Extractive Desulfurization Research Articles

Quaternary Ammonium Salts-Based Deep Eutectic Solvents: Utilization in Extractive Desulfurization

Quaternary Ammonium Salts-Based Deep Eutectic Solvents: Utilization in Extractive Desulfurization

Oxidative Extractive Desulfurization System for Fuel Oil Using Acidic Eutectic-Based Ionic Liquid

The biggest challenge faced in oil refineries is the removal of sulfur compounds in fuel oil. The sulfur compounds which are found in fuel oil such as gasoline and diesel, react with oxygen in the atmosphere to produce sulfur oxide (SOx) gases when combusted. These sulfur compounds produced from the reaction with oxygen in the atmosphere may result in various health problems and environmental effects. Hydrodesulfurization (HDS) is the conventional process used to remove sulfur compounds from fuel oil. However, the high operating conditions required for this process and its inefficiency in removing the organosulfur compounds turn to be the major drawbacks of this system. Researchers have also studied several alternatives to remove sulfur from fuel oil. The use of ionic liquids (ILs) has also drawn the interest of researchers to incorporate them in the desulfurization process. The environmental effects resulting from the use of these ILs can be eliminated using eutectic-based ionic liquids (EILs), which are known as greener solvents. In this research, a combination of extractive desulfurization (EDS) and oxidative desulfurization (ODS) using a photocatalyst and EIL was studied. The photocatalyst used is a pre-reported catalyst, Cu-Fe/TiO2 and the EIL were synthesized by mixing choline chloride (ChCl) with organic acids. The acids used for the EILs were propionic acid (PA) and p-toluenesulfonic acid (TSA). The EILs synthesized were characterized using thermogravimetry analyser (TGA) differential scanning calorimetry (DSC) analysis to determine the physical properties of the EILs. Based on the TGA analysis, ChCl (1): PA (3) obtained the highest thermal stability whereas, as for the DSC analysis, all synthesized EILs have a lower melting point than its pure component. Further evaluation on the best EIL for the desulfurization process was carried out in a photo-reactor under UV light in the presence of Cu-Fe/TiO2 photocatalyst and hydrogen peroxide (H2O2). Once the oxidation and extraction process were completed, the oil phase of the mixture was analyzed using high performance liquid chromatography (HPLC) to measure the sulfur removal efficiency. In terms of the desulfurization efficiency, the EIL of ChCl (1): TSA (2) showed a removal efficiency of about 99.07%.

Toward solvent screening in the extractive desulfurization using ionic liquids: QSPR modeling and experimental validations

In the present study, the effects of different structures of the involved compounds (such as cation, anion, and hydrocarbon) in the ternary systems on the distribution coefficient of the thiophene between ionic liquid and hydrocarbon-rich phases have been studied using Quantitative Structure-Property Relationship (QSPR). By a comprehensive literature survey, the experimental data of the distribution of thiophene for 84 different ternary systems with 763 data points have been collected. The data set includes 14, 10, and 10 different cation, anion, and hydrocarbon structures, respectively. A general QSPR model has been developed to evaluate the simultaneous effect of the hydrocarbon structure, the cation structure, and the anion structure on the thiophene distribution between the hydrocarbon and ionic liquid-rich phases. The selected molecular descriptor in this model was simple descriptor of the number of carbon atom (nC) for the cation structure, the number of nitrogen atom (nN) for the anion structure, and “Pol” for the hydrocarbon structure. The outcome of the internal validation, the external validation, and the statistical evaluation of the final QSPR models (R2 = 0.91, %AARD = 17.28) confirmed the acceptable prediction capability. The Liquid-Liquid Equilibrium (LLE) data has also been generated using the QSPR approach for a vast number of non-studied ternary systems for the first time. The LLE data of four different ternary systems ([C2MIM][EtSO4] (1) - Thiophene (2) - Cyclohexane, Methyl cyclohexane, n-Nonane, n-Decane (3)) was measured experimentally. The comparison of the measured experimental data and the predicted data using the developed QSPR model confirmed the validity of the QSPR developed model, again.

