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Sample records for alloy catalysts aided

  1. Catalyst Alloys Processing

    Science.gov (United States)

    Tan, Xincai

    2014-10-01

    Catalysts are one of the key materials used for diamond formation at high pressures. Several such catalyst products have been developed and applied in China and around the world. The catalyst alloy most widely used in China is Ni70Mn25Co5 developed at Changsha Research Institute of Mining and Metallurgy. In this article, detailed techniques for manufacturing such a typical catalyst alloy will be reviewed. The characteristics of the alloy will be described. Detailed processing of the alloy will be presented, including remelting and casting, hot rolling, annealing, surface treatment, cold rolling, blanking, finishing, packaging, and waste treatment. An example use of the catalyst alloy will also be given. Industrial experience shows that for the catalyst alloy products, a vacuum induction remelt furnace can be used for remelting, a metal mold can be used for casting, hot and cold rolling can be used for forming, and acid pickling can be used for metal surface cleaning.

  2. Alloy catalyst material

    DEFF Research Database (Denmark)

    2014-01-01

    The present invention relates to a novel alloy catalyst material for use in the synthesis of hydrogen peroxide from oxygen and hydrogen, or from oxygen and water. The present invention also relates to a cathode and an electrochemical cell comprising the novel catalyst material, and the process use...

  3. Electrodeposited NiCu Alloy Catalysts for Glucose Oxidation

    Energy Technology Data Exchange (ETDEWEB)

    Lim, Jieun; Park, Hansoo; Kim, Sookil [Chung-Ang Univ., Seoul (Korea, Republic of); Ahn, Sang Hyun; Jang, Jong Hyun [Korea Institute of Science and Technology, Seoul (Korea, Republic of)

    2014-07-15

    NiCu alloys have been suggested as potential candidates for catalysts in glucose oxidation. In this study, NiCu alloys with different compositions were prepared on a glassy carbon substrate by changing the electrodeposition potential to examine the effect of Ni/Cu ratios in alloys on catalytic activity toward glucose oxidation. Cyclic voltammetry and chronoamperometry showed that NiCu alloys had higher catalytic activity than pure Ni and Cu catalysts. Especially, Ni{sub 59}Cu{sub 41} had superior catalytic activity, which was about twice that of Ni at a given oxidation potential. X-ray analyses showed that the oxidation state of Ni in NiCu alloys was increased with the content of Cu by lattice expansion. Ni components in alloys with higher oxidation state were more effective in the oxidation of glucose.

  4. Design of a surface alloy catalyst for steam reforming

    DEFF Research Database (Denmark)

    Besenbacher, F.; Chorkendorff, Ib; Clausen, B.S.;

    1998-01-01

    Detailed studies of elementary chemical processes on well-characterized single crystal surfaces have contributed substantially to the understanding of heterogeneous catalysis. insight into the structure of surface alloys combined with an understanding of the relation between the surface composition...... and reactivity is shown to lead directly to new ideas for catalyst design, The feasibility of such an approach is illustrated by the synthesis, characterization, and tests of a high-surface area gold-nickel catalyst for steam reforming....

  5. Furfural Hydrogenation on Alloyed Copper Catalysts With Additives of Ferrosilicium

    Directory of Open Access Journals (Sweden)

    T. K. Akilov

    2015-12-01

    Full Text Available The present work is dedicated to the study of influence of ferrosilicium additives [FA*-ferroalloy containing (% mass: 46.8 Si, ~53,0 Fe, other are (C, P, S impurities] on the activity of alloyed Gu-Al = 50-50 catalyst in the reaction of furfural hydrogenation under hydrogen pressure. Components content varied (% mass: Cu- 40...49, aluminum- 50, FA* -1.0...10.0. The catalysts were prepared from 1g alloys by leaching it with 20% of aqueous solution of caustic soda in boiling water-bath during 1 hour. The phase composition and structure of alloys were investigated by means of roentgenographic and X-ray spectrum methods.

  6. Highly Dispersed Alloy Catalyst for Durability

    Energy Technology Data Exchange (ETDEWEB)

    Murthi, Vivek S.; Izzo, Elise; Bi, Wu; Guerrero, Sandra; Protsailo, Lesia

    2013-01-08

    Achieving DOE's stated 5000-hr durability goal for light-duty vehicles by 2015 will require MEAs with characteristics that are beyond the current state of the art. Significant effort was placed on developing advanced durable cathode catalysts to arrive at the best possible electrode for high performance and durability, as well as developing manufacturing processes that yield significant cost benefit. Accordingly, the overall goal of this project was to develop and construct advanced MEAs that will improve performance and durability while reducing the cost of PEMFC stacks. The project, led by UTC Power, focused on developing new catalysts/supports and integrating them with existing materials (membranes and gas diffusion layers (GDLs)) using state-of-the-art fabrication methods capable of meeting the durability requirements essential for automotive applications. Specifically, the project work aimed to lower platinum group metals (PGM) loading while increasing performance and durability. Appropriate catalysts and MEA configuration were down-selected that protects the membrane, and the layers were tailored to optimize the movements of reactants and product water through the cell to maximize performance while maintaining durability.

  7. Novel Carbon Nanotubes-supported NiB Amorphors Alloy Catalyst for Benzene Hydrogenation

    Institute of Scientific and Technical Information of China (English)

    Mei Hua YANG; Rong Bin ZHANG; Feng Yi LI

    2004-01-01

    The NiB amorphous alloy catalysts supported on CNTs and alumina were prepared by impregnation and chemical reduction. The gas-phase benzene hydrogenation was used as a probe reaction to evaluate the catalytic activity. The result showed that the NiB amorphous alloy catalyst supported on carbon nanotubes exhibited higher activity than that supported on alumina.

  8. Identification of non-precious metal alloy catalysts for selective hydrogenation of acetylene

    DEFF Research Database (Denmark)

    Studt, Felix; Abild-Pedersen, Frank; Bligaard, Thomas

    2008-01-01

    The removal of trace acetylene from ethylene is performed industrially by palladium hydrogenation catalysts ( often modified with silver) that avoid the hydrogenation of ethylene to ethane. In an effort to identify catalysts based on less expensive and more available metals, density functional...... calculations were performed that identified relations in heats of adsorption of hydrocarbon molecules and fragments on metal surfaces. This analysis not only verified the facility of known catalysts but identified nickel- zinc alloys as alternatives. Experimental studies demonstrated that these alloys...

  9. Study of The Pd-B/γ-Al2O3 Amorphous Alloy Catalyst

    Institute of Scientific and Technical Information of China (English)

    2003-01-01

    The Pd-B/γ-Al2O3 amorphous alloy catalyst and Pd/γ-Al2O3 crystalline metal catalyst were prepared by KBH4 reduction and routine impregnation, respectively. Pd-B/γ-A12O3 and Pd/γ-A12O3 catalysts were characterized by XRD and SEM. It was found that the catalytic activity of the Pd-B/γ-A12O3 amorphous alloy catalyst was higher than that of the Pd/γ-A12O3crystalline metal catalyst in the anthraquinone hydrogenation.

  10. Using Mechanical Alloying to Create Bimetallic Catalysts for Vapor-Phase Carbon Nanofiber Synthesis

    Directory of Open Access Journals (Sweden)

    Laura Guevara

    2015-10-01

    Full Text Available Carbon nanofibers were generated over bimetallic catalysts in an atmospheric pressure chemical vapor deposition (APCVD reactor. Catalyst compositions of Fe 30 at%, Cu and Ni 30 at% and Cu were mechanically alloyed using high-energy ball milling over durations of 4, 8, 12, 16, and 20 h. The catalyst powders were then used to produce carbon nanofibers in ethylene and hydrogen (4:1 at temperatures of 500, 550, and 600 °C. The microstructures of the catalysts were characterized as a function of milling time as well as at deposition temperature. The corresponding carbon deposition rates were assessed and are correlated to the microstructural features of each catalyst. The milling process directly determines the performance of each catalyst toward carbon deposition, and both catalysts performed comparably to those made by traditional co-precipitation methods. Considerations in miscible and immiscible nanostructured alloy systems are discussed.

  11. Computational thermodynamics aided design of novel ferritic alloys

    Energy Technology Data Exchange (ETDEWEB)

    Yang, Ying [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Chen, Tianyi [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Tan, Lizhen [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)

    2016-06-30

    With the aid of computational thermodynamics, Ni was identified to suppress the liquidus temperature of Fe2Zr and four Fe-Cr-Ni-Zr alloys were designed to study the Ni effect on the phase stability of Fe2Zr laves_phase. These alloys were fabricated through traditional arc-metling, followed by annealing at 1000 C for 336 hours and 700 C for 1275 hours. The microstructure were examined and characterized by SEM BSE image, EDS compositional mapping and point scan, XRD and TEM analysis. The major results were summarized below: 1)For investigated alloys with 12wt% Cr, 3~6wt% Zr and 3~9 wt%Ni, the phases in equilibrium with the BCC phase are C15_Laves phase, Fe23Zr6 phase. The volume fraction of intermetallic phases increases with Ni and Zr contents. 2)Instead of (Fe,Cr)2Zr C14_Laves phase, Ni stabilizes the C15_Laves structure in Fe-Cr-Ni-Zr alloys by substituting Fe and Cr atoms with Ni atoms in the first sublattice. 3)Fe23Zr6, that is metastable in the Fe-Cr-Zr ternary, is also stabilized by Ni addition. 4)Ni7Zr2 phase was observed in samples with high Ni/Zr ratio. Extensive solubility of Fe was identified in the phase. The microstructural and composition results obtained from this study will be incorportated into the the Fe-Cr-Ni-Zr database. The current samples will be subjected to ion irradiaition to be compared with those results for Fe-Cr-Zr alloys. Additional alloys will be designed to form (Fe,Cr,Ni)2Zr nanoprecipitates for further studies.

  12. Alloyed Ni-Fe nanoparticles as catalysts for NH3 decomposition

    DEFF Research Database (Denmark)

    Simonsen, Søren Bredmose; Chakraborty, Debasish; Chorkendorff, Ib;

    2012-01-01

    A rational design approach was used to develop an alloyed Ni-Fe/Al2O3 catalyst for decomposition of ammonia. The dependence of the catalytic activity is tested as a function of the Ni-to-Fe ratio, the type of Ni-Fe alloy phase, the metal loading and the type of oxide support. In the tests with high...

  13. Metalloporphyrin catalysts for oxygen reduction developed using computer-aided molecular design

    Energy Technology Data Exchange (ETDEWEB)

    Ryba, G.N.; Hobbs, J.D.; Shelnutt, J.A. [and others

    1996-04-01

    The objective of this project is the development of a new class of metalloporphyrin materials used as catalsyts for use in fuel cell applications. The metalloporphyrins are excellent candidates for use as catalysts at both the anode and cathode. The catalysts reduce oxygen in 1 M potassium hydroxide, as well as in 2 M sulfuric acid. Covalent attachment to carbon supports is being investigated. The computer-aided molecular design is an iterative process, in which experimental results feed back into the design of future catalysts.

  14. Miniature fuel cell with monolithically fabricated Si electrodes - Alloy catalyst formation -

    Science.gov (United States)

    Ogura, Daiki; Suzuki, Takahiro; Katayama, Noboru; Dowaki, Kiyoshi; Hayase, Masanori

    2013-12-01

    A novel Pd-Pt catalyst formation process was proposed for reduction of Pt usage. In our miniature fuel cells, porous Pt was used as the catalyst, and the Pt usage was quite high. To reduce the Pt usage, we have attempted to deposit Pt on porous Pd by galvanic replacement, and relatively large output was demonstrated. In this study, in order to reduce more Pt usage and explore the alloy catalyst formation process, atomic layer deposition by UPD-SLRR (Under Potential Deposition - Surface Limited Redox Replacement) was applied to the Pd-Pt catalyst formation. The new process was verified at each process steps by EDS elemental analysis, and the expected spectra were obtained. Prototype cells were constructed by the new process, and cell output was raised to 420mW/cm2 by the Pd-Pt catalyst from 125mW/cm2 with Pd catalyst.

  15. Nanostructured Platinum Alloys for Use as Catalyst Materials

    Science.gov (United States)

    Hays, Charles C. (Inventor); Narayan, Sri R. (Inventor)

    2015-01-01

    A series of binary and ternary Pt-alloys, that promote the important reactions for catalysis at an alloy surface; oxygen reduction, hydrogen oxidation, and hydrogen and oxygen evolution. The first two of these reactions are essential when applying the alloy for use in a PEMFC.

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

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    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.

  17. Amorphous Nickel Based Alloy Catalysts and Magnetically Stabilized Bed Hydrogenation Technology

    Institute of Scientific and Technical Information of China (English)

    MuXuhong; ZongBaoning; 等

    2002-01-01

    Amorphous nickel based alloy catalysts(denoted as the SRNA series catalysts)were prepared via rapid quenching method followed by alkali leaching and other activation procedures.The physicochemical characterizations show that nickel,the active component in these catalysts,exists in the amorphous state,and the catalyst particles possess many nanosized voids leading to large surface area(the highest is 145m2/g).The evaluation results in some model reactions show that the SRNA series catalysts have 2 to 4 times higher activity and selectivity than conventional Raney Ni catalyst for the hydrogenation of compounds with unsatur-ated functional groups.At present,the SRNA series catalysts have been successfully used in hydrogenation of glucose,hydrogenation of pharmaceutical intermediates and purification of caprolactam.In order to use these catalysts efficiently,a magnetically stabilized bed(MSB) technology has been developed by combining the ferromagnetic property of the catalyst with the good mass transfer characteristics of MSB.The demonstration unit of MSB hydrogenation technology has been set up and has kept running for 2800 hours.The results show that,after running 2800 hours,the catalyst still retained good activity; meanwhile,the hydrogenation effi-ciency had been improved 10 times in comparison with the traditional CSTR process.

  18. The AIDS pandemic: a catalyst for women's rights.

    Science.gov (United States)

    Mehta, S

    2006-09-01

    The rates of HIV infection among women are rising at a higher rate than among men. After citing the reasons for women's vulnerability, this report argues the potential role of gynecologists and obstetricians through integration of HIV/AIDS into sexual and reproductive health services to strengthen the response to the epidemic.

  19. Controllable Deposition of Alloy Clusters or Nanoparticles Catalysts on Carbon Surfaces

    Energy Technology Data Exchange (ETDEWEB)

    Sasaki, K.; Ando, Y.; Su, D.; Adzic, R.

    2011-08-15

    We describe a simple method for controllably depositing Pt-Ru alloy nanoparticles on carbon surfaces that is mediated by Pb or Cu adlayers undergoing underpotential deposition and stripping during Pt and Ru codeposition at diffusion-limiting currents. The amount of surface Pt atoms deposited largely reflects the number of potential cycles causing the deposition and stripping of the metal adlayer at underpotentials, the metal species used as a mediator, and the scan rate of the potential cycles. We employed electrochemical methanol oxidation to gain information on the catalyst's activities. The catalysts with large amounts of surface Pt atoms have relatively high methanol-oxidation activity. Catalysts prepared using this method enhance methanol-oxidation activity per electrode surface area, while maintaining catalytic activity per surface Pt atom; thus, the amount of Pt is reduced in comparison with conventional methanol-oxidation catalysts. The method is suitable for efficient synthesizing various bimetallic catalysts.

  20. Amorphous Nickel Based Alloy Catalysts and Magnetically Stabilized Bed Hydrogenation Technology

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    Amorphous nickel based alloy catalysts (denoted as the SRNA series catalysts) were prepared viarapid quenching method followed by alkali leaching and other activation procedures. The physicochemicalcharacterizations show that nickel, the active component in these catalysts, exists in the amorphous state, andthe catalyst particles possess many nanosized voids leading to large surface area (the highest is 145m2/g). Theevaluation results in some model reactions show that the SRNA series catalysts have 2 to 4 times higheractivity and selectivity than conventional Raney Ni catalyst for the hydrogenation of compounds with unsatur-ated functional groups. At present, the SRNA series catalysts have been successfully used in hydrogenation ofglucose, hydrogenation of pharmaceutical intermediates and purification of caprolactam. In order to use thesecatalysts efficiently, a magnetically stabilized bed (MSB) technology has been developed by combining theferromagnetic property of the catalyst with the good mass transfer characteristics of MSB. The demonstrationunit of MSB hydrogenation technology has been set up and has kept running for 2800 hours. The results showthat, after running 2800 hours, the catalyst still retained good activity; meanwhile, the hydrogenation effi-ciency had been improved 10 times in comparison with the traditional CSTR process.

  1. Amorphous Nickel Based Alloy Catalysts and Magnetically Stabilized Bed Hydrogenation Technology

    Institute of Scientific and Technical Information of China (English)

    Mu Xuhong; Zong Baoning; Meng Xiangkun; Min Enze

    2002-01-01

    Amorphous nickel based alloy catalysts (denoted as the SRNAseries catalysts) were prepared viarapid quenching method followed by alkali leaching and other activation procedures. The physicochemicalcharacterizations show that nickel, the active component in these catalysts, exists in the amorphous state, andthe catalyst particles possess many nanosized voids leading to large surface area (the highest is 145m2/g). Theevaluation results in some model reactions show that the SRNA series catalysts have 2 to 4 times higheractivity and selectivity than conventional Raney Ni catalyst for the hydrogenation of compounds with unsatur-ated functional groups. At present, the SRNA series catalysts have been successfully used in hydrogenation ofglucose, hydrogenation of pharmaceutical intermediates and purification of caprolactam. In order to use thesecatalysts efficiently, a magnetically stabilized bed (MSB) technology has been developed by combining theferromagnetic property of the catalyst with the good mass transfer characteristics of MSB. The demonstrationunit of MSB hydrogenation technology has been set up and has kept running for 2800 hours. The results showthat, after running 2800 hours, the catalyst still retained good activity; meanwhile, the hydrogenation effi-ciency had been improved 10 times in comparison with the traditional CSTR process.

  2. Structure, activity, and stability of platinum alloys as catalysts for the oxygen reduction reaction

    DEFF Research Database (Denmark)

    Vej-Hansen, Ulrik Grønbjerg

    In this thesis I present our work on theoretical modelling of platinum alloys as catalysts for the Oxygen Reduction Reaction (ORR). The losses associated with the kinetics of the ORR is the main bottleneck in low-temperature fuel cells for transport applications, and more active catalysts...... are essential for wide-spread use of this technology. platinum alloys have shown great promise as more active catalysts, which are still stable under reaction conditions. We have investigated these systems on multiple scales, using either Density Functional Theory (DFT) or Effective Medium Theory (EMT...... and dealloying due to kinetic barriers, despite the thermodynamic driving force for dissolution. This is followed by our results on trying to decouple the strain and ligand effects for platinum skin structures, and determining whether there is any correlation between adsorption energy and surface stability...

  3. Skeletal Amorphous Nickel Based Alloy Catalysts and Magnetically Stabilized Bed Hydrogenation Technology

    Institute of Scientific and Technical Information of China (English)

    Min Enze

    2004-01-01

    Looking toward 21 century, smaller, cleaner and more energy-efficient technology will be an important trend in the development of chemical industry. In light of the new process requirements,a number of technology breakthroughs have occurred. One of these discoveries, the magnetically stabilized bed (MSB), has been proven a powerful process for intensification. Since its initial research in the late 1980's at Research Institute of Petroleum Processing (RIPP), the MSB technology and related catalytic material have matured rapidly through an intensive research and engineering program, primarily focused on its scaling-up.In this paper, we report the discovery of a novel skeletal amorphous nickel-based alloy and its use in magnetically stabilized bed (MSB). Amorphous alloys are new kinds of catalytic materials with short-range order but long-range disorder structure. In comparison with Raney Ni, the skeletal amorphous nickel-based alloy has an increasingly higher activity in the hydrogenation of reactive groups and compounds including nitro, nitrile, olefin, acetylene, aromatics, etc. Up to now, the amorphous nickel based alloy catalysts, SRNA series catalyst, one with high Ni ratio have been commercially manufactured more than four year. The new SRNA catalyst has been successfully implemented for hydrogenation applications in slurry reactor at Balin Petrochemical, SINOPEC.SRNA catalyst with further improvement in catalytic activity and stability raise its relative stability to 2~4 times of that of conventional catalyst. In the course of the long-cycle operation of SRNA-4 the excellent catalyst activity and stability can bring about such advantage as low reaction temperature, good selectivity and low catalyst resumption.Magnetically stabilized bed (MSB), a fluidized bed of magnetizable particles by applying a spatially uniform and time-invariant magnetic field oriented axially relative to the fluidizing fluid flow, had many advantages such as the low pressure drop and

  4. Pt Monolayer Shell on Nitrided Alloy Core—A Path to Highly Stable Oxygen Reduction Catalyst

    Directory of Open Access Journals (Sweden)

    Jue Hu

    2015-07-01

    Full Text Available The inadequate activity and stability of Pt as a cathode catalyst under the severe operation conditions are the critical problems facing the application of the proton exchange membrane fuel cell (PEMFC. Here we report on a novel route to synthesize highly active and stable oxygen reduction catalysts by depositing Pt monolayer on a nitrided alloy core. The prepared PtMLPdNiN/C catalyst retains 89% of the initial electrochemical surface area after 50,000 cycles between potentials 0.6 and 1.0 V. By correlating electron energy-loss spectroscopy and X-ray absorption spectroscopy analyses with electrochemical measurements, we found that the significant improvement of stability of the PtMLPdNiN/C catalyst is caused by nitrogen doping while reducing the total precious metal loading.

  5. Carbon-supported platinum alloy catalysts for phenol hydrogenation for making industrial chemicals

    Energy Technology Data Exchange (ETDEWEB)

    Srinivas, S.T.; Song, C.

    1999-07-01

    Phenol is available in large quantities in liquids derived from coal and biomass. Phenol hydrogenation is an industrially important reaction to produce cyclohexanone and cyclohexanol. Cyclohexane, cyclohexene and benzene are obtained as minor products in this reaction. Cyclohexanone is an important intermediate in the production of caprolactam for nylon 6 and cyclohexanol for adipic acid production. In USA, cyclohexanol and cyclohexanone are produced by benzene hydrogenation to cyclohexane over nickel or noble metal catalysts, followed by oxidation of cyclohexane to produce a mixture of cyclohexanol and cyclohexanone. Then cyclohexanol is dehydrogenated in the presence of Cu-Zn catalyst to cyclohexanone. Usually phenol hydrogenation is also carried out by using Ni catalyst in liquid phase. However, a direct single-step vapor phase hydrogenation of phenol to give cyclohexanone selectively is more advantageous in terms of energy savings and process economics, since processing is simplified and the endothermic step of cyclohexanol dehydrogenation can be avoided, as demonstrated by Montedipe and Johnson Matthey using promoted Pd/Al{sub 2}O{sub 3} catalyst. While it is not the purpose of this paper to dwell on the relative merits of these routes, it is necessary to mention that while using monometallic catalysts, generally the problem of catalyst deactivation of sintering as well as coking is frequently encountered. Addition and alloying of noble metal (e.g. Pt) with a second metal can result in a catalyst with better selectivity and activity in the reaction which is more resistant to deactivation. This paper presents the results on the single-step vapor phase hydrogenation of phenol over carbon-supported Pt-M (M=Cr, V, Zr) alloy catalysts to yield mainly cyclohexanone or cyclohexanol.

  6. Hierarchical Pd-Sn alloy nanosheet dendrites: an economical and highly active catalyst for ethanol electrooxidation.

    Science.gov (United States)

    Ding, Liang-Xin; Wang, An-Liang; Ou, Yan-Nan; Li, Qi; Guo, Rui; Zhao, Wen-Xia; Tong, Ye-Xiang; Li, Gao-Ren

    2013-01-01

    Hierarchical alloy nanosheet dendrites (ANSDs) are highly favorable for superior catalytic performance and efficient utilization of catalyst because of the special characteristics of alloys, nanosheets, and dendritic nanostructures. In this paper, we demonstrate for the first time a facile and efficient electrodeposition approach for the controllable synthesis of Pd-Sn ANSDs with high surface area. These synthesized Pd-Sn ANSDs exhibit high electrocatalytic activity and superior long-term cycle stability toward ethanol oxidation in alkaline media. The enhanced electrocataytic activity of Pd-Sn ANSDs may be attributed to Pd-Sn alloys, nanosheet dendrite induced promotional effect, large number of active sites on dendrite surface, large surface area, and good electrical contact with the base electrode. Because of the simple implement and high flexibility, the proposed approach can be considered as a general and powerful strategy to synthesize the alloy electrocatalysts with high surface areas and open dendritic nanostructures.

  7. Low-temperature, vapor-liquid-solid, laterally grown silicon films using alloyed catalysts

    Science.gov (United States)

    LeBoeuf, Jerome L.; Brodusch, Nicolas; Gauvin, Raynald; Quitoriano, Nathaniel J.

    2014-12-01

    Using amorphous oxide templates known as micro-crucibles which confine a vapor-liquid-solid catalyst to a specific geometry, two-dimensional silicon thin-films of a single orientation have been grown laterally over an amorphous substrate and defects within crystals have been necked out. The vapor-liquid-solid catalysts consisted nominally of 99% gold with 1% titanium, chromium, or aluminum, and each alloy affected the processing of micro-crucibles and growth within them significantly. It was found that chromium additions inhibited the catalytic effect of the gold catalysts, titanium changed the morphology of the catalyst during processing and aluminum stabilized a potential third phase in the gold-silicon system upon cooling. Two mechanisms for growing undesired nanowires were identified both of which hindered the VLS film growth, fast silane cracking rates and poor gold etching, which left gold nanoparticles near the gold-vapor interface. To reduce the silane cracking rates, growth was done at a lower temperature while an engineered heat and deposition profile helped to reduce NWs caused by the second mechanism. Through experimenting with catalyst compositions, the fundamental mechanisms which produce concentration gradients across the gold-silicon alloy within a given micro-crucible have been proposed. Using the postulated mechanisms, micro-crucibles were designed which promote high-quality, single crystal growth of semiconductors.

  8. Intermetallic Alloys as CO Electroreduction Catalysts-Role of Isolated Active Sites

    DEFF Research Database (Denmark)

    Karamad, Mohammadreza; Tripkovic, Vladimir; Rossmeisl, Jan

    2014-01-01

    binary bulk alloys forming from these elements have been investigated using density functional theory calculations. The electronic and geometric properties of the catalyst surface can be tuned by varying the size of the active centers and the elements forming them. We have identified six different...... potentially selective intermetallic surfaces on which CO can be reduced to methanol at potentials comparable to or even slightly positive than those for CO/CO2 reduction to methane on Cu. Common features shared by most of the selective alloys are single TM sites. The role of single sites is to block parasitic...

  9. Hydrothermal Synthesis of Co-Ru Alloy Particle Catalysts for Hydrogen Generation from Sodium Borohydride

    Directory of Open Access Journals (Sweden)

    Marija Kurtinaitienė

    2013-01-01

    Full Text Available We report the synthesis of μm and sub-μm-sized Co, Ru, and Co-Ru alloy species by hydrothermal approach in the aqueous alkaline solutions (pH ≥ 13 containing CoCl2 and/or RuCl3, sodium citrate, and hydrazine hydrate and a study of their catalytic properties for hydrogen generation by hydrolysis of sodium borohydride solution. This way provides a simple platform for fabrication of the ball-shaped Co-Ru alloy catalysts containing up to 12 wt% Ru. Note that bimetallic Co-Ru alloy bowls containing even 7 at.% Ru have demonstrated catalytic properties that are comparable with the ones of pure Ru particles fabricated by the same method. This result is of great importance in view of the preparation of cost-efficient catalysts for hydrogen generation from borohydrides. The morphology and composition of fabricated catalyst particles have been characterized using scanning electron microscopy, energy dispersive X-ray diffraction, and inductively coupled plasma optical emission spectrometry.

  10. A Novel Carbon Nanotube-Supported NiP Amorphous Alloy Catalyst and Its Hydrogenation Activity

    Institute of Scientific and Technical Information of China (English)

    Yan Ju; Fengyi Li

    2006-01-01

    A carbon nanotube-supported NiP amorphous catalyst (NiP/CNT) was prepared by induced reduction. Benzene hydrogenation was used as a probe reaction for the study of catalytic activity. The effects of the support on the activity and thermal stability of the supported catalyst were discussed based on various characterizations, including XRD, TEM, ICP, XPS, H2-TPD, and DTA. In comparison with the NiP amorphous alloy, the benzene conversion on NiP/CNT catalyst was lower, but the specific activity of NiP/CNT was higher, which is attributed to the dispersion produced by the support, an electron-donating effect, and the hydrogen-storage ability of CNT. The NiP/CNT thermal stability was improved because of the dispersion and electronic effects and the good heat-conduction ability of the CNT support.

  11. Characterization and reactivity of Pd Pt bimetallic supported catalysts obtained by laser vaporization of bulk alloy

    Science.gov (United States)

    Rousset, J. L.; Cadete Santos Aires, F. J.; Bornette, F.; Cattenot, M.; Pellarin, M.; Stievano, L.; Renouprez, A. J.

    2000-09-01

    Bimetallic Pd-Pt clusters produced by laser vaporization of bulk alloy have been deposited on high surface alumina. Energy dispersive X-ray (EDX) analysis and transmission electron microscopy (TEM) show that they have a perfectly well-defined stoichiometry and a narrow range of size. Therefore, they constitute ideal systems to investigate alloying effects towards reactivity. Pd-Pt alloys are already known for their applications in the hydrogenation of unsaturated hydrocarbons, especially aromatics, because this system is highly resistant to sulfur and nitrogen poisoning. In this context, the catalytic properties of this system have been investigated in the hydrogenation of tetralin in the presence of hydrogen sulfide. Preliminary results show that this model catalyst is more sulfur-resistant than each of the pure supported metals prepared by chemical methods.

  12. Magnetically stabilized bed reactor for selective hydrogenation of olefins in reformate with amorphous nickel alloy catalyst

    Institute of Scientific and Technical Information of China (English)

    Xuhong Mu; Enze Min

    2007-01-01

    A magnetically stabilized bed (MSB) reactor for selective hydrogenation of olefins in reformate was developed by combining the advantages of MSB and amorphous nickel alloy catalyst. The effects of operating conditions, such as temperature, pressure, liquid space velocity, hydrogen-to-oil ratio, and magnetic field intensity on the reaction were studied. A mathematical model of MSB reactor for hydrogenation of olefins in reformate was established. A reforming flow scheme with a post-hydrogenation MSB reactor was proposed. Finally, MSB hydrogenation was compared with clay treatment and conventional post-hydrogenation.

  13. The features of CNT growth on catalyst-content amorphous alloy layer by CVD-method

    Science.gov (United States)

    Dubkov, S.; Bulyarskii, S.; Pavlov, A.; Trifonov, A.; Kitsyuk, E.; Mierczynski, P.; Maniecki, T.; Ciesielski, R.; Gavrilov, S.; Gromov, D.

    2016-12-01

    This work is devoted to the CVD-synthesis of arrays of carbon nanotubes (CNTs) on Co-Zr-N-(O), Ni-Nb-N-(O), Co- Ta-N-(O) catalytic alloy films from gas mixture of C2H2+NH3+Ar at a substrate temperature of about 550°C.Heating of the amorphous alloy causes its crystallization and squeezing of the catalytic metal onto the surface. As a result, small catalyst particles are formed on the surface. The CNT growth takes place after wards on these particles. It should be noted that the growth of CNT arrays on these alloys is insensitive to the thickness of alloy film, which makes this approach technically attractive. In particular, the possibility of local CNT growth at the ends of the Co-Ta-N-(O) film and three-level CNT growth at the end of more complex structure SiO2/Ni-Nb-N-O/SiO2/Ni-Nb-N-O/SiO2/Ni-Nb-N-O/SiO2 is demonstrated.

  14. Cavitation-aided grain refinement in aluminium alloys

    NARCIS (Netherlands)

    Atamanenko, T.V.

    2010-01-01

    This thesis deals with grain refinement under the influence of ultrasonic-driven cavitation in aluminium casting processes. Three major goals of this research were: (1) to identify the mechanism of the cavitation-aided grain refinement at different stages of solidification; (2) to reveal the conditi

  15. The Integration of a Structural Water Gas Shift Catalyst with a Vanadium Alloy Hydrogen Transport Device

    Energy Technology Data Exchange (ETDEWEB)

    Barton, Thomas; Argyle, Morris; Popa, Tiberiu

    2009-06-30

    This project is in response to a requirement for a system that combines water gas shift technology with separation technology for coal derived synthesis gas. The justification of such a system would be improved efficiency for the overall hydrogen production. By removing hydrogen from the synthesis gas stream, the water gas shift equilibrium would force more carbon monoxide to carbon dioxide and maximize the total hydrogen produced. Additional benefit would derive from the reduction in capital cost of plant by the removal of one step in the process by integrating water gas shift with the membrane separation device. The answer turns out to be that the integration of hydrogen separation and water gas shift catalysis is possible and desirable. There are no significant roadblocks to that combination of technologies. The problem becomes one of design and selection of materials to optimize, or at least maximize performance of the two integrated steps. A goal of the project was to investigate the effects of alloying elements on the performance of vanadium membranes with respect to hydrogen flux and fabricability. Vanadium was chosen as a compromise between performance and cost. It is clear that the vanadium alloys for this application can be produced, but the approach is not simple and the results inconsistent. For any future contracts, large single batches of alloy would be obtained and rolled with larger facilities to produce the most consistent thin foils possible. Brazing was identified as a very likely choice for sealing the membranes to structural components. As alloying was beneficial to hydrogen transport, it became important to identify where those alloying elements might be detrimental to brazing. Cataloging positive and negative alloying effects was a significant portion of the initial project work on vanadium alloying. A water gas shift catalyst with ceramic like structural characteristics was the second large goal of the project. Alumina was added as a

  16. The Integration of a Structural Water Gas Shift Catalyst with a Vanadium Alloy Hydrogen Transport Device

    Energy Technology Data Exchange (ETDEWEB)

    Barton, Thomas; Argyle, Morris; Popa, Tiberiu

    2009-06-30

    This project is in response to a requirement for a system that combines water gas shift technology with separation technology for coal derived synthesis gas. The justification of such a system would be improved efficiency for the overall hydrogen production. By removing hydrogen from the synthesis gas stream, the water gas shift equilibrium would force more carbon monoxide to carbon dioxide and maximize the total hydrogen produced. Additional benefit would derive from the reduction in capital cost of plant by the removal of one step in the process by integrating water gas shift with the membrane separation device. The answer turns out to be that the integration of hydrogen separation and water gas shift catalysis is possible and desirable. There are no significant roadblocks to that combination of technologies. The problem becomes one of design and selection of materials to optimize, or at least maximize performance of the two integrated steps. A goal of the project was to investigate the effects of alloying elements on the performance of vanadium membranes with respect to hydrogen flux and fabricability. Vanadium was chosen as a compromise between performance and cost. It is clear that the vanadium alloys for this application can be produced, but the approach is not simple and the results inconsistent. For any future contracts, large single batches of alloy would be obtained and rolled with larger facilities to produce the most consistent thin foils possible. Brazing was identified as a very likely choice for sealing the membranes to structural components. As alloying was beneficial to hydrogen transport, it became important to identify where those alloying elements might be detrimental to brazing. Cataloging positive and negative alloying effects was a significant portion of the initial project work on vanadium alloying. A water gas shift catalyst with ceramic like structural characteristics was the second large goal of the project. Alumina was added as a

  17. Ultrasmall PdmMn1-mOx binary alloyed nanoparticles on graphene catalysts for ethanol oxidation in alkaline media

    Science.gov (United States)

    Ahmed, Mohammad Shamsuddin; Park, Dongchul; Jeon, Seungwon

    2016-03-01

    A rare combination of graphene (G)-supported palladium and manganese in mixed-oxides binary alloyed catalysts (BACs) have been synthesized with the addition of Pd and Mn metals in various ratios (G/PdmMn1-mOx) through a facile wet-chemical method and employed as an efficient anode catalyst for ethanol oxidation reaction (EOR) in alkaline fuel cells. The as prepared G/PdmMn1-mOx BACs have been characterized by several instrumental techniques; the transmission electron microscopy images show that the ultrafine alloyed nanoparticles (NPs) are excellently monodispersed onto the G. The Pd and Mn in G/PdmMn1-mOx BACs have been alloyed homogeneously, and Mn presents in mixed-oxidized form that resulted by X-ray diffraction. The electrochemical performances, kinetics and stability of these catalysts toward EOR have been evaluated using cyclic voltammetry in 1 M KOH electrolyte. Among all G/PdmMn1-mOx BACs, the G/Pd0.5Mn0.5Ox catalyst has shown much superior mass activity and incredible stability than that of pure Pd catalysts (G/Pd1Mn0Ox, Pd/C and Pt/C). The well dispersion, ultrafine size of NPs and higher degree of alloying are the key factor for enhanced and stable EOR electrocatalysis on G/Pd0.5Mn0.5Ox.

  18. Bi-Sn alloy catalyst for simultaneous morphology and doping control of silicon nanowires in radial junction solar cells

    Energy Technology Data Exchange (ETDEWEB)

    Yu, Zhongwei [National Laboratory of Solid State Microstructures and School of Electronics Science and Engineering/Collaborative Innovation Center of Advanced Microstructures, Nanjing University, Nanjing 210093 (China); School of Science, Nantong University, Nantong 226000 (China); Lu, Jiawen; Qian, Shengyi; Xu, Jun; Xu, Ling; Wang, Junzhuan; Shi, Yi; Chen, Kunji [National Laboratory of Solid State Microstructures and School of Electronics Science and Engineering/Collaborative Innovation Center of Advanced Microstructures, Nanjing University, Nanjing 210093 (China); Misra, Soumyadeep; Roca i Cabarrocas, Pere [LPICM, CNRS, Ecole Polytechnique, Université Paris-Saclay, 91128 Palaiseau (France); Yu, Linwei, E-mail: yulinwei@nju.edu.cn, E-mail: linwei.yu@polytechnique.edu [National Laboratory of Solid State Microstructures and School of Electronics Science and Engineering/Collaborative Innovation Center of Advanced Microstructures, Nanjing University, Nanjing 210093 (China); LPICM, CNRS, Ecole Polytechnique, Université Paris-Saclay, 91128 Palaiseau (France)

    2015-10-19

    Low-melting point metals such as bismuth (Bi) and tin (Sn) are ideal choices for mediating a low temperature growth of silicon nanowires (SiNWs) for radial junction thin film solar cells. The incorporation of Bi catalyst atoms leads to sufficient n-type doping in the SiNWs core that exempts the use of hazardous dopant gases, while an easy morphology control with pure Bi catalyst has never been demonstrated so far. We here propose a Bi-Sn alloy catalyst strategy to achieve both a beneficial catalyst-doping and an ideal SiNW morphology control. In addition to a potential of further growth temperature reduction, we show that the alloy catalyst can remain quite stable during a vapor-liquid-solid growth, while providing still sufficient n-type catalyst-doping to the SiNWs. Radial junction solar cells constructed over the alloy-catalyzed SiNWs have demonstrated a strongly enhanced photocurrent generation, thanks to optimized nanowire morphology, and largely improved performance compared to the reference samples based on the pure Bi or Sn-catalyzed SiNWs.

  19. Activity and Stability of Rare Earth-Based Hydride Alloys as Catalysts of Hydrogen Absorption-Oxidation Reactions

    Institute of Scientific and Technical Information of China (English)

    Ying Taokai(应桃开); Gao Xueping(高学平); Hu Weikang(胡伟康); Noréus Dag

    2004-01-01

    Rare earth-based AB5-type hydrogen storage alloys as catalysts of hydrogen-diffusion electrodes for hydrogen absorption and oxidation reactions in alkaline fuel cells were investigated. It is demonstrated that the meta-hydride hydrogen-diffusion electrodes could be charged by hydrogen gas and electrochemically discharged at the same time to retain a stable oxidation potential for a long period. The catalytic activities and stability are almost comparable with a Pt catalyst on the active carbon. Further improvement of performances is expected via reduction of catalyst size into nanometers.

  20. Preparation of Uniform Ni-B Amorphous Alloy Catalyst on CNTs and its Performance for Acetylene Selective Hydrogenation

    Institute of Scientific and Technical Information of China (English)

    Chang Yuan HU; Feng Yi LI; Rong Bin ZHANG; Li HUA

    2006-01-01

    Uniform Ni-B amorphous alloys about 14 nm have been prepared on CNTs-A support,named Ni-B/CNTs-A. In comparison with the Ni-B/CNTs amorphous catalyst, Ni-B/CNTs-A showed higher nickel loading, determined by ICP and better catalytic activity and ethylene selectivity in the acetylene hydrogenation reaction.

  1. On the role of reactant transport and (surface) alloy formation for the CO tolerance of carbon supported PtRu polymer electrolyte fuel cell catalysts

    Energy Technology Data Exchange (ETDEWEB)

    Kaiser, J.; Colmenares, L.; Jusys, Z.; Behm, R.J. [Abt. Oberflaechenchemie und Katalyse, Universitaet Ulm (Germany); Moertel, R.; Boennemann, H. [Max-Planck-Institut fuer Kohlenforschung, Muelheim a.d. Ruhr (Germany); Koehl, G.; Modrow, H.; Hormes, J. [Physikalisches Institut, Universitaet Bonn (Germany)

    2006-07-15

    The role of atomic scale intermixing for the electrocatalytic activity of bimetallic PtRu anode catalysts in reformate operated polymer electrolyte fuel cells (PEFC) was investigated, exploiting the specific properties of colloid based catalyst synthesis for the selective preparation of alloyed and non-alloyed bimetallic catalysts. Three different carbon supported PtRu catalysts with different degrees of Pt and Ru intermixing, consisting of (i) carbon supported PtRu alloy particles (PtRu/C), (ii) Pt and Ru particles co-deposited on the same carbon support (Pt+Ru/C), and (iii) a mixture of carbon supported Pt and carbon supported Ru (Pt/C+Ru/C) as well as the respective monometallic Pt/C and Ru/C catalysts were prepared and characterized by electron microscopy (TEM), X-ray absorption spectroscopy, and CO stripping. Their performance as PEFC anode catalysts was evaluated by oxidation of a H{sub 2}/2%CO gas mixture (simulated reformate) under fuel cell relevant conditions (elevated temperature, continuous reaction and controlled reactant transport) in a rotating disk electrode (RDE) set-up. The CO tolerance and H{sub 2} oxidation activity of the three catalysts is comparable and distinctly different from that of the monometallic catalysts. The results indicate significant transport of the reactants, CO{sub ad} and/or OH{sub ad}, between Pt and Ru surface areas and particles for all three catalysts, with only subtle differences from the alloy catalyst to the physical mixture. The high activity and CO tolerance of the bimetallic catalysts, through the formation of bimetallic surfaces, is explained, e.g., by contact formation in nanoparticle agglomerates or by material transport and subsequent surface decoration/surface alloy formation during catalyst preparation, conditioning, and operation. The instability and mobility of the catalysts under these conditions closely resembles concepts in gas phase catalysis. (Abstract Copyright [2006], Wiley Periodicals, Inc.)

  2. Pd-Au bimetallic catalysts: understanding alloy effects from planar models and (supported) nanoparticles.

    Energy Technology Data Exchange (ETDEWEB)

    Gao, Feng; Goodman, Wayne D.

    2012-12-21

    Pd-Au bimetallic catalysts often display enhanced catalytic activities and selectivities compared with Pd-alone catalysts. This enhancement is often caused by two alloy effects, i.e., ensemble and ligand effects. The ensemble effect is dilution of surface Pd by Au. With increasing surface Au coverages, contiguous Pd ensembles disappear and isolated Pd ensembles form. For certain reactions, for example vinyl acetate synthesis, this effect is responsible for reaction rate enhancement via the formation of highly active surface sites, e.g., isolated Pd pairs. The disappearance of contiguous Pd ensembles also switches off side reactions catalyzed by these sites. This explains selectivity increase of certain reactions, for example direct H2O2 synthesis. The ligand effect is electronic perturbation of Au to Pd. By direct charge transfer or affecting bond length, the ligand effect causes the Pd d band to be more filled and the d-band center away from the Fermi level. Both changes make Pd more "atomic like" therefore binding reactants and products weaker. For certain reactions, this eliminates the so-called "self poisoning" and enhances activity/selectivity.

  3. Hydriding/dehydriding properties of NdMgNi alloy with catalyst CeO2

    Institute of Scientific and Technical Information of China (English)

    李霞; 张羊换; 杨泰; 许剑轶; 赵栋梁

    2016-01-01

    Hydrogen storage composites Nd2Mg17-50 wt.%Ni-x wt.%CeO2 (x=0, 0.5, 1.0, 1.5, 2.0) were obtained by induction-ball milling method. The catalytic effect of CeO2 on hydriding kinetics of Nd2Mg17-50 wt.%Ni composite was investigated. X-ray diffrac-tion (XRD) and high resolution transmission electron microscopy (HRTEM), selected area electron diffraction (SAED) analyses showed that Nd2Mg17-50 wt.%Ni alloy had a multiphase structure, consisting of NdMg12, NdMg2Ni, Mg2Ni and Ni phases and the addition of catalyst CeO2 prompted the composites to be partly transformed into amorphous strucutre. The CeO2 improved the maxi-mum hydrogen capacity of Nd2Mg17-50 wt.%Ni alloy from 3.192 wt.% to 3.376 wt.% (x=1.0). What’s more, the increment of diffu-sion coefficientD led to the faster hydriding kinetics, which was calculated by Avrami-Erofeev equation. The dehydrogenation tem-perature reduced from 515.54 to 504.72 K was mainly caused by the decrease of activation energy from 93.28 to 69.36 kJ/mol, which was proved by the Kissinger equation.

  4. PREPARATION AND CHARACTERIZATION OF SPHERICAL PP/PB ALLOYS WITH MgCl2-SUPPORTED ZIEGLER-NATTA CATALYST

    Institute of Scientific and Technical Information of China (English)

    Ai-hua He; Yang-wei Shi; Guo-qing Liu; Wei Yao; Bao-chen Huang

    2012-01-01

    Polypropylene (PP)/polybutene-1 (PB) alloys within reactor were prepared by MgCl2-supported Ziegler-Natta catalyst with sequential two-stage polymerization technology.First,propylene homo-polymerizations were carried out to form isotactic polypropylene (iPP) particles containing active catalyst.Then,butene-1 was subsequently polymerized to form polybutene-1 phase inside the iPP particles.Finally,iPP/PB alloys with spherical shape and adjustable PB content were synthesized.The catalytic activity and catalytic stereospecificity of the Z-N catalyst in the two-stage polymerization process are discussed.The composition and physical properties of the PP alloys were characterized by FT-IR,13C-NMR,SEM,DSC and XRD.It was found that the in-reactor PP alloys are mainly composed of PP and PB with a little amount of poly(buteneco-propylene) random copolymers and poly(butene-block-propylene) block copolymers.SEM measurements verified that the PB phases with size in the range of 300-400 nm dispersed in the PP matrix uniformly.The incorporation of PB upon the PP matrix affects the properties of final products greatly.

  5. Confined-space alloying of nanoparticles for the synthesis of efficient PtNi fuel-cell catalysts.

    Science.gov (United States)

    Baldizzone, Claudio; Mezzavilla, Stefano; Carvalho, Hudson W P; Meier, Josef Christian; Schuppert, Anna K; Heggen, Marc; Galeano, Carolina; Grunwaldt, Jan-Dierk; Schüth, Ferdi; Mayrhofer, Karl J J

    2014-12-15

    The efficiency of polymer electrolyte membrane fuel cells is strongly depending on the electrocatalyst performance, that is, its activity and stability. We have designed a catalyst material that combines both, the high activity for the decisive cathodic oxygen reduction reaction associated with nanoscale Pt alloys, and the excellent durability of an advanced nanostructured support. Owing to the high specific activity and large active surface area, the catalyst shows extraordinary mass activity values of 1.0 A mgPt(-1). Moreover, the material retains its initial active surface area and intrinsic activity during an extended accelerated aging test within the typical operation range. This excellent performance is achieved by confined-space alloying of the nanoparticles in a controlled manner in the pores of the support.

  6. In situ and operando spectroscopic studies of sonically aided catalysts for biogas exhaust abatement

    Science.gov (United States)

    Jodłowski, P. J.; Chlebda, D.; Piwowarczyk, E.; Chrzan, M.; Jędrzejczyk, R. J.; Sitarz, M.; Węgrzynowicz, A.; Kołodziej, A.; Łojewska, J.

    2016-12-01

    The aim of this study was to test sonochemical method to modify surface of catalysts to obtain highly dispersed and active materials for methane combustion. The catalysts were characterised by various physicochemical characterisation methods including: DLS, BET nitrogen adsorption, SEM, EDX and ED-XRF. The results of classical surface analyses and catalytic tests were correlated with the operando DRIFT/MS spectroscopy results. The sonochemical preparation method has proven an efficient way to obtain the active catalysts for methane catalytic combustion. The chromium oxide catalyst has revealed great activity compared to the commercially used palladium catalysts. The DRIFT/MS operando analyses have proven that the formate intermediates at the catalyst surface are stable during methane catalytic combustion.

  7. A microstructural investigation of gas atomized Raney type Al-27.5 at.% Ni catalyst precursor alloys

    Energy Technology Data Exchange (ETDEWEB)

    Mullis, A.M., E-mail: a.m.mullis@leeds.ac.uk [Institute for Materials Research, University of Leeds, Leeds LS2 9JT (United Kingdom); Bigg, T.D., E-mail: t.bigg@leeds.ac.uk [Institute for Materials Research, University of Leeds, Leeds LS2 9JT (United Kingdom); Adkins, N.J., E-mail: n.j.e.adkins@bham.ac.uk [IRC in Materials Processing, University of Birmingham, Edgbaston, Birmingham B15-2TT (United Kingdom)

    2015-11-05

    Quantitative image analysis has been used to investigate the phase composition of gas atomized powders of a Raney type Ni catalyst precursor alloys of composition Al-27.5 at.% Ni in the powder size range 150–212 μm. We find that there are considerable variations in phase composition both between powders from the same batch and as a function distance from the particle surface within individual particles. Such variations may have significant implications for the future production and uptake of such catalysts, including the necessity for post-production crushing of gas atomized powders. Models are proposed to account for both variations. - Highlights: • The phase composition of powder Raney-Ni catalysts has been investigated. • Image analysis is used to quantify differences between and within particles. • Phase composition can vary by up to 10% between the particle surface and centre. • Differences of up to 10% in the mean composition are also found between particles.

  8. Theoretical evaluation of the efficiency of catalysts with the aid of deforming forces

    Energy Technology Data Exchange (ETDEWEB)

    Avakyan, V.G.

    1983-02-10

    The purpose of the present work was to investigate the applicability of deforming forces to the characterization of catalysts and to compare efficiency. A method for calculating the deforming forces appearing as a result of the action of a catalyst on a reactant has been proposed. It has been shown that the magnitudes and directions of the deforming forces correlate with the acceptor properties of the catalyst and can be used for comparing the effects of different catalysts on a reactant. The greater sensitivity of the forces in comparison to the traditional parameters E/sup R//sub AB/ has been demonstrated.

  9. Mechanical alloying of a hydrogenation catalyst used for the remediation of contaminated compounds

    Science.gov (United States)

    Quinn, Jacqueline W. (Inventor); Clausen, Christian A. (Inventor); Geiger, Cherie L. (Inventor); Aitken, Brian S. (Inventor)

    2012-01-01

    A hydrogenation catalyst including a base material coated with a catalytic metal is made using mechanical milling techniques. The hydrogenation catalysts are used as an excellent catalyst for the dehalogenation of contaminated compounds and the remediation of other industrial compounds. Preferably, the hydrogenation catalyst is a bimetallic particle including zero-valent metal particles coated with a catalytic material. The mechanical milling technique is simpler and cheaper than previously used methods for producing hydrogenation catalysts.

  10. Synthesis of graphene through direct decomposition of CO$_2$ with the aid of Ni–Ce–Fe trimetallic catalyst

    Indian Academy of Sciences (India)

    Ghazaleh Allaedini; Siti Masrinda Tasirin; Payam Aminayi

    2016-02-01

    In this study, few-layered graphene (FLG) has been synthesized using the chemical vapour deposition (CVD) method with the aid of a novel Ni–Ce–Fe trimetallic catalyst. Carbon dioxide was used as the carbon source in the present work. The obtained graphene was characterized by Raman spectroscopy, and the results proved that high-quality graphene sheets were obtained. Scanning electron microscopy, atomic force microscopy and transmission electron microscopy pictures were used to investigate the morphology of the prepared FLG. The energydispersive X-ray spectroscopy results confirmed a high yield ($\\sim$48%) of the obtained graphene through this method. Ni–Ce–Fe has been shown to be an active catalyst in the production of high-quality graphene via carbon dioxide decomposition. The X-ray photoelectron spectroscopy spectrum was also obtained to confirm the formation of graphene.

  11. Performance of Pt-Co alloys and CoTPP catalysts for the reduction of oxygen in AFC

    Energy Technology Data Exchange (ETDEWEB)

    Kiros, Y. [Royal Institute of Technology, Stockholm (Sweden); Sampathrajan, A.; Ramanathan, M. [Tamil Nadu Agricultural Univ., Coimbatore (India)

    1996-12-31

    One of the primary problems of the oxygen reduction reaction (ORR) for especially low and medium temperature fuel cells such as AFC, PEFC and PAFC is the high activation overpotential. This high overpotential is due to the complicated nature of the ORR and the morphological properties of the catalyst particles. High catalyst dispersion on the carbon support and small particle sizes, non-agglomeration and/or non-dissolution of the electrocatalyst is desired for the long-term operation of the electrodes. In this study electrodes were tested at different temperatures and concentrations in order to substantiate their influences on the activity and stability of the electrocatalysts, i.e.; cobalt tetraphenylporphyrin (CoTPP) and alloys of platinum and cobalt.

  12. Enhancing the cyclability of Li-O2 batteries using PdM alloy nanoparticles anchored on nitrogen-doped reduced graphene as the cathode catalyst

    Science.gov (United States)

    Leng, Limin; Li, Jing; Zeng, Xiaoyuan; Song, Huiyu; Shu, Ting; Wang, Haishui; Liao, Shijun

    2017-01-01

    An efficient ORR/OER catalyst was developed by anchoring highly dispersed bimetallic PdM (M = Fe, Co, Ni) alloy nanoparticles on nitrogen-doped reduced graphene oxide (N-rGO). This new type of catalyst exhibited excellent ORR/OER activity, and the addition of transition metals also significantly improved catalytic stability, with the catalyst containing Fe (PdFe/N-rGO) exhibiting the best stability. A battery using this PdFe/N-rGO catalyst was capable of long-term stable cycling for 400 cycles (2000 h) with a limited capacity of 1000 mAh g-1 at 400 mA g-1, which was much longer than a battery with Pd/N-rGO as the catalyst (only 80 cycles, 400 h). We attribute the high performance of these catalysts to the high surface area of N-rGO, the anchoring of highly dispersed Pd alloy nanoparticles, and the prevention of Pd alloy nanoparticle aggregation and dissolution by the presence of the transition metals.

  13. AIDS

    Science.gov (United States)

    ... page: //medlineplus.gov/ency/article/000594.htm HIV/AIDS To use the sharing features on this page, ... immunodeficiency virus (HIV) is the virus that causes AIDS. When a person becomes infected with HIV, the ...

  14. Performance of metal alloys as hydrogen evolution reaction catalysts in a microbial electrolysis cell

    NARCIS (Netherlands)

    Jeremiasse, A.W.; Bergsma, J.; Kleijn, J.M.; Saakes, M.; Buisman, C.J.N.; Cohen Stuart, M.A.; Hamelers, H.V.M.

    2011-01-01

    H2 can be produced from organic matter with a microbial electrolysis cell (MEC). To decrease the energy input and increase the H2 production rate of an MEC, a catalyst is used at the cathode. Platinum is an effective catalyst, but its high costs stimulate searching for alternatives, such as non-nobl

  15. Alloyed Ni-Fe nanoparticles as catalysts for NH3 decomposition

    DEFF Research Database (Denmark)

    Simonsen, Søren Bredmose; Chakraborty, Debasish; Chorkendorff, Ib

    2012-01-01

    temperatures and a low NH3-to-H2 ratio, the catalytic activity of the best Ni-Fe/Al2O3 catalyst was found to be comparable or even better to that of a more expensive Ru-based catalyst. Small Ni-Fe nanoparticle sizes are crucial for an optimal overall NH3 conversion because of a structural effect favoring...

  16. Preparation of low-platinum-content platinum-nickel, platinum-cobalt binary alloy and platinum-nickel-cobalt ternary alloy catalysts for oxygen reduction reaction in polymer electrolyte fuel cells

    Science.gov (United States)

    Li, Mu; Lei, Yanhua; Sheng, Nan; Ohtsuka, Toshiaki

    2015-10-01

    A series of low-platinum-content platinum-nickel (Pt-Ni), platinum-cobalt (Pt-Co) binary alloys and platinum-nickel-cobalt (Pt-Ni-Co) ternary alloys electrocatalysts were successfully prepared by a three-step process based on electrodeposition technique and studied as electrocatalysts for oxygen reduction reaction (ORR) in polymer-electrolyte fuel cells. Kinetics of ORR was studied in 0.5 M H2SO4 solution on the Pt-Ni, Pt-Co and Pt-Ni-Co alloys catalysts using rotating disk electrode technique. Both the series of Pt-Ni, Pt-Co binary alloys and the Pt-Ni-Co ternary alloys catalysts exhibited an obvious enhancement of ORR activity in comparison with pure Pt. The significant promotion of ORR activities of Pt-Ni and Pt-Co binary alloys was attributed to the enhancement of the first electron-transfer step, whereas, Pt-Ni-Co ternary alloys presented a more complicated mechanism during the electrocatalysis process but a much more efficient ORR activities than the binary alloys.

