Emulsion method for producing fine, low density, high surface area silica powder from alkoxides

Article abstract of DOI:10.1007/BF00372177

Fine silica powders were prepared by the hydrolysis and condensation of an emulsion of tetraethyl orthosilicate (TEOS) droplets in a continuous water phase. No additions of alcohol, as a mutual solvent for the TEOS and water, or of strong acid or base catalysts, as required in the more conventional sol-gel methods, were used. The emulsion was produced by mechanical mixing and was stabilized against separating out of the phases by increasing the viscosity of the water with a commercial thickening agent, Texipol. The TEOS/water emulsion reacted to form into a loose particulate gel, which could be crushed to a powder after drying at 40°C. The amorphous silica powders produced had low tapping densities (approximately 0.2 g cm^-3), small particle sizes (< 30 nm) and high specific surface areas (50-400 m²g^-1).