Elucidating the mechanism of 1,3-butadiene oxidation with O2: A DFT study

1,3-Butadiene (1,3-C4H6) is a ubiquitous pollutant produced during the combustion of hydrocarbon fuels in engine cylinders. In this study, we delved into the potential energy surface (PES) and rate constant of 1,3-C4H6 employing the density theory (DFT) method and transition state theory (TST). This study comprehensively clarifies the process of O2 oxidation 1,3-C4H6 and its significance on the prediction of combustion dynamic models. Our research reveals that the addition of O2 to the terminal carbon atom of 1,3-C4H6 is the dominant path for addition reactions, leading to the formation of peroxyl radicals. Subsequently, these reactions predominantly yield acrolein and aldehyde groups. Moreover, our data indicates a barrierless and exothermic path for the generation of peroxyl radicals by the O2 addition to the C4H5 radical site. The energy barrier for the dominant path, 1,3-C4H6+H → iC4H5+H2, has been calculated to be 57.6 kJ/mol with a rate constant of 7.89×1010 cm3 mol−1 s−1. This study integrates the kinetic and thermochemical data derived from our targeted reaction system into the updated AramcoMech 3.0. An in-depth analysis reveals the capability of this mechanism to simulate combustion characteristics of 1,3-C4H6, emphasizing its temperature-dependent species profiles. Comparatively, the performance evaluation of the proposed 1,3-C4H6 kinetic mechanism demonstrates its improvement over its predecessor, showing good agreement with experimental results.