  17. Unsupported NiPt alloy metal catalysts prepared by water-in-oil (W/O) microemulsion method for methane cracking

    KAUST Repository

    Zhou, Lu

    2016-05-18

    Unsupported NiPt metal catalyst with Ni/Pt molar ratio of 88/12 is prepared by water-in-oil (W/O) microemulsion method in this study. Compared to monometallic Ni and Pt catalysts, the NiPt catalyst exhibits superior activity and stability for methane cracking. By XRD (X-ray powder diffraction), XPS (X-ray photoelectron spectroscopy) and TEM (Transmission electron microscopy) analyses, the formation of Ni(0)Pt(0) alloy is believed to be the main reason for the reactivity improvement of this catalyst. Carbon nano tube (CNT) with Ni(0)Pt(0) particles anchored on the top of tube are found for the NiPt catalyst. © 2016 Elsevier Ltd.

  18. Catalytic Hydrogenation of Levulinic Acid in Water into g-Valerolactone over Bulk Structure of Inexpensive Intermetallic Ni-Sn Alloy Catalysts

    Directory of Open Access Journals (Sweden)

    Rodiansono Rodiansono

    2015-07-01

    Full Text Available A bulk structure of inexpensive intermetallic nickel-tin (Ni-Sn alloys catalysts demonstrated highly selective in the hydrogenation of levulinic acid in water into g-valerolactone. The intermetallic Ni-Sn catalysts were synthesized via a very simple thermochemical method from non-organometallic precursor at low temperature followed by hydrogen treatment at 673 K for 90 min. The molar ratio of nickel salt and tin salt was varied to obtain the corresponding Ni/Sn ratio of 4.0, 3.0, 2.0, 1.5, and 0.75. The formation of Ni-Sn alloy species was mainly depended on the composition and temperature of H2 treatment. Intermetallics Ni-Sn that contain Ni3Sn, Ni3Sn2, and Ni3Sn4 alloy phases are known to be effective heterogeneous catalysts for levulinic acid hydrogenation giving very excellence g-valerolactone yield of >99% at 433 K, initial H2 pressure of 4.0 MPa within 6 h. The effective hydrogenation was obtained in H2O without the formation of by-product. Intermetallic Ni-Sn(1.5 that contains Ni3Sn2 alloy species demonstrated very stable and reusable catalyst without any significant loss of its selectivity. © 2015 BCREC UNDIP. All rights reserved. Received: 26th February 2015; Revised: 16th April 2015; Accepted: 22nd April 2015  How to Cite: Rodiansono, R., Astuti, M.D., Ghofur, A., Sembiring, K.C. (2015. Catalytic Hydrogenation of Levulinic Acid in Water into g-Valerolactone over Bulk Structure of Inexpensive Intermetallic Ni-Sn Alloy Catalysts. Bulletin of Chemical Reaction Engineering & Catalysis, 10 (2: 192-200. (doi:10.9767/bcrec.10.2.8284.192-200Permalink/DOI: http://dx.doi.org/10.9767/bcrec.10.2.8284.192-200  

  19. Development of Ultra-Low Platinum Alloy Cathode Catalysts for PEM Fuel Cells

    Energy Technology Data Exchange (ETDEWEB)

    Popov, Branko N. [Univ. of South Carolina, Columbia, SC (United States). Dept. of Chemical Engineering; Weidner, John [Univ. of South Carolina, Columbia, SC (United States)

    2016-01-07

    The goal of this project is to synthesize a low cost PEM fuel cell cathode catalyst and support with optimized average mass activity, stability of mass activity, initial high current density performance under H2/air (power density), and catalyst and support stability able to meet 2017 DOE targets for electrocatalysts for transportation applications. Pt*/ACCS-2 catalyst was synthesized according to a novel methodology developed at USC through: (i) surface modification, (ii) metal catalyzed pyrolysis and (iii) chemical leaching to remove excess meal used to dope the support. Pt* stands for suppressed platinum catalyst synthesized with Co doped platinum. The procedure results in increasing carbon graphitization, inclusion of cobalt in the bulk and formation of non-metallic active sites on the carbon surface. Catalytic activity of the support shows an onset potential of 0.86 V for the oxygen reduction reaction (ORR) with well-defined kinetic and mass transfer regions and 2.5% H2O2 production. Pt*/ACCS-2 catalyst durability under 0.6-1.0 V potential cycling and support stability under 1.0-1.5 V potential cycling was evaluated. The results indicated excellent catalyst and support performance under simulated start-up/shut down operating conditions (1.0 – 1.5 V, 5000 cycles) which satisfy DOE 2017 catalyst and support durability and activity. The 30% Pt*/ACCS-2 catalyst showed high initial mass activity of 0.34 A/mgPGM at 0.9 ViR-free and loss of mass activity of 45% after 30,000 cycles (0.6-1.0 V). The catalyst performance under H2-air fuel cell operating conditions showed only 24 mV (iR-free) loss at 0.8 A/cm2 with an ECSA loss of 42% after 30,000 cycles (0.6-1.0 V). The support stability under 1.0-1.5 V potential cycling showed mass activity loss of 50% and potential loss of 8 mV (iR-free) at 1.5 A/cm2. The ECSA loss was 22% after 5,000 cycles. Furthermore, the Pt*/ACCS-2 catalyst showed an

  20. CFD aided optimization of an innovative SCR catalyst design for heavy-duty marine diesel engines

    Science.gov (United States)

    Krastev, V. K.; Russo, S.; Verdemare, D.; Recine, G.; Biferale, L.; Falcucci, G.

    2016-06-01

    In this paper, the design of a new system for reducing NOx from exhaust gases from marine engines is shown. The core of the system is represented by the Selective Catalytic Reduction (SCR) reactor, in which the catalyst is made of titanium dioxide nano-fibers functionalized with metal oxides and deposited by electrospinning on a corrugated metal support. Compared to the current monolithic reactor designs, the high specific surface offered by the fibers allows in principle to satisfy the TIER III emission standards, with a consistent saving in the reactor volume. To optimize the reactor design process, a Computational Fluid Dynamics (CFD) model has been developed, alongside experimental measurements and numerical simulations. Results of different configurations are reported and critically assessed.

  1. L-S mass transfer in G-L-S countercurrent magnetically stabilized bed with amorphous alloy SRNA-4 catalyst

    Institute of Scientific and Technical Information of China (English)

    Wei; Li; Baoning; Zong; Xiaofang; Li; Xiangkun; Meng; Jinli; Zhang

    2007-01-01

    Liquid-solid (L-S) mass transfer coefficients (Ks) were characterized in a gas-liquid-solid (G-L-S) three-phase countercurrent magnetically stabilized bed (MSB) using amorphous alloy SRNA-4 as the solid phase. Effects of superficial liquid velocity, superficial gas velocity, magnetic field strength, liquid viscosity and surface tension were investigated. Experimental results indicated that the external magnetic field increased Ks in three-phase MSB, as compared to those in conventional G-L-S fluidized beds; that Ks increased with magnetic field strength, superficial gas and liquid velocities and decreased with liquid viscosity and surface tension; and that Ks showed uniform axial and radial distributions except for small increases close to the wall. Dimensionless correlations were established to estimate Ks of the G-L-S countercurrent MSB using SRNA-4catalyst, with an average error of 3.6%.

  2. Hydrogenation of furfuryl alcohol to tetrahydrofurfuryl alcohol on NiB/SiO2 amorphous alloy catalyst

    Institute of Scientific and Technical Information of China (English)

    SONG Yun; LI Wei; ZHANG Minghui; TAO Keyi

    2007-01-01

    NiB/SiO2 amorphous alloy catalyst was prepared by power electroless plating method and characterized by induction coupled plasma (ICP),Brunauer-Emmett-Teller method (BET),transmission electron microscope (TEM)and X-ray diffraction (XRD) techniques.The catalytic performance of NiB/SiO2 was investigated for the hydrogenation of furfuryl alcohol (FA) to tetrahydrofurfuryl alcohol (THFA).The effects of operational conditions,such as reaction temperature,pressure,and stirring rate were carefully studied.The proper conditions were determined as the following:pressure 2.0 MPa,temperature 120℃ and stirring rate 550 r/min.A typical result with FA conversion of 99%and THFA selectivity of 100% was obtained under such conditions,which was close to that over Raney Ni.

  3. Catalytic activity of Pd-doped Cu nanoparticles for hydrogenation as a single-atom-alloy catalyst.

    Science.gov (United States)

    Cao, Xinrui; Fu, Qiang; Luo, Yi

    2014-05-14

    The single atom alloy of extended surfaces is known to provide remarkably enhanced catalytic performance toward heterogeneous hydrogenation. Here we demonstrate from first principles calculations that this approach can be extended to nanostructures, such as bimetallic nanoparticles. The catalytic properties of the single-Pd-doped Cu55 nanoparticles have been systemically examined for H2 dissociation as well as H atom adsorption and diffusion, following the concept of single atom alloy. It is found that doping a single Pd atom at the edge site of the Cu55 shell can considerably reduce the activation energy of H2 dissociation, while the single Pd atom doped at the top site or in the inner layers is much less effective. The H atom adsorption on Cu55 is slightly stronger than that on the Cu(111) surface; however, a larger nanoparticle that contains 147 atoms could effectively recover the weak binding of the H atoms. We have also investigated the H atom diffusion on the 55-atom nanoparticle and found that spillover of the produced H atoms could be a feasible process due to the low diffusion barriers. Our results have demonstrated that facile H2 dissociation and weak H atom adsorption could be combined at the nanoscale. Moreover, the effects of doping one more Pd atom on the H2 dissociation and H atom adsorption have also been investigated. We have found that both the doping Pd atoms in the most stable configuration could independently exhibit their catalytic activity, behaving as two single-atom-alloy catalysts.

  4. Effect of Ni, Fe and Fe-Ni alloy catalysts on the synthesis of metal contained carbon nano-onions and studies of their electrochemical hydrogen storage properties

    Institute of Scientific and Technical Information of China (English)

    Chenguang Zhang; Jiajun Li; Chunsheng Shi; Chunnian He; Enzuo Liu; Naiqin Zhao

    2014-01-01

    Three types of carbon nano-onions (CNOs) including Ni@CNOs, Fe3C@CNOs and Fe0.64Ni0.36@CNOs nanoparticles have been synthesized by catalytic decomposition of methane at 850◦C using nickel, iron and iron-nickel alloy catalysts. Comparative and systematic studies have been carried out on the morphology, structural characteristics and graphitic crystallinity of these CNOs products. Furthermore, the electro-chemical hydrogen storage properties of three types of CNOs have been investigated. Measurements show that the Ni@CNOs have the highest discharge capacity of 387.2 mAh/g, corresponding to a hydrogen storage of 1.42%. This comparison study shows the advantages of each catalyst in the growth of CNOs, enabling the controllable synthesis and tuning the properties of CNOs by mediating different metals and their alloy for using in the fuel cell system.

  5. Nitrogen-doped graphene/CoNi alloy encased within bamboo-like carbon nanotube hybrids as cathode catalysts in microbial fuel cells

    Science.gov (United States)

    Hou, Yang; Yuan, Heyang; Wen, Zhenhai; Cui, Shumao; Guo, Xiaoru; He, Zhen; Chen, Junhong

    2016-03-01

    Cost-effective catalysts are of key importance to the successful deployment of microbial fuel cells (MFCs) for electricity generation from organic wastes. Herein, a novel catalyst prepared by one-step synthesis strategy is reported. The catalyst features N-doped bamboo-like carbon nanotube (BCNT) in which CoNi-alloy is encapsulated at the end and/or the middle section of the tube with many graphene layers inside inner cavities of BCNT (N-G@CoNi/BCNT). The prepared N-G@CoNi/BCNT exhibits a high oxygen reduction reaction (ORR) activity with an early onset potential of 0.06 V vs. Ag/AgCl and a comparable exchange current density to that of commercial Pt/C. The excellent catalytic activity is further evidenced by a high electron transfer number of 3.63. When being applied in MFCs, the N-G@CoNi/BCNT yields an average current density of 6.7 A m-2, slightly lower than that of Pt/C but with a less mass transfer potential loss. The cost of the N-G@CoNi/BCNT for constructing a 1-m2 cathode electrode is 200 times lower than that of Pt/C. With such a competitive price and excellent electrocatalytic-activity resulting from its unique morphology, CoNi-alloy/nitrogen dopants, considerable specific surface area, and carbon-coated alloy/graphene hybridization, the present catalyst is a promising candidate for ORR catalysts in MFCs for energy recovery from wastes.

  6. Computational Modeling aided Near Net Shape Manufacturing for Aluminum Alloys Project

    Data.gov (United States)

    National Aeronautics and Space Administration — This program will focus on developing and validating computational models for near-net shape processing of aluminum alloys. Computational models will be developed...

  7. Combined high-pressure cell-ultrahigh vacuum system for fast testing of model metal alloy catalysts using scanning mass spectrometry

    DEFF Research Database (Denmark)

    Johansson, Martin; Jørgensen, Jan Hoffmann; Chorkendorff, Ib

    2004-01-01

    An apparatus for fabrication, surface analysis in ultrahigh vacuum, and testing of the catalytic activity of model metal alloy catalysts is described. Arrays of model catalysts are produced by electron-beam deposition of up to four metals simultaneously onto a substrate. The surface analysis...... techniques available are scanning electron microscopy, x-ray photoemission spectroscopy, ion scattering spectroscopy, Auger electron spectroscopy, sputter profiling, and temperature programmed desorption. The catalytic activity of the model catalysts is tested individually by scanning a combined gas delivery...... be studied on a substrate 10 mm in diameter. A high pressure cell with an all-metal sealed ultrahigh vacuum lock is also described as part of the work. ©2004 American Institute of Physics....

  8. A Platinum Monolayer Core-Shell Catalyst with a Ternary Alloy Nanoparticle Core and Enhanced Stability for the Oxygen Reduction Reaction

    Directory of Open Access Journals (Sweden)

    Haoxiong Nan

    2015-01-01

    Full Text Available We synthesize a platinum monolayer core-shell catalyst with a ternary alloy nanoparticle core of Pd, Ir, and Ni. A Pt monolayer is deposited on carbon-supported PdIrNi nanoparticles using an underpotential deposition method, in which a copper monolayer is applied to the ternary nanoparticles; this is followed by the galvanic displacement of Cu with Pt to generate a Pt monolayer on the surface of the core. The core-shell Pd1Ir1Ni2@Pt/C catalyst exhibits excellent oxygen reduction reaction activity, yielding a mass activity significantly higher than that of Pt monolayer catalysts containing PdIr or PdNi nanoparticles as cores and four times higher than that of a commercial Pt/C electrocatalyst. In 0.1 M HClO4, the half-wave potential reaches 0.91 V, about 30 mV higher than that of Pt/C. We verify the structure and composition of the carbon-supported PdIrNi nanoparticles using X-ray powder diffraction, X-ray photoelectron spectroscopy, thermogravimetry, transmission electron microscopy, and energy dispersive X-ray spectrometry, and we perform a stability test that confirms the excellent stability of our core-shell catalyst. We suggest that the porous structure resulting from the dissolution of Ni in the alloy nanoparticles may be the main reason for the catalyst’s enhanced performance.

  9. Formation and Characterization of Pd, Pt and Pd-Pt Alloy Films on Polyimide by Catalyst-Enhanced Chemical Vapor Deposition

    Institute of Scientific and Technical Information of China (English)

    ZHOU Jinlan; CHENG Yinhua; Yousuf Hamadan; YU Kaichao

    2007-01-01

    Platinum, palladium and their alloy films on polyimide were formed by catalyst-enhanced chemical vapor deposition (CVD) in the carrier gas (N2, O2) at 220-300 ℃ under reduced pressure and normal pressure. The deposition of palladium complexes [ Pd((η3-allyl)(hfac) and Pd(hfac)2 ] gives pure palladium film,while the deposition of platinum needs the enhancement of palladium complex by mixing precursor platinum complex Pt(COD)Me2 and palladium complex in the same chamber. The co-deposition of Pd and Pt metals was used for the deposition of alloy films. During the CVD of palladium-platinum alloy, the Pd/Pt atomic ratios vary under different co-deposition conditions. These metal films were characterized by XPS and SEM, and show a good adhesive property.

  10. Alternative alloys for catalysts and platinum jewelry? New structures in Pt-Hf and Pt-Mo

    Science.gov (United States)

    Gilmartin, Erin; Corbitt, Jacqueline; Hart, Gus

    2009-03-01

    The only known intermetallic structure with an 8:1 stoichiometry is that of Pt8Ti. It is intriguing that an ordered phase would occur at such low concentrations of the minority atom, but this structure occurs in about a dozen binary intermetallic systems. The formation of an ordered phase in an alloy can significantly enhance the performance of the material, particularly the hardness. We have taken a broad look at possible systems where this phase forms. Using first-principles, we calculated the stability of this structure relative to experimentally known phases for more than 80 Pt/Pd binary systems. We find the Pt8Ti structure is a possible ground state in more than 20 cases. Our experimental collaborators have verified our prediction in Pt-Mo and observed order-hardening in Pt-Hf. We discuss the discovery of new ground states that are likely to be verified experimentally and their impact on materials for Pt- and Pd-based catalysts and jewelry.

  11. CuAu–ZnO–graphene nanocomposite: A novel graphene-based bimetallic alloy-semiconductor catalyst with its enhanced photocatalytic degradation performance

    Energy Technology Data Exchange (ETDEWEB)

    Xie, Hong [College of Chemistry and Chemical Engineering, Lanzhou University, Lanzhou 730000 (China); Ye, Xiaoliang [College of Chemistry and Chemical Engineering, Lanzhou University, Lanzhou 730000 (China); College of Chemistry and Chemical Engineering, Xiamen University, Xiamen 361005 (China); Duan, Kaiyue; Xue, Muyin; Du, Yongling; Ye, Weichun [College of Chemistry and Chemical Engineering, Lanzhou University, Lanzhou 730000 (China); Wang, Chunming, E-mail: wangcm@lzu.edu.cn [College of Chemistry and Chemical Engineering, Lanzhou University, Lanzhou 730000 (China)

    2015-07-05

    Graphical abstract: In this work, we have successfully synthesized a novel graphene-based bimetallic alloy-semiconductor catalyst: CuAu–ZnO–Gr nanocomposite, and which behaved an enhanced photocatalytic activity. - Highlights: • A bimetallic alloy-based catalyst: CuAu–ZnO–Gr is synthesized. • CuAu–ZnO–Gr behaves an enhanced photocatalytic activity. • The detailed explanation of photocatalytic mechanism of CuAu–ZnO–Gr. - Abstract: The bimetallic alloy CuAu nanoparticles (NPs) can produce more photogenerated electrons when compared with single metal Au NPs. Moreover, graphene (Gr) sheets can help the charge separation and slow down the recombination of the electron hole pairs of ZnO. Hence, a novel graphene-based bimetallic alloy-semiconductor catalyst: CuAu–ZnO–Gr nanocomposite is synthesized. Due to the synergistic effect among CuAu NPs, ZnO nanopyramids, and Gr sheets, CuAu–ZnO–Gr behaves an enhanced photocatalytic activity for the photocatalytic degradation of synthetic colorants methyl orange (MO), methylene blue (MB), indigotin (IN), sunset yellow (SY), and tartrazine (TT) under the simulated sunlight irradiation. Furthermore, the apparent rate constants (k{sub app}) of MO, MB, IN, SY, and TT degradation are estimated respectively. In addition, the as-prepared CuAu–ZnO–Gr nanocomposite is characterized by X-ray diffraction, UV–vis spectrum, transmission electron microscopy, energy dispersive X-ray analysis (EDX), and EDX mapping. As a result of the facile synthesis route and the enhanced photocatalytic activity, this new material CuAu–ZnO–Gr can be a promising photocatalyst for the degradation of dyes.

  12. Fracture performance of computer-aided manufactured zirconia and alloy crowns

    NARCIS (Netherlands)

    Rosentritt, M.; Behr, M.; Thaller, C.; Rudolph, H.; Feilzer, A.J.

    2009-01-01

    Objective: To compare the fracture resistance and fracture performance of CAD/CAM zirconia and alloy crowns. Method and Materials: One electrophoretic deposition alumina ceramic (Wolceram, Wolceram) and 4 zirconia-based systems (ce.novation, ce.novation; Cercon, DeguDent; Digizon, Amann Girrbach; an

  13. Laser-Aided Direct Writing of Nickel-Based Single-Crystal Super Alloy (N5)

    Science.gov (United States)

    Wang, Yichen; Choi, Jeongyoung; Mazumder, Jyoti

    2016-12-01

    This communication reports direct writing of René N5 nickel-based Super alloy. N5 powder was deposited on (100) single-crystal substrate of René N5, for epitaxial growth, using laser and induction heating with a specially designed closed-loop thermal control system. A thin wall (1 mm width) of René N5 single crystal of 22.1 mm (including 3 mm SX substrate) in height was successfully deposited within 100 layers. SEM and EBSD characterized the single-crystal nature of the deposit.

  14. Nanostructured Fe(III) catalysts for water oxidation assembled with the aid of organic acid salt electrolytes

    Science.gov (United States)

    Zhao, Qiang; Li, Dandan; Gao, Guofeng; Yuan, Wen; Hao, Genyan; Li, Jinping

    2016-11-01

    We describe the preparation of three partially ordered iron-based catalyst films (Fe-OAc, Fe-Pro, Fe-But) with nanoporous structure by electrodeposition from organate electrolytes containing Fe2+. The anions of the organic acids assisted the partial ordering of the nanostructured Fe(III) catalysts for water oxidation. A model involving an electrical double layer is invoked to explain the role of the organate electrolyte system in their formation. Analytical results have revealed the main component of the iron-based films to be a β-FeOOH structure. The Fe-But catalyst catalyzed water oxidation in 0.1 m potassium carbonate solution with an average activity of 1.48 mA cm-2 and an overpotential of 433 mV.

  15. A new application of photocatalysts: synthesis of nano-sized metal and alloy catalysts by a photo-assisted deposition method.

    Science.gov (United States)

    Mori, Kohsuke; Araki, Takashi; Takasaki, Tomoya; Shironita, Sayoko; Yamashita, Hiromi

    2009-05-01

    Supported Pd catalysts were synthesized using various semiconductor materials by a photo-assisted deposition method under UV-light irradiation. The Pd precursor was deposited and partially reduced by the direct interaction with the photo-excited state of the semiconductor materials, and subsequently transformed into metal particles by H(2) reduction. CO adsorption and Pd K-edge XAFS measurements demonstrated that the mean diameter of the deposited Pd particles can be controlled by the type of employed semiconductor materials. The catalytic activities in the direct synthesis of hydrogen peroxide (H(2)O(2)) using H(2) and O(2) gases under atmospheric pressure were strongly dependent on the type of supports. Here, the use of TiO(2) comprising a mixed phase of anatase and rutile was the most efficient based on the amount of Pd. The photo-assisted deposition also provides a simple and straightforward method to synthesize PdAu alloy nanoparticles. For the structural model of PdAu nanoparticles, we suggest that most of the Au atoms are preferentially located in the core region, whereas the Pd atoms are preferentially located in the shell region. The PdAu/TiO(2) catalysts prepared by the photo-assisted deposition method were shown to perform significantly better than the pure Pd/TiO(2) catalysts.

  16. Alloy

    Science.gov (United States)

    Cabeza, Sandra; Garcés, Gerardo; Pérez, Pablo; Adeva, Paloma

    2014-07-01

    The Mg98.5Gd1Zn0.5 alloy produced by a powder metallurgy route was studied and compared with the same alloy produced by extrusion of ingots. Atomized powders were cold compacted and extruded at 623 K and 673 K (350 °C and 400 °C). The microstructure of extruded materials was characterized by α-Mg grains, and Mg3Gd and 14H-LPSO particles located at grain boundaries. Grain size decreased from 6.8 μm in the extruded ingot, down to 1.6 μm for powders extruded at 623 K (350 °C). Grain refinement resulted in an increase in mechanical properties at room and high temperatures. Moreover, at high temperatures the PM alloy showed superplasticity at high strain rates, with elongations to failure up to 700 pct.

  17. Microstructure formation and interface characteristics of directionally solidified TiAl-Si alloys in alumina crucibles with a new Y2O3 skull-aided technology

    Science.gov (United States)

    Fan, Jianglei; Liu, Jianxiu; Wu, Shen; Tian, Shuxia; Gao, Hongxia; Wang, Shengyong; Guo, Jingjie; Wang, Xiao

    2017-03-01

    The microstructure evolution and interface characteristics of a directionally solidified Ti-43Al-3Si (at.%) alloy in an alumina (Al2O3) crucible with new Y2O3 skull-aided technology were investigated. The Y2O3-skull that is in contact with the TiAl-melt is relatively stable, which results in a more controlled reaction between the skull and the melt than in the case of an Al2O3 crucible is used. A thin reaction layer was formed between the mould and the melt through mutual diffusion. The layer thickness increased with increasing reaction time. The thickness of this layer was less than 80 μm for reaction times up to 5800 s. Y2O3 particles were not found in the specimen because the mould coating was prepared with fine Y2O3 powder without a binder, which prevented the Y2O3 particles splitting from the coating as a consequence of thermal physical erosion. The oxygen content of the TiAl-alloy increased with increasing reaction time. The total oxygen content of the solidified specimen was less than that of the specimen solidified in the Al2O3 crucibles. This new Y2O3 skull-aided technology is expected to improve the surface quality of TiAl-alloys and reduce the reaction between the crucible/mould and molten TiAl alloys during directional solidification processing with longer contact times.

  18. Quantification of zinc atoms in a surface alloy on copper in an industrial-type methanol synthesis catalyst

    DEFF Research Database (Denmark)

    Kuld, Sebastian; Moses, Poul Georg; Sehested, Jens;

    2014-01-01

    Methanol has recently attracted renewed interest because of its potential importance as a solar fuel.1 Methanol is also an important bulk chemical that is most efficiently formed over the industrial Cu/ZnO/Al2O3 catalyst. The identity of the active site and, in particular, the role of ZnO...... as a promoter for this type of catalyst is still under intense debate.2 Structural changes that are strongly dependent on the pretreatment method have now been observed for an industrial-type methanol synthesis catalyst. A combination of chemisorption, reaction, and spectroscopic techniques provides...

  19. Quantification of zinc atoms in a surface alloy on copper in an industrial-type methanol synthesis catalyst

    DEFF Research Database (Denmark)

    Kuld, Sebastian; Moses, Poul Georg; Sehested, Jens;

    2014-01-01

    Methanol has recently attracted renewed interest because of its potential importance as a solar fuel. Methanol is also an important bulk chemical that is most efficiently formed over the industrial Cu/ZnO/Al2O3 catalyst. The identity of the active site and, in particular, the role of ZnO...... as a promoter for this type of catalyst is still under intense debate. Structural changes that are strongly dependent on the pretreatment method have now been observed for an industrial-type methanol synthesis catalyst. A combination of chemisorption, reaction, and spectroscopic techniques provides a consistent...

  20. Families as catalysts for peer adherence support in enhancing hope for people living with HIV/AIDS in South Africa

    Directory of Open Access Journals (Sweden)

    Caroline Masquillier

    2014-04-01

    Full Text Available Introduction: Hope is an essential dimension of successful coping in the context of illnesses such as HIV/AIDS, because positive expectations for the future alleviate emotional distress, enhance quality of life and have been linked to the capacity for behavioural change. The social environment (e.g. family, peers is a regulator of hope for people living with HIV/AIDS (PLWHA. In this regard, the dual aim of this article is (1 to analyze the influence of a peer adherence support (PAS intervention and the family environment on the state of hope in PLWHA and (2 to investigate the interrelationship between the two determinants. Methods: The Effective AIDS Treatment and Support in the Free State study is a prospective randomized controlled trial. Participants were recruited from 12 public antiretroviral treatment (ART clinics across five districts in the Free State Province of South Africa. Each of these patients was assigned to one of the following groups: a control group receiving standard care, a group receiving additional biweekly PAS or a group receiving PAS and nutritional support. Latent cross-lagged modelling (Mplus was used to analyse the impact of PAS and the family environment on the level of hope in PLWHA. Results: The results of the study indicate that neither PAS nor the family environment has a direct effect on the level of hope in PLWHA. Subsequent analysis reveals a positive significant interaction between family functioning and PAS at the second follow-up, indicating that better family functioning increases the positive effect of PAS on the state of hope in PLWHA. Conclusions: The interplay between well-functioning families and external PAS generates higher levels of hope, which is an essential dimension in the success of lifelong treatment. This study provides additional insight into the important role played by family dynamics in HIV/AIDS care, and it underscores the need for PAS interventions that are sensitive to the contexts in

  1. Widely tunable alloy composition and crystal structure in catalyst-free InGaAs nanowire arrays grown by selective area molecular beam epitaxy

    Energy Technology Data Exchange (ETDEWEB)

    Treu, J., E-mail: Julian.Treu@wsi.tum.de, E-mail: Gregor.Koblmueller@wsi.tum.de; Speckbacher, M.; Saller, K.; Morkötter, S.; Xu, X.; Riedl, H.; Abstreiter, G.; Finley, J. J.; Koblmüller, G., E-mail: Julian.Treu@wsi.tum.de, E-mail: Gregor.Koblmueller@wsi.tum.de [Walter Schottky Institut, Physik Department, Center of Nanotechnology and Nanomaterials, Technische Universität München, Am Coulombwall 4, Garching 85748 (Germany); Döblinger, M. [Department of Chemistry, Ludwig-Maximilians-Universität München, Butenandtstr. 5-13, Munich 81377 (Germany)

    2016-02-01

    We delineate the optimized growth parameter space for high-uniformity catalyst-free InGaAs nanowire (NW) arrays on Si over nearly the entire alloy compositional range using selective area molecular beam epitaxy. Under the required high group-V fluxes and V/III ratios, the respective growth windows shift to higher growth temperatures as the Ga-content x(Ga) is tuned from In-rich to Ga-rich InGaAs NWs. Using correlated x-ray diffraction, transmission electron microscopy, and micro-photoluminescence spectroscopy, we identify structural defects to govern luminescence linewidths in In-rich (x(Ga) < 0.4) and Ga-rich (x(Ga) > 0.6) NWs, whereas limitations at intermediate Ga-content (0.4 < x(Ga) < 0.6) are mainly due to compositional inhomogeneities. Most remarkably, the catalyst-free InGaAs NWs exhibit a characteristic transition in crystal structure from wurtzite to zincblende (ZB) dominated phase near x(Ga) ∼ 0.4 that is further reflected in a cross-over from blue-shifted to red-shifted photoluminescence emission relative to the band edge emission of the bulk ZB InGaAs phase.

  2. Correlation between diffusion barriers and alloying energy in binary alloys

    DEFF Research Database (Denmark)

    Vej-Hansen, Ulrik Grønbjerg; Rossmeisl, Jan; Stephens, Ifan;

    2016-01-01

    In this paper, we explore the notion that a negative alloying energy may act as a descriptor for long term stability of Pt-alloys as cathode catalysts in low temperature fuel cells.......In this paper, we explore the notion that a negative alloying energy may act as a descriptor for long term stability of Pt-alloys as cathode catalysts in low temperature fuel cells....

  3. Computer-Aided Design of Manufacturing Chain Based on Closed Die Forging for Hardly Deformable Cu-Based Alloys

    Science.gov (United States)

    Pietrzyk, Maciej; Kuziak, Roman; Pidvysots'kyy, Valeriy; Nowak, Jarosław; Węglarczyk, Stanisław; Drozdowski, Krzysztof

    2013-07-01

    Two copper-based alloys were considered, Cu-1 pct Cr and Cu-0.7 pct Cr-1 pct Si-2 pct Ni. The thermal, electrical, and mechanical properties of these alloys are given in the paper and compared to pure copper and steel. The role of aging and precipitation kinetics in hardening of the alloys is discussed based upon the developed model. Results of plastometric tests performed at various temperatures and various strain rates are presented. The effect of the initial microstructure on the flow stress was investigated. Rheologic models for the alloys were developed. A finite element (FE) model based on the Norton-Hoff visco-plastic flow rule was applied to the simulation of forging of the alloys. Analysis of the die wear for various processes of hot and cold forging is presented as well. A microstructure evolution model was implemented into the FE code, and the microstructure and mechanical properties of final products were predicted. Various variants of the manufacturing cycles were considered. These include different preheating schedules, hot forging, cold forging, and aging. All variants were simulated using the FE method and loads, die filling, tool wear, and mechanical properties of products were predicted. Three variants giving the best combination of forging parameters were selected and industrial trials were performed. The best manufacturing technology for the copper-based alloys is proposed.

  4. Oxidation catalyst

    Science.gov (United States)

    Ceyer, Sylvia T.; Lahr, David L.

    2010-11-09

    The present invention generally relates to catalyst systems and methods for oxidation of carbon monoxide. The invention involves catalyst compositions which may be advantageously altered by, for example, modification of the catalyst surface to enhance catalyst performance. Catalyst systems of the present invention may be capable of performing the oxidation of carbon monoxide at relatively lower temperatures (e.g., 200 K and below) and at relatively higher reaction rates than known catalysts. Additionally, catalyst systems disclosed herein may be substantially lower in cost than current commercial catalysts. Such catalyst systems may be useful in, for example, catalytic converters, fuel cells, sensors, and the like.

  5. High-performance core-shell PdPt@Pt/C catalysts via decorating PdPt alloy cores with Pt

    Science.gov (United States)

    Wu, Yan-Ni; Liao, Shi-Jun; Liang, Zhen-Xing; Yang, Li-Jun; Wang, Rong-Fang

    A core-shell structured low-Pt catalyst, PdPt@Pt/C, with high performance towards both methanol anodic oxidation and oxygen cathodic reduction, as well as in a single hydrogen/air fuel cell, is prepared by a novel two-step colloidal approach. For the anodic oxidation of methanol, the catalyst shows three times higher activity than commercial Tanaka 50 wt% Pt/C catalyst; furthermore, the ratio of forward current I f to backward current I b is high up to 1.04, whereas for general platinum catalysts the ratio is only ca. 0.70, indicating that this PdPt@Pt/C catalyst has high activity towards methanol anodic oxidation and good tolerance to the intermediates of methanol oxidation. The catalyst is characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), and X-ray photoelectron spectroscopy (XPS). The core-shell structure of the catalyst is revealed by XRD and TEM, and is also supported by underpotential deposition of hydrogen (UPDH). The high performance of the PdPt@Pt/C catalyst may make it a promising and competitive low-Pt catalyst for hydrogen fueled polymer electrolyte membrane fuel cell (PEMFC) or direct methanol fuel cell (DMFC) applications.

  6. 通过Au修饰提高质子交换膜燃料电池PtCo合金催化剂稳定性%Improved Stability of PtCo Alloy Catalysts for Proton Exchange Membrane Fuel Cells by Gold Decoration

    Institute of Scientific and Technical Information of China (English)

    陈磊; 齐意; 木士春

    2015-01-01

    目的:解决质子交换膜燃料电池贵金属催化剂利用率低、电化学稳定性差的问题,从而堆动其产业化进程。方法通过湿化学共沉积法获得低Pt特征的PtCo合金催化剂,采用欠电位沉积方法制备Au修饰的PtCo合金催化剂,应用原子吸收光谱和电化学循环伏安加速测试技术研究Au修饰PtCo合金催化剂的电化学稳定性。结果成功制备了Au修饰的PtCo合金催化剂。 Au修饰后,PtCo合金催化剂的氧还原反应性能几乎没有改变,但Co的溶蚀率得到降低,而且电化学稳定性也得到提高。结论通过采用Au等具有高电化学腐蚀电位的金属修饰Pt合金催化剂,以提高催化剂电化学稳定性的研究思路是可行的。%ABSTRACT:Objective To facilitate the commercialization of proton exchange membrane fuel cells by revolving the key issues in-cluding low utilization and deteriorated stability of noble metal catalysts. Methods After preparation of PtCo alloy catalysts with low Pt loading by a chemical co-deposition method, the gold decorated PtCo alloy catalyst was prepared in terms of an under-potential-deposition method, and then the electrochemical stability of the gold-decorated PtCo alloy catalyst was characterized by atomic ab-sorption spectroscopy and electrochemical accelerated test technique. Results Au-decorated PtCo alloy catalyst was successfully prepared. After decoration of gold, the oxygen reduction reaction activity of PtCo alloy catalysts remained unchanged, and the ero-sion rate of Co element for PtCo alloy catalysts in electrolyte solutions decreased with an improved electrochemical stability. Con-clusion It was feasible to improve the stability of PtCo alloy catalysts by decoration with metals possessing a high corrosion potential such as Au.

  7. High-Activity Dealloyed Catalysts

    Energy Technology Data Exchange (ETDEWEB)

    Kongkanand, Anusorn [General Motors LLC, Pontiac, MI (United States)

    2014-09-30

    Reduction of costly Pt usage in proton exchange membrane fuel cell electrodes is one of the major challenges towards development and commercialization of fuel cell vehicles. Although few have met the initial-kinetic activity requirements in a realistic fuel cell device, no catalyst material has ever met the demanding fuel cell durability targets set by DOE. In this project, a team of 4 universities and 2 companies came together to investigate a concept that appeared promising in preliminary non-fuel cell tests then to further develop the catalyst to a mature level ready for vehicle implementation. The team consists of academia with technical leadership in their respective areas, a catalyst supplier, and a fuel cell system integrator.The tightly collaborative project enabled development of a highly active and durable catalyst with performance that significantly exceeds that of previous catalysts and meets the DOE targets for the first time (Figure 1A). The catalyst was then further evaluated in full-active-area stack in a realistic vehicle operating condition (Figure 1B). This is the first public demonstration that one can realize the performance benefit and Pt cost reduction over a conventional pure Pt catalyst in a long-term realistic PEMFC system. Furthermore, systematic analyses of a range of catalysts with different performance after fuel cell testing allowed for correlation between catalyst microstructure and its electrocatalytic activity and durability. This will in turn aid future catalyst development.

  8. Supported bimetallic nano-alloys as highly active catalysts for the one-pot tandem synthesis of imines and secondary amines from nitrobenzene and alcohols

    NARCIS (Netherlands)

    Meenakshisundaram, Sankar; He, Qian; Dawson, Simon; Nowicka, Ewa; Lu, Li; Bruijnincx, Pieter C. A.; Beale, Andrew M.; Kiely, Christopher J.; Weckhuysen, Bert M.

    2016-01-01

    The synthesis and functionalization of imines and amines are key steps in the preparation of many fine chemicals and for pharmaceuticals in particular. Traditionally, metal complexes are used as homogeneous catalysts for these organic transformations. Here we report gold-palladium and ruthenium-pall

  9. CO methanation over supported bimetallic Ni-Fe catalysts: From computational studies towards catalyst optimization

    DEFF Research Database (Denmark)

    Kustov, Arkadii; Frey, Anne Mette; Larsen, Kasper Emil

    2007-01-01

    DFT calculations combined with a computational screening method have previously shown that bimetallic Ni-Fe alloys should be more active than the traditional Ni-based catalyst for CO methanation. That was confirmed experimentally for a number of bimetallic Ni-Fe catalysts supported on MgAl2O4. He...

  10. Catalyst and electrode research for phosphoric acid fuel cells

    Science.gov (United States)

    Antoine, A. C.; King, R. B.

    1987-01-01

    An account is given of the development status of phosphoric acid fuel cells' high performance catalyst and electrode materials. Binary alloys have been identified which outperform the baseline platinum catalyst; it has also become apparent that pressurized operation is required to reach the desired efficiencies, calling in turn for the use of graphitized carbon blacks in the role of catalyst supports. Efforts to improve cell performance and reduce catalyst costs have led to the investigation of a class of organometallic cathode catalysts represented by the tetraazaannulenes, and a mixed catalyst which is a mixture of carbons catalyzed with an organometallic and a noble metal.

  11. Electrochemical Characteristics of LaNi4.5Al0.5 Alloy Used as Anodic Catalyst in a Direct Borohydride Fuel Cell

    Institute of Scientific and Technical Information of China (English)

    Lianbang Wang; Guobin Wu; Zhenzhen Yang; Yunfang Gao; Xinbiao Mao; Chun'an Ma

    2011-01-01

    Fuel cells using borohydride as the fuel have received much attention because of high energy density and theoretical working potential. In this work, LaNi4.5Al0.5 hydrogen storage alloy used as the anodic material has been investigated. It was found that the increasing; operation temperature was helpful to the open-circuit potential, the discharge potential and the power density, but showed a negative effect on the utilization of the fuel due to the accelerated hydrogen evolution. The high KOH concentration was favorable for high-rate discharge capability. The adsorption and transformation of hydrogen on LaNi4.5Al0.5 alloy electrode has been observed, but its contribution to the discharge capability during a high-rate discharge was small.

  12. Homogeneous catalysts

    CERN Document Server

    Chadwick, John C; Freixa, Zoraida; van Leeuwen, Piet W N M

    2011-01-01

    This first book to illuminate this important aspect of chemical synthesis improves the lifetime of catalysts, thus reducing material and saving energy, costs and waste.The international panel of expert authors describes the studies that have been conducted concerning the way homogeneous catalysts decompose, and the differences between homogeneous and heterogeneous catalysts. The result is a ready reference for organic, catalytic, polymer and complex chemists, as well as those working in industry and with/on organometallics.

  13. Rhenium Nanochemistry for Catalyst Preparation

    Directory of Open Access Journals (Sweden)

    Vadim G. Kessler

    2012-08-01

    Full Text Available The review presents synthetic approaches to modern rhenium-based catalysts. Creation of an active center is considered as a process of obtaining a nanoparticle or a molecule, immobilized within a matrix of the substrate. Selective chemical routes to preparation of particles of rhenium alloys, rhenium oxides and the molecules of alkyltrioxorhenium, and their insertion into porous structure of zeolites, ordered mesoporous MCM matrices, anodic mesoporous alumina, and porous transition metal oxides are considered. Structure-property relationships are traced for these catalysts in relation to such processes as alkylation and isomerization, olefin metathesis, selective oxidation of olefins, methanol to formaldehyde conversion, etc.

  14. Manufacture of Catalyst Systems for Ammonia Conversion

    Institute of Scientific and Technical Information of China (English)

    GAKH S.V.; SAVENKOV D.A.

    2012-01-01

    Platinum catalyst gauzes have been in use since the moment of development of the process of catalyst oxidation of ammonia for production of nitric acid or hydrocyanic acid.Catalyst gauzes are usually made of platinum or its alloys with rhodium and palladium.These precious metals have remarkable properties that make them ideal catalysts for acceleration of the ammonia/oxygen reaction.In 2008,OJSC "SIC ‘Supermetal’" and Umicore AG&Co.KG launched a production line for Pt-alloy-based catalyst systems to be used for ammonia oxidation in the production of weak nitric acid.Catalyst systems consist of a pack of catalyst gauzes and a pack of catchment gauzes,which are made using flat-bed knitting machines and wire-cloth looms.Today,up-to-date catalyst systems MKSpreciseTM are being manufactured,the basic advantages of which are an individual structure of gauzes and composition of the material,which allows to define precisely the position of each gauze in the catalyst pack,a high activity of the catalyst pack,direct catching of platinum and rhodium in the catalyst system,and a reasonable combination of single- and multilayer types of gauzes.This makes it possible to vary the configuration of the catalyst and select an optimum composition of the system to ensure the maximum efficiency of the ammonia oxidation process.We also produce the catchment systems that allow to find the best decision from the economic point view for each individual case.

  15. Catalyst mixtures

    Energy Technology Data Exchange (ETDEWEB)

    Masel, Richard I.; Rosen, Brian A.

    2017-02-14

    Catalysts that include at least one catalytically active element and one helper catalyst can be used to increase the rate or lower the overpotential of chemical reactions. The helper catalyst can simultaneously act as a director molecule, suppressing undesired reactions and thus increasing selectivity toward the desired reaction. These catalysts can be useful for a variety of chemical reactions including, in particular, the electrochemical conversion of CO.sub.2 or formic acid. The catalysts can also suppress H.sub.2 evolution, permitting electrochemical cell operation at potentials below RHE. Chemical processes and devices using the catalysts are also disclosed, including processes to produce CO, OH.sup.-, HCO.sup.-, H.sub.2CO, (HCO.sub.2).sup.-, H.sub.2CO.sub.2, CH.sub.3OH, CH.sub.4, C.sub.2H.sub.4, CH.sub.3CH.sub.2OH, CH.sub.3COO.sup.-, CH.sub.3COOH, C.sub.2H.sub.6, O.sub.2, H.sub.2, (COOH).sub.2, or (COO.sup.-).sub.2, and a specific device, namely, a CO.sub.2 sensor.

  16. Photo-oxidation catalysts

    Science.gov (United States)

    Pitts, J. Roland; Liu, Ping; Smith, R. Davis

    2009-07-14

    Photo-oxidation catalysts and methods for cleaning a metal-based catalyst are disclosed. An exemplary catalyst system implementing a photo-oxidation catalyst may comprise a metal-based catalyst, and a photo-oxidation catalyst for cleaning the metal-based catalyst in the presence of light. The exposure to light enables the photo-oxidation catalyst to substantially oxidize absorbed contaminants and reduce accumulation of the contaminants on the metal-based catalyst. Applications are also disclosed.

  17. Synthesis and characterization of mesoporous hydrocracking catalysts

    Science.gov (United States)

    Munir, D.; Usman, M. R.

    2016-08-01

    Mesoporous catalysts have shown great prospective for catalytic reactions due to their high surface area that aids better distribution of impregnated metal. They have been found to contain more adsorption sites and controlled pore diameter. Hydrocracking, in the presence of mesoporous catalyst is considered more efficient and higher conversion of larger molecules is observed as compared to the cracking reactions in smaller microporous cavities of traditional zeolites. In the present study, a number of silica-alumina based mesoporous catalysts are synthesized in the laboratory. The concentration and type of surfactants and quantities of silica and alumina sources are the variables studied in the preparation of catalyst supports. The supports prepared are well characterized using SEM, EDX, and N2-BET techniques. Finally, the catalysts are tested in a high pressure autoclave reactor to study the activity and selectivity of the catalysts for the hydrocracking of a model mixture of plastics comprising of LDPE, HDPE, PP, and PS.

  18. Discovery of technical methanation catalysts based on computational screening

    DEFF Research Database (Denmark)

    Sehested, Jens; Larsen, Kasper Emil; Kustov, Arkadii

    2007-01-01

    Methanation is a classical reaction in heterogeneous catalysis and significant effort has been put into improving the industrially preferred nickel-based catalysts. Recently, a computational screening study showed that nickel-iron alloys should be more active than the pure nickel catalyst...

  19. Catalysts for Efficient Production of Carbon Nanotubes

    Science.gov (United States)

    Sun, Ted X.; Dong, Yi

    2009-01-01

    Several metal alloys have shown promise as improved catalysts for catalytic thermal decomposition of hydrocarbon gases to produce carbon nanotubes (CNTs). Heretofore almost every experiment on the production of carbon nanotubes by this method has involved the use of iron, nickel, or cobalt as the catalyst. However, the catalytic-conversion efficiencies of these metals have been observed to be limited. The identification of better catalysts is part of a continuing program to develop means of mass production of high-quality carbon nanotubes at costs lower than those achieved thus far (as much as $100/g for purified multi-wall CNTs or $1,000/g for single-wall CNTs in year 2002). The main effort thus far in this program has been the design and implementation of a process tailored specifically for high-throughput screening of alloys for catalyzing the growth of CNTs. The process includes an integral combination of (1) formulation of libraries of catalysts, (2) synthesis of CNTs from decomposition of ethylene on powders of the alloys in a pyrolytic chemical-vapor-decomposition reactor, and (3) scanning- electron-microscope screening of the CNTs thus synthesized to evaluate the catalytic efficiencies of the alloys. Information gained in this process is put into a database and analyzed to identify promising alloy compositions, which are to be subjected to further evaluation in a subsequent round of testing. Some of these alloys have been found to catalyze the formation of carbon nano tubes from ethylene at temperatures as low as 350 to 400 C. In contrast, the temperatures typically required for prior catalysts range from 550 to 750 C.

  20. Highly dispersed metal catalyst

    Energy Technology Data Exchange (ETDEWEB)

    Xiao, Xin; West, William L.; Rhodes, William D.

    2016-11-08

    A supported catalyst having an atomic level single atom structure is provided such that substantially all the catalyst is available for catalytic function. A process of forming a single atom catalyst unto a porous catalyst support is also provided.

  1. 用于质子交换膜燃料电池的高活性、高稳定性PtIrFe/C三元合金催化剂∗%Remarkably Active and Durable PtIrFe/C Ternary Alloy Catalysts with Potential Application to Proton Exchange Membrane Fuel Cells

    Institute of Scientific and Technical Information of China (English)

    杜鑫鑫; 王晓霞; 贺阳; 王健农

    2016-01-01

    采用催化裂解法制备了多孔碳,将其作为催化剂载体,利用液相还原和真空热处理工艺制备出PtIrFe/C三元合金催化剂。采用 X射线衍射、透射电子显微镜等手段对样品的结构形貌进行表征。使用电化学测试手段研究了不同热处理温度对其催化性能的影响。实验结果表明,热处理带来的合金化作用使催化剂的催化活性和耐久性得到了极大的提高。经过700℃热处理的样品,其面积比活性和质量比活性分别是传统商业 Pt/C 催化剂的3~4倍。%Using a mesoporous carbon (prepared via catalyzed pyrolysis)as a support material,PtIrFe/C alloy catalysts were synthesized by a liquid reduction and heat treatment method,and characterized by transmission electron microscopy and powder X-ray diffraction to explore and study the morphologies and crystallization properties.The an-nealing of the as prepared catalysts was performed at different temperatures,tested by electrochemical measurements, and proved to be of great importance for the improvement of the catalyst′s activity and durability due to the alloying effect.The catalysts annealed at 700 ℃ exhibited the highest area-specific activity and mass-specific activity which were 3-4 times higher than those of a commercial Pt/C catalyst.

  2. SISGR: Theoretically relating the surface composition of Pt alloys to their performance as the electrocatalysts of low-temperature fuel cells

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Guofeng

    2010-12-31

    The main goal of this project is to gain fundamental knowledge about the relation between surface composition and catalytic performance of Pt alloy catalysts for oxygen reduction reaction (ORR). Specific objectives are: to develop and improve a first-principles based multiscale computation approach to simulating surface segregation phenomena in Pt alloy surfaces; to evaluate the surface electronic structure and catalytic activity of Pt alloy catalysts and; to relate the surface composition to the catalytic performance of Pt alloy catalysts.

  3. Examining the surfaces in used platinum catalysts

    Directory of Open Access Journals (Sweden)

    Trumić B.

    2009-01-01

    Full Text Available For the purpose of finding more advanced platinum catalyst manufacturing technologies and achieving a higher degree of ammonia oxidation, metallographic characterization has been done on the surface of catalyst gauzes and catalyst gripper gauzes made from platinum and palladium alloys. For the examined samples of gauzes as well as the cross section of the wires, a chemical analysis was provided. The purpose of this paper is the metallographic characterization of examined alloys carried out by way of electronic microscopic scanning, X-rays as well as chemical assays which contributed greatly to a better understanding of the surface deactivation, in other words a better consideration of structural changes occurring on the wire surface.

  4. Heterogeneous Catalysts

    NARCIS (Netherlands)

    Dakka, J.; Sheldon, R.A.; Sanderson, W.A.

    1997-01-01

    Abstract of GB 2309655 (A) Heterogeneous catalysts comprising one or more metal compounds selected from the group consisting of tin, molybdenum, tungsten, zirconium and selenium compounds deposited on the surface of a silicalite are provided. Preferably Sn(IV) and/or Mo(VI) are employed. The cat

  5. Hearing Aids

    Science.gov (United States)

    ... more in both quiet and noisy situations. Hearing aids help people who have hearing loss from damage ... your doctor. There are different kinds of hearing aids. They differ by size, their placement on or ...

  6. AIDS (image)

    Science.gov (United States)

    AIDS (acquired immune deficiency syndrome) is caused by HIV (human immunodeficiency virus), and is a syndrome that ... life-threatening illnesses. There is no cure for AIDS, but treatment with antiviral medicine can suppress symptoms. ...

  7. Aid Effectiveness

    DEFF Research Database (Denmark)

    Arndt, Channing; Jones, Edward Samuel; Tarp, Finn

    Controversy over the aggregate impact of foreign aid has focused on reduced form estimates of the aid-growth link. The causal chain, through which aid affects developmental outcomes including growth, has received much less attention. We address this gap by: (i) specifying a structural model of th...

  8. Fundamental investigations of catalyst nanoparticles

    DEFF Research Database (Denmark)

    Elkjær, Christian Fink

    area Cu=ZnO=Al2O3 structure that is difficult to study by TEM. We therefore created size-selected CuZn alloy nanoparticles that were transformed by oxidation and reduction into Cu nanoparticles decorated with ZnO. This represents a simplified model system for the high surface area catalyst...... been unknown. We used nanoreactor technology which allows for simultaneous TEM imaging and activity measurement, also referred to as an Operando experiment. With this we revealed that the shape of the Pt nanoparticles changed in phase with changes in global reaction rate. By the use of reactor modeling...... fundamental understanding of catalytic processes and our ability to make use of that understanding. This thesis presents fundamental studies of catalyst nanoparticles with particular focus on dynamic processes. Such studies often require atomic-scale characterization, because the catalytic conversion takes...

  9. Catalyst Architecture

    DEFF Research Database (Denmark)

    Kiib, Hans; Marling, Gitte; Hansen, Peter Mandal

    2014-01-01

    of programs, have a role in mediating positive social and/or cultural development. In this sense, we talk about architecture as a catalyst for: sustainable adaptation of the city’s infrastructure appropriate renovation of dilapidated urban districts strengthening of social cohesiveness in the city development...... meaningful for everyone. The exhibited works are designed by SANAA, Diller Scofidio + Renfro, James Corner Field Operation, JBMC Arquitetura e Urbanismo, Atelier Bow-Wow, Ateliers Jean Nouvel, COBE, Transform, BIG, Topotek1, Superflex, and by visual artist Jane Maria Petersen....

  10. Study of ultrasonic vibration aided laser injection magnesium alloy solidification structure%超声振幅对激光熔注镁合金凝固组织的研究

    Institute of Scientific and Technical Information of China (English)

    赵明娟; 邓志成; 赵龙志; 张坚

    2015-01-01

    Based on the CA method,a grain growth model for simulation of microstructure evolution was estab-lished,and the influence of grain growth of magnesium alloy melt with different amplitude of ultrasonic vibra-tion was studied in this paper.The results show that with the increase of ultrasonic amplitude,melt undercoo-ling increases as power function,when the melt of undercooling was very small,the melt uncleats hardly,while the undercooling reaches a certain value,the nucleation rate increases dramatically.When amplitude was 10 μm,the undercooling induced by ultrasonic vibration was 32.23 K,and the nucleation rate for the melt was 353 times that of the melt without ultrasonic vibration.Under the ultrasonic vibration the alloy melt undercoo-ling increases,the melt nucleation rate increases,the grain size becomes smaller and more uniform.The simula-tion results are well in agreement with experimental results,which ensure that the simulation can guide the ap-plication of laser injection aided by ultrasonic vibration in industrial production.%采用 CA 法建立了镁合金晶粒生长模型,研究了超声振动作用下镁合金熔体的晶粒生长。结果表明,随着超声振幅的增大,熔体过冷度呈幂函数增大,熔体在过冷度很小时,基本不形核,达到一定值时,形核率急剧增加。当振幅达到10μm 时,超声振动提高的过冷度达到32.23 K,镁合金熔体形核率为未施加超声的353倍。超声振动的引入增大了合金熔体的过冷度,提高了熔体形核率,凝固组织平均晶粒尺寸减小,组织分布更均匀。模拟结果与试验结果相符,说明该模拟可以指导超声振动在辅助激光熔注工业生产中的应用。

  11. PROPERTIES OF POLYMER SUPPORTED Ni-Cu BIMETALLIC CATALYSTS PREPARED BY SOLVATED METAL ATOM IMPREGNATION

    Institute of Scientific and Technical Information of China (English)

    WU Shihua; ZHU Changying; HUANG Wenqiang

    1996-01-01

    D-72 resin supported nickel-copper catalysts prepared by solvated metal atom impregnation (SMAI) were studied by magnetic measurements and X-ray photoelectron spectroscopy (XPS). The Ni particles on the catalysts are very highly dispersed and display superparamagnetic behaviour. Ni-Cu alloy clusters were found to be formed. The surface compositions are different from the bulk concentrations. In contrast with the surface enrichment in copper generally observed on conventional Ni-Cu catalysts, the surfaces of these catalysts are enriched in nickel. The nickel is in both zero and valent states, while copper is mainly in metallic state. Catalytic data show that the formation of Ni-Cu alloy clusters has a profound effect on the catalytic activities of the catalysts in the hydrogenation of furfural. The activity of the Ni:Cu ratio of one bimetallic catalysts is much higher than that of the Ni or Cu monometallic catalyst.

