Oxidative Desulfurization System Research Articles

Optimization of Desulfurization Process via Choline Phosphotungstate Coupled with Persulfate Using Response Surface Methodology

Using a simple acid-base neutralization method, a Ch-PW solid catalyst was synthesized by mixing choline hydroxide (ChOH) and phosphotungstic acid (HPW) at a 2:1 molar ratio in an aqueous solution. This catalyst was combined with a 20 wt.% potassium peroxymonosulfate (PMS) solution, using acetonitrile (ACN) as the extraction solvent to create an extraction catalytic oxidative desulfurization system. The optimal desulfurization conditions were determined through response surface methodology, targeting the highest desulfurization rate: 0.99 g of Ch-PW, 1.07 g of PMS, 2.5 g of extraction solvent, at a temperature of 50.48 °C. The predicted desulfurization rate was 90.79%, compared to an experimental rate of 93.64%, with a deviation of 3.04%. A quadratic model correlating the desulfurization rate with the four conditions was developed and validated using ANOVA, which also quantified the impact of each factor on the desulfurization rate: PMS > ACN > Ch-PW > temperature. GC-MS analysis identified the main oxidation product as DBTO2, and the mechanism of desulfurization in this system was further explored.

Boosting oxidative desulfurization from liquid fuels with CuO-MgO assisted by MgMoO4 co-catalyst

Developing a highly efficient catalyst is one of the important topics in the field of oxidative desulfurization from liquid fuels. In this study, the composite metal oxide catalysts (CuO-MgO) with co-catalyst MgMoO4 were prepared by co-precipitation method with simple process, high efficiency and good performance and their structures characterized. An efficient extractive catalytic oxidative desulfurization (ECODS) system for liquid fuel was successfully developed on the basis of as-prepared CuO-MgO-MgMoO4 (CuMgMo) as the catalyst, sodium hypochlorite (NaClO) as the oxidant, and acetonitrile as the extractant. Taking the n-decane and n-tetradecane containing dibenzothiophene (DBT) as the test model oil sample, the main parameters influencing desulfurization performance were examined in detail, such as the molybdenum content, the dosage of CuMgMo, the reaction temperature, the initial S-concentration, the different extractants, the volume ratio of extractant to oil, the different oxidants, and the molar ratio of NaClO to DBT. Based on optimized desulfurization reaction conditions, the model oil containing different sulfur compounds (benzothiophene, 4-methyldibenzothiophene, and 4,6-dimethyldibenzothiophene) and the real oil (straight-run gasoline, straight-run kerosene, and straight-run diesel) were further tested. Based on the free radical trapping experiments and the calculation of density functional theory, the reaction mechanism was deeply explored. The results showed that the de-electron reaction of DBT was mainly catalyzed by MgMoO4 and the reaction of HClO obtaining electron was mainly catalyzed by CuO. MgMoO4 plays an assisting role in improving the catalytic reaction rate. This work will provide a useful reference for the construction of efficient ECODS system using composite metal oxides.

Construction of 3D mesoporous silica supported MoO3 nanoparticles for the efficient photocatalytic oxidative desulfurization under visible light

A series of Mo-KIT-6 catalysts were developed to photocatalytic oxidize sulfur compounds and promote effective product separation in a photocatalytic extraction oxidative desulfurization (PEODS) system with visible light, extractant [Omim]PF6 and oxidant H2O2. Morphological and pore structure characterization showed that Mo-KIT-6 possessed significant three-dimensional mesoporous structure and large specific surface area which enhanced mass transfer effect and be provided good dispersion of active sites. Doping of Mo enhanced the light absorption and promoted the photogenerated electron hole pair separation, resulting the improvement of the ability of photocatalytic oxidation desulfurization. Among the catalysts, the 15 wt% Mo doping KIT-6 revealed the best desulfurization performance and reached 100 % sulfur removal in 25 min. The circulation experiment proved that the good circulation performance and stability of the photocatalyst within 5 cycles. Radical scavenger experiments and ESR analysis confirmed that OH and h+ played a major role in the reaction. Furthermore, a possible photocatalytic desulfurization mechanism was proposed.

