HO2 formation from the OH + benzene reaction in the presence of O2

Nehr, S.; Wahner, A.; Hofzumahaus, A.; Fuchs, H.; Bohn, B.

doi:10.1039/c1cp20334g

Journal Article

PreJuSER-15752

HO2 formation from the OH + benzene reaction in the presence of O2

Nehr, S.FZJ* ; Bohn, B.FZJ* ; Fuchs, H.FZJ* ; Hofzumahaus, A.FZJ* ; Wahner, A.FZJ*

2011
RSC Publ. Cambridge

Physical Chemistry Chemical Physics 13, 10699-10708 (2011) [10.1039/c1cp20334g]

This record in other databases:

Please use a persistent id in citations: http://hdl.handle.net/2128/7303 doi:10.1039/C1CP20334G

Abstract: In this study we investigated the secondary formation of HO(2) following the benzene + OH reaction in N(2) with variable O(2) content at atmospheric pressure and room temperature in the absence of NO. After pulsed formation of OH, HO(x) (= OH + HO(2)) and OH decay curves were measured by means of a laser-induced fluorescence technique (LIF). In synthetic air the total HO(2) yield was determined to be 0.69 ± 0.10 by comparison to results obtained with CO as a reference compound. HO(2) is expected to be a direct product of the reaction of the intermediately formed OH-benzene adduct with O(2). The HO(2) yield is slightly greater than the currently recommended yield of the proposed HO(2) co-product phenol (∼53%). This hints towards other, minor HO(2) forming channels in the absence of NO, e.g. the formation of epoxide species that was proposed in the literature. For other test compounds upper limits of HO(2) yields of 0.10 (isoprene) and 0.05 (cyclohexane) were obtained, respectively. In further experiments at low O(2) concentrations (0.06-0.14% in N(2)) rate constants of (2.4 ± 1.1) × 10(-16) cm(3) s(-1) and (5.6 ± 1.1) × 10(-12) cm(3) s(-1) were estimated for the OH-benzene adduct reactions with O(2) and O(3), respectively. The rate constant of the unimolecular dissociation of the adduct back to benzene + OH was determined to be (3.9 ± 1.3) s(-1). The HO(2) yield at low O(2) was similar to that found in synthetic air, independent of O(2) and O(3) concentrations indicating comparable HO(2) yields for the adduct + O(2) and adduct + O(3) reactions.

Keyword(s): J

Classification:

Note: The authors thank F. Rohrer, F. Holland, S. Lou and M. Bachner for useful discussions and technical support. S. Nehr thanks the Deutsche Forschungsgemeinschaft for PhD studentship funding under grant BO 1580/3-1.

Contributing Institute(s):