Isobaric Vapor-Liquid Equilibrium for Systems of Propylene Glycol Monomethyl Ether, Cyclopentanone, N -Methylpyrrolidone at 101.33 kPa

Abstract The thin-film release solution for photoresists, formulated with propylene glycol methyl ether (PM) and cyclopentanone (CPO), is widely used in semiconductor processes; however, it is difficult to separate due to concentration-dependent effects. This research focused on examining the vapor–liquid phase equilibria of three binary mixtures composed of the extractive distillation entrainer N-methylpyrrolidone (NMP) and the close-boiling components─propylene glycol monomethyl ether (PM) or cyclopentanone (CPO)─namely, the NMP–PM, NMP–CPO, and CPO–PM systems. In contrast, the intermolecular interactions between NMP and PM are stronger than those in the other two systems. Furthermore, the relative volatility of CPO compared to PM is also influenced by NMP. The experimental data have demonstrated excellent thermodynamic consistency upon verification. A regression analysis of binary-system vapor-liquid equilibrium data was conducted using the Wilson, NRTL, and UNIQUAC models, with the UNIQUAC model demonstrating superior predictive performance. At solvent molar fractions of 0.7, 0.8, and 0.9, employing the UNIQUAC model, compositional impacts on PM/CPO relative volatility were evaluated to estimate the minimum equilibrium stages necessary for effective distillative separation. This research has demonstrated the feasibility and effectiveness of using NMP for extraction and distillation separation of PM/CPO at both experimental and theoretical levels.