The dry methane reforming process holds the potential to convert the greenhouse gas carbon dioxide into highvalue-added fuels and chemicals, presenting broad application prospects in the fields of environmental protection and renewable energy. In this study, a two-stage pulsed discharge cold plasma reactor was experimentally investigated at ambient temperature and atmospheric pressure. The primary products of this process were syngas (CO and H₂), with smaller quantities of C₂Hᵧ compounds (y = 2, 4, or 6) also produced as by-products. This research aims to examine and compare a single-stage plasma system with a two-stage system. The results demonstrate that a significant improvement in methane conversion and hydrogen selectivity is achieved when the plasma energy is discharged across two stages. This performance enhancement is attributed to the presence of hydrogen generated in the second plasma stage. These findings indicate that plasma power alone is not the sole factor determining optimal performance; rather, the method of its delivery can profoundly influence the conversion of methane and carbon dioxide, product yields, and energy conversion efficiency. In this configuration, the hydrogen produced in the first stage promotes the generation of radicals in the second stage, consequently increasing both conversion rates and energy efficiency despite the constant total plasma energy input. Another contributing factor to the performance improvement is that a larger, more homogeneous gas volume is exposed to the pulsed discharge in the second plasma stage, which can lead to an increased effective gas residence time within the plasma.
