Integrated LNT-TWC Catalyst

• US 20150266014A1
• Filed: 03/16/2015
• Published: 09/24/2015
• Est. Priority Date: 03/21/2014
• Status: Active Grant

• Current Assignee: BASF Corporation (BASF SE)
• Original Assignee: BASF Corporation (BASF SE)
• Inventors: Xue, Wen-Mei, Siani, Attilio, Hochmuth, John K., Kinne, Markus, Kielbassa, Stefan
• Granted Patent: US 9,744,529 B2
• Time in Patent Office: Days
• US Class Current: 1/1
• 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 2255/2042 Barium
• CPC Class Codes: B01D 2255/2047 Magnesium
• CPC Class Codes: B01D 2255/2065 Cerium
• CPC Class Codes: B01D 2255/20715 Zirconium
• CPC Class Codes: B01D 2255/2092 Aluminium
• CPC Class Codes: B01D 2255/407 Zr-Ce mixed oxides
• CPC Class Codes: B01D 2255/9022 Two layers
• CPC Class Codes: B01D 2255/908 O2-storage component incorporated in the catalyst
• CPC Class Codes: B01D 2255/91 NOx-storage component incorporated in the catalyst
• CPC Class Codes: B01D 2258/012 Diesel engines and lean burn gasoline engines
• 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 53/945 characterised by a specific catalyst
• CPC Class Codes: B01J 21/04 Alumina
• CPC Class Codes: B01J 21/066 Zirconium or hafnium; Oxides or hydroxides thereof
• CPC Class Codes: B01J 23/63 with rare earths or actinides
• CPC Class Codes: B01J 35/19 Catalysts containing parts with different compositions
• CPC Class Codes: B01J 35/30 characterised by their physical properties
• CPC Class Codes: B01J 35/56 : Foraminous structures having flow-through passages or channels, e.g. grids or three-dimensional monoliths
• CPC Class Codes: B01J 37/0244 : Coatings comprising several layers
• CPC Class Codes: B01J 37/0248 : Coatings comprising impregnated particles
• CPC Class Codes: F01N 2510/0684 : having more than one coating layer, e.g. multi-layered coatings
• CPC Class Codes: F01N 3/0842 : Nitrogen oxides
• CPC Class Codes: F01N 3/2828 : Ceramic multi-channel monoliths, e.g. honeycombs
• CPC Class Codes: Y02T 10/12 : Improving ICE efficiencies

Abstract

A layered catalyst composite for the treatment of exhaust gas emissions, effective to provide lean NO_x trap functionality and three-way conversion functionality is described. Layered catalyst composites can comprise catalytic material on a substrate, the catalytic material comprising at least two layers. The first layer comprising rare earth oxide-high surface area refractory metal oxide particles, an alkaline earth metal supported on the rare earth oxide-high surface area refractory metal oxide particles, and at least one first platinum group metal component supported on the rare earth oxide-high surface area refractory metal oxide particles. The second layer comprising a second platinum group metal component supported on a first oxygen storage component (OSC) and/or a first refractory metal oxide support and, optionally, a third platinum group metal supported on a second refractory metal oxide support or a second oxygen storage component.

Claims

1. A layered catalyst composite for an exhaust stream of an internal combustion engine, the layered catalyst composite comprising a catalytic material on a substrate, the catalytic material comprising at least two layers, wherein:

the first layer comprises rare earth oxide-high surface area refractory metal oxide particles, an alkaline earth metal supported on the rare earth oxide-high surface area refractory metal oxide particles, and at least one first platinum group metal component supported on the rare earth oxide-high surface area refractory metal oxide particles; and

the second layer comprises a second platinum group metal component supported on a first oxygen storage component (OSC) and/or a first refractory metal oxide support and, optionally, a third platinum group metal supported on a second refractory metal oxide support or a second oxygen storage component.

2. The layered catalyst composite of claim 1, wherein the catalyst is effective to provide both lean NO_x trap functionality and three-way conversion functionality.

3. The layered catalyst composite of claim 1, wherein the first layer is disposed on the substrate that comprises a flow-through monolith and the second layer is disposed on the first layer.

4. The layered catalyst composite of claim 1, wherein the second layer is disposed on the substrate that comprises a flow-through monolith and the first layer is disposed on the second layer.

5. The layered catalyst composite of claim 1, wherein the substrate comprises a wall-flow filter and the first layer is on an inlet set of passages and the second layer is on an outlet set of passages.

6. The layered catalyst composite of claim 1, wherein the substrate comprises a wall-flow filter and the first layer is on an outlet set of passages and the second layer is on an inlet set of passages.

7. The layered catalyst composite of claim 1 that is free of hydrocarbon trap material.

8. The layered catalyst composite of claim 1, wherein the rare earth oxide-high surface area refractory metal oxide particles have a ceria phase present in a weight percent of the particles in the range of about 20% to about 80% on an oxide basis.

9. The layered catalyst composite of claim 1, wherein the rare earth oxide-high surface area refractory metal oxide particles comprise ceria-alumina particles.

10. The layered catalyst composite of claim 9, wherein the ceria-alumina particles have a ceria phase present in a weight percent of the particles in the range of about 20% to about 80% on an oxide basis.

