Influence of temperature schedules on particle size and crystallinity of titania synthesized by vapor-phase oxidation route

Crystalline TiO2 particles were produced in a tubular flow reactor by chemical vapor synthesis using titanium tetrachloride as a starting material in oxygen containing atmospheres. The dependence of particle size, morphology and crystalline phase of titania on temperature schedules including the reactor temperature, the oxygen preheated temperature and the product cooling measure were explored. It is found that there are two opposite effects of temperature on particle size and crystalline phase content. The particle size distribution, SEM and TEM of resulting powders show that the grain size is controlled by the relative magnitudes of the nucleation rate and growth rate, both of them being subject to the temperature schedules. XRD indicates that particles crystalline phase is predominately anatase and the rutile content increment is not consistent with temperature increase. Anatase titania can be converted to rutile by addition of crystal modifier AlCl3. The element analysis by EDS shows that Al enriches on the particle outer surface.

Crystalline TiO2 particles were produced in a tubular flow reactor by vapor synthesis using titanium tetrachloride as a starting material in oxygen containing atmospheres.The general reaction is: TiCI4 + O2 → TiO2 + 2Cl2.The dependence of particle size, morphology and crystalline phase of titania on temperature schedules including the reactor temperature, the oxygen preheated temperature and the product cooling measure was explored. It is found that there are two opposite effects of temperature on particle size and cystalline phase content. The particle size distribution, SEM and TEM of the resulting powders show that the grain size is controlled by the relative magnitudes of the nucleation rate and growth rate, both of them being subject to temperature schedules. XRD indicates that particles crystalline phase is predominately anatase and the rutile content increment is not consistent with temperature increase. Anatase titania can be converted to rutile by the addition of crystal modifier AICI3. The element analysis by EDS shows that AI enriches on the particle outer surface. Figure optionsDownload as PowerPoint slideFig. 5. Schematic of gas-to-particle conversion process.