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Sample records for catalytic transfer hydrogenation

  1. Skeletal Isomerization and Inter-molecular Hydrogen Transfer Reactions in Catalytic Cracking

    Institute of Scientific and Technical Information of China (English)

    Gao Yongcan; Zhang Jiushun; Xie Chaogang; Long Jun

    2002-01-01

    Bimolecular hydrogen transfer and skeletal isomerization are the important secondary reac tions among catalytic cracking reactions, which affect product yield distribution and product quality.Catalyst properties and operating parameters have great impact on bimolecular hydrogen transfer and skeletal isomerization reactions. Bimolecular hydrogen transfer activity and skeletal isomerization activity of USY-containing catalysts are higher than that of ZSM-5-containing catalyst. Coke deposition on the active sites of catalyst may suppress bimolecular hydrogen transfer activity and skeletal isomerization activity of catalyst in different degrees. Short reaction time causes a decrease of hydrogen trans fer reaction, but an increase of skeletal isomerization reaction compared to cracking reaction in catalytic cracking process.

  2. Iron Phthalocyanine as New Efficient Catalyst for Catalytic Transfer Hydrogenation of Simple Aldehydes and Ketones

    Czech Academy of Sciences Publication Activity Database

    Bata, P.; Notheisz, F.; Klusoň, Petr; Zsigmond, A.

    2015-01-01

    Roč. 29, JAN 2015 (2015), s. 45-49. ISSN 0268-2605 Institutional support: RVO:67985858 Keywords : heterogenized complexes * catalytic transfer hydrogenation * reusable catalyst Subject RIV: CC - Organic Chemistry Impact factor: 2.248, year: 2014

  3. Homogeneous Catalytic Transfer Hydrogenation in Microfluidic Flow System

    Czech Academy of Sciences Publication Activity Database

    Pavlorková, Jana; Křišťál, Jiří; Klusoň, Petr

    Budapest: Budapest University of Technology and Economics, 2014, s. 207-208. ISBN 978-963-05-9518-6. [International Conference on Microreactor Technology IMRET /13./. Budapest (HU), 23.06.2014-25.06.2014] Institutional support: RVO:67985858 Keywords : homogeneous catalysis * transfer hydrogenation * micro structured reactor systems Subject RIV: CI - Industrial Chemistry, Chemical Engineering

  4. Synthesis and Catalytic Hydrogen Transfer Reaction of Ruthenium(II) Complex

    Energy Technology Data Exchange (ETDEWEB)

    Son, Jung Ik; Kim, Aram; Noh, Hui Bog; Lee, Hyun Ju; Shim, Yoon Bo; Park, Kang Hyun [Pusan National University, Busan (Korea, Republic of)

    2012-01-15

    The ruthenium(II) complex [Ru(bpy){sub 2}-(PhenTPy)] was synthesized, and used for the transfer hydrogenation of ketones and the desired products were obtained in good yield. Based on the presented results, transition-metal complexes can be used as catalysts for a wide range of organic transformations. The relationship between the electro-reduction current density and temperature are being examined in this laboratory. Attempts to improve the catalytic activity and determine the transfer hydrogenation mechanism are currently in progress. The catalytic hydrogenation of a ketone is a basic and critical process for making many types of alcohols used as the final products and precursors in the pharmaceutical, agrochemical, flavor, fragrance, materials, and fine chemicals industries. The catalytic hydrogenation process developed by Noyori is a very attractive process. Formic acid and 2-propanol have been used extensively as hydrogenation sources. The advantage of using 2-propanol as a hydrogen source is that the only side product will be acetone, which can be removed easily during the workup process. Hydrogen transfer (HT) catalysis, which generates alcohols through the reduction of ketones, is an attractive protocol that is used widely. Ruthenium(II) complexes are the most useful catalysts for the hydrogen transfer (HT) of ketones. In this method, a highly active catalytic system employs a transition metal as a catalyst to synthesize alcohols, and is a replacement for the hydrogen-using hydrogenation process. The most active system is based on Ru, Rh and Ir, which includes a nitrogen ligand that facilitates the formation of a catalytically active hydride and phosphorus.

  5. Synthesis and Catalytic Hydrogen Transfer Reaction of Ruthenium(II) Complex

    International Nuclear Information System (INIS)

    The ruthenium(II) complex [Ru(bpy)2-(PhenTPy)] was synthesized, and used for the transfer hydrogenation of ketones and the desired products were obtained in good yield. Based on the presented results, transition-metal complexes can be used as catalysts for a wide range of organic transformations. The relationship between the electro-reduction current density and temperature are being examined in this laboratory. Attempts to improve the catalytic activity and determine the transfer hydrogenation mechanism are currently in progress. The catalytic hydrogenation of a ketone is a basic and critical process for making many types of alcohols used as the final products and precursors in the pharmaceutical, agrochemical, flavor, fragrance, materials, and fine chemicals industries. The catalytic hydrogenation process developed by Noyori is a very attractive process. Formic acid and 2-propanol have been used extensively as hydrogenation sources. The advantage of using 2-propanol as a hydrogen source is that the only side product will be acetone, which can be removed easily during the workup process. Hydrogen transfer (HT) catalysis, which generates alcohols through the reduction of ketones, is an attractive protocol that is used widely. Ruthenium(II) complexes are the most useful catalysts for the hydrogen transfer (HT) of ketones. In this method, a highly active catalytic system employs a transition metal as a catalyst to synthesize alcohols, and is a replacement for the hydrogen-using hydrogenation process. The most active system is based on Ru, Rh and Ir, which includes a nitrogen ligand that facilitates the formation of a catalytically active hydride and phosphorus

  6. Catalytic enantioselective OFF ↔ ON activation processes initiated by hydrogen transfer: concepts and challenges.

    Science.gov (United States)

    Quintard, Adrien; Rodriguez, Jean

    2016-08-18

    Hydrogen transfer initiated processes are eco-compatible transformations allowing the reversible OFF ↔ ON activation of otherwise unreactive substrates. The minimization of stoichiometric waste as well as the unique activation modes provided by these transformations make them key players for a greener future for organic synthesis. Long limited to catalytic reactions that form racemic products, considerable progress on the development of strategies for controlling diastereo- and enantioselectivity has been made in the last decade. The aim of this review is to present the different strategies that enable enantioselective transformations of this type and to highlight how they can be used to construct key synthetic building blocks in fewer operations with less waste generation. PMID:27381644

  7. Catalytic Transfer Hydrogenation of Furfural to Furfuryl Alcohol over Nitrogen-Doped Carbon-Supported Iron Catalysts.

    Science.gov (United States)

    Li, Jiang; Liu, Jun-Ling; Zhou, Hong-Jun; Fu, Yao

    2016-06-01

    Iron-based heterogeneous catalysts, which were generally prepared by pyrolysis of iron complexes on supports at elevated temperature, were found to be capable of catalyzing the transfer hydrogenation of furfural (FF) to furfuryl alcohol (FFA). The effects of metal precursor, nitrogen precursor, pyrolysis temperature, and support on catalytic performance were examined thoroughly, and a comprehensive study of the reaction parameters was also performed. The highest selectivity of FFA reached 83.0 % with a FF conversion of 91.6 % under the optimal reaction condition. Catalyst characterization suggested that iron cations coordinated by pyridinic nitrogen functionalities were responsible for the enhanced catalytic activity. The iron catalyst could be recycled without significant loss of catalytic activity for five runs, and the destruction of the nitrogen-iron species, the presence of crystallized Fe2 O3 phase, and the pore structure change were the main reasons for catalyst deactivation. PMID:27144965

  8. Effects of hydrophobic carrier and packing on the mass transfer capabilities in hydrogen-water liquid phase catalytic exchange bed

    International Nuclear Information System (INIS)

    Hydrogen-water liquid phase catalytic exchange bed was packed with 'sandwich' layers of the catalyst and the packing, and the effects of catalyst carrier, inert packing and their filled ratio on the overall mass transfer coefficient (Kya) were investigated experimentally. The results show that C-PTFE is suitable for hydrophobic catalyst. Kya of the bed with catalyst-stainless steel mini-spiral packing is better than that with stainless steel θ-packing, and the active Al2O3 is not suitable for the exchange bed. Moreover, if the stainless steel mini-spiral packing is etched in aqua regia, the operating flexibility and overall mass transfer capability of exchange bed are improved notably. The preferable packing ratio (catalyst/packing) is 1:4. (authors)

  9. Performance characterization of a hydrogen catalytic heater.

    Energy Technology Data Exchange (ETDEWEB)

    Johnson, Terry Alan; Kanouff, Michael P.

    2010-04-01

    This report describes the performance of a high efficiency, compact heater that uses the catalytic oxidation of hydrogen to provide heat to the GM Hydrogen Storage Demonstration System. The heater was designed to transfer up to 30 kW of heat from the catalytic reaction to a circulating heat transfer fluid. The fluid then transfers the heat to one or more of the four hydrogen storage modules that make up the Demonstration System to drive off the chemically bound hydrogen. The heater consists of three main parts: (1) the reactor, (2) the gas heat recuperator, and (3) oil and gas flow distribution manifolds. The reactor and recuperator are integrated, compact, finned-plate heat exchangers to maximize heat transfer efficiency and minimize mass and volume. Detailed, three-dimensional, multi-physics computational models were used to design and optimize the system. At full power the heater was able to catalytically combust a 10% hydrogen/air mixture flowing at over 80 cubic feet per minute and transfer 30 kW of heat to a 30 gallon per minute flow of oil over a temperature range from 100 C to 220 C. The total efficiency of the catalytic heater, defined as the heat transferred to the oil divided by the inlet hydrogen chemical energy, was characterized and methods for improvement were investigated.

  10. Field-controlled electron transfer and reaction kinetics of the biological catalytic system of microperoxidase-11 and hydrogen peroxide

    Directory of Open Access Journals (Sweden)

    Yongki Choi

    2011-12-01

    Full Text Available Controlled reaction kinetics of the bio-catalytic system of microperoxidase-11 and hydrogen peroxide has been achieved using an electrostatic technique. The technique allowed independent control of 1 the thermodynamics of the system using electrochemical setup and 2 the quantum mechanical tunneling at the interface between microperoxidase-11 and the working electrode by applying a gating voltage to the electrode. The cathodic currents of electrodes immobilized with microperoxidase-11 showed a dependence on the gating voltage in the presence of hydrogen peroxide, indicating a controllable reduction reaction. The measured kinetic parameters of the bio-catalytic reduction showed nonlinear dependences on the gating voltage as the result of modified interfacial electron tunnel due to the field induced at the microperoxidase-11-electrode interface. Our results indicate that the kinetics of the reduction of hydrogen peroxide can be controlled by a gating voltage and illustrate the operation of a field-effect bio-catalytic transistor, whose current-generating mechanism is the conversion of hydrogen peroxide to water with the current being controlled by the gating voltage.

  11. Field-controlled electron transfer and reaction kinetics of the biological catalytic system of microperoxidase-11 and hydrogen peroxide

    OpenAIRE

    Yongki Choi; Siu-Tung Yau

    2011-01-01

    Controlled reaction kinetics of the bio-catalytic system of microperoxidase-11 and hydrogen peroxide has been achieved using an electrostatic technique. The technique allowed independent control of 1) the thermodynamics of the system using electrochemical setup and 2) the quantum mechanical tunneling at the interface between microperoxidase-11 and the working electrode by applying a gating voltage to the electrode. The cathodic currents of electrodes immobilized with microperoxidase-11 showed...

  12. A General Catalytic Enantioselective Transfer Hydrogenation Reaction of β,β-Disubstituted Nitroalkenes Promoted by a Simple Organocatalyst.

    Science.gov (United States)

    Bernardi, Luca; Fochi, Mariafrancesca

    2016-01-01

    Given its synthetic relevance, the catalytic enantioselective reduction of β,β-disubstituted nitroalkenes has received a great deal of attention. Several bio-, metal-, and organo-catalytic methods have been developed, which however are usually applicable to single classes of nitroalkene substrates. In this paper, we present an account of our previous work on this transformation, which implemented with new disclosures and mechanistic insights results in a very general protocol for nitroalkene reductions. The proposed methodology is characterized by (i) a remarkably broad scope encompassing various nitroalkene classes; (ii) Hantzsch esters as convenient (on a preparative scale) hydrogen surrogates; (iii) a simple and commercially available thiourea as catalyst; (iv) user-friendly procedures. Overall, the proposed protocol gives a practical dimension to the catalytic enantioselective reduction of β,β-disubstituted nitroalkenes, offering a useful and general platform for the preparation of nitroalkanes bearing a stereogenic center at the β-position in a highly enantioenriched form. A transition state model derived from control kinetic experiments combined with literature data is proposed and discussed. This model accounts and justifies the observed experimental results. PMID:27483233

  13. Magnetic Co@g-C3N4 Core-Shells on rGO Sheets for Momentum Transfer with Catalytic Activity toward Continuous-Flow Hydrogen Generation.

    Science.gov (United States)

    Duan, Shasha; Han, Guosheng; Su, Yongheng; Zhang, Xiaoyu; Liu, Yanyan; Wu, Xianli; Li, Baojun

    2016-06-28

    Magnetic core-shell structures provide abundant opportunities for the construction of multifunctional composites. In this article, magnetic core-shells were fabricated with Co nanoparticles (NPs) as cores and g-C3N4 as shells. In the fabrication process, the Co@g-C3N4 core-shells were anchored onto the rGO nanosheets to form a Co@g-C3N4-rGO composite (CNG-I). For hydrogen generation from the hydrolysis of NaBH4 or NH3BH3, the Co NP cores act as catalytic active sites. The g-C3N4 shells protect Co NPs cores from aggregating or growing. The connection between Co NPs and rGO was strengthened by the g-C3N4 shells to prevent them from leaching or flowing away. The g-C3N4 shells also work as a cocatalyst for hydrogen generation. The magnetism of Co NPs and the shape of rGO nanosheets achieve effective momentum transfer in the external magnetic field. In the batch reactor, a higher catalytic activity was obtained for CNG-I in self-stirring mode than in magneton stirring mode. In the continuous-flow process, stable hydrogen generation was carried out with CNG-I being fixed and propelled by the external magnetic field. The separation film is unnecessary because of magnetic momentum transfer. This idea of the composite design and magnetic momentum transfer will be useful for the development of both hydrogen generation and multifunctional composite materials. PMID:27276187

  14. Catalytic Asymmetric Reduction of a 3,4-Dihydroisoquinoline for the Large-Scale Production of Almorexant: Hydrogenation or Transfer Hydrogenation?

    OpenAIRE

    Verzijl, Gerard K.M.; Vries, André H.M. de; Vries, Johannes G. de; Kapitan, Peter; Dax, Thomas; Helms, Matthias; Nazir, Zarghun; Skranc, Wolfgang; Imboden, Christoph; Stichler, Juergen; Ward, Richard A.; Abele, Stefan; Lefort, Laurent

    2013-01-01

    Several methods are presented for the enantioselective synthesis of the tetrahydroisoquinoline core of almorexant (ACT-078573A), a dual orexin receptor antagonist. Initial clinical supplies were secured by the Noyori Ru-catalyzed asymmetric transfer hydrogenation (Ru-Noyori ATH) of the dihydroisoquinoline precursor. Both the yield and enantioselectivity eroded upon scale-up. A broad screening exercise identified TaniaPhos as ligand for the iridium-catalyzed asymmetric hydrogenation with a ded...

  15. Catalytic Asymmetric Reduction of a 3,4-Dihydroisoquinoline for the Large-Scale Production of Almorexant : Hydrogenation or Transfer Hydrogenation?

    NARCIS (Netherlands)

    Verzijl, Gerard K.M.; Vries, André H.M. de; Vries, Johannes G. de; Kapitan, Peter; Dax, Thomas; Helms, Matthias; Nazir, Zarghun; Skranc, Wolfgang; Imboden, Christoph; Stichler, Juergen; Ward, Richard A.; Abele, Stefan; Lefort, Laurent

    2013-01-01

    Several methods are presented for the enantioselective synthesis of the tetrahydroisoquinoline core of almorexant (ACT-078573A), a dual orexin receptor antagonist. Initial clinical supplies were secured by the Noyori Ru-catalyzed asymmetric transfer hydrogenation (Ru-Noyori ATH) of the dihydroisoqui

  16. Catalytic hydrogenation of carbon monoxide

    International Nuclear Information System (INIS)

    Focus of this project is on developing new approaches for hydrogenation of carbon monoxide to produce organic oxygenates at mild conditions. The strategies to accomplish CO reduction are based on favorable thermodynamics manifested by rhodium macrocycles for producing a series of intermediates implicated in the catalytic hydrogenation of CO. Metalloformyl complexes from reactions of H2 and CO, and CO reductive coupling to form metallo α-diketone species provide alternate routes to organic oxygenates that utilize these species as intermediates. Thermodynamic and kinetic-mechanistic studies are used in guiding the design of new metallospecies to improve the thermodynamic and kinetic factors for individual steps in the overall process. Electronic and steric effects associated with the ligand arrays along with the influences of the reaction medium provide the chemical tools for tuning these factors. Non-macrocyclic ligand complexes that emulate the favorable thermodynamic features associated with rhodium macrocycles, but that also manifest improved reaction kinetics are promising candidates for future development

  17. A novel liquid system of catalytic hydrogenation

    Institute of Scientific and Technical Information of China (English)

    LI; XiaoNian; XIANG; YiZhi

    2007-01-01

    On the basis that endothermic aqueous-phase reforming of oxygenated hydrocarbons for H2 production and exothermic liquid phase hydrogenation of organic compounds are carried out under extremely close conditions of temperature and pressure over the same type of catalyst, a novel liquid system of catalytic hydrogenation has been proposed, in which hydrogen produced from aqueous-phase reforming of oxygenated hydrocarbons is in situ used for liquid phase hydrogenation of organic compounds. The usage of active hydrogen generated from aqueous-phase reforming of oxygenated hydrocarbons for liquid catalytic hydrogenation of organic compounds could lead to increasing the selectivity to H2 in the aqueous-phase reforming due to the prompt removal of hydrogen on the active centers of the catalyst. Meanwhile, this novel liquid system of catalytic hydrogenation might be a potential method to improve the selectivity to the desired product in liquid phase catalytic hydrogenation of organic compounds. On the other hand, for this novel liquid system of catalytic hydrogenation, some special facilities for H2 generation, storage and transportation in traditional liquid phase hydrogenation industry process are yet not needed. Thus, it would simplify the working process of liquid phase hydrogenation and increase the energy usage and hydrogen productivity.

  18. Activation of the C-H bond: catalytic hydroxylation of hydrocarbons by new cobaltic alkylperoxydic complexes; selective and catalytic cycloalkane dehydrogenation in presence of uranium for hydrogen transfer

    International Nuclear Information System (INIS)

    The aim of the thesis is to improve efficiency and selectivity of chemical reactions for alkane transformations. In the first part decomposition of hydroperoxides and hydrocarbon hydroxylation by cobalt complexes is studied. In the second part cycloalkanes are dehydrogenated into aromatics with a Pt catalyst, trapping hydrogen by uranium. Uranium hydride UH3 can yield very pure hydrogen at reasonable temperature

  19. Catalytic transfer hydrogenation for stabilization of bio-oil oxygenates: reduction of p-cresol and furfural over bimetallic Ni-Cu catalysts using isopropanol

    Science.gov (United States)

    Transfer hydrogenation and hydrodeoxygenation of model bio-oil compounds (p-cresol and furfural) and bio-oils derived from biomass via traditional pyrolysis and tail-gas reactive pyrolysis (TGRP) were conducted. Mild batch reaction conditions were employed, using isopropanol as a hydrogen donor over...

  20. Polarographic catalytic wave of hydrogen--Parallel catalytic hydrogen wave of bovine serum albumin in thepresence of oxidants

    Institute of Scientific and Technical Information of China (English)

    过玮; 刘利民; 林洪; 宋俊峰

    2002-01-01

    A polarographic catalytic hydrogen wave of bovine serum albumin (BSA) at about -1.80 V (vs. SCE) in NH4Cl-NH3@H2O buffer is further catalyzed by such oxidants as iodate, persulfate and hydrogen peroxide, producing a kinetic wave. Studies show that the kinetic wave is a parallel catalytic wave of hydrogen, which resulted from that hydrogen ion is electrochemically reduced and chemically regenerated through oxidation of its reduction product, atomic hydrogen, by oxidants mentioned above. It is a new type of poralographic catalytic wave of protein, which is suggested to be named as a parallel catalytic hydrogen wave.

  1. Catalytic hydrogen recombination for nuclear containments

    International Nuclear Information System (INIS)

    Catalytic recombiners appear to be a credible option for hydrogen mitigation in nuclear containments. The passive operation, versatility and ease of back fitting are appealing for existing stations and new designs. Recently, a generation of wet-proofed catalyst materials have been developed at AECL which are highly specific to H2-O2, are active at ambient temperatures and are being evaluated for containment applications. Two types of catalytic recombiners were evaluated for hydrogen removal in containments based on the AECL catalyst. The first is a catalytic combustor for application in existing air streams such as provided by fans or ventilation systems. The second is an autocatalytic recombiner which uses the enthalpy of reaction to produce natural convective flow over the catalyst elements. Intermediate-scale results obtained in 6 m3 and 10 m3 spherical and cylindrical vessels are given to demonstrate self-starting limits, operating limits, removal capacity, scaling parameters, flow resistance, mixing behaviour in the vicinity of an operating recombiner and sensitivity to poisoning, fouling and radiation. (author). 13 refs., 10 figs

  2. Catalytic transfer hydrogenation of azobenzene by low-valent nickel complexes: a route to 1,2-disubstituted benzimidazoles and 2,4,5-trisubstituted imidazolines.

    Science.gov (United States)

    Zurita, Daniel A; Flores-Alamo, Marcos; García, Juventino J

    2016-06-21

    The one-pot synthesis of 1,2-disubstituted benzimidazoles by the transfer hydrogenation of azobenzene, using benzylamine as a hydrogen donor, sequential rearrangement of hydrazobenzene to semidine and further condensation with N-benzylideneamine is reported, catalyzed by 2 mol% of [Ni(COD)2] : dippe. The N2 substitution on benzimidazole can be controlled by the selection of different azobenzenes and C2 substitution will only depend on the chosen benzylamine. The current methodology avoids the addition of external oxidants, which are needed in the classical benzimidazole synthesis. In addition, the byproduct, N-benzylideneamine, obtained from dehydrogenation of benzylamine produced 2,4,5-trisubstituted imidazolines by cyclization and C-H functionalization, and this route was optimized with the use of 2 mol% of [Ni(COD)2] : 2PPh3. PMID:27254530

  3. Catalytic glycerol steam reforming for hydrogen production

    International Nuclear Information System (INIS)

    Hydrogen production from glycerol by steam reforming combine two major advantages: (i) using glycerol as raw material add value to this by product of bio-diesel production which is obtained in large quantities around the world and have a very limited utilization now, and (ii) by implication of water molecules in the reaction the efficiency of hydrogen generation is increased as each mol of glycerol produces 7 mol of H2. In this work we present the results obtained in the process of steam reforming of glycerol on Ni/Al2O3. The catalyst was prepared by wet impregnation method and characterized through different methods: N2 adsorption-desorption, XRD, TPR. The catalytic study was performed in a stainless steel tubular reactor at atmospheric pressure by varying the reaction conditions: steam/carbon ratio (1-9), gas flow (35 ml/min -133 ml/min), temperature (450-650°C). The gaseous fraction of the reaction products contain: H2, CH4, CO, CO2. The optimum reaction conditions as resulted from this study are: temperature 550°C, Gly:H2O ratio 9:1 and Ar flow 133 ml/min. In these conditions the glycerol conversion to gaseous products was 43% and the hydrogen yield was 30%

  4. Catalytic glycerol steam reforming for hydrogen production

    Energy Technology Data Exchange (ETDEWEB)

    Dan, Monica, E-mail: monica.dan@itim-cj.ro; Mihet, Maria, E-mail: maria.mihet@itim-cj.ro; Lazar, Mihaela D., E-mail: diana.lazar@itim-cj.ro [National Institute for Research and Development of Isotopic and Molecular Technologies, 67-103 Donat Street, 400293 Cluj Napoca (Romania)

    2015-12-23

    Hydrogen production from glycerol by steam reforming combine two major advantages: (i) using glycerol as raw material add value to this by product of bio-diesel production which is obtained in large quantities around the world and have a very limited utilization now, and (ii) by implication of water molecules in the reaction the efficiency of hydrogen generation is increased as each mol of glycerol produces 7 mol of H{sub 2}. In this work we present the results obtained in the process of steam reforming of glycerol on Ni/Al{sub 2}O{sub 3}. The catalyst was prepared by wet impregnation method and characterized through different methods: N{sub 2} adsorption-desorption, XRD, TPR. The catalytic study was performed in a stainless steel tubular reactor at atmospheric pressure by varying the reaction conditions: steam/carbon ratio (1-9), gas flow (35 ml/min -133 ml/min), temperature (450-650°C). The gaseous fraction of the reaction products contain: H{sub 2}, CH{sub 4}, CO, CO{sub 2}. The optimum reaction conditions as resulted from this study are: temperature 550°C, Gly:H{sub 2}O ratio 9:1 and Ar flow 133 ml/min. In these conditions the glycerol conversion to gaseous products was 43% and the hydrogen yield was 30%.

  5. Catalytic glycerol steam reforming for hydrogen production

    Science.gov (United States)

    Dan, Monica; Mihet, Maria; Lazar, Mihaela D.

    2015-12-01

    Hydrogen production from glycerol by steam reforming combine two major advantages: (i) using glycerol as raw material add value to this by product of bio-diesel production which is obtained in large quantities around the world and have a very limited utilization now, and (ii) by implication of water molecules in the reaction the efficiency of hydrogen generation is increased as each mol of glycerol produces 7 mol of H2. In this work we present the results obtained in the process of steam reforming of glycerol on Ni/Al2O3. The catalyst was prepared by wet impregnation method and characterized through different methods: N2 adsorption-desorption, XRD, TPR. The catalytic study was performed in a stainless steel tubular reactor at atmospheric pressure by varying the reaction conditions: steam/carbon ratio (1-9), gas flow (35 ml/min -133 ml/min), temperature (450-650°C). The gaseous fraction of the reaction products contain: H2, CH4, CO, CO2. The optimum reaction conditions as resulted from this study are: temperature 550°C, Gly:H2O ratio 9:1 and Ar flow 133 ml/min. In these conditions the glycerol conversion to gaseous products was 43% and the hydrogen yield was 30%.

  6. Microchannel Reactor System for Catalytic Hydrogenation

    Energy Technology Data Exchange (ETDEWEB)

    Adeniyi Lawal; Woo Lee; Ron Besser; Donald Kientzler; Luke Achenie

    2010-12-22

    We successfully demonstrated a novel process intensification concept enabled by the development of microchannel reactors, for energy efficient catalytic hydrogenation reactions at moderate temperature, and pressure, and low solvent levels. We designed, fabricated, evaluated, and optimized a laboratory-scale microchannel reactor system for hydrogenation of onitroanisole and a proprietary BMS molecule. In the second phase of the program, as a prelude to full-scale commercialization, we designed and developed a fully-automated skid-mounted multichannel microreactor pilot plant system for multiphase reactions. The system is capable of processing 1 – 10 kg/h of liquid substrate, and an industrially relevant immiscible liquid-liquid was successfully demonstrated on the system. Our microreactor-based pilot plant is one-of-akind. We anticipate that this process intensification concept, if successfully demonstrated, will provide a paradigm-changing basis for replacing existing energy inefficient, cost ineffective, environmentally detrimental slurry semi-batch reactor-based manufacturing practiced in the pharmaceutical and fine chemicals industries.

  7. Numerical Study of Passive Catalytic Recombiner for Hydrogen Mitigation

    Directory of Open Access Journals (Sweden)

    Pavan K Sharma

    2010-10-01

    Full Text Available A significant amount of hydrogen is expected to be released within the containment of a water cooled power reactor after a severe accident. To reduce the risk of deflagration/detonation various means for hydrogen control have been adopted all over the world. Passive catalytic recombiner with vertical flat catalytic plate is one of such hydrogen mitigating device. Passive catalytic recombiners are designed for the removal of hydrogen generated in order to limit the impact of possible hydrogen combustion. Inside a passive catalytic recombiner, numerous thin steel sheets coated with catalyst material are vertically arranged at the bottom opening of a sheet metal housing forming parallel flow channels for the surrounding gas atmosphere. Already below conventional flammability limits, hydrogen and oxygen react exothermally on the catalytic surfaces forming harmless steam. Detailed numerical simulations and experiments are required for an in-depth knowledge of such plate type catalytic recombiners. Specific finite volume based in-house CFD code has been developed to model and analyse the working of these recombiner. The code has been used to simulate the recombiner device used in the Gx-test series of Battelle-Model Containment (B-MC experiments. The present paper briefly describes the working principle of such passive catalytic recombiner and salient feature of the CFD model developed at Bhabha Atomic Research Centre (BARC. Finally results of the calculations and comparison with existing data are discussed.

  8. Catalytic Transfer Hydogenation Reactions for Undergraduate Practical Programs

    Science.gov (United States)

    Hanson, R. W.

    1997-04-01

    A brief review of catalytic transfer hydrogenation (CTH) reactions is given. Attention is drawn, particularly, to the utility of ammonium formate as the hydrogen donor in this type of reaction. The reduction of aryl carbonyl compounds to the corresponding methylene derivatives by ammonium formate in the presence of 10% Pd/C at 110°C is compared to their reductive ammonation which occurs at higher temperatures in the absence of the catalyst (the Leuckart reaction). It is suggested that the low cost and simplicity of CTH reactions using ammonium formate as the hydrogen donor, together with the high yields obtained in many cases, make them excellent candidates for inclusion in undergraduate practical programmes. Laboratory instructions are given for the reduction of nitrobenzene to aniline (isolated as benzanilide), benzophenone to diphenylmethanol and fluorenone to fluorene, in all cases using ammonium formate as the hydrogen donor and 10% Pd/C as the catalyst. Thin layer chromatography shows that in each case the product is homogeneous; the yields are essentially quantitative.

  9. Homogeneous catalytic hydrogenations of complex carbonaceous substrates. [16 references

    Energy Technology Data Exchange (ETDEWEB)

    Cox, J L; Wilcox, W A; Roberts, G L

    1976-11-05

    Results of homogeneous catalytic hydrogenation of complex unsaturated substrates including coal and coal-derived materials are reported, with organic soluble molecular complexes as catalysts. Among the substrates used were Hvab coal, solvent-refined coal, and COED pyrolysate. The hydrogenations were carried out in an autoclave. The results are summarized in tables.

  10. Hydrogen-Atom Transfer Reactions.

    Science.gov (United States)

    Wang, Liang; Xiao, Jian

    2016-04-01

    The cascade [1,n]-hydrogen transfer/cyclization, recognized as the tert-amino effect one century ago, has received considerable interest in recent decades, and great achievements have been made. With the aid of this strategy, the inert C(sp(3))-H bonds can be directly functionalized into C-C, C-N, C-O bonds under catalysis of Lewis acids, Brønsted acids, as well as organocatalysts, and even merely under thermal conditions. Hydrogen can be transferred intramolecularly from hydrogen donor to acceptor in the form of hydride, or proton, followed by cyclization to furnish the cyclic products in processes featuring high atom economy. Methylene/methine adjacent to heteroatoms, e.g., nitrogen, oxygen, sulfur, can be exploited as hydride donor as well as methylene/methine without heteroatom assistance. Miscellaneous electrophilic subunits or intermediates, e.g., alkylidene malonate, carbophilic metal activated alkyne or allene, α,β-unsaturated aldehydes/ketone, saturated aldehydes/iminium, ketenimine/carbodiimide, metal carbenoid, electron-withdrawing groups activated allene/alkyne, in situ generated carbocation, can serve as hydride acceptors. This methodology has shown preeminent power to construct 5-, 6-, or 7-membered heterocyclic as well as carbon rings. In this chapter, various hydrogen donors and acceptors are adequately discussed. PMID:27573142

  11. Hydrophilic pyrazine-based phosphane ligands: synthesis and application in asymmetric hydride transfer and H2-hydrogenation of acetophenone

    NARCIS (Netherlands)

    Nikishkin, N.; Huskens, J.; Verboom, W.

    2013-01-01

    Pyrazine-based hydrophilic phosphanes are useful ligands for the ruthenium- and rhodium-catalyzed hydrogenations of acetophenone under hydride transfer and dihydrogen conditions. The effect of alcohol additives on the catalytic, enantioselective aqueous hydrogenation of acetophenone is examined with

  12. Short hydrogen bonds in the catalytic mechanism of serine proteases

    Directory of Open Access Journals (Sweden)

    VLADIMIR LESKOVAC

    2008-04-01

    Full Text Available The survey of crystallographic data from the Protein Data Bank for 37 structures of trypsin and other serine proteases at a resolution of 0.78–1.28 Å revealed the presence of hydrogen bonds in the active site of the enzymes, which are formed between the catalytic histidine and aspartate residues and are on average 2.7 Å long. This is the typical bond length for normal hydrogen bonds. The geometric properties of the hydrogen bonds in the active site indicate that the H atom is not centered between the heteroatoms of the catalytic histidine and aspartate residues in the active site. Taken together, these findings exclude the possibility that short “low-barrier” hydrogen bonds are formed in the ground state structure of the active sites examined in this work. Some time ago, it was suggested by Cleland that the “low-barrier hydrogen bond” hypothesis is operative in the catalytic mechanism of serine proteases, and requires the presence of short hydrogen bonds around 2.4 Å long in the active site, with the H atom centered between the catalytic heteroatoms. The conclusions drawn from this work do not exclude the validity of the “low-barrier hydrogen bond” hypothesis at all, but they merely do not support it in this particular case, with this particular class of enzymes.

  13. Catalytic Processes for Clean Hydrogen Production from Hydrocarbons

    OpenAIRE

    ÖNSAN, Zeynep İlsen

    2007-01-01

    Conversion of hydrocarbon fuels to hydrogen with a high degree of purity acceptable for fuel cell operation presents interesting challenges for the design of new selective catalysts and catalytic processes. Natural gas, LPG, gasoline, and diesel are regarded as promising hydrocarbon fuels. Methanol has received attention despite its toxicity, and ethanol has recently become of interest as a much less toxic and renewable resource. Selective catalytic processes considered for commerci...

  14. Theoretical studies of the proton transfer behaviors in molecular complexes analogous to catalytic triad of serine protease: Toward understanding the existence and significance of the low-barrier hydrogen-bond in enzymatic catalysis

    Institute of Scientific and Technical Information of China (English)

    LI Ping; WANG WeiHua; BI SiWei; SONG Rui; BU YuXiang

    2009-01-01

    A representative acetate-(5-methylimidazole)-methanol system has been employed as a model of cata-lytic triad in serine protease to validate the formation processes of low-barrier H-bonds (LBHB) at the B3LYP/6-311++G** level of theory, and variable H-bonding characters from conventional ones to LBHBs have been represented along with the proceedings of proton transfer. Solvent effect is an important factor in modulation of the existence of an LBHB, where an LBHB (or a conventional H-bond) in the gas phase can be changed into a non-LBHB (an LBHB) upon solvation. The origin of the additional stabili-zation energy arising from the LBHB may be attributed to the H-bonding energy difference before and after proton transfer because the shared proton can freely move between the proton donor and proton acceptor. Most importantly, the order of magnitude of the stabilization energy depends on the studied systems. Furthermore, the nonexistence of LBHBs in the catalytic triad of serine proteases has been verified in a more sophisticated model treated using the ONIOM method. As a result, only the single proton transfer mechanism in the catalytic triad has been confirmed and the origin of the powerful catalytic efficiency of serine proteases should be attributed to other factors rather than the LBHB.

  15. Theoretical studies of the proton transfer behaviors in molecular complexes analogous to catalytic triad of serine protease:Toward understanding the existence and significance of the low-barrier hydrogen-bond in enzymatic catalysis

    Institute of Scientific and Technical Information of China (English)

    2009-01-01

    A representative acetate-(5-methylimidazole)-methanol system has been employed as a model of catalytic triad in serine protease to validate the formation processes of lowbarrier H-bonds(LBHB) at the B3LYP/6-311++G level of theory,and variable H-bonding characters from conventional ones to LBHBs have been represented along with the proceedings of proton transfer.Solvent effect is an important factor in modulation of the existence of an LBHB,where an LBHB(or a conventional H-bond) in the gas phase can be changed into a non-LBHB(an LBHB) upon solvation.The origin of the additional stabili-zation energy arising from the LBHB may be attributed to the H-bonding energy difference before and after proton transfer because the shared proton can freely move between the proton donor and proton acceptor.Most importantly,the order of magnitude of the stabilization energy depends on the studied systems.Furthermore,the nonexistence of LBHBs in the catalytic triad of serine proteases has been verified in a more sophisticated model treated using the ONIOM method.As a result,only the single proton transfer mechanism in the catalytic triad has been confirmed and the origin of the powerful catalytic efficiency of serine proteases should be attributed to other factors rather than the LBHB.

  16. Qualification of a passive catalytic module for hydrogen mitigation

    International Nuclear Information System (INIS)

    The advantage of passive catalytic modules for hydrogen mitigation during core-melt accidents, as compared with active devices like forced-flow recombiners or ignitors, is given by the high reliability of operation and the elimination of potentially violent combustion events. An important step in the qualification of a passive catalytic module system is the determination of the total required capacity and its distribution at various locations in the containment. Experiments and analytic modeling work were performed to qualify the installation of a system of catalytic modules for a large dry pressurized water reactor (PWR) containment. The operational capacity of a prototype catalytic module was determined experimentally, and a corresponding model correlation was developed and integrated into the GOTHIC containment code. This modified code was validated against experimental data. As an application, predictions of the effects, resulting from backfitting a large, dry PWR containment with 50 catalytic modules, were done using the modified code. The catalytic modules keep the hydrogen concentrations below a level of 10% where violent deflagrations could be expected. Local higher concentrations near the release location are inert due to associated low oxygen and high steam concentrations. A proper distribution of the modules in the containment guarantees full mixing of the atmosphere due to natural convective currents

  17. Review of literature on catalytic recombination of hydrogen--oxygen

    International Nuclear Information System (INIS)

    The results are reported of a literature search for information concerning the heterogeneous, gas phase, catalytic hydrogen-oxygen recombination. Laboratory scale experiments to test the performance of specific metal oxide catalysts under conditions simulating the atmosphere within a nuclear reactor containment vessel following a loss-of-coolant blowdown accident are suggested

  18. Catalytic Hydrogenation Reaction of Naringin-Chalcone. Study of the Electrochemical Reaction

    OpenAIRE

    B. A. López de Mishima; H. T. Mishima; A. N. Giannuzzo; M. A. Nazareno

    2000-01-01

    The electrocatalytic hydrogenation reaction of naringin derivated chalcone is studied. The reaction is carried out with different catalysts in order to compare with the classic catalytic hydrogenation.

  19. Catalytic hydrogen evolution by polyaminoacids using mercury electrode

    Directory of Open Access Journals (Sweden)

    Marko Živanovič

    2010-12-01

    Full Text Available It was shown that using constant current chronopotentiometricstripping (CPS peptides and proteins at nanomolar concentrations produce protein structure–sensitive peak H at mercury electrodes. This peak is due to the catalytic hydrogen evolution reaction (HER. Polyamino acids can be considered as an intermediate model system between peptides and macromolecular proteins. Here we used polyamino acids (poly(aa such as polylysine (polyLys and polyarginine (polyArg and cyclic voltammetry or CPS in combination with hanging mercury drop electrode to explore how different amino acid residues in proteins contribute to the catalyticHER.

  20. Radiation-induced hydrogen transfer in metals

    Science.gov (United States)

    Tyurin, Yu I.; Vlasov, V. A.; Dolgov, A. S.

