Dibenzothiophene Sulfone Research Articles

Desulfurization of dibenzothiophene and dibenzothiophene sulfone via Suzuki–Miyaura type reaction: Direct access to o-terphenyls and polyphenyl derivatives

The reactivity of dibenzothiophene (DBT) or dibenzothiophene sulfone (DBTO2) with a variety of phenylboronic acids was mediated by the nickel precursor [Ni(dippe)Cl2] in the presence of a base. The reaction was performed under relatively mild conditions (70–100 °C), in aqueous media. The study of the reactivity revealed the role of water as a hydrogen source and showed a competition between the desulfurization of the corresponding substrates via a hydrodesulfurization (HDS) or by a hydrodesulfurative cross-coupling (HDSCC) reaction. Furthermore, in the absence of water sulfur-free poly-phenylic compounds were obtained in good yields as a result of a Suzuki–Miyaura type reaction, being the main product in most of the cases the corresponding o-terphenyl derivative, these products are valuable building blocks in the synthesis of more complex materials.

Oxidative removal of dibenzothiophene and related sulfur compounds from fuel oils under pressurized oxygen at room temperature with hydrogen peroxide and a phosphorus-free catalyst: sodium decatungstate

We investigated the removal of dibenzothiophene (DBT) and related compounds, 4-methyldibenzothiophene (4-MeDBT), 4,6-dimethyldibenzothiophene (4,6-DMeDBT), 2,8-dimethyldibenzothiophene (2,8-DMeDBT), and 1-benzothiophene (1-BT) from several oil media at room temperature under pressurized O2 (0.6 MPa) by means of a three-phase reaction system consisting of the oil phase, an aqueous phase containing the phosphorus-free polyoxotungstate catalyst Na4W10O32·8H2O, H2O2, and tetraoctylammonium bromide, and the gas phase. Under conditions in which the initial DBT concentration in octane was 10.1 mM, the desulfurization ratio reached 87% after reaction for 6.5 h. The sulfur atoms in the initial DBT were well accounted for by the sulfur atoms in the residual DBT, the dibenzothiophene sulfone and dibenzothiophene 5-oxide in the octane phase, and the dibenzothiophene sulfone that precipitated. Prolonged reaction time to 18 h resulted in 92% desulfurization. The desulfurization of octane decreased in the order 2,8-DMeDBT ~ DBT > 4-MeDBT >1-BT ~ 4,6-DMeDBT. Light oil and kerosene could also be desulfurized efficiently: after reaction for 6.5 h, the desulfurization ratios reached 77 and 78% for light oil and kerosene, respectively.

Decomposition of Oxidized Sulfur-Containing Components of Crude Oil and Petrochemicals Under Conditions of Nanoheterogeneous Catalysis

The catalytic decomposition of dibenzothiophene sulfone is studied in the presence of nanosized iron(III) oxide with an average particle diameter of 10–12 nm; it is synthesized by the thermolysis of iron(III) acetylacetonate in the medium of diphenyl ether. The optimum conditions of the process are ascertained by varying the temperature and time of the reaction and the concentration of the nanosized catalyst. It is shown that the oxidative desulfurization of crude oil and petrochemicals may occur with the oxidized sulfur-containing components being decomposed under mild conditions in the presence of nanosized iron(III) oxide at the second stage. In some cases, the degree of desulfurization is above 80%.

Hydroconversion of Oxidation Products of Sulfur-Containing Aromatic Compounds

Hydroconversion of benzo- and dibenzothiophene sulfone on a Ni–Mo sulfide catalyst based on mesoporous aluminosilicate Al-HMS and on unsupported catalysts prepared in situ in the course of decomposition of poorly soluble precursors (molybdenum hexacarbonyl, nickel naphthenate) was studied. Hydrogenation of sulfones was perfpormed at 250, 340, and 380°С and elevated СО pressure in the presence of water ensuring in situ generation of hydrogen via water-gas shift reaction.

