Water Sorption Enhanced Co2 Methanation Process: Optimization Of Reaction Conditions And Study Of Various Sorbents

Abstract Excess renewable energy can produce hydrogen and together with carbon dioxide a close energy loop can be formed through methanation (Power to Gas), which can be enhanced by in situ water sorption. Sorption causes a shift in equilibrium to favor methane production, while also decreasing secondary reactions and allowing operation at lower temperatures. In order to get suitable conditions for water sorption operating parameters were adjusted. The optimum temperature was 290 °C, avoiding high temperatures inside the catalytic bed due to the high exothermicity of the methanation; moreover, 15 bar of total pressure, 1.4 g catalyst and intermediate feedflows were found the best ones to obtain conversion close to equilibrium without external mass transfer resistance. The achieved hydrogen conversion was 92-94 % with high selectivity, as no CO was detected and methane yield matched hydrogen conversion. The possitive effect of water sorption was proved with Zeolite 4A, La2O3 and CaO sorbents.