DE603687C - Process for the production of catalysts for ammonia synthesis - Google Patents

Description

Process for the preparation of catalysts for the synthesis of ammonia The patent 567 728 relates to a method of making a catalyst for the ammonia synthesis, according to which alkali or alkaline earth cyanogen compounds in the Ratio of 1/4 up to 1 equivalent of acid to 1 equivalent of complex cyano compound mixed with acid and evaporated. According to one embodiment of this older one Process are the complex cyanide substances such. B. alkali silicates, added, the carrier substances for the complex cyanides in the acid treatment resulting catalyst base material. According to the present invention the substances acting as carrier substances, which at the same time increase the effectiveness of the catalyst increase, soluble in acid, but precipitable by hydrolysis and difficult to melt Metal oxides, and they are supposed to be introduced into the catalyst as a result, that one acid containing such substances on the alkali or alkaline earth metal cyanides Brings influence. Suitable substances are compounds of zirconium, aluminum and thorium and the rare earths. The use of zircon, which z. B. dissolved in hydrochloric acid can be, has been found to be very effective for carrying out the claimed method proven. With the hydrochloric acid solution of zirconium, the alkali or alkaline earth iron cyan compounds steamed to dryness. If necessary, it is used to compensate for excess acid add a small amount of the alkali or alkaline earth iron cyan salt to the evaporated precipitate, z. B. potassium ferrocyanide, in aqueous solution and repeated the drying.

EXAMPLE 42 g of potassium ferrocyanide are dissolved in 150 cc of warm water and 309 g of concentrated hydrochloric acid containing 59 zirconium dioxide or the equivalent amount of zirconium hydroxide or zirconium oxychloride are added. After the mixture has been evaporated, the residue is stirred with about 5 g of potassium ferrocyamide dissolved in a sufficient amount of water and dried again. After previous treatment with a pure nitrogen-hydrogen mixture at 400 °, it can be used as a catalyst and gives a yield of 13 percent by volume of ammonia.

For comparison, the following experiment was carried out, which only yielded one yield of 7 volume percent ammonia.

42 g of potassium ferrocyanide were dissolved in 150 cc of water, 309 g of concentrated hydrochloric acid were added and the mixture was evaporated. 5 g of solid zirconium dioxide were added to the evaporation residue. This mixture was made with about 5 g of potassium ferrocyanide; which was dissolved in sufficient amount of water, rubbed in. After drying, the dry residue was carefully heated to a temperature of q.00 ° while a pure nitrogen-hydrogen mixture was passed through and used for catalysis under the following operating conditions: pressure: 80 to 90 atm, temperature: 40 ° C., flow rate: 6 l / g / hour.

The result was a yield of about 7 vol% ammonia.

Claims (1)

PATENT CLAIMS: i. Process for the production of catalysts for the ammonia synthesis according to claim q. of patent 567 728, characterized in that that for the treatment of the alkali metal or alkaline earth metal cyanide compounds used acids which the carrier substances to be inserted into the catalyst in the form of easily contain hydrolytically splitting compounds. a. Method according to claim i, characterized in that the alkali or alkaline earth iron cyanide salts with zinc opium Dissolved hydrochloric acid containing treated and evaporated. 3. Procedure according to Claims i and z, characterized in that the reaction product evaporated to dryness Again mixed with alkali or alkaline earth iron cyanide salt and dried again will.