Methane steam reforming over rhodium promoted Ni/Al2O3 catalysts

The effect of Rh addition upon catalyst characteristics and performance in methane steam reforming was investigated using Rh-promoted Ni/Al₂O₃ catalysts. The number of reduced metal atoms exposed on the surface increased for the Rh-promoted catalysts. Rh-promoted catalysts showed an increase in CH₄ reforming activity; however, constant turnover frequencies for promoted and unpromoted catalysts suggest that the increase in the number of metal surface atoms caused the activity enhancement. Rh also facilitated reduction of Ni/Al₂O₃.     

Fischer-Tropsch synthesis over Ru/Al2O3 catalysts

Fischer-Tropsch syntheses (FTS) were carried out in a slurry phase over Ru/Al₂O₃ catalysts using hexadecane as a solvent. The outcome of the FTS was dependent on the oxide support, calcination temperature, synthesis gas composition and sulfur content. The addition of Mn/Na to Ru/Al₂O₃ was effective in raising the initial activity and C5+ selectivity, but after 20 hours, the performance of the modified catalyst was similar to that of the unmodified catalyst. An additional investigation involving the use of fresh vs used catalysts demonstrated that an agglomeration of the metallic Ru, at least in part, does occur during the reaction.     

Hydrogenation of nitrate in water over bimetallic Pd-Ag/Al2O3 catalysts

Hydrogenation of nitrate (NO₃ ⁻) in water was studied with 0.8 ×10⁻³–3.2 ×10⁻³ mol/dm³ of reactant in the temperature range of 293–313 K over palladium promoted Ag catalysts. Pd-Ag catalysts with a low ratio of Ag/Pd were characterized by high efficiency in the reduction of nitrates. The degradation of nitrates followed approximately first order decay and the estimated apparent activation energy was about 4 kJ/mol.     

系列硅铝比纳米薄层ZSM-5分子筛的合成和表征

以自制不对称双子季铵盐表面活性剂为模板, 在水热合成体系中控制合成系列硅铝比纳米薄层ZSM-5分子筛.采用X射线衍射(XRD)、N₂吸附-脱附、X射线荧光光谱(XRF)、扫描电镜(SEM)和²⁷Al魔角旋转核磁共振(²⁷Al MAS-NMR)对合成的样品进行了表征. 详细研究了晶化温度、晶化时间、结构导向剂(SDA)用量、碱度等对合成的影响和纳米薄层ZSM-5分子筛的形成过程. 结果表明: 分子筛硅铝比越高, 结构导向剂用量越大, 所需的晶化时间越短; 晶化温度越高, 晶化时间越短; 且不同硅铝比纳米薄层ZSM-5分子筛的形貌规整度、比表面积和介孔/微孔孔容比例随着硅铝比而变化.     

Activity of bifunctional Pt-Dy/Al2O3 catalysts in hydrocarbon reactions

The conversions ofn-hexane and methylcyclopentane on Pt–Dy/Al₂O₃ containing different amounts of Dy have been investigated in a pulsed microcatalytic reactor. The poisoning effect of thiophene on the activity of Pt–Dy/Al₂O₃ for n-hexane conversion has been studied. The influence of Dy over Pt–Dy/Al₂O₃ is also discussed.     

Fe2O3/Al2O3二元气凝胶合成高质量单壁纳米碳管

通过溶胶和超临界干燥方法制得了Fe₂O₃/Al₂O₃二元气凝胶，其比表面积和孔隙体积分别为246 m²·g^-1和1.89 cm³·g^-1，并具有较宽的孔径分布。以Fe₂O₃/Al₂O₃二元气凝胶作催化剂，通过甲烷催化裂解成功地合成了高质量的单壁纳米碳管。利用FESEM、TEM和HRTEM、Raman光谱等分析手段研究了反应温度对单壁纳米碳管生长的影响。结果表明在900 ℃时合成单壁纳米碳管的质量较高，并且合成的炭产物为毡状，该炭产物主要为高质量的单壁纳米碳管。     

Gas-phase phenyl acetate conversion on AlPO4, γ-Al2O3 and SiO2 catalysts

The conversion of phenyl acetate over AlPO₄ (Al/P=1), γ-Al₂O₃ and SiO₂ catalysts generated phenol, by deacetylation, ando-hydroxycetophenone, by Fries rearrangement, as the main reaction products. The activity for Fries rerrangement was in accordance with the acidity data measuredversus cyclohexene skeletal isomerization. Thus, AlPO₄ showed the highest activity. Moreover,o-hydroxy-acetophenone formation increased with the reaction temperature. Besides, in AlPO₄ catalysts 4-methylcoumarin and 2-methylchromone were also found, although in low amounts.     

