Note: Descriptions are shown in the official language in which they were submitted.
FD _13/1114/1114/A
BACKGROUND OF THE INVENTION
Field of the Invention
This invention relates to an improved catalytic
hydrogenation process for preparing butanediol from butynediol
and, more particularly it is concerned with the first stage of
a two stage process for obtaining butanediol of high quality
using as a catalyst Raney nickel having a molybdenum compound
adsorbed on the nickel.
Description of the Prior Art
Butanediol is prepared in industry by catalytic
hydrogenation of a butynediol solution, as described in detail
in a number of U.S. patents, as for example, 2,950,326;
2,953,605; 3,449,445; 3,479,411; 3,691,093; 3,759,845 and
3,950,441. The starting butynediol solution is obtained by a
catalytic ethynylation reaction between aqueous formaldehyde
and acetylene, as described in U.S. 3,920,759.
Catalytic hydrogenation of butynediol solutions to
butanediol may be carried out in two stages, that is, a
relatively low pressure and/or temperature stage and a higher
pressure and/or temperature stage. The first stage may be
effected in a continuous manner using a stirred slurry of a
Raney-nickel catalyst which may contain small amounts of
copper as an activator, as described in U. S. 3,950,441. This
reaction proceeds in two reduction steps. First, butynediol
is reduced to butenediol, and then butenediol is hydrogenated
Fl)N .13/1114/1114/A
to butanediol. Some of the butynediol starting material,
however, is reduced concurrently to form an isomer of
butenediol, which is 4-hydroxybutyraldehyde (HBA). The HB~
by-product hydrogenates more slowly than butenediol.
Furthermore, ~BA forms an acetal with butanediol. HBA and its
acetal can undergo side reactions forming non-volatile
residues.
These aldehydes and acetals, together with unreduced
butenediol, when present in substantial amounts in the
butanediol, represent a poor quality product. Accordingly, it
has been necessary to include a second hydrogenation stage, or
finishing stage, in the process, which operates at higher
pressures and/or temperatures than the first stage, in order
to convert these residual intermediates to butanediol product.
Unfortunately, however, this aldehyde and acetal can react
also under the second stage conditions with any unremoved
formaldehyde present in the butynediol solution to ~orm
condensation products, which, upon hydrogenation, give 2-
methyl-1,4-butanediol (MBlD). The MBlD by-product cannot be
converted to butanediol during finishing, and it is also
difficult to separate from the butanediol product during the
final distillation step of the process.
The Raney nickel catalyst used in the low pressure
stage i5 a well known hydrogenation catalyst, which was
described originally in U. S. Patent 1,63~3,190 and in J.A.C.S.
54, 4116 (1932). Subsequently, improved Raney nickel
catalysts have been developed containing other metallic
constituents. The Raney nickel catalysts are prepared by
alloying nickel with aluminum and leachin~ out the aluminum
with alkali to expose the nickel as porous, finely-divided,
solid particles, in which state nickel is an effective
hydrogenation catalyst.
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~ 3 ~
., ,
By providing a starting alloy of nickel, molybdenum and aluminum,
and leaching out the aluminum in the usual manner, the art has provided
alloyed Raney nickel-molybdenum catalysts. Preparation and use of such
alloys are described in United States Patent 2,948,687, and in Bull. Soc.
Chim. 208 (1946). However, as will be discussed and described hereinafter,
such alloyed modifications of Raney nickel are unsuitable hydrogenation
catalysts in comparison with improved Raney nickel catalysts prepared in
accordance with the invention for the low pressure reduction of butynediol
to butanediol.
Accordingly, the present invention seeks to provide an improved
catalytic hydrogenation process for the preparation of butanediol of high
quality.
Additionally, this invention seeks to provide a low pressure, low
temperature catalytic hydrogenation stage for making butanediol from
butynediol in which less aldehyde and acetal by-products are produced.
