Comparison of Hydrogen Reduction Technologies for the Effective Purification of CO 2 Methanation Product Gas Through Process Simulation

Methane production through CO2 methanation has gained considerable interest as a measure to achieve carbon neutrality in city gas. High methane purity is required to use the gas produced by methanation as city gas, and the residual hydrogen from the raw material must be reduced. Technical difficulties and high costs are problematic despite the purity of methane being improved by lowering the reaction temperature through improved catalyst activity or increasing the pressure of the process. Methods utilized to achieve high methane purity through process improvements include a trim methanator with water separation in the system, ethanol dehydration–hydrogenation reaction, and selective oxidation of hydrogen. In this study, these effective processes for hydrogen reduction were compared, specific reactor configurations that consider the risk of carbon deposition and heat transfer were proposed, and the cold gas and overall efficiencies were calculated. Consequently, ethanol dehydration–hydrogenation and selective oxidation of hydrogen were utilized to produce high-purity methane with high efficiency through a simple process.