Oxidative desulfurization of dibenzothiophene based on molecular oxygen and iron phthalocyanine

Direct oxidation of dibenzothiophene (DBT) based on molecular oxygen and iron tetranitrophthalocyanine (FePc(NO₂)₄) catalyst was performed in hydrocarbon solvent under water-free condition for deep desulfurization. Conversion of DBT in decalin reached 98.7 wt.% at 100 °C and 0.3 MPa of initial pressure with 1 wt.% of FePc(NO₂)₄ over the whole solution for 2 h. In addition to FePc(NO₂)₄, another two catalysts, FePc(NO₂)₃NH₂ and FePc(NH₂)₄, were synthesized to investigate the effect of substituents of iron phthalocyanines on their catalytic activities. The results show that the catalytic activity of these phthalocyanines decreases in the order of FePc(NO₂)₄ > FePc(NO₂)₃NH₂ > FePc(NH₂)₄, indicating that the electron-donating group has negative effect on the catalytic properties. Activity of FePc(NO₂)₄ was kept unchanged after 5 runs of oxidation; whereas, activity of FePc(NH₂)₄ decreased because of its decomposition. Moreover, FePc(NO₂)₃NH₂ was supported on a polyacrylic cationic exchange resin and its activity was remarkably enhanced to the level of FePc(NO₂)₄. Oxidative desulfurization of a model fuel, 500 μg/g solution of DBT in decalin, was performed based on the catalytic oxidation using molecular oxygen and FePc(NO₂)₄ catalyst. The lowest sulfur content in the model fuel could be decreased to less than 4 μg/g after the treatment of this oxidation and a combined adsorption.     

Oxidative Desulfurization of Hydrocarbon Fuels

New requirements for very low sulfur content (10 ppm) in liquid motor fuels demand novel approaches for ultra-deep desulfurization. For production of near-zero-sulfur diesel and low-sulfur fuel oil, removal of refractory sulfur compounds, like 4,6-dimethyldibenzothiophene and other alkyl-substituted thiophene derivatives, is necessary. Elimination of these compounds by hydrodesulfurization (HDS) requires high hydrogen consumption, high pressure equipment, and new catalysts. Various oxidative desulfurization processes, including recent advances in this field for diesel fuels, and the drawbacks of this technology in comparison with HDS are examined and discussed. It is shown that the oxidation of sulfur compounds to sulfones with hydrogen peroxide allows for production of diesel fuels with a sulfur content of 10 ppmw or lower at atmospheric pressure and room temperature. The gas phase oxidative desulfurization of sulfur compounds with air or oxygen is feasible at atmospheric pressure and higher temperatures: 90–300 °С and offers better economic solutions and incentives.     

Oxidative desulfurization of Gas oil by polyoxometalates catalysts

Several polyoxometalates: Na₂HPM₁₂O₄₀, H₃PM₁₂O₄₀, Na₂HPM₁₂O₄₀, (VO)H[PM₁₂O₄₀] and (n-Bu₄N)₃[PM₁₂O₄₀] (M = Mo and W) as well as (n-Bu₄N)_3 + x[PW_12−xV_xO₄₀] (x = 0–3) were synthesized and characterized. Benzothiophene, dibenzothiophene and 4,6-dimethyl-dibenzothiophene were used as model sulfur compounds in gas oil. The oxidation reaction was performed using different polyoxometalates as catalyst and H₂O₂/acetic acid. The experimental results show that the W-based polyoxometalate catalysts are more active than the Mo catalysts. The oxidation reactivity of the catalysts depends on the type of countercation: Na⁺ > H⁺ > (VO)⁺ > (n-Bu₄N)⁺. In a series of (n-Bu₄N)_3 + x [PW_12−xV_xO₄₀] (x = 0–3) the order of catalytic activity is V₃ > V₂ > V₁ > V₀. The reactivity order of the sulfur compounds is: dibenzothiophene > 4,6-dimethyldibenzo-thiophene > benzothiophene. The catalytic system in this work was used for the oxidation of gas oil combined with solvent extraction to remove sulfur content in gas oil. Under mild reaction condition, high sulfur removal up to 98% can be achieved with high oil recovery (90%).     

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.     

