Vapor-liquid equilibria for binary systems composed of a propyl ester (ethanoate, propanoate, butanoate) plus an n-alkane (C-7, C-9)

This paper reports isobaric vapor-liquid equilibrium measurements made usin g a small equilibrium still at a pressure of 101.32 kPa and other excess pr operties for a set of six binary mixtures composed of one of three propyl e sters (ethanoate, propanoate, butanoate) and one of two n-alkanes (heptane, nonane). The vapor pressures for the n-alkanes measured using the same equ ilibrium still and the correlations calculated are also presented. Applicat ion of the point-to-point test showed the systems studied to be consistent. All the data were correlated, and processing of the equilibrium data inclu ded the excess enthalpies. The system consisting of propyl ethanoate + hept ane has an azeotrope at x(az) = 0.423, T-az = 366.9 K, and the system consi sting of propyl butanoate + nonane has an azeotrope at x(az) = 0.726, T-az = 414.4 K. Both the modified-UNIFAC theoretical model and the Nitta model y ield acceptable estimates of the different properties for these propyl este r + n-alkane mixtures.