Characterization of Cu-ZnO-Cr2O3/SiO2 catalysts and application to dehydrogenation of 2-butanol to 2-butanone

The Cu-ZnO-Cr₂O₃/SiO₂ catalysts were prepared by impregnation method, which exhibited high activity for the dehydrogenation of 2-butanol to 2-butanone. These catalysts were characterized by means of XRD, EPR and BET. The experimental results indicated that (i) the valence states of copper play a key role, (ii) groups of copper atoms were the main active sites in this reaction, and (iii) copper oxide would lead to the condensation product of 5-methyl-3-heptanone.     

纳米膜组装介孔Al2O3：合成及Pt/Al2O3的硝基苯催化加氢性能

以"乙酸乙酯(EA)-偏铝酸钠-水"体系在室温下合成了纳米膜组装介孔Al2O3。研究发现:合成反应时间、静置前搅拌时间、NaAlO2用量、EA用量及反应温度等对合成产物的形貌有影响;另外,与用商品γ-Al2O3制备的Pt/γ-Al2O3催化剂相比,纳米膜组装介孔Al2O3制备的Pt/Al2O3催化剂含有部分易被还原的PtOx物种。在硝基苯催化加氢反应中,用合成Al2O3为载体制备的Pt/Al2O3催化剂,比用商品γ-Al2O3制备的Pt/γ-Al2O3催化剂具有更好的催化活性。     

Selective oxidation of octadecan-1-ol to octadecanoic acid over Co3O4/SiO2 catalysts

Factors (reaction temperature, reaction time, flow rate of oxygen, amount of catalyst, etc.) influencing the catalytic properties of Co₃O₄/SiO₂catalyst in the oxidation octadecan-1-ol to octadecanoic acid were investigated. The catalysts were characterized by means of XRD, FT-IR and N₂-adsorption. The experimental results indicate that under the optimal condition the selectivity to octadecanoic acid reached 97.5 % over 5 % Co₃O₄/SiO₂ catalyst.This revised version was published online in December 2005 with corrections to the Cover Date.     

Preparation, characterization and application of KNH2/Al2O3 and KF/Al2O3 as strong solid bases

This review describes the preparation, characterization and application of KNH₂ loaded on alumina and KF loaded on alumina. These strong solid bases catalyze a variety of organic reactions in a very selective manner. The reactions include isomerizations of alkenes and alkynes, dimerization of alkynes, Tishchenko reaction, and the reaction of silanes to form of Si–C, Si–N and Si–O bonds.     

不同磷含量对NiMoP/Al2O3加氢处理催化剂的影响

采用NiMoP浸渍液浸渍载体γ Al₂O₃制备了不同磷含量的NiMoP/Al₂O₃加氢处理催化剂。为了研究磷对该系列催化剂活性相结构的影响,用二苯并噻吩（DBT）和喹啉为模型化合物,考察了催化剂的加氢脱硫（HDS）和加氢脱氮（HDN）性能。结果表明,添加适当的磷能够提高催化剂的HDS和HDN活性,但是高含量的磷能显著的降低催化剂的催化性能。通过对催化剂进行XRD和HRTEM表征发现,添加磷能够增加MoS2的堆积层数以及Ⅱ型“Ni-Mo-S”相的相对含量,这是因为在制备过程中添加磷降低了活性组分与载体之间的相互作用。     

The Al2O3-Fe2O3 Mixed Oxidic System, I. Preparation and Characterization

A series of Al₂O₃-Fe₂O₃ mixed oxidic solids with composition ranging from 0 to 100% of Fe₂O₃ were prepared and examined for structural characteristics. XRD diagrams showed the presence of α-Al₂O₃ and hematite phases. The analysis of M?ssbauer spectra revealed the existence of two iron containing phases. The specific surface area of the mixture decreases by the addition of iron and depends on the crystal phases of the mixture. This revised version was published online in June 2006 with corrections to the Cover Date.     

