The role of ferrocene in flame synthesis of silica

The effect of ferrocene additive on the specific surface area of silica particles synthesized in a diffusion flame reactor was studied. Three different mixing configurations of the reactant gases were investigated. The SiCl4 mole fraction in the flame was varied from 1.2 × 10−3 to 4 × 10−3. Ferrocene concentrations in the flame ranged from 4 × 10−8 to 6 × 10−7 mol/L. The ferrocene/SiCl4 mole ratio was varied from 0.004 to 0.09. Silica particles collected from ferrocene-doped flames had a higher specific surface area compared with particles produced in the absence of ferrocene. The specific surface area was enhanced up to 150% depending on the reactant mixing and the silica and ferrocene loadings in the flame. Ferrocene was more active at intermediate loadings. Furthermore, ferrocene was found to remove the coarse tail of the silica aggregate size distribution.