A deep-insight into the relation between structure of graphene oxide-based interfacial catalyst and fuel oil desulfurization performance in Pickering emulsion

Based on the high stability, easy demulsification and formed large interphase contact area of the Pickering emulsion, its corresponding catalytic oxidative desulfurization (CODS) system has exhibited satisfactory desulfurization results and recycling performance. However, the relation between the interfacial catalyst structure and desulfurization performance in Pickering emulsion systems has rarely been reported. Herein, a stable Pickering emulsion CODS system was established using H3PW12O40 (HPW)-supported graphene oxide (GO) as an interfacial catalyst. Some important structural parameters, including catalyst size, surface porosities and wettability, were adjusted, and their effect on desulfurization performance was analysed in detail. Additionally, the reaction conditions, selectivity and recyclability of the studied system were systematically evaluated. The small catalyst size and high surface porosities could facilitate mass reaction transfer to improve desulfurization performance, but the effect of wettability was most prominent. The Pickering emulsion formed by the amphiphilic catalyst exhibited the optimum distribution state of emulsion droplets with an enlarged interphase contact area. After the optimized design of the catalyst structure, ultradeep fuel oil desulfurization was achieved under mild conditions without stirring. This work provides a useful reference to further mine the mechanism behind the improvement of desulfurization performance in Pickering emulsion systems.

High-entropy zeolitic imidazolate framework for efficient oxidative desulfurization of diesel fuel: Towards complete sulfur removal and valuable sulfone production

Diesel fuel contains a significant amount of aromatic sulfur compounds, which are pollutants and conventionally subjected to hydrodesulfurization to generate low-value hydrogen sulfide for removal. However, these aromatic sulfur compounds possess high economic value and exhibit crucial applications. In this study, we successfully synthesized a high-entropy zeolitic imidazolate framework (HE-ZIF) with a high specific surface area and exposed active sites via a mechanochemistry-assisted strategy. The utilization of HE-ZIF in an oxidative desulfurization system (ODS) with oxygen (O2) allows for the direct catalytic oxidation of sulfides, including dibenzothiophene (DBT) in diesel fuel. This process yields DBT to dibenzothiophene sulfone (DBTO2), a highly valuable product for achieving deep desulfurization. Additionally, the application of HE-ZIF achieves complete sulfur removal, reaching a 100% removal efficiency. Furthermore, it facilitates the recycling of high-value products, thereby enhancing the overall sustainability of the process. The investigation reveals that the synergistic effect between metals plays a crucial role in enhancing ODS performance. Furthermore, the microporous structure of HE-ZIF facilitates effective contact between the O2 oxidant and active sites. The presence of multiple metal active sites, abundant oxygen vacancies, and the microporous nature of the HE-ZIF material contribute to its ultra-high catalytic activity, thus opening new avenues for developing highly active catalysts for ODS and other catalytic reactions.

Enthalpy-driven synthesis of magnetic high entropy oxide catalyst for efficient oxidative desulfurization and high-value product recovery

High entropy metal oxides (HEOs) have shown remarkable catalytic potential owing to their multifaceted and tunable chemical composition, coupled with their exceptional thermodynamic stability. Specifically, magnetic HEOs demonstrate enhanced effectiveness in terms of catalyst separation and recovery owing to their magnetic properties. Nevertheless, current synthesis methods for magnetic HEOs often involve high-temperature conditions (typically > 1100 °C) to maximize the contribution of mixing entropy (ΔSmix) in the Gibbs equation (ΔGmix = ΔHmix - TΔSmix). Herein, unlike previous approaches, a reduction in the mixing enthalpy (ΔHmix) is proposed to result in a negative Gibbs free energy for the crystallization of HEOs. Based on this principle, a magnetic high entropy oxide, CoCrFeMnMoOx (MHEO), is successfully synthesized, at a relatively low temperature (900 °C). Notably, the MHEO catalyst demonstrated outstanding catalytic activity in the oxidative desulfurization (ODS) system utilizing O2 as the oxidant, achieving a rapid and complete sulfur removal of 100% within 3 h. Moreover, it demonstrates remarkable cycling durability, allowing for continuous operation over 20 cycles without significant loss in ODS efficiency. Furthermore, the magnetic properties of the MHEO catalyst facilitated the efficient separation and recovery of both the catalyst and high-value products. These findings offer significant insights into the design of high entropy catalysts and contribute to the advancement of sustainable green development.

