渗透汽化异丙醇脱水ZSM-5沸石膜的制备与表征

Preparation and characterization of ZSM-5 zeolite membrane for dehydration of isopropanol via pervaporation

采用二次生长法在无有机模板剂条件下水热晶化制备高质量纯相ZSM-5沸石膜。考察了Na2O/SiO_2摩尔比和Na F/SiO_2摩尔比对制备ZSM-5沸石膜及其结构、形貌与渗透汽化异丙醇脱水分离性能的影响。结果表明,在较低Na2O/SiO_2摩尔比或Na F/SiO_2摩尔比下制备的沸石膜膜层结晶度低;而在较高Na2O/SiO_2摩尔比或Na F/SiO_2摩尔比时,易转晶生成mordenite沸石晶体;仅在Na2O/SiO_2摩尔比为0.17、Na F/SiO_2摩尔比为0.9时,制备出高质量纯相ZSM-5沸石膜,其膜层平整、连续、致密且结晶度高,该膜在渗透汽化异丙醇脱水中具有最佳的分离性能,其渗透通量为3.88 kg/(m2·h),水对异丙醇的分离系数达10 000以上。

High-quality pure phase ZSM-5 zeolite membranes are prepared through hydrothermal crystallization and secondary growth methods under situation of organo-template-free. The influences of the molar ratios of Na2 O/SiO2 and Na F/SiO2 on the preparation,structure,morphology and pervaporation performances of ZSM-5 zeolite membranes are investigated.The results show that ZSM-5 zeolite membranes prepared at lower molar ratio of Na2 O/SiO2 or Na F/SiO2 has a lower crystallinity in membrane layer,and mordenite crystals are easy to form at higher molar ratio of Na2 O/SiO2 or Na F/SiO2.Only when the molar ratios of Na2 O/SiO2 and Na F/SiO2 are 0. 17 and 0. 9,respectively,high-quality pure phase ZSM-5 zeolite membrane can be synthesized,with smooth,continuous,dense and high crystallinity. Such a ZSM-5 zeolite membrane shows high pervaporation performance in dehydration of isopropanol,with a flux of 3. 88 kg·m-2·h-1 and a separation factor of higher than 10 000 for dehydration of isopropanol.