WorldWideScience

Sample records for catalyzed hydrogen generation

  1. Noble metal catalyzed hydrogen generation from formic acid in nitrite-containing simulated nuclear waste media

    International Nuclear Information System (INIS)

    The Hanford Waste Vitrification Plant (HWVP) is being designed by the U.S. Department of Energy to immobilize high-level nuclear waste. Simulants for the HWVP feed containing the major nonradioactive components Al, Cd, Fe, Mn, Nd, Ni, Si, Zr, Na, CO32-, NO3- and NO2- were used as media to evaluate the stability of formic acid towards hydrogen evolution by the reaction HCO2H→H2+/CO2 catalyzed by the noble metals Ru, Rh, and/or Pd found in significant quantities in uranium fission products. Small-scale experiments using 40-50 mL of feed simulant in closed glass reactors (250-550 mL total volume) at 80-100 degree C were used to study the effect of nitrite and nitrate ion on the catalytic activities of the noble metals for formic acid decomposition. Reactions were monitored using gas chromatography to analyze the CO2, H2, NO, and N2O in the gas phase as a function of time. Rhodium, which was introduced as soluble RhCl3.3H2O, was found to be the most active catalyst for hydrogen generation from formic acid above nearly 80 degree C in the presence of nitrite ion in accord with earlier observations. The apparent homogeneous nature of the nitrite-promoted Rh-catalyzed formic acid decomposition is consistent with the approximate pseudo-first-order dependence of the hydrogen production rate on Rh concentration. 24 refs., 7 figs., 2 tabs

  2. Hydrogen evolution catalyzed by cobaloximes.

    Science.gov (United States)

    Dempsey, Jillian L; Brunschwig, Bruce S; Winkler, Jay R; Gray, Harry B

    2009-12-21

    Natural photosynthesis uses sunlight to drive the conversion of energy-poor molecules (H(2)O, CO(2)) to energy-rich ones (O(2), (CH(2)O)(n)). Scientists are working hard to develop efficient artificial photosynthetic systems toward the "Holy Grail" of solar-driven water splitting. High on the list of challenges is the discovery of molecules that efficiently catalyze the reduction of protons to H(2). In this Account, we report on one promising class of molecules: cobalt complexes with diglyoxime ligands (cobaloximes). Chemical, electrochemical, and photochemical methods all have been utilized to explore proton reduction catalysis by cobaloxime complexes. Reduction of a Co(II)-diglyoxime generates a Co(I) species that reacts with a proton source to produce a Co(III)-hydride. Then, in a homolytic pathway, two Co(III)-hydrides react in a bimolecular step to eliminate H(2). Alternatively, in a heterolytic pathway, protonation of the Co(III)-hydride produces H(2) and Co(III). A thermodynamic analysis of H(2) evolution pathways sheds new light on the barriers and driving forces of the elementary reaction steps involved in proton reduction by Co(I)-diglyoximes. In combination with experimental results, this analysis shows that the barriers to H(2) evolution along the heterolytic pathway are, in most cases, substantially greater than those of the homolytic route. In particular, a formidable barrier is associated with Co(III)-diglyoxime formation along the heterolytic pathway. Our investigations of cobaloxime-catalyzed H(2) evolution, coupled with the thermodynamic preference for a homolytic route, suggest that the rate-limiting step is associated with formation of the hydride. An efficient water splitting device may require the tethering of catalysts to an electrode surface in a fashion that does not inhibit association of Co(III)-hydrides. PMID:19928840

  3. Catalyzed borohydrides for hydrogen storage

    Science.gov (United States)

    Au, Ming

    2012-02-28

    A hydrogen storage material and process is provided in which alkali borohydride materials are created which contain effective amounts of catalyst(s) which include transition metal oxides, halides, and chlorides of titanium, zirconium, tin, and combinations of the various catalysts. When the catalysts are added to an alkali borodydride such as a lithium borohydride, the initial hydrogen release point of the resulting mixture is substantially lowered. Additionally, the hydrogen storage material may be rehydrided with weight percent values of hydrogen at least about 9 percent.

  4. Palladium catalyzed hydrogenation of bio-oils and organic compounds

    Science.gov (United States)

    Elliott, Douglas C.; Hu, Jianli; Hart, Todd R.; Neuenschwander, Gary G.

    2008-09-16

    The invention provides palladium-catalyzed hydrogenations of bio-oils and certain organic compounds. Experimental results have shown unexpected and superior results for palladium-catalyzed hydrogenations of organic compounds typically found in bio-oils.

  5. Chitosan catalyzes hydrogen evolution at mercury electrodes

    Czech Academy of Sciences Publication Activity Database

    Paleček, Emil; Římánková, Ludmila

    2014-01-01

    Roč. 44, JUL2014 (2014), s. 59-62. ISSN 1388-2481 R&D Projects: GA ČR(CZ) GAP301/11/2055 Institutional support: RVO:68081707 Keywords : Chitosan * Glucosamine-containing polymers * Catalytic hydrogen evolution Subject RIV: BO - Biophysics Impact factor: 4.847, year: 2014

  6. Electrochemical Hydrogen Peroxide Generator

    Science.gov (United States)

    Tennakoon, Charles L. K.; Singh, Waheguru; Anderson, Kelvin C.

    2010-01-01

    Two-electron reduction of oxygen to produce hydrogen peroxide is a much researched topic. Most of the work has been done in the production of hydrogen peroxide in basic media, in order to address the needs of the pulp and paper industry. However, peroxides under alkaline conditions show poor stabilities and are not useful in disinfection applications. There is a need to design electrocatalysts that are stable and provide good current and energy efficiencies to produce hydrogen peroxide under acidic conditions. The innovation focuses on the in situ generation of hydrogen peroxide using an electrochemical cell having a gas diffusion electrode as the cathode (electrode connected to the negative pole of the power supply) and a platinized titanium anode. The cathode and anode compartments are separated by a readily available cation-exchange membrane (Nafion 117). The anode compartment is fed with deionized water. Generation of oxygen is the anode reaction. Protons from the anode compartment are transferred across the cation-exchange membrane to the cathode compartment by electrostatic attraction towards the negatively charged electrode. The cathode compartment is fed with oxygen. Here, hydrogen peroxide is generated by the reduction of oxygen. Water may also be generated in the cathode. A small amount of water is also transported across the membrane along with hydrated protons transported across the membrane. Generally, each proton is hydrated with 3-5 molecules. The process is unique because hydrogen peroxide is formed as a high-purity aqueous solution. Since there are no hazardous chemicals or liquids used in the process, the disinfection product can be applied directly to water, before entering a water filtration unit to disinfect the incoming water and to prevent the build up of heterotrophic bacteria, for example, in carbon based filters. The competitive advantages of this process are: 1. No consumable chemicals are needed in the process. The only raw materials

  7. Hydrogen storage and generation system

    Science.gov (United States)

    Dentinger, Paul M.; Crowell, Jeffrey A. W.

    2010-08-24

    A system for storing and generating hydrogen generally and, in particular, a system for storing and generating hydrogen for use in an H.sub.2/O.sub.2 fuel cell. The hydrogen storage system uses the beta particles from a beta particle emitting material to degrade an organic polymer material to release substantially pure hydrogen. In a preferred embodiment of the invention, beta particles from .sup.63Ni are used to release hydrogen from linear polyethylene.

  8. Iron-, Cobalt-, and Nickel-Catalyzed Asymmetric Transfer Hydrogenation and Asymmetric Hydrogenation of Ketones.

    Science.gov (United States)

    Li, Yan-Yun; Yu, Shen-Luan; Shen, Wei-Yi; Gao, Jing-Xing

    2015-09-15

    Chiral alcohols are important building blocks in the pharmaceutical and fine chemical industries. The enantioselective reduction of prochiral ketones catalyzed by transition metal complexes, especially asymmetric transfer hydrogenation (ATH) and asymmetric hydrogenation (AH), is one of the most efficient and practical methods for producing chiral alcohols. In both academic laboratories and industrial operations, catalysts based on noble metals such as ruthenium, rhodium, and iridium dominated the asymmetric reduction of ketones. However, the limited availability, high price, and toxicity of these critical metals demand their replacement with abundant, nonprecious, and biocommon metals. In this respect, the reactions catalyzed by first-row transition metals, which are more abundant and benign, have attracted more and more attention. As one of the most abundant metals on earth, iron is inexpensive, environmentally benign, and of low toxicity, and as such it is a fascinating alternative to the precious metals for catalysis and sustainable chemical manufacturing. However, iron catalysts have been undeveloped compared to other transition metals. Compared with the examples of iron-catalyzed asymmetric reduction, cobalt- and nickel-catalyzed ATH and AH of ketones are even seldom reported. In early 2004, we reported the first ATH of ketones with catalysts generated in situ from iron cluster complex and chiral PNNP ligand. Since then, we have devoted ourselves to the development of ATH and AH of ketones with iron, cobalt, and nickel catalysts containing novel chiral aminophosphine ligands. In our study, the iron catalyst containing chiral aminophosphine ligands, which are expected to control the stereochemistry at the metal atom, restrict the number of possible diastereoisomers, and effectively transfer chiral information, are successful catalysts for enantioselective reduction of ketones. Among these novel chiral aminophosphine ligands, 22-membered macrocycle P2N4

  9. Catalyzed hydrogenation of nitrogen and ethylene on metal (Fe, Pt) single crystal surfaces and effects of coadsorption: A sum frequency generation vibrational spectroscopy study

    Energy Technology Data Exchange (ETDEWEB)

    Westerberg, Staffan Per Gustav

    2004-12-15

    High-pressure catalytic reactions and associated processes, such as adsorption have been studied on a molecular level on single crystal surfaces. Sum Frequency Generation (SFG) vibrational spectroscopy together with Auger Electron Spectroscopy (AES), Temperature Programmed Desorption (TPD) and Gas Chromatography (GC) were used to investigate the nature of species on catalytic surfaces and to measure the catalytic reaction rates. Special attention has been directed at studying high-pressure reactions and in particular, ammonia synthesis in order to identify reaction intermediates and the influence of adsorbates on the surface during reaction conditions. The adsorption of gases N{sub 2}, H{sub 2}, O{sub 2} and NH{sub 3} that play a role in ammonia synthesis have been studied on the Fe(111) crystal surface by sum frequency generation vibrational spectroscopy using an integrated Ultra-High Vacuum (UHV)/high-pressure system. SFG spectra are presented for the dissociation intermediates, NH{sub 2} ({approx}3325 cm{sup -1}) and NH ({approx}3235 cm{sup -1}) under high pressure of ammonia (200 Torr) on the clean Fe(111) surface. Addition of 0.5 Torr of oxygen to 200 Torr of ammonia does not significantly change the bonding of dissociation intermediates to the surface. However, it leads to a phase change of nearly 180{sup o} between the resonant and non-resonant second order non-linear susceptibility of the surface, demonstrated by the reversal of the SFG spectral features. Heating the surface in the presence of 200 Torr ammonia and 0.5 Torr oxygen reduces the oxygen coverage, which can be seen from the SFG spectra as another relative phase change of 180{sup o}. The reduction of the oxide is also supported by Auger electron spectroscopy. The result suggests that the phase change of the spectral features could serve as a sensitive indicator of the chemical environment of the adsorbates.

  10. Solar hydrogen generator

    Science.gov (United States)

    Sebacher, D. I.; Sabol, A. P. (Inventor)

    1977-01-01

    An apparatus, using solar energy to manufacture hydrogen by dissociating water molecules into hydrogen and oxygen molecules is described. Solar energy is concentrated on a globe containing water thereby heating the water to its dissociation temperature. The globe is pervious to hydrogen molecules permitting them to pass through the globe while being essentially impervious to oxygen molecules. The hydrogen molecules are collected after passing through the globe and the oxygen molecules are removed from the globe.

  11. Development and industrial application of catalyzer for low-temperature hydrogenation hydrolysis of Claus tail gas

    Directory of Open Access Journals (Sweden)

    Honggang Chang

    2015-10-01

    Full Text Available With the implementation of more strict national environmental protection laws, energy conservation, emission reduction and clean production will present higher requirements for sulfur recovery tail gas processing techniques and catalyzers. As for Claus tail gas, conventional hydrogenation catalyzers are gradually being replaced by low-temperature hydrogenation catalyzers. This paper concentrates on the development of technologies for low-temperature hydrogenation hydrolysis catalyzers, preparation of such catalyzers and their industrial application. In view of the specific features of SO2 hydrogenation and organic sulfur hydrolysis during low-temperature hydrogenation, a new technical process involving joint application of hydrogenation catalyzers and hydrolysis catalyzers was proposed. In addition, low-temperature hydrogenation catalyzers and low-temperature hydrolysis catalyzers suitable for low-temperature conditions were developed. Joint application of these two kinds of catalyzers may reduce the inlet temperatures in the conventional hydrogenation reactors from 280 °C to 220 °C, at the same time, hydrogenation conversion rates of SO2 can be enhanced to over 99%. To further accelerate the hydrolysis rate of organic sulfur, the catalyzers for hydrolysis of low-temperature organic sulfur were developed. In lab tests, the volume ratio of the total sulfur content in tail gas can be as low as 131 × 10−6 when these two kinds of catalyzers were used in a proportion of 5:5 in volumes. Industrial application of these catalyzers was implemented in 17 sulfur recovery tail gas processing facilities of 15 companies. As a result, Sinopec Jinling Petrochemical Company had outstanding application performances with a tail gas discharging rate lower than 77.9 mg/m3 and a total sulfur recovery of 99.97%.

  12. Hydrogen Generation From Electrolysis

    Energy Technology Data Exchange (ETDEWEB)

    Steven Cohen; Stephen Porter; Oscar Chow; David Henderson

    2009-03-06

    Small-scale (100-500 kg H2/day) electrolysis is an important step in increasing the use of hydrogen as fuel. Until there is a large population of hydrogen fueled vehicles, the smaller production systems will be the most cost-effective. Performing conceptual designs and analyses in this size range enables identification of issues and/or opportunities for improvement in approach on the path to 1500 kg H2/day and larger systems. The objectives of this program are to establish the possible pathways to cost effective larger Proton Exchange Membrane (PEM) water electrolysis systems and to identify areas where future research and development efforts have the opportunity for the greatest impact in terms of capital cost reduction and efficiency improvements. System design and analysis was conducted to determine the overall electrolysis system component architecture and develop a life cycle cost estimate. A design trade study identified subsystem components and configurations based on the trade-offs between system efficiency, cost and lifetime. Laboratory testing of components was conducted to optimize performance and decrease cost, and this data was used as input to modeling of system performance and cost. PEM electrolysis has historically been burdened by high capital costs and lower efficiency than required for large-scale hydrogen production. This was known going into the program and solutions to these issues were the focus of the work. The program provided insights to significant cost reduction and efficiency improvement opportunities for PEM electrolysis. The work performed revealed many improvement ideas that when utilized together can make significant progress towards the technical and cost targets of the DOE program. The cell stack capital cost requires reduction to approximately 25% of today’s technology. The pathway to achieve this is through part count reduction, use of thinner membranes, and catalyst loading reduction. Large-scale power supplies are available

  13. Recent advances in osmium-catalyzed hydrogenation and dehydrogenation reactions.

    Science.gov (United States)

    Chelucci, Giorgio; Baldino, Salvatore; Baratta, Walter

    2015-02-17

    CONSPECTUS: A current issue in metal-catalyzed reactions is the search for highly efficient transition-metal complexes affording high productivity and selectivity in a variety of processes. Moreover, there is also a great interest in multitasking catalysts that are able to efficiently promote different organic transformations by careful switching of the reaction parameters, such as temperature, solvent, and cocatalyst. In this context, osmium complexes have shown the ability to catalyze efficiently different types of reactions involving hydrogen, proving at the same time high thermal stability and simple synthesis. In the catalytic reduction of C═X (X = O, N) bonds by both hydrogenation (HY) and transfer hydrogenation (TH) reactions, the most interest has been focused on homogeneous systems based on rhodium, iridium, and in particular ruthenium catalysts, which have proved to catalyze chemo- and stereoselective hydrogenations with remarkable efficiency. By contrast, osmium catalysts have received much less attention because they are considered less active on account of their slower ligand exchange kinetics. Thus, this area remained almost neglected until recent studies refuted these prejudices. The aim of this Account is to highlight the impressive developments achieved over the past few years by our and other groups on the design of new classes of osmium complexes and their applications in homogeneous catalytic reactions involving the hydrogenation of carbon-oxygen and carbon-nitrogen bonds by both HY and TH reactions as well as in alcohol deydrogenation (DHY) reactions. The work described in this Account demonstrates that osmium complexes are emerging as powerful catalysts for asymmetric and non-asymmetric syntheses, showing a remarkably high catalytic activity in HY and TH reactions of ketones, aldehydes, imines, and esters as well in DHY reactions of alcohols. Thus, for instance, the introduction of ligands with an NH function, possibly in combination with a

  14. Hydrogenation of unsaturated hydrocarbons catalyzed by palladium complexes. [Phenylacetylene

    Energy Technology Data Exchange (ETDEWEB)

    Levkovskii, Y.S.; Ryutina, N.M.; Shmidt, F.K.

    1980-06-01

    Hydrogenation of unsaturated hydrocarbons catalyzed by palladium complexes obtained by reducing Pd(II) stearate or acetylacetonate (AcAc) with triethylaluminum was studied at 30/sup 0/C in toluene solutions. Hydrogenation of phenylacetylene in the presence of Pd(AcAc)/sub 2/ and Al(C/sub 2/H/sub 5/)/sub 3/ at 0.005 mole/l. Pd and 2:1 Al/Pd occurred much more rapidly than in the absence of Al(C/sub 2/H/sub 5/)/sub 3/ and gave ethylbenzene as the only product. Subsequent addition of organic phosphines, e.g., P(C/sub 6/H/sub 5/)/sub 3/ or P(C/sub 4/H/sub 9/)/sub 3/, shifted the reaction toward styrene, which was obtained with up to 98% selectivity at 4:1 P/Pd. P(C/sub 4/H/sub 9/)/sub 3/ also strongly increased the reaction rate. Addition of phosphines before Al(C/sub 2/H/sub 5/)/sub 3/ produced systems with low activities. Hydrogenation of isoprene in the presence of Pd(II) compounds and Al (C/sub 2/H/sub 5/) occurred at as low as 10/sup 0/C and gave isopentane and methylbutene isomers. The selectivity for the latter at 95% isoprene conversion was increased from 84 to 99.8% by the addition of phosphines to 6:1 P/Pd. Phosphines also had an activating effect which increased in the order P(C/sub 6/H/sub 5/)/sub 3/ < P(C/sub 4/H/sub 9/)/sub 3/ < P(C/sub 6/H/sub 11/)/sub 3/.

  15. NOx-Catalyzed Gas-Phase Activation of Methane:the Formation of Hydrogen

    Institute of Scientific and Technical Information of China (English)

    Chaoxian Xiao; Zhen Yan; Yuan Kou

    2003-01-01

    NOx-catalyzed oxidation of methane without a solid catalyst was investigated, and a hydrogen selectivity of 27% was obtained with an overall methane conversion of 34% and a free O2 concentration of 1.7% at 700 ℃.

  16. Magnetic Mesoporous Palladium Catalyzed Selective Hydrogenation of Sunflower Oil.

    Science.gov (United States)

    Liu, Wei; Tian, Fei; Yu, Jingjing; Bi, Yanlan

    2016-05-01

    In this paper, a novel magnetic mesoporous Pd catalyst is used to catalyse selective hydrogenation of sunflower oil at a mild temperature of 50°C. Effects of reaction temperature, stirring speed, time, catalyst loading and hydrogen pressure on the reaction activity, trans fatty acid (TFA) and stearic acid formation were studied. Under the condition of 3.2 mg Pd/100 g oil, 50°C, 1300 rpm stirring speed and 19.0 atm of H2, the lowest amount of TFA generated during the reaction (IV = 80) was 14.9 ± 0.4% while 11.4 ± 0.4% of stearic acid was produced. And this magnetic Pd-catalyst can be reused easily for at least six times without significant catalyst deactivation, the amount of TFA almost remained unchanged. Moreover, this Pd-catalyst shows a good magnetic separation, which provides a potential method for the facile oil modification. PMID:27086993

  17. Safe Hydrogen Generation by Nuclear HTR

    International Nuclear Information System (INIS)

    Several concepts of new high temperature nuclear reactors are designed to generate electricity and hydrogen. Hydrogen processes envisaged here are sulfur iodine thermo-chemical process and high temperature electrolysis. Proximity of hydrogen generation is a safety challenge for nuclear reactor. This paper describes prevention and protection against hydrogen hazards as a function of inventories and type of operation of the processes. This study is important for the designers because long distance between reactor and hydrogen facility induces difficult technological equipment. (authors)

  18. Fuel cell using a hydrogen generation system

    Science.gov (United States)

    Dentinger, Paul M.; Crowell, Jeffrey A. W.

    2010-10-19

    A system is described for storing and generating hydrogen and, in particular, a system for storing and generating hydrogen for use in an H.sub.2/O.sub.2 fuel cell. The hydrogen storage system uses beta particles from a beta particle emitting material to degrade an organic polymer material to release substantially pure hydrogen. In a preferred embodiment of the invention, beta particles from .sup.63Ni are used to release hydrogen from linear polyethylene.

  19. Hydrogen generation in tru waste transportation packages

    Energy Technology Data Exchange (ETDEWEB)

    Anderson, B; Sheaffer, M K; Fischer, L E

    2000-03-27

    This document addresses hydrogen generation in TRU waste transportation packages. The potential sources of hydrogen generation are summarized with a special emphasis on radiolysis. After defining various TRU wastes according to groupings of material types, bounding radiolytic G-values are established for each waste type. Analytical methodologies are developed for prediction of hydrogen gas concentrations for various packaging configurations in which hydrogen generation is due to radiolysis. Representative examples are presented to illustrate how analytical procedures can be used to estimate the hydrogen concentration as a function of time. Methodologies and examples are also provided to show how the time to reach a flammable hydrogen concentration in the innermost confinement layer can be estimated. Finally, general guidelines for limiting the hydrogen generation in the payload and hydrogen accumulation in the innermost confinement layer are described.

  20. Characteristics of hydrogen evolution and oxidation catalyzed by Desulfovibrio caledoniensis biofilm on pyrolytic graphite electrode

    International Nuclear Information System (INIS)

    Highlights: → The sulphate-reducing bacteria (SRB) have the ability to catalyze the hydrogen evolution and oxidation on pyrolytic graphite electrode. → The SRB biofilm decreases the overpotential and electron transfer resistance by the CV and EIS detection. → The SRB biofilm can transfer electrons to the 0.24 V polarized pyrolytic graphite electrode and the maximum current is 0.035 mA, which is attributed to SRB catalyzed hydrogen oxidation. → The SRB biofilm also can obtain electron from the -0.61 V polarized PGE to catalyze the hydrogen evolution. - Abstract: Hydrogenase, an important electroactive enzyme of sulphate-reducing bacteria (SRB), has been discovered having the capacity to connect its activity to solid electrodes by catalyzing hydrogen evolution and oxidation. However, little attention has been paid to similar electroactive characteristics of SRB. In this study, the electroactivities of pyrolytic graphite electrode (PGE) coated with SRB biofilm were investigated. Two corresponding redox peaks were observed by cyclic voltammetry detection, which were related to the hydrogen evolution and oxidation. Moreover, the overpotential for the reactions decreased by about 0.2 V in the presence of the SRB biofilm. When the PGE coated with the SRB biofilm was polarized at 0.24 V (vs. SHE), an oxidation current related to the hydrogen oxidation was found. The SRB biofilm was able to obtain electrons from the -0.61 V (vs. SHE) polarized PGE to form hydrogen, and the electron transfer resistance also decreased with the formation of SRB biofilm, as measured by the non-destructive electrochemical impendence spectroscopy detection. It was concluded that the hydrogen evolution and oxidation was an important way for the electron transfer between SRB biofilm and solid electrode in anaerobic environment.

  1. Destabilized and catalyzed borohydride for reversible hydrogen storage

    Science.gov (United States)

    Mohtadi, Rana F.; Nakamura, Kenji; Au, Ming; Zidan, Ragaiy

    2012-01-31

    A process of forming a hydrogen storage material, including the steps of: providing a first material of the formula M(BH.sub.4).sub.X, where M is an alkali metal or an alkali earth metal, providing a second material selected from M(AlH.sub.4).sub.x, a mixture of M(AlH.sub.4).sub.x and MCl.sub.x, a mixture of MCl.sub.x and Al, a mixture of MCl.sub.x and AlH.sub.3, a mixture of MH.sub.x and Al, Al, and AlH.sub.3. The first and second materials are combined at an elevated temperature and at an elevated hydrogen pressure for a time period forming a third material having a lower hydrogen release temperature than the first material and a higher hydrogen gravimetric density than the second material.

  2. Hydrogen Evolution Catalyzed by Cobalt Diimine-Dioxime Complexes

    OpenAIRE

    Kaeffer, Nicolas; Chavarot-Kerlidou, Murielle; Artero, Vincent

    2015-01-01

    Mimicking photosynthesis and producing solar fuels is an appealing way to store the huge amount of renewable energy from the sun in a durable and sustainable way. Hydrogen production through water splitting has been set as a first-ranking target for artificial photosynthesis. Pursuing that goal requires the development of efficient and stable catalytic systems, only based on earth abundant elements, for the reduction of protons from water to molecular hydrogen. Cobalt complexes based on glyox...

  3. Enantioselective Rh-catalyzed hydrogenation of N-formyl dehydroamino esters with monodentate phosphoramidite ligands

    NARCIS (Netherlands)

    Panella, L; Aleixandre, AM; Kruidhof, GJ; Robertus, J; Feringa, BL; de Vries, JG; Minnaard, AJ; Aleixandre, Alicia Marco; Kruidhof, Gerlof J.; Feringa, Bernard

    2006-01-01

    Enantioselectivities up to > 99% ee were achieved in the rhodium-catalyzed asymmetric hydrogenation of N-formyl dehydroamino esters using morrodentate phosphoramidites as chiral ligands. The substrates were synthesized by condensation of methyl isocyanoacetate with a range of aldehydes and with cycl

  4. Solar Fuels. Photocatalytic Hydrogen Generation

    OpenAIRE

    Kamat, Prashant V.; Bisquert, Juan

    2013-01-01

    The necessity for developing clean energy technology has led to the surge in renewable energy research. A major effort is in discovering new approaches for producing transportable fuels. Hydrogen, which possesses the highest energy density (120 MJ/kg) known for any fuel and no carbon footprint, is regarded as the leading contender for meeting future fuel needs. The term Hydrogen Economy is often referred collectively to the topics of production, storage, and transport of hydrogen.

  5. Polylysine-catalyzed hydrogen evolution at mercury electrodes

    Czech Academy of Sciences Publication Activity Database

    Živanovic, Marko; Aleksić, M.; Ostatná, Veronika; Doneux, Thomas; Paleček, Emil

    2010-01-01

    Roč. 22, 17-18 (2010), s. 2064-2070. ISSN 1040-0397 R&D Projects: GA AV ČR(CZ) KJB100040901; GA MŠk(CZ) ME09038; GA MŠk(CZ) LC06035 Grant ostatní: GA AV ČR(CZ) KAN400310651 Institutional research plan: CEZ:AV0Z50040507; CEZ:AV0Z50040702 Keywords : catalytic hydrogen evolution * constant current chronopotentiometric stripping * polylysine Subject RIV: BO - Biophysics Impact factor: 2.721, year: 2010

  6. Gold-catalyzed oxidation of substituted phenols by hydrogen peroxide

    KAUST Repository

    Cheneviere, Yohan

    2010-10-20

    Gold nanoparticles deposited on inorganic supports are efficient catalysts for the oxidation of various substituted phenols (2,6-di-tert-butyl phenol and 2,3,6-trimethyl phenol) with aqueous hydrogen peroxide. By contrast to more conventional catalysts such as Ti-containing mesoporous silicas, which convert phenols to the corresponding benzoquinones, gold nanoparticles are very selective to biaryl compounds (3,3′,5,5′-tetra-tert-butyl diphenoquinone and 2,2′,3,3′,5,5′-hexamethyl-4,4′- biphenol, respectively). Products yields and selectivities depend on the solvent used, the best results being obtained in methanol with yields >98%. Au offers the possibility to completely change the selectivity in the oxidation of substituted phenols and opens interesting perspectives in the clean synthesis of biaryl compounds for pharmaceutical applications. © 2010 Elsevier B.V. All rights reserved.

  7. Hydrogen dilution effect on microstructure of Si thin film grown by catalyzer enhanced chemical vapor deposition

    International Nuclear Information System (INIS)

    The effect of hydrogen dilution on microstructure of in situ polycrystalline Si (poly-Si) films grown by catalyzer-enhanced chemical vapor deposition (CECVD) has been investigated by using transmission electron microscopy (TEM) and transmission electron diffraction (TED) analysis. It was shown that the increase of the hydrogen dilution ratio resulted in transition of microstructure of Si thin film from amorphous to polycrystalline in CECVD at low substrate temperature (∼80 deg. C). These results indicate that the CECVD technique is a promising candidate to grow high-quality in situ polycrystalline Si films on glass or a flexible substrate for low-temperature poly-Si (LTPS) and flexible displays

  8. Hydrogen dilution effect on microstructure of Si thin film grown by catalyzer enhanced chemical vapor deposition

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Han-Ki [School of Advanced Materials and Systems Engineering, Kumoh National Institute of Technology (KIT), 1 Yangho-dong, Gumi, Gyeongbuk, 730-701 (Korea, Republic of)]. E-mail: hkkim@kumoh.ac.kr

    2006-12-15

    The effect of hydrogen dilution on microstructure of in situ polycrystalline Si (poly-Si) films grown by catalyzer-enhanced chemical vapor deposition (CECVD) has been investigated by using transmission electron microscopy (TEM) and transmission electron diffraction (TED) analysis. It was shown that the increase of the hydrogen dilution ratio resulted in transition of microstructure of Si thin film from amorphous to polycrystalline in CECVD at low substrate temperature ({approx}80 deg. C). These results indicate that the CECVD technique is a promising candidate to grow high-quality in situ polycrystalline Si films on glass or a flexible substrate for low-temperature poly-Si (LTPS) and flexible displays.

  9. Iron- and Cobalt-Catalyzed Alkene Hydrogenation: Catalysis with Both Redox-Active and Strong Field Ligands.

    Science.gov (United States)

    Chirik, Paul J

    2015-06-16

    The hydrogenation of alkenes is one of the most impactful reactions catalyzed by homogeneous transition metal complexes finding application in the pharmaceutical, agrochemical, and commodity chemical industries. For decades, catalyst technology has relied on precious metal catalysts supported by strong field ligands to enable highly predictable two-electron redox chemistry that constitutes key bond breaking and forming steps during turnover. Alternative catalysts based on earth abundant transition metals such as iron and cobalt not only offer potential environmental and economic advantages but also provide an opportunity to explore catalysis in a new chemical space. The kinetically and thermodynamically accessible oxidation and spin states may enable new mechanistic pathways, unique substrate scope, or altogether new reactivity. This Account describes my group's efforts over the past decade to develop iron and cobalt catalysts for alkene hydrogenation. Particular emphasis is devoted to the interplay of the electronic structure of the base metal compounds and their catalytic performance. First generation, aryl-substituted pyridine(diimine) iron dinitrogen catalysts exhibited high turnover frequencies at low catalyst loadings and hydrogen pressures for the hydrogenation of unactivated terminal and disubstituted alkenes. Exploration of structure-reactivity relationships established smaller aryl substituents and more electron donating ligands resulted in improved performance. Second generation iron and cobalt catalysts where the imine donors were replaced by N-heterocyclic carbenes resulted in dramatically improved activity and enabled hydrogenation of more challenging unactivated, tri- and tetrasubstituted alkenes. Optimized cobalt catalysts have been discovered that are among the most active homogeneous hydrogenation catalysts known. Synthesis of enantiopure, C1 symmetric pyridine(diimine) cobalt complexes have enabled rare examples of highly enantioselective

  10. Two-chamber hydrogen generation and application: access to pressurized deuterium gas.

    Science.gov (United States)

    Modvig, Amalie; Andersen, Thomas L; Taaning, Rolf H; Lindhardt, Anders T; Skrydstrup, Troels

    2014-06-20

    Hydrogen and deuterium gas were produced and directly applied in a two-chamber system. These gaseous reagents were generated by the simple reaction of metallic zinc with HCl in water for H2 and DCl in deuterated water for D2. The setup proved efficient in classical Pd-catalyzed reductions of ketones, alkynes, alkenes, etc. in near-quantitative yields. The method was extended to the synthesis and isotope labeling of quinoline and 1,2,3,4-tetrahydroquinoline derivatives. Finally, CX-546 and Olaparib underwent efficient Ir-catalyzed hydrogen isotope exchange reactions. PMID:24870212

  11. Ph(i-PrO)SiH2: An Exceptional Reductant for Metal-Catalyzed Hydrogen Atom Transfers.

    Science.gov (United States)

    Obradors, Carla; Martinez, Ruben M; Shenvi, Ryan A

    2016-04-13

    We report the discovery of an outstanding reductant for metal-catalyzed radical hydrofunctionalization reactions. Observations of unexpected silane solvolysis distributions in the HAT-initiated hydrogenation of alkenes reveal that phenylsilane is not the kinetically preferred reductant in many of these transformations. Instead, isopropoxy(phenyl)silane forms under the reaction conditions, suggesting that alcohols function as important silane ligands to promote the formation of metal hydrides. Study of its reactivity showed that isopropoxy(phenyl)silane is an exceptionally efficient stoichiometric reductant, and it is now possible to significantly decrease catalyst loadings, lower reaction temperatures, broaden functional group tolerance, and use diverse, aprotic solvents in iron- and manganese-catalyzed hydrofunctionalizations. As representative examples, we have improved the yields and rates of alkene reduction, hydration, hydroamination, and conjugate addition. Discovery of this broadly applicable, chemoselective, and solvent-versatile reagent should allow an easier interface with existing radical reactions. Finally, isotope-labeling experiments rule out the alternative hypothesis of hydrogen atom transfer from a redox-active β-diketonate ligand in the HAT step. Instead, initial HAT from a metal hydride to directly generate a carbon-centered radical appears to be the most reasonable hypothesis. PMID:26984323

  12. GREEN CATALYZED OXIDATION OF HYDROCARBONS IN ALTERNATIVE SOLVENT SYSTEMS GENERATED BY PARIS II

    Science.gov (United States)

    Green Catalyzed Oxidation of Hydrocarbons in Alternative Solvent Systems Generated by PARIS IIMichael A. Gonzalez*, Thomas M. Becker, and Paul F. Harten; Sustainable Technology Division, Office of Research and Development; United States Environmental Protection Agency, 26...

  13. Off-board hydrogen recharging of nanonickel-catalyzed magnesium hydrides : nanomaterials and process

    Energy Technology Data Exchange (ETDEWEB)

    Wronski, Z.S. [Natural Resources Canada, Ottawa, ON (Canada). CANMET Energy Technology Centre, Hydrogen Fuel Cells and Transportation Energy Group; Czujko, T.; Varin, R.A. [Waterloo Univ., Waterloo, ON (Canada). Waterloo Inst. of Sustainable Energy; Baksa, S.; Paserin, V. [IncoVale, Sheridan Park, Mississauga, ON (Canada)

    2009-07-01

    There are many technical challenges in finding suitable materials for onboard reversible hydrogen storage in vehicles, particularly regarding the amount of heat released on recharging of reversible hydrides. Although requirements for off-board recharging could be less restrictive, they still require a prohibitive combination of high temperature and pressure. Magnesium, magnesium-nickel, and magnesium-iron metal mixtures and spent hydrides can be charged and recharged off-board at ambient temperatures in ball-mill reactor cylinders that are supplied with low-pressure hydrogen. Inco-nanonickel-catalyzed Mg and Mg-Fe hydrides, currently under joint development between the Waterloo Institute of Sustainable Energy (WISE) at the University of Waterloo and the HyFATE Nanomaterials Laboratory in Ottawa, are mechanically rechargeable via milling in hydrogen, and deliver 6 and 4 wt per cent hydrogen at about 275 degrees C and 1 bar hydrogen pressure, respectively. This paper noted that although lightweight materials based on magnesium may be almost ready for mechanical off-board recharging for niche applications in stationary, mobile and portable applications, any consideration for off-board recharging for onboard hydrogen storage in fuel cell cars would require a big shift from current goals set by the United States Department of Energy.

  14. Efficient Method for the Determination of the Activation Energy of the Iodide-Catalyzed Decomposition of Hydrogen Peroxide

    Science.gov (United States)

    Sweeney, William; Lee, James; Abid, Nauman; DeMeo, Stephen

    2014-01-01

    An experiment is described that determines the activation energy (E[subscript a]) of the iodide-catalyzed decomposition reaction of hydrogen peroxide in a much more efficient manner than previously reported in the literature. Hydrogen peroxide, spontaneously or with a catalyst, decomposes to oxygen and water. Because the decomposition reaction is…

  15. Hydrogen Generation from Plasmatron Reforming Ethanol

    Institute of Scientific and Technical Information of China (English)

    YOU Fu-bing; HU You-ping; LI Ge-sheng; GAO Xiao-hong

    2006-01-01

    Hydrogen generation through plasmatron reforming of ethanol has been carried out in a dielectric barrier discharge (DBD) reactor. The reforming of pure ethanol and mixtures of ethanol-water have been studied. The gas chromatography (GC) analysis has shown that in all conditions the reforming yield was H2, CO, CH4 and CO2 as the main products, and with little C2* . The hydrogen-rich gas can be used as fuel for gasoline engine and other applications.

  16. Environmentally Benign Oxidation of Some Organic Sulfides with 34% Hydrogen Peroxide Catalyzed by Simple Heteropolyoxometalates

    Institute of Scientific and Technical Information of China (English)

    TAYEBEE,Reza; ALIZADEH,Moharnmad Hassan

    2007-01-01

    An environmentally benign oxygenation protocol was developed for selective oxidation of some types of aromatic and aliphatic sulfides in good to excellent yields utilizing 34% hydrogen peroxide catalyzed by simple heteropolyoxometalates in normal drinking water at room temperature. The catalysts could be recovered and reused for at least seven reaction cycles under the described reaction conditions without considerable loss of reactivity. This procedure introduced a new insight into the use of simple heteropolyanions as recoverable catalysts for the oxidation of organic sulfides by an environmentally acceptable protocol.

  17. HYDROGENATION OF PHENOL AND CRESOLS CATALYZED BY CHITOSAN SUPPORTED PALLADIUM COMPLEX AT MILD CONDITIONS

    Institute of Scientific and Technical Information of China (English)

    TANG Liming; HUANG Meiyu; JIANG Yingyan

    1996-01-01

    A natural polymer catalyst, silica-supported chitosan palladium complex (abbr. as SiO2-CS-Pd) was found to catalyze the hydrogenation of phenol and cresols to corresponding cyclohexanones in high yield and 100% selectivity at 70℃ and 1.01325 × 105 Pa mild conditions. N/Pd molar ratio in the complex, temperature and solvents have much influence on the reaction. The reactivity order of reactants was found to be: phenol >m->p->ocresol. The catalyst is stable during the reaction and could be repeatedly used for several times without much decrease in its catalytic activity.

  18. A new type of hydrogen generator-HHEG (high-compressed hydrogen energy generator)

    International Nuclear Information System (INIS)

    'Full text:' We have developed a new type of hydrogen generator named HHEG (High-compressed Hydrogen Energy Generator). HHEG can produce 35 MPa high-compressed hydrogen for fuel cell vehicle without any mechanical compressor. HHEG is a kind of PEM(proton exchange membrane)electrolysis. It was well known that compressed hydrogen could be generated by water electrolysis. However, the conventional electrolysis could not generate 35 MPa or higher pressure that is required for fuel cell vehicle, because electrolysis cell stack is destroyed in such high pressure. In HHEG, the cell stack is put in high-pressure vessel and the pressure difference of oxygen and hydrogen that is generated by the cell stack is always kept at nearly zero by an automatic compensator invented by Mitsubishi Corporation. The cell stack of HHEG is not so special one, but it is not broken under such high pressure, because the automatic compensator always offsets the force acting on the cell stack. Hydrogen for fuel cell vehicle must be produce by no emission energy such as solar and atomic power. These energies are available as electricity. So, water electrolysis is the only way of producing hydrogen fuel. Hydrogen fuel is also 35 MPa high-compressed hydrogen and will become 70 MPa in near future. But conventional mechanical compressor is not useful for such high pressure hydrogen fuel, because of the short lifetime and high power consumption. Construction of hydrogen station network is indispensable in order to come into wide use of fuel cell vehicles. For such network contraction, an on-site type hydrogen generator is required. HHEG can satisfy above these requirements. So we can conclude that HHEG is the only way of realizing the hydrogen economy. (author)

  19. Multi-enzyme catalyzed processes: Next generation biocatalysis

    DEFF Research Database (Denmark)

    Andrade Santacoloma, Paloma de Gracia; Sin, Gürkan; Gernaey, Krist;

    2011-01-01

    Biocatalysis has been attracting increasing interest in recent years. Nevertheless, most studies concerning biocatalysis have been carried out using single enzymes (soluble or immobilized). Currently, multiple enzyme mixtures are attractive for the production of many compounds at an industrial...... level. In this review, a classification of multienzyme-catalyzed processes is proposed. Special emphasis is placed on the description of multienzyme ex-vivo systems where several reactions are carried out by a combination of enzymes acting outside the cell. Furthermore, reaction and process...... considerations for mathematical modeling are discussed for the specific case where the synthetic reactions are carried out in a single reactor, the so-called multienzyme ‘in-pot’ process. In addition, options for multienzyme ‘in-pot’ process improvements via process engineering and enzyme immobilization...

  20. Isomerization of Olefins Triggered by Rhodium-Catalyzed C–H Bond Activation: Control of Endocyclic β-Hydrogen Elimination**

    OpenAIRE

    Yip, Stephanie Y Y; Aïssa, Christophe

    2015-01-01

    Five-membered metallacycles are typically reluctant to undergo endocyclic β-hydrogen elimination. The rhodium-catalyzed isomerization of 4-pentenals into 3-pentenals occurs through this elementary step and cleavage of two C–H bonds, as supported by deuterium-labeling studies. The reaction proceeds without decarbonylation, leads to trans olefins exclusively, and tolerates other olefins normally prone to isomerization. Endocyclic β-hydrogen elimination can also be controlled in an enantiodiverg...

  1. Modeling of hydrogen/deuterium dynamics and heat generation on palladium nanoparticles for hydrogen storage and solid-state nuclear fusion.

    Science.gov (United States)

    Tanabe, Katsuaki

    2016-01-01

    We modeled the dynamics of hydrogen and deuterium adsorbed on palladium nanoparticles including the heat generation induced by the chemical adsorption and desorption, as well as palladium-catalyzed reactions. Our calculations based on the proposed model reproduce the experimental time-evolution of pressure and temperature with a single set of fitting parameters for hydrogen and deuterium injection. The model we generated with a highly generalized set of formulations can be applied for any combination of a gas species and a catalytic adsorbent/absorbent. Our model can be used as a basis for future research into hydrogen storage and solid-state nuclear fusion technologies. PMID:27441240

  2. Suppression of superoxide anion generation catalyzed by xanthine oxidase with alkyl caffeates and the scavenging activity.

    Science.gov (United States)

    Masuoka, Noriyoshi; Kubo, Isao

    2016-05-01

    Alkyl caffeates are strong antioxidants and inhibitors of xanthine oxidase. However, it is unclear about the effect of caffeic acid and alkyl caffeates on superoxide anion (O2(-)) generation catalyzed by xanthine oxidase. Effects of caffeic acid and alkyl caffeates on the uric acid formation and O2(-) generation catalyzed by xanthine oxidase were analyzed. The scavenging activities of 1,1-diphenyl-2-picryhydrazyl (DPPH) radical and O2(-) generated with phenazine methosulfate (PMS) and NADH were examined. Caffeic acid derivatives equally suppressed O2(-) generation, and the suppression is stronger than inhibition of xanthine oxidase. Scavenging activity of O2(-) is low compared to the suppression of O2(-) generation. Suppression of O2(-) generation catalyzed by xanthine oxidase with caffeic acid derivatives was not due to enzyme inhibition or O2(-) scavenging but due to the reduction of xanthine oxidase molecules. Alkyl caffeates are effective inhibitors of uric acid and O2(-) catalyzed by xanthine oxidase as well as antioxidants for edible oil. PMID:26940252

  3. PipPhos and MorfPhos : Privileged monodentate phosphoramidite ligands for rhodium-catalyzed asymmetric hydrogenation

    NARCIS (Netherlands)

    Bernsmann, Heiko; van den Berg, M; Hoen, Robert; Minnaard, AJ; Mehler, G; Reetz, MT; De Vries, JG; Feringa, BL

    2005-01-01

    A library of 20 monodentate phosphoramidite ligands has been prepared and applied in rhodium-catalyzed asymmetric hydrogenation. This resulted in the identification of two ligands, PipPhos and MorfPhos, that afford excellent and in several cases unprecedented enantioselectivities in the hydrogenatio

  4. Monte Carlo Fitting Of Data From Muon Catalyzed Fusion Experiments In Solid Hydrogen

    Directory of Open Access Journals (Sweden)

    M. Filipowicz

    2008-01-01

    Full Text Available Applying the classical chi-square fitting procedure for multiparameter systems is in somecases extremely difficult due to the lack of an analytical expression for the theoretical functionsdescribing the system. This paper presents an analysis procedure for experimental datausing theoretical functions generated by Monte Carlo method, each corresponding to definitevalues of the minimization parameters. It was applied for the E742 experiment (TRIUMF,Vancouver, Canada data analysis with the aim to analyze data from Muon Catalyzed Fusionexperiments (extraction muonic atom scattering parameters and parameters of pd fusion inpdμ molecule.

  5. ESR ST study of hydroxyl radical generation in wet peroxide system catalyzed by heterogeneous ruthenium

    NARCIS (Netherlands)

    Rokhina, E.V.; Golovina, E.A.; As, van H.; Virkutyte, J.

    2009-01-01

    Ru-based catalysts gained popularity because of their applicability for a variety of processes, including carbon monoxide oxidation, wet air catalytic oxidation and wastewater treatment. The focus of a current study was generation of hydroxyl radicals in the wet peroxide system catalyzed by heteroge

  6. Treatment of four biorefractory contaminants in soils using catalyzed hydrogen peroxide

    International Nuclear Information System (INIS)

    The treatment of soil with pentachlorophenol, trifluralin, hexadecane, and dieldrin using catalyzed hydrogen peroxide [H2O and iron(II)] was investigated in a soil of low development with organic C ranging from 2,000 mg kg-1 to 16,000 mg kg-1. Soil treatment was conducted at pH 3 with 240 and 400 mg L-1 iron additions and 120,000 mg L-1 H2O2. Pentachlorophenol and trifluralin degradation rates decreased as a function of soil organic C content. However, soil organic C had no effect on the degradation rates of dieldrin and hexadecane. In addition, the four contaminant degraded at equal rates with soil containing organic C > 10,000 mg kg-1. The ratio of first-order rate constant for contaminant degradation to hydrogen peroxide consumption was used as an empirical measure of treatment efficiency. These ratios were sensitive to both the soil and organic C content and to the concentration of iron added during treatment. The efficiency ratios were highest for treatment with no iron addition; these data suggest that iron minerals and H2O2 provide a system in which Fenton-like oxidations pentachlorophenol was evaluated in goethite-, hematite-, and magnetite-silica sand at pH 3. Pentachlorophenol was degraded in the mineral-silica sand systems

  7. Hanford Waste Vitrification Plant hydrogen generation

    International Nuclear Information System (INIS)

    The most promising method for the disposal of highly radioactive nuclear wastes is a vitrification process in which the wastes are incorporated into borosilicate glass logs, the logs are sealed into welded stainless steel canisters, and the canisters are buried in suitably protected burial sites for disposal. The purpose of the research supported by the Hanford Waste Vitrification Plant (HWVP) project of the Department of Energy through Battelle Pacific Northwest Laboratory (PNL) and summarized in this report was to gain a basic understanding of the hydrogen generation process and to predict the rate and amount of hydrogen generation during the treatment of HWVP feed simulants with formic acid. The objectives of the study were to determine the key feed components and process variables which enhance or inhibit the.production of hydrogen. Information on the kinetics and stoichiometry of relevant formic acid reactions were sought to provide a basis for viable mechanistic proposals. The chemical reactions were characterized through the production and consumption of the key gaseous products such as H2. CO2, N20, NO, and NH3. For this mason this research program relied heavily on analyses of the gases produced and consumed during reactions of the HWVP feed simulants with formic acid under various conditions. Such analyses, used gas chromatographic equipment and expertise at the University of Georgia for the separation and determination of H2, CO, CO2, N2, N2O and NO

  8. Prion-derived copper-binding peptide fragments catalyze the generation of superoxide anion in the presence of aromatic monoamines

    Directory of Open Access Journals (Sweden)

    Tomonori Kawano

    2007-01-01

    Full Text Available Objectives: Studies have proposed two opposing roles for copper-bound forms of prion protein (PrP as an anti-oxidant supporting the neuronal functions and as a pro-oxidant leading to neurodegenerative process involving the generation of reactive oxygen species. The aim of this study is to test the hypothesis in which putative copper-binding peptides derived from PrP function as possible catalysts for monoamine-dependent conversion of hydrogen peroxide to superoxide in vitro. Materials and methods: Four peptides corresponding to the copper (II-binding motifs in PrP were synthesized and used for analysis of peptide-catalyzed generation of superoxide in the presence of Cu (II and other factors naturally present in the neuronal tissues. Results: Among the Cu-binding peptides tested, the amino acid sequence corresponding to the Cu-binding site in the helical region was shown to be the most active for superoxide generation in the presence of Cu(II, hydrogen peroxide and aromatic monoamines, known precursors or intermediates of neurotransmitters. Among monoamines tested, three compounds namely phenylethylamine, tyramine and benzylamine were shown to be good substrates for superoxide-generating reactions by the Cu-bound helical peptide. Conclusions: Possible roles for these reactions in development of prion disease were suggested.

  9. Engineering analysis of requirements for a muon-catalyzed fusion electrical-generating system

    International Nuclear Information System (INIS)

    Engineering analyses have been conducted to investigate baseline requirements for the muon catalysis efficiency necessary (fusions per muon) to render a muon-catalyzed fusion, electrical power-generating station feasible. Catalysis efficiency requirements are examined in terms of energy break-even (scientific, engineering, commercial) definitions and the efficiencies of various components in the overall system. Benefits associated with recycling the scattered portions of the muon-producing accelerator beam, accelerator thermal energy loss, and various thermal losses in the system are addressed. These engineering analyses delineate technical areas where research and development may be needed to improve overall economic viability of muon-catalyzed fusion

  10. Iron-catalyzed generation of pentane from irradiated erythrocyte membranes

    International Nuclear Information System (INIS)

    Data presented here show that pentane is generated from human erthyrocyte membranes upon irradiation (800 Gy, cobalt-60) as measured by gas chromatography. Malondialdehyde production, measured by the thiobarbituric acid assay, accompanied pentane evolution. Pentane evolution can be modified by the addition of iron and various protective agents. Irradiation in the presence of 0.1 mN Fe2+ (ferrious ammonium sulfate) increased pentane formation from 9 to 34 pmol/mg membrane protein. Addition before irradiation of hyroxyl radical scavengers, such as benzoate (5mM), decreased pentane production from 34 to 14 pmol. Addition of WR-2721 resulted in a decrease in pentane to 15 pmol. Pentane production was greatly diminished by the presence of catalase or superoxide dismutase during irradiation. These studies suggest that oxygen radical species that are induced by ionizing radiation can affect mammalian cell membranes and this effect can be enhanced by iron, probably through catalysis of a Haber-Weiss type reaction

  11. HIGH EFFICIENCY GENERATION OF HYDROGEN FUELS USING NUCLEAR POWER

    Energy Technology Data Exchange (ETDEWEB)

    BROWN,LC; BESENBRUCH,GE; LENTSCH,RD; SCHULTZ,KR; FUNK,JF; PICKARD,PS; MARSHALL,AC; SHOWALTER,SK

    2003-06-01

    fossil fuels has trace contaminants (primarily carbon monoxide) that are detrimental to precious metal catalyzed fuel cells, as is now recognized by many of the world's largest automobile companies. Thermochemical hydrogen will not contain carbon monoxide as an impurity at any level. Electrolysis, the alternative process for producing hydrogen using nuclear energy, suffers from thermodynamic inefficiencies in both the production of electricity and in electrolytic parts of the process. The efficiency of electrolysis (electricity to hydrogen) is currently about 80%. Electric power generation efficiency would have to exceed 65% (thermal to electrical) for the combined efficiency to exceed the 52% (thermal to hydrogen) calculated for one thermochemical cycle. Thermochemical water-splitting cycles have been studied, at various levels of effort, for the past 35 years. They were extensively studied in the late 70s and early 80s but have received little attention in the past 10 years, particularly in the U.S. While there is no question about the technical feasibility and the potential for high efficiency, cycles with proven low cost and high efficiency have yet to be developed commercially. Over 100 cycles have been proposed, but substantial research has been executed on only a few. This report describes work accomplished during a three-year project whose objective is to ''define an economically feasible concept for production of hydrogen, by nuclear means, using an advanced high temperature nuclear reactor as the energy source.'' The emphasis of the first phase was to evaluate thermochemical processes which offer the potential for efficient, cost-effective, large-scale production of hydrogen from water in which the primary energy input is high temperature heat from an advanced nuclear reactor and to select one (or, at most three) for further detailed consideration. During Phase 1, an exhaustive literature search was performed to locate all cycles

  12. Water co-catalyzed selective dehydrogenation of methanol to formaldehyde and hydrogen

    Science.gov (United States)

    Shan, Junjun; Lucci, Felicia R.; Liu, Jilei; El-Soda, Mostafa; Marcinkowski, Matthew D.; Allard, Lawrence F.; Sykes, E. Charles H.; Flytzani-Stephanopoulos, Maria

    2016-08-01

    The non-oxidative dehydrogenation of methanol to formaldehyde is considered a promising method to produce formaldehyde and clean hydrogen gas. Although Cu-based catalysts have an excellent catalytic activity in the oxidative dehydrogenation of methanol, metallic Cu is commonly believed to be unreactive for the dehydrogenation of methanol in the absence of oxygen adatoms or oxidized copper. Herein we show that metallic Cu can catalyze the dehydrogenation of methanol in the absence of oxygen adatoms by using water as a co-catalyst both under realistic reaction conditions using silica-supported PtCu nanoparticles in a flow reactor system at temperatures below 250 °C, and in ultra-high vacuum using model PtCu(111) catalysts. Adding small amounts of isolated Pt atoms into the Cu surface to form PtCu single atom alloys (SAAs) greatly enhances the dehydrogenation activity of Cu. Under the same reaction conditions, the yields of formaldehyde from PtCu SAA nanoparticles are more than one order of magnitude higher than on the Cu nanoparticles, indicating a significant promotional effect of individual, isolated Pt atoms. Moreover, this study also shows the unexpected role of water in the activation of methanol. Water, a catalyst for methanol dehydrogenation at low temperatures, becomes a reactant in the methanol steam reforming reactions only at higher temperatures over the same metal catalyst.

  13. Interconversion between formate and hydrogen carbonate by tungsten-containing formate dehydrogenase-catalyzed mediated bioelectrocatalysis

    Directory of Open Access Journals (Sweden)

    Kento Sakai

    2015-09-01

    Full Text Available We have focused on the catalytic properties of tungsten-containing formate dehydrogenase (FoDH1 from Methylobacterium extorquens AM1 to construct a bioelectrochemical interconversion system between formate (HCOO− and hydrogen carbonate (HCO3−. FoDH1 catalyzes both of the HCOO oxidation and the HCO3− reduction with several artificial dyes. The bi-molecular reaction rate constants between FoDH1 and the artificial electron acceptors and NAD+ (as the natural electron acceptor show the property called a linear free energy relationship (LFER, indicating that FoDH1 would have no specificity to NAD+. Similar LFER is also observed for the catalytic reduction of HCO3−. The reversible reaction between HCOO− and HCO3− through FoDH1 has been realized on cyclic voltammetry by using methyl viologen (MV as a mediator and by adjusting pH from the thermodynamic viewpoint. Potentiometric measurements have revealed that the three redox couples, MV2+/MV·−+, HCOO−/HCO3−, FoDH1 (ox/red, reach an equilibrium in the bulk solution when the two-way bioelectrocatalysis proceeds in the presence of FoDH1 and MV. The steady-state voltammograms with two-way bioelectrocatalytic properties are interpreted on a simple model by considering the solution equilibrium.

  14. Tryptophanase-Catalyzed l-Tryptophan Synthesis from d-Serine in the Presence of Diammonium Hydrogen Phosphate

    OpenAIRE

    Fujii Noriko; Haruka Ozaki; Takeshi Saito; Akihiko Shimada

    2009-01-01

    Tryptophanase, an enzyme with extreme absolute stereospecificity for optically active stereoisomers, catalyzes the synthesis of L-tryptophan from L-serine and indole through a β-substitution mechanism of the ping-pong type, and has no activity on D-serine. We previously reported that tryptophanase changed its stereospecificity to degrade D-tryptophan in highly concentrated diammonium hydrogen phosphate, (NH4)2HPO4 solution. The present study provided the same stereospecific change seen in the...

  15. Generating single-photon catalyzed coherent states with quantum-optical catalysis

    Science.gov (United States)

    Xu, Xue-xiang; Yuan, Hong-chun

    2016-07-01

    We theoretically generate single-photon catalyzed coherent states (SPCCSs) by means of quantum-optical catalysis based on the beam splitter (BS) or the parametric amplifier (PA). These states are obtained in one of the BS (or PA) output channels if a coherent state and a single-photon Fock state are present in two input ports and a single photon is registered in the other output port. The success probabilities of the detection (also the normalization factors) are discussed, which is different for BS and PA catalysis. In addition, we prove that the generated states catalyzed by BS and PA devices are actually the same quantum states after analyzing photon number distribution of the SPCCSs. The quantum properties of the SPCCSs, such as sub-Poissonian distribution, anti-bunching effect, quadrature squeezing effect, and the negativity of the Wigner function are investigated in detail. The results show that the SPCCSs are non-Gaussian states with an abundance of nonclassicality.

  16. Method and system for storing and generating hydrogen

    Science.gov (United States)

    Kindler, Andrew (Inventor); Narayanan, Sri R. (Inventor); Huang, Yuhong (Inventor)

    2011-01-01

    A method and system for storing and generating hydrogen. The method comprises generating hydrogen and heat from the reaction of a metal or metal compound with water. The heat generated from this reaction may then be converted to other forms of energy such as by passing the heat through a thermal electric device to recover electrical energy for storage in a battery. In an alternative and preferred embodiment, the heat is used to drive additional reactions for generating more hydrogen and is preferably used to drive an endothermic dehydrogenation reaction resulting in increased hydrogen generation and consumption of the heat.

  17. Nanostructured, complex hydride systems for hydrogen generation

    Directory of Open Access Journals (Sweden)

    Robert A. Varin

    2015-02-01

    Full Text Available Complex hydride systems for hydrogen (H2 generation for supplying fuel cells are being reviewed. In the first group, the hydride systems that are capable of generating H2 through a mechanical dehydrogenation phenomenon at the ambient temperature are discussed. There are few quite diverse systems in this group such as lithium alanate (LiAlH4 with the following additives: nanoiron (n-Fe, lithium amide (LiNH2 (a hydride/hydride system and manganese chloride MnCl2 (a hydride/halide system. Another hydride/hydride system consists of lithium amide (LiNH2 and magnesium hydride (MgH2, and finally, there is a LiBH4-FeCl2 (hydride/halide system. These hydride systems are capable of releasing from ~4 to 7 wt.% H2 at the ambient temperature during a reasonably short duration of ball milling. The second group encompasses systems that generate H2 at slightly elevated temperature (up to 100 °C. In this group lithium alanate (LiAlH4 ball milled with the nano-Fe and nano-TiN/TiC/ZrC additives is a prominent system that can relatively quickly generate up to 7 wt.% H2 at 100 °C. The other hydride is manganese borohydride (Mn(BH42 obtained by mechano-chemical activation synthesis (MCAS. In a ball milled (2LiBH4 + MnCl2 nanocomposite, Mn(BH42 co-existing with LiCl can desorb ~4.5 wt.% H2 at 100 °C within a reasonable duration of dehydrogenation. Practical application aspects of hydride systems for H2 generation/storage are also briefly discussed.

  18. Catalyzed Nano-Framework Stablized High Density Reversible Hydrogen Storage Systems

    Energy Technology Data Exchange (ETDEWEB)

    Tang, Xia [value too long for type character varying(50); Opalka, Susanne M.; Mosher, Daniel A; Laube, Bruce L; Brown, Ronald J; Vanderspurt, Thomas H; Arsenault, Sarah; Wu, Robert; Strickler, Jamie; Ronnebro, Ewa; Boyle, Tim; Cordaro, Joseph

    2010-06-30

    A wide range of high capacity on-board rechargeable material candidates have exhibited non-ideal behavior related to irreversible hydrogen discharge / recharge behavior, and kinetic instability or retardation. This project addresses these issues by incorporating solvated and other forms of complex metal hydrides, with an emphasis on borohydrides, into nano-scale frameworks of low density, high surface area skeleton materials to stabilize, catalyze, and control desorption product formation associated with such complex metal hydrides. A variety of framework chemistries and hydride / framework combinations were investigated to make a relatively broad assessment of the method's potential. In this project, the hydride / framework interactions were tuned to decrease desorption temperatures for highly stable compounds or increase desorption temperatures for unstable high capacity compounds, and to influence desorption product formation for improved reversibility. First principle modeling was used to explore heterogeneous catalysis of hydride reversibility by modeling H2 dissociation, hydrogen migration, and rehydrogenation. Atomic modeling also demonstrated enhanced NaTi(BH4)4 stabilization at nano-framework surfaces modified with multi-functional agents. Amine multi-functional agents were found to have more balanced interactions with nano-framework and hydride clusters than other functional groups investigated. Experimentation demonstrated that incorporation of Ca(BH4)2 and Mg(BH4)2 in aerogels enhanced hydride desorption kinetics. Carbon aerogels were identified as the most suitable nano-frameworks for hydride kinetic enhancement and high hydride loading. High loading of NaTi(BH4)4 ligand complex in SiO2 aerogel was achieved and hydride stability was improved with the aerogel. Although improvements of desorption kinetics was observed, the incorporation of

  19. Semi-catalyzed deuterium reactors for co-generation of 3He and synfuels (the CoSCD concept)

    International Nuclear Information System (INIS)

    The potential of developing semi-catalyzed deuterium reactors for co-generation of 3He and synthetic fuels is discussed. Such factors as environmental impact, siting, energy basics, and engineering technology are also discussed

  20. Selective conversion of polyenes to monoenes by RuCl(3) -catalyzed transfer hydrogenation: the case of cashew nutshell liquid.

    Science.gov (United States)

    Perdriau, Sébastien; Harder, Sjoerd; Heeres, Hero J; de Vries, Johannes G

    2012-12-01

    Cardanol, a constituent of cashew nutshell liquid (CNSL), was subjected to transfer hydrogenation catalyzed by RuCl(3) using isopropanol as a reductant. The side chain of cardanol, which is a mixture of a triene, a diene, and a monoene, was selectively reduced to the monoene. Surprisingly, it is the C8-C9 double bond that is retained with high selectivity. A similar transfer hydrogenation of linoleic acid derivatives succeeded only if the substrate contained an aromatic ring, such as a benzyl ester. TEM and a negative mercury test showed that the catalyst was homogeneous. By using ESI-MS, ruthenium complexes were identified that contained one, two, or even three molecules of substrate, most likely as allyl complexes. The interaction between ruthenium and the aromatic ring determines selectivity in the hydrogenation reaction. PMID:23060315

  1. Ultrafast and stable hydrogen generation from sodium borohydride in methanol and water over Fe-B nanoparticles

    Science.gov (United States)

    Ocon, Joey D.; Tuan, Trinh Ngoc; Yi, Youngmi; de Leon, Rizalinda L.; Lee, Jae Kwang; Lee, Jaeyoung

    2013-12-01

    Use of environmentally friendly hydrogen as fuel on a massive scale requires efficient storage and generation systems. Chemical hydrides, such as sodium borohydride (NaBH4), have the capacity to meet these needs as demonstrated by its high hydrogen storage efficiency. Here, we first report the catalytic activity of Fe-B nanoparticles supported on porous Ni foam - synthesized via a simple chemical reduction technique - for hydrogen generation from the mixtures of NaBH4, H2O, and CH3OH. Activation energies of the catalyzed hydrolysis (64.26 kJ mol-1) and methanolysis (7.02 kJ mol-1) are notably lower than other metal-boron catalysts previously reported. Methanol, in combination with a cheap but highly active Fe-B nanocatalysts, provides ultrafast rates of low temperature hydrogen generation from the sodium borohydride solutions.

  2. IDCOR approach to hydrogen generation, combustion, and burn control

    International Nuclear Information System (INIS)

    The IDCOR Program is developing the appropriate information and methodology to predict the following phenomena during severe accidents: 1) hydrogen generation, both in-vessel and ex-vessel, primarily from metal-water reactions; 2) hydrogen distribution in reactor containments; and 3) potential hazards of overpressurization or combustion of hydrogen. The information is being assembled into reports describing the phenomenology and incorporated into the IDCOR Modular Accident Analysis Program, in order to determine the behavior of hydrogen during accident sequences on four reference plants. From these analyses, conditions will be determined so that hydrogen burn control measures can be evaluated. A review is being made of various approaches for suppression of combustion or controlled burning to limit hydrogen to concentrations below the detonation range. The review considers the advantages and disadvantages of various hydrogen control systems concepts for reactor and containment combinations and, in addition, addresses the various concepts for eventual removal of hydrogen from containment

  3. Apparatus for hydrogen and carbon production via carbon aerosol-catalyzed dissociation of hydrocarbons

    Science.gov (United States)

    Muradov, Nazim Z. (Inventor); Smith, Franklyn (Inventor); Tabatabaie-Raissi, Ali (Inventor)

    2012-01-01

    A novel process and apparatus is disclosed for sustainable, continuous production of hydrogen and carbon by catalytic dissociation or decomposition of hydrocarbons at elevated temperatures using in-situ generated carbon particles. Carbon particles are produced by decomposition of carbonaceous materials in response to an energy input. The energy input can be provided by at least one of a non-oxidative and oxidative means. The non-oxidative means of the energy input includes a high temperature source, or different types of plasma, such as, thermal, non-thermal, microwave, corona discharge, glow discharge, dielectric barrier discharge, or radiation sources, such as, electron beam, gamma, ultraviolet (UV). The oxidative means of the energy input includes oxygen, air, ozone, nitrous oxide (NO.sub.2) and other oxidizing agents. The method, apparatus and process of the present invention is applicable to any gaseous or liquid hydrocarbon fuel and it produces no or significantly less CO.sub.2 emissions compared to conventional processes.

  4. On-site hydrogen generation from biodiesel and diesel

    OpenAIRE

    Martin, Stefan

    2015-01-01

    The lack of hydrogen infrastructure and distribution poses an obstacle for the introduction of fuel cell vehicles to the market. Therefore it is reasonable to consider using liquid fuels for on-board or on-site hydrogen generation. Within the FP7 project NEMESIS2+ (01/2012-06/2015, www.nemesis-project.eu) a small-scale hydrogen generator capable of producing 50 Nm3h-1 from biodiesel and diesel is currently being developed. Reduction of hydrogen production costs (< 5.0 € per kg), high overall...

  5. Hydrogen generation using silicon nanoparticles and their mixtures with alkali metal hydrides

    Science.gov (United States)

    Patki, Gauri Dilip

    Hydrogen is a promising energy carrier, for use in fuel cells, engines, and turbines for transportation or mobile applications. Hydrogen is desirable as an energy carrier, because its oxidation by air releases substantial energy (thermally or electrochemically) and produces only water as a product. In contrast, hydrocarbon energy carriers inevitably produce CO2, contributing to global warming. While CO2 capture may prove feasible in large stationary applications, implementing it in transportation and mobile applications is a daunting challenge. Thus a zero-emission energy carrier like hydrogen is especially needed in these cases. Use of H2 as an energy carrier also brings new challenges such as safe handling of compressed hydrogen and implementation of new transport, storage, and delivery processes and infrastructure. With current storage technologies, hydrogen's energy per volume is very low compared to other automobile fuels. High density storage of compressed hydrogen requires combinations of high pressure and/or low temperature that are not very practical. An alternative for storage is use of solid light weight hydrogenous material systems which have long durability, good adsorption properties and high activity. Substantial research has been conducted on carbon materials like activated carbon, carbon nanofibers, and carbon nanotubes due to their high theoretical hydrogen capacities. However, the theoretical values have not been achieved, and hydrogen uptake capacities in these materials are below 10 wt. %. In this thesis we investigated the use of silicon for hydrogen generation. Hydrogen generation via water oxidation of silicon had been ignored due to slow reaction kinetics. We hypothesized that the hydrogen generation rate could be improved by using high surface area silicon nanoparticles. Our laser-pyrolysis-produced nanoparticles showed surprisingly rapid hydrogen generation and high hydrogen yield, exceeding the theoretical maximum of two moles of H2 per

  6. Formic Acid Free Flowsheet Development To Eliminate Catalytic Hydrogen Generation In The Defense Waste Processing

    Energy Technology Data Exchange (ETDEWEB)

    Lambert, Dan P.; Stone, Michael E.; Newell, J. David; Fellinger, Terri L.; Bricker, Jonathan M.

