Reactive Molecular Dynamics Study on Soot Formation Mechanism in Iron-Doped Ethylene Combustion
- 1Maanshan General Hospital of Ranger-Duree Healthcare, Ma’anshan 243000, China
- 2Engineering Research Center of Biofilm Water Purification and Utilization, Technology of Ministry of Education, Anhui University of Technology, Ma’anshan 243032, China
- 3School of Mechanical and Electrical Engineering, Tongling University, Tongling 244061, China
Abstract
Iron (Fe) powder is a promising zero-carbon energy carrier, and its co-combustion with hydrocarbon fuels offers a transitional route toward decarbonized power generation. Fe has nevertheless been experimentally found to aggravate early soot nucleation and growth in flames while reducing engine-out soot emissions, and the atomic-scale mechanism by which Fe regulates polycyclic aromatic hydrocarbons (PAHs) and soot formation remains unresolved. To address this gap, reactive molecular dynamics (ReaxFF MD) was employed to investigate PAHs and soot formation during the combustion of ethylene (C2H4) doped with Fe, across three reaction temperatures (2000, 2500, and 3000 K) and three Fe loading levels (0, 6, and 12 Fe atoms, corresponding to Fe/C atomic ratios of 0, 2.5%, and 5.0%). The CHOFe-2012.ff reactive force field was selected for the Fe-containing simulations because it reproduces the experimentally validated Fe-free ethylene combustion benchmarks most closely among the force fields compared, while also describing Fe-C and Fe-O interactions. At 20 ns and 3000 K, the largest soot cluster detected contains 191 carbon atoms with a C/H ratio of 7.07, favoring the formation of highly graphitized mature soot. In contrast, under 2000 K, the corresponding largest cluster possesses only 77 carbon atoms and exhibits a C/H ratio of 3.35, yielding only loosely structured young soot. It should be noted that these descriptors characterize the most evolved cluster identified in each simulation rather than the entire soot population. Within the tested conditions, Fe doping is found to promote soot formation: both the carbon-atom number and the C/H ratio of the largest soot cluster increase markedly, and this effect strengthens with increasing Fe loading. Notably, the O2 level varied by less than 2.2% across the Fe-loading series, and these descriptors refer to the largest detected cluster; within the present simulation framework, the promotion is therefore attributed predominantly to the chemical effect of Fe doping. The reaction path analysis reveals that Fe atoms form Fe-containing small carbon nuclei by combining with C2H4, dehydrogenation and addition reactions, and then gradually develop into mature soot particles through coalescence, surface growth and graphitization, indicating that Fe participates in the nucleation stage of soot formation under the tested conditions. This study provides a molecular-level understanding of the microscopic mechanism of Fe–soot interactions, offering mechanistic insight at the molecular scale that may inform the optimization of Fe-hydrocarbon dual-fuel systems and the mitigation of Fe-induced soot formation.
Related
- Molecular Dynamics Study on Combustion Characteristics and Soot Formation Reactions of C4 Isomers Blended with NH3
- Interfacial Mechanisms of Reactive Dye Adsorption on a Waste-Cotton Derived PVA/TiO2/Cellulose Biofilm: A Molecular Dynamics and Physics-Informed Predictive Framework
- Kinetic Mechanism Development and Pollutant Chemistry in NH3/H2/CH4 Combustion
- Crystallinity-Regulated Hydration, Molecular Mobility, and Mechanical Softening of Poly(ether ether ketone): A Reactive Molecular Dynamics Study
- Reactive molecular dynamics simulations of atenolol first steps degradation by 9CL6 ammonia monooxygenase
BibTeX
@article{wang2026reactive,
title = {{Reactive Molecular Dynamics Study on Soot Formation Mechanism in Iron-Doped Ethylene Combustion}},
author = {Yang Wang and Yiju Zhao and Junjie Lu and Yuan Zhu and Zhenhui Zhang and Lumin Chen and Mingyan Gu},
journal = {Molecules},
year = {2026},
month = oct,
doi = {10.3390/molecules31213889},
url = {https://www.mdpi.com/1420-3049/31/21/3889},
note = {CC BY 4.0},
}
RIS
TY - JOUR
TI - Reactive Molecular Dynamics Study on Soot Formation Mechanism in Iron-Doped Ethylene Combustion
AU - Yang Wang
AU - Yiju Zhao
AU - Junjie Lu
AU - Yuan Zhu
AU - Zhenhui Zhang
AU - Lumin Chen
AU - Mingyan Gu
PY - 2026
DA - 2026/10/28
JO - Molecules
DO - 10.3390/molecules31213889
UR - https://www.mdpi.com/1420-3049/31/21/3889
AB - Iron (Fe) powder is a promising zero-carbon energy carrier, and its co-combustion with hydrocarbon fuels offers a transitional route toward decarbonized power generation. Fe has nevertheless been experimentally found to aggravate early soot nucleation and growth in flames while reducing engine-out soot emissions, and the atomic-scale mechanism by which Fe regulates polycyclic aromatic hydrocarbons (PAHs) and soot formation remains unresolved. To address this gap, reactive molecular dynamics (ReaxFF MD) was employed to investigate PAHs and soot formation during the combustion of ethylene (C2H4) doped with Fe, across three reaction temperatures (2000, 2500, and 3000 K) and three Fe loading levels (0, 6, and 12 Fe atoms, corresponding to Fe/C atomic ratios of 0, 2.5%, and 5.0%). The CHOFe-2012.ff reactive force field was selected for the Fe-containing simulations because it reproduces the experimentally validated Fe-free ethylene combustion benchmarks most closely among the force fields compared, while also describing Fe-C and Fe-O interactions. At 20 ns and 3000 K, the largest soot cluster detected contains 191 carbon atoms with a C/H ratio of 7.07, favoring the formation of highly graphitized mature soot. In contrast, under 2000 K, the corresponding largest cluster possesses only 77 carbon atoms and exhibits a C/H ratio of 3.35, yielding only loosely structured young soot. It should be noted that these descriptors characterize the most evolved cluster identified in each simulation rather than the entire soot population. Within the tested conditions, Fe doping is found to promote soot formation: both the carbon-atom number and the C/H ratio of the largest soot cluster increase markedly, and this effect strengthens with increasing Fe loading. Notably, the O2 level varied by less than 2.2% across the Fe-loading series, and these descriptors refer to the largest detected cluster; within the present simulation framework, the promotion is therefore attributed predominantly to the chemical effect of Fe doping. The reaction path analysis reveals that Fe atoms form Fe-containing small carbon nuclei by combining with C2H4, dehydrogenation and addition reactions, and then gradually develop into mature soot particles through coalescence, surface growth and graphitization, indicating that Fe participates in the nucleation stage of soot formation under the tested conditions. This study provides a molecular-level understanding of the microscopic mechanism of Fe–soot interactions, offering mechanistic insight at the molecular scale that may inform the optimization of Fe-hydrocarbon dual-fuel systems and the mitigation of Fe-induced soot formation.
SN - 1420-3049
ER -