Removal Of Dibenzothiophene Research Articles

Supported vanadium oxide catalyst over HY-zeolite-alumina composite fabricated by extrusion for oxidative desulfurization of dibenzothiophene

Despite the advantages of zeolite catalysts/carriers, the small pore size of HY zeolite causes diffusion limitations especially for bulky refractory sulfur compounds in oxidative desulfurization (ODS) of fuels. To overcome this restriction, extruded HY-zeolite/Alumina composites containing both micro and meso‑pores were successfully synthesized and used as an attractive carrier for the vanadium dispersion. Insights about the interactions between zeolite and alumina and their effects on the vanadium impregnation were given implementing different analysis approaches; BET, SEM-EDX, TEM, NH3-TPD, and UV-vis. Alumina particle piling created meso‑pores in the composites providing a positive impact on the ODS of bulky dibenzothiophene (DBT). Comparing to physical mixing of the alumina and zeolite, the extrusion approach notably enhanced the weak acid sites due to the removal/distorting tetrahedrally coordinated Al from the zeolite framework. A less increase in the strong acid sites was also resulted from the reaction of Al-OH in the alumina with the free Si-OH over the zeolite. The proposed catalyst (V/HYZ-Al(alumina/zeolite ratio=50%) exhibited an excellent DBT removal so that 1000 ppmw of DBT was eliminated completely under the optimal investigated conditions (T = 50 °C, O/(S+N)=12 mol/mol, time=90 min, Mcatalyst/Vfuel=10 g/L). The catalyst recyclability was proved to be acceptable during four examined successive ODS cycles.

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

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

Enhancing biodesulfurization by engineering a synthetic dibenzothiophene mineralization pathway.

A synthetic dibenzothiophene (DBT) mineralization pathway has been engineered in recombinant cells of Pseudomonas azelaica Aramco J strain for its use in biodesulfurization of thiophenic compounds and crude oil. This functional pathway consists of a combination of a recombinant 4S pathway responsible for the conversion of DBT into 2-hydroxybiphenyl (2HBP) and a 2HBP mineralization pathway that is naturally present in the parental P. azelaica Aramco J strain. This novel approach allows overcoming one of the major bottlenecks of the biodesulfurization process, i.e., the feedback inhibitory effect of 2HBP on the 4S pathway enzymes. Resting cells-based biodesulfurization assays using DBT as a sulfur source showed that the 2HBP generated from the 4S pathway is subsequently metabolized by the cell, yielding an increase of 100% in DBT removal with respect to previously optimized Pseudomonas putida biodesulfurizing strains. Moreover, the recombinant P. azelaica Aramco J strain was able to use DBT as a carbon source, representing the best characterized biocatalyst harboring a DBT mineralization pathway and constituting a suitable candidate to develop future bioremediation/bioconversion strategies for oil-contaminated sites.

Intermolecular interactions induced desulfurization/denitrification of oil with deep eutectic solvents

Deep eutectic solvents (DESs) have great potential for desulfurization/denitrification of oil. This work investigated the underlying effect of hydrogen bond acceptors (HBAs) in DESs on the extractive removal of quinoline, carbazole and dibenzothiophene (DBT) from oil on the basis of the intermolecular interactions. With the acid-base interaction, quinoline was almost completely removed (∼100 wt%) in the acidic DES solvents. Differently, the hydrogen-bonding interactions enable the effective removal of near-neutral carbazole (96.0 wt%) and DBT (92.6 wt%) with assistance of H2O2. The partial addition of metal chlorides as the HBAs could further increase the desulfurization efficiencies to 94.7 wt% in 40 min due to the coordination-bonding interactions. Density functional theory (DFT) results confirmed that the HBAs are capable of regulating the interactions between heteroatomic compounds (e.g., carbazole) and DES components by manipulating the intrinsic hydrogen-bonding interactions in DESs, which further determines the desulfurization/denitrification performance. For the purification of catalytic diesel, the H2O2-assisted desulfurization and denitrification efficiencies were 60.0–69.0 % and 62.0–65.0 %, respectively. The intermolecular interaction analysis examined here provides guidance to improve the desulfurization/denitrification efficiencies in green DES extractants.