Surface oxygenation of non-oxide boosts oxidation activity on polyoxometalate subunits: An enhanced Venus flytrap mechanism

Typically, the interfacial wettability of catalysts, coupled with electronic modulation, is vitally controlled through surface treatments that boost catalytic performance. Simulation of the biomimetic catalytic process, for instance, a Venus Flytrap mechanism, is deemed as one of the most prospective but particularly challenging protocols to achieve efficient redox catalysis. Herein, a green oxidative desulfurization (ODS) system was readily fabricated, which constituted a modular moiety ionic liquid ([Bmim]Br) triggered PW12O40 (BHPW) anchored on oxygenated graphitic carbon nitride (o-CN). The BHPW/o-CN activates the reaction at 50 °C and is almost two times higher activity than that of BHPW/CN, combined ultrastability with handy synthetic availability for the deep oxidation of carbon–sulfur (C–S) bonds. Oxygen content serves as a descriptor for the catalytic performance. We demonstrate through mimicking CS2- and thiophene-TPD that the adsorption and pre-activation of C–S bonds on the hydrophilic CN surface are critically important for proceeding ODS reaction. Further, systematic characterization containing FT-IR, XPS, and UV–vis indicates the nature of the electron acceptor raised by the oxygen moieties for a plausible mechanism of C–S bonds and spilling to reactive centers. 1H NMR and H–D isotopic exchange analysis confirm the transfer of a proton from HPW to protonated [Bmim]– functional groups triggering the active sites for C–S bonds oxidation. Additionally, density functional calculation revealed the electronic modification of the CN properties shows conclusive activation and synergistic electron transfer mechanism for C–S. The catalyst realizes deep ODS of real diesel at 70 °C with negligible decay in successive cycles. Importantly, the extension of this protocol to other non-oxide (boron nitride) and active phases (molybdenum oxide and polyoxometalates) gives to the present widespread versatility and applicability.

Heteropolyacid Ionic Liquid-Based MCF: An Efficient Heterogeneous Catalyst for Oxidative Desulfurization of Fuel.

A new type of catalyst was synthesized by immobilizing heteropolyacid on ionic liquid-modified mesostructured cellular silica foam (denoted as MCF) and applied to the oxidative desulfurization of fuel. The surface morphology and structure of the catalyst were characterized by XRD, TEM, N2 adsorption-desorption, FT-IR, EDS and XPS analysis. The catalyst exhibited good stability and desulfurization for various sulfur-containing compounds in oxidative desulfurization. Heteropolyacid ionic liquid-based MCF solved the shortage of the amount of ionic liquid and difficult separation in the process of oxidative desulfurization. Meanwhile, MCF had a special three-dimensional structure that was not only highly conducive to mass transfer but also greatly increased catalytic active sites and significantly improved catalytic efficiency. Accordingly, the prepared catalyst of 1-butyl-3-methyl imidazolium phosphomolybdic acid-based MCF (denoted as [BMIM]3PMo12O40-based MCF) exhibited high desulfurization activity in an oxidative desulfurization system. The removal of dibenzothiophene could achieve levels of 100% in 90 min. Additionally, four sulfur-containing compounds could be removed completely under mild conditions. Due to the stability of the structure, sulfur removal efficiency still reached 99.8% after the catalyst was recycled six times.

