Processing

Please wait...

Settings

Settings

Goto Application

1. WO2010124105 - PARTIAL FILTER SUBSTRATES CONTAINING SCR CATALYSTS AND EMISSION TREATMENT SYSTEMS AND METHODS OF TREATING ENGINE EXHAUST

Note: Text based on automatic Optical Character Recognition processes. Please use the PDF version for legal matters

[ EN ]

Claims:

1. A catalytic article for use in a system for treating an engine exhaust gas stream containing an initial NOx concentration and particulate matter, the gas stream producing a system back pressure and a system NOx conversion, the catalyst composite comprising: a particulate filter comprising a first SCR catalyst effective for NOx conversion, the particulate filter having a particle filtration efficiency in the range of about 30% and 60% by mass and having a catalyst loading in the range of about 0.1 g/in and 3.5 g/in .

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 particulate filter comprises a foam having an open or reticulated substrate structure and the foam comprises pores and struts providing cellular walls.

4. The catalytic article of claim 1, wherein the SCR catalyst loading is in the range of about 0.5 g/in3 and 2.0 g/in3.

5. A diesel engine emissions treatment system comprising the catalytic article of claim 1, and further comprising an oxidation catalyst disposed upstream of the particulate filter and there is no intervening SCR catalyst disposed between the engine and the particulate filter.

6. The emissions treatment system of claim 5, wherein the target system NOx conversion is more than about 30% and the maximum targeted percentage increase in system back pressure is about 25% compared to an identical system with an identical uncoated filter.

7. The emissions treatment system of claim 6, wherein the first SCR catalyst comprises any material that provides a NOx conversion of at least about 10% at 250 0C 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 NH3 and about 5% water in air.

8. An emissions treatment system comprising the catalytic article of claim 1, and a flow through substrate loaded with a second SCR catalyst effective for NOx conversion disposed downstream of the particulate filter, wherein the system N0χ conversion is in the range of about 50% and 100%.

9. The emissions treatment system of claim 8, further comprising an oxidation catalyst disposed upstream of the particulate filter.

10. The emissions treatment system of claim 8, wherein the treatment system is operative to generate an intermediate NOx concentration after the gas stream passes through the particulate filter and a final NOx concentration after the gas stream passes through a second substrate, and wherein the system NOx conversion based on the initial NOx concentration and the final NOx concentration and an increase in system back pressure lies within an operational window based on a minimum targeted system NOx conversion and a maximum targeted percentage increase in system back pressure.

11. A method of treating an engine exhaust gas stream containing an initial NOx concentration and effective for conversion of NOx, the gas stream having a system back pressure and a system NOx conversion, the method comprising: defining an exhaust gas system operational window based on a minimum targeted system NOx conversion and a maximum targeted percentage increase in system back pressure, the percentage increase in system back pressure based on a comparison of system back pressure associated with a filter not loaded with catalyst to a system with a filter loaded with catalyst as measured by an average of cold flow values at a space velocity in the range of about 20,000 hr"1 and 120,000 hr"1; and passing the gas stream through a particulate filter having a particulate filtration efficiency in the range of about 30% and 60% by mass disposed downstream of the engine, the particulate filter loaded with a SCR catalyst having a loading in the range of about 0.1 g/in3 and 3.5 g/in3 effective for NOx conversion the catalyst disposed on the filter substrate from 10 to 100% of its length.

12. A method of treating an engine exhaust gas stream containing an initial NOx concentration and effective for conversion of NOx, the gas stream having a system back pressure and a system NOx conversion, the method comprising: defining an exhaust gas system operational window based on a minimum targeted system NOx conversion and a maximum targeted percentage increase in system back pressure, the percentage increase in system back pressure based on a comparison of system back pressure associated with a filter not loaded with catalyst to a system with a filter loaded with catalyst as measured by an average of cold flow values at a space velocity in the range of about 20,000 hr"1 and 120,000 hr"1; passing the gas stream through a particulate filter having a particulate filtration efficiency in the range of about 30% and 60% disposed downstream of the engine, the particulate filter loaded with a first SCR catalyst having a loading in the range of about 0.1 g/in3 and 3.5 g/in3 effective for NOx conversion, the catalyst disposed on the partial filter substrate from 10 to 100% of its length, the gas stream having an intermediate NOx concentration after passing through the particulate filter; injecting ammonia or an ammonia precursor into the exhaust gas system upstream of the particulate filter; and passing the gas stream having the intermediate NOx concentration through a second substrate loaded with a second SCR catalyst disposed downstream of the particulate filter effective for NOx conversion, wherein the gas stream exiting the emissions treatment system has a final NOx concentration, and wherein the system NOx conversion and the system back pressure are within the operational window.

13. The method of treating an engine exhaust gas stream according to claim 11 or 12, wherein the system N0χ conversion is in the range of about 50% and 100%.

14. The method of treating an engine exhaust gas stream according to claim 11 or 12, wherein there is no intervening SCR catalyst disposed between the engine and the particulate filter.

15. The method of treating an engine exhaust gas stream according to claim 11 or 12, wherein the minimum targeted system NOx conversion is about 50% and the maximum targeted percentage increase in system back pressure is about 25%.