Gas hydrates are very attractive from both resources and environmetnal aspects. CO2 gas hydrate can be utilized to develop methane gas hydrate as an important energy source in the near future. The kinetics of CO2 hydrate formation below melting point of ice was studied. The nucleation phenomena or mechanism of CO2 gas hydrate formation changed around the melting point of ice. The formation of gas hydrate was very fast in the first stage of time growth within 200 min. However, the rate of formation became slower in the second stage of time growth. The thickness of the layer depended on the condition of temperature and ice surface. On the contrary, the controlled factor might be the diffusion coefficient of gas between ice and hydrate because the rate of formation became slower with time due to the blocking of gas transport through media. These kinetic data and the mechanisms of crystal growth were very important to evaluate the formation behaviors of CO2 gas hydrates under the real environment, e.g., marine sediments and permafrost. The effect of temperature on the gas hydrate formation was nonlinear and singular.
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