TRANSITION METAL-SILICATE ANALOGS OF ZEOLITES

The synthesis and characterization of three transition metal (Fe3+, Ti4+ and V4+)-silicate molecular sieves are discussed. The key factors for a successful incorporation of these metal ions in the growing silicate network during gel preparation/hydrothermal synthesis (e.g. avoidance of insoluble/sparingly soluble metal hydroxides/oxyhydroxides (Fe3+ and Ti4+) and alkali metal ions (Ti4+ and V-4+/5+)) as well as the effects of post synthesis drying, calcination etc. on the stability of these metal ions in the framework are evaluated. Various spectroscopic and other techniques which are required to provide general as well as specific structural and textural information about the fate of these transition metal ions are discussed.