Elsevier

Fluid Phase Equilibria

Volume 409, 15 February 2016, Pages 327-333
Fluid Phase Equilibria

Experimental vapour–liquid equilibrium data of the quaternary system Methanol (1) + Isopropyl alcohol (2) + Water (3) + Glycerol (4) along with Isopropyl alcohol (2) + Glycerol (4) and Isopropyl alcohol (2) + Water (3) binary data at atmospheric and sub-atmospheric pressures

https://doi.org/10.1016/j.fluid.2015.09.052Get rights and content

Highlights

  • Experimental VLE data of Methanol + IPA + Water + Glycerol and IPA + Glycerol at sub and local atmospheric pressures.

  • Isopropanol + Water studied experimentally at local atmospheric pressure.

  • Isopropanol + Glycerol data correlated with Wilson, NRTL, UNIQUAC, Peng–Robinson and Soave–Redlich Kwong EoS.

  • Isopropanol + Water data correlated with Wilson and NRTL models.

  • Wilson model represents the binary systems' and quaternary system's VLE behaviour best.

Abstract

The vapour–liquid equilibrium (VLE) behaviour of the quaternary system, Methanol (1) + Isopropyl alcohol (IPA) (2) + Water (3) + Glycerol (4) at 53.33, 66.66, 79.99 and 95.2 kPa, has been studied experimentally using a Sweitoslawsky-type ebulliometer. The VLE data of this quaternary system at sub-atmospheric and ambient conditions will be useful in the process intensification design of bio-diesel production. Experimental VLE data were compared with predictions from Wilson and NRTL models using only the constituent binary interaction parameters. The predictions of equilibrium temperatures thus obtained using Wilson model compared well with the experimental values with an average root mean square deviation (rmsd T) of 0.3153 K. The binary system IPA (2) + Glycerol (4) was studied experimentally at 53.33, 66.66, 79.99 and 94.93 kPa and the data correlated with Wilson, NRTL, UNIQUAC and Peng–Robinson (PR) and Soave–Redlich-Kwong (SRK) equations of state (EoS) combined with Wong–Sandler (WS) mixing rules. Experimental data of this binary system was also compared with predictions from UNIFAC model. The VLE data of the binary system IPA (2) + Water (3) at 94.66 kPa is reported here and correlated with Wilson and NRTL activity-coefficient models. Wilson model represented the binary systems better than other models with a mean rmsd T of 0.2853 K for IPA (2) + Glycerol (4) and an rmsd T of 0.1390 for the IPA (2) + Water (3) system. MATLAB programming has been used for all the calculations.

Introduction

The experimental phase behaviour study of the quaternary system reported here, Methanol (1) + Isopropyl alcohol (IPA) (2) + Water (3) + Glycerol (4) is in continuation with our previous studies on systems found in bio-diesel processing [1], [2]. The binary systems, IPA (2) + Glycerol (4) and IPA (2) + Water (3) are constituent systems of this quaternary system and are also components of common industrial streams. IPA was chosen for this study as it is a potential key component in the production of high-value added products such as Isopropyl myristate, Isopropyl palmitate, Isopropyl oleate, linoleate etc as part of bio-diesel processing. This can be achieved through enzymatic transesterification which is a sustainable and economical green process.

The other four binary sub-systems of this quaternary system have been reported previously by the authors at atmospheric and sub-atmospheric pressures [1], [3]. The Methanol (1) + Water (3), Methanol (1) + Glycerol (4) and Water (3) + Glycerol (4) systems [1] were studied at (15.19, 29.38, 42.66, 56.03, 67.38 and 95.3) kPa, (32.02 and 45.03) kPa and (14.19, 29.38, 41.54, 54.72, 63.84 and 95.3) kPa respectively. The Wilson model was found to represent these three binary systems very well. The Methanol (1) + IPA (2) binary system was studied at (53.3, 66.7, 79.9 and 94.79) kPa and was represented best by the NRTL model [3]. Oliveira et al. [4] have reported the vapour–liquid equilibrium (VLE) data of IPA (2) + Glycerol (4) system at atmospheric pressure as part of their study of systems containing glycerol and which are part of production and down-stream processing of bio-diesel. Experimental VLE data of the IPA (2) + Water (3) binary system has been reported by many authors. In the present study, the authors found that the best-fitting model for this binary system predicts an azeotrope at the pressure studied. This is in agreement with data reported in literature [5], [6], [7], [8]. The authors did not find any experimental data in literature for the quaternary system at the pressures reported in this work.

Section snippets

Materials used

Methanol (>0.998 mol fraction, HPLC grade) provided by SD Fine Chemicals, India, IPA (>0.998 mol fraction, HPLC grade) supplied by Sigma Aldrich, glycerol (>0.995 mol fraction) provided by SD Fine Chemicals India and double-distilled water were used for experimental studies. The chemicals were passed through molecular sieves to remove any trace amounts of water and stored in dessicators prior to experimentation to prevent absorption of moisture and were used without any further purification.

Pure component vapour pressure

The Antoine constants used in the present study have been found to represent the pure component vapour pressures well over the entire pressure range of interest in our experimentation. In a previous study by the authors [15], the mean deviation between experimental vapour pressures and vapour pressures calculated using the Antoine constants from Reid et al. [16] was found to be less than 0.5% for Methanol and IPA. Pure component vapour pressures of methanol, IPA and Glycerol have been compared

Conclusions

Experimental T-x1 data of IPA (2) + Glycerol (4) binary system and Methanol (1) + IPA (2) + Water (3) + Glycerol (4) quaternary system were measured at atmospheric and sub-atmospheric pressures using a modified Sweitoslawsky ebulliometer while the binary system, IPA (2) + Water (3) was studied at the local atmospheric pressure. Experimental data of the binary systems was found to be consistent with literature data. Activity coefficient models Wilson, NRTL and UNIQUAC, group contribution method

Acknowledgements

The authors are grateful to CSIR file no. is 31/14(2547)/2013-EMRI (Council of Scientific & Industrial Research – India) for providing Research Associate fellowship to J.Soujanya.

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