Deep oxidative desulfurization of benzothiophene and dibenzothiophene with a peroxophosphotungstate–ionic liquid brush assembly

A novel, efficient and reusable heterogeneous catalytic assembly of peroxophosphotungstate held in an ionic liquid brush was synthesized and an extraction and catalytic oxidative desulfurization (ECODS) procedure was developed for a model oil of benzothiophene (BT) and dibenzothiophene (DBT) using 30 wt% hydrogen peroxide as terminal oxidant and methanol as solvent under mild conditions. Several factors that affect sulfur removal were investigated in detail. The highest sulfur removal can reach 100% for BT in 7 h at 70 °C when the molar ratio of H₂O₂, S and catalyst is 10:1:0.025. The sulfur removal for DBT can also reach 100% in 4 h at 50 °C with the same molar ratio of H₂O₂, S and catalyst. The experimental results demonstrate that this ECODS process has no apparent scale‐up effect. The catalyst can be easily recovered (via simple filtration) and recycled five times without a significant decrease in activity. Copyright © 2015 John Wiley & Sons, Ltd.     

Macroporous 3D carbon-nitrogen (CN) confined MoOx catalyst for enhanced oxidative desulfurization of dibenzothiophene

Macroporous 3D carbon doped with nitrogen confined Mo catalyst (MoO_x@CN) had been prepared by a facile one-step pyrolysis technique using silica as a template and was employed for oxidative desulfurization (ODS) of dibenzothiophene (DBT) in model fuel with H₂O₂ as oxidant. The effect of different operating conditions (i.e., reaction temperature and time, catalyst dosage, H₂O₂/DBT (O/S) molar ratio) were also systematic investigated. Under the optimal reaction condition, MoO_x@CN catalyst exhibited highly excellent ODS performance toward DBT, the highest sulfur removal efficiency can be up to 99.9% and sulfur content was wiped out from 800 ppm to 10 ppm. Due to the robust 3D structure promoting rapid transfer, in addition to the increased number of active sites induced by the Mo vacancies, the catalyst, prepared using chitosan and ammonium heptamolybdate in a mass ratio of 1:0.5, displayed rapid kinetics and low activation energy in the oxidation of dibenzothiophene. Moreover, it exhibited excellent recyclability after five cycles without any obvious decrease in catalytic activity for the oxidative desulfurization reaction.     

Desulfurization of model and real fuels by extraction and oxidation processes using an indenylmolybdenum tricarbonyl pre-catalyst

Regulations on the permissible levels of sulfur in transportation fuels are becoming ever more strict, with a global shift towards “zero sulfur” fuels, and the revamp of existing hydrodesulfurization (HDS) facilities to meet these lower caps is cost-prohibitive. Metal-catalyzed sulfoxidation chemistry is viewed as an economically viable desulfurization strategy that could complement conventional HDS technology. In the present work, the complex [η⁵-IndMo(CO)₃Me] ( 1 ) (Ind = indenyl) was employed in the catalytic oxidative desulfurization (CODS) of model and real liquid fuels, using aqueous hydrogen peroxide (H₂O₂) as oxidant. After optimization of the CODS reaction parameters (diesel/H₂O₂ ratio, catalyst amount, temperature), a high-sulfur (2000 ppm) model diesel containing benzothiophene, dibenzothiophene, 4-methyldibenzothiophene and 4,6-dimethyldibenzothiophene could be completely desulfurized within 2 hr under solvent-free conditions or in the presence of the ionic liquid 1-butyl-3-methylimidazolium hexafluorophosphate ([BMIM]PF₆) as extraction solvent. The catalyst formed under solvent-free conditions could be recycled without a significant decrease in desulfurization activity. The high performance of the CODS system was verified in the sulfur removal from a commercial untreated diesel fuel with a sulfur content of 2300 ppm, and a jet fuel with a sulfur content of 1100 ppm. Solvent-free CODS in combination with initial/final extraction gave desulfurization efficiencies of 70% for the diesel fuel and 55% for the jet fuel. CODS with [BMIM]PF₆ in combination with initial/final extraction led to a sulfur removal of 95.9% for the diesel fuel, which is one of the best results yet reported for ODS of commercial diesels.     

