EP1051250A1

EP1051250A1 - Method for producing catalysts containing ruthenium and the use thereof for hydrogenation

Info

Publication number: EP1051250A1
Application number: EP99932416A
Authority: EP
Inventors: Stefan Antons; Lutz Frohn; Jörg-Dietrich Jentsch; Andreas Schulze Tilling; Erich Wolters
Original assignee: Bayer AG
Current assignee: Bayer AG
Priority date: 1998-01-31
Filing date: 1999-01-16
Publication date: 2000-11-15
Also published as: JP2002501817A; DE19803888A1; WO1999038613A1; AU3249499A; US6376414B1

Abstract

The invention relates to a method for obtaining advantageous catalysts, especially for hydrogenation. According to said method, a suspension of a ruthenium compound with a specific surface area of 50 to 300 m<2>/g is brought together with a solution of at least one metal compound. At least one of these metal compounds contains a different metal to ruthenium with an atomic number of 23 to 82. The mixture of the suspension and the solution is then treated with a reducing agent.

Description

Process for the preparation of ruthenium-containing catalysts and their use in hydrogenations

The present invention relates to a process for the preparation of particularly advantageous catalysts which contain ruthenium and at least one further metal with an atomic number in the range from 23 to 82 and the use of such catalysts in hydrogenations.

It is known that carboxylic acids can be catalytically reduced to alcohols using hydrogen. A summary of this can be found in Houben-Weyl, Methods of Organic Chemistry, 4th ed. Vol. Vl / lb, pages 103-107 (1984). If catalysts containing ruthenium are used (see p. 106), relatively high temperatures and very high pressures are required, e.g. Temperatures from 145 to 190 ° C and pressures from 700 to 950 bar.

J. Org. Chem. 24, 1847 (1959) describes a method for hydrogenating carboxylic acids in which rhenium oxide is used as a catalyst. However, long reaction times and high pressures are required. In addition, the yield and the selectivity are unsatisfactory.

For various hydrogenations, catalysts are also known which, in addition to ruthenium, contain other metals, e.g. Contain rhenium. Such multi-metallic catalysts can be in Raney form, in sponge form or as supported catalysts. For example, EP-A 724 908 describes Raney ruthenium catalysts which are modified by further metals and can be used for various hydrogenations. However, they require high catalyst weights and long reaction times. Raney ruthenium is produced by leaching the aluminum from a ruthenium / aluminum alloy with sodium hydroxide solution. As a result, the Raney ruthenium

Contains catalyst residues of aluminum as well as aluminum oxides and sodium hydroxide solution. - 2 -

This has a negative impact on catalyst performance. In addition, the handling of such catalysts is particularly complex since they are pyrophoric.

DE-A 195 10 438 describes a process for the preparation of 1,4-butanediol and tetrahydrofuran from furan. Ruthenium / rhenium

Sponge can be used. This can be obtained by reducing an aqueous Re2θ ₇ / RuCl3 solution. Such catalysts have unsatisfactory activities and selectivities.

WO 96/27436 describes ruthenium and rhenium-containing catalysts which are applied to a support material consisting of coal. A disadvantage of these catalysts is that they require temperatures and pressures in the case of hydrogenations at which racemizations occur to a considerable extent when optically active starting materials are used.

The production of high purity ruthenium oxide with a high specific surface area is described in DE-A 2 132 547. However, this monometallic catalyst shows only low activities in the hydrogenation of carboxylic acids. If optically active starting materials are used, racemizations also occur to a considerable extent.

A process has now been found for the preparation of catalysts which contain ruthenium and at least one further metal with an atomic number in the range from 23 to 82, which is characterized in that a slurry of a ruthenium compound which has a specific surface area in the range from 50 to 300 m ² / g, brings together with a solution of at least one metal compound, at least one of these metal compounds containing a metal other than ruthenium with an atomic number in the range 23 to 82 and treating the mixture of slurry and solution with a reducing agent. - 3 -

According to the present invention, e.g. Manufacture bimetallic ruthenium / metal X catalysts and trimetallic ruthenium / metal X / metal Y catalysts. Catalysts made according to the invention contain ruthenium and e.g. the metals X and optionally Y in elemental form and can e.g. present as a colloid or in the form of intermetallic compounds. examples for

Metals X and Y are rhenium, osmium, iron, cobalt, rhodium, palladium, platinum, copper, zinc, silver, tin, germanium, gallium, lead and tin. According to the invention, catalysts are preferably prepared which, in addition to ruthenium, contain one of the metals mentioned or, in addition to ruthenium, combinations of rhenium with copper, silver or tin. Ruthenium / rhenium are particularly preferred

Catalysts made.

