Poisoning effect of CaO on Cu/ZSM-5 for the selective catalytic reduction of NO with NH3

The influence of the presence of CaO in the Cu/ZSM-5 catalyst on the selective catalytic reduction of NO by NH3 was investigated. A series of samples containing different amounts of Ca loading have been prepared by the incipient wetness impregnation method. The catalysts were characterized using N-2 adsorption/desorption, powder XRD, H-2-TPR, NH3-TPD and XPS techniques. The Ca loading led to a decrease in the ability for reduction of CuO, a loss of the surface acid sites and a decrease in the surface concentration of Cu, which all appear responsible for the deactivation of Ca-impregnated Cu/ZSM-5 catalysts.