A Robust Squarate-Based Metal–Organic Framework Demonstrates Record-High Affinity and Selectivity for Xenon over Krypton

Abstract

The efficient separation of xenon (Xe) and krypton (Kr) is one of the industrially important processes. While adsorptive separation of these two species is considered to be an energy efficient process, developing highly selective adsorbent remains challenging. Herein, a rigid squarate-based metal− organic framework (MOF), having a perfect pore size (4.1 Å × 4.3 Å) comparable with the kinetic diameter of Xe (4.047 Å) as well as pore surface decorated with very polar hydroxyl groups, is able to effectively discriminate Xe atoms, affording a record-high Xe/Kr selectivity. An exceptionally high Xe uptake capacity of 58.4 cm 3 /cm 3 and selectivity of 60.6 at low pressure (0.2 bar) are achieved at ambient temperature. The MOF exhibits the highest Xe Henry coefficient (192.1 mmol/g/bar) and Xe/Kr Henry selectivity (54.1) among all state-of-the-art adsorbents reported so far. Direct breakthrough experiments further confirm the excellent separation performance. The density functional theory calculations reveal that the strong interaction between Xe and the framework is a result of the synergy between optimal pore size and polar porosity.

Simultaneous interlayer and intralayer space control in two-dimensional metal−organic frameworks for acetylene/ethylene separation

“…Owing to their inherent diversity, these materials enable precise control of pore shape, pore chemistry and pore size, thereby providing a versatile platform for separation processes [8][9][10][11][12][13][14][15] . In terms of trace gas removal, numerous studies have focused on the rational design of three-dimensional (3D) MOFs with uniform sub-nanometer pores [16][17][18][19][20][21][22][23][24][25] . Despite significant achievements, designing new materials that outperform existing benchmark adsorbents remains a formidable challenge.…”

CoNi Alloy Nanoparticles Embedded in Metal–Organic Framework‐Derived Carbon for the Highly Efficient Separation of Xenon and Krypton via a Charge‐Transfer Effect

“…As presented in the Supporting Information, Figure S7b and Table S3, the Q st at zero coverage for Xe of Ni@C‐700 and NiCo@C‐700 are estimated to be 25.80 kJ mol −1 and 25.70 kJ mol −1 , respectively. They are significantly lower than that of most best‐performing MOFs, such as Co 3 (C 4 O 4 ) 2 (OH) 2 (43.6 kJ mol −1 ), [5a] CROFOUR‐1‐Ni (37.4 kJ mol −1 ) [5e] and SB‐MOF‐1 (35 kJ mol −1 ), [5i] demonstrating the easier regeneration of such carbon adsorbents. Both of them are dramatically higher than those of Kr, N 2 , O 2 and Ar.…”

“…The Langmuir fitting parameters and Henry's selectivity of adsorbents are displayed in Table S2. It is worth noting that NiCo@C‐700 exhibits an extremely high Henry's selectivity of Xe/Kr (20.5) at low concentration, outperforming most reported porous adsorbents, just lower than CROFOUR‐1‐Ni (22) [5e] and Co 3 (C 4 O 4 ) 2 (OH) 2 (69.7) [5a] . The high Henry's selectivity of Xe/Kr demonstrate its excellent capacity for Xe capture at dilute conditions.…”

Modulation of Disordered Coordination Degree Based on Surface Defective Metal–Organic Framework Derivatives toward Boosting Oxygen Evolution Electrocatalysis

“…The structure of [Co 3 (C 4 O 4 ) 2 (OH) 2 ]⋅3H 2 O was delineated in Figure a. [ 20 ] There were two different Co atoms with trans ‐OH and cis ‐OH. These formed distorted octahedral coordination and shared the edges and vertices to form interlinked [Co 3 (OH) 2 ] 4+ brucite‐like ribbons.…”