Nicole L. Kelly, Maximillian G. Stanzione, Deborah Brako-Amoafo, Gaynor B. Lawrence, Cameron M. Rice, Paul Wheatley, Jonathan M. Keys, Christopher J. Heard, Henry E. Fischer, Alexandra S. Gibbs, Sharon E. Ashbrook, Russell E. Morris
High Resolution Image Download MS PowerPoint Slide Four different hydrophobic, low-defect pure-silica zeolites are contacted with isotopically enriched water at room temperature, and all show isotope exchange of 17 O into the Si–O–Si units of the zeolite structure using multiple-quantum MAS NMR spectroscopy. For the CHA zeolite structure, exchange of 18 O into the framework was identified using neutron diffraction─the first time this technique has been used to differentiate oxygen isotopes in any solid-state material. The results indicate that even supposedly very hydrophobic pure-silica zeolites are susceptible to oxygen exchange under very mild aqueous conditions. This has important consequences for our view of the structure of zeolites in contact with water.