Ozone-assisted Low-Temperature Oxidation of Methane and Ethane

Acetone is an important intermediate, blend stock and fuel tracer in combustion, but the low-temperature oxidation chemistry of acetone has rarely been understood. This paper studied the ozone-assisted low-temperature oxidation of acetone in an atmospheric jet-stirred reactor (JSR) from 335 to 790 K. Various critical intermediates, such as hydrogen peroxide, methyl hydroperoxide, methylglyoxal, hydroxyacetone, acetonyl hydroperoxide, acetic acid and ketene, were measured by synchrotron vacuum ultraviolet photoionization mass spectrometry (SVUV-PIMS). A kinetic model was also developed to reasonably predict the fuel reactivity and the formation of most intermediates. The kinetic analyses reveal that fuel consumption is initiated by H-atom abstraction reactions to generate CH3CO C(center dot)H2, the consumption of this fuel radical is dominated by the bimolecular reactions with H O(center dot)2, CH3 O(center dot)2 and O2, and finally converted to CH3COCH2 O-center dot. Specifically, the reaction of CH3CO C(center dot)H2 with H O(center dot)2 contributes to (OH)-H-center dot formation and accelerates fuel consumption during this process. The subsequent decomposition of CH3COCH2 O-center dot leads to CH3 (CO)-O-center dot and CH2O, which serve as the essential intermediates during acetone low-temperature oxidation. This work provides new insights into acetone oxidation and valuable data for evaluating ketone kinetic models.