CATALYST FOR PURIFICATION OF EXHAUST GAS

摘要

PROBLEM TO BE SOLVED: To obtain a catalyst for the purification of exhaust gas used for reducing and removing NOx contained in exhaust gas containing excess oxygen and capable of retaining high catalytic activity even to SOx-containing exhaust gas over a long period of time. SOLUTION: The catalyst contains a powdery porous oxide with a supported noble metal, powdery ZSM-5 and a powdery CeO2-ZrO2 solid solution. Since the noble metal is previously supported on the powdery porous oxide, the probability of contact of the noble metal with the ZSM-5 and the CeO2-ZrO2 solid solution lowers. Since the ZSM-5 is excellent in HC adsorptivity and the CeO2-ZrO2 solid solution has high oxygen occluding and discharging ability and high heat resistance, the covering of the noble metal with accumulated SOx as well as the grain growth of the noble metal is suppressed.