Modulating multi-active sites in CeO2-modified MnOx/ZSM-5 catalyst for selective catalytic oxidation of diethylamine

Abstract

An efficient MnOx/CeO2/ZSM-5 catalyst was developed for selective oxidation of diethylamine (DEA) with high N2 selectivity in a wide temperature window (ΔT = 140 °C), owing to the existence of oxidation and selective catalytic reduction (SCR) active sites. MnOx species prefer to locate on the surface of CeO2 compared to ZSM-5, and the presence of CeO2 is beneficial to form more Mn4+ species, the active sites for oxidation reaction. The mechanistic investigation suggests that internal SCR of NOx generated from the over-oxidized DEA is the crucial pathway for N2 generation. The high SCR activity of the MnOx/CeO2/ZSM-5 catalyst in oxidation conditions is mainly attributed to the synergistic catalysis of Mn4+ species and acid sites of ZSM-5, the active sites for SCR reaction. Thus, it has been clearly clarified that addition of CeO2 and its addition sequence could modulate the surface active sites of MnOx/ZSM-5 catalyst for the selective catalytic oxidation of DEA.