Study of Vapor–Liquid Equilibrium for the Binary Systems of (3-Buten-1-ol + n-Butanol and 3-Buten-1-ol + Water) and the Purification of 3-Buten-1-ol

Because reliable low-pressure vapor–liquid equilibrium (VLE) data for 3-buten-1-ol -containing systems are scarce and 3-buten-1-ol exhibits strong heat sensitivity. Isobaric VLE data for the 3-buten-1-ol + n-butanol and 3-buten-1-ol + water systems were measured at pressures ranging from 5 kPa to atmospheric pressure. The experimental data were correlated using the NRTL activity coefficient model, which showed satisfactory agreement with the measured results, with average root-mean-square deviations below 0.15 K in temperature and 0.005 in vapor-phase composition. The 3-buten-1-ol + n-butanol system does not form an azeotrope, and its average relative volatility increases by 26% as the pressure decreases from 101.5 to 5 kPa, indicating the potential benefit of vacuum distillation for the separation of 3-buten-1-ol from n-butanol. The 3-buten-1-ol + water system forms an azeotrope, and the 3-buten-1-ol mole fraction at the azeotropic composition decreases by 20% as the pressure decreases from 99.5 to 5 kPa, suggesting that reduced-pressure operation may facilitate 3-buten-1-ol dehydration. Residue curve maps of the 3-buten-1-ol + n-butanol + water system reveal two distillation regions. These data provide thermodynamic information for 3-buten-1-ol separation and purification.