Ruthenium sulphide catalysts supported on alumina : physicochemical characterization and catalytic properties in hydrotreating reactions

Ruthenium sulphide catalysts supported on alumina were prepared using ruthenium III chloride trihydrate and they were sulphided under a N₂/H₂S(15%) flow at a number of temperatures. The properties of the catalysts in thiophene hydrodesulphurization, biphenyl hydrogenation and pyridine conversion have been investigated and interpreted in relation to their characterization by X-ray photoelectron spectroscopy, high resolution electron microscopic observations and temperature-programmed reduction data. The results show the importance of the sulphidation step in the genesis of different active RuS₂ particles. The relation between the activity and the nature of the exposed crystallographic planes is discussed.     

HDS,HDN and HDA activities of nickel–molybdenum catalysts supported on alumina

In this work, NiMo–Al₂O₃ catalysts were prepared by using different alumina precursors. The supports were impregnated by means of the spray at incipient wetness technique in both basic and acid media. Both the supports and fresh catalysts were characterized by the adsorption–desorption isotherms, Temperature-Programmed Reduction (TPR), Thermal Pyridine Adsorption–Desorption (TPD) and X-Ray Diffraction analyses (XRD). After sulfidation, the NiMoS metallic particles were characterized by Transmission Electron Microscopy (TEM). The initial analyses were performed in a trickle-bed reactor by using a real feedstock (Mexican heavy gas oil) and performing hydrotreating reactions (HDS, HDN and HDA) at three different temperatures: 613, 633 and 653 K; and 54 kg cm^− 2. The catalytic activities are discussed in relation to the physicochemical properties of the NiMo catalysts, alumina phase and pH of the impregnating solution. The catalytic results show an increase in the conversion profiles with temperature. The sulfur conversion was increased from 89 to 99.25%, 91–99%, 90.8–97%, 83–95% and 78–96% when the crystal size of the support varied from 3 to 20 nm, respectively. The nitrogen and aromatic conversions were also increased in the range of 23–45 wt.%. It was found that the γ phase reached a higher catalytic performance than the η phase. The NiMo catalysts synthesized in a basic medium showed a better catalytic performance than that obtained with those prepared in acid solutions. The significance of the kinetic data to compare the catalysts is discussed. The maximum value of the catalytic activity was reached with the catalysts with the smallest particle sizes.     

HDS and HDN activity of molybdenum and nickel–molybdenum catalysts supported on alumina–titania carriers

Alumina–titania supports containing 5–50 wt.% of TiO₂ were prepared by coprecipitation method using inorganic precursors (sodium aluminate and titanium chloride). DTA-TGA, XRD, SEM, TPD_NH3, and IR spectroscopy were used to characterise these materials. The study shows that the promoting effect of nickel on the HDS activity of molybdenum catalysts supported on Al₂O₃TiO₂ is significantly lower than that for molybdenum catalyst supported on Al₂O₃, and depends on the TiO₂ content. The SEM results show that in the case of rich Al support (20 wt.% of TiO₂) molybdenum was aggregated on the external surface of the catalyst, whereas it was uniformly dispersed on the external surface of alumina. Results also show that molybdenum is preferably supported on aluminum oxide. Application of Al₂O₃TiO₂ oxides enhances the HDN activity of nickel–molybdenum catalysts. The highest HDN efficiency was obtained for the NiMo/Al₂O₃TiO₂ catalyst containing 50 wt.% of TiO₂. HDN activity was found to depend on protonic acidity and anatase content.     

Zr-intercalated molybdenum disulfide: preparation, characterization and catalytic activity in nitrobenzene hydrogenation

Layered composites, Zr-intercalated MoS₂, have been prepared utilizing the exfoliation and restacking properties of Li _x MoS₂ under mild conditions and characterized by X-ray powder diffraction, differential scanning calorimetry and BET surface measurements. It showed the formation of two distinct products depending on the employed Zr:MoS₂ reaction stoichiometry. The interlayer expansions of about 4.4 Å and 9.2 Å suggested mono- or bi-layer arrangements of the hydroxyl–Zr oligocations into the interlayer galleries between the MoS₂ host layers. The composites exhibit good catalytic activities in the hydrogenation of nitrobenzene into aniline, due to their intercalated structures and great specific surface areas.     