轻质燃料油萃取/萃取精馏深度脱硫

为弥补加氢深度脱硫技术的不足,轻质燃料油的非加氢深度脱硫技术已成为目前的研究热点。本文介绍了萃取/萃取精馏深度脱硫技术的进展情况,包括技术优势,研究进展,工业应用,以及在应用中高效萃取剂的选取。     

空气氧化燃料油脱硫技术研究进展

空气氧化脱硫技术因其反应条件温和、不使用昂贵的氢气、投资和操作费用低等优点日益受到重视.目前研究的氧化脱硫技术大多采用H2O2作氧化剂,但H2O2存在价格昂贵、不能再生以及含硫废水排放等问题.采用廉价的空气作氧化剂的氧化脱硫技术可以克服H2O2作氧化剂存在的一些缺点,因此,受到广泛关注.介绍了空气在不同催化体系中氧化燃...     

Oxidative desulfurization of diesel fuel using amphiphilic quaternary ammonium phosphomolybdate catalysts

Phosphomolybdic acid (HPMo) modified respectively with tetramethyl ammonium chloride (TMAC), dodecyl trimethyl ammonium chloride (DTAC) and hexadecyl trimethyl ammonium chloride (HTAC) as the catalysts were prepared and characterized by FT-IR, XRD and SEM. The catalysts were evaluated for the oxidative desulfurization of benzothiophene (BT), dibenzothiophene (DBT) and straight-run diesel using hydrogen peroxide as an oxidant. Results show that all of the catalysts keep the Keggin structures and are finely dispersed with mixing of quaternary ammonium salts. Hexadecyl chains are more favorable to wrap up DBT to the catalytic center and form stable emulsion system with higher conversion rates of DBT. The shorter dodecyl chains can wrap up BT more suitably and bring smaller steric hindrance, which display higher conversion rates of BT. The oxidative reactions fit apparent first-order kinetics, and the apparent activation energies of DBT are much lower than those of BT. The desulfurization rate of straight-run diesel can be up to 84.4% with the recovery rate of 98.1% catalyzed by [HPMo][HTAC]₂ in 2 h. When increasing the extraction times, the desulfurization rates increase, but the recovery rates of diesel decrease significantly.     

柴油脱硫技术的研究进展

对目前清洁燃料油的生产技术进行了概述.随着世界清洁柴油中含硫标准的提高,降低柴油中硫含量已成为全球性关注的问题.近几年,出现了许多新的脱硫技术,其中柴油非加氢脱硫技术的研究进展较快.介绍了氧化脱硫和非氧化脱硫技术的理论基础,重点概述了这方面取得的最新成果,并从清洁生产的角度出发,对柴油脱琉技术的发展进行了辰望.     

Deep desulfurization of diesel via peroxide oxidation using phosphotungstic acid as phase transfer catalyst

High sulfur level in diesel fuel has been identified as a major contributor to air pollutant in term of sulfur dioxide (SO_x) through diesel fueled vehicles. The main aim of the present work is to develop a promising methodology for ultra deep desulfurization of diesel fuel using oxidation followed by phase transfer of oxidized sulfur. Experiments were carried out in a batch reactor using n-decane as the model diesel compound and also using commercial diesel feedstock. To remove sulfur tetraoctylammonium bromide, phosphotungstic acid, and hydrogen peroxide were used as phase transfer agent, catalyst and oxidant respectively. The percent sulfur removal increases with increasing the initial concentration of sulfur in fuel and with increasing the reaction temperature. Similar trends were observed when commercial diesel was used to carry out desulfurization studies. The amphiphilic catalyst serves as a catalyst and also as an emulsifying agent to stabilize the emulsion droplets. The effects of temperature, agitation speed, quantity of catalyst and the phase transfer agent were studied to estimate the optimal conditions for the reactions. The sulfur removal from a commercial diesel by phase transfer catalysis has been found effective and removal efficiency was more than 98%. Kinetic experiments carried out for the desulfurization revealed that the sulfur removal results are best fitted to a pseudo first order kinetics and the apparent activation energy of desulfurization was 30.6 kJ/mol.     

氧化法脱除重油催化裂化柴油中的硫化物

采用双氧水-甲酸对重油催化裂化柴油进行氧化,然后使用N,N-二甲基甲酰胺萃取剂萃取脱硫。研究了在反应体系中氧化时间、氧化温度以及双氧水与甲酸的加入量对氧化脱硫率的影响,并考察了加入分散剂Span-80的效果。最终得到双氧水-甲酸-Span-80体系最佳氧化条件：分散剂Span-80为2.0%,双氧水为36%,甲酸为32%,氧化温度为60 ℃,氧化时间为50 min。分散剂Span-80的加入可以大大提高双氧水-甲酸体系对重油催化裂化柴油的氧化脱硫能力。在双氧水-甲酸体系最佳条件下氧化萃取脱硫率为85.58%,双氧水-甲酸-Span-80体系脱硫率高达98.27%,重油催化裂化柴油的硫含量由12 500 mg/L降至216 mg/L。气相色谱结果显示,氧化脱硫后重油催化裂化柴油中的噻吩、苯并噻吩及其衍生物基本被脱除,有少量二苯并噻吩及其衍生物需要进一步脱除。     

