Deep oxidative desulfurization of model fuel using ozone generated by dielectric barrier discharge plasma combined with ionic liquid extraction

The dielectric barrier discharge (DBD) is often used to prepare ozone. In this study, a novel room temperature oxidative desulfurization method involving ozone oxidation produced in the DBD reactor combined with ionic liquid (IL) [BMIM]CH₃COO ([BMIM]Ac) extraction was developed. The method was suitable for the deep removal of sulfur (S)-containing compounds from model fuel. By this desulfurization technology, 4,6-dimethyldibenzothiophene (4,6-DMDBT), dibenzothiophene (DBT), benzothiophene (BT) and thiophene (TS) were efficiently removed. Normally, the removal of TS and BT from fuel is highly difficult. However, using the proposed method of this study without any catalyst, the removal rate of TS and BT reached 99.9%. When TiO₂/MCM-41 was used as a catalyst, the S-removal of DBT and 4,6-DMDBT increased to 98.6 and 95.2%, respectively. The sulfur removal activity of the four sulfur compounds decreased in the order of TS > BT >> DBT > 4,6-DMDBT.     

Deep oxidative–extractive desulfurization of fuels using benzyl‐based ionic liquid

Four benzyl‐based ionic liquids (ILs) were synthetized and used for deep desulfurization of model oil and real diesel fuel. The removal efficiencies of benzothiophene (BT) and dibenzothiophene (DBT) with [Bzmim][NTf₂] and [Bzmim][SCN] as extractants are higher than that with [Bzmp][NTf₂] and [Bzmp][SCN] as extractants. The desulfurization capability follows the Nernst's Law. A reactive extraction mathematical model for desulfurization was established. An oxidative‐extractive two‐step deep desulfurization method was developed. DBT was first oxidized by H₂O₂ with CH₃COOH as catalyst and then the unoxidized DBT and uncrystallized dibenzothiophene sulfoxide (DBTO₂) in model oil were extracted by [Bzmim][NTf₂], and finally the removal efficiency was 98.4% after one‐stage extraction. Besides, the removal efficiency of 4,6‐DMDBT was 96.4% after oxidation and one‐stage extraction processes. Moreover, the oxidative‐extractive two‐step deep desulfurization method was also effective for desulfurization of diesel fuel. The removal efficiency of sulfur reached up to 96% after oxidation and three‐stage cross‐current extraction processes. © 2016 American Institute of Chemical Engineers AIChE J, 62: 4023–4034, 2016     

氧化吸附法脱除燃油中苯并噻吩类硫化物

为深度脱除燃油中苯并噻吩类硫化物,采用质量分数69.8%浓硝酸作为催化剂和氧化剂,负载于硅胶吸附剂孔中制备成脱硫剂,在间歇反应器中,常温常压操作条件下处理质量分数1 000×10-6 4,6-二甲基二苯并噻吩(4,6-DMDBT)模型油.结果显示:脱硫剂在温度45 ℃,吸附剂与催化剂负载质量比1: 0.75,吸附剂与燃...     

Trihexyl(tetradecyl)phosphonium hexafluorophosphate as an promising Extractant for extractive desulfurization from liquid fuels

Experimental data on extractive desulfurization (EDS) of dibenzothiophene (DBT), thiophene, benzothiophene, and other substituted derivatives of sulfur from liquid fuel using trihexyl(tetradecyl)phosphonium hexafluorophosphate ([THTDP][PF₆]) have been presented. The Fourier transform infrared spectrophotometer, ¹H-NMR, ¹³C-NMR, and ³¹P-NMR analysis have been discussed for molecular confirmation, and conductivity, solubility, and viscosity analyses of ([THTDP][PF₆]) were investigated. The effects of time, temperature, S-compounds, ultrasonication, and recycling of ([THTDP][PF₆]) on DBT removal from fuel were examined. Also, desulfurization of real fuels and multistage extraction was also tested. The data and results provided the significant insights of phosphonium ionic liquids as a promising solvent for EDS.     

