Synthesis of nano-sized mesoporous silicas with metal incorporation

The metal oxide-incorporated or -grafted mesoporous silica nanoparticles and nanotubes have been prepared efficiently via a two-step synthetic process, which includes a pre-hydrolysis of the TEOS and metal alkoxides or salts in acidic solution (pH < 1.0), and fast cocondensation of silica, metal oxides and surfactant in alkaline ammonia solution (pH 8.0-9.0). Because the presence of the cationic surfactant and a proper pH range could make the silica condensation fast enough to match a relatively quick metal-oxide condensation, various metal oxides (e.g. Al-, Ti-, V-, Zr-, Fe-oxides) can be homogeneously incorporated into the silica framework or grafted on the silica surface. The XRD, reflectance UV-vis and FT-IR spectrometry and solid state NMR have been performed to further identify the successful incorporation and grafting of metal oxides. The metal oxides-incorporated mesoporous silica nanotubes or nanoparticles with high surface area, large mesoporosity and textural porosity can be considered as a capable catalyst of high connectivity and accessibility. The Al-incorporated mesoporous silica nanoparticles show higher catalytic activity toward the cumene-cracking reaction than the typical mesoporous aluminosilicate. (C) 2004 Elsevier B.V. All rights reserved.