Choline chloride based deep eutectic solvents selection and liquid-liquid equilibrium for separation of dimethyl carbonate and ethanol

Dimethyl carbonate (DMC) is an excellent gasoline and diesel additive in the field of fuel. However, it can form azeotrope with ethanol, so separation of DMC with high purity from the azeotrope is of significance. To separate the azeotrope of DMC and ethanol, the σ-profiles were calculated by the COSMO-SAC model to determine suitable deep eutectic solvents (DESs). On the basis of σ-profiles analysis, four choline chloride based DESs were selected and evaluated as extractant. The liquid−liquid equilibrium (LLE) data for the ternary systems DMC + ethanol + DESs were determined at T/K = 298.15 and 308.15 K under 101.3 kPa. The distribution coefficient and selectivity were calculated to evaluate the extraction ability of the DESs. And the influence of different temperature on phase behavior was explored. In addition, the 1H NMR spectrums of the DESs distributed in the upper and lower phases were obtained to check the integrity of the DESs. Meanwhile, the LLE experimental data were correlated by the NRTL model, the correlation results show an agreement with the experimental data.