PREFLAME OXIDATION CHARACTERISTICS OF METHANOL

The low-temperature slow oxidation of methanol was examined experimentally in a constant volume stirred reactor. Initial temperatures ranged from approximately 650 to 700 K. Initial pressures of 700 Torr and below were examined and the equivalence ratio was varied between 0.5 and 1.5. Temperature and pressure histories were obtained for methanol reacting in air and oxygen. Global indicators of reaction rate, reactivity, and autoignition tendency were derived from these data. The relationship among these indicators and the effects on these indicators of initial temperature, initial pressure, and fuel/oxidizer mixture ratio were examined. In general, it was found that the overall reaction rate increased with increasing temperature, pressure, and equivalence ratio. Correlations were developed from the data which represent these effects over the range of conditions examined. In addition, chemical measurements were made using gas chromatography to examine the reactant, stable intermediate, and product species histories and to gain insight into the oxidation mechanism at the conditions studied. The results are in agreement with an earlier mechanism and indicate that the basic path of the low-temperature oxidation of methanol proceeds via CH3OH --> CH2OH --> CH2O --> CHO --> CO (--> CO2).