用离子液体脱除燃料油中有机硫化物的研究

以咪唑类离子液体作为萃取脱硫剂,在正辛烷和甲苯的混合溶液中加入少量的噻吩构成油品模拟体系。采用正交实验,系统考察了单级萃取中温度、时间、剂油比以及离子液体碳数对脱硫效率的影响,得到了较优的脱硫条件:温度约60℃、萃取时间约40 min、剂油比为1∶1、侧链碳数为10。考察了多级脱硫效率以及离子液体的回收利用。结果表明,经过5级脱硫后,燃料油含硫可以达到欧Ⅲ标准,离子液体重复使用5次后,脱硫效率约降低了2%。回归得到了模拟油品中脱除噻吩的萃取动力学方程。该研究为基于离子液体的燃料油脱硫工艺提供了重要的基础。     

模仿离子液银盐法进行脱硫工艺的研究

油品中含硫化合物所产生的危害是多方面的,特别是近年来车用燃料尾气排放的二氧化硫对环境造成的负面影响更引起了人们的关注。发达国家纷纷制定环保法规严格限制油品中硫的质量分数,因此,讨论各种脱硫技术对我国炼油工业具有重要意义。对一种新的脱硫方法进行了考察。将235～270℃之间的煤油馏份进行预先精制,向其中加入一定量的苯并噻吩、二苯并噻吩作为原料,在氮气保护条件下进行烷基化脱硫工艺的研究。实验结果表明：在反应温度为30℃,CH3CH2Br：S=30：1（mol／mol）,AgBF4：S=6：1（mol／mol）,反应时间为16h的条件下,脱硫率可以达到76．3％。     

[Cnmim]Br/FeCl3型离子液体萃取脱除二苯并噻吩

合成了6种咪唑型离子液体[C_3-8mim]Br/FeCl₃,采用红外光谱和拉曼光谱对其进行表征,并考察了离子液体对二苯并噻吩的萃取脱除效果。结果发现,[C₃mim]Br/FeCl₃的萃取脱硫效果最佳,升高温度和增大剂油比均有利于脱硫率的提高,剂油比1:1(体积比)时,萃取时间达到12 min就可使脱硫率高达92%。且萃取反应完成后,离子液体不做处理继续重复使用,重复使用5次,脱硫率可以达到60%。     

Deep Desulfurization of Gasoline Fuel using FeCl3-Containing Lewis-Acidic Ionic Liquids

The FeCl₃-containing Lewis-acidic ionic liquids (ILs) [C₆mim]Cl/FeCl₃(1:1.5), [C₆mim]Cl/FeCl₃(1:2), [C₈mim]Cl/FeCl₃(1:1.5), and [C₈mim]Cl/FeCl₃(1:2) were used as extractants for desulfurization of model fuel and gasoline fuel, respectively. The results demonstrate that these ILs are effective for the removal of sulfur compounds from model fuel under different mass ratio of IL to model fuel (1:1, 1:3, 1:5, 1:10) at 25°C. The extractive performance of ILs increased as the molar ratio of FeCl₃ to [C_nmim]Cl(n = 6, 8) varied from 1:1 to 1:2. The selectivity of sulfur compounds by extraction process followed the order of dibenzothiophene (DBT)>benzothiophene (BT) > 4,6-dimethyldibenzothiophene (4,6-DMDBT). The sulfur removal of gasoline fuel containing sulfur content of 440.3 ppmw could be up to 85.8%; that is to say that the sulfur content of gasoline fuel varied from 440.3 ppmw to 62.4 ppmw after one extraction stage. Moreover, the [C₆mim]Cl/FeCl₃(1:2) can be recycled for at least 4 times with a little decrease in the desulfurization activity.     

Oxidative desulfurization of simulated light fuel oil and untreated kerosene

An experimental investigation was conducted on the oxidative desulfurization of model sulfur compounds such as dibenzothiophene and benzothiophene in toluene as a simulated light fuel oil with a mixture of hydrogen peroxide as the oxidant and various acids as the catalyst. The influences of various parameters including reaction temperature (T), acid to sulfur molar ratio (Acid/S), oxidant to sulfur molar ratio (O/S), type of acid, and the presence of sodium tungstate and commercial activated carbon as a co-catalyst on the fractional conversion of the model sulfur compounds were investigated. The experimental data obtained were used to determine the reaction rate constant of the model sulfur compounds and the corresponding activation energy. Moreover, the adsorption of model sulfur compounds on the commercial activated carbons supplied by Jacobi Co. (Sweden, AquaSorb 101) was studied and the effects of different parameters such as temperature, and various chemical treatments on the adsorption of the sulfur compounds were investigated. Furthermore, the oxidative desulfurization of untreated kerosene with the total sulfur content of 1700 ppmw produced by an Iranian refining company (Isfahan refinery) was successfully investigated. These experiments were performed using formic acid as the catalyst and hydrogen peroxide as the oxidant at the mild operating conditions of T = 50 °C, O/S = 5, and the Acid/S = 10. It was realized that about 87% of the total sulfur content of untreated kerosene could be removed after 30 min oxidation followed by liquid–liquid extraction.     

