Construction of an Anion-Pillared MOF Database and the Screening of MOFs Suitable for Xe/Kr Separation

Abstract

The separation of xenon/krypton (Xe/Kr) mixtures is a challenging process. Many porous materials allow the adsorption of both Xe and Kr but only with low selectivity. Anion-pillared metal–organic frameworks (MOFs), featuring the anion groups as structural pillars, show potential in gas separations, but only a limited number of them have been synthesized. Here, we describe a collection of 936 anion-pillared MOFs based on 22 experimentally available structures. We performed density functional theory (DFT) optimization and then assigned density-derived electrostatic and chemical (DDEC) charges for each MOF to make them well suited to molecular simulations. The structural properties of the MOFs vary more strongly with the choice of the organic ligand than with other aspects like fluorine groups and metal centers. We then screened the entire collection of MOFs in the context of Xe/Kr separation at room temperature. Compared with previously reported MOFs, the interpenetrated MOF SIFSIX-6-Cd-i is predicted to perform better for Xe/Kr separations, with a good balance between working capacity (1.62 mmol/g) and separation selectivity (16.4) at 298 K and 100 kPa. We also found that the heterogeneity of fluorine groups within a MOF can help to enhance Xe working capacity without reducing the Xe/Kr selectivity, suggesting that synthesis of anion-pillared MOFs with mixed fluorine groups may lead to improved Xe/Kr separation performance.

MOFs-Derived Zn-Based Catalysts in Acetylene Acetoxylation

“…MOFs are crystalline nanoporous materials with a framework structure composed of transition metal ions and organic ligands [ 18 ], with the metal components dispersed one by one through organic ligands. On account of the large specific surface area, abundant pore structure, and surface defects of MOFs, MOFs have become a research hotspot in the fields of gas storage, gas adsorption, separation, sensors, drug controllable release, and catalytic reactions [ 19 , 20 , 21 , 22 , 23 , 24 , 25 ]. Because of their excellent chemical and thermal stability, MOFs are also used as a template or precursor for the preparation of porous carbon materials or metal composite materials [ 26 ].…”

Multi-Level Computational Screening of in Silico Designed MOFs for Efficient SO2 Capture

“…The structures of MFM-300(In) and SIFSIX-1-Cu were obtained from the literature. 28 , 76 MFM-300(In) and SIFSIX-1-Cu were reported to have high SO 2 /CH 4 (425 and 1241.4), SO 2 /CO 2 (60 and 70.7), and SO 2 /N 2 (5000 and 3145.7) selectivities calculated using IAST for binary mixtures involving 50 and 10% SO 2 under ambient conditions, respectively. 26 , 28 For all three gas separations, MFM-300(In) demonstrates highly SO 2 selective behavior (SO 2 /CH 4 , SO 2 /CO 2 , and SO 2 /N 2 selectivities of 3128.5, 181.1, and 24,937.1, respectively); however, its SO 2 working capacity (0.6, 0.4, and 0.6 mol/kg, respectively) and regenerability (7.5, 6.1, and 8.2%, respectively) are low.…”

High-Throughput Screening of Anion-Pillared Metal–Organic Frameworks for the Separation of Light Hydrocarbons

“…16−18 In recent work, we have constructed a database of 936 anion-pillared MOFs based on 22 experimentally available structures. 19 Here, we carry out high-throughput screening based on the anion-pillared MOF database for the separations of C We used working capacity and selectivity in the Henry's limit at ambient temperature as metrics for the initial screening. The working capacities were evaluated by a rapid prediction method based on Langmuir isotherms of pure hydrocarbons.…”