Isobaric Vapor–Liquid Equilibrium for Binary System of <i>N</i> -Methyl-2-pyrrolidone + γ-Butyrolactone at 10.0, 20.0, and 101.3 kPa

The removal of γ-butyrolactone (GBL) from N -methyl-2-pyrrolidone (NMP) to produce electronic-grade NMP is a significant challenge to meet the rigorous purity standards of semiconductor manufacturing. Therefore, reliable thermodynamic data and models are essential for designing an intensified separation process. Herein, isobaric vapor–liquid equilibrium (VLE) data for the {NMP + GBL} binary system at 10.0, 20.0, and 101.3 kPa were determined by a Fischer Labodest VLE 602 ebulliometer. The results show that the {NMP + GBL} system is a close-boiling nonazeotropic mixture over the investigated pressure ranges. To verify the reliability of the experimental data, Herington area and Van Ness point tests used to determine the thermodynamic consistency of VLE data illustrate that all of the data have passed the test. In addition, the VLE data measured in the experiment are correlated with nonrandom two-liquid (NRTL), Wilson, and UNIQUAC activity coefficient models, and all three models show good agreement with the experimental data for this binary system. This study provides essential thermodynamic data and model parameters to support the development of purification processes for electronic-grade NMP.