Exhaust After Treatment System

An exhaust gas treatment system for reducing constituents in the exhaust gas of an internal combustion engine comprising:

• a ceramic wall flow monolith filter disposed within the exhaust gas treatment system;
• exhaust flow passages extending through the ceramic wall flow monolith filter defined by longitudinally extending walls therebetween;
• a first subset of exhaust flow passages having an open inlet end and a closed outlet end defining inlet passages;
• a second subset of exhaust flow passages having a closed inlet end and an open outlet end defining outlet passages, wherein exhaust gas enters the ceramic wall flow monolith filter through the inlet passages and migrates through, and is filtered by, the longitudinally extending walls to exit the ceramic wall flow monolith filter through the outlet passages;
• a first catalyst composition, operable with an ammonia reductant to catalytically reduce oxides of nitrogen in the exhaust gas, applied to a first portion of the ceramic wall flow monolith filter;
• and
• a second catalyst composition, for catalytic oxidation of hydrocarbon, carbon monoxide and ammonia in the exhaust gas, separately applied, serially downstream to a second portion of the ceramic wall flow monolith filter.

An exhaust gas treatment system for reducing constituents in the exhaust gas of an internal combustion engine comprising:

• an oxidation catalyst disposed within the exhaust gas treatment system;
• a particulate filter downstream of the oxidation catalyst to remove particulates from the exhaust gas;
• a first catalyst composition, operable to catalytically reduce oxides of nitrogen in the exhaust gas, applied to a first portion of the particulate filter;
• and
• a second catalyst composition, for catalytic oxidation hydrocarbon, carbon monoxide and ammonia in the exhaust gas, applied serially downstream to a second portion of the particulate filter.