吸附法柴油脱硫技术进展

本文从吸附剂改性、吸附脱硫机理和吸附剂再生等方面综述了以活性炭、金属氧化物、分子筛等为吸附材料吸附脱除柴油中硫化物的最新进展。柴油中的含硫化合物主要包括无机硫和有机硫,其中有机硫占80％以上。在活性炭表面,金属氧化物或分子筛上负载过渡金属都可提高其对硫的吸附能力,π键配位吸附脱硫技术是脱除噻吩类硫化物的有效方法。吸附脱硫是一项具有发展潜力的脱硫技术,然而,要加速这一技术的工业化进程,开发对稠环噻吩类硫化物具有高选择性、高吸附量、易再生的吸附剂是当前面临的重要挑战。     

多孔炭吸附脱除噻吩类硫研究进展

综述了目前多孔炭吸附剂在脱除噻吩类硫化物中的应用,分别介绍了多孔炭及改性多孔炭在吸附脱硫中的应用。重点介绍了改性多孔炭包括氧化改性及金属改性法的活性炭和介孔炭吸附脱硫研究,指出采用氧化一金属复合改性活性炭的方法可显著提高吸附脱硫能力。介孔炭由于具有较高的比表面积、较窄的孔径分布、极好的化学和热稳定性,用在吸附脱硫将可能成为未来的研究热点。     

钒对FCC催化剂脱除噻吩类硫化物性能的影响

催化裂化过程(FCC)中使用催化剂脱硫对生产清洁燃料具有重要意义。文中通过文献调研,阐述了噻吩类硫化物在FCC催化剂上的裂化依赖于B酸和L酸的协同作用原理,指出以L酸碱对化合物修饰FCC催化剂可改善其表面的弱L酸分布,增强催化剂对噻吩类硫化物的选择性吸附能力,提高FCC催化剂脱除噻吩类硫化物性能。氧化钒作为典型的L酸碱对化合物,利用其修饰FCC催化剂可改善裂化催化剂的脱硫活性。鉴于氧化钒对FCC催化剂的活性组分分子筛存在一定的破坏作用,FCC催化剂的载体是较适宜的修饰位置。低价态钒较高价态钒对噻吩有着更强的化学吸附能力,因而采用还原预处理后的催化剂可得到较好的脱硫效果。     

活性炭催化氧化脱除汽油和柴油中噻吩类硫化物的选择性

研究了活性炭催化氧化脱除汽油和柴油中噻吩类硫化物的选择性。采用气相色谱-硫化学发光检测器（GC-SCD）分析了汽油和柴油中噻吩类硫化物的分布及浓度;以活性炭作为催化剂,以30％过氧化氢溶液为氧化剂,在甲酸存在条件下考察了汽油和柴油中噻吩类硫化物催化氧化脱除的选择性,讨论了硫化物中硫原子电子密度对硫化物氧化选择性的影响。结果表明：汽油中噻吩类硫化物主要有噻吩（T）及其烷基衍生物（T alkylated derivatives）和苯并噻吩（BT）;而柴油中噻吩类硫化物主要分布有苯并噻吩(BT)及其烷基衍生物(BT alkylated derivatives)和二苯并噻吩（DBT）及其烷基衍生物（DBT alkylated derivatives）;硫原子电子密度大于5.716的含3个C烷基噻吩（C3-T）、BT、BT alkylated derivatives、DBT 和DBT alkylated derivatives 能被催化氧化脱除,硫原子的电子密度越大,其被氧化的速率越快,被脱除的选择性也越大;被脱除选择性顺序为：DBT alkylated derivatives > DBT > BT alkylated derivatives> BT> C3-T;然而硫原子电子密度小于5.716的T,含1个烷基噻吩（C1-T）和含2个C烷基噻吩（C2-T）则不能被氧化脱除。采用此方法,能将初始硫浓度为1200 μg•g^-1的柴油降低至小于10 μg•g^-1,可将初始硫浓度为320 μg•g^-1的汽油降低至155 μg•g^-1。     

