DEVICE FOR PURIFYING EXHAUST GAS FROM ENGINE

摘要

PURPOSE:To suppress the poisoning of Pd due to S and to improve the low- temp. HC acitvity of a catalyst with Pd as the catalystic component. CONSTITUTION:A catalyst 1 with Pd depositing on a base material component is placed in an exhaust gas passage 2 to constitute the device for purifying the exhaust gas from an engine. An air pipe 3 to supply air in the specified mode is furnished on the upstream side of the catalyst 1, and an SO2 sensor 5 and an exhaust gas temp. sensor 6 are installed in the passage 2 on the upstream side of the catalyst 1. The detection signals of the sensors 5 and 6 are inputted to an engine control unit 4 to control the air pump based on the information. The catalyst 1 consists of a honeycomb carrier 10, a base coat layer 20 obtained by depositing Pd on Al2O3 as the first catalyst bed and an overcoat layer 30 formed by depositing Pd on CeO2 as the second catalyst bed.