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Influence of maturity on the oxidation kinetics and nanostructure evolution of soot sampled from a propane coflow diffusion flame

Year: 2025
Type: article
Abstract: Exploration of soot oxidation kinetics at different soot maturity stages is significant for understanding nucleation mechanisms, controlling growth rates, and improving removal efficiency. However, there is still a limited understanding of the oxidation mechanisms for early-stage soot. This work investigates the oxidation kinetics and nanostructure evolution of soot particles sampled from a laminar co-flow diffusion flame of propane with two distinct residence times. Efficient sampling of both early-stage soot and mature soot are performed by using our recently developed capillary-nozzle-hybrid sampling method, which can achieve high sampling efficiency and reduced perturbance to flames simultaneously. Kinetic parameters are evaluated from non-isothermal thermogravimetric data at different heating rates, revealing that early-stage and mature soot present distinct oxidation reactivity. Within the conversion rates of 20%−90%, the oxidation activation energy of mature soot distributes within 160−185 kJ/mol, which grows monotonically with the conversion rate and has a slower and slower growth rate. The oxidation activation energy of early-stage soot has much lower values, distributing from 128 to 156 kJ/mol with a multi-stage dependence on the conversion rate. The variation in soot nanostructure during oxidation is monitored within a 75% conversion rate. Mature soot presents the combined modes of surface and internal oxidation, which results in declined particle diameters and disordered nanostructure. In contrast, early-stage soot merely presents surface oxidation mode with the nanostructure being more and more organized.
DOI: 10.48130/prkm-0025-0001
Language: English
Open Access status: diamond
OpenAlex ID: W4409375952
FWCI: 2.487
Cites: 60
Cited by: 8
Related to: 10