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

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, N-2 sorption, ICP,(27)AlMAS NMR, H-2-TPR, XPS, and UV-vis DRS. It was concluded that isolated Co2+ cations, in particular alpha-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. (C) 2015 Elsevier B.V. All rights reserved.