    2012-09-14

    The Defense Waste Processing Facility (DWPF) processes legacy nuclear waste generated at the Savannah River Site (SRS) during production of plutonium and tritium demanded by the Cold War. The nuclear waste is first treated via a complex sequence of controlled chemical reactions and then vitrified into a borosilicate glass form and poured into stainless steel canisters. Converting the nuclear waste into borosilicate glass canisters is a safe, effective way to reduce the volume of the waste and stabilize the radionuclides. Testing was initiated to determine whether the elimination of formic acid from the DWPF's chemical processing flowsheet would eliminate catalytic hydrogen generation. Historically, hydrogen is generated in chemical processing of alkaline High Level Waste sludge in DWPF. In current processing, sludge is combined with nitric and formic acid to neutralize the waste, reduce mercury and manganese, destroy nitrite, and modify (thin) the slurry rheology. The noble metal catalyzed formic acid decomposition produces hydrogen and carbon dioxide. Elimination of formic acid by replacement with glycolic acid has the potential to eliminate the production of catalytic hydrogen. Flowsheet testing was performed to develop the nitric-glycolic acid flowsheet as an alternative to the nitric-formic flowsheet currently being processed at the DWPF. This new flowsheet has shown that mercury can be reduced and removed by steam stripping in DWPF with no catalytic hydrogen generation. All processing objectives were also met, including greatly reducing the Slurry Mix Evaporator (SME) product yield stress as compared to the baseline nitric/formic flowsheet. Ten DWPF tests were performed with nonradioactive simulants designed to cover a broad compositional range. No hydrogen was generated in testing without formic acid.

  7. A Study of Hydrogen Generation with Doubly-Fed Adjustable Speed Wind Generator

    Science.gov (United States)

    Kinoshita, Hirotaka; Takahashi, Rion; Murata, Toshiaki; Tamura, Junji; Sugimasa, Masatoshi; Komura, Akiyoshi; Futami, Motoo; Ichinose, Masaya; Ide, Kazumasa

    This paper presents a combination system of wind power generator and hydrogen generator. In the proposed system, Doubly-Fed Synchronous Generator (DFSG) is used as an adjustable speed wind generator, and an electrolyzer is connected to its terminal for hydrogen generation, which is controlled by power electronic converters. Output power from the wind generator is smoothed and supplied to the power system as well as to the electrolyzer to generate hydrogen under a cooperative control of the wind generator and the electrolyzer. The performance of the proposed system is investigated by simulation analyses, in which simulations are performed by using PSCAD/EMTDC.

  8. Hydrogenation of Olefins Catalyzed by Highly Active Titanocene/NaH or n-BuLi Catalyst Systems

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    The effects of the substituents on the cyclopentadienyl ring and the reducing agents on the catalytic activity and the stability of titanocene/NaH or n-BuLi systems for the hydrogenation of olefins were investigated. For the catalyst systems composed of titanocene/NaH or n-BuLi, the nature and the number of the substituents on the cyclopentadienyl ring control the catalytic behavior of those two systems. The effect of the reducing agent on the catalytic activity is relatively small. In addition, the characters of the hydrogenation of various olefins catalyzed respectively by Cp2TiCl2/NaH or n-BuLi systems were compared.

  9. Noble metal catalyzed aqueous phase hydrogenation and hydrodeoxygenation of lignin-derived pyrolysis oil and related model compounds.

    Science.gov (United States)

    Mu, Wei; Ben, Haoxi; Du, Xiaotang; Zhang, Xiaodan; Hu, Fan; Liu, Wei; Ragauskas, Arthur J; Deng, Yulin

    2014-12-01

    Aqueous phase hydrodeoxygenation of lignin pyrolysis oil and related model compounds were investigated using four noble metals supported on activated carbon. The hydrodeoxygenation of guaiacol has three major reaction pathways and the demethylation reaction, mainly catalyzed by Pd, Pt and Rh, produces catechol as the products. The presence of catechol and guaiacol in the reaction is responsible for the coke formation and the catalysts deactivation. As expected, there was a significant decrease in the specific surface area of Pd, Pt and Rh catalysts during the catalytic reaction because of the coke deposition. In contrast, no catechol was produced from guaiacol when Ru was used so a completely hydrogenation was accomplished. The lignin pyrolysis oil upgrading with Pt and Ru catalysts further validated the reaction mechanism deduced from model compounds. Fully hydrogenated bio-oil was produced with Ru catalyst. PMID:25280108

  10. Combustion characteristics of generating hydrogen during sodium-concrete reaction

    International Nuclear Information System (INIS)

    As a part of severe accident researches for sodium-cooled fast reactors (SFR), various experiments on sodium-concrete reaction (SCR) have been carried out in the several countries. Most of the experiments have been conducted under inert atmosphere conditions, and the data on concrete ablation, hydrogen generation rate, and aerosol release rate etc. have been obtained. On the other hand, the SCR under oxygen-existing conditions has become of major interest recently. In this case, as sodium-combustion heat plays an important role of the ignition energy, it is expected that hydrogen itself burns at the sodium pool surface. Since hydrogen, which is originally generated by the reaction of the sodium and water in the concrete, burns and returns to water again, this phenomenon is called 'hydrogen recombination'. In addition, the ratio that hydrogen is burnt (or consumed) at the sodium pool surface is called 'hydrogen recombination ratio'. We conducted an experiment in order to clarify the hydrogen recombination phenomenon in this study. In the experiment, sodium (about 25 grams) was heated up to about 500 degrees Celsius (deg-C). After that, mixed gas (nitrogen-oxygen) was injected in the atmosphere, and gaseous hydrogen was injected in the sodium pool to simulate the hydrogen evolution due to the SCR. While changing oxygen concentration in the atmosphere as an experimental parameter, relationship between the hydrogen recombination ratio and the oxygen concentration was investigated. As a result, it was found that the hydrogen recombination ratio increased with the increase of the oxygen concentration in the atmosphere. This means that when the oxygen exists in the room where the SCR occurs, hydrogen is consumed at the recombination ratio corresponding to the oxygen concentration. That is, it can be expected that build-up of hydrogen is reduced by this hydrogen recombination. (author)

  11. Hydrogen-based power generation from bioethanol steam reforming

    Energy Technology Data Exchange (ETDEWEB)

    Tasnadi-Asztalos, Zs., E-mail: tazsolt@chem.ubbcluj.ro; Cormos, C. C., E-mail: cormos@chem.ubbcluj.ro; Agachi, P. S. [Babes-Bolyai University, Faculty of Chemistry and Chemical Engineering, 11 Arany Janos, Postal code: 400028, Cluj-Napoca (Romania)

    2015-12-23

    This paper is evaluating two power generation concepts based on hydrogen produced from bioethanol steam reforming at industrial scale without and with carbon capture. The power generation from bioethanol conversion is based on two important steps: hydrogen production from bioethanol catalytic steam reforming and electricity generation using a hydrogen-fuelled gas turbine. As carbon capture method to be assessed in hydrogen-based power generation from bioethanol steam reforming, the gas-liquid absorption using methyl-di-ethanol-amine (MDEA) was used. Bioethanol is a renewable energy carrier mainly produced from biomass fermentation. Steam reforming of bioethanol (SRE) provides a promising method for hydrogen and power production from renewable resources. SRE is performed at high temperatures (e.g. 800-900°C) to reduce the reforming by-products (e.g. ethane, ethene). The power generation from hydrogen was done with M701G2 gas turbine (334 MW net power output). Hydrogen was obtained through catalytic steam reforming of bioethanol without and with carbon capture. For the evaluated plant concepts the following key performance indicators were assessed: fuel consumption, gross and net power outputs, net electrical efficiency, ancillary consumptions, carbon capture rate, specific CO{sub 2} emission etc. As the results show, the power generation based on bioethanol conversion has high energy efficiency and low carbon footprint.

  12. Hydrogen-based power generation from bioethanol steam reforming

    Science.gov (United States)

    Tasnadi-Asztalos, Zs.; Cormos, C. C.; Agachi, P. S.

    2015-12-01

    This paper is evaluating two power generation concepts based on hydrogen produced from bioethanol steam reforming at industrial scale without and with carbon capture. The power generation from bioethanol conversion is based on two important steps: hydrogen production from bioethanol catalytic steam reforming and electricity generation using a hydrogen-fuelled gas turbine. As carbon capture method to be assessed in hydrogen-based power generation from bioethanol steam reforming, the gas-liquid absorption using methyl-di-ethanol-amine (MDEA) was used. Bioethanol is a renewable energy carrier mainly produced from biomass fermentation. Steam reforming of bioethanol (SRE) provides a promising method for hydrogen and power production from renewable resources. SRE is performed at high temperatures (e.g. 800-900°C) to reduce the reforming by-products (e.g. ethane, ethene). The power generation from hydrogen was done with M701G2 gas turbine (334 MW net power output). Hydrogen was obtained through catalytic steam reforming of bioethanol without and with carbon capture. For the evaluated plant concepts the following key performance indicators were assessed: fuel consumption, gross and net power outputs, net electrical efficiency, ancillary consumptions, carbon capture rate, specific CO2 emission etc. As the results show, the power generation based on bioethanol conversion has high energy efficiency and low carbon footprint.

  13. Hydrogen-based power generation from bioethanol steam reforming

    International Nuclear Information System (INIS)

    This paper is evaluating two power generation concepts based on hydrogen produced from bioethanol steam reforming at industrial scale without and with carbon capture. The power generation from bioethanol conversion is based on two important steps: hydrogen production from bioethanol catalytic steam reforming and electricity generation using a hydrogen-fuelled gas turbine. As carbon capture method to be assessed in hydrogen-based power generation from bioethanol steam reforming, the gas-liquid absorption using methyl-di-ethanol-amine (MDEA) was used. Bioethanol is a renewable energy carrier mainly produced from biomass fermentation. Steam reforming of bioethanol (SRE) provides a promising method for hydrogen and power production from renewable resources. SRE is performed at high temperatures (e.g. 800-900°C) to reduce the reforming by-products (e.g. ethane, ethene). The power generation from hydrogen was done with M701G2 gas turbine (334 MW net power output). Hydrogen was obtained through catalytic steam reforming of bioethanol without and with carbon capture. For the evaluated plant concepts the following key performance indicators were assessed: fuel consumption, gross and net power outputs, net electrical efficiency, ancillary consumptions, carbon capture rate, specific CO2 emission etc. As the results show, the power generation based on bioethanol conversion has high energy efficiency and low carbon footprint

  14. Study on Kinetics of Hydrogen Absorption by Metal Hydride Slurries Ⅱ. Hydrogenation of Benzene Catalyzed by MlNi5

    Institute of Scientific and Technical Information of China (English)

    安越; 陈长聘; 徐国华; 蔡官明; 王启东

    2002-01-01

    The feasibility of the hydrogenation of benzene into cyclohexane over the hydrogen storage alloy MlNi5 catalyst was studied in the temperature range of 402~463 K. The results show that the reaction order is zero and the energy of activation is 28.9 kJmol-1.

  15. On-site production of electrolytic hydrogen for generator cooling

    Science.gov (United States)

    Mehta, B. R.

    Hydrogen produced by water electrolysis could be cost effective over the merchant hydrogen used for generator cooling. Advanced water electrolyzers are being developed specifically for this utility application. These designs are based on solid-polymer-electrolyte and alkaline water electrolysis technologies. This paper describes the status of electrolyzer development and demonstration projects.

  16. Efficient Electrochemical Hydrogen Peroxide Generation in Water Project

    Data.gov (United States)

    National Aeronautics and Space Administration — An electrochemical cell is proposed for the efficient generation of 3% hydrogen peroxide (H2O2) in pure water using only power, oxygen and water. H2O2 is an...

  17. Effective hydrogen generator testing for on-site small engine

    Science.gov (United States)

    Chaiwongsa, Praitoon; Pornsuwancharoen, Nithiroth; Yupapin, Preecha P.

    2009-07-01

    We propose a new concept of hydrogen generator testing for on-site small engine. In general, there is a trade-off between simpler vehicle design and infrastructure issues, for instance, liquid fuels such as gasoline and methanol for small engine use. In this article we compare the hydrogen gases combination the gasoline between normal systems (gasoline only) for small engine. The advantage of the hydrogen combines gasoline for small engine saving the gasoline 25%. Furthermore, the new concept of hydrogen combination for diesel engine, bio-diesel engine, liquid petroleum gas (LPG), natural gas vehicle (NGV), which is discussed in details.

  18. Cold weather hydrogen generation system and method of operation

    Science.gov (United States)

    Dreier, Ken Wayne; Kowalski, Michael Thomas; Porter, Stephen Charles; Chow, Oscar Ken; Borland, Nicholas Paul; Goyette, Stephen Arthur

    2010-12-14

    A system for providing hydrogen gas is provided. The system includes a hydrogen generator that produces gas from water. One or more heat generation devices are arranged to provide heating of the enclosure during different modes of operation to prevent freezing of components. A plurality of temperature sensors are arranged and coupled to a controller to selectively activate a heat source if the temperature of the component is less than a predetermined temperature.

  19. Enantioselective Hydrogenation of Aromatic Ketones Catalyzed by Ru Complex Using a New Bipyridyl Diphosphine

    Institute of Scientific and Technical Information of China (English)

    CHEN Li; FU Xing-Li; MING Fang-Yong; CHEN Hua; LI Xian-Jun

    2008-01-01

    A series of RuCl2(bipyridyldiphosphine)(1,2-diamine)complexes were synthesized and applied to the asymmetric hydrogenation of aromatic ketones.Solvent effect and a wide variety of aromatic ketones were explored and up to 96% enantioselectivity was achieved in the hydrogenation of o-bromoacetophenone.

  20. Alkali free hydrolysis of sodium borohydride for hydrogen generation under pressure

    Energy Technology Data Exchange (ETDEWEB)

    Ferreira, M.J.F.; Pinto, A.M.F.R. [Centro de Estudos de Fenomenos de Transporte, Departamento de Engenharia Quimica, Faculdade de Engenharia da Universidade do Porto, Rua Dr. Roberto Frias s/n, 4200-465 Porto (Portugal); Gales, L. [Instituto de Biologia Molecular e Celular, Universidade do Porto, Rua do Campo Alegre 823, 4150-180 Porto and Instituto de Ciencias Biomedicas Abel Salazar, Largo Prof. Abel Salazar 2, 4099-003 Porto (Portugal); Fernandes, V.R.; Rangel, C.M. [Laboratorio Nacional de Energia e Geologia - LNEG, Fuel Cells and Hydrogen Unit Estrada do Paco do Lumiar 22, 1649-038 Lisboa (Portugal)

    2010-09-15

    The present study is related with the production of hydrogen gas (H{sub 2}), at elevated pressures and with high gravimetric storage density, to supply a PEM fuel cell on-demand. To achieve this goal, solid sodium borohydride (NaBH{sub 4}) was mixed with a proper amount of a powder reused nickel-ruthenium based catalyst (Ni-Ru based/NaBH{sub 4}: 0.2 and 0.4 g/g; {approx}150 times reused) inside the bottom of a batch reactor. Then, a stoichiometric amount of pure liquid water (H{sub 2}O/NaBH{sub 4}: 2-8 mol/mol) was added and the catalyzed NaBH{sub 4} hydrolysis evolved, in the absence of an alkali inhibitor. In this way, this research work is designated alkali free hydrolysis of NaBH{sub 4} for H{sub 2} generation. This type of hydrolysis is excellent from an environmental point of view because it does not involve strongly caustic solutions. Experiments were performed in three batch reactors with internal volumes 646, 369 and 229 cm{sup 3}, and having different bottom geometries (flat and conical shapes). The H{sub 2} generated was a function of the added water and completion was achieved with H{sub 2}O/NaBH{sub 4} = 8 mol/mol. The results show that hydrogen yields and rates increase remarkably increasing both system temperature and pressure. Reactor bottom shape influences deeply H{sub 2} generation: the conical bottom shape greatly enhances the rate and practically eliminates the reaction induction time. Our system of compressed hydrogen generation up to 1.26 MPa shows 6.3 wt% and 70 kg m{sup -3}, respectively, for gravimetric and volumetric hydrogen storage capacities (materials-only basis) and therefore is a viable hydrogen storage candidate for portable applications. (author)

  1. Ruthenium-Catalyzed Transfer Hydrogenation for C-C Bond Formation: Hydrohydroxyalkylation and Hydroaminoalkylation via Reactant Redox Pairs.

    Science.gov (United States)

    Perez, Felix; Oda, Susumu; Geary, Laina M; Krische, Michael J

    2016-06-01

    Merging the chemistry of transfer hydrogenation and carbonyl or imine addition, a broad new family of redox-neutral or reductive hydrohydroxyalkylations and hydroaminomethylations have been developed. In these processes, hydrogen redistribution between alcohols and π-unsaturated reactants is accompanied by C-C bond formation, enabling direct conversion of lower alcohols to higher alcohols. Similarly, hydrogen redistribution between amines to π-unsaturated reactants results in direct conversion of lower amines to higher amines. Alternatively, equivalent products of hydrohydroxyalkylation and hydroaminomethylation may be generated through the reaction of carbonyl compounds or imines with π-unsaturated reactants under the conditions of 2-propanol-mediated reductive coupling. Finally, using vicinally dioxygenated reactants, that is, diol, ketols, or diones, successive transfer hydrogenative coupling occurs to generate 2 C-C bonds, resulting in products of formal [4+2] cycloaddition. PMID:27573275

  2. Hydrogen desorption properties of magnesium hydride catalyzed multiply with carbon and silicon

    Energy Technology Data Exchange (ETDEWEB)

    Klimkowicz, Alicja [AGH University of Science and Technology Faculty of Energy and Fuels, al. A. Mickiewicza 30, 30-059 Krakow (Poland); Shibaura Institute of Technology, Department of Engineering Science and Mechanics, 3-7-5 Toyosu, Koto-ku 135-8548, Tokyo (Japan); Takasaki, Akito, E-mail: takasaki@sic.shibaura-it.ac.jp [Shibaura Institute of Technology, Department of Engineering Science and Mechanics, 3-7-5 Toyosu, Koto-ku 135-8548, Tokyo (Japan); Gondek, Łukasz; Figiel, Henryk [AGH University of Science and Technology, Faculty of Physics and Applied Computer Science, al. A. Mickiewicza 30, 30-059 Krakow (Poland); Świerczek, Konrad [AGH University of Science and Technology Faculty of Energy and Fuels, al. A. Mickiewicza 30, 30-059 Krakow (Poland)

    2015-10-05

    Highlights: • Crystal structure of 2 mol MgH{sub 2} + (1 − X) mol C + X mol Si (for X = 0, 0.25, 0.5, 0.75 and 1). • Enhanced hydrogen desorption properties. • Lowered temperature of hydrogen desorption for MgH{sub 2} with the multiple addition of C and Si. • Distribution of Si and C on MgH{sub 2} particles after mechanical milling. - Abstract: Magnesium hydride (MgH{sub 2}) is considered as one of hydrogen storage materials. However, the application is limited because of slow hydrogen kinetics and high thermodynamic stability. In this study, MgH{sub 2} powders were mechanically milled with graphite (C) and/or silicon (Si) powders, and effect of multiple addition of C and Si on hydrogen desorption properties was investigated. The multiple addition caused a decrease of the hydrogen desorption (onset and peak) temperatures more than single addition, and the lowest activation energy for hydrogen desorption, 62 kJ/mol, was obtained from sample powders of (2 mol MgH{sub 2} + 0.5 mol C + 0.5 mol Si). The surface of the sample powders after mechanical milling revealed a good distribution of C on the MgH{sub 2} surface and a presence of finer Si particles.

  3. Hydrogen desorption properties of magnesium hydride catalyzed multiply with carbon and silicon

    International Nuclear Information System (INIS)

    Highlights: • Crystal structure of 2 mol MgH2 + (1 − X) mol C + X mol Si (for X = 0, 0.25, 0.5, 0.75 and 1). • Enhanced hydrogen desorption properties. • Lowered temperature of hydrogen desorption for MgH2 with the multiple addition of C and Si. • Distribution of Si and C on MgH2 particles after mechanical milling. - Abstract: Magnesium hydride (MgH2) is considered as one of hydrogen storage materials. However, the application is limited because of slow hydrogen kinetics and high thermodynamic stability. In this study, MgH2 powders were mechanically milled with graphite (C) and/or silicon (Si) powders, and effect of multiple addition of C and Si on hydrogen desorption properties was investigated. The multiple addition caused a decrease of the hydrogen desorption (onset and peak) temperatures more than single addition, and the lowest activation energy for hydrogen desorption, 62 kJ/mol, was obtained from sample powders of (2 mol MgH2 + 0.5 mol C + 0.5 mol Si). The surface of the sample powders after mechanical milling revealed a good distribution of C on the MgH2 surface and a presence of finer Si particles

  4. Generation and migration of hydrogen in nuclear waste repositories

    International Nuclear Information System (INIS)

    Document available in extended abstract form only. There is concern that hydrogen generated by anaerobic corrosion of metals in a repository could affect adversely the functional properties of radioactive waste repository barriers if the pressure caused by hydrogen accumulation was allowed to increase beyond some limits. This problem can be solved either by preventing fast generation of hydrogen from metals involved in a repository or by using barriers permeable enough not to allow accumulation of hydrogen to achieve pressure leading possibly to failure of barriers. This concern is particularly relevant for repository concepts with steel based canisters, which is the case of the Czech DGR concept. This article describes the work conducted in Nuclear Research Institute Rez (NRI) focused both on determining hydrogen generation under various conditions, measuring pressure arisen due to accumulation of hydrogen before a compacted, saturated bentonite layer and measuring transport of hydrogen through it. Hydrogen generation or carbon steel corrosion rates were determined both in solution simulated bentonite pore water in anaerobic glove box with content of residual oxygen less than 0.1 ppm under various temperatures and in contact of metal with compacted bentonite in special corrosion apparatus under conditions simulated conditions in a deep geological repository. The apparatus developed in NRI contained carbon steel disc in direct contact with compacted bentonite, which was saturated from above by synthetic granitic water under high pressure. A membrane below carbon steel samples enabled to measure pressure between carbon steel and bentonite. The increase of pressure indicates hydrogen accumulation due to corrosion. Also the total pressure caused by combination of swelling pressure, water pressure and hydrogen pressure was measured. Corrosion rates were determined from weigh loss of carbon steel samples. Two types of devices were used for measuring hydrogen migration

  5. Ruthenium-Catalyzed Selective Hydrogenation of bis-Arylidene Tetramic Acids. Application to the Synthesis of Novel Structurally Diverse Pyrrolidine-2,4-diones

    Directory of Open Access Journals (Sweden)

    Olga Igglessi-Markopoulou

    2011-07-01

    Full Text Available Catalytic hydrogenation of 3,5-bis-arylidenetetramic acids, known for their biological activity, has been developed. The chemoselective ruthenium-catalyzed reduction of the exocyclic carbon-carbon double bonds on pyrrolidine-2,4-dione ring system, containing other reducible functions, has been investigated. Depending on the substrate the yield of the hydrogenation process can reach up to 95%. The structural elucidation has been established using NMR and HRMS spectral data.

  6. Short term hydrogen generation following LOCA and loss of ECCS

    International Nuclear Information System (INIS)

    The purpose of the present study is to estimate the amount of hydrogen that can be generated due to metal water reaction following LOCA and loss of ECCS in a 500 MWe PHWR. A computer code HYGEN (Hydrogen Generation) written in FORTRAN calculates time-dependent fuel temperature during the post blowdown period and the amount of hydrogen generated as a result of metal water reaction. It is seen from the analyses that metal water reaction depends on fuel bundle power, its initial temperature and steam flow conditions. At present, four groups of channels have been analysed for different steam flow conditions, and it is found that, for an about 5 gm/sec steam flow condition, the maximum of amount of hydrogen is generated (5.76 x 104 gm-mole) due to the zircaloy - steam reaction. This amount of hydrogen, when considered mixed in volume V1 (drywell) of the reactor building, means that the global concentration reaches about 2.76% by volume. So, it is seen that in the short term, the global hydrogen concentration in the reactor building is well below the flammability limit of 4% by volume. (author) 4 refs., 1 tab., 10 figs

  7. Biomimetic oxidation of carbamazepine with hydrogen peroxide catalyzed by a manganese porphyrin

    Directory of Open Access Journals (Sweden)

    Cláudia M. B. Neves

    2012-01-01

    Full Text Available This laboratory project is planned for an undergraduate chemistry laboratory in which students prepare a manganese porphyrin able to mimic the oxidative metabolism of carbamazepine, one of the most frequently prescribed drugs in the treatment of epilepsy. The in vitro oxidation of carbamazepine results in the formation of the corresponding 10,11-epoxide, the main in vivo metabolite. The reaction is catalyzed by manganese porphyrin in the presence of H2O2, an environmentally-friendly oxidant. Through this project students will develop their skills in organic synthesis, coordination chemistry, chromatographic techniques such as TLC and HPLC, UV-visible spectrophotometry, and NMR spectroscopy.

  8. Biomimetic oxidation of carbamazepine with hydrogen peroxide catalyzed by a manganese porphyrin

    Energy Technology Data Exchange (ETDEWEB)

    Neves, Claudia M.B.; Simoes, Mario M.Q.; Domingues, Fernando M.J.; Neves, M. Graca P.M.S.; Cavaleiro, Jose A.S., E-mail: msimoes@ua.pt [Dept. de Quimica, QOPNA, Universidade de Aveiro (Portugal)

    2012-07-01

    This laboratory project is planned for an undergraduate chemistry laboratory in which students prepare a manganese porphyrin able to mimic the oxidative metabolism of carbamazepine, one of the most frequently prescribed drugs in the treatment of epilepsy. The in vitro oxidation of carbamazepine results in the formation of the corresponding 10,11-epoxide, the main in vivo metabolite. The reaction is catalyzed by manganese porphyrin in the presence of H{sub 2}O{sub 2}, an environmentally-friendly oxidant. Through this project students will develop their skills in organic synthesis, coordination chemistry, chromatographic techniques such as TLC and HPLC, UV-visible spectrophotometry, and NMR spectroscopy. (author)

  9. Biomimetic oxidation of carbamazepine with hydrogen peroxide catalyzed by a manganese porphyrin

    International Nuclear Information System (INIS)

    This laboratory project is planned for an undergraduate chemistry laboratory in which students prepare a manganese porphyrin able to mimic the oxidative metabolism of carbamazepine, one of the most frequently prescribed drugs in the treatment of epilepsy. The in vitro oxidation of carbamazepine results in the formation of the corresponding 10,11-epoxide, the main in vivo metabolite. The reaction is catalyzed by manganese porphyrin in the presence of H2O2, an environmentally-friendly oxidant. Through this project students will develop their skills in organic synthesis, coordination chemistry, chromatographic techniques such as TLC and HPLC, UV-visible spectrophotometry, and NMR spectroscopy. (author)

  10. Chloride ion-catalyzed generation of difluorocarbene for efficient preparation of gem-difluorinated cyclopropenes and cyclopropanes

    KAUST Repository

    Wang, Fei

    2011-01-01

    A chloride ion-catalyzed generation of difluorocarbene from a relatively non-toxic and inexpensive precursor, Me3SiCF2Cl (1), under mild and neutral conditions leads to an efficient preparation of gem-difluorocyclopropenes and difluorocyclopropanes through [2 + 1] cycloaddition reactions with alkynes and alkenes, respectively. © 2011 The Royal Society of Chemistry.

  11. Hydrogen Production from the Next Generation Nuclear Plant

    International Nuclear Information System (INIS)

    The Next Generation Nuclear Plant (NGNP) is a high temperature gas-cooled reactor that will be capable of producing hydrogen, electricity and/or high temperature process heat for industrial use. The project has initiated the conceptual design phase and when completed will demonstrate the viability of hydrogen generation using nuclear produced process heat. This paper explains how industry and the U.S. Government are cooperating to advance nuclear hydrogen technology. It also describes the issues being explored and the results of recent R and D including materials development and testing, thermal-fluids research, and systems analysis. The paper also describes the hydrogen production technologies being considered (including various thermochemical processes and high-temperature electrolysis)

  12. Hydrogenation of esters catalyzed by ruthenium PN3-Pincer complexes containing an aminophosphine arm

    KAUST Repository

    Chen, Tao

    2014-08-11

    Hydrogenation of esters under mild conditions was achieved using air-stable ruthenium PN3-pincer complexes containing an aminophosphine arm. High efficiency was achieved even in the presence of water. DFT studies suggest a bimolecular proton shuttle mechanism which allows H2 to be activated by the relatively stable catalyst with a reasonably low transition state barrier. © 2014 American Chemical Society.

  13. Degradation of polycyclic aromatic hydrocarbons by hydrogen peroxide catalyzed by heterogeneous polymeric metal chelates

    Czech Academy of Sciences Publication Activity Database

    Baldrian, Petr; Cajthaml, Tomáš; Merhautová, Věra; Gabriel, Jiří; Nerud, František; Stopka, P.; Hrubý, Martin; Beneš, Milan J.

    2005-01-01

    Roč. 59, - (2005), s. 267-274. ISSN 0926-3373 R&D Projects: GA AV ČR IBS5020306; GA ČR GA203/01/0944 Institutional research plan: CEZ:AV0Z7090911 Keywords : degradation * polycyclic aromatic hydrocarbon * hydrogen peroxide Subject RIV: EE - Microbiology, Virology Impact factor: 3.809, year: 2005

  14. RANEY® Ni catalyzed transfer hydrogenation of levulinate esters to γ-valerolactone at room temperature.

    Science.gov (United States)

    Yang, Zhen; Huang, Yao-Bing; Guo, Qing-Xiang; Fu, Yao

    2013-06-11

    A catalytic transfer hydrogenation process was developed for the production of γ-valerolactone (GVL) from ethyl levulinate (EL) and a H-donor at room temperature. Ethyl levulinate was almost quantitatively converted to γ-valerolactone. Further, a two step process for producing GVL from biomass derived platform molecules was also reported. PMID:23648801

  15. Molecular cobalt pentapyridine catalysts for generating hydrogen from water

    Science.gov (United States)

    Long, Jeffrey R; Chang, Christopher J; Sun, Yujie

    2013-11-05

    A composition of matter suitable for the generation of hydrogen from water is described, the positively charged cation of the composition including the moiety of the general formula. [(PY5Me.sub.2)CoL].sup.2+, where L can be H.sub.2O, OH.sup.-, a halide, alcohol, ether, amine, and the like. In embodiments of the invention, water, such as tap water or sea water can be subject to low electric potentials, with the result being, among other things, the generation of hydrogen.

  16. Generation of correlated photons in hydrogenated amorphous-silicon waveguides

    OpenAIRE

    Clemmen, S.; Perret, A; Selvaraja, Shankar Kumar; Bogaerts, Wim; Van Thourhout, Dries; Baets, Roel; Emplit, Ph.; Massar, S.

    2011-01-01

    We report the first (to our knowledge) observation of correlated photon emission in hydrogenated amorphous- silicon waveguides. We compare this to photon generation in crystalline silicon waveguides with the same geome- try. In particular, we show that amorphous silicon has a higher nonlinearity and competes with crystalline silicon in spite of higher loss.

  17. Asymmetric transfer hydrogenation of ketones catalyzed by nickel complex with new PNO-type ligands

    Institute of Scientific and Technical Information of China (English)

    Zhen Rong Dong; Yan Yun Li; Shen Luan Yu; Guo Song Sun; Jing Xing Gao

    2012-01-01

    The new polydentate mixed-N,P,O chiral ligands have been synthesized by the condensation of bis(o-formylphenyl)-phenylphosphane and R-phenylglycinol in CHCl3,and fully characterized by IR,NMR and EIMS spectra.These ligands were employed with a simple Ni complex Ni(PPh8)2Cl2 in situ as catalytic systems for asymmetric transfer hydrogenation of ketones,and the corresponding optical alcohols were obtained with up to 84% ee under mild conditions.

  18. Transfer hydrogenation reactions catalyzed by chiral half-sandwich Ruthenium complexes derived from Proline

    Indian Academy of Sciences (India)

    ARUN KUMAR PANDIA KUMAR; ASHOKA G SAMUELSON

    2016-09-01

    Chiral ruthenium half-sandwich complexes were prepared using a chelating diamine made from proline with a phenyl, ethyl, or benzyl group, instead of hydrogen on one of the coordinating arms. Three of these complexes were obtained as single diastereoisomers and their configuration identified by X-ray crystallography. The complexes are recyclable catalysts for the reduction of ketones to chiral alcohols in water. A ruthenium hydride species is identified as the active species by NMR spectroscopy and isotopic labelling experiments.Maximum enantio-selectivity was attained when a phenyl group was directly attached to the primary amine on the diamine ligand derived from proline.

  19. Visible light-driven hydrogen evolution from water catalyzed by a molecular cobalt complex.

    Science.gov (United States)

    Tong, Lianpeng; Zong, Ruifa; Thummel, Randolph P

    2014-04-01

    An approximately planar tetradentate polypyridine ligand, 8-(1″,10″-phenanthrol-2″-yl)-2-(pyrid-2'-yl)quinoline (ppq), has been prepared by two sequential Friedländer condensations. The ligand readily accommodates Co(II) bearing two axial chlorides, and the resulting complex is reasonably soluble in water. In DMF the complex shows three well-behaved redox waves in the window of 0 to -1.4 V (vs SHE). However in pH 7 buffer the third wave is obscured by a catalytic current at -0.95 V, indicating hydrogen production that appears to involve a proton-coupled electron-transfer event. The complex [Co(ppq)Cl2] (6) in pH 4 aqueous solution, together with [Ru(bpy)3]Cl2 and ascorbic acid as a sacrificial electron donor, in the presence of blue light (λmax = 469 nm) produces hydrogen with an initial TOF = 586 h(-1). PMID:24635104

  20. A planar microfabricated electrolyzer for hydrogen and oxygen generation

    Energy Technology Data Exchange (ETDEWEB)

    Jiang, L.; Myer, B.; Pau, S. [University of Arizona, College of Optical Sciences, 1630 E. University Blvd., Tucson, AZ 85721 (United States); Tellefsen, K. [Cookson Electronics Inc., 109 Corporate Blvd., South Plainfield, NJ 07080 (United States)

    2009-03-01

    We present the design, fabrication and testing of a microfabricated planar reactor for the hydrogen evolution reaction (HER) using thin film Pt electrodes and polydimethylsiloxane (PDMS) fluidic chamber. The reactor is designed to separate gases by flow dynamics and reactor flow is analyzed by three-dimensional finite element analysis. The planar geometry is scalable, compact and stackable. Using KOH 28 wt% electrolyte, we have achieved a hydrogen generation density of 0.23 kg h{sup -1} m{sup -3} and an efficiency of 48% with a flow rate of 10 ml min{sup -1} and cell voltage of 3 V. (author)

  1. Hydrogen Peroxide Gas Generator Cycle with a Reciprocating Pump

    Energy Technology Data Exchange (ETDEWEB)

    Whitehead, J C

    2002-06-11

    A four-chamber piston pump is powered by decomposed 85% hydrogen peroxide. The performance envelope of the evolving 400 gram pump has been expanded to 172 cc/s water flow at discharge pressures near 5 MPa. A gas generator cycle system using the pump has been tested under similar conditions of pressure and flow. The powerhead gas is derived from a small fraction of the pumped hydrogen peroxide, and the system starts from tank pressures as low as 0.2 MPa. The effects of steam condensation on performance have been evaluated.

  2. Perspectives for generation companies and the emerging hydrogen economy

    International Nuclear Information System (INIS)

    'Full text:' Canadian and global power generation supply is evolving towards inclusion of emerging types of technologies for electricity production. Although much of Canadian electricity supply will continue to be derived from traditional sources in the foreseeable future the band for capital cost competitiveness is narrowing between the once clear-cut technological winners and emerging generation technologies creating opportunity for new technologies to commercialize in the market. OPG has been active in the development and commercialization of stationary high temperature fuel cells for several years. The major activity has been a partnering initiative to engineer and implement Solid Oxide Fuel Cell (SOFC) demonstration installations. The relationship with SOFC developer Siemens-Westinghouse out of Pittsburgh has allowed OPG to maintain an ongoing involvement in the emerging fuel cell industry, while exploring the broader implications of this technology for the power industry business model. OPG is part of the 'Hydrogen Village Partnership'. The Hydrogen Village will demonstrate and deploy various hydrogen production, storage and delivery techniques as well as applications of hydrogen such as fuel cells for stationary, transportation (mobile) and portable applications. OPG maintains an active role in the demonstration of emerging technologies for a number of reasons: 1) advancing commercialization of emerging generation technologies, 2) 'hands-on' participation in the deployment of such technology in order to gather and apply market knowledge 3) Involvement in developing technology as a part of commitment to sustainable development. (author)

  3. Wind energy-hydrogen storage hybrid power generation

    Energy Technology Data Exchange (ETDEWEB)

    Wenjei Yang; Orhan Aydin [University of Michigan, Ann Arbor, MI (United States). Dept. of Mechanical Engineering and Applied Mechanics

    2001-07-01

    In this theoretical investigation, a hybrid power generation system utilizing wind energy and hydrogen storage is presented. Firstly, the available wind energy is determined, which is followed by evaluating the efficiency of the wind energy conversion system. A revised model of windmill is proposed from which wind power density and electric power output are determined. When the load demand is less than the output of the generation, the excess electric power is relayed to the electrolytic cell where it is used to electrolyse the de-ionized water. Hydrogen thus produced can be stored as hydrogen compressed gas or liquid. Once the hydrogen is stored in an appropriate high-pressure vessel, it can be used in a combustion engine, fuel cell, or burned in a water-cooled burner to produce a very high-quality steam for space heating, or to drive a turbine to generate electric power. It can also be combined with organic materials to produce synthetic fuels. The conclusion is that the system produces no harmful waste and depletes no resources. Note that this system also works well with a solar collector instead of a windmill. (author)

  4. Unique Reactivity Patterns Catalyzed by Internal Lewis Acid Assisted Hydrogen Bond Donors

    Science.gov (United States)

    Auvil, Tyler Jay

    The advancement of hydrogen bond donor (HBD) organocatalysis has been inhibited by a number of challenges. Conventional HBDs suffer from high catalyst loadings and operate in only limited types of reactions, typically the activation of 1,2- and 1,4-acceptors for nucleophilic attack. One strategy to address the shortcomings of HBD catalysis is to design innovative catalysts with improved reactivity. To this end, boronate ureas have been developed as a new family of enhanced HBD catalysts that enable useful new reactivity patterns. Boronate ureas are easily-accessible, small organic molecules that benefit from improved catalytic abilities plausibly due to internal coordination of the urea carbonyl to a strategically placed Lewis acid. Optimization of the boronate urea scaffold has revealed their enhanced catalytic activity, enabling new directions in HBD catalysis. The discovery of boronate ureas has allowed for the unveiling of new HBD activation modes, providing unique reactivity patterns that are inaccessible with conventional HBD catalysts. Among these reactivity patterns is the activation of strained nitrocyclopropane carboxylates for nucleophilic ring-opening reactions, which affords a swift route to access gamma-amino-alpha-nitroester building blocks. The ring-opening method was highlighted by its utilization in the total synthesis of a CB-1 receptor inverse agonist, which was recently patented by Eli Lilly. Additionally, boronate ureas can elicit carbene-like reactivity from alpha-diazocarbonyl compounds, allowing for organocatalytic heteroatom-hydrogen insertions reactions, the first of their kind. The boronate urea activation of alpha-nitrodiazoesters has permitted the development of an unsymmetric double alpha-arylation process, affording a synthetically challenging motif in a single flask. The alpha-arylation reaction proceeds through a conceptually novel organocatalytic transient N--H insertion process, employing anilines as carbene activators. The use

  5. Another role for CO with nitrogenase? CO stimulates hydrogen evolution catalyzed by variant Azotobacter vinelandii Mo-nitrogenases.

    Science.gov (United States)

    Fisher, Karl; Hare, Nathan D; Newton, William E

    2014-10-01

    A likely entry/exit path for nitrogenase substrates, products, and/or protons involves residues α277(Arg), α192(Ser), and α356(Gly), all of which are highly conserved among MoFe proteins from different organisms. The α192(Ser) and α277(Arg) residues form part of a hydrogen-bonded network that also involves α195(His), which interacts with a FeMo cofactor-based sulfide. The terminal amino groups of α277(Arg) are also hydrogen-bonded directly to α281(Tyr), which resides at the surface of the MoFe protein. Individual amino acid substitutions placed at position α277 or α192 resulted in a variety of effects on the catalytic and/or spectroscopic properties of the resulting variant MoFe protein. Of particular interest was the effect of CO on H2 evolution catalyzed by three MoFe protein variants, α277(Cys), α192(Asp), and α192(Glu). All three variants exhibited CO stimulation of H2 evolution under high-electron flux conditions but not under low-electron flux conditions. This observation is best explained by these variants being redox-compromised but only at the most reduced redox states of the MoFe protein. Normally, these states are accessed and operational only under high-electron flux conditions, and the effect of added CO is to prevent access to these most reduced redox states, resulting in a normal rate of catalysis. Furthermore, via correlation of the effect of pH changes on H2 evolution activity for both the wild type and the α277(Cys) MoFe protein variant under argon, with or without 10% CO present, likely pathways for the delivery of a proton to the FeMo cofactor were identified. PMID:25203280

  6. Silver-catalyzed silicon-hydrogen bond functionalization by carbene insertion.

    Science.gov (United States)

    Iglesias, M José; Nicasio, M Carmen; Caballero, Ana; Pérez, Pedro J

    2013-01-28

    The catalytic functionalization of silicon-hydrogen bonds by means of the insertion of carbene units :CHCO(2)Et from ethyl diazoacetate (EDA) has been achieved using a silver-based catalyst, constituting the first example of this metal to promote this transformation. Competition experiments have revealed that the relative reactivity of substituted silanes depends on the bond dissociation energy of the Si-H bond (tertiary > secondary > primary for ethyl substituted). In the presence of bulky substituents such order reverts to secondary > primary ≈ tertiary (for phenyl substituted). Screening with other diazo compounds has shown that N(2)C(Ph)CO(2)Et displays similar reactivity to that of EDA, whereas other N(2)C(R)CO(2)Et (R = Me, CO(2)Et) gave lower conversions. PMID:23114570

  7. Polystyrene-supported triphenylarsines: Useful ligands in palladium-catalyzed aryl halide homocoupling reactions and a catalyst for alkene epoxidation using hydrogen peroxide

    OpenAIRE

    Song He, H; Zhang, C; Ng, CKW; Toy, PH

    2005-01-01

    The utility of both soluble (non-cross-linked) and insoluble (cross-linked) polystyrene-supported triphenylarsine reagents were examined. These reagents were prepared by standard radical polymerization methodology and used in palladium-catalyzed homocoupling reactions of aryl halides. The insoluble reagent was also used as a catalyst precursor in heterogeneous alkene epoxidation reactions in which aqueous hydrogen peroxide was the stoichiometric oxidant. For the aryl halide homocoupling react...

  8. Solar powered hydrogen generating facility and hydrogen powered vehicle fleet. Final technical report, August 11, 1994--January 6, 1997

    Energy Technology Data Exchange (ETDEWEB)

    Provenzano, J.J.

    1997-04-01

    This final report describes activities carried out in support of a demonstration of a hydrogen powered vehicle fleet and construction of a solar powered hydrogen generation system. The hydrogen generation system was permitted for construction, constructed, and permitted for operation. It is not connected to the utility grid, either for electrolytic generation of hydrogen or for compression of the gas. Operation results from ideal and cloudy days are presented. The report also describes the achievement of licensing permits for their hydrogen powered trucks in California, safety assessments of the trucks, performance data, and information on emissions measurements which demonstrate performance better than the Ultra-Low Emission Vehicle levels.

  9. Selective Oxidation of Toluene with Hydrogen Peroxide Catalyzed by V-Mo-based Catalyst

    Institute of Scientific and Technical Information of China (English)

    WU Jun-ping; WANG Xue-qin; ZHU Liang-fang; LI Gui-ying; HU Chang-wei

    2007-01-01

    The selective catalytic oxidation of toluene with hydrogen peroxide over V-Mo-based catalysts under mild conditions was studied. The promotion effect of Mo on the catalysts was studied with V/Al2O3 and Mo/Al2O3 as reference samples. The catalysts were characterized by XRD, TPR, and XPS techniques. The results show that the addition of Mo to V/Al2O3 may change the distribution of V species on Al2O3 surface. Over V-Mo/Al2O3 catalyst, highly dispersed amorphous V species facilitates benzaldehyde formation, and crystalline V2O5 species increases the conversion of toluene but decreases the selectivity to benzaldehyde, while AlVMoO7 species favors both the conversion of toluene and the formation of cresols. The yield of benzaldehyde depends remarkably on the surface O/Al and Mo/V atomic ratios, and gets to a maximum value of 13.2% with a selectivity of 79.5% at an O/Al atomic ratio of 3.0 and Mo/V atomic ratio of 0.7.

  10. Generator cooling hydrogen purity improvement system using hydrogen absorbing alloy; Suiso kyuzo gokin riyo hatsudenkinai suiso jundo kojo system

    Energy Technology Data Exchange (ETDEWEB)

    Takeda, H.; Kabutomori, T.; Wakisaka, Y. [Japan Steel Works, Ltd., Tokyo (Japan); Nishimura, Y.; Kogi, T.; Sato, J.; Haruki, N. [Kansai Electric Power Co. Inc., Osaka (Japan); Fujita, T. [Mitsubishi Electric Corp., Tokyo (Japan)

    1998-09-15

    Described herein is a system which uses a hydrogen-absorbing alloy to purify a hydrogen gas stream used as a coolant for power generator. Hydrogen in the stream containing impurities such as nitrogen can be selectively absorbed by sufficiently cooled hydrogen-absorbing alloy. Impurity gases concentrated in the alloy pores are released, and then the alloy is heated to release hydrogen. This purifies hydrogen to at least 99.99%. This system essentially consists of an hydrogen-absorbing unit, hot water production/supply system which circulates hot water of 80 to 90degC to release hydrogen out of the alloy, pretreatment unit, and temperature and pressure sensors. It is confirmed, by the test in which the system is connected to a commercial power generator of 600MW, that the system can be continuously operated to purify hydrogen to at least 99.9% for an extended period. 4 refs., 18 figs., 1 tab.

  11. Generation of hydrogen from photocatalytic cleavage of water

    Energy Technology Data Exchange (ETDEWEB)

    Mallinson, R.G.; Resasco, D.E.; Lobban, L.L.; Nicholas, K.M. [Univ. of Oklahoma, Norman, OK (United States)

    1998-08-01

    This paper describes the objectives, methods and early results on the US Department of Energy sponsored project to generate hydrogen from splitting of water using photocatalysts. The approach uses organometallic photosensitizers adsorbed onto platinated titania. Platinized titania is a photocatalyst for water splitting, but does not absorb sunlight in the visible range, where most of the sun`s energy is contained. Organometallic photosensitizers are synthesized, attached to platinized titania and characterized by UV-Vis spectroscopy, cyclic voltammetry, action spectra and hydrogen generation ability. Thus far, Copper, Iron and Ruthenium catalyst systems have been produced and characterized in this manner. Suitable sensitized systems that have the desirable properties have not yet been found.

  12. Hydrogenation of phenylpyruvic acid to phenylalanine catalyzed by Ni-B/SiO2

    Institute of Scientific and Technical Information of China (English)

    Qunfang Liang; Aiqing Zhang; Lin Li

    2008-01-01

    Phenylalanine(Phe)is a significant amino acid that cannot be synthesized by human themselves but must be taken from environment.It was initially found that the nanosized amorphous Ni-B/SiO2 alloy prepared by the chemical reduction method was an effective catalyst for the preparation of Phe from phenylpyruvic acid(PPA)by amination and hydrogenation.It has been found that the amorphous Ni-B/SiO2 alloy catalyst exhibits superior activity and selectivity to the traditional catalysts Raney Nj and Urushibara nickel.The effects of reaction time.amounts of catalysts and ammonia solution,reaction temperature,and H2 pressure on the reaction have been investigated systematically.The results indicated that the yield of Phe was 97.9%.and the selectivity for Phe reached 98.9%when the reaction was carried out for 3 h at 333 K and 2.0 Mpa of H2 with m(Cat.):m(PPA)=0.6:1.0 and n(NH3):n(PPA)=3:1.The catalysts were characterized by XRD,AAS,XPS,BET,and TEM.and the relationship between the catalyst structure and the catalytic activity was discussed in detail.It was found that the reason why Ni-B/SiO2 amorphous alloy catalyst was much more active for the preparation of Phe could be accounted for by the presence of electron-rich Ni due to electron donation from alloying B:the smaller size of Ni-B particles,the larger specific surface area of Ni-B/SiO2.

  13. Chemoselective and Sequential Palladium-Catalyzed Couplings for the Generation of Stilbene Libraries via Immobilized Substrates.

    Science.gov (United States)

    Traficante, Carla I; Fagundez, Catherine; Serra, Gloria L; Mata, Ernesto G; Delpiccolo, Carina M L

    2016-05-01

    A versatile palladium-catalyzed tandem synthetic sequence to afford E-stilbenes libraries has been developed. Excellent regio- and stereocontrol have been achieved by means of the sequence of Hiyama and Heck cross-couplings. Undesirable homocoupling byproducts were avoided employing immobilized substrates. PMID:27073985

  14. Hydrogen generation during molten-fuel-coolant interactions

    International Nuclear Information System (INIS)

    Given the absence of adequate cooling water to the core of a light-water reactor, the fission product decay heat would eventually cause the reactor fuel and cladding to melt. This could lead to slumping of the molten core materials into the lower plenum of the reactor vessel, possibly followed by failure of the vessel wall and pouring of the molten materials into the reactor cavity. Recent analyses have indicated that residual water is likely to be present both in the lower plenum and in the reactor cavity. Therefore, when the molten core materials enter either region, there is a strong probability of molten core contacting water. The physical process by which the molten core contacts and mixes with the water is important for two reasons: (1) because of its potential for rapid steam generation from a fuel-coolant interaction (FCI) either energetic or non-energetic; and (2) because it is a source of combustible hydrogen from the oxidation of the metallic components of the molten core. In this paper the rate of hydrogen generation due to fuel-coolant mixing is the major topic. To predict this one must understand two physical processes. The first is the degree of fuel breakup during the mixing phase and during the FCI. By understanding this process one is able to calculate the surface area available during the chemical reaction. The second is the rate of hydrogen generation per unit area when the fuel is molten and as it cools and solidifies

  15. GREEN CATALYZED OXIDATION OF HYDROCARBONS IN ALTERNATIVE SOLVENT SYSTEMS GENERATED BY PARIS II DECHEMA; GREEN SOLVENTS FOR CATALYSIS - ENVIRONMENTALLY BENIGN REACTION MEDIA

    Science.gov (United States)

    Green catalyzed oxidation of hydrocarbons in alternative solvent systems generated by PARIS IIThomas M. Becker, Michael A. Gonzalez, Paul F. Harten; Sustainable Technology Division, Office of Research and Development; United States Environmental Protection Agency, 26 West Mar...

  16. TEM analysis of the microstructure in TiF3-catalyzed and pure MgH2 during the hydrogen storage cycling

    International Nuclear Information System (INIS)

    We utilized transmission electron microscopy (TEM) analysis, with a cryogenically cooled sample stage, to detail the microstructure of partially transformed pure and titanium fluoride-catalyzed magnesium hydride powder during hydrogenation cycling. The TiF3-catalyzed MgH2 powder demonstrated excellent hydrogen storage kinetics at various temperatures, whereas the uncatalyzed MgH2 showed significant degradation in both kinetics and capacity. TEM analysis on the partially hydrogen absorbed and partially desorbed pure Mg(MgH2) revealed a large fraction of particles that were either not transformed at all or were completely transformed. On the other hand, in the MgH2+TiF3 system it was much easier to identify regions with both the hydride and the metal phase coexisting in the same particle. This enabled us to establish the metal hydride orientation relationship (OR) during hydrogen absorption. The OR was determined to be (1 1 0)MgH2 || (−1 1 0 −1)Mg and [−1 1 1]MgH2 || [0 1 −1 1]Mg. During absorption the number density of the hydride nuclei does not show a dramatic increase due the presence of TiF3. Conversely, during desorption the TiF3 catalyst substantially increases the number of the newly formed Mg crystallites, which display a strong texture correlation with respect to the parent MgH2 phase. Titanium fluoride also promotes extensive twinning in the hydride phase.

  17. A New Method for Generating Hydrogen from Water

    International Nuclear Information System (INIS)

    A new method for generating hydrogen by the reaction of Al powder with water using iodine as additive is developed. I2 can penetrate through the surface oxide layer on aluminium to form AlI3. High solubility of AlI3 in water is benefited to activate Al surface. It is found that the production of hydrogen becomes significant above 60° C and obeys a logarithm rule. The pH value varies from 5 to 3 then back to 4.5 during the reaction, which is determined mainly by the kinetics of hydration reaction of AlI3 and the reaction of Al and HI produced spontaneously. (cross-disciplinary physics and related areas of science and technology)

  18. Sum Frequency Generation Studies of Hydrogenation Reactions on Platinum Nanoparticles

    Energy Technology Data Exchange (ETDEWEB)

    Krier, James M. [Univ. of California, Berkeley, CA (United States)

    2013-08-31

    Sum Frequency Generation (SFG) vibrational spectroscopy is used to characterize intermediate species of hydrogenation reactions on the surface of platinum nanoparticle catalysts. In contrast to other spectroscopy techniques which operate in ultra-high vacuum or probe surface species after reaction, SFG collects information under normal conditions as the reaction is taking place. Several systems have been studied previously using SFG on single crystals, notably alkene hydrogenation on Pt(111). In this thesis, many aspects of SFG experiments on colloidal nanoparticles are explored for the first time. To address spectral interference by the capping agent (PVP), three procedures are proposed: UV cleaning, H2 induced disordering and calcination (core-shell nanoparticles). UV cleaning and calcination physically destroy organic capping while disordering reduces SFG signal through a reversible structural change by PVP.

  19. Nitric-glycolic flowsheet testing for maximum hydrogen generation rate

    Energy Technology Data Exchange (ETDEWEB)

    Martino, C. J. [Savannah River Site (SRS), Aiken, SC (United States). Savannah River National Lab. (SRNL); Newell, J. D. [Savannah River Site (SRS), Aiken, SC (United States). Savannah River National Lab. (SRNL); Williams, M. S. [Savannah River Site (SRS), Aiken, SC (United States). Savannah River National Lab. (SRNL)

    2016-03-01

    The Defense Waste Processing Facility (DWPF) at the Savannah River Site is developing for implementation a flowsheet with a new reductant to replace formic acid. Glycolic acid has been tested over the past several years and found to effectively replace the function of formic acid in the DWPF chemical process. The nitric-glycolic flowsheet reduces mercury, significantly lowers the chemical generation of hydrogen and ammonia, allows purge reduction in the Sludge Receipt and Adjustment Tank (SRAT), stabilizes the pH and chemistry in the SRAT and the Slurry Mix Evaporator (SME), allows for effective adjustment of the SRAT/SME rheology, and is favorable with respect to melter flammability. The objective of this work was to perform DWPF Chemical Process Cell (CPC) testing at conditions that would bound the catalytic hydrogen production for the nitric-glycolic flowsheet.

  20. A New Method for Generating Hydrogen from Water

    Institute of Scientific and Technical Information of China (English)

    MENG Qing-Bo; LI Ke-Xin; LI Hong; FAN Yu-Zun; YU Zhe-Xun; LI Dong-Mei; LUO Yan-Hong; CHEN Li-Quan

    2008-01-01

    A new method for generating hydrogen by the reaction of A1 powder with water using iodine as additive is developed. 12 can penetrate through the surface oxide layer on atuminium to form AlI3. High solubility of AlI3 in water is benefited to activate Al surface. It is found that the production of hydrogen becomes significant above 60℃ and obeys a logarithm rule. The pH value varies from 5 to 3 then back to 4.5 during the reaction,which is determined mainly by the kinetics of hydration reaction of AlI3 and the reaction of Al and HI produced spontaneously.

  1. Atomistic Modelling of Materials for Clean Energy Applications : hydrogen generation, hydrogen storage, and Li-ion battery

    OpenAIRE

    Qian, Zhao

    2013-01-01

    In this thesis, a number of clean-energy materials for hydrogen generation, hydrogen storage, and Li-ion battery energy storage applications have been investigated through state-of-the-art density functional theory. As an alternative fuel, hydrogen has been regarded as one of the promising clean energies with the advantage of abundance (generated through water splitting) and pollution-free emission if used in fuel cell systems. However, some key problems such as finding efficient ways to prod...

  2. Converting Chemical Energy to Electricity through a Three-Jaw Mini-Generator Driven by the Decomposition of Hydrogen Peroxide.

    Science.gov (United States)

    Xiao, Meng; Wang, Lei; Ji, Fanqin; Shi, Feng

    2016-05-11

    Energy conversion from a mechanical form to electricity is one of the most important research advancements to come from the horizontal locomotion of small objects. Until now, the Marangoni effect has been the only propulsion method to produce the horizontal locomotion to induce an electromotive force, which is limited to a short duration because of the specific property of surfactants. To solve this issue, in this article we utilized the decomposition of hydrogen peroxide to provide the propulsion for a sustainable energy conversion from a mechanical form to electricity. We fabricated a mini-generator consisting of three parts: a superhydrophobic rotator with three jaws, three motors to produce a jet of oxygen bubbles to propel the rotation of the rotator, and three magnets integrated into the upper surface of the rotator to produce the magnet flux. Once the mini-generator was placed on the solution surface, the motor catalyzed the decomposition of hydrogen peroxide. This generated a large amount of oxygen bubbles that caused the generator and integrated magnets to rotate at the air/water interface. Thus, the magnets passed under the coil area and induced a change in the magnet flux, thus generating electromotive forces. We also investigated experimental factors, that is, the concentration of hydrogen peroxide and the turns of the solenoid coil, and found that the mini-generator gave the highest output in a hydrogen peroxide solution with a concentration of 10 wt % and under a coil with 9000 turns. Through combining the stable superhydrophobicity and catalyst, we realized electricity generation for a long duration, which could last for 26 000 s after adding H2O2 only once. We believe this work provides a simple process for the development of horizontal motion and provides a new path for energy reutilization. PMID:27093949

  3. Ex Situ Generation of Stoichiometric and Substoichiometric 12CO and 13CO and Its Efficient Incorporation in Palladium Catalyzed Aminocarbonylations

    DEFF Research Database (Denmark)

    Hermange, Philippe; Lindhardt, Anders Thyboe; Taaning, Rolf Hejle;

    2011-01-01

    chlorides using a catalyst originating from Pd(dba)2 and P(tBu)3. Preliminary studies using pivaloyl chloride as the CO-precursor provided an alternative approach for the aminocarbonylation of 2-pyridyl tosylate derivatives using only 1.5 equiv of CO. Further design of the acid chloride CO-precursor led to...... with studies aimed toward application of CO as the limiting reagent, this method provided highly efficient palladium catalyzed aminocarbonylations with CO-incorporations up to 96%. The ex situ generated CO and the two-chamber system were tested in the synthesis of several compounds of pharmaceutical......, which is safely handled and stored. Furthermore, since the CO is generated ex situ, excellent functional group tolerance is secured in the carbonylation chamber. Finally, CO is only generated and released in minute amounts, hence, eliminating the need for specialized equipment such as CO-detectors and...

  4. Extreme hydrogen plasma densities achieved in a linear plasma generator

    International Nuclear Information System (INIS)

    A magnetized hydrogen plasma beam was generated with a cascaded arc, expanding in a vacuum vessel at an axial magnetic field of up to 1.6 T. Its characteristics were measured at a distance of 4 cm from the nozzle: up to a 2 cm beam diameter, 7.5x1020 m-3 electron density, ∼2 eV electron and ion temperatures, and 3.5 km/s axial plasma velocity. This gives a 2.6x1024 H+ m-2 s-1 peak ion flux density, which is unprecedented in linear plasma generators. The high efficiency of the source is obtained by the combined action of the magnetic field and an optimized nozzle geometry. This is interpreted as a cross-field return current that leads to power dissipation in the beam just outside the source

  5. Nano-hetero functional materials for photocatalytic hydrogen generation

    Science.gov (United States)

    Tongying, Pornthip

    This dissertation focuses on designing nanomaterials and investigating their photocatalytic response for H2 generation. Hydrogen has gained a lot of attention as a new source of sustainable energy. It can be used to directly generate power in fuel cells and to produce liquid fuels such as methanol. Water splitting is an ideal (clean) way of producing H2 because it uses water and sunlight, two renewable resources. To explore the use of nanostructures and particularly nanostructure heterojunctions for photocatalytic H2 generation, four different systems have been synthesized: (i) CdSe nanowires (NWs), (ii) CdSe/CdS core/shell NWs, (iii) CdSe NWs decorated with Au or Pt nanoparticles, and (iv) CdSe/CdS NWs decorated with Au or Pt nanoparticles. This is motivated by (a) the fact that CdSe NWs absorb light from the UV to the near infrared (b) the NW morphology simultaneously enables us to explore the role of nanoscale dimensionality in photocatalytic processes (c) a CdS coating can enhance photogenerated carrier lifetimes, and (d) metal nanoparticles are catalytically active and can also enhance charge separation efficiencies. Charge separation and charge transfer across interfaces are key aspects in the design of efficient photocatalysts for solar energy conversion. Femtosecond transient differential absorption (TDA) spectroscopy has been used as a tool to reveal how semiconductor/semiconductor and metal/semiconductor heterojunctions affect the charge separation and hydrogen generation efficiencies of these hybrid photocatalysts. The use of this technique in concert with hydrogen evolution tests also reveal how CdS, CdSe and metal NP interact within metal NP decorated CdSe and CdSe/CdS NWs during photocatalytic hydrogen generation reactions. Electron transfer events across both semiconductor/semiconductor and metal/semiconductor heterojunctions are followed to identify where H 2 is evolved and the role each heterojunction plays in determining a system's overall

  6. HYDROGEN GENERATION FROM ELECTROLYSIS - REVISED FINAL TECHNICAL REPORT

    Energy Technology Data Exchange (ETDEWEB)

    IBRAHIM, SAMIR; STICHTER, MICHAEL

    2008-07-31

    DOE GO13028-0001 DESCRIPTION/ABSTRACT This report is a summary of the work performed by Teledyne Energy Systems to understand high pressure electrolysis mechanisms, investigate and address safety concerns related to high pressure electrolysis, develop methods to test components and systems of a high pressure electrolyzer, and produce design specifications for a low cost high pressure electrolysis system using lessons learned throughout the project. Included in this report are data on separator materials, electrode materials, structural cell design, and dissolved gas tests. Also included are the results of trade studies for active area, component design analysis, high pressure hydrogen/oxygen reactions, and control systems design. Several key pieces of a high pressure electrolysis system were investigated in this project and the results will be useful in further attempts at high pressure and/or low cost hydrogen generator projects. An important portion of the testing and research performed in this study are the safety issues that are present in a high pressure electrolyzer system and that they can not easily be simplified to a level where units can be manufactured at the cost goals specified, or operated by other than trained personnel in a well safeguarded environment. The two key objectives of the program were to develop a system to supply hydrogen at a rate of at least 10,000 scf/day at a pressure of 5000psi, and to meet cost goals of $600/ kW in production quantities of 10,000/year. On these two points TESI was not successful. The project was halted due to concerns over safety of high pressure gas electrolysis and the associated costs of a system which reduced the safety concerns.

  7. Transfer Hydrogenation of C= C Double Bonds Catalyzed by Ruthenium Amido-Complexes:Scopes, Limitation and Enantioselectivity

    Institute of Scientific and Technical Information of China (English)

    XUE,Dong; CHENG,Ying-Chun; CUI,Xin; WANG,Qi-Wei; ZHU,Jin; DENG,Jin-Gen

    2004-01-01

    @@ The reduction of C = C double bonds is one of the most fundamental synthetic transformations and plays a key role in the manufacturing of a wide variety of bulk and fine chemicals. Hydrogenation of olefinic substrates can be achieved readily with molecular hydrogen in many cases, but transfer hydrogenation methods using suitable donor molecules such as formic acid or alcohols are receiving increasing attention as possible synthetic alternatives because it requires no special equipment and avoids the handling of potentially hazardous gaseous hydrogen.

  8. Photocatalytic Hydrogen Generation by CdSe/CdS Nanoparticles.

    Science.gov (United States)

    Qiu, Fen; Han, Zhiji; Peterson, Jeffrey J; Odoi, Michael Y; Sowers, Kelly L; Krauss, Todd D

    2016-09-14

    The photocatalytic hydrogen (H2) production activity of various CdSe semiconductor nanoparticles was compared including CdSe and CdSe/CdS quantum dots (QDs), CdSe quantum rods (QRs), and CdSe/CdS dot-in-rods (DIRs). With equivalent photons absorbed, the H2 generation activity orders as CdSe QDs ≫ CdSe QRs > CdSe/CdS QDs > CdSe/CdS DIRs, which is surprisingly the opposite of the electron-hole separation efficiency. Calculations of photoexcited surface charge densities are positively correlated with the H2 production rate and suggest the size of the nanoparticle plays a critical role in determining the relative efficiency of H2 production. PMID:27478995

  9. Broad Spectrum Photoelectrochemical Diodes for Solar Hydrogen Generation

    Energy Technology Data Exchange (ETDEWEB)

    Grimes, Craig A.

    2014-11-26

    Under program auspices we have investigated material chemistries suitable for the solar generation of hydrogen by water photoelectrolysis. We have built upon, and extended, our knowledge base on the synthesis and application of TiO2 nanotube arrays, a material architecture that appears ideal for water photoelectrolysis. To date we have optimized, refined, and greatly extended synthesis techniques suitable for achieving highly ordered TiO2 nanotube arrays of given length, wall thickness, pore diameter, and tube-to-tube spacing for use in water photoelectrolysis. We have built upon this knowledge based to achieve visible light responsive, photocorrosion stable n-type and p-type ternary oxide nanotube arrays for use in photoelectrochemical diodes.

  10. Nitrogen-Doped Graphene for Photocatalytic Hydrogen Generation.

    Science.gov (United States)

    Chang, Dong Wook; Baek, Jong-Beom

    2016-04-20

    Photocatalytic hydrogen (H2 ) generation in a water splitting process has recently attracted tremendous interest because it allows the direct conversion of clean and unlimited solar energy into the ideal energy resource of H2 . For efficient photocatalytic H2 generation, the role of the photocatalyst is critical. With increasing demand for more efficient, sustainable, and cost-effective photocatalysts, various types of semiconductor photocatalysts have been intensively developed. In particular, on the basis of its superior catalytic and tunable electronic properties, nitrogen-doped graphene is a potential candidate for a high-performance photocatalyst. Nitrogen-doped graphene also offers additional advantages originating from its unique two-dimensional sp(2) -hybridized carbon network including a large specific surface area and exceptional charge transport properties. It has been reported that nitrogen-doped graphene can play diverse but positive functions including photo-induced charge acceptor/meditator, light absorber from UV to visible light, n-type semiconductor, and giant molecular photocatalyst. Herein, we summarize the recent progress and general aspects of nitrogen-doped graphene as a photocatalyst for photocatalytic H2 generation. In addition, challenges and future perspectives in this field are also discussed. PMID:26762892

  11. Manganese(II) catalyzes the bicarbonate-dependent oxidation of amino acids by hydrogen peroxide and the amino acid-facilitated dismutation of hydrogen peroxide.

    OpenAIRE

    Berlett, B S; Chock, P B; Yim, M B; Stadtman, E. R.

    1990-01-01

    In bicarbonate/CO2 buffer, Mn(II) and Fe(II) catalyze the oxidation of amino acids by H2O2 and the dismutation of H2O2. As the Mn(II)/Fe(II) ratio is increased, the yield of carbonyl compounds per mole of leucine oxidized is essentially constant, but the ratio of alpha-ketoisocaproate to isovaleraldehyde formed increases, and the fraction of H2O2 converted to O2 increases. In the absence of Fe(II), the rate of Mn(II)-catalyzed leucine oxidation is directly proportional to the H2O2, Mn(II), an...

  12. Development of a new hydrogen purification system by using hydrogen absorbing alloy for generator cooling; Suiso kyuzo gokin riyo hatsudenkinai suiso jundo kojo system no kaihatsu

    Energy Technology Data Exchange (ETDEWEB)

    Haruki, N.; Sato, J.; Kogi, T.; Nishimura, Y. [Kansai Electric Power Co., Inc., Osaka (Japan); Takeda, H. [Japan Steel works Ltd., Tokyo (Japan)] Fujita, T. [Mitsubishi Electric Corp., Tokyo (Japan)

    1997-05-20

    Hydrogen absorbing alloys have a number of useful functions, such as energy conversion, hydrogen storage and purification. As an application to separation and purification of hydrogen, we have developed a new hydrogen purification system by using a hydrogen absorbing alloy for generator cooling. For demonstration testing with an actual machine, a hydrogen recovery and purification device using 120kg of alloy was manufactured and installed on No.5 turbine-synchronous generator at Himeji No.2 power station. This device is designed to improve the purity of the hydrogen gas in generator containing impurities such as nitrogen and oxygen. The test results tell that the purity of the hydrogen gas in the generator can be enhanced from 98% to 99.9% and maintained at this level under continuous operation. An application of the hydrogen purification system is expected to decrease the generator`s windage loss, resulting higher generator efficiency. 2 refs., 18 figs.

  13. Selective electrochemical generation of hydrogen peroxide from water oxidation

    OpenAIRE

    Viswanathan, Venkatasubramanian; Hansen, Heine A.; Nørskov, Jens K.

    2015-01-01

    Water is a life-giving source, fundamental to human existence, yet, over a billion people lack access to clean drinking water. Present techniques for water treatment such as piped, treated water rely on time and resource intensive centralized solutions. In this work, we propose a decentralized device concept that can utilize sunlight to split water into hydrogen and hydrogen peroxide. The hydrogen peroxide can oxidize organics while the hydrogen bubbles out. In enabling this device, we requir...

  14. Spark Discharge Generated Nanoparticles for Hydrogen Storage Applications

    NARCIS (Netherlands)

    Vons, V.A.

    2010-01-01

    One of the largest obstacles to the large scale application of hydrogen powered fuel cell vehicles is the absence of hydrogen storage methods suitable for application on-board of these vehicles. Metal hydrides are materials in which hydrogen is reversibly absorbed by one or more metals or combinatio

  15. Ruthenium-Catalyzed Asymmetric Hydrohydroxyalkylation of Butadiene: The Role of the Formyl Hydrogen Bond in Stereochemical Control

    Science.gov (United States)

    Grayson, Matthew N.; Krische, Michael J.; Houk, K. N.