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

    Institute of Scientific and Technical Information of China (English)

    Jinwei Chen; Chunping Jiang; Hui Lu; Lan Feng; Xin Yang; Liangqiong Li; Ruilin Wang

    2009-01-01

    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 H_2O or binary solvents of H_2O 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.

  13. ANALYSIS AND DEVELOPMENT OF COPPER RECYCLING OF DEAD COPPER-CONTAINING CATALYSTS

    OpenAIRE

    O. S. Komarov; I. V. Provorova; V. I. Volosatikov; D. O. Komarov; N. I. Urbanovich

    2009-01-01

    The technology of processing of copper-bearing dead catalysts, which includes leaching and deposition of copper by means of electrolysis and also their application in composition of the mixture for alloy doping is offered.

  14. ANALYSIS AND DEVELOPMENT OF COPPER RECYCLING OF DEAD COPPER-CONTAINING CATALYSTS

    Directory of Open Access Journals (Sweden)

    O. S. Komarov

    2009-01-01

    Full Text Available The technology of processing of copper-bearing dead catalysts, which includes leaching and deposition of copper by means of electrolysis and also their application in composition of the mixture for alloy doping is offered.

  15. Possibility of Wastewater Treatment Using MFC with Ni-Co Catalyst of Fuel Electrode

    Directory of Open Access Journals (Sweden)

    Włodarczyk Paweł P.

    2016-06-01

    Full Text Available One of the problems with microbial fuel cells is a low current density of those energy sources. Nonetheless, it is possible to increase the current density by using the catalyst for fuel electrode (anode - as long as a low cost catalyst can be found. The possibility of wastewater treatment using the Ni-Co alloy as catalyst for MFC’s is presented in this paper. The alloys were obtained with different concentrations of Co (15 and 50% of Co. The increase of current density with Ni-Co catalyst is approximately 0,1 mA/cm2. So, a fundamental possibility wastewater treatment using the Ni-Co alloy as catalyst for microbial fuel cells was presented.

  16. Possibility of Wastewater Treatment Using MFC with Ni-Co Catalyst of Fuel Electrode

    Science.gov (United States)

    Włodarczyk, Paweł P.; Włodarczyk, Barbara

    2016-06-01

    One of the problems with microbial fuel cells is a low current density of those energy sources. Nonetheless, it is possible to increase the current density by using the catalyst for fuel electrode (anode) - as long as a low cost catalyst can be found. The possibility of wastewater treatment using the Ni-Co alloy as catalyst for MFC's is presented in this paper. The alloys were obtained with different concentrations of Co (15 and 50% of Co). The increase of current density with Ni-Co catalyst is approximately 0,1 mA/cm2. So, a fundamental possibility wastewater treatment using the Ni-Co alloy as catalyst for microbial fuel cells was presented.

  17. Brand Aid

    DEFF Research Database (Denmark)

    Richey, Lisa Ann; Ponte, Stefano

    A critical account of the rise of celebrity-driven “compassionate consumption” Cofounded by the rock star Bono in 2006, Product RED exemplifies a new trend in celebrity-driven international aid and development, one explicitly linked to commerce, not philanthropy. Brand Aid offers a deeply informed...

  18. Foreign aid

    DEFF Research Database (Denmark)

    Tarp, Finn

    2008-01-01

    Foreign aid has evolved significantly since the Second World War in response to a dramatically changing global political and economic context. This article (a) reviews this process and associated trends in the volume and distribution of foreign aid; (b) reviews the goals, principles...

  19. Electrochemical catalyst recovery method

    Science.gov (United States)

    Silva, Laura J.; Bray, Lane A.

    1995-01-01

    A method of recovering catalyst material from latent catalyst material solids includes: a) combining latent catalyst material solids with a liquid acid anolyte solution and a redox material which is soluble in the acid anolyte solution to form a mixture; b) electrochemically oxidizing the redox material within the mixture into a dissolved oxidant, the oxidant having a potential for oxidation which is effectively higher than that of the latent catalyst material; c) reacting the oxidant with the latent catalyst material to oxidize the latent catalyst material into at least one oxidized catalyst species which is soluble within the mixture and to reduce the oxidant back into dissolved redox material; and d) recovering catalyst material from the oxidized catalyst species of the mixture. The invention is expected to be particularly useful in recovering spent catalyst material from petroleum hydroprocessing reaction waste products having adhered sulfides, carbon, hydrocarbons, and undesired metals, and as well as in other industrial applications.

  20. Electronic-Structure-Based Design of Ordered Alloys

    DEFF Research Database (Denmark)

    Bligaard, Thomas; Andersson, M.P.; Jacobsen, Karsten Wedel

    2006-01-01

    We describe some recent advances in the methodology of using electronic structure calculations for materials design. The methods have been developed for the design of ordered metallic alloys and metal alloy catalysts, but the considerations we present are relevant for the atomic-scale computation...

  1. Platinum and Palladium Alloys Suitable as Fuel Cell Electrodes

    DEFF Research Database (Denmark)

    2011-01-01

    and innovative catalyst compositions in fuel cell electrodes. The novel electrode catalysts of the invention comprise a noble metal selected from Pt, Pd and mixtures thereof alloyed with a further element selected from Sc, Y and La as well as any mixtures thereof, wherein said alloy is supported on a conductive......The present invention concerns electrode catalysts used in fuel cells, such as proton exchange membrane (PEM) fuel cells. The invention is related to the reduction of the noble metal content and the improvement of the catalytic efficiency by low level substitution of the noble metal to provide new...

  2. Hearing Aid

    Institute of Scientific and Technical Information of China (English)

    2003-01-01

    A man realized that he needed to purchase ahearing aid, but he was unwilling to spend muchmoney. "How much do they run?"he asked theclerk. "That depends," said. the salesman. "Theyrun from 2 to 2000."

  3. Hearing Aids

    Science.gov (United States)

    ... slightly different from the ITC and is nearly hidden in the ear canal. Both canal hearing aids ... Privacy Policy & Terms of Use Visit the Nemours Web site. Note: All information on TeensHealth® is for ...

  4. Design criteria for stable Pt/C fuel cell catalysts

    Directory of Open Access Journals (Sweden)

    Josef C. Meier

    2014-01-01

    Full Text Available Platinum and Pt alloy nanoparticles supported on carbon are the state of the art electrocatalysts in proton exchange membrane fuel cells. To develop a better understanding on how material design can influence the degradation processes on the nanoscale, three specific Pt/C catalysts with different structural characteristics were investigated in depth: a conventional Pt/Vulcan catalyst with a particle size of 3–4 nm and two Pt@HGS catalysts with different particle size, 1–2 nm and 3–4 nm. Specifically, Pt@HGS corresponds to platinum nanoparticles incorporated and confined within the pore structure of the nanostructured carbon support, i.e., hollow graphitic spheres (HGS. All three materials are characterized by the same platinum loading, so that the differences in their performance can be correlated to the structural characteristics of each material. The comparison of the activity and stability behavior of the three catalysts, as obtained from thin film rotating disk electrode measurements and identical location electron microscopy, is also extended to commercial materials and used as a basis for a discussion of general fuel cell catalyst design principles. Namely, the effects of particle size, inter-particle distance, certain support characteristics and thermal treatment on the catalyst performance and in particular the catalyst stability are evaluated. Based on our results, a set of design criteria for more stable and active Pt/C and Pt-alloy/C materials is suggested.

  5. Design criteria for stable Pt/C fuel cell catalysts.

    Science.gov (United States)

    Meier, Josef C; Galeano, Carolina; Katsounaros, Ioannis; Witte, Jonathon; Bongard, Hans J; Topalov, Angel A; Baldizzone, Claudio; Mezzavilla, Stefano; Schüth, Ferdi; Mayrhofer, Karl J J

    2014-01-01

    Platinum and Pt alloy nanoparticles supported on carbon are the state of the art electrocatalysts in proton exchange membrane fuel cells. To develop a better understanding on how material design can influence the degradation processes on the nanoscale, three specific Pt/C catalysts with different structural characteristics were investigated in depth: a conventional Pt/Vulcan catalyst with a particle size of 3-4 nm and two Pt@HGS catalysts with different particle size, 1-2 nm and 3-4 nm. Specifically, Pt@HGS corresponds to platinum nanoparticles incorporated and confined within the pore structure of the nanostructured carbon support, i.e., hollow graphitic spheres (HGS). All three materials are characterized by the same platinum loading, so that the differences in their performance can be correlated to the structural characteristics of each material. The comparison of the activity and stability behavior of the three catalysts, as obtained from thin film rotating disk electrode measurements and identical location electron microscopy, is also extended to commercial materials and used as a basis for a discussion of general fuel cell catalyst design principles. Namely, the effects of particle size, inter-particle distance, certain support characteristics and thermal treatment on the catalyst performance and in particular the catalyst stability are evaluated. Based on our results, a set of design criteria for more stable and active Pt/C and Pt-alloy/C materials is suggested.

  6. Non-noble catalysts and catalyst supports for phosphoric acid fuel cells

    Science.gov (United States)

    Mcalister, A. J.

    1981-01-01

    Tungsten carbide, which is active for hydrogen oxidation, is CO tolerant and has a hexagonal structure is discussed. Titanium carbide is inactive and has a cubic structure. Four different samples of the cubic alloys W sub x-1Ti sub XC sub 1-y were found to be active and CO tolerant. When the activities of these cubic alloys are weighted by the reciprocal of the square to those of highly forms of WC. They offer important insight into the nature of the active sites on W-C anode catalysts for use in phosphoric acid fuel cells.

  7. Foundation Flash Catalyst

    CERN Document Server

    Goralski, Greg

    2010-01-01

    This book offers an introduction to Flash Catalyst for designers with intermediate to advanced skills. It discusses where Catalyst sits within the production process and how it communicates with other programs. It covers all of the features of the Flash Catalyst workspace, teaching you how to create designs from scratch, how to build application designs and add functionality, and how to master the Catalyst/Flex workflow. * Introduces Flash Catalyst * Focuses on production process * Covers the interrelation between Flash Catalyst and Photoshop/Illustrator/Flex/Flash What you'll learn Starting f

  8. Preparation and Hydrodesulfurization Performance of Ni-B Amorphous Alloy Catalyst Supported by APTS Modified SBA-15%APTS改性SBA-15负载Ni-B非晶态合金催化剂的制备及加氢脱硫性能

    Institute of Scientific and Technical Information of China (English)

    谌伟庆; 黄勇; 石秋杰

    2012-01-01

    SBA-15 was modified by APTS with covalent grafting method,and then Ni-B amorphous alloy catalysts were prepared by using APTS modified SBA-15 and unmodified SBA-15 as supports.The catalytic activities of both catalysts were characterized,and thiophene hydrodesulfurization was selected as probe reaction.The results show that thiophene conversation of Ni-B/SBA-15-APTS is 50.8%,which is higher than the one of Ni-B/SBA-15.The complexation between NH2 and Ni2+ would be benefit for dispersion of Ni-B alloy particles and reduction of Ni2+.According to ICP results,Ni-B/SBA-15-APTS show bigger quantity of Ni in support and higher content of Ni in Ni-B amorphous alloy than Ni-B/SBA-15,resulting in the higher activity.%采用共价接枝法制备APTS改性介孔分子筛SBA-15,将氨基官能团接枝到SBA-15表面.并采用化学还原法制备了Ni-B/SBA-15-APTS非晶态合金催化剂,以噻吩加氢脱硫为探针反应,研究了其催化加氢脱硫性能.结果表明,240℃时,APTS改性SBA-15所负载的Ni-B催化剂噻吩转化率达到50.8%,较未改性SBA-15所负载的催化剂噻吩转化率有显著地提高.由于氨基与Ni2+的配合作用,有助于Ni在催化剂中的分散,因而更容易被还原.ICP结果表明,在相同的制备条件下,相比未改性的SBA-15,APTS改性SBA-15使其催化剂中Ni的负载量增加,并且非晶态合金组成中Ni的含量也增大,B的含量降低,有利于提高催化剂的活性.

  9. In silico search for novel methane steam reforming catalysts

    DEFF Research Database (Denmark)

    Xu, Yue; Lausche, Adam C; Wang, Shengguang

    2013-01-01

    This paper demonstrates a method for screening transition metal and metal alloy catalysts based on their predicted rates and stabilities for a given catalytic reaction. This method involves combining reaction and activation energies (available to the public via a web-based application ‘CatApp’) w...

  10. Types of Hearing Aids

    Science.gov (United States)

    ... Devices Consumer Products Hearing Aids Types of Hearing Aids Share Tweet Linkedin Pin it More sharing options ... some features for hearing aids? What are hearing aids? Hearing aids are sound-amplifying devices designed to ...

  11. Low-Pt-Content Anode Catalyst for Direct Methanol Fuel Cells

    Science.gov (United States)

    Narayanan, Sekharipuram; Whitacre, Jay

    2008-01-01

    Combinatorial experiments have led to the discovery that a nanophase alloy of Pt, Ru, Ni, and Zr is effective as an anode catalyst material for direct methanol fuel cells. This discovery has practical significance in that the electronic current densities achievable by use of this alloy are comparable or larger than those obtained by use of prior Pt/Ru catalyst alloys containing greater amounts of Pt. Heretofore, the high cost of Pt has impeded the commercialization of direct methanol fuel cells. By making it possible to obtain a given level of performance at reduced Pt content (and, hence, lower cost), the discovery may lead to reduction of the economic impediment to commercialization.

  12. Pd Close Coupled Catalyst

    Institute of Scientific and Technical Information of China (English)

    Zhong Hua SHI; Mao Chu GONG; Yao Qiang CHEN

    2006-01-01

    A catalyst comprised novel high surface area alumina support was prepared to control emission of automobiles. The results showed that prepared catalyst could satisfy the requirements of a high performance close coupled catalyst for its good catalytic activity at low temperature and good stability at high temperature.

  13. Bifunctional anode catalysts for direct methanol fuel cells

    DEFF Research Database (Denmark)

    Rossmeisl, Jan; Ferrin, Peter; Tritsaris, Georgios

    2012-01-01

    Using the binding energy of OH* and CO* on close-packed surfaces as reactivity descriptors, we screen bulk and surface alloy catalysts for methanol electro-oxidation activity. Using these two descriptors, we illustrate that a good methanol electro-oxidation catalyst must have three key properties......: (1) the ability to activate methanol, (2) the ability to activate water, and (3) the ability to react off surface intermediates (such as CO* and OH*). Based on this analysis, an alloy catalyst made up of Cu and Pt should have a synergistic effect facilitating the activity towards methanol electro....... Adding Cu to a Pt(111) surface increases the methanol oxidation current by more than a factor of three, supporting our theoretical predictions for improved electrocatalysts....

  14. Structure and Stability of Pt-Y Alloy Particles for Oxygen Reduction Studied by Electron Microscopy

    DEFF Research Database (Denmark)

    Deiana, Davide; Wagner, Jakob Birkedal; Hansen, Thomas Willum

    2015-01-01

    Platinum-yttrium alloy nanoparticles show both a high activity and stability for the oxygen reduction reaction. The catalysts were prepared by magnetron sputter aggregation and mass filtration providing a model catalyst system with a narrow size distribution. The structure and stability...... of nanostructured Pt-Y alloy catalysts were studied using transmission electron microscopy techniques. Using elemental X-ray mapping and high-resolution electron microscopy, the specific compositional structure and distribution of the individual nanoparticles was unraveled and the stability assessed. Studying...... the catalyst after reaction and after aging tests shows the development of a core-shell type structure after being exposed to reaction conditions....

  15. Brand Aid

    DEFF Research Database (Denmark)

    Richey, Lisa Ann; Ponte, Stefano

    2011-01-01

    activists, scholars and venture capitalists, discusses the pros and cons of changing the world by ‘voting with your dollars’. Lisa Ann Richey and Stefano Ponte (Professor at Roskilde University and Senior Researcher at DIIS respectively), authors of Brand Aid: Shopping Well to Save the World, highlight how...

  16. Vapor phase hydrogenation of furfural over nickel mixed metal oxide catalysts derived from layered double hydroxides

    Energy Technology Data Exchange (ETDEWEB)

    Sulmonetti, Taylor P.; Pang, Simon H.; Claure, Micaela Taborga; Lee, Sungsik; Cullen, David A.; Agrawal, Pradeep K.; Jones, Christopher W.

    2016-05-01

    The hydrogenation of furfural is investigated over various reduced nickel mixed metal oxides derived from layered double hydroxides (LDHs) containing Ni-Mg-Al and Ni-Co-Al. Upon reduction, relatively large Ni(0) domains develop in the Ni-Mg-Al catalysts, whereas in the Ni-Co-Al catalysts smaller metal particles of Ni(0) and Co(0), potentially as alloys, are formed, as evidenced by XAS, XPS, STEM and EELS. All the reduced Ni catalysts display similar selectivities towards major hydrogenation products (furfuryl alcohol and tetrahydrofurfuryl alcohol), though the side products varied with the catalyst composition. The 1.1Ni-0.8Co-Al catalyst showed the greatest activity per titrated site when compared to the other catalysts, with promising activity compared to related catalysts in the literature. The use of base metal catalysts for hydrogenation of furanic compounds may be a promising alternative to the well-studied precious metal catalysts for making biomass-derived chemicals if catalyst selectivity can be improved in future work by alloying or tuning metal-oxide support interactions.

  17. Electrochemical oxidation of carbon monoxide: from platinum single crystals to low temperature fuel catalysts. Part II: Electrooxidation of H2, CO and H2/CO mixtures on well characterized PtMo alloy

    Directory of Open Access Journals (Sweden)

    PHILIP N. ROSS JR.

    2003-03-01

    Full Text Available The oxidation of hydrogen and hydrogen–carbon monoxide mixture has been investigated on well-characterized metallurgically prepared platinum–molybdenum (PtMo alloys. It was concluded that the optimum surface concentration of molybdenum is near 23 mol.%. Based on experimentally determined parameters and simulations, the mechanism of the oxidation of CO/H2 mixtures is discussed.

  18. A bioinspired iron catalyst for nitrate and perchlorate reduction.

    Science.gov (United States)

    Ford, Courtney L; Park, Yun Ji; Matson, Ellen M; Gordon, Zachary; Fout, Alison R

    2016-11-11

    Nitrate and perchlorate have considerable use in technology, synthetic materials, and agriculture; as a result, they have become pervasive water pollutants. Industrial strategies to chemically reduce these oxyanions often require the use of harsh conditions, but microorganisms can efficiently reduce them enzymatically. We developed an iron catalyst inspired by the active sites of nitrate reductase and (per)chlorate reductase enzymes. The catalyst features a secondary coordination sphere that aids in oxyanion deoxygenation. Upon reduction of the oxyanions, an iron(III)-oxo is formed, which in the presence of protons and electrons regenerates the catalyst and releases water.

  19. Fabrication and evaluation of nickel cobalt alloy electrocatalysts for alkaline water splitting

    Energy Technology Data Exchange (ETDEWEB)

    Hong, Sung Hoon [School of Integrative Engineering, Chung-Ang University, Heukseokno 84, Dongjak-gu, Seoul 156-756 (Korea, Republic of); Ahn, Sang Hyun; Choi, Insoo [Fuel Cell Research Center, Korea Institute of Science and Technology, Hwarangno 14-gil 5, Seongbuk-gu, Seoul 136-791 (Korea, Republic of); Pyo, Sung Gyu [School of Integrative Engineering, Chung-Ang University, Heukseokno 84, Dongjak-gu, Seoul 156-756 (Korea, Republic of); Kim, Hyoung-Juhn; Jang, Jong Hyun [Fuel Cell Research Center, Korea Institute of Science and Technology, Hwarangno 14-gil 5, Seongbuk-gu, Seoul 136-791 (Korea, Republic of); Kim, Soo-Kil, E-mail: sookilkim@cau.ac.kr [School of Integrative Engineering, Chung-Ang University, Heukseokno 84, Dongjak-gu, Seoul 156-756 (Korea, Republic of)

    2014-07-01

    As a catalyst for the hydrogen evolution reaction (HER) in alkaline water splitting, NiCo alloys of various compositions were prepared through electrodeposition onto Cu substrates. The composition of each alloy catalyst was varied by controlling the molar ratio of Co{sup 2+} ions in the electrolyte. With an increase in the Co content, the morphologies of the NiCo alloys were progressively changed from a round to polygonal shape. The NiCo alloys all exhibited a Ni rich surface, as confirmed by the bulk-to-surface compositional ratio and degree of alloying. The catalytic activities of the NiCo alloys toward the HER of water splitting were electrochemically tested in a KOH electrolyte, and the specific activities were characterized by considering the electrochemical surface areas of Ni and Co. The effect of alloying was demonstrated to be a significant enhancement of HER activity, resulting from a change in the electronic structures of Ni and Co.

  20. Tactile Aids

    Directory of Open Access Journals (Sweden)

    Mohtaramossadat Homayuni

    1996-04-01

    Full Text Available Tactile aids, which translate sound waves into vibrations that can be felt by the skin, have been used for decades by people with severe/profound hearing loss to enhance speech/language development and improve speechreading.The development of tactile aids dates from the efforts of Goults and his co-workers in the 1920s; Although The power supply was too voluminous and it was difficult to carry specially by children, it was too huge and heavy to be carried outside the laboratories and its application was restricted to the experimental usage. Nowadays great advances have been performed in producing this instrument and its numerous models is available in markets around the world.

  1. Negotiating Aid

    DEFF Research Database (Denmark)

    Whitfield, Lindsay; Fraser, Alastair

    2011-01-01

    This article presents a new analytical approach to the study of aid negotiations. Building on existing approaches but trying to overcome their limitations, it argues that factors outside of individual negotiations (or the `game' in game-theoretic approaches) significantly affect the preferences...... of actors, the negotiating strategies they fashion, and the success of those strategies. This approach was employed to examine and compare the experiences of eight countries: Botswana, Ethiopia, Ghana, Mali, Mozambique, Rwanda, Tanzania and Zambia. The article presents findings from these country studies...... which investigated the strategies these states have adopted in talks with aid donors, the sources of leverage they have been able to bring to bear in negotiations, and the differing degrees of control that they have been able to exercise over the policies agreed in negotiations and those implemented...

  2. Robust CoAl Alloy: Highly Active, Reusable and Green Catalyst in the Hydrogenolysis of Glycerol%Robust CoAl Alloy: Highly Active, Reusable and Green Catalyst in the Hydrogenolysis of Glycerol

    Institute of Scientific and Technical Information of China (English)

    郭晓洋; 尹安远; 郭晓东; 郭秀英; 戴维林; 范康年

    2011-01-01

    CoAl alloy catalyst is found, for the first time, to be highly active, selective and reusable for the synthesis of diols via the hydrogenolysis of glycerol under mild conditions. The products and the catalyst could be self-separated from the reaction system through a simple reactor.

  3. Resin Catalyst Hybrids

    Institute of Scientific and Technical Information of China (English)

    S. Asaoka

    2005-01-01

    @@ 1Introduction: What are resin catalyst hybrids? There are typically two types of resin catalyst. One is acidic resin which representative is polystyrene sulfonic acid. The other is basic resin which is availed as metal complex support. The objective items of this study on resin catalyst are consisting of pellet hybrid, equilibrium hybrid and function hybrid of acid and base,as shown in Fig. 1[1-5].

  4. Towards the Rational Design of Nanoparticle Catalysts

    Science.gov (United States)

    Dash, Priyabrat

    stabilization in BMIMPF6 IL is described, and have shown that nanoparticle stability and catalytic activity of nanoparticles is dependent on the overall stability of the nanoparticles towards aggregation (manuscript submitted). The second major project is focused on synthesizing structurally well-defined supported catalysts by incorporating the nanoparticle precursors (both alloy and core shell) into oxide frameworks (TiO2 and Al2O 3), and examining their structure-property relationships and catalytic activity. a full article has been published on this project (Journal of Physical Chemistry C, 2009, 113, 12719) in which a route to rationally design supported catalysts from structured nanoparticle precursors with precise control over size, composition, and internal structure of the nanoparticles has been shown. In a continuation of this methodology for the synthesis of heterogeneous catalysts, efforts were carried out to apply the same methodology in imidazolium-based ILs as a one-pot media for the synthesis of supported-nanoparticle heterogeneous catalysts via the trapping of pre-synthesized nanoparticles into porous inorganic oxide materials. Nanoparticle catalysts in highly porous titania supports were synthesized using this methodology (manuscript to be submitted).

  5. Synergetic effects leading to coke-resistant NiCo bimetallic catalysts for dry reforming of methane

    KAUST Repository

    Li, Lidong

    2015-01-08

    A new dry reforming of methane catalyst comprised of NiCo bimetallic nanoparticles and a Mgx(Al)O support that exhibits high coke resistance and long-term on-stream stability is reported. The structural characterization by XRD, TEM, temperature-programmed reduction, and BET analysis demonstrates that the excellent performance of this catalyst is ascribed to the synergy of various parameters, including metal-nanoparticle size, metal-support interaction, catalyst structure, ensemble size, and alloy effects.

  6. Facile Synthesis of Nanoporous Pt-Y alloy with Enhanced Electrocatalytic Activity and Durability

    Science.gov (United States)

    Cui, Rongjing; Mei, Ling; Han, Guangjie; Chen, Jiyun; Zhang, Genhua; Quan, Ying; Gu, Ning; Zhang, Lei; Fang, Yong; Qian, Bin; Jiang, Xuefan; Han, Zhida

    2017-02-01

    Recently, Pt-Y alloy has displayed an excellent electrocatalytic activity for oxygen reduction reaction (ORR), and is regarded as a promising cathode catalyst for fuel cells. However, the bulk production of nanoscaled Pt-Y alloy with outstanding catalytic performance remains a great challenge. Here, we address the challenge through a simple dealloying method to synthesize nanoporous Pt-Y alloy (NP-PtY) with a typical ligament size of ~5 nm. By combining the intrinsic superior electrocatalytic activity of Pt-Y alloy with the special nanoporous structure, the NP-PtY bimetallic catalyst presents higher activity for ORR and ethanol oxidation reaction, and better electrocatalytic stability than the commercial Pt/C catalyst and nanoporous Pt alloy. The as-made NP-PtY holds great application potential as a promising electrocatalyst in proton exchange membrane fuel cells due to the advantages of facile preparation and excellent catalytic performance.

  7. Manufacture of Raney Ni catalyst with metastable Ni2Al3 by high-energy milling

    Institute of Scientific and Technical Information of China (English)

    1999-01-01

    The Ni-Al alloy containing Cr, Fe additives were prepared as Raney Ni catalyst by high energy milling. The size and surface state of Ni-Al alloy powder were studied by particle size analyzer and sanning electron microscopy, the structure was analyzed by XRD and Mossbauer methods. The results showed that after a high-energy milling (HEM), the Ni-Al alloy transforms to a nano-scale NiAl structure with rich Al. Byannealing the alloy, a metastable Ni2Al3 phase can be obtained.

  8. Manufacture of Raney Ni catalyst with metastable Ni2Al3 by high—energy milling

    Institute of Scientific and Technical Information of China (English)

    滕荣厚; 马如璋; 等

    1999-01-01

    The Ni-Al alloy containing Cr,Fe additives were prepared as Raney Ni Catalyst by high energy milling.The size and surface state of Ni-Al alloy powder were studied by particle size analyzer and sanning electron microscopy.the Structure was analyzed by XRD and Moessbauer methods.The results showed that after a high-energy milling(HEM).the Ni-Al alloy transforms to a nano-scale NiAl structure with rich Al.By annealing the alloy,a metastable Ni2Al3 phase can be obtained.

  9. Ternary alloy nanocatalysts for hydrogen evolution reaction

    Indian Academy of Sciences (India)

    SOUMEN SAHA; SONALIKA VAIDYA; KANDALAM V RAMANUJACHARY; SAMUEL E LOFLAND; ASHOK K GANGULI

    2016-04-01

    Cu–Fe–Ni ternary alloys (size ∼55–80 nm) with varying compositions viz. CuFeNi (A1), CuFe2Ni (A2) and CuFeNi2 (A3) were successfully synthesized using microemulsion. It is to be noted that synthesis of nanocrystallineternary alloys with precise composition is a big challenge which can be overcome by choosing an appropriate microemulsion system. High electrocatalytic activity towards HER in alkaline medium was achieved by the formation of alloys of metals with low and high binding energies. A high value of current density (228 mA cm$^2$) at an overpotential of 545 mV was obtained for CuFeNi (A1), which is significantly high as compared to the previously reported Ni$_{59}$Cu$_{41}$ alloy catalyst.

  10. Teaching AIDS.

    Science.gov (United States)

    Short, R V

    1989-06-01

    This article reviews a peer group Acquired Immunodeficiency Syndrome (AIDS) educational program at a university in Australia. Studies in the US have shown that most adolescents, although sexually active, do not believe they are likely to become infected with the Human Immunodeficiency Virus, and therefore do not attempt to modify their sexual behavior. A 1st step in educating students is to introduce them to condoms and impress upon them the fact that condoms should be used at the beginning of all sexual relationships, whether homosexual or heterosexual. In this program 3rd year medical students were targeted, as they are effective communicators and disseminators of information to the rest of the student body. After class members blow up condoms, giving them a chance to handle various brands and observe the varying degrees of strength, statistical evidence about the contraceptive failure rate of condoms (0.6-14.7 per 100 women-years) is discussed. Spermicides, such as nonoxynol-9 used in conjunction with condoms, are also discussed, as are condoms for women, packaging and marketing of condoms, including those made from latex and from the caecum of sheep, the latter condoms being of questionable effectiveness in preventing transmission of the virus. The care of terminal AIDS cases and current global and national statistics on AIDS are presented. The program also includes cash prizes for the best student essays on condom use, the distribution of condoms, condom key rings and T-shirts, and a student-run safe sex stand during orientation week. All of these activities are intended to involve students and attract the interest of the undergraduate community. Questionnaires administered to students at the end of the course revealed that the lectures were received favorably. Questionnaires administered to new medical and English students attending orientation week revealed that 72% of students thought the stand was a good idea and 81% and 83%, respectively found it

  11. Brand Aid

    DEFF Research Database (Denmark)

    Richey, Lisa Ann; Ponte, Stefano

    2011-01-01

    activists, scholars and venture capitalists, discusses the pros and cons of changing the world by ‘voting with your dollars’. Lisa Ann Richey and Stefano Ponte (Professor at Roskilde University and Senior Researcher at DIIS respectively), authors of Brand Aid: Shopping Well to Save the World, highlight how......Can Citizen Consumers Make a Difference? DIIS researcher contributes to a Boston Review - New Democracy Forum In the current issue of Boston Review (November/December 2011), contributors to a ‘New Democracy Forum’ debate whether Citizen Consumers can make a difference in stimulating responsible...

  12. 以非晶态合金催化剂SRNA-4为固相的气液固磁稳定床的界面传质研究%Interphase Mass Transfer in G-L-S Magnetically Stabilized Bed with Amorphous Alloy SRNA-4 Catalyst

    Institute of Scientific and Technical Information of China (English)

    李(韦华); 宗保守; 李晓芳; 孟祥坤; 张金利

    2006-01-01

    Gas-liquid (G-L) and liquid-solid (L-S) mass transfer coefficients were characterized in a gas-liquid-solid(G-L-S) three-phase magnetically stabilized bed (MSB) using amorphous alloy SRNA-4 as the solid phase. Effects such as superficial liquid velocity, superficial gas velocity, magnetic strength, liquid viscosity, and particle size were investigated. Experimental results indicated that the G-L volumetric mass transfer coefficients (KLa) increased along with the magnetic strength, superficial gas and liquid velocities. Proper increase of liquid viscosity promoted KLa only in the range of lower liquid viscosity. The external magnetic field made L-S mass transfer coefficients (Ks)in the G-L-S MSB lower than those of conventional fluidized beds. Ks in the MSB almost kept constant as the superficial liquid velocity and superficial gas velocity increased and decreased with the liquid viscosity and surface tension, while increased with the particle size Ks showed uniform axial and radial distributions except of small decreases close to the wall. Dimensionless correlations were established to estimate KLa and Ks of the MSB with SRNA-4 catalysts, which showed the average error of 5.4% and 2.5% respectively.

  13. Aluminum alloy

    Science.gov (United States)

    Blackburn, Linda B. (Inventor); Starke, Edgar A., Jr. (Inventor)

    1989-01-01

    This invention relates to aluminum alloys, particularly to aluminum-copper-lithium alloys containing at least about 0.1 percent by weight of indium as an essential component, which are suitable for applications in aircraft and aerospace vehicles. At least about 0.1 percent by weight of indium is added as an essential component to an alloy which precipitates a T1 phase (Al2CuLi). This addition enhances the nucleation of the precipitate T1 phase, producing a microstructure which provides excellent strength as indicated by Rockwell hardness values and confirmed by standard tensile tests.

  14. Titania Supported Pt and Pt/Pd Nano-particle Catalysts for the Oxidation of Sulfur Dioxide

    DEFF Research Database (Denmark)

    Koutsopoulos, Sotiris; Johannessen, Tue; Eriksen, Kim Michael

    2006-01-01

    Several types of titania (anatase) were used as supports for pure platinum and Pt–Pd bimetallic alloy catalysts. The preparation methods, normal wet impregnation technique and flame aerosol synthesis, obtained metal loadings of 2% by weight. The prepared catalysts were tested for SO2 oxidation...... activity at atmospheric pressure in the temperature range 250–600 °C. The SO2 to SO3 conversion efficiency of the Pt–Pd alloy was significantly higher than that of the individual metals. The effects of the preparation method and the titania type used on the properties and activity of the resulting catalyst...

  15. Catalyst for Ammonia Oxidation

    DEFF Research Database (Denmark)

    2015-01-01

    The present invention relates to a bimetallic catalyst for ammonia oxidation, a method for producing a bimetallic catalyst for ammonia oxidation and a method for tuning the catalytic activity of a transition metal. By depositing an overlayer of less catalytic active metal onto a more catalytic...

  16. Reducible oxide based catalysts

    Science.gov (United States)

    Thompson, Levi T.; Kim, Chang Hwan; Bej, Shyamal K.

    2010-04-06

    A catalyst is disclosed herein. The catalyst includes a reducible oxide support and at least one noble metal fixed on the reducible oxide support. The noble metal(s) is loaded on the support at a substantially constant temperature and pH.

  17. Magnetic catalyst bodies

    NARCIS (Netherlands)

    Teunissen, Wendy; Bol, A.A.; Geus, John W.

    2001-01-01

    After a discussion about the importance of the size of the catalyst bodies with reactions in the liquid-phase with a suspended catalyst, the possibilities of magnetic separation are dealt with. Deficiencies of the usual ferromagnetic particles are the reactivity and the clustering of the particles.

  18. Studies on PEM Fuel Cell Noble Metal Catalyst Dissolution

    DEFF Research Database (Denmark)

    Ma, Shuang; Skou, Eivind Morten

    . Membrane Electrode Assembly (MEA) is commonly considered as the heart of cell system [2]. Degradation of the noble metal catalysts in MEAs especially Three-Phase-Boundary (TPB) is a key factor directly influencing fuel cell durability. In this work, electrochemical degradation of Pt and Pt/Ru alloy were......Incredibly vast advance has been achieved in fuel cell technology regarding to catalyst efficiency, improvement of electrolyte conductivity and optimization of cell system. With breathtakingly accelerating progress, Proton Exchange Membrane Fuel Cells (PEMFC) is the most promising and most widely...

  19. Effects of Cu over Pd based catalysts supported on silica or niobia

    Directory of Open Access Journals (Sweden)

    Roma M.N.S.C.

    2000-01-01

    Full Text Available Palladium and palladium-copper catalysts supported on silica and niobia were characterized by H2 chemisorption and H2-O2 titration. Systems over silica were also analyzed by transmission electron microscopy and EXAFS. The metallic dispersion decreased from 20% to 7% when the content of Pd was increased from 0.5wt.-% to 3wt.-% in monometallic catalysts. The addition of 3 wt.-% Cu to obtain Pd-Cu catalysts caused a remarkable capacity loss of hydrogen chemisorption. TPR analysis suggested an interaction between the two metals and EXAFS characterization of the catalyst supported on silica confirmed the formation of Pd-Cu alloy. Pd/Nb2O5 catalysts showed turnover numbers higher than those obtained with the Pd/SiO2 systems in the cyclohexane dehydrogenation. However, the bimetallic catalysts showed very low turnover numbers.

  20. Adsorbate induced surface alloy formation investigated by near ambient pressure X-ray photoelectron spectroscopy

    DEFF Research Database (Denmark)

    Nierhoff, Anders Ulrik Fregerslev; Conradsen, Christian Nagstrup; McCarthy, David Norman

    2014-01-01

    Formation of meta-stable surface-alloys can be used as a way to tune the binding strength of reaction intermediates and could therefore be used as improved catalyst materials for heterogeneous catalysis. Understanding the role of adsorbates on such alloy surfaces can provide new insights for engi...

  1. Hydrogen absorption induced metal deposition on palladium and palladium-alloy particles

    Science.gov (United States)

    Wang, Jia X.; Adzic, Radoslav R.

    2009-03-24

    The present invention relates to methods for producing metal-coated palladium or palladium-alloy particles. The method includes contacting hydrogen-absorbed palladium or palladium-alloy particles with one or more metal salts to produce a sub-monoatomic or monoatomic metal- or metal-alloy coating on the surface of the hydrogen-absorbed palladium or palladium-alloy particles. The invention also relates to methods for producing catalysts and methods for producing electrical energy using the metal-coated palladium or palladium-alloy particles of the present invention.

  2. Controllable galvanic synthesis of triangular Ag-Pd alloy nanoframes for efficient electrocatalytic methanol oxidation.

    Science.gov (United States)

    Xu, Lin; Luo, Zhimin; Fan, Zhanxi; Yu, Sijia; Chen, Junze; Liao, Yusen; Xue, Can

    2015-06-08

    Triangular Ag-Pd alloy nanoframes were successfully synthesized through galvanic replacement by using Ag nanoprisms as sacrificial templates. The ridge thickness of the Ag-Pd alloy nanoframes could be readily tuned by adjusting the amount of the Pd source during the reaction. These obtained triangular Ag-Pd alloy nanoframes exhibit superior electrocatalytic activity for the methanol oxidation reaction as compared with the commercial Pd/C catalyst due to the alloyed Ag-Pd composition as well as the hollow-framed structures. This work would be highly impactful in the rational design of future bimetallic alloy nanostructures with high catalytic activity for fuel cell systems.

  3. Catalysts, methods of making catalysts, and methods of use

    KAUST Repository

    Renard, Laetitia

    2014-03-06

    Embodiments of the present disclosure provide for catalysts, methods of making catalysts, methods of using catalysts, and the like. In an embodiment, the method of making the catalysts can be performed in a single step with a metal nanoparticle precursor and a metal oxide precursor, where a separate stabilizing agent is not needed.

  4. Confinement dependence of electro-catalysts for hydrogen evolution from water splitting

    Directory of Open Access Journals (Sweden)

    Mikaela Lindgren

    2014-02-01

    Full Text Available Density functional theory is utilized to articulate a particular generic deconstruction of the electrode/electro-catalyst assembly for the cathode process during water splitting. A computational model was designed to determine how alloying elements control the fraction of H2 released during zirconium oxidation by water relative to the amount of hydrogen picked up by the corroding alloy. This model is utilized to determine the efficiencies of transition metals decorated with hydroxide interfaces in facilitating the electro-catalytic hydrogen evolution reaction. A computational strategy is developed to select an electro-catalyst for hydrogen evolution (HE, where the choice of a transition metal catalyst is guided by the confining environment. The latter may be recast into a nominal pressure experienced by the evolving H2 molecule. We arrived at a novel perspective on the uniqueness of oxide supported atomic Pt as a HE catalyst under ambient conditions.

  5. Electrical Resistance Alloys and Low-Expansion Alloys

    DEFF Research Database (Denmark)

    Kjer, Torben

    1996-01-01

    The article gives an overview of electrical resistance alloys and alloys with low thermal expansion. The electrical resistance alloys comprise resistance alloys, heating alloys and thermostat alloys. The low expansion alloys comprise alloys with very low expansion coefficients, alloys with very low...

  6. Evaluating the role of Lead In A Novel Ternary Catalysts For DMFCs

    CERN Document Server

    Halder, Aditi; Trahan, Matthew; Mukerjee, Sanjeev

    2012-01-01

    The current density at lower potential is highly desirable in fuel cell technology and crucial center point for designing a new catalyst. By alloying platinum with various other metals, the improvisation of the fuel cell catalyst has achieved a lot of attention and interests. In this article, a novel porous ternary alloy PtPb@Ru as anode catalysts for direct methanol fuel cell had been synthesized by micro-emulsion technique. The catalysts had been characterized by various spectroscopic and microscopic techniques. The activity and durability of the catalysts had been tested by running cyclic voltammetry in 0.1 M HClO4 and 1M Methanol. To explain the many fold increase in current density of the PtPb@Ru catalysts in comparison to the commercial available PtRu catalysts, in situ X-ray absorption spectroscopy (XAS) measurements, at the PtL3 edge (XANES and EXAFS) were carried out on the PtPb@Ru catalysts in an electrochemical cell. The down-shift in the d-band center of platinum observed in the XAS study, might b...

  7. Thermal Stability of Nanoporous Raney Gold Catalyst

    Directory of Open Access Journals (Sweden)

    Matthew C. Tai

    2015-07-01

    Full Text Available Nanoporous “Raney gold” sponge was prepared by de-alloying an Au-Al precursor alloy. Catalytic tests using a micro-reactor confirmed that Raney gold can serve as an active heterogeneous catalyst for CO oxidation, reduction of NO to N2, and oxidation of NO to NO2. In general, the specific surface area of a heterogeneous catalyst has an influence on its catalytic efficacy. Unfortunately, gold sponges coarsen readily, leading to sintering of their structure and reduction in surface area. This potentially places constraints on their upper operating temperature in catalytic reactors. Here we analyzed the behavior of Raney gold when the temperature was raised. We examined the kinetics and mechanism of coarsening of the sponge using a combination of in situ optical measurements and Metropolis Monte Carlo modeling with a Lennard-Jones interatomic potential. Modeling showed that the sponges started with an isotropic “foamy” morphology with negative average “mean curvature” but that subsequent thermally activated coarsening will drive the morphology through a bi-continuous fibrous state and on, eventually, to a sponge consisting of sintered blobs of predominantly positive “mean curvature”.

  8. AIDS.gov

    Science.gov (United States)

    ... concerns. Search Services Share This Help National HIV/AIDS Strategy Check out NHAS's latest progress in the ... from AIDS.gov Read more AIDS.gov tweets AIDS.gov HIV/AIDS Basics • Federal Resources • Using New ...

  9. Aids for Handicapped Readers.

    Science.gov (United States)

    Library of Congress, Washington, DC. Div. for the Blind and Physically Handicapped.

    The reference circular provides information on approximately 50 reading and writing aids intended for physically or visually handicapped individuals. Described are low vision aids, aids for holding a book or turning pages, aids for reading in bed, handwriting aids, typewriters and accessories, braille writing equipment, sound reproducers, and aids…

  10. Catalyst in Basic Oleochemicals

    Directory of Open Access Journals (Sweden)

    Eva Suyenty

    2007-10-01

    Full Text Available Currently Indonesia is the world largest palm oil producer with production volume reaching 16 million tones per annum. The high crude oil and ethylene prices in the last 3 – 4 years contribute to the healthy demand growth for basic oleochemicals: fatty acids and fatty alcohols. Oleochemicals are starting to replace crude oil derived products in various applications. As widely practiced in petrochemical industry, catalyst plays a very important role in the production of basic oleochemicals. Catalytic reactions are abound in the production of oleochemicals: Nickel based catalysts are used in the hydrogenation of unsaturated fatty acids; sodium methylate catalyst in the transesterification of triglycerides; sulfonic based polystyrene resin catalyst in esterification of fatty acids; and copper chromite/copper zinc catalyst in the high pressure hydrogenation of methyl esters or fatty acids to produce fatty alcohols. To maintain long catalyst life, it is crucial to ensure the absence of catalyst poisons and inhibitors in the feed. The preparation methods of nickel and copper chromite catalysts are as follows: precipitation, filtration, drying, and calcinations. Sodium methylate is derived from direct reaction of sodium metal and methanol under inert gas. The sulfonic based polystyrene resin is derived from sulfonation of polystyrene crosslinked with di-vinyl-benzene. © 2007 BCREC UNDIP. All rights reserved.[Presented at Symposium and Congress of MKICS 2007, 18-19 April 2007, Semarang, Indonesia][How to Cite: E. Suyenty, H. Sentosa, M. Agustine, S. Anwar, A. Lie, E. Sutanto. (2007. Catalyst in Basic Oleochemicals. Bulletin of Chemical Reaction Engineering and Catalysis, 2 (2-3: 22-31.  doi:10.9767/bcrec.2.2-3.6.22-31][How to Link/DOI: http://dx.doi.org/10.9767/bcrec.2.2-3.6.22-31 || or local: http://ejournal.undip.ac.id/index.php/bcrec/article/view/6

  11. Macroeconomic Issues in Foreign Aid

    DEFF Research Database (Denmark)

    Hjertholm, Peter; Laursen, Jytte; White, Howard

    foreign aid, macroeconomics of aid, gap models, aid fungibility, fiscal response models, foreign debt,......foreign aid, macroeconomics of aid, gap models, aid fungibility, fiscal response models, foreign debt,...

  12. ALKALI RESISTANT CATALYST

    DEFF Research Database (Denmark)

    2008-01-01

    The present invention concerns the selective removal of nitrogen oxides (NOx) from gasses. In particular, the invention concerns a process, a catalyst and the use of a catalyst for the selective removal of nitrogen oxides in the presence of ammonia from gases containing a significant amount...... of alkali metal and/or alkali-earth compounds which process comprises using a catalyst combined of (i) a formed porous superacidic support, said superacidic support having an Hammett acidity stronger than Ho=-12, and (ii) a metal oxide catalytic component deposited on said superacidic support selected from...

  13. Characterization and Catalytic Properties of a Rapidly Quenched Ni-RE-P-AL Catalyst

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    A Ni-RE-P-AL catalyst prepared by alkaline extraction of a rapidly quenched Ni-RE-P-AL alloy was characterized by means of ICP,BET,XRD,ZPS and TEM.The results show that the rapidly quenched Ni-RE-P-AL alloy contained less crystalline AL3Ni than AL-Ni alloy.After alkaline extraction,most of Al in the Ni-RE-P-AL alloy was leached out and the resulted Ni-RE-P-AL catalyst presented a spone structure similar to Raney Ni.Although Crystalline Ni is the major phase in the Ni-RE-P-AL catalyst and Raney Ni,amorphous Ni-P phase has been detected in the Ni-RE-P-AL catalyst.Studies on catalytic hydrogenation of toluene,phenyl ethylene,acetylene benzene,nitrobenzene,cyclohexanone and adiponitrile in liquid phase showed that the activity and selectivity of this Ni-RE-P-AL catalyst are superior to those of Raney Ni,especially at low temperatures.The amorphous phase is considered to be responsible for its superior catalytic properties.

  14. Crawling Aid

    Science.gov (United States)

    1982-01-01

    The Institute for the Achievement of Human Potential developed a device known as the Vehicle for Initial Crawling (VIC); the acronym is a tribute to the crawler's inventor, Hubert "Vic" Vykukal; is an effective crawling aid. The VIC is used by brain injured children who are unable to crawl due to the problems of weight-bearing and friction, caused by gravity. It is a rounded plywood frame large enough to support the child's torso, leaving arms and legs free to move. On its underside are three aluminum discs through which air is pumped to create an air-bearing surface that has less friction than a film of oil. Upper side contains the connection to the air supply and a pair of straps which restrain the child and cause the device to move with him. VIC is used with the intent to recreate the normal neurological connection between brain and muscles. Over repetitive use of the device the child develops his arm and leg muscles as well as coordination. Children are given alternating therapy, with and without the VIC until eventually the device is no longer needed.

  15. HIV and AIDS

    Science.gov (United States)

    ... Emergency Room? What Happens in the Operating Room? HIV and AIDS KidsHealth > For Kids > HIV and AIDS ... actually the virus that causes the disease AIDS. HIV Hurts the Immune System People who are HIV ...

  16. Heart attack first aid

    Science.gov (United States)

    First aid - heart attack; First aid - cardiopulmonary arrest; First aid - cardiac arrest ... A heart attack occurs when the blood flow that carries oxygen to the heart is blocked. The heart muscle ...

  17. Breathing difficulties - first aid

    Science.gov (United States)

    Difficulty breathing - first aid; Dyspnea - first aid; Shortness of breath - first aid ... Breathing difficulty is almost always a medical emergency. An exception is feeling slightly winded from normal activity, ...

  18. Catalyst for microelectromechanical systems microreactors

    Science.gov (United States)

    Morse, Jeffrey D.; Sopchak, David A.; Upadhye, Ravindra S.; Reynolds, John G.; Satcher, Joseph H.; Gash, Alex E.

    2010-06-29

    A microreactor comprising a silicon wafer, a multiplicity of microchannels in the silicon wafer, and a catalyst coating the microchannels. In one embodiment the catalyst coating the microchannels comprises a nanostructured material. In another embodiment the catalyst coating the microchannels comprises an aerogel. In another embodiment the catalyst coating the microchannels comprises a solgel. In another embodiment the catalyst coating the microchannels comprises carbon nanotubes.

  19. Epoxidation catalyst and process

    Science.gov (United States)

    Linic, Suljo; Christopher, Phillip

    2010-10-26

    Disclosed herein is a catalytic method of converting alkenes to epoxides. This method generally includes reacting alkenes with oxygen in the presence of a specific silver catalyst under conditions suitable to produce a yield of the epoxides. The specific silver catalyst is a silver nanocrystal having a plurality of surface planes, a substantial portion of which is defined by Miller indices of (100). The reaction is performed by charging a suitable reactor with this silver catalyst and then feeding the reactants to the reactor under conditions to carry out the reaction. The reaction may be performed in batch, or as a continuous process that employs a recycle of any unreacted alkenes. The specific silver catalyst has unexpectedly high selectivity for epoxide products. Consequently, this general method (and its various embodiments) will result in extraordinarily high epoxide yields heretofore unattainable.

  20. Evaluation of nanostructured Pt-Ru catalyst for application in DMFC

    Energy Technology Data Exchange (ETDEWEB)

    Ocampo, A.L.; Gamboa, S.A. [Centro de Investigacion en Energia-UNAM, Morelos (Mexico); Sebastien, P.J. [Centro de Investigacion en Energia-UNAM, Morelos (Mexico)]|[Chiapas Politecnica Univ., Chiapas (Mexico); Morgado, J.; Montoya, J.A. [IMP, Eje Central Lazaro Cardenas, (Mexico); Savadogo, O. [Ecole Polytechnique, Montreal, PQ (Canada). Laboratoire d' electrochimie et de materiaux energetiques

    2006-07-01

    Slow methanol oxidation kinetics and the poisoning of the anode catalyst are the major factors that limit the performance of the direct methanol fuel cell (DMFC). Catalysts with higher catalytic activity are needed in order to overcome these challenges. Although platinum (Pt) is a good catalyst for methanol oxidation, it can be highly affected by carbon monoxide (CO) reaction intermediates. Superior catalytic activity occurs in Pt based alloys, such as platinum ruthenium (Pt-Ru), platinum molybdenum (Pt-Mo), platinum tin (Pt-Sn), and platinum osmium (Pt-Os). This is due to the bifunctional mechanism and/or by the electronic effect, which indicates a promotional effect of the alloyed metal on Pt. The most studied binary system is the Pt-Ru (ruthenium), which has shown the best catalytic activity. There are many factors that influence the physical properties and the electrochemical performance of the Pt-Ru catalyst. These include the preparation method; the atomic ratio between platinum and ruthenium; the nature of the catalyst support; and, an optional heat treatment. Other important factors such as the particle size, the morphology, the electrochemically active area, and the crystalline phase influence the physical properties. In this study, nanostructured Pt-Ru catalysts were fabricated and evaluated physicochemically and electrochemically for its use in direct methanol fuel cell (DMFC). The catalysts were synthesized from the carbonyl compounds of Pt and Ru via a pyrolysis-condensation reaction. The high resolution results showed a homogenous distribution of the nanostructured catalysts on Vulcan support. The catalyst was evaluated by XRD, HRTEM, electrochemical impedance spectroscopy and the methanol oxidation on the catalyst was studied using volt-amperometry. The performance of the catalyst was found to be similar or better than the commercial one. It was concluded that it is possible to synthesize Pt-Ru/C with good morphological characteristics and improve it

  1. New Catalysts for ROMP

    Institute of Scientific and Technical Information of China (English)

    H. Berke; C. Frech; A. Lhamazares; O. Blacque; H.W. Schmalle; C. Adlhart; P. Chen

    2005-01-01

    @@ 1Introduction Ring Opening Metathesis Polymerization (ROMP) is based on the olefin metathesis reaction, which requires transition metal catalysts. Mainly molybdenum, tungsten and ruthenium based catalysts have up to now been used. The "in-between" metal rhenium was only rarely applied in olefin metathesis reactions, and not at all in ROMP processes.We have found that cationic phosphine substituted dinitrosyl rhenium complexes[1]1a and 1b effectively catalyze ROMP of norbonene, dicyclopentadiene and of cyclooctene. See Fig. 1.

  2. Methanol Electro-Oxidation on Pt-Ru Alloy Nanoparticles Supported on Carbon Nanotubes

    Directory of Open Access Journals (Sweden)

    Yangchuan Xing

    2009-09-01

    Full Text Available Carbon nanotubes (CNTs have been investigated in recent years as a catalyst support for proton exchange membrane fuel cells. Improved catalyst activities were observed and attributed to metal-support interactions. We report a study on the kinetics of methanol electro-oxidation on CNT supported Pt-Ru alloy nanoparticles. Alloy catalysts with different compositions, Pt53Ru47/CNT, Pt69Ru31/CNT and Pt77Ru23/CNT, were prepared and investigated in detail. Experiments were conducted at various temperatures, electrode potentials, and methanol concentrations. It was found that the reaction order of methanol electro-oxidation on the PtRu/CNT catalysts was consistent with what has been reported for PtRu alloys with a value of 0.5 in methanol concentrations. However, the electro-oxidation reaction on the PtRu/CNT catalysts displayed much lower activation energies than that on the Pt-Ru alloy catalysts unsupported or supported on carbon black (PtRu/CB. This study provides an overall kinetic evaluation of the PtRu/CNT catalysts and further demonstrates the beneficial role of CNTs.

  3. Preparation and influence of performance of anodic catalysts for direct methanol fuel cell

    Institute of Scientific and Technical Information of China (English)

    WANG Zhenbo; YIN Geping; SHI Pengfei

    2007-01-01

    This research aims at increasing the utilization of platinum-ruthenium alloy (Pt-Ru) catalysts and thus lowering the catalyst loading in anodes for methanol electrooxidation.The direct methanol fuel cell's (DMFC) anodic catalysts,Pt-Ru/C,were prepared by chemical reduction with a reducing agent added in two kinds of solutions under different circumstances.The reducing agent was added in hot solution with the protection of inert gases or just air,and in cold solution with inert gases.The catalysts were treated at different temperatures.Their performance was tested by cyclic voltammetry and potentiostatic polarization by utilizing their inherent powder microelectrode in 0.5 mol/L CH3OH and 0.5 mol/L H2SO4 solution.The structures and micro-surface images ofthe catalysts were determined and observed by X-ray diffraction and transmission electron microscopy,respectively.The catalyst prepared in inert gases showed a better catalytic performance for methanol electrooxidation than that prepared in air.It resulted in a more homogeneous distribution of the Pt-Ru alloy in carbon.Its size is small,only about 4.5 nm.The catalytic performance is affected by the order of the reducing agent added.The performance of the catalyst prepared by adding the reductant at constant temperature of the solution is better than that prepared by adding it in the solution at 0℃ and then heating it up to the reducing temperature.The structure of the catalyst was modified,and there was an increase in the conversion of ruthenium into the alloyed state and an increase in particle size with the ascension of heat treatment temperature.In addition,the stability of the catalyst was improved after heat treatment.

  4. In situ investigation of catalysts for alcohol synthesis

    DEFF Research Database (Denmark)

    Duchstein, Linus Daniel Leonhard; Sharafutdinov, Irek; Wu, Qiongxiao

    The need for studying catalyst under realistic conditions is emphasized both by academic and industrial research. Acquiring highly resolved local information from materials under realistic environments by means of Transmission Electron Microscopy (TEM) has been found to be essential in connecting...... microscopic and macroscopic properties of materials, e.g. relating catalytic performance with crystal structure and morphology. This study presents extensive characterization of NiGa and CuNi alloys during catalyst formation, alcohol synthesis, and accelerated aging experiments. The characterization platform...... for observation in a gaseous environment. By using heating holders, dynamic information about catalysts in their working state can be gained using a variety of TEM techniques. The presented platform successfully illustrates the capability of correlating the dynamic changes in structural phase and particle size...

