Stability of methane hydrate at high-pressure and high-temperature of up to 40 GPa and 573 K

High-pressure and high-temperature experiments were performed to investigate the stability of methane hydrate under 6-40 GPa and 298-573 K using synchrotron X-ray powder diffraction in combination with a diamond anvil cell. The results thus obtained revealed that methane hydrate decomposes into solid methane and ice VII at temperatures considerably lower than the melting curves of solid methane and ice VII in the pressure range of 6-40 GPa.