Titania formation by TiCl4 gas phase oxidation, surface growth and coagulation

Titania particle formation by TiCl4 gas phase oxidation, surface growth and coagulation is investigated by a moving sectional population balance model. The dynamic evolution of the detailed particle size distribution is studied accounting for and neglecting the effect of surface growth. The effects of process temperature, T, and precursor volume fraction, phi, on the average diameter, d(p), and geometric standard deviation of the particle size distribution are highlighted. Accounting for surface reaction accelerates particle growth for phi >0.01 and gives a size distribution narrower than the self-preserving one as long as the precursor conversion is less than 99%. At higher conversions, the particle size distribution reaches the self-preserving limit corresponding to aerosols made by coagulation. A monodisperse model represents well aerosol dynamics at high process temperatures. A design diagram summarizing the significance of surface reaction in terms of phi and d(p) at various process temperatures is presented. (C) 2001 Elsevier Science Ltd. All rights reserved.