Deep desulfurization of fuels with cobalt chloride-choline chloride/polyethylene glycol metal deep eutectic solvents

Deep eutectic solvents (DESs) are receiving increasing attention as ionic liquid analogues because of their environmentally friendly and very low-price characteristics. In this study, metal-based deep eutectic solvents (MDESs) were synthesized by combining cobalt chloride (CoCl2), a hydrogen bond acceptor (HBA) such as choline chloride (ChCl), and hydrogen bond donors (HBDs) such as polyethylene glycol (PEG-200), ethylene glycol (EG), glycerol (GL), and propionic acid (Pr). The MDESs were used for the extractive catalytic oxidative desulfurization (ECODS) of fuels. Solid peroxymonosulfate (PMS) was selected as an oxidant over common ECODS oxidants such as liquid hydrogen peroxide because the former is cheaper, more stable, and less corrosive. The MDESs played dual roles (i.e., extractant and catalyst) during the ECODS process. One of the MDESs prepared (CoCl2-ChCl/2PEG) showed fast reaction rates with nearly 100% dibenzothiophene removal under the optimal conditions (6 g of model oil with an initial sulfur content of 500 ppm, 0.9 g of PMS solution, 2 g of CoCl2-ChCl/2PEG, 20 °C, and 60 min). The DESs prepared showed an outstanding recycling performance after 6 cycles without a significant decrease in activity. In the ECODS system, the reactivity of the three sulfur substrates studied followed the order: dibenzothiophene (DBT) > 4,6-dimethyldibenzothiphene (4,6-DMDBT) > benzothiophene (BT). In the case of the HBDs, the desulfurization efficiencies followed the sequence: PEG-200 > Pr > EG > GL. The oxidative product was dibenzothiophene sulfone (DBTO2).

Investigating the Kinetics, Mechanism, and Reaction Pathway of a Biodesulfurizing Enzyme from Rhodococcus erythropolis, Dibenzothiophene Monooxygenase

Fossil fuel combustion is a major source of sulfur dioxide, dangerous to respiratory health and the environment. Sulfur removal from fossil fuels eases these effects, however, the current method, hydrodesulfurization, requires costly high temperatures and pressures. The bacterial species Rhodococcus erythropolis uses a four‐step enzymatic process, known as biodesulfurization, to remove sulfur in fuel compounds. The first enzyme in the pathway, dibenzothiophene monooxygenase (DszC), uses reduced flavin and molecular oxygen to generate a flavin intermediate that oxygenates its substrate, dibenzothiophene, to dibenzothiophene sulfoxide, then dibenzothiophene sulfone. Our objectives are to understand DszC's enzymatic mechanism and steps of the catalytic pathway to engineer DszC to accept various organosulfur compounds and increase catalytic efficiency. Towards our goals, we have purified active DszC; determined steady‐state kinetic parameters of DszC as a function of dibenzothiophene, dibenzothiophene sulfoxide, and flavin substrates; performed steady‐state experiments to describe DszC's enzymatic mechanism; and used transient‐state kinetics to ascertain the effects of dibenzothiophene and age times on flavin binding. Using affinity chromatography, we purified DszC at 0.5 gram/liter of culture in its native tetrameric state. Reverse‐phase HPLC experiments showed DszC had faster product turnover using dibenzothiophene sulfoxide as substrate versus dibenzothiophene (11.8 × 10−3 s−1 vs. 4.84 × 10−3 s−1). HPLC assays also demonstrated that having equimolar flavin and DszC resulted in a faster turnover rate than using excess flavin (4.84 × 10−3 s−1 vs. 1.49 × 10−3 s−1). Varying flavin and dibenzothiophene concentrations under steady‐state conditions indicated DszC likely forms a ternary complex with the flavin intermediate and dibenzothiophene to facilitate oxygenation. Using stopped‐flow spectrophotometry, we observed fast flavin binding (<1 second) and that having equimolar dibenzothiophene and DszC increased intermediate formation rates. Dibenzothiophene pre‐incubation with DszC, however, decreased intermediate formation rates, suggesting reduced flavin is the initial substrate to bind to DszC. These results provided us kinetic and mechanistic insights towards understanding the full catalytic pathway of DszC to support our goals of engineering a robust and efficient DszC enzyme for industrial applications.Support or Funding InformationNational Institute of Health (SCORE 5SC2AI109500)Research Corporation CCSA 22672MARC/RISE Program (NIH Grant Number 2R25GM063787‐10)CSUPERB New Investigator GrantThis abstract is from the Experimental Biology 2018 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.

