Steam Stripping-Coupled Cycle for Thermodynamic Optimization and Carbon Cycle Intensification in CO/CO₂ Mixed-Gas Hydrogenation Methanol Synthesis

Methanol synthesis, a crucial platform chemical and clean energy carrier, plays a significant role in the global energy transition. This study focuses on thermodynamic optimization and carbon cycle intensification of the CO/CO₂ hydrogenation process. A multidimensional reaction system model was developed to investigate the effects of the CO/CO₂ feed ratio, H₂/CO _<i>x</i> molar ratio, reaction temperature and pressure, catalyst efficiency, and gas-liquid mass transfer resistance on product distribution. To improve carbon utilization, an innovative steam stripping-coupled cycle process was proposed, enabling efficient recovery of dissolved CO₂ in the liquid phase through phase equilibrium regulation. This reduced the CO₂ content from 10.72 kmol·h^-1 before stripping to 1.69 × 10^-4 kmol·h^-1 after stripping. Under optimized operating conditions, the methanol yield reached 82.0%, and the single-pass yields of CO and CO₂ were 90.7% and 72.6%, respectively. After the novel stripping cycle was adopted, the loss of liquid-phase CO₂ became negligible, with carbon and hydrogen losses mainly caused by gas-phase relaxation. When the relaxation rate was set to 1.0%, the utilization of CO _<i>x</i> and H₂ reached 93.2% and 82.8%, respectively. This strategy established a dynamic reaction-separation-recycle balance, improving both resource efficiency and economic performance, and offering theoretical and technical guidance for green methanol industrialization.