Cation Migration and Structural Deformations upon Dehydration of Nickel-Exchanged NaY Zeolite: A Combined Neutron Diffraction and Monte Carlo Study

Louisfrema, Wilfried; Paillaud, Jean-Louis; Porcher, Florence; Perrin, Elsa; Onfroy, Thomas; Massiani, Pascale; Boutin, Anne; Rotenberg, Benjamin

doi:10.1021/acs.jpcc.6b05657

Cited by 12 publications

(15 citation statements)

References 60 publications

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“…Based on our results in this study, we posit that H 2 O solvates Cs + guest cations and acts as a lubricating solvation layer, which decreases the energy barrier for unblocking access to the α-cage via Cs + migration, according to a related trapdoor mechanism. Similar roles of solvation relating to the movement of guest cations in zeolites have been previously described − and, in particular, demonstrated for H 2 O in cation-exchanged RHO zeolites . Under this proposed scenario, a small amount of H 2 O (corresponding to 5% relative humidity) in Cs-RHO facilitates the movement of Cs + cations away from their original D8R sites in the dehydrated Cs-RHO zeolite, which in turn facilitates CO 2 access.…”

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confidence: 74%

Cs-RHO Goes from Worst to Best as Water Enhances Equilibrium CO₂ Adsorption via Phase Change

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et al. 2021

Langmuir

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The strong affinity of water to zeolite adsorbents has made adsorption of CO2 from humid gas mixtures such as flue gas nearly impossible under equilibrated conditions. Here, in this manuscript, we describe a unique cooperative adsorption mechanism between H2O and Cs+ cations on Cs-RHO zeolite, which actually facilitates the equilibrium adsorption of CO2 under humid conditions. Our data demonstrate that, at a relative humidity of 5%, Cs-RHO adsorbs 3-fold higher amounts of CO2 relative to dry conditions, at a temperature of 30 °C and CO2 pressure of 1 bar. A comparative investigation of univalent cation-exchanged RHO zeolites with H+, Li+, Na+, K+, Rb+, and Cs+ shows an increase of equilibrium CO2 adsorption under humid versus dry conditions to be unique to Cs-RHO. In situ powder X-ray diffraction indicates the appearance of a new phase with Im3̅m symmetry after H2O saturation of Cs-RHO. A mixed-cation exchanged NaCs-RHO exhibits similar phase transitions after humid CO2 adsorption; however, we found no evidence of cooperativity between Cs+ and Na+ cations in adsorption, in single-component H2O and CO2 adsorption. We hypothesize based on previous Rietveld refinements of CO2 adsorption in Cs-RHO zeolite that the observed phase change is related to solvation of extra-framework Cs+ cations by H2O. In the case of Cs-RHO, molecular modeling results suggest that hydration of these cations favors their migration from an original D8R position to S8R sites. We posit that this movement enables a trapdoor mechanism by which CO2 can interact with Cs+ at S8R sites to access the α-cage.

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confidence: 74%

Cs-RHO Goes from Worst to Best as Water Enhances Equilibrium CO₂ Adsorption via Phase Change

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et al. 2021

Langmuir

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“…The development of a classical force fields able to accurately describe the flexibility of the framework is of particular relevance to capture the ion-induced deformation of the framework because standard force fields typically consider the latter as rigid. ,,− This implies in addition the knowledge of the structure from prior experiments. As a further test of the transferability of the PIM to zeolites, we consider here the distribution of extra-framework cations in hydrated Na 58 Y faujasite.…”

Section: Resultsmentioning

confidence: 99%

Classical Polarizable Force Field To Study Hydrated Charged Clays and Zeolites

et al. 2018

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Following our previous works on dry clays, we extend the classical Polarizable Ion Model (PIM) to hydrated dioctahedral clays, by considering Na-, Cs-, Ca-and Sr-montmorillonites in the mono-and bihydrated states. The parameters of the force field are determined by optimizing the atomic forces and dipoles on density functional theory calculations. The simulation results are compared with results obtained with CLAYFF force field and validated by comparison with experiment. The X-Ray diffraction patterns calculated from classical molecular dynamics simulations performed with the PIM force field are in very good agreement with experiments. We also demonstrate the transferablity of PIM force field to other aluminosilicates, here a faujasite-type zeolite compensated with Na + , with a significant improvement in cation locations compared to non-polarizable force fields.

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“…Zeolites therefore provide a stringent test on the ability of the PIM force field to correctly fields typically consider the latter as rigid. 21,[89][90][91][92][93][94] This further implies the knowledge of the structure from prior experiments. Specifically, we consider here faujasite (FAU) which is the most widely studied zeolite type.…”

Section: Transferability To Zeolitesmentioning

confidence: 99%

Classical Polarizable Force Field To Study Dry Charged Clays and Zeolites

et al. 2017

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We extend the classical Polarizable Ion Model (PIM) to charged clays. We focus on Na-, Ca-, Sr-and Cs-montmorillonite with two types of structures for the octahedral sheet : trans-and cis-vacant. The full set of parameters of the force field is determined by density functional theory calculations, using maximally localized Wannier functions with a force-and dipole-optimization procedure. Simulation results for our polarizable force field are compared to the state-of-the-art non-polarizable flexible force field named Clay Force Field (ClayFF), in order to assess the importance of taking polarization effects into account for the prediction of structural properties. This force field is validated by comparison with experimental data. We also demonstrate the transferability of this force field to other aluminosilicates by considering faujasite-type zeolites and comparing the cation distribution for anhydrous Na, Ca, and Sr Y (and X) faujasites predicted by the PIM model and with experimental data.

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Cation Migration and Structural Deformations upon Dehydration of Nickel-Exchanged NaY Zeolite: A Combined Neutron Diffraction and Monte Carlo Study

Abstract: International audienc

Cited by 12 publications

References 60 publications

Cs-RHO Goes from Worst to Best as Water Enhances Equilibrium CO₂ Adsorption via Phase Change

Cs-RHO Goes from Worst to Best as Water Enhances Equilibrium CO₂ Adsorption via Phase Change

Classical Polarizable Force Field To Study Hydrated Charged Clays and Zeolites

Classical Polarizable Force Field To Study Dry Charged Clays and Zeolites

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Cation Migration and Structural Deformations upon Dehydration of Nickel-Exchanged NaY Zeolite: A Combined Neutron Diffraction and Monte Carlo Study

Abstract: International audienc

Cited by 12 publications

References 60 publications

Cs-RHO Goes from Worst to Best as Water Enhances Equilibrium CO2 Adsorption via Phase Change

Cs-RHO Goes from Worst to Best as Water Enhances Equilibrium CO2 Adsorption via Phase Change

Classical Polarizable Force Field To Study Hydrated Charged Clays and Zeolites

Classical Polarizable Force Field To Study Dry Charged Clays and Zeolites

Contact Info

Product

Resources

About

Cs-RHO Goes from Worst to Best as Water Enhances Equilibrium CO₂ Adsorption via Phase Change

Cs-RHO Goes from Worst to Best as Water Enhances Equilibrium CO₂ Adsorption via Phase Change