Initial Characterization of DszA, a Monooxygenase from the Rhodococcus Biodesulfurization Pathway

Sulfur dioxide is a pollutant found in our atmosphere that affects our health, environment, and economy. The most common source of sulfur dioxide pollution is the combustion of fossil fuels. To control pollution, it is important to remove sulfur from these fuels. The current sulfur removal method, hydrodesulfurization, is inefficient because it cannot remove sulfur from refractory organosulfur compounds. There are multiple bacterial species, including Rhodococcus erythropolis, that can remove sulfur from aromatic compounds, such as dibenzothiophene (DBT). DBT is a major organosulfur compound found in crude petroleum. The biodesulfurization pathway in Rhodococcus erythropolis can successfully remove sulfur from DBT to produce hydroxybiphenyl and sulfite. Our study focuses on an enzyme in this biodesulfurization pathway, the DBT sulfone monooxygenase, DszA that catalyzes the conversion of DBT sulfone to 2′‐hydroxybiphenyl 2‐sulfinate. Our goal was to obtain pure, active, and soluble protein for initial characterization of DszA. Thus far, we have determined the optimal parameters for expression of DszA by various expression and pH trials. The optimal temperature and pH for enzyme expression were 18°C and 7.5, respectively. DszA was successfully overexpressed in Escherichia coli and will be ready to purify by nickel affinity chromatography to take advantage of the His tag found in our protein. Our future steps are to apply steady‐state and transient‐kinetics to determine the kinetic parameters and study the mechanism of this important reaction step in the Rhodococcus biodesulfurization pathway. We will also analyze the substrate and product by high‐performance liquid chromatography to determine substrate specificity. These initial studies will provide a greater understanding towards the biodesulfurization mechanism for industrial purposes and pollution control.Support or Funding InformationThis research was supported by the Research Corporation (CCSA 22672) and by the National Institutes of Health (NIH) Grant 5SC2AI109500.This abstract is from the Experimental Biology 2018 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.

Investigating Amino Acid Residues in The Active Site of Dibenzothiophene Monooxygenase (DszC)

Fossil fuel combustion releases sulfur dioxide into the atmosphere, which is a harmful air pollutant and precursor of sulfate aerosols that contribute to acid rain. It is necessary to reduce atmospheric sulfur levels to mitigate these effects. A current method, hydrodesulfurization, is costly and inefficient at removing sulfur from complex aromatic compounds. Biodesulfurization is a cost‐effective alternative that utilizes bacteria to remove sulfur. Rhodococcus erythropolis uses a four enzyme pathway to remove sulfur from dibenzothiophene. The first enzyme of the pathway, dibenzothiophene monooxygenase (DszC), requires molecular oxygen, reduced flavin, and the formation of an intermediate, C4a‐hydroperoxyflavin, to sequentially oxidize dibenzothiophene to dibenzothiophene sulfone. This study aims to elucidate the roles of DszC active site residues in catalysis and binding and to enable rational engineering of DszC for future application in fuel refinement. Active site residue mutants were created using polymerase chain reaction, followed by plasmid DNA isolation and sequence confirmation. Steady state activity assays of DszC, quantitated by reverse‐phase HPLC, compared the amount of product formed by the mutants relative to wild type‐DszC. The ability of the mutants to form the intermediate was studied using stopped‐flow spectrophotometry. In this study, seven active site residue mutants were created and the percent of product formation by each mutant relative to wild type‐DszC was: His92Asn (12%), His92Gln (20%), Tyr96Phe (12%), His388Ala (38%), His388Asn (39%), His391Val (0%) and Asp392Ala (3%). These results indicate that all of the residues analyzed are necessary for proper product formation. Additionally, the intermediate formation rate constant for Tyr96Phe (1.03 × 104 M−1 s−1) was similar to wild type‐DszC (1.69 × 104 M−1 s−1). These results indicate that Tyr96 is not critical for proper intermediate formation, but has another role in catalysis as evidenced by the low (12%) product formation. His92Asn and Asp392Ala were also analyzed using stopped‐flow spectrophotometry but showed no intermediate formation signifying that these residues are essential to proper intermediate formation. Overall, these results show the necessity of all the residues presented in product formation and the fundamental roles of residues His92 and Asp392 in intermediate formation.Support or Funding InformationNational Institute of Health (NIH SCORE 5SC2AI109500)Research Corporation (CCSA 22672)MBRS/RISE Program/National Institute of Health (Grant 2R25GM063787‐10)This abstract is from the Experimental Biology 2018 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.

Structural and Biochemical Characterization of BdsA from Bacillus subtilis WU-S2B, a Key Enzyme in the "4S" Desulfurization Pathway.

