GreenShift Invests in Aerogel Composites for Fuel Cell and Catalytic Applications
22 November 2005
|Transmission Electron Microscope image of aerogel|
GreenShift Corporation, a business development corporation that invests in emerging companies and technologies which might enable large environmental gains, is taking a 25% position ($500,000) position in Aerogel Composite (ACI), a development-stage company making meso-porous carbon aerogel composites.
ACI has patented a process for the preparation of aerogel composites destined for a variety of applications, including carbon aerogel-supported catalysts for fuel cells and other metal oxide aerogel-supported catalysts for catalytic converters for combustion engines.
Aerogels are solid-state substances similar to gels but in which the liquid phase is replaced with gas. Aerogels have a highly dendritic (branching like a tree) structure and rank among the world’s lowest density solids.
They have a remarkably high surface area and are very porous and light. Their microstructure and physical properties can be manipulated at the nanometer scale by selection of raw material and modification of manufacturing conditions. Aerogel materials can be produced as monoliths, thin-films, powders, or micro-spheres to respond to given application requirements.
|The process of aerogel formation using sol-gel polycondensation reaction technology.|
There are three major types of aerogels:
Inorganic aerogels are obtained by supercritical drying of highly cross-linked hydrogels synthesized by polycondensation of metal alkoxides. Silica aerogels are the most well known inorganic aerogels.
Organic aerogels are synthesized by supercritical drying of the gels obtained by the sol-gel polycondensation reaction of resorcinol with formaldehyde in aqueous solutions.
Carbon aerogels are prepared by pyrolyzing organic aerogels in an inert atmosphere. Carbon aerogels are electrically conductive and have very high porosity of over 50%, with pore diameters ranging from 2 to 50 nanometers, and extremely high surface areas ranging between 400-1000 square meters per gram.
Incorporation of additives into aerogels results in materials that are called aerogel composites. The role of the additives is to enhance the properties of pure aerogels or to impart additional desirable properties depending on the application.
The nanostructure of the ACI carbon aerogel offers high electrochemical surface areas, good mass transport, low or eliminated ionic contamination and price competitiveness. This translates into both lower cost and higher performance when applied to current membranes on the market. ACI’s initial products are high performance electro-catalysts for fuel cells, non-electro-catalysts for emissions control, and aerogel materials for energy storage.
ACI’s electro-catalyst products achieve equivalent catalytic performance at one half to one tenth the precious metal loading commonly achieved by current technology. These catalysts are the primary cost drivers in all of the markets ACI is addressing. ACI’s technology directly addresses the cost of fuel cell systems by lowering the platinum cost in the membrane electrode assembly (MEA).
For example, ACI’s Hyrogel Carbon Aerogel Supported Platinum Catalyst (CASPC) reduces the platinum requirements of hydrogen-powered proton exchange membrane (PEM) fuel cells by more than 90% from recently prevailing levels. Based on industry feedback, ACI believes that its electro-catalyst is the most efficient and most economical PEM electro-catalyst available today.
ACI has also produced catalyst coated membrane (CCMs) or three-piece membrane electrode assemblies (MEAs) for PEM fuel cells, incorporating its Hyrogel electro-catalyst. These CCMs/MEAs have achieved a performance of one watt per square centimeter, requiring less than 0.1 milligram per square centimeter of platinum on the cathode. Based on industry data, ACI believes that this performance is unmatched.
Additionally, in catalytic emissions control systems, the aerogel-supported platform reduces precious metal loading and therefore cost. In 2003, the $4 billion market for emission control catalysts utilized $3.19 billion of platinum group metals. This market is expected to grow significantly due to increased regulation, stricter enforcement and rising demand for diesel automobiles in Europe and the U.S.
Other potential applications include materials for ultracapacitor electrodes, hydrogen and energy storage, catalyst for fuel reformers, specific gas sensors, biosensors, and desalination of water.