Exploring the generation mechanism of soot from ammonia/diesel dual fuel engines under road transportation condition

Investigating the generation mechanism of soot in ammonia/diesel dual fuel engines under road transportation condition is beneficial for developing effective emission control strategies. This study analyzes the physicochemical properties of soot generated by an ammonia/diesel engine under road transportation condition, and further propose the effect mechanism of ammonia. The results show that the presence of ammonia enhances the oxidation activity of soot, with the peak temperature reducing from 418.2°C to 397.6°C. Ammonia significantly influences the content of aliphatic C-H, C=O and COOH functional groups on soot surface, and further promoting formation of nitrogen groups. Pyrrole nitrogen is transformed into pyridine nitrogen and quaternary nitrogen with a more stable structure with ammonia energy ratio increasing. In addition, ammonia weakens the hollow shell structure of soot and inhibits the growth of microcrystal length in the shell, resulting in a decrease of the degree of graphitization. However, an increase in the initial particle size of the soot particle is observed. Ammonia also affects the pore structure of soot, resulting in the decrease of mesoporous volume and specific surface area. This study contributes to control soot emission from ammonia/diesel engines, and further evaluating the environmental effects.