Desulfurization Of Dibenzothiophene Research Articles

Biodesulfurization of Dibenzothiophene and Its Alkylated Derivatives in a Two-Phase Bubble Column Bioreactor by Resting Cells of Rhodococcus erythropolis IGTS8

Biodesulfurization (BDS) is considered a complementary technology to the traditional hydrodesulfurization treatment for the removal of recalcitrant sulfur compounds from petroleum products. BDS was investigated in a bubble column bioreactor using two-phase media. The effects of various process parameters, such as biocatalyst age and concentration, organic fraction percentage (OFP), and type of sulfur compound—namely, dibenzothiophene (DBT), 4-methyldibenzothiophene (4-MDBT), 4,6-dimethyldibenzothiophene (4,6-DMDBT), and 4,6-diethyldibenzothiophene (4,6-DEDBT)—were evaluated, using resting cells of Rhodococcus erythropolis IGTS8. Cells derived from the beginning of the exponential growth phase of the bacterium exhibited the highest biodesulfurization efficiency and rate. The biocatalyst performed better in an OFP of 50% v/v. The extent of DBT desulfurization was dependent on cell concentration, with the desulfurization rate reaching its maximum at intermediate cell concentrations. A new semi-empirical model for the biphasic BDS was developed, based on the overall Michaelis-Menten kinetics and taking into consideration the deactivation of the biocatalyst over time, as well as the underlying mass transfer phenomena. The model fitted experimental data on DBT consumption and 2-hydroxibyphenyl (2-HBP) accumulation in the organic phase for various initial DBT concentrations and different organosulfur compounds. For constant OFP and biocatalyst concentration, the most important parameter that affects BDS efficiency seems to be biocatalyst deactivation, while the phenomenon is controlled by the affinities of biodesulfurizing enzymes for the different organosulfur compounds. Thus, desulfurization efficiency decreased with increasing initial DBT concentration, and in inverse proportion to increases in the carbon number of alkyl substituent groups.

Study on the Reaction Mechanism of Oxidative Microbial Desulfurization of Organic Sulfur-Rich Coal

The present work deals with the use of iron/sulfur-oxidizing bacterium Acidithiobacillus ferrooxidans for the desulfurization of a coal sample from Assam, India. The coal sample contains 3.87% w/w of organic sulfur, 1.4% w/w pyritic sulfur, and 1.29% w/w of sulfate sulfur which altogether are contributing to its total sulfur content of 6.56% w/w. The microbial process followed the oxidative-desulfurization mechanism for the removal of sulfur from the coal sample. The bacterium performed cleavage of the sulfide bonds in pyrite to release the inorganic sulfur. Mass spectroscopic analysis revealed that the bacterial strain A. ferrooxidans performed oxidative desulfurization of a model sulfur-containing organic compound dibenzothiophene to 2-hydroxy biphenyl through the formation of dioxy-dibenzothiophene. A. ferrooxidans cells played the catalytic role to release the sulfur present in organic and inorganic form in the coal sample. The microbial desulfurization process conducted in a shake flask scale (500 mL) removed about 79% of total sulfur from the coal sample in 14 days.

Unraveling the Role of Surface Termination in Ni2P(001) for the Direct Desulfurization Reaction of Dibenzothiophene (DBT): A Density Functional Theory (DFT) and Microkinetic Study

