Isobaric Vapor–Liquid Equilibrium Data for the Binary System of Water + 2-Methylpyridine at 101.3, 60.0, and 20.0 kPa

Isobaric vapor–liquid equilibrium (VLE) data for the binary system of water + 2-methylpyridine were determined by using Fisher VLE 602 equipment at 101.3, 60.0, and 20.0 kPa to assist with the design of the separation process by distillation. All of the binary data at different pressures were considered to be thermodynamically consistent according to Wisniak’s area and point test. The results showed that the binary system at all three pressures formed the minimum boiling azeotropes and exhibited a positive deviation from Raoult’s law. The binary VLE data were correlated by using NRTL-HOC, UNIQUAC-HOC, and Wilson-HOC models with minor deviations, and the result showed that all three models were in good agreement with the experimental data. The azeotropic temperatures and compositions at 101.3, 60.0, and 20.0 kPa were determined by the NRTL-HOC model, respectively, which showed that the azeotropic composition of 2-methylpyridine tended to decrease with the decline in system pressure.