Synthesis of High Surface Area Silica Gels Using Porous Carbon Matrices

Porous silica was prepared using the sol-gel synthesis with porous carbon matrices as a pore-forming support. Tetraethoxysilane (TEOS) was hydrolyzed in an acid medium in the presence of a substoichiometric amount of water. Various carbon materials were used, among them Sibunit and catalytic filamentous carbon. Carbon matrices were impregnated with hydrolyzed TEOS and dried, then carbon was removed by burning out in air at 873 K. The obtained porous silica samples were studied by adsorption and electron microscopic methods. The specific surface area as high as 1267 m²g and pore volume as high as 5.7 cm³/g were determined for some silica samples. Thus deposited SiO₂ was found to cover the carbon surface copying its surface. With CFC used as carbon matrix, silica nanotubes were obtained. Thermostability of such silica is significantly greater as compared to silica gels reported earlier.