Formation of gas hydrates in the systems methane-water-ROH (ROH = ethanol, n-propanol, i-propanol, i-butanol)

Numerical data on the decomposition curves of gas hydrates formed by methane and aqueous solutions of ethanol (with the concentration up to 24 mol%), isopropanol (concentration: up to 42 mol%), n-propanol (concentration: up to 32 mol%) and isobutanol (up to the saturated aqueous solution) are presented. Investigations were carried out within the pressure range 1-16 MPa. It has been found that hydrate formation occurs in a specific manner for each of these systems and no general regularities are observed. Ethanol acts as an inhibitor of hydrate formation; however, for a given molar concentration the decrease in the temperature of hydrate formation is smaller for ethanol than for methanol. Isopropanol and n-propanol form double hydrates with methane; decomposition temperatures of these hydrates differ insignificantly from each other and from the decomposition temperature of the hydrate of pure methane. Finally, decomposition temperatures of the hydrates formed by aqueous isobutanol solutions are lower in comparison with the hydrate formed by pure methane. (C) 2009 Elsevier Ltd. All rights reserved.