Kinetic study of reaction C2H5 + HO2 in a photolysis reactor with time-resolved faraday rotation spectroscopy

Hongtao Zhong, Chao Yan, Chu C. Teng, Guoming Ma, Gerard Wysocki, Yiguang Ju

Research output: Contribution to journalArticlepeer-review

Abstract

The rate constant and branching ratios of ethyl reaction with hydroperoxyl radical, C2H5 + HO2 (1), a key radical-radical reaction for intermediate temperature combustion chemistry, were measured in situ for the first time in a photolysis Herriott cell by using mid-IR Faraday rotation spectroscopy (FRS) and UV-IR direct absorption spectroscopy (DAS). The microsecond time-resolved diagnostic technique in this work enabled the direct rate measurements of the target reaction at 40 and 80 mbar and reduced the experimental uncertainty considerably. C2H5 and HO2 radicals were generated by the photolysis of (COCl)2/C2H5I/CH3OH/O2/He mixture at 266 nm. By direct measurements of the transient profiles of C2H5, HO2 and OH concentrations, the overall rate constant for this reaction at 297 K was determined as k1(40 mbar) = (3.8 ± 0.8) × 11 cm3 molecule-1 s-1 and k1(80 mbar) = (4.1 ± 1.0) × 10-1 cm3 molecule-1 s-1. The direct observation of hydroxyl radical (OH) indicated that OH formation channel was the major channel with a branching ratio of 0.8 ± 0.1.

Original languageEnglish (US)
JournalProceedings of the Combustion Institute
DOIs
StateAccepted/In press - 2020

All Science Journal Classification (ASJC) codes

  • Chemical Engineering(all)
  • Mechanical Engineering
  • Physical and Theoretical Chemistry

Keywords

  • Chemical kinetics
  • Faraday rotation spectroscopy
  • Hydroperoxyl radical
  • Radical-radical reaction
  • Rate constant

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