Achieving ultradeep desulfurization of transportation fuels dictates the removal of the last fragments of sulfur present in bulky refractory molecules such as dibenzothiophene (DBT). Improving the hydrodesulfurization (HDS) performance of the next-generation Ni2P catalyst is crucial; however, it is still unclear how a DBT direct desulfurization (DDS) reaction proceeds on different surface terminations of this material. This work aims at elucidating the influence of Ni3P-, Ni3P2-, and partially sulfided Ni3P2 (Ni3PS)-terminated surfaces of the Ni2P(001) crystal on the DDS reaction of DBT using density functional theory (DFT) computations. The scission of the first C–S bond in DBT was found to be kinetically hindered compared to the second C–S bond cleavage over the three surfaces owing to the highly stable structure of adsorbed DBT compared to the C12H9SH intermediate. Notably, the overall DBT desulfurization process is thermodynamically favorable only on the Ni3PS surface, due to the presence of the active phosphosulfide (Ni–P–S) phase. Microkinetic modeling was conducted to probe the reaction orders, apparent activation energy, and rate-controlling steps as a function of temperature. Notably, the ring-opening step of DBT, via the first C–S bond cleavage, is the rate-controlling step on Ni3P and Ni3PS surfaces, which is rationalized by the high energy barrier of this step. The activation energy of the reaction over the surfaces followed the order Ni3P < Ni3PS < Ni3P2. Compared to the bare Ni3P2 surface, the lower activation energy on the Ni3PS surface is explained by the destabilization effect of the reaction intermediates on the latter. Thus, the partially sulfided Ni3P2 provides a better model for the DBT desulfurization process than the fresh Ni3P2 surface.

Investigation of Ni, Co, and Zn promoters on Mo/HY modified zeolite for developing an efficient bimetallic catalyst for oxidative desulfurization of dibenzothiophene

Bimetallic Mo-M (M = Ni, Co, and Zn)/RHY supported catalysts were synthesized for oxidative desulfurization (ODS) of dibenzithiophene (DBT). Recrystallized HY zeolite (RHY) included a superior meso-porous structure (RHY) which is attractive for bulky dibenzothiophene (DBT) elimination. The facilities of M promoters on the Mo/RHY features and activity were investigated. Despite similar ionic radius, different electronegativity of Ni, Co, and Zn transition metals caused to different interaction with Mo and RHY zeolite. The results demonstrated that Ni influenced negatively on dispersion of Mo species over the support, while Co and Zn improved the dispersion. Ni interacted readily with framework Al, leading to extraction of Al, collapse of the zeolite structure, and more octahedral and crystalline Mo species. The formation of MoO3 crystals was inhibited by Zn and Co addition leading to improvement of Mo dispersion. Moreover, Zn- and Co-doped Mo/RHY exhibited higher Lewis acidic sites. The ODS activity decreased in the order of MoZn > MoCo > Mo > MoNi. UV–vis results approved that the most of Mo in the Zn doped sample was non-framework type which can well disperse over the external surface. Meanwhile, Co addition enhanced the tetrahedral Mo species incorporated into the zeolite framework. Allowing more exposed high active Mo species for ODS reaction by Zn promoter, the catalytic performance was boosted. The best catalyst, MoZn/RHY, exhibited 100% DBT removal (t = 30 min, T = 40 °C, catalyst/fuel = 10 g/L, O/S = 10, VSolvent/VOil = 1/2, DBT = 1000 ppm) and a high reusability in 4 consecutive recycles. The highest removal of indole as a nitrogen compound was also achieved by the introduced MoZn/RHY catalyst.

Oxidative desulfurization of dibenzothiophene and simultaneous adsorption of products on BiOBr-C3N4/MCM-41 visible-light-driven core–shell nano photocatalyst

In this study, different amounts of BiOBr (x = 0, 5, 10, 15 wt%) and 5% wt. of g-C3N4 were loaded on MCM-41 as core for photo oxidation of DBT and simultaneous adsorption of oxidation products. Among studied photocatalysts, the BiOBr-C3N4/MCM-41 photocatalyst with 10% wt. of BiOBr indicated the highest activity so that this sample reduced DBT concentration to the lowest value of C/C0 = 0.08 after 150 min irradiation of visible light. The characterization of the as prepared photocatalysts by XRD, FESEM, TEM, FTIR, BET-BJH, UV–Vis DRS, and PL analyses revealed that this achievement was due to the highest amount of structural defects and the strongest interaction between BiOBr-C3N4 shell and MCM-41 core in this sample. Moreover, this sample indicated the lowest recombination rate of charge carriers, the narrowest band gap, and high porosity that enhanced the photocatalytic efficiency. However, this sample lost 18% of initial activity after four successive cycles of photo oxidation-adsorption that based on FTIR and BET-BJH was because of plugging of pores by DBT sulfones.

