Separation of polycyclic aromatic hydrocarbons by solvent screening assisted extractive distillation from FCC diesel

The oversupply of diesel in China necessitates efficient separation of polycyclic aromatic hydrocarbons from fluidized catalytic cracking diesel for value-added utilization. However, purification is hindered by alkane and monocyclic aromatic interference. In this work, we propose a solvent-screening strategy for extractive distillation based on molecular polarity and interaction energy analysis. Quantum chemical calculations identified ethylene glycol (aromatic solubility) and N , N -dimethylformamide (alkane selectivity) as optimal solvents, with weak hydrogen bonds (e.g., O-H···π, C-H···π) governing aromatic interactions. Two process designs were developed: (1) solvent extraction followed by primary extractive distillation (purity > 95.0 wt%) and (2) direct two-stage extractive distillation (purity > 92.0 wt%). This work provides a flexible framework for polycyclic aromatic hydrocarbon separation tailored to market demands while elucidating solvent-solute interactions at the molecular level.