbons present. The tail-end hydrogenation is less
31,912D-F -31-
-32- ~25~u~9
critical than front-end hydrogenation in that at the
low hydrogen excess a runaway reaction is not possible;
` however, there is a greater tendency to deactivation of
the catalyst and formation of polymers from the highly
- 5 unsaturated hydrocarbons may occur as an alternative to
the hydrogenation thereof. Consequently periodic
regeneration of the catalyst is required.
When the process is a "front-end" hydro-
genation the temperature is suitably up to 250C, for
example 60-150C; the pressure is suitably in the
range 1-70 atm (101-7070 kPa), for example 8-40 atm
(808-4040 kPa); and the space velocity is suitably
in the range 100-20000, for example 5000-15000 hour 1,
that is, liters per liter o~ catalyst-filled space per
hour, calculated for 20C, 1 atm pressure. The volume
percentage composition of the gas fed to the catalyst
is suitably as follows for a process producing ethylene
and/or propylene as main products:
ethylene or propylene: 10-45
propylene or ethylene: up to 20 (when both are present)
higher hydrocarbons up to 2
acetylene and/or C3H4:0.01 to 2
hydrogen: 5-40
unreactive gases (e.g. alkanes, nitrogen):balance
For long catalyst life without regeneration the hydro-
` gen content is preferably at least 5 times by volume as
much as the content of acetylene and C3H4.
When the process is a tail-end hydrogenation
the temperature is suitably in the range 40-150~C; the
31,912D-F -32-
-33~ 1 ~5 ~2~
pressure is suitably in the range 1-70 atm (101-7070
kPa), for example 8-40 atm (808-4040 kPa); and the
space velocity is suitably in the range 500-7000 hour 1,
that is, liters of gas per liter of catalyst-filled
space per hour. The hydrogen content should be at
least sufficient to hydrogenate to mono-olefin all the
highly unsaturated hydrocarbons present and is prefer-
ably from about 1.0 to about 1.5 times that content for
acetylene. The life of the catalyst between regener-
ations is longer the higher the hydrogen content of thegas, but this advantage is counter-balanced by the
expense of separating and recycling greater quantities
of saturated hydrocarbon. The gas passed over the
catalyst typically contains up to about 6 percent (for
example 0.1 to 3.0 percent) of highly unsaturated
hydrocarbons and at least 50 percent, sometimes over 95
percent, of the desired mono-olefin or conjugated
diolefin.
When the process is a tail-end liquid-phase
selective hydrogenation the temperature is typically
0-50C, the pressure up to about 50 atm ~5050 kPa),
and the space velocity typically 5-40 kg. per hour per
liter of catalyst-filled space. The li~uid hydrocarbon
suitably trickles downwards over the catalyst in a
substantially stationary hydrogen atmosphere.
Whichever type of hydrogenation is used, it
appears to be advantageous to have present a small
quantity of carbon monoxide. In a front-end hydro-
genation the proportion of carbon monoxide is suitably
0.03 to 3.0 percent v/v of the total gas mixture. Such
a content commonly enters in as a by-product of the
initial cracking reaction.
31,912D-F -33-
-34- ~ ~5 ~
In a tail-end hydrogenation the proportion is
suitably in the range 4.0 to 500 ppm v/v; it may be
added deliberately if fractionation of the crude gas
has removed it or left too little of it.
The composite hydrogenation catalyst typi-
Gally is prepared using a core support material having
a surface area of from about 5 to about 400 m /g, and
- preferably from about 30 to about 200 m2/g
Catalysts which can be employed in the hydro~
genation process of the present invention include
catalysts comprising known catalytic materials for the
selective hydrogenation reaction which catalytic mater-
ials are supported on an alkoxide-modified support.
Examples of said catalyic materials include, for example,
materials comprising palladium nickel, platinum, osmium,
rhodium, and others, with palladium being preferred. A
promoter is optionally employed. Example of typical
promoters include Mo, Fe, Cr and metals of Group IB.
The catalytic material is employed in a
catalytic amount. Preferably, from about 0.01 to about
1 weight percent catalytic metal is employed in the
composite catalyst for selective hydrogenation, more
preferably from about 0.02 to about 0.5 wt percent
catalytic metal is employed.