Synthesis of two-dimensional TiO2@multi-walled carbon nanotube nanocomposites as smart nanocatalyst for ultra-deep oxidative desulfurization of liquid fuel: Optimization via response surface methodology

The novel heterogeneous catalysts of 2D-TiO2@MWCNT nanocomposites are designed and synthesized via grafting TiO2 nanoparticles onto functionalized multi-walled carbon nanotubes and used for oxidative desulfurization of dibenzothiophene and real straight run light gas oil. The 2D-TiO2@MWCNT nanocomposite catalysts are completely characterized by FT-IR, Raman spectroscopy, XRD, TEM, NH3-TPD, ICP, and N2 adsorption–desorption isotherms. At first, the effect of various loading Ti on the MWCNT for ODS efficiency was investigated. The results revealed that 2D-0.6TiO2@MWCNT had the highest sulfur removal for the model, and SRLGO fuel compared to the other catalyst. Then, the optimal design of experiments using Box–Behnken experimental design was used to evaluate the effects of individual process variables such as temperature, O/S molar ratio, time, catalyst dosage, and their optimum values were found to be 69 °C, 46 min−1, O/S molar ratio: 9, and 0.03 g cat (25 ml DBT model fuel with 500 ppm S or 25 ml SRLGO with 12500 ppm S, 25 ml of acetonitrile), to achieve a high removal sulfur efficiency for DBT model oil (100%) and SRLGO (97.5 %), respectively. Based on optimal conditions, the 2D-0.6TiO2@MWCNT catalyst possesses superior catalytic activity and excellent reusability. The desulfurization reaction could be recycled for at least nine cycles without considerable reduction of catalytic performance, showing the good stability of the nanocomposite catalysts. An empirical kinetic model was applied to explain the rate data. Also, 2D-0.6TiO2@MWCNT nanocomposite catalyst had the lowest activation energy (27.65 Kj.mol−1) with the highest turnover frequency (16.15 h−1, around 2–3 times of the best catalyst so far) in desulfurization reactions compared to any TiO2-based catalysts. Furthermore, the catalytic reaction mechanism is investigated.

8-Hydroxyquinoline functionalized titanium-oxo clusters for visible-light-driven photocatalytic oxidative desulfurization

The 8-hydroxyquinoline functionalized titanium-oxo clusters (TOCs) of the formulation [Ti9(μ3-O)7(μ2-O)3(μ2-OiPr)(OiPr)5(O2CtBu)9(OQ)]·HOiPr (HOQ = 8-hydroxyquinoline) and [Ti12(μ3-O)8(μ2-O)6(μ2-OiPr)2(OiPr)4(O2CtBu)12(OQ)2]·4H2O were synthesized and structurally characterized by single-crystal X-ray diffraction. The assembly mode between the {Ti3(μ3-O)} and {Ti6(μ3-O)6} building units in the clusters has been rarely observed for titanium-oxo clusters. These two clusters exhibit intense visible absorption with narrow band gap of ~2.4 eV due to the presence of 8-hydroxyquinoline ligands. The clusters exhibit favorable catalytic activity for the visible-light-driven photocatalytic oxidative desulfurization (PODS) of dibenzothiophene. The results demonstrate that the core structure and functional ligands are important for the photocatalytic activity of titanium-oxo clusters.

Oxidative desulfurization of dibenzothiophene by magnetically recoverable polyoxometalate-based nanocatalyst: Optimization by response surface methodology

Abstract This research investigates the catalytic activity of a new core-shell structured nanocatalyst, which was prepared by surface modification of magnetic silica nanoparticles with Keplerate nano-porous molybdenum oxide-based polyoxometalate ({Mo132}), in oxidative desulfurization (ODS) of dibenzothiophene (DBT) in n-octane as simulated fuel (SF). The characterization of the as-prepared catalyst was performed by several methods including XRD, FTIR, VSM, TEM, HRTEM, SEM/EDS, HAADF-STEM EDX line scan, ICP-OES, and CHNS analysis. The optimization process and design of experiments were performed by response surface method with the principles of central composite design (CCD). The effects of reaction conditions including temperature (X1), O/S molar ratio (X2), and concentration of the catalyst (X3) were assessed on DBT removal efficiency. The statistical results showed that temperature was the most effective parameter in the process. Meanwhile, optimal conditions for DBT removal were attained when the dosage of the catalyst, O/S molar ratio, and temperature were 0.0074 g cat. g-1 SF, 20.7, and 58 oC, respectively. Moreover, a sulfur removal of 99.94% was obtained for SF using the prepared catalyst within 30 min under the optimal reaction conditions. The recovery of catalysts from the reaction medium was done with a magnet and the performance of the recovered catalyst showed no loss in activity after four test runs.

