NMR evidence of supercooled water formation during gas hydrate dissociation below the melting point of ice

Preliminary results are presented on the use of nuclear magnetic resonance (NMR) relaxation spectroscopy for analysis of water phase transformations during dissociation of gas hydrate dispersions below 273 K. Freon-12 hydrates formed a cubic structure II were used for model studies without need for high pressure. Freon hydrates were formed from micron-sized water droplets with an average radius of about 5 μm dispersed in polyethylsiloxane fluid (PES-5). This research demonstrates the possibility of using NMR relaxation spectroscopy to study phase transformations of water in gas hydrate systems at temperatures below 273 K, including the region of their metastable states on the P–T phase diagram below the ice–hydrate–gas equilibrium pressure.

► Gas hydrate dissociation at temperature below 273 K was studied by 1H NMR. ► New evidences of supercooled water formation during hydrate dissociation. ► Thermal history of gas hydrates influences on mechanism of hydrate dissociation.