Exploring reaction mechanism and kinetics of acetone pyrolysis and combustion in O2/H2O/CO2 environments via ReaxFF MD simulations

Abstract

Acetone is a promising bio-derived fuel, but its high-temperature pyrolysis and combustion mechanisms are not yet fully understood. Atomic-level insights are essential for achieving clean combustion and guiding advanced fuel design. In this study, reactive molecular dynamics (ReaxFF MD) simulations were employed to investigate the detailed reaction behavior of acetone, with the force field accuracy validated through density functional theory (DFT) calculations. The pyrolysis process was found to proceed through three stages: initial molecular decomposition, gas transfer, and soot formation. Soot inception and growth involve ring formation, hydrogen abstraction acetylene addition (HACA) reactions, and molecular coagulation. During combustion, oxidation proceeds primarily through methyl radical pathways, ultimately yielding CO and CO 2 . Increasing oxygen content enhances the production of H 2 O and CO 2 while suppressing H 2 and key soot precursors. For intermediate species, higher oxygen levels lead to increased formation of oxygenated compounds and reduced hydrocarbon fragments. The apparent activation energy for combustion aligns well with experimental ignition delay data. The presence of H 2 O or CO 2 impurities significantly alters reaction frequencies and modifies dominant reaction channels. Soot inhibition occurs via distinct mechanisms: H 2 O participates in reactions with carbon-containing radicals to produce CO or CO 2 , while CO 2 reacts with carbon-containing radicals to form two CO molecules. H 2 O exhibits a stronger soot inhibition effect and also enhances combustion, whereas CO 2 slightly suppresses it. These findings offer mechanistic insights into acetone reactivity and support the development of cleaner biofuel technologies. • The mechanism and kinetics of acetone pyrolysis and oxidation are investigated. • Gas production and soot formation during acetone pyrolysis and combustion are explored. • Soot inception involving ring formation, HACA, and coagulation is observed via ReaxFF MD. • The effects of EGR gases on combustion behavior and soot suppression are analyzed. • The apparent activation energy for acetone combustion aligns well with experimental data.

Topics & Concepts