Recovery of hydrogen from impurities using a palladium membrane reactor

International Nuclear Information System (INIS)

Willms, R.S.; Okuno, K.

1993-01-01

One of the important steps in processing the exhaust from a fusion reactor is recovering tritium which is incorporated into molecules such as water and methane. One device which may prove to be very effective for this purpose is a palladium membrane reactor. This is a reactor which incorporates a Pd/Ag membrane in the reactor geometry. Reactions such as water gas shift, steam reforming and methane cracking can be carried out over the reactor catalyst, and the product hydrogen can be simultaneously removed from the reacting mixture. Because product is removed, greater than usual conversions can be obtained. In addition ultrapure hydrogen is produced, eliminating the need for an additional processing step. A palladium membrane reactor has been built and tested with three different catalysts. Initial results with a Ni-based catalyst show that it is very effective at promoting all three reactions listed above. Under the proper conditions, hydrogen recoveries approaching 100% have been observed. This study serves to experimentally validate the palladium membrane reactor as potentially important tool for fusion fuel processing

Sol-gel synthesized of nanocomposite palladium-alumina ceramic membrane for H{sub 2} permeability: Preparation and characterization

Energy Technology Data Exchange (ETDEWEB)

Ahmad, A.L.; Mustafa, N.N.N. [School of Chemical Engineering, Engineering Campus, Universiti Sains Malaysia, Seri Ampangan, 14300 Nibong Tebal, Penang (Malaysia)

2007-08-15

Palladium-alumina membrane with mesopore and narrow pore size distribution was prepared by the sol-gel method. Effect of the finely dispersed metal on the microstructure and the characteristic properties of the palladium-alumina membrane were investigated. Observations were made on membrane weight loss, morphology, pore structure, pore size, surface area, pore surface fractal and membrane's crystal structure. Autosorb analysis, X-ray Diffraction (XRD), Scanning Electron Microscopy (SEM) and Fourier Transform Infrared (FTIR) analysis were employed in the membrane characterization. Autosorb analysis found that, BET surface area decreased and pore size of the membrane increased with the increasing of calcinations temperature (500-1100{sup o}C) and with the increasing of palladium amount in the membrane. FTIR and TG/DTA analysis show that the suitable temperature for calcinations of palladium-alumina membrane is at 700{sup o}C. Palladium metals are highly dispersed at calcinations temperature of 700{sup o}C as observed by TEM analysis. The fine crystallinity of the palladium and {gamma}-alumina phase was obtained after calcined at 700{sup o}C. The SEM morphology shows a smooth and free crack layer of palladium-alumina membrane after repeating the process of dipping, drying and calcinations at temperature of 700{sup o}C. The membrane also successfully coated with a good adhesion on support. The thickness of the final membrane layer was estimated as 9{mu} m. (author)

Development of polymeric palladium-nanoparticle membrane-installed microflow devices and their application in hydrodehalogenation.

Science.gov (United States)

Yamada, Yoichi M A; Watanabe, Toshihiro; Ohno, Aya; Uozumi, Yasuhiro

2012-02-13

We have developed a variety of polymeric palladium-nanoparticle membrane-installed microflow devices. Three types of polymers were convoluted with palladium salts under laminar flow conditions in a microflow reactor to form polymeric palladium membranes at the laminar flow interface. These membranes were reduced with aqueous sodium formate or heat to create microflow devices that contain polymeric palladium-nanoparticle membranes. These microflow devices achieved instantaneous hydrodehalogenation of aryl chlorides, bromides, iodides, and triflates by 10-1000 ppm within a residence time of 2-8 s at 50-90 °C by using safe, nonexplosive, aqueous sodium formate to quantitatively afford the corresponding hydrodehalogenated products. Polychlorinated biphenyl (10-1000 ppm) and polybrominated biphenyl (1000 ppm) were completely decomposed under similar conditions, yielding biphenyl as a fungicidal compound. Copyright © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Morphology of one-time coated palladium-alumina composite membrane prepared by sol-gel process and electroless plating technique

Science.gov (United States)

Sari, R.; Dewi, R.; Pardi; Hakim, L.; Diana, S.

2018-03-01

Palladium coated porous alumina ceramic membrane tube was obtained using a combination of sol-gel process and electroless plating technique. The thickness, structure and composition of palladium-alumina composite membrane were analyzed by transmission electron microscopy (TEM), scanning electron microscopy (SEM), energy-dispersive X-ray (EDX), and atomic force microscopy (AFM). Palladium particle size was 6.18 to 7.64 nm. Palladium membrane with thickness of approximately 301.5 to 815.1 nm was formed at the outer surface of the alumina layer. EDX data confirmed the formation of palladium-alumina membrane containing 45% of palladium. From this research it shows the combination of sol-gel process and electroless plating technique with one-time coating can produce a homogeneous and smoother palladium nano layer film on alumina substrate.

Metallurgical characterization of new palladium-containing cobalt chromium and nickel chromium alloys

Science.gov (United States)

Puri, Raghav

Recently introduced to the market has been an entirely new subclass of casting alloy composition whereby palladium (˜25 wt%) is added to traditional base metal alloys such as CoCr and NiCr. Objectives. The purpose of this study was to evaluate the microstructure and Vickers hardness of two new CoPdCr and one new NiPdCr alloy and compare them to traditional CoCr and NiCr alloys. Methods. The casting alloys investigated were: CoPdCr-A (Noble Crown NF, The Argen Corporation), CoPdCr-I (Callisto CP+, Ivoclar Vivadent), NiPdCr (Noble Crown, Argen), CoCr (Argeloy N.P. Special, Argen), and NiCr (Argeloy N.P. Star, Argen). As-cast cylindrical alloy specimens were mounted in epoxy resin and prepared with standard metallographic procedures, i.e. grinding with successive grades of SiC paper and polishing with alumina suspensions. The alloys were examined with an optical microscope, SEM/EPMA, and XRD to gain insight into their microstructure, composition, and crystal structure. Vickers hardness (VHN) was measured and statistically analyzed by one way ANOVA and Tukey's HSD test (alpha=0.05). Results. Optical microscopy showed a dendritic microstructure for all alloys. The Pd-containing alloys appear to possess a more complex microstructure. SEM/EPMA showed Cr to be rather uniformly distributed in the matrix with palladium tending to be segregated apart from Mo and Ni or Co. Areas of different composition may explain the poor electrochemical results noted in previous studies. XRD suggested the main phase in the Ni-containing solutions was a face centered cubic Ni solid solution, whereas the CoCr exhibited a hexagonal crystal structure that was altered to face centered cubic when Pd was included in the composition. For Vickers hardness, the Co-containing alloys possessed a greater hardness than the Ni-containing alloys. However, the incorporation of Pd in CoCr and NiCr had only a slight effect on microhardness. Conclusion. Overall, the inclusion of palladium increases the

Multilayer sulfur-resistant composite metal membranes and methods of making and repairing the same

Science.gov (United States)

Way, J. Douglas; Hatlevik, Oyvind

2014-07-15

The invention relates to thin, hydrogen-permeable, sulfur-resistant membranes formed from multi-layers of palladium or palladium-alloy coatings on porous, ceramic or metal supports, methods of making these membranes, methods of repairing layers of these membranes and devices that incorporate these membranes.

ERRATUM Study of microstructure in vanadium–palladium alloys by ...

Indian Academy of Sciences (India)

WINTEC

ERRATUM. Study of microstructure in vanadium–palladium alloys by X-ray diffraction technique. J Ghosh, S K Chattopadhyay, A K Meikap, S K Chatterjee and P Chatterjee 2007 Bull. Mater. Sci. 30 447–454. In page 448, under §2.1 Warren–Averbach method, after equation (1), the sentence starting with “Then the domain ...

Mechanical, electrical, and thermal expansion properties of carbon nanotube-based silver and silver-palladium alloy composites

Science.gov (United States)

Pal, Hemant; Sharma, Vimal

2014-11-01

The mechanical, electrical, and thermal expansion properties of carbon nanotube (CNT)-based silver and silver-palladium (10:1, w/w) alloy nanocomposites are reported. To tailor the properties of silver, CNTs were incorporated into a silver matrix by a modified molecular level-mixing process. CNTs interact weakly with silver because of their non-reactive nature and lack of mutual solubility. Therefore, palladium was utilized as an alloying element to improve interfacial adhesion. Comparative microstructural characterizations and property evaluations of the nanocomposites were performed. The structural characterizations revealed that decorated type-CNTs were dispersed, embedded, and anchored into the silver matrix. The experimental results indicated that the modification of the silver and silver-palladium nanocomposite with CNT resulted in increases in the hardness and Young's modulus along with concomitant decreases in the electrical conductivity and the coefficient of thermal expansion (CTE). The hardness and Young's modulus of the nanocomposites were increased by 30%-40% whereas the CTE was decreased to 50%-60% of the CTE of silver. The significantly improved CTE and the mechanical properties of the CNT-reinforced silver and silver-palladium nanocomposites are correlated with the intriguing properties of CNTs and with good interfacial adhesion between the CNTs and silver as a result of the fabrication process and the contact action of palladium as an alloying element.

Adlayers of palladium particles and their aggregates on porous polypropylene hollow fiber membranes as hydrogenization contractors/reactors

NARCIS (Netherlands)

Volkov, V.V.; Lebedeva, V.I.; Petrova, I.V.; Bobyl, A.V.; Konnikov, S.G.; Roldughin, V.I.; Erkel, J. van; Tereshchenko, G.F.

2011-01-01

Principal approaches for the preparation of catalytic membrane reactors based on polymer membranes containing palladium nanoparticles and for the description of their characteristics are presented. The method for the development of adlayers composed of palladium nanoparticles and their aggregates on

Low Temperature Steam Methane Reforming Over Ni Based Catalytic Membrane Prepared by Electroless Palladium Plating.

Science.gov (United States)

Lee, Sang Moon; Hong, Sung Chang; Kim, Sung Su

2018-09-01

A Pd/Ni-YSZ porous membrane with different palladium loadings and hydrazine as a reducing reagent was prepared by electroless plating and evaluated for the steam methane reforming activity. The steam-reforming activity of a Ni-YSZ porous membrane was greatly increased by the deposition of 4 g/L palladium in the low-temperature range (600 °C). With an increasing amount of reducing reagent, the Pd clusters were well dispersed on the Ni-YSZ surface and were uniform in size (∼500 nm). The Pd/Ni-YSZ catalytic porous membrane prepared by 1 of Pd/hydrazine ratio possessed an abundant amount of metallic Pd. The optimal palladium loadings and Pd/hydrazine ratio increased the catalytic activity in both the steam-reforming reaction and the Pd dispersion.

Cost-Effective Method for Producing Self Supported Palladium Alloy Membranes for Use in Efficient Production of Coal Derived Hydrogen

Energy Technology Data Exchange (ETDEWEB)

K. Coulter

2008-03-31

Southwest Research Institute{reg_sign} (SwRI{reg_sign}) has utilized its expertise in large-area vacuum deposition methods to conduct research into the fabrication of dense, freestanding Pd-alloy membranes that are 3-5 microns thick and over 100 in{sup 2} in area. The membranes were deposited onto flexible and rigid supports that were subsequently removed and separated using novel techniques developed over the course of the project. Using these methods, the production of novel alloy compositions centered around the Pd-Cu system were developed with the objective of producing a thermally stable, nano-crystalline grain structure with the highest flux recorded as 242 SCFH/ft{sup 2} for a 2 {micro}m thick Pd{sub 53}Cu{sub 47} at 400 C and 20 psig feed pressure which when extrapolated is over twice the 2010 Department of Energy pure H{sub 2} flux target. Several membranes were made with the same permeability, but with different thicknesses and these membranes were highly selective. Researchers at the Colorado School of Mines supported the effort with extensive testing of experimental membranes as well as design and modeling of novel alloy composite structures. IdaTech provided commercial bench testing and analysis of SwRI-manufactured membranes. The completed deliverables for the project include test data on the performance of experimental membranes fabricated by vacuum deposition and several Pd-alloy membranes that were supplied to IdaTech for testing.

Microfabricated hydrogen sensitive membranes

Energy Technology Data Exchange (ETDEWEB)

Naddaf, A.; Kraetz, L. [Lehrstuhl fuer Thermische Verfahrenstechnik, Technische Universitaet Kaiserslautern (Germany); Detemple, P.; Schmitt, S.; Hessel, V. [Institut fuer Mikrotechnik Mainz GmbH, Mainz (Germany); Faqir, N. [University of Jordan, Amman (Jordan); Bart, H.J.

2009-01-15

Thin, defect-free palladium, palladium/copper and palladium/silver hydrogen absorbing membranes were microfabricated. A dual sputtering technique was used to deposit the palladium alloy membranes of only 1 {mu}m thickness on a nonporous silicon substrate. Advanced silicon etching (ASE) was applied on the backside to create a mechanically stable support structure for the thin films. Performance evaluation was carried out for different gases in a temperature range of 20 C to 298 C at a constant differential pressure of 110 kPa at the two sides of the membrane. The composite membranes show an excellent permeation rate of hydrogen, which appears to be 0.05 Pa m{sup 3} s{sup -1} and 0.01.10{sup -3} Pa m{sup 3} s{sup -1} at 20 C for the microfabricated 23 % silver and the 53 % copper composite membranes, respectively. The selectivity to hydrogen over a gas mixture containing, in addition to hydrogen, carbon monoxide, carbon dioxide and nitrogen was measured. The mass spectrometer did not detect any CO{sub 2} or CO, showing that the membrane is completely hydrogen selective. The microfabricated membranes exhibit both high mechanical strength (they easily withstand pressures up to 4 bar) and high thermal stability (up to 650 C). (Abstract Copyright [2009], Wiley Periodicals, Inc.)

Hydrogen sensor based on palladium-yttrium alloy nanosheet

Energy Technology Data Exchange (ETDEWEB)

Wang, Boyi [Queensland Micro- and Nanotechnology Centre, Griffith University, Nathan, QLD 4111 (Australia); Zhu, Yong, E-mail: y.zhu@griffith.edu.au [Queensland Micro- and Nanotechnology Centre, Griffith University, Nathan, QLD 4111 (Australia); Chen, Youping; Song, Han; Huang, Pengcheng [School of Mechanical Science and Engineering, Huazhong University of Science and Technology, Wuhan, 430074 (China); Dao, Dzung Viet [Queensland Micro- and Nanotechnology Centre, Griffith University, Nathan, QLD 4111 (Australia)

2017-06-15

This paper presents a hydrogen sensor based on palladium-yttrium (Pd-Y) alloy nanosheet. Zigzag-shaped Pd-Y nanosheet with a thickness of 19.3 nm was deposited on a quartz substrate by using an ultrahigh-vacuum magnetron sputtering system and shadow mask. The atomic ratio of palladium to yttrium in the nanosheet was 0.92/0.08. The fabrication process was simple and low-cost, and the sensor can be mass-produced. The experimental results show the sensor has a superior sensitivity, reversibility, and reproducibility. The resistive-based hydrogen detection mechanism in this research is much simpler and more compact compared to the optical-based detection method. - Highlights: • Pd-Y sensing element was fabricated using a magnetron sputtering system and shadow mask. • The Pd-Y compound consisted of 92% Pd and 8% Y. • The fabrication process was simple, low-cost, and mass-production compatible. • The sensor showed superior sensitivity, reversibility, and reproducibility to hydrogen gas. • The device is more compact than the optical-based counterpart.

Hydrogen sensor based on palladium-yttrium alloy nanosheet

International Nuclear Information System (INIS)

Wang, Boyi; Zhu, Yong; Chen, Youping; Song, Han; Huang, Pengcheng; Dao, Dzung Viet

2017-01-01

This paper presents a hydrogen sensor based on palladium-yttrium (Pd-Y) alloy nanosheet. Zigzag-shaped Pd-Y nanosheet with a thickness of 19.3 nm was deposited on a quartz substrate by using an ultrahigh-vacuum magnetron sputtering system and shadow mask. The atomic ratio of palladium to yttrium in the nanosheet was 0.92/0.08. The fabrication process was simple and low-cost, and the sensor can be mass-produced. The experimental results show the sensor has a superior sensitivity, reversibility, and reproducibility. The resistive-based hydrogen detection mechanism in this research is much simpler and more compact compared to the optical-based detection method. - Highlights: • Pd-Y sensing element was fabricated using a magnetron sputtering system and shadow mask. • The Pd-Y compound consisted of 92% Pd and 8% Y. • The fabrication process was simple, low-cost, and mass-production compatible. • The sensor showed superior sensitivity, reversibility, and reproducibility to hydrogen gas. • The device is more compact than the optical-based counterpart.

Antibiofilm effect enhanced by modification of 1,2,3-triazole and palladium nanoparticles on polysulfone membranes

KAUST Repository

Cheng, Hong

2015-01-01

Biofouling impedes the performance of membrane bioreactors. In this study, we investigated the antifouling effects of polysulfone membranes that were modified by 1,2,3-triazole and palladium nanoparticles. The membranes to be tested were embedded within a drip flow biofilm reactor, and Pseudomonas aeruginosa PAO1 was inoculated and allowed to establish biofilm on the tested membranes. It was found that 1,2,3-triazole and palladium nanoparticles can inhibit the bacterial growth in aerobic and anaerobic conditions. The decrease in bacterial growth was observed along with a decrease in the amount of total polysaccharide and Pel polysaccharide within the biofilm matrix but not the protein content.

Antibiofilm effect enhanced by modification of 1,2,3-triazole and palladium nanoparticles on polysulfone membranes

KAUST Repository

Cheng, Hong

2015-08-01

Biofouling impedes the performance of membrane bioreactors. In this study, we investigated the antifouling effects of polysulfone membranes that were modified by 1,2,3-triazole and palladium nanoparticles. The membranes to be tested were embedded within a drip flow biofilm reactor, and Pseudomonas aeruginosa PAO1 was inoculated and allowed to establish biofilm on the tested membranes. It was found that 1,2,3-triazole and palladium nanoparticles can inhibit the bacterial growth in aerobic and anaerobic conditions. The decrease in bacterial growth was observed along with a decrease in the amount of total polysaccharide and Pel polysaccharide within the biofilm matrix but not the protein content.

A simple approach to uniform PdAg alloy membranes: Comparative study of conventional and silver concentration-controlled co-plating

KAUST Repository

Zeng, Gaofeng

2014-03-01

An Ag-controlled co-plating method was developed for the preparation of palladium/silver alloy membranes on porous tubular alumina supports. By controlling the feed rate of Ag to the Pd bath, the concentration of the silver in the plating bath was restricted during the course of plating. As a result, preferential deposition of silver at the beginning was suppressed and uniform dispersion of silver inside the membrane with silver composition in the desired range was achieved. Ultrathin (∼2.5 μm) PdAg alloy membranes with uniform silver composition of ∼25% were successfully obtained. The membrane showed a hydrogen permeance of 0.88 mol m-2 s-1 and pure-gas H2/N2 selectivity of 2140 at 823 K with ΔP = 100 kPa. Only one hydride phase existed in the studied temperature range from 373 to 823 K with ΔPH=100kPa. Direct comparisons with the conventional simply-mixed co-plating method showed that membranes made by the novel Ag-controlled co-plating method had much more uniform silver distribution, smoother surface, denser membrane structure, higher utilization rate of metal sources, and shorter alloying time. © 2013, Hydrogen Energy Publications, LLC. Published by Elsevier Ltd. All rights reserved.

A simple approach to uniform PdAg alloy membranes: Comparative study of conventional and silver concentration-controlled co-plating

KAUST Repository

Zeng, Gaofeng; Shi, Lei; Liu, Yunyang; Zhang, Yanfeng; Sun, Yuhan

2014-01-01

An Ag-controlled co-plating method was developed for the preparation of palladium/silver alloy membranes on porous tubular alumina supports. By controlling the feed rate of Ag to the Pd bath, the concentration of the silver in the plating bath was restricted during the course of plating. As a result, preferential deposition of silver at the beginning was suppressed and uniform dispersion of silver inside the membrane with silver composition in the desired range was achieved. Ultrathin (∼2.5 μm) PdAg alloy membranes with uniform silver composition of ∼25% were successfully obtained. The membrane showed a hydrogen permeance of 0.88 mol m-2 s-1 and pure-gas H2/N2 selectivity of 2140 at 823 K with ΔP = 100 kPa. Only one hydride phase existed in the studied temperature range from 373 to 823 K with ΔPH=100kPa. Direct comparisons with the conventional simply-mixed co-plating method showed that membranes made by the novel Ag-controlled co-plating method had much more uniform silver distribution, smoother surface, denser membrane structure, higher utilization rate of metal sources, and shorter alloying time. © 2013, Hydrogen Energy Publications, LLC. Published by Elsevier Ltd. All rights reserved.

Ratio of dialytic coefficients of hydrogen and tritium in permeation through palladium alloy film

International Nuclear Information System (INIS)

Fujita, Haruyuki; Fujita, Kunio; Sakamoto, Hiroshi; Higashi, Kunio; Okada, Sakae.

1982-01-01

The dialytic coefficient for hydrogen is especially large in palladium and its alloys. Recently, with the research on fusion reactors, the dialytic coefficient of tritium permeating through solids and its isotopic effect have been the object of interest. The ratio of the dialytic coefficients of tritium and hydrogen has been usually assumed to be 3. The measurement of the dialytic coefficient in solids using pure tritium is practically difficult. Therefore, the authors carried out the experiment to determine the ratio of the dialytic coefficients of pure T 2 and pure H 2 by permeating the mixed gas of T and H through Pd-Au-Ag alloy. The mixed hydrogen gas was filled in a separation cell containing a palladium alloy tube, and the separation factor of tritium and hydrogen was measured by changing pressure, flow rate and temperature. The separation factor depends mainly on the relative dialytic coefficients of tritium and hydrogen, therefore, the ratio of dialytic coefficients can be determined by the simple analysis of the experimental results. This experimental method is suitable to determine the relative value of dialytic coefficients, and the obtained ratio was about 2.1. (Kako, I.)

Fabrication of palladium nanoparticles immobilized on an amine-functionalized ceramic membrane support using a nanoparticulate colloidal impregnation method with enhanced catalytic properties

Energy Technology Data Exchange (ETDEWEB)

Du, Yan; Chen, Rizhi [Nanjing Tech University, Nanjing (China)

2015-09-15

An efficient and reusable catalyst was developed by depositing palladium nanoparticles on an amine-functionalized ceramic membrane support using a nanoparticulate colloidal impregnation method. The as-prepared Pdloaded ceramic membrane support was characterized by XRD, SEM, EDS, TEM, XPS, ICP, and its catalytic properties were investigated in the liquid-phase p-nitrophenol hydrogenation. A comparative study was also made with the palladium nanoparticles deposited on an amine-functionalized ceramic membrane support by an impregnation-reduction method. The palladium nanoparticles could be homogeneously immobilized on the ceramic membrane support surface, and exhibited excellent catalytic performance in the p-nitrophenol hydrogenation. The catalytic activity of the Pdloaded ceramic membrane support prepared by the nanoparticulate colloidal impregnation method increased by 16.6% compared to that of impregnation-reduction method. In the nanoparticulate colloidal impregnation method, palladium nanoparticles were presynthesized, higher loading of Pd(0) could be obtained, resulting in better catalytic activity. The as-prepared Pd-loaded ceramic membrane support could be easily reused for several cycles without appreciable degradation of catalytic activity.

Characteristics of Iron-Palladium alloy thin films deposited by magnetron sputtering

Science.gov (United States)

Chiu, Y.-J.; Shen, C.-Y.; Chang, H.-W.; Jian, S.-R.

2018-06-01

The microstructural features, magnetic, nanomechanical properties and wettability behaviors of Iron-Palladium (FePd) alloy thin films are investigated by using X-ray diffraction (XRD), atomic force microscopy (AFM), vibrating sample magnetometer (VSM), nanoindentation and water contact angle (CA) techniques, respectively. The FePd alloy thin films were deposited on glass substrates using a magnetron sputtering system. The post-annealing processes of FePd alloy thin films were carried out at 400 °C and 750 °C and resulted in a significant increase of both the average grain size and surface roughness. The XRD analysis showed that FePd alloy thin films exhibited a predominant (1 1 1) orientation. The magnetic field dependence of magnetization of all FePd thin films are measured at room temperature showed the ferromagnetic characteristics. The nanoindentation with continuous stiffness measurement (CSM) is used to measure the hardness and Young's modulus of present films. The contact angle (θCA) increased with increasing surface roughness. The maximum θCA of 75° was achieved for the FePd alloy thin film after annealing at 750 °C and a surface roughness of 4.2 nm.

Test of the palladium diffuser in the JAERI Fuel Cleanup System in the Tritium Systems Test Assembly

International Nuclear Information System (INIS)

Konishi, Satoshi; Hayashi, Takumi; O-hira, Shigeru

1993-03-01

The JAERI Fuel Cleanup System (JFCU) is a major subsystem of the TSTA simulated fusion fuel loop. The palladium diffuser, that accepts simulated plasma exhaust and purifies the hydrogen isotopes mixture for the feed to the Isotope Separation System, was tested with deuterium to investigate the characteristics of the components. Permeation flow rate is a linear function of the difference of the square root of the pressure across the palladium alloy membrane. However at the low pressure region, an impediment on the permeation was observed. It was suspected to be caused by the impurity adsorbed on the surface of the permeated side of the membrane and was reduced by oxidation treatment. (author)

Cloud point extraction of palladium in water samples and alloy mixtures using new synthesized reagent with flame atomic absorption spectrometry (FAAS)

International Nuclear Information System (INIS)

Priya, B. Krishna; Subrahmanayam, P.; Suvardhan, K.; Kumar, K. Suresh; Rekha, D.; Rao, A. Venkata; Rao, G.C.; Chiranjeevi, P.

2007-01-01

The present paper outlines novel, simple and sensitive method for the determination of palladium by flame atomic absorption spectrometry (FAAS) after separation and preconcentration by cloud point extraction (CPE). The cloud point methodology was successfully applied for palladium determination by using new reagent 4-(2-naphthalenyl)thiozol-2yl azo chromotropic acid (NTACA) and hydrophobic ligand Triton X-114 as chelating agent and nonionic surfactant respectively in the water samples and alloys. The following parameters such as pH, concentration of the reagent and Triton X-114, equilibrating temperature and centrifuging time were evaluated and optimized to enhance the sensitivity and extraction efficiency of the proposed method. The preconcentration factor was found to be (50-fold) for 250 ml of water sample. Under optimum condition the detection limit was found as 0.067 ng ml -1 for palladium in various environmental matrices. The present method was applied for the determination of palladium in various water samples, alloys and the result shows good agreement with reported method and the recoveries are in the range of 96.7-99.4%

Sensitization to palladium and nickel in Europe and the relationship with oral disease and dental alloys

NARCIS (Netherlands)

Muris, J.; Goossens, A.; Gonçalo, M.; Bircher, A.J.; Giménez-Arnau, A.; Foti, C.; Rustemeyer, T.; Feilzer, A.J.; Kleverlaan, C.J.

2015-01-01

Background The role of palladium and nickel sensitization in oral disease and dermatitis is not fully understood. Objectives To investigate whether sensitization to these metals was associated with exposure to dental alloys and oral and skin complaints/symptoms in a European multicentre study.

ALTERNATIVE MATERIALS TO PD MEMBRANES FOR HYDROGEN PURIFICATION

Energy Technology Data Exchange (ETDEWEB)

Korinko, P; T. Adams

2008-09-12

Development of advanced hydrogen separation membranes in support of hydrogen production processes such as coal gasification and as front end gas purifiers for fuel cell based system is paramount to the successful implementation of a national hydrogen economy. Current generation metallic hydrogen separation membranes are based on Pd-alloys. Although the technology has proven successful, at issue is the high cost of palladium. Evaluation of non-noble metal based dense metallic separation membranes is currently receiving national and international attention. The focal point of the reported work was to evaluate two different classes of materials for potential replacement of conventional Pd-alloy purification/diffuser membranes. Crystalline V-Ni-Ti and Amorphous Fe- and Co-based metallic glass alloys have been evaluated using gaseous hydrogen permeation testing techniques.

Improving carbon tolerance of Ni-YSZ catalytic porous membrane by palladium addition for low temperature steam methane reforming

Science.gov (United States)

Lee, Sang Moon; Won, Jong Min; Kim, Geo Jong; Lee, Seung Hyun; Kim, Sung Su; Hong, Sung Chang

2017-10-01

Palladium was added on the Ni-YSZ catalytic porous membrane by wet impregnation and electroless plating methods. Its surface morphology characteristics and carbon deposition properties for the low temperature steam methane reforming were investigated. The addition of palladium could obviously be enhanced the catalytic activity as well as carbon tolerance of the Ni-YSZ porous membrane. The porous membranes were evaluated by scanning electron microscopy (SEM), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), H2 temperature-programmed reduction (H2-TPR), CH4 temperature-programmed reduction (CH4-TPR), and O2 temperature-programmed oxidation (O2-TPO). It was found that the Pd-Ni-YSZ catalytic porous membrane showed the superior stability as well as the deposition of carbon on the surface during carbon dissociation adsorption at 650 °C was also suppressed.

Palladium allergy in relation to dentistry

NARCIS (Netherlands)

Muris, J.

2015-01-01

Palladium is a metal that is used as alloying metal for dental crowns and bridges. This thesis focusses on the possible impact of oral exposure to this metal on the immune system, and allergy in particular. An alternative skin test allergen for diagnosing palladium allergy is introduced: (di)sodium

PALLADIUM/COPPER ALLOY COMPOSITE MEMBRANES FOR HIGH TEMPERATURE HYDROGEN SEPARATION FROM COAL-DERIVED GAS STREAMS; F

International Nuclear Information System (INIS)

J. Douglas Way; Robert L. McCormick

2001-01-01

Recent advances have shown that Pd-Cu composite membranes are not susceptible to the mechanical, embrittlement, and poisoning problems that have prevented widespread industrial use of Pd for high temperature H(sub 2) separation. These membranes consist of a thin ((approx)10(micro)m) film of metal deposited on the inner surface of a porous metal or ceramic tube. Based on preliminary results, thin Pd(sub 60)Cu(sub 40) films are expected to exhibit hydrogen flux up to ten times larger than commercial polymer membranes for H(sub 2) separation, and resist poisoning by H(sub 2)S and other sulfur compounds typical of coal gas. Similar Pd-membranes have been operated at temperatures as high as 750 C. The overall objective of the proposed project is to demonstrate the feasibility of using sequential electroless plating to fabricate Pd(sub 60)Cu(sub 40) alloy membranes on porous supports for H(sub 2) separation. These following advantages of these membranes for processing of coal-derived gas will be demonstrated: High H(sub 2) flux; Sulfur tolerant, even at very high total sulfur levels (1000 ppm); Operation at temperatures well above 500 C; and Resistance to embrittlement and degradation by thermal cycling. The proposed research plan is designed to providing a fundamental understanding of: Factors important in membrane fabrication; Optimization of membrane structure and composition; Effect of temperature, pressure, and gas composition on H(sub 2) flux and membrane selectivity; and How this membrane technology can be integrated in coal gasification-fuel cell systems

Ab initio study of the structural, magnetic, and electronic properties of copper and silver clusters and their alloys with one palladium atom

Directory of Open Access Journals (Sweden)

S. J Hashemifar

2015-01-01

Full Text Available In this paper, the structural, magnetic, and electronic properties of two- to nine-atom copper and silver clusters and their alloys with one palladium atom are investigated by using full-potential all-electron density functional computations. After calculating minimized energy of several structural isomers of every nanocluster, it is argued that the small size nanoclusters (up to size of 6, ‎ prefer planar structures, while by increasing size a 2D-3D structural transformation is observed. The structural transformation of pure and copper-palladium clusters occurs in the size of seven and that of silver-palladium cluster in happens at the size of six. The calculated second difference and dissociation energies confirm that the two- and eight- atom pure clusters and three- and seven- atom alloyed clusters are magic clusters. The electronic and magnetic properties of stable isomers are calculated and considered after applying many body based GW correction.

Monodisperse gold-palladium alloy nanoparticles and their composition-controlled catalysis in formic acid dehydrogenation under mild conditions.

Science.gov (United States)

Metin, Önder; Sun, Xiaolian; Sun, Shouheng

2013-02-07

Monodisperse 4 nm AuPd alloy nanoparticles with controlled composition were synthesized by co-reduction of hydrogen tetrachloroaurate(III) hydrate and palladium(II) acetylacetonate with a borane-morpholine complex in oleylamine. These NPs showed high activity (TOF = 230 h(-1)) and stability in catalyzing formic acid dehydrogenation and hydrogen production in water at 50 °C without any additives.

Testing of a 7-tube palladium membrane reactor for potential use in TEP

International Nuclear Information System (INIS)

Carlson, Bryan J.; Trujillo, Stephen; Willms, R. Scott

2010-01-01

A Palladium Membrane Reactor (PMR) consists of a palladium/silver membrane permeator filled with catalyst (catalyst may be inside or outside the membrane tubes). The PMR is designed to recover tritium from the methane, water, and other impurities present in fusion reactor effluent. A key feature of a PMR is that the total hydrogen isotope content of a stream is significantly reduced as (1) methane-steam reforming and/or water-gas shift reactions proceed on the catalyst bed and (2) hydrogen isotopes are removed via permeation through the membrane. With a PMR design matched to processing requirements, nearly complete hydrogen isotope removals can be achieved. A 3-tube PMR study was recently completed. From the results presented in this study, it was possible to conclude that a PMR is appropriate for TEP, perforated metal tube protectors function well, platinum on aluminum (PtA) catalyst performs the best, conditioning with air is probably required to properly condition the Pd/Ag tubes, and that CO/CO 2 ratios maybe an indicator of coking. The 3-tube PMR had a permeator membrane area of 0.0247 m 2 and a catalyst volume to membrane area ratio of 4.63 cc/cm 2 (with the catalyst on the outside of the membrane tubes and the catalyst only covering the membrane tube length). A PMR for TEP will require a larger membrane area (perhaps 0.35 m 2 ). With this in mind, an intermediate sized PMR was constructed. This PMR has 7 permeator tubes and a total membrane area of 0.0851 m 2 . The catalyst volume to membrane area ratio for the 7-tube PMR was 5.18 cc/cm 2 . The total membrane area of the 7-tube PMR (0.0851 m 2 ) is 3.45 times larger than total membrane area of the 3-tube PMR (0.0247 m 2 ). The following objectives were identified for the 7-tube PMR tests: (1) Refine test measurements, especially humidity and flow; (2) Refine maintenance procedures for Pd/Ag tube conditioning; (3) Evaluate baseline PMR operating conditions; (4) Determine PMR scaling method; (5) Evaluate PMR

Noble metal alloys for metal-ceramic restorations.

Science.gov (United States)

Anusavice, K J

1985-10-01

A review of the comparative characteristics and properties of noble metal alloys used for metal-ceramic restorations has been presented. Selection of an alloy for one's practice should be based on long-term clinical data, physical properties, esthetic potential, and laboratory data on metal-ceramic bond strength and thermal compatibility with commercial dental porcelains. Although gold-based alloys, such as the Au-Pt-Pd, Au-Pd-Ag, and Au-Pd classes, may appear to be costly compared with the palladium-based alloys, they have clearly established their clinical integrity and acceptability over an extended period of time. Other than the relatively low sag resistance of the high gold-low silver content alloys and the potential thermal incompatibility with some commercial porcelain products, few clinical failures have been observed. The palladium-based alloys are less costly than the gold-based alloys. Palladium-silver alloys require extra precautions to minimize porcelain discoloration. Palladium-copper and palladium-cobalt alloys may also cause porcelain discoloration, as copper and cobalt are used as colorants in glasses. The palladium-cobalt alloys are least susceptible to high-temperature creep compared with all classes of noble metals. Nevertheless, insufficient clinical data exist to advocate the general use of the palladium-copper and palladium-cobalt alloys at the present time. One should base the selection and use of these alloys in part on their ability to meet the requirements of the ADA Acceptance Program. A list of acceptable or provisionally acceptable alloys is available from the American Dental Association and is published annually in the Journal of the American Dental Association. Dentists have the legal and ethical responsibility for selection of alloys used for cast restorations. This responsibility should not be delegated to the dental laboratory technician. It is advisable to discuss the criteria for selection of an alloy with the technician and the

Potentiodynamic polarization study of the corrosion behavior of palladium-silver dental alloys.

Science.gov (United States)

Sun, Desheng; Brantley, William A; Frankel, Gerald S; Heshmati, Reza H; Johnston, William M

2018-04-01

Although palladium-silver alloys have been marketed for over 3 decades for metal-ceramic restorations, understanding of the corrosion behavior of current alloys is incomplete; this understanding is critical for evaluating biocompatibility and clinical performance. The purpose of this in vitro study was to characterize the corrosion behavior of 3 representative Pd-Ag alloys in simulated body fluid and oral environments and to compare them with a high-noble Au-Pd alloy. The study obtained values of important electrochemical corrosion parameters, with clinical relevance, for the rational selection of casting alloys. The room temperature in vitro corrosion characteristics of the 3 Pd-Ag alloys and the high-noble Au-Pd alloy were evaluated in 0.9% NaCl, 0.09% NaCl, and Fusayama solutions. After simulated porcelain firing heat treatment, 5 specimens of each alloy were immersed in the electrolytes for 24 hours. For each specimen, the open-circuit potential (OCP) was first recorded, and linear polarization was then performed from -20 mV to +20 mV (versus OCP) at a rate of 0.125 mV/s. Cyclic polarization was subsequently performed on 3 specimens of each alloy from -300 mV to +1000 mV and back to -300 mV (versus OCP) at a scanning rate of 1 mV/s. The differences in OCP and corrosion resistance parameters (zero-current potential and polarization resistance) among alloys and electrolyte combinations were compared with the 2-factor ANOVA (maximum-likelihood method) with post hoc Tukey adjustments (α=.05). The 24-hour OCPs and polarization resistance values of the 3 Pd-Ag alloys and the Au-Pd alloy were not significantly different (P=.233 and P=.211, respectively) for the same electrolyte, but significant differences were found for corrosion test results in different electrolytes (Palloy and electrolyte (P=.249 and P=.713, respectively). The 3 Pd-Ag silver alloys appeared to be resistant to chloride ion corrosion, and passivation and de-alloying were identified for these

Recent palladium membrane reactor development at the tritium systems test assembly

International Nuclear Information System (INIS)

Willms, R.S.; Birdsell, S.A.; Wilhelm, R.C.

1995-01-01

The palladium membrane reactor (PMR) is proving to be a simple and effective means for recovering hydrogen isotopes from fusion fuel impurities such as methane and water. This device directly combines two techniques which have long been utilized for hydrogen processing, namely catalytic shift reactions and palladium/silver permeators. A proof-of-principle (PMR) has been constructed and tested at the Tritium Systems Test Assembly of Los Alamos National Laboratory. The first tests with this device showed that is was effective for the proposed purpose. Initial work concluded that a nickel catalyst was an appropriate choice for use in a PMR. More detailed testing of the PMR with such a catalyst was performed and reported in other works. It was shown that a nickel catalyst-packed PMR did, indeed, recover hydrogen from water and methane with efficiencies approaching 100% in a single processing pass. These experiments were conducted over an extended period of time and no failure or need for regeneration was encountered. These positive results have prompted further PMR development. Topics addressed include alternate PMR geometries and initial testing of the PMR with tritium. These are the subjects of this paper

Engineering Defect-Free Nanoporous Pd from Optimized Pd-Ni Precursor Alloy by Understanding Palladium-Hydrogen Interactions During Dealloying

Science.gov (United States)

Schoop, Julius; Balk, T. John

2014-04-01

Thin films of nanoporous palladium (np-Pd) were produced from binary palladium-nickel (Pd-Ni) precursor alloys. A suitable precursor alloy and a method of dealloying to yield optimum nanoporosity (average pore/ligament size of 7 nm) were developed by studying the effects of various processing parameters on final microstructure. To obtain crack-free np-Pd, a 100 nm thin film of 20 at. pct Pd (80 at. pct Ni) can be dealloyed for ~5 hours in a 1 M solution of sulfuric acid, with oleic acid and oleylamine added as surfactants. Both shorter and longer dealloying times, as well as heating, inhibit the formation of crack-free np-Pd. Stress measurements at different stages of dealloying revealed that the necessary dealloying time is determined by the diffusion-controlled corrosion reaction occurring within the thin film during dealloying. Strong interaction between hydrogen and np-Pd was reflected in the stress evolution during dealloying. A mechanism is proposed for the formation of a Ni-rich dense top layer that results from H-induced swelling during initial dealloying and permits the development of defect-free np-Pd beneath, by limiting the speed of dealloying.

Palladium-alloy catalysts as ethanol tolerant cathodes for direct alcohol fuel cell applications

Energy Technology Data Exchange (ETDEWEB)

Savadogo, O. [Ecole Polytechnique de Montreal, Montreal, PQ (Canada). Laboratoire de nouveaux materiaux pour l' energie et l' electrochimie; Varela, F.J.R. [Centro de Investigacion y de Estudios Avanzados, Coahuila (Mexico). Unidad Saltillo

2008-07-01

Recent studies have demonstrated that electroactive palladium (Pd) and Pd-alloy catalysts prepared using a sputtering technique possess a similar degree of activity as platinum (Pt) electrodes. This study demonstrated that Pd and Pd-alloys show a high degree of tolerance to ethanol during oxygen reduction reaction (ORR) processes. The onset potential of the ORR process in the presence of 0.5M of ethanol decreased by only 33 mV and 18 mV on Pd and Pd-cobalt (Co) catalysts. Linear sweep voltammetry experiments showed that no peak current density caused by the electro-oxidation of ethanol was observed in the Pd-based catalysts. The selective behaviour of the Pd and Pd-Co catalysts was attributed to a slow rate of adsorption of the ethanol as well as the presence of reaction intermediates on the catalytic surface. Results suggested that the Pd and Pd-Co catalysts are suitable candidates for direct alcohol fuel cell applications. 10 refs., 2 figs.

Conversion of hydrophilic SiOC nanofibrous membrane to robust hydrophobic materials by introducing palladium

Science.gov (United States)

Wu, Nan; Wan, Lynn Yuqin; Wang, Yingde; Ko, Frank

2017-12-01

Hydrophobic ceramic nanofibrous membranes have wide applications in the fields of high-temperature filters, oil/water separators, catalyst supports and membrane reactors, for their water repellency property, self-cleaning capability, good environmental stability and long life span. In this work, we fabricated an inherently hydrophobic ceramic nanofiber membrane without any surface modification through pyrolysis of electrospun polycarbosilane nanofibers. The hydrophobicity was introduced by the hierarchical microstructure formed on the surface of the nanofibers and the special surface composition by the addition of trace amounts of palladium. Furthermore, the flexible ceramic mats demonstrated robust chemical resistance properties with consistent hydrophobicity over the entire pH value range and effective water-in-oil emulsion separation performance. Interestingly, a highly cohesive force was found between water droplet and the ceramic membranes, suggesting their great potentials in micro-liquid transportation. This work provides a new route for adjusting the composition of ceramic surface and flexible, recyclable and multifunctional ceramic fibrous membranes for utilization in harsh environments.

MONTANA PALLADIUM RESEARCH INITIATIVE

Energy Technology Data Exchange (ETDEWEB)

Peters, John; McCloskey, Jay; Douglas, Trevor; Young, Mark; Snyder, Stuart; Gurney, Brian

2012-05-09

Project Objective: The overarching objective of the Montana Palladium Research Initiative is to perform scientific research on the properties and uses of palladium in the context of the U.S. Department of Energy's Hydrogen, Fuel Cells and Infrastructure Technologies Program. The purpose of the research will be to explore possible palladium as an alternative to platinum in hydrogen-economy applications. To achieve this objective, the Initiatives activities will focus on several cutting-edge research approaches across a range of disciplines, including metallurgy, biomimetics, instrumentation development, and systems analysis. Background: Platinum-group elements (PGEs) play significant roles in processing hydrogen, an element that shows high potential to address this need in the U.S. and the world for inexpensive, reliable, clean energy. Platinum, however, is a very expensive component of current and planned systems, so less-expensive alternatives that have similar physical properties are being sought. To this end, several tasks have been defined under the rubric of the Montana Palladium Research Iniative. This broad swath of activities will allow progress on several fronts. The membrane-related activities of Task 1 employs state-of-the-art and leading-edge technologies to develop new, ceramic-substrate metallic membranes for the production of high-purity hydrogen, and develop techniques for the production of thin, defect-free platinum group element catalytic membranes for energy production and pollution control. The biomimetic work in Task 2 explores the use of substrate-attached hydrogen-producing enzymes and the encapsulation of palladium in virion-based protein coats to determine their utility for distributed hydrogen production. Task 3 work involves developing laser-induced breakdown spectroscopy (LIBS) as a real-time, in situ diagnostic technique to characterize PGEs nanoparticles for process monitoring and control. The systems engineering work in task 4

Platinum and Palladium Alloys Suitable as Fuel Cell Electrodes

DEFF Research Database (Denmark)

2011-01-01

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...... 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...

Development of Separation Materials Containing Palladium for Hydrogen Isotopes Separation

International Nuclear Information System (INIS)

Deng Xiaojun; Luo Deli; Qian Xiaojing

2010-01-01

Displacement chromatography (DC) is a ascendant technique for hydrogen isotopes separation. The performance of separation materials is a key factor to determine the separation effect of DC. At present,kinds of materials are researched, including palladium materials and non-palladium materials. It is hardly replaceable because of its excellent separation performance, although palladium is expensive. The theory of hydrogen isotopes separation using DC was introduced at a brief manner, while several palladium separation materials were expatiated in detail(Pd/K, Pd-Al 2 O 3 , Pd-Pt alloy). Development direction of separation materials for DC was forecasted elementarily. (authors)

Catalytic membrane reactors for tritium recovery from tritiated water in the ITER fuel cycle

International Nuclear Information System (INIS)

Tosti, S.; Violante, V.; Basile, A.; Chiappetta, G.; Castelli, S.; De Francesco, M.; Scaglione, S.; Sarto, F.

2000-01-01

Palladium and palladium-silver permeators have been obtained by coating porous ceramic tubes with a thin metal layer. Three coating techniques have been studied and characterized: chemical electroless deposition (PdAg film thickness of 10 μm), ion sputtering (about 1 μm) and rolling of thin metal sheets (50 μm). The Pd-ceramic membranes have been used for manufacturing catalytic membrane reactors (CMR) for hydrogen and its isotopes recovering and purifying. These composite membranes and the CMR have been studied and developed for a closed-loop process with reference to the design requirements of the international thermonuclear experimental reactor (ITER) blanket tritium recovery system in the enhanced performance phase of operation. The membranes and CMR have been tested in a pilot plant equipped with temperature, pressure and flow-rate on-line measuring and controlling devices. The conversion value for the water gas shift reaction in the CMR has been measured close to 100% (always above the equilibrium one, 80% at 350 deg. C): the effect of the membrane is very clear since the reaction is moved towards the products because of the continuous hydrogen separation. The rolled thin film membranes have separated the hydrogen from other gases with a complete selectivity and exhibited a slightly larger mass transfer resistance with respect to the electroless membranes. Preliminary tests on the sputtered membranes have also been carried out with a promising performance. Considerations on the use of different palladium alloy in order to improve the performances of the membranes in terms of permeation flux and mechanical strength, such as palladium/yttrium, are also reported

Advanced Palladium Membrane Scale-up for Hydrogen Separation

Energy Technology Data Exchange (ETDEWEB)

Emerson, Sean; Magdefrau, Neal; She, Ying; Thibaud-Erkey, Catherine

2012-10-31

and ex situ (laboratory) air regeneration at 450 °C could restore separator performance by burning out such deposits. Gasifier testing revealed that high molecular weight hydrocarbons have the potential to retard H2 separation. Unconverted coal tars with carbon numbers greater than 14 have a boiling point such that they can act as a reversible poison to the Pd-Cu membranes even at temperatures above 500 °C. The use of real-time, physics-based, performance models revealed the effect of these coal tars. It is believed that this project provided the first evidence for the impact of coal tars on H{sub 2} separator performance. Final down-selection of candidate alloys for non-membrane materials of construction proceeded by evaluating the alloys in both UTRC laboratory tests and testing downstream of an actual gasifier at the National Carbon Capture Center (NCCC). The overall alloy ratings were calculated by multiplying the projected cost of a 100 lb day{sup -1} H{sub 2} separator outer shell by the projected oxide scale thickness for 5 years of operation. The alloy with the lowest resulting rating parameter was stainless steel 309 (SS-309) followed by stainless steel 310 (SS-310). However, it was noted that approximately half of the alloys showed susceptibility to pitting and localized corrosion. SS-309 was one of the alloys that exhibited heavy localized attack after 2000 hours of laboratory testing. As this localized corrosion can potentially lead to accelerated end of life, it was determined that SS-310 would be the best alloy selection for this application as it does not show signs of localized pitting corrosion.

Pilot Scale Water Gas Shift - Membrane Device for Hydrogen from Coal

Energy Technology Data Exchange (ETDEWEB)

Barton, Tom [Western Research Inst. (WRI), Laramie, WY (United States)

2013-09-01

The objectives of the project were to build pilot scale hydrogen separation systems for use in a gasification product stream. This device would demonstrate fabrication and manufacturing techniques for producing commercially ready facilities. The design was a 2 lb/day hydrogen device which included composite hydrogen separation membranes, a water gas shift monolith catalyst, and stainless steel structural components. Synkera Technologies was to prepare hydrogen separation membranes with metallic rims, and to adjust the alloy composition in their membranes to a palladium-gold composition which is sulfur resistant. Chart was to confirm their brazing technology for bonding the metallic rims of the composite membranes to their structural components and design and build the 2 lbs/day device incorporating membranes and catalysts. WRI prepared the catalysts and completed the testing of the membranes and devices on coal derived syngas. The reactor incorporated eighteen 2'' by 7'' composite palladium alloy membranes. These membranes were assembled with three stacks of three paired membranes. Initial vacuum testing and visual inspection indicated that some membranes were cracked, either in transportation or in testing. During replacement of the failed membranes, while pulling a vacuum on the back side of the membranes, folds were formed in the flexible composite membranes. In some instances these folds led to cracks, primarily at the interface between the alumina and the aluminum rim. The design of the 2 lb/day device was compromised by the lack of any membrane isolation. A leak in any membrane failed the entire device. A large number of tests were undertaken to bring the full 2 lb per day hydrogen capacity on line, but no single test lasted more than 48 hours. Subsequent tests to replace the mechanical seals with brazing have been promising, but the technology remains promising but not proven.

Processing Tritiated Water at the Savannah River Site: A Production-Scale Demonstration of a palladium membrane reactor

International Nuclear Information System (INIS)

Sessions, K

2004-01-01

The Palladium Membrane Reactor (PMR) process was installed in the Tritium Facilities at the Savannah River Site to perform a production-scale demonstration for the recovery of tritium from tritiated water adsorbed on molecular sieve (zeolite). Unlike the current recovery process that utilizes magnesium, the PMR offers a means to process tritiated water in a more cost effective and environmentally friendly manner. The design and installation of the large-scale PMR process was part of a collaborative effort between the Savannah River Site and Los Alamos National Laboratory. The PMR process operated at the Savannah River Site between May 2001 and April 2003. During the initial phase of operation the PMR processed thirty-four kilograms of tritiated water from the Princeton Plasma Physics Laboratory. The water was processed in fifteen separate batches to yield approximately 34,400 liters (STP) of hydrogen isotopes. Each batch consisted of round-the-clock operations for approximately nine days. In April 2003 the reactor's palladium-silver membrane ruptured resulting in the shutdown of the PMR process. Reactor performance, process performance and operating experiences have been evaluated and documented. A performance comparison between PMR and current magnesium process is also documented

Recent palladium membrane reactor development at the tritium systems test assembly

International Nuclear Information System (INIS)

Scott, W.R.; Birdsell, S.A.; Wilhelm, R.C.

1995-01-01

The palladium membrane reactor (PMR) is being investigated as a means for recovering hydrogen isotopes (including tritium) from compounds such as water and methane. Previous work with protiated water and methane showed that this device can be used to obtain high hydrogen recovery efficiencies using a single processing pass and with essentially no waste production. With these successful proof-of-principle results completed, recent work has focused on PMR development. This included studies of various geometries and testing with tritium. The results, which are reported here, have led to a better understanding of the PMR and will lead to the ultimate goal of building a production PMR and putting it into practical tritium processing service. 3 refs., 5 figs., 1 tab

Review of Supported Pd-Based Membranes Preparation by Electroless Plating for Ultra-Pure Hydrogen Production.

Science.gov (United States)

Alique, David; Martinez-Diaz, David; Sanz, Raul; Calles, Jose A

2018-01-23

In the last years, hydrogen has been considered as a promising energy vector for the oncoming modification of the current energy sector, mainly based on fossil fuels. Hydrogen can be produced from water with no significant pollutant emissions but in the nearest future its production from different hydrocarbon raw materials by thermochemical processes seems to be more feasible. In any case, a mixture of gaseous compounds containing hydrogen is produced, so a further purification step is needed to purify the hydrogen up to required levels accordingly to the final application, i.e., PEM fuel cells. In this mean, membrane technology is one of the available separation options, providing an efficient solution at reasonable cost. Particularly, dense palladium-based membranes have been proposed as an ideal chance in hydrogen purification due to the nearly complete hydrogen selectivity (ideally 100%), high thermal stability and mechanical resistance. Moreover, these membranes can be used in a membrane reactor, offering the possibility to combine both the chemical reaction for hydrogen production and the purification step in a unique device. There are many papers in the literature regarding the preparation of Pd-based membranes, trying to improve the properties of these materials in terms of permeability, thermal and mechanical resistance, poisoning and cost-efficiency. In this review, the most relevant advances in the preparation of supported Pd-based membranes for hydrogen production in recent years are presented. The work is mainly focused in the incorporation of the hydrogen selective layer (palladium or palladium-based alloy) by the electroless plating, since it is one of the most promising alternatives for a real industrial application of these membranes. The information is organized in different sections including: (i) a general introduction; (ii) raw commercial and modified membrane supports; (iii) metal deposition insights by electroless-plating; (iv) trends in

Designing and Validating Ternary Pd Alloys for Optimum Sulfur/Carbon Resistance in Hydrogen Separation and Carbon Capture Membrane Systems Using High-Throughput Combinatorial Methods

Energy Technology Data Exchange (ETDEWEB)

Lewis, Amanda [Pall Corporation, Port Washington, NY (United States); Zhao, Hongbin [Pall Corporation, Port Washington, NY (United States); Hopkins, Scott [Pall Corporation, Port Washington, NY (United States)

2014-12-01

This report summarizes the work completed under the U.S. Department of Energy Project Award No.: DE-FE0001181 titled “Designing and Validating Ternary Pd Alloys for Optimum Sulfur/Carbon Resistance in Hydrogen Separation and Carbon Capture Membrane Systems Using High-Throughput Combinatorial Methods.” The project started in October 1, 2009 and was finished September 30, 2014. Pall Corporation worked with Cornell University to sputter and test palladium-based ternary alloys onto silicon wafers to examine many alloys at once. With the specialized equipment at Georgia Institute of Technology that analyzed the wafers for adsorbed carbon and sulfur species six compositions were identified to have resistance to carbon and sulfur species. These compositions were deposited on Pall AccuSep® supports by Colorado School of Mines and then tested in simulated synthetic coal gas at the Pall Corporation. Two of the six alloys were chosen for further investigations based on their performance. Alloy reproducibility and long-term testing of PdAuAg and PdZrAu provided insight to the ability to manufacture these compositions for testing. PdAuAg is the most promising alloy found in this work based on the fabrication reproducibility and resistance to carbon and sulfur. Although PdZrAu had great initial resistance to carbon and sulfur species, the alloy composition has a very narrow range that hindered testing reproducibility.

Effects of soldering methods on tensile strength of a gold-palladium metal ceramic alloy.

Science.gov (United States)

Ghadhanfari, Husain A; Khajah, Hasan M; Monaco, Edward A; Kim, Hyeongil

2014-10-01

The tensile strength obtained by conventional postceramic application soldering and laser postceramic welding may require more energy than microwave postceramic soldering, which could provide similar tensile strength values. The purpose of the study was to compare the tensile strength obtained by microwave postceramic soldering, conventional postceramic soldering, and laser postceramic welding. A gold-palladium metal ceramic alloy and gold-based solder were used in this study. Twenty-seven wax specimens were cast in gold-palladium noble metal and divided into 4 groups: laser welding with a specific postfiller noble metal, microwave soldering with a postceramic solder, conventional soldering with the same postceramic solder used in the microwave soldering group, and a nonsectioned control group. All the specimens were heat treated to simulate a normal porcelain sintering sequence. An Instron Universal Testing Machine was used to measure the tensile strength for the 4 groups. The means were analyzed statistically with 1-way ANOVA. The surface and fracture sites of the specimens were subjectively evaluated for fracture type and porosities by using a scanning electron microscope. The mean (standard deviation) ultimate tensile strength values were as follows: nonsectioned control 818 ±30 MPa, microwave 516 ±34 MPa, conventional 454 ±37 MPa, and laser weld 191 ±39 MPa. A 1-way ANOVA showed a significant difference in ultimate tensile strength among the groups (F3,23=334.5; Ptensile strength for gold and palladium noble metals than either conventional soldering or laser welding. Conventional soldering resulted in a higher tensile strength than laser welding. Under the experimental conditions described, either microwave or conventional postceramic soldering would appear to satisfy clinical requirements related to tensile strength. Copyright © 2014 Editorial Council for the Journal of Prosthetic Dentistry. Published by Elsevier Inc. All rights reserved.

Polymer and Membrane Design for Low Temperature Catalytic Reactions

KAUST Repository

Villalobos, Luis Francisco

2016-02-29

Catalytically active asymmetric membranes have been developed with high loadings of palladium nanoparticles located solely in the membrane\\'s ultrathin skin layer. The manufacturing of these membranes requires polymers with functional groups, which can form insoluble complexes with palladium ions. Three polymers have been synthesized for this purpose and a complexation/nonsolvent induced phase separation followed by a palladium reduction step is carried out to prepare such membranes. Parameters to optimize the skin layer thickness and porosity, the palladium loading in this layer, and the palladium nanoparticles size are determined. The catalytic activity of the membranes is verified with the reduction of a nitro-compound and with a liquid phase Suzuki-Miyaura coupling reaction. Very low reaction times are observed. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Antibiofilm effect enhanced by modification of 1,2,3-triazole and palladium nanoparticles on polysulfone membranes

KAUST Repository

Cheng, Hong; Xie, Yihui; Villalobos, Luis Francisco; Song, Liyan; Peinemann, Klaus-Viktor; Nunes, Suzana Pereira; Hong, Pei-Ying

2016-01-01

Biofouling impedes the performance of membrane bioreactors. In this study, we investigated the antifouling effects of polysulfone membranes that were modified by 1,2,3-triazole and palladium (Pd) nanoparticles. The modified membranes were evaluated for antibacterial and antifouling efficacy in a monoculture species biofilm (i.e., drip flow biofilm reactor, DFR) and mixed species biofilm experiment (i.e., aerobic membrane reactor, AeMBR). 1,2,3-triazole and Pd nanoparticles inhibited growth of Pseudomonas aeruginosa in both aerobic and anaerobic conditions. The decrease in bacterial growth was observed along with a decrease in the amount of total polysaccharide within the monoculture species biofilm matrix. When the modified membranes were connected to AeMBR, the increase in transmembrane pressure was lower than that of the non-modified membranes. This was accompanied by a decrease in protein and polysaccharide concentrations within the mixed species biofilm matrix. Biomass amount in the biofilm layer was also lower in the presence of modified membranes, and there was no detrimental effect on the performance of the reactor as evaluated from the nutrient removal rates. 16S rRNA analysis further attributed the delay in membrane fouling to the decrease in relative abundance of selected bacterial groups. These observations collectively point to a lower fouling occurrence achieved by the modified membranes.

Antibiofilm effect enhanced by modification of 1,2,3-triazole and palladium nanoparticles on polysulfone membranes

KAUST Repository

Cheng, Hong

2016-04-12

Biofouling impedes the performance of membrane bioreactors. In this study, we investigated the antifouling effects of polysulfone membranes that were modified by 1,2,3-triazole and palladium (Pd) nanoparticles. The modified membranes were evaluated for antibacterial and antifouling efficacy in a monoculture species biofilm (i.e., drip flow biofilm reactor, DFR) and mixed species biofilm experiment (i.e., aerobic membrane reactor, AeMBR). 1,2,3-triazole and Pd nanoparticles inhibited growth of Pseudomonas aeruginosa in both aerobic and anaerobic conditions. The decrease in bacterial growth was observed along with a decrease in the amount of total polysaccharide within the monoculture species biofilm matrix. When the modified membranes were connected to AeMBR, the increase in transmembrane pressure was lower than that of the non-modified membranes. This was accompanied by a decrease in protein and polysaccharide concentrations within the mixed species biofilm matrix. Biomass amount in the biofilm layer was also lower in the presence of modified membranes, and there was no detrimental effect on the performance of the reactor as evaluated from the nutrient removal rates. 16S rRNA analysis further attributed the delay in membrane fouling to the decrease in relative abundance of selected bacterial groups. These observations collectively point to a lower fouling occurrence achieved by the modified membranes.

Platinum and palladium alloys suitable as fuel cell electrodes

DEFF Research Database (Denmark)

2014-01-01

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...... and innovative catalyst compositions in fuel cell electrodes. The novel electrode catalysts of the invention comprise a noble metal selected from Pt and Pd alloyed with an alkaline earth metal....

Platinum and palladium alloys suitable as fuel cell electrodes

DEFF Research Database (Denmark)

2014-01-01

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 catalytic5 efficiency by low level substitution of the noble metal to provide new...... and innovative catalyst compositions in fuel cell electrodes. The novel electrode catalysts of the invention comprise a noble metal selected from Pt and Pd alloyed with a lanthanide metal....

Polymer and Membrane Design for Low Temperature Catalytic Reactions

KAUST Repository

Villalobos, Luis Francisco; Xie, Yihui; Nunes, Suzana Pereira; Peinemann, Klaus-Viktor

2016-01-01

Catalytically active asymmetric membranes have been developed with high loadings of palladium nanoparticles located solely in the membrane's ultrathin skin layer. The manufacturing of these membranes requires polymers with functional groups, which can form insoluble complexes with palladium ions. Three polymers have been synthesized for this purpose and a complexation/nonsolvent induced phase separation followed by a palladium reduction step is carried out to prepare such membranes. Parameters to optimize the skin layer thickness and porosity, the palladium loading in this layer, and the palladium nanoparticles size are determined. The catalytic activity of the membranes is verified with the reduction of a nitro-compound and with a liquid phase Suzuki-Miyaura coupling reaction. Very low reaction times are observed. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Mechanistic insight into oxide-promoted palladium catalysts for the electro-oxidation of ethanol.

Science.gov (United States)

Martinez, Ulises; Serov, Alexey; Padilla, Monica; Atanassov, Plamen

2014-08-01

Recent advancements in the development of alternatives to proton exchange membrane fuel cells utilizing less-expensive catalysts and renewable liquid fuels, such as alcohols, has been observed for alkaline fuel cell systems. Alcohol fuels present the advantage of not facing the challenge of storage and transportation encountered with hydrogen fuel. Oxidation of alcohols has been improved by the promotion of alloyed or secondary phases. Nevertheless, currently, there is no experimental understanding of the difference between an intrinsic and a synergistic promotion effect in high-pH environments. This report shows evidence of different types of promotion effects on palladium electrocatalysts obtained from the presence of an oxide phase for the oxidation of ethanol. The correlation of mechanistic in situ IR spectroscopic studies with electrochemical voltammetry studies on two similar electrocatalytic systems allow the role of either an alloyed or a secondary phase on the mechanism of oxidation of ethanol to be elucidated. Evidence is presented for the difference between an intrinsic effect obtained from an alloyed system and a synergistic effect produced by the presence of an oxide phase. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Micromachined Dense Palladium Electrodes for Thin-film Solid Acid Fuel Cells

NARCIS (Netherlands)

Unnikrishnan, S.

