GB2104794A

GB2104794A - Raney nickel catalyst

Info

Publication number: GB2104794A
Application number: GB08219909A
Authority: GB
Inventors: Eugene Victor Hort; Thomas Waldo R De
Original assignee: GAF Corp
Current assignee: GAF Corp
Priority date: 1978-07-12
Filing date: 1982-07-09
Publication date: 1983-03-16
Also published as: DE2926641A1; FR2430926A1; DE2926641C2; GB2025251A; GB2025251B; CA1122961A; NL7905449A; FR2430926B1; IT1193477B; GB2104794B; DE2953893A1; IT7923108A0

Abstract

A Raney nickel catalyst comprises Raney nickel solids with a molybdenum compound adsorbed thereon in an amount of 2 to 8 parts by weight Mo to 100 parts Ni. The catalyst is useful for reducing butanediol to butanediol and reducing carbonyl compounds, e.g. furfuraldehyde and formaldehyde.

Description

1 GB 2 104 794 A 1

SPECIFICATION

Raney nickel catalyst and catalytic hydrogenation of organic compounds therewith This invention relates to a novel Raney nickel catalyst. It can be used for the reduction of organic compounds, notably for reducing carbonyl compounds and for preparing butanediol from butynediol, when, more particularly, it may be employed in the first stage of a two stage process for obtaining butanediol of high quality. This process is claimed by our co-pending U.K. application 79.13849, published under no. 202525 1 A.

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. 3,920,7 59.

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. 3,950,44 1. This 15 reaction proceeds in two reduction steps. First, butynediol is reduced to butenediol, and then butenediol is hydrogenated to butanediol. Some of the butynediol starting material, however, is reduced concurrently to form an isomer of butenediol, which is 4- hydroxybutyraidehyde (HBA). The HBA by product hydrogenates more slowly than butenediol. Furthermore, HBA 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 25 stage conditions with any unremoved formaldehyde present in the butynediol solution to form condensation products, which, upon hydrogenation, give 2-methy]-1,4- butanediol (MB,D). The M13,1) 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 is a well known hydrogenation catalyst., 30 which was described originally in U.S. Patent 1,638,190 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 leaching out the aluminum with alkali to expose the nickel as porous, finely- divided, solid particles, in which state nickel is an effective hydrogenation catalyst.

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 U.S. 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 and unsuitable hydrogenation catalysts in comparison with the improved Raney nickel catalysts of this 40 invention for the low pressure reduction of butynediol to butanediol.

According to one aspect of this invention there is provided an improved Raney nickel catalyst comprising Raney nickel solids having adsorbed thereon a molybdenum compound in an amount of about 2 to 8 parts by weight molybdenum per 100 parts of the Raney nickel solids.

Optimally, there are 4 parts by weight of molybdenum per 100 parts by weight of Raney nickel solids. 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.

In a second aspect the invention provides a method of making the catalyst which consists of mixing a liquid suspension of Raney nickel with the molybdenum compound, added as a solid, dispersion of solution thereof.

Preparation of the catalyst may start with commercially 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 molbydenum 55 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.

Generally, 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 10 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.

2 GB 2 104 794 A 2 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 such metals also is adsorbed on the nickel, or they may be originally present in alloy form as part of the Raney nickel.

As mentioned above, the catalyst may be used in a catalytic hydrogenation process for the 5 preparation of butanediol from butynediol. 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.

The aqueous suspension resulting from the above described preparation may be used as such as 10 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.

In a typical implementation of the process, the reaction mixture for hydrogenation is prepared with a crude aqueous butynediol solution containing about 10-60% by weight butynediol, preferably about 15 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 4-10, preferably about 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. 25 The reaction mixture is agitated at a temperature of about 15' - 1 001C., preferably at about 500 - 701C., and optimally, at about 600C. 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 30 containing only small amounts of aldehydes, acetais, 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- 35 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 40 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 1 601C. A stream of hydrogen is simultaneously charged under pressure to the reactor. The reactor is filled with a fixed bed of suitable catalyst, which is different than that used in the low-pressure step. A typical high 45 pressure catalyst, as described in said patent, comprised 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.

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 the 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.

EXAMPLE 1

Adsorption of Molybdenum Compound on Raney Nickel To 10.0 g aliquots of Raney nickel solids in 40 mi. of water were added various proportions of 60 molybdenum in the form of ammonium molybdate. The suspensions were stirred at room temperature and, at intervals, filtered and the filtrates analyzed for molybdenum content. The following Table 1 gives the extent of adsorption of molybdenum as a function of time of stirring.

3 GB 2 104 794 A 3 TABLE 1

0.04 Time of Stirring Ratio of Wt. of Mo Added to Wt. of Raney Solids Present 0.08 % of Mo Charge Adsorbed on Catalyst 0.12 min. 83 75 73 min. 85 77 74 1.0 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 an aqueous slurry was added solid ammonium molybdate, (NH4) 6 MoA,4 H20, and the mixture was stirred for an hour. 5 The catalyst thus prepared then was added directly to the butynediol solution for use in the hydrogenation process.

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 10 other standard and related catalysts, presented for purposes of comparison. The results of these examples are given in Table 11 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 M1311) in the product.15 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 600C. and 300 psig. of hydrogen. After 6 hours, the catalyst was allowed to settle and the supernatant product. 20 was withdrawn. Thereafter, another 500 mi. of 35% Sutynediol 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.

