Investigations on Pyrolysis of Isooctane at Low and Atmospheric Pressures

The pyrolysis experiments
of isooctane were conducted in a flow
tube at the temperature from 848 to 1123 K at 30 Torr and from 723
to 998 K at 760 Torr. The pyrolysis intermediates and products were
photoionized by synchrotron vacuum ultraviolet and detected by a reflectron
time-of-flight mass spectrometer. A pyrolysis model was developed
to compare the results with the experimental data to improve the combustion
mechanism and to clarify the important pyrolysis pathways of isooctane.
The model includes 321 species and 1569 reactions. It can be revealed
from the rate of production and sensitivity analyses that in the initial
decomposition of isooctane, unimolecular dissociation reactions are
more important than H-abstraction reactions. The reaction pathways
and branching ratios are affected by the change of pressures. The
reaction networks of C5–C2 unsaturated
hydrocarbons are dominated by the production of isobutene and propene
via various reaction channels. Small amounts of benzene and fulvene
are formed from the reactions of smaller radicals and molecules.