Phase Behavior of CO2 and CH4 Hydrate in Porous Media

Hydrate phase equilibria for the binary CO2+water and CH4+water mixtures in silica gel pore of nominal diameters 6, 30, and 100 nm were measured and compared with the calculated results based on van der Waals and Platteeuw model. At a specific temperature, three-phase hydrate-water-vapor (HLV) equilibrium curves for pore hydrates were shifted to the higher-pressure condition depending on pore sizes when compared with those of bulk hydrates. Notably, hydrate phase equilibria for the case of 100 nominal nm pore size were nearly identical with those of bulk hydrates. The activities of water in porous silica gels were modified to account for capillary effect, and the calculation results were generally in good agreement with the experimental data. The structural characteristics of gas hydrates in silica gel pores were investigated through NMR spectroscopy.




References:
[1] E. D. Sloan, Clathrate Hydrates of Natural Gas, 2nd ed., New York:
Dekker, 1998.
[2] H. Teng, A. Yamasaki, M.-K. Chun, and H. Lee, "Why does CO2 hydrate
disposed of in the ocean in the hydrate-formation region dissolve in
seawater?," Energy, vol. 22, no. 12, pp1111-1117, 1997.
[3] Y. P. Handa, and D. Stupin, "Thermodynamic properties and dissociation
characteristics of methane and propane hydrates in 70-Å-radius silica gel
pores," J. Phys. Chem., vol. 96, no. 21, pp8599-8603, 1992.
[4] T. Uchida, T. Ebinuma, and T. Ishizaki, "Dissociation condition
measurements of methane hydrate in confined small pores of porous
glass," J. Phys. Chem. B, vol. 103, no. 18, pp3659-3662, 1999.
[5] T. Uchida, T. Ebinuma, S. Takeya, J. Nagao, and H. Narita, "Effects of
pore sizes on dissociation temperatures and pressures of methane, carbon
dioxide, and propane hydrates in porous media," J. Phys. Chem. B, vol.
106, no. 4, pp820-826, 2002.
[6] J. W. Wilder, K. Seshadri, and D. H. Smith, "Modeling hydrate formation
in media with broad pore size distribution," Langmuir, vol. 17, no. 21,
pp6729-6735, 2001.
[7] J. W. Wilder, K. Seshadri, and D. H. Smith, "Resolving apparent
contradictions in equilibrium measurements for clathrate hydrates in
porous media," J. Phys. Chem. B, vol. 105, no. 41, pp9970-9972, 2001.
[8] K. Seshadri, J. W. Wilder, and D. H. Smith, "Measurements of
equilibrium pressures and temperatures for propane hydrate in silica gels
with different pore-size distributions," J. Phys. Chem. B, vol. 105, no. 13,
pp2627-2631, 2001.
[9] D. H. Smith, J. W. Wilder, and K. Seshadri, "Methane hydrate equilibria
in silica gels with broad pore-size distributions," AIChE J., vol. 48, no. 2,
pp393-400, 2002.
[10] W. Zhang, J. W. Wilder, and D. H. Smith, "Interpretation of ethane
hydrate equilibrium data for porous media involving hydrate-ice
equilibria," AIChE J., vol. 48, no. 10, pp2324-2331, 2002.
[11] P. Henry, M. Thomas, and M. B. Clennell, "Formation of natural gas
hydrates in marine sediments 2. Thermodynamic calculations of stability
conditions in porous sediments," J. Geophys. Res. B, vol. 104, no. B10,
pp23005-23022, 1999.
[12] M. A. Clarke, M. Pooladi-Darvish, and P. R. Bishnoi, "A method to
predict equilibrium conditions of gas hydrate formation in porous media,"
Ind. Eng. Chem. Res., vol. 38, no. 6, pp2485-2490, 1999.
[13] Y.-T. Seo, I. L. Moudrakovski, J. A. Ripmeester, J.-W. Lee, and H. Lee,
"Efficient recovery of CO2 from flue gas by clathrate hydrate formation in
porous silica gels," Environ. Sci. Technol., vol. 39, no. 7, pp2315-2319,
2005.
[14] R. Anderson, M. Llamedo, B. Tohidi, and R. W. Burgass, "Characteristics
of clathrate hydrate equilibria in mesopores and interpretation of
experimental data," J. Phys. Chem. B, vol. 107, no. 15, pp3500-3506,
2003.
[15] V. McKoy and O. Sinanoglu, "Theory of dissociation pressures of some
gas hydrates," J. Chem. Phys., vol. 38, no. 12, pp2946-2956, 1963.
[16] G. D. Holder, G. Corbin, and K. D. Papadopoulos, "Thermodynamic and
molecular properties of gas hydrates from mixtures containing methane,
argon, and krypton," Ind. Eng. Chem. Fund., vol. 19, no. 3, pp282-286,
1980.
[17] R. Anderson, M. Llamedo, B. Tohidi, and R. W. Burgass, "Experimental
measurement of methane and carbon dioxide clathrate hydrate equilibria
in mesoporous silica," J. Phys. Chem. B, vol. 107, no. 15, pp3507-3514,
2003.
[18] Y. Seo, H. Lee, and T. Uchida, "Methane and carbon dioxide hydrate
phase behavior in small porous silica gels: three-phase equilibrium
determination and thermodynamic modeling," Langmuir, vol. 18, no. 24,
pp9164-9170, 2002.
[19] Y. Seo and H. Lee, "A new hydrate-based recovery process for removing
chlorinated hydrocarbons from aqueous solutions," Environ. Sci. Technol.,
vol. 35, no. 16, pp3386-3390, 2001.
[20] S.-P. Kang and H. Lee, "Recovery of CO2 from flue gas using gas hydrate:
thermodynamic verification through phase equilibrium measurements,"
Environ. Sci. Technol., vol. 34, no. 20, pp4397-4400, 2000.