Nucleation of Methane Hydrate in Surfactant Solutions in Cells Made of Teflon, Stainless Steel, and Glass

Currently, gas hydrate technologies are being developed for storing and transporting gas, separating gas mixtures, etc. This requires the development of methods for large-scale production of gas hydrates. One of the least studied stages in the processes of hydrate production is hydrate nucleation, which in general corresponds to the appearance of the first nucleus of the hydrate phase capable of further growth. In this work, we studied the influence of the reactor wall material and the addition of various surfactants on the nucleation of methane hydrate. It was shown that the material of the reactor walls most significantly affects the rate of methane hydrate nucleation, with a decrease in rates in the series Teflon > glass ≥ stainless steel. It was also shown that nucleation rates change in the presence of various surfactants in solutions. In particular, when moving from an anionic surfactant (sodium dodecyl sulfate) to a cationic surfactant (N-decylpyridinium chloride), the nucleation rate decreases by an order of magnitude. We also discuss possible mechanisms for methane hydrate formation. Analysis of experimental data shows that the process of hydrate nucleation may have a nonclassical mechanism. We made an attempt to mathematically describe the nonclassical mechanism of a hydrate nucleation process. It was shown that the multistage nonclassical nucleation mechanism can lead to a complication of the shape of experimental survival curves characterizing the nucleation of gas hydrates.