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为了对苯-环己烷体系进行萃取精馏溶剂的计算机筛选,采用了基于UNIFAC分子设计方法并结合Aspen数据库进行了萃取精馏溶剂的初步筛选。利用全塔模拟筛选法对初选溶剂做了进一步的筛选,获得了效果较好的一组溶剂为:含氮杂环化合物-NMP、酰胺类-DMF、醇类-四甘醇、三甘醇等。得出结论酯类和酸类分离效果一般,酯类化合物中分子链长的化合物要优于分子链短的化合物,酸类化合物则效果没有明显差异,醇类化合物除四甘醇(η_(m-n)=49.39),三甘醇(η_(m-n)=43.36),效果较好外其他醇类效果大致在20左右,分离效果一般。酮类化合物分离效果呈两端分布效果,较好的有NMP(η_(m-n)=60.876),2-NMP(η_(m-n)=43.06),其余酮类(甲基戊基酮、苯乙酮)大多不能在模拟过程中收敛,含氯化合物(1,2-二氯乙烷、1,1,2-三氯乙烷)效果最差,基本上在10以下。从分子结构和取代基方面考虑,含苯环化合物分离效果分为2种情况:苯环上有OH,COOH等取代基时分离效果较好,而苯乙烯,联苯等,烃类分离效果在15左右。另外从分子整体考虑,极性分子分离效果优于非极性分子,苯-环己烷为非极性-极性分子体系,极性分子效果较好大致上符合相似相溶的基本原理。还有10种物质在萃取精馏模拟过程中无法收敛,有待于在VLE实验过程中加以甄别。最后把模拟所得结果与“实验法”报道的结果进行了比较,具有较好的一致性。结果表明,此法方便迅捷,适用于苯-环己烷体系。
In order to screen the benzene-cyclohexane system for extractive distillation solvent, a preliminary screening of extractive distillation solvent based on UNIFAC molecular design method and Aspen database was used. Through the full tower simulation screening method, the primary solvent was further screened, and a group of solvents with good effect were obtained: nitrogen-containing heterocyclic compound -NMP, amide-DMF, alcohol-tetraethylene glycol, Wait. It was concluded that the separation of esters and acids was generally effective. Compounds with long molecular chain length in ester compounds were better than those with short molecular chains, and acid compounds had no obvious difference. The alcohol compounds except tetraethylene glycol (η_ (mn ) = 49.39), triethylene glycol (η mn = 43.36), the effect is better except for other alcohols about 20 or so, the separation effect in general. The results showed that the separation efficiency of ketones showed a two-terminal distribution with NMP (η mn = 60.876) and 2-NMP (η mn = 43.06). The remaining ketones (methyl amyl ketone, acetophenone ) Mostly failed to converge during the simulation. Chlorine-containing compounds (1,2-dichloroethane, 1,1,2-trichloroethane) had the poorest performance and were essentially below 10. From the molecular structure and substituent considerations, the separation of benzene ring containing compounds are divided into two cases: benzene ring OH, COOH and other substituents when the separation is better, and styrene, biphenyl, etc., the separation of hydrocarbons in the 15 or so. In addition, from the perspective of the molecule as a whole, the separation of polar molecules is superior to that of non-polar molecules, benzene-cyclohexane is a non-polar-polar molecular system, and the polar molecules are better in effect and basically accord with the basic principle of similar compatibility. There are 10 other substances that can not converge in the process of extractive distillation and need to be screened during the VLE experiment. Finally, the simulation results and “experimental method ” reported the results were compared, with good consistency. The results show that this method is convenient and quick, suitable for benzene - cyclohexane system.