分離程序乃化工製程的重要核心部分，在分離近沸系統或共沸系統時，常以添加質量分離劑(Mass Separating Agent, MSA)的方式，來提昇系統組分之相對揮發度。 本研究乃探討使用混合溶劑(mixed solvent)的可行性及篩選方法，以環己酮/環己醇之近沸系統分離為例。利用UNIFAC、UNIFAC-DMD及COSMO-SAC等三種熱力學模式，以無限稀釋下之選擇率當作指標來進行篩選，探討使用混合溶劑的質量分離劑下造成的協同作用(Synergism)是否能改善分離程序。而其中以(DMSO/DG)之混合溶劑組合最具有發展力。 對於有發現協同作用潛力的混合溶劑系統，進行汽液相實驗以補足了該系統缺少之汽液相平衡數據，再經由NRTL模式迴歸得二元交互參數，從而進行混合溶劑(DMSO/DG)在萃取蒸餾中製程模擬與最適化。模擬結果顯示從製程經濟的角度評估，DMSO/DG莫爾添加比在1:3與1:1時的混合溶劑下之萃取蒸餾系統，其效果甚至比最佳之單一溶劑系統(DG)來得更好，亦產生了協同現象，其中以DMSO摻配比為0.5時效果最佳。並在批次蒸餾實驗中，DMSO/DG的混合溶劑添加量為30%wt時，在DMSO/DG添加比為3:1時確實產生了協同作用，與模擬的預測結果大致吻合。 Separation unit is usually the core element of a chemical process. Often to enhance the relative volatility of key components in a separation system in the presence of azeotropes or close boilers, addition of a mass separating agent (MSA) is required.Three thermodynamic models, namely UNIFAC ,UNIFAC-DMD,and COSMO-SAC, have been employed to estimate the selectivity of individual MSA candidate as a screening index. Possibility of synergistic effects for the separation of the cyclohexanol/cyclohexane system through the use of mixed solvents has been explored in the study. A mixed solvent system with DMSO and DG has shown to has such potential. Vapor-liquid equilibrium (VLE) measurements were conducted for the mixed solvent system to fill the VLE data gap. The data obtained were regressed by the NRTL model to yield binary interaction parameters, with which an extractive distillation (ED) system using the mixed solvent was simulated and optimized. Simulation results show that, in term of process economics, the optimal ED process is found when the DMSO/DG blending ratio is 1:3 or 1:1, which is even better than that of the single MSA (DG)-based ED process. With the addition of 30%wt of DMSO/DG mixed solvent (blending ratio 3:1),synergistic effect was also observed in batch distillation experiments, which also agreed well with the simulation results.
