| Summary: | The methane hydrate MH formation process in confinement was investigated using high pressure methane sorption experiments on two wet materials with similar pore size distributions, B PMO hydrophobic and MCM 41 hydrophilic . Their methane sorption isotherms possess two discrete methane gas consumption steps at 10 bar and 30 bar at 243 K. A systematic analysis reveals that external water and the so called core water inside the pore is rapidly consumed in the first step to form bulk like hydrate, whereas adsorbed water is slowly consumed in the second step to form less stable confined hydrates at higher pressures. Synchrotron powder X Ray results confirm methane hydrate structure I and reveal that bulk ice is swiftly and fully converted to hydrate in MCM 41, whereas inactive bulk ice co exists with MH in B PMO at 6 MPa demonstrating the huge impact of the surface wettability on the water s behavior during MH formation
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