A XANES-TPR study of platinum-rhenium/alumina catalysts
| Autor: | Gary L. Haller, Frank Hilbrig, Chris Michel |
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| Rok vydání: | 1992 |
| Předmět: | |
| Zdroj: | The Journal of Physical Chemistry. 96:9893-9899 |
| ISSN: | 1541-5740 0022-3654 |
| DOI: | 10.1021/j100203a058 |
| Popis: | The authors describe the measurement of X-ray absorption edges to determine the binding energy (chemical shift relative to metallic Pt and Re) to follow the temperature-programmed reduction (TPR) of PtRe/Al{sub 2}O{sub 3} catalysts. Comparison of the derivative of the change in chemical shift with H{sub 2} uptake (both as a function of temperature of reduction) on the reference monometallic catalysts, Pt/Al{sub 2}O{sub 3} and Re/Al{sub 2}O{sub 3}, demonstrate that the two methods of following the reduction are quite similar. X-ray absorption chemical shifts allow the individual TPR of each metal component to be followed independently. When the method was applied to a commercial 0.3 wt % Pt-0.3 wt % Re/Al{sub 2}O{sub 3} catalyst calcined at 180, 250, 400, and 580 {degree}C, the lowest calcination temperature resulted in the coreduction of both Pt and Re. At progressively higher calcination temperatures, the reduction temperature of Re was increased, and after a 580 {degree}C calcination, a part of the Re is coreduced with the Pt and a part is reduced at a substantially higher temperature, probably producing a separate Re phase. While the chemical shift of Pt in Pt/Al{sub 2}O{sub 3} is indistinguishable from bulk Pt, all bimetallic catalysts have a positive chemicalmore » shift, even though the reduction of Pt is likely to be complete. 33 refs., 13 figs.« less |
| Databáze: | OpenAIRE |
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