Removal of dibenzothiophene in diesel oil by oxidation over a promoted activated carbon catalyst

Oxidative removal of dibenzothiophene (DBT) in n-octane solution by H₂O₂ on a promoted activated carbon (AC) catalyst was studied. DBT adsorption and catalytic behaviors on AC were examined. Effects of pH in aqueous phase, amounts of AC and formic acid (HCOOH) for promotion as well as initial molar H₂O₂/S ratio were investigated. Experimental results led to conclusion that DBT was readily oxidized by H₂O₂ over an AC catalyst promoted by HCOOH. Suitable amount of AC can improve the activity of H₂O₂ resulting in a deeper extent of sulfur removal. A 100% conversion of DBT in an octane solution by H₂O₂ oxidation was attained on the HCOOH-H₂O₂/AC catalyst at 80°C for a reaction time of 30 min.     

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.     

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.     

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.     

Deep desulfurization of diesel by selective oxidation using amphiphilic paradodecatungstate catalyst

An amphiphilic paradodecatungstate catalyst, [(C₁₈H₃₇)₂N(CH₃)₂]₉[NaH₂W₁₂O₄₂] was prepared and characterized by Fourier transform infrared spectroscopy, UV–visible spectrum, differential thermal analysis, and thermogravimetric analysis. The amphiphilic catalyst exhibits very high catalytic activity that dibenzothiophene (DBT) in model diesel can be oxidized into dibenzothiophene sulfones using hydrogen peroxide as an oxidant. The reactivity of sulfur compounds decreased in the order of DBT > 4,6-DMDBT > BT > 5-MBT. The reaction rates of these sulfur compounds are sensitive to the electron density on sulfur atoms and the steric hindrance of the substituted groups of sulfur compounds. The sulfur level of a commercial diesel after desulfurization can drop from 200 ppm to about 12 ppm.     

Regulating sulfur removal efficiency of fuels by Lewis acidity of ionic liquids

It is urgent to develop a new deep desulfurization process of fuels as the environmental pollution increases seriously. In this work, a series of Lewis acidic ionic liquids (ILs) [C₄³MPy]Cl/nZnCl₂ (n=1, 1.5, 2, 3) were synthesized and used in extraction and catalytic oxidative desulfurization (ECOD) of the fuels. The effects of the Lewis acidity of ILs, the molar ratio of H₂O₂/sulfur, temperatures, and different substrates including dibenzothiophene (DBT), benzothiophene (BT) and thiophene (TS), on sulfur removal were investigated. The results indicated that [C₄³MPy]Cl/₃ZnCl₂ presented near 100% DBT removal of model oil under conditions of 323 K, H₂O₂/DBT molar ratio 6:1. Kinetics for the removal of DBT, BT and TS by the [C₄³MPy]Cl/₃ZnCl₂-H₂O₂ system at 323 K is first-order with the apparent rate constants of 1.1348, 0.2226 and 0.0609 h^-1, and the calculated apparent activation energies for DBT, BT and TS were 61.13, 60.66, and 68.14 kJ/mol from 298 to 308 K, respectively. After six cycles of the regenerated [CC₄³MPy]Cl/₃ZnCl₂, the sulfur removal had a slight decrease. [CC₄³MPy]Cl/₃ZnCl₂ showed a good desulfurization performance under optimal conditions.     

An organic‐inorganic heterogeneous catalyst based on Keplerate polyoxometalates for oxidation of dibenzothiophene derivatives with Hydrogen peroxide

