Study on combustion reaction products and free radicals of aliphatic hydrocarbon functional groups in coal based on ML potential MD

The Gas-phase products generated by aliphatic hydrocarbon functional groups during the spontaneous combustion of coal represent a significant source of environmental pollution. A primary focus of contemporary research is the investigation of their microscopic reaction pathways and the dynamics of free radical transformations. This study examines the combustion and pyrolysis reaction mechanisms of three distinct aliphatic hydrocarbon functional groups utilising the Machine Learning Potential Molecular Dynamics (ML potential MD) method, with validation conducted through thermogravimetric-Fourier transform infrared spectroscopy (TG-FTIR) and in-situ FTIR experiments. The findings suggest that the reactivity of the ‒CH group is the highest, followed by ‒CH₂, while ‒CH₃ exhibits the greatest stability. The ‒CH functional group exhibits the highest tendency for CH₄ produced, the ‒CH₂ group displays the highest tendency for CO₂ produced, and the ‒CH₃ group demonstrates the highest tendency for H₂O and CO produced. The ·O radical plays a pivotal role in promoting combustion in the oxidative combustion of functional groups, while both the ·HO radical and the ·H radical act as key initiators in this process. These findings offer theoretical insights into mitigating carbon emissions from the perspective of functional groups and free radicals.