Diffusive hydrogen inter-cage migration in hydrogen and hydrogen-tetrahydrofuran clathrate hydrates

Cao, Hui; English, Niall J.; MacElroy, J. M. D.

doi:10.1063/1.4793468

Cited by 56 publications

(73 citation statements)

References 54 publications

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“…10 Molecular dynamics (MD) simulations have been applied to understand the evolution of a LDA ice to a high-density amorphous ice 11,12 while considering temperature and pressure effects or to study the high-density amorphous ice/crystalline ice I h compressiondecompression at a fixed low temperature. 13 Diffusion of small molecules, in crystalline ice, [14][15][16][17][18] clathrates 18,19 and hydrates, 20 has also been studied with molecular dynamics. The previously established interstitial mechanism for He atoms in ice I h 16 has been found inappropriate for the N 2 molecules.…”

Section: Introductionmentioning

confidence: 99%

“…15 The most recent work on CO 2 diffusion in clathrates has revealed that CO 2 diffusion is possible in these solids if water vacancy exists. 18 Diffusion has also been quantified in structure materials like H 2 , tetrahydrofuran clathrate hydrates 19 or for water in cyclodextrin hydrates. 20 For a more complete insight into molecular diffusion in clathrates we recommend the very recent review by English and MacElroy 21 on molecular simulation of clathrate hydrates.…”

Section: Introductionmentioning

confidence: 99%

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Diffusion of molecules in the bulk of a low density amorphous ice from molecular dynamics simulations

Ghesquière

Mineva

Talbi

et al. 2015

Phys. Chem. Chem. Phys.

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The diffusion of molecules in interstellar ice is a fundamental phenomenon to take into account while studying the formation of complex molecules in this ice. This work presents a theoretical study on the diffusion of H2O, NH3, CO2, CO, and H2CO in the bulk of a low density amorphous (LDA) ice, while taking into account the physical conditions prevailing in space, i.e. temperatures below 150 K and extremely low pressure. This study was undertaken by means of molecular dynamics simulations. For CO2 for which no experimental data were available we conducted our own experiments. From our calculations we show that, at low temperatures, the diffusion of molecules in the bulk of a LDA ice is driven by the self-diffusion of water molecules in the ice. With this study we demonstrate that molecular dynamics allows the calculation of diffusion coefficients for small molecules in LDA ice that are convincingly comparable to experimentally measured diffusion coefficients. We also provide diffusion coefficients for a series of molecules of astrochemical interest.

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Diffusion of molecules in the bulk of a low density amorphous ice from molecular dynamics simulations

Ghesquière

Mineva

Talbi

et al. 2015

Phys. Chem. Chem. Phys.

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“…26 In both experiments, the clathrate crystal structure remained intact, demonstrating that the diffusive migration of H 2 must take place, 26 and the small cages always remained singly occupied by H 2 . [33][34][35][36] In two of these studies, 35,36 the free-energy barriers were computed for different H 2 occupancy of the neighboring large cages, and the barrier heights were found to decrease rather strongly with increasing H 2 occupancy.…”

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confidence: 99%

Competing quantum effects in the free energy profiles and diffusion rates of hydrogen and deuterium molecules through clathrate hydrates

Cendagorta

Powers

Maršálek

et al. 2016

Phys. Chem. Chem. Phys.

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Clathrate hydrates hold considerable promise as safe and economical materials for hydrogen storage. Here we present a quantum mechanical study of H 2 and D 2 diffusion through a hexagonal face shared by two large cages of clathrate hydrates over a wide range of temperatures. Path integral molecular dynamics simulations are used to compute the free-energy profiles for the diffusion of H 2 and D 2 as a function of temperature. Ring polymer molecular dynamics rate theory, incorporating both exact quantum statistics and approximate quantum dynamical effects, is utilized in the calculations of the H 2 and D 2 diffusion rates in a broad temperature interval. We find that the shape of the quantum free-energy profiles and their height relative to the classical free energy barriers at a given temperature, as well as the rate of diffusion, are profoundly affected by competing quantum effects: above 25 K, zero-point energy (ZPE) perpendicular to the reaction path for diffusion between cavities decreases the quantum rate compared to the classical rate, whereas at lower temperatures tunneling outcompetes the ZPE and as result the quantum rate is greater than the classical rate.

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“…270 K) (Pefoute et al, 2012 ). At higher pressure (typically several tens of bars), studies of molecular hydrogen diffusion into THF hydrates have been performed by means of NMR method (Okuchi et al, 2007 ), in situ neutron diffraction (Mulder et al, 2008 ), volumetric measurements (Nagai et al, 2008 ), theoretical calculations (Alavi and Ripmeester, 2007 ) and molecular dynamics simulations (Cao et al, 2013 ). These measurements, performed in various P-T thermodynamics conditions, lead to diffusion coefficient ranging from ca .…”

Section: Introductionmentioning

confidence: 99%

Promoting the Insertion of Molecular Hydrogen in Tetrahydrofuran Hydrate With the Help of Acidic Additives

et al. 2020

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Among hydrogen storage materials, hydrogen hydrates have received a particular attention over the last decades. The pure hydrogen hydrate is generated only at extremely high-pressure (few thousands of bars) and the formation conditions are known to be softened by co-including guest molecules such as tetrahydrofuran (THF). Since this discovery, there have been considerable efforts to optimize the storage capacities in hydrates through the variability of the formation condition, of the cage occupancy, of the chemical composition or of the hydrate structure (ranging from clathrate to semi-clathrate). In addition to this issue, the hydrogen insertion mechanism plays also a crucial role not only at a fundamental level, but also in view of potential applications. This paper aims at studying the molecular hydrogen diffusion in the THF hydrate by in-situ confocal Raman microspectroscopy and imaging, and at investigating the impact of strong acid onto this diffusive process. This study represents the first report to shed light on hydrogen diffusion in acidic THF-H 2 hydrate. Integrating the present result with those from previous experimental investigations, it is shown that the hydrogen insertion in the THF hydrate is optimum for a pressure of ca . 55 bar at 270 K. Moreover, the co-inclusion of perchloric acid (with concentration as low as 1 acidic molecules per 136 water molecules) lead to promote the molecular hydrogen insertion within the hydrate structure. The hydrogen diffusion coefficient—measured at 270 K and 200 bar—is improved by a factor of 2 thanks to the acidic additive.

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Diffusive hydrogen inter-cage migration in hydrogen and hydrogen-tetrahydrofuran clathrate hydrates

Cited by 56 publications

References 54 publications

Diffusion of molecules in the bulk of a low density amorphous ice from molecular dynamics simulations

Diffusion of molecules in the bulk of a low density amorphous ice from molecular dynamics simulations

Competing quantum effects in the free energy profiles and diffusion rates of hydrogen and deuterium molecules through clathrate hydrates

Promoting the Insertion of Molecular Hydrogen in Tetrahydrofuran Hydrate With the Help of Acidic Additives

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