FTIR spectroscopic study of the Cl- and Br-atom initiated oxidation of ethene

✍ Scribed by G. Yarwood; N. Peng; H. Niki

• Publisher: John Wiley and Sons
• Year: 1992
• Tongue: English
• Weight: 739 KB
• Volume: 24
• Category: Article
• ISSN: 0538-8066
• DOI: 10.1002/kin.550240406

✦ Synopsis

Abstract

The reaction mechanism of the halogen (Cl and Br)‐atom initiated oxidation of C~2~H~4~ was studied using the long path FTIR spectroscopic method in 700 torr of air at 296 ± 2 K. Among the major halogen‐containing products were XCH~2~CHO, XCH~2~CH~2~OH, and XCH~2~CH~2~OOH (X = Cl or Br) which were shown to be formed via the self‐reaction of the XCH~2~CH~2~OO radicals, i.e., 2XCH~2~CH~2~OO → 2XCH~2~CH~2~O + O~2~; (a) 2XCH~2~CH~2~OO → XCH~2~CHO + XCH~2~CH~2~OH + O~2~ and (b) followed by XCH~2~CH~2~O + O~2~ → XCH~2~CHO + HO~2~ and XCH~2~CH~2~OO + HO~2~ → XCH~2~CH~2~OOH + O~2~. From the observed yields of XCH~2~CHO and XCH~2~CH~2~OH the branching ratios for reactions (a) and (b) were determined to be k~a~/k~b~ = 1.35 ± 0.07(2σ) for both X = Cl and Br. In addition, the O~2~‐dependence of the rate constant for the Br + C~2~H~4~ reaction was determined by the relative rate technique as a function of O~2~ partial pressure from 140 to 700 torr at 700 torr total pressure of N~2~/O~2~ diluent. Rate constants for the reactions of Cl‐atoms with Cl‐CH~2~CHO and Br‐atoms with Br‐CH~2~CHO were also determined to be [4.3 ± 0.2(2sigma;)] × 10^−11^ and less than or equal to [1.83 ± 0.11(2σ)] × 10^−13^ cm^3^ molecule^−1^ s^−1^, respectively.