Overview: Effective Separation of Oxygen-, Nitrogen-, and Sulfur-Containing Aromatics in High-Temperature Coal Tar by Ionic Liquids and Deep Eutectic Solvents: Experimental and Computational

Heteroatom-containing aromatics (HACAs), such as oxygen-containing aromatics (OCAs), nitrogen-containing aromatics (NCAs), and sulfur-containing aromatics (SCAs), in high-temperature coal tar (HTCT) can be regarded as valuable chemicals. Ionic liquids (ILs)/deep eutectic solvents (DESs) play a crucial role for selectively extracting and purifying HACAs from HTCT, which can be attributed to the complex interactions, especially hydrogen bonds, between the ILs/DESs and HACAs. This paper mainly summarizes the separation of HACAs from a model oil and raw oil with ILs/DESs, the structural effect of ILs/DESs on HACA separation, as well as the interactions between ILs/DESs and different solutes by experimental and computational chemistry. Subsequently, HACA separation with ILs/DESs from HTCT was summarized. This review was expected to screen and develop suitable ILs/DESs with high selectivities to OCAs, NCAs, SCAs, and their homologues.