Patent ID: 7429366

Claim:
A process for decomposing carbonyl sulfide and hydrogen cyanide contained in a mixed gas obtained by partially oxidizing heavy oil or coal, the mixed gas consisting essentially of hydrogen, carbon monoxide, steam and carbon dioxide and also containing impurities comprising hydrogen sulfide, carbonyl sulfide and hydrogen cyanide, which process comprises: contacting the mixed gas with a catalyst which comprises: (a) a carrier made of alumina and containing silica, and (b) chromium oxide carried by the carrier, thereby converting carbonyl sulfide and carbon dioxide according to the formula: COS+H 2 O→CO 2 +H 2 S (1) and converting hydrogen cyanide to ammonia, carbon monoxide and methane according to the following formulae: HCN+H 2 O→NH 3 +CO (2) and HCN+3H 2 →NH 3 +CH 4 (3), wherein chromium oxide is contained in an amount of 10 to 15 weight % in terms of Cr 2 O 3 relative to the catalyst and the catalyst has a BET specific surface area of 200 m 2 /g or greater, wherein the mixed gas has a temperature which is higher than a dew point of the mixed gas and is within the range of from 110 to 250° C., and wherein, in the catalyst, chromium oxide is carried on a surface of the carrier as a complex oxide compound.