Thermodynamics and modeling of efficient MAE-TGBE-H2O phase-separating CO2 absorbents

Phase-separating absorbents show promise for reducing energy consumption, as desorption requires heating only the CO 2 -enriched phase. This study investigates triethylene glycol monobutyl ether (TGBE) as a phase-separation promoter for the N-methylaminoethanol (MAE)–water system. The role of TGBE in restructuring hydrogen-bond networks and promoting rich-phase aggregation was analyzed using gas–liquid–liquid equilibrium, 13 C NMR, gas chromatography, and molecular dynamics (MD) simulations. Experimental results demonstrate that TGBE significantly reduces rich-phase volume while achieving CO 2 equilibrium loadings of 3.59 mol/kg for water-containing systems and 4.73 mol/kg for water-free systems. MD simulations reveal that CO 2 absorption redistributes intermolecular interactions, where strengthened hydrogen bonds between water and ionic species drive polar rich-phase aggregation. Furthermore, an empirical model, a GBDT-based predictive model, and a modified Deshmukh–Mather framework were developed to describe phase behavior with AARDs of 2.81%, 4.58%, and 6.61%, respectively. These findings provide a theoretical foundation for designing energy-efficient CO 2 capture systems.