Zeolite Structure Analysis with Powder X-ray Diffraction and Solid-state Nmr Techniques

Large advances in the development of catalytic materials were made with the synthesis of zeolites, which are porous crystalline materials that can be used as catalysts, catalyst supports, sorbents and ion exchangers. Zeolite structures consist of T-atoms tetrahedrally coordinated to oxygen atoms, where T can be AI, Si, or any other element capable of isomorphous substitution for Si. The unavailability of good quality, large single crystals makes the powder diffraction technique essential. Originally the powder diffraction patterns of these materials were used as fingerprints, but on careful analysis and with improved diffraction techniques a wealth of information may be derived from these data. The availability of rotating anode and synchrotron X-ray and neutron sources and the application of the Rietveld refinement method results in considerable improvement in the quality of structural information that can be derived. Further, the application of solid-state NMR techniques in conjunction with the X-ray diffraction method greatly increases the short-range-order information obtainable from these systems.