Exhaust gas treatment system
AssigneeEngelhard Corporation
InventorsShiang Sung, Harold N. Rabinowitz, Rudolf M. Smaling
Life of this patent
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Abstract
The present invention relates to an exhaust gas treatment catalytic article having an upstream catalytic zone and at least one downstream catalytic zone. The upstream catalytic zone has an upstream composition which has a first upstream support, and at least one first upstream palladium component. The upstream zone can have one or more layers. The downstream catalytic zone has a first downstream layer which has a first downstream support and a first downstream precious metal component. A second downstream layer has a second downstream support and a second downstream precious metal component.
Claims51
An exhaust gas treatment catalytic article comprising:
- an upstream catalytic zone and at least one downstream catalytic zone, the upstream catalytic zone comprising:
- an upstream composition comprising;
- a first upstream support, and
- at least one first upstream palladium component, there being a sufficient amount of the upstream palladium component to result in a 50 percent conversion at 200.degree. C. to 350.degree. C. for the oxidation of hydrocarbons, and
- wherein the upstream composition has substantially no oxygen storage components;
- and
- the downstream catalytic zone comprising:
- a first downstream layer comprising;
- a first downstream support,
- a first downstream precious metal component,
- a second downstream layer comprising;
- a second downstream support,
- a second downstream precious metal component,
- wherein at least one of the first and second downstream layers comprises a palladium component;
- and
- wherein the upstream composition has a lower light-off temperature than the downstream composition.
An exhaust gas treatment catalytic article comprising:
- an upstream catalytic zone and at least one downstream catalytic zone, the upstream catalytic zone comprising:
- a first upstream layer and a second upstream layer,
- the first upstream layer comprising;
- a first upstream support, and
- at least one first upstream palladium component,
- the second upstream layer comprising;
- a second upstream support,
- at least one second upstream palladium component;
- and
- the downstream catalytic zone comprising:
- a first downstream layer comprising;
- a first downstream support,
- a first downstream precious metal component,
- a second downstream layer comprising;
- a second downstream support,
- a second downstream precious metal component,
- wherein one of the first and second downstream layers comprises a palladium component and the other layer comprises a rhodium component.
Dependencies are inferred from the claim text.