Guest Partitioning and Metastability of the Nitrogen Gas Hydrate

Petuya, Claire; Damay, Françoise; Chazallon, Bertrand; Bruneel, Jean-Luc; Desmedt, Arnaud

Document type :

Compte-rendu et recension critique d'ouvrage

DOI :

10.1021/acs.jpcc.7b10151

Title :

Guest Partitioning and Metastability of the Nitrogen Gas Hydrate

Author(s) :

Petuya, Claire [Auteur]
Jet Propulsion Laboratory [JPL]
Institut des Sciences Moléculaires [ISM]
Damay, Françoise [Auteur]
LLB - Nouvelles frontières dans les matériaux quantiques [NFMQ]
Laboratoire Léon Brillouin [LLB - UMR 12]
Chazallon, Bertrand [Auteur]

Physique Moléculaire aux Interfaces [PMI]
Laboratoire de Physique des Lasers, Atomes et Molécules - UMR 8523 [PhLAM]
Bruneel, Jean-Luc [Auteur]
Centre National de la Recherche Scientifique [CNRS]
Institut des Sciences Moléculaires [ISM]
Desmedt, Arnaud [Auteur]
Institut des Sciences Moléculaires [ISM]

Journal title :

Journal of Physical Chemistry C

Pages :

566-573

Publisher :

American Chemical Society

Publication date :

2017-12-19

ISSN :

1932-7447

HAL domain(s) :

Physique [physics]
Chimie

English abstract : [en]

Gas clathrate hydrates or gas hydrates are made of H-bonded water molecules forming cages, within which gaseous (guest) molecules are encapsulated. The formed clathrate structures, which may be metastable, depend on the ...
Show more >Gas clathrate hydrates or gas hydrates are made of H-bonded water molecules forming cages, within which gaseous (guest) molecules are encapsulated. The formed clathrate structures, which may be metastable, depend on the nature and on the partitioning of the guest molecules in the water cage. This work focuses on the structural and vibrational properties of nitrogen hydrate in its two clathrate forms (namely, SI and SII) in the thermodynamic ranges 50–200 bar and 150–270 K, together with a comprehensive analysis of the transformation from SI to SII of this gas hydrate. The thermal expansion of both structures has been measured at 1 bar, and the melting of the nitrogen hydrate has been measured at ca. 210 K at 1 bar. Moreover, the SI structure is metastable in the studied pressure region: from time-dependent neutron powder diffraction analysis, it is shown that the SI structure transforms over time to the SII structure with a rate of (1.37 ± 0.17) × 105 s–1 at 100 K and at 1 bar. The transformation is also characterized by an induction time (i.e., the lifetime of the pure SI structure) of 0.49 day. We have also investigated the guest partitioning of the nitrogen hydrate using high-resolution Raman scattering. Vibrational bands of nitrogen molecules encapsulated in large cages are measured at lower wavenumbers than the one associated with encapsulation in small cages (by 1.1 cm–1 in SI and 0.8 cm–1 in SII). In the case of the thermodynamically stable SII phase, the dependence of the guest partitioning has been characterized as a function of the pressure–temperature conditions. Variation of the relative cage filling is demonstrated. While the small cages remain singly occupied according to previous neutron diffraction analysis, this variation is attributed to large cages of the nitrogen hydrate that easily catch or release nitrogen guest molecules. This study thus provides new opportunities for preparing nitrogen gas hydrates with a “targeted” structure and relative cage filling not only by varying the pressure and temperature but also by playing with the structural metastability.Show less >

Language :

Anglais

Popular science :

Non

ANR Project :

Approche Multi-échelle de l'impact d'impuretés minérales sur le piégeage de gaz dans des clathrates hydrates

Collections :

Laboratoire de Physique des Lasers, Atomes et Molécules (PhLAM) - UMR 8523

Source :

Harvested from HAL

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