SELECTIVE REDUCTION TYPE NOX CATALYST AND METHOD FOR PRODUCTION THEREOF

摘要

PROBLEM TO BE SOLVED: To provide a method for production of an NOx catalyst expressing suitable NOx reduction property due to an Fe element, and to the NOx catalyst.SOLUTION: There is provided the method for production of a selective reduction type NOx catalyst formed through the ion exchange of a zeolite crystal with an Fe element expressing selective reduction with respect to NOx. The method comprises: an ion exchange step of immersing the zeolite crystal having a pore size larger than the diameter of a hexa-aqua iron (III) complex into a prescribed aqueous solution in which the Fe element exists in the shape of the hexa-aqua iron (III) complex to perform the ion exchange of the Fe element in the pore of the zeolite crystal; and a diameter reduction step of reducing the opening diameter of an opening portion in the pore of the zeolite crystal to a prescribed diameter through which the prescribed HC (hydrocarbon) components cannot pass, but NOx is passable by precipitating at least silane oxide on the external surface of the zeolite crystal in which the ion exchange of the Fe element is carried out to cover a part of the opening portion of the pore.SELECTED DRAWING: Figure 3B