Patent ID: 7842643
Filing Date: 2010-11-30
Classification: B01D,B01J

Abstract:
1. An exhaust gas purifying catalyst comprising: a catalyst substrate; and a catalyst coating layer formed on the catalyst substrate, the catalyst coating layer having a layered structure including: an inside layer a comprising an upstream portion located upstream relative to a flow direction of exhaust gas and a downstream portion located downstream relative to the flow direction of exhaust gas, the inside layer a containing (a-1) Pd, (a-2) Pt, and (a-3) an inorganic oxide; and an outside layer b, which covers both the upstream portion and the downstream portion of the inside layer, the outside layer b containing (b-1) a noble metal and (b-2) an inorganic oxide, wherein a part of (a-3) the inorganic oxide carries Pd and Pt so that a weight ratio Pd/Pt is within a range of 8 to 12, whereas the other part of (a-3) the inorganic oxide carries Pd and Pt so that a weight ratio Pd/Pt is within a range of 4 to 6 or within a range of 18 to 22, and in either of the upstream portion or the downstream portion, a weight ratio Pd/Pt, of Pd and Pt which is carried by he component of (a-3), is within a range of 8 to 12, whereas in the other one of the upstream portion and the downstream portion, a weight ratio Pd/Pt, of Pd and Pt which is carried by the component of (a-3), is within a range of 4 to 6 or within a range of 18 to 22.