KINETICS OF THE TITANIUM ISOPROPOXIDE DECOMPOSITION IN SUPERCRITICAL ISOPROPYL-ALCOHOL

The formation of TiO2 powder from Ti(O-iC(3)H(7))(4) dissolved in supe rcritical isopropyl alcohol has been studied. Kinetic data were obtain ed in a temperature range of 531-568 K. A reaction mechanism has been proposed, based on a hydrolytic decomposition of Ti(O-iC(3)H(7))(4) by water produced in a catalytic dehydration of the isopropyl alcohol us ed as solvent and where the limiting steps are the decomposition react ions of the formed titanium hydroxides. In accordance with experimenta l results, such a mechanism leads to a first order kinetics relative t o the precursor concentration. The activation energy was determined eq ual to 113+/-16 kJ . mol(-1), and an increase in the supercritical flu id density was found to decrease the overall reaction rate. The obtain ed results will be used to optimize the working of a continuous reacto r producing submicronic TiO2 powder at a laboratory pilot scale.