DE1072972B - Process for the preparation of cobalt-containing hydrogenation catalysts - Google Patents

Description

Process for the preparation of cobalt-containing hydrogenation catalysts Cobalt-containing catalysts have long been used in hydrogenation. the technical cobalt catalysts are mostly applied to inert supports and contain small amounts of activated metals. For example, there is a hydrogenation catalyst known from cobalt, which contains about 0.5 to 100 / (chromium oxide or manganese oxide. For the technical usefulness of the catalyst is the durability of the same of crucial as it is in many processes, especially in continuous ones Procedure, is not possible to reactivate the catalysts during operation. Frequent interruptions in operation to reactivate the catalyst, mostly must be carried out outside the reaction chamber, or to replace the catalyst a new, fresh catalyst are often undesirable.

The purpose of the invention is the production of cobalt-containing hydrogenation catalysts, which also contain chromium and / or manganese and a pyro or polyacid residue and can be applied to a carrier.

It has now been found that suitable hydrogenation catalysts can be used for hydrogenations that work with high throughputs and those for longer Production periods should be worked without interruption, if one the mixture of the catalyst components or the one used to impregnate the carrier Metal salt solution small amounts of a free which can be converted into pyro- or polyform Acid is added and then heated.

A method is already known from US Pat. No. 2,726,195 after which hydrogenation catalysts containing pyrophosphates are prepared Has. In this process, however, one starts from metals that are precipitated as phosphates and as such are subjected to heat treatment by muffing. the However, the structure of the catalysts produced in this way differs considerably on the structure of the catalysts produced according to the invention, since the Acids in the process according to the invention in their free form, but not in the form their salts are applied.

In the process according to the invention, all acids that are used in Heating into the pyro or poly form, d. H. into the corresponding pyro- or polyacids, pass over, use, e.g. B. phosphoric acid, sulfuric acid or boric acid. The acids are preferably inert to the catalyst, which is optionally also supported and neutral supports, may be applied prior to heating, e.g. B. by muffle happens, added. The catalysts are, for example, by treating the Carrier materials applied with a metal salt solution, which is moderately the one in question Acid, e.g. B. the phosphoric acid added. You can do that with the catalyst solution soaked carrier muffles. In general, additions of 0.5 to 5 percent by weight are sufficient, advantageously 0.3 to 1.5 percent by weight of the acid, based on the amount by weight of the catalyst used in order to achieve the required durability. The catalysts are expediently heated at 350 to 7000 C in a muffle furnace. Using of phosphoric acid is advantageously heated to 500 to 6500 C.

But you can also apply the metal salt solution to the carrier applied metals for a long time at elevated temperature, e.g. B. 400 to 7000 C, muffle and only then add the acid and a subsequent heat treatment at lower temperatures the acids in the corresponding pyro- resp.

Transfer polyacids. In this case, heat treatment is sufficient at temperatures from 200 to 3500 C to give the catalyst the desired properties to rent. The heat treatment transforms the acids into their pyro or poly form transferred and effect by binding the active components to the carrier material or the special durability due to structural changes in the active components the catalysts.

But you can also use the catalysts as so-called full catalysts, d. H. without carrier. In this case, the catalyst components are in mixed in the desired proportion and at 0.05 to 5%, advantageously 0.3 up to 1.50 / o Phos phosphoric acid or sulfuric acid added and on it heated to a temperature at which the acids change into their pyro or poly form.

However, it is particularly advantageous to apply the process to manufacture of catalysts applied to supports. As a support for the catalysts you can use fuller's earth, silica strands, silica gel, aluminum oxide and silicates, such as B. use magnesium silicate.

The catalysts prepared by the process are suitable for all hydrogenation processes commonly used in organic chemistry that are used in technical Scale to be run; In particular, the use of those produced according to the invention is Catalysts are advantageous for hydrogenations in continuous operation. The catalysts can, for example, in the hydrogenation of aliphatic carboxylic acid nitriles, Dicarboxylic acid dinitriles are used to form amines or diamines. A special In addition to their durability, the advantage of the catalysts is the purity of the Hydrogenation products. In the hydrogenation of adipic acid dinitrile to hexamethylenediamine are attached to the hydrogenation product, the intermediate product for the manufacture of synthetic fibers is, very high purity requirements.

Traces of alkalis or alkaline earths cause the hydrogenation Formation of by-products that cannot be separated by distillation. Of the The value of the hexymethylene diamine obtained is therefore considerably reduced. By the However, a catalyst according to the invention is obtained in the basic Components are so firmly bound that they are not washed out by the hydrogenation product can be. In the case of thermal treatment, for example, those in the catalytic converter go Easily soluble o-silicic acid contained and the aluminum hydroxide in insoluble Polysilicic acid and insoluble aluminum oxide over. In this form they are as well the basic components that z. B. can come from the carrier material through the hydrogenation product is no longer soluble, thereby avoiding disruptive side reactions on the contrary, it increases the durability of the catalyst.

