Catalytic oxidative desulfurization of diesel utilizing hydrogen peroxide and functionalized-activated carbon in a biphasic diesel-acetonitrile system

This paper presents the development of granular functionalized-activated carbon as catalysts in the catalytic oxidative desulfurization (Cat-ODS) of commercial Malaysian diesel using hydrogen peroxide as oxidant. Granular functionalized-activated carbon was prepared from oil palm shell using phosphoric acid activation method and carbonized at 500 °C and 700 °C for 1 h. The activated carbons were characterized using various analytical techniques to study the chemistry underlying the preparation and calcination treatment. Nitrogen adsorption/desorption isotherms exhibited the characteristic of microporous structure with some contribution of mesopore property. The Fourier Transform Infrared Spectroscopy results showed that higher activation temperature leads to fewer surface functional groups due to thermal decomposition. Micrograph from Field Emission Scanning Electron Microscope showed that activation at 700 °C creates orderly and well developed pores. Furthermore, X-ray Diffraction patterns revealed that pyrolysis has converted crystalline cellulose structure of oil palm shell to amorphous carbon structure. The influence of the reaction temperature, the oxidation duration, the solvent, and the oxidant/sulfur molar ratio were examined. The rates of the catalytic oxidative desulfurization reaction were found to increase with the temperature, and H₂O₂/S molar ratio. Under the best operating condition for the catalytic oxidative desulfurization: temperature 50 °C, atmospheric pressure, 0.5 g activated carbon, 3 mol ratio of hydrogen peroxide to sulfur, 2 mol ratio of acetic acid to sulfur, 3 oxidation cycles with 1 h for each cycle using acetonitrile as extraction solvent, the sulfur content in diesel was reduced from 2189 ppm to 190 ppm with 91.3% of total sulfur removed.     

Fe/AC催化过氧化氢降解双酚A

传统Fenton反应存在对液相pH要求较高、Fe³⁺回收困难以及难以重复使用等问题。基于"活性离子固载化,酸性环境局部化"的设计思路,通过对活性炭(AC)表面酸化改性,制备得到载铁活性炭(Fe/AC)催化剂。研究了Fe/AC制备工艺与其性能之间的关系,结果表明,在载Fe³⁺量44.05 mg·g^-1、煅烧温度200℃的制备工艺下可得到催化活性较高、稳定性好的Fe/AC催化剂。用性能优良的Fe/AC催化H₂O₂降解双酚A(BPA),其较佳催化反应条件为:反应时间60 min、反应温度20℃、溶液pH值为4.0≤pH≤8.0、Fe³⁺/H₂O₂摩尔比为0.007～0.012、30% H₂O₂用量为0.04 ml H₂O₂·(mg BPA)^-1。本工作制备得到的Fe/AC催化剂具有较好的重复使用性能,在实际废水处理领域具有较大的应用前景。     

钨酸锰催化氧化脱除模拟油硫化物

通过直接沉淀法制备钨酸锰,采用高温煅烧和双氧水活化的钨酸锰为催化剂,过氧化氢为氧化剂,咪唑氟硼酸盐离子液体为萃取剂,氧化脱除模拟油中的二苯并噻吩(DBT)。研究了反应时间、反应温度、催化剂的加入量、氧化剂用量、萃取剂类型、硫化物类型等因素对催化氧化脱硫的影响,同时考察催化剂/萃取剂脱硫体系循环使用性能。结果表明,最优工艺条件为:反应温度为50℃,H2O2加入量为0.3 m L,催化剂为0.03 g,以咪唑氟硼酸盐为萃取剂,反应时间为60 min时,二苯并噻吩的脱除率可达90%。催化剂/离子液体回收重复使用5次,催化活性无明显下降。     