    2015-11-01

    The paper presents processes of hydrogen (deuterium) diffusion and release from hydrogen-saturated condensed matters in atomic, molecular and ionized states under the influence of the electron beam and X-ray radiation in the pre-threshold region. The dependence is described between the hydrogen isotope release intensity and the current density and the electron beam energy affecting sample, hydrogen concentration in the material volume and time of radiation exposure to the sample. The energy distribution of the emitted positive ions of hydrogen isotopes is investigated herein. Mechanisms of radiation-induced hydrogen transfer in condensed matters are suggested.

  1. CATALYTIC HYDROGENATION AND OXIDATION OF BIOMASS-DERIVED LEVULINIC ACID

    OpenAIRE

    Yan Gong; Lu Lin; Zhipei Yan

    2011-01-01

    Levulinic acid (LA), 4-oxo-pentanoic acid, is a new platform chemical with various potential uses. In this paper, catalytic hydrogenation and oxidation of levulinic acid were studied. It was shown from experiments that levulinic acid can be hydrogenated to γ-valerolactone (GVL) over transition metal catalysts and oxidative-decarboxylated to 2-butanone (methyl-ethyl-ketone, MEK) and methyl-vinyl-ketone (MVK) by cupric oxide (CuO), cupric oxide/cerium oxide (CuO/CeO2), cupric oxide/ alumina (Cu...

  2. CATALYTIC HYDROGENATION AND OXIDATION OF BIOMASS-DERIVED LEVULINIC ACID

    Directory of Open Access Journals (Sweden)

    Yan Gong

    2011-02-01

    Full Text Available Levulinic acid (LA, 4-oxo-pentanoic acid, is a new platform chemical with various potential uses. In this paper, catalytic hydrogenation and oxidation of levulinic acid were studied. It was shown from experiments that levulinic acid can be hydrogenated to γ-valerolactone (GVL over transition metal catalysts and oxidative-decarboxylated to 2-butanone (methyl-ethyl-ketone, MEK and methyl-vinyl-ketone (MVK by cupric oxide (CuO, cupric oxide/cerium oxide (CuO/CeO2, cupric oxide/ alumina (CuO/ Al2O3, and silver(I/ peroxydisulfate (Ag(I/S2O82-.

  3. Hydrogen mitigation by catalytic recombiners and ignition during severe accidents

    International Nuclear Information System (INIS)

    A large amount of hydrogen is expected to be released within a large dry containment of a PWR shortly after the onset of a severe accident, leading to core melting. According to local gas concentrations, turbulence and structural configurations within the containment, the released hydrogen can reach the boundary of deflagration or under certain conditions cause local detonations threatening the containment integrity. During the last few years, several concepts of mitigation have been developed to limit the hydrogen concentrations and extensive efforts have been given to investigate the use of catalytic recombiners as well as the use of deliberate ignition within the contemplated framework of a 'Dual-concept'. Although the recent recommendation of the German Reactor Safety Commission (RSK) foresees the sole application of catalytic recombiners to remove hydrogen during severe accident, a review is planned within two years for the partial and directed additional application of early ignitions or post dilution of the atmosphere of the compartments in conjunction with the recombiners installed. This presentation will review the results of large number of experiments performed both in small scale and large scale to qualify the recombiners. It is also the subject of the presentation to address the requirements for proper and secure functioning of the catalyzers under the existing boundary conditions during the severe accidents. These requirements ask for measures, starting from the proper selection of catalysts, multi purposed catalytic devices and their protection against contamination during the standby condition as well as against aerosol deposition and surface poisoning during the propagation of an accident. A short review of the results to large scale experiments with the combined application of catalytic devices and igniters form also a part of this presentation. (author). 8 refs., 2 tabs., 7 figs

  4. Catalytic hydrogenation reactors for the fine chemicals industries. Their design and operation.

    OpenAIRE

    Westerterp, K.R.; Molga, E.J.; Gelder, van, M.

    1997-01-01

    The design and operation of reactors for catalytic, hydrogenation in the fine chemical industries are discussed. The requirements for a good multiproduct catalytic hydrogenation unit as well as the choice of the reactor type are considered. Packed bed bubble column reactors operated without hydrogen recycle are recommended as the best choice to obtain a flexible reactor with good selectivities. The results of an experimental study of the catalytic hydrogenation of 2,4-dinitrotoluene in a mini...

  5. 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

  6. 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

  7. Simple and rapid hydrogenation of p-nitrophenol with aqueous formic acid in catalytic flow reactors

    Directory of Open Access Journals (Sweden)

    Rahat Javaid

    2013-06-01

    Full Text Available The inner surface of a metallic tube (i.d. 0.5 mm was coated with a palladium (Pd-based thin metallic layer by flow electroless plating. Simultaneous plating of Pd and silver (Ag from their electroless-plating solution produced a mixed distributed bimetallic layer. Preferential acid leaching of Ag from the Pd–Ag layer produced a porous Pd surface. Hydrogenation of p-nitrophenol was examined in the presence of formic acid simply by passing the reaction solution through the catalytic tubular reactors. p-Aminophenol was the sole product of hydrogenation. No side reaction occurred. Reaction conversion with respect to p-nitrophenol was dependent on the catalyst layer type, the temperature, pH, amount of formic acid, and the residence time. A porous and oxidized Pd (PdO surface gave the best reaction conversion among the catalytic reactors examined. p-Nitrophenol was converted quantitatively to p-aminophenol within 15 s of residence time in the porous PdO reactor at 40 °C. Evolution of carbon dioxide (CO2 was observed during the reaction, although hydrogen (H2 was not found in the gas phase. Dehydrogenation of formic acid did not occur to any practical degree in the absence of p-nitrophenol. Consequently, the nitro group was reduced via hydrogen transfer from formic acid to p-nitrophenol and not by hydrogen generated by dehydrogenation of formic acid.

  8. Simple and rapid hydrogenation of p-nitrophenol with aqueous formic acid in catalytic flow reactors.

    Science.gov (United States)

    Javaid, Rahat; Kawasaki, Shin-Ichiro; Suzuki, Akira; Suzuki, Toshishige M

    2013-01-01

    The inner surface of a metallic tube (i.d. 0.5 mm) was coated with a palladium (Pd)-based thin metallic layer by flow electroless plating. Simultaneous plating of Pd and silver (Ag) from their electroless-plating solution produced a mixed distributed bimetallic layer. Preferential acid leaching of Ag from the Pd-Ag layer produced a porous Pd surface. Hydrogenation of p-nitrophenol was examined in the presence of formic acid simply by passing the reaction solution through the catalytic tubular reactors. p-Aminophenol was the sole product of hydrogenation. No side reaction occurred. Reaction conversion with respect to p-nitrophenol was dependent on the catalyst layer type, the temperature, pH, amount of formic acid, and the residence time. A porous and oxidized Pd (PdO) surface gave the best reaction conversion among the catalytic reactors examined. p-Nitrophenol was converted quantitatively to p-aminophenol within 15 s of residence time in the porous PdO reactor at 40 °C. Evolution of carbon dioxide (CO2) was observed during the reaction, although hydrogen (H2) was not found in the gas phase. Dehydrogenation of formic acid did not occur to any practical degree in the absence of p-nitrophenol. Consequently, the nitro group was reduced via hydrogen transfer from formic acid to p-nitrophenol and not by hydrogen generated by dehydrogenation of formic acid. PMID:23843908

  9. Selective Hydrogen Transfer Reaction in FCC Process:Characterization and Application

    Institute of Scientific and Technical Information of China (English)

    Chen Beiyan; He Mingyuan; Da Zhijian

    2003-01-01

    The product distribution and gasoline quality of FCC process, especially the olefin content,heavily depends on the catalyst performance in terms of selective/non-selective hydrogen transfer reaction selectivity. A reliable experimental protocol has been established by using n-dodecane as a probe molecule to characterize the selective hydrogen transfer ability of catalytic materials. The results obtained have been correlated with the performance of the practical catalysts.

  10. Voltammetric determination of ruthenium and rhodium from catalytic hydrogen currents

    International Nuclear Information System (INIS)

    Electroreduction of Ru(3) and Rh(3) complexes with diethyldithiocarbaminate (DEDTC), ethylxanthate (EX) and diethyldithiophosphate (DEDTP) on mercury dropping electrode was studied to choose ligand in catalytically active complex, providing small value of the low limit of determined contents. Reduction was conducted in DMFA mixture with universal buffer solution (1:1). The value of catalytical current of hydrogen, evolved on the electrode, decreased in DEDTC>EX>DEDTP series. DEDTC application enables to determine Rh and Ru during simultaneous presence in 1:10 ratio without separation of base elements (Pt, Pd, Ir, Au) with low limit of determination 2 X 10-8 MRh and 8 X 10-8MRu in copper-nickel sulfide ores. Preliminary extraction of Ru and Rh diethyldithiocarbamates into dichloroethane was used for decreasing the detection limit; this provides 20-fold concentration of elements

  11. Three Phase Catalytic Hydrogenation in Falling Film Microreactor

    Czech Academy of Sciences Publication Activity Database

    Stavárek, Petr; de Bellefon, C.

    Praha : Process Engineering Publisher, 2010, s. 289. ISBN 978-80-02-02246-6. [International Congress of Chemical and Process Engineering CHISA 2010 /19./ - European Congress of Chemical Engineering ECCE-7 /7./. Prague (CZ), 28.08.2010-01.09.2010] Grant ostatní: IMPULSE(XE) NMP2/CT/2005/011816 Institutional research plan: CEZ:AV0Z40720504 Keywords : falling film * microreactor * catalytic hydrogenation Subject RIV: CI - Industrial Chemistry, Chemical Engineering www.chisa.cz/2010, www.ecce7.com

  12. Catalytic hydrogenation of uranyl nitrate - engineering scale studies

    International Nuclear Information System (INIS)

    Uranous nitrate is employed as partitioning agent for the separation of plutonium from uranium in PUREX process, the conventional process for the reprocessing of spent nuclear fuel. It is currently produced from uranyl nitrate solution by the electrochemical route. Since the conversion is only 50%, an innovative method based on catalytic hydrogenation has been developed. Parametric studies have been carried out on 5 L scale using natural uranyl nitrate solution as fed. Based on these studies, number of runs were carried out on engineering scale using contaminated uranyl nitrate solution. More than 100 kg of uranous nitrate has been made. Performance of the reduction process is described in detail. (author)

  13. Catalytic Hydrogenation Reaction of Naringin-Chalcone. Study of the Electrochemical Reaction

    Directory of Open Access Journals (Sweden)

    B. A. López de Mishima

    2000-03-01

    Full Text Available The electrocatalytic hydrogenation reaction of naringin derivated chalcone is studied. The reaction is carried out with different catalysts in order to compare with the classic catalytic hydrogenation.

  14. CATALYTIC HYDROGENATION OF ACRYLATE ASMMETRIC Dd(Ⅱ)—CHELATING RESINS CONTAINING AMINO ACID LIGANDS

    Institute of Scientific and Technical Information of China (English)

    Wangying; WangHongzuo; 等

    1995-01-01

    The catalytic hydrogenation of palladium chelating resins containing chiral amino acid ligands based on lower crosslinked poly(chloroethyl acrylate) and some effects on the rate of hydrogenation were studied.

  15. Size-Dependent Catalytic Activity of Palladium Nanoparticles Fabricated in Porous Organic Polymers for Alkene Hydrogenation at Room Temperature.

    Science.gov (United States)

    Mondal, John; Trinh, Quang Thang; Jana, Avijit; Ng, Wilson Kwok Hung; Borah, Parijat; Hirao, Hajime; Zhao, Yanli

    2016-06-22

    Ultrafine palladium nanoparticles (Pd NPs) with 8 and 3 nm sizes were effectively fabricated in triazine functionalized porous organic polymer (POP) TRIA that was developed by nonaqueous polymerization of 2,4,6-triallyoxy-1,3,5-triazine. The Pd NPs encapsulated POP (Pd-POP) was fully characterized using several techniques. Further studies revealed an excellent capability of Pd-POP for catalytic transfer hydrogenation of alkenes at room temperature with superior catalytic performance and high selectivity of desired products. Highly flammable H2 gas balloon at high pressure and temperature used in conventional hydrogenation reactions was not needed in the present synthetic system. Catalytic activity is strongly dependent on the size of encapsulated Pd NPs in the POP. The Pd-POP catalyst with Pd NPs of 8 nm in diameter exhibited higher catalytic activity for alkene hydrogenation as compared with the Pd-POP catalyst encapsulating 3 nm Pd NPs. Computational studies were undertaken to gain insights into different catalytic activities of these two Pd-POP catalysts. High reusability and stability as well as no Pd leaching of these Pd-POP catalysts make them highly applicable for hydrogenation reactions at room temperature. PMID:27258184

  16. Air-water transfer of hydrogen sulfide

    DEFF Research Database (Denmark)

    Yongsiri, C.; Vollertsen, J.; Rasmussen, M. R.;

    2004-01-01

    The emissions process of hydrogen sulfide was studied to quantify air–water transfer of hydrogen sulfide in sewer networks. Hydrogen sulfide transfer across the air–water interface was investigated at different turbulence levels (expressed in terms of the Froude number) and pH using batch...... experiments. By means of the overall mass–transfer coefficient (KLa), the transfer coefficient of hydrogen sulfide (KLaH2S), referring to total sulfide, was correlated to that of oxygen (KLaO2) (i.e., the reaeration coefficient). Results demonstrate that both turbulence and pH in the water phase play...... a significant role for KLaH2S. An exponential expression is a suitable representation for the relationship between KLaH2S and the Froude number at all pH values studied (4.5 to 8.0). Because of the dissociation of hydrogen sulfide, KLaH2S increased with decreasing pH at a constant turbulence level. Relative...

  17. Modeling of vehicular hydrogen storage transfer processes

    International Nuclear Information System (INIS)

    The acceptability in society of the conversion to the use of hydrogen as an alternate fuel for vehicles depends on hydrogen's performance in properties that are most evident to the user. While the behaviour of the vehicle with respect to power and response is an important aspect to be considered, the handling of the fuel during the transfer operation to the vehicle is also critical. This study specifically involves the transfer of fuel by developing methods comparing the fueling processes for a variety of hydrogen storage methods on a vehicle. Using computer-modeling methods to simulate various hydrogen storage systems, characteristics of different transfer processes can be compared. These characteristics include the thermodynamics involving the transfer of the hydrogen from a defined initial condition to its final state on the vehicle. Energy requirements, temperature and pressure variations, as well as limitations pertaining to the transfer rate are tabulated. Dynamic models simulate the fueling procedure and characterize the components from the initial to the final equilibrium state within the vehicle and illustrate the fluctuations in the systems during the physical transfer operations. Availability of these models are intended to aid with the research regarding the improvement of the transfer rates as well as lessening the complexity and increasing the safety of the fueling process. Safety concerns range from passive risks from toxic and low temperature or cryogenic effects, to more severe catastrophic events such as explosion and combustion. Recognizing that the examination of safety is more subjective in nature than other properties being modeled, non-conventional methods of analysis were considered. It was decided that the application of fuzzy analysis to the results of survey studies was to be utilized. A description of the method of analysis being developed follows an introduction to the use of fuzzy logic. (author)

  18. Support nanostructure boosts oxygen transfer to catalytically active platinum nanoparticles

    Science.gov (United States)

    Vayssilov, Georgi N.; Lykhach, Yaroslava; Migani, Annapaola; Staudt, Thorsten; Petrova, Galina P.; Tsud, Nataliya; Skála, Tomáš; Bruix, Albert; Illas, Francesc; Prince, Kevin C.; MatolíN, VladimíR.; Neyman, Konstantin M.; Libuda, Jörg

    2011-04-01

    Interactions of metal particles with oxide supports can radically enhance the performance of supported catalysts. At the microscopic level, the details of such metal-oxide interactions usually remain obscure. This study identifies two types of oxidative metal-oxide interaction on well-defined models of technologically important Pt-ceria catalysts: (1) electron transfer from the Pt nanoparticle to the support, and (2) oxygen transfer from ceria to Pt. The electron transfer is favourable on ceria supports, irrespective of their morphology. Remarkably, the oxygen transfer is shown to require the presence of nanostructured ceria in close contact with Pt and, thus, is inherently a nanoscale effect. Our findings enable us to detail the formation mechanism of the catalytically indispensable Pt-O species on ceria and to elucidate the extraordinary structure-activity dependence of ceria-based catalysts in general.

  19. Dynamic\tmodelling of catalytic three-phase reactors for hydrogenation and oxidation processes

    Directory of Open Access Journals (Sweden)

    Salmi T.

    2000-01-01

    Full Text Available The dynamic modelling principles for typical catalytic three-phase reactors, batch autoclaves and fixed (trickle beds were described. The models consist of balance equations for the catalyst particles as well as for the bulk phases of gas and liquid. Rate equations, transport models and mass balances were coupled to generalized heterogeneous models which were solved with respect to time and space with algorithms suitable for stiff differential equations. The aspects of numerical solution strategies were discussed and the procedure was illustrated with three case studies: hydrogenation of aromatics, hydrogenation of aldehydes and oxidation of ferrosulphate. The case studies revealed the importance of mass transfer resistance inside the catalyst pallets as well as the dynamics of the different phases being present in the reactor. Reliable three-phase reactor simulation and scale-up should be based on dynamic heterogeneous models.

  20. Study and manufacture of a para-/ortho-hydrogen catalytic converter for a space cryostat

    Science.gov (United States)

    Baston, A. H.; Bradshaw, T. W.; Butler, G.; Clark, N. S.; Chadwick, A. T.; Harris, D. H. C.; Leach, F.; Norris, J. O. W.; Price, D.

    1986-01-01

    The design and optimization of a para-/ortho-hydrogen converter to increase the efficiency and lifetime of the hydrogen cryogenic system of the ISO project are described. Catalyst technology and associated heat transfer technology is evaluated. Four catalyst systems were characterized. Their catalytic activity under the orbital conditions anticipated for the three radiation shields of ISO are reported. Results from experiments on in situ deactivation and reactivation are given, indicating that this is a key parameter. Iron oxide gel is the most promising catalyst system. A full scale prototype converter was designed to ESTEC specifications, and three converters were manufactured and tested. Performance, except for two small details, meets or exceeds specification. Plans for the development and testing of flight unit converters are proposed.

  1. 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

  2. Graphene oxide based chiral diamine rhodium catalyst for asymmetric transfer hydrogenation of aromatic ketones

    Directory of Open Access Journals (Sweden)

    LIU Ketang

    2013-02-01

    Full Text Available Functional graphite oxide materials were synthesized through the Hummers chemical oxidation of graphite.Heterogeneous catalyst was prepared via direct grafting diamine-based chiral ligand to graphite oxide followed by the complexation with organorhodium complex.Such a chiral rhodium catalyst exhibited high catalytic activity and enantioselectivity in asymmetric transfer hydrogenation of aromatic ketones in aqueous medium under mild condition.

  3. High Selective Determination of Anionic Surfactant Using Its Parallel Catalytic Hydrogen Wave

    Institute of Scientific and Technical Information of China (English)

    过玮; 何盈盈; 宋俊峰

    2003-01-01

    A faradaic response of anionic surfactants (AS), such as linear aikylbenzene sulfonate (LAS), dodecyl benzene sulfonate and dodecyl sulfate, was observed in weak acidic medium. The faradaic response of AS includes (1) a catalytic hydrogen wave of AS in HAc/NaAc buffer that was attributed to the reduction of proton associated with the sulfo-group of AS, and (2) a parallel catalytic hydrogen wave of AS in the presence of hydrogen peroxide, which was due to the catalysis of the catalytic hydrogen wave of AS by hydroxyl radical OH electrogenerated in the reduction of hydrogen peroxide. The parallel catalytic hydrogen wave is about 50 times as sensitive as the catalytic hydrogen wave. Based on the parallel catalytic hydrogen wave, a high selective method for the determination of AS was developed. In 0.1mol/L HAc/NaAc (pH=6.2±0.1)/1.0×10-3mol/L H2O2 supporting electrolyte, the second-order derivative peak current of the parallel catalytic hydrogen wave located at-1.33 V (vs. SCE) was rectilinear to AS concentration in the range of 3.0×10-6-2.5×10-4mol/L, without the interference of other surfactants. The proposed method was evaluated by quantitative analysis of AS in environmental wastewater.

  4. Modelling of the aerosol deposition in a hydrogen catalytic recombiner

    Energy Technology Data Exchange (ETDEWEB)

    Vendel, J.; Studer, E.; Zavaleta, P. [Inst. de Protection et de Surete Nucleaire, Dept. de Prevention et d' Etudes des Accidents, Gif-sur-Yvette Cedex (France); Hadida, Ph. [Quasar Informatique, Paris (France)

    1997-03-01

    Catalytic recombiners are used to remove the hydrogen released in case of a severe accident in a nuclear power plant, so as to reduce the risk of deflagration or detonation. H{sub 2}PAR experiments are carried out to precise the behaviour of recombiners in term of poisoning by aerosols. Firstly, some calculations have been done with the Trio-EF code to assess the structure of convection loops in the experimental tent. We note that when the recombiner is active, it may have a strong influence on the flow inside the tent and may even interact with an other heat source such as a furnace. In the second part, we study the deposition of aerosols on catalytic plates for a given recombiner, when it is active or passive. We list the different mechanisms and quantify them by introducing the deposition velocity. In fact, thermophoresis appears to be the main mechanism, compared to brownian diffusion or difrusiophoresis, which governs aerosols deposition. It favours deposition on <> plates and acts against it for <> plates. (author)

  5. Modelling of the aerosol deposition in a hydrogen catalytic recombiner

    International Nuclear Information System (INIS)

    Catalytic recombiners are used to remove the hydrogen released in case of a severe accident in a nuclear power plant, so as to reduce the risk of deflagration or detonation. H2PAR experiments are carried out to precise the behaviour of recombiners in term of poisoning by aerosols. Firstly, some calculations have been done with the Trio-EF code to assess the structure of convection loops in the experimental tent. We note that when the recombiner is active, it may have a strong influence on the flow inside the tent and may even interact with an other heat source such as a furnace. In the second part, we study the deposition of aerosols on catalytic plates for a given recombiner, when it is active or passive. We list the different mechanisms and quantify them by introducing the deposition velocity. In fact, thermophoresis appears to be the main mechanism, compared to brownian diffusion or difrusiophoresis, which governs aerosols deposition. It favours deposition on > plates and acts against it for > plates. (author)

  6. Mass transfer in liquid phase catalytic exchange column of trickle bed type

    International Nuclear Information System (INIS)

    The mechanism of mass transfer in a liquid phase catalytic exchange column was discussed for a trickle bed type. A new model has been proposed on the basis of this mass transfer mechanism; and several problems for the previous reported models were pointed out in the derivation of the model. An overall rate equation was first derived from the vapor-hydrogen exchange in the model. The mass transfer for the vapor-hydrogen exchange was decomposed to the following three steps: the mass transfer in a gas boundary layer on a catalyst particle; the mass transfer within the pores in the catalyst; and the chemical reaction on the surface of the catalyst. The water-vapor scrubbing process was considered as a series of the mass transfers in gas and liquid boundary layers on the wetted surfaces of the catalyst and packings or wall of the column. Significant subjects to be studied were proposed from the viewpoint of the validity of the model and the optimization of the column. (author)

  7. Catalytic hydrogen evolution from water by reduced forms of 12-tungstosilicic acid in the presence of heterogeneous rhodium polymeric catalysts

    International Nuclear Information System (INIS)

    Catalytic effect of heterogeneous rhodium-polymeric catalyst on the hydrogen evolution from aqueous and aqueous-alcohol solutions of slightly reduced forms of 12-tungstosilic acid has been studied. The activity of the catalyst studied under experimental conditions is limited by the reagent diffusion from the solution volume. It is found, that heteropolyacid ions, immobilized on the polymer together with fine-dispersed particles of metallic rhodium, take active part in the electron transfer from the solution volume onto metallic particles inside a polymeric carriei thus promoting the catalytic process

  8. Experimental studies on catalytic hydrogen recombiners for light water reactors

    International Nuclear Information System (INIS)

    In the course of core melt accidents in nuclear power plants a large amount of hydrogen can be produced and form an explosive or even detonative gas mixture with aerial oxygen in the reactor building. In the containment atmosphere of pressurized water reactors hydrogen combines a phlogistically with the oxygen present to form water vapor even at room temperature. In the past, experimental work conducted at various facilities has contributed little or nothing to an understanding of the operating principles of catalytic recombiners. Hence, the purpose of the present study was to conduct detailed investigations on a section of a recombiner essentially in order to deepen the understanding of reaction kinetics and heat transport processes. The results of the experiments presented in this dissertation form a large data base of measurements which provides an insight into the processes taking place in recombiners. The reaction-kinetic interpretation of the measured data confirms and deepens the diffusion theory - proposed in an earlier study. Thus it is now possible to validate detailed numeric models representing the processes in recombiners. Consequently the present study serves to broaden and corroborate competence in this significant area of reactor technology. In addition, the empirical knowledge thus gained may be used for a critical reassessment of previous numeric model calculations. (orig.)

  9. Recent advances in catalytic asymmetric hydrogenation:Renaissance of the monodentate phosphorus ligands

    Institute of Scientific and Technical Information of China (English)

    GUO Hongchao; DING Kuiling; DAI Lixin

    2004-01-01

    The history for the development of chiral phosphorus ligands in catalytic asymmetric hydrogenation is briefly highlighted. This review focuses on the recent advances in the synthesis of the monodentate phosphorus ligands and their applications in catalytic asymmetric hydrogenation. The examples highlighted in this article clearly demonstrated the importance and advantages of monodentate phosphorus ligands, which had been ignored for 30 a and experienced a renaissance at the very beginning of this millennium, particularly in the area of asymmetric hydrogenation.

  10. Hydrogen production by catalytic gasification of cellulose in supercritical water

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    Cellulose,one of the important components of biomass,was gasified in supercritical water to produce hydrogen-rich gas in an autoclave which was operated batch-wise under high-pressure.K2CO3 and Ca(OH)2 were selected as the catalysts (or promoters).The temperature was kept between 450℃ and 500℃ while pressure was maintained at 24-26 MPa.The reaction time was 20 min.Experimental results showed that the two catalysts had good catalytic effect and optimum amounts were observed for each catalyst.When 0.2 g K2CO3 was added,the hydrogen yield could reach 9.456 mol.kg-1 which was two times of the H2 amount produced without catalyst.When 1.6 g Ca(OH)2 was added,the H2 yield was K2CO3 as catalyst but is still 1.7 times that achieved without catalyst.Comparing with the results obtained using KaCO3 or Ca(OH)2 alone,the use of a combination of K2CO3 and Ca(OH)2 could increase the H2 yield by up to 2.5 times that without catalyst and 25% and 45% more than that obtained using K2CO3 and Ca(OH)2 alone,respectively.It was found that methane was the dominant product at relatively low temperature.When the temperature was increased,the methane reacts with water and is converted to hydrogen and carbon dioxide.

  11. Alloying effects on hydrogen permeability of V without catalytic Pd overlayer

    Energy Technology Data Exchange (ETDEWEB)

    Nakamura, Y.; Yukawa, H.; Suzuki, A. [Department of Materials Science and Engineering, Graduate School of Engineering, Nagoya University, Furo-cho, Chikusa-ku, Nagoya, Aichi 464-8603 (Japan); Nambu, T. [Department of Materials Science and Engineering, Suzuka National College of Technology, Shiroko-cho, Suzuka, Mie 510-0294 (Japan); Matsumoto, Y. [Department of Mechanical Engineering, Oita National College of Technology, Maki, Oita 870-0152 (Japan); Murata, Y. [Department of Materials Science and Engineering, Graduate School of Engineering, Nagoya University, Furo-cho, Chikusa-ku, Nagoya, Aichi 464-8603 (Japan)

    2015-10-05

    Highlights: • Air–treated V–based alloy membranes without catalytic Pd overlayer are found to possess excellent hydrogen permeability. • They also exhibit good durability at high temperature. • Alloying effects are discussed in view of the new description of hydrogen permeation based on hydrogen chemical potential. - Abstract: Hydrogen permeability of air–treated V–based alloy membranes without Pd coating have been investigated. The diffusion–limiting hydrogen permeation reaction takes place even without catalytic Pd overlayer on the surface. It is shown that pure V and its alloy membranes without Pd overlayer possess excellent hydrogen permeability and good durability at high temperature. The new description of hydrogen permeation based on hydrogen chemical potential has been applied and the hydrogen flux is analyzed in terms of the mobility of hydrogen atom and the PCT factor, f{sub PCT}.

  12. Simulation of hydrogen mitigation in catalytic recombiner. Part-II: Formulation of a CFD model

    Energy Technology Data Exchange (ETDEWEB)

    Prabhudharwadkar, Deoras M. [Department of Mechanical Engineering, Indian Institute of Technology-Bombay, Powai, Mumbai 400076 (India); Iyer, Kannan N., E-mail: kiyer@me.iitb.ac.i [Department of Mechanical Engineering, Indian Institute of Technology-Bombay, Powai, Mumbai 400076 (India)

    2011-05-15

    Research highlights: Hydrogen transport in containment with recombiners is a multi-scale problem. A novel methodology worked out to lump the recombiner characteristics. Results obtained using commercial code FLUENT are cast in the form of correlations. Hence, coarse grids can obtain accurate distribution of H{sub 2} in containment. Satisfactory working of the methodology is clearly demonstrated. - Abstract: This paper aims at formulation of a model compatible with CFD code to simulate hydrogen distribution and mitigation using a Passive Catalytic Recombiner in the Nuclear power plant containments. The catalytic recombiner is much smaller in size compared to the containment compartments. In order to fully resolve the recombination processes during the containment simulations, it requires the geometric details of the recombiner to be modelled and a very fine mesh size inside the recombiner channels. This component when integrated with containment mixing calculations would result in a large number of mesh elements which may take large computational times to solve the problem. This paper describes a method to resolve this simulation difficulty. In this exercise, the catalytic recombiner alone was first modelled in detail using the best suited option to describe the reaction rate. A detailed parametric study was conducted, from which correlations for the heat of reaction (hence the rate of reaction) and the heat transfer coefficient were obtained. These correlations were then used to model the recombiner channels as single computational cells providing necessary volumetric sources/sinks to the energy and species transport equations. This avoids full resolution of these channels, thereby allowing larger mesh size in the recombiners. The above mentioned method was successfully validated using both steady state and transient test problems and the results indicate very satisfactory modelling of the component.

  13. Hydrogen catalytic currents in solutions of molybdenum complexes with 8-hydroxyquinoline

    International Nuclear Information System (INIS)

    To clarify the possibility of manifestation of catalytic effect of Mo(6) complex with 8-hydroxyquinoline in electrochemical hydrogen evolution the polarographic behaviour of the given complex is studied. During Mo(6) electroreduction on a mercury-dropping electrode in the presence of 8-hydroxyquinoline at the background of 2x10-3 M HCl in the range of potentials -1.1--1.15 V the catalytic wave of hydrogen is observed. Catalytic current reaches the maximum value in pH range 2.4-2.8 and it is in a linear dependence on Mo(6) concentration in the concentration range 10-7-2x10-8 mol/l. Catalytic effect is caused by protonation of Mo(6) complex with 8-hydroxyquinoline, adsorbed on the electrode. Adsorption of Mo(6) complex plays the most important role in the catalytic process, which promotes considerable excess of catalytic current as compared with diffusional one

  14. Solid-phase catalytic reactions of tritium with carbohydrates. Communication 3. Mechanism of isomerization of epimeric pentoses in the course of solid-phase catalytic hydrogenation with tritium

    International Nuclear Information System (INIS)

    The mechanism of isomerization of ribose into arabinose in the solid phase under the action of spillover hydrogen in the course of solid-phase catalytic hydrogenation with tritium was studied. Isomerization of ribose was shown to occur by a complex mechanism similar to acid-catalyzed keto-enol tautomerization of epimeric sugars in solution; the active species in solid-phase catalytic hydrogenation of D-ribose with tritium is spillover hydrogen in the proton form

  15. Exploring the decomposition pathways of iron asymmetric transfer hydrogenation catalysts.

    Science.gov (United States)

    Lagaditis, Paraskevi O; Sues, Peter E; Lough, Alan J; Morris, Robert H

    2015-07-21

    Our group has developed a series of iron-based asymmetric transfer hydrogenation (ATH) catalysts for the reduction of polar double bonds. The activation of the precatalysts as well as the catalytic mechanism have been thoroughly investigated, but the decomposition pathways of these systems are poorly understood. Herein, we report a study of the deactivation pathways for an iron ATH catalyst under catalytically relevant conditions. The decomposition pathways were examined using experimental techniques and density functional theory (DFT) calculations. The major decomposition products that formed, Fe(CO)((Et)2PCH2CH2CHCHNCH2CH2P(Et)2) (3a) and Fe(CO)((Et)2PCH2CH2C(Ph)C(Ph)NCH2CH2P(Et)2) (3b), had two amido donors as well as a C=C bond on the diamine backbone of the tetradentate ligand. These species were identified by NMR studies and one was isolated as a bimetallic complex with Ru(II)Cp*. Two minor iron hydride species also formed concurrently with 3a, as determined by NMR studies, one of which was isolated and contained a fully saturated ligand as well as a hydride ligand. None of the compounds that were isolated were found to be active ATH catalysts. PMID:25373607

  16. A continuous flow strategy for the coupled transfer hydrogenation and etherification of 5-(hydroxymethyl)furfural using Lewis acid zeolites.

    Science.gov (United States)

    Lewis, Jennifer D; Van de Vyver, Stijn; Crisci, Anthony J; Gunther, William R; Michaelis, Vladimir K; Griffin, Robert G; Román-Leshkov, Yuriy

    2014-08-01

    Hf-, Zr- and Sn-Beta zeolites effectively catalyze the coupled transfer hydrogenation and etherification of 5-(hydroxymethyl)furfural with primary and secondary alcohols into 2,5-bis(alkoxymethyl)furans, thus making it possible to generate renewable fuel additives without the use of external hydrogen sources or precious metals. Continuous flow experiments reveal nonuniform changes in the relative deactivation rates of the transfer hydrogenation and etherification reactions, which impact the observed product distribution over time. We found that the catalysts undergo a drastic deactivation for the etherification step while maintaining catalytic activity for the transfer hydrogenation step. (119) Sn and (29) Si magic angle spinning (MAS) NMR studies show that this deactivation can be attributed to changes in the local environment of the metal sites. Additional insights were gained by studying effects of various alcohols and water concentration on the catalytic reactivity. PMID:25045144

  17. Ruthenium(II) pincer complexes with oxazoline arms for efficient transfer hydrogenation reactions

    KAUST Repository

    Chen, Tao

    2012-08-01

    Well-defined P NN CN pincer ruthenium complexes bearing both strong phosphine and weak oxazoline donors were developed. These easily accessible complexes exhibit significantly better catalytic activity in transfer hydrogenation of ketones compared to their PN 3P analogs. These reactions proceed under mild and base-free conditions via protonation- deprotonation of the \\'NH\\' group in the aromatization-dearomatization process. © 2012 Elsevier Ltd. All rights reserved.

  18. Hydrogen production in a zigzag and straight catalytic wall coated micro channel reactor by CFD modeling

    Energy Technology Data Exchange (ETDEWEB)

    Fazeli, Ali; Behnam, Mohsen [Gas Research Division, Research Institute of Petroleum Industry (RIPI), P.O. Box 14665-137, Tehran (Iran)

    2010-09-15

    Hydrogen production from steam reforming of methanol for fuel cell application was modeled in a wall coated micro channel reactor by CFD approach. Heat of steam reforming (SR) was supplied from catalytic total oxidation (TOX) of methanol on Cu/ZnO/Al{sub 2}O{sub 3} catalyst and Heat conducts from TOX to SR zone through Steel divider wall between two channels. Heat integration was compared in zigzag and straight geometry of microreactor by CFD modeling. The model is two dimensional, steady state and containing five zones: TOX fluid, TOX catalyst layer, steel wall of the channel, SR catalyst layer and SR fluid. Set of partial differential equations (PDEs) including x and y momentum balance, continuity, partial mass balances and energy balance was solved by finite volume method. Stiff reaction rates were considered for methanol total oxidation (TOX), methanol steam reforming (SR), water gas shift (WGS) and methanol decomposition (MD) reactions. The results show that zigzag geometry is better than straight one because heat and mass transfer in zigzag reactor are more than straight. Conversion of methanol in zigzag geometry is greater than straight one. In the outlet of zigzag micro channels, carbon monoxide selectivity is less and hydrogen mole fraction is more than straight one. (author)

  19. Improved performance in coprocessing through fundamental and mechanistic studies in hydrogen transfer and catalysis. Quarterly report, September 27, 1990--December 26, 1990

    Energy Technology Data Exchange (ETDEWEB)

    Curtis, C.W.

    1990-12-31

    The objective is to gain a fundamental understanding of the role and importance of hydrogen transfer reactions in thermal and catalytic coprocessing by examining possible hydrogen donation from cycloalkane/aromatic systems and by understanding the chemistry and enhanced reactivity of hydrotreated residuum, as well as by enriching petroleum solvent with potent new donors, nonaromatic hydroaromatics, thereby promoting hydrogen transfer reactions in coprocessing. The detailed results of experiments performed on several subtasks during the quarter are presented.

  20. Capture and transfer of pions in hydrogenous materials

    International Nuclear Information System (INIS)

    Pionic hydrogen is a short-lived exotic hydrogen isotope in which a negative pion replaces the atomic electron. The formation and subsequent interactions of pionic hydrogen are discussed, with emphasis on the process of pion transfer. Recent results using the pion charge-exchange reaction (π-, π0) obtained at TRIUMF are reviewed. (Author) (35 refs., 3 tabs., 9 figs.)

  1. Catalytic hydrogenation using complexes of base metals with tridentate ligands

    Energy Technology Data Exchange (ETDEWEB)

    Vasudevan, Kalyan V.; Zhang, Guoqi; Hanson, Susan K.

    2016-09-06

    Complexes of cobalt and nickel with tridentate ligand PNHP.sup.R are effective for hydrogenation of unsaturated compounds. Cobalt complex [(PNHP.sup.Cy)Co(CH.sub.2SiMe.sub.3)]BAr.sup.F.sub.4 (PNHP.sup.Cy=bis[2-(dicyclohexylphosphino)ethyl]amine, BAr.sup.F.sub.4=B(3,5-(CF.sub.3).sub.2C.sub.6H.sub.3).sub.4)) was prepared and used with hydrogen for hydrogenation of alkenes, aldehydes, ketones, and imines under mild conditions (25-60.degree. C., 1-4 atm H.sub.2). Nickel complex [(PNHP.sup.Cy)Ni(H)]BPh.sub.4 was used for hydrogenation of styrene and 1-octene under mild conditions. (PNP.sup.Cy)Ni(H) was used for hydrogenating alkenes.

  2. Chemistry and catalysis of coal liquefaction: catalytic and thermal upgrading of coal liquid and hydrogenation of CO to produce fuels. Quarterly progress report, January-March 1980

    Energy Technology Data Exchange (ETDEWEB)

    Wiser, W.H.

    1980-08-01

    Analysis of a group of coal liquids produced by catalytic hydrogenation of Utah coals with ZnCl/sub 2/ catalyst was begun. Carbon-13 nuclear magnetic resonance and liquid chromatography techniques will be used to correlate chemical properties with hydrogenation reactivity. Equipment previously used for downflow measurements of heat and momentum transfer in a gas-coal suspension was modified for upflow measurements. The catalytic hydrodeoxygenation of methyl benzoate has been studied to elucidate the reactions of ester during upgrading of coal-derived liquids. The kinetics of hydrogenation of phenanthrene have also been determined. The catalytic cracking mechanism of octahydroanthracene is reported in detail. Studies of the hydrodesulfurization of thiophene indicate that some thiophene is strongly adsorbed as a hydrogen-deficient polymer on cobalt-molybdate catalyst. Part of the polymer can be desorbed as thiophene by hydrogenation. Poisoning of the catalyst inhibits the hydrosulfurization activity to a greater degree than the hydrogenation activity. Iron-manganese catalysts for carbon monoxide hydrogenation is studied to determine the role of iron carbide formation on selectivity. Pure iron catalyst forms a Hagg iron carbide phase under reaction conditions.

