TY - JOUR

T1 - Molecular Dynamics Study of Clathrate-like Ordering of Water in Supersaturated Methane Solution at Low Pressure

AU - Belosludov, Rodion V

AU - Gets, Kirill V

AU - Zhdanov, Ravil K

AU - Bozhko, Yulia Y

AU - Belosludov, Vladimir R

AU - Chen, Li-Jen

AU - Kawazoe, Yoshiyuki

N1 - Funding: V.R.B., K.V.G., Z.R.K., Y.Y.B. and L.-J.C. are grateful to the Russian Foundation for Basic Research (project number 21-52-52001) jointly with the Ministry of Science and Technology of Taiwan (grant no. 110-2923-E-002-008-MY3) for funding this research.

PY - 2023/3/26

Y1 - 2023/3/26

N2 - Using molecular dynamics, the evolution of a metastable solution for "methane + water" was studied for concentrations of 3.36, 6.5, 9.45, 12.2, and 14.8 mol% methane at 270 K and 1 bar during 100 ns. We have found the intriguing behavior of the system containing over 10,000 water molecules: the formation of hydrate-like structures is observed at 6.5 and 9.45 mol% concentrations throughout the entire solution volume. This formation of "blobs" and the following amorphous hydrate were studied. The creation of a metastable methane solution through supersaturation is the key to triggering the collective process of hydrate formation under low pressure. Even the first stage (0-1 ns), before the first fluctuating cavities appear, is a collective process of H-bond network reorganization. The formation of fluctuation cavities appears before steady hydrate growth begins and is associated with a preceding uniform increase in the water molecule's tetrahedrality. Later, the constantly presented hydrate cavities become the foundation for a few independent hydrate nucleation centers, this evolution is consistent with the labile cluster and local structure hypotheses. This new mechanism of hydrogen-bond network reorganization depends on the entropy of the cavity arrangement of the guest molecules in the hydrate lattice and leads to hydrate growth.

AB - Using molecular dynamics, the evolution of a metastable solution for "methane + water" was studied for concentrations of 3.36, 6.5, 9.45, 12.2, and 14.8 mol% methane at 270 K and 1 bar during 100 ns. We have found the intriguing behavior of the system containing over 10,000 water molecules: the formation of hydrate-like structures is observed at 6.5 and 9.45 mol% concentrations throughout the entire solution volume. This formation of "blobs" and the following amorphous hydrate were studied. The creation of a metastable methane solution through supersaturation is the key to triggering the collective process of hydrate formation under low pressure. Even the first stage (0-1 ns), before the first fluctuating cavities appear, is a collective process of H-bond network reorganization. The formation of fluctuation cavities appears before steady hydrate growth begins and is associated with a preceding uniform increase in the water molecule's tetrahedrality. Later, the constantly presented hydrate cavities become the foundation for a few independent hydrate nucleation centers, this evolution is consistent with the labile cluster and local structure hypotheses. This new mechanism of hydrogen-bond network reorganization depends on the entropy of the cavity arrangement of the guest molecules in the hydrate lattice and leads to hydrate growth.

UR - https://www.scopus.com/record/display.uri?eid=2-s2.0-85152352670&origin=inward&txGid=f060725f67fac7ccf39722074d2395d4

U2 - 10.3390/molecules28072960

DO - 10.3390/molecules28072960

M3 - Article

C2 - 37049727

VL - 28

JO - Molecules

JF - Molecules

SN - 1420-3049

IS - 7

M1 - 2960

ER -