Oxidative Desulfurization Efficiency Research Articles

Oxidative Desulfurization of Simulated Diesel Fuel by Synthesized Tin Oxide Nano-Catalysts Support on Reduced Graphene Oxide

The modified Hummers method was applied to prepare graphene oxide (GO) from the graphite powder. Tin oxide nanoparticles with different loading (10-20 wt.%) supported on reduced graphene oxide were synthesized to evaluate the oxidative desulfurization efficiency. The catalyst was synthesized by the incipient wetness impregnation (IWI) technique. Different analysis methods like FT-IR, XRD, FESEM, AFM, and Brunauer-Emmett-Teller (BET) were utilized to characterize graphene oxide and catalysts. The XRD analysis showed that the average crystal size of graphene oxide was 6.05 nm. In addition, the FESEM results showed high metal oxide dispersions on the rGO. The EDX analysis shows the weight ratio of Sn is close to its theoretical weight. The reduction of metal oxide and (GO) has occurred in one step at temperatures of 400 °C for 2 hours. The performance of the catalysts for dibenzothiophene (DBT) removal using H2O2 as an oxidizing agent was determined under a range of different operating conditions. The results showed that the maximum desulfurization was 71.68% in the best conditions (DBT concentration = 385 ppm, time = 90 min, temperature = 60 oC, catalyst dosage = 0.04g, and amount of oxidant = 0.375 ml).

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

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

Enhancing the oxidative desulfurization efficiency of cobalt-loaded-porous carbon catalyst via nitrogen doping on carbon support

Melamine (M)-incorporated bimetallic (Zn/Co)-azolate framework-6s (M( x )@BM6s) (with wide M-contents) composites were firstly synthesized via an in-situ method and used as a precursor to derive Co/N-enriched porous carbon (M( x )@BMC6s) via pyrolysis. Very small Co-nanoparticles (4–10 nm) uniformly distributed on highly porous carbon with much N-doping were obtained from M( x )@BM6s. The developed Co-based materials with high N-content were used as catalysts for heterogeneous oxidative desulfurization (ODS) of liquid model fuel, critical for the environment and the petroleum industry . M( x )@BMC6s (with various N-contents), especially the M( 10 )@BMC6 (obtained from M( 10 )@BM6 with 10% M), were more competitive in ODS than orther tested Co-based catalysts (without or with less N-sites) and comparable to the reported catalysts to date. For example, the turnover frequency of M( 10 )@BMC6 was 61.1 h ˗1 and ∼10 times that of Co/activated carbon. Additionally, the good reactivity of M( 10 )@BMC6 with adequate reusability might be understood by the good dispersion of small Co-nanoparticles. Importantly, dominant role of the doped N-species on carbon, by enhancing the synergy between Co- and N-species, was firstly suggested in this study. Finally, incorporation of N-sites in the carbon support for Co-nanoparticles can enhance the ODS performance, thus being suggested as an effective way to develop oxidation catalysts with outstanding performance. • Melamine incorporated bimetallic-azolate framework-6s were firstly prepared. • Co-nanoparticles well dispersed on N-enriched carbon were prepared from melamine/MOF. • Oxidative desulfurization (ODS) activity was increased by N-dopant on the carbon support. • The reusable M( 10 )@BMC6 had ∼ 10 times that of Co/activated carbon in ODS. • ODS reaction was explained with the facile formation of ⋅OH or 1 O 2 because of Co and N.

Design of a new synthetic nanocatalyst resulting high fuel quality based on multiple supports: experimental investigation and modeling

