離子液體在各類共沸物分離製程之應用

離子液體於近二十年來快速發展，離子液體可用於共沸物系統之分離，其中包含萃取蒸餾以及萃取兩大系統，但現今之研究主要著重於前段分離之好處，而鮮少討論整廠製程之模擬。本研究分成兩大部分，其一，以離子液體[EMIM][Cl]萃取蒸餾酒精與水系統，並與傳統夾帶劑甘油比較，發現離子液體於萃取蒸餾系統中即便提升相對揮發度之能力較傳統共沸劑為佳，但因為離子液體幾乎無相對揮發度之性質，反倒使得分離上會產生高溫與高熱負載，雖然以絕熱低壓驟沸分離器回收離子液體，於整廠熱負載上較甘油低9.59%，但因為於萃取蒸餾塔中需使用燃油作為熱源，較甘油使用之高壓蒸氣成本為高，且在萃取蒸餾系統中因離子液體回收須達高純度，以低壓蒸餾的方式對於降低高溫的效應不大。其二，以離子液體[EMIM][EtSO4]萃取ethyl tert-butyl ether與酒精系統，並與傳統之變壓蒸餾製程比較，發現以萃取製程無論在總年成本上與操作成本上皆較傳統之變壓蒸餾為低，且於萃取系統中離子液體回收純度並不需要太高，因此以低壓蒸餾的方式回收對於降低塔底溫度及熱負載之效應則較佳。

關鍵字

離子液體；共沸物；分離；萃取蒸餾；萃取

並列摘要

Ionic liquids started receiving closer attention in the last two decades. Ionic liquids could be used in separations of azeotropic systems, including extractive distillation and extraction; however, nowadays the research in the open literature mostly focus on the benefits of the preceding separation part, but seldom discuss the entire process design. This research is divided into two part: first part, separation of ethanol and water by extractive distillation using ionic liquid [EMIM][Cl] as entrainer. Comparing to the conventional entrainer, glycerol, although the ability to increase the relative volatility of [EMIM][Cl] is better than the glycerol, the non-volatility of ionic liquid leads to high temperature and high reboiler duty on the bottom of column. In the process, using adiabatic low pressure flash to separate ionic liquid, and the entire reboiler duty will be lower than glycerol 9.59%, but the reboiler heat source of extractive distillation column should be oil, which is more expensive than the high pressure steam of glycerol case. In extractive distillation system, the recycle ionic liquid should be in high purity, so the effectiveness of using low pressure distillation to decrease the high temperature is not good. Second part, separation of ethyl tert-butyl ether and ethanol by extraction using ionic liquid [EMIM][EtSO4] as solvent. Comparing the extraction to the pressure swing distillation, both of the total annual cost and operation cost of extraction are lower than the pressure swing distillation. On the other hand, the ionic liquid recycle flow could not reach high purity, so the low pressure distillation could decrease the high temperature and high reboiler duty effectively.

並列關鍵字

Ionic liquids ； azeotrope ； separation ； extractive distillation ； extraction

參考文獻

[1] Hurley, F. H.; Wier, T. P. Electrodeposition of Metals from Fused Quaternary Ammonium Salts. J. Electrochem. Soc. 1951, 98 (5), 203–206.

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