Extractive Oxidative Desulfurization Research Articles

Kinetic modeling and mechanistic evaluation of oxidative-extractive desulfurization of actual diesel fuel using ionic liquids: Engineering aspects with parametric study

In the present research, oxidative-extractive desulfurization (OEDS) of actual diesel fuel is executed by utilizing coordinated ionic liquid (IL), and a novel kinetic model is put forward to explain the OEDS process. A series of ILs synthesized by the coordination of three solvents [N,N dimethyl-formamide (DMF), N-methyl-pyrrolidone and dimethyl sulfoxide] with three salts (CaCl2, ZnCl2, and MgCl2) were tested for OEDS of diesel fuel. The best-performing IL i.e., DMF.ZnCl2 was utilized to investigate the impact of oxidant-to-sulfur (O/S) molar ratio, diesel-to-IL volume ratio, temperature, and time. Thermal analysis; thermogravimetric analysis-differential thermogravimetric analysis (TGA-DTG), and differential scanning calorimetry (DSC) were conducted to understand their thermal stability. 1HNMR was used to examine the interactions between their components. To understand the mechanism of removal, Fourier transform infrared (FTIR) spectra and UV–visible spectra of IL were studied. The kinetic model used in the present investigation presumed the extraction of non-oxidized as well as oxidized sulfur compounds. Compared to earlier reported models, the present novel kinetic model provided an improved representation of the kinetic data. At the optimized conditions (O/S ratio = 6:1, diesel to IL volume ratio = 3:1, and temperature = 50 °C), a maximum of 86 % sulfur removal was estimated from actual diesel fuel.

SBA-15 Type Mesoporous Silica Modified with Vanadium as a Catalyst for Oxidative and Extractive Oxidative Desulfurization Processes.

One of the current challenges is the reduction of sulfur emitted into the atmosphere, usually in the form of sulfur oxides generated by fossil fuel combustion. To achieve this goal, the sulfur content should be reduced in fuel. In this context, vanadium-containing materials based on SBA-15 mesoporous silica supports and two different sources of vanadium were prepared, characterized, and applied as catalysts for oxidative desulfurization (CODS) and extractive oxidative desulfurization processes (ECODSs). The novelty of this work was the comparative study of vanadium-containing materials in two desulfurization systems. The properties of the catalysts, the concentration and state of vanadium species, and their role in the catalytic process were examined by low-temperature nitrogen physisorption, XRD, UV-Vis, XPS, and chemisorption of pyridine combined with FTIR spectroscopy. The catalytic performance of the material prepared using ammonium metavanadate was superior to that of the catalyst obtained using vanadium(IV) oxide sulfate, which was explained by a higher concentration of vanadium species on the surface of the support and their lower oxidation state in the former. Both types of catalysts showed high activity and stability in the ECODS process.

Ionic Liquids as Green and Efficient Desulfurization Media Aiming at Clean Fuel.

With increasingly stringent emission limits on sulfur and sulfur-containing substances, the reduction and removal of sulfur compounds from fuels has become an urgent task. Emissions of sulfur-containing compounds pose a significant threat to the environment and human health. Ionic liquids (ILs) have attracted much attention in recent years as green solvents and functional materials, and their unique properties make them useful alternatives to conventional desulfurization organic solvents. This paper reviews the advantages and disadvantages of traditional desulfurization technologies such as hydrodesulfurization, oxidative desulfurization, biological desulfurization, adsorptive desulfurization, extractive desulfurization, etc. It focuses on the synthesis of ionic liquids and their applications in oxidative desulfurization, extractive desulfurization, extractive oxidative desulfurization, and catalytic oxidative desulfurization, and it analyzes the problems of ionic liquids that need to be solved urgently in desulfurization, looking forward to the development of sulfuric compounds as a kind of new and emerging green solvent in the field of desulfurization.

Ionic Porous Aromatic Frameworks Embedding Polyoxometalates for Heterogeneous Catalysis.

