CoZSM-11 catalysts for N2O decomposition: Effect of preparation methods and nature of active sites

Abstract

CoZSM-11 catalysts prepared using different methods (i.e., wet ion exchange, buffered ion exchange, semi-continuous ion exchange, and impregnation) were tested in N2O decomposition. For CoZSM-11 catalysts prepared by wet ion exchange, the activity increased with the decrease of the Si/Al ratio. Even higher activities can be achieved using catalysts prepared by buffered ion exchange or semi-continuous ion exchange. In contrast, CoZSM-11 prepared by impregnation was the least active. The catalysts were characterized by XRD, N2 sorption, ICP, 27Al MAS NMR, H2-TPR, XPS, and UV–vis DRS. It was concluded that isolated Co2+ cations, in particular α-type Co2+, were active sites, whereas the CoOx species obtained by impregnation was much less active. The catalytic performance of CoZSM-11 and CoZSM-5 was compared as well.