Modeling High-Pressure Hydrogen Uptake by Nanoporous Metal–Organic Frameworks: Implications for Hydrogen Storage and Delivery

Abstract

Due to their very high porosity and superior textural properties, metal–organic frameworks (MOFs) are promising nanoporous materials for hydrogen storage by cryocompression. Herein, we investigated hydrogen adsorption on four commercial MOFs, namely, MIL53-Al, MOF-5, HKUST-1, and MOF-177, over a temperature range of 77 to 273 K and pressures up to 14 MPa. The modified Dubinin–Astakhov equation was used to fit the experimental adsorption data, and six parameters (m, nmax, α, β, P0, and Va) were obtained. We concluded that the parameters nmax and Va are related to the micropore volume, while α, β, m, and P0 are related to the average micropore size. Compared to hydrogen compression in an empty tank, the introduction of MOF-5 enhanced the volumetric hydrogen storage at 77 K and 10 MPa from 31 to 42 kg m–3. The released H2 capacities of MOFs from a loading pressure of 10 MPa to a discharge pressure of 0.5 MPa were determined for either isothermal discharge at 77 K or after temperature increase to 160 K. For MOF-5, the amount of usable hydrogen increased up to 10.6 wt % (40.8 mg cm–3) by pressure drop (from 10 to 0.5 MPa) and temperature increase (from 77 to 160 K).