Hexacyanoferrate‐based ionic liquids as Fenton‐like catalysts for deep oxidative desulfurization of fuels

Abstract

Two hexacyanoferrate-based ionic liquids, [C 4 Py] 3 Fe(CN) 6 and [C 16 Py] 3 Fe(CN) 6 , were synthesized and characterized using Fourier transform infrared and mass spectroscopies and CHN analysis. They were employed as Fenton-like catalysts in extraction and catalytic oxidative desulfurization of model oil with dibenzothiophene (DBT), benzothiophene (BT), 4,6-dimethyldibenzothiophene (4,6-DMDBT), 4-methyldibenzothiophene (4-MDBT) and 3-methylbenzothiophene (3-MBT) as substrates. Various polar solvents, such as ionic liquids, water and organic solvents, were applied to choose a suitable extractant. The results showed the removal of DBT reached 97.1% with [C 4 Py] 3 Fe(CN) 6 as a catalyst and 1-n-octyl-3-methylimidazolium hexafluorophosphate ([C 8 mim]PF 6 ) as an extractant under optimal conditions. The activity of sulfur removal followed the order DBT > 3-MBT > BT > 4-MDBT >4,6-DMDBT. The effect of water content on sulfur removal was investigated by adding various concentrations of H 2 O 2 . It was found that excess water had a positive effect on sulfur removal but the catalysts were less sensitive than [FeCl 4 À ]-based catalysts to water. The mechanism was studied using electron spin-resonance spectroscopy and gas chromatography-mass spectrometry. O 2•À may be the active oxygen species in the catalytic oxidative desulfurization process and the oxidation products of various sulfur compounds were the corresponding sulfoxides and sulfones.

Metal-Based Ionic Liquids in Oxidative Desulfurization: A Critical Review

“…S6). 101 Results showed the positive effect of excess water on sulfur removal and the lower sensitivity of [C 4 Py] 3 Fe(CN) 6 to water than [FeCl 4 ] − , which led to a higher desulfurization efficiency with [C 4 Py] 3 Fe(CN) 6 than MILs containing [FeCl 4 ] − .…”

“…The Fenton-like system composed of [C 4 Py] 3 Fe­(CN) 6 , [Omim]­[PF 6 ], and H 2 O 2 has been constructed for the catalytic oxidative removal of DBT, BT, 3-methylbenzothiophene (3-MBT), 4-methyldibenzothiophene (4-MDBT), and 4,6-DMDBT (Table S6). Results showed the positive effect of excess water on sulfur removal and the lower sensitivity of [C 4 Py] 3 Fe­(CN) 6 to water than [FeCl 4 ] − , which led to a higher desulfurization efficiency with [C 4 Py] 3 Fe­(CN) 6 than MILs containing [FeCl 4 ] − .…”

Improving generation of H2O2 and ·OH at bismuth hexacyanoferrate/graphene/carbon fibers-based gas diffusion electrode for degradation of dye wastewaters in photo-electro-Fenton process

“…These could result in an additional sources of • OH. Some iron hexacyanoferrate (FeHCF) and its derivatives (CoHCF and BiFeO 3 ) belonged to metal organic frame materials with good electro-activity, which have been, respectively, used as only heterogeneous photo-Fenton catalysts or only electro-catalysts (Wang et al 2019;Liu et al 2020;Jiang et al 2016b;Jassal et al 2015;Salles et al 2007;An et al 2013). However, there have been no report to use them as heterogeneous photo-electro-Fenton catalyst up to now.…”

Ultradeep desulfurization of model oil through the oxidative adsorption process using Dawson‐type polyoxometalates and graphene oxide multifunctional composites

“…However, harsh reaction conditions including high temperature, high pressure, and large hydrogen consumption must be provided for hydrodesulfurization, and its removal efficiency for heteroaromatic sulfur compounds such as benzothiophene (BT), dibenzothiophene (DBT), and 4,6‐dimethyldibenzothiophene (4,6‐DMDBT) is not satisfactory due to the steric hindrance effect on the S atom. Therefore, it is imperative to explore new desulfurization methods as a complement or alternative for the conventional process, and recent studies on this topic have focused on extraction, adsorption, biodesulfurization, pervaporation, and oxidative desulfurization (ODS) . Among these methods, ODS has been critically acclaimed by various researchers, because of its mild reaction conditions and high efficiency for the removal of heteroaromatic sulfur compounds.…”