Detailed Chemical Kinetic Modeling of Cyclohexane Oxidation†

A detailed chemical kinetic mechanism has been developed and used to study the oxidation of cyclohexane
at both low and high temperatures. Rules for reaction rate constants are developed for the low-temperature
combustion of cyclohexane. These rules can be used for in chemical kinetic mechanisms for other cycloalkanes.
Because cyclohexane produces only one type of cyclohexyl radical, much of the low-temperature chemistry
of cyclohexane is described in terms of one potential energy diagram showing the reaction of cyclohexyl
radical with O2 through five-, six-, and seven-membered-ring transition states. The direct elimination of
cyclohexene and HO2 from RO2 is included in the treatment using a modified rate constant of Cavallotti et
al. (Proc. Combust. Inst. 2007, 31, 201). Published and unpublished data from the Lille rapid compression
machine, as well as jet-stirred reactor data, are used to validate the mechanism. The effect of heat loss is
included in the simulations, an improvement on previous studies on cyclohexane. Calculations indicated that
the production of 1,2-epoxycyclohexane observed in the experiments cannot be simulated according to the
current understanding of low-temperature chemistry. Possible “alternative” H-atom isomerizations leading to
different products from the parent O2QOOH radical were included in the low-temperature chemical kinetic
mechanism and were found to play a significant role.