Abstract In order to meet the environmental legislations related to sulfur content, it is important to find an alternative techniques for deep removal of sulfur components from fuels. So, in this study, a novel nano-catalyst based on iron oxide (Fe2O3) as active component prepared over composite support (γ-Alumina + HY-zeolite) is developed here for efficient removal of sulfur compounds from fuel via oxidation process. The precipitation method is employed first to prepare the composite support and then the impregnation method is utilized to generate a novel synthetic homemade (Fe2O3/composite support) nanocatalysts that has not been developed in the literature (iron oxide over composite support). The characterizations of the prepared catalysts display that the surface area of the catalyst increases with increasing the amount of Y-zeolite in composite support. The effectiveness of the catalysts is tested by utilizing oxidative desulfurization (ODS) operation under several operating conditions. The results of the experimental work show that the activity of oxidative desulfurization enhances with increasing Y-zeolite, temperature, and batch time under moderate operating conditions. The oxidative desulfurization efficiency followed the order: CAT-1 < CAT-2 < CAT-3. The CAT-3 performed the high removal of sulfur compounds (90.73%) at 100 min and 423 K. The best values of the kinetic parameters of the ODS process are then determined based on experimental data and model based techniques within gPROMS package. Finally, the reactor model is used to determine the optimal operating conditions while maximizing the removal of sulfur compounds leading to cleaner fuel. Where, 99.3% of the sulfur removal has achieved at batch time of 190.6 min, temperature of 543.56 K and initial sulfur content at 0.8668 wt% in the presence of CAT-3 based on the optimal kinetic parameters (order of reaction (n) of 1.9865719, activation energy (EA) at 29.942 kJ/mol and pre-exponential factor (k 0) with 622.926 wt−0.9865719 min−1).

Green and efficient oxidative desulfurization of refractory S-compounds from liquid fuels catalyzed by chromium-based MIL-101 stabilized MoOx catalyst

In this work, MoOx/MIL-101(Cr) a new composite material, involving the collaboration of MoOx and MIL-101(Cr) to remove the refractory S-compounds (RSCs) from fuels via oxidative desulfurization (ODS) process were successfully synthesized. The prepared catalyst was characterized by scanning electron microscopy (SEM), energy-dispersive spectroscopy (EDX), powder X-ray diffraction (P-XRD), inductively coupled plasma optical emission spectroscopy (ICP-OES), fourier transform infrared spectroscopy (FT-IR), N2 sorption measurement (BET) and X-ray photoelectron spectroscopy (XPS). The prepared MoOx/MIL-101(Cr) was applied for the ODS of model fuel oil and showed the remarkably catalytic activity for the removal of RSCs from model fuel oil via oxidation. In addition, the effect of Mo-loading amount, H2O2/sulfur (O/S) molar ratio, and reaction temperature on the ODS reactivity were investigated. To explore the specific reaction mechanism of ODS over the MoOx/MIL-101(Cr), the effect of radical scavengers on ODS activity was examined. The radical scavengers experiments showed that the present oxidation reaction occurred through a radical mechanism involving the formation of •OH and •O2͞ species. In addition, it was found that the ODS efficiency is majorly related to the Mo5+ species forming with electron transfer to Mo6+ ion from Lewis acid sites of MIL-101(Cr). Furthermore, the MoOx/MIL-101(Cr) catalyst possesses recycling performance and remarkable stability, and even after five recycles, the removal of DBT was >94.8%. Hence, it could be confirmed that MoOx/MIL-101(Cr) is very useful in the ODS to remove RSCs from fuels in the presence of H2O2.

Efficient pyridinium-based ionic liquid for deep oxidative desulfurization of model oil

The present research work reports the synthesis of a pyridinium-based ionic liquid (IL) 1-butyl-4-methylpyridinium benzoate [BMPy][(C6H5)COO]. Full characterization of [BMPy][(C6H5)COO] was then performed using 1H NMR, 13C NMR, FTIR, TGA, and elemental analysis. [BMPy][(C6H5)COO] was firstly applied in the extractive desulfurization (EDS) of a model oil consisting of dibenzothiophene (DBT) and dodecane (1000 ppm), where 63.1% DBT-removal efficiency was revealed under optimum conditions of 60 °C, 90 min, and a mass ratio of 1:1 (IL/model oil). To further improve the efficiency of DBT-removal, [BMPy][(C6H5)COO] was subsequently employed in oxidative desulfurization (ODS), where it acted as an extractant with H2O2 as an oxidant. Successfully, 98.9% of DBT was removed at 60 °C and within 90 min using an equal mass ratio of IL/model oil and molar ratio (8) of O/S. Moreover, [BMPy][(C6H5)COO] could be regenerated and recycled for five consecutive runs while retaining approximately the same ODS efficiency. A mechanism of ODS using [BMPy][(C6H5)COO] was proposed. The π–π interactions between IL's structure and DBT were suggested to be the driving force behind the extraction power of [BMPy][(C6H5)COO]. Furthermore, recommendations for future research directions of ODS using ILs were introduced. Finally, a comparison of ODS results for [BMPy][(C6H5)COO] and different pyridinium-based ILs for various model oils was conducted where [BMPy][(C6H5)COO] showed to be a competitive and promising type of pyridinium-based IL for use in the ODS processes.

