Asphaltenes, resins and maltenes physical isolation procedures involving different alkane precipitants and solvent/sample ratios were applied in this work to Athabasca bitumen vacuum residue. Samples were characterized by Solubility Profiling, Size Exclusion Chromatography, Fluorescence Spectroscopy, X-ray Photoelectron Spectroscopy and density-viscosity analyses. Isolated fractions were found to display systematic property changes. Thus, it was found that denser, more polar, higher molecular weight (MW), more viscous, red shifted fluorescence materials were sequentially ranked as follows: Solvent extracted asphaltenes -C7 (unwashed) asphaltenes -C5 (unwashed) asphaltenes -resins -maltenes. Intermolecular aggregation for these fractions was determined to follow the same order. Decreasing contents of resins in the same order were found to increase aggregation phenomena.This work further reported on aspects of possible practical interest, i.e., the liquid nature of asphaltenes at 300°C and, possible existence of oxidative reactions affecting fractions isolation that follow standard methods which do not contemplate inert atmospheres. Preliminary assessment of chemical functionalities within isolated fractions highlighted on the possible enrichment of pyrrolic compounds within resins and oxygen functionalities in asphaltenes.

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C7 asphaltenes from Athabasca crude oil were hydrotreated using a commercial NiW/Al2O3 catalyst and analyzed using X-ray photoelectron spectroscopy. Results showed that the catalyst performed better in the removal of sulfur rather than nitrogen and that sulfur concentration is higher at the surface in comparison to the bulk structure. Moreover, the sample after reaction had a higher oxygen content in comparison to the untreated asphaltene, indicating poor hydrodeoxygenation performance of the catalyst in addition to a higher reactivity toward atmospheric oxygen at the surface of the asphaltene. The latter is proposed to arise once the layer of resin covering the asphaltene is partially converted during the hydrotreating process.

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