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Caractérisation des propriétés texturales et de transport de supports de catalyseurs : apport de la RMN du 129Xe

Abstract : Alumina-based catalysts have a crucial importance for a wide range of refining processes. The knowledge of the textural properties of catalyst supports is decisive for the optimization of transport properties of reactants and products.Based on the sensitivity of the highly polarizable electron cloud of xenon atom to its environment, 129Xe NMR has proved to be a very useful technique to study the porosity of microporous and mesoporous solids such as zeolites and silicas. The objective of this PhD thesis is to characterize disorganized materials such as γ-aluminas with this technique.The work presented in this manuscript combine the results of different NMR measurements to characterize the texture and transport properties of aluminas:- After identifying the experimental conditions that minimize the effect of strong adsorption sites on the chemical shift of xenon adsorbed, a correlation has been established between the chemical shift and the pore size determined by nitrogen adsorption at 77 K (Chapter 4).- In order to describe the diffusion coefficients of different adsorbates (Xe, n-hexane) were determined by pulsed field gradient NMR (129Xe and 1H) to characterize diffusion phenomena and to assess pore tortuosities (Chapter 5).- For completing the description of γ-aluminas porosity, pore connectivities, exchange of Xe atoms between different environments has been quantified using 2D-Exchange NMR experiments performed at different temperatures (Chapter 6).
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Erika Weiland. Caractérisation des propriétés texturales et de transport de supports de catalyseurs : apport de la RMN du 129Xe. Chimie-Physique [physics.chem-ph]. Université Pierre et Marie Curie - Paris VI, 2015. Français. ⟨NNT : 2015PA066642⟩. ⟨tel-01490408⟩

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