Synthesis and non-parametric evaluation studies on high performance of catalytic oxidation-extraction desulfurization of gasoline using the novel TBAPW11Zn@TiO2@PAni nanocomposite

In this work, the new catalyst (assigned as TBAPW₁₁Zn@TiO₂@PAni) was successfully designed and synthesized on the basis of quaternary ammonium salt of zinc monosubstituted phosphotungstate [(n-C₄H₉)₄N][PW₁₁ZnO₃₉] (TBAPW₁₁Zn), titanium dioxide (TiO₂), and polyaniline (PAni). This study reports the catalytic oxidation-extraction desulfurization (ECODS) of sulfur-containing molecules from real and the simulated (Th, BT, and DBT) gasoline using new organic–inorganic hybrid catalyst (TBAPW₁₁Zn@TiO₂@PAni). The ECODS results were shown that the concentration of sulfur compounds (SCs) of real gasoline was lowered from 0.4992 to 0.0122 wt.% with 97% efficiency at 35 °C after 1 h. Furthermore, the synthesized heterogeneous nanocatalyst showed high stability and reusability after five times without significant loss of activity. The high performance of TBAPW₁₁Zn@TiO₂@PAni/H₂O₂/CH₃CO₂H system can be a promising route with a superb potential in the generation of ultra-low-sulfur gasoline. Also the Mann–Whitney U-test results show that there is not a significant difference between the mean of sulfur percentage for DBT & BT, BT & Th and DBT & Th in the presence of the catalyst. Based on the Kruskal–Wallis test results, we can conclude that the temperature, time and amount of catalyst have a significant effect on ECODS efficiency of TBAPW₁₁Zn@TiO₂@PAni nanocomposite.     

Mesoporous zirconium–silica nanocomposite modified with heteropoly tungstophosphoric acid catalyst for ultra-deep oxidative desulfurization

An adsorbent catalyst was proposed to reduce the leaching of active species of the catalyst and enhance the kinetics of the oxidative desulfurization (ODS) reaction of dibenzothiophene (DBT) from model diesel fuel. By loading phosphotungstic acid (HPW) species onto a zirconium-modified hexagonal mesoporous silica (Zr-HMS), a novel catalyst was synthesized and utilized for the ODS process. An ultrafast ODS kinetics was specifically identified using 20%HPW/Zr-HMS as catalyst. Within 30 min, more than 95% of the 350 ppm DBT content of the model fuel was oxidized by H₂O₂. The synthesized catalyst retained its sulfur removal ability even after five subsequent ODS reactions and the leaching of HPW species was found to be suppressed successfully. Overall, this new reusable catalyst provided an alternative for highly efficient ultra-deep desulfurization process.     

Promotion of oxidative desulfurization performance of model fuel by 3DOM Ce-doped HPW/TiO2 material

Phosphotungstic acid (HPW) supported on Ce-doped three-dimensional ordered macroporous (3DOM) TiO₂ catalysts are studied in catalytic oxidation desulfurization (ODS) of model oil. The structural and textural of as-synthesized catalysts are characterized by N₂ adsorption, XRD, Raman spectroscopy, SEM-EDS, TEM, FT-IR, XPS, UV–Vis and ICP. These results upheld the existence of periodically arranged macroporous structure of catalyst, with Keggin-type of HPW dispersed homogeneously on TiO₂ matrix. Among these 3DOM Ce-doped HPW/TiO₂ materials, catalyst with 15 wt.% cerium dosage exhibits best ODS performance, which oxidized 99.8% of dibenzothiophene (DBT) into corresponding sulfone within 40 min. The excellent ODS performance of 3DOM Ce-doped HPW/TiO₂ catalyst is related to the common influence of more oxygen vacancies produced by electron transformation between Ce³⁺ and Ce⁴⁺. The chemisorbed oxygen on the surface catalyst will facilitate the selective oxidation of sulfides to sulfones. Moreover, the 3DOM structure of catalyst will further promote the mass transfer of reactants and products on the pore channel. The as-prepared catalyst shows excellent reusability in the ODS system, no obviously decrease in catalytic activity even after 6 runs.     

