Synthesis and Characterization of the Novel NaA@Mesosilica Molecular Sieves with Core-Shell Structure

Abstract

The core-shell NaA@Mesosilica molecular sieves have been synthesized with the microporous NaA zeolites as core and the mesoporous silica as a shell by using cetyltrimethylammonium bromide (CTAB) as template agent and tetraethyl orthosilicate (TEOS) as silica source in an extremely dilute liquid environment. The products are characterized by X-ray diffraction, scanning electronic microscopy, transmission electron microscopy and N₂ absorption-desorption. The results show the microporous NaA zeolites are coated by mesoporous silica and mesoporous silica shell can grow vertically along surface of NaA zeolites. Furthermore, after calcium ion exchange, the surface area is as high as ca. 615 m²/g and the pore volume is as ca. 0.284 m³/g.