- 學位論文
電漿輔助化學氣相沉積法製備有機矽氧烷氣體分離膜之研究
Fabrication of SiOCH Film for Gas Separation by Plasma Enhanced Chemical Vapor Deposition
摘要
本研究使用電漿輔助化學氣相沉積法以HMDSO為前驅物製備有機矽氧烷膜沉積於MCE基材上，調控單體流率、電漿功率及操作壓力等電漿參數，以期獲得分離二氧化碳與氮氣之高效能，並使用FE-SEM、SEM、ATR-FTIR、XPS及GPA等分析儀器量測其沉積膜之性質，結合其分離效能與物理、化學性質，探討其間之關聯性以了解分離效能之因素。 實驗結果發現，選擇偏向異相成核之電漿條件於基材MCE上披覆SiOCH沉積層可成功製備出分離二氧化碳與氮氣之薄膜，調控電漿參數使其分離效能提升。在調控單體流率部分，發現功率匱乏區所製備之沉積膜擁有較少之無機結構，且展現出局部分子篩之特性而與單體匱乏區所製備之沉積膜為不同類型，因此其氣體透過率與選擇比皆高。而於功率匱乏區內調控電漿功率，其分離效能與交聯度之關係密切，高電漿功率造成高交聯度與堅固的分子鏈，因此二氧化碳透過率明顯下降造成分離效能較低。操作壓力的改變對於沉積膜之化學結構變化不大，認為影響其分離效能之主要因素為離子轟擊，使得高操作壓力下擁有較好的二氧化碳透過率與分離效能。此外，亦成功地使用氬氣電漿蝕刻基材使其整體的氣體透過率提升而不影響其分離效能，增加其應用價值。本研究最佳之氣體分離效能其複合膜之二氧化碳與氮氣的氣體透過選擇比由基材之0.82提升至37.3，而二氧化碳透過率仍有150.7 GPU。
並列摘要
In this study, the plasma deposited SiOCH films onto MCE membranes were fabricated by HMDSO plasma enhanced chemical vapor deposition (PECVD). Plasma parameters (monomer flow rate, plasma power and operating pressure) were tuned to achieve high performance membranes for separation of carbon dioxide over nitrogen. Surface analysis (FE-SEM, SEM, ATR-FTIR and XPS) and gas permeability analyzer were used to elucidate the process-structure-property relationship of SiOCH films deposited in 13.56 MHz RF plasma reactor. The results revealed that the plasma parameters control the membrane’s performance. In the power deficient regime, the deposited films have less inorganic structure and show partial molecular-sieve effect, thus both the gas permeance and permselectivity of composite membranes are higher. They differ from the deposited films in monomer deficient regime where the deposited films become denser and form rigid structure with increasing power, so both the permeance and permselectivity of composite membranes are lower. The effect of operating pressure is not significant to film’s chemical structure, and the main factor affecting film deposition is ion bombardment. It leads the deposited films at high operating pressures (less ion bombardment) to show both higher permeance and permselectivity of composite membranes. Furthermore, it’s successful to enhance the permeance of composite membranes and keep the permselectivity by pre-etching MCE substrate using Ar plasma. In this study, the best performance of composite membranes is that the permselectivity increases from 0.82(MCE membrane) to 37.3 and the permeance of carbon dioxide reaches 150.7 GPU.