Abstract

The selective catalytic reduction of NO by ammonia in the presence of excess oxygen has been studied over mono-metallic Ag/ZSM-5 and bimetallic M-Ag/ZSM-5 (M: Mn, Fe and Ni) nanocatalysts. Ag/ZSM-5 showed a good activity, but produced amount of N2O and selectivity to N2 was low. The modification of Ag/ZSM-5 catalyst was carried out through the addition of different transition metals (Mn, Fe and Ni) for improvement of N2 selectivity. Fe-Ag/ZSM-5 bimetallic nanocatalyst showed the highest activity of 95% NO conversion and 73% selectivity to N2 at 300°C. Several techniques, X-ray diffractometry (XRD), Transmission electron microscopy (TEM), Nitrogen adsorption-desorption (BET), Ammonia temperature-programmed desorption (NH3-TPD), and X-ray photoelectron spectroscopy (XPS), were employed to characterize of Ag/ZSM5 and M-Ag/ZSM-5 nanocatalysts. TEM results revealed nano-size of metal species particles on H-ZSM-5 support in M-Ag/ZSM-5 catalysts and high dispersion of metal species in Fe-Ag/ZSM-5 catalyst. The NH3-TPD studies also confirmed that Fe-Ag/ZSM-5 catalyst had more acidic strength and NH3 storage capacity in comparison to other catalysts.