Extraction of hydrocarbons from Athabasca oil sand slurry using supercritical carbon dioxide

•Supercritical carbon dioxide was used to extract hydrocarbons from an Athabasca oil sand slurry.•A higher mixing rate and longer soak time increased extraction yields.•Higher pressure (24.1 MPa) and lower temperature (31 °C) increased hydrocarbon yields when a toluene cosolvent was added—indicating yields are directly influenced by SC-CO2 density.•Higher temperatures (60 °C) increased hydrocarbon yields in the absence of toluene—suggesting desorption resistant hydrocarbon components are released from the oil sand matrix slurry due to increasing temperature.•The best treatment condition (24.1 MPa, 31 °C, and toluene addition) produced an extract centering on C25.

The oil sands industry is seeking innovative technologies to address the water intensity and the high-energy consumption associated with current oil sands processing technologies. This research therefore investigates the use of supercritical fluid extraction (SFE) as an alternative to the current water-based extraction technology. Bitumen, a complex mixture of hydrocarbons, was extracted from an Athabasca oil sand slurry using supercritical carbon dioxide (SC-CO2). Preliminary experiments revealed the importance of a higher mixing speed and a longer static time on hydrocarbon yields. In a second set of experiments, when toluene was introduced as a modifier, a higher SC-CO2 density (i.e. high pressure, low temperature) led to higher extraction yields. In the absence of toluene, higher temperature conditions (i.e. lower SC-CO2 density) provided higher extraction yields—suggesting desorption resistant hydrocarbon components in the oil sand matrix slurry are released as a result of increasing temperature. Using gas chromatography-flame ionization detector (GC–FID), the experiment that produced the highest cumulative hydrocarbon extraction yield was analyzed for product quality and the extracted hydrocarbons were observed to center on C25.

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