Multilayered Catalyst Compositions
First Claim
1. A layered catalyst composite comprising:
- a catalytic material on a carrier, the catalytic material comprising first, second, and third layers, the first layer comprising a first precious metal selected from a first rhodium component on a first support, the second layer comprising a second precious metal selected from a second rhodium component on a second support, and the third layer comprising a third precious metal component on a third support;
wherein the catalytic material is effective to substantially simultaneously oxidize carbon monoxide and hydrocarbons and reduce nitrogen oxides.
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Abstract
A layered, three-way conversion catalyst having the capability of simultaneously catalyzing the oxidation of hydrocarbons and carbon monoxide and the reduction of nitrogen oxides is disclosed. Engine exhaust treatment systems including such catalysts are also provided. The catalyst generally comprises three layers in conjunction with a carrier. The three layers comprise two rhodium-containing layers and one palladium-containing layer. The two rhodium layers can be adjacent to each other, or they can be separated by another precious metal-containing layer. At least one of the two layers comprising the rhodium component comprises an oxygen storage component. Methods of making and using these catalysts are also provided.
89 Citations
26 Claims
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1. A layered catalyst composite comprising:
- a catalytic material on a carrier, the catalytic material comprising first, second, and third layers, the first layer comprising a first precious metal selected from a first rhodium component on a first support, the second layer comprising a second precious metal selected from a second rhodium component on a second support, and the third layer comprising a third precious metal component on a third support;
wherein the catalytic material is effective to substantially simultaneously oxidize carbon monoxide and hydrocarbons and reduce nitrogen oxides. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14)
- a catalytic material on a carrier, the catalytic material comprising first, second, and third layers, the first layer comprising a first precious metal selected from a first rhodium component on a first support, the second layer comprising a second precious metal selected from a second rhodium component on a second support, and the third layer comprising a third precious metal component on a third support;
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15. An exhaust gas treatment system comprising a combination of a first composite and a second composite, wherein the first composite comprises a first inner layer deposited on a first carrier comprising a palladium component and a support, a first middle layer deposited on the first inner layer, the first middle layer comprising a rhodium component and a support, and a first outer layer deposited on the first middle layer, the first outer layer comprising a palladium and a support;
- and wherein the second composite comprises a second inner layer deposited on the first carrier or on a second carrier, the second inner layer comprising a rhodium component and a support, a second middle layer deposited on the second inner layer, the second middle layer comprising a palladium component and a support, and a second outer layer deposited on the second middle layer, the second outer layer comprising a rhodium component and a support.
- View Dependent Claims (16, 17)
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18. A method for treating a gas comprising hydrocarbons, carbon monoxide, and nitrogen oxides comprising:
- contacting the gas with a catalytic material on a carrier, the catalytic material comprising three layers, wherein at least two layers each comprise a rhodium component and a support, the support of one of the at least two layers comprises an oxygen storage component, and a third layer comprises a precious metal component and a support;
wherein the catalytic material is effective to substantially simultaneously oxidize the carbon monoxide and the hydrocarbons and reduce the nitrogen oxides. - View Dependent Claims (19, 20)
- contacting the gas with a catalytic material on a carrier, the catalytic material comprising three layers, wherein at least two layers each comprise a rhodium component and a support, the support of one of the at least two layers comprises an oxygen storage component, and a third layer comprises a precious metal component and a support;
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21. A method of making a layered catalyst composite, the method comprising providing a carrier and coating the carrier with first, second, and third layers of catalytic material;
- wherein at least two layers each comprise a rhodium component, one of the at least two layers comprising the rhodium component comprises an oxygen storage component, and a third layer comprises a precious metal component and a support.
- View Dependent Claims (22, 23)
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24. A layered catalyst composite comprising:
- a catalytic material on a carrier, the catalytic material comprising an inner layer, a middle layer, and an outer layer, the inner layer deposited on the carrier comprising a first rhodium component on a first support, the middle layer deposited on the inner layer comprising a palladium component on a second support, and the outer layer deposited on the middle layer comprising a second rhodium component on a third support;
wherein the catalytic material is effective to substantially simultaneously oxidize carbon monoxide and hydrocarbons and reduce nitrogen oxides;
wherein the catalytic material comprises the rhodium components in amounts to provide a rhodium loading in the catalytic material in the range of 1 to 14 g/ft3, and the catalytic material comprises the palladium component in an amount to provide a palladium loading in the catalytic material in the range of 5 to 200 g/ft3. - View Dependent Claims (25, 26)
- a catalytic material on a carrier, the catalytic material comprising an inner layer, a middle layer, and an outer layer, the inner layer deposited on the carrier comprising a first rhodium component on a first support, the middle layer deposited on the inner layer comprising a palladium component on a second support, and the outer layer deposited on the middle layer comprising a second rhodium component on a third support;
Specification