Desulfurization of Fuel Oil: Conductor-like Screening Model for Real Solvents Study on Capacity of Ionic Liquids for Thiophene and Dibenzothiophene

Abstract

To screen and use ionic liquids (ILs) as environmental-friendly extractive solvents in removing aromatic sulfur compounds (S-compounds) from fuel oils, the knowledge of their capacity for S-compounds (or solubility of S-compounds in ILs) is very important. In this work, the capacities of 1860 potential ILs (30 anions, 62 cations) for two representative S-compounds of thiophene (TS) and dibenzothiophene (DBT) are calculated using conductor-like screening model for real solvents (COSMO-RS). The influences of cation family, cation alkyl chain length, cation symmetry, anion nature, anion alkyl chain length, and functional group on the capacity are extensively discussed and are understood from microlevel view with σ-profile, σ-moments, and COSMO-RS energies. It is observed that the capacity is very dependent on cation and anion structure characteristics and is in a very wide range (e.g., 10–3∼101 for TS, 10–3∼102 for DBT); the van der Waals (vdW) and hydrogen-bonding (HB) energies have significant effects on t...