Structural aspects of SBA-1 cubic mesoporous silica synthesized via a sol-gel process using a silatrane precursor

Silatrane prepared from fumed silica and triethanolamine was used as a precursor for SBA-1 synthesis at room temperature using cationic surfactants, derived from alkyltrimethylammonium bromides, C_nTMAB (n=14, 16, and 18), as templates in dilute solutions. The influence of acidity, alkyl chain length of the surfactant, and synthesis temperature was studied. The shape of the SBA-1 crystals was dependent on the alkyl chain length of the surfactant. At a high surfactant concentration and an elevated reaction temperature (50°C), three-dimensionally ordered mesopores were invariably produced. Both X-ray diffraction and transmission electron microscopic results showed characteristics of the three-dimensional cubic structure. Scanning electron microscopic images of SBA-1 indicated the crystalline-like appearance of an octadecahedron (18-hedron) consistent with six square [100] and 12 hexagonal [110] planes with a cubic symmetry. The surface area of the product was as high as 1000-1500 m²/g with an adsorption volume of 0.6-1.0 cm ³/g.