Fe2O3/AC催化剂上对甲基苯硫酚的水相催化氧化偶联

以对甲基苯硫酚为模型底物，空气为氧化剂，来研究硫醇水相催化氧化偶联制备二硫醚。以活性炭为载体，采用等体积浸渍法制备了一系列负载型氧化物催化剂，并考察了其在对甲基苯硫酚氧化偶联制备对甲苯二硫醚反应中的催化性能。反应结果表明，活性炭负载的铁氧化物具有最佳催化性能。采用N₂物理吸附、X射线衍射、X射线光电子能谱和透射电镜等表征手段对活性炭负载的铁氧化物催化剂进行了表征。表征结果表明，铁氧化物为高度分散在活性炭上的Fe₂O₃物种。以Fe₂O₃/AC为催化剂，当催化剂焙烧温度为400℃，Fe负载量为5%，在50℃下反应30min时，对甲苯二硫醚的收率高达97.4%；该催化剂循环使用5次后活性无明显下降。     

Recyclable HPW/PEHA/ZrSBA-15 toward efficient oxidative desulfurization of DBT with hydrogen peroxide

A layer-by-layer stabilization strategy was employed to immobilize active tungstophosphoric acid onto pentaethylenehexamine-preloaded acidic ZrSBA-15 with short pore channels. The composites were used as catalysts for the deep desulfurization of dibenzothiophene with hydrogen peroxide as green oxidant. The catalyst exhibited excellent desulfurization activity under optimum testing conditions. Moreover, it could be recovered and reused for six reaction runs without a discernible decrease in its activity.     

噻吩和苯并噻吩在原位氢存在下的还原脱硫

研究了噻吩和苯并噻吩在原位氢和硼化镍存在下的还原脱硫。实验对操作条件进行了优化;研究了可能的反应机理。结果表明,六水合氯化镍与还原剂于质子溶剂中反应的对硫化物脱硫,产生的原位氢脱硫活性较高;还原剂用量为0.64 g时,脱硫率可达99%以上。噻吩和苯并噻吩脱硫主要发生直接氢解反应;少量苯并噻吩脱硫经由加氢途径进行,硫化物主要通过S原子"端连吸附"在硼化镍表面。推测反应机理为,反应中大量原位氢吸附在硼化镍表面并活化;硼化镍中富电子镍介入硫化物分子中C—S键形成加合物,与活性原位氢进一步作用,使C—S和C—C键断裂。     

Fe2O3/AC催化剂的低温选择性催化还原脱硝性能

以活性焦(AC)为载体、Fe2O3为活性组分,采用等体积浸渍法制备Fe2O3/AC催化剂,研究了Fe含量对Fe2O3/AC催化剂低温脱硝性能的影响. 结果表明,当Fe负载量为6wt%时能获得比其它负载量更佳的NOx转化率,尤其在240℃时NOx转化率达93.9%,当分别有120?10?6(vol) SO2和3.5vol H2O存在时,脱硝率分别稳定在约86%和74%;催化剂孔径≤4 nm,随Fe负载量增加,孔径呈增大趋势;催化剂较稳定;Fe主要以γ-Fe2O3分散在催化剂表面,负载适量Fe2O3使表面吸附氧Oβ和Fe3+增多,为催化剂提供更多活性位,提高了Fe2O3/AC催化剂的低温选择性催化还原脱硝活性.     

Catalytic wet peroxide oxidation of phenol with a Fe/active carbon catalyst

A Fe on activated carbon catalyst has been prepared and tested for phenol oxidation with H₂O₂ in aqueous solution at low concentration (100 mg/L). Working at 50 °C, initial pH 3 and a dose of H₂O₂ corresponding to the stoichiometric amount (500 mg/L) complete removal of phenol and a high TOC reduction (around 85%) has been reached. Oxidation of phenol gives rise to highly toxic aromatic intermediates which finally disappear completely evolving to short-chain organic acids. Some of these last showed to be fairly resistant to oxidation being responsible for the residual TOC. In long-term continuous experiments the catalyst undergoes a significant loss of activity in a relatively short term (20–25 h) due to Fe leaching, this being related with the amount of oxalic acid produced. Deactivation may also be caused by active sites blockage due to polymeric deposits on whose formation some evidences were found. Washing with 1N NaOH solution allows to recover the activity although complete restoration was not achieved.     

