Coke production from an FCC-decant oil: characterization of the thermal process

Abstract Detailed characterization of the thermal transformation of a decant oil, obtained from a fluid catalytic cracking (FCC), in a closed system makes it possible to determine the mode and timing of coke production. A fast dismutation process into light and heavy liquid products is observed, followed by slow production of coke with an activation energy of only 150 kJ mol −1 . From elemental analysis, nuclear magnetic resonance (n.m.r.) and mass spectra, dehydrogenation and condensation reactions are detected. These results are well modelled by the pyrolysis of a set of 1-aryl, 2-phenylethylene compounds (aryl = two to four aromatic rings) under the same conditions. The phenanthrenic derivative presents a similar thermal profile towards coke production. The first steps are mainly dominated by non-radical processes such as electrocyclic reactions.