Framework dynamics including computer simulations of the water adsorption isotherm of zeolite Na-MAP

Hill, Jörg‐Rüdiger; Minihan, Alan R.; Wimmer, E.; Adams, Chris J.

doi:10.1039/b003771k

Cited by 32 publications

(28 citation statements)

References 73 publications

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“…For the simulation on the different frameworks, parameters from the augmented consistent valence forcefield aug-CVFF (Hill et al 2000) have been adapted and used as listed in Table 2.…”

Section: Simulationmentioning

confidence: 99%

Characterisation and improvement of sorption materials with molecular modeling for the use in heat transformation applications

2011

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In this paper, several materials for sorption heat transformation applications are evaluated on basis of experimental characterisation and molecular simulation methods. With regard to the application, classical zeolites, ion exchanged zeolites, aluminophosphates as well as silica-aluminophosphates have been analysed. Furthermore samples of metal organic frameworks (MOF) have been evaluated for the use in sorption heat transformation applications with very promising results. In order to understand the fundamental relationship between adsorbent microstructure and water adsorption equilibrium, molecular simulation of water adsorption in various adsorbents are employed. As a result of these simulations within the grand canonical ensemble, the number of water molecules adsorbed in thermodynamic equilibrium under given conditions of temperature and chemical potential (resp. pressure) are obtained. These data are compared with adsorption data from thermogravimetric measurements

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“…For the simulation on the different frameworks, parameters from the augmented consistent valence forcefield aug-CVFF (Hill et al 2000) have been adapted and used as listed in Table 2.…”

Section: Simulationmentioning

confidence: 99%

Characterisation and improvement of sorption materials with molecular modeling for the use in heat transformation applications

2011

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“…Therefore it was necessary to implement a new force field into Cerius 2 that could be used with these water models for the simulation of adsorption in zeolites and OFF as engine. Upon making inquiries in literature (Channon et al, 1998;Hill and Sauer, 1994a, 1995, 1994bHill et al, 2000aHill et al, , 2000 and with help from Accelrys support staff, the augmented Consistent Valence Force Field (CVFF-aug) was selected as the most suitable candidate. We therefore extracted and converted parameter from a BIOSYM-version of the CVFF-aug force field which includes additional atom types and parameters for silicates, aluminsilicates, clays and aluminophosphates.…”

Section: Force Field Implementationmentioning

confidence: 99%

Monte Carlo Investigations of the Water Adsorption Behavior in MFI Type Zeolites for different Si/Al Ratios with Regard to Heat Storage Applications

et al. 2005

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Adsorption processes are turning more and more important for heat transformation applications like thermally driven heat pumps and cooling cycles as well as heat storage. Standard adsorption materials have not been developed for these purposes. New materials are necessary in order to improve the adsorption characteristics for these applications. Molecular simulations are seen as a promising tool to investigate the influence of molecular structure on the adsorption characteristics and thus to provide means for future improvements of such materials for application in heat transformation.Here, Molecular simulations of adsorption isotherms are performed using the Sorption module within Cerius 2 from Accelrys Inc. Existing Force-Fields are examined for their use in Grand Canonical Monte Carlo Simulation (GCMC) of water adsorption in zeolites. The augmented Consistent Valence Force-Field (CVFF-aug) is currently the best available force-field for use with non-polerizable water models like SPC in zeolite frameworks as reported by Hill and Sauer (1994a). Hence, this force field is used to compare simulated adsorption isotherms with experimental data obtained at Fraunhofer ISE for different types of zeolites.The significance of the Al/Si ratio is investigated with regard to a material optimization for the use in heat transformation applications.Furthermore the role of the extra-framework cations is evaluated as different ions are placed inside the zeolite structure. In the first instance the SPC (Berendsen et al., 1981) water model is used in the simulation.

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“…Furthermore, modeling of hydrated systems is notoriously difficult, often failing to accurately reproduce experimental observations. [9] However, we believe that we have made significant progress in this field recently, demonstrating that we are both able to reproduce experimental structures and also to provide thermochemical mechanisms for cation and framework compositions. [10,11] The simulations are based on the classical Born model of solids with interatomic potentials describing the forces between the atoms.…”

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confidence: 97%

Pressure‐Induced Hydration Effects in the Zeolite Laumontite

White¹,

Ruiz‐Salvador²,

Lewis³

2004

Angew Chem Int Ed

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The hydration level of minerals is an important indicator of the conditions prevailing during their formation and during any subsequent geological transformation. The precise water content of mineral zeolites, often highly sensitive to pressure and temperature due to their microporous structure, is particularly key in estimating rock porosity. The presence of the mineral zeolite laumontite near petroleum deposits, for example, can significantly reduce rock permeability, which may limit the production potential of the reservoir.[1] However, since laumontite readily partially dehydrates at ambient conditions [1,2] the exact composition during formation and subsequent diagenesis remains a key question. Neuhoff and Bird [1] [3] and only becomes fully hydrated at elevated pressures. Lee et al. [4][5][6] recently showed that another natural zeolite, natrolite, undergoes pressure-induced overhydration. As a consequence, it is imperative that we can determine the structure of such zeolites at nonambient conditions if we are to understand, not only their geochemistry, but also to assess the impact of extreme conditions on their suitability as, for example, nuclear-waste-containment and barrier materials. Here, we show using computational methods that laumontite can transform from the low-water "leonhardite" composition to the fully hydrated structure under the influence of pressure.Laumontite (LAU·18 H 2 O; Figure 1) is one of the more common natural zeolites. The structure comprises channels bounded by eight tetrahedral units, parallel to the c axis, that contain Ca 2+ ions coordinated to the framework and water (labeled [2] W2 and W8), together with an additional hydrogen-bonded water network (W1 and W5

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Framework dynamics including computer simulations of the water adsorption isotherm of zeolite Na-MAP

Cited by 32 publications

References 73 publications

Characterisation and improvement of sorption materials with molecular modeling for the use in heat transformation applications

Characterisation and improvement of sorption materials with molecular modeling for the use in heat transformation applications

Monte Carlo Investigations of the Water Adsorption Behavior in MFI Type Zeolites for different Si/Al Ratios with Regard to Heat Storage Applications

Pressure‐Induced Hydration Effects in the Zeolite Laumontite

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