Kinetics of Decomposition and Isomerization of Methylcyclohexane: Starting Point for Studying Monoalkylated Cyclohexanes Combustion

Monoalkylated cyclohexanes are one of the typical constituents existing in practical fuels, especially in jet fuel. As the first step to study the combustion chemistry of monoalkylated cyclohexanes, the unimolecular reactions of methylcyclohexane (MCH) were investigated by combined theoretical calculations and experimental measurements for MCH pyrolysis and flames in the present work. The temperature- and pressure-dependent kinetics of unimolecular reactions of MCH including its dissociation and isomerization channels were computed by high-level quantum chemical calculations and Rice-Ramsperger-Kassel-Marcus/master equation simulations, which also reveal the competition relationship between the two channels. The theoretical predictions were examined by the experimental observations including species identification measured by photoionization efficiency spectra. The presented unimolecular reaction mechanism and corresponding temperature- and pressure-dependent rate constants provide a useful reference for further exploring combustion chemistry of cyclohexanes by kinetic modeling.