Kinetics and mechanism for oxidative desulfurization of fuels catalyzed by peroxo-molybdenum amino acid complexes in water-immiscible ionic liquids

A facile sol–gel method based on urea–SnCl2 deep eutectic solvents for the synthesis of SnO2/SiO2 with high oxidation desulfurization activity

The n%-SnO2/SiO2 (n = 2, 4, 6) supported catalyst was prepared by the sol–gel and calcination method. Compared with the traditional impregnation method, the catalyst prepared by sol–gel method has higher oxidative desulfurization activity.

Keggin polyoxometalates encapsulated in molybdenum-iron-type Keplerate nanoball as efficient and cost-effective catalysts in the oxidative desulfurization of sulfides

In this work, the catalytic activity of core-shell-type polyoxometalate (POM) composites, comprised from Keggin POMs encapsulated in Mo₇₂Fe₃₀ Keplerate, in the oxidation of various sulfides into corresponding sulfoxides or sulfones and oxidative desulfurization of dibenzothiophene with hydrogen peroxide are investigated. From the results, the catalytic activity of these Keggins encapsulated in Keplerate are better than parent ones and among them BW₁₂ ⊂ Mo₇₂Fe₃₀ showed the best results. The operationally simple oxidation reactions at room temperature, high to excellent yields and chemoselectivity, short reaction times, and the use of H₂O₂ as oxidant are some of the other advantages in this catalytic system. Also, the synergistic effect of Keggin POMs and Mo₇₂Fe₃₀ Keplarate has been confirmed.

Polyoxometalate as an effective catalyst for the oxidative desulfurization of liquid fuels: a critical review

In order to meet the stringent environmental and industrial legislation on fuel specifications, sulfur compounds have to be removed efficiently from fuels. The requirement to produce ultralow-sulfur fuels (S < 10 ppm) has stimulated many works in the area of conventional hydro-desulfurization (HDS) method. Oxidative desulfurization (ODS), as an alternative or complementary technology to HDS for deep desulfurization, is conducted with high selectivity and reactivity to sterically hindered S compounds under mild reaction conditions. In the ODS process, using an appropriate oxidant in the presence of a catalyst, organic sulfur compounds can be oxidized selectively to their corresponding sulfoxides and sulfones, which can be easily removed by different separation methods. Having great catalytic characteristics, polyoxometalate materials have been utilized as a vital class of catalysts for deep desulfurization of fuels. In the past few decades, ODS of fuels using polyoxometalate as catalyst has drawn much attention, and various studies have been carried out in this area. Here, we give a critical review for the removal of sulfur compounds from liquid fuels (mostly from diesel and model fuels) by ODS via homogeneous and heterogeneous polyoxometalate catalysts.

Propionic acid-based deep eutectic solvents: synthesis and ultra-deep oxidative desulfurization activity

Propionic acid-based deep eutectic solvents (C₃H₆O₂/X ZnCl₂, X from 0.1 to 0.6) were synthesized by stirring a mixture of propionic acid and zinc chloride at 100 °C.

Trifluoromethanesulfonic acid-based DESs as extractants and catalysts for removal of DBT from model oil

The ChCl·1.5CF₃O₃S DESs is synthesized by stirring at the room temperature. The high efficient desulfurizative system using ChCl·1.5CF₃O₃S DESs as extractant and catalyst, H₂O₂ as oxidant with small amount of H₂O₂ (an O/S molar ratio of 6) and the low temperature (40 °C).

Extractive and oxidative desulfurization of model oil in polyethylene glycol

One-pot extractive and oxidative desulfurization of model oil in polyethylene glycol.

A recyclable ionic liquid-oxomolybdenum(vi) catalytic system for the oxidative desulfurization of model and real diesel fuel

The extractive and catalytic oxidative desulfurization (ECODS) of model and real diesel has been studied using the complex [MoO₂Cl₂(di-tBu-bipy)](1) (di-tBu-bipy = 4,4′-di-tert-butyl-2,2′-bipyridine) as a (pre)catalyst, aq. H₂O₂ as an oxidant, and either acetonitrile or an ionic liquid (IL) as a solvent and extractant.

