Oxidative Desulfurization of Dibenzothiophene Catalyzed by VO(acac)2 in Ionic Liquids at Room Temperature

A simple extraction and catalytic oxidative desulfurization (ECODS) system composed of VO(acac)₂, 30% H₂O₂, and 1-butyl-3-methylimidazolium tetrafluoroborate ([Bmim]BF₄) has been found to be suitable for the deep removal of dibenzothiophene (DBT) in model oil at room temperature. The optimal conditions were as follows: [n(H₂O₂)/n(DBT)/n(catalyst) = 100:20:1], model oil = 5 mL, ionic liquid [IL] = 1 mL, T = 30°C, t = 2 hr. With the ECODS system, the sulfur removal of DBT could reach 99.6%, which was superior to that of the simple extraction with IL (15.6%) or oxidation without catalyst (17.1%). The IL could be recycled five times without a significant decrease in activity.     

Optimization of Oxidative Desulfurization of Dibenzothiophene Using a Coordinated Ionic Liquid as Catalytic Solvent

Abstract

Oxidative desulfurization (ODS) of dibenzothiophene (DBT) in n-octane with hydrogen peroxide/acetic acid using a quaternary ammonium coordinated ionic liquid (IL) (C₄H₉)₄NBr · 2C₆H₁₁NO as catalytic solvent has been studied. The ODS mechanism by coordinated ionic liquid [(C₄H₉)₄NBr · 2C₆H₁₁NO] was also carried out. The sulfur-containing compounds in model oil were extracted into ionic liquid phase and oxidized to their corresponding sulfones by H₂O₂. The effect factors for desulfurization of model oil were investigated in detail by means of monofactorial and orthogonal experiments (L₁₆(4)⁴). The results showed that the desulfurization efficiency of model oil could reach 98.6% under the optimal conditions of oxidation time, oxidation temperature, molar ratio of H₂O₂/sulfur (O/S), and volume ratio of model oil to coordinated ionic liquid were 30 min, 50°C, 16, and 1, respectively. The influences to the desulfurization efficiency of DBT decreased in the following order: volume ratio of model oil to coordinated ionic liquid (C₄H₉)₄NBr · 2C₆H₁₁NO (V_{model oil}/V_IL) > molar ratio of O/S > oxidation temperature > oxidation time, according to extreme analysis of the orthogonal test. The coordinated ionic liquid (C₄H₉)₄NBr · 2C₆H₁₁NO can be recycled 5 times without a significant decrease in desulfurization.     

Zinc-Substituted Polyoxometalate for Oxidative Desulfurization of Dibenzothiophene

Abstract

An oxidative desulfurization process for model compound has been studied using Na₁₂[WZn₃(H₂O)₂(ZnW₉O₃₄)₂] · 46H₂O as catalyst and 30 wt% aqueous hydrogen peroxide as the oxidizing agent. The effects of the reaction time, the reaction temperature, the amount of the oxidizing agent and the catalyst on the removal of dibenzothiophene (DBT) were investigated. The oxidated resultant was removed by extraction with polar solvent to reduce the sulfur level in the model compound. The maximum removal of DBT was up to 70%.     

The Deep Oxidative Desulfurization of Fuels Using Na2WO4.2H2O in Acidic Ionic Liquids

The catalytic oxidation desulfurization system is composed of Na₂WO₄.2H₂O, H₂O₂, acidic ionic liquid, and phase transfer catalyst has been found suitable for deep removal of organic sulfur in fuels. Under the optimal conditions, the desulfurization efficiency is virtually 100%. Moreover, this acidic ionic liquid can be recycled five times without obviously decrease in activity. Meanwhile, the mechanism of oxidation desulfurization was also elaborated.     

