Experimental analysis of vapour-liquid phase equilibria for binary systems of diethyl carbonate with methyl, ethyl, isopropyl, n-butyl and isoamyl acetates at 95 kPa

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Highlights

  • Vapor-liquid phase equilibrium behaviour is analyzed experimentally for five pairs of diethyl carbonate with esters.

  • Vapor-liquid equilibrium (VLE) data is generated at local atmospheric pressure in the form of T-x,y plots.

  • Thermodynamic consistency of the data is checked to confirm suitability of the data for process modelling applications.

Abstract

Experimental analysis of vapour-liquid phase equilibrium (VLE) for five binary pairs of diethyl carbonate (DEC) with methyl acetate, ethyl acetate, isopropyl acetate, n-butyl acetate and isoamyl acetate was carried out in this study. VLE data were generated experimentally at local atmospheric pressure of 95 kPa in a glass dynamic recirculation still. Reliability of data was checked with the thermodynamic consistency tests by Van Ness, infinite dilution, pure component and mean absolute deviation test. Experimental data was found to be thermodynamically consistent with all tests and data was regressed with Wilson, NRTL and UNIQUAC activity coefficient models to determine binary interaction parameters. Binary pair of DEC with n-butyl acetate has shown azeotropic behaviour with minimum boiling azeotrope and a close-boiling behaviour through-out the composition range. No azeotropic behaviour was observed for the rest of the binary pairs.

Introduction

Increasing air pollution problems because of deficient ignition of fuel can be overcome using certain additive which helps in complete combustion of fuels. Gasoline additives especially oxygenate help to get high octane fuel. [1], [2] Among oxygenates, dimethyl carbonate (DMC) and diethyl carbonate (DEC) contains higher concentration of oxygen (53.3 wt% and 40.7 wt%, respectively). [3] DEC is also considered as a green chemical and has received much attention in recent years. DEC finds numerous applications in chemical industry. It is used as a raw material for polycarbonate production and also finds application as intermediate for agrochemicals, pharmaceutical and dye industry. DEC has found as major fuel additive because of its high oxygen content and complete combustion. Both DMC and DEC are biodegradable, DMC decompose to CO2 and methanol whereas DEC decompose to CO2 and ethanol. [4], [5] DEC can be synthesized from the reaction of ethanol with carbon dioxide. [6] Application of DEC as an entrainer for extractive distillation is also reported for separation of azeotropic systems such as cyclohexane-cyclohexene. [7] VLE data for DMC with various acetate is already available in literature. [8] VLE data for few binary pairs of acetates with DEC is reported in the literature. [9], [10], [11]

In the present work, isobaric VLE data for binary systems, DEC + methyl acetate, DEC + ethyl acetate, DEC + isopropyl acetate, DEC + n-butyl acetate, DEC + isoamyl acetate has been determined experimentally at local atmospheric pressure of 95 kPa. Interaction parameters were determined for various activity coefficient models which can be used for mathematical modelling and designing various unit operations and processes involving mixtures of DEC and esters.

Section snippets

Chemicals

All the chemicals were available from Loba Chemie of analytical grade. Purity of chemicals was confirmed by measuring refractive index from Atago (RX-7000i) (accuracy of ± 0.0001 and resolution 0.00001) at 298.15 K. The chemicals were directly used without further purification. Details of chemicals used are given in Table 1. Table 2 contains the reported and experimental refractive index (nD) and boiling points (Tb).

Apparatus and procedure

Dynamic recirculation type glass VLE apparatus proposed by Mali et al. [18] was

Experimental VLE data

The vapour–liquid equilibrium (VLE) data for binary pairs methyl acetate + DEC, ethyl acetate + DEC, isopropyl acetate + DEC, n-butyl acetate + DEC, isoamyl acetate + DEC was measured isobarically at local atmospheric pressure of 95 kPa. Experimental VLE data for these systems is given in Table 3, Table 4, Table 5, Table 6, Table 7. The corresponding T-x,y plots are as shown in Fig. 1, Fig. 2, Fig. 3, Fig 4, Fig. 5. Experimental relative volatility and calculated relative volatility using

Conclusion

In this work experimental isobaric vapour-liquid equilibrium data was generated for pairs methyl acetate + DEC, ethyl acetate + DEC, isopropyl acetate + DEC, n-butyl acetate + DEC, isoamyl acetate + DEC, at constant local atmospheric pressure of 95 kPa in the form of T-x,y. T-x,y plots show that the pair of DEC with n-butyl acetate forms a minimum boiling azeotrope at 0.48 DEC mole fraction and 394.6 K. The pair n-butyl acetate-DEC was also found to be close-boiling throughout the composition

CRediT authorship contribution statement

Bharat R. Bhoi: Investigation, Writing - original draft, Formal analysis, Visualization. Nilesh A. Mali: Conceptualization, Methodology, Supervision, Writing - review & editing. Sunil S. Joshi: Resources, Funding acquisition.

Declaration of Competing Interest

The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.

Acknowledgement

The Authors are thankful to CSIR-National Chemical Laboratory, Pune (Maharashtra), India for supporting the present work.

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