Coking of Athabasca end cut : Residuum/asphaltene/coke/solids. Characterization in petroleum processing

Athabasca end cut is the residue fraction of supercritical fluid extraction (SCFE) with 524°C + Athabasca bitumen pitch. Most of sulfur, nitrogen, nickel and vanadium species in bitumen are concentrated in the end cut. In fact, this residue fraction, accounting for 18% of the bitumen, contains 30% of total sulfur in bitumen, 44% of total nitrogen, 62% of total microcarbon residue, and 80% of total nickel or vanadium. For SARA (saturate, aromatic, resin and asphaltene) analysis, end cut contains about 88% of asphaltene, 10% of resin, and 2% of aromatics. So end cut is a fraction comprised of very large and complex molecules. Through comparing the reactivity of sub-fractions of SCFE, it has been found that at different reaction conditions (coking, non-catalytic hydrocracking and catalytic hydrocracking), the heaviest fraction had the lowest cracking reactivity. It was also found that the quantity (18%) of the heaviest fraction recovered from bitumen is comparable to coke yield (about 20%) in coking process (1, 2).