Phase equilibria in the H2O-CO2 system between 250-330 K and 0-1.7 GPa: Stability of the CO2 hydrates and H2O-ice VI at CO2 saturation

Research areas:

• Intérieurs planétaires (2011 - 2016)

Year:

2013

Authors:

• Olivier Bollengier
• Mathieu Choukroun
• Olivier Grasset
• Guillaume Bellino
• Erwan Le Menn
• Yann Morizet
• Lucile Bezacier
• Adriana Oancea
• Cécile Taffin
• Gabriel Tobie

Journal:

GEOCHIMICA ET COSMOCHIMICA ACTA

Volume:

119

Pages:

322-339

Month:

OCT 15

ISSN:

0016-7037

BibTex:

@article{WOS:000324036200021, author = "Olivier Bollengier and Mathieu Choukroun and Olivier Grasset and Guillaume Bellino and Erwan Le Menn and Yann Morizet and Lucile Bezacier and Adriana Oancea and C{\'e}cile Taffin and Gabriel Tobie", abstract = "Although carbon dioxide is of interest in planetary science, few studies have been devoted so far to the H2O-CO2 system at pressures and temperatures relevant to planetary interiors, especially of the icy moons of the giant planets. In this study, new sapphire and diamond anvil cell experiments were conducted in this binary system to constrain the stability of the CO2 hydrates and H2O-ice VI at CO2 saturation in the 250-330 K and 0-1.7 GPa temperature and pressure ranges. Phases and equilibria were characterized by in situ Raman spectroscopy and optical monitoring. The equilibrium between the CO2 sI clathrate hydrate and the H2O-rich liquid phase was constrained over the entire pressure range of stability of the hydrate, up to 0.7-0.8 GPa, with results in agreement with previous studies at lower pressures. Above this pressure and below 1 GPa, our experiments confirmed the existence of the new CO2 high-pressure hydrate reported recently. Finally, the melting curve of the H2O-ice VI at CO2 saturation in the absence of CO2 hydrates was determined between 0.8 and 1.7 GPa. Using an available chemical potential model for H2O, a first assessment of the solubility of CO2 along the H2O-ice VI melting curve is given. Consistent with these new results and previous studies of the H2O-CO2 system, a P-T-X description of the binary system is proposed. The evolution with pressure of the Raman signatures of the two CO2 hydrates is detailed, and their stability is discussed in light of other clathrate hydrate-forming systems. (C) 2013 Elsevier Ltd. All rights reserved.", doi = "10.1016/j.gca.2013.06.006", extra = "PICL", issn = "0016-7037", journal = "GEOCHIMICA ET COSMOCHIMICA ACTA", month = "OCT 15", pages = "322-339", title = "{P}hase equilibria in the {H}2{O}-{CO}2 system between 250-330 {K} and 0-1.7 {GP}a: {S}tability of the {CO}2 hydrates and {H}2{O}-ice {VI} at {CO}2 saturation", volume = "119", year = "2013", }

Abstract:

Although carbon dioxide is of interest in planetary science, few studies
have been devoted so far to the H2O-CO2 system at pressures and
temperatures relevant to planetary interiors, especially of the icy
moons of the giant planets. In this study, new sapphire and diamond
anvil cell experiments were conducted in this binary system to constrain
the stability of the CO2 hydrates and H2O-ice VI at CO2 saturation in
the 250-330 K and 0-1.7 GPa temperature and pressure ranges. Phases and
equilibria were characterized by in situ Raman spectroscopy and optical
monitoring. The equilibrium between the CO2 sI clathrate hydrate and the
H2O-rich liquid phase was constrained over the entire pressure range of
stability of the hydrate, up to 0.7-0.8 GPa, with results in agreement
with previous studies at lower pressures. Above this pressure and below
1 GPa, our experiments confirmed the existence of the new CO2
high-pressure hydrate reported recently. Finally, the melting curve of
the H2O-ice VI at CO2 saturation in the absence of CO2 hydrates was
determined between 0.8 and 1.7 GPa. Using an available chemical
potential model for H2O, a first assessment of the solubility of CO2
along the H2O-ice VI melting curve is given. Consistent with these new
results and previous studies of the H2O-CO2 system, a P-T-X description
of the binary system is proposed. The evolution with pressure of the
Raman signatures of the two CO2 hydrates is detailed, and their
stability is discussed in light of other clathrate hydrate-forming
systems. (C) 2013 Elsevier Ltd. All rights reserved.