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。     

模拟轻质油氧化脱硫研究

以KMnO4为氧化剂,考察了KMnO4/HCl体系对模拟轻质油中苯并噻吩(BT)及二苯并噻吩(DBT)的氧化性能。在反应温度为25℃,反应时间为30 min,KMnO4的加入量为0.01 g/mL油,体系pH=0,V(油)∶V(HCl)=3∶4,相转移催化剂四丁基溴化铵(PTC)的加入量为0.002 g/mL油的条件下,二苯并噻吩脱除率为98.5%,苯并噻吩脱除率为86.6%。对DBT氧化反应动力学进行了研究,得出反应的表观活化能Ea为55.23 kJ/mol,指前因子k0为4.88×108。     

离子液体用于燃油萃取脱硫的选择与过程优化

针对基于COSMO-SAC模型分子设计方法的准确性问题,采用离子液体脱硫机理分析和实验的方法对其进行了验证,即对[HMIM] [BF₄]、[HMIM] [PF₆]、[BMIM] [BF₄]、[BMIM] [PF₆]、[EMIM] [BF₄]、[EMIM] [PF₆] 6种离子液体作萃取剂时的脱硫效果进行了脱硫机理的分析和实验的验证,得到的脱硫性能排序与离子液体分子设计结果基本一致,且均认为[HMIM] [PF₆]脱硫率较高。以[HMIM] [PF₆]为萃取剂,通过液相色谱法测定萃取后的液相组成,考察萃取时间、萃取温度、剂油比3个因素对脱硫率、分配系数和选择性系数的影响。通过正交实验设计确定了萃取时间40 min、萃取温度20℃、剂油比2：1为较优操作条件,单次脱硫率为72.74%,四级萃取可将模型油的含硫量由1200 μg·g^-1降至6.98 μg·g^-1,符合国Ⅴ标准。     

银基活性炭对废轮胎热解油的吸附脱硫机理研究

废轮胎经热解制备得到热解油和热解炭,热解炭活化制得活性炭,并利用Ag⁺对活性炭进行改性制得Ag⁺改性活性炭（Ag/AC）,将Ag/AC用于热解油的吸附脱硫实验,并利用GC/MS对热解油中的含硫化合物进行了分析。研究结果表明：活性炭吸附脱硫的合适温度和时间分别为20℃和12 h,此时未改性活性炭的脱硫率为15.33%;而Ag/AC的脱硫率提高到了38.6%。GC/MS分析发现热解油中有机硫的主要存在形式为噻吩、2-甲基噻吩、苯并噻吩、二苯并噻吩和4,6-二甲基二苯并噻吩,其中二苯并噻吩（DBT）的GC含量最高,为2.57%。利用原位红外、核磁共振氢谱、ICP-OES和元素分析等检测手段,进一步探究了Ag⁺与二苯并噻吩模型化合物在溶液中的反应机理,研究发现：二苯并噻吩分子上存在S原子和苯环2个反应位点,当Ag⁺加入二苯并噻吩溶液后,Ag⁺与二苯并噻吩分子上的S原子或者苯环发生配位数为1的配位反应生成2种配合物,分子式分别为Ag（D_S）NO₃和Ag（D_C6H6）NO₃。     

Air‐promoted adsorptive desulfurization of diesel fuel over Ti‐Ce mixed metal oxides

Air‐promoted adsorptive desulfurization (ADS) of commercial diesel fuel over a Ti‐Ce mixed oxide adsorbent in a flow system is investigated in this work. The fresh/spent adsorbents were characterized using X‐ray absorption near edge structure spectroscopy. Results show that sulfoxide species are formed during air‐promoted ADS over Ti_0.9Ce_0.1O₂ adsorbent. Adsorption selectivity of various compounds in fuel follows the order of dibenzothiophene sulfone > dibenzothiophene ? benzothiophene > 4‐methyldibenzothiophene > 4,6‐dimethyldibenzothiophene > phenanthrene > methylnaphthalene > fluorene > naphthalene. The high adsorption affinity of sulfoxide/sulfone is attributed to stronger Ti‐OSR₂ than Ti‐SR₂ interactions, resulting in significantly enhanced ADS capacity. Adsorption affinity was calculated using ab initio methods. For Ti‐Ce mixed oxides, reduced surface sites lead to O‐vacancy sites for O₂ activation for oxidizing thiophenic species. Low temperature is preferred for air‐promoted ADS, and the Ti‐Ce adsorbent can be regenerated via oxidative air treatment. This study paves a new path of designing regenerable adsorbents. © 2014 American Institute of Chemical Engineers AIChE J, 61: 631–639, 2015     