  5. Search for new catalysts from a fundamental basis

    Energy Technology Data Exchange (ETDEWEB)

    Andersen, M.; Lytken, O.; Engbaek, J.; Nielsen, G.; Schumacher, N.; Johansson, M.; Chorkendorff, I. [Interdisciplinary Research Center for Catalysis (ICAT), Department of Physics and Department of Chemical Engineering, Building 312, Technical University of Denmark (DTU), DK-2800 Kongens Lyngby (Denmark)

    2005-02-15

    In this overview, we present some of our more fundamental approaches for making new and/or improved catalysts. First, the effect of mono atomic steps is discussed both in relation to the mechanism of the ammonia synthesis, and in terms of relevance for other reactions, such as the steam reforming and methanization processes. The possibility for utilizing steps to improve selectivity is also discussed. It is shown how micro kinetic modelling can be used to predict how the catalyst for the WGS reaction could be improved. Furthermore, an experimental technique is demonstrated, where alloys consisting of up to four metals can be tested under realistic conditions without loosing the ability to study the catalysts with surface science techniques both prior to and after they have been subjected to reaction conditions. Finally, the importance of in situ measurements will be demonstrated for some preliminary investigations of systems of relevance to fuel cell technology.

  6. Synthesis of CuNi/C and CuNi/γ-Al2O3 Catalysts for the Reverse Water Gas Shift Reaction

    Directory of Open Access Journals (Sweden)

    Maxime Lortie

    2015-01-01

    Full Text Available A new polyol synthesis method is described in which CuNi nanoparticles of different Cu/Ni atomic ratios were supported on both carbon and gamma-alumina and compared with Pt catalysts using the reverse water gas shift, RWGS, reaction. All catalysts were highly selective for CO formation. The concentration of CH4 was less than the detection limit. Cu was the most abundant metal on the CuNi alloy surfaces, as determined by X-ray photoelectron spectroscopy, XPS, measurements. Only one CuNi alloy catalyst, Cu50Ni50/C, appeared to be as thermally stable as the Pt/C catalysts. After three temperature cycles, from 400 to 700°C, the CO yield at 700°C obtained using the Cu50Ni50/C catalyst was comparable to that obtained using a Pt/C catalyst.

  7. Methanol-Tolerant Cathode Catalyst Composite For Direct Methanol Fuel Cells

    Science.gov (United States)

    Zhu, Yimin; Zelenay, Piotr

    2006-03-21

    A direct methanol fuel cell (DMFC) having a methanol fuel supply, oxidant supply, and its membrane electrode assembly (MEA) formed of an anode electrode and a cathode electrode with a membrane therebetween, a methanol oxidation catalyst adjacent the anode electrode and the membrane, an oxidant reduction catalyst adjacent the cathode electrode and the membrane, comprises an oxidant reduction catalyst layer of a platinum-chromium alloy so that oxidation at the cathode of methanol that crosses from the anode through the membrane to the cathode is reduced with a concomitant increase of net electrical potential at the cathode electrode.

  8. New catalysts for coal processing: Metal carbides and nitrides

    Energy Technology Data Exchange (ETDEWEB)

    S. Ted Oyama; David F. Cox

    1999-12-03

    The subject of this research project was to investigate the catalytic properties of a new class of materials, transition metal carbides and nitrides, for treatment of coal liquid and petroleum feedstocks. The main objectives were: (1) preparation of catalysts in unsupported and supported form; (2) characterization of the materials; (3) evaluation of their catalytic properties in HDS and HDN; (4) measurement of the surface properties; and (5) observation of adsorbed species. All of the objectives were substantially carried out and the results will be described in detail below. The catalysts were transition metal carbides and nitrides spanning Groups 4--6 in the Periodic Table. They were chosen for study because initial work had shown they were promising materials for hydrotreating. The basic strategy was first to prepare the materials in unsupported form to identify the most promising catalyst, and then to synthesize a supported form of the material. Already work had been carried out on the synthesis of the Group VI compounds Mo{sub 2}C, Mo{sub 2}N, and WC, and new methods were developed for the Group V compounds VC and NbC. All the catalysts were then evaluated in a hydrotreating test at realistic conditions. It was found that the most active catalyst was Mo{sub 2}C, and further investigations of the material were carried out in supported form. A new technique was employed for the study of the bulk and surface properties of the catalysts, near edge x-ray absorption spectroscopy (NEXAFS), that fingerprinted the electronic structure of the materials. Finally, two new research direction were explored. Bimetallic alloys formed between two transition metals were prepared, resulting in catalysts having even higher activity than Mo{sub 2}C. The performance of the catalysts in hydrodechloration was also investigated.

  9. Evaluation of luminol chemiluminescence based on simultaneous introducing of coumarin derivatives as green fluorophores and chitosan-induced Au/Ag alloy nanoparticle as catalyst for the sensitive determination of glucose.

    Science.gov (United States)

    Chaichi, M J; Alijanpour, S O; Asghari, S; Shadlou, S

    2015-03-01

    We report herein the development of a novel chemiluminescence system based on simultaneous introducing of synthetic coumarin derivatives and chitosan-induced Au/Ag alloy NPs on the luminol CL system and suggest how it may be useful for determination of glucose. Chitosan-induced Au/Ag nanoalloys in the coumarin derivatives intensified-luminol CL system, in addition to catalyze CL reaction can make a change in the process of coumarin derivatives effect as fluorophore on the luminol CL system. This phenomenon is caused by interaction between active functional groups of coumarin derivatives and chitosan. The interaction strength depends on the coumarin derivatives' structure and their substituents. Considering the inevitable trend luminol radical and superoxide anion radical to absorption on the surface of the embedded Au/Ag nanoalloy in the chitosan matrix, it can be concluded that chitosan acts as a platform for all reagents involved in the CL reaction including coumarin derivatives, Au/Ag nanoalloy and luminol, and electron-transfer taking place on it; Placing all chemiluminescent reagents together on the chitosan network can lead to a powerful CL due to increasing rigidity of CL system. The most efficient coumarin derivative on the Au/Ag nanoalloy-fluorophore-luminol-H2O2 CL system, in relation to interaction capability with chitosan' functional groups, was selected and the CL condition in presence of it was optimized. Whereas the glucose oxidase-mediated oxidation of glucose yields gluconic acid and H2O2, under optimum condition the most efficient CL system was applied to detection of glucose due to enzymatically production of hydrogen peroxide. The linear response range of 1.5 × 10(-6)-5.0 × 10(-3) M and the detection limit (defined as the concentration that could be detected at the signal-to-noise ratio of 3) of 7.5 × 10(-7) M was found for the glucose standards. Also, the developed method was successfully applied to determination of glucose in

  10. Enlarged test catalysts during the hydrogenation of 1,4-butynediol to 1,4-butanediol

    Directory of Open Access Journals (Sweden)

    Zhaksyntay Kairbekov

    2013-09-01

    Full Text Available The highly effective catalyzer for butynediol-1;4 hydrogenation was designed and synthesized. Enlarged tests showed that the selectivity on butanediol-1.4 at the hydrogenation of butynediol-1.4 on the alloyed catalyst SKN-39H during 320 h was 84.6 %; that on 18 % higher than for  industrial MNH. The yield of product on the catalyst SKN-39 increases slowly from 3.1 to 7.3 % when on a catalyst MNH – 7.1 to 11.7 % from the initial content of butynediol-1;4. At the hydrogenation of  butynediol on catalyst SKN-39H process efficiency increases in 1.5-2 times and product purity on 2-3 % is higher in comparing with the industrial catalyst MNH. 

  11. Metal catalysts for steam reforming of tar derived from the gasification of lignocellulosic biomass.

    Science.gov (United States)

    Li, Dalin; Tamura, Masazumi; Nakagawa, Yoshinao; Tomishige, Keiichi

    2015-02-01

    Biomass gasification is one of the most important technologies for the conversion of biomass to electricity, fuels, and chemicals. The main obstacle preventing the commercial application of this technology is the presence of tar in the product gas. Catalytic reforming of tar appears a promising approach to remove tar and supported metal catalysts are among the most effective catalysts. Nevertheless, improvement of catalytic performances including activity, stability, resistance to coke deposition and aggregation of metal particles, as well as catalyst regenerability is greatly needed. This review focuses on the design and catalysis of supported metal catalysts for the removal of tar in the gasification of biomass. The recent development of metal catalysts including Rh, Ni, Co, and their alloys for steam reforming of biomass tar and tar model compounds is introduced. The role of metal species, support materials, promoters, and their interfaces is described.

  12. Home Health Aides

    Science.gov (United States)

    ... specifications Help to keep clients engaged in their social networks and communities Home health aides, unlike personal care aides , typically work ... self-care and everyday tasks. They also provide social supports and assistance that enable clients to participate in their ... more information about home health aides, including voluntary credentials for aides, visit ...

  13. Aid and Development

    DEFF Research Database (Denmark)

    Tarp, Finn

    Foreign aid looms large in the public discourse; and international development assistance remains squarely on most policy agendas concerned with growth, poverty and inequality in Africa and elsewhere in the developing world. The present review takes a retrospective look at how foreign aid has...... evolved since World War II in response to a dramatically changing global political and economic context. I review the aid process and associated trends in the volume and distribution of aid and categorize some of the key goals, principles and institutions of the aid system. The evidence on whether aid has...... for aid in the future...

  14. Types of Foreign Aid

    DEFF Research Database (Denmark)

    Bjørnskov, Christian

    Foreign aid is given for many purposes and different intentions, yet most studies treat aid flows as a unitary concept. This paper uses factor analysis to separate aid flows into different types. The main types can be interpreted as aid for economic purposes, social purposes, and reconstruction......; a residual category captures remaining purposes. Estimating the growth effects of separable types of aid suggests that most aid has no effects while reconstruction aid has direct positive effects. Although this type only applies in special circumstances, it has become more prevalent in more recent years....

  15. Study of Mg Powder as Catalyst Carrier for the Carbon Nanotube Growth by CVD

    Directory of Open Access Journals (Sweden)

    Jianli Kang

    2011-01-01

    Full Text Available The possibility of using magnesium powder as catalyst carrier for carbon nanotube growth by chemical vapor deposition, which may pave a new way to in situ fabricate CNT/Mg composites with high CNT dispersion, was investigated for the first time. The fabrication process of the catalyst supported on Mg powder involves the preparation of colloid by a deposition-precipitation method, followed by calcination and reduction. The results show that the interaction between catalyst and support plays an important role for the catalytic property of the catalyst. Ni alloyed with Mg shows no activity for the decomposition of methane. The introduction of Y in Ni/Mg catalyst can promote the reaction temperature between Ni and Mg and thus enhance the activity of the catalyst. A large amount of carbon nanotubes (CNTs with an average diameter of 20 nm was obtained using Ni/Y/Mg catalyst at 450∘C, while only a few short CNTs were obtained using Ni/Mg catalyst due to the low activity of the catalyst at lower temperature.

  16. Supported organoiridium catalysts for alkane dehydrogenation

    Science.gov (United States)

    Baker, R. Thomas; Sattelberger, Alfred P.; Li, Hongbo

    2013-09-03

    Solid supported organoiridium catalysts, a process for preparing such solid supported organoiridium catalysts, and the use of such solid supported organoiridium catalysts in dehydrogenation reactions of alkanes is provided. The catalysts can be easily recovered and recycled.

  17. Fuel cell catalyst degradation

    DEFF Research Database (Denmark)

    Arenz, Matthias; Zana, Alessandro

    2016-01-01

    Fuel cells are an important piece in our quest for a sustainable energy supply. Although there are several different types of fuel cells, the by far most popular is the proton exchange membrane fuel cell (PEMFC). Among its many favorable properties are a short start up time and a high power density...... increasing focus. Activity of the catalyst is important, but stability is essential. In the presented perspective paper, we review recent efforts to investigate fuel cell catalysts ex-situ in electrochemical half-cell measurements. Due to the amount of different studies, this review has no intention to give...

  18. Aerogel derived catalysts

    Energy Technology Data Exchange (ETDEWEB)

    Reynolds, J. G., LLNL

    1996-12-11

    Aerogels area class of colloidal materials which have high surface areas and abundant mesoporous structure. SiO{sub 2} aerogels show unique physical, optical and structural properties. When catalytic metals are incorporated in the aerogel framework, the potential exists for new and very effective catalysts for industrial processes. Three applications of these metal-containing SiO{sub 2} aerogels as catalysts are briefly reviewed in this paper--NO{sub x} reduction, volatile organic compound destruction, and partial oxidation of methane.

  19. Olefin metathesis catalyst

    Energy Technology Data Exchange (ETDEWEB)

    Kukes, S.G.; Banks, R.L.

    1986-05-20

    A process is described for preparing a disproportionation catalyst comprising admixing a catalytically effective amount of a calcined and activated catalyst consisting essentially of at least one metal oxide selected from molybdenum oxide and tungsten oxide and a support containing a major proportion of silica or alumina with a promoting amount of a methylating agent selected from the group consisting of dimethyl sulfate, dimethylsulfoxide, trimethyloxonium tetrafluorborate, methyl iodide, and methyl bromide, and subjecting same to inert atmospheric conditions for the methylating agent to promote the activity of the calcined molybdenum and tungsten oxides for the disproportionation of olefins.

  20. Mesoporous molecular sieve catalysts

    DEFF Research Database (Denmark)

    Højholt, Karen Thrane

    be used as solid acid catalysts but can also be used as a size-selective matrix. It was shown that it is possible to encapsulate 1-2 nm sized gold nanoparticles by silicalite-1 or ZSM-5 zeolite crystals thereby forming a sintering-stable and substrate size-selective oxidation catalyst. After carrying out...... calcination experiments, both in situ and ex situ indicated that the gold nanoparticles embedded in the crystals were highly stable towards sintering. The catalytic tests proved that the embedded gold nanoparticles were active in selective aldehyde oxidation and were only accessible through the micropores...

  1. Dynamics of Catalyst Nanoparticles

    DEFF Research Database (Denmark)

    Hansen, Thomas Willum; Cavalca, Filippo; Wagner, Jakob Birkedal

    under gas exposure, dynamic phenomena such as sintering and growth can be observed with sub-Ångstrøm resolution. Metal nanoparticles contain the active sites in heterogeneous catalysts, which are important for many industrial applications including the production of clean fuels, chemicals...... and pharmaceuticals, and the cleanup of exhaust from automobiles and stationary power plants. Sintering, or thermal deactivation, is an important mechanism for the loss of catalyst activity. In order to initiate a systematic study of the dynamics and sintering of nanoparticles, various catalytic systems have been...

  2. Precious metal-support interaction in automotive exhaust catalysts

    Institute of Scientific and Technical Information of China (English)

    郑婷婷; 何俊俊; 赵云昆; 夏文正; 何洁丽

    2014-01-01

    Precious metal-support interaction plays an important role in thermal stability and catalytic performance of the automotive exhaust catalysts. The support is not only a carrier for active compounds in catalysts but also can improve the dispersion of precious metals and suppress the sintering of precious metals at high temperature;meanwhile, noble metals can also enhance the redox per-formance and oxygen storage capacity of support. The mechanism of metal-support interactions mainly includes electronic interaction, formation of alloy and inward diffusion of metal into the support or covered by support. The form and degree of precious metal-sup-port interaction depend on many factors, including the content of precious metal, the species of support and metal, and preparation methods. The research results about strong metal-support interaction (SMSI) gave a theory support for developing a kind of new cata-lyst with excellent performance. This paper reviewed the interaction phenomenon and mechanism of precious metals (Pt, Pd, Rh) and support such as Al2O3, CeO2, and CeO2-based oxides in automotive exhaust catalysts. The factors that affect SMSI and the catalysts developed by SMSI were also discussed.

  3. Carbon nanotube synthesis with different support materials and catalysts

    Science.gov (United States)

    Gümüş, Fatih; Yuca, Neslihan; Karatepe, Nilgün

    2013-09-01

    Having remarkable characteristics, carbon nanotubes (CNTs) have attracted a lot of interest. Their mechanical, electrical, thermal and chemical properties make CNTs suitable for several applications such as electronic devices, hydrogen storage, textile, drug delivery etc. CNTs have been synthesized by various methods, such as arc discharge, laser ablation and catalytic chemical vapor deposition (CCVD). In comparison with the other techniques, CCVD is widely used as it offers a promising route for mass production. High capability of decomposing hydrocarbon formation is desired for the selected catalysts. Therefore, transition metals which are in the nanometer scale are the most effective catalysts. The common transition metals that are being used are Fe, Co, Ni and their binary alloys. The impregnation of the catalysts over the support material has a crucial importance for the CNT production. In this study, the influence of the support materials on the catalytic activity of metals was investigated. CNTs have been synthesized over alumina (Al2O3), silica (SiO2) and magnesium oxide (MgO) supported Fe, Co, Fe-Co catalysts. Catalyst - support material combinations have been investigated and optimum values for each were compared. Single walled carbon nanotubes (SWCNTs) were produced at 800°C. The duration of synthesis was 30 minutes for all support materials. The synthesized materials were characterized by thermal gravimetric analysis (TGA), Raman spectroscopy and transmission electron microscopy.

  4. Fuel cell electrocatalsis : oxygen reduction on Pt-based nanoparticle catalysts

    NARCIS (Netherlands)

    Vliet, Dennis Franciscus van der

    2010-01-01

    The thesis contains a discussion on the subject of the Oxygen Reduction Reaction (ORR) on Pt-alloy nanoparticle catalysts in the Rotating Disk Electrode (RDE) method. An insight in some of the difficulties of this method is given with proper solutions and compensations for these problems. Pt3Co, Au-

  5. Using supported Au nanoparticles as starting material for preparing uniform Au/Pd bimetallic catalysts

    Energy Technology Data Exchange (ETDEWEB)

    Villa, Alberto [Universita di Milano, Italy; Prati, Laura [Universita di Milano, Italy; Su, Dangshen [Fritz Haber Institute of the Max Planck Society, Berlin, Germany; Wang, Di [Fritz Haber Institute of the Max Planck Society, Berlin, Germany; Veith, Gabriel M [ORNL

    2010-01-01

    One of the best methods for producing bulk homogeneous (composition) supported bimetallic AuPd clusters involves the immobilization of a protected Au seed followed by the addition of Pd. This paper investigates the importance of this gold seed in controlling the resulting bimetallic AuPd clusters structures, sizes and catalytic activities by investigating three different gold seeds. Uniform Au-Pd alloy were obtained when a steric/electrostatic protecting group, poly(vinyl alcohol) (PVA), was used to form the gold clusters on activated carbon (AC). In contrast Au/AC precursors prepared using Au nanoparticles with only electrostatic stabilization (tetrakis(hydroxypropyl)phosphonium chloride (THPC)), or no stabilization (magnetron sputtering) produced inhomogeneous alloys and segregation of the gold and palladium. The uniform alloyed catalyst (Pd{at}Au{sub PVA}/AC) is the most active and selective catalyst, while the inhomogenous catalysts are less active and selective. Further study of the PVA protected Au clusters revealed that the amount of PVA used is also critical for the preparation of uniform alloyed catalyst, their stability, and their catalytic activity.

  6. Non-metallic catalysts for diamond synthesis under high pressure and high temperature

    Institute of Scientific and Technical Information of China (English)

    孙力玲; 吴奇; 戴道扬; 张君; 秦志成; 王文魁

    1999-01-01

    Recent results on conversion from graphite to diamond by aid of non-metallic catalysts are reviewed. The current status of experimental advances is presented and typical examples from relevant literature are provided for understanding the mechanism of the graphite-diamond conversion by aid of these non-metallic catalysts. Furthermore, a tendency of graphite-diamond transformation assisted by carbonates, sulfates or phosphorus under high pressure and high temperature has been investigated by calculating the activation energy and transformation probability of the carbon atoms over a potential barrier. It was found that the activation energy is highly sensitive to the catalyst chosen. The probability sequence of graphite-diamond transformation with these catalysts was put forward.

  7. Combinatorial Density Functional Theory-Based Screening of Surface Alloys for the Oxygen Reduction Reaction

    DEFF Research Database (Denmark)

    Greeley, Jeffrey Philip; Nørskov, Jens Kehlet

    2009-01-01

    A density functional theory (DFT)-based, combinatorial search for improved oxygen reduction reaction (ORR) catalysts is presented. A descriptor-based approach to estimate the ORR activity of binary surface alloys, wherein alloying occurs only in the surface layer, is described, and rigorous...... for the ORR but, with few exceptions, they are found to be thermodynamically unstable in the acidic environments typical of low-temperature fuel cells. The results suggest that, absent other thermodynamic or kinetic mechanisms to stabilize the alloys, surface alloys are unlikely to serve as useful ORR...

  8. Dependence on composition of electronic properties and stability of Pt-Fe/C catalysts for oxygen reduction

    Energy Technology Data Exchange (ETDEWEB)

    Malheiro, A.R.; Perez, J.; Villullas, H.M. [Departamento de Fisico-Quimica, Instituto de Quimica, Universidade Estadual Paulista - UNESP, Caixa Postal 355, R. Francisco Degni, s/n, CEP 14801-970, Araraquara, SP (Brazil)

    2010-11-01

    This work presents studies of electronic characteristics and alloy stability carried out for Pt-Fe/C catalysts of different compositions (10-50% Fe, in atoms) and same particle size. The electronic properties are characterized by in situ dispersive X-ray absorption spectroscopy (DXAS). The results show a steady decrease in Pt d-band occupancy as the amount of Fe in the alloy increases. The alloy stability is evaluated by prolonged potential cycling up to 1.0 V. Catalysts with Fe content up to 30% show good stabilities and keep their activities for oxygen reduction after prolonged cycling. In contrast, catalysts with Fe content above 30% suffer pronounced Fe leaching. (author)

  9. Deactivation-resistant catalyst for selective catalyst reduction of NOx

    DEFF Research Database (Denmark)

    2011-01-01

    The present invention relates to a catalyst for selective catalytic reduction of NOx in alkali metal containing flue gas using ammonia as reductant, the catalyst comprising a surface with catalytically active sites, wherein the surface is at least partly coated with a coating comprising at least...... one metal oxide. In another aspect the present invention relates to the use of said catalyst and to a method of producing said catalyst. In addition, the present invention relates to a method of treating an catalyst for conferring thereon an improved resistance to alkali poisoning....

  10. Formic acid oxidation at platinum-bismuth catalysts

    Directory of Open Access Journals (Sweden)

    Popović Ksenija Đ.

    2015-01-01

    Full Text Available The field of heterogeneous catalysis, specifically catalysis on bimetallic surfaces, has seen many advances over the past few decades. Bimetallic catalysts, which often show electronic and chemical properties that are distinct from those of their parent metals, offer the opportunity to obtain new catalysts with enhanced selectivity, activity, and stability. The oxidation of formic acid is of permanent interest as a model reaction for the mechanistic understanding of the electrooxidation of small organic molecules and because of its technical relevance for fuel cell applications. Platinum is one of the most commonly used catalysts for this reaction, despite the fact that it shows a few significant disadvantages: high cost and extreme susceptibility to poisoning by CO. To solve this problem, several approaches have been used, but generally, they all consist in the modification of platinum with a second element. Especially, bismuth has received significant attention as Pt modifier. According to the results presented in this survey dealing with the effects influencing the formic acid oxidation it was found that two types of Pt-Bi bimetallic catalysts (bulk and low loading deposits on GC showed superior catalytic activity in terms of the lower onset potential and oxidation current density, as well as exceptional stability compared to Pt. The findings in this report are important for the understanding of mechanism of formic acid electrooxidation on a bulk alloy and decorated surface, for the development of advanced anode catalysts for direct formic acid fuel cells, as well as for the synthesis of novel low-loading bimetallic catalysts. The use of bimetallic compounds as the anode catalysts is an effective solution to overcoming the problems of the formic acid oxidation current stability for long term applications. In the future, the tolerance of both CO poisoning and electrochemical leaching should be considered as the key factors in the development

  11. Aid and growth regressions

    DEFF Research Database (Denmark)

    Hansen, Henrik; Tarp, Finn

    2001-01-01

    This paper examines the relationship between foreign aid and growth in real GDP per capita as it emerges from simple augmentations of popular cross country growth specifications. It is shown that aid in all likelihood increases the growth rate, and this result is not conditional on ‘good’ policy....... There are, however, decreasing returns to aid, and the estimated effectiveness of aid is highly sensitive to the choice of estimator and the set of control variables. When investment and human capital are controlled for, no positive effect of aid is found. Yet, aid continues to impact on growth via...

  12. Aid and Development

    DEFF Research Database (Denmark)

    Tarp, Finn

    evolved since World War II in response to a dramatically changing global political and economic context. I review the aid process and associated trends in the volume and distribution of aid and categorize some of the key goals, principles and institutions of the aid system. The evidence on whether aid has......Foreign aid looms large in the public discourse; and international development assistance remains squarely on most policy agendas concerned with growth, poverty and inequality in Africa and elsewhere in the developing world. The present review takes a retrospective look at how foreign aid has...

  13. Aid and development

    DEFF Research Database (Denmark)

    Tarp, Finn

    2006-01-01

    evolved since World War II in response to a dramatically changing global political and economic context. I review the aid process and associated trends in the volume and distribution of aid and categorize some of the key goals, principles and institutions of the aid system. The evidence on whether aid has......Foreign aid looms large in the public discourse; and international development assistance remains squarely on most policy agendas concerned with growth, poverty and inequality in Africa and elsewhere in the developing world. The present review takes a retrospective look at how foreign aid has...

  14. Nanoporous PdCo Catalyst for Microfuel Cells: Electrodeposition and Dealloying

    Directory of Open Access Journals (Sweden)

    Satoshi Tominaka

    2011-01-01

    Full Text Available PdCo alloy is a promising catalyst for oxygen reduction reaction of direct methanol fuel cells because of its high activity and the tolerance to methanol. We have applied this catalyst in order to realize on-chip fuel cell which is a membraneless design. The novel design made the fuel cells to be flexible and integratable with other microdevices. Here, we summarize our recent research on the synthesis of nanostructured PdCo catalyst by electrochemical methods, which enable us to deposit the alloy onto microelectrodes of the on-chip fuel cells. First, the electrodeposition of PdCo is discussed in detail, and then, dealloying for introducing nanopores into the electrodeposits is described. Finally, electrochemical response and activities are fully discussed.

  15. Nanopore and nanoparticle catalysts.

    Science.gov (United States)

    Thomas, J M; Raja, R

    2001-01-01

    The design, atomic characterization, performance, and relevance to clean technology of two distinct categories of new nanocatalysts are described and interpreted. Exceptional molecular selectivity and high activity are exhibited by these catalysts. The first category consists of extended, crystallographically ordered inorganic solids possessing nanopores (apertures, cages, and channels), the diameters of which fall in the range of about 0.4 to about 1.5 nm, and the second of discrete bimetallic nanoparticles of diameter 1 to 2 nm, distributed more or less uniformly along the inner walls of mesoporous (ca. 3 to 10 nm diameter) silica supports. Using the principles and practices of solid-state and organometallic chemistry and advanced physico-chemical techniques for in situ and ex situ characterization, a variety of powerful new catalysts has been evolved. Apart from those that, inter alia, simulate the behavior of enzymes in their specificity, shape selectivity, regio-selectivity, and ability to function under ambient conditions, many of these new nanocatalysts are also viable as agents for effecting commercially significant processes in a clean, benign, solvent-free, single-step fashion. In particular, a bifunctional, molecular sieve nanopore catalyst is described that converts cyclohexanone in air and ammonia to its oxime and caprolactam, and a bimetallic nanoparticle catalyst that selectively converts cyclic polyenes into desirable intermediates. Nanocatalysts in the first category are especially effective in facilitating highly selective oxidations in air, and those in the second are well suited to effecting rapid and selective hydrogenations of a range of organic compounds.

  16. Hydrogen evolution reaction catalyst

    Science.gov (United States)

    Subbaraman, Ram; Stamenkovic, Vojislav; Markovic, Nenad; Tripkovic, Dusan

    2016-02-09

    Systems and methods for a hydrogen evolution reaction catalyst are provided. Electrode material includes a plurality of clusters. The electrode exhibits bifunctionality with respect to the hydrogen evolution reaction. The electrode with clusters exhibits improved performance with respect to the intrinsic material of the electrode absent the clusters.

  17. Heterogeneous chromium catalysts

    NARCIS (Netherlands)

    2005-01-01

    The present invention relates to a heterogeneous chromium catalyst system for the polymerisation of ethylene and/or alpha olefins prepared by the steps of: (a) providing a silica-containing support, (b) treating the silica-containing support with a chromium compound to form a chromium-based silica-c

  18. Deactivation of Oxidation Catalysts

    Science.gov (United States)

    1991-05-01

    Levenspiel (Reference 10) have proposed an equivalent general expression of the form dS _KST (4) dtk to account for deactivation due to catalyst pore...Voorhies, A., IEC, 1954, vol. 37, p. 318. 10. Szepe, S., and 0. Levenspiel , Proc. 4th Europ. Symp. Chem. React. Eng., Pergamon Press, p. 265. 11. U.S

  19. Olefin metathesis and catalyst

    Energy Technology Data Exchange (ETDEWEB)

    Kukes, S. G.; Banks, R. L.

    1985-05-14

    Olefins are converted into other olefins having different numbers of carbon atoms by contact with a catalyst comprising an inorganic refractory oxide support containing at least one of tungsten oxide and molybdenum oxide and a promoting amount of at least one methylating agent under conditions suitable for the methylating agent compounds to promote the activity of tungsten and molybdenum oxides for the disproportionation reaction.

  20. Catalysts for Environmental Remediation

    DEFF Research Database (Denmark)

    Abrams, B. L.; Vesborg, Peter Christian Kjærgaard

    2013-01-01

    The properties of catalysts used in environmental remediation are described here through specific examples in heterogeneous catalysis and photocatalysis. In the area of heterogeneous catalysis, selective catalytic reduction (SCR) of NOx was used as an example reaction with vanadia and tungsta...

  1. The effects of yttrium on the hydrogenation performance and surface properties of a ruthenium-supported catalyst

    Directory of Open Access Journals (Sweden)

    LAITAO LUO

    2005-12-01

    Full Text Available The effects of yttrium on the hydrogenation performance and surface properties of a Ru/sepiolite catalyst were studied. With CO2 methanation and CS2 poisoning as the testing reactons, TPR, TPD, XRD and CO chemisorption as the characterizations, the results showed that the presence of yttrium can increase the hydrogenation activity and anti-poisoning capacity of the Ru/sepiolite catalyst, which is due to a change of surface properties of the Ru/sepiolite. In the process of the catalytic reaction, the adjusting behavior of yttrium for the Ru/sepiolite catalyst aids in increasing the catalytic activity and anti-poisoning capacity of the catalyst.

  2. Molybdenum sulfide/carbide catalysts

    Science.gov (United States)

    Alonso, Gabriel; Chianelli, Russell R.; Fuentes, Sergio; Torres, Brenda

    2007-05-29

    The present invention provides methods of synthesizing molybdenum disulfide (MoS.sub.2) and carbon-containing molybdenum disulfide (MoS.sub.2-xC.sub.x) catalysts that exhibit improved catalytic activity for hydrotreating reactions involving hydrodesulfurization, hydrodenitrogenation, and hydrogenation. The present invention also concerns the resulting catalysts. Furthermore, the invention concerns the promotion of these catalysts with Co, Ni, Fe, and/or Ru sulfides to create catalysts with greater activity, for hydrotreating reactions, than conventional catalysts such as cobalt molybdate on alumina support.

  3. HIV/AIDS Coinfection

    Science.gov (United States)

    ... Laotian Mongolian Spanish Turkish Vietnamese Hindi Subscribe HIV/AIDS Coinfection Approximately 10% of the HIV-infected population ... Control and Prevention website to learn about HIV/AIDS and Viral Hepatitis guidelines and resources. Home About ...

  4. HIV/AIDS Basics

    Science.gov (United States)

    ... Partner Spotlight Awareness Days Get Tested Find an HIV testing site near you. Enter ZIP code or ... AIDS Get Email Updates on AAA Anonymous Feedback HIV/AIDS Media Infographics Syndicated Content Podcasts Slide Sets ...

  5. Neurological Complications of AIDS

    Science.gov (United States)

    ... in recent years has improved significantly because of new drugs and treatments. AIDS clinicians often fail to recognize ... in recent years has improved significantly because of new drugs and treatments. AIDS clinicians often fail to recognize ...

  6. Towards a general growth model for graphene CVD on transition metal catalysts

    Science.gov (United States)

    Cabrero-Vilatela, Andrea; Weatherup, Robert S.; Braeuninger-Weimer, Philipp; Caneva, Sabina; Hofmann, Stephan

    2016-01-01

    The chemical vapour deposition (CVD) of graphene on three polycrystalline transition metal catalysts, Co, Ni and Cu, is systematically compared and a first-order growth model is proposed which can serve as a reference to optimize graphene growth on any elemental or alloy catalyst system. Simple thermodynamic considerations of carbon solubility are insufficient to capture even basic growth behaviour on these most commonly used catalyst materials, and it is shown that kinetic aspects such as carbon permeation have to be taken into account. Key CVD process parameters are discussed in this context and the results are anticipated to be highly useful for the design of future strategies for integrated graphene manufacture.The chemical vapour deposition (CVD) of graphene on three polycrystalline transition metal catalysts, Co, Ni and Cu, is systematically compared and a first-order growth model is proposed which can serve as a reference to optimize graphene growth on any elemental or alloy catalyst system. Simple thermodynamic considerations of carbon solubility are insufficient to capture even basic growth behaviour on these most commonly used catalyst materials, and it is shown that kinetic aspects such as carbon permeation have to be taken into account. Key CVD process parameters are discussed in this context and the results are anticipated to be highly useful for the design of future strategies for integrated graphene manufacture. Electronic supplementary information (ESI) available: Fig. S1. See DOI: 10.1039/c5nr06873h

  7. Surface Structure and Catalytic Performance of Ni-Fe Catalyst for Low-Temperature CO Hydrogenation

    Directory of Open Access Journals (Sweden)

    Fanhui Meng

    2014-01-01

    Full Text Available Catalysts 16NixFe/Al2O3 (x is 0, 1, 2, 4, 6, 8 were prepared by incipient wetness impregnation method and the catalytic performance for the production of synthetic natural gas (SNG from CO hydrogenation in slurry-bed reactor were studied. The catalysts were characterized by BET, XRD, UV-Vis DRS, H2-TPR, CO-TPD, and XPS, and the results showed that the introduction of iron improved the dispersion of Ni species, weakened the interaction between Ni species and support and decreased the reduction temperature and that catalyst formed Ni-Fe alloy when the content of iron exceeded 2%. Experimental results revealed that the addition of iron to the catalyst can effectively improve the catalytic performance of low-temperature CO methanation. Catalyst 16Ni4Fe/Al2O3 with the iron content of 4% exhibited the best catalytic performance, the conversion of CO and the yield of CH4 reached 97.2% and 84.9%, respectively, and the high catalytic performance of Ni-Fe catalyst was related to the property of formed Ni-Fe alloy. Further increase of iron content led to enhancing the water gas shift reaction.

  8. Aid and growth regressions

    DEFF Research Database (Denmark)

    Hansen, Henrik; Tarp, Finn

    2001-01-01

    . There are, however, decreasing returns to aid, and the estimated effectiveness of aid is highly sensitive to the choice of estimator and the set of control variables. When investment and human capital are controlled for, no positive effect of aid is found. Yet, aid continues to impact on growth via...... investment. We conclude by stressing the need for more theoretical work before this kind of cross-country regressions are used for policy purposes....

  9. Designing State Aid Formulas

    Science.gov (United States)

    Zhao, Bo; Bradbury, Katharine

    2009-01-01

    This paper designs a new equalization-aid formula based on fiscal gaps of local communities. When states are in transition to a new local aid formula, the issue of whether and how to hold existing aid harmless poses a challenge. The authors show that some previous studies and the formulas derived from them give differential weights to existing and…

  10. Determinants of State Aid

    NARCIS (Netherlands)

    Buiren, K.; Brouwer, E.

    2010-01-01

    From economic theory we derive a set of hypotheses on the determination of state aid. Econometric analysis on EU state aid panel data is carried out to test whether the determinants we expect on the basis of theory, correspond to the occurrence of state aid in practice in the EU. We find that politi

  11. Fever: First Aid

    Science.gov (United States)

    First aid Fever: First aid Fever: First aid By Mayo Clinic Staff A fever is a rise in body temperature. It's usually a sign of infection. The ... 2 C) or higher Should I treat a fever? When you or your child is sick, the ...

  12. Stroke: First Aid

    Science.gov (United States)

    First aid Stroke: First aid Stroke: First aid By Mayo Clinic Staff A stroke occurs when there's bleeding into your brain or when normal blood flow to ... next several hours. Seek immediate medical assistance. A stroke is a true emergency. The sooner treatment is ...

  13. Aid and Development

    DEFF Research Database (Denmark)

    Tarp, Finn; Arndt, Channing; Jones, Edward Samuel

    inputs. We take as our point of departure a growth accounting analysis and review both intended and unintended effects of aid. Mozambique has benefited from sustained aid inflows in conflict, post-conflict and reconstruction periods. In each of these phases aid has made an unambiguous, positive...

  14. Synthesis and characterization of Fe–Ni/ɣ-Al2O3 egg-shell catalyst for H2 generation by ammonia decomposition

    DEFF Research Database (Denmark)

    Silva, Hugo José Lopes; Nielsen, Morten Godtfred; Fiordaliso, Elisabetta Maria

    2015-01-01

    of the active phase should match with the type of reaction. In this work, a novel synthesis route was developed for the preparation of a Fe–Ni/ɣ-Al2O3 egg-shell catalyst. Egg-shell is a preferred profile considering the highly endothermic nature of ammonia decomposition reaction. The high viscosity of glycerol......The Fe–Ni alloyed nanoparticles are a promising alternative to expensive ruthenium-based catalysts for a real-scale application of hydrogen generation by ammonia decomposition. In practical applications, millimeter-sized extrudates are used as catalyst supports, where the spatial distribution....... The outer-shell region showed the presence of Fe and Ni alloyed nanoparticles with a size of approximately 5nm.. The egg-shell catalyst showed significant higher activity in ammonia decomposition by converting 3 times more ammonia to equilibrium conversion than either egg-white or catalyst with uniform...

  15. Challenges for new electro catalysts development for the ORR in acid medium for PEM fuel cell applications

    Energy Technology Data Exchange (ETDEWEB)

    Savadogo, O. [Ecole Polytechnique, Montreal, PQ (Canada). Laboratory of New Materials for Electrochemistry and Energy

    2010-07-01

    The low kinetic rate at the oxygen reduction reaction (ORR) of platinum (Pt) electrocatalysts in acid mediums is one of the most limiting factors for the industrial mass production of proton exchange membrane fuel cells (PEMFCs). New electrocatalyst materials are currently being investigated by researchers as a replacement for Pt include lignited ruthenium-based chalcogenides; pyrolized iron (Fe) porphyrins; metal carbides; and molybdenum (Mo), iridium (Ir) and cobalt (Co) based catalysts. Co-polypyrrole is also being considered as a non-noble catalyst. This presentation discussed the main parameters that limit the ORR of non-noble catalysts in PEMFC applications. Palladium (Pa) based bi-metallic alloys were investigated. The study showed that Pd-alloy catalysts exhibit excellent activity for the ORR in acidic media. The highest electrocatalytic activity was demonstrated in an alloy composition of 60 per cent Pd. The cost of Pd was compared to the cost of Pt. The intrinsic metal surface properties of Pd-alloys were also discussed, and the onset potential of the ORR was compared for various alloys. 31 refs., 1 tab.

  16. Porous platinum-based catalysts for oxygen reduction

    Science.gov (United States)

    Erlebacher, Jonah D; Snyder, Joshua D

    2014-11-25

    A porous metal that comprises platinum and has a specific surface area that is greater than 5 m.sup.2/g and less than 75 m.sup.2/g. A fuel cell includes a first electrode, a second electrode spaced apart from the first electrode, and an electrolyte arranged between the first and the second electrodes. At least one of the first and second electrodes is coated with a porous metal catalyst for oxygen reduction, and the porous metal catalyst comprises platinum and has a specific surface area that is greater than 5 m.sup.2/g and less than 75 m.sup.2/g. A method of producing a porous metal according to an embodiment of the current invention includes producing an alloy consisting essentially of platinum and nickel according to the formula Pt.sub.xNi.sub.1-x, where x is at least 0.01 and less than 0.3; and dealloying the alloy in a substantially pH neutral solution to reduce an amount of nickel in the alloy to produce the porous metal.

  17. Fluorination process using catalysts

    Science.gov (United States)

    Hochel, R.C.; Saturday, K.A.

    1983-08-25

    A process is given for converting an actinide compound selected from the group consisting of uranium oxides, plutonium oxides, uranium tetrafluorides, plutonium tetrafluorides and mixtures of said oxides and tetrafluorides, to the corresponding volatile actinide hexafluoride by fluorination with a stoichiometric excess of fluorine gas. The improvement involves conducting the fluorination of the plutonium compounds in the presence of a fluoride catalyst selected from the group consisting of CoF/sub 3/, AgF/sub 2/ and NiF/sub 2/, whereby the fluorination is significantly enhanced. The improvement also involves conducting the fluorination of one of the uranium compounds in the presence of a fluoride catalyst selected from the group consisting of CoF/sub 3/ and AgF/sub 2/, whereby the fluorination is significantly enhanced.

  18. Fluorination process using catalyst

    Science.gov (United States)

    Hochel, Robert C.; Saturday, Kathy A.

    1985-01-01

    A process for converting an actinide compound selected from the group consisting of uranium oxides, plutonium oxides, uranium tetrafluorides, plutonium tetrafluorides and mixtures of said oxides and tetrafluorides, to the corresponding volatile actinide hexafluoride by fluorination with a stoichiometric excess of fluorine gas. The improvement involves conducting the fluorination of the plutonium compounds in the presence of a fluoride catalyst selected from the group consisting of CoF.sub.3, AgF.sub.2 and NiF.sub.2, whereby the fluorination is significantly enhanced. The improvement also involves conducting the fluorination of one of the uranium compounds in the presence of a fluoride catalyst selected from the group consisting of CoF.sub.3 and AgF.sub.2, whereby the fluorination is significantly enhanced.

  19. Photo catalyst; Ko shokubai

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1999-07-01

    While titanium oxide is excited by the light, electrons of titanium oxide are taken away by the light energy to form positive holes. Water will be decomposed into hydrogen ion and hydroxy radical (OH) by these positive holes. This hydroxy radical is a strong reactive substance called active oxygen, it decomposes organisms. Besides this photo- catalyst function, the titanium oxide can also make surface of a substance superhydrophilic. The super hydrophilicity results in not forming water drops on the glass surface but spreading all over the surface to prevent a covering of fog on the glass surface. The published patents concerning the photo catalysts were 593 from Jan. 1998 to Jan. 1999. The applicant order is the first TOTO 143, the second Daikin Industry 19, the third Toshiba Raitech, Nitto Denko, Hitachi 17 respectively. (NEDO)

  20. Olefin metathesis and catalyst

    Energy Technology Data Exchange (ETDEWEB)

    Kukes, S. G.; Banks, R. L.

    1985-03-12

    Olefins are converted into other olefins having different numbers of carbon atoms by contact with a catalyst comprising an inorganic refractory material containing at least one of tungsten oxide and molybdenum oxide and a promoting amount of at least one treating agent selected from chlorinated silicon compounds, thionyl chloride, and sulfuryl chloride under conditions suitable for the treating agent to promote the activity of tungsten and molybdenum oxides for the disporoportionation reaction.

  1. Conditional Aid Effectiveness

    DEFF Research Database (Denmark)

    Doucouliagos, Hristos; Paldam, Martin

    The AEL (aid effectiveness literature) studies the effect of development aid using econometrics on macro data. It contains about 100 papers of which a third analyzes conditional models where aid effectiveness depends upon z, so that aid only works for a certain range of the variable. The key term...... in this family of AEL models is thus an interaction term of z times aid. The leading candidates for z are a good policy index and aid itself. In this paper, meta-analysis techniques are used (i) to determine whether the AEL has established the said interaction terms, and (ii) to identify some of the determinants...... of the differences in results between studies. Taking all available studies in consideration, we find no support for conditionality with respect to policy, while conditionality regarding aid itself is dubious. However, the results differ depending on the authors’ institutional affiliation....

  2. Aid and Development

    DEFF Research Database (Denmark)

    Tarp, Finn; Arndt, Channing; Jones, Edward Samuel

    This paper considers the relationship between external aid and development in Mozambique from 1980 to 2004. The main objective is to identify the specific mechanisms through which aid has influenced the developmental trajectory of the country and whether one can plausibly link outcomes to aid...... inputs. We take as our point of departure a growth accounting analysis and review both intended and unintended effects of aid. Mozambique has benefited from sustained aid inflows in conflict, post-conflict and reconstruction periods. In each of these phases aid has made an unambiguous, positive...... contribution both enabling and supporting rapid growth since 1992. At the same time, the proliferation of donors and aid-supported interventions has burdened local administration and there is a distinct need to develop government accountability to its own citizens rather than donor agencies. In ensuring...

  3. China vs. AIDS

    Institute of Scientific and Technical Information of China (English)

    LURUCAI

    2004-01-01

    CHINA's first HIV positive diagnosis was in 1985, the victim an ArgentineAmerican. At that time most Chinese,medical workers included, thought of AIDS as a phenomenon occurring outside of China. Twenty years later, the number of HIV/AIDS patients has risen alarmingly. In 2003, the Chinese Ministry of Health launched an AIDS Epidemiological Investigation across China with the support of the WHO and UN AIDS Program. Its results show that there are currently 840,000 HIV carriers, including 80,000 people with full-blown AIDS, in 31 Chinese provinces, municipalities and autonomous regions. This means China has the second highest number of HIV/AIDS cases in Asia and 14th highest in the world. Statistics from the Chinese Venereal Disease and AIDS Prevention Association indicate that the majority of Chinese HIV carriers are young to middle aged, more than half of them between the ages of 20 and 29.

  4. Aid Effectiveness on Growth

    DEFF Research Database (Denmark)

    Doucouliagos, Hristos; Paldam, Martin

    The AEL (aid effectiveness literature) is econo¬metric studies of the macroeconomic effects of development aid. It contains about 100 papers of which 68 are reduced form estimates of theeffect of aid on growth in the recipient country. The raw data show that growth is unconnected to aid......, but the AEL has put so much structure on the data that all results possible have emerged. The present meta study considers both the best-set of the 68 papers and the all-set of 543 regressions published. Both sets have a positive average aid-growth elasticity, but it is small and insignificant: The AEL has...... betweenstudies is real. In particular, the aid-growth association is stronger for Asian countries, and the aid-growth association is shown to have been weaker in the 1970s....

  5. Supported Copper, Nickel and Copper-Nickel Nanoparticle Catalysts for Low Temperature Water-Gas-Shift Reaction

    Science.gov (United States)

    Lin, Jiann-Horng

    Hydrogen is being considered worldwide as a future replacement for gasoline, diesel fuel, natural gas in both the transportation and non-transportation sectors. Hydrogen is a versatile energy carrier that can be produced from a variety of widely available primary energy sources, including coal, natural gas, biomass, solar, wind, and nuclear power. Coal, the most abundant fossil fuel on the planet, is being looked at as the possible future major source of H2, due to the development of the integrated gasification combined cycle (IGCC) and integrated gasification fuel cell technologies (IGFC). The gasification of coal produces syngas consisting of predominately carbon monoxide and hydrogen with some remaining hydrocarbons, carbon dioxide and water. Then, the water-gas shift reaction is used to convert CO to CO2 and additional hydrogen. The present work describes the synthesis of model Cu, Ni and Cu-Ni catalysts prepared from metal colloids, and compares their behavior in the WGS reaction to that of traditional impregnation catalysts. Initially, we systematically explored the performance of traditional Cu, Ni and Cu-Ni WGS catalysts made by impregnation methods. Various bimetallic Cu-Ni catalysts were prepared by supported impregnation and compared to monometallic Cu and Ni catalysts. The presence of Cu in bimetallic catalysts suppressed undesirable methanation side reaction, while the Ni component was important for high WGS activity. Colloidal Cu, Ni and Cu-Ni alloy nanoparticles obtained by chemical reduction were deposited onto alumina to prepare supported catalysts. The resulting Cu and Ni nanoparticle catalysts were found to be 2.5 times more active in the WGS reaction per unit mass of active metal as compared to catalysts prepared by the conventional impregnation technique. The powder XRD and HAADF-STEM provided evidence supporting the formation of Cu-Ni particles containing the Cu core and Cu-Ni alloy shell. The XPS data indicated surface segregation of Cu in

  6. High-Performance Pd3Pb Intermetallic Catalyst for Electrochemical Oxygen Reduction.

    Science.gov (United States)

    Cui, Zhiming; Chen, Hao; Zhao, Mengtian; DiSalvo, Francis J

    2016-04-13

    Extensive efforts to develop highly active and strongly durable electrocatalyst for oxygen reduction are motivated by a need for metal-air batteries and fuel cells. Here, we report a very promising catalyst prototype of structurally ordered Pd-based alloys, Pd3Pb intermetallic compound. Such structurally ordered Pd3Pb/C exhibits a significant increase in mass activity. More importantly, compared to the conventional Pt/C catalysts, ordered Pd3Pb/C is highly durable and exhibits a much longer cycle life and higher cell efficiency in Zn-air batteries. Interestingly, ordered Pd3Pb/C possesses very high methanol tolerance during electrochemical oxygen reduction, which make it an excellent methanol-tolerant cathode catalyst for alkaline polymer electrolyte membrane fuel cells. This study provides a promising route to optimize the synthesis of ordered Pd-based intermetallic catalysts for fuel cells and metal-air batteries.

  7. Catalyst-nanostructure interaction in the growth of 1-D ZnO nanostructures.

    Science.gov (United States)

    Borchers, C; Müller, S; Stichtenoth, D; Schwen, D; Ronning, C

    2006-02-02

    Vapor-liquid-solid is a well-established process in catalyst guided growth of 1-D nanostructures, i.e., nanobelts and nanowires. The catalyst particle is generally believed to be in the liquid state during growth, and is the site for impinging molecules. The crystalline structure of the catalyst may not have any influence on the structure of the grown nanostructures. In this work, using Au guided growth of ZnO, we show that the interfaces between the catalyst droplet and the nanostructure grow in well-defined mutual crystallographic relationships. The nanostructure defines the crystallographic orientation of the solidifying Au droplet. Possible alloy, intermetallic, or eutectic phase formation during catalysis are elucidated with the help of a proposed ternary Au-Zn-O phase diagram.

  8. Genetic Algorithm Procreation Operators for Alloy Nanoparticle Catalysts

    DEFF Research Database (Denmark)

    Lysgaard, Steen; Landis, David Dominic; Bligaard, Thomas

    2014-01-01

    focus on the surface properties. Based on a genetic algorithm (GA) we introduce and discuss efficient permutation operations that work by interchanging positions of elements depending on their local environment and position in the cluster. We discuss the fact that in order to be efficient, the operators...... have to be dynamic, i.e. change their behavior during the course of an algorithm run. The implementation of the GA including the customized operators is freely available at http://svn.fysik.dtu. dk/projects/pga....

  9. Activity and Stability of Nanoscale Oxygen Reduction Catalysts

    Energy Technology Data Exchange (ETDEWEB)

    Shao-Horn, Yang

    2015-07-28

    Design of highly active and stable nanoscale catalysts for electro-oxidation of small organic molecules is of great importance to the development of efficient fuel cells. The amount and instability of Pt-based catalysts in the cathode limits the cost, efficiency and lifetime of proton exchange membrane fuel cells. We developed a microscopic understanding of the factors governing activity and stability in Pt and PtM alloys. Experimental efforts were focused on probing the size and shape dependence of ORR activity of Pt-based nanoparticles supported on carbon nanotubes. A microscopic understanding of the activity was achieved by correlating voltammetry and rotating ring disk electrodes to surface atomic and electronic structures, which were elucidated predominantly by high-resolution transmission electron microscopy (HRTEM), Scanning transmission electron microscopy energy dispersive X-ray Spectroscopy (STEM-EDS) and synchrotron X-ray absorption spectroscopy (XAS).

  10. Preparation of nanometer FeCuP alloy and its application in decomposition of PH3

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    A new ternary Fe-based alloy catalyst FeCuP applied to decompose PH3 was prepared with low-cost material by chemical reduction deposition method. The properties of it were characterized by XRD, ICP and SEM. Its catalytic activity on the decomposition of PH3 and the decomposition conditions were studied. FeCuP alloy exhibits high thermal stabilities and high catalytic activity. Using it as catalyst, the decomposition temperature of phosphine decreases from over 800 ℃ to 400-500 ℃. The decomposition rate of phosphine achieved 100%.

  11. Bimetallic Nanoparticles as Efficient Catalysts: Facile and Green Microwave Synthesis

    Directory of Open Access Journals (Sweden)

    Magda Blosi

    2016-07-01

    Full Text Available This work deals with the development of a green and versatile synthesis of stable mono- and bi-metallic colloids by means of microwave heating and exploiting ecofriendly reagents: water as the solvent, glucose as a mild and non-toxic reducer and polyvinylpirrolidone (PVP as the chelating agent. Particle size-control, total reaction yield and long-term stability of colloids were achieved with this method of preparation. All of the materials were tested as effective catalysts in the reduction of p-nitrophenol in the presence of NaBH4 as the probe reaction. A synergistic positive effect of the bimetallic phase was assessed for Au/Cu and Pd/Au alloy nanoparticles, the latter showing the highest catalytic performance. Moreover, monoand bi-metallic colloids were used to prepare TiO2- and CeO2-supported catalysts for the liquid phase oxidation of 5-hydroxymethylfufural (HMF to 2,5-furandicarboxylic acid (FDCA. The use of Au/Cu and Au/Pd bimetallic catalysts led to an increase in FDCA selectivity. Finally, preformed Pd/Cu nanoparticles were incorporated into the structure of MCM-41-silica. The resulting Pd/Cu MCM-41 catalysts were tested in the hydrodechlorination of CF3OCFClCF2Cl to CF3OCF=CF2. The effect of Cu on the hydrogenating properties of Pd was demonstrated.

  12. Development of GREET Catalyst Module

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Zhichao [Argonne National Lab. (ANL), Argonne, IL (United States); Benavides, Pahola T. [Argonne National Lab. (ANL), Argonne, IL (United States); Dunn, Jennifer B. [Argonne National Lab. (ANL), Argonne, IL (United States); Cronauer, Donald C. [Argonne National Lab. (ANL), Argonne, IL (United States)

    2015-09-01

    In this report, we develop energy and material flows for the production of five different catalysts (tar reforming, alcohol synthesis, Zeolite Socony Mobil-5 [ZSM-5], Mo/Co/ γ-Al2O3, and Pt/ γ-Al2O3) and two chemicals (olivine, dimethyl ether of polyethylene glycol [DEPG]). These compounds and catalysts are now included in the Greenhouse Gases, Regulated Emissions and Energy Use in Transportation (GREET™) catalyst module.

  13. Privileged chiral ligands and catalysts

    CERN Document Server

    Zhou, Qi-Lin

    2011-01-01

    This ultimate ""must have"" and long awaited reference for every chemist working in the field of asymmetric catalysis starts with the core structure of the catalysts, explaining why a certain ligand or catalyst is so successful. It describes in detail the history, the basic structural characteristics, and the applications of these ""privileged catalysts"". A novel concept that gives readers a much deeper insight into the topic.

  14. Oxygen-reducing catalyst layer

    Energy Technology Data Exchange (ETDEWEB)

    O' Brien, Dennis P. (Maplewood, MN); Schmoeckel, Alison K. (Stillwater, MN); Vernstrom, George D. (Cottage Grove, MN); Atanasoski, Radoslav (Edina, MN); Wood, Thomas E. (Stillwater, MN); Yang, Ruizhi (Halifax, CA); Easton, E. Bradley (Halifax, CA); Dahn, Jeffrey R. (Hubley, CA); O' Neill, David G. (Lake Elmo, MN)

    2011-03-22

    An oxygen-reducing catalyst layer, and a method of making the oxygen-reducing catalyst layer, where the oxygen-reducing catalyst layer includes a catalytic material film disposed on a substrate with the use of physical vapor deposition and thermal treatment. The catalytic material film includes a transition metal that is substantially free of platinum. At least one of the physical vapor deposition and the thermal treatment is performed in a processing environment comprising a nitrogen-containing gas.

  15. Catalyst systems and uses thereof

    Science.gov (United States)

    Ozkan, Umit S.; Holmgreen, Erik M.; Yung, Matthew M.

    2012-07-24

    A method of carbon monoxide (CO) removal comprises providing an oxidation catalyst comprising cobalt supported on an inorganic oxide. The method further comprises feeding a gaseous stream comprising CO, and oxygen (O.sub.2) to the catalyst system, and removing CO from the gaseous stream by oxidizing the CO to carbon dioxide (CO.sub.2) in the presence of the oxidation catalyst at a temperature between about 20 to about 200.degree. C.

  16. Translating VDM to Alloy

    DEFF Research Database (Denmark)

    Lausdahl, Kenneth

    2013-01-01

    . Traditionally, theorem provers are used to prove that specifications are correct but this process is highly dependent on expert users. Alternatively, model finding has proved to be useful for validation of specifications. The Alloy Analyzer is an automated model finder for checking and visualising Alloy...... specifications. However, to take advantage of the automated analysis of Alloy, the model-oriented VDM specifications must be translated into a constraint-based Alloy specifications. We describe how a sub- set of VDM can be translated into Alloy and how assertions can be expressed in VDM and checked by the Alloy...

