(203f) From Time-Independent Thermodynamic Measurements Towards Time-Dependent Kinetic Measurements On Hydrogen Clathrate Hydrates

Clathrate hydrates are crystalline structures, composed by ice lattices, with well defined cages, formed by hydrogen-bonded water molecules in which guest molecules can be entrapped and stabilized. The potential of these compounds to store hydrogen was first described by Mao et al.[1] They showed that hydrogen clathrate hydrate could be stabilized at extreme conditions only, i.e. at pressures up to 230 MPa. Florusse et al.[2] proved that the application of a second guest molecule, the promoter, made it possible to stabilize the hydrogen clathrate hydrate at pressures lower than 10 MPa. The search for new materials that are able to store hydrogen in molecular form within a water clathrate framework at low pressures and near ambient is of great interest to explore the possibility of using these solids as a safe hydrogen storage method for transportation. Nonetheless, another extremely important question concerns the kinetics of formation and decomposition of gas hydrates. The most challenging area in hydrates is to move beyond the time-independent thermodynamics, to time-dependent kinetic measurements. Two questions are essential for a better knowledge of gas hydrates: (i) when will the hydrates be formed and (ii) how fast will they dissociate.[3] In this work, novel phase behaviour measurements on binary hydrate systems promoter + H2 are reported. In addition, kinetic results on the formation and decomposition of the same binary systemare reported as well.

[1]Mao, W. L., et al., Science, 297 (2002), 2247-2249 [2]Florusse, et al., Science, 306 (2004) 469-471 [3]Sloan, E. D., Clathrate Hydrates of Natural Gases, Marcel Dekker, New York, ed. 2, 1998