An Ultrastable Hydrogen-Bonded Organic Framework With Two-Dimensional Pores for Rapid Adsorption Kinetics and...

Developing hydrogen-bonded organic frameworks (HOFs) for highly efficient Xe/Kr separation is an attractive alternative for producing high-purity noble gases. However, its practical application is hampered by insufficient binding sites and intrinsically slow adsorption kinetics. We herein report a microporous HOF (HOF-TBPDM) featuring the unique two-dimensional (2D) and size-matched pore architecture, which enables the rapid diffusion of Xe and high-efficiency Xe/Kr separation. Specifically, HOF-TBPDM achieves a high Xe uptake and a record Xe/Kr IAST selectivity (26.9) at 298 K and 1 bar. Especially, the kinetic adsorption results confirm the 2D pores lead to the rapid Xe diffusion rate. Dynamic breakthrough experiments indicate that after one cycle of separation operation 4.8 mol kg^-1 high-purity Kr (>99.99%) and 1.0 mol kg^-1 Xe (>99.9%) can be directly obtained. The dynamic selectivity calculated from desorption process is as high as 16.5, which exceeds all the reported porous organic materials. Gas-loaded crystal data combined with molecular modeling clearly reveal that the size-matched pores within HOF-TBPDM induce a stronger polarization effect on Xe than Kr, leading to preferential binding of Xe molecules. Overall, this study demonstrates the effectiveness of 2D pore in HOFs for balancing thermodynamic adsorption and kinetic diffusion, providing a viable strategy for advanced Xe/Kr separation.