油溶性纳米MoS2加氢催化剂的合成、表征和应用

传统MoS₂加氢催化剂粒径大、油溶性差而催化效率相对较低。纳米粒子合成方法很多，其中液相化学合成技术尤其水(溶剂)热、微乳液、单层二硫化钼重堆积和微波液相介电加热法等更为便捷、高效。在油溶性纳米MoS₂的合成中，表面修饰剂的选择最为关键。综述了油溶性纳米MoS₂的合成、表征和应用研究进展，提出了高稳定性、高活性和油溶性纳米MoS₂加氢催化剂高效合成优化参数，为实现工业应用提供了参考。     

Synthesis,characterization and catalytic properties of polypyrrole-supported catalysts

Polypyrrole, a conductive polymer, was used as support of noble metals, namely, copper and palladium, for application in heterogeneous catalysis. Catalysts were characterized by TEM coupled with EDS and XRD. Their activity and selectivity were determined in the reduction of nitrate and intermediate nitrite in water under 1 bar of hydrogen and at room temperature. In nitrite reduction, these novel catalysts demonstrated a better activity and a higher selectivity towards nitrogen formation than their Pd/Al₂O₃ counterpart. On the other hand, the bimetallic catalyst tested for nitrate reduction showed an activity similar to the one of a classical Pd–Cu/Al₂O₃ catalyst, but no intermediate nitrite was observed.     

Synthesis, characterization and cyclohexene hydrogenation activity of high surface area molybdenum disulfide catalysts

An ammonium tetrathiomolybdate (ATTM) catalyst precursor is synthesized and then thermally decomposed at different temperatures in N₂ or H₂ atmosphere. Characterization of the resulting compounds by powder X-ray diffraction (XRD) and surface area analysis indicates the formation of MoS₂–2H with a surface area of 5–9 m²/g. When ATTM is treated with cetyltrimethylammonium chloride and then decomposed in N₂ at 723 K, the resulting material has a surface area nearing 200 m²/g. If treatment also includes hydrazine, the surface area of the resulting MoS₂–2H reaches 215 m²/g. Analysis by XRD and electron microscopy shows a noticeable dispersion in the layers of the resulting MoS₂. The catalytic activity of the materials is tested in a batch reactor for cyclohexene hydrogenation, where the highest activity sulfides are those obtained by thermal decomposition of the chemically treated precursors in N₂.     

Novel phosphorus-doped alumina-supported molybdenum and tungsten carbides: synthesis, characterization and hydrogenation properties

The effect of atomically dispersed phosphorus on Mo₂C- and WC-supported -Al₂O₃ has been studied. Phosphorus was introduced via molybdenum or tungsten heteropolyanions. Mo- and W-based heteropolyanions were used to synthesize supported materials. Propene and tetralin hydrogenation were used as molecular probe reactions to test the activity and selectivity of the alumina-supported molybdenum or tungsten carbides. The effect of phosphorus on the hydrogenation activity of materials was also considered. Catalysts were characterized by X-ray diffraction, transmission electron microscopy (TEM), energy-dispersive spectroscopy (EDS) and CO chemisorption. Phosphorus was found to increase significantly the activity of molybdenum and tungsten carbides. Supported molybdenum carbides are highly dispersed. Tungsten carbide particles are well dispersed with sizes ranging from 2 to 4 nm. To check the stability of carbides they were characterized after catalytic runs.     

负载型非晶态合金的结构及催化加氢性能

采用还原法制备了负载型Ni-B、Ni-P体系非晶态合金催化剂，对其结构进行了物化表征。该方法制备的非晶态合金克服了以往制备方法的非晶态合金比表面积小、热稳定性差的缺点。以甲苯、苯乙烯、苯乙炔、硝基苯、环己酮和己二腈为模型化合物，研究了负载型非晶态合金的催化加氢反应性能，并与多晶Ni催化剂进行对比。结果表明，非晶态合金具有更优越的催化加氢性能，并有可能作为含不同不饱和基团化合物的选择加氢催化剂。     

Structure and catalytic properties of Cu-Ni bimetallic catalysts for hydrogenation

The dependence of catalytic activity and selectivity of Cu-Ni bimetallic catalysts for oil hydrogenation on CuNi ratios have been investigated while they were reduced at low temperature (230 °C). Two maxima occurred at Cu₂Ni₁ and Cu₁Ni₃ in the activity-CuNi curve. Cu riched catalysts have higher selectivity than Ni riched ones, and may cause dehydrogenation and isomerization of linoleate at the beginning of the reaction. The structures of the catalysts reduced at different temperatures have been studied by means of XRD, XPS, EXAFS and FMR et al. The structure of the catalysts reduced at 230 °C can be described as an aggregate of Cu particles inlaid with Ni atoms and unreduced NiO, and the easily reduced Cu always segregates on the surface, while homogeneous solid solution particles can be formed in the case 400 °C being used as reduction temperature.     

