Elsevier

Fluid Phase Equilibria

Volume 405, 15 November 2015, Pages 101-106
Fluid Phase Equilibria

Vapour–liquid equilibria of the ternary mixture (1-pentanol + 2,2,4-trimethylpentane + heptane) and the binary mixture (2,2,4-trimethylpentane + heptane) at T = 313.15 K for the characterization of second generation biofuels

https://doi.org/10.1016/j.fluid.2015.07.049Get rights and content

Highlights

  • VLE measurements are reported for the ternary mixture 1-pentanol + 2,2,4-trimethylpentane + heptane.

  • The experimental data were correlated using Wohl’s expansion, Wilson, NRTL and UNIQUAC.

  • A positive deviation from the ideal behavior without azeotrope is observed for the ternary system.

  • VLE data for 2,2,4-trimethylpentane + heptane are reported and ideal behavior is observed.

  • Good results are obtained for the prediction of the ternary systems using binary data reduction parameters.

Abstract

Accurate experimental data of vapor–liquid equilibria (VLE) are reported for the ternary system (1-pentanol + 2,2,4-trimethylpentane + heptane) and the binary system (2,2,4-trimethylpentane + heptane) at T = 313.15 K.

An isothermal total pressure cell was used for measuring the VLE. The Barker’s method for data reduction provided correlations for the excess Gibbs energy using the Margules equation for the binary system and the Wohl expansion for the ternary system. The Wilson, NRTL and UNIQUAC models were applied successfully to the binary and the ternary systems reported.

Introduction

The European target on decreasing the dependency on the petroleum is being achieved by the use of biofuels which also reduces the CO2 emissions and supports the agricultural community. The energy saving is one of the most immediate and economic way to apply energy policies that are the key of sustainability, fuel supply and competitiveness. As part of the target of the Directive «20–20–20» [1], the EU has insisted on energy efficiency with a minimum content on 10% of biofuels overall gasoline and diesel fuels.

Biofuels properties are in general different from fossil fuels, also the literature data do not have the information about the uncertainties and chemical composition lacking on metrological traceability. To facilitate wider use of biofuels in road transport, biofuels and their blends need to become increasingly compatible with existing logistics as well as future ones; but a good characterization of the thermodynamic properties is needed to obtain an in-depth understanding.

1-Pentanol is an alcohol which can be obtained from renewable sources and it is considered a second generation biofuel for gasolines [2]. Continuing with the study of the behavior of this component, the paper reports accurate experimental data of vapor–liquid equilibrium of the (1-pentanol + 2,2,4-trimethylpentane + heptane) and one of constituent binary mixtures (2,2,4-trimethylpentane + heptane). In a previous paper [3], the binary mixtures (1-pentanol + 2,2,4-trimethylpentane) and (1-pentanol + heptane) were measured.

Section snippets

Materials

The compounds were purchased from Sigma–Aldrich and were of the highest purity available, chromatography quality reagents with a purity >0.99 (GC) for 1-pentanol, >0.995 (GC) for 2,2,4-trimethylpentane and heptane. Their purities were also checked by gas chromatography and all were found to be ≥0.997. The details are summarized in Table 1.

Experimental techniques

An isothermal total pressure cell has been used for measuring the vapor–liquid equilibrium of the binary and ternary mixtures and it has been described in a

Results

The use of a static technique for measuring the equilibrium means that the vapor phase need not be sampled for analysis and the data are thermodynamically consistent “per se” [6]. Data reduction was done by Barker’s method according to well established procedures [7], [8]. The non-ideality of the vapor phase was taken into account with the virial equation of state, truncated after the second term. The pure-component and interaction second virial coefficients (Bii, Bij) were calculated by the

Discussion

For the binary system {2,2,4-trimethylpentane (1) + heptane (2)}, the two-parameter Margules equation and Wilson model give the best results of the correlation with a root mean square pressure residual of 3 Pa and a maximum deviation of 7 Pa. Good results are also obtained by NRTL and UNIQUAC models, being root mean pressure residuals of 6 Pa and 18 Pa, respectively. The pressure versus composition of both phases is plotted in Fig. 1 where it is shown that this binary system exhibits an ideal

Acknowledgments

The authors are grateful for financial support from the Spanish Minister de Science and Innovation (MICINN) for Project ENE2009-14644-C02-01 and the Project VA391A12-1 of the Junta de Castilla y León. Alejandro Moreau thanks the support from European Social Fund (ESF) and from Consejería de Educación de la Junta de Castilla y León.

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