Porous aromatic frameworks (PAFs) are highly promising functional porous solids known for their feasible amenability and extraordinary stability. When the framework was modified by ionic functional groups, these ionic PAFs (iPAFs) exhibited charged channels for adsorption, separation, and catalysis. However, the surface areas of ionic porous frameworks are usually lower than that of neutral frameworks, and their synthesis is limited by specific strategies and complex modification processes. To address these challenges, an intuitive route to construct ionic porous framework with high specific surface area was proposed. Herein, a multivariate ionic porous aromatic framework (MTV-iPAFs, named PAF-270) was synthesized using readily available building units with ionic functional groups through a multivariable synthesis strategy. PAF-270 exhibited hierarchical structure with the highest specific surface area among reported imidazolium-functionalized PAFs. Utilizing its physical and chemical properties, the availability for polyoxometalate loading and heterogeneous catalysis of PAF-270 were explored. PAF-270 exhibited a high adsorption capacity up to 50 % for both H3O40PW12 (HPW) and (NH4)5H6PV8Mo4O40 (V8). HPW@PAF-270 and V8@PAF-270 exhibited excellent catalytic abilities for oleic acid esterification and extractive oxidative desulfurization, respectively. Due to the stability of PAFs, these materials also showed remarkable resistance to temperature and pH changes. Overall, these results underscore the potential application of MTV-iPAFs as versatile functional porous materials.

Confining peroxophosphomolybdate within size-matched Zr-MOFs for extractive oxidative desulfurization

Deep desulphurization of diesel is essential because the sulfides from fuel combustion can cause acid rain, respiratory diseases and corrosion of industrial equipment. Peroxophosphomolybdate (BTA)3{PO4[MoO(O2)2]4}·3H2O, marked as PMo4, was confined in size-matched Zr-MOFs (UiO-66 and UiO-67) to prepared composites for extractive oxidative desulfurization. The composites underwent comprehensive characterization, including ICP-MS, FT-IR, XRD, SEM, XPS, TG and N2 adsorption–desorption analysis. Desulfurization test was conducted with PMo4 as homogeneous catalyst, and the reaction conditions were optimized. Then, the catalytic activity of the prepared composites was compared, and the result showed that the catalyst PMo4@UiO-67 can remove 94.1 % of the sulfides in the diesel within 100 min. After 15 consecutive tests, the total removal rate of sulfides still reached 88.5 %, thanks to the narrow window of carrier UiO-67 limited the leaching of the active component PMo4.

Coupled one-pot oxidative extractive desulfurization of a model fuel catalyzed by nanostructured-ZIF-67/Biomass-derived activated carbon composite

The simultaneous oxidation and extraction of refractory sulfur compounds, such as DBT, has emerged as one of the most efficient complementary procedures for the HDS process in achieving ultradeep desulfurization of fuels. In this paper, a bio-based activated carbon (AC) obtained from the waste of date palm bark has been utilized as an abundant, green, and low-cost support for synthesizing a stable metal-organic framework, zeolitic imidazolate framework-67 (ZIF-67), on its structure to reach a novel nanocomposite catalyst (AC/ZIF-67) for the removal of DBT from a model fuel through the extractive oxidative desulfurization method. The accuracy of the AC/ZIF-67 catalyst formation was comprehensively characterized using XRD, FTIR, FESEM, BET, and TGA analytical techniques. Subsequently, the newly synthesized nanocomposite catalyst was employed efficiently for removing DBT from a toluene solution, acting as a model fuel. The impact of various operating variables, i.e. catalyst dosage, the temperature of reaction, oxidant-to-sulfur (O/S) molar ratio, contact time, initial concentration of DBT, and volume of extraction solvent on the removal efficiency has been thoroughly investigated. The results revealed that employing only 25 mg of the AC/ZIF-67 catalyst could achieve a remarkably high efficiency of around 98 % after one hour oxidation of a 25 ppm DBT solution in the presence of TBHP, followed by extraction using acetonitrile. This was achieved while maintaining a constant temperature of 60 °C and an O/S ratio of 20. The obtained results confirm the potential application of ACs for supporting MOF catalysts in various catalytic processes such as desulfurization.

