Global kinetics for the oxidation of diesel fuel (DF), propylene (C3H6), CO, H2, and NO were determined
over a commercial diesel oxidation catalyst (DOC) with simulated diesel exhaust between 200 and 415 °C
over a wide concentration range intended to represent engine exhaust from both conventional and premixed
compression ignition (PCI) combustion. Total hydrocarbons in the exhaust were represented as a combination
of propylene, to represent partially oxidized fuel species, and diesel fuel, to represent unburned fuel. An
integral reactor with high space velocity capability (up to 2 million h-1) was used to generate low and moderate
conversion data for the rate-generation process. Mass transport properties of DF were determined based on
the experimental data. First-order concentration dependency for all of the reactants involved in the DF, C3H6,
CO, and H2 oxidation reactions adequately captured the experimental behavior. An overall inhibition term
including only the effects of CO and NO was found to be adequate for these reactions over the range of
conditions examined for this study. For the NO oxidation reaction, the rate was found to be first order with
respect to NO and 0.5 with respect to O2. The inhibition term for this reaction was found to be a function of
DF and NO. Modeling approaches and optimization strategies similar to our previous work1 were employed
for the entire rate-generation process. These rate expressions were first validated against light-off curves
generated with the same laboratory reactor operating at realistic space velocities and subsequently validated
against light-off curves generated on a full-size DOC mounted on a 1.7 L Isuzu diesel engine using both
conventional and PCI combustion strategies.