Reactive Adsorption Desulfurization of Dibenzothiophene in Presence of Mesoporous Adsorbents

Reactive Adsorption Desulfurization of Dibenzothiophene in Presence of Mesoporous Adsorbents

Experimental and theoretical study of deep oxidative desulfurization of Dibenzothiophene using Oxalate-Based catalyst

The present study reports the experimental and theoretical investigation for production of ultra-low sulfur liquid fuels through estimation of various reactive species formed during the reaction with the help of simulation. All the experiments were performed using an ultrasound bath which operates at a frequency of 37 kHz and a theoretical power of 95 W. The presented oxalate-based technique is found to be more efficient with > 93% DBT oxidation within 15 min of reaction time at 25 °C due to formation of reactive species like FeIIC2O4 and FeIIC2O422- which accelerate the reaction kinetics. Moreover, we have also investigated the influence of process parameters such as molar ratio of C2O42-/Fe2 +, oxidant concentration, volume ratio of organic to aqueous phase, sulfur concentration, and activation methods of oxidant. The results revealed that catalyst can be reused for several runs without decrease in catalytic activity. The experimental and simulation of cavitation bubble dynamics results revealed that sonochemical effect assists to accelerate the reaction kinetics through formation of free radicals (•O, •H, •OH and HO2∙) and other reactive species like O3 and H2O2 generated during transient cavitation. The sono-physical effects of cavitation help to create a fine emulsion in the liquid–liquid heterogeneous system leading to enhanced mass transfer rate by providing more interfacial surface area for occurring chemical reaction.

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.

Oxidation Adsorptive Desulfurization of Jet Fuel Using Mesoporous Sieve Loaded with TiO2

AbstractHerein we report a simple process involving catalytic adsorptive desulfurization (CADS) of model jet fuel under mild conditions with H2O2 using TiO2 loaded on MCM‐41, SBA‐15, or multi‐walled carbon nanotubes (MWCNTs) prepared by ultrasonic assisted initial wetting impregnation. The removal of dibenzothiophene (DBT) was investigated in terms of the oxygen/sulfur ratio, temperature, loading capacity, competitive components and adsorption kinetics. The adsorption capacity and adsorption strength of TiO2/MCM‐41 were higher than those of TiO2/SBA‐15, which are related to the higher SBET of MCM‐41, or the presence of numerous silanol groups. The TiO2/MWCNTs also showed excellent DBT adsorption capacities. TiO2/MCM‐41 exhibited better selectivity toward the oxidative‐adsorptive desulfurization of DBT owing to the weak influence of competitive adsorption of aromatics; this was explained by the lack of micropores in the one‐dimensional mesoporous structure. The sample with 1 % TiO2/MCM‐41 showed a high DBT adsorption capacity and rapid kinetics, and thus proved to be an inexpensive and effective desulfurization adsorbent for producing clean jet fuel.

