Hierarchical macro-mesoporous Mo/Al2O3 catalysts prepared by dual-template method for oxidative desulfurization

Journal of Porous Materials - A series of Al2O3 materials with hierarchical macro-mesoporous structure were synthesized by a dual-template method, using surfactant Pluronic P123 and polystyene (PS)...     

低温等离子体催化氧化柴油脱硫工艺的研究

利用浸渍法制备了Cu~(2+)/Al_2O_3、Ni-Mn为主要组分的催化剂,并用其为催化剂、市售0~#柴油为对象探讨了等离子体催化氧化-萃取脱硫上艺.结果表明该催化剂的催化效果优于其他催化剂.当电极两端电压为17 kV、驱动频率为15 kHz、催化剂用量为5%质量分数、氧化时间为20 min、萃取剂为甲醇、剂/油体积比为1:1、萃取时间为15 min时,一级脱硫率可达到73.8%.     

Ultra-deep catalytic adsorptive desulfurization of diesel fuel using Ti-silica gel adsorbent at low Ti-loading

In this work, the effective ultra-deep catalytic adsorptive desulfurization (CADS) using titanium-silica gel (Ti-SG) adsorbent at low Ti loading (<1 wt.%) was investigated. The superior CADS capacity (37.3 mg-S/g-A) and high TOF value (432 h⁻¹) for dibenzothiophene (DBT) of Ti-SG adsorbent were achieved at Ti loading of 0.6% with high dispersion and low titanium coordination. The rate equation of catalytic DBT oxidation was described as , where the TiOOR was determined as the intermediate to enable the DBT oxidation to form the corresponding sulfone (DBTO₂). The effectiveness of CADS using Ti-SG adsorbents was verified in real diesels with varied sulfur concentrations and O/S ratios in the dynamic adsorption and multicycle regeneration. This work provides insights on using low-cost bifunctional catalytic adsorbents at low Ti loadings for effective CADS to realize ultra-deep desulfurization of transportation fuels.     

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。     

Oxidative desulfurization of diesel fuel by mesoporous phosphotungstic acid/SiO2: the effect of preparation methods on catalytic performance

Two kinds of mesoporous phosphotungstic acid/SiO₂ (HPW/SiO₂) have been synthesized by amino-functionalized (AF) method and evaporation-induced self-assembly (EISA) method, and their catalytic performance was investigated for deep oxidative desulfurization of benzothiophene (BT), dibenzothiophene (DBT) and 4,6-dimethyldibenzothiophene (4,6-DMDBT) in diesel oil. Various analysis techniques such as XRD, TEM, N₂ adsorption/desorption isotherms, FT-IR and ³¹P MAS NMR spectra have been used to investigate the pore structure and chemical properties of the resultant catalysts. The structural and spectroscopic analysis indicates both catalysts have a highly ordered 2D hexagonal mesostructure. HPW/SiO₂-EISA can maintain the Keggin structure of HPW molecules and has a high BET surface area (403 m²/g). But in the AF method, the mesostructure of SBA-15 are partially blocked after the introduction of HPW molecules, and the Keggin structure of HPW molecules has been damaged. The catalytic performance results also show that HPW/SiO₂-EISA exhibits higher catalytic activity and stability compared to HPW/SiO₂-AF. As for HPW/SiO₂-EISA, the conversions of DBT, 4,6-DMDBT and BT are found to be 99.6, 97.6, 94.8 %, respectively. It shows a good maintenance of activity even after the 7th cycle of use. While corresponding conversions by using HPW/SiO₂-AF are found to be 90.2, 89.1 and 87.6 %, and the DBT conversion decreases to 75.7 % after the 5th cycle of use.     