2009-01-01

This thesis paves the way towards the microfabrication of a solid acid electrolyte based fuel cell (µSAFC), which has a membrane electrode assembly (MEA) consisting of a thin-film of water soluble electrolyte encapsulated between two dense palladium electrode membranes. This project work

Development of inductively coupled plasma atomic emission spectrometry for palladium and Rhodium determination in platinum-based alloy

International Nuclear Information System (INIS)

Kovacevic, R.; Todorovic, M.; Manojlovic, D.; Mutic, J.

2008-01-01

Inductively coupled plasma atomic emission spectroscopy with internal standardization was applied for the analysis of an in-house reference platinum alloy containing palladium and rhodium (approximately 5% by weight). In order to compensate for variations in signal recovery due to matrix interferences, and therefore to improve the precision, platinum. the major component, was chosen as an internal standard. Quantitative analysis was based on calibration using a set of matrix-matched calibration standards with and without employing the internal standard. These results were compared with those obtained by X-ray fluorescence spectroscopy. The results for both techniques were in a good agreement, although the precision was slightly better in the inductively coupled plasma atomic emission spectroscopy technique, with or without the internal standard

Effect of inlet conditions on the performance of a palladium membrane reactor

International Nuclear Information System (INIS)

Birdsell, S.A.; Willms, R.S.; Arzu, P.; Costello, A.

1997-10-01

Palladium membrane reactors (PMR) will be used to remove tritium and other hydrogen isotopes from impurities, such as tritiated methane and tritiated water, in the exhaust of the International Thermonuclear Experimental Reactor. In addition to fusion-fuel processing, the PMR system can be used to recover tritium from tritiated waste water. This paper investigates the effect of inlet conditions on the performance of a PMR. A set of experiments were run to determine, independently, the effect of inlet compositions and residence time on performance. Also, the experiments were designed to determine if the injected form of hydrogen (CH 4 or H 2 O) effects performance. Results show that the PMR operates at optimal hydrogen recovery with a broad range of inlet compositions and performance is shown to increase with increased residence time. PMR performance is shown to be independent of whether hydrogen is injected in the form of CH 4 or H 2 O

Design study of fuel circulating system using Pd alloy membrane isotope separation method

International Nuclear Information System (INIS)

Naito, T.; Yamada, T.; Aizawa, T.; Kasahara, T.; Yamanaka, T.

1981-01-01

It is expected that the method of permeating through Pd-alloy membrances is effective for isotope separation and the refining of fuel gas. In this paper, the design study of the Fuel Circulating System (FCS) using Pb-alloy membranes is described. The study is mainly focused on the main vacuum, fuel gas refining, isotope separating, and tritium containment systems. In the fuel gas refining system, impurities are effectively removed by using Pd-alloy membranes. For the isotope separation system, the diffusion method through Pd-alloy membranes was adopted. From the standpoint of the safety and economy, a three-stage tritium containment system was adopted to control tritium release to the environment as low as possible. The principal conclusion drawn from the design study was as follows. In the FCS, while cryogenic distillation method appears to be practicable, Pd-alloy membrane method is attractive for isotope separation and the refining of fuel gas. For a large amount of tritium inventory, handling and control technologies should be completed by the experimental evaluation and development of the components and materials used for the FCS. A three-stage containment system was adopted to control tritium release to environment as low as possible. Consideration to prevent tritium escape will be necessary for fuel gas refiners and isotope separators. (Kato, T.)

Method for palladium activating molybdenum metallized features on a ceramic substrate

International Nuclear Information System (INIS)

Kumar, A.H.; Schwartz, B.

1985-01-01

A molybdenum or tungsten metallurgical pattern is formed on or in a dielectric green sheet. Palladium, nickel, platinum or rhodium is coated on a layer of polyvinyl butyral which is carried on a polyester film. The metal layer of this assembly is laminated to a dielectric green sheet which carries the molybdenum or tungsten metallurgy. The polyester film is stripped off. The resulting assembly is sintered to a fired structure, whereby the polyvinyl butyral is volatilized off and the palladium, nickel, platinum or rhodium is alloyed with the molybdenum or tungsten metallurgy to provide a densified metallurgy whose surface is free of glass

Performance of a palladium membrane reactor using a Ni catalyst for fusion fuel impurities processing

International Nuclear Information System (INIS)

Willms, R.S.; Wilhelm, R.; Okuno, K.

1994-01-01

The palladium membrane reactor (PNM) provides a means to recover hydrogen isotopes from impurities expected to be present in fusion reactor exhaust. This recovery is based on reactions such as water-gas shift and steam reforming for which conversion is equilibrium limited. By including a selectively permeable membrane such as Pd/Ag in the catalyst bed, hydrogen isotopes can be removed from the reacting environment, thus promoting the reaction to complete conversion. Such a device has been built and operated at the Tritium Systems Test Assembly (TSTA) at Los Alamos National Laboratory (LANL). For the reactions listed above, earlier study with this unit has shown that hydrogen single-pass recoveries approaching 100% can be achieved. It was also determined that a nickel catalyst is a feasible choice for use with a PMR appropriate for fusion fuel impurities processing. The purpose of this study was to systematically assess the performance of the PMR using a nickel catalyst over a range of temperatures, feed compositions and flowrates. Reactions which were studied are the water-gas shift reaction and steam reforming

Elaboration and characterisation of Pd-Cr alloys for PEM fuel cells

Energy Technology Data Exchange (ETDEWEB)

Souleymane, B.; Fouda-Onana, F.; Savadogo, O. [Ecole Polytechnique de Montreal, Montreal, PQ (Canada). Laboratoire de nouveaux materiaux pour l' energie et l' electrochimie

2008-07-01

Palladium (Pd) alloys have been considered as alternative catalyst cathodes for the oxygen reduction reaction (ORR) in proton exchange membrane (PEM) fuel cells, particularly in liquid fuel cells. The purpose of this study was to investigate the ORR on various Pd-Cr alloys. Pd-Cr alloys were deposited on glassy carbon support and the electrocatalytic parameters for the ORR were determined in acid medium. The effect of the Pd-Cr alloy deposition parameters on its composition and electrocatalytic behaviour were determined. The study showed that there is a relationship between the composition of the alloy and the power of the Pd and Cr cathode. The parameters of the ORR were correlated to the alloy chemical and physical properties. EDS and XPS analysis revealed a segregation of Cr in the alloy.The variation of the work function (W) of the alloy with the alloy composition has shown a minimum value of W of 0.287 for a composition of the alloy of 70 per cent of Pd and 30 per cent of Cr. The electrochemically active surface area and the exchange current density of the ORR indicated that the mechanism of the ORR on Pd-Cr is similar to that on platinum. 9 refs., 2 figs.

Measurement of in-vivo dosage increase due to dental alloys during therapeutic irradiation of the mouth cavity

International Nuclear Information System (INIS)

Thilmann, C.; Mose, S.; Saran, F.; Schopohl, B.; Boettcher, H.D.

1995-01-01

The degree of dosage increase in the immediate surrounding of metallic dental materials was measured in an in-vivo study during therapeutic irradiation with 60 Co gamma rays in the area of mouth cavity of 11 patients. Measurements were carried out by thermoluminescent dosimetry at permamently fixed golden teeth and alloy specimens containing gold and palladium and amalgam. The following relative dodage values according to a simultanelusly measured reference value were measured at the surface of the different dental materials: 161% near fixed golden caps, 168% near the specimen containing gold in a high percentage, 133% near the specimen of palladium and 161% near the specimen of amalgam. The in vivo measured dosage increases due to metallic dental prosthesis are less than values obtained using back scatter arramgements for irradiating phantoms. Despite this, they could be of clinical relevance. Thus the usage of a mucous membrane protection during irradiation with 60 Co, as a means of preventing local lesions of the oral mucosa, due to dental alloys within the treatment volume remains inevitable. (orig.) [de

Synthesis and characterization of palladium-cobalt alloy for new medical micro-devices

Science.gov (United States)

Kafrouni, Lina

According to Canadian Cancer Statistics, it is estimated that 196,900 Canadians will develop cancer and 78,000 will die of cancer in 2015. Given that tumor cells are more sensitive to a temperature increase than healthy ones, this property can be used in vivo to destroy the cancerous cells by elevation of body temperature, otherwise known as hyperthermia. Magnetic hyperthermia is a promising technique for cancer treatment because of ease in targeting the cancerous cells using magnetic nanoparticles (MNPs) and hence having fewer side effects than chemotherapy and radiotherapy. Despite the use of magnetic hyperthermia to treat cancer for thousands of years, the challenge of only heating malignant cells remains daunting. Thus, oncologists often use the heat treatment in combination with radiotherapy or chemotherapy or both. The combined approach results in eliminating many cancer cells in addition to making the resistant cancer cells more vulnerable to other treatments. To use stand-alone magnetic hyperthermia therapy, difficulties in surface modification of magnetic particles for selective uptake by cancerous cells and stability as well as magnetic properties for high heating capacity (> 1000 W/g) must be overcome. The ultimate objective of this thesis is to synthesize an excellent candidate for a powerful magnetic hyperthermia. Due to rapid advances in nanotechnology, a synthesis method of nanoparticles (NPs) with the ability to rigorously control the structure and morphology, such as size, shape and crystallinity, is needed. Electrodeposition is a versatile method for the synthesis of metal NPs directly and selectively onto conductive substrates, simply by regulating applied current or voltage. Furthermore, the particles size and the shape are easily controllable. Besides, studies have shown that the electrodeposition technique is of great utility in the fabrication of nanocrystalline palladium-cobalt (PdCo) alloys. The primary goal of this project is to synthesize

High throughput screening of Pd-alloys for H2 separation membranes studied by hydrogenography and CVM

Energy Technology Data Exchange (ETDEWEB)

Westerwaal, R.J.; Dam, B. [Delft University of Technology, Department of Chemical Engineering, Materials for Energy Conversion and Storage, Julianaweg 136, 2628 BL Delft (Netherlands); Den Besten, C.; Slaman, M. [Department of Physics and Astronomy, Vrije Universiteit Amsterdam, De Boelelaan 1081, 1081 HV Amsterdam (Netherlands); Nanuc, D.E.; Boettger, A.J. [Department of Materials Science and Engineering, Delft University of Technology, Mekelweg 2, 2628 CD Delft (Netherlands); Haije, W.G. [Energy research Centre of The Netherlands, Westerduinweg 3, 1755 LE Petten (Netherlands)

2011-01-15

The search for and development of stable Pd-based membranes for hydrogen separation applications with resistance to hydrogen embrittlement and cracking is a challenging and time-consuming task. Membrane failure is most often caused by the occurrence of the {alpha}-{beta} phase transition during hydrogen absorption and desorption by the Pd-alloy below the critical temperature. By finding a suitable alloy with a critical temperature below room temperature, the membrane lifetime can be extended tremendously. Here we present a combinatorial approach that enables the fast screening of phase transitions in multi-component Pd-alloys for hydrogen separation membranes by experiments and thermodynamic calculations. The method is applied to the well-documented Pd-Cu alloy compositions. Hydrogenography, a compositional gradient thin film technique, is used to experimentally investigate the alloy compositions. Using a new phenomenological method to determine the critical temperature from hydrogenography measurements, we show that the experimental results and the calculations, using the Cluster Variation Method (CVM), agree well with the phase boundaries and critical temperatures reported in literature. Our results show that the combined capabilities of hydrogenography and CVM enable an efficient screening of promising multi-component alloys for which thermodynamic data are scarce or absent.

Characterization of intracellular palladium nanoparticles synthesized by Desulfovibrio desulfuricans and Bacillus benzeovorans

Energy Technology Data Exchange (ETDEWEB)

Omajali, Jacob B., E-mail: JBO037@bham.ac.uk, E-mail: jbomajali@gmail.com; Mikheenko, Iryna P. [University of Birmingham, Unit of Functional Bionanomaterials, School of Biosciences, Institute of Microbiology and Infection (United Kingdom); Merroun, Mohamed L. [University of Granada, Department of Microbiology, Faculty of Sciences (Spain); Wood, Joseph [University of Birmingham, School of Chemical Engineering (United Kingdom); Macaskie, Lynne E. [University of Birmingham, Unit of Functional Bionanomaterials, School of Biosciences, Institute of Microbiology and Infection (United Kingdom)

2015-06-15

Early studies have focused on the synthesis of palladium nanoparticles within the periplasmic layer or on the outer membrane of Desulfovibrio desulfuricans and on the S-layer protein of Bacillus sphaericus. However, it has remained unclear whether the synthesis of palladium nanoparticles also takes place in the bacterial cell cytoplasm. This study reports the use of high-resolution scanning transmission electron microscopy with a high-angle annular dark field detector and energy dispersive X-ray spectrometry attachment to investigate the intracellular synthesis of palladium nanoparticles (Pd NPs). We show the intracellular synthesis of Pd NPs within cells of two anaerobic strains of D. desulfuricans and an aerobic strain of B. benzeovorans using hydrogen and formate as electron donors. The Pd nanoparticles were small and largely monodispersed, between 0.2 and 8 nm, occasionally from 9 to 12 nm with occasional larger nanoparticles. With D. desulfuricans NCIMB 8307 (but not D. desulfuricans NCIMB 8326) and with B. benzeovorans NCIMB 12555, the NPs were larger when made at the expense of formate, co-localizing with phosphate in the latter, and were crystalline, but were amorphous when made with H{sub 2,} with no phosphorus association. The intracellular Pd nanoparticles were mainly icosahedrons with surfaces comprising {111} facets and about 5 % distortion when compared with that of bulk palladium. The particles were more concentrated in the cell cytoplasm than the cell wall, outer membrane, or periplasm. We provide new evidence for synthesis of palladium nanoparticles within the cytoplasm of bacteria, which were confirmed to maintain cellular integrity during this synthesis.

Silver-palladium catalysts for the direct synthesis of hydrogen peroxide

Science.gov (United States)

Khan, Zainab; Dummer, Nicholas F.; Edwards, Jennifer K.

2017-11-01

A series of bimetallic silver-palladium catalysts supported on titania were prepared by wet impregnation and assessed for the direct synthesis of hydrogen peroxide, and its subsequent side reactions. The addition of silver to a palladium catalyst was found to significantly decrease hydrogen peroxide productivity and hydrogenation, but crucially increase the rate of decomposition. The decomposition product, which is predominantly hydroxyl radicals, can be used to decrease bacterial colonies. The interaction between silver and palladium was characterized using scanning electron microscopy, X-ray diffraction, X-ray photoelectron spectroscopy (XPS) and temperature programmed reduction (TPR). The results of the TPR and XPS indicated the formation of a silver-palladium alloy. The optimal 1% Ag-4% Pd/TiO2 bimetallic catalyst was able to produce approximately 200 ppm of H2O2 in 30 min. The findings demonstrate that AgPd/TiO2 catalysts are active for the synthesis of hydrogen peroxide and its subsequent decomposition to reactive oxygen species. The catalysts are promising for use in wastewater treatment as they combine the disinfectant properties of silver, hydrogen peroxide production and subsequent decomposition. This article is part of a discussion meeting issue 'Providing sustainable catalytic solutions for a rapidly changing world'.

Design study of fuel circulating system using Pd-alloy membrane isotope separation method

International Nuclear Information System (INIS)

Naito, T.; Yamada, T.; Yamanaka, T.; Aizawa, T.; Kasahara, T.; Nishikawa, M.; Asami, N.

1980-01-01

Design study on the fuel circulating system (FCS) for a tokamak experimental fusion reactor (JXFR) has been carried out to establish the system concept, to plan the development program, and to evaluate the feasibility of diffusion system. The FCS consists of main vacuum system, fuel gas refiners, isotope separators, fuel feeders, and auxiliary systems. In the system design, Pd-alloy membrane permeation method is adopted for fuel refining and isotope separating. All impurities are effectively removed and hydrogen isotopes are sufficiently separated by Pd-alloy membrane. The isotope separation system consists of 1st (47 separators) and 2nd (46 separators) cascades for removing protium and separating deuterium, respectively. In the FCS, while cryogenic distillation method appears to be practicable, Pd-alloy membrane diffusion method is attractive for isotope separation and refining of fuel gas. The choice will have to be based on reliability, economic, and safety analyses

Hydrogen solubility and permeability of Nb-W-Mo alloy membrane

International Nuclear Information System (INIS)

Awakura, Y.; Nambu, T.; Matsumoto, Y.; Yukawa, H.

2011-01-01

Research highlights: → The concept for alloy design of Nb-based hydrogen permeable membrane has been applied to Nb-W-Mo ternary alloy in order to improve further the resistance to hydrogen embrittlement and hydrogen permeability. → The alloying effects of Mo on the hydriding properties of Nb-W alloy have been elucidated. → The addition of Mo and/or W into niobium improves the resistance to hydrogen embrittlement by reducing the dissolved hydrogen concentration in the alloy. → Nb-W-Mo alloy possesses excellent hydrogen permeability together with strong resistance to hydrogen embrittlement. - Abstract: The alloying effects of molybdenum on the hydrogen solubility, the resistance to hydrogen embrittlement and the hydrogen permeability are investigated for Nb-W-Mo system. It is found that the hydrogen solubility decreases by the addition of molybdenum into Nb-W alloy. As a result, the resistance to hydrogen embrittlement improves by reducing the hydrogen concentration in the alloy. It is demonstrated that Nb-5 mol%W-5 mol%Mo alloy possesses excellent hydrogen permeability without showing any hydrogen embrittlement when used under appropriate hydrogen permeation conditions, i.e., temperature and hydrogen pressures.

Water Gas Shift Reaction with A Single Stage Low Temperature Membrane Reactor

Energy Technology Data Exchange (ETDEWEB)

Ciora, Richard J [Media and Process Technology Inc., Pittsburgh, PA (United States); Liu, Paul KT [Media and Process Technology Inc., Pittsburgh, PA (United States)

2013-12-31

Palladium membrane and Palladium membrane reactor were developed under this project for hydrogen separation and purification for fuel cell applications. A full-scale membrane reactor was designed, constructed and evaluated for the reformate produced from a commercial scale methanol reformer. In addition, the Pd membrane and module developed from this project was successfully evaluated in the field for hydrogen purification for commercial fuel cell applications.

External-beam PIXE spectrometry for the study of Punic jewellery (SW Spain): The geographical provenance of the palladium-bearing gold

International Nuclear Information System (INIS)

Ontalba Salamanca, M.A.; Gomez-Tubio, B.; Ortega-Feliu, I.; Respaldiza, M.A.; Luisa de la Bandera, M.; Ovejero Zappino, G.; Bouzas, A.; Gomez-Moron, A.

2006-01-01

This paper presents the study of a set of Punic gold items (400 B.C.), from the Museum of Cadiz (Spain). An external beam set-up has been employed for the absolutely non-destructive analysis of the objects. PIXE spectrometry has been performed in order to characterize the metallic alloys and the manufacturing techniques. Compositional differences have been found and soldering procedures have been identified. By comparison with the rings and other coetaneous jewellery, the presence of palladium in the bulk alloy of the earrings can be pointed out. The geographical provenance of the palladium-bearing gold is discussed based on geological and archaeological considerations

External-beam PIXE spectrometry for the study of Punic jewellery (SW Spain): The geographical provenance of the palladium-bearing gold

Energy Technology Data Exchange (ETDEWEB)

Ontalba Salamanca, M.A. [Departamento de Fisica, Escuela Politecnica, Universidad de Extremadura, Avda. de la Universidad s/n., 10071 Caceres (Spain)]. E-mail: ontalba@unex.es; Gomez-Tubio, B. [Centro Nacional de Aceleradores, Sevilla (Spain); Ortega-Feliu, I. [Centro Nacional de Aceleradores, Sevilla (Spain); Respaldiza, M.A. [Centro Nacional de Aceleradores, Sevilla (Spain); Luisa de la Bandera, M. [Departamento de Arqueologia, Universidad de Sevilla (Spain); Ovejero Zappino, G. [Cobre Las Cruces SA, Gerena, Sevilla (Spain); Bouzas, A. [Instituto Andaluz de Patrimonio Historico, Sevilla (Spain); Gomez-Moron, A. [Instituto Andaluz de Patrimonio Historico, Sevilla (Spain)

2006-08-15

This paper presents the study of a set of Punic gold items (400 B.C.), from the Museum of Cadiz (Spain). An external beam set-up has been employed for the absolutely non-destructive analysis of the objects. PIXE spectrometry has been performed in order to characterize the metallic alloys and the manufacturing techniques. Compositional differences have been found and soldering procedures have been identified. By comparison with the rings and other coetaneous jewellery, the presence of palladium in the bulk alloy of the earrings can be pointed out. The geographical provenance of the palladium-bearing gold is discussed based on geological and archaeological considerations.

A nanoflower shaped gold-palladium alloy on graphene oxide nanosheets with exceptional activity for electrochemical oxidation of ethanol

International Nuclear Information System (INIS)

Wang, Qiyu; Cui, Xiaoqiang; Zhang, Xiaoming; Liu, Chang; Xue, Tianyu; Wang, Haitao; Zheng, Weitao; Guan, Weiming

2014-01-01

We report on a new and facile method for the preparation of well-dispersed gold-palladium (AuPd) flower-shaped nanostructures on sheets of graphene oxide (GO). Transmission electron microscopy and high angle annular dark field STEM were used to characterize the morphology and composition of the new nanohybrids. The AuPd/GO composites display high electrocatalytic activity for the oxidation of ethanol in strongly alkaline medium as examined by cyclic voltammetry and chronoamperometry. Both the current density (13.16 mA · cm −2 at a working potential of −0.12 V) and the long-time stability are superior to a commercial Pd-on-carbon catalyst which is attributed to the cooperative action of the catalytic activities of Au and Pd, and the good dispersion of the alloy on the nanosheets. (author)

Development of composite metallic membranes for hydrogen purification

International Nuclear Information System (INIS)

Gaillard, F.

2003-12-01

Fuel cells are able to convert chemical energy into electric power. There are different types of cells; the best for automotive applications are Proton Exchange Membrane Fuel Cells. But, these systems need hydrogen of high purity. However, fuel reforming generates a mixture of gases, from which hydrogen has to be extracted before supplying the electrochemical cell. The best way for the purification of hydrogen is the membrane separation technology. Palladium is selectively permeable to hydrogen and this is the reason why this metal is largely used for the membrane development. This work deals with the development of hydrogen-selective membranes by deposition of a thin film of palladium onto a porous mechanical support. For this, we have used the electroless plating technique: a palladium salt and a reducing agent are mixed and the deposition takes place onto the catalytic surface of the substrate. After bibliographic investigations, experimental studies have been performed first with a dense metallic substrate in order to better understand the different parameters controlling the deposition. First of all, potentiometric measurements have been carried out to follow the electrochemical reactions in the bath. Then, kinetic measurements of the coating thickness have been recorded to understand the effect of the bath conditions on the yield and the adhesion of the film. Finally, the electroless plating method has been applied to deposit palladium membranes onto porous stainless steel substrates. After optimisation, the resulting membranes were tested for their hydrogen permeation properties. (author)

Development of Hydrogen Separation Module with Structured Catalyst for Use in Membrane Reformer

International Nuclear Information System (INIS)

Isamu Yasuda; Tatsuya Tsuneki; Yoshinori Shirasaki; Toru Shimamori; Hidekazu Shigaki; Hiroyuki Tanaka

2006-01-01

A new type of hydrogen separation module for use in a membrane reformer was proposed and developed. The new module, what we call MOC (Membrane On Catalyst), was designed to have a membrane of palladium-based alloy prepared on the surface of the tubular structured catalyst that has catalytic activity for steam reforming reaction, thermal expansion matching with the membrane material, proper porosity, mechanical strength and thermal conductivity. The best composition of the structured catalyst was identified in the composites of metallic Ni and YSZ (Yttria-Stabilized Zirconia). A hydrogen separation module was manufactured by electroless plating of Pd with thickness of 7 to 15 microns on the surface of porous sintered tube of Ni-YSZ with an approximate size of 9 mm in diameter and 100 mm in length. The hydrogen permeability measurements have shown hydrogen flux of 25 to 35 cc/min at 550 to 600 C, which is higher than the permeability of the conventional modules using rolled Pd film. (authors)

Modelling and sequential simulation of multi-tubular metallic membrane and techno-economics of a hydrogen production process employing thin-layer membrane reactor

KAUST Repository

Shafiee, Alireza

2016-09-24

A theoretical model for multi-tubular palladium-based membrane is proposed in this paper and validated against experimental data for two different sized membrane modules that operate at high temperatures. The model is used in a sequential simulation format to describe and analyse pure hydrogen and hydrogen binary mixture separations, and then extended to simulate an industrial scale membrane unit. This model is used as a sub-routine within an ASPEN Plus model to simulate a membrane reactor in a steam reforming hydrogen production plant. A techno-economic analysis is then conducted using the validated model for a plant producing 300 TPD of hydrogen. The plant utilises a thin (2.5 μm) defect-free and selective layer (Pd75Ag25 alloy) membrane reactor. The economic sensitivity analysis results show usefulness in finding the optimum operating condition that achieves minimum hydrogen production cost at break-even point. A hydrogen production cost of 1.98 $/kg is estimated while the cost of the thin-layer selective membrane is found to constitute 29% of total process capital cost. These results indicate the competiveness of this thin-layer membrane process against conventional methods of hydrogen production. © 2016 Hydrogen Energy Publications LLC

Determination of palladium content in palladium-alumina/palladium-silica/palladium-tin oxide catalyst for nuclear reactor applications

International Nuclear Information System (INIS)

Sharma, P.K.; Bassan, M.K.T.; Avhad, D.K.; Singhal, R.K.

2012-01-01

Alumina and silica act as support for finely divided palladium metal powder in synthesis of catalyst. These catalyst (Pd-Al 2 O 3 , Pd-SiO 2 and Pd-SnO 2 ) used in nuclear power reactor (moderator cover gas system) for the conversion of hydrogen. In Indian nuclear power programme these catalyst are regularly used in Kaiga 1 and 2 and Rajasthan atomic power plant 3 and 4. The performance of the catalyst, solely depends on the concentration of palladium, which is the active component in this catalyst composition. Therefore it is highly desirable to have rouged analytical methodology for the accurate estimation of palladium. Leaching of Pd from the bulk matrix is tedious due to the less reactive nature of Pd therefore complete solubilization of the matrix is carried out by fusion method

Reducing Stress-Corrosion Cracking in Bearing Alloys

Science.gov (United States)

Paton, N. E.; Dennies, D. P.; Lumsden, I., J.b.

1986-01-01

Resistance to stress-corrosion cracking in some stainless-steel alloys increased by addition of small amounts of noble metals. 0.75 to 1.00 percent by weight of palladium or platinum added to alloy melt sufficient to improve properties of certain stainless steels so they could be used in manufacture of high-speed bearings.

PALLADIUM-FACILITATED ELECTROLYTIC DECHLORINATION OF 2-CHLOROBIPHENYL USING A GRANULAR-GRAPHITE ELECTRODE.

Science.gov (United States)

Palladium-assisted electrocatalytic dechlorination of 2-chlorobiphenyl (2-Cl BP) in aqueous solutions was conducted in a membrane-separated electrochemical reactor with granular-graphite packed electrodes. The dechlorination took place at a granular-graphite cathode while Pd was ...

Palladium-based electrocatalysts for ethanol oxidation reaction in DEFC

International Nuclear Information System (INIS)

Moraes, L.P.R. de; Elsheikh, A.; Silva, E. L. da; Radtke, C.; Amico, S.C.; Malfatti, C.F.

2014-01-01

Direct ethanol fuel cells require the use of electrocatalysts to promote bond cleavage of the ethanol molecule in an efficient way. Currently, most electrocatalysts contain platinum, which enables improved catalytic activity and stability in acidic media. However platinum presents high cost and low availability. Based on that, novel catalysts have been developed, such as those based on palladium and its alloys, which have attained excellent results in the oxidation of ethanol in alkaline media. In this work, Pd, PdSn and PdNiSn catalysts supported on Vulcan XC72R carbon were synthesized via impregnation/reduction. The electrocatalysts were characterized by RBS, XRD and cyclic voltammetry. The X-ray diffraction results showed the formation of an alloy and not the deposition of isolated elements. The synthesized catalysts displayed good catalytic activity, as observed by cyclic voltammetry, being the best electrochemical performance achieved by the ternary alloy. (author)

Synthesis, characterization and optimization of platinum-alloy nanoparticle catalysts in proton exchange membrane fuel cells

Science.gov (United States)

Srivastava, Ratndeep

Renewable hydrogen-fuelled proton exchange membrane (PEMFC) fuel cells have consistently demonstrated great promise as a future source of energy due to their high conversion efficiency, lower temperature of operation and lack of greenhouse emissions. One of the major impediments in the commercialization of polymer electrolyte membrane fuel cells is the insufficient catalytic reactivity and higher cost of Pt electrocatalysts which are utilized for the electroreduction of oxygen from air. This dissertation focuses primarily on a family of Pt alloy fuel cell electrocatalysts referred to as de-alloyed core-shell electrocatalysts. These materials are bimetallic or multimetallic nanoparticles, mostly supported on conductive supports which were first described in a dissertation by Dr. S. Koh earlier in 2009.1 De-alloyed Pt nanoparticle electrocatalysts are formed from base metal rich binary Pt-M and ternary Pt-M1-M 2 (M, M1, M2 = Cu, Co, Ni, Fe and Cr) alloy nanoparticle precursors. The precursors are transformed and activated by electrochemical selective dissolution of the less noble metal component of the precursors (de-alloying). They have shown exceptional activity for oxygen reduction reaction (ORR) in idealized electrochemical half cell measurements, in particular rotating disk electrode experiments. However, these materials were never tested or implemented in realistic Membrane Electrode Assemblies (MEA) and single PEM fuel cells. The objective of this work was to implement de-alloyed Pt particle catalysts in realistic fuel cell electrode layers as well as a detailed characterization of their behavior and stability. The major challenges of MEA implementation consists of the behavior of the new nanostructured electrocatalysts inside the complex three-phase interface of polymer membrane ionomer, liquid water, metal catalyst, support, and reactant gas. Activity measurements were followed by medium and long-term durability analysis by potential cycling of the membrane

Crystal size effect on the electrochemical oxidation of formate on carbon-supported palladium nanoparticles

International Nuclear Information System (INIS)

Santos, Rayana Marcela Izidoro da Silva; Nakazato, Roberto Zenhei; Ciapina, Eduardo Goncalves

2016-01-01

Full text: The electrochemical oxidation of formate in alkaline electrolytes has emerged an a promising anodic reaction in the Direct Formate Fuel Cells[1]. Although palladium is considered to be one of the best electro catalyst for the oxidation of formate, important structure-activity relationships are still not understood. In the present work, we investigated the effect of the size of the palladium crystals in the electrochemical oxidation of formate in 0.1 mol L -1 KOH. Carbon-supported palladium nanoparticles (Pd/C) were prepared by chemical reduction of palladium (II) chloride in aqueous media by sodium borohydride in the presence of varying quantities of sodium citrate in the reaction media to obtain metallic crystals with distinct sizes. Analysis of the X-ray diffraction profile revealed the presence of palladium crystals in the range of 6 to 19 nm. Potentiostatic oxidation of formate on the distinct Pd/C samples revealed a volcano-like dependence of the specific activity with the size of the palladium crystals, presenting the highest activity for crystals around 7.5 nm. Reference: [1] A.M. Bartrom, J.L. Haan, The direct formate fuel cell with an alkaline anion exchange membrane, J. Power Sources. 214 (2012) 68-74. (author)

Migration behavior of palladium in UO2, (3)

International Nuclear Information System (INIS)

Yoneyama, Mitsuru; Sato, Seichi; Ohashi, Hiroshi; Ogawa, Toru; Ito, Akinori; Fukuda, Kousaku.

1992-08-01

Palladium (Pd) is easily released from UO 2 kernels in HTGR coated fuel particles, and reacts with SiC coating layer. In addition, Pd is one of metallic fission products in irradiation UO 2 , which constitutes in dissoluble residue in reprocessing of LWR fuels. In the present investigation, the migration of palladium in UO 2 was examined by heating diffusion pairs sandwiched Pd foil between UO 2 wafers at 1300 ∼ 1800degC. Experiments were also carried out on affinity of Pd to UP 2 and a formation of U-Pd alloy. Pd was found mainly in the pores of UO 2 . The maximum depth intruded by Pd in fairly large amount was more than 100 μm for UO 2 with 90%TD and 50μm for UO 2 with 95%TD, while the maximum length of open pores was 330 μm for UO 2 with 90%TD, and 50 m for that with 95%TD. Fused Pd wetted UO 2 very much. Pd intruded deeply into UO 2 , especially in the edge of Pd droplet. Furthermore, U was detected either in precipitates or the Pd source with α-Pd phase of U-Pd alloy containing Pd at about 10at%. This fact indicates that Pd highly reacts with UO 2 . From the above results, the transport of Pd in UO 2 was explained by the model of gaseous diffusion through pores in UO 2 , which is retarded by formation of U-Pd alloy. It is also indicated that UPd 3 forms even at the oxygen potential condition of O/U ratio, which is a little higher than 2.00 on the basis of thermodynamic calculation. (author)

Laccases as palladium oxidases.

Science.gov (United States)

Mekmouche, Yasmina; Schneider, Ludovic; Rousselot-Pailley, Pierre; Faure, Bruno; Simaan, A Jalila; Bochot, Constance; Réglier, Marius; Tron, Thierry

2015-02-01

The first example of a coupled catalytic system involving an enzyme and a palladium(ii) catalyst competent for the aerobic oxidation of alcohol in mild conditions is described. In the absence of dioxygen, the fungal laccase LAC3 is reduced by a palladium(0) species as evidenced by the UV/VIS and ESR spectra of the enzyme. During the oxidation of veratryl alcohol performed in water, at room temperature and atmospheric pressure, LAC3 regenerates the palladium catalyst, is reduced and catalyzes the four-electron reduction of dioxygen into water with no loss of enzyme activity. The association of a laccase with a water-soluble palladium complex results in a 7-fold increase in the catalytic efficiency of the complex. This is the first step in the design of a family of renewable palladium catalysts for aerobic oxidation.

Tritium recovery from tritiated water with a two-stage palladium membrane reactor

International Nuclear Information System (INIS)

Birdsell, S.A.; Willms, R.S.

1997-01-01

A process to recover tritium from tritiated water has been successfully demonstrated at TSTA. The 2-stage palladium membrane reactor (PMR) is capable of recovering tritium from water without generating additional waste. This device can be used to recover tritium from the substantial amount of tritiated water that is expected to be generated in the International Thermonuclear Experimental Reactor both from torus exhaust and auxiliary operations. A large quantity of tritiated waste water exists world wide because the predominant method of cleaning up tritiated streams is to oxidize tritium to tritiated water. The latter can be collected with high efficiency for subsequent disposal. The PMR is a combined catalytic reactor/permeator. Cold (non-tritium) water processing experiments were run in preparation for the tritiated water processing tests. Tritium was recovered from a container of molecular sieve loaded with 2,050 g (2,550 std. L) of water and 4.5 g of tritium. During this experiment, 27% (694 std. L) of the water was processed resulting in recovery of 1.2 g of tritium. The maximum water processing rate for the PMR system used was determined to be 0.5 slpm. This correlates well with the maximum processing rate determined from the smaller PMR system on the cold test bench and has resulted in valuable scale-up and design information

Tritium recovery from tritiated water with a two-stage palladium membrane reactor

Energy Technology Data Exchange (ETDEWEB)

Birdsell, S.A.; Willms, R.S.

1997-04-01

A process to recover tritium from tritiated water has been successfully demonstrated at TSTA. The 2-stage palladium membrane reactor (PMR) is capable of recovering tritium from water without generating additional waste. This device can be used to recover tritium from the substantial amount of tritiated water that is expected to be generated in the International Thermonuclear Experimental Reactor both from torus exhaust and auxiliary operations. A large quantity of tritiated waste water exists world wide because the predominant method of cleaning up tritiated streams is to oxidize tritium to tritiated water. The latter can be collected with high efficiency for subsequent disposal. The PMR is a combined catalytic reactor/permeator. Cold (non-tritium) water processing experiments were run in preparation for the tritiated water processing tests. Tritium was recovered from a container of molecular sieve loaded with 2,050 g (2,550 std. L) of water and 4.5 g of tritium. During this experiment, 27% (694 std. L) of the water was processed resulting in recovery of 1.2 g of tritium. The maximum water processing rate for the PMR system used was determined to be 0.5 slpm. This correlates well with the maximum processing rate determined from the smaller PMR system on the cold test bench and has resulted in valuable scale-up and design information.

The generalized lewis acid-base titration of palladium and niobium

Science.gov (United States)

Cima, M.; Brewer, L.

1988-12-01

The high thermodynamic stability of alloys composed of platinum group metals and group IVB and VB metals has been explained by an electronic interaction analogous to the Lewis acid-base concept for nontransition elements. The analogy is further demonstrated by the titration of palladium by addition of niobium. The activity of niobium in solid palladium was measured as a function of concentration by solid-state galvanic cells and study of the ternary oxide phase diagram. The galvanic cells were of the type Pt/NbO2,Nb2O4.8/YDTJNbOy,Nbpd/Pt where the solid electrolyte is yttria-doped thoria (YDT). Ternary phase diagrams for the Pd-Nb-0 and Rh-Nb-0 systems were obtained by characterizing samples equilibrated at 1000 °C. The phase relationships found in the ternary diagrams were also used to derive thermochemical data for the alloys. Thermochemical quantities for other acid-base stabilized alloys such as Nb-Rh, Ti-Pd, and Ti-Rh were also measured. The excess partial molar ΔGxs/R of niobium at infinite dilution was determined to be -31 kilo-Kelvin at 1000 °C, and the AG°JR of formation of a mole of NbPd3.55 is —21 kilo-Kelvin. These results and those for the other systems are used to assess the importance of valence electron configuration, nuclear charge, and crystal field effects in the context of generalized Lewis acid-base theory. It is concluded that both the nuclear charge of the atom and crystal field splitting of the valence orbitals significantly affect the basicity of the platinum group metals.

Polymer-immobilized liquid membrane transport of palladium (II) from nitric acid media using some thia extractants as novel receptors

International Nuclear Information System (INIS)

Shukla, J.P.

1996-01-01

Carrier-facilitated co-transport of Pd (II) from dilute acidic nitrate solutions was examined across a polymer-immobilized liquid membrane (PILM) deploying S 6 -pentano-36 (S 6 -P-36), bis-(2-ethylhexyl) sulfoxide (BESO) and bis (2, 4, 4 trimethyl pentyl) monothio phosphinic acid (Cyanex 302) as the novel receptors. The study carried out to distinguish the driving force between H + and NO 3 - ion for the cation transport across PILM, indicated that NO 3 - ion not the H + ion seems to be the driving force for Pd (II) transport under the present conditions for both BESO-PILM and S 6 -P-36-PILM systems. Recovery of palladium from acidic process effluents generated in Purex reprocessing of spent fuels was successfully achieved. 39 refs., 8 figs., 7 tabs

Determination of the Debye-Waller Factor of hydrogen in Palladium and Palladium Silver alloy

International Nuclear Information System (INIS)

Khodabakhsh, R.

1986-01-01

The mean square amplitude of the vibrating hydrogen in metals can be determined by using coherent elastic neutron scattering experiments, inelastic one-phonon scattering measurements. To determine the D.W.F. Debye-Waller Factor from the coherent elastic scattering measurements, information about the positions of atoms within the unit is required, and vice versa. The main difficulty concerning the determination of the D.W.F. from the inelastic experiment is in elimination of multi-phonon contribution from the measured spectrum. However, the D.W.F. of hydrogen in palladium has been usually determined by the intensity of the quasi-elastic line. An integration of the measured scattering law S(Q,W) at constant Q, over a certain energy window ΔE, results in the quasi-elastic intensity. To obtain an accurate result, this window has to be chosen large enough to comprise most of the quasi-elastic line, but sufficiently small so that the phonon contributions are small. The MARX spectrometer is ideally constructed for this type of measurement where the window is about +-1 Mev for incident neutron wavelength, =4.115 A. Thus, the quasi-elastic scattering method was considered the best method of determining the D.W.F. of hydrogen in palladium using the MARX spectrometer. However, if the acoustic part overlaps with the quasi-elastic part, one has to obtain the D.W.F. by fitting the data to a quasi-elastic model. The work to be reported here is the investigation of variations of the D.W.F. of hydrogen in Pd and PdAgsub(0.085) with temperature and extension of the available data to as high a temperature as possible. Therefore the integrated intensity of incoherent quasi-elastic neutron scattering by proton in polycrystallin Pd/H and PdAgsub(0.085)/H was investigated as a function of the scattering vector Q. A quasi-harmonic D.W.F. behaviour was observed at elevated temperatures. The observed Debye-Waller Factor depends strongly on the form of the amplitude weighted frequency

Membrane reforming in converting natural gas to hydrogen (part one)

Energy Technology Data Exchange (ETDEWEB)

Barba, D; Giacobbe, F; De Cesaris, A [Faculty of Chemical Engineering and Materials, University of L' Aquila (Italy); Farace, A; Iaquaniello, G; Pipino, A [TECHNIP-KTI S.p.a., Rome (Italy)

2008-07-15

Membrane reforming reactors (MRR) could play a key role in converting natural gas into hydrogen. The major advantage of MRR architecture is the possibility to shift the chemical equilibrium toward the right-hand side of the reaction, improving hydrogen production and allowing, the same time high methane conversion at relatively low temperatures such as 650 C. Such a low operating temperature makes it possible to locate the MRR downstream of a gas turbine, achieving an efficient hybrid system (power+hydrogen) with a significant reduction in energy consumption (around 10%). This paper discusses the whole innovative architecture where conventional tubular reforming is integrated with hydrogen permeable palladium membrane separators. The fundamental concepts are analyzed and integrated into a process scheme; the structural effects of variables design such as reactor temperature outlet, S/C ratio and recycle ratio throughout pinch and sensitivity analysis are described, and a comparison of the process economics with conventional hydrogen technology is presented at the end of the second part of this paper. The production of highly reliable, defect-free and reproducible, Pd-alloy membranes for selective hydrogen separation is a key issue in the proposed hybrid architecture. (author)

Superparamagnetic bimetallic iron-palladium nanoalloy: synthesis and characterization

Energy Technology Data Exchange (ETDEWEB)

Nazir, Rabia; Mazhar, Muhammad [Department of Chemistry, Quaid-i-Azam University, Islamabad 45320 (Pakistan); Akhtar, M Javed; Nadeem, M; Siddique, Muhammad [Physics Division, PINSTECH, PO Nilore, Islamabad 44000 (Pakistan); Shah, M Raza [HEJ Research Institute of Chemistry, University of Karachi, Karachi 75270 (Pakistan); Khan, Nawazish A [Material Science Laboratory, Department of Physics, Quaid-i-Azam University, Islamabad 45320 (Pakistan); Mehmood, Mazhar [National Centre for Nanotechnology, PIEAS, Islamabad 45650 (Pakistan); Butt, N M [Pakistan Science Foundation, Islamabad 44000 (Pakistan)], E-mail: mazhar42pk@yahoo.com

2008-05-07

Iron-palladium nanoalloy in the particle size range of 15-30 nm is synthesized by the relatively low temperature thermal decomposition of coprecipitated [Fe(Bipy){sub 3}]Cl{sub 2} and [Pd(Bipy){sub 3}]Cl{sub 2} in an inert ambient of dry argon gas. The silvery black Fe-Pd alloy nanoparticles are air-stable and have been characterized by EDX-RF, XRD, AFM, TEM, magnetometry, {sup 57}Fe Moessbauer and impedance spectroscopy. This Fe-Pd nanoalloy is in single phase and contains iron sites having up to 11 nearest-neighboring atoms. It is superparamagnetic in nature with high magnetic susceptibility, low coercivity and hyperfine field.

Methane-steam reforming by molten salt - membrane reactor using concentrated solar thermal energy

International Nuclear Information System (INIS)

Watanuki, K.; Nakajima, H.; Hasegawa, N.; Kaneko, H.; Tamaura, Y.

2006-01-01

By utilization of concentrated solar thermal energy for steam reforming of natural gas, which is an endothermic reaction, the chemical energy of natural gas can be up-graded. The chemical system for steam reforming of natural gas with concentrated solar thermal energy was studied to produce hydrogen by using the thermal storage with molten salt and the membrane reactor. The original steam reforming module with hydrogen permeable palladium membrane was developed and fabricated. Steam reforming of methane proceeded with the original module with palladium membrane below the decomposition temperature of molten salt (around 870 K). (authors)

Electrochemical catalytic activities of nanoporous palladium rods for methanol electro-oxidation

Energy Technology Data Exchange (ETDEWEB)

Wang, Xiaoguang; Wang, Weimin; Qi, Zhen; Zhao, Changchun; Ji, Hong; Zhang, Zhonghua [Key Laboratory for Liquid-Solid Structural Evolution and Processing of Materials (MOE), School of Materials Science and Engineering, Shandong University, Jingshi Road 73, Jinan 250061 (China)

2010-10-01

A novel electrocatalyst, nanoporous palladium (npPd) rods can be facilely fabricated by dealloying a binary Al{sub 80}Pd{sub 20} alloy in a 5 wt.% HCl aqueous solution under free corrosion conditions. The microstructure of these nanoporous palladium rods has been characterized using scanning electron microscopy and transmission electron microscopy. The results show that each Pd rod is several microns in length and several hundred nanometers in diameter. Moreover, all the rods exhibit a typical three-dimensional bicontinuous interpenetrating ligament-channel structure with length scale of 15-20 nm. The electrochemical experiments demonstrate that these peculiar nanoporous palladium rods (mixed with Vulcan XC-72 carbon powders to form a npPd/C catalyst) reveal a superior electrocatalytic performance toward methanol oxidation in the alkaline media. In addition, the electrocatalytic activity obviously depends on the metal loading on the electrode and will reach to the highest level (223.52 mA mg{sup -1}) when applying 0.4 mg cm{sup -2} metal loading on the electrode. Moreover, a competing adsorption mechanism should exist when performing methanol oxidation on the surface of npPd rods, and the electro-oxidation reaction is a diffusion-controlled electrochemical process. Due to the advantages of simplicity and high efficiency in the mass production, the npPd rods can act as a promising candidate for the anode catalyst for direct methanol fuel cells (DMFCs). (author)

Experiments on a ceramic electrolysis cell and a palladium diffuser at the tritium systems test assembly

International Nuclear Information System (INIS)

Konishi, Satoshi; Yoshida, Hiroshi; Ohno, Hideo; Naruse, Yuji; Coffin, D.O.; Walthers, C.R.; Binning, K.E.

1985-01-01

A ceramic electrolysis cell and a palladium diffuser are developed in Japan and is tested with tritium in Tritium Systems Test Assembly (TSTA) of the Los Alamos National Laboratory, in order to confirm the feasibility as possible upgrades for the fuel cleanup system (PCU). The ceramic electrolysis cell made of stabilized zirconia was operated at 630 0 C for an extended period with a mixture of 3% T 2 O in He carrier gas in the circulation system with oxidizing catalyst bed. The palladium diffuser was tested with circulated pure tritium gas at 280 0 C to verify the compatibility of the alloy with tritium, since the 3 He produced in the metal could cause a degradation. The isotopic effects were also measured for both devices

Sensitization to palladium in Europe

DEFF Research Database (Denmark)

Muris, Joris; Goossens, An; Gonçalo, Margarida

2015-01-01

BACKGROUND: Recently, sodium tetrachloropalladate (Na2 PdCl4 ) was found to be a more sensitive palladium patch test allergen than palladium dichloride (PdCl2 ). OBJECTIVES: To determine the optimal test concentration of Na2 PdCl4 , to evaluate the prevalence of palladium sensitization with Na2 P...... patch test concentration. Sensitization to palladium is almost as prevalent as sensitization to nickel. The sex distribution is different between nickel-sensitized and palladium-sensitized patients, suggesting different sources of exposure.......Cl4 and PdCl2 , and to compare the results with nickel sensitization in a European multicentre study. MATERIALS AND METHODS: In addition to the European or national baseline series including NiSO4 ·6H2 0 5% pet., consecutive patients were tested with PdCl2 and Na2 PdCl4 2%, 3% and 4% pet. in eight...... European dermatology clinics. The age and sex distributions were also evaluated in patients sensitized to nickel and palladium. RESULTS: In total, 1651 patients were tested. Relative to 3% Na2 PdCl4 , 4% Na2 PdCl4 did not add any information. Two per cent Na2 PdCl4 resulted in more doubtful reactions...

Oxygen kinetics and mechanism at electrocatalysts on the base of palladium-iron system

International Nuclear Information System (INIS)

Tarasevich, M.R.; Zhutaeva, G.V.; Bogdanovskaya, V.A.; Radina, M.V.; Ehrenburg, M.R.; Chalykh, A.E.

2007-01-01

Binary nanodispersed carbon XC72 supported PdFe catalysts with different atomic palladium-to-iron ratios are synthesized and studied in oxygen reduction reaction in acid solution at 60 o C. The Pd:Fe ratio was well controlled by the initial concentrations of Pd and Fe in the precursor solutions. The nanoparticles were characterized by transmission electron microscopy, X-ray diffractometry and X-ray photoelectron spectroscopy. The optimum Pd:Fe ratio for this reaction was determined to be 3:1. The comparison of activities of the catalysts with component ratios equaled 3:1 and 10:1 is shown that the activities are differed from each other by 10-15 times in advantage of catalyst with lesser content of palladium. This phenomenon can be related to the different particle size of both catalysts and different distribution of particles by size discovered by TEM method. The achievement of maximum activity near the ratio of Pd:Fe = 3:1 is due to as effect of alloy-forming and the influence of binary system component ratio and synthesis conditions on dispersity degree of metallic phase nanoparticles. Under optimal conditions of precursor mixture high-temperature pyrolysis, iron produces the stabilizing effect palladium. It gives rise to obtaining the uniform and finely divided (7-8 nm) metallic particles

Cu assisted synthesis of self-supported PdCu alloy nanowires with enhanced performances toward ethylene glycol electrooxidation

Science.gov (United States)

Yan, Bo; Xu, Hui; Zhang, Ke; Li, Shujin; Wang, Jin; Shi, Yuting; Du, Yukou

2018-03-01

Self-supported PdCu alloy nanowires fabricated by a facile one-pot method have been reported, which copper assists in the morphological transformation from graininess to nanowires. The copper incorporated with palladium to form alloy structures cannot only cut down the usage of noble metal but also enhance their catalytic performances. The catalysts with self-supported structure and proper ratio of palladium to copper show great activity and long-term stability for the electrooxidation of ethylene glycol in alkaline solution. Especially for Pd43Cu57, its mass activity reaches to 5570.83 mA mg-1, which is 3.12 times as high as commercial Pd/C. This study highlights an accessible strategy to prepare self-supported PdCu alloy nanowires and their potential applications in renewable energy fields.

l-Glutamic acid assisted eco-friendly one-pot synthesis of sheet-assembled platinum-palladium alloy networks for methanol oxidation and oxygen reduction reactions.

Science.gov (United States)

Shi, Ya-Cheng; Mei, Li-Ping; Wang, Ai-Jun; Yuan, Tao; Chen, Sai-Sai; Feng, Jiu-Ju

2017-10-15

In this work, bimetallic platinum-palladium sheet-assembled alloy networks (PtPd SAANs) were facilely synthesized by an eco-friendly one-pot aqueous approach under the guidance of l-glutamic acid at room temperature, without any additive, seed, toxic or organic solvent involved. l-Glutamic acid was served as the green shape-director and weak-stabilizing agent. A series of characterization techniques were employed to examine the morphology, structure and formation mechanism of the product. The architectures exhibited improved electrocatalytic activity and durable ability toward methanol oxidation reaction (MOR) and oxygen reduction reaction (ORR) in contrast with commercial Pt black and Pd black catalysts. This is ascribed to the unique structures of the obtained PtPd SAANs and the synergistic effects of the bimetals. These results demonstrate the potential application of the prepared catalyst in fuel cells. Copyright © 2017 Elsevier Inc. All rights reserved.

Synthesis of vanadium-doped palladium nanoparticles for hydrogen storage materials

Science.gov (United States)

Yamamoto, Yuki; Miyachi, Mariko; Yamanoi, Yoshinori; Minoda, Ai; Maekawa, Shunsuke; Oshima, Shinji; Kobori, Yoshihiro; Nishihara, Hiroshi

2011-12-01

Palladium-vanadium (Pd/V) alloy nanoparticles stabilized with n-pentyl isocyanide were prepared as new hydrogen storage materials by a facile polyol-based synthetic route with tetraethylene glycol and NaOH at 250 °C. The size distribution of the nanoparticles thus obtained featured two peaks at 4.0 ± 1.1 and 1.4 ± 0.3 nm in diameter, which were the mixture of Pd/V alloy and Pd nanoparticles. The ratio between the number of Pd/V and that of Pd nanoparticles was 51:49, and the Pd:V ratio of the overall product was 9:1 in wt%, indicating that the 4.0 nm Pd/V nanoparticles were composed of 81% Pd and 19% V. The inclusion of vanadium caused the increase in the d-spacing and thus expansion of lattice constant. A rapid increase in hydrogen content at low H2 pressures was observed for the Pd/V nanoparticles, and a 0.47 wt% H2 adsorption capacity was achieved under a H2 pressure of 10 MPa at 303 K. Hydrogen storage performances of Pd/V alloy nanoparticles was superior compared with Pd nanoparticles.

High temperature soldering of the VT14 titanium alloy

International Nuclear Information System (INIS)

Besednyj, V.A.

1978-01-01

Two methods of brazing the VT14 alloys have been investigated, as well as the effect of annealing and heating during brazing and on mechanical properties of this alloy. Contact reaction brazing using a palladium layer has been shown to be applicable for simple-shape products, while capillary brazing using Cu-Ti, Ni-Ti and Fe-Ti brazing alloy systems, for complex-shape products. Brazed joints strength is similar to the strength of the VT14 alloy. Heating during brazing (960 deg - 1160 deg C) and the following annealing (900 deg C) have but a slight effect on the properties of the base metal, reducing strength by 2-5% and increasing ductility by 10-20%

Palladium-cobalt particles as oxygen-reduction electrocatalysts

Science.gov (United States)

Adzic, Radoslav [East Setauket, NY; Huang, Tao [Manorville, NY

2009-12-15

The present invention relates to palladium-cobalt particles useful as oxygen-reducing electrocatalysts. The invention also relates to oxygen-reducing cathodes and fuel cells containing these palladium-cobalt particles. The invention additionally relates to methods for the production of electrical energy by using the palladium-cobalt particles of the invention.

Hydrogen permeation properties of Pd-coated V89.8Cr 10Y0.2 alloy membrane using WGS reaction gases

KAUST Repository

Jeon, Sungil

2013-05-01

The influence of co-existing gases on the hydrogen permeation was studied through a Pd-coated V89.8Cr10Y0.2 alloy membrane. Preliminary hydrogen permeation experiments have been confirmed that hydrogen flux was 6.26 ml/min/cm2 for a Pd-coated V 89.8Cr10Y0.2 alloy membrane (thick: 0.5 mm) using pure hydrogen as feed gas. Also, the hydrogen permeation flux decreased with decrease of hydrogen partial pressure at constant pressure when H 2/CO2 and H2/CO2/H2S mixture applied as feed gas respectively and permeation fluxes were satisfied with Sievert\\'s law in different feed conditions. It was found from XRD and SEM results after permeation test that the Pd-coated V89.8Cr 10Y0.2 alloy membrane had good stability and durability for various mixture feeding conditions. Copyright © 2013, Hydrogen Energy Publications, LLC. Published by Elsevier Ltd. All rights reserved.

Hydrogen permeation properties of Pd-coated V89.8Cr 10Y0.2 alloy membrane using WGS reaction gases

KAUST Repository

Jeon, Sungil; Park, Junghoon

2013-01-01

The influence of co-existing gases on the hydrogen permeation was studied through a Pd-coated V89.8Cr10Y0.2 alloy membrane. Preliminary hydrogen permeation experiments have been confirmed that hydrogen flux was 6.26 ml/min/cm2 for a Pd-coated V 89.8Cr10Y0.2 alloy membrane (thick: 0.5 mm) using pure hydrogen as feed gas. Also, the hydrogen permeation flux decreased with decrease of hydrogen partial pressure at constant pressure when H 2/CO2 and H2/CO2/H2S mixture applied as feed gas respectively and permeation fluxes were satisfied with Sievert's law in different feed conditions. It was found from XRD and SEM results after permeation test that the Pd-coated V89.8Cr 10Y0.2 alloy membrane had good stability and durability for various mixture feeding conditions. Copyright © 2013, Hydrogen Energy Publications, LLC. Published by Elsevier Ltd. All rights reserved.

Reductive dechlorination of 3,3',4,4'-tetrachlorobiphenyl (PCB77) using palladium or palladium/iron nanoparticles and assessment of the reduction in toxic potency in vascular endothelial cells

International Nuclear Information System (INIS)

Venkatachalam, Karthik; Arzuaga, Xabier; Chopra, Nitin; Gavalas, Vasilis G.; Xu, Jian; Bhattacharyya, Dibakar; Hennig, Bernhard; Bachas, Leonidas G.

2008-01-01

Palladium-based nanoparticles immobilized in polymeric matrices were applied to the reductive dechlorination of 3,3',4,4'-tetrachlorobiphenyl (PCB77) at room temperature. Two different dechlorination platforms were evaluated using (1) Pd nanoparticles within conductive polypyrrole films; or (2) immobilized Fe/Pd nanoparticles within polyvinylidene fluoride microfiltration membranes. For the first approach, the polypyrrole film was electrochemically formed in the presence of perchlorate ions that were incorporated into the film to counter-balance the positive charges of the polypyrrole chain. The film was then incubated in a solution containing tetrachloropalladate ions, which were exchanged with the perchlorate ions within the film. During this exchange, reduction of tetrachloropalladate by polypyrrole occurred, which led to the formation of palladium nanoparticles within the film. For the second approach, the membrane-supported Fe/Pd nanoparticles were prepared in three steps: polymerization of acrylic acid in polyvinylidene fluoride microfiltration membrane pores was followed by ion exchange of Fe 2+ , and then chemical reduction of the ferrous ions bound to the carboxylate groups. The membrane-supported iron nanoparticles were then soaked in a solution of tetrachloropalladate resulting in the deposition of Pd on the Fe surface. The nanoparticles prepared by both approaches were employed in the dechlorination of PCB77. The presence of hydrogen was required when the monometallic Pd nanoparticles were employed. The results indicate the removal of chlorine atoms from PCB77, which led to the formation of lower chlorinated intermediates and ultimately biphenyl. Toxicity associated with vascular dysfunction by PCB77 and biphenyl was compared using cultured endothelial cells. The data strongly suggest that the dechlorination system used in this study markedly reduced the proinflammatory activity of PCB77, a persistent organic pollutant

Palladium transport in SiC

International Nuclear Information System (INIS)

Olivier, E.J.; Neethling, J.H.

2012-01-01

Highlights: ► We investigate the reaction of Pd with SiC at typical HTGR operating temperatures. ► The high temperature mobility of palladium silicides within polycrystalline SiC was studied. ► Corrosion of SiC by Pd was seen in all cases. ► The preferential corrosion and penetration of Pd along grain boundaries in SiC was found. ► The penetration and transport of palladium silicides in SiC along grain boundaries was found. - Abstract: This paper reports on a transmission electron microscopy (TEM) and scanning electron microscopy (SEM) study of Pd corroded SiC. The reaction of Pd with different types of SiC at typical HTGR operating temperatures was examined. In addition the high temperature mobility of palladium silicides within polycrystalline SiC was investigated. The results indicated corrosion of the SiC by Pd in all cases studied. The corrosion leads to the formation of palladium silicides within the SiC, with the predominant phase found being Pd 2 Si. Evidence for the preferential corrosion and penetration of Pd along grain boundaries in polycrystalline SiC was found. The penetration and transport, without significant corrosion, of palladium silicides into polycrystalline SiC along grain boundaries was also observed. Implications of the findings with reference to the use of Tri Isotropic particles in HTGRs will be discussed.

Growth and sedimentation of fine particles produced in aqueous solutions of palladium sulfate and palladium sulfate-silver sulfate induced by gamma-ray irradiation

International Nuclear Information System (INIS)

Hatada, Motoyoshi; Jonah, C.D.

1994-10-01

It is known that palladium and palladium-silver fine particles were formed from deaerated aqueous solutions of palladium sulfate and palladium sulfate-silver sulfate induced by gamma-ray irradiation. Changes in particle size and with amount of particles in the solution with time during and after irradiation were studied using dynamic light scattering technique and UV spectrophotometer. The particles formed from palladium sulfate solution are found to be water-filled bulky particles of diameter of 200 nm, which grow by mutual coagulation even after irradiation was terminated. Average density depends on concentration of palladium ion in the solution and dose, and the lowest density was about 2 g/cm 3 for particles of 200 nm obtained from 0.06 mM solution by 2.4 kGy irradiation. The average density of the particles obtained from palladium sulfate-silver sulfate solutions was smaller than those obtained for the corresponding palladium sulfate solutions. Supersonic agitation destroyed coagulated precipitates to form fine particles, but did not form clusters of a few atoms. (author)

CoPd x oxygen reduction electrocatalysts for polymer electrolyte membrane and direct methanol fuel cells

International Nuclear Information System (INIS)

Mustain, William E.; Kepler, Keith; Prakash, Jai

2007-01-01

The electrochemical activity of carbon-supported cobalt-palladium alloy electrocatalysts of various compositions have been investigated for the oxygen reduction reaction in a 5 cm 2 single cell polymer electrolyte membrane fuel cell. The polarization experiments have been conducted at various temperatures between 30 and 60 deg. C and the reduction performance compared with data from a commercial Pt catalyst under identical conditions. Investigation of the catalytic activity of the CoPd x PEMFC system with varying composition reveals that a nominal cobalt-palladium atomic ratio of 1:3, CoPd 3 , exhibits the best performance of all studied catalysts, exhibiting a catalytic activity comparable to the commercial Pt catalyst. The ORR on CoPd 3 has a low activation energy, 52 kJ/mol, and a Tafel slope of approximately 60 mV/decade, indicating that the rate-determining step is a chemical step following the first electron transfer step and may involve the breaking of the oxygen bond. The CoPd 3 catalyst also exhibits excellent chemical stability, with the open circuit cell voltage decreasing by only 3% and the observed current decreasing by only 10% at 0.8 V over 25 h. The CoPd 3 catalyst also exhibits superior tolerance to methanol crossover poisoning than Pt

Study and development of membrane electrode assemblies for Proton Exchange Membrane Fuel Cell (PEMFC) with palladium based catalysts

International Nuclear Information System (INIS)

Bonifacio, Rafael Nogueira

2013-01-01

PEMFC systems are capable of generating electricity with high efficiency and low or no emissions, but durability and cost issues prevent its large commercialization. In this work MEA with palladium based catalysts were developed, Pd/C, Pt/C and alloys PdPt/C catalysts with different ratios between metals and carbon were synthesized and characterized. A study of the ratio between catalyst and Nafion Ionomer for formation of high performance triple-phase reaction was carried out, a mathematical model to implement this adjustment to catalysts with different relations between metal and support taking into account the volumetric aspects of the catalyst layer was developed and then a study of the catalyst layer thickness was performed. X-ray diffraction, Transmission and Scanning Electron Microscopy, X-ray Energy Dispersive, Gas Pycnometry, Mercury Intrusion Porosimetry, Gas adsorption according to the BET and BJH equations, and Thermo Gravimetric Analysis techniques were used for characterization and particle size, specific surface areas and lattice parameters determinations were also carried out. All catalysts were used on MEAs preparation and evaluated in 5 cm 2 single cell from 25 to 100 °C at 1 atm and the best composition was also evaluated at 3 atm. In the study of metals for reactions, to reduce the platinum applied to the electrodes without performance losses, Pd/C and PdPt/C 1:1 were selected for anodes and cathodes, respectively. The developed MEA structure used 0,25 mgPt.cm -2 , showing power densities up to 550 mW.cm -2 and power of 2.2 kW net per gram of platinum. The estimated costs showed that there was a reduction of up to 64.5 %, compared to the MEA structures previously known. Depending on the temperature and operating pressure, values from US$ 1,475.30 to prepare MEAs for each installed kilowatt were obtained. Taking into account recent studies, it was concluded that the cost of the developed MEA is compatible with PEMFC stationary application

Palladium transport in SiC

Energy Technology Data Exchange (ETDEWEB)

Olivier, E.J., E-mail: jolivier@nmmu.ac.za [Centre for High Resolution Transmission Electron Microscopy, Nelson Mandela Metropolitan University, Port Elizabeth (South Africa); Neethling, J.H. [Centre for High Resolution Transmission Electron Microscopy, Nelson Mandela Metropolitan University, Port Elizabeth (South Africa)

2012-03-15

Highlights: Black-Right-Pointing-Pointer We investigate the reaction of Pd with SiC at typical HTGR operating temperatures. Black-Right-Pointing-Pointer The high temperature mobility of palladium silicides within polycrystalline SiC was studied. Black-Right-Pointing-Pointer Corrosion of SiC by Pd was seen in all cases. Black-Right-Pointing-Pointer The preferential corrosion and penetration of Pd along grain boundaries in SiC was found. Black-Right-Pointing-Pointer The penetration and transport of palladium silicides in SiC along grain boundaries was found. - Abstract: This paper reports on a transmission electron microscopy (TEM) and scanning electron microscopy (SEM) study of Pd corroded SiC. The reaction of Pd with different types of SiC at typical HTGR operating temperatures was examined. In addition the high temperature mobility of palladium silicides within polycrystalline SiC was investigated. The results indicated corrosion of the SiC by Pd in all cases studied. The corrosion leads to the formation of palladium silicides within the SiC, with the predominant phase found being Pd{sub 2}Si. Evidence for the preferential corrosion and penetration of Pd along grain boundaries in polycrystalline SiC was found. The penetration and transport, without significant corrosion, of palladium silicides into polycrystalline SiC along grain boundaries was also observed. Implications of the findings with reference to the use of Tri Isotropic particles in HTGRs will be discussed.