An organic‐inorganic material (NH₄)₂(MimAM)₄₀[Mo₁₃₂O₃₇₂(CH₃COO)₃₀(H₂O)₇₂] have been synthesized by reacting [(NH₄)₄₂[Mo^VI₇₂ Mo^V₆₀O₃₇₂(CH₃COO)₃₀(H₂O)₇₂] with the ionic liquid 3‐Aminoethyl‐1‐methylimidazolium bromide. The catalyst showed remarkably a high catalytic performance in the oxidation of dibenzothiophene (DBT) derivatives with H₂O₂ 35% as a safe and green oxidant. The main parameters affecting the process including catalyst, acid additive, hydrogen peroxide amounts and temperature have been investigated in detail. Sulfur removal of DBT in n‐heptane reached to 98.3% yield at 40 °C using 2.5 mmol H₂O₂ and 100 mg of (NH₄)₂(MimAM)₄₀[Mo₁₃₂O₃₇₂(CH₃COO)₃₀(H₂O)₇₂] after 90 min. Under the optimal conditions, BT (benzothiophene), DBT (dibenzothiophene) and 4,6‐DMDBT (4,6‐dimethyl‐dibenzothiophene) achieved high desulfurization efficiency. Our results showed that the reactivity order of different model sulfur compounds are thiophene <4,6‐dimethyl dibenzothiophene< dibenzothiophene. The catalysts could be easily separated from the reaction solution by simple filtration and recycled for several times without loss of activity.     

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.     

Effective Heterogeneous Oxidative Desulfurization Catalyzed by H3PMo9W3O40@rht-MOF-1

With the increasingly strict standard for sulfur content in fuel, it is necessary to develop high-efficiency catalyst for extractive and catalytic oxidative desulfurization systems (ECODS). Herein, a series of three remarkable complexes H₃PMo_(12-n)W_nO₄₀@rht-MOF-1 ( 1 a , n=1; 2 a , n=2; 3 a , n=3) have been designed and prepared. Complexes 1 a , 2 a and 3 a were characterized by single-crystal X-ray diffraction and FT-IR, PXRD, SEM, N₂ adsorption-desorption isotherms, etc. Upon complex 3 a was applied as catalyst, it exhibited remarkably high catalytic activity in the ECODS reactions of aromatic sulfur compounds under optimal conditions. On the basis of its excellent heterogeneity, the catalyst could be recycled for nine consecutive cycles without significant losing of activity centers. Then, the reaction kinetics and mechanism were investigated and the activation energy have been calculated and discussed. Further, the complex 3 a is employed to catalyze the ODS of commercial diesel oil. As a result, the desulfurization efficiency reached 90%. These results provided important structure data for study the structure-property relationship and potential heterogeneous catalyst applied in ODS in industry.     

Catalytic Systems for the H<Subscript>2</Subscript>S Wet Oxidation at room Temperature

The catalytic wet oxidation process is the most attractive process for small-scale hydrogen sulfide (H₂S) removal from natural gas. The catalytic wet oxidation process is anticipated to be cost effective and simple so that it can be used for treating sour gases containing small amounts of H₂S and can be easily operated even in isolated sites. The development of effective catalyst is the key technology in the wet catalytic oxidation of H₂S. The scale of operation for the process has to be flexible so its use will not be limited by the flow rates of the gas to be treated. The heterogeneous catalytic wet oxidation of H₂S has been attempted on activated carbons, but the H₂S removal capacity still shows the low removal efficiency. The catalytic wet oxidation of H₂S was studied over Fe/MgO for an effective removal of H₂S. In order to develop a sulfur removal technology, one has to know what surface species of catalyst are the most active. This article discusses the following systematic studies: (i) the catalytic preparation to disperse Fe metal well on MgO support for enhancing H₂S removal capacity, (ii) the effect of the catalytic morphology on the activity of Fe/MgO for the H₂S wet oxidation, (iii) the influence of precursor and support on the activity of Fe/MgO for catalytic wet oxidation of H₂S to sulfur.     

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.     

Deep oxidative desulfurization of dibenzothiophene with molybdovanadophosphoric heteropolyacid-based catalysts

