Plasma-catalytic oxidation of chlorobenzene over Co-Mn/TiO2 catalyst in a dielectric barrier discharge reactor with the segmented electrodes

Abstract

Plasma-assisted catalytic oxidation of chlorinated volatile organic compounds (CVOCs) over Co-Mn/TiO2 catalyst was performed in a dielectric barrier discharge (DBD) reactor having two segmented electrodes. The combination of DBD reactor with segmented electrodes and Co-Mn/TiO2 catalyst remarkably enhanced the removal efficiency of chlorobenzene (CB) and selectivity of CO2. The segmented discharge reactor with Co-Mn/TiO2 catalyst presented the best performance with 96.3 % of removal efficiency and 69.0 % of CO2 selectivity at discharge voltage of 17 kV compared with the traditional plasma-only and other plasma-catalytic reactors. Results from discharge characteristics analysis showed that the addition of segmented electrodes and the catalysts could improve the plasma characteristics and greatly boost the specific energy density (SED) at the same voltage, resulting in the generation of more high-energy electrons and chemical active species which favor the oxidation of CB. Although the segmented electrodes facilitated the generation of O3, the Co-Mn/TiO2 catalyst boosted the decomposition of O3 to generate active oxygen species (O* and O2). The synergistic effect of introducing segmented electrodes and the Co-Mn/TiO2 catalyst into the DBD reactor at alternate voltages of 13 and 15 kV could promote the deep oxidation of intermediate products thereby bringing less effects on the catalyst surface, leading to a stable and high performance in CB removal. Furthermore, a plausible decomposition mechanism of CB destruction in the DBD reactor having segmented electrode over Co-Mn/TiO2 catalyst was proposed according to the identification of gaseous intermediates based on GC-MS analysis.