Carbon dioxide clathrate

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Carbon dioxide

clathrate.[2] There has also been some experimental evidence for the development of a metastable Type II phase at a temperature near the ice melting point.[3][4][5] The clathrate can exist below 283K (10 °C) at a range of pressures of carbon dioxide. CO2 hydrates are widely studied around the world due to their promising prospects of carbon dioxide capture from flue gas and fuel gas streams relevant to post-combustion and pre-combustion capture.[6][7][8][9] It is also quite likely to be important on Mars
due to the presence of carbon dioxide and ice at low temperatures.

History

The first evidence for the existence of CO2

MPa).[17] The CO2 hydrate was classified as a Type I clathrate for the first time by von Stackelberg & Muller (1954).[18]

Importance

Earth

In this mosaic taken by the Mars Global Surveyor: Aram Chaos - top left and Iani Chaos - bottom right. A river-bed-like outflow channel can be seen, originating from Iani Chaos and extending towards the top of the image.

On Earth, CO2 hydrate is mostly of academic interest. Tim Collett of the United States Geological Survey (USGS) proposed pumping carbon dioxide into subsurface methane clathrates, thereby releasing the methane and storing the carbon dioxide.[19] As of 2009, ConocoPhillips is working on a trial on the Alaska North Slope with the US Department of Energy to release methane in this way.[20][19] At first glance, it seems that the thermodynamic conditions there favor the existence of hydrates, yet given that the pressure is created by sea water rather than by CO2, the hydrate will decompose.[21] Recently, Professor Praveen Linga and his group in collaboration with ExxonMobil have demonstrated the first-ever experimental evidence of the stability of carbon dioxide hydrate in deep-oceanic sediments.[22][23][24]

Mars

However, it is believed that CO2 clathrate might be of significant importance for planetology. CO2 is an abundant volatile on Mars. It dominates in the atmosphere and covers its polar ice caps much of the time. In the early seventies, the possible existence of CO2 hydrates on Mars was proposed.[25] Recent consideration of the temperature and pressure of the regolith and of the thermally insulating properties of dry ice and CO2 clathrate[26] suggested that dry ice, CO2 clathrate, liquid CO2, and carbonated groundwater are common phases, even at Martian temperatures.[27][28][29]

If CO2 hydrates are present in the Martian polar caps, as some authors suggest,

thermal conductivity, higher stability under pressure, and higher strength,[33]
as compared to pure water ice.

The question of a possible diurnal and annual CO2 hydrate cycle on Mars remains, since the large temperature amplitudes observed there cause exiting and reentering the clathrate stability field on a daily and seasonal basis. The question is, then, can gas hydrate being deposited on the surface be detected by any means? The OMEGA spectrometer on board Mars Express returned some data, which were used by the OMEGA team to produce CO2 and H2O-based images of the South polar cap. No definitive answer has been rendered with respect to Martian CO2 clathrate formation.[citation needed]

The decomposition of CO2 hydrate is believed to play a significant role in the

Martian chaotic terrains.[37] Milton (1974) suggested the decomposition of CO2 clathrate caused rapid water outflows and formation of chaotic terrains.[38] Cabrol et al. (1998) proposed that the physical environment and the morphology of the south polar domes on Mars suggest possible cryovolcanism.[39] The surveyed region consisted of 1.5 km-thick-layered deposits covered seasonally by CO2 frost[40] underlain by H2O ice and CO2 hydrate at depths > 10 m.[25] When the pressure and the temperature are raised above the stability limit, clathrate is decomposed into ice and gases, resulting in explosive eruptions
.

Still a lot more examples of the possible importance of the CO2 hydrate on Mars can be given. One thing remains unclear: is it really possible to form hydrate there? Kieffer (2000) suggests no significant amount of clathrates could exist near the surface of Mars.[41] Stewart & Nimmo (2002) find it is extremely unlikely that CO2 clathrate is present in the Martian regolith in quantities that would affect surface modification processes.[42] They argue that long term storage of CO2 hydrate in the crust, hypothetically formed in an ancient warmer climate, is limited by the removal rates in the present climate.[42] Baker et al. 1991 suggests that, if not today, at least in the early Martian geologic history the clathrates may have played an important role for the climate changes there.[43] Since not too much is known about the CO2 hydrates formation and decomposition kinetics, or their physical and structural properties, it becomes clear that all the above-mentioned speculations rest on extremely unstable bases.

Moons

On Enceladus decomposition of carbon dioxide clathrate is a possible way to explain the formation of gas plumes.[44]

In Europa (moon), clathrate should be important for storing carbon dioxide. In the conditions of the subsurface ocean in Europa, carbon dioxide clathrate should sink, and therefore not be apparent at the surface.[44]

Phase diagram

CO2 hydrate phase diagram. The black squares show experimental data.[45] The lines of the CO2 phase boundaries are calculated according to the Intern. thermodyn. tables (1976). The H2O phase boundaries are only guides to the eye. The abbreviations are as follows: L - liquid, V - vapor, S - solid, I - water ice, H - hydrate.

