| abstract |
Provided are catalysts and methods thereof for selectively reducing nitrogen oxides ("NO x ") using ammonia. The catalyst is a zeolite selected from the group consisting of ZSM-5, ZSM-11, ZSM-12, ZSM-18, ZSM-23, MCM-zeolite, mordenite, possite, ferrierite, zeolite beta and mixtures thereof Or a first component comprising a mixture of zeolites; Cerium, iron, copper, gallium, manganese, chromium, cobalt, molybdenum, tin, rhenium, tantalum, osmium, barium, boron, calcium, strontium, potassium, vanadium, nickel, tungsten, actinides, mixtures of actinides, lanthanides A second component comprising at least one member selected from the group consisting of a mixture of lanthanides, and mixtures thereof; Optionally oxygen storage material and optionally inorganic oxides. The catalyst selectively reduces nitrogen oxides using ammonia to nitrogen at high temperatures. The catalyst has high hydrothermal stability. The catalyst has a high activity in the conversion of low levels of nitrogen oxides in the exhaust stream. The catalyst and method are particularly applicable to the selective reduction of nitrogen oxides in exhaust gases from gas turbines and gas engines, but the catalyst and method are widely applied to a wide range of gas streams with excess oxygen and high temperatures. The temperature of the exhaust gas from the gas turbine and the gas engine is high. Both high and low levels of inlet NO x are challenging in the case of selective catalytic reduction (SCR) catalysts. |