Ultradeep desulfurization of model oil through the oxidative adsorption process using Dawson‐type polyoxometalates and graphene oxide multifunctional composites

Eight Dawson‐type polyoxometalates were successfully prepared and used in an octanal/air oxidative desulfurization (ODS) system for model oil. Among which, the classical 2:18 polyoxometalate K₆[α‐P₂W₁₈O₆₂]·14H₂O exhibited the best catalytic performance with a sulfur removal ratio of 99.63%. Then, K₆[α‐P₂W₁₈O₆₂]·14H₂O was supported on graphene oxide (GO) to afford K₆P₂W₁₈O₆₂/GO using the hydrothermal method. Due to the in situ adsorption of the supported catalysts in the ODS process, the sulfur removal ratio was 96.10% without extraction treatment. Compared with the octanal/air ODS system using pure GO as an adsorbent for the oxidation products, the sulfur removal ratio increased from 89.21 to 96.10%, and the n‐octanal/S molar ratio decreased from 24 to 4. To facilitate the recycling of the catalyst and avoid catalyst loss, K₆[α‐P₂W₁₈O₆₂]·14H₂O was supported on magnetic graphene oxide (mGO) to afford K₆P₂W₁₈O₆₂/mGO. The results showed that the supported catalyst could be easily recovered with the aid of an external magnetic field, while maintaining high catalytic activity during five cycles of reuse with little catalyst loss. Furthermore, all the prepared materials were analyzed by a series of characterizations, and the reaction mechanism of the studied system was proposed through contrast tests and GC‐MS characterization analysis.     

银离子修饰的介孔磷钨酸/二氧化硅催化剂氧化脱硫性能研究

采用银修饰介孔磷钨酸/二氧化硅（mesoporous HPW/SiO₂）催化剂,并研究了其在模拟柴油和真实柴油氧化脱硫反应中的催化性能。通过银修饰介孔HPW/SiO₂,结合银离子对有机硫化物的选择吸附性和HPW对有机硫化物的催化氧化活性,以达到选择氧化脱硫的目的。模拟柴油分别采用石油醚、苯、1-辛烯和二苯并噻吩配制,当银离子与HPW的摩尔比为2时,催化剂具有最高的选择催化氧化活性。采用N₂ 吸附-脱附、XRD、UV-vis和EDS表征了银修饰的介孔HPW/SiO₂催化剂,结果表明,银物种分散均匀且以Ag⁺形式存在。真实柴油的脱硫研究表明,相比介孔HPW/SiO₂催化剂,修饰的催化剂介孔Ag₂-HPW/SiO₂脱硫率提高了4.6%,初始硫含量为1800×10^-6的直馏柴油能被脱除至228×10^-6,脱硫率为87.3%。介孔Ag₂-HPW/SiO₂催化剂具有良好的再生性能,经再生处理后,Ag的损失量极少,其三次脱硫率达到84.8%。     

Highly Efficient Extraction and Oxidative Desulfurization System Using Na7H2LaW10O36⋅32 H2O in [bmim]BF4 at Room Temperature

Highly efficient, deep desulfurization of model oil containing dibenzothiophene (DBT), benzothiophene (BT), or 4,6‐dimethyldibenzothiophene (4,6‐DMDBT) has been achieved under mild conditions by using an extraction and catalytic oxidative desulfurization system (ECODS) in which a lanthanide‐containing polyoxometalate Na₇H₂LnW₁₀O₃₆ ? 32 H₂O (LnW₁₀; Ln=Eu, La) acts as catalyst, [bmim]BF₄ (bmim=1‐butyl‐3‐methylimidazolium) as extractant, and H₂O₂ as oxidant. Sulfur removal follows the order DBT>4,6‐DMDBT>BT at 30 ° C. DBT can be completely oxidized to the corresponding sulfone in 25 min under mild conditions, and the LaW₁₀/[bmim]BF₄ system could be recycled for ten times with only slight decrease in activity. Thus, LaW₁₀ in [bmim]BF₄ is one of the most efficient systems for desulfurization using ionic liquids as extractant reported so far.     