  17. Bimetallic Au-decorated Pd catalyst for the liquid phase hydrodechlorination of 2,4-dichlorophenol

    Energy Technology Data Exchange (ETDEWEB)

    Zhou, Juan [School of the Environment, Donghua University, Shanghai 201620 (China); Chen, Huan, E-mail: hchen404@njust.edu.cn [Key Laboratory of Jiangsu Province for Chemical Pollution Control and Resources Reuse, School of Environmental & Biological Engineering, Nanjing University of Science and Technology, Nanjing 210094 (China); Chen, Quanyuan; Huang, Zhaolu [School of the Environment, Donghua University, Shanghai 201620 (China)

    2016-11-30

    Graphical abstract: 2,4-Dichlorophenol can be converted to phenol via the catalytic HDC method over Pd-Au/CNTs and the catalytic activity first increased and then decreased with Au content. - Highlights: • Bimetallic catalysts had smaller metal particles and larger number of exposed active site than the monometallic catalysts. • The cationization of Pd particles increased with Au content in the bimetallic catalysts. • The bimetallic catalysts exhibited higher catalytic activities for HDC of 2,4-DCP than the monometallic counterparts. • The concerted pathway for HDC of 2,4-DCP was more predominant with increasing Au content in the bimetallic catalyst. - Abstract: Monometallic and bimetallic Pd-Au catalysts supported on multi-walled carbon nanotubes (CNTs) with varied Au cooperation amounts were prepared using the complexing-reduction method in the presence of tetrahydrofuran (THF). The liquid phase catalytic hydrodechlorination (HDC) of 2,4-dichlorophenol (2,4-DCP) was investigated over these bimetallic catalysts. The catalysts were characterized by N{sub 2} adsorption-desorption isotherms, X-ray diffraction, transmission electron microscopy, X-ray photoelectron spectroscopy, and H{sub 2} chemisorption. Characterization results showed that the co-reduction of Pd and Au mainly formed alloy-like structure. The bimetallic catalysts had smaller metal particles and larger numbers of exposed active site than that of monometallic catalysts. In addition, compared with Pd(1.7)/CNTs and Au(0.4)/CNTs, the binding energies of Pd 3d{sub 5/2} shifted to higher positions while that of Au 4f{sub 7/2} had negative shifts in the Pd-Au bimetallic catalysts, which can be ascribed to the electrons transferred from metal Pd to Au and the cationization of Pd particles was enhanced. Accordingly, the bimetallic Pd-Au particles with different Au contents in the catalysts exhibited varied synergistic effects for the catalytic HDC of 2,4-DCP, with Pd(1.8)Au(0.4)/CNTs having the highest

  18. Surface segregations in platinum-based alloy nanoparticles

    Science.gov (United States)

    Yamakawa, Shunsuke; Asahi, Ryoji; Koyama, Toshiyuki

    2014-04-01

    A phase-field model that describes the radial distributions of the ordered-disordered phase and surface segregation in a single-alloy nanoparticle is introduced to clarify the overall behavior of surface segregation of various Pt-based alloy nanoparticles. One of the obstacles to apply a platinum-transition metal alloy as a cathode electro-catalyst of a polymer electrolyte fuel cell is the need to ensure the retention of the designed surface composition in an alloy nanoparticle against the alloy combinations, a particle size, and heat treatment. From the results of calculations for CrPt, FePt, CoPt, NiPt, CuPt, PdPt, IrPt, and AuPt binary nanoparticles with diameters below 10 nm at 973.15 K, the compositional variation within a single particle was found to depend on the balance between the atomic interaction within particles and the surface free energy. In addition, the obtained specific steady-state composition of the surface varied significantly with alloy combination and particle diameter. Based on the general tendencies of a binary system to exhibit segregation, attempts to control the amount of platinum segregation on the surface using a ternary-alloy system were examined.

  19. Electrodeposition of PdCu alloy and its application in methanol electro-oxidation

    Energy Technology Data Exchange (ETDEWEB)

    Hsieh, Ming-Wei [Department of Chemistry, National Cheng Kung University, 1 University Road, Tainan 70101, Taiwan (China); Whang, Thou-Jen, E-mail: twhang@mail.ncku.edu.tw [Department of Chemistry, National Cheng Kung University, 1 University Road, Tainan 70101, Taiwan (China)

    2013-04-01

    This study demonstrates a simple electrodeposition method to fabricate the palladium–copper alloy on an ITO coated glass (PdCu/ITO) and its application in methanol electro-oxidation. Our approaches involve the co-reduction of Pd and Cu using triethanolamine (TEA) as a complexing agent in the electroplating bath and a Pd redox replacement of Cu on the surface of the as-prepared PdCu alloy. The phase structures, alloy compositions and morphologies of catalysts are determined by X-ray diffraction, energy dispersive spectrometer and scanning electron microscopy, respectively. X-ray diffraction shows that the particle size of PdCu deposits shrink when the alloy is deposited in a TEA-contained solution. The electrocatalytic properties of PdCu alloys and Pd redox replacement modified PdCu alloys for methanol oxidation have been investigated by cyclic voltammetry. The PdCu alloy with atomic ratio of 20.5% Cu exhibits higher catalytic activity toward methanol oxidation compared with a pure Pd catalyst. PdCu alloys with smaller particle sizes associated with TEA agent and the surface confined Pd replacement are found to have enhanced catalytic performance in the electro-oxidation of methanol.

  20. Aid and Growth

    DEFF Research Database (Denmark)

    Arndt, Channing; Jones, Edward Samuel; Tarp, Finn

    The micro-macro paradox has been revived. Despite broadly positive evaluations at the micro and meso-levels, recent literature has turned decidedly pessimistic with respect to the ability of foreign aid to foster economic growth. Policy implications, such as the complete cessation of aid to Africa......, are being drawn on the basis of fragile evidence. This paper first assesses the aid-growth literature with a focus on recent contributions. The aid-growth literature is then framed, for the first time, in terms of the Rubin Causal Model, applied at the macroeconomic level. Our results show that aid has...... a positive and statistically significant causal effect on growth over the long run with point estimates at levels suggested by growth theory. We conclude that aid remains an important tool for enhancing the development prospects of poor nations....

  1. Aid and Growth

    DEFF Research Database (Denmark)

    Arndt, Channing; Jones, Edward Samuel; Tarp, Finn

    2009-01-01

    The micro-macro paradox has been revived. Despite broadly positive evaluations at the micro and meso-levels, recent literature has turned decidedly pessimistic with respect to the ability of foreign aid to foster economic growth. Policy implications, such as the complete cessation of aid to Africa......, are being drawn on the basis of fragile evidence. This paper first assesses the aid-growth literature with a focus on recent contributions. The aid-growth literature is then framed, for the first time, in terms of the Rubin Causal Model, applied at the macroeconomic level. Our results show that aid has...... a positive and statistically significant causal effect on growth over the long run with point estimates at levels suggested by growth theory. We conclude that aid remains an important tool for enhancing the development prospects of poor nations....

  2. Bimetallic Au-decorated Pd catalyst for the liquid phase hydrodechlorination of 2,4-dichlorophenol

    Science.gov (United States)

    Zhou, Juan; Chen, Huan; Chen, Quanyuan; Huang, Zhaolu

    2016-11-01

    Monometallic and bimetallic Pd-Au catalysts supported on multi-walled carbon nanotubes (CNTs) with varied Au cooperation amounts were prepared using the complexing-reduction method in the presence of tetrahydrofuran (THF). The liquid phase catalytic hydrodechlorination (HDC) of 2,4-dichlorophenol (2,4-DCP) was investigated over these bimetallic catalysts. The catalysts were characterized by N2 adsorption-desorption isotherms, X-ray diffraction, transmission electron microscopy, X-ray photoelectron spectroscopy, and H2 chemisorption. Characterization results showed that the co-reduction of Pd and Au mainly formed alloy-like structure. The bimetallic catalysts had smaller metal particles and larger numbers of exposed active site than that of monometallic catalysts. In addition, compared with Pd(1.7)/CNTs and Au(0.4)/CNTs, the binding energies of Pd 3d5/2 shifted to higher positions while that of Au 4f7/2 had negative shifts in the Pd-Au bimetallic catalysts, which can be ascribed to the electrons transferred from metal Pd to Au and the cationization of Pd particles was enhanced. Accordingly, the bimetallic Pd-Au particles with different Au contents in the catalysts exhibited varied synergistic effects for the catalytic HDC of 2,4-DCP, with Pd(1.8)Au(0.4)/CNTs having the highest catalytic activity. For the bimetallic catalysts, a disproportional increase of turnover frequency (TOF) was observed with increasing Au content due to the enhanced cationization of Pd particles. Moreover, the dechlorination of 2,4-DCP over the supported monometallic and bimetallic catalysts proceeded via both the stepwise and concerted pathway, and the concerted pathway became predominant with Au decoration amount in the catalyst.

  3. Effects of promoters on catalytic performance of Fe-Co/SiO_2 catalyst for Fischer-Tropsch synthesis

    Institute of Scientific and Technical Information of China (English)

    Xiangdong Ma; Qiwen Sun; Weiyong Ying; Dingye Fang

    2009-01-01

    2%Fe-10%Co/SiO_2 catalysts with different potassium or zirconium Ioadings were prepared by aqueous incipient wetness impregnation and tested for Fischer-Tropsch synthesis in a flow reactor,using H_2/CO = 1.6 (molar ratio) in the feed,under the condition of an overall pressure of 1 MPa,GHSV of 600 h~(-1) and temperature of 503 K. The zirconium and potassium promoters remarkably influenced hydrocarbon distribution of the products. CO conversion increased on the catalysts with the increase of zirconium loadings,which indicated that zirconium enhanced the activity of iron-cobalt catalysts. Low potassium Ioadings also enhanced the activity of the catalysts. However,high potassium loading made CO conversion on the catalysts decrease and weakened the secondary hydrogenations. The catalyst was characterized by BET,XRD and TPR. The catalyst characterization revealed that the Co_3O_4 phase was presented on the fresh catalyst,whereas the spinel phase of Fe-Co alloy and CoO existed on the used catalyst.

  4. AIDS in South Africa.

    Science.gov (United States)

    Ijsselmuiden, C; Evian, C; Matjilla, J; Steinberg, M; Schneider, H

    1993-01-01

    The National AIDS Convention in South Africa (NACOSA) in October 1992 was the first real attempt to address HIV/AIDS. In Soweto, government, the African National Congress, nongovernmental organizations, and organized industry and labor representatives worked for 2 days to develop a national plan of action, but it did not result in a united effort to fight AIDS. The highest HIV infection rates in South Africa are among the KwaZulu in Natal, yet the Inkatha Freedom Party did not attend NACOSA. This episode exemplifies the key obstacles for South Africa to prevent and control AIDS. Inequality of access to health care may explain why health workers did not diagnose the first AIDS case in blacks until 1985. Migrant labor, Bantu education, and uprooted communities affect the epidemiology of HIV infection. Further, political and social polarization between blacks and whites contributes to a mindset that AIDS is limited to the other race which only diminishes the personal and collective sense of susceptibility and the volition and aptitude to act. The Department of National Health and Population Development's voluntary register of anonymously reported cases of AIDS specifies 1517 cumulative AIDS cases (October 1992), but this number is low. Seroprevalence studies show between 400,000-450,000 HIV positive cases. Public hospitals cannot give AIDS patients AZT and DDI. Few communities provided community-based care. Not all hospitals honor confidentiality and patients' need for autonomy. Even though HIV testing is not mandatory, it is required sometimes, e.g., HIV testing of immigrants. AIDS Training, Information and Counselling Centers are in urban areas, but not in poor areas where the need is most acute. The government just recently developed in AIDS education package for schools, but too many people consider it improper, so it is not being used. The poor quality education provided blacks would make it useless anyhow. Lifting of the academic boycott will allow South African

  5. JPRS Report, Epidemiology, Aids

    Science.gov (United States)

    2007-11-02

    at home. For this they can thank the National Federation of Gays and Lesbians (LBL). -To develop an adequate core of specialists in AIDS prevention... Homosexuality [Vusie Ginindza; Mbabane THE TIMES OF SWAZILAND, 15 May 91] ...................................... 4 JPRS-TEP-91-012 5 June 1991 2 AIDS TANZANIA...sensitivity and not to sensa- tionalize the issue. Health Workers ’Alarmed’ at rise in AIDS, Homosexuality SWAZILAND MB1505085891 Mbabane THE TIMES

  6. Radiographic imaging of aids

    CERN Document Server

    Mahmoud, M B

    2002-01-01

    The acquired immunodeficiency syndrome (AIDS) has impacted the civilized world like no other disease. This research aimed to discuss some of the main aids-related complications and their detection by radiology tests, specifically central nervous system and musculoskeletal system disorders. The objectives are: to show specific characteristics of various diseases of HIV patient, to analyze the effect of pathology in patients by radiology, to enhance the knowledge of technologists in aids imaging and to improve communication skills between patient and radiology technologists.

  7. High-performance PdRu bimetallic catalyst supported on mesoporous silica nanoparticles for phenol hydrogenation

    Energy Technology Data Exchange (ETDEWEB)

    Huang, Chao [The Key Laboratory of Fuel Cell Technology of Guangdong Province and The Key Laboratory for New Energy of Guangdong Universities, School of Chemistry and Chemical Engineering, South China University of Technology, Guangzhou (China); Yang, Xu [Key Laboratory of Renewable Energy, Guangzhou Institute of Energy Conversion, Chinese Academy of Sciences, Guangzhou (China); Yang, Hui; Huang, Peiyan; Song, Huiyu [The Key Laboratory of Fuel Cell Technology of Guangdong Province and The Key Laboratory for New Energy of Guangdong Universities, School of Chemistry and Chemical Engineering, South China University of Technology, Guangzhou (China); Liao, Shijun, E-mail: chsjliao@scut.edu.cn [The Key Laboratory of Fuel Cell Technology of Guangdong Province and The Key Laboratory for New Energy of Guangdong Universities, School of Chemistry and Chemical Engineering, South China University of Technology, Guangzhou (China)

    2014-10-01

    Graphical abstract: The addition of Ru could significantly improve the performance of the mesoporous silica nanoparticles supported PdRu/MSN catalyst, which showed over 5 times higher mass activity than the mono-Pd/MSN towards the liquid-phase hydrogenation of phenol. The improved dispersion and the electronic interaction contributed to the enhanced catalytic activity for the catalyst towards phenol hydrogenation. - Highlights: • PdRu bimetal catalyst supported on mesoporous silica nanoparticles was prepared. • The average sizeof PdRu alloy is smaller than that of mono-Pd. • The addition of Ru to Pd modulates the electronic properties between Pd and Ru. • PdRu/MSN catalyst shows superior activity on phenol hydrogenation than Pd/MSN. • PdRu/MSN catalyst shows good selectivity for cyclohexanol to some extent. - Abstract: A high-performance PdRu bimetallic catalyst supported on mesoporous silica nanoparticles (MSN), PdRu/MSN, was prepared by a facile impregnation–hydrogen reduction method. It was found that PdRu/MSN showed 5 times higher activity than that of Pd/MSN towards the liquid-phase hydrogenation of phenol. The catalysts were characterized comprehensively by multiple techniques, X-ray diffraction (XRD), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), and hydrogen temperature program reduction (TPR). It was revealed that adding Ru could effectively improve the Pd dispersion and promote the electronic interaction between the Pd and Ru, both of which contribute to enhancing the catalytic activity.

  8. REACTOR FILLED WITH CATALYST MATERIAL, AND CATALYST THEREFOR

    NARCIS (Netherlands)

    Sie, S.T.

    1995-01-01

    Abstract of WO 9521691 (A1) Described is a reactor (1) at least partially filled with catalyst granules (11), which is intended for catalytically reacting at least one gas and at least one liquid with each other. According to the invention the catalyst granules (11) are collected in agglomerates

  9. Music and hearing aids.

    Science.gov (United States)

    Madsen, Sara M K; Moore, Brian C J

    2014-10-31

    The signal processing and fitting methods used for hearing aids have mainly been designed to optimize the intelligibility of speech. Little attention has been paid to the effectiveness of hearing aids for listening to music. Perhaps as a consequence, many hearing-aid users complain that they are not satisfied with their hearing aids when listening to music. This issue inspired the Internet-based survey presented here. The survey was designed to identify the nature and prevalence of problems associated with listening to live and reproduced music with hearing aids. Responses from 523 hearing-aid users to 21 multiple-choice questions are presented and analyzed, and the relationships between responses to questions regarding music and questions concerned with information about the respondents, their hearing aids, and their hearing loss are described. Large proportions of the respondents reported that they found their hearing aids to be helpful for listening to both live and reproduced music, although less so for the former. The survey also identified problems such as distortion, acoustic feedback, insufficient or excessive gain, unbalanced frequency response, and reduced tone quality. The results indicate that the enjoyment of listening to music with hearing aids could be improved by an increase of the input and output dynamic range, extension of the low-frequency response, and improvement of feedback cancellation and automatic gain control systems.

  10. Mechanochemistry, catalysis, and catalysts

    Energy Technology Data Exchange (ETDEWEB)

    Butyagin, P.Yu.

    1987-07-01

    The physical basis of mechanochemistry and the reasons for the initiation and acceleration of chemical reactions upon the mechanical treatment of solids have been considered. The phenomenon of mechanical catalysis has been described in the example case of the oxidation of CO on oxide surfaces, and the nature of the active sites and the laws governing the mechanically activated chemisorption of gases on cleavage and friction surfaces of solids have been examined. The possibilities of the use of the methods of mechanochemistry in processes used to prepare catalysts have been analyzed in examples of decomposition reactions of inorganic compounds and solid-phase synthesis.

  11. In-situ characterization of heterogeneous catalysts

    CERN Document Server

    Rodriguez, Jose A; Chupas, Peter J

    2013-01-01

    Helps researchers develop new catalysts for sustainable fuel and chemical production Reviewing the latest developments in the field, this book explores the in-situ characterization of heterogeneous catalysts, enabling readers to take full advantage of the sophisticated techniques used to study heterogeneous catalysts and reaction mechanisms. In using these techniques, readers can learn to improve the selectivity and the performance of catalysts and how to prepare catalysts as efficiently as possible, with minimum waste. In-situ Characterization of Heterogeneous Catalysts feat

  12. Preparation and characterization of nano-sized Pt-Ru/C catalysts and their superior catalytic activities for methanol and ethanol oxidation.

    Science.gov (United States)

    Şen, Selda; Şen, Fatih; Gökağaç, Gülsün

    2011-04-21

    Carbon-supported PtRu nanoparticles (Ru/Pt: 0.25) were prepared by three different methods; simultaneous reduction of PtCl(4) and RuCl(3) (catalyst I) and changing the reduction order of PtCl(4) and RuCl(3) (catalysts II and III) to enhance the performance of the anodic catalysts for methanol and ethanol oxidation. Structure, microstructure and surface characterizations of all the catalysts were carried out by X-ray diffraction (XRD), transmission electron microscopy (TEM) coupled with energy dispersive X-ray spectroscopy (EDS) and X-ray photoelectron spectroscopy (XPS). The results of the XRD analysis showed that all catalysts had a face-centered cubic (fcc) structure with different and smaller lattice parameters than that of pure platinum, showing that the Ru incorporates into the Pt fcc structure by different ratios in all the catalysts. The typical particle sizes of all catalysts were in the range of 2-3 nm. The most active and stable catalyst for methanol and ethanol oxidation is catalyst III, in which a large amount (more than 90%) of PtRu alloy formation was observed. It has been found that this catalyst is about 8.0 and 33.4 times more active at ∼0.60 V towards the methanol and ethanol oxidation reactions, respectively, compared to the commercial Pt catalyst.

  13. Alloy Fabrication Laboratory

    Data.gov (United States)

    Federal Laboratory Consortium — At NETL’s Alloy Fabrication Facility in Albany, OR, researchers conduct DOE research projects to produce new alloys suited to a variety of applications, from gas...

  14. Platinum and palladium nano-structured catalysts for polymer electrolyte fuel cells and direct methanol fuel cells.

    Science.gov (United States)

    Long, Nguyen Viet; Thi, Cao Minh; Yong, Yang; Nogami, Masayuki; Ohtaki, Michitaka

    2013-07-01

    In this review, we present the synthesis and characterization of Pt, Pd, Pt based bimetallic and multi-metallic nanoparticles with mixture, alloy and core-shell structure for nano-catalysis, energy conversion, and fuel cells. Here, Pt and Pd nanoparticles with modified nanostructures can be controllably synthesized via chemistry and physics for their uses as electro-catalysts. The cheap base metal catalysts can be studied in the relationship of crystal structure, size, morphology, shape, and composition for new catalysts with low cost. Thus, Pt based alloy and core-shell catalysts can be prepared with the thin Pt and Pt-Pd shell, which are proposed in low and high temperature proton exchange membrane fuel cells (PEMFCs), and direct methanol fuel cells (DMFCs). We also present the survey of the preparation of Pt and Pd based catalysts for the better catalytic activity, high durability, and stability. The structural transformations, quantum-size effects, and characterization of Pt and Pd based catalysts in the size ranges of 30 nm (1-30 nm) are presented in electro-catalysis. In the size range of 10 nm (1-10 nm), the pure Pt catalyst shows very large surface area for electro-catalysis. To achieve homogeneous size distribution, the shaped synthesis of the polyhedral Pt nanoparticles is presented. The new concept of shaping specific shapes and morphologies in the entire nano-scale from nano to micro, such as polyhedral, cube, octahedra, tetrahedra, bar, rod, and others of the nanoparticles is proposed, especially for noble and cheap metals. The uniform Pt based nanosystems of surface structure, internal structure, shape, and morphology in the nanosized ranges are very crucial to next fuel cells. Finally, the modifications of Pt and Pd based catalysts of alloy, core-shell, and mixture structures lead to find high catalytic activity, durability, and stability for nano-catalysis, energy conversion, fuel cells, especially the next large-scale commercialization of next

  15. Latent catalyst; Senzaisei shokubai

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    2000-03-01

    Epoxy resin, an important function material to support such main industries as electric and electronic devices, automobiles, civil engineering, and building construction, is demanded of development of single liquid type resin having excellent quick hardening performance and storage stability. This requirement comes from environmental problems with an intention of saving energies and reducing resin wastes. The Company, using freely its independent phase separation technology that controls molecular structure of catalysts, developed a latent catalyst having excellent storage stability and high-temperature quick hardening performance. Its major features may be summarized as follows: (1) excellent storage stability at room temperature keeping the product stable for 2.5 months or longer (2 days in conventional products); (2) quick hardening performance hardening the resin in seven seconds at 150 degrees C (equivalent to conventional products); and (3) excellent insulation performance of hardened resin at 140 degrees C of 7 times 10 {sup 13} (ohm) (center dot) cm (2 times 10 {sup 12} (ohm) (center dot) cm in conventional products) (translated by NEDO)

  16. Catalyst design for biorefining.

    Science.gov (United States)

    Wilson, Karen; Lee, Adam F

    2016-02-28

    The quest for sustainable resources to meet the demands of a rapidly rising global population while mitigating the risks of rising CO2 emissions and associated climate change, represents a grand challenge for humanity. Biomass offers the most readily implemented and low-cost solution for sustainable transportation fuels, and the only non-petroleum route to organic molecules for the manufacture of bulk, fine and speciality chemicals and polymers. To be considered truly sustainable, biomass must be derived from resources which do not compete with agricultural land use for food production, or compromise the environment (e.g. via deforestation). Potential feedstocks include waste lignocellulosic or oil-based materials derived from plant or aquatic sources, with the so-called biorefinery concept offering the co-production of biofuels, platform chemicals and energy; analogous to today's petroleum refineries which deliver both high-volume/low-value (e.g. fuels and commodity chemicals) and low-volume/high-value (e.g. fine/speciality chemicals) products, thereby maximizing biomass valorization. This article addresses the challenges to catalytic biomass processing and highlights recent successes in the rational design of heterogeneous catalysts facilitated by advances in nanotechnology and the synthesis of templated porous materials, as well as the use of tailored catalyst surfaces to generate bifunctional solid acid/base materials or tune hydrophobicity.

  17. F-Alloy: An Alloy Based Model Transformation Language

    OpenAIRE

    Gammaitoni, Loïc; Kelsen, Pierre

    2015-01-01

    Model transformations are one of the core artifacts of a model-driven engineering approach. The relational logic language Alloy has been used in the past to verify properties of model transformations. In this paper we introduce the concept of functional Alloy modules. In essence a functional Alloy module can be viewed as an Alloy module representing a model transformation. We describe a sublanguage of Alloy called F-Alloy that allows the specification of functional Alloy modules. Module...

  18. PLUTONIUM-THORIUM ALLOYS

    Science.gov (United States)

    Schonfeld, F.W.

    1959-09-15

    New plutonium-base binary alloys useful as liquid reactor fuel are described. The alloys consist of 50 to 98 at.% thorium with the remainder plutonium. The stated advantages of these alloys over unalloyed plutonium for reactor fuel use are easy fabrication, phase stability, and the accompanying advantuge of providing a means for converting Th/sup 232/ into U/sup 233/.

  19. Hydrogenation of Furfural to Furfuryl Alcohol over Co-B Amorphous Catalysts Prepared by Chemical Reduction in Variable Media

    Institute of Scientific and Technical Information of China (English)

    LI, Hui; CHAI, Wei-Mei; LUO, Hong-Shan; LI, He-Xing

    2006-01-01

    Five Co-B amorphous alloy catalysts were prepared by chemical reduction in different media, including pure water and pure ethanol as well as the mixture of ethanol and water with variable ethanol content. Their catalytic properties were evaluated using liquid phase furfural hydrogenation to furfuryl alcohol as the probe reaction. It was found that the reaction media had no significant influence on either the amorphous structure of the Co-B catalyst or the electronic interaction between metallic Co and alloying B. This could successfully account for the fact that all the as-prepared Co-B catalysts exhibited almost the same selectivity to furfuryl alcohol and the same activity per surface area ( RSH ), which could be considered as the intrinsic activity, since the nature of active sites remained unchanged. However, the activity per gram of Co ( RmH ) of the as-prepared Co-B catalysts increased rapidly when the ethanol content in the water-ethanol mixture used as the reaction medium for catalyst preparation increased. This could be attributed to the rapid increase in the surface area possibly owing to the presence of more oxidized boron species which could serve as a support for dispersing the Co-B amorphous alloy particles.

  20. Magnetic Implants Aid Hearing

    Institute of Scientific and Technical Information of China (English)

    陈宏

    1995-01-01

    The next generation of hearing aids may use tiny magnets that fit inside the ear. Researchersat a California company and an engineer at the University of Virginia are both developing systems that rely on magnets to convey sounds. Conventional hearing aids have three components:a microphone, an amplifier, and a speaker. The microphone picks up sounds and sends them to the am-

  1. Genetic Immunity to AIDS

    Institute of Scientific and Technical Information of China (English)

    2005-01-01

    In an article on genetic immunity to AIDS published in Science magazine, American and Chinese scientists claim to have discovered why certain HIV carriers do not develop full-blown AIDS. They say that the key to this conundrum lies in a particular protein in the endocrine system that inhibits development of HIV.

  2. Aid and sectoral growth

    DEFF Research Database (Denmark)

    Selaya, Pablo; Thiele, Rainer

    2010-01-01

    This article examines empirically the proposition that aid to poor countries is detrimental for external competitiveness, giving rise to Dutch disease type effects. At the aggregate level, aid is found to have a positive effect on growth. A sectoral decomposition shows that the effect is (i...

  3. International Aid to Education

    Science.gov (United States)

    Benavot, Aaron

    2010-01-01

    Recent evidence highlights several worrisome trends regarding aid pledges and disbursements, which have been exacerbated by the global financial crisis. First, while overall development assistance rose in 2008, after 2 years of decline, the share of all sector aid going to the education sector has remained virtually unchanged at about 12 percent…

  4. AIDS Epidemiological models

    Science.gov (United States)

    Rahmani, Fouad Lazhar

    2010-11-01

    The aim of this paper is to present mathematical modelling of the spread of infection in the context of the transmission of the human immunodeficiency virus (HIV) and the acquired immune deficiency syndrome (AIDS). These models are based in part on the models suggested in the field of th AIDS mathematical modelling as reported by ISHAM [6].

  5. Aid and Income

    DEFF Research Database (Denmark)

    Lof, Matthijs; Mekasha, Tseday Jemaneh; Tarp, Finn

    2015-01-01

    to nonrandom omission of a large proportion of observations. Furthermore, we show that NDHKM’s use of co-integrated regressions is not a suitable empirical strategy for estimating the causal effect of aid on income. Evidence from a Panel VAR model estimated on the dataset of NDHKM, suggests a positive...... and statistically significant long-run effect of aid on income....

  6. First Aid: Burns

    Science.gov (United States)

    ... Your 1- to 2-Year-Old First Aid: Burns KidsHealth > For Parents > First Aid: Burns A A A Scald burns from hot water and other liquids are the most common burns in early childhood. Because burns range from mild ...

  7. The Aid Effectiveness Literature

    DEFF Research Database (Denmark)

    Doucouliagos, Hristos; Paldam, Martin

    The AEL consists of empirical macro studies of the effects of development aid. At the end of 2004 it had reached 97 studies of three families, which we have summarized in one study each using meta-analysis. Studies of the effect on investments show that they rise by 1/3 of the aid – the rest is c...

  8. First Aid: Diaper Rash

    Science.gov (United States)

    ... Your 1- to 2-Year-Old First Aid: Diaper Rash KidsHealth > For Parents > First Aid: Diaper Rash A A A Diaper rash is a common skin condition in babies. ... rash is due to irritation caused by the diaper, but it can have other causes not related ...

  9. First Aid: Burns

    Science.gov (United States)

    ... Old Feeding Your 8- to 12-Month-Old Feeding Your 1- to 2-Year-Old First Aid: Burns KidsHealth > For Parents > First Aid: Burns Print A A A Scald burns from hot water and other liquids are the most common burns in early childhood. Because burns range from mild to life threatening, ...

  10. Aid, Development, and Education

    Science.gov (United States)

    Klees, Steven J.

    2010-01-01

    The world faces pervasive poverty and inequality. Hundreds of billions of dollars in international aid have been given or loaned to developing countries though bilateral and multilateral mechanisms, at least, ostensibly, in order to do something about these problems. Has such aid helped? Debates around this question have been ongoing for decades,…

  11. HIV and AIDS

    Science.gov (United States)

    ... one HIV test by the time they are teens. If you are having sex, have had sex in the past, or shared ... reviewed: October 2015 previous 1 • 2 • ... STDs How Do People Get AIDS? Can You Get HIV From Having Sex With Someone Who Has AIDS? Can Someone Get ...

  12. First Aid: Falls

    Science.gov (United States)

    ... Your 1- to 2-Year-Old First Aid: Falls KidsHealth > For Parents > First Aid: Falls Print A A A en español Folleto de instructiones: Caídas (Falls) With all the running, climbing, and exploring kids ...

  13. AIDS as Metaphor.

    Science.gov (United States)

    McMillen, Liz

    1994-01-01

    Scholarly interest in Acquired Immune Deficiency Syndrome (AIDS) has spread throughout the humanities, attracting the attention of historians of medicine, political scientists, sociologists, public health scholars, and anthropologists. Most theorists hope their research will aid in policymaking or change understanding of the epidemic. (MSE)

  14. Active and Durable Hydrogen Evolution Reaction Catalyst Derived from Pd-Doped Metal-Organic Frameworks.

    Science.gov (United States)

    Chen, Jitang; Xia, Guoliang; Jiang, Peng; Yang, Yang; Li, Ren; Shi, Ruohong; Su, Jianwei; Chen, Qianwang

    2016-06-01

    The water electrolysis is of critical importance for sustainable hydrogen production. In this work, a highly efficient and stable PdCo alloy catalyst (PdCo@CN) was synthesized by direct annealing of Pd-doped metal-organic frameworks (MOFs) under N2 atmosphere. In 0.5 M H2SO4 solution, PdCo@CN displays remarkable electrocatalytic performance with overpotential of 80 mV, a Tafel slope of 31 mV dec(-1), and excellent stability of 10 000 cycles. Our studies reveal that noble metal doped MOFs are ideal precursors for preparing highly active alloy electrocatalysts with low content of noble metal.

  15. Final technical report. Bimetallic complexes as methanol oxidation catalysts

    Energy Technology Data Exchange (ETDEWEB)

    McElwee-White, Lisa

    2002-01-21

    Our work on the electrocatalyzed oxidation of methanol was initially motivated by the interest in methanol as an anodic reactant in fuel cells. The literature on electrochemical oxidation of alcohols can be roughly grouped into two sets: fuel cell studies and inorganic chemistry studies. Work on fuel cells primarily focuses on surface-catalyzed oxidation at bulk metal anodes, usually Pt or Pt/Ru alloys. In the surface science/electrochemistry approach to these studies, single molecule catalysts are generally not considered. In contrast, the inorganic community investigates the electrooxidation of alcohols in homogeneous systems. Ruthenium complexes have been the most common catalysts in these studies. The alcohol substrates are typically either secondary alcohols (e.g., isopropanol) such that the reaction stops after 2 e{sup -} oxidation to the aldehyde and 4 e{sup -} oxidation to the carboxylic acid can be observed. Methanol, which can also undergo 6 e{sup -} oxidation to CO{sub 2}, rarely appears in the homogeneous catalysis studies. Surface studies have shown that two types of metal centers with different functions result in more effective catalysts than a single metal; however, application of this concept to homogeneous systems has not been demonstrated. The major thrust of the work is to apply this insight from the surface studies to homogeneous catalysis. Even though homogeneous systems would not be appropriate models for active sites on Pt/Ru anodes, it is possible that heterobimetallic catalysts could also utilize two metal centers for different roles. Starting from that perspective, this work involves the preparation and investigation of heterobinuclear catalysts for the electrochemical oxidation of methanol.

  16. Ruthenium–Platinum Catalysts and Direct Methanol Fuel Cells (DMFC: A Review of Theoretical and Experimental Breakthroughs

    Directory of Open Access Journals (Sweden)

    Ana S. Moura

    2017-02-01

    Full Text Available The increasing miniaturization of devices creates the need for adequate power sources and direct methanol fuel cells (DMFC are a strong option in the various possibilities under current development. DMFC catalysts are mostly based on platinum, for its outperformance in three key areas (activity, selectivity and stability within methanol oxidation framework. However, platinum poisoning with products of methanol oxidation led to the use of alloys. Ruthenium–platinum alloys are preferred catalysts active phases for methanol oxidation from an industrial point of view and, indeed, ruthenium itself is a viable catalyst for this reaction. In addition, the route of methanol decomposition is crucial in the goal of producing H2 from water reaction with methanol. However, the reaction pathway remains elusive and new approaches, namely in computational methods, have been ensued to determine it. This article reviews the various recent theoretical approaches for determining the pathway of methanol decomposition, and systematizes their validation with experimental data, within methodological context.

  17. Stereospecific olefin polymerization catalysts

    Science.gov (United States)

    Bercaw, John E.; Herzog, Timothy A.

    1998-01-01

    A metallocene catalyst system for the polymerization of .alpha.-olefins to yield stereospecific polymers including syndiotactic, and isotactic polymers. The catalyst system includes a metal and a ligand of the formula ##STR1## wherein: R.sup.1, R.sup.2, and R.sup.3 are independently selected from the group consisting of hydrogen, C.sub.1 to C.sub.10 alkyl, 5 to 7 membered cycloalkyl, which in turn may have from 1 to 3 C.sub.1 to C.sub.10 alkyls as a substituent, C.sub.6 to C.sub.15 aryl or arylalkyl in which two adjacent radicals may together stand for cyclic groups having 4 to 15 carbon atoms which in turn may be substituted, or Si(R.sup.8).sub.3 where R.sup.8 is selected from the group consisting of C.sub.1 to C.sub.10 alkyl, C.sub.6 to C.sub.15 aryl or C.sub.3 to C.sub.10 cycloalkyl; R.sup.4 and R.sup.6 are substituents both having van der Waals radii larger than the van der Waals radii of groups R.sup.1 and R.sup.3 ; R.sup.5 is a substituent having a van der Waals radius less than about the van der Waals radius of a methyl group; E.sup.1, E.sup.2 are independently selected from the group consisting of Si(R.sup.9).sub.2, Si(R.sup.9).sub.2 --Si(R.sup.9).sub.2, Ge(R.sup.9).sub.2, Sn(R.sup.9).sub.2, C(R.sup.9).sub.2, C(R.sup.9).sub.2 --C(R.sup.9).sub.2, where R.sup.9 is C.sub.1 to C.sub.10 alkyl, C.sub.6 to C.sub.15 aryl or C.sub.3 to C.sub.10 cycloalkyl; and the ligand may have C.sub.S or C.sub.1 -symmetry. Preferred metals are selected from the group consisting of group III, group IV, group V or lanthanide group elements. The catalysts are used to prepare stereoregular polymers including polypropylene from .alpha.-olefin monomers.

  18. What Is the Optimum Strain for Pt Alloys for Oxygen Electroreduction?

    DEFF Research Database (Denmark)

    Escribano, Maria Escudero; Malacrida, Paolo; Velazquez-Palenzuela, Amado Andres

    2015-01-01

    In order to make low-temperature fuel cells commercially viable, it is crucial to develop oxygen reduction catalysts based on more active, stable and abundant materials. A fruitful strategy for enhancing the oxygen reduction reaction (ORR) activity is to alloy Pt with transition metals [1]. However......, commercial alloys of Pt and late transition metals such as Ni, Co or Fe are typically unstable under fuel-cell conditions [2]. The very negative enthalpy of formation of alloys of Pt and lanthanides could provide them with greater long term stability than Pt and late transition metals. Herein, we show...

  19. High strength alloys

    Energy Technology Data Exchange (ETDEWEB)

    Maziasz, Phillip James [Oak Ridge, TN; Shingledecker, John Paul [Knoxville, TN; Santella, Michael Leonard [Knoxville, TN; Schneibel, Joachim Hugo [Knoxville, TN; Sikka, Vinod Kumar [Oak Ridge, TN; Vinegar, Harold J [Bellaire, TX; John, Randy Carl [Houston, TX; Kim, Dong Sub [Sugar Land, TX

    2010-08-31

    High strength metal alloys are described herein. At least one composition of a metal alloy includes chromium, nickel, copper, manganese, silicon, niobium, tungsten and iron. System, methods, and heaters that include the high strength metal alloys are described herein. At least one heater system may include a canister at least partially made from material containing at least one of the metal alloys. At least one system for heating a subterranean formation may include a tubular that is at least partially made from a material containing at least one of the metal alloys.

  20. High strength alloys

    Science.gov (United States)

    Maziasz, Phillip James; Shingledecker, John Paul; Santella, Michael Leonard; Schneibel, Joachim Hugo; Sikka, Vinod Kumar; Vinegar, Harold J.; John, Randy Carl; Kim, Dong Sub

    2012-06-05

    High strength metal alloys are described herein. At least one composition of a metal alloy includes chromium, nickel, copper, manganese, silicon, niobium, tungsten and iron. System, methods, and heaters that include the high strength metal alloys are described herein. At least one heater system may include a canister at least partially made from material containing at least one of the metal alloys. At least one system for heating a subterranean formation may include a tublar that is at least partially made from a material containing at least one of the metal alloys.

  1. Characterization of rapidly and naturally quenched skeletal iron catalysts for FT synthesis

    Institute of Scientific and Technical Information of China (English)

    YAN Shi-run; QIAO Ming-hua; ZHU Yuan-long; FAN Kang-nian

    2004-01-01

    The slurry phase is a promising system for Fischer-Tropsch (FT) synthesis. Since the liquid medium efficiently removes the heat of reaction so that the steady-state reaction is easily achieved. High catalytic activity is maintained due to removal of waxy products from the catalyst surface by the action of solvent. In addition, CO-rich syngas from coal gasification can be directly used in FT synthesis which may increase the thermal efficiency of the indirect coal liquefaction. One of the important problems to be solved for slurry phase FT is the catalyst attrition and separation from wax residue. Fused iron and Raney iron were found to have high attrition resistance and easy to separate from wax in slurry phase FT synthesis, but their activity is relatively low. Amorphous alloys made by rapid quenching techniques have drawn increasing interest due to their superior mechanical,chemical and magnetic properties compared to the thermodynamically stable crystalline alloys of the same compositions. It is reported that rapidly quenched skeletal Ni catalyst showed higher catalytic activity than Raney Ni in selective hydrogenation of unsaturated organic functional groups.In this paper, Fe50Al50 (by weight) alloys with different quenching rates, rapid quenching (RQ) and natural quenching (NQ) were prepared for FT synthesis. The phase composition of alloys was characterized by XRD. The physical properties, thermal-stability and adsorption properties of skeletal Fe that was prepared by leaching aluminum of the corresponding alloy with aqueous solution of NaOH were also studied by BET, in situ XRD and H2- and CO-TPD. It is found from XRD patterns of the alloys that RQ Fe50Al50 is composed of orthorhombic phase, and NQ Fe50Al50 alloy is mainly composed of monoclinic phase. Meanwhile, diffraction peaks of the RQ alloy are seriously broadened. After leaching aluminum by aqueous solution of NaOH at the same conditions,skeletal Fe from the RQ alloy give the higher specific surface

  2. Creep Resistant Zinc Alloy

    Energy Technology Data Exchange (ETDEWEB)

    Frank E. Goodwin

    2002-12-31

    This report covers the development of Hot Chamber Die Castable Zinc Alloys with High Creep Strengths. This project commenced in 2000, with the primary objective of developing a hot chamber zinc die-casting alloy, capable of satisfactory service at 140 C. The core objectives of the development program were to: (1) fill in missing alloy data areas and develop a more complete empirical model of the influence of alloy composition on creep strength and other selected properties, and (2) based on the results from this model, examine promising alloy composition areas, for further development and for meeting the property combination targets, with the view to designing an optimized alloy composition. The target properties identified by ILZRO for an improved creep resistant zinc die-casting alloy were identified as follows: (1) temperature capability of 1470 C; (2) creep stress of 31 MPa (4500 psi); (3) exposure time of 1000 hours; and (4) maximum creep elongation under these conditions of 1%. The project was broadly divided into three tasks: (1) Task 1--General and Modeling, covering Experimental design of a first batch of alloys, alloy preparation and characterization. (2) Task 2--Refinement and Optimization, covering Experimental design of a second batch of alloys. (3) Task 3--Creep Testing and Technology transfer, covering the finalization of testing and the transfer of technology to the Zinc industry should have at least one improved alloy result from this work.

  3. Biocompatibility of dental alloys

    Energy Technology Data Exchange (ETDEWEB)

    Braemer, W. [Heraeus Kulzer GmbH and Co. KG, Hanau (Germany)

    2001-10-01

    Modern dental alloys have been used for 50 years to produce prosthetic dental restorations. Generally, the crowns and frames of a prosthesis are prepared in dental alloys, and then veneered by feldspar ceramics or composites. In use, the alloys are exposed to the corrosive influence of saliva and bacteria. Metallic dental materials can be classified as precious and non-precious alloys. Precious alloys consist of gold, platinum, and small amounts of non-precious components such as copper, tin, or zinc. The non-precious alloys are based on either nickel or cobalt, alloyed with chrome, molybdenum, manganese, etc. Titanium is used as Grade 2 quality for dental purposes. As well as the dental casting alloys, high purity electroplated gold (99.8 wt.-%) is used in dental technology. This review discusses the corrosion behavior of metallic dental materials with saliva in ''in vitro'' tests and the influence of alloy components on bacteria (Lactobacillus casei and Streptococcus mutans). The test results show that alloys with high gold content, cobalt-based alloys, titanium, and electroplated gold are suitable for use as dental materials. (orig.)

  4. Ceramic catalyst materials

    Energy Technology Data Exchange (ETDEWEB)

    Sault, A.G.; Gardner, T.J. [Sandia National Laboratories, Albuquerque, NM (United States); Hanprasopwattanna, A.; Reardon, J.; Datye, A.K. [Univ. of New Mexico, Albuquerque, NM (United States)

    1995-08-01

    Hydrous titanium oxide (HTO) ion-exchange materials show great potential as ceramic catalyst supports due to an inherently high ion-exchange capacity which allows facile loading of catalytically active transition metal ions, and an ability to be cast as thin films on virtually any substrate. By coating titania and HTO materials onto inexpensive, high surface area substrates such as silica and alumina, the economics of using these materials is greatly improved, particularly for the HTO materials, which are substantially more expensive in the bulk form than other oxide supports. In addition, the development of thin film forms of these materials allows the catalytic and mechanical properties of the final catalyst formulation to be separately engineered. In order to fully realize the potential of thin film forms of titania and HTO, improved methods for the deposition and characterization of titania and HTO films on high surface area substrates are being developed. By varying deposition procedures, titania film thickness and substrate coverage can be varied from the submonolayer range to multilayer thicknesses on both silica and alumina. HTO films can also be formed, but the quality and reproducibility of these films is not nearly as good as for pure titania films. The films are characterized using a combination of isopropanol dehydration rate measurements, point of zero charge (PZC) measurements, BET surface area, transmission electron microscopy (TEM), and elemental analysis. In order to assess the effects of changes in film morphology on catalytic activity, the films are being loaded with MoO{sub 3} using either incipient wetness impregnation or ion-exchange of heptamolybdate anions followed by calcining. The MoO{sub 3} is then sulfided to form MOS{sub 2}, and tested for catalytic activity using pyrene hydrogenation and dibenzothiophene (DBT) desulfurization, model reactions that simulate reactions occurring during coal liquefaction.

  5. Complex metallic alloys as new materials for additive manufacturing.

    Science.gov (United States)

    Kenzari, Samuel; Bonina, David; Marie Dubois, Jean; Fournée, Vincent

    2014-04-01

    Additive manufacturing processes allow freeform fabrication of the physical representation of a three-dimensional computer-aided design (CAD) data model. This area has been expanding rapidly over the last 20 years. It includes several techniques such as selective laser sintering and stereolithography. The range of materials used today is quite restricted while there is a real demand for manufacturing lighter functional parts or parts with improved functional properties. In this article, we summarize recent work performed in this field, introducing new composite materials containing complex metallic alloys. These are mainly Al-based quasicrystalline alloys whose properties differ from those of conventional alloys. The use of these materials allows us to produce light-weight parts consisting of either metal-matrix composites or of polymer-matrix composites with improved properties. Functional parts using these alloys are now commercialized.

  6. Electrodeposition of Compositionally Modulated Zinc-cobalt Alloy Multilayer Coatings

    Institute of Scientific and Technical Information of China (English)

    费敬银; 梁国正; 辛文利

    2005-01-01

    The effects of pulse parameters on the cobalt content, surface morphologies and grain size of Zn-Co alloy deposits were studied using a pulse plating technique with a square-wave current containing reverse pulse. Average current density and reverse anodic current density amongst the variables investigated have very strong effects on the cobalt content in the Zn-Co alloy deposits. Grain size, surface appearance and internal stress in the deposit were improved significantly by introducing the reverse current. Varieties of Zn-Co alloy compositionally modulated multilayer (CMM) coatings with large differences in cobalt contents for different sublayers were electrodeposited by designing corresponding waveforms using a computer-aided pulse plater and characterized in terms of surface morphologies. Cross-sectional morphologies of the Zn-Co alloy CMM coatings, examined using field emission gun scanning electron microscopy (FEGSEM), confirmed the layered structure.

  7. HIV/AIDS and Alcohol

    Science.gov (United States)

    ... Psychiatric Disorders Other Substance Abuse HIV/AIDS HIV/AIDS Human immunodeficiency virus (HIV) targets the body’s immune ... and often leads to acquired immune deficiency syndrome (AIDS). Each year in the United States, between 55, ...

  8. HIV, AIDS, and the Future

    Science.gov (United States)

    Skip Navigation Bar Home Current Issue Past Issues HIV / AIDS HIV, AIDS, and the Future Past Issues / Summer 2009 ... turn Javascript on. Photo: The NAMES Project Foundation HIV and AIDS are a global catastrophe. While advances ...

  9. The Science and Engineering of Durable Ultralow PGM Catalysts- 2012 DOE-EERE-FCT annual progress report

    Energy Technology Data Exchange (ETDEWEB)

    Garzon, Fernando H. [Los Alamos National Laboratory

    2012-07-16

    Minimizing the quantity of Pt group metals used in polymer membrane fuel cells (PEMFCs) is one of the remaining grand challenges for fuel cell commercialization. Tremendous progress has been achieved over the last two decades in decreasing the Pt loading required for efficient fuel cell performance. Unfortunately, the fluctuations in the price of Pt represent a substantial barrier to the economics of widespread fuel cell use. Durability and impurity tolerance are also challenges that are tightly coupled to fuel cell Pt electrode loading. Traditional approaches to decreasing the amount of Pt required for good performance include: (1) Increasing mass activity by decreasing Pt particle size by supporting on carbon; (2) Alloy formulation Pt-Co, Pt-Cr alloys to improve mass activity; (3) Increasing Pt utilization by optimization of electronic and ionic contact of the Pt particles; (4) Improving conductivity of the electronic and ionic conducting constituents of the membrane electrode assembly; and (5) Improving reactant to and product mass transport away from the electroactive sites. Recent novel approaches include the nanoengineering of core shell catalysts and Pt particles of unusual geometries such as nanowires/whiskers. The success of the aforementioned approaches has been great; however further advances using such approaches have been hampered by a lack of underlining scientific understanding of the catalyst activity, particle growth mechanisms, and optimization strategies for designing composite electrodes The objectives of this report are: (1) Development of durable, high mass activity Platinum Group Metal (PGM) cathode catalysts-enabling lower cost fuel cells; (2) Elucidation of the fundamental relationships between PGM catalyst shape, particle size and activity to help design better catalysts; (3) Optimization of the cathode electrode layer to maximize the performance of PGM catalysts-improving fuel cell performance and lowering cost; (4) Understanding the

  10. Development of GREET Catalyst Module

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Zhichao [Argonne National Lab. (ANL), Argonne, IL (United States). Energy Systems Division; Dunn, Jennifer B. [Argonne National Lab. (ANL), Argonne, IL (United States). Energy Systems Division; Cronauer, Donald C. [Argonne National Lab. (ANL), Argonne, IL (United States). Energy Systems Division

    2014-09-01

    Catalysts are critical inputs for many pathways that convert biomass into biofuels. Energy consumption and greenhouse gas (GHG) emissions during the production of catalysts and chemical inputs influence the life-cycle energy consumption, and GHG emissions of biofuels and need to be considered in biofuel life-cycle analysis (LCA). In this report, we develop energy and material flows for the production of three different catalysts (tar reforming, alcohol synthesis, Zeolite Socony Mobil-5 [ZSM-5]) and two chemicals (olivine, dimethyl ether of polyethylene glycol [DEPG]). These compounds and catalysts are now included in the Greenhouse Gases, Regulated Emissions and Energy Use in Transportation (GREET™) catalyst module. They were selected because they are consumed in existing U.S. Department of Energy (DOE) analyses of biofuel processes. For example, a thermochemical ethanol production pathway (indirect gasification and mixed alcohol synthesis) developed by the National Renewable Energy Laboratory (NREL) uses olivine, DEPG, and tar reforming and alcohol synthesis catalysts (Dutta et al., 2011). ZSM-5 can be used in biofuel production pathways such as catalytic upgrading of sugars into hydrocarbons (Biddy and Jones, 2013). Other uses for these compounds and catalysts are certainly possible. In this report, we document the data sources and methodology we used to develop material and energy flows for the catalysts and compounds in the GREET catalyst module. In Section 2 we focus on compounds used in the model Dutta et al. (2011) developed. In Section 3, we report material and energy flows associated with ZSM-5 production. Finally, in Section 4, we report results.

  11. Political dimensions of AIDS.

    Science.gov (United States)

    Blewett, N

    1988-01-01

    World political aspects and the example of Australia as a national political response to AIDS are presented. Global policy on AIDS is influenced by the fact that the AIDS epidemic is the 1st to be largely predictable, that long lag times occur between intervention and measurable events, and by the prompt, professional leadership of WHO, lead by Dr. J. Mann. WHO began a Global Programme on AIDS in 1987, modelled on the responses of Canada and Australia. A world summit of Ministers of Health was convened in January 1988. These moves generated a response qualified by openness, cooperation, hope and common sense. The AIDS epidemic calls for unprecedented involvement of politicians: they must coordinate medical knowledge with community action, deal with public fear, exert strong, rational leadership and avoid quick, appealing counterproductive responses. 3 clear directions must be taken to deal with the epidemic: 1) strong research and education campaigns; 2) close contact with political colleagues, interest groups and the community; 3) a national strategy which enjoins diverse interest groups, with courage, rationality and compassion. In Australia, the AIDS response began with the unwitting infection of 3 infants by blood transfusion. A public information campaign emphasizing a penetrating TV ad campaign was instituted in 1987. Policy discussions were held in all parliamentary bodies. The AIDS epidemic demands rapid, creative responses, a break from traditions in health bureaucracy, continual scrutiny of funding procedures and administrative arrangements. In practical terms in Australia, this meant establishing a special AIDS branch within the Health Advancement Division of the Community Health Department. AIDS issues must remain depoliticized to defuse adversary politics and keep leaders in a united front.

  12. Synthesis of PtRu nanoparticles from the hydrosilylation reaction and application as catalyst for direct methanol fuel cell.

    Science.gov (United States)

    Huang, Junchao; Liu, Zhaolin; He, Chaobin; Gan, Leong Ming

    2005-09-08

    Nanosized Pt, PtRu, and Ru particles were prepared by a novel process, the hydrosilylation reaction. The hydrosilylation reaction is an effective method of preparation not only for Pt particles but also for other metal colloids, such as Ru. Vulcan XC-72 was selected as catalyst support for Pt, PtRu, and Ru colloids, and TEM investigations showed nanoscale particles and narrow size distribution for both supported and unsupported metals. All Pt and Pt-rich catalysts showed the X-ray diffraction pattern of a face-centered cubic (fcc) crystal structure, whereas the Ru and Ru-rich alloys were more typical of a hexagonal close-packed (hcp) structure. As evidenced by XPS, most Pt and Ru atoms in the nanoparticles were zerovalent, except a trace of oxidation-state metals. The electrooxidation of liquid methanol on these catalysts was investigated at room temperature by cyclic voltammetry and chronoamperometry. The results concluded that some alloy catalysts showed higher catalytic activities and better CO tolerance than the Pt-only catalyst; Pt56Ru44/C have displayed the best electrocatalytic performance among all carbon-supported catalysts.

  13. Nanophase Nickel-Zirconium Alloys for Fuel Cells

    Science.gov (United States)

    Narayanan, Sekharipuram; Whitacre, jay; Valdez, Thomas

    2008-01-01

    Nanophase nickel-zirconium alloys have been investigated for use as electrically conductive coatings and catalyst supports in fuel cells. Heretofore, noble metals have been used because they resist corrosion in the harsh, acidic fuel cell interior environments. However, the high cost of noble metals has prompted a search for less-costly substitutes. Nickel-zirconium alloys belong to a class of base metal alloys formed from transition elements of widely different d-electron configurations. These alloys generally exhibit unique physical, chemical, and metallurgical properties that can include corrosion resistance. Inasmuch as corrosion is accelerated by free-energy differences between bulk material and grain boundaries, it was conjectured that amorphous (glassy) and nanophase forms of these alloys could offer the desired corrosion resistance. For experiments to test the conjecture, thin alloy films containing various proportions of nickel and zirconium were deposited by magnetron and radiofrequency co-sputtering of nickel and zirconium. The results of x-ray diffraction studies of the deposited films suggested that the films had a nanophase and nearly amorphous character.

  14. Aid and Growth

    DEFF Research Database (Denmark)

    Tarp, Finn; Mekasha, Tseday Jemaneh

    2013-01-01

    Recent litterature in the meta-analysis category where results from a range of studies are brought together throws doubt on the ability of foreign aid to foster economic growth and development. This article assesses what meta-analysis has to contribute to the litterature on the effectiveness...... of foreign aid in terms of growth impact. We re-examine key hypotheses, and find that the effect of aid on growth is positive and statistically significant. This significant effect is genuine, and not an artefact of publication selection. We also show why our results differ from those published elsewhere....

  15. Aid Supplies Over Time

    DEFF Research Database (Denmark)

    Jones, Edward Samuel

    2015-01-01

    What determines how much foreign aid donors provide? Existing answers to this question point to a complex range of influences. However, the tasks of distinguishing between long- and short-run factors, as well as differences between donors, have not been adequately addressed. Taking advantage...... of data spanning nearly 50 years, this paper uses panel cointegration techniques to consider these issues. The analysis provides clear evidence for heterogeneity both between donors and over time, bandwagon effects, and a growing influence of security considerations in aid provision. Domestic...... macroeconomic shocks have a moderate but delayed effect on aid disbursements....

  16. Aid and Growth

    DEFF Research Database (Denmark)

    Mekasha, Tseday Jemaneh; Tarp, Finn

    Some recent literature in the meta-analysis category where results from a range of studies are brought together throws doubt on the ability of foreign aid to foster economic growth and development. This paper assesses what meta-analysis has to say about the effectiveness of foreign aid in terms...... of the growth impact. We re-examine key hypotheses, and find that the effect of aid on growth is positive and statistically significant. This significant effect is genuine, and not an artefact of publication selection. We also show why our results differ from those published elsewhere....

