EXHAUST GAS CLEANING CATALYST

摘要

PROBLEM TO BE SOLVED: To prevent SOx from reaching an NOx capturing layer, where SOx is captured. SOLUTION: A exhaust gas cleaning catalyst 5 disposed in the exhaust gas passage of an engine has a catalytic substrate 10, a porous NOx capturing layer 11 which coats the catalytic substrate 10 so as to at least temporarily capture NOx in exhaust gas and a porous SOx capturing layer 12 which coats the NOx capturing layer 11 so as to at least temporarily capture SOx in exhaust gas. The coating weight of the SOx capturing layer 12 per unit volume of the catalyst in a part of the catalytic substrate 10 on the upper stream side of exhaust gas is made larger than that in a part of the catalytic substrate 10 on the downstream side of exhaust to form a thick part 12a on the upper stream side of exhaust gas and a thin part 12b on the downstream side of exhaust gas.