Magnetic-heteropolyacid mesoporous catalysts for deep oxidative desulfurization of fuel: The influence on the amount of APES used

Magnetic-heteropolyacid mesoporous catalysts have been obtained, in which magnetic Fe3O4 in the center of MCM-41 mesoporous materials and APES (3-aminopropyl-triethoxysilane) used to link heteropolyacid. To noted, for the various molar ratio APES used in the synthesized process, different numbers of –OCH3 were exposed in the final products (zero, one and two), named Fe@MP-1, Fe@MP-2 and Fe@MP-3, respectively. Interestingly, the three kinds of catalysts exhibited the various DBT removal efficiency during the oxidative desulfurization process, mainly due to their structure variance leading to be the research focus in this work. Among them, under the oxygen in air as oxidant, Fe@MP-1, with no –OCH3 exposed outside, showed the excellent desulfurization activity with 100% DBT conversion in 90 min and behaved nearly no obvious decrease after at least 8 recycling times. Thus, the certain amount of APES, used to link active components with supporters, is suggested as an effective aspect to increase the oxidative desulfurization efficiency and maybe the different types of linkage also show the various influence, which will be focused on in our further researches.

Preparation of WO3/CNT catalysts in presence of ionic liquid [C16mim]Cl and catalytic efficiency in oxidative desulfurization

AbstractBACKGROUNDWith the strict regulation for environmental protection, the removal of sulfur compounds from fuels is becoming more and more urgent. Hydrodesulfurization is one of the most widely used technologies in chemical industry, but its application is limited because of the harsh reaction conditions and the low efficiency in removal of aromatic organic sulfide. In this work, catalysts consisting of tungsten trioxide immobilized on carbon nanotubes (WO3/CNT) in the presence of ionic liquid [C16mim]Cl were prepared for the oxidative desulfurization of aromatic organic sulfide.RESULTSThe catalysts were systematically characterized by TG‐DSC, XRD, UV–visible, FTIR, Raman, SEM, TEM, XPS and BET. The dispersion of CNT and the crystal phase of WO3 on the carrier (CNT) were changed in the presence of ionic liquid [C16mim]Cl. The WO3 exists in tetrahedral form when the mass ratio of [C16mim]Cl to CNT is 2. The WO3/CNT catalyst demonstrates better activity in the oxidative desulfurization system, with the removal of dibenzothiophene (DBT) reaching 90.73% under optimal conditions. The oxidation process of DBT follows pseudo‐first‐order kinetics, and the activation energy is about 29.69 kJ mol−1. Dibenzothiophene sulfone (DBTO2) was determined to be the oxidative product of DBT.CONCLUSIONThe results illustrated that the oxidative desulfurization efficiency of different forms of WO3 loaded on the same carrier (CNT) followed the order tetrahedral WO3 > tetragonal phase WO3 > monoclinic phase WO3. © 2019 Society of Chemical Industry

Composite Beads of Molybdenum Oxide Supported on Textured Silicon as an Oxidative Desulfurization Nanocatalyst

In the present work, Silicon powder was etched in the alkaline solution. The surface area of silicon powder increased after etching. Then, a nanocatalyst of molybdenum supported on textured silicon powder was successfully prepared. The nanocatalyst was characterized by scanning electron microscopy (SEM), Energy dispersive X-ray spectroscopy (EDS), Fourier transform infrared (FT-IR), X-ray diffraction (XRD), and N2 adsorption-desorption. Molybdenum particles were dispersed on the entire surface of textured silicon beads. The spherical granules of this nanocatalyst were prepared by polyvinyl alcohol. The experimental results showed that the high oxidative desulfurization efficiency of dibenzothiophene were achieved ~93.7% using MoO3/Si/PVA/H2O2 within 150 min and at 60 °C. The oxidation rate was fitted to the pseudo-first-order kinetic model. The beads could be easily separated from the reaction solution and reused for 5 times. The remarkable advantages of this approach is a green, low- cost, reusable and effective method for oxidative desulfurization.

