Catalyzed filter for treating exhaust gas

A system for treating an exhaust gas comprising:

• a. a catalytic wall-flow filter comprising
• i. a porous substrate having inlet and outlet faces;
• and
• ii. an SCR catalyst composition coated on at least one of the porous substrate inlet face, outlet face, and between said inlet and outlet faces, wherein the catalyst composition comprises transition metal promoted molecular sieve crystals, wherein:
• said crystals have a mean crystalline size of about 0.5 μm to about 15 μm, said crystals are present in said composition as individual crystals, agglomerations having a mean particle size of less than about 15 μm, or a combination of said individual crystals and said agglomerations, and
• said molecular sieve is an aluminosilicate or a silico-aluminophosphate of a Framework Type having a maximum ring size of eight tetrahedral atoms,
• b. a conduit connecting the wall-flow filter with a source of lean burn exhaust gas containing particulate matter and NOx, and
• c. a reductant supply system for introducing a reductant into a lean combustion exhaust gas, wherein the reductant supply system is in fluid communication with the catalytic wall-flow filter and is disposed upstream of the catalytic wall-flow filter relative to gas flow through the filter.

A method for treating an exhaust gas comprising:

• a. passing a lean combustion exhaust gas comprising particulate matter and NOx through a catalytic wall-flow filter comprising:
• i. a porous substrate having inlet and outlet faces;
• and
• ii. an SCR catalyst composition coated on at least one of the porous substrate inlet face, outlet face, and between said inlet and outlet faces, wherein the catalyst composition comprises transition metal promoted molecular sieve crystals, wherein:
• said crystals have a mean crystalline size of about 0.5 μm to about 15 μm, said crystals are present in said composition as individual crystals, agglomerations having a mean particle size of less than about 15 μm, or a combination of said individual crystals and said agglomerations, and
• said molecular sieve is an aluminosilicate or a silico-aluminophosphate of a Framework Type having a maximum ring size of eight tetrahedral atoms,
• wherein said passing separates at least a portion of said particulate matter from said exhaust gas to form a partially purified exhaust gas;
• b. contacting, in the presence of a reducing agent, at least one of the lean combustion exhaust gas and the partially purified exhaust gas with the SCR catalyst composition to selectively reduce at least a portion of the NOx to N2 and other components.