Preservation of carbon dioxide clathrate hydrate at temperatures below the water freezing point under atmospheric pressure

This paper reports the experimental study on the preservation of CO ₂ hydrate crystal samples at domestic freezer conditions for 3 weeks. These samples were characterized by initial hydrate mass fractions of 0.95 and 0.50, by particle diameters of smaller than 2.8, 2.8-4.0, and 5.6-8.0 mm and greater than 8.0 mm, and also by preservation temperatures at 258 and 253 K. The results revealed that the stability of CO ₂ hydrate depends on the particle size, the initial hydrate mass fractions in the samples, and the preservation temperatures. Better stability was observed for CO ₂ hydrate crystal samples of larger particle size and lower initial hydrate fraction and preserved at lower temperature. Visual observations of CO ₂ hydrate crystal samples showed that dissociation occurs on the surface of the crystal samples. These experimental results indicated the possibility of the development of novel food/drink products containing CO ₂ hydrate.