Extractive desulfurization in microchannels with polyethylene glycol 400: An experimental study and mass transfer evaluation

Conventional methods for removing sulfur compounds show unsatisfactory performance, especially when treating aromatic compounds. Current studies have directed efforts to investigate extraction desulfurization (EDS) using microdevices to overcome this difficulty. These units are designed with micrometer-sized channels responsible for intensifying heat and mass transfer phenomena. When using EDS, an adequate choice of extraction solvent is essential and among the possibilities, an excellent candidate for extraction solvent is polyethylene glycol (PEG). The present work studied the extractive performance offered by microdevices and the aspects related to mass transfer intensification by adopting PEG 400 as an extraction solvent in the removal of dibenzothiophene. The identification of flow patterns was performed by digital image colorimetry, making it possible to estimate the specific interfacial area (as) and the overall mass transfer coefficient (KLas) more accurately. DBT decontamination behavior was investigated under different volumetric flow rates (71.74–326.58 μL/min), different microchannel lengths (1.0–2.0 m), and a fixed diameter of 0.5 mm. The best result achieved an extractive efficiency of 94.06%, corresponding to a volumetric flow rate of 107.30 μL/min, whose interfacial area and overall mass transfer coefficients related to the slug flow pattern were calculated as 453.69 m−1 and 0.0229 s−1, respectively.

A novel photocatalytic and photoelectrocatalytic system for oxidative desulfurization of model fuel using BiVO4@HKUST-1 composite in powder and deposited on fluorine-doped tin oxide

In this study, photocatalytic oxidative desulfurization (PODS), as well as a photoelectrocatalytic oxidative desulfurization (PEODS) process was used for ultra-desulfurization of a model fuel using BiVO4@HKUST-1 composite as the catalyst in powder and deposited form on a fluorine tin oxide glass. Accordingly, the metal–organic framework HKUST-1 was synthesized and modified by the addition of BiVO4 to form the BiVO4@HKUST-1 photocatalyst. The composite, as well as pristine BiVO4 and HKSUT-1 samples were used for oxidative desulfurization under catalytic, photocatalytic, and eletrophotocatalytic conditions. The best results were observed for the BiVO4@HKUST-1 composite under photocatalytic desulfurization. The effect of different parameters such as reaction time, temperature, oxidizing agent, extractant solvent, catalyst amount, and solvents was investigated. Under optimal conditions, the dibenzothiophene (DBT) removal reached 95% in the PODS system. In comparison between photocatalytic and photoelectrocatalytic systems, PEODS gave the same results at the lower time and lower amounts of oxidant and catalyst. The catalyst could be recycled and reused six times without a significant change in DBT removal.

Metal-free oxidative desulfurization with molecular oxygen by using N-enriched porous carbons derived from ionic liquid-loaded covalent-organic polymer

A microporous triazine polymer (MCTP) was prepared and loaded, for the first time, with an N-containing ionic liquid (IL) through a ship-in-a-bottle method. The composite material, IL@MCTP, was pyrolyzed under high temperature to get N-enriched carbonaceous materials. The obtained carbons (denoted ICDCs) were utilized as a metal-free catalyst for the aerobic oxidative desulfurization (ODS) of organic sulfur compounds like dibenzothiophene from a model fuel. The reactivity of ICDCs in ODS was dependent on the nitrogen content and porosity of the carbons. One selected material (ICDC(8)), because of high nitrogen content and adequate porosity, showed a remarkable performance in ODS or removal of dibenzothiophene with a very low activation energy of 23.7 kJ/mol. Radical scavenger experiments and ESR analysis revealed the important role of superoxide anion radicals (•O2−) in oxidation. A plausible reaction mechanism to suggest an important role of nitrogen species in ICDCs to activate O2 (via adsorption on C with a partial positive charge) was proposed. The ODS also can be carried out with air, and the catalyst was reusable for up to the fifth cycle by simple solvent washing. The ICDCs can be a competitive and environment-friendly (metal-free) ODS catalyst, especially using cheap oxidants like air or O2.

Photo-oxidative extractive desulfurization of dibenzothiofene over Fe2O3-CeO2 nanocomposites at visible light irradiation

This research represents the role of Fe2O3 loading (10–100%) to ceria on the simultaneous oxidative and extractive photo-desulfurization of dibenzothiophene (DBT) in the visible light range. The catalysts were characterized by several known analyses in photocatalysis. The results revealed the FexCeO1-xOy solid solution fabrication with Fe loading up to 20%. While, Fe2O3 segregation was indicated at the higher loading percent. The Fe15Ce85 catalyst exhibited the highest photocatalytic DBT removal of 94.4%. The optimum conditions of 0.15 g catalyst, 2:1 solvent/oil and 2:1 H2O2/S for 2 h were obtained. The Fe15Ce85 higher activity was attributed to the influenced textural and chemical properties induced by Fe/Ce solid solution fabrication. Also, the small band gap and red shift in visible light absorption assigned to the Fe-Ce nanocomposite are reasons for high activity. The desulfurization mechanism was also proposed.