Dibenzothiophene (DBT) and their derivatives, accounting for the major part of the sulfur components in crude oil, make one of the most significant pollution sources. The DBT sulfone monooxygenase BdsA, one of the key enzymes in the “4S” desulfurization pathway, catalyzes the oxidation of DBT sulfone to 2′-hydroxybiphenyl 2-sulfonic acid (HBPSi). Here, we determined the crystal structure of BdsA from Bacillus subtilis WU-S2B, at the resolution of 2.2 Å, and the structure of the BdsA-FMN complex at 2.4 Å. BdsA and the BdsA-FMN complex exist as tetramers. DBT sulfone was placed into the active site by molecular docking. Seven residues (Phe12, His20, Phe56, Phe246, Val248, His316, and Val372) are found to be involved in the binding of DBT sulfone. The importance of these residues is supported by the study of the catalytic activity of the active site variants. Structural analysis and enzyme activity assay confirmed the importance of the right position and orientation of FMN and DBT sulfone, as well as the involvement of Ser139 as a nucleophile in catalysis. This work combined with our previous structure of DszC provides a systematic structural basis for the development of engineered desulfurization enzymes with higher efficiency and stability.

Os tumoral : O.35 – O.40

Biodesulfurization is an eco-friendly process for removing sulfur from petroleum fractions. The process could not be commercialized because of the inability of microorganisms to desulfurize a wide range of heterocyclic poly aromatic sulfur compounds like dibenzothiophene (DBT), 4, 6-Dimethyl DBT present in fuel and low desulfurization activity. In the present study, to improve the rates of conversion of dibenzothiophene to dibenzothiophene sulfone, the responsible enzyme dibenzothiophene monooxygenase DszC, is displayed on the surface of Escherichia coli. This helped in overcoming the mass transfer limitation and resulted in approximately 3 times faster conversion with respect to control (which contained intracellular enzyme). This is the first report demonstrating display of a biodesulfurization enzyme on bacterial cell surface.

Diesel HDS performance of alumina supported CoMoP catalysts modified by sulfone molecules produced by ODS process

Oxidative desulfurization reaction (ODS) of Straight Run Gas Oil (SRGO) was carried out on a CoMoP catalyst, classically used in hydrotreatment. Optimum Co/Mo ratio for the ODS reaction was found at 0.5, which also corresponds to an optimum ratio for HDS. This catalyst allowed to oxidize sulfur compounds to more polar sulfones which can be adsorbed on the catalyst and served as modifying agent. The catalyst before and after ODS and the CoMoP catalyst modified by a commercial dibenzothiophene sulfone (DBTO2) were tested in gas oil HDS and better performances were obtained for the modified catalysts for a sulfone content of 10wt%. This effect was attributed to the redispersion of cobalt species observed after modification, leading to more efficient promotion.

Ultra-deep desulfurization of diesel fuel via selective adsorption over modified activated carbon assisted by pre-oxidation

Commercial adsorbents were tested for removing the dibenzothiophene sulfone (DBTO) from a model diesel fuel and organosulfur oxidized products (sulfones) from a real diesel fuel under ambient conditions. Activated carbons treated by concentrated H2SO4 at high temperature showed increasing adsorption capacity and affinity towards DBTO. On the basis of adsorption tests and the characterization by BET, base titration, SEM, XPS, Visible-Raman and FTIR, the acidic-oxygenated groups incorporated to the surface act as adsorption sites for selective adsorption of sulfone. The specific interaction may be formed through the acid-base interaction involving the SO group. Activated carbon treated by steam at 900 °C and followed by concentrated H2SO4 at 250 °C displayed significantly enhanced DBTO adsorption performance and a sulfur capacity of 5.8 mg S/g adsorbent for removing organosulfur compound from a real diesel to less than 10 ppmw.