Preparation of the MoO3- Fe3O4 nanocomposites for deep oxidative desulfurization of model fuel: Optimization and experimental design

In the present study, the catalytic activity of the MoO3-Fe3O4 of molybdenum oxides prepared by the impregnation method was investigated in the extractive oxidative desulfurization (EODS) process. Structural characterization of the nanocomposite catalysts was studied by XRD, N2 adsorption–desorption isotherm, FT-IR, and VSM analyses. The EODS technology was applied to remove sulfur from a model fuel (dibenzothiophene in n-octane, DBT) using H2O2 as the oxidant, acetonitrile as the extracting solvent, and MoO3-Fe3O4 as the catalysts. Among the catalysts with various loadings of MoO3 on Fe3O4 nanoparticles (3, 6, 9, 12, and 15 wt%), the catalyst with 9 wt% MoO3 demonstrated the highest performance. Subsequently, the optimal design of the experiments using response surface methodology (RSM) based on Box-Behnken design (BBD) was applied to study the effects of the independent parameters such as O/S molar ratio, reaction temperature, and catalyst dosage on sulfur removal efficiency. Optimization studies were performed, and maximum sulfur removal efficiency of 98 % was achieved under the optimal conditions of 58 °C, O/S molar ratio: 5.9, and 0.116 g of 9 wt% MoO3-Fe3O4 as catalysts. The activity of the catalyst remained unchanged after six times recycling in the EODS process. Additionally, a catalytic reaction mechanism was proposed.

Photocatalytic oxidative-extractive desulfurization of dibenzothiophene under simulated solar light with MoS2-CeO2/Al2O3-SiO2 nano photocatalyst: effect of CeO2 content

In this paper, a visible light-driven nanophotocatalyst of MoS2 with different amounts of CeO2 (0%, 8%, 16%, 24%, and 32% wt.) was impregnated on SiO2-Al2O3. The physicochemical properties of synthesized photocatalysts were investigated by XRD, FESEM, TEM, UV-Vis DRS, PL, BET-BJH, ICP-OES, EDX, and FTIR analyses. While the size of particles in all samples was in the nanoscale range, the sample with 8% wt. of CeO2 indicated the narrowest particle size distribution. UV-Vis DRS and PL analyses confirmed that adding CeO2 to the MoS2/SiO2-Al2O3 photocatalyst increased the amount of light absorption and decreased the recombination rate of charge carriers. Among CeO2-containing samples, the sample with 8% wt. of CeO2 illustrated the lowest recombination rate and the narrowest bandgap energy of 2.9 eV. The MoS2-CeO2/SiO2-Al2O3 photocatalyst with 8% wt. of CeO2 had the highest adsorption of DBT in dark conditions (29.93%), the highest photodegradation (96.9%) after 3 h of visible light irradiation and good stability after five consecutive runs. Meanwhile, total sulfur measurement indicated that using this sample and the extraction afterward, the model fuel has lost 96% of its sulfur content which confirms the excellent ability of acetonitrile-assisted extraction in gathering desulfurization products from the fuel.

Choline-based Deep Eutectic Solvent for Extractive Oxidative Desulfurization of Model Oil