Extractive desulfurization of diesel fuel by amide-based type IV deep eutectic solvents

As promising green alternative solvents for ionic liquids, deep eutectic solvents (DESs) have been widely used in separation, catalysis, synthesis, etc. Most of the researches have focused on the application of DESs formed by hydrogen bonding interaction. In this paper, amide-based type IV DESs were synthesized from metal chloride and amides with coordination interaction, and they were used for extractive desulfurization of fuels. The experimental results showed the DES ZnCl2/N-methylformanilide (ZnCl2/MFA) had the highest desulfurization efficiency with the Nernst partition coefficient (KN) as 2.41. The extraction mechanism was firstly explored by Fourier transform infrared spectrometer (FT-IR) and 1H nuclear magnetic resonance (1H NMR). Then density functional theory (DFT) study suggested that π-π interactions and CH···π interactions contribute mainly to effective removal of DBT from fuel oil by DESs.

EXTRACTIVE DESULFURIZATION OF FUEL OIL USING GLYCOL-BASED DEEP EUTECTIC SOLVENT MEDIATED BY HYDROGEN PEROXIDE AND GRAPHENE OXIDE

Sulfur-containing compounds in fuel oil is one of the major pollutants that contributes to air pollution. To solve this issue, separation of sulfurs is crucial to produce ultra-clean fuel oil according to Euro V standard. Conventional method uses hydrodesulfurization to separate sulfur, however the system requires harsh conditions to operate in a separation unit. Morever, it is inefficient to remove sterically hindered sulfur compounds such as dibenzothiophene, benzothiophene and 4, 6-dimethyldibenzothiophene. An alternative to the current technology is using integrated extractive and catalytic-oxidative desulfurization. Many researchers has attempted to use ionic liquid as the extractant, however due to its complexity of synthesis and expensive starting material, the analogue of ionic liquid which is deep eutectic solvent (DES) could be a promising candidate to desulfurize fuel oil. In this work, four types of glycol-based DES (glycerol, ethylene glycol, tetraethylene glycol and poly(ethylene glycol) 400 (PEG)) with tetrabutylammonium chloride (TBAC) as salt have been synthesized in different mole ratios to study the effect of glycols towards desulfurization efficiency. Higher desulfurization can be achieved when using DES compared to glycol itself as solvent due to the synergistic effect of salt and glycols. The performance of desulfurization can reach as high as 66.24% when using TBAC:PEG in 1:2 mole ratio in ambient condition in the presence of hydrogen peroxide as oxidant and graphene oxide as catalyst. The hydrogen peroxide helps to oxidize dibenzothiphene into high polar dibenzothiophene sulfone so that it be easily extracted into the layer of DES and the process is mediated by the graphene oxide. The main reason for the enhanced performance is longer repeating ethoxy chains of polyethylene glycol which favoured the oxidized sulfur species to be extracted.
 Keywords: sulfur, desulfurization, deep-eutectic solvent, glycol, graphene oxide, oxidation

Extraction desulphurization of fuels using ZIF-8-based porous liquid

Porous ionic liquids (PILs), coupling the permanent porosity of porous solids with the good solubility and liquid fluidity of ionic liquids, have been successfully synthesized and offer great opportunities in the development of adsorption and separation. In this study, series of zeolitic imidazolate framework-8 based PILs (ZIF-8-PILs) are constructed and used for extractive desulfurization of fuels. Effects of extraction time, temperature, mass ratio of PILs to model oil and initial sulfur concentration on desulfurization are investigated. ZIF-8-based N-butylpyridinium bis(trifluoromethanesulfonyl)imide PILs (ZIF-8/[Bpy][NTf2]) exhibits encouragingly high performance with the removal efficiencies of thiophene (TH) and benzothiophene (BT) of 72.41% and 80.87% under optimum extraction conditions. After extraction, PILs can be facilely recovered and reused with steady removal efficiencies. The stable liquid porous structure of ZIF-8-PILs plays a dominant role for the excellent extractive desulfurization performance, and the synergistic effects of electrostatic interaction, hydrogen bonding and π-complexation interaction among ILs, ZIF-8 and sulfur compounds are also closely relevant to the high removal efficiency. The results of this work show that PILs are a new and promising extractant for fuel extraction desulfurization process.

Methane sulfonic acid ionic liquid extraction of gasoline desulfurization process and enhancement of microchannel technology

Methane sulfonic acid (MSA) was used as anion to synthesize a series of ionic liquids and its desulfurization performance was evaluated by extraction. The basic physical properties and structural properties of the ionic liquids were evaluated, and it was proved that the ionic liquids could be used and separated well in liquid–liquid extraction desulfurization (EDS) system. The liquid–liquid extraction desulfurization system was enhanced by microchannel technology. The effects of microchannel diameter, extraction temperature, residence time and extraction stage on extraction efficiency were discussed. In the microchannel extraction system, this extraction equilibrium time can be reduced to 60 s from more than 10–15 min or longer in the conventional intermittent extraction techniques, which effectively reduces the synthesis and production cost. This finding may provide some reference for the further study of the micro-reaction technology in the deep removal of sulfur compounds from gasoline by ionic liquid, and further optimize the operating conditions.