Extractive Desulfurization of Fuel Oils with Thiazolium-Based Ionic Liquids

A new class of green solvents, known as ionic liquids (ILs), has recently been the subject of intensive research on the extractive desulfurization of fuel oils because of the limitation of the traditional hydrodesulfurization method in catalytically removing thiophenic sulfur compounds. In this work, four thiazolium-based ILs, that is, 3-butyl-4-methylthiazolium dicyanamide ([BMTH][DCA]), 3-butyl-4-methylthiazolium thiocyanate ([BMTH][SCN]), 3-butyl-4-methylthiazolium hexafluorophosphate ([BMTH][PF₆]), and 3-butyl-4-methylthiazolium tetrafluoroborate ([BMTH][BF₄]), are synthesized. The extractive capability of these ILs in removing thiophene (TS) and dibenzothiophene (DBT) from model fuel oils is investigated. [BMTH][DCA] and [BMTH][SCN] present better extractive desulfurization capability than [BMTH][BF₄] and [BMTH][PF₆], which may be ascribed to the additional π?π interaction between –C≡N (in [BMTH][DCA] and [BMTH][SCN]) and thiophenic ring (in TS and DBT); DBT in diesel fuel is more efficiently extracted than TS in gasoline. [BMTH][DCA] offers the best desulfurization results, where 64% and 45% sulfur removal are obtained for DBT and TS, respectively, at IL:oil mass ratio of 1:1, 25°C, 20 min. [BMTH][DCA] is thus selected to systematically investigate the effects of temperature, IL:oil mass ratio, initial sulfur content, multiple-extraction, and IL regeneration on desulfurization. The mutual solubility of [BMTH][DCA] with fuel oil is also determined. It is observed that the desulfurization capability is not too sensitive to temperature and initial sulfur content, which is desired in industrial application; the sulfur contents in gasoline and diesel fuel are reduced from 558 ppm to 20 ppm (after 5 cycles) and from 547 ppm to 8 ppm (after 4 cycles), respectively. This work may show a new option for deep desulfurization of fuel oils.     

Acylation desulfurization of oil via reactive adsorption

Excellent desulfurization is achieved via reactive adsorption using Friedel‐Crafts acylation materials, that is, acylating reagents and Lewis acids, such as acetyl chloride (AC) and AlCl₃, being named as acylation desulfurization (ACDS). For model oil, thiophenic compounds, namely, dibenzothiophene, benzothiophene, and thiophene, are removed completely by AC–AlCl₃ within 30 min at room temperature. In this process, thiophenic compounds are acylated by AC under the catalysis of AlCl₃, and the acylated derivatives are stronger base than original ones due to incorporation of O‐containing carbonyl group (C?O) and, thus, adsorbed more easily by AlCl₃ via Lewis acid–base complexation. Further, ACDS mechanism is identified by acylated product characterization and quantum chemistry calculation. Satisfactorily, ACDS is still effective for toluene‐rich and real oils, and real oil quality is improved with desulfurization proceeding. © 2013 American Institute of Chemical Engineers AIChE J, 59: 2966–2976, 2013     

Sulfur removal from hydrotreated petroleum fractions using ultrasound-assisted oxidative desulfurization process

Ultrasound-assisted oxidative desulfurization (UAOD) process was applied to diesel oil and petroleum product feedstock containing model sulfur compounds (benzothiophene, dibenzothiophene and dimethyldibenzothiophene). The influence of oxidant amount, volume of solvent for the extraction step and time and temperature of ultrasound treatment (20 kHz, 750 W, operating at 40%) was investigated. Using the optimized conditions for UAOD, sulfur removal up to 99% was achieved for model compounds in petroleum product feedstock using a molar proportion for H₂O₂:acetic acid:sulfur of 64:300:1, after 9 min of ultrasound treatment at 90 °C, followed by extraction with methanol (optimized solvent and oil ratio of 0.36). Using the same reagent amount and 9 min of ultrasound the removal of sulfur was higher than 75% for diesel oil samples. Sulfur removal without ultrasound using the same conditions was lower than 82% for model compounds and 55% for diesel oil samples showing that ultrasound improved the efficiency of oxidative desulfurization. In comparison to conventional hydrodesulfurization, the proposed UAOD process can be performed under relatively mild conditions (atmospheric pressure and 90 °C, without using metallic catalysts).     

