Benzene removal using non-thermal plasma with CuO/AC catalyst: Reaction condition optimization and decomposition mechanism

Non-thermal plasma (NTP) technology in synergy with adsorption catalysts was used to decompose volatile organic compounds. The obtained results indicated that the non-thermal plasma-assisted catalytic system (NTP-C) resulted in higher benzene removal capability and system energy efficiency. The CuO/AC (AC: active carbon) catalysts were prepared by incipient-wetness impregnation method, and effect of CuO loading on benzene destruction was tested. The effect of reaction conditions such as inlet benzene concentration, reaction space velocity, reaction humidity and energy density were also studied. Additionally, the reaction conditions were optimized by the multi-factor orthogonal experiment, and the highest benzene removal efficiency achieved 96.5 %. The influence degree of various factors for benzene elimination was: reaction space velocity < CuO loading > energy density > inlet benzene concentration < reaction humidity. Furthermore, the benzene decomposition mechanism was discussed by analyses of the reaction exhaust, the coke substance inside the reactor, and the surface property of the used catalyst. The oxidation byproducts primarily consisted of phenol and substitutions of phenol. We propose that the radical reactions play a significant role in benzene removal on the surface of catalysts.