Three hydrophobic Keggin-type heteropolyacid catalysts, [C₃H₃N₂(CH₃)(C₂H₄)]₅PMo₁₀V₂O₄₀ ([C₂mim]PMoV), [C₃H₃N₂(CH₃)(C₄H₈)]₅PMo₁₀V₂O₄₀ ([C₄mim]PMoV) and [C₃H₃N₂(CH₃)(C₆H₁₂)]₅PMo₁₀V₂O₄₀ ([C₆mim]PMoV), were synthesized by reacting molybdovanadophosphoric acid with imidazolium bromides, and characterized by spectroscopic methods. Their use as catalysts in the extractive catalytic oxidative desulfurization process using hydrogen peroxide as the oxidant and acetonitrile as phase transfer agent was studied. The catalytic properties decreased in the order: [C₆mim]PMoV > [C₄mim]PMoV > [C₂mim]PMoV. The main factors influencing the rate of removal of dibenzothiophene (DBT) were investigated, including reaction temperature, the amounts of catalyst, H₂O₂ and acetonitrile. Nearly 100 % sulfur removal rate was achieved under optimal conditions. The catalyst could be recycled six times with only a slight decrease in activity. A reaction mechanism for DBT oxidation is proposed, in which the Keggin anions first obtain active oxygen from H₂O₂, then the DBT is oxidized to dibenzothiophene sulfones.     

Carbon-Supported Potassium Hydride for Efficient Low-Temperature Desulfurization

The industrial removal of organosulfur impurities from fossil fuels relies on transition-metal-based catalysts in harsh conditions (ca. 400 °C, up to 100 bar H₂), yet desulfurization (DS) of refractory alkyl dibenzothiophenes (DBTs) remains challenging. Here, we report that carbon-supported potassium hydride (KH/C) enables efficient DS of DBTs in mild conditions, viz. >97 % conversion of DBTs is achieved at 165 °C in 3–6 h while the yields of respective biphenyls are 84–95 % by using only 15 % excess of KH per a C−S bond. In addition, KH/C allows to lower the concentration of 4,6-Me₂DBT in the mesitylene solution from 1000 ppm to <3 ppm (165 °C, 20 h) and provides deoxygenation, denitrogenation and catalytic aromatic hydrogenation reactions. DS of various sulfur heterocycles by using KH/C, a transition-metal-free material based on earth abundant elements, is viable at low temperature and has prospects for the further development towards decentralized removal of organosulfur species from fossil fuels.     

功能化含磷钼酸介孔硅材料的制备及其在深度氧化脱硫中的应用

随着全球工业的快速发展,化石燃料的消耗量日益增加,从而导致有毒污染物的排放量随之增加.燃料油中的含硫化合物燃烧后会形成SOx.SOx排放到大气中会形成酸雨污染环境.因此,超清洁燃料的生产迫在眉睫.目前主要的脱硫工艺为加氢脱硫(HDS).HDS能够有效脱除燃油中的硫醚、硫醇和二硫化物等含硫化物,但对于芳香族硫化物及其衍生物(如苯并噻吩、二苯并噻吩和4,6-二甲基二苯并噻吩等)的脱除效果较差,而且HDS需要在高温、高压且有合适催化剂存在的条件下进行反应.因此,开发操作简单、反应条件温和、能够高效脱除芳香族硫化物及其衍生物的脱硫工艺已成为目前研究的热点.催化氧化脱硫(CODS)能够在温和条件下高选择性脱除芳香族硫化物及其衍生物,作为HDS的有效补充,在深度脱硫领域的应用得到了广泛认可.目前适用于CODS的催化剂有分子筛、甲酸、过氧化物酶、氧化钼和杂多酸等.其中,含钼(VI)催化剂在CODS中表现出良好的性能,得到了广泛的研究和应用.在CODS中,催化剂载体同样起着重要作用.从实际应用角度出发,无定形二氧化硅在制备过程及经济性方面存在着不可替代的优势.到目前为止,无定形SiO2负载磷钼酸(HPMo)作为CODS催化剂的研究鲜有报道.本课题组以聚乙烯吡咯烷酮(PVP)为介孔模板剂,以正硅酸四乙酯(TEOS)为硅源,通过沉淀法直接合成了功能化含HPMo介孔复合材料HPMo-SiO2.采用XRD,FT-IR,31P-NMR和XPS等测试手段对所制备的材料进行了表征.结果表明,作为催化活性位点的钼以磷钼酸的形式存在,磷钼酸的Keggen结构在负载过程中没有遭到破坏,并且活性磷钼酸能够均匀分散在二氧化硅载体上.HPMo-SiO2的比表面积为365.0 m2/g,总孔容为1.237 cm3/g,平均孔径为12.91 nm.本文系统研究了模型油脱硫反应条件、催化剂循环使用次数及催化反应动力学.结果表明,HPMo-SiO2具有高效的脱硫活性,在反应温度为55oC,催化剂与模型油质量比为0.7%,反应时间为10 min的条件下,二苯并噻吩(DBT)脱除率可达100%;在反应温度为60oC,催化剂与模型油质量比为1.0%,反应时间为30 min的条件下,苯并噻吩(BT)脱除率可达100%.同等反应条件下,DBT的反应活性大于BT.DBT及BT的氧化脱除反应均符合表观一级动力学模型,且DBT脱除反应的表观活化能小于BT脱除反应.所制备的催化剂经过10次循环使用,DBT脱除率仍可以达到95.2%(BT为95.7%),说明所制备的HPMo-SiO2催化剂具有高活性和强稳定性.通过气质联用及微库仑仪对反应产物进行了分析,结果表明,BT和DBT的氧化产物分别为苯并噻吩砜(BTO2)和二苯并噻吩砜(DBTO2),且氧化产物全部被催化剂吸附,油品中没有含硫化合物的存在,因此不需要后续的氧化产物分离操作,提高了整个脱硫工艺的经济性,并且有效减少了分离操作带来的油品损失.     

