An experimental and kinetic modeling study of three butene isomers pyrolysis at low pressure

Pyrolysis of three butene isomers (C4H8) including 1-butene (1-C4H8), 2-butene (2-C4H8) and i-butene (iC4H8) were studied from 900 to 1900 K at low pressure. Synchrotron vacuum ultraviolet (VUV) photoionization mass spectrometry with molecular-beam sampling technique was used for isomeric identification of products and intermediates and also for concentration measurement. Based on the experimental results, a kinetic model consisting of 76 species and 232 reactions was developed to simulate mole fractions of species. The mole fraction profiles of pyrolysis species predicted by the model are in good agreement with the experimental measurements. The decomposition pathways of C4H8 are illustrated according to the reaction flux analysis. Our analysis demonstrates that reaction sequences 1-C4H8 → aC3H5 → aC3H4 → pC3H4 → C2H2, 2-C4H8 → saxC4H7 → 1,3-C4H6 → C2H3 → C2H2 and iC4H8 → iC4H7 → aC3H4 → pC3H4 → C2H2 are the major decomposition pathways of 1-butene, 2-butene and i-butene, respectively.