Vapor–liquid equilibrium for the ternary carbon dioxide–ethanol–nonane and decane systems

doi:10.1016/j.fluid.2012.10.012

Fluid Phase Equilibria

Volume 338, 25 January 2013, Pages 30-36

https://doi.org/10.1016/j.fluid.2012.10.012 Get rights and content

Abstract

In this work, experimental vapor–liquid equilibrium (T, p, x_i, y_i) data for the ternary carbon dioxide–ethanol–nonane and carbon dioxide–ethanol–decane systems are reported in the temperature range of 313–373 K from low pressures to the nearest of the corresponding critical pressure. Measurements were performed in an apparatus based on the static-analytic method with an on-line ROLSI sampler-injector device. Vapor–liquid equilibrium (VLE) data for both ternary systems are predicted using the Peng–Robinson equation of state coupled to the Wong–Sandler, one parameter van der Waals and two parameters van der Waals mixing rules. Binary interaction parameters are obtained from the VLE data of binary mixtures reported in the literature.

Graphical abstract

Highlights

► Equilibrium (p, T, x_i, y_i) data is reported for ternary systems. ► VLE for CO₂–ethanol–nonane, and decane were measured from 313 to 373 K. ► Separation factors for ethanol over decane are higher than ethanol over nonane.

Introduction

The study of phase equilibrium behavior of multicomponent systems is necessary in order to understand and establish the temperature (T) and pressure (p) conditions where phases coexist. Thermodynamic models are used to represent the phase behavior of multicomponent mixtures; however, in some cases these models are not enough accurate and give an approximation of the phase behavior. Therefore, experimental data is the basic information that can be obtained accurately [1], [2]. Experimental methods for the determination of phase equilibrium data are classified with the aim of selecting the one suitable based on the involved phases [3], [4].

The vapor liquid equilibrium behavior for carbon dioxide + alkanol + alkane systems is scarcely available in the literature [5], [6], [7], [8], [9]. These studies are about critical end points, critical lines, miscibility windows and isothermal phase diagrams utilizing linear alkanols (pentanol to dodecanol) and alkanes (tetradecane to tetracosane). However, there is a lack of VLE data for short carbon chains of alkanes and alkanols.

As a continuation of a previous work, we present the vapor–liquid equilibrium behavior for the ternary systems carbon dioxide + ethanol + nonane or decane at three temperatures in a wide range of pressure. The experimental VLE results are compared with the prediction using the Peng–Robinson equation of state with classical and Wong–Sandler mixing rules. Separation factors between solutes are calculated from experimental vapor and liquid phase compositions.

Section snippets

Materials

Properties of chemicals [10] are listed in Table 1. Carbon dioxide of supercritical grade was supplied from Infra Air-Products. Ethanol was purchased from Merck Chemicals and alkanes were provided by Sigma–Aldrich. These were used as received with no previous purification stage. Water content was determined in a Karl–Fisher coulometer and are presented in Table 1 as well as certified purities.

Apparatus

The experimental apparatus where measurements were carried out is based on the static–analytic

Results and discussion

Liquid and vapor equilibrium phase compositions for the carbon dioxide–ethanol–nonane are listed in Table 2 at 313.33, 344.61, and 373.94 K. The corresponding data for the carbon dioxide–ethanol–decane are summarized in Table 3 at 314.98, 344.77, and 373.98 K; uncertainties in composition are also reported at each pressure in both tables based on the carbon dioxide.

Equilibrium ratios K_i = y_i/x_i for the carbon dioxide–ethanol–nonane are depicted in Fig. 1 and for the carbon dioxide–ethanol–decane in

Conclusions

Equilibrium liquid and vapor phase compositions are reported for the ternary carbon dioxide–ethanol–nonane and carbon dioxide–ethanol–decane systems at temperatures ranging from 313.33 to 373.94 K and 314.98 to 373.98 K, respectively. The Peng–Robinson equation of state using the classical (one and two parameters) and Wong–Sandler mixing rules predict acceptable deviations in pressure and composition the experimental VLE data; nevertheless, two parameter classical mixing rules have a better

Acknowledgments

Instituto Politécnico Nacional and CONACyT are acknowledged for the financial support of this research. Miguel G. Arenas-Quevedo thanks the grant provided by “Programa DELFIN” in 2011.

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Vapor–liquid equilibrium for the ternary carbon dioxide–ethanol–nonane and decane systems

Abstract

Graphical abstract

Highlights

Introduction

Section snippets

Materials

Apparatus

Results and discussion

Conclusions

Acknowledgments

Fluid Phase Equilib.

Fluid Phase Equilib.

J. Supercrit. Fluids

Fluid Phase Equilib.

Fluid Phase Equilib.

J. Chem. Thermodyn.

Fluid Phase Equilib.

J. Supercrit. Fluids

Fluid Phase Equilib.

Fluid Phase Equilib.

Gas Extraction. An Introduction to Fundamentals of Supercritical Fluids and the Application to Separation Processes