Determination of the arrhenius parameters for the initiation reaction C3H6+ O2? CH2CHCH2+ HO2

Abstract

Results obtained from studies of t h e oxidation of propene between 400 and 520°C have been used to obtain the first Arrhenius parameters for t h e important chain initiation reaction RH + 0, --+ R + HO,, where RH is a hydrocarbon.A full product analysis in the early stages of reaction has been made for a number of mixtures at 400, 440, 480 and 520°C. It has been shown that hexa-1,5-diene is a major initial product and that its formation in reaction (8) represents the major termination process. By use of measurements of the initial rate of formation of hexa-1,5diene [(/?HDE)O]t so that secondary initiation is negligible, then in the absence of radical branching the simpleValues of k, at a constant temperature obtained from the relationship vary by less than a factor of two over a wide range of mixture composition, and the average values at each temperature give A , = lo9., dm3 mol-' s-' and E, = 162 kJ mol-'.

Experimental study of the kinetic interactions in the low-temperature autoignition of hydrocarbon binary mixtures and a surrogate fuel

“…The kinetic properties of the resulting stabilized allylic-type radicals are not well known. Reversible oxygen addition followed by isomerization and O-O cleavage are postulated [21,22]:…”

“…The formation of a hydroperoxide adduct between an allylic-type radical and HO 2 , as well as its decomposition, is also speculative [21,22,[25][26][27][28]:…”

Theoretical rate coefficients for allyl+HO2 and allyloxy decomposition

“…Stothard & Walker measured the rate coefficient for the reverse reaction, k À1a , C 3 H 6 + 3 O 2 ? allyl + HO 2 [36]. The present thermochemistry was used to calculate the rate coefficient for this reaction, shown in the inset in Fig.…”

Oxidation of small alkenes at high temperature

“…The values for the abstractions of primary allylic H‐atoms are taken from the values proposed for propene by Stothard et al 25 (for bimolecular initiation with O 2 ) and by Tsang 26 (for metatheses); the values for secondary allylic H‐atoms are deduced from those of primary allylic H‐atoms by considering the same A ‐factors and the same differences in activation energies as between primary and secondary alkylic H‐atoms 1. The values for vinylic H‐atoms are taken from the values proposed for propene by Dagaut et al 8 (for bimolecular initiation with O 2 ) and by Tsang 26 (for metatheses).…”