Kinetics of the consumption of CF3H, CF2 HCl and CF2O in H2/O2 flames

The structure of two premixed lean and stoichiometric H2/O2/Ar/CF3H flames and of a stoichiometric H2/O2/Ar/CF2HCl flame has been established using a mass spectrometer coupled with molecular beam sampling. The main goal of this work is to study the first step of the CF3H - and the CF2HCl - consumption by reaction with radicals in flames. The rate coefficients of reactions (1) CF3H + 3H → products and (2) CF3H + O → CF3 + OH have been determined: k1= 1.16 1014 exp(-8800/T) cm3 mole-1 s-1 in the temperature range 960 - 1300 K and k2= 1.10 l012 exp(-1600/T) cm3 mole-1 s-1 in the temperature range 920 - 1150 K. In the lean flame 5% of CF3H is consumed by H, 83% by O and 12% by OH, while in the stoichiometric flame 40% is consumed by H, 42% by O and 18% by OH. The determination of the rate coefficient of the reaction (4) CF2HCl + H → CF2H + HCl in the CF2HCl containing flame leads to the expression k4 = 4.65 1014 exp(-7730/T) cm3mole-1s-1 in the temperature range from 930 to 1155 K. The rate coefficient of the reaction (7) CF2O + H → CFO + HF determined in the burnt gases of the investigated flames is k7= 4.50 1013 exp(-11500/T) cm3mole-1s-1 between 1175 and 1490 K.