Local probes show that framework modification in zeolites occurs on ammonium exchange without calcination

摘要: Framework modification involving a change in the Al environment from tetrahedral to octahedral is frequently reported ammonium-exchanged zeolites after calcination, steaming, acid wash and other harsh treatments. We characterized Na-Y partially exchanged NH4-Y by spectroscopic diffraction methods order determine if NH4 exchange itself causes framework modification. High-resolution MAS SS NMR data show that even without some atoms their local octahedral. PDF analysis corroborates this shows an increase aluminium coordination number. TEM images no significant morphology of crystallites, major changes crystallinity are detected X-ray diffraction. A similar result obtained on Na-A zeolite suggesting such number during common feature zeolites. Local probes, environments framework, which usually not possible see average structure.