The composite catalyst is prepared according
to known methods of applying a catalytic material to a
support. This may be effected by a dry procedure, such
as sputtering, but is preferably effected by a wet pro-
cess, in which a solution of a palladium compound, for
example the chloride or nitrate, is applied to the
31,912D-F -34-
-35~ 125~4~
support by, for example, dipping or spraying. Spraying
is preferred in order to obtain more reliably the
desired uptake of palladium. Penetration of palladium
can be controlled by suitable adjustment of the acidity
of the solution, the acidity level being dependent on
the alkali-content of the alumina. If desired the
deposition of the palladium can be aided by a pre-
cipitant such as a slow-acting alkali (~or example
urea) or a reducing agent.
A preferred hydrogenation catalyst has the
catalytic metal located below the surface of the
alkoxide-modified composite support, and is prepared
using an acidic solution of an acid such as, for example,
HF, which is preferred, or citric or other acids. For
example, the typical concentration of HF in the catalytic
metal-containing solution is from about 1 to about 8
weight percent. The average penetration of palladium
into the support preferably is from about 0.01 mm to
about 1 mm below the surface of the composite catalyst.
The method of preparing such a penetrated layer catalyst
is well known. See, e.g., Journal of Catalysis, V. 51,
pp. 185-192 (1978).
After application of the palladium content to
the support, it is drained, may be dried at a tempera-
ture in the range 25C. to 150C., conveniently atabout 100C., and may, without or with a distinct
drying step, be heated to decompose the palladium com-
pound, suitably at a temperature up to 500C., espe-
cially in the range 150C. to 450C. The pieces may be
treated with hydrogen to complete reduction to palla-
dium metal for example during the heating step just
mentioned and/or during an additional heating step (in
31,912D-F -35-
-36- ~ 2 5 ~r,~ ~
which the temperature should be in the range 25 C. to
450 C.) after the first heating step but before use.
If there is not preliminary reduc-tion step, reduction
takes place under the reducing conditions in the selec-
tive hydrogenation process. If the catalyst is reducedbefore use it may be stored under an inert atmosphere
but should preferably not be kept for prolonged periods
in hydrogen. If desired, the composite catalyst can be
reduced in the known manner using a known reducing
agent such as hydrazine or sodium borohydride, NaBH~.
The use of NaBH4 as a reducing agent is well known.
See, e.g., Catal. Rev. - Sci. Eng~, 14(2), 211-246
(1976).
For the purposes of the hydrogenation process
of the present invention, the terms conversion and
selectivity are as defined in Applied CatalYsis~ V~2
pp. 1-17 (1982). Surprisingly, the hydrogenation
catalyst of the present invention produces relatively
little green oil, i.e. alkyne oligomers.
The following examples and comparative experi-
ments are given to illustrate the invention and should
not be construed as limiting its scope. All parts and
percentages are by weight unless otherwise indicated.
Specific Embodiments
Preparation of Alkoxide-Modified Supports
Preparation 1
A solution 4.5 g of Al[OCH(CH2CE3)(CH3)]3
(obtained from Alfa Products, a Division of Morton
Thiokol, Inc.), in 20 ml of hexanes is added to a
suspension of 10 g of y-Al2O3 core support material
(obtained from Strem Chemicals, Inc.), and having a BET
31,912D-F -36-
-37-
surface area of 100 m2/g in 125 ml of hexanes to form a
mixture. The mixture is stirred for 2 hours at room
temperature under an inert atmosphere. Then the hexanes
are removed under vacuum to yield a white powder. The
powder is calcined in air at 450C for 15 hours to form
an AlOx/y-Al2O3 alkoxide-modified support having a BFT
surface area of 120 m2/g. The weight ratio of AlOX to
y-aluminum is approximately 0.05. The BET surface area
of the modified support is 120 m2/g, versus 100 m2/g
for the unmodified alumina. Thus, the alkoxide modi-
fication does not significantly alter the overall
surface area of the support. Other physical data for -
the treated and untreated aluminas of Preparation 1 are
as follows:
~alumina A10x/y-alumina
pore volume 0.27 0.23
(cc/g)
average pore 60 45
size (A)
For the purposes of the present invention,
the subscript "x" in the term A10X represents the
relative ratio of oxygen atoms in an alkoxide-modified
support to the metal of the metal alkoxide. It is
believed that the metal(s) of the metal oxide layer of
the modified support are in the highest oxidation
state, based on calcination conditions. While this
example uses A10x, additional examples of prefered
metals of the metal alkoxide are listed hereinabove.
