EFFECTS OF ALCOHOL ADDITION ON THE PYROLYSIS OF TITANIUM TETRAISOPROPOXIDE AND FORMATION OF TITANIA PARTICLES

Generation of titania particles by thermal decomposition of a mixture of titanium tetraisopropoxide (TTIP) and tert-butanol was carried out in an aerosol reactor. The reactor wall was initially coated with titania which catalyzes the thermal decomposition of TTIP and tert-butanol. Tert-butanol was added to alter the kinetics of TTIP decomposition and to control particle size. Both the conversion of TTIP and the mean size of titania particles decreased with increasing fraction of tert-butanol in the mixture. The conversion of TTIP was varied from 0.75 to 0.95 and the mean size of the titania particles produced ranged between 40 and 80 nm depending on the input TTIP mole concentration and mole fraction of tert-butanol. When only tert-butanol was decomposed in a titania-coated reactor, the decomposition rate was faster than pure TTIP. In the case of isopropanol, however, the decomposition rate was comparable to that of TTIP and it did not affect the apparent reaction rate of TTIP. We concluded that the competition between TTIP and tert-butanol on the titania surface altered the conversion process and the particle size. The experimental results demonstrate that we can control the particle size with high precision by making two reactants compete in the course of reactions in an aerosol reactor.