The catalysts can contain the individual metal components in any ratio. Catalysts are preferred in which the individual metals are present in the same atomic ratios or in excess of ruthenium. at

Ruthenium / metal X catalysts are e.g. an atomic ratio Ru / X of 1/1 to 10/1, in particular of 1/1 to 5/1 is preferred.

Various slurry agents can be used to prepare the slurry of a ruthenium compound. These are preferably

Water. Suitable ruthenium compounds are in particular those which are simple, e.g. with hydrogen, reduced to metal. The ruthenium compounds can have various levels of oxidation, e.g. +3, +4 or +8. Ruthenium oxides and ruthenium oxide hydrates in which the ruthenium is present in the oxidation state +4 are preferred. Aqueous slurries

Containing ruthenium oxide or ruthenium oxide hydrate of the required specific surface area are commercially available or can be prepared in a known manner, for example by dissolving a water-soluble ruthenium compound, for example ruthenium trichloride, in water, making the solution alkaline and adding Add oxidant. A ruthenium (IV) oxide hydrate with a suitable specific surface then precipitates. By decanting, adding water and acid , 4th

and filtration, an aqueous slurry of ruthenium (IV) oxide or oxide hydrate can then be obtained which can be used directly for the preparation of catalysts according to the invention.

Slurries of ruthenium compounds which have a specific surface area in the range from 50 to 300 m ² / g and are suitable for the preparation of catalysts according to the invention are slurries which, calculated as metal, for example 0.01 to 20% by weight of ruthenium contain. These slurries preferably contain 0.1 to 4% by weight of ruthenium. Preferred slurries contain ruthenium compounds with a specific surface area

100 to 250 m / g.

The solution, which contains at least one metal compound in which at least one metal other than ruthenium with an atomic number in the range 23 to 82 is contained, can contain, for example, solvents which are miscible with the slurry for the ruthenium compound are. If the slurry medium for the ruthenium compound such as water, it may be ₄ alkyl alcohols act with the solvent for the other (s) metal compound (s), for example, water or C _j -C. Preferably the slurry and solvent is water. Metal compounds containing at least one other than ruthenium

Containing metal with an atomic number in the range 23 to 82 can be, for example, compounds of the metals which are soluble in the respective solvent and which are given above as examples of metals X and Y. Aqueous solutions of rhenium compounds are preferably used, in particular aqueous solutions of rhenium heptoxide (Re ₂ O ₇ ), which are also used as perrhenium acid (HReθ ₄ or Re ₂ O ₇ x

2 H ₂ O).

The solution, which contains at least one metal compound in which at least one metal other than ruthenium with an atomic number in the range 23 to 82 is contained, can, calculated as metal, for example 0.01 to 60% by weight of the metal compound (s) included. This content is preferably 0.1 to 5% by weight. - 5 -

One can also proceed in such a way that the solution which contains at least one metal compound in which at least one metal other than ruthenium with an atomic number in the range 23 to 82 is contained, is generated in situ. For example, the slurry of a ruthenium compound with the required specific surface and optionally additional solvent can be introduced and the metal compound (s) added in solid form. The formation of the solution of the metal compound (s) and their bringing together with the slurry of the ruthenium compound then take place simultaneously.

The treatment of the mixture of slurry and solution with a reducing agent can in principle be carried out with all reducing agents which are able to reduce the ruthenium compound and the other metal compound (s). In many cases, especially because then there are practically no disruptive by-products, treatment with hydrogen at temperatures in the

Range 50 to 200 ° C and pressures in the range 5 to 200 bar have been found to be advantageous.

Since the catalysts prepared according to the invention can preferably be used for hydrogenations, the reduction described above with hydrogen can also be carried out in the reaction vessel for the hydrogenation, preferably immediately before

Hydrogenation can be carried out yourself.

One can also proceed by reducing the slurry of a ruthenium compound before contacting it with the solution of one or more compounds of other metals and reducing it again after bringing the slurry and the solution together.

Catalysts produced according to the invention have an intimate contact of the metals contained therein and specific surfaces of, for example, 50 to 150 m ² / g. The individual catalyst particles generally contain all metals, the compounds of which were used in the manufacture of the catalyst. There are - 6 -

there are practically no particles that contain only one metal, for example only ruthenium. This has been shown by microanalytical and electron microscopic investigations.

