Contribution of water molecules to methane hydrate dissociation

In this report, we describe the effects of ice on the restriction of methane diffusion during the dissociation of pressurized methane hydrate grains using two deuterium-labelling approaches with D 2 O. Direct measurements of the dissociation behaviors of the methane hydrate samples labelled by a temperature ramping method at temperatures of 253.0–293.0 K were carried out. The deuterium-labelling approaches demonstrated that water molecules in the host framework of methane hydrate predominantly contribute to ice formation, which restricts methane release from the decomposing hydrate framework more than ice coexisting with methane hydrate. The shielding effect of ice in intimate contact with methane hydrate particles on methane diffusion during the decomposition of the hydrate framework depends on the ratio of preexisting ice in the methane hydrate sample.