Thermodynamic model for prediction of phase equilibria of clathrate hydrates of hydrogen with different alkanes, alkenes, alkynes, cycloalkanes or cycloalkene

In this work, structure H hydrate phase equilibrium of hydrogen in the presence of organic promoter is predicted using a proposed thermodynamic model. The investigated promoters are various n-alkanes, n-alkenes/alkynes, and cycloalkanes/cycloalkene. The van der Waals–Platteeuw solid solution theory is used for determination of the fugacity of water in hydrate phase. Phase behavior of the hydrogen + water system is modeled using the Valerama–Patel–Teja equation of state (VPT-EoS) with non-density dependent mixing rules. Due to the lack of experimental solubility data of hydrogen in the investigated promoters, the phase equilibria of the hydrogen + promoter system is treated using the VPT-EoS-GE method consisting the UNIFAC activity model and the modified Huron–Vidal (MHV1) mixing rules. The obtained results show reasonable agreement of the predictions with the existing experimental data from the literature. Finally, the hydrogen storage capacity of the corresponding clathrate hydrates is predicted as well as the occupancies of the clathrate hydrate cavities.

► Phase equilibria of hydrogen structure H hydrate are predicted.
► The investigated promoters include n-alkanes, n-alkenes/alkynes, and cycloalkanes/cycloalkene.
► The vdW–P theory and the VPT-EoS are applied for modeling.
► Acceptable agreement is found between the available data and the predicted results.