以椭球形小晶粒TS-1分子筛为晶种, 采用超声法在多孔α-Al2O3载体上获得紧密、均匀、连续的晶种层, 经二次生长形成小晶粒的TS-1分子筛膜. 通过改变合成液碱度(OH-/Si)和晶化时间等合成参数, 调变分子筛膜的微结构. SEM和XRD检测结果表明, 当OH-/Si＝0.09, 水热合成24h时, 晶种没有交联成膜, 延长晶化时间至48h, 可得到致密交联的TS-1分子筛膜, 晶体的大小约为500nm, 进一步延长晶化时间至72h时, 膜的结晶度降低, 表面覆盖一层无定形物质. 提高碱度, OH-/Si＝0.21, 水热反应24h, 得到的膜结构不对称, 上层是高度交联的致密分子筛膜, 晶粒大小约为400nm, 致密膜与载体之间没有交联生长的晶种.
The compact, uniform and continuousseed layers were prepared on porous α-Al2O3 substrateswith oval-shaped and ultrafine seed crystals by ultrasonic seeding, and then TS-1films were formed after secondary growth. The microstructure of the films couldbe regulated by changing the ratios of OH-/Si and the crystallizationtime. SEM and XRD results reveal that when the ratio of OH-/Si is equal to0.09, after 24h of crystallization time, the film is not interconnected. If thecrystallization time is prolonged to 48h, the film have become dense and interconnected,the crystals in which are about 500nm, and when the reaction time is prolongedto 72h, the crystallinity of the film decreases, and the surface of the film iscovered with a layer of amorphous materials. When the ratio of OH-/Si is increasedto 0.21, after 24h of crystallization time, the crystal grains in the top layerare about 400nm and the structure of the TS-1 film is asymmetric, with a denseand uniform TS-1 layer on top, the support at the bottom, and the seed layer inbetween.
参考文献
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