Patent ID: 7811527

Claim:
A method of ammonia production for a selective catalytic reduction system, comprising: producing an exhaust gas stream within a cylinder group, wherein the exhaust gas stream includes NOx; supplying the exhaust gas stream to an exhaust passage upstream of a catalyst configured to convert at least a portion of the NOx in the exhaust gas stream into ammonia, the catalyst having a NOx-to-ammonia conversion efficiency that varies with temperature; cooling the exhaust gas stream to a predetermined temperature range based on the NOx-to-ammonia conversion efficiency of the catalyst; and exposing the exhaust gas stream to the catalyst to convert at least a portion of the NOx within the exhaust gas stream into ammonia to produce an exhaust gas stream containing ammonia; producing a second exhaust gas stream containing NOx with a second cylinder group; supplying the second exhaust gas stream to a second exhaust passage; combining the exhaust gas stream containing ammonia with the second exhaust gas stream containing NOx to produce a merged exhaust gas stream; and passing the merged exhaust gas stream through a second catalyst to cause a reaction between ammonia and NOx, thereby reducing the amount of NOx in the merged exhaust gas stream.