Shock tube measurements of specific reaction rates in the branched chain CH 4−CO−O 2 system

Abstract

Rate constants of two elementary bimolecular reactions involved in the oxidation of methane have been determined by monitoring the exponential growth of CO flame band emission behind incident shocks in three suitably chosen gas mixtures. Results are as follows: O+CH4→CH3+OH, k7=1.9×1014exp(−5900/T) cm3 mole−1sec−1 (1300°–2000°K) and CH2+O2→CH3O+O, k10=2.4×1013exp(−14500/T) (1200°–1800°K) assuming CH3O+M→CH2O+H+M. [If it is assumed that CH3O+CO→CO2+CH3, then k10=5.9×1013exp(−14500/T).] The data do not support a mechanism which invokes the four center process CH3+O2→CH2O+OH for the reaction of methyl with oxygen.