Plasma-catalytic reforming of CH4-CO2 over porous Ni/N-doped carbon: Efficient syngas production and mechanistic insights

Abstract

The integration of non-thermal plasma and catalysis offers a promising route for low-temperature reforming of methane (CH4) and carbon dioxide (CO2) into high-value syngas (H2 and CO), enabling efficient activation of stable molecules and tunable product selectivity. However, limitations in energy efficiency, selectivity control, and catalyst dura-bility remain. In this study, a water-cooled dielectric barrier discharge (DBD) reactor cou-pled with a porous nitrogen-doped carbon-supported nickel catalyst (Ni/N–C) was developed to enhance CH4–CO2 reforming performance. The results showed that increasing the CH4/CO2 molar ratio significantly enhanced both reactant conversion and syngas selectivity, while a higher gas flow rate adversely affected conversion efficiency. Under optimal condi-tions (60 mL/min gas flow rate, 1:5 molar ratio of CH4/CO2), CH4 and CO2 conversions reached 44.1% and 20.0%, with CO and H2 selectivities of 67.6% and 48.1%, respectively. The corresponding energy efficiency was 0.39 mmol/kJ. Mechanistic insights derived from catalyst characterization and performance analysis revealed that moderate acid sites pro-moted CH4 activation and facilitated the selective formation of C2 hydrocarbons, while abundant basic sites enhanced CO2 adsorption and activation, thereby improving CO and H2 selectivity. The synergistic effect of acid–base site modulation and plasma-driven activation played a key role in steering the reaction pathway and optimizing product distribution. This work highlighted the potential of tailored Ni-based catalysts for efficient and selective plasma-catalytic reforming of CH4 and CO2 into syngas. Keywords: CH4-CO2 reforming; Non-thermal plasma; Nitrogen-doped carbon; Syngas