高分散Ru/Si_(3)N_(4)催化剂的制备及其在CO_(2)加氢中的应用

氮化硅是一种良好的载体,具有较高的水热稳定性和机械稳定性,其表面的氨基基团能够较好地锚定金属,显著提高金属分散度。但是,商品氮化硅比表面积较低,对金属分散作用仍然有限。因此,以自制的高比表面积氮化硅(Si_(3)N_(4))为载体,通过浸渍法制备了不同Ru负载量(质量分数分别为0.5%、1.0%和2.0%)的催化剂(分别为0.5%Ru/Si_(3)N_(4)、1.0%Ru/Si_(3)N_(4)和2.0%Ru/Si_(3)N_(4)),并以商品氮化硅(Si_(3)N_(4)-C)为载体制备了2.0%Ru/Si_(3)N_(4)-C催化剂作为对照组。表征了催化剂的理化性质,测试了其在300℃、0.1 MPa下的CO_(2)加氢反应活性。结果显示,与Si_(3)N_(4)-C相比,Si_(3)N_(4)的比表面积较高(502 m^(2)/g),Si_(3)N_(4)作为载体显著提高了金属分散度,降低了金属粒径,催化剂暴露出更多的活性位点。0.5%Ru/Si_(3)N_(4)的金属粒径较小,展现出强的H_(2)吸附能力,H难以解吸,抑制了中间物种CO加氢生成CH_(4)。随着Ru负载量增加,金属粒径增大,催化剂的CH_(4)选择性更好。Ru/Si_(3)N_(4)系列催化剂中,2.0%Ru/Si_(3)N_(4)的CH_(4)选择性较高(98.8%)。空速为10000 m L/(g·h)时,0.5%Ru/Si_(3)N_(4)的CO选择性为88.2%。与2.0%Ru/Si_(3)N_(4)相比,2.0%Ru/Si_(3)N_(4)-C的金属粒径更大,活性位点较少,活性更低。2.0%Ru/Si_(3)N_(4)和2.0%Ru/Si_(3)N_(4)-C的CO_(2)转化率分别为53.1%和9.2%。Si_(3)N_(4)有效提高了金属分散度,提高了催化剂的CO_(2)加氢反应活性;通过调控Ru负载量控制催化剂金属粒径,可实现对产物CO或CH_(4)选择性的调控。

制备方法对Ru/CeO_(2)催化氨分解性能的影响

采用共沉淀法、沉积沉淀法和浸渍法制备了Ru/CeO_(2)催化剂,利用XRD、N_(2)吸附-脱附、SEM、CO_(2)-TPD、H_(2)-TPD、H_(2)-TPR、XPS、N_(2)-TPD等方法对催化剂进行表征,并考察了催化剂的氨分解性能。实验结果表明,共沉淀法制备的Ru/CeO_(2)-CP催化剂在450℃、气时空速15000 h-1条件下,氨转化率可达80.7%,是沉积沉淀法和浸渍法制备Ru/CeO_(2)催化剂的1.3,2.7倍。共沉淀法制备的催化剂表面疏松,具有最大的比表面积,为催化剂提供了更为丰富的碱性位点。CeO_(2)载体与Ru金属间的强相互作用有利于电子从CeO_(2)向Ru的转移,提高了Ru粒子表面的电子密度,促进了N物种在催化剂表面的结合脱附。

沉淀剂对Ru-Zn催化剂催化苯选择加氢性能的影响

采用共沉淀法制备Ru-Zn催化剂,考察了沉淀剂种类、沉淀pH值对其催化苯选择性加氢性能的影响,并采用N_(2)物理吸附、XRD、SEM、H_(2)-TPR对催化剂进行了表征。结果表明,以NaOH为沉淀剂,沉淀pH=7时制备的Ru-Zn-f催化剂性能较好,苯转化率为40%时,环己烯选择性为82.70%,且该催化剂重复使用5次后,环己烯选择性仍维持在81%以上,稳定性好,具有较好的工业应用前景。

Effect of the graphitic degree of carbon supports on the catalytic performance of ammonia synthesis over Ba-Ru-K/HSGC catalyst

A series of high surface area graphitic carbon materials （HSGCs） were prepared by ball-milling method. Effect of the graphitic degree of HSGCs on the catalytic performance of Ba-Ru-K/HSGC-x （x is the ball-milling time in hour） catalysts was studied using ammonia synthesis as a probe reaction. The graphitic degree and pore structure of HSGC-x supports could be successfully tuned via the variation of ball-milling time. Ru nanoparticles of different Ba-Ru-K/HSGC-x catalysts are homogeneously distributed on the supports with the particle sizes ranging from 1.6 to 2.0 nm. The graphitic degree of the support is closely related to its facile electron transfer capability and so plays an important role in improving the intrinsic catalytic performance of Ba-Ru-K/HSGC-x catalyst.

