Nitrous oxide removal catalysts for exhaust systems

Patent metadata

Field	Value
Publication number	US-10634030-B2
Application number	US-201515532751-A
Country	US
Kind code	B2
Filing date	Dec 8, 2015
Priority date	Dec 8, 2014
Publication date	Apr 28, 2020
Grant date	Apr 28, 2020

Abstract

A nitrous oxide (N 2 O) removal catalyst composite is provided, comprising a N 2 O removal catalytic material on a substrate, the catalytic material comprising a rhodium (Rh) component supported on a ceria-based support, wherein the catalyst composite has a H 2 -consumption peak of about 100° C. or less as measured by hydrogen temperature-programmed reduction (H 2 -TPR). Methods of making and using the same are also provided.

First claim

What is claimed:

1. A nitrous oxide (N 2 O) removal catalyst composite for an exhaust stream of an internal combustion engine comprising: a N 2 O removal catalytic material on a substrate, the catalytic material comprising a rhodium (Rh) component supported on a ceria-based support, wherein the catalytic material has a H 2 -consumption peak of about 100° C. or less as measured by hydrogen temperature-programmed reduction (H 2 -TPR) and is effective to decompose at least a portion of nitrous oxide (N 2 O) in the exhaust stream to nitrogen (N 2 ) and oxygen (O 2 ) or to reduce at least a portion of the N 2 O to N 2 and water, N 2 and carbon dioxide (CO 2 ), or N 2 , water, and CO 2 under conditions of the exhaust stream, and
wherein the ceria-based support comprises ceria in an amount in the range of about 56 to about 100% by weight of the support on an oxide basis.

2. The N 2 O removal catalyst composite of claim 1 , wherein the H 2 -consumption peak after aging at 750° C. for 20 hours with 10 volume % water in air occurs at a lower temperature than the temperature of the H 2 -consumption peak of fresh catalytic material.

3. The N 2 O removal catalyst composite of claim 1 , wherein N 2 O removal activity of the catalytic material after aging at 750° C. for 20 hours with 10 volume % water is higher than N 2 O removal activity of fresh catalytic material.

4. The N 2 O removal catalyst composite of claim 1 , wherein the ceria-based support maintains about 90 to about 100% of its pore volume after aging at 750° C. for 20 hours with 10 weight % water in air.

5. The N 2 O removal catalyst composite of claim 1 , wherein the ceria-based support comprises about 90 to about 100 weight % CeO 2 and has a pore volume that is at least about 0.20 cm 3 /g.

6. The N 2 O removal catalyst composite of claim 1 , wherein the ceria-based support comprises a fresh surface area that is in the range of about 40 to about 200 m 2 /g.

7. The N 2 O removal catalyst composite of claim 1 , wherein the ceria-based support comprises a surface area that is in the range of about 20 to about 140 m 2 /g after aging at 750° C. for 20 hours with 10 weight % water in air.

8. The N 2 O removal catalyst composite of claim 1 , wherein the ceria has a crystallite size in the range of about 3 to about 20 nm measured by x-ray diffraction (XRD).

9. The N 2 O removal catalyst composite of claim 1 , wherein the ceria-based support comprise: an x-ray diffraction crystallite size ratio of aged material to fresh material of about 2.5 or less, where aging is at 750° C. for 20 hours with 10% H 2 O in air.

10. The N 2 O removal catalyst composite of claim 1 , wherein the ceria-based support further comprises a promoter comprising yttria, samaria, gadolinia, zirconia, or silica.

11. The N 2 O removal catalyst composite of claim 1 , wherein the rhodium component is present on the support in an amount in the range of about 0.01 to about 5% by weight of the support.

12. The N 2 O removal catalyst composite of claim 1 , wherein the rhodium component is present in an amount of about 0.04 to about 3% by weight of the support.

13. The N 2 O removal catalyst composite of claim 1 , wherein the rhodium component has a crystallite size of less than about 5 nm.

14. The N 2 O removal catalyst composite of claim 1 , wherein the rhodium component is loaded on the substrate in an amount in the range of about 1 to about 105 g/ft 3 .

