Patent ID: 6846466

Claim:
A catalyst for purifying an exhaust gas, comprising: an upstream side catalyst disposed on an upstream side with respect to an exhaust gas flow and including: a first cylinder-shaped support having a plurality of through holes penetrating therethrough in an axial direction; a first fire resistant inorganic oxide loading layer being formed on inner surfaces demarcating the through holes; and a first catalyst ingredient being held by the first loading layer and being composed of a first noble metal; a downstream side catalyst disposed on a downstream side with respect to the exhaust gas flow and including: a second cylinder-shaped support having a plurality of through holes penetrating therethrough in an axial direction; a second fire resistant inorganic oxide loading layer being formed on inner surfaces demarcating the through holes; and a second catalyst ingredient being held by the second loading layer and being composed of a second noble metal; said upstream side catalyst being constituted by the first catalyst ingredient, being composed of at least one member selected from the group consisting of palladium, palladium and rhodium and palladium and platinum as the first noble metal, and the first loading layer, being composed of an alumina containing barium and lanthanum at least; and said downstream side catalyst being constituted by the second catalyst ingredient, being composed of at least one member selected from the group consisting of platinum, palladium and rhodium as the second noble metal, and the second loading layer, being composed of at least one member selected from the group consisting of an alumina containing lanthanum, cerium, a solid solution of cerium and zirconium and a solid solution of cerium, zirconium and yttrium.