萃取精馏分离甲醇-丁酮萃取剂的选择

Solvent Selection for Extractive Distillation Separation of the Methanol-Butanone Azeotrope System

为了解决工业生产中甲醇-丁酮共沸体系难分离的问题,本研究采用一步法合成了N-乙基吡啶溴盐([EPy][Br])、N-丁基吡啶溴盐([BPy][Br])和N-己基吡啶溴盐([HPy][Br])3种离子液体(IL),测定了101.3 k Pa下这3种离子液体对甲醇-丁酮共沸物系的溶剂选择性,并考察了溶剂比对其选择性的影响,同时将离子液体的分离性能与有机溶剂进行了比较。实验结果表明:合成的3种离子液体都可提高甲醇对丁酮的相对挥发度,它们的选择性大小顺序为[EPy][Br]>[BPy][Br]>[HPy][Br],同时,它们的选择性随溶剂比的增加而增大,与常规有机溶剂相比,离子液体作为萃取剂具有显著优势。因此,可以选用[EPy][Br]作为分离甲醇-丁酮共沸物系的萃取剂。

To separate the methanol-butanone azeotrope system in industrial production,three ionic liquids( ILs),namely,N-ethylpyridinium bromide( [EPy][Br]),N-butylpyridinium bromide( [BPy][Br]) and N-hexylpyridinium bromide( [HPy][Br]),were synthesized by one-step method and used as entrainers. The selectivities of the three ILs for the methanol-butanone azeotrope system were measured at 101. 3 k Pa,the effects of solvent ratios on their selectivities were studied,and the separation effect of ionic liquids was compared with that of organic solvents. The results showed that all the three ILs could improve the relative volatility of methanol to butanone,their selectivities followed the order: [EPy][Br]>[BPy][Br]> [HPy][Br],and their selectivities increased with increasing solvent ratios. What is more,compared with organic solvents,ionic liquids showed significant advantages as extractive solvents.Thus,[EPy][Br]can be a promising entrainer to the separation of the methanol-butanone azeotrope system.