11. The layered catalyst composite of claim 9, wherein the ceria-alumina particles are substantially free of alkaline earth metal.

12. The layered catalyst composite of claim 1, wherein the first, second, and third platinum group metal components independently comprise platinum, palladium, and/or rhodium.

13. The layered catalyst composite of claim 1, wherein the first platinum group metal component comprises both palladium and platinum.

14. The layered catalyst composite of claim 1, wherein the first platinum group metal component comprises platinum.

15. The layered catalyst composite of claim 1, wherein the second platinum group metal component comprises palladium.

16. The layered catalyst composite of claim 1, wherein the third platinum group metal component comprises rhodium.

17. The layered catalyst composite of claim 1, wherein the first and second refractory metal oxide supports independently comprise a compound that is activated, stabilized, or both selected from the group consisting of alumina, zirconia, alumina-zirconia, lanthana-alumina, lanthana-zirconia-alumina, baria-alumina, baria-lanthana-alumina, baria-lanthana-neodymia-alumina, alumina-chromia, alumina-ceria, and combinations thereof.

18. The layered catalyst composite of claim 1, wherein the first and second oxygen storage components comprise a ceria-zirconia composite or a rare earth-stabilized ceria-zirconia.

19. The layered catalyst composite of claim 1, wherein the first oxygen storage component and the second oxygen storage component comprise different ceria-zirconia composites, the first oxygen storage component comprising ceria in the range of 35 to 45% by weight and zirconia in the range of 43 to 53% by weight and the second oxygen storage component comprising ceria in the range of 15 to 25% by weight and zirconia in the range of 70 to 80% by weight.

20. The layered catalyst composite of claim 1, wherein the alkaline earth metal comprises barium.

21. The layered catalyst composite of claim 20, wherein the barium is present in an amount in the range of about 5% to 30% by weight on an oxide basis of the first layer.

22. The layered catalyst composite of claim 1, wherein the second layer further comprises a second alkaline earth metal supported on the first refractory metal oxide support.

23. The layered catalyst composite of claim 20, wherein the second alkaline earth metal comprises barium.

24. The layered catalyst composite of claim 21, wherein the barium is present in an amount in the range of about 0% to about 10% by weight on an oxide basis of the second layer.

25. The layered catalyst composite of claim 1, wherein under lean conditions, the layered catalyst composite is effective to simultaneously store NO_x, and to oxidize CO, HC, and NO to NO_x.

26. The layered catalyst composite of claim 1, wherein under rich conditions, the layered catalyst composite is effective to simultaneously convert CO and HC and to release and reduce NO_x.

27. The layered catalyst composite of claim 1, wherein under stoichiometric conditions, the layer catalyst composite is effective to simultaneously convert CO, HC, and NO_x.

28. The layered catalyst composite of claim 1, wherein

the catalyst composite is effective to provide both lean NO_x trap functionality and three-way conversion functionality;

the substrate comprises a flow-through carrier and the first layer is disposed on the substrate and the second layer is disposed on the first layer;

the rare earth oxide-high surface area refractory metal oxide particles comprise ceria-alumina particles having a ceria phase present in a weight percent of the composite in the range of about 20% to about 80% on an oxide basis;

the first platinum group metal component comprises palladium and/or platinum;

the second platinum group metal component comprises palladium; and

the third platinum group metal component comprises rhodium.

29. An exhaust gas treatment system comprising the layered catalyst composite of claim 1 located downstream of an engine.

30. The exhaust gas treatment system of claim 29, wherein the engine comprises a lean burn engine.

31. The exhaust gas treatment system of claim 30, wherein the lean burn engine comprises a lean gasoline direct injection engine.

32. The exhaust gas treatment system of claim 29, further comprising a catalyst selected from the group consisting of TWC, GPF, SCR, LNT, AMOx, SCR on a filter, and combinations thereof.

33. The exhaust gas treatment system of claim 32, wherein the catalyst is an SCR catalyst located downstream of the layered catalyst composite.

34. A method for treating a gas comprising hydrocarbons, carbon monoxide, and nitrogen oxides comprising:

contacting the gas with the layered catalyst composite of claim 1, wherein;

under lean conditions, the layered catalyst composite is effective to simultaneously store NO_x, and to oxidize CO, HC, and NO;

under rich conditions, the layered catalyst composite is effective to simultaneously convert CO and HC and to release and reduce NO_x; and

under stoichiometric conditions, the layered catalyst composite is effective to simultaneously convert CO, HC, and NO_x.

35. A method of making a layered catalyst composite, the method comprising providing a carrier and coating the carrier with first and second layers of catalytic material;

the first layer comprising rare earth oxide-high surface area refractory metal oxide particles, an alkaline earth metal supported on the rare earth oxide-high surface area refractory metal oxide particles, and at least one first platinum group metal component supported on the rare earth oxide-high surface area refractory metal oxide particles, the second layer being the outermost layer of the composite, comprising a second platinum group metal component supported on a first oxygen storage component (OSC) or a first refractory metal oxide support and a third platinum group metal component supported on a second refractory metal oxide support or a second oxygen storage component.