  3. Maximizing renewable hydrogen production from biomass in a bio/catalytic refinery

    DEFF Research Database (Denmark)

    Westermann, Peter; Jørgensen, Betina; Lange, L.;

    2007-01-01

    photofermentative production. Due to these constraints biological hydrogen production from biomass has so far not been considered a significant source in most scenarios of a future hydrogen-based economy. In this review we briefly summarize the current state of art of biomass-based hydrogen production and suggest a......Biological production of hydrogen from biomass by fermentative or photofermentative microorganisms has been described in numerous research articles and reviews. The major challenge of these techniques is the low yield from fermentative production, and the large reactor volumes necessary for...... combination of a biorefinery for the production of multiple fuels (hydrogen, ethanol, and methane) and chemical catalytic technologies which could lead to a yield of 10-12 mol hydrogen per mol glucose derived from biological waste products. Besides the high hydrogen yield, the advantage of the suggested...

  4. Tunable Molecular MoS2 Edge-Site Mimics for Catalytic Hydrogen Production.

    Science.gov (United States)

    Garrett, Benjamin R; Polen, Shane M; Click, Kevin A; He, Mingfu; Huang, Zhongjie; Hadad, Christopher M; Wu, Yiying

    2016-04-18

    Molybdenum sulfides represent state-of-the-art, non-platinum electrocatalysts for the hydrogen evolution reaction (HER). According to the Sabatier principle, the hydrogen binding strength to the edge active sites should be neither too strong nor too weak. Therefore, it is of interest to develop a molecular motif that mimics the catalytic sites structurally and possesses tunable electronic properties that influence the hydrogen binding strength. Furthermore, molecular mimics will be important for providing mechanistic insight toward the HER with molybdenum sulfide catalysts. In this work, a modular method to tune the catalytic properties of the S-S bond in MoO(S2)2L2 complexes is described. We studied the homogeneous electrocatalytic hydrogen production performance metrics of three catalysts with different bipyridine substitutions. By varying the electron-donating abilities, we present the first demonstration of using the ligand to tune the catalytic properties of the S-S bond in molecular MoS2 edge-site mimics. This work can shed light on the relationship between the structure and electrocatalytic activity of molecular MoS2 catalysts and thus is of broad importance from catalytic hydrogen production to biological enzyme functions. PMID:27022836

  5. Oxidation of hydrogen halides to elemental halogens with catalytic molten salt mixtures

    Science.gov (United States)

    Rohrmann, Charles A.

    1978-01-01

    A process for oxidizing hydrogen halides by means of a catalytically active molten salt is disclosed. The subject hydrogen halide is contacted with a molten salt containing an oxygen compound of vanadium and alkali metal sulfates and pyrosulfates to produce an effluent gas stream rich in the elemental halogen. The reduced vanadium which remains after this contacting is regenerated to the active higher valence state by contacting the spent molten salt with a stream of oxygen-bearing gas.

  6. Hydrogen Storage in High Surface Area Carbon Nanotubes Produced by Catalytic Chemical Vapor Deposition

    OpenAIRE

    Bacsa, Revathi; Laurent, Christophe; Morishima, Ryuta; Suzuki, Hiroshi; Le Lay, Mikako

    2004-01-01

    Carbon nanotubes, mostly single- and double-walled, are prepared by a catalytic chemical vapor deposition method using H2-CH4 atmospheres with different CH4 contents. The maximum hydrogen storage at room temperatures and 10 MPa is 0.5 wt %. Contrary to expectations, purification of the carbon nanotube specimens by oxidative acid treatments or by heating in inert gas decreases the hydrogen storage. Decreasing the residual catalyst content does not necessarily lead to an increase in ASH. Moreov...

  7. 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

  8. Preparation of Hydrogen through Catalytic Steam Reforming of Bio-oil

    Institute of Scientific and Technical Information of China (English)

    吴层; 颜涌捷; 李庭琛; 亓伟

    2007-01-01

    Hydrogen was prepared via catalytic steam reforming of bio-oil which was obtained from fast pyrolysis of biomass in a fluidized bed reactor. Influential factors including temperature, weight hourly space velocity (WHSV) of bio-oil, mass ratio of steam to bio-oil (S/B) as well as catalyst type on hydrogen selectivity and other desirable gas products were investigated. Based on hydrogen in stoichiometric potential and carbon balance in gaseous phase and feed, hydrogen yield and carbon selectivity were examined. The experimental results show that higher temperature favors the hydrogen selectivity by H2 mole fraction in gaseous products stream and it plays an important role in hydrogen yield and carbon selectivity. Higher hydrogen selectivity and yield, and carbon selectivity were obtained at lower bio-oil WHSV. In catalytic steam reforming system a maximum steam concentration value exists, at which hydrogen selectivity and yield, and carbon selectivity keep constant. Through experiments, preferential operation conditions were obtained as follows: temperature 800~850℃, bio-oil WHSV below 3.0 h-1, and mass ratio of steam to bio-oil 10~12. The performance tests indicate that Ni-based catalysts are optional, especially Ni/a-Al2O3 effective in the steam reforming process.

  9. A selective hydrogen peroxide sensor based on chemiresistive polyaniline nanowires modified with silver catalytic nanoparticles

    International Nuclear Information System (INIS)

    This paper presents a novel method to selectively detect hydrogen peroxide using a chemiresistive polyaniline nanowire network. The polyaniline nanowires modified with silver catalytic nanoparticles were demonstrated to give selective responses to hydrogen peroxide by changing the conductivity of the polyaniline. The proposed mechanism for the selectivity in the H2O2 sensing is based on a catalytic reaction between the silver nanoparticles and the hydrogen peroxide which generates hydroxide ions and water to influence the conductivity of polyaniline. The catalytic effect of the silver nanoparticles was confirmed by characterizing the relationship between the amount of catalysts and the current response. The results indicate that the rate of the catalytic reaction is proportional to the number of silver nanoparticles attached on the surfaces of polyaniline. By observing the conductance change, the developed chemiresistive sensor was able to selectively detect H2O2 while exhibiting minimal response to other chemical species. The objective of this paper is to address the selectivity issue of a chemiresistor by suggesting a catalyst-based selective detection of an analyte for a polyaniline-based chemiresistive sensor. This technology may have potential applications in microscale or microfluidic chemical and biological sensors requiring a selective detection of hydrogen peroxide concentrations. (paper)

  10. Low temperature catalytic combustion of natural gas - hydrogen - air mixtures

    Energy Technology Data Exchange (ETDEWEB)

    Newson, E.; Roth, F. von; Hottinger, P.; Truong, T.B. [Paul Scherrer Inst. (PSI), Villigen (Switzerland)

    1999-08-01

    The low temperature catalytic combustion of natural gas - air mixtures would allow the development of no-NO{sub x} burners for heating and power applications. Using commercially available catalysts, the room temperature ignition of methane-propane-air mixtures has been shown in laboratory reactors with combustion efficiencies over 95% and maximum temperatures less than 700{sup o}C. After a 500 hour stability test, severe deactivation of both methane and propane oxidation functions was observed. In cooperation with industrial partners, scaleup to 3 kW is being investigated together with startup dynamics and catalyst stability. (author) 3 figs., 3 refs.

  11. Catalytic Metal Free Production of Large Cage Structure Carbon Particles: A Candidate for Hydrogen Storage

    Science.gov (United States)

    Kimura, Yuki; Nuth, Joseph A., III; Ferguson, Frank T.

    2005-01-01

    We will demonstrate that carbon particles consisting of large cages can be produced without catalytic metal. The carbon particles were produced in CO gas as well as by introduction of 5% methane gas into the CO gas. The gas-produced carbon particles were able to absorb approximately 16.2 wt% of hydrogen. This value is 2.5 times higher than the 6.5 wt% goal for the vehicular hydrogen storage proposed by the Department of Energy in the USA. Therefore, we believe that this carbon particle is an excellent candidate for hydrogen storage for fuel cells.

  12. Variation of geometries and electron properties along proton transfer in strong hydrogen-bond complexes

    Science.gov (United States)

    Pacios, L. F.; Gálvez, O.; Gómez, P. C.

    2005-06-01

    Proton transfer in hydrogen-bond systems formed by 4-methylimidazole in both neutral and protonated cationic forms and by acetate anion are studied by means of MP2/6-311++G(d,p) ab initio calculations. These two complexes model the histidine (neutral and protonated)-aspartate diad present in the active sites of enzymes the catalytic mechanism of which involves the formation of strong hydrogen bonds. We investigate the evolution of geometries, natural bond orbital populations of bonds and electron lone pairs, topological descriptors of the electron density, and spatial distributions of the electron localization function along the process N-H ⋯O→N⋯H⋯O→N⋯H-O, which represents the stages of the H-transfer. Except for a sudden change in the population of electron lone pairs in N and O at the middle N...H...O stage, all the properties analyzed show a smooth continuous behavior along the covalent → hydrogen bond transit inherent to the transfer, without any discontinuity that could identify a formation or breaking of the hydrogen bond. This way, the distinction between covalent or hydrogen-bonding features is associated to subtle electron rearrangement at the intermolecular space.

  13. Catalytic mechanism of transition-metal compounds on Mg hydrogen sorption reaction.

    Science.gov (United States)

    Barkhordarian, Gagik; Klassen, Thomas; Bormann, Rüdiger

    2006-06-01

    The catalytic mechanisms of transition-metal compounds during the hydrogen sorption reaction of magnesium-based hydrides were investigated through relevant experiments. Catalytic activity was found to be influenced by four distinct physico-thermodynamic properties of the transition-metal compound: a high number of structural defects, a low stability of the compound, which however has to be high enough to avoid complete reduction of the transition metal under operating conditions, a high valence state of the transition-metal ion within the compound, and a high affinity of the transition-metal ion to hydrogen. On the basis of these results, further optimization of the selection of catalysts for improving sorption properties of magnesium-based hydrides is possible. In addition, utilization of transition-metal compounds as catalysts for other hydrogen storage materials is considered. PMID:16771356

  14. Selective catalytic reduction of nitrogen oxides from industrial gases by hydrogen or methane

    International Nuclear Information System (INIS)

    This work deals with the selective catalytic reduction of nitrogen oxides (NOx), contained in the effluents of industrial plants, by hydrogen or methane. The aim is to replace ammonia, used as reducing agent, in the conventional process. The use of others reducing agents such as hydrogen or methane is interesting for different reasons: practical, economical and ecological. The catalyst has to convert selectively NO into N2, in presence of an excess of oxygen, steam and sulfur dioxide. The developed catalyst is constituted by a support such as perovskites, particularly LaCoO3, on which are dispersed noble metals (palladium, platinum). The interaction between the noble metal and the support, generated during the activation of the catalyst, allows to minimize the water and sulfur dioxide inhibitor phenomena on the catalytic performances, particularly in the reduction of NO by hydrogen. (O.M.)

  15. The Catalytic Role of Coronene for Molecular Hydrogen Formation

    DEFF Research Database (Denmark)

    Mennella, Vito; Hornekær, Liv; Thrower, John; Accolla, Mario

    2012-01-01

    We present the results of an experimental study on the interaction of atomic deuterium with coronene films. The effects of D atom irradiation have been analyzed with infrared spectroscopy. The spectral changes provide evidence for deuteration of the outer edge coronene C sites via a D addition...... reaction. A cross section of 1.1Å2 is estimated for the deuteration process of coronene. HD and D2 molecules form, through abstraction reactions, on deuterated coronene sites with a cross section of 0.06Å2. The magnitude of both cross sections is in line with an Eley–Rideal type process. The results...... showthat hydrogenated neutral polycyclic aromatic hydrocarbon molecules act as catalysts for the formation of molecular hydrogen....

  16. Catalytic dehydrogenation of isobutane in the presence of hydrogen over Cs-modified Ni2P supported on active carbon

    International Nuclear Information System (INIS)

    Graphical abstract: - Highlights: • Ni2P catalyst is tested in dehydrogenation of isobutane for the first time. • The effects of Cs promoter on catalytic performance of Ni2P/AC were investigated. • Cs-Ni2P/AC exhibits high activity and selectivity for isobutane dehydrogenation. - Abstract: In this article, an environmentally friendly non-noble-metal class of Cs-Ni2P/active carbon (AC) catalyst was prepared and demonstrated to exhibit enhanced catalytic performance in isobutane dehydrogenation. The results of activity tests reveal that Ni/AC catalyst was highly active for isobutane cracking, which led to the formation of abundant methane and coke. After the introduction of phosphorus through impregnation with ammonium di-hydrogen phosphate and H2-temperature programmed reduction, undesired cracking reactions were effectively inhibited, and the selectivity to isobutene and stability of catalyst increased remarkably. The characterization results indicate that, after the addition of phosphorous, the improvement of dehydrogenation selectivity is ascribed to the partial positive charges carried on Ni surface in Ni2P particles, which decreases the strength of Ni-C bond between Ni and carbonium-ion intermediates and the possibility of excessive dehydrogenation. In addition, Cs-modified Ni2P/AC catalysts display much higher catalytic performance as compared to Ni2P/AC catalyst. Cs-Ni2P-6.5 catalyst has the highest catalytic performance, and the selectivity to isobutene higher than 93% can be obtained even after 4 h reaction. The enhancement in catalytic performance of the Cs-modified catalysts is mainly attributed to the function of Cs to improve the dispersion of Ni2P particles, transfer electron from Cs to Ni, and decrease acid site number and strength

  17. Homogeneous Catalytic Hydrogenations and Photocatalytic Reactions in Microstructured Reactor Systems

    Czech Academy of Sciences Publication Activity Database

    Pavlorková, Jana; Křišťál, Jiří; Drhová, Magdalena; Hejda, S.; Klusoň, Petr

    Prague: Czech Society of Industrial Chemistry, 2014 - (Kalenda, P.; Lubojacký, J.), s. 231-232 ISBN 978-80-86238-64-7. [mezinárodní chemicko-technologická konference /2./. Mikulov (CZ), 07.04.2014-09.04.2014] Institutional support: RVO:67985858 Keywords : microstructured reactor * hydrogenation * photochemical oxidation Subject RIV: CI - Industrial Chemistry, Chemical Engineering http://www.icct.cz

  18. Catalytic Hydrogenation of Bio-Oil for Chemicals and Fuels

    Energy Technology Data Exchange (ETDEWEB)

    Elliott, Douglas C.

    2006-02-14

    The scope of work includes optimizing processing conditions and demonstrating catalyst lifetime for catalyst formulations that are readily scaleable to commercial operations. We use a bench-scale, continuous-flow, packed-bed, catalytic, tubular reactor, which can be operated in the range of 100-400 mL/hr., from 50-400 C and up to 20MPa (see Figure 1). With this unit we produce upgraded bio-oil from whole bio-oil or useful bio-oil fractions, specifically pyrolytic lignin. The product oils are fractionated, for example by distillation, for recovery of chemical product streams. Other products from our tests have been used in further testing in petroleum refining technology at UOP and fractionation for product recovery in our own lab. Further scale-up of the technology is envisioned and we will carry out or support process design efforts with industrial partners, such as UOP.

  19. CATALYTICALLY ENHANCED SYSTEMS FOR HYDROGEN STORAGE. Final report

    International Nuclear Information System (INIS)

    Previous U.S. DOE sponsored research at the University of Hawaii resulted in the development of methods of doping of sodium aluminum hydride, NaAlH4 with titanium, zirconium and other catalysts such that: dehydriding occurs at temperatures as low as 100 C; rehydriding requires less than 1 h; and >4 weight percent hydrogen can be repeatedly cycled through dehydriding/rehydriding. These materials appeared to be on the threshold of practical viability as hydrogen carriers for onboard fuel cells. However, it was apparent that further kinetic enhancement was required to achieve commercial viability. Thus, one of the primary goals of this project was to develop the requisite improved catalysts. Over the course of this project, a variety of titanium and zirconium dopant precursors were investigated. Moreover, the approach was to conduct guided search for improved catalysts by obtaining a fundamental understanding of the chemical nature of the titanium dopants and their mechanism of action. Therefore, the projected also aimed to determined the chemical nature of the titanium species that are formed upon mechanical milling of NaAlH4 with the dopant precursors through synchrotron X-ray and neutron diffraction as well as transmission electron microscopy, scanning electron microscopy, and electron paramagnetic resonance (EPR) spectroscopy. In addition to kinetic studies, insight into the mechanism of action of the dopants was gained through studies of the destabilization of hydrogen in NaAlH4 by the dopants through infrared, NMR, and anelastic spectroscopy

  20. Hydrogen Recombination Rates of Plate-type Passive Auto-catalytic Recombiner

    International Nuclear Information System (INIS)

    The hydrogen mitigation system may include igniters, passive autocatalytic recombiner (PAR), and venting or dilution system. Recently PAR is commonly used as a main component of HMS in a NPP containment because of its passive nature. PARs are categorized by the shape and material of catalytic surface. Catalytic surface coated by platinum is mostly used for the hydrogen recombiners. The shapes of the catalytic surface can be grouped into plate type, honeycomb type and porous media type. Among them, the plate-type PAR is well tested by many experiments. PAR performance analysis can be approached by a multi-scale method which is composed of micro, meso and macro scales. The criterion of the scaling is the ratio of thickness of boundary layer developed on a catalytic surface to representative length of a computational domain. Mass diffusion in the boundary layer must be resolved in the micro scale analysis. In a lumped parameter (LP) analysis using a system code such as MAAP or MELCOR, the chamber of the PAR is much smaller than a computational node. The hydrogen depletion by a PAR is modeled as a source of mass and energy conservation equations. Te catalytic surface reaction of hydrogen must be modeled by a volume-averaged correlation. In this study, a micro scale analysis method is developed using libraries in OpenFOAM to evaluate a hydrogen depletion rate depending on parameters such as size and number of plates and plate arrangement. The analysis code is validated by simulating REKO-3 experiment. And hydrogen depletion analysis is conducted by changing the plate arrangement as a trial of the performance enhancement of a PAR. In this study, a numerical code for an analysis of a PAR performance in a micro scale has been developed by using OpenFOAM libraries. The physical and numerical models were validated by simulating the REKO-3 experiment. As a try to enhance the performance of the plate-type PAR, it was proposed to apply a staggered two-layer arrangement of the

  1. Hydrogen Recombination Rates of Plate-type Passive Auto-catalytic Recombiner

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Jongtae; Hong, Seong-Wan [Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of); Kim, Gun Hong [Kyungwon E-C Co., Seongnam (Korea, Republic of)

    2014-10-15

    The hydrogen mitigation system may include igniters, passive autocatalytic recombiner (PAR), and venting or dilution system. Recently PAR is commonly used as a main component of HMS in a NPP containment because of its passive nature. PARs are categorized by the shape and material of catalytic surface. Catalytic surface coated by platinum is mostly used for the hydrogen recombiners. The shapes of the catalytic surface can be grouped into plate type, honeycomb type and porous media type. Among them, the plate-type PAR is well tested by many experiments. PAR performance analysis can be approached by a multi-scale method which is composed of micro, meso and macro scales. The criterion of the scaling is the ratio of thickness of boundary layer developed on a catalytic surface to representative length of a computational domain. Mass diffusion in the boundary layer must be resolved in the micro scale analysis. In a lumped parameter (LP) analysis using a system code such as MAAP or MELCOR, the chamber of the PAR is much smaller than a computational node. The hydrogen depletion by a PAR is modeled as a source of mass and energy conservation equations. Te catalytic surface reaction of hydrogen must be modeled by a volume-averaged correlation. In this study, a micro scale analysis method is developed using libraries in OpenFOAM to evaluate a hydrogen depletion rate depending on parameters such as size and number of plates and plate arrangement. The analysis code is validated by simulating REKO-3 experiment. And hydrogen depletion analysis is conducted by changing the plate arrangement as a trial of the performance enhancement of a PAR. In this study, a numerical code for an analysis of a PAR performance in a micro scale has been developed by using OpenFOAM libraries. The physical and numerical models were validated by simulating the REKO-3 experiment. As a try to enhance the performance of the plate-type PAR, it was proposed to apply a staggered two-layer arrangement of the

  2. Hydrogen ions produced by plasma-assisted catalytic ionization using nickel grid

    International Nuclear Information System (INIS)

    Positive and negative hydrogen ions are produced by plasma-assisted catalytic ionization using a nickel grid, where the irradiation current density of positive ions onto the grid can be controlled by the discharge power. The irradiation energy can be controlled by both the grid potential and the discharge plasma potential. Extraction properties and energy distributions of positive and negative ions produced in the cases of using the grid and a porous nickel plate are compared. Two production mechanisms of negative ions are found in the process of plasma-assisted catalytic ionization

  3. Catalytic hydrogen currents in solutions of some transition metal complexes with 8-mercaptoquinoline

    International Nuclear Information System (INIS)

    Electrochemical behaviour of complexes with general formula ML2 where L-8-mercaptoquinoline, M-V(4)(VO2+) was studied. Investigations were carried out by classical and voltampere oscillographic polarography in water alcohol media. Measurements were performed at 25 deg C. It was found that chelate V(4) gives in classical polarogrammes the wave as a peak at 1.5-1.7 v depending on pH and the nature of the central ion; during electrolysis of the investigated solutions the release of gas bubbles was observed. Waves observed in the potential region 1.5-1.7 v are the catalytic waves of hydrogen. Results obtained on the catalytic activity of structurally related complexes of transitional metals with mercaptoquinoline indicate a definite influence of the central atom nature on the catalytic effect. Intermediate particles with central atom in the lower degree of oxidation formed at catalytic wave may be responsible for the catalytic effect. The rate of their formation on the electrode and the rate of their protonization determine the catalytic wave height

  4. Biomass to hydrogen via fast pyrolysis and catalytic steam reforming

    Energy Technology Data Exchange (ETDEWEB)

    Chornet, E.; Wang, D.; Montane, D. [National Renewable Energy Lab., Golden, CO (United States)] [and others

    1995-09-01

    Fast pyrolysis of biomass results in a pyrolytic oil which is a mixture of (a) carbohydrate-derived acids, aldehydes and polyols, (b) lignin-derived substituted phenolics, and (c) extractives-derived terpenoids and fatty acids. The conversion of this pyrolysis oil into H{sub 2} and CO{sub 2} is thermodynamically favored under appropriate steam reforming conditions. Our efforts have focused in understanding the catalysis of steam reforming which will lead to a successful process at reasonable steam/carbon ratios arid process severities. The experimental work, carried out at the laboratory and bench scale levels, has centered on the performance of Ni-based catalysts using model compounds as prototypes of the oxygenates present in the pyrolysis oil. Steam reforming of acetic acid, hydroxyacetaldehyde, furfural and syringol has been proven to proceed rapidly within a reasonable range of severities. Time-on-stream studies are now underway using a fixed bed barometric pressure reactor to ascertain the durability of the catalysts and thus substantiate the scientific and technical feasibility of the catalytic reforming option. Economic analyses are being carried out in parallel to determine the opportunity zones for the combined fast pyrolysis/steam reforming approach. A discussion on the current state of the project is presented.

  5. Heat transfer analysis of liquid piston compressor for hydrogen applications

    DEFF Research Database (Denmark)

    Kermani, Nasrin Arjomand; Rokni, Masoud

    2015-01-01

    A hydrogen compression technology using liquid as the compression piston is investigated from heat transfer point of view. A thermodynamic model, simulating a single compression stroke, is developed to investigate the heat transfer phenomena inside the compression chamber. The model is developed ...

  6. Synthesis of novel chiral tetraaza ligands and their application in enantioselective transfer hydrogenation of ketones

    Institute of Scientific and Technical Information of China (English)

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

    2012-01-01

    Novel chiral tetraaza ligands (R)-N,N'-bis[2-(piperidin-l-yl)benzylidene]propane-1,2-diamine 6 and (S)-N-[2-(piperidin-1-yl)benzylidene]-3-{ [2-(piperidin-1-yl)benzylidene]amino}-alanine sodium salt 7 have been synthesized and fully characterized by NMR,IR,MS and CD spectra.The catalytic property of the ligands was investigated in Ir-catalyzed enantioselective transfer hydrogenation of ketones.The corresponding optical active alcohols were obtained with high yields and moderate ees under mild reaction conditions.

  7. Mesoporous Silica-Supported Sulfonyldiamine Ligand for Microwave-Assisted Transfer Hydrogenation

    Directory of Open Access Journals (Sweden)

    Shaheen M. Sarkar

    2015-01-01

    Full Text Available N-Sulfonyl-1,2-diamine ligands, derived from 1,2-diaminocyclohexane and 1,2-diaminopropane, were immobilized onto mesoporous SBA-15 silica. The SBA-15-supported sulfonyldiamine-Ru complex was prepared in situ under microwave heating at 60 W for 3 min. The prepared sulfonyldiamine-Ru complex was used as an efficient catalyst for the transfer hydrogenation of ketones to the corresponding secondary alcohols. The heterogeneous complex showed extremely high catalytic activity with 99% conversion rate under microwave heating condition. The complexes were regenerated by simple filtration and reused two times without significant loss of activity.

  8. 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.

  9. Oxygen transport membrane system and method for transferring heat to catalytic/process reactors

    Science.gov (United States)

    Kelly, Sean M; Kromer, Brian R; Litwin, Michael M; Rosen, Lee J; Christie, Gervase Maxwell; Wilson, Jamie R; Kosowski, Lawrence W; Robinson, Charles

    2014-01-07

    A method and apparatus for producing heat used in a synthesis gas production is provided. The disclosed method and apparatus include a plurality of tubular oxygen transport membrane elements adapted to separate oxygen from an oxygen containing stream contacting the retentate side of the membrane elements. The permeated oxygen is combusted with a hydrogen containing synthesis gas stream contacting the permeate side of the tubular oxygen transport membrane elements thereby generating a reaction product stream and radiant heat. The present method and apparatus also includes at least one catalytic reactor containing a catalyst to promote the stream reforming reaction wherein the catalytic reactor is surrounded by the plurality of tubular oxygen transport membrane elements. The view factor between the catalytic reactor and the plurality of tubular oxygen transport membrane elements radiating heat to the catalytic reactor is greater than or equal to 0.5.

  10. Oxygen transport membrane system and method for transferring heat to catalytic/process reactors

    Energy Technology Data Exchange (ETDEWEB)

    Kelly, Sean M.; Kromer, Brian R.; Litwin, Michael M.; Rosen, Lee J.; Christie, Gervase Maxwell; Wilson, Jamie R.; Kosowski, Lawrence W.; Robinson, Charles

    2016-01-19

    A method and apparatus for producing heat used in a synthesis gas production process is provided. The disclosed method and apparatus include a plurality of tubular oxygen transport membrane elements adapted to separate oxygen from an oxygen containing stream contacting the retentate side of the membrane elements. The permeated oxygen is combusted with a hydrogen containing synthesis gas stream contacting the permeate side of the tubular oxygen transport membrane elements thereby generating a reaction product stream and radiant heat. The present method and apparatus also includes at least one catalytic reactor containing a catalyst to promote the steam reforming reaction wherein the catalytic reactor is surrounded by the plurality of tubular oxygen transport membrane elements. The view factor between the catalytic reactor and the plurality of tubular oxygen transport membrane elements radiating heat to the catalytic reactor is greater than or equal to 0.5

  11. Catalytic Response and Stability of Nickel/Alumina for the Hydrogenation of 5-Hydroxymethylfurfural in Water.

    Science.gov (United States)

    Perret, Noémie; Grigoropoulos, Alexios; Zanella, Marco; Manning, Troy D; Claridge, John B; Rosseinsky, Matthew J

    2016-03-01

    The catalytic response of Ni on Al2O3 obtained from Ni-Al layered double hydroxides was studied for the liquid-phase hydrogenation of hydroxymethyl furfural to tetrahydrofuran-2,5-diyldimethanol (THFDM) in water. The successive calcination and reduction of the precursors caused the removal of interlayer hydroxyl and carbonate groups and the reduction of Ni(2+) to Ni(0). Four reduced mixed oxide catalysts were obtained, consisting of different amount of Ni metal contents (47-68 wt%) on an Al-rich amorphous component. The catalytic activity was linked to Ni content whereas selectivity was mainly affected by reaction temperature. THFDM was formed in a stepwise manner at low temperature (353 K) whereas 3-hydroxymethyl cyclopentanone was generated at higher temperature. Coke formation caused deactivation; however, the catalytic activity can be regenerated using heat treatment. The results establish Ni on Al2O3 as a promising catalyst for the production of THFDM in water. PMID:26870940

  12. 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.

  13. Research of Hydrogen Preparation with Catalytic Steam-Carbon Reaction Driven by Photo-Thermochemistry Process

    Directory of Open Access Journals (Sweden)

    Xiaoqing Zhang

    2013-01-01

    Full Text Available An experiment of hydrogen preparation from steam-carbon reaction catalyzed by K2CO3 was carried out at 700°C, which was driven by the solar reaction system simulated with Xenon lamp. It can be found that the rate of reaction with catalyst is 10 times more than that without catalyst. However, for the catalytic reaction, there is no obvious change for the rate of hydrogen generation with catalyst content range from 10% to 20%. Besides, the conversion efficiency of solar energy to chemical energy is more than 13.1% over that by photovoltaic-electrolysis route. An analysis to the mechanism of catalytic steam-carbon reaction with K2CO3 is given, and an explanation to the nonbalanced [H2]/[CO + 2CO2] is presented, which is a phenomenon usually observed in experiment.

  14. Exploiting high pressure advantages in catalytic hydrogenation of carbon dioxide to methanol

    OpenAIRE

    Bansode, Atul Baban

    2014-01-01

    The aim of this thesis was to develop highly efficient CO2 hydrogenation process towards methanol by making use of high pressure approach. A high pressure lab scale plant was developed to conduct CO2 hydrogenation up to 400 bar. High pressure and low temperature were found to be the favourable conditions to excellent catalytic activity. Improved reaction performance towards methanol synthesis and reverse water-gas shift reaction was observed for the Ba and K promoted Cu/Al2O3 catalysts, respe...

  15. State of the art on hydrogen passive auto-catalytic recombiner (european union Parsoar project)

    Energy Technology Data Exchange (ETDEWEB)

    Arnould, F.; Bachellerie, E. [Technicatome, 13 - Aix en Provence (France); Auglaire, M. [Tractebel Energy Engineering, Brussels (Belgium); Boeck, B. de [Association Vincotte Nuclear, Brussels (Belgium); Braillard, O. [CEA Cadarache, 13 - Saint Paul lez Durance (France); Eckardt, B. [Siemens AG, Offenbach am Main (Germany); Ferroni, F. [Electrowatt Engineering Limited, Zurich (Switzerland); Moffett, R. [Atomic Energy Canada Limited, Pinawa (Canada); Van Goethem, G. [European Commission, Brussels (Belgium)

    2001-07-01

    This paper presents an overview of the European Union PARSOAR project, which consists in carrying out a state of the art on hydrogen passive auto-catalytic recombiner (PAR) and a handbook guide for implementing these devices in nuclear power plants. This work is performed in the area ''Operational Safety of Existing Installations'' of the key action ''Nuclear Fission'' of the fifth Euratom Framework Programme (1998-2002). (author)

  16. Ruthenium on rutile catalyst, catalytic system, and method for aqueous phase hydrogenations

    Science.gov (United States)

    Elliot, Douglas C.; Werpy, Todd A.; Wang, Yong; Frye, Jr., John G.

    2001-01-01

    An essentially nickel- and rhenium-free catalyst is described comprising ruthenium on a titania support where the titania is greater than 75% rutile. A catalytic system containing a nickel-free catalyst comprising ruthenium on a titania support where the titania is greater than 75% rutile, and a method using this catalyst in the hydrogenation of an organic compound in the aqueous phase is also described.

  17. State of the art on hydrogen passive auto-catalytic recombiner (european union Parsoar project)

    International Nuclear Information System (INIS)

    This paper presents an overview of the European Union PARSOAR project, which consists in carrying out a state of the art on hydrogen passive auto-catalytic recombiner (PAR) and a handbook guide for implementing these devices in nuclear power plants. This work is performed in the area ''Operational Safety of Existing Installations'' of the key action ''Nuclear Fission'' of the fifth Euratom Framework Programme (1998-2002). (author)

  18. Enhancing charge transfer kinetics by nanoscale catalytic cermet interlayer.

    Science.gov (United States)

    An, Jihwan; Kim, Young-Beom; Gür, Turgut M; Prinz, Fritz B

    2012-12-01

    Enhancing the density of catalytic sites is crucial for improving the performance of energy conversion devices. This work demonstrates the kinetic role of 2 nm thin YSZ/Pt cermet layers on enhancing the oxygen reduction kinetics for low temperature solid oxide fuel cells. Cermet layers were deposited between the porous Pt cathode and the dense YSZ electrolyte wafer using atomic layer deposition (ALD). Not only the catalytic role of the cermet layer itself but the mixing effect in the cermet was explored. For cells with unmixed and fully mixed cermet interlayers, the maximum power density was enhanced by a factor of 1.5 and 1.8 at 400 °C, and by 2.3 and 2.7 at 450 °C, respectively, when compared to control cells with no cermet interlayer. The observed enhancement in cell performance is believed to be due to the increased triple phase boundary (TPB) density in the cermet interlayer. We also believe that the sustained kinetics for the fully mixed cermet layer sample stems from better thermal stability of Pt islands separated by the ALD YSZ matrix, which helped to maintain the high-density TPBs even at elevated temperature. PMID:23151148

  19. Comparative study on the catalytic performance of metal oxide catalysts for decomposition of hydrogen peroxide

    International Nuclear Information System (INIS)

    Commercial CuO and ZnO powders were analyzed for their catalytic activity under different experimental conditions. The mentioned catalysts were characterized by scanning electron microscope, X-ray diffractometery, Fourier transform infrared spectrometry and BET surface area. The decomposition of hydrogen peroxide was studied in the presence of commercial CuO and ZnO under different experimental conditions. Effect of pH on the decomposition reaction was used to evaluate the mechanism of the decomposition reaction. Surface negative sites were responsible for the decomposition of hydrogen peroxide. Rate constants were calculated for the decomposition reactions in pH and temperature ranges of 9-13 and 30-70 degree C, respectively. The observed increase in rate constants with increase in pH and temperature was attributed to the increase in surface negativity of both the solid catalysts. The high surface charge negativity (low PZC) and high surface area of CuO were the dominant factors for the better catalytic activity of the solid as compared to ZnO. The comparative study of these solids clearly demonstrate the higher catalytic activity at a given pH and temperature. Activation energies for the decomposition reaction of hydrogen peroxide on the surfaces of CuO and ZnO estimated from the Arrhenius plots were 57 KJ.mol/sup -1/ and 67 KJ.mol/sup -1/, respectively. (author)

  20. Hydrogen transfer reaction of cyclohexanone with 2-propanol catalysed by CeO2-ZnO materials: Promoting effect of ceria

    Indian Academy of Sciences (India)

    Braja Gopal Mishra; G Ranga Rao; B Poongodi

    2003-10-01

    Ce-Zn-O mixed oxides were prepared by amorphous citrate process and decomposition of the corresponding acetate precursors. The resulting materials were characterised by TGA, XRD, UV-Vis-DRS, EPR, SEM and surface area measurements. XRD and DRS results indicated fine dispersion of the ceria component in the ZnO matrix. EPR results clearly indicate the presence of oxygen vacancy and defect centres in the composite oxide. Addition of CeO2 to ZnO produced mixed oxides of high surface area compared to the pure ZnO. Hydrogen transfer reaction was carried out on these catalytic materials to investigate the effect of rare earth oxide on the activity of ZnO. Addition of ceria into zinc oxide was found to increase the catalytic activity for hydrogen transfer reaction. The catalytic activity also depended on the method of preparation. Citrate process results in uniformly dispersed mixed oxide with higher catalytic activity.

  1. Magnetically Recoverable Supported Ruthenium Catalyst for Hydrogenation of Alkynes and Transfer Hydrogenation of Carbonyl Compounds

    Science.gov (United States)

    A ruthenium (Ru) catalyst supported on magnetic nanoparticles (NiFe2O4) has been successfully synthesized and used for hydrogenation of alkynes at room temperature as well as transfer hydrogenation of a number of carbonyl compounds under microwave irradiation conditions. The cata...

  2. A bimodal catalytic membrane having a hydrogen-permselective silica layer on a bimodal catalytic support: Preparation and application to the steam reforming of methane

    OpenAIRE

    Tsuru, Toshinori; Shintani, Hiroaki; Yoshioka, Tomohisa; Asaeda, Masashi

    2006-01-01

    The steam reforming of methane for hydrogen production was experimentally investigated using catalytic membrane reactors, consisting of a microporous silica top layer, for the selective permeation of hydrogen, and an α-alumina support layer, for catalytic reaction of the steam reforming of methane. An α-alumina support layer with a bimodal structure, which was proposed for the enhanced dispersion of Ni catalysts, was prepared by impregnating γ-Al2O3 inside α-Al2O3 microfiltration membranes (1...

  3. Intermolecular Hydrogen Transfer in Isobutane Hydrate

    Directory of Open Access Journals (Sweden)

    Takeshi Sugahara

    2012-05-01

    Full Text Available Electron spin resonance (ESR spectra of butyl radicals induced with γ-ray irradiation in the simple isobutane (2-methylpropane hydrate (prepared with deuterated water were investigated. Isothermal annealing results of the γ-ray-irradiated isobutane hydrate reveal that the isobutyl radical in a large cage withdraws a hydrogen atom from the isobutane molecule through shared hexagonal-faces of adjacent large cages. During this “hydrogen picking” process, the isobutyl radical is apparently transformed into a tert-butyl radical, while the sum of isobutyl and tert-butyl radicals remains constant. The apparent transformation from isobutyl to tert-butyl radicals is an irreversible first-order reaction and the activation energy was estimated to be 35 ± 3 kJ/mol, which was in agreement with the activation energy (39 ± 5 kJ/mol of hydrogen picking in the γ-ray-irradiated propane hydrate with deuterated water.

  4. Catalytic heat exchangers for small-scale production of hydrogen - feasibility study

    Energy Technology Data Exchange (ETDEWEB)

    Silversand, F. [Catator AB, Lund (Sweden)

    2002-02-01

    A feasibility study concerning heat-exchanger reactors in small-scale production of hydrogen has been performed on the request of Svenskt Gastekniskt Center AB and SWEP International AB. The basic idea is to implement different catalysts into brazed plate-type heat exchangers. This can be achieved by installing catalytic cylinders in the inlet-and outlet ports of the heat exchangers or through treatment of the plates to render them catalytically active. It is also possible to sandwich catalytically active wire meshes between the plates. Experiments concerning steam reforming of methanol and methane have been performed in a micro-reactor to gather kinetic data for modelling purposes. Performance calculations concerning heat exchanger reactors have then been conducted with Catator's generic simulation code for catalytic reactors (CatalystExplorer). The simulations clearly demonstrate the technical performance of these reactors. Indeed, the production rate of hydrogen is expected to be about 10 nm{sup 3}/h per litre of heat exchanger. The corresponding value for a conventional steam-reforming unit is about 1 nm{sup 3}/h or less per litre of reactor volume. Also, the compactness and the high degree of integration together with the possibilities of mass production will give an attractive cost for such units. Depending on the demands concerning the purity of the hydrogen it is possible to add secondary catalytic steps like water-gas shifters, methanation and selective oxidation, into a one-train unit, i.e. to design an all-inclusive design. Such reactors can be used for the supply of hydrogen to fuel cells. The production cost for hydrogen can be cut by 60 - 70% through the utilisation of heat exchanger reactors instead of conventional electrolysis. This result is primarily a result of the high price for electricity compared to the feed stock prices in steam reforming. It is important to verify the performance calculations and the simulation results through

  5. Muon transfer from hot muonic hydrogen atoms to neon

    International Nuclear Information System (INIS)

    A negative muon beam has been directed on adjacent solid layers of hydrogen and neon. Three targets differing by their deuterium concentration were investigated. Muonic hydrogen atoms can drift to the neon layer where the muon is immediately transferred. The time structure of the muonic neon X-rays follows the exponential law with a disappearance rate corresponding to the one of μ-p atoms in each target. The rates λppμ and λpd can be extracted

  6. Study of reactive transfer of hydrogen within intact clayrock

    OpenAIRE

    Didier, Mathilde

    2012-01-01

    Hydrogen gas will be produced by anaerobic corrosion of radioactive waste containers in the geological repository. This gas could affect the geological layer (Callovo-Oxfordian) stability, first due to its reductive capacity and then also due to its continuous production for about 100,000 years. The local pressure increase could affect the properties of hydro-gaseous dynamic of hydrogen transfers. The reductive capacity of H2 could change the redox properties of the Callovo-Oxfordian and the ...