A novel high-performance SnO2 catalyst for oxidative desulfurization under mild conditions

The catalyst SnO2 was prepared by a precipitation method, and then aged and calcined at the optimal temperature of 673 K. The reaction conditions were optimized and the oxidation desulfurization efficiency of the obtained catalyst were evaluated. The sulfur removal rate was 99.8% at the optimum reaction conditions of 0.08 g catalyst, 333 K, O/S = 10, 2 h. The catalytic site in the ODS process of the SnO2 catalyst may be Sn4+/Sn2+ Lewis acids. Furthermore, no significant catalytic performance decrease was observed over 14 reuse cycles. The excellent activity and reusability of the catalyst was attributed to the beneficial effects upon specific surface area and acidic-site strength of the appropriate heat treatment temperature.

Oxidative desulfurization of diesel fuel with caprolactam-based acidic deep eutectic solvents: Tailoring the reactivity of DESs by adjusting the composition

Despite the significance of hydrogen bonding in deep eutectic solvents (DESs) for desulfurization processes, little is understood about the relationship between the DES composition, hydrogen-bonding strength, and oxidative desulfurization activity. In this study, a new family of caprolactam-based acidic DESs was prepared with different molar ratios of caprolactam and oxalic acid. The prepared DESs were characterized by differential scanning calorimetry, Fourier transform infrared spectroscopy, 1H nuclear magnetic resonance, and thermogravimetric analyses. These DESs were employed for oxidative desulfurization reactions and the desulfurization efficiency was found to vary regularly with the DES composition. The factors influencing the removal of dibenzothiophene were systematically investigated and the desulfurization efficiency of the caprolactam-based acidic DESs reached as high as 98% under optimal conditions. The removal of different sulfur compounds followed the order: dibenzothiophene > 4,6-dimethyldibenzothiophene > benzothiophene. The combined experimental data and characterization results revealed that the oxidative desulfurization efficiency of the system was influenced by the hydrogen bonding interactions with the DES, which can be optimized by adjusting the DES composition. These findings regarding hydrogen bonding in DESs provide new insight for better understanding of the mechanism of diesel deep desulfurization processes.

Improving the Catalytic Performance of Keggin [PW12O40]3- for Oxidative Desulfurization: Ionic Liquids versus SBA-15 Composite.

Different methodologies were used to increase the oxidative desulfurization efficiency of the Keggin phosphotungstate [PW12O40]3− (PW12). One possibility was to replace the acid proton by three different ionic liquid cations, forming the novel hybrid polyoxometalates: [BMIM]3PW12 (BMIM as 1-butyl-3-methylimidazolium), [BPy]3PW12 (BPy as 1-butylpyridinium) and [HDPy]3PW12 (HDPy as hexadecylpyridinium. These hybrid Keggin compounds showed high oxidative desulfurization efficiency in the presence of [BMIM]PF6 solvent, achieving complete desulfurization of multicomponent model diesel (2000 ppm of S) after only 1 h, using a low excess of oxidant (H2O2/S = 8) at 70 °C. However, their stability and activity showed some weakness in continuous reused oxidative desulfurization cycles. An improvement of stability in continuous reused cycles was reached by the immobilization of the Keggin polyanion in a strategic positively-charged functionalized-SBA-15 support. The PW12@TM–SBA-15 composite (TM is the trimethylammonium functional group) presented similar oxidative desulfurization efficiency to the homogeneous IL–PW12 compounds, having the advantage of a high recycling capability in continuous cycles, increasing its activity from the first to the consecutive cycles. Therefore, the oxidative desulfurization system catalyzed by the Keggin-type composite has high performance under sustainable operational conditions, avoids waste production during recycling and allows catalyst recovery.

Heteropolyacids supported on macroporous materials POM@MOF-199@LZSM-5: Highly catalytic performance in oxidative desulfurization of fuel oil with oxygen

A highly active catalyst Keggin type POM-based inorganic-organic compound POM@MOF-199@LZSM-5(PMZ) has been prepared and applied in the catalytic oxidative desulfurization system. Structure and properties of catalyst were characterized by X-ray diffraction (XRD), Fourier transform infrared (FT-IR), X-ray photoelectron spectroscopy (XPS), N2 adsorption-desorption, scanning electron microscopy (SEM), transmission electron microscopy (TEM) and so on. The catalyst gave high desulfurization activity in the removal of DBT using O2 as the oxidant. Under the optimal conditions, the conversion rate reached 100% only in 120 min. The kinetic studies revealed that the oxidative desulfurization can present a pseudo first-order kinetic process and the apparent activation energy was 30.5 kJ/mol. The response surface method also used to optimize the process of oxidative desulfurization. There was little change for the oxidative desulfurization efficiency after 10 recycle times. This enhanced catalytic performance could be attributed to the more filled active species, POM, in the larger porous materials and the good protection measures of dual-function porous material supports.

