Characterization of gas hydrates by Modulated Differential Scanning Calorimetry

Modulated Differential Scanning Calorimetry (MDSC) has been applied to the study of methane, ethane, and propane hydrates at different hydrate and ice concentrations. The reversing thermodynamical component of the MDSC curves, makes it possible to characterize such hydrates. Methane and ethane hydrates show the melting-decomposition peak at a temperatures higher than the ice contained in the sample, while propane hydrate melts and decomposes at a lower temperature than the ice present in the sample. The hydrate peaks tend to disappear if the hydrate is stored at atmospheric pressure. Guest size and cavity occupation fix the heat of dissociation and stability of the hydrates, as confirmed by parallel tests on tetrahydrofurane hydrates.