Deep oxidative desulfurization of dibenzothiophene by novel POM-based IL immobilized on well-ordered KIT-6

A novel POM-based IL immobilized on well-ordered KIT-6 catalyst [Omim] 3 PMo 12 O 40 /KIT-6 was successfully synthesized. Complete desulfurization (100%) can be achieved within 80 min for DBT model oil (S: 1000 ppm) under 60 °C and O/S = 5 using tertbutyl hydroperoxide (TBHP) as an oxidant. The hydroxyl radicals (•OH) was proved to be the most important reactive species by a scavenger experiment. The synergistic effect of super catalytic ability of [PMo 12 O 40 ] 3− Keggin structure and the absorption ability of KIT-6 and [Omim] + contributes to the excellent S conversion rate. • A novel catalyst [Omim] 3 PMo 12 O 40 /KIT-6 was synthesized by impregnation method. • Desulfurization efficiency of 100% can be achieved within 80 min for dibenzothiophene model oil (S: 1000 ppm). • Different substrates were used as reactants and the oxidation activity decreases in the order of DBT > 4,6-DMDBT > BT. • The hydroxyl radicals (•OH) played an indispensable role in oxidative desulfurization. • The synergistic effect of [Omim] + , PMo 12 O 40 3- and KIT-6 contributes to the excellent catalytic activity. Oxidative desulfurization (ODS) process is one of the most promising desulfurization technologies because of its energy-efficient and mild operation condition. In this study, a novel active phase POM-based IL-[Omim] 3 PMo 12 O 40 was synthesized, and then it was supported on well-ordered KIT-6. [Omim] 3 PMo 12 O 40 /KIT-6 catalyst was used in the dibenzothiophene (DBT) and real diesel oxidative desulfurization with tertbutyl hydroperoxide (TBHP) as an oxidant. The composite materials [Omim] 3 PMo 12 O 40 and [Omim] 3 PMo 12 O 40 /KIT-6 catalysts were characterized by means of Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), scanning electron microscope (SEM), transmission electron microscopy (TEM), X-ray photo-electron spectroscopy (XPS) and nitrogen adsorption–desorption analysis. [Omim] 3 PMo 12 O 40 /KIT-6 catalyst showed high catalytic activity, at the optimal conditions of m catalyst /V Oil = 0.1 g/20 ml, m [Omim]3PMo12O40 /m KIT-6 = 30%, O/S = 5 (molar ratio), 60 °C, S of 1000 ppm (DBT in n-octane) can be completely removed within 80 min due to the superior mass transfer ability of the cubic I a 3 _ d mesoporous structure of KIT-6 and excellent catalytic ability of [Omim] 3 PMo 12 O 40 . In addition, [Omim] 3 PMo 12 O 40 /KIT-6 could be easily separated and the catalytic activity remains stable after 9 cycles. The ODS reaction mechanism is also investigated.

Sequential Post-Synthetic Modification and Evaluation of Catalytic Activity of Hierarchically Porous Sulfated Geopolymer in the Oxidative Desulfurization of Dibenzothiophene

A novel sulfated hierarchically porous geopolymer catalyst for the oxidation of dibenzothiophene was prepared through sequential treatment with desilication, ion-exchange and sulfation techniques. Desilication and ion-exchange treatments were aimed at the creation of hierarchical porosity and controlling the surface area of the geopolymer, while sulfation treatment was primarily done to enhance the acidity of the hierarchically porous geopolymer. The properties of the catalyst obtained after the modifications was studied by BET, NH3-TPD, SEM, TEM, XRD, FTIR and XRF analyses. As a result of the proposed sequential treatment, the activity of the geopolymer towards the oxidation of dibenzothiophene was profoundly increased and reflected in the enhanced conversion from 14 to 85%. A plausible electronic mechanism proposed for the reaction accentuated that the reaction might take place in two stages: the formation of sulfated geopolymer peroxo complex as the active catalyst and nucleophilic attack by dibenzothiophene over the peroxo complex to form the product, both were elaborated with suitable kinetic model. The interaction between dibenzothiophene and peroxo complex was considered to be of primary concern, based on which, Langmuir–Hinshelwood kinetic model was developed. Effective regeneration upto three cycles emphasized its potential to be exploited as an efficient catalyst for oxidative desulfurization.

