Exhaust gas-purifying catalyst
AssigneeCataler Corporation
InventorsYuji Yabuzaki, Akimasa Hirai, Kenichi Taki
Life of this patent
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Abstract
Decreasing HC emission is made possible. An exhaust gas-purifying catalyst includes a substrate, a hydrocarbon-adsorbing layer covering the substrate, and a catalytic layer covering the hydrocarbon-adsorbing layer. The catalytic layer includes a layered structure of a first catalytic layer including a precious metal and a carrier supporting it, and a second catalytic layer including the same precious metal as the precious metal of the first catalytic layer and a carrier supporting it and having a concentration of the precious metal higher than that in the first catalytic layer.
Claims17
An exhaust gas-purifying catalyst comprising:
- a substrate;
- a hydrocarbon-adsorbing layer covering the substrate;
- and
- a catalytic layer covering the hydrocarbon-adsorbing layer, wherein the catalytic layer includes a layered structure of a first catalytic layer including a precious metal and a carrier supporting it, and a second catalytic layer including the same precious metal as the above precious metal and a carrier supporting it, a concentration of the precious metal in the second catalytic layer being higher than that in the first catalytic layer, wherein each of the first and second catalytic layers includes palladium, a concentration of palladium in the second catalytic layer being higher than that in the first catalytic layer, and wherein each of the first and second catalytic layers further includes rhodium, a concentration of rhodium in the second catalytic layer being higher than that in the first catalytic layer.
An exhaust gas-purifying catalyst comprising:
- a substrate;
- a hydrocarbon-adsorbing layer covering the substrate;
- and
- a catalytic layer covering the hydrocarbon-adsorbing layer, wherein the catalytic layer includes a layered structure of a first catalytic layer including a precious metal and a carrier supporting it, and a second catalytic layer including the same precious metal as the above precious metal and a carrier supporting it, a concentration of the precious metal in the second catalytic layer is higher than that in the first catalytic layer, and
- each of the first and second catalytic layers includes rhodium, a concentration of rhodium in the second catalytic layer being higher than that in the first catalytic layer.
An exhaust gas-purifying catalyst comprising:
- a substrate;
- a hydrocarbon-adsorbing layer covering the substrate;
- and
- a catalytic layer covering the hydrocarbon-adsorbing layer, wherein the catalytic layer includes a layered structure of a first catalytic layer including a precious metal and a carrier supporting it, and a second catalytic layer including the same precious metal as the above precious metal and a carrier supporting it, a concentration of the precious metal in the second catalytic layer is higher than that in the first catalytic layer, each of the first and second catalytic layers includes palladium, a concentration of palladium in the second catalytic layer is higher than that in the first catalytic layer, and the first catalytic layer is interposed between the substrate and the second catalytic layer, wherein each of the first and second catalytic layers further includes rhodium, a concentration of rhodium in the second catalytic layer being higher than that in the first catalytic layer.
Dependencies are inferred from the claim text.