Structure of premixed flames of propylene oxide: Molecular beam mass spectrometric study and numerical simulation

The knowledge of the combustion chemistry of oxygenated fuels is essential for the development of detailed kinetic mechanisms suitable for the combustion processes involving biofuels. Moreover, epoxidized olefins, are increasingly used as chemical intermediates or as bulk chemicals. Nevertheless, a dearth of data for their reactivity in the oxidative environment can be observed in the current literature. This study reports the experimental and the model characterization of the flame structure of propylene oxide at stoichiometric and fuel-rich conditions at atmospheric pressure. To this aim, the species mole fractions in three premixed flames stabilized on a flat-flame burner have been quantitatively measured by using the flame sampling molecular beam mass spectrometry. Three chemical kinetic mechanisms retrieved from the current literature involving propylene oxide chemistry have been validated against the novel experimental data. In general, the predictions appeared to be in satisfactory agreement with measurements except for acetaldehyde and ketene. The rate of production analysis in the flame has shown that the discrepancies observed for these species are related basically to the incorrect ratio between the rates of primary reaction pathways of propylene oxide destruction.