Extractive–Oxidative Desulfurization of Real and Model Gasoline Using (gly)3H[SiW12O40]⊂CoFe2O4 as a Recoverable and Efficient Nanocatalyst

For manufacturing of clean gasoline with a lower S content (e.g., S <10 ppm), glycine-modified polyoxotungstate ((gly)3H[SiW12O40]) was immobilized on cobalt ferrite (CoFe2O4) nanoceramics via the sol–gel method and employed as an efficient recyclable nanocatalyst in an extractive–oxidative desulfurization (EODS) system. The synthesized (gly)3H[SiW12O40]⊂CoFe2O4 nanocatalyst was characterized using Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), scanning electron microscopy (SEM), and energy dispersive spectroscopy (EDS) techniques. The optimum conditions for the reaction are given as follows: 50 mL of model and real gasoline, 0.10 g of (gly)3H[SiW12O40]⊂CoFe2O4 nanocatalyst, 60 min reaction time, 35 °C reaction temperature, 3 mL of AcOH/H2O2 (V/V ratio of 1:2) as an oxidant system, and 10 mL of CH3CN solvent as an extractant. Based on optimization results under the mentioned conditions and the proposed EODS system, the removal efficiency (%) of the model fuel utilizing the (gly)3H[SiW12O40]⊂CoFe2O4 nanocatalyst can reach 98% with stable reusability up to five times without a noticeable decrease in its catalytic activity. Correspondingly, 0.4986 ppm S content in real gasoline could decline to 0.0145 ppm with a removal yield of 96% under identical conditions. Also, the kinetics of the EODS reactions was found to be pseudo-first order, and the EODS mechanism was put forward through the generation of a peroxometalate intermediate complex with phase transfer properties. The present research shows that liquid fuels can be purified into ultralow-sulfur fuels through highly oxidative desulfurization via the (gly)3H[SiW12O40]⊂CoFe2O4 nanocatalyst after the EODS process.

Efficient Removal of Dibenzothiophene (DBT) over WO3–Mo–Al Catalysts in the Extractive Catalytic Oxidative Desulfurization (ECODS) System

Efficient Removal of Dibenzothiophene (DBT) over WO3–Mo–Al Catalysts in the Extractive Catalytic Oxidative Desulfurization (ECODS) System

Preparation of cobalt-containing polyvinylimidazole ionic liquid catalyst and coupling with persulfate for room-temperature ultra-deep desulfurization

Poly-ionic liquid catalyst has both the advantages of ionic liquid and polymer, and overcomes the poor fluidity of ionic liquid, so it has become one of the hot spots in catalytic oxidative desulfurization. A polyvinyl-3-butylimidazolium cobalt chloride salt (poly-[BVIM][CoCl3]) ionic liquid catalyst was prepared and characterized. When coupled with potassium monopersulfate (PMS), the catalyst formed a catalytic oxidative desulfurization system. The results showed that the prepared poly-[BVIM][CoCl3] system had a microsphere morphology with a diameter of 28 μm, and the interior structure was a mesoporous structure formed via the self-assembly of two-dimensional thin-layered nanowires with a carbon skeleton width of 20 nm. The specific surface area was 10.54 m2·g−1, the pore volume was 0.029 cc·g−1, and the average pore diameter was 3.5 nm. The optimum experimental conditions were: a catalyst dosage of 20 mg, 0.4 g of PMS (20 %) as oxidant, a reaction temperature of 20 °C, 2 g of acetonitrile as extractant, simulated sulfur-containing oil with dibenzothiophene (DBT) concentration of 500 ppm, and an initial sulfur content of 6 g. After 20 min, the sulfur removal reached more than 99 % and remained over 90 % even after the catalyst was recycled five times. The desulfurization sequence for different organosulfur compounds was DBT greater than 4,6-dimethyl dibenzothiophene (4,6-DMDBT) > benzothiophene (BT). The main desulfurization product was determined to be DBTO2 by GC–MS analysis, and the speculated desulfurization mechanism was that Co(II) catalyzed PMS to form ·SO4−, which then oxidized the target molecules. The extraction-catalytic-oxidative desulfurization kinetic was established and verified that the desulfurization process accorded with zero-order reaction kinetics. The reaction rate constant (kp) for the production of ·SO4− was estimated to be 4.24 × 10−9 ppm−1·min−1.