Performance and Long-Term Stability of Pd/PSS and Pd/Al2O3 Membranes for Hydrogen Separation.

Science.gov (United States)

Liguori, Simona; Iulianelli, Adolfo; Dalena, Francesco; Pinacci, Pietro; Drago, Francesca; Broglia, Maria; Huang, Yan; Basile, Angelo

2014-03-06

The present work is focused on the investigation of the performance and long-term stability of two composite palladium membranes under different operating conditions. One membrane (Pd/porous stainless steel (PSS)) is characterized by a ~10 µm-thick palladium layer on a porous stainless steel substrate, which is pretreated by means of surface modification and oxidation; the other membrane (Pd/Al2O3) is constituted by a ~7 µm-thick palladium layer on an asymmetric microporous Al2O3 substrate. The operating temperature and pressure ranges, used for studying the performance of these two kinds of membranes, are 350-450 °C and 200-800 kPa, respectively. The H2 permeances and the H2/N2 selectivities of both membranes were investigated and compared with literature data. At 400 °C and 200 kPa as pressure difference, Pd/PSS and Pd/Al2O3 membranes exhibited an H2/N2 ideal selectivity equal to 11700 and 6200, respectively, showing stability for 600 h. Thereafter, H2/N2 selectivity of both membranes progressively decreased and after around 2000 h, dropped dramatically to 55 and 310 for the Pd/PSS and Pd/Al2O3 membranes, respectively. As evidenced by Scanning Electron Microscope (SEM) analyses, the pinholes appear on the whole surface of the Pd/PSS membrane and this is probably due to release of sulphur from the graphite seal rings.

Inhibitory effect of Ti-Ag alloy on artificial biofilm formation.

Science.gov (United States)

Nakajo, Kazuko; Takahashi, Masatoshi; Kikuchi, Masafumi; Takada, Yukyo; Okuno, Osamu; Sasaki, Keiichi; Takahashi, Nobuhiro

2014-01-01

Titanium-silver (Ti-Ag) alloy has been improved for machinability and mechanical properties, but its anti-biofilm properties have not been elucidated yet. Thus, this study aimed to evaluate the effects of Ti-Ag alloy on biofilm formation and bacterial viability in comparison with pure Ti, pure Ag and silver-palladium (Ag-Pd) alloy. Biofilm formation on the metal plates was evaluated by growing Streptococcus mutans and Streptococcus sobrinus in the presence of metal plates. Bactericidal activity was evaluated using a film contact method. There were no significant differences in biofilm formation between pure Ti, pure Ag and Ag-Pd alloy, while biofilm amounts on Ti-20% Ag and Ti-25% Ag alloys were significantly lower (p<0.05). In addition, Ti-Ag alloys and pure Ti were not bactericidal, although pure Ag and Ag-Pd alloy killed bacteria. These results suggest that Ti-20% Ag and Ti-25% Ag alloys are suitable for dental material that suppresses biofilm formation without disturbing healthy oral microflora.

Unexpectedly high uptake of palladium by bituminous coals

Energy Technology Data Exchange (ETDEWEB)

Lakatos, J. [Research Lab. for Mining Chemistry, Hungarian Academy of Sciences, Miskolc-Egyetemvaros (Hungary); Brown, S.D.; Snape, C.E. [Univ. of Strathclyde, Dept. of Pure and Applied Chemistry, Glasgow (United Kingdom)

1997-12-31

The uptake of palladium as a conversion catalyst onto coals of different rank was investigated. Palladium fixation occurs by a different mode to that for alkaline earth and first row transition metals. Therefore, the dispersion of relatively high concentration of palladium by an ion sorption process is even possible for bituminous coals. (orig.)

Catalytic membrane in reduction of aqueous nitrates: operational principles and catalytic performance

NARCIS (Netherlands)

Ilinitch, O.M.; Cuperus, F.P.; Nosova, L.V.; Gribov, E.N.

2000-01-01

The catalytic membrane with palladium-copper active component supported over the macroporous ceramic membrane, and a series of γ-Al 2O 3 supported Pd-Cu catalysts were prepared and investigated. In reduction of nitrate ions by hydrogen in water at ambient temperature, pronounced internal diffusion

Effect of heating palladium-silver alloys on ceramic bond strength.

Science.gov (United States)

Li, Jie-yin; Li, Rui-nan; Chang, Shao-hai; Zhuang, Pei-lin; Liao, Juan-kun; Ye, Xiu-hua; Ye, Jian-tao

2015-11-01

The effects of different heat treatments on the internal oxidation and metal-ceramic bond in Pd-Ag alloys with different trace elements require further documentation. The purpose of this in vitro study was to determine whether heat treatment affects the metal-ceramic bond strength of 2 Pd-Ag alloys containing different trace elements. Thirteen cast specimens (25×3×0.5 mm) from each of 2 Pd-Ag alloy groups (W-1 and Argelite 61+3) were allocated to heat treatments before porcelain application: heating under reduced atmospheric pressure of 0.0014 MPa and 0.0026 MPa and heating under normal atmospheric pressure. Bond strengths were evaluated using a 3-point bending test according to ISO9693. Results were analyzed using 2-way ANOVA and Tukey HSD test (α=.05). Visual observation was used to determine the failure types of the fractured specimens. Scanning electron microscopy and energy dispersive spectroscopy were used to study morphologies, elemental compositions, and distributions in the specimens. The W-1 group had a mean bond strength significantly higher than that of Argelite 61+3 (PHeating under reduced atmospheric pressures of 0.0014 MPa and 0.0026 MPa resulted in similar bond strengths (P=.331), and both pressures had significantly higher bond strengths than that of heating under normal atmospheric pressure (P=.002, PHeating under different air pressures resulted in Pd-Ag alloys that contained either Sn or In and Ga, with various degrees of internal oxidation and different quantities of metallic nodules. Heating under reduced atmospheric pressure effectively improved the bond strength of the ceramic-to-Pd-Ag alloys. Copyright © 2015 Editorial Council for the Journal of Prosthetic Dentistry. Published by Elsevier Inc. All rights reserved.

Physical Properties Of Some Pd-Au-Ag Ternary Alloys: A Md Study

International Nuclear Information System (INIS)

Aydin, G.

2010-01-01

Mechanical properties of palladium (Pd), gold (Au) and silver (Ag) and their ternary alloys in the following concentrations (Au 5 0Ag 2 5Pd 2 5, Au 4 0Ag 2 0Pd 4 0) are studied by using by using molecular dynamics with Quantum Sutton-Chen (Q-SC) potential. Cell constants, densities, enthalpies, elastic constants and heat capacities are investigated. Calculations are performed in the solid phase. Rafii-Tabar combination rules are used and it is showed that these combination rules are valid for ternary alloys also. Additionally, temperature dependence of mechanical properties of alloys are investigated.

: Recyclable, ligand free palladium(II) catalyst for Heck reaction

Indian Academy of Sciences (India)

well as heterogeneous palladium catalysts, generated from either palladium(0) compounds or palladium(II) acetate or chloride salts.6 Several ligands such as phosphines, phoshites, carbenes, thioethers have been successfully employed for this reaction.7 However, homogeneous catalysis results in problems of recovery.

Molecular dynamics study of atomic displacements in disordered solid alloys

Science.gov (United States)

Puzyrev, Yevgeniy S.

The effects of atomic displacements on the energetics of alloys plays important role in the determining the properties of alloys. We studied the atomic displacements in disordered solid alloys using molecular dynamics and Monte-Carlo methods. The diffuse scattering of pure materials, copper, gold, nickel, and palladium was calculated. The experimental data for pure Cu was obtained from diffuse scattering intensity of synchrotron x-ray radiation. The comparison showed the advantages of molecular dynamics method for calculating the atomic displacements in solid alloys. The individual nearest neighbor separations were calculated for Cu 50Au50 alloy and compared to the result of XAFS experiment. The molecular dynamics method provided theoretical predictions of nearest neighbor pair separations in other binary alloys, Cu-Pd and Cu-Al for wide range of the concentrations. We also experimentally recovered the diffuse scattering maps for the Cu47.3Au52.7 and Cu85.2Al14.8 alloy.

Radioactive waste gas processing systems

International Nuclear Information System (INIS)

Kita, Kaoru; Minemoto, Masaki; Takezawa, Kazuaki.

1981-01-01

Purpose: To effectively separate and remove only hydrogen from hydrogen gas-containing radioactive waste gases produced from nuclear power plants without using large scaled facilities. Constitution: From hydrogen gas-enriched waste gases which contain radioactive rare gases (Kr, Xe) sent from the volume control tank of a chemical volume control system, only the hydrogen is separated in a hydrogen separator using palladium alloy membrane and rare gases are concentrated, volume-decreased and then stored. In this case, an activated carbon adsorption device is connected at its inlet to the radioactive gas outlet of the hydrogen separator and opened at its outlet to external atmosphere. In this system, while only the hydrogen gas permeates through the palladium alloy membrane, other gases are introduced, without permeation, into the activated carbon adsorption device. Then, the radioactive rare gases are decayed by the adsorption on the activated carbon and then released to the external atmosphere. (Furukawa, Y.)

The influence of a hyperbaric environment and increased oxygen partial pressure on the corrosion of dental alloys.

Science.gov (United States)

Mehl, Christian; Heblich, Frank; Lenz, Rudolf; Ludwig, Klaus; Kern, Matthias

2011-09-01

The purpose of this in-vitro study was to determine whether there is a correlation between a hyperbaric environment or increased oxygen partial pressure and the corrosion of dental alloys used for dental restorations in divers. Samples of three commercially available dental alloys (palladium-based, reduced-gold-content and high-gold-content) were tested in the DIN EN ISO 1562 static immersion test and the amount of dissolved ions measured by atomic absorption spectrometry. The specimens were exposed to one of the following three conditions: normobaric and normoxic conditions (PO2 21 kPa); 608 kPa (6 bar, PO2 127 kPa) pressurised air in a pressure chamber or 506 kPa (5 bar, PO2 304 kPa) pressurised nitrox in a pressure chamber. None of the exposures suggested a correlation between increased ion solubility as a measure of corrosion and increased ambient pressure of the three alloys. The reduced-gold-content alloy released zinc ions at twice the weekly recommended dose. When the palladium-based alloy was exposed to a hyperbaric or hyperbaric/hyperoxic environment, ion solubility increased only slightly for gallium and silver. Within the limited sample size of the current study it can be concluded that hyperbaric and/or hyperoxic conditions do not seem to be a risk for increased corrosion for any of the three tested alloys.

Synthesis of palladium-doped silica nanofibers by sol-gel reaction and electrospinning process

Energy Technology Data Exchange (ETDEWEB)

San, Thiam Hui; Daud, Wan Ramli Wan; Kadhum, Abdul Amir Hassan; Mohamad, Abu Bakar; Kamarudin, Siti Kartom; Shyuan, Loh Kee; Majlan, Edy Herianto [Fuel Cell Institute, Universiti Kebangsaan Malaysia, 43600 UKM Bangi, Selangor (Malaysia); Fuel Cell Institute, Universiti Kebangsaan Malaysia, 43600 UKM Bangi, Selangor, Malaysia and Department of Chemical and Process Engineering, Universiti Kebangsaan Malaysia, 43600 UKM Bangi, Selangor (Malaysia); Fuel Cell Institute, Universiti Kebangsaan Malaysia, 43600 UKM Bangi, Selangor (Malaysia)

2012-06-29

Nanofiber is drawing great attention nowadays with their high surface area per volume and flexibility in surface functionalities that make them favorable as a proton exchange membrane in fuel cell application. In this study, incorporation of palladium nanoparticles in silica nanofibers was prepared by combination of a tetraorthosilane (TEOS) sol-gel reaction with electrospinning process. This method can prevent the nanoparticles from aggregation by direct mixing of palladium nanoparticles in silica sol. The as-produced electrospun fibers were thermally treated to remove poly(vinyl pyrrolidone) (PVP) and condensation of silanol in silica framework. PVP is chosen as fiber shaping agent because of its insulting and capping properties for various metal nanoparticles. Scanning electron microscopy (SEM), energy dispersive spectrometer (EDS) and Fourier transform infrared spectroscopy (FTIR) were used to characterize the silica fibers and Pd nanoparticles on the fibers. Spun fibers with average diameter ranged from 100nm to 400nm were obtained at optimum operating condition and distribution of Pd nanoparticles on silica fibers was investigated.

Results of tritium experiments on ceramic electrolysis cells and palladium diffusers for application to fusion reactor fuel cleanup systems

International Nuclear Information System (INIS)

Carlson, R.V.; Binning, K.E.; Konishi, S.; Yoshida, H.; Naruse, Y.

1987-01-01

Tritium tests at the Tritium Systems Test Assembly have demonstrated that ceramic electrolysis cells and palladium alloy diffuser developed in Japan are possible components for a fusion reactor fuel cleanup system. Both components have been successfully operated with tritium for over a year. A failure of the first electrolysis cell was most likely the result of an over voltage on the ceramic. A simple circuit was developed to eliminate this mode of failure. The palladium diffusers tubes exhibited some degradation of mechanical properties as a result of the build up of helium from the tritium decay, after 450 days of operation with tritium, however the effects were not significant enough to affect the performance. New models of the diffuser and electrolysis cell, providing higher flow rates and more tritium compatible designs are currently being tested with tritium. 8 refs., 5 figs

Thermodynamic assessment of the palladium-tellurium (Pd-Te) system

International Nuclear Information System (INIS)

Gosse, S.; Gueneau, C.

2011-01-01

Among the fission products formed in nuclear fuels, the platinum-group metal palladium and the chalcogen element tellurium exhibit strong interaction. It is therefore of interest to be able to predict the chemical equilibria involving the Pd and Te fission products. A thermodynamic assessment is carried out using the Calphad (Calculation of Phase Diagram) method to investigate the behaviour of Pd-Te alloy system in nuclear fuels under irradiation and under waste disposal conditions. The Pd-Te binary description was optimized using experimental data found in literature including thermodynamic properties and phase diagram data. To validate the calculated phase diagram and thermodynamic properties, the results are compared with data from the literature. Both calculated and experimental phase diagrams and thermodynamic properties are in good agreement in the whole Pd-Te composition range. (authors)

Investigation of radiation-chemical behaviour of divalent palladium in perchloric acid solutions

International Nuclear Information System (INIS)

Vladimirova, M.V.; Kalinina, S.V.

1988-01-01

Gamma-radiolysis of divalent palladium in perchloric acid solutions is studied. Absorption spectra of intermediate palladium compounds formed in the irradiated solution are taken. The analysis of literature data as well as comparative analysis of the absorption spectra obtained under irradiation of palladium (2) perchloric acid solutions with absorption spectra of palladium chlorocomplexes allows to suppose that the mentioned compounds are chlorocomplexes of palladium (2) of different composition depending on HClO 4 concentration in the initial solution and absorbed radiation dose. Radiation-chemical reduction of palladium (2) up to metal is stated to take place in the whole studied range of initial concentrations of components of the system and dose rates. Kinetic dependences of metallic palladium formation are obtained. Values of radiation-chemical yields of metallic palladium formation depending on the initial concentrations of palladium (2) and perchloric acid are given. A mechanism of radiolytic reduction of palladium (2) in the investigated system is suggested based on the experimental data, and a theoretical value of the radiation-chemical yield of palladium (2) reduction being in a good agreement with experimentally found values is calculated

Preparation and characterization of a nickel/alumina composite membrane for high temperature hydrogen separation. Application in a membrane reactor for the dry reforming of methane; De la synthese d'une membrane composite nikel/ceramique permselective a l'hydrogene au reacteur membranaire. Application au reformage du methane

Energy Technology Data Exchange (ETDEWEB)

Haag, St.

2003-11-01

The objective of this work was to develop composite inorganic membranes based on nickel or palladium supported on a porous ceramic for high temperature hydrogen separation. These membranes were used in a membrane reactor for the dry reforming of methane in order to shift the chemical equilibrium towards the production of hydrogen and carbon monoxide. The metal layers were deposited on a tubular alumina support by electroless plating. The Ni and the Pd layers are 1 micron thick. The hydrogen permeation tests were done for high temperatures. The Pd/ceramic membrane is permselective to hydrogen and the H{sub 2}/N{sub 2} separation factor (single gas) is 60 at 400 deg C with a transmembrane pressure difference of 1 bar. With a gas mixture, the H{sub 2}/N{sub 2} separation factor is 13. This membrane is not completely dense and the transport mechanism of hydrogen through the Pd layer is mixed: solution-diffusion through the metal bulk and surface diffusion through the defects of the film. However, an embrittlement of the palladium layer under hydrogen atmosphere was observed at 500 deg C. The Ni/ceramic membrane is stable until 600 deg C, its permselectivity to hydrogen increases with the temperature. The use of a sweep gas can provide a H{sub 2}/N{sub 2} separation factor (mixture) of about 25. The main diffusion mechanism is surface diffusion through the pores. Both membranes are not catalytic. Thus, some catalysts composed of nickel and cobalt supported on MgO, SiO{sub 2} or Al{sub 2}O{sub 3} were prepared. These systems allow to reach theoretical limits of conversion calculated for a conventional fixed bed reactor. In the membrane reactor, an enhancement of the methane conversion (15-20%) is observed with both membranes due the selective removal of hydrogen during the reaction. The Ni/ceramic membrane more stable, more permeable and as selective as the palladium one is a brand new material for high temperature hydrogen separation. (author)

Chemical recovery of a palladium-103 from irradiated silver target

International Nuclear Information System (INIS)

Lapshina, E.V.; Kokhanyuk, V.M.; Zhuikov, B.L.; Myasoedova, G.V.; Zakhartchenko, E.A.; Phillips, D.R.; Jamriska, D.J.

2003-01-01

The goal of this work is to develop an extraction method of no-carrier-added palladium-103 from silver. Metallic silver targets were irradiated by protons with the energy of 60-140 MeV to generate palladium-103. Other radioactive isotopes of rhodium, ruthenium, technetium, palladium and silver are also formed at the same time. Two methods of Pd-103 recovering from irradiated silver target are considered. The first one includes the dissolving of the irradiated silver target in nitric acid followed by adding of hydrochloric acid to the solution. Palladium with rhodium, ruthenium and technetium completely remained in solution while silver was precipitated in the form of silver chloride. Extraction of palladium from the obtained solution was provided by the formation of palladium complex with a chelate sorbent which is specific to palladium in acidic solutions. The sorbent makes it possible to separate palladium from admixtures of rhodium, ruthenium and technetium isotopes. The polymeric complex-forming sorbent of fibrous structure with the groups of 3 (5) - methylpyrazole (POLYORGS-15n) is used. An other possible method has been also studied. It includes again dissolving of metallic silver in nitric acid, but does not need silver chloride precipitation. Silver may be sorbed by the complex-forming sorbents, but its sorption is very sensitive to acid concentration. Chelate sorbents of fibrous structure with the groups of amidoxime and hydrazidine (POLYORGS-33n) have been successfully used in our experiments. A high efficiency of palladium extraction by POLYORGS-33n from 2-4 M nitric acid solutions was achieved. Concentrated hydrochloric acid (without heating) was used for palladium desorption with higher yield than in the first method. (authors)

Palladium Nanoparticle Hydrogen Sensor

Directory of Open Access Journals (Sweden)

I. Pavlovsky

2006-12-01

Full Text Available An innovative hydrogen sensor based on palladium (Pd nanoparticle networks is described in the article. Made by Applied Nanotech Inc. sensor has a fast response time, in the range of seconds, which is increased at 80 °C due to higher hydrogen diffusion rates into the palladium lattice. The low detection limit of the sensor is 10 ppm of H2, and the high limit is 40,000 ppm. This is 100% of a lowest flammability level of hydrogen. This range of sensitivities complies with the requirements that one would expect for a reliable hydrogen sensor.

Atomistic simulation of helium bubble nucleation in palladium

Energy Technology Data Exchange (ETDEWEB)

Wang Liang [Department of Applied Physics, Hunan University, Changsha 410082 (China); Hu, Wangyu [Department of Applied Physics, Hunan University, Changsha 410082 (China)], E-mail: wangyuhu2001cn@yahoo.com.cn; Xiao Shifang [Department of Applied Physics, Hunan University, Changsha 410082 (China)], E-mail: sfxiao@yahoo.com.cn; Yang Jianyu [Department of Maths and Physics, Hunan Institute of Engineering, Xiangtan 411104 (China); Deng Huiqiu [Department of Applied Physics, Hunan University, Changsha 410082 (China)

2009-09-15

A palladium crystal has been constructed with 11808 atoms. 55 helium atoms occupied the octahedral position of palladium crystal are introduced and retained in a spherical region. Molecular dynamic simulations are performed in a constant temperature and constant volume ensemble (NVT) with temperature controlled by Nose-Hoover thermostat. The interactions between palladium atoms are described with modified analytic embedded atom method (MAEAM), the interactions between palladium atom and helium atom are in the form of Morse potential, and the interactions between helium atoms are in the form of L-J potential function. With the analysis of the radial distribution function (RDF) and microstructure, it reveals that some of helium atoms form a series of clusters with different size, and the nucleation core is random at low temperature, and which is the embryo of helium bubble. Increasing temperature can accelerate the process of bubble nucleation, and the clusters will aggregate and coalesce into a bigger one in which there are no palladium atoms, and it is considered as a helium bubble.

Nested Fermi surfaces and order in the rare earth nickel borocarbides and copper palladium alloys

International Nuclear Information System (INIS)

Wilkinson, Ian

2002-01-01

The electronic structure of two systems, each displaying a different type of order believed to derive from their respective Fermi surface topologies, has been investigated using the two-dimensional angular correlation of annihilation radiation (2D-ACAR) technique. A particular topological feature of a generic rare earth nickel borocarbide (general formula RNi 2 B 2 C) Fermi surface is popularly believed to be responsible for a particular modulated arrangement of local moments observed in several magnetic borocarbides. Accordingly, c-axis 2D-ACAR spectra were collected from four representative members of the series, namely the Er, Tm, Yb and Lu compounds. A further a-axis projection from LuNi 2 B 2 C provides an additional comparison with electronic structure calculations performed for this compound. The c-axis projected k-space electron occupancies reveal a fundamentally similar Fermi surface topology across the measured compounds. The a- and c-axis k-space occupancies obtained from LuNi 2 B 2 C showed exceptional qualitative agreement with the corresponding calculated electron occupancy. A number of edge-detection methods were employed to identify the projected Fermi surface, and the existence of the proposed feature was confirmed by direct observation in each of the measured compounds. Calipers of this feature were found to be in good general agreement with those predicted by relevant calculation and expected from indirect experimental evidence. The compositional phase behaviour of copper-palladium solid solutions is believed to be strongly influenced by the shape of their respective Fermi surfaces. In particular, the concentration-dependent positions of diffuse peaks in electron and X-ray diffraction patterns from disordered samples has been associated with the corresponding evolution of flat, parallel areas on the alloy Fermi surface. Electronic structure calculations indicate these areas to be maximal around 40 at. % Pd, and it has been further suggested that

SEPARATION OF HYDROGEN AND CARBON DIOXIDE USING A NOVEL MEMBRANE REACTOR IN ADVANCED FOSSIL ENERGY CONVERSION PROCESS

Energy Technology Data Exchange (ETDEWEB)

Shamsuddin Ilias

2005-02-03

Inorganic membrane reactors offer the possibility of combining reaction and separation in a single operation at high temperatures to overcome the equilibrium limitations experienced in conventional reactor configurations. Such attractive features can be advantageously utilized in a number of potential commercial opportunities, which include dehydrogenation, hydrogenation, oxidative dehydrogenation, oxidation and catalytic decomposition reactions. However, to be cost effective, significant technological advances and improvements will be required to solve several key issues which include: (a) permselective thin solid film, (b) thermal, chemical and mechanical stability of the film at high temperatures, and (c) reactor engineering and module development in relation to the development of effective seals at high temperature and high pressure. In this project, we are working on the development and application of palladium and palladium-silver alloy thin-film composite membranes in membrane reactor-separator configuration for simultaneous production and separation of hydrogen and carbon dioxide at high temperature. From our research on Pd-composite membrane, we have demonstrated that the new membrane has significantly higher hydrogen flux with very high perm-selectivity than any of the membranes commercially available. The steam reforming of methane by equilibrium shift in Pd-composite membrane reactor is being studied to demonstrate the potential application of this new development. A two-dimensional, pseudo-homogeneous membrane-reactor model was developed to investigate the steam-methane reforming (SMR) reactions in a Pd-based membrane reactor. Radial diffusion was taken into consideration to account for the concentration gradient in the radial direction due to hydrogen permeation through the membrane. With appropriate reaction rate expressions, a set of partial differential equations was derived using the continuity equation for the reaction system. The equations were

Les réacteurs à membranes : possibilités d'application dans l'industrie pétrolière et pétrochimique Membrane Reactors: Possibilities of Application in the Petroleum and Petrochemical Industry

Directory of Open Access Journals (Sweden)

Guy C.

2006-11-01

Full Text Available Cet article fait le point sur l'état de la recherche dans le domaine des réacteurs chimiques avec séparation par membrane intégrée et de leur applications dans le domaine du raffinage et de la pétrochimie. Trois applications potentiellement intéressantes sont identifiées et, pour chacune, les avantages de l'utilisation d'un réacteur à membrane sont discutés. Ce sont : la déshydrogénation du propane en propylène, la déshydrogénation d'un naphtène cyclohexanique et le vaporéformage du gaz naturel. Pour ces réactions, les membranes à base de palladium apparaissent les plus performantes compte tenu de leur tenue en température, de leur sélectivité et de leur perméabilité à l'hydrogène. Quelques éléments relatifs à leur développement sont présentés en conclusion. Recently, the use of membrane in reaction engineering has been more and more advocated. The selective separation of the products from the reaction mixture allows to achieve higher conversion or better selectivity or to operate under less severe conditions or with smaller units. This paper presents an update on the recent advances in the field of chemical membrane reactors and on their applications in refining and petrochemistry. Previous work. Most of the possible applications of membrane reactors in petroleum and petrochemical industry concern gaseous catalytic reactions. For this reason, gas permeation membranes are the primary component of membrane reactors. Gas permeation membranes present different types of physical structure : dense, microporous or asymmetric which is a combination of the two. Separating properties of dense membranes are function of the solubility and diffusivity of each gaseous component in the membrane material. For microporous membranes, they follow four mechanisms : Knudsen diffusion, surface diffusion, capillary condensation or molecular sieving. Although organic polymers are the common constituent of gas permeation membrane, their

New Fuel Alloys Seeking Optimal Solidus and Phase Behavior for High Burnup and TRU Burning

International Nuclear Information System (INIS)

Blackwood, V.S.; Jones, Z.S.; Olson, D.L.; Mishra, B.; Mariani, R.D.; Porter, D.L.; Kennedy, J.R.; Hayes, S.L.

2013-01-01

Summary: • Pd will bind lanthanide fission products. • 2 wt% Pd in alloy is expected to allow 20 at% Heavy Metal burnup, 4 wt% Pd possibly 30-40 at% HM burnup. • For recycled fuel with some lanthanide carryover, palladium additive will also prevent premature FCCI. • Novel uranium alloy systems suitable for burning transuranics were identified. • U-Mo-Ti-Zr and U-W-Mo irradiations may perform comparably to U-10Zr, but the real tests needed must include Pu and Np for TRU burning. – Diffusion couples with alloys and Fe or cladding; – Irradiations

Hydrogen Production via Steam Reforming of Ethyl Alcohol over Palladium/Indium Oxide Catalyst

Directory of Open Access Journals (Sweden)

Tetsuo Umegaki

2009-01-01

Full Text Available We report the synergetic effect between palladium and indium oxide on hydrogen production in the steam reforming reaction of ethyl alcohol. The palladium/indium oxide catalyst shows higher hydrogen production rate than indium oxide and palladium. Palladium/indium oxide affords ketonization of ethyl alcohol with negligible by-product carbon monoxide, while indium oxide mainly affords dehydration of ethyl alcohol, and palladium affords decomposition of ethyl alcohol with large amount of by-product carbon monoxide. The catalytic feature of palladium/indium oxide can be ascribed to the formation of palladium-indium intermetallic component during the reaction as confirmed by X-ray diffraction and X-ray photoelectron spectroscopic measurements.

Fabrication of palladium-based microelectronic devices by microcontact printing

International Nuclear Information System (INIS)

Wolfe, Daniel B.; Love, J. Christopher; Paul, Kateri E.; Chabinyc, Michael L.; Whitesides, George M.

2002-01-01

This letter demonstrates the patterning of thin films of metallic palladium by microcontact printing (μCP) of octadecanethiol, and the use of the patterned films in the fabrication of a functional sensor. This technique was also used to prepare templates of palladium for the electroless deposition of copper. The resistivity of the palladium and copper microstructures was 13.8 and 2.8 μΩ cm, respectively; these values are approximately 40% larger than the values for the pure bulk metals. Palladium patterned into serpentine wires using μCP functioned as a hydrogen sensor with sensitivity of 0.03 vol % H 2 in N 2 , and a response time of ∼10 s (at room temperature)

Co-current and counter-current configurations for ethanol steam reforming in a dense Pd-Ag membrane reactor

NARCIS (Netherlands)

Gallucci, F.; de Falco, M.; Tosti, S.; Marrelli, L; Basile, A.

2008-01-01

The ethanol steam-reforming reaction to produce pure hydrogen has been studied theoretically. A mathematical model has been formulated for a traditional system and a palladium membrane reactor packed with a Co-based catalyst and the simulation results related to the membrane reactor for both

Palladium-based electrocatalysts for ethanol oxidation reaction in DEFC; Eletrocatalisadores de paladio para reacao de oxidacao do etanol em DEFC

Energy Technology Data Exchange (ETDEWEB)

Moraes, L.P.R. de; Elsheikh, A.; Silva, E. L. da; Radtke, C.; Amico, S.C.; Malfatti, C.F., E-mail: leticiaprm@gmail.com [Universidade Federal do Rio Grande do Sul (UFRGS), Porto Alegre, RS (Brazil)

2014-07-01

Direct ethanol fuel cells require the use of electrocatalysts to promote bond cleavage of the ethanol molecule in an efficient way. Currently, most electrocatalysts contain platinum, which enables improved catalytic activity and stability in acidic media. However platinum presents high cost and low availability. Based on that, novel catalysts have been developed, such as those based on palladium and its alloys, which have attained excellent results in the oxidation of ethanol in alkaline media. In this work, Pd, PdSn and PdNiSn catalysts supported on Vulcan XC72R carbon were synthesized via impregnation/reduction. The electrocatalysts were characterized by RBS, XRD and cyclic voltammetry. The X-ray diffraction results showed the formation of an alloy and not the deposition of isolated elements. The synthesized catalysts displayed good catalytic activity, as observed by cyclic voltammetry, being the best electrochemical performance achieved by the ternary alloy. (author)

Silver-Palladium Surfaces Inhibit Biofilm Formation

DEFF Research Database (Denmark)

Chiang, Wen-Chi; Schroll, Casper; Hilbert, Lisbeth Rischel

2009-01-01

Undesired biofilm formation is a major concern in many areas. In the present study, we investigated biofilm-inhibiting properties of a silver-palladium surface that kills bacteria by generating microelectric fields and electrochemical redox processes. For evaluation of the biofilm inhibition...... efficacy and study of the biofilm inhibition mechanism, the silver-sensitive Escherichia coli J53 and the silver-resistant E. coli J53[pMG101] strains were used as model organisms, and batch and flow chamber setups were used as model systems. In the case of the silver-sensitive strain, the silver......-palladium surfaces killed the bacteria and prevented biofilm formation under conditions of low or high bacterial load. In the case of the silver-resistant strain, the silver-palladium surfaces killed surface-associated bacteria and prevented biofilm formation under conditions of low bacterial load, whereas under...

The solubility of palladium(II) bis-dimethylglyoximate

International Nuclear Information System (INIS)

Maghzian, R.

1978-01-01

The solubility of palladium(II) bis-dimethylglyoximate in different solutions has been determined. Values obtained for the solubility of the palladium complex are tabulated. The solubility is the lowest in water, ammonium acetate and a 25% acetone-water mixture. It is highest in dilute HCl and acetone but precipitation from aqueous acetone should be satisfactory for most purposes if the acetone content of the solvent is roughly less than 50% by volume. The solubility in dilute HCl reflects the concern by previous workers for losses in precipitation from mineral acid. In general, however, the losses are unlikely to be significant unless the quantity of palladium to be precipitated and weighed is small. (T.G.)

Determination of palladium by flame photometry

International Nuclear Information System (INIS)

Parellada Bellod, R.

1964-01-01

A study on the determination of palladium by lame photometry, fixing the most convent experimental conditions and using solvents to increase the emission of this elements is carried out. Among the organic solvents, acetone has been found the most efficient. The interferences produced by anions and cations have also been studied and an analytical method is related, in which lines of calibration of 0 to 100 ppm palladium re used. (Author) 7 refs

Adsorption of palladium ions by modified carbons from rice husks

International Nuclear Information System (INIS)

Mostafa, M.R.

1994-01-01

Steam activated carbon of high surface area does not show palladium ions adsorption. Treatment of this carbon with HF acid increases to a great extent the gas adsorption capacity expressed as nitrogen surface area as well as the adsorption capacity of palladium ions from aqueous solution. HHB was loaded in different amounts on to these carbons. The acid sites represent the active fraction of the surface on which the adsorption palladium ions proceed. The uptake of palladium ions by HHB treated carbons is related to the total number of HHB molecules loaded on the carbon surface. (author)

Reforming of Liquid Hydrocarbons in a Novel Hydrogen-Selective Membrane-Based Fuel Processor

Energy Technology Data Exchange (ETDEWEB)

Shamsuddin Ilias

2006-03-10

In this work, asymmetric dense Pd/porous stainless steel composite membranes were fabricated by depositing palladium on the outer surface of the tubular support. The electroless plating method combined with an osmotic pressure field was used to deposit the palladium film. Surface morphology and microstructure of the composite membranes were characterized by SEM and EDX. The SEM and EDX analyses revealed strong adhesion of the plated pure palladium film on the substrate and dense coalescence of the Pd film. Membranes were further characterized by conducting permeability experiments with pure hydrogen, nitrogen, and helium gases at temperatures from 325 to 450 C and transmembrane pressure differences from 5 to 45 psi. The permeation results showed that the fabricated membranes have both high hydrogen permeability and selectivity. For example, the hydrogen permeability for a composite membrane with a 20 {micro}m Pd film was 3.02 x 10{sup -5} moles/m{sup 2}.s.Pa{sup 0.765} at 450 C. Hydrogen/nitrogen selectivity for this composite membrane was 1000 at 450 C with a transmembrane pressure difference of 14.7 psi. Steam reforming of methane is one of the most important chemical processes in hydrogen and syngas production. To investigate the usefulness of palladium-based composite membranes in membrane-reactor configuration for simultaneous production and separation of hydrogen, steam reforming of methane by equilibrium shift was studied. The steam reforming of methane using a packed-bed inert membrane tubular reactor (PBIMTR) was simulated. A two-dimensional pseudo-homogeneous reactor model with parallel flow configuration was developed for steam reforming of methane. The shell volume was taken as the feed and sweep gas was fed to the inside of the membrane tube. Radial diffusion was taken into account for concentration gradient in the radial direction due to hydrogen permeation through the membrane. With appropriate reaction rate expressions, a set of partial differential

Dendritic surface morphology of palladium hydride produced by electrolytic deposition

International Nuclear Information System (INIS)

Julin, Peng; Bursill, L.A.

1990-01-01

Conventional and high-resolution electron microscopic studies of electrolytically-deposited palladium hydride reveal a fascinating variety of surface profile morphologies. The observations provide direct information concerning the surface structure of palladium electrodes and the mechanism of electrolytic deposition of palladium black. Both classical electrochemical mechanisms and recent 'modified diffusion-limited-aggregation' computer simulations are discussed in comparison with the experimental results. 13 refs., 9 figs

ENHANCEMENT OF EQUILIBRIUMSHIFT IN DEHYDROGENATION REACTIONS USING A NOVEL MEMBRANE REACTOR; FINAL

International Nuclear Information System (INIS)

Shamsuddin Ilias, Ph.d., P.E.; Franklin G. King, D.Sc.

2001-01-01

With the advances in new inorganic materials and processing techniques, there has been renewed interest in exploiting the benefits of membranes in many industrial applications. Inorganic and composite membranes are being considered as potential candidates for use in membrane-reactor configuration for effectively increasing reaction rate, selectivity and yield of equilibrium limited reactions. To investigate the usefulness of a palladium-ceramic composite membrane in a membrane reactor-separator configuration, we investigated the dehydrogenation of cyclohexane by equilibrium shift. A two-dimensional pseudo-homogeneous reactor model was developed to study the dehydrogenation of cyclohexane by equilibrium shift in a tubular membrane reactor. Radial diffusion was considered to account for the concentration gradient in the radial direction due to permeation through the membrane. For a dehydrogenation reaction, the feed stream to the reaction side contained cyclohexane and argon, while the separation side used argon as the sweep gas. Equilibrium conversion for dehydrogenation of cyclohexane is 18.7%. The present study showed that 100% conversion could be achieved by equilibrium shift using Pd-ceramic membrane reactor. For a feed containing cyclohexane and argon of 1.64 x 10(sup -6) and 1.0 x 10(sup -3) mol/s, over 98% conversion could be readily achieved. The dehydrogenation of cyclohexane was also experimentally investigated in a palladium-ceramic membrane reactor. The Pd-ceramic membrane was fabricated by electroless deposition of palladium on ceramic substrate. The performance of Pd-ceramic membrane was compared with a commercially available hydrogen-selective ceramic membrane. From limited experimental data it was observed that by appropriate choice of feed flow rate and sweep gas rate, the conversion of cyclohexane to benzene and hydrogen can increased to 56% at atmospheric pressure and 200 C in a Pd-ceramic membrane reactor. In the commercial ceramic membrane

Influence of adsorbed carbon dioxide on hydrogen electrosorption in palladium-platinum-rhodium alloys

International Nuclear Information System (INIS)

Lukaszewski, M.; Grden, M.; Czerwinski, A.

2004-01-01

Carbon dioxide electroreduction was applied to examine the processes of hydrogen electrosorption (adsorption, absorption and desorption) by thin electrodeposits of Pd-Pt-Rh alloys under conditions of cyclic voltammetric (CV) experiments. Due to different adsorption characteristics towards the adsorption product of the electroreduction of CO 2 (reduced CO 2 ) exhibited by the alloy components hydrogen adsorption and hydrogen absorption signals can be distinguished on CV curves. Reduced CO 2 causes partial blocking of hydrogen adsorbed on surface Pt and Rh atoms, without any significant effect on hydrogen absorption into alloy. It reflects the fact that adsorbed hydrogen bonded to Pd atoms does not participate in CO 2 reduction, while hydrogen adsorbed on Pt and Rh surface sites is inactive in the absorption reaction. In contrast, CO is adsorbed on all alloy components and causes a marked inhibition of hydrogen sorption (both adsorption and absorption)/desorption reactions

Fexofenadine Suppresses Delayed-Type Hypersensitivity in the Murine Model of Palladium Allergy

Directory of Open Access Journals (Sweden)

Ryota Matsubara

2017-06-01

Full Text Available Palladium is frequently used in dental materials, and sometimes causes metal allergy. It has been suggested that the immune response by palladium-specific T cells may be responsible for the pathogenesis of delayed-type hypersensitivity in study of palladium allergic model mice. In the clinical setting, glucocorticoids and antihistamine drugs are commonly used for treatment of contact dermatitis. However, the precise mechanism of immune suppression in palladium allergy remains unknown. We investigated inhibition of the immune response in palladium allergic mice by administration of prednisolone as a glucocorticoid and fexofenadine hydrochloride as an antihistamine. Compared with glucocorticoids, fexofenadine hydrochloride significantly suppressed the number of T cells by interfering with the development of antigen-presenting cells from the sensitization phase. Our results suggest that antihistamine has a beneficial effect on the treatment of palladium allergy compared to glucocorticoids.

Palladium-Catalyzed Cross-Coupling Reactions of Perfluoro Organic Compounds

Directory of Open Access Journals (Sweden)

Masato Ohashi

2014-09-01

Full Text Available In this review, we summarize our recent development of palladium(0-catalyzed cross-coupling reactions of perfluoro organic compounds with organometallic reagents. The oxidative addition of a C–F bond of tetrafluoroethylene (TFE to palladium(0 was promoted by the addition of lithium iodide, affording a trifluorovinyl palladium(II iodide. Based on this finding, the first palladium-catalyzed cross-coupling reaction of TFE with diarylzinc was developed in the presence of lithium iodide, affording α,β,β-trifluorostyrene derivatives in excellent yield. This coupling reaction was expanded to the novel Pd(0/PR3-catalyzed cross-coupling reaction of TFE with arylboronates. In this reaction, the trifluorovinyl palladium(II fluoride was a key reaction intermediate that required neither an extraneous base to enhance the reactivity of organoboronates nor a Lewis acid additive to promote the oxidative addition of a C–F bond. In addition, our strategy utilizing the synergetic effect of Pd(0 and lithium iodide could be applied to the C–F bond cleavage of unreactive hexafluorobenzene (C6F6, leading to the first Pd(0-catalyzed cross-coupling reaction of C6F6 with diarylzinc compounds.

Preparation and characterization of nanodiamond cores coated with a thin Ni-Zn-P alloy film

International Nuclear Information System (INIS)

Wang Rui; Ye Weichun; Ma Chuanli; Wang Chunming

2008-01-01

Nanodiamond cores coated with a thin Ni-Zn-P alloy film were prepared by an electroless deposition method under the conditions of tin chloride sensitization and palladium chloride activation. The prepared materials were analyzed by Fourier transform infrared (FTIR) spectrometry and X-ray diffraction (XRD). The nanostructure of the materials was then characterized by transmission electron microscopy (TEM). The alloy film composition was characterized by Energy Dispersive X-ray (EDX) analysis. The results indicated the approximate composition 49.84%Ni-37.29%Zn-12.88%P was obtained

Enhancing the performance of single-chambered microbial fuel cell using manganese/palladium and zirconium/palladium composite cathode catalysts.

Science.gov (United States)

Jadhav, Dipak A; Deshpande, Parag A; Ghangrekar, Makarand M

2017-08-01

Application of ZrO 2 , MnO 2 , palladium, palladium-substituted-zirconium oxide (Zr 0.98 Pd 0.02 O 2 ) and palladium-substituted-manganese oxide (Mn 0.98 Pd 0.02 O 2 ) cathode catalysts in a single-chambered microbial fuel cell (MFC) was explored. The highest power generation (1.28W/m 3 ) was achieved in MFC with Mn 0.98 Pd 0.02 O 2 catalyst, which was higher than that with MnO 2 (0.58W/m 3 ) alone; whereas, MFC having Zr 0.98 Pd 0.02 O 2 catalyzed cathode and non-catalyzed cathode produced powers of 1.02 and 0.23W/m 3 , respectively. Also, low-cost zirconium-palladium-composite showed better catalytic activity and capacitance over ZrO 2 with 20A/m 3 current production and demonstrated its suitability for MFC applications. Cyclic voltammetry analyses showed higher well-defined redox peaks in composite catalysts (Mn/Zr-Pd-C) over other catalyzed MFCs containing MnO 2 or ZrO 2 . Electrochemical behaviour of composite catalysts on cathode showed higher availability of adsorption sites for oxygen reduction and, hence, enhanced the rate of cathodic reactions. Thus, Mn/Zr-Pd-C-based composite catalysts exhibited superior cathodic performance and could be proposed as alternatives to costly Pd-catalyst for field applications. Copyright © 2017 Elsevier Ltd. All rights reserved.

Facile synthesis of bacitracin-templated palladium nanoparticles with superior electrocatalytic activity

Science.gov (United States)

Li, Yanji; Wang, Zi; Li, Xiaoling; Yin, Tian; Bian, Kexin; Gao, Faming; Gao, Dawei

2017-02-01

Palladium nanomaterials have attracted great attention on the development of electrocatalysts for fuel cells. Herein, we depicted a novel strategy in the synthesis of palladium nanoparticles with superior electrocatalytic activity. The new approach, based on the self-assembly of bacitracin biotemplate and palladium salt for the preparation of bacitracin-palladium nanoparticles (Bac-PdNPs), was simple, low-cost, and green. The complex, composed by a series of spherical Bac-PdNPs with a diameter of 70 nm, exhibited a chain-liked morphology in TEM and a face-centered cubic crystal structure in X-Ray diffraction and selected area electron diffraction. The palladium nanoparticles were mono-dispersed and stable in aqueous solution as shown in TEM and zeta potential. Most importantly, compared to the commercial palladium on carbon (Pd/C) catalyst (8.02 m2 g-1), the Bac-PdNPs showed a larger electrochemically active surface area (47.57 m2 g-1), which endowed the products an excellent electrocatalytic activity for ethanol oxidation in alkaline medium. The strategy in synthesis of Bac-PdNPs via biotemplate approach might light up new ideas in anode catalysts for direct ethanol fuel cells.

Amorphous metallic alloys for oxygen reduction reaction in a polymer electrolyte membrane fuel cell

Energy Technology Data Exchange (ETDEWEB)

Gonzalez-Huerta, R.; Guerra-Martinez, I.; Lopez, J.S. [Inst. Politecnico Nacional, ESIQIE, Mexico City (Mexico). Lab. de Electroquimica; Pierna, A.R. [Basque Country Univ., San Sebastian (Spain). Dept. of Chemical Engineering and Environment; Solorza-Feria, O. [Inst. Politenico Nacional, Centro de Investigacion y de Estudios Avanzados, Mexico City (Mexico). Dept. de Quimica

2010-07-15

Direct methanol fuel cells (DMFC) and polymer electrolyte membrane fuel cells (PEMFC) represent an important, environmentally clean energy source. This has motivated extensive research on the synthesis, characterization and evaluation of novel and stable oxygen reduction electrocatalysts for the direct four-electron transfer process to water formation. Studies have shown that amorphous alloyed compounds can be used as electrode materials in electrochemical energy conversion devices. Their use in PEMFCs can optimize the electrocatalyst loading in the membrane electrode assembly (MEA). In this study, amorphous metallic PtSn, PtRu and PtRuSn alloys were synthesized by mechanical milling and used as cathodes for the oxygen reduction reaction (ORR) in sulphuric acid and in a single PEM fuel cell. Two different powder morphologies were observed before and after the chemical activation in a hydrofluoric acid (HF) solution at 25 degrees C. The kinetics of the ORR on the amorphous catalysts were investigated. The study showed that the amorphous metallic PtSn electrocatalyst was the most active of the 3 electrodes for the cathodic reaction. Fuel cell experiments were conducted at various temperatures at 30 psi for hydrogen (H{sub 2}) and at 34 psi for oxygen (O{sub 2}). MEAs made of Nafion 115 and amorphous metallic PtSn dispersed on carbon powder in a PEMFC had a power density of 156 mW per cm{sup 2} at 0.43V and 80 degrees C. 12 refs., 1 tab., 5 figs.

Porous palladium coated conducting polymer nanoparticles for ultrasensitive hydrogen sensors

Science.gov (United States)

Lee, Jun Seop; Kim, Sung Gun; Cho, Sunghun; Jang, Jyongsik

2015-12-01

Hydrogen, a clean-burning fuel, is of key importance to various industrial applications, including fuel cells and in the aerospace and automotive industries. However, hydrogen gas is odorless, colorless, and highly flammable; thus appropriate safety protocol implementation and monitoring are essential. Highly sensitive hydrogen leak detection and surveillance sensor systems are needed; additionally, the ability to maintain uniformity through repetitive hydrogen sensing is becoming increasingly important. In this report, we detail the fabrication of porous palladium coated conducting polymer (3-carboxylate polypyrrole) nanoparticles (Pd@CPPys) to detect hydrogen gas. The Pd@CPPys are produced by means of facile alkyl functionalization and chemical reduction of a pristine 3-carboxylate polypyrrole nanoparticle-contained palladium precursor (PdCl2) solution. The resulting Pd@CPPy-based sensor electrode exhibits ultrahigh sensitivity (0.1 ppm) and stability toward hydrogen gas at room temperature due to the palladium sensing layer.Hydrogen, a clean-burning fuel, is of key importance to various industrial applications, including fuel cells and in the aerospace and automotive industries. However, hydrogen gas is odorless, colorless, and highly flammable; thus appropriate safety protocol implementation and monitoring are essential. Highly sensitive hydrogen leak detection and surveillance sensor systems are needed; additionally, the ability to maintain uniformity through repetitive hydrogen sensing is becoming increasingly important. In this report, we detail the fabrication of porous palladium coated conducting polymer (3-carboxylate polypyrrole) nanoparticles (Pd@CPPys) to detect hydrogen gas. The Pd@CPPys are produced by means of facile alkyl functionalization and chemical reduction of a pristine 3-carboxylate polypyrrole nanoparticle-contained palladium precursor (PdCl2) solution. The resulting Pd@CPPy-based sensor electrode exhibits ultrahigh sensitivity (0.1 ppm

Methanol oxidation reaction on core-shell structured Ruthenium-Palladium nanoparticles: Relationship between structure and electrochemical behavior

Science.gov (United States)

Kübler, Markus; Jurzinsky, Tilman; Ziegenbalg, Dirk; Cremers, Carsten

2018-01-01

In this work the relationship between structural composition and electrochemical characteristics of Palladium(Pd)-Ruthenium(Ru) nanoparticles during alkaline methanol oxidation reaction is investigated. The comparative study of a standard alloyed and a precisely Ru-core-Pd-shell structured catalyst allows for a distinct investigation of the electronic effect and the bifunctional mechanism. Core-shell catalysts benefit from a strong electronic effect and an efficient Pd utilization. It is found that core-shell nanoparticles are highly active towards methanol oxidation reaction for potentials ≥0.6 V, whereas alloyed catalysts show higher current outputs in the lower potential range. However, differential electrochemical mass spectrometry (DEMS) experiments reveal that the methanol oxidation reaction on core-shell structured catalysts proceeds via the incomplete oxidation pathway yielding formaldehyde, formic acid or methyl formate. Contrary, the alloyed catalyst benefits from the Ru atoms at its surface. Those are found to be responsible for high methanol oxidation activity at lower potentials as well as for complete oxidation of CH3OH to CO2 via the bifunctional mechanism. Based on these findings a new Ru-core-Pd-shell-Ru-terrace catalyst was synthesized, which combines the advantages of the core-shell structure and the alloy. This novel catalyst shows high methanol electrooxidation activity as well as excellent selectivity for the complete oxidation pathway.

Thermosonic wire bonding of IC devices using palladium wire

International Nuclear Information System (INIS)

Shze, J.H.; Poh, M.T.; Tan, R.M.

1996-01-01

The feasibility of replacing gold wire by palladium wire in thermosonic wire bonding of CMOS and bipolar devices are studied in terms of the manufacturability, physical, electrical and assembly performance. The results that palladium wire is a viable option for bonding the bipolar devices but not the CMOS devices

Novel palladium-lead (Pd-Pb/C) bimetallic catalysts for electrooxidation of ethanol in alkaline media

Energy Technology Data Exchange (ETDEWEB)

Wang, Yi; Nguyen, Truong Son; Wang, Xin [School of Chemical and Biomedical Engineering, Nanyang Technological University, Singapore 639798 (Singapore); Liu, Xuewei [School of Physical and Mathematical Sciences, Nanyang Technological University, Singapore 639798 (Singapore)

2010-05-01

Carbon-supported bimetallic palladium-lead (Pd-Pb/C) catalysts with different amounts of lead are prepared using a co-reduction method. The catalysts are characterized by various techniques, which reveal the formation of an alloy nanoparticle structure. The electrochemical activities of the catalysts towards ethanol oxidation in alkaline media are examined by cyclic voltammetry, linear sweep voltammetry and chronoamperometry methods. The results show that the Pd-Pb(4:1)/C catalyst exhibits a better catalytic activity than the Pd/C catalyst. From carbon monoxide (CO) stripping results, the addition of lead also facilitates the oxidative removal of adsorbed CO. The promoting effect of lead is explained by a bi-functional mechanism and d-band theory. (author)

Chemical recovery of palladium-103 from irradiated silver target

International Nuclear Information System (INIS)

Lapshina, E.V.; Kokhanyuk, V.M.; Zhuikov, B.L.; Myasoedova, G.V.; Zakhartchenko, E.A.; Phillips, D.R.; Jamriska, D.J.

2003-01-01

The goal of this work is to develop an extraction method of no-carrier-added palladium-103 from silver. Metallic silver targets may be irradiated by protons with energy of 60-200 MeV or more to generate palladium-103 simultaneously with other radioactive isotopes of rhodium, ruthenium, technetium, palladium and silver. According to the dependence experimental production yield of Pd-103 and isotopes of other elements in thick silver target vs. Proton energy the most suitable energy for maximum yield of Pd-103 and minimum yield of other elements is from about 100 to about 140 MeV. Activity of radionuclides produced in silver target depends from many factors (target thickness, irradiation time, etc.). Two methods of Pd-103 recovering from irradiated silver target are considered in this work: (1) Silver target is dissolved in nitric acid followed by silver precipitation in the form of silver chloride by addition of HCl. The solution containing Pd, Rh and other radionuclides is passed through the layer of fibrous sorbent POLYORGS-15n. Then the sorbent is washed and Pd is desorbed by hot 12 M hydrochloric acid; (2) Silver target is dissolved in nitric acid followed by passing of the obtained solution (2 M HNO 3 ) through a disk set of complex forming sorbent POLYORGS-33n. Under these conditions palladium is sorbed by the sorbent while silver, rhodium, ruthenium and technetium are passed through the sorbent. Then the sorbent is washed with 2M nitric acid, and Pd is desorbed by 12 M hydrochloric acid. Extraction of palladium is occurred during the formation of palladium complex with a chelate sorbent specific to palladium in acidic solutions. Such a sorbent makes possible separation of palladium from accompanying radionuclides such as rhodium, ruthenium and technetium. The polymeric complex-forming sorbent of fibrous structure with the groups of 3(5)-methylpyrazole (POLYORGS-15) is used. The distinctive feature of the sorbents in the form of fibrous 'filled' material is

Thermophysical Properties of Matter - the TPRC Data Series. Volume 12. Thermal Expansion Metallic Elements and Alloys

Science.gov (United States)

1975-01-01

the thermal expansion of metallic elements, alloys, and intermetallic compounds. We believe there is also much food for reflection by the specialist...24 39 Plutonium Pu ........ ............... 260 40’ t Polonium Po ..... ............... 270 41* Potassium K ..... ............... 271 42...923 209 NIckel-Palladium NI-Pd..................926 210 * Nickel-Pitaum Ni-Pt.................90 211 Nickel-Silicon NI-SI.................932 212

Nano-palladium is a cellular catalyst for in vivo chemistry

Science.gov (United States)

Miller, Miles A.; Askevold, Bjorn; Mikula, Hannes; Kohler, Rainer H.; Pirovich, David; Weissleder, Ralph

2017-07-01

Palladium catalysts have been widely adopted for organic synthesis and diverse industrial applications given their efficacy and safety, yet their biological in vivo use has been limited to date. Here we show that nanoencapsulated palladium is an effective means to target and treat disease through in vivo catalysis. Palladium nanoparticles (Pd-NPs) were created by screening different Pd compounds and then encapsulating bis[tri(2-furyl)phosphine]palladium(II) dichloride in a biocompatible poly(lactic-co-glycolic acid)-b-polyethyleneglycol platform. Using mouse models of cancer, the NPs efficiently accumulated in tumours, where the Pd-NP activated different model prodrugs. Longitudinal studies confirmed that prodrug activation by Pd-NP inhibits tumour growth, extends survival in tumour-bearing mice and mitigates toxicity compared to standard doxorubicin formulations. Thus, here we demonstrate safe and efficacious in vivo catalytic activity of a Pd compound in mammals.

Preparation of Palladium/Silver-Coated Polyimide Nanotubes: Flexible, Electrically Conductive Fibers

OpenAIRE

Lushi Kong; Guanchun Rui; Guangyu Wang; Rundong Huang; Ran Li; Jiajie Yu; Shengli Qi; Dezhen Wu

2017-01-01

A simple and practical method for coating palladium/silver nanoparticles on polyimide (PI) nanotubes is developed. The key steps involved in the process are silver ion exchange/reduction and displacement reactions between silver and palladium ions. With the addition of silver, the conductivity of the PI nanotubes is greatly enhanced. Further, the polyimide nanotubes with a dense, homogeneous coating of palladium nanoparticles remain flexible after heat treatment and show the possibility for u...

Palladium configuration dependence of hydrogen detection sensitivity based on graphene FET for breath analysis

Science.gov (United States)

Sakamoto, Yuri; Uemura, Kohei; Ikuta, Takashi; Maehashi, Kenzo

2018-04-01

We have succeeded in fabricating a hydrogen gas sensor based on palladium-modified graphene field-effect transistors (FETs). The negative-voltage shift in the transfer characteristics was observed with exposure to hydrogen gas, which was explained by the change in work function. The hydrogen concentration dependence of the voltage shift was investigated using graphene FETs with palladium deposited by three different evaporation processes. The results indicate that the hydrogen detection sensitivity of the palladium-modified graphene FETs is strongly dependent on the palladium configuration. Therefore, the palladium-modified graphene FET is a candidate for breath analysis.

Surface topography of a palladium cathode after electrolysis in heavy water

International Nuclear Information System (INIS)

Silver, D.S.; Dash, J.; Keefe, P.S.

1993-01-01

Electrolysis was performed with a palladium cathode and an electrolyte containing both hydrogen and deuterium ions. The cathode bends toward the anode during this process. Examination of both the concave and the convex surfaces with the scanning electron microscope, scanning tunneling microscope, and atomic force microscope shows unusual surface characteristics. Rimmed craters with faceted crystals inside and multitextural surfaces were observed on an electrolyzed palladium cathode but not on palladium that has not been electrolyzed. 9 refs., 9 figs

Toward Efficient Palladium-Catalyzed Allylic C-H Alkylation

DEFF Research Database (Denmark)

Jensen, Thomas; Fristrup, Peter

2009-01-01

Recent breakthroughs have proved that direct palladium (II)-catalyzed allylic C-H alkylation can be achieved. This new procedure shows that the inherent requirement for a leaving group in the Tsuji-Trost palladium-catalyzed allylic alkylation can be lifted. These initial reports hold great promise...... for the development of allylic C-H alkylation into a widely applicable methodology, thus providing a means to enhance synthetic efficiency in these reactions....

Palladium-Catalysed Coupling Reactions

NARCIS (Netherlands)

de Vries, Johannes G.; Beller, M; Blaser, HU

2012-01-01

Palladium-catalysed coupling reactions have gained importance as a tool for the production of pharmaceutical intermediates and to a lesser extent also for the production of agrochemicals, flavours and fragrances, and monomers for polymers. In this review only these cases are discussed where it seems

Synthesis and characterization of supported Pt and Pt alloys nanoparticles used for the catalytic oxidation of sulfur dioxide

DEFF Research Database (Denmark)

Koutsopoulos, Sotiris; Eriksen, Kim Michael; Fehrmann, Rasmus

2006-01-01

pressure in the temperature range of 250–700 °C. The effect of doping the active metal with rhodium and palladium was also studied. The catalytic activities of the supported catalysts were found to follow the order Pt–Pd/CPG > Pt–Rh/CPG > Pt/CPG. A significant synergistic effect of the Pt–Pd alloy...

High catalytic activity of ultrafine nanoporous palladium for electro-oxidation of methanol, ethanol, and formic acid

Energy Technology Data Exchange (ETDEWEB)

Wang, Xiaoguang; Wang, Weimin; Qi, Zhen; Zhao, Changchun; Ji, Hong; Zhang, Zhonghua [Key Laboratory for Liquid-Solid Structural Evolution and Processing of Materials (MOE), School of Materials Science and Engineering, Shandong University, Jingshi Road 73, Jinan 250061 (China)

2009-10-15

Nanoporous palladium (NPPd) with ultrafine ligament size of 3-6 nm was fabricated by dealloying of an Al-Pd alloy in an alkaline solution. Electrochemical measurements indicate that NPPd exhibits significantly high electrochemical active specific surface area (23 m{sup 2} g{sup -1}), and high catalytic activity for electro-oxidation of methanol, ethanol, and formic acid. Mass activities can reach 149, 148, 262 mA mg{sup -1} for the oxidation of methanol, ethanol and formic acid, respectively. Moreover, superior steady-state activities can be observed for all the electro-oxidation processes. NPPd will be a promising candidate for the anode catalyst for direct alcohol or formic acid fuel cells. (author)

Palladium-Catalyzed Atom-Transfer Radical Cyclization at Remote Unactivated C(sp3 )-H Sites: Hydrogen-Atom Transfer of Hybrid Vinyl Palladium Radical Intermediates.

