Structure-reactivity study of model and Biodiesel soot in model DPF regeneration conditions

The aim of the present work is to investigate and compare the non-catalytic and catalytic reactivities of real and model soot samples through temperature-programmed oxidation (TPO). Such reactivity was furthermore correlated with soot structural properties, determined by laser granulometry, XRD, Raman and HRTEM. Biodiesel soot samples were obtained through the combustion of different fuels in a real engine, whereas model soot samples were produced in a laminar burner. TPO evidenced that the soot generated with 100% Biodiesel (methyl ester) was more reactive than real soot generated with 7% Biodiesel (7% methyl ester). The model soot from the diesel surrogate (Aref) containing 7% oxygenate additive (C11H22O2) exhibited higher reactivity than the model soot containing 30% additive, whereas a carbon black (Degussa Printex U) showed the poorest reactivity of this series. The presence of NO2 promoted the non-catalytic oxidation of real soot. In the presence of the MnOx-CeO2 catalyst, soot reactivity depended both on reactant gas composition and on soot-catalyst contact.