Preparation of titania mesoporous materials using a surfactant-mediated sol-gel method

Small titania particles were generated within the template of non-ionic surfactant (TX-100) reverse micelle assembly by the sol-gel method from titanium(IV) isopropoxide. Cyclohexane was used as the reaction solvent to form a reverse micelle system with a low water to surfactant ratio. Gelling, i.e., hydrolysis and polycondensation, were observed by viscosity measurements. The transparent raw gels obtained were dried under vacuum at 372 K. The dry gels were then either thermally decomposed directly to TiO2 or the organic content (surfactant) was substantially reduced first by supercritical fluid extraction with CO2 and then heat treated. Special attention was paid to the effect of temperature on the extent of crystallisation of individual crystallographic phases of TiO2. Gels, partly decomposed gels and gels after supercritical fluid extraction were investigated by XRD, XPS, IR, TPR, thermogravimetry, mass spectrometry, elemental analysis, UV-vis, SEM and extensive gas adsorption measurements. Their properties were related to the structure and other features of the final nanosized TiO2 particles. The anatase form of TiO2 with a very high specific surface area and well-developed mesoporous and microporous structure was prepared. 67 refs.