Oxidation study of small hydrocarbons at elevated pressure. Part I: Neat 1,3-butadiene

To study the formation pathways of aromatic compounds in the oxidation process of soot precursors under different equivalent ratios (& phi;), two parts of work were carried out. The present work was the part I: the oxidation of 1,3-butadiene (1,3-C4H6) was studied in a jet-stirred reactor at high-pressure (12 atm) within a temperature range covering 575-1075 K, at fuel equivalence ratios (& phi;) of 0.5 and 3.0. Part II focused on the study of oxidation of a two-compound mixture of acetylene and 1,3-butadiene. Mole fraction profiles of 20 species obtained by GC/MS analysis were identified and quantified. The measured species profiles serve as a data base for the further development of a detailed chemical kinetic reac-tion mechanism AramcoMech 3.0 generated by Zhou et al. previously for describing the ignition delay time and laminar flame speed of 1,3-butadien. The resulting reaction mechanism comprising 625 species and 3188 reactions was found to be able to describe credibly the experimental species profiles. Rate-of-production (ROP) analysis reveals that addition reactions of H and OH radicals to 1,3-C4H6 are the major channels governing 1,3-C4H6 consumption under both fuel-lean and fuel-rich conditions. Acety-lene (C2H2), vinyl acetylene (C4H4), and propargyl radicals (C3H3) are playing important roles within the formation of mono-aromatics. Here, benzene is mainly formed via the C2 + C4 pathways instead of the C1 + C5 routes. Furthermore, C3H3 radicals were found to play a key role within C6H5CH3 formation. Naphthalene are formed by the reactions of C6H6 and 1,3-C4H6 or C4H5 -N/I radicals. These results will enrich the understanding of elevated pressure chemistry of 1,3-C4H6 and facilitate to further model de-velopment and validation focusing on a more detailed description of the formation network of aromatic compounds.& COPY; 2023 The Combustion Institute. Published by Elsevier Inc. All rights reserved.