A Numerical Evidence for Nonframework Cation Redistribution Upon Water Adsorption in Faujasite Zeolite

Beauvais, Christèle; Boutin, Anne; Fuchs, Alain H.

doi:10.1002/cphc.200400195

Cited by 41 publications

(60 citation statements)

References 19 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…in so called sites I'). [31] It is worth noticing that the water fills the porous volume homogeneously. For QCMD simulations, initial configurations with different numbers of water molecules were extracted from GCMC.…”

Section: Resultsmentioning

confidence: 99%

Confinement effect on the hydrated electron behaviour

Coudert

Boutin

2006

Chemical Physics Letters

Self Cite

View full text Add to dashboard Cite

We report the first direct simulation of an excess hydrated electron confined in a zeolite nanopore by means of mixed quantum-classical molecular dynamics. The experimental dependence of the hydrated electron absorption spectrum maximum upon water loading in faujasites is reproduced. The diffusion of the confined hydrated electron is also studied and a prediction of the diffusion coefficient is provided.

show abstract

Section: Resultsmentioning

confidence: 99%

Confinement effect on the hydrated electron behaviour

Coudert

Boutin

2006

Chemical Physics Letters

Self Cite

View full text Add to dashboard Cite

show abstract

“…The parameters are taken from Jaramillo et al [12] for the zeolite framework (in particular, Si and Al atoms are described as "T atoms" carrying identical charges) and from Dang et al [13] for Na + cations, together with the TIP4P water model of water [14]. This force field was successfully used in previous studies of water adsorption in Y and X zeolites [4,5,6,15,16]. Periodic boundary conditions are used, electrostatic interactions are computed using Ewald summation and a cut-off equal to half the box length is used to compute Lennard-Jones interactions.…”

Section: Monte Carlo Simulationsmentioning

confidence: 99%

“…One of the reasons for the discrepancy between cation location results is the strong sensitivity of cation distribution to experimental conditions (temperature, dehydration conditions, nature and quantity of sorbed molecules …) [1,3]. The presence of water has been shown to drastically modify the cation location in zeolites and in particular in faujasite zeolite [4,5,6,7,8]. The experimental determination of cation location in hydrated sample is complicated because of partial occupancies affecting low symmetry sites.…”

Section: Introductionmentioning

confidence: 99%

Cation redistribution upon dehydration of Na₅₈Y faujasite zeolite: a joint neutron diffraction and molecular simulation study

Louisfrema

Rotenberg

Porcher

et al. 2015

Molecular Simulation

Self Cite

View full text Add to dashboard Cite

Using neutron scattering and Monte Carlo simulation, we investigate the distribution of cations in Na 58 Y 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. While 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.

show abstract

“…Therefore the use of these powerful methods must be restricted to the study of a limited number of molecular sieves in a limited number of temperature and adsorption conditions. However contrast powder diffraction analyses appear fully complementary with the work undertaken in the field of molecular simulations where significant advances have occurred in the codes and the potentials [39,40].…”

Section: Resultsmentioning

confidence: 99%

Towards Operando Characterisation by Powder Diffraction Techniques of Molecular Sieves

Pichon

Palancher

Hodeau

et al. 2005

Oil & Gas Science and Technology - Rev. IFP

View full text Add to dashboard Cite

Résumé -Vers la caractérisation operando de tamis moléculaires par diffraction par les poudres -Les tamis moléculaires en poudres présentent des atomes nombreux et variés. Leur caractérisation nécessite des sondes sélectives chimiquement. Ils peuvent être caractérisés soit par diffraction des neutrons soit par diffraction anomale des rayons X pour obtenir des informations sur la structure de ces matériaux. Nous allons illustrer la complémentarité de ces méthodes par l'analyse de deux processus chimiques sur des zéolithes X. Dans une première partie, nous présentons l'analyse structurale d'une zéolithe X échangée au baryum par diffraction des neutrons après une étape de préparation ex situ consistant à saturer la zéolithe BaX par un mélange d'eau lourde et de para-xylène deutéré. La sensibilité aux atomes légers de la diffraction des neutrons nous a permis de proposer une localisation précise des molécules d'eau et de xylène composant la phase adsorbée dans la micro-porosité de la zéolithe. La deuxième partie de ce travail est dédiée à la caractérisation structurale pendant le processus de déshydratation de la zéolithe X échangée par les cations strontium et rubidium. Cette caractérisation in situ a été obtenue par l'enregistrement, pour chaque état de la zéolithe (hydratée, déshydratée), de trois diagrammes de diffraction des rayons X, deux à une énergie proche du seuil d'absorption des rayons X de chaque cation de compensation (Sr 2+ et Rb + ) et un loin de ces deux seuils d'absorption. La sélectivité chimique de la diffraction résonante a permis d'obtenir des informations précises sur la distribution des cations de compensation (en termes de localisation et de répartition) et sur leur mobilité en fonction des conditions expérimentales. En conclusion, nous résumons quelques spécificités et limitations des deux méthodes. Abstract-Towards operando Characterisation by Powder Diffraction Techniques of Molecular Sieves-Working molecular sieves imply numerous and various atoms and for their characterisation we need chemical selective probes. Thus they can be studied either by neutron powder diffraction or by anomalous X-ray powder diffraction techniques to extract structural information. We will illustrate the complementarities of these methods in the analysis of two different chemical processes on X-type zeolite.In the first case, a fully exchanged barium X-type zeolite was, firstly, characterised by neutron powder diffraction after an ex situ preparation step. During the preparation step, the sample was saturated with and Technology -Rev. IFP, Vol. 60 (2005) Synchrotron and Neutron Solutions to Oil Industry Problems Utilisation des grands instruments analytiques dans l'industrie pétrolièreD o s s i e r Oil & Gas Science

show abstract

A Numerical Evidence for Nonframework Cation Redistribution Upon Water Adsorption in Faujasite Zeolite

Cited by 41 publications

References 19 publications

Confinement effect on the hydrated electron behaviour

Confinement effect on the hydrated electron behaviour

Cation redistribution upon dehydration of Na₅₈Y faujasite zeolite: a joint neutron diffraction and molecular simulation study

Towards Operando Characterisation by Powder Diffraction Techniques of Molecular Sieves

Contact Info

Product

Resources

About

A Numerical Evidence for Nonframework Cation Redistribution Upon Water Adsorption in Faujasite Zeolite

Cited by 41 publications

References 19 publications

Confinement effect on the hydrated electron behaviour

Confinement effect on the hydrated electron behaviour

Cation redistribution upon dehydration of Na58Y faujasite zeolite: a joint neutron diffraction and molecular simulation study

Towards Operando Characterisation by Powder Diffraction Techniques of Molecular Sieves

Contact Info

Product

Resources

About

Cation redistribution upon dehydration of Na₅₈Y faujasite zeolite: a joint neutron diffraction and molecular simulation study