  7. Catalytic activity of Ni3S2 and effects of reactor wall in hydrogen production from water with hydrogen sulphide as a reducer under hydrothermal conditions

    International Nuclear Information System (INIS)

    Catalytic activity of Ni3S2 and the effects of reactor wall in the hydrogen production from water were investigated under hydrothermal conditions using hydrogen sulphide (H2S) as a reductant. It was found that Ni3S2 catalysed the hydrogen production from water and may act as a semi-conductor catalyst. In the case of addition of Ni3S2, the time required to achieve the maximum hydrogen yield significantly decreased and the maximum hydrogen yield increased. These results suggest that the Ni3S2 formed as a corrosion product of the reactor wall when using the Hastelloy C-276 lined reactor should play a catalytic role in the hydrogen production. These results could facilitate studies for the synthesis of highly active catalysts for the production of hydrogen under mild conditions

  8. Catalytic process for control of NO.sub.x emissions using hydrogen

    Science.gov (United States)

    Sobolevskiy, Anatoly; Rossin, Joseph A.; Knapke, Michael J.

    2010-05-18

    A selective catalytic reduction process with a palladium catalyst for reducing NOx in a gas, using hydrogen as a reducing agent. A zirconium sulfate (ZrO.sub.2)SO.sub.4 catalyst support material with about 0.01-2.0 wt. % Pd is applied to a catalytic bed positioned in a flow of exhaust gas at about 70-200.degree. C. The support material may be (ZrO.sub.2--SiO.sub.2)SO.sub.4. H.sub.2O and hydrogen may be injected into the exhaust gas upstream of the catalyst to a concentration of about 15-23 vol. % H.sub.2O and a molar ratio for H.sub.2/NO.sub.x in the range of 10-100. A hydrogen-containing fuel may be synthesized in an Integrated Gasification Combined Cycle power plant for combustion in a gas turbine to produce the exhaust gas flow. A portion of the fuel may be diverted for the hydrogen injection.

  9. Substrate-mediated enhanced activity of Ru nanoparticles in catalytic hydrogenation of benzene

    KAUST Repository

    Liu, Xin

    2012-01-01

    The impact of carbon substrate-Ru nanoparticle interactions on benzene and hydrogen adsorption that is directly related to the performance in catalytic hydrogenation of benzene has been investigated by first-principles based calculations. The stability of Ru 13 nanoparticles is enhanced by the defective graphene substrate due to the hybridization between the dsp states of the Ru 13 particle with the sp 2 dangling bonds at the defect sites. The local curvature formed at the interface will also raise the Ru atomic diffusion barrier, and prohibit the particle sintering. The strong interfacial interaction results in the shift of averaged d-band center of the deposited Ru nanoparticle, from -1.41 eV for a freestanding Ru 13 particle, to -1.17 eV for the Ru/Graphene composites, and to -1.54 eV on mesocellular foam carbon. Accordingly, the adsorption energies of benzene are increased from -2.53 eV for the Ru/mesocellular foam carbon composites, to -2.62 eV on freestanding Ru 13 particles, to -2.74 eV on Ru/graphene composites. A similar change in hydrogen adsorption is also observed, and all these can be correlated to the shift of the d-band center of the nanoparticle. Thus, Ru nanoparticles graphene composites are expected to exhibit both high stability and superior catalytic performance in hydrogenation of arenes. © 2012 The Royal Society of Chemistry.

  10. Reversible Hydrogen Storage Characteristics of Catalytically Enhanced Ca(Li)-nMg-B-N-H System

    Science.gov (United States)

    Srinivasan, Sesha; Emre Demircak, Dervis; Sharma, Prakash; Yogi, Goswami; Stefanakos, Elias

    2013-04-01

    The aim of the present investigation is to study the synergistic effects of multi-walled carbon nanotubes, Nb2O5 and other catalysts for reversible hydrogen storage characteristics of Ca(Li)-nMg-B-N-H systems. Multinary hydride using light weight, high capacity hydride compounds such as Ca(BH4)2, LiBH4, LiNH2, nanoMgH2 in 3:1:8:4 composition was synthesized using high energy planetary milling under Ar/H2 ambient. Various nano additives and bi-metallic catalysts were added in a very small concentration with the host hydride (Ca)Li-nMg-B-N-H. The TGA and DSC results demonstrated that the catalytically enhanced Ca(Li)-nMg-B-N-H with hydrogen release at lower temperatures when compared to the pristine systems such as either Ca-Li-B-H or Ca-Li-Mg-B-H. Analyses of metrological characterization using XRD, SEM and have revealed the effectiveness and the role of the catalytic nanoparticles and their enhanced reversible hydrogen storage behavior on the host hydride matrix. The mass spectrometric investigations employing RGA on these nanocrystalline, multi-component hydride systems exhibit the release of hydrogen in major proportion (˜80-90%) as compared to previously attributed ammonia.

  11. Production of hydrogen from biomass by catalytic steam reforming of fast pyrolysis oil

    Energy Technology Data Exchange (ETDEWEB)

    Czernik, S.; Wang, D.; Chornet, E. [National Renewable Energy Lab., Golden, CO (United States). Center for Renewable Chemical Technologies and Materials

    1998-08-01

    Hydrogen is the prototype of the environmentally cleanest fuel of interest for power generation using fuel cells and for transportation. The thermochemical conversion of biomass to hydrogen can be carried out through two distinct strategies: (a) gasification followed by water-gas shift conversion, and (b) catalytic steam reforming of specific fractions derived from fast pyrolysis and aqueous/steam processes of biomass. This paper presents the latter route that begins with fast pyrolysis of biomass to produce bio-oil. This oil (as a whole or its selected fractions) can be converted to hydrogen via catalytic steam reforming followed by a water-gas shift conversion step. Such a process has been demonstrated at the bench scale using model compounds, poplar oil aqueous fraction, and the whole pyrolysis oil with commercial Ni-based steam reforming catalysts. Hydrogen yields as high as 85% have been obtained. Catalyst initial activity can be recovered through regeneration cycles by steam or CO{sub 2} gasification of carbonaceous deposits.

  12. Catalytic hydrogenation of naphthalene through water gas shift reaction in supercritical water

    Energy Technology Data Exchange (ETDEWEB)

    Okazaki, S.; Kurosawa, S.; Adschiri, T.; Arai, K. [Tohoku University, Sendai (Japan). Dept. of Chemical Engineering

    1998-07-01

    The catalytic hydrogenation of naphthalene through water-gas shift reaction in supercritical water (SCW) was studied with batch experiments. A comparative study of catalytic hydrogenation of naphthalene with NiMo/Al{sub 2}O{sub 3} at 673 K and water density of 0.3 g/cm{sup 3} (30 MPa) was conducted in various atmospheres. Higher conversion of naphthalene to tetralin was obtained in CO-SCW, and H{sub 2}-CO{sub 2}-SCW than in H{sub 2}-SCW. The results clearly indicate that the water-gas shift reaction in SCW produces species which can hydrogenate naphthalene more effectively than H{sub 2} gas in SCW. The effect of water density (0.1-0.5 g/cm{sup 3}) on the hydrogenation in H{sub 2}-SCW and in CO-SCW was also studied. In H{sub 2}-SCW, naphthalene conversion gradually decreased with increasing water density. In CO-SCW, naphthalene conversion first increased and then gradually decreased with increasing water density. 8 refs., 2 figs.

  13. Liquid-Phase Catalytic Hydrogenation of Furfural in Variable Solvent Media

    Institute of Scientific and Technical Information of China (English)

    夏淑倩; 李阳; 商巧燕; 张成武; 马沛生

    2016-01-01

    Water is the most abundant compound inherently existing in bio-oils. Thus understanding the role of water within bio-oils upgrading process is essential for future engineering scale-up design. In this study, furfural was chosen as bio-oils model compound, and the catalytic hydrogenation of furfural over commercial 5%, Ru/C catalyst was firstly investigated in a series of gradient variable water/ethanol mixture solvents. Water had a signifi-cant effect on the distribution of product yields. The dominant reaction pathways varied with the water contents in the water/ethanol mixture solvents. Typically, when ethanol was used as the solvent, the main products were ob-tained by the hydrogenation of carbonyl group or furan ring. When pure water was used as the solvent, the rear-rangement reaction of furfural to cyclopentanone should be selectively promoted theoretically. However, serious polymerization and resinification were observed herein in catalytic hydrogenation system of pure water. The cata-lyst surface was modified by the water-insoluble polymers, and consequently, a relative low yield of cyclopenta-none was obtained. A plausible multiple competitive reaction mechanism between polymerization reaction and the hydrogenation of furfural was suggested in this study. Characterizations(TG,FT-IR,SEM)were employed to analyze and explain our experiments.

  14. Hydrogen production from palm kernel shell via integrated catalytic adsorption (ICA) steam gasification

    International Nuclear Information System (INIS)

    Highlights: • The paper presents integrated catalytic adsorption (ICA) steam gasification for H2 yield. • Effects of adsorbent to biomass, biomass particle size and fluidization velocity on H2 yield are examined. • The present study produces higher H2 yield as compared to that obtained in literatures. • The ICA provides enhancement of H2 yield as compared to independent catalytic and CO2 adsorption gasification systems. - Abstract: The present study investigates the integrated catalytic adsorption (ICA) steam gasification of palm kernel shell for hydrogen production in a pilot scale atmospheric fluidized bed gasifier. The biomass steam gasification is performed in the presence of an adsorbent and a catalyst in the system. The effect of adsorbent to biomass (A/B) ratio (0.5–1.5 wt/wt), fluidization velocity (0.15–0.26 m/s) and biomass particle size (0.355–2.0 mm) are studied at temperature of 675 °C, steam to biomass (S/B) ratio of 2.0 (wt/wt) and biomass to catalyst ratio of 0.1 (wt/wt). Hydrogen composition and yield, total gas yield, and lower product gas heating values (LHVgas) increases with increasing A/B ratio, while particle size has no significant effect on hydrogen composition and yield, total gas and char yield, gasification and carbon conversion efficiency. However, gas heating values increased with increasing biomass particle size which is due to presence of high methane content in product gas. Meanwhile, medium fluidization velocity of 0.21 m/s favoured hydrogen composition and yield. The results showed that the maximum hydrogen composition and yield of 84.62 vol% and 91.11 g H2/kg biomass are observed at A/B ratio of 1.5, S/B ratio of 2.0, catalyst to biomass ratio of 0.1 and temperature of 675 °C. The product gas heating values are observed in the range of 10.92–17.02 MJ/N m3. Gasification and carbon conversion efficiency are observed in the range of 25.66–42.95% and 20.61–41.95%, respectively. These lower efficiencies are due

  15. 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

  16. Catalytic hydrogenation of aromatic hydrocarbons. Stereochemical definition of the catalytic cycle for eta3-C3H5Co(P(OCH3)3)3

    International Nuclear Information System (INIS)

    The eta3-C3H5Co(P(OCH3)3)3-catalyzed hydrogenations with D2 of a series of unsaturated organic molecules, including cyclohexenes, cyclohexadienes, and arenes, have been investigated. Complete cis stereoselectivity was observed in the addition of deuterium to the unsaturated ring systems. When alkyl-substituted arenes were reduced with D2, the hydrogen atoms in the alkyl chains underwent H-D exchange as long as each successive carbon atom in the chain possessed at least one hydrogen atom. Hence, extensive H-D exchange occurred in n-alkyl side chains while the tert-butyl side chain was deuterium free. When alkyl-substituted arenes were hydrogenated in the presence of olefins such as 1-hexene, a variety of isomeric alkylcyclohexenes and alkenylcyclohexanes were observed. The relative concentrations of these isomeric species provided information about the relative stabilities of the (olefin)cobalt species in the catalytic cycle. Further mechanistic information was obtained from other competitive reactions, i.e., hydrogenation reactions involving equimolar quantities of two different unsaturated molecules. The proposed initiation steps of the catalytic cycle have been revised on the basis of a study of eta3-C8H13Co(P(OCH3)3)3 as a catalyst precursor. The cyclooctenyl-cobalt bond was cleaved by hydrogen early in the reaction, leaving the highly coordinately unsaturated hydride, HCo(P(OCH3)3)2, which is probably the true catalytic species

  17. Contribution to the study of catalytic hydrogen-deuterium exchange between hydrogen and hydrocarbons

    International Nuclear Information System (INIS)

    The hydrogen-deuterium exchange between molecular hydrogen and hydrocarbons over a platinum and charcoal catalyst was studied in a static system. The change in isotopic composition of molecular hydrogen was followed by a thermal conductivity method. Cyclo-pentane and cyclohexane were chosen because of their stability. A reversible inactivation of the catalyst was observed with both hydrocarbons. The reasons for this inactivation are unknown but it was shown that reactivation led to satisfactory reproducibility. A kinetic study was done with cyclohexane in the range 30 to 160 deg. C, and 40 to 360 mm for the pressure of hydrogen, and 10 to 70 mm for the pressure of cyclohexane. The order of the reaction with respect to cyclohexane pressure is always close to zero; the order with respect to that of hydrogen is 0.5 above 100 deg. C. It decreases with increasing temperature and becomes negative (-0.5 at 30 deg. C), characterizing an inhibition by hydrogen. At the same time, the apparent activation energy goes from 6 to 13 kcal/mole. (author)

  18. Asymmetric Transfer Hydrogenation of ω -Bromo Acetophenones in Aqueous Media

    Institute of Scientific and Technical Information of China (English)

    Wang Fei; Liu Hui; Cui Xin; Cun Linfeng; Zhu Jin; Deng Jingen; Jiang Yaozhong

    2004-01-01

    Optical active ω-bromophenylethanols are useful building blocks for synthesis of various pharmaceuticals such as α 1-, β 2-, and β 3- adrenergic receptor agonists, which are always obtained though a biotransformative pathway and using boron reagent with rigorous conditions [1]. To our knowledge, the metal-catalysed transfer hydrogenation is seldom applied in this reaction. Recently we have developed a water-soluble chiral Ru-complex and applied successfully in transfer hydrogenation of ω-bromo acetophenones in aqueous media [2], which can not be performed in homogeneous system with HCOOH/NEt3 as hydrogen donor[3] .In this paper, we will report that asymmetric transfer hydrogenation of ω-bromo acetophenones was successfully performed in aqueous media by employing hydrophobic Rh-amido complex (TsDPEN-Rh) as catalyst and HCOONa as hydrogen donor. Moreover, marked increasing of activity and high enantioselectivity (up to 98%) of ω-bromo acetophenone 1a was found in the presence of different micelles or vesicles. This method was also applied successfully in preparation of the important chiral medicinal intermediates, such as the precursor of salbutamol, 2b and fermoterol, 2c with high enantioselectivity.

  19. Effects of Oxygen Transfer Limitation and Kinetic Control on Biomimetic Catalytic Oxidation of Toluene

    Institute of Scientific and Technical Information of China (English)

    罗伟平; 刘大为; 孙俊; 邓伟; 盛文兵; 刘强; 郭灿城

    2014-01-01

    Under oxygen transfer limitation and kinetic control, liquid-phase catalytic oxidation of toluene over metalloporphyrin was studied. An improved technique of measuring dissolved oxygen levels for gas-liquid reaction at the elevated temperature and pressure was used to take the sequential data in the oxidation of toluene catalyzed by metalloporphyrin. By this technique the corresponding control step of toluene oxidation could be obtained by varying reaction conditions. When the partial pressure of oxygen in the feed is lower than or equal to 0.070 MPa at 463 K, the oxidation of toluene would be controlled by oxygen transfer, otherwise the reaction would be controlled by kinetics. The effects of both oxygen transfer and kinetic control on the toluene conversion and the selectivity of benzaldehyde and benzyl alcohol in biomimetic catalytic oxidation of toluene were systematically investigated. Three conclusions have been made from the experimental results. Firstly, under the oxygen transfer limitation the toluene conversion is lower than that under kinetic control at the same oxidation conditions. Secondly, under the oxygen transfer limitation the total selectivity of benzaldehyde and benzyl alcohol is lower than that under kinetic control with the same conversion of toluene. Finally, under the kinetics control the oxidation rate of toluene is zero-order with respect to oxygen. The experimental results are identical with the biomimetic catalytic mechanism of toluene oxidation over metalloporphyrins.

  20. PREPARATION AND CATALYTIC BEHAVIOUR OF POLYMER-BOUND METALLOPORPHYRIN IN HYDROGENATION OF OLEFIN

    Institute of Scientific and Technical Information of China (English)

    1998-01-01

    The meso-tetraarylporphyrin has been anchored to styrene-divinylbenzene copolymers by reaction of meso-tetra(4-hydroxylphenyl) porphyrin with chloromethylated resin under mild condition. A number of polymer transition metal complexes have been prepared with the polymer ligand and metal salts. The polymeric ligand and its complexes have been characterized by electronic spectra, and vibrational spectra. Cyclohexene can be hydrogenated with the polymeric porphyrin palladium complex(P-THPPPd) as catalyst, and its catalytic activity was influenced by the polarity of solvents, the contents of water in ethanol or reaction temperature. However, its catalytic activity was lower for nitro groups, carbonyl groups and olefins with steric hindrance substituents, and showed no activity for aromatic rings under these conditions.

  1. Catalytic hydrodechlorination of chloroaromatic gas streams promoted by Pd and Ni: The role of hydrogen spillover

    Energy Technology Data Exchange (ETDEWEB)

    Amorim, Claudia [Department of Chemical and Materials Engineering, University of Kentucky, Lexington, KY (United States); Keane, Mark A., E-mail: M.A.Keane@hw.ac.uk [Chemical Engineering, School of Engineering and Physical Sciences, Heriot-Watt University, Edinburgh EH14 4AS, Scotland (United Kingdom)

    2012-04-15

    Highlights: Black-Right-Pointing-Pointer Effective application of catalytic hydrodechlorination in the treatment of toxic chloroaromatic gas streams. Black-Right-Pointing-Pointer Demonstration of spillover hydrogen associated with Pd/Al{sub 2}O{sub 3}, Ni/Al{sub 2}O{sub 3}, Pd + Al{sub 2}O{sub 3} and Ni + Al{sub 2}O{sub 3}. Black-Right-Pointing-Pointer Combination of Al{sub 2}O{sub 3} with Pd, Ni, Pd/Al{sub 2}O{sub 3} and Ni/Al{sub 2}O{sub 3} enhances spillover content. Black-Right-Pointing-Pointer Spillover hydrogen contributes to enhanced hydrodechlorination performance. - Abstract: Catalytic hydrodechlorination (HDC) is an effective means of detoxifying chlorinated waste. Involvement of spillover hydrogen is examined in gas phase dechlorination of chlorobenzene (CB) and 1,3-dichlorobenzene (1,3-DCB) over Pd and Ni. The catalytic action of single component Pd and Ni, Pd/Al{sub 2}O{sub 3}, Ni/Al{sub 2}O{sub 3} and physical mixtures with Al{sub 2}O{sub 3} has been considered. Catalyst activation is characterized in terms of temperature programmed reduction, the supported nano-scale metal phase by transmission electron microscopy and hydrogen/surface interactions by chemisorption/temperature programmed desorption. Pd/Al{sub 2}O{sub 3} generated significantly greater amounts of spillover hydrogen (by a factor of over 40) compared with Ni/Al{sub 2}O{sub 3}. Hydrogen spillover on Pd/Al{sub 2}O{sub 3} far exceeded the chemisorbed component, whereas chemisorbed and spillover content was equivalent for Ni/Al{sub 2}O{sub 3}. Inclusion of Al{sub 2}O{sub 3} with Ni and Ni/Al{sub 2}O{sub 3} increased spillover with an associated increase in specific HDC rate (up to a factor of 10) and enhanced selectivity to benzene from 1,3-DCB. HDC rate delivered by Pd and Pd/Al{sub 2}O{sub 3} was largely unaffected by the addition of Al{sub 2}O{sub 3}. This can be attributed to the higher intrinsic HDC performance of Pd that results in appreciable HDC activity under conditions where Ni

  2. An investigation of turbulent catalytically stabilized channel flow combustion of lean hydrogen - air mixtures

    Energy Technology Data Exchange (ETDEWEB)

    Mantzaras, I.; Benz, P.; Schaeren, R.; Bombach, R. [Paul Scherrer Inst. (PSI), Villigen (Switzerland)

    1999-08-01

    The catalytically stabilised thermal combustion (CST) of lean hydrogen-air mixtures was investigated numerically in a turbulent channel flow configuration using a two-dimensional elliptic model with detailed heterogeneous and homogeneous chemical reactions. Comparison between turbulent and laminar cases having the same incoming mean properties shows that turbulence inhibits homogeneous ignition due to increased heat transport away from the near-wall layer. The peak root-mean-square temperature and species fluctuations are always located outside the extent of the homogeneous reaction zone indicating that thermochemical fluctuations have no significant influence on gaseous combustion. (author) 4 figs., 6 refs.

  3. Simple and rapid hydrogenation of p-nitrophenol with aqueous formic acid in catalytic flow reactors

    OpenAIRE

    Javaid, Rahat; Kawasaki, Shin-ichiro; Suzuki, Akira; Suzuki, Toshishige M

    2013-01-01

    The inner surface of a metallic tube (i.d. 0.5 mm) was coated with a palladium (Pd)-based thin metallic layer by flow electroless plating. Simultaneous plating of Pd and silver (Ag) from their electroless-plating solution produced a mixed distributed bimetallic layer. Preferential acid leaching of Ag from the Pd–Ag layer produced a porous Pd surface. Hydrogenation of p-nitrophenol was examined in the presence of formic acid simply by passing the reaction solution through the catalytic tubular...

  4. 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

  5. Hydrogen Production From Crude Bio-oil and Biomass Char by Electrochemical Catalytic Reforming

    Institute of Scientific and Technical Information of China (English)

    Xing-long Li; Shen Ning; Li-xia Yuan; Quan-xin Li

    2011-01-01

    We reports an efficient approach for production of hydrogen from crude bio-oil and biomass char in the dual fixed-bed system by using the electrochemical catalytic reforming method.The maximal absolute hydrogen yield reached 110.9 g H2/kg dry biomass.The product gas was a mixed gas containing 72%H2,26%CO2,1.9%CO,and a trace amount of CH4.It was observed that adding biomass char (a by-product of pyrolysis of biomass) could remarkably increase the absolute H2 yield (about 20%-50%).The higher reforming temperature could enhance the steam reforming reaction of organic compounds in crude bio-oil and the reaction of CO and H2O.In addition,the CuZn-Al2O3 catalyst in the water-gas shift bed could also increase the absolute H2 yield via shifting CO to CO2.

  6. Hydrogen production by Thermo Catalytic Decomposition of Natural Gas: Ni-based catalysts

    International Nuclear Information System (INIS)

    Thermo Catalytic Decomposition of methane using Ni and Ni-Cu catalyst is studied. The conventional co-precipitation method is compared versus an easier preparation method based on the fusing of the metallic nitrates. The role of copper has also been analyzed. TCD has been carried out in a bench scale fixed bed and a semi-pilot scale fluidized bed. Catalysts prepared by both methods shown similar behaviour. Introduction of copper in the catalyst promoted NiO reduction which prevented hydrogen from CO contamination. Fluid-dynamic studies have shown that TCD can be carried out in a fluidized bed reactor without reactor clogging provided that a methane velocity of two times the minimum fluidization velocity is used. This high spatial velocity resulted in a reduction of methane conversion. So the optimum gas velocity should be chosen in terms of hydrogen production rates and fluidization quality. (authors)

  7. Development of a para-orthohydrogen catalytic converter for a solid hydrogen cooler

    Science.gov (United States)

    Nast, T. C.; Hsu, I. C.

    1984-01-01

    Design features of a tested catalytic converter for altering vented cryogenic parahydrogen used as a coolant on spacecraft into a para-ortho equilibrium for channeling to other cooling functions are described. The hydrogen is expected to be stored in either liquid or solid form. A high surface area Ni-on-Si catalyst was selected for tests at an operating pressure of 2 torr at a ratio of 1000 gr catalyst for a gr/sec hydrogen flow. Cylindrical and radial flow geometries were tried and measurements centered on the converter efficiencies at different operating temperatures when the converter was placed in the vent line of the H2 cooler. Efficiencies ranging from 10-100 percent were obtained for varying flow rates. Further testing is necessary to characterize the converter performance under a wider range of operating temperatures and environments.

  8. Biomass-to-hydrogen via fast pyrolysis and catalytic steam reforming

    Energy Technology Data Exchange (ETDEWEB)

    Chornet, E.; Wang, D.; Czernik, S. [National Renewable Energy Lab., Golden, CO (United States)] [and others

    1996-10-01

    Pyrolysis of lignocellulosic biomass and reforming the pyroligneous oils is being studied as a strategy for producing hydrogen. Novel technologies for the rapid pyrolysis of biomass have been developed in the past decade. They provide compact and efficient systems to transform biomass into vapors that are condensed to oils, with yields as high as 75-80 wt.% of the anhydrous biomass. This {open_quotes}bio-oil{close_quotes} is a mixture of aldehydes, alcohols, acids, oligomers from the constitutive carbohydrates and lignin, and some water derived from the dehydration reactions. Hydrogen can be produced by reforming the bio-oil or its fractions with steam. A process of this nature has the potential to be cost competitive with conventional means of producing hydrogen. The reforming facility can be designed to handle alternate feedstocks, such as natural gas and naphtha, if necessary. Thermodynamic modeling of the major constituents of the bio-oil has shown that reforming is possible within a wide range of temperatures and steam-to-carbon ratios. Existing catalytic data on the reforming of oxygenates have been studied to guide catalyst selection. Tests performed on a microreactor interfaced with a molecular beam mass spectrometer showed that, by proper selection of the process variables: temperature, steam-to-carbon ratio, gas hourly space velocity, and contact time, almost total conversion of carbon in the feed to CO and CO{sub 2} could be obtained. These tests also provided possible reaction mechanisms where thermal cracking competes with catalytic processes. Bench-scale, fixed bed reactor tests demonstrated high hydrogen yields from model compounds and carbohydrate-derived pyrolysis oil fractions. Reforming bio-oil or its fractions required proper dispersion of the liquid to avoid vapor-phase carbonization of the feed in the inlet to the reactor. A special spraying nozzle injector was designed and successfully tested with an aqueous fraction of bio-oil.

  9. Highly versatile catalytic hydrogenation of carboxylic and carbonic acid derivatives using a Ru-triphos complex: molecular control over selectivity and substrate scope.

    Science.gov (United States)

    vom Stein, Thorsten; Meuresch, Markus; Limper, Dominik; Schmitz, Marc; Hölscher, Markus; Coetzee, Jacorien; Cole-Hamilton, David J; Klankermayer, Jürgen; Leitner, Walter

    2014-09-24

    The complex [Ru(Triphos)(TMM)] (Triphos = 1,1,1-tris(diphenylphosphinomethyl)ethane, TMM = trimethylene methane) provides an efficient catalytic system for the hydrogenation of a broad range of challenging functionalities encompassing carboxylic esters, amides, carboxylic acids, carbonates, and urea derivatives. The key control factor for this unique substrate scope results from selective activation to generate either the neutral species [Ru(Triphos)(Solvent)H2] or the cationic intermediate [Ru(Triphos)(Solvent)(H)(H2)](+) in the presence of an acid additive. Multinuclear NMR spectroscopic studies demonstrated together with DFT investigations that the neutral species generally provides lower energy pathways for the multistep reduction cascades comprising hydrogen transfer to C═O groups and C-O bond cleavage. Carboxylic esters, lactones, anhydrides, secondary amides, and carboxylic acids were hydrogenated in good to excellent yields under these conditions. The formation of the catalytically inactive complexes [Ru(Triphos)(CO)H2] and [Ru(Triphos)(μ-H)]2 was identified as major deactivation pathways. The former complex results from substrate-dependent decarbonylation and constitutes a major limitation for the substrate scope under the neutral conditions. The deactivation via the carbonyl complex can be suppressed by addition of catalytic amounts of acids comprising non-coordinating anions such as HNTf2 (bis(trifluoromethane)sulfonimide). Although the corresponding cationic cycle shows higher overall barriers of activation, it provides a powerful hydrogenation pathway at elevated temperatures, enabling the selective reduction of primary amides, carbonates, and ureas in high yields. Thus, the complex [Ru(Triphos)(TMM)] provides a unique platform for the rational selection of reaction conditions for the selective hydrogenation of challenging functional groups and opens novel synthetic pathways for the utilization of renewable carbon sources. PMID:25208046

  10. Stereo-Specific Hydrogen Exchange Accompanying Catalytic Hydrogenation of Methyl β, β-Dimethylacrylate

    International Nuclear Information System (INIS)

    During platinum or palladium-catalysed hydrogenation in which, in solution, methyl β, β-dimethylacrylate is converted into the corresponding ester of isovaleric acid by the equation CH3CH3>C = CH-COOCH3 H2, cat. sol. --> CH3CH3>C = CH-CH2-COOCH3' an isotopic exchange of hydrogen between the gas and the solvent on the one hand and the substrate on the other is superposed upon the process of saturation of the double bond. This was studied by carrying out, at 20°C, hydrogenations which were interrupted after saturation of half the starting product and by employing D2 or esters deuterated either totally or at specific positions, different positions being used from experiment to experiment. The isotopic composition of the hydrogen at each of the positions of the molecules, both saturated and non-saturated, was determined, after separation of the molecules by chromatography in the gaseous phase, by combined mass spectrometry and nuclear magnetic resonance. A separate study was made of behaviour in respect of exchange of substrate in the non-saturated and saturated state, in the absence of hydrogen or the catalyst or both. Among the factors examined were, in particular, the effects of the solvent and the catalyst - which were very pronounced - on all the phenomena observed. These can be summarized as follows, (a) Molecules of the substrate no longer exchange once they are saturated, (b) With non-saturated molecules, restricted exchange takes place in which only the β-methyls are involved. This exchange is symmetric in the presence of rhodium and palladium, and stereo-specific in the presence of platinum - on an average 2.2 times greater in the cis-group than in the trans-group. This fact in the latter case excludes the hypothesis of double bond migration from the α-β position to the β-γ position as an exchange mechanism; which is confirmed by the absence of exchange at the exposition, (c) All the isotopic varieties from -d0 to -d6 or -d8 are present in the

  11. Biomass to hydrogen-rich syngas via catalytic steam gasification of bio-oil/biochar slurry.

    Science.gov (United States)

    Chen, Guanyi; Yao, Jingang; Liu, Jing; Yan, Beibei; Shan, Rui

    2015-12-01

    The catalytic steam gasification of bio-oil/biochar slurry (bioslurry) for hydrogen-rich syngas production was investigated in a fixed-bed reactor using LaXFeO3 (X=Ce, Mg, K) perovskite-type catalysts. The effects of elemental substitution in LaFeO3, temperature, water to carbon molar ratio (WCMR) and bioslurry weight hourly space velocity (WbHSV) were examined. The results showed that La0.8Ce0.2FeO3 gave the best performance among the prepared catalysts and had better catalytic activity and stability than the commercial 14 wt.% Ni/Al2O3. The deactivation caused by carbon deposition and sintering was significantly depressed in the case of La0.8Ce0.2FeO3 catalyst. Both higher temperature and lower WbHSV contributed to more H2 yield. The optimal WCMR was found to be 2, and excessive introducing of steam reduced hydrogen yield. The La0.8Ce0.2FeO3 catalyst gave a maximum H2 yield of 82.01% with carbon conversion of 65.57% under the optimum operating conditions (temperature=800°C, WCMR=2 and WbHSV=15.36h(-1)). PMID:26378962

  12. A resource recycling technique of hydrogen production from the catalytic degradation of organics in wastewater

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    A resource recycling technique of hydrogen production from the catalytic degradation of organics in wastewater by aqueous phase reforming (APR) has been proposed. It is worthy of noting that this technique may be a potential way for the purification of refractory and highly toxic organics in water for hydrogen production. Hazardous organics (such as phenol, aniline, nitrobenzene, tetrahydrofuran (THF), toluene, N,N-dimethylformamide (DMF) and cyclohexanol) in water could be completely de-graded into H2 and CO2 with high selectivity over Raney Ni, and Sn-modified Raney Ni (Sn-Raney-Ni) or Pd/C catalyst under mild conditions. The experimental results operated in tubular and autoclave reactors, indicated that the degradation degree of organics and H2 selectivity could reach 100% under the optimal reaction conditions. The Sn-Raney-Ni (Sn/Ni=0.06) and Pd/C catalysts show better catalytic performances than the Raney Ni catalyst for the degradation of organics in water into H2 and CO2 by the aqueous phase reforming process.

  13. Nitrene Metathesis and Catalytic Nitrene Transfer Promoted by Niobium Bis(imido) Complexes.

    Science.gov (United States)

    Kriegel, Benjamin M; Bergman, Robert G; Arnold, John

    2016-01-13

    We report a metathesis reaction in which a nitrene fragment from an isocyanide ligand is exchanged with a nitrene fragment of an imido ligand in a series of niobium bis(imido) complexes. One of these bis(imido) complexes also promotes nitrene transfer to catalytically generate asymmetric dialkylcarbodiimides from azides and isocyanides in a process involving the Nb(V)/Nb(III) redox couple. PMID:26698833

  14. Thermo-Catalytic Methane Decomposition for Hydrogen Production: Effect of Palladium Promoter on Ni-based Catalysts

    OpenAIRE

    Irene Lock Sow Mei; S.S.M. Lock; Dai-Viet N. Vo; Bawadi Abdullah

    2016-01-01

    Hydrogen production from the direct thermo-catalytic decomposition of methane is a promising alternative for clean fuel production. However, thermal decomposition of methane can hardly be of any practical and empirical interest in the industry unless highly efficient and effective catalysts, in terms of both catalytic activity and operational lifetime have been developed. In this study, the effect of palladium (Pd) as a promoter onto Ni supported on alumina catalyst has been investigated by u...

  15. Core–shell nanospheres Pt@SiO2 for catalytic hydrogen production

    International Nuclear Information System (INIS)

    Highlights: • Pt@SiO2 core–shell NPs are synthesized via a simple one-pot synthetic route. • Ultrafine Pt NPs (∼4 nm) are embedded in well-proportioned SiO2 nanospheres. • Pt@SiO2 shows a high activity and good durability for H2 generation from AB. - Abstract: Ultrafine platinum nanoparticles (NPs) embedded in silica nanospheres (Pt@SiO2) have been synthesized in a NP-5/cyclohexane reversed-micelle system followed by NaBH4 reduction. The as-synthesized core–shell nanocatalysts Pt@SiO2 were characterized by scanning electron microscopy, transmission electron microscopes, X-ray powder diffraction analysis, energy dispersive X-ray spectrometer and nitrogen adsorption–desorption investigations. Interestingly, the as-synthesized core–shell nanocatalysts Pt@SiO2 showed an excellent catalytic performance in hydrogen generation from the hydrolysis of ammonia borane (BH3NH3, AB) at room temperature. Especially, the catalytic performance of the Pt@SiO2 remained almost unchanged after the five recycles and even after the heat treatment (673 K), because the silica shells inhibit aggregation or deformation of the metal cores. Besides, the kinetic studies showed that the catalytic hydrolysis of AB was first order with respect to the catalyst concentration and zero order with respect to the substrate concentration, respectively. The excellent catalytic activity and stability of Pt@SiO2 can make it have a bright future in the practical application

  16. Synthesis of antidepressant duloxetine via asymmetric transfer hydrogenation

    Institute of Scientific and Technical Information of China (English)

    Shan Zhen He; Xue Ming Li; Jia Dai; Ming Yan

    2008-01-01

    Antidepressant duloxetine (1) was prepared via asymmetric transfer hydrogenation of 3-(dimethylamino)-1-(thiophen-2-yl)propan-1-one (3). The Ru(Ⅱ), Rh(Ⅲ) and Ir(Ⅲ) complexes of several chiral ligands were examined as the catalyst and(S,S)-N-tosyl-1,2-diphenyl ethylenediamine (TsDPEN)-Ru(Ⅱ) complex was found to provide good yield and excellent enantios-electivity.

  17. Numerical study of methanol–steam reforming and methanol–air catalytic combustion in annulus reactors for hydrogen production

    International Nuclear Information System (INIS)

    Highlights: ► Performance of mini-scale integrated annulus reactors for hydrogen production. ► Flow rates fed to combustor and reformer control the reactor performance. ► Optimum performance is found from balance of flow rates to combustor and reformer. ► Better performance can be found when shell side is designed as combustor. -- Abstract: This study presents the numerical simulation on the performance of mini-scale reactors for hydrogen production coupled with liquid methanol/water vaporizer, methanol/steam reformer, and methanol/air catalytic combustor. These reactors are designed similar to tube-and-shell heat exchangers. The combustor for heat supply is arranged as the tube or shell side. Based on the obtained results, the methanol/air flow rate through the combustor (in terms of gas hourly space velocity of combustor, GHSV-C) and the methanol/water feed rate to the reformer (in terms of gas hourly space velocity of reformer, GHSV-R) control the reactor performance. With higher GHSV-C and lower GHSV-R, higher methanol conversion can be achieved because of higher reaction temperature. However, hydrogen yield is reduced and the carbon monoxide concentration is increased due to the reversed water gas shift reaction. Optimum reactor performance is found using the balance between GHSV-C and GHSV-R. Because of more effective heat transfer characteristics in the vaporizer, it is found that the reactor with combustor arranged as the shell side has better performance compared with the reactor design having the combustor as the tube side under the same operating conditions.

  18. 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...