A feature of the invention is the provision of an improved Raney
nickel catalyst for use in the low pressure, low temperature hydrogenation
stage consisting essentially of nickel particles having adsorbed thereon a
molybdenum compound.
A particular feature of this improved catalyst is that is produces
a higher quality of butanediol, i.e. less aldehyde and acetal and conden-
sation products thereof, and thereby increases the quality of butanediol ob-
tained in the process.
Surprisingly, this catalyst has also been found effective for
reducing carbon-oxygen double bonds.
Thus this invention provides an improved Raney nickel catalyst
comprising Raney nickel solids having adsorbed thereon a molybdenum compound
in an amount of about 0.5-15 parts by weight molbdenum per lO0 parts of the
Raney nickel solids.
In an alternative aspect, this invention provides a process for
reducing carbon-carbon or carbon-oxygen multiple bonds by means of hydrogen
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gas and a catlyst, wherein the catalyst comprises Raney nickel having a
molybdenum compound adsorbed on the nickel in an amount of about 0.5 to 15
parts by weight molybdenum per 100 parts by weight of Raney nickel solids.
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FDI 113/1114/1114/A ~ 961
Summary of the Invention
These and other objects and features of the invention
are achieved hereby by providing a catalytic hydrogenation
process for the preparation of butanediol from butynediol
using an improved Raney-nickel catalyst having a molybdenum
compound adsorbed on the Raney nickel solid. The improved
catalyst is prepared by stirring Raney nickel in liquid
suspension with a suitable amount of a molybdenum compound.
The molybdenum compound may be added as a solid, a dispersion
of the solid or in solution form. Agitation is continued and
molybdenum compound is adsorbed on the nickel particles. The
catalyst consists essentially of about 0.5-15 parts by weight
of molybdenum adsorbed per 100 parts by weight of Raney nickel
solids. Other metals, such as copper, chromium, cobalt,
tungsten, zirconium, platinum and palladium also may be
included in the catalyst composition. These additional metals
may be added in the same manner as the molybdenum compound, so
that a compound of suchmetals also is adsorbed on the nickel,
or they may be originally present in alloy form as part of the
Raney nickel.
Using the improved Raney nickel catalysts of the
invention, much lower amounts of aldehyde, acetal and
condensation products are produced during the low pressure
hydrogenation process, and thus the quality of butanediol is
substantially and significantly enhanced in comparison with
other known processes, using different catalysts.
In accordance with the invention, suitabl~ about 0.5-
15 parts by weight of molybdenu~ per 100 parts by weight of
Raney nickel solids present is used as the catalyst
FDN 13/1114/1114/A 11~961
composition. Preferably, about 2-8 parts by weight and,
optimally, about 4 parts by weight molybdenum are used. In
practice, the amount of molybdenum in the catalyst may be
determined, after additions of known amounts of the molybdenum
compound, by analysis of residual molybdenum still in
suspension after stirring for given periods of time.
Alternatively, the catalyst itself may be analyzed for nickel
and molybdenum content.
The reaction mixture for hydrogenation is prepared
with a crude aqueous butynediol solution containing about lO-
60% by weight butynediol, preferably about 25-50%, and
optimally, about 35%. The solution also contains small
amounts of unremoved formaldehyde, and dissolved salts. The
solution is buffered with sodium acetate to a pH of about 4-
lO, preferably ~bout 5-8, and, optimally, about 7.
The solution may be given an ion-exchange treatment
to remove salts which would give residues upon distillation,
although this is not an essential part of the process.
The catalyst may be slurried with the butynediol
solution in widely varying amounts. Usually about 1-30% by
weight of catalyst per weight of butynediol will be employed,
with about 3-12~ being preferred, and, about 6% being more
nearly optimum. Of course, at lower concentrations of
catalyst, its effectiveness is reduced; but at high
concentrations the cost of use of the catalyst increases more
rapidly, as does the difficulty of separation of spent
catalyst from the reaction product mixture.
