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 ceri um 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 eith er under linear heating rate conditions (2 K/min) or isothermally up t o 750 degrees C. The cerium (as cerium oxide) strongly decreases the i gnition temperature of the soot. The influence of the Ce content of so ot on the kinetics of oxidation is described and the experimental temp eratures of soot ignition are compared with the values derived from th e Semenov theory.