PARTICLE GENERATION IN A CHEMICAL VAPOR-DEPOSITION PROCESS WITH SEED PARTICLES

The formation of aerosol particles by gas‐phase chemical reaction in the presence of seed particles has been studied experimentally and theoretically. Titanium tetraisopropoxide (TTIP) vapor containing ultrafine TiO2 seed particles was introduced into a laminar flow aerosol reactor, and the properties of produced TiO2 aerosol were measured. By comparing the particle numbers and size distributions of the resulting aerosol with those of the seed particles and those of homogeneously nucleated particles in the absence of seed particles, the effects of initial concentrations of TTIP vapor, reaction temperatures, and properties of seed particles on the suppression of homogeneous nucleation were experimentally clarified. In the theoretical analysis, the population balance equation expressing simultaneous generation of TiO2 monomer, Brownian coagulation and diffusive deposition of TiO2 monomer and aerosols was solved. The observed suppression of homogeneous nucleation by the seed particles is explained qualitatively by the theoretical analysis. Copyright © 1990 American Institute of Chemical Engineers