    2016-01-01

    The catalyst generated in situ from RuH2(CO)(PPh3)3, (S)-SEGPHOS, and a chiral phosphoric acid promotes asymmetric hydrohydroxyalkylation of butadiene and affords enantioenriched α-methyl homoallylic alcohols. The observed diastereo- and enantioselectivities are determined by both the chiral phosphine and chiral phosphate ligands. Density functional theory calculations (M06/SDD-6-311G(d,p)-IEFPCM(acetone)//B3LYP/SDD-6-31G(d)) predict that the product distribution is controlled by the kinetics of carbon-carbon bond formation, and this process occurs via a closed-chair Zimmerman-Traxler-type transition structure (TS). Chiral phosphate-dependent stereoselectivity arising from this TS is enabled through a hydrogen bond between the phosphoryl oxygen and the aldehyde formyl proton present in TADDOL-derived catalysts. This interaction is absent in the corresponding BINOL-derived systems and the opposite sense of attack on the aldehyde occurs. Additional factors influencing stereochemical control are determined. PMID:26107070

  16. Generation mechanism of hydrogen gas from hardened cement paste by γ-irradiation

    International Nuclear Information System (INIS)

    Hydrogen gas is generated from cementitious waste forms by radiolysis of water. In the case of low level radioactive waste, gas yields have been confirmed to be sufficiently low by irradiation experiments. However, studies have suggested that the hydrogen generation rate in cementitious waste forms is larger than the rate calculated form the g-value (H2 yields for 100eV absorbed). In this paper, the factors that increase the gas generation were investigated quantitatively. Two factors were identified, the effect of an organic diethylene glycol which reacts with hydrogen radicals to produce hydrogen, and the effect of electrons generated in the cementitious matrix which decompose water to hydrogen. The hydrogen generation rate was confirmed to drop less than the rate calculated from the g-value when these factors were eliminated

  17. Justification procedure of hydrogen safety of RU BN compartments as exemplified by steam generator box

    International Nuclear Information System (INIS)

    Basic proposals on completing calculational procedures of sodium cooled reactors hydrogen safety justification, particularly steam generator (SG) box, are presented. It is pointed out that hydrogen appearance in SG box is possible only in accidents with multiple failures. The data presented shows that hydrogen safety and explosion-proofness of fast reactor facility SG box are provided without any special complex and expensive means

  18. Computational design of materials for solar hydrogen generation

    Science.gov (United States)

    Umezawa, Naoto

    Photocatalysis has a great potential for the production of hydrogen from aquerous solution under solar light. In this talk, two different approaches toward the computational materials desing for solar hydrogen generation will be presented. Tin (Sn), which has two major oxidation states, Sn2+ and Sn4+, is abundant on the earth's crust. Recently, visible-light responsive photocatalytc H2 evolution reaction was identified over a mixed valence tin oxide Sn3O4. We have carried out crystal structure prediction for mixed valence tin oxides in different atomic compositions under ambient pressure condition using advanced computational methods based on the evolutionary crystal-structure search and density-functional theory. The predicted novel crystal structures realize the desirable band gaps and band edge positions for H2 evolution under visible light irradiation. It is concluded that multivalent tin oxides have a great potential as an abundant, cheap and environmentally-benign solar-energy conversion photofunctional materials. Transition metal doping is effective for sensitizing SrTiO3 under visible light. We have theoretically investigated the roles of the doped Cr in STO based on hybrid density-functional calculations. Cr atoms are preferably substituting for Ti under any equilibrium growth conditions. The lower oxidation state Cr3+, which is stabilized under an n-type condition of STO, is found to be advantageous for the photocatalytic performance. It is firther predicted that lanthanum is the best codopant for stabilizing the favorable oxidation state, Cr3+. The prediction was validated by our experiments that La and Cr co-doped STO shows the best performance among examined samples. This work was supported by the Japan Science and Technology Agency (JST) Precursory Research for Embryonic Science and Technology (PRESTO) and International Research Fellow program of Japan Society for the Promotion of Science (JSPS) through project P14207.

  19. GaN growth using gallium hydride generated by hydrogenation of liquid gallium

    Science.gov (United States)

    Nagayoshi, H.; Nishimura, S.; Takeuchi, T.; Hirai, M.; Terashima, K.

    2005-02-01

    The novel growth method of GaN using hydrogen radicals has been investigated. This paper is the first report of gallium hydrogenation reaction and deposition of GaN using hydrogenated gallium. We found that gallium (Ga) could be volatilized at low temperature by hydrogenation reaction with hydrogen radicals. In this reaction, Ga assumed to be volatilized as GaH 3. The GaN deposition was attempted by using gas phase reaction of NH 3 and GaH 3 generated by the reaction between liquid Ga and hydrogen radicals. Hydrogen radicals were generated by hot tungsten filament, which works as a catalyst during hydrogen cracking, whose temperature was 1600 °C. Surface morphology, deposition rate, and film structure were investigated. It was confirmed that GaN could be deposited by this method. The source materials of this method are safe and of low cost compared to the conventional methods.

  20. Heterogeneous platinum-catalyzed hydrogenation of dialkyl(diolefin)platinum(II) complexes: A new route to platinum surface alkyls

    OpenAIRE

    McCarthy, Thomas J.; Shih, Yen-Shiang; Whitesides, George M.

    1981-01-01

    Platinum metal catalyzes the reduction of dialkyl(diolefin)platinum(II) complexes by dihydrogen to alkanes and platinum(0). The reaction involves adsorption of the platinum(II) complex on the platinum(0) catalyst surface with conversion of the alkyl moieties to platinum surface alkyls; these appear as alkane products. The platinum atom originally present in the soluble organoplatinum species becomes part of the platinum(0) surface.

  1. Atmospheric Hydrogenation of Esters Catalyzed by PNP-Ruthenium Complexes with an N-Heterocyclic Carbene Ligand.

    Science.gov (United States)

    Ogata, Osamu; Nakayama, Yuji; Nara, Hideki; Fujiwhara, Mitsuhiko; Kayaki, Yoshihito

    2016-08-01

    New pincer ruthenium complexes bearing a monodentate N-heterocyclic carbene ligand were synthesized and demonstrated as powerful hydrogenation catalysts. With an atmospheric pressure of hydrogen gas, aromatic, heteroaromatic, and aliphatic esters as well as lactones were converted into the corresponding alcohols at 50 °C. This reaction protocol offers reliable access to alcohols using an easy operational setup. PMID:27439106

  2. Dependable Hydrogen and Industrial Heat Generation from the Next Generation Nuclear Plant

    Energy Technology Data Exchange (ETDEWEB)

    Charles V. Park; Michael W. Patterson; Vincent C. Maio; Piyush Sabharwall

    2009-03-01

    The Department of Energy is working with industry to develop a next generation, high-temperature gas-cooled nuclear reactor (HTGR) as a part of the effort to supply the US with abundant, clean and secure energy. The Next Generation Nuclear Plant (NGNP) project, led by the Idaho National Laboratory, will demonstrate the ability of the HTGR to generate hydrogen, electricity, and high-quality process heat for a wide range of industrial applications. Substituting HTGR power for traditional fossil fuel resources reduces the cost and supply vulnerability of natural gas and oil, and reduces or eliminates greenhouse gas emissions. As authorized by the Energy Policy Act of 2005, industry leaders are developing designs for the construction of a commercial prototype producing up to 600 MWt of power by 2021. This paper describes a variety of critical applications that are appropriate for the HTGR with an emphasis placed on applications requiring a clean and reliable source of hydrogen. An overview of the NGNP project status and its significant technology development efforts are also presented.

  3. DMFC at low air flow operation: Study of parasitic hydrogen generation

    International Nuclear Information System (INIS)

    In this paper, the effect of hydrogen generation in direct methanol fuel cells (DMFC) is described. Under certain operating conditions hydrogen generation occurs in DMFC causing an additional methanol consumption and a decrease of the cell voltage. For the present experiments a segmented cell with an active area of 244 cm2 is used. The cell has 196 segments which are regularly distributed on the whole area. By this experimental setup hydrogen generation was found in regions with insufficient air supply. Hydrogen generation was analyzed by systematically applying different air flow rates and detecting the local current densities. The theory for hydrogen generation is confirmed by the results obtained from the segmented cell. A correlation between open circuit voltage (OCV), air flow rate and hydrogen generation was observed. Furthermore, half-cell measurements with different methanol concentrations were performed and used for analyzing the processes during hydrogen generation. The work clearly indicates the importance of sufficient cathode air supply for DMFC. Starved cathode areas not only do not contribute to the overall current generation but in addition reduce the power and efficiency by the parasitic generation of hydrogen

  4. Integrated photoelectrochemical energy storage: solar hydrogen generation and supercapacitor

    Science.gov (United States)

    Xia, Xinhui; Luo, Jingshan; Zeng, Zhiyuan; Guan, Cao; Zhang, Yongqi; Tu, Jiangping; Zhang, Hua; Fan, Hong Jin

    2012-01-01

    Current solar energy harvest and storage are so far realized by independent technologies (such as solar cell and batteries), by which only a fraction of solar energy is utilized. It is highly desirable to improve the utilization efficiency of solar energy. Here, we construct an integrated photoelectrochemical device with simultaneous supercapacitor and hydrogen evolution functions based on TiO2/transition metal hydroxides/oxides core/shell nanorod arrays. The feasibility of solar-driven pseudocapacitance is clearly demonstrated, and the charge/discharge is indicated by reversible color changes (photochromism). In such an integrated device, the photogenerated electrons are utilized for H2 generation and holes for pseudocapacitive charging, so that both the reductive and oxidative energies are captured and converted. Specific capacitances of 482 F g−1 at 0.5 A g−1 and 287 F g−1 at 1 A g−1 are obtained with TiO2/Ni(OH)2 nanorod arrays. This study provides a new research strategy for integrated pseudocapacitor and solar energy application. PMID:23248745

  5. Hydrogen Plasma Generation with 200 MHz RF Ion Source

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Jeongtae; Park, Kwangmook; Seo, Dong Hyuk; Kim, Han-Sung; Kwon, Hyeok-Jung; Cho, Yong-Sub [Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of)

    2014-10-15

    The ion source for the system is required to be rugged with 2000 hours maintenance free operation time because it is installed in the vessel filled with SF6 gas at the pressure of 10 bar. A 200 MHz RF ion source is considered as an ion source. It is a simple construction and provides long life operation. The specifications of the ion source are 5 kV extraction voltage and 1 mA beam current referenced to the proton. RF ion source has been developed and undergone a performance test. Results of the test are presented. 200 MHz RF ion source is designated and manufactured. First of all test stand test of ion source are set up for a performance test of ion source. It includes a RF ion source, a 200-MHz RF system, beam extraction system, vacuum system, beam extraction system, and beam diagnostic system. At pressure of 1.2E-5 torr, hydrogen plasma is generated with net RF power 70 W. Pyrex tube surrounded by an inductive coil takes the role of vessel and discharge is enhanced with field of permanent magnets.

  6. Durable pd-based alloy and hydrogen generation membrane thereof

    Science.gov (United States)

    Benn, Raymond C.; Opalka, Susanne M.; Vanderspurt, Thomas Henry

    2010-02-02

    A durable Pd-based alloy is used for a H.sub.2-selective membrane in a hydrogen generator, as in the fuel processor of a fuel cell plant. The Pd-based alloy includes Cu as a binary element, and further includes "X", where "X" comprises at least one metal from group "M" that is BCC and acts to stabilize the .beta. BCC phase for stability during operating temperatures. The metal from group "M" is selected from the group consisting of Fe, Cr, Nb, Ta, V, Mo, and W, with Nb and Ta being most preferred. "X" may further comprise at least one metal from a group "N" that is non-BCC, preferably FCC, that enhances other properties of the membrane, such as ductility. The metal from group "N" is selected from the group consisting of Ag, Au, Re, Ru, Rh, Y, Ce, Ni, Ir, Pt, Co, La and In. The at. % of Pd in the binary Pd--Cu alloy ranges from about 35 at. % to about 55 at. %, and the at. % of "X" in the higher order alloy, based on said binary alloy, is in the range of about 1 at. % to about 15 at. %. The metals are selected according to a novel process.

  7. A Study of Cooperative Operation of Wind Energy Conversion System with Hydrogen Electrolyzer by using Adjustable Speed Flywheel Generator

    Science.gov (United States)

    Nobuta, Masaaki; Takahashi, Rion; Murata, Toshiaki; Tamura, Junji; Sugimasa, Masatoshi; Komura, Akiyoshi; Futami, Motoo; Ichinose, Masaya; Ide, Kazumasa

    Hydrogen is considered as the energy source of the next generation. This paper proposes a system which consists of FlyWheel Generator (FWG), Wind Energy Conversionr System (WECS), and Hydrogen Electrolyzer (HE), for the purpose of hydrogen generation and grid output power smoothing. The cooperative control among flywheel generator, hydrogen electrolyzer, and wind generator is performed by controlling the flywheel generator. Simulations have been done by PSCAD/EMTDC.

  8. Robust and Porous β-Diketiminate-Functionalized Metal–Organic Frameworks for Earth-Abundant-Metal-Catalyzed C–H Amination and Hydrogenation

    Energy Technology Data Exchange (ETDEWEB)

    Thacker, Nathan C.; Lin, Zekai; Zhang, Teng; Gilhula, James C.; Abney, Carter W.; Lin, Wenbin (UC)

    2016-05-27

    We have designed a strategy for postsynthesis installation of the β-diketiminate (NacNac) functionality in a metal–organic framework (MOF) of UiO-topology. Metalation of the NacNac-MOF (I) with earth-abundant metal salts afforded the desired MOF-supported NacNac-M complexes (M = Fe, Cu, and Co) with coordination environments established by detailed EXAFS studies. The NacNac-Fe-MOF catalyst, I•Fe(Me), efficiently catalyzed the challenging intramolecular sp3 C–H amination of a series of alkyl azides to afford α-substituted pyrrolidines. The NacNac-Cu-MOF catalyst, I•Cu(THF), was effective in promoting the intermolecular sp3 C–H amination of cyclohexene using unprotected anilines to provide access to secondary amines in excellent selectivity. Finally, the NacNac-Co-MOF catalyst, I•Co(H), was used to catalyze alkene hydrogenation with turnover numbers (TONs) as high as 700 000. All of the NacNac-M-MOF catalysts were more effective than their analogous homogeneous catalysts and could be recycled and reused without a noticeable decrease in yield. The NacNac-MOFs thus provide a novel platform for engineering recyclable earth-abundant-element-based single-site solid catalysts for many important organic transformations.

  9. Effective hydrogen generation and resource circulation based on sulfur cycle system

    Energy Technology Data Exchange (ETDEWEB)

    Takahashi, Hideyuki; Mabuchi, Takashi; Hayashi, Tsugumi; Yokoyama, Shun; Tohji, Kazuyuki [Graduate School of Environmental Studies, Tohoku University 6-6-20, Aramaki, Aoba-ku, Sendai, 980-8579 (Japan)

    2013-12-10

    For the effective hydrogen generation from H{sub 2}S, it should be compatible that the increscent of the photocatalytic (or electrochemical) activities and the development of effective utilization method of by-products (poly sulfide ion). In this study, “system integration” to construct the sulfur cycle system, which is compatible with the increscent of the hydrogen and or electron energy generation ratio and resource circulation, is investigated. Photocatalytic hydrogen generation rate can be enhanced by using stratified photocatalysts. Photo excited electron can be transpired to electrode to convert the electron energy to hydrogen energy. Poly sulfide ion as the by-products can be transferred into elemental sulfur and/or industrial materials such as rubber. Moreover, elemental sulfur can be transferred into H{sub 2}S which is the original materials for hydrogen generation. By using this “system integration”, the sulfur cycle system for the new energy generation can be constructed.

  10. Effective hydrogen generation and resource circulation based on sulfur cycle system

    International Nuclear Information System (INIS)

    For the effective hydrogen generation from H2S, it should be compatible that the increscent of the photocatalytic (or electrochemical) activities and the development of effective utilization method of by-products (poly sulfide ion). In this study, “system integration” to construct the sulfur cycle system, which is compatible with the increscent of the hydrogen and or electron energy generation ratio and resource circulation, is investigated. Photocatalytic hydrogen generation rate can be enhanced by using stratified photocatalysts. Photo excited electron can be transpired to electrode to convert the electron energy to hydrogen energy. Poly sulfide ion as the by-products can be transferred into elemental sulfur and/or industrial materials such as rubber. Moreover, elemental sulfur can be transferred into H2S which is the original materials for hydrogen generation. By using this “system integration”, the sulfur cycle system for the new energy generation can be constructed

  11. Hydrogen generation via photoelectrochemical water splitting using chemically exfoliated MoS2 layers

    Science.gov (United States)

    Joshi, R. K.; Shukla, S.; Saxena, S.; Lee, G.-H.; Sahajwalla, V.; Alwarappan, S.

    2016-01-01

    Study on hydrogen generation has been of huge interest due to increasing demand for new energy sources. Photoelectrochemical reaction by catalysts was proposed as a promising technique for hydrogen generation. Herein, we report the hydrogen generation via photoelectrochecmial reaction using films of exfoliated 2-dimensional (2D) MoS2, which acts as an efficient photocatalyst. The film of chemically exfoliated MoS2 layers was employed for water splitting, leading to hydrogen generation. The amount of hydrogen was qualitatively monitored by observing overpressure of a water container. The high photo-current generated by MoS2 film resulted in hydrogen evolution. Our work shows that 2D MoS2 is one of the promising candidates as a photocatalyst for light-induced hydrogen generation. High photoelectrocatalytic efficiency of the 2D MoS2 shows a new way toward hydrogen generation, which is one of the renewable energy sources. The efficient photoelectrocatalytic property of the 2D MoS2 is possibly due to availability of catalytically active edge sites together with minimal stacking that favors the electron transfer.

  12. Hydrogen generation via photoelectrochemical water splitting using chemically exfoliated MoS{sub 2} layers

    Energy Technology Data Exchange (ETDEWEB)

    Joshi, R. K., E-mail: r.joshi@unsw.edu.au, E-mail: alwarappan@cecri.res.in; Sahajwalla, V. [Centre for Sustainable Materials Research and Technology, School of Materials Science and Engineering, University of New South Wales, NSW 2052 (Australia); Shukla, S.; Saxena, S. [Department of Metallurgical Engineering and Materials Science, Indian Institute of Technology Bombay, Mumbai (India); Lee, G.-H. [Department of Material Science and Engineering, Yonsei University, Seoul 120-749 (Korea, Republic of); Alwarappan, S., E-mail: r.joshi@unsw.edu.au, E-mail: alwarappan@cecri.res.in [CSIR-Central Electrochemical Research Institute, Karaikudi 630006, Tamilnadu (India)

    2016-01-15

    Study on hydrogen generation has been of huge interest due to increasing demand for new energy sources. Photoelectrochemical reaction by catalysts was proposed as a promising technique for hydrogen generation. Herein, we report the hydrogen generation via photoelectrochecmial reaction using films of exfoliated 2-dimensional (2D) MoS{sub 2}, which acts as an efficient photocatalyst. The film of chemically exfoliated MoS{sub 2} layers was employed for water splitting, leading to hydrogen generation. The amount of hydrogen was qualitatively monitored by observing overpressure of a water container. The high photo-current generated by MoS{sub 2} film resulted in hydrogen evolution. Our work shows that 2D MoS{sub 2} is one of the promising candidates as a photocatalyst for light-induced hydrogen generation. High photoelectrocatalytic efficiency of the 2D MoS{sub 2} shows a new way toward hydrogen generation, which is one of the renewable energy sources. The efficient photoelectrocatalytic property of the 2D MoS{sub 2} is possibly due to availability of catalytically active edge sites together with minimal stacking that favors the electron transfer.

  13. Hydrogen generation via photoelectrochemical water splitting using chemically exfoliated MoS2 layers

    Directory of Open Access Journals (Sweden)

    R. K. Joshi

    2016-01-01

    Full Text Available Study on hydrogen generation has been of huge interest due to increasing demand for new energy sources. Photoelectrochemical reaction by catalysts was proposed as a promising technique for hydrogen generation. Herein, we report the hydrogen generation via photoelectrochecmial reaction using films of exfoliated 2-dimensional (2D MoS2, which acts as an efficient photocatalyst. The film of chemically exfoliated MoS2 layers was employed for water splitting, leading to hydrogen generation. The amount of hydrogen was qualitatively monitored by observing overpressure of a water container. The high photo-current generated by MoS2 film resulted in hydrogen evolution. Our work shows that 2D MoS2 is one of the promising candidates as a photocatalyst for light-induced hydrogen generation. High photoelectrocatalytic efficiency of the 2D MoS2 shows a new way toward hydrogen generation, which is one of the renewable energy sources. The efficient photoelectrocatalytic property of the 2D MoS2 is possibly due to availability of catalytically active edge sites together with minimal stacking that favors the electron transfer.

  14. Hydrogen generation via photoelectrochemical water splitting using chemically exfoliated MoS2 layers

    International Nuclear Information System (INIS)

    Study on hydrogen generation has been of huge interest due to increasing demand for new energy sources. Photoelectrochemical reaction by catalysts was proposed as a promising technique for hydrogen generation. Herein, we report the hydrogen generation via photoelectrochecmial reaction using films of exfoliated 2-dimensional (2D) MoS2, which acts as an efficient photocatalyst. The film of chemically exfoliated MoS2 layers was employed for water splitting, leading to hydrogen generation. The amount of hydrogen was qualitatively monitored by observing overpressure of a water container. The high photo-current generated by MoS2 film resulted in hydrogen evolution. Our work shows that 2D MoS2 is one of the promising candidates as a photocatalyst for light-induced hydrogen generation. High photoelectrocatalytic efficiency of the 2D MoS2 shows a new way toward hydrogen generation, which is one of the renewable energy sources. The efficient photoelectrocatalytic property of the 2D MoS2 is possibly due to availability of catalytically active edge sites together with minimal stacking that favors the electron transfer

  15. Muon Catalyzed Fusion

    Science.gov (United States)

    Armour, Edward A.G.

    2007-01-01

    Muon catalyzed fusion is a process in which a negatively charged muon combines with two nuclei of isotopes of hydrogen, e.g, a proton and a deuteron or a deuteron and a triton, to form a muonic molecular ion in which the binding is so tight that nuclear fusion occurs. The muon is normally released after fusion has taken place and so can catalyze further fusions. As the muon has a mean lifetime of 2.2 microseconds, this is the maximum period over which a muon can participate in this process. This article gives an outline of the history of muon catalyzed fusion from 1947, when it was first realised that such a process might occur, to the present day. It includes a description of the contribution that Drachrnan has made to the theory of muon catalyzed fusion and the influence this has had on the author's research.

  16. Empirical rate equation model of hydrogen generation for Hanford tank waste

    International Nuclear Information System (INIS)

    Hydrogen is the major flammable gas produced from radioactive tank waste at the Hanford Site. Understanding gas generation and the ability to predict the gas generation rates are important for controlling the flammable gas hazard during interim storage and for planning for future activities such as waste transfer, retrieval, and treatment. Several models have been previously proposed to estimate the hydrogen generation rate but were limited by very little waste data. In this work, based on the availability of a large body of tank waste data, empirical rate equation models are developed and validated to simulate the hydrogen generation from thermal chemical reactions, water and organic radiolysis, and corrosion processes

  17. Continuous hydrogen generation from formic acid; Kontinuierliche Wasserstofferzeugung aus Ameisensaeure

    Energy Technology Data Exchange (ETDEWEB)

    Sponholz, Peter; Mellmann, Doerthe; Boddien, Albert; Gaertner, Felix; Junge, Henrik; Beller, Matthias [Rostock Univ. (Germany). Leibniz-Institut fuer Katalyse e.V.

    2011-07-01

    One of the biggest challenges in this century will be the sustainable supply of energy. A major goal is to meet the energy demand without using fossil fuels and to integrate renewable energy into the energy economy. For applications storage systems for hydrogen are needed. One possible storage system for hydrogen is formic acid which is liquid, non-toxic and has a gravimetric hydrogen content of 4.4%. Our aim is to continuously dehydrogenize formic acid and to use the gas mixture (H{sub 2}, CO{sub 2}) in a connected fuel cell. (orig.)

  18. Steam generators of Phenix: Measurement of the hydrogen concentration in sodium for detecting water leaks in the steam generator tubes

    International Nuclear Information System (INIS)

    The Phenix secondary circuits are provided with measurement systems of hydrogen concentration in sodium, that allow for the detection of possible water leaks in steam generators and the location of a faulty module. A measurement device consists of : a detector with nickel membranes of 0, 3 mm wall thickness, an ion pump with a 200 l/s flow rate, a quadrupole mass spectrometer and a calibrated hydrogen leak. The temperature correction is made automatically. The main tests carried out on the leak detection systems are reported. Since the first system operation (October 24, 1973), the measurements allowed us to obtain the hydrogen diffusion rates through the steam generator tube walls. (author)

  19. Hydrogen generation systems utilizing sodium silicide and sodium silica gel materials

    Science.gov (United States)

    Wallace, Andrew P.; Melack, John M.; Lefenfeld, Michael

    2015-07-14

    Systems, devices, and methods combine reactant materials and aqueous solutions to generate hydrogen. The reactant materials can sodium silicide or sodium silica gel. The hydrogen generation devices are used in fuels cells and other industrial applications. One system combines cooling, pumping, water storage, and other devices to sense and control reactions between reactant materials and aqueous solutions to generate hydrogen. Multiple inlets of varied placement geometries deliver aqueous solution to the reaction. The reactant materials and aqueous solution are churned to control the state of the reaction. The aqueous solution can be recycled and returned to the reaction. One system operates over a range of temperatures and pressures and includes a hydrogen separator, a heat removal mechanism, and state of reaction control devices. The systems, devices, and methods of generating hydrogen provide thermally stable solids, near-instant reaction with the aqueous solutions, and a non-toxic liquid by-product.

  20. Hydrogen Generator by Methane Pyrolysis with Carbon Capture Project

    Data.gov (United States)

    National Aeronautics and Space Administration — ORBITEC proposes to develop, fabricate, and test a system to provide 99.999% hydrogen by efficiently performing methane pyrolysis. The system has three unique...

  1. Selective electrochemical generation of hydrogen peroxide from water oxidation

    CERN Document Server

    Viswanathan, Venkatasubramanian; Nørskov, Jens K

    2015-01-01

    Water is a life-giving source, fundamental to human existence, yet, over a billion people lack access to clean drinking water. Present techniques for water treatment such as piped, treated water rely on time and resource intensive centralized solutions. In this work, we propose a decentralized device concept that can utilize sunlight to split water into hydrogen and hydrogen peroxide. The hydrogen peroxide can oxidize organics while the hydrogen bubbles out. In enabling this device, we require an electrocatalyst that can oxidize water while suppressing the thermodynamically favored oxygen evolution and form hydrogen peroxide. Using density functional theory calculations, we show that the free energy of adsorbed OH$^*$ can be used as a descriptor to screen for selectivity trends between the 2e$^-$ water oxidation to H$_2$O$_2$ and the 4e$^-$ oxidation to O$_2$. We show that materials that bind oxygen intermediates sufficiently weakly, such as SnO$_2$, can activate hydrogen peroxide evolution. We present a rati...

  2. Selective Electrochemical Generation of Hydrogen Peroxide from Water Oxidation.

    Science.gov (United States)

    Viswanathan, Venkatasubramanian; Hansen, Heine A; Nørskov, Jens K

    2015-11-01

    Water is a life-giving source, fundamental to human existence, yet over a billion people lack access to clean drinking water. The present techniques for water treatment such as piped, treated water rely on time and resource intensive centralized solutions. In this work, we propose a decentralized device concept that can utilize sunlight to split water into hydrogen and hydrogen peroxide. The hydrogen peroxide can oxidize organics while the hydrogen bubbles out. In enabling this device, we require an electrocatalyst that can oxidize water while suppressing the thermodynamically favored oxygen evolution and form hydrogen peroxide. Using density functional theory calculations, we show that the free energy of adsorbed OH* can be used to determine selectivity trends between the 2e(-) water oxidation to H2O2 and the 4e(-) oxidation to O2. We show that materials which bind oxygen intermediates sufficiently weakly, such as SnO2, can activate hydrogen peroxide evolution. We present a rational design principle for the selectivity in electrochemical water oxidation and identify new material candidates that could perform H2O2 evolution selectively. PMID:26538037

  3. Baeyer-Villiger oxidation of cyclic ketones with hydrogen peroxide catalyzed by cationic complexes of platinum(II): Selectivity properties and mechanistic studies

    Energy Technology Data Exchange (ETDEWEB)

    Del Todesco Frisone, M.; Pinna, F.; Strukul, G. (Univ. of Venice (Italy))

    1993-01-01

    The catalytic oxidation of simple cyclic ketones with hydrogen peroxide to give the corresponding lactones is reported. The reaction is catalyzed by complexes of Pt(II) of the type [(P-P)Pt(CF[sub 3])(solv)][sup +] (P-P = diphosphine) that may be deactivated by the hydroxy acids formed by hydrolysis of the lactones. The selectivity of the catalyst is studied in the oxidation of substrates like camphor, 2-cyclohexene-1-one, menthone, carvone, and indanones. Cyclobutanone is used to determine the mechanism of the reaction from initial rates studies. The reaction scheme proposed, which accounts for the observed effects of the various reactants, involves the coordination of the ketone on the vacant coordination site of the complex followed by nucleophilic attack of free hydrogen peroxide on the carbonyl carbon. The involvement of a quasi-peroxymetallacyclic intermediate is suggested which rearranges to give the lactone and the starting complex. A comparison with the mechanistic behavior of organic peroxy acids is given. 24 refs., 10 figs., 3 tabs.

  4. PRODUCTION OF COCOA BUTTER-LIKE FATS BY THE LIPASE-CATALYZED INTERESTERIFICATION OF PALM OIL AND HYDROGENATED SOYBEAN OIL

    Science.gov (United States)

    Cocoa butter-like fats were prepared from refined, bleached and deodorized palm oil (RBD-PO) and fully hydrogenated soy oil (HSO) by enzymatic interesterification at various weight ratios of substrates. The cocoa butter-like fats were isolated from the crude interesterification mixture by fractiona...

  5. Cobalt-Embedded Nitrogen-Rich Carbon Nanotubes Efficiently Catalyze Hydrogen Evolution Reaction at All pH Values

    Czech Academy of Sciences Publication Activity Database

    Zou, X.; Huang, X.; Goswami, A.; Silva, R.; Sathe, B. R.; Mikmeková, Eliška; Asefa, T.

    2014-01-01

    Roč. 53, č. 17 (2014), s. 4372-4376. ISSN 1433-7851 R&D Projects: GA MŠk(CZ) LO1212 Institutional support: RVO:68081731 Keywords : carbon nanotubes * cobalt nanoparticles * electrocatalysis * hydrogen evolution reaction * water splitting Subject RIV: JA - Electronics ; Optoelectronics, Electrical Engineering Impact factor: 11.261, year: 2014

  6. Precipitation of UO2 in sodium carbonate solutions by electrolytic hydrogen and catalyzed by Ni-Raney - Bibliography

    International Nuclear Information System (INIS)

    This report proposes abstracts and short versions of a set of documents (studies, patents) dealing with the precipitation of uranium (notably in its oxide form, UO2) in solutions of sodium carbonate. The main objective is to identify the interest of a chemical reduction by electrolytic hydrogen. The author makes a distinction between the most relevant documents and those relatively relevant ones

  7. Effect of water injection on hydrogen generation during severe accident in PWR

    Institute of Scientific and Technical Information of China (English)

    TAO Jun; CAO Xuewu

    2009-01-01

    Effect of water injection on hydrogen generation during severe accident in a 1000 MWe pressurized water reactor was studied.The analyses were carried out with different water injection rates at different core damage stages.The core can be quenched and accident progression can be terminated by water injection at the time before cohesive core debris is formed at lower core region.Hydrogen generation rate decreases with water injection into the core at the peak core temperature of 1700 K,because the core is quenched and reflooded quickly.The water injection at the peak core temperature of 1900 K,the hydrogen generation rate increases at low injection rates of the water,as the core is quenched slowly and the core remains in uncovered condition at high temperatures for a longer time than the situation of high injection rate.At peak core temperature of 2100-2300 K,the Hydrogen generation rate increases by water injection because of the steam serving to the high temperature steam-starved core.Hydrogen generation rate increases significantly after water injection into the core at peak core temperature of 2500 K because of the steam serving to the relocating Zr-U-O mixture.Almost no hydrogen generation can be seen in base case after formation of the molten pool at the lower core region.However,hydrogen is generated if water is injected into the molten pool,because steam serves to the crust supporting the molten pool.Reactor coolant system (RCS) depressurization by opening power operated relief valves has important effect on hydrogen generation.Special attention should be paid to hydrogen generation enhancement caused by RCS depressurization.

  8. In situ generation of hydrogen from water by aluminum corrosion in solutions of sodium aluminate

    OpenAIRE

    Soler Turu, Lluis; Candela Soto, Angélica Maria; Macanás de Benito, Jorge; Muñoz Tapia, Maria; Casado Giménez, Juan

    2009-01-01

    A new process to obtain hydrogen from water using aluminum in sodium aluminate solutions is described and compared with results obtained in aqueous sodium hydroxide. This process consumes only water and aluminum, which are raw materials much cheaper than other compounds used for in situ hydrogen generation, such as hydrocarbons and chemical hydrides, respectively. As a consequence, our process could be an economically feasible alternative for hydrogen to supply fuel cells. Results showed an i...

  9. Hydrogen generation monitoring and mass gain analysis during the steam oxidation for Zircaloy using hydrogen and oxygen sensors

    International Nuclear Information System (INIS)

    The oxidation behavior of Zircaloy-4 at high temperatures in a flowing Ar-H2O (saturated at 323 K) mixed gas was investigated using hydrogen and oxygen sensors installed at a gas outlet, and the utility of the gas sensing methods by using both sensors was examined. The generated amount of hydrogen was determined from the hydrogen partial pressure continuously measured by the hydrogen sensor, and the resultant calculated oxygen amount that reacted with the specimen was in close agreement with the mass gain gravimetrically measured after the experiment. This result demonstrated that the hydrogen partial pressure measurement using a hydrogen sensor is an effective method for examining the steam oxidation of this metal as well as monitoring the hydrogen evolution. The advantage of this method is that the oxidation rate of the metal at any time as a differential quantity is able to be obtained, compared to the oxygen amount gravimetrically measured as an integral quantity. When the temperature was periodically changed in the range of 1173 K to 1523 K, highly accurate measurements could be carried out using this gas monitoring method, although reasonable measurements were not gravimetrically performed due to the fluctuating thermo-buoyancy during the experiment. A change of the oxidation rate was clearly detected at a monoclinic tetragonal transition temperature of ZrO2. From the calculation of the water vapor partial pressure during the thermal equilibrium condition using the hydrogen and oxygen partial pressures, it became clear that a thermal equilibrium state is maintained when the isothermal condition is maintained, but is not when the temperature increases or decreases with time. Based on these results, it was demonstrated that the gas monitoring system using hydrogen and oxygen sensors is very useful for investigating the oxidation process of the Zircaloy in steam. (author)

  10. Hydrogen/syngas generation by simultaneous steam reforming and carbon dioxide absorption

    Energy Technology Data Exchange (ETDEWEB)

    Weimer, T.; Specht, M.; Baumgart, F.; Marquard-Moellenstedt, T.; Sichler, P. [IVE Weimer Process and Energy Technology, Sindelfingen (Germany)

    2002-07-01

    A new process for hydrogen or syngas production from various carbonaceous feedstocks is presented. The main feature of the Absorption Enhanced Reforming (AER-process) is the combination of simultaneous steam reforming, shift reaction and carbon dioxide removal in one reactor. Characterised by high efficiency, low investment cost and a high hydrogen content in the product gas, AER-processes are a promising option for hydrogen generation. Calcinated lime is a suitable carbon dioxide absorbent. In addition to hydrogen supply for electricity generation using PEM-fuel cells, industrial applications are in the refinery sector with a growing hydrogen demand for hydrotreating crude oil and the pulp industry where a lime recycle loop and power generation unit are already installed. 6 refs., 6 figs.

  11. A new approach for hydrogen generation from sewage sludge.

    Science.gov (United States)

    Zhang, Qiwu; Kano, Junya

    2016-02-01

    A new process to produce hydrogen efficiently from sewage sludge (SWS) was developed with co-grinding operation of the dried SWS with calcium and nickel hydroxides (Ca(OH)2 and Ni(OH)2) and subsequent heating of the ground mixture at relatively low temperature below 600°C. A set of analytical methods were used to characterize the ground samples before heating and the gaseous and solid products after heating. Thermo-mass spectroscopic (TG-MS) analysis showed hydrogen occurrence around 450°C. Hydrogen yield over 70g per kg SWS with concentration of 93.6% was obtained with the hydroxide additions of Ca to C from SWS at 1:1 and Ni to C at 1:6, respectively. X-ray diffraction (XRD) analysis of the solid residues after heating confirmed the existences of calcium carbonate and nickel metal. Based on the obtained results, possible reaction pathway was proposed. PMID:26642224

  12. Microsecond X-ray Absorption Spectroscopy Identification of Co(I) Intermediates in Cobaloxime-Catalyzed Hydrogen Evolution.

    Science.gov (United States)

    Smolentsev, Grigory; Cecconi, Bianca; Guda, Alexander; Chavarot-Kerlidou, Murielle; van Bokhoven, Jeroen A; Nachtegaal, Maarten; Artero, Vincent

    2015-10-19

    Rational development of efficient photocatalytic systems for hydrogen production requires understanding the catalytic mechanism and detailed information about the structure of intermediates in the catalytic cycle. We demonstrate how time-resolved X-ray absorption spectroscopy in the microsecond time range can be used to identify such intermediates and to determine their local geometric structure. This method was used to obtain the solution structure of the Co(I) intermediate of cobaloxime, which is a non-noble metal catalyst for solar hydrogen production from water. Distances between cobalt and the nearest ligands including two solvent molecules and displacement of the cobalt atom out of plane formed by the planar ligands have been determined. Combining in situ X-ray absorption and UV/Vis data, we demonstrate how slight modification of the catalyst structure can lead to the formation of a catalytically inactive Co(I) state under similar conditions. Possible deactivation mechanisms are discussed. PMID:26388205

  13. Understanding the Mechanism of the Hydrogen Abstraction from Arachidonic Acid Catalyzed by the Human Enzyme 15-Lipoxygenase-2. A Quantum Mechanics/Molecular Mechanics Free Energy Simulation.

    Science.gov (United States)

    Suardíaz, Reynier; Jambrina, Pablo G; Masgrau, Laura; González-Lafont, Àngels; Rosta, Edina; Lluch, José M

    2016-04-12

    Lipoxygenases (LOXs) are a family of enzymes involved in the biosynthesis of several lipid mediators. In the case of human 15-LOX, the 15-LOX-1 and 15-LOX-2 isoforms show slightly different reaction regiospecificity and substrate specificity, indicating that substrate binding and recognition may be different, a fact that could be related to their different biological role. Here, we have used long molecular dynamics simulations, QM(DFT)/MM potential energy and free energy calculations (using the newly developed DHAM method), to investigate the binding mode of the arachidonic acid (AA) substrate into 15-LOX-2 and the rate-limiting hydrogen-abstraction reaction 15-LOX-2 catalyzes. Our results strongly indicate that hydrogen abstraction from C13 in 15-LOX-2 is only consistent with the "tail-first" orientation of AA, with its carboxylate group interacting with Arg429, and that only the pro-S H13 hydrogen will be abstracted (being the pro-R H13 and H10 too far from the acceptor oxygen atom). At the B3LYP/6-31G(d) level the potential and free energy barriers for the pro-S H13 abstraction of AA by 15-LOX-2 are 18.0 and 18.6 kcal/mol, respectively. To analyze the kinetics of the hydrogen abstraction process, we determined a Markov model corresponding to the unbiased simulations along the state-discretized reaction coordinate. The calculated rates based on the second largest eigenvalue of the Markov matrices agree well with experimental measurements, and also provide the means to directly determine the pre-exponential factor for the reaction by comparing with the free energy barrier height. Our calculated pre-exponential factor is close to the value of kBT/h. On the other hand, our results suggest that the spin inversion of the complete system (including the O2 molecule) that is required to happen at some point along the full process to lead to the final hydroperoxide product, is likely to take place during the hydrogen transfer, which is a proton coupled electron transfer

  14. Tandem hydrogenation and condensation of fluorinated α,β-unsaturated ketones with primary amines, catalyzed by nickel.

    Science.gov (United States)

    Castellanos-Blanco, Nahury; Flores-Alamo, Marcos; García, Juventino J

    2015-09-21

    A simple homogeneous catalytic system based on nickel phosphine complexes has been developed for the transfer hydrogenation and condensation of α,β-unsaturated ketones to yield saturated ones and saturated imines using primary amines as hydrogen donors. Thus, a wide range of fluorinated 1,5-diaryl-1,4-pentadiene-3-ones were allowed to react with substituted benzylamines in the presence of [(dippe)Ni(μ-H)]2 (dippe = 1,2-bis-(diisopropylphosphino)-ethane) using ethanol as a solvent at 180 °C to give the corresponding saturated carbonyl compounds; here hydrogenation of the C[double bond, length as m-dash]C bond was preferred over the C[double bond, length as m-dash]O bond. Under the same reaction conditions but using an excess of benzylamine, a tandem process is then favoured, starting also with the reduction of the C[double bond, length as m-dash]C bond followed by a nucleophilic addition of the primary amine to yield valuable saturated imines with good to excellent yields (62%-91%). PMID:26250992

  15. Electrochemical and photochemical-driven hydrogen evolution catalyzed by a dinuclear CoII-CoII complex

    Science.gov (United States)

    Fu, Ling-Zhi; Zhou, Ling-Ling; Tang, Ling-Zhi; Zhang, Yun-Xiao; Zhan, Shu-Zhong

    2015-04-01

    The reaction of 2,6-diamino-3-[(2-carboxymethyl) phenylazo]-pyridine (L) and CoCl2·6H2O affords a dinuclear cobalt (II) complex [Co2L2Cl3]Cl 1, a molecular catalyst. Electrochemical studies indicate that 1 can electrocatalyze hydrogen evolution both from acetic acid and purely water media (pH 7.0), with a turnover frequency of 40.64 and 750.2 mol of hydrogen per mole of catalyst per hour, respectively. Sustained proton reduction catalysis occurs at glassy carbon (GC) to give H2 over a 48 h electrolysis period with 97% Faradaic yield and no observable decomposition of the catalyst. Photocatalytic experiments indicate that complex 1 in pH 4.0 aqueous solution under air, together with [Ru(bpy)3]Cl2 and ascorbic acid as a sacrificial electron donor, in the presence of blue light (λmax = 469 nm) also can produce hydrogen with a TON = 425 mol of H2 (mol of cat)-1.

  16. Investment in hydrogen tri-generation for wastewater treatment plants under uncertainties

    Science.gov (United States)

    Gharieh, Kaveh; Jafari, Mohsen A.; Guo, Qizhong

    2015-11-01

    In this article, we present a compound real option model for investment in hydrogen tri-generation and onsite hydrogen dispensing systems for a wastewater treatment plant under price and market uncertainties. The ultimate objective is to determine optimal timing and investment thresholds to exercise initial and subsequent options such that the total savings are maximized. Initial option includes investment in a 1.4 (MW) Molten Carbonate Fuel Cell (MCFC) fed by mixture of waste biogas from anaerobic digestion and natural gas, along with auxiliary equipment. Produced hydrogen in MCFC via internal reforming, is recovered from the exhaust gas stream using Pressure Swing Adsorption (PSA) purification technology. Therefore the expansion option includes investment in hydrogen compression, storage and dispensing (CSD) systems which creates additional revenue by selling hydrogen onsite in retail price. This work extends current state of investment modeling within the context of hydrogen tri-generation by considering: (i) Modular investment plan for hydrogen tri-generation and dispensing systems, (ii) Multiple sources of uncertainties along with more realistic probability distributions, (iii) Optimal operation of hydrogen tri-generation is considered, which results in realistic saving estimation.

  17. Ruthenium(0)-catalyzed hydroarylation of alkynes via ketone-directed C-H functionalization using in situ-generated ruthenium complexes.

    Science.gov (United States)

    Hu, Feng; Szostak, Michal

    2016-08-11

    A versatile method for the Ru(0)-catalyzed hydroarylation of alkynes using weakly-coordinating ketones enabled by the in situ generation of a Ru(0) catalyst from an air-stable, inexpensive and user-friendly Ru(ii) precatalyst is reported for the first time. The method provides straightforward access to a wide range of functionalized ketone building blocks that would be difficult to access by conventional methods. Most crucially, this report demonstrates for the first time that the in situ generated Ru(0) catalysts advance the classic Ru(0)-catalyzed C-H functionalization platform to substrates that would otherwise be unreactive. Product manipulation and mechanistic studies are reported. PMID:27411592

  18. Infrared laser induced organic reactions. 2. Laser vs. thermal inducment of unimolecular and hydrogen bromide catalyzed bimolecular dehydration of alcohols

    International Nuclear Information System (INIS)

    It has been demonstrated that a mixture of reactant molecules can be induced by pulsed infrared laser radiation to react via a route which is totally different from the pathway resulting from heating the mixture at 3000C. The high-energy unimolecular elimination of H2O from ethanol in the presence of 2-propanol and HBr can be selectively induced with a pulsed CO2 laser in preference to either a lower energy bimolecular HBr-catalyzed dehydration or the more facile dehydration of 2-propanol. Heating the mixture resulted in the almost exclusive reaction of 2-propanol to produce propylene. It was demonstrated that the bimolecular ethanol + HBr reaction cannot be effectively induced by the infrared laser radiation as evidenced by the detrimental effect on the yield of ethylene as the HBr pressure was increased. The selective, nonthermal inducement of H2O elimination from vibrationally excited ethanol in the presence of 2-propanol required relatively low reactant pressures. At higher pressures intermolecular V--V energy transfer allowed the thermally more facile dehydration from 2-propanol to become the predominant reaction channel

  19. HOGEN{trademark} proton exchange membrane hydrogen generators: Commercialization of PEM electrolyzers

    Energy Technology Data Exchange (ETDEWEB)

    Smith, W.F.; Molter, T.M. [Proton Energy Systems, Inc., Rocky Hill, CT (United States)

    1997-12-31

    PROTON Energy Systems` new HOGEN series hydrogen generators are Proton Exchange Membrane (PEM) based water electrolyzers designed to generate 300 to 1000 Standard Cubic Feet Per Hour (SCFH) of high purity hydrogen at pressures up to 400 psi without the use of mechanical compressors. This paper will describe technology evolution leading to the HOGEN, identify system design performance parameters and describe the physical packaging and interfaces of HOGEN systems. PEM electrolyzers have served US and UK Navy and NASA needs for many years in a variety of diverse programs including oxygen generators for life support applications. In the late 1970`s these systems were advocated for bulk hydrogen generation through a series of DOE sponsored program activities. During the military buildup of the 1980`s commercial deployment of PEM hydrogen generators was de-emphasized as priority was given to new Navy and NASA PEM electrolysis systems. PROTON Energy Systems was founded in 1996 with the primary corporate mission of commercializing PEM hydrogen generators. These systems are specifically designed and priced to meet the needs of commercial markets and produced through manufacturing processes tailored to these applications. The HOGEN series generators are the first step along the path to full commercial deployment of PEM electrolyzer products for both industrial and consumer uses. The 300/1000 series are sized to meet the needs of the industrial gases market today and provide a design base that can transition to serve the needs of a decentralized hydrogen infrastructure tomorrow.

  20. Selective Electrochemical Generation of Hydrogen Peroxide from Water Oxidation

    DEFF Research Database (Denmark)

    Viswanathan, Venkatasubramanian; Hansen, Heine Anton; Nørskov, Jens K.

    2015-01-01

    evolution and form hydrogen peroxide. Using density functional theory calculations, we show that the free energy of adsorbed OH* can be used to determine selectivity trends between the 2e(-) water oxidation to H2O2 and the 4e(-) oxidation to O2. We show that materials which bind oxygen intermediates...

  1. Hydrogen generation from aluminium corrosion in reactor containment spray solutions

    International Nuclear Information System (INIS)

    The aluminium corrosion experiments in reactor containment spray solutions, under the conditions expected to prevail during LOCA in BWR and PWR, were performed in order to investigate relationships between temperature, pH and hydrogen production rates. In order to simulate the conditions in a BWR containment realistic ratios between aluminium surface and water volume and between aluminium surface and oxygen volume were used. Three different aluminium alloys were exposed to spray solutions: AA 1050, AA 5052 and AA 6082. The corrosion rates were measured for BWR solutions (deaerated and aerated) with pH 5 and 9 at 50, 100 and 1500C. The pressure was constantly 0.8 MPa. The hydrogen production rate was measured by means of gas chromatography. In deionized BWR water the corrosion rates did not exceed about 0.05 mm/year in all cases, i.e. were practically independent of temperature and pH. Hydrogen concentrations were less than 0.1 vol.% in cooled dry gas. Corrosion rates and hydrogen production in PWR alkaline solution measured at pH 9.7 and 1500C were very high. AA 5052 alloy was the best material

  2. Combustion of hydrogen-oxygen mixture in electrochemically generated nanobubbles

    NARCIS (Netherlands)

    Svetovoy, Vitaly B.; Sanders, Remco G.P.; Lammerink, Theo S.J.; Elwenspoek, Miko

    2011-01-01

    Ignition of exothermic chemical reactions in small volumes is considered as difficult or impossible due to the large surface-to-volume ratio. Here observation of the spontaneous reaction is reported between hydrogen and oxygen in bubbles whose diameter is smaller than a threshold value around 150 nm

  3. Transition Metal Catalyzed Hydroarylation of Multiple Bonds: Exploration of Second Generation Ruthenium Catalysts and Extension to Copper Systems

    Energy Technology Data Exchange (ETDEWEB)

    T. Brent Gunnoe

    2011-02-17

    , which has provided a comprehensive understanding of the impact of steric and electronic parameters of 'L' on the catalytic hydroarylation of olefins. (3) We have completed and published a detailed mechanistic study of stoichiometric aromatic C-H activation by TpRu(L)(NCMe)Ph (L = CO or PMe{sub 3}). These efforts have probed the impact of functionality para to the site of C-H activation for benzene substrates and have allowed us to develop a detailed model of the transition state for the C-H activation process. These results have led us to conclude that the C-H bond cleavage occurs by a {sigma}-bond metathesis process in which the C-H transfer is best viewed as an intramolecular proton transfer. (4) We have completed studies of Ru complexes possessing the N-heterocyclic carbene IMes (IMes = 1,3-bis-(2,4,6-trimethylphenyl)imidazol-2-ylidene). One of these systems is a unique four-coordinate Ru(II) complex that catalyzes the oxidative hydrophenylation of ethylene (in low yields) to produce styrene and ethane (utilizing ethylene as the hydrogen acceptor) as well as the hydrogenation of olefins, aldehydes and ketones. These results provide a map for the preparation of catalysts that are selective for oxidative olefin hydroarylation. (5) The ability of TpRu(PMe{sub 3})(NCMe)R systems to activate sp{sup 3} C-H bonds has been demonstrated including extension to subsequent C-C bond forming steps. These results open the door to the development of catalysts for the functionalization of more inert C-H bonds. (6) We have discovered that Pt(II) complexes supported by simple nitrogen-based ligands serve as catalysts for the hydroarylation of olefins. Given the extensive studies of Pt-based catalytic C-H activation, we believe these results will provide an entry point into an array of possible catalysts for hydrocarbon functionalization.

  4. DESIGN, SYNTHESIS AND STUDY OF MULTI-COMPONENT AND INTEGRATED SYSTEMS FOR LIGHT-DRIVEN HYDROGEN GENERATION

    Energy Technology Data Exchange (ETDEWEB)

    Professor Richard Eisenberg

    2012-07-18

    The research focussed on fundamental problems in the conversion of light to stored chemical energy. Specifically, work was completed on the design, synthesis and study of multi-component super- and supramolecular systems for photoinduced charge separation, one of the key steps in artificial photosynthesis, and on the use of these and related systems for the photochemical generation of H2 from water. At the center of these systems are chromophores comprised of square planar coordinated Pt(II) ions with arylacetylide and either diimine or terpyridyl ligands. Previous work had shown that the chromophores are photoluminescent in fluid solution with long-lived metal-to-ligand charge transfer (3MLCT) excited states that are necessarily directional. An advance which set the stage for a number of proposed studies was the light-driven production of hydrogen from water using a Pt(terpyridyl)(arylacetylide)+ chromophore and a sacrificial electron donor. The reaction is catalytic and appears to rival previously reported ruthenium bipyridyl systems in terms of H2 production. Variation of system components and mechanistic studies were conducted to understand better the individual steps in the overall process and how to improve its efficiency. Success with light driven H2 generation was employed as a key probe as new systems were constructed consisting of triads for photoinduced charge separation placed in close proximity to the H2 generating catalyst - a Pt colloid - through direct linkage or supramolecular interactions with the polymer used to stabilize the colloid. In order to prepare new donor-chromophore-acceptor (D-C-A) triads and associated D-C and C-A dyads, new ligands were synthesized having functional groups for different coupling reactions such as simple amide formation and Pd-catalyzed coupling. In these systems, the donor was attached to the arylacetylide ligands and the acceptor was linked to the diimine or terpyridyl chelate. Research under the contract proved

  5. Analysis of Hydrogen Generation and Accumulation in U-233 Tube Vaults

    International Nuclear Information System (INIS)

    The purpose of the 233U Safe Storage Program is to enhance the safe storage of 233U-bearing materials. This report describes the work done at the Oak Ridge National Laboratory's Radiochemical Development Facility (RDF) to address questions related to possible hydrogen generation and accumulation in 233U tube vaults. The objective of this effort was to verify assumptions in the mathematical model used to estimate the hydrogen content of the gaseous atmosphere that possibly could occur inside the tube vaults in Building 3019 and to evaluate proposed measures for mitigating any hydrogen concerns. A mathematical model was developed using conservative assumptions to evaluate possible hydrogen generation and accumulation in the tube vaults. The model concluded that an equilibrium concentration would be established below the lower flammability limit (LFL) of 4.1% hydrogen. The major assumptions used in the model that were validated are as follows: (1) The shield plug does not form a seal with the tube vault wall, thus allowing the hydrogen gas to diffuse past the shield plug to the upper section of the tube vault. (2) The tube vault end-cap leaks sufficiently to allow air to be drawn into the tube vault by the off-gas system, thereby purging hydrogen from the upper section of the tube vault. (3) Any hydrogen gas generated completely mixes with the other gases present in the lower section of the tube vault and does not stratify beneath the shield plug. (4) The diffusion coefficient determined from the literature for constant diffusion of hydrogen in air is valid. The coefficient is corrected for temperatures from 0 to 25 C. Another assumption used in the model, that hydrogen generated by radiolytic decomposition of hydrogen-bearing materials (e.g., moisture and plastic) leaks from the cans under steady-state condition, as opposed to a sudden release resulting from rupture of the can(s), was beyond the scope of this investigation. Several parameters from the original model

  6. A composite of borohydride and super absorbent polymer for hydrogen generation

    Science.gov (United States)

    Li, Z. P.; Liu, B. H.; Liu, F. F.; Xu, D.

    To develop a hydrogen source for underwater applications, a composite of sodium borohydride and super absorbent polymer (SAP) is prepared by ball milling sodium borohydride powder with SAP powder, and by dehydrating an alkaline borohydride gel. When sodium polyacrylate (NaPAA) is used as the SAP, the resulting composite exhibits a high rate of borohydride hydrolysis for hydrogen generation. A mechanism of hydrogen evolution from the NaBH 4-NaPAA composite is suggested based on structure analysis by X-ray diffraction and scanning electron microscopy. The effects of water and NiCl 2 content in the precursor solution on the hydrogen evolution behavior are investigated and discussed.

  7. Enantio- and Periselective Nitroalkene Diels-Alder Reactions Catalyzed by Helical-Chiral Hydrogen Bond Donor Catalysts

    Directory of Open Access Journals (Sweden)

    Zhili Peng

    2013-08-01

    Full Text Available Helical-chiral double hydrogen bond donor catalysts promote the nitroalkene Diels-Alder reaction in an enantio- and periselective manner. This represents the first asymmetric catalytic nitroalkene Diels-Alder reaction via LUMO-lowering catalysis. To gain an insight into this new process, the substrate scope of our catalyst was investigated by exploiting readily available 5-substituted pentamethylcyclopentadienes. The catalyst was found to tolerate dienes with different steric demands as well as dienes substituted with heteroatoms. The synthetic utility of 5-substituted pentamethylcyclopentadienes is rather limited, and thus we have developed a three-step route to 1,4,5,5-tetrasubstituted cyclopentadienes from commercially available ketones.

  8. Enantio- and periselective nitroalkene Diels-Alder reactions catalyzed by helical-chiral hydrogen bond donor catalysts.

    Science.gov (United States)

    Peng, Zhili; Narcis, Maurice J; Takenaka, Norito

    2013-01-01

    Helical-chiral double hydrogen bond donor catalysts promote the nitroalkene Diels-Alder reaction in an enantio- and periselective manner. This represents the first asymmetric catalytic nitroalkene Diels-Alder reaction via LUMO-lowering catalysis. To gain an insight into this new process, the substrate scope of our catalyst was investigated by exploiting readily available 5-substituted pentamethylcyclopentadienes. The catalyst was found to tolerate dienes with different steric demands as well as dienes substituted with heteroatoms. The synthetic utility of 5-substituted pentamethylcyclopentadienes is rather limited, and thus we have developed a three-step route to 1,4,5,5-tetrasubstituted cyclopentadienes from commercially available ketones. PMID:23966083

  9. Three-component, one-pot synthesis of benzo[f]indenoquinoline derivatives catalyzed by poly(4-vinylpyridinium) hydrogen sulfate

    Institute of Scientific and Technical Information of China (English)

    Nader Ghaffari Khaligh

    2014-01-01

    7-Aryl-8H-benzo[f]indeno[2,1-b]quinoline-8-one derivatives were synthesized by means of a one-pot condensation of 2-naphthylamine, aromatic aldehydes, and indane-1,3-dione in ethanol under refluxing conditions in the presence of poly(4-vinylpyridinium) hydrogen sulfate, a solid acid catalyst. This method has the advantages of high yield, clean reaction, simple methodology, and short reaction time. The catalyst could be recycled and reused four times without significant loss of activity. The structure of the novel compounds was confirmed by IR, 1H NMR, and 13C NMR spec-troscopy and elemental analysis.

  10. Experimental and modelling evaluation of an ammonia-fuelled microchannel reactor for hydrogen generation / Steven Chiuta

    OpenAIRE

    Chiuta, Steven

    2015-01-01

    In this thesis, ammonia (NH3) decomposition was assessed as a fuel processing technology for producing on-demand hydrogen (H2) for portable and distributed fuel cell applications. This study was motivated by the present lack of infrastructure to generate H2 for proton exchange membrane (PEM) fuel cells. An overview of past and recent worldwide research activities in the development of reactor technologies for portable and distributed hydrogen generation via NH3 decomposition wa...

  11. Solar-Hydrogen-Fuel Cell Prototype as a Source of Renewable Energy Generation

    OpenAIRE

    Andrés Rodríguez-Castellanos; Ernesto López-Torres; Omar Solorza-Feria

    2007-01-01

    A small renewable energy prototype is presented, integrated by a solar photovoltaic module used for electrolysis of water where the resulting hydrogen was fed to a regenerative fuel cell for a clean electricity generation. A photovoltaic module provided DC power to an electrolyzer, to produce 56 cm3/min of hydrogen which is fed to a fuel cell and generate electricity. This prototype was designed and manufactured to show the future energy scenario of renewable energy. For water electrolysis, p...

  12. Continuous/Batch Mg/MgH2/H2O-Based Hydrogen Generator

    Science.gov (United States)

    Kindler, Andrew; Huang, Yuhong

    2010-01-01

    A proposed apparatus for generating hydrogen by means of chemical reactions of magnesium and magnesium hydride with steam would exploit the same basic principles as those discussed in the immediately preceding article, but would be designed to implement a hybrid continuous/batch mode of operation. The design concept would simplify the problem of optimizing thermal management and would help to minimize the size and weight necessary for generating a given amount of hydrogen.

  13. Methane decomposition under a corona discharge to generate COx-free hydrogen

    International Nuclear Information System (INIS)

    A non-thermal plasma reforming unit operating at atmospheric pressure has been developed for converting methane to COx-free hydrogen. Argon was used to provide additional electrons and photons for higher reaction rates. A series of experiments was performed for positive corona discharge at a fixed inter-electrode distance (15 mm) to study the effects of discharge power (range of 14–20 W) and residence time (60, 120, 180 and 240 s). A second series of experiments studied the effect of inter-electrode distance on hydrogen production, with distances of 15, 20, 25, 30 and 35 mm tested. The analysis of the results shows that both discharge power and residence time, have a positive influence on methane conversion, hydrogen selectivity and energy conversion efficiency. Longer discharge gaps favour hydrogen production. A final series of experiments on corona polarity showed that a positive discharge was preferable. - Highlights: • We examine plasma-assisted COx-free hydrogen generation from methane. • Higher powers and residence times favour hydrogen production. • Positive polarity and higher inter-electrode distances favour hydrogen production. • Energy conversion efficiency is mainly governed by hydrogen selectivity. • Corona discharges are a promising approach for hydrogen generation from methane

  14. Electrolysis of ammonia for hydrogen production catalyzed by Pt and Pt-Ir deposited on nickel foam

    Institute of Scientific and Technical Information of China (English)

    Min; Jiang; Dandan; Zhu; Xuebo; Zhao

    2014-01-01

    Electrolysis of ammonia in alkaline electrolyte solution was applied for the production of hydrogen. Both Pt-loaded Ni foam and Pt-Ir loaded Ni foam electrodes were prepared by electrodeposition and served as anode and cathode in ammonia electrolytic cell, respectively. The electrochemical behaviors of ammonia in KOH solution were individually investigated via cyclic voltammetry on three electrodes, i.e. bare Ni foam electrode, Pt-loaded Ni foam electrode and Pt-Ir loaded Ni foam electrode. The morphology and composition of the prepared Ni foam electrode were analyzed by scanning electron microscopy(SEM) and X-ray diffraction(XRD). Effects of the concentration of electrolyte solution and temperature of electrolytic cell on the electrolysis reaction were examined in order to enhance the efficiency of ammonia electrolysis. The competition of ammonia electrolysis and water electrolysis in the same alkaline solution was firstly proposed to explain the changes of cell voltage with the electrolysis proceeding. At varying current densities, different cell voltages could be obtained from galvanostatic curves.The low cell voltage of 0.58 V, which is less than the practical electrolysis voltage of water(1.6 V), can be obtained at a current density of2.5 mA/cm2. Based on some experimental parameters, such as the applied current, the resulting cell voltage and output of hydrogen gas, the power consumption per gram of H2produced can be estimated.

  15. Integrated photoelectrochemical energy storage: solar hydrogen generation and supercapacitor

    OpenAIRE

    Xinhui Xia; Jingshan Luo; Zhiyuan Zeng; Cao Guan; Yongqi Zhang; Jiangping Tu; Hua Zhang; Hong Jin Fan

    2012-01-01

    Current solar energy harvest and storage are so far realized by independent technologies (such as solar cell and batteries), by which only a fraction of solar energy is utilized. It is highly desirable to improve the utilization efficiency of solar energy. Here, we construct an integrated photoelectrochemical device with simultaneous supercapacitor and hydrogen evolution functions based on TiO2/transition metal hydroxides/oxides core/shell nanorod arrays. The feasibility of solar-driven pseud...

  16. Hydrogen generation through massive corrosion of deformed aluminum in water

    Energy Technology Data Exchange (ETDEWEB)

    Czech, E.; Troczynski, T. [Materials Engineering Department, University of British Columbia, 309-6350 Stores Rd., Vancouver, BC V6T 1Z4 (Canada)

    2010-02-15

    Aluminum, one of most reactive metals, rapidly corrodes in strong acidic or alkaline solutions but passivates at pH of about 5-9. We have determined that the passivation of aluminum in this range of pH, and in particular in regular tap water, can be substantially prevented after milling of aluminum with water-soluble inorganic salts (referred to as ''WIS''), such as KCl or NaCl. Ensuing corrosion of Al in tap water, with accompanying release of hydrogen and precipitation of aluminum hydroxide, at normal pressure and moderate temperatures ({proportional_to}55 C) is rapid and substantial. For example, {proportional_to}92% of the Al in the Al-WIS system when milled for 1 h and {proportional_to}81% when milled for 15 min, corrodes in 1 h, with the release of 1.5 mol of hydrogen per each mole of Al consumed in the reaction. Besides gaseous hydrogen, only solid aluminum hydroxides were formed as the reaction byproducts, opening up the possibility of straightforward recycling of the system. The effects of WIS concentration, chemistry of other additives, powder particle size, temperature, and milling conditions on the reaction kinetics are reported. (author)

  17. Preparation and immobilization of diNOsarcobalt(III complex in zeolite y for the catalyzed production of hydrogen peroxide

    Directory of Open Access Journals (Sweden)

    José G. Carriazo

    2013-01-01

    Full Text Available A complex cation, diNOsarcobalt(III, [Co(diNOsar]3+, (diNOsar = 1,8-dinitro-3,6,10,13,16,19-hexaazabicyclo-[6.6.6]eicosane, was synthesized and immobilized in the cavities of a Y zeolite by the reaction of precursor species in the pores of the zeolite. The encapsulated material was compared to the compound diNOsarcobalt(III chloride, [Co(diNOsar]Cl3. Both diNOsarcobalt(III chloride and the zeolite-encapsulated complex, [Co(diNOsar]3+/zeolite, were obtained in high yield and characterized by ultraviolet-visible and infrared spectroscopy. X-ray diffraction demonstrated the incorporation of the complex cation into the pores of the zeolite. The catalytic production of hydrogen peroxide from oxygenated water confirmed the successful synthesis of the complex diNOsarcobalt(III immobilized in the zeolite.

  18. Efficient transfer hydrogenation reaction Catalyzed by a dearomatized PN 3P ruthenium pincer complex under base-free Conditions

    KAUST Repository

    He, Lipeng

    2012-03-01

    A dearomatized complex [RuH(PN 3P)(CO)] (PN 3PN, N′-bis(di-tert-butylphosphino)-2,6-diaminopyridine) (3) was prepared by reaction of the aromatic complex [RuH(Cl)(PN 3P)(CO)] (2) with t-BuOK in THF. Further treatment of 3 with formic acid led to the formation of a rearomatized complex (4). These new complexes were fully characterized and the molecular structure of complex 4 was further confirmed by X-ray crystallography. In complex 4, a distorted square-pyramidal geometry around the ruthenium center was observed, with the CO ligand trans to the pyridinic nitrogen atom and the hydride located in the apical position. The dearomatized complex 3 displays efficient catalytic activity for hydrogen transfer of ketones in isopropanol. © 2011 Elsevier B.V. All rights reserved.

  19. Hydrogen generation systems and methods utilizing sodium silicide and sodium silica gel materials

    Science.gov (United States)

    Wallace, Andrew P.; Melack, John M.; Lefenfeld, Michael

    2015-08-11

    Systems, devices, and methods combine thermally stable reactant materials and aqueous solutions to generate hydrogen and a non-toxic liquid by-product. The reactant materials can sodium silicide or sodium silica gel. The hydrogen generation devices are used in fuels cells and other industrial applications. One system combines cooling, pumping, water storage, and other devices to sense and control reactions between reactant materials and aqueous solutions to generate hydrogen. Springs and other pressurization mechanisms pressurize and deliver an aqueous solution to the reaction. A check valve and other pressure regulation mechanisms regulate the pressure of the aqueous solution delivered to the reactant fuel material in the reactor based upon characteristics of the pressurization mechanisms and can regulate the pressure of the delivered aqueous solution as a steady decay associated with the pressurization force. The pressure regulation mechanism can also prevent hydrogen gas from deflecting the pressure regulation mechanism.

  20. Hydrogenation vs. H-D isotope scrambling during the conversion of ethylene with hydrogen/deuterium catalyzed by platinum under single-collision conditions.

    Science.gov (United States)

    Dong, Yujung; Ebrahimi, Maryam; Tillekaratne, Aashani; Simonovis, Juan Pablo; Zaera, Francisco

    2016-07-28

    The catalytic hydrogenation of olefins promoted by transition metals, represented here by the conversion of ethylene with platinum, was studied under a unique regime representing pressures in the mTorr range and single-collision conditions. Isotope labeling was used to follow the concurrent H-D exchange steps that occur during this conversion. Multiple isotope substitutions were observed in the resulting ethane products, reflecting the operability of the reversible stepwise mechanism proposed a long time ago by Horiuti and Polanyi. In fact, the ethane isotopologue distributions obtained in these experiments reflect a much higher probability for the dehydrogenation of ethyl intermediates back to the olefin, relative to the hydrogenation to ethane, than typically seen in this catalysis. In addition, a second mechanistic pathway was clearly identified, responsible for most of the dideuteroethane produced. Based on the dependence of the rates of formation of each isotopologue on the fluxes of deuterium and ethylene, it is argued that this second route may be a "reverse" Eley-Rideal step between gas-phase ethylene and two deuterium atoms adsorbed on adjacent sites of the platinum surface. The clear identification of this second pathway is new, and was possible thanks to our ability to explore a new single-collision intermediate pressure regime. PMID:27373226

  1. Development of generator-cooling hydrogen purity improvement system using hydrogen absorbing alloy; Suiso kyuzo gokin ni yoru hatsudenkinai suiso jundo kojo system no kaihatsu

    Energy Technology Data Exchange (ETDEWEB)

    Nishimura, Y.; Sato, J.; Haruki, N.; Kogi, T.; Okuno, Y. [The Kansai Electric Power Co. Inc., Osaka (Japan); Takeda, H.; Wakisaka, Y. [The Japan Steel Works, Ltd., Tokyo (Japan); Fujita, T. [Mitsubishi Electric Corp., Tokyo (Japan)

    1997-01-31

    A generator-cooling hydrogen purity improvement system was developed by utilizing hydrogen absorbing and discharging functions of hydrogen storage alloy. For demonstration test with an actual machine, four elements, Ca, Ni, Mm and Al, were used as hydrogen storage alloys. To treat hydrogen gas with a wide range of purity and reduce hydrogen gas feed, flow operation for hydrogen purity improvement, batch operation, and recycle operation for maintaining the hydrogen purity were performed. As a result of the generator-cooling hydrogen purity improvement demonstration test, it was found that the hydrogen purity can be enhanced from 97.69% before operation to 99.9% after operation for 104 hours and to 99.95% after operation for 140 hours. The hydrogen recovery rates during flow test and batch test were between 92 and 95%. For the hydrogen purity maintaining test, it was confirmed that the high hydrogen purity of 99.9% has been continuously maintained for 140 days, and that the hydrogen recovery rate was over 99%. 2 refs., 15 figs., 3 tabs.

