Discovery of High‐Performing Metal–Organic Frameworks for On‐Board Methane Storage and Delivery via LNG–ANG Coupling: High‐Throughput Screening, Machine Learning, and Experimental Validation

Abstract

Liquefied natural gas (LNG) gasification coupled with adsorbed natural gas (ANG) charging (LNG-ANG coupling) is an emerging strategy for efficient delivery of natural gas. However, the potential of LNG-ANG to attain the advanced research projects agency-energy (ARPA-E) target for onboard methane storage has not been fully investigated. In this work, large-scale computational screening is performed for 5446 metal-organic frameworks (MOFs), and over 193 MOFs whose methane working capacities exceed the target (315 cm 3 (STP) cm −3 ) are identified. Furthermore, structure-performance relationships are realized under the LNG-ANG condition using a machine learning method. Additional molecular dynamics simulations are conducted to investigate the effects of the structural changes during temperature and pressure swings, further narrowing down the materials, and two synthetic targets are identified. The synthesized DUT-23(Cu) and DUT-23(Co) show higher working capacities (≈373 cm 3 (STP) cm −3 ) than that of any other porous material under ANG or LNG-ANG conditions, and excellent stability during cyclic LNG-ANG operation.

Porosity Engineering of Hyper-Cross-Linked Polymers Based on Fine-Tuned Rigidity in Building Blocks and High-Pressure Methane Storage Applications

“…The key for the ANG system is seeking adsorbents with high-capacity methane storage while addressing ambitious targets updated by the Advanced Research Projects Agency-Energy (ARPA-E) of the U.S. Department of Energy (DOE), i.e., a gravimetric storage capacity of 0.5 g g –1 and a volumetric storage capacity of 263 cm 3 (standard temperature and pressure, STP) cm –3 . Numerous successful efforts have been developed to approach the ultimate target by designing novel porous adsorbents with ultrahigh porosity (especially the specific surface area and considerable pore volume) or pressure-triggered flexible frameworks with gate-opening behavior. − …”

A Self-Evolutionary Methodology for Reverse Design of Novel MOFs

“…The LJ potential parameters for the CH 4 molecule were taken from the TraPPE force field, along with those for the MOF atoms adopted from the UFF force field . This set of force fields has been widely employed in molecular simulation studies of CH 4 adsorption in a diversity of nanoporous materials. , A cutoff distance of 14.0 Å was used for all of the LJ interactions. The Lorentz–Berthelot mixing rules were used to calculate the LJ-crossed parameters between different atoms.…”

“…54 This set of force fields has been widely employed in molecular simulation studies of CH 4 adsorption in a diversity of nanoporous materials. 55,56 A cutoff distance of 14.0 Å was used for all of the LJ interactions. The Lorentz−Berthelot mixing rules were used to calculate the LJ-crossed parameters between different atoms.…”

Promotion of methane storage capacity with metal–organic frameworks of high porosity

“…Ultrahigh porosity and surface areas have been realized in MOFs, making them outstanding candidates for gas storage applications. Further, their well-defined structures have enabled a deeper understanding of structure-property relationships through computational approaches [19][20][21][22] as well as empirical analysis of pore features 23 to screen or predict high performance materials. Our previous studies have established empirical equations based on the pore volume of MOFs and pore occupancy (total adsorption divided by saturated adsorption) to predict methane adsorption capacity at 35 bar and 65 bar with reasonable accuracy.…”