Patent ID: 8178064

Claim:
A method for treating a gas stream generated by a stationary combustion source, said method comprising: contacting a first exhaust stream from a stationary combustion source with a selective reduction catalyst, wherein said first exhaust stream comprises nitrogen oxide and a reductant comprising a hydrogen-containing compound, and wherein the selective reduction catalyst is effective to reduce nitrogen oxide to ammonia under the steady state conditions of the gas stream generated by the stationary combustion source, thereby reducing a portion of said nitrogen oxide to ammonia to produce a second exhaust stream comprising nitrogen oxide and ammonia, and contacting said second exhaust stream with an ammonia selective catalyst, wherein the ammonia selective catalyst is effective to reduce nitrogen oxide to nitrogen gas and water under the steady state conditions of the gas stream generated by the stationary combustion source, thereby reducing at least some of said nitrogen oxide in said second exhaust stream to nitrogen gas and water to produce a third exhaust stream, thereby treating said gas stream.