Ce改性Fe2O3/AC催化剂低温SCR脱硝性能

以活性焦(AC)为载体、Fe和Ce为活性组分,采用等体积浸渍法制备了Fe2O3/AC和Ce?Fe2O3/AC催化剂,研究了Fe含量及Ce掺杂对Fe2O3/AC催化剂低温脱硝性能的影响,并对催化剂进行了表征. 结果表明,当Fe负载量为6wt%时,Fe2O3/AC催化剂的NOx转化率最高,240℃下达93.9%. 掺杂Ce后Ce?Fe2O3/AC催化剂的催化效率明显提高,当质量比Ce:Fe=0.5:6时,NOx转化率较高,120~200℃下NOx转化率比负载6wt% Fe的催化剂提高了5%?20%,且抗硫性能较好,240℃下通入100?10?6(vol) SO2,NOx转化率稳定在94.1%. 掺杂少量Ce可使γ-Fe2O3均匀分散在催化剂表面,且表面吸附氧Oα比例增大,催化剂的还原性增强,促进了选择性催化还原反应进行.     

Catalytic epoxidation with electrochemically in situ generated hydrogen peroxide

The epoxidation of allyl alcohol with in situ generated hydrogen peroxide was performed in an electrochemical cell with a trickle-bed electrode, composed of carbon black, graphite, PTFE and titanium silicalite-1 (TS-1) as heterogeneous epoxidation catalyst. Mass transport in interaction with the catalytic activity limits the epoxidation rate. The conversion of allyl alcohol increases with increase in the content of epoxidation catalyst in the electrode. In contrast, the specific reaction rate decreases due to the reduced accessibility of active sites in the catalyst.     

磷钨酸改性介孔材料HPW-HMS在汽油脱硫中的应用

以正十二胺为模板剂,正硅酸四乙酯为硅源,磷钨酸（HPW）为活性组分,采用一锅法制备了磷钨酸改性的介孔材料HPW-HMS.以30％双氧水为氧源,探索HPW-HMS催化剂对汽油氧化脱硫的效果.结果表明,当磷钨酸和正硅酸四乙酯摩尔比为0.02,催化剂质量0.2g,反应温度为55℃,反应12 h,双氧水2.5 mL时,脱硫效果达到68.3％,催化剂重复使用4次依然有良好的催化效果.     

Oxidative desulfurization of dibenzothiophene over Fe promoted Co–Mo/Al_2O_3 and Ni–Mo/Al_2O_3 catalysts using hydrogen peroxide and formic acid as oxidants

This work reports the enhancing effect of a highly cost effective and efficient metal, Fe, incorporation to Co or Ni based Mo/Al_2O_3 catalysts in the oxidative desulfurization(ODS) of dibenzothiophene(DBT) using H_2O_2 and formic acid as oxidants. The influence of operating parameters i.e. reaction time, catalyst dose, reaction temperature and oxidant amount on oxidation process was investigated. Results revealed that 99% DBT conversion was achieved at 60 °C and 150 min reaction time over Fe–Ni–Mo/Al_2O_3. Fe tremendously enhanced the ODS activity of Co or Ni based Mo/Al_2O_3 catalysts following the activity order: Fe–Ni–Mo/Al_2O_3 NFe–Co–Mo/Al_2O_3 NNi–Mo/Al_2O_3 NCo–Mo/Al_2O_3, while H_2O_2 exhibited higher oxidation activity than formic acid over all catalyst systems. Insight about the surface morphology and textural properties of fresh and spent catalysts were achieved using scanning electron microscopy(SEM), X-ray diffraction(XRD), energy dispersive X-ray(EDX)analysis, Atomic Absorption Spectroscopy(AAS) and BET surface area analysis, which helped in the interpretation of experimental data. The present study can be deemed as an effective approach on industrial level for ODS of fuel oils crediting to its high efficiency, low process/catalyst cost, safety and mild operating condition.     

