Isobaric Vapor–Liquid Equilibrium (VLE) of 3-Ethoxypropionitrile and Adiponitrile

Isobaric vapor–liquid equilibrium (VLE) data for a mixture of 3-ethoxypropionitrile and adiponitrile were obtained at 2, 7, 14, and 20 kPa using a modified Rose–Williams still. The instrument’s reliability was confirmed by measuring the vapor pressures of 3-ethoxypropionitrile and adiponitrile at various temperatures. The consistency of the VLE data was evaluated using methods proposed by Wisniak and Fredenslund. Five activity coefficient models (Margules, van Laar, NRTL, Wilson, and UNIQUAC) were used to correlate the VLE data, and the excess Gibbs free energy of the mixture was calculated. Parameters for these models were determined from experimental data, and the regression results were evaluated using the root mean square error for temperature (RMST) and the root mean square error for vapor phase mole fraction (RMSy1). The Margules model showed higher temperature deviation than others, while the Wilson, NRTL, and UNIQUAC models performed well for this system. Additionally, the NRTL model demonstrated superior predictive accuracy among the tested models, with RMST and RMSy1 values below 0.9 and 0.005, respectively.