Influence of Diesel Fuel Characteristics on Soot Oxidation Properties

This study provides an overview on the impact of fuels on certain soot characteristics, such as oxidation behavior and morphology. The aim is to understand how fuel parameters affect the ease at which soot can be oxidized. The oxidation behavior of soot samples obtained from different types of diesel fuel was determined by means of Temperature Programmed Oxidation in a Thermo-Gravimetric Analyzer and a six-flow reactor; the structural morphology of soot was examined via Transmission Electron Microscopy. The soot oxidation temperature was found to be dependent to a great extent on the type of the diesel fuel, when oxygen is the only oxidant with or without a Pt-catalyst upstream. Soot oxidation in the presence of NO and a Pt-catalyst upstream resulted in a reduction in the oxidation temperature; this environment also led to smaller differentiation between the soot samples compared with the pure oxygen conditions. The amount of sulfur in the fuel had only a minor impact on the soot oxidation temperature, whereas the aromatic compound content affected this temperature significantly. A low-aromatic fuel results in a soot with a significantly higher oxidation temperature than a fuel with a large amount of aromatics (particularly diaromatics). This may have an impact on induced diesel soot abatement and regeneration strategies in automotive Diesel Particulate Filters as well as on the design of a new class of diesel fuels.