Patent ID: 8636959

Claim:
An exhaust gas purification catalyst equipment formed by arranging an oxidation catalyst (DOC) having an oxidative function for nitrogen monoxide and hydrocarbon and a selective catalytic reduction type catalyst (SROC) having an oxidative function layer in the subsequent stage thereof, in a flow path of exhaust gas, and a spraying means to supply an urea aqueous solution or an aqueous ammonia solution is arranged in the downstream of the aforementioned oxidation catalyst (DOC) and in the upstream of aforementioned selective catalytic reduction type catalyst (SROC), characterized in that the selective catalytic reduction type catalyst (SROC) comprises a lower-layer catalyst layer (A) having an oxidative function for nitrogen monoxide (NO) in exhaust gas and an upper-layer catalyst layer (B) having an adsorbing function for ammonia on the surface of a monolithic structure type carrier (C), and that the lower-layer catalyst layer (A) comprises the following components of (i), (ii) and (iii), and the upper-layer catalyst layer (B) comprises component (iii) and none of component (i), (i) one or more kinds of noble metals selected from platinum, palladium and rhodium; (ii) one or more kinds of oxides selected from alumina, titania, silica, zirconia, tungsten oxide, transition metal oxides, rare earth oxides, or composite oxide thereof; and (iii) zeolite; and wherein the content of zeolite in the lower-layer catalyst (A) per unit volume of the monolithic type carrier (C) is 80 g/L or less; and wherein the content of zeolite in the upper-layer catalyst layer (B) per unit volume of the monolithic type carrier (C) is 100 to 160 g/L.