31,912D-F -37-
-38-
~25~ 9
Preparation 2
The procedure of Preparation l is followed
except that the precursor metal alkoxide is
Ti[OCH(CH3)2]4, and the final product alkoxide-modified
support is TiOX/~-Al2O3-
Preparation 3
The procedure of Preparation 1 is repeatedexcept that -the precursor metal alkoxide is
Ta~OCH(CH3)2]4, and the alkoxide-modified support is
TaOx on y-Al2O3.
Preparation 4
The procedure of Preparation l is repeated with
the following exceptions:
a) 9 g of the aluminum alkoxide is employed;
b) the core support material is 20 g of 30-80
- mesh y-Al2O3 (obtained from United Catalyst, Inc. under
the designation T-374 and having a surface area of
approximately 100 m2/g) and is suspended in 50 ml of
hexane; and
(c) the powder is calcined at 550C for 5
hours.
The resulting alkoxide-modified support con-
tains 5 weight percent (~ased on aluminum~ of aluminum
oxide ~AlOX) coating.
Preparation 5
The procedure of Preparation 4 is repeated
expect that 50 grams of the core support material are
treated with 4.5 grams of the aluminum alkoxide~ and the
powder is calcined at 450C in air over night.
31,912D-F -38-
-39~ 1~5~49
Example l - Methanation Catalyst Preparation
Five grams of the support of Preparation 1 are
added to a 100 ml solution of 0.64 g of RuCl3 (1-3 H20)
in H20. The mixture is stirred for an hour and the
water is removed under vacuum with steam heat. The
solids are dried overnight at 110C in air. Analysis
indicates that the solids contain 5 weight percent Ru.
General Methanation Reaction Procedure
A 16-inch (41 cm) long piece of 9/16 inch
(1.43 cm) tubing of type 316 stainless steel is employed
vertically as a reactor. The reactor is equipped with
a means for tèmperature control, and has 1 g of catalyst
held in place by quartz wool in the center of the
reactor. The catalyst is reduced in situ at 400C for
15 hours with hydrogen at 50 cc/min. Then the reactor
is cooled to 300C in flowing hydrogen gas. Then a
feed stream consisting of 2 moles hydrogen per mole of
C0 is fed to the reactor under a pressure of 1 atmosphere
(14.~ psig) at 100 cc/min (gas hourly space velocity =
6000/hr). The product stream is analyzed using gas
chromatographic methods capable of detecting C1-C5
hydrocarbons, C1-C5 alcohols, H2, Co, and C02.
Examples 2-5 and Comparative Experiments 1-4
The General Methanation Reaction Procedure is
followed for Examples 2-5 and Comparative Experiments
1-4, and each run is conducted for a 24-hour period.
` The results of each run are summarized in Table I.
Example 2
The catalyst of Example 1 is employed.
.
31,912D-F -39-
-40_ 125~
Comparative Experiment l
The catalyst is 5 weight percent Ru on the
~-Al2O3 core support material of Preparation l with no
alkoxide modification.
Example 3
The catalyst is 5 weight percent Ru on the
support of Preparation 2.
Comparative ExPeriment 2
The catalyst is 5 weight percent Ru on TiO2,
10the untreated Tio2 having a BET surface area of 100 m2/g.
Example 4
The catalyst is 5 weight percent Ru on the
support of Preparation 3.
Comparative Experiment 3
15The catalyst is 5 weight percent Ru on Ta205,
the untreated Ta2O5 having a BET surface area of 5 m2/g.
