Incipient coke formation during heating of heavy hydrocarbons

Incipient coke formation was studied during heating of Athabasca pitch (+524 °C), heavy gas oils, their mixtures, and both distillation and solvent fractions in isothermal batch reactors at atmospheric pressure. Samples of about 1.5 g were reacted in open glass lined reactor tubes at temperatures from 360 to 420 °C over times from 0.3 to 7 h. Toluene insolubles and volatiles were measured in all experiments, with asphaltenes and heptane solubles in selected cases. Kinetic data are presented for toluene insoluble formation; results for pitch appear to follow the Wiehe series model for coke formation. The composition of the toluene insolubles formed is shown to depend on reaction severity.