調控前驅物薄膜的厚度控制具支撐層碳分子篩薄膜氣體分離之效能

Tuning the precursor thickness to control the gas separation performance of supported carbon molecular sieve membrane

游輝敬(Hui-Ching Yu)

指導教授 ： 胡蒨傑 ； 李魁然

中原大學/工學院/化學工程研究所/碩士(2013年)

https://doi.org/10.6840/cycu201301070

摘要

本研究使用聚醯亞胺作為前驅物，藉由旋轉塗佈的方式在陶瓷基板上塗佈不同層數之前驅物薄膜，期望藉由一次的碳化程序製備出具有完整選擇層之具支撐層碳分子篩薄膜，最後藉由氣體透過效能判斷不同厚度前驅物薄膜所製備之具支撐層碳分子篩薄膜是否具有完整無缺陷的選擇層，建立前驅物厚度與薄膜氣體分離效能之關係性。
研究中先利用TGA (thermalgravimetric analysis) 鑑定前驅物高分子之熱穩定性及裂解溫度，藉此決定碳化的溫度；使用SEM (scanning electron microscopy) 觀察前驅物薄膜之厚度變化及具支撐層碳分子篩薄膜之碳化層厚度變化，並且觀察碳化後之具支撐層碳分子篩薄膜是否有缺陷生成；使用VMSPB (variable monoenergy slow positron beam) 分析具支撐層碳分子篩薄膜在不同塗佈層數與不同碳化溫度下的碳化層厚度變化對孔洞之影響；使用ATR-FTIR (attenuated total reflectance - fourier transform infrared spectroscopy) 與XPS (x-ray photoelectron spectroscopy) 分析碳化前後薄膜的化學組成差異及產碳率；並且在35℃下進行O2、N2及CO2的氣體透過測試，以關聯碳分子篩薄膜之結構與氣體分離性能之關係性。
研究結果指出，選擇層及碳化層厚度均隨塗佈層數增加而變厚，而碳化溫度愈高時，碳化層的厚度相對較薄，S parameter的結果亦顯示可關聯碳化層之厚度隨層數增加而變厚，且碳化溫度愈高孔洞結構較緻密；從ATR-FTIR與XPS的鑑定結果顯示，薄膜碳化前後前驅物的化學組成有明顯的差異，前驅物的官能基會在高溫碳化時發生裂解，並且以氣體的形式離開薄膜；氣體透過效能發現，V550與V700、V800分別在塗佈層數為2與3層時具有較完整之氣體分離效能，與前驅物薄膜相較，V550之碳膜氣體透過量大幅提升，而V700、V800之碳膜透過量及選擇比同時提升。

關鍵字

聚醯亞胺 ； 氣體分離 ； 旋轉塗佈 ； 碳分子篩薄膜

並列摘要

In this study, Polyimide was used as precursor to prepare the supported precursor membranes with different thickness by spin coating method on ceramic supports, and prepared the supported carbon molecular sieve membranes (CMSMs) by once carbonization protocols with different pyrolysis temperature. Finally, we used gas separation performance to conclude that the integrity and defect free of CMSMs.
Thermalgravimetric analysis (TGA) was used to understand the thermal stability and the pyrolysis temperature of PI precursor. The selective layer thickness of precursor and carbon layer thickness of CMSMs were observed by scanning electron microscopy (SEM). The thickness of supported CMSMs and pore property was also characterized by variable monoenergy slow positron beam (VMSPB). The chemical composition and char yield of membranes before and after carbonization were characterized by attenuated total reflectance - fourier transform infrared spectroscopy (ATR-FTIR) and x-ray photoelectron spectroscopy (XPS). Gas permeation measurement with O2, N2, CO2 were carried at 35℃.
Result show that the CMSMs were dense and defect free structure, and the thickness of selective layer of precursor membranes and CMSMs were thicker when the coating layer were increased. The S parameter result show that the carbon layer thickness were thicker after the coating layer increased, and the pore structure of carbon layer would be densification when the pyrolysis temperature was 800℃.
From the ATR-FTIR and XPS results, the chemical composition was different after carbonization. The functional groups were pyrolyzed and termed to the gases form to release from the membranes. And the char yield was increased after carbonization. Gas experimental results indicated that the gas separation performance of supported CMSMs was influenced by the precursor thickness change, and the transport mechanism of CMSMs was molecular sieving.

並列關鍵字

gas separation ； polyimide ； spin coating ； carbon molecular sieve membranes (CMSMs)

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