Adsorptive removal of dibenzothiophene sulfone from fuel oil using clay material adsorbents

Dibenzothiophene sulfone (DBTO) adsorption utilizing clay material adsorbents such as activated clay, bentonite and kaolinite were investigated in this study. The properties of each adsorbent were characterized using Fourier transform infrared spectroscopy, scanning electron microscope, Brunauer, Emmett and Teller surface area analyzer and zeta potential. The effects of pH (1.0–5.0), contact time (5 min–48 h), temperature (298–328 K) and initial concentration (10–1000 mg/L) were examined in a batch adsorption process to determine the suitability of clay material adsorbents in DBTO removal. Kinetic models of pseudo-first order, pseudo-second order and intraparticle diffusion were used to assess the experimental data. Results showed high correlation to the pseudo-second order kinetic model (R2 > 0.99) that implies chemisorption as the rate-limiting step. Isotherm models of Langmuir, Freundlich, Temkin and Dubnin-Radushkevich were used to evaluate the equilibrium experimental data. DBTO adsorption showed a good fit towards the Freundlich isotherm (R2 > 0.99) which indicates a heterogeneous adsorption onto the adsorbent. Thermodynamic studies indicated that DBTO adsorption onto clay material adsorbents was endothermic. Utilizing the adsorbent of activated clay was spontaneous while kaolinite was non-spontaneous at 298–328 K. Bentonite was found to be only non-spontaneous at 298 K. Activated clay displayed a good potential in adsorbing sulfones to achieve low sulfur fuel oil in an oxidative desulfurization process.

Preparation and Characterization of Mg/TiO2 for Visible Light Photooxidative-Extractive Deep Desulfurization

A series of Mg/TiO2 photocatalysts were prepared using aqueous wet impregnation method at different Mg loading followed by calcination at different temperatures for 1 h duration. The photocatalysts were characterized using thermal gravimetry, Fourier-transform infrared spectroscopy, x-ray diffraction, field emission scanning electron microscopy and high-resolution transmission electron microscopy. The photocatalysts were investigated for photooxidative-extractive deep desulfurization of model oil containing dibenzothiophene at room temperature and under visible light irradiation. The model oil containing 100 ppm S was photooxidized followed by extraction using imidazolium-phosphate ionic liquids at room temperature. The best performing photocatalyst was 0.25 wt. % Mg/TiO2 calcined at 400°C (0.25Mg400), in which 98.4% of dibenzothiophene (3.070 mmol DBT per g photocatalyst) was converted to dibenzothiophene sulfone. The highest extraction efficiency of 97.8% (0.01525 mmol S per mL ionic liquid) was displayed by 1,2-diethylimidazolium diethylphosphate.

Crystal structure of dibenzothiophene sulfone monooxygenase BdsA from Bacillus subtilis WU-S2B.

The dibenzothiophene (DBT) sulfone monooxygenase BdsA from Bacillus subtilis WU-S2B catalyzes the conversion of DBT sulfone to 2'-hydroxybiphenyl 2-sulfinate. We report the crystal structures of BdsA at a resolution of 2.80 Å. BdsA exists as a homotetramer with a dimer-of-dimers configuration in the crystal, and the interaction between E288 and R296 in BdsA is important for tetramer formation. A structural comparison with homologous proteins shows that the orientation and location of the α9-α12 helices in BdsA are closer to those of the closed form than those of the open form in the EDTA monooxygenase EmoA. Proteins 2017; 85:1171-1177. © 2017 Wiley Periodicals, Inc.

Adsorptive Removal of Dibenzothiophene and Dibenzothiophene Sulfone over Mesoporous Materials

Dibenzothiophene (DBT, a typical sulfur compound) and dibenzothiophene sulfone (DBTO2, an oxidation product of DBT) were chosen as the model compounds, and their adsorption over a mesoporous silica (MCM-41) and a mesoporous carbon (CMK-3) were conducted under the exact same conditions. The adsorption amounts of DBTO2 over both adsorbents were enhanced compared to the DBT adsorption amounts, which clearly demonstrated that a combination of oxidation and adsorption is better than direct adsorption to achieve a better desulfurization performance. Besides, it was found that CMK-3 performed better for DBT removal compared to MCM-41, but the adsorption amount of DBTO2 over MCM-41 exceeded the corresponding value over CMK-3 (1.60 vs 0.88 mgS/g in p-xylene). Moreover, model fuels with varied hydrocarbon compositions were employed to investigate the impact of arene amounts. Finally, jet and diesel fuels were oxidized and treated with MCM-41, resulting in 85.6% and 81.4% sulfur removal, respectively. In contrast, w...