Phosphotungstic acid immobilized on amino functionalized spherical millimeter-sized mesoporous γ-Al2O3 bead and its superior performance in oxidative desulfurization of dibenzothiophene

The composite material HPW/NH2–Al2O3 was successfully prepared by immobilization of phosphotungstic acid H3PW12O40 (HPW) on the surface of amino functionalized spherical millimeter-sized mesoporous γ-Al2O3 beads (NH2–Al2O3), that featured high specific surface area, remarkable enhanced mechanical strength, chemical stability and low cost. This composite material was characterized by Fourier Transform Infrared Spectroscopy (FTIR), X-ray diffraction (XRD), Brunner−Emmet−Teller (BET) and mechanical strength measurements. The experimental results showed that introduction of NH2 group in between HPW and Al2O3 surface not only provide strong binding sites for catalytic centers HPW to get high dispersion on the carrier surface but also prevent HPW from structural decomposition. As a consequence, the prepared HPW/NH2–Al2O3 exhibited excellent catalytic performance in the oxidative desulfurization of model oil composed of dibenzothiophene (DBT) and n-octane. The 350ppmwS of sulfur content in 20mL of n-octane can be dropped down to 2.8ppmwS in 2h using 60mg of HPW/NH2–Al2O3 catalyst under the optimal conditions. Remarkably, the catalyst can be conveniently recycled by simple decantation method. After 10 times recycling, the oxidation desulfurization efficiency just dropped down slightly from 99.2% to 98.6%. The results indicate that synthesized HPW/NH2–Al2O3 beads have great potential as a catalyst in oxidative desulfurization for special practical applications.

Desulfurization of AL-Ahdab Crude Oil using Oxidative Processes

Two different oxidative desulfurization strategies based on oxidation/adsorption or oxidation/extraction were evaluated for the desulfurization of AL-Ahdab (AHD) sour crude oil (3.9wt% sulfur content). In the oxidation process, a homogenous oxidizing agent comprising of hydrogen peroxide and formic acid was used. Activated carbons were used as sorbent/catalyst in the oxidation/adsorption process while acetonitrile was used as an extraction solvent in the oxidation/extraction process. For the oxidation/adsorption scheme, the experimental results indicated that the oxidation desulfurization efficiency was enhanced on using activated carbon as catalyst/sorbent. The effects of the operating conditions (contact time, temperature, mixing speed and sorbent dose) on the desulfurization efficiency were examined. The desulfurization efficiency measured at the best operating conditions(optimum conditions): 60 , 500rpm, 60min contact time and sorbent dose of 0.7g AC/100 ml AHD crude, was 32.8% corresponding to a sulfur content of 2.6 wt%. Applying the same optimum operating conditions and at 3:1 solvent/oil ratio, the oxidation/extraction method gave comparable desulfurization efficiency of 31.5%.

Evaluation of nitrogen effect on ultrasound-assisted oxidative desulfurization process

A novel procedure based on ultrasound-assisted oxidative desulfurization was applied for diesel oil treatment, which was performed simultaneously to ultrasound-assisted oxidative denitrogenation (UAODN) in order to minimize N interference over S oxidation. The effect of ultrasonic irradiation time, reagent amount and the nature of extraction solvent were evaluated. A petroleum product feedstock containing quinoline was used as a model nitrogen compound and acetic acid and hydrogen peroxide were used as oxidizing agents. Nitrogen removal above 95% was obtained for the model oil after 5min of ultrasonic irradiation (20kHz, 750W, 40%). Additionally, this study showed that quinoline can reduce the oxidative desulfurization efficiency of an oil containing dibenzothiophene. The application of oxidative treatment without ultrasound showed that nitrogen and sulfur removal efficiencies for five diesel oil samples were considerably lower (lower than 22 and 40% for nitrogen and sulfur, respectively). The UAODN procedure was applied for the treatment of a hydrotreated petroleum product feedstock and samples of diesel oil with nitrogen and sulfur content up to 226 and 375mgkg−1, respectively. Under optimized conditions, nitrogen content below 20mgkg−1 was obtained and the feasibility of ultrasound for simultaneous denitrogenation and desulfurization was demonstrated.

