Effect of Sodium in Ferrierite on Selective Catalytic Reduction of NO by Acetylene

Abstract

Influence of sodium in ferrierite (HFER) zeolite on selective catalytic reduction of NO by acetylene (C 2 H 2 -SCR) was investigated. NO x -TPD and FT-IR indicated that small amount of sodium exchanged into the proton-form zeolite with an exchange level of about 11.8% is beneficial for the title reaction by accelerating active nitrate species formation on catalyst surface from NO 2 and by suppressing the reductant combustion. Nevertheless, no further improved catalytic performance in C 2 H 2 -SCR could be observed by a larger amount of sodium exchanged into HFER due to some inactive nitrate species formed on the zeolite. Instead, activity of the zeolite for C 2 H 2 -SCR was drastically reduced, since the capacity of the zeolite for catalyzing NO oxidation and accelerating active NO + species formation was remarkably depressed.