Fundamental research on the influence of mercaptan and thioether structure on the solvent extraction of fluid catalytic cracking naphtha

The thioether and mercaptan components (over 50–100 mg/kg) of fluid catalytic cracking (FCC) naphtha must be removed to satisfy the rigorous sulfur content standard of the vehicle gasoline. Owing to the difference between the structures of thioether and mercaptan and that of thiophenic sulfur, the desulfurization process is usually divided. A serious loss of octane number (ON) occurs during typical desulfurization when the sulfur content is reduced to 10 mg/kg. With the oriented separation of FCC naphtha critical components process, the standard of sulfur content with losing 1 unit of ON can be satisfied. However, thioether and mercaptan require individual technologies for removal. Thioether, mercaptan, and thiophenic sulfur must be synchronously removed to improve the efficiency, simplify the technology, and reduce the energy consumption. In this study, quantum chemical calculation and ternary liquid–liquid equilibrium experiment were combined to investigate the effect of thioether and mercaptan structures on the sulfoxide solvent extraction performance. The results showed that the Van der Waals’ force was the main interaction between the thioether/mercaptan and the solvent because the peaks of solvent and sulfide by RDG analysis were located at −0.01 to 0.01 a.u. In addition, the dipole moment, steric hindrance, and displacement affected the solvent extraction performance. The selectivity coefficient θ¯ of C3 thioether and mercaptan was 5.80 and 6.48 by DMSO solvent, respectively, which were greater than those of C4 sulfides (4.48 and 5.56). The interaction energy Eint of DMSO-ethyl methyl sulfide and DMSO- propanethiol were −32.75 and −33.68 kJ/mol while DMSO-diethyl sulfide and DMSO- butanethiol were −24.72 and −29.20 kJ/mol. It also proves that the C3 thioether and mercaptan could better extract into the solvent. In this way, the extractive desulfurization rate of the real FCC naphtha by DMSO was 80%. Therefore, the use of sulfoxide composite solvent can simultaneously extract the thioether, mercaptan, and thiophenic sulfur. This analytical method could be used to predict the synchronous extraction performance for FCC naphtha sulfides by other typical solvents.

Extractive desulfurization of dibenzothiophene from normal octane using deep eutectic solvents as extracting agent

Among the most important causes of air pollution we may refer to hydrocarbon fuels with a large content of organosulfur compounds. These compounds must be removed to the level of standard concentration for which different techniques are commonly in use. Since, desulfurization of aromatic sulfur compounds, such as thiophenes, is not possible by common methods such as hydrodesulfurization, other methods should be considered. In recent years, scientists have focused on extractive desulfurization using Deep Eutectic Solvents (DES) as a new method for removing organosulfurs from hydrocarbon fuels. In this research, two new DESs are synthesized. As the model fuel, we used n-octane, and dibenzothiophene (DBT) was chosen as the organosulfur content with a 1000 ppm concentration. DESs were synthesized by mixing quaternary ammonium salts and trifluoroacetic acid in a heating method. The structures of DESs were confirmed by FTIR and H-NMR analyses. The extraction process was first carried out at temperatures ranging from 25 to 40 °C. The results showed that the best temperature was 35 °C. Then, the effect of fuel to DES mass ratio (i.e. different compositions of feed), on extraction efficiency was examined. For thermodynamic modeling of liquid–liquid equilibrium the Non Random Two Liquid (NRTL) activity coefficient model was implemented. The parameters of the NRTL model were correlated using the binary data obtained from solubility experiments. Finally, the adjusted parameters were used for predicting ternary phase equilibrium data obtained in this work. The root mean square deviation from experimental data was less than 0.11% for each solvent.

