Morphology and structure of nanosized TiO2 particles synthesized by gas-phase reaction

Nanosized titania particles are synthesized by the gas-phase oxidation of titanium tetrachloride in a high temperature tubular aerosol flow reactor that consists of two preheaters for oxygen and vaporized titanium tetrachloride, a reaction zone, and a cooling zone for particles. The effect of process parameters on the morphology and structure of titania particles is studied. As the preheating temperature of oxygen increases, the average particle size of titania decreases and the size distribution becomes more uniform. The addition of AlCl3 can reduce the particle size, and enhance the rutile weight fraction. The effect of reaction temperature (T) on the characteristics of nanosized titania particles is also investigated. The results show that the particle size increases with increasing temperature, acid a maximum rutile fraction is attained at 1200 degrees C and AlCl3 and TiCl4 feed ratio (X-inlet) of 0.09. Pure rutile titania particles is formed when T=1373 K and X-inlet=0.25. The average grain size of the particles is 29.0 nm, and the BET specific surface area is 23.4 m(2) g(-1). (C) 2000 Elsevier Science S.A. All rights reserved.