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Formation of Supramolecular Clusters at the Interface of Zeolite X Following the Adsorption of Rare-Earth Cations and Their Impact on the Macroscopic Properties of the Zeolite

TitleFormation of Supramolecular Clusters at the Interface of Zeolite X Following the Adsorption of Rare-Earth Cations and Their Impact on the Macroscopic Properties of the Zeolite
Publication TypeArticolo su Rivista peer-reviewed
Year of Publication2018
AuthorsGuzzinati, Roberta, Sarti E., Catani M., Costa V., Pagnoni A., Martucci A., Rodeghero E., Capitani D., Pietrantonio Massimiliana, Cavazzini A., and Pasti L.
JournalChemPhysChem
Volume19
Pagination2208-2217
ISSN14394235
Abstract

The adsorption behavior of neodymium (Nd3+) and yttrium (Y3+) cations on synthetic FAU zeolite X in its sodium form (NaX) has been investigated by means of macroscopic (adsorption isotherm determination and thermal analysis) and microscopic measurements (including solid-state NMR spectroscopy and X-ray powder diffraction). The multidisciplinary study reveals some unexpected features. Firstly, adsorption constants of cations are not correlated to their ionic radii or hydration enthalpy. The adsorption constant of Y3+ on NaX was indeed about twice that of Nd3+, which is the opposite of what could be expected based on the size of the cations. In addition, adsorption was accompanied by partial dealumination of the zeolite framework. The extent of dealumination changed depending on the exchanged cations, with the extent being more significant on the Nd-exchanged zeolite than on the Y-exchanged one. The most interesting finding of this study, however, is the presence of supramolecular clusters composed of water, Nd3+, residual sodium ions, and extra-framework aluminum at the interface of Nd-exchanged zeolite. The hypothesis that these host-guest complexes are responsible of the significantly different behavior exhibited by NaX towards the adsorption/desorption of Nd3+ and Y3+ has been formulated. © 2018 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim

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URLhttps://www.scopus.com/inward/record.uri?eid=2-s2.0-85052750256&doi=10.1002%2fcphc.201800333&partnerID=40&md5=332a6f2462373910c383d81364588660
DOI10.1002/cphc.201800333
Citation KeyGuzzinati20182208