NOX STORAGE CATALYST WITH IMPROVED HYDROCARBON CONVERSION ACTIVITY

• US 20110305612A1
• Filed: 06/09/2011
• Published: 12/15/2011
• Est. Priority Date: 06/10/2010
• Status: Active Grant

• Current Assignee: BASF SE
• Original Assignee: BASF SE
• Inventors: Stiebels, Susanne, Neubauer, Torsten, Müller-Stach, Torsten, Schneider, Edith
• Granted Patent: US 8,734,743 B2
• Time in Patent Office: Days
• US Class Current: 423/212
• 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 2255/502 Beta zeolites
• CPC Class Codes: B01D 2255/9022 Two layers
• CPC Class Codes: B01D 2255/9025 Three layers
• CPC Class Codes: B01D 2255/91 NOx-storage component incorporated in the catalyst
• CPC Class Codes: B01D 2255/912 HC-storage component incorporated in the catalyst
• CPC Class Codes: B01D 2258/012 Diesel engines and lean burn gasoline engines
• CPC Class Codes: B01D 53/945 characterised by a specific catalyst
• CPC Class Codes: B01J 23/58 with alkali- or alkaline earth metals
• CPC Class Codes: B01J 23/63 with rare earths or actinides
• CPC Class Codes: B01J 29/061 containing metallic elements added to the zeolite
• CPC Class Codes: B01J 29/7415 Zeolite Beta
• CPC Class Codes: B01J 37/0244 Coatings comprising several layers
• CPC Class Codes: B01J 37/0246 : Coatings comprising a zeolite
• CPC Class Codes: F01N 2510/0684 : having more than one coating layer, e.g. multi-layered coatings
• CPC Class Codes: F01N 3/0814 : combined with catalytic converters, e.g. NOx absorption/storage reduction catalysts
• 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

Described is a nitrogen oxide storage catalyst comprising:

• • a substrate;
  • a first washcoat layer provided on the substrate, the first washcoat layer comprising a nitrogen oxide storage material,
  • a second washcoat layer provided on the first washcoat layer, the second washcoat layer comprising a hydrocarbon trap material,
    wherein the hydrocarbon trap material comprises substantially no element or compound in a state in which it is capable of catalyzing selective catalytic reduction, preferably wherein the hydrocarbon trap material comprises substantially no element or compound in a state in which it is capable of catalyzing a reaction wherein nitrogen oxide is reduced to N₂,
    said catalyst further comprising a nitrogen oxide conversion material which is either comprised in the second washcoat layer and/or in a washcoat layer provided between the first washcoat layer and the second washcoat layer.

Claims

1. A nitrogen oxide storage catalyst comprising:

a substrate;

a first washcoat layer provided on the subtstrate, the first washcoat layer comprising a nitrogen oxide storage material,

a second washcoat layer provided on the first washcoat layer, the second washcoat layer comprising a hydrocarbon trap material,

wherein the hydrocarbon trap material comprises substantially no element or compound in a state in which it is capable of catalyzing selective catalytic reduction,

said catalyst further comprising a nitrogen oxide conversion material which is either comprised in the second washcoat layer and/or in a washcoat layer provided between the first washcoat layer and the second washcoat layer.

2. The nitrogen oxide storage catalyst according to claim 1, wherein the hydrocarbon trap material comprises substantially no element or compound in a state in which it is capable of catalyzing a reaction wherein nitrogen oxide is reduced to N₂.

3. The nitrogen oxide storage catalyst according to claim 1, wherein the first washcoat layer further comprises an oxygen storage component.

4. The nitrogen oxide storage catalyst according to claim 1, wherein the first washcoat layer further comprises at least one platinum group metal.

5. The nitrogen oxide storage catalyst according to claim 4, wherein the first washcoat layer further comprises metal oxide support particles.

6. The nitrogen oxide storage catalyst according to claim 1, wherein the nitrogen oxide storage material comprises at least one metal compound selected from the group consisting of alkali metal compounds, alkaline earth metal compounds, rare earth metal compounds, and mixtures thereof.

7. The nitrogen oxide storage catalyst according to claim 6, wherein the nitrogen oxide storage material comprises at least one element selected from the group consisting of Li, Na, K, Rb, Cs, Mg, Ca, Sr, Ba, Ce, La, Pr, Nd, and mixtures thereof.

8. The nitrogen oxide storage catalyst according to claim 1, wherein the nitrogen oxide conversion material comprises an oxygen storage component.

9. The nitrogen oxide storage catalyst according to claim 1, wherein the nitrogen oxide conversion material comprises at least one platinum group metal.

10. The nitrogen oxide storage catalyst according to claim 9, wherein the nitrogen oxide conversion material further comprises metal oxide support particles.

11. The nitrogen oxide storage catalyst according to claim 10, wherein in the nitrogen oxide conversion material, Rh is supported on other metal oxide support particles than Pt and/or Pd.

12. The nitrogen oxide storage catalyst according to claim 1, wherein Pt and Pd are supported on the same metal oxide support particles, wherein said metal oxide particles comprise alumina.

13. The nitrogen oxide storage catalyst according to claim 1, wherein the one or more washcoat layers comprising a nitrogen oxide conversion material contain substantially no Mg and no Ba.

14. The nitrogen oxide storage catalyst according to claim 1, wherein the hydrocarbon trap material comprises a zeolite.

15. The nitrogen oxide storage catalyst according to claim 1, wherein the hydrocarbon trap material further comprises Pt and/or Pd.

16. The nitrogen oxide storage catalyst according to claim 1, wherein the hydrocarbon trap material comprises substantially no Cu, Co, Mn, Ag, In, Ir, and/or Rh.

17. The nitrogen oxide storage catalyst according to claim 1, wherein the substrate is a monolith.

18. A treatment system for an automobile exhaust gas stream comprising

a combustion engine,

an exhaust gas conduit in fluid communication with the engine, and

a nitrogen oxide storage catalyst according to claim 1 provided within the exhaust gas conduit.

19. A method for the treatment of automobile engine exhaust gas comprising:

(i) providing a nitrogen oxide storage catalyst according to claim 1, and

(ii) conducting an automobile engine exhaust gas stream over and/or through the nitrogen oxide storage catalyst.

20. The method according to claim 19, wherein the automobile engine exhaust gas stream is from a lean burn combustion engine.