Silica gels were prepared by the hydrolysis of silicon tetrachloride in pure water or in a tetrahydrofuran/water solution; hydrolysis in an ammonia/water solution yielded precipitated silica. After solvent transfer in acetone followed by supercritical point drying using liquid carbon dioxide, aerogel powders with high surface areas (up to 900 m2/g) and low tapping densities (down to 0.040 g/cm3) were produced. The powders were characterised by transmission electron microscopy, thermogravimetric analysis and infrared spectroscopy. © 1995, All rights reserved.
Heley, J. R., Jackson, D., & James, P. F. (1995). Fine low density silica powders prepared by supercritical drying of gels derived from silicon tetrachloride. Journal of Non-Crystalline Solids, 186, 30–36. https://doi.org/10.1016/0022-3093(95)00030-5