DE1156074B - Process for the preparation of a catalyst for the hydrogenation of organic compounds - Google Patents

Description

Process for the preparation of a catalyst for the hydrogenation of organic compounds The invention relates to a method of preparation of a new catalyst for the catalytic hydrogenation of organic compounds.

The partial hydrogenation of 1,4-butynediol to 1,4-butenediol (in the following simply called butynediol or butenediol) in the presence of various catalysts is known and is z. B. in U.S. Patent 2319707. All so far However, the catalysts used were subject to significant restrictions the required hydrogenation conditions and the yields were not very high. So z. B. when using a nickel catalyst, part of the butynediol for reduced corresponding butanediol and a mixture of butynediol, butenediol and Butanediol obtained. Poisoned or deactivated catalysts have also been suggested; however, these provided only slow reaction rates and had a relatively high rate short shelf life.

There were also palladium catalysts used, the one stepwise Caused reduction that can be interrupted in the butenediol stage; but these Catalysts cause side reactions, such as. B. isomerization, where y-oxybutyraldehyde is formed, which significantly reduces the yields.

In addition, when using palladium catalysts for reduction relatively low temperatures for the formation of resinous and other by-products necessary. Maintaining these low temperatures will not work only the reaction rate is greatly reduced, but it also arise Difficulty in handling. Another disadvantage of the palladium catalysts and the other catalysts used heretofore is that they are easily poisoned will.

In another known process with hydrogenation catalysts from heavy metals of the first, second or eighth group of the periodic table is merely a purification of butenediol already produced by hydrogenation carried out by removing unwanted amounts of butynediol that are still present. The hydrogenation of butynediol to butenediol thus requires a two-stage process in this case Way of working. Catalysts as they are to be produced according to the invention, however, are not used in this known method.

The object of the present invention is to produce a new one and improved hydrogenation catalyst for the hydrogenation of organic compounds, when using it, the disadvantages listed above are eliminated.

The inventive method for producing a catalyst for the hydrogenation of organic compounds in the liquid state is now thereby characterized in that one metallic, optionally on an inert, solid Finely divided palladium contained in the carrier in the preferably 0.02 to 2.0 percent by weight Dispersed aqueous solution of a copper salt containing copper salt and the Copper salt contained in the dispersion by reduction with a non-metallic Reducing agent, preferably hydrogen or hydrazine as metallic copper precipitates on the palladium.

This catalyst can be used for the catalytic hydrogenation of aromatic or aliphatic nitro compounds to the corresponding amines, from ethylenic unsaturated compounds to the corresponding saturated compounds and from Ketones and aldehydes are used to the corresponding alcohols and is special for the catalytic, selective partial hydrogenation of acetylenically unsaturated compounds suitable for the corresponding ethylenically unsaturated compounds.

Particularly favorable results are achieved with this catalyst in Hydrogenation of butynediol too Butenediol achieved, especially when the butynediol is for reduction with about 1 equivalent of hydrogen at one temperature between room temperature and about 1000 C and a pressure of about 1 to 20 atmospheres is treated. It was found that those described above were copper treated Palladium catalysts for the gradual reduction of butynediol to butenediol are much more selective than palladium alone and that they also increase the yield prevent reducing side reactions.

The catalyst which can be prepared according to the invention remains much longer active, which is probably due to the fact that the formation of side reactions and the resulting poisoning is reduced. He can therefore for a larger number of hydrogenations can be used. The longer catalytic effectiveness The catalyst can presumably also increase the resistance to poisoning can be attributed. When using the catalyst according to the invention can with lower pressure and, in contrast to palladium catalysts per se, at relatively high temperatures are used, which increases the rate of reaction and control of the exothermic reaction is facilitated.

For the production of the copper-treated palladium catalysts according to the invention is first an aqueous dispersion of a copper compound with metallic palladium mixed. The "dispersion" mentioned here includes solutions and finely divided suspensions, such as B. aqueous suspensions of hydrated copper oxides. The copper connections and copper salts can be used in a monovalent or divalent form as far as they are can be reduced to copper.

The best results will be with aqueous solutions, preferably at low concentrations of about 0.02 to 2.0 percent by weight, though if necessary, higher concentrations can also be used. For example The following copper compounds can be used according to the invention: Salts stronger Acids such as copper sulfate, copper chloride and copper nitrate; Salts of weak acids, such as copper cyanide, copper formate, copper acetate and copper carbonate, as well as copper oxide. Aqueous solutions of the strong acid salts are preferred to the reduction made slightly alkaline, such as B. od by adding sodium hydroxide. Like., Whereby a dispersion of hydrated copper oxide is formed, which is then in the presence of metallic palladium is treated with a reducing agent. The watery ones Solutions of easily soluble copper salts of the weak acids require before the reduction no regulation of the pr value in the presence of metallic palladium. Copper carbonate and copper oxide are poorly soluble and should be used for the preparation of an aqueous one Dispersion with metallic palladium, preferably with a small amount of one weak acid, e.g. B. acetic acid, be dissolved in water.

That used in the preparation of the catalyst of the invention metallic palladium may be in the form of fine particles without a carrier. In interest the economy and the ease of handling and to achieve better However, it is preferred to use metallic palladium on one of the results known inert carrier, such as carbon, alumina or silica, is applied, to use. These pal- Charge catalysts can, for example Contain 1 to 20, preferably 2 to 10 percent by weight of metallic palladium.