Controlled synthesis of efficient NiWS active phases derived from lacunary polyoxometalate and the application in hydrodesulfurization

Efficient catalysts with abundant NiWS active phases for hydrodesulfurization (HDS) were prepared based on structural diversity as well as unique electrostatics property of lacunary Keggin polyoxometalates (POMs). Owing to super nucleophilicity and coordinative ability, the trivacant Keggin [PW9O34]9- (PW9) can accurately capture and anchor Ni2+ promoters into its skeleton to form nanosized Nix@PW9 molecule in impregnating solution, thereby achieving ultra-dispersion of Ni promoters, high Ni/W ratio, and atomic-scale Ni–W proximity. The superior structure of Nix@PW9 promoted the simultaneous reduction and sulfuration of Ni and W species, thus obtaining shorter slab length, less stacking number, highly efficient synergism, and high concentration of NiWS active phases. Therefore, the resulted S-NiPW9/Al2O3 catalyst exhibits efficient HDS activity for dibenzothiophene (DBT) removal compared to that of reference catalysts prepared from monovacant [PW11O39]7- (PW11), saturated [PW12O40]3- (PW12), and conventional oxide precursors. The structure-directing effects of oxidic POM precursors on the texture and performance of HDS active phases were revealed by employing a variety of characterization methods, including transmission Fourier transform infrared (TS-FTIR), attenuated total reflectance Fourier transform infrared (ATR-FTIR), ultraviolet–visible spectroscopy (UV–Vis), single crystal X-ray diffraction, H2 temperature programmed reduction (H2-TPR), CO adsorbed Fourier transform infrared spectroscopy (IR/CO), X-ray photoelectron spectroscopy (XPS) and high-resolution transmission electron microscopy (HRTEM). This POMs-based molecular methodology opens a new avenue to better understand the evolution behavior of precursors and the formation mechanism of active species during the preparation of catalysts.

Zeolitic imidazolate framework grafted by cobalt tungstate as an efficient photocatalyst for photocatalytic oxidative desulfurization of dibenzothiophene

In this research, novel nanohybrid of zeolitic imidazolate framework supported cobalt tungstate semiconductor (ZIF-67@CoWO4) with various CoWO4 loading ratios (from 0 to 30 %wt) has been fabricated as a visible-light-driven photocatalyst for dibenzothiophene (DBT) removal from model fuel. XRD, UV-DRS, FE-SEM, EDX, BET and VSM characterizations were used to analyze the fabricated nanocomposites. At specific experimental conditions (100 mg/l DBT in model fuel, photocatalyst dosage of 2 g/l, visible light irradiation time of 2 h and H2O2/DBT mole ratio of 8:1), the ZIF-67@(1 wt%)CoWO4 sample exhibited excellent photocatalytic oxidative desulfurization (PODS) activity (96.7%) between different prepared photocatalysts, The improved reaction performance of ZIF-67@(1%wt)CoWO4 heterostructure can be attributed to the reciprocal effects of the high adsorption capacity of ZIF-67, optical properties of CoWO4 nanoparticles and the high charges separation and transfer efficiencies. Besides, the ZIF-67@CoWO4 photocatalyst possesses good stability for PODS and can be reused for five reaction cycles without a significant activity loss, indicating that it might be very useful in the deep PODS of hydrocarbon fuel.

Desulphurisation of liquid fuel using adsorption onto bio-based activated carbon modified with chitosan and Fe ions

ABSTRACT Removal of sulphur and sulphur compounds from liquid fuel is one of the most critical issues in the environment and energy field due to its widespread use and destructive effects. The aim of this research is the use of a bio-based activated carbon modified with chitosan and Fe ions (AC/Fe/CH) to remove Dibenzothiophene (DBT) from iso-octane as fuel. The properties of this adsorbent were identified using BET, EDX-SEM, and FTIR analyses. The effect of operating parameters including initial concentration (C), adsorbent amount (m), and stirring speed (U) was optimised to reach maximum removal of DBT from iso-octane fuel using RSM methodology. The maximum removal percentage of DBT using AC/Fe/CH was 98.229%, and the optimal conditions were 0.05 g /25 mL of adsorbent, DBT concentration of 149 mg L−1, and stirring speed of 50 rpm. The improvement of adsorption ability is attributed to the modification and creation of iron cations and N+ ions onto the activated carbon surface. DBT is attracted by Fe cations adsorption centre via π-complexation and S-Fe bond and attracted by N+ adsorption centre via electrostatic forces. By analysing the kinetics data with various kinetics models, the result indicated that the pseudo-second-order kinetics model is consistent with the experimental data. The Langmuir model has higher compatibility than other models with the equilibrium data. The Modified activated carbon with chitosan and Fe has the maximum adsorption ability equal to 270 mg g−1. According to the obtained data, the prepared adsorbent (AC/Fe/CH) has the appropriate ability to separate DBT from liquid fuel.

