Effects of Reaction Conditions on the Oxidation Behavior of Soot Particles: A Molecular Dynamics Study Based on Realistic Particle Structures
Abstract Soot is widely present in combustion systems, yet its oxidation mechanisms remain unclear due to complex internal structures. Core–shell soot models with different maturity levels are constructed using high-resolution transmission electron microscopy. Furthermore, the effects of reaction conditions on soot oxidation behavior are revealed by large-scale molecular simulations. Competition between internal oxygen diffusion and heterogeneous carbon oxidation governs reactivity. Upon annealing at 1600 °C for 4 h and with increasing soot maturity, the complete oxidation time increases by 49.5%, while the peak reaction rate decreases by 55.1%, indicating stronger resistance of ordered structures to oxygen transport. A three-region oxidation criterion is proposed, including an oxygen-limited stage, a rapid core oxidation stage, and a residual shell oxidation stage. Lower temperatures and pressures favor internal preferential oxidation, whereas higher severity promotes shrinking-core behavior. These results establish a structure-condition-reactivity relationship and enable prediction of oxidation-mode transitions and optimization of soot conversion.