Thermodynamic analysis of methane synthesis by hydrogenation of carbon dioxide

In this study, a thermodynamic analysis of methane synthesis by hydrogenation of carbon dioxide was performed. Although the standard Gibbs potential of this reaction, known as the Sabatier reaction, is negative, methane synthesis under standard conditions does not occur due to kinetic limitations. To overcome these kinetic limitations, a significant increase in temperature and pressure is necessary along with a catalyst additive. Therefore, further thermodynamic analysis of the Sabatier reaction was carried out for the real conditions of this reaction, temperature Tr = 673.15 K and pressure Pr = 3 MPa. The calculations showed that under real conditions the Sabatier reaction has exothermic enthalpy ΔrH = -181 kJ/ mol, and negative Gibbs potential ΔrG = -84 kJ/mol. Thus, methane synthesis reaction from carbon dioxide and hydrogen at elevated temperature Tr and pressure Pr is energetically and thermodynamically favorable. In addition, the equilibrium constant of this reaction Keq is 3.24 x 106. This great value of the Keq indicates that under real conditions the Sabatier reaction is strongly shifted to the methane synthesis.