Since the catalysts prepared according to the invention at the same time a have increased activity, higher yields are achieved when they are used.

Example 1 It is produced by introducing 700 g of silica strands in a solution of 766 g cobalt nitrate (Co [N O3] 2 6 H2 0), 12 g chromium trioxide and 6 g of phosphoric acid in 800 ml of water, drying the mixture at 1100 C and muffles at 6500 C produced a catalyst in which the added phosphoric acid was converted into insoluble Pyrophosphate is transferred. After muffling the catalyst is put in a ball mill ground.

With the catalyst prepared in this way, 600 g of adiponitrile are obtained and 4200 grams of a mixture of 65 weight percent liquid ammonia and 35 weight percent crude hexamethylenediamine hydrogenated. 50 g of catalyst are used for the hydrogenation and works at 700 C and 300 at hydrogen pressure. After the hydrogen uptake has ceased the ammonia is evaporated and the diamine formed is filtered off warm from the catalyst away. A water-clear, crude hexamethylenediamine is obtained, which closes on cooling snow-white crystals solidified (solidification point 40> 10 C). During the distillation of The hydrogenation product gives a hexmethylenediamine in 98.20% yield with a solidification point of 410 C. The hydrogen uptake took place in 5 hours. If a catalyst without pyroacids or polyacids is used, hydrogen is required for uptake 11 hours. The life of the catalyst according to the invention is increased by 40%.

If the hexamethylenediamine obtained is converted into an aqueous AH salt solution with a p-value of 7.55 and heated to 850 C for 24 hours with access to air, so the solution has a color number of 18 Hazen units. Is aminocapronitrile also no longer detectable by chromatography, likewise o-diaminocyclohexane.

The same results are obtained if one takes the place of silica strands Aluminum oxide used as a carrier and treated with the solution described above.

Example 2 790 g of aluminum oxide are dissolved in a solution of 996 g of cobalt nitrate (Co [N ° 3] 2 to 6 H2 O), 19 g of chromium trioxide and 3 g of phosphoric acid in 800 ml of water registered. The mixture is dried at 1100.degree. C. and then at 5500.degree 30 hours muffled.

The catalyst is then ground in a ball mill.

This catalyst is, for example, for the hydrogenation of suberonitrile suitable. The hydrogenation gives a crude octamethylenediamine as water-clear Liquid that solidifies at 51.70 ° C. The salt solution prepared according to Example 1 with adipic acid has a color number of only 5 after heating at 850 C for 24 hours Hazen units.

Example 3 700 g of silica strands are mixed with a solution of 766 g cobalt nitrate (Co [N] 2 6H2O), 32 g manganese nitrate (Mn [NO] 2 6H2O) and 6 g phosphoric acid soaked in 800 ml of water. The soaked grains are dried at 1100 C and Calcined for 36 hours at 6000 C, the phosphoric acid in insoluble phosphates or polyphosphoric acid passes.

5000 kg of this catalyst are lighter in a 0.8 m furnace Wide and 18.0 m long filled and reduced with hydrogen.

The catalyst is initially charged with 450 kg of adiponitrile every hour and 800 kg of liquid ammonia are loaded until the reaction has fully started.

In stationary operation, one works at 300 atmospheres hydrogen pressure and uses much of the hydrogenation product that is circulated as Solvent. 800 kg of ammonia and 650 kg of adipic acid dinitrile are per hour Liquid circuit supplied and a corresponding proportion of hydrogenation product removed. A sample of the hydrogenation product gives a complete result after the ammonia has evaporated water-clear crude hexamethylenediamine with a solidification point of 40.20 C. The distillation results in addition to 0.40 / o hexamethyleneimine and 1.80 / o higher-boiling components 97.80 / 0 Pure hexamethylenediamine with a solidification point of 41.00 C. The color number test according to the example 1 indicates 15 Hazen units. e-aminocapronitrile and o-diaminocyclohexane are not verifiable.

The life of the catalyst is about 400/0 longer than that of the Use of a catalyst that does not contain phosphoric acid.

Claims (1)

PATENT CLAIM: Process for the production of cobalt-containing hydrogenation catalysts, which also contain chromium and / or manganese and a pyroic acid residue and on a carrier can be applied, characterized in that the mixture the catalyst components or the impregnation of the carrier used metal salt solution adding small amounts of a free acid which can be converted into the pyro or polyform and then heated. Documents considered: German Patent No. 814293; U.S. Patent No. 2,726,195.