Boosting diethylamine selective oxidation over CuO/ZSM-5 catalyst by CeO2 modification

Abstract

Selective catalytic oxidation of nitrogen containing volatile organic compounds (NVOCs) is very meaningful but still remains big challenge because it is very difficult to balance the oxidation activity and N2 selectivity of available catalysts. In order to develop excellent catalysts with high N2 selectivity in wide temperature window (△T) during NVOCs oxidation, CeO2 modified CuO/ZSM-5 catalysts with different CeO2 addition order were prepared for diethylamine (DEA) oxidation. Detailed characterizations of catalysts such as XRD, XPS, H2-TPR and NH3-TPD were conducted, it is found that addition of CeO2 obviously changes the geometrical and electronic states of CuO active sites in the catalyst, and CeO2 addition order affects the Ce3+ ratio on the catalyst surface. Promotion of CeO2 species enables the generation of more highly active Cu species (Cu+ species and finely dispersed CuO clusters) for DEA oxidation; and synergistic catalysis of the Ce3+ species, active Cu species and acid sites in ZSM-5 leads to the high N2 selectivity in wide temperature window (△T). Compared to the CeO2/CuO/ZSM-5 and CuO-CeO2/ZSM-5 catalysts, the CuO/CeO2/ZSM-5 catalyst exhibits moderate high oxidation activity with T99 of 230 °C and the widest △T of 150 °C for high N2 selectivity. Our primary results in this work provide the efficient strategy for improving catalyst employed for NVOCs selective oxidation.