A dynamic study of the formation of gas clathrate hydrates: In-situ synchrotron x-ray diffraction and differential scanning calorimetry

A novel in-situ time-resolved synchrotron x-ray diffraction technique has been applied to the study of the dynamic processes occurring during the formation and decomposition of propane and carbon dioxide clathrate hydrates. Our x-ray results provide clear evidence on the presence of micro-crystalline intermediate structures during gas adsorption and desorption. The in-situ crystal lattice parameters of the enclathrated propane and carbon dioxide molecules were found to be 1.192nm and 1.7196nm respectively. The parameter for propane is lower than the value predicted from previous low temperature, single crystal data and shows that the pressure and temperature conditions during gas clathrate hydrate formation has some effect on the structure of the host lattice which incorporates the gas molecules. In-situ differential scanning calorimetry has provided complementary thermodynamic and kinetic data during hydrate formation and dissociation.