HIGHLY HYDROTHERMAL-RESISTANT SCR CATALYST AND MANUFACTURING METHOD THEREFOR

摘要

An SCR catalyst including iron-containing &bgr;-type zeolite has high NOx reducing performance at a high temperature in the presence of a reducing agent, but does not have the sufficient reducing performance at a low temperature (not higher than 200° C.). A high NOx reduction rate of at least 45% at a temperature not higher than 200° C. is achieved by an SCR catalyst containing iron-containing &bgr;-type zeolite having a full width at half maximum (FWHM) on the X-ray crystal diffraction (302) plane of from 0.28 to 0.34° and a weight loss on heating to 900° C. after hydration treatment of from 15.0 to 18.0% by weight. The SCR catalyst can be manufactured by calcining iron-containing &bgr;-type zeolite at 700 to 850° C. under an atmosphere of a water vapor concentration of not more than 5% by volume.