Water sorption enhanced CO2 methanation process: Optimization of reaction conditions and study of various sorbents

Excess renewable energy can produce hydrogen and together with carbon dioxide a closed 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 degrees 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 positive effect of water sorption was proved with Zeolite 4A, La2O3 and CaO sorbents. (C) 2021 Elsevier Ltd. All rights reserved.

Automated summary

Excess renewable energy can be converted into hydrogen through methanation, forming a closed energy loop with carbon dioxide, and the efficiency of the reaction can be enhanced through in situ water sorption.