Single-Pulse Shock-Tube Studies of the Pyrolysis of Fluorocarbons and of the Oxidation of Perfluoroethylene

The gas phase pyrolysis and oxidation of several low molecular weight fluorocarbons were investigated in single-pulse shock tubes, using vapor phase chromatography and mass spectral analyses to establish the nature and the relative amounts of all the products generated as a function of the reflected shock temperature and the initial composition. Dwell times were approximately 1 msec and quenched rates were about 1°/μsec. Shocks were run in mixtures ranging from 0.5-3% of fluorocarbons in argon. Plots of product distributions as a function of reflected shock temperatures have been prepared for perfluorocyclobutane, butadiene, cyclopropane, propene, and ethylene. Several equilibrium constants for the interconversions of fluorocarbons were evaluated at a function of temperature, a mechanism of the pyrolysis reactions δ developed, and the corresponding rate constants estimated. Mixtures of perfluoro-ethylene in oxygen, highly diluted in argon, were shock-heated for periods of about 1.3 msec to temperatures in the range 1200-2000°K. The major products were F2CO, CO, CF4, C2F6 and very small amounts of C3F6 and CO2. On the basis of the product distribution analyses a plausible mechanism for the oxidation reaction has been developed.