ZONE COATED CATALYST, CATALYST SYSTEM AND METHOD TO SIMULTANEOUSLY REDUCE NOx AND UNREACTED AMMONIA

Provided is a catalyst article and an emissions treatment system and method for reducing NOx 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 and a first substrate with a first SCR catalyst composition, downstream of the injector. The catalyst article comprises a substrate. The substrate of the and the first substrate of the system has an inlet end, an outlet end, a length extending between the inlet end to the outlet end, wall elements and a plurality of passages defined by the wall elements. An SCR composition is dispose on the wall elements from the inlet end towards the outlet end to a length that is less than the substrate's axial length to form an inlet zone. The substrate also as 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 toward the inlet end to a length that is less the substrate's axial length to form an outlet zone. Generally, there is from 0.1 to 10 g/ft 3 of platinum group metal component in the outlet zone.