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.     

Ultra‐deep desulfurization of a model fuel using novel VOHPO4 0.5H2O/boehmite catalysts

A high‐surface‐area boehmite was used as the support for a series of vanadium phosphate catalysts. The catalysts were prepared by heating of V₂O₅ in an isobutyl alcohol and benzyl alcohol mixture at 140°C for 5 h to reduce V⁵⁺ to more active V⁴⁺ in the presence of phosphoric acid. Then a series of catalysts with various VPO loadings on boehmite were synthesized. The catalysts were characterized using various techniques. The catalysts were utilized for extraction combined with catalytic oxidation of dibenzothiophene. The important factors influencing the desulfurization process, including reaction time, temperature, H₂O₂, catalyst loading, catalyst amount and solvents, were systematically investigated. Under the optimized reaction conditions, i.e. 30 mg of catalyst loading at 50°C and in 60 min, sulfur removal reached 94%. The catalyst was recycled and reused five times.     

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.     

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。     

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 Na(7)H(2)LnW(10)O(36)?32?H(2)O (LnW(10); Ln = Eu, La) acts as catalyst, [bmim]BF(4) (bmim = 1-butyl-3-methylimidazolium) as extractant, and H(2)O(2) 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 LaW(10)/[bmim]BF(4) system could be recycled for ten times with only slight decrease in activity. Thus, LaW(10) in [bmim]BF(4) is one of the most efficient systems for desulfurization using ionic liquids as extractant reported so far.     

Effect of the nature of sulfur compounds on their reactivity in the oxidative desulfurization of hydrocarbon fuels with oxygen over a modified CuZnAlO catalyst

The reactivity of thiophene, dibenzothiophene (DBT), and 4,6-dimethyldibenzothiophene (4,6-DMDBT), which are the representatives of the main classes of sulfur compounds that are the constituents of diesel fractions, was studied in the course of their oxidative desulfurization with oxygen on a CuO/ZnO/Al₂O₃ catalyst modified with boron and molybdenum additives. At T ≥ 375°C, the reactivity increased in the order thiophene < DBT < 4,6-DMDBT. The degree of sulfur removal in the form of SO₂ from hydrocarbon fuel, which was simulated by a solution of 4,6-DMDBT in toluene, was 80%. Under the assumption of a first order reaction with respect to sulfur compound and oxygen, the apparent activation energies of the test processes were calculated. An attempt was made to reveal the role of the adsorption of sulfur compounds in the overall process of oxidative desulfurization with the use of X-ray diffraction analysis, X-ray photoelectron spectroscopy, and differential thermal and thermogravimetric analysis with the massspectrometric monitoring of gas phase composition.