Deep Oxidative Desulfurization of Fuel Oils Catalyzed by Decatungstates in the Ionic Liquid of [Bmim]PF₆

Abstract

Three decatungstates with short carbon chains as the cations, such as tetrabutylammonium decatungstate ([(C4H9)4N]4W10O32), tetramethylammonium decatungstate ([(CH3)4N]4W10O32), and benzyltriethylammonium decatungstate ([(C2H5)3NC7H7]4W10O32), were synthesized and then used as a catalyst in the extractive catalytic oxidative desulfurization (ECODS) system in the ionic liquid (IL) of [Bmim]PF6, and hydrogen dioxide (H2O2) was used as an oxidant. During the optimized process, the sulfur level in the model oil (1000 ppm S) can be reduced to 8 ppm, which is consistent with the standards of deep desulfurization. The temperature, the reaction time, and the amount of H2O2 and catalyst, as well as the type of the cations of decatungstates, all played vital roles in desulfurization efficiency, which were studied in detail to optimize the reaction conditions. The system could be recycled five times before the sulfur removal decreased sharply.

Oxidative processes of desulfurization of liquid fuels

“…Consequently, efforts have been devoted to the development of processes using highly robust and recyclable catalysts which provide higher atom utilization and minimize pollution levels using greener ingredients. [120][121][122] can remove the majority of sulfur with a low hydrogen peroxide sulfur ratio. This finding provides evidence in favour of combining catalytic oxidation and extraction.…”

Oxidative Desulfurization of Gasoline by Ionic Liquids Coupled with Extraction by Organic Solvents

“…38 In a typical ODS, S-compounds in gasoline fuel are extracted into the IL phase first, then oxidized by some oxidant, and the oxidized product is more polar and easily removable. The oxidant is usually the cheap and environmentally benign hydrogen peroxide (H 2 O 2 ) solution, while the catalysts are usually acetic acid, 39 vanadium pentoxide, 40 decatungstates, 41 peroxotungsten, or peroxomolybdenum complexes. 42 Due to regeneration and contamination problems of acid catalyst, recently, some acidic ILs have been used in ODS, where those ILs act as both catalyst and solvent, and no other acid catalyst is added, as shown in Figure 2.…”

Ionic liquids on desulfurization of fuel oils

“…It was proved that desulfurization yield is increased by about one order of magnitude compared with merely extracting with ILs. Several authors had already tried this idea adding H 2 O 2 as oxidant with several catalysts as acetic acid [59], phosphotungstenic acid [60], decatungstates [61], V 2 O 5 [62], and several different ionic liquids (quaternary ammonium coordinated ionic liquids [63], n-methyl pyrrolidinium ionic liquids [64] or even task-specific ionic liquids Table 1 CAS-register number, water mass fraction (ωH 2 O ), density ( ) and refractive index (nD) of the pure components at 298.15 K and atmospheric pressure. [70] and CuCl 2 [46] or ZnCl 2 [71] are being studied.…”