Polyoxometalate-catalysed epoxidation of propylene with hydrogen peroxide: microemulsion versus biphasic process

Epoxidation of propylene with H₂O₂ catalysed by peroxo polytungstophosphates (P:W = 1:4), prepared by interaction of H₂WO₄, H₂O₂ and H₃PO₄ in the presence of Aliquat 336 as a surfactant, has been studied in chloride-free water-in-oil microemulsion (ME) Brij 30^® – n-octane – 30% aqueous H₂O₂ in comparison with the epoxidation in biphasic system 1,2-dichloroethane – H₂O. The epoxidation in ME occurs readily at 40–80 °C to give propylene oxide with 89–97% selectivity together with 3–11% propylene glycol. The catalyst can be reused but with a significant loss of activity. ³¹P NMR and chemical analysis indicate that the polyoxometalate catalyst is unstable in the ME system. In contrast, the epoxidation in the biphasic system occurs without catalyst decomposition, giving 83–86% epoxide and 14–17% glycol, and the catalyst can be easily reused without loss of activity and selectivity. The H₂O₂ utilisation in biphasic system (97–100%) has been found to be higher than in ME system (70–85%) at 60 °C.     

过氧化氢用于油品氧化脱硫的研究进展

氧化脱硫技术是一种很有发展前途的脱硫技术,过氧化氢是油品氧化脱硫技术中研究最普遍的氧化剂。综述了近年来国内外以过氧化氢为氧化剂的燃料油氧化脱硫技术的研究进展,介绍了在不同的催化剂如有机酸、杂多酸、分子筛、离子液体等作用下过氧化氢氧化脱硫的效果及其机理,同时对其应用前景进行了展望。     

甲基橙在Fe0-NaA-SSFSF固定床上的催化湿式H2O2氧化

通过二次生长法和液相还原法制备了不锈钢纤维烧结毡复合NaA分子筛膜-纳米零价铁复合材料(Fe0-NaA-SSFSF),研究了甲基橙在基于Fe0-NaA-SSFSF固定床上的催化湿式H2O2氧化性能,考察了不同pH值、床层高度、温度和入口浓度对甲基橙转化率、COD去除率和铁浸出浓度的影响,并测定了Fe0-NaA-SSFSF催化剂的稳定性。结果表明,当溶液pH为2.5时,甲基橙转化率在实验所测时间范围内有所波动;随pH降低至2.0,甲基橙转化率趋于稳定;继续降低pH至1.5,甲基橙转化率基本保持不变。随床层高度由0.45 cm增加至0.90 cm,甲基橙转化率基本保持不变,COD去除率由21.2%增加至85.0%;随温度由70℃降低至50℃,甲基橙转化率基本保持不变,COD去除率由85.0%降低至42.4%。随甲基橙入口浓度增加,甲基橙转化率和COD去除率变化幅度均很小。当pH=2.0、床层高度0.90 cm、温度70℃、甲基橙浓度50~200 mg/L条件下,实验所测时间范围内甲基橙转化率均大于97%,最大铁浸出浓度低于10.2 mg/L,固定床连续运转240 min后COD去除率均大于85%。催化剂被重复使用三次后,甲基橙转化率基本保持不变。     

Initiation of lipid peroxidation by a peroxidase/hydrogen peroxide/halide system

A lactoperoxidase/H₂O₂/halide system caused the initiation of linoleate peroxidation as indicated by diene conjugation. Coupled lipid peroxidation was accelerated by iodide, chloride and bromide ions at pH 4.0 and 6.2. No peroxidation occurred in the presence of H₂O₂ or lactoperoxidase alone. The rate of linoleate peroxidation by lactoperoxidase in the presence of chloride depended on the concentration of H₂O₂. Linoleate peroxidation by the enzymatic system was inhibited by high concentration of H₂O₂ by methionine, tryptophan and BHT. Oxygen was absorbed during peroxidation and the major products were the 13-hydroperoxides. The mechanisms of the initiation of lipid peroxidation by a peroxidase/H₂O₂/halide system are discussed.     

