Comparative investigation of CO2-to-methanol process using different CO2 capture technologies

CO2-to-methanol can realize the emissions reduction and resource utilization of CO2. However, CO2 capture technology will lead to energy and economic penalties of the whole methanol production process. Thus, the effect of different CO2 capture technologies on the performance of the whole methanol production process is analyzed and compared in this study. A rigorous steady-state modeling and simulation of the four different CO2 capture technologies (monoethanolamine (MEA), phase-change separation (PCS), dimethyl carbonate (DMC), and gas membrane separation (GMS)) are conducted, and the results are validated with literature data. Accordingly, the technical, economic, and environmental performances of the CO2-to-methanol process under different CO2 capture technologies are analyzed to explore the low-carbon, efficient, and economically optimal carbon capture technology for green methanol synthesis. The results showed that the energy efficiency of the GMS case was the highest (68.4%), followed by PCS (66.2%), DMC (64.3%), and MEA (61.3%). The total production cost of the GMS case was the highest (4367 CNY/t-CH3OH), followed by MEA (4314 CNY/t-CH3OH), DMC (4279 CNY/t-CH3OH), and PCS (4204 CNY/t-CH3OH). All four cases achieved CO2 emissions reductions. With the development of the third generation of biphasic absorbents, the PCS case improved the energy efficiency by 78.6%–83.8%. Thus, the PCS case was the optimal technology choice for achieving low-carbon, efficient, economic trade-offs in the commercial methanol production based on CO2 capture and utilization.