清液体系中高性能T型沸石分子筛膜的合成

由摩尔组成为SiO2:Al2O3:Na2O:K2O:H2O=1:0.015:0.25:0.08:25的澄清溶液,在预涂晶种的管状莫来石支撑体上水热合成T型沸石分子筛膜.在高于100℃清液体系中合成出了高性能T型沸石分子筛膜.用X射线衍射(X-ray diffraction,XRD)仪和扫描电子显微镜(scanning electron microscope,SEM)对150℃下合成35 h的分子筛膜进行了表征.XRD谱表明:T型沸石分子筛成功地生长在预涂晶种的支撑体上.支撑体的外表面覆盖着20 μm厚有取向的晶体层.从SEM照片判断,起到分离作用的是生长致密的中间层,而不是表层.在150℃下制备的膜,对水/乙醇、水/异丙醇混合物具有高渗透汽化分离性能.优异的渗透汽化性能归因于在涂有晶种的多孔支撑体上生长了一层高结晶度且缺陷较少的T型沸石分子筛晶体层.

SYNTHESIS OF ZEOLITE T MEMBRANES WITH HIGH PERFORMANCE FROM CLEAR SOLUTIONS

Zeolite T membranes were prepared on pre-seeded mullite tubes by hydrothermal synthesis from clear solutions with a molar composition of SiO2:Al2O3:Na2O:K2O:H2O=1:0.015:0.25:0.08:25. The synthesis of high performance zeolite T membrane above 100 ℃ from clear solutions was reported. The membrane synthesized at 150 ℃ for 35 h was characterized by X-ray diffraction (XRD) and scanning electron microscope (SEM). The XRD pattern indicated that the zeolite T crystals were successfully grown onto the pre-seeded mullite tube support. The outer surface of the porous support was covered with oriented zeolite T crystals of about 20 μm in thickness. The intermediate layer packed densely with zeolite T crystals would act as an active layer for separation rather than the top layer, judged from SEM observation. The membrane prepared at 150 C showed high pervaporation properties for water/ethanol and water/isopropanol liquid mixtures. The good pervaporation performance would be attributed to the high crystallinity and the few defects contained in the zeolite T crystal layer grown on the seeded porous tube.