A New Class of Oxidation Catalysts: the role of atomically dispersed metals in nanostructured oxides
نویسندگان
چکیده
The need for high purity hydrogen for use in lowtemperature fuel cells has led to a resurgence of interest in the purification of hydrogen derived from reforming carbon -based feedstocks. A common process used to reduce the carbon monoxide concentration of the reformate gas to an acceptable level is the water gas shift reaction (WGSR). In the reaction, carbon monoxide is combined with water to form carbon dioxide and hydrogen over an appropriate catalyst. Many studies over the last ten years have shown that gold nanoparticles supported on various oxides are effective catalysts for the WGSR. In order to design and optimize such a catalyst it is important to know the details of the catalytic steps involved in the reaction. A number of proposals have been offered to explain the process but all depend on the properties of the metallic gold nanoparticles. Recent work in this laboratory has demonstrated that for the system of nanoparticles of gold on nanocrystalline cerium oxide, the gold nanoparticles do not participate directly in the WGS reaction, but are merely spectators (2). The active catalytic entity is nonmetallic: either a cluster of a few atoms or more likely gold ions. These entities are formed on nanocrystalline cerium oxide, during the initial preparation but once the particles are removed there is no effect on the process. The removal of 90% of the gold that was initially present in the form of metallic particles suggests that the economics of the catalytic process can be improved substantially. This finding formed the basis for the work carried out under this NIRT grant.
منابع مشابه
NANO HIGHLIGHT A New Class of Oxidation Catalysts: The Role of Atomically Dispersed Metals in Nanostructured Oxides
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