MTN型金屬有機骨架由非序化中間體轉變為結晶態的快速途徑研究

Expressway of MTN-type metal-organic framework crystallization via amorphous intermediate

張嘉芳(Chang Jia-Fang)

指導教授 ： 林嘉和

國立臺灣師範大學/理學院/化學系/碩士(2022年)

https://doi.org/10.6345/NTNU202200155

摘要

金屬有機骨架(Metal-Organic Frameworks, MOFs)為具有結晶性與有序多孔性的材料，其結晶關鍵步驟是從溶液中形成的，儘管此步驟很重要，但 MOF 結晶的途徑一般是通過加熱混合溶液、冷卻它們然後繼續所謂的活化過程而發生，並且MOF的結晶最終狀態會影響其應用性能表現。本研究透過雙溶劑置換(two solvent exchange, TOSE)-加熱抽真空(heat under vacuum, HEVA)的方式快速驅動非序化團簇(amorphous clusters)轉變為結晶(crystalline) MOF，並延伸此一新發現，可將反應時間大幅縮短到2~4小時。
　　研究分成三個部分，在第一部分中，探討PCN-333及MIL-101兩種皆是MTN型沸石拓譜結構的MOF，在加熱反應後經由雙溶劑置換(TOSE)-加熱抽真空(HEVA)的方式誘導MOF之快速結晶化，並且透過結果展現出與原始文獻合成方式得到相似或更高的比表面積。
第二部分中，研究PCN-333及MIL-101兩個MOF在較短時間反應的最佳條件。在PCN-333系統中之MOF PCN-333-4h-HEVA具有最高比表面積4,463 m2/g，孔徑分布為39.5及48.1 Å；在MIL-101系統中MOF MIL-101(10HF)-11.1h-HEVA之具最高比表面積2,739 m2/g，孔徑分布21.3及27.4 Å。
　　第三部分中，利用粉末X光繞射儀和場發射式電子顯微鏡來觀察MOF在反應結束後溶劑清洗過程中的晶體形貌轉變，且比表面積達MOF的最佳條件。

關鍵字

金屬有機骨架材料 ； 溶劑置換 ； 加熱抽真空 ； 快速結晶化

並列摘要

The crystallization of Metal-Organic Frameworks (MOFs) from a solution is the key step to form ordering and crystalline MOF structures with porous characters. Despite their importance, the pathways through which MOFs crystallize spontaneously happen without a doubt by heating the mixture solutions, cooling them down and then continuing with so-called activation processes. And the final state of MOF crystallization will affect the performance of the applications. In this study, using a combination two solvents exchange (TOSE) and heat under vacuum (HEVA), we show that amorphous clusters rapidly transform to crystalline MOFs. And to extend this discovery, the reaction time was drastically shortened to 2 to 4 hours.
The research is divided into three parts. In the first part, the two MOFs of PCN-333 and MIL-101, both belonging to Zeolite Socony Mobil Thirty-Nine (MTN) structural types are discussed. After the heating reaction, the MOF is subjected to TOSE-HEVA. The processes raise the rapid crystallization process of MOF, and the results show that the Brunauer–Emmett–Teller (BET) specific surface area is similar or better than the original literature synthesis method.
In the second part, the best conditions for the two MOFs of PCN-333 and MIL-101 were obtained by studying the optimization of the reaction time. The MOF PCN-333-4h-HEVA in the PCN-333 system has the highest BET specific surface area of 4,453 m2/g, with pore sizes 39.5 and 48.1 Å; the MOF MIL-101(10HF)-11.1h-HEVA in the MIL-101 system has the highest BET specific surface area of 2,739 m2/g, with pore sizes 21.3 and 27.4 Å.
In the third part, we use powder X-ray diffraction (PXRD) and field emission electron microscopy (FE-SEM) to observe the crystal morphology transformation of MOF during solvent cleaning after the reaction, and when the BET specific surface area reaches the best condition.

並列關鍵字

Metal-Organic Frameworks ； solvent exchange ； heat under vacuum ； rapid crystallization

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