TABLE I
Methanation Results with 5 Weight
Percent Ruthenium Catalysts
20Selectivity
Conversion to Methane
Run Catalystof CO (mole %) (mole %)
Ex. 2 Ru/AlOx/y-Al~203 99 100
C.E. 1 Ru/y-Al2O3 62 99
Ex. 3 Ru/TiOx/y-Al2O398 100
C.E. 2 Ru/Tio2 58 100
Ex. 4 RU/Taox/y-Al2o397 100
C.E. 3 Ru/Ta2O5 17 37
31,912D F -40-
-41- ~5~ 9
The results summarized in Table I indicate that
the catalyst of the present invention unexpectedly and
significantly outperforms, under identical conditions,
conventional catalysts supported on materials used as the
core support material of the catalyst of the present
invention.
Example 5 and Comparative Experiment 4
Example 2 and Comparative Experiment 1 are
repeated except that the catalyst has 1 weight percent
ruthenium. The results are summarized in Ta~le II.
TABLE II
Methanation with 1 Weight Percent
Ruthenium Catalyst
Selectivity
Conversion to CH
Run Catalyst of Co (mole O (mole4%?
Ex. 5Ru/AlOx/y-Al2O3 90 99
C.E. 4 Ru/y-Al2O3 3 81
Surprisingly, at the lower catalyst loading,
1 weight percent ruthenium, the catalyst of the present
invention significantly outperforms the e~uivalent
catalytic metal on the conventional support. More
surprisingly, a loading of 1 weight percent ruthenium
on an alkoxide modified support outperforms a conven-
tional catalyst having a loading of 5 weight percentruthenium (see Comparative Experiment 1).
31,912D-F -41-
-42~
Comparative Experiment 5 - Comparative Olefin Metathesis
Catalyst Preparation
Three grams of the T-374 alumina employed in
Preparation 4 is added with stirring to a 30 ml aqueous
solution of perrhenic acid for 1 hour. The acid per-
rhenic solution contains 0.096 grams of rhenium metal.
The mixture is evaporated to dryness on a steam bath.
The dry powder is calcined in a 50 ml per minute stream
of air at 575QC for 9 hours, and for 3 hours in a 50 ml
per minute stream of nitrogen. The calcined powder is
then cooled to room temperature under a nitrogen atmos~
phere. Analysis by plasma emission spectroscopy indi-
cates a 2.96 weight percent rhenium loading.
Example 6 - Olefin Metathesis Catalyst Preparation
The catalyst is prepared using the procedure
of Comparative Experiment 5 except that the support is
2.1 grams of the modified gamma alumina of Preparation 4,
and the perrhenic acid solution contains 0.13 grams of
rhenium and 50 ml water. Analysis by plasma emission
spectroscopy indicates a 3.01 weight percent rhenium
loading.
General Olefin Metathesis Reaction Procedure
A reactor is employed which is similar to the
reactor of the general methanation reaction procedure
except that the diameter is 3/8 inch (0.9 cm). The
catalyst is activated ln situ at 550C for 2 hours with
nitrogen at 50 ml per minute. The reactor is then
cooled to 87C in flowing nitrogen. A feed stream is
then fed to the reactor under a pressure of 1 atmosphere
gauge (101 kPa) and a gas hourly space velocity of from
100 to 1000 hours 1 The product stream is analyzed
using a capillary gas chromatograph.
31,912D-F -42-
-43- ~25~
Comparative Experiment 6 and Exam~le 7
The general olefin metathesis reaction pro-
cedure is followed. The feed stream is a mixture of 25
mole percent propylene in helium. ~ata obtained using
the comparative catalyst of Comparative E~periment 5 is
summarized in Table III. Data obtained using the
catalyst of Example 6 is summarized in Table IV. In
each case, the conversion is monitored by the disap-
pearance of propylene *om the reactor effluent.
Ethylene and 2-butenes are the only products observed.
