Partial filter substrates containing SCR catalysts and methods and emissions treatment systems

Patent metadata

Field	Value
Publication number	US-9475002-B2
Application number	US-76544110-A
Country	US
Kind code	B2
Filing date	Apr 22, 2010
Priority date	Apr 22, 2009
Publication date	Oct 25, 2016
Grant date	Oct 25, 2016

Abstract

Catalytic articles, methods and emissions treatment systems for treating an engine exhaust gas stream containing NO x and particulate matter are disclosed and include a particulate filter comprising a first SCR catalyst for NO x conversion disposed downstream of the injector. The particulate filter is a partial filter with a particle filtration efficiency between about 30% and 60% and an SCR catalyst loading in the range of 0.1 g/in 3 -3.5 g/in 3 .

First claim

The invention claimed is:

1. A catalytic article for use in a system for treating an engine exhaust gas stream containing an initial NO x concentration and particulate matter, the gas stream producing a system back pressure and a system NO x conversion, the catalytic article comprising:
a particulate filter comprising a first SCR catalyst effective for NO x conversion, the particulate filter having a particle filtration efficiency in the range of about 30% to 60% by mass and having a catalyst loading in the range of about 0.5 g/in 3 and 3.5 g/in 3 , wherein the particulate filter comprises a foam having an open or reticulated structure comprising cells and struts forming cellular walls, the foam defining a tortuous flow path for the engine exhaust gas stream and having a porosity between 50% and 95%.

2. The catalytic article of claim 1 , wherein the particulate filter has an axial length and the SCR catalyst is disposed on a zone extending less than the full axial length of the filter.

3. The catalytic article of claim 1 , wherein the SCR catalyst comprises a zeolite having a CHA structure.

4. The catalytic article of claim 1 , wherein the SCR catalyst comprises a molecular sieve containing at least one of Cu, Fe, Mn, Co, Ag and combinations thereof.

5. The catalytic article of claim 1 , wherein the particulate filter comprises a metal foam.

6. The catalytic article of claim 1 , wherein the SCR catalyst loading is in the range of about 0.5 g/in 3 to 2.0 g/in 3 .

7. A diesel engine emissions treatment system comprising the catalytic article of claim 1 downstream from an engine, and further comprising an oxidation catalyst disposed upstream of the particulate filter.

8. The emissions treatment system of claim 7 , wherein there is no intervening SCR catalyst disposed between the engine and the particulate filter.

9. The emissions treatment system of claim 7 , wherein the first SCR catalyst provides a NO x conversion of at least about 10% at 250° C. and a space velocity of about 40,000 h −1 when tested in a gas stream that comprises about 500 ppm NO, about 500 ppm NH 3 and about 5% water in air.

10. An emissions treatment system comprising the catalytic article of claim 1 , and a flow through substrate loaded with a second SCR catalyst effective for NO x conversion disposed downstream of the particulate filter, wherein conversion of NO x by the particulate filter is in the range of about 10% to 100% of the system total NO x conversion.

11. The emissions treatment system of claim 10 , further comprising an oxidation catalyst disposed upstream of the particulate filter.

12. The emissions treatment system of claim 10 , wherein the first SCR catalyst provides a NO conversion of at least about 10% at 250° C. and a space velocity of about 40,000 h −1 when tested in a gas stream that comprises about 500 ppm NO, about 500 ppm NH 3 and about 5% water in air.

13. The catalytic article of claim 1 , wherein the foam has a porosity between 60% and 95%.

14. The catalytic article of claim 1 , wherein the cells have a mean cell diameter in the range of 0.5 to 5 mm.

15. The catalytic article of claim 1 , wherein the foam has a pores per inch ranging from 3 to 100.

16. The catalytic article of claim 1 , wherein the foam has a pores per inch ranging from 30 to 90.

17. The catalytic article of claim 1 , wherein the foam has a pores per inch ranging from 40 to 70.

18. The catalytic article of claim 5 , wherein the metal foam comprises a metal selected from the group consisting of iron, titanium, tantalum, tungsten, noble metals, copper, nickel, bronze, aluminum, zirconium, and combinations and alloys thereof.

19. A method of treating an engine exhaust gas stream containing an initial NO x concentration and effective for conversion of NO x , the gas stream having a system back pressure and a system NO x conversion, the method comprising:
passing the engine exhaust gas stream produced by an engine through the catalytic article of claim 1 .

20. The method of treating an engine exhaust gas stream of claim 19 , wherein there is no intervening SCR catalyst disposed between the engine and the catalytic article.

21. The method of treating an engine exhaust gas stream of claim 19 , wherein a gas stream having an intermediate NO x concentration is produced by the catalyst article, the method further comprising:
injecting ammonia or an ammonia precursor into the exhaust gas system upstream of the catalyst article; and
passing the gas stream having the intermediate NO x concentration through a second substrate loaded with a second SCR catalyst disposed downstream of the catalyst article.

22. The method of treating an engine exhaust gas stream of claim 21 , wherein there is no intervening SCR catalyst disposed between the engine and the particulate filter.

Assignees

• Boorse R Samuel
• Voss Kenneth E
• Dieterle Martin
• Basf Corp

Inventors

• Boorse R Samuel
• Voss Kenneth E
• Dieterle Martin

Classifications

• F01N3/035 Primary

  with catalytic reactors · CPC title

• F01N3/022

  characterised by specially adapted filtering structure, e.g. honeycomb, mesh or fibrous · CPC title

• B01D2257/404

  Nitrogen oxides other than dinitrogen oxide · CPC title

• B01D53/94

  by catalytic processes · CPC title

• B01D2255/20738

  Iron · CPC title