Recent Trends in Plasma-Assisted CO2 Methanation: A Critical Review of Recent Studies

In recent years, enormous efforts have been devoted to alleviating global energy demand and the climate crisis. This has instigated the search for alternative energy sources with a reduced carbon footprint. Catalytic hydrogenation of CO₂ to CH₄, known as the methanation reaction, is a pathway to utilise CO₂ and renewable hydrogen simultaneously. However, owing to the high stability of CO₂ and thermodynamic limitations at higher temperatures, the methanation process is energy intensive. Non-thermal plasma technology has recently emerged as a promising approach to lowering the activation temperature of CO₂. The application of a plasma coupled with catalytic materials allows the methanation reaction to occur at or near ambient conditions, with dielectric barrier discharges providing superior performance. The review considers the various catalytic materials applied for plasma-assisted catalytic CO₂ methanation and assesses CO₂ conversion, CH₄ yield and fuel production efficiency obtained. The importance of reactor designs and process parameters are discussed in detail. The possible reaction pathways are considered based on in-situ and other diagnostics and modelling studies. Finally, a perspective on current barriers and opportunities for advances in non-thermal plasma technology for CO₂ methanation is presented.