Degradation of toluene by DBD plasma catalytic technology with CoMn-BTC/ Ti3C2Tx composites

Dielectric barrier discharge (DBD) plasma catalytic technology is considered as one of the most effective methods for elimination of diluted volatile organic compounds (VOCs) due to its advantages of high efficiency, low cost, and wide applicability. The design of highly efficient catalytic materials is a notable challenge for this technology. In this study, Ti₃C₂T_x, GO, and NiMn₂O₄, which possess a large specific surface area and high electron transport properties, were introduced as catalyst supports. These materials were combined with CoMn-BTC to synthesize three types of supported composite catalysts, which were used for the DBD-assisted VOCs degradation. Characterization analyses, including XRD, FTIR and SEM, indicated that CoMn-BTC was successfully integrated with the three supports. The large specific surface area and more oxygen vacancy for CoMn-BTC/Ti₃C₂T_x than bulk CoMn-BTC explained the enhanced toluene removal efficiency and mineralization, CO₂ selectivity, along with suppression of undesirable O₃ and NO_x. Characterization of CoMn-BTC/Ti₃C₂T_x catalysts before and after the plasma catalytic process indicated that high adsorbed oxygen species and the redox cycles between Co^3 +/Co²⁺ and Mn²⁺/(Mn⁴⁺, Mn³⁺) species can effectively promote toluene and intermediates oxidation. Furthermore, GC-MS analysis of the organic by-products in the effluent gas revealed that the amounts of intermediates such as nitrophenol reduced in the CoMn-BTC/Ti₃C₂T_x compared with CoMn-BTC, further demonstrating that CoMn-BTC/Ti₃C₂T_x had excellent catalytic activity. At last, the possible reaction pathways of toluene degradation in plasma-catalytic system was proposed in combination with analysis results of GC-MS, optical emission spectroscopy and properties of the catalyst before and after discharge reaction.