Science.gov (United States)

Ratushnyy, Maxim; Parasram, Marvin; Wang, Yang; Gevorgyan, Vladimir

2018-03-01

A novel mild, visible-light-induced palladium-catalyzed hydrogen atom translocation/atom-transfer radical cyclization (HAT/ATRC) cascade has been developed. This protocol involves a 1,5-HAT process of previously unknown hybrid vinyl palladium radical intermediates, thus leading to iodomethyl carbo- and heterocyclic structures. © 2018 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

Thermodynamics of the hybrid interaction of hydrogen with palladium nanoparticles

NARCIS (Netherlands)

Griessen, R.P.; Strohfeldt, N.; Giessen, H.

2015-01-01

Palladium-hydrogen is a prototypical metal-hydrogen system. It is therefore not at all surprising that a lot of attention has been devoted to the absorption and desorption of hydrogen in nanosized palladium particles. Several seminal articles on the interaction of H with Pd nanocubes and

Degradation mode survey candidate titanium-base alloys for Yucca Mountain project waste package materials. Revision 1

Energy Technology Data Exchange (ETDEWEB)

Gdowski, G.E.

1997-12-01

The Yucca Mountain Site Characterization Project (YMP) is evaluating materials from which to fabricate high-level nuclear waste containers (hereafter called waste packages) for the potential repository at Yucca Mountain, Nevada. Because of their very good corrosion resistance in aqueous environments titanium alloys are considered for container materials. Consideration of titanium alloys is understandable since about one-third (in 1978) of all titanium produced is used in applications where corrosion resistance is of primary importance. Consequently, there is a considerable amount of data which demonstrates that titanium alloys, in general, but particularly the commercial purity and dilute {alpha} grades, are highly corrosion resistant. This report will discuss the corrosion characteristics of Ti Gr 2, 7, 12, and 16. The more highly alloyed titanium alloys which were developed by adding a small Pd content to higher strength Ti alloys in order to give them better corrosion resistance will not be considered in this report. These alloys are all two phase ({alpha} and {beta}) alloys. The palladium addition while making these alloys more corrosion resistant does not give them the corrosion resistance of the single phase {alpha} and near-{alpha} (Ti Gr 12) alloys.

Corrosion of titanium and titanium alloys in spent fuel repository conditions - literature review

International Nuclear Information System (INIS)

Aho-Mantila, I.; Haenninen, H.; Aaltonen, P.; Taehtinen, S.

1985-03-01

The spent nuclear fuel is planned to be disposed in Finnish bedrock. The canister of spent fuel in waste repository is one barrier to the release of radionuclides. It is possible to choose a canister material with a known, measurable corrosion rate and to make it with thickness allowing corrosion to occur. The other possibility is to use a material which is nearly immune to general corrosion. In this second category there are titanium and titanium alloys which exhibit a very high degree of resistance to general corrosion. In this literature study the corrosion properties of unalloyed titanium, titanium alloyed with palladium and titanium alloyed with molybdenum and nickel are reviewed. The two titanium alloys own in addition to the excellent general corrosion properties outstanding properties against localized corrosion like pitting or crevice corrosion. Stress corrosion cracking and corrosion fatique of titanium seem not to be a problem in the repository conditions, but the possibilities of delayed cracking caused by hydrogen should be carefully appreciated. (author)

A new combination of membranes and membrane reactors for improved tritium management in breeder blanket of fusion machines

International Nuclear Information System (INIS)

Demange, D.; Staemmler, S.; Kind, M.

2011-01-01

Tritium used as fuel in future fusion machines will be produced within the breeder blanket. The tritium extraction system recovers the tritium to be routed into the inner-fuel cycle of the machine. Accurate and precise tritium accountancy between both systems is mandatory to ensure a reliable operation. Handling in the blanket huge helium flow rates containing tritium as traces in molecular and oxide forms is challenging both for the process and the accountancy. Alternative tritium processes based on combinations of membranes and membrane reactors are proposed to facilitate the tritium management. The PERMCAT process is based on counter-current isotope swamping in a palladium membrane reactor. It allows recovering tritium efficiently from any chemical species. It produces a pure hydrogen stream enriched in tritium of advantage for integration upstream of the accountancy stage. A pre-separation and pre-concentration stage using new zeolite membranes has been studied to optimize the whole process. Such a combination could improve the tritium processes and facilitate accountancy in DEMO.

Ageing of palladium tritide: mechanical characterization, helium state and modelling

International Nuclear Information System (INIS)

Segard, M.

2010-01-01

Palladium is commonly used for the storage of tritium (the hydrogen radioactive isotope), since it forms a low-equilibrium-pressure and reversible tritide. Tritium decay into helium-3 is responsible for the ageing of the tritide, leading to the apparition of helium-3 bubbles for instance. Both experimental and theoretical aspects of this phenomenon are studied here.Previous works on ageing modelling led to two main models, dealing with:- Helium-3 bubbles nucleation (using a cellular automaton), - Bubbles growth (using continuum mechanics).These models were quite efficient, but their use was limited by the lack of input data and fitting experimental parameters.To get through these limitations, this work has consisted in studying the most relevant experimental data to improve the modelling of the palladium tritide ageing.The first part of this work was focused on the assessment of the mechanical properties of the palladium tritide (yield strength, ultimate strength, mechanical behaviour). They were deduced from the in situ tensile tests performed on palladium hydride and deuteride. In the second part, ageing characterization was undertaken, mainly focusing on: - Bubbles observations in palladium tritide using transmission electron microscopy, - Internal bubble pressure measurements using nuclear magnetic resonance, - Macroscopic swelling measurements using pycno-metry.The present work has led to significant progress in ageing understanding and has brought very valuable improvements to the modelling of such a phenomenon. (author) [fr

Palladium nanoparticle anchored polyphosphazene nanotubes ...

Indian Academy of Sciences (India)

607–610. c Indian Academy of Sciences. Palladium ... 2Department of Chemistry, APA College of Arts and Culture, Palani, Tamil Nadu 624 601, India. 3Department of .... K Dinakaran acknowledges the financial support from. Department of ...

Mechanism of the palladium-catalyzed hydrothiolation of alkynes to thioethers: a DFT study.

Science.gov (United States)

Zhang, Xing-hui; Geng, Zhi-yuan; Wang, Ke-tai; Li, Shan-shan

2014-09-01

The mechanisms of the palladium-catalyzed hydrothiolation of alkynes with thiols were investigated using density functional theory at the B3LYP/6-31G(d, p) (SDD for Pd) level. Solvent effects on these reactions were explored using the polarizable continuum model (PCM) for the solvent tetrahydrofuran (THF). Markovnikov-type vinyl sulfides or cis-configured anti-Markovnikov-type products were formed by three possible pathways. Our calculation results suggested the following: (1) the first step of the cycle is a proton-transfer process from thiols onto the palladium atom to form a palladium-thiolate intermediate. The palladium-thiolate species is attacked on alkynes to obtain an elimination product, liberating the catalyst. (2) The higher activation energies for the alkyne into the palladium-thiolate bond indicate that this step is the rate-determining step. The Markovnikov-type vinyl sulfide product is favored. However, for the aromatic alkyne, the cis-configured anti-Markovnikov-type product is favored. (3) The activation energy would reduce when thiols are substituted with an aromatic group. Our calculated results are consistent with the experimental observations of Frech and colleagues for the palladium-catalyzed hydrothiolation of alkynes to thiols.

Carbon nanotubes decorated with palladium nanoparticles : Synthesis, characterization, and catalytic activity

NARCIS (Netherlands)

Karousis, Nikolaos; Tsotsou, Georgia-Eleni; Evangelista, Fabrizio; Rudolf, Petra; Ragoussis, Nikitas; Tagmatarchis, Nikos

2008-01-01

In this article, the in situ preparation of palladium nanoparticles, as mediated by the self-regulated reduction of palladium acetate with the aid of sodium dodecyl sulfate (SDS), followed by subsequent deposition onto single-walled carbon nanotubes and multimalled carbon nanotubes (MWCNTs), is

Microwave-assisted synthesis of palladium nanocubes and nanobars

International Nuclear Information System (INIS)

Yu, Yanchun; Zhao, Yanxi; Huang, Tao; Liu, Hanfan

2010-01-01

Microwave was employed in the shape-controlled synthesis of palladium nanoparticles. Palladium nanocubes and nanobars with a mean size of about 23.8 nm were readily synthesized with H 2 PdCl 4 as a precursor, tetraethylene glycol (TEG) as both a solvent and a reducing agent in the presence of PVP and CTAB in 80 s under microwave irradiation. The structures of the as-prepared palladium nanoparticles were characterized by transmission electron microscopy (TEM), X-ray powder diffraction (XRD) and ultraviolet-visible (UV-vis) absorption spectroscopy. The formation of PdBr 4 2- due to the coordination replacement of the ligand Cl - ions in PdCl 4 2- ions by Br - ions in the presence of bromide was responsible for the synthesis of Pd nanocubes and nanobars. In addition, a milder reducing power, a higher viscosity and a stronger affinity of TEG were beneficial to the larger sizes of Pd nanocubes and nanobars.

Metallic Membranes for High Temperature Hydrogen Separation

DEFF Research Database (Denmark)

Ma, Y.H.; Catalano, Jacopo; Guazzone, Federico

2013-01-01

membrane fabrication methods have matured over the last decades, and the deposition of very thin films (1–5 µm) of Pd over porous ceramics or modified porous metal supports is quite common. The H2 permeances and the selectivities achieved at 400–500 °C were in the order of 50–100 Nm3/m/h/bar0.5 and greater......Composite palladium membranes have extensively been studied in laboratories and, more recently, in small pilot industrial applications for the high temperature separation of hydrogen from reactant mixtures such as water-gas shift (WGS) reaction or methane steam reforming (MSR). Composite Pd...... than 1000, respectively. This chapter describes in detail composite Pd-based membrane preparation methods, which consist of the grading of the support and the deposition of the dense metal layer, their performances, and their applications in catalytic membrane reactors (CMRs) at high temperatures (400...

Electronic influences in the diffusion of hydrogen in the alloy series of palladium

International Nuclear Information System (INIS)

Buchold, H.; Sicking, G.; Wicke, E.

1976-01-01

The mobility of tritium in Pd-alloys with Ag, V and Ni has been investigated by time-lag measurements, where the β-radiation of the tritium decay was taken as measuring signal; this method allows the determination of internal concentration shifts without disturbance by inhibiting effects of interface transfer. It has been found, that small additions of the alloying components do not change the activation energy of tritium diffusion; higher concentrations of Ag and V, however, lead to steep rises of the activation energy, whereas the isoelectronic Ni as alloying partner does not influence the activation energy within the limits of experimental error. For interpretation of the results the activation energy of diffusion is divided into a basic contribution of the Pd host lattice and an additional electronic term. This term is closely connected with the VEC, and can be calculated from the screening potential of the impurity atoms. The basic part of the activation energy can approximately be identified with the energy of elastic strain of the Pd lattice brought about by the diffusion jump. (orig.) [de

Growth and morphological analysis of segmented AuAg alloy nanowires created by pulsed electrodeposition in ion-track etched membranes

Directory of Open Access Journals (Sweden)

Ina Schubert

2015-06-01

Full Text Available Background: Multicomponent heterostructure nanowires and nanogaps are of great interest for applications in sensorics. Pulsed electrodeposition in ion-track etched polymer templates is a suitable method to synthesise segmented nanowires with segments consisting of two different types of materials. For a well-controlled synthesis process, detailed analysis of the deposition parameters and the size-distribution of the segmented wires is crucial.Results: The fabrication of electrodeposited AuAg alloy nanowires and segmented Au-rich/Ag-rich/Au-rich nanowires with controlled composition and segment length in ion-track etched polymer templates was developed. Detailed analysis by cyclic voltammetry in ion-track membranes, energy-dispersive X-ray spectroscopy and scanning electron microscopy was performed to determine the dependency between the chosen potential and the segment composition. Additionally, we have dissolved the middle Ag-rich segments in order to create small nanogaps with controlled gap sizes. Annealing of the created structures allows us to influence their morphology.Conclusion: AuAg alloy nanowires, segmented wires and nanogaps with controlled composition and size can be synthesised by electrodeposition in membranes, and are ideal model systems for investigation of surface plasmons.

Processing of Ni30Pt20Ti50 High-Temperature Shape-Memory Alloy Into Thin Rod Demonstrated

Science.gov (United States)

Noebe, Ronald D.; Draper, Susan L.; Biles, Tiffany A.; Leonhardt, Todd

2005-01-01

High-temperature shape-memory alloys (HTSMAs) based on nickel-titanium (NiTi) with significant ternary additions of palladium (Pd), platinum (Pt), gold (Au), or hafnium (Hf) have been identified as potential high-temperature actuator materials for use up to 500 C. These materials provide an enabling technology for the development of "smart structures" used to control the noise, emissions, or efficiency of gas turbine engines. The demand for these high-temperature versions of conventional shape-memory alloys also has been growing in the automotive, process control, and energy industries. However these materials, including the NiPtTi alloys being developed at the NASA Glenn Research Center, will never find widespread acceptance unless they can be readily processed into useable forms.

Oxygen Activated, Palladium Nanoparticle Catalyzed, Ultrafast Cross-Coupling of Organolithium Reagents

NARCIS (Netherlands)

Heijnen, Dorus; Tosi, Filippo; Vila, Carlos; Stuart, Marc C. A.; Elsinga, Philip H.; Szymanski, Wiktor; Feringa, Ben L.

2017-01-01

The discovery of an ultrafast cross-coupling of alkyland aryllithium reagents with a range of aryl bromides is presented. The essential role of molecular oxygen to form the active palladium catalyst was established; palladium nanoparticles that are highly active in cross-coupling reactions with

Palladium sulphide (PdS) films as a new thermoelectric sulphide compound

Energy Technology Data Exchange (ETDEWEB)

Ares, J.R.; Diaz-Chao, P.; Clamagirand, J.; Macia, M.D.; Ferrer, I.J.; Sanchez, C. [Universidad Autonoma de Madrid (Spain). Lab. de Materiales de Interes en Energias Renovables

2010-07-01

Palladium sulphide (PdS) films have been prepared by direct sulphuration of 20 nm thick palladium films at different temperatures (200 C < T < 450 C). Sulphurated films exhibit an unique crystalline phase: PdS. Seebeck coefficient and electrical resistivity of these films are between -110 and -150 {mu}V/K and {proportional_to} 0.08 to 0.8 {omega}cm depending on the sulphuration temperature. Negative sign of Seebeck coefficient indicates an n type conduction in all films. Discussion is focused on the influence of atomic ratio between sulphur and palladium as well as impurities arising from the substrate on transport properties. (orig.)

Method for recovering palladium and technetium values from nuclear fuel reprocessing waste solutions

Science.gov (United States)

Horwitz, E. Philip; Delphin, Walter H.

1979-07-24

A method for recovering palladium and technetium values from nuclear fuel reprocessing waste solutions containing these and other values by contacting the waste solution with an extractant of tricaprylmethylammonium nitrate in an inert hydrocarbon diluent which extracts the palladium and technetium values from the waste solution. The palladium and technetium values are recovered from the extractant and from any other coextracted values with a strong nitric acid strip solution.

Development of anodic stripping voltametry for the determination of palladium in high level nuclear waste

Energy Technology Data Exchange (ETDEWEB)

Bhardwaj, T. K. [North Carolina State University, Raleigh (United States); Sharma, H. S.; Affarwal, S. K. [Bhabha Atomic Research Centre, Mumbai (India); Jain, P. C. [Meerut College, Meerut (India)

2012-12-15

Deposition potential, deposition time, square wave frequency, rotation speed of the rotating disc electrode, and palladium concentration were studied on a Glassy Carbon Electrode (GCE) in 0.01M HCl for the determination of palladium in High Level Nuclear Waste (HLNW) by anodic stripping voltammetry. Experimental conditions were optimized for the determination of palladium at two different, 10-8 and 10-7 M, levels. Error and standard deviation of this method were under 1% for all palladium standard solutions. The developed technique was successfully applied as a subsidiary method for the determination of palladium in simulated high level nuclear waste with very good precision and high accuracy (under 1 % error and standard deviation).

Further studies on gold alloys used in fabrication of porcelain-fused-to-metal restorations.

Science.gov (United States)

Civjan, S; Huget, E F; Dvivedi, N; Cosner, H J

1975-03-01

Composition, microstructure, castability, mechanical properties, and heat treatment characteristics of two gold-palladium-silver-based alloys were studied. The materials exhibited compositional as well as microstructural differences. Clinically acceptable castings could not be obtained when manufacturers' recommended casting temperatures were used. Ultimate tensile strength, yield strength, modulus of elasticity, and Brinell hardness values for the alloys were comparable. The elastic limit of Cameo, however, was significantly higher than that of vivo-star. Maximum rehardening of annealed castings occurred on reheat treatment at temperatures between 1,200 and 1,300 F. As-cast specimens, however, were not heat hardenable. The sequence of heat treatments used in the application of porcelain reduced slightly the hardness of both alloys. Hardness of the metal substructures was not increased by return of porcelain-coated specimens to a 1,250 F oven for final heat treatment.

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).

Palladium silicide - a new contact for semiconductor radiation detectors

International Nuclear Information System (INIS)

Totterdell, D.H.J.

1981-11-01

Silicide layers can be used as low resistance contacts in semiconductor devices. The formation of a metal rich palladium silicide Pd 2 Si is discussed. A palladium film 100A thick is deposited at 300 0 C and the resulting silicide layer used as an ohmic contact in an n + p silicon detector. This rugged contact has electrical characteristics comparable with existing evaporated gold contacts and enables the use of more reproducible bonding techniques. (author)

Metal allergen of the 21st century--a review on exposure, epidemiology and clinical manifestations of palladium allergy

DEFF Research Database (Denmark)

Faurschou, Annesofie; Menné, Torkil; Johansen, Jeanne D

2011-01-01

Consumers are mainly exposed to palladium from jewellery and dental restorations. Palladium contact allergy is nearly always seen together with nickel allergy, as palladium and nickel tend to cross-react. We aimed to analyse the available palladium patch test data and case reports to determine...

Study of the bipolar electrolysis of the tritiated water applied to the hydrogen isotopes separation by electrochemical permeation threw Pd-Ag alloy membranes

International Nuclear Information System (INIS)

Heinze, S.

2000-01-01

The objective of the study is to enrich waters of poor tritium concentration, by electrolysis in the same time of an hydrogen emission of low activity. In this framework the hydrogen electrochemical permeation threw Pd-Ag alloy membranes has been used. The first part of the study concerns the hydrogen and the deuterium diffusion threw these membranes. The activation and the thermal treatments influence have been studied. A relation between the membrane microstructure and the diffusion mechanism has been proposed. The second part of the study is devoted to the hydrogen gate mechanism determination in the membrane by impedance spectroscopy. The last part concerns the determination of the isotopic separation factor hydrogen-deuterium. Experimental results agree the calculated theoretical data. The operation of an operational membrane cell has been simulated and the process feasibility has been proved. (A.L.B.)

Thin film platinum–palladium thermocouples for gas turbine engine applications

Energy Technology Data Exchange (ETDEWEB)

Tougas, Ian M.; Gregory, Otto J., E-mail: gregory@egr.uri.edu

2013-07-31

Thin film platinum:palladium thermocouples were fabricated on alumina and mullite surfaces using radio frequency sputtering and characterized after high temperature exposure to oxidizing environments. The thermoelectric output, hysteresis, and drift of these sensors were measured at temperatures up to 1100 °C. Auger electron spectroscopy was used to follow the extent of oxidation in each thermocouple leg and interdiffusion at the metallurgical junction. Minimal oxidation of the platinum and palladium thermoelements was observed after high temperature exposure, but considerable dewetting and faceting of the films were observed in scanning electron microscopy. An Arrhenius temperature dependence on the drift rate was observed and later attributed to microstructural changes during thermal cycling. The thin film thermocouples, however, did exhibit excellent stability at 1000 °C with drift rates comparable to commercial type-K wire thermocouples. Based on these results, platinum:palladium thin film thermocouples have considerable potential for use in the hot sections of gas turbine engines. - Highlights: • Stable thin film platinum:palladium thermocouples for gas turbine engines • Little oxidation but significant microstructural changes from thermal cycling • Minimal hysteresis during repeated thermal cycling • Drift comparable to commercial wire thermocouples.

Oxygen isotope exchange on palladium catalysts

International Nuclear Information System (INIS)

Kravchuk, L.S.; Beschetvertnaya, T.I.; Novorodskij, V.G.; Novikova, M.G.; Zaretskij, M.V.; Valieva, S.V.

1983-01-01

Oxygen heteromolecular isotope exchange on unreduced palladium catalysts, distingushing by metal content is studied. Content of 18 O in gaseous phase is eoual to 46%. Calculations of heteroexchange rates are conducted with decrease of the 18 O in the gaseous phase over solid sample. Method of oxygen thermodesorption has been used to establish that palladium, deposited on γ-Al 2 O 3 during exchange process is in oxidized state; in this case strength of Pd-O bond is determined by content dispersity) of the metal. It is shown that significant increase of exchange rate on the samples with Pd >> 0.5 mass.% content can be induced as by side decomposition reaction of its oxide and corresponding dilution of gaseous mixture by ''light'' oxygen so by possibility of exchange with oxygen of PdO phase

TA [B] Predicting Microstructure-Creep Resistance Correlation in High Temperature Alloys over Multiple Time Scales

Energy Technology Data Exchange (ETDEWEB)

Tomar, Vikas [Purdue Univ., West Lafayette, IN (United States)

2017-03-06

DoE-NETL partnered with Purdue University to predict the creep and associated microstructure evolution of tungsten-based refractory alloys. Researchers use grain boundary (GB) diagrams, a new concept, to establish time-dependent creep resistance and associated microstructure evolution of grain boundaries/intergranular films GB/IGF controlled creep as a function of load, environment, and temperature. The goal was to conduct a systematic study that includes the development of a theoretical framework, multiscale modeling, and experimental validation using W-based body-centered-cubic alloys, doped/alloyed with one or two of the following elements: nickel, palladium, cobalt, iron, and copper—typical refractory alloys. Prior work has already established and validated a basic theory for W-based binary and ternary alloys; the study conducted under this project extended this proven work. Based on interface diagrams phase field models were developed to predict long term microstructural evolution. In order to validate the models nanoindentation creep data was used to elucidate the role played by the interface properties in predicting long term creep strength and microstructure evolution.

Polarographic determination of selenium and tellurium in silver-gold alloys

International Nuclear Information System (INIS)

Gornostaeva, T.D.; Shmargun, S.V.

1986-01-01

The determination of selenium and tellurium is of importance in monitoring the composition of silver-gold alloys (SGA) since these elements are harmful impurities in the pure metals. Tellurium is determined in silver alloys by atomic absorption and atomic emmission methods; selenium determination is made by atomic absorption methods. This paper examines the polarographic determination of silver and tellurium in SGA containing platinum metals and copper. Copper and the bulk of the platinum and palladium were removed by precipitating selenium and tellurium with potassium hypophosphite in the elementary state from 6 M HC1. The results of an analysis of samples of SGA according to the proposed method were compared with the results obtained by the atomic absorption method. the relative deviation in the determination of 0.02-1.0% by weight selenium and tellurium does not exceed 0.12 (n = 5)

Recovery of nonradioactive palladium and rhodium from high-level radioactive wastes

International Nuclear Information System (INIS)

McDuffie, H.F.

1979-01-01

A possible method for recovering significant quantities of nonradioactive palladium from fission-product wastes requires essentially complete separation of the fission-product (radioactive) palladium from fission-product ruthenium. After the decay of 106 Ru via 106 Rh to 106 Pd, this nonradioactive palladium is recovered for normal commercial use. The U.S. production of palladium has never been above 1000 kg per year vs consumption of about 46,000 kg per year. Most of the supply comes from Russia and South Africa. It has been estimated that a 400-GW(e) nuclear reactor economy will make available 2000 kg per year of 106 Ru at reactor fuel discharge. A substantial increase might be achieved if plutonium were recycled as fissionable material because of the higher yields of the 106 chain from plutonium. A literature search has uncovered support for three promising approaches to the required separation of palladium from ruthenium: (1) recrystallization from solution in bismuth or in zinc; (2) selective precipitation of a titanium--ruthenium intermetallic compound from bismuth, followed by precipitation of a zinc--palladium intermetallic compound; and (3) dissolution in molten magnesium followed by partitioning between molten magnesium and a molten uranium-5 wt % chromium eutectic at a temperature above 870 0 C. Liquid-liquid extraction appears to be the most promising method from a technological point of view, although intermetallic compound formation is much more interesting chemically. Recovery of some nonradioactive 103 Rh may be possible by liquid-liquid extraction of the fuel before the decay of the 39.8-d 103 Ru has gone substantially to completion. Demonstration of the practicality of these separations will contribute a positive factor to the evaluation of resumption in the United States of nuclear fuel reprocessing and plutonium recycle in light-water-moderated reactors

In situ synthesis of carbon nanotubes decorated with palladium nanoparticles using arc-discharge in solution method

International Nuclear Information System (INIS)

Bera, Debasis; Kuiry, Suresh C.; McCutchen, Matthew; Seal, Sudipta; Heinrich, Helge; Slane, Grady C.

2004-01-01

A unique, simple, inexpensive, and one-step synthesis route to produce carbon nanotubes (CNTs) decorated with palladium nanoparticles using a simplified dc arc-discharge in solution is reported. Zero-loss energy filtered transmission electron microscopy and scanning transmission electron microscopy confirm the presence of 3 nm palladium nanoparticles. Such palladium nanoparticles form during the reduction of palladium tetra-chloro-square-planar complex. The deconvoluted x-ray photoelectron spectroscopy envelope shows the presence of palladium on the decorated CNTs. The energy dispersive spectroscopy suggests no functionalization of atomic chlorine to the sidewall of the CNTs. The presence of dislodged graphene sheets with wavy morphology supports the formation of CNTs through the 'scroll mechanism'

Electrochemical behavior of fission palladium in 1-butyl-3-methylimidazolium chloride

Energy Technology Data Exchange (ETDEWEB)

Jayakumar, M.; Venkatesan, K.A.; Srinivasan, T.G. [Fuel Chemistry Division, Indira Gandhi Centre for Atomic Research, Kalpakkam 603102 (India)

2007-08-01

Electrochemical behavior of palladium (II) chloride in 1-butyl-3-methylimidazolium chloride has been investigated by various electrochemical transient techniques using glassy carbon working electrode at different temperatures (343-373 K). Cyclic voltammogram consisted of a prominent reduction wave at -0.61 V (vs. Pd) due to the reduction of Pd(II) to Pd, and two oxidation waves at -0.26 and 0.31 V. A nucleation loop is observed at -0.53 V. The diffusion coefficient of palladium (II) in bmimCl ({proportional_to}10{sup -7} cm{sup 2}/s) was determined and the energy of activation (63 kJ/mol) was deduced from the cyclic voltammograms at various temperatures. Nucleation and growth of palladium on glassy carbon working electrode has been investigated by chronoamperometry and chronopotentiometry. The growth and decay of chronocurrents measured for palladium deposition has been found to follow the instantaneous nucleation model with three-dimensional growth of nuclei. The surface morphology of the deposit obtained at various applied potentials revealed the formation of dendrites immediately after nucleation and spread in all the directions with time. (author)

Preparation of Palladium/Silver-Coated Polyimide Nanotubes: Flexible, Electrically Conductive Fibers.

Science.gov (United States)

Kong, Lushi; Rui, Guanchun; Wang, Guangyu; Huang, Rundong; Li, Ran; Yu, Jiajie; Qi, Shengli; Wu, Dezhen

2017-11-02

A simple and practical method for coating palladium/silver nanoparticles on polyimide (PI) nanotubes is developed. The key steps involved in the process are silver ion exchange/reduction and displacement reactions between silver and palladium ions. With the addition of silver, the conductivity of the PI nanotubes is greatly enhanced. Further, the polyimide nanotubes with a dense, homogeneous coating of palladium nanoparticles remain flexible after heat treatment and show the possibility for use as highly efficient catalysts. The approach developed here is applicable for coating various noble metals on a wide range of polymer matrices, and can be used for obtaining polyimide nanotubes with metal loaded on both the inner and outer surface.

Preparation of Palladium/Silver-Coated Polyimide Nanotubes: Flexible, Electrically Conductive Fibers

Directory of Open Access Journals (Sweden)

Lushi Kong

2017-11-01

Full Text Available A simple and practical method for coating palladium/silver nanoparticles on polyimide (PI nanotubes is developed. The key steps involved in the process are silver ion exchange/reduction and displacement reactions between silver and palladium ions. With the addition of silver, the conductivity of the PI nanotubes is greatly enhanced. Further, the polyimide nanotubes with a dense, homogeneous coating of palladium nanoparticles remain flexible after heat treatment and show the possibility for use as highly efficient catalysts. The approach developed here is applicable for coating various noble metals on a wide range of polymer matrices, and can be used for obtaining polyimide nanotubes with metal loaded on both the inner and outer surface.

Radiochemical neutron activation analysis of high pure palladium and platinum by ion exchange chromatography

International Nuclear Information System (INIS)

Sadikov, I.I.; Zinov'ev, V.G.; Sadikova, Z.O.; Salimov, M.I.

2006-01-01

Full text: The palladium and platinum are widely used for jewel manufacture because of their beautiful white color. However the most part of these metals are widely adopted in the world as catalysts. Many works on analytical chemistry of platinum group elements published during last years are devoted to determination of platinum and palladium in other materials. There are no articles on analysis technique of the palladium and platinum purity published during last 20 years. Available publications are very old and are published till 70th of the last century, and implement chemical and spectral methods. At the same time, the palladium and platinum are very suitable for NAA. Therefore the purpose of our research was development of high-sensitivity and multielement techniques of radiochemical neutron activation analysis of a high pure palladium and platinum. Research of nuclear characteristics of palladium and platinum has shown that radioactive nuclides with different yields are formed under the reactor neutrons. 109 , 111 , 111m Pd, 109m , 111 Ag, 191 , 197 , 199 Pt, 199 Au are the most important among them. 109Pd separation factor is equal to 1*10 5 at palladium analysis, whereas 197 Pt and 199 Au separation factor is equal to 1*10 4 at the platinum analysis every other day after irradiation. Palladium and platinum can be separated by precipitation, extraction and ion exchange methods. For separation of radioactive nuclide of the matrix elements from the impurity elements we used ion exchange chromatography system Dowex-1x8 - 1 M HNO 3 for palladium and Dowex-1x8 - 0.1 M HNO 3 for platinum. At the HNO 3 acid concentrations variation from 0,1 M to 1 M more then 25 elements have distribution factors less than 1 and 10 elements have distribution factors 5 while matrix elements have distribution factors higher than 100. It allows an effective separation of these elements from palladium and platinum. Optimum sizes of the chromatographic column and the column effluent

Factors affecting the corrosion of SiC layer by fission product palladium

International Nuclear Information System (INIS)

Dewita, E.

2000-01-01

HTR is one of the advanced nuclear reactors which has inherent safety system, graphite moderated and helium gas cooled. In general, these reactors are designed with the TRISO coated particle consist of four coating layers that are porous pyrolytic carbon (PyC). inner dense PyC (IPyC), silicon carbide (SiC), and outer dense PyC (OPyC). Among the four coating layers, the SiC plays an important role beside in retaining metallic fission products, it also provides mechanical strength to fuel particle. However, results of post irradiation examination indicate that fission product palladium can react with and corrode SiC layer, This assessment is conducted to get the comprehension about resistance of SiC layer on irradiation effects, especially in order to increase the fuel bum-up. The result of this shows that the corrosion of SiC layer by fission product palladium is beside depend on the material characteristics of SiC, and also there are other factors that affect on the SiC layer corrosion. Fuel enrichment, bum-up, and irradiation time effect on the palladium flux in fuel kernel. While, the fuel density, vapour pressure of palladium (the degree depend on the irradiation temperature and kernel composition) effect on palladium migration in fuel particle. (author)

Membrane reforming in converting natural gas to hydrogen: Production costs, Part II

Energy Technology Data Exchange (ETDEWEB)

Iaquaniello, G; Cosenza, S [Technip-KTI S.p.A., via Castello della Magliana 75, Rome (Italy); Giacobbe, F; Morico, B; Farace, A [Processi Innovativi s.r.l., L' Aquila (Italy)

2008-11-15

This paper evaluates the production costs of a hybrid system based on a new membrane reforming MRR concept to convert natural gas to hydrogen and electricity. Membrane reforming with hydrogen-selective, palladium-silver membranes pushes the chemical equilibrium and allows higher methane conversions at lower temperature such as 650 C. The new MRR concept formed of a series of modules is put forward herein. Each module is made up of a reforming step and an external membrane separation unit. The estimates, based on utilities costs of a typical Italian refinery (end of 2006), show that the production costs for the hybrid system are 30% less than conventional tubular steam reforming technology, and 13% less than a gas-fired cogeneration plant coupled with a conventional H{sub 2} plant. (author)

The electrocatalytical reduction of m-nitrophenol on palladium nanoparticles modified glassy carbon electrodes

International Nuclear Information System (INIS)

Shi Qiaofang; Diao Guowang

2011-01-01

Highlights: ► The deposition of palladium on a GC electrode was performed by cyclic voltammetry. ► SEM images showed palladium nanoparticles deposited on a glassy carbon (GC) electrode. ► The Pd/GC electrode can effectively catalyze m-nitrophenol in aqueous media. ► The reduction of m-nitrophenol on the Pd/GC electrode depended on potential and pH. ► XPS spectra of the Pd/GC electrodes demonstrated the presence of palladium. - Abstract: Palladium nanoparticles modified glassy carbon electrodes (Pd/GC) were prepared via the electrodeposition of palladium on a glassy carbon (GC) electrode using cyclic voltammetry in different sweeping potential ranges. The scanning electron microscope images of palladium particles on the GC electrodes indicate that palladium particles with diameters of 20–50 nm were homogeneously dispersed on the GC electrode at the optimal deposition conditions, which can effectively catalyze the reduction of m-nitrophenol in aqueous solutions, but their catalytic activities are strongly related to the deposition conditions of Pd. The X-ray photoelectron spectroscopy spectra of the Pd/GC electrode confirmed that 37.1% Pd was contained in the surface composition of the Pd/GC electrode. The cyclic voltammograms of the Pd/GC electrode in the solution of m-nitrophenol show that the reduction peak of m-nitrophenol shifts towards the more positive potentials, accompanied with an increase in the peak current compared to the bare GC electrode. The electrocatalytic activity of the Pd/GC electrode is affected by pH values of the solution. In addition, the electrolysis of m-nitrophenol under a constant potential indicates that the reduction current of m-nitrophenol on the Pd/GC electrode is approximately 20 times larger than that on the bare GC electrode.

Palladium(II)-Stabilized Pyridine-2-Diazotates: Synthesis, Structural Characterization, and Cytotoxicity Studies.

Science.gov (United States)

Tskhovrebov, Alexander G; Vasileva, Anna A; Goddard, Richard; Riedel, Tina; Dyson, Paul J; Mikhaylov, Vladimir N; Serebryanskaya, Tatiyana V; Sorokoumov, Viktor N; Haukka, Matti

2018-02-05

Well-defined diazotates are scarce. Here we report the synthesis of unprecedented homoleptic palladium(II) diazotate complexes. The palladium(II)-mediated nitrosylation of 2-aminopyridines with NaNO 2 results in the formation of metal-stabilized diazotates, which were found to be cytotoxic to human ovarian cancer cells.

Interaction between Palladium Nanoparticles and Surface-Modified Carbon Nanotubes: Role of Surface Functionalities

DEFF Research Database (Denmark)

Zhang, Bingsen; Shao, Lidong; Zhang, Wei

2014-01-01

degrees C. We focus on probing the effects of oxygen and nitrogen-containing functional groups on supported palladium nanoparticles (NPs) in the model catalytic system. The stability of palladium NPs supported on CNTs depends strongly on the surface properties of CNTs. Moreover, the oxygen...... feature, instability, and subtle response of the components upon application of an external field. Herein, we use insitu TEM, electron energy loss spectroscopy, and X-ray photoelectron spectroscopy techniques to record the interaction in palladium on carbon nanotubes (CNTs) from room temperature to 600...

Carbonylation of 1-hexene in the presence of palladium-anion-exchange resin catalysts

Energy Technology Data Exchange (ETDEWEB)

Lapidus, A.L.; Pirozhkov, S.D.; Buiya, M.A.; Lunin, A.F.; Karapetyan, L.P.; Saldadze, K.M.

1986-06-20

Activated charcoal, silica gel, and zeolites containing palladium are active in the carbonylation of lower olefins by carbon monoxide. In the present work, they studied the carbonylation of 1-hexene in the presence of a series of palladium catalysts containing An-221, An-251, and AN-511 anion-exchange catalysts produced in the USSR as the supports. A catalyst obtained by the deposition of palladium(II) on weakly basic anion-exchange resins displays high efficiency in the carbonylation of 1-hexene with the formation of a nixture of enanthoic and 2-methylcaproic acids.

New Palladium-Catalyzed Approaches to Heterocycles and Carbocycles

Energy Technology Data Exchange (ETDEWEB)

Huang, Qinhua [Iowa State Univ., Ames, IA (United States)

2004-12-19

The tert-butylimines of o-(1-alkynyl)benzaldehydes and analogous pyridinecarbaldehydes have been cyclized under very mild reaction conditions in the presence of I₂, ICl, PhSeCl, PhSCl and p-O₂NC₆H₄SCl to give the corresponding halogen-, selenium- and sulfur-containing disubstituted isoquinolines and naphthyridines, respectively. Monosubstituted isoquinolines and naphthyridines have been synthesized by the metal-catalyzed ring closure of these same iminoalkynes. This methodology accommodates a variety of iminoalkynes and affords the anticipated heterocycles in moderate to excellent yields. The Pd(II)-catalyzed cyclization of 2-(1-alkynyl)arylaldimines in the presence of various alkenes provides an efficient way to synthesize a variety of 4-(1-alkenyl)-3-arylisoquinolines in moderate to excellent yields. The introduction of an ortho-methoxy group on the arylaldimine promotes the Pd-catalyzed cyclization and stabilizes the resulting Pd(II) intermediate, improving the yields of the isoquinoline products. Highly substituted naphthalenes have been synthesized by the palladium-catalyzed annulation of a variety of internal alkynes, in which two new carbon-carbon bonds are formed in a single step under relatively mild reaction conditions. This method has also been used to synthesize carbazoles, although a higher reaction temperature is necessary. The process involves arylpalladation of the alkyne, followed by intramolecular Heck olefination and double bond isomerization. This method accommodates a variety of functional groups and affords the anticipated highly substituted naphthalenes and carbazoles in good to excellent yields. Novel palladium migratiodarylation methodology for the synthesis of complex fused polycycles has been developed, in which one or more sequential Pd-catalyzed intramolecular migration processes involving C-H activation are employed. The chemistry works best with electron-rich aromatics, which is in agreement

Nanostructured palladium tailored via carbonyl chemical route towards oxygen reduction reaction

International Nuclear Information System (INIS)

Luo, Y.; Mora-Hernández, J.M.; Estudillo-Wong, L.A.; Arce-Estrada, E.M.; Alonso-Vante, N.

2015-01-01

Graphical Abstract: Mass-depending morphologies of nanostructured Palladium obtained via the carbonyl chemical route. Display Omitted -- Highlights: •Mass-depending morphology was observed in nanostructured palladium supported on carbon prepared by the carbonyl chemical route. •The Morphological effect of carbon supported Pd was investigated towards ORR. -- Abstract: Carbon supported palladium nanostructures were synthesized via the carbonyl chemical route. Compared with nanostructured platinum, prepared via carbonyl chemical route, Pd nanomaterials showed mass-loading morphology, whereas particle size and morphology of Pt nanostructures was constant. The oxygen reduction reaction (ORR) on nanostructured Pd, with different morphology in both acid and alkaline medium was investigated. A relationship, based on X-ray diffraction structural analysis pattern, transmission electron microscope, with the Pd morphological effect on ORR activity was identified

Shaping surface of palladium nanospheres through the control of reaction parameters

International Nuclear Information System (INIS)

Wang Lianmeng; Tan Enzhong; Guo Lin; Wang Lihua; Han Xiaodong

2011-01-01

Solid, cracked, and flower-shaped surfaces of palladium nanospheres with high yields and good uniformity were successfully prepared by a wet chemical method. On the basis of the experimental data, the same size of palladium nanosphere with different surface morphologies can be regulated only by changing the amount of ammonium hydroxide and reductant in one experimental system. The as-prepared products were studied by transmission electron microscopy (TEM), scanning electron microscopy (SEM) and x-ray diffraction (XRD). In addition, surface-enhanced Raman scattering (SERS) spectra on the as-prepared different surface of palladium nanospheres exhibit high activity towards p-aminothiophenol (PATP) detection, and the result further reveals that the predominance of the a1 vibration mode in the SERS spectra via an electromagnetic (EM) mechanism is significant.

Permeability of hydrogen isotopes through Pd-Ag membrane

International Nuclear Information System (INIS)

Yoshida, Hiroshi

1981-01-01

This paper represents the permeabilities, diffusion coefficients and isotope effects for hydrogen and deuterium through Pd-25 wt.% Ag alloy tubes The feed gas H 2 or D 2 flowing into the permeation cell was preheated before it reached to the outer surface of the permeation tube made of palladium-silver alloy. Permeation time lag method could be successfully carried out with the present apparatus to measure both permeability and diffusion coefficient. The square-root pressure dependence for the permeation of hydrogen isotopes was observed. The observed systematic temperature dependence indicates that the approximation of the Arrhenius' relation was effective within this experimental conditions. Some tendency of permeation fluxes in relation to the reciprocal temperature, 1/T, was seen. The permeability ratio was larger than the square root of isotopic mass ratio, and it decreased with temperature rise. On the contrary, the diffusion coefficient ratio was much smaller than the square root of isotopic mass ratio. (Kato, T.)

Substoichiometric extraction of traces of gold and palladium

International Nuclear Information System (INIS)

Colonat, J.-F.

1975-01-01

Several systems for extracting palladium at concentrations ranging from 10 -4 to 10 -6 M/l were studied. Extraction by dithizone is limited by the transformation of the primary complex into a secondary complex which takes place at concentrations around 10 -6 M. This transformation has been demonstrated kinetically. Dimethylglyoxime is an interesting reagent in substoichiometry, in spite of its comparatively low extraction constant. Various complexes which are formed in a highly chlorinated medium have been proposed. Use of copper diethyldithiocarbamate is limited principally by its stability in presence of chlorine ions. The kinetic formation of palladium diethyldithiocarbamate has been studied with greater precision. A direct determination of 100μg of palladium in a copper matrix without preliminary separation has given results comparable in every way with those of other methods. In the case of gold (III) the constants of formation with the diethyldithiocarbamate ion have been determined by an iterative method of calculation, using the influence curves of interfering metals. Finally conditions for an automatization of the substoichiometric extraction, as well as its possibilities for gold determination in the range 200-20ppm, were proposed [fr

Determination of palladium in various samples by atomic absorption spectrometry after preconcentration with dimethylglyoxime on silica gel

International Nuclear Information System (INIS)

Tokalioglu, Serife; Oymak, Tuelay; Kartal, Senol

2004-01-01

A preconcentration method based on the adsorption of palladium-dimethylglyoxime (DMG) complex on silica gel for the determination of palladium at trace levels by atomic absorption spectrometry (AAS) has been developed. The retained palladium as Pd(DMG) 2 complex was eluted with 1 mol l -1 HCl in acetone. The effect of some analytical parameters such as pH, amount of reagent and the sample volume on the recovery of palladium was examined in synthetic solutions containing street dust matrix. The influence of some matrix ions on the recovery of palladium was investigated by using the developed method when the elements were present both individually and together. The results showed that 2500 μg ml -1 Na + , K + , Mg 2+ , Al 3+ and Fe 3+ ; 5000 μg ml -1 Ca 2+ ; 500 μg ml -1 Pb 2+ ; 125 μg ml -1 Zn 2+ ; 50 μg ml -1 Cu 2+ and 25 μg ml -1 Ni 2+ did not interfere with the palladium signal. At the optimum conditions determined experimentally, the recovery for palladium was found to be 95.3±1.2% at the 95% confidence level. The relative standard deviation and limit of detection (3s/b) of the method were found to be 1.7% and 1.2 μg l -1 , respectively. In order to determine the adsorption behaviour of silica gel, the adsorption isotherm of palladium was studied and the binding equilibrium constant and adsorption capacity were calculated to be 0.38 l mg -1 and 4.06 mg g -1 , respectively. The determination of palladium in various samples was performed by using both flame AAS and graphite furnace AAS. The proposed method was successfully applied for the determination of palladium in the street dust, anode slime, rock and catalytic converter samples

Nickel, palladium and rhodium induced IFN-gamma and IL-10 production as assessed by in vitro ELISpot-analysis in contact dermatitis patients

Science.gov (United States)

Bordignon, Valentina; Palamara, Francesca; Cordiali-Fei, Paola; Vento, Antonella; Aiello, Arianna; Picardo, Mauro; Ensoli, Fabrizio; Cristaudo, Antonio

2008-01-01

Background Recent attempts to diminish nickel use in most industrial products have led to an increasing utilization of alternative metal compounds for destinations such as the alloys used in orthopaedics, jewellery and dentistry. The present study was undertaken with the aim to evaluate the potential for an allergic response to nickel, palladium and rhodium on the basis of antigen-specific induction of inflammatory/regulatory cytokines, and to characterize, according to the cytokine profiles, the nature of simultaneous positive patch tests elicited in vivo. Peripheral blood mononuclear cells (PBMC) from 40 patients with different patch test results were kept in short term cultures in the presence of optimized concentrations of NiSO4 × 6H2O, PdCl2 and Rh(CH3COO)2. The production of IFN-γ and IL-10 elicited by metal compounds were analyzed by the ELISpot assay. Results We found a specific IFN-γ response by PBMC upon in vitro stimulation with nickel or palladium in well recognized allergic individuals. All controls with a negative patch test to a metal salt showed an in vitro IL-10 response and not IFN-γ production when challenged with the same compound. Interestingly, all subjects with positive patch test to both nickel and palladium (group 3) showed an in vitro response characterized by the release of IFN-γ after nickel stimulation and production of IL-10 in response to palladium. Conclusion These results strongly suggest that the different cytokine profiles elicited in vitro reflect different immune responses which may lead to the control of the allergic responses or to symptomatic allergic contact dermatitis. The development of sensitive and specific in vitro assays based on the determination of the cytokine profiles in response to contact allergens may have important diagnostic and prognostic implications and may prove extremely useful in complementing the diagnostic limits of traditional patch testing. PMID:18482439

Nickel, palladium and rhodium induced IFN-gamma and IL-10 production as assessed by in vitro ELISpot-analysis in contact dermatitis patients

Directory of Open Access Journals (Sweden)

Ensoli Fabrizio

2008-05-01

Full Text Available Abstract Background Recent attempts to diminish nickel use in most industrial products have led to an increasing utilization of alternative metal compounds for destinations such as the alloys used in orthopaedics, jewellery and dentistry. The present study was undertaken with the aim to evaluate the potential for an allergic response to nickel, palladium and rhodium on the basis of antigen-specific induction of inflammatory/regulatory cytokines, and to characterize, according to the cytokine profiles, the nature of simultaneous positive patch tests elicited in vivo. Peripheral blood mononuclear cells (PBMC from 40 patients with different patch test results were kept in short term cultures in the presence of optimized concentrations of NiSO4 × 6H2O, PdCl2 and Rh(CH3COO2. The production of IFN-γ and IL-10 elicited by metal compounds were analyzed by the ELISpot assay. Results We found a specific IFN-γ response by PBMC upon in vitro stimulation with nickel or palladium in well recognized allergic individuals. All controls with a negative patch test to a metal salt showed an in vitro IL-10 response and not IFN-γ production when challenged with the same compound. Interestingly, all subjects with positive patch test to both nickel and palladium (group 3 showed an in vitro response characterized by the release of IFN-γ after nickel stimulation and production of IL-10 in response to palladium. Conclusion These results strongly suggest that the different cytokine profiles elicited in vitro reflect different immune responses which may lead to the control of the allergic responses or to symptomatic allergic contact dermatitis. The development of sensitive and specific in vitro assays based on the determination of the cytokine profiles in response to contact allergens may have important diagnostic and prognostic implications and may prove extremely useful in complementing the diagnostic limits of traditional patch testing.

Preparation of Palladium-Impregnated Ceria by Metal Complex Decomposition for Methane Steam Reforming Catalysis

Directory of Open Access Journals (Sweden)

Worawat Wattanathana

2017-01-01

Full Text Available Palladium-impregnated ceria materials were successfully prepared via an integrated procedure between a metal complex decomposition method and a microwave-assisted wetness impregnation. Firstly, ceria (CeO2 powders were synthesized by thermal decomposition of cerium(III complexes prepared by using cerium(III nitrate or cerium(III chloride as a metal source to form a metal complex precursor with triethanolamine or benzoxazine dimer as an organic ligand. Palladium(II nitrate was consequently introduced to the preformed ceria materials using wetness impregnation while applying microwave irradiation to assist dispersion of the dopant. The palladium-impregnated ceria materials were obtained by calcination under reduced atmosphere of 10% H2 in He stream at 700°C for 2 h. Characterization of the palladium-impregnated ceria materials reveals the influences of the metal complex precursors on the properties of the obtained materials. Interestingly, the palladium-impregnated ceria prepared from the cerium(III-benzoxazine dimer complex revealed significantly higher BET specific surface area and higher content of the more active Pdδ+ (δ > 2 species than the materials prepared from cerium(III-triethanolamine complexes. Consequently, it exhibited the most efficient catalytic activity in the methane steam reforming reaction. By optimization of the metal complex precursors, characteristics of the obtained palladium-impregnated ceria catalysts can be modified and hence influence the catalytic activity.

Palladium emissions in the environment: analytical methods, environmental assessment and health effects

National Research Council Canada - National Science Library

Alt, Friedrich; Zereini, Fathi

2006-01-01

... (Eds)). But there is a clear lack of information concerning palladium. It is very important to condense the present state of research findings from emission to potential health risks for the environment and humans. Very important is the chapter about analytical determination of palladium, which shows clearly the problems of several analytic...

The study of hydrogen electrosorption in layered nickel foam/palladium/carbon nanofibers composite electrodes

International Nuclear Information System (INIS)

Skowronski, J.M.; Czerwinski, A.; Rozmanowski, T.; Rogulski, Z.; Krawczyk, P.

2007-01-01

In the present work, the process of hydrogen electrosorption occurring in alkaline KOH solution on the nickel foam/palladium/carbon nanofibers (Ni/Pd/CNF) composite electrodes is examined. The layered Ni/Pd/CNF electrodes were prepared by a two-step method consisting of chemical deposition of a thin layer of palladium on the nickel foam support to form Ni/Pd electrode followed by coating the palladium layer with carbon nanofibers layer by means of the CVD method. The scanning electron microscope was used for studying the morphology of both the palladium and carbon layer. The process of hydrogen sorption/desorption into/from Ni/Pd as well as Ni/Pd/CNF electrode was examined using the cyclic voltammetry method. The amount of hydrogen stored in both types of composite electrodes was shown to increase on lowering the potential of hydrogen sorption. The mechanism of the anodic desorption of hydrogen changes depending on whether or not CNF layer is present on the Pd surface. The anodic peak corresponding to the removal of hydrogen from palladium is lower for Ni/Pd/CNF electrode as compared to that measured for Ni/Pd one due to a partial screening of the Pd surface area by CNF layer. The important feature of Ni/Pd/CNF electrode is anodic peak appearing on voltammetric curves at potential ca. 0.4 V more positive than the peak corresponding to hydrogen desorption from palladium. The obtained results showed that upon storing the hydrogen saturated Ni/Pd/CNF electrode at open circuit potential, diffusion of hydrogen from carbon to palladium phase occurs due to interaction between carbon fibers and Pd sites on the nickel foam support

Evidence for hydrogen-assisted recovery of cold-worked palladium: hydrogen solubility and mechanical properties studies

Directory of Open Access Journals (Sweden)

Maria Ferrer

2017-07-01

Full Text Available The influence of hydrogen as an agent to accelerate the thermal recovery of cold-worked palladium has been investigated. The techniques used to characterize the effects of hydrogen on the thermal recovery of palladium were hydrogen solubility and mechanical property measurements. Results show that the presence of modest amounts of hydrogen during annealing of cold-worked palladium does enhance the degree of thermal recovery, with a direct correlation between the amount of hydrogen during annealing and the degree of recovery. The results indicate that the damage resulting from cold-working palladium can be more effectively and efficiently reversed by suitable heat treatments in the presence of appropriate amounts of hydrogen, as compared to heat treatment in vacuum. The somewhat novel technique of using changes in the hydrogen solubility of palladium as an indicator of thermal recovery has been validated and complements the more traditional technique of mechanical property measurements.

STRUCTURAL INTERACTIONS OF HYDROGEN WITH BULK AMORPHOUS MICROSTRUCTURES IN METALLIC SYSTEMS UNDERSTANDING THE ROLE OF PARTIAL CRYSTALLINITY ON PERMEATION AND EMBRITTLEMENT

Energy Technology Data Exchange (ETDEWEB)

Brinkman, Kyle; Fox, Elise; Korinko, Paul; Adams, Thad

2010-05-10

The development of metallic glasses in bulk form has led to a resurgence of interest into the utilization of these materials for a variety of applications. A potentially exciting application for these bulk metallic glass (BMG) materials is their use as composite membranes to replace high cost Pd/Pd-alloy membranes for enhanced gas separation processes. One of the major drawbacks to the industrial use of Pd/Pd-alloy membranes is that during cycling above and below a critical temperature an irreversible change takes place in the palladium lattice structure which can result in significant damage to the membrane. Furthermore, the cost associated with Pd-based membranes is a potential detractor for their continued use and BMG alloys offer a potentially attractive alternative. Several BMG alloys have been shown to possess high permeation rates, comparable to those measured for pure Pd metal. In addition, high strength and toughness when either in-situ or ex-situ second phase dispersoids are present. Both of these properties, high permeation and high strength/toughness, potentially make these materials attractive for gas separation membranes that could resist hydrogen 'embrittlement'. However, a fundamental understanding of the relationship between partially crystalline 'structure'/devitrification and permeation/embrittlement in these BMG materials is required in order to determine the operating window for separation membranes and provide additional input to the material synthesis community for improved alloy design. This project aims to fill the knowledge gap regarding the impact of crystallization on the permeation properties of metallic glass materials. The objectives of this study are to (i) determine the crystallization behavior in different gas environments of Fe and Zr based commercially available bulk metallic glass and (ii) quantify the effects of partial crystallinity on the hydrogen permeation properties of these metallic glass membranes.

Arsenic (III Adsorption Using Palladium Nanoparticles from Aqueous Solution

Directory of Open Access Journals (Sweden)

Farzaneh Arsiya

2017-07-01

Full Text Available The presence of Arsenic in drinking water is the greatest threat to health effects especially in water. The purpose of this study is application of green palladium nanoparticles for removal of trivalent Arsenic from aqueous solutions and also the impact of some factors such as retention time, pH, concentration of palladium nanoparticles and Arsenic concentrations was studied. The values for Arsenic removal from aqueous solutions were measured by furnace atomic adsorption spectrometry (Conter AA700. In the study, Langmuir and Freundlich isotherm models and pseudo-second order kinetic model were studied. The results of  optimization is shown that 0.5 g of nanoparticles can removed %99.8 of Arsenic with initial concentration of  0.5 g/l, in 5 minutes at pH=4. Langmuir model, Freundlich model (R2=0.94 and pseudo-second order kinetic model (R2=0.99 shown high correlation for removing of Arsenic from aqueous solutions. It was found, palladium nanoparticles can be used as an efficient method to remove Arsenic from aqueous solutions in a short time.

γ-Diimine palladium(II based complexes mediated polymerization of methyl methacrylate

Directory of Open Access Journals (Sweden)

Mahmoud Sunjuk

2017-02-01

Full Text Available The synthesis of new palladium(II complexes of the type [Pd(A–NC–ph–CN–ACl2] (4a–e (A = cyclohexyl (a, 2-isoprpropyl (b, pyrenyl (c, naphthyl (d, and 2,6-diisopropyl (e is described. The isolated γ-diimine ligands and their corresponding palladium(II complexes were characterized by their physical properties, elemental analysis, 1H NMR-, 13C NMR, and infrared spectroscopy. The palladium(II complexes (4a–e were employed successfully as catalysts for atom transfer radical polymerization (ATRP of methyl methacrylate (MMA in the presence of ethyl-2-bromoisobutyrate (EBIB as initiator at 90 °C. Polymerization with these catalyst systems afforded polymers with low molecular weight distribution (Mw/Mn and syndio-rich atactic poly (MMA with relatively higher [rr] diads.

Investigation of mechanical and structural characteristics of platinum and palladium at high temperatures

Energy Technology Data Exchange (ETDEWEB)

Trumie, B. T.; Gomidzelovie, L.; Marjanovic, S. R.; Krstic, V. R.

2015-03-30

In order to broaden future application of products based on platinum and palladium a comparative analysis of their high-temperature mechanical properties was performed. Platinum and palladium are of great importance and are widely used in chemical industry, electronics, for making laboratory dishes, to name a few. Mechanical properties of pure metals, such as: tensile strength, creep rate and rupture time were investigated using universal testing machine for tensile testing of materials. Microstructure of samples was investigated by optical microscopy. Based on obtained results it can be concluded that the platinum, compared to palladium, is superior for high-temperature applications. (Author)

Investigation of mechanical and structural characteristics of platinum and palladium at high temperatures

International Nuclear Information System (INIS)

Trumie, B. T.; Gomidzelovie, L.; Marjanovic, S. R.; Krstic, V. R.

2015-01-01

In order to broaden future application of products based on platinum and palladium a comparative analysis of their high-temperature mechanical properties was performed. Platinum and palladium are of great importance and are widely used in chemical industry, electronics, for making laboratory dishes, to name a few. Mechanical properties of pure metals, such as: tensile strength, creep rate and rupture time were investigated using universal testing machine for tensile testing of materials. Microstructure of samples was investigated by optical microscopy. Based on obtained results it can be concluded that the platinum, compared to palladium, is superior for high-temperature applications. (Author)

Some remarks on the neutron elastic- and enelastic-scattering cross sections of palladium

International Nuclear Information System (INIS)

Chiba, S.; Guenther, P.T.; Smith, A.B.

1989-05-01

The cross sections for the elastic-scattering of 5.9, 7.1 and 8.0 MeV neutrons from elemental palladium were measured at forty scattering angles distributed between ∼15/degree/ and 160/degree/. The inelastic-scattering cross sections for the excitation of palladium levels at energies of 260 keV to 560 keV were measured with high resolution at the same energies, and at a scattering angle of 80/degree/. The experimental results were combined with lower-energy values previously obtained by this group to provide a comprehensive data base extending from near the inelastic-scattering threshold to 8 MeV. That data base was interpreted in terms of a coupled-channel model, including the inelastic excitation of one- and two-phonon vibrational levels of the even isotopes of palladium. It was concluded that the palladium inelastic-scattering cross section, at the low energies of interest in assessment of fast-fission-reactor performance, are large (∼50% greater than given in widely used evaluated fission-product data files). They primarily involve compound-nucleus processes, with only a small direct-reaction component attributable to the excitation of the one-phonon, 2 + , vibrational levels of the even isotopes of palladium. 24 refs., 6 figs

Functionalized Palladium Nanoparticles for Hydrogen Peroxide Biosensor

Directory of Open Access Journals (Sweden)

H. Baccar

2011-01-01

Full Text Available We present a comparison between two biosensors for hydrogen peroxide (H2O2 detection. The first biosensor was developed by the immobilization of Horseradish Peroxidase (HRP enzyme on thiol-modified gold electrode. The second biosensor was developed by the immobilization of cysteamine functionalizing palladium nanoparticles on modified gold surface. The amino groups can be activated with glutaraldehyde for horseradish peroxidase immobilization. The detection of hydrogen peroxide was successfully observed in PBS for both biosensors using the cyclic voltammetry and the chronoamperometry techniques. The results show that the limit detection depends on the large surface-to-volume ratio attained with palladium nanoparticles. The second biosensor presents a better detection limit of 7.5 μM in comparison with the first one which is equal to 75 μM.

Palladium-catalysed arylation of sulfonamide stabilised enolates

CSIR Research Space (South Africa)

Zeevaart, JG

2005-03-07

Full Text Available Alpha-Arylation of inethanesulfonamides using palladium catalysis is described. For example, treatment of N-benzyl-Nmethylmethanesulfonamide with catalytic Pd (OAc) (2) in the presence of sodium tert-butoxide, triphenylphosphine and toluene afforded...

Effect of surface treatment on the interfacial contact resistance and corrosion resistance of Fe–Ni–Cr alloy as a bipolar plate for polymer electrolyte membrane fuel cells

International Nuclear Information System (INIS)

Yang, Meijun; Zhang, Dongming

2014-01-01

The bipolar plate is an important component of the PEMFC (polymer electrolyte membrane fuel cell) because it supplies the pathway of electron flow between each unit cell. Fe–Ni–Cr alloy is considered as a good candidate material for bipolar plate, but it is limited to use as a bipolar plate due to its high ICR (interfacial contact resistance) and corrosion problem. In order to explore a cost-effective method on surface modification, various chemical and electrochemical treatments are performed on Fe–Ni–Cr alloy to acquire the effect of the surface modification on the ICR and corrosion behavior. The ICR and corrosion resistance of Fe–Ni–Cr alloy can be effectively controlled by the chemical treatment of immersion in the mixed acid solution with 10 vol% HNO 3 , 2 vol% HCl and 1 vol% HF for 10 min at 65 °C and then was placed in 30 vol% HNO 3 solution for 5 min. The chemical treatment is more effective on reducing ICR and improving corrosion resistance than that of electrochemical methods (be carried out in the 2 mol/L H 2 SO 4 solution with the electrical potential from −0.4 V to 0.6 V) for Fe–Ni–Cr alloy as a bipolar plate for polymer electrolyte membrane fuel cells. - Highlights: • The procedure of the surface treatments on Fe–Ni–Cr alloy as bipolar plate was described in detail. • Effects of various surface treatments on the interfacial contact resistivity and corrosion behavior were discussed. • The mechanism of the surface modification was particularly analyzed

HE3 outgassing from four working palladium and uranium beds

International Nuclear Information System (INIS)

Souers, P. C.; Coronado, P. R.; Fearon, F. M.; Garza, R. G.; Shaw , J. F.; Stump, R. K.; Tsugawa, R. T.