  17. Platinum- and platinum alloy-coated palladium and palladium alloy particles and uses thereof

    Science.gov (United States)

    Adzic, Radoslav; Zhang, Junliang; Mo, Yibo; Vukmirovic, Miomir Branko

    2010-04-06

    The present invention relates to particle and nanoparticle composites useful as oxygen-reduction electrocatalysts. The particle composites are composed of a palladium or palladium-alloy particle or nanoparticle substrate coated with an atomic submonolayer, monolayer, bilayer, or trilayer of zerovalent platinum atoms. The invention also relates to a catalyst and a fuel cell containing the particle or nanoparticle composites of the invention. The invention additionally includes methods for oxygen reduction and production of electrical energy by using the particle and nanoparticle composites of the invention.

  18. Pulmonary complications of AIDS: radiologic features. [AIDS

    Energy Technology Data Exchange (ETDEWEB)

    Cohen, B.A.; Pomeranz, S.; Rabinowitz, J.G.; Rosen, M.J.; Train, J.S.; Norton, K.I.; Mendelson, D.S.

    1984-07-01

    Fifty-two patients with pulmonary complications of acquired immunodeficiency syndrome (AIDS) were studied over a 3-year period. The vast majority of the patients were homosexual; however, a significant number were intravenous drug abusers. Thirteen different organisms were noted, of which Pneumocystis carinii was by far the most common. Five patients had neoplasia. Most patients had initial abnormal chest films; however, eight patients subsequently shown to have Pneumocystis carinii pneumonia had normal chest films. A significant overlap in chest radiographic findings was noted among patients with different or multiple organisms. Lung biopsy should be an early consideration for all patients with a clinical history consistent with the pulmonary complications of AIDS. Of the 52 patients, 41 had died by the time this report was completed.

  19. Pt-Ni and Pt-M-Ni (M = Ru, Sn Anode Catalysts for Low-Temperature Acidic Direct Alcohol Fuel Cells: A Review

    Directory of Open Access Journals (Sweden)

    Ermete Antolini

    2017-01-01

    Full Text Available In view of a possible use as anode materials in acidic direct alcohol fuel cells, the electro-catalytic activity of Pt-Ni and Pt-M-Ni (M = Ru, Sn catalysts for methanol and ethanol oxidation has been widely investigated. An overview of literature data regarding the effect of the addition of Ni to Pt and Pt-M on the methanol and ethanol oxidation activity in acid environment of the resulting binary and ternary Ni-containing Pt-based catalysts is presented, highlighting the effect of alloyed and non-alloyed nickel on the catalytic activity of these materials.

  20. Impeded solid state reactions and transformations in ceramic catalysts supports and catalysts

    Directory of Open Access Journals (Sweden)

    Ernő E. Kiss

    2012-12-01

    Full Text Available Impeded chemical reactions and impeded polymorphous transformation in materials are discussed, as desired effects, for stabilization of ceramic catalyst supports and ceramic based catalysts. This paper gives a short overview about the possibilities of slowing down the aging processes in ceramic catalyst supports and catalysts. Special attention is given to alumina and titania based catalysts.

  1. An in-depth understanding of the bimetallic effects and coked carbon species on an active bimetallic Ni(Co)/Al2O3 dry reforming catalyst.

    Science.gov (United States)

    Liao, Xin; Gerdts, Rihards; Parker, Stewart F; Chi, Lina; Zhao, Yongxiang; Hill, Martyn; Guo, Junqiu; Jones, Martin O; Jiang, Zheng

    2016-06-29

    Ni/Al2O3, Co/Al2O3 and bimetallic Ni(Co)/Al2O3 catalysts were prepared using an impregnation method and employed in CO2 dry reforming of methane under coking-favored conditions. The spent catalysts were carefully characterized using typical characterization technologies and inelastic neutron scattering spectroscopy. The bimetallic catalyst exhibited a superior activity and anti-coking performance compared to Ni/Al2O3, while the most resistant to coking behavior was Co/Al2O3. The enhanced activity of the Ni(Co)/Al2O3 bimetallic catalyst is attributed to the reduced particle size of metallic species and resistance to forming stable filamentous carbon. The overall carbon deposition on the spent bimetallic catalyst is comparable to that of the spent Ni/Al2O3 catalyst, whereas the carbon deposited on the bimetallic catalyst is mainly less-stable carbonaceous species as confirmed by SEM, TPO, Raman and INS characterization. This study provides an in depth understanding of alloy effects in catalysts, the chemical nature of coked carbon on spent Ni-based catalysts and, hopefully, inspires the creative design of a new bimetallic catalyst for dry reforming reactions.

  2. Nano-Engineered Catalysts for Direct Methanol Fuel Cells

    Science.gov (United States)

    Myung, Nosang; Narayanan, Sekharipuram; Wiberg, Dean

    2008-01-01

    Nano-engineered catalysts, and a method of fabricating them, have been developed in a continuing effort to improve the performances of direct methanol fuel cells as candidate power sources to supplant primary and secondary batteries in a variety of portable electronic products. In order to realize the potential for high energy densities (as much as 1.5 W h/g) of direct methanol fuel cells, it will be necessary to optimize the chemical compositions and geometric configurations of catalyst layers and electrode structures. High performance can be achieved when catalyst particles and electrode structures have the necessary small feature sizes (typically of the order of nanometers), large surface areas, optimal metal compositions, high porosity, and hydrophobicity. The present method involves electrodeposition of one or more catalytic metal(s) or a catalytic-metal/polytetrafluoroethylene nanocomposite on an alumina nanotemplate. The alumina nanotemplate is then dissolved, leaving the desired metal or metal/polytetrafluoroethylene-composite catalyst layer. Unlike some prior methods of making fine metal catalysts, this method does not involve processing at elevated temperature; all processing can be done at room temperature. In addition, this method involves fewer steps and is more amenable to scaling up for mass production. Alumina nanotemplates are porous alumina membranes that have been fabricated, variously, by anodizing either pure aluminum or aluminum that has been deposited on silicon by electronbeam evaporation. The diameters of the pores (7 to 300 nm), areal densities of pores (as much as 7 x 10(exp 10)sq cm), and lengths of pores (up to about 100 nm) can be tailored by selection of fabrication conditions. In a given case, the catalytic metal, catalytic metal alloy, or catalytic metal/ polytetrafluoroethylene composite is electrodeposited in the pores of the alumina nanotemplate. The dimensions of the pores, together with the electrodeposition conditions

  3. Explorative catalyst screening studies on reforming of glycerol in supercritical water

    NARCIS (Netherlands)

    van Bennekom, J. G.; Kirillov, V. A.; Amosov, Y. I.; Krieger, T.; Venderbosch, R. H.; Assink, D.; Lemmens, K. P. J.; Heeres, H. J.

    2012-01-01

    An explorative screening study with Pt/CeZrO2, Ni/ZrO2. Ni/CaO-6Al(2)O(3), NiCu/CeZrO2, and a CuZn alloy was carried out to investigate the influence of different catalysts on the carbon-to-gas efficiency and gas composition in the reforming of glycerol in supercritical water. Experiments were condu

  4. On the Role of Surface Modifications of Palladium Catalysts in the Selective Hydrogenation of Acetylene

    DEFF Research Database (Denmark)

    Studt, Felix; Abild-Pedersen, Frank; Bligaard, Thomas;

    2008-01-01

    Summing Me up: DFT calculations have shown that alloying, subsurface carbon, and hydride formation, all increase the selectivity of Pd catalysts for acetylene hydrogenation by weakening the surface–adsorbate bond. A simple descriptor—the adsorption energy of a methyl group—has been used to quantify...... and compare the different effects in the adsorption of acetylene and ethylene on various transition-metal surfaces (see picture)....

  5. HIV/AIDS

    Science.gov (United States)

    ... equity (covering the populations in need of services). Financing for sustainability (covering the costs of services). Innovation for acceleration (looking towards the future). WHO is a cosponsor of the Joint United Nations Programme on AIDS (UNAIDS). Within UNAIDS, WHO leads ...

  6. First Aid: Croup

    Science.gov (United States)

    ... Development Infections Diseases & Conditions Pregnancy & Baby Nutrition & Fitness Emotions & Behavior School & Family Life First Aid & Safety Doctors & ... with each breath has a pale or bluish color around the mouth drools or has difficulty swallowing ...

  7. Buying a Hearing Aid

    Science.gov (United States)

    ... Contact Us Calendar ENTCareers Marketplace ENT Careers Marketplace Log in b Log in Toggle navigation b Join Now Donate Now ... using your hearing aids in quiet surroundings, gradually building up to noisier environments. Then eventually work up ...

  8. HIV/AIDS

    Science.gov (United States)

    HIV stands for human immunodeficiency virus. It harms your immune system by destroying the white blood cells ... It is the final stage of infection with HIV. Not everyone with HIV develops AIDS. HIV most ...

  9. AidData

    Data.gov (United States)

    US Agency for International Development — AidData is a research and innovation lab making information on development finance more accessible and actionable. Tracking more than $6 trillion dollars from 90+...

  10. Convulsions - first aid - slideshow

    Science.gov (United States)

    ... this page: //medlineplus.gov/ency/presentations/100212.htm Convulsions - first aid - series—Procedure, part 1 To use ... slide 2 out of 2 Overview When a seizure occurs, the main goal is to protect the ...

  11. Characterization of Catalyst Materials for Production of Aerospace Fuels

    Science.gov (United States)

    Best, Lauren M.; De La Ree, Ana B.; Hepp, Aloysius F.

    2012-01-01

    Due to environmental, economic, and security issues, there is a greater need for cleaner alternative fuels. There will undoubtedly be a shift from crude oil to non-petroleum sources as a feedstock for aviation (and other transportation) fuels. Additionally, efforts are concentrated on reducing costs coupled with fuel production from non-conventional sources. One solution to this issue is Fischer-Tropsch gas-to-liquid technology. Fischer-Tropsch processing of synthesis gas (CO/H2) produces a complex product stream of paraffins, olefins, and oxygenated compounds such as alcohols and aldehydes. The Fisher-Tropsch process can produce a cleaner diesel oil fraction with a high cetane number (typically above 70) without any sulfur or aromatic compounds. This process is most commonly catalyzed by heterogeneous (in this case, silver and platinum) catalysts composed of cobalt supported on alumina or unsupported alloyed iron powders. Physisorption, chemisorptions, scanning electron microscopy (SEM), and energy dispersive spectroscopy (EDS) are described to better understand the potential performance of Fischer-Tropsch cobalt on alumina catalysts promoted with silver and platinum. The overall goal is to preferentially produce C8 to C18 paraffin compounds for use as aerospace fuels. Progress towards this goal will eventually be updated and achieved by a more thorough understanding of the characterization of catalyst materials. This work was supported by NASA s Subsonic Fixed Wing and In-situ Resource Utilization projects.

  12. Thermodynamics-Based Computational Design of Al-Mg-Sc-Zr Alloys

    Science.gov (United States)

    Haidemenopoulos, G. N.; Katsamas, A. I.; Kamoutsi, H.

    2010-04-01

    Alloying additions of Sc and Zr raise the yield strength of Al-Mg alloys significantly. We have studied the effects of Sc and Zr on the grain refinement and recrystallization resistance of Al-Mg alloys with the aid of computational alloy thermodynamics. The grain refinement potential has been assessed by Scheil-Gulliver simulations of solidification paths, while the recrystallization resistance (Zener drag) has been assessed by calculation of the precipitation driving forces of the Al3Sc and Al3Zr intermetallics. Microstructural performance indices have been derived, used to rank several alloy composition variants, and finally select the variant with the best combination of grain refinement and recrystallization resistance. The method can be used, with certain limitations, for a thermodynamics-based design of Al-Mg and other alloy compositions.

  13. Hypophyseal pathology in AIDS

    OpenAIRE

    Mosca, L; Costanzi, G; Antonacci, C.; Boldorini, R; Carboni, N.; Cristina, S; Liberani, C.; Parravicini, C.; Pirolo, A.; Vago, L

    1992-01-01

    One hundred and eleven pituitary glands of patients (93 males, 18 females; mean age 32 years, 5 months) who died of fully developed AIDS or ARC were examined under light microscopy with the aid of immunohistochemistry. On post mortem (p.m.) examination a wide series of multiorgan alterations was noticed. Microscopically vanous lesions in both adeno- and neurohypophysis were seen. These ranged from vessel damage to secondaries to systemic infections, neoplas...

  14. Plasma-aided manufacturing

    Science.gov (United States)

    Shohet, J. L.

    1993-12-01

    Plasma-aided manufacturing is used for producing new materials with unusual and superior properties, for developing new chemical compounds and processes, for machining, and for altering and refining materials and surfaces. Plasma-aided manufacturing has direct applications to semiconductor fabrication, materials synthesis, welding, lighting, polymers, anti-corrosion coatings, machine tools, metallurgy, electrical and electronics devices, hazardous waste removal, high performance ceramics, and many other items in both the high-technology and the more traditional industries in the United States.

  15. Triangular Ag-Pd alloy nanoprisms: rational synthesis with high-efficiency for electrocatalytic oxygen reduction

    Science.gov (United States)

    Xu, Lin; Luo, Zhimin; Fan, Zhanxi; Zhang, Xiao; Tan, Chaoliang; Li, Hai; Zhang, Hua; Xue, Can

    2014-09-01

    We report the generation of triangular Ag-Pd alloy nanoprisms through a rationally designed synthetic strategy based on silver nanoprisms as sacrificial templates. The galvanic replacement between Ag nanoprisms and H2PdCl4 along with co-reduction of Ag+/Pd2+ is responsible for the formation of final prismatic Ag-Pd alloy nanostructures. Significantly, these Ag-Pd alloy nanoprisms exhibited superior electrocatalytic activity for the oxygen reduction reaction (ORR) as compared with the commercial Pd/C catalyst. Such a high catalytic activity is attributed to not only the alloyed Ag-Pd composition but also the dominant {111} facets of the triangular Ag-Pd nanoprisms. This work demonstrates the rational design of bimetallic alloy nanostructures with control of selective crystal facets that are critical to achieve high catalytic activity for fuel cell systems.We report the generation of triangular Ag-Pd alloy nanoprisms through a rationally designed synthetic strategy based on silver nanoprisms as sacrificial templates. The galvanic replacement between Ag nanoprisms and H2PdCl4 along with co-reduction of Ag+/Pd2+ is responsible for the formation of final prismatic Ag-Pd alloy nanostructures. Significantly, these Ag-Pd alloy nanoprisms exhibited superior electrocatalytic activity for the oxygen reduction reaction (ORR) as compared with the commercial Pd/C catalyst. Such a high catalytic activity is attributed to not only the alloyed Ag-Pd composition but also the dominant {111} facets of the triangular Ag-Pd nanoprisms. This work demonstrates the rational design of bimetallic alloy nanostructures with control of selective crystal facets that are critical to achieve high catalytic activity for fuel cell systems. Electronic supplementary information (ESI) available. See DOI: 10.1039/c4nr03600j

  16. Preparation of PdCu Alloy Nanocatalysts for Nitrate Hydrogenation and Carbon Monoxide Oxidation

    Directory of Open Access Journals (Sweden)

    Fan Cai

    2016-06-01

    Full Text Available Alloying Pd with Cu is important for catalytic reactions such as denitrification reaction and CO oxidation reaction, but understanding of the catalyst preparation and its correlation with the catalyst’s activity and selectivity remains elusive. Herein, we report the results of investigations of the preparation of PdCu alloy nanocatalysts using different methods and the catalytic properties of the catalysts in catalytic denitrification reaction and CO oxidation reaction. PdCu alloy nanocatalysts were prepared by conventional dry impregnation method and ligand-capping based wet chemical synthesis method, and subsequent thermochemical activation as well. The alloying characteristics depend on the bimetallic composition. PdCu/Al2O3 with a Pd/Cu ratio of 50:50 was shown to exhibit an optimized hydrogenation activity for the catalytic denitrification reaction. The catalytic activity of the PdCu catalysts was shown to be highly dependent on the support, as evidenced by the observation of an enhanced catalytic activity for CO oxidation reaction using TiO2 and CeO2 supports with high oxygen storage capacity. Implications of the results to the refinement of the preparation of the alloy nanocatalysts are also discussed.

  17. THE AIDS HANDBOOK

    Directory of Open Access Journals (Sweden)

    Z Khan

    1997-12-01

    Full Text Available HIV infection and AIDS is increasingly becoming a major public health problem in our country. Currently, the reported cases represent only the 'tip of the iceberg' of the problem. In view of the fact that no cure or vaccine for the disease has yet been found, spreading knowledge and removing misconceptions is about the only way that AIDS can be effectively tackled.This handbook, developed by Prof. Shankar Chowdhury and associates, seeks to address all levels of medical and non-medical AIDS workers, as well as the layman. It deals with topics ranging from biology of the virus, symptoms and transmission of disease, to prevention, counselling for infected persons and action plan for AIDS education.The biology of the virus and the immune system is described in simple terms, as well as methods of testing for HIV, and what these test results mean. The progression of disease in adults and children, development of symptoms, diagnostic criteria for AIDS, treatment and outcome of disease is dealt with. How AIDS spreads between people, and the health risk for health workers and families is examined. The various ways in which transmission of HIV can be prevented is looked at in detail, including public health measures, national and internatonal action, and ethical and human rights issues involved.

  18. Hollow raspberry-like PdAg alloy nanospheres: High electrocatalytic activity for ethanol oxidation in alkaline media

    Science.gov (United States)

    Peng, Cheng; Hu, Yongli; Liu, Mingrui; Zheng, Yixiong

    2015-03-01

    Palladium-silver (PdAg) alloy nanospheres with unique structure were prepared using a one-pot procedure based on the galvanic replacement reaction. Their electrocatalytic activity for ethanol oxidation in alkaline media was evaluated. The morphology and crystal structure of the samples were characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM) and X-ray diffraction (XRD). Electrochemical characterization techniques, including cyclic voltammetry (CV) and chronoamperometry (CA) measurements were used to analyze the electrochemical performance of the PdAg alloy nanospheres. The SEM and TEM images showed that the PdAg alloy nanospheres exhibit a hierarchical nanostructure with hollow interiors and porous walls. Compared to the commercial Pd/C catalyst, the as-prepared PdAg alloy nanospheres exhibit superior electrocatalytic activity and stability towards ethanol electro-oxidation in alkaline media, showing its potential as a new non-Pt electro-catalyst for direct alcohol fuel cells (DAFCs).

  19. Alloying Au surface with Pd reduces the intrinsic activity in catalyzing CO oxidation

    KAUST Repository

    Qian, Kun

    2016-03-30

    © 2016. Various Au-Pd/SiO2 catalysts with a fixed Au loading but different Au:Pd molar ratios were prepared via deposition-precipitation method followed by H2 reduction. The structures were characterized and the catalytic activities in CO oxidation were evaluated. The formation of Au-Pd alloy particles was identified. The Au-Pd alloy particles exhibit enhanced dispersions on SiO2 than Au particles. Charge transfer from Pd to Au within Au-Pd alloy particles. Isolated Pd atoms dominate the surface of Au-Pd alloy particles with large Au:Pd molar ratios while contiguous Pd atoms dominate the surface of Au-Pd alloy particles with small Au:Pd molar ratios. Few synergetic effect of Au-Pd alloy occurs on catalyzing CO oxidation under employed reaction conditions. Alloying Au with Pd reduces the intrinsic activity in catalyzing CO oxidation, and contiguous Pd atoms on the Au-Pd alloy particles are capable of catalyzing CO oxidation while isolated Pd atoms are not. These results advance the fundamental understandings of Au-Pd alloy surfaces in catalyzing CO oxidation.

  20. Multilateral Aid | L’aide multilatérale

    Directory of Open Access Journals (Sweden)

    2012-05-01

    Full Text Available Bilateral and Multilateral Aid, DAC Members, 1960–2010 (in million USD constant, 2009Aide bilatérale et multilatérale des pays membres du CAD, 1960-2010 (en millions USD constants de 2009­Bilateral and Multilateral Aid by Recipient Region, DAC Members, 2008 (in percentage of total aid by RegionAide bilatérale et multilatérale des pays membres du CAD par region de destination, 2008 (en pourcentage de l’aide totale par régionSources: OECD (2010 2010 DAC Report on Multilateral Aid (Paris: O...

  1. Palladium-tin catalysts for the direct synthesis of H₂O₂ with high selectivity.

    Science.gov (United States)

    Freakley, Simon J; He, Qian; Harrhy, Jonathan H; Lu, Li; Crole, David A; Morgan, David J; Ntainjua, Edwin N; Edwards, Jennifer K; Carley, Albert F; Borisevich, Albina Y; Kiely, Christopher J; Hutchings, Graham J

    2016-02-26

    The direct synthesis of hydrogen peroxide (H2O2) from H2 and O2 represents a potentially atom-efficient alternative to the current industrial indirect process. We show that the addition of tin to palladium catalysts coupled with an appropriate heat treatment cycle switches off the sequential hydrogenation and decomposition reactions, enabling selectivities of >95% toward H2O2. This effect arises from a tin oxide surface layer that encapsulates small Pd-rich particles while leaving larger Pd-Sn alloy particles exposed. We show that this effect is a general feature for oxide-supported Pd catalysts containing an appropriate second metal oxide component, and we set out the design principles for producing high-selectivity Pd-based catalysts for direct H2O2 production that do not contain gold.

  2. Origin of low temperature deactivation of Ni5Ga3 nanoparticles as catalyst for methanol synthesis

    DEFF Research Database (Denmark)

    Gardini, Diego; Sharafutdinov, Irek; Damsgaard, Christian Danvad

    In an effort to find alternative energy sources capable to compete with fossil fuels, methanol synthesis could represent a realistic solution to store “green” hydrogen produced from electrolysis or photo-induced water splitting. Recently, density functional theory (DFT) calculations [1] proposed Ni......-Ga alloys as active catalysts for methanol production from syngas mixtures and Ni-Ga nanoparticles supported on highly porous silica have been prepared using an incipient wetness impregnation technique from a solution of nickel and gallium nitrates [2]. Tests conducted in a fixed-bed reactor showed...... as catalyst for methanol production. Synthesis, followed by deactivation and a series of regeneration steps at increasing temperature in pure H2 has been carried out in a fixed-bed reactor connected to a gas chromatography system. In each regeneration step, CH4 is generated and the activity of the catalyst...

  3. The innovation catalysts.

    Science.gov (United States)

    Martin, Roger L

    2011-06-01

    A few years ago the software development company Intuit realized that it needed a new approach to galvanizing customers. The company's Net Promoter Score was faltering, and customer recommendations of new products were especially disappointing. Intuit decided to hold a two-day, off-site meeting for the company's top 300 managers with a focus on the role of design in innovation. One of the days was dedicated to a program called Design for Delight. The centerpiece of the day was a PowerPoint presentation by Intuit founder Scott Cook, who realized midway through that he was no Steve Jobs: The managers listened dutifully, but there was little energy in the room. By contrast, a subsequent exercise in which the participants worked through a design challenge by creating prototypes, getting feedback, iterating, and refining, had them mesmerized. The eventual result was the creation of a team of nine design-thinking coaches--"innovation catalysts"--from across Intuit who were made available to help any work group create prototypes, run experiments, and learn from customers. The process includes a "painstorm" (to determine the customer's greatest pain point), a "soljam" (to generate and then winnow possible solutions), and a "code-jam" (to write code "good enough" to take to customers within two weeks). Design for Delight has enabled employees throughout Intuit to move from satisfying customers to delighting them.

  4. Carbon nanotubes and other nanostructures as support material for nanoparticulate noble-metal catalysts in fuel cells

    DEFF Research Database (Denmark)

    Veltzé, Sune; Larsen, Mikkel Juul; Elina, Yli-Rantala

    or platinum-alloy catalysts in the electrodes are required. To maximize the utilization of the noble metal it is frequently deposited as nanoparticles (1–5 nm) on a stabilizing support of carbon black. Carbon black provides good anchoring of the catalyst particles, but is prone to severe destructive oxidation...... of the fuel-cell electrodes. However, the low concentration of structural defects also poses challenges with regard to anchoring of the catalyst particles on the CNT surface. Thus, activation treatments introducing surface functional groups may be necessary. Also, the surface properties are responsible...... for difficulties in contacting the nanotubes with other substances in the electrode or electrode preparation. Other promising candidate structures for catalyst support include carbon nanofibers (CNF) and various modifications of CNTs. We present some of our work with the investigation of surface properties...

  5. Carbon Nanotubes and Other Nanostructures as Support Material for Nanoparticulate Noble-Metal Catalysts in Fuel Cells

    DEFF Research Database (Denmark)

    Larsen, Mikkel Juul; Veltzé, Sune; Skou, Eivind Morten

    or platinum-alloy catalysts in the electrodes are required. To maximize the utilization of the noble metal it is frequently deposited as nanoparticles (1-5 nm) on a stabilizing support of carbon black. Carbon black provides good anchoring of the catalyst particles, but is prone to severe destructive oxidation...... of the fuel-cell electrodes. However, the low concentration of structural defects also poses challenges with regard to anchoring of the catalyst particles on the CNT surface. Thus, activation treatments introducing surface functional groups may be necessary. Also, the surface properties are responsible...... for difficulties in contacting the nanotubes with other substances in the electrode or electrode preparation. Other promising candidate structures for catalyst support include carbon nanofibers (CNF) and various modifications of CNTs. We present some of our work with the investigation of surface properties...

  6. Low-temperature steam-reforming of ethanol over ZnO-supported Ni and Cu catalysts

    Energy Technology Data Exchange (ETDEWEB)

    Homs, Narcis; Llorca, Jordi; De la Piscina, Pilar Ramirez [Departament de Quimica Inorganica, Universitat de Barcelona, C/Marti i Franques 1-11, 08028 Barcelona (Spain)

    2006-08-15

    ZnO-supported Ni and Cu as well as bimetallic Co-Ni and Co-Cu catalysts containing ca. 0.7wt% sodium promoter and prepared by the co-precipitation method were tested in the ethanol steam-reforming reaction at low temperature (523-723K), using a bioethanol-like mixture diluted in Ar. Monometallic ZnO-supported Cu or Ni samples do not exhibit good catalytic performance in the steam-reforming of ethanol for hydrogen production. Copper catalyst mainly dehydrogenates ethanol to acetaldehyde, whereas nickel catalyst favours ethanol decomposition. However, the addition of Ni to ZnO-supported cobalt has a positive effect both on the production of hydrogen at low temperature (<573K), and on catalyst stability. Evidence for alloy formation as well as mixed oxides at the microstructural level was found in the bimetallic systems after running the ethanol steam-reforming reaction by HRTEM-EELS. (author)

  7. PLUTONIUM-ZIRCONIUM ALLOYS

    Science.gov (United States)

    Schonfeld, F.W.; Waber, J.T.

    1960-08-30

    A series of nuclear reactor fuel alloys consisting of from about 5 to about 50 at.% zirconium (or higher zirconium alloys such as Zircaloy), balance plutonium, and having the structural composition of a plutonium are described. Zirconium is a satisfactory diluent because it alloys readily with plutonium and has desirable nuclear properties. Additional advantages are corrosion resistance, excellent fabrication propenties, an isotropie structure, and initial softness.

  8. Visible Light Responsive Catalysts Using Quantum Dot-Modified Ti02 for Air and Water Purification

    Science.gov (United States)

    Coutts, Janelle L.; Levine, Lanfang H.; Richards, Jeffrey T.; Hintze, paul; Clausen, Christian

    2012-01-01

    The method of photocatalysis utilizing titanium dioxide, TiO2, as the catalyst has been widely studied for trace contaminant control for both air and water applications because of its low energy consumption and use of a regenerable catalyst. Titanium dioxide requires ultraviolet light for activation due to its band gap energy of 3.2 eV. Traditionally, Hg-vapor fluorescent light sources are used in PCO reactors and are a setback for the technology for space application due to the possibility of Hg contamination. The development of a visible light responsive (VLR) TiO2-based catalyst could lead to the use of solar energy in the visible region (approx.45% of the solar spectrum lies in the visible region; > 400 nm) or highly efficient LEDs (with wavelengths > 400 nm) to make PCO approaches more efficient, economical, and safe. Though VLR catalyst development has been an active area of research for the past two decades, there are few commercially available VLR catalysts; those that are available still have poor activity in the visible region compared to that in the UV region. Thus, this study was aimed at the further development of VLR catalysts by a new method - coupling of quantum dots (QD) of a narrow band gap semiconductor (e.g., CdS, CdSe, PbS, ZnSe, etc.) to the TiO2 by two preparation methods: 1) photodeposition and 2) mechanical alloying using a high-speed ball mill. A library of catalysts was developed and screened for gas and aqueous phase applications, using ethanol and 4-chlorophenol as the target contaminants, respectively. Both target compounds are well studied in photocatalytic systems serve as model contaminants for this research. Synthesized catalysts were compared in terms of preparation method, type of quantum dots, and dosage of quantum dots.

  9. Influence of pretreatment condition of metal support on performance of metal supported hexaaluminate catalyst for methane combustion%金属载体预处理条件对催化燃烧用整体式六铝酸盐催化剂性能的影响

    Institute of Scientific and Technical Information of China (English)

    翟彦青; 李鑫钢; 李永丹

    2005-01-01

    Catalytic combustion of methane is one of the most promising processes to generate environmentally clean energy. Hexaaluminate (HA) monolithic catalyst is regarded as one of the potential catalytic materials under high temperature condition. In this work, the influence of pretreatment method of metal support (FeCr alloy) on the performance of metal supported hexaaluminate catalyst for methane combustion was studied firstly.

  10. NICKEL-BASE ALLOY

    Science.gov (United States)

    Inouye, H.; Manly, W.D.; Roche, T.K.

    1960-01-19

    A nickel-base alloy was developed which is particularly useful for the containment of molten fluoride salts in reactors. The alloy is resistant to both salt corrosion and oxidation and may be used at temperatures as high as 1800 deg F. Basically, the alloy consists of 15 to 22 wt.% molybdenum, a small amount of carbon, and 6 to 8 wt.% chromium, the balance being nickel. Up to 4 wt.% of tungsten, tantalum, vanadium, or niobium may be added to strengthen the alloy.

  11. Computer aided materials design; Keisanki zairyo sekkei

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1997-03-01

    The questionnaire survey on the computer aided materials design (CAMD), and the survey of current domestic and overseas software concerned were carried out to clarify developmental issues. The current elementary technology of CAMD was also surveyed to study its several problems caused with a progress of material design technology due to drastic diffusion of CAMD. This project aims at establishment of a new demanded software, computer chemistry, focusing attention on functional materials such as catalyst, polymer and non-linear electronic materials. Microscopic simulation technology was mainly surveyed in fiscal 1996. Although some fruitful results have been obtained in the fields of medical and agricultural chemicals, organic compounds, proteins, catalysts and electronic materials, such some problems are pointed out as `CAMD cannot handle an actual size of the target system` and `commercially available software are very expensive.` Reliable tool development as elementary technology, and the verification of its applications are thus required. Meso-dynamics, polymers, surface reaction and integrated technological environment attract users` attention. 27 refs., 16 figs., 2 tabs.

  12. Fischer-Tropsch Catalyst for Aviation Fuel Production

    Science.gov (United States)

    DeLaRee, Ana B.; Best, Lauren M.; Bradford, Robyn L.; Gonzalez-Arroyo, Richard; Hepp, Aloysius F.

    2012-01-01

    As the oil supply declines, there is a greater need for cleaner alternative fuels. There will undoubtedly be a shift from crude oil to nonpetroleum sources as a feedstock for aviation (and other transportation) fuels. The Fischer-Tropsch process uses a gas mixture of carbon monoxide and hydrogen which is converted into various liquid hydrocarbons; this versatile gas-to-liquid technology produces a complex product stream of paraffins, olefins, and oxygenated compounds such as alcohols and aldehydes. The Fischer-Tropsch process can produce a cleaner diesel oil fraction with a high cetane number (typically above 70) without any sulfur and aromatic compounds. It is most commonly catalyzed by cobalt supported on alumina, silica, or titania or unsupported alloyed iron powders. Cobalt is typically used more often than iron, in that cobalt is a longer-active catalyst, has lower water-gas shift activity, and lower yield of modified products. Promoters are valuable in improving Fischer-Tropsch catalyst as they can increase cobalt oxide dispersion, enhance the reduction of cobalt oxide to the active metal phase, stabilize a high metal surface area, and improve mechanical properties. Our goal is to build up the specificity of the Fischer-Tropsch catalyst while adding less-costly transition metals as promoters; the more common promoters used in Fischer-Tropsch synthesis are rhenium, platinum, and ruthenium. In this report we will describe our preliminary efforts to design and produce catalyst materials to achieve our goal of preferentially producing C8 to C18 paraffin compounds in the NASA Glenn Research Center Gas-To-Liquid processing plant. Efforts at NASA Glenn Research Center for producing green fuels using non-petroleum feedstocks support both the Sub-sonic Fixed Wing program of Fundamental Aeronautics and the In Situ Resource Utilization program of the Exploration Technology Development and Demonstration program.

  13. Women and AIDS: introduction.

    Science.gov (United States)

    Krieger, N; Margo, G

    1991-01-01

    Around the world, more and more women--principally poor women of color--are being diagnosed with and are dying of AIDS, the acquired immune deficiency syndrome. Yet, effective and appropriate prevention programs for women are sorely missing from the global program to control AIDS. To help us understand why this gap exists, and what we must do to close it, the three articles in this issue focus on women and AIDS. Examining the situation in such countries as Zimbabwe and South Africa, as well as in other economically underdeveloped and developed regions, the authors argue that women with the least control over their bodies and their lives are at greatest risk of acquiring AIDS. For example, the high rate of infection among women in Africa cannot be understood apart from the legacy of colonialism (including land expropriation and the forced introduction of a migrant labor system) and the insidious combination of traditional and European patriarchal values. Only by recognizing the socioeconomic and cultural determinants of both disease and sexual behavior, and only by incorporating these insights into our AIDS prevention programs, will we be able to curb the spread of this lethal disease.

  14. AIDS in Africa.

    Science.gov (United States)

    Mokhobo, D

    1989-03-01

    Numerous cultural practices and attitudes in Africa represent formidable obstacles to the prevention of the further spread of acquired immunodeficiency syndrome (AIDS). Polygamy and concubinage are still widely practiced throughout Africa. In fact, sexual promiscuity on the part of males is traditionally viewed as positive--a reflection of male supremacy and male sexual prowess. The disintegration of the rural African family, brought about by urbanization, the migrant labor system, and poverty, has resulted in widespread premarital promiscuity. Contraceptive practices are perceived by many as a white conspiracy aimed at limiting the growth of the black population and thereby diminishing its political power. Condom use is particularly in disfavor. Thus, AIDS prevention campaigns urging Africans to restrict the number of sexual partners and to use condoms are unlikely to be successful. Another problem is that most Africans cannot believe that AIDS is sexually linked in that the disease does not affect the sex organs as is the case with other sexually transmitted diseases. The degree to which African governments are able to allocate resources to AIDS education will determine whether the epidemic can be controlled. Even with a massive outpouring of resources, it may be difficult to arouse public alarm about AIDS since Africans are so acclimated to living with calamities of every kind.

  15. Utilizing various test methods to study the stress corrosion behavior of Al-Li-Cu alloys

    Science.gov (United States)

    Pizzo, P. P.; Galvin, R. P.; Nelson, H. G.

    1984-01-01

    Recently, much attention has been given to aluminum-lithium alloys because of rather substantial specific-strength and specific-stiffness advantages offered over commercial 2000and 7000-series aluminum alloys. An obstacle to Al-Li alloy development has been inherent limited ductility. In order to obtain a more refined microstructure, powder metallurgy (P/M) has been employed in alloy development programs. As stress corrosion (SC) of high-strength aluminum alloys has been a major problem in the aircraft industry, the possibility of an employment of Al-Li alloys has been considered, taking into account a use of Al-Li-Cu alloys. Attention is given to a research program concerned with the evaluation of the relative SC resistance of two P/M processed Al-Li-Cu alloys. The behavior of the alloys, with and without an addition of magnesium, was studied with the aid of three test methods. The susceptibility to SC was found to depend on the microstructure of the alloys.

  16. Correlation of recalescence with grain refinement of magnesium alloys

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    The grain refinement of Mg-Al based alloys with carbon inoculation was investigated by a computer-aided cooling curve analysis(CA-CCA)system.The results show that carbon inoculation decreases the main parameters of the recalescence regime during the initial stage of solidification.These parameters include the recalescence undercooling(△θrec),duration of recalescence (trec),and liquid peak parameter(LPP)which is firstly introduced into magnesium alloys.The resultant grain size decreases with increasing nucleation temperature(θn)and decreasing values of △θrec,trec and LPE

  17. AIDS ORPHANS GET SPECIAL VISITOR

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    Chinese Premier Wen Jiabao visits AIDS orphans in Shangcai County,central China’s Henan Province,on November 30,a day before the 20th World AIDS Day. The region of Shangcai has the highest concentration of people living with HIV/AIDS in China. The Chinese Government has released a package of policies that offer people living with HIV/AIDS free medicine,health checks and consultations,as well as free schooling to AIDS orphans.

  18. Synthesis and Electrochemical Evaluation of Carbon Supported Pt-Co Bimetallic Catalysts Prepared by Electroless Deposition and Modified Charge Enhanced Dry Impregnation

    Directory of Open Access Journals (Sweden)

    John Meynard M. Tengco

    2016-06-01

    Full Text Available Carbon-supported bimetallic Pt-Co cathode catalysts have been previously identified as higher activity alternatives to conventional Pt/C catalysts for fuel cells. In this work, a series of Pt-Co/C catalysts were synthesized using electroless deposition (ED of Pt on a Co/C catalyst prepared by modified charge enhanced dry impregnation. X-ray diffraction (XRD and scanning transmission electron microscopy (STEM characterization of the base catalyst showed highly dispersed particles. A basic ED bath containing PtCl62− as the Pt precursor, dimethylamine borane as reducing agent, and ethylenediamine as stabilizing agent successfully targeted deposition of Pt on Co particles. Simultaneous action of galvanic displacement and ED resulted in Pt-Co alloy formation observed in XRD and energy dispersive X-ray spectroscopy (XEDS mapping. In addition, fast deposition kinetics resulted in hollow shell Pt-Co alloy particles while particles with Pt-rich shell and Co-rich cores formed with controlled Pt deposition. Electrochemical evaluation of the Pt-Co/C catalysts showed lower active surface but much higher mass and surface activities for oxygen reduction reaction compared to a commercial Pt/C fuel cell catalyst.

  19. Mechanical Properties and Friction/Wear Behavior of Copper Alloyed Powder Composites

    Institute of Scientific and Technical Information of China (English)

    DENG Chen-hong; CHEN Guang-zhi; GE Qi-lu

    2005-01-01

    Copper alloyed powder composites containing nanoparticles were developed by hot pressing. Effects of nanoscale activated sintering aid and fine ceramic particles Al2O3 on hardness, working quality, and behaviors of friction and wear of the composites have been studied, compared with the composites including microscale activated sintering aid and microscale ceramic particles. The microstructures of the samples were analyzed by SEM. The results show that the materials with nanoscale sintering aid and fine ceramic particles have better mechanical properties and abrasive resistance than the materials with microscale activated sintering aid and microceramic particles. Moreover, element mutual transfer occurs between samples (strip) and abrasive wheel (ring).

  20. AIDS in Colombia.

    Science.gov (United States)

    Boshell, J; Gacharná, M G; García, M; Jaramillo, L S; Márquez, G; Fergusson, M M; González, S; Prada, E Y; de Rangel, R; de Cabas, R

    1989-01-01

    Between January 1984 and December 1987 a total of 178 AIDS cases were reported to the Colombian Ministry of Health. The location of these cases suggests that the human immunodeficiency virus (HIV) is widely distributed in Colombia. Most of those afflicted (97%) have been adult males. HIV seroprevalence studies of selected population groups revealed the highest antibody prevalence (5.65% in females, 22.5% in males) among individuals involved in high-risk behaviors who participated in a free AIDS testing program. High prevalences (from 0.6% to 3.9% in females, and 14.6% to 15.9% in males) were also found in patients (primarily female prostitutes and male homosexuals) attending clinics for sexually transmitted diseases in several urban areas. The number of AIDS cases in Colombia has doubled or tripled annually since reporting began in 1984, a pattern similar to that observed worldwide.

  1. [AIDS mortality in France].

    Science.gov (United States)

    Hatton, F; Maguin, P; Nicaud, V; Renaud, G

    1986-01-01

    A study about mortality by AIDS had been undertaken since July 1st 1983, in the Service of Information on Medical causes of Death (INSERM SC8), which is in charge of developing mortality statistics in France. From July 1st 1983 to September 30th 1985, 243 deaths due to AIDS were recorded. Only the cases where this diagnosis was clearly mentioned were selected; more than 90% were notified by hospitals and mainly by highly specialized services. The number of deaths, which was low and varied rather irregularly at the beginning, then increased by successive stages. The first year, during which a tenth of deaths was recorded every three months, was followed by a great increase, doubling, then tripling the initial numbers. Lastly, a second and sudden rise occurred during the third trimester of 1985, the trimestrial number of deaths due to AIDS reaching 80.

  2. Enhanced electrocatalytic performance of Pt monolayer on nanoporous PdCu alloy for oxygen reduction

    Science.gov (United States)

    Hou, Linxi; Qiu, Huajun

    2012-10-01

    By selectively dealloying Al from PdxCu20-xAl80 ternary alloys in 1.0 M NaOH solution, nanoporous PdCu (np-PdCu) alloys with different Pd:Cu ratios are obtained. By a mild electrochemical dealloying treatment, the np-PdCu alloys are facilely converted into np-PdCu near-surface alloys with a nearly pure-Pd surface and PdCu alloy core. The np-PdCu near-surface alloys are then used as substrates to fabricate core-shell catalysts with a Pt monolayer as shell and np-PdCu as core by a Cu-underpotential deposition-Pt displacement strategy. Electrochemical measurements demonstrate that the Pt monolayer on np-Pd1Cu1 (Pt/np-Pd1Cu1) exhibits the highest Pt surface-specific activity towards oxygen reduction, which is ˜5.8-fold that of state-of-the-art Pt/C catalyst. The Pt/np-Pd1Cu1 also shows much enhanced stability with ˜78% active surface retained after 10,000 cycles (0.6-1.2 V vs. RHE). Under the same condition, the active surface of Pt/C drops to ˜28%.

  3. Computer aided control engineering

    DEFF Research Database (Denmark)

    Szymkat, Maciej; Ravn, Ole

    1997-01-01

    Current developments in the field of Computer Aided Control Engineering (CACE) have a visible impact on the design methodologies and the structure of the software tools supporting them. Today control engineers has at their disposal libraries, packages or programming environments that may be speci......Current developments in the field of Computer Aided Control Engineering (CACE) have a visible impact on the design methodologies and the structure of the software tools supporting them. Today control engineers has at their disposal libraries, packages or programming environments that may...

  4. Controlled Surface Segregation Leads to Efficient Coke-Resistant Nickel/Platinum Bimetallic Catalysts for the Dry Reforming of Methane

    Energy Technology Data Exchange (ETDEWEB)

    Li, Lidong [King Abdullah Univ. of Science and Technology, Thuwal (Saudi Arabia); Zhou, Lu [King Abdullah Univ. of Science and Technology, Thuwal (Saudi Arabia); Ould-Chikh, Samy [King Abdullah Univ. of Science and Technology, Thuwal (Saudi Arabia); Anjum, Dalaver H. [King Abdullah Univ. of Science and Technology, Thuwal (Saudi Arabia); Kanoun, Mohammed B. [King Abdullah Univ. of Science and Technology, Thuwal (Saudi Arabia); Scaranto, Jessica [SABIC Corporate Research and Innovation Center, Thuwal (Saudi Arabia); Hedhili, Mohamed N. [King Abdullah Univ. of Science and Technology, Thuwal (Saudi Arabia); Khalid, Syed [Brookhaven National Lab. (BNL), Upton, NY (United States); Laveille, Paco V. [King Abdullah Univ. of Science and Technology, Thuwal (Saudi Arabia); D' Souza, Lawrence [SABIC Corporate Research and Innovation Center, Thuwal (Saudi Arabia); Clo, Alain [King Abdullah Univ. of Science and Technology, Thuwal (Saudi Arabia); Basset, Jean-Marie [King Abdullah Univ. of Science and Technology, Thuwal (Saudi Arabia)

    2015-02-03

    The surface composition and structure are of vital importance for heterogeneous catalysts, especially for bimetallic catalysts, which often vary as a function of reaction conditions (known as surface segregation). The preparation of bimetallic catalysts with controlled metal surface composition and structure is very challenging. In this study, we synthesize a series of Ni/Pt bimetallic catalysts with controlled metal surface composition and structure using a method derived from surface organometallic chemistry. Moreover, the evolution of the surface composition and structure of the obtained bimetallic catalysts under simulated reaction conditions is investigated by various techniques, which include CO-probe IR spectroscopy, high-angle annular dark-field scanning transmission electron microscopy, energy-dispersive X-ray spectroscopy, extended X-ray absorption fine structure analysis, X-ray absorption near-edge structure analysis, XRD, and X-ray photoelectron spectroscopy. It is demonstrated that the structure of the bimetallic catalyst is evolved from Pt monolayer island-modified Ni nanoparticles to core–shell bimetallic nanoparticles composed of a Ni-rich core and a Ni/Pt alloy shell upon thermal treatment. The catalysts are active for the dry reforming of methane, and their catalytic activities, stabilities, and carbon formation vary with their surface composition and structure.

  5. Ductile transplutonium metal alloys

    Science.gov (United States)

    Conner, William V.

    1983-01-01

    Alloys of Ce with transplutonium metals such as Am, Cm, Bk and Cf have properties making them highly suitable as sources of the transplutonium element, e.g., for use in radiation detector technology or as radiation sources. The alloys are ductile, homogeneous, easy to prepare and have a fairly high density.

  6. Regeneration of Hydrotreating and FCC Catalysts

    Energy Technology Data Exchange (ETDEWEB)

    CM Wai; JG Frye; JL Fulton; LE Bowman; LJ Silva; MA Gerber

    1999-09-30

    Hydrotreating, hydrocracking, and fluid catalytic cracking (FCC) catalysts are important components of petroleum refining processes. Hydrotreating and hydrocracking catalysts are used to improve the yield of high-quality light oil fractions from heavier crude oil and petroleum feedstocks containing high levels of impurities. FCC catalysts improve the yield of higher octane gasoline from crude oil. Residuum hydrotreating and cracking catalysts are susceptible to irreversible deactivation caused by adsorption of sulfur and by metals impurities, such as vanadium and nickel. The gradual buildup of these impurities in a hydrotreating catalyst eventually plugs the pores and deactivates it. Nickel and vanadium adversely affect the behavior of cracking catalysts, reducing product yield and quality. Replacing deactivated catalysts represents a significant cost in petroleum refining. Equally important are the costs and potential liabilities associated with treating and disposing spent catalysts. For example, recent US Environmental Protection Agency rulings have listed spent hydrotreating and hydrorefining catalysts as hazardous wastes. FCC catalysts, though more easily disposed of as road-base or as filler in asphalt and cement, are still an economic concern mainly because of the large volumes of spent catalysts generated. New processes are being considered to increase the useful life of catalysts or for meeting more stringent disposal requirements for spent catalysts containing metals. This report discusses a collaborative effort between Pacific Northwest National Laboratory (PNNL) and Phillips Petroleum, Inc., to identify promising chemical processes for removing metals adhered to spent hydrodesulfurization (HDS, a type of hydrotreating catalyst) and FCC catalysts. This study, conducted by PNNL, was funded by the US Department of Energy's Bartlesville Project Office. Fresh and spent catalysts were provided by Phillips Petroleum. The FCC catalyst was a rare

  7. Mesoporous Pt and Pt/Ru alloy electrocatalysts for methanol oxidation

    Energy Technology Data Exchange (ETDEWEB)

    Franceschini, Esteban A. [Grupo de Celdas de Combustible, Departamento de Fisica de la Materia Condensada, Centro Atomico Constituyentes, CNEA. Av. General Paz 1499 (1650), San Martin, Buenos Aires (Argentina); Planes, Gabriel A. [Departamento de Quimica, Facultad de Ciencias Exactas, Fisicoquimicas y Naturales, Universidad Nacional de Rio Cuarto, Agencia Postal No 3, 5800, Rio Cuarto (Argentina); Williams, Federico J. [Departamento de Quimica Inorganica, Analitica y Quimica-Fisica, INQUIMAE CONICET, Facultad Ciencias Exactas y Naturales, Pabellon 2, Ciudad Universitaria, Buenos Aires (Argentina); Soler-Illia, Galo J.A.A. [Gerencia de Quimica, Centro Atomico Constituyentes, CNEA. Av. General Paz 1499 (1650), San Martin, Buenos Aires (Argentina); Corti, Horacio R. [Grupo de Celdas de Combustible, Departamento de Fisica de la Materia Condensada, Centro Atomico Constituyentes, CNEA. Av. General Paz 1499 (1650), San Martin, Buenos Aires (Argentina); Departamento de Quimica Inorganica, Analitica y Quimica-Fisica, INQUIMAE CONICET, Facultad Ciencias Exactas y Naturales, Pabellon 2, Ciudad Universitaria, Buenos Aires (Argentina)

    2011-02-15

    Mesoporous Pt and Pt/Ru catalysts with 2D-hexagonal mesostructure were synthesized using a triblock poly(ethylene oxide)-b-poly(propylene oxide)-b-poly(ethylene oxide) copolymer (Pluronic F127 {sup registered}) template, on a gold support. Large electrochemical surface areas were observed for the catalysts prepared at high overpotentials. Compared to the Pt catalyst, the Pt/Ru alloy containing 3 at% of Ru exhibited lower onset potential and more than three times the limit mass activity for methanol oxidation. This behavior is assigned to the larger pore size of the mesoporous Pt and Pt/Ru catalysts obtained with this template that seems to improve the methanol accessibility to the active sites compared to those obtained using lyotropic liquid crystals. (author)

  8. Catalyst containing oxygen transport membrane

    Energy Technology Data Exchange (ETDEWEB)

    Lane, Jonathan A.; Wilson, Jamie R.; Christie, Gervase Maxwell; Petigny, Nathalie; Sarantopoulos, Christos

    2017-02-07

    A composite oxygen transport membrane having a dense layer, a porous support layer and an intermediate porous layer located between the dense layer and the porous support layer. Both the dense layer and the intermediate porous layer are formed from an ionic conductive material to conduct oxygen ions and an electrically conductive material to conduct electrons. The porous support layer has a high permeability, high porosity, and a microstructure exhibiting substantially uniform pore size distribution as a result of using PMMA pore forming materials or a bi-modal particle size distribution of the porous support layer materials. Catalyst particles selected to promote oxidation of a combustible substance are located in the intermediate porous layer and in the porous support adjacent to the intermediate porous layer. The catalyst particles can be formed by wicking a solution of catalyst precursors through the porous support toward the intermediate porous layer.

  9. Catalyst containing oxygen transport membrane

    Science.gov (United States)

    Christie, Gervase Maxwell; Wilson, Jamie Robyn; van Hassel, Bart Antonie

    2012-12-04

    A composite oxygen transport membrane having a dense layer, a porous support layer and an intermediate porous layer located between the dense layer and the porous support layer. Both the dense layer and the intermediate porous layer are formed from an ionic conductive material to conduct oxygen ions and an electrically conductive material to conduct electrons. The porous support layer has a high permeability, high porosity, and a high average pore diameter and the intermediate porous layer has a lower permeability and lower pore diameter than the porous support layer. Catalyst particles selected to promote oxidation of a combustible substance are located in the intermediate porous layer and in the porous support adjacent to the intermediate porous layer. The catalyst particles can be formed by wicking a solution of catalyst precursors through the porous support toward the intermediate porous layer.

  10. Ultrahigh temperature intermetallic alloys

    Energy Technology Data Exchange (ETDEWEB)

    Brady, M.P.; Zhu, J.H.; Liu, C.T.; Tortorelli, P.F.; Wright, J.L.; Carmichael, C.A.; Walker, L.R. [Oak Ridge National Lab., TN (United States). Metals and Ceramics Div.

    1997-12-01

    A new family of Cr-Cr{sub 2}X based alloys with fabricability, mechanical properties, and oxidation resistance superior to previously developed Cr-Cr{sub 2}Nb and Cr-Cr{sub 2}Zr based alloys has been identified. The new alloys can be arc-melted/cast without cracking, and exhibit excellent room temperature and high-temperature tensile strengths. Preliminary evaluation of oxidation behavior at 1100 C in air indicates that the new Cr-Cr{sub 2}X based alloys form an adherent chromia-based scale. Under similar conditions, Cr-Cr{sub 2}Nb and Cr-Cr{sub 2}Zr based alloys suffer from extensive scale spallation.

  11. Optimal modifying and refining processes for A356 aluminium alloys

    Institute of Scientific and Technical Information of China (English)

    ZUO Xiu-rong; ZHONG Zhi-guo

    2006-01-01

    The influence of Ti, B, RE (cerium-rich mixtures of rare earth) and Sr, applied in modification and refining processes, on A356 aluminum alloys has been studied with the aids of OM, etc. The results show that the grain refining efficiency of Grain-Refining Aluminium Ingot (GRAI) and Al-Ti master alloys is similar. But the Ti addition from GRAI has lower costs than that with Al-Ti master alloys. So A356 aluminum alloys produced with GRAI are feasible in economy.Grain refining with GRAI with 0.01%Ti plus additional 0.03% B offers significant advantages over that from GRAI with 0.1% Ti only in A356 aluminum alloys, which made the dendrite α (Al) grain structure transform into equiaxed α (Al) grain structure, plus a partially modified eutectic silicon structure. RE addition to A356 aluminum alloys with Sr modifier is enable to achieve small DAS,reduced pores, well-refined fibrous silicon, small and dispersive eutectic colonies.

  12. Engineering Platinum Alloy Electrocatalysts in Nanoscale for PEMFC Application

    Energy Technology Data Exchange (ETDEWEB)

    He, Ting [Idaho National Laboratory

    2016-03-01

    Fuel cells are expected to be a key next-generation energy source used for vehicles and homes, offering high energy conversion efficiency and minimal pollutant emissions. However, due to large overpotentials on anode and cathode, the efficiency is still much lower than theoretically predicted. During the past decades, considerable efforts have been made to investigate synergy effect of platinum alloyed with base metals. But, engineering the alloy particles in nanoscale has been a challenge. Most important challenges in developing nanostructured materials are the abilities to control size, monodispersity, microcomposition, and even morphology or self-assembly capability, so called Nanomaterials-by-Design, which requires interdisciplinary collaborations among computational modeling, chemical synthesis, nanoscale characterization as well as manufacturing processing. Electrocatalysts, particularly fuel cell catalysts, are dramatically different from heterogeneous catalysts because the surface area in micropores cannot be electrochemically controlled on the same time scale as more transport accessible surfaces. Therefore, electrocatalytic architectures need minimal microporous surface area while maximizing surfaces accessible through mesopores or macropores, and to "pin" the most active, highest performance physicochemical state of the materials even when exposed to thermodynamic forces, which would otherwise drive restructuring, crystallization, or densification of the nanoscale materials. In this presentation, results of engineering nanoscale platinum alloy particles down to 2 ~ 4 nm will be discussed. Based on nature of alloyed base metals, various synthesis technologies have been studied and developed to achieve capabilities of controlling particle size and particle microcomposition, namely, core-shell synthesis, microemulsion technique, thermal decomposition process, surface organometallic chemical method, etc. The results show that by careful engineering the

  13. Mg based alloys obtained by mechanical alloying

    Energy Technology Data Exchange (ETDEWEB)

    Ordonez, S. [Univ. de Santiago de Chile (Chile). Fac. de Ingenieria; Garcia, G.; Serafini, D.; San Martin, A.

    1999-07-01

    In the present work, we studied the production of magnesium alloys, of stoichiometry 2Mg + Ni, by mechanical alloying (MA) and the behavior of the alloys under hydrogen in a Sievert`s type apparatus. The elemental powders were milled under argon atmosphere in a Spex 8000 high energy ball mill. The milled materials were characterized by X-ray diffraction (XRD) and scanning electron microscopy (SEM). Only minimum amounts of the Mg{sub 2}Ni intermetallic compound was obtained after 22 h of milling time. Most of the material was sticked to the inner surface of the container as well as to the milling balls. Powders milled only for 12 hours transforms to the intermetallic at around 433 K. Effects of the MA on the hydrogen absorption kinetics were also studied. (orig.) 10 refs.

  14. Studying Aid: Some Methods

    NARCIS (Netherlands)

    D.R. Gasper (Des)

    2003-01-01

    textabstractINVESTIGATING IDEAS, IDEOLOGIES AND PRACTICES This paper presents some methods for trying to make sense of international aid and of its study.1 Some of the methods may be deemed ethnographic; the others are important partners to them, but rather different. In the course of discussing q

  15. Hearing Aids Communication

    DEFF Research Database (Denmark)

    Globally, hearing loss is the second most frequent disability. About 80% of the persons affected by hearing loss do not use hearing aids. The goal of this edited volume is to present a theoretically founded, interdisciplinary approach geared at understanding and improving social interaction impac...

