离子液体耦合有机过氧化物脱除二苯并噻吩的研究

以12-磷钨酸为催化剂,研究了离子液体耦合有机过氧化物脱除二苯并噻吩(DBT)。研究结果表明,单独使用离子[bmim]BF4、[bmim]PF6液体为萃取剂,脱硫率为27.78%~38.76%。以由等体积的H2O2与甲酸制成有机过氧化物为氧化剂,不使用催化剂和离子液体,温度70℃,反应时间6 h,DBT氧化为二苯并噻吩砜的比例为76.6%。在催化剂作用下,将离子液体与氧化剂耦合使用时,脱硫率明显提高。当催化剂与DBT的摩尔比为0.20∶1,氧化剂与DBT的体积比为10∶1,[bmim]PF6离子液体与DBT的体积比为1∶1,在70℃反应6 h后,脱硫率可达98.60%。耦合体系重复使用五次后,氧化脱硫活性没有明显降低。     

吡啶类离子液体萃取-氧化脱除含硫化合物

制备了N-丁基吡啶四氟硼酸盐离子液体([BPy]BF₄), 考察了其对含有噻吩和二苯并噻吩的模型油萃取脱硫的效果. 在此基础上以离子液体为萃取剂, 以过氧化氢(质量分数30%)为氧化剂, 研究了其对模型油进行萃取-氧化脱硫的效果, 结果表明, 当V([BPy]BF₄)∶V(Oil)∶V(H₂O₂)=1∶1∶0.4时, 在55 ℃下进行萃取-氧化脱硫30 min, 噻吩和二苯并噻吩的脱硫率分别达到78.5%和84.3%; 将该萃取-氧化体系应用于实际汽油体系, 脱硫率达到56.3%; 对使用过的离子液体进行再生处理, 重复使用4次脱硫率无明显变化.     

酸性离子液体催化的羟基化合物对N-对甲苯磺酰基氮杂环丙烷的开环反应

本文研究了羟基化合物对两种类型N-对甲苯磺酰基氮杂环丙烷的开环反应。在功能性离子液体[hmim]HSO4存在条件下,氮杂环丙烷与醇反应,以中等到高的产率和非常高的区域选择性得到对应的β-胺基醚。并且离子液体[hmim]HSO4可以循环使用。     

酸性离子液体萃取/催化二苯并噻吩氧化脱硫反应的优化

ö以Brönsted酸性离子液体N-甲基-2-吡咯烷酮磷酸二氢盐(\[Hnmp\]H₂PO₄)为萃取剂和催化剂,双氧水为氧化剂,二苯并噻吩(DBT)溶于正辛烷为模型油,利用正交实验法优化了DBT氧化脱硫反应工艺。所优化的反应条件为：反应温度60℃,模型油与离子液体体积比为1∶1,氧/硫摩尔比为16, 氧化时间5h;在此条件下模型油脱硫率达99.8%,实际柴油脱硫率为64.3%。由正交实验极差可知,各因素对DBT脱硫率影响的大小依次为：反应温度＞反应时间＞氧/硫摩尔比＞剂油比;离子液体循环利用6次,脱硫率下降不明显。     

KNO3体系中离子液体辅助水煤浆电解脱硫

在稳流条件下,考察了KNO₃体系中离子液体辅助煤浆电解脱硫效果.研究了煤浆电解过程中离子液体结构、浓度、温度和时间对脱硫率的影响.当咪唑类离子液体有机结构相同时,不同阴离子脱硫率由高到低顺序为:Br^- >BF₄^- >Cl^-;当阴离子同为Br^-时,咪唑脱硫效果优于吡啶.随着吡啶类离子液体([BPy]Br)浓度增加,脱硫率先增加,在0.3 mol/L处达到最大值,而后下降.此外,脱硫率随温度和时间增加而增大.最后,通过X射线光电子能谱(XPS)分析技术对实验前后煤中有机硫形态进行了分析.结果表明,噻吩主要通过萃取-氧化反应脱除,而其他形式有机硫(如硫醚、亚砜)则主要通过促进氧化及水解反应脱除.     