1988-01-01

The He 3 output from two palladium and two uranium beds storing T 2 and D-T was studied as a function of time. Three of the beds were started new and watched for a year; the fourth bed was twelve years old. All four were beds used in routine tritium handling. Initial stoichiometries were PdT/sub 0.3/ and UT/sub 0.7/ so that both operated at similar 1 to 130 kPa pressures. The He 3 from palladium ranged from the 0.002 mo1% lower level of sensitivity to 0.01% for PdT 2 at one year of age. The UT system showed 0.1% He 3 at 4 to 62 days and 0.1 to 10% at longer times, with the first cuts being high in He 3 . The palladium bed with 95 to 97% pure T 2 enriches the output to as high as 97 to 99%. 9 refs., 1 fig., 2 tabs

Noise temperature measurements for the determination of the thermodynamic temperature of the melting point of palladium

Energy Technology Data Exchange (ETDEWEB)

Edler, F.; Kuhne, M.; Tegeler, E. [Bundesanstalt Physikalisch-Technische, Berlin (Germany)

2004-02-01

The thermodynamic temperature of the melting point of palladium in air was measured by noise thermometric methods. The temperature measurement was based on noise comparison using a two-channel arrangement to eliminate parasitic noises of electronic components by cross correlation. Three miniature fixed points filled with pure palladium (purity: {approx}99.99%, mass: {approx}90 g) were used to realize the melts of the fixed point metal. The measured melting temperature of palladium in air amounted to 1552.95 deg C {+-} 0.21 K (k = 2). This temperature is 0.45 K lower than the temperature of the melting point of palladium measured by radiation thermometry. (authors)

Preparation of palladium impregnated alumina adsorbents: Thermal and neutron activation analysis

Energy Technology Data Exchange (ETDEWEB)

Mukherjee, Sumanta; Gupta, N.K.; Roy, S.P.; Dash, S.; Kumar, A.; Bamankar, Y.R.; Rao, T.V. Vittal [Product Development Division, Bhabha Atomic Research Centre, Mumbai 400085 (India); Kumar, N. [Fuel Chemistry Division, Bhabha Atomic Research Centre, Mumbai 400085 (India); Naik, Y., E-mail: ynaik@barc.gov.in [Product Development Division, Bhabha Atomic Research Centre, Mumbai 400085 (India)

2016-02-10

Highlights: • Pd/Al{sub 2}O{sub 3} composite microspheres particles with high surface area were prepared sol–gel process. • Scanning electron microscopy (SEM) studies on silver coated particle. • Content of the palladium was determined using Neutron Activation Analysis (NAA). • Decomposition study has been done by quadrupole mass analyser. - Abstract: Pd/Al{sub 2}O{sub 3} composite microspheres particles with high surface area were prepared sol–gel process. The decomposition of dried gel-particles was studied by TGA/DTA and FT-IR technique. TGA studies indicated that formation of palladium is marked by a broad exothermic peak with a loss of water and oxidation of trapped HMTA/Urea nitrate mixture. The main decomposition reaction took place in the temperature range of 660–1250 K in helium and relatively lower temperature of 400 K to 1250 K in oxygen. Optical microscopy indicated that the distribution of palladium is uniform. SEM studies on silver coated particle indicated that there was surface erosion of some gel spheres while in few of them micro cracks were seen at high resolution. Content of the palladium was determined using Neutron Activation Analysis (NAA). Decomposition at various temperatures was studied using Residual gas analyser and decomposition species were identified using quadrupole mass analyser.

Development of a second generation palladium-catalyzed cycloalkenylation and its application to bioactive natural product synthesis.

Science.gov (United States)

Toyota, Masahiro

2013-07-01

A novel palladium-catalyzed intramolecular oxidative alkylation of unactivated olefins is described. This protocol was devised to solve one of the drawbacks of the original palladium-catalyzed cycloalkenylation that we developed. We call this new procedure the 'second generation palladium-catalyzed cycloalkenylation'. This protocol has been applied to the total syntheses of cis-195A, trans-195A, boonein, scholareins A, C, D, and alpha-skytanthine.

Palladium-Catalyzed Asymmetric Quaternary Stereocenter Formation

NARCIS (Netherlands)

Gottumukkala, Aditya L.; Matcha, Kiran; Lutz, Martin; de Vries, Johannes G.; Minnaard, Adriaan J.

2012-01-01

An efficient palladium catalyst is presented for the formation of benzylic quaternary stereocenters by conjugate addition of arylboronic acids to a variety of beta,beta-disubstituted carbocyclic, heterocyclic, and acyclic enones. The catalyst is readily prepared from PdCl2, PhBOX, and AgSbF6, and

Palladium-catalyzed asymmetric quaternary stereocenter formation

NARCIS (Netherlands)

Gottumukkala, A.L.; Matcha, K.; Lutz, M.; de Vries, J.G.; Minnaard, A.J.

2012-01-01

An efficient palladium catalyst is presented for the formation of benzylic quaternary stereocenters by conjugate addition of arylboronic acids to a variety of β,β-disubstituted carbocyclic, heterocyclic, and acyclic enones. The catalyst is readily prepared from PdCl2, PhBOX, and AgSbF6, and provides

Extracellular Palladium Nanoparticle Production using Geobacter sulfurreducens

KAUST Repository

Yates, Matthew D.

2013-09-03

Sustainable methods are needed to recycle precious metals and synthesize catalytic nanoparticles. Palladium nanoparticles can be produced via microbial reduction of soluble Pd(II) to Pd(0), but in previous tests using dissimilatory metal reducing bacteria (DMRB), the nanoparticles were closely associated with the cells, occupying potential reductive sites and eliminating the potential for cell reuse. The DMRB Geobacter sulfurreducens was shown here to reduce soluble Pd(II) to Pd(0) nanoparticles primarily outside the cell, reducing the toxicity of metal ions, and allowing nanoparticle recovery without cell destruction that has previously been observed using other microorganisms. Cultures reduced 50 ± 3 mg/L Pd(II) with 1% hydrogen gas (v/v headspace) in 6 h incubation tests [100 mg/L Pd(II) initially], compared to 8 ± 3 mg/L (10 mM acetate) without H2. Acetate was ineffective as an electron donor for palladium removal in the presence or absence of fumarate as an electron acceptor. TEM imaging verified that Pd(0) nanoparticles were predominantly in the EPS surrounding cells in H2-fed cultures, with only a small number of particles visible inside the cell. Separation of the cells and EPS by centrifugation allowed reuse of the cell suspensions and effective nanoparticle recovery. These results demonstrate effective palladium recovery and nanoparticle production using G. sulfurreducens cell suspensions and renewable substrates such as H2 gas. © 2013 American Chemical Society.

COST-EFFECTIVE METHOD FOR PRODUCING SELF SUPPORTED PALLADIUM ALLOY MEMBRANES FOR USE IN EFFICIENT PRODUCTION OF COAL DERIVED HYDROGEN

Energy Technology Data Exchange (ETDEWEB)

B. Lanning; J. Arps

2005-08-31

Efforts in this quarter were concentrated on developing vacuum processing procedures to produce thinner (<4 {micro}m-thick), defect-free films over larger areas (>100 cm{sup 2}). We continued to test three different types of rigid supporting substrates, thermally oxidized silicon (10 cm diameter), polished borosilicate glass (10 cm diameter), and soda-lime glass (>100 cm{sup 2} areas), each representing a different cost, surface roughness, and chemistry. Mechanical integrity, defect density, and release characteristics of the films, though similar for the oxidized silicon and borosilicate glass, were distinctly different for the inexpensive soda-lime (float) glass; i.e., more sensitive to surface impurities. In general, films less than 4 {micro}m-thick were shown to be very sensitive to surface condition of the supporting substrate, particularly in the case of the soda-lime glass, to the point where surface strain overrode and dominated the intrinsic bulk stresses that are produced during the growth process. Therefore, in the near term (over the next quarter), large area films (>100 cm{sup 2}) will be produced at a minimum thickness of 5 {micro}m while further development will be conducted in subsequent quarters to reduce membrane thickness in large area films. Continued hydrogen permeation experiments and characterization of 5 and 10 {micro}m-thick, Pd-Cu films, with compositions near the 60/40 (Pd/Cu phase boundary) in combination with air oxidation treatments to improve performance. Pure hydrogen permeability for an as-received, 5 {micro}m film at 400 C was determined to be 1.3 x 10{sup -4} cm{sup 3}(STP) {center_dot} cm/cm{sup 2} {center_dot} s {center_dot} cmHg{sup 0.5} at steady state. Even a membrane {approx} 10 {micro}m-thick, exhibited a steady state hydrogen flux of 32 cm{sup 3}(STP)/cm{sup 2}min after air exposure, which, when normalized for DOE's Office of Fossil Energy's specified hydrogen flux with a {Delta}P of 100 psi and a permeate

Palladium based membranes and membrane reactors for hydrogen production and purification : An overview of research activities at Tecnalia and TU/e

NARCIS (Netherlands)

Fernandez, E.; Helmi Siasi Farimani, A.; Medrano Jimenez, J.A.; Coenen, K.T.; Arratibel Plazaola, A.; Melendez Rey, J.; de Nooijer, N.C.A.; Viviente, J.L.; Zuniga, J.; van Sint Annaland, M.; Gallucci, F.; Pacheco Tanaka, D.A.

2017-01-01

In this paper, the main achievements of several European research projects on Pd based membranes and Pd membrane reactors for hydrogen production are reported. Pd-based membranes have received an increasing interest for separation and purification of hydrogen. In addition, the integration of such

Stereoselective synthesis of tricyclic compounds by intramolecular palladium-catalyzed addition of aryl iodides to carbonyl groups

Directory of Open Access Journals (Sweden)

Jakub Saadi

2016-06-01

Full Text Available Starting from γ-ketoesters with an o-iodobenzyl group we studied a palladium-catalyzed cyclization process that stereoselectively led to bi- and tricyclic compounds in moderate to excellent yields. Four X-ray crystal structure analyses unequivocally defined the structure of crucial cyclization products. The relative configuration of the precursor compounds is essentially transferred to that of the products and the formed hydroxy group in the newly generated cyclohexane ring is consistently in trans-arrangement with respect to the methoxycarbonyl group. A transition-state model is proposed to explain the observed stereochemical outcome. This palladium-catalyzed Barbier-type reaction requires a reduction of palladium(II back to palladium(0 which is apparently achieved by the present triethylamine.

Anionic Palladium(0) and Palladium(II) Ate Complexes.

Science.gov (United States)

Kolter, Marlene; Böck, Katharina; Karaghiosoff, Konstantin; Koszinowski, Konrad

2017-10-16

Palladium ate complexes are frequently invoked as important intermediates in Heck and cross-coupling reactions, but so far have largely eluded characterization at the molecular level. Here, we use electrospray-ionization mass spectrometry, electrical conductivity measurements, and NMR spectroscopy to show that the electron-poor catalyst [L 3 Pd] (L=tris[3,5-bis(trifluoromethyl)phenyl]phosphine) readily reacts with Br - ions to afford the anionic, zero-valent ate complex [L 3 PdBr] - . In contrast, more-electron-rich Pd catalysts display lower tendencies toward the formation of ate complexes. Combining [L 3 Pd] with LiI and an aryl iodide substrate (ArI) results in the observation of the Pd II ate complex [L 2 Pd(Ar)I 2 ] - . © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

Preparation of a Bimetal Using Mechanical Alloying for Environmental or Industrial Use

Science.gov (United States)

Quinn, Jacqueline; Geiger, Cherie; Clausen, Christian

2013-01-01

Following the 1976 Toxic Substances Control Act ban on their manufacture, PCBs remain an environmental threat. PCBs are known to bio-accumulate and concentrate in fatty tissues. Further complications arise from the potential for contamination of commercial mixtures with other more toxic chlorinated compounds such as polychlorinated dibenzodioxins (PCDDs) and polychlorinated dibenzofurans (PCDFs). Until recently, only one option was available for the treatment of PCB-contaminated materials: incineration. This may prove to be more detrimental to the environment than the PCBs themselves due to the potential for formation of PCDDs. Metals have been used for the past ten years for the remediation of halogenated solvents and other contaminants in the environment; however, zero-valent metals alone do not possess the activity required to dehalogenate PCBs. Palladium has been shown to act as an excellent catalyst for the dechlorination of PCBs with active metals. This invention is a method for the production of a palladium/magnesium bimetal capable of dechlorinating PCBs using mechanical milling/mechanical alloying. Other base metals and catalysts may also be alloyed together (e.g., nickel or zinc) to create a similarly functioning catalyst system. Several bimetal catalyst systems currently can be used for processes such as hydrogen peroxide synthesis, oxidation of ethane, selective oxidation, hydrogenation, and production of syngas for further conversion to clean fuels. The processes for making these bimetal catalysts often involve vapor deposition. This technology provides an alternative to vapor deposition that may provide equally active catalysts. 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. The mechanical milling technique is

Development of tantalum–zirconium alloy for hydrogen purification

Energy Technology Data Exchange (ETDEWEB)

Kumar, Sanjay, E-mail: sanjay.barc@gmail.com [Fusion Reactor Materials Section, MG, BARC, Mumbai 85 (India); IAMR, Hiroshima University, Higashihiroshima 739-8530 (Japan); Singh, Anamika [GSASM Hiroshima University, Higashihiroshima 739-8530 (Japan); Jain, Uttam; Dey, Gautam Kumar [Fusion Reactor Materials Section, MG, BARC, Mumbai 85 (India)

2016-11-01

Highlights: • Terminal solid solubility of Ta increases with Zr addition. • Increase in lattice parameters of Ta due to Zr addition may be the possible reason. • Enhance H solubility could also be explained on the change in e-DOS of Ta–Zr alloys. • Ta–Zr alloys could be possible combination for hydrogen purification membrane. - Abstract: Terminal solid solubility of hydrogen in Ta–Zr alloys has been studied in connection with the development of tantalum based metallic membrane for hydrogen/tritium purification. The alloys were prepared by vacuum arc melting technique and subsequently cold rolled to 0.2 mm thickness. The terminal solid solubility of hydrogen in these cold rolled samples was investigated in a modified Sieverts apparatus. The terminal solid solubility of hydrogen was marginally increased with zirconium content. The change in the lattices parameter of tantalum upon zirconium addition and the higher affinity of zirconium for hydrogen as compared to tantalum could be the possible reasons.

Morphological Study Of Palladium Thin Films Deposited By Sputtering

Energy Technology Data Exchange (ETDEWEB)

Salcedo, K L; Rodriguez, C A [Grupo Plasma Laser y Aplicaciones, Ingenieria Fisica, Universidad Tecnologica de Pereira (Colombia); Perez, F A [WNANO, West Virginia University (United States); Riascos, H [Grupo Plasma Laser y Aplicaciones, Departamento de Fisica, Universidad Tecnologica de Pereira (Colombia)

2011-01-01

This paper presents a morphological analysis of thin films of palladium (Pd) deposited on a substrate of sapphire (Al{sub 2}O{sub 3}) at a constant pressure of 3.5 mbar at different substrate temperatures (473 K, 523 K and 573 K). The films were morphologically characterized by means of an Atomic Force Microscopy (AFM); finding a relation between the roughness and the temperature. A morphological analysis of the samples through AFM was carried out and the roughness was measured by simulating the X-ray reflectivity curve using GenX software. A direct relation between the experimental and simulation data of the Palladium thin films was found.

Morphological Study Of Palladium Thin Films Deposited By Sputtering

International Nuclear Information System (INIS)

Salcedo, K L; Rodriguez, C A; Perez, F A; Riascos, H

2011-01-01

This paper presents a morphological analysis of thin films of palladium (Pd) deposited on a substrate of sapphire (Al 2 O 3 ) at a constant pressure of 3.5 mbar at different substrate temperatures (473 K, 523 K and 573 K). The films were morphologically characterized by means of an Atomic Force Microscopy (AFM); finding a relation between the roughness and the temperature. A morphological analysis of the samples through AFM was carried out and the roughness was measured by simulating the X-ray reflectivity curve using GenX software. A direct relation between the experimental and simulation data of the Palladium thin films was found.

Supported palladium nanoparticles synthesized by living plants as a catalyst for Suzuki-Miyaura reactions.

Directory of Open Access Journals (Sweden)

Helen L Parker

Full Text Available The metal accumulating ability of plants has previously been used to capture metal contaminants from the environment; however, the full potential of this process is yet to be realized. Herein, the first use of living plants to recover palladium and produce catalytically active palladium nanoparticles is reported. This process eliminates the necessity for nanoparticle extraction from the plant and reduces the number of production steps compared to traditional catalyst palladium on carbon. These heterogeneous plant catalysts have demonstrated high catalytic activity in Suzuki coupling reactions between phenylboronic acid and a range of aryl halides containing iodo-, bromo- and chloro- moieties.

Superconductivity and the structural phase transitions in palladium hydride and palladium deuteride

International Nuclear Information System (INIS)

Standley, R.W.

1980-01-01

The results of two experimental studies of the superconducting transition temperature, T/sub c/, of palladium hydride, PdH/sub x/, and palladium deuteride, PdD/sub x/, are presented. In the first study, the superconducting transition temperature of PdH/sub x/(D/sub x/) is studied as a function of H(D) concentration, x, in the temperature range from 0.2 K to 4K. The data join smoothly with those reported previously by Miller and Satterthwaite at higher temperatures, and the composite data are described by the empirical relation T/sub c/ = 150.8 (x-x/sub o/) 2 244 , where x/sub o/ = 0.715 for hydride samples and 0.668 for deuteride samples. The results, when compared with the theoretical predictions of Klein and Papaconstantopoulos, et al., raise questions about the validity of their explanation of the reverse isotope effect, which is based solely on a difference in force constants. In the second study, the effect of the order-disorder structural transition associated with the 50 K anomaly on the superconductivity of PdH/sub x/(D/sub x/) is investigated. Samples were quenched to low temperatures in the disordered state, and their transition temperatures measured. The samples were then annealed just below the anomaly temperature, and the ordering process followed by monitoring the change in sample resistance. The transition temperatures in the ordered state were then measured

A dataset for preparing pristine graphene-palladium nanocomposites using swollen liquid crystal templates

Science.gov (United States)

Vats, Tripti; Siril, Prem Felix

2017-12-01

Pristine graphene (G) has not received much attention as a catalyst support, presumably due to its relative inertness as compared to reduced graphene oxide (RGO). In the present work, we used swollen liquid crystals (SLCs) as nano-reactors for graphene-palladium nanocomposites synthesis. The 'soft' confinement of SLCs directs the growth of palladium (Pd) nanoparticles over the G sheets. In this dataset we include all the parameters and details of different techniques used for the characterization of G, SLCs and synthesized G-Pd nanocomposites. The synthesized G-palladium nanocomposites (Pd-G) exhibited improved catalytic activity compared with Pd-RGO and Pd nanoparticles, in the hydrogenation of nitrophenols and C-C coupling reactions.

Morphology controlled graphene-alloy nanoparticle hybrids with tunable carbon monoxide conversion to carbon dioxide.

Science.gov (United States)

Devi, M Manolata; Dolai, N; Sreehala, S; Jaques, Y M; Mishra, R S Kumar; Galvao, Douglas S; Tiwary, C S; Sharma, Sudhanshu; Biswas, Krishanu

2018-05-10

Selective oxidation of CO to CO2 using metallic or alloy nanoparticles as catalysts can solve two major problems of energy requirements and environmental pollution. Achieving 100% conversion efficiency at a lower temperature is a very important goal. This requires sustained efforts to design and develop novel supported catalysts containing alloy nanoparticles. In this regard, the decoration of nanoalloys with graphene, as a support for the catalyst, can provide a novel structure due to the synergic effect of the nanoalloys and graphene. Here, we demonstrate the effect of nano-PdPt (Palladium-Platinum) alloys having different morphologies on the catalytic efficiency for the selective oxidation of CO. Efforts were made to prepare different morphologies of PdPt alloy nanoparticles with the advantage of tuning the capping agent (PVP - polyvinyl pyrollidone) and decorating them on graphene sheets via the wet-chemical route. The catalytic activity of the G-PdPt hybrids with an urchin-like morphology has been found to be superior (higher % conversion at 135 °C lower) to that with a nanoflower morphology. The above experimental observations are further supported by molecular dynamics (MD) simulations.

Fabrication and characterization of a flow-through nanoporous gold nanowire/AAO composite membrane

Energy Technology Data Exchange (ETDEWEB)

Liu, L; Lee, W; Huang, Z; Scholz, R; Goesele, U [Max Planck Institute of Microstructure Physics, Weinberg 2, D-06120 Halle (Germany)

2008-08-20

The fabrication of a composite membrane of nanoporous gold nanowires and anodic aluminum oxide (AAO) is demonstrated by the electrodeposition of Au-Ag alloy nanowires into an AAO membrane, followed by selective etching of silver from the alloy nanowires. This composite membrane is advantageous for flow-through type catalytic reactions. The morphology evolution of the nanoporous gold nanowires as a function of the diameter of the Au-Ag nanowire 'precursors' is also investigated.

Fabrication and characterization of a flow-through nanoporous gold nanowire/AAO composite membrane

International Nuclear Information System (INIS)

Liu, L; Lee, W; Huang, Z; Scholz, R; Goesele, U

2008-01-01

The fabrication of a composite membrane of nanoporous gold nanowires and anodic aluminum oxide (AAO) is demonstrated by the electrodeposition of Au-Ag alloy nanowires into an AAO membrane, followed by selective etching of silver from the alloy nanowires. This composite membrane is advantageous for flow-through type catalytic reactions. The morphology evolution of the nanoporous gold nanowires as a function of the diameter of the Au-Ag nanowire 'precursors' is also investigated

Fabrication and characterization of a flow-through nanoporous gold nanowire/AAO composite membrane.

Science.gov (United States)

Liu, L; Lee, W; Huang, Z; Scholz, R; Gösele, U

2008-08-20

The fabrication of a composite membrane of nanoporous gold nanowires and anodic aluminum oxide (AAO) is demonstrated by the electrodeposition of Au-Ag alloy nanowires into an AAO membrane, followed by selective etching of silver from the alloy nanowires. This composite membrane is advantageous for flow-through type catalytic reactions. The morphology evolution of the nanoporous gold nanowires as a function of the diameter of the Au-Ag nanowire 'precursors' is also investigated.

One-Pot Synthesis of Hierarchical Flower-Like Pd-Cu Alloy Support on Graphene Towards Ethanol Oxidation

Science.gov (United States)

Zhang, Jingyi; Feng, Anni; Bai, Jie; Tan, Zhibing; Shao, Wenyao; Yang, Yang; Hong, Wenjing; Xiao, Zongyuan

2017-09-01

The synergetic effect of alloy and morphology of nanocatalysts play critical roles towards ethanol electrooxidation. In this work, we developed a novel electrocatalyst fabricated by one-pot synthesis of hierarchical flower-like palladium (Pd)-copper (Cu) alloy nanocatalysts supported on reduced graphene oxide (Pd-Cu(F)/RGO) for direct ethanol fuel cells. The structures of the catalysts were characterized by using scanning electron microscopy (SEM), transmission electron microscope (TEM), X-ray diffraction (XRD), and X-ray photoelectron spectrometer (XPS). The as-synthesized Pd-Cu(F)/RGO nanocatalyst was found to exhibit higher electrocatalytic performances towards ethanol electrooxidation reaction in alkaline medium in contrast with RGO-supported Pd nanocatalyst and commercial Pd black catalyst in alkaline electrolyte, which could be attributed to the formation of alloy and the morphology of nanoparticles. The high performance of nanocatalyst reveals the great potential of the structure design of the supporting materials for the future fabrication of nanocatalysts.

Camphyl-based α-diimine palladium complexes: highly efficient precatalysts for direct arylation of thiazoles in open-air.

Science.gov (United States)

Chen, Fu-Min; Lu, Dong-Dong; Hu, Li-Qun; Huang, Ju; Liu, Feng-Shou

2017-07-21

Based on the strategy of the development of phosphine-free palladium-catalyzed direct C-H arylation, a series of camphyl-based α-diimine palladium complexes bearing sterically bulky substituents were synthesized and characterized. The palladium complexes were applied for the cross-coupling of thiazole derivatives with aryl bromides. The effect of the sterically bulky substituent on the N-aryl moiety as well as the reaction conditions was screened. Under the optimal protocols, a wide range of aryl bromides can be smoothly coupled with thiazoles in good to excellent yields in the presence of a low palladium loading of 0.2 mol% under open-air conditions.

Influence of shape and finishing on the corrosion of palladium-based dental alloys

NARCIS (Netherlands)

Milheiro, A.; Muris, J.; Kleverlaan, C.J.; Feilzer, A.J.

2015-01-01

PURPOSE: The purpose of this study was to evaluate the effects of the surface treatment and shape of the dental alloy on the composition of the prosthetic work and its metallic ion release in a corrosive medium after casting. MATERIALS AND METHODS: Orion Argos (Pd-Ag) and Orion Vesta (Pd-Cu) were

In-situ observation of deuteride formation in palladium electrochemical cathode by X-ray diffraction method

International Nuclear Information System (INIS)

Yamamoto, Takao; Oka, Takashi; Taniguchi, Ryoichi

1990-01-01

In-situ X-ray diffraction observation of palladium foil cathode (10 μm) was carried out during electrolysis of 0.1N-LiOD heavy water solution in order to estimate the deuterium content in palladium during the detection of charged particles in our previous work. A complete transformation into β-palladium deuteride phase was observed, and its maximum lattice constant 4.06 A was evaluated as corresponding to D/Pd = 0.73. The deuterium concentration in the previous work was estimated as higher than this considering the difference in cell conditions. (author)

Palladium coated fibre Bragg grating based hydrogen sensor

International Nuclear Information System (INIS)

Kasinathan, M.; Sosamma, S.; Kishore, S.; Elumalai, V.; Krishnan, R.; Babu Rao, C.; Dash, Sitaram; Murali, N.; Jayakumar, T.

2011-01-01

Detection of steam generator leaks in fast nuclear reactors is carried out by monitoring hydrogen in argon cover-gas. Hydrogen released during sodium cleaning of fast reactor components is required to be monitored. Hydrogen sensors with good sensitivity, stability and response time are required for all the above applications. We report a new type of hydrogen sensor with a Fibre Bragg Grating (FBG) coated with palladium thin film which is used to detect the leak of hydrogen gas in the Steam Generator (SG) module of the Fast Breeder Reactor (FBR). If water leaks into sodium, it results in sodium-water reaction. In this reaction hydrogen and sodium hydroxide are formed. Due to the explosive risk of hydrogen system, hydrogen sensors are of great interest in this case. It is known that hydrogen forms an explosive mixture with air once its concentration exceeds beyond the explosion limit of four percent. The advantages of FBG based hydrogen sensor over the other hydrogen sensors are its inherent property of safety from sparking, immunity to ambient electromagnetic interference. The sensing mechanism in this device is based on mechanical strain that is induced in the palladium coating when it absorbs hydrogen. This process physically stretches the grating and causes the grating period and grating's refractive index, to change. The Bragg wavelength shift is directly proportional to the strain induced and can be directly related to the percentage of hydrogen exposure. The online monitoring of palladium thin film coating on FBG is carried out and recorded the wavelength change and strain induced on the FBG. A hydrogen sensor set up have been fabricated which consists of SS vessel of capacity 10 litres, provided with pressure gauge, Argon filling line with a valve, Hydrogen injection line with flange, a vent line with valve and Hydrogen sensor fixing point. The Palladium coated FBG based Hydrogen sensor is tested in this experimental facility in the exposure of hydrogen in

Fabrication of Polybenzimidazole/Palladium Nanoparticles Hollow Fiber Membranes for Hydrogen Purification

KAUST Repository

Villalobos, Luis Francisco; Hilke, Roland; Akhtar, Faheem Hassan; Peinemann, Klaus-Viktor

2017-01-01

in the form of ions that coordinate to the imidazole groups of the polymer. This is attractive for membrane production because agglomeration of nanoparticles is minimized and the high-cost metal is incorporated in only the selective layer—where it is required

Selective electrocatalysis of biofuel molecular oxidation using palladium nanoparticles generated on Shewanella oneidensis MR-1

DEFF Research Database (Denmark)

Wu, Ranran; Tian, Xiaochun; Xiao, Yong

2018-01-01

of formate with 200 mV less over-potential. Notably they show unique selective activity toward electrochemical oxidation of formate, whereas no electrochemical catalysis was found for oxidation of ethanol, methanol and acetate. This work demonstrates a sustainable and low-cost method for producing efficient......Production of molecular scale palladium (Pd) nanoparticles (NPs) is important due to their catalytic function in electrochemical oxidation of a number of core fuel molecules in fuel cells. Biogenic methods offer an economic and environmentally friendly synthesis route. In this work...... membrane surface. Mapping by conductive atomic force microscopy shows that the presence of these PdNPs promotes electron transfer and enhances the electric conductivity of the cells. Compared to electrodeposited PdNPs, PdNPs generated by S. oneidensis MR-1 catalyze electrochemically the oxidation...

Controlled immobilization of palladium nanoparticles in two different fluorinated polymeric aggregate cores and their application in catalysis

DEFF Research Database (Denmark)

Kijima, Tetsushi; Javakhishvili, Irakli; Jankova Atanasova, Katja

2012-01-01

Fluoroalkyl end-capped betaine-type cooligomeric nanocomposites-immobilized palladium nanoparticles were prepared by the reactions of palladium chloride with sodium acetate in the presence of sodium chloride and the corresponding fluorinated cooligomers. Outer blocks of poly(2,3,4,5,6-pentafluoro....... These fluorinated nanocomposites-immobilized palladium nanoparticles were also applied to the catalysts for Suzuki-Miyaura cross-coupling reaction, and the different reactivity between these nanocomposites was observed....

A Facile Synthesis of Hollow Palladium/Copper Alloy Nanocubes Supported on N-Doped Graphene for Ethanol Electrooxidation Catalyst

OpenAIRE

Zhengyu Bai; Rumeng Huang; Lu Niu; Qing Zhang; Lin Yang; Jiujun Zhang

2015-01-01

In this paper, a catalyst of hollow PdCu alloy nanocubes supported on nitrogen-doped graphene support (H-PdCu/ppy-NG) is successfully synthesized using a simple one-pot template-free method. Two other catalyst materials such as solid PdCu alloy particles supported on this same nitrogen-doped graphene support (PdCu/ppy-NG) and hollow PdCu alloy nanocubes supported on the reduced graphene oxide support (H-PdCu/RGO) are also prepared using the similar synthesis conditions for comparison. It is f...

Analysis of the anomalous hydrogen solubilities in deformed palladiums

Energy Technology Data Exchange (ETDEWEB)

Park, Choong Nyeon; Lee, Ho Jong

1987-02-01

The anomalous hydrogen solubilities in the deformed palladiums were analyzed by empolying modified Kirchheim's model with considering the partially coherent strain energy which would induced during hydride precipitation around edge dislocations. The dislocation densities, obtained by this model, of the various cold worked and/or reversible US transformed palladium samples were the order of 10/sup 11/cm/sup -2/. The partially coherent strain energies were about 3 kJ/molH and nearly same in the various samples. This value could be compared with the incoherent strain energy, 0.4kJ/molH, which was obtained from the hysteresis on P-C isotherm, and the coherent strain energy calulated, 9.6kJ/molH.

Refractory metal joining for first wall applications

International Nuclear Information System (INIS)

Cadden, C.H.; Odegard, B.C.

2000-01-01

The potential use of high temperature coolant (e.g. 900 deg. C He) in first wall structures would preclude the applicability of copper alloy heat sink materials and refractory metals would be potential replacements. Brazing trials were conducted in order to examine techniques to join tungsten armor to high tungsten (90-95 wt%) or molybdenum TZM heat sink materials. Palladium-, nickel- and zirconium-based filler metals were investigated using brazing temperatures ranging from 1000 deg. C to 1275 deg. C. Palladium-nickel and palladium-cobalt braze alloys were successful in producing generally sound metallurgical joints in tungsten alloy/tungsten couples, although there was an observed tendency for the pure tungsten armor material to exhibit grain boundary cracking after bonding. The zirconium- and nickel-based filler metals produced defect-containing joints, specifically cracking and porosity, respectively. The palladium-nickel braze alloy produced sound joints in the Mo TZM/tungsten couple. Substitution of a lanthanum oxide-containing, fine-grained tungsten material (for the pure tungsten) eliminated the observed tungsten grain boundary cracking

Refractory metal joining for first wall applications

Energy Technology Data Exchange (ETDEWEB)

Cadden, C.H. E-mail: chcadde@sandia.gov; Odegard, B.C

2000-12-01

The potential use of high temperature coolant (e.g. 900 deg. C He) in first wall structures would preclude the applicability of copper alloy heat sink materials and refractory metals would be potential replacements. Brazing trials were conducted in order to examine techniques to join tungsten armor to high tungsten (90-95 wt%) or molybdenum TZM heat sink materials. Palladium-, nickel- and zirconium-based filler metals were investigated using brazing temperatures ranging from 1000 deg. C to 1275 deg. C. Palladium-nickel and palladium-cobalt braze alloys were successful in producing generally sound metallurgical joints in tungsten alloy/tungsten couples, although there was an observed tendency for the pure tungsten armor material to exhibit grain boundary cracking after bonding. The zirconium- and nickel-based filler metals produced defect-containing joints, specifically cracking and porosity, respectively. The palladium-nickel braze alloy produced sound joints in the Mo TZM/tungsten couple. Substitution of a lanthanum oxide-containing, fine-grained tungsten material (for the pure tungsten) eliminated the observed tungsten grain boundary cracking.

Refractory metal joining for first wall applications

Science.gov (United States)

Cadden, C. H.; Odegard, B. C.

2000-12-01

The potential use of high temperature coolant (e.g. 900°C He) in first wall structures would preclude the applicability of copper alloy heat sink materials and refractory metals would be potential replacements. Brazing trials were conducted in order to examine techniques to join tungsten armor to high tungsten (90-95 wt%) or molybdenum TZM heat sink materials. Palladium-, nickel- and zirconium-based filler metals were investigated using brazing temperatures ranging from 1000°C to 1275°C. Palladium-nickel and palladium-cobalt braze alloys were successful in producing generally sound metallurgical joints in tungsten alloy/tungsten couples, although there was an observed tendency for the pure tungsten armor material to exhibit grain boundary cracking after bonding. The zirconium- and nickel-based filler metals produced defect-containing joints, specifically cracking and porosity, respectively. The palladium-nickel braze alloy produced sound joints in the Mo TZM/tungsten couple. Substitution of a lanthanum oxide-containing, fine-grained tungsten material (for the pure tungsten) eliminated the observed tungsten grain boundary cracking.

Activation and deactivation of neutral palladium(II) phosphinesulfonato polymerization catalysts

KAUST Repository

Rünzi, Thomas

2012-12-10

13C-Labeled ethylene polymerization (pre)catalysts [κ2-(anisyl)2P,O]Pd(13CH3)(L) (1-13CH3-L) (L = pyridine, dmso) based on di(2-anisyl)phosphine benzenesulfonate were used to assess the degree of incorporation of 13CH3 groups into the formed polyethylenes. Polymerizations of variable reaction time reveal that ca. 60-85% of the 13C-label is found in the polymer after already 1 min polymerization time, which provides evidence that the pre-equilibration between the catalyst precursor 1-13CH3-L and the active species 1-13CH3-(ethylene) is fast with respect to chain growth. The fraction of 1-13CH3-L that initiates chain growth is likely higher than the 60-85% determined from the 13C-labeled polymer chain ends since (a) chain walking results in in-chain incorporation of the 13C-label, (b) irreversible catalyst deactivation by formation of saturated (and partially volatile) alkanes diminishes the amount of 13CH3 groups incorporated into the polymer, and (c) palladium-bound 13CH3 groups, and more general palladium-bound alkyl(polymeryl) chains, partially transfer to phosphorus by reductive elimination. NMR and ESI-MS analyses of thermolysis reactions of 1-13CH3-L provide evidence that a mixture of phosphonium salts (13CH3)xP+(aryl)4-x (2-7) is formed in the absence of ethylene. In addition, isolation and characterization of the mixed bis(chelate) palladium complex [κ2-(anisyl)2P,O]Pd[κ2-(anisyl) (13CH3)P,O] (11) by NMR and X-ray diffraction analyses from these mixtures indicate that oxidative addition of phosphonium salts to palladium(0) species is also operative. The scrambling of palladium-bound carbyls and phosphorus-bound aryls is also relevant under NMR, as well as preparative reactor polymerization conditions exemplified by the X-ray diffraction analysis of [κ2-(anisyl)2P,O] Pd[κ2-(anisyl)(CH2CH3)P,O] (12) and [κ2-(anisyl)2P,O]Pd[κ2-(anisyl) ((CH2)3CH3)P,O] (13) isolated from pressure reactor polymerization experiments. In addition, ESI-MS analyses of reactor

Tetradentate N2O2 Chelated Palladium(II Complexes: Synthesis, Characterization, and Catalytic Activity towards Mizoroki-Heck Reaction of Aryl Bromides

Directory of Open Access Journals (Sweden)

Siti Kamilah Che Soh

2013-01-01

Full Text Available Four air and moisture-stable palladium(II-Schiff base complexes, N,N′-bis(α-methylsalicylidenepropane-1,3-diamine palladium(II (2a, N,N′-bis(4-methyl-α-methylsalicylidenepropane-1,3-diamine palladium(II (2b, N,N′-bis(3,5-di-tert-butylsalicylidenepropane-1,3-diamine palladium(II (2c, and N,N′-bis(4-methoxy-salicylidenepropane-1,3-diamine palladium(II (2d, have been successfully synthesised and characterised by CHN elemental analyses and conventional spectroscopic methods. These complexes were investigated as catalysts in the phosphine-free Mizoroki-Heck cross-coupling reactions of aryl bromides with methyl acrylate.

Copper-based electrochemical sensor with palladium electrode for cathodic stripping voltammetry of manganese.

Science.gov (United States)

Kang, Wenjing; Pei, Xing; Bange, Adam; Haynes, Erin N; Heineman, William R; Papautsky, Ian

2014-12-16

In this work, we report on the development of a palladium-based, microfabricated point-of-care electrochemical sensor for the determination of manganese using square wave cathodic stripping voltammetry. Heavy metals require careful monitoring, yet current methods are too complex for a point-of-care system. Voltammetry offers an attractive approach to metal detection on the microscale, but traditional carbon, gold, or platinum electrodes are difficult or expensive to microfabricate, preventing widespread use. Our sensor uses palladium working and auxiliary electrodes and integrates them with a copper-based reference electrode for simple fabrication and compatibility with microfabrication and printed circuit board processing, while maintaining competitive performance in electrochemical detection. Copper electrodes were prepared on glass substrate using a combination of microfabrication procedures followed by electrodeposition of palladium. The disposable sensor system was formed by bonding a poly(dimethylsiloxane) (PDMS) well to the glass substrate. Cathodic stripping voltammetry of manganese using our new disposable palladium-based sensors exhibited 334 nM (18.3 ppb) limit of detection in borate buffer. The sensor was used to demonstrate manganese determination in natural water samples from a pond in Burnet Woods, located in Cincinnati, OH, and the Ohio River.

Green synthesis of palladium nanoparticles with carboxymethyl cellulose for degradation of azo-dyes

Energy Technology Data Exchange (ETDEWEB)

Li, Gang; Li, Yun; Wang, Zhengdong; Liu, Huihong, E-mail: huihongliu@126.com

2017-02-01

Palladium nanoparticles (PdNPs) were synthesized through friendly environmental method using PdCl{sub 2} and carboxymethyl cellulose (CMC) in an aqueous solution (pH 6) at controlled water bath (80 °C) for 30 min. CMC functioned as both reducing and stabilizing agent. The characterization through high resolution-transmission electron microscopic (HRTEM) and X-ray Fluorescence Spectrometry (XRF) inferred that the as-synthesized PdNPs were spherical in shape with a face cubic crystal (FCC) structure. The results from dynamic light scattering (DLS) suggested the PdNPs had the narrow size distribution with an average size of 2.5 nm. The negative zeta potential (−52.6 mV) kept the as-synthesized PdNPs stable more than one year. The PdNPs showed the excellent catalytic activity by reducing degradation of azo-dyes, such as p-Aminoazobenzene, acid red 66, acid orange 7, scarlet 3G and reactive yellow 179, in the present of sodium borohydride. - Highlights: • Green synthesis of palladium nanoparticles using carboxymethyl cellulose. • The synthesis of palladium nanoparticles were performed easily. • Carboxymethyl cellulose acts as both reducing and stabilization agents. • The as-synthesized palladium nanoparticles show excellent catalytic activity.

Vanadium alloy membranes for high hydrogen permeability and suppressed hydrogen embrittlement

International Nuclear Information System (INIS)

Kim, Kwang Hee; Park, Hyeon Cheol; Lee, Jaeho; Cho, Eunseog; Lee, Sang Mock

2013-01-01

The structural properties and hydrogen permeation characteristics of ternary vanadium–iron–aluminum (V–Fe–Al) alloy were investigated. To achieve not only high hydrogen permeability but also strong resistance to hydrogen embrittlement, the alloy composition was modulated to show high hydrogen diffusivity but reduced hydrogen solubility. We demonstrated that matching the lattice constant to the value of pure V by co-alloying lattice-contracting and lattice-expanding elements was quite effective in maintaining high hydrogen diffusivity of pure V

Study on the determination of palladium in biological samples by the method of neutron activation analysis

International Nuclear Information System (INIS)

Cavalcante, Cassio Queiroz

2007-01-01

Palladium is one of platinum group elements present in the nature at very low concentrations. However with the use of this element in the automobile catalyzers Pd became a new pollutant. Besides, Pd has been studied in the preparation of new antitumour drugs. Consequently, there is a need to determine Pd concentrations in biological and environmental samples. This study presents palladium results obtained in the analysis of biological samples and reference materials using instrumental thermal and epithermal neutron activation analysis (INAA and ENAA). The solvent extraction and solid phase extraction separation methods were also applied before ENAA. The samples analyzed in this study were, reference material BCR 723 - Palladium, Platinum and Rhodium in road dust, CCQM-P63 automotive catalyst material of the Proficiency Test and bovine tissue samples containing palladium prepared in the laboratory. Samples and palladium synthetic standard were irradiated at the IEA-R1 nuclear research reactor under thermal neutron flux of about 4 x 10 12 n cm-2 s-1, during a period of 4 and 16 h for INAA and ENAA, respectively. The induced gamma activity of 109 Pd to the sample and standard was measured using a hyper pure Ge detector coupled to a gamma ray spectrometer. The palladium concentration was calculated by comparative method. The gamma ray energy of 109 Pd radioisotope measured was of 88.0 keV, located in a spectrum region of low energy where occurs the interference of X rays, 'Bremsstrahlung' radiations, as well as Compton effect of 24 Na. The pre-separation of palladium from interfering elements by solvent extraction was performed using dimethylglyoxime complexant and chloroform as diluent. In the case of the pre separation procedure using solid reversed phase column, the palladium was retained using N,N-diethyl-N'-benzoyl thiourea complexant and eluted using ethanol. Aliquots of the resulting solutions from the pre-separations, free of interfering elements, were

Sulphur containing novel extractants for extraction-separation of palladium (II)

International Nuclear Information System (INIS)

Shukla, J.P.; Sawant, S.R.; Anil Kumar; Singh, R.K.

1995-01-01

Extraction performance of palladium (II) by sulphur containing extragents has unequivocally established their strong extraction ability toward this thiophilic soft metal. Hence a comprehensive investigative study was initiated by us to examine selective reversible extraction-separation of trace and macro amounts of palladium (II) from both aqueous nitric acid as well as hydrochloric acid media into 1,2-dichloroethane by 1,10-dithia-18 crown-6 (1,10-DT18C6), S 6 -pentano-36 (S 6 -P-36) and bis (2-ethylhexyl) sulphoxide (BESO) dissolved in toluene. From the study of aqueous phase acidity, reagent concentration, period of equilibration, diluent, strippant and diverse ions, conditions are established from its quantitative and reversible extraction. Recovery of Pd(II) from loaded thiacrown and sulphoxide phase is easily accomplished by using sodium thiocyanate, ammonium thiocyanate, thiourea, sodium thiosulphate and mixture of (2M Na 2 CO 3 + 0.5 NH 4 OH) (only for BESO) as the strippants. The lack of interference from even appreciable amounts of contaminants like 137 Cs, 106 Ru, 233 U and 239 Pu may be considered as one of the outstanding advantages of the method. Application of these extractants has been successfully tested for the recovery of palladium from high active waste matrix. The extracted complex from both the thiacrowns has been characterized by elemental analyses and UV-Visible spectra, confirmed to be PdA 2 .T (A = NO - 3 , Cl - ) from dilute (pH ∼ 2) acid solutions while composition of organic species with palladium for the sulphoxide, has also been confirmed to be disolvate of the type Pd(NO 3 ) 2 .2BESO. (author). 52 refs., 6 tabs., 6 figs

Investigation of high temperature reactions on solid substrates with Rutherford backscattering spectrometry: interaction of palladium with selenium on heated graphite surfaces

International Nuclear Information System (INIS)

Majidi, V.; Robertson, J.D.

1991-01-01

Selenium and palladium interactions on heated pyrolytically coated graphite substrates were investigated using Rutherford backscattering spectrometry. The studies were performed using selenium alone, palladium alone, and a combination of selenium and palladium deposited on the graphite substrates. The results indicate that palladium instantaneously stabilizes selenium at ambient temperatures and prevents the diffusion of selenium into the graphite. As the substrate is heated, temperature dependent diffusion of all analytes into the graphite is observed. Furthermore, it appears that the stabilization of selenium is due to the formation of a stoichiometric compound with palladium and oxygen. This compound decomposes at a temperature between 1070 and 1770 K. (author)

Investigation of high temperature reactions on solid substrates with Rutherford backscattering spectrometry: interaction of palladium with selenium on heated graphite surfaces

Energy Technology Data Exchange (ETDEWEB)

Majidi, V.; Robertson, J.D. (Kentucky Univ., Lexington, KY (United States). Dept. of Chemistry)

1991-01-01

Selenium and palladium interactions on heated pyrolytically coated graphite substrates were investigated using Rutherford backscattering spectrometry. The studies were performed using selenium alone, palladium alone, and a combination of selenium and palladium deposited on the graphite substrates. The results indicate that palladium instantaneously stabilizes selenium at ambient temperatures and prevents the diffusion of selenium into the graphite. As the substrate is heated, temperature dependent diffusion of all analytes into the graphite is observed. Furthermore, it appears that the stabilization of selenium is due to the formation of a stoichiometric compound with palladium and oxygen. This compound decomposes at a temperature between 1070 and 1770 K. (author).

In vitro permeation of palladium powders through intact and damaged human skin.

Science.gov (United States)

Crosera, Matteo; Mauro, Marcella; Bovenzi, Massimo; Adami, Gianpiero; Baracchini, Elena; Maina, Giovanni; Larese Filon, Francesca

2018-05-01

The use of palladium (Pd) has grown in the last decades, commonly used in automotive catalytic converters, jewellery and dental restorations sectors. Both general and working population can be exposed to this metal, which may act as skin sensitizer. This study investigated in vitro palladium powders permeation through excised intact and damaged human skin using the Franz diffusion cell method and the effect of rapid skin decontamination using sodium laureth-sulphate. 1 mL of a 10 min sonicated suspension made of 2.5 g of Pd powder in 50 mL synthetic sweat at pH 4.5 and room temperature was applied to the outer surface of the skin membranes for 24 h. Pd permeation, assessed by ICP-MS, was higher when damaged skin was used (p = 0.03). Final flux permeation values and lag times were 0.02 ± 0.01 μg cm -2  h -1 and 6.00 ± 3.95 h for intact, and 0.10 ± 0.02 μg cm -2  h -1 and 2.05 ± 1.49 h for damaged skin samples, respectively. Damaged skin protocol enhances Pd skin penetration inside dermal layer (p = 0.04), thus making the metal available for systemic uptake. Pd penetration (p = 0.02) and permeation (p = 0.012) through intact skin decreased significantly when a cleaning procedure was applied. This study demonstrates that after skin exposure to Pd powders a small permeation of the metal happen both through intact and damaged skin and that an early decontamination with a common cleanser can significantly decrease the final amount of metal available forsystemic uptake. Copyright © 2018 Elsevier B.V. All rights reserved.

Influence of hydrogen on the thermoelectric power of palladium alloyed with neighbouring elements: I. Pd/Ru/H and Pd/Rh/H alloys

CERN Document Server

Szafranski, A W

2003-01-01

Pd/Ru and Pd/Rh alloys have been loaded with hydrogen in high-pressure conditions. The resulting hydrogen contents were close to the stoichiometric composition, H/(Pd + Me) = 1. Lower hydrogen contents have been obtained by successive partial desorptions. The thermoelectric power and electrical resistance of one- and two-phase alloys have been measured simultaneously in the temperature range between 80 and 300 K. A Nordheim-Gorter type correlation of the two quantities has been observed in many cases and the partial thermopowers corresponding to electron-phonon scattering and lattice disorder could be determined. The observed anomalous behaviour of the total and partial thermopowers is attributed to virtual bound states of ruthenium or rhodium.

Chiral separation of substituted phenylalanine analogues using chiral palladium phosphine complexes with enantioselective liquid-liquid extraction

NARCIS (Netherlands)

Verkuijl, B.J.V.; Schuur, B.; Minnaard, A.J.; Vries, de J.G.; Feringa, B.L.

2010-01-01

Chiral palladium phosphine complexes have been employed in the chiral separation of amino acids and phenylalanine analogues in particular. The use of (S)-xylyl-BINAP as a ligand for the palladium complex in enantioselective liquid–liquid extraction allowed the separation of the phenylalanine

Development of PVDF Membrane Nanocomposites via Various Functionalization Approaches for Environmental Applications

Directory of Open Access Journals (Sweden)

Douglas M. Davenport

2016-01-01

Full Text Available Membranes are finding wide applications in various fields spanning biological, water, and energy areas. Synthesis of membranes to provide tunable flux, metal sorption, and catalysis has been done through pore functionalization of microfiltration (MF type membranes with responsive behavior. This methodology provides an opportunity to improve synthetic membrane performance via polymer fabrication and surface modification. By optimizing the polymer coagulation conditions in phase inversion fabrication, spongy polyvinylidene fluoride (PVDF membranes with high porosity and large internal pore volume were created in lab and full scale. This robust membrane shows a promising mechanical strength as well as high capacity for loading of adsorptive and catalytic materials. By applying surface modification techniques, synthetic membranes with different functionality (carboxyl, amine, and nanoparticle-based were obtained. These functionalities provide an opportunity to fine-tune the membrane surface properties such as charge and reactivity. The incorporation of stimuli-responsive acrylic polymers (polyacrylic acid or sodium polyacrylate in membrane pores also results in tunable pore size and ion-exchange capacity. This provides the added benefits of adjustable membrane permeability and metal capture efficiency. The equilibrium and dynamic binding capacity of these functionalized spongy membranes were studied via calcium ion-exchange. Iron/palladium catalytic nanoparticles were immobilized in the polymer matrix in order to perform the challenging degradation of the environmental pollutant trichloroethylene (TCE.

Hydrogenation of carbon monoxide over supported palladium catalysts

Energy Technology Data Exchange (ETDEWEB)

Fujimoto, K.; Hashimoto, H.; Kunugi, T.

1978-03-01

An alumina-supported 2% palladium catalyst had higher activity for carbon monoxide hydrogenation than a silica-supported 2% palladium catalyst, at 250/sup 0/-400/sup 0/C and 1 atm. The addition of lanthanum oxide or thorium oxide, but not of potassium oxide, to the silica-supported catalyst increased the conversion at 350/sup 0/C from 1.1% to 81.0% with a selectivity of 56.1% for methane, 1.4% for C/sub 2/ compounds, 0.1% for C/sub 3/ compounds, and 42.5% for carbon dioxide. Temperature-programed desorption of carbon monoxide in a hydrogen stream showed that of two desorption peaks observed for carbon monoxide, the one at higher temperature corresponded to the carbon monoxide species which hydrogenates to methane and that the area of this peak increased with increasing thorium content of the catalyst. Graphs, tables, and 12 references.

Determination of palladium by flame photometry; Determinacion de paladio por fotometria de llama

Energy Technology Data Exchange (ETDEWEB)

Parallada Bellod, R

1964-07-01

A study on the determination of palladium by lame photometry, fixing the most convent experimental conditions and using solvents to increase the emission of this elements is carried out. Among the organic solvents, acetone has been found the most efficient. The interferences produced by anions and cations have also been studied and an analytical method is related, in which lines of calibration of 0 to 100 ppm palladium re used. (Author) 7 refs.

Optical properties of palladium nanoparticles under exposure of hydrogen and inert gas prepared by dewetting synthesis of thin-sputtered layers

Energy Technology Data Exchange (ETDEWEB)

Kracker, Michael, E-mail: Michael.Kracker@uni-jena.de; Worsch, Christian; Ruessel, Christian [Otto-Schott-Institut, Jena University (Germany)

2013-04-15

Thin layers of palladium with a thickness of 5 nm were sputtered on fused silica substrates. Subsequently, the coated glasses were annealed at a temperature of 900 Degree-Sign C for 1 h. This resulted in the formation of small and well-separated palladium nanoparticles with diameters in the range from 20 to 200 nm on the glass surface. The existence of a palladium oxide layer can be detected using optical absorption spectroscopy. Purging with hydrogen leads to an irreversible change in the optical spectra due to the reduction of PdO to metallic palladium. Changing the gas atmosphere from hydrogen to argon leads to significant reversible changes in the optical properties of the particle layer. Based on Mie theory and the respective dielectric functions, the spectra were calculated using the real particle size distribution, weighted dispersions relation to adapt the geometrical conditions and complex dielectric functions of palladium and palladium hydride. A good agreement with measured spectra was found and the dependency of the surrounding media can be explained.Graphical Abstract.

Palladium on Carbon-Catalyzed Suzuki-Miyaura Coupling Reaction Using an Efficient and Continuous Flow System

Directory of Open Access Journals (Sweden)

Tomohiro Hattori

2015-01-01

Full Text Available The continuous flow Suzuki-Miyaura reaction between various haloarenes and arylboronic acids was successfully achieved within only ca. 20 s during the single-pass through a cartridge filled with palladium on carbon (Pd/C. No palladium leaching was observed in the collected reaction solution by atomic absorption spectrometry (detection limit: 1 ppm.

Behavior of palladium and its impact on intermetallic growth in palladium-coated Cu wire bonding

International Nuclear Information System (INIS)

Xu Hui; Qin, Ivy; Clauberg, Horst; Chylak, Bob; Acoff, Viola L.

2013-01-01

This paper describes the behavior of palladium in palladium-coated Cu (PdCu) wire bonding and its impact on bond reliability by utilizing transmission electron microscopy (TEM). A Pd layer approximately 80 nm thick, which is coated on the surface of Cu wire, dissolves into the Cu matrix during ball formation (under N 2 gas protection) when the wire tip is melted to form a ball. As a result of dissolving the very thin Pd layer into the ball, Pd is almost undetectable along the entire bond interface between the ball and the Al pad. The behavior of Pd during thermal aging in air, however, is different for central and peripheral interfaces. At the central interface, less than 5 at.% Pd is present after 168 h aging at 175 °C. At the periphery, however, Pd diffuses back and congregates, reaching a level of ∼12 at.% after 24 h, and a Pd-rich (Cu,Pd) 9 Al 4 layer (>40 at.% Pd) forms after 168 h. Pd acts substitutionally in Cu 9 Al 4 but cannot penetrate into the CuAl 2 or CuAl. By comparison of intermetallic thickness and interfacial morphology between PdCu and bare Cu wire bonds, it is concluded that the presence of Pd reduces intermetallic growth rate, and is associated with numerous nanovoids in PdCu bonds.

Tritium evolution from various morphologies of palladium

International Nuclear Information System (INIS)

Tuggle, D.G.; Claytor, T.N.; Taylor, S.F.

1994-01-01

The authors have been able to extend the tritium production techniques to various novel morphologies of palladium. These include small solid wires of various diameters and a type of pressed powder wire and a plasma cell. In most successful experiments, the amount of palladium required, for an equivalent tritium output, has been reduced by a factor of 100 over the older powder methods. In addition, they have observed rates of tritium production (>5 nCi/h) that far exceed most of the previous results. Unfortunately, the methods that they currently use to obtain the tritium are poorly understood and consequently there are numerous variables that need to be investigated before the new methods are as reliable and repeatable as the previous techniques. For instance, it seems that surface and/or bulk impurities play a major role in the successful generation of any tritium. In those samples with total impurity concentrations of >400 ppM essentially no tritium has been generated by the gas loading and electrical simulation methods

Study on the poisoning resistance of Pd-coated ZrCo alloy prepared by electroless plating method

Energy Technology Data Exchange (ETDEWEB)

Guo, Xiumei, E-mail: xiumei418@163.com; Wang, Shumao; Li, Zhinian; Yuan, Baolong; Ye, Jianhua; Qiu, Haochen; Wu, Yuanfang; Liu, Xiaopeng; Jiang, Lijun

2016-12-15

Highlights: • The Pd membrane was prepared by electroless plating method. • The Pd membrane was compact and uniform. • The effectiveness of Pd membranes was affected by impurity contents and temperatures. - Abstract: To improve the poisoning resistance of ZrCo alloy, Pd membranes have been prepared over the surface of the alloy substrates by using electroless plating method. The characteristics of Pd membranes have been examined by XRD, SEM, EDS and EPMA technologies. From SEM images, the uniform and compact thin Pd film was revealed. The effect of this Pd film was evaluated by comparing the hydrogen absorption properties of bare and Pd-coated ZrCo specimens in contaminated hydrogen gas. The degradation of hydrogen absorption of Pd-coated ZrCo induced by poisoning was less than that of bare ZrCo sample obviously, meaning that the Pd membranes over the surface of substrates appeared to be effective in improving the poisoning resistance of ZrCo alloy. Furthermore, the effect became more significant with the increasing of impurity contents in the experimental gas and the operation temperatures.

Palladium-catalyzed allylation of tautomerizable heterocycles with alkynes.

Science.gov (United States)

Lu, Chuan-Jun; Chen, Dong-Kai; Chen, Hong; Wang, Hong; Jin, Hongwei; Huang, Xifu; Gao, Jianrong

2017-07-21

A method for the allylic amidation of tautomerizable heterocycles was developed by a palladium catalyzed allylation reaction with 100% atom economy. A series of structurally diverse N-allylic substituted heterocycles can be synthesized in good yields with high chemo-, regio-, and stereoselectivities under mild conditions.

Fractal analysis of electrolytically-deposited palladium hydride dendrites

International Nuclear Information System (INIS)

Bursill, L.A.; Julin, Peng; Xudong, Fan.

1990-01-01

The fractal scaling characteristics of the surface profile of electrolytically-deposited palladium hydride dendritic structures have been obtained using conventional and high resolution transmission electron microscopy. The results are in remarkable agreement with the modified diffusion-limited aggregation model. 19 refs., 3 tabs., 13 figs

Antibacterial properties of palladium nanostructures sputtered on polyethylene naphthalate

Czech Academy of Sciences Publication Activity Database

Polívková, M.; Válová, M.; Siegel, J.; Rimpelová, S.; Hubáček, Tomáš; Lyutakov, O.; Švorčík, V.

2015-01-01

Roč. 5, č. 90 (2015), s. 73767-73774 ISSN 2046-2069 Institutional support: RVO:60077344 Keywords : polymer * palladium sputtering * annealing * nanostructure * antibacterial effect Subject RIV: JJ - Other Materials Impact factor: 3.289, year: 2015

QuadraPure-Supported Palladium Nanocatalysts for Microwave-Promoted Suzuki Cross-Coupling Reaction under Aerobic Condition

Directory of Open Access Journals (Sweden)

Kin Hong Liew

2014-01-01

Full Text Available Cross-linked resin-captured palladium (XL-QPPd was readily prepared by simple physical adsorption onto the high loading QuadraPure macroporous resin and a subsequent reduction process. To enhance the mechanical stability, entrapped palladium nanocatalysts were cross-linked with succinyl chloride. Both transmission electron microscopy images and X-ray diffraction analysis revealed that the palladium nanoparticles were well dispersed with diameters ranging in 4–10 nm. The catalyst performed good catalytic activity in microwave-promoted Suzuki cross-coupling reactions in water under aerobic condition with mild condition by using various aryl halides and phenylboronic acid. In addition, the catalyst showed an excellent recyclability without significant loss of catalytic activity.

Structural Characterizations of Palladium Clusters Prepared by Polyol Reduction of [PdCl4]2− Ions

Directory of Open Access Journals (Sweden)

Loredana Schiavo

2016-01-01

Full Text Available Palladium nanoparticles are of great interest in many industrial fields, ranging from catalysis and hydrogen technology to microelectronics, thanks to their unique physical and chemical properties. In this work, palladium clusters have been prepared by reduction of [PdCl4]2− ions with ethylene glycol, in the presence of poly(N-vinyl-2-pyrrolidone (PVP as stabilizer. The stabilizer performs the important role of nucleating agent for the Pd atoms with a fast phase separation, since palladium atoms coordinated to the polymer side-groups are forced at short distances during nucleation. Quasispherical palladium clusters with a diameter of ca. 2.6 nm were obtained by reaction in air at 90°C for 2 hours. An extensive materials characterization by transmission electron microscopy (TEM, X-ray diffraction (XRD, X-ray photoelectron spectroscopy (XPS, and other characterizations (TGA, SEM, EDS-SEM, and UV-Vis has been performed in order to evaluate the structure and oxidation state of nanopalladium.

Interfacial microstructure and shear strength of reactive air brazed oxygen transport membrane ceramic-metal alloy joints

Science.gov (United States)

FR, Wahid Muhamad; Yoon, Dang-Hyok; Raju, Kati; Kim, Seyoung; Song, Kwang-sup; Yu, Ji Haeng

2018-01-01

To fabricate a multi-layered structure for maximizing oxygen production, oxygen transport membrane (OTM) ceramics need to be joined or sealed hermetically metal supports for interfacing with the peripheral components of the system. Therefore, in this study, Ag-10 wt% CuO was evaluated as an effective filler material for the reactive air brazing of dense Ce0.9Gd0.1O2-δ-La0.7Sr0.3MnO3±δ (GDC-LSM) OTM ceramics. Thermal decomposition in air and wetting behavior of the braze filler was performed. Reactive air brazing was performed at 1050 °C for 30 min in air to join GDC-LSM with four different commercially available high temperature-resistant metal alloys, such as Crofer 22 APU, Inconel 600, Fecralloy, and AISI 310S. The microstructure and elemental distribution of the ceramic-ceramic and ceramic-metal interfaces were examined from polished cross-sections. The mechanical shear strength at room temperature for the as-brazed and isothermally aged (800 °C for 24 h) joints of all the samples was compared. The results showed that the strength of the ceramic-ceramic joints was decreased marginally by aging; however, in the case of metal-ceramic joints, different decreases in strengths were observed according to the metal alloy used, which was explained based on the formation of different oxide layers at the interfaces.

Neutron activation determination of gold and palladium using extraction by organic sulfides

International Nuclear Information System (INIS)

Gil'berg, Eh.N.; Torgov, V.G.; Verevkin, G.V.; AN SSSR, Novosibirsk. Inst. Neorganicheskoj Khimii)

1978-01-01

Compared are methods of gold determination in standard rock samples of the USA National Geological Service: a) extraction by solutions of dioctylsulfide and oil sulfides from irradiated samples; b) preliminary extraction by the above solfides with the following extract radiation; c) the method of isotope dilution with substoichiometry extraction. A possibility is studied to determine palladium in the sulfide extract with gold using the NaI(Tl) thin crystal scintillators. It is established that joint palladium and gold extraction permits to determine them in many natural products simultaneously

Palladium-catalysed arylation of acetoacetate esters to yield 2-arylacetic acid esters

CSIR Research Space (South Africa)

Zeevaart, JG

2004-05-24

Full Text Available , was developed simultaneously by Hart- wig and Buchwald.5 Typically the tert-butyl ester of propionic acid is treated with an aryl halide (bromide or chloride) in the presence of a strong base, palladium and a bulky phosphine ligand or a bulky imidazolinium CO2t... novel palladium- catalysed conditions for the arylation of acetoacetate esters resulting in the formation of 2-arylacetic acid esters. When we attempted the arylation of tert-butyl aceto- acetate 1a with bromobenzene 2a using mild reaction conditions (K3...

Exposure to nickel and palladium from dental appliances

NARCIS (Netherlands)

Ventura Da Cruz Rodrigues Milheiro, A.M.

2015-01-01

The application of a dental material into the oral cavity is not free of biological implications, as deterioration of the material will undoubtedly occur. The adverse health effects of palladium and nickel are well known and their immunologic cross-reactivity is well established. The aim of this

Study of electroplated silver-palladium biofouling inhibiting coating

DEFF Research Database (Denmark)

Chiang, Wen-Chi; Hilbert, Lisbeth Rischel; Schroll, Casper

2008-01-01

Biofouling can cause many undesirable effects in industrial and medical settings. In this study, a new biofouling inhibiting Ag-Pd surface was designed to form an inhibiting effect by itself. This design was based on silver combined with nobler palladium, both with catalytic properties. Owing to ...

