Recovery of Acid-Gas-Degraded Zeolitic Imidazolate Frameworks by Solvent-Assisted Crystal Redemption (SACRed).

The acid stability of zeolitic imidazolate frameworks (ZIFs) is an important issue hindering their application. Acid-gas damage of ZIFs has been considered irreversible. However, we demonstrate a methodology called solvent-assisted crystal redemption (SACRed) to reverse acid-gas damage to ZIFs with a high degree of structural and functional recovery. For example, post-SACRed ZIF-8 is shown to be structurally and chemically near-identical with the original pristine ZIF-8 that suffered a large loss of surface area, porosity, and crystallinity during acid-gas exposure. We also provide mechanistic insight into the recovery process using deuterium-labeled linkers and 2H NMR spectroscopy. SACRed treatments could allow large extensions in the lifetime of ZIF-based membranes and adsorbents that degrade over time.