Nanostructured titania powders by hydrothermal processing and spray drying.

Sol-gel precipitates of titania were prepared from organometallic precursors, followed by hydrothermal crystallization and spray drying into spherical, micron-size nanostructured granules that were characterized by X-ray diffraction, nitrogen adsorption, and microscopy. A systematic investigation of the effect of hydrothermal processing conditions on the physical properties of the granules was carried out. When the hydrothermal processing time was increased, product granules exhibited larger anatase crystallite size and improved thermal stability in pore structure and phase composition. Increasing the hydrothermal processing temperature retarded crystallite growth and increased the anatase-to-rutile transformation temperature.