The Research of Ultra-deep Desulfurization in Diesel via Ultrasonic Irradiation Under the Catalytic System of H2O2-CH3COOH-FeSO4

Abstract

In recent years, many countries have drawn up strict laws regarding the sulfur-containing compounds of fossil fuels, especially the gasoline and diese. Ultra-deep desulfurization of fuel is a main component of fossil fuel development. The experiment imposes the photochemistry field on the catalytic oxidation system in order to broaden the newly desulfurization technology. The sulfur-containing compounds, such as dibenzothiophene (DBT) and its derivatives, in diesel fuel are oxidized to corresponding sulfones using H₂O₂-CH₃COOH-FeSO₄ oxidation systems via ultrasonic irradiation. Later, the oxidized sulfur compounds (sulfones) are extracted by a suitable polar solvent. The influences of the catalytic system, reaction time, and ultrasonic source (frequency, intensity) are tested on desulfurization efficiency. Experimental results show that the removal efficiency of the sulfur compound could amount to 97.5%, and the recovery of oil is above 92% under the catalytic system of H₂O₂-CH₃COOH-FeSO₄ by the assistance of ultrasound.     

Oxidative Desulfurization of Fuel Oil with Hydrogen Peroxide Catalyzed by Keggin-type Polyoxotungstate in a DC Magnetic Field

Abstract

The oxidation of sulfur-containing compounds was conducted in a DC magnetic field-assisted system, composed of model compound or diesel, 30 wt% hydrogen peroxide, and an iron mono-substituted Keggin-type heteropolytungstate [(C₄H₉)₄N]₄ [PW₁₁Fe(H₂O)O₃₉] catalyst. By combining oxidative desulfurization (ODS) in a magnetic field and acetonitrile extraction, when magnetic field intensity was at 17.3 mT, the removal efficiency of the model compound dibenzothiophene (DBT) in petroleum ether with 1,000 ppm S can reach 98% at 70°C within 30 min with O/S ratio = 3 and catalyst dosage 5%, with 2% increase over that without magnetic field assistance. Under the same reaction conditions, the sulfur level of diesel oil was reduced from 5,647 to 508 ppm. This shows that the DC magnetic field facilitates the oxidation of sulfur-bearing compounds, which allowed greater sulfur removal efficiency under milder reaction conditions.     

Synthesis of amphiphilic peroxophosphomolybdates for oxidative desulfurization of fuels in ionic liquids

Three amphiphilic peroxophosphomolybdates [C₄mim]₃PMo₄O₂₄, [C₈mim]₃PMo₄O₂₄ and [C₁₆mim]₃PMo₄O₂₄ were synthesized and characterized. These catalysts were used for extraction and catalytic oxidative desulfurization of fuel with H₂O₂ as an oxidant and ionic liquid [C₄mim]BF₄ as an extractant. It was found that [C₁₆mim]₃PMo₄O₂₄ showed the highest catalytic activity and the sulfur content could decrease to 7.5 ppm. In contrast, the desulfurization system shows very low performance without H₂O₂ or ionic liquid. The detailed reaction conditions were optimized including reaction time, temperature, the dosage of H₂O₂ and catalyst, and different sulfur compounds. After the reaction, the catalysts and the ionic liquid can be cycled 8 times with a little decrease in desulfurization efficiency.     

Oxidative Desulfurization of Fuel Catalyzed by Amphiphilic Peroxomolybdate

Abstract

The oxidation of sulfur-containing compounds (benzothiophene [BT], dibenzothiophene [DBT], and 4,6-dimethyldibenzothiophene [4,6-DMDBT]) was studied in an emulsion system composed of model oil, hydrogen peroxide, and an amphiphilic catalyst [C₇H₇C₁₂H₂₅(CH₃)₂N]₂Mo₂O₃(O₂)₄. The most suitable conditions were suggested: n (DBT): n (catalyst): n (H₂O₂) = 1:0.1:10, at 60°C for 2 hr. Under optimized experimental conditions, the removal of DBT, BT, and 4,6-DMDBT could reach 98.0, 94.0, and 62.7%, respectively. The oxidation product sulfones could be readily separated by extraction. The catalyst could be recycled five times without a significant decrease in catalytic activity.     

