Cation redistribution upon dehydration of Na58Y faujasite zeolite: a joint neutron diffraction and molecular simulation study |
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Authors: | Wilfried Louisfrema Florence Porcher Jean-Louis Paillaud Pascale Massiani Anne Boutin |
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Affiliation: | 1. Ecole Normale Supérieure, PSL Research University, CNRS, UMR PASTEUR, Sorbonne Université, UPMC Univ Paris 06, F-75005Paris, France;2. Sorbonne Université, UPMC Univ Paris 06, CNRS, UMR PHENIX, F-75005Paris, France;3. CNRS, CEA, UMR, Laboratoire Léon Brillouin, F-91191Gif-sur-Yvette Cedex, France;4. Univ Lorraine, CNRS, UMR CRM2, F-54506Vand?uvre-lès-Nancy, France;5. Univ Haute-Alsace UHA, CNRS, UMR IS2M, F-68093Mulhouse, France;6. Sorbonne Université, UPMC Univ Paris 06, CNRS, UMR LRS, F-75005Paris, France |
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Abstract: | Using neutron scattering and Monte Carlo simulation, we investigate the distribution of cations in Na58Y faujasite upon (de)hydration. We introduce a new method for the assignment of cations to specific sites in molecular simulations from their local environment. This allows us to bypass the need of the coordinates of crystallographic sites, which vary as water adsorption induces changes in the zeolite framework structure. Although the agreement between experiments and simulation is excellent at high temperature, some differences are observed below 150°C. We show that these differences are due to the presence of water and that temperature itself as well as adsorption-induced deformation of the framework play a less important role. We demonstrate the migration of sodium to sites III upon water adsorption, not observed for other Si:Al ratios. |
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Keywords: | faujasite cation localisation hydration Monte Carlo neutron diffraction |
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