Experiments on ceria (cerium oxide) nanoparticles carried out at the U.S. Department of Energys Brookhaven National Laboratory may lead to catalytic converters that are better at cleaning up auto exhaust, and/or to more-efficient ways of generating hydrogen -- a promising zero-emission fuel for the future. Brookhaven chemist Jose Rodriguez will present results from two studies exploring the composition, structure, and reactivity of these versatile nanoparticles during the 229th National Meeting of the American Chemical Society on Tuesday, March 15, at 8:15 a.m. in room Del Mar A of the Hyatt Regency, San Diego, California.
After using a novel technique to synthesize the ceria nanoparticles, Rodriguez and coworkers Xianqin Wang and Jonathan Hanson used bright beams of x-rays at the National Synchrotron Light Source to study how their composition, structure, and reactivity changed in response to doping with zirconium in one case, and impregnation with gold in another. "In a catalytic converter, ceria acts as a buffer, absorbing or releasing oxygen, depending on the conditions of the engine, to maintain the catalyst in its optimum operating condition for converting harmful emissions such as carbon monoxide and nitrogen oxide to carbon dioxide and nitrogen gas," Rodriguez said. Others have found that adding zirconium improves cerias ability to store and release oxygen.
The synchrotron studies at Brookhaven explain why: Zirconium changes the cerias structure to increase the number of oxygen "vacancies" -- or places for oxygen uptake and release. Furthermore, Rodriguez says, "The ceria nanoparticles we studied have much better performance, higher chemical reactivity, than the bulk form of ceria currently used in catalytic converters." Thus, this research holds promise for more-efficient catalytic converters -- and cleaner air.
Karen McNulty Walsh | EurekAlert!
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