Soot reactivity and regeneration mechanism of modern automobile engines and methods of reducing soot emission for diesel particulate filter: A review

With the increasingly stringent environmental regulations on road traffic, the emission standards for particulate matter from internal combustion engines have risen significantly. Consequently, the implementation of particulate filters to capture or regenerate combustion particles has become imperative. This review examines the factors influencing soot reactivity and its impact on DPF regeneration. Soot is comprehensively evaluated through various analytical methods, including structural, chemical, and thermal characterization. The overall analysis reveals that diesel particulate filter (DPF) regeneration is primarily governed by the physicochemical properties of soot, with primary particle size and nanostructural order serving as key morphological parameters determining specific surface area and oxidation rate. Notably, fuel formulation significantly affects these characteristics, with biodiesel-derived soot typically exhibiting higher structural order and smaller particle size. Thermogravimetric analysis is established as an effective tool for predicting DPF regeneration behavior. Consequently, earlier studies correlating reactivity with limited soot properties may be incomplete, highlighting the necessity of adopting multidimensional characterization approaches. To advance DPF regeneration, future research could integrate AI models, in-situ diagnostics, and tailored catalysts, with the aim of developing a smart closed-loop system to better manage soot reactivity.