Titanium-rich TS-1 zeolite for highly efficient oxidative desulfurization

The exploration of highly efficient catalysts based on nano-sized Ti-rich titanosilicate zeolites with controllable active titanium species is of great importance in zeolite catalytic reactions. Herein, we reported an efficient and facile synthesis of nano-sized Ti-rich TS-1 (MFI) zeolites by replacing tetrabutyl orthotitanate (TBOT) with tetrabutyl orthotitanate tetramer (TBOT-tetramer) as the titanium source. The introduced TBOT-tetramer slowed down the zeolite crystallization process, and accordingly balanced the rate of incorporating Ti and the crystal growth and inhibited the massive formation of anatase species. Notably, the prepared Ti-rich TS-1 zeolite sample had a Si/Ti as low as 27.6 in contrast to conventional one with a molar ratio of 40. The TBOT-tetramer endowed the titanosilicate zeolites with enriched active titanium species and enlarged external surface area. It also impeded the formation of anatase species, resulting in superior catalytic behavior toward the oxidative desulfurization of dibenzothiophene compared with the conventional TS-1 zeolite counterpart prepared with TBOT.

Kinetics and isothermal evaluations of adsorptive desulfurization of dibenzothiophene over mixed bio-wastes derived activated carbon

ABSTRACT An equivalent blend of date pits and olive stones (w/w) was employed as a low-cost precursor for activated carbon (AC) synthesis by the ZnCl2 activation method. Field Emission Scanning Electron Microscopy (FESEM), surface area (BET), X-ray diffraction, Fourier Transform Infra-Red spectroscopy (FTIR), Thermal Gravimetric Analysis (TGA), and the titration method were implemented in the diagnosis of the AC. The adsorptive action of the synthesized AC was inspected toward the desulfurization of dibenzothiophene (DBT). The maximum % removal of DBT reached 92.86% under optimum conditions of 0.30 g of the AC, a contact period of 60 minutes, at 40°C, and 25 mL of 200 mg/L DBT solution. The adsorption data followed the pseudo-second-order kinetic model, while Freundlich isotherm model described best the adsorption data. The desulfurization study of the commercial gasoline through applying the best conditions gave a removal efficiency of 46.66% compared to 92.86% for the model gasoline. In conclusion, the present investigation presents a cheap and effective adsorbent for both model and commercial gasoline fuel desulfurization.

Ultra-Deep Oxidative Desulfurization of Fuel with H2O2 Catalyzed by Mesoporous Silica-Supported Molybdenum Oxide Modified by Ce

A mesoporous silica-supported molybdenum oxide catalyst with a cerium(Ce) modifier was prepared by in situ synthesis and used in a hydrogen peroxide (H2O2) system for the desulfurization of dibenzothiophene (DBT), benzothiophene (BT), and 4,6-dimethyldibenzothiophene (4,6-DMDBT) fuel oils. The catalytic performance of the catalyst was studied. The catalyst was characterized by Fourier Transform Infra-Red (FT-IR), X-ray diffraction (XRD), Brunner−Emmet−Teller (BET), and X-ray Photoelectron Spectroscopy (XPS). The influences of m(catalyst)/m(fuel oil), v(H2O2)/v(fuel oil), reaction temperature, and reaction time were investigated. The catalyst had excellent catalytic oxidation desulfurization performance under moderate operational conditions. The catalytic performance was in the order DBT &gt; 4,6-DMDBT &gt; BT. The kinetic analysis results showed that the reaction was a pseudo first-order kinetics process and the apparent activation energies of DBT, BT, and 4,6-DMDBT were 46.67 kJ/mol, 56.23 kJ/mol, and 55.54 kJ/mol, respectively. The reaction products of DBT, BT, and 4,6-DMDBT were DBTO2, BTO2, and 4,6-DMDBTO2, respectively. The recycling experiments indicated that DBT, BT, and 4,6-DMDBT removal could still reach levels of 94.0%, 63.0%, and 77.9% after five cycles.

