催化裂化轻循环油萃取脱芳烃的溶剂选择

通过分析催化裂化轻循环油（LCO）中烃类的组成筛选合适的模型化合物，考察了溶剂对LCO中芳烃组分的萃取分离效果，探讨了溶剂萃取性能与溶剂物性参数之间的关系。结果表明: 溶剂对芳烃的选择性系数从大到小的顺序为环丁砜＞二甲亚砜＞糠醛＞N,N-二甲基甲酰胺（DMF）＞N-甲基吡咯烷酮＞N,N-二甲基乙酰胺；溶剂的偶极矩和介电常数与LCO中烃类的这两个参数要有足够大的差异才能有效分离LCO中的芳烃；溶剂对芳烃的选择性系数可与其溶解度参数进行关联，对于与芳烃色散力参数δD相近的溶剂，其极性力δP越大，对芳烃的选择性系数越大；在40 ℃、剂油质量比1:1的条件下，DMF单次萃取LCO得到的抽出油中芳烃质量分数仅为87.2%，而环丁砜单次萃取时为97.3%；通过向DMF中引入助溶剂提高δP，在相同条件下萃取得到的抽出油中芳烃质量分数可达96.5%，抽出油收率为29.9%，萃取性能优于单一溶剂。

SOLVENT SELECTION FOR AROMATIC EXTRACTION FROM LIGHT CYCLE OIL

The suitable model compounds were selected base on the analysis of hydrocarbon compositions of LCO to investigate the extraction effect of solvent on aromatic compounds in LCO and the relationship between solvent extraction performance and solvent physical parameters. It was found that the order of the selectivity coefficient of the studied solvents to aromatics was sulfolane> DMSO > furfural > DMF > NMP > DMAC. The dipole moment and dielectric constant of the solvent should be sufficiently different from those of the hydrocarbons in LCO in order to effectively separate the aromatic hydrocarbons in LCO. The selectivity coefficient of solvent to aromatics can be correlated with its solubility parameter. For the solvent with δD（dispersion force parameter, one of the solubility parameters）close to that of aromatics, the larger δP (polarity force), the better the selectivity coefficient to aromatics. At 40 ℃ and oil-mass ratio 1:1, the total aromatics mass fraction in the extracted oil obtained by DMF was only 87.2% in a single pass, while that of sulfolane was 97.3%. By introducing co-solvent into DMF to enhance δP, the total aromatics mass fraction and yield of extracted oil reached 96.5% and 29.9%, respectively under the same conditions.