Outstanding Stability and Enhanced Catalytic Activity for Toluene Oxidation by Si–O–Mn Interaction over MnO_<i>x</i>/SiO₂

Abstract

Emissions of volatile organic compounds (VOCs) have caused serious damage to the environment and public health. Catalytic combustion is an efficient technology for VOC elimination. In this study, porous silica supported amorphous MnOx was constructed. It presented excellent stability and high activity for toluene combustion, even under the high humidity (T90 = 218 °C). Compared with bulk amorphous MnOx, the catalytic activity has been improved by more than 11 times. The various characterizations and quantum chemical calculation results suggested that the Si–O–Mn hybridization induced weakening of the Mn–O bond strength and electron transfer from the catalyst to surface oxygen species. A promoting effect of the Si–O–Mn interaction on the spillover of active O species was proposed which enhanced the catalytic activity. In-situ DRIFTS and XPS analytical results determined the reaction mechanism and revealed that both Olatt and Osurf participate in the catalytic oxidation of toluene. The problem of the poor thermal stability of amorphous MnOx has been solved in this work. This work provides a convenient and effective method to prepare efficient catalysts with high activity and good thermal stability for VOC catalytic combustion.