Evaluation of the Hydrogen-Storage Capacity of Pure H2 and Binary H2-THF Hydrates with Monte Carlo Simulations

Grand Canonical Monte Carlo simulations are employed to investigate the hydrogen-storage capacity of pure H2 and binary H2-THF hydrates (both of them are of sII type) at various temperatures, pressures, and THF concentrations. It is found that the storage capacity of pure H2 hydrate could reach 3.0 wt % only at pressures above 380 MPa (at 274 K). Depending on the pressure, the large cavities of this hydrate can accommodate up to four H2 molecules, whereas the small ones are singly occupied even at pressures as high as 450 MPa. For the binary H2-THF hydrate, all large cavities are found to be occupied by a single THF molecule, independent of the THF concentration in the initial solution in a wide range of conditions, with no hydrogen molecules entering the large cavities. Likewise, in the pure H2 hydrate, small cavities are found to be singly occupied over the entire pressure range considered (1−350 MPa). The H2 storage capacity of the binary H2-THF hydrate, at temperatures close to ambient, is estimated t...