PURPOSE: To remove nitrogen oxide, carbon monoxide and hydrocarbon from oxygen excessive exhaust gas containing nitrogen oxide, carbon monoxide and hydrocarbon with high purifying efficiency by using zeolite containing palladium and phosphorus or cobalt, palladium and phosphorus as a catalyst.
CONSTITUTION: Ferrierite or ZSM-5 being crystalline aluminosilicate having a compsn. represented by xM2/nO.Al2O3.ySiO2.zH2O (wherein n is the valency of a cation M, x is 0.8-1.2, y is 2 or more and z is 0 or more) and characterized by that an SiO2/Al2O3mol ratio is 10 or more is used. Palladium and phosphorus or cobalt, palladium and phosphorus are infiltrated into this zeolite by an ion exhange method or an impregnation supporting method. The catalyst thus obtained is used in the purification of the exhaust gas from an internal combustion engine.
KAWAI YOSHIAKI
KAWAGUCHI TAKUYA
NAKANO MASAO
