A theoretical analysis of propargyl oxidation by the hydroperoxyl radical

The kinetics of the C3H3 + HO2 reaction system were investigated theoretically using high-level quantum chemical methods combined with statistical rate theory. The potential energy surface (PES) was explored to identify intermediates and transition states using reactive molecular dynamics with ChemTraYzer-TAD. The resulting thermochemical data and energy barriers for products P0 to P13 were used in RRKM/master equation calculations to determine the temperature-and pressure-dependent rate constants suitable for incorporation into chemical kinetic models. Implications for chemical kinetic model predictions and future model development were assessed by representative jet-stirred reactor simulations of stoichiometric propyne/air mixtures at 10 atm and 800-1200 K. These simulations show that the widely employed allyl + HO2 analogy overestimates propargyl consumption. In the jet-stirred reactor case considered here, replacing the analogy-based treatment with the theory-based update reduces the contribution of C3H3 + HO2 reactions to the overall consumption of C3H3 from up to 26 % to no more than 15 %. The corresponding changes in benzene predictions are visible, but remain within the experimental uncertainty. Based on these findings, a compact reduced three-reaction submodel is proposed for future chemical kinetic model development.