Comparative Study on Thermodynamic Analysis of CO2 Utilization Reactions

Thermodynamic analysis of dimethyl ether (DME) and methane synthesis from CO2 hydrogenation, and dry reforming of methane was performed using Gibbs free energy minimization. The effects of temperature, pressure, and feed composition on conversion, selectivity, and yield were investigated for each process. High pressure, high H2/CO2 ratio, and low temperature favored DME production. The yield of methane during CO2 methanation increased at lower temperature, higher pressure, and H2/CO2 ratio. The yield of synthesis gas improved at higher temperature. Comparison of the three processes demonstrated that the CO2 conversion was highest during CO2 methanation reaction if the fraction of CO2 mol in the feed was less than 0.3. Above this value in the feed, dry reforming allowed the highest CO2 conversion.