| Summary: | A plasma–catalyst hybrid system has been developed for the direct conversion of methane to C<sub>2+</sub> hydrocarbons in dielectric barrier discharge (DBD) plasma. TiO<sub>2</sub> presented the highest C<sub>2+</sub> yield of 11.63% among different dielectric materials when integrated with DBD plasma, which made us concentrate on the TiO<sub>2</sub>-based catalyst. It was demonstrated that MnTi catalyst showed the best methane coupling performance of 27.29% C<sub>2+</sub> yield with 150 V applied voltage, without additional thermal input. The catalytic performance of MnTi catalyst under various operation parameters was further carried out, and different techniques, such as X-ray diffraction, X-ray photoelectron spectroscopy, transmission electron microscopy, and H<sub>2</sub>-temperature-programmed reduction were used to explore the effect of Mn loading on methane oxidative coupling (OCM) performance. The results showed that applied voltage and flow rate had a significant effect on methane activation. The dielectric particles of TiO<sub>2</sub> loaded with Mn not only synergistically affected the coupling reaction, but also facilitated charge deposition to generate a strong local electric field to activate methane. The synergy effects boosted the OCM performance and the C<sub>2+</sub> yield became 1.25 times higher than that of the undoped TiO<sub>2</sub> under identical operating conditions in plasma, which was almost impossible to occur even at 850 °C on the MnTi catalyst in the absence of plasma. Moreover, the reaction activity of the catalyst was fully recovered by plasma regeneration at 300 °C and maintained its stability in for at least 30 consecutive cyclic redox tests. This work presents a new opportunity for efficient methane conversion to produce C<sub>2+</sub> at low temperatures by plasma assistance.
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