Evaluating the High-Pressure Volumetric CH4, H-2, and CO2 Storage Properties of Denser-Version Isostructural soc-Metal-Organic Frameworks

The MOF platform based on soc topology showed recent developments for gas storage applications. soc-MOFs with very open structures, such as Al-soc-MOF-1, exhibited promising gravimetric storage performance but with compromised volumetric capacities. However, the volumetric capacity is a critical parameter to consider for vehicles such as trucks. The practical constraints under such circumstances are mainly linked to the tank volume required to accommodate adsorbents. In this work, the gas storage performances of dense soc-MOFs assembled from different metal precursors and 3,3 & PRIME;,5,5 & PRIME;-azobenzene tetracarboxylic acid, denoted as In-soc-MOF-1a, In-soc-MOF-1b, In-soc-MOF-1c, Ga-soc-MOF-1a, Fe-soc-MOF-1a, Fe-soc-MOF-1b, and Al-soc-MOF-1d, with 1a, 1b, 1c, and 1d representing NO3-, Cl-, Br-, and HO- counterions, respectively, were evaluated. Using the crystallographic densities of each MOF, volumetric uptakes were calculated from gravimetric values. The volumetric CH4, H-2, and CO2 uptakes of the soc-MOFs showed a gain in storage capacity upon using denser versions, with a higher CH4 uptake of Fe-soc-MOF-1b (128 g L-1 at 50 bar) than the extended analogs (& SIM;120 g L-1 for Fe-PBPTA-soc-MOF). The counteranions were also observed to have an impact on the volumetric capacities, with In-soc-MOF-1c > In-soc-MOF-1b > In-soc-MOF-1a for CH4 and the reverse order for H-2 capacities. The performances are also comparable to those of most of the previously reported benchmark MOFs.