Variation of Soot Structure Along the Exhaust Aftertreatment System—Impact of Oxygenated Diesel Blends on the Soot/Catalyst Interactions

Abstract

Particulate matter structural modifications do not only impact the oxidative/mutagenic properties of the particulates but also influence the motion and contact between the aggregates in the exhaust. Those interactions have a direct impact on the porosity, permeability, and packing density of the soot cake deposited in the diesel particulate filter (DPF). This in turn will influence the filtration efficiency and pressure drop in the DPF channels. Morphology of the PM combined with the carbon layer nanostructure also has a direct impact on the DPF regeneration capability. After recognizing the importance of the particulates’ structure on the DPF performance, it becomes a subject of interest to understand if the engine-out PM will face any modifications within the aftertreatment units, e.g., diesel oxidation catalyst, selective catalytic reduction catalyst, etc., before being trapped in the DPF. While the dependency of the PM characteristics on its fueling source and engine technology is a well-researched topic, limited work has been carried out regarding the impact of the aftertreatment system on the structure (i.e., morphology and nanostructure) and chemical characteristics of the exhaust PM. This chapter will discuss the different theories and experimental work provided in the literature regarding the impact of aftertreatment systems on the PM characteristics. Special attention will be given on the impact of alcohols and other oxygenated fuels on this mechanism compared to conventional diesel fuel.KeywordsAlcoholSootParticulate matterDPFDOCSCRAftertreatment