Pyrolysis of propane for CVI of pyrocarbon: Part II. Experimental and modeling study of polyaromatic species

Abstract

In this work, we have studied the pyrolysis of propane at high temperature and low pressure. The pyrolysis produces various hydrocarbons from light species, such as methane or hydrogen, to polyaromatic hydrocarbons species (PAH), such as benzofluoranthene (C 20H 12). Experimental data have been obtained in a perfectly stirred reactor and in a wide range of temperature (1173–1298 K) and residence time (0.5–4 s). During the pyrolysis, 29 species were first identified by gas chromatograph–mass spectroscopy and quantified by gas chromatography (GC). In part I [I. Ziegler, R. Fournet, P.M. Marquaire, J. Anal. Appl. Pyrolysis, in press] of this work, a detailed kinetic mechanism (87 species involved in 386 reversible reactions) for the pyrolysis of propane was proposed, in order to reproduce the experimental gas phase species up to toluene. The validation of the mechanism was performed by simulations and comparisons with experimental data. The present work proposes an extended kinetic mechanism for the propane pyrolysis, in order to reproduce heavier species than toluene (608 reactions involving 172 species). This new mechanism allows to reproduce the formation of all the major products, identified experimentally, up to pyrene (C 16H 10). Based on the simulations performed, a flow rate analysis allows us to build the major route of the formation of PAH during the propane pyrolysis. The significant roles of radicals as propargyl (C 3H 3), cyclopentadienyl (C 5H 5) and indenyl (C 9H 7) in the formation of PAH will be discussed.