Methane conversion by a plasma-assisted process: Role of hybrid plasma–thermal configurations in controlling conversion pathways

Producing carbon-neutral H2 and C2–C3 hydrocarbons from methane using renewable energy is an important route toward cleaner fuels and chemicals. Here, we analyze a non-thermal plasma-assisted hybrid process for converting methane into H2, C2–C3 hydrocarbons, and value-added carbon by combining methane cracking with nonoxidative methane coupling. The process employs a thermally assisted atmospheric-pressure plasma jet, offering potential advantages in terms of operational simplicity, reduced costs, and scalability. We developed and compared different hybrid plasma–thermal configurations. Positioning the plasma directly within the heated zone enhances plasma–thermal cooperation, resulting in a fivefold increase in methane conversion and the lowest carbon deposition (around 36%) over the investigated temperature range. The recovered carbon exhibited turbostratic nanostructural features, as demonstrated by combined characterization techniques, as required for “quality” carbon materials to be valorized as advanced materials. Controlled plasma–thermal coupling can tune methane conversion pathways, enabling flexible coproduction of hydrogen, hydrocarbons, and valuable solid carbon.