超临界甲醇中氧化脱除模型物中噻吩硫的研究

传统加氢脱硫往往难以脱除重油中的噻吩类硫化物。利用噻吩类硫化物氧化后的极性增加,在超临界甲醇条件下强化其在极性溶剂中的溶解度,可深度脱除重油中的噻吩硫。以二苯并噻吩(DBT)与十四烷为模型油,甲醇为超临界介质,考察了无催化时反应条件对超临界氧化脱硫性能的影响,不同催化氧化体系的脱硫效率。利用红外光谱、气相色谱-质谱联用对反应产物进行分析以研究脱硫机理。结果表明,在无催化时,反应温度260℃、反应压力8.5～9.0 MPa、反应时间3 h、过氧化二叔丁基作氧化剂且氧硫摩尔比为3:1时,噻吩模型物的脱硫率最高,达42%。在催化氧化体系中,催化剂用量与硫的摩尔比为1:10时催化剂使用效率最高,3种脱硫效果较好的催化氧化体系脱硫率分别达到了47%、45%、45%。FTIR、GC-MS结果表明二苯并噻吩被氧化为相应亚砜并转移至甲醇相,从而实现了硫化物的脱除。     

吸附脱硫及分子模拟计算应用的研究进展

综述了采用各种吸附方法脱除汽油、柴油中硫的研究进展。认为天然矿物及未改性商业分子筛具有价格便宜的优点,但本身脱硫性能不是很好;改性活性炭在硫化物吸附容量方面比较优良,但机械强度不高;金属氧化物及负载金属氧化物的多孔复合材料对硫化物的选择性较高,但吸附容量不大;以过渡金属离子改性分子筛,尤其是利用π络合脱硫的研究为以后柴油深度脱硫开拓了方向。指出吸附法结合其他脱硫工艺将是深度脱硫的重要研究方向之一;分子模拟应用于吸附脱硫的研究,将为脱硫吸附剂的开发提供新的途径。     

柴油深度脱硫技术研究进展

加氢柴油中残留的硫化物主要为二苯并噻吩及其衍生物,因此,脱除柴油中二苯并噻吩类硫化物是实现柴油深度脱硫的关键技术。系统地介绍了加氢脱硫、生物脱硫、氧化脱硫和吸附脱硫等技术及其优缺点,重点介绍了反应吸附脱硫技术的最新研究进展。     

负载型Ce、La催化氧化脱除柴油中有机硫化物

Ce基催化剂因其具有较强的储放氧功能,在催化氧化反应中有着广泛的应用。而其用于催化氧化脱除柴油中有机硫化物的研究,并未有报道。本文用负载法制备Ce、La高丰度稀土元素的催化剂,用于催化分子氧氧化脱除柴油中硫化物,旨在分析其催化氧化效果。结果表明:反应温度越高其催化氧化活性越大,柴油脱硫率最高达70%以上。     

车用燃料油中噻吩类硫化合物脱除技术进展

燃料油硫化物中的噻吩类硫化物较难脱除,采用经济、适用的噻吩类硫化物脱除技术是车用燃料油深度脱硫技术发展的必然趋势。介绍了加氧脱硫、非加氢脱硫、联合脱硫等噻吩类硫脱除技术,指出为了实现高效、经济、环保的目标,联合脱硫技术将得到更多使用,非加氢脱硫技术中的吸附脱硫、氧化脱硫在克服目前存在的技术问题后将有非常好的发展前景。     

车用燃料油中噻吩类硫化合物脱除技术进展

燃料油硫化物中的噻吩类硫化物较难脱除，采用经济、适用的噻吩类硫化物脱除技术是车用燃料油深度脱硫技术发展的必然趋势。本文介绍了加氢脱硫、非加氢脱硫、联合脱硫等噻吩类硫脱除技术，指出为了实现高效、经济、环保的目标，联合脱硫技术将得到更多使用，非加氢脱硫技术当中吸附脱硫、氧化脱硫在克服目前存在技术问题后将有非常好的发展前景。     

Desulfurization of transportation fuels targeting at removal of thiophene/benzothiophene

