Shock initiated ignition in COS-O2-Ar mixtures

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Abstract
The ignition of COS + O2 mixtures diluted in argon was studied behind reflected shocks in a single‐pulse shock tube over the temperature range of 1100–1700°K. Ignition delay times and the distribution of reaction products before and after ignition were determined experimentally. From a total of 63 tests run at varying initial conditions, the following correlation for the induction times was derived: where β1 = +0.30, β2 = 1.12, and E = 16.9 kcal/mole. Using a reaction scheme of 14 steps, the following values were obtained by a computer modeling of the induction times: β1 = +0.22, β2 = 1.55, and E = 17.3 kcal/mole. The calculations showed that the reaction COS + S → CO + S2 caused the inhibiting effect of the COS. The reaction COS → O ± CO2 + S has a very strong accelerating effect, whereas the parallel channel COS + O → CO + SO shows the opposite effect. It was also shown that the reaction O + S2 → SO + O is very slow and does not contribute to the overall oxidation reaction. It is suggested that the rate constant given to the four‐center reaction COS + SO → CO2 + S2, that is, 1011 cm3/mole · sec at 300°K is incorrect. This constant is not much higher than 108 cm3/mole · sec at 1300°K.

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