Exhaust gas purifying catalyst
AssigneeCataler Corporation
InventorsYuji Yabuzaki, Kenichi Taki, Akimasa Hirai
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Abstract
An exhaust gas purifying catalyst exhibiting high catalytic performance and restraining an amount of noble metals used is provided. An exhaust gas purifying catalyst has a catalyst substrate and a catalyst coating layer formed on the catalyst substrate. The catalyst coating layer has a layered structure including an inside layer containing (a-1) Pd, (a-2) Pt, and (a-3) an inorganic oxide, and an outside layer containing (b-1) a noble metal and (b-2) an inorganic oxide. 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.
Claims9
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.
Dependencies are inferred from the claim text.