Inhibiting effect of tungstic compounds on glucose hydrogenation over Ru/C catalyst

The effect of acid component including various conventional acids and tungstic compounds on glucose hydrogenation over a series of binary catalyst system containing Ru/C catalyst was investigated. The results showed that HC1, H2SO4, H3BO3, H3PO4, and HNO3 had negligible effect, while all the tungstic compounds imposed inhibiting effects on the hydrogenation of glucose over Ru/C catalyst, and the suppressing effect followed the order of H2WO4〉HPW〉WO3〉AMT〉HSiW. This order is the same as the order of ethylene glycol （EG） yields in the one-pot conversion of glucose to EG, suggesting the important role of competition between glucose hydrogenation and retro-aldol condensation in controlling the selectivity of EG.

Highly selective CO methanation over amorphous Ni-Ru-B/ZrO_2 catalyst

Amorphous Ni-Ru-B/ZrO2 catalyst was prepared by the means of chemical reduction, and selective CO methanation as a strategy for CO removal in fuel processing applications was investigated over the amorphous Ni-Ru-B/ZrO2 catalyst. The result showed that, at the temperature of 210-230 ℃, the catalyst was shown to be capable of reducing CO in a hydrogen-rich reformate to less than 10 ppm, while keeping the CO2 conversion below 1.55% and the hydrogen consumption below 6.50%. ？2009 Xin Fa Dong. Published by Elsevier B.V. on behalf of Chinese Chemical Society. All rights reserved.

Study on the Nanosized Amorphous Ru-Fe-B/ZrO_2 Alloy Catalyst for Benzene Selective Hydrogenation to Cyclohexene

新奇 nanosized 为到环己烯的苯选择加氢的非结晶的 Ru-Fe-B/ZrO2 合金催化剂被调查。这催化剂的优异性质被归因于 nanosize 和非结晶的特性的联合以及到它的组织上特性。另外，锌离子，在泥浆的 ZrO2 的内容，和催化剂的预告的处理的集中被发现在改进这项活动和催化剂的选择有效。给词调音：Ru-Fe-B/ZrO2 非结晶的催化剂；苯选择加氢；

CO_2 methanation over TiO_2–Al_2O_3 binary oxides supported Ru catalysts

TiO_2 modified Al_2O_3 binary oxide was prepared by a wet-impregnation method and used as the support for ruthenium catalyst. The catalytic performance of Ru/TiO_2–Al_2O_3catalyst in CO_2 methanation reaction was investigated. Compared with Ru/Al_2O_3 catalyst, the Ru/TiO_2–Al_2O_3catalytic system exhibited a much higher activity in CO_2 methanation reaction. The reaction rate over Ru/TiO_2–Al_2O_3 was 0.59 mol CO_2·(g Ru)1·h-1, 3.1 times higher than that on Ru/Al_2O_3[0.19 mol CO_2·(gRu)-1·h-1]. The effect of TiO_2 content and TiO_2–Al_2O_3calcination temperature on catalytic performance was addressed. The corresponding structures of each catalyst were characterized by means of H_2-TPR, XRD, and TEM. Results indicated that the averaged particle size of the Ru on TiO_2–Al_2O_3support is 2.8 nm, smaller than that on Al_2O_3 support of 4.3 nm. Therefore, we conclude that the improved activity over Ru/TiO_2–Al_2O_3catalyst is originated from the smaller particle size of ruthenium resulting from a strong interaction between Ru and the rutile-TiO_2 support, which hindered the aggregation of Ru nanoparticles.

