複合膜中界面聚合層的氣體分離性質

利用薄膜來進行氣體分離是一種低耗能的技術，但高選擇性的薄膜往往通量很低，高通量的薄膜選擇性又不佳，因此如何同時提高薄膜的分離效率與氣體通量一直是研究的重心。廣泛使用於製備逆滲透及奈米過濾膜的界面聚合法，可以製作出一層薄且緊密的分離層，藉由此方法，有可能得到一個高通量且高選擇性的氣體分離薄膜，但在文獻中鮮少報導。近幾年來有幾篇文獻，報告利用界面聚合法製作的複合膜來進行氣體分離，但大部分的研究都是在探討增加薄膜的含氮比例來提升二氧化碳/甲烷或是二氧化碳/氮氣的分離，卻很少關於最困難的氧/氮分離的報導。於是在這篇研究中，我們使用使用四種水相單體diethylenetriamine (DETA)，m-phenylene diamine (m-PD) ，melamine，piperazine (PIP)，兩種有機相單體1,3,5-benzenetricarbonyl chloride (TMC) ，cyanuric chloride (CC)進行界面聚合，探討單體的立體構型，反應官能基的數目，與含氮量的多寡對分離效率的影響，也探討反應時間以及單體濃度比的效應。氧/氮分離的結果發現，薄膜的含氮量與氧/氮選擇比之間關連不大，聚合時薄膜的分子交聯程度與高分子堆疊的方式應是影響選擇比的主要原因，線性以及過度網狀交聯都不利於提高選擇比，兩相單體均為平面構型且鍵結於同一平面也容易產生缺陷，兩相單體反應官能基比為3:2且其中一單體為非平面構型者，具有高選擇比與不錯的氣體通量(如：1%PIP/1%TMC具有7.72 kg h-1 m-2 atm-1的氧氣通量，0.74 kg h-1 m-2 atm-1的氮氣通量以及選擇比10.43)。增加聚合時間對氧氣、氮氣的分離效率並沒有助益，反而會因為薄膜厚度增加而減少氣體通量，而兩相單體重量百分比為1:1時所得到的薄膜，分離效率較佳。

關鍵字

氣體分離；界面聚合

並列摘要

Gas separation by membrane is an energy saving separation technology. However, high selectivity membranes are often defeated by their low permeation fluxes and high flux membranes usually suffer from their low selectivity. Therefore, how to obtain a high flux and highly selective gas separation membrane is always a major research emphasis in membrane technology. Interfacial polymerization, a technique often used in RO and NF membrane fabrication, can produce a thin and dense layer on a supporting membrane. The thin film composite (TFC) membrane by interfacial polymerization should be a good candidate of high flux and high selectivity gas separation membrane. However, limited reports mentioned about the gas separation properties of TFC membranes. Although there have emerged a couple reports in the recent year about using TFC membranes for CO2/CH4 and CO2/N2 separation. The focus was on increasing membrane polarity in order to enhancing CO2 solubility. No comments were on the structure of thin layers for gas separation, particularly on O2/N2 separation. We, therefore, tried to compare the gas separation properties of many interfacial polymerized layers by selecting 4 aqueous phase monomers: diethylenetriamine (DETA), m-phenylenediamine (mPD), melamine, and pieprazine (PIP), and 2 organic phase monomers: trimethyl chloride (TMC) and cyanuric chloride (CC). We intended to study how the shape, the number of functional groups, and the nitrogen content of monomers affect membrane performance. The effects of reaction time and monomer concentration were also under investigation. The experiment results showed that the permselectivity was not related to nitrogen content. The degree of cross-linkage and the packing of polymer chains strongly affected membrane performance. Linear polymer and over crosslinking were not favorable. Planar aqueous and organic phase monomers forming crosslinking network at the same plane created defects in the layer. We have found that the optimum ratio of reacting groups of monomers in two phases is 3:2. It could be demonstrated by the membrane synthesized by 1%PIP and 1%TMC, which had an oxygen flux of 7.72 kg h-1 m-2 atm-1 and a permselectivity of 10.43. To increase polymerization time was not beneficial to membrane selectivity. On the contrary, it decreased gas permeability by increasing membrane thickness. We also found that the 1:1 concentration ratio of monomers was required to maintain membrane selectivity.

並列關鍵字

gas separation ； interfacial polymerization

參考文獻

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[14] 王建智，製膜溶劑對聚(1-三甲基矽烷-1-丙炔)膜之氣體滲透性隨時間下降行為的影響，碩士論文，元智大學化學工程所，桃園，(2001)

[4] W. S. Winston Ho, K. K. Sirkar, Membrane Handbook, Van Nostrand Reinhold, New York, (1992).

[1] Juan Zhao, Zhi Wang, Jixiao Wang, Shichang Wang, Influence of heat-treatment on CO2 separation performance of novel fixed carrier composite membranes prepared by interfacial polymerization, J. Membr. Sci. 283 (2006) 346–356.

[2] Runhong Du, Amit Chakma, Xianshe Feng, Interfacially formed poly(N,N-dimethylaminoethyl methacrylate)/polysulfone composite membranes for CO2/N2 separation, , J. Membr. Sci. 290 (2007) 19–28.

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複合膜中界面聚合層的氣體分離性質

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