Removal of chlorobenzene over LaMnO3 and OMS-2 catalysts in a dielectric barrier discharge reactor

Abstract

Plasma-catalytic removal of chlorobenzene (CB) was conducted in a dielectric barrier discharge (DBD) reactor over two manganese-based catalysts, LaMnO3 and cryptomelane-type octahedral molecular sieve (OMS-2). The physicochemical properties of two catalysts were characterized by XRD, SEM, TEM, BET, XPS and H2-TPR. It was shown that OMS-2 catalyst had larger surface area, smaller particle size, better redox properties, higher ratio of Mn4+/Mn3+ and higher content of surface-adsorbed oxygen (Oads). The introduction of manganese-based catalysts enhanced CB removal, increased the CO2 selectivity, and inhibited ozone (O3) and NOx formation. OMS-2 exhibited a better degradation, mineralization and energy yield, with 89.5% of CB degradation, 57.6% of CO2 selectivity and 0.54 g kWh−1 at discharge voltage of 6 kV, than LaMnO3 in the NTP-catalytic reactor and this was ascribed to more active sites, more Oads, higher redox property and better O3 decomposition ability on OMS catalyst surface. The two manganese-based catalysts were stable in the NTP-catalysis system although some intermediate byproducts were deposited on the catalyst surface during the 24-h activity cycling tests. Moreover, the intermediate byproducts were analyzed by GC/MS, and then the possible degradation pathways of CB decomposition in the plasma-catalysis system were suggested.