Measuring hydroperoxide chain-branching agents during n-pentane low-temperature oxidation
Westmoreland, Phillip R.
KAUST DepartmentClean Combustion Research Center
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AbstractThe reactions of chain-branching agents, such as HO and hydroperoxides, have a decisive role in the occurrence of autoignition. The formation of these agents has been investigated in an atmospheric-pressure jet-stirred reactor during the low-temperature oxidation of n-pentane (initial fuel mole fraction of 0.01, residence time of 2s) using three different diagnostics: time-of-flight mass spectrometry combined with tunable synchrotron photoionization, time-of-flight mass spectrometry combined with laser photoionization, and cw-cavity ring-down spectroscopy. These three diagnostics enable a combined analysis of HO, C-C, and C alkylhydroperoxides, C-C alkenylhydroperoxides, and C alkylhydroperoxides including a carbonyl function (ketohydroperoxides). Results using both types of mass spectrometry are compared for the stoichiometric mixture. Formation data are presented at equivalence ratios from 0.5 to 2 for these peroxides and of two oxygenated products, ketene and pentanediones, which are not usually analyzed during jet-stirred reactor oxidation. The formation of alkenylhydroperoxides during alkane oxidation is followed for the first time. A recently developed model of n-pentane oxidation aids discussion of the kinetics of these products and of proposed pathways for C-C alkenylhydroperoxides and the pentanediones.
CitationRodriguez A, Herbinet O, Wang Z, Qi F, Fittschen C, et al. (2016) Measuring hydroperoxide chain-branching agents during n-pentane low-temperature oxidation. Proceedings of the Combustion Institute. Available: http://dx.doi.org/10.1016/j.proci.2016.05.044.
SponsorsThis work was supported by European Commission (“Clean ICE” ERC Advanced Research Grant) and by COST Actions CM0901 and 1404. The authors thank John Bugler and Henry Curran for providing their mechanism before the submission of the related paper .