Insights into the combustion mechanisms of turpentine oil based on ReaxFF molecular dynamics simulations

To gain insights into the combustion mechanism of turpentine oil, the oxidation reaction of turpentine was investigated using ReaxFF reactive molecular dynamics simulations. The results revealed that the decomposition of camphene, a component of turpentine, was significantly slow due to the presence of bridged rings in the molecular structure. The oxidation of camphene requires the destruction of six-membered and five-membered rings in sequence. Different oxygen concentrations influenced the initial reactions of turpentine oil. In oxygen-rich conditions, O radicals primarily attacked the C[dbnd]C bonds of turpentine, resulting in the formation of an epoxy structure, C-O-C. In oxygen-poor environments, the thermal decomposition of turpentine is primarily associated with reactions involving C–C bonds. In oxidation, free radicals such as OH, HO₂, and H played a significant role in accelerating the reaction rate, with OH exerting the most substantial influence on the reaction involving turpentine oil. The oxidation products of turpentine (C₁₀H₁₆O₂ and C₁₀H₁₅O) were unstable at high temperatures and decomposed to yield the earliest intermediate, acetone (C₃H₆O), with the dehydrogenation reaction mainly assisted by OH radicals. The formation and consumption of intermediate ketene were closely linked to C2 compounds. Furthermore, almost all formaldehyde was consumed by the free radical OH. The activation energy value of α-pinene is 80.68 kJ/mol, aligns well with the experimentally estimated activation energy (81.3 ± 3.1 kJ/mol). This study elucidates the intricate effects of environmental variations on the oxidation process of turpentine oil, providing crucial atomic-level insights for designing environmentally friendly fuels.