Hot β-scission of radicals formed via hydrogen abstraction

Often, the first step of fuel combustion is the formation of fuel radicals. These radicals can be formed via hydrogen abstraction and are typically rovibrationally excited due to the energy release from the reaction. These excitations increase the population at high energies, thus increase the probability for β-scission of the fuel radical. Hot β-scission of such non-thermal radicals can be interpreted as well-skipping reaction from the bimolecular hydrogen abstraction reactants to the dissociation products.In the present study, the impact of non-Boltzmann radical distributions on β-scission kinetics is screened for several hundred fuels. For that purpose, the free energy release between stable stationary points is predicted using group contribution theory. Based on that screening, fuel radicals with potentially pronounced β-scission of rovibrationally excited fuel radicals are picked for more detailed study.Hot β-scission is found to significantly contribute to the CO2 loss reactions of formate radicals formed via hydrogen abstraction. Especially for methyl formate, β-scission of non-thermal radicals is found to dominate over a wide range of temperature and pressure. This reveals the need for including the origin of reactants of β-scission reactions.