Figure 1. Computational screening of MOFs for Xe/Kr separations at dilute conditions relevant to UNF reprocessing off-gas.

We computed the Henry coefficients of Xe and Kr in ∼125,000 MOF structures; the selectivity at dilute conditions is the ratio of Henry coefficients. (a) Distribution of simulated selectivities for experimentally synthesized (green) and hypothetical (yellow) MOF structures; vertical, dashed line is SBMOF-1 (KAXQIL in the Cambridge Structural Database (CSD)). (b) Histogram showing relationship between selectivity and pore size, with the largest included sphere diameter as a metric; colour shows average energy of Xe adsorption in that bin. SBMOF-1 (KAXQIL in CSD), with simulated selectivity 70.6 and largest included sphere diameter of 5.1 Å, is indicated. Vertical, dashed line is the distance that yields the minimum energy in a Xe–Xe Lennard–Jones potential. (c) SBMOF-1 is composed of corner sharing, octahedrally coordinated calcium chains along the crystallographic b direction, which are connected by organic linkers, forming a one-dimensional nanoporous channel. (d) Side view. Shown are the calculated potential energy contours of a Xe atom adsorbed in the pore (blue surface, −32 kJ mol⁻¹; white surface, 15 kJ mol⁻¹).