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Title: NO 2 oxidation reactivity and burning mode of diesel particulates

The NO 2 oxidation kinetics and burning mode for diesel particulate from light-duty and medium-duty engines fueled with either ultra low sulfur diesel or soy methyl ester biodiesel blends have been investigated and are shown to be significantly different from oxidation by O 2. Oxidation kinetics were measured using a flow-through packed bed microreactor for temperature programmed reactions and isothermal differential pulsed oxidation reactions. The burning mode was evaluated using the same reactor system for flowing BET specific surface area measurements and HR-TEM with fringe analysis to evaluate the nanostructure of the nascent and partially oxidized particulates. The low activation energy measured, specific surface area progression with extent of oxidation, HR-TEM images and difference plots of fringe length and tortuosity paint a consistent picture of higher reactivity for NO 2, which reacts indiscriminately immediately upon contact with the surface, leading to the Zone I or shrinking core type oxidation. In comparison, O 2 oxidation is shown to have relatively lower reactivity, preferentially attacking highly curved lamella, which are more reactive due to bond strain, and short lamella, which have a higher proportion of more reactive edge sites. Furthermore, this preferential oxidation leads to Zone II type oxidation, where solid phasemore » diffusion of oxygen via pores contributes significantly to slowing the overall oxidation rate, by comparison.« less
 [1] ;  [2] ;  [3] ;  [4] ;  [4]
  1. Texas A & M Univ., College Station, TX (United States); Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)
  2. Penn State Univ., University Park, PA (United States)
  3. Texas A & M Univ., College Station, TX (United States)
  4. Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)
Publication Date:
Grant/Contract Number:
Accepted Manuscript
Journal Name:
Topics in Catalysis
Additional Journal Information:
Journal Volume: 59; Journal Issue: 8-9; Journal ID: ISSN 1022-5528
Research Org:
Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States). Fuels, Engines and Emissions Research Center (FEERC); Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States). National Transportation Research Center (NTRC)
Sponsoring Org:
USDOE Office of Energy Efficiency and Renewable Energy (EERE)
Country of Publication:
United States
33 ADVANCED PROPULSION SYSTEMS; soot oxidation; passive oxidation; biofuel; diesel soot; NO2 oxidation; nanostructure; HRTEM
OSTI Identifier: