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Title: Shock tube study of the oxidation of C{sub 3}F{sub 6} by N{sub 2}O

Abstract

The kinetics of the high-temperature oxidation of C{sub 3}F{sub 6} by O({sup 3}P) 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 N{sub 2}O. Three mixtures, each diluted in argon, were studied: 0.6 mol % of C{sub 3}F{sub 6} with 1.5 mol % N{sub 2}O; 6.2 mol % of C{sub 3}F{sub 6} with 0.6 mol % of N{sub 2}O; and 6.3 mol % of N{sub 2}O and 0.7 mol % of C{sub 3}F{sub 6}. The temperatures were in the range 1300--1600 K, the residence times behind the reflected shock were in the range 550--850 {micro}s, 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 C{sub 2}F{sub 6}, C{sub 2}F{sub 4}, CF{sub 2}O, CO, CO{sub 2}, and CF{sub 4}. 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 C{sub 3}F{sub 6} occurs.more » The rate constant for O-addition to the terminal carbon of the double bond, C{sub 3}F{sub 6} + O({sup 3}P) {yields} {sup 3}CF{sub 3}CF + CF{sub 2}O, was deduced to be {kappa}{sub 71} = 10{sup 12.7}T{sup 0.05} exp({minus}0.4 kJ mol{sup {minus}1}/RT) cm{sup 3} mol{sup {minus}1} s{sup {minus}1}, and for addition to the central carbon, C{sub 3}F{sub 6} + O({sup 3}P) {yields} CF{sub 3} + CF{sub 2}CF{double_bond}O, {kappa}{sub 72} = 10{sup 12.5} cm{sup 3} mol{sup {minus}1} s{sup {minus}1}. Under oxidizer-rich conditions, ignition of the C{sub 3}F{sub 6} occurred. Rate of production analyses showed that ignition was propagated by an F atom chain involving the CF{sub 2} + O and unimolecular CFO decomposition reactions. Under C{sub 3}F{sub 6}-rich conditions, single- and double-bond pyrolysis were the important destruction routes.« less

Authors:
; ;  [1]
  1. Univ. of Sydney, New South Wales (Australia)
Publication Date:
OSTI Identifier:
677960
Resource Type:
Journal Article
Journal Name:
Journal of Physical Chemistry A: Molecules, Spectroscopy, Kinetics, Environment, amp General Theory
Additional Journal Information:
Journal Volume: 103; Journal Issue: 30; Other Information: PBD: 29 Jul 1999
Country of Publication:
United States
Language:
English
Subject:
54 ENVIRONMENTAL SCIENCES; ATMOSPHERIC CHEMISTRY; OXIDATION; CARBON FLUORIDES; NITROUS OXIDE; CHEMICAL REACTION KINETICS; SHOCK TUBES; TEMPERATURE RANGE 1000-4000 K; MEDIUM PRESSURE; MATHEMATICAL MODELS

Citation Formats

Hynes, R G, Mackie, J C, and Masri, A R. Shock tube study of the oxidation of C{sub 3}F{sub 6} by N{sub 2}O. United States: N. p., 1999. Web. doi:10.1021/jp991065v.
Hynes, R G, Mackie, J C, & Masri, A R. Shock tube study of the oxidation of C{sub 3}F{sub 6} by N{sub 2}O. United States. https://doi.org/10.1021/jp991065v
Hynes, R G, Mackie, J C, and Masri, A R. 1999. "Shock tube study of the oxidation of C{sub 3}F{sub 6} by N{sub 2}O". United States. https://doi.org/10.1021/jp991065v.
@article{osti_677960,
title = {Shock tube study of the oxidation of C{sub 3}F{sub 6} by N{sub 2}O},
author = {Hynes, R G and Mackie, J C and Masri, A R},
abstractNote = {The kinetics of the high-temperature oxidation of C{sub 3}F{sub 6} by O({sup 3}P) 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 N{sub 2}O. Three mixtures, each diluted in argon, were studied: 0.6 mol % of C{sub 3}F{sub 6} with 1.5 mol % N{sub 2}O; 6.2 mol % of C{sub 3}F{sub 6} with 0.6 mol % of N{sub 2}O; and 6.3 mol % of N{sub 2}O and 0.7 mol % of C{sub 3}F{sub 6}. The temperatures were in the range 1300--1600 K, the residence times behind the reflected shock were in the range 550--850 {micro}s, 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 C{sub 2}F{sub 6}, C{sub 2}F{sub 4}, CF{sub 2}O, CO, CO{sub 2}, and CF{sub 4}. 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 C{sub 3}F{sub 6} occurs. The rate constant for O-addition to the terminal carbon of the double bond, C{sub 3}F{sub 6} + O({sup 3}P) {yields} {sup 3}CF{sub 3}CF + CF{sub 2}O, was deduced to be {kappa}{sub 71} = 10{sup 12.7}T{sup 0.05} exp({minus}0.4 kJ mol{sup {minus}1}/RT) cm{sup 3} mol{sup {minus}1} s{sup {minus}1}, and for addition to the central carbon, C{sub 3}F{sub 6} + O({sup 3}P) {yields} CF{sub 3} + CF{sub 2}CF{double_bond}O, {kappa}{sub 72} = 10{sup 12.5} cm{sup 3} mol{sup {minus}1} s{sup {minus}1}. Under oxidizer-rich conditions, ignition of the C{sub 3}F{sub 6} occurred. Rate of production analyses showed that ignition was propagated by an F atom chain involving the CF{sub 2} + O and unimolecular CFO decomposition reactions. Under C{sub 3}F{sub 6}-rich conditions, single- and double-bond pyrolysis were the important destruction routes.},
doi = {10.1021/jp991065v},
url = {https://www.osti.gov/biblio/677960}, journal = {Journal of Physical Chemistry A: Molecules, Spectroscopy, Kinetics, Environment, amp General Theory},
number = 30,
volume = 103,
place = {United States},
year = {1999},
month = {7}
}