Studies on the Effect of Physico-Chemical Soot Properties and Feed Gas Composition on the Kinetics of Soot Oxidation on Fe sub(2)O sub(3) Catalyst

Three commercial carbon black samples as well as self-made C sub(3)H sub(6) soot were investigated for their reactivity in the oxidation on an alpha -Fe sub(2)O sub(3) catalyst. These studies were performed by temperature programmed oxidation (TPO) using a packed bed. For reference purposes, TPO studies in the absence of the catalyst were made as well. The carbon black samples were characterized towards the content of C, H, N and O as well as higher heating value, specific surface area, moisture and volatile matter and were deemed to be suitable model substances for diesel soot of different maturity. The correlation of these physico-chemical properties with the kinetics in catalytic TPO indicated that the soot oxidation on Fe sub(2)O sub(3) is significantly affected by the initial number of surface oxygen compounds of the soot. The decomposition of these surface species causes the formation of active carbon sites, which are supposed to accelerate the soot oxidation. Four carbon blacks as models for diesel soot at different maturity stages were studied towards their oxidation reactivity in the absence and presence of a Fe sub(2)O sub(3) catalyst. The kinetics of the catalytic oxidation of the carbon black samples could be correlated with their number of initial surface oxygen compounds. The influence of typical exhaust gas components on catalytic soot oxidation reactivity was also addressed.