Study of M-ZSM-5 nanocatalysts (M: Cu, Mn, Fe, Co …) for selective catalytic reduction of NO with NH3: Process optimization by Taguchi method

Abstract

A series of different transition metals (V, Co, Cr, Mn, Fe, Ni, Cu and Zn) promoted H-ZSM-5 catalysts were prepared by impregnation method and characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The catalytic activity of these catalysts was evaluated for the selective catalytic reduction (SCR) of NO with NH3 as reductant in the presence of oxygen. The results revealed that the catalytic activity of Cu-ZSM-5 nanocatalyst for NO conversion to N2 was 80% at 300°C, which was the best among various promoted metals. Design of experiments (DOEs) with Taguchi method was employed to optimize NH3-SCR process parameters such as NH3/NO ratio, O2 concentration, and gas hourly space velocity (GHSV) over Cu-ZSM-5 nanocatalyst at 250 and 300°C. Results showed that the most important parameter in NH3-SCR of NO is O2 concentration; followed by NH3/NO ratio and GHSV has little importance. The NO conversion to N2 of 63.1% and 94.86% was observed at 250°C and 300°C, respectively under the obtained optimum conditions.