Roles of ZnO in Cu/Core-Shell Al-MCM-41 for NO Reduction by Selective Catalytic Reduction with NH: The Effects of Metal Loading and Cu/ZnO Ratio.

Cu-ZnO/Al-MCM-41 catalysts were studied for NO reduction. The total metal loading was varied as 3, 5, and 7 wt %, whereas the Cu-to-ZnO ratio was fixed at 1:1. Too high metal loading led to lower reducibility of Cu, as CuO and ZnO covers on the catalyst surface could partially block pores and hinder gas molecules to access the Cu ions. Subsequently, Cu loading was fixed at 2.5 wt %, whereas ZnO content was varied as 0, 2.5, and 3.5 wt %. The results demonstrated that 2.5Cu-2.5ZnO catalyst exhibits the best catalytic activity, as it gave the average NO conversion of 87%.