Oxidative Desulfurization of Fuels Using Ionic Liquids: A Review

Extractive oxidation, wherein aromatic sulfur compounds are extracted and subsequently oxidized to their corresponding sulfones, has proven to be one of the most effective desulfurization methods for producing ultra-low sulfur content fuels. As non-volatile and highly designable solvents, ionic liquids (ILs) have attracted considerable attention for the oxidative desulfurization of fuels. In this review, we systematically discuss the utility of ILs in catalytic extractive oxidation, including their roles as extractants, catalysts, or dual extracting/catalytic species for this application. We also discuss the challenges facing the use of ILs in this regard, including their relatively high costs and excessive viscosities, as well as the efficiencies and stabilities of catalysts presently being considered within them.

Hydrophobic mesoporous silica-supported heteropolyacid induced by ionic liquid as a high efficiency catalyst for the oxidative desulfurization of fuel

The hydrophobic HPMo-IL/SBA-15 material served not only as a high-efficiency catalyst but also as an adsorbent.

A green procedure for direct oxidation of organic halides to aldehydes and ketones catalyzed by a molybdate-based catalyst

The direct oxidation of various primary and secondary halides to the corresponding aldehydes and ketones using 30% H₂O₂ as a green oxidant has been investigated using a molybdate-based heterogeneous magnetic catalyst.

Structural characterization of α-amino acid complexes of molybdates: a spectroscopic and DFT study

A joint spectroscopic and computational study has allowed us to determine the dinuclear structural core of the products of the reactions between molybdates and α-amino acids in aqueous medium.

Ultra-deep desulfurization via reactive adsorption on peroxophosphomolybdate/agarose hybrids

A catalyst system composed of peroxophosphomolybdates as catalytic center and agarose as matrix material had been designed. The [C16H33N(CH3)3]3[PO4{MoO(O2)2}4]/agarose (C16PMo(O2)2/agarose) hybrid was found to be active for oxidation desulfurization (ODS) of dibenzothiophene (DBT) or real fuel into corresponding sulfone by H2O2 as an oxidant, while the sulfur content could be reduced to 5ppm. The higher activity comes from its components including [PO4{MoO(O2)2}4] catalytic sites, the hydrophobic quaternary ammonium cation affinity to low polarity substrates, and agarose matrix affinity to H2O2 and sulfone. During the oxidative reaction, the mass transfer resistance between H2O2 and organic sulfurs could be decreased and the reaction rate could increase by the assistance of agarose and hydrophobic tails of [C16H33N(CH3)3]3[PO4{MoO(O2)2}4]. Meanwhile, the oxidative products could be adsorbed by agarose matrix to give clean fuel avoiding the post-treatment. In addition, the hybrid was easily regenerated to be reused.

A review of extractive desulfurization of fuel oils using ionic liquids

Extractive desulfurization of fuel oils using ionic liquids as extractive reagents.

Deep extractive and oxidative desulfurization of dibenzothiophene with C5H9NO·SnCl2 coordinated ionic liquid

A new C5H9NO·SnCl2 coordinated ionic liquid (IL) was prepared by reacting N-methyl-pyrrolidone with anhydrous SnCl2. Desulfurization of dibenzothiophene (DBT) via extraction and oxidation with C5H9NO·SnCl2 IL as extractant, H2O2 and equal mol of CH3COOH as oxidants was investigated. The Nernst partition coefficients k(N) of C5H9NO·SnCl2 IL for the DBT in n-octane was above 5.0, showing its excellent extraction ability. During the oxidative desulfurization process, the optimal molar ratio of H2O2/DBT was six. Sulfur removal of DBT in n-octane was 94.8% in 30 min at 30 °C under the conditions of H2O2/DBT molar ratio of six and V (IL):V (oil)=1:3. Moreover, the sulfur removal increased with increasing temperature because of the high reaction rate constant, low viscosity, and high solubility of dibenzothiophene-sulfone in the IL. The kinetics of oxidative desulfurization of DBT was also investigated, and the apparent activation energy was found to be 32.5 kJ/mol. The IL could be recycled six times without a significant decrease in activity.