Kinetic studies of coke formation in hydrocarbon fractions of heavy crudes

Abstract

Different types of bitumens [Athabasca and topped Athabasca bitumen, Cold Lake heavy oil, and light Arabian vacuum bottoms (pitch)] were separated into five fractions classified as follows: asphaltene, soft resin, hard resin, aromatics and saturates. The various fractions, and the bitumens themselves, were maintained at temperatures ranging from 395 °C to 510 °C under nitrogen and measurements made of the amounts of coke produced as a function of time. The results were analysed to give rate constants and activation energies for coke (toluene insoluble) formation. It was found that the rate of coke formation is greater the higher the degree of aromaticity of the feed stock. The results have led to a tentative mechanism for the formation of coke, which appears to be formed by a rapid reaction from large aromatics formed as intermediates. © 1986.