Recent trends in developments of active metals and heterogenous materials for catalytic CO₂hydrogenation to renewable methane: A review

Carbon dioxide is a greenhouse gas that is abundantly found in the atmosphere. Therefore, by utilizing carbon dioxide to produce methane would not only reduce the concentration of greenhouse gas in the atmosphere but would also be able to partially fulfill the energy demand. This review highlights current trends in various active metals and heterogeneous catalyst supports used for thermal hydrogenation of CO2 to methane. Initially, the fundamentals, challenges and thermodynamic analysis are discussed to understand the limitations as well as the nature and thermodynamics of the possible reactions. In the mainstream, various classification of active metals, heterogeneous supports and structured materials with their role in selective methane production are discussed. In addition, various operating parameters, engineering aspects, morphologies and physiochemical properties have been thoroughly discussed on the catalytic performance and stability for the methanation reaction. The active metals as well as structure of catalyst have been reported to reduce the activation energy for the CO2 methanation, which is highly beneficial for the progression of the hydrogenation reaction. Finally, the mechanism of the hydrogenation reaction was also reviewed to determine its relationship with the catalyst active site structures.