Evaluation of hydrogen storage ability of hydroquinone clathrates using molecular simulations

Abstract

• Maximum occupancy of the hydroquinone clathrate by hydrogen guest molecules. • Dynamics of the filling process of an empty by molecular dynamics simulations. • Slow diffusion of the guests and formation of a high-density adsorbed hydrogen layer. • Occupancy by hybrid GCMC/MD simulations matches closely experimental results. Hydroquinone clathrates have been proposed as potential gas separation and storage media. Experimental results have demonstrated enhanced preferential adsorption for certain guest molecules, and also stability over temperature and pressure ranges that make them promising candidates to be employed in applications as hydrogen storage. Despite this, the characterization of these inclusion solids from thermodynamic and kinetic perspectives is still poor. In this work, we have tried to estimate the hydrogen storage ability of these clathrates using molecular simulations. The process of diffusion of hydrogen guest molecules from an external reservoir has been simulated using molecular dynamics, and the thermodynamic occupancy limit at different ( T , p ) conditions has been computed using hydrid Grand-Canonical Monte Carlo/Molecular Dynamics. The results show that hydrogen diffusion from an external reservoir is limited by interfacial phenomena in the clathrate surface, and also that multiple guest occupancy and its distribution can be computed using the described approach.