15. The N 2 O removal catalyst composite of claim 1 , wherein the catalytic material further comprises an additional metal component.

16. The N 2 O removal catalyst composite of claim 15 , wherein the additional metal component comprises platinum (Pt), palladium (Pd), silver (Au), copper (Cu), or combinations thereof.

17. The N 2 O removal catalyst composite of claim 15 , wherein the catalytic material further comprises a metal oxide for promoting the Rh and/or additional metal component.

18. The N 2 O removal catalyst composite of claim 17 , wherein the metal oxide comprises ceria, praseodymia, yttria, samaria, or gadolinia.

19. The N 2 O removal catalyst composite of claim 1 , wherein the substrate comprises a monolithic substrate.

20. The N 2 O removal catalyst composite of claim 1 , wherein the substrate comprises a wall-flow filter.

21. The N 2 O removal catalyst composite of claim 1 for an exhaust stream of an internal combustion engine comprising: a N 2 O removal catalytic material in a washcoat on a substrate, the catalytic material comprising a rhodium (Rh) component supported on a ceria-based support and is effective to convert nitrous oxide (N 2 O) under conditions of the exhaust stream, wherein the ceria-based support comprises:
about 90 to about 100 weight % CeO 2 ;
a pore volume that is in the range of about 0.20 to about 0.40 cm 3 /g;
a fresh surface area that is in the range of about 40 to about 200 m 2 /g; and
an aged surface area that is in the range of about 20 to about 140 m 2 /g after aging at 750° C. for 20 hours with 10 weight % water in air.

22. An emissions treatment system for treatment of an internal combustion engine exhaust stream including hydrocarbons, carbon monoxide, and nitrogen oxides, the emission treatment system comprising:
an exhaust conduit in fluid communication with the internal combustion engine via an exhaust manifold;
a treatment catalyst; and
the N 2 O removal catalyst composite of claim 1 .

23. The emissions treatment system of claim 22 , wherein the treatment catalyst comprises a precious metal on a high surface area refractory metal oxide support that is effective to oxidize hydrocarbons and/or carbon monoxide under conditions of the exhaust stream.

24. The emissions treatment system of claim 23 , wherein the treatment catalyst comprises a nitrogen oxides treatment catalyst selected from the group consisting of a three-way conversion (TWC) catalyst, a lean NOx trap (LNT), and a Selective Catalytic Reduction (SCR) catalyst.

25. The emissions treatment system of claim 24 , wherein the N 2 O removal catalyst composite is located downstream of the nitrogen oxides treatment catalyst.

26. The emissions treatment system of claim 24 , wherein the system is zoned and the nitrogen oxides treatment catalyst is in a front, upstream zone and the N 2 O removal catalyst composite is in a back, downstream zone.

27. The emissions treatment system of claim 24 , wherein the system is layered and the nitrogen oxides treatment catalyst is in an outer layer and the N 2 O removal catalytic material of the catalyst composite is in an inner layer.

28. The emissions treatment system of claim 24 , wherein the system is layered and the nitrogen oxides treatment catalyst is in an inner layer and the N 2 O removal catalytic material of the N 2 O catalyst composite is in an outer layer.

29. A method for treating exhaust gases comprising contacting a gaseous stream comprising hydrocarbons, carbon monoxide, and nitrogen oxides with the N 2 O removal catalyst composite of claim 1 .

30. The method of claim 29 , wherein N 2 O removal activity of the catalytic material after aging at 750° C. for 20 hours with 10 weight % water is higher than N 2 O removal activity of fresh catalytic material.

Assignees

• Basf Corp

Inventors

• Li Yuejin
• Zheng Xiaolai
• Roth Stanley
• Gerlach Olga
• Sundermann Andreas

Classifications

• B01D2255/9205

  Porosity · CPC title

• B01J37/0215

  Coating · CPC title

• B01J23/46

  Ruthenium, rhodium, osmium or iridium · CPC title

• B01J37/0248

  Coatings comprising impregnated particles · CPC title

• B01D2255/2065

  Cerium · CPC title