The particles of metallic palladium can be in any Size distribution are available. A suitable supported palladium catalyst can, for. B. be made by using charcoal or other carrier with a saturated aqueous solution of palladium chloride, drained, dried and then Glowing or heated in a reducing atmosphere such as hydrogen.

There will now be such an amount of the liquid dispersion of the copper compound in the presence of the memetallic palladium, that for each part of palladium is reduced about 5 to 30 parts of copper are deposited. Higher proportions of copper are in generally undesirable, since this reduces the catalytic efficiency; In contrast, lower proportions do not induce the desired improvements in the catalytic properties Properties.

The reduction of such a dispersion in the presence of the metallic Palladium can be carried out by any of the known methods, preferably by treatment with hydrogen at temperatures between room temperature and about 1000 C and a pressure between about 1 to 20 atmospheres. Instead of hydrogen can also use other known non-metallic reducing agents, such as hydrazine or Hydroxylamine.

The resulting slurry containing the copper treated Contains palladium catalyst, can either be filtered to separate the catalyst or directly for the hydrogenation of butynediol or others mentioned above hydrogenatable organic substances are used in the liquid state.

The physical structure of the catalysts of the invention is not entirely clarified, since the formed copper-treated opaque black Particles under the microscope are very similar to the untreated palladium particles. It is therefore assumed that these are particles of metallic palladium, which are covered with a porous copper coating and / or in contact with Copper particles stand.

As already mentioned, the palladium does not only act as a catalyst for the hydrogenation of butynediol but also catalyzes the isomerization or other side reactions of butynediol. The copper deposited on the palladium appears to prevent such side reactions without affecting the hydrogenation. The butenediol produced in this way is relatively pure and, since it is less Form by-products, obtained in higher yields.

By eliminating the resinous by-products that normally form, which poison the surface of the catalyst, the catalyst retains its effectiveness longer at. At the same time, the reaction speed remains the same and will not, as is the case with the use of already poisoned catalysts for partial reduction of butynediol, reduced.

To illustrate the side reaction catalyzed by palladium The following tests were carried out on the reduction of butynediol. The palladium catalyst was stirred together with butynediol for 10 hours at 600 C, every hour for 1 minute hydrogen was added for a long time to maintain the effectiveness of the catalyst. It a product was obtained which by attempting to distill it separate, vigorously polymerized.

On the other hand, the same procedure became the one treated with copper If a palladium catalyst was used, the butynediol did not change and it could can be fully recovered.

Example 1 a) 5 g of Solo palladium and 95 ovo charcoal containing, commercial catalyst were 1 hour together with 100 g of a 50% aqueous Copper acetate solution shaken at 400 C under a hydrogen pressure of about 5 kg / cm2. The one produced in this way, the copper treated palladium catalyst containing slurry could be used directly for hydrogenations in the liquid state, or it would filtered to separate the catalyst.

The approaches compiled in the table below show the breadth of application and the effectiveness of a copper-treated palladium catalyst which had been prepared in accordance with the above information. The amount of catalyst used in batches 1, 2, 3, 4 and 6 corresponded to the batch above. In runs 2 and 3, a catalyst was used which had already been used once or twice in hydrogenations of the same type. b) The scope and effectiveness of this catalyst result from the following hydrogenation approaches: Water er Approach Mg Concentrate A solution used Catalyst Tem- hydrogen Hydrogenated H Approach V, amount of tration solution used Catalyst temperature over- hydrogenated 1 yield rigid g ° / o ° C kg / cm2 g ° / ° o C g 0/0 0 kg / cm 'g 0/0 0 1 674 38.3 1,4-butynediol water simple addition 40 5 1 f 233 88.4 6.8 sentence after a) 2,674 38.3 1,4-butynediol water once 40 5 o 234 88.7 7.0 back- e9 guided catalyst [after a)] | S; 3,674 38.3 1,4-butynediol water twice 40 5 rv 231 87.4 7.8 return- led 0 catalyst [after a) l 4 560 30 propargylic water simple an- 50 2.8 allyl alcohol 167 96 alcohol sentence according to a) 5 168 100 2-methyl- - 2 g 60 10.5 2-methyl- 160 91 102 (bp) 3-butynol- (2) butanol- (2) 6 500 20 nitrotoluene methoxy- simple an- 50 7 2-toluidine 100 N 100 Ethanol set according to a) 7 *) 674 38.3 1,4-butynediol water commercial 40 5 diols 161 61 3.6 common Pd catalyst *) Comparative experiment with a commercially available Pd catalyst.

Example 2 Commercially available 5 g of 5 ovo palladium on 950/0 alumina Catalyst were at room temperature together with 100 g of a 50% aqueous Copper acetate solution to which 5 cc of glacial acetic acid had been added, stirred. This mixture were with constant stirring within 15 minutes 2 cc of an 850% aqueous Hydrazine hydrate solution was added dropwise. The slurry became an additional 15 Stirred minutes and filtered to separate the catalyst.

Claims (2)

PATENT CLAIMS: 1. Process for the manufacture of a catalytic converter for the hydrogenation of organic compounds in the liquid state, characterized in that that one metallic, possibly on an inert, solid support finely divided palladium in the preferably 0.02 to 2.0 percent by weight copper salt containing, aqueous solution of a copper salt dispersed and that in the dispersion contained copper salt by reduction with a non-metallic reducing agent, preferably hydrogen or hydrazine, in metallic copper on the palladium precipitates. 2. The method according to claim 1, characterized in that one is a metallic palladium on charcoal or alumina in the aqueous copper salt solution dispersed and then reduced. Documents considered: German Auslegeschrift No. 1 002322.