Coal Spontaneous Oxidation Mechanism of Low-Molecular Compounds: Pentanol

Coal spontaneous combustion (CSC) remains a major hazard in coal mining. Research on CSC has largely focused on macromolecular structures, while the behavior of low-molecular-weight compounds remains unclear. Using B3LYP/6-311G density functional theory, this study systematically reveals thirteen microscopic reaction pathways, active sites, and the energy barrier order of pentanol during coal spontaneous combustion. The oxidation proceeds via thirteen multi-step pathways involving bond breaking and formation, with the dominant reaction being oxygen attack on the -CH2OH group to produce pentanal (CH3CH2CH2CH2CHO) and water as the main products. The priority order of thirteen reaction pathways between pentanol and oxygen was established as: Path 6 > Path 3 > Path 8 > Path 5 > Path 4 > Path 1 > Path 11 > Path 10 > Path 9 > Path 12 > Path 7 > Path 2. The results reveal the multi-step bond-breaking and formation mechanism at the molecular level, providing a fundamental theoretical framework for understanding the radical chain oxidation mechanism of low molecular weight compounds in CSC.