Densified HKUST-1 Monoliths as a Route to High Volumetric and Gravimetric Hydrogen Storage Capacity

Abstract

We are currently witnessing the dawn of hydrogen (H 2 ) economy, where H 2 will soon become a primary fuel for heating, transportation, and longdistance and long-term energy storage. Among diverse possibilities, H 2 can be stored as a pressurized gas, a cryogenic liquid, or a solid fuel via adsorption onto porous materials. Metal−organic frameworks (MOFs) have emerged as adsorbent materials with the highest theoretical H 2 storage densities on both a volumetric and gravimetric basis. However, a critical bottleneck for the use of H 2 as a transportation fuel has been the lack of densification methods capable of shaping MOFs into practical formulations while maintaining their adsorptive performance. Here, we report a high-throughput screening and deep analysis of a database of MOFs to find optimal materials, followed by the synthesis, characterization, and performance evaluation of an optimal monolithic MOF ( mono MOF) for H 2 storage. After densification, this mono MOF stores 46 g L −1 H 2 at 50 bar and 77 K and delivers 41 and 42 g L −1 H 2 at operating pressures of 25 and 50 bar, respectively, when deployed in a combined temperature− pressure (25−50 bar/77 K → 5 bar/160 K) swing gas delivery system. This performance represents up to an 80% reduction in the operating pressure requirements for delivering H 2 gas when compared with benchmark materials and an 83% reduction compared to compressed H 2 gas. Our findings represent a substantial step forward in the application of high-density materials for volumetric H 2 storage applications.

Recent advances of stimuli-responsive viologen-based nanocomposites

“…The investigation of MOFs is related to coordination chemistry, organic chemistry, inorganic chemistry, synthetic chemistry, etc., and displays extensive application prospects in detection, [43][44][45] adsorption and separation, [46][47][48] luminescence, 49-51 magnetism, 52,53 catalysis, 54,55 and energy storage. [56][57][58] Recently, bipyridine ligands that grafted substituents of nitrogenous oxygen ligands onto the bipyridine skeleton are successfully synthesized. Due to the excellent coordination ability of nitrogen and oxygen atoms, the modified bipyridine ligands are easily coordinated with metal ions or ion clusters.…”

Hydroxide ion-conducting metal–organic frameworks for anion-exchange membrane applications

“…Recent advances in developing processing and fabrication technologies, such as monolith, thin film, or fibre-mat production give confidence that such challenges regarding the processing of MOFs are easily amenable to membrane formation with controlled porosity and thickness will be overcome. [56][57][58][59][60][61][62][63][64] It should be noted that with the advent of industrial production of certain MOFs, it has been shown that their production costs can be reduced significantly, as highlighted by recent reports. 65,66 However, to date there is only a handful of commercially available MOFs and their price is currently not competitive with well-established productions such as ceramics or common polymers.…”

“…Considering that recent advances in (i) approaches for improving MOF stability in alkaline environments; 86 (ii) shaping and forming MOFs for more suitable mechanical characteristics [56][57][58][59][60][61][62][63][64] and new ways of improving static robustness; 93 (iii) more sustainable approaches to production; [67][68][69][70] and (iv) lowered costs 65,94 -all of which have been explored in excellent recent review papers. We identify the hydroxide-ion conductivity as the principal remaining bottleneck and therefore our continued discussion will be focussed on that.…”

Multivariate Flexible Framework with High Usable Hydrogen Capacity in a Reduced Pressure Swing Process

“…Therefore, for a 45-bar pressure swing process only going up to 50 bar at 77 K, i.e., (5−50−5), an 84% usable capacity of 1.17 mass % is enabled (0.23−1.4−0.23 mass %, Figure S23). For comparison, the recently reported benchmark monolithic HKUST-1 with an impressively high absolute total capacity of 4.2 mass % has a usable capacity of about ≈24% for a similar (5−50−5) bar or even an increased (5−100−5) bar pressure swing at 77 K. 30 Therefore, only ≈0.8 mass % is usable in this pressure swing process with monolithic HKUST-1 owing to the Type I adsorption−desorption profile.…”