A Simulation Study of Hydrogen in Metal-Organic Frameworks

Molecular simulations have been used to evaluate the effect exerted by metal centres on the adsorption and diffusion of hydrogen in metal organic frameworks. Simulations were carried out for the MIL-53 (Cr and Al) structures and the isostructural vanadium analogue MIL-47 at room temperature. To validate the models and force fields used in this work, the adsorption isotherms, energies and entropies, and self-diffusivities in Cu-BTC and IRMOF-1 metal-organic frameworks were computed. Using the validated force fields and models, a detailed analysis of the preferential adsorption sites is reported, allowing the energetic contribution in the low-coverage regime (Henry constants and adsorption energies and entropies) to be determined as a function of loading (adsorption isotherms). The influence of each energetic contribution to the charged and uncharged models of hydrogen has also been analyzed.