Selective CO methanation over amorphous Ni-Ru-B/ZrO_2 catalyst for hydrogen-rich gas purification

Amorphous Ni-Ru-B/ZrO2 catalysts were prepared by chemical reduction method. The effects of Ni-Ru-B loading and Ru/Ni mole ratio on the catalytic performance for selective CO methanation from reformed fuel were studied, and the catalysts were characterized by BET, ICP, XRD and TPD. The results showed that Ru strongly affected the catalytic activity and selectivity by increasing the thermal stability of amorphous structure, promoting the dispersion of the catalyst particle, and intensifying the CO adsorption. For the catalysts with Ru/Ni mole ratio under 0.15, the CO methanation conversion and selectivity increased significantly with the increasing Ru/Ni mole ratio. Among all the catalysts investigated, the 30 wt% Ni-Ru-B loading amorphous Ni61Ru9B30/ZrO2 catalyst with 0.15 Ru/Ni mole ratio presented the best catalytic performance, over which higher than 99.9% of CO conversion was obtained in the temperature range of 230℃-250℃, and the CO2 conversion was kept under the level of 0.9%.

Effects of Reaction Conditions on Performance of Ru Catalyst and Iron Catalyst for Ammonia Synthesis

激活的支持碳的基于 Ru 的催化剂和 A301 铁催化剂被准备，并且铁催化剂的性能上的反应温度，空间速度，压力，和 H2/N2 比率的影响在系列结合了 Ru 催化剂因为氨合成被调查。活动测试也作为比较在单个 Ru 和 Fe 催化剂上被执行。结果证明为氨合成的 Ru 催化剂的活动比由在反应条件下面的 33.5%37.6%

A Novel Ultrafine Ru-B Amorphous Alloy Catalyst for Glucose Hydrogenation to Sorbitol

An ultrafine Ru-B amorphous alloy catalyst was prepared by chemical reduction with KBH4 in aqueous solution, which exhibited perfect selectivity to sorbitol (~100%) and very high activity during the liquid phase glucose hydrogenation, much higher than the corresponding crystallized Ru-B, the pure Ru powder, and Raney Ni catalysts. The correlation of the catalytic activity to both the structural and surface electronic characteristics was discussed briefly.

Tuned selectivity and enhanced activity of CO_(2) methanation over Ru catalysts by modified metal-carbonate interfaces

Carbonate-modified metal-support interfaces allow Ru/MnCO_(3) catalyst to exhibit over 99% selectivity,great specific activity and long-term anti-CO poisoning stability in atmospheric CO_(2) methanation.As a contrast,Ru/MnO catalyst with metal-oxide interfaces prefers reverse water-gas shift rather than methanation route,along with a remarkably lower activity and a less than 15% CH_(4) selectivity.The carbonatemodified interfaces are found to stabilize the Ru species and activate CO_(2) and H_(2) molecules.Ru-CO^(4) species are identified as the reaction intermediates steadily formed from CO_(2) dissociation,which show moderate adsorption strength and high reactivity in further hydrogenation to CH_(4),Furthermore,carbonates of Ru/MnCO_(3) are found to be consumed by hydrogenation to form CH_(4) and replenished by exchange with CO_(2),which are in a dynamic equilibrium during the reaction.Modification with surface carbonates is proved as an efficient strategy to endow metal-support interfaces of Ru-based catalysts with unique catalytic functions for selective CO_(2) hydrogenation.

Scission of C–O and C–C linkages in lignin over RuRe alloy catalyst

The performance of lignin depolymerization is basically determined by the interunit C–O and C–C bonds.Numerous C–O bond cleavage strategies have been developed, while the cleavage of C–C bond between the primary aromatic units remains a challenging task due to the high dissociation energy of C–C bond.Herein, a multifunctional Ru Re alloy catalyst was designed, which exhibited exceptional catalytic activity for the cleavage of both C–O and C–C linkages in a broad range of lignin model compounds(β-1, a-5, 5–5,β-O-4, 4-O-5) and two stubborn lignins(kraft lignin and alkaline lignin), affording 97.5% overall yield of monocyclic compounds from model compounds and up to 129% of the maximum theoretical yield of monocyclic products based on C–O bonds cleavage from realistic lignin. Scanning transmission electron microscopy(STEM) characterization showed that Ru Re(1:1) alloy particles with hexagonal close-packed structure were homogeneously dispersed on the support. Quasi-in situ X-ray photoelectron spectroscopy(XPS), and X-ray absorption spectroscopy(XAS) indicate that Ru species were predominantly metallic state, whereas Re species were partially oxidized;meanwhile, there was a strong interaction between Ru and Re, where the electron transfer from Re to Ru was occurred, resulting in great improvement on the capability of C–O and C–C bonds cleavage in lignin conversion.

