Silver-containing supported catalysts and catalyst intermediate products, processes for their preparation and their use

An intermediate product for the preparation of a supported catalyst containing silver prepared by a process comprising the steps of:

• (a) impregnating a support whose specific surface area is at most 1 square meter per gram with lactic acid containing silver ions;
• and
• (b) drying the so-impregnated support in a virtually oxygen-free atmosphere at a temperature of 50.degree. to about 120.degree. C. to preliminarily decompose the lactic acid present in ionic form or in the free form and thereafter continuing preliminary decomposition by subjecting the so-dried composition to temperatures in two temperature ranges, from 140.degree. to 200.degree. C. and from 400.degree. to about 500.degree. C., the heating up range between the 140.degree.-220.degree. C. and 400.degree. to 500.degree. C. range being at a rate of 70.degree. to 150.degree. C. per hour and thereafter cooling the intermediate product in a virtually oxygen free atmosphere to about 70.degree. to about 80.degree. C. or below.

A process for the preparation of a supported catalyst containig silver which comprises the steps of:

• (a) contacting a support whose specific surface area is at most 1 square meter per gram with lactic acid containing silver;
• (b) drying the so-impregnated support in a virtually oxygen-free atmosphere at about 50.degree. to about 120.degree. C. and preliminarily decomposing the lactic acid present in ionic form or in free form by subjecting the same successively to two temperature ranges, one from about 140.degree. to 220.degree. C. and a second from 400.degree. to 500.degree. C., in a virtually oxygen-free atmosphere, the heating up rate from the temperature range of 140.degree.-220.degree. C. to the temperature range of 400.degree. to 500.degree. C. being 70.degree. to 150.degree. C. per hour;
• (c) activating the product obtained by step (b) by heating the same in an oxygen-containing atmosphere, the temperature being increased from at least 130.degree. C. to at most 300.degree. C. employing a heating-up rate of about 3.degree. to about 8.degree. C. per hour with increasing oxygen concentration from 0.4 to about 21 percent by volume in such a manner that the CO.sub.2 content of the off-gas from the activation does not exceed 1% by volume.

A process for the preparation of catalyst intermediate product which comprises:

• (a) impregnating an alumina support whose specific surface area is at most 1 square meter per gram with lactic acid containing silver;
• (b) drying the so-impregnated product in a virtually oxygen-free atmosphere at about 50.degree. to about 120.degree. C. and preliminarily decomposing the lactic acid, present in ionic form or in the free form, by subjecting it successively to temperatures in two different ranges, one of which is 140.degree. to 220.degree. C. and the second of which is 400.degree. to 500.degree. C., in a virtually oxygen-free atmosphere, employing a heat up rate from the 140.degree.-220.degree. C. range to the 400.degree.-500.degree. C. range of 70.degree. to 150.degree. C. per hour and thereafter cooling the so-heated support in a virtually oxygen-free atmosphere to about 70.degree. to 80.degree. C. or below.