Solubility of imidazolium-based ionic liquids in model fuel hydrocarbons: A COSMO-RS and experimental study

When applying ionic liquids (ILs) in extractive and oxidative desulfurization of fuel oils, the potential solubility of IL in fuel phase is an important concern whereas research particularly on this issue is still scarce. In this work, COSMO-RS was first employed to predict the solubilities of 220 imidazolium-based ILs (11 cations and 20 anions) in 7 model fuel hydrocarbons (namely, n-hexane, n-heptane, n-octane, i-octane, cyclohexane, benzene and toluene), which cover different characters of ILs and hydrocarbons. To understand the effect of IL and hydrocarbon on the IL-in-hydrocarbon solubility, different types of molecular interactions between IL and hydrocarbon were further analyzed from COSMO-RS point of view. Finally, the solubilities of 5 representative ILs in the studied hydrocarbons were experimentally determined by nitrogen analyzer, demonstrating the good qualitative and acceptable quantitative ability of COSMO-RS for predicting IL-in-hydrocarbon solubilities.