Simultaneous desulfurization and dearomatization of simulated straight-run diesel with novel green DBN-based ionic liquids

Given the surplus of diesel fuel in China and the extensive utilization of renewable energy sources, there is a growing inclination to eliminate organic sulphur and aromatic hydrocarbons from diesel fuel for its application as high-quality ethylene cracking feedstock. In this study, a series of 1,5-diazabicyclo[4.3.0]non-5-ene (DBN)-based ionic liquids with [DBNH]+ as the cation and imidazole as the anion were designed and synthesized for the simultaneous desulfurization and dearomatization of straight-run diesel fuel. Considering factors such as extractant stability, residue content in oil, and separation performance, [DBNH][Tr], exhibiting excellent performance characteristics, was screened as the optimal extractant. Following three-stage cross-flow extraction with an extractant/oil ratio of 3:1 at 30 °C, complete removals of sulfides (benzothiophene) and polycyclic aromatic hydrocarbons (1-methylnaphthalene) were achieved while saturated alkanes reached up to 95.8 wt%, making it suitable for ethylene cracking applications. The interaction mechanisms between ionic liquids and oil components were revealed by atoms in molecules (AIM) topology analysis, independent gradient model based on Hirshfeld partition (IGMH) analysis, and symmetric adaptive perturbation theory energy decomposition techniques, revealing that dispersion-dominated van der Waals (VDW) forces primarily govern interactions due to π-π stacking.