A new method is presented for deep desulfurization of transportation fuels targeting at the removal of thiophenic compounds. The method is based on a characteristic condensation reaction of thiophenic compounds with formaldehyde, and the reaction was designed to occur in the pore spaces of activated carbon under catalysis of sulfuric acid. The reaction is selective because the hydrocarbon components of fuels do not react with formaldehyde at the same condition. Therefore, the quality of fuel, e.g. the octane number, will not change, and the desulfurization function will not be interfered either by olefin/aromatic components or the dissolved water of fuels. Because the reaction is occurring in the pore spaces, the desulfurization function is locally intensified and the reaction products were there adsorbed. All those merits were shown firstly by different types of model fuels, and then by a commercial diesel fuel. In conjunction with an oxidation treatment, the total sulfur content of the commercial fuel dropped from 1697 ppm to 14 ppm, which meets the present fuel specification of the US.     

酸性离子液体和Na2WO4·2H2O催化

以酸性离子液体和Na₂WO₄·2H₂O组成的体系为催化剂，过氧化氢为氧化剂，将催化柴油中的噻吩硫氧化为砜类物质，并通过NMP将其萃取出来，同时考察了反应温度、反应时间和催化剂用量等因素对氧化脱硫反应的影响，得出最佳反应条件为：3 mL油样（含硫200 μg·g^_-1），1 g离子液体，0.021 g 钨酸钠（Na₂WO₄·2H₂O）， 0.7 mL过氧化氢，反应温度323 K，反应时间3 h，萃取剂与柴油体积比为1∶1，此时样品中的硫可降低到23 μg·g^-1。反应结束后，可以通过简单的倾倒将油样和催化剂分离，催化剂重复使用5次，催化活性基本不变。     

Two-step adsorption process for deep desulfurization of diesel oil

An integrated adsorption process for deep desulfurization of diesel fuel was proposed and examined. Conventionally hydrodesulfurized straight run gas oil (HDS-SRGO) having less than 50 ppm sulfur was also adsorptively treated with activated carbon fiber (ACF) to attain the ultra low sulfur gas oil having less than 10 ppm sulfur. The ACF, used in cleaning-up HDS-SRGO, was successively examined in straight run gas oil (SRGO) treatment to enhance its hydrodesulfurization (HDS) reactivity over conventional CoMo catalyst by removing the nitrogen and refractory sulfur species contained in SRGO. Such integrated adsorption–reaction process makes it possible to utilize the maximum adsorption capacity of ACF and achieve ultra deep desulfurization og SRGO. Regeneration of used ACF with a conventional solvent was proved very effective in restoring its adsorption capacity.     

Ultra-deep desulfurization and denitrogenation of diesel fuel by selective adsorption over three different adsorbents: A study on adsorptive selectivity and mechanism

Adsorptive desulfurization and denitrogenation were studied using a model diesel fuel, which contains sulfur, nitrogen and aromatic compounds, over three typical adsorbents (activated carbon, activated alumina and nickel-based adsorbent) in a fixed-bed adsorption system. The adsorptive capacity and selectivity for the various compounds were examined and compared on the basis of the breakthrough curves. The electronic properties of the adsorbates were calculated by a semi-empirical quantum chemical method and compared with their adsorption selectivity. Different adsorptive selectivities in correlation with the electronic properties of the compounds provided new insight into the fundamental understanding of the adsorption mechanism over different adsorbents. For the supported nickel adsorbent, the direct interaction between the heteroatom in the adsorbates and the surface nickel plays an important role. The adsorption selectivity on the activated alumina depends dominantly on the molecular electrostatic potential and the acidic–basic interaction. The activated carbon shows higher adsorptive capacity and selectivity for both sulfur and nitrogen compounds, especially for the sulfur compounds with methyl substituents, such as 4,6-methyldibenzothiophene. Hydrogen bond interaction might play an important role in adsorptive desulfurization and denitrogenation over the activated carbon. Different adsorbents may be suitable for separating different sulfur compounds from different hydrocarbon streams.     