氨基酸基咪唑离子液体氧化萃取脱硫研究

通过离子交换法制备以天冬氨酸(Asp)、组氨酸(His)、甘氨酸(Gly)、色氨酸(Try)为阴离子的氨基酸咪唑离子液体,与H_2O_2协同深度去除模拟汽油中的二苯并噻吩(DBT)。对合成的氨基酸咪唑离子液体进行了FT-IR、1H NMR表征,并优化氧化脱硫工艺条件。结果表明,与以组氨酸、甘氨酸和色氨酸作为离子液体的阴离子相比,天冬氨酸作为阴离子时,离子液体与H_2O_2体系的催化萃取脱硫效果最好。通过对反应温度、H_2O_2/模拟油体积比和反应时间的工艺优化,探讨了[C_8mim]Asp和H_2O_2催化萃取脱硫的效果,最优工艺条件下,脱硫率可达96.5%。[C_8mim]Asp离子液体再生循环7次后脱硫率仍能保持在93.7%。对[C_8mim]Asp和H_2O_2协同催化脱硫机理的研究发现,[C_8mim]Asp的羧基与双氧水反应成过氧化羧基,将二苯并噻吩氧化成为二苯并噻吩砜,从而达到脱硫的目的。     

酸性离子液体萃取-氧化模拟油品脱硫研究

以酸性离子液体N-羧甲基吡啶硫酸氢盐(\[CH₂COOHPy\]HSO₄)为萃取剂和催化剂,过氧化氢为氧化剂,用于模拟油品(二苯并噻吩溶于正辛烷配制而成)萃取-氧化脱硫反应,考察过氧化氢用量、离子液体用量、反应温度和反应时间对脱硫率的影响。研究结果表明,当氧硫摩尔比(H₂O₂/S)为6,在10mL模拟油品中加入0.6mL离子液体, 50℃下反应40min,脱硫率可达99.7%。离子液体循环再生使用5次,脱硫率没有明显下降。     

羧基功能化苯并三氮唑类离子液体的合成及在萃取-氧化脱硫中的应用

合成了新型离子液体(ILs)1-烷基-3-羧甲基苯并三氮唑双三氟甲磺酰亚胺盐,并对其进行了表征.将其与双氧水组成催化氧化体系,考察了脱除模型油品中硫化物的效果.结果表明,以离子液体1-5基-3-羧甲基苯并三氮唑双三氟甲磺酰亚胺盐[C2O2BBTA][NTf2]为萃取/催化剂,设定n(H2O2)∶n(S)=2.5∶1,m(模型油)∶m(离子液体)=5∶1,在75℃下反应1 h后,模型油中二苯并噻吩(DBT)、苯并噻吩(BT)和4,6-二甲基二苯并噻吩(4,6-DMDBT)的脱硫率分别为98.3%,98.3%和96.6%.所合成离子液体重复使用10次,脱硫率无明显变化.该方法操作简单、反应条件温和,可以实现深度脱硫.     

酸性离子液体催化合成1,5-苯并二氮衍生物

以邻苯二胺和酮为原料,酸性离子液体[hmim]HSO4和乙醇为催化体系,合成了一系列1,5-苯并二氮衍生物,其结构经1^H NMR,IR和元素分析表征。催化体系可循环使用3次。     