FD~ .13/1114/1114/A ~112~
The reaction mixture is agitated at a temperature of
about 15-100C., preferably at about 50-70C., and
optimall~, at about 60C. The reactor is maintained under a
hydrogen pressure of about 15-600 psig., preferably about 200-
400 psig., and, optimally, about 300 psig. Higher pressures
favor more rapid and complete hydrogenation, but require more
expensive reactor equipment.
The product of this low pressure hydrogenation stage
is an aqueous solution of butanediol containing only small
amounts of aldehydes, acetals, condensation products and
unreduced butenediol, which amounts, however, are much lower
than those observed in two-stage processes using other Raney
nickel catalysts, unactivated or activated with metallic
constituents, such as copper and the like. Even Raney nickel
catalysts containing alloyed molybdenum, which was prepared by
leaching aluminum out of an alloy of nickel, molybdenum and
aluminum with alkali, produce much higher by-products in this
process.
The reaction mixture of this hydrogenation stage then
is subjected to a finishing high pressure and/or high
temperature hydrogenation stage, as in the past, to convert
the very small amount of intermediates to butanediol. In such
a typical two-stage operation, as described in U. S.
3,950,441, the reaction mixture is allowed to settle, and the
liquid is separated from the catalyst and charged to an
intermediate storage zone for pumping into the subsequent high
pressure stage of the process. From the intermediate storage
zone, the solution is charged to a high pressure reactor which
may be maintained at about 2,000 to about 3,000 psig at a
temperature of about 130 to about 16CC. A stream of
FD~ 113/1114/lii4/A 1~2~961
hydrogen is simultaneously charged under pressure to the
reactor. The reactor is filled with a fixed bed of a suitable
catalyst, which is di~ferent than that used in the low-
pressure step. A typical high pressure catalyst, as described
in said patent, comprises about 12 to 17% by weight nickel, 4
to 8% by weight of copper and 0.3 to 1.0% by weight of
manganese supported on alumina or silica gel carrier.
The improved Raney nickel catalyst used herein is
prepared starting with commercial available Raney nickel,
which is usually a suspension of about 50% by weight of nickel
kept under water. The commercial slurry may be diluted, if
desired, to provide a stirrable concentration of the Raney
nickel for reaction with the molybdenum compound.
A suitable amount of the molybdenum compound, as a
solid, dispersion or a solution thereof is added to the Raney
nickel suspension with stirring. Typical molybdenum compounds
include various molybdenum salts and oxides, including
ammonium and alkali molybdates, molybdic trioxide and the
like. Preferably, the molybdenum compound is at least
partially soluble in water.
The mixture is stirred at room temperature for a
period of time which is sufficient to adsorb most of the
molybdenum compound onto the Raney nickel solids. Usually,
about lO minutes to 24 hours is suitable for this purpose, and
about one hour generally is ample to adsorb the desired amount
of the molybdenum compound onto the nickel. The resulting
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FD~ .l13/1114/1114/A l~Z296~
aqueous suspension then is used as such as the catalyst in the
hydrogenation process. Any excess molybdenum compound present
in suspension or solution does not interfere with the
hydrogenation process, and, therefore, filtering of the
catalyst suspension is unnecessary.
Other high pressure and/or high temperature
procedures and conditions may be used, also, to finish
hydrogenation of the low pressure stage product. Such other
processes are not limited to a fixed bed catalytic reaction,
or to any particular catalyst composition.
The finishing high pressure stage will produce
relatively little additional butanediol since the aldehyde
content in the reaction mixture from the low pressure and/or
low temperature stage is much less than in the past.
Furthermore, much less 2-methyl-1,4-butanediol is produced
concurrently in this finishing stage in the process of this
invention. The desired butanediol product is then obtained in
high yield by distillation.
The invention will now be illustrated with reference
to the following specific examples, which are to be considered
as illustrative, of, but not limiting the invention herein.
EXAMP1E 1
Adsorption of Molybdenum Compound on Raney Nickel
.
