Study on the nano-structure characteristics of particle before and after diesel oxidation catalyst for diesel engines

ABSTRACT

Diesel Oxidation Catalyst (DOC) is the most important and advanced part of the after-treatment technology route. After the exhaust passes through DOC, CO, and HC will be significantly reduced, while particles are mainly captured by the Diesel Particulate Filter (DPF) device behind. In order to further investigate the effect of DOC on the nano-structure characteristics of diesel emission particles. The particles before and after DOC of 186FA diesel engine at 2700 r/min, 100% load, and 3600 r/min, 100% load are collected. The nano-structure characteristics of particles are investigated using field emission transmission electron microscopy (FETEM) combined with small angle X-ray scattering radiation technique (SAXS). Based on FETEM and SAXS analysis of particles, a nano-scale particle spatial structure model including particle size, pores, and visual boundary layer is proposed. The results show that the average radius, interface layer thickness, and fractal dimension of the particles are reduced after the DOC. In contrast, the specific surface area of the particles is increased after the DOC. At 3600 r/min 100% load, the average radius is reduced from 23.3 to 21.5 nm, accounting for 7.8%. Interface layer thickness is reduced from 13.3 to 12.9 nm. The specific surface area of the particles is increased from 0.146 to 0.166 m²/mm³. The research results provide a theoretical basis for the regeneration and oxidation of particles in DPF.

KEYWORDS:

• Diesel engine
• particle
• small angle X-ray scattering
• structure characteristic
• emissions
• diesel oxidation catalyst (DOC)

Acknowledgements

This study was financially supported by the project of natural science foundation of Jiangsu province (BK20200910), open project of state key laboratory of engines (Tianjin University) (K2020-12), provincial engineering research center for new energy vehicle intelligent control and simulation test technology of Sichuan (XNYQ2021-003) and state key laboratory of automotive safety and energy (KFY2227).

Disclosure statement

No potential conflict of interest was reported by the author(s).

Additional information

Funding

This work was supported by the provincial engineering research center for new energy vehicle intelligent control and simulation test technology of Sichuan [XNYQ2021-003]; open project of state key laboratory of engines (Tianjin university) [K2020-12]; he project of natural science foundation of Jiangsu province [BK20200910]; State Key Laboratory of Automotive Safety and Energy [KFY2227].

Notes on contributors

Ruina Li

Ruina Li: Conceptualization, Methodology, Software.

Dahai Yang

Dahai Yang: Data curation, Writing- Original draft preparation.

Feifan Liu

Feifan Liu: Visualization, Investigation.

Jialong Zhu

Jialong Zhu: Supervision.

Quan Hu

Quan Hu: Software, Validation.