ESR and Mass Spectrometric Studies of Methanol Combustion. II. Correlation between Labile and Stable Chemical Species in Methanol–Oxygen–Argon Flame at Low Pressure

In order to experimentally elucidate the chemical reactions of methanol combustion, the concentration profiles of ten chemical species were determined in stoichiometric CH3OH–O2–Ar flat flame at low pressure, 1.11×104 Pa. The concentrations of three labile intermediates (H, O, and OH) as well as that of stable O2 molecules, were measured by means of the probe-sampling-ESR method. The concentrations of six stable species (CH3OH, CH2O, CO, CO2, H2, and H2O) were measured using a quadrupole mass spectrometer. The rates of the net chemical formation (or decay) of these species were determined by subtracting the effect of diffusion from their observed concentration profiles, and were examined on the basis of the reaction mechanisms previously proposed for methanol combustion. The experimental results were found to be consistent with the oxidation pathway CH3OH→CH2OH→CH2O→CHO→CO→CO2. The results also showed that the reaction CH2OH+O2→CH2O+HO2 is an important pathway for O2 consumption.