Mesoporous topology-regulated plasma-catalytic CH₄-CO₂ reforming for greenhouse gas valorization

Mitigating greenhouse gas emissions from CH₄ and CO₂ while simultaneously converting them into value-added chemicals represents an important pathway toward sustainable carbon management. Ni-based catalysts show considerable potential in non-thermal plasma-catalytic CH₄-CO₂ reforming. However, the influence of support topology on plasma-catalyst interactions and catalytic performance remains insufficiently understood. In this study, Ni/SBA-15 and Ni/KIT-6 with different mesoporous topologies were comparatively investigated in terms of discharge characteristics, physicochemical properties, and catalytic performance under various operating conditions. The results showed that Ni/SBA-15 outperformed Ni/KIT-6, exhibiting higher CH₄ and CO₂ conversions, syngas yields, and energy efficiency. Under a discharge power of 25 W, a gas flow rate of 60 mL min^-1, and a CH₄/CO₂ molar ratio of 1:5, the CH₄ and CO₂ conversion rates reached 48.4% and 23.0%, respectively, with CO and H₂ yields of 17.3% and 19.5%, and an energy efficiency of 0.45 mmol kJ^-1. In addition, Ni/SBA-15 showed lower selectivity toward gaseous hydrocarbons but higher selectivity toward oxygenated products (30.7%). The superior performance of Ni/SBA-15 was associated with its more favorable mesoporous topology, which retained a higher accessible surface area after Ni loading and provided a higher concentration of surface oxygen-related defect sites, a greater abundance of Lewis acid sites, and stronger basicity than Ni/KIT-6. Combined spectroscopic evidence and product analysis suggested that these features contributed to the more effective regulation of CH₄- and CO₂-derived reactive species and surface intermediates at the plasma-catalyst interface. These findings provide useful insight into the design of efficient plasma-catalytic systems for greenhouse gas valorization.