  2. Study on hydrogen peroxide generation by water surface discharge

    Czech Academy of Sciences Publication Activity Database

    Yoshihara, K.; Ruma, Ruma.; Aoki, N.; Hosseini, S.H.R.; Sakugawa, T.; Akiyama, H.; Lukeš, Petr

    San Francisco : IEEE, 2013, s. 1-5. ISBN 978-1-4673-5167-6. - (IEEE. 101034). [IEEE Pulsed Power & Plasma Science Conference – PPPS 2013/19./. San Francisco (US), 16.07.2013-21.07.2013] Grant ostatní: Rada Programu interní podpory projektů mezinárodní spolupráce AV ČR(CZ) M100431203 Institutional support: RVO:61389021 Keywords : underwater discharge * water surface discharge * hydrogen peroxide Subject RIV: BL - Plasma and Gas Discharge Physics http://dx.doi.org/10.1109/PPC.2013.6627582

  3. Defects generation by hydrogen passivation of polycrystalline silicon thin films

    Czech Academy of Sciences Publication Activity Database

    Honda, Shinya; Mates, Tomáš; Ledinský, Martin; Fejfar, Antonín; Kočka, Jan; Yamazaki, T.; Uraoka, Y.; Fuyuki, T.; Boldyryeva, Hanna; Macková, Anna; Peřina, Vratislav

    2006-01-01

    Roč. 80, - (2006), s. 653-657. ISSN 0038-092X R&D Projects: GA MŽP(CZ) SM/300/1/03; GA MŽP(CZ) SN/3/172/05; GA AV ČR IAA1010413; GA ČR(CZ) GD202/05/H003; GA AV ČR IAA1010316 Institutional research plan: CEZ:AV0Z10100521; CEZ:AV0Z10480505 Keywords : hydrogen passivation * ERDA * photoluminescence * Raman spectroscopy * Si-H 2 bonding * H 2 molecules * grain size. Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 1.431, year: 2006

  4. Solid-state-reaction synthesis of cotton-like CoB alloy at room temperature as a catalyst for hydrogen generation.

    Science.gov (United States)

    Wang, Xingpu; Liao, Jinyun; Li, Hao; Wang, Hui; Wang, Rongfang

    2016-08-01

    A novel room-temperature solid-state reaction is developed to synthesize cotton-like CoB alloy (CoBSSR) catalysts with a large specific surface area of 222.4m(2)g(-1). In the hydrolysis of ammonia borane catalyzed by the CoBSSR, the rate of hydrogen generation can reach 68.7mLmin(-1) with a turnover frequency (TOF) value of ca. 6.9Lhydrogenmin(-1)gcatalyst(-1) at 25°C. The TOF value is about 2 times as large as that of CoB alloy prepared by a regular solid-state reaction, which is also much higher than those of the CoB catalysts recently reported in the literature. The activation energy of the hydrolysis of ammonia borane catalyzed by the CoBSSR is as low as 22.78kJmol(-1), hinting that the CoBSSR possesses high catalytic activity, which may be attributed to the large specific surface area and the abundant porous structure. The high catalytic performance, good recoverability and low cost of the CoBSSR enable it to be a promissing catalyst condidate in the hydrolysis of ammonia borane for hydrogen production in commercial application. PMID:27163841

  5. Zircaloy-oxidation and hydrogen-generation rates in degraded-core accident situations

    International Nuclear Information System (INIS)

    Oxidation of Zircaloy cladding is the primary source of hydrogen generated during a degraded-core accident. In this paper, reported Zircaloy oxidation rates, either measured at 1500 to 18500C or extrapolated from the low-temperature data obtained at 0C, are critically reviewed with respect to their applicability to a degraded-core accident situation in which the high-temperature fuel cladding is likely to be exposed to and oxidized in mixtures of hydrogen and depleted steam, rather than in an unlimited flux of pure steam. New results of Zircaloy oxidation measurements in various mixtures of hydrogen and steam are reported for >15000C. The results show significantly smaller oxidation and, hence, hydrogen-generation rates in the mixture, compared with those obtained in pure steam. It is also shown that a significant fraction of hydrogen, generated as a result of Zircaloy oxidation, is dissolved in the cladding material itself, which prevents that portion of hydrogen from reaching the containment building space. Implications of these findings are discussed in relation to a more realistic method of quantifying the hydrogen source term for a degraded-core accident analysis

  6. Research on hydrogen ion nano-beam generation

    International Nuclear Information System (INIS)

    Our objective is to develop high-resolution nano-meter-size hydrogen beams using duo-plasmatron type ion sources and the static focusing lens system. After modification and optimization of the ion source and focusing electrode configurations, the beam divergence angle of the order of 10-3 rad is achieved in hydrogen beams. In addition, optimizations were made in the beam size measurement system. We realized the measurement accuracies less than 10 nano-meter in position and the pico-ampere order in the beam current. The beam parameters are obtained as a function of the extraction voltage and compared with the calculated values. The result of beam width measurement shows 0.16 μm at the acceleration voltage of 46 kV. This size of beam is useful for detailed nondestructive study on the inside structure of the materials such as semiconductor devices. The μm light ion beam is to be useful to investigate trace elements in cell metabolism. (Y. Tanaka)

  7. Control of microbially generated hydrogen sulfide in produced waters

    Energy Technology Data Exchange (ETDEWEB)

    Burger, E.D.; Vance, I.; Gammack, G.F.; Duncan, S.E.

    1995-12-31

    Production of hydrogen sulfide in produced waters due to the activity of sulfate-reducing bacteria (SRB) is a potentially serious problem. The hydrogen sulfide is not only a safety and environmental concern, it also contributes to corrosion, solids formation, a reduction in produced oil and gas values, and limitations on water discharge. Waters produced from seawater-flooded reservoirs typically contain all of the nutrients required to support SRB metabolism. Surface processing facilities provide a favorable environment in which SRB flourish, converting water-borne nutrients into biomass and H{sub 2}S. This paper will present results from a field trial in which a new technology for the biochemical control of SRB metabolism was successfully applied. A slip stream of water downstream of separators on a produced water handling facility was routed through a bioreactor in a side-steam device where microbial growth was allowed to develop fully. This slip stream was then treated with slug doses of two forms of a proprietary, nonbiocidal metabolic modifier. Results indicated that H{sub 2}S production was halted almost immediately and that the residual effect of the treatment lasted for well over one week.

  8. Study of hydrogen consumption reaction catalyzed by Pd ions in the simulated high-level liquid waste

    International Nuclear Information System (INIS)

    To ensure the safety for storage of high-level liquid waste (HLLW) in tanks is one of the most important safety issues in a reprocessing plant since almost all radioactive materials under processing are collected in these tanks. Accordingly the behavior of radiolytically formed hydrogen (H2) in these tanks is one of key issues and has been studied by several researchers because it might cause an explosion. They reported that not all of H2 formed in HLLW comes out in the gas phase because H2 is consumed by some un-clarified secondary reaction which may be caused by the irradiation and/or by the catalytic effect of certain fission product (FP) in HLLW. In order to clarify such effect, we carried out the experiments using the simulated high level liquid waste (SHLLW) with and without palladium (Pd) group ions under irradiation and non-irradiation conditions. As a result, it was found that H2 consumption reaction is not caused by radiation as was understood so far but is caused by a catalytic effect of Pd ion in SHLLW. That is, H2 is reacting with HNO3 and forming H2O and NOx. Using the catalytic reaction rate constant measured in the experiments, the analysis showed that the H2 concentration in the gas phase of an HLLW tank does not reach its explosion limit of 4% even if the sweeping air stops for a long time. (authors)

  9. Reaction Mechanisms of Metals with Hydrogen Sulfide and Thiols in Model Wine. Part 1: Copper-Catalyzed Oxidation.

    Science.gov (United States)

    Kreitman, Gal Y; Danilewicz, John C; Jeffery, David W; Elias, Ryan J

    2016-05-25

    Sulfidic off-odors as a result of hydrogen sulfide (H2S) and low-molecular-weight thiols are commonly encountered in wine production. These odors are usually removed by the process of Cu(II) fining, a process that remains poorly understood. The present study aims to elucidate the underlying mechanisms by which Cu(II) interacts with H2S and thiol compounds (RSH) under wine-like conditions. Copper complex formation was monitored along with H2S, thiol, oxygen, and acetaldehyde concentrations after the addition of Cu(II) (50 or 100 μM) to air-saturated model wine solutions containing H2S, cysteine, 6-sulfanylhexan-1-ol, or 3-sulfanylhexan-1-ol (300 μM each). The presence of H2S and thiols in excess to Cu(II) led to the rapid formation of ∼1.4:1 H2S/Cu and ∼2:1 thiol/Cu complexes, resulting in the oxidation of H2S and thiols and reduction of Cu(II) to Cu(I), which reacted with oxygen. H2S was observed to initially oxidize rather than form insoluble copper sulfide. The proposed reaction mechanisms provide insight into the extent to which H2S can be selectively removed in the presence of thiols in wine. PMID:27133282

  10. Greener Selective Cycloalkane Oxidations with Hydrogen Peroxide Catalyzed by Copper-5-(4-pyridyltetrazolate Metal-Organic Frameworks

    Directory of Open Access Journals (Sweden)

    Luísa Martins

    2015-10-01

    Full Text Available Microwave assisted synthesis of the Cu(I compound [Cu(µ4-4-ptz]n [1, 4-ptz = 5-(4-pyridyltetrazolate] has been performed by employing a relatively easy method and within a shorter period of time compared to its sister compounds. The syntheses of the Cu(II compounds [Cu3(µ3-4-ptz4(µ2-N32(DMF2]n∙(DMF2n (2 and [Cu(µ2-4-ptz2(H2O2]n (3 using a similar method were reported previously by us. MOFs 1-3 revealed high catalytic activity toward oxidation of cyclic alkanes (cyclopentane, -hexane and -octane with aqueous hydrogen peroxide, under very mild conditions (at room temperature, without any added solvent or additive. The most efficient system (2/H2O2 showed, for the oxidation of cyclohexane, a turnover number (TON of 396 (TOF of 40 h−1, with an overall product yield (cyclohexanol and cyclohexanone of 40% relative to the substrate. Moreover, the heterogeneous catalytic systems 1–3 allowed an easy catalyst recovery and reuse, at least for four consecutive cycles, maintaining ca. 90% of the initial high activity and concomitant high selectivity.

  11. Empirical rate equation model and rate calculations of hydrogen generation for Hanford tank waste; FINAL

    International Nuclear Information System (INIS)

    Empirical rate equations are derived to estimate hydrogen generation based on chemical reactions, radiolysis of water and organic compounds, and corrosion processes. A comparison of the generation rates observed in the field with the rates calculated for twenty eight tanks shows agreement with in a factor of two to three

  12. Empirical rate equation model and rate calculations of hydrogen generation for Hanford tank waste

    International Nuclear Information System (INIS)

    Empirical rate equations are derived to estimate hydrogen generation based on chemical reactions, radiolysis of water and organic compounds, and corrosion processes. A comparison of the generation rates observed in the field with the rates calculated for twenty eight tanks shows agreement within a factor of two to three

  13. Photochemical hydrogen production from water catalyzed by CdTe quantum dots/molecular cobalt catalyst hybrid systems.

    Science.gov (United States)

    Han, Kai; Wang, Mei; Zhang, Shuai; Wu, Suli; Yang, Yong; Sun, Licheng

    2015-04-25

    A hybrid system with a coordinative interaction between a cobalt complex of a N2S2-tetradentate ligand and CdTe quantum dots displayed a high activity (initial TOF 850 h(-1)) and improved stability (TON 1.44 × 10(4) based on catalyst over 30 h) for the photochemical H2 generation from water, with a quantum efficiency of 5.32% at 400 nm. PMID:25800286

  14. Hydrogen generation by nuclear power for sustainable development in the 21-st century

    International Nuclear Information System (INIS)

    Hydrogen is the main non-polluting fuel. It is produced by natural gas steam reforming, water electrolysis and thermonuclear processes. Currently, 4% of the hydrogen world production is obtained by water electrolysis. The use of nuclear power for hydrogen production avoids the generation of greenhouse gases and the dependence of primary external energy sources. The US is currently developing a modular reactor for hydrogen production and water desalination, STAR - H2 (Secure Transportable Autonomous Reactor for Hydrogen production) with fast neutrons, lead cooling and passive safety systems operating at a temperature of 780 deg C. Also, a Russian reactor of the same type is operated at 540 deg C. China and India joint industrial countries like France, Japan, Russia and US in recognizing that any strategies aiming at a future with clean energy implies the nuclear energy

  15. Hydrogen generation from steam reforming of ethanol in dielectric barrier discharge

    Institute of Scientific and Technical Information of China (English)

    Baowei Wang; Yijun Lü; Xu Zhang; Shuanghui Hu

    2011-01-01

    Dielectric barrier discharge(DBD)was used for the generation of hydrogen from ethanol reforming.Effects of reaction conditions,such as vaporization temperature,ethanol flow rate,water/ethanol ratio,and addition of oxygen,on the ethanol conversion and hydrogen yield,were studied.The results showed that the increase of ethanol flow rate decreased ethanol conversion and hydrogen yield,and high water/ethanol ratio and addition of oxygen were advantageous.Ethanol conversion and hydrogen yield increased with the vaporization room temperature up to the maximum at first,and then decreased slightly.The maximum hydrogen yield of 31.8% was obtained at an ethanol conversion of 88.4% under the optimum operation conditions of vaporization room temperature of 120℃,ethanol flux of 0.18 mL/min,water/ethanol ratio of 7.7 and oxygen volume concentration of 13.3%.

  16. Selective hydrogenation of 2-methyl-3-butyn-2-ol catalyzed by embedded polymer-protected PdZn nanoparticles

    Energy Technology Data Exchange (ETDEWEB)

    Okhlopkova, Lyudmila B., E-mail: mila65@catalysis.ru; Matus, Ekaterina V.; Prosvirin, Igor P.; Kerzhentsev, Michail A.; Ismagilov, Zinfer R. [Boreskov Institute of Catalysis (Russian Federation)

    2015-12-15

    PdZn/TiO{sub 2} catalysts were synthesized by sol–gel method using a template Pluronic F127. PdZn nanoparticles with the size ranging from 1.7 to 2 nm were prepared by ethylene glycol reduction of ZnCl{sub 2} and Pd(CH{sub 3}COO){sub 2} in the presence of stabilizer and introduced into the matrix by addition into TiO{sub 2} sol, followed by different activation procedures. The structure, particles size, and chemical composition of nanoparticles and catalysts were characterized by transmission electron microscopy, X-ray photoelectron spectroscopy, X-ray fluorescence spectroscopy, and energy dispersive spectroscopy. The prepared catalysts have been tested in the selective hydrogenation of 2-methyl-3-butyn-2-ol, and the results have been compared with catalysts prepared by conventional impregnation. The results indicate that bimetallic PdZn nanoparticles-based catalysts show higher selectivity than corresponding monometallic Pd/TiO{sub 2}. Embedded on titania, bimetallic nanoparticles stabilized with polyvinylpyrrolidone exhibit good activity (1.1–1.8 mol MBY/mol Pd/s{sup −1}) and high selectivity to 2-methyl-3-buten-2-ol (81.5–88.9 % at 95 % conversion). The influence of the nature of the stabilizer, the stabilizer/metal molar ratio, and activation conditions on the catalytic behavior of the samples was analyzed. It is shown that the particle size does not significantly affect the catalytic properties in the range of 4.4–6.5 nm. The nature and amount of stabilizer seem to be crucial to prepare efficient catalyst.

  17. InP nanopore arrays for photoelectrochemical hydrogen generation

    Science.gov (United States)

    Li, Qiang; Zheng, Maojun; Zhang, Bin; Zhu, Changqing; Wang, Faze; Song, Jingnan; Zhong, Miao; Ma, Li; Shen, Wenzhong

    2016-02-01

    We report a facile and large-scale fabrication of highly ordered one-dimensional (1D) indium phosphide (InP) nanopore arrays (NPs) and their application as photoelectrodes for photoelectrochemical (PEC) hydrogen production. These InP NPs exhibit superior PEC performance due to their excellent light-trapping characteristics, high-quality 1D conducting channels and large surface areas. The photocurrent density of optimized InP NPs is 8.9 times higher than that of planar counterpart at an applied potential of +0.3 V versus RHE under AM 1.5G illumination (100 mW cm-2). In addition, the onset potential of InP NPs exhibits 105 mV of cathodic shift relative to planar control. The superior performance of the nanoporous samples is further explained by Mott-Schottky and electrochemical impedance spectroscopy ananlysis.

  18. Enzymatic generation of hydrogen peroxide shows promising antifouling effect

    DEFF Research Database (Denmark)

    Kristensen, J.B.; Olsen, Stefan Møller; Laursen, B.S.; Kragh, K.M.; Poulsen, C.H.; Besenbacher, F.; Meyer, R.L.

    2010-01-01

    The antifouling (AF) potential of hydrogen peroxide (H2O2) produced enzymatically in a coating containing starch, glucoamylase, and hexose oxidase was evaluated in a series of laboratory tests and in-sea field trials. Dissolved H2O2 inhibited bacterial biofilm formation by eight of nine marine...... Proteobacteria, tested in microtiter plates. However, enzymatically produced H2O2 released from a coating did not impede biofilm formation by bacteria in natural seawater tested in a biofilm reactor. A field trial revealed a noticeable effect of the enzyme system: after immersion in the North Sea for 97 days......, the reference coating without enzymes had 35-40 barnacles, 10% area coverage by diatoms and 15% area coverage by tunicates. The enzyme containing coating had only 6-12 barnacles, 10% area coverage by diatoms and no tunicates. The enzyme system had a performance similar to a copper-based commercial...

  19. CHALLENGES IN GENERATING HYDROGEN BY HIGH TEMPERATURE ELECTROLYSIS USING SOLID OXIDE CELLS

    Energy Technology Data Exchange (ETDEWEB)

    M. S. Sohal; J. E. O' Brien; C. M. Stoots; M. G. McKellar; J. S. Herring; E. A. Harvego

    2008-03-01

    Idaho National Laboratory’s (INL) high temperature electrolysis research to generate hydrogen using solid oxide electrolysis cells is presented in this paper. The research results reported here have been obtained in a laboratory-scale apparatus. These results and common scale-up issues also indicate that for the technology to be successful in a large industrial setting, several technical, economical, and manufacturing issues have to be resolved. Some of the issues related to solid oxide cells are stack design and performance optimization, identification and evaluation of cell performance degradation parameters and processes, integrity and reliability of the solid oxide electrolysis (SOEC) stacks, life-time prediction and extension of the SOEC stack, and cost reduction and economic manufacturing of the SOEC stacks. Besides the solid oxide cells, balance of the hydrogen generating plant also needs significant development. These issues are process and ohmic heat source needed for maintaining the reaction temperature (~830°C), high temperature heat exchangers and recuperators, equal distribution of the reactants into each cell, system analysis of hydrogen and associated energy generating plant, and cost optimization. An economic analysis of this plant was performed using the standardized H2A Analysis Methodology developed by the Department of Energy (DOE) Hydrogen Program, and using realistic financial and cost estimating assumptions. The results of the economic analysis demonstrated that the HTE hydrogen production plant driven by a high-temperature helium-cooled nuclear power plant can deliver hydrogen at a cost of $3.23/kg of hydrogen assuming an internal rate of return of 10%. These issues need interdisciplinary research effort of federal laboratories, solid oxide cell manufacturers, hydrogen consumers, and other such stakeholders. This paper discusses research and development accomplished by INL on such issues and highlights associated challenges that need to

  20. Efficiency and economics of large scale hydrogen liquefaction. [for future generation aircraft requirements

    Science.gov (United States)

    Baker, C. R.

    1975-01-01

    Liquid hydrogen is being considered as a substitute for conventional hydrocarbon-based fuels for future generations of commercial jet aircraft. Its acceptance will depend, in part, upon the technology and cost of liquefaction. The process and economic requirements for providing a sufficient quantity of liquid hydrogen to service a major airport are described. The design is supported by thermodynamic studies which determine the effect of process arrangement and operating parameters on the process efficiency and work of liquefaction.

  1. Identification of intrinsic catalytic activity for electrochemical reduction of water molecules to generate hydrogen

    KAUST Repository

    Shinagawa, Tatsuya

    2015-01-01

    Insufficient hydronium ion activities at near-neutral pH and under unbuffered conditions induce diffusion-limited currents for hydrogen evolution, followed by a reaction with water molecules to generate hydrogen at elevated potentials. The observed constant current behaviors at near neutral pH reflect the intrinsic electrocatalytic reactivity of the metal electrodes for water reduction. This journal is © the Owner Societies.

  2. Hydrogen Fuel Cell Analysis: Lessons Learned from Stationary Power Generation Final Report

    Energy Technology Data Exchange (ETDEWEB)

    Scott E. Grasman; John W. Sheffield; Fatih Dogan; Sunggyu Lee; Umit O. Koylu; Angie Rolufs

    2010-04-30

    This study considered opportunities for hydrogen in stationary applications in order to make recommendations related to RD&D strategies that incorporate lessons learned and best practices from relevant national and international stationary power efforts, as well as cost and environmental modeling of pathways. The study analyzed the different strategies utilized in power generation systems and identified the different challenges and opportunities for producing and using hydrogen as an energy carrier. Specific objectives included both a synopsis/critical analysis of lessons learned from previous stationary power programs and recommendations for a strategy for hydrogen infrastructure deployment. This strategy incorporates all hydrogen pathways and a combination of distributed power generating stations, and provides an overview of stationary power markets, benefits of hydrogen-based stationary power systems, and competitive and technological challenges. The motivation for this project was to identify the lessons learned from prior stationary power programs, including the most significant obstacles, how these obstacles have been approached, outcomes of the programs, and how this information can be used by the Hydrogen, Fuel Cells & Infrastructure Technologies Program to meet program objectives primarily related to hydrogen pathway technologies (production, storage, and delivery) and implementation of fuel cell technologies for distributed stationary power. In addition, the lessons learned address environmental and safety concerns, including codes and standards, and education of key stakeholders.

  3. Lessons learned from hydrogen generation and burning during the TMI-2 event

    International Nuclear Information System (INIS)

    This document summarizes what has been learned from generation of hydrogen in the reactor core and the hydrogen burn that occurred in the containment building of the Three Mile Island Unit No. 2 (TMI-2) nuclear power plant on March 28, 1979. During the TMI-2 loss-of-coolant accident (LOCA), a large quantity of hydrogen was generated by a zirconium-water reaction. The hydrogen burn that occurred 9 h and 50 min after the initiation of the TMI-2 accident went essentially unnoticed for the first few days. Even through the burn increased the containment gas temperature and pressure to 12000F (6500C) and 29 lb/in2 (200 kPa) gage, there was no serious threat to the containment building. The processes, rates, and quantities of hydrogen gas generated and removed during and following the LOCA are described in this report. In addition, the methods which were used to define the conditions that existed in the containment building before, during, and after the hydrogen burn are described. The results of data evaluations and engineering calculations are presented to show the pressure and temperature histories of the atmosphere in various containment segments during and after the burn. Material and equipment in reactor containment buildings can be protected from burn damage by the use of relatively simple enclosures or insulation

  4. Effect of hydrogen on generation of lattice defects in shock-loaded Pd

    Energy Technology Data Exchange (ETDEWEB)

    Melikhova, Oksana, E-mail: oksivmel@yahoo.com [Charles University in Prague, Faculty of Mathematics and Physics, V Holešovičkách 2, CZ-180 00 Praha 8 (Czech Republic); Čížek, Jakub [Charles University in Prague, Faculty of Mathematics and Physics, V Holešovičkách 2, CZ-180 00 Praha 8 (Czech Republic); Chen, Yuzeng [State Key Laboratory of Solidification Processing, Northwestern Polytechnical University, 710072 Xi’an (China); Suo, Tao [School of Aeronautics, Northwestern Polytechnical University, 710072 Xi’an (China); Procházka, Ivan [Charles University in Prague, Faculty of Mathematics and Physics, V Holešovičkách 2, CZ-180 00 Praha 8 (Czech Republic); Liu, Feng [State Key Laboratory of Solidification Processing, Northwestern Polytechnical University, 710072 Xi’an (China)

    2015-10-05

    Highlights: • Influence of hydrogen on defect generation during shock-loading of Pd was examined. • Shock-loading introduced dislocations and vacancies. • Deformation-induced vacancies agglomerated into clusters consisting of 2–3 vacancies. • Absorbed hydrogen facilitates generation of both dislocations and vacancies. - Abstract: The effect of hydrogen absorbed in fcc Pd lattice on the generation of dislocations and vacancies during plastic deformation by shock-loading was investigated in this work. Well annealed bulk Pd samples were firstly charged with hydrogen up to various hydrogen concentrations. Subsequently the samples were shock-loaded on a Split-Hopkinson apparatus. Shock-loading yields extremely high strain rate and causes intensive plastic deformation of the samples. Lattice defects of the shock-loaded samples were characterized by positron lifetime spectroscopy combined with X-ray diffraction. It was found that shock-loaded Pd samples exhibit not only high density of dislocations but also small vacancy clusters created by agglomeration of deformation-induced vacancies. Pre-charging of Pd samples with hydrogen increases both the dislocation density and the concentration of vacancy clusters.

  5. Compositional controls on hydrogen generation during serpentinization of ultramafic rocks

    Science.gov (United States)

    Klein, Frieder; Bach, Wolfgang; McCollom, Thomas M.

    2013-09-01

    Where ultramafic rocks are exposed to water at temperatures talc ± magnetite (in addition to minor or trace phase like chlorite, tremolite, secondary diopside, garnet, Ni-Fe sulfides, alloys). In many circumstances, this process releases substantial amounts of hydrogen. Since the compositional controls of the primary lithology on the secondary mineralogy, fluid composition, Fe-distribution, and H2 formation are not well established, we used thermodynamic computations to examine the equilibrium mineral assemblages, mineral compositions and the chemistry of fluids during serpentinization of 21 different ultramafic rock compositions and 10 distinct compositions of olivine between 25 °C and 400 °C at 50 MPa. Our models predict some systematic differences between serpentinization of olivine-dominated lithologies (i.e. peridotite) and of orthopyroxene-dominated lithologies (i.e. pyroxenite). Most notably, it is predicted that serpentinization of peridotite causes the formation of serpentine having elevated Fe+ 3/(Fe+ 3 + Fe+ 2) values, Fe-bearing brucite (at temperatures ≤ ca. 320 °C), and magnetite (at temperatures > ca. 200 °C), while serpentinization of pyroxenite does not produce magnetite, but instead forms Fe-rich serpentine with relative low Fe+ 3/(Fe+ 3 + Fe+ 2) values and Fe-poor talc. The predicted activities of dissolved hydrogen (aH2(aq)), dissolved silica (aSiO2(aq)), as well as the pH vary accordingly. At temperatures ≤ ca. 350 °C, fluids interacting with peridotite are more reducing, have lower aSiO2(aq) and higher pH than fluids interacting with pyroxenite. A direct correlation between the iron content of olivine, its stability relative to water, temperature and aH2(aq) is apparent from our calculations. In contrast to forsterite-rich olivine, fayalite-rich olivine can be stable to temperatures as low as 180 °C in the presence of water. As a consequence, the predicted aH2(aq) for serpentinization of fayalite is maximal at temperatures ≤ 180 °C.

  6. High Performance, Low Cost Hydrogen Generation from Renewable Energy

    Energy Technology Data Exchange (ETDEWEB)

    Ayers, Katherine [Proton OnSite; Dalton, Luke [Proton OnSite; Roemer, Andy [Proton OnSite; Carter, Blake [Proton OnSite; Niedzwiecki, Mike [Proton OnSite; Manco, Judith [Proton OnSite; Anderson, Everett [Proton OnSite; Capuano, Chris [Proton OnSite; Wang, Chao-Yang [Penn State University; Zhao, Wei [Penn State University

    2014-02-05

    Renewable hydrogen from proton exchange membrane (PEM) electrolysis is gaining strong interest in Europe, especially in Germany where wind penetration is already at critical levels for grid stability. For this application as well as biogas conversion and vehicle fueling, megawatt (MW) scale electrolysis is required. Proton has established a technology roadmap to achieve the necessary cost reductions and manufacturing scale up to maintain U.S. competitiveness in these markets. This project represents a highly successful example of the potential for cost reduction in PEM electrolysis, and provides the initial stack design and manufacturing development for Proton’s MW scale product launch. The majority of the program focused on the bipolar assembly, from electrochemical modeling to subscale stack development through prototyping and manufacturing qualification for a large active area cell platform. Feasibility for an advanced membrane electrode assembly (MEA) with 50% reduction in catalyst loading was also demonstrated. Based on the progress in this program and other parallel efforts, H2A analysis shows the status of PEM electrolysis technology dropping below $3.50/kg production costs, exceeding the 2015 target.

  7. Evidence of catalytic production of hot hydrogen in rf generated hydrogen/argon plasmas

    CERN Document Server

    Phillips, J; Akhtar, K; Dhandapani, B; Mills, R; Phillips, Jonathan; Chen, Chun-Ku; Akhtar, Kamran; Dhandapani, Bala; Mills, Randell

    2005-01-01

    In this paper the selective broadening of the atomic hydrogen lines in pure H2 and Ar/H2 mixtures in a large 'GEC' cell (36 cm length_ 14 cm ID) was mapped as a function of position, H2/Ar ratio, time, power, and pressure. Several observations regarding the selective line broadening were particularly notable as they are unanticipated on the basis of earlier models. First, the anomalous broadening of the Balmer lines was found to exist throughout the plasma, and not just in the region between the electrodes. Second, the broadening was consistently a complex function of the operating parameters particularly gas composition (highest in pure H2), position, power, time and pressure. Clearly not anticipated by earlier models were the findings that under some conditions the highest concentration of 'hot' (>10 eV) hydrogen was found at the entry end, and not in the high field region between the electrodes and that in other conditions, the hottest H was at the (exit) pump (also grounded electrode) end. Third, excitati...

  8. Cobalt-Nanocrystal-Assembled Hollow Nanoparticles for Electrocatalytic Hydrogen Generation from Neutral-pH Water.

    Science.gov (United States)

    Liu, Bingrui; Zhang, Lin; Xiong, Weilin; Ma, Mingming

    2016-06-01

    Highly active and stable electrocatalysts for hydrogen generation from neutral-pH water are highly desired, but very difficult to achieve. Herein we report a facile synthetic approach to cobalt nanocrystal assembled hollow nanoparticles (Co-HNP), which serve as an electrocatalyst for hydrogen generation from neutral-pH water. An electrode composed of Co-HNP on a carbon cloth (CC) produces cathodic current densities of 10 and 100 mA cm(-2) at overpotentials of -85 mV and -237 mV, respectively. The Co-HNP/CC electrode retains its high activity after 20 h hydrogen generation at a high current density of 150 mA cm(-2) , indicating the superior activity and stability of Co-HNP as electrocatalyst. PMID:27125576

  9. In-vessel Zircaloy oxidation/hydrogen generation behavior during severe accidents

    International Nuclear Information System (INIS)

    In-vessel Zircaloy oxidation and hydrogen generation data from various US Nuclear Regulatory Commission severe-fuel damage test programs are presented and compared, where the effects of Zircaloy melting, bundle reconfiguration, and bundle quenching by reflooding are assessed for common findings. The experiments evaluated include fuel bundles incorporating fresh and previously irradiated fuel rods, as well as control rods. Findings indicate that the extent of bundle oxidation is largely controlled by steam supply conditions and that high rates of hydrogen generation continued after melt formation and relocation. Likewise, no retardation of hydrogen generation was noted for experiments which incorporated control rods. Metallographic findings indicate extensive oxidation of once-molten Zircaloy bearing test debris. Such test results indicate no apparent limitations to Zircaloy oxidation for fuel bundles subjected to severe-accident coolant-boiloff conditions. 46 refs., 22 figs., 12 tabs

  10. Stabilization of Wind Energy Conversion System with Hydrogen Generator by Using EDLC Energy Storage System

    Science.gov (United States)

    Shishido, Seiji; Takahashi, Rion; Murata, Toshiaki; Tamura, Junji; Sugimasa, Masatoshi; Komura, Akiyoshi; Futami, Motoo; Ichinose, Masaya; Ide, Kazumasa

    The spread of wind power generation is progressed hugely in recent years from a viewpoint of environmental problems including global warming. Though wind power is considered as a very prospective energy source, wind power fluctuation due to the random fluctuation of wind speed has still created some problems. Therefore, research has been performed how to smooth the wind power fluctuation. This paper proposes Energy Capacitor System (ECS) for the smoothing of wind power which consists of Electric Double-Layer Capacitor (EDLC) and power electronics devices and works as an electric power storage system. Moreover, hydrogen has received much attention in recent years from a viewpoint of exhaustion problem of fossil fuel. Therefore it is also proposed that a hydrogen generator is installed at the wind farm to generate hydrogen. In this paper, the effectiveness of the proposed system is verified by the simulation analyses using PSCAD/EMTDC.

  11. Carbon and hydrogen isotopic composition and generation pathway of biogenic gas in China

    Institute of Scientific and Technical Information of China (English)

    SHEN Ping; WANG Xiaofeng; XU Yin; SHI Baoguang; XU Yongchang

    2009-01-01

    The carbon and hydrogen isotopic composition of biogenic gas is of great importance for the study of its generation pathway and reservoiring characteristics. In this paper, the formation pathways and reservoiring characteristics of biogenic gas reservoirs in China are described in terms of the carbon and hydrogen isotopic compositions of 31 gas samples from 10 biogenic gas reservoirs. The study shows that the hydrogen isotopic compositions of these biogenic gas reservoirs can be divided into three intervals:δDCH4>-200‰,-250‰<δDCH4<-200‰ and δDCH4<-250‰. The forerunners believed that the main generation pathway of biogenic gas under the condition of continental fresh water is acetic fermentation. Our research results showed that the generation pathway of biogenic gas under the condition of marine facies is typical CO2- reduction, the biogenic gas has heavy hydrogen isotopic composition: its δDCH4 values are higher than -200‰; that the biogenic gas under the condition of continental facies also was generated by the same way, but its hydrogen isotopic composition is lighter than that of biogenetic gas generated under typical marine facies condition: -250‰<δDCH4<-200‰, the δDCH4 values may be related to the salinity of the water medium in ancient lakes. From the relevant data of the Qaidam Basin, it can be seen that the hydrogen isotopic composition of biogenic methane has the same variation trend with increasing salinity of water medium. There are biogenic gas reservoirs formed in transitional regions under the condition of continental facies. These gas reservoirs resulted from both CO2- reduction and acetic fermentation, the formation of which may be related to the non-variant salinity of ancient water medium and the relatively high geothermal gradient, as is the case encountered in the Baoshan Basin. The biogenic gas generating in these regions has light hydrogen isotopic composition: δDCH4<-250‰, and relatively heavy carbon isotopic

  12. Application of STATCOM/BESS for wind power smoothening and hydrogen generation

    Energy Technology Data Exchange (ETDEWEB)

    Muyeen, S.M.; Takahashi, Rion; Murata, Toshiaki; Tamura, Junji [Department of EEE, Kitami Institute of Technology, 165 Koen-cho, Hokkaido, Kitami 090-8507 (Japan); Ali, Mohd. Hasan [Department of Electrical and Computer Engineering, Ryerson University, 245 Church Street, Toronto (Canada)

    2009-02-15

    This paper proposes static synchronous compensator (STATCOM) incorporated with battery energy storage system (STATCOM/BESS) to smooth the line power of wind farm consists of fixed-speed wind generators. Constant output power reference is not a good choice because there may be some cases where wind speed is very low and then sufficient power cannot be obtained. In that case, energy storage device can solve the problem but large energy capacity may be needed. This paper proposes exponential moving average (EMA) to generate the reference output power, and thus the energy capacity of BESS unit can be small. Another salient feature of this study is the generation of hydrogen by using wind energy. At the wind farm terminal, two topologies of hydrogen generators are considered to be connected and their merits and demerits are analyzed. Finally, by taking the advantage of STATCOM/BESS, simple hydrogen generator topology composed of rectifier and electrolyzer is proposed. Detailed modeling and control strategy of hydrogen generator and STATCOM/BESS topologies are discussed and a cooperative control is developed. The effectiveness of the proposed system is verified by the simulation analysis using PSCAD/EMTDC. (author)

  13. Optimal generation scheduling for renewable microgrids using hydrogen storage systems

    OpenAIRE

    Petrollese, Mario

    2015-01-01

    The topic of this thesis is the development of a tool for an optimal energy management strategy (EMS) of the generators and energy storage systems constituent microgrids, both grid-connected or isolated (stand-alone power system) powered by Renewable Energy Sources (RES). In particular, a novel control system is designed based on the resolution of the unit commitment problem. For each time step, the proposed control system compares the expected power produced by the renewabl...

  14. Development status of solid polymer electrolyte water electrolysis for large scale hydrogen generation

    Science.gov (United States)

    Russell, J. H.

    1981-03-01

    Solid polymer water electrolysis technology for large scale hydrogen generation is reviewed. A hydrogen generator module, capable of producing 2000 SCFH, was operated successfully for over 700 hours in the 200 kW system. Test results and further information are presented. Technology development was continued in support of improving both capital cost and conversion efficiency. Progress made in the development of the 10 sq ft active area cell included completion of the initial design, the beginning of fabrication development, and installation of new facilities for cell manufacture.

  15. Generating hydrogen for mobile devices; Wasserstofferzeugung fuer die mobile Anwendung

    Energy Technology Data Exchange (ETDEWEB)

    Schuetz, W. [Vodafone Pilotentwicklung GmbH, Muenchen (Germany)

    2001-10-01

    In future vehicles, more and more functions will be powered by electricity. These are for example ''steer by wire'', ''break by wire'', air conditioning and infotainment. This growing demand for electricity is a new challenge for the automotive industry. The so called APU (auxilliary power unit) is a convincing solution. This power generating unit based on fuel cell technology will provide electrical power in all operation situations. The article deals with the main focus of P{sup 21}-power for the 21st century, the Mannesmann Fuel Cell Product Center of the Vodafone Pilotentwicklung. (orig.)

  16. Hydrogen generation in microbial reverse-electrodialysis electrolysis cells using a heat-regenerated salt solution.

    Science.gov (United States)

    Nam, Joo-Youn; Cusick, Roland D; Kim, Younggy; Logan, Bruce E

    2012-05-01

    Hydrogen gas can be electrochemically produced in microbial reverse-electrodialysis electrolysis cells (MRECs) using current derived from organic matter and salinity-gradient energy such as river water and seawater solutions. Here, it is shown that ammonium bicarbonate salts, which can be regenerated using low-temperature waste heat, can also produce sufficient voltage for hydrogen gas generation in an MREC. The maximum hydrogen production rate was 1.6 m(3) H(2)/m(3)·d, with a hydrogen yield of 3.4 mol H(2)/mol acetate at a salinity ratio of infinite. Energy recovery was 10% based on total energy applied with an energy efficiency of 22% based on the consumed energy in the reactor. The cathode overpotential was dependent on the catholyte (sodium bicarbonate) concentration, but not the salinity ratio, indicating high catholyte conductivity was essential for maximizing hydrogen production rates. The direction of the HC and LC flows (co- or counter-current) did not affect performance in terms of hydrogen gas volume, production rates, or stack voltages. These results show that the MREC can be successfully operated using ammonium bicarbonate salts that can be regenerated using conventional distillation technologies and waste heat making the MREC a useful method for hydrogen gas production from wastes. PMID:22463373

  17. Hydrogen Generation in Microbial Reverse-Electrodialysis Electrolysis Cells Using a Heat-Regenerated Salt Solution

    KAUST Repository

    Nam, Joo-Youn

    2012-05-01

    Hydrogen gas can be electrochemically produced in microbial reverse-electrodialysis electrolysis cells (MRECs) using current derived from organic matter and salinity-gradient energy such as river water and seawater solutions. Here, it is shown that ammonium bicarbonate salts, which can be regenerated using low-temperature waste heat, can also produce sufficient voltage for hydrogen gas generation in an MREC. The maximum hydrogen production rate was 1.6 m3 H2/m3·d, with a hydrogen yield of 3.4 mol H2/mol acetate at a salinity ratio of infinite. Energy recovery was 10% based on total energy applied with an energy efficiency of 22% based on the consumed energy in the reactor. The cathode overpotential was dependent on the catholyte (sodium bicarbonate) concentration, but not the salinity ratio, indicating high catholyte conductivity was essential for maximizing hydrogen production rates. The direction of the HC and LC flows (co- or counter-current) did not affect performance in terms of hydrogen gas volume, production rates, or stack voltages. These results show that the MREC can be successfully operated using ammonium bicarbonate salts that can be regenerated using conventional distillation technologies and waste heat making the MREC a useful method for hydrogen gas production from wastes. © 2012 American Chemical Society.

  18. Coupling a PEM fuel cell and the hydrogen generation from aluminum waste cans

    Energy Technology Data Exchange (ETDEWEB)

    Martinez, Susana Silva; Albanil Sanchez, Loyda; Alvarez Gallegos, Alberto A. [Centro de Investigacion en Ingenieria y Ciencias Aplicadas, Av. Universidad 1001, Col. Chamilpa, Cuernavaca, Mor. CP 62210 (Mexico); Sebastian, P.J. [Centro de Investigacion en Energia-UNAM, 62580 Temixco, Morelos (Mexico); Cuerpo Academico de Energia y Sustentabilidad, UPCH, Tuxtla Gutierrez, Chiapas (Mexico)

    2007-10-15

    High purity hydrogen was generated from the chemical reaction of aluminum and sodium hydroxide. The aluminum used in this study was obtained from empty soft drink cans and treated with concentrated sulfuric acid to remove the paint and plastic film. One gram of aluminum was reacted with a solution of 2moldm{sup -3} of sodium hydroxide to produce hydrogen. The hydrogen produced from aluminum cans and oxygen obtained from a proton exchange membrane electrolyzer or air, was fed to a proton exchange membrane (PEM) fuel cell to produce electricity. Yields of 44 mmol of hydrogen contained in a volume of 1.760dm{sup 3} were produced from one gram of aluminum in a time period of 20 min. (author)

  19. Understanding oscillatory phenomena in molecular hydrogen generation via sodium borohydride hydrolysis.

    Science.gov (United States)

    Budroni, M A; Biosa, E; Garroni, S; Mulas, G R C; Marchettini, N; Culeddu, N; Rustici, M

    2013-11-14

    The hydrolysis of borohydride salts represents one of the most promising processes for the generation of high purity molecular hydrogen under mild conditions. In this work we show that the sodium borohydride hydrolysis exhibits a fingerprinting periodic oscillatory transient in the hydrogen flow over a wide range of experimental conditions. We disproved the possibility that flow oscillations are driven by supersaturation phenomena of gaseous bubbles in the reactive mixture or by a nonlinear thermal feedback according to a thermokinetic model. Our experimental results indicate that the NaBH4 hydrolysis is a spontaneous inorganic oscillator, in which the hydrogen flow oscillations are coupled to an "oscillophor" in the reactive solution. The discovery of this original oscillator paves the way for a new class of chemical oscillators, with fundamental implications not only for testing the general theory on oscillations, but also with a view to chemical control of borohydride systems used as a source of hydrogen based green fuel. PMID:24084866

  20. Estudio cinético de la descomposición catalizada de peróxido de hidrógeno sobre carbón activado Kinetic study of the catalyzed decomposition of hydrogen peroxide on activated carbon

    Directory of Open Access Journals (Sweden)

    Elihu Paternina

    2009-01-01

    Full Text Available The kinetic study of decomposition of hydrogen peroxide catalyzed by activated carbon was carried out. The effect of concentrations of reactants and temperature were experimentally studied. Kinetic data were evaluated using differential method of initial rates of reaction. When a typical kinetic law for reactions in homogeneous phase is used, first order of reaction is obtained for hydrogen peroxide and activated carbon, and activation energy of 27 kJ mol-1 for the reaction was estimated. Experimentally was observed that surface of activated carbon is chemically modified during decomposition of hydrogen peroxide, based on this result a scheme of reaction was proposed and evaluated. Experimental data fits very well to a Langmuir- Hinshelwood kinetic model and activation energy of 40 kJ mol-1 was estimated for reaction in heterogeneous phase.

  1. Hydrogen generation in SRAT with nitric acid and late washing flowsheets

    International Nuclear Information System (INIS)

    Melter feed preparation processes, incorporating a final wash of the precipitate slurry feed to Defense Waste Processing Facility (DWPF) and a partial substitution of the SRAT formic acid requirement with nitric acid, should not produce peak hydrogen generation rates during Cold Chemical Runs (CCR's) and radioactive operation greater than their current, respective hydrogen design bases of 0.024 lb/hr and 1.5 lb/hr. A single SRAT bench-scale process simulation for CCR-s produced a DWPF equivalent peak hydrogen generation rate of 0.004 lb/hr. During radioactive operation, the peak hydrogen generation rate will be dependent on the extent DWPF deviates from the nominal precipitate hydrolysis and melter feed preparation process operating parameters. Two actual radioactive sludges were treated according to the new flowsheets. The peak hydrogen evolution rates were equivalent to 0.038 and 0.20 lb/hr (DWPF scale) respectively. Compared to the formic acid -- HAN hydrolysis flowsheets, these peak rates were reduced by a factor of 2.5 and 3.4 for Tank 15 and Tank 11 sludges, respectively

  2. Hydrogen-generating reactions in LWR severe accidents

    International Nuclear Information System (INIS)

    The available data on the reactions of Zircaloys, stainless steels, uranium metal and uranium dioxide with steam at temperatures above about 10000C and the reactions of core melts during concrete penetration have been reviewed and assessed for the IDCOR Program. The uranium metal is included because small quantities can be formed from the high temperature interaction between Zircaloy and uranium dioxide and because the uranium data adds insight into the nature of the reactions of core materials with steam. Thermodynamic analyses and comparisons of reaction rate data have been made. One of the purposes of this assessment was to develop fully the information generated in the early studies of oxidation processes, particularly the extensive program carried out at ANL from about 1960 to 1968

  3. WTP Waste Feed Qualification: Hydrogen Generation Rate Measurement Apparatus Testing Report

    Energy Technology Data Exchange (ETDEWEB)

    Stone, M. E. [Savannah River Site (SRS), Aiken, SC (United States). Savannah River National Lab. (SRNL); Newell, J. D. [Savannah River Site (SRS), Aiken, SC (United States). Savannah River National Lab. (SRNL); Smith, T. E. [Savannah River Site (SRS), Aiken, SC (United States). Savannah River National Lab. (SRNL); Pareizs, J. M. [Savannah River Site (SRS), Aiken, SC (United States). Savannah River National Lab. (SRNL)

    2016-06-01

    The generation rate of hydrogen gas in the Hanford tank waste will be measured during the qualification of the staged tank waste for processing in the Hanford Tank Waste Treatment and Immobilization Plant. Based on a review of past practices in measurement of the hydrogen generation, an apparatus to perform this measurement has been designed and tested for use during waste feed qualification. The hydrogen generation rate measurement apparatus described in this document and shown in Figure 0-1 utilized a 100 milliliter sample in a continuously-purged, continuously-stirred vessel, with measurement of hydrogen concentration in the vent gas. The vessel and lid had a combined 220 milliliters of headspace. The vent gas system included a small condenser to prevent excessive evaporative losses from the sample during the test, as well as a demister and filter to prevent particle migration from the sample to the gas chromatography system. The gas chromatograph was an on line automated instrument with a large-volume sample-injection system to allow measurement of very low hydrogen concentrations. This instrument automatically sampled the vent gas from the hydrogen generation rate measurement apparatus every five minutes and performed data regression in real time. The fabrication of the hydrogen generation rate measurement apparatus was in accordance with twenty three (23) design requirements documented in the conceptual design package, as well as seven (7) required developmental activities documented in the task plan associated with this work scope. The HGRMA was initially tested for proof of concept with physical simulants and a remote demonstration of the system was performed in the Savannah River National Laboratory Shielded Cells Mockup Facility. Final verification testing was performed using non-radioactive simulants of the Hanford tank waste. Three different simulants were tested to bound the expected rheological properties expected during waste feed qualification

  4. Muon-catalyzed fusion-an energy production perspective

    International Nuclear Information System (INIS)

    The nuclear fission reaction can be catalyzed in a suitable fusion fuel by muons, which can temporarily form very tightly bound mu-molecules. Muons can be produced by the decay of negative pions, which, in turn, have been produced by an accelerated beam of light ions impinging on a target. Muon-catalyzed fusion is appropriately called cold fusion because the nuclear fusion also occurs at room temperature. For practical fusion energy generation, it appears to be necessary to have a fuel mixture of deuterium and tritium at about liquid density and at a temperature of the order of 1000 K. The current status of muon-catalyzed fusion is limited to demonstrations of scientific breakeven by showing that it is possible to sustain an energy balance between muon production and catalyzed fusion. Conceptually, a muon-catalyzed fusion reactor is seen to be an energy amplifier that increases by fusion reactions that energy invested in nuclear pion-muon beams. The physical quantity that determines this balance is Xμ, the number of fusion reactions each muon can catalyze before it is lost. Showing the feasibility of useful power production is equivalent to showing that Xμ can exceed a sufficiently large number, which is estimated to be ∼104 if standard technology is used or ∼103 if more advanced physics and technology can be developed. Since a muon can be produced with current technology for an expenditure of ∼5000 MeV and 17.6 MeV is produced per fusion event, it follows that Xμ ∼ 250 would be a significant demonstration of scientific breakeven. Therefore, the energy cost of producing muons must be reduced substantially before muon-catalyzed fusion reactors could seriously be considered. The physics of muon-catalyzed fusion is summarized and discussed. Muon catalysis is surveyed for the following systems: proton-deuteron, deuteron-deuteron, deuteron-triton, and non-hydrogen elements. 95 refs., 6 figs., 4 tabs

  5. Chemiluminescence assay for catechin based on generation of hydrogen peroxide in basic solution

    International Nuclear Information System (INIS)

    We have determined that the catechin group in basic solution efficiently produces hydrogen peroxide; moreover, a highly sensitive analysis methodology was developed to measure catechin employing a peroxalate chemiluminescence detection system. Identification of hydrogen peroxide generated by catechin was determined by ESR as well as peroxalate chemiluminescence using catalase and SOD. As a result, catechin-generated superoxide by electron reduction to dissolved oxygen in basic solution, followed by production of hydrogen peroxide through dismutation reaction. This method could measure several tea catechins, (+)-catechin (CC), (-)-epigallocatechin-3-gallate (EGCg), (-)-epicatechin-3-gallate (ECG) and gallic acid, with measurement range from 10-7 to 10-3 mol/l and sensitivity of 10-8 mol/l. This method was also applied to the determination of total catechin levels in green tea, black tea and roasted green tea

  6. Start up system for hydrogen generator used with an internal combustion engine

    Science.gov (United States)

    Houseman, J.; Cerini, D. J. (Inventor)

    1977-01-01

    A hydrogen generator provides hydrogen rich product gases which are mixed with the fuel being supplied to an internal combustion engine for the purpose of enabling a very lean mixture of that fuel to be used, whereby nitrous oxides emitted by the engine are minimized. The hydrogen generator contains a catalyst which must be heated to a pre-determined temperature before it can react properly. To simplify the process of heating up the catalyst at start-up time, either some of the energy produced by the engine such as engine exhaust gas, or electrical energy produced by the engine, or the engine exhaust gas may be used to heat up air which is then used to heat the catalyst.

  7. HIGH EFFICIENCY GENERATION OF HYDROGEN FUELS USING NUCLEAR POWER FINAL RECHNICAL REPORT FOR THE PERIOD AUGUST 1, 1999 THROUGH SEPTEMBER 30, 2002 REV. 1

    Energy Technology Data Exchange (ETDEWEB)

    BROWN,LC; BESENBRUCH,GE; LENTSCH, RD; SCHULTZ,KR; FUNK,JF; PICKARD,PS; MARSHALL,AC; SHOWALTER,SK

    2003-12-01

    carbon monoxide) that are detrimental to precious metal catalyzed fuel cells, as is now recognized by many of the world's largest automobile companies. Thermochemical hydrogen will not contain carbon monoxide as an impurity at any level. Electrolysis, the alternative process for producing hydrogen using nuclear energy, suffers from thermodynamic inefficiencies in both the production of electricity and in electrolytic parts of the process. The efficiency of electrolysis (electricity to hydrogen) is currently about 80%. Electric power generation efficiency would have to exceed 65% (thermal to electrical) for the combined efficiency to exceed the 52% (thermal to hydrogen) calculated for one thermochemical cycle. Thermochemical water-splitting cycles have been studied, at various levels of effort, for the past 35 years. They were extensively studied in the late 70s and early 80s but have received little attention in the past 10 years, particularly in the U.S. While there is no question about the technical feasibility and the potential for high efficiency, cycles with proven low cost and high efficiency have yet to be developed commercially. Over 100 cycles have been proposed, but substantial research has been executed on only a few. This report describes work accomplished during a three-year project whose objective is to ''define an economically feasible concept for production of hydrogen, by nuclear means, using an advanced high temperature nuclear reactor as the energy source.''

  8. Fuel processor and method for generating hydrogen for fuel cells

    Science.gov (United States)

    Ahmed, Shabbir; Lee, Sheldon H. D.; Carter, John David; Krumpelt, Michael; Myers, Deborah J.

    2009-07-21

    A method of producing a H.sub.2 rich gas stream includes supplying an O.sub.2 rich gas, steam, and fuel to an inner reforming zone of a fuel processor that includes a partial oxidation catalyst and a steam reforming catalyst or a combined partial oxidation and stream reforming catalyst. The method also includes contacting the O.sub.2 rich gas, steam, and fuel with the partial oxidation catalyst and the steam reforming catalyst or the combined partial oxidation and stream reforming catalyst in the inner reforming zone to generate a hot reformate stream. The method still further includes cooling the hot reformate stream in a cooling zone to produce a cooled reformate stream. Additionally, the method includes removing sulfur-containing compounds from the cooled reformate stream by contacting the cooled reformate stream with a sulfur removal agent. The method still further includes contacting the cooled reformate stream with a catalyst that converts water and carbon monoxide to carbon dioxide and H.sub.2 in a water-gas-shift zone to produce a final reformate stream in the fuel processor.

  9. Prostaglandins attenuate cardiac contractile dysfunction produced by free radical generation but not by hydrogen peroxide.

    Science.gov (United States)

    Zimmer, K M; Karmazyn, M

    1997-11-01

    The aim of this study was to examine and compare the potential influence of cyclooxygenase or lipoxygenase derived metabolites of arachidonic acid on myocardial injury produced either by a free radical generating system consisting of purine plus xanthine oxidase or that produced by hydrogen peroxide. A free radical generating system consisting of purine (2.3 mM) and xanthine oxidase (10 U/L) as well as hydrogen peroxide (75 microM) produced significant functional changes in the absence of either significant deficits in high energy phosphates or ultrastructural damage. Prostaglandin F2 alpha (30 nM) significantly attenuated both the negative inotropic effect of purine plus xanthine oxidase as well as the ability of the free radical generator to elevate diastolic pressure. An identical concentration of prostaglandin 12 (prostacyclin) significantly reduced diastolic pressure elevation only and had no effect on contractile depression. The salutary effects of the two PGs occurred in the absence of any inhibitory influence on superoxide anion generation produced by the purine and xanthine oxidase reaction. None of prostaglandins modulated the response to hydrogen peroxide. In addition, neither prostaglandin E2 nor leukotrienes exerted any effect on changes produced by either type of oxidative stress. A 5 fold elevation in the concentrations of free radical generators or hydrogen peroxide produced extensive injury as characterized by a virtual total loss in contractility, 400% elevation in diastolic pressure, ultrastructural damage and significant depletions in high energy phosphate content. None of these effects were modulated by eicosanoid treatment. Our results therefore demonstrate a selective ability of both prostaglandin F2 alpha and to a lesser extent prostacyclin, to attenuate dysfunction produced by purine plus xanthine oxidase but not hydrogen peroxide. It is possible that these eicosanoids may represent endogenous protective factors under conditions of enhanced

  10. High Efficiency Generation of Hydrogen Fuels using Nuclear Power Annual Report August, 2000 - July 2001

    Energy Technology Data Exchange (ETDEWEB)

    Brown, L.C.

    2002-11-01

    OAK B188 High Efficiency Generation of Hydrogen Fuels using Nuclear Power Annual Report August 2000 - July 2001. Currently no large scale, cost-effective, environmentally attractive hydrogen production process is available for commercialization nor has such a process been identified. Hydrogen is a promising energy carrier, which potentially could replace the fossil fuels used in the transportation sector of our economy. Carbon dioxide emissions from fossil fuel combustion are thought to be responsible for global warming. The purpose of this work is to determine the potential for efficient, cost-effective, large-scale production of hydrogen utilizing high temperature heat from an advanced nuclear power station. The benefits of this work will include the generation of a low-polluting transportable energy feedstock in an efficient method that has little or no implication for greenhouse gas emissions from a primary energy source whose availability and sources are domestically controlled. This will help to ensure energy for a future transportation/energy infrastructure that is not influenced/controlled by foreign governments. This report describes work accomplished during the second year (Phase 2) of a three year project whose objective is to ''define an economically feasible concept for production of hydrogen, by nuclear means, using an advanced high temperature nuclear reactor as the energy source.'' The emphasis of the first year (Phase 1) was to evaluate thermochemical processes which offer the potential for efficient, cost-effective, large-scale production of hydrogen from water, in which the primary energy input is high temperature heat from an advanced nuclear reactor and to select one (or, at most, three) for further detailed consideration. Phase 1 met its goals and did select one process, the sulfur-iodine process, for investigation in Phases 2 and 3. The combined goals of Phases 2 and 3 were to select the advanced nuclear reactor best

  11. Modeling the reaction kinetics of a hydrogen generator onboard a fuel cell -- Electric hybrid motorcycle

    Science.gov (United States)

    Ganesh, Karthik

    Owing to the perceived decline of the fossil fuel reserves in the world and environmental issues like pollution, conventional fuels may be replaced by cleaner alternative fuels. The potential of hydrogen as a fuel in vehicular applications is being explored. Hydrogen as an energy carrier potentially finds applications in internal combustion engines and fuel cells because it is considered a clean fuel and has high specific energy. However, at 6 to 8 per kilogram, not only is hydrogen produced from conventional methods like steam reforming expensive, but also there are storage and handling issues, safety concerns and lack of hydrogen refilling stations across the country. The purpose of this research is to suggest a cheap and viable system that generates hydrogen on demand through a chemical reaction between an aluminum-water slurry and an aqueous sodium hydroxide solution to power a 2 kW fuel cell on a fuel cell hybrid motorcycle. This reaction is essentially an aluminum-water reaction where sodium hydroxide acts as a reaction promoter or catalyst. The Horizon 2000 fuel cell used for this purpose has a maximum hydrogen intake rate of 28 lpm. The study focuses on studying the exothermic reaction between the reactants and proposes a rate law that best describes the rate of generation of hydrogen in connection to the surface area of aluminum available for the certain reaction and the concentration of the sodium hydroxide solution. Further, the proposed rate law is used in the simulation model of the chemical reactor onboard the hybrid motorcycle to determine the hydrogen flow rate to the fuel cell with time. Based on the simulated rate of production of hydrogen from the chemical system, its feasibility of use on different drive cycles is analyzed. The rate of production of hydrogen with a higher concentration of sodium hydroxide and smaller aluminum powder size was found to enable the installation of the chemical reactor on urban cycles with frequent stops and starts

  12. Biomass & Natural Gas Based Hydrogen Fuel For Gas Turbine (Power Generation)

    Science.gov (United States)

    Significant progress has been made by major power generation equipment manufacturers in the development of market applications for hydrogen fuel use in gas turbines in recent years. Development of a new application using gas turbines for significant reduction of power plant CO2 e...

  13. Hydrogen generation by water radiolysis with immersion of oxidation products of Zircaloy-4

    International Nuclear Information System (INIS)

    In order to predict the hydrogen gas generation from seawater or water in which debris would be included by the severe accident of nuclear power plant, we investigated the effect of ZrO2 and the oxidation products of Zircaloy-4 on hydrogen gas generation by radiolysis of water since the radiolytic generation could be affected by materials immersed in water. Powders of well-characterized oxides and oxidation products were immersed in either seawater or distilled water, and irradiated by gamma ray from a Co-60 source. The observed hydrogen yield, G(H2), was measured as a function of the weight fraction of oxide in water up to 50 wt%. The enhancement of the hydrogen generation by radiolysis of water with the commercial oxides and the oxidation products of Zircaloy-4 was quite small or absent in seawater. But the enhancement was observed in the presence of the oxides or the oxidation products at low weight fraction in distilled water. This enhancement in distilled water seemed to be dependent on specific surface area or particle size, but its dependence on the crystal structure was not apparent in the experimental results. The enhancement was saturated at higher ZrO2 weight fractions and it was not apparent in the seawater. (author)

  14. Status of the development of solid polymer electrolyte water electrolysis for large scale hydrogen generation

    Science.gov (United States)

    Russell, J. H.

    1982-02-01

    Solid polymer electrolyte water electrolysis for large scale hydrogen generation is reported. The program was aimed at performance improvement. Reductions in cell impedance were demonstrated which improve cell performance by over 100 mV. A prototype 500 SCFH system for field evaluation was developed.

  15. Interaction of gas phase atomic hydrogen with Pt(111): Direct evidence for the formation of bulk hydrogen species

    Institute of Scientific and Technical Information of China (English)

    JIANG ZhiQuan; HUANG WeiXin; BAO XinHe

    2007-01-01

    Employing hot tungsten filament to thermal dissociate molecular hydrogen, we generated gas phase atomic hydrogen under ultra-high vacuum (UHV) conditions and investigated its interaction with Pt(111) surface. Thermal desorption spectroscopy (TDS) results demonstrate that adsorption of molecular hydrogen on Pt(111) forms surface Had species whereas adsorption of atomic hydrogen forms not only surface Had species but also bulk Had species. Bulk Had species is more thermal-unstable than surface Had species on Pt(111), suggesting that bulk Had species is more energetic. This kind of weakly- adsorbed bulk Had species might be the active hydrogen species in the Pt-catalyzed hydrogenation reactions.

  16. Evaluation of the pressure loads generated by hydrogen explosion in auxiliary nuclear building

    International Nuclear Information System (INIS)

    Full text of publication follows: In the framework of nuclear safety, a hydrogen leaks in the auxiliary nuclear building would raise a explosion hazard. A local ignition of the combustible mixture would give birth initially to a slow flame, rapidly accelerated by obstacles. This flame acceleration is responsible for high pressure loads that can damage the auxiliary building and destroy safety equipments in it. In this paper, we evaluate the pressure loads generated by an hydrogen explosion for both bounding and realistic explosion scenarios. The bounding scenarios use stoichiometric hydrogen-air mixtures and the realistic scenarios correspond to hydrogen leaks with mass flow rate varying between 1 g/s and 9 g/s. For every scenario, the impact of the ignition location and ignition time are investigated. The hydrogen dispersion and explosion are computed using the TONUS code. The dispersion model used is based on a finite element solver and the explosion is simulated by a structured finite volumes EULER equation solver and the combustion model CREBCOM which simulates the hydrogen/air turbulent flame propagation, taking into account 3D complex geometry and reactants concentration gradients. The pressure loads computed are then used to investigate the occurrence of a mechanical failure of the tanks located in the auxiliary nuclear building and containing radioactive fluids. The EUROPLEXUS code is used to perform 3D mechanical calculations because the loads are non uniform and of rather short deviation. (authors)

  17. A polymer electrolyte fuel cell stack for stationary power generation from hydrogen fuel

    Energy Technology Data Exchange (ETDEWEB)

    Gottesfeld, S. [Los Alamos National Lab., NM (United States)

    1995-09-01

    The fuel cell is the most efficient device for the conversion of hydrogen fuel to electric power. As such, the fuel cell represents a key element in efforts to demonstrate and implement hydrogen fuel utilization for electric power generation. The low temperature, polymer electrolyte membrane fuel cell (PEMFC) has recently been identified as an attractive option for stationary power generation, based on the relatively simple and benign materials employed, the zero-emission character of the device, and the expected high power density, high reliability and low cost. However, a PEMFC stack fueled by hydrogen with the combined properties of low cost, high performance and high reliability has not yet been demonstrated. Demonstration of such a stack will remove a significant barrier to implementation of this advanced technology for electric power generation from hydrogen. Work done in the past at LANL on the development of components and materials, particularly on advanced membrane/electrode assemblies (MEAs), has contributed significantly to the capability to demonstrate in the foreseeable future a PEMFC stack with the combined characteristics described above. A joint effort between LANL and an industrial stack manufacturer will result in the demonstration of such a fuel cell stack for stationary power generation. The stack could operate on hydrogen fuel derived from either natural gas or from renewable sources. The technical plan includes collaboration with a stack manufacturer (CRADA). It stresses the special requirements from a PEMFC in stationary power generation, particularly maximization of the energy conversion efficiency, extension of useful life to the 10 hours time scale and tolerance to impurities from the reforming of natural gas.

  18. A third-generation dispersion and third-generation hydrogen bonding corrected PM6 method

    DEFF Research Database (Denmark)

    Kromann, Jimmy Charnley; Christensen, Anders Steen; Svendsen, Casper Steinmann;

    2014-01-01

    We present new dispersion and hydrogen bond corrections to the PM6 method, PM6-D3H+, and its implementation in the GAMESS program. The method combines the DFT-D3 dispersion correction by Grimme et al. with a modified version of the H+ hydrogen bond correction by Korth. Overall, the interaction en...... computing vibrational free energies. While the GAMESS implementation is up to 10 times slower for geometry optimizations of proteins in bulk solvent, compared to MOPAC, it is sufficiently fast to make geometry optimizations of small proteins practically feasible....... energy of PM6-D3H+ is very similar to PM6-DH2 and PM6-DH+, with RMSD and MAD values within 0.02 kcal/mol of one another. The main difference is that the geometry optimizations of 88 complexes result in 82, 6, 0, and 0 geometries with 0, 1, 2, and 3 or more imaginary frequencies using PM6-D3H+ implemented...

  19. NOBLE METAL CHEMISTRY AND HYDROGEN GENERATION DURING SIMULATED DWPF MELTER FEED PREPARATION

    Energy Technology Data Exchange (ETDEWEB)

    Koopman, D

    2008-06-25

    Simulations of the Defense Waste Processing Facility (DWPF) Chemical Processing Cell vessels were performed with the primary purpose of producing melter feeds for the beaded frit program plus obtaining samples of simulated slurries containing high concentrations of noble metals for off-site analytical studies for the hydrogen program. Eight pairs of 22-L simulations were performed of the Sludge Receipt and Adjustment Tank (SRAT) and Slurry Mix Evaporator (SME) cycles. These sixteen simulations did not contain mercury. Six pairs were trimmed with a single noble metal (Ag, Pd, Rh, or Ru). One pair had all four noble metals, and one pair had no noble metals. One supporting 4-L simulation was completed with Ru and Hg. Several other 4-L supporting tests with mercury have not yet been performed. This report covers the calculations performed on SRNL analytical and process data related to the noble metals and hydrogen generation. It was originally envisioned as a supporting document for the off-site analytical studies. Significant new findings were made, and many previous hypotheses and findings were given additional support as summarized below. The timing of hydrogen generation events was reproduced very well within each of the eight pairs of runs, e.g. the onset of hydrogen, peak in hydrogen, etc. occurred at nearly identical times. Peak generation rates and total SRAT masses of CO{sub 2} and oxides of nitrogen were reproduced well. Comparable measures for hydrogen were reproduced with more variability, but still reasonably well. The extent of the reproducibility of the results validates the conclusions that were drawn from the data.

