| 摘要 |
<p>An exhaust gas purification method for reducing selectively NOx in exhaust gas, which is exhausted from a lean burn engine, such as a boiler, a gas turbine or a lean-burn-type gasoline engine, a diesel engine, with a selective reduction catalyst and ammonia, characterized in that
an aqueous solution of urea is spray-supplied to the selective reduction catalyst, comprising at least the following zeolite (A) and the hydrolysis promotion component of urea (B), and it is contacted at 150 to 600ºC, and ammonia is generated in a ratio of [NH3/NOx=0.5 to 1.5] to NOx in exhaust gas, as converted to ammonia, and a nitrogen oxide is decomposed into nitrogen and water;
·zeolite (A): zeolite comprising an iron element
·hydrolysis promotion component (B) : a complex oxide comprising at least one kind selected from titania or titanium, zirconium, tungsten, silicon or alumina.
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