Catalytic performance of P-modified MoO3/SiO2 in oxidative desulfurization by cumene hydroperoxide

Phosphorous-modified MoO₃/SiO₂ catalysts with various P/Mo molar ratios (MoP_xO/SiO₂, x = 0.3 − 3.0) were prepared by co-impregnation and compared with MoO₃/SiO₂ in the oxidation of dibenzothiophene by cumene hydroperoxide. The addition of P significantly enhanced the catalytic performance, and MoP_1.0O/SiO₂ exhibited the highest oxidation activity. XRD characterization indicated that the active phase of MoP_1.0O/SiO₂ was amorphous, whereas ³¹P-NMR measurements revealed that MoP_1.0O/SiO₂ had a similar connectivity of Mo-O-P to H₃PMo₁₂O₄₀. The total sulfur of a hydrotreated diesel was reduced from 298 to 5 ppmw by oxidation with CHP and subsequent dimethylformamide extraction.     

Enhanced oxidative desulfurization of model fuels using a film-shear reactor

A film-shear reactor was used to enhance the oxidative desulfurization of thiophenes in fuels. With selected conditions, one pass of a model fuel through the film-shear reactor provided up to 55% removal of benzothiophene in only seconds at temperatures as low as 10 °C. Recirculation experiments showed that, if the flow rate and all other experimental parameters were held constant, the extent of thiophene removal increased as the residence time increased. Experiments using various concentrations of hydrogen peroxide and different fuel:oxidant ratios showed that, above a minimum amount, an increase in oxidant concentration did not lead to increased thiophene removal.     

Catalytic oxidation of hydrogen over Au/TiO2 catalysts

Selective catalytic oxidation of hydrogen in the presence of hydrocarbons was studied in a fixed bed quartz reactor, over 3 wt%Au/TiO₂ and 5 wt%Au/TiO₂ catalysts. This reaction can be utilised in the production of light alkenes via catalytic dehydrogenation, providing in situ heat to the endothermic dehydrogenation reaction and simultaneously removing a fraction of the produced hydrogen. It is important to avoid the non-selective combustion of the hydrocarbons in the mixture. Both 3 wt%Au/TiO₂ and 5 wt%Au/TiO₂ are active for the combustion of hydrogen, but in a gas mixture with propane and oxygen the selectivity is dependent upon the feed ratio of hydrogen and oxygen. At 550 °C, with propane present, no carbon oxides are formed when the H₂:O₂ ratio is four, but at lower ratios some CO₂ and some CO is formed.     

W改性SiO2催化剂催化氧化脱除苯并噻吩的性能

采用溶胶-凝胶法制备了W改性SiO2催化剂,并通过X射线衍射(XRD)、红外光谱(FTIR)、N2吸附(BET)、扫描电镜(SEM)等方法对催化剂进行表征。以苯并噻吩(BT)/石油醚模拟油为原料、H2O2为氧化剂,研究了催化剂催化氧化脱硫性能,考察了溶剂及用量、反应温度、氧化剂用量、催化剂用量、反应时间对苯并噻吩脱硫率的影响。结果表明,催化剂中W以WO3晶相存在,引入W后催化剂的比表面积有所降低。在模拟油原料20 mL、催化剂用量0.04 g、H2O2/S摩尔比8、乙腈/模拟油体积比0.3∶1、65℃下反应60 min时,模拟油脱硫率可达99.6%。