Gasoline engine emissions treatment systems having particulate traps

• US 8,173,087 B2
• Filed: 02/04/2009
• Issued: 05/08/2012
• Est. Priority Date: 02/05/2008
• Status: Active Grant

• Current Assignee: BASF Corporation (BASF SE)
• Original Assignee: BASF Corporation (BASF SE)
• Inventors: Wei, Junmei, Wassermann, Knut, Li, Yeujin
• Primary Examiner(s): VANOY, TIMOTHY C
• Application Number:
  US12/365,182
• Publication Number:
  US 20090193796A1
• Time in Patent Office: 1,189 Days
• Field of Search: 423/213.2, 423/213.5, 423/245.3, 423/247, 423/239.1, 423/215.5, 602/99, 602/76, 602/97, 555/24, 55D/IG.30
• US Class Current: 423/213.2
• CPC Class Codes: B01D 2251/2067 Urea
• CPC Class Codes: B01D 2255/1023 Palladium
• CPC Class Codes: B01D 2255/1025 Rhodium
• CPC Class Codes: B01D 2255/9045 in parallel
• CPC Class Codes: B01D 2255/908 O2-storage component incorporated in the catalyst
• CPC Class Codes: B01D 2258/012 Diesel engines and lean burn gasoline engines
• CPC Class Codes: B01D 53/927 Successive elimination of carbon monoxide or hydrocarbons and nitrogen oxides
• CPC Class Codes: B01D 53/9418 for removing nitrogen oxides by selective catalytic reduction [SCR] using a reducing agent in a lean exhaust gas
• CPC Class Codes: B01D 53/9422 for removing nitrogen oxides by NOx storage or reduction by cyclic switching between lean and rich exhaust gases (LNT, NSC, NSR)
• CPC Class Codes: B01D 53/9445 Simultaneously removing carbon monoxide, hydrocarbons or nitrogen oxides making use of three-way catalysts [TWC] or four-way-catalysts [FWC]
• CPC Class Codes: B01D 53/9477 with catalysts positioned on separate bricks, e.g. exhaust systems
• CPC Class Codes: F01N 13/009 having two or more separate purifying devices arranged in series
• CPC Class Codes: F01N 13/0097 the purifying devices are arranged in a single housing
• CPC Class Codes: F01N 13/011 having two or more purifying devices arranged in parallel
• CPC Class Codes: F01N 2250/02 filtering and catalytic conversion
• CPC Class Codes: F01N 2250/12 absorption or adsorption, and catalytic conversion
• CPC Class Codes: F01N 2250/14 absorption or adsorption, and filtering
• CPC Class Codes: F01N 2570/10 Carbon or carbon oxides
• CPC Class Codes: F01N 2570/12 Hydrocarbons
• CPC Class Codes: F01N 2570/14 Nitrogen oxides
• CPC Class Codes: F01N 3/033 : in combination with other devices with adsorbents or absorbents F01N3/0821
• CPC Class Codes: F01N 3/0814 : combined with catalytic converters, e.g. NOx absorption/storage reduction catalysts
• CPC Class Codes: F01N 3/0821 : combined with particulate filters catalysed diesel particulate filters F01N3/035
• CPC Class Codes: F01N 3/2066 : Selective catalytic reduction [SCR]
• 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

Provided are exhaust systems and components suitable for use in conjunction with gasoline direct injection (GDI) engines to capture particulates in addition to reducing gaseous emission such as hydrocarbons, nitrogen oxides, and carbon monoxides. Exhaust treatment systems comprising a three-way conversion (TWC) catalyst located on a particulate trap are provided. An exemplary particulate trap is a soot filter. Additional treatment components can be added downstream of the particulate trap, including NO_x traps and SCR catalysts. The TWC catalyst can be coated on both the inlet side and the outlet side of the particulate trap. Alternatively, an oxidation catalyst can be deposited on a particulate trap. Methods of making and using the same are also provided.

Claims

1. An emission treatment system downstream of a gasoline direct injection engine for treatment of an exhaust system comprising hydrocarbons, carbon monoxide, nitrogen oxides, and particulates, the emission treatment system comprising a catalyzed particulate trap having a three-way conversion catalyst comprising an oxygen storage component deposited thereon;

one or more gas sensors, and an on-board diagnostic (OBD) system;

wherein an inlet side of the particulate trap comprises a layer of the three-way conversion catalyst thereon that has a thickness in the range of 10 to 50 microns.

