This paper investigates the degradation of chlorobenzene by dielectric barrier discharge (DBD) coupled with MnO x /γ-Al 2 O 3 catalysts. MnO x /γ-Al 2 O 3 catalysts were prepared using the impregnation method and were characterized in detail by N 2 adsorption/desorption, x-ray diffraction and x-ray photoelectron spectroscopy. Compared with the single DBD reactor, the coupled reactor has a better performance on the removal rate of chlorobenzene, the selectivity of CO x , and the inhibition of ozone production, especially at low discharge voltages. The degradation rate of chlorobenzene and selectivity of CO x can reach 96.3% and 53.0%, respectively, at the specific energy density of 1350 J l -1 . Moreover, the ozone concentration produced by the discharge is significantly reduced because the MnO x /Al 2 O 3 catalysts contribute to the decomposition of ozone to form oxygen atoms for the oxidation of chlorobenzene. In addition, based on analysis of the byproducts, the decomposition mechanism of chlorobenzene in the coupled reactor is also discussed.

The effects of using CH4 as an assistant reduction agent in plasma-assisted NH3–SCR were investigated. The new hybrid reaction system performed better than DBD–NH3–SCR when the O2 concentration varied from 2% to 12%. Compared with DBD–NH3–SCR, DBD–NH3–CH4–SCR (NH3:CH4 = 1:1) showed a more significant promotion effect on the performance and N2 selectivity for NOX abatement. When the O2 concentration was 6% and the SIE was 512 J/L, the NO removal efficiency of the new hybrid system reached 84.5%. The outlet gas components were observed via FTIR to reveal the decomposition process and its mechanism. This work indicated that CH4, as an assistant agent, enhances DBD–NH3–SCR in excess oxygen to achieve a new process with significantly higher activity at a low temperature (≤348 K) for NOX removal.

In this special issue, we only investigated the compare of two type DBD reactors (CC-DBD and TM-DBD). However, further studies are required about the mathematic relation between electrode structure parameters (electrode length, discharge gap and so on) and electron energy. It is important for industrial application of DBD to understand the effect of O 2 content for NO x removal because O 2 usually exist in industrial waste gas. The research for electron energy of DBD by using VSim is an effective way, while relevant studies are rare. DBD technologies are paid considerable attention by many scientists and I think the research results in the paper would provide helpful information for the future investigation in the relevant research filed.