Nanoarchitectonics of Copper Tungsten-Mesoporous Silica with a New Template for Photo Oxidative-Desulfurization of Dibenzothiophene

A novel CuWO4/SiO2 heterojunction catalyst was successfully synthesized using a new sulfonamide derivative. The physical characteristics of the prepared samples were investigated by TGA, XRD, FTIR, SEM, UV, PL, and XPS. The prepared catalysts were applied as a nano photocatalyst for photooxidative desulfurization of dibenzothiophene under visible light using hydrogen peroxide as an oxidant. The photocatalytic oxidative desulfurization performances of the prepared samples were investigated. Various factors as the reaction time, dibenzothiophene concentration, catalyst dose, and the oxidizing agent dose were also studied. The prepared photocatalyst has high desulfurization activity in the removal of DBT under mild conditions. Results showed that the CuWO4/SiO2 exhibited considerably higher activity than neat support SiO2. Such improved photocatalytic activity is mainly attributed to the efficient separation of photogenerated electron–hole pairs on CuWO4/SiO2 heterojunction. Moreover, the synergistic effects of this photocatalytic oxidation and the green oxidant hydrogen peroxide played an essential role in desulfurization. The reaction is pseudo-first-order and can reach 98.6% removal of dibenzothiophene after 70 min and 97.2% after four cycles.Graphical

Synthesis, characterization and application of organoclays for adsorptive desulfurization of fuel oil.

The present study encompasses the application of cost effective, organo-modified bentonite material for efficient desulfurization of model oil and real fuel. For the adsorptive desulfurization of oil, dibenzothiophene (DBT) was used as model compound. Various experimental parameters (time, temperature, adsorbent-amount and DBT concentration) were thoroughly investigated. The synthesized material was characterized via X-ray diffraction (XRD), X-ray Fluorescence (XRF), Scanning electron microscopy (SEM), Energy dispersive x-ray (EDX), Thermogravimetric analysis (TGA) and Fourier transform infrared spectroscopy (FT-IR). The modification exhibits the increase in interlayer spacing of clay as confirmed from XRD and modified material shows interesting morphology as compared to unmodified bentonite. The results showed that > 90% of DBT removal was achieved under optimized conditions for B-BTC, B-BTB and B-DSS and > 80% for B-BEHA, for model fuel oil which are greater than unmodified clay (< 45%). Additionally, the findings from desulfurization of real fuel oil declare that 96.76% and 95.83% removal efficiency was achieved for kerosene and diesel oil respectively, at optimized conditions and fuel properties follow ASTM specifications. The obtained findings well fitted with thermodynamic, isothermal (Langmuir) with adsorption capacity (70.8 (B-BTC), 66 (B-BTB), 61.2 (B-DSS) and 55.2 (B-BEHA) in mg/g) and pseudo-second-order kinetics. In thermodynamic studies, negative sign (Delta G^circ ) specifies the spontaneity whereas, left(Delta H^circ right) endothermic and positive sign (Delta S^circ ) show randomness after DBT adsorption onto organoclay.

Process Optimization for Catalytic Oxidation of Dibenzothiophene over UiO-66-NH2 by Using a Response Surface Methodology.

This research investigates the catalytic performance of a metal–organic framework (MOF) with a functionalized ligand—UiO-66-NH2—in the oxidative desulfurization of dibenzothiophene (DBT) in n-dodecane as a model fuel mixture (MFM). The solvothermally prepared catalyst was characterized by XRD, FTIR, 1H NMR, SEM, TGA, and MP-AES analyses. A response surface methodology was employed for the experiment design and variable optimization using central composite design (CCD). The effects of reaction conditions on DBT removal efficiency, including temperature (X1), oxidant agent over sulfur (O/S) mass ratio (X2), and catalyst over sulfur (C/S) mass ratio (X3), were assessed. Optimal process conditions for sulfur removal were obtained when the temperature, O/S mass ratio, and C/S mass ratio were 72.6 °C, 1.62 mg/mg, and 12.1 mg/mg, respectively. Under these conditions, 89.7% of DBT was removed from the reaction mixture with a composite desirability score of 0.938. From the results, the temperature has the most significant effect on the oxidative desulfurization reaction. The model F values gave evidence that the quadratic model was well-fitted. The reusability of the MOF catalyst in the ODS reaction was tested and demonstrated a gradual loss of activity over four runs.

