Exhaust treatment system for an internal combustion engine

An exhaust gas treatment system for an internal combustion engine comprising:

• an exhaust gas conduit in fluid communication with, and configured to receive an exhaust gas from the internal combustion engine;
• a selective catalytic reduction device comprising a flow-through substrate packaged in a rigid canister having an inlet and an outlet in fluid communication with the exhaust gas in the exhaust gas conduit;
• a selective catalytic reduction composition disposed on the flow-through substrate for reduction of oxides of nitrogen (“NOx”) in the exhaust gas in the presence of an ammonia reductant;
• a particulate filter device having a wall-flow substrate configured to filter the exhaust gas of carbon and other particulates disposed in the rigid canister downstream of the selective catalytic reduction device;
• a dosing system comprising a controller in signal communication with a NOx sensor located upstream of the selective catalytic reduction device and a NOx sensor located downstream of the particulate filter device and configured to inject ammonia into the exhaust gas upstream of the selective catalytic reduction device based on information collected by the controller from the upstream and the downstream NOx sensors to thereby optimize the reduction of NOx therein;
• and
• an ammonia-neutral oxidation catalyst compound, that is substantially un-reactive with respect to ammonia in the exhaust gas, is dispersed into the wall-flow substrate of the particulate filter device and configured to pass-through ammonia constituents of the exhaust gas exiting the selective catalytic reduction device such that little or none of the ammonia is converted to NOx.