The effect of deposit morphology on soot oxidation in non-catalytic and catalytic processes

Investigating the oxidation behavior of soot particles with varying deposit morphologies is crucial for understanding the mechanisms behind uneven regeneration in diesel particulate filters and enhancing regeneration strategies. This study explores the impact of two distinct deposit morphologies on soot oxidation within non-catalytic and catalytic processes, with a particular focus on the associated changes in pore structure during oxidation. Findings indicate a minimal difference in oxidation activity between loose and compacted soot particles in non-catalytic oxidation, while a significant enhancement in oxidation activity is observed for compacted soot particles during catalytic oxidation. Specifically, compacted soot particles exhibit a pronounced reduction in total pore volume, particularly in macropores, and a shift in pore size distribution towards smaller diameters during non-catalytic oxidation. In the catalytic oxidation process, compacted soot particles predominantly form 2–10 nm mesopores, with limited formation of pores larger than 10 nm. Oxidation activity in the non-catalytic process positively correlates with pore volume, especially for 100–200 nm macropores. In contrast, during catalytic oxidation, oxidation activity inversely relates to pore volume, emphasizing the critical role of catalyst-soot contact in catalytic oxidation efficiency.