Density functional theory metadynamics of silver, caesium and palladium diffusion at β-SiC grain boundaries

Energy Technology Data Exchange (ETDEWEB)

Rabone, Jeremy, E-mail: jeremy.rabone@ec.europa.eu [European Commission, Joint Research Centre, Institute for Transuranium Elements, D-76125 Karlsruhe (Germany); López-Honorato, Eddie [Centro de Investigación y de Estudios Avanzados del IPN (CINVESTAV), Unidad Saltillo, Industria Metalúrgica 1062, Parque Industrial, Ramos Arizpe 25900, Coahuila (Mexico)

2015-03-15

Highlights: • DFT metadynamics of diffusion of Pd, Ag and Cs on grain boundaries in β-SiC. • The calculated diffusion rates for Pd and Ag tally with experimental release rates. • A mechanism of release other than grain boundary diffusion seems likely for Cs. - Abstract: The use of silicon carbide in coated nuclear fuel particles relies on this materials impermeability towards fission products under normal operating conditions. Determining the underlying factors that control the rate at which radionuclides such as Silver-110m and Caesium-137 can cross the silicon carbide barrier layers, and at which fission products such as palladium could compromise or otherwise alter the nature of this layer, are of paramount importance for the safety of this fuel. To this end, DFT-based metadynamics simulations are applied to the atomic diffusion of silver, caesium and palladium along a Σ5 grain boundary and to palladium along a carbon-rich Σ3 grain boundary in cubic silicon carbide at 1500 K. For silver, the calculated diffusion coefficients lie in a similar range (7.04 × 10{sup −19}–3.69 × 10{sup −17} m{sup 2} s{sup −1}) as determined experimentally. For caesium, the calculated diffusion rates are very much slower (3.91 × 10{sup −23}–2.15 × 10{sup −21} m{sup 2} s{sup −1}) than found experimentally, suggesting a different mechanism to the simulation. Conversely, the calculated atomic diffusion of palladium is very much faster (7.96 × 10{sup −11}–7.26 × 10{sup −9} m{sup 2} s{sup −1}) than the observed penetration rate of palladium nodules. This points to the slow dissolution and rapid regrowth of palladium nodules as a possible ingress mechanism in addition to the previously suggested migration of entire nodules along grain boundaries. The diffusion rate of palladium along the Σ3 grain boundary was calculated to be slightly slower (2.38 × 10{sup −11}–8.24 × 10{sup −10} m{sup 2} s{sup −1}) than along the Σ5 grain boundary. Rather

Recent advances in liquid membranes and their applications in nuclear waste processing: an overview

Energy Technology Data Exchange (ETDEWEB)

Shukla, J P; Iyer, R H [Radiochemistry Division, Bhabha Atomic Research Centre, Mumbai (India)

1994-06-01

Membrane extraction, combining the processes of extraction, scrubbing and stripping in a single step, demonstrates the inherent capability of solvent extraction under non-equilibrium conditions. Permeant transport across various liquid membrane (LM) configurations, viz. bulk liquid, emulsion liquid and supported liquid membranes has great potential for applications in the nuclear field particularly in the decontamination of low and medium level radioactive wastes. Potential practical applications of such membranes have also been envisaged in the recovery of metals from hydrometallurgical leach solutions and in plutonium and americium removal from nitric acid waste streams generated by plutonium recovery operations in the PUREX process. Studies carried out have established that minor actinides like uranium, plutonium and americium from process effluents can easily be transported across polymeric and liquid type membranes through the use of specific ionophores dissolved in an appropriate liquid membrane phase. The possibility of the membrane extraction of fission palladium from acidic wastes has also been demonstrated by the use of some soft bases. An overview of these results and also some of the recent radiochemical applications of energy - efficient LM processes including directions for future research are outlined in this paper. (author). 19 refs., 1 fig., 2 tabs.

Watermelon rind-mediated green synthesis of noble palladium nanoparticles: catalytic application

Science.gov (United States)

Lakshmipathy, R.; Palakshi Reddy, B.; Sarada, N. C.; Chidambaram, K.; Khadeer Pasha, Sk.

2015-02-01

The present study reports the feasibility of synthesis of palladium nanoparticles (Pd NPs) by watermelon rind. The aqueous extract prepared from watermelon rind, an agro waste, was evaluated as capping and reducing agent for biosynthesis of palladium nanoparticles. The formation of Pd NPs was visually monitored with change in color from pale yellow to dark brown and later monitored with UV-Vis spectroscopy. The synthesized Pd NPs were further characterized by XRD, FTIR, DLS, AFM and TEM techniques. The synthesized Pd NPs were employed in Suzuki coupling reaction as catalyst. The results reveal that watermelon rind, an agro waste, is capable of synthesizing spherical-shaped Pd NPs with catalytic activity.

Insertion of molecular oxygen into a palladium(II) methyl bond: a radical chain mechanism involving palladium(III) intermediates.

Science.gov (United States)

Boisvert, Luc; Denney, Melanie C; Hanson, Susan Kloek; Goldberg, Karen I

2009-11-04

The reaction of (bipy)PdMe(2) (1) (bipy = 2,2'-bipyridine) with molecular oxygen results in the formation of the palladium(II) methylperoxide complex (bipy)PdMe(OOMe) (2). The identity of the product 2 has been confirmed by independent synthesis. Results of kinetic studies of this unprecedented oxygen insertion reaction into a palladium alkyl bond support the involvement of a radical chain mechanism. Reproducible rates, attained in the presence of the radical initiator 2,2'-azobis(2-methylpropionitrile) (AIBN), reveal that the reaction is overall first-order (one-half-order in both [1] and [AIBN], and zero-order in [O(2)]). The unusual rate law (half-order in [1]) implies that the reaction proceeds by a mechanism that differs significantly from those for organic autoxidations and for the recently reported examples of insertion of O(2) into Pd(II) hydride bonds. The mechanism for the autoxidation of 1 is more closely related to that found for the autoxidation of main group and early transition metal alkyl complexes. Notably, the chain propagation is proposed to proceed via a stepwise associative homolytic substitution at the Pd center of 1 with formation of a pentacoordinate Pd(III) intermediate.

Flexible palladium-based H2 sensor with fast response and low leakage detection by nanoimprint lithography.

Science.gov (United States)

Lim, Su Hui; Radha, Boya; Chan, Jie Yong; Saifullah, Mohammad S M; Kulkarni, Giridhar U; Ho, Ghim Wei

2013-08-14

Flexible palladium-based H2 sensors have a great potential in advanced sensing applications, as they offer advantages such as light weight, space conservation, and mechanical durability. Despite these advantages, the paucity of such sensors is due to the fact that they are difficult to fabricate while maintaining excellent sensing performance. Here, we demonstrate, using direct nanoimprint lithography of palladium, the fabrication of a flexible, durable, and fast responsive H2 sensor that is capable of detecting H2 gas concentration as low as 50 ppm. High resolution and high throughput patterning of palladium gratings over a 2 cm × 1 cm area on a rigid substrate was achieved by heat-treating nanoimprinted palladium benzyl mercaptide at 250 °C for 1 h. The flexible and robust H2 sensing device was fabricated by subsequent transfer nanoimprinting of these gratings into a polycarbonate film at its glass transition temperature. This technique produces flexible H2 sensors with improved durability, sensitivity, and response time in comparison to palladium thin films. At ambient pressure and temperature, the device showed a fast response time of 18 s at a H2 concentration of 3500 ppm. At 50 ppm concentration, the response time was found to be 57 s. The flexibility of the sensor does not appear to compromise its performance.

Hydrogen uptake causes molecular "avalanches" in palladium | Argonne

Science.gov (United States)

air cylinders for storing the gas. Palladium, a precious metal closely related to platinum, is that storage or purification, and this research gets us closer to making that a reality. In this study take up hydrogen from the environment. "The ultimate goal is hydrogen storage or purification, and

Advanced Ultrasupercritical (AUSC) Tube Membrane Panel Development

Energy Technology Data Exchange (ETDEWEB)

Pschirer, James [Alstom Power Inc., Windsor, CT (United States); Burgess, Joshua [Alstom Power Inc., Windsor, CT (United States); Schrecengost, Robert [Alstom Power Inc., Windsor, CT (United States)

2017-08-16

Alstom Power Inc., a wholly owned subsidiary of the General Electric Company (GE), has completed the project “Advanced Ultrasupercritical (AUSC) Tube Membrane Panel Development” under U.S. Department of Energy (DOE) Award Number DE-FE0024076. This project was part of DOE’s Novel Crosscutting Research and Development to Support Advanced Energy Systems program. AUSC Tube Membrane Panel Development was a two and one half year project to develop and verify the manufacturability and serviceability of welded tube membrane panels made from high performance materials suitable for the AUSC steam cycles, defined as high pressure steam turbine inlet conditions of 700-760°C (1292-1400°F) and 24.5-35MPa (3500-5000psi). The difficulty of this challenge lies in the fact that the membrane-welded construction imposes demands on the materials that are unlike any that exist in other parts of the boiler. Tube membrane panels have been designed, fabricated, and installed in boilers for over 50 years with relatively favorable experience when fabricated from carbon and Cr-Mo low alloy steels. The AUSC steam cycle requires membrane tube panels fabricated from materials that have not been used in a weldment with metal temperatures in the range of 582-610°C (1080-1130°F). Fabrication materials chosen for the tubing were Grade 92 and HR6W. Grade 92 is a creep strength enhanced ferritic Cr-Mo alloy and HR6W is a high nickel alloy. Once the materials were chosen, GE performed the engineering design of the panels, prepared shop manufacturing drawings, and developed manufacturing and inspection plans. After the materials were purchased, GE manufactured and inspected the tube membrane panels, determined if post fabrication heat treatment of the tube membrane panels was needed, performed pre- and post-weld heat treatment on the Grade 92 panels, conducted final nondestructive inspection of any heat treated tube membrane panels, conducted destructive inspection of the completed tube

Adhesion enhancement between electroless nickel and polyester fabric by a palladium-free process

Energy Technology Data Exchange (ETDEWEB)

Lu Yinxiang, E-mail: yxlu@fudan.edu.cn [Department of Materials Science, Fudan University, 220 Handan Road, Shanghai 200433 (China); Xue Longlong; Li Feng [Department of Materials Science, Fudan University, 220 Handan Road, Shanghai 200433 (China)

2011-01-15

A new, efficient, palladium- and etchant-free process for the electroless nickel plating of poly(ethylene terephthalate) (PET) fabric has been developed. PET electroless plating can be prepared in three steps, namely: (i) the grafting of thiol group onto PET, (ii) the silver Ag{sup 0} seeding of the PET surface, and (iii) the nickel metallization using electroless plating bath. Scanning electron microscopy (SEM), energy dispersive X-ray (EDX) analysis, X-ray photoelectron spectroscopy (XPS), Raman spectrometer, X-ray diffraction (XRD), and thermogravimetric analysis (TG) were used to characterize the samples in the process, and the nickel loading was quantified by weighing. This process successfully compares with the traditional one based on KMnO{sub 4}/H{sub 2}SO{sub 4} etching and palladium-based seed layer. The nickel coating obtained in this palladium-free process can pass through ultrasonic washing challenge, and shows excellent adhesion with the PET substrate. However, the sample with Pd catalyst via traditional process was damaged during the testing experiment.

Co-deposition of palladium with hydrogen isotopes

International Nuclear Information System (INIS)

Dash, J.; Ambadkar, A.

2006-01-01

Palladium was co-deposited with hydrogen isotopes on a Pd cathode. This resulted in enhanced production of excess thermal power. After electrolysis the Pd Lβ/ Lα ratio was found to be increased in characteristic X-ray spectra from localized, microscopic areas on the surface of the Pd cathode. This suggests the possibility that appreciable amounts of silver are present in these areas. (authors)

Preparation of palladium nanoparticles on alumina surface by chemical co-precipitation method and catalytic applications

Energy Technology Data Exchange (ETDEWEB)

Kumar, Avvaru Praveen; Kumar, B. Prem; Kumar, A.B.V. Kiran; Huy, Bui The [Department of Chemistry, Changwon National University, Changwon 641-773 (Korea, Republic of); Lee, Yong-Ill, E-mail: yilee@changwon.ac.kr [Department of Chemistry, Changwon National University, Changwon 641-773 (Korea, Republic of)

2013-01-15

Highlights: Black-Right-Pointing-Pointer Facile synthesis of palladium nanoparticles on alumina surface. Black-Right-Pointing-Pointer The surface morphology and properties of the nanocrystalline powders were characterized. Black-Right-Pointing-Pointer The catalytic activities of palladium nanoparticles were investigated. - Abstract: The present work reports a chemical co-precipitation process to synthesize palladium (Pd) nanoparticles using alumina as a supporting material. The optimized temperature for the formation of nanocrystalline palladium was found to be 600 Degree-Sign C. The X-ray diffraction (XRD) and Raman spectroscopy were used to study the chemical nature of the Pd in alumina matrix. The surface morphology and properties of the nanocrystalline powders were examined using thermogravimetric analysis (TG-DTA), XRD, Raman spectroscopy, transmission electron microscopy (TEM), scanning electron microscopy (SEM) and atomic force microscopy (AFM). The calcinations in different atmospheres including in the inert medium forms the pure nano Pd{sup 0} while in the atmospheric air indicates the existence pure Pd{sup 0} along with PdO nanoparticles. The catalytic activities of the as-synthesized nanocrystalline Pd nanoparticles in the alumina matrix were investigated in Suzuki coupling, Hiyama cross-coupling, alkene and alkyne hydrogenation, and aerobic oxidation reactions.

Influence of residual catalyst on the properties of conjugated polyphenylenevinylene materials: Palladium nanoparticles and poor electrical performance

DEFF Research Database (Denmark)

Krebs, Frederik C; Nyberg, R.B.; Jørgensen, M.

2004-01-01

polymer material prepared by two different routes: the palladium route and the condensation route. The performance in a device application of the two polymer materials was, however, very different, and the palladium route was demonstrated to give poor films with low breakdown voltages and short circuits....

Insights into functional-group-tolerant polymerization catalysis with phosphine-sulfonamide palladium (II) complexes

KAUST Repository

Jian, Zhongbao; Falivene, Laura; Wucher, Philipp; Roesle, Philipp; Caporaso, Lucia; Cavallo, Luigi; Gç ttker-Schnetmann, Inigo; Mecking, Stefan

2014-01-01

Two series of cationic palladium(II) methyl complexes {[(2-MeOC6H4)2PC6H4SO2NHC6H3(2,6-R1,R2)]PdMe}2[A]2 (X1+-A: R1=R2=H: H1+-A; R1=R2=CH(CH3)2: DIPP1+-A; R1=H, R2=CF3: CF31+-A; A=BF4 or SbF6) and neutral palladium(II) methyl complexes {[(2-MeOC6H4

Site preference of rare earth doping in palladium-iron-arsenide superconductors

Energy Technology Data Exchange (ETDEWEB)

Stuerzer, Christine; Schulz, Anne; Johrendt, Dirk [Department Chemie, Ludwig-Maximilians-Universitaet Muenchen (Germany)

2014-12-15

The solid solutions (Ca{sub 1-y}RE{sub y}Fe{sub 1-x}Pd{sub x}As){sub 10}Pd{sub z}As{sub 8} with RE = La, Ce, and Pr were synthesized by solid state methods and characterized by X-ray powder diffraction with subsequent Rietveld refinements [(CaFeAs){sub 10}Pt{sub 3}As{sub 8}-type structure (''1038 type''), P anti 1, Z = 1]. Substitution levels (Ca/RE, Fe/Pd, and Pd/□) obtained from Rietveld refinements coincide well with the nominal values according to EDS and the linear courses of the lattice parameters as expected from the ionic radii. The RE atoms favor the one out of five calcium sites, which is eightfold coordinated by arsenic. This leads to significant stabilization of the structure, and especially prevents palladium over-doping in the iron-arsenide layers as observed in the pristine compound (CaFe{sub 1-x}Pd{sub x}As){sub 10}Pd{sub z}As{sub 8}. While the stabilization energy is estimated to about 40 kJ.mol{sup -1} by electronic structure calculations, the reason for the diminished Fe/Pd substitution through RE doping is still not yet understood. We suggest that the electrons transferred from RE{sup 3+} to the (Fe{sub 1-x}Pd{sub x})As layer makes higher palladium concentrations unfavorable. Anyway the reduced palladium doping enables superconductivity with critical temperatures up to 20 K (onset) in the RE doped Pd1038 samples, which could not be obtained earlier due to palladium over-doping in the active iron-arsenide layers. (Copyright copyright 2014 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

REMOVAL OF NICKEL(II) AND PALLADIUM(II) FROM SURFACE ...

African Journals Online (AJOL)

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Nickel is widely used in electroplating, in the manufacture of Ni-Cd batteries, in rods for arc welding, in pigments for ... Palladium has an extensive use in electrical industry as grids for ... It is also used as catalytic converter in motor vehicles.

Palladium-based nanocatalysts for alcohol electrooxidation in alkaline media

CSIR Research Space (South Africa)

Modibedi, RM

2013-01-01

Full Text Available in the electrocatalytic oxidation of alcohols in alkaline media compared to platinum catalysts. Recent efforts have focused on the discovery of palladium-based electrocatalysts with little or no platinum for oxygen reduction reaction (ORR). This chapter is an overview...

Corrosion of Dental Au-Ag-Cu-Pd Alloys in 0.9 % Sodium Chloride Solution

International Nuclear Information System (INIS)

Chiba, Atsushi; Kusayanagi, Yukiharu

2005-01-01

Two Au-Ag-Cu-Pd dental casting alloys (Au:12% and 20%) used. The test solutions used 0.9 % NaCl solution (isotonic sodium chloride solution), 0.9 % NaCl solution containing 1 % lactic acid, and 0.9 % NaCl solution containing 1 % lactic acid and 0.1 mol dm -3 Na 2 S. The surface of two samples in three sample solutions was not natural discoloration during one year. The alloy containing 12 % gold was easily alloyed and the composition was uniform comparing with the alloy containing 20 % gold. The rest potentials have not a little effect after three months. The kinds of metals could not definitely from the oxidation and reduction waves of metal on the cyclic voltammograms. The dissolutions of gold and palladium were 12 % Au sample in the 0.9 % NaCl solution containing 1 % lactic acid and 0.1 mol dm -3 Na 2 S. The pH of solution had an affect on dissolution of copper, and sulfur ion had an affect on dissolution of silver. The copper dissolved amount from 20 % gold sample was about 26 times comparing with that of 12 % gold sample in the 0.9 % solution containing 1 % lactic acid. Corrosion products were silver chloride and copper chloride in NaCl solution, and silver sulfide and copper sulfide in NaCl solution containing Na 2 S

Microscopic observations of palladium used for cold fusion

International Nuclear Information System (INIS)

Matsumoto, T.

1991-01-01

This paper examines the microscopic structures of palladium metals used for cold fusion experiments. Tiny spot defects suggesting cold fusion have been observed in grain boundaries as the Nattoh model predicts. The relationship between these defects and a series of neutron busts and an indirect loop of hydrogen chain reactions are discussed

Palladium-catalyzed aryl C-H olefination with unactivated, aliphatic alkenes.

Science.gov (United States)

Deb, Arghya; Bag, Sukdev; Kancherla, Rajesh; Maiti, Debabrata

2014-10-01

Palladium-catalyzed coupling between aryl halides and alkenes (Mizoroki-Heck reaction) is one of the most popular reactions for synthesizing complex organic molecules. The limited availability, problematic synthesis, and higher cost of aryl halide precursors (or their equivalents) have encouraged exploration of direct olefination of aryl carbon-hydrogen (C-H) bonds (Fujiwara-Moritani reaction). Despite significant progress, the restricted substrate scope, in particular noncompliance of unactivated aliphatic olefins, has discouraged the use of this greener alternative. Overcoming this serious limitation, we report here a palladium-catalyzed chelation-assisted ortho C-H bond olefination of phenylacetic acid derivatives with unactivated, aliphatic alkenes in good to excellent yields with high regio- and stereoselectivities. The versatility of this operationally simple method has been demonstrated through drug diversification and sequential C-H olefination for synthesizing divinylbenzene derivatives.

Angle-resolved photoemission on the Kondo surface alloy CePd{sub 7}

Energy Technology Data Exchange (ETDEWEB)

Mulazzi, Mattia; Seibel, Christoph; Schwab, Holger [Universitaet Wuerzburg, Experimentelle Physik VII (Germany); Shimada, Kenya; Jiang, Jiang [Graduate School of Science, Hiroshima University, Higashi-Hiroshima (Japan); Reinert, Friedrich [Universitaet Wuerzburg, Experimentelle Physik VII (Germany); Karlsruhe Institute of Technology KIT, Gemeinschaftslabor fuer Nanoanalytik, Karlsruhe (Germany)

2013-07-01

This films of the Cerium were evaporated on a Pd(001) substrate an further annealed to obtain a thin surface alloy layer of stoichiometry CePd{sub 7}, as observed by Auger spectroscopy. From LEED measurements it was possible to determine that the alloy has a (√(5) x √(5))R26.6 {sup circle} reconstruction, commensurate to the Palladium substrate. Photon-energy dependent ARPES measurements crossing the 4d-4f resonance show the presence of a strong peak near the Fermi level, having actually two components, the actual Kondo peak at the Fermi level and the spin-orbit peak at 280 meV binding energy. Resonant and non-resonant Fermi surface maps shows large intensity variations of the Pd bands, when measured at the resonance, a sign of strong hybridization between the conduction and the 4f electrons. While previous work assigns the CePd7 to the class of intermediate valence systems, our work shows that it is actually a Kondo system, with a rather high Kondo temperature.

Progress in excess of power experiments with electrochemical loading of deuterium in palladium

International Nuclear Information System (INIS)

Violante, V.; Moretti, S.; Bertolotti, M.

2006-01-01

A research activity has been carried out, during the last 3 years, in the field of triggering anomalous heat effects in palladium deuteride. An enhancement of the excess of power reproducibility in deuterated palladium was obtained by using He-Ne Laser irradiation during electrochemical loading. A preliminary correlation between excess of energy and 4 He concentration increasing above the background was found. The continuation of the experimental program confirmed that Laser triggering produce an interesting gain of reproducibility. An upgrade of the experimental set-up has been realized. (author)

Palladium clusters deposited on the heterogeneous substrates

Energy Technology Data Exchange (ETDEWEB)

Wang, Kun, E-mail: cqdxwk@126.com [College of Power Engineering, Chongqing University, Chongqing 400044 (China); Key Laboratory of Low-grade Energy Utilization Technologies and Systems, Ministry of Education of PRC, Chongqing 400044 (China); Liu, Juanfang, E-mail: juanfang@cqu.edu.cn [College of Power Engineering, Chongqing University, Chongqing 400044 (China); Key Laboratory of Low-grade Energy Utilization Technologies and Systems, Ministry of Education of PRC, Chongqing 400044 (China); Chen, Qinghua, E-mail: qhchen@cqu.edu.cn [College of Power Engineering, Chongqing University, Chongqing 400044 (China); Key Laboratory of Low-grade Energy Utilization Technologies and Systems, Ministry of Education of PRC, Chongqing 400044 (China)

2016-07-15

Graphical abstract: The site-exchange between the substrate and cluster atoms can result in the formation of the surface alloys and the reconstruction of the cluster structure before the collision system approaching the thermal equilibrium. The deposited cluster adjusted the atom arrangement as possibly as to match the substrate lattice arrangement from bottom to up. The structural reconstruction is accompanied by the system potential energy minimization. - Highlights: • The deposition process can divide explicitly into three stages: adsorption, collision, relaxation. • The local melt does not emerge inside the substrate during the deposition process. • Surface alloys are formed by the site-exchange between the cluster and substrate atoms. • The cluster reconstructs the atom arrangement following as the substrate lattice arrangement from bottom to up. • The structural reconstruction ability and scope depend on the cluster size and incident energy. - Abstract: To improve the performance of the Pd composite membrane prepared by the cold spraying technology, it is extremely essential to give insights into the deposition process of the cluster and the heterogeneous deposition of the big Pd cluster at the different incident velocities on the atomic level. The deposition behavior, morphologies, energetic and interfacial configuration were examined by the molecular dynamic simulation and characterized by the cluster flattening ratio, the substrate maximum local temperature, the atom-embedded layer number and the surface-alloy formation. According to the morphology evolution, three deposition stages and the corresponding structural and energy evolution were clearly identified. The cluster deformation and penetrating depth increased with the enhancement of the incident velocity, but the increase degree also depended on the substrate hardness. The interfacial interaction between the cluster and the substrate can be improved by the higher substrate local temperature

Palladium-catalysed direct cross-coupling of secondary alkyllithium reagents

NARCIS (Netherlands)

Vila, Carlos; Giannerini, Massimo; Hornillos, Valentin; Fananas-Mastral, Martin; Feringa, Ben L.

2014-01-01

Palladium-catalysed cross-coupling of secondary C(sp(3)) organometallic reagents has been a long-standing challenge in organic synthesis, due to the problems associated with undesired isomerisation or the formation of reduction products. Based on our recently developed catalytic C-C bond formation

Halide-Enhanced Catalytic Activity of Palladium Nanoparticles Comes at the Expense of Catalyst Recovery

Directory of Open Access Journals (Sweden)

Azzedine Bouleghlimat

2017-09-01

Full Text Available In this communication, we present studies of the oxidative homocoupling of arylboronic acids catalyzed by immobilised palladium nanoparticles in aqueous solution. This reaction is of significant interest because it shares a key transmetallation step with the well-known Suzuki-Miyaura cross-coupling reaction. Additives can have significant effects on catalysis, both in terms of reaction mechanism and recovery of catalytic species, and our aim was to study the effect of added halides on catalytic efficiency and catalyst recovery. Using kinetic studies, we have shown that added halides (added as NaCl and NaBr can increase the catalytic activity of the palladium nanoparticles more than 10-fold, allowing reactions to be completed in less than half a day at 30 °C. However, this increased activity comes at the expense of catalyst recovery. The results are in agreement with a reaction mechanism in which, under conditions involving high concentrations of chloride or bromide, palladium leaching plays an important role. Considering the evidence for analogous reactions occurring on the surface of palladium nanoparticles under different reaction conditions, we conclude that additives can exert a significant effect on the mechanism of reactions catalyzed by nanoparticles, including switching from a surface reaction to a solution reaction. The possibility of this switch in mechanism may also be the cause for the disagreement on this topic in the literature.

Theoretical Study of Palladium Membrane Reactor Performance During Propane Dehydrogenation Using CFD Method

Directory of Open Access Journals (Sweden)

Kamran Ghasemzadeh

2017-04-01

Full Text Available This study presents a 2D-axisymmetric computational fluid dynamic (CFD model to investigate the performance Pd membrane reactor (MR during propane dehydrogenation process for hydrogen production. The proposed CFD model provided the local information of temperature and component concentration for the driving force analysis. After investigation of mesh independency of CFD model, the validation of CFD model results was carried out by other modeling data and a good agreement between CFD model results and theoretical data was achieved. Indeed, in the present model, a tubular reactor with length of 150 mm was considered, in which the Pt-Sn-K/Al2O3 as catalyst were filled in reaction zone. Hence, the effects of the important operating parameter (reaction temperature on the performances of membrane reactor (MR were studied in terms of propane conversion and hydrogen yield. The CFD results showed that the suggested MR system during propane dehydrogenation reaction presents higher performance with respect to once obtained in the conventional reactor (CR. In particular, by applying Pd membrane, was found that propane conversion can be increased from 41% to 49%. Moreover, the highest value of propane conversion (X = 91% was reached in case of Pd-Ag MR. It was also established that the feed flow rate of the MR is to be the one of the most important factors defining efficiency of the propane dehydrogenation process.

Detecting Airborne Mercury by Use of Palladium Chloride

Science.gov (United States)

Ryan, Margaret; Shevade, Abhijit; Kisor, Adam; Homer, Margie; Jewell, April; Manatt, Kenneth; Torres, Julia; Soler, Jessica; Taylor, Charles

2009-01-01

Palladium chloride films have been found to be useful as alternatives to the gold films heretofore used to detect airborne elemental mercury at concentrations of the order of parts per billion (ppb). Somewhat more specifically, when suitably prepared palladium chloride films are exposed to parts-per-billion or larger concentrations of airborne mercury, their electrical resistances change by amounts large enough to be easily measurable. Because airborne mercury adversely affects health, it is desirable to be able to detect it with high sensitivity, especially in enclosed environments in which there is a risk of leakage of mercury from lamps or other equipment. The detection of mercury by use of gold films involves the formation of gold/mercury amalgam. Gold films offer adequate sensitivity for detection of airborne mercury and could easily be integrated into an electronic-nose system designed to operate in the temperature range of 23 to 28 C. Unfortunately, in order to regenerate a gold-film mercury sensor, one must heat it to a temperature of 200 C for several minutes in clean flowing air. In preparation for an experiment to demonstrate the present sensor concept, palladium chloride was deposited from an aqueous solution onto sets of gold electrodes and sintered in air to form a film. Then while using the gold electrodes to measure the electrical resistance of the films, the films were exposed, at a temperature of 25 C, to humidified air containing mercury at various concentrations from 0 to 35 ppb (see figure). The results of this and other experiments have been interpreted as signifying that sensors of this type can detect mercury in room-temperature air at concentrations of at least 2.5 ppb and can readily be regenerated at temperatures <40 C.

Palladium nanoparticles on InP for hydrogen detection

Czech Academy of Sciences Publication Activity Database

Černohorský, Ondřej; Žďánský, Karel; Zavadil, Jiří; Kacerovský, Pavel; Piksová, K.

2011-01-01

Roč. 6, č. 410 (2011), s. 4101-4104 ISSN 1931-7573 R&D Projects: GA AV ČR(CZ) KAN401220801; GA ČR GA102/09/1037 Institutional research plan: CEZ:AV0Z20670512 Keywords : palladium * indium phosphide Subject RIV: JA - Electronics ; Optoelectronics, Electrical Engineering Impact factor: 2.726, year: 2011

Influence of layer compositions and annealing conditions on complete formation of ternary PdAgCu alloys prepared by sequential electroless and electroplating methods

Energy Technology Data Exchange (ETDEWEB)

Sumrunronnasak, Sarocha [Graduate Program of Petrochemistry and Polymer Science, Faculty of Science, Chulalongkorn University, Bangkok 10330 (Thailand); Tantayanon, Supawan, E-mail: supawan.t@chula.ac.th [Green Chemistry Research Laboratory, Department of Chemistry, Faculty of Science, Chulalongkorn University, Bangkok 10330 (Thailand); Kiatgamolchai, Somchai [Department of Physics, Faculty of Science, Chulalongkorn University, Bangkok 10330 (Thailand)

2017-01-01

PdAgCu ternary alloy membranes were synthesized by the sequential electroless plating of Pd following by electroplating of Ag and Cu onto stainless steel substrate. The composition of the composite was varied by changing the deposition times. The fabricated layers were annealed at the temperatures between 500 and 600 °C for 20–60 h. The Energy Dispersive X-ray spectroscopy (EDX) and X-ray diffraction (XRD) were employed to investigate the element distribution in the membrane which provided the insight on membrane alloying process. Complete formation of the alloy could be obtained when the Pd composition was greater than a critical value of 60 wt%, and Ag and Cu contents were in the range of 18–30 wt% and 2–13 wt%, respectively. Deposition times of Ag and Cu were found to affect the completion of alloy formation. Excess amount of the deposited Cu particularly tended to segregate on the surface of the membrane. - Highlights: • Ternary PdAgCu alloy membranes were successfully prepared by the sequential electroless and electroplating methods. • The average Pd composition required to form alloy was found to be approximately at least 60%wt. • The alloy region was achieved for f Pd 60–73 wt%, Cu 18–30 wt% and Ag 2–13 wt%. • Suitable annealing temperature in the range of 500–600 °C for an adequate period of treating time (20–60 h).

A novel high-strength and highly corrosive biodegradable Fe-Pd alloy: Structural, mechanical and in vitro corrosion and cytotoxicity study.

Science.gov (United States)

Čapek, Jaroslav; Msallamová, Šárka; Jablonská, Eva; Lipov, Jan; Vojtěch, Dalibor

2017-10-01

Recently, iron-based materials have been considered as candidates for the fabrication of biodegradable load-bearing implants. Alloying with palladium has been found to be a suitable approach to enhance the insufficient corrosion rate of iron-based alloys. In this work, we have extensively compared the microstructure, the mechanical and corrosion properties, and the cytotoxicity of an FePd2 (wt%) alloy prepared by three different routes - casting, mechanical alloying and spark plasma sintering (SPS), and mechanical alloying and the space holder technique (SHT). The properties of the FePd2 (wt%) were compared with pure Fe prepared in the same processes. The preparation route significantly influenced the material properties. Materials prepared by SPS possessed the highest values of mechanical properties (CYS~750-850MPa) and higher corrosion rates than the casted materials. Materials prepared by SHT contained approximately 60% porosity; therefore, their mechanical properties reached the lowest values, and they had the highest corrosion rates, approximately 0.7-1.2mm/a. Highly porous FePd2 was tested in vitro according to the ISO 10993-5 standard using L929 cells, and two-fold diluted extracts showed acceptable cytocompatibility. In general, alloying with Pd enhanced both mechanical properties and corrosion rates and did not decrease the cytocompatibility of the studied materials. Copyright © 2017 Elsevier B.V. All rights reserved.

Hydrogen storage studies on palladium-doped carbon materials (AC, CB, CNMs) @ metal-organic framework-5.

Science.gov (United States)

Viditha, V; Srilatha, K; Himabindu, V

2016-05-01

Metal organic frameworks (MOFs) are a rapidly growing class of porous materials and are considered as best adsorbents for their high surface area and extraordinary porosity. The MOFs are synthesized by using various chemicals like triethylamine, terepthalic acid, zinc acetate dihydrate, chloroform, and dimethylformamide (DMF). Synthesized MOFs are intercalated with palladium/activated carbon, carbon black, and carbon nanomaterials by chemical reduction method for the purpose of enhancing the hydrogen adsorption capacities. We have observed that the palladium doped activated carbon on MOF-5 showed high hydrogen storage capacity. This may be due to the affinity of the palladium toward hydrogen molecule. The samples are characterized by X-ray diffraction, scanning electron microscopy (SEM), and Brunauer-Emmett-Teller (BET) surface area analysis. We have observed a clear decrease in the BET surface area and pore volume. The obtained results show a better performance for the synthesized sample. To our best knowledge, no one has reported the work on palladium-doped carbon materials (activated carbon, carbon black, carbon nanomaterials) impregnated to the metal-organic framework-5. We have attempted to synthesize carbon nanomaterials using indigenously fabricated chemical vapor deposition (CVD) unit as a support. We have observed an increase in the hydrogen storage capacities.

Enantioconvergent synthesis by sequential asymmetric Horner-Wadsworth-Emmons and palladium-catalyzed allylic substitution reactions

DEFF Research Database (Denmark)

Pedersen, Torben Møller; Hansen, E. Louise; Kane, John

2001-01-01

A new method for enantioconvergent synthesis has been developed. The strategy relies on the combination of an asymmetric Horner-Wadsworth-Emmons (HWE) reaction and a palladium-catalyzed allylic substitution. Different $alpha@-oxygen-substituted, racemic aldehydes were initially transformed by asy...... the allylic stereocenter and the alkene geometry. Thus, a single $gamma@-substituted ester was obtained as the overall product, in high isomeric purity. The method was applied to a synthesis of a subunit of the iejimalides, a group of cytotoxic macrolides.......A new method for enantioconvergent synthesis has been developed. The strategy relies on the combination of an asymmetric Horner-Wadsworth-Emmons (HWE) reaction and a palladium-catalyzed allylic substitution. Different $alpha@-oxygen-substituted, racemic aldehydes were initially transformed...... by asymmetric HWE reactions into mixtures of two major $alpha@,$beta@-unsaturated esters, possessing opposite configurations at their allylic stereocenters as well as opposite alkene geometry. Subsequently, these isomeric mixtures of alkenes could be subjected to palladium-catalyzed allylic substitution...

Controlled deposition of palladium nanodendrites on the tips of gold nanorods and their enhanced catalytic activity.

Science.gov (United States)

Su, Gaoxing; Jiang, Huaqiao; Zhu, Hongyan; Lv, Jing-Jing; Yang, Guohai; Yan, Bing; Zhu, Jun-Jie

2017-08-31

Plasmonic Au-Pd nanostructures have drawn significant attention for use in heterogeneous catalysis. In this study, palladium nanodendrite-tipped gold nanorods (PdND-T-AuNRs) were subjected to a facile fabrication under mild reaction conditions. The palladium amounts on the two tips were tunable. In the preparation of PdND-T-AuNRs, dense capped AuNRs, a low reaction temperature, and suitable stabilizing agents were identified as critical reaction parameters for controlling palladium nanodendrites deposited on both ends of AuNRs. After overgrowth with palladium nanodendrites, the longitudinal surface plasmonic resonance peaks of PdND-T-AuNRs were red-shifted from 810 nm to 980 nm. The electrocatalytic activity of PdND-T-AuNRs for ethanol oxidation was examined, which was a bit weaker than that of cuboid core-shell Au-Pd nanodendrites; however, PdND-T-AuNRs were more stable in ethanol electrooxidation. Moreover, the photocatalytic activity of PdND-T-AuNRs for Suzuki cross-coupling reactions was investigated. At room temperature, nearly 100% yield was obtained under laser irradiation. The results can further enhance our capability of fine-tuning the optical, electronic, and catalytic properties of the bimetallic Au-Pd nanostructures.

Chlorodifluoromethane-triggered formation of difluoromethylated arenes catalysed by palladium

Science.gov (United States)

Feng, Zhang; Min, Qiao-Qiao; Fu, Xia-Ping; An, Lun; Zhang, Xingang

2017-09-01

Difluoromethylated aromatic compounds are of increasing importance in pharmaceuticals, agrochemicals and materials. Chlorodifluoromethane (ClCF2H), an inexpensive, abundant and widely used industrial raw material, represents the ideal and most straightforward difluoromethylating reagent, but introduction of the difluoromethyl group (CF2H) from ClCF2H into aromatics has not been reported. Here, we describe a direct palladium-catalysed difluoromethylation method for coupling ClCF2H with arylboronic acids and esters to generate difluoromethylated arenes with high efficiency. The reaction exhibits a remarkably broad substrate scope, including heteroarylboronic acids, and was used for difluoromethylation of a range of pharmaceuticals and biologically active compounds. Preliminary mechanistic studies revealed that a palladium difluorocarbene intermediate is involved in the reaction. Although numerous metal-difluorocarbene complexes have been prepared, the catalytic synthesis of difluoromethylated or difluoromethylenated compounds involving metal-difluorocarbene complexes has not received much attention. This new reaction therefore also opens the door to understand metal-difluorocarbene complex catalysed reactions.

A Palladium-Tin Modified Microband Electrode Array for Nitrate Determination

Directory of Open Access Journals (Sweden)

Yexiang Fu

2015-09-01

Full Text Available A microband electrode array modified with palladium-tin bimetallic composite has been developed for nitrate determination. The microband electrode array was fabricated by Micro Electro-Mechanical System (MEMS technique. Palladium and tin were electrodeposited successively on the electrode, forming a double-layer structure. The effect of the Pd-Sn composite was investigated and its enhancement of catalytic activity and lifetime was revealed. The Pd-Sn modified electrode showed good linearity (R2 = 0.998 from 1 mg/L to 20 mg/L for nitrate determination with a sensitivity of 398 μA/(mg∙L−1∙cm2. The electrode exhibited a satisfying analytical performance after 60 days of storage, indicating a long lifetime. Good repeatability was also displayed by the Pd-Sn modified electrodes. The results provided an option for nitrate determination in water.

Palladium nanoparticles supported on layered hydroxide salts and their use in carbon-carbon coupling organic reactions

OpenAIRE

Martínez,Maby; Ocampo,Rogelio; Rios,Luz Amalia; Ramírez,Alfonso; Giraldo,Oscar

2011-01-01

Palladium nanoparticles supported on zinc hydroxide salts were prepared by intercalation of [PdCl6]2- and its further reduction with ethanol under reflux. All the materials were completely characterized by atomic absorption spectroscopy (AAS), X-ray diffraction (XRD), thermogravimetric/derivative thermogravimetric (TG/DTG) analyses, scanning electron microscopy (SEM), UV-Visible spectrometry and transmission electron microscopy (TEM). TEM analysis confirmed that the palladium nanoparticles we...

Observation of Binuclear Palladium Clusters Upon ESI-MS Monitoring of the Suzuki-Miyaura Cross-Coupling Catalyzed by a Dichloro-bis(aminophosphine) Complex of Palladium

Czech Academy of Sciences Publication Activity Database

Agrawal, Divya; Schröder, Detlef; Frech, C. M.

2011-01-01

Roč. 30, č. 13 (2011), s. 3579-3587 ISSN 0276-7333 Institutional research plan: CEZ:AV0Z40550506 Keywords : catalysis * C-C coupling * electrospray ionization * palladium * Suzuki-Miyaura coupling Subject RIV: CF - Physical ; Theoretical Chemistry Impact factor: 3.963, year: 2011

Evaluation of colloidal Pd and Pd-alloys as anode electrocatalysts for direct borohydride fuel cells applications

Energy Technology Data Exchange (ETDEWEB)

Atwan, M.H. [General Motors R and D Technical Center, Warren, MI (United States); Gyenge, E.L. [British Columbia Univ., Vancouver, BC (Canada). Dept. of Chemical and Biological Engineering; Northwood, D.O. [Windsor Univ., ON (Canada). Dept. of Mechanical, Automotive and Materials Engineering

2010-07-01

An evaluation was conducted to assess the use of colloidal palladium (Pd) and Pd alloys as anode electrocatalysts for direct borohydride fuel cell applications. A modified Bonneman method was used to investigate borohydride oxidation on supported Pd and Pd-alloy nano-electrocatalysts. Cyclic voltammetry (CV), rotating disk electrode (RDE) voltammetry, and single fuel cell test stations were used to determine Tafel slopes, exchange current densities, oxidation peak potentials, and fuel cell performance. The study also investigated the influence of temperature and oxidant flow and fuel flow rates on fuel cell performance. The study showed that the current density of the fuel cell increased with increases in temperature for all the investigated Pd electrocatalysts. However, the increase in current density was not as high as expected when fuel flow rates were increased. A current density of 50 mA cm{sup -2} was observed at 298 K with a Pd-Ir anode catalyst operating at a cell voltage of 0.5 V. 28 refs., 1 tab., 15 figs.

Development and Characterization of Improved NiTiPd High-Temperature Shape-Memory Alloys by Solid-Solution Strengthening and Thermomechanical Processing

Science.gov (United States)

Bigelow, Glen; Noebe, Ronald; Padula, Santo, II; Garg, Anita; Olson, David

2006-01-01

The need for compact, solid-state actuation systems for use in the aerospace, automotive, and other transportation industries is currently motivating research in high-temperature shape-memory alloys (HTSMA) with transformation temperatures greater than 100 C. One of the basic high-temperature alloys investigated to fill this need is Ni(19.5)Ti(50.5)Pd30. Initial testing has indicated that this alloy, while having acceptable work characteristics, suffers from significant permanent deformation (or ratcheting) during thermal cycling under load. In an effort to overcome this deficiency, various solid-solution alloying and thermomechanical processing schemes were investigated. Solid-solution strengthening was achieved by substituting 5at% gold or platinum for palladium in Ni(19.5)Ti(50.5)Pd30, the so-called baseline alloy, to strengthen the martensite and austenite phases against slip processes and improve thermomechanical behavior. Tensile properties, work behavior, and dimensional stability during repeated thermal cycling under load for the ternary and quaternary alloys were compared. The relative difference in yield strength between the martensite and austenite phases and the dimensional stability of the alloy were improved by the quaternary additions, while work output was only minimally impacted. The three alloys were also thermomechanically processed by cycling repeatedly through the transformation range under a constant stress. This so-called training process dramatically improved the dimensional stability in these samples and also recovered the slight decrease in work output caused by quaternary alloying. An added benefit of the solid-solution strengthening was maintenance of enhanced dimensional stability of the trained material to higher temperatures compared to the baseline alloy, providing a greater measure of over-temperature capability.

Cellulose acetate membranes functionalized with resveratrol by covalent immobilization for improved osseointegration

Science.gov (United States)

Pandele, A. M.; Neacsu, P.; Cimpean, A.; Staras, A. I.; Miculescu, F.; Iordache, A.; Voicu, S. I.; Thakur, V. K.; Toader, O. D.

2018-04-01

Covalent immobilization of resveratrol onto cellulose acetate polymeric membranes used as coating on a Mg-1Ca-0.2Mn-0.6Zr alloy is presented for potential application in the improvement of osseointegration processes. For this purpose, cellulose acetate membrane is hydrolysed in the presence of potassium hydroxide, followed by covalent immobilization of aminopropyl triethoxy silane. Resveratrol was immobilized onto membranes using glutaraldehyde as linker. The newly synthesised functional membranes were thoroughly characterized for their structural characteristics determination employing X-ray photoelectron spectroscopy (XPS), infrared spectroscopy (FT-IR), Raman spectroscopy, thermogravimetric analysis (TGA/DTG) and scanning electron microscopy (SEM) techniques. Subsequently, in vitro cellular tests were performed for evaluating the cytotoxicity biocompatibility of synthesized materials and also the osseointegration potential of obtained derivatised membrane material. It was demonstrated that both polymeric membranes support viability and proliferation of the pre-osteoblastic MC3T3-E1 cells, thus providing a good protection against the potential harmful effects of the compounds released from coated alloys. Furthermore, cellulose acetate membrane functionalized with resveratrol exhibits a significant increase in alkaline phosphatase activity and extracellular matrix mineralization, suggesting its suitability to function as an implant surface coating for guided bone regeneration.

Ester versus polyketone formation in the palladium-diphosphine catalyzed carbonylation of ethene.

Science.gov (United States)

Zuidema, Erik; Bo, Carles; van Leeuwen, Piet W N M

2007-04-04

The origin of the chemoselectivity of palladium catalysts containing bidentate phosphine ligands toward either methoxycarbonylation of ethene or the copolymerization of ethene and carbon monoxide was investigated using density functional theory based calculations. For a palladium catalyst containing the electron-donating bis(dimethylphosphino)ethane (dmpe) ligand, the rate determining step for chain propagation is shown to be the insertion of ethene into the metal-acyl bond. The high barrier for chain propagation is attributed to the low stability of the ethene intermediate, (dmpe)Pd(ethene)(C(O)CH3). For the competing methanolysis process, the most likely pathway involves the formation of (dmpe)Pd(CH3OH)(C(O)CH3) via dissociative ligand exchange, followed by a solvent mediated proton-transfer/reductive- elimination process. The overall barrier for this process is higher than the barrier for ethene insertion into the palladium-acetyl bond, in line with the experimentally observed preference of this type of catalyst toward the formation of polyketone. Electronic bite angle effects on the rates of ethene insertion and ethanoyl methanolysis were evaluated using four electronically and sterically related ligands (Me)2P(CH2)nP(Me)2 (n = 1-4). Steric effects were studied for larger tert-butyl substituted ligands using a QM/MM methodology. The results show that ethene coordination to the metal center and subsequent insertion into the palladium-ethanoyl bond are disfavored by the addition of steric bulk around the metal center. Key intermediates in the methanolysis mechanism, on the other hand, are stabilized because of electronic effects caused by increasing the bite angle of the diphosphine ligand. The combined effects explain successfully which ligands give polymer and which ones give methyl propionate as the major products of the reaction.

A Facile Synthesis of Hollow Palladium/Copper Alloy Nanocubes Supported on N-Doped Graphene for Ethanol Electrooxidation Catalyst

Directory of Open Access Journals (Sweden)

Zhengyu Bai

2015-04-01

Full Text Available In this paper, a catalyst of hollow PdCu alloy nanocubes supported on nitrogen-doped graphene support (H-PdCu/ppy-NG is successfully synthesized using a simple one-pot template-free method. Two other catalyst materials such as solid PdCu alloy particles supported on this same nitrogen-doped graphene support (PdCu/ppy-NG and hollow PdCu alloy nanocubes supported on the reduced graphene oxide support (H-PdCu/RGO are also prepared using the similar synthesis conditions for comparison. It is found that, among these three catalyst materials, H-PdCu/ppy-NG gives the highest electrochemical active area and both the most uniformity and dispersibility of H-PdCu particles. Electrochemical tests show that the H-PdCu/ppy-NG catalyst can give the best electrocatalytic activity and stability towards the ethanol electrooxidation when compared to other two catalysts. Therefore, H-PdCu/ppy-NG should be a promising catalyst candidate for anodic ethanol oxidation in direct ethanol fuel cells.

Recovery of palladium, cesium, and selenium from heavy metal alkali borosilicate glass by combination of heat treatment and leaching processes

Energy Technology Data Exchange (ETDEWEB)

Xu, Zhanglian; Okada, Takashi, E-mail: t-okada@u-fukui.ac.jp; Nishimura, Fumihiro; Yonezawa, Susumu

2017-06-05

Highlights: • A separation technique of both noble and less noble metal from glass is studied. • Via reductive heat treatment, 80% of palladium is extracted in liquid bismuth. • Sodium–potassium-rich materials with cesium and selenium are phase separated. • From the materials, over 80% of cesium and selenium are extracted in water. - Abstract: Reductive heat-treatment and leaching process were applied to a simulated lead or bismuth soda-potash-borosilicate glass with palladium, cesium, and selenium to separate these elements. In the reductive heat treatment, palladium is extracted in liquid heavy metal phase generated by the reduction of the heavy metal oxides, whereas cesium and selenium are concentrated in phase separated Na–K-rich materials on the glass surface. From the materials, cesium and selenium can be extracted in water, and the selenium extraction was higher in the treatment of the bismuth containing glass. The chemical forms of palladium in the glass affected the extraction efficiencies of cesium and selenium. Among the examined conditions, in the bismuth glass treatment, the cesium and selenium extraction efficiencies in water were over 80%, and that of palladium in liquid bismuth was over 80%.

Fabrication and characterization of magnetic composite membrane pressure sensor

KAUST Repository

Khan, Mohammed Asadullah

2016-04-20

This paper describes a magnetic field powered pressure sensor, which comprises a coil array and a magnetic composite membrane. The composite membrane is made by embedding a ribbon of the amorphous soft magnetic alloy Vitrovac®, in a 17 mm x 25 mm x 1.5 mm Polydimethylsiloxane (PDMS) layer. PDMS is chosen for its low Young\\'s modulus and the amorphous alloy for its high permeability. The membrane is suspended 1.5 mm above a 17x19 array of microfabricated planar coils. The coils are fabricated by patterning a 620 nm thick gold layer. Each coil occupies an area of 36000 μm2 and consists of 14 turns. The sensor is tested by subjecting it to pressure and simultaneously exciting it by a 24 A/m, 100 kHz magnetic field. A pressure change from 0 kPa to 5.1 kPa, results in a 5400 ppm change in the voltage output.

Fabrication and characterization of magnetic composite membrane pressure sensor

KAUST Repository

Khan, Mohammed Asadullah; Alfadhel, Ahmed; Kosel, Jü rgen; Bakolka, M.

2016-01-01

This paper describes a magnetic field powered pressure sensor, which comprises a coil array and a magnetic composite membrane. The composite membrane is made by embedding a ribbon of the amorphous soft magnetic alloy Vitrovac®, in a 17 mm x 25 mm x 1.5 mm Polydimethylsiloxane (PDMS) layer. PDMS is chosen for its low Young's modulus and the amorphous alloy for its high permeability. The membrane is suspended 1.5 mm above a 17x19 array of microfabricated planar coils. The coils are fabricated by patterning a 620 nm thick gold layer. Each coil occupies an area of 36000 μm2 and consists of 14 turns. The sensor is tested by subjecting it to pressure and simultaneously exciting it by a 24 A/m, 100 kHz magnetic field. A pressure change from 0 kPa to 5.1 kPa, results in a 5400 ppm change in the voltage output.

Compensation effect in H 2 permeation kinetics of PdAg membranes

KAUST Repository

Zeng, Gaofeng

2012-08-30

Knowledge about the (inter)dependence of permeation kinetic parameters on the stoichiometry of H 2-selective alloys is still rudimentary, although uncovering the underlying systematic correlations will greatly facilitate current efforts into the design of novel high-performance H 2 separation membranes. Permeation measurements with carefully engineered, 2-7 μm thick supported Pd 100-xAg x membranes reveal that the activation energy and pre-exponential factor of H 2 permeation laws vary systematically with alloy composition, and both kinetic parameters are strongly correlated for x ≤ 50. We show that this permeation kinetic compensation effect corresponds well with similar correlations in the hydrogen solution thermodynamics and diffusion kinetics of PdAg alloys that govern H 2 permeation rates. This effect enables the consistent description of permeation characteristics over wide temperature and alloy stoichiometry ranges, whereas hydrogen solution thermodynamics may play a role, too, as a yet unrecognized source of kinetic compensation in, for example, H 2-involving reactions over metal catalysts or hydrogenation/ dehydrogenation of hydrogen storage materials. © 2012 American Chemical Society.

Synthesis of pyrrolo(2,3-b)quinolines by palladium-catalyzed heteroannulation

International Nuclear Information System (INIS)

Gee, Moon Bae; Lee, Won Jung; Yum, Eul Kgun

2003-01-01

Palladium-catalyzed heteroannulation of 2-amino-3-iodoquinoline derivatives and 1-trimethylsilyl internal alkynes provided highly regioselective pyrrolo(2,3-b)quinolines with trimethylsilyl group next to the nitrogen atom in the pyrrole ring

New experimental set-up and procedure for analyzing the dynamics of permeation of H2(g) across Pd-based metallic membranes

International Nuclear Information System (INIS)

Decaux, C.; Millet, P.; Decaux, C.

2006-01-01

Hydrogen permeation through metallic membranes is an industrial process used for purification purposes. Palladium-based alloys are generally used as permeation materials at operating temperatures above the critical value so that the metal-H system remains monophasic and that diffusion proceeds at sufficient rate. In state of the art systems, metallic membranes with typical thickness of a few tens of microns are used and rate limitation are generally attributed to atomic H transport by diffusion. Because of cost considerations, it is necessary to reduce the thickness of these membranes. In the micron thick range, surface contributions are expected to become rate determining, or at least to play an increasing role. Further, when the membrane is used on the exit side of a gas reformer to directly extract hydrogen, corrosion problems are expected to occur on the upstream side of the membrane. For all these reasons, there is a need to separately measure surface and bulk (diffusion) rate contributions to the overall permeation flux. A new experimental equipment has been specifically designed for this purpose. This setup can be operated in two different modes: for sorption or permeation experiments. In a typical sorption experiment, the metallic membrane is disposed in the reaction chamber and hydrogen is allowed to react from both side of the surface. This procedure allows the separate measurement of surface absorption and desorption resistances associated with the chemisorption step. In a typical permeation experiment, the membrane is mounted between two volume chambers, a pressurized hydrogen source reservoir and an empty sink reservoir. Initially, a difference of pressure is set between the two reservoirs. When the valve of the source tank is opened, H 2 (g) flows to the membrane and permeation proceeds until pressure reaches an equilibrium value. In both experimental configurations, gas pressure transients are synchronously sampled all along the experiment

Palladium extraction by a malonamide: behavior and particularities compared to rare earths

International Nuclear Information System (INIS)

Poirot, Remi

2014-01-01

Recycling of valuable metals appears as a solution of growing interest for a sustainable supply strategy nowadays. Palladium (Pd), along with other platinum group metals (PGM) and rare earth elements (REEs), represents one of the crucial issues in recovery processes. Malonamides are neutral amphiphilic molecules which have proved their potency for the extraction of lanthanides. These extractants in nitric media were thoroughly studied in frame of nuclear fuel treatment towards lanthanide-actinide separation. Within this framework, our purpose was to study liquid/liquid (L/L) extraction towards Pd recovery from nitric media by a malonamide: the DMDOHEMA. Various parameters such as as equilibration time, pH, extractant and nitrate concentrations were investigated in detail. In some experimental conditions, a Pd-rich solid third phase appears at the interface. These third phases were deeply analyzed with NMR, IR and XPS. Mechanistic studies involved complete analysis of the organic phases, including chemical speciation at the molecular level (coordination chemistry with NMR, IR, XRD), and supramolecular ordering characterization (with SAXS and NMR). Palladium complexes were identified and characterized. Similarities and differences between palladium and lanthanides behavior during extraction were evidenced and both can be efficiently co-extracted or separated according to different experimental conditions. (author) [fr

Studies on the preparation of 109Pd and 111Ag by (n,γ) reactions on natural palladium for possible applications in radionuclide therapy

International Nuclear Information System (INIS)

Vimalnath, K.V.; Chirayil, Viju; Saha, Sujata

2007-01-01

Natural palladium on neutron activation provided two radionuclides viz 111 Ag and 109 Pd with attractive nuclear properties for use in radionuclide therapy applications in nuclear medicine. 109 Pd (t 1/2 13.7h, E βmax 1.03MeV) was produced by neutron activation of 108 Pd, while in the same target 111 Ag (t 1/2 7.45d, E βmax 1.04MeV) is formed by the beta decay of co-produced radioactive 111 Pd. Measured samples of palladium foils were neutron irradiated in Dhruva reactor for 7d at a flux of 9 x 10 13 n.cm -2 .s -1 . Radioactive palladium and silver were separated by ion-exchange chromatography over Dowex 1x8, 200-400 mesh size anion exchanger column. Radiochemical mixture of palladium and silver loaded in 10M HCl acid medium showed retention of palladium, while silver eluted out freely. The separated radionuclidically pure fractions of 109 Pd and 111 Ag activity were reconstituted as chloride and nitrate solutions respectively. About 133 GBq 109 Pd and 930 MBq of 111 Ag activity were produced from 100mg palladium. (author)

Performance of Pd on activated carbon as hydrogen electrode with respect to hydrogen yield in a single cell proton exchange membrane (PEM) water electrolyser

Energy Technology Data Exchange (ETDEWEB)

Naga Mahesh, K.; Sarada Prasad, J.; Venkateswer Rao, M.; Himabindu, V. [Centre for Environment, Institute of Science and Technology, Jawaharlal Nehru Technological University Hyderabad, Kukatpally, Hyderabad 500085 (A.P.) (India); Yerramilli, Anjaneyulu [TLGVRC, JSU Box 18739, Jackson State University, Jackson, MS 32917 - 0939 (United States); Raghunathan Rao, P. [Fuel cell section, Heavy Water Division, Bhabha Atomic Research Centre, Trombay, Mumbai - 400 085 (India)

2009-08-15

Palladium (Pd) on activated carbon is used as electrocatalyst coated on Nafion 115 membrane as Hydrogen electrode and RuO{sub 2} is coated on other side of membrane used as oxygen electrode. 5 wt% and 10 wt% Pd on activated carbon is prepared as membrane electrode assembly (MEA) and investigated the performance of the same using inhouse prepared 10 cm{sup 2} single cell. The performance of the single cell assembly and the hydrogen yield are reported during electrolysis operation at temperatures 27 C, 45 C and 65 C at 0.1, 0.2, 0.3, 0.4, 0.5 A/cm{sup 2} current densities with respect to voltages. (author)

Modelling of fast hydrogen permeability of alloys for membrane gas separation

Science.gov (United States)

Zaika, Yu. V.; Rodchenkova, N. I.

2017-05-01

The method of measuring the specific hydrogen permeability is used to study various alloys that are promising for gas separation installations. The nonlinear boundary value problem of hydrogen permeability complying with the specific features of the experiment and its modifications taking into account the high transfer rate is presented. Substantial difference from the quasi-equilibrium model (Richardson approximation in the assumption of the equilibrium Sieverts' law near the surface) has been discussed. The model is tested on published experimental data on Ta77Nb23 alloy.

Prefunctionalized Porous Organic Polymers: Effective Supports of Surface Palladium Nanoparticles for the Enhancement of Catalytic Performances in Dehalogenation.

Science.gov (United States)

Zhong, Hong; Liu, Caiping; Zhou, Hanghui; Wang, Yangxin; Wang, Ruihu

2016-08-22

Three porous organic polymers (POPs) containing H, COOMe, and COO(-) groups at 2,6-bis(1,2,3-triazol-4-yl)pyridyl (BTP) units (i.e., POP-1, POP-2, and POP-3, respectively) were prepared for the immobilization of metal nanoparticles (NPs). The ultrafine palladium NPs are uniformly encapsulated in the interior pores of POP-1, whereas uniform- and dual-distributed palladium NPs are located on the external surface of POP-2 and POP-3, respectively. The presence of carboxylate groups not only endows POP-3 an outstanding dispersibility in H2 O/EtOH, but also enables the palladium NPs at the surface to show the highest catalytic activity, stability, and recyclability in dehalogenation reactions of chlorobenzene at 25 °C. The palladium NPs on the external surface are effectively stabilized by the functionalized POPs containing BTP units and carboxylate groups, which provides a new insight for highly efficient catalytic systems based on surface metal NPs of porous materials. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Investigation of short-lived neutron-rich palladium and silver isotopes after fast chemical separation from fission fragments

International Nuclear Information System (INIS)

Bruechle, W.

1976-01-01

In this paper, chemical separation processes are described permitting fast and neat isolation of short-lived palladium and silver nuclides from fusion product mixtures. The process for palladium is based on the stability of palladium diethyldithiophosphate. From fission products of the reactions 238 U(n,f) and 249 Cf(nth,f), the following palladium niclides could be studied for the first time by gamma spectroscopy: 1.66 min 113 Pd, 2.45 min 114 Pd, 29 sec sup(115a)Pd, 54 sec sup(115b)Pd, 12.5 sec 116 Pd. 113 Pd could also be indentified according to the reaction 116 Cd(n,α) 113 Pd. The separation of silver is based on the fast isotopic exchange on AgCl. With this process, the following nuclides have been separated from fission product mixtures and studied by gamma spectroscopy: 70 sec sup(113m)Ag, 5.0 sec 114 Ag, 19.2 sec sup(115m)Ag, 2.65 min sup(116g)Ag, 10.5 sec sup(116m)Ag, 1.3 min sup(117g)Ag, 6.0 sec sup(117m)Ag, 4.0 sec 118 Ag. (orig./WL) [de

Palladium mixed-metal surface-modified AB₅-type intermetallides enhance hydrogen sorption kinetics

Directory of Open Access Journals (Sweden)

Roman V. Denys

2010-09-01

Full Text Available Surface engineering approaches were adopted in the preparation of advanced hydrogen sorption materials, based on ‘low-temperature’, AB₅-type intermetallides. The approaches investigated included micro-encapsulation with palladium and mixed-metal mantles using electroless plating. The influence of micro-encapsulation on the surface morphology and kinetics of hydrogen charging were investigated. It was found that palladium-nickel (Pd-Ni co-deposition by electroless plating significantly improved the kinetics of hydrogen charging of the AB₅-type intermetallides at low hydrogen pressure and temperature, after long-term pre-exposure to air. The improvement in the kinetics of hydrogen charging was credited to a synergistic effect between the palladium and nickel atoms in the catalytic mantle and the formation of an ‘interfacial bridge’ for hydrogen diffusion by the nickel atoms in the deposited layer. The developed surface-modified materials may find application in highly selective hydrogen extraction, purification, and storage from impure hydrogen feeds.

Thermogravimetric determination of the enthalpy of astatine and radon adsorption on palladium surfaces

International Nuclear Information System (INIS)

Eichler, B.; Son Chun, K.