Facile synthesis of inorganic–organic Fe2W18Fe4@NiO@CTS hybrid nanocatalyst induced efficient performance in oxidative desulfurization of real fuel

In this work, a new nanocatalyst, Fe₂W₁₈Fe₄@NiO@CTS, was synthesized by the reaction of sandwich‐type polyoxometalate (Fe₂W₁₈Fe₄), nickel oxide (NiO), and chitosan (CTS) via sol–gel method. The assembled nanocatalyst was systematically characterized by FT‐IR, UV–vis, XRD, SEM, and EDX analysis. The catalytic activity of Fe₂W₁₈Fe₄@NiO@CTS was tested on oxidative desulfurization (ODS) of real gasoline and model fuels. The experimental results revealed that the levels of sulfur content and mercaptan compounds of gasoline were lowered with 97% efficiency. Also, the Fe₂W₁₈Fe₄@NiO@CTS nanocatalyst demonstrated an outstanding catalytic performance for the oxidation of dibenzothiophene (DBT) in the model fuel. The major factors that influence the desulfurization efficiency and the kinetic study of the ODS reactions were fully detailed and discussed. The probable ODS pathway was proposed via the electrophilic mechanism on the basis of the electrophilic characteristic of the metal‐oxo‐peroxo intermediates. The prepared nanocatalyst could be reused for 5 successive runs without any appreciable loss in its catalytic activity. As a result, the current study suggested the potential application of the Fe₂W₁₈Fe₄@NiO@CTS hybrid nanocatalyst as an ideal candidate for removal of sulfur compounds from fuel.     

Membrane-Supported Layered Coordination Polymer as an Advanced Sustainable Catalyst for Desulfurization

The application of a catalytic membrane in the oxidative desulfurization of a multicomponent model diesel formed by most refractory sulfur compounds present in fuel is reported here for the first time. The catalytic membrane was prepared by the impregnation of the active lamellar [Gd(H₄nmp)(H₂O)₂]Cl·2H₂O (UAV-59) coordination polymer (CP) into a polymethyl methacrylate (PMMA, acrylic glass) supporting membrane. The use of the catalytic membrane in the liquid–liquid system instead of a powder catalyst arises as an enormous advantage associated with the facility of catalyst handling while avoiding catalyst mass loss. The optimization of various parameters allowed to achieve a near complete desulfurization after 3 h under sustainable conditions, i.e., using an aqueous H₂O₂ as oxidant and an ionic liquid as extraction solvent ([BMIM]PF₆, 1:0.5 ratio diesel:[BMIM]PF₆). The performance of the catalytic membrane and of the powdered UAV-59 catalyst was comparable, with the advantage that the former could be recycled successfully for a higher number of desulfurization cycles without the need of washing and drying procedures between reaction cycles, turning the catalytic membrane process more cost-efficient and suitable for future industrial application.     

Deep Desulfurization by Amphiphilic Lanthanide‐Containing Polyoxometalates in Ionic‐Liquid Emulsion Systems under Mild Conditions

Amphiphilic lanthanide‐containing polyoxometalates (POMs) were prepared by surfactant encapsulation. Investigation of these lanthanide‐containing POMs in oxidative desulfurization (ODS) showed that highly efficient deep desulfurization could be achieved in only 14 min with 100 % conversion of dibenzothiophene under mild conditions by using (DDA)₉LaW₁₀/[omim]PF₆ (DDA=dimethyldioctadecylammonium, omim=1‐octyl‐3‐methyl‐imidazolium) in the presence of H₂O₂. Furthermore, deep desulfurization proceeds smoothly in model oil with an S content as low as 50 ppm. A scaled‐up experiment in which the volume of model oil was increased from 5 to 1000 mL with S content of 1000 ppm indicated that about 99 % sulfur removal can be achieved in 40 mins in an ionic‐liquid emulsion system. To the best of our knowledge, the (DDA)₉LaW₁₀/[omim]PF₆ catalyst system with H₂O₂ as oxidant is one of the most efficient desulfurization systems reported so far.     

Deep Oxidative Desulfurization of Thiophenic Model Oil/Natural Gas Condensate Over Tungsten/Molybdenum Oxides Using H2O2 as Oxidant

Supported Na₂WO₄/ZSM5 as catalyst was used for deep oxidative desulfurization (ODS) of mixed thiophenic compounds model oil and natural gas condensate under mild conditions by using hydrogen peroxide as oxidant. A one factor at a time optimization strategy was applied for optimizing the parameters such as temperature, loading of catalysts, reaction time, type of extractant and oxidant to S‐compounds molar ratio. The corresponding products can be easily removed from the model by using MeCN as best extractant. Results showed highly catalytic activity of Na₂WO₄/ZSM5 for the oxidative removal of dibenzothiophene and mixed thiophenic model oil under atmospheric pressure at 75 °C in a biphasic system. By applying the ODS to mixed model/MeCN and gas condensate/MeCN, the conversion reached to 94 and 81 %, respectively, using 40 % loading Na₂WO₄/ZSM5 as catalysis under the optimal conditions. To investigate the oxidation and adsorption effects of gas condensate composition on ODS, effects of cyclohexene, 1,7‐octadiene, and o‐xylene were studied with different concentrations.     

