Theoretical Hydrogen Cryostorage\nin Doped MIL-101(Cr) Metal–Organic Frameworks

Abstract

The cryoadsorption (77 K) of H₂ in the MIL-101­(Cr)\n[MIL:\nMaterials from the Institute Lavoisier] metal–organic framework (MOF)\nmaterial and its Li⁺, Mg²⁺, Mn²⁺,\nand Co²⁺-doped analogues was explored by grand canonical\nMonte Carlo simulations (GCMC). The optimal hydrogen uptake in this\n highly\n porous material is\nstill experimentally unknown considering the experimental difficulty\nto fully activate this sample. Indeed, a H₂ adsorption isotherm has only been measured for a mildly activated version (MIL-101b­(Cr)). Moreover, the recent adsorption\nof CO₂ in better activated form (MIL-101c­(Cr))\nshows an increase up to 30% of the saturation capacity in comparison to MIL-101b­(Cr). From GCMC simulations, we provide the optimal uptake and delivery of H₂ at 77 K in the MIL-101(Cr) and its doped analogues at 77 K. For\nthe Li-doped material we predict a hydrogen uptake of 10 wt % and\na delivery of 6 wt %, which achieve the mass storage and delivery\ndensity target established by the U.S. Department of Energy for 2015.