PREPARATION OF CATALYST FOR PURIFYING EXHAUST GAS

PURPOSE:To obtain a catalyst for oxidizing and purifying exhaust gas whose activity is not deteriorated even in use at high temp., by molding a kneaded mixture of calcium aluminate and an aggregate into a honeycomb shape and, after drying, applying heat-treatment to the molded carrier at 800-1,000 deg.C before supporting a platinum group metal by said carrier. CONSTITUTION:An aggregate such as silica or titanium dioxide subjected to melting treatment and a molding aid such as carboxy methyl cellulose are added to and mixed with calcium aluminate and water is added to the resulting mixture to perform kneading. This kneaded mixture is molded into a honeycomb shape and solidified, aged and dried to obtain a honeycomb shaped carrier. This honeycomb shaped carrier is heat-treated at about 800-1,000 deg.C for 5min or more and allowed to support platinum and palladium to be subjected to reducing treatment at 300 deg.C or more. The obtained catalyst has the carrier having a specific surface area of 15-20m /g and hardly changes at 800 deg.C or more and shows no lowering in its activity even when the catalyst is used in a combuster having high use temp. and heated to 800 deg.C or more.