Structure and Formation Mechanism of Methane Explosion Soot

Area of Science:

• Combustion science
• Materials science
• Chemical engineering

Background:

• Gas explosions generate a bright spot phenomenon attributed to highly radiative soot particles.
• Understanding soot formation is crucial for mitigating explosion hazards and analyzing combustion processes.

Purpose of the Study:

• To numerically simulate the formation mechanism of soot and precursor polycyclic aromatic hydrocarbons (PAHs) in methane explosions.
• To experimentally characterize the physical structure and pore distribution of soot generated during methane-air premixed gas explosions.

Main Methods:

• Numerical simulation of methane explosion soot and precursor PAH formation using CHEMKIN-PRO.
• Experimental collection and analysis of soot from 8% CH4-air premixed gas explosions.
• Characterization using low-pressure nitrogen gas adsorption (LP-N2GA), scanning electron microscopy (SEM), and transmission electron microscopy (TEM).

Main Results:

• C2 and C3 species significantly influence early-stage PAH formation during methane explosions.
• LP-N2GA and SEM revealed wedge-shaped pores and well-developed surface porosity in soot particles, some exhibiting melt sintering.
• TEM analysis showed chain-branched soot aggregates (majority ~100 nm) with internal graphite-like lattice stripes.

Conclusions:

• The study elucidates the role of specific carbon species in PAH formation during gas explosions.
• Detailed characterization of methane explosion soot provides insights into its radiative properties and structural morphology.
• Findings lay the groundwork for advanced analysis of soot formation mechanisms in explosive combustion events.