  20. Comparative study of the hydrogen generation during short term station blackout (STSBO) in a BWR

    International Nuclear Information System (INIS)

    Highlights: • Comparative study of generation in a simulated STSBO severe accident. • MELCOR and SCDAP/RELAP5 codes were used to understanding the main phenomena. • Both codes present similar thermal-hydraulic behavior for pressure and boil off. • SCDAP/RELAP5 predicts 15.8% lower hydrogen production than MELCOR. - Abstract: The aim of this work is the comparative study of hydrogen generation and the associated parameters in a simulated severe accident of a short-term station blackout (STSBO) in a typical BWR-5 with Mark-II containment. MELCOR (v.1.8.6) and SCDAP/RELAP5 (Mod.3.4) codes were used to understand the main phenomena in the STSBO event through the results comparison obtained from simulations with these codes. Due that the simulation scope of SCDAP/RELAP5 is limited to failure of the vessel pressure boundary, the comparison was focused on in-vessel severe accident phenomena; with a special interest in the vessel pressure, boil of cooling, core temperature, and hydrogen generation. The results show that at the beginning of the scenario, both codes present similar thermal-hydraulic behavior for pressure and boil off of cooling, but during the relocation, the pressure and boil off, present differences in timing and order of magnitude. Both codes predict in similar time the beginning of melting material drop to the lower head. As far as the hydrogen production rate, SCDAP/RELAP5 predicts 15.8% lower production than MELCOR

  1. Thermodynamic analysis of a solar-based multi-generation system with hydrogen production

    International Nuclear Information System (INIS)

    Thermodynamic analysis of a renewable-based multi-generation energy production system which produces a number of outputs, such as power, heating, cooling, hot water, hydrogen and oxygen is conducted. This solar-based multi-generation system consists of four main sub-systems: Rankine cycle, organic Rankine cycle, absorption cooling and heating, and hydrogen production and utilization. Exergy destruction ratios and rates, power or heat transfer rates, energy and exergy efficiencies of the system components are carried out. Some parametric studies are performed in order to examine the effects of varying operating conditions (e.g., reference temperature, direct solar radiation and receiver temperature) on the exergy efficiencies of the sub-systems as well as the whole system. The solar-based multi-generation system which has an exergy efficiency of 57.35%, is obtained to be higher than using these sub-systems separately. The evaluation of the exergy efficiency and exergy destruction for the sub-systems and the overall system show that the parabolic dish collectors have the highest exergy destruction rate among constituent parts of the solar-based multi-generation system, due to high temperature difference between the working fluid and collector receivers. -- Highlights: ► Development of a new multi-generation system for solar-based hydrogen production. ► Investigation of exergy efficiencies and destructions in each process of the system. ► Evaluation of varying operating conditions on the exergy destruction and efficiency

  2. Hydrogen generation from hydrolysis of sodium borohydride using Ru(0) nanoclusters as catalyst

    International Nuclear Information System (INIS)

    Sodium borohydride is stable in aqueous alkaline solution, however, it hydrolyses in water to hydrogen gas in the presence of suitable catalyst. By this way hydrogen can be generated safely for the fuel cells. Generating H2 catalytically from NaBH4 solutions has many advantages: NaBH4 solutions are nonflammable, reaction products are environmentally benign, rate of H2 generation is easily controlled, the reaction product NaBO2 can be recycled, H2 can be generated even at low temperatures. All of the catalysts that has been used in hydrolysis of sodium borohydride are bulk metals and they act as heterogeneous catalysts. The limited surface area of the heterogeneous catalysts causes lower catalytic activity as the activity of catalyst is directly related to its surface area. Thus, the use of metal nanoparticles with large surface area provides potential route to increase the catalytic activity. Here, we report, for the first time, the use of ruthenium(0) nanoclusters as catalyst in the hydrolysis of sodium borohydride liberating hydrogen gas. The ruthenium nanoparticles are generated from the reduction of ruthenium(III) chloride by sodium borohydride in water and stabilized by specific ligand. The ruthenium(0) nanoclusters are found to be highly active catalyst for the hydrolysis of sodium borohydride

  3. Large area imaging of hydrogenous materials using fast neutrons from a DD fusion generator

    International Nuclear Information System (INIS)

    A small-laboratory fast-neutron generator and a large area detector were used to image hydrogen-bearing materials. The overall image resolution of 2.5 mm was determined by a knife-edge measurement. Contact images of objects were obtained in 5–50 min exposures by placing them close to a plastic scintillator at distances of 1.5 to 3.2 m from the neutron source. The generator produces 109 n/s from the DD fusion reaction at a small target. The combination of the DD-fusion generator and electronic camera permits both small laboratory and field-portable imaging of hydrogen-rich materials embedded in high density materials.

  4. High Efficiency Generation of Hydrogen Fuels Using Solar Thermochemical Splitting of Water

    Energy Technology Data Exchange (ETDEWEB)

    Heske, Clemens; Moujaes, Samir; Weimer, Alan; Wong, Bunsen; Siegal, Nathan; McFarland, Eric; Miller, Eric; Lewis, Michele; Bingham, Carl; Roth, Kurth; Sabacky, Bruce; Steinfeld, Aldo

    2011-09-29

    The objective of this work is to identify economically feasible concepts for the production of hydrogen from water using solar energy. The ultimate project objective was to select one or more competitive concepts for pilot-scale demonstration using concentrated solar energy. Results of pilot scale plant performance would be used as foundation for seeking public and private resources for full-scale plant development and testing. Economical success in this venture would afford the public with a renewable and limitless source of energy carrier for use in electric power load-leveling and as a carbon-free transportation fuel. The Solar Hydrogen Generation Research (SHGR) project embraces technologies relevant to hydrogen research under the Office of Hydrogen Fuel Cells and Infrastructure Technology (HFCIT) as well as concentrated solar power under the Office of Solar Energy Technologies (SET). Although the photoelectrochemical work is aligned with HFCIT, some of the technologies in this effort are also consistent with the skills and technologies found in concentrated solar power and photovoltaic technology under the Office of Solar Energy Technologies (SET). Hydrogen production by thermo-chemical water-splitting is a chemical process that accomplishes the decomposition of water into hydrogen and oxygen using only heat or a combination of heat and electrolysis instead of pure electrolysis and meets the goals for hydrogen production using only water and renewable solar energy as feed-stocks. Photoelectrochemical hydrogen production also meets these goals by implementing photo-electrolysis at the surface of a semiconductor in contact with an electrolyte with bias provided by a photovoltaic source. Here, water splitting is a photo-electrolytic process in which hydrogen is produced using only solar photons and water as feed-stocks. The thermochemical hydrogen task engendered formal collaborations among two universities, three national laboratories and two private sector

  5. Revaluation of hydrogen generation by water radiolysis in SDS vessels at TMI-2 accident

    International Nuclear Information System (INIS)

    Two years after Three Mile Island Unit 2 (TMI-2) loss-of-coolant accident, radioactive contaminated water has been processed by Submerged Demineralizer System (SDS) with two types of zeolite adsorbents to remove radioactive nuclides of Sr-90, Cs-134 and Cs-137. During and after the process, adsorption amount and distribution of nuclides on the zeolites, residual water content and thermal conductivity in the SDS vessels have been measured or estimated for verification of safety in the process, subsequent transportation and disposal. Hydrogen generation has been also evaluated mainly by direct monitoring in the large-scale of vessel after the process. In this work, the revaluation of hydrogen generation was demonstrated on the basis of the open information of vessel, and the latest experimental data obtained in adsorption and radiolysis occurring in small-scale of zeolite-water mixtures. As a property of the zeolites (UOP IE-96, A-51), adsorption and desorption of water vapour on the zeolites were observed as a function of relative pressure corresponding to relative humidity. 10-20 wt% of water was found to be physically and chemically adsorbed on the zeolites within normal humidity of 20 to 90 %RH, reflecting residual water content absorbed on the dominant zeolites in the dewatering of vessels after the process. Hydrogen generated in the radiolysis of zeolite-water mixtures was further measured to obtain the observed yields of hydrogen as functions of water content in the mixtures and of the height of mixtures. It was found that additional water radiolysis took place through the energy dissipation of radiation to the zeolites, and that liquid depth effect on the yield in water was depressed by adding zeolites to water. Based on these experimental results and further estimations, hydrogen generation dependent on decay heat and water content in the SDS vessel was finally revaluated. The procedure and results in this revaluation would be helpful for the decontamination

  6. Stand alone solution for generation and storage of hydrogen and electric energy

    International Nuclear Information System (INIS)

    A novel method enabling safe, simple, and controllable production, storage, and use of hydrogen as well as compact electric energy storage and generation via hydrogen- oxygen fuel cells has been developed. The technology indicates, in our opinion, a significant milestone in the search for practical utilization of hydrogen as an alternative energy source. It consists of an original thermal-chemical treatment / activation of aluminum powders to react spontaneously with water to produce hydrogen at regular conditions according to the reaction Al+3H2O=Al (OH)3+3/2H2. Only about 1-2% of lithium, based activator is applied, and any type of water including tap water, sea water and waste water may be used, making the method attractive for variety of applications. 11% of hydrogen compared to the aluminum mass can be obtained, and our experiments reveal 90% reaction yield and more. The technology has a clear advantage over batteries, providing specific electric energy of over 2 kW h/kg Al, 5-10 times greater than that of commonly used lithium-ion batteries. Combined with a fuel cell it may be particularly beneficial for stand-alone electric power generators, where there is no access to the grid. Such applications include emergency generators (e.g., in hospitals), electricity backup systems, and power generation in remote communication posts. Automotive applications may be considered as well. The technology provides green electric energy and quiet operation as well as additional heat energy resulting mainly from the exothermic aluminum-water reaction. (full text)

  7. SLUDGE BATCH 4 FOLLOW-UP QUALIFICATION STUDIES TO EVALUATE HYDROGEN GENERATION

    Energy Technology Data Exchange (ETDEWEB)

    Pareizs, J; David Koopman, D; Dan Lambert, D; Cj Bannochie, C

    2007-08-23

    Follow-up testing was conducted to better understand the excessive hydrogen generation seen in the initial Sludge Batch 4 (SB4) qualification Sludge Receipt and Adjustment Tank/Slurry Mix Evaporator (SRAT/SME) simulation in the Savannah River National Laboratory (SRNL) Shielded Cells. This effort included both radioactive and simulant work. The initial SB4 qualification test produced 0.59 lbs/hr hydrogen in the SRAT, which was just below the DWPF SRAT limit of 0.65 lbs/hr, and the test produced over 0.5 lbs/hr hydrogen in the SME cycle on two separate occasions, which were over the DWPF SME limit of 0.223 lbs/hr.

  8. Generation of tubular beams of negative hydrogen ions by a surface plasma source

    International Nuclear Information System (INIS)

    The results of experiments on obtaining a tubular beam of hydrogen negative ions from a surface plasma source with emission ring slit of 100 mm diameter are described in the study. Conditions of burning of a high current ring discharge generating effectively hydrogen negative ions with current density up to 2.1 A/cm2 are investigated. The possibility of generation of intensive tubular beams of hydrogen negative ions by surface plasma sources is shown, the 2.4 A ion beam is obtained. The results of preliminary experiments on accelerating tubular beam up to 135 keV are described. Azymuthally uniform current density distribution of intensive tubular beams generated by discharges with a close electron drift in a surface plasma source with emission ring slit, absence of high-frequency oscillations in optimal conditions of sources operation as well as the possibility of the most complete use of generated by the discharge negative ions flow show the prospects of development of these sources for fast atom injectors

  9. In situ generation of hydrogen from water by aluminum corrosion in solutions of sodium aluminate

    Energy Technology Data Exchange (ETDEWEB)

    Soler, Lluis; Candela, Angelica Maria; Munoz, Maria; Casado, Juan [Centre Grup de Tecniques de Separacio en Quimica (GTS), Unitat de Quimica Analitica, Departament de Quimica, Universitat Autonoma de Barcelona, Campus UAB s/n, 08193 Bellaterra, Barcelona, Catalonia (Spain); Macanas, Jorge [Laboratoire de Genie Chimique, UMR 5503 CNRS-INPT-UPS, Universite de Toulouse, Toulouse (France)

    2009-07-01

    A new process to obtain hydrogen from water using aluminum in sodium aluminate solutions is described and compared with results obtained in aqueous sodium hydroxide. This process consumes only water and aluminum, which are raw materials much cheaper than other compounds used for in situ hydrogen generation, such as hydrocarbons and chemical hydrides, respectively. As a consequence, our process could be an economically feasible alternative for hydrogen to supply fuel cells. Results showed an improvement of the maximum rates and yields of hydrogen production when NaAlO{sub 2} was used instead of NaOH in aqueous solutions. Yields of 100% have been reached using NaAlO{sub 2} concentrations higher than 0.65 M and first order kinetics at concentrations below 0.75 M has been confirmed. Two different heterogeneous kinetic models are verified for NaAlO{sub 2} aqueous solutions. The activation energy (E{sub a}) of the process with NaAlO{sub 2} is 71 kJ mol{sup -1}, confirming a control by a chemical step. A mechanism unifying the behavior of Al corrosion in NaOH and NaAlO{sub 2} solutions is presented. The application of this process could reduce costs in power sources based on fuel cells that nowadays use hydrides as raw material for hydrogen production. (author)

  10. Modelling of thermal-hydraulics and hydrogen generation during quenching of a degraded core

    International Nuclear Information System (INIS)

    The hydrogen source from the reactor cooling system (RCS) is one of the most important boundary conditions for the containment. Thermal hydraulic analyses for the containment and accident management measures depend on the integral mass of generated hydrogen and on the hydrogen generation rate. This source term is strongly determined by the reactor type (PWR, VVER, BWR), the thermal power (size), and accident sequences. Quantitative assessments require careful analyses by means of computer code calculations and use of validated models. The quenching of a degraded core at high temperatures may result in high hydrogen generation in very short time as seen in the TMI-2 accident, the LOFT-LP-FP2 experiment and in the CORA and QUENCH test series. The realistic simulation of the core quenching requires the correct description of different conditions and processes: (1) the system pressure, (2) the amount of water delivered to the core or the flooding rate, (3) the sub-cooling of the water, (4) the temperature of the fuel rods and structure materials, (5) the configuration of the core materials or degree of core degradation, (6) the oxidation of cladding and grids, intact, molten or refrozen, and subsequently (7) the quench-front propagation and (8) stress cracking or spalling of cladding due to thermal shock. Besides these fundamental modelling requirements, some model details are briefly depicted. The interaction of these processes are discussed by means of analyses of the TMI-2 accident and of the test QUENCH-03 with ATHLET-CD1. Even though progress has been made in the simulation of oxidation during core reflooding, large uncertainties remain for a consistent description of thermal behaviour and hydrogen production. (authors)

  11. Generation of Hydrogen by Visible Light-Induced Water Splitting with the Use of Semiconductors and Dyes.

    Science.gov (United States)

    Rao, C N R; Lingampalli, Srinivasa Rao

    2016-01-01

    Photosynthesis that occurs in plants involves both the oxidation of water and the reduction of carbon dioxide. Plants carry out these reactions with ease, by involving electron-transport chains. In this article, hydrogen generation by the reduction of water in the laboratory by using semiconductor nanostructures through artificial photosynthesis is examined. Dye-sensitized photochemical generation of hydrogen from water is also discussed. Hydrogen generation by these means has great technological relevance, since it is an environmentally friendly fuel. The way in which oxygen can be generated by the oxidation of water using metal oxide catalysts is also shown. PMID:26425963

  12. Rapid hydrogen gas generation using reactive thermal decomposition of uranium hydride.

    Energy Technology Data Exchange (ETDEWEB)

    Kanouff, Michael P.; Van Blarigan, Peter; Robinson, David B.; Shugard, Andrew D.; Gharagozloo, Patricia E.; Buffleben, George M.; James, Scott Carlton; Mills, Bernice E.

    2011-09-01

    Oxygen gas injection has been studied as one method for rapidly generating hydrogen gas from a uranium hydride storage system. Small scale reactors, 2.9 g UH{sub 3}, were used to study the process experimentally. Complimentary numerical simulations were used to better characterize and understand the strongly coupled chemical and thermal transport processes controlling hydrogen gas liberation. The results indicate that UH{sub 3} and O{sub 2} are sufficiently reactive to enable a well designed system to release gram quantities of hydrogen in {approx} 2 seconds over a broad temperature range. The major system-design challenge appears to be heat management. In addition to the oxidation tests, H/D isotope exchange experiments were performed. The rate limiting step in the overall gas-to-particle exchange process was found to be hydrogen diffusion in the {approx}0.5 {mu}m hydride particles. The experiments generated a set of high quality experimental data; from which effective intra-particle diffusion coefficients can be inferred.

  13. Hydrogen generation from water using Mg nanopowder produced by arc plasma method

    International Nuclear Information System (INIS)

    We report that hydrogen gas can be easily produced from water at room temperature using a Mg nanopowder (30–1000 nm particles, average diameter 265 nm). The Mg nanopowder was produced by dc arc melting of a Mg ingot in a chamber with mixed-gas atmosphere (20% N2–80% Ar) at 0.1 MPa using custom-built nanopowder production equipment. The Mg nanopowder was passivated with a gas mixture of 1% O2 in Ar for 12 h in the final step of the synthesis, after which the nanopowder could be safely handled in ambient air. The nanopowder vigorously reacted with water at room temperature, producing 110 ml of hydrogen gas per 1 g of powder in 600 s. This amount corresponds to 11% of the hydrogen that could be generated by the stoichiometric reaction between Mg and water. Mg(OH)2 flakes formed on the surface of the Mg particles as a result of this reaction. They easily peeled off, and the generation of hydrogen continued until all the Mg was consumed.

  14. A polymer electrolyte fuel cell stack for stationary power generation from hydrogen fuel

    Energy Technology Data Exchange (ETDEWEB)

    Zawodzinski, C.; Wilson, M.; Gottesfeld, S. [Los Alamos National Lab., NM (United States)

    1996-10-01

    The fuel cell is the most efficient device for the conversion of hydrogen fuel to electric power. As such, the fuel cell represents a key element in efforts to demonstrate and implement hydrogen fuel utilization for electric power generation. A central objective of a LANL/Industry collaborative effort supported by the Hydrogen Program is to integrate PEM fuel cell and novel stack designs at LANL with stack technology of H-Power Corporation (H-Power) in order to develop a manufacturable, low-cost/high-performance hydrogen/air fuel cell stack for stationary generation of electric power. A LANL/H-Power CRADA includes Tasks ranging from exchange, testing and optimization of membrane-electrode assemblies of large areas, development and demonstration of manufacturable flow field, backing and bipolar plate components, and testing of stacks at the 3-5 cell level and, finally, at the 4-5 kW level. The stack should demonstrate the basic features of manufacturability, overall low cost and high energy conversion efficiency. Plans for future work are to continue the CRADA work along the time line defined in a two-year program, to continue the LANL activities of developing and testing stainless steel hardware for longer term stability including testing in a stack, and to further enhance air cathode performance to achieve higher energy conversion efficiencies as required for stationary power application.

  15. Hydrogen generation from water using Mg nanopowder produced by arc plasma method

    Directory of Open Access Journals (Sweden)

    Masahiro Uda, Hideo Okuyama, Tohru S Suzuki and Yoshio Sakka

    2012-01-01

    Full Text Available We report that hydrogen gas can be easily produced from water at room temperature using a Mg nanopowder (30–1000 nm particles, average diameter 265 nm. The Mg nanopowder was produced by dc arc melting of a Mg ingot in a chamber with mixed-gas atmosphere (20% N2–80% Ar at 0.1 MPa using custom-built nanopowder production equipment. The Mg nanopowder was passivated with a gas mixture of 1% O2 in Ar for 12 h in the final step of the synthesis, after which the nanopowder could be safely handled in ambient air. The nanopowder vigorously reacted with water at room temperature, producing 110 ml of hydrogen gas per 1 g of powder in 600 s. This amount corresponds to 11% of the hydrogen that could be generated by the stoichiometric reaction between Mg and water. Mg(OH2 flakes formed on the surface of the Mg particles as a result of this reaction. They easily peeled off, and the generation of hydrogen continued until all the Mg was consumed.

  16. Safety operation of chromatography column system with discharging hydrogen radiolytically generated

    Directory of Open Access Journals (Sweden)

    Watanabe Sou

    2015-01-01

    Full Text Available In the extraction chromatography system, accumulation of hydrogen gas in the chromatography column is suspected to lead to fire or explosion. In order to prevent the hazardous accidents, it is necessary to evaluate behaviors of gas radiolytically generated inside the column. In this study, behaviors of gas inside the extraction chromatography column were investigated through experiments and Computation Fluid Dynamics (CFD simulation. N2 gas once accumulated as bubbles in the packed bed was hardly discharged by the flow of mobile phase. However, the CFD simulation and X-ray imaging on γ-ray irradiated column revealed that during operation the hydrogen gas generated in the column was dissolved into the mobile phase without accumulation and discharged.

  17. Towards numerical simulation of turbulent hydrogen combustion based on flamelet generated manifolds in OpenFOAM

    Science.gov (United States)

    Fancello, A.; Bastiaans, R. J. M.; de Goey, L. P. H.

    2013-10-01

    This work proposes an application of the Flamelet-Generated Manifolds (FGM) technique in the OpenFOAM environment. FGM is a chemical reduced method for combustion modeling. This technique treats the combustion process as the solution of a small amount of controlling variables. Regarding laminar simulation, a progress variable and enthalpy evolution can describe satisfactorily the problem. From a turbulent point of view, FGM can be applied to LES and RANS simulations, where the subgrid chemical terms are described with a β - PDF approach. These approaches apply satisfactorily in relatively simple gases, nevertheless for hydrogen are not more valid, due to preferential diffusion effects and instability of the flame structure. The overall aim of this research is to find technical solution for hydrogen gas turbines design in the next generation of Integrated Gasification Combined Cycle (IGCC) plants.

  18. Photo-driven autonomous hydrogen generation system based on hierarchically shelled ZnO nanostructures

    International Nuclear Information System (INIS)

    A quantum dot semiconductor sensitized hierarchically shelled one-dimensional ZnO nanostructure has been applied as a quasi-artificial leaf for hydrogen generation. The optimized ZnO nanostructure consists of one dimensional nanowire as a core and two-dimensional nanosheet on the nanowire surface. Furthermore, the quantum dot semiconductors deposited on the ZnO nanostructures provide visible light harvesting properties. To realize the artificial leaf, we applied the ZnO based nanostructure as a photoelectrode with non-wired Z-scheme system. The demonstrated un-assisted photoelectrochemical system showed the hydrogen generation properties under 1 sun condition irradiation. In addition, the quantum dot modified photoelectrode showed 2 mA/cm2 current density at the un-assisted condition

  19. Double-side illuminated titania nanotubes for high volume hydrogen generation by water splitting

    International Nuclear Information System (INIS)

    A sonoelectrochemical anodization method is proposed to synthesize TiO2 nanotubular arrays on both sides of a titanium foil (TiO2/Ti/TiO2). Highly ordered TiO2 nanotubular arrays of 16 cm2 area with uniform surface distribution can be obtained using this anodization procedure. These double-sided TiO2/Ti/TiO2 materials are used as both photoanode (carbon-doped titania nanotubes) and cathode (Pt nanoparticles dispersed on TiO2 nanotubes; PtTiO2/Ti/PtTiO2) in a specially designed photoelectrochemical cell to generate hydrogen by water splitting at a rate of 38 ml h-1. The nanomaterials are characterized by FESEM, HRTEM, STEM, EDS, FFT, SAED and XPS techniques. The present approach can be used for large-scale hydrogen generation using renewable energy sources

  20. Graphene sheets/cobalt nanocomposites as low-cost/high-performance catalysts for hydrogen generation

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Fei; Hou, Chengyi; Zhang, Qinghong [State Key Laboratory for Modification of Chemical Fibers and Polymer Materials, Donghua University, Shanghai 201620 (China); Wang, Hongzhi, E-mail: wanghz@dhu.edu.cn [State Key Laboratory for Modification of Chemical Fibers and Polymer Materials, Donghua University, Shanghai 201620 (China); Li, Yaogang, E-mail: yaogang_li@dhu.edu.cn [College of Materials Science and Engineering, Donghua University, Shanghai 201620 (China)

    2012-08-15

    The production of clean and renewable hydrogen through the hydrolysis of sodium borohydride has received much attention owing to increasing global energy demands. Graphene sheets/cobalt (GRs/Co) nanocomposites, which are highly efficient catalysts, have been prepared using a one-step solvothermal method in ethylene glycol. Co{sup 2+} salts were converted to Co nanoparticles, which were simultaneously inserted into the graphene layers with the reduction of graphite oxide sheets to GRs. The as-synthesized samples were characterized by X-ray diffraction, Fourier transform infrared spectra, Raman spectroscopy, field emission scanning electron microscopy, transmission electron microscopy, high-resolution transmission electron microscopy and vibrating sample magnetometer. The maximum saturation magnetization value reached 80.8 emu g{sup -1}, meaning they are more suitable for magnet-controlled generation of H{sub 2} than noble metal catalysts. The catalytic activity of the composite was investigated by the hydrolysis of sodium borohydride in aqueous solution both with and without a GRs support. It was found that the high electronic conductive GRs support increased the hydrogen generation rate (about two times) compared with pure cobalt. The improved hydrogen generation rate, low cost and uncomplicated recycling makes the GRs/Co nanocomposites promising candidates as catalysts for hydrogen generation. Highlights: Black-Right-Pointing-Pointer Graphene sheets/cobalt nanocomposites were prepared by a one-step solvothermal method. Black-Right-Pointing-Pointer The maximum saturation magnetization value of the composites reached 80.8 emu g{sup -1}. Black-Right-Pointing-Pointer The graphene support greatly increased the catalytic activity of cobalt. Black-Right-Pointing-Pointer An easily removed, recycled and controlled functional filter was obtained.

  1. Tungsten dust nanoparticles generation from blistering bursts under hydrogen environment in microwave ECR discharge

    Science.gov (United States)

    Ouaras, K.; Hassouni, K.; Delacqua, L. Colina; Lombardi, G.; Vrel, D.; Bonnin, X.

    2015-11-01

    Blistering burst induced tungsten dust nanoparticles were observed for the first time when a tungsten sample is submitted to a hydrogen low-temperature discharge under low flux and low incident energy values (20, 120 and 220 eV) at a surface temperature of 500 K. Tungsten nanoparticles (˜50 nm) were organized in 2D domains with diameter that is well correlated to the blister volume losses by burst. These observations suggest that dust nanoparticles were generated from blistering burst.

  2. Optimization of electricity / hydrogen cogeneration from generation IV nuclear energy systems

    OpenAIRE

    Gomez, Adrien; Azzaro-Pantel, Catherine; Pibouleau, Luc; Domenech, Serge; Latgé, Christian; Dumaz, Patrick; Haubensack, David

    2007-01-01

    One of the great motivations of studying and developing Generation IV (Gen IV) reactors of VHTR (Very High Temperature Reactor) design concept is their capacity to efficiently produce both electricity and H2 (hydrogen). This study aims at developing an optimization methodology for cogeneration systems of H2 and electricity, from Gen IV nuclear reactors, with respect to energy constraints, economics and conjuncture in term of demand. It lies within a scope of a collaboration between the Labora...

  3. A molecular molybdenum–schiff base electro-catalyst for generating hydrogen from acetic acid or water

    International Nuclear Information System (INIS)

    Highlights: • The reaction of ligand, H2L and MoCl5 gives a Mo(VI) complex [MoL(O)2] 1. • Complex 1 is capable of catalyzing hydrogen evolution from acetic acid and water. • TOF reaches a maximum of 68 (DMF) and 356 (buffer, pH 6) moles/h, respectively. • Sustained proton reduction catalysis occurs over a 69 h period and no decomposition of 1. - ABSTRACT: The reaction of 2-pyridylamino-N,N-bis(2-methylene-4-ethyl-6-tert-butylphenol) (H2L) and MoCl5 gives a molybdenum(VI) complex [MoL(O)2] 1, a new molecular electrocatalyst, which has been determined by X-ray crystallography. Electrochemical studies show that complex 1 can catalyze hydrogen evolution from acetic acid or aqueous buffer. Turnover frequency (TOF) reaches a maximum of 68 (in N,N-Dimethylformamide (DMF)) and 356 (in buffer, pH 6.0) moles of hydrogen per mole of catalyst per hour, respectively. Sustained proton reduction catalysis occurs at glassy carbon (GC) electrode to give H2 over a 69 h electrolysis period and no observable decomposition of the catalyst

  4. Hydrogen generation by photoelectrochemical effect of the Cu-doped TiO2 photoanode

    International Nuclear Information System (INIS)

    TiO2 film photoanodes with a size of 1 × 1 cm2 were fabricated by a spin coating method. Cu-doped TiO2 powder with various Cu concentrations (0.2, 0.4, 0.6 and 0.8 at%) and surfactant were used as starting materials in coating Cu-doped TiO2 thin films onto FTO/glass substrate. Crystalline structure of TiO2 material, microstructure of the photoanode films and their thickness were identified by x-ray diffraction and Raman scattering. Hydrogen generation from water by photoelectrochemical effect in the visible light was observed by recording I/V characteristics of the photoanode in dark and light regimes. The obtained results have shown that the hydrogen generation efficiency of photoanode nonlinearly depends on Cu concentration. The nonlinear dependence of the hydrogen generation efficiency may be due to a change of resistivity of the film photoanode that is related with the random distribution of the hetero-junction between interfaces of TiO2 and CuO nanoparticles. (paper)

  5. Probing the antibody-catalyzed water-oxidation pathway at atomic resolution

    OpenAIRE

    Zhu, Xueyong; Wentworth, Paul; Wentworth, Anita D.; Eschenmoser, Albert; Lerner, Richard A.; Wilson, Ian A.

    2004-01-01

    Antibodies can catalyze the generation of hydrogen peroxide (H2O2) from singlet dioxygen (1O*2) and water via the postulated intermediacy of dihydrogen trioxide (H2O3) and other trioxygen species. Nine different crystal structures were determined to elucidate the chemical consequences to the antibody molecule itself of exposure to such reactive intermediates and to provide insights into the location on the antibody where these species could be generated. Herein, we report structural evidence ...

  6. Mixed Ionic and Electonic Conductors for Hydrogen Generation and Separation: A New Approach

    Energy Technology Data Exchange (ETDEWEB)

    Srikanth Gopalan

    2006-12-31

    Composite mixed conductors comprising one electronic conducting phase, and one ionic conducting phase (MIECs) have been developed in this work. Such MIECs have applications in generating and separating hydrogen from hydrocarbon fuels at high process rates and high purities. The ionic conducting phase comprises of rare-earth doped ceria and the electronic conducting phase of rare-earth doped strontium titanate. These compositions are ideally suited for the hydrogen separation application. In the process studied in this project, steam at high temperatures is fed to one side of the MIEC membrane and hydrocarbon fuel or reformed hydrocarbon fuel to the other side of the membrane. Oxygen is transported from the steam side to the fuel side down the electrochemical potential gradient thereby enriching the steam side flow in hydrogen. The remnant water vapor can then be condensed to obtain high purity hydrogen. In this work we have shown that two-phase MIECs comprising rare-earth ceria as the ionic conductor and doped-strontium titanate as the electronic conductor are stable in the operating environment of the MIEC. Further, no adverse reaction products are formed when these phases are in contact at elevated temperatures. The composite MIECs have been characterized using a transient electrical conductivity relaxation technique to measure the oxygen chemical diffusivity and the surface exchange coefficient. Oxygen permeation and hydrogen generation rates have been measured under a range of process conditions and the results have been fit to a model which incorporates the oxygen chemical diffusivity and the surface exchange coefficient from the transient measurements.

  7. Thermodynamic analysis of hydrogen rich synthetic gas generation from fluidized bed gasification of rice husk

    International Nuclear Information System (INIS)

    In the present work, the generation of hydrogen rich synthetic gas from fluidized bed steam gasification of rice husk has been studied. An equilibrium model based on equilibrium constant and material balance has been developed to predict the gas compositions. The equilibrium gas compositions are compared with the experimental data of the present group as well as of available literature. The energy and exergy analysis of the process have been carried out by varying steam to biomass ratio (ψ) within the range between 0.1-1.5 and gasification temperature from 600 oC to 900 oC. It is observed that both the energy and exergy efficiencies are maximum at the CBP (carbon boundary point) though the hydrogen production increases beyond the CBP. The HHV (higher heating value) and the external energy input both continuously increase with ψ. However, the hydrogen production initially increases with increase in temperature up to 800 oC and then becomes nearly asymptotic. The HHV decreases rapidly with increase in temperature and energy input increases. Therefore, gasification in lower temperature region is observed to be economical in terms of a trade off between external energy input and HHV of the product gas. -- Highlights: → Energy and exergy analysis of hydrogen rich synthetic gas generation from fluidized bed steam gasification of rice husk. → Effect of steam-to-biomass ration and gasification temperature is studied. → Maximum efficiencies occur at the (CBP) carbon boundary point though the hydrogen production increases beyond CBP. → Gasification in lower temperature region is observed to be optimum.

  8. Hydrogen gas generation from refuse-derived fuel (RDF) under wet conditions.

    Science.gov (United States)

    Sakka, Makiko; Kimura, Tetsuya; Sakka, Kazuo; Ohmiya, Kunio

    2004-02-01

    An explosion has recently occurred at a silo containing refuse-derived fuels (RDF) in Japan. There is a possibility that microorganisms are involved in generation of combustible gas from RDF and this study was aimed at showing the presence of bacteria that can ferment RDF pellets. All RDF samples tested contained a relatively high number of viable bacterial cells, 1.4x10(5) to 3.2x10(6) viable cells/g. These bacteria in the RDF samples fermented them to generate heat and hydrogen gas. PMID:14981319

  9. Generation of Hydrogen, Lignin and Sodium Hydroxide from Pulping Black Liquor by Electrolysis

    OpenAIRE

    Guangzai Nong; Zongwen Zhou; Shuangfei Wang

    2015-01-01

    Black liquor is generated in Kraft pulping of wood or non-wood raw material in pulp mills, and regarded as a renewable resource. The objective of this paper was to develop an effective means to remove the water pollutants by recovery of both lignin and sodium hydroxide from black liquor, based on electrolysis. The treatment of a 1000 mL of black liquor (122 g/L solid contents) consumed 345.6 kJ of electric energy, and led to the generation of 30.7 g of sodium hydroxide, 0.82 g of hydrogen gas...

  10. Investigation of the high-order harmonic generation and ionization of model hydrogen atom and real hydrogen atom in intense laser field

    International Nuclear Information System (INIS)

    Solving time-dependent Schroedinger equation numerically, we investigate the high-order harmonic generation and ionization probability of one dimensional, two dimensional and three dimensional hydrogen atom exposed to intense laser field. In the tunneling ionization regime, our results show that the HHG plateau features and cutoff positions of model hydrogen atoms are well agreement with those of real hydrogen atom, and the trend of changing of the ionization probabilities with time is similar, but the values of ionization probabilities for model atoms are different from ones for three dimensional hydrogen atom. We explain the reason for the difference of ionization probabilities between model atoms and real hydrogen atom according to the semiclassical three-step model. (author)

  11. Multi-Generation Concentrating Solar-Hydrogen Power System for Sustainable Rural Development

    Energy Technology Data Exchange (ETDEWEB)

    Krothapalli, A.; Greska, B.

    2007-07-01

    This paper describes an energy system that is designed to meet the demands of rural populations that currently have no access to grid-connected electricity. Besides electricity, it is well recognized that rural populations need at least a centralized refrigeration system for storage of medicines and other emergency supplies, as well as safe drinking water. Here we propose a district system that will employ a multi-generation concentrated solar power (CSP) system that will generate electricity and supply the heat needed for both absorption refrigeration and membrane distillation (MD) water purification. The electricity will be used to generate hydrogen through highly efficient water electrolysis and individual households can use the hydrogen for generating electricity, via affordable proton exchange membrane (PEM) fuel cells, and as a fuel for cooking. The multi-generation system is being developed such that its components will be easy to manufacture and maintain. As a result, these components will be less efficient than their typical counterparts but their low cost-to-efficiency ratio will allow for us to meet our installation cost goal of $1/Watt for the entire system. The objective of this paper is to introduce the system concept and discuss the system components that are currently under development. (auth)

  12. Broadband, stable and highly coherent supercontinuum generation at telecommunication wavelengths in an hydrogenated amorphous silicon waveguide

    CERN Document Server

    Leo, F; Kuyken, B; Roelkens, G; Gorza, S -P

    2014-01-01

    Hydrogenated amorphous silicon (a:Si-H) has recently been recognized as a highly nonlinear CMOS compatible photonic platform. We experimentally demonstrate the generation of a supercontinuum (SC) spanning over 500 nm in a-Si:H photonic wire waveguide at telecommunication wavelengths using femtosecond input pulse with energy lower than 5 pJ. Numerical modeling of pulse propagation in the waveguide, based on the experimentally characterized dispersion profile, shows that the supercontinuum is the result of soliton fission and dispersive wave generation. It is demonstrated that the SC is highly coherent and that the waveguides do not suffer from material degradation under femtosecond pulse illumination. Finally, a direct comparison of SC generation in c-Si and a-Si:H waveguides confirms the higher performances of a-Si:H over c-Si for broadband low power SC generation at telecommunication wavelengths.

  13. Hydrogen Generation Through Renewable Energy Sources at the NASA Glenn Research Center

    Science.gov (United States)

    Colozza, Anthony; Prokopius, Kevin

    2007-01-01

    An evaluation of the potential for generating high pressure, high purity hydrogen at the NASA Glenn Research Center (GRC) was performed. This evaluation was based on producing hydrogen utilizing a prototype Hamilton Standard electrolyzer that is capable of producing hydrogen at 3000 psi. The present state of the electrolyzer system was determined to identify the refurbishment requirements. The power for operating the electrolyzer would be produced through renewable power sources. Both wind and solar were considered in the analysis. The solar power production capability was based on the existing solar array field located at NASA GRC. The refurbishment and upgrade potential of the array field was determined and the array output was analyzed with various levels of upgrades throughout the year. The total available monthly and yearly energy from the array was determined. A wind turbine was also sized for operation. This sizing evaluated the wind potential at the site and produced an operational design point for the wind turbine. Commercially available wind turbines were evaluated to determine their applicability to this site. The system installation and power integration were also addressed. This included items such as housing the electrolyzer, power management, water supply, gas storage, cooling and hydrogen dispensing.

  14. Simultaneous Hydrogen Generation and Waste Acid Neutralization in a Reverse Electrodialysis System

    KAUST Repository

    Hatzell, Marta C.

    2014-09-02

    Waste acid streams produced at industrial sites are often co-located with large sources of waste heat (e.g., industrial exhaust gases, cooling water, and heated equipment). Reverse electrodialysis (RED) systems can be used to generate electrical power and hydrogen gas using waste heat-derived solutions, but high electrode overpotentials limit system performance. We show here that an ammonium bicarbonate (AmB) RED system can achieve simultaneous waste acid neutralization and in situ hydrogen production, while capturing energy from excess waste heat. The rate of acid neutralization was dependent on stack flow rate and increased 50× (from 0.06 ± 0.04 to 3.0 ± 0.32 pH units min -1 m-2 membrane), as the flow rate increased 6× (from 100 to 600 mL min-1). Acid neutralization primarily took place due to ammonium electromigration (37 ± 4%) and proton diffusion (60 ± 5%). The use of a synthetic waste acid stream as a catholyte (pH ≈ 2) also increased hydrogen production rates by 65% (from 5.3 ± 0.5 to 8.7 ± 0.1 m3 H2 m-3 catholyte day -1) compared to an AmB electrolyte (pH ≈ 8.5). These findings highlight the potential use of dissimilar electrolytes (e.g., basic anolyte and acidic catholyte) for enhanced power and hydrogen production in RED stacks. © 2014 American Chemical Society.

  15. Oxidation and reduction of copper and iron species in steam generator deposits - Effects of hydrazine, carbohydrazide and catalyzed hydrazine

    International Nuclear Information System (INIS)

    It has long been suspected that oxidation and reduction of secondary side deposits in PWR steam generators have a significant influence on the onset of intergranular attack and stress corrosion cracking (IGA/SCC) of mill annealed Alloy 600 steam generator tubes. It is believed that these same processes could affect the possible future occurrence of IGA/SCC of thermally treated Alloy 600 and Alloy 690 tubes that are in newer steam generators. The working hypothesis for describing the influence of oxides on accelerated tube degradation is that deposits formed during normal operation are oxidized during lay-up. During subsequent operation, these oxidized species accelerate tube degradation by raising the electrochemical potential. (authors)

  16. Research progress of olefins asymmetric hydrogenation catalyzed by rhodium catalysts%铑催化剂催化烯烃不对称加氢反应研究进展

    Institute of Scientific and Technical Information of China (English)

    王红琴; 蒋丽红; 王亚明

    2016-01-01

    不对称催化氢化反应具有完美的原子经济性和清洁高效等特点,是最受青睐的不对称合成方法之一。C=C、C=O、C=N 的不对称加氢反应仍主要依赖过渡金属催化剂。过渡金属催化剂,尤其是铑催化剂,催化碳碳双键的不对称加氢反应仍是一个不断发展的领域。本文对近年来利用铑催化剂催化烯烃进行不对称氢化反应的研究进展进行了综述,着重介绍了铑-双膦配体催化体系催化烯烃不对称加氢反应的催化机理,以及铑催化剂在烯胺、不饱和羧酸及衍生物、烯醇酯和非官能团烯烃不对称氢化中的应用,并通过对现有文献的总结指出了今后铑催化剂催化烯烃氢化反应的研究重点,即:①铑-单膦配体催化烯烃不对称氢化反应的作用机理须待提出;②非官能化底物不对称催化氢化反应的手性配体亟待拓宽。%Asymmetric hydrogenation has the advantage of cleanliness,perfect atom economy,and is one of the hottest methods of asymmetric synthesis. The asymmetric hydrogenation in C=C,C=O, C=N are still primarily dependent on the use of transition metal catalysts. The study of transition metal catalysts,especially the asymmetric hydrogenation of carbon-carbon double bond catalyzed by rhodium catalysts is still an evolving field. In the present review,the progress on asymmetric hydrogenation of olefins catalyzed by rhodium catalysts are described,including the catalytic mechanism of rhodium-diphosphine ligand catalyst system,the application of asymmetric hydrogenation of enamines,unsaturated carboxylic acids and their derivatives,enol ester as well as unfunctionalized olefins catalyzed by rhodium catalysts. The development trend of rhodium catalysts for asymmetric hydrogenation of olefins was pointed out. For instance:① the catalytic mechanism of asymmetric hydrogenation of olefins by rhodium-monophosphine ligand needs to be understood;②more chiral ligands for

  17. Methanolysis of ammonia borane by shape-controlled mesoporous copper nanostructures for hydrogen generation.

    Science.gov (United States)

    Yao, Qilu; Huang, Ming; Lu, Zhang-Hui; Yang, Yuwen; Zhang, Yuxin; Chen, Xiangshu; Yang, Zhen

    2015-01-21

    Diverse mesoporous CuO nanostructures have been prepared by a facile and scaleable wet-chemical method and reduced to mesoporous Cu nanostructures by using the reductant ammonia borane (AB). These mesoporous Cu nanostructures have been applied as a catalyst for hydrogen generation from the methanolysis of AB. The catalytic results show that the reaction rate and the amount of hydrogen evolution significantly relied on their morphologies. Compared with the nanosheet-like, bundle-like and dandelion-like Cu, the flower-like Cu nanostructures exhibit the highest catalytic activity with a total turnover frequency (TOF) value of 2.41 mol H2 mol catalyst(-1) min(-1) and a low activation energy value of 34.2 ± 1.2 kJ mol(-1) at room temperature. Furthermore, the flower-like Cu nanostructures have also shown excellent activity in recycling tests. The low cost and high performance of Cu nanocatalysts may offer high potential for its practical application in hydrogen generation from the methanolysis of AB. PMID:25409979

  18. Development of reversible solid oxide fuel cell for power generation and hydrogen production

    Science.gov (United States)

    Jung, G. B.; Chen, J. Y.; Lin, C. Y.; Chan, S. H.

    2011-06-01

    A reversible solid oxide fuel cell (RSOFC) provides the dual function of performing energy storage and power generation, all in one unit. When functioning as an energy storage device, the RSOFC acts like an electrolyzer in water electrolysis mode; whereby the electric energy is stored as (electrolyzed) hydrogen and oxygen gases. While hydrogen is useful as a transportation fuel and in other industrial applications, the RSOFC also acts as a fuel cell in power generation mode to produce electricity when needed. The RSOFC would be a competitive technology in the upcoming hydrogen economy on the basis of its low cost, simple structure, and high efficiency. This paper reports on the design and manufacturing of its membrane electrode assembly using commercially available materials. Also reported are the resulting performance, both in electrolysis and fuel cell modes, as a function of its operating parameters such as temperature and current density. We found that the RSOFC performance improved with increasing temperature and its fuel cell mode had a better performance than its electrolysis mode due to a limited humidity inlet causing concentration polarization.

  19. Evaluation of two processes of hydrogen production starting from energy generated by high temperature nuclear reactors

    International Nuclear Information System (INIS)

    In this work an evaluation to two processes of hydrogen production using energy generated starting from high temperature nuclear reactors (HTGR's) was realized. The evaluated processes are the electrolysis of high temperature and the thermo-chemistry cycle Iodine-Sulfur. The electrolysis of high temperature, contrary to the conventional electrolysis, allows reaching efficiencies of up to 60% because when increasing the temperature of the water, giving thermal energy, diminishes the electric power demand required to separate the molecule of the water. However, to obtain these efficiencies is necessary to have water vapor overheated to more than 850 grades C, temperatures that can be reached by the HTGR. On the other hand the thermo-chemistry cycle Iodine-Sulfur, developed by General Atomics in the 1970 decade, requires two thermal levels basically, the great of them to 850 grades C for decomposition of H2SO4 and another minor to 360 grades C approximately for decomposition of H I, a high temperature nuclear reactor can give the thermal energy required for the process whose products would be only hydrogen and oxygen. In this work these two processes are described, complete models are developed and analyzed thermodynamically that allow to couple each hydrogen generation process to a reactor HTGR that will be implemented later on for their dynamic simulation. The obtained results are presented in form of comparative data table of each process, and with them the obtained net efficiencies. (author)

  20. Performance of laboratory polymer electrolyte membrane hydrogen generator with sputtered iridium oxide anode

    Science.gov (United States)

    Labou, D.; Slavcheva, E.; Schnakenberg, U.; Neophytides, S.

    The continuous improvement of the anode materials constitutes a major challenge for the future commercial use of polymer electrolyte membranes (PEM) electrolyzers for hydrogen production. In accordance to this direction, iridium/titanium films deposited directly on carbon substrates via magnetron sputtering are operated as electrodes for the oxygen evolution reaction interfaced with Nafion 115 electrolyte in a laboratory single cell PEM hydrogen generator. The anode with 0.2 mg cm -2 Ir catalyst loading was electrochemically activated by cycling its potential value between 0 and 1.2 V (vs. RHE). The water electrolysis cell was operated at 90 °C with current density 1 A cm -2 at 1.51 V without the ohmic contribution. The corresponding current density per mgr of Ir catalyst is 5 A mg -1. The achieved high efficiency is combined with sufficient electrode stability since the oxidation of the carbon substrate during the anodic polarization is almost negligible.

  1. Molecular molybdenum persulfide and related catalysts for generating hydrogen from water

    Energy Technology Data Exchange (ETDEWEB)

    Long, Jeffrey R.; Chang, Christopher J.; Karunadasa, Hemamala I.; Majda, Marcin

    2016-04-19

    New metal persulfido compositions of matter are described. In one embodiment the metal is molybdenum and the metal persulfido complex mimics the structure and function of the triangular active edge site fragments of MoS.sub.2, a material that is the current industry standard for petroleum hydro desulfurization, as well as a promising low-cost alternative to platinum for electrocatalytic hydrogen production. This molecular [(PY5W.sub.2)MoS.sub.2].sup.x+ containing catalyst is capable of generating hydrogen from acidic-buffered water or even seawater at very low overpotentials at a turnover frequency rate in excess of 500 moles H.sub.2 per mole catalyst per second, with a turnover number (over a 20 hour period) of at least 19,000,000 moles H.sub.2 per mole of catalyst.

  2. Mitigation of Hydrogen Gas Generation from the Reaction of Water with Uranium Metal in K Basins Sludge

    Energy Technology Data Exchange (ETDEWEB)

    Sinkov, Sergey I.; Delegard, Calvin H.; Schmidt, Andrew J.

    2010-01-29

    Means to decrease the rate of hydrogen gas generation from the chemical reaction of uranium metal with water were identified by surveying the technical literature. The underlying chemistry and potential side reactions were explored by conducting 61 principal experiments. Several methods achieved significant hydrogen gas generation rate mitigation. Gas-generating side reactions from interactions of organics or sludge constituents with mitigating agents were observed. Further testing is recommended to develop deeper knowledge of the underlying chemistry and to advance the technology aturation level. Uranium metal reacts with water in K Basin sludge to form uranium hydride (UH3), uranium dioxide or uraninite (UO2), and diatomic hydrogen (H2). Mechanistic studies show that hydrogen radicals (H·) and UH3 serve as intermediates in the reaction of uranium metal with water to produce H2 and UO2. Because H2 is flammable, its release into the gas phase above K Basin sludge during sludge storage, processing, immobilization, shipment, and disposal is a concern to the safety of those operations. Findings from the technical literature and from experimental investigations with simple chemical systems (including uranium metal in water), in the presence of individual sludge simulant components, with complete sludge simulants, and with actual K Basin sludge are presented in this report. Based on the literature review and intermediate lab test results, sodium nitrate, sodium nitrite, Nochar Acid Bond N960, disodium hydrogen phosphate, and hexavalent uranium [U(VI)] were tested for their effects in decreasing the rate of hydrogen generation from the reaction of uranium metal with water. Nitrate and nitrite each were effective, decreasing hydrogen generation rates in actual sludge by factors of about 100 to 1000 when used at 0.5 molar (M) concentrations. Higher attenuation factors were achieved in tests with aqueous solutions alone. Nochar N960, a water sorbent, decreased hydrogen

  3. Ring Expansion of Cyclic 1,2-Diols to form Medium Sized Rings via Ruthenium Catalyzed Transfer Hydrogenative [4+2] Cycloaddition

    OpenAIRE

    Kasun, Zachary A.; Geary, Laina M.; Krische, Michael J.

    2014-01-01

    A new method for the ring expansion of cyclic diols is described. Using improved conditions for the ruthenium(0) catalyzed cycloaddition of cyclic 1,2-diols with 1,3-dienes, fused [n.4.0] bicycles 3a–3r (n = 3–6) are formed, which upon exposure to iodosobenzene diacetate engage in oxidative cleavage to form the 9–12 membered rings 4a–4r.

  4. Experimental Study of Plasma Under-liquid Electrolysis in Hydrogen Generation

    Institute of Scientific and Technical Information of China (English)

    严宗诚; 陈砺; 王红林

    2006-01-01

    The application and characteristics of relatively big volume plasma produced with cathodic glow discharges taking place across a gaseous envelope over the cathode which was dipped into electrolyte in hydrogen generation were studied. A critical investigation of the influence of methanol concentration and voltage across the circuit on the composition and power consumption per cubic meter of cathode liberating gas was carried out. The course of plasma under-liquid electrolysis has the typical characteristics of glow discharge electrolysis. The cathode liberating gas was in substantial excess of the Faraday law value. When the voltage across the circuit was equal to 550 V, the volume of cathodic gas with sodium carbonate solution was equal to 16.97 times the Faraday law value. The study showed that methanol molecules are more active than water molecules.The methanol molecules were decomposed at the plasma-catholyte interface by the radicals coming out the plasma mantle.Energy consumption per cubic meter of cathodic gases (WV) decreased while methanol concentration of the electrolytes increased. When methanol concentration equaled 5% (ψ), WV was 10.381×103 kJ/m3, less than the corresponding theoretic value of conventional water electrolysis method. The cathodic liberating gas was a mixture of hydrogen, carbon dioxide and carbon monoxide with over 95% hydrogen, if methanol concentration was more than 15% (ψ). The present research work revealed an innovative application of glow discharge and a new highly efficient hydrogen generation method, which depleted less resource and energy than normal electrolysis and is environmentally friendly.

  5. An assessment of hydrogen generation for the PBF severe fuel damage scoping and 1-1 tests

    International Nuclear Information System (INIS)

    An evaluation of zircaloy oxidation and hydrogen generation data is presented for the first two Severe Fuel Damage (SFG) tests, conducted in the Power Burst Facility at the Idaho National Engineering Laboratory. This work is in support of an internationally sponsored severe accident research program, initiated by the US Nuclear Regulatory Commission to advance the understanding and methodology for predicting light water reactor core degradation, hydrogen generation, and fission product behavior during severe accidents. The principal objective of this report is an assessment of in-vessel hydrogen generation issues using data provided by the SFD Scoping Test (SFD-ST) and SFD 1-1 test. The principal issues in question are the influence of zircaloy melting on oxidation behavior and fuel bundle reconfiguration effects which may alter steam flow and hydrogen generation characteristics. 41 refs., 42 figs., 11 tabs

  6. Transient modelling of sulphur-iodine cycle thermochemical hydrogen generation coupled to pebble bed modular reactor

    International Nuclear Information System (INIS)

    A transient control volume model of the sulphur iodine (S-I) and Westinghouse hybrid sulphur (HyS) cycles is presented. These cycles are some of the leading candidates for hydrogen generation using a high temperature heat source. The control volume models presented here are based on a heat and mass balance in each reaction chamber coupled to the relevant reaction kinetics. The chemical kinetics expressions are extracted from a relevant literature review. Two assumptions regarding reaction chamber pressure are identified, namely a constant pressure condition and a differential form of ideal gas law. The HyS model is based on an application of the Nernst equation. This application of the Nernst equation suggests that in the HyS cycle the hydrogen generation rate is directly proportional to the SO2 production rate. The observed chemical kinetic response time of the sulphuric acid decomposition section is on the order of 30 seconds, whereas the response time of the hydrogen iodide decomposition section is on the order of 500 seconds. It is concluded that the decomposition of hydrogen iodide (HI) is the rate limiting step of the entire S-I cycle. High temperature nuclear reactors are ideal candidates for use as a driving heat source for both the S-I and HyS cycle. The pebble bed modular reactor is a type of very high temperature reactor (VHTR ) suitable for nuclear hydrogen generation. A methodology for coupling of the S-I or HyS cycle to a pebble bed modular reactor (PBMR) via an intermediate heat exchanger (IHX) is developed. A 2-D THERMIX heat transfer model of a PBMR-268 is presented, and this model is coupled to a point kinetics model. The point kinetics model was developed to meet the same specifications as the RELAP5 point kinetics module. A steady-state integration of the S-I and HyS cycle models to the PBMR 268 heat transfer model is performed. The integration assumes that 100% of the heat energy from the PBMR-268 is deposited into the chemical plant via the

  7. Classical Dynamics of Harmonic Generation of the Hydrogen Molecular Ion Interacting with Ultrashort Intense Laser Pulses

    Institute of Scientific and Technical Information of China (English)

    LI Chao-Hong; DUAN Yi-Wu; Wing-Ki Liu; Jian-Min Yuan

    2001-01-01

    Within Born-Oppenheimer approximation, by using the classical trajectory theory, a description for the high order harmonic generation of the hydrogen molecular ion interacting with ultrashort laser pulses has been pre sented. The Coulomb singularities have been remedied by the regularization. The action-angle variables have been used to generate the initial inversion symmetry microcanonical distribution. Within a proper intensity range, a harmonic plateau with only odd harmonics appears. For a larger intensity, because of the existence of chaos, the harmonic spectra become noisier. For a large enough intensity, the ionization takes place and the harmonics disappear. So the chaos causes the noises, the ionization suppresses the harmonic generation, and the onset of the ionization follows the onset of chaos.

  8. Hydrogen sulfide generation in simulated construction and demolition debris landfills: impact of waste composition.

    Science.gov (United States)

    Yang, Kenton; Xu, Qiyong; Townsend, Timothy G; Chadik, Paul; Bitton, Gabriel; Booth, Matthew

    2006-08-01

    Hydrogen sulfide (H2S) generation in construction and demolition (C&D) debris landfills has been associated with the biodegradation of gypsum drywall. Laboratory research was conducted to observe H2S generation when drywall was codisposed with different C&D debris constituents. Two experiments were conducted using simulated landfill columns. Experiment 1 consisted of various combinations of drywall, wood, and concrete to determine the impact of different waste constituents and combinations on H2S generation. Experiment 2 was designed to examine the effect of concrete on H2S generation and migration. The results indicate that decaying drywall, even alone, leached enough sulfate ions and organic matter for sulfate-reducing bacteria (SRB) to generate large H2S concentrations as high as 63,000 ppmv. The codisposed wastes show some effect on H2S generation. At the end of experiment 1, the wood/drywall and drywall alone columns possessed H2S concentrations > 40,000 ppmv. Conversely, H2S concentrations were < 1 ppmv in those columns containing concrete. Concrete plays a role in decreasing H2S by increasing pH out of the range for SRB growth and by reacting with H2S. This study also showed that wood lowered H2S concentrations initially by decreasing leachate pH values. Based on the results, two possible control mechanisms to mitigate H2S generation in C&D debris landfills are suggested. PMID:16933645

  9. Improvement of the efficiency of a space oxygen-hydrogen electrochemical generator

    Science.gov (United States)

    Glukhikh, I. N.; Shcherbakov, A. N.; Chelyaev, V. F.

    2014-12-01

    This paper describes the method used for cooling of an on-board oxygen-hydrogen electrochemical generator (ECG). Apart from electric power, such a unit produces water of reaction and heat; the latter is an additional load on the thermal control system of a space vehicle. This load is undesirable in long-duration space flights, when specific energy characteristics of on-board systems are the determining factors. It is suggested to partially compensate the energy consumption by the thermal control system of a space vehicle required for cooling of the electrochemical generator through evaporation of water of reaction from the generator into a vacuum (or through ice sublimation if the pressure in the ambient space is lower than that in the triple point of water.) Such method of cooling of an electrochemical generator improves specific energy parameters of an on-board electric power supply system, and, due to the presence of the negative feedback, it makes the operation of this system more stable. Estimates suggest that it is possible to compensate approximately one half of heat released from the generator through evaporation of its water of reaction at the electrical efficiency of the electrochemical generator equal to 60%. In this case, even minor increase in the efficiency of the generator would result in a considerable increase in the efficiency of the evaporative system intended for its cooling.

  10. Elimination Of Catalytic Hydrogen Generation In Defense Waste Processing Facility Slurries

    International Nuclear Information System (INIS)

    Based on lab-scale simulations of Defense Waste Processing Facility (DWPF) slurry chemistry, the addition of sodium nitrite and sodium hydroxide to waste slurries at concentrations sufficient to take the aqueous phase into the alkaline region (pH > 7) with approximately 500 mg nitrite ion/kg slurry (assuming < 25 wt% total solids, or equivalently 2,000 mg nitrite/kg total solids) is sufficient to effectively deactivate the noble metal catalysts at temperatures between room temperature and boiling. This is a potential strategy for eliminating catalytic hydrogen generation from the list of concerns for sludge carried over into the DWPF Slurry Mix Evaporator Condensate Tank (SMECT) or Recycle Collection Tank (RCT). These conclusions are drawn in large part from the various phases of the DWPF catalytic hydrogen generation program conducted between 2005 and 2009. The findings could apply to various situations, including a solids carry-over from either the Sludge Receipt and Adjustment Tank (SRAT) or Slurry Mix Evaporator (SME) into the SMECT with subsequent transfer to the RCT, as well as a spill of formic acid into the sump system and transfer into an RCT that already contains sludge solids. There are other potential mitigating factors for the SMECT and RCT, since these vessels are typically operated at temperatures close to the minimum temperatures that catalytic hydrogen has been observed to occur in either the SRAT or SME (pure slurry case), and these vessels are also likely to be considerably more dilute in both noble metals and formate ion (the two essential components to catalytic hydrogen generation) than the two primary process vessels. Rhodium certainly, and ruthenium likely, are present as metal-ligand complexes that are favored under certain concentrations of the surrounding species. Therefore, in the SMECT or RCT, where a small volume of SRAT or SME material would be significantly diluted, conditions would be less optimal for forming or sustaining the

  11. Elimination Of Catalytic Hydrogen Generation In Defense Waste Processing Facility Slurries

    Energy Technology Data Exchange (ETDEWEB)

    Koopman, D. C.

    2013-01-22

    Based on lab-scale simulations of Defense Waste Processing Facility (DWPF) slurry chemistry, the addition of sodium nitrite and sodium hydroxide to waste slurries at concentrations sufficient to take the aqueous phase into the alkaline region (pH > 7) with approximately 500 mg nitrite ion/kg slurry (assuming <25 wt% total solids, or equivalently 2,000 mg nitrite/kg total solids) is sufficient to effectively deactivate the noble metal catalysts at temperatures between room temperature and boiling. This is a potential strategy for eliminating catalytic hydrogen generation from the list of concerns for sludge carried over into the DWPF Slurry Mix Evaporator Condensate Tank (SMECT) or Recycle Collection Tank (RCT). These conclusions are drawn in large part from the various phases of the DWPF catalytic hydrogen generation program conducted between 2005 and 2009. The findings could apply to various situations, including a solids carry-over from either the Sludge Receipt and Adjustment Tank (SRAT) or Slurry Mix Evaporator (SME) into the SMECT with subsequent transfer to the RCT, as well as a spill of formic acid into the sump system and transfer into an RCT that already contains sludge solids. There are other potential mitigating factors for the SMECT and RCT, since these vessels are typically operated at temperatures close to the minimum temperatures that catalytic hydrogen has been observed to occur in either the SRAT or SME (pure slurry case), and these vessels are also likely to be considerably more dilute in both noble metals and formate ion (the two essential components to catalytic hydrogen generation) than the two primary process vessels. Rhodium certainly, and ruthenium likely, are present as metal-ligand complexes that are favored under certain concentrations of the surrounding species. Therefore, in the SMECT or RCT, where a small volume of SRAT or SME material would be significantly diluted, conditions would be less optimal for forming or sustaining the

  12. Adenosine generation catalyzed by CD39 and CD73 expressed on regulatory T cells mediates immune suppression

    OpenAIRE

    Deaglio, Silvia; Dwyer, Karen M.; GAO, WENDA; Friedman, David; Usheva, Anny; Erat, Anna; Chen, Jiang-Fan; Enjyoji, Keiichii; Linden, Joel; Oukka, Mohamed; Kuchroo, Vijay K.; Strom, Terry B.; Robson, Simon C.

    2007-01-01

    The study of T regulatory cells (T reg cells) has been limited by the lack of specific surface markers and an inability to define mechanisms of suppression. We show that the expression of CD39/ENTPD1 in concert with CD73/ecto-5′-nucleotidase distinguishes CD4+/CD25+/Foxp3+ T reg cells from other T cells. These ectoenzymes generate pericellular adenosine from extracellular nucleotides. The coordinated expression of CD39/CD73 on T reg cells and the adenosine A2A receptor on activated T effector...

  13. Comparison of hydrogen production and electrical power generation for energy capture in closed-loop ammonium bicarbonate reverse electrodialysis systems

    KAUST Repository

    Hatzell, Marta C.

    2014-01-01

    Currently, there is an enormous amount of energy available from salinity gradients, which could be used for clean hydrogen production. Through the use of a favorable oxygen reduction reaction (ORR) cathode, the projected electrical energy generated by a single pass ammonium bicarbonate reverse electrodialysis (RED) system approached 78 W h m-3. However, if RED is operated with the less favorable (higher overpotential) hydrogen evolution electrode and hydrogen gas is harvested, the energy recovered increases by as much ∼1.5× to 118 W h m-3. Indirect hydrogen production through coupling an RED stack with an external electrolysis system was only projected to achieve 35 W h m-3 or ∼1/3 of that produced through direct hydrogen generation.

  14. Nonlinear generation of extreme-ultraviolet radiation in atomic hydrogen using electromagnetically induced transparency

    International Nuclear Information System (INIS)

    Sum-frequency generation enhanced by electromagnetically induced transparency (EIT) has been extended to the production of extreme ultraviolet (XUV) radiation in the range 97.3 endash 92.6 nm from np-1s transitions (n=4 endash 8) in atomic hydrogen. Pulsed radiation was generated by strong coupling of the np and 2s levels with laser radiation at Balmer wavelengths, and simultaneously (weaker) coupling of the 2s and 1s levels by two-photon resonance with 243-nm laser radiation. Investigations were carried out over a range of laser intensities and products of interaction length and atomic density (NL). As the product NL increased, the XUV intensities were greatly enhanced by EIT, and at high NL values, the spectral distributions of some of the generated signals were found to be distorted by the presence of molecular hydrogen. Calculated profiles, modified to incorporate the effects of nearby molecular resonances, were shown to be in good agreement with the observed spectra. copyright 1997 The American Physical Society

  15. Development and performance of bench-scale reactor for the photocatalytic generation of hydrogen

    International Nuclear Information System (INIS)

    In this study, a new novel bench-scale (5 L) tubular photocatalytic reactor was developed and its feasibility studies were conducted for optimizing the operating variables, namely concentration of sulfide ion, concentration of sulfite ion, pH, catalyst concentration, lamp power, volume of wastewater and recycle flow rates at batch recycle mode for the generation of hydrogen from aqueous sodium sulfide using CdS–ZnS/TiO2 core–shell NPs (nanoparticles). The maximum H2 generation was found at 0.05 M concentration of sulfide ion, 0.2 M concentration of sulfite ion, pH 11.3, 0.5 g/L catalyst concentration and recycle flow rate of 18 L/h. Reusability studies were conducted for analyzing stability of photocatalyst. The results showed that the generation of hydrogen depends on light intensity, photoreactor used, nature of photocatalysts and the operating conditions. - Highlights: • Clean fuel production using solar energy. • Bench-scale tubular photocatalytic reactor was developed. • Operating variables have significant effect

  16. Hydrogen generation arising from the {sup 59}Ni(n,p) reaction and its impact on fission-fusion correlations

    Energy Technology Data Exchange (ETDEWEB)

    Greenwood, L.R.; Garner, A.F.

    1996-04-01

    Whilte the influence of transmutant helium on radiation-induced microstructural evolution has often been studied, there is a tendency to overlook the influence of concurrently-generated hydrogen. There have been some recent speculation and studies, however, that suggest that the influence of hydrogen may be enhanced in the presence of large amounts of helium, especially at lower irradiation temperatures typical of projected ITER operation. The impact of the (n,p) reaction on both hydrogen generation rates and displacement rates are evaluated in this paper for a variety of neutron spectra employed in fission-fusion correlation.

  17. Hydrogen Peroxide-Resistant CotA and YjqC of Bacillus altitudinis Spores Are a Promising Biocatalyst for Catalyzing Reduction of Sinapic Acid and Sinapine in Rapeseed Meal

    Science.gov (United States)

    Zhang, Yanzhou; Li, Xunhang; Hao, Zhikui; Xi, Ruchun; Cai, Yujie; Liao, Xiangru

    2016-01-01

    For the more efficient detoxification of phenolic compounds, a promising avenue would be to develop a multi-enzyme biocatalyst comprising peroxidase, laccase and other oxidases. However, the development of this multi-enzyme biocatalyst is limited by the vulnerability of fungal laccases and peroxidases to hydrogen peroxide (H2O2)-induced inactivation. Therefore, H2O2-resistant peroxidase and laccase should be exploited. In this study, H2O2-stable CotA and YjqC were isolated from the outer coat of Bacillus altitudinis SYBC hb4 spores. In addition to the thermal and alkali stability of catalytic activity, CotA also exhibited a much higher H2O2 tolerance than fungal laccases from Trametes versicolor and Trametes trogii. YjqC is a sporulation-related manganese (Mn) catalase with striking peroxidase activity for sinapic acid (SA) and sinapine (SNP). In contrast to the typical heme-containing peroxidases, the peroxidase activity of YjqC was also highly resistant to inhibition by H2O2 and heat. CotA could also catalyze the oxidation of SA and SNP. CotA had a much higher affinity for SA than B. subtilis CotA. CotA and YjqC rendered from B. altitudinis spores had promising laccase and peroxidase activities for SA and SNP. Specifically, the B. altitudinis spores could be regarded as a multi-enzyme biocatalyst composed of CotA and YjqC. The B. altitudinis spores were efficient for catalyzing the degradation of SA and SNP in rapeseed meal. Moreover, efficiency of the spore-catalyzed degradation of SA and SNP was greatly improved by the presence of 15 mM H2O2. This effect was largely attributed to synergistic biocatalysis of the H2O2-resistant CotA and YjqC toward SA and SNP. PMID:27362423

  18. Hydrogen

    OpenAIRE

    John O’M. Bockris

    2011-01-01

    The idea of a “Hydrogen Economy” is that carbon containing fuels should be replaced by hydrogen, thus eliminating air pollution and growth of CO2 in the atmosphere. However, storage of a gas, its transport and reconversion to electricity doubles the cost of H2 from the electrolyzer. Methanol made with CO2 from the atmosphere is a zero carbon fuel created from inexhaustible components from the atmosphere. Extensive work on the splitting of water by bacteria shows that if wastes are used as the...

  19. Room temperature hydrogen generation from hydrolysis of ammonia-borane over an efficient NiAgPd/C catalyst

    KAUST Repository

    Hu, Lei

    2014-12-01

    NiAgPd nanoparticles are successfully synthesized by in-situ reduction of Ni, Ag and Pd salts on the surface of carbon. Their catalytic activity was examined in ammonia borane (NH3BH3) hydrolysis to generate hydrogen gas. This nanomaterial exhibits a higher catalytic activity than those of monometallic and bimetallic counterparts and a stoichiometric amount of hydrogen was produced at a high generation rate. Hydrogen production rates were investigated in different concentrations of NH3BH3 solutions, including in the borates saturated solution, showing little influence of the concentrations on the reaction rates. The hydrogen production rate can reach 3.6-3.8 mol H2 molcat -1 min-1 at room temperature (21 °C). The activation energy and TOF value are 38.36 kJ/mol and 93.8 mol H2 molcat -1 min-1, respectively, comparable to those of Pt based catalysts. This nanomaterial catalyst also exhibits excellent chemical stability, and no significant morphology change was observed from TEM after the reaction. Using this catalyst for continuously hydrogen generation, the hydrogen production rate can be kept after generating 6.2 L hydrogen with over 10,000 turnovers and a TOF value of 90.3 mol H2 molcat -1 min-1.

  20. Batch sodium borohydride hydrolysis systems: Effect of sudden valve opening on hydrogen generation rate

    OpenAIRE

    M. J. F. Ferreira; Coelho, F; Rangel, C. M.; Pinto, A. M. F. R.

    2012-01-01

    A study was undertaken in order to investigate the potential of hydrogen (H 2) generation by hydrolysis of sodium borohydride solution (10 wt% NaBH 4 and 7 wt% NaOH), in batch reactors, operating at moderate pressures (up to #8764;1.2 MPa), in the presence of a powdered nickel-ruthenium based catalyst, reused between 311 and 316 times, to feed on-demand a proton exchange membrane fuel cell. A different approach to the testing of the performance of the batch NaBH 4 hydrolysis system is explore...

  1. Water electrolysis with a conducting carbon cloth: subthreshold hydrogen generation and superthreshold carbon quantum dot formation.

