Theoretical and kinetic modeling study of chloromethane (CH3Cl) pyrolysis and oxidation

This work presents a comprehensive kinetic modeling study of the pyrolysis and oxidation of chloromethane. Theoretical calculations were performed for the decomposition reaction CH3Cl + M = CH3 + Cl + M and for a set of relevant H-abstraction reactions (CH3Cl + R, R = Cl, Ḣ, ȮH, HȮ2, O2, Ö, ĊH3, Ċ2H3, Ċ2H5; CH4 + Cl, C2H6 + Cl, C2H4 + Cl, C2H2 + Cl). Comparison with previous experimental or theoretical determinations, when available, proved the appropriateness of the adopted protocols and the accuracy of the calculated rate constants. Previously developed subsets for CH3Cl and HCl/Cl2 were updated with the theoretical rate constants and combined with the CRECK C1–C3 mechanism, yielding a kinetic mechanism consisting of 143 species and 2347 reactions. The validation was performed through comparison with all the pyrolysis and oxidation measurements available for pure CH3Cl and its mixtures with CH4, H2, and CO/H2O. The kinetic discussion highlights the role of key reaction steps that have been theoretically investigated in this work and in previous efforts and sheds light on additional reaction pathways needing better assessments.