混合乙、異丙醇之反應蒸餾酯化研究

Reactive Distillation for Acetates from Ethanol and Iso-propanol Mixtures

江明璟(Ming-Ching Chiang)

指導教授 ： 黃孝平

國立臺灣大學/工學院/化學工程學研究所/碩士(2010年)

https://doi.org/10.6342/NTU.2010.02059

摘要

本研究針對混合乙、異丙醇系統，研討利用反應蒸餾設計酯化反應之可行性架構。熱力學方面，用Hayden-O’Connell以及NRTL model來描述塔內汽液平衡的現象；動力學方面，酯化反應均採用固態酸性觸媒Amberlyst 15，並且修改Calvar針對乙醇的酯化反應動力式之前置項。混合乙、異丙醇酯化系統可分為兩種程式進行探討，分別是「先分離醇進料，後酯化反應」和「先酯化反應，後分離產物」。比較所有架構最適化結果得「先酯化反應，後分離產物」有較小年總成本(TAC)。其架構為封住反應蒸餾塔塔底，而使用分相槽有機相部分回流，並將混合之乙酸乙酯、乙酸異丙酯隨著有機相從反應蒸餾塔塔頂流入第二根蒸餾塔於塔底產出。而塔頂產物則回流到分相槽以增加反應物的轉化率。最後，再使用一根蒸餾塔來分離純化乙酸乙酯、乙酸異丙酯。
根據乙醇和異丙醇的混醇酯化系統進一步設計分隔內壁蒸餾塔改善其能耗以及成本問題。顯示反應性分隔內壁蒸餾塔有其發展潛力。根據研究結果，其節能來源是消除了反應蒸餾塔底的再混合效應。

關鍵字

反應蒸餾 ； 混合醇 ； 酯化反應 ； 分隔內壁蒸餾塔

並列摘要

This work presents a feasible design for conducting esterifications of ethanol (EtOH) and iso-propyl alcohol (IPOH) mixtures with acetic acid (HAc). The NRTL-HOC thermodynamic models are used for modeling the vapor-liquid and vapor-liquid-liquid equilibrium. The reactions are catalyzed by using Amberlyst-15 catalyst. Furthermore, the Pre-exponential factors of esterification of ethanol based on Calvar is modified. There are two alternative arrangements regarding the alcohol mixtures as feed for reactive distillation. In the first, separation of the mixture to pure alcohols goes before esterifying with RD. In the second, esterification by RD goes directly before purifying the products. According to the boiling point ranking and the phase equilibrium data, conceptual process design is proposed. Aspen Plus simulator is then used to find an optimal flow sheet with a minimum total annual cost for each of the two arrangements above mentioned. After comparing the total annual cost (TAC), the second arrangement turns out to haves more economical benefit than the first one. The second arrangement includes a RD and close the exit on the bottom of RD. And use a decanter in order to separate water from organic phase. Part of organic phase stream will go back into the RD. The organic phase then is feed into a stripper to obtain EtAc and IPAc mixtures on the bottom of stripper. Overhead vapors of the stripper recycle to the decanter in order to increase the conversion for reactant. In the end, we use a distillation column to separate ester mixtures.
Although the resulting optimal process can achieve high product specifications, heat integration needs to be considered for reducing the energy cost and the total annual cost. To decrease the energy consumption and capital cost, the separation columns in the above process is integrated to a DWC configuration. By simulation, compared with the original design, in this DWC design, all energy required is provided by the reboiler of the distillation column. To make this major saving possible, this DWC indeed avoids the remixing effect that used to take place is the original stripper bottom.

並列關鍵字

reactive distillation ； alcohol mixtures ； esterification ； DWC

參考文獻

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