One of the hardest processes encountered by petroleum refining is sulfur elimination from fuel oil. There are many traditional methods executed but they caused drawbacks such as poor selectivity of sulfur compounds and toxic raw materials. Extractive oxidative desulfurization (EODS) caught the interest of researchers due to high selectivity of sulfur compounds and great desulfurization. Currently, researchers are investigating the use of ionic liquids (ILs) as green extractant, unfortunately they are expensive. This research is proposing and comparing the use of cheap biodegradable solvents called deep eutectic solvents (DESs), as extractants in removing sulfur from fuel oil. The DESs are synthesized through a combination of choline chloride - orcinol and choline chloride - ethylene glycol, and their structure is confirmed through FTIR. Their thermal properties are characterized by DSC and TGA. Their desulfurization performance is evaluated by type of DESs, different ratios of DES and model oil, different ratios of oxidant and sulfone and various temperatures which these factors are found to influence the result. The optimum conditions are found to be at 1:1 for DES and model oil ratio, 4 for O/S ratio and temperature at 85 °C with the extraction efficiency of 99.98%. In conclusion, this DES has high potential to be the cheap green alternative to the conventional extractant for extractive oxidative desulfurization process.

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.

High efficiency extraction oxidation desulfurization of model liquid fuel catalyzed by MIL-101(Fe) supported peroxo-polyoxometalates

In this work, the encapsulating peroxo-polyoxometalate in the mesoporous of metal-organic framework (MIL-101(Fe)) to synthesize composite according to the principle of host-guest matching. The structure of the host-guest composite was analyzed by a variety of methods, and the catalytic activity for desulfurization was investigated under mild conditions. The composites combine the advantages of peroxo-polyoxometalate (high efficiency) and MIL-101(Fe) (good recyclability and high porosity), showing synergistic effect between host and guest. The sulfur-containing organic compounds in simulated liquid fuel can be almost completely removed under the catalysis of PW4@MIL-101(Fe). The catalyst PW4@MIL-101(Fe) can be reused for 10 times without prominent decrease in desulfurization activity, indicating that it has good reusability due to the confinement effect between the window size of MIL-101(Fe) and molecular size of PW4. In addition, several control experiments and electron spin resonance experiment were researched to explore the possible mechanism, and the results show that the active component in the catalyst can promote the decomposition of H2O2 into ·OH and thus accelerate the desulfurization reaction. This work discloses a facile and environmentally friendly method to prepare the "host-guest matching" catalyst with high activity and stable reusability, which provides ways for further developments in heterogeneous catalyst based on POM and MOF.

Polyoxometalates Encapsulated into Hollow Periodic Mesoporous Organosilica as Nanoreactors for Extraction Oxidation Desulfurization

In this work, the highly active polyoxometalate (PW2Mo2) with Venturello structure and its corresponding catalyst were applied in catalytic desulfurization for the first time. PW2Mo2 as an active component was effectively encapsulated in hollow periodic mesoporous organosilica (HPMOS) to form the nanoreactor PW2Mo2@HPMOS, where the central cavity and mesoporous shell facilitate mass transfer and both provide a stable place to react with organic sulfides. Desulfurization test results show that the hollow nanoreactor PW2Mo2@HPMOS can almost remove four sulfides simultaneously from diesel in 2 h under mild conditions. Besides, the nanocatalyst PW2Mo2@HPMOS can be reused and recycled for at least seven consecutive tests without any noticeable loss in performance. With the rapid development of the economy, the massive use of sulfur-containing fuel has a huge impact on the global climate. After combustion of sulfur-containing fuel, the realized SOX is an important inducement of the formation of acid rain, and the realized sulfur particle is also a major source of haze. Therefore, removing sulfur compounds from fuel is an important issue that needs to be solved immediately.

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.

Encapsulated peroxo-polyoxometalates into Fe2O3/C hybrid material carbonized from MIL-101(Fe) as efficient magnetic catalyst for desulfurization of fuel

Magnetic hybrid material dropped Fe2O3 particles in mesoporous carbon was prepared by pyrolysis of MIL-101(Fe) in the presence of nitrogen flow. Then, high activity peroxo-polyoxometallates (Bu4N)3PWxMo4-x (x = 0, 2, 4) were encapsulated into the magnetic porous carbon material Fe2O3/C through facile impregnation method to prepare magnetic supported catalysts (Bu4N)3PWxMo4-x@Fe2O3/C. The catalysts were characterized by several means and applied for extraction oxidation desulfurization (EODS) of model fuel. One synthesized catalyst, (Bu4N)3PW4@Fe2O3/C, exhibited nearly perfect catalytic activity, which could remove 99.9 % DBT in simulated fuel within 30 min at mild conditions, and it also showed good activity for other substrate sulfides including BT, 4-MDBT and 4,6-DMDBT. Furthermore, the catalyst (Bu4N)3PW4@Fe2O3/C has stable structure and good reusability, which shown removal efficiency of DBT of>90 % up to 8 cycles.