To 10.0 g aliquots of Raney nickel solids in 40 ml.
of water were added various proportions of molybdenum in the
form of ammonium mol~bdate. The suspensions were stirred at
FDI Ll3/1114/1114/A llZ~961
room temperature and, at intervals, filtered and the filtrates
analyzed for molybdenum content. The following Table I gives
the extent of adsorption of molybdenum as a function of time
of stirring.
TABLE I
Ratio of Wt. of Mo Added to Wt~ of
Raney Solids Present
0.04 0.08 0.12
% of Mo Char~e Adsorbed on Catalyst
Time of Stirring
.
lO min. 83 75 73
30 min. 85 77 74
l.0 hr. 87 79 75
4.0 hrs. 89 81 76
24.0 hrs. 93 91 87
EXAMPLE 2
Preparation of Catalyst of Invention
To 20.0 g. of commercial Raney nickel containing
about 50% nickel particles as ar. aqueous slurry was added
solid ammonium molybdateJ(NH4)6 Mo7O24,4H20, and the mixture
was stirred for an hour. The catalyst thus prepared then was
added directly to the butynediol solution for use in the
hydrogenation process.
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FD~ 13 /1114/1114/A 1122961
Catalysts were prepared in this manner corresponding
to about 2, 3, 4, 5, 6 and 8 parts by weight of molybdenum
added per 100 parts of Raney nickel solids for hydrogenation
of butynediol.
Examples 3-9 below illustrate hydrogenations using
the catalysts of the invention as well as other standard and
related catalysts, presented for purposes of comparison. The
results of these examples are given in Table II which follows
the examples. The data presented therein for the low
pressure, low temperature stage is the carbonyl number of the
product, which is a conventional measure of aldehyde and
acetal content, and the amount of residual formaldehyde. For
the finishing stage, the data presented is the carbonyl number
of the product and the amount of MBlD in the product.
EXAMPLE 3
Hydrogenation with Raney Nickel
A. Low Pressure, Low Temperature Stage (First Stage)
500 g. of aqueous 35% butynediol solution, containing
0.40% formaldehyde, and a catalyst comprising 20 g. of
commercial 50% Raney nickel slurry was hydrogenated under
agitation at 60C. and 300 psig. of hydrogen. ~fter 6 hours,
the catalyst was allowed to settle and the supernatant product
was withdrawn. Thereafter, another 500 ml. of 35% butynediol
solution was added and the hydrogenation procedure was
repeated. Four successive hydrogenations were run with the
same catalyst. The results are given for the fourth run in the
series.
FD~- 13/1114/1114/A llZZ961
B. High Pressure, High Temperature Stage (Finishing 5tage)
The product of the low pressure stage was subjected
to finishing hydrogenation over a 15% nickel-7.8% copper-0.5
manganese catalyst on alumina at 2500 psig, and 150C. for
7.5 hours. The reaction product was then totally distilled,
and, after removing water, the organics were collected up to a
pot temperature of 180C. at 1 Torr.
EXAMPLE 4
Raney Nickel -Mo Alloy
The hydrogenation process of Example 3 was repeated
using an alloy catalyst containing 3% by weight molybdenum
prepared by alkali leaching of a nickel-molybdenum-aluminum
alloy.
EXAMPLE 5
Raney Ni + Mo Compound Adsorbed
The hydrogenation process of Example 3 was repeated
using the catalysts of the invention prepared according to
Example 2.
EXAMPLE 6
Raney Nickel Cr Alloy + Mo Compound Adsorbed
The hydrogenation process of Example 3 was repeated
using a catalyst prepared according to ~xample 2 from a
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FDI 113 /1114/1114/A
~12~9~1
commercial Raney nickel-chromium alloy containing 3% by weight
chromium in the alloy. Four parts of molybdenum were added
per 100 parts of Raney nickel solids.
