Kinetics of the Titanium Isopropoxide Decomposition in Supercritical Isopropyl Alcohol

The formation of TiO 2 powder from Ti(O-iC 3 H 7 ) 4 dissolved in supercritical isopropyl alcohol has been studied. Kinetic data were obtained 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 used as solvent and where the limiting steps are the decomposition reactions of the formed titanium hydroxides. In accordance with experimental results, such a mechanism leads to a first order kinetics relative to the precursor concentration. The activation energy was determined equal to 113 ± 16 kJ·mol -1, and an increase in the supercritical fluid density was found to decrease the overall reaction rate. The obtained results will be used to optimize the working of a continuous reactor producing submicronic TiO 2 powder at a laboratory pilot scale.