The Deep Oxidative Desulfurization of Fuels Catalyzed by Surfactant-type Octamolybdate in Acidic Ionic Liquids

Four surfactant-type octamolybdates were synthesized, characterized, and then used as effective catalysts associated with H₂O₂ as oxidant in the acidic ionic liquid, which has been found suitable for deep removal of organic sulfur in fuels. Under the favorable conditions, the sulfur removal could reach almost 100%, which was much better than desulfurization performance by the simple extraction with acidic ionic liquid. Moreover, this acidic ionic liquid can be recycled six times by distillation without obviously decrease in activity. Meanwhile, the mechanism of oxidation desulfurization was also elaborated.     

An Improved Desulfurization Process Based on H2O2/Formic Acid Oxidation and Liquid-Liquid Extraction 2. FCC Diesel Oil Feedstocks

Abstract

Semi-empirical molecular orbital theory and parametric model 3 methods were used to calculate the quantum chemistry properties of dibenzothiophene (DBT) and its corresponding sulfone compounds to investigate the essential theory of a formic acid/H₂O₂ oxidation desulfurization system. To study oxidation kinetics of the oxidation desulfurization reaction, DBT was also employed as a model compound to obtain the oxidation kinetic parameters. Desulfurization of fluid catalytic cracking (FCC) diesel was also performed in this process, and the sulfur content was reduced from 7,200 μg·g^?1 to 598 μg·g^?1 after being extracted by polyethylene glycol 200.     

Desulfurization of FCC Gasoline Over Mordenite Modified with Al2O3

Abstract

Mordenite modified with Al₂O₃ (Al₂O₃/mordenite) was synthesized and used for the desulfurization of FCC gasoline. The influences of operating parameters on the results were studied for the model solution composed of dibenzothiophene (DBT) and isooctane. Al₂O₃/mordenite exhibits higher sulfur capacity than other kinds of chemisorbents. The suitable composition of the chemisorbent is 30 wt% Al₂O₃ to 70 wt% mordenite. The optimal operating parameters are: temperature 160°C; velocity 3 h^?1 (WHSV). Under the stated conditions, desulfurization was carried out for the FCC gasoline with sulfur content of 220.4 μg/g. The chemisorbent can maintain the sulfur content under 50 μg/g for 40 h and has good regeneration ability after desorption using benzene.     

Desulfurization by Oxidation/Adsorption Scheme over Ti3(PW12O40)4 Catalyst

Abstract

Due to the future specifications for sulfur content in gasoline, a lot of research work has been done to develop alternative methods for desulfurization. This work presents the results for the desulfurization by oxidation/adsorption scheme over Ti₃(PW₁₂ O₄₀)₄ catalyst. The desulfurization experiment was performed with hydrogen peroxide (H₂ O₂) as the oxidant in the presence of Ti₃(PW₁₂ O₄₀)₄/SiO₂-Al₂ O₃ catalyst and adsorbent prepared by the sol-gel method, by using dibenzothiphene (DBT) in petroleum ether as the model compound. The efficiency of Ti₃(PW₁₂ O₄₀)₄/SiO₂-Al₂ O₃ catalyst and adsorbent prepared by the sol-gel method towards DBT adsorption from model compound was studied. The effects of titanium content of the adsorbent and the reaction conditions, such as the reaction temperature, the amounts of adsorbent and hydrogen peroxide (H₂ O₂), and the reaction time, etc., on the desulfurization efficiency and regeneration performance of the catalyst were investigated. It was found that the Ti₃(PW₁₂ O₄₀)₄/SiO₂?Al₂ O₃ catalyst presented higher maximum desulfurization conversion than SiO₂-Al₂ O₃ solids. In addition, it showed higher desulfurization conversion after regeneration with N,N-dimethylamide. Optimal reaction conditions were determined as: a reaction temperature of 70°C, a Ti (titanium)/H(hydrogen) molar ratio of 3, an adsorbent amount of 5 wt%, a H₂ O₂/S molar ratio of 3, and a reaction time of 2 hr. As a result, the total sulfur content in the petroleum ether solution of DBT could be decreased after oxidation/adsorption scheme from an initial value of 200 μg/g to a value of 2 μg/g, and the desulfurization conversion reached 99%, which is a remarkable result. Further, the said adsorbent also had quite good regenerability.     

