以滲透蒸發及萃取蒸餾分離碳酸二甲酯及甲醇共沸物之設計

碳酸二甲酯(DMC)是一種綠色材料，廣泛應用於化學和石化業，因而吸引越來越多的關注。碳酸二甲酯的生產過程中，經常伴隨著甲醇/碳酸二甲酯共沸物之分離問題。滲透蒸發能夠不受熱力學液氣平衡限制而分離共沸物，因此本研究嘗試以滲透蒸發與既有之碳酸二甲酯生產製程做結合，並以年總成本作為評估標準探討透過滲透蒸發改進原有製程之可能性。在滲透蒸發的模擬部分，本研究以實驗文獻提供之通量數據做為建立擴散係數參數之根據，並討論優先選擇甲醇與優先選擇碳酸二甲酯兩種不同的情況。受限於現有之薄膜的分離能力，滲透蒸發難以在碳酸二甲酯製程中作為最後一步分離，本研究將滲透蒸發作為萃取分離的前處理系統，在滲透蒸發的部分選擇不同的溫度及總分離面積組合成四種狀況，截留產物進入到萃取蒸餾塔後完成萃取分離系統的最佳化搜尋，最後發現滲透蒸發系統應操作在高溫並減少分離所需之總膜面積，而當膜材之價格低於$300/m2，滲透蒸發將更佳具備有改進碳酸二甲酯生產製程的效益。

關鍵字

滲透蒸發；萃取蒸餾；混合程序；碳酸二甲酯

並列摘要

Dimethyl carbonate (DMC) as a “green” material has been increasingly gaining popularity because of its wide application in chemical and petrochemical industries. Purification is an important step in the DMC synthesis process as the DMC obtained in the reactive distillation column is usually an azeotropic mixture with methanol. Pervaporation (PV) is suitable for the separation of azeotropic mixtures. It is not limited by the vapor-liquid equilibria. In this study, the hybrid PV with existing DMC production process is studied, and the total annual cost as the evaluation criteria would be discussed to see if it is possible to improve the process. To simulate DMC in the PV process, the parameters of the diffusion model are estimated through the flux experimental data obtained from two kinds of membranes in literature. Limited by the existing membrane separation capacity, only the PV separation is too difficult to get the required purity of DMC, so in this study, the PV separation is used as a pre-extraction treatment system. Four conditions with different combinations of temperatures and membrane sizes are selected in the PV separation; then the PV-extraction system is optimally designed on the basis of the total annual cost. It is found that in the PV system, the higher operating temperature and the smaller membrane areas would be more cost saving. Also, at the membrane price less than $300/m2, the hybrid PV with the extraction system for the purification DMC would be more cost-saving than the extraction system only.

並列關鍵字

Pervaporation ； Extractive distillation ； Hybrid process ； Dimethyl carbontate

參考文獻

[1]Amornchai, A.; Ukrit, S.; Yaneeporn, P.; Futtichai, A. “Hybrid Process of Reactive Distillation and Pervaporation for the Production of Tert-amyl Ethyl Ether.” Chinese Journal of Chemical Engineering. 2008, 16, 100-103.

[2]Amte, V. “Optimization of Hybrid Reactive Distillation-Pervaporation System.” 21st European Symposium on Computer Aided Process Engineering-Escape 21. 2011.

[4]Buchaly, C.; Kreis, P.; Gorak, A. “Hybrid Separation Processes-Combination of Reactive Distillation with Membrane Separation.” Chemical Engineering & Processing. 2007, 46, 790.

[5]Chen, J.-H.; Liu, Q.-L.; Fang, J.; Zhu, A.-M.; Zhang, Q.-G. “Composite Hybrid Membrane of Chitosan-Silica in Pervaporation Separation of MeOH/DMC Mixtures.” Journal of Colloid & Interface Science. 2007, 316, 580-588.

[6]Csefalvay, E.; Szitkai, Z.; Mizsey, P.; Fonyo, Z. ”Experimental Data Based Modeling and Simulation of Isopropanol Dehydration by Pervaporation.” Desalination. 2008, 229, 94-108.

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以滲透蒸發及萃取蒸餾分離碳酸二甲酯及甲醇共沸物之設計

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