乳液催化剂存在下空气辅助甲酸氧化法使油品脱硫(英文)

Catalytic oxidative desulfurization(ODS) of model oil and commercial oil samples was investigated using an air-assisted performic acid oxidation system with a phase transfer or emulsion catalyst comprising a quaternary ammonium salt-based heteropolyoxometalate.Different emulsion catalysts with a Keggin type heteroployoxometalate anion(containing W,Mo,and V) and cetyltrimethylammonium bromide cation were prepared and characterized by X-ray fluorescence,Fourier transform infrared spectroscopy,and scanning electron microscopy.[C16H33N(CH3)3]3[PW9Mo3O40] was the most effective catalyst in the current oxidation system,which reduced the sulfur content of the model oil from 1275 μg/g to 57 μg/g.The reactivity order of different model sulfur compounds was thiophene < dibenzothiophene < 4,6-dimethyldibenzothiophene. The ODS of model sulfur compounds followed first order kinetics with apparent activation energy from 29 to 27 kJ/mol.The catalysts also performed efficiently in the ODS of the industrial oil samples,including untreated naphtha,light gas oil,heavy gas oil,and Athabasca oil sands derived bitumen,for which sulfur removal rates were 83%,85%,68% and 64%,respectively.     

Hexacyanoferrate‐based ionic liquids as Fenton‐like catalysts for deep oxidative desulfurization of fuels

Two hexacyanoferrate‐based ionic liquids, [C₄Py]₃Fe(CN)₆ and [C₁₆Py]₃Fe(CN)₆, were synthesized and characterized using Fourier transform infrared and mass spectroscopies and CHN analysis. They were employed as Fenton‐like catalysts in extraction and catalytic oxidative desulfurization of model oil with dibenzothiophene (DBT), benzothiophene (BT), 4,6‐dimethyldibenzothiophene (4,6‐DMDBT), 4‐methyldibenzothiophene (4‐MDBT) and 3‐methylbenzothiophene (3‐MBT) as substrates. Various polar solvents, such as ionic liquids, water and organic solvents, were applied to choose a suitable extractant. The results showed the removal of DBT reached 97.1% with [C₄Py]₃Fe(CN)₆ as a catalyst and 1‐n‐octyl‐3‐methylimidazolium hexafluorophosphate ([C₈mim]PF₆) as an extractant under optimal conditions. The activity of sulfur removal followed the order DBT > 3‐MBT > BT > 4‐MDBT >4,6‐DMDBT. The effect of water content on sulfur removal was investigated by adding various concentrations of H₂O₂. It was found that excess water had a positive effect on sulfur removal but the catalysts were less sensitive than [FeCl₄^?]‐based catalysts to water. The mechanism was studied using electron spin‐resonance spectroscopy and gas chromatography–mass spectrometry. O₂^?? may be the active oxygen species in the catalytic oxidative desulfurization process and the oxidation products of various sulfur compounds were the corresponding sulfoxides and sulfones. Copyright © 2016 John Wiley & Sons, Ltd.     

Nd(OR)3-mClm-AlEt3 catalyst system in the polymerization of butadiene: I. The general feature of polymerization

Homopolymerization of butadiene has been carried out with a new series of binary catalyst system Nd(OR)_3-mG_m-AlEt₃. The catalytic activity as well as the microstructure of the resulting polymer have been studied. The results indicate that the stereospecificity of the polybutadiene obtained with these binary catalyst system (when m = 2) is similar to that prepared with ternary system Nd(OR)₃-Al₂Et₃Cl₃-AlEt₃, yet the catalytic activity of the former is somewhat higher. Thus possibly, the present simpler binary system is preferable to the ternary system when applied to the polymerization of butadiene.     

