On the reactions of peroxy radicals in the slow combustion of methane and ethylene

Abstract

The slow combustion of methane and ethylene has been studied under static conditions in a quartz reactor using the following mixtures: CH 4:O 2 = 1:2 and C 2H 4:O 2 = 1:1. By measuring the consumption of the reagents and the accumulation of radicals, the relation between the rate of the hydrocarbon consumption and the concentrations of free radicals and hydrocarbons has been determined. It has been shown that during the oxidation of methane (at 455°C) two peroxy radicals RO 2 interact, while in the case of ethylene (at 415°C) the peroxy radicals interact with ethylene; in both cases the peroxy radicals are transformed to more active RO radicals, which ensure chain development and lead to the formation of the end products. The rate constants of the interaction of peroxy radicals during methane oxidation (K 2 = 1.02 × 10 −12 cm 3 molecule −1 sec −1) and of peroxy radicals with ethylene during oxidation of the latter when ethylene oxide is formed (K 3 = 0.94 × 10 −16 cm 3 molecule −1 sec −1) has been estimated. The activation energy of the reaction with ethylene has been also estimated and found to be equal to 13,760 ± 800 cal/mole.