화학공학소재연구정보센터
Journal of Physical Chemistry A, Vol.103, No.30, 5967-5977, 1999
Shock tube study of the oxidation of C3F6 by N2O
The kinetics of the high-temperature oxidation of C3F6 by O(P-3) have been studied by experiment, using a single-pulse shock tube, and by kinetic modeling. The O atoms were generated by the thermal decomposition of N2O. Three mixtures, each diluted in argon, were studied: 0.6 mol % of C3F6 With 1.5 mol % N2O; 6.2 mol % of C3F6 With 0.6 mol % of N2O; and 6.3 mol % of N2O and 0.7 mol % of C3F6 The temperatures were in the range 1300-1600 K, the residence times behind the reflected shock were in the range 550-850 Cls, and the pressures were between 16 and 20 atm. Fluorinated products have been quantified with gas chromatography, oxidized products with Fourier transform infrared spectroscopy; identification of unknown fluorocarbons has been performed with gas chromatography-mass spectrometry. The most significant products detected were C2F6, C2F4, CF2O, CO, CO2, and CF4. A detailed kinetic scheme is presented to model the experimental reactant and product yields as a function of temperature. Modeling showed that O-addition to either carbon of the double bond of C3F6 occurs. The rate constant for O-addition to the terminal carbon of the double bond, C3F6 + O((3)p),--> (CF3CF)-C-3 + CF2O,was deduced to be k(71) = 10(12.7)T(0.05), exp(-0.4 kJ mol(-1)/RT) cm(3) mol(-1) s(-1), and for addition to the central carbon, C3F6 + O(P-3) -C CF3 + CF2CF=O, k(72) = 10(12.5) cm3 mol(-1) s(-1). Under oxidizer-rich conditions, ignition of the C3F6 occurred. Rate of production analyses showed that ignition was propagated by an F atom chain involving the CF2 + O and unimolecular CFO decomposition reactions. Under C3F6-rich conditions, single-and double-bond pyrolysis were the important destruction routes.