Process Simulation and Energy Assessment of CO₂ Hydrogenation to Methane

Abstract

Carbon dioxide hydrogenation to methane is a promising carbon capture and utilization pathway for producing synthetic natural gas using renewable hydrogen. In this study, a process simulation and energy assessment of CO₂ methanation based on the Sabatier reaction were carried out to evaluate the technical performance of synthetic methane production. The process was modeled by considering CO₂, H₂, CH₄, H₂O, and CO as the main components, while the effects of operating temperature, pressure, H₂/CO₂ molar ratio, water removal, and recycle configuration were systematically investigated. The Peng–Robinson equation of state was applied to describe the thermodynamic behavior of the gas-phase system. Preliminary simulation results indicated that, at 350 °C, 20 bar, and a stoichiometric H₂/CO₂ molar ratio of 4:1, the CO₂ conversion reached approximately 92.4%, while CH₄ selectivity was maintained above 98%. The energy assessment further showed that the highly exothermic methanation reaction released about 165 kJ of heat per mole of CO₂ converted, indicating significant potential for heat recovery and process integration. The reactor performance was evaluated in terms of CO₂ conversion, CH₄ selectivity, methane yield, hydrogen utilization, and energy efficiency. The proposed simulation framework enables the identification of favorable operating conditions for maximizing methane production while minimizing unreacted hydrogen and carbon monoxide formation. The results of this study can serve as a useful basis for designing integrated CO₂ capture and conversion systems and for assessing the feasibility of power-to-methane technologies under industrially relevant conditions.