Ab Initio Study of Hydrogen Hydrate Clathrates for Hydrogen Storage within the ITBL Environment

Sluiter, M.; Belosludov, Rodion V.; Jain, Amit; Belosludov, V. R.; Adachi, H.; Higuchi, Kenji; Otani, Takayuki

doi:10.1007/978-3-540-39707-6_27

Cited by 15 publications

(14 citation statements)

References 5 publications

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“…6 Following this, Lee et al 13 reported that double occupancy was obtained in the stoichiometric THF-H 2 hydrate using Raman band areas at 12 MPa; these workers indicated that gas evolution measurements confirmed this result. In addition to these experimental results, numerous modeling studies for the pure H 2 [14][15][16][17] and the binary H 2 -THF hydrate 18 have been reported, with much disagreement over the occupancy of H 2 in the 5 12 cavity. The existence or nonexistence of H 2 double occupancy in the small cavities will be a key factor in determining the feasibility of binary cubic clathrate hydrates for hydrogen storage, because double occupancy changes the possible hydrogen concentration in the hydrate from about 1 to 2 wt % for the stoichiometric hydrate.…”

Section: Introductionmentioning

confidence: 98%

Molecular Hydrogen Occupancy in Binary THF−H₂ Clathrate Hydrates by High Resolution Neutron Diffraction

Hester¹,

Strobel²,

Sloan³

et al. 2006

J. Phys. Chem. B

116

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We have determined the time-space average filling of hydrogen molecules in a binary tetrahydrofuran (THF)-d(8) + D(2) sII clathrate hydrate using high resolution neutron diffraction. The filling of hydrogen in the lattice of a THF-d(8) clathrate hydrate occurred upon pressurization. The hydrogen molecules were localized in the small dodecahedral cavities at 20 K, with nuclear density from the hydrogen approximately spherically distributed and centered in the small cavity. With a formation pressure of 70 MPa, molecular hydrogen was found to only singly occupy the sII small cavity. This result helps explain discrepancies about the hydrogen occupancy in the THF binary hydrate system.

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Section: Introductionmentioning

confidence: 98%

Molecular Hydrogen Occupancy in Binary THF−H₂ Clathrate Hydrates by High Resolution Neutron Diffraction

Hester¹,

Strobel²,

Sloan³

et al. 2006

J. Phys. Chem. B

116

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show abstract

“…For the pure hydrogen hydrate, numerous theoretical studies, with various levels of complexity, were performed with inconsistent conclusions regarding the hydrogen occupancy in the small cavity. − Neutron diffraction studies by Lokshin et al . confirmed quadruple occupancy of hydrogen in the large cavities (double and triple occupancies were also found depending on T and P).…”

Section: Introductionmentioning

confidence: 99%

Molecular Hydrogen Storage in Binary THF−H₂ Clathrate Hydrates

et al. 2006

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The hydrogen storage capacity of binary THF-H(2) clathrate hydrate has been determined as a function of formation pressure, THF composition, and time. The amount of hydrogen stored in the stoichiometric hydrate increases with pressure and exhibits asymptotic (Langmuir) behavior to approximately 1.0 wt % H(2). This hydrogen concentration corresponds to one hydrogen molecule occupying each of the small 5(12) cavities and one THF molecule in each large 5(12)6(4) cavity in the hydrate framework. Contrary to previous reports, hydrogen storage was not increased upon decreasing the THF concentration below the stoichiometric 5.6 mol % solution to 0.5 mol %, at constant pressure, even after one week. This provides strong evidence that THF preferentially occupies the large 5(12)6(4) cavity over hydrogen, for the range of experimental conditions tested. The maximum amount of hydrogen stored in this binary hydrate was about 1.0 wt % at moderate pressure (<60 MPa) and is independent of the initial THF concentration over the range of conditions tested.

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“…Single D 2 occupancy of the small cage was established by neutron diffraction also for the binary sII clathrate hydrate with tetrahydrofuran (THF) as the second guest. 7 Several theoretical treatments of the pure H 2 [10][11][12] and the binary H 2 -THF hydrate 13 have been reported. Their main focus was on the thermodynamic stability of the clathrates with different H 2 occupancies, employing a variety of approaches: ab initio electronic structure calculations, alone 10 or combined with a statistical mechanical model, 11 classical molecular-dynamics simulations, 12,13 and lattice dynamics calculations 14 using empirical force fields.…”

Section: Introductionmentioning

confidence: 99%

Hydrogen Molecule in the Small Dodecahedral Cage of a Clathrate Hydrate: Quantum Five-Dimensional Calculations of the Coupled Translation−Rotation Eigenstates

et al. 2006

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We report quantum five-dimensional (5D) calculations of the energy levels and wave functions of the hydrogen molecule, para-H2 and ortho-H2, confined inside the small dodecahedral (H2O)20 cage of the sII clathrate hydrate. All three translational and the two rotational degrees of freedom of H2 are included explicitly, as fully coupled, while the cage is treated as rigid. The 5D potential energy surface (PES) of the H2-cage system is pairwise additive, based on the high-quality ab initio 5D (rigid monomer) PES for the H2-H2O complex. The bound state calculations involve no dynamical approximations and provide an accurate picture of the quantum 5D translation-rotation dynamics of H2 inside the cage. The energy levels are assigned with translational (Cartesian) and rotational quantum numbers, based on calculated root-mean-square displacements and probability density plots. The translational modes exhibit negative anharmonicity. It is found that j is a good rotational quantum number, while the threefold degeneracy of the j = 1 level is lifted completely. There is considerable translation-rotation coupling, particularly for excited translational states.

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Ab Initio Study of Hydrogen Hydrate Clathrates for Hydrogen Storage within the ITBL Environment

Cited by 15 publications

References 5 publications

Molecular Hydrogen Occupancy in Binary THF−H₂ Clathrate Hydrates by High Resolution Neutron Diffraction

Molecular Hydrogen Occupancy in Binary THF−H₂ Clathrate Hydrates by High Resolution Neutron Diffraction

Molecular Hydrogen Storage in Binary THF−H₂ Clathrate Hydrates

Hydrogen Molecule in the Small Dodecahedral Cage of a Clathrate Hydrate: Quantum Five-Dimensional Calculations of the Coupled Translation−Rotation Eigenstates

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Ab Initio Study of Hydrogen Hydrate Clathrates for Hydrogen Storage within the ITBL Environment

Cited by 15 publications

References 5 publications

Molecular Hydrogen Occupancy in Binary THF−H2 Clathrate Hydrates by High Resolution Neutron Diffraction

Molecular Hydrogen Occupancy in Binary THF−H2 Clathrate Hydrates by High Resolution Neutron Diffraction

Molecular Hydrogen Storage in Binary THF−H2 Clathrate Hydrates

Hydrogen Molecule in the Small Dodecahedral Cage of a Clathrate Hydrate: Quantum Five-Dimensional Calculations of the Coupled Translation−Rotation Eigenstates

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Molecular Hydrogen Occupancy in Binary THF−H₂ Clathrate Hydrates by High Resolution Neutron Diffraction

Molecular Hydrogen Occupancy in Binary THF−H₂ Clathrate Hydrates by High Resolution Neutron Diffraction

Molecular Hydrogen Storage in Binary THF−H₂ Clathrate Hydrates