Patent ID: 7772151

Claim:
A catalyzed soot filter comprising a porous monolithic ceramic honeycomb body having an inlet end and outlet end connected by adjacent inlet and outlet channels that extend from the inlet end to the outlet end of the ceramic body, the inlet and outlet channels being defined by a plurality of interlaced thin gas filtering porous partition walls between the inlet and outlet channels and by ceramic plugs, such that the inlet channel has an inlet ceramic plug at the outlet end of the ceramic body and the outlet channel has an outlet ceramic plug at the inlet end of the ceramic body such that a fluid when entering the inlet end must pass through partition walls to exit the outlet end, wherein the ceramic honeycomb body has an inlet catalyzed zone comprising at least one filtering porous partition wall having a catalyst consisting within the pores of the wall from the inlet end to at most about 45% of the length of the ceramic honeycomb wall-flow filter said inlet catalyzed zone having a porosity no less than about ⅓ and no more than 31/32 of the porosity of said filtering partition wall without catalyst and wherein the catalyzed soot filter has an outlet zone extending from the outlet end to the inlet catalyzed zone, said outlet zone having a pressure drop across the partition wall of the outlet zone that is lower than the pressure drop across the partition wall of the inlet catalyzed zone.