Kinetic mechanism for modeling the temperature effect on PAH formation in pyrolysis of acetylene

Abstract

The study proposes a refined kinetic mechanism to investigate the temperature effect on the formation of the 7 most abundant US-EPA (United States Environmental Protection Agency) PAHs in pyrolysis of acetylene. This work is motivated by the issue that the previously published kinetic mechanisms of C2H2-PAH exhibit very limited consistency and accuracy to predict C2H2 conversion rate and formation of two- to four-ring aromatics. Based on the previous investigations using a tubular flow reactor, we propose a reactor module consisting of three serially connected 1-D plug-flow reactors, where preheating, heat release and isothermal conditions are considered. The reactor configuration is capable of improving the prediction of C2H2 conversion and PAH formation during the pyrolysis of acetylene at 970–1360 K and 1 atm. In addition, the present mechanism made up of 290 species and 1175 reactions is the refined integration of previous kinetic databases, and its computed results are in satisfactory agreement with experimental values. Using the computed spatial distributions of mole fractions along the serially connected 1-D tubes, we interpret the temperature effect on the outlet mole fractions that were previously detected by gas chromatography–mass spectrometry. Finally, we analyze the temperature effect on reaction pathways leading to the formation of PAHs.