Review on Applications of Ionic Liquids (ILs) for Bitumen Recovery: Mechanisms, Challenges, and Perspectives

Water- and solvent-based ex situextraction processes have beenemployed to extract bitumen from mineable oil sands. On the otherhand, bitumen is recovered in situ from deeper deposits most efficientlyby injecting steam to reduce viscosity and increasing production flowto the surface. However, the water-based process with or without solvent(including steam injection) is not sustainable due to various challengesincluding water requirement and treatment, high energy consumption,and related environmental pollution problems emanating from high volatilityof solvents. Ionic liquids (ILs) have become desirable in severalindustrial applications due to many unique properties including lowvolatility compared with traditional organic solvents. The potentialfor application of ILs for bitumen extraction is reviewed in thiswork, with a focus on the mechanistic aspect. Depending on the propertiesand/or functionality, the ILs can be used in bitumen extraction (withor without organic solvents) with minimal clay fines contaminationand lower water and energy requirements. In the solvent-assisted ILrecovery system, the IL-clay interaction is responsible forreducing the adhesive force between bitumen and the sand, which subsequentlyfacilitates separation. Conversely, considering the types of ILs exploredin the absence of solvent, the IL-bitumen interaction playsan additional role. Hitherto, applications of ILs in bitumen recoveryare at a very preliminary stage. Apart from understanding the mechanisms,the major impediment lies in the high cost and environmental impactdue to toxicity. Therefore, to make ILs more attractive for bitumenrecovery, concerted efforts should be intensified to reduce the costof producing ILs, ameliorate environmental impacts, and facilitatefield scale applications through technoeconomic analysis of the process.

Automated summary

This study reviews the potential application and mechanism of ionic liquids (ILs) in bitumen extraction from oil sands. ILs have the ability to reduce clay impurities and decrease water and energy requirements in solvent-assisted systems, which improves bitumen recovery efficiency.