Synthesis of mesoporous MCM-48 molecular sieves of high quality in a fluorine-containing system

Mesoporous MCM-48 molecular sieves were synthesized in a fluorinecontaining system using tetraethylorthosilicate (TEOS) as silica source and cetyltrimethylammonium bromide (CTAB) as template. To investigate the influence of various factors for synthesis on the structure and properties of the MCM-48 molecular sieves obtained, they were characterized by Xray diffraction (XRD), N₂ adsorptiondesorption and transmission electron microscopy (TEM). The results showed that under the optimal conditions, i.e. a CTAB/Si ratio of 0.65 and crystallization at 393 K for 24 h, the assynthesized MCM-48 exhibits high crystallinity with a specific surface area of 1 305 m²/g and an average pore size of 2.416 nm.