Ab initio mechanistic insights into the stability, diffusion and storage capacity of sI clathrate hydrate containing hydrogen
Résumé
Gas hydrates are non-conventional materials offering great potential in capturing, storage, and sequestration of different gases. The weak van der Waals interactions between a gas molecule and the pore walls stabilize these non-stoichiometric structures. The present article reports an ab initio improved van der Waals density functional (vdW-DF2) study devoted to the interactions associated with H2, CH4, and CO2 adsorption in sI clathrate hydrate. The study provides the clathrate stability, diffusion, and energy storage of possible mixed gas occupancy in sI cages in the presence of H2. The results also provided the hydrogen energy landscapes and the estimated diffusion activation energy barriers to the large and small cage to be 0.181 and 0.685 eV, respectively. In addition, the results showed that the presence of CH4 or CO2 could enhance the storage capacity, thermodynamic stability, and hydrogen diffusion in sI clathrates. The volumetric storage, gravimetric storage, and molecular hydrogen content in H2–CH4 binary sI clathrate are calculated to be 2.0 kW h/kg, and 1.8 kW h/L, and 5.0 wt%, respectively. These results are comparable to DOE targets of hydrogen storage.
Domaines
Chimie théorique et/ou physiqueOrigine | Fichiers produits par l'(les) auteur(s) |
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