  19. Evaluation of hydroconverted residues. Rationalization of analytical data through hydrogen transfer balance

    Energy Technology Data Exchange (ETDEWEB)

    Bacaud, Robert; Rouleau, Loiec [Institut de Recherches sur la Catalyse, CNRS, 2 Avenue Albert Einstein, 69626 Villeurbanne (France); Cebolla, Vicente L.; Membrado, Luis; Vela, Jesus [Departamento de Procesos Quimicos, Instituto de Carboquimica, CSIC, Calle Poeta Luciano Gracia 5, 50015 Zaragoza (Spain)

    1998-08-27

    Analytical evaluation of petroleum based materials and processed feeds is a complex task relying on a compromise between tedious in-depth characterizations and fast responding tools for process control. In the present paper, a large number of hydroprocessed vacuum residues, obtained either under catalytic or thermal conditions, have been submitted to the following analytical techniques: Simulated distillation, coupled Simdist/MS, UV spectroscopy, {sup 13}C NMR, quantitative thin-layer chromatography/FID, vapor phase osmometry. A confrontation of analytical data in the light of correlations with hydrogen transfer evaluation is proposed, which accounts for observed variations in aromatic content. Conradson carbon residue largely influences the results obtained with some of the examined techniques. Apparent discrepancies are rationalized and a strategy for a comprehensive analytical evaluation of hydroprocessed feeds is proposed

  20. Co-production of hydrogen and carbon nanotubes on nickel foam via methane catalytic decomposition

    Science.gov (United States)

    Ping, Dan; Wang, Chaoxian; Dong, Xinfa; Dong, Yingchao

    2016-04-01

    The co-production of COx-free hydrogen and carbon nanotubes (CNTs) was achieved on 3-dimensional (3D) macroporous nickel foam (NF) via methane catalytic decomposition (MCD) over nano-Ni catalysts using chemical vapor deposition (CVD) technique. By a simple coating of a NiO-Al2O3 binary mixture sol followed by a drying-calcination-reduction treatment, NF supported composite catalysts (denoted as NiyAlOx/NF) with Al2O3 transition-layer incorporated with well-dispersed nano-Ni catalysts were successfully prepared. The effects of Ni loading, calcination temperature and reaction temperature on the performance for simultaneous production of COx-free hydrogen and CNTs were investigated in detail. Catalysts before and after MCD were characterized by XRD, TPR, SEM, TEM, TG and Raman spectroscopy technology. Results show that increasing Ni loading, lowering calcination temperature and optimizing MCD reaction temperature resulted in high production efficiency of COx-free H2 and carbon, but broader diameter distribution of CNTs. Through detailed parameter optimization, the catalyst with a Ni/Al molar ratio of 0.1, calcination temperature of 550 °C and MCD temperature of 650 °C was favorable to simultaneously produce COx-free hydrogen with a growth rate as high as 10.3% and CNTs with uniform size on NF.

  1. Forced flow heat transfer of supercritical hydrogen for superconductor cooling

    Science.gov (United States)

    Shiotsu, M.; Shirai, Y.; Tatsumoto, H.; Hata, K.; Kobayashi, H.; Naruo, Y.; Inatani, H.

    2014-01-01

    Heat transfer from inner side of a vertical tube to forced flow of hydrogen was measured at the pressure of 1.5 MPa. The test tubes were made of stainless steel 316L with the inner diameters from 3 mm to 9 mm and lengths from 100 mm to 250 mm. Heat transfer curves were obtained by gradually increasing the heating current to the test tube and raising the surface temperature up to around 200 K. Inlet fluid temperature and flow velocity were varied from 21 to 30 K and 0.5 to 12 m/s, respectively. Effects of inlet temperature, flow velocity and tube dimension were clearly observed. The heat transfer curve for each flow velocity consists of a lower temperature region with a higher gradient and higher temperature region with a lower gradient. The experimental results were compared with the authors' correlation presented formerly. It was confirmed that this correlation can describe the experimental results obtained here.

  2. Catalytic on-board hydrogen production from methanol and ammonia for mobile application

    Energy Technology Data Exchange (ETDEWEB)

    Soerijanto, H.

    2008-08-15

    This PhD thesis deals with the catalytic hydrogen production for mobile application, for example for the use in fuel cells for electric cars. Electric powered buses with fuel cells as driving system are well known, but the secure hydrogen storage in adequate amounts for long distance drive is still a topic of discussion. Methanol is an excellent hydrogen carrier. First of all it has a high H:C ratio and therefore a high energy density. Secondly the operating temperature of steam reforming of methanol is comparatively low (250 C) and there is no risk of coking since methanol has no C-C bond. Thirdly methanol is a liquid, which means that the present gasoline infrastructure can be used. For the further development of catalysts and for the construction of a reformer it is very important to characterize the catalysts very well. For the dimensioning and the control of an on-board production of hydrogen it is essential to draw accurately on the thermodynamic, chemical and kinetic data of the reaction. At the first part of this work the mesoporous Cu/ZrO{sub 2}/CeO{sub 2}-catalysts with various copper contents were characterized and their long-term stability and selectivity were investigated, and the kinetic data were determined. Carbon monoxide is generated by reforming of carbon containing material. This process is undesired since CO poisons the Pt electrode of the fuel cell. The separation of hydrogen by metal membranes is technically feasible and a high purity of hydrogen can be obtained. However, due to their high density this procedure is not favourable because of its energy loss. In this study a concept is presented, which enables an autothermal mode by application of ceramic membrane and simultaneously could help to deal with the CO problem. The search for an absolutely selective catalyst is uncertain. The production of CO can be neither chemically nor thermodynamically excluded, if carbon is present in the hydrogen carrier. Since enrichment or separation are

  3. Studies on Hydrogen Selective Silica Membranes and the Catalytic Reforming of CH4 with CO2 in a Membrane Reactor

    OpenAIRE

    Lee, Doohwan

    2003-01-01

    In this work the synthesis, characterization, and gas transport properties of hydrogen selective silica membranes were studied along with the catalytic reforming of CH4 with CO2 (CH4 + CO z 2 CO + 2 H2) in a hydrogen separation membrane reactor. The silica membranes were prepared by chemical vapor deposition (CVD) of a thin SiO2 layer on porous supports (Vycor glass and alumina) using thermal decomposition of tetraethylorthosilicate (TEOS) in an inert atmosphere. These membranes displayed h...

  4. Pt3Co concave nanocubes: synthesis, formation understanding, and enhanced catalytic activity toward hydrogenation of styrene.

    Science.gov (United States)

    Wang, Chenyu; Lin, Cuikun; Zhang, Lihua; Quan, Zewei; Sun, Kai; Zhao, Bo; Wang, Feng; Porter, Nathan; Wang, Yuxuan; Fang, Jiye

    2014-02-01

    We report a facile synthesis route to prepare high-quality Pt3Co nanocubes with a concave structure, and further demonstrate that these concave Pt3Co nanocubes are terminated with high-index crystal facets. The success of this preparation is highly dependent on an appropriate nucleation process with a successively anisotropic overgrowth and a preservation of the resultant high-index planes by control binding of oleyl-amine/oleic acid with a fine-tuned composition. Using a hydrogenation of styrene as a model reaction, these Pt3Co concave nanocubes as a new class of nanocatalysts with more open structure and active atomic sites located on their high-index crystallographic planes exhibit an enhanced catalytic activity in comparison with low-indexed surface terminated Pt3Co nanocubes in similar size. PMID:24382713

  5. Effect of Catalytic Cylinders on Autothermal Reforming of Methane for Hydrogen Production in a Microchamber Reactor

    Directory of Open Access Journals (Sweden)

    Yunfei Yan

    2014-01-01

    Full Text Available A new multicylinder microchamber reactor is designed on autothermal reforming of methane for hydrogen production, and its performance and thermal behavior, that is, based on the reaction mechanism, is numerically investigated by varying the cylinder radius, cylinder spacing, and cylinder layout. The results show that larger cylinder radius can promote reforming reaction; the mass fraction of methane decreased from 26% to 21% with cylinder radius from 0.25 mm to 0.75 mm; compact cylinder spacing corresponds to more catalytic surface and the time to steady state is decreased from 40 s to 20 s; alteration of staggered and aligned cylinder layout at constant inlet flow rates does not result in significant difference in reactor performance and it can be neglected. The results provide an indication and optimize performance of reactor; it achieves higher conversion compared with other reforming reactors.

  6. Preparation and catalytic properties of honeycomb catalyst for hydrogen isotope oxidation

    International Nuclear Information System (INIS)

    Graphical abstract: - Highlights: • Honeycomb catalysts with good physical properties were prepared for detritiation. • The catalysts increase gas flow rate significantly without decreasing the conversion rate. • The catalysts were used at room temperature with high H2 conversion rate. • The confines of H2 concentration and flow rate for catalyst application were tested. - Abstract: The method of catalytic oxidation and adsorption is widely used for atmosphere detritiation. But traditional particle catalyst has large gas resistance, which limited the space velocity for detritiation. Honeycomb catalyst can enormously increase the gas handling capacity due to its low pressure drop and high dispersity of active ingredients, but has not been used in detritiation so far. A coating of alumina was deposited on the honeycomb substrate of cordierite using ultrasonic technology. By the method of excessive impregnating, noble metal (Pt or Pd) supported catalysts were prepared. The catalysts were characterized by X-ray diffraction (XRD), N2-adsorption/desorption (Brunauer–Emmet–Teller – BET method), scanning electron microscope (SEM) and laser particles sizer. The result shows that the alumina coatings are well distributed, well knitted and the specific surface area of honeycomb catalyst rises to about 20 m2/g. Catalytic activities were evaluated by H2 conversion rate in gas mixture (with different H2 concentration and various flow rates). The results indicated that all catalysts exhibited excellent catalytic performance for H2 oxidation; the conversions of hydrogen were 100% at room temperature when the gas space velocity was up to 6 × 105 h−1

  7. Hazelnut shell to hydrogen-rich gaseous products via catalytic gasification process

    Energy Technology Data Exchange (ETDEWEB)

    Demirbas, A. [Selcuk Univ., Dept. of Chemical Engineering, Konya (Turkey)

    2004-01-15

    The gasification of biomass is a thermal treatment, which results in a high production of gaseous products and small quantities of char and ash. Steam reforming of hydrocarbons, partial oxidation of heavy oil residues, selected steam reforming of aromatic compounds, and gasification of coals and solid wastes to yield a mixture of H{sub 2} and CO (syngas), followed by a water-gas shift reaction to produce H{sub 2} and CO{sub 2}, are well-established processes. The samples, both untreated and impregnated with a catalyst, were pyrolyzed and gasified at 770, 925, 975, and 1025 K, and 975, 1075, 1175, and 1225 K temperatures, respectively. K{sub 2}CO{sub 3} was used as a catalyst, 10.0, 20.0, 30.0, and 50.0 wt% of the shell sample, in the catalytic-pyrolysis runs. The ratios of water-to-hazelnut shell were 0.7 and 1.9 in steam gasification runs. The total volume and the yield of gas from both pyrolysis and gasification increase with increasing temperature. The highest hydrogen-rich gas yield was obtained from the catalytic gasification run (water/hazelnut shell = 1.9) at 1225 K. (Author)

  8. Detection of hydrogen peroxide in Photosystem II (PSII using catalytic amperometric biosensor

    Directory of Open Access Journals (Sweden)

    Ankush ePrasad

    2015-10-01

    Full Text Available Hydrogen peroxide (H2O2 is known to be generated in Photosystem II (PSII via enzymatic and non-enzymatic pathways. Hydrogen peroxide (H2O2 is known to be generated in Photosystem II (PSII via enzymatic and non-enzymatic pathways. Detection of H2O2 by different spectroscopic techniques has been explored, however its sensitive detection has always been a challenge in photosynthetic research. During the recent past, fluorescence probes such as Amplex Red has been used but is known to either lack specificity or limitation with respect to the minimum detection limit of H2O2. We have employed an electrochemical biosensor for real time monitoring of H2O2 generation at the level of sub-cellular organelles. The electrochemical biosensor comprises of counter electrode and working electrodes. The counter electrode is a platinum plate, while the working electrode is a mediator based catalytic amperometric biosensor device developed by the coating of a carbon electrode with osmium-horseradish peroxidase which acts as H2O2 detection sensor. In the current study, generation and kinetic behaviour of H2O2 in PSII membranes have been studied under light illumination. Electrochemical detection of H2O2 using the catalytic amperometric biosensor device is claimed to serve as a promising technique for detection of H2O2 in photosynthetic cells and subcellular structures including PSII or thylakoid membranes. It can also provide a precise information on qualitative determination of H2O2 and thus can be widely used in photosynthetic research.

  9. Ab initio molecular dynamics simulations for the role of hydrogen in catalytic reactions of furfural on Pd(111)

    Science.gov (United States)

    Xue, Wenhua; Dang, Hongli; Liu, Yingdi; Jentoft, Friederike; Resasco, Daniel; Wang, Sanwu

    2014-03-01

    In the study of catalytic reactions of biomass, furfural conversion over metal catalysts with the presence of hydrogen has attracted wide attention. We report ab initio molecular dynamics simulations for furfural and hydrogen on the Pd(111) surface at finite temperatures. The simulations demonstrate that the presence of hydrogen is important in promoting furfural conversion. In particular, hydrogen molecules dissociate rapidly on the Pd(111) surface. As a result of such dissociation, atomic hydrogen participates in the reactions with furfural. The simulations also provide detailed information about the possible reactions of hydrogen with furfural. Supported by DOE (DE-SC0004600). This research used the supercomputer resources of the XSEDE, the NERSC Center, and the Tandy Supercomputing Center.

  10. Long-Range Electrostatics-Induced Two-Proton Transfer Captured by Neutron Crystallography in an Enzyme Catalytic Site.

    Science.gov (United States)

    Gerlits, Oksana; Wymore, Troy; Das, Amit; Shen, Chen-Hsiang; Parks, Jerry M; Smith, Jeremy C; Weiss, Kevin L; Keen, David A; Blakeley, Matthew P; Louis, John M; Langan, Paul; Weber, Irene T; Kovalevsky, Andrey

    2016-04-11

    Neutron crystallography was used to directly locate two protons before and after a pH-induced two-proton transfer between catalytic aspartic acid residues and the hydroxy group of the bound clinical drug darunavir, located in the catalytic site of enzyme HIV-1 protease. The two-proton transfer is triggered by electrostatic effects arising from protonation state changes of surface residues far from the active site. The mechanism and pH effect are supported by quantum mechanics/molecular mechanics (QM/MM) calculations. The low-pH proton configuration in the catalytic site is deemed critical for the catalytic action of this enzyme and may apply more generally to other aspartic proteases. Neutrons therefore represent a superb probe to obtain structural details for proton transfer reactions in biological systems at a truly atomic level. PMID:26958828

  11. High performing and stable supported nano-alloys for the catalytic hydrogenation of levulinic acid to gamma-valerolactone

    NARCIS (Netherlands)

    Luo, Wenhao; Meenakshisundaram, Sankar; Beale, Andrew M.; He, Qian; Kiely, Christopher J.; Bruijnincx, Pieter C. A.; Weckhuysen, Bert M.

    2015-01-01

    The catalytic hydrogenation of levulinic acid, a key platform molecule in many biorefinery schemes, into gamma-valerolactone is considered as one of the pivotal reactions to convert lignocellulose-based biomass into renewable fuels and chemicals. Here we report on the development of highly active, s

  12. Experimental and Numerical Evaluation of the By-Pass Flow in a Catalytic Plate Reactor for Hydrogen Production

    DEFF Research Database (Denmark)

    Sigurdsson, Haftor Örn; Kær, Søren Knudsen

    2011-01-01

    Numerical and experimental study is performed to evaluate the reactant by-pass flow in a catalytic plate reactor with a coated wire mesh catalyst for steam reforming of methane for hydrogen generation. By-pass of unconverted methane is evaluated under different wire mesh catalyst width to reactor...

  13. SYNTHESIS OF POLYMER-STABILIZED PLATINUM/RUTHENIUM BIMETALLIC COLLOIDS AND THEIR CATALYTIC PROPERTIES FOR SELECTIVE HYDROGENATION OF CROTONALDEHYDE

    Institute of Scientific and Technical Information of China (English)

    Wei-xia Tu; Han-fan Liu

    2005-01-01

    Polymer-stabilized platinum/ruthenium bimetallic colloids (Pt/Ru) were synthesized by polyol reduction with microwave irradiation and characterized by TEM and XPS. The colloidal nanoparticles have small and narrow size distributions. Catalytic performance of the Pt/Ru colloidal catalysts was investigated on the selective hydrogenation of crontonaldehyde (CRAL). A suitable amount of the added metal ions and base can improve the selectivity of CRAL to crotylalcohol (CROL) remarkably. The catalytic activity and the selectivity are dependent on the compositions of bimetallic colloids. Thereinto, PVP-stabilized 9Pt/1Ru colloid with a molar ratio of metals Pt:Ru = 9:1 shows the highest catalytic selectivity 77.3% to CROL at 333 K under 4.0 MPa of hydrogen.

  14. Promoting effect of Ir on the catalytic property of Ru/ZnO catalysts for selective hydrogenation of crotonaldehyde

    International Nuclear Information System (INIS)

    A series of ZnO supported Ru–Ir bimetal catalysts were prepared and tested for vapor-phase selective hydrogenation of crotonaldehyde. The addition of Ir could effectively promote the catalytic performance, especially the catalyst stability. A Ru–0.5Ir/ZnO catalyst showed the highest activity (a conversion of 63.3%) and selectivity to crotyl alcohol (94.4%) after 30 h reaction. The enhanced stability was attributed to the modified electronic property of Ru by the formation of RuIr alloy as the X-ray photoelectron spectroscopy results showed charge transfer from Ru to Ir, as well as the weakened surface acidity in the Ru–Ir/ZnO catalyst as evidenced by NH3 temperature-programmed desorption technique. Besides, the deactivation of the catalysts was due to the strong chemisorption of CO on the metal surface via decarbonylation reaction and deposition of organic compounds on the catalyst surface, which was characterized by CO poisoning experiment, CO temperature-programmed desorption and temperature-programmed oxidation methods.

  15. Highly dispersed ruthenium hydroxide supported on titanium oxide effective for liquid-phase hydrogen-transfer reactions.

    Science.gov (United States)

    Yamaguchi, Kazuya; Koike, Takeshi; Kim, Jung Won; Ogasawara, Yoshiyuki; Mizuno, Noritaka

    2008-01-01

    Supported ruthenium hydroxide catalysts (Ru(OH)(x)/support) were prepared with three different TiO(2) supports (anatase TiO(2) (TiO(2)(A), BET surface area: 316 m(2) g(-1)), anatase TiO(2) (TiO(2)(B), 73 m(2) g(-1)), and rutile TiO(2) (TiO(2)(C), 3.2 m(2) g(-1))), as well as an Al(2)O(3) support (160 m(2) g(-1)). Characterizations with X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), electron spin resonance (ESR), and X-ray absorption fine structure (XAFS) showed the presence of monomeric ruthenium(III) hydroxide and polymeric ruthenium(III) hydroxide species. Judging from the coordination numbers of the nearest-neighbor Ru atoms and the intensities of the ESR signals, the amount of monomeric hydroxide species increased in the order of Ru(OH)(x)ruthenium hydroxide catalysts, especially Ru(OH)(x)/TiO(2)(A), showed high catalytic activities and selectivities for liquid-phase hydrogen-transfer reactions, such as racemization of chiral secondary alcohols and the reduction of carbonyl compounds and allylic alcohols. The catalytic activities of Ru(OH)(x)/TiO(2)(A) for these hydrogen-transfer reactions were at least one order of magnitude higher than those of previously reported heterogeneous catalysts, such as Ru(OH)(x)/Al(2)O(3). These catalyses were truly heterogeneous, and the catalysts recovered after the reactions could be reused several times without loss of catalytic performance. The reaction rates monotonically increased with an increase in the amount of monomeric ruthenium hydroxide species, which suggests that the monomeric species are effective for these hydrogen-transfer reactions. PMID:19021181

  16. Heat and mass transfer of hydrogen storage in metal-hydrogen reactors

    International Nuclear Information System (INIS)

    Hydrogen energy is the best alternative to fossil fuels due to its high calorific value and being environmentally friendly. Hydrogen also produces more energy per unit weight than any other fuel. However, storage problem of hydrogen prevents its wide usage and commercialization. Hydrogen absorption in two LaNi5-H2 reactors is experimentally and theoretically investigated. In the experimental program, two tanks are filled with LaNi5 alloy and hydrogen is charged with a constant pressure. The temperature changes in the tanks are measured at several locations and recorded in a computer. Hydriding process is identified from measured temperature histories. An experimental set up is designed to study main characteristics of hydriding process and effect of bed geometry and heat transfer on the hydriding process. Hydriding process is characterized by exothermic reaction between LaNi5 and H2 and rapid temperature increase due the heat release. Hydriding time mainly depend on the successful heat removal from the bed. A bed geometry which provides more heat transfer area significantly reduces hydriding time. In the theoretical program, a two dimensional mathematical model, which considers complex heat and mass transfer and fluid flow is developed and numerically solved. The governing equations are numerically solved and calculated results are compared with experimental data. It is found that mathematical model adequately captures the main physics of the hydriding process and can be employed for a better hydride bed design to reduce hydriding time. A reasonable agreement between the numerical results and experimental data is obtained. (authors)

  17. The quantum dynamics of proton transfer in the hydrogen bond

    International Nuclear Information System (INIS)

    The wavefunctions of particles extend beyond the classically accessible regions of potential energy surfaces. A manifestation of this partial delocalisation is the quantum mechanical tunnelling effect which enables a particle to escape from a metastable potential well. Tunnelling is most important for the lightest atoms, so that the determination of its contribution to proton transfer, one of the most fundamental chemical reactions, is an important issue. NMR techniques have been employed to study the motion of hydrogen atoms in the hydrogen bond of benzoic acid, a system which has emerged as particularly suitable since proton transfer occurs in a near symmetric double minimum potential (DMP). The influence of proton tunnelling has been investigated by making direct measurements of the spectral density function from the dispersion of the spin-lattice relaxation time using field-cycling. The incoherent tunnelling rate is measured directly from the half-width of the spectral density function at low temperature and the proton transfer rate has been determined over the full range of temperature. This reveals the smooth transition between quantum and classical behaviour. The dynamics have been modelled as the behaviour of a particle in a DMP which is coupled to a bath of quantum oscillators (phonons). At high temperature an Arrhenius rate law applies whereas at low temperatures the dynamics are described by incoherent quantum tunnelling. Models that include only ground state tunnelling fail to fit the observed behaviour in the interfacial region. When tunnelling via excited states of the DMP is included then near perfect agreement with experiment is obtained. This represents the first quantitative study of the role of the excited states in the dynamics of the hydrogen bond. Additional measurements will be presented which investigate the isotope effects of the heavier atoms in the skeletal framework and the effects of hydrostatic pressure. The benefits of using single

  18. Application of microscopy technology in thermo-catalytic methane decomposition to hydrogen

    Energy Technology Data Exchange (ETDEWEB)

    Mei, Irene Lock Sow, E-mail: irene.sowmei@gmail.com; Lock, S. S. M., E-mail: serenelock168@gmail.com; Abdullah, Bawadi, E-mail: bawadi-abdullah@petronas.com.my [Chemical Engineering Department, Universiti Teknologi PETRONAS, Bandar Sri Iskandar, 31750, Perak (Malaysia)

    2015-07-22

    Hydrogen production from the direct thermo-catalytic decomposition of methane is a promising alternative for clean fuel production because it produces pure hydrogen without any CO{sub x} emissions. However, thermal decomposition of methane can hardly be of any practical and empirical interest in the industry unless highly efficient and effective catalysts, in terms of both specific activity and operational lifetime have been developed. In this work, bimetallic Ni-Pd on gamma alumina support have been developed for methane cracking process by using co-precipitation and incipient wetness impregnation method. The calcined catalysts were characterized to determine their morphologies and physico-chemical properties by using Brunauer-Emmett-Teller method, Field Emission Scanning Electron Microscopy, Energy-dispersive X-ray spectroscopy and Thermogravimetric Analysis. The results suggested that that the catalyst which is prepared by the co-precipitation method exhibits homogeneous morphology, higher surface area, have uniform nickel and palladium dispersion and higher thermal stability as compared to the catalyst which is prepared by wet impregnation method. This characteristics are significant to avoid deactivation of the catalysts due to sintering and carbon deposition during methane cracking process.

  19. Application of microscopy technology in thermo-catalytic methane decomposition to hydrogen

    International Nuclear Information System (INIS)

    Hydrogen production from the direct thermo-catalytic decomposition of methane is a promising alternative for clean fuel production because it produces pure hydrogen without any COx emissions. However, thermal decomposition of methane can hardly be of any practical and empirical interest in the industry unless highly efficient and effective catalysts, in terms of both specific activity and operational lifetime have been developed. In this work, bimetallic Ni-Pd on gamma alumina support have been developed for methane cracking process by using co-precipitation and incipient wetness impregnation method. The calcined catalysts were characterized to determine their morphologies and physico-chemical properties by using Brunauer-Emmett-Teller method, Field Emission Scanning Electron Microscopy, Energy-dispersive X-ray spectroscopy and Thermogravimetric Analysis. The results suggested that that the catalyst which is prepared by the co-precipitation method exhibits homogeneous morphology, higher surface area, have uniform nickel and palladium dispersion and higher thermal stability as compared to the catalyst which is prepared by wet impregnation method. This characteristics are significant to avoid deactivation of the catalysts due to sintering and carbon deposition during methane cracking process

  20. Application of microscopy technology in thermo-catalytic methane decomposition to hydrogen

    Science.gov (United States)

    Mei, Irene Lock Sow; Lock, S. S. M.; Abdullah, Bawadi

    2015-07-01

    Hydrogen production from the direct thermo-catalytic decomposition of methane is a promising alternative for clean fuel production because it produces pure hydrogen without any COx emissions. However, thermal decomposition of methane can hardly be of any practical and empirical interest in the industry unless highly efficient and effective catalysts, in terms of both specific activity and operational lifetime have been developed. In this work, bimetallic Ni-Pd on gamma alumina support have been developed for methane cracking process by using co-precipitation and incipient wetness impregnation method. The calcined catalysts were characterized to determine their morphologies and physico-chemical properties by using Brunauer-Emmett-Teller method, Field Emission Scanning Electron Microscopy, Energy-dispersive X-ray spectroscopy and Thermogravimetric Analysis. The results suggested that that the catalyst which is prepared by the co-precipitation method exhibits homogeneous morphology, higher surface area, have uniform nickel and palladium dispersion and higher thermal stability as compared to the catalyst which is prepared by wet impregnation method. This characteristics are significant to avoid deactivation of the catalysts due to sintering and carbon deposition during methane cracking process.

  1. An FTIR study on the catalytic effect of water molecules on the reaction of CO successive hydrogenation at 3 K

    International Nuclear Information System (INIS)

    Graphical abstract: This work highlights a selective catalytic action of water molecules on the reaction of CO hydrogenation at 3 K. Research highlights: → [CO/H2O] and [H/H2] are coinjected at 3 K. → H2 molecules condense rapidly at 3 K and screen the reaction mostly at the 1st step. → The observed catalytic effects on CO hydrogenation increase with water concentration. - Abstract: The reaction of successive CO hydrogenation has been performed at 3 K by coinjecting CO molecules and H atoms. The concentration of CO has been progressively reduced and replaced by water molecules to create two different environments where CO and H2O are successively the dominant species in the binary (CO/H2O) mixture. The catalytic effect of water molecules on CO hydrogenation appears clearly since the early times of the experiment and evolves with the formation of the CO/H2/H2O mixed-matrix. The process of CO hydrogenation, initially frozen at the first step of the reaction, is brought to completion through water influence. Water molecules guide the reaction toward the formation of CH3OH and promote different reaction steps depending on water concentration. Water molecules increase the probability of reactive to encounter H atoms either physically, by introducing structural changes in the matrix, or chemically, by raising the number of chemical pathways.

  2. Catalytic selectivity and H-transfer in the hydroconversion of a petroleum residue using dispersed catalysts

    Energy Technology Data Exchange (ETDEWEB)

    Cebolla, V.L.; Membrado, L.; Vela, J.; Bacaud, R.; Rouleau, L. [Instituto de Carboquimica, Zaragoza (Spain). Dept. de Procesos Quimicos

    1995-09-01

    Hydroconversion of a deasphalted vacuum residue of a crude oil has been performed in the presence of various disposable, dispersed catalysts at low concentration (450 ppm of metal) under identical conditions: a plasma-prepared nickel-carbon catalyst, an oil-soluble molybdenum naphthenate, and a commercial nickel-molybdenum supported on alumina, in order to obtain some insight into their influence upon their mechanisms of hydrogen transfer, and to evaluate their selectivities toward the production of various hydrocarbon groups. For this last purpose, a quantitative, rapid and accurate method for hydrocarbon group type analysis has been used, based on an improved system of thin-layer chromatography with flame ionization detection. The catalysts significantly affect the quantitative distribution of hydrocarbon groups without producing new chemical families. The total hydrogen consumption is only slightly increased in the presence of these kind of catalysts. However, a different distribution of the hydrogen is achieved depending on the catalyst. Molybdenum naphthenate exhibits the higher hydrogen incorporation to its derived distillates, which in turn present significantly higher number-average molecular weight and percentage of saturates than those obtained with the other catalysts. For every catalyst studied, the more the incorporation of hydrogen in distillates, the less the production of coke and gas. Throughout this paper, the agreement between the data obtained from TLC-FID and hydrogen balance is evidenced and explained. 18 refs., 5 figs., 2 tabs.

  3. Hydrogen fuel society and hybrid energy transfer line of hydrogen and electricity

    International Nuclear Information System (INIS)

    Applicability of 1 GW class hybrid energy transfer line (HETL) of hydrogen and electricity is investigated in this report. The rated current is 10 kA, and operation voltage is 100 kV (+50 kV and -50 kV for ground). Delivery capacity of the liquid hydrogen is 100 tons per day. Re-cooling station of the liquid hydrogen is placed on every 10 km of the unit section. High Jc performance under high temperature region around 20 K requires for the SC wire. The special multi-filamentary magnesium diboride (MgB2) wire was developed to suppress the Ic degradation against bending strain. Structure of a coaxial stranded cable is proposed for the design of 10 kA MgB2 cable. Pressure of liquid hydrogen from 0.4 to 0.6 MPa was chosen, in order to keep the liquid phase up to 25 K. It was confirmed that this HETL is one of the attractive energy transportation system which combines hydrogen fuel and SC power transmission. (author)

  4. Catalytic dehydrogenation of isobutane in the presence of hydrogen over Cs-modified Ni{sub 2}P supported on active carbon

    Energy Technology Data Exchange (ETDEWEB)

    Xu, Yanli [Collaborative Innovation Center of Chemical Science and Engineering (Tianjin), Tianjin Key Laboratory of Applied Catalysis Science and Technology, College of Chemical Engineering and Technology, Tianjin University, Tianjin 300072 (China); Sang, Huanxin [Tianjin Academy of Environmental Sciences, Tianjin 300191 (China); Wang, Kang [Collaborative Innovation Center of Chemical Science and Engineering (Tianjin), Tianjin Key Laboratory of Applied Catalysis Science and Technology, College of Chemical Engineering and Technology, Tianjin University, Tianjin 300072 (China); Wang, Xitao, E-mail: wangxt@tju.edu.cn [Collaborative Innovation Center of Chemical Science and Engineering (Tianjin), Tianjin Key Laboratory of Applied Catalysis Science and Technology, College of Chemical Engineering and Technology, Tianjin University, Tianjin 300072 (China)

    2014-10-15

    Graphical abstract: - Highlights: • Ni{sub 2}P catalyst is tested in dehydrogenation of isobutane for the first time. • The effects of Cs promoter on catalytic performance of Ni2P/AC were investigated. • Cs-Ni2P/AC exhibits high activity and selectivity for isobutane dehydrogenation. - Abstract: In this article, an environmentally friendly non-noble-metal class of Cs-Ni{sub 2}P/active carbon (AC) catalyst was prepared and demonstrated to exhibit enhanced catalytic performance in isobutane dehydrogenation. The results of activity tests reveal that Ni/AC catalyst was highly active for isobutane cracking, which led to the formation of abundant methane and coke. After the introduction of phosphorus through impregnation with ammonium di-hydrogen phosphate and H{sub 2}-temperature programmed reduction, undesired cracking reactions were effectively inhibited, and the selectivity to isobutene and stability of catalyst increased remarkably. The characterization results indicate that, after the addition of phosphorous, the improvement of dehydrogenation selectivity is ascribed to the partial positive charges carried on Ni surface in Ni{sub 2}P particles, which decreases the strength of Ni-C bond between Ni and carbonium-ion intermediates and the possibility of excessive dehydrogenation. In addition, Cs-modified Ni{sub 2}P/AC catalysts display much higher catalytic performance as compared to Ni{sub 2}P/AC catalyst. Cs-Ni{sub 2}P-6.5 catalyst has the highest catalytic performance, and the selectivity to isobutene higher than 93% can be obtained even after 4 h reaction. The enhancement in catalytic performance of the Cs-modified catalysts is mainly attributed to the function of Cs to improve the dispersion of Ni{sub 2}P particles, transfer electron from Cs to Ni, and decrease acid site number and strength.

  5. Asymmetric Transfer Hydrogenation of Prochiral Ketones in Aqueous Media with New Water-Soluble Chiral Vicinal Diamine as Ligand

    Institute of Scientific and Technical Information of China (English)

    ZHU Jin; MA Ya-Ping; LIU Hui; CHEN Li; CUI Xin; DENG Jin-Gen

    2003-01-01

    @@ As a consequence of the increasing demand for atom economy and environmental friendly methods, the water soluble ligands and their metal complexes are of great interest in catalytic synthesis because of simpler product sepa ration and the possibility of recycling. [1] Unique reactivity and selectivity are often observed in aqueous reactions. [2]Recently, we have developed a new water-soluble chiral vicinal diamine and synthesized its mono-N-tosylated derivative for the first time. The application of its mono-N-tosylated derivative in catalytic asymmetric transfer hydrogenation of prochiral ketones was examined in aqueous media. High activity (up to > 99 % conv. ) and good enatioselectivity ( up to 98% ee ) were achieved for most of prochiral aromatic ketones in organic solvent free system. [3

  6. Copolymerization of Styrene and Methacrylates in the presence of Catalytic Chain Transfer Agents (Cacti's)

    International Nuclear Information System (INIS)

    The present paper focuses on the use of a Co (II) complex, [Co(afdo-H)] as a catalytic chain transfer agent (CCTA) for controlling molecular weight in copolymerization of styrene (STY) with butyl methacrylate (BMA) and methylmethacrylate (MMA). The catalyst is structurally similar to [co(dmg-H) (BF)] patented by Du Pont as a CCTA. Average catalytic chain transfer constant, C8 of [co(afdo-H) (BF)] for coplymerization of STY with BMA and MMA determined from Maya plot, was found to be in the range of 10-10.This value is lower than the value reported for the [Co(dmg-H)(BF)). In the case of STY-BMA or STY-MMA copolymerization, a considerable reduction in the viscosity average molecular weights (Mv) was observed in the copolymers. The average molecular weight of poly (MMA-BMA) was reduced by a factor of ten compared to the reduction in poly (STY-MMA) and poly (STY-BMA) for the same concentration of the CCTA. (author)

  7. A La-doped Mg-Al mixed metal oxide supported copper catalyst with enhanced catalytic performance in transfer dehydrogenation of 1-decanol.

    Science.gov (United States)

    Zhang, Ming; Zhao, Yajie; Liu, Qian; Yang, Lan; Fan, Guoli; Li, Feng

    2016-01-21

    In the present work, a La-doped Mg-Al mixed metal oxide supported copper catalyst (Cu/La-MgAlO) was synthesized through a layered double hydroxide precursor route. The materials were characterized by powder X-ray diffraction, transmission electron microscopy, CO2-temperature programmed desorption, Fourier transform infrared spectra of CO2 absorption, and X-ray photoelectron spectroscopy. The results revealed that the introduction of a trace amount of La could significantly improve the surface basicity of the Cu/La-MgAlO catalyst, especially strong Lewis basicity. Compared with the undoped supported Cu catalyst, Cu/La-MgAlO exhibited much higher activity and selectivity in the liquid-phase transfer dehydrogenation of 1-decanol with a 1-decanal yield up to 89%. The excellent catalytic efficiency was mainly ascribed to the surface cooperation between the Lewis basic sites and the adjacent Cu(0)/Cu(+) species. That is, basic sites, especially strong-strength basic sites, held the key to the abstraction of protons from the hydroxyl group in 1-decanol, while the adjacent Cu(0) and Cu(+) species were responsible for the hydrogen transfer and the adsorption of styrene in the transfer dehydrogenation and hydrogenation reactions, respectively. This study provides a new method for designing cost-effective supported copper-based catalysts highly efficient for the transfer dehydrogenation of primary aliphatic alcohols by modifying the surface basicity of metal oxide supports. PMID:26659760

  8. Selective Catalytic Synthesis Using the Combination of Carbon Dioxide and Hydrogen: Catalytic Chess at the Interface of Energy and Chemistry.

    Science.gov (United States)

    Klankermayer, Jürgen; Wesselbaum, Sebastian; Beydoun, Kassem; Leitner, Walter

    2016-06-20

    The present Review highlights the challenges and opportunities when using the combination CO2 /H2 as a C1 synthon in catalytic reactions and processes. The transformations are classified according to the reduction level and the bond-forming processes, covering the value chain from high volume basic chemicals to complex molecules, including biologically active substances. Whereas some of these concepts can facilitate the transition of the energy system by harvesting renewable energy into chemical products, others provide options to reduce the environmental impact of chemical production already in today's petrochemical-based industry. Interdisciplinary fundamental research from chemists and chemical engineers can make important contributions to sustainable development at the interface of the energetic and chemical value chain. The present Review invites the reader to enjoy this exciting area of "catalytic chess" and maybe even to start playing some games in her or his laboratory. PMID:27237963

  9. CNN pincer ruthenium catalysts for hydrogenation and transfer hydrogenation of ketones: experimental and computational studies.

    Science.gov (United States)

    Baratta, Walter; Baldino, Salvatore; Calhorda, Maria José; Costa, Paulo J; Esposito, Gennaro; Herdtweck, Eberhardt; Magnolia, Santo; Mealli, Carlo; Messaoudi, Abdelatif; Mason, Sax A; Veiros, Luis F

    2014-10-13

    Reaction of [RuCl(CNN)(dppb)] (1-Cl) (HCNN=2-aminomethyl-6-(4-methylphenyl)pyridine; dppb=Ph2 P(CH2 )4 PPh2 ) with NaOCH2 CF3 leads to the amine-alkoxide [Ru(CNN)(OCH2 CF3 )(dppb)] (1-OCH2 CF3 ), whose neutron diffraction study reveals a short RuO⋅⋅⋅HN bond length. Treatment of 1-Cl with NaOEt and EtOH affords the alkoxide [Ru(CNN)(OEt)(dppb)]⋅(EtOH)n (1-OEt⋅n EtOH), which equilibrates with the hydride [RuH(CNN)(dppb)] (1-H) and acetaldehyde. Compound 1-OEt⋅n EtOH reacts reversibly with H2 leading to 1-H and EtOH through dihydrogen splitting. NMR spectroscopic studies on 1-OEt⋅n EtOH and 1-H reveal hydrogen bond interactions and exchange processes. The chloride 1-Cl catalyzes the hydrogenation (5 atm of H2 ) of ketones to alcohols (turnover frequency (TOF) up to 6.5×10(4) h(-1) , 40 °C). DFT calculations were performed on the reaction of [RuH(CNN')(dmpb)] (2-H) (HCNN'=2-aminomethyl-6-(phenyl)pyridine; dmpb=Me2 P(CH2 )4 PMe2 ) with acetone and with one molecule of 2-propanol, in alcohol, with the alkoxide complex being the most stable species. In the first step, the Ru-hydride transfers one hydrogen atom to the carbon of the ketone, whereas the second hydrogen transfer from NH2 is mediated by the alcohol and leads to the key "amide" intermediate. Regeneration of the hydride complex may occur by reaction with 2-propanol or with H2 ; both pathways have low barriers and are alcohol assisted. PMID:25195979

  10. Catalytic stepwise nitrate hydrogenation in batch-recycle fixed-bed reactors

    International Nuclear Information System (INIS)

    Pd (1.0 wt.%)-Cu (0.3 wt.%) bimetallic and Pd (1.0 wt.%) monometallic catalysts were synthesized by means of incipient-wetness impregnation technique and deposited on alumina spheres (dp = 1.7 mm). The prepared catalysts were tested at T = 298 K and p(H2) = 1.0 bar in the integrated process of catalytic liquid-phase hydrogenation of aqueous nitrate solutions, in which the denitration step was carried out consecutively in separate, single-flow fixed-bed reactor units operating in a batch-recycle mode. In the first reactor packed with a Pd-Cu bimetallic catalyst, nitrate ions were transformed to nitrites at pH 12.5 with a selectivity as high as 93%; the rest was found in the form of ammonium ions. Liquid-phase nitrite hydrogenation to nitrogen in the second reactor unit packed with a Pd monometallic catalyst was conducted at low pH values of 3.7 and 4.5, respectively. Although these values are well below the pHpzc of examined catalyst (6.1), which assured that the nitrite reduction was carried out over a positively charged catalyst surface, up to 15% (23% in the presence of 5.0 g/l NaCl in the solution) of initial nitrite content was converted to undesired ammonium ions. Since a negligible amount of these species (below 0.5 mg/l) was produced at identical operating conditions over a powdered Pd/γ-Al2O3 catalyst, it is believed that the enhanced production of ammonium ions observed in the second fixed-bed reactor is due to the build-up of pH gradients in liquid-filled pores of spherical catalyst particles. Both Pd-Cu bimetallic and Pd monometallic catalysts were chemically resistant in the investigated range of pH values

  11. SYNTHESIS AND CHARACTERIZATION OF A SILICA-SUPPORTED CARBOXYMETHYLCELLULOSE PLATINUM COMPLEX AND ITS CATALYTIC BEHAVIORS FOR HYDROGENATION OF AROMATICS

    Institute of Scientific and Technical Information of China (English)

    TANG Liming; HUANG Meiyu; JIANG Yingyan

    1996-01-01

    A silica-supported carboxymethylcellulose platinum complex (abbreviated as SiO2-CMC-Pt) has been prepared and characterized by XPS. Its catalytic properties for hydrogenation of aromatic compounds were studied. The results showed that this catalyst could catalyze the hydrogenation of phenol, anisol, p-cresol, benzene and toluene to cyclohexanol, cyclohexyl methyl ether, p-methyl cyclohexanol, cyclohexane and methylcyclohexane, respectively in 100% yield at 30℃ and 1 atm. In the hydrogenation of phenol,COO/Pt ratio in SiO2-CMC-Pt has much influence on the initial hydrogenation rate and the selectivity for the intermediate product, cyclohexanone. The highest initial rate and the highest yield of cyclohexanone both occur at COO/Pt ratio of 6. The complex is stable during the reaction and can be used repeatedly.

