Thermal stability of copper-manganese spinel as Zero PGM catalyst for TWC application

• US 9,731,279 B2
• Filed: 10/30/2014
• Issued: 08/15/2017
• Est. Priority Date: 10/30/2014
• Status: Expired due to Fees

• Current Assignee: Clean Diesel Technologies, Inc.
• Original Assignee: Clean Diesel Technologies, Inc.
• Inventors: Abken, Anke Elizabeth, Nazarpoor, Zahra, Golden, Stephen J.
• Primary Examiner(s): Zimmer, Anthony J
• Application Number:
  US14/528,746
• Publication Number:
  US 20160121308A1
• Time in Patent Office: 1,020 Days
• CPC Class Codes: B01D 2255/20715 Zirconium
• CPC Class Codes: B01D 2255/2073 Manganese
• CPC Class Codes: B01D 2255/20746 Cobalt
• CPC Class Codes: B01D 2255/20761 Copper
• CPC Class Codes: B01D 2255/2092 Aluminium
• CPC Class Codes: B01D 2255/405 Spinels
• CPC Class Codes: B01D 2255/65 Catalysts not containing noble metals
• CPC Class Codes: B01D 53/945 characterised by a specific catalyst
• CPC Class Codes: B01J 23/005 Spinels
• CPC Class Codes: B01J 23/8892 Manganese
• CPC Class Codes: B01J 2523/00 Constitutive chemical elements of heterogeneous catalysts
• CPC Class Codes: B01J 2523/17 Copper
• CPC Class Codes: B01J 2523/31 Aluminium
• CPC Class Codes: B01J 2523/3718 Praseodymium
• CPC Class Codes: B01J 2523/48 Zirconium
• CPC Class Codes: B01J 2523/72 Manganese
• CPC Class Codes: B01J 2523/845 Cobalt
• CPC Class Codes: B01J 37/0242 Coating followed by impregnation
• CPC Class Codes: B01J 37/0244 Coatings comprising several layers
• CPC Class Codes: Y02T 10/12 Improving ICE efficiencies

Abstract

Effect of the type of ZPGM material composition to improve thermal stability of ZPGM catalyst systems for TWC application is disclosed. ZPGM catalyst system samples are prepared and configured with washcoat on ceramic substrate, overcoat including doped Zirconia support oxide, and impregnation layer including either Cu₁Mn₂O₄ spinel or Cu₁Co₁Mn₁O₄ spinel. Testing of ZPGM catalyst samples including variations of aging temperatures and different impregnation layer materials are developed under isothermal steady state sweep test condition for ZPGM catalyst systems to evaluate performance especially NO_x conversions and level of thermal stability. As a result disclosed ZPGM catalyst systems with most suitable spinel that includes Cu₁Co₁Mn₁O₄ in impregnation layer exhibit high NOx conversion and significant improved thermal stability compare to Cu₁Mn₂O₄ spinel, which is suitable for under floor and close coupled TWC application. The effect of adding Co to Cu—Mn spinel composition to improve thermal stability confirmed by TPR measurement.

Claims

1. A zero platinum group metal (ZPGM) catalyst system comprising:

a substrate,

a washcoat layer overlying the substrate,

an overcoat layer overlying the washcoat layer, said overcoat layer consisting of ZrO₂—

Pr₆O₁₁, and

an impregnation layer deposited on a surface of the overcoat layer;

wherein the impregnation layer comprises a spinel according to the formula Cu_xMn_3-xO₄ or Cu_xCo_yMn_3-x-yO₄, wherein X and Y are each independently 0.01 to 1.0, wherein the catalyst system has been aged at about 850°

C.

2. The ZPGM catalyst system of claim 1, wherein the substrate is ceramic.

3. The ZPGM catalyst system of claim 1, wherein the impregnation layer comprises CuMn₂O₄ spinel.

4. The ZPGM catalyst system of claim 1, wherein the impregnation layer comprises CuCoMnO₄ spinel.

5. The ZPGM catalyst system of claim 4, wherein the spinel is stable up to about 1040°

C.

6. The ZPGM catalyst system of claim 1, wherein the washcoat layer is an alumina-based washcoat on substrate.

7. The ZPGM catalyst system of claim 1, wherein the spinel is aged under fuel cut gas conditions.

8. The ZPGM catalyst system of claim 1, wherein nitrogen oxide (NOx) conversion is about 52% to about 98% when having an R-value of 1.2 under an isothermal steady state sweep condition.

9. A method of producing an aged zero platinum group metal (ZPGM) catalyst system comprising aging the catalyst system of claim 1 at a temperature of about 850°

C.

10. The method of claim 9, wherein the aging lasts about 20 hours.

11. The method of claim 9, wherein the impregnation layer comprises CuMn₂O₄ spinel.

12. The method of claim 9, wherein the impregnation layer comprises CuCoMnO₄ spinel.

13. The method of claim 12, wherein the aged ZPGM catalyst system converts nitrogen oxide (NOx) at about 52% to about 98% when having an R-value of 1.2 under an isothermal steady state sweep condition.