Evaluation of an industrial pilot scale densified MOF-177 adsorbent as an on-board hydrogen storage medium

Abstract

Exploring and evaluating on-board solid state hydrogen storage systems performance are of great interest for fuel cell electric vehicles development. In this report, we present gravimetric and volumetric capacities of a hydrogen storage system based on a densified MOF-177 adsorbent. This is, to our knowledge, the first thorough study of an engineered industrial scale MOFs for hydrogen storage application. The measurements were performed over the 50–120 K and 0–40 bar ranges, and modeled using micropore filling approaches. The performances of a potential 100 L vessel filled with the densified MOF-177 are inferred from the modeling parameters. A comparison of this technology with the 70 MPa compressed gas hydrogen system shows under which conditions the adsorbent offer advantages in terms of volumetric and gravimetric capacities. Further comparison with AX-21 activated carbon pellets reveals that densified MOF-177 stores about 40% more at 77 K and 35 bar. In order to get a physically sound modeling analysis, we introduced an approach to establish effective saturation pressures for supercritical adsorption. This approach insures a consistency between key model parameters and the observed liquid properties of the adsorbed phase at the lowest temperatures. We show that modeling using temperature-dependent saturation pressures and adsorbed phase densities leads to important differences in the projected usable storage capacities. Such differences can be as much as 25% at 50 K in the high pressure limit, revealing the importance of physical insights in the modeling approach.