In situ high-pressure NMR observations on the formation and dissociation of methane hydrate

A home-made static NMR cell with pressure up to 10 MPa was employed to observe the formation and dissociation processes of methane hydrate by in situ H-1 and C-13 NMR spectroscopies. Methane hydrate can be formed or decomposed in the temperature range of -5 to -13 degrees C at pressures between 4.0 and 7.0 MPa. The higher methane pressure, the formation or dissociation temperature of methane hydrate was higher. In situ H-1 NMR experiments indicated that the critical size of the hydrate clusters is crucial for the formation of methane hydrate.