Electronic state tuning over Mo-doped W18O49 ultrathin nanowires with enhanced molecular oxygen activation for desulfurization

Developing catalyst with abundant surface active sites is the core issue to achieve efficient catalytic oxidative desulfurization performance. In this work, Mo doped W18O49 ultrathin nanowires is fabricated through solvothermal method to provide plentiful low coordinated metal atoms around oxygen vacancies to trigger oxidative desulfurization reaction. As a non-stoichiometric oxide, the discorded lattice microstructure in W18O49 endows the formation of O vacancies neighboring low-valence W atoms, while the ultrathin structure ensure the fully exposure of surface atoms. Moreover, the doped Mo atoms will tune the surface atomic structure and electronic state of W18O49 nanowires, leading to the higher oxygen vacancy concentration and strengthened interaction with target sulfide molecules. Benefiting from these features, the higher molecular oxygen activation capacity can be realized over Mo-W18O49 nanowires to yield more superoxide radicals, making it with greatly improved oxidative desulfurization performance. The optimized 2 %Mo-W18O49 catalyst shows nearly 100% removal of dibenzothiophene within 5 h and maintain the good cycle stability. This work supply new insights for the design of catalytic sites towards selective catalytic oxidative desulfurization.

Facile Synthesis of a Novel Ni-WO3@g-C3N4 Nanocomposite for Efficient Oxidative Desulfurization of Both Model and Real Fuel.

The current study comprises the successful synthesis of a Ni-WO3@g-C3N4 composite as an efficient and recoverable nanocatalyst for oxidative desulfurization of both model and real fuel oils. The physiochemical characterization of the synthesized composite was confirmed via Fourier transform infrared spectroscopy, X-ray diffraction, scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy, and thermogravimetric analysis. SEM results showed that Ni-WO3 particles were well-decorated on the g-C3N4 surface with an interesting morphology as appeared on the surface like spherical particles. The obtained findings revealed that 97% dibenzothiophene (DBT) removal can be achieved under optimized conditions (0.1 g of the catalyst, 1 mL of an oxidant, 100 mg/L DBT-based model fuel, a time duration of 180 min, and a temperature of 40 °C). Additionally, the catalytic activity for real fuel was also investigated in which 89.5 and 91.2% removal efficiencies were achieved for diesel and kerosene, respectively, as well as fuel properties following ASTM specifications. A pseudo first-order kinetic model was followed well for this reaction system, and the negative value of ΔG was due to the spontaneous process. Additionally, the desulfurization study was optimized via a response surface methodology (RSM/Box–Behnken design) for predicting optimum removal of sulfur species by drawing three-dimensional RSM surface plots. The Ni-WO3@g-C3N4 proved to be a promising catalyst for desulfurization of fuel oil by exhibiting reusability of five times with no momentous decrease in efficiency.

Oxidative desulfurization using nanocomposites of heterogeneous phosphotungstic acid over natural zeolites; optimization by central-composite design

In this research, the phosphotungstic acid (PTA) was impregnated on natural zeolites of clinoptilolite (Clin), mordenite (Mord), ferrierite (Ferr), and natrolite (Nat) and was characterized by X-ray diffraction (XRD), Brunauer–Emmett–Teller (BET), field emission scanning electron microscopy (FESEM), transmission electron microscopy (TEM) and energy dispersive X-ray (EDX. The synthesized heterogeneous nanocomposites were used for oxidative desulfurization of dibenzothiophene (DBT). Among samples, PTA-Ferr has removed the most amount of DBT (82.02%) from model fuel and PTA-Nat, PTA-Clin, and PTA-Mord indicated 56.00%, 73.62%, and 67.05% removal of initial DBT, respectively. PTA-Ferr had a high surface area of 293.6 m2/g, agglomeration-free particles with an average size of 10.2 nm. To study the effect of operating parameters such as reaction time, reaction temperature and DBT concentration on the ODS activity of PTA-Ferr, a central composite design (CCD) was used. Optimized conditions for the highest DBT removal (94.39%) were obtained at a reaction time of 55 min, the temperature of 60 °C and a DBT concentration of 250 ppm.