The hydrate structures are stable at different pressure-temperature conditions depending on the guest molecule. Here is given one Mars-related phase diagram of CO2 hydrate, combined with those of pure CO2 and water.[46] CO2 hydrate has two quadruple points: (I-Lw-H-V) (T = 273.1 K; p = 12.56 bar or 1.256 MPa) and (Lw-H-V-LHC) (T = 283.0 K; p = 44.99 bar or 4.499 MPa).[47] CO2 itself has a triple point at T = 216.58 K and p = 5.185 bar (518.5 kPa) and a critical point at T = 304.2 K and p = 73.858 bar (7.3858 MPa). The dark gray region (V-I-H) represents the conditions at which CO2 hydrate is stable together with gaseous CO2 and water ice (below 273.15 K). On the horizontal axes the temperature is given in kelvins and degrees Celsius (bottom and top respectively). On the vertical ones are given the pressure (left) and the estimated depth in the Martian regolith (right). The horizontal dashed line at zero depth represents the average Martian surface conditions. The two bent dashed lines show two theoretical Martian geotherms after Stewart & Nimmo (2002) at 30° and 70° latitude.[42]

References

  1. ISSN 0021-9568
    .
  2. ISBN 978-0-8247-9937-3.[page needed
    ]
  3. ISSN 0021-9568
    .
  4. doi:10.1021/j100162a068
    .
  5. doi:10.1021/jp027787v
    .
  6. doi:10.1021/es001148l
    .
  7. PMID 17689007
    .
  8. doi:10.1016/j.energy.2015.03.103
    .
  9. ^ Herzog, Howard; Meldon, Jerry; Hatton, Alan (April 2009). Advanced Post-Combustion CO2 Capture (PDF) (Report).
  10. ^ Wroblewski, Zygmunt Florenty (1882). "Sur la combinaison de l'acide carbonique et de l'eau" [On the combination of carbonic acid and water]. Comptes Rendus de l'Académie des Sciences (in French). 94: 212–213.
  11. ^ Wroblewski, Zygmunt Florenty (1882). "Sur la composition de l'acide carbonique hydrate" [On the composition of the hydrate of carbonic acid]. Comptes Rendus de l'Académie des Sciences (in French). 94: 254–258.
  12. ^ Wroblewski, Zygmunt Florenty (1882). "Sur les lois de solubilité de l'acide carbonique dans l'eau sous les hautes pressions" [On the laws of solubility of carbonic acid in water at high pressures]. Comptes Rendus de l'Académie des Sciences (in French). 94: 1355–1357.
  13. ^ Villard, M. P. (1884). "Sur l'hydrate carbonique et la composition des hydrates de gaz" [On carbonic hydrate and the composition of gas hydrates]. Comptes Rendus de l'Académie des Sciences (in French). 119. Paris: 368–371.
  14. ^ Villard, M. P. (1897). "Etude expérimentale des hydrates de gaz" [Experimental study of gas hydrates]. Annales de Chimie et de Physique (in French). 11 (7): 289–394.
  15. doi:10.1002/zaac.19251460112
    .
  16. ^ Frost, E. M.; Deaton, W. M. (1946). "Gas hydrate composition and equilibrium data". Oil and Gas Journal. 45: 170–178.
  17. S2CID 220451948
    .
  18. S2CID 93862670
    .
  19. ^ a b Marshall, Michael (26 March 2009). "Ice that burns could be a green fossil fuel". New Scientist.
  20. ^ "Methane Hydrates Production Field Trial" (PDF). ConocoPhillips. 1 October 2008. Archived from the original (PDF) on 20 November 2008.
  21. S2CID 43660951. Archived from the original
    (PDF) on 19 July 2020.
  22. ^ "NUS research shows CO2 could be stored below ocean floor".
  23. ^ "Storing carbon under the seafloor could be possible, study explores how". Archived from the original on 2022-03-14. Retrieved 2022-03-15.
  24. S2CID 245585287
    .
  25. ^
    S2CID 27808378
    .
  26. ISBN 978-94-011-5252-5
    .
  27. doi:10.1016/0019-1035(78)90046-5
    .
  28. ^
    doi:10.1006/icar.2000.6398
    .
  29. Bibcode:2000LPI....31.1891K
    .
  30. S2CID 878373
    .
  31. doi:10.1006/icar.1999.6306
    .
  32. doi:10.1029/94JE02801
    .
  33. Bibcode:1998LPICo.953....8D
    .
  34. S2CID 128618432
    .
  35. S2CID 129028468
    .
  36. doi:10.1029/2002JE001901
    .
  37. S2CID 4418119
    .
  38. S2CID 26421605
    .
  39. Bibcode:1998LPI....29.1249C
    .
  40. Bibcode:1992mars.book..767T
    .
  41. S2CID 129784570
    .
  42. ^
    doi:10.1029/2000JE001465
    .
  43. S2CID 4321529
    .
  44. ^
    S2CID 55958467
    .
  45. ISBN 978-0-8247-9937-3.[page needed
    ]
  46. hdl:11858/00-1735-0000-0006-B57D-6.[page needed
    ]
  47. ISBN 978-0-8247-9937-3.[page needed
    ]
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