The Extractive Desulfurization of Fuels Using Ionic Liquids Based on FeCl3

Abstract

Six Lewis acid ionic liquids were synthesized and employed as extractants for desulfurization of the model oil containing dibenzothiophene (DBT). Very promising ionic liquid was 1-butyl-3-methylimidazolium chloride-FeCl3 ([bmim]Cl/FeCl3), which performed best in the studied ionic liquids under the same operating conditions. It can remove DBT from model oil after continuous extraction for four steps, and the desulfurization efficiency can reach 97.9% under mild reaction conditions. Other sulfur-containing compounds were also investigated. The used ionic liquid could be regenerated six times without a significant decrease in activity.     

Amorphous TiO2-supported Keggin-type ionic liquid catalyst catalytic oxidation of dibenzothiophene in diesel

Supported ionic liquid(IL) catalysts [C_nmim]_3PMo_(12)O_(40)/Am TiO_2(amorphous TiO_2) were synthesized through a one-step method for extraction coupled catalytic oxidative desulfurization(ECODS) system. Characterizations such as FTIR, DRS,wide-angle XRD, N_2 adsorption–desorption and XPS were applied to analyze the morphology and Keggin structure of the catalysts. In ECODS with hydrogen peroxide as the oxidant, it was found that ILs with longer alkyl chains in the cationic moiety had a better effect on the removal of dibenzothiophene. The desulfurization could reach 100% under optimal conditions, and GC–MS analysis was employed to detect the oxidized product after the reaction. Factors affecting the desulfurization efficiencies were discussed, and a possible mechanism was proposed. In addition, cyclic experiments were also conducted to investigate the recyclability of the supported catalyst. The catalytic activity of [C_(16)mim]_3 PMo_(12)O_(40)/Am TiO_2 only dropped from 100% to 92.9% after ten cycles, demonstrating the good recycling performance of the catalyst and its potential industrial application.     

Vanadium-catalyzed extractive oxidesulfurization of commercial diesel in ionic liquid with combined oxidizing agents

A series of vanadium catalysts were synthesized and employed in pyridinium phosphate [HPy][H₂PO₄] with various oxidants for extractive catalytic oxidesulfurization (ECODS) of diesel. The VO(acac)₂ showed high catalytic activity with HNO₃/H₂SO₄ and ionic liquid via microwave radiations in the MECODS of diesel. The sulfur removal could reach 98.9% in 210?s at 500?W, which was superior to that of the simple ECODS (89.3%) under optimal conditions (V_diesel?=?20?mL, VIL/Vdiesel volume ratio?=?0.075, m(VO(acaca)₂)/m_diesel?=?0.5?wt%, V(HNO₃)/V(H₂SO₄)?=?1 and T?=?80?°C). The catalytic system could be regenerated six times without significant loss of activity.     

Role of Mn/Al2O3 catalyst in deep oxidative desulfurization of diesel

Abstract

In this work, a series of supported manganese catalyst has been synthesized and utilized in oxidative desulfurization to remove 4,6-dimethyldibenzothiophene (4,6-DMDBT), dibenzothiophene (DBT) and thiophene. The influences of catalyst parameters were investigated including manganese precursors, manganese loading and calcination temperature in details. The synthesized catalyst was characterized by scanning electron microscopy (SEM), N₂ adsorption/desorption and X-ray diffraction (XRD) techniques. 90.2% of 4,6-DMDBT, 98.5% of DBT and 95.5% of thiophene conversion were achieved under mild operational conditions using 3Mn(NO₃)₂/Al₂O₃ at 500?°C calcination temperature. A slight decrease in desulfurization activity was observed after Mn/Al₂O₃ catalyst being used in five cycles ODS.     

