Metal

Catalysis

Adsorption

Krypton

Density functional theory

Bar (unit)

Porosity

Physical chemistry

Physics

Organic chemistry

Astronomy

Polar

Metal-organic framework

Computational chemistry

Analytical Chemistry (journal)

Chemistry

Selectivity

Meteorology

Xenon

Journal of the American Chemical Society

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 cm3/cm3 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.

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