ABSTRACT
Athabasca oil-sand bitumen was separated into maltenes and asphaltenes by n-pentane precipitation. Greater than 70% of the V and Ni present in the bitumen is found in the asphaltenes as nominally non-porphyrin species. Sequential methanol-acetone extractions of the asphaltenes resulted in reducing the V and Ni associated with the residual solid to 52.8% and 77.8%, respectively. UV-visible absorption spectroscopy and INAA showed that the extracted V was present as vanadyl porphyrins but that non-porphyrin Ni complexes made up most of the extracted Ni component. The data indicate that at least 47% of the V in the Athabasca bitumen is present as vanadyl porphyrin. The association of vanadyl porphyrins with asphaltenes may be an adsorption process, and the solvent extractability of the porphyrins appears to be controlled by the solubility of the asphaltenes in the methanol-acetone solvent.
