New insights in the low-temperature oxidation of acetylene

This work presents new experimental data of C2H2 low-temperature oxidation for equivalence ratios Φ =  0.5-3.0 in a newly designed jet-stirred reactor over a temperature range of 600-1100 K at atmospheric pressure with residence time corresponding from 1.94 to 1.06 s. Mole fraction profiles of 17 intermediates including aromatic compounds such as toluene, styrene and ethylbenzene were quantified. A detailed kinetic mechanism involving 295 species and 1830 reactions was established to predict the oxidation of C2H2 and formation of PAH. In developing the mechanism, particular attention was paid to reactions of the vinyl radical and to steps involved in the sequence C2H2→iC4H5→fulvene→C5H5CH2→C6H6. In general, the peak concentrations of intermediates gradually increase and peak locations tend to shift toward high temperatures with Φ increasing. Flux analysis indicates that the addition of H and the reaction with O are the two major channels governing C2H2 consumption. At temperatures below 1000 K, benzene is mainly formed through the C2+C4 channels:C2H2+iC4H5→fulvene→C5H5CH2 isomers→C6H6.The C1+C5 pathway: CH3+C5H5→C5H5CH3→(fulvene and C5H5CH2 radicals)→C6H6 tends to be the dominant route for benzene formation at temperatures above 1000 K. In addition to the present data, the model predicts well ignition delay times reported in literature.