Plasma-catalytic removal of toluene over the supported manganese oxides in DBD reactor: Effect of the structure of zeolites support.

The degradation of toluene in dielectric barrier discharge (DBD) reactor packed with zeolites or MnOx/zeolites was investigated. The supported catalysts were prepared by loading 3 wt% of manganese on different zeolites (MCM-41, ZSM-5 and 13X) and were characterized in detail using N2 adsorption, XRD, TEM, H2-TPR and XPS analysis technology. Compared to the non-thermal plasma (NTP) alone system, the toluene degradation was improved significantly in NTP-MnOx/zeolites system. The highest toluene conversion of 99.4%, the CO2 selectivity of 73%, the carbon balance of 99.5% can be achieved in DBD reactor packed with MnOx/MCM-41. Both XRD and TEM results confirm that the manganese oxides were dispersed more uniformly on MnOx/MCM-41 than on MnOx/ZSM-5 or MnOx/13X. H2-TPR and XPS results suggest that manganese oxides on MnOx/MCM-41 are MnO2 and Mn2O3, while those on MnOx/ZSM-5 or MnOx/13X are MnO2 and MnO. These results indicate that the structures of zeolites play a significant role in the dispersion and oxidation state of manganese oxides, then affecting the activity of catalyst for toluene removal in plasma-catalysis system.