  12. Immobilization of the [FeFe]-hydrogenase CrHydA1 on a gold electrode: design of a catalytic surface for the production of molecular hydrogen.

    Science.gov (United States)

    Krassen, Henning; Stripp, Sven; von Abendroth, Gregory; Ataka, Kenichi; Happe, Thomas; Heberle, Joachim

    2009-06-01

    Hydrogenase-modified electrodes are a promising catalytic surface for the electrolysis of water with an overpotential close to zero. The [FeFe]-hydrogenase CrHydA1 from the photosynthetic green alga Chlamydomonas reinhardtii is the smallest [FeFe]-hydrogenase known and exhibits an extraordinary high hydrogen evolution activity. For the first time, we immobilized CrHydA1 on a gold surface which was modified by different carboxy-terminated self-assembled monolayers. The immobilization was in situ monitored by surface-enhanced infrared spectroscopy. In the presence of the electron mediator methyl viologen the electron transfer from the electrode to the hydrogenase was detected by cyclic voltammetry. The hydrogen evolution potential (-290 mV vs NHE, pH 6.8) of this protein modified electrode is close to the value for bare platinum (-270 mV vs NHE). The surface coverage by CrHydA1 was determined to 2.25 ng mm(-2) by surface plasmon resonance, which is consistent with the formation of a protein monolayer. Hydrogen evolution was quantified by gas chromatography and the specific hydrogen evolution activity of surface-bound CrHydA1 was calculated to 1.3 micromol H(2)min(-1)mg(-1) (or 85 mol H(2)min(-1)mol(-1)). In conclusion, a viable hydrogen-evolving surface was developed that may be employed in combination with immobilized photosystems to provide a platform for hydrogen production from water and solar energy with enzymes as catalysts. PMID:19480942

  13. Data acquisition and quantitative analysis of stable hydrogen isotope in liquid and gas in the liquid phase catalytic exchange process

    International Nuclear Information System (INIS)

    A pilot plant for the Liquid Phase Catalytic Exchange process was built and has been operating to test the hydrophobic catalyst developed to remove the tritium generated at the CANDU nuclear power plants. The methods of quantitative analysis of hydrogen stable isotope were compared. Infrared spectroscopy was used for the liquid samples, and gas chromatography with hydrogen carrier gas showed the best result for gas samples. Also, a data acquisition system was developed to record the operation parameters. This record was very useful to investigate the causes of the system trip

  14. Applications of the water--gas shift reaction. II. Catalytic exchange of deuterium for hydrogen at saturated carbon

    International Nuclear Information System (INIS)

    Previous studies on the homogeneous catalysis of the water-gas shift reaction by metal complexes of groups 6 and 8 had been carried out using aqueous alcoholic solutions of group 8 metal carbonyl complexes made basic with KOH. Substitution of triethylamine (Et3N) for KOH as base and alcohol for solvent led to the discovery that Et3N in the presence of D2O, CO, and Rh6(CO)16 at 1500C undergoes an unusual catalytic exchange of deuterium for hydrogen. A suggested mechanism for this reaction is given and includes activation of hydrogen at a saturated carbon

  15. Hydrogen production from catalytic reforming of the aqueous fraction of pyrolysis bio-oil with modified Ni-Al catalysts

    OpenAIRE

    D. Yao; Wu, C.; Yang, H; Hu, Q.; Nahil, MA; H Chen; Williams, PT

    2014-01-01

    Hydrogen production from renewable resources has received extensive attention recently for a sustainable and renewable future. In this study, hydrogen was produced from catalytic steam reforming of the aqueous fraction of crude bio-oil, which was obtained from pyrolysis of biomass. Five Ni-Al catalysts modified with Ca, Ce, Mg, Mn and Zn were investigated using a fixed-bed reactor. Optimized process conditions were obtained with a steam reforming temperature of 800 °C and a steam to carbon ra...

  16. Supported catalysts based on layered double hydroxides for catalytic oxidation and hydrogenation: general functionality and promising application prospects.

    Science.gov (United States)

    Feng, Junting; He, Yufei; Liu, Yanan; Du, Yiyun; Li, Dianqing

    2015-08-01

    Oxidation and hydrogenation catalysis plays a crucial role in the current chemical industry for the production of key chemicals and intermediates. Because of their easy separation and recyclability, supported catalysts are widely used in these two processes. Layered double hydroxides (LDHs) with the advantages of unique structure, composition diversity, high stability, ease of preparation and low cost have shown great potential in the design and synthesis of novel supported catalysts. This review summarizes the recent progress in supported catalysts by using LDHs as supports/precursors for catalytic oxidation and hydrogenation. Particularly, partial hydrogenation of acetylene, hydrogenation of dimethyl terephthalate, methanation, epoxidation of olefins, elimination of NOx and SOx emissions, and selective oxidation of biomass have been chosen as representative reactions in the petrochemical, fine chemicals, environmental protection and clean energy fields to highlight the potential application and the general functionality of LDH-based catalysts in catalytic oxidation and hydrogenation. Finally, we concisely discuss some of the scientific challenges and opportunities of supported catalysts based on LDH materials. PMID:25962432

  17. Catalytic effect of additional metallic phases on the hydrogen absorption behavior of a Zr-Based alloy

    International Nuclear Information System (INIS)

    The electrochemical hydrogen absorption of electrodes containing Zr0.9Ti0.1(Ni0.5Mn0.25Cr0.20V0.05)2 is studied in alkaline media by monitoring the activation and discharge capacity along charge-discharge cycling.The considered alloy is tested in both as melted and annealed condition in order to investigate the catalytic effect of small amounts of micro segregated secondary phases of the Zr-Ni system. Since these catalytic phases are only present in the as melted alloys, tests are also carried out using a composite material elaborated from powders of the annealed alloy with the addition of 18 wt.% of the suspected catalytic phases, melted separately.The hydrogen absorption-desorption behavior for the different cases is discussed and correlated with the metallurgical characterization of the materials.The catalytic effects are studied employing cyclic voltammetry and electrochemical impedance techniques. The results are analyzed in terms of a developed physicochemical model

  18. High performing and stable supported nano-alloys for the catalytic hydrogenation of levulinic acid to gamma-valerolactone

    OpenAIRE

    Luo, Wenhao; Meenakshisundaram, Sankar; Beale, Andrew M; He, Qian; Kiely, Christopher J.; Bruijnincx, Pieter C. A.; Weckhuysen, Bert M.

    2015-01-01

    The catalytic hydrogenation of levulinic acid, a key platform molecule in many biorefinery schemes, into gamma-valerolactone is considered as one of the pivotal reactions to convert lignocellulose-based biomass into renewable fuels and chemicals. Here we report on the development of highly active, selective and stable supported metal catalysts for this reaction and on the beneficial effects of metal nano-alloying. Bimetallic random alloys of gold-palladium and ruthenium-palladium supported on...

  19. High performing and stable supported nano-alloys for the catalytic hydrogenation of levulinic acid to γ-valerolactone

    OpenAIRE

    W. Luo; Sankar, M.; Beale, A.M.; Q. He; Kiely, C. J.; Bruijnincx, P. C.; Weckhuysen, B. M.

    2015-01-01

    The catalytic hydrogenation of levulinic acid, a key platform molecule in many biorefinery schemes, into γ-valerolactone is considered as one of the pivotal reactions to convert lignocellulose-based biomass into renewable fuels and chemicals. Here we report on the development of highly active, selective and stable supported metal catalysts for this reaction and on the beneficial effects of metal nano-alloying. Bimetallic random alloys of gold-palladium and ruthenium-palladium supported on tit...

  20. Ruthenium supported on magnetic nanoparticles: An efficient and recoverable catalyst for hydrogenation of alkynes and transfer hydrogenation of carbonyl compounds

    Science.gov (United States)

    Ruthenium supported on surface modified magnetic nanoparticles (NiFe2O4) has been successfully synthesized and applied for hydrogenation of alkynes at room temperature as well as transfer hydrogenation of a number of carbonyl compounds under microwave irradiation conditions. The ...

  1. Exceedingly Fast Oxygen Atom Transfer to Olefins via a Catalytically Competent Nonheme Iron Species.

    Science.gov (United States)

    Serrano-Plana, Joan; Aguinaco, Almudena; Belda, Raquel; García-España, Enrique; Basallote, Manuel G; Company, Anna; Costas, Miquel

    2016-05-17

    The reaction of [Fe(CF3 SO3 )2 (PyNMe3 )] with excess peracetic acid at -40 °C leads to the accumulation of a metastable compound that exists as a pair of electromeric species, [Fe(III) (OOAc)(PyNMe3 )](2+) and [Fe(V) (O)(OAc)(PyNMe3 )](2+) , in fast equilibrium. Stopped-flow UV/Vis analysis confirmed that oxygen atom transfer (OAT) from these electromeric species to olefinic substrates is exceedingly fast, forming epoxides with stereoretention. The impact of the electronic and steric properties of the substrate on the reaction rate could be elucidated, and the relative reactivities determined for the catalytic oxidations could be reproduced by kinetic studies. The observed fast reaction rates and high selectivities demonstrate that this metastable compound is a truly competent OAT intermediate of relevance for nonheme iron catalyzed epoxidations. PMID:27071372

  2. CHARACTERIZATION OF CATALYTIC COMBUSTOR TURBULENCE AND ITS INFLUENCE ON VANE AND ENDWALL HEAT TRANSFER AND ENDWALL FILM COOLING

    Energy Technology Data Exchange (ETDEWEB)

    Forrest E. Ames

    2002-10-01

    Endwall heat transfer distributions taken in a large-scale low speed linear cascade facility are documented for mock catalytic and dry low NOx (DLN) combustion systems. Inlet turbulence levels range from about 1.0 percent for the mock Catalytic combustor condition to 14 percent for the mock dry low NOx combustor system. Stanton number contours are presented at both turbulence conditions for Reynolds numbers based on true chord length and exit conditions ranging from 500,000 to 2,000,000. Catalytic combustor endwall heat transfer shows the influence of the complex three-dimensional flow field, while the effects of individual vortex systems are less evident for the mock dry low NOx cases. Turbulence scales have been documented for both cases. Inlet boundary layers are relatively thin for the mock catalytic combustor case while inlet flow approximates a channel flow with high turbulence for the mock DLN combustor case. Inlet boundary layer parameters are presented across the inlet passage for the three Reynolds numbers and both the mock catalytic and DLN combustor inlet cases. Both midspan and 95 percent span pressure contours are included. This research provides a well-documented database taken across a range of Reynolds numbers and turbulence conditions for assessment of endwall heat transfer predictive capabilities.

  3. Intermolecula transfer and elimination of molecular hydrogen in thermal reactions of unsaturated organic compounds

    Energy Technology Data Exchange (ETDEWEB)

    Suria, S.

    1995-02-10

    Two reactions which are important to coal liquefaction include intermolecular transfer and the elimination of two hydrogen atoms. We have designed several model reactions to probe the viability of several hydrogen transfer and elimination pathways. This report described studies on these reactions using organic model compounds.

  4. Science Letters: Hydrogen transfer reduction of ketones using formic acid as a hydrogen donor under hydrothermal conditions

    Institute of Scientific and Technical Information of China (English)

    Zheng SHEN; Fang-ming JIN; Ya-lei ZHANG; Bing WU; Jiang-lin CAO

    2009-01-01

    The hydrothermal experiments with ketones and formic acid showed that the hydrogen transfer reduction of ketones can be conducted using formic acid as a hydride donor in the presence of NaOH at 300℃. The yield of alcohols was considerably higher at a much lower ratio of hydrogen source to ketones than the traditional Meerwein-Ponndorf-Verley (MPV) reduction,reaching 60% for isopropanol from acetone and 70% for lactic acid from pyruvic acid. Water molecules may act as a catalyst in the hydrogen transfer reduction of ketones under hydrothermal conditions.

  5. Pt nanoparticles modified by rare earth oxides: Electronic effect and influence to catalytic hydrogenation of 3-phenoxybenzaldehyde

    Energy Technology Data Exchange (ETDEWEB)

    Mou, Zhigang; Han, Ming; Li, Gang; Du, Yukou [College of Chemistry, Chemical Engineering and Materials Science, Soochow University, Suzhou 215123 (China); Yang, Ping, E-mail: pyang@suda.edu.cn [College of Chemistry, Chemical Engineering and Materials Science, Soochow University, Suzhou 215123 (China); Zhang, Hailu [Suzhou Institute of Nano-tech and Nano-bionics, Chinese Academy of Sciences, Suzhou 215123 (China); Deng, Zongwu, E-mail: zwdeng2007@sinano.ac.cn [Suzhou Institute of Nano-tech and Nano-bionics, Chinese Academy of Sciences, Suzhou 215123 (China)

    2013-11-15

    Graphical abstract: - Highlights: • The rare earths modified Pt/Al{sub 2}O{sub 3} were prepared by colloidal deposition method. • Modification of Pt by the rare earth enhanced catalytic hydrogenation activity. • The activity improvement is due to electron interaction between Pt and rare earth. • The hydrogenation mechanism of rare earth modified Pt catalyst was proposed. - Abstract: The rare earth elements (La, Ce, Nd, Sm, Pr, and Gd) modified Pt/Al{sub 2}O{sub 3} catalysts were prepared by the colloidal deposition and chemical reduction methods, respectively. Pt nanoparticles with average size 3 ± 0.5 nm were uniformly dispersed on the surface of Al{sub 2}O{sub 3} for the samples prepared by the colloidal deposition method, which exhibited higher activities in the hydrogenation of 3-phenoxybenzadehyde than the corresponding samples prepared by chemical reduction method. Moreover, except Gd, the catalysts modified by rare earth elements showed better catalytic performance than unmodified Pt/Al{sub 2}O{sub 3}. For Pt–Ce/Al{sub 2}O{sub 3} catalyst, when the weight percent of Pt and Ce was 0.5 and 0.25, respectively, the hydrogenation conversion of 3-phenoxybenzaldehyde was 97.3% after 6 h reaction. This activity improvement is due to the electronic interaction between Pt and rare earth elements, which was investigated by X-ray photoelectron spectroscopy.

  6. Pt nanoparticles modified by rare earth oxides: Electronic effect and influence to catalytic hydrogenation of 3-phenoxybenzaldehyde

    International Nuclear Information System (INIS)

    Graphical abstract: - Highlights: • The rare earths modified Pt/Al2O3 were prepared by colloidal deposition method. • Modification of Pt by the rare earth enhanced catalytic hydrogenation activity. • The activity improvement is due to electron interaction between Pt and rare earth. • The hydrogenation mechanism of rare earth modified Pt catalyst was proposed. - Abstract: The rare earth elements (La, Ce, Nd, Sm, Pr, and Gd) modified Pt/Al2O3 catalysts were prepared by the colloidal deposition and chemical reduction methods, respectively. Pt nanoparticles with average size 3 ± 0.5 nm were uniformly dispersed on the surface of Al2O3 for the samples prepared by the colloidal deposition method, which exhibited higher activities in the hydrogenation of 3-phenoxybenzadehyde than the corresponding samples prepared by chemical reduction method. Moreover, except Gd, the catalysts modified by rare earth elements showed better catalytic performance than unmodified Pt/Al2O3. For Pt–Ce/Al2O3 catalyst, when the weight percent of Pt and Ce was 0.5 and 0.25, respectively, the hydrogenation conversion of 3-phenoxybenzaldehyde was 97.3% after 6 h reaction. This activity improvement is due to the electronic interaction between Pt and rare earth elements, which was investigated by X-ray photoelectron spectroscopy

  7. Energy Efficient Catalytic Activation of Hydrogen peroxide for Green Chemical Processes: Final Report

    Energy Technology Data Exchange (ETDEWEB)

    Collins, Terrence J.; Horwitz, Colin

    2004-11-12

    A new, highly energy efficient approach for using catalytic oxidation chemistry in multiple fields of technology has been pursued. The new catalysts, called TAML® activators, catalyze the reactions of hydrogen peroxide and other oxidants for the exceptionally rapid decontamination of noninfectious simulants (B. atrophaeus) of anthrax spores, for the energy efficient decontamination of thiophosphate pesticides, for the facile, low temperature removal of color and organochlorines from pulp and paper mill effluent, for the bleaching of dyes from textile mill effluents, and for the removal of recalcitrant dibenzothiophene compounds from diesel and gasoline fuels. Highlights include the following: 1) A 7-log kill of Bacillus atrophaeus spores has been achieved unambiguously in water under ambient conditions within 15 minutes. 2) The rapid total degradation under ambient conditions of four thiophosphate pesticides and phosphonate degradation intermediates has been achieved on treatment with TAML/peroxide, opening up potential applications of the decontamination system for phosphonate structured chemical warfare agents, for inexpensive, easy to perform degradation of stored and aged pesticide stocks (especially in Africa and Asia), for remediation of polluted sites and water bodies, and for the destruction of chemical warfare agent stockpiles. 3) A mill trial conducted in a Pennsylvanian bleached kraft pulp mill has established that TAML catalyst injected into an alkaline peroxide bleach tower can significantly lower color from the effluent stream promising a new, more cost effective, energy-saving approach for color remediation adding further evidence of the value and diverse engineering capacity of the approach to other field trials conducted on effluent streams as they exit the bleach plant. 4) Dibenzothiophenes (DBTs), including 4,6-dimethyldibenzothiophene, the most recalcitrant sulfur compounds in diesel and gasoline, can be completely removed from model gasoline

  8. A Review of Recent Advances on the Effects of Microstructural Refinement and Nano-Catalytic Additives on the Hydrogen Storage Properties of Metal and Complex Hydrides

    Directory of Open Access Journals (Sweden)

    Jerzy Bystrzycki

    2010-12-01

    Full Text Available The recent advances on the effects of microstructural refinement and various nano-catalytic additives on the hydrogen storage properties of metal and complex hydrides obtained in the last few years in the allied laboratories at the University of Waterloo (Canada and Military University of Technology (Warsaw, Poland are critically reviewed in this paper. The research results indicate that microstructural refinement (particle and grain size induced by ball milling influences quite modestly the hydrogen storage properties of simple metal and complex metal hydrides. On the other hand, the addition of nanometric elemental metals acting as potent catalysts and/or metal halide catalytic precursors brings about profound improvements in the hydrogen absorption/desorption kinetics for simple metal and complex metal hydrides alike. In general, catalytic precursors react with the hydride matrix forming a metal salt and free nanometric or amorphous elemental metals/intermetallics which, in turn, act catalytically. However, these catalysts change only kinetic properties i.e. the hydrogen absorption/desorption rate but they do not change thermodynamics (e.g., enthalpy change of hydrogen sorption reactions. It is shown that a complex metal hydride, LiAlH4, after high energy ball milling with a nanometric Ni metal catalyst and/or MnCl2 catalytic precursor, is able to desorb relatively large quantities of hydrogen at RT, 40 and 80 °C. This kind of behavior is very encouraging for the future development of solid state hydrogen systems.

  9. Microscale Enhancement of Heat and Mass Transfer for Hydrogen Energy Storage

    Energy Technology Data Exchange (ETDEWEB)

    Drost, Kevin [Oregon State Univ., Corvallis, OR (United States); Jovanovic, Goran [Oregon State Univ., Corvallis, OR (United States); Paul, Brian [Oregon State Univ., Corvallis, OR (United States)

    2015-09-30

    The document summarized the technical progress associated with OSU’s involvement in the Hydrogen Storage Engineering Center of Excellence. OSU focused on the development of microscale enhancement technologies for improving heat and mass transfer in automotive hydrogen storage systems. OSU’s key contributions included the development of an extremely compact microchannel combustion system for discharging hydrogen storage systems and a thermal management system for adsorption based hydrogen storage using microchannel cooling (the Modular Adsorption Tank Insert or MATI).

  10. 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

  11. Experimental and Mechanistic Understanding of Aldehyde Hydrogenation Using Au25 Nanoclusters with Lewis Acids: Unique Sites for Catalytic Reactions.

    Science.gov (United States)

    Li, Gao; Abroshan, Hadi; Chen, Yuxiang; Jin, Rongchao; Kim, Hyung J

    2015-11-18

    The catalytic activity of Au25(SR)18 nanoclusters (R = C2H4Ph) for the aldehyde hydrogenation reaction in the presence of a base, e.g., ammonia or pyridine, and transition-metal ions M(z+), such as Cu(+), Cu(2+), Ni(2+) and Co(2+), as a Lewis acid is studied. The addition of a Lewis acid is found to significantly promote the catalytic activity of Au25(SR)18/CeO2 in the hydrogenation of benzaldehyde and a number of its derivatives. Matrix-assisted laser desorption ionization (MALDI) and electrospray ionization (ESI) mass spectrometry in conjunction with UV-vis spectroscopy confirm the generation of new species, Au25-n(SR)18-n (n = 1-4), in the presence of a Lewis acid. The pathways for the speciation of Au24(SR)17 from its parent Au25(SR)18 nanocluster as well as its structure are investigated via the density functional theory (DFT) method. The adsorption of M(z+) onto a thiolate ligand "-SR-" of Au25(SR)18, followed by a stepwise detachment of "-SR-" and a gold atom bonded to "-SR-" (thus an "Au-SR" unit) is found to be the most likely mechanism for the Au24(SR)17 generation. This in turn exposes the Au13-core of Au24(SR)17 to reactants, providing an active site for the catalytic hydrogenation. DFT calculations indicate that M(z+) is also capable of adsorbing onto the Au13-core surface, producing a possible active metal site of a different kind to catalyze the aldehyde hydrogenation reaction. This study suggests, for the first time, that species with an open metal site like adducts [nanoparticle-M]((z-1)+) or fragments Au25-n(SR)18-n function as the catalysts rather than the intact Au25(SR)18. PMID:26498698

  12. Production of hydrogen, liquid fuels, and chemicals from catalytic processing of bio-oils

    Science.gov (United States)

    Huber, George W; Vispute, Tushar P; Routray, Kamalakanta

    2014-06-03

    Disclosed herein is a method of generating hydrogen from a bio-oil, comprising hydrogenating a water-soluble fraction of the bio-oil with hydrogen in the presence of a hydrogenation catalyst, and reforming the water-soluble fraction by aqueous-phase reforming in the presence of a reforming catalyst, wherein hydrogen is generated by the reforming, and the amount of hydrogen generated is greater than that consumed by the hydrogenating. The method can further comprise hydrocracking or hydrotreating a lignin fraction of the bio-oil with hydrogen in the presence of a hydrocracking catalyst wherein the lignin fraction of bio-oil is obtained as a water-insoluble fraction from aqueous extraction of bio-oil. The hydrogen used in the hydrogenating and in the hydrocracking or hydrotreating can be generated by reforming the water-soluble fraction of bio-oil.

  13. Hydrogen transfer in excited pyrrole-ammonia clusters

    Science.gov (United States)

    David, O.; Dedonder-Lardeux, C.; Jouvet, C.; Kang, H.; Martrenchard, S.; Ebata, T.; Sobolewski, A. L.

    2004-06-01

    The excited state hydrogen atom transfer reaction (ESHT) has been studied in pyrrole-ammonia clusters [PyH-(NH3)n+hν→Py•+•NH4(NH3)n-1]. The reaction is clearly evidenced through two-color R2P1 experiments using delayed ionization and presents a threshold around 235 nm (5.3 eV). The cluster dynamics has also been explored by picosecond time scale experiments. The clusters decay in the 10-30 ps range with lifetimes increasing with the cluster size. The appearance times for the reaction products are similar to the decay times of the parent clusters. Evaporation processes are also observed in competition with the reaction, and the cluster lifetime after evaporation is estimated to be around 10 ns. The kinetic energy of the reaction products is fairly large and the energy distribution seems quasi mono kinetic. These experimental results rule out the hypothesis that the reaction proceeds through a direct N-H bond rupture but rather imply the existence of a fairly long-lived intermediate state. Calculations performed at the CASSCF/CASMP2 level confirm the experimental observations, and provide some hints regarding the reaction mechanism.

  14. DESIGN NOTE: A compact catalytic converter for the production of para-hydrogen

    Science.gov (United States)

    Juarez, A. M.; Cubric, D.; King, G. C.

    2002-05-01

    The design and operation of a compact converter to produce a constant flow of para-hydrogen from normal hydrogen is described. The converter features a paramagnetic compound (nickel sulfate) that catalyses the conversion of ortho- to para-hydrogen at temperatures of 14-21 K. The converter has been tested by measuring rotationally resolved photoelectron spectra in the para-hydrogen produced. The percentage of the para-hydrogen species in the converted gas was determined to be >97%.

  15. Hydrogen production from simulated hot coke oven gas by catalytic reforming over Ni/Mg(A1)O catalysts

    Institute of Scientific and Technical Information of China (English)

    Hongwei Cheng; Baohua Yue; Xueguang Wang; Xionggang Lu; Weizhong Ding

    2009-01-01

    Hydrogen production by catalytic reforming of simulated hot coke oven gas (HCOG) with toluene as a model tar compound was investigated in a fixed bed reactor over Ni/Mg(Al)O catalysts. The catalysts were prepared by a homogeneous precipitation method using urea hydrolysis and characterized by ICP,BET, XRD, TPR, TEM and TG. XRD showed that the hydrotalcite type precursor after calcination formed (Ni,Mg)Al2O4 spinel and Ni-Mg-O solid solution structure. TPR results suggested that the increase in Ni/Mg molar ratio gave rise to the decrease in the reduction temperature of Ni2+ to Ni0 on Ni/Mg(Al)O catalysts. The reaction results indicated that toluene and CH4 could completely be converted to H2 and CO in the catalytic reforming of the simulated HCOG under atmospheric pressure and the amount of H2 in the reaction effluent gas was about 4 times more than that in original HCOG. The catalysts with lower Ni/Mg molar ratio showed better catalytic activity and resistance to ceking, which may become promising catalysts in the catalytic reforming of HCOG.

  16. Facultative and partial interspecies hydrogen transfer : competition for reducing equivalents

    OpenAIRE

    Cord-Ruwisch, Ralf; Dubourguier, H.C.

    1986-01-01

    Sulfate reducing bacteria of the genus DESULFOVIBRIO and homoacetogenic bacteria of the genus SPOROMUSA were sensitive to changes of hydrogen concentrations during the growth on an organic substrate. Increase of hydrogen concentrations competitively inhibited the organic substrate degradation and decrease of hydrogen concentration inhibited the respiration and the reduction of the external electron acceptor. Such hydrogen sensitive strains which seem to intermediarily produce and consume hydr...

  17. Slush hydrogen propellant production, transfer, and expulsion studies at the NASA K-Site Facility

    Science.gov (United States)

    Hardy, Terry L.; Whalen, Margaret V.

    1991-01-01

    Slush hydrogen is currently being considered as a fuel for the National Aero-Space Plane (NASP) because it offers the potential for decreased vehicle size and weight. However, no large-scale data was available on the production, transfer, and tank pressure control characteristics required to use the fuel for the NASP. Therefore, experiments were conducted at the NASA Lewis Research Center K-Site Facility to improve the slush hydrogen database. Slush hydrogen was produced using the evaporative cooling, or freeze-thaw, technique in batches of about 800 gallons. This slush hydrogen was pressure transferred to a 5 ft diameter spherical test tank following production, and flow characteristics were measured during this transfer process. The slush hydrogen in the test tank was pressurized and expelled using a pressurized expulsion technique to obtain information on tank pressure control for the NASP. Results from the production, transfer, pressurization, and pressurized expulsion tests are described.

  18. Synthesis, characterization, and reactivity of ruthenium diene/diamine complexes including catalytic hydrogenation of ketones.

    Science.gov (United States)

    Morilla, M Esther; Rodríguez, Pilar; Belderrain, Tomas R; Graiff, Claudia; Tiripicchio, Antonio; Nicasio, M Carmen; Pérez, Pedro J

    2007-10-29

    Thermal reactions between [RuCl2(diene)]n (diene = 2,5-norbornadiene, nbd; 1,5-cyclooctadiene, cod) with an excess of N,N,N',N'-tetramethylethylene diamine (tmeda) afforded derivatives [RuCl2(diene)(tmeda)] (diene = nbd, 1; cod, 2) as a mixture of cis and trans isomers. When thermolysis was performed under H2 mixtures of hydride species [RuCl(H)(diene)(tmeda)] (diene = nbd, 3; cod, 4) and the bis-tmeda adduct trans-[RuCl2(tmeda)2] (5) were obtained in different ratios depending upon the reaction conditions and reaction times. Heating polymeric Ru(II) precursors in toluene in the presence of a 5-fold excess of the bulkier N,N,N',N'-tetraethylethylene diamine (teeda) resulted in a rare diamine dealkylation process with formation of trans-[RuCl2(nbd)(Et2NCH2CH2NHEt)] (6) and trans-[RuCl2(cod)(EtHNCH2CH2NHEt)] (7) in high yields. The presence of N-H functionalities in the coordinated diamine ligands of 6 and 7 was unambiguously established by single-crystal X-ray diffraction studies. The dealkylation process of the teeda ligand seems to proceed intramolecularly as shown by solution NMR studies performed with the soluble Ru(II) precursors trans-[RuCl2(amine)2(diene)] (diene = nbd, amine = morpholine, 9; diene = cod, amine = Et2NH, 10). The above complexes [RuCl2(diene)(diamine)] have been tested as precatalysts in the hydrogenation of ketones both for transfer as well as direct hydrogenation, the latter route being the most effective. PMID:17900107

  19. Pion transfer from hydrogen to deuterium in H2+D2 gas mixtures

    International Nuclear Information System (INIS)

    The transfer of negative pions from pionic hydrogen to deuterium has been investigated in gas mixtures of H2 and D2 as a function of the D2 concentration. The concentration dependence of the transfer rate was fitted using a phenomenological model with two parameters. For C → ∞ (32±3)% of the pions undergo transfer. The fitted parameters reflect the ratio of pion capture to pion transfer in collisions of pionic hydrogen with protons or deuterons. No pressure dependence for pion transfer was found. (Author) 33 refs., 3 tabs., 7 figs

  20. Cellular graphene aerogel combines ultralow weight and high mechanical strength: A highly efficient reactor for catalytic hydrogenation

    Science.gov (United States)

    Zhang, Bingxing; Zhang, Jianling; Sang, Xinxin; Liu, Chengcheng; Luo, Tian; Peng, Li; Han, Buxing; Tan, Xiuniang; Ma, Xue; Wang, Dong; Zhao, Ning

    2016-05-01

    The construction of three-dimensional graphene aerogels (GAs) is of great importance owing to their outstanding properties for various applications. Up to now, the combination of ultralow weight and super mechanical strength for GA remains a great challenge. Here we demonstrate the fabrication of cellular GAs by a facile, easily controlled and versatile route, i.e. the chemical reduction of graphene oxide assemblies at oil-water interface under a mild condition (70 °C). The GA is ultralight (with density resilient because the walls of the cell closely pack in a highly ordered manner to maximize mechanical strength. The GA has been utilized as an appealing reactor for catalytic hydrogenation, which exhibited great advantages such as large oil absorption capability, exceptional catalytic activity, ease of product separation and high stability.

  1. Cellular graphene aerogel combines ultralow weight and high mechanical strength: A highly efficient reactor for catalytic hydrogenation

    Science.gov (United States)

    Zhang, Bingxing; Zhang, Jianling; Sang, Xinxin; Liu, Chengcheng; Luo, Tian; Peng, Li; Han, Buxing; Tan, Xiuniang; Ma, Xue; Wang, Dong; Zhao, Ning

    2016-01-01

    The construction of three-dimensional graphene aerogels (GAs) is of great importance owing to their outstanding properties for various applications. Up to now, the combination of ultralow weight and super mechanical strength for GA remains a great challenge. Here we demonstrate the fabrication of cellular GAs by a facile, easily controlled and versatile route, i.e. the chemical reduction of graphene oxide assemblies at oil-water interface under a mild condition (70 °C). The GA is ultralight (with density <3 mg cm−3) yet mechanically resilient because the walls of the cell closely pack in a highly ordered manner to maximize mechanical strength. The GA has been utilized as an appealing reactor for catalytic hydrogenation, which exhibited great advantages such as large oil absorption capability, exceptional catalytic activity, ease of product separation and high stability. PMID:27174450

  2. Cellular graphene aerogel combines ultralow weight and high mechanical strength: A highly efficient reactor for catalytic hydrogenation.

    Science.gov (United States)

    Zhang, Bingxing; Zhang, Jianling; Sang, Xinxin; Liu, Chengcheng; Luo, Tian; Peng, Li; Han, Buxing; Tan, Xiuniang; Ma, Xue; Wang, Dong; Zhao, Ning

    2016-01-01

    The construction of three-dimensional graphene aerogels (GAs) is of great importance owing to their outstanding properties for various applications. Up to now, the combination of ultralow weight and super mechanical strength for GA remains a great challenge. Here we demonstrate the fabrication of cellular GAs by a facile, easily controlled and versatile route, i.e. the chemical reduction of graphene oxide assemblies at oil-water interface under a mild condition (70 °C). The GA is ultralight (with density <3 mg cm(-3)) yet mechanically resilient because the walls of the cell closely pack in a highly ordered manner to maximize mechanical strength. The GA has been utilized as an appealing reactor for catalytic hydrogenation, which exhibited great advantages such as large oil absorption capability, exceptional catalytic activity, ease of product separation and high stability. PMID:27174450

  3. Catalytic Hydrolysis of Ammonia Borane by Cobalt Nickel Nanoparticles Supported on Reduced Graphene Oxide for Hydrogen Generation

    Directory of Open Access Journals (Sweden)

    Yuwen Yang

    2014-01-01

    Full Text Available Well dispersed magnetically recyclable bimetallic CoNi nanoparticles (NPs supported on the reduced graphene oxide (RGO were synthesized by one-step in situ coreduction of aqueous solution of cobalt(II chloride, nickel (II chloride, and graphite oxide (GO with ammonia borane (AB as the reducing agent under ambient condition. The CoNi/RGO NPs exhibits excellent catalytic activity with a total turnover frequency (TOF value of 19.54 mol H2 mol catalyst−1 min−1 and a low activation energy value of 39.89 kJ mol−1 at room temperature. Additionally, the RGO supported CoNi NPs exhibit much higher catalytic activity than the monometallic and RGO-free CoNi counterparts. Moreover, the as-prepared catalysts exert satisfying durable stability and magnetically recyclability for the hydrolytic dehydrogenation of AB, which make the practical reusing application of the catalysts more convenient. The usage of the low-cost, easy-getting catalyst to realize the production of hydrogen under mild condition gives more confidence for the application of ammonia borane as a hydrogen storage material. Hence, this general method indicates that AB can be used as both a potential hydrogen storage material and an efficient reducing agent, and can be easily extended to facile preparation of other RGO-based metallic systems.

  4. Numerical Radiative Transfer and the Hydrogen Reionization of the Universe

    Science.gov (United States)

    Petkova, M.

    2011-03-01

    ) simulation code GADGET. It is based on a fast, robust and photon-conserving integration scheme where the radiation transport problem is approximated in terms of moments of the transfer equation and by using a variable Eddington tensor as a closure relation, following the "OTVET"-suggestion of Gnedin & Abel. We derive a suitable anisotropic diffusion operator for use in the SPH discretization of the local photon transport, and we combine this with an implicit solver that guarantees robustness and photon conservation. This entails a matrix inversion problem of a huge, sparsely populated matrix that is distributed in memory in our parallel code. We solve this task iteratively with a conjugate gradient scheme. Finally, to model photon sink processes we consider ionization and recombination processes of hydrogen, which is represented with a chemical network that is evolved with an implicit time integration scheme. We present several tests of our implementation, including single and multiple sources in static uniform density fields with and without temperature evolution, shadowing by a dense clump, and multiple sources in a static cosmological density field. All tests agree quite well with analytical computations or with predictions from other radiative transfer codes, except for shadowing. However, unlike most other radiative transfer codes presently in use for studying reionization, our new method can be used on-the-fly during dynamical cosmological simulations, allowing simultaneous treatments of galaxy formation and the reionization process of the Universe. We carry out hydrodynamical simulations of galaxy formation that simultaneously follow radiative transfer of hydrogen-ionizing photons, based on the optically-thin variable Eddington tensor approximation as implemented in the GADGET code. We consider only star-forming galaxies as sources and examine to what extent they can yield a reasonable reionization history and thermal state of the intergalactic medium at redshifts

  5. Chemiluminescence and chemiluminescence resonance energy transfer (CRET) aptamer sensors using catalytic hemin/G-quadruplexes.

    Science.gov (United States)

    Liu, Xiaoqing; Freeman, Ronit; Golub, Eyal; Willner, Itamar

    2011-09-27

    The incorporation of hemin into the thrombin/G-quadruplex aptamer assembly or into the ATP/G-quadruplex nanostructure yields active DNAzymes that catalyze the generation of chemiluminescence. These catalytic processes enable the detection of thrombin and ATP with detection limits corresponding to 200 pM and 10 μM, respectively. The conjugation of the antithrombin or anti-ATP aptamers to CdSe/ZnS semiconductor quantum dots (QDs) allowed the detection of thrombin or ATP through the luminescence of the QDs that is powered by a chemiluminescence resonance energy-transfer (CRET) process stimulated by the hemin/G-quadruplex/thrombin complex or the hemin/G-quadruplex/ATP nanostructure, in the presence of luminol/H(2)O(2). The advantages of applying the CRET process for the detection of thrombin or ATP, by the resulting hemin/G-quadruplex DNAzyme structures, are reflected by low background signals and the possibility to develop multiplexed aptasensor assays using different sized QDs. PMID:21866963

  6. Catalytic steam gasification of biomass for a sustainable hydrogen future: influence of catalyst composition

    OpenAIRE

    Wu, C.; Wang, Z.; Wang, L.; J. Huang; Williams, PT

    2014-01-01

    Hydrogen is regarded as a clean energy for fuelling the future. Hydrogen will be the energy carrier from other resources such as hydropower, wind, solar and biomass. Producing hydrogen from gasification of biomass wastes, particularly in the presence of steam, represents a promising route to produce this clean and CO2-neutral fuel. The steam pyrolysis-gasification ofbiomass (wood sawdust) was carried out with various nickel-based catalysts for hydrogen production in a two-stage fixed bed reac...