柴油氧化吸附脱硫工艺的研究

以过氧化氢为氧化剂,甲酸为催化剂,Al2O3为吸附剂,研究柴油氧化吸附脱硫工艺条件。实验结果表明,在n（氧）∶n（硫）=10.0,氧化时间为40min,氧化温度为70℃,V（吸附剂）∶V（油）=1∶5.5,吸附时间为30min,吸附温度为40℃时,吸附柴油的脱硫率为97.32%,柴油w（硫）=20.5μg/g,达到欧洲Ⅳ柴油标准：w（总硫）〈50μg/g。     

Enhanced Oxidative Desulfurization of Dibenzothiophene by Functional Mo‐Containing Mesoporous Silica

Functional mesoporous Mo–SiO₂ materials were synthesized by a one‐pot and facile room‐temperature procedure, and characterized by X‐ray diffraction, TEM, Raman spectroscopy, FT‐IR, diffuse reflectance spectra, and BET analysis. The experimental results demonstrated that the mesoporous materials presented a high dispersion of molybdenum species and excellent catalytic activity for the removal of dibenzothiophene (DBT) without organic solvents as extractants. The catalytic performance on different sulfur‐containing compounds was also investigated in detail. After recycling for eight times, the removal of the oxidation desulfurization system could still reach high values. GC‐MS analysis detected the oxidation product of DBT. A mechanism was proposed for the absorptive oxidation process of sulfur compounds.     

Activity and stability of amino-functionalized SBA-15 immobilized 12-tungstophosphoric acid in the oxidative desulfurization of a diesel fuel model with H2O2

In this study, the stability and the catalytic activity of an ordered mesoporous SBA-15 immobilized 12-tungstophosphoric acid (H₃PW₁₂O₄₀, HPW) in the oxidative desulfurization (ODS) of benzothiophene (BT) and dibenzothiophene (DBT) were improved by a post-synthesis-grafting method. In this method, SBA-15 was functionalized to provide a large number of amine groups for the immobilization of HPW through electrostatic binding with (3-aminopropyl) triethoxysilane (APTES) using triflic acid as a protonated agent. The materials were characterized by X-ray diffraction (XRD), Fourier-transform infrared spectroscopy (FT-IR), N₂ adsorption–desorption, X-ray photoelectron spectroscopy (XPS), and transmission electron microscopy (TEM). The results show that the structure of functionalized SBA-15 support and the active phase of the HPW remained intact after immobilization. The synthesized PW^–H₃N⁺-SBA-15 catalyst showed a high catalytic activity for ODS, achieving BT and DBT conversion of 99.9% and 100% with the reaction conditions of reaction temperature of 50?°C, H₂O₂ dosage of 1?mL, catalyst dosage of 0.03?g, and reaction time 5 and 1?h, respectively. The catalyst also showed a high reusability after up to four cycles, for which the conversion of the fourth reaction was 90.0% for both BT and DBT.     

负载金属氧化物分子筛催化氧化模拟汽油的脱硫研究

A simulated gasoline consisting of model sulfur compounds of thiophene （C4H4S） and 3-methythiophene （3-MC4H4S） dissolved in n-heptane was tested for the oxidative desulfurization in the hydrogen peroxide （H202） and formic acid oxidative system over metal oxide-loaded molecular sieve. The effects of the oxidative system, loaded metal oxides, phase transfer catalyst, the addition of olefin and aromatics on sulfur removal were investigated in details. The results showed that the sulfur removal rate of simulated gasoline in the H202/formic acid system was higher than in other oxidative systems. The cerium oxide-loaded molecular sieve was found very active catalyst for oxidation of simulated gasoline in this system. The sulfur removal rates of C4H4S and 3-MC4H4S were enhanced when phase transfer catalyst （PTC） was added. However, the sulfur removal rate of simulated gasoline was reduced with the addition of olefin and aromatics.     

