Perspectives on the Sustainable Steel Production Process: A Critical Review of the Carbon Dioxide (CO2) to Methane (CH4) Conversion Process

Abstract

Synthetic natural gas (SNG) can be obtained by methanation. Many thermodynamic reaction details involved in this process are not yet fully known. In this chapter, a comprehensive thermodynamic analysis of the reactions involved in the methanation of carbon oxides (CO and CO2) is carried out using the Gibbs free energy minimization method. The equilibrium constants of eight reactions involved in the methanation reactions were calculated at different temperatures. The effects of temperature, pressure, H2/CO (and H2/CO2) ration, and addition of other compounds (H2O, O2, and CH4) in the feed gas on the conversion of CO and CO2, CH4 selectivity and yield, and carbon capture were carefully studied. It was found that low temperatures, high pressure, and a large H2/CO (and H2/CO2) ratio are favorable for the methanation reactions. Concluding, the conversion of carbon dioxide (CO2) into methane could be a solution for a new technology.