    Science.gov (United States)

    Biswal, Mandakini; Deshpande, Aparna; Kelkar, Sarika; Ogale, Satishchandra

    2014-03-01

    A conducting carbon cloth, which has an interesting turbostratic microstructure and functional groups that are distinctly different from other ordered forms of carbon, such as graphite, graphene, and carbon nanotubes, was synthesized by a simple one-step pyrolysis of cellulose fabric. This turbostratic disorder and surface chemical functionalities had interesting consequences for water splitting and hydrogen generation when such a cloth was used as an electrode in the alkaline electrolysis process. Importantly, this work also gives a new twist to carbon-assisted electrolysis. During electrolysis, the active sites in the carbon cloth allow slow oxidation of its surface to transform the surface groups from COH to COOH and so forth at a voltage as low as 0.2 V in a two-electrode system, along with platinum as the cathode, instead of 1.23 V (plus overpotential), which is required for platinum, steel, or even graphite anodes. The quantity of subthreshold hydrogen evolved was 24 mL cm(-2)  h(-1) at 1 V. Interestingly, at a superthreshold potential (>1.23 V+overpotential), another remarkable phenomenon was found. At such voltages, along with the high rate and quantity of hydrogen evolution, rapid exfoliation of the tiny nanoscale (5-7 nm) units of carbon quantum dots (CQDs) are found in copious amounts due to an enhanced oxidation rate. These CQDs show bright-blue fluorescence under UV light. PMID:24492961

  2. Effective regimes of runaway electron beam generation in helium, hydrogen, and nitrogen

    Science.gov (United States)

    Tarasenko, V. F.; Baksht, E. Kh.; Burachenko, A. G.; Lomaev, M. I.; Sorokin, D. A.; Shut'ko, Yu. V.

    2010-04-01

    Runaway electron beam parameters and current-voltage characteristics of discharge in helium, hydrogen, and nitrogen at pressures in the range of several Torr to several hundred Torr have been studied. It is found that the maximum amplitudes of supershort avalanche electron beams (SAEBs) with a pulse full width at half maximum (FWHM) of ˜100 ps are achieved in helium, hydrogen, and nitrogen at a pressure of ˜60, ˜30, and ˜10 Torr, respectively. It is shown that, as the gas pressure is increased in the indicated range, the breakdown voltage of the gas-filled gap decreases, which leads to a decrease in the SAEB current amplitude. At pressures of helium within 20-60 Torr, hydrogen within 10-30 Torr, and nitrogen within 3-10 Torr, the regime of the runaway electron beam generation changes and, by varying the pressure in the gas-filled diode in the indicated intervals, it is possible to smoothly control the current pulse duration (FWHM) from ˜100 to ˜500 ps, while the beam current amplitude increases by a factor of 1.5-3.

  3. Efficient photocatalytic hydrogen generation by silica supported and platinum promoted titanium dioxide

    International Nuclear Information System (INIS)

    mol/h/g of TiO2 and that for P-25 is 161 μmol/h/g of TiO2 under visible light irradiation. The value is 30 times higher than benchmark material Degussa P-25. This photocatalyst is also found stable up to 24 h without replenishing with sacrificial donor ethanol. However silica gel/TiO2/Ru does not show any exciting result for hydrogen generation. The effect of various operating parameters like photocatalyst loading, Illumination time and intensity of light on supported photocatalyst also has been studied

  4. Cytochrome c catalyzes the in vitro synthesis of arachidonoyl glycine

    International Nuclear Information System (INIS)

    Long chain fatty acyl glycines are an emerging class of biologically active molecules that occur naturally and produce a wide array of physiological effects. Their biosynthetic pathway, however, remains unknown. Here we report that cytochrome c catalyzes the synthesis of N-arachidonoyl glycine (NAGly) from arachidonoyl coenzyme A and glycine in the presence of hydrogen peroxide. The identity of the NAGly product was verified by isotope labeling and mass analysis. Other heme-containing proteins, hemoglobin and myoglobin, were considerably less effective in generating arachidonoyl glycine as compared to cytochrome c. The reaction catalyzed by cytochrome c in vitro points to its potential role in the formation of NAGly and other long chain fatty acyl glycines in vivo

  5. Iodine-catalyzed coal liquefaction

    Energy Technology Data Exchange (ETDEWEB)

    Joseph, J.T.; Duffield, J.E.; Davidson, M.G. (Amoco Oil Company, Naperville, IL (USA). Research and Development Dept.)

    Coals of two different ranks were liquefied in high yields using catalytic quantities of elemental iodine or iodine compounds. Iodine monochloride was found to be especially effective for enhancing both coal conversion and product quality. It appears that enhancement in coal conversion is due to the unique ability of iodine to catalyze radical-induced bond scission and hydrogen addition to the coal macromolecule or coal-derived free radicals. The starting iodine can be fully accounted for in the reaction products as both organic-bound and water-soluble forms. Unconverted coal and the heavy product fractions contain the majority of the organic-bound iodine. The results of iodine-catalyzed coal reactions emphasize the need for efficient hydrogen atom transfer along with bond scission to achieve high conversion and product quality. 22 refs., 12 tabs.

  6. Studies of Heterogeneously Catalyzed Liquid-Phase Alcohol Oxidation on Platinum bySum-frequency Generation Vibrational Spectroscopy and Reaction Rate Measurements

    Energy Technology Data Exchange (ETDEWEB)

    Thompson, Christopher [Univ. of California, Berkeley, CA (United States)

    2014-05-15

    Compared to many branches of chemistry, the molecular level study of catalytically active surfaces is young. Only with the invention of ultrahigh vacuum technology in the past half century has it been possible to carry out experiments that yield useful molecular information about the reactive occurrences at a surface. The reason is two-fold: low pressure is necessary to keep a surface clean for an amount of time long enough to perform an experiment, and most atomic scale techniques that are surface speci c (x-ray photoelectron spectroscopy, electron energy loss spectroscopy, Auger electron spectroscopy, etc.) cannot be used at ambient pressures, because electrons, which act as chemical probes in these techniques, are easily scattered by molecules. Sum-frequency generation (SFG) vibrational spectroscopy is one technique that can provide molecular level information from the surface without the necessity for high vacuum. Since the advent of SFG as a surface spectroscopic tool it has proved its worth in the studies of surface catalyzed reactions in the gas phase, with numerous reactions in the gas phase having been investigated on a multitude of surfaces. However, in situ SFG characterization of catalysis at the solid-liquid interface has yet to be thoroughly pursued despite the broad interest in the use of heterogeneous catalysts in the liquid phase as replacements for homogeneous counterparts. This work describes an attempt to move in that direction, applying SFG to study the solid-liquid interface under conditions of catalytic alcohol oxidation on platinum.

  7. Ruthenium-BINAP Catalyzed Alcohol C-H tert-Prenylation via 1,3-Enyne Transfer Hydrogenation: Beyond Stoichiometric Carbanions in Enantioselective Carbonyl Propargylation.

    Science.gov (United States)

    Nguyen, Khoa D; Herkommer, Daniel; Krische, Michael J

    2016-04-27

    The chiral ruthenium complex formed in situ from (TFA)2Ru(CO)(PPh3)2 and (R)-BINAP is found to catalyze the enantioselective C-C coupling of diverse primary alcohols with the 1,3-enyne, TMSC≡CC(Me)═CH2, to form secondary homopropargyl alcohols bearing gem-dimethyl groups. All reagents for this byproduct-free coupling are inexpensive and commercially available, making this protocol a practical alternative to stoichiometric carbanions in enantioselective carbonyl reverse prenylation. PMID:27079149

  8. Muon catalyzed fusion experiments in thin films and slow negative muon production

    International Nuclear Information System (INIS)

    Muon-catalyzed fusion has been studied in many ways for energy production, however, it has several other applications, for example, an intense fusion neutron source can be produced by the muon-catalyzed fusion in a high density deuterium-tritium mixture. Moreover, intense slow negative muons can also be generated from the successive liberation of -10 keV muons in the muon-catalyzed reaction. Before reaching this hypothetical goal of intense slow negative muon production, a new experimental technique must be developed first to perform muon-catalyzed fusion studies in thin solid hydrogen isotope mixtures at very low temperature to determine the feasibility of this method. Because of the difficulties in handling tritium, the experiment in pure deuterium solid films was adopted. The main objective is to optimize the deuterium layer thickness to maximize slow negative muon emission from the surface. The principle, the experimental method, the experimental setup and the results of muonic hydrogen Kα X-ray, fusion protons and slow negative muon detection, and the Monte Carlo simulation of muon-catalyzed fusion kinetics are reported. Two different contributions to the total fusion yield were observed. (K.I.)

  9. Hydrogen peroxide generation by the Weissberger biogenic oxidative system during hyaluronan degradation.

    Science.gov (United States)

    Valachová, Katarina; Topoľská, Dominika; Mendichi, Raniero; Collins, Maurice N; Sasinková, Vlasta; Šoltés, Ladislav

    2016-09-01

    By applying the enzyme catalase, our study on hyaluronan degradation confirms the generation of hydrogen peroxide using the Weissberger biogenic oxidative system (WBOS), which is composed of ascorbate and cupric ions. Dynamic viscosities of hyaluronan (HA) solutions influenced by WBOS in the absence and presence of catalase were analysed by rotational viscometry. Molar masses of HAs were determined by size-exclusion chromatography with multi-angle laser-light scattering. Our results show that catalase dose-dependently inhibited the degradation of HA macromolecules, which presumably confirms the generation of H2O2 in the reaction system. This has implications in range of biomedical applications such as arthritic joint treatment, tissue engineering, ocular and cosmetic surgery. PMID:27185130

  10. The next generation of CANDU technologies: profiling the potential for hydrogen fuel

    International Nuclear Information System (INIS)

    This report discusses the Next-generation CANDU Power Reactor technologies currently under development at AECL. The innovations introduced into proven CANDU technologies include a compact reactor core design, which reduces the size by a factor of one third for the same power output; improved thermal efficiency through higher-pressure steam turbines; reduced use of heavy water (one quarter of the heavy water required for existing plants), thus reducing the cost and eliminating many material handling concerns; use of slightly enriched uranium to extend fuel life to three times that of existing natural uranium fuel and additions to CANDU's inherent passive safety. With these advanced features, the capital cost of constructing the plant can be reduced by up to 40 per cent compared to existing designs. The clean, affordable CANDU-generated electricity can be used to produce hydrogen for fuel cells for the transportation sector, thereby reducing emissions from the transportation sector

  11. Fabrication of nanocomposites composed of silver cyanamide and titania for improved photocatalytic hydrogen generation.

    Science.gov (United States)

    Meng, Hao; Li, Xiaoxue; Zhang, Xia; Liu, Yufeng; Xu, Yan; Han, Yide; Xu, Junli

    2015-12-14

    Highly efficient composite photocatalysts composed of silver cyanamide (Ag2NCN) and anatase titania (TiO2) were fabricated through a chemical precipitation process of silver nitrate and cyanamide in TiO2 suspensions. The TiO2 nanoparticles around 15 nm were immobilized on the surface of rectangular Ag2NCN particles to form a hetero-structure, and the contents of TiO2 were varied to tune the structure and the photocatalytic performances. In comparison with single TiO2 or Ag2NCN, the TiO2/Ag2NCN nanocomposites exhibited a prominent improved photocatalytic activity in the hydrogen generation, and the hydrogen evolution rate (1494.0 μmol (g h)(-1)) was higher than most of the reported TiO2-composite photocatalysts. Based on the structure investigation, the photocatalytic mechanism of these TiO2/Ag2NCN nanocomposites was proposed. The enhanced photocatalytic activity was attributed to three points: the matched energy level between TiO2 and Ag2NCN promoted the electron-hole transfer and thus inhibited the recombination of photogenerated electrons and holes; the great electron storage capacity of metallic silver produced in the photocatalytic process also facilitated the charge separation; in addition, the expanded absorption spectrum because of the composite structure enhanced the UV and visible light response ability. These TiO2/Ag2NCN nanocomposites also presented good photocatalytic stability in the typical cycle tests. This work provided new insights into fabricating highly efficient composite photocatalysts containing silver and TiO2 for hydrogen generation. PMID:26515664

  12. Leak detection in steam generators with hydrogen monitors using diffusion membranes

    International Nuclear Information System (INIS)

    Large water leaks in steam-generators give rise to violent chemical reactions which can only be controlled by a pressure relief system. Smaller leaks do not pose direct safety hazards but wastage of pipes surrounding the leak should be prevented. Leak detection is best carried out by monitors recording the hydrogen in sodium content. For large leaks the specification of these monitors causes no problems, contrary to those for the timely detection of small leaks. Essential parameters are sensitivity and speed of response, specificity is less important. But apart from the instrument specification, a number of factors, related to the construction and operation of the steam-generator, determine the performance of the leak detection system. A discussion of these factors is given, with a view to the design of the SNR-300. Although tile results of many theoretical studies and experimental work are available, there seems to be room for further investigations on the growths of minor leaks. Also lacking a sufficient experience concerning the level and fluctuations of the hydrogen background in the sodium. A description is given of the hydrogen monitor developed at TNO, which is based on a combination of a nickel membrane and an ion getter pump. The parameters of this instrument have been evaluated in a test rig. Operational experience with the monitor is available from the 50 MW Test Facility at Hengelo. Especially for further studies the need for a calibrated instrument has become apparent. Test are going on with a modified design of a monitor meeting this requirement. (author)

  13. Synthesis and Characterization of K-Ta Mixed Oxides for Hydrogen Generation in Photocatalysis

    Directory of Open Access Journals (Sweden)

    Beata Zielińska

    2012-01-01

    Full Text Available K-Ta mixed oxides photocatalysts have been prepared by impregnation followed by calcination. The influence of the reaction temperature (450°C–900°C on the phase formation, crystal morphology, and photocatalytic activity in hydrogen generation of the produced materials was investigated. The detailed analysis has revealed that all products exhibit high crystallinity and irregular structure. Moreover, two different crystal structures of potassium tantalates such as KTaO3 and K2Ta4O11 were obtained. It was also found that the sample composed of KTaO3 and traces of unreacted Ta2O5 (annealed at 600°C exhibits the highest activity in the reaction of photocatalytic hydrogen generation. The crystallographic phases, optical and vibronic properties were examined by X-ray diffraction (XRD and diffuse reflectance (DR UV-vis and resonance Raman spectroscopic methods, respectively. Morphology and chemical composition of the produced samples were studied using a high-resolution transmission electron microscope (HR-TEM and an energy dispersive X-ray spectrometer (EDX as its mode.

  14. Hydrogen

    Directory of Open Access Journals (Sweden)

    John O’M. Bockris

    2011-11-01

    Full Text Available The idea of a “Hydrogen Economy” is that carbon containing fuels should be replaced by hydrogen, thus eliminating air pollution and growth of CO2 in the atmosphere. However, storage of a gas, its transport and reconversion to electricity doubles the cost of H2 from the electrolyzer. Methanol made with CO2 from the atmosphere is a zero carbon fuel created from inexhaustible components from the atmosphere. Extensive work on the splitting of water by bacteria shows that if wastes are used as the origin of feed for certain bacteria, the cost for hydrogen becomes lower than any yet known. The first creation of hydrogen and electricity from light was carried out in 1976 by Ohashi et al. at Flinders University in Australia. Improvements in knowledge of the structure of the semiconductor-solution system used in a solar breakdown of water has led to the discovery of surface states which take part in giving rise to hydrogen (Khan. Photoelectrocatalysis made a ten times increase in the efficiency of the photo production of hydrogen from water. The use of two electrode cells; p and n semiconductors respectively, was first introduced by Uosaki in 1978. Most photoanodes decompose during the photoelectrolysis. To avoid this, it has been necessary to create a transparent shield between the semiconductor and its electronic properties and the solution. In this way, 8.5% at 25 °C and 9.5% at 50 °C has been reached in the photo dissociation of water (GaP and InAs by Kainthla and Barbara Zeleney in 1989. A large consortium has been funded by the US government at the California Institute of Technology under the direction of Nathan Lewis. The decomposition of water by light is the main aim of this group. Whether light will be the origin of the post fossil fuel supply of energy may be questionable, but the maximum program in this direction is likely to come from Cal. Tech.

  15. Iridium‐Catalyzed Dehydrogenative Decarbonylation of Primary Alcohols with the Liberation of Syngas

    DEFF Research Database (Denmark)

    Olsen, Esben Paul Krogh; Madsen, Robert

    2012-01-01

    A new iridium‐catalyzed reaction in which molecular hydrogen and carbon monoxide are cleaved from primary alcohols in the absence of any stoichiometric additives has been developed. The dehydrogenative decarbonylation was achieved with a catalyst generated in situ from [Ir(coe)2Cl]2 (coe=cyclooct......A new iridium‐catalyzed reaction in which molecular hydrogen and carbon monoxide are cleaved from primary alcohols in the absence of any stoichiometric additives has been developed. The dehydrogenative decarbonylation was achieved with a catalyst generated in situ from [Ir(coe)2Cl]2 (coe......, dehydrogenation of the primary alcohol to the corresponding aldehyde takes place, which is then followed by decarbonylation to the product with one less carbon atom....

  16. Hydrogen sensor

    Science.gov (United States)

    Duan, Yixiang; Jia, Quanxi; Cao, Wenqing

    2010-11-23

    A hydrogen sensor for detecting/quantitating hydrogen and hydrogen isotopes includes a sampling line and a microplasma generator that excites hydrogen from a gas sample and produces light emission from excited hydrogen. A power supply provides power to the microplasma generator, and a spectrometer generates an emission spectrum from the light emission. A programmable computer is adapted for determining whether or not the gas sample includes hydrogen, and for quantitating the amount of hydrogen and/or hydrogen isotopes are present in the gas sample.

  17. Effect of ball-milling duration and dehydrogenation on the morphology, microstructure and catalyst dispersion in Ni-catalyzed MgH2 hydrogen storage materials

    International Nuclear Information System (INIS)

    The effects of high-energy ball-milling on catalyst morphology and dispersion as a function of milling duration and on hydrogen desorption were investigated. Samples of MgH2 doped with 0.05 Ni catalyst were examined after 1, 5 and 10 h of milling. Longer milling durations produced finer catalyst particle sizes and more uniform dispersions, but yielded higher hydrogen desorption temperatures. This behavior is attributed to the formation of Mg2NiH4 with increased milling times. Electron tomography was used to show that the Ni particles reside both inside and outside the MgH2 particles. On dehydrogenation there was a redistribution of catalyst and continued formation of Mg2Ni. The formation of this phase is proposed to explain the reported degradation of hydrogen capacity and the change in kinetics of this system with cycling

  18. Probing the Mechanism of 1,4-Conjugate Elimination Reactions Catalyzed by Terpene Synthases

    OpenAIRE

    Faraldos, Juan A.; Gonzalez, Veronica; Li, Amang; Yu, Fanglei; Köksal, Mustafa; Christianson, David W.; Allemann, Rudolf K.

    2012-01-01

    The reaction mechanisms of (E)-β-farnesene synthase (EBFS) and isoprene synthase (ISPS), enzymes that catalyze a formal regioespecific 1,4-conjugate elimination of hydrogen-diphosphate from (E, E)-farnesyl and dimethylallyl diphosphate (FDP and DMADP) to generate the semiochemicals (E)-β-farnesene and isoprene, respectively, were probed with substrate analogs and kinetic measurements. The results support stepwise reaction mechanisms through analogous enzyme-bound allylic cationic intermediate...

  19. Dibenzothiophene hydrodesulfurization over Ru promoted alumina based catalysts using in situ generated hydrogen

    International Nuclear Information System (INIS)

    Catalytic hydrodesulfurization (HDS) of dibenzothiophene (DBT) was carried out in a temperature range of 320-400 oC using in situ generated hydrogen coupled with the effect of selected organic additives for the first time. Four kinds of alumina based catalysts i.e. Co-Mo/Al2O3, Ni-Mo/Al2O3, Ru-Co-Mo/Al2O3 and Ru-Ni-Mo/Al2O3 were used for the desulfurization process, which were prepared following incipient impregnation method with fixed metal loadings (wt.%) of Co, Ni, Mo and Ru. The surface area, average pore diameter and pore volume distribution of the fresh and used catalysts were measured by N2 adsorption using BET method. Catalytic activity was investigated in a batch autoclave reactor in the complete absence of external hydrogen gas. Addition and mutual reaction of specific quantities of water and ethanol provided the necessary in situ hydrogen for the desulfurization reaction. Organic additives like diethylene glycol (DEG), phenol, naphthalene, anthracene, o-xylene, tetralin, decalin and pyridine did impinge the HDS activity of the catalysts in different ways. Liquid samples from reaction products were quantitatively analyzed by HPLC technique while qualitative analyses were made using GC-MS. Both of these techniques showed that Ni-based catalysts were more active than Co-based ones at all conditions. Moreover, incorporation of Ru to both Co and Ni-based catalysts greatly promoted desulfurization activity of these catalysts. DBT conversion of up to 84% was achieved with Ru-Ni-Mo/Al2O3 catalyst at 380 oC temperature for 11 h. Catalyst systems followed the HDS activity order as: Ru-Ni-Mo/Al2O3 > Ni-Mo/Al2O3 > Ru-Co-Mo/Al2O3 > Co-Mo/Al2O3 at all conditions. Cost effectiveness, mild operating conditions and reasonably high catalytic activity using in situ generated hydrogen mechanism proved our process to be useful for HDS of DBT.

  20. Hydrogen generation by Rhodobacter spahaeroides O.U. 001: the effect of photo-bioreactor construction material

    International Nuclear Information System (INIS)

    Generation of hydrogen by purple, non-sulfur bacteria of Rhodobacter sphaeroides O.U.001 was tested in photo-bioreactors made of different materials. Reactors made of ordinary sodium-type glass, borosilicate glass (Pyrex) or polycarbonate were applied in the present study. The applied medium containing malic acid and sodium glutamate inoculated with 0.11 or 0.31 g dry wt. of Rhodobacater sphaeroides was illuminated with 5 or 17 klx. Simultaneous measurements of evolved hydrogen, biomass growth, and COD were performed. The concentration of carotenoids and bacterio-chlorophyll was tested. In all tests the highest yield of hydrogen was obtained applying sodium glass photo-bioreactors illuminated with of 5 klx. Application of borosilicate glass or polycarbonate reactors reduced the amount of evolved hydrogen by 75 %. The best yield of hydrogen (2.1 dm3 of H2 per dm3 of medium) was obtained after illumination with 5 klx. (authors)

  1. Initial Screening of Thermochemical Water-Splitting Cycles for High Efficiency Generation of Hydrogen Fuels Using Nuclear Power

    International Nuclear Information System (INIS)

    OAK B188 Initial Screening of Thermochemical Water-Splitting Cycles for High Efficiency Generation of Hydrogen Fuels Using Nuclear Power There is currently no large scale, cost-effective, environmentally attractive hydrogen production process, nor is such a process available for commercialization. Hydrogen is a promising energy carrier, which potentially could replace the fossil fuels used in the transportation sector of our economy. Fossil fuels are polluting and carbon dioxide emissions from their combustion are thought to be responsible for global warming. The purpose of this work is to determine the potential for efficient, cost-effective, large-scale production of hydrogen utilizing high temperature heat from an advanced nuclear power station. Almost 800 literature references were located which pertain to thermochemical production of hydrogen from water and over 100 thermochemical watersplitting cycles were examined. Using defined criteria and quantifiable metrics, 25 cycles have been selected for more detailed study

  2. Hydrogen peroxide generation and photocatalytic degradation of estrone by microstructural controlled ZnO nanorod arrays

    International Nuclear Information System (INIS)

    Highlights: ► H2O2 generated by ZnO nanorod arrays during UV irradiation was detected. ► ZnO nanorod arrays were synthesized via a facile hydrothermal technique. ► The microstructure can be controlled by varying reactants’ concentration. ► Photocatalytic degradation of estrone by ZnO nanorod arrays was studied. ► Microstructures’ effect on photocatalysis and H2O2 generation was discussed. - Abstract: The strong oxidant, hydrogen peroxide (H2O2), generated by ZnO nanorod arrays under UV light irradiation was monitored by fluorescence analysis. The ZnO nanorod arrays were synthesized via a low temperature hydrothermal method and their dimensions, i.e., diameter and height, can be controlled by adjusting the concentration of zinc nitrate (Zn(NO3)2·6H2O) and hexamethylenetetramine (HMT). The morphology, nanostructure, surface roughness and optical property were characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD), atomic force microscopy (AFM) and transmittance spectra, respectively. The ZnO nanorod arrays were applied in the degradation of estrone, which is an emerging steroid estrogen contaminant. The results revealed that the ZnO nanorod array produced from 25 mM Zn2+ and HMT had the highest aspect ratio, the largest surface roughness and the lowest band gap energy, which was beneficial to the efficiency of UV light utilization, photocatalytic degradation of estrone and H2O2 generation.

  3. Inhibition of hydrogen sulfide generation from disposed gypsum drywall using chemical inhibitors.

    Science.gov (United States)

    Xu, Qiyong; Townsend, Timothy; Bitton, Gabriel

    2011-07-15

    Disposal of gypsum drywall in landfills has been demonstrated to elevate hydrogen sulfide (H(2)S) concentrations in landfill gas, a problem with respect to odor, worker safety, and deleterious effect on gas-to-energy systems. Since H(2)S production in landfills results from biological activity, the concept of inhibiting H(2)S production through the application of chemical agents to drywall during disposal was studied. Three possible inhibition agents - sodium molybdate (Na(2)MoO(4)), ferric chloride (FeCl(3)), and hydrated lime (Ca(OH)(2)) - were evaluated using flask and column experiments. All three agents inhibited H(2)S generation, with Na(2)MoO(4) reducing H(2)S generation by interrupting the biological sulfate reduction process and Ca(OH)(2) providing an unfavorable pH for biological growth. Although FeCl(3) was intended to provide an electron acceptor for a competing group of bacteria, the mechanism found responsible for inhibiting H(2)S production in the column experiment was a reduction in pH. Application of both Na(2)MoO(4) and FeCl(3) inhibited H(2)S generation over a long period (over 180 days), but the impact of Ca(OH)(2) decreased with time as the alkalinity it contributed was neutralized by the generated H(2)S. Practical application and potential environmental implications need additional exploration. PMID:21592650

  4. Inhibition of hydrogen sulfide generation from disposed gypsum drywall using chemical inhibitors

    International Nuclear Information System (INIS)

    Disposal of gypsum drywall in landfills has been demonstrated to elevate hydrogen sulfide (H2S) concentrations in landfill gas, a problem with respect to odor, worker safety, and deleterious effect on gas-to-energy systems. Since H2S production in landfills results from biological activity, the concept of inhibiting H2S production through the application of chemical agents to drywall during disposal was studied. Three possible inhibition agents - sodium molybdate (Na2MoO4), ferric chloride (FeCl3), and hydrated lime (Ca(OH)2) - were evaluated using flask and column experiments. All three agents inhibited H2S generation, with Na2MoO4 reducing H2S generation by interrupting the biological sulfate reduction process and Ca(OH)2 providing an unfavorable pH for biological growth. Although FeCl3 was intended to provide an electron acceptor for a competing group of bacteria, the mechanism found responsible for inhibiting H2S production in the column experiment was a reduction in pH. Application of both Na2MoO4 and FeCl3 inhibited H2S generation over a long period (over 180 days), but the impact of Ca(OH)2 decreased with time as the alkalinity it contributed was neutralized by the generated H2S. Practical application and potential environmental implications need additional exploration.

  5. STANDALONE &LDQUO;GREEN&RDQUO; COMMUNITY-CENTER BUILDINGS: HYDROGEN GENERATION/STORAGE/DELIVERY SYSTEM FOR WHEN PRIMARY ENERGY STORAGE IS AT CAPACITY

    Science.gov (United States)

    Overall, the implementation of a computer-controlled hydrogen generation system and subsequent conversion of small engine equipment for hydrogen use has been surprisingly straightforward from an engineering and technology standpoint. More testing is required to get a better gr...

  6. Vanadium Hydrogen Sulfate Catalyzed Solvent-Free Synthesis of 3,4-Dihydropyrimidin-2(1H)-ones and Bis-(indolyl) methanes

    International Nuclear Information System (INIS)

    We have developed a mild, simple and efficient method for the synthesis of 3,4-dihydropyrimidin-2(1H)-ones/thiones and bis-(indolyl) methanes catalyzed by V(HSO4)3. Based on our studies, this method offers several adavantages including mild reaction conditions, good to high yields of the products, short reaction times, solvent-free reaction conditions and simple experimental procedure. 3,4-Dihydropyrimidin-2(1H)-ones and their derivatives have attracted increasing interest due to their wide range of therapeutical and pharmacological properties, such as antiviral, antitumor, antibacterial, and antiinflammatory properties. Some of them have been successfully used as calcium channel blockers, antihypertensive agents, and α1a-antagonists. Moreover, several marine alkaloids whose molecular structures contain the dihydropyrimidinone core also exhibit interesting biological activities. Therefore, synthesis of these type of compounds is still of great importance

  7. Redirection of metabolism for hydrogen production

    Energy Technology Data Exchange (ETDEWEB)

    Harwood, Caroline S.

    2011-11-28

    This project is to develop and apply techniques in metabolic engineering to improve the biocatalytic potential of the bacterium Rhodopseudomonas palustris for nitrogenase-catalyzed hydrogen gas production. R. palustris, is an ideal platform to develop as a biocatalyst for hydrogen gas production because it is an extremely versatile microbe that produces copious amounts of hydrogen by drawing on abundant natural resources of sunlight and biomass. Anoxygenic photosynthetic bacteria, such as R. palustris, generate hydrogen and ammonia during a process known as biological nitrogen fixation. This reaction is catalyzed by the enzyme nitrogenase and normally consumes nitrogen gas, ATP and electrons. The applied use of nitrogenase for hydrogen production is attractive because hydrogen is an obligatory product of this enzyme and is formed as the only product when nitrogen gas is not supplied. Our challenge is to understand the systems biology of R. palustris sufficiently well to be able to engineer cells to produce hydrogen continuously, as fast as possible and with as high a conversion efficiency as possible of light and electron donating substrates. For many experiments we started with a strain of R. palustris that produces hydrogen constitutively under all growth conditions. We then identified metabolic pathways and enzymes important for removal of electrons from electron-donating organic compounds and for their delivery to nitrogenase in whole R. palustris cells. For this we developed and applied improved techniques in 13C metabolic flux analysis. We identified reactions that are important for generating electrons for nitrogenase and that are yield-limiting for hydrogen production. We then increased hydrogen production by blocking alternative electron-utilizing metabolic pathways by mutagenesis. In addition we found that use of non-growing cells as biocatalysts for hydrogen gas production is an attractive option, because cells divert all resources away from growth and

  8. A MultiObjective Genetic Algorithm Framework for electricity / hydrogen co-production from generation IV nuclear energy systems

    OpenAIRE

    Azzaro-Pantel, Catherine; Domenech, Serge; Dumaz, Patrick; Gomez, Adrien; Haubensack, David; Latgé, Christian; Pibouleau, Luc

    2009-01-01

    One of the great motivations of studying and developing Generation IV (Gen IV) reactors of VHTR (Very High Temperature Reactor) design is their capacity to efficiently produce both electricity and H2 (hydrogen). This study aims at developing an optimization methodology for cogeneration systems of hydrogen and electricity, with respect to energy constraints, economics and conjuncture in terms of demand. It lies within the scope of a collaboration between the Laboratoire de Génie Chimique (LGC ...

  9. Studies on the permeation of hydrogen through steam generator tubes at high temperatures using an electrochemical method

    International Nuclear Information System (INIS)

    The permeation of hydrogen through steam generator tubes at high temperatures (∼ 300 degrees C) has been studied using an electrochemical technique. With this technique, hydrogen is generated on one side of the tube and monitored on the other side. The time for the hydrogen to reach the other side is used to determine the diffusion coefficient of hydrogen in the tube. Boundary conditions at the entry and exit sides have been investigated separately. Preliminary studies were performed on Stainless Steel 316 and Nickel Alloy 800 to better understand the influence of the solution chemistry on the electrochemical evolution of hydrogen. The surface phenomena effect and the trapping effect are discussed to account for differences observed in the permeation response. The hydrogen permeation through oxides at the exit side has been studied. Two nickel alloys (Alloy 800 and Alloy 600), materials widely used for steam generator tubes, have been investigated. The tubes were prefilmed using two different treatments. The oxides were formed in dry air at high temperatures (300 degrees C to 600 degrees C), or in humid gas at 300 degrees C. The diffusion coefficients at 300 degrees C in Stainless Steel 316 and Alloy 800 were determined to be of the order of 10-6 - 10-7 cm2/s for the bare metal. This is in agreement with results obtained by gas phase permeation techniques in the literature. (author)

  10. Calibration and performance of the PFR steam - generating unit gas-space hydrogen detection system at high hydrogen partial pressures

    International Nuclear Information System (INIS)

    The PFR secondary circuit hydrogen detection system was calibrated at levels up to 20% hydrogen in argon, in order to follow quantitatively the hydrogen build-up as a consequence of small gas-space evaporator steam/water to sodium leaks. This is a pre-requisite for determining steam/water to sodium leak rates. Experiments conducted over the temperature range 388 - 530 0C show that the response of the nickel permeation membrane is non-linear, even at hundreds of volume parts per million H2 in Ar. Good correlation between experimental results and permeation theory (based on Ficks laws) was obtained, after correcting where necessary for the non-linear katharometer response. These thermal conductivity detectors tend to read lower than absolute above about 0.5% H2 in Ar. (author)

  11. Efficiency Evaluation of a Photovoltaic System Simultaneously Generating Solar Electricity and Hydrogen for Energy Storage

    Directory of Open Access Journals (Sweden)

    Abermann S.

    2012-10-01

    Full Text Available The direct combination of a photovoltaic system with an energy storage component appears desirable since it produces and stores electrical energy simultaneously, enabling it to compensate power generation fluctuations and supply sufficient energy during low- or non-irradiation periods. A novel concept based on hydrogenated amorphous silicon (a-Si:H triple-junction solar cells, as for example a-Si:H/a-SiGe:H/a-SiGe:H, and a solar water splitting system integrating a polymer electrolyte membrane (PEM electrolyser is presented. The thin film layer-by-layer concept allows large-area module fabrication applicable to buildings, and exhibits strong cost-reduction potential as compared to similar concepts. The evaluation shows that it is possible to achieve a sufficient voltage of greater than 1.5 V for effective water splitting with the a-Si based solar cell. Nevertheless, in the case of grid-connection, the actual energy production cost for hydrogen storage by the proposed system is currently too high.

  12. Generation of hydrogen peroxide from San Joaquin Valley particles in a cell-free solution

    Science.gov (United States)

    Shen, H.; Barakat, A. I.; Anastasio, C.

    2011-01-01

    Epidemiological studies have shown a correlation between exposure to ambient particulate matter (PM) and adverse health effects. One proposed mechanism of PM-mediated health effects is the generation of reactive oxygen species (ROS) - e.g., superoxide (•O2-), hydrogen peroxide (HOOH), and hydroxyl radical (•OH) - followed by oxidative stress. There are very few quantitative, specific measures of individual ROS generated from PM, but this information would help to more quantitatively address the link between ROS and the health effects of PM. To address this gap, we quantified the generation of HOOH by PM collected at an urban (Fresno) and rural (Westside) site in the San Joaquin Valley (SJV) of California during summer and winter from 2006 to 2009. HOOH was quantified by HPLC after extracting the PM in a cell-free, phosphate-buffered saline (PBS) solution with or without 50 μM ascorbate (Asc). Our results show that the urban PM generally generates much more HOOH than the rural PM but that there is no apparent seasonal difference in HOOH generation. In nearly all of the samples the addition of a physiologically relevant concentration of Asc greatly enhances HOOH formation, but a few of the coarse PM samples were able to generate a considerable amount of HOOH in the absence of added Asc, indicating the presence of unknown reductants. Normalized by air volume, the fine PM (PM2.5) generally makes more HOOH than the corresponding coarse PM (PMcf, i.e., 2.5 to 10 μm), primarily because the mass concentration of PM2.5 is much higher than that of PMcf. However, normalized by PM mass, the coarse PM typically generates more HOOH than the fine PM. The amount of HOOH produced by SJV PM is reduced on average by (78 ± 15)% when the transition metal chelator desferoxamine (DSF) is added to the extraction solution, indicating that transition metals play a dominant role in HOOH generation. By measuring calibration curves of HOOH generation from copper, and quantifying copper

  13. Generation of hydrogen peroxide from San Joaquin Valley particles in a cell-free solution

    Directory of Open Access Journals (Sweden)

    H. Shen

    2010-09-01

    Full Text Available Epidemiological studies have shown a correlation between exposure to ambient particulate matter (PM and adverse health effects. One proposed mechanism of PM-mediated health effects is the generation of reactive oxygen species (ROS – e.g., superoxide (•O2, hydrogen peroxide (HOOH, and hydroxyl radical (•OH – followed by oxidative stress. There are very few quantitative, specific measures of individual ROS generated from PM, but this information would help to more quantitatively address the link between ROS and the health effects of PM. To address this gap, we quantified the generation of HOOH by PM collected at an urban (Fresno and rural (Westside site in the San Joaquin Valley (SJV of California during summer and winter from 2006 to 2009. HOOH was quantified by HPLC after extracting the PM in a cell-free, phosphate-buffered saline (PBS solution with or without 50 μM ascorbate (Asc. Our results show that the urban PM generally generates much more HOOH than the rural PM but that there is no apparent seasonal difference in HOOH generation. In nearly all of the samples the addition of a physiologically relevant concentration of Asc greatly enhances HOOH formation, but a few of the coarse PM samples were able to generate a considerable amount of HOOH in the absence of added Asc, indicating the presence of unknown reductants. Normalized by air volume, the fine PM (PM2.5 generally makes more HOOH than the corresponding coarse PM (PMcf, i.e., 2.5 to 10 μm, primarily because the mass concentration of PM2.5 is much higher than that of PMcf. However, normalized by PM mass, the coarse PM typically generates more HOOH than the fine PM. The amount of HOOH produced by SJV PM is reduced on average by (78±15% when the transition metal chelator desferoxamine (DSF is added to the extraction solution, indicating that transition metals play a dominant role in HOOH generation. By

  14. Generation of hydrogen peroxide from San Joaquin Valley particles in a cell-free solution

    Directory of Open Access Journals (Sweden)

    H. Shen

    2011-01-01

    Full Text Available Epidemiological studies have shown a correlation between exposure to ambient particulate matter (PM and adverse health effects. One proposed mechanism of PM-mediated health effects is the generation of reactive oxygen species (ROS – e.g., superoxide (O2, hydrogen peroxide (HOOH, and hydroxyl radical (OH – followed by oxidative stress. There are very few quantitative, specific measures of individual ROS generated from PM, but this information would help to more quantitatively address the link between ROS and the health effects of PM. To address this gap, we quantified the generation of HOOH by PM collected at an urban (Fresno and rural (Westside site in the San Joaquin Valley (SJV of California during summer and winter from 2006 to 2009. HOOH was quantified by HPLC after extracting the PM in a cell-free, phosphate-buffered saline (PBS solution with or without 50 μM ascorbate (Asc. Our results show that the urban PM generally generates much more HOOH than the rural PM but that there is no apparent seasonal difference in HOOH generation. In nearly all of the samples the addition of a physiologically relevant concentration of Asc greatly enhances HOOH formation, but a few of the coarse PM samples were able to generate a considerable amount of HOOH in the absence of added Asc, indicating the presence of unknown reductants. Normalized by air volume, the fine PM (PM2.5 generally makes more HOOH than the corresponding coarse PM (PMcf, i.e., 2.5 to 10 μm, primarily because the mass concentration of PM2.5 is much higher than that of PMcf. However, normalized by PM mass, the coarse PM typically generates more HOOH than the fine PM. The amount of HOOH produced by SJV PM is reduced on average by (78 ± 15% when the transition metal chelator desferoxamine (DSF is added to the extraction solution, indicating that transition metals play a dominant role in HOOH

  15. Acoustically induced optical second harmonic generation in hydrogenated amorphous silicon films

    CERN Document Server

    Ebothe, J; Cabarrocas, P R I; Godet, C; Equer, B

    2003-01-01

    Acoustically induced second harmonic generation (AISHG) in hydrogenated amorphous silicon (a-Si : H) films of different morphology has been observed. We have found that with increasing acoustical power, the optical SHG of Gd : YAB laser light (lambda = 2.03 mu m) increases and reaches its maximum value at an acoustical power density of about 2.10 W cm sup - sup 2. With decreasing temperature, the AISHG signal strongly increases below 48 K and correlates well with the temperature behaviour of differential scanning calorimetry indicating near-surface temperature phase transition. The AISHG maxima were observed at acoustical frequencies of 10-11, 14-16, 20-22 and 23-26 kHz. The independently performed measurements of the acoustically induced IR spectra have shown that the origin of the observed phenomenon is the acoustically induced electron-phonon anharmonicity in samples of different morphology.

  16. Entropy generation minimization for a packed bed reactor in nuclear hydrogen production

    International Nuclear Information System (INIS)

    The thermochemical copper-chlorine (Cu-Cl) cycle is a promising method to produce hydrogen with nuclear energy. In this paper, the fluid flow and heat transfer processes are examined for a packed bed chemical reactor in the Cu-Cl cycle. The heat transfer rate is predicted by a heat-momentum analogy for external flow over a particle, using the friction factor and Reynolds number. The Nusselt number correlation compares well against three prior methods to predict the Nusselt number in a packed bed (for various combinations of the void fraction, Reynolds and Prandtl numbers). The analysis is extended to minimize the entropy generation due to heat transfer and fluid flow irreversibilities in the packed bed reactor. (author)

  17. An Innovative Test Platform for Hydrogen Production and Zero Emission Power Generation from Coal

    International Nuclear Information System (INIS)

    The ZECOMIX project, conceived by ENEA in the framework of Italian National Hydrogen Project, is aimed at studying an integrated process that produces both hydrogen and electricity from coal, with zero emissions and very high efficiency. The key element is the integration of a gasification process, characterized by coal hydro-gasification technology and carbon dioxide sequestration, with the power island, where an oxy-combustion occurs. Many optimization analysis and simulations have been carried out demonstrating the possibility to achieve very high net efficiencies (higher than 50% LHV) and very low (quasi-zero) emissions. The project schedule consists of the design, already started, the construction and the operation of an experimental facility finalized to demonstrate the feasibility of the described reference process. The facility will be realized in the ENEA Research Center of Casaccia, near Rome. It consists of a very flexible plant, in which more components can be tested separately or connected together. The plant is provided with a 50 kg/h coal atmospheric fluid bed gasifier, a fluid bed decarbonator/calcinator reactor filled with calcium oxide pellets, a pressurized hydro-gasifier reactor characterized by a pressure variable from 30 to 100 bar, a 100 kWe micro-turbine test bench, with the combustor chamber modified because of de-carbonized syngas fuelling and finally an oxygen/hydrogen combustor test bench, for experimental activities about the definition of stability limits, operative conditions (dilution, temperature pattern, chemicals) and combustion control. Other auxiliary components are mixing station for hydrogen-based syngas production, and an ordinary steam generator. The first part of the research project is aimed at testing the single component, in particular the main preliminary design criteria adopted for hydro-gasification reactor and carbonator reactor are presented in this paper. The second part of the Project is focused on the integration

  18. Gold nanocluster-sensitized TiO2 nanotubes to enhance the photocatalytic hydrogen generation under visible light

    Science.gov (United States)

    Wang, Hongkai; Chen, Fuyi; Li, Weiyin; Tian, Tian

    2015-08-01

    The wide band-gap of TiO2 semiconductors hinders the photocatalytic hydrogen generation under visible light. In this research, we introduce glutathione-protected gold (Au-GSH) nanoclusters as a sensitizer to extend the active region of TiO2 up to a wavelength of 510 nm under visible light spectrum. We demonstrate that Au-GSH nanoclusters are capable of enhancing photocatalytic effects for hydrogen generation in photo-electrochemical cells (PECs). The combined effects of metal nanoclusters and sacrificial agent (EDTA) enhance the photocurrent up to six times more than what can be achieved using Au-GSH nanoclusters without EDTA. Moreover, the mechanisms of interaction between Au-GSH nanoclusters and EDTA have been investigated through instantaneous photoresponse measurements. A single electrode system has been designed to simplify PECs for hydrogen generation, which exhibits the same enhanced photocatalytic effect.

  19. Hydrogen production in early generation fusion power plant and its socio-economic implication

    International Nuclear Information System (INIS)

    This paper describes technical possibility of high temperature blanket for the early generation of fusion power plant and its application to hydrogen production. Its anticipated implication and strategy from the socio-economic aspects will be also discussed. Material and energy balances, such as fuel supply and delivery of product energy from fusion plants, as well as waste discharge and accident scenario that lead to environmental impact, are characterized by blanket concepts. Thus blankets are considered to dominate the feature of fusion energy that should respond to the requirements of the sponsors, i.e., public and future market. Fusion blanket concept based on the combinations of LiPb and SiC materials are regarded as a candidate for ITER/TBM, and at the same time, applied in various DEMO designs encompassing high temperature output. Recent developments of SiC-LiPb blanket in Japan, EU, US or China suggests staged development paths starting from TBMs and targeting high temperature blanket and efficient energy output from early generation plants. These strategies are strongly affected by the views of these parties on fusion energy, from the aspects of socio-economics. Hydrogen production process with the high temperature blanket is one of the most important issues, because temperature range much higher than is possible with current or near future fission plants are needed, suggesting market possibility different from that of fission. Fuel cycles, particularly lithium supply and TBR control will be also important. Self-sustained fusion fuel cycle requires technical capability to maintain the lithium contents. Liquid blanket has an advantage in continuous and real-time control TBR in a plant, but large amount of lithium-6 and initial tritium supply remains as issues. As for the environmental effect, normal operation release, assumed accidental scenario, and rad-waste will be the key issue to dominate social acceptance of fusion. (author)

  20. Evaluation Of Methods To Measure Hydrogen Generation Rate In A Shielded Cell Environment And A Method Recommendation

    Energy Technology Data Exchange (ETDEWEB)

    Stone, M. E.

    2012-11-07

    The purpose of this document is to describe the current state of the art for determination of hydrogen generation rates of radioactive slurries and solutions to provide a basis for design, fabrication, testing, and implementation of a measurement method for Hydrogen Generation Rate (HGR) during qualification of waste feeds for the Hanford Waste Treatment and Immobilization Plant (WTP). The HGR measurement will be performed on samples of the Low Activity Waste (LAW) and High Level Waste (HLW) staged waste feeds for the WTP as well as on samples from selected unit operations testing during the qualification program. SRNL has performed a review of techniques utilized to measure HGR of high level radioactive waste slurries, evaluated the Hanford 222-S Laboratory method for measurement of hydrogen, and reviewed the hydrogen generation rate models for Hanford waste.Based on the literature review, method evaluation, and SRNL experience with measuring hydrogen generation rate, SRNL recommends that a continuous flow system with online gas analysis be used as the HGR measurement method during waste qualification.

  1. Evaluation Of Methods To Measure Hydrogen Generation Rate In A Shielded Cell Environment And A Method Recommendation

    International Nuclear Information System (INIS)

    The purpose of this document is to describe the current state of the art for determination of hydrogen generation rates of radioactive slurries and solutions to provide a basis for design, fabrication, testing, and implementation of a measurement method for Hydrogen Generation Rate (HGR) during qualification of waste feeds for the Hanford Waste Treatment and Immobilization Plant (WTP). The HGR measurement will be performed on samples of the Low Activity Waste (LAW) and High Level Waste (HLW) staged waste feeds for the WTP as well as on samples from selected unit operations testing during the qualification program. SRNL has performed a review of techniques utilized to measure HGR of high level radioactive waste slurries, evaluated the Hanford 222-S Laboratory method for measurement of hydrogen, and reviewed the hydrogen generation rate models for Hanford waste.Based on the literature review, method evaluation, and SRNL experience with measuring hydrogen generation rate, SRNL recommends that a continuous flow system with online gas analysis be used as the HGR measurement method during waste qualification

  2. Efficient photocatalytic hydrogen generation by silica supported and platinum promoted titanium dioxide

    Energy Technology Data Exchange (ETDEWEB)

    Joshi, Meenal M.; Labhsetwar, Nitin K. [Environmental Materials Division, National Environmental Engineering Research Institute (NEERI, C.S.I.R.), Nagpur 440020 (India); Parwate, D.V. [Rashtrasant Tukadoji Maharaj Nagpur University, Nagpur 440010 (India); Rayalu, Sadhana S., E-mail: s_rayalu@neeri.res.in [Environmental Materials Division, National Environmental Engineering Research Institute (NEERI, C.S.I.R.), Nagpur 440020 (India)

    2013-09-01

    . Hydrogen yield observed is 4791.43 μmol/h/g of TiO{sub 2} and that for P-25 is 161 μmol/h/g of TiO{sub 2} under visible light irradiation. The value is 30 times higher than benchmark material Degussa P-25. This photocatalyst is also found stable up to 24 h without replenishing with sacrificial donor ethanol. However silica gel/TiO{sub 2}/Ru does not show any exciting result for hydrogen generation. The effect of various operating parameters like photocatalyst loading, Illumination time and intensity of light on supported photocatalyst also has been studied.

  3. Hydrogen generation in CSP plants and maintenance of DPO/BP heat transfer fluids - A simulation approach

    Science.gov (United States)

    Kuckelkorn, Thomas; Jung, Christian; Gnädig, Tim; Lang, Christoph; Schall, Christina

    2016-05-01

    The ageing of diphenyl oxide/ biphenyl (DPO/BP) Heat Transfer Fluids (HTFs) implies challenging tasks for operators of parabolic trough power plants in order to find the economic optimum between plant performance and O&M costs. Focusing on the generation of hydrogen, which is effecting from the HTF ageing process, the balance of hydrogen pressure in the HTF is simulated for different operation scenarios. Accelerated build-up of hydrogen pressure in the HTF is causing increased permeation into the annular vacuum space of the installed receivers and must be avoided in order to maintain the performance of these components. Therefore, the effective hydrogen partial pressure in the HTF has to be controlled and limited according to the specified values so that the vacuum lifetime of the receivers and the overall plant performance can be ensured. In order to simulate and visualize the hydrogen balance of a typical parabolic trough plant, initially a simple model is used to calculate the balance of hydrogen in the system and this is described. As input data for the simulation, extrapolated hydrogen generation rates have been used, which were calculated from results of lab tests performed by DLR in Cologne, Germany. Hourly weather data, surface temperatures of the tubing system calculated by using the simulation tool from NREL, and hydrogen permeation rates for stainless steel and carbon steel grades taken from literature have been added to the model. In a first step the effect of HTF ageing, build-up of hydrogen pressure in the HTF and hydrogen loss rates through piping and receiver components have been modeled. In a second step a selective hydrogen removal process has been added to the model. The simulation results are confirming the need of active monitoring and controlling the effective hydrogen partial pressure in parabolic trough solar thermal power plants with DPO/BP HTF. Following the results of the simulation, the expected plant performance can only be achieved

  4. Catalytic hydrolysis of ammonia borane for hydrogen generation using cobalt nanocluster catalyst supported on polydopamine functionalized multiwalled carbon nanotube

    International Nuclear Information System (INIS)

    Hydrogen was generated from ammonia borane complex by hydrolysis using cobalt nanocluster catalyst supported on polydopamine functionalized MWCNTs (multi-walled carbon nanotubes). The impregnation-chemical reduction method was used for the preparation of the supported catalyst. The nanocluster catalyst support was formed by in-situ oxidative polymerization of dopamine on the MWCNTs in alkaline solution at room temperature. The structural and physical–chemical properties of the nanocluster catalyst were characterized by FT-IR (Fourier transform infrared spectroscopy), EDX (energy-dispersive X-ray spectroscopy), SEM (scanning electron microscope), XRD (X-ray diffraction) and TEM (transmission electron microscopy). The nanocluster catalyst showed good catalytic activity for the hydrogen generation from aqueous ammonia borane complex. A reusability test to determine the practical usage of the catalyst was also investigated. The result revealed that the catalyst maintained an appreciable catalytic performance and stability in terms of its reusability after three cycle of reuse for the hydrolysis reaction. Also, the activation energy for the hydrolysis of ammonia borane complex was estimated to be 50.41 kJmol−1, which is lower than the values of some of the reported catalyst. The catalyst can be considered as a promising candidate in developing highly efficient portable hydrogen generation systems such as PEMFC (proton exchange membrane fuel cells). - Highlights: • Co/Pdop-o-MWCNT (Pdop functionalized MWCNT supported cobalt nanocluster) catalyst was synthesized for hydrogen generation. • It is an active catalyst for hydrogen generation via hydrolysis of ammonia borane. • It showed good stability in terms of reusability for the hydrogen generation

  5. An appealing photo-powered multi-functional energy system for the poly-generation of hydrogen and electricity

    Science.gov (United States)

    Tang, Tiantian; Li, Kan; Shen, Zhemin; Sun, Tonghua; Wang, Yalin; Jia, Jinping

    2015-10-01

    This paper focuses on a photo-powered poly-generation system (PPS) that is powered by the photocatalytic oxidation of organic substrate to produce hydrogen energy and electrical energy synchronously. This particular device runs entirely on light energy and chemical energy of substrate without external voltage. The performance measurements and optimization experiments are all investigated by using the low concentration of pure ethanol (EtOH) solution. Compared with the conventional submerged reactor for the photogeneration of hydrogen, the hydrogen and the electric current obtained in the constructed PPS are all relatively stable in experimental period and the numerical values detected are many times higher than that of the former by using various simulated ethanol waste liquid. When using Chinese rice wine as substrate at the same ethanol content level (i.e., 0.1 mol L-1), the production of hydrogen is close to that of the pure ethanol solution in the constructed PPS, but no hydrogen is detected in the conventional submerged reactor. These results demonstrate that the constructed PPS could effectively utilize light energy and perform good capability in poly-generation of hydrogen and electricity.

  6. Sliding discharges in steam: effects of dielectric surface and hydrocarbon additives on hydrogen, oxygen and hydrogen peroxide generation

    International Nuclear Information System (INIS)

    A sliding surface discharge was formed on a dielectric layer in steam at ∼100 °C and atmospheric pressure. The material properties and the thickness of the dielectric layer were found to strongly affect the energy deposition into the plasma. With a 0.32 cm thick dielectric the energy deposition was 1.4 times greater than with a 0.48 cm thick dielectric, and with window glass it was 1.3 times greater than with Macor of the same thickness. Product gases were H2 (73 ± 4%) and O2 (27 ± 1%), and H2O2 accumulated in the condensed water up to 0.4 g l−1. The energy yield for hydrogen was 1.2 ± 0.1 g H2 kWh−1 and independent of the input power and thickness or material of the dielectric. However, for hydrogen peroxide the energy yield, which varied between 0.61 and 3.2 g H2O2 kWh−1, was found to depend strongly on the thickness and material of the dielectric. The addition of benzene to the steam increased the energy efficiency of hydrogen to 2.3 g kWh−1, and decreased oxygen and hydrogen peroxide by about 3 and 6 times, respectively. It also caused the deposition of phenol and polymer-like layers on the dielectric. The results are explained on the basis of reactions of H and OH radicals adsorbed on the surface and/or in gas phase. (paper)

  7. Modulation of Na+/K+ ATPase Activity by Hydrogen Peroxide Generated through Heme in L. amazonensis.

    Directory of Open Access Journals (Sweden)

    Nathália Rocco-Machado

    Full Text Available Leishmania amazonensis is a protozoan parasite that occurs in many areas of Brazil and causes skin lesions. Using this parasite, our group showed the activation of Na+/K+ ATPase through a signaling cascade that involves the presence of heme and protein kinase C (PKC activity. Heme is an important biomolecule that has pro-oxidant activity and signaling capacity. Reactive oxygen species (ROS can act as second messengers, which are required in various signaling cascades. Our goal in this work is to investigate the role of hydrogen peroxide (H2O2 generated in the presence of heme in the Na+/K+ ATPase activity of L. amazonensis. Our results show that increasing concentrations of heme stimulates the production of H2O2 in a dose-dependent manner until a concentration of 2.5 μM heme. To confirm that the effect of heme on the Na+/K+ ATPase is through the generation of H2O2, we measured enzyme activity using increasing concentrations of H2O2 and, as expected, the activity increased in a dose-dependent manner until a concentration of 0.1 μM H2O2. To investigate the role of PKC in this signaling pathway, we observed the production of H2O2 in the presence of its activator phorbol 12-myristate 13-acetate (PMA and its inhibitor calphostin C. Both showed no effect on the generation of H2O2. Furthermore, we found that PKC activity is increased in the presence of H2O2, and that in the presence of calphostin C, H2O2 is unable to activate the Na+/K+ ATPase. 100 μM of Mito-TEMPO was capable of abolishing the stimulatory effect of heme on Na+/K+ ATPase activity, indicating that mitochondria might be the source of the hydrogen peroxide production induced by heme. The modulation of L. amazonensis Na+/K+ ATPase by H2O2 opens new possibilities for understanding the signaling pathways of this parasite.

  8. Modulation of Na+/K+ ATPase Activity by Hydrogen Peroxide Generated through Heme in L. amazonensis.

    Science.gov (United States)

    Rocco-Machado, Nathália; Cosentino-Gomes, Daniela; Meyer-Fernandes, José Roberto

    2015-01-01

    Leishmania amazonensis is a protozoan parasite that occurs in many areas of Brazil and causes skin lesions. Using this parasite, our group showed the activation of Na+/K+ ATPase through a signaling cascade that involves the presence of heme and protein kinase C (PKC) activity. Heme is an important biomolecule that has pro-oxidant activity and signaling capacity. Reactive oxygen species (ROS) can act as second messengers, which are required in various signaling cascades. Our goal in this work is to investigate the role of hydrogen peroxide (H2O2) generated in the presence of heme in the Na+/K+ ATPase activity of L. amazonensis. Our results show that increasing concentrations of heme stimulates the production of H2O2 in a dose-dependent manner until a concentration of 2.5 μM heme. To confirm that the effect of heme on the Na+/K+ ATPase is through the generation of H2O2, we measured enzyme activity using increasing concentrations of H2O2 and, as expected, the activity increased in a dose-dependent manner until a concentration of 0.1 μM H2O2. To investigate the role of PKC in this signaling pathway, we observed the production of H2O2 in the presence of its activator phorbol 12-myristate 13-acetate (PMA) and its inhibitor calphostin C. Both showed no effect on the generation of H2O2. Furthermore, we found that PKC activity is increased in the presence of H2O2, and that in the presence of calphostin C, H2O2 is unable to activate the Na+/K+ ATPase. 100 μM of Mito-TEMPO was capable of abolishing the stimulatory effect of heme on Na+/K+ ATPase activity, indicating that mitochondria might be the source of the hydrogen peroxide production induced by heme. The modulation of L. amazonensis Na+/K+ ATPase by H2O2 opens new possibilities for understanding the signaling pathways of this parasite. PMID:26070143

  9. Generation of Hydrogen, Lignin and Sodium Hydroxide from Pulping Black Liquor by Electrolysis

    Directory of Open Access Journals (Sweden)

    Guangzai Nong

    2015-12-01

    Full Text Available Black liquor is generated in Kraft pulping of wood or non-wood raw material in pulp mills, and regarded as a renewable resource. The objective of this paper was to develop an effective means to remove the water pollutants by recovery of both lignin and sodium hydroxide from black liquor, based on electrolysis. The treatment of a 1000 mL of black liquor (122 g/L solid contents consumed 345.6 kJ of electric energy, and led to the generation of 30.7 g of sodium hydroxide, 0.82 g of hydrogen gas and 52.1 g of biomass solids. Therefore, the recovery ratios of elemental sodium and biomass solids are 80.4% and 76%, respectively. Treating black liquor by electrolysis is an environmentally friendly technology that can, in particular, be an alternative process in addressing the environmental issues of pulping waste liquor to the small-scale mills without black liquor recovery.

  10. The origin of enantioselectivity in the l-threonine-derived phosphine-sulfonamide catalyzed aza-Morita-Baylis-Hillman reaction: Effects of the intramolecular hydrogen bonding

    KAUST Repository

    Lee, Richmond

    2013-01-01

    l-Threonine-derived phosphine-sulfonamide 4 was identified as the most efficient catalyst to promote enantioselective aza-Morita-Baylis-Hillman (MBH) reactions, affording the desired aza-MBH adducts with excellent enantioselectivities. Density functional theory (DFT) studies were carried out to elucidate the origin of the observed enantioselectivity. The importance of the intramolecular N-H⋯O hydrogen-bonding interaction between the sulfonamide and enolate groups was identified to be crucial in inducing a high degree of stereochemical control in both the enolate addition to imine and the subsequent proton transfer step, affording aza-MBH reactions with excellent enantioselectivity. © 2013 The Royal Society of Chemistry.

  11. A Metallacycle Fragmentation Strategy for Vinyl Transfer from Enol Carboxylates to Secondary Alcohol C-H Bonds via Osmium- or Ruthenium-Catalyzed Transfer Hydrogenation.

    Science.gov (United States)

    Park, Boyoung Y; Luong, Tom; Sato, Hiroki; Krische, Michael J

    2015-06-24

    A strategy for catalytic vinyl transfer from enol carboxylates to activated secondary alcohol C-H bonds is described. Using XPhos-modified ruthenium(0) or osmium(0) complexes, enol carboxylate-carbonyl oxidative coupling forms transient β-acyloxy-oxametallacycles, which eliminate carboxylate to deliver allylic ruthenium(II) or osmium(II) alkoxides. Reduction of the metal(II) salt via hydrogen transfer from the secondary alcohol reactant releases the product of carbinol C-H vinylation and regenerates ketone and zero-valent catalyst. PMID:26066660

  12. Research progress on ionic plasmas generated in an intense hydrogen negative ion source

    Energy Technology Data Exchange (ETDEWEB)

    Takeiri, Y., E-mail: takeiri@nifs.ac.jp; Tsumori, K.; Nagaoka, K.; Kaneko, O. [National Institute for Fusion Science, Toki 509-5292 (Japan); School of Physical Sciences, The Graduate University for Advanced Studies, Toki 509-5292 (Japan); Ikeda, K.; Nakano, H.; Kisaki, M.; Tokuzawa, T.; Osakabe, M.; Kondo, T.; Sato, M.; Shibuya, M.; Komada, S.; Sekiguchi, H. [National Institute for Fusion Science, Toki 509-5292 (Japan); Geng, S. [School of Physical Sciences, The Graduate University for Advanced Studies, Toki 509-5292 (Japan)

    2015-04-08

    Characteristics of ionic plasmas, observed in a high-density hydrogen negative ion source, are investigated with a multi-diagnostics system. The ionic plasma, which consists of hydrogen positive- and negative-ions with a significantly low-density of electrons, is generated in the ion extraction region, from which the negative ions are extracted through the plasma grid. The negative ion density, i.e., the ionic plasma density, as high as the order of 1×10{sup 17}m{sup −3}, is measured with cavity ring-down spectroscopy, while the electron density is lower than 1×10{sup 16}m{sup −3}, which is confirmed with millimeter-wave interferometer. Reduction of the negative ion density is observed at the negative ion extraction, and at that time the electron flow into the ionic plasma region is observed to conserve the charge neutrality. Distribution of the plasma potential is measured in the extraction region in the direction normal to the plasma grid surface with a Langmuir probe, and the results suggest that the sheath is formed at the plasma boundary to the plasma grid to which the bias voltage is applied. The beam extraction should drive the negative ion transport in the ionic plasma across the sheath formed on the extraction surface. Larger reduction of the negative ions at the beam extraction is observed in a region above the extraction aperture on the plasma grid, which is confirmed with 2D image measurement of the Hα emission and cavity ring-down spectroscopy. The electron distribution is also measured near the plasma grid surface. These various properties observed in the ionic plasma are discussed.

  13. Study of the acceleration of ammonia generation process from poultry residues aiming at hydrogen production

    International Nuclear Information System (INIS)

    environment. The possibility of ammonia emission increment observed in this study, and its use in a system of ammonia generation - hydrogen production - fuel cell might produce electricity in the enterprise, reducing the expenses of the farms and providing a properly destination for these residues. (author)

  14. Investigation of advanced nanostructured multijunction photoanodes for enhanced solar hydrogen generation via water splitting

    Science.gov (United States)

    Ishihara, Hidetaka

    As the worldwide demand for fossil-based fuel increases every day and the fossil reserve continues to be depleted, the need for alternative/renewable energy sources has gained momentum. Electric, hybrid, and hydrogen cars have been at the center of discussion lately among consumers, automobile manufacturers, and politicians, alike. The development of a fuel-cell based engine using hydrogen has been an ambitious research area over the last few decades-ever since Fujishima showed that hydrogen can be generated via the solar-energy driven photo-electrolytic splitting of water. Such solar cells are known as Photo-Electro-Chemical (PEC) solar cells. In order to commercialize this technology, various challenges associated with photo-conversion efficiency, chemical corrosion resistance, and longevity need to be overcome. In general, metal oxide semiconductors such as titanium dioxide (TiO 2, titania) are excellent candidates for PEC solar cells. Titania nanotubes have several advantages, including biocompatibility and higher chemical stability. Nevertheless, they can absorb only 5-7% of the solar spectrum which makes it difficult to achieve the higher photo-conversion efficiency required for successful commercial applications. A two-prong approach was employed to enhance photo-conversion efficiency: 1) surface modification of titania nanotubes using plasma treatment and 2) nano-capping of the titania nanotubes using titanium disilicide. The plasma surface treatment with N2 was found to improve the photo-current efficiency of titania nanotubes by 55%. Similarly, a facile, novel approach of nano-capping titania nanotubes to enhance their photocurrent response was also investigated. Electrochemically anodized titania nanotubes were capped by coating a 25 nm layer of titanium disilicide using RF magnetron sputtering technique. The optical properties of titania nanotubes were not found to change due to the capping; however, a considerable increase (40%) in the photocurrent

  15. Three distinct hydrogen sensing responses of palladium line patterns generated by femtosecond laser direct writing

    International Nuclear Information System (INIS)

    Application of a palladium nanostructure in hydrogen detection is a focus of current research due to its high sensitivity. In this paper, palladium nanometre films are fabricated using femtosecond laser decomposition of palladium acetate films. Their hydrogen sensing characteristics are studied as a function of hydrogen concentration and morphologies of palladium films. As palladium film morphologies vary from continuous to partially continuous and then to discontinuous, the corresponding hydrogen response changes from normal to pulse-like and then to switch-like. Their response characteristics are determined by the different combined effects of the formation of high-resistance palladium hydrogen and the corresponding narrowing of nanogaps between palladium nanoparticles. (paper)

  16. Hydrogen Isotope Measurements of Organic Acids and Alcohols by Pyrolysis-GC-MS-TC-IRMS: Application to Analysis of Experimentally Derived Hydrothermal Mineral-Catalyzed Organic Products

    Science.gov (United States)

    Socki, Richard A.; Fu, Qi; Niles, Paul B.; Gibson, Everett K., Jr.

    2012-01-01

    We report results of experiments to measure the H isotope composition of organic acids and alcohols. These experiments make use of a pyroprobe interfaced with a GC and high temperature extraction furnace to make quantitative H isotope measurements. This work compliments our previous work that focused on the extraction and analysis of C isotopes from the same compounds [1]. Together with our carbon isotope analyses our experiments serve as a "proof of concept" for making C and H isotope measurements on more complex mixtures of organic compounds on mineral surfaces in abiotic hydrocarbon formation processes at elevated temperatures and pressures. Our motivation for undertaking this work stems from observations of methane detected within the Martian atmosphere [2-5], coupled with evidence showing extensive water-rock interaction during Mars history [6-8]. Methane production on Mars could be the result of synthesis by mineral surface-catalyzed reduction of CO2 and/or CO by Fischer-Tropsch Type (FTT) reactions during serpentization [9,10]. Others have conducted experimental studies to show that FTT reactions are plausible mechanisms for low-molecular weight hydrocarbon formation in hydrothermal systems at mid-ocean ridges [11-13]. Our H isotope measurements utilize an analytical technique combining Pyrolysis-Gas Chromatograph-Mass Spectrometry-High Temperature Conversion-Isotope Ratio Mass Spectrometry (Py-GC-MS-TC-IRMS). This technique is designed to carry a split of the pyrolyzed GC-separated product to a Thermo DSQII quadrupole mass spectrometer as a means of making qualitative and semi-quantitative compositional measurements of separated organic compounds, therefore both chemical and isotopic measurements can be carried out simultaneously on the same sample.

  17. Degradation of 2,4,6-Trichlorophenol Using Hydrogen Peroxide Catalyzed by Nanoscale Zero-Valent Iron Supported on Ion Exchange Resin.

    Science.gov (United States)

    Tai, Chao; She, Jiaping; Yin, Yongguang; Zhao, Tongqian; Wu, Li

    2016-06-01

    Nanoscale zero-valent iron (NZVI) supported on ion exchange resin was prepared and characterized by scanning electron microscope and energy dispersive spectroscopy, with a simple model developed for describing the catalyst. The degradation of 2,4,6-trichlorophenol (2,4,6-TCP) by hydrogen peroxide using NZVI supported on ion exchange resin as the catalyst, was studied. The results showed that 2,4,6-TCP with a concentration of 1 mmol L(-1) could be well degraded into low molecule weight organic acids in two hours. The optimized condition was as follows: pH, 3.0; temperature, 35 degrees C; catalyst dosage, 1.5 g; and hydrogen peroxide, 0.16 mmol L(-1). The catalyst has good reusability, with no catalytic efficiency decreasing even after ten times recycles. A possible mechanism of 2,4,6-TCP degradation was proposed, based on the products indentified by GC-MS after derived using trimethylsulfonium hydroxide. PMID:27427643

  18. Photoelectrocatalytic hydrogen generation and simultaneous degradation of organic pollutant via CdSe/TiO2 nanotube arrays

    Science.gov (United States)

    Wang, Wenchao; Li, Fang; Zhang, Dieqing; Leung, Dennis Y. C.; Li, Guisheng

    2016-01-01

    CdSe nanoparticles enhanced TiO2 nanotube arrays electrodes (CdSe/TNTAs) were explored as the photoanode for driving the photoelectrocatalytic (PEC) generation of hydrogen and simultaneous degradation of organic pollutants in a PEC system. The evolution hydrogen and the simultaneous degradation of organic pollutants were performed in an electrolytic cell (three electrodes system) under visible-light (λ > 400 nm). Such CdSe/TiO2 based PEC system exhibited both high efficiency of hydrogen generation and effective oxidation of methyl orange (MO). Such high PEC performance of CdSe/TNTAs was attributed to the high dispersity of CdSe nanoparticles on both outside and inside of the pore walls of TiO2 nanotube arrays, the strong combination and heterojunctions between CdSe and TiO2 through Cdsbnd O bonds via electrodeposition with ion-exchange method.