Ti-grafted MIL-101 as hydrophilic catalyst for efficient oxidative desulfurization of dibenzothiophene with hydrogen peroxide

Ti-containing porous materials are extensively studied in liquid-phase oxidative desulfurization (ODS) to obtain low-sulphur fuel, these materials displayed excellent ODS performance co-operating with organic oxidants but relatively poor ability with H2O2, which is a green and cheap oxidant widely used in industrial process. To overcome this challenge, we reported a H2O2 compatible ODS catalyst Ti-MIL-101 by treating MIL-101 with TiCl4 in dehydrated CH2Cl2. The results of N2-absorption, UV–vis, IR and XPS indicated that Ti species were mainly confined in mesopore cages of MIL-101 in the form of isolated and oligomeric octahedral Ti which were grafted to Cr centres of MIL-101 by Cl bridge. Moreover, wettability studies further suggested this catalyst possessed good affinity with water-based substance. As a result, Ti-MIL-101 exhibited efficient ODS ability in the oxidative reaction of DBT with H2O2 compared with that with organic oxidant. In model fuel, sulphur content was reduced to less than 10 ppmw from 1000 ppmw within 30 min at 333 K and the corresponding TOF value over Ti-MIL-101 reached 16.8 h−1. This outstanding catalytic ability might be the result of the synergy between the distinct active Ti species and the good surface affinity of Ti-MIL-101. Ti-containing metal–organic frameworks were prepared for oxidative desulfurization of obstinate sulphur compounds with H2O2. This catalyst displayed highly efficient activity in ODS of DBT. The sulphur content was reduced from 1000 ppmw to less than 10 ppmw in 30 min, corresponding TOF number reached 16.8 h−1. This outstanding catalytic result could be attributed to the superior affinity between catalyst and oxidant.

Mixed oxides derived from layered double hydroxides of Ni and Co as photocatalysts for desulfurization of dibenzothiophene

The synthesis of cobalt–nickel mixed oxides with different ratios of Ni/Co was carried out by co-precipitation method and used as a photocatalyst in the removal of dibenzothiophene (DBT) from a gasoline model under visible light. The structure of the synthesized samples was analyzed by the XRD, FTIR, BET and EDX spectrum. Also, the morphology of the mixed oxides was investigated with SEM images. It was found that the particle size is in the range of 15–30 nm, and the shape of the particles was almost spherical and distinctly separate. The mixed oxides exhibited promising photocatalytic activity to remove dibenzothiophene under visible light. The process was optimized by the one-factor at a time method. The effects of different factors such as the type of photocatalyst, dibenzothiophene concentration, temperature and time on the dibenzothiophene removal process were investigated and the optimal conditions resulted in the DBT concentration of 150 ppm catalyzed by 0.2 Co–Ni (1:1) photocatalyst at 50 °C for 3 h. The results indicated that DBT was degraded to SO2 gas and Biphenyl during the photocatalytic desulfurization. Mechanism of photo-desulfurization of di-benzothiophene over Ni-Co LDH/oxide.

Efficient and reusable ordered mesoporous WO x /SnO2 catalyst for oxidative desulfurization of dibenzothiophene.

The oxidative desulfurization (ODS) of organic sulfur compounds over tungsten oxide supported on highly ordered mesoporous SnO2 (WOx/meso-SnO2) was investigated. A series of WOx/meso-SnO2 with WOx contents from 10 wt% to 30 wt%, were prepared by conventional wet impregnation. The physico-chemical properties of the WOx/meso-SnO2 catalysts were characterized by X-ray diffraction (XRD), N2 adsorption–desorption isotherms, electron microscopy, Fourier transform infrared spectroscopy (FT-IR), Raman spectroscopy, and the temperature-programmed reduction of hydrogen (H2-TPR). The characterization results indicated that these catalysts possessed mesoporous structures with uniform pores, high specific surface areas, and well-dispersed polyoxotungstate species on the surface of meso-SnO2 support. The ODS performances were evaluated in a biphasic system (model oil/acetonitrile, Sinitial = 2000 ppm), using H2O2 as an oxidant, and acetonitrile as an extractant. Dibenzothiophene (DBT) in the model oil was removed completely within 60 min at 50 °C using 20 wt% WOx/meso-SnO2 catalyst. Additionally, the effect of reaction temperature, H2O2/DBT molar ratio, amount of catalyst and different sulfur-containing substrates on the catalytic performances were also investigated in detail. More importantly, the 20 wt% WOx/meso-SnO2 catalyst exhibited 100% surfur-removal efficiency without any regeneration process, even after six times recycling.