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Emissions treatment systems and methods for treating an engine exhaust gas stream containing NOx and particulate matter are disclosed including a particulate filter comprising a first SCR catalyst for NOx conversion a second SCR catalyst for NOx conversion on a substrate disposed downstream of the p

Emissions treatment systems and methods for treating an engine exhaust gas stream containing NOx and particulate matter are disclosed including a particulate filter comprising a first SCR catalyst for NOx conversion a second SCR catalyst for NOx conversion on a substrate disposed downstream of the particulate filter. The system NOx conversion and the system back pressure increase lie within a targeted operational window.

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1. An emissions treatment system for treating an engine exhaust gas stream containing an initial NOx concentration and particulate matter, the system providing a system back pressure and a system NOx conversion, the system comprising: a reductant injector;a honeycomb wall flow filter comprising a fi

1. An emissions treatment system for treating an engine exhaust gas stream containing an initial NOx concentration and particulate matter, the system providing a system back pressure and a system NOx conversion, the system comprising: a reductant injector;a honeycomb wall flow filter comprising a first SCR catalyst effective for NOx conversion disposed downstream of the reductant injector and having a loading in the range of about 0.1 g/in3 and 2.5 g/in3 with no intervening SCR catalysts disposed between the engine and the honeycomb wall flow filter; anda flow through substrate loaded with a second SCR catalyst effective for NOx conversion disposed downstream of the honeycomb wall flow filter, the honeycomb wall flow filter catalyst loading effective to provide a system back pressure that is less than about 25% greater than system back pressure associated with a similar system including a filter not loaded with catalyst and the system NOx conversion is in the range of about 50% and 100%. 2. The emissions treatment system of claim 1, further comprising an oxidation catalyst disposed downstream of the honeycomb wall flow filter. 3. The emissions treatment system of claim 1, wherein the first SCR catalyst comprises a material that provides a NOx conversion at the first SCR catalyst of at least about 25% at 250° C. for an exhaust gas stream at a space velocity of about 80,000 h−1 when the gas stream comprises about 500 ppm NO, about 500 ppm NH3 and about 5% water in air. 4. The emissions treatment system of claim 1, further comprising an oxidation catalyst disposed upstream of the honeycomb wall flow filter. 5. The emissions treatment system of claim 4, wherein the treatment system is operative to provide an intermediate NOx concentration after the gas stream passes through the honeycomb wall flow filter and a final NOx concentration after the gas stream passes through the 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. 6. The emissions treatment system of claim 5, wherein the first SCR catalyst is coated on an axial length of the honeycomb wall flow filter that is less than the total axial length of the filter. 7. The emissions treatment system of claim 5, wherein conversion of NOx passing through the honeycomb wall flow filter is in the range of about 10% and 90% of the system NOx conversion. 8. The emissions treatment system of claim 7, wherein the first SCR catalyst comprises a material that provides a NOx conversion at the first SCR catalyst of at least about 30% at 250° C. as measured at steady state at a space velocity of about 80,000 h−1. 9. The emissions treatment system of claim 5, wherein the second SCR catalyst comprises a mixed oxide of V2O5, WO3 and TiO2. 10. The emissions treatment system of claim 5, wherein the first SCR catalyst and the second SCR catalyst are the same. 11. The emissions treatment system of claim 5, wherein the first SCR catalyst and the second SCR catalyst are different, the first SCR catalyst being operable for NOx conversion at higher gas stream temperatures and the second SCR catalyst being operable for NOx conversion at lower gas stream temperatures. 12. The emissions treatment system of claim 11, wherein the second SCR catalyst comprises a zeolite containing Cu and having a CHA structure. 13. The emissions treatment system of claim 5, wherein the minimum targeted system NOx conversion is about 60% and the maximum targeted percentage increase in system back pressure is about 25%. 14. The emissions treatment system of claim 13, wherein the honeycomb wall flow filter comprises a plurality of longitudinally extending walls and at least about 70% by volume of the first SCR catalyst is located within the walls of the honeycomb wall flow filter. 15. The emissions treatment system of claim 14, wherein at least about 80% by volume of the first SCR catalyst is located within the walls of the honeycomb wall flow filter. 16. The emissions treatment system of claim 15, wherein at least about 90% by volume of the first SCR catalyst is located within the walls of the honeycomb wall flow filter. 17. The emissions treatment system of claim 13, wherein the honeycomb wall flow filter is a high efficiency filter which removes at least about 70% of the particulate matter in the gas stream. 18. The emissions treatment system of claim 17, wherein the honeycomb wall flow filter is a high efficiency filter which removes at least about 80% of the particulate matter in the gas stream. 19. The emissions treatment system of claim 13, wherein the honeycomb wall flow filter has a porosity in the range of about 40% and 90%. 20. The emissions treatment system of claim 19, wherein the honeycomb wall flow filter has a porosity in the range of about 40% and 80%. 21. The emissions treatment system of claim 20, wherein the honeycomb wall flow filter has a porosity in the range of about 40% and 70%. 22. The emissions treatment system of claim 13, wherein the first SCR catalyst comprises a zeolite containing Cu and having a CHA structure. 23. The emissions treatment system of claim 13, wherein the second SCR catalyst comprises a zeolite containing Cu having a CHA structure. 24. The emissions treatment system of claim 13, wherein the first SCR catalyst comprises a mixed oxide of V2O5, WO3 and TiO2. 25. The emissions treatment system of claim 13, wherein the first SCR catalyst comprises a Fe containing zeolite. 26. The emissions treatment system of claim 13, wherein the second SCR catalyst comprises a Fe containing zeolite. 27. A method of treating an engine exhaust gas stream having an initial NOx concentration and effective for conversion of NOx, 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;passing the gas stream through a honeycomb wall flow filter disposed downstream of the engine, the honeycomb wall flow filter loaded with a first SCR catalyst effective for NOx conversion, the gas stream having an intermediate NOx concentration after passing through the honeycomb wall flow filter, wherein there is no intervening SCR catalyst between the honeycomb wall flow filter and the engine, the exhaust gas stream containing a reductant comprising one or more of hydrocarbons, ammonia, urea and ammonia precursors; andpassing the gas stream having the intermediate NOx concentration through a second substrate loaded with a second SCR catalyst disposed downstream of the honeycomb wall flow 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. 28. The method of treating an engine exhaust gas stream of claim 27, wherein the honey comb wall flow filter has a porosity in the range of about 50% and 80% and has a loading of SCR catalyst in the range of about 0.1 g/in3 and 1.8 g/in3. 29. The method of claim 28, wherein the first SCR catalyst is coated on an axial length of the honeycomb wall flow filter that is less than the total axial length of the filter. 30. The method of treating an engine exhaust gas stream of claim 27, wherein the system NOx conversion is in the range of about 50% and 100% of the initial NOx concentration. 31. The method of treating an engine exhaust gas stream of claim 27, wherein conversion of NOx by the honeycomb wall flow filter is in the range of about 10% to about 90% of the system NOx conversion. 32. The method of treating an engine exhaust gas stream of claim 31, wherein the minimum targeted system NOx conversion is about 60% and the maximum targeted percentage increase in system back pressure is about 25%.