Patent ID: 7533521

Claim:
A method of generating reductant in at least a portion of an exhaust stream comprising: injecting fuel into the exhaust stream upstream of a fuel processor, wherein the fuel processor comprises an inlet, an outlet, and at least one steam reforming catalyst, and the exhaust stream comprises oxygen, whereby the injection of fuel leaves the exhaust stream overall lean and rapidly increases the temperature of at least a portion of the fuel processor to within the range from about 500° C. to about 750° C.; implementing one or a combination of strategies selected from the group consisting of increasing the fuel injection rate, decreasing the oxygen concentration in the exhaust stream, and decreasing the exhaust flow, to obtain rich conditions on at least a portion of the fuel processor catalyst; and allowing the fuel and exhaust stream mixture to react within the at least one fuel processor catalyst to generate a reducing gas mixture comprising CO and H 2 ; wherein the exhaust upstream from the fuel processor is at a temperature of 300° C. or less and the fuel processor has a thermal mass sufficiently low that at least a portion of the fuel processor heats to within the range from about 500° C. to about 750° C. in 12 seconds or less.