  7. Simple and rapid hydrogenation of p-nitrophenol with aqueous formic acid in catalytic flow reactors

    OpenAIRE

    Rahat Javaid; Shin-ichiro Kawasaki; Akira Suzuki; Suzuki, Toshishige M

    2013-01-01

    The inner surface of a metallic tube (i.d. 0.5 mm) was coated with a palladium (Pd)-based thin metallic layer by flow electroless plating. Simultaneous plating of Pd and silver (Ag) from their electroless-plating solution produced a mixed distributed bimetallic layer. Preferential acid leaching of Ag from the Pd–Ag layer produced a porous Pd surface. Hydrogenation of p-nitrophenol was examined in the presence of formic acid simply by passing the reaction solution through the catalytic tubular...

  8. 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.

  9. Schwinger variational calculation of ionization of hydrogen atoms for large momentum transfers

    Indian Academy of Sciences (India)

    K Chakrabarti

    2002-03-01

    Schwinger variational principle is used here to study large momentum transfer cases of electron and positron impact ionization of atomic hydrogen from the ground state at intermediate and moderately high energies. The results appear somewhat better compared to other theories.

  10. Passive auto-catalytic recombiners operation in the presence of hydrogen and carbon monoxide: Experimental study and model development

    International Nuclear Information System (INIS)

    Highlights: • We studied the hydrogen conversion in the presence of carbon monoxide (CO). • CO recombines at a lower efficiency than hydrogen. • Under the given conditions, hydrogen conversion is not affected by CO. • We used three different numerical codes to simulate the experimental findings. • All codes are reproducing the experimental data well. -- Abstract: In a LWR severe accident, carbon monoxide (CO) may be generated inside the containment due to molten corium concrete interaction (MCCI). As a component of the accident atmosphere, CO will interact with passive auto-catalytic recombiners (PARs) which are installed inside LWR containments for hydrogen (H2) removal. Depending on the boundary conditions, CO may either react with oxygen to carbon dioxide (CO2) or act as catalyst poison, reducing the catalyst activity and hence the hydrogen conversion efficiency. A new experimental test programme performed in co-operation between JÜLICH and RWTH investigates these aspects aiming at providing data for model development for advanced severe accident analyses. In the first test series presented here, the parallel catalytic reaction of H2 and CO on the catalyst surface has been studied, i.e. the hydrogen recombination reaction was started before CO was injected. In total, 33 steady state measurements have been performed. The test series was jointly evaluated by JÜLICH, RWTH and IRSN. The test results show that under the given conditions the conversion of CO into CO2 has no negative impact on the parallel hydrogen conversion. The efficiency of the CO recombination in terms of molar rates is significantly smaller (by a factor of ∼2) than the corresponding H2 conversion efficiency. Due to the exothermal reaction, the parallel CO conversion may also have an impact on the possible ignition of the flammable gases at hot PAR surfaces. The authors have used three different numerical codes for the simulation of the parallel CO/H2 recombination. The codes REKO

  11. A compact process for the treatment of olive mill wastewater by combining wet hydrogen peroxide catalytic oxidation and biological techniques

    International Nuclear Information System (INIS)

    A system based on combined actions of catalytic wet oxidation and microbial technologies for the treatment of highly polluted OMW containing polyphenols was studied. The wet hydrogen peroxide catalytic oxidation (WHPCO) process has been investigated in the semi-batch mode at atmospheric pressure, using aluminium-iron-pillared inter layer clay ((Al-Fe)PILC), under two different catalytic processes: ((Al-Fe)PILC/H2O2/ultraviolet radiations) at 25 deg. C and ((Al-Fe)PILC/H2O2) at 50 deg. C. The results show that raw OMW was resistant to the photocatalytic process. However ((Al-Fe)PILC/H2O2), system operating at 50 deg. C reduced considerably the COD, colour and total phenolic contents, and thus decreased the inhibition of the marine photobacteria Vibrio fischeri luminescence by 70%. This study also examined the feasibility of coupling WHPCO and anaerobic digestion treatment. Biomethanisation experiments performed with raw OMW or pre-treated OMW proved that pre-treatments with ((Al-Fe)PILC/H2O2) system, for more than 2 h, resulted in higher methane production. Both untreated OMW as well as 2-h pre-treated OMW revealed as toxic to anaerobic bacteria.

  12. A compact process for the treatment of olive mill wastewater by combining wet hydrogen peroxide catalytic oxidation and biological techniques

    Energy Technology Data Exchange (ETDEWEB)

    Azabou, Samia [Laboratoire des BioProcedes, Centre de Biotechnologie de Sfax, BP 1177, 3018 Sfax (Tunisia); Najjar, Wahiba [Laboratoire de Chimie des Materiaux et Catalyse, Faculte des Sciences de Tunis, Campus Universitaire, 2092 Tunis (Tunisia); Bouaziz, Mohamed [Laboratoire des BioProcedes, Centre de Biotechnologie de Sfax, BP 1177, 3018 Sfax (Tunisia); Ghorbel, Abdelhamid [Laboratoire de Chimie des Materiaux et Catalyse, Faculte des Sciences de Tunis, Campus Universitaire, 2092 Tunis (Tunisia); Sayadi, Sami, E-mail: sami.sayadi@cbs.rnrt.tn [Laboratoire des BioProcedes, Centre de Biotechnologie de Sfax, BP 1177, 3018 Sfax (Tunisia)

    2010-11-15

    A system based on combined actions of catalytic wet oxidation and microbial technologies for the treatment of highly polluted OMW containing polyphenols was studied. The wet hydrogen peroxide catalytic oxidation (WHPCO) process has been investigated in the semi-batch mode at atmospheric pressure, using aluminium-iron-pillared inter layer clay ((Al-Fe)PILC), under two different catalytic processes: ((Al-Fe)PILC/H{sub 2}O{sub 2}/ultraviolet radiations) at 25 deg. C and ((Al-Fe)PILC/H{sub 2}O{sub 2}) at 50 deg. C. The results show that raw OMW was resistant to the photocatalytic process. However ((Al-Fe)PILC/H{sub 2}O{sub 2}), system operating at 50 deg. C reduced considerably the COD, colour and total phenolic contents, and thus decreased the inhibition of the marine photobacteria Vibrio fischeri luminescence by 70%. This study also examined the feasibility of coupling WHPCO and anaerobic digestion treatment. Biomethanisation experiments performed with raw OMW or pre-treated OMW proved that pre-treatments with ((Al-Fe)PILC/H{sub 2}O{sub 2}) system, for more than 2 h, resulted in higher methane production. Both untreated OMW as well as 2-h pre-treated OMW revealed as toxic to anaerobic bacteria.

  13. Mapping the Hydrogen Bond Networks in the Catalytic Subunit of Protein Kinase A Using H/D Fractionation Factors.

    Science.gov (United States)

    Li, Geoffrey C; Srivastava, Atul K; Kim, Jonggul; Taylor, Susan S; Veglia, Gianluigi

    2015-07-01

    Protein kinase A is a prototypical phosphoryl transferase, sharing its catalytic core (PKA-C) with the entire kinase family. PKA-C substrate recognition, active site organization, and product release depend on the enzyme's conformational transitions from the open to the closed state, which regulate its allosteric cooperativity. Here, we used equilibrium nuclear magnetic resonance hydrogen/deuterium (H/D) fractionation factors (φ) to probe the changes in the strength of hydrogen bonds within the kinase upon binding the nucleotide and a pseudosubstrate peptide (PKI5-24). We found that the φ values decrease upon binding both ligands, suggesting that the overall hydrogen bond networks in both the small and large lobes of PKA-C become stronger. However, we observed several important exceptions, with residues displaying higher φ values upon ligand binding. Notably, the changes in φ values are not localized near the ligand binding pockets; rather, they are radiated throughout the entire enzyme. We conclude that, upon ligand and pseudosubstrate binding, the hydrogen bond networks undergo extensive reorganization, revealing that the open-to-closed transitions require global rearrangements of the internal forces that stabilize the enzyme's fold. PMID:26030372

  14. Characterization of Porphyrin-Co(III)-'Nitrene Radical' Species Relevant in Catalytic Nitrene Transfer Reactions.

    Science.gov (United States)

    Goswami, Monalisa; Lyaskovskyy, Volodymyr; Domingos, Sérgio R; Buma, Wybren Jan; Woutersen, Sander; Troeppner, Oliver; Ivanović-Burmazović, Ivana; Lu, Hongjian; Cui, Xin; Zhang, X Peter; Reijerse, Edward J; DeBeer, Serena; van Schooneveld, Matti M; Pfaff, Florian Felix; Ray, Kallol; de Bruin, Bas

    2015-04-29

    mono-nitrene case remains elusive, but some plausible candidates are NH3, NH2(-), NsNH(-), and OH(-); NsNH(-) being the most plausible. Conversion of mono-nitrene species 3(P1)(Ns) into bis-nitrene species 5(P1)(Ns) upon reaction with 4(Ns) was demonstrated. Solutions containing 3(P1)(Ns) and 5(P1)(Ns) proved to be still active in catalytic aziridination of styrene, consistent with their proposed key involvement in nitrene transfer reactions mediated by cobalt(II) porphyrins. PMID:25844713

  15. Activation and deactivation of a robust immobilized Cp*Ir-transfer hydrogenation catalyst: a multielement in situ X-ray absorption spectroscopy study.

    Science.gov (United States)

    Sherborne, Grant J; Chapman, Michael R; Blacker, A John; Bourne, Richard A; Chamberlain, Thomas W; Crossley, Benjamin D; Lucas, Stephanie J; McGowan, Patrick C; Newton, Mark A; Screen, Thomas E O; Thompson, Paul; Willans, Charlotte E; Nguyen, Bao N

    2015-04-01

    A highly robust immobilized [Cp*IrCl2]2 precatalyst on Wang resin for transfer hydrogenation, which can be recycled up to 30 times, was studied using a novel combination of X-ray absorption spectroscopy (XAS) at Ir L3-edge, Cl K-edge, and K K-edge. These culminate in in situ XAS experiments that link structural changes of the Ir complex with its catalytic activity and its deactivation. Mercury poisoning and "hot filtration" experiments ruled out leached Ir as the active catalyst. Spectroscopic evidence indicates the exchange of one chloride ligand with an alkoxide to generate the active precatalyst. The exchange of the second chloride ligand, however, leads to a potassium alkoxide-iridate species as the deactivated form of this immobilized catalyst. These findings could be widely applicable to the many homogeneous transfer hydrogenation catalysts with Cp*IrCl substructure. PMID:25768298

  16. Applicability of heat transfer equations to hydrogen combustion

    OpenAIRE

    Shudo, Toshio; Suzuki, Hiroyuki

    2002-01-01

    Previous research by the authors showed that hydrogen combustion exhibits a higher cooling loss to the combustion chamber wall of an internal combustion engine compared to hydrocarbon combustion because of its higher burning velocity and shorter quenching distance. The high cooling loss means that reduction of the cooling loss is essential to establish a high thermal efficiency in hydrogen combustion engines. This research analyzed the applicability of equations to describe the h...

  17. Study on 1 GW class hybrid energy transfer line of hydrogen and electricity

    International Nuclear Information System (INIS)

    Applicability of 1 GW class hybrid energy transfer line of hydrogen and electricity is investigated. Target distance of hybrid energy transfer line is 1000 km. Hydrogen refrigeration station is placed on every 10 km of the unit section. The rated current and withstand voltage of the dc power line are 10 kA and 100 kV, respectively. Capacity of the liquid hydrogen transportation is 100 tons per day. Transfer line consists of the superconducting (SC) cable, space for liquid hydrogen, electrical insulation layer, vacuum space for thermal insulation, and cryogenic envelopes. High Jc performance in a liquid hydrogen temperature requires for the SC cable. The MgB2 wire is one of the potential candidates for this system as well as BSCCO or YBCO tapes. To keep the liquid state of hydrogen anywhere in the unit section, the temperature and pressure of the inlet point were selected to 17 K and 0.4 MPa, respectively. When the heat leak into the liquid hydrogen was 1.0 W/m (expected value), the temperature at the outlet became 18.1 K. Total power consumption of the 10 kW class refrigerator is estimated to 660 kW. The total power consumption for the hybrid energy transfer line of 1000 km length becomes 132 MW. This value is equivalent to 13.2 % to the transport capacity of 1GW

  18. Heat transfer comparison between methane and hydrogen in a spark ignited engine

    Energy Technology Data Exchange (ETDEWEB)

    Sierens, Roger; Demuynck, Joachim; Paepe, Michel de; Verhelst, Sebastian [Ghent Univ. (Belgium)

    2010-07-01

    Hydrogen is one of the alternative fuels which are being investigated at Ghent University. NO{sub x} emissions will occur at high engine loads and they are a constraint for power and efficiency optimization. The formation of NO{sub x} emissions is temperature dependent. Consequently, the heat transfer from the burning gases to the cylinder walls has to be accurately modelled if precise computer calculations of the emissions are wanted. Several engine heat transfer models exist but they have been cited to be inaccurate for hydrogen. We have measured the heat flux in a spark ignited engine with a commercially available heat flux sensor. This paper investigates the difference between the heat transfer of hydrogen and a fossil fuel, in this case methane. Measurements with the same indicated power output are compared and the effect of the heat loss on the indicated efficiency is investigated. The power output of hydrogen combustion is lowered by burning lean in contrast to using a throttle in the case of methane. Although the peak in the heat flux of hydrogen is 3 times higher compared to methane for a high engine power output, the indicated efficiency is only 3% lower. The heat loss for hydrogen at a low engine load is smaller than that of methane which results in a higher indicated efficiency. The richness of the hydrogen-air mixture has a great influence on the heat transfer process in contrast to the in-cylinder mass in the case of methane. (orig.)

  19. Theoretical analysis of intramolecular double-hydrogen transfer in bridged-ring compounds

    Science.gov (United States)

    Smedarchina, Zorka K.; Siebrand, Willem

    1993-08-01

    Model calculations are reported on double-hydrogen and double-deuterium transfer rates in two bridged-ring molecules recently investigated by Mackenzie. [Tetrahedron Letters, 33 (1992) 5629]. The calculations indicate that, contrary to an earlier interpretation, the two atoms are transferred by asynchronous tunnelling, the observed activation energy being representative of the energy of the biradical intermediate rather than the barrier height.

  20. Height of transfer unit determination at hydrogen isotopic distillation on structured packing, B7 type

    International Nuclear Information System (INIS)

    Due to the low pressure drop that it introduces, the structured packing is often used in the case of distillations under vacuum and of the mixture separation when the desired component is founded in very low concentration, for example the water, hydrogen and oxygen isotopic distillation. The paper presents a model for the determination of height of transfer unit at hydrogen isotopic distillation plant with structured B7 type packing. The values of the height of a transfer unit (HTU) calculated with the analogy model between the heat, momentum and mass transfer are compared with the experimental data

  1. Plasma power source based on a catalytic reaction of atomic hydrogen measured by water bath calorimetry

    International Nuclear Information System (INIS)

    Extreme ultraviolet (EUV) spectroscopy was recorded on microwave discharges of helium with 2% hydrogen. Novel emission lines were observed with energies of q x 13.6 eV, where q=1, 2, 3, 4, 6, 7, 8, 9, 11 or these discrete energies less 21.2 eV corresponding to inelastic scattering of these photons by helium atoms due to excitation of He (1s2) to He (1s12p1). The average hydrogen atom temperature was measured to be 180-210 eV versus ∼3 eV for pure hydrogen. The electron temperature Te for helium-hydrogen was 30,500±5% K compared to 7400±5% K for pure helium. Dominant He+ emission and an intensification of the plasma emission observed when He+ was present with atomic hydrogen demonstrated the role of He+ as a catalyst. Using water bath calorimetry, excess power was observed from the helium-hydrogen plasma compared to control krypton plasma. For example, for an input of 8.1 W, the total plasma power of the helium-hydrogen plasma measured by water bath calorimetry was 30.0 W corresponding to 21.9 W of excess power in 3 cm3. The excess power density and energy balance were high, 7.3 W/cm3 and -2.9x104 kJ/mole H2, respectively

  2. Role of bonding mechanisms during transfer hydrogenation reaction on heterogeneous catalysts of platinum nanoparticles supported on zinc oxide nanorods

    Science.gov (United States)

    Al-Alawi, Reem A.; Laxman, Karthik; Dastgir, Sarim; Dutta, Joydeep

    2016-07-01

    For supported heterogeneous catalysis, the interface between a metal nanoparticle and the support plays an important role. In this work the dependency of the catalytic efficiency on the bonding chemistry of platinum nanoparticles supported on zinc oxide (ZnO) nanorods is studied. Platinum nanoparticles were deposited on ZnO nanorods (ZnO NR) using thermal and photochemical processes and the effects on the size, distribution, density and chemical state of the metal nanoparticles upon the catalytic activities are presented. The obtained results indicate that the bonding at Pt-ZnO interface depends on the deposition scheme which can be utilized to modulate the surface chemistry and thus the activity of the supported catalysts. Additionally, uniform distribution of metal on the catalyst support was observed to be more important than the loading density. It is also found that oxidized platinum Pt(IV) (platinum hydroxide) provided a more suitable surface for enhancing the transfer hydrogenation reaction of cyclohexanone with isopropanol compared to zero valent platinum. Photochemically synthesized ZnO supported nanocatalysts were efficient and potentially viable for upscaling to industrial applications.

  3. Effects of acido-basic support properties on the catalytic hydrogenation of acetylene on gold nano-particles

    Science.gov (United States)

    Manda, Abdullah Ahmed

    Metallic gold nanoparticles supported on gamma-Al2O 3 and magnesia-alumina mixed oxide, with different magnesia content have been prepared by sol-gel method and characterized by different techniques (inductive coupled plasma-mass spectroscopy (ICP-MS), XRD, BET surface area analysis, transmission electron microscopy (TEM), CO2 and NH 3 temperature programmed desorption (TPD), H2 temperature programmed reduction (TPR) and FTIR of adsorbed CO2). Such systems were found to produce catalysts with controllable acidity, varying from catalyst possessing large density of acidic and low density of basic sites, others with acidic and basic sites of equal strength and density, and others with large basic and low acid sites densities, respectively. The catalytic assessment of the generated acidity was carried out using 2-propanol decomposition as a test reaction. The results obtained indicate that the presence of magnesia and reduced gold nanopartilces has imparted the catalysts, 1%Au/4%Mg-Al 2O3 and 1%Au/8%Mg-Al2O3, with significant base-catalytic properties. Acetylene hydrogenation and formation of coke deposits were investigated on a gold catalyst supported on gamma-Al2O3 and gold supported on alumina-magnisia mixed oxide with different gold content; 1%Au/gamma-Al 2O3, 1%Au/15%Mg-Al2O3, 2%Au/15%Mg-Al 2O3 and 4%Au/15%Mg-Al2O3. The effect of the H2/C2H2 ratio was studied over a range of values. The catalytic activity and selectivity towards ethylene and other products were investigated at different reaction temperatures. Acetylene hydrogenation was investigated in the presence and absence of ethylene in stream. It is investigated that the adsorption of the triple bond is preferred over the double bond and during selective catalytic (SCR) of C2H2 the two hydrocarbons do not compete for the same adsorption sites. The deactivation of catalysts was studied by temperature programmed oxidation (TPO). Higher content of coke over 1%Au/Al2O3 catalyst was investigated in contrast to

  4. Muon transfer from muonic hydrogen to heavier atoms; Transfert de charge muonique

    Energy Technology Data Exchange (ETDEWEB)

    Dupays, A

    2004-06-01

    This work concerns muon transfer from muonic hydrogen to heavier atoms. Recently, a method of measurement of the hyperfine structure of ground-state muonic hydrogen based on the collision energy dependence of the muon transfer rate to oxygen has been proposed. This proposal is based on measurements which where performed at the Paul Scherrer Institute in the early nineties which indicate that the muon transfer from muonic hydrogen to oxygen increases by a factor of 4 going from thermal to 0.12 eV energies. The motivation of our calculations was to confirm this behaviour. To study the collision energy dependence of the muon transfer rate, we have used a time-independent close-coupling method. We have set up an hyperspherical elliptic formalism valid for nonzero total angular momentum which allows accurate computations of state-to-state reactive and charge exchange processes. We have applied this formalism to muon-transfer process to oxygen and neon. The comparison with experimental results is in both cases excellent. Finally, the neon transfer rate dependence with energy suggests to use neon instead of oxygen to perform a measurement of the hyperfine structure of muonic hydrogen. The results of accurate calculations of the muon transfer rates from muonic protium and deuterium atoms to nitrogen, oxygen and neon are also reported. Very good agreement with measured rates is obtained and for the three systems, the isotopic effect is perfectly reproduced. (author)

  5. 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.

  6. H2CAP - Hydrogen assisted catalytic biomass pyrolysis for green fuels

    DEFF Research Database (Denmark)

    Arndal, Trine Marie Hartmann; Høj, Martin; Jensen, Peter Arendt;

    2014-01-01

    Pyrolysis of biomass produces a high yield of condensable oil at moderate temperature and low pressure.This bio-oil has adverse properties such as high oxygen and water contents, high acidity and immiscibility with fossil hydrocarbons. Catalytic hydrodeoxygenation (HDO) is a promising technology...... that can be used to upgrade the crude bio-oil to fuel-grade oil. The development of the HDO process is challenged by rapid catalyst deactivation, instability of the pyrolysis oil, poorly investigated reaction conditions and a high complexity and variability of the input oil composition. However......, continuous catalytic hydropyrolysis coupled with downstream HDO of the pyrolysis vapors before condensation shows promise (Figure 1). A bench scale experimental setup will be constructed for the continuous conversion of solid biomass (100g /h) to low oxygen, fuel-grade bio-oil. The aim is to provide a proof...

  7. Combustion of hydrogen-air in micro combustors with catalytic Pt layer

    International Nuclear Information System (INIS)

    Micro power generators have high power density. However, their key components micro combustors have low stability. In this experiment, catalyst is applied to improve the stability. The catalytic micro combustor is made from an alumina ceramic tube. It has inner diameter of 1 mm, outer diameter of 2.02 mm and length of 24.5 mm. It is prepared through impregnation of aqueous solution of H2PtCl6. The flammability limits and surface temperatures under different operation conditions are measured. The flow rates range from 0.08 to 0.4 L/min. According to the experimental results, catalyst is effective to inhibit extinction. For example, At 0.8 L/min, the stability limit is 0.193-14.9 in the non-catalytic combustor. After applying catalyst, the lean limit is near 0, and the rich limit is 29.3. But catalyst is less effective to inhibit blow out. Increasing flow rates also inhibits extinction. In the non-catalytic combustor, while the flow rates increase from 0.08 to 0.2 L/min, the lean stability limit decreases from 0.193 to 0.125. The experimental results indicate that catalyst induces shift downstream in the stoichiometric and rich cases. The numeric simulation verifies that the heterogeneous reaction weakens the homogeneous reaction through consuming fuels. Thus, the insufficient heat recirculation makes the reaction region shift downstream. However, lean mixture has intense reaction in the catalytic combustor. It is attributed to the high mass diffusion and low thermal diffusion of lean mixture.

  8. Size Control of Iron Oxide Nanoparticles Using Reverse Microemulsion Method: Morphology, Reduction, and Catalytic Activity in CO Hydrogenation

    Directory of Open Access Journals (Sweden)

    Mohammad Reza Housaindokht

    2013-01-01

    Full Text Available Iron oxide nanoparticles were prepared by microemulsion method and evaluated in Fischer-Tropsch synthesis. The precipitation process was performed in a single-phase microemulsion operating region. Different HLB values of surfactant were prepared by mixing of sodium dodecyl sulfate (SDS and Triton X-100. Transmission electron microscopy (TEM, surface area, pore volume, average pore diameter, pore size distribution, and XRD patterns were used to analyze size distribution, shape, and structure of precipitated hematite nanoparticles. Furthermore, temperature programmed reduction (TPR and catalytic activity in CO hydrogenation were implemented to assess the performance of the samples. It was found that methane and CO2 selectivity and also the syngas conversion increased as the HLB value of surfactant decreased. In addition, the selectivity to heavy hydrocarbons and chain growth probability (α decreased by decreasing the catalyst crystal size.

  9. Effect of hydrogen combustion reaction on the dehydrogenation of ethane in a fixed-bed catalytic membrane reactor

    Institute of Scientific and Technical Information of China (English)

    Masoud Hasany; Mohammad Malakootikhah; Vahid Rahmanian; Soheila Yaghmaei

    2015-01-01

    A two-dimensional non-isothermal mathematical model has been developed for the ethane dehydrogenation reaction in a fixed-bed catalytic membrane reactor. Since ethane dehydrogenation is an equilibrium reaction, removal of produced hydrogen by the membrane shifts the thermodynamic equilibrium to ethylene production. For further displacement of the dehydrogenation reaction, oxidative dehydrogenation method has been used. Since ethane dehydrogenation is an endothermic reaction, the energy produced by the oxidative dehydrogena-tion method is consumed by the dehydrogenation reaction. The results show that the oxidative dehydrogenation method generated a substantial improvement in the reactor performance in terms of high conversions and significant energy saving. It was also established that the sweep gas velocity in the shell side of the reactor is one of the most important factors in the effectiveness of the reactor.

  10. Synthesis and Catalytic Performance of Ni/SiO2 for Hydrogenation of 2-Methylfuran to 2-Methyltetrahydrofuran

    Directory of Open Access Journals (Sweden)

    Fu Ding

    2015-01-01

    Full Text Available A series of Ni/SiO2 catalysts with different Ni content were prepared by sol-gel method for application in the synthesis of 2-methyltetrahydrofuran (2-MTHF by hydrogenation of 2-methylfuran (2-MF. The catalyst structure was investigated by X-ray diffraction (XRD, transmission electron microscopy (TEM, X-ray photoelectron spectroscopy (XPS, and temperature programmed reduction (TPR. It is found that structures and catalytic performance of the catalysts were highly affected by the Ni content. The catalyst with a 25% Ni content had an appropriate size of the Ni species and larger BET surface area and produced a higher 2-MF conversion with enhanced selectivity in 2-MTHF.

  11. Preparation and Characterization of A New Dinuclear Ruthenium Complex with BDPX Ligand and Its Catalytic Hydrogenation Reactions for Cinnamaldehyde

    Institute of Scientific and Technical Information of China (English)

    TANG,Yuan-You(唐元友); LI,Rui-Xiang(李瑞祥); LI,Xian-Jun(李贤均); WONG,Ning-Bew(黄宁表); TIN,Kim-Chung(田金忠); ZHANG,Zhe-Ying(张哲英); MAK,Thomas C.W.(麦松威)

    2004-01-01

    A new anionic dinuclear ruthenium complex bearing 1,2-bis(diphenylphosphinomethyl)benzene (BDPX)[NH2Et2][{RuCl (BDPX)}2(μ-Cl)3] (1) was synthesized and its structure was determined by an X-ray crystallographic analysis. This result indicated that complex 1 consisted of an anion dinuclear BDPX-Ru and a cationic diethylammonium. The crystal belonged to monoclinic system, C2/c space group with a=3.3552(7) nm, b= 1.8448(4)nm, c=2.4265(5) nm, β= 101.89(3)° and Z=8. The catalytic hydrogenation activities and selectivities of complex 1 for cinnamaldehyde were investigated.

  12. Oxygen assisted reconstructions of rhodium and platinum nanocrystals and their effects on local catalytic activity of hydrogenation reactions

    Science.gov (United States)

    Barroo, C.; Gilis, N.; Lambeets, S. V.; Devred, F.; Visart de Bocarmé, T.

    2014-06-01

    The reconstruction of rhodium and platinum crystals of some tens of nanometres diameter was investigated during the ongoing hydrogenation of oxygen atoms resulting from the dissociation of O2 and NO2 species. Field ion and field emission electron microscopies (FIM and FEM) were used to characterise the apex of tip samples before, during and after the catalytic reactions. On rhodium samples, the exposure of less than 10 Langmuir of O2 is sufficient to induce significant morphological changes. At higher exposures, the presence of subsurface oxygen causes surface reconstructions illustrated with atomic resolution by FIM at 50 K. The same pattern is also visible at 505 K in the presence of H2 and O2 during water production. Upon the decrease of H2 pressure, surface oxidation shows a strong sensitivity to the local surface initiated along the zone lines. On platinum, the kinetic instabilities of the NO2-H2 reaction are followed by FEM at 390 K starting from a hemispherical tip sample. The instabilities are expressed as surface explosions occurring randomly in time, but synchronised over {0 1 1} facets. These instabilities expand along the lines over the (0 0 1) pole and exhibit self-sustained kinetic oscillations. The analysis of the tips by FIM after the reaction shows dark regions over the {1 1 3} facets, suggesting the extension of those to the detriment of vicinal ones. A well-controlled field evaporation procedure reveals that these regions appear dark due to the presence of surface oxygen. Structural reconstructions are observed but do not lead to the drastic morphological changes suggested by the FIM and FEM patterns. Nanoparticle dynamics must be accounted in models describing the non-linear features of catalytic reactions and more generally included in the description of catalytic properties of nanosized particles.

  13. Oxygen assisted reconstructions of rhodium and platinum nanocrystals and their effects on local catalytic activity of hydrogenation reactions

    Energy Technology Data Exchange (ETDEWEB)

    Barroo, C.; Gilis, N.; Lambeets, S.V.; Devred, F.; Visart de Bocarmé, T., E-mail: tvisart@ulb.ac.be

    2014-06-01

    The reconstruction of rhodium and platinum crystals of some tens of nanometres diameter was investigated during the ongoing hydrogenation of oxygen atoms resulting from the dissociation of O{sub 2} and NO{sub 2} species. Field ion and field emission electron microscopies (FIM and FEM) were used to characterise the apex of tip samples before, during and after the catalytic reactions. On rhodium samples, the exposure of less than 10 Langmuir of O{sub 2} is sufficient to induce significant morphological changes. At higher exposures, the presence of subsurface oxygen causes surface reconstructions illustrated with atomic resolution by FIM at 50 K. The same pattern is also visible at 505 K in the presence of H{sub 2} and O{sub 2} during water production. Upon the decrease of H{sub 2} pressure, surface oxidation shows a strong sensitivity to the local surface initiated along the 〈0 0 1〉 zone lines. On platinum, the kinetic instabilities of the NO{sub 2}–H{sub 2} reaction are followed by FEM at 390 K starting from a hemispherical tip sample. The instabilities are expressed as surface explosions occurring randomly in time, but synchronised over {0 1 1} facets. These instabilities expand along the 〈0 0 1〉 lines over the (0 0 1) pole and exhibit self-sustained kinetic oscillations. The analysis of the tips by FIM after the reaction shows dark regions over the {1 1 3} facets, suggesting the extension of those to the detriment of vicinal ones. A well-controlled field evaporation procedure reveals that these regions appear dark due to the presence of surface oxygen. Structural reconstructions are observed but do not lead to the drastic morphological changes suggested by the FIM and FEM patterns. Nanoparticle dynamics must be accounted in models describing the non-linear features of catalytic reactions and more generally included in the description of catalytic properties of nanosized particles.

  14. Conceptual design of 1 GW class hybrid energy transfer line of hydrogen and electricity

    International Nuclear Information System (INIS)

    Applicability of 1 GW class hybrid energy transfer line of hydrogen and electricity is investigated in this report. Hydrogen refrigeration station is placed on every 10 km of the unit section. The rated current is 10 kA, and operation voltage is 100 kV (+ 50 kV and -50 kV for ground). Delivery capacity of the liquid hydrogen is 100 tons per day. The HETL consists of the SC cable, electrical insulation layer, channel for liquid hydrogen, inner corrugated tube, vacuum space for thermal insulation and outer corrugated tube. The special multi-filamentary MgB2 wire was developed to improve the Ic performance against bending strain. When the pressure of liquid hydrogen increases, boiling temperature of liquid hydrogen becomes high. Pressurization of liquid hydrogen enables to expand operation temperature region of the MgB2 cable, and to absorb the head loss of the installation route. To obtain the operation temperature from 20 K to 25 K, pressure of liquid hydrogen from 0.4 to 0.6 MPa was chosen. When the heat leak into the liquid hydrogen is 1.0 W/m (expected value), the temperature at the outlet becomes 21.8 K. It was confirmed that this HETL is one of the attractive energy transportation system which combines hydrogen fuel and SC power transmission.

  15. High performing and stable supported nano-alloys for the catalytic hydrogenation of levulinic acid to γ-valerolactone

    Science.gov (United States)

    Luo, Wenhao; Sankar, Meenakshisundaram; Beale, Andrew M.; He, Qian; Kiely, Christopher J.; Bruijnincx, Pieter C. A.; Weckhuysen, Bert M.

    2015-03-01

    The catalytic hydrogenation of levulinic acid, a key platform molecule in many biorefinery schemes, into γ-valerolactone is considered as one of the pivotal reactions to convert lignocellulose-based biomass into renewable fuels and chemicals. Here we report on the development of highly active, selective and stable supported metal catalysts for this reaction and on the beneficial effects of metal nano-alloying. Bimetallic random alloys of gold-palladium and ruthenium-palladium supported on titanium dioxide are prepared with a modified metal impregnation method. Gold-palladium/titanium dioxide shows a marked,~27-fold increase in activity (that is, turnover frequency of 0.1 s-1) compared with its monometallic counterparts. Although ruthenium-palladium/titanium dioxide is not only exceptionally active (that is, turnover frequency of 0.6 s-1), it shows excellent, sustained selectivity to γ-valerolactone (99%). The dilution and isolation of ruthenium by palladium is thought to be responsible for this superior catalytic performance. Alloying, furthermore, greatly improves the stability of both supported nano-alloy catalysts.

  16. Process concept for hydrogen production by catalytic conversion of defined kerosene fractions; Verfahrenskonzept zur Wasserstofferzeugung durch katalytische Umwandlung definierter Kerosinfraktionen

    Energy Technology Data Exchange (ETDEWEB)

    Frick, Viktoria

    2011-06-15

    The innovative process concept presented in this thesis for on-board hydrogen generation from kerosene for power generation aboard aircrafts by fuel cell systems exhibits significant advantages on reaction and process level compared to the hydrogen production via reforming. It includes the separation of a defined low-sulphur fraction from kerosene via rectification or crystallization which is subsequently converted catalytically to hydrogen. To investigate thermal management and process integration of the overall system four possible process concepts have been identified and their overall efficiency has been compared to a reference concept by process simulation. The key process parameters for fractionation were derived from experimental investigations. The processes with dehydrogenation resulted in the highest hydrogen yield and an overall electrical efficiency of 43 % could be achieved in combination with crystallization, which is a significant increase against the reference concept. Taking aircraft specific boundary conditions into account this process concept has been derived as the lead concept. Moreover, it avoids the unsolved until now problems connected to undesirable production of NO{sub x} and CO. [German] Das im Rahmen dieser Arbeit erarbeitete innovative Prozesskonzept zur on-board Wasserstofferzeugung aus Kerosin fuer den Betrieb von Brennstoffzellensystemen zur Energieversorgung im Flugzeug weist erhebliche reaktions- und verfahrenstechnische Vorteile gegenueber der Wasserstofferzeugung mittels Reformierung auf. Es beinhaltet die Abtrennung, einer definierten schwefelarmen Fraktion des Kerosins mittels Rektifikation oder Kristallisation. Diese wird in einem nachfolgenden Schritt katalytisch zu Wasserstoff umgewandelt. Zur Untersuchung der Waermeintegration und Prozessfuehrung im Gesamtsystem wurden vier moegliche Verfahrenskonzepte identifiziert und deren Systemwirkungsgrade mittels Prozesssimulation mit einem Referenzkonzept verglichen. Die

  17. Catalytic hydrogen production from fossil fuels via the water gas shift reaction

    International Nuclear Information System (INIS)

    Highlights: • Hydrogen is a clean alternative to hydrocarbon fuels. • Hydrogen is primarily produced with the water gas shift reaction. • Development of water gas shift catalysts is essential to the energy industry. • This work summarizes recent progress in water gas shift catalyst research. - Abstract: The production of hydrogen is a highly researched topic for many reasons. First of all, it is a clean fuel that can be used instead of hydrocarbons, which produce CO2, a greenhouse gas emission that is thought to be the reason for climate change in the world. The largest source of hydrogen is the water gas shift (WGS) reaction, where CO and water are mixed over a catalyst to produce the desired hydrogen. Many researchers have focused on development of WGS catalysts with different metals. The most notable of these metals are precious and rare earth metals which, when combined, have unique properties for the WGS reaction. Research in this area is very important to the energy industry and the future of energy around the world. However, the progress made recently has not been reviewed, and this review was designed to fill the gap

  18. High Catalytic Activity and Chemoselectivity of Sub-nanometric Pd Clusters on Porous Nanorods of CeO2 for Hydrogenation of Nitroarenes.

    Science.gov (United States)

    Zhang, Sai; Chang, Chun-Ran; Huang, Zheng-Qing; Li, Jing; Wu, Zhemin; Ma, Yuanyuan; Zhang, Zhiyun; Wang, Yong; Qu, Yongquan

    2016-03-01

    Sub-nanometric Pd clusters on porous nanorods of CeO2 (PN-CeO2) with a high Pd dispersion of 73.6% exhibit the highest catalytic activity and best chemoselectivity for hydrogenation of nitroarenes to date. For hydrogenation of 4-nitrophenol, the catalysts yield a TOF of ∼44059 h(-1) and a chemoselectivity to 4-aminophenol of >99.9%. The superior catalytic performance can be attributed to a cooperative effect between the highly dispersed sub-nanometric Pd clusters for hydrogen activation and unique surface sites of PN-CeO2 with a high concentration of oxygen vacancy for an energetically and geometrically preferential adsorption of nitroarenes via nitro group. The high concentration of surface defects of PN-CeO2 and large Pd dispersion contribute to the enhanced catalytic activity for the hydrogenation reactions. The high chemoselectivity is mainly governed by the high Pd dispersion on the support. The catalysts also deliver high catalytic activity and selectivity for nitroaromatics with various reducible substituents into the corresponding aminoarenes. PMID:26828123

  19. Facile synthesis of polypyrrole functionalized nickel foam with catalytic activity comparable to Pt for the poly-generation of hydrogen and electricity

    Science.gov (United States)

    Tang, Tiantian; Li, Kan; Shen, Zhemin; Sun, Tonghua; Wang, Yalin; Jia, Jinping

    2016-01-01

    Polypyrrole functionalized nickel foam is facilely prepared through the potentiostatic electrodeposition. The PPy-functionalized Ni foam functions as a hydrogen-evolution cathode in a rotating disk photocatalytic fuel cell, in which hydrogen energy and electric power are generated by consuming organic wastes. The PPy-functionalized Ni foam cathode exhibits stable catalytic activities after thirteen continuous runs. Compared with net or plate structure, the Ni foam with a unique three-dimensional reticulate structure is conducive to the electrodeposition of PPy. Compared with Pt-group electrode, PPy-coated Ni foam shows a satisfactory catalytic performance for the H2 evolution. The combination of PPy and Ni forms a synergistic effect for the rapid trapping and removal of proton from solution and the catalytic reduction of proton to hydrogen. The PPy-functionalized Ni foam could be applied in photocatalytic and photoelectrochemical generation of H2. In all, we report a low cost, high efficient and earth abundant PPy-functionalized Ni foam with a satisfactory catalytic activities comparable to Pt for the practical application of poly-generation of hydrogen and electricity.

