Greenhouse gas CO 2 hydrogenation to fuels: A thermodynamic analysis

Over the past few years, chemical conversion of CO 2 to alternative fuels such as methanol, dimethyl ether (DME), and hydrocarbons (HCs) is one of the hot topics in chemical engineering. Taking this into consideration, we have investigated the effects of wide range of temperature, pressure and H 2 /CO 2 ratio (with and without CO) on the hydrogenation of CO 2 to methanol, DME, and HCs by minimizing the Gibbs free energy. The energy calculations indicate that HC synthesis reaction has the minimum Gibbs free energy change. High pressure, low temperature, and high H 2 /CO 2 ratio favored the methanol and DME synthesis. The HC synthesis is favored by high pressure, low temperature, and high H 2 /CO 2 ratio, but the presence of CO has a major effect on the HC selectivity. The presence of CO suppresses CO 2 conversion in all the three reactions studied. CO 2 conversion is maximum for the HC synthesis at H 2 /CO 2 > 3. The experimental data obtained from laboratory scale fixed bed reactor show a reasonable comparison with the simulation results. The thermodynamic analysis combined with the catalyst development and chemical kinetics are expected to lead towards a competent methodology for CO 2 conversion. © 2018 American Institute of Chemical Engineers Environ Prog, 38: 98–111, 2019