FCC柴油氧气氧化萃取法脱硫研究

以氧气作氧化剂,甲酸作催化剂,N-甲基吡咯烷酮(NMP)作萃取剂,采用催化氧化反应与溶剂萃取相结合的方法对催化裂化柴油进行了氧化萃取脱硫实验。通过单因素实验考察了催化剂用量、催化氧化温度、时间、氧气压力及萃取剂的用量等对催化裂化柴油硫质量分数的影响。通过实验得出最适宜的脱硫条件为:反应温度80℃,反应时间90 min,充氧压力0.6 MPa,V(催化剂)∶V(柴油)=10%。经催化氧化,柴油硫质量分数可从1 694.2μg/g降到190.8μg/g,脱硫率达到88.7%;在V(萃取剂)∶V(柴油)=1.0和室温条件下,用NMP萃取3次,柴油硫质量分数为37.5μg/g,小于50μg/g,达到欧Ⅳ排放标准的要求。     

The effect of Pd/Al2O3 pretreatment on catalytic activity in cyclopentane/deuterium exchange

Big variations in overall activity and product selectivity in the cyclopentane/deuterium exchange reaction were found in effect of various pretreatments of two chlorine‐free Pd/γ‐Al₂O₃ catalysts. The most important changes are observed when severely prereduced (at 600 °C) Pd/Al₂O₃ catalysts have been reoxidised and mildly rereduced: the multiple type of exchange, typical of mildly pretreated Pd catalysts, is replaced by a stepwise mode, and a big increase in catalytic activity occurs. At this state, the Pd/γ‐Al₂O₃ catalysts retain some water (as surface hydroxyls) generated by reoxidation and mild reduction. Deuterium spillover from Pd onto alumina and changes in acidity of alumina are invoked to rationalize the kinetic results. Changes in the state of Pd after various pretreatments, as probed by temperature‐programmed hydride decomposition, can hardly be correlated with changes in the catalytic behaviour in the exchange reaction. This revised version was published online in August 2006 with corrections to the Cover Date.     

氧化铝载体对镍/氧化铝催化剂性能的影响

氧化铝是化工催化行业广泛应用的催化剂载体。油脂加氢催化剂主要是以氧化铝为载体、镍为主要活性组分的催化剂。在制备镍/氧化铝催化剂的过程中,载体氧化铝使用的最佳条件：载体在共沉淀反应前加入,载体氧化铝比表面积为340.6 m2/g,载体氧化铝加入量为m（镍）∶m（氧化铝）=5∶4,反应的老化时间为45 min。在此条件下,制备的镍/氧化铝催化剂活性最高,应用效果最好。     

TiO_2对Ag/Al_2O_3吸附剂的柴油吸附脱硫性能的影响

采用浸渍法制备不同Ti O2含量的Ag/Ti O2-Al2O3吸附剂,以含硫量为245.36 mg·L-1的商品柴油作为考察对象,常温、常压条件下采用静态评价进行吸附脱硫性能研究。结果表明,经过Ti O2改性的Ag/Al2O3吸附剂柴油吸附脱硫活性有较大幅度提高。通过X射线衍射、N2物理吸附、O2化学吸附和NH3程序升温脱附等研究Ti O2改性剂的影响。关联活性测试和表征结果发现,吸附剂的吸附脱硫活性受吸附剂比表面积、活性金属Ag分散度和吸附剂表面酸协同影响。吸附剂比表面积越大,活性金属Ag分散度越高,吸附剂表面弱酸性位点数量越多,强酸性位点数量越少,吸附剂吸附脱硫活性越高。2%Ag/4%Ti O2-Al2O3的吸附脱硫活性最高,饱和硫容达2.11 mg·g-1。     

功率超声辅助下柴油氧化脱硫的研究

催化氧化脱硫是降低柴油硫含量的非加氢脱硫工艺,在催化氧化溶剂抽提的基础上,同时增加超声波为反应提供能量,开辟了一条全新的柴油氧化脱硫技术。考察了萃取剂的选择、萃取剂油比、萃取静置时间、萃取次数等对脱硫效果的影响。实验结果表明：在功率超声作用下,以H2O2为氧化剂,甲酸和磷酸为催化剂,氧化剂油比（体积比）=1：10,H2O2：催化剂（体积比）=1：1,反应温度50℃,反应时间10min时,萃取剂为DMF,萃取剂油比（体积比）=1：1,一次萃取20min,萃取次数2次为最佳。     

