A seeded growth procedure was used to successfully prepare continuous and well inter-grown zeolitic imi-dazolate framework-8 (ZIF-8) membranes on porous α-alumina tubes. The effects of some parameters including the content of seeds and PEI in seeding solution, the concentration of sodium formate in synthesis solution and synthesis temperature on the formation of ZIF-8 membrancs were invcstigated in detail. The characterization of SEM, XRD and single gas permeation showed that PEI added in the seeding solution can improve the adhesion between the seed crystals and the support surface. Moreover, sodium formate used in synthesis solution could prevent the seed layer from peeling off during the membrane growing process. The as-synthesized ZIF-8 membrane is well inter-grown and continuous. Single gas permeation shows that the separation factors of H2/CO2 and H2/CH4 are 5.4 and 2.56, respectively, indicating that Knudsen diffusion plays a controlling role in the gas permeation through the ZIF-8 membrane.%以纳米级ZIF-8晶体粒子为晶种,利用晶种诱导二次生长法在α-Al2O3陶瓷管载体上制备出连续的ZIF-8膜,并详细考察了晶种涂层液中晶种含量、成膜温度和添加剂PEI、甲酸钠用量等参数对ZIF-8成膜的调控影响.经SEM、XRD和气体渗透分析结果表明:制备的ZIF-8纳米粒子的粒径约为100～150 nm,粒度分布较均匀,适宜作为成膜的晶种;在晶种液中添加适量的PEI作为偶联剂有利于连续ZIF-8晶种层及膜的形成;在成膜液中添加适量的甲酸钠能有效阻止载体表面晶种层的溶解脱落.SEM显示所得ZIF-8膜的晶体粒径均一、晶粒间连接紧密且无明显裂痕,膜层厚度约为18 μm.单组分气体渗透测试可知,H2/CO2的分离因数为5.4,H2/CH4的分离因数为2.56,气体通过ZIF-8膜均属于努森扩散范围.
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