Physical-chemistry of gas hydrates: from geo/astrophysics to new opportunities for energy technologies

QUICK INFORMATION
Type
ILL-ESRF Colloquium
Start Date
06-12-2019 14:00
End Date
06-12-2019 15:30
Location
ILL Chadwick Amphitheatre
Speaker's name
Arnaud Desmedt
Speaker's institute
Groupe Spectroscopie Moléculaire, ISM UMR5255 CNRS, University of Bordeaux
Contact name
Eva Jahn
Host name
Ulli Koesnter, Partrick Bruno
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Gas hydrates are ice-like systems made of a network of hydrogen-bonded water molecules (forming host cages) that is stabilized by the presence of foreign guest molecules [1]. The natural existence of large quantities of hydrocarbon hydrates in deep oceans and permafrost is certainly at the origin of numerous applications in areas such as energy, geophysics sciences and innovative technologies [2]. Their hypothetical occurrence in extraterrestrial objects (planets, comets and planetesimal) is also the subject of numerous researches in astrophysics [3]. At a fundamental level, their nanostructuration confers on these materials specific properties (e.g. molecular selectivity, transport properties) for which the host-guest interactions play a key role [4,5]. These interactions occur on a broad timescale and thus require the use of a multi-technique approach (Neutron scattering, Raman, NMR, Classical and ab-initio Molecular Dynamics Simulations). The presentation will review recent results obtained on the physical chemistry of clathrate hydrates towards two main issues - for which neutron scattering brings significant contributions: gas selectivity and structural metastability on one hand, and super-protonic conduction on the other hand.

Recent theoretical works suggest that the nitrogen depletion observed on the Jupiter family comet 67P/Churyumov-Gerasimenko might be due to preferential encapsulation of carbon monoxide with respect to nitrogen inside mixed gas hydrate [6]. The presentation will report the first experimental investigations of such a preferential trapping, together with unusual structural metastability, as revealed by means of Raman scattering, Neutron diffraction and Quantum Mechanics calculations in various mixed gas (CO, CO2, N2) hydrates [7-13].

In addition to gaseous species, clathrate hydrates may encapsulate strong acids. Such supramolecular assembly leads to generate super-protonic conductors (i.e. with protonic conduction of the order of 0.1S/cm) [14]. Quasi-elastic neutron scattering is a unique technique for disentangling the proton transport mechanism involved in such ice-like systems [15,16]. This issue will be reviewed by outlining the contributions of Neutron scattering together with complementary techniques such as ab-initio Molecular Dynamics, Raman imaging or pulsed-field gradient proton NMR. Moreover, new opportunities in the area of energy (electrochemical energy production [17] and hydrogen storage [18-20]) are offered thanks to the strong acidic character of clathrate hydrates. These points will be outlined.

 

[1] E. D. Sloan and C. A. Koh, Clathrate Hydrates of natural gases, Taylor & Francis-CRC Press, Boca Raton, FL, 3rd edn, 2008.

[2] L. Ruffine, D. Broseta, A. Desmedt, Eds, Gas Hydrates 2: Geoscience Issues and Potential Industrial Applications, Wiley: London (2018).

[3] e.g. G. Tobie et al, Nature 2006, 440, P.61 // Nature 2015, 519, p.162.

[4] D. Broseta, L. Ruffine, A. Desmedt, Eds, Gas hydrates 1: Fundamentals, Characterization and Modeling, Wiley: London (2017)

[5] A. Desmedt, et al. Eur. Phys. J. Special Topics 213 (2012) 103-127

[6] S. Lectez, et al, Astrophys. J. Lett., 2015, 805: L1.

[7] C. Petuya, et al, J. Phys. Chem. C 121(25) (2017) 13798–13802.

[8] C. Petuya, et al, J. Phys. Chem. C 122(1) (2018) 566 –573.

[9] C. Petuya, et al, Crystals 8 (2018) 145(1-13).

[10] C. Petuya, et al, Chem. Comm. 54 (2018) 4290-4293.

[11] C. Petuya, et al, J. Phys. Chem. C 123(8) (2019) 4871-4878.

[12] C. Petuya, et al, J. Chem. Phys. 150(18) (2019) 184705.

[13] C. Métais, et al, in preparation.

[14] J. Cha, et al. J. Phys. Chem. C 2008, 112, 13332−13335.

[15] L. Bedouret, et al, J. Phys. Chem. B 118 (2014) 13357−13364.

[16] A. Desmedt, et al, Solid State Ionics, 252 (2013) 19-25

[17] S. Desplanche et al, article in preparation // A. Desmedt, S. Desplanche et al, Patent FR 18 53886 (2018).

[18] E. Pefoute, et al, J. Phys. Chem. C 116(32) (2012) 16823

[19] A. Desmedt, et al, J. Phys. Chem. C 119 (2015) 8904-8911

[20] T.T. Nguyen, et al, in preparation.

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