Extractive desulfurization of diesel fuel by amide-based type IV deep eutectic solvents

As promising green alternative solvents for ionic liquids, deep eutectic solvents (DESs) have been widely used in separation, catalysis, synthesis, etc. Most of the researches have focused on the application of DESs formed by hydrogen bonding interaction. In this paper, amide-based type IV DESs were synthesized from metal chloride and amides with coordination interaction, and they were used for extractive desulfurization of fuels. The experimental results showed the DES ZnCl2/N-methylformanilide (ZnCl2/MFA) had the highest desulfurization efficiency with the Nernst partition coefficient (KN) as 2.41. The extraction mechanism was firstly explored by Fourier transform infrared spectrometer (FT-IR) and 1H nuclear magnetic resonance (1H NMR). Then density functional theory (DFT) study suggested that π-π interactions and CH···π interactions contribute mainly to effective removal of DBT from fuel oil by DESs.