Ultrasonic Auxiliary Ozone Oxidation-Extraction Desulfurization: A Highly Efficient and Stable Process for Ultra-Deep Desulfurization.

For ultra-deep desulfurization of diesel fuel, this study applied the ultrasound-assisted catalytic ozonation process to the dibenzothiophene (DBT) removal process with four Keggin-type heteropolyacids (HPA) as catalysts and acetonitrile as extractant. Through experimental evaluations, H3PMo12O40 was found to be the most effective catalyst for the oxidative removal of DBT. Under favorable operating conditions with a temperature of 0 °C, H3PMo12O40 dosage of 2.5 wt.% of n-octane, and ultrasonic irradiation, DBT can be effectively removed from simulated diesel. Moreover, the reused catalyst exhibited good catalytic activity in recovery experiments. This desulfurization process has high potential for ultra-deep desulfurization of diesel.

Evaluation the performance of the tin (IV) oxide (SnO2) in the removal of sulfur compounds via oxidative-extractive desulfurization process for production an eco-friendly fuel

Abstract Catalysts play a vital role in petroleum and chemical reactions. Intensified concerns for cleaner air with strict environmental regulations on sulfur content in addition to meet economic requirements have generated significant interests for the development of more efficient and innovative oxidative catalysts recently. In this study, a novel homemade nano catalyst (manganese oxide (MnO2) over tin (IV) oxide (SnO2)) was used for the first time as an effective catalyst in removing dibenzothiophene (DBT) from kerosene fuel using hydrogen peroxide (H2O2) as oxidant in catalytic oxidative-extractive desulfurization process (OEDS). The catalyst was prepared by impregnation method with various amount of MnO2 loaded on SnO2. The oxidation step was carried out at different operating parameters such as reaction temperature and reaction time in batch reactor. The extractive desulfurization step was performed by using acetonitrile as solvent under several operating conditions (agitation speed and mixing time). The activity of MnO2/SnO2 catalyst in removing various sulfur compounds from kerosene fuel at the best operating conditions was investigated in this work. The results of the catalyst characterization proved that a high dispersion of MnO2 over the SnO2 was obtained. The experiments showed that the highest DBT and various sulfur compounds removal efficiency from kerosene fuel under the best operating conditions (oxidation: 5% MnO2/SnO2, reaction temperature of 75 °C, and reaction time of 100 min, extraction: acetonitrile, agitation speed of 900 rpm, and mixing time of 30 min) via the catalytic oxidative-extractive desulfurization process was 92.4 and 91.2%, respectively. Also, the MnO2/SnO2 catalyst activity was studied after six consecutive oxidation cycles at the best operating conditions, and the catalyst prove satisfactory stability in terms of sulfur compounds removal. After that, the spent catalyst were regenerated by utilizing different solvents (methanol, ethanol and iso-octane), and the experimental data explained that iso-octane achieved highest regeneration efficiency.

