金屬有機框架結構晶體形貌與缺陷對於混合基材薄膜特性與氣體滲透之探討;Effect of Metal-Organic Framework Crystal Morphology and Defect in Resulting Mixed Matrix Membrane

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题名:	金屬有機框架結構晶體形貌與缺陷對於混合基材薄膜特性與氣體滲透之探討;Effect of Metal-Organic Framework Crystal Morphology and Defect in Resulting Mixed Matrix Membrane
作者:	吳昶諭;Wu, Chang-Yu
贡献者:	化學工程與材料工程學系
关键词:	類沸石咪唑框架配位材料(ZIF-78);有機無機複合薄膜;自由體積;氣體滲透測試;晶體形貌控制;系統性缺陷晶體;Zeolitic imidazolate framework;Mixed Matrix Membrane;Free volume;Gas separation performance;Crystal morphology control;Defective crystal
日期:	2018-07-26
上传时间:	2018-08-31 11:32:12 (UTC+8)
出版者:	國立中央大學
摘要:	文獻中，制膜溶劑、填料的形貌以及填料的特定氣體吸附能力皆是影響有機無機複合薄膜的氣體滲透效果的因素。因此，此研究高長寬比形貌以及高CO2吸附能力的ZIF-78被成功利用溶劑熱法製備。藉由使用不同製膜溶劑，系統性的製備無缺陷(No crystal cracking system)與缺陷(Crystal cracking system)的ZIF-78/PSF複合薄膜，而經由氣體滲透等一系列實驗檢測發現，ZIF-78複合薄膜擁有微孔性、高熱穩定性、膜的緻密性、以及優異的氣體滲透效能。滲透時，N2分子在路徑選擇上，傾向選擇具有較低阻力的自由體積 (填料與高分子間或是填料與填料間) 而不是透過ZIF-78的孔洞，對N2來說可以視為沒有缺陷的ZIF-78晶體與高分子鏈段形成曲折的通透路徑。相反地， ZIF-78具有硝基 (-NO2) 官能基具有較好的CO2親和力，對於CO2分子來說，較願意選擇ZIF-78 孔洞為其滲透的路徑。上述原因使無缺陷ZIF-78/PSF複合薄膜具有優異的二氧化碳對N2的選擇比。另一方面，缺陷的複合薄膜中氣體滲透的機制大多與無缺陷的複合薄膜相同，但是由於晶體裂縫而導致薄膜中自由體積 (Free volume) 的提升，自由體積的提升使在N2的通透量對比於無缺陷系統時有顯著的提升效果，同時也是造成CO2對N2的選擇比下降的原因。與過去著名的氣體分離文獻標準(Robeson upper bound in 2008) 相比，ZIF-78/PSF的複合薄膜氣體效能逼近於文獻標準。總結來說，此研究結果顯示，在ZIF-78/PSF的複合薄膜中CO2與N2具有不同的滲透路徑。我們認為，其它高長寬比形貌或是高吸附能力選擇比的材料所製成的複合薄膜也可以套用此滲透機制，將對薄膜氣體分離領域做出些許的貢獻。 ;According to literature, factors that enhance gas separation performance in MMMs include filler morphology and aspect ratio. In this work, high aspect ratio morphology and microporous ZIF-78 which have strong dipole-quadrupole interaction with carbon dioxide was successfully synthesized using a solvothermal method. ZIF-78 particles were incorporated into polymer solutions to form non-defective and systematically defective ZIF-78 filler MMMs by using two common solvents – chloroform and DMF. Characterization of the MMMs by XRD, TGA, SEM and gas transport experiments showed that MMMs had thermally stable, microporous, dense membrane phase and great gas separation performance. For nitrogen permeation, the introduction of high aspect ratio ZIF-78 crystals with no apparent defect (no cracking system) result in longer and more tortuous pathway. Conversely, for carbon dioxide, strong dipole-quadrupole interaction with ZIF-78 create excellent permeation pathway through the crystal. The defective ZIF-78 based MMMs created more inter-filler free volume which allowed the gases more chance to permeate, in addition to the original mechanism found in the no cracking system. The gas separation performance of the resulting MMMs (139% improvement of CO2 permeability and 144% improvement of CO2/N2 ideal selectivity) in this work approach the 2008 Robeson upper bound. Consequently, results showed that CO2 and N2 went through different paths during permeability test in mixed matrix membrane. We suggested that incorporating high aspect ratio particle morphology and high selectivity of gases uptake ability materials in polymer would cause special pathway to separate gases.
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