| 摘要 |
PROBLEM TO BE SOLVED: To enhance the durability of NOx removal rate by preventing the formation of a sulfate in the pores of zeolite. SOLUTION: This catalyst for the purification of exhaust gas is composed of a carrier comprising a zeolite having an Si to Al molar ratio of <=150 and a metal oxide carrier, an oxygen occlusion-discharge material and a noble metal carried on at least the carrier outside the pores of the zeolite. Since the noble metal is not carried in the pores of the zeolite, the formation of a sulfate in the pores is prevented and the blocking of the pores due to the sulfate is also prevented. Therefore, the HC adsorbing ability is highly maintained even after use over a long period of time and NOx removing ability is enhanced. |
