Soot Formation and Growth in Toluene/Ethylene Combustion Catalyzed by Ruthenium Acetylacetonate

ABSTRACT

Ruthenium-based compounds are efficient catalysts to enhance combustion performance and suppress soot emission. However, systematic mechanism and in-situ research on reducing soot are rarely addressed. In this study, ruthenium acetylacetonate (Ru(C₅H₇O₂)₃, Ru(acac)₃) was utilized as the catalyst precursor in different concentration conditions to investigate its impacts on the size, volume, and morphology of the soot particles in the ethylene flames with central toluene injection. The soot particles were detected by in-situ small-angle X-ray scattering (SAXS) and ex-situ transmission electron microscopy (TEM). This study confirms that Ru(acac)₃ can suppress the surface growth for the primary soot particles, but no significant change of the morphology has been discovered for the aggregates. Compared with the undoped flame, the volume of the soot particles in the Ru(acac)₃-doped flames is lower and the particle size is smaller, indicating a valid inhibition effect of Ru(acac)₃ on the soot emission by affecting its surface growth and oxidation process. Despite the remarkable distinction between the undoped and doped flames, no obvious difference is found between the flames with different catalyst concentrations.

KEYWORDS:

• Soot
• catalyst
• ruthenium acetylacetonate
• surface growth
• oxidation
• in-situ small angle X-ray scattering

Acknowledgment

The authors gratefully acknowledge the National Natural Science Foundation of China (the grant number U2032119, 91641125 and 71690245) for their financial support. We also thank for the “IRENA” micro package provided by Dr. Jan Ilavsky for data fitting. Besides, we would like to acknowledge Yuchen Zhu, a PhD student in University of Science and Technology Beijing, for his advice in TEM analysis. This research was performed at the APS, a U.S. Department of Energy (DOE) Office of Science User Facility under Contract No. DE-AC02-06CH11357.

Disclosure statement

The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.

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Additional information

Funding

This work was supported by the National Natural Science Foundation of China [71690245,91641125,U2032119].