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Surfaces modèles or-palladium étudiées in situ:
de l'ultra-vide aux conditions de réactions catalytiques

Abstract : Fundamental understanding of catalytic processes implies to correlate the atomic-scale structure of catalysts during a reaction with the macroscopic properties. This thesis work is in this frame and the main tool is the surface x-ray diffraction. An instrumental part is devoted to the development of a reactor which allows to characterise in situ the surfaces of model catalysts during a given reaction (up to 1 bar), by means of x-ray diffusion-based techniques. The main reactor features, as well as the first commissioning tests are described.
A more fundamental part is dedicated to the study of bimetallic model surfaces based on gold and palladium with on one hand, gold deposits on Pd(110) and on the other hand, the (111) and (110) surfaces of the Au30Pd70 bulk alloy.
The study of Au/Pd(110) in ultra-high vacuum has benefited from the complementarity between surface x-ray diffraction and scanning tunneling microscopy. For thicknesses up to 2.5 ML and annealing temperatures up to 470°C, the growth, structure and morphology of gold deposits are described.
Finally, the study led on the Au30Pd70 bulk alloy has confirmed the interest of x-ray diffraction for characterising these model surfaces during a catalytic reaction. The structure of the (110) and (111) faces has been firstly studied in ultra-high vacuum and then during exposures at low pressures of hydrogen and oxygen (up to 10-5 mbar). Consecutively, the selective butadiene hydrogenation has been studied on the (111) surface, in the new reactor with the final aim to characterise the structure at different steps of the reaction. A strong effect of pure hydrogen on the volume and the surface of the alloy has been evidenced. These modifications are discussed in relation to the catalytic properties.
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https://tel.archives-ouvertes.fr/tel-00011720
Contributor : Aude Bailly <>
Submitted on : Friday, March 3, 2006 - 11:20:36 AM
Last modification on : Thursday, January 11, 2018 - 6:21:33 AM
Long-term archiving on: : Tuesday, April 6, 2010 - 4:26:15 PM

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  • HAL Id : tel-00011720, version 1

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Aude Bailly. Surfaces modèles or-palladium étudiées in situ:
de l'ultra-vide aux conditions de réactions catalytiques. Analyse de données, Statistiques et Probabilités [physics.data-an]. Université Joseph-Fourier - Grenoble I, 2005. Français. ⟨tel-00011720⟩

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