Coupled CO2 absorption and phase separation with precise phase regulation on biphasic absorbent

Liquid–liquid phase separation is an interesting phenomenon that generates two immiscible liquid phases during CO 2 absorption or temperature swing. It provides a promising opportunity to optimize CO 2 capture processes and reduce the energy penalty for solvent regeneration. However, precise control of phase behavior remains challenging. This work achieves controllable phase separation in amine-ether-water systems. Results show that adjusting the ether-to-water mass ratio enables the correlation between critical CO 2 loading and temperature to reversibly shift from negative to positive. This rule is verified in various amines and ethers. Synergistic effects of temperature and CO 2 absorption on phase separation are revealed by 13 C NMR and molecular dynamics simulations. This study deepens the understanding of phase separation and offers a theoretical basis for developing high-performance CO 2 absorbents for industrial applications.