2. The emission treatment system of claim 1, wherein an inlet side or an outlet side of the particulate trap is coated with a washcoat comprising palladium, a support, and an oxygen storage component.

3. The emission treatment system of claim 2, wherein the oxygen storage component is present in an amount of up to 10% by weight of the wash coat.

4. The emission treatment system of claim 1, wherein an inlet side or an outlet side of the particulate trap is coated with a washcoat comprising rhodium, a support, and an oxygen storage component.

5. The emission treatment system of claim 4, wherein the oxygen storage component is present in an amount of 10 to 25% by weight of the wash coat.

6. The emission treatment system of claim 1, wherein both an inlet side and an outlet side of the particulate trap are coated with a washcoat comprising a precious metal component selected from palladium, platinum, or both;

a support; and

an oxygen storage component.

7. The emission treatment system of claim 1 further comprising a NOx trap, an SCR catalyst, or both located downstream of the catalyzed particulate trap.

8. The emissions treatment system of claim 1, wherein 50% or more of anoverall platinum group metal (PGM) loading is deposited on an upstream 20-50% axial distance of the filter, and 50% or less of the overall PGM loading is deposited on a rear 50-80% axial distance of the filter.

9. The emissions treatment system of claim 1, wherein the catalyzed particulate trap comprises a catalyzed particulate filter having a porosity in the range of 50% to 59%.

10. The emissions treatment system of claim 1, wherein the catalyzed particulate trap comprises a catalyzed particulate filter that exhibits emissions conversions comparable to a flow-through substrate at a constant precious metal loading.

11. The emissions treatment system of claim 1, wherein the catalyzed particulate trap comprises a catalyzed particulate filter that exhibits a pressure drop comparable to an uncoated filter.

12. A method of treating an exhaust gas comprising hydrocarbons, carbon monoxide, nitrogen oxides, and particulates, the method comprising:

locating an emissions treatment system downstream of a gasoline direct injection engine;

providing a catalyzed particulate trap that comprises a three-way conversion (TWC) catalyst comprising an oxygen storage component deposited on a particulate trap in the emissions treatment system wherein an inlet side of the particulate trap comprises a layer of the three-way conversion catalyst thereon that has a thickness in the range of 10 to 50 microns; and

contacting exhaust gas from the engine with the catalyzed particulate trap.

13. The method of claim 12 further comprising coating an inlet side or an outlet side of the particulate trap with a washcoat comprising palladium, a support, and an oxygen storage component.

14. The method of claim 12 further comprising coating an inlet side or an outlet side of the particulate trap with a washcoat comprising rhodium, a support, and an oxygen storage component.

15. The method of claim 12 further comprising depositing the catalyst in an amount of no more than 2 g/in³ total on an inlet side and an outlet side.

16. The method of claim 15, wherein the catalyst is present in an amount in the range of 0.5 to 1.25 g/in³.

17. The method of claim 12 further comprising providing a second three-way conversion catalyst upstream of the catalyzed particulate trap.

18. The method of claim 12 further comprising contacting the catalyzed particulate trap during cold start conditions and bypassing the catalyzed particulate trap after cold start conditions.

19. An emission treatment system downstream of a gasoline direct injection engine for treatment of an exhaust system comprising hydrocarbons, carbon monoxide, nitrogen oxides, and particulates, the emission treatment system comprising a catalyzed particulate trap having an oxidation catalyst or a three-way conversion catalyst deposited thereon;

one or more gas sensors, an on-board diagnostic (OBD) system; and

further comprising a NOx trap, an SCR catalyst, or both located downstream of the catalyzed particulate trap.

20. A method of treating an exhaust gas comprising hydrocarbons, carbon monoxide, nitrogen oxides, and particulates, the method comprising:

locating an emissions treatment system downstream of a gasoline direct injection engine;

providing a catalyzed particulate trap that comprises a three-way conversion (TWC) catalyst deposited on a particulate trap in the emissions treatment system;

providing a second three-way conversion catalyst upstream of the catalyzed particulate trap; and

contacting exhaust gas from the engine with the catalyzed particulate trap.

21. The method of claim 20 further comprising contacting the catalyzed particulate trap during cold start conditions and bypassing the catalyzed particulate trap after cold start conditions.