Drying of silica aerogel with supercritical carbon dioxide

For applications of monolithic silica aerogels, drying without cracking is an important issue. By extracting alcohol with supercritical CO2, crack-free aerogels can be obtained at 35°C and 85 bar. This opens the possibility for a large-scale aerogel drying process. Besides some technical information about the process, the economics of this process are also discussed. It appears that an aerogel plate with a thickness of 1 cm can be dried at a cost of $2/m2. The price will increase exponentially with thickness because diffusion of the alcohol in the alcogel solvated by CO2 molecules is the rate-determining step of the drying process.