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DOI: 10.1021/JP990375A
Cu/ZnO And Cu/ZnO/SiO2 Catalysts Studied By Low-energy Ion Scattering
Published 1999 · Chemistry
Low-Energy Ion Scattering (LEIS) was employed to study the surface of unsupported and silica-supported Cu/ZnO catalysts. It was shown that, by applying isotopic enrichment (63Cu and 68Zn), the copper and zinc signals can be separated. LEIS measurements showed a considerable amount of lead on the surface of the 63Cu/68ZnO catalyst. It was concluded that lead originated from the 68ZnO raw material and segregated during catalyst reduction to the surface. In contrast, no impurities were detected on the surface of the 63Cu/68ZnO/SiO2 catalyst. This seemingly contradictory observation was attributed to the higher degree of copper and zinc dispersion in the latter catalyst or interaction of lead with the support. It was shown previously, that catalytic activity of Cu/ZnO/SiO2 catalysts in methanol synthesis and ester hydrogenolysis is proportional with the reduction temperature applied (600−750 K). A depth profile of copper and zinc obtained for the high-temperature reduced silica-supported catalyst revealed tha...