Fe基离子液体中Schiff碱Co络合物催化氧化燃油脱硫

将离子液体FeCl3/BmimCl与Schiff碱Co络合物CoL组成催化体系,以氧气为氧化剂,噻吩的正辛烷溶液为模拟油,考察该脱硫体系脱除模拟油中噻吩硫的性能。结果表明,最佳脱硫条件为：模拟油25mL;IL-FeCl3/BmimCl摩尔比为1,8mL;O250mL/min;反应温度62℃;CoL0.13g;时间6h,最终脱硫率可达96%（质量分数）,脱硫后油品中噻吩含量最终可降到50μg/g以下。噻吩的氧化产物为SO42-离子。离子液体再生4次后脱硫性能开始下降。该脱硫体系对实际柴油中的噻吩硫催化氧化脱硫效果可达100%,该脱硫体系具有实际应用意义。     

Polyoxometalate-based ionic liquids as catalysts for deep desulfurization of fuels

In order to obtain the ultra low-sulfur diesel, deep desulfurization of diesel oil has become a vital subject of environmental catalysis studies. Extraction and catalytic oxidation desulfurization (ECODS) system is one of the most promising desulfurization processes. A series of Keggin-type POM-based ionic liquids hybrid materials [MIMPS]₃PW₁₂O₄₀·2H₂O (1-(3-sulfonic group) propyl-3-methyl imidazolium phosphotungstate), [Bmim]₃PW₁₂O₄₀ (1-butyl 3-methyl imidazolium phosphotungstate), [Bmim]₃PMo₁₂O₄₀ (1-butyl 3-methyl imidazolium phosphomolybdate) and [Bmim]₄SiW₁₂O₄₀ (1-butyl-3-methyl imidazolium silicotungstate) have been developed in this study, and the reaction has performed using the POM-ILs materials as catalysts, H₂O₂ as oxidant, and ionic liquid (IL) as solvent. Through experimental evaluations, [MIMPS]₃PW₁₂O₄₀·2H₂O was found to be the best catalyst, with an S-removal of 100% at 30 °C for 1 h. The main factors affecting the process including temperature, catalyst dosage, and O/S (H₂O₂/DBT) molar ratio were investigated in detail. Under the optimal conditions, DBT (dibenzothiophene) and 4,6-DMDBT (4,6-dimethyl-dibenzothiophene) could achieve high desulfurization efficiency. Moreover, the reaction system also exhibited high activity in actual diesel oil, which could be reduced from 1113 ppm to 198 ppm. The reaction system could recycle 8-times with a slight decrease in activity.     

Synthesis of highly dispersed phosphotungstic acid encapsulated in MIL-100(Fe) catalyst and its performance in heterogeneous oxidative desulfurization

Highly efficient HPW(x)/MIL-100(Fe) catalysts with different phosphotungstic acid (HPW) loading (x, wt%) were successfully synthesized by a one-step hydrothermal method and characterized by XRD, SEM, FTIR, and BET. The influences of HPW loading, catalyst dosage, temperature, and O/S molar ratio on oxidative desulfurization (ODS) were investigated. The results indicated that the HPW(x)/MIL-100(Fe) retained the structure of its parent MIL-100(Fe). The MIL-100(Fe) presented a high surface area, which is beneficial to dispersion of HPW. The HPW(x)/MIL-100(Fe) with HPW loading of 40% exhibited excellent ODS activity. At a temperature of 50?°C, a catalyst dosage of 0.06?g, and an O/S molar ratio of 4, 100% desulfurization was achieved within 90?min for benzothiophene, dibenzothiophene, and 4,6-dimethyl-dibenzothiophene. The high catalytic activity of HPW(x)/MIL-100(Fe) can be attributed to highly dispersed HPW active sites with a high specific surface area.