Oxidative and extractive desulfurization of petroleum middle distillates, using imidazole ionic liquids

The desulfurization of four petroleum distillates i.e. kerosene, light gas oil (LGO), heavy gas oil (HGO) and light cycle oil (LCO), with sulfur content 0.206–1.272% w/w, was carried out using the hydrogen peroxide-acetic acid oxidative system, in combination with extractive desulfurization performed by imidazolium based ionic liquids. The 1-butyl-3-methylimidazolium bromide [BMIM][Br], and 1-butyl-3-methylimidazolium hydrogen sulfate [BMIM][HSO4] were synthesized, characterized with FT-IR and 1H NMR, and used as solvents in a six extraction cycle procedure. The influence of temperature in the extraction process was investigated. In each extraction cycle, the sulfur content and the physical properties of the raffinates were estimated. The used ionic liquids were recovered and regenerated, in a quite efficient regeneration process. The synthesized and recycled ionic liquids show a mild desulfurization capability, depending on the feed under extraction. In every case, [BMIM][Br] prevails over [BMIM][HSO4] in desulfurization efficiency.

A study on thiophene removals from model oils with different molecular compositions using an inexpensive N-methylpyrrolidone-FeCl3 ionic liquid

Extraction desulfurization technology (EDS) has been widely concerned because of its mild process conditions and low loss of octane number. At present, most of researches on EDS reported in literature mainly adopt single chain alkane as model oil. However, the chemical composition of fluid catalytic crack (FCC) gasoline is quite different from that of single chain alkane. Therefore, in this paper, the removal of thiophene from model oils containing different molecular compositions, such as n-octane, cyclohexane, 1-octene, cyclohexene and toluene, was systematically studied, using NMP + nFeCl3 (n = 0, 5 wt%, 10 wt%, 20 wt%) as extractants. The effects of different molecular compositions on desulfurization rate and the selectivity of extractants were systematically investigated, and their interaction mechanisms were discussed. The experimental results showed that the effects of different molecular compositions on desulfurization rate and selectivity were quite different, with the order of toluene > cyclohexene >1-octene > cyclohexane > n-octane. The higher the π electron cloud densities of the investigated molecular compositions or the more similar their chemical structures to extractants, the lower the desulfurization rates and selectivities. Moreover, the CH⋯π interaction between the investigated molecular composition and the extractant had a greater influence on desulfurization rate and selectivity than ring structure. The desulfurization results of simulated FCC gasoline showed that the selectivity and desulfurization rate of simulated gasoline containing olefins and aromatics were far lower than those of n-octane reported in the literature. The desulfurization results of real gasoline showed that the desulfurization rate and selectivity of real gasoline were also significantly lower than those of n-octane model oil.

Combined extractive and oxidative desulfurization approach based on ultrasound and ultraviolet irradiation with additives for obtaining clean fuel

Abstract The combined extractive and oxidative desulfurization approach based on ultrasound (US) and ultraviolet (UV) irradiations with additives was investigated for treatment of simulated fuel comprising of thiophene as model sulfur component and toluene as representative fuel with an objective of obtaining a clean fuel. Experiments were performed at constant conditions of ultraviolet light and/or ultrasound with varied operating parameters as initial thiophene concentration (over the range 100–800 ppm), temperature (40 °C–80 °C), catalyst loading (0.25 to 1.5 g/L), and oxidant loading (5 mL/L to 15 mL/L) followed by the step of extraction under fixed conditions to establish the effect on desulfurization. Complete thiophene removal was achieved at best operating conditions of 1 g/L as catalyst loading, 12.5 mL/L as oxidant loading, 60 °C as temperature and 200 ppm as the initial concentration of thiophene within 50 min of treatment. The extent of desulfurization was significantly higher for the combination approach than achieved for individual approach of ultrasound and UV irradiation. The activation energy was found to be 25.86 kJ/mol. The gasoline desulfurization followed pseudo first order kinetics whereas the thermodynamic analysis demonstrated same spontaneity at varied temperature. The values of Delta G and Delta H were found to be 92.88 kJ/mol and 23.09 kJ/mol, respectively. The cavitational yield was significantly higher (8.82 × 10−8 mg/J) for the combination approach. Overall, it was clearly demonstrated that the combined US/UV approach coupled with use of oxidants and catalyst at optimum conditions was the best treatment approach leading to effective removal of thiophene from the model fuel considered in the work.

