科研之友
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摘要
Transmission electron microscopy (TEM) was used to investigate microstructure and chemistry of Rh-loaded ZrO2-CeO2 catalyst exposed to oxidizing and two types of reducing atmospheres. In the oxidized sample Rh was dispersed on the ceria-zirconia support, while metallic Rh was precipitated in both H-2 and CO reduced samples. The size distribution of Rh particles in the H-2-reduced sample is narrower than in samples reduced in CO. Electron energy-loss spectroscopy (EELS) fine structure indicates that both Ce4+ and Ce3+ coexist in the oxidized sample while the reduced sample appears to be predominantly Ce3+. We discuss the orientation relations of Rh and the ceria-zirconia support and the formation of superstructure in ceria-zirconia support in the reduced samples. We also briefly discuss the thermodynamics of the Rh particle reduction and on ordering in the yttrium/lanthanum-doped ceria-zirconia.
- 出版日期2011-7-28
