Patent ID: 8158552

Claim:
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) containing a component (a-1) and a component (a-2); and an outside layer (b) containing a component (b-1) and a component (b-2), and a ratio of the component (a-1) to the component (b-1) being within 3.5:1 to 1.1:1, wherein Component (a-1): at least one member selected from the group consisting of Pd and Pt; Component (a-2): a compound oxide of (I) Ce, (ii) Zr, and (iii) an element selected from a group consisting of rare earth elements, alkaline earth elements and Y, the compound oxide of Component (a-2) having a ratio of (ii) to (I) within a range of more than 50/100 but not more than 100/70 in terms of weight ratio between CeO 2 and ZrO 2 ; Component (b-1): noble metal including at least Rh; and Component (b-2): a compound oxide of elements selected from a group consisting of (iv) Ce, (v) Zr, and (vi) an element selected from a group consisting of rare earth elements, alkaline earth elements and Y, the compound oxide of Component (b-2) having a ratio of (v) to (iv) of not more than 20/100 in terms of weight ratio between CeO 2 and ZrO 2 , the outside layer (b) includes a surface layer region and a region other than the surface layer region, the surface layer region contains an amount of the noble metal component (b-1) and the amount of the noble metal component (b-1) contained in the surface layer region is smaller than an amount of the noble metal component (b-1) contained in the region other than the surface layer region in the outside layer (b).