Non-Thermal Plasma Assisted Methane Reforming to Methanol over Cu-Based Catalysts

Abstract Non-thermal plasma (NTP) enables non-equilibrium activation of CH4 and CO2 under mild conditions, offering an alternative route for low-temperature gas-to-liquid conversion. In this work, methane bi-reforming (CH4/H2O/CO2 = 3 : 2 : 1) to methanol was investigated over Cu-based catalysts in a dielectric barrier discharge (DBD) reactor under three configurations: thermal catalysis (no plasma), in-plasma catalysis (IPC), and post-plasma catalysis (PPC). Experiments were conducted at atmospheric pressure with discharge power ranging from 30 to 60 W, corresponding to a specific energy input (SEI) of 15‒30 J/cm3. Discharge power was quantified using the Lissajous method. Among the tested configurations, IPC exhibited the best performance, achieving CH4 and CO2 conversions of 35 and 30%, respectively, a space-time yield of 3.6 mmol g–1 h–1, and an energy efficiency of 5.5% at SEI ≈ 22 J/cm3. In contrast, IPC showed higher conversion but lower stability and MeOH selectivity relative to PPC due to direct plasma-catalyst interaction. These results demonstrate that spatial separation of plasma and catalyst effectively enhances methanol selectivity and stability, providing design guidance for compact and decentralized plasma-assisted GTL processes.