Efficient methane conversion to methanol remains a significant challenge in chemical industry. This study investigates the direct oxidation of methane to methanol under mild conditions, employing a synergy of non-thermal plasma and Cu-MOR (Copper-Mordenite) catalysts. Catalytic tests demonstrate that the Cu-MOR IE-3 catalyst (i.e., prepared by three cycles of ion exchange) exhibits superior catalytic performance (with 51% methanol selectivity and 7.9% methane conversion). Conversely, the Cu-MOR catalysts prepared via wetness impregnation tend to over-oxidize CH 4 to CO and CO 2. Through systematic catalyst characterizations (XRD, TPR, UV-Vis, HRTEM, XPS), we elucidate that ion exchange mainly leads to the formation of zeolite-confined Cu 2+ species, while wetness impregnation predominantly results in CuO particles. Based on the catalytic performance, catalyst characterizations and in-situ FTIR spectra, we conclude that zeolite-confined Cu 2+ species serve as the active sites for plasma-catalytic direct oxidation of methane to methanol.

By combining dielectric barrier discharge plasma and external heating, we exploit a two-stage hybrid plasma-thermal system (HPTS), i.e., a plasma stage followed by a thermal stage, for direct non-oxidative coupling of CH4 to C2H4 and H2, yielding a CH4 conversion of ca. 17 %. In the two-stage HPTS, the plasma first converts CH4 into C2H6 and C3H8, which in the thermal stage leads to a high C2H4 selectivity of ca. 63 % by pyrolysis, with H2 selectivity of ca. 64 %.