CO selective methanation in hydrogen-rich gas mixtures over carbon nanotube supported Ru-based catalysts

Series of carbon nanotube supported Ru-based catalysts were prepared by impregnation method and applied successfully for complete removal of CO by CO selective methanation from H2-rich gas stream conducted in a fixed-bed quartz tubular reactor at ambient pressure. It was found that the metal promoter, reduction temperature and metal loading affected the catalytic properties significantly. The most excellent performance was presented by 30 wt% Ru-Zr/CNTs catalyst reduced at 350 ℃. Since it decreased CO concentration to below 10 ppm from 12000 ppm by CO selective methanation at the temperature range of 180-240 ℃, and kept CO selectivity higher than 85% at the temperature below 200 ℃. Characterization using XRD, TEM, H2-TPR and XPS suggests that Zr modification of Ru/CNTs results in the weakening of the interaction between Ru and CNTs, a higher Ru dispersion and the oxidization of surface Ru. Amorphous and high dispersed Ru particles with small size were obtained for 30 wt% Ru-Zr/CNTs catalyst reduced at 350 ℃, leading to excellent catalytic performance in CO selective methanation.

Carbon nanotubes-Nafion composites as Pt-Ru catalyst support for methanol electro-oxidation in acid media

Carbon nanotubes-Nafion （CNTs-Nation） composites were prepared by impregnated CNTs with Nation in ethanol solution and characterized by FT-IR. Pt-Ru catalysts supported on CNTs-Nafion composites were synthesized by microwave-assisted polyol process. The physical and electrochemical properties of the catalysts were characterized by X-ray diffraction （XRD）, transmission electron microscope （TEM）, CO stripping voltammetry, cyclic voltammetry （CV） and chronoamperometry （CA）. The results showed that the Nation incorporation in CNTs-Nation composites did not significantly alter the oxygen-containing groups on the CNTs surface. The Pt-Ru catalyst supported on CNTs-Nafion composites with 2 wt% Naton showed good dispersion and the best CO oxidation and methanol electro-oxidation activities.

Solvent effects on Pt-Ru/C catalyst for methanol electro-oxidation

Alloying degree, particle size and the level of dispersion are the key structural parameters of Pt-Ru/C catalyst in fuel cells. Solvent（s） used in the preparation process can affect the particle size and alloying degree of the object substance, which lead to a great positive impact on its properties. In this work, three types of solvents and their mixtures were used in preparation of the Pt-Ru/C catalysts by chemical reduction of metal precursors with sodium borohydride at room temperature. The structure of the catalysts was characterized by X-ray diffraction （XRD） and Transmission electron microscopy （TEM）. The catalytic activity and stability for methanol electro-oxidation were studied by Cyclic Voltammetry （CV） and Chronoamperometry （CA）. Pt-Ru/C catalyst prepared in H2O or binary solvents of H2O and isopropanol had large particle size and low alloying degree leading to low catalytic activity and less stability in methanol electro-oxidation. When tetrahydrofuran was added to the above solvent systems, Pt-Ru/C catalyst prepared had smaller particle size and higher alloying degree which resulted in better catalytic activity, lower onset and peak potentials, compared with the above catalysts. Moreover, the catalyst prepared in ternary solvents of isopropanol, water and tetrahydrofuran had the smallest particle size, and the high alloying degree and the dispersion kept unchanged. Therefore, this kind of catalyst showed the highest catalytic activity and good stability for methanol electro-oxidation.