PET-modified red mud as catalysts for oxidative desulfurization reactions

This work describes the synthesis of catalysts based on red mud/polyethylene terephthalate (PET) composites and their subsequent heat treatment under N2 atmosphere. The materials were characterized by scanning electron microscopy (SEM), temperature programmed reduction (TPR), Fourier transform infrared spectroscopy (FT–IR), X-ray diffraction (XRD), thermogravimetric (TG) analysis and N2 adsorption/desorption. The catalysts were evaluated in the oxidative desulfurization reaction of dibenzothiophene (DBT) in a biphasic system. The results indicated that the PET impregnation on red mud increased the affinity of the catalyst with the nonpolar phase (fuel), in which the contaminant was dissolved, allowing a higher conversion (up to 80%) and selectivity to the corresponding dibenzothiophene sulfone. The sulfone compound is more polar than DBT and diffused into the polar solvent as indicated by the data obtained via gas chromatography–mass spectrometry (GC–MS).

Removal of sulfone compounds formed in oxidative desulfurization of middle distillate

How to remove the sulfone species formed in oxidative desulfurization (ODS) of middle distillates through an efficient method is crucial in a successful ODS process. In this study, the solubility of dibenzothiophene (DBT) sulfone in different hydrocarbon streams was assessed and investigated in detail, and the adsorptive removal of DBT-sulfone dissolved in a model hydrocarbon stream on activated carbon was also conducted. It was found that the saturation concentration of DBT-sulfone in the hydrocarbon streams is very low; being 0.0239wt.% in a toluene/hexadecane (20/80) mixture and 0.0181wt.% in a deep-hydrotreated middle distillate. The dissolved DBT-sulfone in the hydrocarbon stream can be removed easily by selective adsorption over an activated carbon adsorbent. On the basis of these findings, a two-step process for removing the sulfone species from the oxidation-treated middle distillate was proposed, which includes the first step of the centrifugal separation to remove the majority of the sulfone species (>80%) from the oxidation-treated middle distillate, followed by the second step of the selective adsorption to remove the remaining sulfone species. This two-step process may be more cost-efficient and environment-friendly to remove the sulfone species in the ODS process.

Dibenzothiophene Sulfone-Based Phosphine Oxide Electron Transporters with Unique Asymmetry for High-Efficiency Blue Thermally Activated Delayed Fluorescence Diodes.

Three asymmetrical electron transporters as dibenzothiophene sulfone (DBSO)-diphenylphosphine oxide (DPPO) hybrids, collectively named mnDBSODPO, were designed and prepared. All of these materials achieve the high triplet energy of ∼3.0 eV to restrain the exciton linkage from emissive layers. The dependence of inductive and steric effects for DPPO groups on the substitution position, the intermolecular interaction suppression, the encapsulations of high-polar DBSO cores, and the favorable electrical performance are successfully integrated on 36DBSODPO, which can simultaneously suppress the exciton quenching by formation of an interfacial dipole and enhancing the charge flux balance. As a result, 36DBSODPO endowed its tetralayer blue thermally activated delayed fluorescence (TADF) devices with impressive performance, including the maximum external quantum efficiency around 19%, and reduced efficiency roll-offs, which verifies the great potential of asymmetrical electron transporting materials for highly efficient TADF devices.

Oxidative desulfurization of fuels promoted by choline chloride-based deep eutectic solvents

In this study, a new type of “green solvents” named deep eutectic solvents (DESs) has been synthesized by combining hydrogen bond acceptors (HBAs) and hydrogen bond donors (HBDs). Choline chloride (ChCl) was chosen as typical HBA, and polyethylene glycol (PEG), 1,3-butyleneglycol (BG), ethylene glycol (EG), glycerol (Gl), propionate (Pr), malonic acid (MA) and urea (U) were chosen as HBDs. The extraction and catalytic oxidative desulfurization (ECODS) system was evaluated with phosphotungstic acid (HPW) as catalyst and 30wt% H2O2 as oxidant. Among all the neutral, acid and basic DESs, choline chloride/2polyethylene glycol (ChCl/2PEG) showed the best performance and 99.1% of dibenzothiophene (DBT) could be eliminated from model oil at 50°C within 3h. Interestingly, the volume ratio of DES to model oil was just 1:10, which was much less than the amount of extractant in the literature. The gas chromatography–mass spectrometer (GC–MS) analysis demonstrated that DBT sulfoxide (DBTO) and sulfone (DBTO2) were the products of oxidation of DBT. The desulfurization efficiency of the five sulfides in ECODS system occured in the following order: DBT>4-MDBT>4,6-DMDBT>3-MBT>BT.