(180c) Investigation of burning mode for diesel particulate oxidation: contrasting O2 and NO2

The physical  characteristics  of diesel  particulates  from  conventional  diesel,  biodiesel  and
blends  of  the  two  were  investigated  at  several  points  along  the  O2 and  NO2 oxidation reactions. BET measurements  elucidated the surface area evolution with extent of oxidation for the two oxidizers and revealed differences in surface area evolution in the samples when oxidized  with O2.  Particulate  matter  from  biodiesel  initially  has greater  surface  area  than particulate   from  ULSD,  an  advantage,   which  is  maintained  under  O2  oxidation  until approximately 40% of the sample has been consumed. HR -TEM and fringe analysis confirm that  initial  differences  in  the  lamella  lengths  have  disappeared  by  40%  burnout  of  the samples. TEM images suggest that surface area evolves mostly internally for O2 oxidation as the primary particle diameters do not follow the shrinking core trajectory. However, for NO2 there are no sample-specific  dependencies in either reactivity and surface area. TEM images
suggest that NO2 oxidation occurs by a mostly external trajectory.