Regeneration of diesel particulate filter (DPF) is a complicated process due to its high operating temperature and associated oxidation of soot on the filter substrate. Several oxidation mechanisms of diesel soot have been proposed based on reaction kinetics, but more information about the oxidation phenomena is needed in a practical system, that is, soot oxidation on a DPF substrate. In this work, the DPF regeneration process was, for the first time, visualized at the particle scale ex‐situ, in time‐lapse series, using field emission scanning electron microscopy (FE‐SEM). Time‐lapse transformation of soot cake layer on a real DPF was followed from initiation through the complete regeneration process. In parallel, transformation of the soot primary particle diameter was directly measured using high‐resolution transmission electron microscopy. FE‐SEM visualization clearly showed shrinkage of the soot cake layer on the DPF wall as oxidation progressed. Furthermore, diameter distribution analysis revealed a trend of shrinkage of the nanoscale soot primary particles during oxidation, supporting the FE‐SEM observations of the micron‐scale shrinkage of the agglomerated soot cake layer. Fragmentation of the shrunken soot cake layer was also observed and is suspected to be a result of locally higher gas flow that depends on surface pore morphology of the filter substrate.

中文翻译：

---

使用场发射扫描电子显微镜对柴油微粒过滤器主动再生的延时可视化

柴油微粒过滤器 (DPF) 的再生是一个复杂的过程，因为它的工作温度高，而且过滤器基材上的烟尘会被氧化。已经根据反应动力学提出了几种柴油烟尘氧化机制，但在实际系统中需要更多关于氧化现象的信息，即 DPF 基材上的烟尘氧化。在这项工作中，DPF 再生过程首次使用场发射扫描电子显微镜 (FE-SEM) 在颗粒尺度异位、延时系列中可视化。从开始到完整的再生过程，跟踪真实 DPF 上烟灰饼层的延时转换。同时，使用高分辨率透射电子显微镜直接测量烟尘初级粒径的转变。FE-SEM 可视化清楚地显示随着氧化的进行，DPF 壁上的烟灰饼层收缩。此外，直径分布分析揭示了纳米级烟尘初级粒子在氧化过程中的收缩趋势，支持了对团聚烟尘饼层微米级收缩的 FE-SEM 观察。还观察到收缩的烟灰饼层的碎裂，并且怀疑是局部较高气流的结果，该气流取决于过滤器基材的表面孔隙形态。支持 FE-SEM 观察到团聚烟饼层的微米级收缩。还观察到收缩的烟灰饼层的碎裂，并且怀疑是局部较高气流的结果，该气流取决于过滤器基材的表面孔隙形态。支持 FE-SEM 观察到团聚烟饼层的微米级收缩。还观察到收缩的烟灰饼层的碎裂，并且怀疑是局部较高气流的结果，该气流取决于过滤器基材的表面孔隙形态。