基于镁铝水滑石的Mo/Al2O3-MgO催化剂制备及其加氢脱硫性能

生产低硫或无硫柴油是当今世界范围内清洁燃料发展的趋势,加氢脱硫（HDS）是大规模生产清洁柴油最为有效的技术之一,而研制高活性的HDS催化剂成为该技术的关键。以镁铝水滑石与氧化铝的复合氧化物为载体,通过等体积浸渍法制备了一系列Mo/Al₂O₃-MgO催化剂,以二苯并噻吩（DBT）的正庚烷溶液为原料,在固定床反应器上评价所得催化剂的HDS活性,考察了不同镁铝比的水滑石、焙烧温度和添加量对催化剂物化性质和催化性能的影响。研究结果表明,镁铝比、焙烧温度和添加量均影响催化剂的酸性、金属还原性、硫化性能和MoS₂片晶的堆垛度等,当镁铝摩尔比为3、焙烧温度为800℃、成型时水滑石加入量为10%（质量分数）时,所制备催化剂的HDS活性最高,其脱硫率可达96.2%。这是由于该催化剂的酸性较适宜,活性组分与载体间的相互作用力适中,活性组分更易硫化,有助于提高MoS₂片晶的堆垛度进而改善催化剂的HDS性能。     

Investigation of the promotion effect on the sulfide sulfur mobility and on the catalytic activity of hydrotreating Co/Mo/Al2O3 catalysts using35S

Alkali nitrate promoted Raney Ru catalysts were prepared by hydrogenolysis of alkali nitrates (CsNO₃, RbNO₃, KNO₃, and NaNO₃) over Raney Ru. These catalysts were even more active in ammonia synthesis than Raney Ru promoted with metallic potassium. The promotion behaviour was different from that for the supported Ru catalysts, where metallic potassium was more effective than CsNO₃. Per-weight activity of CsNO₃ promoted Raney Ru was higher than that for any catalysts so far reported in ammonia synthesis under 80 kPa and at 573 K.     

Enhanced catalytic activity of Pt/Al2O3 on the CH4 SCR

In this study, we investigated the effect of mixing α-Al₂O₃ and γ-Al₂O₃ with a Pt catalyst on CH₄ selective catalytic reduction (SCR). Among the prepared catalysts, the Pt/α-Al₂O₃ catalyst was found to have the lowest catalytic activity, but the best adsorption characteristics for CH₄, which was used as the reductant. In contrast, the Pt/γ-Al₂O₃ catalyst was found to exhibit relatively high catalytic activity and moderate adsorption characteristics. To simultaneously enhance the catalytic activity and CH₄ adsorption characteristics, we developed a new catalyst, Pt/γ-Al₂O₃ + Pt/α-Al₂O₃, by mixing α-Al₂O₃ and γ-Al₂O₃ with a Pt catalyst. The catalytic activity test confirmed that mixing these catalysts led to enhanced catalytic activity.     

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&#8226;g^-1的柴油降低至小于10 μg&#8226;g^-1,可将初始硫浓度为320 μg&#8226;g^-1的汽油降低至155 μg&#8226;g^-1。     

纳米银催化剂Ag/Al_2O_3的制备及其催化活性研究

纳米银具有优良的催化性能,可催化多种化学反应。利用聚乙烯吡咯烷酮(PVP)作为还原剂和表面活性剂,通过水热合成法还原氧化银制备纳米银。用吸附色谱柱法将钠米银吸附在Al2O3上制得Ag/Al2O3催化剂,以此催化Se6+还原反应。结果表明,Ag/Al2O3具有良好的催化活性,能催化Se6+还原为Se、H2Se。     

K_2FeO_4催化氧化戊烷超深度脱硫技术

采用改进的次氯酸盐氧化法合成了高铁酸钾氧化剂,并对其进行了表征。提出了以高铁酸钾为氧化剂的高效、清洁氧化生产超低硫戊烷新方法,考察了氧化反应条件对脱硫效果的影响,并给出了氧化脱硫反应机理。在戊烷20 mL、K₂FeO₄ 0.1786 g、催化剂ZSW-1 0.5 mL条件下,30 ℃下氧化60 min后,反应产物采用5％的NaOH萃取,戊烷中硫含量由50 mg/L降到0.632 mg/L,脱硫率为98.7％。     