The conversion is thermodynamically limited to 37
percent under the given reacton conditions. The con-
version is calculated according to the formula:
moles of propylene converted
15 % conversion = moles of propylene fed x 100
TABLE III
Propylene Metathesis Over Re2O7/A12O31
Time (H) GHSV (H 1)Conversion (%)
1 100 17.7
16 100 13.8
23.5 100 12.0
23.6 500 3.6
23.8 800 1.6
42.7 100 8.8
46.8 ~100 9.6
1) 1.0 gram catalyst, 2.96 weight percent Re, 30-8Q mesh,
360 K, 0.1 MPa.
31,912D-F -43-
~~44~ 1 Z5
TABLE IV
Propylene Metathesis over Re207/Modified A12032
Time ~H) GHSV (H 1)Conversion (%)
50.5 110 27.2
68 300 14.6
500 6.5
70.8 -1000 3.4
71.5 100 16.1
73.8 100 17.6
2) 1.0 gram catalyst, 3.01 weight percent Re, 5.0
weight percent Al coating, 30-80 mesh, 360 K, 0.1 MPa.
From ~ables III and IV it is observed that the
catalyst of the~present invention unexpectedly gives
higher convers~on over a longer period of time as
compared to a comparative catalyst prepared using a
conventional support material.
Comparative Exp~riment 7 and Experiment 8
Following the General Olefin Metathesis
Reaction Procedure, the reactor is fed pure isobutylene
at 10 millileters per minute. Only oligomerization of
isobutylene is observed. After a period of time, as
mentioned hereinbelow, the propylene/helium feed of
Example 7 is resumed and the isobutylene feed is dis-
continued. Significant deactivation of the catalyst of
31,912D-F -44-
-45- ~25~z~9
Comparative Experiment 6 is observed after isobutylene
has been fed to the reactor for 5 hours. Specifically,
the activity for the metathesis reaction decreases 80
mole percent, based on propylene converted. After 15
hours of prior isobutylene feed, the catalyst is totally
deactivated. In contrast, the catalyst of Example 7
exhibits much less deactivation with isobutylene and
after 23 hours of prior isobutylene feed the activity
decreases by only 25 percent. Thus, the catalyst of
the present invention is shown to be less prone -to
deactivation.
General CarbonYlation Reaction Procedure
The reactor is a Hastelloy B 1/2 inch (1.27
cm) diameter fixed bed tubular reactor. The fixed bed
of the reactor is created by first loading 5.0 ml of
~-alumina pellets, then 10.0 ml of 10-20 mesh catalyst,
and finally 3 ml of quartz chips. The catalyst is
first reduced under flowing hydrogen at 400 cc per
minute at 250C for 2 hours. The reaction is carried
out at a temperature of 210C, a total pressure of 600
psig (4235 kPa), a carbon monoxide flow rate of 25 cc
per minute (GHSV = 150), and at a liquid feed rate of
7.2 cc per hour. The molar ratio of the liquid feed is
2.0 methanol: 0.2 cyclohexane (internal standa.rd): and
1.0 2-chloropropene.
Example 9
Preparation of Carbonylation Catalyst
An 11.1~ g sample of an alkoxide modified
support prepared according to the procedure of Prepara-
tion 4 is heated to 120C and is held at that tempera-
ture for several hours. A solution having a pH of 3 is
prepared by adding 0.57 g of PdC12 to 15 ml of deionized
water and 1.2 ml of concentrated hydrochloric acid, and
31,912D-F -45-
l;~S~
-46-
heating the resulting mixture to 70C. The heated
support is contacted with the hot palladium chloride
solution using the incipiant wetness technique. The
impregnated palladium catalyst is allowed to cool to
room temperature and then is heated to 120C for 2
hours in a stream of air. The catalyst is loaded into
the reactor and is reduced as described in the general
carbonylation reaction procedure. Measurements of
crystallites sized by hydrogen chemisorption show that
the catalyst has a palladium dispersion of 56 percent
and a loading of 3.0 weight percent palladium based on
total catalyst weight. The results which are obtained
usin~ this catalyst in the General Carbonylation Reac-
tion Procedure are summarized in Table V.
Comparative Experiment 8
Comparative Carbonylation Catalyst Preparation
The comparative carbonylation catalyst is
prepared using a 3.2 weight percent Pd on y-alumina
catalyst available from the Calsicat Division of
Mallinckrodt, Inc. under the designation: sample #
21C-095B.