Oxidation Desulfurization of Thiophene Using Phase Transfer Catalyst/H2O2 Systems

Abstract

In our study, an effective phosphomolybdic acid/hexadecyltrimethyl-ammonium bromide catalyst for oxidative desulfurization of thiophene in a model compound was formed. The oxidation activities of thiophene for a series of heteropoly acids were estimated. The results show that the oxidation activity of thiophene increased with increasing oxidation time, oxidation temperature, and the volume of 30% H₂ O₂ oxidant. The optimal values are 150 min, 40°C, and 3 mL, and sulfur removal attained 96.3% when phosphotungstic acid/hexadecyltrimethylammonium bromide was used as a catalyst.     

Diesel desulfurization using a UV-photocatalytic process

In this paper, the use of ultraviolet irradiation using TiO₂ as a photocatalyst for diesel desulfurization was studied in a batch reactor. The effects of operational parameters such as operation time, the presence of oxidant, oxidant type, and irradiation power on the performance of the desulfurization process were investigated. The results revealed that total sulfur and thiol group removals from diesel samples were about 61.91% and 58.64%, respectively, at the power of 18 W of UV irradiation and 2 wt% H₂O₂ as an oxidizing agent using 40 min of irradiation as an optimum time required. It was also found that hydrogen peroxide is the most promising oxidant for the desulfurization of diesel fuel. By increasing the power of ultraviolet irradiation from 18 W to 30 W, total sulfur removal and thiol group conversion were increased to 90% and 88%, respectively. However, total sulfur removal and thiol group conversion at 30 W ultraviolet irradiation with 2 wt% TiO₂ and without using any oxidants were about zero and 14%, respectively.     

Desulfurization using an oxidation/catalysis/adsorption scheme over H3PW12O40/SiO2−Al2O3 1

A desulfurization experiment was performed with tert-butyl hydroperoxide (t-BuOOH) as the oxidant in the presence of H₃PW₁₂O₄₀/SiO₂₋Al₂O₃ as the catalyst prepared by the sol-gel method, by using dibenzothiphene (DBT) in petroleum ether as the model compound. This work presents the results for the desulfurization by an oxidation/catalysis/adsorption scheme. The effects of catalyst amounts, t-BuOOH amounts, reaction temperature, and reaction time on the desulfurization efficiency and regeneration performance of the catalyst were studied. It was found that the H₃PW₁₂O₄₀/SiO₂-Al₂O₃ catalyst presented a higher maximum desulfurization conversion than SiO₂-Al₂O₃ solids also prepared by the sol-gel method. In addition, the H₃PW₁₂O₄₀/SiO₂-Al₂O₃ catalyst showed a higher desulfurization conversion after regeneration with N,N-dimethylamide. It was also found that the oxidation agent t-BuOOH resulted in a higher desulfurization conversion than hydrogen peroxide (H₂O₂). The text was submitted by the authors in English.     

Deep Desulfurization of Light Oil Using the Imitating Silver Salt ILs Method

Abstract

Sulfides in oils are harmful in many ways, in particular, deterioration of the environment resulting from sulfur dioxide. A novel desulfurization process for light oil has been investigated. A mixture consisting of benzothiophene (BT), dibenzothiophene (DBT), and oil fractions (235°C–270°C) refined by acid–alkali treatment was employed for alkylation desulfurization tests in a nitrogen atmosphere. The results showed that at a reaction temperature of 30°C, ratio of bromoethane (CH₃CH₂Br) to sulfur of 30:1 (mol/mol), ratio of silver tetrafluoroborate (AgBF₄) to sulfur of 6:1 (mol/mol), and reaction time of 16 hr, the desulfurization yield could reach 76.3%.