  16. Parent Hearing Aid Experiences

    Science.gov (United States)

    Munoz, Karen; Roberts, Mallory; Mullings, Day; Harward, Richard

    2012-01-01

    This study addresses parent experiences in obtaining and managing hearing aids for their young child. The purpose was to identify challenges parents encounter to determine what state agencies can do to improve parent access to amplification. Data were collected July through September of 2010; 40 parents of children ages birth to 3 years old…

  17. Hearing Aid Personalization

    DEFF Research Database (Denmark)

    Nielsen, Jens Brehm; Nielsen, Jakob; Jensen, Bjørn Sand

    2013-01-01

    Modern digital hearing aids require and offer a great level of personalization. Today, this personalization is not performed based directly on what the user actually perceives, but on a hearing-care professional’s interpretation of what the user explains about what is perceived. In this paper, an...

  18. Computer Aided Lecturing.

    Science.gov (United States)

    Van Meter, Donald E.

    1994-01-01

    Surveyed students taking a natural resource conservation course to determine the effects of computer software that provides tools for creating and managing visual presentations to students. Results indicated that 94% of the respondents believed computer-aided lectures helped them and recommended their continued use; note taking was more effective,…

  19. AIDS and associated malignancies

    Institute of Scientific and Technical Information of China (English)

    Charles WOOD; William HARRINGTON Jr

    2005-01-01

    AIDS associated malignancies (ARL) is a major complication associated with AIDS patients upon immunosuppression.Chronically immunocompromised patients have a markedly increased risk of developing lymphoproliferative disease. In the era of potent antiretrovirals therapy (ARV), the malignant complications due to HIV- 1 infection have decreased in developed nations where ARV is administered, but still poses a major problem in developing countries where HIV- 1incidence is high and ARV is still not yet widely available. Even in ARV treated individuals there is a concern that the prolonged survival of many HIV- 1 carriers is likely to eventually result in an increased number of malignancies diagnosed.Malignancies that were found to have high incidence in HIV-infected individuals are Kaposi's sarcoma (KS), Hodgkin's disease (HD) and non-Hodgkin's lymphoma (NHL). The incidence of NHL has increased nearly 200 fold in HIV-positive patients, and accounts for a greater percentage of AIDS defining illness in the US and Europe since the advent of HAART therapy. These AIDS related lymphomas are distinct from their counterparts seen in HIV- 1 seronegative patients.For example nearly half of all cases of ARL are associated with the presence of a gamma herpesvirus, Epstein Barr virus (EBV) or human herpesvirus-8 (HHV-8)/Kaposi's sarcoma associated herpesvirus (KSHV). The pathogenesis of ARLs is complex. B-cell proliferation driven by chronic antigenemia resulting in the induction of polyclonal and ultimately monoclonal lymphoproliferation may occur in the setting of severe immunosuppression.

  20. [Post-transfusional AIDS].

    Science.gov (United States)

    Azzini, M; Maccabruni, A; Marcellini, M; Michelone, G; Dei Cas, A

    1987-01-01

    Two cases of post-transfusional AIDS in two premature babies who received blood of the same seropositive donor, are reported. The risk of the susceptibility to HIV infection of these patients, in relation to the immaturity of immune system and to the transfusional treatment often necessary in premature newborns, is stressed.

  1. The CASPAR finding aids

    OpenAIRE

    Meghini, Carlo; Avancini, Henry; Versienti, Loredana

    2011-01-01

    One of the CASPAR key components is the FIND Components, which is implementing the Finding Aids of OAIS. According to OAIS, FIND manages Description Information that is associated to Information Packages in order to support the discovery of those Packages. FIND allows defining, creating, persisting, querying, browsing, and accessing both Description Information and the association between Information Packages and Description Information

  2. Coil Welding Aid

    Science.gov (United States)

    Wiesenbach, W. T.; Clark, M. C.

    1983-01-01

    Positioner holds coil inside cylinder during tack welding. Welding aid spaces turns of coil inside cylinder and applies contact pressure while coil is tack-welded to cylinder. Device facilitates fabrication of heat exchangers and other structures by eliminating hand-positioning and clamping of individual coil turns.

  3. Enteric parasites and AIDS

    Directory of Open Access Journals (Sweden)

    Sérgio Cimerman

    1999-11-01

    Full Text Available OBJECTIVE: To report on the importance of intestinal parasites in patients with AIDS, showing relevant data in the medical literature, with special emphasis on epidemiology, diagnosis and treatment of enteroparasitosis, especially cryptosporidiasis, isosporiasis, microsporidiasis and strongyloidiasis. DESIGN: Narrative review.

  4. deNOx catalysts for biomass combustion

    DEFF Research Database (Denmark)

    Kristensen, Steffen Buus

    industrial reference catalyst, after impregnation of 225 mole potassium/g of catalyst. A catalyst plate was synthesised using 20 wt.% sepiolite mixed with nano catalyst, supported by a SiO2-fibre mesh. Realistic potassium poisoning was performed on the catalyst plate, by exposure in a potassium aerosol...... for 632 hours at 350 C. Owing to physical blocking of potassium by sepiolite fibres the composite catalyst showed a further increase in potassium resistance compared with the unsupported catalyst. Finally a refined mechanism was proposed for the nano particle SCR catalyst explaining insitu FTIR...... observation done on the system. Most importantly it indicated that the V=O bond did not break during the SCR reaction, suggesting that another oxygen is responsible for the activity of the active vanadia site....

  5. Quick Guide to Flash Catalyst

    CERN Document Server

    Elmansy, Rafiq

    2011-01-01

    How do you transform user interface designs created in Photoshop or Illustrator into interactive web pages? It's easier than you think. This guide shows you how to use Adobe Flash Catalyst to create interactive UIs and website wireframes for Rich Internet Applications-without writing a single line of code. Ideal for web designers, this book introduces Flash Catalyst basics with detailed step-by-step instructions and screenshots that illustrate every part of the process. You'll learn hands-on how to turn your static design or artwork into working user interfaces that can be implemented in Fla

  6. Computational Chemistry-Based Identification of Ultra-Low Temperature Water-Gas-Shift Catalysts

    Energy Technology Data Exchange (ETDEWEB)

    Manos Mavrikakis

    2008-08-31

    The current work seeks to identify novel, catalytically-active, stable, poison-resistant LWGS catalysts that retain the superior activity typical of conventional Cu catalysts but can be operated at similar or lower temperatures. A database for the Binding Energies (BEs) of the LWGS relevant species, namely CO, O and OH on the most-stable, close-packed facets of a set of 17 catalytically relevant transition metals was established. This BE data and a database of previously established segregation energies was utilized to predict the stability of bimetallic NSAs that could be synthesized by combinations of the 17 parent transition metals. NSAs that were potentially stable both in vacuo and under the influence of strong-binding WGS intermediates were then selected for adsorption studies. A set of 40 NSAs were identified that satisfied all three screener criteria and the binding energies of CO, O and OH were calculated on a set of 66, 43 and 79 NSA candidates respectively. Several NSAs were found that bound intermediates weaker than the monometallic catalysts and were thus potentially poison-resistant. Finally, kinetic studies were performed and resulted in the discovery of a specific NSA-based bimetallic catalyst Cu/Pt that is potentially a promising LWGS catalyst. This stable Cu/Pt subsurface alloy is expected to provide facile H{sub 2}O activation and remain relatively resistant from the poisoning by CO, S and formate intermediates.

  7. Carbon-supported bimetallic Pd–Fe catalysts for vapor-phase hydrodeoxygenation of guaiacol

    Energy Technology Data Exchange (ETDEWEB)

    Sun, Junming; Karim, Ayman M.; Zhang, He; Kovarik, Libor; Li, Xiaohong Shari; Hensley, Alyssa J.; McEwen, Jean-Sabin; Wang, Yong

    2013-10-01

    Abstract Carbon supported metal catalysts (Cu/C, Fe/C, Pd/C, Pt/C, PdFe/C and Ru/C) have been prepared, characterized and tested for vapor-phase hydrodeoxygenation (HDO) of guaiacol (GUA) at atmospheric pressure. Phenol was the major intermediate on all catalysts. Over the noble metal catalysts saturation of the aromatic ring was the major pathway observed at low temperature (250 °C), forming predominantly cyclohexanone and cyclohexanol. Substantial ring opening reaction was observed on Pt/C and Ru/C at higher reaction temperatures (e.g., 350 °C). Base metal catalysts, especially Fe/C, were found to exhibit high HDO activity without ring-saturation or ring-opening with the main products being benzene, phenol along with small amounts of cresol, toluene and trimethylbenzene (TMB). A substantial enhancement in HDO activity was observed on the PdFe/C catalysts. Compared with Fe/C, the yield to oxygen-free aromatic products (i.e., benzene/toluene/TMB) on PdFe/C increased by a factor of four at 350 °C, and by approximately a factor of two (83.2% versus 43.3%) at 450 °C. The enhanced activity of PdFe/C is attributed to the formation of PdFe alloy as evidenced by STEM, EDS and TPR.

  8. Hydrogen generation from decomposition of hydrous hydrazine over Ni-Ir/CeO2 catalyst

    Directory of Open Access Journals (Sweden)

    Hongbin Dai

    2017-02-01

    Full Text Available The synthesis of highly active and selective catalysts is the central issue in the development of hydrous hydrazine (N2H4·H2O as a viable hydrogen carrier. Herein, we report the synthesis of bimetallic Ni-Ir nanocatalyts supported on CeO2 using a one-pot coprecipitation method. A combination of XRD, HRTEM and XPS analyses indicate that the Ni-Ir/CeO2 catalyst is composed of tiny Ni-Ir alloy nanoparticles with an average size of around 4 nm and crystalline CeO2 matrix. The Ni-Ir/CeO2 catalyst exhibits high catalytic activity and excellent selectivity towards hydrogen generation from N2H4·H2O at mild temperatures. Furthermore, in contrast to previously reported Ni-Pt catalysts, the Ni-Ir/CeO2 catalyst shows an alleviated requirement on alkali promoter to achieve its optimal catalytic performance.

  9. Screening for AIDS.

    Science.gov (United States)

    1985-03-29

    Tests to detect serum antibody to human T-lymphotropic virus type III (HTLV-III), based on an enzyme-linked immunosorbent assay (ELISA) that uses whole disrupted HTLV-III virus antigens, are now commercially available in the US. Recent surveys of groups at high risk for acquired immunodeficiency syndrome (AIDS) have found that 22-65% of homosexual men, 87% of active intravenous drug users, 56-72% of hemophiliacs, and 35% of women who were sexual partners of men with AIDS have had postitive ELISA tests compared with fewer than 1% of those with no known risk factors. A positive ELISA test could be due to subclinical infection, immunity, or cross-reactivity with other viral antigens. Laboratory error can also produce false positive results. Thus, it is recommended that the ELISA test be repeated at least once on all seropositive specimens before the result is reported to the patient. The western blot test appears to be more specific and less sensitive than the ELISA. Studies of asymptomatic seropositive homosexual men followed for 2-5 years have found that over 50% remain asymptomatic, 5-19% develop full blown AIDS, and 25% develop signs suggestive of the AIDS-related complex. Asymptomatic patients with positive ELISA tests should be made aware of early signs and symptoms of AIDS. Other data suggest that seropositive patients have the HTLV-III virus in their blood, semen, and/or saliva and can transmit the infection. Precautions to prevent transmission, such as the use of condoms, should be taken by such patients. Physicians should be sensitive to the fear and anxiety that a positive ELISA test will create.

  10. Monte Carlo Simulation of Alloy Design Techniques: Fracture and Welding Studied Using the BFS Method for Alloys

    Science.gov (United States)

    Bozzolo, Guillermo H.; Good, Brian; Noebe, Ronald D.; Honecy, Frank; Abel, Phillip

    1999-01-01

    Large-scale simulations of dynamic processes at the atomic level have developed into one of the main areas of work in computational materials science. Until recently, severe computational restrictions, as well as the lack of accurate methods for calculating the energetics, resulted in slower growth in the area than that required by current alloy design programs. The Computational Materials Group at the NASA Lewis Research Center is devoted to the development of powerful, accurate, economical tools to aid in alloy design. These include the BFS (Bozzolo, Ferrante, and Smith) method for alloys (ref. 1) and the development of dedicated software for large-scale simulations based on Monte Carlo- Metropolis numerical techniques, as well as state-of-the-art visualization methods. Our previous effort linking theoretical and computational modeling resulted in the successful prediction of the microstructure of a five-element intermetallic alloy, in excellent agreement with experimental results (refs. 2 and 3). This effort also produced a complete description of the role of alloying additions in intermetallic binary, ternary, and higher order alloys (ref. 4).

  11. On-line regeneration of hydrodesulfurization catalyst

    Science.gov (United States)

    Preston, Jr., John L.

    1980-01-01

    A hydrotreating catalyst is regenerated as it concurrently hydrotreats a hydrocarbon fuel by introducing a low concentration of oxygen into the catalyst bed either continuously or periodically. At low oxygen concentrations the carbon deposits on the catalyst are burned off without harming the catalyst and without significantly affecting the hydrotreating process. In a preferred embodiment the hydrotreating process is hydrodesulfurization, and regenerating is done periodically with oxygen concentrations between 0.1 and 0.5 volume percent.

  12. Bifunctional heterogeneous catalysts from oil palm empty fruit bunches ash and alum for biodiesel synthesis simultaneously

    Science.gov (United States)

    Astar, Ismail; Usman, Thamrin; Wahyuni, Nelly; Rudiyansyah, Alimuddin, Andi Hairil

    2017-03-01

    Free fatty acids (FFA) contained in crude palm oil (CPO) and sludge oil has been used as the base material of biodiesel with the aid of a catalyst in the transesterification and esterification reactions. This study aims to synthesize and characterize bifunctional catalysts were synthesized from the ashes of palm empty fruit bunches (EFB) and alum based on the analysis of XRD, XRF and acidity test. Bifunctional catalyst obtained was used as a catalyst to production of biodiesel with different levels of FFA. The optimum ratio alum added was 0.2 mol at 3 hours of reaction time and 3% of catalyst by the FFA samples were used 67,40%. The catalyst with optimum alum mole variations subsequently used on samples with varying levels of FFA, namely 1.29%, 4.98%, 29.21%, 67.40% and 74.47%. Optimum conversion of methyl ester in the esterification reaction occurs in the sample with 67.40% FFA content, which reached 86.17%, while the conversion of methyl ester transesterification process optimum amounted to 45.70% in the samples with 4.98% FFA content. Methyl ester produced has a refractive index of 1.448 (29.8 ° C), density of 0.883 g / mL (25 °C) and a viscosity of 8.933 cSt (25 ° C). The results of GC-MS analysis showed that the main composition of methyl ester result of esterification of sludge oil methyl palmitate (36.84%), while the CPO transesterification shows the main composition of methyl ester is methyl oleic (38.87%). Based on the research results, the catalyst synthesized from alum and EFB ash can be used as a Bifunctional catalysts for biodiesel synthesis.

  13. Henan Surveys Blood Donors to Aid AIDS Prevention

    Institute of Scientific and Technical Information of China (English)

    2004-01-01

    Central China's Henan Province, one of the worst AIDS-hit provinces in the country, launched a sweeping survey in September of past blood donors to ascertain tile number of HIV-infected individuals to aid AIDS prevention and control work.

  14. Perceptions of Aid and Actual Aid in Intergenerational Caregiving.

    Science.gov (United States)

    Walker, Alexis J.; And Others

    1991-01-01

    Compared pairs (n=174) of elderly mothers' and their caregiving daughters' perceptions of aid given to the mothers with actual caregiving activities. Results indicated nearly half of the mothers and daughters were accurate in their perceptions of aid given to the mothers; when mothers' perception of aid was inaccurate, mothers overestimated rather…

  15. Novel non-platinum metal catalyst material

    DEFF Research Database (Denmark)

    2014-01-01

    The present invention relates to a novel non-platinum metal catalyst material for use in low temperature fuel cells and electrolysers and to fuel cells and electrolysers comprising the novel non-platinum metal catalyst material. The present invention also relates to a novel method for synthesizing...... the novel non-platinum metal catalyst material....

  16. Catalysts and methods of using the same

    Energy Technology Data Exchange (ETDEWEB)

    Slowing, Igor Ivan; Kandel, Kapil

    2017-02-14

    The present invention provides a catalyst including a mesoporous silica nanoparticle and a catalytic material comprising iron. In various embodiments, the present invention provides methods of using and making the catalyst. In some examples, the catalyst can be used to hydrotreat fatty acids or to selectively remove fatty acids from feedstocks.

  17. Efficient epoxidation of propene using molecular catalysts

    DEFF Research Database (Denmark)

    Markovits, Iulius I. E.; Anthofer, Michael H.; Kolding, Helene

    2014-01-01

    The epoxidation of propene is performed in homogeneous phase using various molecular catalysts and H2O2 or tert-butyl hydroperoxide as oxidants. A comparison between some molybdenum catalysts and methyltrioxorhenium (MTO) shows that the well known Re catalyst is the best among the examined...

  18. Direct decomposition of methane over SBA-15 supported Ni, Co and Fe based bimetallic catalysts

    Science.gov (United States)

    Pudukudy, Manoj; Yaakob, Zahira; Akmal, Zubair Shamsul

    2015-03-01

    Thermocatalytic decomposition of methane is an alternative route for the production of COx-free hydrogen and carbon nanomaterials. In this work, a set of novel Ni, Co and Fe based bimetallic catalysts supported over mesoporous SBA-15 was synthesized by a facile wet impregnation route, characterized for their structural, textural and reduction properties and were successfully used for the methane decomposition. The fine dispersion of metal oxide particles on the surface of SBA-15, without affecting its mesoporous texture was clearly shown in the low angle X-ray diffraction patterns and the transmission electron microscopy (TEM) images. The nitrogen sorption analysis showed the reduced specific surface area and pore volume of SBA-15, after metal loading due to the partial filling of hexagonal mesopores by metal species. The results of methane decomposition experiments indicated that all of the bimetallic catalysts were highly active and stable for the reaction at 700 °C even after 300 min of time on stream (TOS). However, a maximum hydrogen yield of ∼56% was observed for the NiCo/SBA-15 catalyst within 30 min of TOS. A high catalytic stability was shown by the CoFe/SBA-15 catalyst with 51% of hydrogen yield during the course of reaction. The catalytic stability of the bimetallic catalysts was attributed to the formation of bimetallic alloys. Moreover, the deposited carbons were found to be in the form of a new set of hollow multi-walled nanotubes with open tips, indicating a base growth mechanism, which confirm the selectivity of SBA-15 supported bimetallic catalysts for the formation of open tip carbon nanotubes. The Raman spectroscopic and thermogravimetric analysis of the deposited carbon nanotubes over the bimetallic catalysts indicated their higher graphitization degree and oxidation stability.

  19. Single-Atom Catalyst of Platinum Supported on Titanium Nitride for Selective Electrochemical Reactions.

    Science.gov (United States)

    Yang, Sungeun; Kim, Jiwhan; Tak, Young Joo; Soon, Aloysius; Lee, Hyunjoo

    2016-02-05

    As a catalyst, single-atom platinum may provide an ideal structure for platinum minimization. Herein, a single-atom catalyst of platinum supported on titanium nitride nanoparticles were successfully prepared with the aid of chlorine ligands. Unlike platinum nanoparticles, the single-atom active sites predominantly produced hydrogen peroxide in the electrochemical oxygen reduction with the highest mass activity reported so far. The electrocatalytic oxidation of small organic molecules, such as formic acid and methanol, also exhibited unique selectivity on the single-atom platinum catalyst. A lack of platinum ensemble sites changed the reaction pathway for the oxygen-reduction reaction toward a two-electron pathway and formic acid oxidation toward direct dehydrogenation, and also induced no activity for the methanol oxidation. This work demonstrates that single-atom platinum can be an efficient electrocatalyst with high mass activity and unique selectivity.

  20. Tunable magnetocaloric effect in transition metal alloys.

    Science.gov (United States)

    Belyea, Dustin D; Lucas, M S; Michel, E; Horwath, J; Miller, Casey W

    2015-10-28

    The unpredictability of geopolitical tensions and resulting supply chain and pricing instabilities make it imperative to explore rare earth free magnetic materials. As such, we have investigated fully transition metal based "high entropy alloys" in the context of the magnetocaloric effect. We find the NiFeCoCrPdx family exhibits a second order magnetic phase transition whose critical temperature is tunable from 100 K to well above room temperature. The system notably displays changes in the functionality of the magnetic entropy change depending on x, which leads to nearly 40% enhancement of the refrigerant capacity. A detailed statistical analysis of the universal scaling behavior provides direct evidence that heat treatment and Pd additions reduce the distribution of exchange energies in the system, leading to a more magnetically homogeneous alloy. The general implications of this work are that the parent NiFeCoCr compound can be tuned dramatically with FCC metal additives. Together with their relatively lower cost, their superior mechanical properties that aid manufacturability and their relative chemical inertness that aids product longevity, NiFeCoCr-based materials could ultimately lead to commercially viable magnetic refrigerants.

  1. Transformation of bulk alloys to oxide nanowires

    Science.gov (United States)

    Lei, Danni; Benson, Jim; Magasinski, Alexandre; Berdichevsky, Gene; Yushin, Gleb

    2017-01-01

    One dimensional (1D) nanostructures offer prospects for enhancing the electrical, thermal, and mechanical properties of a broad range of functional materials and composites, but their synthesis methods are typically elaborate and expensive. We demonstrate a direct transformation of bulk materials into nanowires under ambient conditions without the use of catalysts or any external stimuli. The nanowires form via minimization of strain energy at the boundary of a chemical reaction front. We show the transformation of multimicrometer-sized particles of aluminum or magnesium alloys into alkoxide nanowires of tunable dimensions, which are converted into oxide nanowires upon heating in air. Fabricated separators based on aluminum oxide nanowires enhanced the safety and rate capabilities of lithium-ion batteries. The reported approach allows ultralow-cost scalable synthesis of 1D materials and membranes.

  2. What Is HIV/AIDS?

    Science.gov (United States)

    ... AIDS? Subscribe Translate Text Size Print What Is HIV/AIDS? Human Immunodeficiency Virus (HIV) HIV stands for human immunodeficiency virus. If left ... need medical treatment to prevent death. Where DId HIV Come From? Scientists identified a type of chimpanzee ...

  3. HIV / AIDS: An Unequal Burden

    Science.gov (United States)

    Skip Navigation Bar Home Current Issue Past Issues HIV / AIDS HIV / AIDS: An Unequal Burden Past Issues / Summer 2009 ... high-risk category, emphasizes Dr. Cargill. Photo: iStock HIV and Pregnancy Are there ways to help HIV- ...

  4. Does Corruption Cause Aid Fatigue?

    DEFF Research Database (Denmark)

    Bauhr, Monika; Charron, Nicholas; Nasiritousi, Naghmeh

    2013-01-01

    Does perceived corruption in recipient countries reduce support for foreign aid in donor countries? This under-explored yet salient question is examined using the 2009 Eurobarometer survey for the 27 EU countries. We suggest that perceived corruption can cause aid fatigue but that this relationship...... is highly contextualized. The results show that perceptions about corruption in developing countries reduce overall support for aid among respondents in donor countries. However, this effect is mitigated by country and contextual-level effects and different understandings of what we call the “aid-corruption...... paradox,” namely that the need for foreign aid is often the greatest in corrupt environments. Three different dynamics of the aid-corruption paradox influence support for aid: moral, pragmatic, and strategic understandings. In EU-15 countries, the effect of perceived corruption in recipient states on aid...

  5. Corrosion Behaviour of Zn-10Al-1.5Cu Alloy

    Directory of Open Access Journals (Sweden)

    C. N. Panagopoulos

    2011-01-01

    Full Text Available The corrosion behaviour of Zn-10Al-1.5Cu alloy in NaCl solution was examined. The used NaCl solution concentrations were 1M, 0.3M, and 0.003M for a constant temperature values of 7°C or 25°C or 45°C. The corrosion behaviour of this alloy was investigated under potentiodynamic corrosion conditions. The surface of the corroded alloy specimens was studied with the aid of scanning electron microscopy and X-ray diffraction techniques. It was observed that the increase of NaCl concentration in the corrosion solution for a constant value of temperature led to lower corrosion resistance of the alloy. For a constant value of solution concentration, the increase of solution temperature also led to the decrease of corrosion resistance of the same alloy.

  6. Stabilizing the body centered cubic crystal in titanium alloys by a nano-scale concentration modulation

    Energy Technology Data Exchange (ETDEWEB)

    Wang, H. L.; Shah, S. A. A.; Hao, Y. L.; Prima, F.; Li, T.; Cairney, J. M.; Wang, Y. D.; Wang, Y.; Obbard, E. G.; Li, S. J.; Yang, R.

    2017-04-01

    It is well-known that the body centered cubic (bcc) crystal in titanium alloys reaches its stability limit as the electron-to-atom (e/a) ratio of the alloy drops down to ~4.24. This critical value, however, is much higher than that of a multifunctional bcc type alloy (e/a = 4.15). Here we demonstrate that a nano-scale concentration modulation created by spinodal decomposition is what stabilizes the bcc crystal of the alloy. Aided by such a nano-scale concentration heterogeneity, unexpected properties from its chemically homogeneous counterpart are obtained. This provides a new strategy to design functional titanium alloys by tuning the spinodal decomposition.

  7. Highly Active Carbon Supported Pd-Ag Nanofacets Catalysts for Hydrogen Production from HCOOH.

    Science.gov (United States)

    Wang, Wenhui; He, Ting; Liu, Xuehua; He, Weina; Cong, Hengjiang; Shen, Yangbin; Yan, Liuming; Zhang, Xuetong; Zhang, Jinping; Zhou, Xiaochun

    2016-08-17

    Hydrogen is regarded as a future sustainable and clean energy carrier. Formic acid is a safe and sustainable hydrogen storage medium with many advantages, including high hydrogen content, nontoxicity, and low cost. In this work, a series of highly active catalysts for hydrogen production from formic acid are successfully synthesized by controllably depositing Pd onto Ag nanoplates with different Ag nanofacets, such as Ag{111}, Ag{100}, and the nanofacet on hexagonal close packing Ag crystal (Ag{hcp}). Then, the Pd-Ag nanoplate catalysts are supported on Vulcan XC-72 carbon black to prevent the aggregation of the catalysts. The research reveals that the high activity is attributed to the formation of Pd-Ag alloy nanofacets, such as Pd-Ag{111}, Pd-Ag{100}, and Pd-Ag{hcp}. The activity order of these Pd-decorated Ag nanofacets is Pd-Ag{hcp} > Pd-Ag{111} > Pd-Ag{100}. Particularly, the activity of Pd-Ag{hcp} is up to an extremely high value, i.e., TOF{hcp} = 19 000 ± 1630 h(-1) at 90 °C (lower limit value), which is more than 800 times higher than our previous quasi-spherical Pd-Ag alloy nanocatalyst. The initial activity of Pd-Ag{hcp} even reaches (3.13 ± 0.19) × 10(6) h(-1) at 90 °C. This research not only presents highly active catalysts for hydrogen generation but also shows that the facet on the hcp Ag crystal can act as a potentially highly active catalyst.

  8. Perovskite catalysts for oxidative coupling

    Science.gov (United States)

    Campbell, Kenneth D.

    1991-01-01

    Perovskites of the structure A.sub.2 B.sub.2 C.sub.3 O.sub.10 are useful as catalysts for the oxidative coupling of lower alkane to heavier hydrocarbons. A is alkali metal; B is lanthanide or lanthanum, cerium, neodymium, samarium, praseodymium, gadolinium or dysprosium; and C is titanium.

  9. Biodiesel production using heterogenous catalyst

    Science.gov (United States)

    The current transesterification of triacylglycerides (TAG) to produce biodiesel is based on the homogenous catalyst method using strong base such as hydroxides or methoxides. However, this method results in a number of problems: (1) acid pre-treatment is required of feedstocks high in free fatty ac...

  10. TUNGSTEN BASE ALLOYS

    Science.gov (United States)

    Schell, D.H.; Sheinberg, H.

    1959-12-15

    A high-density quaternary tungsten-base alloy having high mechanical strength and good machinability composed of about 2 wt.% Ni, 3 wt.% Cu, 5 wt.% Pb, and 90wt.% W is described. This alloy can be formed by the powder metallurgy technique of hot pressing in a graphite die without causing a reaction between charge and the die and without formation of a carbide case on the final compact, thereby enabling re-use of the graphite die. The alloy is formable at hot- pressing temperatures of from about 1200 to about 1350 deg C. In addition, there is little component shrinkage, thereby eliminating the necessity of subsequent extensive surface machining.

  11. Facile Fabrication of Platinum-Cobalt Alloy Nanoparticles with Enhanced Electrocatalytic Activity for a Methanol Oxidation Reaction

    Science.gov (United States)

    Huang, Huihong; Hu, Xiulan; Zhang, Jianbo; Su, Nan; Cheng, JieXu

    2017-01-01

    Decreasing the cost associated with platinum-based catalysts along with improving their catalytic properties is a major challenge for commercial direct methanol fuel cells. In this work, a simple and facile strategy was developed for the more efficient preparation of multi-walled carbon nanotube (MWCNT) -supported Pt/CoPt composite nanoparticles (NPs) via solution plasma sputtering with subsequent thermal annealing. Quite different from general wet synthesis methods, Pt/CoPt composite NPs were directly derived from metal wire electrodes without any additions. The obtained Pt/CoPt/MWCNTs composite catalysts exhibited tremendous improvement in the electro-oxidation of methanol in acidic media with mass activities of 1719 mA mg−1Pt. This value is much higher than that of previous reports of Pt-Co alloy and commercial Pt/C (3.16 times) because of the many active sites and clean surface of the catalysts. The catalysts showed good stability due to the special synergistic effects of the CoPt alloy. Pt/CoPt/MWCNTs can be used as a promising catalyst for direct methanol fuel cells. In addition, this solution plasma sputtering-assisted synthesis method introduces a general and feasible route for the synthesis of binary alloys. PMID:28358143

  12. How Do People Get AIDS?

    Science.gov (United States)

    ... of Healthy Breakfasts Shyness How Do People Get AIDS? KidsHealth > For Teens > How Do People Get AIDS? A A A en español ¿Cómo contrae alguien el SIDA? AIDS stands for acquired immunodeficiency syndrome , a disease that ...

  13. Cerebral toxoplasmosis in AIDS

    Energy Technology Data Exchange (ETDEWEB)

    Christ, F.; Steudel, H.; Klotz, D.

    1986-02-01

    Since 1982 (Hauser and co-workers), literature has reported focal cerebral tissue charges in AIDS patients whose diagnosis was unclear at first but which could be identified finally as florid toxoplasmosis encephalitis by biopsy and autopsy. It was found that the value of otherwise reliable serological tests (KBR, Sabin-Feldmann tests, etc.) is questionable in patients with severely impaired or incompetent immune systems, and, in particular, that a negative or uncharacteristic test result may not preclude any opportunistic infection process. Furthermore, isolation of Toxoplasma gondii or specific antibodies from the cerebrospinal fluid will be successful in exceptional cases only. In patients with AIDS or lymphadenopathy syndrome, the differential diagnosis will have to include - first and foremost - reactivated toxoplasma infection (not newly acquired, as a rule) if central neurological symptoms occur.

  14. Mutual aid fund commission

    CERN Multimedia

    Staff Association

    2011-01-01

    The composition of the Board of the Mutual Aid Fund for 2011 is as follows: President: Pascal Droux Vice-president: Connie Potter Treasurer: Louis Pereira Deputy treasurer: Barbara Brugger Secretary: Sonia Casenove Deputy secretary: Isabelle Mardirossian Members: Christopher David Thomas   Jean-Claude Vialis (GAC member)   Marie-Luce Falipou   Gunilla Santiard (Jean-Claude Vialis’s alternate) The role of the Fund is to provide financial help to members of personnel and beneficiaries of the Pension Fund who are in need of exceptional financial assistance. All requests are treated in the strictest confidence. Should you wish to apply for aid from the Fund, kindly contact any member of the Board as given above or Social Services, tel.74479 – 73867.

  15. Mycobacterial Infections in AIDS

    Directory of Open Access Journals (Sweden)

    A Ross Hill

    1991-01-01

    Full Text Available Tuberculosis (TB remains uniquely important among acquired immune deficiency syndrome (AIDS-associated opportunistic infections: it presents the greatest public health hazard worldwide, is the most readily curable, and is largely preventable with existing means. Given the expanding pool of human immunodeficiency virus (HIV seropositive persons, particularly in developing nations where Mycobacterium tuberculosis remains a leading health problem, one can expect a continued rise in TB cases during the 1990s. Global efforts to eliminate TB are now inextricably entwined with the effectiveness of measures to curtail the HIV epidemic. Mycobacterium avium complex infection, currently an intractable late complication of aids, may increase in clinical importance as success in managing other opportunistic infections and HIV disease itself improves. Understanding of the pathogenesis and management of mycobacterial diseases should increase rapidly given the renewed research spurred on by the advent of HIV.

  16. Standard Specification for Copper-Aluminum-Silicon-Cobalt Alloy, Copper-Nickel-Silicon-Magnesium Alloy, Copper-Nickel-Silicon Alloy, Copper-Nickel-Aluminum-Magnesium Alloy, and Copper-Nickel-Tin Alloy Sheet and Strip

    CERN Document Server

    American Society for Testing and Materials. Philadelphia

    2015-01-01

    Standard Specification for Copper-Aluminum-Silicon-Cobalt Alloy, Copper-Nickel-Silicon-Magnesium Alloy, Copper-Nickel-Silicon Alloy, Copper-Nickel-Aluminum-Magnesium Alloy, and Copper-Nickel-Tin Alloy Sheet and Strip

  17. Pulmonary mycosis in AIDS

    Energy Technology Data Exchange (ETDEWEB)

    Busi Rizzi, Elisa; Schinina, Vincenzo; Bellussi, Angelo; De Santis, Andrea; Mazzuoli, Giovanna; Giosue, Sandro; Bibbolino, Corrado

    2001-01-01

    We retrospectively reviewed our series of 35 pulmonary mycosis in patients with AIDS, observed from 1987 to 1999, to correlate the imaging and pathologic findings. We further evaluated the frequency of fungal pneumonia before and after the use of a highly active antiretroviral therapy (HAART). Early recognition of pulmonary mycosis is imperative in these patients and improved survival can be achieved with early CT detection and prompt institution of high-dose antifungal therapy.

  18. Computer aided manipulator control

    Science.gov (United States)

    Bejczy, A. K.; Zawacki, R. L.

    1980-01-01

    This paper describes the hardware and software system of a dedicated mini- and microcomputer network developed at the JPL teleoperator project to aid the operator in real-time control of remote manipulators. The operator can be in series or in parallel with the control computer during operation. The purpose of the project is to develop, demonstrate and evaluate advanced supervisory control concepts and techniques for space applications. The paper concludes with a brief outline of future development plans and issues.

  19. Computer aided product design

    DEFF Research Database (Denmark)

    Constantinou, Leonidas; Bagherpour, Khosrow; Gani, Rafiqul

    1996-01-01

    A general methodology for Computer Aided Product Design (CAPD) with specified property constraints which is capable of solving a large range of problems is presented. The methodology employs the group contribution approach, generates acyclic, cyclic and aromatic compounds of various degrees......-liquid equilibria (LLE), solid-liquid equilibria (SLE) and gas solubility. Finally, a computer program based on the extended methodology has been developed and the results from five case studies highlighting various features of the methodology are presented....

  20. Nutritional anemia and AIDS

    OpenAIRE

    Ruíz, Óscar; Instituto de Investigaciones Clínicas, UNMSM; Díaz, David; Instituto de Investigaciones Clínicas, Facultad de Medicina, UNMSM, y Hospital Nacional Dos de Mayo; Castillo, Óscar; Instituto de Investigaciones Clínicas, UNMSM; Reyes, Rafael; Instituto de Investigaciones Clínicas, UNMSM; Marangoni, Manuela; Programa PROCETSS, Hospital Nacional Dos de Mayo; Ronceros, Gerardo; Instituto de Investigaciones Clínicas, Facultad de Medicina, UNMSM

    2013-01-01

    Objectives: To determine the type of anemia most frequent in patients with AIDS and the various degrees of anemia. Material and methods: One hundred patients 18 to 60 year-old infected with human immune deficiency virus (HIV) with residence in Lima and Callao were studied from January to December 2001 for blood count bone marrow aspiration, serum iron, transferrin, ferritin, folate and vitamin B12 levels. Samples were evaluated at the “Dos de Mayo” Hospital Clinical Pathology Department. Resu...

  1. Transitional justice and aid

    OpenAIRE

    Hellsten, Sirkku K.

    2012-01-01

    This paper examines the current security-governance-development nexus, something that is often also discussed under the concept of transitional justice (TJ). The paper analyses how the ambiguous, evolving and expanding nature of the concept of TJ affects the planning, coordination, evaluation and assessment of aid given to conflict ridden, post-conflict or (post) authoritarian societies in order to strengthen their democracy. Special attention is paid to gender justice. Illustrations are draw...

  2. HIV/AIDS eradication

    OpenAIRE

    Marsden, Matthew D.; Zack, Jerome A.

    2013-01-01

    Antiretroviral therapy can inhibit HIV replication in patients and prevent progression to AIDS. However, it is not curative. Here we provide an overview of what antiretroviral drugs do and how the virus persists during therapy in rare reservoirs, such as latently infected CD4+ T cells. We also outline several innovative methods that are currently under development to eradicate HIV from infected individuals. These strategies include gene therapy approaches intended to create an HIV-resistant i...

  3. MECHANICAL STRENGTH AND RELIABILITY OF SOLID CATALYSTS

    Institute of Scientific and Technical Information of China (English)

    Yongdan Li; Dongfang Wu; Y.S. Lin

    2004-01-01

    The mechanical strength of solid catalysts is one of the key parameters for reliable and efficient performance of a fixed bed reactor. Some recent developments and their basic mechanics within this context are reviewed. The main concepts discussed are brittle fracture which leads to the mechanical failure of the catalyst pellets, measurement and statistical properties of the catalyst strength data, and mechanical reliability of the catalyst pellets and their packed bed. The scientific basis for the issues on the catalyst mechanical properties calls yet for further elucidation and advancement.

  4. Has aid for AIDS raised all health funding boats?

    Science.gov (United States)

    Shiffman, Jeremy; Berlan, David; Hafner, Tamara

    2009-11-01

    Global health analysts have debated whether donor prioritization of HIV/AIDS control has lifted all boats, raising attention and funding levels for health issues aside from HIV/AIDS. We investigate this question, considering donor funding for 4 historically prominent health agendas-HIV/AIDS, health systems strengthening, population and reproductive health, and infectious disease control-over the decade 1998-2007. We employ funding data from the Development Assistance Committee of the Organization for Economic Cooperation and Development, which tracks donor aid. The data indicate that HIV/AIDS may have helped to increase funding for the control of other infectious diseases; however, there is no firm evidence that other health issues beyond the control of infectious diseases have benefited. Between 1998 and 2007, funding for HIV/AIDS control rose from just 5.5% to nearly half of all aid for health. Over the same period, funding for health systems strengthening declined from 62.3% to 23.9% of total health aid and that for population and reproductive health declined from 26.4% to 12.3%. Also, even as total aid for health tripled during this decade, aid for health systems strengthening largely stagnated. Overall, the data indicate little support for the contention that donor funding for HIV/AIDS has lifted all boats.

  5. AIDS and Africa. Introduction.

    Science.gov (United States)

    Kopelman, Loretta M; van Niekerk, Anton A

    2002-04-01

    Sub-Saharan Africa is the epicenter of the HIV/AIDS epidemic, and in this issue of the Journal, seven authors discuss the moral, social and medical implications of having 70% of those stricken living in this area. Anton A. van Niekerk considers complexities of plague in this region (poverty, denial, poor leadership, illiteracy, women's vulnerability, and disenchantment of intimacy) and the importance of finding responses that empower its people. Solomon Benatar reinforces these issues, but also discusses the role of global politics in sub-Saharan Africa, especially discrimination, imperialism and its exploitation by first world countries. Given the public health crisis, Udo Schüklenk and Richard E. Ashcroft defend compulsory licensing of essential HIV/AIDS medications on consequentialist grounds. Keymanthri Moodley discusses the importance of conducting research and the need to understand a moderate form of communitarianism, also referred to as "ubuntu" or "communalism", to help some Africans understand research as an altruistic endeavour. Godfrey B. Tangwa also defends traditional African values of empathy and ubuntu, discussing how they should be enlisted to fight this pandemic. Loretta M. Kopelman criticizes the tendency among those outside Africa to dismiss the HIV/AIDS pandemic, attributing one source to the ubiquitous and misguided punishment theory of disease. The authors conclude that good solutions must be cooperative ventures among countries within and outside of sub-Saharan Africa with far more support from wealthy countries.

  6. Aid Supplies Over Time

    DEFF Research Database (Denmark)

    Jones, Edward Samuel

    The recent financial crisis has rekindled interest in the foreign aid supply behaviour of bilateral donors. Using the latest data covering the period 1960-2009, this paper examines how such behaviour is related to domestic factors. Based on a simple empirical model, a distinction is made between ...... substantial heterogeneity between countries. There is also good evidence that donor behaviour continues to evolve over time. As such, past trends in aid supplies are unlikely to provide a good guide to those of the future.......The recent financial crisis has rekindled interest in the foreign aid supply behaviour of bilateral donors. Using the latest data covering the period 1960-2009, this paper examines how such behaviour is related to domestic factors. Based on a simple empirical model, a distinction is made between...... long-run supply trends and short-run dynamics, which motivates use of error correction methods. Panel econometric techniques are employed that are consistent in the presence of parameter heterogeneity and cross-section dependence. Results support the error correction framework, but point to very...

  7. Redirecting British foreign aid.

    Science.gov (United States)

    Dean, M

    1994-01-01

    Britain has longed followed a disease-control strategy for providing aid in the health sector to developing, low-income countries. Given, however, the high level of waste upon tertiary care and specialized medicine in current health programs of low-income countries as documented by the World Bank; the poor performance of existing general government hospitals and clinics; and the poor image of Third World health systems in the eyes of Western officials and government ministers, the chief health advisor of the Overseas Development Administration has called for a drastic redirection of policy toward development aid. Specifically, a shift away from a specific-disease control approach toward an overall, sweeping reform of the health sector in developing countries is urged. The level of waste needs to be reduced and more attention given to the poor. Unless such changes result, government ministers will grow increasingly reluctant to provide tangible aid to the health sectors of countries in need. The availability of such funds invested in effective, well-managed health programs will grow more critical to health in the Third World as populations shift away from communicable disease morbidity and mortality toward illnesses which are of a more noncommunicable nature such as stroke and cancer.

  8. Simple synthesis of mesoporous FeNi/graphitic carbon nanocomposite catalysts and study on their activities in catalytic cracking of toluene

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Yangang, E-mail: ygwang8136@gmail.com [Department of Environmental Science and Engineering, University of Shanghai for Science and Technology, Shanghai 200093 (China); Chen, Yuting; Yao, Mingcui [Department of Environmental Science and Engineering, University of Shanghai for Science and Technology, Shanghai 200093 (China); Qin, Hengfei; Kang, Shifei; Li, Xi [Department of Environmental Science and Engineering, Fudan University, Shanghai 200433 (China); Zuo, Yuanhui; Zhang, Xiaodong [Department of Environmental Science and Engineering, University of Shanghai for Science and Technology, Shanghai 200093 (China); Cui, Li-Feng, E-mail: lifeng.cui@gmail.com [Department of Environmental Science and Engineering, University of Shanghai for Science and Technology, Shanghai 200093 (China)

    2015-11-01

    Mesoporous FeNi alloy/graphitic carbon nanocomposite catalysts with different Fe/Ni molar ratios have been synthesized through a simple solid–liquid grinding/templating method using mesoporous silica SBA-15 as the template. Metal nitrates and natural soybean oil were respectively used as the magnetic particle precursors and carbon source, which can be infiltrated into the silica template after simple impregnation, grinding and subsequent heat treatment. X-ray diffraction, nitrogen adsorption–desorption, transmission electron microscopy and thermogravimetric analysis techniques were used to characterize the samples. It is observed that high contents of FeNi alloy nanoparticles with the sizes of 3–6 nm are well dispersed into the walls of graphitic mesoporous carbon matrix, and the resulting nanocomposites have a uniform mesostructure with a high specific surface area and large pore volume. Because of these properties, the obtained FeNi/graphitic carbon nanocomposites can be used as novel catalysts for the catalytic cracking of toluene and exhibit a higher activity and stability than FeNi/commercial activated carbon (AC) catalyst. After a period of 810 min reaction at 700 °C, the toluene conversion on the FeNi/graphitic carbon nanocomposites can be maintained at a level of more than 75% and this value is 2.5 times as high as that of the FeNi/AC catalyst. - Highlights: • Mesoporous FeNi alloy/graphitic carbon nanocomposites (FeNi/GCN) were synthesized. • High contents of FeNi alloy nanoparticles are well embedded into the graphitic carbon walls. • The obtained FeNi/GCN catalysts have a high surface area and uniform mesostructure. • The FeNi/GCN catalysts exhibited excellent catalytic performance in the cracking of toluene.

  9. Direct decomposition of methane over SBA-15 supported Ni, Co and Fe based bimetallic catalysts

    Energy Technology Data Exchange (ETDEWEB)

    Pudukudy, Manoj, E-mail: manojpudukudy@gmail.com [Fuel Cell Institute, Universiti Kebangsaan Malaysia, UKM, Bangi 43600, Selangor (Malaysia); Department of Chemical and Process Engineering, Faculty of Engineering and Built Environment, Universiti Kebangsaan Malaysia, UKM, Bangi 43600, Selangor (Malaysia); Yaakob, Zahira, E-mail: zahirayaakob65@gmail.com [Department of Chemical and Process Engineering, Faculty of Engineering and Built Environment, Universiti Kebangsaan Malaysia, UKM, Bangi 43600, Selangor (Malaysia); Akmal, Zubair Shamsul [Department of Chemical and Process Engineering, Faculty of Engineering and Built Environment, Universiti Kebangsaan Malaysia, UKM, Bangi 43600, Selangor (Malaysia)

    2015-03-01

    Graphical abstract: - Highlights: • Synthesis and characterization of Ni, Co and Fe based bimetallic catalysts supported over SBA-15. • Thermocatalytic decomposition of methane over the SBA-15 supported bimetallic catalysts. • Enhanced catalytic efficiency of the bimetallic catalysts for the production of CO{sub x} free hydrogen and nanocarbon. • Production of value added open tip hollow multi-walled carbon nanotubes. • Crystalline characterization of carbon nanotubes by XRD, Raman and thermogravimetric analysis. - Abstract: Thermocatalytic decomposition of methane is an alternative route for the production of CO{sub x}-free hydrogen and carbon nanomaterials. In this work, a set of novel Ni, Co and Fe based bimetallic catalysts supported over mesoporous SBA-15 was synthesized by a facile wet impregnation route, characterized for their structural, textural and reduction properties and were successfully used for the methane decomposition. The fine dispersion of metal oxide particles on the surface of SBA-15, without affecting its mesoporous texture was clearly shown in the low angle X-ray diffraction patterns and the transmission electron microscopy (TEM) images. The nitrogen sorption analysis showed the reduced specific surface area and pore volume of SBA-15, after metal loading due to the partial filling of hexagonal mesopores by metal species. The results of methane decomposition experiments indicated that all of the bimetallic catalysts were highly active and stable for the reaction at 700 °C even after 300 min of time on stream (TOS). However, a maximum hydrogen yield of ∼56% was observed for the NiCo/SBA-15 catalyst within 30 min of TOS. A high catalytic stability was shown by the CoFe/SBA-15 catalyst with 51% of hydrogen yield during the course of reaction. The catalytic stability of the bimetallic catalysts was attributed to the formation of bimetallic alloys. Moreover, the deposited carbons were found to be in the form of a new set of hollow

  10. Automotive Catalyst State Diagnosis Using Microwaves

    Directory of Open Access Journals (Sweden)

    Moos Ralf

    2015-01-01

    Full Text Available The state of catalysts plays a key role in automotive exhaust gas aftertreatment. The soot or ash loading of Diesel particulate filters, the oxygen loading degree in three-way catalysts, the amount of stored ammonia in SCR catalysts, or the NOx loading degree in NOx storage catalysts are important parameters that are today determined indirectly and in a model-based manner with gas sensors installed upstream and/or downstream of the catalysts. This contribution gives an overview on a novel approach to determine the catalyst state directly by a microwave-based technique. The method exploits the fact that the catalyst housing acts as a microwave cavity resonator. As “sensing” elements, one or two simple antennas are mounted inside the catalyst canning. The electrical properties of the catalyst device (ceramic honeycomb plus coating and storage material can be measured. Preferably, the resonance characteristics, e.g., the resonance frequencies, of selected cavity modes are observed. The information on the catalyst interior obtained in such a contactless manner is very well correlated with the catalyst state as will be demonstrated for different exhaust gas aftertreatment systems.

  11. Autothermal reforming catalyst having perovskite structure

    Science.gov (United States)

    Krumpel, Michael; Liu, Di-Jia

    2009-03-24

    The invention addressed two critical issues in fuel processing for fuel cell application, i.e. catalyst cost and operating stability. The existing state-of-the-art fuel reforming catalyst uses Rh and platinum supported over refractory oxide which add significant cost to the fuel cell system. Supported metals agglomerate under elevated temperature during reforming and decrease the catalyst activity. The catalyst is a perovskite oxide or a Ruddlesden-Popper type oxide containing rare-earth elements, catalytically active firs row transition metal elements, and stabilizing elements, such that the catalyst is a single phase in high temperature oxidizing conditions and maintains a primarily perovskite or Ruddlesden-Popper structure under high temperature reducing conditions. The catalyst can also contain alkaline earth dopants, which enhance the catalytic activity of the catalyst, but do not compromise the stability of the perovskite structure.

  12. Cationic ruthenium alkylidene catalysts bearing phosphine ligands.

    Science.gov (United States)

    Endo, Koji; Grubbs, Robert H

    2016-02-28

    The discovery of highly active catalysts and the success of ionic liquid immobilized systems have accelerated attention to a new class of cationic metathesis catalysts. We herein report the facile syntheses of cationic ruthenium catalysts bearing bulky phosphine ligands. Simple ligand exchange using silver(i) salts of non-coordinating or weakly coordinating anions provided either PPh3 or chelating Ph2P(CH2)nPPh2 (n = 2 or 3) ligated cationic catalysts. The structures of these newly reported catalysts feature unique geometries caused by ligation of the bulky phosphine ligands. Their activities and selectivities in standard metathesis reactions were also investigated. These cationic ruthenium alkylidene catalysts reported here showed moderate activity and very similar stereoselectivity when compared to the second generation ruthenium dichloride catalyst in ring-closing metathesis, cross metathesis, and ring-opening metathesis polymerization assays.

  13. Strength of Hard Alloys,

    Science.gov (United States)

    Partial replacement of titanium carbide by tantalum carbide in three-phase WC-TiC-Co alloys tends to have a favorable effect on mechanical properties such as fatigue strength under bending and impact durability.

  14. Alloy Selection System

    Energy Technology Data Exchange (ETDEWEB)

    None

    2001-02-01

    Software will Predict Corrosion Rates to Improve Productivity in the Chemical Industry. Many aspects of equipment design and operation are influenced by the choice of the alloys used to fabricate process equipment.

  15. First Everlasting Alloy

    Institute of Scientific and Technical Information of China (English)

    杨仲言

    1994-01-01

    There′s new alloy that apparently just won′t give up. When a pin was scraped along it the equivalent of one million times, the alloy-made of zirconium, palladium, and ruthenium—displayed no net loss of surface material. When astonished researchers at the National Institute of Standards and Technology(NIST) persevered with a five-million-cycle wear test, they got the same result.

  16. Machining of titanium alloys

    CERN Document Server

    2014-01-01

    This book presents a collection of examples illustrating the resent research advances in the machining of titanium alloys. These materials have excellent strength and fracture toughness as well as low density and good corrosion resistance; however, machinability is still poor due to their low thermal conductivity and high chemical reactivity with cutting tool materials. This book presents solutions to enhance machinability in titanium-based alloys and serves as a useful reference to professionals and researchers in aerospace, automotive and biomedical fields.

  17. Formation of Pt-Zn Alloy Nanoparticles by Electron-Beam Irradiation of Wurtzite ZnO in the TEM

    Science.gov (United States)

    Lee, Sung Bo; Park, Jucheol; van Aken, Peter A.

    2016-07-01

    As is well documented, platinum nanoparticles, promising for catalysts for fuel cells, exhibit better catalytic activities, when alloyed with Zn. Pre-existing syntheses of Pt-Zn alloy catalysts are composed of a number of complex steps. In this study, we have demonstrated that nanoparticles of Pt-Zn alloys are simply generated by electron-beam irradiation in a transmission electron microscope of a wurtzite ZnO single-crystal specimen. The initial ZnO specimen is considered to have been contaminated by Pt during specimen preparation by focused ion beam milling. The formation of the nanoparticle is explained within the framework of ionization damage (radiolysis) by electron-beam irradiation and accompanying electrostatic charging.

  18. Controllable Catalysis with Nanoparticles: Bimetallic Alloy Systems and Surface Adsorbates

    KAUST Repository

    Chen, Tianyou

    2016-05-16

    Transition metal nanoparticles are privileged materials in catalysis due to their high specific surface areas and abundance of active catalytic sites. While many of these catalysts are quite useful, we are only beginning to understand the underlying catalytic mechanisms. Opening the “black box” of nanoparticle catalysis is essential to achieve the ultimate goal of catalysis by design. In this Perspective we highlight recent work addressing the topic of controlled catalysis with bimetallic alloy and “designer” adsorbate-stabilized metal nanoparticles.

  19. Kinetic Monte Carlo simulation of surface segregation in Pd–Cu alloys

    Energy Technology Data Exchange (ETDEWEB)

    Cheng, Feng [Institute of Theoretical and Computational Chemistry, School of Chemistry and Chemical Engineering, Key Laboratory of Mesoscopic Chemistry of MOE, Nanjing University (China); He, Xiang [Nanjing Institute of Geography and Limnology, Chinese Academy of Sciences, Nanjing 210008 (China); Chen, Zhao-Xu, E-mail: zxchen@nju.edu.cn [Institute of Theoretical and Computational Chemistry, School of Chemistry and Chemical Engineering, Key Laboratory of Mesoscopic Chemistry of MOE, Nanjing University (China); Huang, Yu-Gai [Institute of Theoretical and Computational Chemistry, School of Chemistry and Chemical Engineering, Key Laboratory of Mesoscopic Chemistry of MOE, Nanjing University (China); JiangSu Second Normal University, Nanjing (China)

    2015-11-05

    The knowledge of surface composition and atomic arrangement is prerequisite for understanding of catalytic properties of an alloy catalyst. Gaining such knowledge is rather difficult, especially for those possessing surface segregation. Pd–Cu alloy is used in many fields and possesses surface segregation. In this paper kinetic Monte Carlo method is used to explore the surface composition and structure and to examine the effects of bulk composition and temperature on the surface segregation of Pd–Cu alloys. It is shown that the segregation basically completes within 900 s at 500 K. Below 900 K and within 20 min the enriched surface Cu atoms mainly come from the top five layers. For the first time we demonstrate that there exists a “bulk-inside flocking” or clustering phenomenon (the same component element congregates in bulk) in Pd–Cu alloys. Our results indicate that for alloys with higher Cu content there are small Pd ensembles like monomers, dimers and trimers with contiguous subsurface Pd atoms. - Highlights: • Kinetic Monte Carlo was first used to study surface segregation of Pd–Cu alloys. • Bulk-inside flocking (the same component element congregates in bulk) was observed. • Small Pd ensembles with contiguous subsurface Pd exist on surfaces of Cu-rich alloys.

  20. Investigation of nano Pt and Pt-based alloys electrocatalysts for direct methanol fuel cells and their properties

    Directory of Open Access Journals (Sweden)

    Chunguang Suo

    2014-03-01

    Full Text Available The electrocatalysts used in micro direct methanol fuel cell (μDMFC, such as Pt/C and Pt alloy/C, prepared by liquid-phase NaBH4 reduction method have been investigated. XC-72 (Cobalt corp. Company, U.S.A is chosen as the activated carrier for the electrocatalysts to keep the catalysts powder in the range of several nanometers. The XRD, SEM, EDX analyses indicated that the catalysts had small particle size in several nanometers, in excellent dispersed phase and the molar ratio of the precious metals was found to be optimal. The performances of the DMFCs using cathodic catalyst with Pt percentage of 30wt% and different anodic catalysts (Pt-Ru, Pt-Ru-Mo were tested. The polarization curves and power density curves of the cells were measured to determine the optimal alloy composition and condition for the electrocatalysts. The results showed that the micro direct methanol fuel cell with 30wt% Pt/C as the cathodic catalyst and n(Pt:n(Ru:n(Mo = 3:2:2 PtRuMo/C as the anodic catalyst at room temperature using 2.0mol/L methanol solution has the best performances.

