Oxidative desulfurization of model oil in an organic biphasic system catalysed by Fe₃O₄@SiO₂–ionic liquid

Abstract

Lewis or Brønsted acidic methylimidazolium ionic liquid-functionalized Fe 3 O 4 @SiO 2 nanoparticles were fabricated and applied as an efficient magnetic heterogeneous catalyst for dibenzothiophene (DBT) oxidation in a biphasic system using H 2 O 2 as the oxidant. The structures of catalysts were characterized by SEM, TEM, XRD, TGA, FT-IR, VSM and EDX techniques. The magnetic catalysts showed high catalytic performance in the oxidation of DBT in an n-hexane/acetonitrile biphasic system using H 2 O 2 , and high conversions were obtained. The effects of contact time, temperature, amount of H 2 O 2 and amount of catalyst on the DBT oxidative removal efficiency were investigated. The contact time of 60 min, 0.1 g catalyst, and 4 mL H 2 O 2 at 313 K were found as optimal experimental conditions for an improved DBT oxidative removal process. The sulfur level could be lowered from 100 ppm to less than 7, 5, and 2 ppm under optimal conditions for Fe 3 O 4 @SiO 2 -Mim-BF 4 , Fe 3 O 4 @SiO 2 -Mim-HSO 4 , and Fe 3 O 4 @SiO 2 -Mim-FeCl 4 , respectively. These nanomagnetic heterogeneous catalysts could be easily separated from the reaction mixture by applying an external magnetic field and recycled several times.Scheme 1 Preparation of Fe 3 O 4 @SiO 2 -methylimidazolium chloride. This journal isScheme 2 Schematic illustration of Fe 3 O 4 @SiO 2 -methylimidazolium chloride nanoparticles anion exchange. 34976 | RSC Adv., 2017, 7, 34972-34983 This journal isFig. 6 Energy dispersive X-ray spectroscopy of (a) Fe 3 O 4 @SiO 2 -Mim-BF 4 (b) Fe 3 O 4 @SiO 2 -Mim-HSO 4 and (c) Fe 3 O 4 @SiO 2 -Mim-FeCl 4 . This journal is Scheme 4 The suggested mechanism of DBT oxidation by Fe 3 O 4 @SiO 2 -Mim-BF 4 . This journal is Scheme 5 The suggested mechanism of DBT oxidation by Fe 3 O 4 @SiO 2 -Mim-HSO 4 . 34980 | RSC Adv., 2017, 7, 34972-34983 This journal is

Molybdenum Dioxide in Carbon Nanoreactors as a Catalytic Nanosponge for the Efficient Desulfurization of Liquid Fuels

“…[37,38] DBT was selected as it is commonly found in oil, thus presenting a real and important environmental issue in its own right, and has distinctive absorption features in the UV-vis spectrum, ensuring facile measurement of its concentration in model fuels ( Figure S2 constituent of fuel and represents a valuable model fuel simulant used in previous research. [37,38] DBT was selected as it is commonly found in oil, thus presenting a real and important environmental issue in its own right, and has distinctive absorption features in the UV-vis spectrum, ensuring facile measurement of its concentration in model fuels ( Figure S2 constituent of fuel and represents a valuable model fuel simulant used in previous research.…”

“…[39] In a typical ODS procedure, an organic peroxide-employed to avoid potential phase transfer limitations-in a ratio of 1:20 (S:O) was added to the model fuel and catalyst and stirred at 60 °C for 120 min. [21,38] Acetonitrile was selected as the solvent due to its known effectiveness toward the extraction of the DBT oxidation products and its reduced toxicity relative to other commonly utilized extraction solvents, such as dimethylformamide. [21,38] Acetonitrile was selected as the solvent due to its known effectiveness toward the extraction of the DBT oxidation products and its reduced toxicity relative to other commonly utilized extraction solvents, such as dimethylformamide.…”

“…To appraise the hybrid material for its ability to desulfurize fuel, a model system comprising 500 ppm dibenzothiophene (DBT) in n-hexane was identified. [37,38] DBT was selected as it is commonly found in oil, thus presenting a real and important environmental issue in its own right, and has distinctive absorption features in the UV-vis spectrum, ensuring facile measurement of its concentration in model fuels ( Figure S2 constituent of fuel and represents a valuable model fuel simulant used in previous research. [39] In a typical ODS procedure, an organic peroxide-employed to avoid potential phase transfer limitations-in a ratio of 1:20 (S:O) was added to the model fuel and catalyst and stirred at 60 °C for 120 min.…”

“…[6,21,37,39] Consistent with previous studies, we subsequently employed an extraction procedure in which the model fuel was vigorously stirred with acetonitrile (in a 1 to 5 ratio of extractant to fuel) for 30 min. [21,38] Acetonitrile was selected as the solvent due to its known effectiveness toward the extraction of the DBT oxidation products and its reduced toxicity relative to other commonly utilized extraction solvents, such as dimethylformamide. [40] Interestingly, it was noted that 27-30% of DBT can be removed from the fuel simply through extraction alone, reflecting the moderate solubility of DBT in n-hexane.…”

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

“…Although magnetic graphene oxide (mGO), a type of functionalized graphene‐based material, has been used in heavy metal removal processes, methanol oxidation, and proteome digestion, and in other fields of application, there have been no reports of its application in ODS until now. To facilitate the recycling process of catalysts, various magnetic materials, including HKUST‐1/Fe 3 O 4 , H 3+ n PMo 12− n V n O 40 /silica‐encapsulated γ‐Fe 2 O 3 , magnetic silica nanospheres, and Fe 3 O 4 @SiO 2 ‐ionic liquid, have been used as magnetically recoverable catalysts for ODS, thus making the recycling operation much easier and decreasing the catalyst loss in the conventional recycling process. Inspired by the studies discussed above, we expect that mGO will have promising applications for ODS.…”