《1991Vapor synthesis of titania powder by titanium tetrachloride oxidation》.pdf

Vapor Synthesis of Titania Powder by Titanium Tetrachloride Oxidation M. Kamal Akhtar, Yun Xiong, and Sotiris E. Pratsinis Dept. of Chemical Engineering, Center for Aerosol Processes, University of Cincinnati, Cincinnati, OH 45221 Formation of titania particles by vapor-phase oxidation of titanium tetrachloride was studied in an aerosol reactor between 1,200 and 1,723 K. The effect ofprocess variables (reactor residence time, temperature, and reactant concentration) onpow- der size and phase characteristics was investigated using the differential mobility particle sizer, scanning electron microscopy, and X-ray diffraction. Titania particles wereprimarily anatase though the rutile weightfraction increased with increasing reactor temperature. The geometric number average diameter of theparticles was between 0.13 and 0.35 pm, and the geometric standard deviation of theparticle size distribution was about 1.4. The averageparticle size increased with increasing tem- perature, inlet TiC1, concentration, and residence time. The observed changes in the particle size distribution were compared with thosepredicted by solving the aerosol dynamic equation by a sectional method and accountingfor coagulation andfirst- order chemical reaction. While variations in the process variables resulted in dis- cernible changes in the size of theparticles, the spread of the distribution remained r