Wet silica gels for aerogel and xerogel thermal insulation and processes for the wet gels

摘要

Preparation of a wet silica gel comprises (a) contacting a stable, aqueous, fluid, silica system having a pH > 7.5 with an ion exchange resin to reduce the pH to 5.0, (b) adding an organic liquid to the silica system, the liquid staying in one phase with the aqueous system and not precipitating the silica, and (c) adding base to the system so that the pH of the system is about 5.0-7.5 and allowing the wet silica gel to form. Also claimed is the silica gel having a dry bulk density of about 0.09-0.14 g/cc.