A cheaper and more efficient process to produce clean hydrogen from hydrocarbon fuels for use in fuel cells uses gold nanotubes to do the job.
University of Wisconsin Chemical and Biological Engineering Professor James Dumesic and Won Kim developed a new nanotechnology method for producing hydrogen gas for fuel cells.
The process typically involves two steps. First, hydrocarbons, such as gasoline or natural gas, are converted into a gaseous mixture of hydrogen, carbon monoxide (CO) and carbon dioxide (CO2). Next, in a process called the water-gas shift, steam is generated and reacted with the CO to produce CO2.
The water-gas shift is needed to remove the CO because CO’s presence in hydrogen gas will poison a fuel cell’s metal electrode. But the water gas shift is costly due to the large amount of energy needed to vaporize water to steam. This technology now provides a catalytic process to remove CO from hydrogen gas that not only eliminates the need for the water-gas shift, but also captures the energy in CO to generate power.
The Wisconsin invention uses gold nanotube or nanoparticle catalysts to oxidize CO to CO2 within an aqueous solution of polyoxometalate (POM) compounds. As the CO is oxidized, the POM compounds are reduced, resulting in an energy-dense solution of protons and electrons associated with the reduced POM cations. This solution can then be fed directly into proton exchange membrane (PEM) fuel cells to generate power.
- Unlike any previous technique for making hydrogen, this invention simultaneously removes CO from gas streams and captures CO’s energy to generate power
- CO to CO2 conversion takes place at room temperature, resulting in significant energy- and cost-savings
- By eliminating the need for the water-gas shift, this invention also eliminates the need for large quantities of water, making on-site or portable hydrogen production more feasible
- Shows particular promise for energy production using renewable, biomass-derived fuels, (e.g., ethylene glycol derived from corn or glycerol derived from bio-diesel production) because these fuels generate hydrogen and CO in nearly equal amounts during catalytic decomposition
- Solutions of reduced POM compounds provide a stable, energy-dense fuel source that can be stored at room temperature
- POMs are environmentally-benign
- Unlike previous CO oxidation methods that use irreversible oxidizing agents (e.g., oxygen), POM compounds are reversibly oxidized, allowing their direct use as fuel sources
- Could lead to much less expensive fuel cell technology, because reduced POM solutions can be re-oxidized to generate electricity by using simple, carbon anodes, rather than expensive platinum ones.
The technologies is available for licensing form the Wisconsin Alumni Research Foundation
For more information on this technology, see Kim, WB et al. (2004) Powering fuel cells with CO via aqueous polyoxometalates and gold catalysts. Science. 305(5688):1280-1283
Intellectual Property Status