Mechanisms of hydrodenitrogenation of alkylamines and hydrodesulfurization of alkanethiols on NiMo/Al2O3, CoMo/Al2O3, and Mo/Al2O3

The simultaneous hydrodenitrogenation (HDN) of alkylamines and hydrodesulfurization (HDS) of alkanethiols, with the NH₂ and SH groups attached to primary, secondary, and tertiary carbon atoms, were studied at 270–320 °C and 3 MPa over sulfided NiMo/Al₂O₃, CoMo/Al₂O₃, and Mo/Al₂O₃ catalysts. Pentylamine and 2-hexylamine reacted by substitution with H₂S to form alkanethiols and with another amine molecule to form dialkylamines. Alkenes and alkanes were not formed directly from pentylamine and 2-hexylamine, but indirectly by elimination and hydrogenolysis of the alkanethiol intermediates, as confirmed by their secondary behavior and the similar alkene/alkane ratios in the simultaneous reactions of amines and thiols. Only 2-methyl-2-butylamine, with the NH₂ group attached to a tertiary carbon atom, produced alkenes as primary products by E1 elimination. NiMo/Al₂O₃ and CoMo/Al₂O₃ have a higher activity for the HDS of alkanethiols than does Mo/Al₂O₃; H₂S has a negative influence. This shows that the thiols react on vacancies on the catalyst surface (Lewis acid sites). Mo/Al₂O₃ is the best HDN catalyst; H₂S has a positive influence on the HDN of amines with the NH₂ group attached to a secondary and a tertiary carbon atom. This indicates that the HDN of alkylamines occurs on Brønsted acid sites.     

Al_2O_3-H_2O纳米悬浮液导热系数研究

采用瞬变平面热源法测量了纳米Al2O3粉体分散于去离子水制备成的悬浮液的导热系数,分析了悬浮液的pH、分散剂的质量份额、纳米Al2O3粉体的质量份额等因素对悬浮液导热系数的影响。结果表明:在pH为8左右的时候,纳米Al2O3-H2O悬浮液的导热系数较大;悬浮液的导热系数随纳米Al2O3质量份额的增加而增加;在Al2O3纳米颗粒与SDBS分散剂质量分数比为1∶1时,悬浮液的导热系数较大,随着分散剂质量分数的增加,悬浮液的导热系数降低。     

Effect of the electronic properties of Mo sulfide phase on the hydrotreating activity of catalysts supported on Al2O3, Nb2O5 and Nb2O5/Al2O3

Activity in thiophene hydrodesulfurization (HDS) and in the three routes of 2,6-dimethylaniline (DMA) decomposition was examined on Mo sulfide catalysts supported on Al₂O₃, Nb₂O₅ and Nb₂O₅–Al₂O₃. Catalysts activity is enhanced when Mo phase is deposited on niobium-containing support. For HDS and for the hydrogenation route of DMA decomposition, the niobium-containing support strongly contributes to the catalyst activity whereas the activity of the Mo phase per Mo atom decreases with the increase of niobium amount in the support. By contrast, as for the DMA route, which leads to xylene formation (XYL), the activity of the Mo sulfide phase per Mo atom is strongly enhanced. The electronic properties of the MoS₂ phase were studied by means of IR spectroscopy of CO adsorption. Comparison of ν(CO/Mo) wavenumbers reveals an upward shift when Mo sulfide phase is deposited on Nb-containing support. The modification of the electronic properties of the sulfide phase is related to an interaction Mo–Nb either through the formation of a mixed Mo–Nb sulfide phase, or through the interaction MoS₂ slabs – support whose strength depends on the support acidity. Hence, the beneficial effect for xylene formation route is attributed to a decrease of the electron density of the Mo sulfide phase that should strengthen the DMA adsorption on the sulfide phase.     

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.