GB2025251A

GB2025251A - Catalytic hydrogenation of organic compounds

Info

Publication number: GB2025251A
Application number: GB7913849A
Authority: GB
Original assignee: GAF Corp
Current assignee: GAF Corp
Priority date: 1978-07-12
Filing date: 1979-04-20
Publication date: 1980-01-23
Also published as: IT7923108A0; IT1193477B; NL7905449A; FR2430926A1; DE2926641C2; CA1122961A; GB2025251B; DE2926641A1; GB2104794A; GB2104794B; DE2953893A1; FR2430926B1

Abstract

Raney nickel with a molybdenum compound adsorbed on it at 0.5-15 parts by weight molybdenum per 100 parts of Raney nickel solids is used in catalytic hydrogenation processes for the reduction of organic compounds. It can be employed for preparing butanediol from butynediol, more particularly, the first stage of a two stage process for obtaining butanediol of high quality. It can also be used for the reduction of formaldehyde or furfural.

Description

SPECIFICATION Catalytic hydrogenation of organic compounds This invention relates to an improved catalytic hydrogenation process for the reduction of organic compounds, notably 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. The invention also relates to a novel Raney nickel catalyst for use in the process.

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, 2,950,3262,953,605; 3,449,445; 3,449,445; 3,479,411; 3,691,093; 3,759,845 and 3,950,441. The starting butynediol solution is obtained bya 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 to butanediol. Some of the butynediol starting material, however, is reduced concurrently to form an isomer of butenediol, which is 4'hydroxybutyraldehyde (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 stage conditions with any unremoved formaldehyde present in the butynediol solution to form condensation products, which, upon hydrogenation, give 2-methyl-1,4-butanediol (MB1D). The MB1D 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, 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 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, it is an object of the present invention to provide an improved catalytic hydrogenation process for the preparation of butanediol of high quality.

Another object of the invention is to provide a low pressure, low temp,erature catalytic hydrogenation stage for making butanediol from butynediol in which less aldehyde and acetal byproducts 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 it produces a higher quality of butanediol, i.e.

less aldehyde and acetal and condensation products thereof, and thereby increases the quality of butanediol obtained in the process.

Accordingly, in one aspect, the invention provides 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 (which is another aspect of the invention) 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 0.5-1 5 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 such metals also is adsorbed on the nickel, or they may be originaity 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, suitably about 0.5-1 5 parts by weight of molybdenum per 100 parts by weight of Raney nickel solids present is used as the catalyst 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 1060% by weight butynediol, preferably about 2550%, 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 91 0, 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 130% by weight of catalyst per weight of butynediol will be employed, with about 312% 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.

The reaction mixture is agitated at a temperature of about I 50-1000C., preferably at about 500--700C., and optimally, at about 600 C. 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 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 1 600 C. A stream of hydrogen is simultaneously charged under pressure to the reactor.The reactor is filled with a fixed bed of a suitable catalyst, which is different 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 10 minutes to 24 hours is suitable for this purpose, and about one hour generally is ampie to absorb the desired amount of the molybdenum compound onto the nickel. The resulting 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.

EXAMPLE 1 Adsorption of Motybdenum 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 molybdate. The suspensions were stirred at 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 Time of Stirring % of Mo Charge Adsorbed on Catalyst 10 min 83 75 73 30 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 Mo7024,4H20, 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.

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 MB1D 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 600 C.

and 300 psig. of hydrogen. After 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.

B. High Pressure, High Temperature Stage (Finishing Stage) The product of the low pressure stage was subjected to finishing hydrogenation over a 1 5% nickel7.8% copper-0.5% manganese catalyst on alumina at 2500 psig, and 1 500 C. for 7.5 hours.

The reaction product was then totally distilled, and, after removing water, the organics were collected u; to a pot temperature of 1800C. 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 CompoundAdsorbed The hydrogenation process of Example 3 was repeated using the catalysts of the invention prepared according to Example 2.

EXAMPLE 6 Raney Nickel-CrAlloy+Mo Compound A dsorbed .

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 alloy. Four parts of molybdenum were added per 100 parts of Raney nickel solids.

EXAMPLE 7 Raney Nickel-Mo Alloy+Mo CompoundAdsorbed 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 CompoundAdsorbed 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.

TABLE II A. LOW PRESSURE, LOW TEMPERATURE STAGE Ex.3 Ex.4 Ex.5 Ex.5 Ex.5 Ex.5 Ex.5 Ex.5 Ex.6 Ex.7 Ex.8 Ex.9 Ni Ni-Mo Ni+2Mo Ni+3Mo Ni+4Mo Ni+5Mo Ni+6Mo Ni+8Mo Ni-Cr+4Mo Ni-Mo+4Mo Ni+4Mo+4Cu Ni+6Cu Carbonyl No. 48 22 9 7 5 5 6 6 4.5 17 5 37 Formaldehyde (%) 0.22 0.16 0.10 0.08 0.09 0.09 0.10 0.08 0.10 0.12 0.09 0.16 B. HIGH PRESSURE, HIGH TEMPERATURE STAGE Carbonyl No. 0.3 0.3 0.3 0.15 0.1 0.1 0.15 0.2 0.1 0.3 0.2 0.3 MB1D (%) 2.0 1.6 0.9 0.7 0.6 0.6 0.6 0.5 0.6 1.2 0.6 2.0 A feature of the process of the invention is its ability to effectively reduce carbonyl groups in organic compounds, sometimes even selectively in the presedce 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 molybdenumcontaining aloy, 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 Furfurla 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, 175g of furfural in 325 g. aqueous isopropyl alcohol was catalyzed with 10.0 g of the catalyst. After hydrogenation at 60 C. and 300 psig for 6 hours, the following results were obtained.

