The fluorine atom initiated oxidation of CF3CFH2 (HFC-134a) studied by FTIR spectroscopy

✍ Scribed by Alam S. Hasson; Christopher M. Moore; Ian W. M. Smith

• Publisher: John Wiley and Sons
• Year: 1998
• Tongue: English
• Weight: 197 KB
• Volume: 30
• Category: Article
• ISSN: 0538-8066
• DOI: 10.1002/(sici)1097-4601(1998)30:8<541::aid-kin3>3.0.co;2-s

✦ Synopsis

Experiments have been carried out on the oxidation of CF 3 CFH 2 (HFC-134a). Reaction was initiated by continuous photolysis of F 2 in the near-ultraviolet. The F atoms produced abstracted a hydrogen atom from CF 3 CFH 2 initiating oxidation in gas mixtures containing O 2 and made up to a total pressure of with N 2 . Product yields were measured 700 torr using Fourier-transform infrared (FTIR) spectroscopy. Experiments were performed with several different partial pressures of O 2 present, and at three temperatures; 298, 323, and 357 K. The major products were HC(O)F, CF 3 C(O)F, and CF 3 O 3 CF 3 , consistent with H atom abstraction by O 2 and CC bond scission being the dominant loss processes for CF 3 CFHO radicals:

The following expression was derived for the ratio of rate constants for these reactions:

The main fate of the CF 3 radicals was formation of CF 3 O 3 CF 3 and small amounts of CF 3 OH were detected. The results of the present experiments in which F atoms were used to initiate reaction are in good agreement with those of previous studies in which Cl atoms were employed to initiate the oxidation of HFC-134a.