Preparation and Characterization of Ultrafine Crystal TS―1 Films

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.