In order to accurately estimate the thermodynamic properties of hydrogen clathrate hydrates, we developed a method based on the solid solution theory of van der Waals and Platteeuw. This model allows one to take into account the influence of guest molecules on the host lattice and guest-guest interactions—especially when more than one guest molecule occupies a cage. The free energies, equations of state, and chemical potentials of hydrogen and mixed propane-hydrogen clathrate hydrates of cubic structure II with different cage fillings have been estimated using this approach. Moreover, the proposed theory has been used for construction $p-T$ phase diagrams of hydrogen hydrate and mixed hydrogen-propane hydrates in a wide range of pressures and temperatures. For the systems with well defined interactions the calculated curves of “guest gas-hydrate-ice ${\text{I}}_h$ ” equilibrium agree with the available experimental data. We also believe that the present model allows one not only to calculate the hydrogen storage ability of known hydrogen hydrate but also predict this value for structures that have not yet been realized by experiment.

In this contribution, a method based on a solid solution theory of clathrate hydrate for multiple cage occupancy, host lattice relaxation, and guest-guest interactions is presented to estimate hydrate formation conditions of binary and ternary gas mixtures. We performed molecular modeling of the structure, guest distribution, and hydrate formation conditions for the CO₂ + CH₄ and CO₂ + CH₄ + N₂ gas hydrates. In all considered systems with and without N₂, at high and medium content of CO₂ in the gas phase, we found that CO₂ was more favorable in occupying clathrate hydrate cavities than CH₄ or N₂. The addition of N₂ to the gas phase increased the ratio concentration of CO₂ in comparison with the concentration of CH₄ in clathrate hydrates and made gas replacement more effective. The mole fraction of CO₂ in the CO₂ + CH₄ + N₂ gas hydrate rapidly increased with the growth of its content in the gas phase, and the formation pressure of the CO₂ + CH₄ + N₂ gas hydrate rose in comparison to the formation pressure of the CO₂ + CH₄ gas hydrate. The obtained results agreed with the known experimental data for simple CH₄ and CO₂ gas hydrates and the mixed CO₂ + CH₄ gas hydrate.

Ozone storage capacity in O₃+ O₂+ N₂+ CO₂clathrate hydrate was estimated theoretically.

Two new isostructural microporous coordination frameworks [Mn₃(Hpdc)₂(pdc)₂] (1) and [Mg₃(Hpdc)₂(pdc)₂] (2) (pdc^2– = pyridine-2,4-dicarboxylate) showing primitive cubic (pcu) topology have been prepared and characterized. The pore aperture of the channels is too narrow for the efficient adsorption of N₂; however, both compounds demonstrate substantially higher uptake of CO₂ (119.9 mL·g^–1 for 1 and 102.5 mL·g^–1 for 2 at 195 K, 1 bar). Despite of their structural similarities, 2 shows a typical reversible type I isotherm for adsorption/desorption of CO₂, while 1 features a two-step adsorption process with a very broad hysteresis between the adsorption and desorption curves. This behavior can be explained by a combination of density functional theory calculations, sorption, and X-ray diffraction analysis and gives insights into the further development of new sorbents showing adsorption/desorption hysteresis.