Thermodynamic study on binary mixtures of propyl ethanoate and an alkan-1-ol (C-2-C-4). Isobaric vapor-liquid equilibria and excess properties

This paper presents an analysis on binary mixtures of propyl ethanoate and an alkan-1-ol (ethanol to butanol) using the results obtained for different thermodynamic quantities such as the isobaric vapor-liquid equilibrium (VL E) data at pressures of 101.3 kPa and 160.0 kPa, excess enthalpies and exce ss volumes. Vapor pressures for the same normal alkanols used, determined u sing the same equilibrium still, are also presented. The three mixtures pre sent expansive and endothermic effects during the mixing process. All inves tigated mixtures show positive deviations from ideality. For two mixtures, azeotropes are found: for propyl ethanoate + ethanol, x(az) = 0.078, T-az = 351.02 K at p = 101.3 kPa, while x(az) = 0.041, T-az = 363.14 K at p = 160 .0 kPa; for propyl ethanoate + propan-1-ol, x(az) = 0.387, T-az = 367.63 K at p = 101.3 kPa, while x(az) = 0.313, T-az = 381.02 K at p = 160.0 kPa. Co rrelations of the activity coefficients, reduced excess Gibbs energy, and m ixing enthalpy using a new equation containing temperature-dependent coeffi cients were good for all three binary mixtures. The ASOG and Nitta et al. m odels yielded the best prediction of equilibrium properties for the mixture s containing ethanol while one of the modified versions of UNIFAC model gav e the best predictions of equilibrium properties for the remaining binary s ystems. Using the same set of parameters the UNIFAC and Nitta et al. models also yielded acceptable estimates of the excess enthalpies for the same mi xtures. (C) 2000 Elsevier Science B.V. All rights reserved.