A comparison of hydrogen storage in activated carbons and a metal–organic framework (MOF-5)

A hydrogen storage study, on gravimetric and volumetric bases, has been carried out on three adsorbents having similar adsorption capacities: two activated carbons and a metal organic framework (MOF-5). These three samples have similar hydrogen storage on a gravimetric basis. However, expressed on a volumetric basis, both AC have higher hydrogen storage than MOF-5. Wrong conclusions could be avoided, when comparing these two types of adsorbents, if their hydrogen storage data were reported on a volumetric basis, using reliable measurable densities. Tap or packing densities are the most suitable. Crystal density, mostly used for reporting hydrogen storage on MOF, gives unrealistically high volumetric storage values.