Preparation of porous silica gel

Preparation of porous spherical silica gel beads by suspension gelation is described. Silica sol prepared from sodium silicate and dilute hydrochloric acid at pH 4-5 dispersed various organic solvents. Sol droplets gelled to hydrogel which upon drying yields porous silica gel beads. Porosity of silica gel beads was varied by treatment of air dried hydrogel with ammonia and hydrothermal treatment. Silica beads prepared from an aged sol and hexamethylene tetramine had the highest pore volume and surface area. (author)