Layered exhaust treatment catalyst

• US 20050282701A1
• Filed: 06/22/2004
• Published: 12/22/2005
• Est. Priority Date: 06/22/2004
• Status: Active Grant

• Current Assignee: BASF Corporation (BASF SE)
• Original Assignee: Engelhard Corporation (BASF SE)
• Inventors: Foong, John S., Hu, Zhicheng
• Granted Patent: US 7,795,172 B2
• Time in Patent Office: Days
• US Class Current: 502/304
• CPC Class Codes: B01D 2255/1021 Platinum
• CPC Class Codes: B01D 2255/1023 Palladium
• CPC Class Codes: B01D 2255/1025 Rhodium
• CPC Class Codes: B01D 2255/9022 Two layers
• 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: B01J 23/63 with rare earths or actinides
• CPC Class Codes: B01J 37/0244 Coatings comprising several layers
• CPC Class Codes: B01J 37/0248 Coatings comprising impregnated particles
• CPC Class Codes: Y02A 50/20 Air quality improvement or preservation, e.g. vehicle emission control or emission reduction by using catalytic converters
• CPC Class Codes: Y02T 10/12 Improving ICE efficiencies

Abstract

A layered exhaust treatment catalyst comprising: (a) a carrier such as cordierite; (b) a first layer deposited on the carrier comprising a palladium metal component, a platinum metal component and an oxygen storage component such as ceria supported on a refractory metal oxide such as gamma-alumina; and (c) a second layer deposited on the first layer comprising a rhodium metal component, a platinum metal component and an oxygen storage component such as ceria supported on a refractory metal oxide such as gamma-alumina. Preferably, the catalyst also includes a bottom layer interposed between the carrier and the first layer. The bottom layer comprises an oxygen storage component such as ceria supported on a refractory metal oxide such as gamma-alumina. The amount of the oxygen storage component of the catalyst may be “tuned”, i.e., adjusted, to meet the needs of a vehicle'"'"'s on-board diagnostic (“OBD”) catalyst efficiency monitoring system, without adversely affecting the performance of the catalyst.

Claims

1. A layered exhaust treatment catalyst comprising

(a) a carrier;

(b) a first layer deposited on the carrier, said first layer comprising a palladium metal component, a platinum metal component and an oxygen storage component supported on a refractory metal oxide, the ratio of the palladium metal component to the platinum metal component being in the range of about 5;

1 to about 200;

1; and

(c) a second layer deposited on the first layer comprising a rhodium metal component, a platinum metal component and an oxygen storage component supported on a refractory metal oxide, the ratio of the rhodium metal component to the platinum metal component being in the range of about 5;

1 to about 30;

1.

2. The catalyst of claim 1 further comprising a bottom layer interposed between the carrier and the first layer, said bottom layer comprising an oxygen storage component supported on a refractory metal oxide.

3. The catalyst of claim 2 wherein the oxygen storage component is present in the bottom layer, the first layer and the second layer in an amount of about 0.2 to about 2.0 g/in³.

4. The catalyst of claim 2 wherein the oxygen storage component employed in the bottom layer, first layer and second layer is independently selected from the group consisting of baria, ceria, lanthania, praseodymia, a ceria-praseodymia composite, a ceria-praseodymia-zirconia composite, a ceria-praseodymia-zirconia-neodymia composite and a ceria-lanthania-praseodymia-zirconia-neodymia composite.

5. The catalyst of claim 2 wherein the refractory metal oxide employed in the bottom layer, the first layer and the second layer is independently selected from the group consisting of alumina, zirconia, mixtures of alumina with zirconia and/or ceria, and ceria coated on alumina.

6. The catalyst of claim 2 wherein the refractory metal oxide employed in the bottom layer, the first layer and the second layer comprises gamma-alumina.

7. The catalyst of claim 1 wherein the total amount of palladium metal component and the platinum metal component employed in the first layer is in the range of about 10 to about 60 g/ft³.

8. The catalyst of claim 1 wherein the total amount of rhodium metal component and platinum metal component employed in the second layer is in the range of about 2 to about 15 g/ft³.

9. The catalyst of claim 1 wherein the carrier comprises a ceramic or metallic monolith.

10. The catalyst of claim 9 wherein the carrier comprises cordierite.

11. A layered exhaust treatment catalyst comprising:

(a) a carrier;

(b) a bottom layer disposed on the carrier, said bottom layer comprising an oxygen storage component supported on a refractory metal oxide;

(c) a first layer disposed on the bottom layer, said first layer comprising a palladium metal component, a platinum metal component and an oxygen storage component supported on a refractory metal oxide, the ratio of the palladium metal component to the platinum metal component being in the range of about 5;

1 to about 20;

1 and

(d) a second layer disposed on the first layer comprising a rhodium metal component, a platinum metal component and an oxygen storage component supported on a refractory metal oxide, the ratio of the rhodium metal component to the platinum metal component being in the range of about 5;

1 to about 20;

1.

12. The catalyst of claim 11 wherein the oxygen storage component is employed in the bottom layer, the first layer and the second layer in an amount of about 0.2 to about 2.0 g/in³.