Selective Xenon Recovery Using Aluminum-Based Metal–Organic Frameworks with Conserved Pore Topology

Xenon (Xe) is a commercially valuable element found in trace amounts in the off-gas from used nuclear fuel. Recovering Xe from these streams provides a cost-effective means to increase its supply. However, achieving high-purity Xe recovery is challenging due to the need for separation from nearly identical krypton (Kr). Metal-organic frameworks (MOFs), a class of crystalline porous materials, show potential to separate Xe and Kr by utilizing differences in their kinetic diameters, allowing for selective separation. In this work, we study the impact of pore aperture and volume on selective Xe recovery using four robust aluminum MOFs: Al-PMOF, Al-PyrMOF, Al-BMOF and MIL-120, all with conserved structural topology. The pore topology in each MOF is dictated by the dimensions of the tetracarboxylate ligand employed, with larger ligands leading to MOFs with increased pore size and volume. Our experimental and computational investigations revealed that MIL-120 exhibits the highest affinity (21.94