Storage of H₂ in Clathrate Hydrates: Evaluation of Different Force-Fields used in Monte Carlo Simulations

ABSTRACT

In the current study, we report an extensive series of Grand Canonical Monte Carlo simulations of H₂ hydrates at pressures up to 500 MPa. The study examines the three most common hydrate structures (sI, sII, and sH). The average occupancy is calculated individually for each cavity by considering the enclathration mechanism as a process of gas adsorption in a porous solid. The correlation between chemical potential and pressure is determined through NVT Monte Carlo simulations. Simulations are performed for three water models (SPC/E, TIP4P/Ice, and TIP5P); the effect of quantum behaviour of H₂ is also examined. In terms of engineering-type practical calculations, all of the examined models give similar results concerning the H₂ content of the hydrate. Finally, the calculated cage occupancy values are utilised for the prediction of H₂ content in hydrate systems with promoters (H₂ + tetrahydrofuran) and an extensive comparison with experimental values is reported with good agreement between calculations and experiments.

KEYWORDS:

• Clathrate hydrate
• Grand Canonical Monte Carlo
• cavity occupancy
• H₂ hydrate
• gas storage capacity
• Langmuir absorption

Acknowledgments

This publication was made possible thanks to an NPRP award [NPRP 615472632] from the Qatar National Research Fund (a member of The Qatar Foundation). The statements made herein are solely the responsibility of the authors. N.I. Papadimitriou gratefully acknowledges the Greek Scholarship Foundation for the financial support under the IKY Siemens program [Contract No. SR 22071/13]. We are grateful to the High Performance Computing Cluster of the Environmental Research Laboratory (NCSR ‘Demokritos’) for generous computational resource allocation.

Disclosure statement

No potential conflict of interest was reported by the authors.

Additional information

Funding

This publication was made possible thanks to an NPRP award [NPRP 6–1547–2–632] from the Qatar National Research Fund (a member of The Qatar Foundation).