An extended x-ray absorption fine structure study of rhodium-oxygen bonds in a highly dispersed rhodium/aluminum oxide catalyst
| Autor: | J.B.A.D. van Zon, H.F.J. van 't Blik, Azzam N. Mansour, Dale E. Sayers, G.J. Visser, D. R. Short, J. R. Katzer, R Roel Prins, DC Diek Koningsberger |
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| Rok vydání: | 1985 |
| Předmět: |
Extended X-ray absorption fine structure
Coordination number Inorganic chemistry General Engineering chemistry.chemical_element Oxygen law.invention Rhodium Catalysis Metal chemistry law visual_art visual_art.visual_art_medium Physical chemistry Calcination Crystallite Physical and Theoretical Chemistry |
| Zdroj: | The Journal of Physical Chemistry. 89:4075-4081 |
| ISSN: | 1541-5740 0022-3654 |
| DOI: | 10.1021/j100265a030 |
| Popis: | Analysis of in situ EXAFS measurements on a 2.4 wt % Rh/A120, catalyst, reduced at 473 K after calcination at 623 K, shows the presence of two different rhodium-oxygen bonds (viz. 2.05 and 2.68 A). The oxygen neighbors of rhodium at a distance of 2.05 A disappear after reduction at 673 K. The coordination distance 2.05 A is the same as found for Rh203 and indicates that this rhodium-oxygen bond is present due to incomplete reduction of the catalyst at 473 K. Rhodium-oxygen bonds with a coordination distance of 2.68 A are present at both reduction temperatures. These bonds arise from a coordination of the interfacial rhodium atoms with the oxygen ions of the support. Assuming a half-spherical shape for the rhodium metal crystallites, numerical values for the average interfacial rhodium-oxygen coordination number (N = 2.5) and the crystallite diameter (d = 11 A) are derived from the experimental EXAFS parameters. |
| Databáze: | OpenAIRE |
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