Hydrothermal synthesis of microporous titanosilicates

Titanosilicates of various framework topology are synthesized in the template-free Na2O–(K2O)–TiO2–SiO2–H2O system. The fields of crystallization of the as-synthesized phases are outlined and the role of certain physicochemical parameters on the framework type, crystal size and morphology as well as crystal aggregate texture of the run-products is studied. Kinetic investigations carried out in the potassium-free system give insights on the atomic arrangements in the amorphous sodium titanosilicate precursor powders, their evolution upon hydrothermal treatment and the related phase formation sequence. The synthesis results reveal possible mechanisms of increasing the structural diversity of synthetic heterosilicates with desired pore system and functionality by varying the composition of framework and extraframework cations and appropriate adjusting of the pH and temperature of reaction medium.