Catalytic process for NOX reduction under lean conditions

Claim 1

A process for effecting the selective reduction of NO x in lean effluent waste streams containing NO x , CO, O 2 , H 2 , CO 2 and water, wherein the concentration of CO is at least equivalent to the concentration of NO x present in the waste stream, a lean effluent waste stream being defined as one in which the concentration of oxygen is in excess over the concentration of reductants to a level as high as 8%, i.e., about 800% excess oxygen, over the total of reductants present, said reductants being selected from the group comprising CO and H 2 so that when such a waste stream is reacted to completion, the residuum is oxidizing in character, said process comprising the steps of contacting said lean exhaust stream in a reaction zone with an iridium catalyst, said contacting occurring at a temperature between 300° to 750° C. thereby effecting the selective reduction by CO of the oxides of nitrogen to molecular nitrogen.