Imidazole-ionic liquid-assisted solvent extraction mechanism-macro perspective and molecular aspect

In recent years, heavy oil-solid separation has attracted quantities of attention, and ionic liquids (ILs) enhanced solvent extraction has been widely studied. However, the detailed mechanism of ILs effect onto the heavy oil recovery was unclear, especially the interaction role between ILs and heavy oil SARA. In order to solve these problems, this paper used the experiment and molecular dynamics simulation methods to explore the four ILs ([Bmmim][PF₆], [C₁₂mim][Ac], [C₁₂mim][BF₄], and [Emim][Ac]) effect on enhancing the solvent extraction for oil sands. The experimental results showed that the ILs could enhance the solvent extraction process, improve heavy oil recovery, reduce bitumen viscosity, decrease oil-sand interaction force, alter the sand particles wettability. The extraction efficiency of [Bmmim][PF₆] + toluene reached 93.9 %. Additionally, molecular dynamics (MD) simulations were conducted to analyze the interaction mechanisms between heavy oil SARA (saturates, aromatics, resins, asphaltenes) and solvents and ILs. The simulations results indicated that the saturates, aromatics, resins and asphaltenes have different interaction role with the different ILs under varieties of solvents, and the interaction role strength was related to the functional groups and heteroatom. In the end, the detailed mechanism of ILs enhancing solvent extraction for oil sands was put forward.