Energy & Fuels, Vol.29, No.8, 4927-4935, 2015
Extraction of Bitumen from Oil Sands Using Deep Eutectic Ionic Liquid Analogues
It is demonstrated that bitumen can be separated from "water-wet" Alberta oil sands and "oil-wet" Utah oil sands using a so-called analogue ionic liquid (IL) based on deep eutectic mixtures of choline chloride and urea (ChCl/U) together with a diluent such as naphtha. Unlike conventional ILs, these eutectics are relatively cheap and environmentally friendly. The process is straightforward and involves simply mixing the components at ambient temperatures followed by standard solid/liquid and liquid/liquid separation steps. The ChCl/U mixture appears to reduce the adhesion of bitumen to sand, facilitating separation. It is also immiscible with hydrocarbons such as bitumen or oil. Coupled with a large density difference, this results in a sharp phase separation of hydrocarbons from the ChCl/U mixture. The ChCl/U deep eutectic essentially acts as a separating fluid, keeping the naphtha-diluted bitumen and extracted sand apart, facilitating subsequent separations and solvent recovery steps. However, ChCl/U mixtures are highly viscous at ambient temperatures, but high concentrations of this deep eutectic in water also work well. Initial scale-up work suggests that this approach may form the basis for a viable large-scale process.