| abstract |
Provided is an emissions treatment system and method for reducing NO x emissions in the exhaust stream produced from an internal combustion engine. The system has an injector for periodically metering ammonia or an ammonia precursor into an exhaust stream; and a first substrate with a first SCR catalyst composition, downstream of the injector. The first substrate has an inlet end, an outlet end, a length extending between the inlet end to the outlet end, and wall elements. The first SCR catalyst composition is disposed on the wall elements from the inlet end toward the outlet end to form an inlet zone. The first substrate also has an NH 3 destruction catalyst composition with a platinum group metal component dispersed on a refractory metal oxide. The NH 3 destruction catalyst is disposed on the wall elements from the outlet end to form an outlet zone. |