Aerogel Composite Applications

Use as Catalysts : A catalyst is a substance that promotes a chemical reaction without becoming permanently involved in the reaction. Supported precious metal catalysts are used to catalyze a wide variety of reactions. Supports are generally high surface area materials such as alumina, silica and carbon. The activity and selectivity for a particular reaction depend in a complicated manner on a wide variety of factors including the average pore size and pore size distribution, the dispersion of the metal and metal-support interactions. Precious metal aerogel nanocomposites are alternatives to supported precious metal catalysts. Unlike conventional catalysts, their properties can be tailored at the nanometerscale to maximize activity and selectivity for a particular reaction.

Use as Electrocatalyst for Fuel Cells : A polymer electrolyte membrane fuel cell (PEMFC) is an electrochemical device that produces electricity, heat and water by combining hydrogen and oxygen gas. The PEMFC is being developed aggressively for use in on-site power generation and for the replacement of the internal combustion engine in vehicle applications. The PEMFC is comprised of a membrane electrode assembly (MEA) typically made of an ionically conducting polymeric membrane sandwiched between two electronically conducting electrodes. Typical electrodes for PEMFC applications are made of a gas diffusion layer (usually porous carbon paper) supporting a layer of finely dispersed platinum on carbon catalyst.

Use as Sensors : Chemical sensors are miniaturized analytical devices, which can deliver real-time and on-line information on the presence of specific compounds or ions in gas or liquid streams. Sensing is generally an analyte recognition process which is followed by the conversion of chemical information into an electrical or optical signal. Aerogels are very attractive as sensor components due to their high surface areas andporous structures with interconnected pores. The high surface area is crucial to maximize the analyte capture efficiency and thus sensitivity. Nanocomposites of aerogels with metals and/or other chemicals which can act as molecular recognition centers are under development.

Use as Adsorbents : Adsorbents are porous materials that are used to remove toxic organic compounds from liquid or vapor streams. Among aerogels, the high surface area and strong affinity of carbon aerogels for organic compounds make them particularly attractive as high capacity adsorbents. The ability to control the pore size and the narrow pore size distribution enables one to develop aerogel based adsorbents that can selectively remove one of the components in a mixture based on molecular size.

Use as Chromatographic Packings : Liquid or gas chromatography is used to separate a mixture into its components. Such a separation is achieved due to different affinities of components in the mixture for chromatographic packings. Aerogel based chromatographic packings are under development for a wide variety of separations.