Ultrasound field distribution and ultrasonic oxidation desulfurization efficiency

Ultrasonic oxidation desulfurization (UODS) has been considered a promising method for deeply desulfurization technology since it can be carried out using mild conditions. During the last few decades many experimental investigations have been carried out on optimizing the reaction condition such as ultrasonic irradiation time, oxidizing reagents amount, kind of organic acid and so on. But limited work has been reported on the influence of the ultrasonic cavitation field distribution. In this work, the relative intensity of the cavitation events has been measured with the aluminum foil erosion method in a commonly used ultrasonic cleaning vessel both in horizontal and vertical directions. The aluminum foil erosion image was then collected into computer by a scanner. In addition, the image processing program of MATLAB software was used to pretreat the erosion image and find out the positions of the erosion points so that the ratio of the erosion area to the entire area can be calculated which helped to quantify the measurement result since the erosion ratios was the representation of the cavitation intensity. The desulfurization efficiency was then measured in different position of the vessel. The results match well with the cavitation field distribution results which indicate that the cavitation field distribution can be used to guide the UODS process.

Catalytic kinetics of oxidative desulfurization with surfactant-type polyoxometalate-based ionic liquids

Surfactant-type polyoxometalate-based ionic liquids (SPILs), such as [(n-C8H17)3NCH3]3{PO4[MoO(O2)2]4}, [(n-C12H25)3NCH3]3{PO4[MoO(O2)2]4}, [(n-C8H17)3NCH3]3{PO4[WO(O2)2]4} and [(n-C12H25)3NCH3]3{PO4[WO(O2)2]4} have been investigated on their oxidative desulfurization. SPILs were very promising for the desulfurization of DBT in the model oil using H2O2 as the oxidant. Supposed mechanism and kinetics studies on the catalytic avtivity of SPIL [(n-C8H17)3NCH3]3{PO4[MoO(O2)2]4} revealed that the oxidative desulfurization of organosulfur compounds could present a pseudo first-order kinetic. The reaction rate constant and half-life of DBT oxidation were calculated. Moreover, the catalytic activity for other sulfur-containing compounds increased in the order BT<4, 6-DMDBT<DBT. There is little change for the oxidative desulfurization efficiency of SPIL after 8 recycles. And this work offers an alternative for oxidative desulfurization of actual prehydrotreated fuel as well.

Effect of various sono-oxidation parameters on the desulfurization of diesel oil

The influences of ultrasonic intensity, H2O2 concentration, ratio of H2O2 to oil and the addition of Fenton reagent on the oxidative desulfurization of diesel oil under ultrasonic irradiation were investigated. It was observed that the oxidative desulfurization of diesel oil fitted pseudo-first-order kinetics under our experimental conditions. Increasing the ultrasonic intensity increased the oxidative desulfurization efficiency of diesel oil. The addition of H2O2 enhanced the ultrasonic oxidative desulfurization efficiency of diesel oil. The sono-oxidation treatment in combination with Fenton reagent showed a synergistic effect for diesel oil desulfurization. The catalytic oxidative desulfurization process under ultrasonic irradiation process on diesel oils is an efficient and promising method.

An oxidative desulfurization method using ultrasound/Fenton's reagent for obtaining low and/or ultra-low sulfur diesel fuel

The total development trend in the world is towards continuously lower of sulfur content as a quality standard of diesel fuels. Integrating of an oxidative desulfurization unit with a conventional hydrotreating unit can bring benefits to producing low and/or ultra-low sulfur diesel fuels. Using the hydrotreated Middle East diesel fuel as a feedstock, four processes of the oxidative desulfurization have been studied: a hydrogen peroxide–acetic acid system and a Fenton's reagent system both without/with ultrasound. Results showed that the oxidative desulfurization reaction mechanics fitted apparent first-order kinetics. The addition of Fenton's reagent could enhance the oxidative desulfurization efficiency for diesel fuels and sono-oxidation treatment in combination with Fenton's reagent shows a good synergistic effect. Under our best operating condition for the oxidative desulfurization: temperature 313 K, ultrasonic power 200 W, ultrasonic frequency 28 kHz, Fe 2+/H 2O 2 0.05 mol/mol, pH 2.10 in aqueous phase and reaction time 15 min, the sulfur content in the diesel fuels was decreased from 568.75 μg/g to 9.50 μg/g.