TABLE I 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 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 ml. of water was catalyzed with 10.0 g. of the catalyst. After hydrogenation at 600C and 3000 psig for 6 hours, the following results were 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 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 amount 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:

Claims

1. A process for the catalytic reduction of an organic compound which comprises: a) forming a mixture of said compound and a Raney nickel catalyst comprising Raney nickel solids having adsorbed thereon a molybdenum compound in an amount of about 0.1-1 5 parts by weight molybdenum per 100 parts of the Raney nickel solids, and, b) introducing hydrogen into said mixture thereby to reduce the compound.

2. In a process for the catalytic hydrogenationof butynediol to butanediol, the improvement which comprises: hydrogenating an aqueous solution of about 1060% by weight butynediol with hydrogen at a pressure within the range of about 1 5-600 psig, at a temperature of about 15"--1000C and a pH of about 4--1 0, in the presence of a slurry of a catalyst comprising Raney nickel having a molybdenum compound adsorbed on the nickel in an amount of about 0.5-1 5 parts by weight of molybdenum per 100 parts by weight of Raney nickel solids.

3. A process according to Claim 2 wherein the butynediol solution is about 2550% by weight, the pressure is about 200-400 psig, the temperature is about 500--700C., the pH is about 5-8, and the amount of molybdenum is about 2-8 parts by weight.

4. A process according to Claim 2 wherein the butynediol solution is about 35%, the pressure is about 300 psig., the temperature is about 600 C., the pH is about 7, and the amount of molybdenum is about 4 parts by weight.

5. A process according to any one of Claims 2v4 wherein said catalyst is prepared by mixing a suspension of Raney nickel in water witch' a molybdenum compound added as a solid, dispersion or solution thereof.

6. A process according to any one of Claims 2-5 wherein said compound is a molybdenum salt or oxide.

7. A process according to any one of Claims 2-5 wherein said molybdenum compound is an ammonium or alkali molybdate or molybdenum trioxide.

8. A process according to any one of Claims 2-7 wherein said catalyst includes at least one additional metal selected from the group consisting of copper, cobalt, tungsten, zirconium, platinum and palladium.

9. A process according to Claim 8 in which said metal is copper.

1 0. A process according to any one of Claims 2-9 which includes the additional step of subjecting the reaction product of the hydrogenation to a finishing hydrogenation stage at a higher pressure and/or higher temperature.

11. 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 molybdenum per 100 parts of the Raney nickel solids.

12. A catalyst according to Claim 11 wherein said amount of molybdenum is about 2-8 parts by weight.

13. A catalyst according to Claim 11 wherein said amount of molybdenum is about 4.parts by weight.

14. A catalyst according to any one of Claims 11-13 which includes at least one additional metal selected from the group consisting of copper, cobalt, tungsten, zirconium, platinum and palladium.

1 5. A catalyst according to Claim 14 wherein said metal is copper.

1 6. A catalyst according to any one of Claims 11 to 1 5 in which said catalyst is prepared by mixing a liquid suspension of Raney nickel with molybdenum compound, added as a solid, dispersion or solution thereof.

17. A catalyst according to any one of Claims 11 to 16 wherein said molybdenum compound is added as a molybdenum salt or oxide.

1 8. A catalyst according to any one of Claims 11 to 1 5 wherein said molybdenum compound is selected from an ammonium molybdate, an alkali molybdate and molybdenum trioxide.

19. A catalyst according to Claim 1 6 wherein said liquid is water.

20. 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 comprising Raney nickel solids having adsorbed thereon a molybdenum compound in an amount of about 0.1-1 5 parts by weight molybdenum per 100 parts of the Raney nickel solids, and, b) introducing hydrogen into said mixture thereby to reduce the carbonyl group of said compound.

21. A process according to Claim 20 wherein said compound is formaldehyde.

22. A process according to Claim 20 wherein said compound is furfural.

23. A process according to any one of Claims 20-22 in which said catalyst includes at least one additional metal selected from the group consisting of copper, cobalt, tungsten, zirconium, platinum and palladium.

24. A process according to any one of Claims 20 to 23 in which said catalyst is present in an -amount of about 0.2-3Q% by weight of said compound.

25. A process according to any one of claims 20 to 24 in which said compound is present in a solvent.

26. A process according to any one of claims 20 to 25 wherein said reaction is run at a temperature range from about room temperature to about 1 2000.

27. A process according to claims 20 to 26 wherein said reaction is run at a pressure range from about atmospheric to 1000 psig.

28. A process according to any one of claims 20 to 27 wherein said carbonyl group is reduced to the corresponding hydroxy group.

29. A Raney nickel catalyst substantially as any herein described with reference to Examples 1 and 2 herein.

30. A process for the hydrogenation of butynediol substantially as any herein described with reference to Examples 5, 6, 7 or 8 herein.

31. 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.