Influence of cerium oxide on the formation and oxidation of soot

Soot was produced by pyrolysis and oxidative pyrolysis of hydrocarbons doped with cerium organometallic compounds. More than 90% of the cerium is found in and on the soot particles. Soot containing up to 10% Ce by weight was prepared. The presence of cerium-based compounds has no effect on the yield or the morphology of soot. The soot samples were oxidized by oxygen diluted in an inert gas at 5% to 20% by volume either under linear heating rate conditions (2 K/min) or isothermally up to 750°C. The cerium (as cerium oxide) strongly decreases the ignition temperature of the soot. The influence of the Ce content of soot on the kinetics of oxidation is described and the experimental temperatures of soot ignition are compared with the values derived from the Semenov theory.