Multilayered catalyst compositions
AssigneeBASF Catalysts LLC
InventorsMichel Deeba, Knut Wassermann, Glenn Svoboda, Harold Rabinowitz, Stephan Slemund, Xinyi Wei
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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 system and methods of using the same are also provided. In one or more embodiments, the catalyst supported on a carrier has three layers, where at least two of the layers are zoned to have an oxygen storage component being present in an upstream zone in an amount that is less than the oxygen storage component present in the downstream zone.
Claims23
An exhaust gas treatment system comprising:
- a catalytic material deposited on a carrier, the carrier comprising a longitudinal axis, an upstream end, a downstream end, having a length extending between the inlet end to the outlet end;
- the catalytic material comprising:
- an inner layer having an inner layer upstream zone and an inner layer downstream zone deposited on the carrier, the inner layer comprising a first support, being substantially free of precious metals, and, optionally, comprising a first oxygen storage component;
- a middle layer having a middle layer upstream zone and a middle layer downstream zone, the middle layer comprising a second support, a palladium component, and, optionally, a second oxygen storage component;
- and
- an outer layer having an outer layer upstream zone and an outer layer downstream zone, the outer layer comprising a third support, a rhodium component, and, optionally, a third oxygen storage component;
- wherein at least two of the first oxygen storage component, the second oxygen storage component, and the third oxygen storage component are present in the inner layer downstream zone, the middle layer downstream zone, and the outer layer downstream zone, respectively, in amounts greater than in the inner layer upstream zone, the middle layer upstream zone, and the outer layer upstream zone, respectively.
A method for oxidizing hydrocarbons, carbon monoxide, and nitrogen oxides comprising:
- contacting a gaseous stream comprising the hydrocarbons, carbon monoxide, and nitrogen oxides with an exhaust gas treatment system comprising:
- a catalytic material deposited on a carrier, the carrier comprising a longitudinal axis, an upstream end, a downstream end, having a length extending between the inlet end to the outlet end;
- the catalytic material comprising:
- an inner layer having an inner layer upstream zone and an inner layer downstream zone deposited on the carrier, the inner layer comprising a first support, being substantially free of precious metals, and, optionally, comprising a first oxygen storage component;
- a middle layer having a middle layer upstream zone and a middle layer downstream zone, the middle layer comprising a second support, a palladium component, and, optionally, a second oxygen storage component;
- and
- an outer layer having an outer layer upstream zone and an outer layer downstream zone, the outer layer comprising a third support, a rhodium component, and, optionally, a third oxygen storage component;
- wherein at least two of the first oxygen storage component, the second oxygen storage component, and the third oxygen storage component are present in the inner layer downstream zone, the middle layer downstream zone, and the outer layer downstream zone, respectively, in amounts greater than in the inner layer upstream zone, the middle layer upstream zone, and the outer layer upstream zone, respectively.
Dependencies are inferred from the claim text.