酯化混合正丁戊醇之反應蒸餾研究

Reactive Distillation for Acetates from Butanol and Pentanol Mixtures

顏琳庭(Ling-Ting Yen)

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(2008年)

https://doi.org/10.6342/NTU.2008.01499

摘要

本研究針對混合正丁、戊醇酯化系統設計反應蒸餾系統可行性架構，並探討交錯式系統進料方式準則。熱力學方面，用NRTL-HOC model來描述塔內汽液平衡的現象；動力學方面，酯化反應採用固態酸性觸媒Amberlyst 15。混合丁、戊醇酯化系統可分為兩種程序進行探討，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」。主要針對後者做設計並提出兩種架構，（1）Direct Sequence-水從反應蒸餾塔塔頂產出，乙酸丁酯和乙酸戊酯從塔底產出的架構（2）Indirect Sequence-水和乙酸丁酯從反應蒸餾塔塔頂產出，乙酸戊酯從塔底產出的架構；其中Indirect Sequence又分為「有機相回流」和「水相回流」兩種情況。比較所有架構最適化結果得Indirect Sequence「水相回流」有較小年總成本(TAC)，其架構為反應蒸餾塔塔底產出最重之乙酸戊酯，而塔頂水相部分回流，水當挾帶劑與乙酸丁酯形成共沸物，乙酸丁酯隨著有機相從蒸餾塔塔頂流入第二根蒸餾塔並於塔底產出。
由於混合正丁、戊醇酯化系統反應物沸點排序為（丁醇<乙酸<戊醇），屬交錯式系統，此時對於混醇適合的進料位置該置於乙酸的上方或下方是值得探討的。本研究藉由探討反應動力式對進料方式的影響，得知可由醇之混合進料沸點（Tb,mix）和反應速率常數（k）判斷交錯式系統之進料方式。

關鍵字

反應蒸餾 ； 混合醇 ； 酯化反應 ； 水相回流 ； 進料位置

並列摘要

This work presents a feasible design for esterifications of n-butanol (BuOH) and n-amyl alcohol (AmOH) mixtures with acetic acid (HAc) and finds the rules of feed location for alternating system. 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. There are two alternative arrangements regarding the alcohol mixtures as feed for reactive distillation. In the first, separation of the mixture into pure alcohols goes first and esterifying with RD follows. In the second, esterification by RD directly goes first and purifying the products goes next. Two designs for products separation after the RD column are considered: (1)Direct Sequence: Reactive distillation (RD) produces water (H2O) at the top and produces butyl acetate (BuAc) and amyl acetate (AmAc) at the bottom. (2)Indirect Sequence: RD produces H2O and BuAc at the top and produces AmAc at the bottom. Besides, Indirect Sequence has two alternative flowsheets-Organic reflux and Aqueous reflux. After comparing the total annual cost (TAC), Aqueous reflux is more economical. Aqueous reflux includes a RD and a distillation column. The RD bottom obtains the heaviest product AmAc, and the top RD overhead is fed to a decanter for water separation. Part of aqueous phase as entrainer is refluxed to the RD and forms the azeotrope with BuAc. Organic phase enters to another distillation column and pure ester BuAc is obtained from the bottom.
As the boiling point of acid between the alcohols (BuOH < HAc < AmOH) is called alternating system. Feed location of alternating system is also an important issue in this study. Reaction kinetics is varied to seek the effect on the feed location. It is found that the boiling point of mixed alcohols (Tb,mix) and the reaction rate constant (k) are the important factors to be considered in determining the feed location of alternating system.

並列關鍵字

reactive distillation, alcohol mixtures ； esterification ； aqueous reflux ； feed location

參考文獻

[4] 巫衍儀，甲醇與混合酸之平行酯化反應性蒸餾系統設計與控制，國立台灣大學化學工程學研究所碩士論文(2007).

2. Al-Arfaj, M.; Luyben, W. L., “Comparison of Alternative Control Structures for an Ideal Two-Product Reactive Distillation Column,” Ind. Eng. Chem. Res., 39,3298-3307 (2000)

3. Al-Arfaj, M. A.; Luyben, W. L., “Comparative Control Study of Ideal and Methyl Acetate Reactive Distillation”, Chem. Eng. Sci., 57, 5039-5050 (2002).

4. Al-Arfaj, M. A.; Luyben, W. L., “Plantwide Control for TAME Production Using Reactive Distillation”, AIChE J., 50, 1462-1473 (2004).

5. Barbosa, D.; Doherty, M. F., “The Simple Distillation of Homogeneous Reactive Mixture”, Chem. Eng. Sci., 43, 541-550 (1988).