磁性纳米负载金属催化剂的制备及其在甲苯催化氢化反应中的性能

通过化学共沉淀法制备了Fe3O4,以硅酸钠、铝酸钠为原料,碳分法原位对其进行表面包覆,制备出具有核壳结构的SiO2/Fe3O4及Al2O3/SiO2/Fe3O4复合磁性纳米粒子。利用XRD、SEM、FTIR以及VSM技术对其进行了表征。将所制备的这两种磁性载体分别负载金属Ru及Ru-Co催化剂,以甲苯为底物考察了负载催化剂的组成与催化加氢活性的关系。结果表明,以SiO2/Fe3O4为载体负载的催化剂具有很好的催化活性,循环使用6次后活性未下降;以Al2O3/SiO2/Fe3O4为载体所负载的催化剂,起始催化活性较高,循环过程中活性略微降低。双金属Ru-Co催化剂的催化性能与其形成的结构及组成密切相关,催化活性为RushellCocoreRu-CoCoshellRucore,Ru/Co的摩尔比为1∶5的RushellCocore/PVP/SiO2/Fe3O4催化剂对甲苯有较高的催化活性,催化剂的转化频率可达16656,高于相同条件下的单金属Ru催化剂的转化频率(9828)。     

Polyaniline–rhodium composites: Preparation,physicochemical characterization,and catalytic properties

In this work, polyaniline (PANI)–rhodium composites have been obtained for the first time. Their preparation procedure has involved reduction of Rh³⁺ ions in RhCl₃ aqueous solutions with NaBH₄ in the presence of PANI. Using UV–vis spectroscopy, it has been found that the reduction process is fast. X‐ray diffraction and Rh3d XPS studies have confirmed that metallic rhodium is incorporated into PANI matrix. SEM and TEM investigations allowed to establish that the sizes of Rh crystallites formed depend on the amount of metal in the composite as well as on the preparation conditions. It has been demonstrated that the composites containing Rh nanoparticles whose size is predominantly below 10 nm can be obtained. IR spectroscopy has proved that PANI chain is protonated in the Rh³⁺ reduction process. Catalytic properties of PANI–Rh composites have been investigated using isopropyl alcohol conversion as the test reaction. It has been found that the composites containing Rh nanoparticles show high redox activity. Catalytic activity of the composites in which larger, agglomerated metal particles have been present is about three times lower. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

国内外加氢转化催化剂的应用和发展趋势

综述了国内外加氢转化催化剂的开发应用现状和发展趋势。尤其对近年来研究开发成功的用于焦化干气、催化干气等含烯烃较高原料的加氢转化催化剂作了较详尽的介绍。     

The electronic structure and catalytic properties of molybdenum sulfides in the coal hydrogenation process

Comparative analysis of the electronic structure of molybdenum sulfides and their catalytic activity in hydrogenation reactions was performed from the results of Hartree-Fock ab initio quantum-chemical calculations using the STO 3-21G* and 6-311G basis sets with geometry optimization. The model reactions of hydrogenation of aromatic and saturated hydrocarbons with hydrogen and hydrogen sulfide were studied. It was shown that the hydrogenation reactions of aromatic hydrocarbons with hydrogen sulfide must occur at a higher rate (with lower activation energy) as compared to those with molecular hydrogen.     

Catalytic properties in hydrogenation and hydrodesulphurization reactions of ruthenium sulphide solid solutions containing iron,cobalt or nickel

Solid solutions M_xRu_1–xS₂ (M = Ni, Co, Fe) were prepared by sulphidation of mixtures of hydroxides at 673 K; their crystallographic properties were studied by X-ray diffraction. These new materials present interesting properties in biphenyl hydrogenation and in thiophene hydrodesulphurization. The catalytic properties are strongly dependent on the nature of the metal associated to ruthenium. Cobalt-ruthenium catalysts present a good activity for hydrodesulphurization but very low activity for hydrogenation, iron catalysts exhibit low activity for both reactions, and nickel catalysts possess remarkable properties in hydrogenation and hydrodesulphurization (twice the activity of pure ruthenium sulphide). A comparison has been established with the properties of molybdenum sulphide catalysts promoted by the same elements.     