Synthesis of t‐B.PWFe/NiO nanocomposite as an efficient and heterogeneous green nanocatalyst for catalytic oxidative‐extractive desulfurization of gasoline

AbstractThis study aimed to improve the efficiency of sulfur removal from real and model liquid fuel, which is still a challenge. The heterogeneous nanocatalyst was synthesized successfully by supporting ([n‐C4H9]4N)4H[PW11FeO39] (t‐B.PWFe), on nickel oxide (NiO) as a new nanocomposite (t‐B.PWFe/NiO) via sol–gel method. The catalytic activity of the nanocomposite was evaluated for oxidative–extractive desulfurization (OEDS) of model fuel and real gasoline using CH3COOH/H2O2 as an oxidant. The synthesized nanocatalyst was characterized by means of X‐ray diffraction, scanning electron microscopy, Fourier transform infrared, ultraviolet–visible spectroscopy (UV–Vis), and cyclic voltammetry. From UV–Vis, the bandgap energy is found. After OEDS treatments, the obtained results were specified that mercaptans and total sulfur content of real gasoline lowered with about 97% yield. Mechanisms, kinetic studies, and the effect of various operational parameters were evaluated, such as temperature and time on the oxidation reaction. The unique performance of the t‐B.PWFe/NiO proved the extreme capability of this system for sulfur removal to achieve purified and clean gasoline.

A Hierarchical Hybrid Method for Screening Ionic Liquid Solvents for Extractions Exemplified by the Extractive Desulfurization Process

A hierarchical hybrid method combining experimental-database-derived estimation of extraction performance, quantitative structure–property relationship (QSPR)-based assessment of IL physical and environmental properties, liquid–liquid extraction (LLE) measurement, and process evaluation is proposed to screen practically suitable ionic liquid (IL) solvents for different extractions. From the literature, 47 424 infinite dilution activity coefficient (IDAC) data including 12 IL families (e.g., imidazolium, pyridinium, ammonium, etc.) and 13 organic families (e.g., alkanes, aromatics, alcohols, etc.) are collected. On the basis of the IDAC data, the extraction performance of ILs for a specific separation can be estimated in terms of the distribution ratio and selectivity at infinite dilution. The ILs with potentially high extraction performance and meeting the physical and environmental properties criteria are selected to perform LLE experiments. Subsequently, process simulation and evaluation using the selected IL solvents are performed by Aspen Plus. To exemplify the proposed method, the extractive desulfurization (EDS) process is taken as a case study, where [EMIM][MESO₃] (1-ethyl-3-methylimidazolium methanesulfonate) and [EIM][NO₃] (1-ethylimidazolium nitrate) are selected after IDAC database searching and QSPR analysis. Experimental LLE with the two ILs are determined, demonstrating their promising extraction performance with the maximum selectivity (S₂₃ᵐᵃˣ) for thiophene/heptane of 420 and 281.9, respectively. By fitting the NRTL model correspondingly, two processes using the screened ILs and sulfolane are developed and compared using Aspen Plus. It turns out that the two ILs save 66% and 48% in solvent requirements and 54% and 55% in energy consumption compared to those of sulfolane for the EDS task, respectively.

Triphenyl methyl phosphonium tosylate as an efficient phase transfer catalyst for ultrasound-assisted oxidative desulfurization of liquid fuel.

The novel phosphonium-based ionic liquid (IL), triphenyl methyl phosphonium tosylate ([TPMP][Tos]), has been synthesized and applied as a phase transfer catalyst (PTC) in the ultrasound-assisted oxidative desulfurization (UAODS). Oxidation of model fuel (MF) containing dibenzothiophene (DBT) was carried out using an equimolar mixture of H2O2-CH3COOH as an oxidant at 40-70 °C in the presence of IL. The sulfur compound is converted into polar sulfone, and the maximum desulfurization efficiency was examined. The effect of process parameters such as reaction temperature, reaction time, molar ratio of oxidant to sulfur (n(O/S)), and the mass ratio of ionic liquid to model fuel (m(IL/MF)) was studied, and the conditions for maximizing the DBT conversion rate were found. Maximum conversion (> 99%) was obtained at a temperature of 70 °C with m(IL/MF) of 0.8. The oxidation reactivity of various sulfur compounds was studied at different time intervals. To verify the effect of ionic liquid and ultrasound irradiation, extractive desulfurization (EDS), oxidative desulfurization (ODS), and UAODS in the presence of IL were carried out. The experimental results show that the UAODS process gives the highest desulfurization efficiency. A kinetic study was performed to estimate the rate constant and the order of oxidation reaction.

