Evidence of Hydronium Formation in Water–Chabazite Zeolite Using Inelastic Neutron Scattering Experiments and ab Initio Molecular Dynamics Simulations
| Autor: | German Sastre, Susana Valencia, Tetiana Lemishko, Mónica Jiménez-Ruiz, Fernando Rey, D. S. Gahle |
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| Přispěvatelé: | Ministerio de Economía y Competitividad (España), Ministerio de Ciencia, Innovación y Universidades (España) |
| Rok vydání: | 2020 |
| Předmět: |
Chabazite
Materials science Hydronium Hydrogen bond 02 engineering and technology Nuclear magnetic resonance spectroscopy 010402 general chemistry 021001 nanoscience & nanotechnology 01 natural sciences Inelastic neutron scattering 0104 chemical sciences Surfaces Coatings and Films Electronic Optical and Magnetic Materials Ab initio molecular dynamics Condensed Matter::Materials Science chemistry.chemical_compound General Energy chemistry Chemical physics Physical and Theoretical Chemistry 0210 nano-technology Zeolite |
| Zdroj: | Digital.CSIC. Repositorio Institucional del CSIC instname RiuNet. Repositorio Institucional de la Universitat Politécnica de Valéncia |
| ISSN: | 1932-7455 1932-7447 |
| Popis: | [EN] A combined study of inelastic neutron scattering and ab initio molecular dynamics simulations has been performed in order to study the water-acid site interaction in zeolite chabazite with a ratio Si/Al = 16 that corresponds to 2 protons/uc with two different water coverages with the number of water molecules being lower and higher than that of proton sites. These results have provided a clear picture of the water-acid site interaction, and it has been demonstrated that there are two regimens of water adsorption, which depend on the water loading. (i) At low water coverage (water/acid site similar to 0.5), the main interactions between water and the zeolitic acid sites are established through hydrogen bond and there is no proton transference to water. (ii) At relatively high water loading (water/acid site similar to 3), the clustering of water molecules and hydronioum cations formed by the complete transference of the zeolitic proton to the water molecules has been observed. The formation of water-hydronium clusters interacting with oxygen atoms of the zeolite framework provides the stabilization energy needed for the protonation of water molecules confined in the cavities of chabazite. These results are the experimental evidence obtained from INS of proton transfer from the zeolitic acid site and the hydronium formation and are in agreement with a previous computational study (Phys. Chem. Chem. Phys. 2009, 11, 1702-1712) and very recent solid state NMR spectroscopy studies (J. Am. Chem. Soc. 2019, 141, 3444-3455). The inspection of the low energy bands (translational and optic modes) and librational bands of the experimental results allows obtaining information about the Hbond network of the hydronium-water cluster We thank MICINN of Spain for funding through Projects RTI2018-101784-B-I00 and SEV-2016-0683. The authors thank the ILL for neutron beam-time allocation (experiment 7-05-456) and the ILL C-Lab for support. A. Moraleda is acknowledged for the synthesis of CHA-16. G.S. and T.L. thank the ILL for the provision of Contract SRH/GRI/AS-15/222 and a Ph.D. contract. |
| Databáze: | OpenAIRE |
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