Mesoporous Ru/Sn-SBA-15 catalysts: synthesis,characterization and catalytic activity towards hydrogenation of levulinic acid

Journal of Porous Materials - Among the various biomass-derived platform chemicals, levulinic acid (LA) has been identified as one of the top-10 important molecules by Department of Energy, United...     

双金属氰化物络合物催化剂的制备、表征与催化性能研究

分别以PEG-1000、β-环糊精和吐温-60等为助络合剂,采用不同工艺方法制备了具有不同结构的双金属氰化物络合物(DMC)催化剂,研究了不同助络合剂和不同制备方法对DMC催化剂的形貌、粒径、晶型结构和催化活性的影响.结果表明以PEG-1000、β-环糊精和吐温-60等为助络合剂,利用传统制备方法可以获得晶态与非晶态组分混合物的DMC催化剂.而将助络合剂提前加入到钾盐和锌盐溶液中,可制备出高度分散的非晶态的DMC.这种非晶态的DMC催化剂活性高,反应速度快,其催化性能明显优于利用传统制备方法制备的DMC.     

Rhenium,tungsten and molybdenum as substitutes for plantinum in aromatics hydrogenation catalysts

Three metal substitutes for platinum on alumina-supported catalysts have been investigated. These metals are rhenium, tungsten and molybdenum. In the absence of platinum, these metals are catalytically inactive. At high hydrogenation temperatures (≥100°C) rhenium, tungsten and molybdenum appear to substitute platinum up to at least 66.7, 50 and 33.3% of the platinum atoms, respectively, providing almost the same conversion as platinum. At low hydrogenation temperatures (～50°C), the catalyst containing 0.6 wt% Pt is more active than those containing metallic combinations. At low reaction temperatures, in particular for high platinum substitution ratios, tungsten appears functionless whereas molybdenum may act as an inhibitor for platinum.     

Effect of surface composition on the catalytic performance of molybdenum phosphide catalysts in the hydrogenation of acetonitrile

A series of molybdenum phosphide catalysts with initial Mo/P ratios varying in a narrow range of 0.90–1.10 was prepared by temperature-programmed reaction; characterized by X-ray diffraction, BET, elemental analysis, X-ray photoelectron spectroscopy, and CO chemisorption measurements; and tested for the hydrogenation of acetonitrile at different pressures (0.1–1.0 MPa) and temperatures (473–513 K). The catalysts exhibited attractive catalytic activity, especially at a H₂ pressure above 0.2 MPa. The surface composition of the MoP catalysts could be fine-tuned by the initial Mo/P ratio, which consequently led to different surface properties (e.g., CO uptakes) and catalytic behaviors. Catalysts with high initial Mo amount gave high selectivity to the primary amine, ethylamine, whereas those with high initial P amount created more condensed amines, diethylamine and triethylamine.     

Molten salt preparation of stabilized zirconia catalysts : characterization and catalytic properties

Supports of Mo and NiMo catalysts were prepared and tested in hydrotreatment model reactions. These supports, composed of zirconia and various amounts of yttria, were obtained by synthesis in molten salts.

It was found that the distribution of yttrium in zirconium oxide was homogeneous. Moreover, it was shown that the crystalline structure as well as the textural properties (especially the porosity) were stabilized.

These solids were then used as supports of Mo and NiMo sulphides and their activities were compared to those of a commercial NiMo alumina catalyst.

In biphenyl hydrogenation, with the same coverage of Mo (2.8 at/nm²), the activities per gram of both catalysts (supported on zirconia and alumina) were similar, while the activity per atom of Mo of the catalyst supported on ZrO₂---Y₂O₃ was twice the activity of the catalyst supported on alumina.

For NiMo catalysts, a ratio R= Ni/(Ni+Mo)=0.4 with Mo = 2.8 at/nm² and a co-impregnation of the Mo and Ni were required to have a good synergetic effect. The activity per atom of Mo in biphenyl hydrogenation was then enhanced more than twofold when compared to the NiMo/alumina catalyst. In an HDN model reaction (conversion of diethylanyline in the presence of quinoline) the results obtained with zirconia were much better than with alumina.