Catalysts produced according to the invention have a high activity. This is surprisingly significantly higher than in the case of catalysts of identical composition which were prepared by reducing a solution which contained a ruthenium compound and at least one metal compound of a metal other than ruthenium with an atomic number in the range from 23 to 82 (see Example 5).

Catalysts produced according to the invention can be used in particular for hydrogenations. Important uses are e.g. the production of optionally optically active alcohols from optionally optically active carboxylic acids, carboxylic esters and carboxamides; the production of optionally optically active amino alcohols from optionally optically active amino acids, esters and amides, the production of alcohols from carboxylic acids, in particular saturated diols from saturated or unsaturated dicarboxylic acids, dicarboxylic acid esters and dicarboxylic acid amides and the production of optionally optically active alcohols optionally optically active hydroxycarboxylic acids, hydroxycarboxylic acid esters and hydroxycarboxylic acid amides. Individual examples are the preparation of L-l, 2,4-butanetriol from L-malic acid, from

L-alaninol from L-alanine, from n-butanol and 1,4-butanediol from maleic acid and from 1,6-hexanediol from adipic acid. Hydrogenations with catalysts prepared according to the invention can be carried out, for example, at 0 to 120 ° C. and 5 to 300 bar.

Catalysts produced according to the invention can optionally be treated with sulfur compounds, e.g. Thioethers.

Catalysts produced according to the invention are free from support materials, aluminum, aluminum oxides and alkalis. - 7 -

Catalysts produced according to the invention are distinguished by the fact that they can be used to carry out hydrogenations under milder conditions, in higher yields while largely maintaining optical activities and / or without appreciable impairment of functional groups which are otherwise present. In addition, not particularly large amounts of catalysts are required and the reaction times are generally significantly shorter than in the case of ruthenium-containing catalysts of the prior art.

The present invention also relates to ruthenium-containing catalysts free of support materials, which can be obtained by using a slurry of a

Ruthenium compound, which has a specific surface area in the range 50 to 300 m ² / g, with a solution of at least one metal compound, wherein at least one of these metal compounds contains a metal other than ruthenium with an atomic number in the range from 23 to 82 and the mixture of slurry and solution treated with a reducing agent.

- 8th -

Examples

example 1

a) Preparation of a ruthenium oxide hydrate slurry

103 g of ruthenium trichloride were dissolved in 7.75 l of water and heated to 50 ° C. A 20% by weight aqueous sodium hydroxide solution was added dropwise while stirring at 50 ° C. until a pH of 8 was reached. Then 1.125 l of a 2% by weight aqueous hydrogen peroxide solution were added with stirring and

Stirred at 50 ° C for 30 min. The precipitate was allowed to settle, decanted once, made up to 10 liters with water and decanted again. The mixture was then made up to 3.3 l, stirred at 80 ° C. for 6 hours and 4.5 ml of acetic acid were added. After cooling, the precipitate present was filtered off. 412 g of ruthenium oxide hydrate in the form of a pasty sludge with a ruthenium

Obtained content of 12 wt .-%. The specific surface area of the precipitate was determined to be 210 m ² / g after drying in vacuo at 100 ° C. using the BET method.

b) adding rhenium and reduction

In a 0.7 l stainless steel autoclave, 99.3 g of water-moist ruthenium oxide (obtained according to a)) and 6.3 g of rhenium heptoxide (containing 76.9% by weight of rhenium) were introduced. It was flushed twice with nitrogen and twice with hydrogen, pressurized with 100 bar of hydrogen and heated to 120 ° C. with stirring (800 rpm). After reaching this temperature, the hydrogen pressure was increased to 150 bar and the catalyst was reduced at 120 ° C. for one hour. The pressure was then released and the catalyst was filtered off. Neither ruthenium nor rhenium was detectable in the filtrate. The dried catalyst contained less than 1% by weight sodium and less than 1% by weight chlorine. The mean size of the ruthenium-rhenium particles determined by laser light scattering was 16 μm. - 9 -

The specific surface area of the catalyst was determined to be 70 m ² / g after drying in vacuo at 100 ° C. using the BET method.

Example 2

The procedure was as in Example 1, but the temperature was kept at 60 ° C. during the reduction. The filtrate also contained neither ruthenium nor rhenium.

