Solubility of Aqueous Methane under Metastable Conditions: Implications for Gas Hydrate Nucleation
- 14 May 2013
- journal article
- research article
- Published by American Chemical Society (ACS) in The Journal of Physical Chemistry B
- Vol. 117 (21), 6498-6504
- https://doi.org/10.1021/jp3117215
Abstract
To understand the prenucleation stage of methane hydrate formation, we measured methane solubility under metastable conditions using molecular dynamics simulations. Three factors that influence solubility are considered: temperature, pressure, and the strength of the modeled van der Waals attraction between methane and water. Moreover, the naturally formed water cages and methane clusters in the methane solutions are analyzed. We find that both lowering the temperature and increasing the pressure increase methane solubility, but lowering the temperature is more effective than increasing the pressure in promoting hydrate nucleation because the former induces more water cages to form while the latter makes them less prevalent. With an increase in methane solubility, the chance of forming large methane clusters increases, with the distribution of cluster sizes being exponential. The critical solubility, beyond which the metastable solutions spontaneously form hydrate, is estimated to be ∼0.05 mole fraction in this work, corresponding to the concentration of 1.7 methane molecules/nm3. This value agrees well with the cage adsorption hypothesis of hydrate nucleation.This publication has 30 references indexed in Scilit:
- Nucleation Pathways of Clathrate Hydrates: Effect of Guest Size and SolubilityThe Journal of Physical Chemistry B, 2010
- Amorphous Precursors in the Nucleation of Clathrate HydratesJournal of the American Chemical Society, 2010
- Hydrate formation and re-formation in nucleating THF/water mixtures show no evidence to support a “memory” effectChemical Engineering Journal, 2010
- Observation of two-step nucleation in methane hydratesPhysical Chemistry Chemical Physics, 2010
- Microsecond Simulations of Spontaneous Methane Hydrate Nucleation and GrowthScience, 2009
- Gas hydrate nucleation and cage formation at a water/methane interfacePhysical Chemistry Chemical Physics, 2008
- Search for memory effects in methane hydrate: Structure of water before hydrate formation and after hydrate decompositionThe Journal of Chemical Physics, 2005
- NMR/MRI Study of Clathrate Hydrate MechanismsThe Journal of Physical Chemistry B, 2005
- Molecular Dynamics Study of Gas Hydrate FormationJournal of the American Chemical Society, 2003
- Methane Hydrate: Melting and MemoryAnnals of the New York Academy of Sciences, 2000