Extractive Distillation of Benzene and Cyclohexane by Using 1-propyronitrile- 3-butylimidazolium dicyanamide

Due to very close boiling point of benzene and cyclohexane (~Tb = 0.6°C),
separation of them is one of the most challenging processes in the chemical industry
and it is not practical to separate such a binary mixture by conventional distillation
process. The separation efficiency of ionic liquid as a solvent in the extractive
distillation process, COSMO-RS generated the information of potentially applicable
ionic liquid of 1-propyronitrile-3-butylimidazolium dicyanamide [C2CNBim]N(CN)2
with aromatic compound and aliphatic compound is studied at temperature range
(293.15 to 323.15) K and at atmospheric pressure. Firstly, the ionic liquid is
synthesized and its property measurements is characterized. Then study on
thermophysical properties of ionic liquid is done by preparing 1-propyronitrile-3-
butylimidazolium dicyanamide added with benzene at different compositions and
their density and refractive indices are measured at the stated temperature and
pressure. Thermal expansion coefficients are estimated using the measured density
values. Secondly, headspace-gas chromatography (HSGC) experiments are done at
the stated conditions to calculate the relative volatility of the sytstem by measuring
and observing vapor-liquid equilibrium (VLE) data for the ternary systems
(benzene+cyclohexane) with the ionic liquid. So far there is no available
thermophysical data of 1-propyronitrile-3-butylimidazolium dicyanamide with
aromatic compound yet and there is no available data on relative volatility of this
ionic liquid with benzene and cyclohexane. All of these reasons have given me the
motivation to carry out this study.