Electronic structure regulation of CoMoS catalysts by N, P co-doped carbon modification for effective hydrodesulfurization

Extensive efforts have been devoting to remove sulfur from transportation fuels to protect the environment. Here we present the synthesis of highly efficient hydrodesulfurization (HDS) catalysts by loading Co/Mo sulfides on various carbon modified γ-Al2O3 substrates. The synthetic strategy features facile sequential impregnation and pyrolysis process. The morphology, surface property, and pore structure of the catalysts were characterized by various techniques, and the catalytic performance were evaluated by a fixed-bed hydrodesulfurization unit. The optimized CoMo/NPC@γ-Al2O3 showed superior dibenzothiophene (DBT) removal rates (99%) and kHDS value (5.12 × 10-7 mol g−1 s−1) than those of CoMo@γ-Al2O3 at a relatively low temperature of 280 °C, revealing the effective modulation of carbon backbone. This remarkable HDS activity originated from the high sulfidation degree as well as electron-rich Mo species, which was attributed to the electron donating effect by N, P co-doping in the carbon skeleton. In addition, after the carbon modification, the decreased acid sites in γ-Al2O3 support and the electron-rich Mo sulfide resulted in a high selectivity of direct desulphurization (DDS) pathway over hydrogenation (HYD), leading to significant hydrogen energy economy. The density functional theory (DFT) calculations confirmed that the electron-donating effect of NPC enhanced the dispersion of Mo species and weakened the Mo-O/Mo-S bonds, creating more active sites. This work provides an effective strategy for rational design and synthesis of highly-efficient HDS catalysts in practical industrial application.

Ce2(MoO4)3 as an efficient catalyst for aerobic oxidative desulfurization of fuels

Ce 2 (MoO 4 ) 3 was synthesized by a simple reflux method using cerium nitrate hexahydrate and ammonium molybdate as reactants. The as-prepared Ce 2 (MoO 4 ) 3 was characterized by Fourier transform infrared spectroscopy (FT-IR), X-ray diffraction (XRD), Scanning electron microscope (SEM), and X-ray photoelectron spectroscopy (XPS). The removal of dibenzothiophene (DBT) in model oil was studied using Ce 2 (MoO 4 ) 3 as catalyst and oxygen as oxidant. The reaction factors such as reaction temperature, amount of catalyst, and sulfide type on sulfur removal were researched. The results prove that both Ce 3+ and MoO 4 2- play significant role in the conversion from DBT to DBTO 2 . The Ce 2 (MoO 4 ) 3 catalyst has an excellent performance for the sulfur removal of DBT. Under the optimum reaction conditions, sulfur removal of 99.6% was obtained. After recycling five times, no significant loss in catalyst activity of Ce 2 (MoO 4 ) 3 . Mechanism of aerobic oxidative desulfurization was proposed based on the experiment of free radical capture and infrared characterization.

Bio-inspired strategy to enhance catalytic oxidative desulfurization by O-bridged diiron perfluorophthalocyanine axially coordinated with 4-mercaptopyridine

Developing efficient and environmentally friendly catalytic system is significant for the removal of sulfide in fuel. O-bridged diiron perfluorophthalocyanine/4-mercaptopyridine (FePcF16-O-FePcF16/4-Mpy) as a novel composite catalyst was designed and prepared by axial coordination. The catalyst characterization was conducted through ultraviolet–visible spectroscopy, fourier transform infrared spectroscopy, X-ray diffractometry, electrospray ionization–mass spectrometry and density-functional theory technology. A high-efficient extraction oxidative desulfurization system is composed of hydrogen peroxide (H2O2), the mixture of ethanol and water and FePcF16-O-FePcF16/4-Mpy. Notably, the coordination of 4-Mpy greatly enhanced the catalytic activity of FePcF16-O-FePcF16, 99.4% of the desulfurization rate was achieved in 20 min at 30 °C. The catalyst system was cycled 8 times without significantly reducing the removal of dibenzothiophene. Electron paramagnetic resonance and gas chromatography–mass spectroscopy proved the high-valent iron-oxo intermediates were the main active substances in the FePcF16-O-FePcF16/4-Mpy/H2O2 system, and the pathway of catalytic oxidation DBT was proposed. This work provided useful insights to select suitable ligands to improve the activity of metal phthalocyanine, and offered a novel idea for the construction of efficient oxidative desulfurization system.