Influence of surface wettability on methane hydrate formation in hydrophilic and hydrophobic mesoporous silicas

Casco, M.E. and Grätz, S. and Wallacher, D. and Grimm, N. and Többens, D.M. and Bilo, M. and Speil, N. and Fröba, M. and Borchardt, L.

Volume: 405 Pages:
DOI: 10.1016/j.cej.2020.126955
Published: 2021

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. © 2020 Elsevier B.V.

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