Highly efficient extractive desulfurization by specific functionalized porous ionic liquids via C-H···π interactions

Porous ionic liquids (PILs) are an emerging class of materials that possess the porosity of solids and the fluidity of liquids, which have shown great potential in separation. Herein, a novel kind of silica-based porous ionic liquids (OS-PIL) functionalized with quaternary ammonium salt was successfully synthesized to remove the dibenzothiophene (DBT) in the model fuel. The OS-PIL exhibit high extraction activity and its Nernst partition coefficient could reach up to 4.22. The experimental results indicated that a synergistic effect between porous materials and ionic liquids as well as the multiple sites in quaternary ammonium salt greatly contributed to the high extractive desulfurization efficiency. Moreover, density functional theory (DFT) calculations and spectroscopic investigations were employed to gain in-depth insights into the extraction mechanism. The results demonstrated that the porous structure and ion pair of OS-PIL exhibit stronger interaction for DBT, in which the C-H···π is dominant. These kinds of PILs with highly specific surface areas and multiple active sites will have good application prospects in the field of extractive desulfurization.