Oxidative Desulfurization of Real High-Sulfur Diesel Using Dicarboxylic Acid/H2O2 System

From the perspective of pollution, economics, and product quality, it is very important to find an efficient way to minimize the sulfur content of petroleum products such as gasoline and diesel. In this work, an effective, inexpensive, and simple oxidative desulfurization system based on hydrogen peroxide activation by three dicarboxylic acids which have different carbon numbers (i.e., malonic acid, succinic acid, and glutaric acid) was utilized for the desulfurization of a real diesel sample with high organic sulfur-containing compounds. The desulfurization process was based on the oxidation of sulfur compounds in diesel fuel to the corresponding sulfones followed by acetonitrile extraction of the sulfones. To select the optimal experimental conditions, the effects of several parameters, including temperature, catalyst H2O2 dosages, and treatment time, were investigated. The results showed that the developed system was effective in desulfurizing real diesel fuel with high sulfur content. With an initial total sulfur content of about 8104 mg/L, the desulfurization rate from the diesel sample reached more than 90.9, 88.9, and 93%, using malonic acid, succinic acid, and glutaric acid, respectively. The optimum parameters such as reaction temperature, reaction time, H2O2 (50 w/w%), and carboxylic acid dosage for oxidative desulfurization were determined to be 95 °C, 6 h, 10 mL, and 0.6 g, respectively. The conversion of refractory sulfur compounds into extractable sulfone forms was verified using gas chromatography. Moreover, the kinetic study confirmed that the designed reaction system follows the pseudo-first-order kinetic model.

Bmim]FeCl4 Efficient Catalytic Oxidative Removal of H2S by Cu2+ Synergistic Reinforcement

AbstractAn iron/copper bimetallic catalytic oxidation desulfurization system was constituted by adding N‐methyl pyrrolidone (NMP) and CuCl2 aqueous solution to an iron‐based ionic liquid (Fe‐IL) for the removal of hydrogen sulfide from industrial gas streams. The desulfurizer and its sulfur products were characterized using Fourier transform infrared spectroscopy (FT‐IR), thermogravimetric analysis (TGA), and X‐ray diffraction (XRD). Static desulfurization experiments were conducted to investigate the absorption pattern of the system for H2S. The addition of NMP and water effectively reduced the acidity and viscosity of the system and improved the gas‐liquid mass transfer efficiency. The introduction of CuCl2 increased the oxidation potential of the solution and enabled Fe3+ to efficiently catalyze the oxidation of H2S to produce monomeric S. The synergistic catalytic oxidation between Fe3+/Cu2+ is the main reason why the system can maintain a high degree of purification over a long period.

A novel photocatalytic and photoelectrocatalytic system for oxidative desulfurization of model fuel using BiVO4@HKUST-1 composite in powder and deposited on fluorine-doped tin oxide

In this study, photocatalytic oxidative desulfurization (PODS), as well as a photoelectrocatalytic oxidative desulfurization (PEODS) process was used for ultra-desulfurization of a model fuel using BiVO4@HKUST-1 composite as the catalyst in powder and deposited form on a fluorine tin oxide glass. Accordingly, the metal–organic framework HKUST-1 was synthesized and modified by the addition of BiVO4 to form the BiVO4@HKUST-1 photocatalyst. The composite, as well as pristine BiVO4 and HKSUT-1 samples were used for oxidative desulfurization under catalytic, photocatalytic, and eletrophotocatalytic conditions. The best results were observed for the BiVO4@HKUST-1 composite under photocatalytic desulfurization. The effect of different parameters such as reaction time, temperature, oxidizing agent, extractant solvent, catalyst amount, and solvents was investigated. Under optimal conditions, the dibenzothiophene (DBT) removal reached 95% in the PODS system. In comparison between photocatalytic and photoelectrocatalytic systems, PEODS gave the same results at the lower time and lower amounts of oxidant and catalyst. The catalyst could be recycled and reused six times without a significant change in DBT removal.

