Oxidation of Reduced Sulfur Species: Carbon Disulfide

A detailed chemical kinetic model for oxidation of CS2 has been developed, on the basis of ab initio calculations for key reactions, including CS2 + O2 and CS + O2, and data from literature. The mechanism has been evaluated against experimental results from static reactors, flow reactors, and shock tubes. The CS2 + O2 reaction forms OCS + SO, with the lowest energy path involving crossing from the triplet to the singlet surface. For CS + O2, which yields OCS + O, we found a high barrier to reaction, causing this step to be important only at elevated temperatures. The model predicts low temperature ignition delays and explosion limits accurately, whereas at higher temperatures it appears to overpredict both the induction time for CS2 oxidation and the formation rate of [O] upon ignition. The predictive capability of the model depends on the accuracy of the rate constant for the initiation step CS2 + O2, which is difficult to calculate due to the intersystem crossing, and the branching fraction for CS2 + O, which is measured only at low temperatures. The governing reaction mechanisms are outlined on the basis of calculations with the kinetic model.