Soot oxidation experimental kinetics: Comparison of experimental techniques

Thermo-Gravimetric Analysis (TGA) studies were performed with soot obtained from a mixture of mxylene and n-dodecane (10/90 in volume). The mixture was combusted under heavily-sooting conditions, C/O=0.83, in a flat flame premixed burner and the soot was oxidized using a Cahn TherMax 500 high pressure TGA. In this study test matrix was designed and executed in the TGA to develop an optimized experimental procedure at atmospheric pressure, which allows for the determination of the Arrhenius kinetic parameters. Experiments were carried out at O2 concentrations between 5 and 21%, sample amounts ranging between 5 and 30 mg, and volumetric flow rates between 0.5 and 1 l/min. An inert material (blasting zirconium silicate beads or black Silicon Carbide beads) was used in all the tests to minimize thermal and mass transfer effects by decreasing the stagnant region between the top surface of the soot and the entrance of the crucible. The activation energy was found to be on the same order of magnitude as other published values for the activation energy of uncatalyzed soot oxidation. These data were also compared with soot oxidation results obtained from a two-Stage burner. The results showed similar kinetic parameters.