Acetylene oxidation: The reaction C 2H 2+O at high temperatures

Abstract

Shock heating, together with atomic and molecular resonance absorption spectrometry was used for simultaneous monitoring of H and O or CO in highly diluted acetylene-nitrous oxideargon mixtures. The investigations covered a temperature and pressure range of 1500 to 2500 K and 1.5 to 2.0 bar respectively. New measurements are presented for the primary step: C 2 H 2 + O = C H 2 + C O ( R 2 a ) H C C O + H ( R 2 b ) The channel ratio, k 2b /(k 2a +k 2b ) was found to be about 0.64 in the temperature range investigated. Best fits for the measured H and O profiles were achieved with k 2 a = 1.6 × 10 14 exp ⁡ ( − 4 , 975 / T ) k 2 b = 4 × 10 14 exp ⁡ ( − 5 , 365 / T ) (All rate coefficients in cm 3 mol −1 s −1 ). The fact that channel 2 b is faster than 2 a is in qualitative agreement with theoretical predictions. To reach the above conclusions, high temperatures ketyl and methylene oxidation kinetics were investigated. The following rate coefficients were determined for some significant reactions. C 3 H 2 + O ( P 3 ) = C O + 2 H ( R 9 a ) C O + H 2 ( R 9 b ) k = 8 ± 1 × 10 13 k = 4 ± 1 × 10 13 H C C O + O ( P 3 ) = 2 C O + H ( R 3 ) k = 1 × 10 14 H C C O + H = C 1 H 2 + C O ( R 4 ) k = 1.5 × 10 14 H C C O + A r = C H + C O + A r ( R 5 ) k = 6 × 10 15 exp ⁡ ( − 29600 / T ) C H + O = C O + H ( R 6 ) k = 1 − 1.5 × 10 14