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Soot structure and reactivity analysis by Raman microspectroscopy, temperature-programmed oxidation, and
Markus Knauer1, Manfred E Schuster, Dangsheng Su
1Technische Universität München, Institute of Hydrochemistry, Chair for Analytical Chemistry, Marchioninistr. 17, D-81377 Munich, Germany.
The Journal of Physical Chemistry. A
|November 11, 2009
Summary
This study reveals that spark discharge soot (GfG) exhibits higher disorder and reactivity compared to diesel engine soot (EURO VI and IV). Structural analysis correlates with oxidation behavior, highlighting GfG soot as the most reactive.
Area of Science:
- Materials Science
- Combustion Science
- Analytical Chemistry
Background:
- Soot's structure-reactivity relationship is crucial for understanding combustion processes and emissions.
- Characterizing different soot types, like diesel and spark discharge soot, is essential for emission control strategies.
Purpose of the Study:
- To comprehensively investigate the relationship between the structure and reactivity of various soot types.
- To compare the structural properties and oxidation behavior of spark discharge soot (GfG) and heavy-duty diesel engine soot (EURO VI and IV) with graphite powder.
Main Methods:
- Combined Raman microspectroscopy (RM), temperature-programmed oxidation (TPO), high-resolution transmission electron microscopy (HRTEM), and electron energy loss spectroscopy (EELS).
- Analyzed soot structure using Raman spectral parameters and the dispersive character of the D mode.
- Assessed reactivity through TPO experiments at increasing temperatures.
Main Results:
- GfG soot showed higher structural disorder and more molecular carbon compared to EURO VI and IV diesel soot.
- Structural ordering decreased from graphite powder to EURO IV/VI soot to GfG soot, confirmed by HRTEM and EELS.
- TPO revealed GfG soot as the most reactive, while EURO IV and VI soot exhibited moderate reactivity.
Conclusions:
- Raman, HRTEM, and EELS analyses consistently demonstrate that GfG soot possesses a more disordered structure than diesel soot.
- The structural differences directly correlate with the observed oxidation reactivity, with GfG soot being significantly more reactive.
- Findings provide critical insights into soot formation and oxidation mechanisms, relevant for emission control and material design.
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