Deep oxidative–extractive desulfurization of fuels using benzyl-based ionic liquid

Four benzyl-based ionic liquids (ILs) were synthetized and used for deep desulfurization of model oil and real diesel fuel. The removal efficiencies of benzothiophene (BT) and dibenzothiophene (DBT) with [Bzmim][NTf 2 ] and [Bzmim][SCN] as extractants are higher than that with [Bzmp][NTf 2 ] and [Bzmp][SCN] as extractants. The desulfurization capability follows the Nernst's Law. A reactive extraction mathematical model for desulfurization was established. An oxidative-extractive two-step deep desulfurization method was developed. DBT was first oxidized by H 2 O 2 with CH 3 COOH as catalyst and then the unoxidized DBT and uncrystallized dibenzothiophene sulfoxide (DBTO 2 ) in model oil were extracted by [Bzmim][NTf 2 ], and finally the removal efficiency was 98.4% after one-stage extraction. Besides, the removal efficiency of 4,6-DMDBT was 96.4% after oxidation and one-stage extraction processes. Moreover, the oxidative-extractive two-step deep desulfurization method was also effective for desulfurization of diesel fuel. The removal efficiency of sulfur reached up to 96% after oxidation and three-stage cross-current extraction processes. © 2016 American Institute of Chemical Engineers AIChE J , 62: 4023–4034, 2016