Large‐scale Two‐dimensional MoSx Catalyst Prepared under Mild Conditions for Enhancing Electrocatalytic Hydrogen Evolution Reaction

As an electrocatalyst with abundant resources and great potential, molybdenum disulfide is regarded as one of the most likely alternatives to expensive noble‐metals catalysts. However, it is still a challenge to achieve large scale production of few‐layer MoS₂ with enhancing activity of electrocatalytic hydrogen reaction at ambient conditions. Herein, we developed a simple environmentally friendly two‐step method, which included intercalation reaction and a subsequent electrochemical reduction reaction for mass preparation of defect‐rich desulfurized MoS_x (D?MoS_x) nanosheets with plentiful sulfur vacancies. The ratio of sulfur‐molybdenum atoms can be adjusted from 2 : 1 to 1.4 : 1 by regulating the desulfurization voltage. It was found that the HER catalytic activity of the D?MoS_x was enhanced compared with that of pristine MoS₂ (P?MoS₂), the current density of D?MoS_x (desulfurization at ?1.0 V) at ?0.3 V versus RHE was about 169% of the P?MoS₂, and the Tafel slope decreased to 136 mV dec^?1. This method can be widely applied to large‐scale preparation of other two‐dimensional materials.     

Oxidative desulfurization of model diesel oil over Ti-containing molecular sieves using hydrogen peroxide

Three Ti-containing molecular sieves were studied in the oxidative desulfurization (ODS) of model diesel oil with hydrogen peroxide. Under optimal conditions, dibenzothiophene (DBT) conversion up to 80.6% and 42.6% could be obtained with Ti-HMS and Ti-MSU as catalysts, respectively. However, there is no activity in the sulfoxidation of DBT over TS-1. Effects of the TiO₂/SiO₂ ratio in Ti-HMS and reaction conditions, such as the reaction temperature, reaction time, n(H₂O₂)/n(S) on the sulfur removal were investigated.     

Copper(II) Schiff Base Complex Immobilized on Superparamagnetic Fe3O4@SiO2 as a Magnetically Separable Nanocatalyst for Oxidation of Alkenes and Alcohols

A new heterogeneous catalyst containing a copper(II) Schiff base complex covalently immobilized on the surface of silica‐coated Fe₃O₄ nanoparticles (Fe₃O₄@SiO₂‐Schiff base‐Cu(II)) was synthesized. Characterization of this catalyst was performed using various techniques. The catalytic potential of the catalyst was investigated for the oxidation of various alkenes (styrene, α‐methylstyrene, cyclooctene, cyclohexene and norbornene) and alcohols (benzyl alcohol, 3‐methoxybenzyl alcohol, 3‐chlorobenzyl alcohol, benzhydrol and n ‐butanol) using tert ‐butyl hydroperoxide as oxidant. The catalytic investigations revealed that Fe₃O₄@SiO₂‐Schiff base‐Cu(II) was especially efficient for the oxidation of norbornene and benzyl alcohol. The results showed that norbornene epoxide and benzoic acid were obtained with 100 and 87% selectivity, respectively. Moreover, simple magnetic recovery from the reaction mixture and reuse for several times with no significant loss in catalytic activity were other advantages of this catalyst     

二苯并噻吩和吲哚在NiMoS/γ-Al2O3上加氢脱硫和加氢脱氮反应的相互影响

在固定床高压微反装置上考察了预硫化型NiMoS/γ-Al2O3催化剂上二苯并噻吩（DBT）加氢脱硫（HDS）反应和吲哚加氢脱氮（HDN）反应之间的相互影响。结果表明,吲哚对DBT的加氢脱硫反应具有抑制作用,其中对加氢路径（HYD）比对氢解路径（DDS）的抑制作用强,温度升高后,吲哚的抑制作用减弱。吲哚对DBT加氢脱硫反应的抑制作用源于吲哚及其HDN反应的中间产物在活性位上的竞争吸附。DBT和原位生成的H2S促进了催化剂表面硫阴离子空穴（CUS）向B酸位的转化,从而提高1,2-二氢吲哚（HIN）分子中C(sp3)—N键的断裂能力,使得吲哚的转化率和产物中邻乙基苯胺（OEA）的相对含量增大。HDN活性相的形成虽然需要硫原子的参与,但是活性相的保持并不需要大量的硫原子,较高含量硫化物存在时加氢活性位减少,不利于脱氮反应。