萃取精馏脱除MTBE中DMDS的分子模拟和气液相平衡研究

采用连续极化模型计算方法,对比研究了不同萃取剂与硫化物分子间的相互作用,在此基础上,通过Ellis平衡蒸馏实验测定模型硫化物二甲基二硫醚(DMDS)在甲基叔丁基醚(MTBE)和几种不同萃取剂中的气液相平衡数据,同时结合萃取剂基本性质,优选了MTBE萃取精馏脱硫适宜的萃取剂。量子化学计算结果表明,几种萃取剂与DMDS之间的相互作用由大到小的顺序为:二甲亚砜(DMSO)环丁砜(SULF)N,N-二甲基甲酰胺(DMF)N-甲基吡咯烷酮(NMP)二甘醇(DEG)。Ellis平衡蒸馏试验结果表明,各萃取剂对MTBE中DMDS的选择性由大到小的顺序为:DMSOSULFDMFNMPDEG,与量子化学计算结果相吻合,其中DMSO对DMDS的选择性最好,是MTBE萃取精馏脱硫适宜的萃取剂。此外,还建立了可用于预测不同剂油比下气液相平衡行为的经验关联式,为MTBE萃取精馏脱硫工艺设计及开发提供基础数据和理论依据。

STUDY ON MOLECULAR SIMULATION AND PHASE EQUILIBRIUM FOR REMOVING DMDS IN MTBE BY EXTRACTIVE DISTILLATION

The polarizable continuum model (PCM) calculation was used to explore the interaction between extractant and sulfide. In addition, Ellis equilibrium distillation experiments were performed for measuring the vapor-liquid equilibrium data of sulfide dimethyl disulfide (DMDS) in methyl tert-butyl ether (MTBE) and various extractants solutions. At the same time, the basic properties of extractants were measured and compared for screening the optimal solvent. The results of quantitative calculation indicate the following order of the interactions between different extractants and DMDS: dimethyl sulfoxide (DMSO) > sulfolane (SULF) > dimethyl formamide (DMF) > N-methyl-2-pyrrolidone (NMP) > diethylene glycol (DEG). The Ellis distillation experiments show the selectivity order of various extractants as: DMSO > SULF > DMF > NMP > DEG. The molecular simulation results are consistent with the experimental findings. As a result, DMSO can be considered a suitable solvent for MTBE extractive distillation desulfurization. Furthermore, an empirical correlation was built to reveal the equilibrium behaviors under different ratios of extractant/MTBE. This study can provide the necessary data and lay a theoretical foundation for the design and development of MTBE extractive distillation desulfurization process.