Highly stable mesoporous silica support having bimodal pore structure

摘要

Thermally and hydrothermally stable mesoporous silica support was successfully prepared with tetrafluoroborate ion under acidic conditions. Serious shrinkage and collapse of pore structure hardly occurred to the stabilized support during thermal treatment at 1173 K and hydrothermal treatment at 373 K due to its thick and hydrophobic pore walls of silica. Furthermore, the support had another attractive characteristic, which was bimodal pore structure. The bimodal support had not only uniform and ordered mesopores (2-3 nm in diameter) but also larger and disordered secondary mesopores (3-15 nm in diameter). Such structure was estimated to be constructed by a couple of properties of BF_4~-. One is the activity on the sol-gel reaction, which was discovered by our group. The other is the strong interaction with surfactants in aqueous solution, which is realized from the Hofmeister effect. It was proposed that formation of silica frameworks was efficiently promoted on the surface of template micelles by the combination of these properties.