Chapter 6 - Liquid-Liquid Equilibria for Multicomponent Systems of Imidazolium-Based Ionic Liquid + Thiophene or Pyridine + Hydrocarbon

Abstract

We now adopt a experimental strategy based on the earlier two chapters by selecting the Ionic Liquids with the anion [OAc] and [EtSO4] combined with a small cation i.e [EMIM]. The chapter then evaluates the extractive ability of these cation and anion combinations for the sulphur and nitrogen heterocycle. The extraction of benzothiophene from n-hexane is first discussed using 1-ethyl 3-methylimidazolium ethyl sulphate ([EMIM][EtSO4]) and 1-ethyl 3-methylimidazolium acetate ([EMIM][OAc]). A comparative study was done from the perspective of selectivity and distribution coefficient of the sulphur compounds. From the ternary LLE experiments, it was found that while the selectivity was higher for the ethyl sulphate-based ionic liquids, the distribution coefficient was higher for acetate based ionic liquids. Selectivities as high as 245 and 203 were obtained for [EMIM][EtSO4] and [EMIM][OAc] with negligible loss of hydrocarbon. The experimental results were correlated using the NRTL and UNIQUAC models. The quantum chemical based COSMO-RS model was then used to predict the performance of single as well as mixed ionic liquids. RMSDs of 4.36% and 7.87% were achieved for [EMIM][EtSO4] and [EMIM][OAc] based system, which are satisfactory considering that the method is a-priori. Thus this work complimented the theoretical and experimental aspects for desulphurization and denitrification studies using IL’s.