NMR studies on CH4+CO2 binary gas hydrates dissociation behavior

The dissociation behavior of the CH4+CO2 binary gas hydrate has been investigated using Nuclear Magnetic Resonance (NMR) spectroscopy. This technique allows us to distinguish the hydrate structure present, as well as to quantify phase concentrations. Single-pulse excitation was used in combination with magic-angle spinning (MAS). Time-resolved in situ decomposition experiments were carried out at different compositions in sealed, pressurized samples. The decomposition profiles of the CH4+CO2 binary gas hydrate system obtained at various compositions suggest that the decomposition rate is a strong function of the fractional cage occupancy and temperature. An unexpected CH4 hydrate reformation was observed during our decomposition experiments when the temperature reached the ice melting point. A decrease on the CO2 content in the hydrate phase was found during the decomposition experiment, as the pressure and temperature of the system increases.