LAUSR

Abstract The impact of engine operating cycle, Biodiesel blends and fuel impurities on soot production and soot properties are evaluated in the present work. To this end, soot were produced on engine test bench and then collected inside a Diesel Particulate Filter (DPF). Two engine cycles (a Natural Loading and an Accelerated Loading) were tested. A standard Euro VI fuel blended with 7% of Biodiesel (B7) and a pure Biofuel (B100 RME EN 14214) were used. This latter was additivated with potassium and phosphorus at a low (B100+) or at a high (B100++) concentration. Soot characterization through elemental analyses, nitrogen adsorption, Raman spectroscopy, TGA and TPO experiments show that the engine operating cycle impact the soot reactivity through modifications of their texture and structure. Test bench experiments also show that increasing Biodiesel blend from B7 to B100+ divides by five the soot production. Moreover, soot obtained with B100+ are more reactive because of higher oxygen and ash content. When the inorganic content of the fuel is increased, few effects on the soot production are observed but the soot reactivity is significantly increased. In fact, analyses highlight that impurities present in the fuel are retrieved inside the soot composition and then catalyze their oxidation. K has a beneficial effect on both passive and active regenerations. On the contrary, P inhibits the active regeneration but has a significant catalytic impact on the C NO2 H2O reaction. Finally, a numerical simulation allows to extract the kinetic constants of real B7- and B100+-soot, whose values confirm the differences of the soot reactivity.