- 學位論文
合配體ZIF-8-90(x)/Pebax混合基質薄膜之結構與氣體分離行為之研究
The structure and gas separation behavior of ZIF-8-90(x)/Pebax mixed matrix membranes
摘要
混合基質薄膜(Mixed matrix membranes, MMMs)氣體分離的研究近年來受到相當大的矚目，無機添加物對薄膜氣體透過效能之影響，與薄膜物理化學結構和自由體積有關。本研究使用商業化之嵌段共聚物Poly(ether-block-amide), Pebax1657為基質，並使用不同比例之有機咪唑配體所合成的Zeolitic imidazolate framework-8-90(x) (x意旨ZIF-90之甲醛咪唑配體在ZIFs中所含莫爾比)為添加物，利用乾式相轉換法製備不同添加物比例的MMMs，討論薄膜氣體分離效能與MMMs各項結構特性間之相互關係。FESEM與SEM-EDX顯示ZIFs所含的有機配體能使其在薄膜中分散均勻，且與高分子之間良好貼覆。純氣體透過實驗顯示，MMMs的二氧化碳、甲烷與氮氣的透過量皆比Pebax薄膜高出兩倍以上，並且無損二氧化碳對甲烷與氮氣之氣體選擇性，在甲醛咪唑配體含量小於50%以下時，氣體透過率與ZIFs孔洞體積呈正相關；在甲醛咪唑配體含量高於50%時，薄膜二氧化碳對氮氣分離效能超越2008年的Robeson`s upper bound。研究中亦進行不同溫度之氣體透過實驗，結合恆溫吸附測試，解析溫度變化對MMMs氣體分離機制之影響。
並列摘要
The study of mixed matrix membranes (MMMs) for gas separation received considerable attention in recent years. But there are many uncertainties about the effect of inorganic additive on the gas separation performance, physical structure and the free volume of MMMs. In this study, we use the commercial block copolymer Poly(ether-block-amide) (Pebax1657) as matrix and Zeolitic imidazolate framework-8-90 (x) with different substitution content of imidazole ligand as additive. The membranes with different amount of ZIF-8-90(x) were prepared by dry phase inversion method. The relationship between gas separation performance and characteristics of MMMs was discussed in this work. FESEM and SEM-EDX showed that ZIFs with good affinity to polymer are well dispersed in the MMMs. The permeability of MMMs was two times higher than Pebax membrane and didn`t sacrificed the selectivity of CO2 to CH4 and N2. The gas permeability of MMMs are positively correlated with the pore volume of ZIF-8-90(x) when the carboxaldehyde-2-imidazole content less than 50%. The CO2-N2 separation performance is above 2008 Robeson upper bound when the carboxaldehyde-2-imidazole content higher than 50%. The effect of temperature on gas separation mechanism of MMMs was also discussed in this work.