20: Plasma-catalytic conversion of CO2-containing CH4 to oxygenated hydrocarbon products

Abstract: Catalytic valorization of CO2 containing CH4 offers a promising route to value-added oxygenated hydrocarbon products, but is limited by the thermodynamic stability of both starting compounds. Non-thermal dielectric barrier discharge (DBD) plasma paired with heterogeneous catalysis overcomes this obstacle by generating energetic electrons that activate CO2 and CH4 near ambient temperature and pressure. To this end, a series of MFI-type zeolite catalysts comprising pure silica Silicalite-1, titanium silicalite-1 (TS-1), niobium silicalite-1 (NbS-1), and gold-modified Au/TS-1 was synthesized and characterized by powder XRD, UV-Vis diffuse reflectance spectroscopy, FTIR, and Raman spectroscopy to confirm framework structure, heteroatom incorporation, and surface properties relevant to plasma-catalytic activity. These catalysts were evaluated in a DBD plasma reactor to assess their influence on CO2/CH4 co-conversion efficiency and oxygenate product distribution. Reaction products were analyzed by GC-MS to identify alcohols, aldehydes, and oxygenated compounds to evaluate catalyst performance under non-thermal plasma activation. Among the catalysts evaluated, Au/TS-1 achieved the highest fraction of oxygenate products of 71.4%, followed by NbS-1 (59.5%), TS-1 (58.3%), and Silicalite-1 (42.5%), relative to a plasma-only baseline of 47.5%, confirming that metal incorporation into the MFI framework progressively enhances oxygenate selectivity under DBD plasma activation.