On the reaction of CH with CO studied in high temperature CH4/Ar + CO mixtures

Abstract

AbstractIn this study a ring dye laser spectrometer was employed for in‐situ measurements of CH concentrations in the reaction zone behind shock waves. The time dependent absorption in the Q‐branch of the A2Δ — X2Π band of CH at 431.1311 nm caused by the formation and consumption of CH radicals during the shock induced pyrolysis of a few ppm methane in argon was recorded. The CH concentration could directly be calculated from the measured absorption by applying the Lambert‐Beer law. By adding a few percent CO to the initial mixtures, the CH concentration profiles were significantly perturbed. Both the perturbed and unperturbed CH concentration profiles have been compared with those calculated from reaction kinetic simulations. A reaction mechanism describing the CH concentration history in the CH4/Ar and CH4/CO/Ar systems between 2900 K and 3500 K was developed. By a fitting procedure, a value of k1 = 1.85 × 1011 cm3 mol−1 s−1 was obtained for the most important perturbation reaction CH + CO → C2O + H.