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Measurements and Correlations of the Isobaric Vapor–Liquid Equilibria of Binary Mixtures and Excess Properties for Mixtures Containing an Alkyl (Methyl, Ethyl) Butanoate with an Alkane (Heptane, Nonane) at 101.3 kPa

2012; American Chemical Society; Volume: 57; Issue: 11 Linguagem: Inglês

10.1021/je300799f

1520-5134

Raúl Ríos, Juan Ortega, Luís Fernández,

Chemical Thermodynamics and Molecular Structure

In this work, the measurements of the isobaric vapor–liquid equilibrium (VLE) data at 101.32 kPa and the excess molar volumes (vE), obtained at 10 K intervals of temperature in the range (288.15 to 328.15) K, for four binary systems comprised of methyl or ethyl butanoate with two alkanes (heptane and nonane) are presented. The vE are positive for the four mixtures, and their variation with temperature presents a thermal coefficient (∂vE/∂T)p > 0, and the behavior of these systems is interpreted. Experimental VLE data (p,T,x,y), obtained in a small capacity ebulliometer, present a positive consistency according to the method of Fredenslund. The methyl butanoate + heptane system presents a minimum boiling-temperature azeotrope with the following coordinates at the working pressure: (x1,az = 0.404; Taz = 367.65 K). Measurements of (T,pio) are also shown for all of the compounds and were determined using the same equilibrium equipment. Experimental data are correlated with an appropriate polynomial model proposed by the authors. A simultaneous correlation is performed for the characteristic VLE properties and the hE values taken from the literature. For the correlation of properties of methyl butanoate + heptane system, values of cpE from the literature were included in the correlation process. In all cases the multiproperty goodness of fit is acceptable. Another correlation procedure by successive steps in the order (x,cpE)→(x,hE)→(x,gE) is also applied when the experimental data exist for the binaries studied; the results obtained with both procedures are similar. The universal functional activity coefficient (UNIFAC) method is applied to estimate the VLE values, hE and cpE, with different results. The VLE prediction is acceptable in all cases except for the methyl butanoate + heptane mixture, although the estimation of the other thermodynamic quantities is not adequate.