Multilayered catalyst compositions

• US 7,922,988 B2
• Filed: 10/30/2009
• Issued: 04/12/2011
• Est. Priority Date: 08/09/2007
• Status: Active Grant

• Current Assignee: BASF Corporation (BASF SE)
• Original Assignee: BASF Corporation (BASF SE)
• Inventors: Svoboda, Glenn, Wassermann, Knut, Deeba, Michel, Rabinowitz, Harold, Siemund, Stephan, Wei, Xinyi, Kotrel, Stefan
• Primary Examiner(s): Vanoy; Timothy C
• Application Number:
  US12/609,622
• Publication Number:
  US 20100104491A1
• Time in Patent Office: 529 Days
• Field of Search: 502/527.12, 502/527.13, 423/213.2, 423/213.5, 423/213.7, 423/239.1, 423/245.3, 423/247, 422168-171, 422/177, 422/180, 422/181, 602/74, 602/82, 602/99, 603/02
• US Class Current: 423/213.2
• CPC Class Codes: B01D 2255/1023 Palladium
• CPC Class Codes: B01D 2255/1025 Rhodium
• CPC Class Codes: B01D 2255/9025 Three layers
• CPC Class Codes: B01D 2255/908 O2-storage component incorporated in the catalyst
• CPC Class Codes: B01D 53/945 characterised by a specific catalyst
• CPC Class Codes: B01D 53/9472 in different zones
• CPC Class Codes: B01D 53/9477 with catalysts positioned on separate bricks, e.g. exhaust systems
• CPC Class Codes: F01N 2370/02 used in catalytic reactors
• CPC Class Codes: F01N 2510/0682 having a discontinuous, uneven or partially overlapping coating of catalytic material, e.g. higher amount of material upstream than downstream or vice versa
• CPC Class Codes: F01N 2510/0684 having more than one coating layer, e.g. multi-layered coatings
• CPC Class Codes: F01N 3/2803 characterised by structure, by material or by manufacturing of catalyst support
• CPC Class Codes: Y02T 10/12 Improving ICE efficiencies

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. The catalytic material can be provided in layers such that a larger amount of oxygen storage component is provided in a downstream zone as compared to an upstream zone. For example, the upstream zone can be configured to have one, two, or three layers, and the downstream zone can be independently configured to have one, two, or three layers. 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.

Claims

1. An exhaust gas treatment system comprising:

a catalytic material having the capability of simultaneously catalyzing the oxidation of hydrocarbons and carbon monoxide and the reduction of nitrogen oxides and having an upstream zone and a downstream zone deposited on a carrier;

wherein in the upstream zone, the catalytic material comprises;

an inner layer on the carrier, the inner layer comprising a support and a palladium component;

an outer layer above the inner layer, the outer layer comprising a support and a rhodium component; and

a first oxygen storage component located in the inner layer, the outer layer, or both;

wherein in the downstream zone, the catalytic material comprises;

an inner layer on the carrier, the inner layer comprising a support and a palladium component;

an outer layer above the inner layer, the outer layer comprising a support and a rhodium component; and

a second oxygen storage component located in the inner layer, the outer layer, or both such that the second oxygen storage component is present in an amount that is greater than the amount of the first oxygen storage component.

2. The exhaust gas treatment system of claim 1, wherein the carrier comprises a first substrate the upstream zone and a second substrate such that the upstream zone is located on the first substrate and the downstream zone is located in the second substrate.

3. The exhaust gas treatment system of claim 1, wherein the upstream zone further comprises a middle layer located above the inner layer and below the outer layer, the middle layer comprising a support and an optional palladium component and an optional third oxygen storage component.

4. The exhaust gas treatment system of claim 1, wherein the downstream zone further comprises a middle layer located above the inner layer and below the outer layer, the middle layer comprising a support and an optional palladium component and an optional third oxygen storage component.

5. The exhaust gas treatment system of claim 1, wherein the first oxygen storage component is present in an amount in the range of 0.1 to 1.5 g/in³ and the second oxygen storage component is present in an amount in the range of 1.55 to 2.0 g/in³.

6. The exhaust gas treatment system of claim 1, wherein the outer layer of both the upstream zone and the downstream zone comprise the same composition.

7. The exhaust gas treatment system of claim 1, wherein the inner layer of both the upstream zone and the downstream zone comprise the same composition.

8. The exhaust gas treatment system of claim 1, wherein both the upstream and downstream zones each further comprises a middle layer located above the inner layer and below the outer layer, the middle layers each independently comprise a support, a palladium component, and a third oxygen storage component.

9. The exhaust gas treatment system of claim 1, wherein both the upstream and downstream zones each further comprises a middle layer located above the inner layer and below the outer layer, the inner layers of both the upstream and downstream zones each comprising the same composition.

10. The exhaust gas treatment system of claim 1, wherein the upstream zone extends for no more than 50% of the substrate'"'"'s length.

11. The exhaust gas treatment system of claim 1, wherein the downstream zone extends for no more than 50% of the substrate'"'"'s length.

12. The exhaust gas treatment system of claim 1, wherein the inner layer, the outer layer, or combinations thereof further independently comprise platinum, palladium, rhodium, or combinations thereof.

13. The exhaust gas treatment system of claim 1, wherein the inner and outer layers and of both the upstream and downstream zones are independently supported by an activated compound selected from the group consisting of alumina, silica-alumina, alumino-silicates, alumina-zirconia, and alumina-ceria.

14. A method for oxidizing hydrocarbons and carbon monoxide and reducing nitrogen oxides comprising:

contacting a gaseous stream comprising the hydrocarbons, carbon monoxide, and nitrogen oxides with the exhaust gas treatment system of claim 1.

15. The method of claim 14, wherein the carrier comprises a first substrate the upstream zone and a second substrate such that the upstream zone is located on the first substrate and the downstream zone is located in the second substrate.