NOX SELECTIVE REDUCTION CATALYST

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PROBLEM TO BE SOLVED : To suppress deterioration of NOx selective reduction activity in the case of exposure to high temperature environments containing steam. SOLUTION : The NOx selective reduction catalyst is a catalyst for selectively reducing NOx by NH3 and contains Fe and a rare earth metal (M)-ion exchanged zeolite. Dealuminization is suppressed in the case of exposure to high temperature environments containing steam and high NOx selective reduction activity can be maintained for a long duration by ion exchange with rare earth metal (M). Further, since the rare earth metal (M) is weak in the basicity, the acidic property of the zeolite is not deteriorated and both of dealuminization and decrease of the NOx selective reduction activity can be suppressed. The catalytic function of Fe by the rare earth metal (M) is hardly inhibited by the rare earth metal (M). COPYRIGHT : (C)2007, JPO&INPIT