1985-01-01

In order to investigate the adsorption of astatine and radon on a palladium surface some on- and off-line thermochromatographic experiments were carried out with 210 At and 220 Rn tracers. The partial molar adsorption enthalpy for zero covering was found to be ΔH/sub a//sup 0, loc./(At) = -(15S +- 10) kJ mole -1 and ΔH/sub a//sup 0, mob./(Rn) = -(37 +- 4) kJ mole -1 . The results are compared with theoretical and experimental values for other elements of the sixth period. The adsorption behaviour of At is in conformity with that of the p-metals on a palladium surface. (author)

Novel O N N Pyrazolyl-imine and Imidazolyl-imine Pincer Palladium ...

African Journals Online (AJOL)

NICO

pincer palladium complexes in Heck coupling reactions. The general form of .... while single crystals suitable for X-ray analyses of complexes 1–4 were grown by ...... non-hydrogen atoms were refined with anisotropic displacement coefficients.

Phase transformation and magnetic anisotropy of an iron-palladium ferromagnetic shape-memory alloy

International Nuclear Information System (INIS)

Cui, J.; Shield, T.W.; James, R.D.

2004-01-01

Martensitic phase transformations in an Fe 7 Pd 3 alloy were studied using various experimental techniques: visual observation, differential scanning calorimeter (DSC) measurements and X-ray diffraction. Magnetic measurements on this alloy were made using a vibrating sample magnetometer (VSM) and a Susceptibility Kappa bridge. The VSM measurements were made with the sample in a compression fixture to bias the martensite phase to a single variant. Both X-ray and DSC measurements show that the FCC-FCT transformation is a weak first-order thermoelastic transition. The average lattice parameters are a=3.822±0.001 A and c=3.630±0.001 A for the FCT martensite, and a 0 =3.756±0.001 A for the FCC austenite. The latent heat of the FCC-FCT transformation is 10.79±0.01 J/cm 3 . A Susceptibility Kappa bridge measurement determined the Curie temperature to be 450 deg. C. The saturation magnetization from VSM data is m s =1220±10 emu/cm 3 at -20 deg. C for the martensite and m s =1080±10 emu/cm 3 at 60 deg. C for the austenite. The easy axes of a single variant of FCT martensite are the [1 0 0] and [0 1 0] directions (the a-axes of the FCT lattice) and the [0 0 1] direction (FCT c-axis) is the hard direction. The cubic magnetic anisotropy constant K 1 is -5±2x10 3 erg/cm 3 for the austenite at 60 deg. C, and the tetragonal anisotropy constant K 1 +K 2 is 3.41 ± 0.02 x 10 5 erg/cm 3 for the martensite at a temperature of -20 deg. C and under 8 MPa of compressive stress in the [0 0 1] direction

Synthesis of honeycomb-like palladium nanostructures by using cucurbit[7]uril and their catalytic activities for reduction of 4-nitrophenol

Energy Technology Data Exchange (ETDEWEB)

Premkumar, Thathan [Department of Materials Science and Engineering, Gwangju Institute of Science and Technology (GIST), 1 Oryong-dong, Buk-gu, Gwangju 500-712 (Korea, Republic of); The University College/Department of Chemistry, Sungkyunkwan University, Suwon 440-746 (Korea, Republic of); Geckeler, Kurt E., E-mail: keg@gist.ac.kr [Department of Materials Science and Engineering, Gwangju Institute of Science and Technology (GIST), 1 Oryong-dong, Buk-gu, Gwangju 500-712 (Korea, Republic of); Department of Nanobio Materials and Electronics (WCU), Gwangju Institute of Science and Technology (GIST), 1 Oryong-dong, Buk-gu, Gwangju 500-712 (Korea, Republic of)

2014-12-15

An eco-friendly one-pot method to synthesize self-assembled palladium nanoclusters using a macrocycle, namely cucurbit[7]uril, in the alkaline medium without employing any special reducing or capping agents and/or external energy at room temperature is described. This greener approach, which utilizes water as a benign solvent and biocompatible cucurbit[7]uril as both reducing and protecting agents, can be applied to synthesize other noble metal nanoparticles such as gold, silver, and platinum. Owing to unique structural arrangement of cucurbit[7]uril, it was possible to prepare palladium nanoclusters of honeycomb-like structure irrespective of the reaction conditions. The honeycomb-like palladium nanoclusters were characterized using transmission electron microscopy (TEM), higher-resolution TEM (HR-TEM), X-ray diffraction (XRD), thermogravimetric analysis (TGA), UV–vis, and FT-IR spectroscopy. Significantly, the synthesized palladium nanoclusters exhibited catalytic activity for the reduction reaction of 4-nitrophenol at room temperature. The approach launched here is easy, green, and user-friendly in contrast to the conventional techniques using polymers or surfactants and harsh reductants. - Highlights: • A simple and one-pot method to synthesis palladium nanostructures with honey-comb like structure. • The strategy established here does not require any harsh and toxic reducing agents. • It has a potential to be a general method for the synthesis of metal nanoparticles in water medium. • Palladium nanoclusters can be used as catalyst for the reduction reaction of 4-nitrophenol. • This system makes a novel platform for industrial and biomedical applications.

Synthesis and characterization of PEFC membranes based on fluorinated-polymer-alloy using pre-soft-EB grafting method

International Nuclear Information System (INIS)

Muto, Fumihiro; Oshima, Akihiro; Kakigi, Tomoyuki; Mitani, Naohiro; Matsuura, Akio; Fujii, Kazuki; Sato, Yukiko; Li Jingye; Washio, Masakazu

2007-01-01

Polymer electrolyte fuel cell (PEFC) membranes based on thin film of crosslinked perfluorinated polymer-alloys (RX-FA) have been fabricated by soft electron beam (soft-EB) grafting with styrene monomers using soft-EB irradiation under nitrogen atmosphere at room temperature (RT). The characteristic properties of styrene-grafted materials (GRX-FA) and sulfonated materials (SRX-FA) have been measured by differential scanning calorimetry (DSC) and FT-IR spectroscopy, ionic conductivity and so on. The glass transition temperatures (dry state) of all obtained SRX-FA were about 105 ± 1 deg. C, which are higher than Nafion. The ion exchange capacities of SRX-FA have been achieved about 3.3 meq/g (dry). The ionic conductivity of obtained SRX-FA has showed about 0.17 S/cm at 60 deg. C with relative humidity (RH) of ∼95%. The ionic conductivities of the obtained SRX-FA were higher than that of conventional perfluoro-sulfonic acid membranes (PFSA). Fabricated membrane electrode assemblies (MEAs) based on the obtained SRX-FA have shown encouraging performance in the PEFC, compared with the conventional PFSA. The power density of obtained MEAs based on the SRX-FA was about 330-340 mW/cm 2 under 500 mA/cm 2 at 60 deg. C operation. Moreover, the maximum power densities of obtained MEAs based on the SRX-FA shows about 630 mW/cm 2 at 60 deg. C. On the other hand, the power density at 500 mA/cm 2 and maximum power density of MEA based on Nafion 112 were about 320 and 590 mW/cm 2 at 60 deg. C. Thus, the power density of the obtained SRX-FA was higher than that of conventional PFSA

Synthesis of phenanthridines via palladium-catalyzed picolinamide-directed sequential C–H functionalization

Directory of Open Access Journals (Sweden)

Ryan Pearson

2013-05-01

Full Text Available We report a new synthesis of phenanthridines based on palladium-catalyzed picolinamide-directed sequential C–H functionalization reactions starting from readily available benzylamine and aryl iodide precursors. Under the catalysis of Pd(OAc2, the ortho-C–H bond of benzylpicolinamides is first arylated with an aryl iodide. The resulting biaryl compound is then subjected to palladium-catalyzed picolinamide-directed intramolecular dehydrogenative C–H amination with PhI(OAc2 oxidant to form the corresponding cyclized dihydrophenanthridines. The benzylic position of these dihydrophenanthridines could be further oxidized with Cu(OAc2, removing the picolinamide group and providing phenathridine products. The cyclization and oxidation could be carried out in a single step and afford phenathridines in moderate to good yields.

Advanced Hydrogen Transport Membrane for Coal Gasification

Energy Technology Data Exchange (ETDEWEB)

Schwartz, Joseph [Praxair, Inc., Tonawanda, NY (United States); Porter, Jason [Colorado School of Mines, Golden, CO (United States); Patki, Neil [Colorado School of Mines, Golden, CO (United States); Kelley, Madison [Colorado School of Mines, Golden, CO (United States); Stanislowski, Josh [Univ. of North Dakota, Grand Forks, ND (United States); Tolbert, Scott [Univ. of North Dakota, Grand Forks, ND (United States); Way, J. Douglas [Colorado School of Mines, Golden, CO (United States); Makuch, David [Praxair, Inc., Tonawanda, NY (United States)

2015-12-23

A pilot-scale hydrogen transport membrane (HTM) separator was built that incorporated 98 membranes that were each 24 inches long. This separator used an advanced design to minimize the impact of concentration polarization and separated over 1000 scfh of hydrogen from a hydrogen-nitrogen feed of 5000 scfh that contained 30% hydrogen. This mixture was chosen because it was representative of the hydrogen concentration expected in coal gasification. When tested with an operating gasifier, the hydrogen concentration was lower and contaminants in the syngas adversely impacted membrane performance. All 98 membranes survived the test, but flux was lower than expected. Improved ceramic substrates were produced that have small surface pores to enable membrane production and large pores in the bulk of the substrate to allow high flux. Pd-Au was chosen as the membrane alloy because of its resistance to sulfur contamination and good flux. Processes were developed to produce a large quantity of long membranes for use in the demonstration test.

Confined palladium colloids in mesoporous frameworks for carbon nanotube growth

NARCIS (Netherlands)

Berenguer-Murcia, A.; Rebrov, E.V.; Cabaj, M.; Wheatley, A.E.H.; Johnson, B.F.G.; Robertson, J.; Schouten, J.C.

2009-01-01

Palladium colloidal nanoparticles with an average size of approximately 2.4 nm have been incorporated into mesoporous inorganic thin films following a multistep approach. This involves the deposition of mesoporous titania thin films with a thickness of 200 nm by spin-coating on titanium plates with

Simple one-pot synthesis of platinum-palladium nanoflowers with enhanced catalytic activity and methanol-tolerance for oxygen reduction in acid media

International Nuclear Information System (INIS)

Zheng, Jie-Ning; He, Li-Li; Chen, Fang-Yi; Wang, Ai-Jun; Xue, Meng-Wei; Feng, Jiu-Ju

2014-01-01

Graphical abstract: PtPd nanoflowers were fabricated by one-pot solvothermal co-reduction method in oleylamine system, which exhibited the improved electrocatalytic activity and higher methanol tolerance for oxygen reduction, compared with commercial Pt and Pd black catalysts. - Highlights: • Bimetallic alloyed PtPd nanoflowers are prepared by a simple one-pot solvothermal co-reduction method. • PtPd nanoflowers display high catalytic performance for ORR dominated by a four-electron pathway. • PtPd nanoflowers show good methanol tolerance for ORR. - Abstract: In this work, bimetallic alloyed platinum-palladium (PtPd) nanoflowers are fabricated by one-pot solvothermal co-reduction of Pt (II) acetylacetonate and Pd (II) acetylacetonate in oleylamine system. The as-prepared nanostructures show the enhanced electrocatalytic activity for oxygen reduction reaction (ORR), dominated by a four-electron pathway based on the Koutecky-Levich plots, mainly owing to the inhibition of the formation of Pt–OH ad via the downshift of d-band center for Pt. Meanwhile, PtPd nanoflowers display good methanol tolerance and improved stability for ORR. The chronoamperometry test reveals that the current of PtPd nanoflowers remains 45.9% of its original value within 6000 s, much higher than those of commercial Pt (36.7%) and Pd (32.2%) black catalysts. Therefore, PtPd nanoflowers with unique interconnected structures can be used as a promising cathode catalyst in direct methanol fuel cells

Tapered Optical Fiber Functionalized with Palladium Nanoparticles by Drop Casting and Laser Radiation for H₂ and Volatile Organic Compounds Sensing Purposes.

Science.gov (United States)

González-Sierra, Nancy Elizabeth; Gómez-Pavón, Luz Del Carmen; Pérez-Sánchez, Gerardo Francisco; Luis-Ramos, Arnulfo; Zaca-Morán, Plácido; Muñoz-Pacheco, Jesús Manuel; Chávez-Ramírez, Francisco

2017-09-06

A comparative study on the sensing properties of a tapered optical fiber pristine and functionalized with the palladium nanoparticles to hydrogen and volatile organic compounds (VOCs), is presented. The sensor response and, response/recovery times were extracted from the measurements of the transient response of the device. The tapered optical fiber sensor was fabricated using a single-mode optical fiber by the flame-brushing technique. Functionalization of the optical fiber was performed using an aqueous solution of palladium chloride by drop-casting technique assisted for laser radiation. The detection principle of the sensor is based on the changes in the optical properties of palladium nanoparticles when exposed to reducing gases, which causes a variation in the absorption of evanescent waves. A continuous wave laser diode operating at 1550 nm is used for the sensor characterization. The sensor functionalized with palladium nanoparticles by this technique is viable for the sensing of hydrogen and VOCs, since it shows an enhancement in sensor response and response time compared to the sensor based on the pristine optical microfiber. The results show that the fabricated sensor is competitive with other fiber optic sensors functionalized with palladium nanoparticles to the hydrogen.

Sonogashira Coupling Reaction with Palladium Powder and Potassium Fluoride in Methanol

Institute of Scientific and Technical Information of China (English)

王磊; 李品华

2003-01-01

A Sonogashira coupling reaction of aromatic halides with terminal alkynes in the presence of palladium powder,potassium fluoride,cuprous iodide and triphenylphosphine in methanol,giving the corresponding coupling products aryl alkynes in good to excellent yiekls,was investigated.

Long-life fatigue test results for two nickel-base structural alloys

International Nuclear Information System (INIS)

Mowbray, D.F.; Giaquinto, E.V.; Mehringer, F.J.

1978-11-01

The results are reported of fatigue tests on two nickel--base alloys, hot-cold-worked and stress-relieved nickel--chrome--iron Alloy 600 and mill-annealed nickel--chrome--moly--iron Alloy 625 in which S-N data were obtained in the life range of 10 6 to 10 10 cycles. The tests were conducted in air at 600 0 F, in the reversed membrane loading mode, at a frequency of approx. 1850 Hz. An electromagnetic, closed loop servo-controlled machine was built to perform the tests. A description of the machine is given

Interaction of CO with Palladium Supported on Oxidized Tungsten

Czech Academy of Sciences Publication Activity Database

Jirka, Ivan; Plšek, Jan; Šutara, F.; Matolín, V.; Cháb, Vladimír; Prince, K. C.

2006-01-01

Roč. 110, č. 47 (2006), s. 23837-23844 ISSN 1520-6106 R&D Projects: GA ČR GA202/05/0244; GA AV ČR IAA1010413 Institutional research plan: CEZ:AV0Z40400503; CEZ:AV0Z10100521 Keywords : palladium * WOx surfaces * TPD Subject RIV: CF - Physical ; Theoretical Chemistry Impact factor: 4.115, year: 2006

Joining of ceramic Ba_0.5Sr_0.5Co_0.8Fe_0.2O₃ membranes for oxygen production to high temperature alloys

DEFF Research Database (Denmark)

Kiebach, Wolff-Ragnar; Engelbrecht, Kurt; Kwok, Kawai

2016-01-01

/reactivity and their thermal expansion coefficient on the stability of the final joint was evaluated. Leak tight assemblies were obtained only for steels with a thermal expansion coefficient of > 16 [10(-6) K-1] and protective coating. Proof-of-concept oxygen flux measurements up to 830 degrees C were performed......The possibility of joining dense ceramic BCSF tubular membranes to metal alloys using a silver braze was investigated. Four different alloys (Crofer 22 APU (R), Kanthal APM (R), Haynes 214 (R) and EN 1.4841) were considered and the influence of their oxide scale stability...

Pd Alloy Membranes for Hydrogen Separation from Coal-Derived Syngas

National Research Council Canada - National Science Library

Alptekin, Gokhan O; DeVoss, Sarah; Amalfitano, Bob; Way, Douglas; Thoen, Paul; Lusk, Mark

2006-01-01

TDA Research Inc., in collaboration with Colorado School of Mines (CSM) is developing a sulfur and CO-tolerant membrane to produce the clean hydrogen from syngas using Pd membrane films prepared on a variety of supports (e.g...

Green Chemistry Approach for Synthesis of Effective Anticancer Palladium Nanoparticles.

Science.gov (United States)

Gurunathan, Sangiliyandi; Kim, EunSu; Han, Jae Woong; Park, Jung Hyun; Kim, Jin-Hoi

2015-12-15

The purpose of this study was to design and synthesize Palladium nanoparticles (PdNPs) using an environmentally friendly approach and evaluate the in vitro efficacy of PdNPs in human ovarian cancer A2780 cells. Ultraviolet-Visible (UV-Vis) spectroscopy was used to monitor the conversion of Pd(II) ions to Pd(0)NPs. X-ray diffraction (XRD) revealed the crystallinity of the as-synthesized PdNPs and Fourier transform infrared spectroscopy (FTIR) further confirmed the role of the leaf extract of Evolvulus alsinoides as a reducing and stabilizing agent for the synthesis of PdNPs. Dynamic light scattering (DLS) and transmission electron microscopy (TEM) showed that the average size of the NPs was 5 nm. After a 24-h exposure to PdNPs, cell viability and light microscopy assays revealed the dose-dependent toxicity of the PdNPs. Furthermore, the dose-dependent cytotoxicity of the PdNPs was confirmed by lactate dehydrogenase (LDH), increased reactive oxygen species (ROS) generation, activation of PdNPs-induced autophagy, impairment of mitochondrial membrane potential (MMP), enhanced caspase-3 activity, and detection of TUNEL-positive cells. Our study demonstrates a single, simple, dependable and green approach for the synthesis of PdNPs using leaf extracts of Evolvulus alsinoides. Furthermore, the in vitro efficacy of PdNPs in human ovarian cancer cells suggests that it could be an effective therapeutic agent for cancer therapy.

Co-current and Counter-Current Operations for Steam Reforming of Heptane in a Novel CFB Membrane Reformer

International Nuclear Information System (INIS)

Chen, Z.; Elnashaie, S.S.E.H.

2004-01-01

Hydrogen production by steam reforming of higher hydrocarbon over nickel supported catalyst is investigated in an earlier suggested novel Circulating Fast Fluidized Bed Membrane Reformer (CFFBMR). Palladium hydrogen membranes are used with co-current and counter-current operation modes. It is found that hydrogen production has a non-monotonic dependence upon the reaction temperature in the range of 623-823 K. Between 623 and 723 K. the yields of hydrogen decrease and then increase between 723 and 823 K. This important phenomenon is investigated, discussed and explained. The simulation results shows that the reformer performance can be significantly improved using hydrogen membranes, especially in the counter-current operation mode. At low temperatures around 623 K, both .co-current and counter-current operation modes provide similar yields of hydrogen. While at temperature 723 K and higher, the counter-current operation provides the highest yield of hydrogen

Hydrogen storage in thin film magnesium-scandium alloys

International Nuclear Information System (INIS)

Niessen, R.A. H.; Notten, P.H. L.

2005-01-01

Thorough electrochemical materials research has been performed on thin films of novel magnesium-scandium hydrogen storage alloys. It was found that palladium-capped thin films of Mg x Sc (1-x) with different compositions (ranging from x=0.50 -0.90) show an increase in hydrogen storage capacity of more than 5-20% as compared to their bulk equivalents using even higher discharge rates. The maximum reversible hydrogen storage capacity at the optimal composition (Mg 80 Sc 20 ) amounts to 1795-bar mAh/g corresponding to a hydrogen content of 2.05 H/M or 6.7-bar wt.%, which is close to five times that of the commonly used hydride-forming materials in commercial NiMH batteries. Galvanostatic intermittent titration technique (GITT) measurements show that the equilibrium pressure during discharge is lower than that of bulk powders by one order of magnitude (10 -7 -bar mbar versus 10 -6 -bar mbar, respectively)

XPS study of palladium sensitized nano porous silicon thin film

Indian Academy of Sciences (India)

Keywords. Porous silicon; passivation; palladium; oxidation; XPS. Abstract. Nano porous silicon (PS) was formed on -type monocrystalline silicon of 2–5 cm resistivity and (100) orientation by electrochemical anodization method using HF and ethanol as the electrolytes. High density of surface states, arising due to its ...

Electronic structure of palladium and its relation to uv spectroscopy

DEFF Research Database (Denmark)

Christensen, N.E.

1976-01-01

The electronic-energy-band structure of palladium has been calculated by means of the relativistic augmented-plane-wave method covering energies up to 30 eV above the Fermi level. The optical interband transitions producing structure in the dielectric function up to photon energies of 25 eV have ...

Palladium-based on-wafer electroluminescence studies of GaN-based LED structures

Energy Technology Data Exchange (ETDEWEB)

Salcianu, C.O.; Thrush, E.J.; Humphreys, C.J. [Department of Materials Science and Metallurgy, University of Cambridge, Pembroke Street, Cambridge CB2 3QZ (United Kingdom); Plumb, R.G. [Centre for Photonic Systems, Department of Engineering, University of Cambridge, Cambridge CB3 0FD (United Kingdom); Boyd, A.R.; Rockenfeller, O.; Schmitz, D.; Heuken, M. [AIXTRON AG, Kackertstr. 15-17, 52072 Aachen (Germany)

2008-07-01

Electroluminescence (EL) testing of Light Emitting Diode (LED) structures is usually done at the chip level. Assessing the optical and electrical properties of LED structures at the wafer scale prior to their processing would improve the cost effectiveness of producing LED-lamps. A non-destructive method for studying the luminescence properties of the structure at the wafer-scale is photoluminescence (PL). However, the relationship between the on-wafer PL data and the final device EL can be less than straightforward (Y. H Aliyu et al., Meas. Sci. Technol. 8, 437 (1997)) as the two techniques employ different carrier injection mechanisms. This paper provides an overview of some different techniques in which palladium is used as a contact in order to obtain on-wafer electroluminescence information which could be used to screen wafers prior to processing into final devices. Quick mapping of the electrical and optical characteristics was performed using either palladium needle electrodes directly, or using the latter in conjunction with evaporated palladium contacts to inject both electrons and holes into the active region via the p-type capping layer of the structure. For comparison, indium was also used to make contact to the n-layer so that electrons could be directly injected into that layer. (copyright 2008 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

Spatial and temporal distribution of platinum, palladium and rhodium in Zagreb air.

Science.gov (United States)

Rinkovec, Jasmina; Pehnec, Gordana; Godec, Ranka; Davila, Silvije; Bešlić, Ivan

2018-09-15

Platinum (Pt), palladium (Pd) and rhodium (Rh) are most widely used in the production of automotive catalytic converters that serve to reduce toxic emissions from motor vehicles. The aim of this study was to quantitatively determine the levels of platinum, palladium and rhodium in the PM 10 and PM 2.5 fraction of airborne particle matter and find their spatial and temporal distribution at different polluted areas of the city of Zagreb, Croatia. The method used in this paper included weekly sampling of airborne particle matter on quartz filters, microwave digestion in acid under high pressure and temperature, and analysis by inductively coupled plasma mass spectrometry (ICP MS). The results have shown that the highest mean values at all three sampling stations (North, Center, South) were obtained for palladium (3.856 pg m -3 , 5.396 pg m -3 , 5.600 pg m -3 ) and the lowest for rhodium (0.444 pg m -3 , 0.643 pg m -3 , 0.750 pg m -3 ). The average mass concentrations of platinum group elements (PGE) in PM 10 increased for all three elements in the direction North Zagreb are the first results of their kind for this area and will provide insights into the contribution of catalytic converters to the presence of these elements in the environment. Copyright © 2018 Elsevier B.V. All rights reserved.

Nonenzymatic glucose sensing based on deposited palladium nanoparticles on epoxy-silver electrodes

International Nuclear Information System (INIS)

Gutes, Albert; Carraro, Carlo; Maboudian, Roya

2011-01-01

Highlights: → New nonenzymatic glucose sensor material. → Modified epoxy-silver electrodes with palladium nanoparticles. → Simple electroless surface modification. → Wide linear response range. → Easy implementation. - Abstract: A new approach for nonenzymatic glucose sensing, based on a simple modification of epoxy-silver surfaces deposited on the tip of commercial copper electric wires, is presented. Palladium was galvanically displaced on the surface of the epoxy-silver surface in order to obtain metal nanoparticles that act as catalyst for the direct oxidation of glucose. Scanning electron microscopy revealed the formation of the metal nanoparticles. X-ray photoelectron spectroscopy confirmed the metallic nature of the formed nanostructures on the surface. Electrochemical characterization and calibration of the palladium-modified epoxy-silver electrode is reported, obtaining a linear range of 1-20 mM for the detection of glucose with low interference of ascorbic acid and uric acid. A simple 3-step coulometry was used as the detection technique. The developed sensing material is believed to be a great candidate for integration in small devices for clinical essays, due to the simplicity and cost effectiveness of the presented approach, compared to the state-of-the-art devices reported recently in the literature. Simplicity in the coulometry determinations makes these Pd-modified epoxy-silver sensors a good candidate for easy glucose determinations.

Biosorption of platinum and palladium for their separation/preconcentration prior to graphite furnace atomic absorption spectrometric determination

Energy Technology Data Exchange (ETDEWEB)

Godlewska-Zylkiewicz, Beata E-mail: bgodlew@uwb.edu.pl

2003-08-15

Inexpensive baker's yeast Saccharomyces cerevisiae and green algae Chlorella vulgaris, either free or immobilized on silica gel have been shown to selectively accumulate platinum and palladium from water samples in acidic medium (pH 1.6-1.8). Optimization of conditions of metals biosorption (sample pH, algae and yeast masses, adsorption time, temperature) was performed in batch mode. The procedure of matrix separation based on biosorption of platinum and palladium on algae C. vulgaris covalently immobilized on silica gel in flow mode was developed. The use of algae in flow procedure offers several advantages compared with its use in the batch mode. The procedure shows better reproducibility (<2%), improved efficiency of platinum retention on the column (93.3{+-}1.6%), is less laborious and less time consuming. The best recovery of biosorbed metals from column (87.7{+-}3.3% for platinum and 96.8{+-}1.1 for palladium) was obtained with solution of 0.3 mol l{sup -1} thiourea in 1 mol l{sup -1} hydrochloric acid. The influence of thiourea on analytical signals of examined metals during GFAAS determination is discussed. The procedure has been applied for separation of noble metals from tap and waste water samples spiked with platinum and palladium.

Microstructured Electrolyte Membranes to Improve Fuel Cell Performance

Science.gov (United States)

Wei, Xue

reactant type, reagent concentration, solution pH, and reaction time. Dense apatite films were formed on palladium substrates that can serve as intermediate temperature fuel cell anodes. The novel apatite membrane structure is promising for fuel cell applications, as well as in improving the biocompatibility of orthopedic implants when coated on stainless steel or titanium substrates.

Catalytic Palladium Film Deposited by Scalable Low-Temperature Aqueous Combustion.

Science.gov (United States)

Voskanyan, Albert A; Li, Chi-Ying Vanessa; Chan, Kwong-Yu

2017-09-27

This article describes a novel method for depositing a dense, high quality palladium thin film via a one-step aqueous combustion process which can be easily scaled up. Film deposition of Pd from aqueous solutions by conventional chemical or electrochemical methods is inhibited by hydrogen embrittlement, thus resulting in a brittle palladium film. The method outlined in this work allows a direct aqueous solution deposition of a mirror-bright, durable Pd film on substrates including glass and glassy carbon. This simple procedure has many advantages including a very high deposition rate (>10 cm 2 min -1 ) and a relatively low deposition temperature (250 °C), which makes it suitable for large-scale industrial applications. Although preparation of various high-quality oxide films has been successfully accomplished via solution combustion synthesis (SCS) before, this article presents the first report on direct SCS production of a metallic film. The mechanism of Pd film formation is discussed with the identification of a complex formed between palladium nitrate and glycine at low temperature. The catalytic properties and stability of films are successfully tested in alcohol electrooxidation and electrochemical oxygen reduction reaction. It was observed that combustion deposited Pd film on a glassy carbon electrode showed excellent catalytic activity in ethanol oxidation without using any binder or additive. We also report for the first time the concept of a reusable "catalytic flask" as illustrated by the Suzuki-Miyaura cross-coupling reaction. The Pd film uniformly covers the inner walls of the flask and eliminates the catalyst separation step. We believe the innovative concept of a reusable catalytic flask is very promising and has the required features to become a commercial product in the future.

Studies on nickel (II and palladium (II complexes with some tetraazamacrocycles containing tellurium

Directory of Open Access Journals (Sweden)

Rathee Nitu

2012-01-01

Full Text Available The synthesis of 10-membered and 12-membered tellurium containing tetraazamacrocyclic complexes of divalent nickel and palladium by template condensation of diaryltellurium dichlorides, (aryl = p-hydroxyphenyl, 3-methyl-4-hydroxyphenyl, p-methoxyphenyl with 1,2-diaminoethane and 1,3-diaminopropane in the presence of metal dichloride is reported. The resulting complexes have been subjected to elemental analyses, magnetic measurements, electronic absorption, infra-red, and proton magnetic resonance spectral studies. The formation of proposed macrocyclic skeletons and their donor sites have been identified on the basis of spectral studies. Distorted octahedral structure for the nickel complexes in the solid state and squareplanar structure for the palladium complexes have been suggested.

Moessbauer study of the amorphous Pd70Fe10Si20 alloy upon transition to the crystalline state

International Nuclear Information System (INIS)

Sitek, J.; Prejsa, M.; Cirak, J.; Hucl, M.; Lipka, J.

1978-01-01

Foils of the amorphous alloy Pd 70 Fe 10 Si 20 were investigated after isothermal heating at the temperature range 350-450 0 C with a heating period from 15 min to 4 h. At 350 0 C no changes were observed in the shape of the Moessbauer spectra. At 400 0 C and at 450 0 C up to 30 min only the parameters of Moessbauer spectra consisting of two quadrupole doublets corresponding to palladium and silicon vicinities of iron atoms were changed. After further heating at 450 0 C crystalline phases of Pd 3 Fe and Fe 3 Si appeared on the Moessbauer spectra. (Auth.)

Low-temperature solution processing of palladium/palladium oxide films and their pH sensing performance.

Science.gov (United States)

Qin, Yiheng; Alam, Arif U; Pan, Si; Howlader, Matiar M R; Ghosh, Raja; Selvaganapathy, P Ravi; Wu, Yiliang; Deen, M Jamal

2016-01-01

Highly sensitive, easy-to-fabricate, and low-cost pH sensors with small dimensions are required to monitor human bodily fluids, drinking water quality and chemical/biological processes. In this study, a low-temperature, solution-based process is developed to prepare palladium/palladium oxide (Pd/PdO) thin films for pH sensing. A precursor solution for Pd is spin coated onto pre-cleaned glass substrates and annealed at low temperature to generate Pd and PdO. The percentages of PdO at the surface and in the bulk of the electrodes are correlated to their sensing performance, which was studied by using the X-ray photoelectron spectroscope. Large amounts of PdO introduced by prolonged annealing improve the electrode's sensitivity and long-term stability. Atomic force microscopy study showed that the low-temperature annealing results in a smooth electrode surface, which contributes to a fast response. Nano-voids at the electrode surfaces were observed by scanning electron microscope, indicating a reason for the long-term degradation of the pH sensitivity. Using the optimized annealing parameters of 200°C for 48 h, a linear pH response with sensitivity of 64.71±0.56 mV/pH is obtained for pH between 2 and 12. These electrodes show a response time shorter than 18 s, hysteresis less than 8 mV and stability over 60 days. High reproducibility in the sensing performance is achieved. This low-temperature solution-processed sensing electrode shows the potential for the development of pH sensing systems on flexible substrates over a large area at low cost without using vacuum equipment. Copyright © 2015 Elsevier B.V. All rights reserved.

Selective extraction of palladium with caffeine from acidic chloride media; Sansei enkabutsu yoeki karano kafuein ni yoru parajiumu no sentakuteki chushutsu

Energy Technology Data Exchange (ETDEWEB)

Kaikake, K.; Baba, Y. [Miyazaki University, Miyazaki (Japan). Faculty of Engineering

1999-06-10

In order to examine the possibility of caffeine as an extractant, the extraction of metal ions from acidic chloride media was studied at 298 K using the mixture solvent of chloroform and 2-ethyl-1-hexanol. Caffeine has exhibited a high selectivity for palladium (2) over base metals such as copper (2), nickel (2), and iron (3), and over precious metal such as platinum (4). The stoichiometric relation in the extraction of palladium (2) with caffeine was elucidated by examining the effects of chloride ion, hydrogen ion, and caffeine concentrations on its extractability. In addition, palladium (2) was found to be extracted selectively with caffeine from the mixture containing a 25-fold amount of platinum (4) or copper (2). The stripping of palladium (2) was performed to an extent of 80% by a single batchwise treatment with an aqueous mixture solution of hydrochloric acid and thiourea. (author)

Practical, economical, and eco-friendly starch-supported palladium catalyst for Suzuki coupling reactions.

Science.gov (United States)

Baran, Talat

2017-06-15

In catalytic systems, the support materials need to be both eco friendly and low cost as well as having high thermal and chemical stability. In this paper, a novel starch supported palladium catalyst, which had these outstanding properties, was designed and its catalytic activity was evaluated in a Suzuki coupling reaction under microwave heating with solvent-free and mild reaction conditions. The starch supported catalyst gave remarkable reaction yields after only 5min as a result of the coupling reaction of the phenyl boronic acid with 23 different substrates, which are bearing aril bromide, iodide, and chloride. The longevity of the catalyst was also investigated, and the catalyst could be reused for 10 runs. The starch supported Pd(II) catalyst yielded remarkable TON (up to 25,000) and TOF (up to 312,500) values by using a simple, fast and eco-friendly method. In addition, the catalytic performance of the catalyst was tested against different commercial palladium catalysts, and the green starch supported catalyst had excellent selectivity. The catalytic tests showed that the novel starch based palladium catalyst proved to be an economical and practical catalyst for the synthesis of biaryl compounds. Copyright © 2017 Elsevier Inc. All rights reserved.

Thermochemical Properties of Group IVB and VB Transition Metal Alloys with Platinum Group Metals: Acid - Stabilization.

Science.gov (United States)

Cima, Michael John

Solid-state galvanic cell measurements and oxide equilibration experiments are used to derive thermochemical quantities for a variety of acid-base stabilized alloys such as Nb-Pd, Nb-Rh, Ti-Pd, and Ti-Rh. The experiments have effectively resulted in the titration of palladium by niobium metal. The excess partial molar Gibbs energy of niobium at infinite dilution was determined to be -62 kcal/mole at 1000^circ C and the Gibbs energy of formation of {rm NbPd}_{3.55} is -42 kcal/mole. These results and those for the other systems are used to assess the importance of crystal field effects in the context of the generalized Lewis acid-base theory.

Chalcogen-containing oxazolines in the palladium-catalyzed asymmetric allylic alkylation

Directory of Open Access Journals (Sweden)

Braga Antonio L.

2006-01-01

Full Text Available A comparative study about the ability of chiral chalcogen-containing oxazolines to act as chiral ligands in the palladium-catalyzed allylic alkylation of rac-1,3-diphenyl-2-propenyl acetate with dimethyl malonate is reported. Differences in the catalytic performance are observed with sulfur, selenium and tellurium analogues.

Supporting Information Palladium Complexes of a New Type of N ...

Indian Academy of Sciences (India)

Prasenjit Ghosh

Palladium Complexes of a New Type of N-heterocyclic Carbene. Ligand Derived From a Tricyclic Triazolooxazine Framework. Manoj Kumar Gangwar, Alok Ch. Kalita and Prasenjit Ghosh*. Department of Chemistry,. Indian Institute of Technology Bombay, ... 2. Figure S1. 1. H NMR spectrum of the compound 1a in CDCl3.

Size control and supporting of palladium nanoparticles made by laser ablation in saline solution as a facile route to heterogeneous catalysts

International Nuclear Information System (INIS)

Marzun, Galina; Nakamura, Junji; Zhang, Xiaorui; Barcikowski, Stephan; Wagener, Philipp

2015-01-01

Graphical abstract: - Highlights: • We studied laser-generated, size-controlled palladium nanoparticles in saline solution. • Palladium nanoparticles were electrostatically stabilized by anions. • Photo- and electrocatalyst are prepared by supporting Pd nanoparticles to TiO 2 and graphene. • Particle size does not change during supporting process, while 18 wt% load has been achieved. • Palladium nanoparticles and graphene undergo a redox-reaction during adsorption. - Abstract: In the literature many investigations on colloidal stability and size control of gold nanoparticles are shown but less for ligand-free palladium nanoparticles, which can be promising materials in various applications. Palladium nanoparticles are perspective materials for a manifold of energy application like photo- and electrocatalysis or hydrogen storage. For this purpose, size-controlled nanoparticles with clean surfaces and facile immobilization on catalyst supports are wanted. Laser ablation in saline solution yields ligand-free, charged colloidal palladium nanoparticles that are supported by titania and graphene nanosheets as model systems for photo- and electrocatalysis, respectively. By adjusting the ionic strength during laser ablation in liquid, it is possible to control stability and particle size without compromising subsequent nanoparticle adsorption of supporting materials. A quantitative deposition of nearly 100% yield with up to 18 wt% nanoparticle load was achieved. The average size of the laser-generated nanoparticles remains the same after immobilization on a support material, in contrast to other preparation methods of catalysts. The characterization by X-ray photoelectron spectroscopy reveals a redox reaction between the immobilized nanoparticles and the graphene support

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.

Membrane Purification Cell for Aluminum Recycling

Energy Technology Data Exchange (ETDEWEB)

David DeYoung; James Wiswall; Cong Wang

2011-11-29

Recycling mixed aluminum scrap usually requires adding primary aluminum to the scrap stream as a diluent to reduce the concentration of non-aluminum constituents used in aluminum alloys. Since primary aluminum production requires approximately 10 times more energy than melting scrap, the bulk of the energy and carbon dioxide emissions for recycling are associated with using primary aluminum as a diluent. Eliminating the need for using primary aluminum as a diluent would dramatically reduce energy requirements, decrease carbon dioxide emissions, and increase scrap utilization in recycling. Electrorefining can be used to extract pure aluminum from mixed scrap. Some example applications include producing primary grade aluminum from specific scrap streams such as consumer packaging and mixed alloy saw chips, and recycling multi-alloy products such as brazing sheet. Electrorefining can also be used to extract valuable alloying elements such as Li from Al-Li mixed scrap. This project was aimed at developing an electrorefining process for purifying aluminum to reduce energy consumption and emissions by 75% compared to conventional technology. An electrolytic molten aluminum purification process, utilizing a horizontal membrane cell anode, was designed, constructed, operated and validated. The electrorefining technology could also be used to produce ultra-high purity aluminum for advanced materials applications. The technical objectives for this project were to: - Validate the membrane cell concept with a lab-scale electrorefining cell; - Determine if previously identified voltage increase issue for chloride electrolytes holds for a fluoride-based electrolyte system; - Assess the probability that voltage change issues can be solved; and - Conduct a market and economic analysis to assess commercial feasibility. The process was tested using three different binary alloy compositions (Al-2.0 wt.% Cu, Al-4.7 wt.% Si, Al-0.6 wt.% Fe) and a brazing sheet scrap composition (Al-2

Synthesis of heterocyclic compounds through palladium-catalyzed C-H cyclization processes.

Science.gov (United States)

Inamoto, Kiyofumi

2013-01-01

Herein, we describe our development of synthetic methods for heterocyclic compounds based on the palladium-catalyzed carbon-hydrogen bond (C-H) functionalization/intramolecular carbon-heteroatom (nitrogen or sulfur) bond formation process. By this C-H cyclization method, we efficiently prepared various N-heterocycles, including indazoles, indoles, and 2-quinolinones, as well as S-heterocycles such as benzothiazoles and benzo[b]thiophenes. Yields are typically good to high and good functional-group tolerance is observed for each process, thereby indicating that the method provides a novel, highly applicable synthetic route to the abovementioned biologically important heterocyclic frameworks. As an application of this approach, an auto-tandem-type, one-pot process involving the oxidative Heck reaction and subsequent C-H cyclization using cinnamamides and arylboronic acids as starting materials in the presence of a palladium catalyst was also developed for the rapid construction of the 2-quinolinone nucleus.

Palladium-Catalyzed alpha-Arylation of Tetramic Acids

DEFF Research Database (Denmark)

Storgaard, Morten; Dorwald, F. Z.; Peschke, B.

2009-01-01

A mild, racemization-free, palladium-Catalyzed alpha-arylation of tetramic acids (2,4-pyrrolidinediones) has been developed. Various amino acid-derived tetramic acids were cleanly arylated by treatment with 2 mol % of Pd(OAc)(2), 4 mol % of a sterically demanding biaryl phosphine, 2.3 equiv of K2CO...... no effect on their reactivity: both electron-rich and electron-poor aryl chlorides and bromides or triflates led to good yields. Ortho-substituted aryl halides and heteroaryl halides, however, did not undergo the title reaction....

Synthesis of Dihydrobenzofurans via Palladium-Catalyzed Heteroannulations

Energy Technology Data Exchange (ETDEWEB)

Rozhkov, Roman Vladimirovich [Iowa State Univ., Ames, IA (United States)

2004-01-01

Palladium-catalyzed heteroannulation of 1,3-dienes with 3-iodo-2-alkenols, and 2-iodo-2-alkenols, as well as their amino analogs, affords the corresponding cyclic ethers and amines respectively. The presence of a β-hydrogen in the vinylic halide results in β-hydride elimination giving the corresponding alkyne. The presence of a bulky group in the α-position of the vinylic halide results in failure or reduced amounts of annulation products. A chloride source, pyridine base and electron-rich phosphine are essential for this reaction.

A tandem Mannich addition–palladium catalyzed ring-closing route toward 4-substituted-3(2H-furanones

Directory of Open Access Journals (Sweden)

Jubi John

2014-06-01

Full Text Available A facile route towards highly functionalized 3(2H-furanones via a sequential Mannich addition–palladium catalyzed ring closing has been elaborated. The reaction of 4-chloroacetoacetate esters with imines derived from aliphatic and aromatic aldehydes under palladium catalysis afforded 4-substituted furanones in good to excellent yields. 4-Hydrazino-3(2H-furanones could also be synthesized from diazo esters in excellent yields by utilising the developed strategy. We could also efficiently transform the substituted furanones to aza-prostaglandin analogues.

Syngas upgrading in a membrane reactor with thin Pd-alloy supported membrane

NARCIS (Netherlands)

Brunetti, A.; Caravella, A.; Fernandez Gesalaga, E.; Pacheco Tanaka, D. A.; Gallucci, F.; Drioli, E.; Curcio, E.; Viviente, J. L.; Barbieri, G.

2015-01-01

In hydrogen production, the syngas streams produced by reformers and/or coal gasification plants contain a large amount of H2 and CO in need of upgrading. To this purpose, reactors using Pd-based membranes have been widely studied as they allow separation and recovery of a pure hydrogen stream.

Electrothermal atomic absorption spectrometric determination of copper in nickel-base alloys with various chemical modifiers*1

Science.gov (United States)

Tsai, Suh-Jen Jane; Shiue, Chia-Chann; Chang, Shiow-Ing

1997-07-01

The analytical characteristics of copper in nickel-base alloys have been investigated with electrothermal atomic absorption spectrometry. Deuterium background correction was employed. The effects of various chemical modifiers on the analysis of copper were investigated. Organic modifiers which included 2-(5-bromo-2-pyridylazo)-5-(diethylamino-phenol) (Br-PADAP), ammonium citrate, 1-(2-pyridylazo)-naphthol, 4-(2-pyridylazo)resorcinol, ethylenediaminetetraacetic acid and Triton X-100 were studied. Inorganic modifiers palladium nitrate, magnesium nitrate, aluminum chloride, ammonium dihydrogen phosphate, hydrogen peroxide and potassium nitrate were also applied in this work. In addition, zirconium hydroxide and ammonium hydroxide precipitation methods have also been studied. Interference effects were effectively reduced with Br-PADAP modifier. Aqueous standards were used to construct the calibration curves. The detection limit was 1.9 pg. Standard reference materials of nickel-base alloys were used to evaluate the accuracy of the proposed method. The copper contents determined with the proposed method agreed closely with the certified values of the reference materials. The recoveries were within the range 90-100% with relative standard deviation of less than 10%. Good precision was obtained.

Catalytic Enantioselective Alkylation of β-Keto Esters with Xanthydrol in the Presence of Chiral Palladium Complex

Energy Technology Data Exchange (ETDEWEB)

Kim, Kyu Yeon; Kim, Dae Young [Soonchunhyang Univ., Asan (Korea, Republic of)

2016-01-15

Our research interest has been directed toward the development of synthetic methods for the enantioselective construction of stereogenic carbon centers. Recently, we explored the catalytic enantioselective functionalization of active methines in the presence of chiral palladium(II) complexes. In conclusion, we have accomplished the efficient catalytic enantioselective alkylation of β-keto esters 1 with xanthydrol 2 with high yields and excellent enantioselectivity (up to 98% ee). It should be noted that this alkyaltion reaction proceeds well using air- and moisture-stable chiral palladium com- plexes with low loading (1 mol%)

PVP-Stabilized Palladium Nanoparticles in Silica as Effective Catalysts for Hydrogenation Reactions

Directory of Open Access Journals (Sweden)

Caroline Pires Ruas

2013-01-01

Full Text Available Palladium nanoparticles stabilized by poly (N-vinyl-2-pyrrolidone (PVP can be synthesized by corresponding Pd(acac2 (acac = acetylacetonate as precursor in methanol at 80°C for 2 h followed by reduction with NaBH4 and immobilized onto SiO2 prepared by sol-gel process under acidic conditions (HF or HCl. The PVP/Pd molar ratio is set to 6. The effect of the sol-gel catalyst on the silica morphology and texture and on Pd(0 content was investigated. The catalysts prepared (ca. 2% Pd(0/SiO2/HF and ca. 0,3% Pd(0/SiO2/HCl were characterized by TEM, FAAS, and SEM-EDS. Palladium nanoparticles supported in silica with a size 6.6 ± 1.4 nm were obtained. The catalytic activity was tested in hydrogenation of alkenes.

Preparation of fluorinated biaryls through direct palladium-catalyzed coupling of polyfluoroarenes with aryltrifluoroborates

KAUST Repository

Fang, Xin; Huang, Yuanyuan; Chen, Xiaoqing; Lin, Xiaoxi; Bai, Zhengshuai; Huang, Kuo-Wei; Yuan, Yaofeng; Weng, Zhiqiang

2013-01-01

The direct palladium-catalyzed coupling of polyfluoroarenes with aryltrifluoroborates gave the desired products of fluorinated biaryls in good to excellent yields. A diverse set of important functional groups including methoxy, aldehyde, ester

Highly sensitive glucose sensor based on monodisperse palladium nickel/activated carbon nanocomposites.

Science.gov (United States)

Koskun, Yağmur; Şavk, Aysun; Şen, Betül; Şen, Fatih

2018-06-20

Glucose enzyme biosensors have been used for a variety of applications such as medical diagnosis, bioprocess engineering, beverage industry and environmental scanning etc. and there is still a growing interest in glucose sensors. For this purpose, addressed herein, as a novel glucose sensor, highly sensitive activated carbon (AC) decorated monodisperse nickel and palladium alloy nanocomposites modified glassy carbon electrode (Ni-Pd@AC/GCE NCs) have been synthesized by in-situ reduction technique. Raman Spectroscopy (RS), X-ray Photoelectron Spectroscopy (XPS), X-ray Diffraction (XRD), Transmission Electron Microscopy (TEM), cyclic voltammetry (CV) and chronoamperometry (CA) were used for the characterization of the prepared non-enzymatic glucose sensor. The characteristic sensor properties of the Ni-Pd@AC/GCE electrode were compared with Ni-Pd NCs/GCE, Ni@AC/GCE and Pd@AC/GCE and the results demonstrate that the AC is very effective in the enhancement of the electrocatalytic properties of sensor. In addition, the Ni-Pd@AC/GCE nanocomposites showed a very low detection limit of 0.014 μM, a wide linear range of 0.01 mM-1 mM and a very high sensitivity of 90 mA mM -1  cm -2 . Furthermore, the recommended sensor offer the various advantageous such as facile preparation, fast response time, high selectivity and sensitivity. Lastly, monodisperse Ni-Pd@AC/GCE was utilized to detect glucose in real sample species. Copyright © 2018 Elsevier B.V. All rights reserved.

Mechanism of reductive elimination. Reaction of alkylpalladium(II) complexes with tetraorganotin, organolithium, and Grignard reagents. Evidence for palladium(IV) intermediacy

International Nuclear Information System (INIS)

Milstein, D.; Stille, J.K.

1979-01-01

Coupling products are obtained in good yields from the reaction of tetraorganotin compounds or Grignard reagents and organohalogenopalladium(II) complexes provided that a benzyl bromide is present. Low yields are obtained in the absence of the benzyl bromides, in which case other decomposition pathways (e.g., α elimination) take place, even in the presence of electron acceptors (e.g., oxygen, m-dinitrobenzene). The first step in the reaction of benzylhalogenobis(triphenylphosphine)-palladium(II) complexes with MeM (M = SnMe 3 , MgBr) is metathesis of the benzyl ligand rather than the halogen. This unique carbon-for-carbon transmetalation takes place at 25 0 C and is facilitated by electron-donating substituents on the benzyl ligand. The products of this reaction subsequently react at higher temperature in the presence of a benzyl bromide to afford ethylbenzene. Optically active chloro-(α-deuteriobenzyl)bis(triphenylphosphine)palladium yields, upon reaction with tetramethyltin in the presence of p-nitrobenzyl bromide, optically active α-deuterioethylbenzene in which overall retention of configuration at carbon has resulted. cis-dimethylbis(triphenylphosphine)palladium(II) reacts with benzyl bromide at 25 0 C to afford ethylbenzene and bromomethylbis(triphenylphosphine)palladium(II) rather than ethane. When optically active α-deuteriobenzyl bromide is used in this reaction, optically active α-deuterioethylbenzene is formed, and inversion of configuration at carbon takes place. The reductive elimination process is proposed to take place preferentially from a palladium(IV) intermediate with retention of configuration at carbon

Electrooxidation of aliphatic alcohols on palladium oxide catalyst prepared by pulsed electrodeposition technique

International Nuclear Information System (INIS)

Casella, Innocenzo G.

2009-01-01

Palladium film can be deposited on gold polycrystalline electrodes, from a deoxygenated alkaline solution containing 50 mM NaOH plus 0.5 mM K 2 Pd(CN) 4 . A multipulse sequence of potentials of equal amplitude and duration was used for the palladium deposition process. In particular, an optimized waveform of potentials of E 1 = 1.0 V vs. SCE and E 2 = -1.0 V vs. SCE for the relevant pulse duration of t 1 = 0.05 s and t 2 = 0.05 s, for 30 s, was used. Cyclic voltammetry and scanning electron microscopy (SEM) were employed to characterize the gold-palladium modified electrode (Au-Pd) towards the electrooxidation of aliphatic alcohols in alkaline solutions. The voltammetric study suggests that the kinetics involved in the alcohol electrooxidation at the Pd-Au electrode are sensibly higher than those observed on the bare Pd and Au electrodes. In addition, the most interesting aspect of the electrooxidation of aliphatic alcohols at the Au-Pd electrode was that as the number of methylene groups on the homologous series of aliphatic alcohols increased, the molar response also increased. Under pulsed chronoamerometric conditions (PCC), using an optimized triple pulse waveform of potentials the modified electrode exhibits interesting catalytic currents without any apparent poisoning effects during the oxidation of aliphatic alcohols.

On the possibility of deuteron disintegration in electrochemically compressed D+ in a palladium cathode

International Nuclear Information System (INIS)

Ragheb, M.; Miley, G.H.

1989-01-01

The possibility of deuteron disintegration due to polarization in the coulomb field of a target nucleus according to an Oppenheimer-Phillips process is discussed within the context of electrochemically compressed D + in a palladium cathode. This reaction is possible between deuterons and palladium isotopes, as well as between the deuterons themselves. In the last case, the equivalent of the proton branch of the deuterium-deuterium fusion reaction occurs in preference to the neutron branch. The process provides a possible explanation for the observed energy release, tritium production, and neutron suppression in the Fleischmann and Pons experiment. If such a process can be experimentally verified, analogous processes leading to the disintegration of the 9 Be nucleus may be achievable

Catalytic wet oxidation of ammonia solution: Activity of the nanoscale platinum-palladium-rhodium composite oxide catalyst

International Nuclear Information System (INIS)

Hung, C.-M.

2009-01-01

Aqueous solutions of 400-1000 mg/L of ammonia were oxidized in a trickle-bed reactor (TBR) in this study of nanoscale platinum-palladium-rhodium composite oxide catalysts, which were prepared by the co-precipitation of H 2 PtCl 6 , Pd(NO 3 ) 3 and Rh(NO 3 ) 3 . Hardly any of the dissolved ammonia was removed by wet oxidation in the absence of any catalyst, whereas about 99% of the ammonia was reduced during wet oxidation over nanoscale platinum-palladium-rhodium composite oxide catalysts at 503 K in an oxygen partial pressure of 2.0 MPa. A synergistic effect exists in the nanoscale platinum-palladium-rhodium composite structure, which is the material with the highest ammonia reduction activity. The nanometer-sized particles were characterized by TEM, XRD and FTIR. The effect of the initial concentration and reaction temperature on the removal of ammonia from the effluent streams was also studied at a liquid hourly space velocity of under 9 h -1 in the wet catalytic processes

Catalytic wet oxidation of ammonia solution: Activity of the nanoscale platinum-palladium-rhodium composite oxide catalyst

Energy Technology Data Exchange (ETDEWEB)

Hung, C.-M. [Department of Industry Engineering and Management, Yung-Ta Institute of Technology and Commerce, 316 Chung-shan Road, Linlo, Pingtung 909, Taiwan (China)], E-mail: hungcm1031@gmail.com

2009-04-15

Aqueous solutions of 400-1000 mg/L of ammonia were oxidized in a trickle-bed reactor (TBR) in this study of nanoscale platinum-palladium-rhodium composite oxide catalysts, which were prepared by the co-precipitation of H{sub 2}PtCl{sub 6}, Pd(NO{sub 3}){sub 3} and Rh(NO{sub 3}){sub 3}. Hardly any of the dissolved ammonia was removed by wet oxidation in the absence of any catalyst, whereas about 99% of the ammonia was reduced during wet oxidation over nanoscale platinum-palladium-rhodium composite oxide catalysts at 503 K in an oxygen partial pressure of 2.0 MPa. A synergistic effect exists in the nanoscale platinum-palladium-rhodium composite structure, which is the material with the highest ammonia reduction activity. The nanometer-sized particles were characterized by TEM, XRD and FTIR. The effect of the initial concentration and reaction temperature on the removal of ammonia from the effluent streams was also studied at a liquid hourly space velocity of under 9 h{sup -1} in the wet catalytic processes.

Catalytic wet oxidation of ammonia solution: activity of the nanoscale platinum-palladium-rhodium composite oxide catalyst.

Science.gov (United States)

Hung, Chang-Mao

2009-04-15

Aqueous solutions of 400-1000 mg/L of ammonia were oxidized in a trickle-bed reactor (TBR) in this study of nanoscale platinum-palladium-rhodium composite oxide catalysts, which were prepared by the co-precipitation of H(2)PtCl(6), Pd(NO(3))(3) and Rh(NO(3))(3). Hardly any of the dissolved ammonia was removed by wet oxidation in the absence of any catalyst, whereas about 99% of the ammonia was reduced during wet oxidation over nanoscale platinum-palladium-rhodium composite oxide catalysts at 503 K in an oxygen partial pressure of 2.0 MPa. A synergistic effect exists in the nanoscale platinum-palladium-rhodium composite structure, which is the material with the highest ammonia reduction activity. The nanometer-sized particles were characterized by TEM, XRD and FTIR. The effect of the initial concentration and reaction temperature on the removal of ammonia from the effluent streams was also studied at a liquid hourly space velocity of under 9 h(-1) in the wet catalytic processes.

Interaction of 2-aminopyrimidine with dichloro-[1-alkyl-2-(naphthylazo imidazole]palladium(II complexes : Kinetic and mechanistic studies

Directory of Open Access Journals (Sweden)

Saha Sushanta

2007-10-01

Full Text Available Abstract Background The anticancer properties of cisplatin and palladium(II complexes stem from the ability of the cis-MCl2 fragment to bind to DNA bases. However, cisplatin also interacts with non-cancer cells, mainly through bonding molecules containing -SH groups, resulting in nephrotoxicity. This has aroused interest in the design of palladium(II complexes of improved activity and lower toxicity. The reaction of DNA bases with palladium(II complexes with chelating N,N/donors of the cis-MCl2 configuration constitutes a model system that may help explore the mechanism of cisplatin's anticancer activity. Heterocyclic compounds are found widely in nature and are essential to many biochemical processes. Amongst these naturally occurring compounds, the most thoroughly studied is that of pyrimidine. This was one of the factors that encouraged this study into the kinetics and mechanism of the interaction of 2-aminopyrimidine (2-NH2-Pym with dichloro-{1-alkyl-2-(α-naphthylazoimidazole}palladium(II [Pd(α-NaiRCl2, 1] and dichloro-{1-alkyl-2-(β-naphthylazoimidazole}palladium(II [Pd(β-NaiRCl2, 2] complexes where the alkyl R = Me (a, Et (b, or Bz (c. Results 2-NH2-Pym reacts with 1a, 1b, and 1c to yield [{1-alkyl-2-(α-naphthylazoimidazole}bis(2-aminopyrimidine]palladium(II (3a, 3b, 3c dichloride and with 2a, 2b, and 2c to yield [{1-alkyl-2-(β-naphthylazoimidazole}bis(2-aminopyrimidine]palladium(II (4a, 4b, 4c dichloride in an acetonitrile (MeCN medium. The products were characterized using spectroscopic techniques (FT-IR, UV-Vis, NMR. The ligand substitution reactions follow second order kinetics – first order dependence on the concentration of the Pd(II complex and 2-NH2-Pym. Addition of LiCl to the reaction does not influence its rate. The thermodynamic parameters (standard enthalpy of activation, Δ‡H° and standard entropy of activation, Δ‡S° were determined from variable temperature kinetic studies. The magnitude of the second order

Dechlorination of Environmental Contaminants Using a Hybrid Nanocatalyst: Palladium Nanoparticles Supported on Hierarchical Carbon Nanostructures

Directory of Open Access Journals (Sweden)

Hema Vijwani

2012-01-01

Full Text Available This paper demonstrates the effectiveness of a new type of hybrid nanocatalyst material that combines the high surface area of nanoparticles and nanotubes with the structural robustness and ease of handling larger supports. The hybrid material is made by fabricating palladium nanoparticles on two types of carbon supports: as-received microcellular foam (Foam and foam with carbon nanotubes anchored on the pore walls (CNT/Foam. Catalytic reductive dechlorination of carbon tetrachloride with these materials has been investigated using gas chromatography. It is seen that while both palladium-functionalized carbon supports are highly effective in the degradation of carbon tetrachloride, the rate of degradation is significantly increased with palladium on CNT/Foam. However, there is scope to increase this rate further if the wettability of these structures can be enhanced in the future. Microstructural and spectroscopic analyses of the fresh and used catalysts have been compared which indicates that there is no change in density or surface chemical states of the catalyst after prolonged use in dechlorination test. This implies that these materials can be used repeatedly and hence provide a simple, powerful, and cost-effective approach for dechlorination of water.

Green Chemistry Approach for Synthesis of Effective Anticancer Palladium Nanoparticles

Directory of Open Access Journals (Sweden)

Sangiliyandi Gurunathan

2015-12-01

Full Text Available The purpose of this study was to design and synthesize Palladium nanoparticles (PdNPs using an environmentally friendly approach and evaluate the in vitro efficacy of PdNPs in human ovarian cancer A2780 cells. Ultraviolet-Visible (UV-Vis spectroscopy was used to monitor the conversion of Pd(II ions to Pd(0NPs. X-ray diffraction (XRD revealed the crystallinity of the as-synthesized PdNPs and Fourier transform infrared spectroscopy (FTIR further confirmed the role of the leaf extract of Evolvulus alsinoides as a reducing and stabilizing agent for the synthesis of PdNPs. Dynamic light scattering (DLS and transmission electron microscopy (TEM showed that the average size of the NPs was 5 nm. After a 24-h exposure to PdNPs, cell viability and light microscopy assays revealed the dose-dependent toxicity of the PdNPs. Furthermore, the dose-dependent cytotoxicity of the PdNPs was confirmed by lactate dehydrogenase (LDH, increased reactive oxygen species (ROS generation, activation of PdNPs-induced autophagy, impairment of mitochondrial membrane potential (MMP, enhanced caspase-3 activity, and detection of TUNEL-positive cells. Our study demonstrates a single, simple, dependable and green approach for the synthesis of PdNPs using leaf extracts of Evolvulus alsinoides. Furthermore, the in vitro efficacy of PdNPs in human ovarian cancer cells suggests that it could be an effective therapeutic agent for cancer therapy.

Bulletin of Materials Science | Indian Academy of Sciences

Indian Academy of Sciences (India)

Study of microstructure in vanadium–palladium alloys by X-ray diffraction technique ... cubic (bcc) V–Pd alloys having four different nominal compositions in wt. ... Influence of additives on electrodeposition of bright Zn–Ni alloy on mild steel ..... Effect of size of copper nanoparticles on its catalytic behaviour in Ullman reaction.

Immobilization of Highly Effective Palladium Catalyst onto Poly(4-Vinylpyridine): Synthesis and Characterization

International Nuclear Information System (INIS)

Siti Kamilah Che Soh; Intan Shafinass Kassim; Siti Aminah Jusoh; Mustaffa Samsuddin

2016-01-01

A commonly known weakness of homogeneous catalysts is the difficulty to recover the active catalyst from the product. Due to the disadvantage, the designing of supported catalyst has been approached to overcome the separation difficulty of the palladium-based homogeneous catalyst. New polymer supported N 2 O 2 metal complex was successfully immobilized by mixing of poly(4-vinylpyridine) with palladium(II) complex in the presence of ethyl acetate as solvent. Then, the reaction was stirred for 72 hours at room temperature to form corresponding P 4 VP-Pd catalyst. The properties of immobilized catalyst were characterized by various techniques such as fourier transform infrared (FTIR), thermogravimetric (TGA), X-ray diffraction (XRD), scanning electron microscopy/ energy dispersive X-ray (SEM/ EDX) and inductively coupled plasma-optical emission (ICP-OES) spectroscopy. (author)

High-performance Platinum-free oxygen reduction reaction and hydrogen oxidation reaction catalyst in polymer electrolyte membrane fuel cell.