Chemical desulfurization of petroleum fractions for ultra-low sulfur fuels

An improved desulfurization process for removing sulfur from hydro treated diesel oil based on the oxidation of thiophenic type sulfur-containing compounds with H₂O₂ and acetic acid (AcOH) using H₂SO₄ as catalyst has been studied. The experimental results show that the sulfone content in the oxidation product increased rapidly with an increase in acetic acid and sulfuric acid ratios from 1:0 to 2:1 mole ratios. The maximum DBT conversion (wt.%) was at 2:1 mole ratio of acetic acid/sulfuric acid. This oxidation process is found to be capable of removing up to 90% of the sulfur compounds in hydro treated real fuels and can provide an alternative way to meet the future sulfur environmental requirements.     

柴油电催化加氢与氧化脱硫的系统集成

柴油中硫和多环芳烃含量要求越来越严,由于二苯并噻吩类硫化物的空间位阻导致传统的催化加氢难以实现以上目标。本文以泡沫铅为阴极,以石墨为阳极,在CH₃CN+EtOH+H₂O+Bu₄NBr电解体系中可以将柴油中多环芳烃的电解加氢和含硫化合物的电解氧化脱除集成。在该电解体系中泡沫铅电极上柴油电解加氢主要是温和的加氢,电解加氢后氢含量增加了1.1%,三环芳烃蒽类和菲类减少3.3%,但是总芳烃含量变化不大,十六烷值增加3.9。在石墨阳极上柴油中硫化物容易电解氧化,氧化产物砜类不能完全由电解体系萃取脱除,进一步通过活性炭吸附可以将柴油硫含量由884 μg·g^-1降低至44 μg·g^-1。     

Diesel fuel desulfurization with hydrogen peroxide promoted by formic acid and catalyzed by activated carbon

Desulfurization of diesel fuels with hydrogen peroxide was studied using activated carbons as the catalysts. Adsorption and catalytic properties of activated carbons for dibenzothiophene (DBT) were investigated. The higher the adsorption capacity of the carbons is, the better the catalytic performance in the oxidation of DBT is. The effect of aqueous pH on the catalytic activities of the activated carbons was also investigated. Oxidation of DBT is enhanced when the aqueous pH is less than 2, and addition of formic acid can promote the oxidation. The effect of carbon surface chemistry on DBT adsorption and catalytic activity was also investigated. Adsorption of DBT shows a strong dependence on carboxylic group content. The oxidative removal of DBT increases as the surface carbonyl group content increases. Oxidative desulfurization of a commercial diesel fuel (sulfur content, 800 wt. ppm) with hydrogen peroxide was investigated in the presence of activated carbon and formic acid. Much lower residual sulfur content (142 wt. ppm) was found in the oxidized oil after the oxidation by using the hydrogen peroxide-activated carbon-formic acid system, compared with a hydrogen peroxide-formic acid system. The resulting oil contained 16 wt. ppm of sulfur after activated carbon adsorption without any negative effects in the fuel quality, and 98% of sulfur could be removed from the diesel oil with 96.5% of oil recovery. Activated carbon has high catalytic activity and can be repeatedly used following simple water washing, with little change in catalytic performance after three regeneration cycles.     

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.     

The application of theoretical solutions to the differential mass balance equation for modeling of adsorptive desulfurization in a packed bed adsorber

Adsorptive removal of organosulfur compounds, lumped as total sulfur content, from a real diesel fuel was carried out in a packed bed adsorber. A novel approach was taken in the application of theoretical solutions to the differential mass balance equation using modern software tools, and one classic method as point of reference. Adsorptive desulfurization is a perspective downstream process to hydrodesulfurization for achieving sulfur concentration levels of less then 10 mg kg⁻¹. Compared to the conventional hydrodesulfurization process, the deep desulfurization can be accomplished without changing the physical properties of the product and at relatively low temperature and pressure. The adsorber apparatus comprised computer control, enabling completely automated operation. Adsorbent was activated carbon SOLCARB C from Chemviron Carbon, Belgium. The experimental results regarding the influence of flow rate and bed depth on the outlet sulfur concentration were evaluated as well as the models ability to describe the adsorption kinetics and to estimate the breakthrough curves. Ultra deep desulfurization of diesel fuel was achieved and it was determined that outlet sulfur concentration was being lowered by decreasing flow rate and increasing bed depth. The closest fit to the experimental data was achieved for the Bohart-Adams model.