B. High Pressure, High Temperature Stage (Finishing Stage) The product of the low pressure stage was subjected to finishing hydrogenation over a 15% 25 nickel-7.8% copper-0.5% manganese catalyst on alumina at 2500 psig, and 1501C. 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 1 801C. 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 Nickel + Mo Compound Adsorbed The hydrogenation process of Example 3 was repeated using the catalysts of the invention 35 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 Example 2 from a commercial Raney nickel-chromium alloy containing 3% by weight chromium in the 40 alloy. Four parts of molybdenum were added per 100 parts of Raney nickel solids.

4 GB 2 104 794 A 4 EXAM P LE 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 the butynediol solution, and the hydrogenation process of 10 Example 3 was repeated.

EXAMPLE 9 Raney Nickel + Cu Compound Adsorbed The hydrogenation process of Eample 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.

TABLE 11

LOW PRESSURE HIGH PRESSURE, LOWTEMPERATUE HIGH TEMPERATURE STAGE STAGE Example Carbonyl Formaldehyde Carbonyl MB1D No. No. (%) No. (%) 3 Ni 48 0.22 0.3 2.0 4 Ni-Mo 2.2 0.16 0.3 1.6 Ni+2Mo 9 0.10 0.3 0.9 Ni+3Mo 7 0.08 0.15 0.7 Ni+4Mo 5 0.09 0.1 0.6 Ni+5Mo 5 0.09 0.1 0.6 Ni+6Mo 6 0.10 0.15 0.6 Ni+8Mo 6 0.08 0.2 0.5 6 Ni-Cr+4Mo 4.5 0.10 0.1 0.6 7 Ni-Mo+4Mo 17 0.12 0.3 1.2 8 Ni+41Vio+4Cu 5 0.09 0.2 0.6 9 Ni+6Cu 37 0.16 0.3 2.0 The catalyst of this invention is effective to reduce carbonyl groups in organic compunds, sometimes even selectively in the presence of carbon-tocarbon 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. ' EXAMPLE 10

Hydrogenation of Furfural Three identical hydrogenations were run using (A) unmodified Raney nickel (B) Raney Nickel 25 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.

GB 2 104 794 A 5 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 6WC. and 300 psig for 6 hours, the following results were obtained.

TABLE 11

Catalyst Used (A) (B) (C) Components of Reaction Product % of Component Furfuryl Alcohol 31.0 70.0 98.0 Tetra hydrof urf uryl 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 EXAMPLE 11 Hydrogenation of Formaldehyde Two identical hydrogenations were run using (A) unmodified Raney nickel and (B) Raney nickel containing about 4 parts of molybdenum adsorbed per 100 parts of Raney nickel solids.

In each hydrogenation 7.25 g. of formaldehyde in 493 m]. of water was catalyzed with 10.0 g. of the catalyst. After hydrogenation at 601C and 3000 psig for 6 hours, the following results were 10 obtained.

TABLE Ill

Carbonyl % 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 In summary, 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 byproducts are obtained. In contrast, the Raney nickel catalysts of the prior art produce substantially 15 increased amounts of aldehydes, acetals and condensation products, and thus the quality of the butanediol product is appreciably poorer.

Claims

1. An improved Raney nickel catalyst comprising Raney nickel solids having adsorbed thereon a molybdenum compound in an amount of about 2 to 8 parts by weight molybdenum per 100 parts of the 20 Raney nickel solids.

2. A catalyst according to Claim 1 wherein said amount of molybdenum is about 4 parts by weight.

3. A catalyst according to claim 1 or claim 2 which includes at least one additional metal selected from the group consisting of copper, cobalt, tungsten, zirconium, platinum and palladium.

4. A catalyst according to Claim 3 wherein said metal is copper.

5. A catalyst according to any one of Claims 1 to 4 wherein said molybdenum compound is a molybdenum salt or oxide.

6. A catalyst according to any one of Claims 1 to 4 wherein said molybdenum compound is selected from an ammonium molybdate, an alkali molybdate and molybdenum trioxide.

6 GB 2 104 794 A 6

7. A method of making a catalyst according to any one of Claims 1 to 6 which consists in mixing a liquid suspension of Raney nickel with the molybdenum compound, added as a solid, dispersion or solution thereof.

8. A method according to Claim 7 wherein said liquid is water.

9. A catalyst made by the method of claim 7 or 8.

10. A method of effectively and rapidly reducing a carbonyl group present in an organic compound which comprises:

(a) forming a mixture of said compound and a Raney nickel catalyst according to any one of Claims 1 to 6 and 9 and (b) introducing hydrogen into said mixture thereby to reduce the carbonyl group of said compound.10

11. A process according to Claim 10 wherein said compound is formaldehyde.

12. A process according to Claim 10 wherein said compound is furfural.

13. A process according to any one of claims 10 to 12 wherein said carbonyl group is reduced to the corresponding hydroxy group.

14. A Raney nickel catalyst according to claim 1 substantially as any herein described with 15 reference to Examples 1 and 2 herein.

15. A process for the production of an organic compound, substantially as herein described with reference to either run C of Example 10 or run B of Example 11 herein.

Printed for Her Majesty's Stationery Office by the Courier Press, Leamington Spa, 1983. Published by the Patent Office, 26 Southampton Buildings, London, WC2A lAY, from which copies may be obtained.

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