Oxidation-extraction desulfurization of fuel with a novel green acidic deep eutectic solvent system

Deep eutectic solvents (DESs) have important application prospects in fuel desulfurization. A novel dual Brønsted acidic DES was proposed and successfully synthesized for one-pot oxidation-extraction desulfurization process, in which a green and harmless choline chloride (ChCl) was used as hydrogen bond acceptor, p-toluenesulfonic acid (TsOH) and oxalic acid (OA) were used as hydrogen bond donors to provide acidic groups. The results showed that the new DESs (ChCl/2TsOH/0.2OA) had the excellent desulfurization efficiency due to the strong acidity based on the synergistic effect between the two acidic groups. The content of benzothiophene (BT), dibenzothiophene (DBT), and 4,6-dimethyldibenzothiophene (4,6-DMDBT) could be reduced to 8.82 ppm (120 min), 1.23 ppm (90 min), and 7.75 ppm (90 min), respectively. Electron spin resonance and radical capture experiments showed that superoxide radicals (·O2–) were the main oxidizing agents. The possible oxidation-extraction pathway was that DBT was extracted from oil phase into DES phase, and the DES was converted to peroxy acid in the presence of ·O2–, then the extracted DBT in DES phase was oxidized to high polar sulfone. It can be regenerated and recycled by simple water washing. To improve dispersion and treatment efficiency, reduce the amount of DESs, the viscosity of DESs was adjusted by using sulfolane as the dilute, which could significantly reduce the operation time and enhance the desulfurization effect. The content of BT, DBT, and 4,6-DMDBT could be reduced to 12.20, 2.21, 7.38 ppm only need 45, 5, and 15 min, correspondingly. The novel green DES can provide theoretical support and technical guidance for deep fuel desulfurization.

Teknoekonomi Penyingkiran Senyawa Sulfur dari Kondensat Gas Alam dengan Metode Desulfurisasi Oksidatif-Ekstraktif

In the oil and gas production process, apart from hydrocarbons, a number of impurities are produced, including CO2 and sulfur in various concentrations, depending on the conditions and characteristics of the reservoir and the location where the oil and gas is located. To process sulfur removal from condensate, the common technology is HDS (Hydrodesulfurization). However, with process requirements such as high temperature, pressure, and intensive hydrogen consumption, an alternative technology is needed for this desulfurization. One of them is oxidative-extractive desulfurization. Technical and economic evaluations to determine the feasibility of applying on an industrial scale need to be studied further. The study of oxidative-extractive desulfurization process of sulfur compounds (represented as dibenzothiophene, DBT) was carried out using H2O2/formic acid as oxidizing agent and catalyst, as well as extraction with DMF. For a capacity of 1000 bpd of condensate with 1%-wt sulfur, desulfurization was successfully carried out with sulfur removal of 96.55% and condensate recovery of 99.41%. A processing fee of 9.14 USD/barrel is required, of which 84% is required for chemicals. The alternative process configuration for DMF recovery succeeded in reducing chemical costs by 35.5% and reducing total processing costs by 27.0% to 6.67 USD/barrel. In this alternative process configuration, 95.80% sulfur removal was achieved with condensate recovery of 99.21%.

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.

Extractive oxidative desulfurization of fuels using choline chloride and tetraethylene glycol-based eutectic solvent

Due to ever-increasing environmental problems, special attention has been paid to removing the organosulfur compounds present in transportation fuel. Therefore, to minimize the adverse effects of automotive exhaust emissions, sulfur level in motor fuels is minimized. Nowadays, DESs have become eco-friendly solvents due to their significant properties such as low toxicity, low volatility, etc. Thus, found attractive toward extraction process also. In this study, a series of DES using CHCl, MTTPBr, TEAC as HBA and PYG, EG, and TetEG as HBD in the different mole ratios were synthesized and investigated their extraction performance for sulfur in model and diesel fuels. Densities, viscosity & FTIR spectra of synthesized DESs were recorded. ODS was also performed for diesel. Results concluded that among all the synthesized DESs, [CHCl][TetEG](1:5) worked better for the desulfurization of fuels. In a single-stage, around 43% extraction efficiency was achieved for model sulfur compounds using [CHCl][TetEG](1:5), which can be enhanced up to 86% using successive extraction stages at low-temperature 30 °C. However, around 34% and 29%, respectively, extraction efficiency was achieved for diesel due to their complex nature. While on oxidation of diesel, it was increased up to 52% and 43% respectively in one single stage at a low-temperature 30 °C.