Phase transformation and porosity characteristics of chemically modified Sol-Gel titania with respect to silica addition

TiO₂-SiO₂ gels were prepared through the hydrolysis and polycondensation of a mixture of titanium isopropoxide and tetra ethoxy silane (TEOS) in presence of a gel modifier such as acetic acid. The resultant titania-silica gel precursor was calcined at various temperatures. An attempt has been made to correlate the properties of the resultant oxide with silica content. The amorphous to anatase and the anatase to rutile phase transition was followed by X-ray diffraction studies. The specific surface area of the resulting oxides was measured by BET method. 20% silica addition enhanced the specific surface area of titania from 84 m².g⁻¹ to 345 m².g⁻¹. The mesoporous nature of titania changes to microporous one, after addition of silica. Anatase to rutiie transformation temperature has also been influenced by the addition of silica.