Efficient Capture and Separation of Xenon/Krypton from Off-Gas by a Radiation-Resistant Metal-Organic Framework.

The capture of xenon (Xe) and krypton (Kr) from the off-gas of used nuclear fuel is of great importance to the treatment of radioactive wastes and production of high purity Xe. Solid sorbents, in particular metal-organic frameworks (MOFs), show promise in gas capture. However, the unknown radiation resistance of MOFs has limited their development. Herein, the efficient capture and separation of Xe/Kr by MFM-520, which strikes a remarkable stability toward 1750 kilogray (kGy) γ-irradiation, is reported. Under ambient conditions, dynamic breakthrough experiments confirm the efficient separation performance, yielding a Xe capacity of 66 and 0.2 mg g-1 from a by-product of air separation (Xe/Kr: 20/80; v/v) and off-gas (Xe/Kr: 400/40 ppm balance in air), respectively. In situ synchrotron X-ray single crystal diffraction and solid-state nuclear magnetic resonance (ssNMR) studies reveal that the optimal micropore of MFM-520 underpins specific host-guest interactions to Xe, resulting in selective Xe capture.