Insight into the mechanism of tuned extractive desulfurization by aqueous tetrabutylphosphonium bromide

Molecular dynamics simulations with the combination of FT-IR and 1H NMR spectra were carried out to study the mechanism of tuned extractive desulfurization by aqueous tetrabutylphosphonium bromide (TBPB). The intermolecular interaction and microstructure of TBPB with water and the sulfur compound dibenzothiophene (DBT) were investigated. Both the spectra and MD simulation results indicated that TBPB with a small amount of water has strong CH–π interaction between TBP+ cation and dibenzothiophene (DBT) and hydrogen bonding between Br− anion and DBT, which are the driving forces for extraction of DBT into aqueous TBPB phase in fuel desulfurization. Further addition of water into aqueous TBPB phase causes the solvation of cation and anion, which weakens the interactions of TBPB with DBT and hence facilitates DBT aggregation and TBPB recovery. The results provide an insight into the mechanism of water tuned extraction and regeneration process in fuel desulfurization.

Selection of ionic liquid for extraction processes: Special case study of extractive desulfurization

Selecting of appropriate ionic liquids (ILs) as extracting agents is a key to ensuring an extraction process. Therefore, this study illustrates a systematic method for an extractive desulfurization (EDS) process to select the most promising ILs. The proposed method combines: 1) COSMO-RS calculation of the mutual solubility of ILs and fuel oil, and the capacity of ILs for the S-compounds, 2) experimental investigation of the prescreened ILs for their desulfurization ability, 3) and Aspen Plus simulation of developing a new insight into the industrial application of EDS. Based on the obtained results, [C1pyr][H2PO4] and [C1pyr][HSO4] having small mutual solubility with fuel oil, high extraction capacity for S-compounds and high desulfurization efficiency are selected as two promising ILs. Considering the qualification of the low sulfur content standard and real industrial applications, [C1pyr][H2PO4] is recognized as the most favorable solvent for the EDS process. The proposed method initiating from micro-level to experimental stage and finally to industrial stage can preferably be extended over a variety of extraction application for selection of the promising ILs.

Size-matched polyoxometalate encapsulated in UiO-66(Zr): an extraordinary catalyst with double active sites for the highly efficient ultra-deep oxidative desulfurization of fuel oil

In this study, for the first time, we selected a size-matched polyoxometalate α-Mo8O26, and successfully prepared Mo8-UiO-66(Zr) as a catalyst with double active sites for extractive and catalytic oxidative desulfurization systems (ECODS).

Improving the extraction of sulfur-containing compounds from fuel using surfactant material in a digital baffle reactor

Abstract Extraction desulfurization process (EDP) for dibenzothiophene (DBT) from model light gas oil (LGO) improved using solvent mixture with new surfactant material (sodium thiosulfate) in digital baffle batch reactor (DBBR). Surfactant material was help increase extraction surface through increase dispersion of solvent in LGO. Reactor design was the best designer where negligible region of died zone in the reactor, rotation of fuel beside of wall, because adding the baffle on the wall. The blade design was distributes hexagonal holes that help liquid cross with solvent and this increases mixing and mass transfer DBT from model LGO to solvent. Operational conditions effects on extractive desulfurization process (EDP) it’s found such as solvent mixture (methanol, ethanol and toluene) to LGO model ratio, speed of impeller, extraction temperature, extraction time and effect surfactant were explored. Optimal experimental results represented that the extraction conditions were; (methanol = 10 ml, ethanol = 10 ml, toluene = 10 ml and volume of cocktail solvent equal to 30 ml MET))/model of LGO ratio speed of impeller 450 rpm, extraction time 21 min and extraction temperature 85 °C. Maximum DBT removal from model LGO was obtained at 89.8%, at this operating condition. Higher polarity of DBT was obtained when solvent used 30 ml MET. For removal dibenzothiophene (DBT) from model light gas oil, the results indicate that the extraction desulfurization process is suitable method to improve fuel quality.

Highly efficient Co(II) porphyrin catalysts for the extractive oxidative desulfurization of dibenzothiophene in fuel oils under mild conditions

Co(II) porphyrins have been utilized as efficient and selective catalysts for the extractive oxidative desulfurization reaction on the refractory dibenzothiophene (DBT) in [Formula: see text]-dodecane (model middle distillate fuel oil). The acetonitrile was taken as extracting polar solvent and H2O2 was used as oxidant. The reaction optimization was done with respect to DBT:catalyst molar ratio; DBT:H2O2 molar ratio; extracting solvent: CH3CN/[Formula: see text]-dodecane volume ratio; reaction temperature and time. Under the optimized conditions, a maximum of [Formula: see text]98% DBT removal was achieved by using the meso-tetrakis(4[Formula: see text] methoxyphenyl)porphyrinatocobalt(II) as catalyst under mild conditions at 50[Formula: see text]C.