X-ray synchrotron diffraction study of natural gas hydrates from African margin - art. no. L22303

Type Article
Date 2007-11
Language English
Author(s) Bourry Christophe1, Charlou Jean-Luc1, Donval Jean-Pierre1, Brunelli M2, Focsa C3, Chazallon B3
Affiliation(s) 1 : IFREMER, Brest Ctr, Dept Geosci Marines, Lab Geochimie Met, Plouzane, France.
2 : European Synchrotron Radiat Facil, F-38043 Grenoble, France.
3 : Univ Lille 1, CNRS, UMR, Phys Lasers Lab, F-8523 Villeneuve, France.
Source Geophysical Research Letters ( GRL ) (0094-8276) (American Geophysical Union), 2007-11 , Vol. 34 , N. 22 , P. NIL_46-NIL_50
DOI 10.1029/2007GL031285
WOS© Times Cited 8
Keyword(s) synchrotron X ray diffraction, thermal expansion, natural clathrate hydrates
Abstract Natural gas hydrates recovered from the Congo- Angola basin and Nigerian margins are analyzed by synchrotron X- ray powder diffraction. Biogenic methane is the most abundant gas trapped in the samples and others minor components (CO2, H2S) are co-clathrated in a type I cubic lattice structure. The refinement for the type I structure gives lattice parameters of a = 11.8646 ( 39) angstrom and a = 11.8619 ( 23) angstrom for specimens from Congo- Angola and Nigerian margins respectively at 90 K. These values, intermediate between the lattice constant of less pure methane specimens and pure artificial methane hydrates, indicate that lattice constants can be affected by the presence of encaged CO2, H2S and other gas molecules, even in small amounts. Thermal expansion is also presented for Congo- Angola hydrate in the temperature range 90 - 200 K. The coefficients are comparable with values reported for synthetic hydrates at low temperature and tend to approach thermal expansion of ice at higher temperature.
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Bourry Christophe, Charlou Jean-Luc, Donval Jean-Pierre, Brunelli M, Focsa C, Chazallon B (2007). X-ray synchrotron diffraction study of natural gas hydrates from African margin - art. no. L22303. Geophysical Research Letters ( GRL ), 34(22), NIL_46-NIL_50. Publisher's official version : https://doi.org/10.1029/2007GL031285 , Open Access version : https://archimer.ifremer.fr/doc/00000/3511/