THEORETICAL STUDY ON INTERACTION BETWEEN IONIC LIQUIDS AND AROMATIC SULFUR COMPOUNDS

It is important to understand how ionic liquids interact with aromatic sulfur compounds in view of ionic liquids application in desulfurization from fuels. Ion pairs of N, N-dialkylimidazolium dialkylphosphate ionic liquids were optimized at the Becke3LYP level of density functional theory. The most stable geometries were obtained. The stable ion pairs indicate there exist hydrogen bonding interactions between them. The calculated interaction energies of ion pairs were found to increase in magnitude with decreasing alkyl chain length, and with decreasing anionic radius. Furthermore, the interactions between the IL and aromatic sulfur compound, and benzene molecule were investigated. The results indicate that there exist hydrogen bonds between them. The calculated interaction energy between IL and sulfur compound is larger than that between IL and benzene. The aromatic ring pi - pi interaction and hydrogen bonding interaction may be the dominant factors to influence the trend of interaction between ILs and aromatic sulfur compounds.