关键词: 萃取, 分离, 芳烃, 相平衡, 溶剂, 选择性

Abstract: Along with more strict environmental regulations and clean fuels standards，low aromatic solvent oils should also need further dearomatization. Based on moderate operating conditions，extractant can be recycled and obtain byproduct aromatics. Lquid-liquid extraction technology is widely used，but in view of the low-aromatics raw material，extractant research and development is the key problem. A novel composite solvent adding ethylene glycol to N,N-dimethylformamide（DMF） was used as extractant in separation of low concentration aromatic solvent oil. By considering the selective coefficient（S） and distribution coefficient（K） of toluene to optimize the formulation，the mass fraction of ethylene glycol in the composite extractant was 15% ，and it was suitable for extraction separation of aromatic content less than 15% raw materials. LLE data of DMF – toluene - heptane and DMF-ethylene glycol – toluene – heptane systems were measured at atmospheric pressure and 40℃. The experimental data were correlated using the Othmer-Tobias correlation. LLE data confirmed that the composite extractant was appropriate for low-aromatic raw materials dearomatization. The optimal operating conditions of the composite extractant separating aromatics from solvent oils were determined. When extraction temperature was 40℃，extraction time was 5min，phase separation time was 10min，single stage extractant oil mass ratio was 0.5，after seven-stage counter-current extraction，the aromatics mass fraction in solvent oils was reduced from 9.15% to 0.76%.

Key words: extraction, separation, aromatics, phase equilibria, solvents, selectivity