Experimental verification of direct surface reaction model in an aerosol reactor

Abstract

Nanometer-sized titania particles were prepared by thermal decomposition of titanium tetraisopropoxide (TTIP) in a furnace type aerosol reactor. Direct surface reaction (DSR) model was introduced because simple reaction coagulation (SRC) model, which is valid at high conversion, was found to be improper at high concentration and low conversion. The size of titania particles increased from 10 to 60 nm with increasing input concentration of TTIP from 7×10-10 to 2×10-8 mol/mL. Experimentally, the particle size was proportional to the 0.46th power of the precursor concentration and this result was closer to the prediction of DSR model than that of the SCR model. The SCR model predicted that the exponent was 0.171. The diameter of product particles was decreased from 55 to 30 nm as the reaction temperature was increased from 250 to 550����C. The DSR model predicted the decreasing trend of the particle size with increasing temperature, whereas the SRC model simulation predicted that the size was an increasing function of the temperature.