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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