Intensified Separation of Propylene Glycol Monomethyl Ether/Acetic Acid/Water Azeotropes from Computational Thermodynamics to Process Design

The PM/AcOH/water ternary azeotropic system, as a typical nonideal system, has dual value in achieving propylene glycol methyl ether acetate clean production. This study develops a multiscale collaborative screening methodology for an entrainer through the COSMO-RS-based screening of 240 ionic liquids and quantum chemical calculations. The feasibility of using [DMIM][NTF2] in conjunction with NMP as a mixed entrainer for ED separation of PM/AcOH/water was confirmed through TGA analysis, viscosity testing, and structural characterization. The process design adopts a multiobjective optimization framework (NSGA-II algorithm) to compare the single/mixed entrainer ED process under normal and pressure swing conditions and innovatively couples intermediate heat exchange and heat integration process enhancement strategies; a multiobjective optimized process (P-ILs-MED) was established. The results indicate that this hybrid entrainer and pressure swing strategy demonstrates superior economic performance, significantly reducing exergy loss by 43.87% compared to the conventional process and by 50.26% versus the base ILs-MED process, providing an industrially viable pathway for waste liquid treatment and high-purity azeotrope separation.