Research On Liquid Liquid Equilibrium For Separating Azeotropic Systems Of Dimethyl Carbonate With Low Carbon Alcohols By Deep Eutectic Solvents

Dimethyl carbonate(DMC)is a kind of chemical raw material and product with wide use and excellent performance.However,dimethyl carbonate will form azeotropic systems with low-carbon alcohols(such as methanol and ethanol)in the process of industrial production.Traditional methods for separating dimethyl carbonate-methanol and dimethyl carbonate-ethanol azeotropes are difficult to obtain good separation results.Therefore,we adopt a more economical,effective and convenient method to separate the two azeotropes by deep eutectic solvents in this work.In this work,choline chloride was chosen as hydrogen bond acceptor based on the conductor like screening segment activity coefficient(COSMO-SAC)model.For hydrogen bond donors,glycerol,ethylene glycol,urea and malonic acid with wide range of application and low price were selected as hydrogen bond donors.Therefore,choline chloride and glycerol,choline chloride and ethylene glycol,choline chloride and urea,choline chloride and malonic acid were prepared in the molar ratio of 1:2 as the extractant in this work.In this work,the liquid liquid equilibrium(LLE)data of two ternary systems:dimethyl carbonate-methanol-deep eutectic solvents and dimethyl carbonate-ethanol-deep eutectic solvents were measured at 298.15 K and 308.15 K at atmospheric pressure.The distribution coefficients and selection factors were calculated,the results show that the selected four deep eutectic solvents have a good extraction efficiency.The high reliability of the experimental data were tested by Hand equation and Other-Tobias equation.Also,the NRTL activity coefficient model was used to correlate the experimental data,the binary interaction parameters are obtained,the values of root mean square deviation(RMSD)between the correlated and experimental values were calculated,the results show that the NRTL model can well correlate the experimental data of the ternary systems with high accuracy.Finally,the integrity of the composition of the selected deep eutectic solvents before and after extraction was proved by1H NMR.