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New Catalysts May Create Cheaper Hydrogen In Larger Amounts
Argonne IL (SPX) Sep 21, 2007 A new class of catalysts created at the U.S. Department of Energy's Argonne National Laboratory may help scientists and engineers overcome some of the hurdles that have inhibited the production of hydrogen for use in fuel cells. Argonne chemist Michael Krumpelt and his colleagues in Argonne's Chemical Engineering Division used "single-site" catalysts based on ceria or lanthanum chromite doped with either platinum or ruthenium to boost hydrogen production at lower temperatures during reforming. "We've made significant progress in bringing the rate of reaction to where applications require it to be," Krumpelt said. Most hydrogen produced industrially is created through steam reforming. In this process, a nickel-based catalyst is used to react natural gas with steam to produce pure hydrogen and carbon dioxide. These nickel catalysts typically consist of metal grains tens of thousands of atoms in diameter that speckle the surface of metal oxide substrates. Conversely, the new catalysts that Krumpelt developed consist of single atomic sites imbedded in an oxide matrix. The difference is akin to that between a yard strewn with several large snowballs and one covered by a dusting of flakes. Because some reforming processes tend to clog much of the larger catalysts with carbon or sulfur byproducts, smaller catalysts process the fuel much more efficiently and can produce more hydrogen at lower temperatures. Krumpelt's initial experiments with single-site catalysts used platinum in gadolinium-doped ceria that, though it started to reform hydrocarbons at temperatures as low as 450 degrees Celsius, became unstable at higher temperatures. As he searched for more robust materials that would support the oxidation-reduction reaction cycle at the heart of hydrocarbon reforming, Krumpelt found that if he used ruthenium - which costs only one percent as much as platinum - in a perovskite matrix, then he could initiate reforming at 450 degrees Celsius and still have good thermal stability. The use of the LaCrRuO3 perovskite offers an additional advantage over traditional catalysts. While sulfur species in the fuel degraded the traditional nickel, and to a lesser extent even the single-site platinum catalysts, the crystalline structure of the perovskite lattice acts as a stable shell that protects the ruthenium catalyst from deactivation by sulfur. Krumpelt will present an invited keynote talk describing these results during the 234th national meeting of the American Chemical Society in Boston from August 18 to 23. Seventeen other Argonne researchers will also present their research. Related Links Argonne National Laboratories All about the robots on Earth and beyond!
Engineers Perfecting Hydrogen-Generating Technology
West Lafayette IN (SPX) Aug 29, 2007Researchers at Purdue University have further developed a technology that could represent a pollution-free energy source for a range of potential applications, from golf carts to submarines and cars to emergency portable generators. The technology produces hydrogen by adding water to an alloy of aluminum and gallium. When water is added to the alloy, the aluminum splits water by attracting oxygen, liberating hydrogen in the process. The Purdue researchers are developing a method to create particles of the alloy that could be placed in a tank to react with water and produce hydrogen on demand. |
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