  19. Hydrogen system (hydrogen fuels feasibility)

    International Nuclear Information System (INIS)

    This feasibility study on the production and use of hydrogen fuels for industry and domestic purposes includes the following aspects: physical and chemical properties of hydrogen; production methods steam reforming of natural gas, hydrolysis of water; liquid and gaseous hydrogen transportation and storage (hydrogen-hydride technology); environmental impacts, safety and economics of hydrogen fuel cells for power generation and hydrogen automotive fuels; relevant international research programs

  20. Fractal disperse hydrogen sorption kinetics in spark discharge generated Mg/NbOx and Mg/Pd nanocomposites

    NARCIS (Netherlands)

    Anastasopol, A.; Pfeiffer, T.V.; Schmidt-Ott, A.; Mulder, F.M.; Eijt, S.W.H.

    2011-01-01

    Isothermal hydrogen desorption of spark discharge generated Mg/NbOx and Mg/Pd metal hydride nanocomposites is consistently described by a kinetic model based on multiple reaction rates, in contrast to the Johnson-Mehl-Avrami-Kolmogorov [M. Avrami, J. Phys. Chem. 9, 177 (1941); W. A. Johnson and R. F

  1. Generation of core–shell nanoparticles Al@Ti by laser ablation in liquid for hydrogen storage

    International Nuclear Information System (INIS)

    Highlights: • Core–shell Al@Ti NPs are generated by laser ablation in isopropanol. • Isopropanol was saturated with molecular hydrogen. • The composite metallic Al-Ti target was used. • HR TEM characterization shows that Ti core is covered by epitaxial Al shell. • Al@Ti NPs are promising for hydrogen storage. - Abstract: Core–shell Al@Ti nanoparticles are generated by ablation of a composite Ti–Al target in liquid isopropanol saturated with molecular hydrogen using a Nd:YAG laser with pulse duration of 10 ps and repetition rate of 200 kHz. The target is made of two plates of corresponding metals stacked together and placed into a flowing cell reactor. Transmission Electron Microscopy analysis of generated NPs reveals their core–shell structure with Ti core and Al shell. Average size of NPs determined by means of measuring disk centrifuge is around 40 nm. Saturation of NPs by hydrogen is due to sharp dependence of its solubility in these metals on temperature. XRD studies of generated NPs show the peaks of both metallic Ti and Al with some amount of TiO2. No peaks of Ti–Al alloys are observed

  2. Maintaining a Technology-Neutral Approach to Hydrogen Production Process Development through Conceptual Design of the Next Generation Nuclear Plant

    International Nuclear Information System (INIS)

    The Next Generation Nuclear Plant (NGNP) project was authorized in the Energy Policy Act of 2005 (EPAct), tasking the U.S. Department of Energy (DOE) with demonstrating High Temperature Gas-Cooled Reactor (HTGR) technology. The demonstration is to include the technical, licensing, operational, and commercial viability of HTGR technology for the production of electricity and hydrogen. The Nuclear Hydrogen Initiative (NHI), a component of the DOE Hydrogen Program managed by the Office of Nuclear Energy, is also investigating multiple approaches to cost effective hydrogen production from nuclear energy. The objective of NHI is development of the technology and information basis for a future decision on commercial viability. The initiatives are clearly intertwined. While the objectives of NGNP and NHI are generally consistent, NGNP has progressed to the project definition phase and the project plan has matured. Multiple process applications for the NGNP require process heat, electricity and hydrogen in varied combinations and sizes. Coupling these processes to the reactor in multiple configurations adds complexity to the design, licensing and demonstration of both the reactor and the hydrogen production process. Commercial viability of hydrogen production may depend on the specific application and heat transport configuration. A component test facility (CTF) is planned by the NGNP to support testing and demonstration of NGNP systems, including those for hydrogen production, in multiple configurations. Engineering-scale demonstrations in the CTF are expected to start in 2012 to support scheduled design and licensing activities leading to subsequent construction and operation. Engineering-scale demonstrations planned by NHI are expected to start at least two years later. Reconciliation of these schedules is recommended to successfully complete both initiatives. Hence, closer and earlier integration of hydrogen process development and heat transport systems is sensible

  3. Analysis and control of an in situ hydrogen generation and fuel cell power system for automotive applications

    Science.gov (United States)

    Kolavennu, Panini K.

    A new future in automotive transportation is approaching where vehicles are powered by new, clean and efficient energy sources. While different technologies will contribute to this future, many see fuel cells as the leading long term candidate for becoming the power source for emissions-free, mass produced light vehicles. The development of emissions-free vehicles, which run directly on hydrogen, is the true long term goal. However significant difficulties exist in developing these vehicles, due to hydrogen storage problems. For automotive applications, it is desirable to use a carbon-based hydrogenous fuel. The focus of this research was to analyze a fuel cell system for automotive applications, which generated hydrogen in situ using methane as a fuel source. This system consists of four parts: (1) an in situ hydrogen generation subsystem, (2) a power generation subsystem, (3) a thermal management subsystem and (4) a switching control subsystem. The novelty of this research lies in the fact that the entire system was considered from a systems engineering viewpoint with realistic constraints. A fuel processor subsystem was designed and its volume optimized to less than 100 liters. A relationship between the fuel fed into the fuel processor and the hydrogen coming out of it was developed. Using a fuel cell model an overall relationship between the fuel feed rate and the power output was established. The fuel cell car must be fully operational within a minute or so of a cold-start and must respond to rapidly varying loads. Significant load transitions occur frequently as a result of changes in driving conditions. These engineering constraints were addressed by coupling a battery to the fuel cell. A switching controller was designed and it was validated using realistic power profiles. Finally, a model reference adaptive controller was designed to handle nonlinearities and load transitions. The adaptive controller performance was enhanced by adding dead zone

  4. Development of novel spinel-type photocatalysts for hydrogen generation by solar energy conversion

    International Nuclear Information System (INIS)

    Two spinel-type oxide semiconductors InGaZnO4 and BaCr2O4 crystallized in rhombohedral and orthorhombic structures, respectively, have been developed as photocatalysts for hydrogen generation. The crystal structure was determined by powder X-ray diffraction. The photo-absorption property was measured with an UV-vis spectrometer. Photocatalytic activities of Pt or NiOx loaded powder photocatalyst were evaluated by H2 evolution from aqueous CH3OH solution or pure water under UV and/or visible light irradiation. It was found that: (1) Pt or NiOx loaded InGaZnO4 exhibited substantial activity of H2 evolution from aqueous CH3OH solution or pure water under UV light irradiation. (2) In BaCr2O4, the internal photo-excitation of electrons from the split Cr3d-t2g orbit to Cr3d-eg orbit was supposed to play an important role in the photocatalytic H2 evolution under visible light irradiation. (orig.)

  5. CdSe-sensitized branched CdS hierarchical nanostructures for efficient photoelectrochemical solar hydrogen generation.

    Science.gov (United States)

    Han, Zonghu; Wang, Meng; Chen, Xiangyan; Shen, Shaohua

    2016-04-20

    A two-step hydrothermal process was used to synthesize branched CdS hierarchical nanostructures, which were then sensitized by CdSe via a chemical bath deposition method. CdS nanorods grew on the surface of the existing CdS nanorods to form hierarchical assemblies. After the chemical bath deposition process, core-shell structures of branched CdS nanorods covered by a uniform CdSe overlayer were formed. The branched hierarchical nanostructure improved the optical absorption by increasing the optical path via additional light trapping, as well as increasing the contact area between the electrode and electrolyte for more reactive sites, contributing to the higher photoelectrochemical performance than that obtained for the rod-like nanostructures. After CdSe sensitization, with the optical absorption greatly extended to longer wavelengths and the photoexcited charge carriers efficiently separated at the type II CdS/CdSe interface, the branched CdS/CdSe hierarchical nanostructures showed considerably increased photoelectrochemical performance compared with the CdS/CdSe nanorods, with a photoconversion efficiency for solar hydrogen generation of 2.7%. PMID:27058590

  6. Silicon decorated with amorphous cobalt molybdenum sulfide catalyst as an efficient photocathode for solar hydrogen generation.

    Science.gov (United States)

    Chen, Yang; Tran, Phong D; Boix, Pablo; Ren, Yi; Chiam, Sing Yang; Li, Zhen; Fu, Kunwu; Wong, Lydia H; Barber, James

    2015-04-28

    The construction of viable photoelectrochemical (PEC) devices for solar-driven water splitting can be achieved by first identifying an efficient independent photoanode for water oxidation and a photocathode for hydrogen generation. These two photoelectrodes then must be assembled with a proton exchange membrane within a complete coupled system. Here we report the preparation of a Si/a-CoMoSx hybrid photocathode which shows impressive performance (onset potential of 0.25 V vs RHE and photocurrent jsc of 17.5 mA cm(-2) at 0 V vs RHE) in pH 4.25 phosphate solution and under simulated AM 1.5 solar illumination. This performance is among the best reported for Si photocathodes decorated with noble-metal-free catalysts. The electrode preparation is scalable because it relies on a photoassisted electrodeposition process employing an available p-type Si electrode and [Co(MoS4)2](2-) precursor. Investigation of the mechanism of the Si/a-CoMoSx electrode revealed that under conditions of H2 photogeneration this bimetallic sulfide catalyst is highly efficient in extracting electrons from illuminated Si and subsequently in reducing protons into H2. The Si/a-CoMoSx photocathode is functional over a wide range of pH values, thus making it a promising candidate for the construction of a complete solar-driven water splitting PEC device. PMID:25801437

  7. Minimum Entropy Generation Theorem Investigation and Optimization of Metal Hydride Alloy Hydrogen Storage

    Directory of Open Access Journals (Sweden)

    Chi-Chang Wang

    2014-05-01

    Full Text Available The main purpose of this paper is to carry out numerical simulation of the hydrogen storage on exothermic reaction of metal hydride LaNi5 alloy container. In addition to accelerating the reaction speed of the internal metal hydride by internal control tube water-cooled mode, analyze via the application of second law of thermodynamics the principle of entropy generation. Use COMSOL Mutilphysics 4.3 a to engage in finite element method value simulation on two-dimensional axisymmetric model. Also on the premise that the internal control tube parameters the radius ri, the flow rate U meet the metal hydride saturation time, observe the reaction process of two parameters on the tank, entropy distribution and the results of the accumulated entropy. And try to find the internal tube parameter values of the minimum entropy, whose purpose is to be able to identify the reaction process and the reaction results of internal tank’s optimum energy conservation.

  8. Design and Control of Integrated Systems for Hydrogen Production and Power Generation

    Science.gov (United States)

    Georgis, Dimitrios

    Growing concerns on CO2 emissions have led to the development of highly efficient power plants. Options for increased energy efficiencies include alternative energy conversion pathways, energy integration and process intensification. Solid oxide fuel cells (SOFC) constitute a promising alternative for power generation since they convert the chemical energy electrochemically directly to electricity. Their high operating temperature shows potential for energy integration with energy intensive units (e.g. steam reforming reactors). Although energy integration is an essential tool for increased efficiencies, it leads to highly complex process schemes with rich dynamic behavior, which are challenging to control. Furthermore, the use of process intensification for increased energy efficiency imposes an additional control challenge. This dissertation identifies and proposes solutions on design, operational and control challenges of integrated systems for hydrogen production and power generation. Initially, a study on energy integrated SOFC systems is presented. Design alternatives are identified, control strategies are proposed for each alternative and their validity is evaluated under different operational scenarios. The operational range of the proposed control strategies is also analyzed. Next, thermal management of water gas shift membrane reactors, which are a typical application of process intensification, is considered. Design and operational objectives are identified and a control strategy is proposed employing advanced control algorithms. The performance of the proposed control strategy is evaluated and compared with classical control strategies. Finally SOFC systems for combined heat and power applications are considered. Multiple recycle loops are placed to increase design flexibility. Different operational objectives are identified and a nonlinear optimization problem is formulated. Optimal designs are obtained and their features are discussed and compared

  9. Analysis of the dynamics of hydrogen ingress to secondary sodium after the replacement of the steam generator stages of the BN-600 power unit

    International Nuclear Information System (INIS)

    The article presents the calculation methodology of hydrogen ingress rate into secondary circuit sodium of the BN-600 power unit. The sources and the mechanism of the hydrogen ingress after the replacement of a lot of the PGN-200M steam generator stages within the scope of work on the power unit operation lifetime extension were defined. The hydrogen ingress rate after impending replacements of steam generator stages was estimated

  10. Technical and economic analyses of a hydrogen-fed gas turbine with steam injection and co-generation

    International Nuclear Information System (INIS)

    Enel has been working on a hydrogen programme dealing with both hydrogen production and uses. The first phase deals with a hydrogen-fed, gas turbine-based co-generative cycle, in which steam injection in the gas turbine itself is adopted in order to couple high process efficiencies with very low nitrous oxide emissions. This paper presents the main results of the co-generative cycle thermodynamic analysis and focuses on the plant economic evaluations under different economic and regulatory scenarios. Results show that hydrogen can be used very effectively in this kind of plant, where electricity efficiency can reach 40% and global co-generation efficiencies can also exceed 90% in relatively small-scale power plants. However, the very high specific investment costs associated with small plants require promotion policies to be applied in order to allow profitable investments. In the future, this kind of plant could provide densely populated areas with electricity and heat with no additional side-effects on the environment. (author)

  11. Hydrogen generation during melter feed preparation of Tank 42 sludge and salt washed loaded CST in the Defense Waste Processing Facility

    International Nuclear Information System (INIS)

    The main objective of these scoping tests was to measure the rate of hydrogen generation in a series of experiments designed to duplicate the expected SRAT and SME processing conditions in laboratory scale vessels. This document details the testing performed to determine the maximum hydrogen generation expected with a coupled flowsheet of sludge, loaded CST [crystalline silicotitanate], and frit

  12. Hydrogen generation during melter feed preparation of Tank 42 sludge and salt washed loaded CST in the Defense Waste Processing Facility

    Energy Technology Data Exchange (ETDEWEB)

    Daniel, W.E.

    1999-12-08

    The main objective of these scoping tests was to measure the rate of hydrogen generation in a series of experiments designed to duplicate the expected SRAT and SME processing conditions in laboratory scale vessels. This document details the testing performed to determine the maximum hydrogen generation expected with a coupled flowsheet of sludge, loaded CST [crystalline silicotitanate], and frit.

  13. Second generation biofuels, an accelerator of the transition toward an economy driven by energy drawn from hydrogen

    International Nuclear Information System (INIS)

    The growth of the bio economy, especially in transportation, involves developing a bio-fuel industry. First generation bio-fuels were produced from plant sugars like starch or from plant oils. Second generation bio fuels use as raw materials the whole plant and especially agricultural and forestry wastes which extend the resource considerably and limit the competition between food use and fuel use. Second generation bio-fuels can be made with not only biological methods but also biomass-to-liquid processes borrowed from thermochemistry. Players in this field, including 'Air Liquide' company, are drawing up a technical and economic road-map for competitiveness in this emerging branch of industry. Since the thermochemical approach for gasifying a biomass also yields large quantities of hydrogen, the industrialization of this branch and concomitant production of bio-hydrogen at competitive prices provide leverage for accelerating the transition toward using H2 for transportation

  14. Polymer membrane based electrolytic cell and process for the direct generation of hydrogen peroxide in liquid streams

    Science.gov (United States)

    White, James H. (Inventor); Schwartz, Michael (Inventor); Sammells, Anthony F. (Inventor)

    1997-01-01

    An electrolytic cell for generating hydrogen peroxide is provided including a cathode containing a catalyst for the reduction of oxygen, and an anode containing a catalyst for the oxidation of water. A polymer membrane, semipermeable to either protons or hydroxide ions is also included and has a first face interfacing to the cathode and a second face interfacing to the anode so that when a stream of water containing dissolved oxygen or oxygen bubbles is passed over the cathode and a stream of water is passed over the anode, and an electric current is passed between the anode and the cathode, hydrogen peroxide is generated at the cathode and oxygen is generated at the anode.

  15. Kinetics and mechanisms of the oxidation of alcohols and hydroxylamines by hydrogen peroxide, catalyzed by methyltrioxorhenium, MTO, and the oxygen binding properties of cobalt Schiff base complexes

    Energy Technology Data Exchange (ETDEWEB)

    Zauche, Timothy

    1999-02-12

    Catalysis is a very interesting area of chemistry, which is currently developing at a rapid pace. A great deal of effort is being put forth by both industry and academia to make reactions faster and more productive. One method of accomplishing this is by the development of catalysts. Enzymes are an example of catalysts that are able to perform reactions on a very rapid time scale and also very specifically; a goal for every man-made catalyst. A kinetic study can also be carried out for a reaction to gain a better understanding of its mechanism and to determine what type of catalyst would assist the reaction. Kinetic studies can also help determine other factors, such as the shelf life of a chemical, or the optimum temperature for an industrial scale reaction. An area of catalysis being studied at this time is that of oxygenations. Life on this earth depends on the kinetic barriers for oxygen in its various forms. If it were not for these barriers, molecular oxygen, water, and the oxygenated materials in the land would be in a constant equilibrium. These same barriers must be overcome when performing oxygenation reactions on the laboratory or industrial scale. By performing kinetic studies and developing catalysts for these reactions, a large number of reactions can be made more economical, while making less unwanted byproducts. For this dissertation the activation by transition metal complexes of hydrogen peroxide or molecular oxygen coordination will be discussed.

  16. Evaluation of Hybrid Power Plants using Biomass, Photovoltaics and Steam Electrolysis for Hydrogen and Power Generation

    Science.gov (United States)

    Petrakopoulou, F.; Sanz, J.

    2014-12-01

    Steam electrolysis is a promising process of large-scale centralized hydrogen production, while it is also considered an excellent option for the efficient use of renewable solar and geothermal energy resources. This work studies the operation of an intermediate temperature steam electrolyzer (ITSE) and its incorporation into hybrid power plants that include biomass combustion and photovoltaic panels (PV). The plants generate both electricity and hydrogen. The reference -biomass- power plant and four variations of a hybrid biomass-PV incorporating the reference biomass plant and the ITSE are simulated and evaluated using exergetic analysis. The variations of the hybrid power plants are associated with (1) the air recirculation from the electrolyzer to the biomass power plant, (2) the elimination of the sweep gas of the electrolyzer, (3) the replacement of two electric heaters with gas/gas heat exchangers, and (4) the replacement two heat exchangers of the reference electrolyzer unit with one heat exchanger that uses steam from the biomass power plant. In all cases, 60% of the electricity required in the electrolyzer is covered by the biomass plant and 40% by the photovoltaic panels. When comparing the hybrid plants with the reference biomass power plant that has identical operation and structure as that incorporated in the hybrid plants, we observe an efficiency decrease that varies depending on the scenario. The efficiency decrease stems mainly from the low effectiveness of the photovoltaic panels (14.4%). When comparing the hybrid scenarios, we see that the elimination of the sweep gas decreases the power consumption due to the elimination of the compressor used to cover the pressure losses of the filter, the heat exchangers and the electrolyzer. Nevertheless, if the sweep gas is used to preheat the air entering the boiler of the biomass power plant, the efficiency of the plant increases. When replacing the electric heaters with gas-gas heat exchangers, the

  17. Down-conversion photoluminescence sensitizing plasmonic silver nanoparticles on ZnO nanorods to generate hydrogen by water splitting photochemistry

    Science.gov (United States)

    Kung, Po-Yen; Huang, Li-Wen; Shen, Tin-Wei; Wang, Wen-Lin; Su, Yen-Hsun; Lin, Melody I.

    2015-01-01

    Silver nanoparticles fabricated onto the surface of the ZnO nanorods form the photoanode and generate photoelectric current due to surface plasmon resonance, which serves as anode electrodes in photoelectrochemical hydrogen production. In order to increase the absorption spectrum of photoanode, organic pigments were utilized as photo-sensitizers to generate down-conversion photoluminescence to excite surface plasmon resonances of silver nanoparticles. The way of using light to carry the energy in electronic scattering regime runs the system for the enhancement of solar water splitting efficiency. It was significantly tuned in environmentally sustainable applications for power generation and development of alternative energy.

  18. Down-conversion photoluminescence sensitizing plasmonic silver nanoparticles on ZnO nanorods to generate hydrogen by water splitting photochemistry

    International Nuclear Information System (INIS)

    Silver nanoparticles fabricated onto the surface of the ZnO nanorods form the photoanode and generate photoelectric current due to surface plasmon resonance, which serves as anode electrodes in photoelectrochemical hydrogen production. In order to increase the absorption spectrum of photoanode, organic pigments were utilized as photo-sensitizers to generate down-conversion photoluminescence to excite surface plasmon resonances of silver nanoparticles. The way of using light to carry the energy in electronic scattering regime runs the system for the enhancement of solar water splitting efficiency. It was significantly tuned in environmentally sustainable applications for power generation and development of alternative energy

  19. Down-conversion photoluminescence sensitizing plasmonic silver nanoparticles on ZnO nanorods to generate hydrogen by water splitting photochemistry

    Energy Technology Data Exchange (ETDEWEB)

    Kung, Po-Yen; Huang, Li-Wen; Shen, Tin-Wei; Wang, Wen-Lin; Su, Yen-Hsun [Department of Materials Science and Engineering, National Cheng Kung University, Tainan, Taiwan (China); Lin, Melody I. [Department of Physics, University of California, Berkeley, California, 94720 (United States)

    2015-01-12

    Silver nanoparticles fabricated onto the surface of the ZnO nanorods form the photoanode and generate photoelectric current due to surface plasmon resonance, which serves as anode electrodes in photoelectrochemical hydrogen production. In order to increase the absorption spectrum of photoanode, organic pigments were utilized as photo-sensitizers to generate down-conversion photoluminescence to excite surface plasmon resonances of silver nanoparticles. The way of using light to carry the energy in electronic scattering regime runs the system for the enhancement of solar water splitting efficiency. It was significantly tuned in environmentally sustainable applications for power generation and development of alternative energy.

  20. Hydrogen generation using a calcium-bromine thermochemical water-splitting cycle

    International Nuclear Information System (INIS)

    The Secure Transportable Autonomous (STAR-H2) project is part of the US Department of Energy's (DOE's) Nuclear Energy Research Initiative (NERI) to develop Generation IV (Gen IV) nuclear reactors that will supply high-temperature (over 1100 K; 800 deg C) heat. The goal of NERI is to develop an economical, proliferation-resistant, sustainable, nuclear-based energy supply system based on a modular-sized fast reactor that is passively safe and cooled with heavy liquid metal. STAR-H2 consists of the following: - A 400-MWThermal reactor with Pb as the primary coolant; - Exchange of primary Pb coolant for a salt heat transfer pipe; - Exchange of salt for steam; - A combined thermochemical water-splitting cycle to generate hydrogen; - CO2 Brayton cycle to generate electricity (η = 47%), and - An optional capability to produce potable water from brackish or salt water. Here we review the thermodynamic basis for a three-stage calcium-bromine (Ca-Br) water-splitting cycle. The research builds upon pioneering work on the four-stage University of Tokyo Cycle no.3 (UT--3) process, but employs a plasma-chemical stage for the recovery of HBr as H2 and Br2 as a substitute for the final two stages of UT-3. A detailed process design, developed by using the ASPEN model, suggests that the practical efficiency is 39-45% for the STAR-H2 Ca-Br cycle. For each tonne of H2 produced hourly (1 000 kg/h), the demand for electricity for the plasma-chemical stage (13.5 MWe) is much lower than the demand (28.5 MWe) for a steam-electrolysis system. At current power grid heat-to-electricity efficiencies (η = 33%), there is a clear benefit for using the STAR-H2 Ca-Br cycle. Anticipating Brayton cycle performance (η = 47%), H2 production will demand a total power of 74 MWThermal per ton of H2 from the Gen IV reactor. It is important to recognize that there are capital and operating cost tradeoffs that will depend on the market value of low-carbon electricity in the future. Steam-electrolysis is a

  1. Model biogas steam reforming in a thin Pd-supported membrane reactor to generate clean hydrogen for fuel cells

    Science.gov (United States)

    Iulianelli, A.; Liguori, S.; Huang, Y.; Basile, A.

    2015-01-01

    Steam reforming of a model biogas mixture is studied for generating clean hydrogen by using an inorganic membrane reactor, in which a composite Pd/Al2O3 membrane separates part of the produced hydrogen through its selective permeation. The characteristics of H2 perm-selectivity of the fresh membrane is expressed in terms of H2/N2 ideal selectivity, in this case equal to 4300. Concerning biogas steam reforming reaction, at 380 °C, 2.0 bar H2O:CH4 = 3:1, GHSV = 9000 h-1 the permeate purity of the recovered hydrogen is around 96%, although the conversion (15%) and hydrogen recovery (>20%) are relatively low; on the contrary, at 450 °C, 3.5 bar H2O:CH4 = 4:1, GHSV = 11000 h-1 the conversion is increased up to more than 30% and the recovery of hydrogen to about 70%. This novel work constitutes a reference study for new developments on biogas steam reforming reaction in membrane reactors.

  2. The generation of hydrogen peroxide by the UVA irradiation of human lens proteins

    International Nuclear Information System (INIS)

    The water-insoluble proteins from aged human lens are known to contain protein-bound chromophores that act as UVA sensitizers. The irradiation of a sonication-solubilized, water-insoluble fraction from human lenses (55-75 years) with UVA light (1.5 kJ/cm2, λ > 338nm) caused an oxygen-dependent photolysis of tryptophan, not seen when either α-crystallin or lysozyme were irradiated. The suggested requirement for active oxygen species was consistent with a linear increase in hydrogen peroxide formation, which was also observed. A final concentration of 55 μM H2 O2 was attained, with no H2 O2 being detected in either dark-incubated controls or in irradiated samples of native proteins. The UVA-dependent H2 O2 formation was increased 50% by superoxide dismutase (SOD) and abolished by catalase, arguing for the initial generation of superoxide anion. A linear photolysis of histidine and tryptophan was also seen; however, the addition of SOD or SOD and catalase had no effect on the photolytic destruction of either amino acid. Superoxide dismutase increased the oxidation of protein SH groups implicating H2 O2, but SOD and catalase caused a decrease in SH oxidation only at later time periods. The direct addition of H2 O2 to a water-insoluble sonicate supernatant fraction caused only a slight oxidation of SH groups, but this was increased four- to eight-fold when the protein was denatured in 4.0 M guanidine hydrochloride. (author)

  3. Optimization of efficiency and energy density of passive micro fuel cells and galvanic hydrogen generators

    CERN Document Server

    Hahn, Robert; Krumbholz, Steffen; Reichl, Herbert

    2008-01-01

    A PEM micro fuel cell system is described which is based on self-breathing PEM micro fuel cells in the power range between 1 mW and 1W. Hydrogen is supplied with on-demand hydrogen production with help of a galvanic cell, that produces hydrogen when Zn reacts with water. The system can be used as a battery replacement for low power applications and has the potential to improve the run time of autonomous systems. The efficiency has been investigated as function of fuel cell construction and tested for several load profiles.

  4. Optimization of efficiency and energy density of passive micro fuel cells and galvanic hydrogen generators

    OpenAIRE

    Hahn, Robert; Wagner, Stefan; Krumbholz, Steffen; Reichl, Herbert

    2008-01-01

    A PEM micro fuel cell system is described which is based on self-breathing PEM micro fuel cells in the power range between 1 mW and 1W. Hydrogen is supplied with on-demand hydrogen production with help of a galvanic cell, that produces hydrogen when Zn reacts with water. The system can be used as a battery replacement for low power applications and has the potential to improve the run time of autonomous systems. The efficiency has been investigated as function of fuel cell construction and te...

  5. Colloidal CdS nanorods decorated with subnanometer sized Pt clusters for photocatalytic hydrogen generation

    International Nuclear Information System (INIS)

    Colloidal CdS nanorods have been decorated with extremely small, subnanometer sized Pt clusters and used for photocatalytic hydrogen production. We also show highly selective decoration of CdS nanorods with uniform, relatively large (4.8 nm mean size) Pt nanoparticles, with a remarkably high (90%) yield of samples decorated with exactly one Pt particle per rod. Samples with large Pt particles show no increase in hydrogen evolution rate compared to small Pt clusters, which implies that efficient hydrogen production utilizing CdS nanorods with reduced amounts of Pt is possible.

  6. PtRu-LiCoO 2—an efficient catalyst for hydrogen generation from sodium borohydride solutions

    Science.gov (United States)

    Krishnan, Palanichamy; Yang, Tae-Hyun; Lee, Won-Yong; Kim, Chang-Soo

    Hydrogen generation by the hydrolysis of aqueous sodium borohydride (NaBH 4) solutions is studied using IRA-400 anion resin dispersed Pt, Ru catalysts and lithium cobalt oxide (LiCoO 2) supported Pt, Ru and PtRu catalysts. The performance of the LiCoO 2 supported catalysts is better than that of ion-exchange resin dispersed catalysts. There is a marked concentration dependence on the performance of the LiCoO 2 supported catalysts and the hydrogen generation rate decreases if the borohydride concentration is increased beyond 10 wt.%. The efficiency of PtRu-LiCoO 2 is almost double that of either Ru-LiCoO 2 or Pt-LiCoO 2 for NaBH 4 concentrations up to 10 wt.%.

  7. Relations between oxygen and hydrogen generated by radiolysis in the systems of a CANDU 600

    International Nuclear Information System (INIS)

    The water that constitutes the coolant of the primary heat transport system, the moderator and the liquid control zones, decomposed under radiation producing as stable products oxygen, hydrogen and hydrogen peroxide throughout a complex mechanisms of radiolysis that involves ions and free radicals. These compound formed in different proportions alters the chemical control established for each system which purpose is to minimize the corrosion of the structural materials. In the present paper have been presented results of the modelling of the mentioned processes and it has been found that in the absence of a vapor phase, a relatively low concentration of hydrogen added to the water would be sufficient to control the formation of oxygen and hydrogen peroxide. The last species however, would remain in relatively high values inside a coolant fuel channel in the reactor core. (author)

  8. Hydrogen generation having CO2 removal with steam reforming

    Energy Technology Data Exchange (ETDEWEB)

    Kandaswamy, Duraiswamy; Chellappa, Anand S.; Knobbe, Mack

    2015-07-28

    A method for producing hydrogen using fuel cell off gases, the method feeding hydrocarbon fuel to a sulfur adsorbent to produce a desulfurized fuel and a spent sulfur adsorbent; feeding said desulfurized fuel and water to an adsorption enhanced reformer that comprises of a plurality of reforming chambers or compartments; reforming said desulfurized fuel in the presence of a one or more of a reforming catalyst and one or more of a CO2 adsorbent to produce hydrogen and a spent CO2 adsorbent; feeding said hydrogen to the anode side of the fuel cell; regenerating said spent CO2 adsorbents using the fuel cell cathode off-gases, producing a flow of hydrogen by cycling between said plurality of reforming chambers or compartments in a predetermined timing sequence; and, replacing the spent sulfur adsorbent with a fresh sulfur adsorbent at a predetermined time.

  9. Aqueous synthesis of CdS and CdSe/CdS tetrapods for photocatalytic hydrogen generation

    OpenAIRE

    A. Vaneski; Schneider, J; Susha, A. S.; Rogach, A. L.

    2014-01-01

    Straightforward, easily upscalable synthesis of monodisperse CdS and CdSe/CdS nanocrystals at room temperature in water/ethylendiamine mixtures is demonstrated, resulting in the formation of high-quality tetrapod-shaped nanoparticles in aqueous environment. It offers advantages for the subsequent direct use of aqueous-based colloidal nanocrystals for photocatalytic hydrogen generation from water, as it avoids any additional phase transfer necessary for any commonly employed nanoparticles synt...

  10. High Efficiency Generation of Hydrogen Fuels Using Nuclear Power - for the period August 1, 1999 through October 31, 1999

    Energy Technology Data Exchange (ETDEWEB)

    L. C. Brown

    2000-01-01

    OAK B188 High Efficiency Generation of Hydrogen Fuels Using Nuclear Power - for the period August 1, 1999 through October 31, 1999. The highlights for this period are: (1) The methodologies for searching the literature for potentially attractive thermochemical water-splitting cycles, storing cycle and reference data, and screening the cycles have been established; and (2) The water-splitting cycle screening criteria were established on schedule.

  11. Helium-Hydrogen generation arising from the 55Fe(n,x) reaction and its impact on fusion reactor

    International Nuclear Information System (INIS)

    In order to design the fusion reactor components neutron induced reaction (n,p) and (n,α) on the generated 55Fe to be studied. Detail study of 55Fe(n,p) reaction cross-section has been performed earlier. The present study describes the hydrogen and helium production from 55Fe(n,p) and 55Fe(n,α) reactions and its impact on fusion reactor

  12. All-Vanadium Dual Circuit Redox Flow Battery for Renewable Hydrogen Generation and Desulfurisation

    OpenAIRE

    Peljo, Pekka Eero; Vrubel, Heron; Amstutz, Veronique; Pandard, Justine; Morgado, Joana; Santasalo-Aarnio, Annukka; Lloyd, David; Gumy, Frederic; Dennison, C R; Toghill, Kathryn; Girault, Hubert

    2016-01-01

    An all-vanadium dual circuit redox flow battery is an electrochemical energy storage system capable to function as a conventional battery, but also to produce hydrogen and perform desulfurization when surplus of electricity is available by chemical discharge of the battery electrolytes. The hydrogen reactor chemically discharging the negative electrolyte has been designed and scaled up to kW scale, while different options to discharge the positive electrolyte have been evaluated, including ox...

  13. Production of hydrogen by electron transfer catalysis using conventional and photochemical means

    Science.gov (United States)

    Rillema, D. P.

    1981-01-01

    Alternate methods of generating hydrogen from the sulfuric acid thermal or electrochemical cycles are presented. A number of processes requiring chemical, electrochemical or photochemical methods are also presented. These include the design of potential photoelectrodes and photocatalytic membranes using Ru impregnated nafion tubing, and the design of experiments to study the catalyzed electrolytic formation of hydrogen and sulfuric acid from sulfur dioxide and water using quinones as catalysts. Experiments are carried out to determine the value of these approaches to energy conversion.

  14. The Development of Fuel Cell Technology for Electric Power Generation - From Spacecraft Applications to the Hydrogen Economy

    Science.gov (United States)

    Scott, John H.

    2005-01-01

    The fuel cell uses a catalyzed reaction between a fuel and an oxidizer to directly produce electricity. Its high theoretical efficiency and low temperature operation made it a subject of much study upon its invention ca. 1900, but its relatively high life cycle costs kept it as "solution in search of a problem" for its first half century. The first problem for which fuel cells presented a cost effective solution was, starting in the 1960's that of a power source for NASA's manned spacecraft. NASA thus invested, and continues to invest, in the development of fuel cell power plants for this application. However, starting in the mid-1990's, prospective environmental regulations have driven increased governmental and industrial interest in "green power" and the "Hydrogen Economy." This has in turn stimulated greatly increased investment in fuel cell development for a variety of terrestrial applications. This investment is bringing about notable advances in fuel cell technology, but these advances are often in directions quite different from those needed for NASA spacecraft applications. This environment thus presents both opportunities and challenges for NASA's manned space program.

  15. FINAL TECHNICAL REPORT for grant DE-FG02-93ER14353 "Carbon-Hydrogen Bond Functionalization Catalyzed by Transition Metal Systems"

    Energy Technology Data Exchange (ETDEWEB)

    Goldman, Alan S

    2012-05-21

    Alkanes are our most abundant organic resource but are highly resistant to selective chemical transformations. Alkenes (olefins) by contrast are the single most versatile class of molecules for selective transformations, and are intermediates in virtually every petrochemical process as well as a vast range of commodity and fine chemical processes. Over the course of this project we have developed the most efficient catalysts to date for the selective conversion of alkanes to give olefins, and have applied these catalysts to other dehydrogenation reactions. We have also developed some of the first efficient catalysts for carbonylation of alkanes and arenes to give aldehydes. The development of these catalysts has been accompanied by elucidation of the mechanism of their operation and the factors controlling the kinetics and thermodynamics of C-H bond activation and other individual steps of the catalytic cycles. This fundamental understanding will allow the further improvement of these catalysts, as well as the development of the next generation of catalysts for the functionalization of alkanes and other molecules containing C-H bonds.

  16. Modification of TiO2 nanotubes arrays by CdS and their photoelectrocatalytic hydrogen generation properties

    Institute of Scientific and Technical Information of China (English)

    ZHANG JianLing; ZHANG XingWang; LEI LeCheng

    2008-01-01

    In order to realize hydrogen generation under visible light, novel CdS/TiO2 nanotubes arrays are de-veloped by electrochemical anodization of Ti in 0.15 mol/L NH4F+ 0.08 mol/l. H2C2O4 electrolyte. The diameter of the nanotube is 80-100 nm and the length is approximately 550 nm. The CdS nano-particles are deposited on the TiO2 nanotubes arrays by chemical bath deposition (CBD) in the ammonia-thiourea system. A 300 W Xe lamp is used as the light source, CdS/TiO2 nanotube arrays are used as the photoanode with the application of 1.0 V bath voltage, and 0.1 mol/L Na2S + 0.04 mol/L Na2SO3 solution is used as the electrolyte, then the rate of photoelectrocatalytic hydrogen generation is 245.4 μl/(h·cm2). This opens new perspectives for photoelectrocatalytic hydrogen generation by using CdS/TiO2 nanotubes arrays.

  17. Steam reforming of ethanol over Ni/support catalysts for generation of hydrogen for fuel cell applications

    Energy Technology Data Exchange (ETDEWEB)

    Denis, Andrzej; Grzegorczyk, Wieslaw; Gac, Wojciech; Machocki, Andrzej [University of Maria Curie-Sklodowska, Faculty of Chemistry, Department of Chemical Technology, 3 Maria Curie-Sklodowska Square, 20-031 Lublin (Poland)

    2008-09-30

    The paper reports experimental results concerning the influence of the support nature (TiO{sub 2}, ZnO, Al{sub 2}O{sub 3} and Al{sub 2}O{sub 3}-Fe{sub 2}O{sub 3}) of nickel catalysts on their activity, selectivity and coking phenomenon in the steam reforming of ethanol in the range of 570-870K. The chemical transformations of ethanol occurring on the catalyst support make its chemical nature an important factor affecting the productivity and selectivity of the process. It was found that the most suitable supports in nickel catalysts designed for hydrogen generation in the steam reforming of ethanol are ZnO and TiO{sub 2}. Taking into consideration both the efficiency of hydrogen generation and the intensity of carbon deposition, the optimum temperature of the process of the steam reforming of ethanol is below 750K. An improvement in the selectivity of hydrogen generation and diminishing of the formation of undesirable products may be obtained by promoting nickel catalysts with sodium. (author)

  18. PVP-stabilized Ru–Rh nanoparticles as highly efficient catalysts for hydrogen generation from hydrolysis of ammonia borane

    International Nuclear Information System (INIS)

    Herein, the utilization of poly(N-vinyl-2-pyrrolidone)-protected ruthenium–rhodium nanoparticles (3.4 ± 1.4 nm) as highly efficient catalysts in the hydrolysis of ammonia borane for hydrogen generation is reported. They are prepared by co-reduction of ruthenium and rhodium metal ions in ethanol/water mixture by an alcohol reduction method and characterized by transmission electron microscopy-energy dispersive X-ray spectroscopy, ultraviolet–visible spectroscopy, and X-ray photoelectron spectroscopy. They are durable and highly efficient catalysts for hydrogen generation from the hydrolysis of ammonia borane even at very low concentrations and temperature, providing average turnover frequency of 386 mol H2 (mol cat)−1 min−1 and maximum hydrogen generation rate of 10,680 L H2 min−1 (mol cat)−1. Poly(N-vinyl-2-pyrrolidone)-protected ruthenium–rhodium nanoparticles also provide activation energy of 47.4 ± 2.1 kJ/mol for the hydrolysis of ammonia borane. - Highlights: • Ru-Rh@PVP NPs provide a TOF of 386 mol H2 (mol cat)−1 min−1 for hydrolysis of AB. • Maximum HG rate is 9680 L H2 min−1 (mol cat)−1 for the hydrolysis of AB. • Activation energy is 47.4 ± 2.1 kJ mol−1 for the hydrolysis of AB

  19. Detailed design data package: 1.9a Measure Hydrogen Generation during formating; 1.10a Nitrate Salt Reaction

    Energy Technology Data Exchange (ETDEWEB)

    Wiemers, K.D.; Langowski, M.H.; Powell, M.R.

    1996-03-01

    This data package provides test data on gas generation rates during formating of NCAW (neutralized current acid waste) and on nitrate salt reactions in dried SRAT/SME NCAW feeds. These issues correspond to the HWVP architectural engineer firm, Fluor Daniels, technology data needs, item 1.9a (Hydrogen Generation) and item 1.10a (Nitrate Salt reactions). This work was performed in accordance with the Fiscal Year 1991 Statement of Work for Applied Technology Tasks to be Performed by Pacific Northwest Laboratory in Support of the Hanford Waste Vitrification Plant Project (Kruger 1991).

  20. A third-generation dispersion and third-generation hydrogen bonding corrected PM6 method: PM6-D3H+

    Directory of Open Access Journals (Sweden)

    Jimmy C. Kromann

    2014-06-01

    Full Text Available We present new dispersion and hydrogen bond corrections to the PM6 method, PM6-D3H+, and its implementation in the GAMESS program. The method combines the DFT-D3 dispersion correction by Grimme et al. with a modified version of the H+ hydrogen bond correction by Korth. Overall, the interaction energy of PM6-D3H+ is very similar to PM6-DH2 and PM6-DH+, with RMSD and MAD values within 0.02 kcal/mol of one another. The main difference is that the geometry optimizations of 88 complexes result in 82, 6, 0, and 0 geometries with 0, 1, 2, and 3 or more imaginary frequencies using PM6-D3H+ implemented in GAMESS, while the corresponding numbers for PM6-DH+ implemented in MOPAC are 54, 17, 15, and 2. The PM6-D3H+ method as implemented in GAMESS offers an attractive alternative to PM6-DH+ in MOPAC in cases where the LBFGS optimizer must be used and a vibrational analysis is needed, e.g., when computing vibrational free energies. While the GAMESS implementation is up to 10 times slower for geometry optimizations of proteins in bulk solvent, compared to MOPAC, it is sufficiently fast to make geometry optimizations of small proteins practically feasible.

  1. Nano-design of quantum dot-based photocatalysts for hydrogen generation using advanced surface molecular chemistry

    KAUST Repository

    Yu, Weili

    2015-01-01

    Efficient photocatalytic hydrogen generation in a suspension system requires a sophisticated nano-device that combines a photon absorber with effective redox catalysts. This study demonstrates an innovative molecular linking strategy for fabricating photocatalytic materials that allow effective charge separation of excited carriers, followed by efficient hydrogen evolution. The method for the sequential replacement of ligands with appropriate molecules developed in this study tethers both quantum dots (QDs), as photosensitizers, and metal nanoparticles, as hydrogen evolution catalysts, to TiO2 surfaces in a controlled manner at the nano-level. Combining hydrophobic and hydrophilic interactions on the surface, CdSe-ZnS core-shell QDs and an Au-Pt alloy were attached to TiO2 without overlapping during the synthesis. The resultant nano-photocatalysts achieved substantially high-performance visible-light-driven photocatalysis for hydrogen evolution. All syntheses were conducted at room temperature and in ambient air, providing a promising route for fabricating visible-light-responsive photocatalysts.

  2. Highly Extensible Supramolecular Elastomers with Large Stress Generation Capability Originating from Multiple Hydrogen Bonds on the Long Soft Network Strands.

    Science.gov (United States)

    Hayashi, Mikihiro; Noro, Atsushi; Matsushita, Yushu

    2016-04-01

    Highly extensible supramolecular elastomers are prepared from ABA triblock-type copolymers bearing glassy end blocks and a long soft middle block with multiple hydrogen bonds. The copolymer used is polystyrene-b-[poly(butyl acrylate)-co-polyacrylamide]-b-polystyrene (S-Ba-S), which is synthesized via reversible addition-fragmentation chain transfer (RAFT) polymerization. Tensile tests reveal that the breaking elongation (εb ) increases with an increase in the middle block molecular weight (Mmiddle ). Especially, the largest S-Ba-S with Mmiddle of 3140k, which is synthesized via high-pressure RAFT polymerization, achieves εb of over 2000% with a maximum tensile stress of 3.6 MPa, while the control sample without any middle block hydrogen bonds, polystyrene-b-poly(butyl acrylate)-b-polystyrene with Mmiddle of 2780k, is merely a viscous material due to the large volume fraction of soft block. Thus, incorporation of hydrogen bonds into the large molecular weight soft middle block is found to be beneficial to prepare supramolecular elastomers attaining high extensibility and sufficiently large stress generation ability simultaneously. This outcome is probably due to concerted combination of entropic changes and internal potential energy changes originating from the dissociation of multiple hydrogen bonds by elongation. PMID:26914643

  3. Methane Formation by Flame-Generated Hydrogen Atoms in the Flame Ionization Detector

    DEFF Research Database (Denmark)

    Holm, Torkil; Madsen, Jørgen Øgaard

    1996-01-01

    The precombustion degradation of organic compounds in the flame ionization detector has been studied (1) by heating the additives in hydrogen in a quartz capillary and analyzing the reaction products by GC and (2) by following the degradation of the additives in a hydrogen flame, by means of a thin...... fused silica probe inserted from the bottom of the flame and connected to the ion source of a mass spectrometer. The results show that the thermic hydrogenolysis of hydrocarbons at flame temperatures produces mixtures of methane, ethene, and ethyne. In the flame, however, ethyne, benzene, isobutane...... atoms, which are formed in the burning hydrogen and which diffuse into the inner core of the flame. The quantitative formation of methane appears to explain the "equal per carbon" rule for the detector response of hydrocarbons, since all carbons are "exchanged" for methane molecules....

  4. Pentlandite rocks as sustainable and stable efficient electrocatalysts for hydrogen generation

    Science.gov (United States)

    Konkena, Bharathi; Junge Puring, Kai; Sinev, Ilya; Piontek, Stefan; Khavryuchenko, Oleksiy; Dürholt, Johannes P.; Schmid, Rochus; Tüysüz, Harun; Muhler, Martin; Schuhmann, Wolfgang; Apfel, Ulf-Peter

    2016-07-01

    The need for sustainable catalysts for an efficient hydrogen evolution reaction is of significant interest for modern society. Inspired by comparable structural properties of [FeNi]-hydrogenase, here we present the natural ore pentlandite (Fe4.5Ni4.5S8) as a direct `rock' electrode material for hydrogen evolution under acidic conditions with an overpotential of 280 mV at 10 mA cm-2. Furthermore, it reaches a value as low as 190 mV after 96 h of electrolysis due to surface sulfur depletion, which may change the electronic structure of the catalytically active nickel-iron centres. The `rock' material shows an unexpected catalytic activity with comparable overpotential and Tafel slope to some well-developed metallic or nanostructured catalysts. Notably, the `rock' material offers high current densities (performance of pentlandites as `rock' electrode labels this ore as a promising electrocatalyst for future hydrogen-based economy.

  5. Advanced chemical hydride-based hydrogen generation/storage system for fuel cell vehicles

    Energy Technology Data Exchange (ETDEWEB)

    Breault, R.W.; Rolfe, J. [Thermo Power Corp., Waltham, MA (United States)

    1998-08-01

    Because of the inherent advantages of high efficiency, environmental acceptability, and high modularity, fuel cells are potentially attractive power supplies. Worldwide concerns over clean environments have revitalized research efforts on developing fuel cell vehicles (FCV). As a result of intensive research efforts, most of the subsystem technology for FCV`s are currently well established. These include: high power density PEM fuel cells, control systems, thermal management technology, and secondary power sources for hybrid operation. For mobile applications, however, supply of hydrogen or fuel for fuel cell operation poses a significant logistic problem. To supply high purity hydrogen for FCV operation, Thermo Power`s Advanced Technology Group is developing an advanced hydrogen storage technology. In this approach, a metal hydride/organic slurry is used as the hydrogen carrier and storage media. At the point of use, high purity hydrogen will be produced by reacting the metal hydride/organic slurry with water. In addition, Thermo Power has conceived the paths for recovery and regeneration of the spent hydride (practically metal hydroxide). The fluid-like nature of the spent hydride/organic slurry will provide a unique opportunity for pumping, transporting, and storing these materials. The final product of the program will be a user-friendly and relatively high energy storage density hydrogen supply system for fuel cell operation. In addition, the spent hydride can relatively easily be collected at the pumping station and regenerated utilizing renewable sources, such as biomass, natural, or coal, at the central processing plants. Therefore, the entire process will be economically favorable and environmentally friendly.

  6. Preliminary analysis of an hydrogen generator system based on nuclear energy in the Laguna Verde site

    International Nuclear Information System (INIS)

    The shortage of fossil fuels in the next future, as well as the growing one demand of energetics and the high cost of the production of alternating fuels, it forces us to take advantage of to the maximum the fossil fuel with the one which we count and to look for the form of producing alternating fuels at a low cost and better even if these supply sources are reliable and non pollutants. It is intended a solution to the shortage of fuel; to use the thermal energy liberated of some appropriate nuclear reactor to be able to obtain a fuel but clean and relatively cheap as it is the hydrogen. In the first place the methods were looked for to produce hydrogen using thermal energy, later it was analyzed the temperature liberated by the existent nuclear reactors as well as the advanced designs, according to this liberated temperature settled down that the methods but feasible to produce hydrogen its were the one of reformed with water stream of the natural gas (methane) and the other one of the S-I thermochemical cycle, and the nuclear reactors that give the thermal energy for this production they are those of gas of high temperature. Once established the processes and the appropriate reactors, it was analyzed the site of Laguna Verde, with relationship to the free space to be able to place the reactor and the plant producer of hydrogen, as well as the direction in which blow the dominant winds and the near towns to the place, it was carried out an analysis of some explosion of tanks that could store hydrogen and the damage that its could to cause depending from the distance to which its were of the fire. Finally it was carried out an evaluation of capital and of operation costs for those two methods of hydrogen production. (Author)

  7. CATALYTIC GENERATION OF HYDROGEN FROM BIOMASS DERIVED LACTIC ACID VIA AQUEOUS PHASE REFORMING

    OpenAIRE

    Bosilj, Monika

    2015-01-01

    Hydrogen production from aqueous phase reforming (APR) of organic acids in aqueous phase and from residue of a biomass decomposition process over 3 wt% Pt/ZrO2 has been studied in the absence and presence of barium ions. The results have been compared with Pt/TiO2, Pt/C and Ni/C catalysts. Having identified barium hydroxide as a promising reagent in combination with Pt/ZrO2 catalyst for the hydrogen production out of organic acids, the method for the lactic acid conversion was extended. Lacti...

  8. Reaction Mechanisms of Ethylene Hydrogenation Catalyzed by Gold(I) Complexes%金(I)配合物催化乙烯加氢的反应机理

    Institute of Scientific and Technical Information of China (English)

    仇毅翔; 万明达; 陈先阳; 王曙光

    2013-01-01

    The reaction mechanisms of ethylene hydrogenation catalyzed by Au(I) complexes AuX (X=F, Cl, Br, I) and AuPR3+ (R = F, Cl, Br, I, H, Me, Ph) were investigated using density functional theory at the B3LYP level. The calculated results indicated that Au(I) complexes were effective catalysts in the hydrogenation of ethylene. AuPR3+ showed higher catalytic activity than AuX and the effect of changing the electron donating or withdrawing ability of the ligand on catalytic activity was large. Natural bond orbital analysis indicated that the interactions between the Au(I) complex and H2/C2H4 not only weakened the H―H/C=C bond strength, but also decreased the energy of the σ*H ― H、π*C=C orbital level. As a result, the energy differences of πC=C-σ*H ― H/σH ― H-π*C=C decreased, and ethylene hydrogenation was facilitated. A linear correlation was observed between the activation energies and πC=C-σ*H ― H/σH ― H-π*C=C. The more an Au(I) complex affected the σ*H―H/π*C=C orbital levels, the higher its catalytic activity.%  采用密度泛函理论B3LYP方法,对两类金(I)配合物AuX (X=F, Cl, Br, I)和AuPR3+(R=F, Cl, Br, I, H, Me, Ph)催化C2H4加氢反应的机理进行了理论研究.计算显示Au(I)配合物对C2H4氢化具有较好的催化效果,其作用下的加氢反应存在“活化H―H键后再与C2H4反应”和“活化C=C键后再与H2反应”两种途径,前者的活化能较后者低90-120 kJ·mol-1,因而具有明显的能量优势.研究表明AuPR3+的催化能力明显强于AuX.此外, X/PR3基团供、吸电子能力的变化对配合物的催化能力也具有较为显著的影响.电子结构分析显示Au(I)配合物在C2H4加氢反应中不仅能够削弱 H―H、C=C 键的强度,还使 H2σ*H―H、C2H4π*C=C轨道能级下降,从而缩小了πC=C-σ*H―H或σH―H-π*C=C轨道间的能级差,促进了 C2H4-H2反应中的电子离域,从而降低禁阻反应发生的难度.σ*H―H、π*C=C轨道能级改变量与

  9. Muon catalyzed fusion under compressive conditions

    International Nuclear Information System (INIS)

    The viability of a symbiotic combination of Muon Catalyzed Fusion (μCF) and high density generation processes has been investigated. The muon catalyzed fusion reaction rates are formulated in the temperature and density range found under moderate compressive conditions. Simplified energy gain and power balance calculations indicate that significant energy gain occurs only if standard type deuterium-tritium (dt) fusion is ignited. A computer simulation of the hydrodynamics and fusion kinetics of a spherical deuterium-tritium pellet implosion including muons is performed. Using the muon catalyzed fusion reaction rates formulated and under ideal conditions, the pellet ignites (and thus has a significant energy gain) only if the initial muon concentration is approximately 1017 cm-3. The muons need to be delivered to the pellet within a very short-time (≅ 1 ns). The muon pulse required in order to make the high density and temperature muon catalyzed fusion scheme viable is beyond the present technology for muon production. (orig.)

  10. Hydrogen peroxide generation in caco-2 cell culture medium by addition of phenolic compounds: effect of ascorbic acid.

    Science.gov (United States)

    Roques, Sylvie Cambon; Landrault, Nicolas; Teissèdre, Pierre-Louis; Laurent, Caroline; Besançon, Pierre; Rouane, Jean-Max; Caporiccio, Bertrand

    2002-05-01

    Phenolic compounds have recently attracted special attention due to their beneficial health effects; their intestinal absorption and bioavailability need, therefore, to be investigated and Caco-2 cell culture model appeared as a promising tool. We have shown herein that the addition of a grape seed extract (GSE) to Dulbecco's modified Eagle's medium (DMEM) used for Caco-2 cell culture leads to a substantial loss of catechin, epicatechin and B2 and B3 dimers from GSE in the medium after 24 h and to a production of hydrogen peroxide (H2O2). When 1420 microM ascorbic acid is added to the DMEM, such H2O2 production was prevented. This hydrogen peroxide generation substantially involves inorganic salts from the DMEM. We recommend that ascorbic acid be added to circumvent such a risk. PMID:12150547

  11. Aqueous synthesis of CdS and CdSe/CdS tetrapods for photocatalytic hydrogen generation

    Directory of Open Access Journals (Sweden)

    A. Vaneski

    2014-01-01

    Full Text Available Straightforward, easily upscalable synthesis of monodisperse CdS and CdSe/CdS nanocrystals at room temperature in water/ethylendiamine mixtures is demonstrated, resulting in the formation of high-quality tetrapod-shaped nanoparticles in aqueous environment. It offers advantages for the subsequent direct use of aqueous-based colloidal nanocrystals for photocatalytic hydrogen generation from water, as it avoids any additional phase transfer necessary for any commonly employed nanoparticles synthesized in organic medium. Being decorated with platinum as a co-catalyst, CdSe/CdS tetrapods achieve hydrogen evolution rates of up to 25 mmol/g per hour, which favorably compares to previously reported studies on CdS nanorods.

  12. Pentlandite rocks as sustainable and stable efficient electrocatalysts for hydrogen generation.

    Science.gov (United States)

    Konkena, Bharathi; Junge Puring, Kai; Sinev, Ilya; Piontek, Stefan; Khavryuchenko, Oleksiy; Dürholt, Johannes P; Schmid, Rochus; Tüysüz, Harun; Muhler, Martin; Schuhmann, Wolfgang; Apfel, Ulf-Peter

    2016-01-01

    The need for sustainable catalysts for an efficient hydrogen evolution reaction is of significant interest for modern society. Inspired by comparable structural properties of [FeNi]-hydrogenase, here we present the natural ore pentlandite (Fe4.5Ni4.5S8) as a direct 'rock' electrode material for hydrogen evolution under acidic conditions with an overpotential of 280 mV at 10 mA cm(-2). Furthermore, it reaches a value as low as 190 mV after 96 h of electrolysis due to surface sulfur depletion, which may change the electronic structure of the catalytically active nickel-iron centres. The 'rock' material shows an unexpected catalytic activity with comparable overpotential and Tafel slope to some well-developed metallic or nanostructured catalysts. Notably, the 'rock' material offers high current densities (≤650 mA cm(-2)) without any loss in activity for approximately 170 h. The superior hydrogen evolution performance of pentlandites as 'rock' electrode labels this ore as a promising electrocatalyst for future hydrogen-based economy. PMID:27461840

  13. Water leak detection in sodium heated steam generators through measurement of hydrogen concentration in sodium

    International Nuclear Information System (INIS)

    This report includes a description of apparatus for measuring hydrogen concentration in the secondary sodium system of the PHENIX reactor. The calibration method and results obtained since the commissioning of the reactor are also described. Mention is made of improvements to be built into SUPER PHENIX

  14. Pentlandite rocks as sustainable and stable efficient electrocatalysts for hydrogen generation

    Science.gov (United States)

    Konkena, Bharathi; junge Puring, Kai; Sinev, Ilya; Piontek, Stefan; Khavryuchenko, Oleksiy; Dürholt, Johannes P.; Schmid, Rochus; Tüysüz, Harun; Muhler, Martin; Schuhmann, Wolfgang; Apfel, Ulf-Peter

    2016-01-01

    The need for sustainable catalysts for an efficient hydrogen evolution reaction is of significant interest for modern society. Inspired by comparable structural properties of [FeNi]-hydrogenase, here we present the natural ore pentlandite (Fe4.5Ni4.5S8) as a direct ‘rock' electrode material for hydrogen evolution under acidic conditions with an overpotential of 280 mV at 10 mA cm−2. Furthermore, it reaches a value as low as 190 mV after 96 h of electrolysis due to surface sulfur depletion, which may change the electronic structure of the catalytically active nickel–iron centres. The ‘rock' material shows an unexpected catalytic activity with comparable overpotential and Tafel slope to some well-developed metallic or nanostructured catalysts. Notably, the ‘rock' material offers high current densities (≤650 mA cm−2) without any loss in activity for approximately 170 h. The superior hydrogen evolution performance of pentlandites as ‘rock' electrode labels this ore as a promising electrocatalyst for future hydrogen-based economy. PMID:27461840

  15. Environmental meticillin-resistant Staphylococcus aureus (MRSA) disinfection using dry-mist-generated hydrogen peroxide

    DEFF Research Database (Denmark)

    Bartels, M.D.; Kristoffersen, K.; Slotsbjerg, T.;

    2008-01-01

    Meticillin-resistant Staphylococcus aureus (MRSA) is a major problem in hospitals worldwide. Hand hygiene is recognised as crucial in limiting the spread of MRSA but less is known about the role of MRSA reservoirs in the inanimate hospital environment. We evaluated the effect of hydrogen peroxide...

  16. Integration of first and second generation biofuels: Fermentative hydrogen production from wheat grain and straw

    NARCIS (Netherlands)

    Panagiotopoulos, I.A.; Bakker, R.R.C.; Vrije, de G.J.; Claassen, P.A.M.; Koukios, E.G.

    2013-01-01

    Integrating of lignocellulose-based and starch-rich biomass-based hydrogen production was investigated by mixing wheat straw hydrolysate with a wheat grain hydrolysate for improved fermentation. Enzymatic pretreatment and hydrolysis of wheat grains led to a hydrolysate with a sugar concentration of

  17. The transmission of wind power generated in the Argentine Patagonia, to the consumption centres, using the hydrogen energy vector

    Energy Technology Data Exchange (ETDEWEB)

    Spinadel, E.; Gracia Nunez, S.L.; Gamallo, F. [University of Buenos Aires, GENCo Group, Buenos Aires (Argentina)

    1996-12-31

    In this paper, an analysis is performed, concerning the feasibility of using the same wind farms, presented by E. Spinadel at ECWEC`93, (Why do I say ``Yes`` now) with the same installed power, exclusively for producing Hydrogen at the installation site. This Hydrogen would later be used as an energy vector, to reach the existing networks in the north of Rio Negro, where it would be burned in conventional power plants, to produce electricity with synchronous machines, feeding the power into the network there. In this approach, there exists no limitation, such as the 10% mentioned in Travemunde and any amount of energy that might be extracted from the wind can be applied to generating hydrogen through an improved electrolytic process. Notwithstanding the yield chain resulting from multiple energy conversions, the electric energy in this way obtainable from the same group of wind farms, is greater than that which might be obtained as from the primitive scheme. Under the considered working hypothesis, within the Hydrogen alternative, it is possible to generate and feed into the network 4,457 GWh more than under the original alternative submitted at Travemunde. This implies a 37% increase on the net wind power conversion, owing to the conversion to H{sub 2}. Let it be said that this is attainable in spite of the extended intermediate yield chain, thanks to the possibility of making in this way better use of the available wind power, being no longer subject to the former network stability conditions, in voltage and frequency. (Author)

  18. Novel Hydrogen Bioreactor and Detection Apparatus.

    Science.gov (United States)

    Rollin, Joseph A; Ye, Xinhao; Del Campo, Julia Martin; Adams, Michael W W; Zhang, Y-H Percival

    2016-01-01

    In vitro hydrogen generation represents a clear opportunity for novel bioreactor and system design. Hydrogen, already a globally important commodity chemical, has the potential to become the dominant transportation fuel of the future. Technologies such as in vitro synthetic pathway biotransformation (SyPaB)-the use of more than 10 purified enzymes to catalyze unnatural catabolic pathways-enable the storage of hydrogen in the form of carbohydrates. Biohydrogen production from local carbohydrate resources offers a solution to the most pressing challenges to vehicular and bioenergy uses: small-size distributed production, minimization of CO2 emissions, and potential low cost, driven by high yield and volumetric productivity. In this study, we introduce a novel bioreactor that provides the oxygen-free gas phase necessary for enzymatic hydrogen generation while regulating temperature and reactor volume. A variety of techniques are currently used for laboratory detection of biohydrogen, but the most information is provided by a continuous low-cost hydrogen sensor. Most such systems currently use electrolysis for calibration; here an alternative method, flow calibration, is introduced. This system is further demonstrated here with the conversion of glucose to hydrogen at a high rate, and the production of hydrogen from glucose 6-phosphate at a greatly increased reaction rate, 157 mmol/L/h at 60 °C. PMID:25022362

  19. Development of Al2O3 carrier-Ru composite catalyst for hydrogen generation from alkaline NaBH4 hydrolysis

    International Nuclear Information System (INIS)

    A recyclable and reusable Ru/Al2O3 catalyst is prepared for hydrogen generation from the hydrolysis process of alkaline sodium borohydride (NaBH4) solution. The hydrogen generation rate by the hydrolysis and methanolysis of alkaline NaBH4 was explored as a function of NaOH concentration. Meantime, the byproducts derived from the spent alkaline NaBH4 solution were characterized by X-ray diffraction (XRD), scanning electro microscope/energy dispersive spectrometer (SEM/EDS) and NMR (Nuclear Magnetic Resonance). The effect of NaOH concentration on the hydrogen generation from the hydrolysis of NaBH4 significantly depends on the type of catalysts. With increasing NaOH concentration, the hydrogen generation rates decrease when using ruthenium (Ru) composite as a catalyst. The hydrogen generation rate of the methanolysis of NaBH4 is significantly inhibited in the presence of NaOH as compared with the hydrolysis of NaBH4. The durability test of the Ru/Al2O3 catalyst shows that the hydrogen generation rate decreases with recycling and reuse. The XRD and NMR analysis results show that the borate hydrate (NaBO2 H2O) was derived from the hydrolysis of 20 wt% and 30 wt% NaBH4. -- Highlights: ► A recyclable Ru/Al2O3 catalyst was synthesized for hydrogen generation. ► Ru/Al2O3 significantly promotes the hydrogen generation rate from alkaline NaBH4 solution. ► The prepared Ru/Al2O3 catalyst can easily collect from the spent alkaline NaBH4 solution.

  20. Metal Nanoparticles Catalyzed Selective Carbon-Carbon Bond Activation in the Liquid Phase.

    Science.gov (United States)

    Ye, Rong; Yuan, Bing; Zhao, Jie; Ralston, Walter T; Wu, Chung-Yeh; Unel Barin, Ebru; Toste, F Dean; Somorjai, Gabor A

    2016-07-13

    Understanding the C-C bond activation mechanism is essential for developing the selective production of hydrocarbons in the petroleum industry and for selective polymer decomposition. In this work, ring-opening reactions of cyclopropane derivatives under hydrogen catalyzed by metal nanoparticles (NPs) in the liquid phase were studied. 40-atom rhodium (Rh) NPs, encapsulated by dendrimer molecules and supported in mesoporous silica, catalyzed the ring opening of cyclopropylbenzene at room temperature under hydrogen in benzene, and the turnover frequency (TOF) was higher than other metals or the Rh homogeneous catalyst counterparts. Comparison of reactants with various substitution groups showed that electron donation on the three-membered ring boosted the TOF of ring opening. The linear products formed with 100% selectivity for ring opening of all reactants catalyzed by the Rh NP. Surface Rh(0) acted as the active site in the NP. The capping agent played an important role in the ring-opening reaction kinetics. Larger particle size tended to show higher TOF and smaller reaction activation energy for Rh NPs encapsulated in either dendrimer or poly(vinylpyrrolidone). The generation/size of dendrimer and surface group also affected the reaction rate and activation energy. PMID:27322570

  1. Toward enhanced hydrogen generation from water using oxygen permeating LCF membranes

    KAUST Repository

    Wu, Xiao-Yu

    2015-01-01

    © the Owner Societies. Hydrogen production from water thermolysis can be enhanced by the use of perovskite-type mixed ionic and electronic conducting (MIEC) membranes, through which oxygen permeation is driven by a chemical potential gradient. In this work, water thermolysis experiments were performed using 0.9 mm thick La0.9Ca0.1FeO3-δ (LCF-91) perovskite membranes at 990 °C in a lab-scale button-cell reactor. We examined the effects of the operating conditions such as the gas species concentrations and flow rates on the feed and sweep sides on the water thermolysis rate and oxygen flux. A single step reaction mechanism is proposed for surface reactions, and three-resistance permeation models are derived. Results show that water thermolysis is facilitated by the LCF-91 membrane especially when a fuel is added to the sweep gas. Increasing the gas flow rate and water concentration on the feed side or the hydrogen concentration on the sweep side enhances the hydrogen production rate. In this work, hydrogen is used as the fuel by construction, so that a single-step surface reaction mechanism can be developed and water thermolysis rate parameters can be derived. Both surface reaction rate parameters for oxygen incorporation/dissociation and hydrogen-oxygen reactions are fitted at 990 °C. We compare the oxygen fluxes in water thermolysis and air separation experiments, and identify different limiting steps in the processes involving various oxygen sources and sweep gases for this 0.9 mm thick LCF-91 membrane. In the air feed-inert sweep case, the bulk diffusion and sweep side surface reaction are the two limiting steps. In the water feed-inert sweep case, surface reaction on the feed side dominates the oxygen permeation process. Yet in the water feed-fuel sweep case, surface reactions on both the feed and sweep sides are rate determining when hydrogen concentration in the sweep side is in the range of 1-5 vol%. Furthermore, long term studies show that the surface

  2. Performance analysis of an integrated biomass gasification and PEMFC (proton exchange membrane fuel cell) system: Hydrogen and power generation

    International Nuclear Information System (INIS)

    The PEMFC (proton exchange membrane fuel cell) is expected to play a significant role in next-generation energy systems. Because most hydrogen that is used as a fuel for PEMFCs is derived from the reforming of natural gas, the use of renewable energy sources such as biomass to produce this hydrogen offers a promising alternative. This study is focused on the performance analysis of an integrated biomass gasification and PEMFC system. The combined heat and power generation output of this integrated system is designed for residential applications, taking into account thermal and electrical demands. A flowsheet model of the integrated PEMFC system is developed and employed to analyze its performance with respect to various key operating parameters. A purification process consisting of a water–gas shift reactor and a preferential oxidation reactor is also necessary in order to reduce the concentration of CO in the synthesis gas to below 10 ppm for subsequent use in the PEMFC. The effect of load level on the performance of the PEMFC system is investigated. Based on an electrical load of 5 kW, it is found that the electrical efficiency of the PEMFC integrated system is 22%, and, when waste heat recovery is considered, the total efficiency of the PEMFC system is 51%. - Highlights: • Performance of a biomass gasification and PEMFC integrated system is analyzed. • A flowsheet model of the PEMFC integrated system is developed. • Effect of biomass sources and key parameters on hydrogen and power generation is presented. • The PEMFC integrated system is designed for small-scale power demand. • Effect of load changes on the performance of PEMFC is investigated

  3. PVP-stabilized Ru–Rh nanoparticles as highly efficient catalysts for hydrogen generation from hydrolysis of ammonia borane

    Energy Technology Data Exchange (ETDEWEB)

    Rakap, Murat, E-mail: mrtrakap@gmail.com

    2015-11-15

    Herein, the utilization of poly(N-vinyl-2-pyrrolidone)-protected ruthenium–rhodium nanoparticles (3.4 ± 1.4 nm) as highly efficient catalysts in the hydrolysis of ammonia borane for hydrogen generation is reported. They are prepared by co-reduction of ruthenium and rhodium metal ions in ethanol/water mixture by an alcohol reduction method and characterized by transmission electron microscopy-energy dispersive X-ray spectroscopy, ultraviolet–visible spectroscopy, and X-ray photoelectron spectroscopy. They are durable and highly efficient catalysts for hydrogen generation from the hydrolysis of ammonia borane even at very low concentrations and temperature, providing average turnover frequency of 386 mol H{sub 2} (mol cat){sup −1} min{sup −1} and maximum hydrogen generation rate of 10,680 L H{sub 2} min{sup −1} (mol cat){sup −1}. Poly(N-vinyl-2-pyrrolidone)-protected ruthenium–rhodium nanoparticles also provide activation energy of 47.4 ± 2.1 kJ/mol for the hydrolysis of ammonia borane. - Highlights: • Ru-Rh@PVP NPs provide a TOF of 386 mol H{sub 2} (mol cat){sup −1} min{sup −1} for hydrolysis of AB. • Maximum HG rate is 9680 L H{sub 2} min{sup −1} (mol cat){sup −1} for the hydrolysis of AB. • Activation energy is 47.4 ± 2.1 kJ mol{sup −1} for the hydrolysis of AB.