柴油脱硫技术与展望

随着世界清洁柴油中含硫标准的提高,降低柴油中硫含量已成为全球性关注的问题。近几年,出现了许多新的脱硫技术,其中柴油非加氢脱硫技术的研究进展较快。介绍了氧化脱硫和非氧化脱硫技术的理论基础,重点概述了这方面取得的最新成果,并从清洁生产的角度出发,对柴油脱硫技术的发展进行了展望。     

A new method for obtaining ultra-low sulfur diesel fuel via ultrasound assisted oxidative desulfurization☆

Due to the requirement of stringent rules for ultra-low sulfur content of diesel fuels, it is necessary to develop alternative methods for desulfurization of fossil fuel derived oil. Using appropriate oxidants and catalysts with the assistance of ultrasound irradiation, model compounds such as dibenzothiophene can be quantitatively oxidized in minutes. For diesel fuels containing various levels of sulfur content, and through the use of catalytic oxidation and ultrasonication followed by solvent extraction, removal efficiency of sulfur-bearing compounds can reach or exceed 99% in a short contact time at ambient temperature and atmospheric pressure. This simple approach can be the basis for obtaining ultra-low sulfur-containing diesel oil. GC-PFPD, GC-MS, and GC-SIMDIS were used to monitor the change of organic sulfur compounds and hydrocarbons in diesels during the process.     

Oxidation of sulfur components in diesel fuel using Fe-TAML catalysts and hydrogen peroxide

Dibenzothiophene-derivatives are catalytically oxidized to their corresponding sulfone product in homogeneous and two-liquid phase systems by H₂O₂ with an iron containing tetraamidomacrocyclic ligand (TAML) catalyst, Fe-TAML^®. The reaction medium is slightly caustic, pH 8, and uses t-BuOH as a co-solvent for solubilizing the dibenzothiophene starting compounds and their oxidation products. Fe-TAML^® catalyst concentrations are in the low micromolar range. H₂O₂ consumption is nearly stoichiometric (two-equivalents) in homogeneous conditions and only slightly less efficient under two-liquid phase conditions. The catalytic process when applied to a sample of commercial diesel fuel occurs under mild conditions with respect to temperature (50 °C), pressure (1 atm), and time (3 h), to remove greater than 75% of the total sulfur content of the fuel after secondary treatment with silica. Both alkyl-benzothiophenes and alkyl-dibenzothiophenes compounds in the diesel fuel were oxidized by the Fe-TAML^®/H₂O₂ system which facilitated their adsorption onto the silica. The mild reaction conditions result in no detectable over-oxidation of alkyl-dibenzothiophenes.     

多酸材料在燃油脱硫中的研究进展

多酸材料具备独特的酸性和氧化还原性能,在油品氧化脱硫领域得到广泛关注。本文综述了多酸材料在油品催化氧化脱硫领域的研究进展,详细叙述了多酸离子液体催化剂和以金属有机框架、氧化物、碳材料等为载体的负载型多酸催化剂的特点及其催化氧化燃油中多种有机硫化物的脱硫效果。将多酸与离子液体或其他载体结合后不仅能有效增强多酸的催化活性,而且可提高催化剂的热稳定性与重复利用性。本文对各类载体的特点及发展前景进行了详细比较,并对其研究现状进行了梳理。最后对多酸材料在氧化脱硫领域的发展方向提出了展望,指出了具有良好催化活性、循环性能及经济适用性强的多酸材料是未来的研究方向。     

油品氧化脱硫介孔催化剂研究进展

综述了介孔催化剂包括改性SBA-15介孔催化剂、改性MCM-n系列介孔催化剂、改性HMS介孔催化剂,介孔硅酸盐催化剂、介孔过渡金属氧化物催化剂及介孔碳催化剂在油品氧化脱硫中的应用。指出介孔催化剂能够高效催化转化油品中的大分子有机硫化物,通过负载钨、磷、钼、钛等元素使得油品氧化脱硫率大大增加,但是催化剂活性中心的稳定性和催化剂的寿命还需要进一步的提高。     

Microbial desulfurization of coal and oil

Biotreatment of fossil fuels may be regarded as suitable technology for the desulfurization of oil and coal before combustion, especially for small-scale combustion plants where flue gas cleaning is too expensive.

Although several patents, especially on the field of biodesulfurization of oil, already exist, successful application in a large scale could not be demonstrated until now. “Organic sulfur” is characterized by covalent C-S bonds and can be regarded as an element which is integrated in the macromolecular matrix of coal and in organic sulfur compounds present in oil. As for the results of more semi-empirical approaches no reproducibility and transferability to other oil qualities could be demonstrated when model compounds representing the organic sulfur species were used.

This research strategy resulted in a number of promising biochemical pathways for the degradation and/or desulfurization of such compounds. However, up to now the use of microorganisms able to degrade model compounds in a biotechnological process for coal or oil desulfurization does not meet the expectations.

Thus, it has to be concluded that additional research is needed which should be focussed on the development of biocatalysts with a broad substrate specificity and on methods to improve the availability of the organically bound sulfur in the molecular structure of oil and coal.