Abstract
BACKGROUND: For compliance with the regulations on diesel particulate matter, car manufacturers have developed diesel particulate filters (DPF). These technologies require a regeneration method which oxidizes soot deposits in the filter. In diesel exhaust emissions there are two suitable oxidizing gases: oxygen and nitrogen dioxide. Nitrogen dioxide is much more active than O~2~ and can directly attack the carbon surface. This work describes the kinetics of the oxidation of soot by NO~2~ over a wide range of conditions relevant for DPF.
RESULTS: The catalyzed and the non‐catalyzed oxidation of soot have been performed in a fixed‐bed reactor. The experimental results show that the overall oxidation process can be described by two additive parallel reactions: a direct C − NO~2~ reaction catalyzed by H~2~O and a cooperative C − NO~2~ − O~2~ reaction catalyzed by the Pt/Al~2~O~3~ catalyst. The results obtained allow to propose the following kinetic law for the specific rates of the catalyzed and the non‐catalyzed oxidation of soot in the regeneration filter conditions:
CONCLUSION: The kinetic parameters describing the oxidation rate of soot by NO~2~ over a range of temperature and gas composition have been obtained. The extracted kinetics data are relevant for modeling the removal of trapping soot in automotive gas exhaust technology. Copyright © 2009 Society of Chemical Industry