An emulsion method for producing fine, low density, high surface area silica powder from alkoxides
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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).
KeywordsAlkoxide Amorphous Silica High Specific Surface Area Orthosilicate Tetraethyl
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