The catalyst is reduced according to the
procedure of Example 9. The palladium dispersion is 38
percent. The results obtained using this catalyst in
the General Carbonylation Reaction Procedure are sum-
marized in Table V.
31,912D-F -46-
~.25~
-47-
TABLE V
CARBONYLATION
Ex. 9 C.E. 8
Time (~1 ~ Converslon Time (h)% Conversion
522 52 3 50
49 4 49
42 ~ 45 7 47
43 25 36
38 27 38
1071 34 31 36
28 48 28
100 28 ~0 25
24
Inorganic [Cl ~ in product stream:
Ex. 9 - < 120 mg/l
C.E. 8 - > 360 mg/l
It is apparent from Table V that the carbonyla-
tion catalyst of the present invention exhibits greater
activity and has a longer lifetime than the comparative
catalyst. It is noted that use of the catalyst of
Example 9 results in a lower chloride ion concentration
in the product stream, i.e. the product stream advan-
tageously is less corrosive when employing the catalyst
of Example 9.
Comparative Experiment 9
Comparative Hydrogenation Catalyst
A 10 cc sample of the untreated T-374 alumina
of Preparation 4 is impregnated for 15 minutes with an
excess of an aqueous solution of palladium nitrate
which contains 0.08 weight percent palladium. Then,
the impregnated support is separated from the excess
solution and is rinsed with distilled water. The
31,912D-F -47-
-48- l~S~
resulting wet catalyst is then placed in a solution of
NaBH4 at (least 10 molar equivalents based on palladium)
to reduce the palladium ions to palladium metal. The
wet catalyst remains in solution for a period of thirty
minutes. The excess solution is then separated from
the catalyst pellets and the pellets are rinsed with
acetone, to deactivate any residual NaBH4, and are
allowed to dry in air. The resulting catalyst has
about 0.05 weight percent Pd by analysis.
Example 10
Hydrogenation Catalyst Preparation
The procedure of Comparative Experiment 9 is
repeated except that the catalyst support is the alkox-
ide modified support of Preparation 5.
ExamPle 11
Hydroqenation Catalyst Having Sub-surface Palladium
The procedure of Comparative Experiment 9 is
repeated except that the catalyst support is the alkox-
ide modified support of Preparation 5. An additional
exception is that the palladium solution contains four
weight percent hydrofluoric acid.
The catalyst of Example 11 is in the form of
cylindrical pellets 1/8" by 1/8"(0.3 x 0.3 cm~. The
color is gray to gray/white. Cutting a pellet in half
exposes a dark-gray to black band of reduced palladium
- which is approximately 0.1 to 0.5 mm below the surface.
The band is very narrow, having a width of approximately
0.05 to 0.1 mm. The light-gray coloration may penetrate
to about 1 mm below the surface and the inside of the
pellet is white. The alkoxide treatment deposits one
weight percent, based on aluminum, of A1203 on the
31,912D-F -48-
lZS~
-49-
surface of the gamma alumina core support. The impr.eg-
nation using 0.08 weight percent palladium and a four
weight percent HF solution produces a palladium loading
of about 0.05 weight percent.
General Hydrogenation Reaction Procedure
Ten cc of catalyst is placed into a 300 cc
Berty reactor. A feed stream containing 0.5 mole
percent H2, 0.5 mole percent C2~2, 5 ppm C0, and approx-
imately 99.5 mole percent ethylene (containing small
amounts of ethane and methane) is introduced to the
reactor at a rate of 0.5 liters per minute (gas hourly
space velocity equal 3,000 hours 1) and a pressure of
250 psig (1824 kPa). The reactor effluent is analyzed by gas
chromatograph. The conversions of acetylene and hydro-
gen are measured directly, as is the selectivity toethane and C4 compounds. The change in ethylene con-
- centration and green oil production values are calculated,
assuming no hydrogen is consumed in the green oil,
using the method of Battiston et al. in Applied catalysis,
Vol. 2, pages 1-17 (1982). The results in mole percent
are summarized in Table VI.
