GB827079A - Improvements in or relating to the production of alumina base catalysts - Google Patents

Abstract

In the production of an alumina-base catalyst comprising platinum, rhodium, palladium or iridium according to the parent Specification, the alumina base is prepared by dehydrating an alumina hydrate composition comprising 65-95% of crystalline alumina trihydrates prepared by forming an amorphous alumina hydrogel (e.g. by precipitation with ammonia from aluminium sulphate, nitrate or chloride, or by hydrolysis of aluminium isopropylate at 50-85 DEG F.), washing the hydrogel at 70-120 DEG F. and pH 7-9 and ageing at 70-130 DEG F. and pH 7-9. The composition comprises the crystalline trihydrates Gibbsite, Randomite and Bayerite together with Boehmite and amorphous alumina: if the maximum trihydrate yield is desired washing is conducted at 80-90 DEG F., if the maximum Randomite yield is desired the washing temperature should be 110-120 DEG F. In the example, an aluminium chloride solution is mixed with ammonium hydroxide solution at 80 DEG F., filtered and samples washed at various temperatures. The washed filter cake is reslurried at a pH of 9, stirred for an hour to age, filtered and rewashed at the same temperature. This sequence of steps is repeated and the nature of the samples determined by X-ray analysis. Thereafter a slurry of the alumina is mixed with a solution of chlorplatinic acid solution and subsequently with a hydrogen sulphide solution. The slurry is dried in a forced air oven at 110 DEG C., ground, mixed with a hydrogenated vegetable oil as die lubricant, formed into tablets and the lubricant burnt out in an air/nitrogen atmosphere at 900 DEG F. Thereafter it is calcined in air at 900 DEG F. and treated with hydrogen at the same temperature.