PURPOSE: To prolong the life of reduction catalyst by having catalyst content, consisting of a specific quantity of iron and/or cobalt and manganese oxide and platinum group metal blended, carried on a carrier constituted with silica and/or alumina.
CONSTITUTION: First, platinum group metal is carried on a carrier constituted of silica and/or alumina. Next, iron and/or cobalt and manganese oxide are carried simultaneously, and thus prepared ternary composition catalyst is heat treated at a temperature of 500-950oC in the presence of reductive atmosphere, for example, hydrogen, to form a reduction catalyst. At this time, the blending quantity of iron and/or cobalt should be 15-25 % based on the whole weight of catalyst including the carrier. Silica carrier having at most 500 m2/g of specific surface area is suitable, while alumina carrier having at most 380 m2/g of specific surface area is suitable