Characterization of Fe-silicates and their catalytic properties for the selective reduction of nitric oxide by hydrocarbons

Abstract

H-form Fe-silicate (H-Fe-silicate) catalysts having various Si/Fe molar ratios were synthesized and used for the reduction of NO by hydrocarbons. The results of the chemical analyses, NH 3-TPD, X-ray photoelectron spectroscopy (XPS) and TPR, showed that the non-framework iron content increased with increasing content of iron. Olefins (C 3H 6 and C 2H 4) were more effective reducing agents than parafins (C 3H 8, C 2H 6). The active temperature region for NO reduction by C 3H 6, became lower with increasing iron content in the Fe-silicates, while both the number of acid sites and the NO conversion to N 2 was approximately constant independent of the iron content. Therefore, the iron incorporated in zeolite framework provided acid sites that controlled the catalytic activity for selective reduction.