GB387992A - Improvements in the combustion of ammonia - Google Patents

Abstract

Catalysts for the oxidation of ammonia are made by alloying platinum or an alloy of platinum metals with one or more metals of the 5th and 6th groups of the periodic system. Examples of the latter are tantalum, tungsten, molybdenum, niobium, chromium, uranium, and vanadium. They may be added in proportions up to 60 per cent but 1-5 per cent is usually sufficient. The catalyst should be of large surfaced form such as netting, perforated sheets, pills, chips, wires, or spirals. Two or more layers of netting &c. of different composition may be used. According to one example of preparation of an alloy, platinum or an alloy thereof is galvanically coated with blue tungsten oxide in a bath of pertungstic acid. It is washed, dried, reduced in hydrogen, and heated for several hours at 1000-1100 DEG C. in a hydrogen atmosphere whereupon the tungsten diffuses into the platinum. In other examples the alloys are made by fusing the constituents together in a reducing atmosphere.ALSO:Catalysts for ammonia oxidation are made by alloying platinum or an alloy of platinum metals with one or more metals of the 5th p and 6th groups of the periodic system. Examples of the latter are tantalum, tungsten, molybdenum, niobium, chromium, uranium, and vanadium. They may be added in proportions up to 60 per cent but 1-5 per cent is usually sufficient. According to one example platinum or an alloy thereof is galvanically coated with blue tungsten oxide in a bath of pertungsten acid. It is washed, dried, reduced in hydrogen, and heated for several hours at 1000-1100 DEG C. in a hydrogen atmosphere, whereupon the tungsten diffuses into the platinum. In other examples the alloys are made by fusing the constituents together in a reducing atmosphere.