Catalyzed filter for treating exhaust gas

Patent metadata

Field	Value
Publication number	US-9687785-B2
Application number	US-201414292056-A
Country	US
Kind code	B2
Filing date	May 30, 2014
Priority date	May 31, 2013
Publication date	Jun 27, 2017
Grant date	Jun 27, 2017

Abstract

Provided is a diesel particulate filter capable of removing soot from an exhaust gas while operating at low backpressure, the filter comprising (a) a wall-flow filter substrate having a mean pore size, an inlet side, an outlet side, and a porous interior between the inlet and outlet sides; and (b) a catalyst composition coated from the outlet side of the substrate, wherein the catalyst composition has a d 50 particle size distribution, wherein the d 50 particle size distribution is greater than or equal to the mean pore size divided by 4.9, and wherein the inlet side is substantially free of a catalyst coating.

First claim

The invention claimed is:

1. A diesel particulate filter comprising:
a. a wall-flow filter substrate having a mean pore size, an inlet side, an outlet side having an outlet surface, and a porous interior between the inlet and outlet sides; and
b. a catalyst composition having a d 50 particle size distribution, said d 50 particle size distribution of the catalyst composition being greater than or equal to the mean pore size of the substrate divided by 4.9, where the mean pore size of the substrate is about 12 μm to about 20 μm and at least about 50% of the pores are within this range based on the total pore volume and/or total number of pores;
where the catalyst composition is a coating on the surface of the outlet side and the composition has a concentration gradient between the outlet surface of the filter and the inlet side of the filter, wherein the concentration is greatest towards the outlet surface, the inlet side of the substrate is substantially free of a catalyst coating, and
the diesel particulate filter provides a backpressure after exposure to soot that is less than the backpressure on a filter having the same catalyst composition on: (1) the inlet side only or (2) on both the inlet and outlet sides where half of the catalyst coating was applied to the inlet side of the filter and half of the catalyst coating was applied to the outlet side of the filter.

2. The diesel particulate filter of claim 1 , wherein the mean pore size is at least about 15 μm.

3. The diesel particulate filter of claim 1 , wherein the wall-flow filter substrate further comprises a porosity of at least about 45 percent.

4. The diesel particulate filter of claim 1 , wherein the wall-flow filter substrate further comprises a porosity of at least about 55 percent.

5. The diesel particulate filter of claim 1 , wherein the wall-flow filter substrate further comprises a porosity of at least about 65 percent.

6. The diesel particulate filter of claim 1 , wherein said d 50 particle size distribution is at least about 2.5 microns.

7. The diesel particulate filter of claim 1 , wherein said d 50 particle size distribution is at least about 3.5 microns.

8. The diesel particulate filter of claim 1 , wherein said d 50 particle size distribution is at least about 4 microns.

9. The diesel particulate filter of claim 1 , wherein the porous interior is substantially free of a catalyst coating.

10. The diesel particulate filter of claim 1 , wherein the catalyst composition is present in an amount of about 0.5-3.0 g/in 3 .

11. The diesel particulate filter of claim 1 , wherein the catalyst composition is present in an amount of about 0.9-1.8 g/in 3 .

12. The diesel particulate filter of claim 1 , wherein the catalyst composition is present as a single layer.

13. The diesel particulate filter of claim 1 , wherein the catalyst composition is present on the outlet side of the filter as two or more layers.

14. The diesel particulate filter of claim 1 , wherein the catalyst composition comprises a selective reduction catalyst.

15. The diesel particulate filter of claim 14 , wherein said selective reduction catalyst comprises Cu or Fe on and/or within a small pore molecular sieve.

16. The diesel particulate filter of claim 1 , wherein the catalyst composition comprises an ammonia slip catalyst.

17. The diesel particulate filter of claim 1 , the catalyst composition having a d 10 particle size distribution of one or more of at least 0.75 μm, at least about 1 μm, about 1 to about 1.5 μm, about 1 to about 2 μm, about 1 μm, about 2 μm, or about 3 μm.

18. The diesel particulate filter of claim 1 , the catalyst composition having a d 10 particle size distribution and a d 90 particle size distribution, where the catalyst composition has:
a. a d 10 particle size distribution of about 1 to about 1.5 μm, a d 50 particle size distribution of about 3.75 to about 4.5 μm, and a d 90 particle size distribution of about 7.5 to about 9 μm, or
b. a d 10 particle size distribution of about 1.5 to about 2 μm, a d 50 particle size distribution of about 3.5 to about 4 μm, and a d 90 particle size distribution of about 7 to about 8 μm.

19. The diesel particulate filter of claim 1 , wherein at least about 75% of the pores are a mean pore size of the 12 μm to about 20 μm.

20. The diesel particulate filter of claim 1 , the catalyst composition having a d 10 particle size distribution and a d 90 particle size distribution, where the catalyst composition has:
(a) a d 10 particle size distribution of at least 0.75 μm, at least about 1 μm, about 1 to about 2 μm, about 1 to about 1.5 μm, 1 μm, 2 μm, or 3 μm, and
(b) a d 90 particle size distribution of one or more of less than about 15 μm, less than about 10 μm, 8 μm, 7 μm, or 6 μm.

21. A system for treating a lean-burn exhaust gas comprising:
a. a diesel particulate filter according to claim 1 ; and
b. at least one exhaust system component in fluid communication with the diesel particulate filter, wherein the exhaust system component is selected from the group consisting of a source of NO 2 disposed upstream of the diesel particulate filter, a source of reductant disposed upstream of the diesel particulate filter, an AMOX catalyst, a NOx trap, a NOx absorber catalyst, a diesel oxidation catalyst, and an SCR catalyst.

22. A method for reducing soot in a lean burn exhaust gas comprising:
a. contacting an exhaust gas stream carrying soot and optionally containing NO x , with a diesel particulate filter according to claim 1 ;
b. trapping at least a portion of the soot on and/or in the diesel particulate filter while allowing the exhaust gas to pass through the diesel particulate filter; and
c. periodically and/or continuously burning the trapped soot to regenerate the filter.

23. The method of claim 22 further comprising the step of:
contacting the exhaust gas with a SCR catalyst coated from the outlet side of the filter to reduce the concentration of NOx in exhaust gas.

Assignees

• Johnson Matthey Plc

Inventors

• Chen Hai-Ying
• De Debnath
• Manning Wendy
• Cox Julian Peter

Classifications

• Y02T10/12

  Improving ICE efficiencies · CPC title

• Y02T10/24

  Cross-Sectional Technologies · mapped topic

• F01N2510/0682

  having a discontinuous, uneven or partially overlapping coating of catalytic material, e.g. higher amount of material upstream than downstream or vice versa · CPC title

• F01N3/035 Primary

  with catalytic reactors · CPC title

• B01D53/9472 Primary

  in different zones · CPC title