製程參數對碳分子篩薄膜孔洞結構 及氣體分離行為之影響

The effect of procedure parameters on pore structure and gas separation performance of carbon molecular sieve membrane

廖國淞(KUO-SUNG LIAO)

指導教授 ： 賴君義 ； 胡蒨傑

中原大學/工學院/化學工程學系/碩士(2008年)

https://doi.org/10.6840/cycu200900542

摘要

碳分子篩薄膜因其氣體分離性能優異，在近二十年被研究人員及業界投入大量的關注，其真實孔洞結構卻不甚了解。本論文以550oC及700oC兩種製程溫度，在真空環境及氮氣常壓環境兩種碳化環境下碳化先驅物薄膜，使用Steel所提出碳分子篩薄膜理想結構的概念對自行製備的平板無支撐層碳分子篩薄膜進行鑑定，並量化定出碳分子篩薄膜理想結構的兩大尺寸及一孔洞分佈：有效擴散尺寸dλ、臨界尺寸dc及斷面尺寸dTV，並與氣體分離行為關聯。本研究使用聚醯亞胺高分子薄膜做為碳膜之先驅物，發現700oC碳化的碳膜其dλ、dc較小，dTV分佈較廣，微孔孔洞數目多，導致氧/氮選擇比較550oC碳化的碳膜高，氣體透過係數較小。而氮氣碳化環境所製造的碳膜因在碳化過程沒有真空負壓的驅動力，微孔洞成長較真空環境緩慢，在氮氣550oC碳化時，其dλ、dc較真空550oC碳化環境小，dTV分佈較廣，微孔孔洞體積多，導致氧/氮選擇比較真空550oC碳化環境的碳膜高，氣體透過係數較小；氮氣700oC碳化環境碳化的碳膜，其dλ、dc較真空700oC碳化環境的碳膜大，加上微孔孔洞體積大，導致氣體透過係數較大，dTV分佈較廣，微孔孔洞體積多，吸附選擇比較高，導致氧/氮選擇比較真空550oC碳化環境的碳膜高。

關鍵字

氣體分離 ； 碳

並列摘要

In past two decades, research and industry had pay close attention to carbon molecular sieve membranes (CMSM) because the excellence gas separation performance. But it is not very bright and clear that about the CMSM physical structure. The authors designed four procedure parameters in this study : 550oC and vacuum conditions, 550oC and nitrogen condition, 700oC and vacuum conditions, 700oC and nitrogen condition. This research was aim to characterized the structure of free standing plate CMSMs with Steel’s idealy carbon molecular sieve membrane structure concept. And quantitatively determined two size and one distribution of the idealy carbon molecular sieve membrane structure : effective diffusion jump length dimension (dλ), critical dimension (dC), transverse dimension (dTV). Correlated with the different carbonization conditions CMSM pore structure ans gas separation performance.
The precursors of carbon membranes is polyimide membranes. The dλ and dC of 700oC carbonized CMSM was less than 550oC carbonized CMSM and the dTV of 700oC CMSM was broad and more pore volume. Lead to the O2/N2 selectivity of 700oC CMSM was higher than 550oC CMSM, but the permeability. The nitrogen condition carbonized CMSM didn’t have the driving force of negative pressure, the
carbonization rate and pore formation was slow than vacuum conditions. When 550 oC nitrogen condition, the dλ and dC was less than 550 oC vacuum condition, dTV was broad and pore volume was higher. Lead to O2/N2 selectivity of 550oC nitrogen condition CMSM was higher than 550oC vacuum condition CMSM but the permeability. When the 700oC nitrogen condition CMSM, the dλ and dC was higher than 700 oC vacuum condition, and the dTV was broad and pore volume was higher, so that the permeability of 700oC nitrogen condition CMSM was higher than 700 oC vacuum condition one. dTV of 700oC nitrogen condition CMSM was broader than 700oC vacuum condition CMSM ones. So that the O2/N2 selectivity of 700oC nitrogen condition CMSM was higher.

並列關鍵字

carbon molecular sieve membranes

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