Screening of ionic liquids for solvent-sensitive extraction -with deep desulfurization as an example

When applying ionic liquids (ILs) for solvent-sensitive extraction systems, ILs dissolved in the raffinate may lead to severe subsequent problems or a significant reduction in product quality, and thus should be particularly concerned. To screen qualified IL solvent for such systems, a rigorous criterion considering both its solubility in the raffinate and extractive ability is established. The COSMO-RS model is used to evaluate the effect of anions and cations, and suggest potential ILs meeting the criterion. Afterwards, the solubility and extractive ability of candidate ILs are investigated by experiments to further confirm their suitability. The proposed solvent screening method is exemplified for the extractive desulfurization process. [C4mim][H2PO4] is pre-selected by the screening method, and its high extractive performance is experimentally verified.