Research on separation of aromatics from FCC diesel using organic solvent: A combination of experiments and quantum chemical calculations

Fluid catalytic cracking (FCC) diesel is the main contributor of polycyclic aromatic hydrocarbons (PAHs) in diesel, so reducing the content of PAHs in FCC diesel is of great significance to environmental protection and high-value utilization of FCC diesel. To understand the potential separation of dicyclic aromatic from FCC diesel, dimethyl sulfoxide (DMSO), 2-methoxyethanol (EGME), and N,N-dimethylformamide (DMF) were selected as extracting solvents. The liquid-liquid phase behavior of the dodecane + 1-methylnaphthalene + solvent systems was determined to investigate the solvent extraction ability, the values of S were calculated and the high selectivity of DMSO could be confirmed. Then, the quantum chemical calculation found that the extraction mechanism of DMSO and DMF was weak H-bond and van der Waals (VDW) forces, while that of EGME was only VDW force. Additionally, the structure-activity relationship between solvent molecular structure and solvent selectivity was obtained by combining the experimental results and the quantum chemical calculations, which could provide theoretical guidance for the selection of high separation performance solvents in the future. Finally, the binary interaction parameters of NRTL and UNIQUAC models were obtained with the root-mean-square deviation (RMSD) values all less than 0.60%, which provide basic data for the further simulation of aromatics extraction of FCC diesel.