Example 3

The procedure was as in Example 1, but the reduction was carried out at a hydrogen pressure of 10 bar. The filtrate contained no ruthenium, but in an amount of 200 mg / 1 rhenium, which corresponds to 3.5% by weight of the rhenium used.

Example 4

The procedure was as in Example 1, but 240 mg of iron in the form of iron oxalate were added instead of the rhenium heptoxide.

Example 5

(For comparison - without separation of ruthenium oxide hydrate)

9.83 g of ruthenium trichloride and 6.3 g of rhenium heptoxide (containing 76.9% by weight of rhenium) were placed in 100 ml of water in a 0.7 l stainless steel autoclave. It was flushed twice with nitrogen and twice with hydrogen, 100 bar of hydrogen were injected and the mixture was heated to 120 ° C. with stirring (800 rpm). After reaching this temperature, the hydrogen pressure was increased to 150 bar and the

Reduced catalyst at 120 ° C for one hour. Then was relaxed and - 10 -

the catalyst is filtered off. The filtrate contained 0.074 mg / 1 ruthenium and 0.39 mg / 1 rhenium.

Example 6

Hydrogenation of L-malic acid with the catalyst obtained according to Example 1.

The catalyst obtained in Example 1 was placed in a 0.7 1 stainless steel autoclave, made up with 100 ml of water and heated to 60 ° C. The mixture was then flushed twice with nitrogen and twice with hydrogen and 278 g of one

18.9% by weight aqueous solution of L-malic acid is sucked in. Then was stirred at 60 ° C and 200 bar hydrogen pressure until the end of the hydrogen uptake (800 rpm). After cooling to room temperature, the catalyst was filtered off, the product solution was neutralized with sodium hydroxide solution and the water was distilled off from the crude solution obtained. 42.0 g of a colorless viscous remained

Liquid distilled at a pressure of 1 mbar. After a preliminary run, which consisted of butanediols, 33.9 g of 97.9% by weight L-l, 2,4-butanetriol were obtained (bp. 133 ° C./1 mbar; ee = 98.8%). This corresponds to a yield of 79.8%, based on malic acid used.

Examples 7 to 10

The procedure was as in Example 6, but the catalysts obtained in Examples 2, 3, 4 and 5 were used. The results obtained are shown in Table 1. 11 -

Table 1

Catalyst from yield ee value

Example 7 Example 2 78.9% 98.8%

Example 8 Example 3 84.8% 97.8%

Example 9 Example 4 62.9% 94.3%

Example 10 Example 5 6.6% not determined (comparative example)

Examples 11 to 14

(Comparative examples - of rhenium-free catalyst)

A catalyst was prepared according to Example 5, but no rhenium heptoxide was used. This catalyst was used analogously to Example 6 at various temperatures in the hydrogenation of L-malic acid. The results obtained are shown in Table 2.

Table 2

Temperature yield *) ee value

Example 11 60 ° C no conversion -

Example 12 80 ° C 19.9% 90.9%

Example 13 100 ° C 68.2% 78.4%

Example 14 120 ° C 45.2% 0.1%

^ an Ll ^ -Butantriol - 12 -

Example 15

Hydrogenation of L-alanine

A suspension of 6 g of ruthenium rhenium catalyst obtained according to Example 1 was placed together with 100 ml of water in a 0.7 1 stainless steel autoclave. A solution of 60.0 g of L-alanine and 32.9 g of sulfuric acid in 370 g of water was added. After flushing with nitrogen, 100 bar of hydrogen were injected. The temperature was raised to 60 ° C. within 30 minutes and the hydrogen pressure was raised to 200 bar. After a reaction time of 7 h, the uptake of hydrogen had ended. It was cooled to room temperature, let down, the catalyst was separated off from the reaction mixture by filtration and the water was distilled off from the filtrate. The residue remaining after the water had been distilled off was adjusted to a pH of 11.4 using 59.7 g of 45% strength by weight aqueous sodium hydroxide solution and fractionally distilled at 50 mbar. 35.7 g of pure L-

Obtained alaninol (bp: 94 ° C / 50 mbar); ee> than 99.9%. This corresponds to a yield of 71% of theory. The ee value was determined by gas chromatography.

