Experimental and kinetic modeling study of butene isomer pyrolysis: Part I. 1- and 2-Butene

1- and 2-Butene pyrolysis experiments were performed using a tubular flow reactor at an absolute pressure of ∼0.82 atm over a temperature range of 535-810 °C with residence times ranging from ∼0.5-∼2.4 s. The initial concentration of the fuel ranged from 5 to 50 mol%. These data were compared to the predictions of a fundamentally based detailed kinetic model. For both sets of experiments, the model accurately predicts the observed fuel conversion, production of light products, and the formation of several important molecular weight growth species. The primary pathways that lead to the fuel decay and major product formation are discussed. One of the important kinetic features of 1- and 2-butene pyrolysis is that significant amounts of 1,3-butadiene are produced. The addition reactions of vinyl, allyl, and methyl allyl radicals to 1,3-butadiene are all energetically favorable, leading to substantial production of higher molecular weight species. The model was also applied to published pyrolysis and oxidation data for 1- and 2-butene that were collected under significantly different conditions. The comparison to the latter data sets illustrate that, even under oxidation conditions, it is important to properly account for the pyrolysis kinetics.