Science.gov (United States)

Chandran, Priji; Ghosh, Arpita; Ramaprabhu, Sundara

2018-02-26

The integration of polymer electrolyte membrane fuel cell (PEMFC) stack into vehicles necessitates the replacement of high-priced platinum (Pt)-based electrocatalyst, which contributes to about 45% of the cost of the stack. The implementation of high-performance and durable Pt metal-free catalyst for both oxygen reduction reaction (ORR) and hydrogen oxidation reaction (HOR) could significantly enable large-scale commercialization of fuel cell-powered vehicles. Towards this goal, a simple, scalable, single-step synthesis method was adopted to develop palladium-cobalt alloy supported on nitrogen-doped reduced graphene oxide (Pd 3 Co/NG) nanocomposite. Rotating ring-disk electrode (RRDE) studies for the electrochemical activity towards ORR indicates that ORR proceeds via nearly four-electron mechanism. Besides, the mass activity of Pd 3 Co/NG shows an enhancement of 1.6 times compared to that of Pd/NG. The full fuel cell measurements were carried out using Pd 3 Co/NG at the anode, cathode in conjunction with Pt/C and simultaneously at both anode and cathode. A maximum power density of 68 mW/cm 2 is accomplished from the simultaneous use of Pd 3 Co/NG as both anode and cathode electrocatalyst with individual loading of 0.5 mg/cm 2 at 60 °C without any backpressure. To the best of our knowledge, the present study is the first of its kind of a fully non-Pt based PEM full cell.

Performance of palladium nanoparticle–graphene composite as an efficient electrode material for electrochemical double layer capacitors

International Nuclear Information System (INIS)

Dar, Riyaz A.; Giri, Lily; Karna, Shashi P.; Srivastava, Ashwini K.

2016-01-01

Highlights: • Single step synthesis of palladium nanoparticles decorated-graphene nanocomposite. • Improved electron transfer kinetics and superior capacitive performance. • High specific capacitance of 637 F g −1 at a current density of 1.25 A g −1 . • Retention of 91.4% of its initial capacitance after 10000 cycles of testing. - Abstract: Palladium nanoparticle–graphene nanosheet composite (PdNP–GN) is demonstrated as an efficient electrode material in energy storage applications in supercapacitors. Palladium nanoparticle (PdNP) decorated graphene nanosheet (GN) composite was synthesized via a chemical approach in a single step by the simultaneous reduction of graphene oxide (GO) and palladium chloride from the aqueous phase using ascorbic acid as reducing agent. The materials were characterized by scanning and high resolution transmission electron microscopy, Raman, X-ray diffraction and energy dispersive X-ray spectroscopy which demonstrate that the metal nanoparticles have been uniformly deposited on the surface of graphene nanosheets. The synthesized material has been analyzed by cyclic voltammetry, electrochemical impedance spectrometry and chronopotentiometry using 1 M KCl as the supporting electrolyte for its application in electrochemical double layer supercapacitors. PdNPs-GN composite showed improved electron transfer kinetics and superior capacitive performance with large specific capacitance of 637 F g −1 , excellent cyclic performance and maximum energy and power densities of 56 Wh kg −1 and 1166 W kg −1 , respectively at a current density of 1.25 A g −1 . This highlights the importance of the synergetic effects of electrochemically efficient Pd nanoparticles and graphene for energy storage applications in supercapacitors.

A Palladium-Catalyzed Vinylcyclopropane (3 + 2) Cycloaddition Approach to the Melodinus Alkaloids

KAUST Repository

Goldberg, Alexander F. G.

2011-08-19

A palladium-catalyzed (3+2) cycloaddition of a vinylcyclopropane and a β-nitrostyrene is employed to rapidly assemble the cyclopentane core of the Melodinus alkaloids. The ABCD ring system of the natural product family is prepared in six steps from commercially available materials.

Practical and General Palladium-Catalyzed Synthesis of Ketones from Internal Olefins

KAUST Repository

Morandi, Bill

2013-01-16

Make it simple! A convenient and general palladium-catalyzed oxidation of internal olefins to ketones is reported. The transformation occurs at room temperature and shows wide substrate scope. Applications to the oxidation of seed-oil derivatives and a bioactive natural product (see scheme) are described, as well as intriguing mechanistic features.

Reactivation of a Palladium Catalyst during Glucose Oxidation by Molecular Oxygen

Czech Academy of Sciences Publication Activity Database

Gogová, Zuzana; Hanika, Jiří

2009-01-01

Roč. 63, č. 5 (2009), s. 520-526 ISSN 0366-6352 R&D Projects: GA ČR(CZ) GD203/08/H032 Institutional research plan: CEZ:AV0Z40720504 Keywords : glucose * palladium catalyst * deactivation Subject RIV: CI - Industrial Chemistry, Chemical Engineering Impact factor: 0.791, year: 2009

Practical and General Palladium-Catalyzed Synthesis of Ketones from Internal Olefins

KAUST Repository

Morandi, Bill; Wickens, Zachary K.; Grubbs, Robert H.

2013-01-01

Make it simple! A convenient and general palladium-catalyzed oxidation of internal olefins to ketones is reported. The transformation occurs at room temperature and shows wide substrate scope. Applications to the oxidation of seed-oil derivatives and a bioactive natural product (see scheme) are described, as well as intriguing mechanistic features.

Modelling and sequential simulation of multi-tubular metallic membrane and techno-economics of a hydrogen production process employing thin-layer membrane reactor

KAUST Repository

Shafiee, Alireza; Arab, Mobin; Lai, Zhiping; Liu, Zongwen; Abbas, Ali

2016-01-01

reforming hydrogen production plant. A techno-economic analysis is then conducted using the validated model for a plant producing 300 TPD of hydrogen. The plant utilises a thin (2.5 μm) defect-free and selective layer (Pd75Ag25 alloy) membrane reactor

Palladium on Nitrogen-Doped Mesoporous Carbon: A Bifunctional Catalyst for Formate-Based, Carbon-Neutral Hydrogen Storage.

Science.gov (United States)

Wang, Fanan; Xu, Jinming; Shao, Xianzhao; Su, Xiong; Huang, Yanqiang; Zhang, Tao

2016-02-08

The lack of safe, efficient, and economical hydrogen storage technologies is a hindrance to the realization of the hydrogen economy. Reported herein is a reversible formate-based carbon-neutral hydrogen storage system that is established over a novel catalyst comprising palladium nanoparticles supported on nitrogen-doped mesoporous carbon. The support was fabricated by a hard template method and nitridated under a flow of ammonia. Detailed analyses demonstrate that this bicarbonate/formate redox equilibrium is promoted by the cooperative role of the doped nitrogen functionalities and the well-dispersed, electron-enriched palladium nanoparticles. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Development of metal catalyst impregnation technology for membrane-based oxygen removal system

International Nuclear Information System (INIS)

Kim, Mun Soo; Lee, Doo Ho; Kang, Duk Won

2005-01-01

Dissolved oxygen(DO) is a primary cause of PWSCC and its content in reactor coolant system in NPPs has been strictly controlled by various DO removal methods. There are several removal methods of DO, such as vacuum degasification, thermal deaeration, and reductive removal by oxygen scavengers. Although the operation principles of vacuum degasification and thermal deaeration are simple, these methods require a lot of energy for operation and show lower efficiency. And these methods have a few handicaps such as temperature, pH, toxicity, high cost of installation and so on. For the purpose of developing the best method for DO removal from make-up water storage tank, it is necessary to overcome the disadvantages of hydrazine treatment. From this point of view, membrane-based oxygen removal system (MORS) has many advantages than other methods for example, friendly environmental process, versatility of operation conditions with high temperature and low pressure, small space, low cost, etc. Recently de-gassing membrane is widely used in power plant's feed water system for DO removal. De-gassing membrane has some advantages; it removes other dissolved gases such as CO2, N2, as well as O2, and is more economical than Catalytic resin-based Oxygen Removal System. In this study, to obtain better efficiency of MORS, we modified the polypropylene (PP) hollow fiber membrane by plasma treatment and ion beam irradiation supported platinum(Pt), palladium(Pd) as metal catalyst on the surface of the membrane

Separation of gold, palladium and platinum in chromite by anion exchange chromatography for inductively coupled plasma atomic emission spectrometric analysis

International Nuclear Information System (INIS)

Choi, Kwang Soon; Lee, Chang Heon; Park, Yeong Jae; Joe, Kih Soo; Kim, Won Ho

2001-01-01

A study has been carried out on the separation of gold, iridium, palladium, rhodium, ruthenium and platinum in chromite samples and their quantitative determination using inductively coupled plasma atomic emission spectrometry (ICP-AES). The dissolution condition of the minerals by fusion with sodium peroxide was optimized and chromatographic elution behavior of the rare metals was investigated by anion exchange chromatography. Spectral interference of chromium, a matrix of the minerals, was investigated on determination of gold. Chromium interfered on determination of gold at the concentration of 500 mg/L and higher. Gold plus trace amounts of iridium, palladium, rhodium and ruthenium, which must be preconcentrated before ICP-AES was separated by anion exchange chromatography after reducing Cr(VI) to Cr(III) by H 2 O 2 . AuCl - 4 retained on the resin column was selectively eluted with acetone- HNO 3 -H 2 O as an eluent. In addition, iridium, palladium, rhodium and ruthenium remaining on the resin column were eluted as a group with concentrated HCl. However, platinum was eluted with concentrated HNO 3 . The recovery yield of gold with acetone-HNO 3 -H 2 O was 100.7 ± 2.0 % , and the yields of palladium and platinum with concentrated HCl and HNO 3 were 96.1 ± 1.8% and 96.6 ± 1.3%, respectively. The contents of gold and platinum in a Mongolian chromite sample were 32.6 ± 2.2 μg/g and 1.6 ± 0.14 μg/g, respectively. Palladium was not detected

Palladium polypyridyl complexes: synthesis, characterization, DNA interaction and biological activity on Leishmania (L.) mexicana

International Nuclear Information System (INIS)

Navarro, Maribel; Betancourt, Adelmo; Hernandez, Clara; Marchan, Edgar

2008-01-01

This paper describes the search for new potential chemotherapeutic agents based on transition metal complexes with planar ligands. In this study, palladium polypyridyl complexes were synthesized and characterized by elemental analysis, NMR, UV-VIS and IR spectroscopies. The interaction of the complexes with DNA was also investigated by spectroscopic methods. All metal-to-ligand charge transfer (MLCT) bands of the palladium polypyridyl complexes exhibited hypochromism and red shift in the presence of DNA. The binding constant and viscosity data suggested that the complexes [PdCl 2 (phen)] and [PdCl 2 (phendiamine)] interact with DNA by electrostatic forces. Additionally, these complexes induced an important leishmanistatic effect on L. (L.) mexicana promastigotes at the final concentration of 10 μmol L -1 in 48 h. (author)

Synthesis of Nitriles via Palladium-Catalyzed Water Shuffling from Amides to Acetonitrile

OpenAIRE

Zhang, Wandi; Haskins, Christopher W.; Yang, Yang; Dai, Mingji

2014-01-01

Palladium-catalyzed synthesis of nitriles from amides has been described. Two similar, but complementary reaction conditions have been identified to convert various amides including α,β,γ,δ-unsaturated amides, cinnamides, aromatic amides and alkyl amides to the corresponding nitriles in good to excellent yield.

Synthesis of nitriles via palladium-catalyzed water shuffling from amides to acetonitrile.

Science.gov (United States)

Zhang, Wandi; Haskins, Christopher W; Yang, Yang; Dai, Mingji

2014-12-07

Palladium-catalyzed synthesis of nitriles from amides has been described. Two similar, but complementary reaction conditions have been identified to convert various amides including α,β,γ,δ-unsaturated amides, cinnamides, aromatic amides and alkyl amides to the corresponding nitriles in good to excellent yield.

Optical hydrogen sensors based on metal-hydrides

Science.gov (United States)

Slaman, M.; Westerwaal, R.; Schreuders, H.; Dam, B.

2012-06-01

For many hydrogen related applications it is preferred to use optical hydrogen sensors above electrical systems. Optical sensors reduce the risk of ignition by spark formation and are less sensitive to electrical interference. Currently palladium and palladium alloys are used for most hydrogen sensors since they are well known for their hydrogen dissociation and absorption properties at relatively low temperatures. The disadvantages of palladium in sensors are the low optical response upon hydrogen loading, the cross sensitivity for oxygen and carbon, the limited detection range and the formation of micro-cracks after some hydrogen absorption/desorption cycles. In contrast to Pd, we find that the use of magnesium or rear earth bases metal-hydrides in optical hydrogen sensors allow tuning of the detection levels over a broad pressure range, while maintaining a high optical response. We demonstrate a stable detection layer for detecting hydrogen below 10% of the lower explosion limit in an oxygen rich environment. This detection layer is deposited at the bare end of a glass fiber as a micro-mirror and is covered with a thin layer of palladium. The palladium layer promotes the hydrogen uptake at room temperature and acts as a hydrogen selective membrane. To protect the sensor for a long time in air a final layer of a hydrophobic fluorine based coating is applied. Such a sensor can be used for example as safety detector in automotive applications. We find that this type of fiber optic hydrogen sensor is also suitable for hydrogen detection in liquids. As example we demonstrate a sensor for detecting a broad range of concentrations in transformer oil. Such a sensor can signal a warning when sparks inside a high voltage power transformer decompose the transformer oil over a long period.

Palladium(II)-catalyzed desulfitative synthesis of aryl ketones from sodium arylsulfinates and nitriles: scope, limitations, and mechanistic studies.

Science.gov (United States)

Skillinghaug, Bobo; Sköld, Christian; Rydfjord, Jonas; Svensson, Fredrik; Behrends, Malte; Sävmarker, Jonas; Sjöberg, Per J R; Larhed, Mats

2014-12-19

A fast and efficient protocol for the palladium(II)-catalyzed production of aryl ketones from sodium arylsulfinates and various organic nitriles under controlled microwave irradiation has been developed. The wide scope of the reaction has been demonstrated by combining 14 sodium arylsulfinates and 21 nitriles to give 55 examples of aryl ketones. One additional example illustrated that, through the choice of the nitrile reactant, benzofurans are also accessible. The reaction mechanism was investigated by electrospray ionization mass spectrometry and DFT calculations. The desulfitative synthesis of aryl ketones from nitriles was also compared to the corresponding transformation starting from benzoic acids. Comparison of the energy profiles indicates that the free energy requirement for decarboxylation of 2,6-dimethoxybenzoic acid and especially benzoic acid is higher than the corresponding desulfitative process for generating the key aryl palladium intermediate. The palladium(II) intermediates detected by ESI-MS and the DFT calculations provide a detailed understanding of the catalytic cycle.

A new metal electrocatalysts supported matrix: Palladium nanoparticles supported silicon carbide nanoparticles and its application for alcohol electrooxidation

International Nuclear Information System (INIS)

Dai Hong; Chen Yanling; Lin Yanyu; Xu Guifang; Yang Caiping; Tong Yuejin; Guo Longhua; Chen Guonan

2012-01-01

In this paper, we propose a facile approach for palladium nanoparticles load using silicon carbide nanoparticles as the new supported matrix and a familiar NaBH 4 as reducer. Detailed X-ray photoelectron spectrum (XPS) and transmission electron microscopy (TEM) analysis of the resultant products indicated that palladium nanoparticles are successfully immobilized onto the surface of the silicon carbide nanoparticles with uniform size distribution between 5 and 7 nm. The relative electrochemical characterization clearly demonstrated excellent electrocatalytic activity of this material toward alcohol in alkaline electrolytes. Investigation on the characteristics of the electrocatalytic activity of this material further indicated that the palladium nanoparticles supporting on SiC are very promising for direct alcohol fuel cells (DMFCs), biosensor and electronic devices. Moreover, it was proved that silicon carbide nanoparticles with outstanding properties as support for catalysis are of strong practical interest. And the silicon carbide could perform attractive role in adsorbents, electrodes, biomedical applications, etc.

Dinuclear Tetrapyrazolyl Palladium Complexes Exhibiting Facile Tandem Transfer Hydrogenation/Suzuki Coupling Reaction of Fluoroarylketone

KAUST Repository

Dehury, Niranjan; Maity, Niladri; Tripathy, Suman Kumar; Basset, Jean-Marie; Patra, Srikanta

2016-01-01

Herein, we report an unprecedented example of dinuclear pyrazolyl-based Pd complexes exhibiting facile tandem catalysis for fluoroarylketone: Tetrapyrazolyl di-palladium complexes with varying Pd-Pd distances efficiently catalyze the tandem reaction

Palladium-catalyzed aerobic oxidative cross-coupling of arylhydrazines with terminal alkynes.

Science.gov (United States)

Zhao, Yingwei; Song, Qiuling

2015-09-04

The palladium-catalyzed Sonogashira-type aerobic oxidative coupling of arylhydrazines with terminal alkynes via C-N bond cleavage has been developed; internal alkynes were afforded with a broad substrate scope. This reaction proceeds under copper- and base-free conditions with molecular oxygen as the sole oxidant and nitrogen and water as the only by-products.

Palladium nanoparticles anchored on graphene nanosheets: Methanol, ethanol oxidation reactions and their kinetic studies

Energy Technology Data Exchange (ETDEWEB)

Nagaraju, D.H., E-mail: dhnagu@gmail.com [Department of Mechanical Engineering, 117 576 (Singapore); Materials Science and Engineering, King Abdullah University of Science and Technology (KAUST), Thuwal, 23955-6900 (Saudi Arabia); Devaraj, S. [Department of Mechanical Engineering, 117 576 (Singapore); School of Chemical and Biotechnology, SASTRA University, Thanjavur, 613 401 (India); Balaya, P., E-mail: mpepb@nus.edu.sg [Department of Mechanical Engineering, 117 576 (Singapore); Engineering Science Program, National University of Singapore, 117 576 (Singapore)

2014-12-15

Highlights: • Palladium nanoparticles decorated graphene is synthesized in a single step. • Electro-catalytic activity of Gra/Pd toward alcohol oxidation is evaluated. • 1:1 Gra/Pd exhibits good electro-catalytic activity and efficient electron transfer. - Abstract: Palladium nanoparticles decorated graphene (Gra/Pd nanocomposite) was synthesized by simultaneous chemical reduction of graphene oxide and palladium salt in a single step. The negatively charged graphene oxide (GO) facilitates uniform distribution of Pd{sup 2+} ions onto its surface. The subsequent reduction by hydrazine hydrate provides well dispersed Pd nanoparticles decorated graphene. Different amount of Pd nanoparticles on graphene was synthesized by changing the volume to weight ratio of GO to PdCl{sub 2}. X-ray diffraction studies showed FCC lattice of Pd with predominant (1 1 1) plane. SEM and TEM studies revealed that thin graphene nanosheets are decorated by Pd nanoparticles. Raman spectroscopic studies revealed the presence of graphene nanosheets. The electro-catalytic activity of Gra/Pd nanocomposites toward methanol and ethanol oxidation in alkaline medium was evaluated by cyclic voltammetric studies. 1:1 Gra/Pd nanocomposite exhibited good electro-catalytic activity and efficient electron transfer. The kinetics of electron transfer was studied using chronoamperometry. Improved electro-catalytic activity of 1:1 Gra/Pd nanocomposite toward alcohol oxidation makes it as a potential anode for the alcohol fuel cells.

High stability of palladium/kieselguhr composites during absorption/desorption cycling for hydrogen isotope separation

Energy Technology Data Exchange (ETDEWEB)

Lei, Yang, E-mail: lei.y@outlook.com; Liu, Xiaopeng; Li, Shuo; Jiang, Lijun; Zhang, Chao; Li, Shuai; He, Di; Wang, Shumao

2016-12-15

Highlights: • Pd/K composites with as high as 57 wt.% of Pd have been successfully prepared. • Palladium particles can be effectively packed into the pores of kieselguhr substrates. • Variation of heat-treatment temperatures hardly affect hydrogen absorption capacity and hydrogen saturation time of the Pd/K. • Anti-pulverization property of Pd/K can be improved by packing palladium into the kieselguhr internal pores and heating at 1300 °C. - Abstract: Palladium/kieselguhr (Pd/K) composites with 57 wt.% of Pd were prepared by an improved dipping and thermal decomposition method and heated at elevated temperature to reduce breakdown during hydrogenation-dehydrogenation cycles. The hydrogen absorption kinetic properties of the samples heated at different temperatures were tested under the condition of 20 °C with 100 kPa hydrogen pressure. The 1300 °C heated Pd/K composites were repeated up to 4010 absorption and desorption cycles at temperature ranges between −40 °C and 200 °C. The results show that the phase structure, hydrogen absorption capacity and hydrogen saturation time of the Pd/K were not affected by the change of heat-treated temperatures. And after heat treatment at 1300 °C, the Pd/K particles were strengthened and fraction of larger than 80 mesh were as high as 93.4%.

Palladium nanoparticles anchored on graphene nanosheets: Methanol, ethanol oxidation reactions and their kinetic studies

International Nuclear Information System (INIS)

Nagaraju, D.H.; Devaraj, S.; Balaya, P.

2014-01-01

Highlights: • Palladium nanoparticles decorated graphene is synthesized in a single step. • Electro-catalytic activity of Gra/Pd toward alcohol oxidation is evaluated. • 1:1 Gra/Pd exhibits good electro-catalytic activity and efficient electron transfer. - Abstract: Palladium nanoparticles decorated graphene (Gra/Pd nanocomposite) was synthesized by simultaneous chemical reduction of graphene oxide and palladium salt in a single step. The negatively charged graphene oxide (GO) facilitates uniform distribution of Pd 2+ ions onto its surface. The subsequent reduction by hydrazine hydrate provides well dispersed Pd nanoparticles decorated graphene. Different amount of Pd nanoparticles on graphene was synthesized by changing the volume to weight ratio of GO to PdCl 2 . X-ray diffraction studies showed FCC lattice of Pd with predominant (1 1 1) plane. SEM and TEM studies revealed that thin graphene nanosheets are decorated by Pd nanoparticles. Raman spectroscopic studies revealed the presence of graphene nanosheets. The electro-catalytic activity of Gra/Pd nanocomposites toward methanol and ethanol oxidation in alkaline medium was evaluated by cyclic voltammetric studies. 1:1 Gra/Pd nanocomposite exhibited good electro-catalytic activity and efficient electron transfer. The kinetics of electron transfer was studied using chronoamperometry. Improved electro-catalytic activity of 1:1 Gra/Pd nanocomposite toward alcohol oxidation makes it as a potential anode for the alcohol fuel cells

Chromatographic enrichment of isotopes in hydrogen and water samples on palladium

International Nuclear Information System (INIS)

Andreev, B.M.; Polevoi, A.S.; Perevezentsev, A.N.

1987-01-01

Data on the isotopic enrichment of hydrogen and water samples by chromatography on palladium have been analyzed. Experimental data on the effect of temperature, hydrogen flow, volume of the enriched fraction, and length of the chromatographic column on the degree of separation attainable in the column have been obtained. It has been shown that the maximum separation achievable (regardless of the type of the isotope mixture) at 273 K falls with increase of hydrogen flow and volume of the enriched gas fraction recoverable from the column. A separation degree of ∼ 1040 has been achieved for a mixture of protium and deuterium in a 10-mm wide and 0.6-m long chromatographic column packed with palladium black with a grain size of 0.2-0.5 mm at 273 K and a specific hydrogen flow of 1.22 mole/m 2 x sec. For a protium-tritium mixture a separation degree of ∼ 90 has been reached in a similar column at 273 K and a specific hydrogen flow of 0.4 mole/m 2 x sec

A Colorimetric Chemodosimeter for Pd(II): A Method for Detecting Residual Palladium in Cross-Coupling Reactions

Science.gov (United States)

Houk, Ronald J. T.; Wallace, Karl J.; Hewage, Himali S.; Anslyn, Eric V.

2008-01-01

A colorimetric chemodosimeter (SQ1) for the detection of trace palladium salts in cross-coupling reactions mediated by palladium is described. Decolorization of SQ1 is affected by nucleophilic attack of ethanethiol in basic DMSO solutions. Thiol addition is determined to have an equilibrium constant (Keq) of 2.9 × 106 M-1, with a large entropic and modest enthalpic driving force. This unusual result is attributed to solvent effects arising from a strong coordinative interaction between DMSO and the parent squaraine. Palladium detection is achieved through thiol scavenging from the SQ1-ethanethiol complex leading to a color “turn-on” of the parent squaraine. It was found that untreated samples obtained directly from Suzuki couplings showed no response to the assay. However, treatment of the samples with aqueous nitric acid generates a uniform Pd(NO3)2 species, which gives an appropriate response. “Naked-eye” detection of Pd(NO3)2 was estimated to be as low as 0.5 ppm in solution, and instrument-based detection was tested as low as 100 ppb. The average error over the working range of the assay was determined to be 7%. PMID:19122841

System design study of a membrane reforming hydrogen production plant using a small sized sodium cooled reactor

International Nuclear Information System (INIS)

Chikazawa, Y.; Konomura, M.; Hori, T.; Sato, H.; Uchida, S.

2004-01-01

In this study, a membrane reforming hydrogen production plant using a small sized sodium cooled reactor was designed as one of promising concepts. In the membrane reformer, methane and steam are reformed into carbon dioxide and hydrogen with sodium heat at a temperature 500 deg-C. In the equilibrium condition, steam reforming proceeds with catalyst at a temperature more than 800 deg-C. Using membrane reformers, the steam reforming temperature can be decreased from 800 to 500 deg-C because the hydrogen separation membrane removes hydrogen selectively from catalyst area and the partial pressure of hydrogen is kept much lower than equilibrium condition. In this study, a hydrogen and electric co-production plant has been designed. The reactor thermal output is 375 MW and 25% of the thermal output is used for hydrogen production (70000 Nm 3 /h). The hydrogen production cost is estimated to 21 yen/Nm 3 but it is still higher than the economical goal (17 yen/Nm 3 ). The major reason of the high cost comes from the large size of hydrogen separation reformers because of the limit of hydrogen separation efficiency of palladium membrane. A new highly efficient hydrogen separation membrane is needed to reduce the cost of hydrogen production using membrane reformers. There is possibility of multi-tube failure in the membrane reformers. In future study, a design of measures against tube failure and elemental experiments of reaction between sodium and reforming gas will be needed. (authors)

Reversible, high molecular weight palladium and platinum coordination polymers based on phosphorus ligands

NARCIS (Netherlands)

Paulusse, J.M.J.; Huijbers, J.P.J.; Sijbesma, R.P.

2005-01-01

A general strategy for the preparation and characterization of high molecular weight coordination polymers based on bifunctional phosphorus ligands and palladium or platinum dichloride is described. Metal-to-ligand stoichiometry is of key importance for the formation of linear coordination polymers

Reversible, High Molecular Weight Palladium and Platinum Coordination Polymers Based on Phosphorus Ligands

NARCIS (Netherlands)

Paulusse, Jos Marie Johannes; Huijbers, Jeroen P.J.; Sijbesma, Rint P.

2005-01-01

A general strategy for the preparation and characterization of high molecular weight coordination polymers based on bifunctional phosphorus ligands and palladium or platinum dichloride is described. Metal-to-ligand stoichiometry is of key importance for the formation of linear coordination polymers

Influence of Chromium-Cobalt-Molybdenum Alloy (ASTM F75 on Bone Ingrowth in an Experimental Animal Model

Directory of Open Access Journals (Sweden)

Jésica Zuchuat

2017-12-01

Full Text Available Cr-Co-Mo (ASTM F75 alloy has been used in the medical environment, but its use as a rigid barrier membrane for supporting bone augmentation therapies has not been extensively investigated. In the present study, Cr-Co-Mo membranes of different heights were placed in New Zealand white, male rabbit tibiae to assess the quality and volume of new bone formation, without the use of additional factors. Animals were euthanized at 20, 30, 40, and 60 days. Bone formation was observed in all of the cases, although the tibiae implanted with the standard membranes reached an augmentation of bone volume that agreed with the density values over the timecourse. In all cases, plasmatic exudate was found under the membrane and in contact with the new bone. Histological analysis indicated the presence of a large number of chondroblasts adjacent to the inner membrane surface in the first stages, and osteoblasts and osteocytes were observed under them. The bone formation was appositional. The Cr-Co-Mo alloy provides a scaffold with an adequate microenvironment for vertical bone volume augmentation, and the physical dimensions and disposition of the membrane itself influence the new bone formation.

Influence of Chromium-Cobalt-Molybdenum Alloy (ASTM F75) on Bone Ingrowth in an Experimental Animal Model.

Science.gov (United States)

Zuchuat, Jésica; Berli, Marcelo; Maldonado, Ysaí; Decco, Oscar

2017-12-26

Cr-Co-Mo (ASTM F75) alloy has been used in the medical environment, but its use as a rigid barrier membrane for supporting bone augmentation therapies has not been extensively investigated. In the present study, Cr-Co-Mo membranes of different heights were placed in New Zealand white, male rabbit tibiae to assess the quality and volume of new bone formation, without the use of additional factors. Animals were euthanized at 20, 30, 40, and 60 days. Bone formation was observed in all of the cases, although the tibiae implanted with the standard membranes reached an augmentation of bone volume that agreed with the density values over the timecourse. In all cases, plasmatic exudate was found under the membrane and in contact with the new bone. Histological analysis indicated the presence of a large number of chondroblasts adjacent to the inner membrane surface in the first stages, and osteoblasts and osteocytes were observed under them. The bone formation was appositional. The Cr-Co-Mo alloy provides a scaffold with an adequate microenvironment for vertical bone volume augmentation, and the physical dimensions and disposition of the membrane itself influence the new bone formation.

Efficiency of Al2O3 supported palladium sorbents in the process of hydrogen isotope exchange

International Nuclear Information System (INIS)

Andreev, B.M.; Perevezentsev, A.N.; Yasenkov, V.I.

1981-01-01

It is found that in the hydrogen-palladium system while applying the metal to aluminium oxide a considerable increase of the heterogeneous hydrogen isotopic exchange rate is observed due to the increase of its specific surface at 167-298 K temperatures and 350-500 Torr hydrogen pressures. It is shown that in the process of thermal treatment of the supported palladium sorbent resulting in reconstruction of the carrier porous structure, as well as in increasing the metal crystal size, the change of the stage, limiting the isotopic exchange process, occurs. The values of the rate and energy of activation of the hydrogen isotopic exchange are presented [ru

Interaction of ethylene with palladium clusters supported on oxidized tungsten foil

Czech Academy of Sciences Publication Activity Database

Jirka, Ivan; Plšek, Jan; Vondráček, Martin; Šutara, F.; Matolin, V.; Cháb, Vladimír; Prince, K. C.

2007-01-01

Roč. 601, č. 14 (2007), s. 3114-3124 ISSN 0039-6028 R&D Projects: GA ČR(CZ) GA202/05/0244 Institutional research plan: CEZ:AV0Z40400503; CEZ:AV0Z10100521 Keywords : synchrotron radiation photoelectron spectroscopy * thermal desorption spectroscopy * chemisorption * palladium Subject RIV: CF - Physical ; Theoretical Chemistry Impact factor: 1.855, year: 2007

Assembling strategy to synthesize palladium modified kaolin nanocomposites with different morphologies

OpenAIRE

Li, Xiaoyu; Ouyang, Jing; Zhou, Yonghua; Yang, Huaming

2015-01-01

Nanocomposites of aluminosilicate minerals, kaolins (kaolinite and halloysite) with natural different morphologies assembling with palladium (Pd) nanoparticles have been successfully synthesized through strong electrostatic adsorption and chemical bonding after surface modification with 3-aminopropyl triethoxysilane (APTES). Meanwhile, the influence of different morphologies supports on catalytic hydrogenation properties was explored. The surface concentration of amino groups on the kaolins w...

Electrochemical behavior of ruthenium (III), rhodium (III) and palladium (II) in 1-butyl-3-methylimidazolium chloride ionic liquid

Energy Technology Data Exchange (ETDEWEB)

Jayakumar, M.; Venkatesan, K.A. [Fuel Chemistry Division, Indira Gandhi Centre for Atomic Research, Kalpakkam 603102 (India); Srinivasan, T.G. [Fuel Chemistry Division, Indira Gandhi Centre for Atomic Research, Kalpakkam 603102 (India)], E-mail: tgs@igcar.gov.in; Vasudeva Rao, P.R. [Fuel Chemistry Division, Indira Gandhi Centre for Atomic Research, Kalpakkam 603102 (India)

2009-11-01

Electrochemical behavior of ruthenium (III), rhodium (III) and palladium (II) in 1-butyl-3-methylimidazolium chloride (bmimCl) and their ternary and binary solutions in bmimCl was studied at various working electrodes at 373 K by cyclic voltammetry and chronoamperometry. Ruthenium (III) chloride forms a stable solution with bmimCl and the cyclic voltammogram of ruthenium (III) in bmimCl recorded at glassy carbon electrode consisted of several redox waves due to the complex nature of ruthenium to exist in several oxidation states. Electrolysis of ruthenium (III) chloride in bmimCl at the cathodic limit of bmimCl (-1.8 V (vs. Pd)) did not result in ruthenium metal deposition. However, it was deposited from bmimPF{sub 6} and bmimNTf{sub 2} room temperature ionic liquids at -0.8 V (vs. Pd). The electrochemical behavior of ruthenium (III) in bmimCl in the presence of palladium (II) and rhodium (III) was studied by cyclic voltammetry. The presence of palladium (II) in bmimCl favors underpotential deposition of ruthenium metal. The nuclear loop at -0.5 V (vs. Pd) was observed in all solutions when palladium (II) co-existed with other two metal ions. Nucleation and growth of the metal on glassy carbon working electrode was investigated by chronoamperometry. The growth and decay of chronocurrents has been found to follow the instantaneous nucleation model with three-dimensional growth of nuclei.

Palladium polypyridyl complexes: synthesis, characterization, DNA interaction and biological activity on Leishmania (L.) mexicana

Energy Technology Data Exchange (ETDEWEB)

Navarro, Maribel [Instituto Venezolano de Investigaciones Cientificas, Caracas (Venezuela). Centro de Quimica; Betancourt, Adelmo [Universidad de Carabobo, Valencia (Venezuela). Facultad Experimental de Ciencia y Tecnologia. Dept. de Quimica; Hernandez, Clara [Universidad de Carabobo Sede Aragua, Maracay (Venezuela). Facultad de Ciencias de la Salud. Dept. de Ciencias Basicas; Marchan, Edgar [Universidad de Oriente, Cumana (Venezuela). Inst. de Investigaciones en Biomedicina y Ciencias Aplicadas. Nucleo de Sucre

2008-07-01

This paper describes the search for new potential chemotherapeutic agents based on transition metal complexes with planar ligands. In this study, palladium polypyridyl complexes were synthesized and characterized by elemental analysis, NMR, UV-VIS and IR spectroscopies. The interaction of the complexes with DNA was also investigated by spectroscopic methods. All metal-to-ligand charge transfer (MLCT) bands of the palladium polypyridyl complexes exhibited hypochromism and red shift in the presence of DNA. The binding constant and viscosity data suggested that the complexes [PdCl{sub 2}(phen)] and [PdCl{sub 2}(phendiamine)] interact with DNA by electrostatic forces. Additionally, these complexes induced an important leishmanistatic effect on L. (L.) mexicana promastigotes at the final concentration of 10 {mu}mol L{sup -1} in 48 h. (author)

Palladium nanoparticles exposure: Evaluation of permeation through damaged and intact human skin.

Science.gov (United States)

Larese Filon, Francesca; Crosera, Matteo; Mauro, Marcella; Baracchini, Elena; Bovenzi, Massimo; Montini, Tiziano; Fornasiero, Paolo; Adami, Gianpiero

2016-07-01

The intensified use of palladium nanoparticles (PdNPs) in many chemical reactions, jewellery, electronic devices, in car catalytic converters and in biomedical applications lead to a significant increase in palladium exposure. Pd can cause allergic contact dermatitis when in contact with the skin. However, there is still a lack of toxicological data related to nano-structured palladium and information on human cutaneous absorption. In fact, PdNPs, can be absorbed through the skin in higher amounts than bulk Pd because NPs can release more ions. In our study, we evaluated the absorption of PdNPs, with a size of 10.7 ± 2.8 nm, using intact and damaged human skin in Franz cells. 0.60 mg cm(-2) of PdNPs were applied on skin surface for 24 h. Pd concentrations in the receiving solutions at the end of experiments were 0.098 ± 0.067 μg cm(-2) and 1.06 ± 0.44 μg cm(-2) in intact skin and damaged skin, respectively. Pd flux permeation after 24 h was 0.005 ± 0.003 μg cm(-2) h(-1) and 0.057 ± 0.030 μg cm(-2) h(-1) and lag time 4.8 ± 1.7 and 4.2 ± 3.6 h, for intact and damaged skin respectively. This study indicates that Pd can penetrate human skin. Copyright © 2016 Elsevier Ltd. All rights reserved.

Oxidative addition of aryl chlorides to monoligated palladium(0): A DFT-SCRF study

DEFF Research Database (Denmark)

Ahlquist, Mårten Sten Gösta; Norrby, Per-Ola

2007-01-01

Oxidative addition of aryl chlorides to palladium has been investigated by hybrid density functional theory methods (B3LYP), including a continuum model describing the solvent implicitly. A series of para-substituted aryl chlorides were studied to see the influence of electronic effects...

Palladium-Catalysed Direct Cross-Coupling of Organolithium Reagents with Aryl and Vinyl Triflates

NARCIS (Netherlands)

Vila, Carlos; Hornillos, Valentin; Giannerini, Massimo; Fananas-Mastral, Martin; Feringa, Bernard L.

2014-01-01

Carbon-Carbon Bond Formation Carbon-carbon bond formation by the cross-coupling of highly reactive organolithium reagents is a major challenge. Recently, it was demonstrated that palladium catalysts are able to couple organic halides with various organolithium species under mild conditions in a

Density functional study on the mechanism for the highly active palladium monolayer supported on titanium carbide for the oxygen reduction reaction

International Nuclear Information System (INIS)

Mao, Jianjun; Zhang, Yanxing; Chu, Xingli; Li, Shasha; Yang, Zongxian

2016-01-01

The adsorption, diffusion, and dissociation of O 2 on the palladium monolayer supported on TiC(001) surface, MLPd/TiC(001), are investigated using ab initio density functional theory calculations. Strong adhesion of palladium monolayer to the TiC(001) support, accompanied by a modification of electronic structure of the supported palladium, is evidenced. Compared with Pt(111) surface, the MLPd/TiC(001) can enhance the adsorption of O 2 , leading to comparable dissociation barrier and a smaller diffusion barrier of O 2 . Whilst the adsorption strength of atomic O (the dissociation product of O 2 ) on MLPd/TiC(001) is similar to that on the Pt(111) surface, possessing high mobility, our theoretical results indicate that MLPd/TiC(001) may serve as a good catalyst for the oxygen reduction reaction.

Development of chiral terminal-alkene-phosphine hybrid ligands for palladium-catalyzed asymmetric allylic substitutions.

Science.gov (United States)

Liu, Zhaoqun; Du, Haifeng

2010-07-02

A variety of novel chiral terminal-alkene-phosphine hybrid ligands were successfully developed from diethyl L-tartrate for palladium-catalyzed asymmetric allylic alkylations, etherifications, and amination to give the desired products in excellent yields and ee's.

Accelerating Palladium Nanowire H2 Sensors Using Engineered Nanofiltration.

Science.gov (United States)

Koo, Won-Tae; Qiao, Shaopeng; Ogata, Alana F; Jha, Gaurav; Jang, Ji-Soo; Chen, Vivian T; Kim, Il-Doo; Penner, Reginald M

2017-09-26

The oxygen, O 2 , in air interferes with the detection of H 2 by palladium (Pd)-based H 2 sensors, including Pd nanowires (NWs), depressing the sensitivity and retarding the response/recovery speed in air-relative to N 2 or Ar. Here, we describe the preparation of H 2 sensors in which a nanofiltration layer consisting of a Zn metal-organic framework (MOF) is assembled onto Pd NWs. Polyhedron particles of Zn-based zeolite imidazole framework (ZIF-8) were synthesized on lithographically patterned Pd NWs, leading to the creation of ZIF-8/Pd NW bilayered H 2 sensors. The ZIF-8 filter has many micropores (0.34 nm for gas diffusion) which allows for the predominant penetration of hydrogen molecules with a kinetic diameter of 0.289 nm, whereas relatively larger gas molecules including oxygen (0.345 nm) and nitrogen (0.364 nm) in air are effectively screened, resulting in superior hydrogen sensing properties. Very importantly, the Pd NWs filtered by ZIF-8 membrane (Pd NWs@ZIF-8) reduced the H 2 response amplitude slightly (ΔR/R 0 = 3.5% to 1% of H 2 versus 5.9% for Pd NWs) and showed 20-fold faster recovery (7 s to 1% of H 2 ) and response (10 s to 1% of H 2 ) speed compared to that of pristine Pd NWs (164 s for response and 229 s for recovery to 1% of H 2 ). These outstanding results, which are mainly attributed to the molecular sieving and acceleration effect of ZIF-8 covered on Pd NWs, rank highest in H 2 sensing speed among room-temperature Pd-based H 2 sensors.

Palladium catalyzed selective distal C-H olefination of biaryl systems.

Science.gov (United States)

Maity, Soham; Hoque, Ehtasimul; Dhawa, Uttam; Maiti, Debabrata

2016-11-29

Palladium catalyzed selective distal C-H activation with nitrile based templates has been of significant research interest in recent times. In this report, we disclose the distal C-H olefination of biphenyl systems with high regio- and stereo-selectivity and useful synthetic yields. The utility of this method has been demonstrated through its wide olefin scope, its operation at the gram scale and the easy removal/recovery of the directing group.

Application of Colloidal Palladium Nanoparticles for Labeling in Electron Microscopy

Czech Academy of Sciences Publication Activity Database

Vancová, Marie; Šlouf, Miroslav; Langhans, Jan; Pavlová, Eva; Nebesářová, Jana

2011-01-01

Roč. 17, č. 5 (2011), s. 810-816 ISSN 1431-9276 R&D Projects: GA AV ČR KAN200520704; GA AV ČR KJB600960906; GA ČR GAP205/10/0348 Institutional research plan: CEZ:AV0Z60220518; CEZ:AV0Z40500505 Keywords : electron microscopy * colloidal palladium * nanoparticles * labeling * salivary glands * Ixodes ricinus Subject RIV: CF - Physical ; Theoretical Chemistry Impact factor: 3.007, year: 2011

p-chloro- and p-bromo-benzoylacetoneoxime as the spectrophotometric reagents for palladium and ruthenium(III)

International Nuclear Information System (INIS)

Yeole, V.V.; Langade, A.D.; Shinde, V.M.

1980-01-01

A procedure is described for the extractive spectrophotometric determination of palladium or ruthenium(III) using p-chloro or p-bromobenzoylacetoneoxime as the reagent. The yellow palladium complexes which are extracted into chloroform from an aqueous solution of pH 3.5, absorb as 400 nm and conform to Beer's law in the range of 10 to 100 μg of Pd/10 ml of organic phase. The orange-red ruthenium complexes which are extracted into ethylacetate from an aqueous solution of pH 5.0, absorbs at 475 nm and conforms to Beer's law in the range of 20 to 200 μg of Ru/10 ml of organic phase. The molar absorptivities, Sandell's sensitivities and instability constants are reported. (author)

A simple method to deposit palladium doped SnO2 thin films using plasma enhanced chemical vapor deposition technique

International Nuclear Information System (INIS)

Kim, Young Soon; Wahab, Rizwan; Shin, Hyung-Shik; Ansari, S. G.; Ansari, Z. A.

2010-01-01

This work presents a simple method to deposit palladium doped tin oxide (SnO 2 ) thin films using modified plasma enhanced chemical vapor deposition as a function of deposition temperature at a radio frequency plasma power of 150 W. Stannic chloride (SnCl 4 ) was used as precursor and oxygen (O 2 , 100 SCCM) (SCCM denotes cubic centimeter per minute at STP) as reactant gas. Palladium hexafluroacetyleacetonate (Pd(C 5 HF 6 O 2 ) 2 ) was used as a precursor for palladium. Fine granular morphology was observed with tetragonal rutile structure. A peak related to Pd 2 Sn is observed, whose intensity increases slightly with deposition temperature. Electrical resistivity value decreased from 8.6 to 0.9 mΩ cm as a function of deposition temperature from 400 to 600 deg. C. Photoelectron peaks related to Sn 3d, Sn 3p3, Sn 4d, O 1s, and C 1s were detected with varying intensities as a function of deposition temperature.

Alternative products to carbazoles in the oxidation of diphenylamines with palladium (II) acetate

OpenAIRE

Raposo, M. Manuela M.; Campos, Ana M. F. Oliveira; Shannon, Patrick V. R.

1997-01-01

Although simple diphenylamines are conveniently oxidised with Palladium (II) acetate to give carbazoles, for more complex examples, carbazoles are minor products amongst many. CRUP (Portugal). British Council - Treaty of Windsor Programme. Junta Nacional de Investigação Científica e Tecnológica.

Memory effects in palladium-catalyzed allylic Alkylations of 2-cyclohexen-1-yl acetate

DEFF Research Database (Denmark)

Svensen, Nina; Fristrup, Peter; Tanner, David Ackland

2007-01-01

The objective of this work was to characterize the enantiospecificity of the allylic alkylation of enantioenriched 2-cyclohexen-1-yl acetate with the enolate ion of dimethyl malonate catalyzed by unsymmetrical palladium catalysts. The precatalysts employed were (eta(3)-allyl)PdLCl, where L...

Effect of Processing Parameters on Pore Structure and Thickness of Anodic Aluminum Oxide (AAO) Tubular Membranes

OpenAIRE

Belwalkar, A.; Grasing, E.; Van Geertruyden, W.; Huang, Z.; Misiolek, W.Z.

2008-01-01

Nanoporous anodic aluminum oxide (AAO) tubular membranes were fabricated from aluminum alloy tubes in sulfuric and oxalic acid electrolytes using a two-step anodization process. The membranes were investigated for characteristics such as pore size, interpore distance and thickness by varying applied voltage and electrolyte concentration. Morphology of the membranes was examined using light optical and scanning electron microscopy and characterized using ImageJ software. Results showed that me...

Fabrication of Nitrogen-Doped Mesoporous-Carbon-Coated Palladium Nanoparticles: An Intriguing Electrocatalyst for Methanol and Formic Acid Oxidation.

Science.gov (United States)

Ray, Chaiti; Dutta, Soumen; Sahoo, Ramkrishna; Roy, Anindita; Negishi, Yuichi; Pal, Tarasankar

2016-05-20

Inspired by the attractive catalytic properties of palladium and the inert nature of carbon supports in catalysis, a concise and simple methodology for in situ nitrogen-doped mesoporous-carbon-supported palladium nanoparticles (Pd/N-C) has been developed by carbonizing a palladium dimethylglyoximate complex. The as-synthesized Pd/N-C has been exfoliated as a fuel cell catalyst by studying the electro-oxidation of methanol and formic acid. The material synthesized at 400 °C,namely, Pd/N-C-400,exhibitssuperior mass activity and stability among catalysts synthesized under different carbonization temperaturesbetween300 and 500 °C. The unique 1D porous structure in Pd/N-C-400 helps better electron transport at the electrode surface, which eventually leads to about five times better catalytic activity and about two times higher stability than that of commercial Pd/C. Thus, our designed sacrificial metal-organic templatedirected pathway becomes a promising technique for Pd/N-C synthesis with superior catalytic performances. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

The biosynthesis of palladium nanoparticles by antioxidants in Gardenia jasminoides Ellis: long lifetime nanocatalysts for p-nitrotoluene hydrogenation

Energy Technology Data Exchange (ETDEWEB)

Jia Lishan; Zhang Qian; Li Qingbiao; Song Hao, E-mail: jials@xmu.edu.c [Department of Chemical and Biochemical Engineering, College of Chemistry and Chemical Engineering, Xiamen University, Xiamen 361005 (China); Key Laboratory for Chemistry and Biochemical Engineering, Department of Chemical and Biochemical Engineering, College of Chemistry and Chemical Engineering, Xiamen University, Xiamen 361005 (China); Key Laboratory for Chemical Biology of Fujian Province, Xiamen University, Xiamen 361005 (China)

2009-09-23

Gardenia jasminoides Ellis' water crude extract was used for the bioreduction of palladium chloride in this paper. The UV-vis spectrum, x-ray diffraction spectrum measurement, the Fourier transform infrared spectroscopy and TEM technique confirmed the formation of palladium nanoparticles and identified antioxidants including geniposide, chlorogenic acid, crocins and crocetin were reducing and stabilizing agents for synthesizing palladium nanoparticles in water crude extract. The particle size and dispersity were temperature-dependent. The particle sizes ranged from 3 to 5 nm and revealed the best dispersity at 70 {sup 0}C. Catalytic performance of the biosynthetic Pd nanoparticles with good dispersity was investigated by hydrogenation of p-nitrotoluene. The catalysts showed a conversion of 100% under conditions of 5 MPa, 150 {sup 0}C for 2 h. The selectivity of p-methyl-cyclohexylamine achieved 26.3%. The catalyst was recycled five times with no agglomeration and maintained activity, which was attributed to the appropriate protection of the antioxidants. On the basis of the study, it appears to be a new promising biosynthetic nanocatalyst for the development of an industrial process.

The biosynthesis of palladium nanoparticles by antioxidants in Gardenia jasminoides Ellis: long lifetime nanocatalysts for p-nitrotoluene hydrogenation

Science.gov (United States)

Jia, Lishan; Zhang, Qian; Li, Qingbiao; Song, Hao

2009-09-01

Gardenia jasminoides Ellis' water crude extract was used for the bioreduction of palladium chloride in this paper. The UV-vis spectrum, x-ray diffraction spectrum measurement, the Fourier transform infrared spectroscopy and TEM technique confirmed the formation of palladium nanoparticles and identified antioxidants including geniposide, chlorogenic acid, crocins and crocetin were reducing and stabilizing agents for synthesizing palladium nanoparticles in water crude extract. The particle size and dispersity were temperature-dependent. The particle sizes ranged from 3 to 5 nm and revealed the best dispersity at 70 °C. Catalytic performance of the biosynthetic Pd nanoparticles with good dispersity was investigated by hydrogenation of p-nitrotoluene. The catalysts showed a conversion of 100% under conditions of 5 MPa, 150 °C for 2 h. The selectivity of p-methyl-cyclohexylamine achieved 26.3%. The catalyst was recycled five times with no agglomeration and maintained activity, which was attributed to the appropriate protection of the antioxidants. On the basis of the study, it appears to be a new promising biosynthetic nanocatalyst for the development of an industrial process.

hydrogel membrane as electrolyte for direct borohydride fuel cells

Indian Academy of Sciences (India)

A direct borohydride fuel cell (DBFC) employing a poly (vinyl alcohol) hydrogel membrane electrolyte (PHME) is reported. The DBFC employs an AB5 Misch metal alloy as anode and a goldplated stainless steel mesh as cathode in conjunction with aqueous alkaline solution of sodium borohydride as fuel and aqueous ...

Immobilized Palladium Nanoparticles on Zirconium Carboxy-Aminophosphonates Nanosheets as an Efficient Recoverable Heterogeneous Catalyst for Suzuki–Miyaura and Heck Coupling

Directory of Open Access Journals (Sweden)

Vadym Kozell

2017-06-01

Full Text Available Zirconium phosphate glycine diphosphonate nanosheets (ZPGly have been used as support for the preparation of solid palladium nanoparticles, namely Pd@ZPGly. Thanks to the presence of carboxy-aminophosponate groups on the layer surface, ZPGly-based materials were able to stabilize a high amount of palladium (up to 22 wt % also minimizing the amount of metal leached in the final products of representative important cross-coupling processes selected for proving the catalysts’ efficiency. The catalytic systems have been fully characterized and used in low amounts (0.1 mol % in the Suzuki–Miyaura and Heck cross-couplings. Moreover, the protocols were optimized for the use of recoverable azeotropic mixtures (aq. EtOH 96% or aq. CH3CN 84%, respectively and in the flow procedure allowing one to isolate the final pure products, without any purification step, with very low residual palladium content and with a very low waste production.

Complexation-Induced Phase Separation: Preparation of Metal-Rich Polymeric Membranes

KAUST Repository

Villalobos Vazquez de la Parra, Luis Francisco

2017-08-01

applications: (i) catalytic membranes containing palladium nanoparticles (PdNPs), (ii) antibiofouling tight-UF membranes containing silver chloride (AgCl) crystals, and (iii) palladiumrich PBI hollow fibers for H2 recovery.

Polystyrene-Supported Acyclic Diaminocarbene Palladium Complexes in Sonogashira Cross-Coupling: Stability vs. Catalytic Activity

Directory of Open Access Journals (Sweden)

Vladimir N. Mikhaylov

2018-04-01

Full Text Available Two types of immobilized on the amino-functionalized polystyrene-supported acyclic diaminocarbene palladium complexes (ADC-PdII are investigated under Sonogashira cross-coupling conditions. Depending on substituents in the diaminocarbene fragment immobilized ADC-PdII, systems are found to have different catalytic activity and stability regarding Pd-leaching. PdII-diaminocarbenes possessing protons at both nitrogen atoms smoothly decompose into Pd0-containing species providing a catalytic “cocktail system” with high activity and ability to reuse within nine runs. Polymer-supported palladium (II complex bearing NBn–Ccarbene–NH-moiety exhibits greater stability while noticeably lower activity under Sonogashira cross-coupling. Four molecular ADC-PdII complexes are also synthesized and investigated with the aim of confirming proposed base-promoted pathway of ADC-PdII conversion through carbodiimide into an active Pd0 forms.

The impact of surface composition on Tafel kinetics leading to enhanced electrochemical insertion of hydrogen in palladium

Science.gov (United States)

Dmitriyeva, Olga; Hamm, Steven C.; Knies, David L.; Cantwell, Richard; McConnell, Matt

2018-05-01

Our previous work experimentally demonstrated the enhancement of electrochemical hydrogen insertion into palladium by modifying the chemical composition of the cathode surface with Pb, Pt and Bi, referred to as surface promoters. The experiment demonstrated that an optimal combination of the surface promoters led to an increase in hydrogen fugacity of more than three orders of magnitude, while maintaining the same current density. This manuscript discusses the application of Density Functional Theory (DFT) to elucidate the thermodynamics and kinetics of observed enhancement of electrochemical hydrogen insertion into palladium. We present theoretical simulations that: (1) establish the elevation of hydrogen's chemical potential on Pb and Bi surfaces to enhance hydrogen insertion, (2) confirm the increase of a Tafel activation barrier that results in a decrease of the reaction rate at the given hydrogen overpotential, and (3) explain why the surface promoter's coverage needs to be non-uniform, namely to allow hydrogen insertion into palladium bulk while simultaneously locking hydrogen below the surface (the corking effect). The discussed DFT-based method can be used for efficient scanning of different material configurations to design a highly effective hydrogen storage system.

Performance of ethanol electro-oxidation on Ni-Cu alloy nanowires through composition modulation.

Science.gov (United States)

Tian, Xi-Ke; Zhao, Xiao-Yu; Zhang, Li-de; Yang, Chao; Pi, Zhen-Bang; Zhang, Su-Xin

2008-05-28

To reduce the cost of the catalyst for direct ethanol fuel cells and improve its catalytic activity, highly ordered Ni-Cu alloy nanowire arrays have been fabricated successfully by differential pulse current electro-deposition into the pores of a porous anodic alumina membrane (AAMs). The energy dispersion spectrum, scanning and transmission electron microscopy were utilized to characterize the composition and morphology of the Ni-Cu alloy nanowire arrays. The results reveal that the nanowires in the array are uniform, well isolated and parallel to each other. The catalytic activity of the nanowire electrode arrays for ethanol oxidation was tested and the binary alloy nanowire array possesses good catalytic activity for the electro-oxidation of ethanol. The performance of ethanol electro-oxidation was controlled by varying the Cu content in the Ni-Cu alloy and the Ni-Cu alloy nanowire electrode shows much better stability than the pure Ni one.

Performance of ethanol electro-oxidation on Ni-Cu alloy nanowires through composition modulation

International Nuclear Information System (INIS)

Tian Xike; Zhao Xiaoyu; Yang Chao; Pi Zhenbang; Zhang Lide; Zhang Suxin

2008-01-01

To reduce the cost of the catalyst for direct ethanol fuel cells and improve its catalytic activity, highly ordered Ni-Cu alloy nanowire arrays have been fabricated successfully by differential pulse current electro-deposition into the pores of a porous anodic alumina membrane (AAMs). The energy dispersion spectrum, scanning and transmission electron microscopy were utilized to characterize the composition and morphology of the Ni-Cu alloy nanowire arrays. The results reveal that the nanowires in the array are uniform, well isolated and parallel to each other. The catalytic activity of the nanowire electrode arrays for ethanol oxidation was tested and the binary alloy nanowire array possesses good catalytic activity for the electro-oxidation of ethanol. The performance of ethanol electro-oxidation was controlled by varying the Cu content in the Ni-Cu alloy and the Ni-Cu alloy nanowire electrode shows much better stability than the pure Ni one

Hydrodechlorination of Tetrachloromethane over Palladium Catalysts Supported on Mixed MgF2-MgO Carriers

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Magdalena Bonarowska

2016-11-01

Full Text Available Pd/MgO, Pd/MgF2 and Pd/MgO-MgF2 catalysts were investigated in the reaction of CCl4 hydrodechlorination. All the catalysts deactivated in time on stream, but the degree of deactivation varied from catalyst to catalyst. The MgF2-supported palladium with relatively large metal particles appeared the best catalyst, characterized by good activity and selectivity to C2-C5 hydrocarbons. Investigation of post-reaction catalyst samples allowed to find several details associated with the working state of hydrodechlorination catalysts. The role of support acidity was quite complex. On the one hand, a definite, although not very high Lewis acidity of MgF2 is beneficial for shaping high activity of palladium catalysts. The MgO-MgF2 support characterized by stronger Lewis acidity than MgF2 contributes to very good catalytic activity for a relatively long reaction period (~5 h but subsequent neutralization of stronger acid centers (by coking eliminates them from the catalyst. On the other hand, the role of acidity evolution, which takes place when basic supports (like MgO are chlorided during HdCl reactions, is difficult to assess because different events associated with distribution of chlorided support species, leading to partial or even full blocking of the surface of palladium, which plays the role of active component in HdCl reactions.

Effect of pH on the spontaneous synthesis of palladium nanoparticles on reduced graphene oxide

International Nuclear Information System (INIS)

Zhang, Xiaorui; Ooki, Wataru; Kosaka, Yoshinori R.; Okonogi, Akinori; Marzun, Galina; Wagener, Philipp; Barcikowski, Stephan; Kondo, Takahiro; Nakamura, Junji

2016-01-01

Highlights: • Palladium metal nanoparticles were spontaneously formed on reduced graphene oxide (rGO) via a redox reaction in H_2O. • The amount of Pd deposited on rGO was affected by pH. • The amount of oxygen-containing functional groups in rGO was increased with the deposition of palladium. • The importance of redox potential in spontaneous deposition was demonstrated by an experiment with Zn, Ni, Pt, Pd, etc.. • The spontaneous redox deposition method is facile, environmentally friendly, and needs no external reducing agents. - Abstract: Palladium (Pd) nanoparticles were spontaneously deposited on reduced graphene oxide (rGO) without any external reducing agents. The prepared Pd/rGO composites were then characterized by X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS). Spontaneous deposition occurred because of a redox reaction between the Pd precursor and rGO, which involved reduction of bivalent Pd to metallic Pd"0 and oxidation of the sp"2 carbon of rGO to oxygen-containing functional groups. The amount of Pd deposited on rGO varied with pH, and this was attributed to electrostatic interactions between the Pd precursor and rGO based on the results of zeta potential measurements. The importance of the redox reaction in the spontaneous deposition was demonstrated in the experiment with Zn, Ni, Cu, Ag, Pt, Pd, and Au.

Effect of pH on the spontaneous synthesis of palladium nanoparticles on reduced graphene oxide

Energy Technology Data Exchange (ETDEWEB)

Zhang, Xiaorui [Faculty of Pure and Applied Sciences, University of Tsukuba, 1-1-1 Tennodai, Tsukuba, Ibaraki 305-8573 (Japan); Ooki, Wataru; Kosaka, Yoshinori R.; Okonogi, Akinori [Graduate School of Pure and Applied Sciences, University of Tsukuba, 1-1-1 Tennodai, Tsukuba, Ibaraki 305-8573 (Japan); Marzun, Galina; Wagener, Philipp; Barcikowski, Stephan [Technical Chemistry I and Center for Nanointegration Duisburg-Essen (CENIDE), University of Duisburg-Essen, Universitaetsstrasse 7, D-45141 Essen (Germany); NanoEnergieTechnikZentrum (NETZ), University of Duisburg-Essen, Carl-Benz-Strasse 199, D-47057 Duisburg (Germany); Kondo, Takahiro [Faculty of Pure and Applied Sciences, University of Tsukuba, 1-1-1 Tennodai, Tsukuba, Ibaraki 305-8573 (Japan); Tsukuba Research Center for Interdisciplinary Materials Science (TIMS) & Center for Integrated Research in Fundamental Science and Engineering (CiRfSE), University of Tsukuba, 1-1-1 Tennodai, 305-8573 (Japan); Nakamura, Junji, E-mail: nakamura@ims.tsukuba.ac.jp [Faculty of Pure and Applied Sciences, University of Tsukuba, 1-1-1 Tennodai, Tsukuba, Ibaraki 305-8573 (Japan); Tsukuba Research Center for Interdisciplinary Materials Science (TIMS) & Center for Integrated Research in Fundamental Science and Engineering (CiRfSE), University of Tsukuba, 1-1-1 Tennodai, 305-8573 (Japan)

2016-12-15

Highlights: • Palladium metal nanoparticles were spontaneously formed on reduced graphene oxide (rGO) via a redox reaction in H{sub 2}O. • The amount of Pd deposited on rGO was affected by pH. • The amount of oxygen-containing functional groups in rGO was increased with the deposition of palladium. • The importance of redox potential in spontaneous deposition was demonstrated by an experiment with Zn, Ni, Pt, Pd, etc.. • The spontaneous redox deposition method is facile, environmentally friendly, and needs no external reducing agents. - Abstract: Palladium (Pd) nanoparticles were spontaneously deposited on reduced graphene oxide (rGO) without any external reducing agents. The prepared Pd/rGO composites were then characterized by X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS). Spontaneous deposition occurred because of a redox reaction between the Pd precursor and rGO, which involved reduction of bivalent Pd to metallic Pd{sup 0} and oxidation of the sp{sup 2} carbon of rGO to oxygen-containing functional groups. The amount of Pd deposited on rGO varied with pH, and this was attributed to electrostatic interactions between the Pd precursor and rGO based on the results of zeta potential measurements. The importance of the redox reaction in the spontaneous deposition was demonstrated in the experiment with Zn, Ni, Cu, Ag, Pt, Pd, and Au.

RAPID AND SENSITIVE DETERMINATION OF PALLADIUM USING HOMOGENEOUS LIQUID-LIQUID MICROEXTRACTION VIA FLOTATION ASSISTANCE FOLLOWED BY GRAPHITE FURNACE ATOMIC ABSORPTION SPECTROMETRY

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Mohammad Rezaee

2015-05-01

Full Text Available A method for the determination of trace amounts of palladium was developed using homogeneous liquid-liquid microextraction via flotation assistance (HLLME-FA followed by graphite furnace atomic absorption spectrometry (GFAAS. Ammonium pyrrolidine dithiocarbamate (APDC was used as a complexing agent. This was applied to determine palladium in three types of water samples. In this study, a special extraction cell was designed to facilitate collection of the low-density solvent extraction. No centrifugation was required in this procedure. The water sample solution was added to the extraction cell which contained an appropriate mixture of extraction and homogeneous solvents. By using air flotation, the organic solvent was collected at the conical part of the designed cell. Parameters affecting extraction efficiency were investigated and optimized. Under the optimum conditions, the calibration graph was linear in the range of 1.0-200 µg L-1 with a limit of detection of 0.3 µg L-1. The performance of the method was evaluated for the extraction and determination of palladium in water samples and satisfactory results were obtained. In order to verify the accuracy of the approach, the standard addition method was applied for the determination of palladium in spiked synthetic samples and satisfactory results were obtained.

Direct determination of thermodynamic activities of gold in the systems gold-palladium and gold-silver-palladium