High Temperature Oxide Aerogels

Numerous applications from insulation to catalytic supports and fuel cells can benefit from lightweight, high surface area, mesoporous materials which maintain their mesoporous structure to temperatures of 600 to 1200 °C. Polymeric aerogels are limited to temperatures of nominally 400 °C due to thermal degradation of organic groups. Silica aerogels begin to densify by 700 °C. A number of aerogel systems show stability at higher temperatures, including alumina, alumina silicates, yttrium-doped alumina, and zirconia and yttria-stabilized zirconia aerogels. Within a given chemical composition, the morphology and textural stability of a mesoporous structure is dependent upon the synthesis method used. Other important considerations in choosing an aerogel composition include the time at temperature required for a given application, phase transformations inherent in a given system, and approaches to phase stabilization such as introduction of dopants into the backbone structure. Reinforcement of the aerogel through a composite approach also is addressed.