Al2O3-ZrO2复合膜的制备与表征

以异丙醇铝和氧氯化锆为原料,用溶胶-凝胶法在Al₂O₃中空纤维上制备了Al₂O₃-ZrO₂复合膜。应用TG、DTA、XRD、SEM等测试手段对复合膜的热稳定性、结构、形貌进行了表征。结果表明复合膜的热稳定性比单一由氧化铝或氧化锆制成的膜有显著的提高,在1100℃之前,复合膜以t-ZrO₂存在,1200℃时,出现了m-ZrO₂和α-Al₂O₃相。扫描电镜分析表明,膜表面完整、无缺陷。气体渗透实验进一步表明所得膜具有一定的气体选择性,0.3MPa和0.5MPa下对氮气和氩气的分离因子α分别为1.191和1.185,和氮气与氩气的理论分离因子(α=1.194)相当,说明气体通过膜的扩散以Knudsen扩散传质为主。用等温氮气吸附实验测定了非担载膜的孔径大小和分布,最可几孔径约为4.3nm。     

Enhancing effect of water vapor on the reduction of lean NOx by ethanol over an Ag/Al2O3 catalyst supported on cordierite honeycomb

The Ag/Al₂O₃ catalyst supported on cordierite honeycomb (Ag/Al₂O₃/ cordierite) is highly active forthe reduction of lean NOx by ethanol. Addition of H₂O enhances the NOx reduction to CO₂ and N₂, and suppresses the formation of by-products such as CO, CH₃CHO and C₂H₄.     

Mn修饰Al2O3载体负载Pd催化剂及其蒽醌加氢催化性能

以活性氧化铝(γ-Al2O3)为载体,分别以Mn(NO3)2溶液和酸性氯化钯(PdCl2)溶液为修饰组分和活性组分前体,采用分步浸渍法制备了Mn修饰Al2O3载体负载钯催化剂。将催化剂应用于蒽醌加氢反应,考察了催化剂制备方法、活性组分负载量和催化剂还原温度对反应效果的影响。用XRD、BET、XPS和TPR对催化剂进行了表征。结果表明,催化剂活性受到制备方法的影响,在对Mn修饰Al2O3载体进行焙烧,Pd负载量0.2(wt)%、还原温度300℃的条件下,催化剂蒽醌加氢活性较高,较未修饰的催化剂提高了约16%。催化剂中Mn以MnO的形式存在,影响了γ-Al2O3的组织结构,使载体与活性组分之间的作用力增强,活性组分Pd高度分散在催化剂表面,从而提高了催化剂的活性。     

Photodegradation of 2,4-D over PdO/Al2O3-Nd2O3 photocatalysts prepared by the sol-gel method

The photocatalytic activity of 1.0 wt% PdO supported on Al₂O₃-Nd₂O₃ binary oxides prepared by the sol-gel method was studied in the photodegradation of 2,4-dichlorophenoxyacetic acid (2,4-D). The photocatalysts were characterized by N₂ physisorption, XRD and UV-vis spectroscopy. PdO supported on γ-Al₂O₃ photo-degrades the 2,4-D, however the addition of Nd₂O₃ to γ-Al₂O₃ notably improves the photocatalytic activity. As the concentration of Nd₂O₃ in the binary oxide increases from 2 to 10 wt%, the photodegradation of 2,4-D is highly enhanced. The catalytic test for PdO supported on pure Nd₂O₃ showed scarce photocatalytic activity. Total organic carbon (TOC) analysis showed that the 2,4-D has been completely destroyed on the PdO/Al₂O₃-Nd₂O₃ photocatalysts after 6 h under irradiation.     

SiO2-Supported Highly Dispersed Rh Catalysts

A series of Rh/SiO₂ catalysts were prepared by a sol-gel method, characterized by N₂ physical adsorption, H₂ chemisorption and FTIR, and studied in the hydrogenolysis of propane. The results show that rhodium exists in very high, nearly atomic dispersion in the catalysts after reduction; this was not obtained by conventional preparative methods. This revised version was published online in June 2006 with corrections to the Cover Date.     

Influence of the activation temperature on structural and textural properties of NiMo/Al2O3 hydrodesulfurization catalysts

Investigations of a commercial NiMo/Al₂O₃ hydrodesulfurization (HDS) catalyst are directed towards optimization of the activation procedure of HDS catalyst concerning active phase formation and thermal stability. Structural and textural data obtained with XRD, IR-FTIR, XPS and LTNA reveal that the optimal temperature for the formation of active species on the catalyst surface and an appropriate pore structure is 300°C.     

The role of the nano-environment of supported gold catalysts in the activity control. Modification of Au/Al2O3 catalysts by redox-type metal oxides

Au/Al₂O₃ catalysts were modified by different redox metal oxides, such as FeO_x, MnO_x and CoO_x, resulting in a pronounced activity increase in CO oxidation.