| 摘要 |
<P>PROBLEM TO BE SOLVED: To provide an exhaust gas purification catalyst for improving catalytic performance so as to reduce the amount used of noble metals. <P>SOLUTION: The exhaust gas purifying catalyst 1 includes a catalyst substrate 3, and a catalyst coating layer 5, 7 which is formed on the catalyst substrate 3 and contains a noble metal and a refractory inorganic oxide. The exhaust gas purifying catalyst is characterized in that the catalytic coating layer 5, 7 has a layered structure including an A-layer 5 and a B-layer 7. The A-layer 5 contains Pd and Pt as the noble metal in a weight ratio of 3:1 to 20:1, while the B-layer 7 contains Rh as the noble metal. 70 wt.% or more of Pd and Pt contained in the A-layer 5 is in a region 9 from a surface of the A-layer to a depth of 20 μm. <P>COPYRIGHT: (C)2012,JPO&INPIT |