有机-无机杂多酸类离子液体催化汽油超声氧化脱硫

合成了一系列有机-无机杂多酸类离子液体, 并将其应用于超声作用下的催化模拟汽油氧化脱硫反应. 结果表明, 在超声波辅助下, 不仅反应时间大大缩短, 而且脱硫效率也大幅提高. 在合成的一系列催化剂中, Zr_0.25[BMIM]HPW₁₂O₄₀表现出最佳的催化活性. 考察了超声波功率、 超声/间隙时间、 催化剂用量、 H₂O₂用量、 反应温度及反应时间等因素对脱硫效果的影响. 以Zr_0.25[BMIM]HPW₁₂O₄₀为催化剂, 在优化的条件下[n(Cat.)=0.008 mmol, V(H₂O₂)=40 μL, V(模拟油)=10 mL, V(乙腈)=1 mL, 温度25 ℃, 时间10 min, 超声功率300 W, 超声时间2 s, 间隙时间1.5 s], 二苯并噻吩(DBT)的脱硫率达到97.8%; 该催化剂循环使用5次后, 脱硫率仍为81.9%; 其对不同硫化物的催化活性顺序为DBT>4,6-二甲基苯并噻吩(4,6-DMDBT)>乙硫醚>苯硫醚>正丁硫醇>甲基苯基硫醚>苯并噻吩(BT)>噻吩.     

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 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.     

N-butyl-pyridinium tetrafluoroborate as a highly efficient ionic liquid for removal of dibenzothiophene from organic solutions

In this research,1-butyl-pyridinium tetrafluoroborate([C4Py][BF4]-)was prepared by ion exchange method and was characterized by1H-NM R,13C-NM R,and FT-IR techniques.The synthesized ionic liquid w as used for removal of dibenzothiophene as a typical organosulfur pollutant from organic medium.The effect of different parameters on the extraction efficiency w as studied and optimized.At the optimized conditions,97.68%of dibenzothiophene w as extracted from 1 000 mg/L n-hexane solution.The extraction efficiency obtained in this w ork w as higher than the previous reported values.The desulfurization reaction w as kinetically follow ed the second order mechanism.The ionic liquid w as reusable and after four regeneration cycles 97%of its original extraction efficiency w as retained.     

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.     

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.     

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.     

Molybdenum (VI)‐functionalized UiO‐66 provides an efficient heterogeneous nanocatalyst in oxidation reactions

A novel heterogeneous nanocatalyst was established by supporting molybdenum (VI) on Zr₆ nodes in the structure of the well‐known UiO‐66 metal–organic framework (MOF). The structure of the UiO‐66 before and after Mo (VI) immobilization was confirmed with XRD, DR‐FTIR and UV–vis spectroscopy, and the presence and amount of Mo (VI) was identified by X‐ray photoelectron spectroscopy and inductively coupled plasma atomic emission spectroscopy. TEM imaging confirmed the absence of Mo clusters on the MOF surface, while SEM confirmed that the appearance of the MOF has not changed upon immobilizing the Mo (VI) catalyst. BET adsorption measurements were used to confirm the porosity of the catalyst. The catalytic activity of this heterogeneous catalyst was investigated in oxidation of sulfides with H₂O₂ in acetonitrile and oxidative desulfurization of dibenzothiophene. Easy work up, convenient and steady reuse and high activity and selectivity are prominent properties of this new hybrid material.     

Efficient and sustainable V-catalyzed oxidative desulfurization of fuels assisted by ionic liquids

Fuel desulfurization is an appealing topic for the chemical industry since severe environmental regulations regarding SO₂ emissions have been legislated in many countries. In order to reduce the amount of sulfur-containing compounds in fuels, responsible for high SO_x emission levels, a green chemistry approach is compulsory. In this paper, vanadium salen and salophen complexes were used in the oxidation of a model aromatic sulfide, such as dibenzothiophene (DBT), in the presence of H₂O₂ as green oxidant. The oxidative process was successfully coupled with the extraction of the oxidized compounds by ionic liquids. The system resulted highly selective for sulfide oxidation, showing poor reactivity toward the oxidation of alkenes and allowing a significant reduction of S content in a model benzine. To note, the use of microwave in place of standard heating allowed to obtain 98% of DBT oxidation and almost complete sulfur extraction in the model fuel in 1000 s. For these reasons, this system was considered an easy, rapid and clean process to achieve fuel desulfurization.     

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.     

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.