  1. Sodium citrate assisted facile synthesis of AuPd alloy networks for ethanol electrooxidation with high activity and durability

    Science.gov (United States)

    Zhai, Yanling; Zhu, Zhijun; Lu, Xiaolin; Zhou, H. Susan

    2016-10-01

    The direct ethanol fuel cell is an emerging energy conversion device for which palladium is considered as the one of the most effective components for anode catalyst, however, its widespread application has been still limited by the activity and durability of the anode catalyst. In this work, AuPd alloy networks (NWs) are synthesized using H2PdCl4 and HAuCl4 as precursors reduced by NaBH4 in the presence of sodium citrate (SC). The results reveal that SC plays significant role in network structure, resulting in the enhanced electrocatalytic activity of the catalyst. This self-supported AuPd NWs catalyst exhibits much higher electrochemical catalytic activity than commercial Pd/C catalyst toward ethanol electrooxidation in alkaline solution. Significantly, AuPd NWs catalyst shows extremely high durability at the beginning of the chronoamperometry test, and as high as 49% of the mass current density (1.41 A/mgPd) remains after 4000 s current-time test at -0.3 V (vs. Ag/AgCl) in N2-saturated KOH-ethanol solution. This strategy provides a facile method for the preparation of alloy networks with high electrochemical activity, and can be potentially expanded to a variety of electrochemical applications.

  2. Nanoporosity formation in silver-gold alloys

    Science.gov (United States)

    Dursun, Aziz

    Selective dissolution also known as dealloying is a corrosion process in which one component of a binary alloy system is selectively removed through an electrochemically controlled process which leads to the formation of a porous metal "sponge" with a porosity that is completely interconnected and random in direction. Nanoporous metals are desirable since they have larger surface areas than an equal volume of non-porous material. Because of their enormous surface area per volume, these highly porous metal electrodes are superior materials for high surface area applications such as in biomedical devices, microfilters and catalysts. Understanding the kinetic processes governing the development of porosity during dealloying and having ability to change the electrochemical conditions will allow us to better control over the average ligament size and distribution in porosity. The basic kinetic processes involved in the formation of these structures are related to such issues as environmental effects and electrochemical conditions on diffusion, microscopic coarsening phenomenon at room temperature and elevated temperatures, alloy passivation, and Gibbs-Thomson effects. The average pore size and distribution was found to depend on the electrolyte composition, dealloying rate, applied potential and time. The porosity was found to significantly coarsen at room temperature during the dealloying process and this coarsening was highly dependent on the applied potential. It is showed that the commonly accepted measurement of the critical potential for alloy dissolution calculated based on extrapolation of anodic polarization data results in an overestimation of this quantity. A series of constant applied potential experiments prove to be a more accurate method for critical potential determination.

  3. Biodiesel production using heterogeneous catalysts.

    Science.gov (United States)

    Semwal, Surbhi; Arora, Ajay K; Badoni, Rajendra P; Tuli, Deepak K

    2011-02-01

    The production and use of biodiesel has seen a quantum jump in the recent past due to benefits associated with its ability to mitigate greenhouse gas (GHG). There are large number of commercial plants producing biodiesel by transesterification of vegetable oils and fats based on base catalyzed (caustic) homogeneous transesterification of oils. However, homogeneous process needs steps of glycerol separation, washings, very stringent and extremely low limits of Na, K, glycerides and moisture limits in biodiesel. Heterogeneous catalyzed production of biodiesel has emerged as a preferred route as it is environmentally benign needs no water washing and product separation is much easier. The present report is review of the progress made in development of heterogeneous catalysts suitable for biodiesel production. This review shall help in selection of suitable catalysts and the optimum conditions for biodiesel production.

  4. Microstructures of erbium modified aluminum-copper alloys

    Energy Technology Data Exchange (ETDEWEB)

    Berghof-Hasselbaecher, Ellen; Schmidt, Gerald; Galetz, Mathias; Schuetze, Michael [DECHEMA-Forschungsinstitut, Frankfurt am Main (Germany); Masset, Patrick J. [Fraunhofer UMSICHT-ATZ Entwicklungszentrum, Sulzbach-Rosenberg (Germany); Zhang, Ligang [Technische Univ. Bergakademie Freiberg (Germany). ZIK Virtuhcon; Liu, Libin; Jin, Zhanpeng [Central South Univ., Changsha, Hunan (China)

    2012-07-01

    Alloying with rare earth metals improves to the mechanical properties and corrosion resistance of aluminium base alloys at high temperatures. The rare earth metal erbium may be used for grain refinement. Within a project of computer-aided alloy development based on the CALPHAD (CALculation of PHAse Diagrams) method various alloys were melted on the Al-rich side of the ternary system Al-Cu-Er under argon atmosphere and their microstructures were characterized in the as-cast state or after long-term isothermal annealing (400 C/960 h) by means of different investigation techniques. As a result, the phases fcc (Al), {tau}{sub 1}-Al{sub 8}Cu{sub 4}Er, {theta}-CuAl{sub 2}, {eta}-CuAl, and Al{sub 3}Er were identified, their compositions and fractions were quantified, and their hardnesses were determined. The experimental obtained microstructures agree very well with the calculated solidification behaviors of the cast alloys. The knowledge gained from this work about the phase compositions and microstructures can also be utilized for the fine optimization of the phase diagram. (orig.)

  5. Alternative alkali resistant deNOx catalysts

    DEFF Research Database (Denmark)

    Putluru, Siva Sankar Reddy; Kristensen, Steffen Buus; Due-Hansen, Johannes;

    2012-01-01

    Alternative alkali resistant deNOx catalysts were prepared using three different supports ZrO2, TiO2 and Mordenite zeolite. The majority of the catalysts were prepared by incipient wetness impregnation of a commercial support, with vanadium, copper or iron precursor, one catalyst was prepared...... by onepot sol–gel method. All catalysts were characterized by BET, XRPD and NH3-TPD. Initial SCR activities of 8 out of 9 catalysts showed higher NO conversion at least at one temperature in the temperature range 300–500 ◦C compared to the conventional V2O5-WO3/TiO2 catalyst. After potassium poisoning (100......–130 µmol of K/g of catalyst) the relative drop in SCR activity and acidity was lower for all the alternative catalysts compared to the industrial V2O5-WO3/TiO2 catalyst. Furthermore, Cu/MOR and Nano-V2O5/Sul-TiO2 catalysts showed 8–16 times higher SCR activities than the conventional even after high...

  6. [Adolescence and AIDS].

    Science.gov (United States)

    1991-01-01

    The myths and prejudices that distort the reality and hide the true causes and effects of natural and social phenomena related to sexuality have a fertile ground in AIDS, given its obvious link to sex. The alarming spread of AIDS has been 1 result of these myths and prejudices. Human beings are sexual by nature; genital organs determine sex and also induce sexual behavior. It is by not fairly well accepted that an individual's sexuality exists from birth. Puberty usually begins at 12-16 years for both sexes. The physical changes of puberty terminate in the ability of the female to conceive and the male to procreate. The sexual excitation of adolescents resulting from production of various hormones can only be eliminated by some type of sexual satisfaction or sublimation. Sexuality, according to Freud, is an organizing principle of the personality. The sexual organs exist not merely for reproduction but to provide pleasure. Puberty signifies entry into active sex life. But the ideological structure of society, perpetuated by the family, schools, religion, the mass media, and other social institutions, sends confused signals to adolescents, requiring abstinence and virginity until marriage for women while encouraging sexual adventures for men. Adolescents are confronted by their new sexual feelings in the midst of a virtual bombardment of visual sexual stimuli from the mass media. It becomes impossible for adolescents to satisfy the requirements of appearances while also resolving the problems and pressures of their newly gained sexual maturity. Many adolescents become sexually active, and the problem is not to prevent sexual activity but to improve the conditions under which it occurs. Adolescents, lacking education and information about sex, begin their sex lives without protection. AIDS has now been added to the list of dire consequences that can result. A true sex education beginning in the home is needed to enable young people to develop healthy and full sex

  7. Hearing aid adjustment

    DEFF Research Database (Denmark)

    Heinemann, Trine; Matthews, Ben; Raudaskoski, Pirkko Liisa

    2012-01-01

    to the interaction during hearing aid fitting. This report of a Danish pilot study describes two such problems. The first problem arises from the requirement that the audiologist needs to ‘translate’ the patient’s subjective hearing description for making technological decisions. The second problem is the way......Conversation analytic research on clinical encounters shows that interactional conduct can be consequential for diagnosis, treatment and compliance. Problems reported for doctor-patient interaction can also be identified in Danish audiological encounters. There are, however, also specific aspects...

  8. First aid in mathematics

    CERN Document Server

    Sulley, Robert

    2014-01-01

    Achieve the best possible standard with this bestselling book of traditional practice and guidance - now in colour!. First Aid in Mathematics provides all the help and support needed for learning and practising Mathematics. It offers comprehensive coverage of core mathematical topics in clear and accessible language. It is suitable for both native English speakers and students of English as a second language and can be used in class, or as a reference and revision book. - Develops a strong basis of understanding with core topics covered in clear and accessible language. - Improves student's ab

  9. Ultrasound-assisted Cinnamaldehyde Hydrogenation to Cinnamyl Alcohol at Atmospheric Pressure over Ru-B Amorphous Catalyst

    Institute of Scientific and Technical Information of China (English)

    LI Hui; MA Chun-Jing; LI He-Xing

    2006-01-01

    The ultrafine Ru-B amorphous alloy catalyst was prepared by chemical reduction with KBH4. During liquid phase hydrogenation of cinnamaldehyde at atmospheric pressure, the Ru-B catalyst prepared exhibited excellent selectivity to cinnamyl alcohol. When the hydrogenation was performed with ultrasonic irradiation, the reaction rate could be greatly enhanced while the selectivity to cinnamyl alcohol remained almost unchanged. The hydrogenation rate was increased with the increase of either the ultrasonic frequency or the irradiation time. According to various characterizations, such as XRD, XPS, TEM, BET and ICP, the effect of ultrasonic irradiation on the structural and electronic characteristics of Ru-B catalyst was studied briefly. Meanwhile, the promotion effect of ultrasonication on the catalytic performance was also discussed based on the selective hydrogenation of cinnamaldehyde to cinnamyl alcohol.

  10. An anodic alumina supported Ni-Pt bimetallic plate-type catalysts for multi-reforming of methane, kerosene and ethanol

    KAUST Repository

    Zhou, Lu

    2014-05-01

    An anodic alumina supported Ni-Pt bimetallic plate-type catalyst was prepared by a two-step impregnation method. The trace amount 0.08 wt% of Pt doping efficiently suppressed the nickel particle sintering and improved the nickel oxides reducibility. The prepared Ni-Pt catalyst showed excellent performance during steam reforming of methane, kerosene and ethanol under both 3000 h stationary and 500-time daily start-up and shut-down operation modes. Self-activation ability of this catalyst was evidenced, which was considered to be resulted from the hydrogen spillover effect over Ni-Pt alloy. In addition, an integrated combustion-reforming reactor was proposed in this study. However, the sintering of the alumina support is still a critical issue for the industrialization of Ni-Pt catalyst. Copyright © 2014, Hydrogen Energy Publications, LLC. Published by Elsevier Ltd. All rights reserved.

  11. Aid Policy and the Macroeconomic Management of Aid

    DEFF Research Database (Denmark)

    Addison, Tony; Tarp, Finn

    2015-01-01

    This is an introduction to the UNU-WIDER special issue of World Development on aid policy and the macroeconomic management of aid. We provide an overview of the 10 studies, grouping them under three sub-themes: the aid–growth relationship; the supply-side of aid (including its level, volatility......, and coordination of donors); and the macroeconomic framework around aid. The studies in the special issue demonstrate the centrality of research methodology, the importance of disaggregation, and the need to account for country-specific situations and problems. This introduction concludes that the sometimes “over...

  12. Recent results for bonding S-65C grade Be to copper alloys

    Energy Technology Data Exchange (ETDEWEB)

    Dombrowski, D.W. [Brush Wellman Inc., Cleveland, OH (United States)

    1995-09-01

    Novel processes for bonding beryllium to copper alloys without the use of a silver bonding aid have been developed at Brush Wellman. Tensile strength results will be presented at room temperature and elevated temperatures. A comparison will be made between bond strengths derived from rectangular tensile specimens and reduced section tensile specimens. Failure modes of the specimens at various temperatures will be shown.

  13. RBF-Type Artificial Neural Network Model Applied in Alloy Design of Steels

    Institute of Scientific and Technical Information of China (English)

    YOU Wei; LIU Ya-xiu; BAI Bing-zhe; FANG Hong-sheng

    2008-01-01

    RBF model, a new type of artificial neural network model was developed to design the content of carbon in low-alloy engineering steels. The errors of the ANN model are. MSE 0. 052 1, MSRE 17. 85%, and VOF 1. 932 9. The results obtained are satisfactory. The method is a powerful aid for designing new steels.

  14. Talking about AIDS

    Directory of Open Access Journals (Sweden)

    2003-09-01

    Full Text Available This paper explores the significance of social relationships to two important stages in the process of sexual behavioral change in response to increased HIV/AIDS risk in rural Africa: the perceived risk of becoming HIV-infected through unprotected sexual intercourse and the preferred methods of protection either through sexual fidelity, or through condom use. The empirical analyses are based on cross-sectional data from the 'Kenyan Diffusion and Ideational Change Project' (KDICP which provides information about AIDS-related, ego-centered communication networks of Kenyan men and women. The results show that perceived risks, as well as preferred methods of protection against HIV-infection, depend in general on the prevailing perceptions and favored protective methods within personal communication networks. However, different influential network properties can be found. The risk-perceptions of women are shaped by strong relationships and cohesive network structures. Male's risk perception depends more on the number of risk-perceivers in their communication networks. Heterogeneous relationships of various kinds are influential on women's and men's probability of favoring sexual faithfulness as a method of protection against HIV-infection.

  15. INVESTIGATION OF MAGNESIUM ALLOYS MACHINABILITY

    Directory of Open Access Journals (Sweden)

    Berat Barıs BULDUM

    2013-01-01

    Full Text Available Magnesium is the lightest structural metal. Magnesium alloys have a hexagonal lattice structure, which affects the fundamental properties of these alloys. Plastic deformation of the hexagonal lattice is more complicated than in cubic latticed metals like aluminum, copper and steel. Magnesium alloy developments have traditionally been driven by industry requirements for lightweight materials to operate under increasingly demanding conditions. Magnesium alloys have always been attractive to designers due to their low density, only two thirds that of aluminium and its alloys [1]. The element and its alloys take a big part of modern industry needs. Especially nowadays magnesium alloys are used in automotive and mechanical (trains and wagons manufacture, because of its lightness and other features. Magnesium and magnesium alloys are the easiest of all metals to machine, allowing machining operations at extremely high speed. All standard machining operations such as turning, drilling, milling, are commonly performed on magnesium parts.

  16. Controlled surface segregation leads to efficient coke-resistant nickel/platinum bimetallic catalysts for the dry reforming of methane

    KAUST Repository

    Li, Lidong

    2015-02-03

    Surface composition and structure are of vital importance for heterogeneous catalysts, especially for bimetallic catalysts, which often vary as a function of reaction conditions (known as surface segregation). The preparation of bimetallic catalysts with controlled metal surface composition and structure is very challenging. In this study, we synthesize a series of Ni/Pt bimetallic catalysts with controlled metal surface composition and structure using a method derived from surface organometallic chemistry. The evolution of the surface composition and structure of the obtained bimetallic catalysts under simulated reaction conditions is investigated by various techniques, which include CO-probe IR spectroscopy, high-angle annular dark-field scanning transmission electron microscopy, energy-dispersive X-ray spectroscopy, extended X-ray absorption fine structure analysis, X-ray absorption near-edge structure analysis, XRD, and X-ray photoelectron spectroscopy. It is demonstrated that the structure of the bimetallic catalyst is evolved from Pt monolayer island-modified Ni nanoparticles to core-shell bimetallic nanoparticles composed of a Ni-rich core and a Ni/Pt alloy shell upon thermal treatment. These catalysts are active for the dry reforming of methane, and their catalytic activities, stabilities, and carbon formation vary with their surface composition and structure. The reform of reforming: A series of alumina-supported Ni/Pt bimetallic nanoparticles (NPs) with controlled surface composition and structure are prepared. Remarkable surface segregation for these bimetallic NPs is observed upon thermal treatment. These bimetallic NPs are active catalysts for CO2 reforming of CH4, and their catalytic activities, stabilities, and carbon formation vary with their surface composition and structure.

  17. Catalysts for decomposing ozone tail gas

    Institute of Scientific and Technical Information of China (English)

    LIU Chang-an; SUN De-zhi; WANG Hui; LI Wei

    2003-01-01

    The preparation of immobilizing-catalysts for decomposing ozone by using dipping method was studied. XRD, XPS and TEM were used to characterize the catalysts. The three kinds of catalysts were selected preferentially, and their catalytic activities were investigated. The results showed that the catalyst with activated carbon dipping acetate (active components are Mn: Cu = 3:2, active component proportion in catalyst is 15%, calcination temperature is 200℃ ) has the best catalytic activity for ozone decomposing. One gram of catalyst can decompose 17.6 g ozone at initial ozone concentration of 2.5 g/m3 and the residence time in reactor of 0.1 s. The experimental results also indicated that humidity of reaction system had negative effect on catalytic activity.

  18. Organic synthesis with olefin metathesis catalysts

    Energy Technology Data Exchange (ETDEWEB)

    Grubbs, R.H. [California Institute of Technology, Pasadena, CA (United States)

    1995-12-31

    Over the past nine years, early transition metal catalysts for the ring opening metathesis polymerization of cyclic olefins have been developed. These catalysts are simple organometallic complexes containing metal carbon multiple bonds that in most cases polymerize olefins by a living process. These catalysts have been used to prepare a family of near monodispersed and structurally homogeneous polymers. A series of group VII ROMP catalysts that allow a wide range of functionality to be incorporated into the polymer side chains have been prepared. The most important member of this family of complexes are the bisphosphinedihalo-ruthenium carbene complexes. These polymerization catalysts can also be used in the synthesis of fine chemicals by ring closing (RCM) and vinyl coupling reactions. The availability of the group VII catalysts allow metathesis to be carried out on highly functionalized substrates such as polypeptides and in unusual environments such as in aqueous emulsions.

  19. EFFECTS OF CATALYST MORPHOLOGY ON HYDROTREATING REACTIONS

    Directory of Open Access Journals (Sweden)

    TYE CHING THIAN

    2008-08-01

    Full Text Available Due to the new environmental regulations for fuel quality, refineries need to process cleaner fuel. This requires an improvement in performance of hydrotreating catalysts. Improvements in catalyst activity require knowledge of the relationships between catalyst morphology and activity. Molybdenum sulfide, the generally agreed catalysts that give the best performance in hydrocracking and hydrotreating was investigated for its morphology effects on hydrotreating reactions. Three types of MoS2 catalysts with different morphology were studied. They are crystalline MoS2, exfoliated MoS2 and MoS2 derived from a precursor, molybdenum naphthenate. Exfoliated MoS2 with minimal long range order, with much higher rim edges has shown relative higher hydrogenation activity. Generally, results of MoS2 catalyst activities in hydrogenation, hydrodesulfurization, hydrodenitrogenation and hydrideoxy¬gena¬tion are in agreement with the rim-edge model.

  20. Investigation of altenative carbon materials for fuel-cell catalyst support

    DEFF Research Database (Denmark)

    Larsen, Mikkel Juul

    In order to ensure high utilization of the catalyst material in a polymer electrolyte membrane fuel cell (PEMFC) it is usually fixed in the form of nanoparticles on a supporting material. The catalyst is platinum or a platinum alloy, and the commonly used support is carbon black (CB). Although...... the large surface area and good anchoring properties make it a suited material for this purpose, it is prone to degradation in the fuel-cell environment. Thus alternative materials with higher durability than CB, but with similar (or better) capability of dispersion, are desired. Among them are highly...... of non- or low-temperature-treated CBs were dominated by defects, and the FWCNTs contained both elements. By XPS it was possible to determine the concentration of oxygen in the carbons, but an exact deconvolution of the XPS peaks was not possible due to the very low oxygen contents, the lack of parameter...

  1. Preparation and Electrocatalytic Characteristics of PdW/C Catalyst for Ethanol Oxidation

    Directory of Open Access Journals (Sweden)

    Qi Liu

    2015-06-01

    Full Text Available A series of PdW alloy supported on Vulcan XC-72 Carbon (PdW/C with total 20 wt. % as electrocatalyst are prepared for ethanol oxidation by an ethylene glycol assisted method. Transmission electron microscopy (TEM characterization shows that PdW nanoparticles with an average size of 3.6 nm are well dispersed on the surface of Vulcan XC-72 Carbon. It is found that the catalytic activity and stability of the PdW/C catalysts are strongly dependent on Pd/W ratios, an optimal Pd/W composition at 1/1 ratio revealed the highest catalytic activity toward ethanol oxidation, which is much better than commercial Pd/C catalysts.

  2. Selective dissolution in binary alloys

    Science.gov (United States)

    McCall, Carol Rene

    Corrosion is an important issue in the design of engineering alloys. De-alloying is an aspect of alloy corrosion related to the selective dissolution of one or more of the components in an alloy. The work reported herein focuses on the topic of de-alloying specific to single-phase binary noble metal alloy systems. The alloy systems investigated were gold-silver and gold-copper. The onset of a bulk selective dissolution process is typically marked by a critical potential whereby the more reactive component in the alloy begins dissolving from the bulk, leading to the formation of a bi-continuous solid-void morphology. The critical potential was investigated for the entire composition range of gold-silver alloys. The results presented herein include the formulation of an expression for critical potential as a function of both alloy and electrolyte composition. Results of the first investigation of underpotential deposition (UPD) on alloys are also presented herein. These results were implemented as an analytical tool to provide quantitative measurements of the surface evolution of gold during de-alloying. The region below the critical potential was investigated in terms of the compositional evolution of the alloy surface. Below the critical potential, there is a competition between the dissolution of the more reactive alloying constituent (either silver or copper) and surface diffusion of gold that serves to cover dissolution sites and prevent bulk dissolution. By holding the potential at a prescribed value below the critical potential, a time-dependent gold enrichment occurs on the alloy surface leading to passivation. A theoretical model was developed to predict the surface enrichment of gold based on the assumption of layer-by-layer dissolution of the more reactive alloy constituent. The UPD measurements were used to measure the time-dependent surface gold concentration and the results agreed with the predictions of the theoretical model.

  3. Structural thermodynamics of alloys

    CERN Document Server

    Manenc, Jack

    1973-01-01

    Technical progress has for a very long time been directly dependent on progress in metallurgy, which is itself connected with improvements in the technology of alloys. Metals are most frequently used in the form of alloys for several reasons: the quantity of pure metal in its native state in the earth's crust is very limited; pure metals must be extracted from ores which are themselves impure. Finally, the methods of treatment used lead more easily to alloys than to pure metals. The most typical case is that of iron, where a pure ore may be found, but which is the starting point for cast iron or steel, alloys of iron and carbon. In addition, the properties of alloys are in general superior to those of pure metals and modem metallurgy consists of controlling these properties so as to make them conform to the requirements of the design office. Whilst the engineer was formerly compelled to adapt his designs and constructions to the materials available, such as wood, stone, bronze, iron, cast iron and ordinary st...

  4. Effect of Phosphine Doping and the Surface Metal State of Ni on the Catalytic Performance of Ni/Al2O3 Catalyst

    Directory of Open Access Journals (Sweden)

    Xiaoru Li

    2015-04-01

    Full Text Available Ni-based catalysts as replacement for noble metal catalysts are of particular interest in the catalytic conversion of biomass due to their cheap and satisfactory catalytic activity. The Ni/SiO2 catalyst has been studied for the hydrogenolysis of glycerol, and doping with phosphorus (P found to improve the catalytic performance significantly because of the formation of Ni2P alloys. However, in the present work we disclose a different catalytic phenomenon for the P-doped Ni/Al2O3 catalyst. We found that doping with P has a significant effect on the state of the active Ni species, and thus improves the selectivity to 1,2-propanediol (1,2-PDO significantly in the hydrogenolysis of glycerol, although Ni-P alloys were not observed in our catalytic system. The structure and selectivity correlations were determined from the experimental data, combining the results of X-ray diffraction (XRD, X-ray photoelectron spectroscopy (XPS, hydrogen temperature-programmed reduction (H2-TPR and ammonia temperature-programmed desorption (NH3-TPD. The presence of NiO species, formed from P-doped Ni/Al2O3 catalyst, was shown to benefit the formation of 1,2-PDO. This was supported by the results of the Ni/Al2O3 catalyst containing NiO species with incomplete reduction. Furthermore, the role the NiO species played in the reaction and the potential reaction mechanism over the P-doped Ni/Al2O3 catalyst is discussed. The new findings in the present work open a new vision for Ni catalysis and will benefit researchers in designing Ni-based catalysts.

  5. Catalyst and process development for hydrogen preparation from future fuel cell feedstocks. Quarterly report, April 1-June 30, 1980. [Pt/Pd

    Energy Technology Data Exchange (ETDEWEB)

    Yarrington, R M; Feins, I R; Hwang, H S

    1980-07-01

    Phase II of the contract, which involved catalyst preparation and evaluation, was nearly completed this quarter. Phase III, which calls for the design and construction of a fuel processor, was started. During the quarter, four types of tests were run on the small scale catalyst screening unit. The operating line for coke-free operations was found to be approximately between 0.41 to 0.44 O/sub 2//C level. Screening at lower O/sub 2//C levels led to problems with plugging. In other tests, increased severity for screening steam reforming catalysts was obtained by doubling the space velocity. Another series of tests were run to determine the gas composition from the catalytic partial oxidation (CPO) section and to evaluate two CPO catalysts. In the other series of tests, catalysts were aged for about 20 hours using a propane, steam, and air mixture before testing with No. 2 oil for another five hours. This latter test has been used to study Pt/Rh catalysts made with various supports. Differences were readily determined for Pt/Rh supported on alpha alumina and Pt/Rh supported on stabilized alumina. This test method will find continued use in evaluating metal-support interactions. Several samples must be evaluated by this method before aging runs are made in the larger unit. After leaching alumina from a used Pt/Rh catalyst, the x-ray diffraction pattern showed the presence of a Pt-Rh alloy in the metal residue. Experiments were run to show that the alloy was formed in the reactor during testing and not during catalyst preparation. A larger version of the ATR reactor has been designed and major components are on order. Completion of the construction phase is scheduled for the next quarter.

  6. National HIV/AIDS Strategy

    Centers for Disease Control (CDC) Podcasts

    2012-02-01

    Dr. Kevin Fenton, Director of CDC’s National Center for HIV/AIDS, Viral Hepatitis, STD, and TB Prevention, talks about the importance of the National HIV/AIDS Strategy and the work of CDC.  Created: 2/1/2012 by National Center for HIV/AIDS, Viral Hepatitis, STD, and TB Prevention (NCHHSTP).   Date Released: 2/1/2012.

  7. Aid, social policy, and development

    DEFF Research Database (Denmark)

    Addison, Tony; Niño-Zarazúa, Miguel; Tarp, Finn

    This paper discusses past and current social policy strategies in the international aid architecture. From the 1990s, aid strategy and policy shifted to put a stronger emphasis on human development. This accelerated with the Millennium Development Goals and will continue under the Sustainable...... Development Goals, which have even more ambitious targets. The paper also assesses some of the concerns associated with the ‘Paris-style’ aid modalities, and discusses major challenges for the future global development agenda....

  8. Oxidation catalysts on alkaline earth supports

    Energy Technology Data Exchange (ETDEWEB)

    Mohajeri, Nahid

    2017-03-21

    An oxidation catalyst includes a support including particles of an alkaline earth salt, and first particles including a palladium compound on the support. The oxidation catalyst can also include precious metal group (PMG) metal particles in addition to the first particles intermixed together on the support. A gas permeable polymer that provides a continuous phase can completely encapsulate the particles and the support. The oxidation catalyst may be used as a gas sensor, where the first particles are chemochromic particles.

  9. Molecular catalysts structure and functional design

    CERN Document Server

    Gade, Lutz H

    2014-01-01

    Highlighting the key aspects and latest advances in the rapidly developing field of molecular catalysis, this book covers new strategies to investigate reaction mechanisms, the enhancement of the catalysts' selectivity and efficiency, as well as the rational design of well-defined molecular catalysts. The interdisciplinary author team with an excellent reputation within the community discusses experimental and theoretical studies, along with examples of improved catalysts, and their application in organic synthesis, biocatalysis, and supported organometallic catalysis. As a result, readers wil

  10. Methane Tri-reforming over nickel catalysts

    OpenAIRE

    García Vargas, José Manuel

    2014-01-01

    The present work is part of a research program carried out in the Department of Chemical Engineering at the University of Castilla-La Mancha, focused in the preparation, characterization and evaluation of catalysts that can be applied in industrially relevant reactions. In this way, the PhD work reported here was aimed to study and improve nickel catalysts applied to the tri-reforming process, evaluating the role of support, precursor and promoter and optimizing the catalyst preparation. Furt...

  11. Molybdenum chloride catalysts for Z-selective olefin metathesis reactions

    Science.gov (United States)

    Koh, Ming Joo; Nguyen, Thach T.; Lam, Jonathan K.; Torker, Sebastian; Hyvl, Jakub; Schrock, Richard R.; Hoveyda, Amir H.

    2017-01-01

    The development of catalyst-controlled stereoselective olefin metathesis processes has been a pivotal recent advance in chemistry. The incorporation of appropriate ligands within complexes based on molybdenum, tungsten and ruthenium has led to reactivity and selectivity levels that were previously inaccessible. Here we show that molybdenum monoaryloxide chloride complexes furnish higher-energy (Z) isomers of trifluoromethyl-substituted alkenes through cross-metathesis reactions with the commercially available, inexpensive and typically inert Z-1,1,1,4,4,4-hexafluoro-2-butene. Furthermore, otherwise inefficient and non-stereoselective transformations with Z-1,2-dichloroethene and 1,2-dibromoethene can be effected with substantially improved efficiency and Z selectivity. The use of such molybdenum monoaryloxide chloride complexes enables the synthesis of representative biologically active molecules and trifluoromethyl analogues of medicinally relevant compounds. The origins of the activity and selectivity levels observed, which contradict previously proposed principles, are elucidated with the aid of density functional theory calculations.

  12. De-alloyed platinum nanoparticles

    Science.gov (United States)

    Strasser, Peter; Koh, Shirlaine; Mani, Prasanna; Ratndeep, Srivastava

    2011-08-09

    A method of producing de-alloyed nanoparticles. In an embodiment, the method comprises admixing metal precursors, freeze-drying, annealing, and de-alloying the nanoparticles in situ. Further, in an embodiment de-alloyed nanoparticle formed by the method, wherein the nanoparticle further comprises a core-shell arrangement. The nanoparticle is suitable for electrocatalytic processes and devices.

  13. POLYMER-SUPPORTED LEWIS ACID CATALYSTS. VI. POLYSTYRENE-BONDED STANNIC CHLORIDE CATALYST

    Institute of Scientific and Technical Information of China (English)

    RAN Ruicheng; FU Diankui

    1991-01-01

    A polystyrene-bonded stannic chloride catalyst was synthesized by the method of lithium polystyryl combined with stannic chloride. This catalyst is a polymeric organometallic compound containing 0.25 mmol Sn(IV)/g catalyst. The catalyst showed sufficient stability and catalytic activity in organic reaction such as esterification, acetalation and ketal formation, and it could be reused many times without losing its catalytic activity.

  14. National Latino AIDS Awareness Day

    Centers for Disease Control (CDC) Podcasts

    2014-10-08

    This podcast highlights National Latino AIDS Awareness Day, to increase awareness of the disproportionate impact of HIV on the Hispanic or Latino population in the United States and dependent territories. The podcast reminds Hispanics or Latinos that they have the power to take control of their health and protect themselves against HIV.  Created: 10/8/2014 by Office of Health Equity, Office of the Director, Division of HIV/AIDS Prevention, National Center for HIV/AIDS, Viral Hepatitis, STD and TB Prevention, Division of HIV/AIDS Prevention.   Date Released: 10/14/2014.

  15. Public knowledge about AIDS increasing.

    Science.gov (United States)

    Campbell, M J; Waters, W E

    1987-04-04

    In response to concern over the perceived limited effectiveness of Department of Health and Social Security (UK) advertising campaigns to inform the public of the basic facts of Acquired Immunodeficiency Syndrome (AIDS), a prospective questionnaire study was undertaken in Southampton, England to test the effectiveness of government education prior to a January, 1987 government television/leaflet advertising campaign. 300 questionnaires about AIDS were mailed in December of 1986 to a sample drawn from electoral rolls. The response rate was 61%. Most of the questions were drawn from material covered in the campaign. The results seemed to indicate a small overall increase in knowledge about AIDS. Some changes from a June survey were noted, e.g.: more people were aware that AIDS is a virus for which there is no cure and that it is not readily transmitted by sharing washing, eating or drinking utensils; more people believed that the statement that women are at greater risk for catching AIDS is false. Respondents were generally favorable to the government's continued use of television, even with explicit language, and to its use of the schools, for AIDS education. Many were not aware of the dangers to intravenous drug users or of the symptoms of AIDS. Other surveys have shown an increasing knowledge of AIDS dangers. It is possible that television coverage of the problem will continue to be necessary, in order that less literate populations be reached. Further AIDS health education in general is needed.

  16. Tuning the surface electronic structure of a Pt3Ti(111) electro catalyst

    Science.gov (United States)

    Paßens, M.; Caciuc, V.; Atodiresei, N.; Moors, M.; Blügel, S.; Waser, R.; Karthäuser, S.

    2016-07-01

    Increasing the efficiency and stability of bimetallic electro catalysts is particularly important for future clean energy technologies. However, the relationship between the surface termination of these alloys and their catalytic activity is poorly understood. Therefore, we report on fundamental UHV-SPM, LEED, and DFT calculations of the Pt3Ti(111) single crystal surface. Using voltage dependent imaging the surface termination of Pt3Ti(111) was studied with atomic resolution. Combining these images with simulated STM maps based on ab initio DFT calculations allowed us to identify the three upper layers of the Pt3Ti(111) single crystal and their influence upon the surface electronic structure. Our results show that small changes in the composition of the second and third atomic layer are of significant influence upon the surface electronic structure of the Pt3Ti electro catalyst. Furthermore, we provide relevant insights into the dependence of the surface termination on the preparation conditions.Increasing the efficiency and stability of bimetallic electro catalysts is particularly important for future clean energy technologies. However, the relationship between the surface termination of these alloys and their catalytic activity is poorly understood. Therefore, we report on fundamental UHV-SPM, LEED, and DFT calculations of the Pt3Ti(111) single crystal surface. Using voltage dependent imaging the surface termination of Pt3Ti(111) was studied with atomic resolution. Combining these images with simulated STM maps based on ab initio DFT calculations allowed us to identify the three upper layers of the Pt3Ti(111) single crystal and their influence upon the surface electronic structure. Our results show that small changes in the composition of the second and third atomic layer are of significant influence upon the surface electronic structure of the Pt3Ti electro catalyst. Furthermore, we provide relevant insights into the dependence of the surface termination on the

  17. Pt-Ni and Pt-Co Catalyst Synthesis Route for Fuel Cell Applications

    Science.gov (United States)

    Firdosy, Samad A.; Ravi, Vilupanur A.; Valdez, Thomas I.; Kisor, Adam; Narayan, Sri R.

    2013-01-01

    Oxygen reduction reactions (ORRs) at the cathode are the rate-limiting step in fuel cell performance. The ORR is 100 times slower than the corresponding hydrogen oxidation at the anode. Speeding up the reaction at the cathode will improve fuel cell efficiency. The cathode material is generally Pt powder painted onto a substrate (e.g., graphite paper). Recent efforts in the fuel cell area have focused on replacing Pt with Pt-X alloys (where X = Co, Ni, Zr, etc.) in order to (a) reduce cost, and (b) increase ORR rates. One of these strategies is to increase ORR rates by reducing the powder size, which would result in an increase in the surface area, thereby facilitating faster reaction rates. In this work, a process has been developed that creates Pt-Ni or Pt-Co alloys that are finely divided (on the nano scale) and provide equivalent performance at lower Pt loadings. Lower Pt loadings will translate to lower cost. Precursor salts of the metals are dissolved in water and mixed. Next, the salt mixtures are dried on a hot plate. Finally, the dried salt mixture is heattreated in a furnace under flowing reducing gas. The catalyst powder is then used to fabricate a membrane electrode assembly (MEA) for electrochemical performance testing. The Pt- Co catalyst-based MEA showed comparable performance to an MEA fabri cated using a standard Pt black fuel cell catalyst. The main objective of this program has been to increase the overall efficiencies of fuel cell systems to support power for manned lunar bases. This work may also have an impact on terrestrial programs, possibly to support the effort to develop a carbon-free energy source. This catalyst can be used to fabricate high-efficiency fuel cell units that can be used in space as regenerative fuel cell systems, and terrestrially as primary fuel cells. Terrestrially, this technology will become increasingly important when transition to a hydrogen economy occurs.

  18. Nanoparticular metal oxide/anatase catalysts

    DEFF Research Database (Denmark)

    2010-01-01

    The present invention concerns a method of preparation of nanoparticular metal oxide catalysts having a narrow particle size distribution. In particular, the invention concerns preparation of nanoparticular metal oxide catalyst precursors comprising combustible crystallization seeds upon which...... the catalyst metai oxide is co-precipitated with the carrier metal oxide, which crystallization seeds are removed by combustion in a final calcining step. The present invention also concerns processes wherein the nanoparticular metal oxide catalysts of the invention are used, such as SCR (deNOx) reactions...

  19. Silica deactivation of bead VOC catalysts

    Energy Technology Data Exchange (ETDEWEB)

    Libanati, C.; Pereira, C.J. [Research Division, W. R. Grace and Co., Columbia, MD (United States); Ullenius, D.A. [Grace TEC Systems, De Pere, WI (United States)

    1998-01-15

    Catalytic oxidation is a key technology for controlling the emissions of Volatile Organic Compounds (VOCs) from industrial plants. The present paper examines the deactivation by silica of bead VOC catalysts in a flexographic printing application. Post mortem analyses of field-aged catalysts suggest that organosilicon compounds contained in the printing ink diffuse into the catalyst and deposit as silica particles in the micropores. Laboratory activity evaluation of aged catalysts suggests that silica deposition is non-selective and that silica masks the noble metal active site

  20. Nitrogen oxides storage catalysts containing cobalt

    Science.gov (United States)

    Lauterbach, Jochen; Snively, Christopher M.; Vijay, Rohit; Hendershot, Reed; Feist, Ben

    2010-10-12

    Nitrogen oxides (NO.sub.x) storage catalysts comprising cobalt and barium with a lean NO.sub.x storage ratio of 1.3 or greater. The NO.sub.x storage catalysts can be used to reduce NO.sub.x emissions from diesel or gas combustion engines by contacting the catalysts with the exhaust gas from the engines. The NO.sub.x storage catalysts can be one of the active components of a catalytic converter, which is used to treat exhaust gas from such engines.

  1. Radiolytically prepared Ni-Pd sols as catalysts for water photoreduction

    Energy Technology Data Exchange (ETDEWEB)

    Amouyal, E.; Georgopoulos, M.; Delcourt, M.O. (Paris-11 Univ., 91 - Orsay (FR). Lab. de Physico-Chimie des Rayonnements)

    1989-07-01

    Ni-Pd sols containing 10% Pd, prepared via radiolytic reduction, display a catalytic activity notably enhanced, compared to pure nickel sols, towards the water photoreduction to hydrogen. The test system is Ru(bipy){sub 3}{sup 2+}/methylviologen/N-phenylglycine: a favourable pH effect is shown at pH 2.5. Hydrogen evolution rate is not far from the optimal values obtained with platinum sols in acidic medium. These Ni-Pd aggregates are the first example of an aqueous colloid metal catalyst being improved by alloying effect.

  2. Cu-Au Alloys Using Monte Carlo Simulations and the BFS Method for Alloys

    Science.gov (United States)

    Bozzolo, Guillermo; Good, Brian; Ferrante, John

    1996-01-01

    Semi empirical methods have shown considerable promise in aiding in the calculation of many properties of materials. Materials used in engineering applications have defects that occur for various reasons including processing. In this work we present the first application of the BFS method for alloys to describe some aspects of microstructure due to processing for the Cu-Au system (Cu-Au, CuAu3, and Cu3Au). We use finite temperature Monte Carlo calculations, in order to show the influence of 'heat treatment' in the low-temperature phase of the alloy. Although relatively simple, it has enough features that could be used as a first test of the reliability of the technique. The main questions to be answered in this work relate to the existence of low temperature ordered structures for specific concentrations, for example, the ability to distinguish between rather similar phases for equiatomic alloys (CuAu I and CuAu II, the latter characterized by an antiphase boundary separating two identical phases).

  3. Neutron absorbing alloy

    Energy Technology Data Exchange (ETDEWEB)

    Hayashi, Masayuki

    1998-12-04

    The neutron absorbing alloy of the present invention comprises Ti or an alloy thereof as a mother material, to which from 2 to 40% by weight of Hf and Gd within a range of from 4 to 50% by weight in total are added respectively. Ti is excellent in specific strength, corrosion resistance and workability, and produces no noxious intermetallic compound with Hf and Gd. In addition, since the alloy can incorporate a great quantity of Hf and Gd, a neutron absorbing material having excellent neutron absorbing performance than usual and excellent in specific strength, corrosion resistance and workability can be manufactured conveniently and economically not by a special manufacturing method. (T.M.)

  4. Shape Memory Alloys

    Directory of Open Access Journals (Sweden)

    Deexith Reddy

    2016-07-01

    Full Text Available Shape memory alloys (SMAs are metals that "remember" their original shapes. SMAs are useful for such things as actuators which are materials that "change shape, stiffness, position, natural frequency, and other mechanical characteristics in response to temperature or electromagnetic fields" The potential uses for SMAs especially as actuators have broadened the spectrum of many scientific fields. The study of the history and development of SMAs can provide an insight into a material involved in cutting-edge technology. The diverse applications for these metals have made them increasingly important and visible to the world. This paper presents the working of shape memory alloys , the phenomenon of super-elasticity and applications of these alloys.

  5. Aids and Infectious Diseases (aid) Pmp 2013 Report

    Science.gov (United States)

    Buonaguro, Franco M.

    2014-07-01

    The AIDS and Infectious Diseases (AID) PMP of the WFS contributed this year with a session on August 22nd to the Plenary Sessions of the International Seminars on Planetary Emergencies and Associated Meetings--46th Session: The Role of Science in the Third Millennium (Erice, 19-24 August 2013). Furthermore a workshop on August 24th was organized...

  6. Double Glow Plasma Surface Alloyed Burn-resistant Titanium Alloy

    Institute of Scientific and Technical Information of China (English)

    ZHANG Ping-ze; XU Zhong; HE Zhi-yong; ZHANG Gao-hui

    2004-01-01

    Conventional titanium alloy may be ignited and burnt under high temperature, high pressure and high gas flow velocity condition. In order to avoid this problem, we have developed a new kind of burn-resistant titanium alloy-double glow plasma surface alloying burn-resistant titanium alloy. Alloying element Cr, Mo, Cu are induced into the Ti-6Al-4V and Ti-6.5Al-0.3Mo-l.5Zr-0.25Si substrates according to double glow discharge phenomenon, Ti-Cr ,Ti-Mo, Ti-Cu binary burn-resistant alloy layers are formed on the surface of Ti-6Al-4V and Ti-6.5Al-0.3Mo-l.5Zr-0.25Si alloys. The depth of the surface burn-resistant alloy layer can reach to above 200 microns and alloying element concentration can reach 90%.Burn-resistant property experiments reveal that if Cr concentration reach to 14%, Cu concentration reach to 12%, Mo concentration reach to 10% in the alloying layers, ignition and burn of titanium alloy can be effectively avoided.

  7. Double Glow Plasma Surface Alloyed Burn-resistant Titanium Alloy

    Institute of Scientific and Technical Information of China (English)

    ZHANGPing-ze; XUZhong; HEZhi-yong; ZHANGGao-hui

    2004-01-01

    Conventional titanium alloy may be ignited and burnt under high temperature, high pressure and high gas flow velocity condition. In order to avoid this problem, we have developed a new kind of burn-resistant titanium alloy-double glow plasma surface alloying burn-resistant titanium alloy. Alloying element Cr, Mo, Cu are induced into the Ti-6A1-4V and Ti-6.5Al-0.3Mo-1.5Zr-0.25Si substrates according to double glow discharge phenomenon, Ti-Cr ,Ti-Mo, Ti-Cu binary burn-resistant alloy layers are formed on the surface of Ti-6A1-4V and Ti-6.5Al-0.3Mo-1.5Zr-0.25Si alloys. The depth of the surface burn-resistant alloy layer can reach to above 200 microns and alloying element concentration can reach 90%. Burn-resistant property experiments reveal that if Cr concentration reach to 14%, Cu concentration reach to 12%, Mo concentration reach to 10% in the alloying layers, ignition and burn of titanium alloy can be effectively avoided.

  8. Ergogenic Aids and Supplements.

    Science.gov (United States)

    Porrini, Marisa; Del Boʼ, Cristian

    2016-01-01

    Great interest is currently shown for the contribution of nutrition to optimize training and athletic performance, and a considerable debate exists about the potential ergogenic value of several dietary supplements. However, most of the products used by athletes do not provide sufficient scientific evidence regarding their efficacy in enhancing physical performance as well as their specificity of action and safety. For this reason, sport nutrition professionals need skills in evaluating the scientific value of papers and advertisements on ergogenic aids and supplements in order to support athletes in their choice. In the present chapter, the efficacy of some of the most popular supplements used by athletes and sport practitioners will be discussed. Particular attention will be devoted to amino acids and derivatives, caffeine and caffeinated energy drinks, and some antioxidants.

  9. Learning to aid learning.

    Science.gov (United States)

    Richards, Jacqui

    2016-01-01

    The National Health Service (NHS) is one of the largest employers in the world and, with 1.3 million staff, the biggest employer in Europe. With over three hundred different careers on offer (NHS 2015), the acquisition of skills and qualifications, through academic and clinical training, is an integral part of day-to-day life in the health service. As such, mentoring has become a significant feature in the preparation of healthcare professionals, to support students and ensure learning needs and experiences are appropriate to competency. This article examines the mentor's role, in relation to a teaching innovation designed to address students' identified learning needs to meet the requirements of the multi-professional learning and assessment in practice course NM6156. The effectiveness of the aids to learning will be assessed through an online quiz, and its usefulness will be analysed with reference to educational theories of learning and development.

  10. AIDS and sex tourism.

    Science.gov (United States)

    Herold, E S; Van Kerkwijk, C

    1992-01-01

    Tourists traveling internationally lower their inhibitions and take greater risks than they would typically in their home cultures. Loneliness, boredom, and a sense of freedom contribute to this behavioral change. Some tourists travel internationally in search of sexual gratification. This motivation may be actively conscious or subconscious to the traveler. Billed as romantic with great natural beauty, Thailand, the Philippines, Brazil, the Dominican Republic, and Kenya are popular destinations of tourists seeking sex. The Netherlands and countries in eastern Europe are also popular. With most initial cases of HIV infection in Europe having histories of international travel, mass tourism is a major factor in the international transmission of AIDS. While abroad, tourists have sex with casual partners, sex workers, and/or other tourists. Far from all tourists, however, carry and consistently use condoms with these partners. One study found female and non white travelers to be less likely than Whites and males to carry condoms. The risk of HIV infection increases in circumstances where condoms are not readily available in the host country and/or are of poor quality. Regarding actual condom use, a study found only 34% of sex tourists from Switzerland to consistently use condoms while abroad. 28% of men in an STD clinic in Melbourne, Australia, reported consistent condom use in sexual relations while traveling in Asia; STDs were identified in 73% of men examined. The few studies of tourists suggest that a significant proportion engage in risky behavior while traveling. HIV prevalence is rapidly increasing in countries known as destinations for sex tourism. High infection rates are especially evident among teenage sex workers in Thailand. Simply documenting the prevalence of risky behavior among sex tourists will not suffice. More research is needed on travelers and AIDS with particular attention upon the motivating factors supporting persistent high-risk behavior.

  11. Preparation of Gold-Silver Alloy Nanoparticles Supported on NiCo2O4 Spinel Oxides for the Treatment of CO in Atmosphere.

    Science.gov (United States)

    Chinh, Vu Duc; Trung, Nguyen Quoc

    2015-06-01

    Heterometallics are an important class of catalysts. Alloy nanoparticles have higher activities than monometallic counterparts in catalysis because of the synergistic effects between the two metals. The Ni-Co composition, which is a typical alloy chemical composition, has a remarkable effect on catalytic activity. Ni-Co mixed oxides were characterized by thermal effect, X-ray diffraction, energy dispersive X-ray spectroscopy, Scanning Electron Microscope and BET specific surface area techniques. X-ray diffraction show that the formation of small spinel oxides nanoparticles. Very small amounts of gold-silver alloy nanoparticles deposited on such mixed oxides improve the catalytical activity for CO oxidation.

  12. Strip Casting of High Performance Structural Alloys

    Institute of Scientific and Technical Information of China (English)

    S S Park; J G Lee; Nack J Kim

    2004-01-01

    There exists a great need for the development of high performance alloys due to increasing demands for energy conservation and environmental protection. Application of strip casting shows a strong potential for the improvement of properties of existing alloys and also for the development of novel alloy systems with superior properties. The present paper reviews our Center's activities in the development of high performance alloys by strip casting. Examples include (1) Al alloys, (2) wrought Mg alloys, and (3) bulk metallic glass (BMG) alloys.

  13. Pemilihan Bahan Alloy Untuk Konstruksi Gigitiruan

    OpenAIRE

    Medila Dahlan

    2008-01-01

    Pada kedokteran gigi bahan alloy sangat banyak digunakan dalam segala bidang. Dalam pembuatan konstruksi gigitiman biasanya digunakan alloy emas, alloy kobalt kromium, alloy nikei kromium dan alloy stainless steel sebagai komponen gigitiman kerangka logam serta pembuatan mahkota dan jembatan. Pemilihan bahan alloy dapat dilakukan berdasarkan sifat yang dimiiiki oleh masing-masing bahan alloy sehingga akan didapat hasil konstmksi gigitiruan yang memuaskan. Pada pemakaiannya didaiam mulut...

  14. Tungsten Alloy Outgassing Measurements

    CERN Document Server

    Rutherfoord, John P; Shaver, L

    1999-01-01

    Tungsten alloys have not seen extensive use in liquid argon calorimeters so far. Because the manufacturing process for tungsten is different from the more common metals used in liquid argon there is concern that tungsten could poison the argon thereby creating difficulties for precision calorimetry. In this paper we report measurements of outgassing from the tungsten alloy slugs proposed for use in the ATLAS FCal module and estimate limits on potential poisoning with reasonable assumptions. This estimate gives an upper limit poisoning rate of

  15. Preparation and characterization of planar Ni–Au bimetallic model catalysts

    Energy Technology Data Exchange (ETDEWEB)

    Yang, Fan, E-mail: fan.yang@chem.tamu.edu; Yao, Yunxi; Yan, Zhen; Min, Hlaing; Goodman, D. Wayne

    2013-10-15

    Ni–Au bimetallic model catalysts were prepared as thin films on Re(0 0 0 1) or Ru(0 0 0 1) single crystal substrates. Surface compositions and electronic structures of the Ni–Au thin films were characterized by low energy ion scattering spectroscopy and X-ray photoelectron spectroscopy, respectively. Surface alloys were prepared by annealing Ni–Au thin films from 500 to 800 K, resulting in substantial surface enrichment of Au. Annealing a Ni–Au thin film with a 1:1 bulk composition ratio at 700 K for 10 min resulted in a surface alloy with 84% (atomic concentration) of Au in the outermost surface layer. The surface atomic structure was investigated using CO as probe molecules, which exclusively adsorbs on the Ni atoms rather than on the Au atoms at room temperature. Polarization modulation infrared reflection absorption spectroscopy of CO adsorption on Ni–Au surface alloys showed that CO adsorption on two-fold bridge sites decreased and finally disappeared with an increase of Au surface concentration. The absence of Ni bridge site CO adsorption indicated that Ni atoms were isolated by Au atoms on Ni–Au alloyed surface.

  16. The role of Pt and Pd in enhancing the conversion of sorbitol to hydrogen over supported Ni-Pt and Ni-Pd catalysts

    Energy Technology Data Exchange (ETDEWEB)

    Tanksale, A.; Lu, G.Q. [Queensland Univ., Brisbane (Australia); Beltramini, J.N. [Queensland Univ., Brisbane (Australia). ARC Centre of Excellence for Functional Nanomaterials

    2009-07-01

    This study investigated the enhanced activity of bimetallic nickel-platinum (Ni-Pt) and nickel-palladium (Ni-Pd) catalysts for the production of hydrogen from reformed biomass-based products. The catalysts were prepared on an aluminum oxide (Al203) nanofibre. Mesoporous zirconia and composite silica-zirconia-ceria were used to determine the role of noble metals and supports. Desorption, oxidation, and temperature programmed reduction studies were conducted to investigate metal-metal and metal-support interactions. The study showed that Pt and Pd additions increased the reducibility of Ni catalysts. The bimetallic catalysts exhibited rates of hydrogen production 6 times higher than rates observed in pure metal catalysts. Sorbitol conversion increased from 35 per cent for the Ni catalyst to 62 per cent for the Ni-Pt catalyst. It was concluded that the alloying effect of the Ni-Pt and Ni-Pd systems lowered the carbon monoxide (CO) adsorption heat, and facilitated removal of the adsorbed CO by the water gas shift reaction.

  17. Communication: Enhanced oxygen reduction reaction and its underlying mechanism in Pd-Ir-Co trimetallic alloys

    Science.gov (United States)

    Ham, Hyung Chul; Manogaran, Dhivya; Lee, Kang Hee; Kwon, Kyungjung; Jin, Seon-ah; You, Dae Jong; Pak, Chanho; Hwang, Gyeong S.

    2013-11-01

    Based on a combined density functional theory and experimental study, we present that the electrochemical activity of Pd3Co alloy catalysts toward oxygen reduction reaction (ORR) can be enhanced by adding a small amount of Ir. While Ir tends to favorably exist in the subsurface layers, the underlying Ir atoms are found to cause a substantial modification in the surface electronic structure. As a consequence, we find that the activation barriers of O/OH hydrogenation reactions are noticeably lowered, which would be mainly responsible for the enhanced ORR activity. Furthermore, our study suggests that the presence of Ir in the near-surface region can suppress Co out-diffusion from the Pd3Co substrate, thereby improving the durability of Pd-Ir-Co catalysts. We also discuss the relative roles played by Ir and Co in enhancing the ORR activity relative to monometallic Pd catalysts.

  18. Thermodynamic Properties of Supported Catalysts

    Energy Technology Data Exchange (ETDEWEB)

    Gorte, Raymond J.

    2014-03-26

    The goals of this work were to develop Coulometric Titration as a method for characterizing the thermodynamic redox properties of oxides and to apply this technique to the characterization of ceria- and vanadia-based catalysts. The redox properties of ceria and vanadia are a major part of what makes these materials catalytically active but their properties are also dependent on their structure and the presence of other oxides. Quantifying these properties through the measurement of oxidation energetics was the goal of this work.

  19. New Trends in Gold Catalysts

    Directory of Open Access Journals (Sweden)

    Leonarda F. Liotta

    2014-07-01

    Full Text Available Gold is an element that has fascinated mankind for millennia. The catalytic properties of gold have been a source of debate, due to its complete chemical inertness when in a bulk form, while it can oxidize CO at temperatures as low as ~200 K when in a nanocrystalline state, as discovered by Haruta in the late 1980s [1]. Since then, extensive activity in both applied and fundamental research on gold has been initiated. The importance of the catalysis by gold represents one of the fasted growing fields in science and is proven by the promising applications in several fields, such as green chemistry and environmental catalysis, in the synthesis of single-walled carbon nanotubes, as modifiers of Ni catalysts for methane steam and dry reforming reactions and in biological and electrochemistry applications. The range of reactions catalyzed by gold, as well as the suitability of different supports and the influence of the preparation conditions have been widely explored and optimized in applied research [2]. Gold catalysts appeared to be very different from the other noble metal-based catalysts, due to their marked dependence on the preparation method, which is crucial for the genesis of the catalytic activity. Several methods, including deposition-precipitation, chemical vapor deposition and cation adsorption, have been applied for the preparation of gold catalysts over reducible oxides, like TiO2. Among these methods, deposition-precipitation has been the most frequently employed method for Au loading, and it involves the use of tetrachloroauric (III acid as a precursor. On the other hand, the number of articles dealing with Au-loaded acidic supports is smaller than that on basic supports, possibly because the deposition of [AuCl4]− or [AuOHxCl4−x]− species on acidic supports is difficult, due to their very low point of zero charge. Despite this challenge, several groups have reported the use of acidic zeolites as supports for gold. Zeolites

  20. Off-gas catalyst. Abgaskatalysator

    Energy Technology Data Exchange (ETDEWEB)

    Saris, L.; Kloeck, H.

    1987-02-19

    The invention deals with a waste gas catalyst with a thermo-resistant SiO{sub 2} and Al{sub 2}O{sub 3} containing carrier of snarled ceramic fibres which form between themselves the flow paths for the waste gas to be purified and which are coated with platinum, palladium and/or rhodium. The ceramic fibres forming the carrier consist of SiO{sub 2} and Al{sub 2}O{sub 3} and have a diameter of 1 to 10 {mu}m. (orig./RB).