XANES studies of the reduction behavior of (Ce1-yZry)O2 and Rh/(Ce1-yZry)O2

Using X-ray absorption near-edge spectroscopy (XANES) at the Ce LIII edge, we have measured the extent of reduction of Rh-loaded and Rh-free, mixed Ce-Zr oxides under hydrogen as a function of temperature. The high surface area, mixed oxides were synthesized by sol-gel techniques and hypercritical d...

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Bibliographic Details
Published in:Catalysis letters 1998-05, Vol.51 (3-4), p.133-138
Main Authors: OVERBURY, S. H, HUNTLEY, D. R, MULLINS, D. R, GLAVEE, G. N
Format: Article
Language:English
Subjects:
Catalysis
Catalysts: preparations and properties
Cerium oxides
Chemistry
Exact sciences and technology
General and physical chemistry
High temperature
Mixed oxides
Reduction
Sol-gel processes
Subtraction
Temperature
Theory of reactions, general kinetics. Catalysis. Nomenclature, chemical documentation, computer chemistry
X ray absorption
Zirconium oxides
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Summary:Using X-ray absorption near-edge spectroscopy (XANES) at the Ce LIII edge, we have measured the extent of reduction of Rh-loaded and Rh-free, mixed Ce-Zr oxides under hydrogen as a function of temperature. The high surface area, mixed oxides were synthesized by sol-gel techniques and hypercritical drying. Using a simple spectrum subtraction method, the degree of reduction has been measured and compared with previous results for CeO2 and (Ce0.5Zr0.5)O2. Addition of Zr lowers the temperature of reduction and increases the extent of Ce reduction. Rh catalyzes the reduction process at low temperatures but does not substantially affect the extent of reduction achieved at high temperature. A synergism between Rh and Zr is found which leads to very high reducibility in the range of 400–600 K.
ISSN:1011-372X
1572-879X
DOI:10.1023/a:1019086428874