Patent ID: 8609047

Claim:
A filter comprising a catalyst for converting oxides of nitrogen in the presence of a reducing agent, the filter comprising: 10-95% by weight of at least one binder/matrix component; 5-90% by weight of a zeolitic molecular sieve, a non-zeolitic molecular sieve or a mixture of any two or more thereof; and 0-80% by weight optionally stabilised ceria, wherein the filter is a wall-flow filter having an extruded solid body, and the catalyst comprising at least one metal, wherein: (i) the at least one metal is present throughout the extruded solid body and is also present in a higher concentration at a surface of the extruded solid body; (ii) the at least one metal is present throughout the extruded solid body and is also carried in one or more coating layer(s) on a surface of the extruded solid body; or (iii) the at least one metal is present throughout the extruded solid body, is present in a higher concentration at a surface of the extruded solid body and is also carried in one or more coating layer(s) on the surface of the extruded solid body.