Vertical Growth of Methane Hydrate Films on Glass during the Formation of Hydrates from Surfactant Solutions

The morphology of methane hydrates formed on the vertical walls of a glass cuvette from solutions of six surfactants has been studied using visual observations. Hexadecyltrimethylammonium bromide and benzyldimethylhexadecylammonium chloride were found to be particularly conducive to the formation of hydrate films. The film growth rate in solutions of these surfactants can reach ∼0.02 mm/s, and the degree of wall coverage can be close to 100%. The formation of the hydrate film on vertical cuvette walls as well as the growth of loose hydrate mass filling the entire cell volume were observed in sodium 1-octanesulfonate and sodium n-dodecylsarcosinate solutions. The growth on the walls was weakly expressed in the case of sodium n-dodecylsarcosinate solution. The rate of hydrate film growth was 3 orders of magnitude lower. In experiments with didodecyldimethylammonium bromide solutions, hydrate films did not form on the walls. A possible mechanism for the formation of these films is discussed. It is hypothesized that adsorption of the surfactant weakens the hydrate’s adhesion to the walls, leading to the formation of a streak of water–gas contact on the boundary between the hydrate and the cuvette wall. Hydrate formation in this streak promotes the growth of the hydrate film.