  4. Electrodeposited synthesis of self-supported Ni-P cathode for efficient electrocatalytic hydrogen generation

    Directory of Open Access Journals (Sweden)

    Ruixian Wu

    2016-06-01

    Full Text Available One of the key challenges for electrochemical water splitting is the development of low-cost and efficient hydrogen evolution cathode. In this work, a self-supported Ni-P cathode was synthesized by a facile electrodeposition method. The composition and morphology were characterized by X-ray diffraction, X-ray photoelectron spectroscopy, scanning electron microscopy and transmission electron microscopy. The Ni-P cathode performed low onset over-potential, good catalytic activity and long-term stability under neutral and alkaline conditions. The mechanism of Ni-P electrode for hydrogen production was discussed by electrochemical impedance spectroscopy. The excellent performance of Ni-P cathode was mainly attributed to the synergistic effect of phosphate anions and the self-supported feature.

  5. Complexes of earth-abundant metals for catalytic electrochemical hydrogen generation under aqueous conditions.

    Science.gov (United States)

    Thoi, V Sara; Sun, Yujie; Long, Jeffrey R; Chang, Christopher J

    2013-03-21

    Growing global energy demands and climate change motivate the development of new renewable energy technologies. In this context, water splitting using sustainable energy sources has emerged as an attractive process for carbon-neutral fuel cycles. A key scientific challenge to achieving this overall goal is the invention of new catalysts for the reductive and oxidative conversions of water to hydrogen and oxygen, respectively. This review article will highlight progress in molecular electrochemical approaches for catalytic reduction of protons to hydrogen, focusing on complexes of earth-abundant metals that can function in pure aqueous or mixed aqueous-organic media. The use of water as a reaction medium has dual benefits of maintaining high substrate concentration as well as minimizing the environmental impact from organic additives and by-products. PMID:23034627

  6. Raising efficiency of hydrogen generation from alkaline water electrolysis - Energy saving

    Energy Technology Data Exchange (ETDEWEB)

    Nikolic, Vladimir M.; Tasic, Gvozden S.; Maksic, Aleksandar D.; Saponjic, Djordje P.; Marceta Kaninski, Milica P. [Vinca Institute of Nuclear Sciences, Department of Physical Chemistry, 11001 Belgrade, POB 522 (RS); Miulovic, Snezana M. [University of Belgrade, Faculty of Physical Chemistry, 11001 Belgrade, POB 276 (RS)

    2010-11-15

    This paper presents an attempt to make the alkaline electrolytic production of hydrogen more efficient by adding in situ activating compounds in ionic and complex form. Cobalt and tungsten based ionic activators (i.a.), added directly into the electrolyte during the electrolytic process, reduce energy requirements per mass unit of hydrogen produced for about 15%, compared to non-activated system, for a number of current densities in a wide temperature range. Energy saving is higher at higher temperatures and on higher current densities. Structural and morphological characteristic of deposit formed on the cathode during the electrolytic process reveal very interesting and unique pattern with highly developed surface area and uniform distribution of the pores. Obtained deposit also exhibit a long term stability. (author)

  7. A tunable azine covalent organic framework platform for visible light-induced hydrogen generation

    Science.gov (United States)

    Vyas, Vijay S.; Haase, Frederik; Stegbauer, Linus; Savasci, Gökcen; Podjaski, Filip; Ochsenfeld, Christian; Lotsch, Bettina V.

    2015-09-01

    Hydrogen evolution from photocatalytic reduction of water holds promise as a sustainable source of carbon-free energy. Covalent organic frameworks (COFs) present an interesting new class of photoactive materials, which combine three key features relevant to the photocatalytic process, namely crystallinity, porosity and tunability. Here we synthesize a series of water- and photostable 2D azine-linked COFs from hydrazine and triphenylarene aldehydes with varying number of nitrogen atoms. The electronic and steric variations in the precursors are transferred to the resulting frameworks, thus leading to a progressively enhanced light-induced hydrogen evolution with increasing nitrogen content in the frameworks. Our results demonstrate that by the rational design of COFs on a molecular level, it is possible to precisely adjust their structural and optoelectronic properties, thus resulting in enhanced photocatalytic activities. This is expected to spur further interest in these photofunctional frameworks where rational supramolecular engineering may lead to new material applications.

  8. A polymer electrolyte fuel cell stack for stationary power generation from hydrogen fuel

    Energy Technology Data Exchange (ETDEWEB)

    Wilson, M.S.; Moeller-Holst, S.; Webb, D.M.; Zawodzinski, C.; Gottesfeld, S. [Los Alamos National Lab., NM (United States). Materials Science and Technology Div.

    1998-08-01

    The objective is to develop and demonstrate a 4 kW, hydrogen-fueled polymer electrolyte fuel cell (PEFC) stack, based on non-machined stainless steel hardware and on membrane/electrode assemblies (MEAs) of low catalyst loadings. The stack is designed to operate at ambient pressure on the air-side and can accommodate operation at higher fuel pressures, if so required. This is to be accomplished by working jointly with a fuel cell stack manufacturer, based on a CRADA. The performance goals are 57% energy conversion efficiency hydrogen-to-electricity (DC) at a power density of 0.9 kW/liter for a stack operating at ambient inlet pressures. The cost goal is $600/kW, based on present materials costs.

  9. Photocatalytic hydrogen generation with Ag-loaded LiNbO3

    Indian Academy of Sciences (India)

    Beata Zielińska

    2014-06-01

    In this contribiution LiNbO3 and Ag-loaded LiNbO3 photocatalysts were tested in the reaction of hydrogen evolution. The silver modified samples contained different loading of co-catalyst in the range of 0.5–4 wt%. It was essential to optimize the sample composition to achieve an efficient hydrogen evolution. The optimal sample contained 2 wt% of silver. The detailed analysis indicated that silver was deposited on the surface of LiNbO3 in the form of Ag2O. Therefore, it is supposed that Ag2O was responsible for the enhanced photocatalytic activity in the studied reaction. The crystallographic phases and optical and vibronic properties were examined by X-ray diffraction (XRD) and diffuse reflectance (DR) UV–Vis and resonance Raman spectroscopic methods, respectively. Morphology of the produced samples were studied using a highresolution transmission electron microscope (HRTEM).

  10. Theoretical Research Program on Bio-inspired Inorganic Hydrogen Generating Catalysts and Electrodes

    Energy Technology Data Exchange (ETDEWEB)

    Selloni, Annabella; Car, Roberto; Cohen, Morrel H.

    2014-04-17

    In this project, we have successfully designed and characterized a promising biomimetic catalyst/electrode complex, [FeFe]P/FeS2 for producing hydrogen from water. It is comprised of earth-abundant materials and, with a diffusion-limited rate in acidified water, is efficient as well as oxygen tolerant. The theoretical techniques we have developed and the experience we have gained are broadly applicable for the design and analysis of biomimetic electrochemically active catalysts.

  11. Generation of hydrogen peroxide in the developing rat heart: the role of elastin metabolism

    Czech Academy of Sciences Publication Activity Database

    Wilhelm, J.; Ošťádalová, Ivana; Vytášek, R.; Vajner, L.

    2011-01-01

    Roč. 358, 1-2 (2011), s. 215-220. ISSN 0300-8177 R&D Projects: GA MŠk(CZ) 1M0510 Grant ostatní: GA ČR(CZ) GAP303/11/0298 Institutional research plan: CEZ:AV0Z50110509 Keywords : rat heart * ontogenetic development * hydrogen peroxide * elastin * fluorescence Subject RIV: FA - Cardiovascular Diseases incl. Cardiotharic Surgery Impact factor: 2.057, year: 2011

  12. A tunable azine covalent organic framework platform for visible light-induced hydrogen generation

    OpenAIRE

    Vyas, Vijay S.; Haase, Frederik; Stegbauer, Linus; Savasci, Gökcen; Podjaski, Filip; Ochsenfeld, Christian; Lotsch, Bettina V.

    2015-01-01

    Hydrogen evolution from photocatalytic reduction of water holds promise as a sustainable source of carbon-free energy. Covalent organic frameworks (COFs) present an interesting new class of photoactive materials, which combine three key features relevant to the photocatalytic process, namely crystallinity, porosity and tunability. Here we synthesize a series of water- and photostable 2D azine-linked COFs from hydrazine and triphenylarene aldehydes with varying number of nitrogen atoms. The el...

  13. Process for Generation of Hydrogen Gas from Various Feedstocks Using Thermophilic Bacteria

    Energy Technology Data Exchange (ETDEWEB)

    Ooteghem Van, Suellen

    2005-09-13

    A method for producing hydrogen gas is provided comprising selecting a bacteria from the Order Thermotogales, subjecting the bacteria to a feedstock and to a suitable growth environment having an oxygen concentration below the oxygen concentration of water in equilibrium with air; and maintaining the environment at a predetermined pH and at a temperature of at least approximately 45 degrees C. for a time sufficient to allow the bacteria to metabolize the feedstock.

  14. Methane formation from CaCO3 reduction catalyzed by high pressure

    Institute of Scientific and Technical Information of China (English)

    Jin Yang Chen; Lu Jiang Jin; Jun Ping Dong; Hai Fei Zheng; Gui Yang Liu

    2008-01-01

    Under high pressures of several giga-pascals using hydrothermal diamond anvil cell,methane generated directly from CaCO3 reduction in gold-lined chamber is in situ measured by Raman spectroscopy at the temperature of 550 ℃.The reducing agents include FeO,SiO and natural fayalite (Fe2SiO4),and the resource of hydrogen are water and natural serpentine (Mg3Si2O5(OH)4).The study demonstrates the existence of abiogenic formation of methane under high pressures in the Earth's interior and that the application of high pressure to catalyze multicomponent reactions is a very promising method.

  15. Fractal disperse hydrogen sorption kinetics in spark discharge generated Mg/NbOx and Mg/Pd nanocomposites

    OpenAIRE

    Anastasopol, A.; Pfeiffer, T.V.; Schmidt-Ott, A.; Mulder, F.M.; Eijt, S.W.H.

    2011-01-01

    Isothermal hydrogen desorption of spark discharge generated Mg/NbOx and Mg/Pd metal hydride nanocomposites is consistently described by a kinetic model based on multiple reaction rates, in contrast to the Johnson-Mehl-Avrami-Kolmogorov [M. Avrami, J. Phys. Chem. 9, 177 (1941); W. A. Johnson and R. F. Mehl, Trans. Am. Inst. Min., Metal. Eng. 135, 416 (1939); A. N. Kolmogorov, Izv. Akad. Nauk SSSR, Ser. Mat. 3, 355 (1937); F. Liu, F. Sommer, C. Bos, and E. J. Mittemeijer, Int. Mat. Rev. 52, 193...

  16. Enhanced hydrogen generation using a saline catholyte in a two chamber microbial electrolysis cell

    KAUST Repository

    Nam, Joo-Youn

    2011-11-01

    High rates of hydrogen gas production were achieved in a two chamber microbial electrolysis cell (MEC) without a catholyte phosphate buffer by using a saline catholyte solution and a cathode constructed around a stainless steel mesh current collector. Using the non-buffered salt solution (68 mM NaCl) produced the highest current density of 131 ± 12 A/m3, hydrogen yield of 3.2 ± 0.3 mol H2/mol acetate, and gas production rate of 1.6 ± 0.2 m3 H2/m 3·d, compared to MECs with catholytes externally sparged with CO2 or containing a phosphate buffer. The salinity of the catholyte achieved a high solution conductivity, and therefore the electrode spacing did not appreciably affect performance. The coulombic efficiency with the cathode placed near the membrane separating the chambers was 83 ± 4%, similar to that obtained with the cathode placed more distant from the membrane (84 ± 4%). Using a carbon cloth cathode instead of the stainless steel mesh cathode did not significantly affect performance, with all reactor configurations producing similar performance in terms of total gas volume, COD removal, rcat and overall energy recovery. These results show MEC performance can be improved by using a saline catholyte without pH control. © 2011, Hydrogen Energy Publications, LLC. Published by Elsevier Ltd. All rights reserved.

  17. Interaction of gas phase atomic hydrogen with Pt(111):Direct evidence for the formation of bulk hydrogen species

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    Employing hot tungsten filament to thermal dissociate molecular hydrogen,we generated gas phase atomic hydrogen under ultra-high vacuum(UHV)conditions and investigated its interaction with Pt(111) surface.Thermal desorption spectroscopy(TDS)results demonstrate that adsorption of molecular hy- drogen on Pt(111)forms surface Had species whereas adsorption of atomic hydrogen forms not only surface Had species but also bulk Had species.Bulk Had species is more thermal-unstable than surface Had species on Pt(111),suggesting that bulk Had species is more energetic.This kind of weakly- adsorbed bulk Had species might be the active hydrogen species in the Pt-catalyzed hydrogenation reactions.

  18. Control of Hydrogen Photoproduction by the Proton Gradient Generated by Cyclic Electron Flow in Chlamydomonas reinhardtii[W

    Science.gov (United States)

    Tolleter, Dimitri; Ghysels, Bart; Alric, Jean; Petroutsos, Dimitris; Tolstygina, Irina; Krawietz, Danuta; Happe, Thomas; Auroy, Pascaline; Adriano, Jean-Marc; Beyly, Audrey; Cuiné, Stéphan; Plet, Julie; Reiter, Ilja M.; Genty, Bernard; Cournac, Laurent; Hippler, Michael; Peltier, Gilles

    2011-01-01

    Hydrogen photoproduction by eukaryotic microalgae results from a connection between the photosynthetic electron transport chain and a plastidial hydrogenase. Algal H2 production is a transitory phenomenon under most natural conditions, often viewed as a safety valve protecting the photosynthetic electron transport chain from overreduction. From the colony screening of an insertion mutant library of the unicellular green alga Chlamydomonas reinhardtii based on the analysis of dark-light chlorophyll fluorescence transients, we isolated a mutant impaired in cyclic electron flow around photosystem I (CEF) due to a defect in the Proton Gradient Regulation Like1 (PGRL1) protein. Under aerobiosis, nonphotochemical quenching of fluorescence (NPQ) is strongly decreased in pgrl1. Under anaerobiosis, H2 photoproduction is strongly enhanced in the pgrl1 mutant, both during short-term and long-term measurements (in conditions of sulfur deprivation). Based on the light dependence of NPQ and hydrogen production, as well as on the enhanced hydrogen production observed in the wild-type strain in the presence of the uncoupling agent carbonyl cyanide p-trifluoromethoxyphenylhydrazone, we conclude that the proton gradient generated by CEF provokes a strong inhibition of electron supply to the hydrogenase in the wild-type strain, which is released in the pgrl1 mutant. Regulation of the trans-thylakoidal proton gradient by monitoring pgrl1 expression opens new perspectives toward reprogramming the cellular metabolism of microalgae for enhanced H2 production. PMID:21764992

  19. Hydrogen and methane generation from large hydraulic plant: Thermo-economic multi-level time-dependent optimization

    International Nuclear Information System (INIS)

    Highlights: • We investigate H2 and CH4 production from very large hydraulic plant (14 GW). • We employ only “spilled energy”, not used by hydraulic plant, for H2 production. • We consider the integration with energy taken from the grid at different prices. • We consider hydrogen conversion in chemical reactors to produce methane. • We find plants optimal size using a time-dependent thermo-economic approach. - Abstract: This paper investigates hydrogen and methane generation from large hydraulic plant, using an original multilevel thermo-economic optimization approach developed by the authors. Hydrogen is produced by water electrolysis employing time-dependent hydraulic energy related to the water which is not normally used by the plant, known as “spilled water electricity”. Both the demand for spilled energy and the electrical grid load vary widely by time of year, therefore a time-dependent hour-by-hour one complete year analysis has been carried out, in order to define the optimal plant size. This time period analysis is necessary to take into account spilled energy and electrical load profiles variability during the year. The hydrogen generation plant is based on 1 MWe water electrolysers fuelled with the “spilled water electricity”, when available; in the remaining periods, in order to assure a regular H2 production, the energy is taken from the electrical grid, at higher cost. To perform the production plant size optimization, two hierarchical levels have been considered over a one year time period, in order to minimize capital and variable costs. After the optimization of the hydrogen production plant size, a further analysis is carried out, with a view to converting the produced H2 into methane in a chemical reactor, starting from H2 and CO2 which is obtained with CCS plants and/or carried by ships. For this plant, the optimal electrolysers and chemical reactors system size is defined. For both of the two solutions, thermo

  20. Mechanism of carbon monoxide reactions under high pressure catalyzed by acids and bases

    Energy Technology Data Exchange (ETDEWEB)

    Takezaki, Y.

    1978-05-01

    A review, based mainly on work done at Kyoto University, covers the mechanisms and kinetics of acid-catalyzed carbonylations, including the hydrogen fluoride-catalyzed addition of carbon monoxide to methallyl chloride, the sulfuric acid-catalyzed synthesis of succinic acid from acrylic acid, and the conversion of toluene to p-tolualdehyde in hydrogen fluoride/boron trifluoride by the Gattermann-Koch reaction; and of base-catalyzed reactions, including the production of methyl formate from methanol with 1,8-diazabicyclo (5,4,0)undec-7-ene catalyst and of malonic acid from potassium acetate and potassium carbonate. Graphs, tables, and 34 references.

  1. Production of HBR from bromine and steam for off-peak electrolytic hydrogen generation

    Energy Technology Data Exchange (ETDEWEB)

    Schlief, R.E.; Hanrahan, R.J.; Stoy, M.A. [Univ. of Florida, Gainesville, FL (United States)] [and others

    1995-09-01

    Progress is reported on the development of a renewable energy source based solar-electrolytic system for production of hydrogen and oxygen. It employs water, bromine, solar energy and supplemental electrical power. The concept is being developed by Solar Reactor Technologies, Inc., (SRT), with the U.S. Department of Energy (DOE). An overview of the nature and objectives of this program is provided here, and technical progress made during the first (three-month) performance period of the Phase I work effort is reported. The SRT concept entails (1) absorption of concentrated solar radiation by bromine vapor Br{sub 2(g)} in a high-temperature reactor producing Br{sub (g)} atoms, (2) reaction of Br{sub (g)} with water yielding hydrogen bromide (HBr), and (3) electrolysis of stored hydrogen bromide for production of H{sub 2(g)} and recovery of Br{sub 2(I)}. Incorporation of solar radiation in the primary photochemical step (1) reduces by 50 - 70% the electrical power required to split water. The SRT concept is very attractive from an economic viewpoint as well. The reversible fuel cell, employed in the SRT electrolysis concept is capitalized via its use in load leveling by the utility. A 1 kW solar reactor was designed and constructed during the first three-month performance period by SRT personnel at the University of Florida, Gainesville. It was employed in taking survey data of the reaction between bromine and steam at temperatures between 900 and 1300 K. This reaction was run under purely thermal conditions, i.e. in the absence of solar photons. The experimental data are reported and interpreted employing concomitant thermodynamic calculations. The anticipated improvement is discussed briefly as well as the effect of a photochemical boost to the reaction. The amount of this enhancement will be studied in the next three month performance period.

  2. Dye-sensitized Pt@TiO2 core–shell nanostructures for the efficient photocatalytic generation of hydrogen

    Directory of Open Access Journals (Sweden)

    Jun Fang

    2014-03-01

    Full Text Available Pt@TiO2 core–shell nanostructures were prepared through a hydrothermal method. The dye-sensitization of these Pt@TiO2 core–shell structures allows for a high photocatalytic activity for the generation of hydrogen from proton reduction under visible-light irradiation. When the dyes and TiO2 were co-excited through the combination of two irradiation beams with different wavelengths, a synergic effect was observed, which led to a greatly enhanced H2 generation yield. This is attributed to the rational spatial distribution of the three components (dye, TiO2, Pt, and the vectored transport of photogenerated electrons from the dye to the Pt particles via the TiO2 particle bridge.

  3. Room-Temperature and Aqueous-Phase Synthesis of Plasmonic Molybdenum Oxide Nanoparticles for Visible-Light-Enhanced Hydrogen Generation.

    Science.gov (United States)

    Shi, Jiayuan; Kuwahara, Yasutaka; Wen, Meicheng; Navlani-García, Miriam; Mori, Kohsuke; An, Taicheng; Yamashita, Hiromi

    2016-09-01

    A straightforward aqueous synthesis of MoO3-x nanoparticles at room temperature was developed by using (NH4 )6 Mo7 O24 ⋅4 H2 O and MoCl5 as precursors in the absence of reductants, inert gas, and organic solvents. SEM and TEM images indicate the as-prepared products are nanoparticles with diameters of 90-180 nm. The diffuse reflectance UV-visible-near-IR spectra of the samples indicate localized surface plasmon resonance (LSPR) properties generated by the introduction of oxygen vacancies. Owing to its strong plasmonic absorption in the visible-light and near-infrared region, such nanostructures exhibit an enhancement of activity toward visible-light catalytic hydrogen generation. MoO3-x nanoparticles synthesized with a molar ratio of Mo(VI) /Mo(V) 1:1 show the highest yield of H2 evolution. The cycling catalytic performance has been investigated to indicate the structural and chemical stability of the as-prepared plasmonic MoO3-x nanoparticles, which reveals its potential application in visible-light catalytic hydrogen production. PMID:27555123

  4. Generation of Useful Hydrocarbons and Hydrogen during Photocatalytic Decomposition of Acetic Acid on CuO/Rutile Photocatalysts

    Directory of Open Access Journals (Sweden)

    Sylwia Mozia

    2009-01-01

    Full Text Available The presented studies have focused on a photocatalytic generation of useful hydrocarbons, mainly methane and ethane, from acetic acid under N2 atmosphere. CuO-loaded rutile, as well as unmodified rutile and anatase-phase TiO2 photocatalysts were applied in the experiments. The efficiency of the catalysts towards methane generation changed in the following order: Cu-TiO2 (10% Cu > crude TiO2≈Cu-TiO2 (20% Cu > Cu-TiO2 (5% Cu > rutile. The amount of CH4 produced in the presence of the catalyst containing 10 wt% of Cu was higher for ca. 33% than in case of pure rutile. The concentration of ethane was 14–16 times lower than the amount of methane, regardless of the catalyst used. Low concentrations of hydrogen were also detected in the gaseous mixtures. After 5 hours of the process conducted with the catalyst containing 5–20 wt% of Cu the concentration of hydrogen amounted to 0.06–0.14 vol.%, respectively.

  5. Significant improvements in InGaN/GaN nano-photoelectrodes for hydrogen generation by structure and polarization optimization

    Science.gov (United States)

    Tao, Tao; Zhi, Ting; Liu, Bin; Li, Mingxue; Zhuang, Zhe; Dai, Jiangping; Li, Yi; Jiang, Fulong; Luo, Wenjun; Xie, Zili; Chen, Dunjun; Chen, Peng; Li, Zhaosheng; Zou, Zhigang; Zhang, Rong; Zheng, Youdou

    2016-02-01

    The photoelectrodes based on III-nitride semiconductors with high energy conversion efficiency especially for those self-driven ones are greatly desirable for hydrogen generation. In this study, highly ordered InGaN/GaN multiple-quantum-well nanorod-based photoelectrodes have been fabricated by a soft UV-curing nano-imprint lithography and a top-down etching technique, which improve the incident photon conversion efficiency (IPCE) from 16% (planar structure) to 42% (@ wavelength = 400 nm). More significantly, the turn-on voltage is reduced low to -0.6 V, which indicates the possibility of achieving self-driven. Furthermore, SiO2/Si3N4 dielectric distributed Bragg reflectors are employed to further improve the IPCE up to 60%. And the photocurrent (@ 1.1 V) is enhanced from 0.37 mA/cm2 (original planar structure) to 1.5 mA/cm2. These improvements may accelerate the possible applications for hydrogen generation with high energy-efficiency.

  6. A high stability Ni-La0.5Ce0.5O2-δ asymmetrical metal-ceramic membrane for hydrogen separation and generation

    Science.gov (United States)

    Zhu, Zhiwen; Sun, Wenping; Wang, Zhongtao; Cao, Jiafeng; Dong, Yingchao; Liu, Wei

    2015-05-01

    In this work, hydrogen permeation properties of Ni-La0.5Ce0.5O2-δ (LDC) asymmetrical cermet membrane are investigated, including hydrogen fluxes (JH2) under different hydrogen partial pressures, the influence of water vapor on JH2 and the long-term stability of the membrane operating under the containing-CO2 atmosphere. Ni-LDC asymmetrical membrane shows the best hydrogen permeability among LDC-based hydrogen separation membranes, inferior to Ni-BaZr0.1Ce0.7Y0.2O3-δ asymmetrical membrane. The water vapor in feed gas is beneficial to hydrogen transport process, which promote an increase of JH2 from 5.64 × 10-8 to 6.83 × 10-8 mol cm-2 s-1 at 900 °C. Stability testing of hydrogen permeation suggests that Ni-LDC membrane remains stable against CO2. A dual function of combining hydrogen separation and generation can be realized by humidifying the sweep gas and enhance the hydrogen output by 1.0-1.5 times. Ni-LDC membrane exhibits desirable performance and durability in dual-function mode. Morphologies and phase structures of the membrane after tests are also characterized by SEM and XRD.

  7. Hanford waste vitrification plant hydrogen generation study: Preliminary evaluation of alternatives to formic acid

    International Nuclear Information System (INIS)

    Oxalic, glyoxylic, glycolic, malonic, pyruvic, lactic, levulinic, and citric acids as well as glycine have been evaluated as possible substitutes for formic acid in the preparation of feed for the Hanford waste vitrification plant using a non-radioactive feed stimulant UGA-12M1 containing substantial amounts of aluminum and iron oxides as well as nitrate and nitrite at 90C in the presence of hydrated rhodium trichloride. Unlike formic acid none of these carboxylic acids liberate hydrogen under these conditions and only malonic and citric acids form ammonia. Glyoxylic, glycolic, malonic, pyruvic, lactic, levulinic, and citric acids all appear to have significant reducing properties under the reaction conditions of interest as indicated by the observation of appreciable amounts of N2O as a reduction product of,nitrite or, less likely, nitrate at 90C. Glyoxylic, pyruvic, and malonic acids all appear to be unstable towards decarboxylation at 90C in the presence of Al(OH)3. Among the carboxylic acids investigated in this study the α-hydroxycarboxylic acids glycolic and lactic acids appear to be the most interesting potential substitutes for formic acid in the feed preparation for the vitrification plant because of their failure to produce hydrogen or ammonia or to undergo decarboxylation under the reaction conditions although they exhibit some reducing properties in feed stimulant experiments

  8. Catalytic hydro desulphurization study of heavy petroleum residue through in situ generated hydrogen

    International Nuclear Information System (INIS)

    Hydrodesulphurization of heavy residue was carried out using various catalysts in the presence of co-reactants as the internal sources of hydrogen. Reactions were carried out in a micro autoclave at 320 deg. C and 10 kg f/cm2 pressure inert atmosphere of N2 for 3 h reaction time. Tetralin, propane, methanol, ethylene glycol and formic acid were separately used as co-reactants as hydrogen donors. Among the solvents studied, methanol gave the highest hydrodesulphurization yield (52%). The reaction was then carried out in the presence of various catalysts to view the influence of each individual catalyst on the desulphurization yield under the same conditions of pressure and temperature. The catalysts used were Mo-Montmorillonite, Co-Montmorillonite, nickel oxide (NiO), cadmium oxide (CdO), Zn-ZSM5, kaolin and montmorillonite clays. The results show that all the catalysts exhibited desulphurization activity. In case of Mo-Montmorillonite and Co-Montmorillonite charges, the desulfurization yields of 63% and 46% were obtained, respectively. NiO, CdO, Zn-ZSM5, kaolin and montmorillonite clays gave desulphurization yields of 54%, 50%, 56%, 20% and 36%, respectively. The desulphurization activities of Mo-Montmorillonite and Co-Montmorillonite were compared with other catalysts used. The results show that Mo-Montmorillonite gave the highest hydrodesulphurization yield. FTIR studies also confirmed the hydrodesulphurization efficiency of the Mo-Montmorillonite.

  9. Global Assessment of Hydrogen Technologies – Task 5 Report Use of Fuel Cell Technology in Electric Power Generation

    Energy Technology Data Exchange (ETDEWEB)

    Fouad, Fouad H.; Peters, Robert W.; Sisiopiku, Virginia P.; Sullivan Andrew J.; Ahluwalia, Rajesh K.

    2007-12-01

    The purpose of this work was to assess the performance of high temperature membranes and observe the impact of different parameters, such as water-to-carbon ratio, carbon formation, hydrogen formation, efficiencies, methane formation, fuel and oxidant utilization, sulfur reduction, and the thermal efficiency/electrical efficiency relationship, on fuel cell performance. A 250 KW PEM fuel cell model was simulated [in conjunction with Argonne National Laboratory (ANL) with the help of the fuel cell computer software model (GCtool)] which would be used to produce power of 250 kW and also produce steam at 120oC that can be used for industrial applications. The performance of the system was examined by estimating the various electrical and thermal efficiencies achievable, and by assessing the effect of supply water temperature, process water temperature, and pressure on thermal performance. It was concluded that increasing the fuel utilization increases the electrical efficiency but decreases the thermal efficiency. The electrical and thermal efficiencies are optimum at ~85% fuel utilization. The low temperature membrane (70oC) is unsuitable for generating high-grade heat suitable for useful cogeneration. The high temperature fuel cells are capable of producing steam through 280oC that can be utilized for industrial applications. Increasing the supply water temperature reduces the efficiency of the radiator. Increasing the supply water temperature beyond the dew point temperature decreases the thermal efficiency with the corresponding decrease in high-grade heat utilization. Increasing the steam pressure decreases the thermal efficiency. The environmental impacts of fuel cell use depend upon the source of the hydrogen rich fuel used. By using pure hydrogen, fuel cells have virtually no emissions except water. Hydrogen is rarely used due to problems with storage and transportation, but in the future, the growth of a “solar hydrogen economy” has been projected

  10. Hydrogen generation during treatment of simulated high-level radioactive waste with formic acid

    Energy Technology Data Exchange (ETDEWEB)

    Ritter, J.A.; Zamecnik, J.R.; Hsu, C.W.

    1992-05-01

    The Integrated Defense Waste Processing Facility (DWPF) Melter System (IDMS), operated by the Savannah River Laboratory, is a one-fifth scale pilot facility used in support of the start-up and operation of the Department of Energy`s DWPF. Five IDMS runs determined the effect of the presence of noble metals in HLW sludge on the H{sub 2} generation rate during the preparation of melter feed with formic acid. Overall, the results clearly showed that H{sub 2} generation in the DWPF SRAT could, at times, exceed the lower flammable limit of H{sub 2} in air (4 vol%), depending on such factors as offgas generation and air inleakage of the DWPF vessels. Therefore, the installation of a forced air purge system and H{sub 2} monitors were recommended to the DWPF to control the generation of H{sub 2} during melter feed preparation by fuel dilution.

  11. Hydrogen generation during treatment of simulated high-level radioactive waste with formic acid

    Energy Technology Data Exchange (ETDEWEB)

    Ritter, J.A.; Zamecnik, J.R.; Hsu, C.W.

    1992-01-01

    The Integrated Defense Waste Processing Facility (DWPF) Melter System (IDMS), operated by the Savannah River Laboratory, is a one-fifth scale pilot facility used in support of the start-up and operation of the Department of Energy's DWPF. Five IDMS runs determined the effect of the presence of noble metals in HLW sludge on the H{sub 2} generation rate during the preparation of melter feed with formic acid. Overall, the results clearly showed that H{sub 2} generation in the DWPF SRAT could, at times, exceed the lower flammable limit of H{sub 2} in air (4 vol%), depending on such factors as offgas generation and air inleakage of the DWPF vessels. Therefore, the installation of a forced air purge system and H{sub 2} monitors were recommended to the DWPF to control the generation of H{sub 2} during melter feed preparation by fuel dilution.

  12. ASSESSMENT OF THE POTENTIAL FOR HYDROGEN GENERATION DURING GROUTING OPERATIONS IN THE R AND P REACTOR VESSELS

    Energy Technology Data Exchange (ETDEWEB)

    Wiersma, B.

    2010-05-24

    operations in the R-reactor vessel is low for the Portland cement. Alternatively, if the grout fill rate is less than 0.5 inch/min and the grout is maintained at a temperature of 80 C, the risk is again low. Although these calculations are conservative, there are some measures that may be taken to further minimize the potential for hydrogen evolution. (1) Minimize the temperature of the grout as much as practical. Lower temperatures will mean lower hydrogen generation rates. For P-reactor, grout temperatures less than 100 C should provide an adequate safety margin for the pH 8 and pH 10.4 grout formulations. For R-reactor, grout temperatures less than 70 C or 80 C will provide an adequate safety margin for the Portland cement. The other grout formulations are also viable options for R-reactor. (2) Minimize the grout fill rate as much as practical. Lowering the fill rate takes advantage of passivation of the aluminum components and hence lower hydrogen generation rates. For P-reactor, fill rates that are less than 2 inches/min for the ceramicrete and the silica fume grouts will reduce the chance of significant hydrogen accumulation. For R-reactor, fill rates less than 1 inch/min will again minimize the risk of hydrogen accumulation. (3) Ventilate the building as much as practical (e.g., leave doors open) to further disperse hydrogen. The volumetric hydrogen generation rates in the P-reactor vessel, however, are low for the pH 8 and pH 10.4 grout, (i.e., less than 0.97 ft{sup 3}/min). If further walk-down inspections of the reactor vessels suggest an increase in the actual areal density of aluminum, the calculations should be re-visited.

  13. Hydrodynamic analysis of a three-fluidized bed reactor cold flow model for chemical looping hydrogen generation. Pressure characteristics

    Energy Technology Data Exchange (ETDEWEB)

    Xue, Zhipeng; Xiang, Wenguo; Chen, Shiyi; Wang, Dong [Southeast Univ., Nanjing (China). School of Energy and Environment

    2013-07-01

    Chemical looping hydrogen generation (CLHG) can produce pure hydrogen with inherent separation of CO{sub 2} from fossils fuel. The process involves a metal oxide, as an oxygen carrier, such as iron oxide. The CLHG system consists of three reactors: a fuel reactor (FR), a steam reactor (SR) and an air reactor (AR). In the FR, the fuel gases react with iron oxides (hematite Fe{sub 2}O{sub 3}, magnetite Fe{sub 3}O{sub 4}, wuestite FeO), generating reduced iron oxides (FeO or even Fe), and with full conversion of gaseous fuels, pure CO{sub 2} can be obtained after cooling the flue gas from the fuel reactor; in the SR, FeO and Fe reacts with steam to generate magnetite (Fe{sub 3}O{sub 4}) and H{sub 2}, the latter representing the final target product of the process; in the AR, the magnetite is oxidized back to hematite which is used in another cycle. A cold flow model of three-fluidized bed for CLHG corresponding to 50 KW hot units has been built. A major novelty of this facility is the compact fuel reactor, which integrates a bubble and a fast fluidized bed to avoid the incomplete conversion of the fuel gas caused by the thermodynamics equilibrium. In order to study the pressure characteristics and the solids concentration of the system, especially in the fuel reactor, the gas velocity of three reactors, gas flow of L-type value, total solids inventory (TSI) and the secondary air of fuel reactor were varied. Results show that the pressure and the solids concentration are strongly influenced by the fluidizing-gas velocity of three reactors. Moreover, the entrainment of the upper part of fuel reactor increases as the total solids inventory increases, and the operating range of the FR can be changed by introducing secondary air or increasing the total solids inventory.

  14. Polyacrylonitrile Fibers Anchored Cobalt/Graphene Sheet Nanocomposite: A Low-Cost, High-Performance and Reusable Catalyst for Hydrogen Generation.

    Science.gov (United States)

    Zhang, Fei; Huang, Guoji; Hou, Chengyi; Wang, Hongzhi; Zhang, Qinghong; Li, Yaogang

    2016-06-01

    Cobalt and its composites are known to be active and inexpensive catalysts in sodium borohydride (NaBH4) hydrolysis to generate clean and renewable hydrogen energy. A novel fiber catalyst, cobalt/graphene sheet nanocomposite anchored on polyacrylonitrile fibers (Co/GRs-PANFs), which can be easily recycled and used in any reactor with different shapes, were synthesized by anchoring cobalt/graphene (Co/GRs) on polyacrylonitrile fibers coated with graphene (GRs-PANFs) at low temperature. The unique structure design effectively prevents the inter-sheet restacking of Co/GRs and fully exploits the large surface area of novel hybrid material for generate hydrogen. And the extra electron transfer path supplied by GRs on the surface of GRs-PANFs can also enhance their catalysis performances. The catalytic activity of the catalyst was investigated by the hydrolysis of NaBH4 in aqueous solution with GRs-PANFs. GRs powders and Co powders were used as control groups. It was found that both GRs and fiber contributed to the hydrogen generation rate of Co/GRs-PANFs (3222 mL x min(-1) x g(-1)), which is much higher than that of cobalt powders (915 mL x min(-1) x g(-1)) and Co/GRs (995 mL x min(-1) x g(-1)). The improved hydrogen generation rate, low cost and uncomplicated recycling make the Co/GRs-PANFs promising candidate as catalysts for hydrogen generation. PMID:27427607

  15. Direct numerical simulation of hydrogen addition in turbulent premixed Bunsen flames using flamelet-generated manifold reduction

    Energy Technology Data Exchange (ETDEWEB)

    Vreman, A.W. [Combustion Technology, Department of Mechanical Engineering, Technische Universiteit Eindhoven, Den Dolech 2, P.O. Box 513, 5600 MB Eindhoven (Netherlands); Vreman Research, Godfried Bomansstraat 46, 7552 NT Hengelo (Netherlands); van Oijen, J.A.; de Goey, L.P.H.; Bastiaans, R.J.M. [Combustion Technology, Department of Mechanical Engineering, Technische Universiteit Eindhoven, Den Dolech 2, P.O. Box 513, 5600 MB Eindhoven (Netherlands)

    2009-03-15

    Direct numerical simulations of a lean premixed turbulent Bunsen flame with hydrogen addition have been performed. We show the results for a case with equivalence ratio of 0.7 and a molar fractional distribution of 40% H{sub 2} and 60% CH{sub 4}. The flamelet-generated manifold technique is used to reduce the chemistry; flamelets with different equivalence ratios and inflow temperature are used to account for stretch effects that are enhanced by preferential diffusion. The three-dimensional simulation clearly shows enhanced burning velocity in regions convex toward the reactants and reduced burning velocity with possible extinction in regions concave toward the reactants. To obtain these effects it was found to be necessary to include two three-dimensional transport equations with essentially different diffusivities. This point is illustrated by comparison of the results with cases in which either a single transport equation was used or two transport equations with minor differences in diffusivities were used. These latter cases incorporated preferential diffusion in the 1D flamelets (and thus in the manifold), but not in the three-dimensional transport. Thus the three-dimensional preferential diffusion effects are shown to enhance curvature and thereby to increase the turbulent burning velocity and reduce the mean flame height. In addition the turbulent burning velocity increases because hydrogen addition leads to a larger laminar flamelet consumption speed. To demonstrate this second effect, results of the cases mentioned above are compared to the results of simulations of the Bunsen flame with 0% hydrogen added to the fuel. (author)

  16. Zeolite-confined ruthenium(0) nanoclusters catalyst: record catalytic activity, reusability, and lifetime in hydrogen generation from the hydrolysis of sodium borohydride.

    Science.gov (United States)

    Zahmakiran, Mehmet; Ozkar, Saim

    2009-03-01

    Sodium borohydride, NaBH4, has been considered the most attractive hydrogen-storage material for portable fuel cell applications, as it provides a safe and practical means of producing hydrogen. In a recent communication (Zahmakiran, M.; Ozkar, S. Langmuir 2008, 24, 7065), we have reported a record total turnover number (TTON) of 103 200 mol H2/mol Ru and turnover frequency (TOF) up to 33 000 mol H2/mol Ru x h obtained by using intrazeolite ruthenium(0) nanoclusters in the hydrolysis of sodium borohydride. Here we report full details of the kinetic studies on the intrazeolite ruthenium(0) nanoclusters catalyzed hydrolysis of sodium borohydride in both aqueous and basic solutions. Expectedly, the intrazeolite ruthenium(0) nanoclusters show unprecedented catalytic lifetime, TTON = 27 200 mol H2/mol Ru, and TOF up to 4000 mol H2/mol Ru x h in the hydrolysis of sodium borohydride in basic solution (5% wt NaOH) as well. More importantly, the intrazeolite ruthenium(0) nanoclusters are isolable, bottleable, redispersible, and yet catalytically active. They retain 76% or 61% of their initial catalytic activity at the fifth run with a complete release of hydrogen in aqueous and basic medium, respectively. The intrazeolite ruthenium(0) nanoclusters were isolated as black powder and characterized by using a combination of advanced analytical techniques including XRD, HRTEM, TEM-EDX, SEM, XPS, ICP-OES, and N2 adsorption. PMID:19437749

  17. Ammonium generation during SRAT cycle

    International Nuclear Information System (INIS)

    During the IDMS noble-metal demonstration runs ammonium nitrate deposition was found in the vessel vent system of the feed preparation area. In the bench-scale experiments of studying the hydrogen generation during the sludge treatment cycle, ammonium ion production was also monitored. It was found that: During a simulation of the DWPF Cold Chemical Runs SRAT cycle no detectable amount of ammonium ions was generated when treating a non-noble-metal containing sludge simulant according to the nitric acid flowsheet. Ammonium ions were generated during the SRAT-SME cycle when treating the noble-metal containing sludge with either formic acid or nitric acid/late-washing PHA. This is due to the reaction between formic acid and nitrate catalyzed by the noble metals in the sludge simulant. Ammonium ion production closely followed the hydrogen evolution from the catalytic decomposition of formic acid. This report summarizes the results of the production of ammonia during the SRAT cycle

  18. In Situ Fluorine Doping of TiO2 Superstructures for Efficient Visible-Light Driven Hydrogen Generation.

    Science.gov (United States)

    Zhang, Peng; Tachikawa, Takashi; Fujitsuka, Mamoru; Majima, Tetsuro

    2016-03-21

    With the aid of breakthroughs in nanoscience and nanotechnology, it is imperative to develop metal oxide semiconductors through visible light-driven hydrogen generation. In this study, TiOF2 was incorporated as an n-type F-dopant source to TiO2 mesocrystals (TMCs) with visible-light absorption during the topotactic transformation. The crystal growth, structural change, and dynamic morphological evolution, from the initial intermediate NH4 TiOF3 to HTiOF3 , TiOF2 , and F-doped TMCs, were verified through in situ temperature-dependent techniques to elucidate the doping mechanism from intermediate TiOF2 . The visible-light efficiencies of photocatalytic hydrogen were dependent on the contents of the dopant as compared with the pure TMC and a controled reference. Using femtosecond time-resolved diffuse reflectance spectroscopy, the charge-transfer dynamics were monitored to confirm the improvement of charge separation after doping. PMID:26871554

  19. Comparison of hydrogen generation for TVSM and TVSA fuel assemblies for water water energy reactor (VVER)-1000

    Energy Technology Data Exchange (ETDEWEB)

    Stefanova, A.E. [Institute for Nuclear Research and Nuclear Energy, Bulgarian Academy of Sciences, Tzarigradsko Shaussee 72, Sofia 1784 (Bulgaria)], E-mail: antoanet@inrne.bas.bg; Groudev, P.P. [Institute for Nuclear Research and Nuclear Energy, Bulgarian Academy of Sciences, Tzarigradsko Shaussee 72, Sofia 1784 (Bulgaria)], E-mail: pavlinpg@inrne.bas.bg; Atanasova, B.P. [Institute for Nuclear Research and Nuclear Energy, Bulgarian Academy of Sciences, Tzarigradsko Shaussee 72, Sofia 1784 (Bulgaria)], E-mail: b_atanasova@inrne.bas.bg

    2009-01-15

    This paper presents the results received during investigation of hydrogen generation for both types fuel assemblies-the old modernistic type of fuel assemblies (TVSM) and recently installed new one alternative type of fuel assemblies (TVSA) in case of severe accident. There are some differences between both types FAs. They have different geometry as well as different burnable poisons. To investigate behavior of new fuel assemblies during the severe conditions it have been performed comparison of fuel behavior of old type TVSM fuel assembly to new one TVSA. To perform this investigation it has been used MELCOR 'input model' for Kozloduy Nuclear Power Plant (KNPP) VVER 1000. The model was developed by Institute for Nuclear Research and Nuclear Energy-Bulgarian Academy of Sciences (INRNE-BAS) for investigation of severe accident scenarios and Probabilistic Safety Analyses (PSA) level 2. The model provides a significant analytical capability for the Bulgarian technical specialists, working in the field of the NPP safety, for analysis of core and containment damaged states and the estimation of radionuclides release outside fuel cladding. It was accepted criteria for vessel integrity about hydrogen concentration to be 8%. This criterion was based on the decision of RSK (Germany commission for reactor safety). Generally based on the received results it was made conclusion that using both types of fuel assemblies it was not disturbance safety conditions of NPP.

  20. Tailoring the band structure of β-Bi2O3 by co-doping for realized photocatalytic hydrogen generation

    Science.gov (United States)

    Li, Min; Li, Feng; Yin, Peng Gang

    2014-05-01

    The electronic properties and optical properties of doped β-Bi2O3 have been studied using spin-polarized density function theory (DFT) with the aim of realizing the photocatalytic hydrogen generation under visible light irradiation. The results show that IIIA elements (Al, Ga, In and Tl) mono-doping increase the necessary redox potentials in energy for water splitting, but the increasing of band gap decreases the visible light absorption. Moreover, co-doping in β-Bi2O3 can overcome this problem by increasing the light absorption and simultaneously realizing water splitting by sunlight. The N/Al and N/Ga co-doped β-Bi2O3 introduce the delocalized band, which extend the light absorption but has limited benefit for photocatalytic activity. Importantly, N/In and N/Tl co-doping shift the mid-gap states toward the valence band edge to create an extend valence density of states, which can improve the light absorption. In particular, N/In co-doping leads to the narrowed band gap and a stronger potential for photocatalytic activity toward hydrogen evolution from water, which may play an important role in the development of bismuth oxides for more effective utilization of the solar spectrum for fuel production.

  1. Comparison of hydrogen generation for TVSM and TVSA fuel assemblies for water water energy reactor (VVER)-1000

    International Nuclear Information System (INIS)

    This paper presents the results received during investigation of hydrogen generation for both types fuel assemblies-the old modernistic type of fuel assemblies (TVSM) and recently installed new one alternative type of fuel assemblies (TVSA) in case of severe accident. There are some differences between both types FAs. They have different geometry as well as different burnable poisons. To investigate behavior of new fuel assemblies during the severe conditions it have been performed comparison of fuel behavior of old type TVSM fuel assembly to new one TVSA. To perform this investigation it has been used MELCOR 'input model' for Kozloduy Nuclear Power Plant (KNPP) VVER 1000. The model was developed by Institute for Nuclear Research and Nuclear Energy-Bulgarian Academy of Sciences (INRNE-BAS) for investigation of severe accident scenarios and Probabilistic Safety Analyses (PSA) level 2. The model provides a significant analytical capability for the Bulgarian technical specialists, working in the field of the NPP safety, for analysis of core and containment damaged states and the estimation of radionuclides release outside fuel cladding. It was accepted criteria for vessel integrity about hydrogen concentration to be 8%. This criterion was based on the decision of RSK (Germany commission for reactor safety). Generally based on the received results it was made conclusion that using both types of fuel assemblies it was not disturbance safety conditions of NPP

  2. Estimate Of The Decay Rate Constant of Hydrogen Sulfide Generation From Landfilled Drywall

    Science.gov (United States)

    Research was conducted to investigate the impact of particle size on H2S gas emissions and estimate a decay rate constant for H2S gas generation from the anaerobic decomposition of drywall. Three different particle sizes of regular drywall and one particle size of paperless drywa...

  3. Hydrogen economy

    Energy Technology Data Exchange (ETDEWEB)

    Pahwa, P.K.; Pahwa, Gulshan Kumar

    2013-10-01

    In the future, our energy systems will need to be renewable and sustainable, efficient and cost-effective, convenient and safe. Hydrogen has been proposed as the perfect fuel for this future energy system. The availability of a reliable and cost-effective supply, safe and efficient storage, and convenient end use of hydrogen will be essential for a transition to a hydrogen economy. Research is being conducted throughout the world for the development of safe, cost-effective hydrogen production, storage, and end-use technologies that support and foster this transition. This book discusses hydrogen economy vis-a-vis sustainable development. It examines the link between development and energy, prospects of sustainable development, significance of hydrogen energy economy, and provides an authoritative and up-to-date scientific account of hydrogen generation, storage, transportation, and safety.

  4. Between photocatalysis and photosynthesis: Synchrotron spectroscopy methods on molecules and materials for solar hydrogen generation

    International Nuclear Information System (INIS)

    Highlights: ► We provide a series of soft X-ray and nuclear resonant vibration spectroscopy experiments relevant for solar hydrogen production. ► Metal oxide photoelectrodes and photosynthesis protein motifs are investigated. ► Ex situ and photoelectrochemical in situ studies are presented. ► The relevant role of defect states on surfaces, in sub-surfaces and in the bulk is elucidated. -- Abstract: Energy research is to a large extent materials research, encompassing the physics and chemistry of materials, including their synthesis, processing toward components and design toward architectures, allowing for their functionality as energy devices, extending toward their operation parameters and environment, including also their degradation, limited life, ultimate failure and potential recycling. In all these stages, X-ray and electron spectroscopy are helpful methods for analysis, characterization and diagnostics for the engineer and for the researcher working in basic science. This paper gives a short overview of experiments with X-ray and electron spectroscopy for solar energy and water splitting materials and addresses also the issue of solar fuel, a relatively new topic in energy research. The featured systems are iron oxide and tungsten oxide as photoanodes, and hydrogenases as molecular systems. We present surface and sub-surface studies with ambient pressure XPS and hard X-ray XPS, resonant photoemission, light induced effects in resonant photoemission experiments and a photo-electrochemical in situ/operando NEXAFS experiment in a liquid cell, and nuclear resonant vibrational spectroscopy (NRVS)

  5. CoP nanosheet assembly grown on carbon cloth: A highly efficient electrocatalyst for hydrogen generation

    KAUST Repository

    Yang, Xiulin

    2015-07-01

    There exists a strong demand to replace expensive noble metal catalysts with cheap metal sulfides or phosphides for hydrogen evolution reaction (HER). Recently metal phosphides such as NixP, FeP and CoP have been considered as promising candidates to replace Pt cathodes. Here we report that the nanocrystalline CoP nanosheet assembly on carbon cloth can be formed by a two-step process: electrochemical deposition of Co species followed by gas phase phosphidation. The CoP catalyst in this report exhibits a Tafel slope of 30.1mV/dec in 0.5M H2SO4 and 42.6mV/dec in 1M KOH. The high HER performance of our CoP catalysts is attributed to the rugae-like morphology which results in a high double-layer capacitance and high density of active sites, estimated as 7.77×1017sites/cm2. © 2015 Elsevier Ltd.

  6. A Visible-Light-Active Heterojunction with Enhanced Photocatalytic Hydrogen Generation.

    Science.gov (United States)

    Adhikari, Shiba P; Hood, Zachary D; More, Karren L; Chen, Vincent W; Lachgar, Abdou

    2016-07-21

    A visible-light-active carbon nitride (CN)/strontium pyroniobate (SNO) heterojunction photocatalyst was fabricated by deposition of CN over hydrothermally synthesized SNO nanoplates by a simple thermal decomposition process. The microscopic study revealed that nanosheets of CN were anchored to the surface of SNO resulting in an intimate contact between the two semiconductors. Diffuse reflectance UV/Vis spectra show that the resulting CN/SNO heterojunction possesses intense absorption in the visible region. The structural and spectral properties endowed the CN/SNO heterojunction with remarkably enhanced photocatalytic activity. Specifically, the photocatalytic hydrogen evolution rate per mole of CN was found to be 11 times higher for the CN/SNO composite compared to pristine CN. The results clearly show that the composite photocatalyst not only extends the light absorption range of SNO but also restricts photogenerated charge-carrier recombination, resulting in significant enhancement in photocatalytic activity compared to pristine CN. The relative band positions of the composite allow the photogenerated electrons in the conduction band of CN to migrate to that of SNO. This kind of charge migration and separation leads to the reduction in the overall recombination rate of photogenerated charge carriers, which is regarded as one of the key factors for the enhanced activity. A plausible mechanism for the enhanced photocatalytic activity of the heterostructured composite is proposed based on observed activity, photoluminescence, time-resolved fluorescence emission decay, electrochemical impedance spectroscopy, and band position calculations. PMID:27282318

  7. Synthesis of Cr2O3/TNTs nanocomposite and its photocatalytic hydrogen generation under visible light irradiation

    International Nuclear Information System (INIS)

    A novel Cr2O3/TNTs nanocomposite was prepared by loaded suitable amount of amorphous Cr2O3 on titanate nanotubes (TNTs) via hydrothermal reaction and impregnation process. XRD, SEM and TEM results demonstrated that the amorphous Cr2O3 nanoparticles were homogeneously dispersed on the surface of TNTs. The diffuse reflectance UV-visible absorption spectra exhibited that the spectral response of TNTs was extended to visible light region by coupled with Cr2O3. The 2.5Cr2O3/TNTs nanocomposite showed the highest activity of hydrogen generation by photocatalytic water-splitting under visible light irradiation (λ > 400 nm). The high activity of H2 evolution for Cr2O3/TNTs nanocomposites was associated with the donor level in the forbidden band of TNTs semiconductor provided by dopant Cr3+ and a probably photocatalytic mechanism was proposed.

  8. The hydrogen generation from alkaline NaBH4 solution by using electroplated amorphous Co–Ni–P film catalysts

    International Nuclear Information System (INIS)

    The amorphous Co–Ni–P films were electroplating on Cu sheets. The effects of NiSO4 concentrations on the deposit plating rate and the catalytic activities for NaBH4 hydrolysis were investigated. The surface morphology and phase structure of the deposited Co–Ni–P films were characterized by scanning electron microscopy (SEM) and X-ray diffraction (XRD) analysis. The composition was analyzed by energy dispersive spectrometer (EDX). Experimental results showed that adding NiSO4 in Co–P bath could increase the deposition rate. When 0.01 M of NiSO4 was used, the highest deposition rate and the highest hydrogen generation rate of 3636 mL (min g-catalyst)−1 were obtained. The activation energy (Ea) for the NaBH4 hydrolysis was 38 kJ mol−1, which was comparable to the value of noble metal catalysts.

  9. Contribution to the modelling of reversible electrolyser and hydrogen fuel cell for coupling to the photovoltaic generators

    International Nuclear Information System (INIS)

    A response to concerns raised by an energy mix which mainly consists of exhaustible fossil fuels harmful to the environment is to gradually substitute them by renewable energy sources, including solar or wind power. However, these intermittent flow energies set a recovery problem. They are often the source of electricity which inherits their fluctuations, which requires a transport network and which is an energy carrier not easy to store. In this context hydrogen synthesized from this renewable electricity, storing, it is considered as a stock carrier promising for the future. Various components and electrochemical processes are associated with this perspective: electrolysers, fuel cells, associations of these two functions combined in the system or integrated into a unitised reversible component. Our work is set in this perspective. It contributed to the development of advanced models of electrochemical components of electrolyser or fuel cells type, integrating reversibility for the study of their coupling to the photovoltaic generators. The models developed following a unified energetic approach use bond graph representation. After an analysis of the energy context, a state of the art of electrochemical components coupling hydrogen and electricity is presented, particularly on electrolysers and regenerative or unitised reversible fuel cells. Then, after a reminder of the principles of the Bond Graph representation, we exploit this formalism to develop an energetic model of a reversible component 'electrolyser and / or fuel cell' representative at macroscopic level of conversion reaction and dissipation phenomena, coupled in chemical, thermodynamic, electrical, thermal and fluid fields. Tests for characterization and validation conducted on small experimental devices are then described. They can illustrate the influence of operating parameters on the performance of these components. Finally, the Bond Graph model is used to study the modularity of components

  10. Nitrogen and cobalt co-doped zinc oxide nanowires - Viable photoanodes for hydrogen generation via photoelectrochemical water splitting

    Science.gov (United States)

    Patel, Prasad Prakash; Hanumantha, Prashanth Jampani; Velikokhatnyi, Oleg I.; Datta, Moni Kanchan; Hong, Daeho; Gattu, Bharat; Poston, James A.; Manivannan, Ayyakkannu; Kumta, Prashant N.

    2015-12-01

    Photoelectrochemical (PEC) water splitting has been considered as a promising and environmentally benign approach for efficient and economic hydrogen generation by utilization of solar energy. Development of semiconductor materials with low band gap, high photoelectrochemical activity and stability has been of particular interest for a viable PEC water splitting system. In this study, Co doped ZnO, .i.e., (Zn0.95Co0.05)O nanowires (NWs) was selected as the composition for further co-doping with nitrogen by comparing solar to hydrogen efficiency (SHE) of ZnO NWs with that of various compositions of (Zn1-xCox)O NWs (x = 0, 0.05, 0.1). Furthermore, nanostructured vertically aligned Co and N-doped ZnO, .i.e., (Zn1-xCox)O:N NWs (x = 0.05) have been studied as photoanodes for PEC water splitting. An optimal SHE of 1.39% the highest reported so far to the best of our knowledge for ZnO based photoanodes was obtained for the co-doped NWs, (Zn0.95Co0.05)O:N - 600 NWs generated at 600 °C in ammonia atmosphere. Further, (Zn0.95Co0.05)O:N-600 NWs exhibited excellent photoelectrochemical stability under illumination compared to pure ZnO NWs. These promising results suggest the potential of (Zn0.95Co0.05)O:N-600 NWs as a viable photoanode in PEC water splitting cell. Additionally, theoretical first principles study conducted explains the beneficial effects of Co and N co-doping on both, the electronic structure and the band gap of ZnO.

  11. Self-Sensitized Carbon Nitride Microspheres for Long-Lasting Visible-Light-Driven Hydrogen Generation.

    Science.gov (United States)

    Gu, Quan; Gao, Ziwei; Xue, Can

    2016-07-01

    A new type of metal-free photocatalyst is reported having a microsphere core of oxygen-containing carbon nitride and self-sensitized surfaces by covalently linked polymeric triazine dyes. These self-sensitized carbon nitride microspheres exhibit high visible-light activities in photocatalytic H2 generation with excellent stability for more than 100 h reaction. Comparing to the traditional g-C3 N4 with activities terminated at 450 nm, the polymeric triazine dyes on the carbon nitride microsphere surface allow for effective wide-range visible-light harvesting and extend the H2 generation activities up to 600 nm. It is believed that this new type of highly stable self-sensitized metal-free structure opens a new direction of future development of low-cost photocatalysts for efficient and long-term solar fuels production. PMID:27225827

  12. Method and apparatus for hydrogen production from water

    Science.gov (United States)

    Muradov, Nazim Z. (Inventor)

    2012-01-01

    A method, apparatuses and chemical compositions are provided for producing high purity hydrogen from water. Metals or alloys capable of reacting with water and producing hydrogen in aqueous solutions at ambient conditions are reacted with one or more inorganic hydrides capable of releasing hydrogen in aqueous solutions at ambient conditions, one or more transition metal compounds are used to catalyze the reaction and, optionally, one or more alkali metal-based compounds. The metal or alloy is preferably aluminum. The inorganic hydride is from a family of complex inorganic hydrides; most preferably, NaBH.sub.4. The transition metal catalyst is from the groups VIII and IB; preferably, Cu and Fe. The alkali metal-based compounds are preferably NaOH, KOH, and the like. Hydrogen generated has a purity of at least 99.99 vol. % (dry basis), and is used without further purification in all types of fuel cells, including the polymer electrolyte membrane (PEM) fuel cell.

  13. Parameters critical to muon-catalyzed fusion

    International Nuclear Information System (INIS)

    We have demonstrated that muon catalysis cycling rates increase rapidly with increasing deuterium-tritium gas temperatures and densities. Furthermore, muon-capture losses are significantly smaller than predicted before the experiments. There remains a significant gap between observation and theoretical expectation for the muon-alpha sticking probability in dense d-t mixtures. We have been able to achieve muon-catalyzed yields of 150 fusion/muon (average). While the fusion energy thereby released significantly exceeds expectations, enhancements by nearly a factor of twenty would be needed to realize energy applications for a pure (non-hybrid) muon-catalyzed fusion reactor. The process could be useful in tritium-breeding schemes. We have also explored a new form of cold nuclear fusion which occurs when hydrogen isotopes are loaded into metals. 22 refs., 10 figs

  14. Separation of beds by hydrogen-content using gamma-generator

    International Nuclear Information System (INIS)

    The possibility of using the D12(γ,n)H11 reaction for classifying media according to the hydrogen content was studied experimentally. The model of the stratum is a 560-mm-dia, 850-mm-high reservoir filled with quartz sand with a water saturation of 5.5, 12.5, or 45%. The gamma bremstrahlung source is the FIAN M-1 microtron. The current at the 0.1-mm-thick tungsten target is 10 mA per pulse. The pulse frequency is 100 Hz and its length, 3 μsec. The gamma bremstrahlung is monitored with a thick-wall ionization chamber with an operating volume of 20 cm3. The SNM-2 neutron counter is located on the vertical axis of the model, 20 cm from the axis of the gamma bremstrahlung collimated beam. To prevent overloading, the measuring apparatus is started up with a 40-μsec lag with a time-window width of 1150 μsec. Gamma bremstrahlung energies of 6.5 and 7.5 MeV were used. The maximum energy level is provided by a stabilization scheme, with a precision of +- 0.1 MeV. The relative mean square error of the measurements is no more than 3-5%. The dependence of the photoneutron density on moisture was close to linear, and the differential coefficient with Esub(max)=6.5 MeV for a medium with 45 or 5% moisture was close to 8. Gamma radiation with energies no greater than 4.14 MeV should be used in order to exclude secondary reactions, and measurement of time distribution of the photoneutron flux is feasible

  15. ROLE OF COPPER,ZINC-SUPEROXIDE DISMUTASE IN CATALYZING NITROTYROSINE FORMATION IN MURINE LIVER

    Science.gov (United States)

    The solely known function of Cu,Zn-superoxide dismutase (SOD1) is to catalyze the dismutation of superoxide anion into hydrogen peroxide. Our objective was to determine if SOD1 catalyzed murine liver protein nitration induced by acetaminophen (APAP) and lipopolysaccharide (LPS). Liver and plasma ...

  16. Hydrogen generation and storage system using sodium borohydride at high pressures for operation of a 100 W-scale PMF stack

    OpenAIRE

    M.J.F. Ferreira; Rangel, C. M.; Pinto, A. M. F. R.

    2008-01-01

    A study is reported on the generation and storage of hydrogen from sodium borohydride (NaBH4) solutions in batch reactors, under pressures up to 4 MPa, in the presence of an improved and reused non-noble nickel-based powered catalyst. It follows references [1-10]. The first two purposes of the present work were to study the influence of the solution medium in the volume of hydrogen generated by hydrolysis of NaBH4, with a specific interest in: (1) comparing the performance of water and viscou...

  17. Iridium-Catalyzed Selective Isomerization of Primary Allylic Alcohols.

    Science.gov (United States)

    Li, Houhua; Mazet, Clément

    2016-06-21

    This Account presents the development of the iridium-catalyzed isomerization of primary allylic alcohols in our laboratory over the past 8 years. Our initial interest was driven by the long-standing challenge associated with the development of a general catalyst even for the nonasymmetric version of this seemingly simple chemical transformation. The added value of the aldehyde products and the possibility to rapidly generate molecular complexity from readily accessible allylic alcohols upon a redox-economical isomerization reaction were additional sources of motivation. Certainly influenced by the success story of the related isomerization of allylic amines, most catalysts developed for the selective isomerization of allylic alcohols were focused on rhodium as a transition metal of choice. Our approach has been based on the commonly accepted precept that hydrogenation and isomerization are often competing processes, with the latter being usually suppressed in favor of the former. The cationic iridium complexes [(Cy3P)(pyridine)Ir(cod)]X developed by Crabtree (X = PF6) and Pfaltz (X = BArF) are usually considered as the most versatile catalysts for the hydrogenation of allylic alcohols. Using molecular hydrogen to generate controlled amounts of the active form of these complexes but performing the reaction in the absence of molecular hydrogen enabled deviation from the typical hydrogenation manifold and favored exclusively the isomerization of allylic alcohols into aldehydes. Isotopic labeling and crossover experiments revealed the intermolecular nature of the process. Systematic variation of the ligand on the iridium center allowed us to identify the structural features beneficial for catalytic activity. Subsequently, three generations of chiral catalysts have been investigated and enabled us to reach excellent levels of enantioselectivity for a wide range of 3,3-disubstituted aryl/alkyl and alkyl/alkyl primary allylic alcohols leading to β-chiral aldehydes. The

  18. Hydrogen peroxide generation by higher plant mitochondria oxidizing complex I or complex II substrates.

    Science.gov (United States)

    Braidot, E; Petrussa, E; Vianello, A; Macri, F

    1999-05-28

    The generation of H2O2 by isolated pea stem mitochondria, oxidizing either malate plus glutamate or succinate, was examined. The level of H2O2 was almost one order of magnitude higher when mitochondria were energized by succinate. The succinate-dependent H2O2 formation was abolished by malonate, but unaffected by rotenone. The lack of effect of the latter suggests that pea mitochondria were working with a proton motive force below the threshold value required for reverse electron transfer. The activation by pyruvate of the alternative oxidase was reflected in an inhibition of H2O2 formation. This effect was stronger when pea mitochondria oxidized malate plus glutamate. Succinate-dependent H2O2 formation was ca. four times lower in Arum sp. mitochondria (known to have a high alternative oxidase) than in pea mitochondria. An uncoupler (FCCP) completely prevented succinate-dependent H2O2 generation, while it only partially (40-50%) inhibited that linked to malate plus glutamate. ADP plus inorganic phosphate (transition from state 4 to state 3) also inhibited the succinate-dependent H2O2 formation. Conversely, that dependent on malate plus glutamate oxidation was unaffected by low and stimulated by high concentrations of ADP. These results show that the main bulk of H2O2 is formed during substrate oxidation at the level of complex II and that this generation may be prevented by either dissipation of the electrochemical proton gradient (uncoupling and transition state 4-state 3), or preventing its formation (alternative oxidase). Conversely, H2O2 production, dependent on oxidation of complex I substrate, is mainly lowered by the activation of the alternative oxidase. PMID:10371218

  19. Temperature trends for reaction rates, hydrogen generation, and partitioning of iron during experimental serpentinization of olivine

    Science.gov (United States)

    McCollom, Thomas M.; Klein, Frieder; Robbins, Mark; Moskowitz, Bruce; Berquó, Thelma S.; Jöns, Niels; Bach, Wolfgang; Templeton, Alexis

    2016-05-01

    A series of laboratory experiments were conducted to examine how partitioning of Fe among solid reaction products and rates of H2 generation vary as a function of temperature during serpentinization of olivine. Individual experiments were conducted at temperatures ranging from 200 to 320 °C, with reaction times spanning a few days to over a year. The extent of reaction ranged from brucite, and magnetite, with minor amounts of magnesite, dolomite, and iowaite. The chrysotile contained only small amounts of Fe (XFe = 0.03-0.05, with ∼25% present as ferric Fe in octahedral sites), and displayed little variation in composition with reaction temperature. Conversely, the Fe contents of brucite (XFe = 0.01-0.09) increased steadily with decreasing reaction temperature. Analysis of the reaction products indicated that the stoichiometry of the serpentinization reactions varied with temperature, but remained constant with increasing reaction progress at a given temperature. The observed distribution of Fe among the reaction products does not appear to be entirely consistent with existing equilibrium models of Fe partitioning during serpentinization, suggesting improved models that include kinetic factors or multiple reaction steps need to be developed. Rates of H2 generation increased steeply from 200 to 300 °C, but dropped off at higher temperatures. This trend in H2 generation rates is attributable to a combination of the overall rate of serpentinization reactions and increased partitioning of Fe into brucite rather than magnetite at lower temperatures. The results suggest that millimolal concentration of H2 could be attained in moderately hot hydrothermal systems like Lost City during fluid circulation on timescales of a few years.

  20. Experimental Hydrogen Plant with Metal Hydrides to Store and Generate Electrical Power

    Science.gov (United States)

    Gonzatti, Frank; Nizolli, Vinícius; Ferrigolo, Fredi Zancan; Farret, Felix Alberto; de Mello, Marcos Augusto Silva

    2016-02-01

    Generation of electrical energy with renewable sources is interruptible due to the primary energy characteristics (sun, wind, hydro, etc.). In these cases, it is necessary to use energy storage so increasing penetrability of these sources connected to the distribution system. This paper discusses in details some equipment and accessories of an integrated power plant using fuel cell stack, electrolyzer and metal hydrides. During the plant operation were collected the power consumption data and established the efficiency of each plant component. These data demonstrated an overall efficiency of about 11% due to the low efficiencies of the commercial electrolyzers and power inverters used in the experiments.