以ZSM-5沸石掺杂改性的1,4-双(4-氨基-2-三氟甲基-苯氧基)苯-1,2,3,4-环丁烷四甲酸二酐型聚酰亚胺为前驱体,通过旋涂成膜和热解过程制备了平板状支撑炭膜.采用热失重、红外光谱、X射线衍射、扫描电镜及气体渗透技术分别研究了前驱体热稳定性、膜表面官能团、微结构,微观形貌及分离性能.考察了ZSM-5掺杂量及热解温度对炭膜结构和气体分离性的影响.结果表明:经ZSM-5改性后前驱体热稳定性与残炭量降低,炭膜微观结构变致密;加入沸石显著提高了炭膜的渗透性,且随ZSM-5掺杂量增加,气体渗透性先减小后增大;随着热解温度升高,炭膜的渗透性与选择性皆减小.经650℃热解制得杂化炭膜对H2/N2体系的分离性能均远超过Robeson上界限.
Plate supported carbon membranes were prepared by precursor of 1, 4-bis(4-amino-2-trifluoromethylp-henoxy) benzene-1, 2, 3, 4-cyclobutanetetracar-boxylic dianhydride type polyimide modified with zeolite ZSM-5, through the processes of spin-coating and pyrolysis. Thermal stability of precursor, surface functional groups, micro-structure, morphology, and separation performance of membranes were characterized by the techniques of thermo-gravimetric analysis, infrared spectroscopy, X-ray diffraction, scanning electron microscope, and gas permeation, respectively. Effects of incorporating amount of ZSM-5 and pyrolysis temperature on structure and gas separation performance of carbon membranes were investigated. Results show that thermal stability and carbon residue of pre-cursor are reduced by ZSM-5 modification. Simultaneously, the microstructure of carbon membranes becomes more compact. Incorporation of zeolite remarkably increases the gas permeability of carbon membranes. In addition, the gas permeability first decreases then increases with increased incorporation of ZSM-5. As the pyrolysis temperature elevating, both permeability and selectivity of as-obtained carbon membranes decrease. The separation performance performance of hybrid carbon membranes prepared at pyrolysis temperature of 650℃ is by far the Robeson's upper bound for H2/N2 system.
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