31,912D-F -49-
~25~34~
-50-
TABLE VI
Hydrogenation with
Pd on y-Alumina Catalyst
Conversion Selectlvity
Exam- Temp
ple (C) C2H2 H2 C2H4 C2H6 C4's* G0*
33.1 19.6 41.5 8.8 8.5 41.5
C.E.9 50 54.4 32.4 42.5 6.7 11.6 39.5
80.1 49.5 45.6 6.1 12.1 36.g
89.7 50.1 38.8 8.4 12.1 40.9
Ex.10 50 95.6 75.1 31.512.6 16.7 28.4
97.4 84.0 36.126.7 15.2 22.4
87.2 53.0 41.5 8.3 16.2 34.2
Ex.11 50 93.8 69.4 36.121.4 12.4 30.4
95.8 83.9 26.433.6 14.6 26.3
*Expressed as moles of C2H2
G.O. = green oil.
From Table VI it can be seen that the catalysts
of the present invention (Examples 10 and 11) are more
active and produce relatively less green oil, or
oligomers, as compared to the catalyst of C.E.9., which
has a conventional support.
Comparative Experiments 10-12 _
Comparative catalysts are prepared using the
methods of Examples 10 and 11, except that the alumina
31,912D-F -50-
-51- ~25B~s~
core support is ~-alumina having a surface area of
about 4 m2/g. (The ~-alumina is obtained from Harshaw
Chemical Company under the designation Al-3980.)
Specifically, the catalyst of Comparative Experiment 10
is prepared in a manner similiar to the manner in which
the catalyst of Example 10 is prepared. The catalyst
of Comparative Experiment 11 is prepared in a manner
similiar to the manner in which the catalyst of Example
11 is prepared.
The catalysts of Comparative Experiments
10-11 are employed in the General Hydrogenation Reac-
tion Procedure, and the results are summarized in
Table VII.
TABLE VII
Hydrogenation with
Pd on ~-Alumina Catalyst
Conversion Selectivity
Exam Temp
ple (C) C2H2 H2 C2H4 C2H6C4's* GO
2040 20.6 19.1 28.837.5 5.0 30.
C.E.10 50 32.6 29.4 24.735.7 9.0 32.2
45.9 41.7 21.735.611.1 32.9
24.3 15.3 50.512.8 6.9 35.8
C.E.ll 50 43.8 25.8 42.410.8 10.9 40.9
67.1 42.6 44.913.011.0 37.0
*Expressed as moles of C2H2.
GØ = green oil.
31,912D-F -51-
-52- ~ ~S ~
A comparison of the results of Tables IV and
VII surprisingly indicates that alkoxide-modified
catalysts with the ~-alumina core support having a
surface area of ~ m2/g are not drastically improved as
in the case when using ~-alumina having a surface area
.of 100 m2/g as the core support material.
Example 12 An~ Comparative Experiment 12
Extended Hydrogenation Run
The catalyst of Exàmple 11 and a comparative
catalyst are employed in the General Hydrogenation
Reaction Procedure. The comparative catalyst is a
commerical catalyst available under the designation
G-58B, and is available from United Catalysts, Inc.
Two runs are done for each catalyst. Fresh catalysts
are used in the first runs. The catalysts are regener-
ated prior to the second runs. The summarized results
indicate that the catalyst of the present invention is
generally superior to the commercial catalyst regarding
conversion of acetylene and selectivity to ethylene.
.
A review of the Examples indicates that
catalysts employing an alkoxide-modified support com-
prising alumina on alumina having a surface area greater
than about 5 m2/g surprisingly out perform similar
catalysts having conventional supports. This is unex-
pected in that a metal oxide/metal oxide support having
the same metal, e.g. alumina on alumina, would behave
in a manner similar to an untreated support. Thus,
one preferred embodiment of the present invention is
a catalyst composition wherein the alkoxide-modified
31,912~-F -52-
-53-
~S~r~
support employs the same metal in the metal alkoxide
and the core support.
The preceding examples serve only to illus-
trate the invention and its advantages, and they should
not be interpreted as limiting since further modifica-
tions of the disclosed invention will be apparent to
those skilled in the alt. All such modifications are
- deemed to ~e within the scope of the invention as
defined by the following claims.
31,912D-F -53-