EXAMPLE 7
._
Raney Nickel - Mo Alloy + Mo Compound Adsorbed
The hydrogenation process of Example 2 was repeated
using a commercial Raney nickel - molybdenum alloy containing
3% by weight molybdenum which was treated as in Example 2.
Four parts of molybdenum were added per 100 parts of the alloy
solids.
EXAMPLE 8
Raney Nickel + Mo and Cu Compounds Adsorbed
A catalyst comprising about 4 parts molybdenum
compound adsorbed per 100 parts of Raney nickel solids was
prepared and added to butanediol solution as in Example 3.
Then an additional 4 parts of copper, as copper acetate, was
dissolved in the butynediol solution, and the hydrogenation
process of Example 3 was repeated.
EXAMPLE 9
Raney Nickel + Cu Compound Adsorbed
_
The hydrogenation process of Example 3 was repeated
using a Raney nickel catalyst having about 6 parts of copper
adsorbed per 100 parts of Raney nickel solids, as in U. S.
2,953,605.
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FDN-1113 ' 14/1114/A
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A feature of the process of the invention is its
ability to effectively reduce carbonyl groups in organic
compounds, sometimes even selectively in the presence of
carbon-to-carbon unsaturated groups. For example, furfural
is reduced substantially to furfuryl alcohol in the process
of the invention. In contrast, a similar process, using
Raney nickel itself, or Raney nickel prepared from a
molybdenum-containing alloy, does not hydrogenate carbonyl
groups as efficiently, and forms considerable amounts of
tetrahydrofurfuryl alcohol by-product during the reduction
of furfural.
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~DN- 13/1114/1114/A l:lZ;~961
EXAMPLE 10
Hydrogenation of Furfural
Three identical hydrogenations were run using (A)
unmodified Raney nickel (B) Raney Nickel containing 3%
molybdenum alloyed as in the prior art, and (C) Raney
nickel containing about 4 parts by weight molybdenum
adsorbed per 100 parts of Raney nickel solids according to
this invention.
In each hydrogenation, 175 g of furfural in 325
g. aqueous isopropyl alcohol was catalyzed with 10.0 g of
the catalyst. After hydrogenation at 60C. and 300 psig
for 6 hours, the following results were obtained.
TABLE II
Catalyst Used
(A) (B) (C)
Components of Reaction Product % of Component
Furfuryl Alcohol 31.0 70.0 98.0
Tetrahydrofurfuryl Alcohol 51.9 25.8 1.6
Tetrahydrofurfural 7.4 0.9 0.0
Furfural 8.6 2.2 0.1
Others 1.1 1.1 0.3
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EXAMPLE 11
Hydrogenation of Formaldehyde
_ _
Two identical hydrogenations were run using (A)
unmodified Raney nickel and (B) Raney nickel containing
5about 4 parts of molybdenum adsorbed per 100 parts of Raney
nickel solids.
In each hydrogenation 7.25 g. of formaldehyde in
493 ml. of water was cataly~ed with 10.0 g. of the
catalyst. After hydrogenation at 60C and 3000 psig for 6
10hours, the following results were obtained.
TABLE III
Carbonyl
15 . No. % Formaldehyde
Initial Feed Solution 27.1 1.45
Catalyst of Hydrogenation
Unmodified Raney nickel (A) 7.0 0.36
Molybdenum adsorbed on Raney
nickel (B) 0.5 0.01
FD~- 13/1114/1114/A li2~96~
In summary, the process of the invention using the
novel catalyst provides improved catalytic hydrogenation of
butynediol to give high quality butanediol. The catalyst
rapidly reduces carbonyl groups so that very little aldehyde
by-products are obtained. In contrast, the Raney nickel
catalysts of the prior art produce substantially increased
amounts of aldehydes, acetals and condensation products, and
thus the quality of the butanediol product is appreciably
poorer.
While the invention has been described with reference
to certain embodiments thereof, it will be understood that
changes and modifications may be made which are within the
skill of the art. Accordingly, it is intended to be bound by
the appended claims only, in which:
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