Detailed kinetic modeling of soot formation in hydrocarbon pyrolysis behind shock waves

A new detailed kinetic model of soot formation in hydrocarbon pyrolysis under conditions typical for shock tube experiments was developed. It combines the mechanism of formation of polyaromatic hydrocarbons, polyyne, and H-abstraction-C2H2-addition (HACA) pathways of soot formation and the mechanisms of acetylene pyrolysis and pure carbon cluster formation. The kinetic model was tested for various aliphatic and aromatic hydrocarbons and their mixtures, and it showed the role of the polyyne and HACA pathways in soot formation under various conditions for different hydrocarbons. All the numerical results presented were calculated while keeping the reaction mechanism and the entire set of the rate coefficients fixed. The comparison of the calculations with the experimental measurements clearly shows that the coincidence is quantitatively good for all the main parameters of soot formation. It is worth remarking that the calculations have been performed for hydrocarbons with different chemical structures, both aliphatic and aromatic, and also for a wide range of temperature and pressure. Therefore, the model can be expected to describe soot formation for other molecules, including larger ones with more complex chemical structures and even for hydrocarbon mixtures.