Example 16

(Comparative example - of rhenium-free catalyst)

A catalyst was prepared according to Example 1, but no rhenium was added. With this catalyst, L-alanine was reduced as described in Example 15. The hydrogenation time increased to 35 h. The yield and the ee value of the L-alaninol obtained corresponded to Example 15. 13 -

Example 17

(Hydrogenation of maleic acid)

9.6 g of the water-containing catalyst, obtained according to Example 1, were placed in 200 ml of water in a 0.7 1 stainless steel autoclave. A solution of 52.5 g of maleic acid in 125 ml of water was added. After flushing with nitrogen, 100 bar of hydrogen were injected. The temperature was raised to 100 ° C. and the hydrogen pressure to 200 bar. After a reaction time of 3.7 h, the hydrogen uptake had ended. It was cooled to room temperature, let down and the catalyst was separated from the reaction mixture by filtration. The filtrate was examined by gas chromatography, the proportions of reaction products shown in Table 3 being found, without taking water into account.

Table 3

Component content (GC%)

Tetrahydrofuran 4% n-propanol 1% n-butanol 22%

1,4-butanediol 64%

Unknown substances 8%

Example 18

Hydrogenation of adipic acid

a) Catalyst activation

In a 0.7 l stainless steel autoclave, 14 g of ruthenium oxide hydrate (containing 7.61% by weight of ruthenium) and 1.4 g of rhenium 14 -

heptoxid (containing 76.9 wt .-% rhenium) presented. It was flushed twice with nitrogen and twice with hydrogen and heated to 120 ° C. with stirring (800 rpm). After reaching this temperature, the hydrogen pressure was increased to 150 bar and the catalyst was reduced at 120 ° C. for one hour.

b) hydrogenation of adipic acid

The autoclave was cooled, let down, and 70 g of adipic acid were added. Then it was flushed with nitrogen and hydrogen and pressurized at 100 ° C. and 200 bar hydrogen for 8 hours. The mixture was then cooled to room temperature, depressurized and the catalyst was separated from the reaction mixture by filtration. The filtrate was examined by gas chromatography. This gave the proportions of reaction products shown in Table 4 - without taking water into account.

Table 4

Component content (GC%) n-pentanol 1.2% n-hexanol 7.12%

1,6-hexanediol 85.0%

6-hydroxycaproic acid 6.6%

Adipic acid 0%

Claims

- 15 patent claims

1. Process for the preparation of catalysts which contain ruthenium and at least one further metal of an atomic number in the range from 23 to 82, characterized in that a slurry of a ruthenium compound which has a specific surface area in the range from 50 to 300 m ² / g, brings together with a solution at least one metal compound, at least one of these metal compounds containing a metal other than ruthenium with an atomic number in the range from 23 to 82 and treating the mixture of slurry and solution with a reducing agent.

2. The method according to claim 1, characterized in that one produces bimetallic ruthenium / metal X catalysts or trimetallic ruthenium / metal X7 metal Y catalysts, where X and Y rhenium, osmium, iron,

Cobalt, rhodium, palladium, platinum, copper, zinc, silver, tin, germanium gallium, lead and / or tin mean.

3. Process according to claims 1 and 2, characterized in that ruthenium / rhenium catalysts are produced.

4. The method according to claims 1 to 3, characterized in that the slurry contains 0.01 to 20 wt .-% ruthenium, calculated as the metal.

5. The method according to claims 1 to 4, characterized in that the solution containing at least one metal compound in which at least one metal other than ruthenium is contained with an atomic number in the range 23 to 82, calculated as metal, 0.01 to 60 % By weight of the metal compound (s) contains. - 16 -

6. Process according to Claims 1 to 5, characterized in that the treatment with a reducing agent is carried out with hydrogen at temperatures in the range from 50 to 200 ° C and pressures in the range from 5 to 200 bar.

7. Ruthenium-containing catalysts free of support materials, characterized in that they are obtainable by bringing together a slurry of a ruthenium compound having a specific surface area in the range from 50 to 300 m ² / g with a solution of at least one metal compound, at least one of these metal compounds contains a metal other than ruthenium with an atomic number in the range from 23 to 82 and the mixture of slurry and solution is treated with a reducing agent.

8. Use of ruthenium-containing catalysts according to claim 7 or obtained according to claims 1 to 6 for hydrogenations.

9. Use according to claim 8 for the preparation of diols from saturated or unsaturated dicarboxylic acids, dicarboxylic acid esters and / or dicarboxylic acid amides.

10. Use according to claim 8 for the production of amino alcohols from amino acids, esters and / or amides.

11. Use according to claim 8 for the production of alcohols from hydroxycarboxylic acids, hydroxycarboxylic acid esters and / or hydroxycarboxylic acid amides.