Carbon dioxide reforming of methane over bimetallic catalysts of Pt-Ru/γ-Al_2O_3 for thermochemical energy storage

The reaction of CO2 reforming of CH4 has been investigated with γ-Al2O3-supported platinum and ruthenium bimetallic catalysts, with the specific purpose of thermochemical energy storage. The catalysts were prepared by using the wetness impregnation method. The prepared catalysts were characterized by a series of physico-chemical characterization techniques such as BET surface area, thermo-gravimetric (TG), transmission electron microscope (TEM) and X-ray photoelectron spectroscopy (XPS). In addition, the amount of carbon deposits on the surface of the catalysts and the type of the carbonaceous species were discussed by TG. It was found that the bimetallic Pt-Ru/γ-Al2O3 catalysts exhibit both superior catalytic activity and remarkable stability by comparison of monometallic catalysts. During the 500 h stability test, the bimetallic catalyst showed a good performance at 800 °C in CO2 reforming of CH4 , exhibiting an excellent anti-carbon performance with the mass loss of less than 8.5%. The results also indicate that CO2 and CH4 have quite stable conversions of 96.0 % and 94.0 %, respectively. Also, the selectivity of the catalysts is excellent with the products ratio of CO/H 2 maintaining at 1.02. Furthermore, it was found in TEM images that the active carbonaceous species were formed during the catalytic reaction, and well-distributed dot-shaped metallic particles with a relatively uniform size of about 3 nm as well as amorphous carbon structures were observed. Combined with BET, TG, TEM tests, it is concluded that the selected bimetallic catalysts can work continuously in a stable state at the high temperature, which has a potential to be utilized for the closed-loop cycle of the solar thermochemical energy storage in future industry applications.

Ru修饰负载型Co基费托合成催化剂性能研究

Ru助剂可以提高Co物种的分散度和还原度,抑制烧结和积炭,进而起到改善Co基催化剂的结构和费托反应催化性能的作用。采用共沉淀法分别制备了不同载体负载的Co基催化剂(Co/MgO、Co/MnO_(2)、Co/NaY、Co/SiO_(2)和Co/ZnO,Co负载量(质量分数,下同)均为30%);再以RuCl_(3)•xH_(2)O为Ru助剂修饰以上Co基催化剂,采用等体积浸渍法分别制得了Ru负载量为0.5%和1.0%的Ru修饰负载型Co基费托合成催化剂。采用N_(2)吸附、XRD和H_(2)-TPR等对催化剂的结构进行了表征,采用固定床反应器评价了催化剂的费托合成催化性能。结果表明,不同负载量的Ru助剂对不同载体负载的Co基催化剂的影响不同。浸渍Ru助剂后,所有催化剂的比表面积和孔容均下降;H_(2)-TPR表征表明Ru助剂能够促进Co物种的还原、降低还原温度,并抑制Co与载体之间难还原物种的生成。Co/MnO_(2)系列催化剂在270℃下才能体现出活性,其中0.5%Ru-Co/MnO_(2)具有最低甲烷选择性(5.45%)和最高C5+选择性(72.83%)。

Immobilized Ruthenium Catalyst for Carbon Dioxide Hydrogenation

Three kinds of cross linked polystyrene resin （PS） supported ruthenium complexes were developed as catalysts for the synthesis of formic acid from carbon dioxide hydrogenation. Many factors, such as the functionalized supports, solvents and ligands, could influence their activities and reuse performances greatly. These immobilized catalysts also offer the industrial advantages such as easy separation.

Reaction mechanism of aqueous-phase conversion of γ-valerolactone(GVL) over a Ru/C catalyst

The present work explores the reaction pathways of γ-valerolactone(GVL) over a supported ruthenium catalyst. The conversion of GVL in aqueous phase over a 5% Ru/C catalyst was investigated in a batch reactor operating at 463 K under 500–1000 psi of H2. The main reaction products obtained under these conditions were 2-butanol(2-BuOH), 1,4-pentanediol(1,4-PDO), 2-methyltetrahydrofuran(2-MTHF) and 2-pentanol(2-PeOH). A complete reaction network was developed, identifying the primary and/or secondary products. In this reaction network, production of 2-BuOH via decarbonylation of a ring-opened surface intermediate CH3CH(O*)–(CH2)2–CO*is clearly the dominant pathway. From the evolution of products as a function of reaction time and theoretical(DFT) calculations, a mechanism for the formation of intermediates and products is proposed. The high sensitivity of 2-BuOH production to the presence of CO, compared to a much lower effect on the production of the other products indicates that the sites responsible for decarbonylation are particularly prone to CO adsorption and poisoning. Also, since the decarbonylation rate is not affected by the H2 pressure it is concluded that the direct decarbonylation path of the CH3CH(O*)–(CH2)2–CO*intermediate does not required a previous dehydrogenation step, as is the case in decarbonylation of short alcohols.