Synthesis of silica-carbon particles in a turbulent H2-air flame aerosol reactor

Synthesis of flame-made nanostructured powders was studied, for the first time, at high production rates (up to 700 g/h) in a turbulent diffusion flame reactor, addressing also the required safety concerns. A commercial hydrogen-air burner was used for synthesis of pure silica and composite silica-carbon particles by oxidation of hexamethyldisiloxane. The product powder was collected continuously in a baghouse filter unit and cleaned periodically by air-pressure shocks. The effect of the fuel (hydrogen) flow rate, powder production rate and total oxidant flow rate on product particle size, morphology, and composition was also investigated. Nitrogen adsorption, transmission electron microscopy and thermogravimetric analysis coupled with a mass spectrometer, ans a CO2-analyzer were employed to characterize specific surface area and powder composition. Typically, aggregates of silica-carbon composite particles (0 to 1.4 wt.% carbon) were made on specific surface areas of 75 to 250 m(2)/g at production rates of 125 to 700 g/h, which correspond to particle concentrations of 17 to 93 g/m(3) (2-10% solid fraction by weight).