| Summary: | 碩士 === 中山醫學大學 === 職業安全衛生學系碩士班 === 100 === In general, carbon materials with a very narrow micropore distribution below 5 A makes possible to separate gas pairs with very similar molecular dimensions via molecular sieving mechanism, such as H2 (2.8 A), CO2 (3.3 A), O2 (3.46 A), N2 (3.64 A) and CH4 (3.8 A). Therefore, to obtain the carbon molecular sieve membrane (CMSM) with ultra-microporous structure, pyrolysis of polymer precursor becomes a main preparation procedure.
However, the selective layer (carbon) cannot be bond well to the Al2O3 support due to the different properties between them. In general, After the composite polymer membrane were formed by the spin coating procedure, there exist interfacial stresses between polymer and support, which builds up and finally are relaxed by forming interfacial gap due to the shrinkage of organic phase during the carbonization process. Thus, in this project, the effect of support physic-chemical characterization on the texture and the gas separation performance of the CMS membrane were investigated.
In this research, alumina disk was selected as substrate material; it’s porous structure, surface roughness and chemical functional groups was modified with different sintering conditions and MFI silica. The characterization of support materials and CMS membrane were investigated by TGA, FTIR, XRD, BET, AFM and SEM.
The results indicated that the CMSM supported on S1400-2-2 substrate shows the best separation performance with PH2= 1300 Barrer [1 Barrer = 1x10-10 cm3 (STP) cm/(cm2 s cmHg)], αH2/CH4 = 174. After modification with MFI silica, the CMSM supported on 1100-MFI-1 substrate shows better H2 permeability of 2223 Barrer and an ideal H2/CH4 selectivity of 260 due to the crosslinking reaction between polymer chain and Si-O, Si-O-Si groups. The results indicated that the permselectivity of carbon molecular sieving (CMS) membrane fabricated in this study can exceed the 2008 Robeson’s trade-off line.
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