Pyrolysis and oxidation of methyl acetate in a shock tube: A multi-species time-history study.

High-temperature methyl acetate (MA) pyrolysis and oxidation were studied behind reflected shock waves using laser-absorption species time-history measurements of CO, CO 2 , OH and H 2 O. The shock tube experiments with very dilute fuel mixtures covered a temperature range of 1401–1605 K for MA pyrolysis (0.2% MA/Ar) and 1423–1674 K for MA oxidation (0.4% O 2 , ϕ = 1), and pressures around 1.5 atm. The dominant sensitivity of CO 2 concentration to MA unimolecular decomposition reactions enabled accurate determination of the rate coefficient and dissociation branching ratio by monitoring the CO 2 time-history during MA pyrolysis. A recent kinetic mechanism developed by Yang et al. [13] originally for interpreting flow reactor and low-pressure flame data was adopted to simulate and compare with the current shock tube data. The measured CO and CO 2 time-histories during MA pyrolysis were both well-predicted by the modified Yang et al. [13] mechanism. A relatively complete description of MA oxidation behavior was given by measuring CO, CO 2 , OH and H 2 O time-histories at the same temperature and pressure (1480 K, 1.5 atm). A unique two-stage CO 2 formation during MA oxidation was clearly observed in the measured CO 2 time-histories over the entire temperature range, with the rapid pre-ignition CO 2 formation analyzed to be associated with the initial MA dissociation. Despite the overprediction of MA ignition delay times by 18–40% between 1623 and 1423 K, the kinetic model successfully captures the plateau levels and the peak values of all the measured species profiles, as well as simulates the characteristic two-stage formation of CO 2 observed experimentally. [ABSTRACT FROM AUTHOR]