以乙炔/氮氣電漿改質高分子氣體分離膜之研究

Gas Separation Properties of Polymeric Membranes Modified by Acetylene/Nitrogen Plasmas

施証耀(Cheng-Yao Shih)

指導教授 ： 魏大欽

中原大學/工學院/化學工程研究所/碩士(2001年)

https://doi.org/10.6840/cycu200100264

摘要

本研究以商業化之TPX膜為基材，利用乙炔/氮氣混合氣體之高週波電漿來進行表面改質，探討電漿功率、操作壓力及進料氣體流量配比等操作參數，以及添加氣體或不同沈積先驅物對膜材性質與其氧氣/氮氣分離效能之影響，並利用GPA、SEM、ATR-FTIR及XPS等分析儀器來量測電漿沈積複合膜之性質。
實驗結果發現，於基材TPX膜上所生成之電漿沈積膜，其沈積速率會隨電漿功率之增大而提高，且隨操作壓力之提高而降低，並隨乙炔進料量之增加而加快。在氧氮分離效能方面，電漿沈積膜確實能提高基材之氧氮選擇性而不至於降低太多的氧氣透過率，且其同時受到含氮官能基之親氧性及電漿沈積層之交聯度兩效應所影響；由電漿功率和操作壓力之影響來看，其分離效能僅與沈積速率及其交聯度有關；在較高的沈積速率條件下，其改質結果雖具有較佳之氧氮選擇性，但卻會因壓縮內應力的伴隨出現而導致其分離效能的喪失；根據進料氣體流量配比與不同添加氣體之探討結果，發現沈積速率愈快之情況下會加快其壓縮內應力的累積，而氮氣的加入則可以減緩壓縮內應力的累積；在表面性質分析方面，可發現於電漿沈積膜表面出現不少的含氧鍵結及微量的含氮鍵結，故導致其接觸角變小，而這表示在進料中添加氮氣的確會形成含氮鍵結，但其含量不高；此外，氮氣之加入亦會影響電漿沈積膜之交聯度。在本研究中之最佳氣體分離效能，其氧氮選擇性從基材TPX膜之3.86提升至7.55，而氧氣透過率由1.04 GPU降至0.45 GPU。

關鍵字

氣體分離 ； 氧氮選擇性 ； 表面改質 ； 電漿沈積 ； 氧氣透過率

並列摘要

In this study the plasma-polymerized films from C2H2/N2 mixtures were deposited onto the commercial TPX membranes to enhance the separation of oxygen over nitrogen. The effect of operating parameters on gas separation properties was investigated.
It was found that the deposition rate of plasma polymer increases with the plasma power and the flow rate of C2H2, and it decreases with the operating pressure. Regarding to the gas separation properties, the thin plasma polymer grown onto the TPX membrane results in a favorable increase of O2/N2 selectivity without a sharp decrease on gas permeability. The better separation performance occurred in films deposited at higher growth rates, such as pure C2H2 plasma at 60 W, or C2H2/N2 plasma at 90 W. However, the deposition time has to be short otherwise the film would lose its favorable selectivity due to film rupture induced by elevated internal stress. The internal stress in a plasma polymer was found to decrease as the feed ratio of N2 increased.
Finally, the surface structure of plasma polymer was characterized, hemispherical structures of broad size distributions was seen on the surface of the plasma polymer deposited in C2H2/N2 plasmas. The polymer deposited from C2H2/N2 plasmas contains more oxygen than nitrogen-containing functional groups. The O2/N2 separation property of TPX membrane modified by C2H2/N2 plasma is mainly determined by the degree of cross-linking in the plasma polymer, rather than the preferential sorption from different functional groups.

並列關鍵字

modification ； gas separation ； selectivity ； permeability ； plasma deposition

參考文獻

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