High Performance Hydrogen Storage from Be-BTB Metal–Organic Framework at Room Temperature

Abstract

The metal-organic framework beryllium benzene tribenzoate (Be-BTB) has recently been reported to have one of the highest gravimetric hydrogen uptakes at room temperature. Storage at room temperature is one of the key requirements for the practical viability of hydrogen-powered vehicles. Be-BTB has an exceptional 298 K storage capacity of 2.3 wt % hydrogen. This result is surprising given that the low adsorption enthalpy of 5.5 kJ mol(-1). In this work, a combination of atomistic simulation and continuum modeling reveals that the beryllium rings contribute strongly to the hydrogen interaction with the framework. These simulations are extended with a thermodynamic energy optimization (TEO) model to compare the performance of Be-BTB to a compressed H2 tank and benchmark materials MOF-5 and MOF-177 in a MOF-based fuel cell. Our investigation shows that none of the MOF-filled tanks satisfy the United States Department of Energy (DOE) storage targets within the required operating temperatures and pressures. However, the Be-BTB tank delivers the most energy per volume and mass compared to the other material-based storage tanks. The pore size and the framework mass are shown to be contributing factors responsible for the superior room temperature hydrogen adsorption of Be-BTB.

Analytical Representations of Regular-Shaped Nanostructures for Gas Storage Applications

“…Although computational simulations are currently the preferred methods to explore the properties of porous materials due to their capacity to be highly accurate, analytical models are less time-consuming, and do not require considerable computing power. In addition, applied mathematical modelling has been shown to produce results that are comparable with computer simulations and existing experimental data [7,13].…”

“…The modelling output for total hydrogen uptake provided good agreement with various experimental and simulation results in the literature which ensures the accuracy of the predictions made. A similar analytical method is also employed by Lim et al [7] to explore the hydrogen adsorption on beryllium benzene tribenzoate (Be-BTB). The hydrogen adsorption isotherm calculated using their proposed analytical model closely matches the data obtained from experiments and simulations at 77 and 298 K. Using that model, the authors reached the same conclusions as the results obtained in the literature, that is, there is a correlation between hydrogen uptake and both surface area and pore volume at high pressure.…”

Mathematical modeling of interaction energies between nanoscale objects: A review of nanotechnology applications

“…In this section, the approach adopted by Thornton and colleaugues [80][81][82] and Lim et al 87 is summarized using idealized building blocks to represent the interactions of both simple and more complicated geometries of nanostructures yielding simple and elegant analytical models. First, the analytical representations of the van der Waals interaction between an atom and the building blocks, which are represented by standard geometrical shapes such as points, lines, planes, rings, spheres, and cylinders are determined.…”

“…81 Moreover, the same approach has also been proved as a useful technique to investigate the effect of pore size in MOFs. [80][81][82]86,87 Furthermore, Chan and Hill 84 investigate the storage of hydrogen molecules inside graphene-oxide frameworks comprising two parallel graphenes rigidly separated by perpendicular ligands. These authors find 6.33 wt% for GOF-28 at a temperature of 77 K and a pressure of 1 bar which is consistent with several experimental and other computational results.…”

“…[47][48][49] Moreover, this method has also been used in systems involving proteins and enzymes, [50][51][52] DNA, [52][53][54][55] lipid bilayer and lipid nanotube, [56][57][58] water molecule, [59][60][61][62][63][64] benzene, 2,65-69 methane, 2,3,70-75 ions, [75][76][77][78][79] and gas storage and porous aromatic frameworks. [80][81][82][83][84][85][86][87][88] The Lennard-Jones potential function F(r) which accounts for the interaction of two non-bonded atoms can be written in the following form…”