Cobalt-based sandwich-type polyoxometalate supported on amino-silane decorated magnetic graphene oxide: A recoverable catalyst for extractive-catalytic oxidative desulfurization of model oil

In order to produce ultra-low sulfur fuel, a sandwich-type polyoxometalate (K10[Co4(H2O)2(PW9O34)2]10- (Co4-POM) was covalently immobilized on amino-modified magnetic graphene oxide, and employed as a novel heterogeneous catalyst in an extractive- catalytic oxidative desulfurization system (ECODS). The (Co4-POM@APTES-(Fe3O4/GO)) nanocomposites with various Co4-POM content were prepared. The obtained samples were characterized by XRD, FT-IR, SEM, EDX, N2 adsorption, and VSM techniques. Meanwhile, the effects of Co4-POM load percentage, reaction temperature, catalyst dosage, and H2O2/DBT molar ratio on desulfurization efficiency of the prepared catalyst were investigated. The highest catalytic activity was observed for the sample with 30 wt% Co4-POM content. Dibenzothiophene (DBT) could be completely removed within at 50 ℃ using 4 g catalyst L−1 fuel, and H2O2/DBT molar ratio of 4. In addition, BT and 4,6-DMDBT could be completely removed under the optimized conditions, which suggested a promising prospect of the catalyst for industrial applications. The nanocomposite could be easily separated and reused by utilizing an external magnetic field without any substantial decline in its catalytic activity even after five runs. The kinetic data were fitted to a pseudo-first-order model. Finally, a reaction mechanism for the catalytic oxidation of DBT in the presence of Co4-POM@APTES-(Fe3O4/GO) was proposed.

Bio-inspired strategy to enhance catalytic oxidative desulfurization by O-bridged diiron perfluorophthalocyanine axially coordinated with 4-mercaptopyridine

Developing efficient and environmentally friendly catalytic system is significant for the removal of sulfide in fuel. O-bridged diiron perfluorophthalocyanine/4-mercaptopyridine (FePcF16-O-FePcF16/4-Mpy) as a novel composite catalyst was designed and prepared by axial coordination. The catalyst characterization was conducted through ultraviolet–visible spectroscopy, fourier transform infrared spectroscopy, X-ray diffractometry, electrospray ionization–mass spectrometry and density-functional theory technology. A high-efficient extraction oxidative desulfurization system is composed of hydrogen peroxide (H2O2), the mixture of ethanol and water and FePcF16-O-FePcF16/4-Mpy. Notably, the coordination of 4-Mpy greatly enhanced the catalytic activity of FePcF16-O-FePcF16, 99.4% of the desulfurization rate was achieved in 20 min at 30 °C. The catalyst system was cycled 8 times without significantly reducing the removal of dibenzothiophene. Electron paramagnetic resonance and gas chromatography–mass spectroscopy proved the high-valent iron-oxo intermediates were the main active substances in the FePcF16-O-FePcF16/4-Mpy/H2O2 system, and the pathway of catalytic oxidation DBT was proposed. This work provided useful insights to select suitable ligands to improve the activity of metal phthalocyanine, and offered a novel idea for the construction of efficient oxidative desulfurization system.

Hausmannite Mn3O4 functionalized graphene Oxide-NaClO system for oxidative desulfurization and denitrogenation of fuel oils

Herein, Hausmannite Manganese oxides nanocubes (Mn3O4) deposited on graphene oxide (GO) nanosheets were synthesized and composited together as Mn3O4/GO via in-situ on pot hydrothermal technique. To get the morphological and electronic insights, synthesized materials were analyzed via six different analytical procedures including field emission scanning electron microscopy, energy dispersive X-ray elemental mapping, powdered X-ray diffraction, Brunauer-Emmett-Teller surface area, Fourier-transform infrared, and X-ray photoelectron spectroscopy techniques. Mn3O4 nano cubes were synthesized at an average cube size of 362 nm showing characteristic crystal planes and electronic distribution ratio (Mn2+/Mn3+::1:2) of a typical Hausmannite Mn3O4 structure. Whereas, the synthesized GO sheets (average layer thickness of 451.1 nm) were well consistent with Lerf and Klinowski model and exhibited the characteristic functionalities. Results suggested that incorporation of Mn3O4 (average particle size of 275.3 nm) at the B-sites of GO enhanced the active surface area by 65 % (22.9 m2.g−1) and surface functionalities of the composite, which predicted excellent catalytic response from the Mn3O4/GO composite. ODS and ODN tests were performed using different substrates of sulfur and nitrogen compounds, where Mn3O4/GO-NaClO system removed 2200 ppm DBT and Py in 2 min at 25 °C. O/S and O/N ratio of 4 and 0.04 g/15 mL. Whereas, the overall activity order followed as: DBT (100 %) > 4,6-DMDBT (89 %) > BT (85 %), and: pyridine (100 %) > indole (83 %) > carbazole (81 %). Recyclability and catalyst stability was recorded for 6th consecutive runs with minimal loss in the activity (100–92 %). High efficiency of the Mn3O4/GO-NaClO system was accredited to the ClO− and its propensity of selective synergism with Mn+2/Mn+3, which the resulted active •O2– that oxidized sulfur and nitrogen species in 2 min at 25 °C. Thus, an alternative route could be obtained for the ultra-fast and highly efficient, environment friendly and cost-effective oxidative desulfurization and denitrogenation of fuel oils.

