Deep Desulfurization of Fuel Oils Using Low-Viscosity 1-Ethyl-3-methylimidazolium Dicyanamide Ionic Liquid

Abstract

In this work, the extractive and oxidative deep desulfurizations of model fuel oils using a low-viscosity ionic liquid, i.e., 1-ethyl-3-methylimidazolium dicyanamide ([C2mim][N(CN)2]), are investigated. [C2mim][N(CN)2] is capable of effectively extracting thiophene (TS) and dibenzothiophene (DBT) from oils. The sulfur content in the raffinate phases is only ∼10 ppm after a few extraction steps. A short extraction equilibrium time of <5 min is observed. The extraction operation is insensitive to temperature, and it can be effectively performed at or around room temperature. Unexpectedly, the oxidative removal of DBT by such a dicyanamide-based ionic liquid is not effective and is not as good as the corresponding extraction operation. Such an undesirable oxidative desulfurization is understood at a molecular level from ab initio calculations, and it may be ascribed to the strong intermolecular interaction between CH3COOH or CH3COOOH and [C2mim][N(CN)2] phase. Therefore, such a dicyanamide-based ionic liquid is efficient for direct extractive desulfurization, while it is less efficient for oxidative desulfurization.

Imidazolium ionic liquid as energy efficient solvent for desulfurization of liquid fuel

“…The result indicated the reaction can fast to reach equilibrium. It is obviously seen that these imidazolium base IL are more capable of effectively extracting DBT than other S-containing compounds [40,41]. This observation was also reported in other ILs extraction process that imidazolium based ILs has been attributed to the higher polarisable electron p-electron density of DBT which tends to insert the molecular structure of ILs [16,42].…”

Extractive Desulfurization of Fuel Oils with Thiazolium-Based Ionic Liquids

“…It is clearly seen that these thiazolium-base ILs are more capable of effectively extracting DBT than TS. The authors previously observed that using the dicynamide-based ILs, DBT is more efficiently extracted than TS (33,34). This observation was also reported in other ILs extraction system such as pyridinium-and imidazolium-based ILs (2,7,8,9,16), and has been attributed to the higher polarizable p-electron density of DBT which tends to insert into the molecular structure of the ILs.…”

Recent Advances in the Science and Technology of Desulfurization of Diesel Fuel Using Ionic Liquids

“…The extractive and oxidative deep desulfurizations of model fuel oils using a low-viscosity ionic liquids, i.e.,1-ethyl-3-methylimidazolium dicyanamide ([C 2 mim][N(CN) 2 ]), are investigated by Yu and coworkers [70]. [C 2 mim][N(CN) 2 ] is capable of effectively extracting thiophene (TS) and dibenzothiophene (DBT) from oils.…”