Issue 48, 2015

Effects of thermodynamic inhibitors on the dissociation of methane hydrate: a molecular dynamics study

Abstract

We investigate the effects of methanol and NaCl, which are known as thermodynamic hydrate inhibitors, on the dissociation kinetics of methane hydrate in aqueous solutions by using molecular dynamics simulations. It is shown that the dissociation rate is not constant but changes with time. The dissociation rate in the initial stage is increased by methanol whereas it is decreased by NaCl. This difference arises from the opposite effects of the two thermodynamic inhibitors on the hydration free energy of methane. The dissociation rate of methane hydrate is increased by the formation of methane bubbles in the aqueous phase because the bubbles absorb surrounding methane molecules. It is found that both methanol and NaCl facilitate the bubble formation. However, their mechanisms are completely different from each other. The presence of ions enhances the hydrophobic interactions between methane molecules. In addition, the ions in the solution cause a highly non-uniform distribution of dissolved methane molecules. These two effects result in the easy formation of bubbles in the NaCl solution. In contrast, methanol assists the bubble formation because of its amphiphilic character.

Graphical abstract: Effects of thermodynamic inhibitors on the dissociation of methane hydrate: a molecular dynamics study

Article information

Article type
Paper
Submitted
25 May 2015
Accepted
09 Nov 2015
First published
11 Nov 2015

Phys. Chem. Chem. Phys., 2015,17, 32347-32357

Author version available

Effects of thermodynamic inhibitors on the dissociation of methane hydrate: a molecular dynamics study

T. Yagasaki, M. Matsumoto and H. Tanaka, Phys. Chem. Chem. Phys., 2015, 17, 32347 DOI: 10.1039/C5CP03008K

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