由於醋酸和正丁醇會起酯化反應，產生水和醋酸正丁酯，若僅以兩成份系統之汽液相平衡數據來考慮此混合物的相平衡，與實際的情形有所出入。本研究將直接考慮醋酸-正丁醇-水-醋酸正丁酯四成份系統的汽液相平衡行為，讓反應平衡和汽液相平衡均達到之後，再進行濃度分析。 實驗係以改良Othmer的汽液平衡裝置進行相平衡數據的量測，並在系統中加入觸媒(對甲苯磺酸)以縮短化學反應平衡所需的時間，並收集了41點的實驗數據。 在結果與討論中分別以實驗數據來迴歸UNIQUAC及NRTL兩種液相活性係數模式的參數，汽相考慮有強結合效應，並且比較關聯結果和實驗數據的差異。由結果顯示，UNIQUAC和NRTL二種液相模式所得之關聯結果都不錯，但又以UNIQUAC較好一點。最後以UNIQUAC模式來計算液相活性係數，繪出此四成份系統的反應相圖，並由相圖中判斷此四成份系統在伴隨反應的情形下，不會出現共沸點。 The aim of this study will probe into the thermodynamic behavior of acetic acid, n-butanol, water and n-butyl acetate mixture. Because the influence of chemical reaction on the distillation process can't be neglected, both the phase equilibrium and the chemical reaction equilibrium must be concerned. The experiments of chemical equilibrium and phase equilibrium were conducted in a modified Othmer type equilibrium cell. The catalyst(p-toluenesulfonic acid) was added to increase chemical reaction rate, and found no effect on the phase equilibrium. 41 experimental data were collected for this study. The experimental VLE data were correlated by activity coefficient models of UNIQUAC and NRTL, respectively, with consideration of the strongly association of acetic acid moleculars in vapor phase. Our calculated results show that the correlation by UNIQUAC model was in good agreement with the experimental data. It is also found that the reactive azeotrope does not exist in this study by using Barbosa and Doherty’s criterion of a reactive system.