Construction of H6PW9V3O40@rht‐MOF‐1 for deep oxidative desulfurization of fuel oil

AbstractDeep desulfurization is impending for environmental conservation by way of reducing supplied emissions from fuel oil. Developing new and effective catalysts on deep desulfurization is still a great changeling. In this piece of work, a series of three H3+nPW(12‐n)VnO40@rht‐MOF‐1 have been synthesized by one‐pot self‐assembly hydrothermal reaction of CuCl2·2H2O and 5‐tetrazolyl isophthalic acid (H3TZI) with three H3+nPW(12‐n)VnO40 (polyoxometalates [POMs]), respectively. X‐ray crystallographic analysis reveals that the POMs have been successfully encapsulated in the cages of rht‐MOF‐1. The affording complex 3, as heterogeneous catalyst, is able to effectively catalyze the extraction catalytic oxidation desulfurization system (ECODS) of model oil and real fuel oil under mild reaction conditions. The remarkable encapsulation of POMs in rht‐MOF‐1 resulted in the heterogeneous catalysis, enabling it to be recycled in the system. The reaction kinetics has been investigated, and the redial reaction mechanism has been verified by electron paramagnetic resonance (EPR) analysis and radical quenching experiments. This approach provides an easy and effective route on developing heterogeneous catalysts that could be applied in the deep ECODS of fuel oil.

Oxidative desulfurization of fuel oil catalyzed by a carbon nitride supported phosphotungstic acid based dicationic ionic liquid

A novel supported bis-imidazole phosphotungstate ionic liquid x% [C2(MIM)2]PW12O40/g-C3N4 was prepared and used as a catalyst in a catalytic oxidative desulfurization system with H2O2 as the oxidant.

Ultrasound-assisted extractive/oxidative desulfurization of oil using environmentally benign trihexyl tetradecyl phosphonium chloride

A phosphonium-based ionic liquid (PIL) trihexyl tetradecyl phosphonium chloride ([THTDP]Cl) was applied as an effective catalyst/extractant for the desulfurization of model oil (MO) as well as base oil. In the ultrasound-assisted extractive/oxidative desulfurization (UEODS) process, a liquid–liquid catalytic oxidative desulfurization system containing MO/base oil, hydrogen peroxide, and PIL was observed at 30 °C and maximum sulfur removal of 98.67% was obtained. After completion of the reaction, PIL was separated from MO. The PIL was then regenerated and recycled 5 times without a significant decrease in efficiency. The influence of UAODS of MO containing dibenzothiophene (DBT), benzothiophene (BT), thiophene (T), and 3-methyl thiophene (3-MT) was also observed, which shows fast oxidative desulfurization capability under ultrasound irradiation. The oxidation reactivity of sulfur compounds follows the order of DBT > BT > TH > 3-MT at the DBT optimized conditions. The quantity of PIL, H2O2/DBT mole ratio, oxidation temperature, and time all played significant roles in sulfur removal, which were also analyzed in detail to optimize the reaction conditions during UEODS. The density functional theory study was carried out to understand the exact mechanism responsible for the effective interaction between PIL and sulfur compounds. The desulfurization of base oil was also carried out to check the feasibility of the UEODS process and achieved 74.98% desulfurization efficiency. These results proved the efficacy of the UEODS process for industrial application.