  20. Molybdatophosphoric acid as an efficient catalyst for the catalytic and chemoselective oxidation of sulfides to sulfoxides using urea hydrogen peroxide as a commercially available oxidant

    Directory of Open Access Journals (Sweden)

    ALIREZA HASANINEJAD

    2010-03-01

    Full Text Available An efficient procedure for the chemoselective oxidation of alkyl (aryl sulfides to the corresponding sulfoxides using urea hydrogen peroxide (UHP in the presence of a catalytic amount of molybdatophosphoric acid at room temperature is described. The advantages of described method are: generality, high yield and chemoselectivity, short reaction time, low cost and compliment with green chemistry protocols.

  1. Selective Catalytic Hydrogenations of Nitriles, Ketones, and Aldehydes by Well-Defined Manganese Pincer Complexes.

    Science.gov (United States)

    Elangovan, Saravanakumar; Topf, Christoph; Fischer, Steffen; Jiao, Haijun; Spannenberg, Anke; Baumann, Wolfgang; Ludwig, Ralf; Junge, Kathrin; Beller, Matthias

    2016-07-20

    Hydrogenations constitute fundamental processes in organic chemistry and allow for atom-efficient and clean functional group transformations. In fact, the selective reduction of nitriles, ketones, and aldehydes with molecular hydrogen permits access to a green synthesis of valuable amines and alcohols. Despite more than a century of developments in homogeneous and heterogeneous catalysis, efforts toward the creation of new useful and broadly applicable catalyst systems are ongoing. Recently, Earth-abundant metals have attracted significant interest in this area. In the present study, we describe for the first time specific molecular-defined manganese complexes that allow for the hydrogenation of various polar functional groups. Under optimal conditions, we achieve good functional group tolerance, and industrially important substrates, e.g., for the flavor and fragrance industry, are selectively reduced. PMID:27219853

  2. 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...

  3. Synthesis and Catalytic Performance of Graphene Modified CuO-ZnO- for Hydrogenation to Methanol

    OpenAIRE

    Zheng-juan Liu; Xing-jiang Tang; Shan Xu; Xiao-lai Wang

    2014-01-01

    CuO-ZnO-Al2O3 and graphene nanosheet (GNS) were synthesized by coprecipitation route and reduction of exfoliated graphite oxides method, respectively. GNS modified CuO-ZnO-Al2O3 nanocomposites were synthesized by high energy ball milling method. The structure, morphology, and character of the synthesized materials were studied by BET, XRD, TEM, and H2-TPR. It was found that by high energy ball milling method the CuO-ZnO-Al2O3 nanoparticles were uniformly dispersed on GNS surfaces. The catalyt...

  4. Relating catalytic activity and electrochemical properties: The case of arene-ruthenium phenanthroline complexes catalytically active in transfer hydrogenation

    Czech Academy of Sciences Publication Activity Database

    Štěpnička, P.; Ludvík, Jiří; Canivet, J.; Süss-Fink, G.

    2006-01-01

    Roč. 359, č. 8 (2006), s. 2369-2374. ISSN 0020-1693 R&D Projects: GA AV ČR IAA4040304 Institutional research plan: CEZ:AV0Z40400503 Keywords : arene complexes * chloro complexes * aqua complexes Subject RIV: CG - Electrochemistry Impact factor: 1.674, year: 2006

  5. Numerical study of the behavior of methane-hydrogen/air pre-mixed flame in a micro reactor equipped with catalytic segmented bluff body

    International Nuclear Information System (INIS)

    In this work, combustion characteristics of premixed methane-hydrogen/air in a micro reactor equipped with a catalytic bluff body is investigated numerically. In this regard, the detailed chemistry schemes for gas phase (homogeneous) and the catalyst surface (heterogeneous) are used. The applied catalytic bluff body is coated with a thin layer of platinum (Pt) on its surface. Also, the lean reactive mixture is entered to the reactor with equivalence ratio 0.9. The results of this study showed that the use of catalytic bluff body in the center of a micro reactor can significantly increase the flame stability, especially at high velocities. Moreover, it is found that a catalytic bluff body with several cavities on its surface and also high thermal conductivity improves the flame stability more than a catalytic bluff body without cavities and low thermal conductivity. Finally, it is maintained that the most advantage of using the catalytic bluff body is its easy manufacturing process as compared to the catalytic wall. This matter seems to be more prevalent when we want to create several cavities with various sizes on the bluff-body. - Highlights: • Presence of a bluff body in a micro reactor can move the flame towards the upstream. • Catalytic bluff body can significantly increase flame stability at high velocities. • Creating non-catalytic cavities on the bluff body promotes homogeneous reactions. • Segmented catalytic bluff body improves the flame stability more than a simple one. • Creating the segments on a bluff body is easier compared to a wall

  6. Mass and heat transfer on B7 structured packing in separation of hydrogen isotopes by distillation

    International Nuclear Information System (INIS)

    The paper contains theoretical and experimental data about mass and heat transfer on B7 type structured packing in deuterium separation processes by distillation. A mathematical model for simultaneous description of transfer processes, prediction of distillation column function, operated at total reflux, details about experimental plants, operation conditions and experimental data regarding mass and heat transfer in vacuum distillation of water and in cryogenic distillation of hydrogen are presented. Efficiency of isotopic separation on B7 structured packing is presented, in both cases, according to a dynamic model, by height of transfer unit (HTU). (authors)

  7. New Ruthenium Complexes Based on Tetradentate Bipyridine Ligands for Catalytic Hydrogenation of Esters.

    Science.gov (United States)

    Wang, Fangyuan; Tan, Xuefeng; Lv, Hui; Zhang, Xumu

    2016-08-01

    New bipyridinemethanamine-containing tetradentate ligands and their corresponding ruthenium complexes have been synthesized. The synthesized complexes performed well in the hydrogenation of a variety of esters with high efficiency (TON up to 9700) giving alcohols in good yields. PMID:27385062

  8. Catalytic Ionic Hydrogenation of Ketones by {[Cp*Ru(CO)2]2(µ-H)}+

    Energy Technology Data Exchange (ETDEWEB)

    Bullock, R.M.; Fagan, P.J.; Voges, M.H.

    2010-02-22

    {l_brace}[Cp*Ru(CO){sub 2}]{sub 2}({mu}-H){r_brace}{sup +}OTf{sup -} functions as a homogeneous catalyst precursor for hydrogenation of ketones to alcohols, with hydrogenations at 1 mol % catalyst loading at 90 C under H{sub 2} (820 psi) proceeding to completion and providing >90% yields. Hydrogenation of methyl levulinate generates {gamma}-valerolactone, presumably by ring-closing of the initially formed alcohol with the methyl ester. Experiments in neat Et{sub 2}C=O show that the catalyst loading can be <0.1 mol % and that at least 1200 turnovers of the catalyst can be obtained. These reactions are proposed to proceed by an ionic hydrogenation pathway, with the highly acidic dihydrogen complex [Cp*Ru(CO){sub 2}({eta}{sup 2}-H{sub 2})]{sup +}OTf{sup -} being formed under the reaction conditions from reaction of H2 with {l_brace}[Cp*Ru(CO){sub 2}]{sub 2}({mu}-H){r_brace}{sup +}OTf{sup -}.

  9. Catalytic conversion of biomass-derived feedstocks into olefins and aromatics with ZSM-5: the hydrogen to carbon effective ratio

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Huiyan; Cheng, Yu-Ting; Vispute, Tushar; Xiao, R; Huber, George W.

    2011-01-01

    Catalytic conversion of ten biomass-derived feedstocks, i.e.glucose, sorbitol, glycerol, tetrahydrofuran, methanol and different hydrogenated bio-oil fractions, with different hydrogen to carbon effective (H/C{sub eff}) ratios was conducted in a gas-phase flow fixed-bed reactor with a ZSM-5 catalyst. The aromatic + olefin yield increases and the coke yield decreases with increasing H/C{sub eff} ratio of the feed. There is an inflection point at a H/C{sub eff} ratio = 1.2, where the aromatic + olefin yield does not increase as rapidly as it does prior to this point. The ratio of olefins to aromatics also increases with increasing H/C{sub eff} ratio. CO and CO₂ yields go through a maximum with increasing H/C{sub eff} ratio. The deactivation rate of the catalyst decreases significantly with increasing H/C{sub eff} ratio. Coke was formed from both homogeneous and heterogeneous reactions. Thermogravimetric analysis (TGA) for the ten feedstocks showed that the formation of coke from homogeneous reactions decreases with increasing H/C{sub eff} ratio. Feedstocks with a H/C{sub eff} ratio less than 0.15 produce large amounts of undesired coke (more than 12 wt%) from homogeneous decomposition reactions. This paper shows that the conversion of biomass-derived feedstocks into aromatics and olefins using zeolite catalysts can be explained by the H/C{sub eff} ratio of the feed.

  10. Experimental studies on catalytic hydrogen recombiners for light water reactors; Experimentelle Untersuchungen zu katalytischen Wasserstoffkombinatoren fuer Leichtwasserreaktoren

    Energy Technology Data Exchange (ETDEWEB)

    Drinovac, P.

    2006-06-19

    In the course of core melt accidents in nuclear power plants a large amount of hydrogen can be produced and form an explosive or even detonative gas mixture with aerial oxygen in the reactor building. In the containment atmosphere of pressurized water reactors hydrogen combines a phlogistically with the oxygen present to form water vapor even at room temperature. In the past, experimental work conducted at various facilities has contributed little or nothing to an understanding of the operating principles of catalytic recombiners. Hence, the purpose of the present study was to conduct detailed investigations on a section of a recombiner essentially in order to deepen the understanding of reaction kinetics and heat transport processes. The results of the experiments presented in this dissertation form a large data base of measurements which provides an insight into the processes taking place in recombiners. The reaction-kinetic interpretation of the measured data confirms and deepens the diffusion theory - proposed in an earlier study. Thus it is now possible to validate detailed numeric models representing the processes in recombiners. Consequently the present study serves to broaden and corroborate competence in this significant area of reactor technology. In addition, the empirical knowledge thus gained may be used for a critical reassessment of previous numeric model calculations. (orig.)

  11. Sub-10 nm Platinum Nanocrystals with Size and Shape Control: Catalytic Study for Ethylene and Pyrrole Hydrogenation

    Energy Technology Data Exchange (ETDEWEB)

    Tsung, Chia-Kuang; Kuhn, John N.; Huang, Wenyu; Aliaga, Cesar; Hung, Ling-I; Somorjai, Gabor A.; Yang, Peidong

    2009-03-02

    Platinum nanocubes and nanopolyhedra with tunable size from 5 to 9 nm were synthesized by controlling the reducing rate of metal precursor ions in a one-pot polyol synthesis. A two-stage process is proposed for the simultaneous control of size and shape. In the first stage, the oxidation state of the metal ion precursors determined the nucleation rate and consequently the number of nuclei. The reaction temperature controlled the shape in the second stage by regulation of the growth kinetics. These well-defined nanocrystals were loaded into MCF-17 mesoporous silica for examination of catalytic properties. Pt loadings and dispersions of the supported catalysts were determined by elemental analysis (ICP-MS) and H2 chemisorption isotherms, respectively. Ethylene hydrogenation rates over the Pt nanocrystals were independent of both size and shape and comparable to Pt single crystals. For pyrrole hydrogenation, the nanocubes enhanced ring-opening ability and thus showed a higher selectivity to n-butylamine as compared to nanopolyhedra.

  12. Determination of height of transfer unit at hydrogen isotopic distillation on B7 type structured packing

    International Nuclear Information System (INIS)

    Due to the low pressure drop which that the structured packing introduces it is often used in the case of distillations under vacuum and of the mixture separation when the desired component is present in very low concentration, for example the water, hydrogen and oxygen isotopic distillation. The paper presents a model for the determination of height of transfer unit at hydrogen isotopic distillation plant with structured B7 type packing. The values of HTU calculated with the analogy model between the heat, momentum and mass transfer are compared with the experimental data. (authors)

  13. Height of transfer unit determination at hydrogen isotopic distillation on B7 type structured packing

    International Nuclear Information System (INIS)

    Due to the low pressure drop that it introduces, the structured packing is often used in the case of distillation under vacuum and of the mixture separation when the desired component is found in very low concentration, for example the water, hydrogen and oxygen isotopic distillation. The paper presents a model for the determination of height of transfer unit at hydrogen isotopic distillation plant with structured B7 type packing. The values of HTU calculated with the analogy model between the heat, momentum and mass transfer are compared with the experimental data. (authors)

  14. Height of transfer unit determination at hydrogen isotopic distillation on B7 - type ordered packing

    International Nuclear Information System (INIS)

    The ordered packing, due to the low pressure drop that it introduces, is often used in the case of distillations under vacuum and of the mixture separation when the valuable component is found in very low concentration, as for instance, in the case of water, hydrogen and oxygen isotopic distillation. The paper presents a model for height of transfer unit determination at hydrogen isotopic distillation on B7 - type ordered packing. The values of HTU, calculated with the model based on the analogy between the heat, momentum and mass transfer are compared with the experimentally determined values. (authors)

  15. An Updated Synthesis of the Diazo-Transfer Reagent Imidazole-1-sulfonyl Azide Hydrogen Sulfate.

    Science.gov (United States)

    Potter, Garrett T; Jayson, Gordon C; Miller, Gavin J; Gardiner, John M

    2016-04-15

    Imidazole-1-sulfonyl azide and salts thereof are valuable reagents for diazo-transfer reactions, most particularly conversion of primary amines to azides. The parent reagent and its HCl salt present stability and detonation risks, but the hydrogen sulfate salt is significantly more stable. An updated procedure for the large-scale synthesis of this salt avoids isolation or concentration of the parent compound or HCl salt and will facilitate the use of hydrogen sulfate salt as the reagent of choice for diazo transfer. PMID:26998999

  16. A diabatic state model for double proton transfer in hydrogen bonded complexes

    CERN Document Server

    McKenzie, Ross H

    2014-01-01

    Four diabatic states are used to construct a simple model for double proton transfer in hydrogen bonded complexes. Key parameters in the model are the proton donor-acceptor separation R and the ratio, D_1/D_2, between the proton affinity of a donor with one and two protons. Depending on the values of these two parameters the model describes four qualitatively different ground state potential energy surfaces, having zero, one, two, or four saddle points. In the limit D_2=D_1 the model reduces to two decoupled hydrogen bonds. As R decreases a transition can occur from a concerted to a sequential mechanism for double proton transfer.

  17. An S-N2-model for proton transfer in hydrogen-bonded systems

    DEFF Research Database (Denmark)

    Kuznetsov, A.M.; Ulstrup, Jens

    2004-01-01

    A new mechanism of proton transfer in donor-acceptor complexes with long hydrogen bonds is suggested. The transition is regarded as totally adiabatic. Two closest water molecules that move synchronously by hindered translation to and from the reaction complex are crucial. The water molecules induce...... a shift of the proton from the donor to the acceptor with simultaneous breaking/formation of hydrogen bonds between these molecules and the proton donor and acceptor. Expressions for the activation barrier and kinetic hydrogen isotope effect are derived. The general scheme is illustrated with the...

  18. Spatially selective materials deposition by hydrogen-assisted laser-induced transfer

    International Nuclear Information System (INIS)

    Si and Al lines were deposited on glass substrates using a transfer technique based on the explosive release of hydrogen from a hydrogenated amorphous Si film melted by a laser pulse. The Si lines have a minimum width of 4.5 μm and are well defined, while the Al lines are wider and less uniform. Analysis of time-resolved infrared transmission signals reveals that the lines do not break into droplets upon ejection, in contrast to the behavior of unpatterned films. This difference is attributed to the escape of hydrogen through the sides of the molten lines into the adjacent material. (c) 2000 American Institute of Physics

  19. Mass and heat transfer on B7 ordered packing in hydrogen isotope separation by distillation

    International Nuclear Information System (INIS)

    This work presents theoretical and experimental data referring to mass and heat transfer on B7 ordered packing in deuterium isotope separation by distillation. The first part is devoted to the study of mass transfer in hydrogen isotopic distillation while the second one treats the mass and heat transfer in water isotopic distillation. A stationary mathematical model for the mass and heat transfer was developed based on multitubular column model with wet wall. This model allowed the calculation starting from theoretical data of the ordered packing efficiency, expressed by the transfer unit height, TUH. Also, from theoretical data the mass and heat transfer coefficients were determined. A test of the mathematical model was performed with the experimental data obtained from two laboratory installations for hydrogen isotope separation by distillation. From the first installation, experimental data concerning the B7 ordered packing efficiency were obtained for the deuterium separation by cryogenic distillation at the - 250 deg C level. With the second one data referring to the mass and heat transfer on the same packing were obtained for the deuterium separation by water distillation under vacuum at the 60 deg C level. The values of TUH, mass and heat transfer coefficients as theoretically evaluate and experimentally checked are in agreement with the respective values obtained in separation processes in chemical industry. This is the fact which endorses utilization of the model of multitubular column with wet wall for describing the transfer processes in distillation columns equipped with B7 ordered packing

  20. Mass transfer of corrosion products and corrosion of steel in sodium at high hydrogen concentrations

    Science.gov (United States)

    Alekseev, V. V.; Kozlov, F. A.; Sorokin, A. P.; Varseev, E. V.; Orlova, E. A.; Torbenkova, I. Yu.

    2015-10-01

    Serviceability of steels in a loop having an increased content of hydrogen is estimated. The equilibrium pressure of hydrogen in a sodium loop saturated with hydrogen is around 10 MPa at a temperature of approximately 630°C and around 100 MPa at 800°C. At the hydrogen pressure equal to 10 MPa, steel with a chromium content of 5% is serviceable to a temperature of 840°C, and steel with a chromium content of 25% is serviceable in the entire considered range of temperatures (above 600°C). At a hydrogen pressure of 80 MPa, steel containing 5% of chromium is not serviceable in the entire considered range of temperatures, and steel containing 25% of chromium is serviceable to a temperature of 830°C. The article presents the results from experimental investigations of the effect of hydrogen on corrosion and mass transfer of corrosion products in a sodium loop at the hydrogen concentration in sodium equal to 6 ppm, which were carried out in the high-temperature section of the sodium test facility (the test facility and the investigation methodology were described in the previous publications of the authors). The distributions of chromium and nickel flows toward the walls over the channel length are obtained at increased hydrogen content (around 6 ppm) and at low oxygen content (less than 2 ppm) in sodium and at a temperature of up to 780°C. For the conditions with relatively low content of oxygen and hydrogen in sodium, the experimental values of chromium flow toward the channel wall are consistent with the calculated data. This fact confirms the possibility of using the previously obtained physicochemical constants for calculating the mass transfer of chromium in high-temperature sodium loops at an increased content of hydrogen in sodium.

  1. Mass and heat transfer on B7 structured packing in hydrogen isotope separation by distillation

    International Nuclear Information System (INIS)

    Due to the low pressure drop required by structured packing it is often used in the case of distillations under vacuum and of mixture separation when the valuable component is founded in very low concentration, as for instance in case of water, hydrogen and oxygen isotopic distillation. The paper contains theoretical and experimental data about mass and heat transfer on B7 type structured packing, in deuterium separation processes by distillation. It is presented a mathematical model for simultaneous description of transfer processes and prediction of functioning of a distillation column, operated at total reflux, as well as details about experimental plants, operation conditions and experimental data regarding mass and heat transfer in vacuum distillation of water and in hydrogen cryogenic distillation. Efficiency of isotopic separation on B7 structured packing is presented, in both cases, by means of a dynamical model depending on the height of transfer unit (HTU). (authors)

  2. COx Free Hydrogen Production by Catalytic Decomposition of Methane Over Porous Ni/Al2O3 Catalysts

    International Nuclear Information System (INIS)

    The prepared meso porous spherical alumina with high-surface area was employed as a support for nickel catalysts in methane decomposition reaction. It was observed that, the catalytic activity of Ni/Al2O3 catalysts was high at the initial times of reaction and decreased with time on stream, and finally reached a constant value. The deactivation rate of catalysts is dependent on the catalyst characteristics and the operating conditions. The activity results indicate that, the yield of hydrogen and the structure of deposited carbon are strongly dependent on the loading amount of Ni. The Scanning Electron Microscopy results showed that carbon formed on the catalysts in the form of filamentous carbon. Concerning hydrogen production, the 10% Ni/ Al2O3 catalyst leads to a higher yield, due to the higher amount of active phases which can catalyze further the number of methane molecules, while lesser amounts of filamentous carbon were observed on this catalyst than for 5 and 7.5% Ni/ Al2O3 catalysts at the same operating condition. The yield of hydrogen and structure of filamentous carbon also significantly depend on the reaction temperatures and residence time of gas in the reactor, as the 10% Ni/ Al2O3 catalyst showed a remarkable stability with a decrease of about 14% at 800degreeC and 25 ml/min after 240 min of reaction. The obtained results showed that the prepared Ni/ Al2O3 catalysts had a good activity in methane decomposition reaction, which is one of the highest activities among those for low nickel loaded catalysts reported up until now.

  3. Effect of Catalytic Cylinders on Autothermal Reforming of Methane for Hydrogen Production in a Microchamber Reactor

    OpenAIRE

    Yunfei Yan; Hongliang Guo; Li Zhang; Junchen Zhu; Zhongqing Yang; Qiang Tang; Xin Ji

    2014-01-01

    A new multicylinder microchamber reactor is designed on autothermal reforming of methane for hydrogen production, and its performance and thermal behavior, that is, based on the reaction mechanism, is numerically investigated by varying the cylinder radius, cylinder spacing, and cylinder layout. The results show that larger cylinder radius can promote reforming reaction; the mass fraction of methane decreased from 26% to 21% with cylinder radius from 0.25 mm to 0.75 mm; compact cylinder spaci...

  4. Biomedical and Forensic Applications of Combined Catalytic Hydrogenation-Stable Isotope Ratio Analysis

    Directory of Open Access Journals (Sweden)

    Mark A. Sephton

    2007-01-01

    Full Text Available Studies of biological molecules such as fatty acids and the steroid hormones have the potential to benefit enormously from stable carbon isotope ratio measurements of individual molecules. In their natural form, however, the body’s molecules interact too readily with laboratory equipment designed to separate them for accurate measurements to be made.Some methods overcome this problem by adding carbon to the target molecule, but this can irreversibly overprint the carbon source ‘signal’. Hydropyrolysis is a newly-applied catalytic technique that delicately strips molecules of their functional groups but retains their carbon skeletons and stereochemistries intact, allowing precise determination of the carbon source. By solving analytical problems, the new technique is increasing the ability of scientists to pinpoint molecular indicators of disease, elucidate metabolic pathways and recognise administered substances in forensic investigations.

  5. CFD simulation of hydrogen mixing and mitigation by means of passive auto-catalytic recombiners

    Energy Technology Data Exchange (ETDEWEB)

    Kelm, S.; Reinecke, E-A.; Jahn, W., E-mail: s.kelm@fz-juelich.de [Forschungszentrum Juelich GmbH, Juelich (Germany); Allelein, H-J. [RWTH Aachen Univ.. Aachen (Germany)

    2011-07-01

    Modeling of passive auto-catalytic recombiners (PARs) operation in containment geometries involves a large variety of scales; thus, a CFD calculation resolving all these scales would be much too expensive. Therefore, the mechanistic PAR model REKO-DIREKT, developed at Forschungszentrum Juelich, has been coupled with the commercial CFD code ANSYS CFX in order to simulate PAR operation as well as the induced flow and transport phenomena. Based on a short introduction of REKO-DIREKT, its interface to CFX and the explicit coupling scheme is discussed. The paper is finalized by a first demonstration of simulation capabilities on the basis of the ThAI PAR-4 experiment (Becker Technologies GmbH, Eschborn, Germany). (author)

  6. Mass transfer during catalytic reaction in electroosmotically driven flow in a channel microreactor

    Science.gov (United States)

    Sharma, Himanshu; Vasu, Nadapana; de, Sirshendu

    2011-05-01

    Analytical solution for concentration profile in a microreactor is obtained during heterogeneous catalytic reaction. Reaction occurs in rectangular microchannel with catalyst-coated walls. Flow is induced electroosmotically in the microchannel. A general solution is obtained for first order reaction using a power series solution. Profiles of conversion, cup-mixing concentration of reactant, etc. and variation of Sherwood number is analyzed as function of operating variables. Analytical solution is compared with numerical results.

  7. Theoretical investigation of the hydrogen atom transfer in the hydrated A–T base pair

    International Nuclear Information System (INIS)

    Highlights: ► We study the hydrated A–T base pair with 2 and 4 water molecules. ► We consider the dynamics of hydrogen transfer in the hydrogen bridges. ► We compare this study with experimental data and simple schemes. - Abstract: The hydrated A–T base pair has been studied in order to understand the structural modifications and their electronic rearrangements induced by the movement of the hydrogen atoms in the H-bonds. The comparison of these results with that of the nonhydrated system can explain the role of the H-bonds of the water molecules in this system. Two naïve schemes have been considered, one where the hydrogen bonds of the water molecules are only indirectly involved in the hydrogen atoms transfer between the bases and another where the water molecules are directly involved in this transfer. The results support the idea that the real mechanisms are more complexes than these schemes. Some new stable structures of the A–T(H2O)2 and the A–T(H2O)4 systems have been found and the mechanisms of their generations have been analysed.

  8. Ionisation of atomic hydrogen at intermediate momentum transfer

    International Nuclear Information System (INIS)

    Relative differential cross sections for the asymmetric coplanar (e,2e) reaction have been measured in three energy-sharing regions, for two of which the ionisation peak is about 1 a.u. off the Bethe ridge. Momentum transfer is intermediate between large (binary) and small (dipole) values, where the distorted-wave impulse and second Born approximations respectively give a good account of the experimental data. In addition to these approximations the distorted-wave Born approximation is calculated. It is somewhat superior to the distorted-wave impulse approximation and very much better than the second Born approximation

  9. Catalytic asymmetric synthesis of a tertiary benzylic carbon center via phenol-directed alkene hydrogenation.

    Science.gov (United States)

    Caille, Seb; Crockett, Rich; Ranganathan, Krishnakumar; Wang, Xiang; Woo, Jacqueline C S; Walker, Shawn D

    2011-07-01

    An expeditious synthetic approach to chiral phenol 1, a key building block in the preparation of a series of drug candidates, is reported. The strategy includes a cost-effective and readily scalable route to cyclopentanone 3 from isobutyronitrile (10). The sterically hindered and enolizable ketone 3 was subsequently employed in a challenging Grignard addition mediated by LaCl(3)·2LiCl. A novel preparation of the lanthanide reagent required for this transformation is described. To complete the process, a highly enantioselective hydrogenation step afforded the target (1). The importance of the phenol group to the success of this asymmetric transformation is discussed. PMID:21630712

  10. Loop reactor staged with structured fibrous catalytic layers for liquid-phase hydrogenations

    OpenAIRE

    Kiwi-Minsker, L.; Joannet, E.; Renken, A.

    2004-01-01

    A novel concept of a recycle loop reactor is developed with structured filamentous catalysts integrated as trays in a staged bubble column. The reactor can be operated in batch or continuous mode. Woven fabrics of activated carbon fibers (ACF) were used as support for the Pd catalyst. The loop reactor was tested in the 2-butyne-1,4-diol hydrogenation showing selectivity up to 97% towards 2-butene-1,4-diol at conversions up to 80%. The reactor behavior was described quant. assuming an ideally ...

  11. Magnetic Silica-Supported Ruthenium Nanoparticles: An Efficient Catalyst for Transfer Hydrogenation of Carbonyl Compounds

    Science.gov (United States)

    One-pot synthesis of ruthenium nanoparticles on magnetic silica is described which involve the in situ generation of magnetic silica (Fe3O4@ SiO2) and ruthenium nano particles immobilization; the hydration of nitriles and transfer hydrogenation of carbonyl compounds occurs in hi...

  12. An S-N2-model for proton transfer in hydrogen-bonded systems

    DEFF Research Database (Denmark)

    Kuznetsov, A.M.; Ulstrup, Jens

    2004-01-01

    A new mechanism of proton transfer in donor-acceptor complexes with long hydrogen bonds is suggested. The transition is regarded as totally adiabatic. Two closest water molecules that move synchronously by hindered translation to and from the reaction complex are crucial. The water molecules indu...

  13. Asymmetric transfer hydrogenation of 1-phenyl dihydroisoquinolines using Ru(II) diamine catalysts

    Czech Academy of Sciences Publication Activity Database

    Přech, J.; Václavík, J.; Šot, P.; Pecháček, J.; Vilhanová, B.; Januščák, J.; Syslová, K.; Pažout, R.; Maixner, J.; Zápal, Jakub; Kuzma, Marek; Kačer, P.

    2013-01-01

    Roč. 36, JUN 2013 (2013), s. 67-70. ISSN 1566-7367 R&D Projects: GA ČR GA104/09/1497; GA ČR GAP106/12/1276 Institutional support: RVO:61388971 Keywords : Asymmetric transfer hydrogen ation * N-alkylsulfonyl * Dihydroisoquinoline Subject RIV: CA - Inorganic Chemistry Impact factor: 3.320, year: 2013

  14. In Situ Monitoring of Asymmetric Transfer Hydrogenation of Imines Using NMR Spectrometry

    Czech Academy of Sciences Publication Activity Database

    Václavík, J.; Pecháček, J.; Přech, J.; Kuzma, Marek; Kačer, P.; Červený, L.

    2012-01-01

    Roč. 106, č. 3 (2012), s. 206-210. ISSN 0009-2770 R&D Projects: GA ČR GA104/09/1497 Institutional research plan: CEZ:AV0Z50200510 Keywords : NMR Spectrometry * asymmetric transfer hydrogenation Subject RIV: CE - Biochemistry Impact factor: 0.453, year: 2012

  15. Construction of the isocopalane skeleton: application of a desulfinylative 1,7-hydrogen atom transfer strategy.

    Science.gov (United States)

    Xiao, Xiong; Xu, ZhongYu; Zeng, Qian-Ding; Chen, Xi-Bo; Ji, Wen-Hao; Han, Ying; Wu, PeiYing; Ren, Jiangmeng; Zeng, Bu-Bing

    2015-06-01

    Two attractive chirons, aldehyde 6 and chloride 7, exhibiting functionalized ent-spongiane-type tricyclic skeletons (ABC ring system), have been constructed and their absolute configurations have been studied by NMR spectroscopy and confirmed by single-crystal X-ray diffraction. Both of these chirons are derived from commercially available andrographolide in good yield. Aldehyde 6 is obtained through a novel K2 S2 O8 -catalyzed aquatic ring-closing reaction of allylic sodium sulfonate and intramolecular 1,7-hydrogen atom transfer process. Further mechanistic investigations demonstrate that the 1,7-hydrogen atom transfer is a free-radical process, whereby hydrogen migrates from C18 to C17, as evidenced by double-18- deuterium-labeled isotope experiments. Prospective applications of these two chiral sources are also discussed. PMID:25907201

  16. Performance of biological hydrogen production process from synthesis gas, mass transfer in batch and continuous bioreactors

    International Nuclear Information System (INIS)

    Biological hydrogen production by anaerobic bacterium, rhodospirillum rubrum was studied in batch and continuous bioreactors using synthesis gas(Co) as substrate. The systems were operated at ambient temperature and pressure. Correlations available in the literature were used to estimate the gas-liquid mass transfer coefficients (KLa) in batch reactor. Based on experimental results for the continuous reactor, new correlation was generated. The results showed that the agitation. gas flow rate and dilution rate were greatly influenced the hydrogen production as well as on KLa. It was found that the KLa of continuous bioreactor was 180 times higher than the mass transfer coefficient reported in batch reactor. It can be considered that the estimation of KLa for the continuous bioreactor may be successful for the large-scale biological hydrogen production

  17. 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.

  18. CATALYTIC AND ELECTROCATALYTIC ACTIVITY OF Pt-Ru/C ELECTRODE FOR HYDROGEN OXIDATION IN ALKALINE

    Directory of Open Access Journals (Sweden)

    D. LABOU

    2008-07-01

    Full Text Available The kinetics of the oxidation of H2 on PtRu/C gas-diffusion electrode was studied by interfacing the electrode with aqueous electrolytes at different pH values. The conducting electrolytes were KOH and HClO4 aqueous solutions with different concentrations. It is shown that the nature of the aqueous electrolyte plays the role of an active catalyst support for the PtRu/C electrode which drastically affects its catalytic properties. During the aforementioned interaction, termed electrochemical metal support interaction (EMSI, the electrochemical potential of the electrons at the catalyst Fermi level is equalised with the electrochemical potential of the solvated electron in the aqueous electrolyte. The electrochemical experiments carried out at various pH values showed that the electrochemical promotion catalysis (EPOC is more intense when the catalyst-electrode is interfaced with electrolytes with high pH values where the OH– ionic conduction prevails. It was concluded that similar to the solid state electrochemical systems EPOC proceeds through the formation of a polar adsorbed promoting layer of , electrochemically supplied by the OH- species, at the three phase boundaries of the gas exposed gas diffusion catalyst-electrode surface.

  19. Bimetallic promotion of cooperative hydrogen transfer and heteroatom removal in coal liquefaction

    Energy Technology Data Exchange (ETDEWEB)

    Eisch, J.J.

    1992-04-07

    The ultimate objective of this research has been to uncover novel reagents and experimental conditions for heteroatom removal and hydrogen transfer processes, which would be applicable to the liquefaction of coal under low-severity conditions. To this end, one phase of this research has investigated the cleavage of carbon-heteroatom bonds involving sulfur, oxygen, nitrogen and halogen by subvalent transition-metal complexes. A second phase of the study has assessed the capability of the same transition-metal complexes or of organoaluminum Lewis acids to catalyze the cleavage of carbon-hydrogen bonds in aromatics and hence to promote hydrogen shuttling. Finally, a third phase of our work has uncovered a remarkable synergistic effect of combinations of transition metals with organoaluminum Lewis acids on hydrogen shuttling between aromatics and hydroaromatics. (VC)

  20. Hydrogen Production by Thermo-catalytic Decomposition of Natural Gas: Carbonaceous Catalysts

    International Nuclear Information System (INIS)

    TCD of CH4 using different kinds of carbon catalyst, activated carbons (AC) and carbon blacks (CB) have been studied. AC showed an acceptable initial reaction rate but they become rapidly deactivated, while CB with high surface area provided more stable and sustainable hydrogen production. Regeneration of the carbonaceous catalysts after deactivation, using CO2 as activating agent has been studied. A commercial active carbon has been selected for the regeneration tests. The optimum operation conditions for the catalysts regeneration have been studied, attending to the burn off of the catalysts during the regeneration, which is important for the self-consistence of the process, and the recovering in the surface area, which is one of the most important factors affecting the activity of these catalysts. (authors)

  1. General Tritium labelling of gentamicin C by catalytic hydrogen exchange reaction with tritiated water

    International Nuclear Information System (INIS)

    Gentamicin C was labelled with tritium by means of a PtO2 catalized hydrogen exchange reaction. Under the conditions of the exchange (100 mg of gentamicin, basic form, 0,3 ml H2O-3H, and 50 mg of prereduced PtO2) the radiochemical yield was 0,24, 0,38 and 0,48 % at 120oC, for 8, 16 and 24 hours respectively. Chemical yield for purified gentamicin was about 60 %. Purification was accoumplished with a cellulose column eluted with the lower phase of chloroform-methanol 17 % ammonium hydroxide (2:1:1, v/v). Chemical purity, determined by HPLC, was 96,5 % and radiochemical one was 95 % . Main exchange degradation products show biological activity. (Author). 12 refs

  2. General Tritium Labelling of Gentamicin C by catalytic hydrogen exchange Reaction with Tritiated Water

    International Nuclear Information System (INIS)

    Gentamicin C was labelled with tritium by means of a PtO2 catalyzed hydrogen exchange reaction. Under the conditions of the exchange (100 mg of gentamicin, basic form, 0,3 ml H2O-3H, and 50 mg of prereduced PtO2) the radiochemical yield was 0,24, 0,38 and 0,48 % at 120 degree celsius, for 8, 16 and 24 hours respectively. Chemical yield for purified gentamicin was about 60 %. Purification was accomplished with a cellulose column eluted with the lower phase of chloroform-methanol 17 % ammonium hydroxide (2:1:1, v/v) . Chemical purity, determined by HPLC, was 96,5 % and radiochemical one was 95. Main exchange degradation products show biological activity. (Author) 12 refs

  3. Catalytic Glycerol Hydrodeoxygenation under Inert Atmosphere: Ethanol as a Hydrogen Donor

    Directory of Open Access Journals (Sweden)

    Efterpi S. Vasiliadou

    2014-12-01

    Full Text Available Glycerol hydrodeoxygenation to 1,2-propanediol (1,2-PDO is a reaction of high interest. However, the need for hydrogen supply is a main drawback of the process. According to the concept investigated here, 1,2-propanediol is efficiently formed using bio-glycerol feedstock with H2 formed in situ via ethanol aqueous phase reforming. Ethanol is thought to be a promising H2 source, as it is alcohol that can be used instead of methanol for transesterification of oils and fats. The H2 generated is consumed in the tandem reaction of glycerol hydrodeoxygenation. The reaction cycle proceeds in liquid phase at 220–250 °C and 1.5–3.5 MPa initial N2 pressure for a 2 and 4-h reaction time. Pt-, Ni- and Cu-based catalysts have been synthesized, characterized and evaluated in the reaction. Among the materials tested, Pt/Fe2O3-Al2O3 exhibited the most promising performance in terms of 1,2-propanediol productivity, while reusability tests showed a stable behavior. Structural integrity and no formation of carbonaceous deposits were verified via Temperature Programmed Desorption of hydrogen (TPD-H2 and thermogravimetric analysis of the fresh and used Pt/FeAl catalyst. A study on the effect of various operating conditions (reaction time, temperature and pressure indicated that in order to maximize 1,2-propanediol productivity and yield, milder reaction conditions should be applied. The highest 1,2-propanediol yield, 53% (1.1 g1,2-PDO gcat−1·h−1, was achieved at a lower reaction temperature of 220 °C.

  4. Experimental and numerical investigations of a hydrogen-assisted laser-induced materials transfer procedure

    International Nuclear Information System (INIS)

    We present investigations of the mechanisms of a laser-induced transfer technique, which can be used for the spatially selective deposition of materials such as Si. This transfer is effected by irradiating the backside of a hydrogenated amorphous silicon film, deposited on a transparent substrate with an excimer laser pulse. The resulting release and accumulation of hydrogen at the film/substrate interface propels the silicon onto an adjacent receptor wafer. Time-resolved infrared transmission measurements indicate that the amorphous film is melted by the laser pulse and breaks into droplets during ejection. These droplets travel towards the receptor substrate and coalesce upon arrival. The transfer velocity increases as a function of fluence, the rate of increase dropping noticeably around the full melt threshold of the film. At this fluence, the transfer velocity reaches values of around 1000 m/s for typical films. Atomic force microscopy reveals that films transferred below the full melt threshold only partially cover the receptor substrate, while uniform, well-adhering films, which can be smoothed by subsequent laser irradiation, are obtained above it. Transfer of hydrogen-free Si films, on the other hand, does not occur until much higher fluences. The dynamics of the process have been simulated using a semiquantitative numerical model. In this model, hydrogen released from the melt front is instantaneously accumulated at the interface with an initial kinetic energy given by the melting temperature of Si and the enthalpy of solution. The resulting pressure accelerates the Si film, the dynamics of which are modeled using Newtonian mechanics, and the gas cools adiabatically as its kinetic energy is converted to the film's momentum. The results of the calculations are in good agreement with the experimental data. (c) 2000 American Institute of Physics

  5. Catalytic cracking process

    Science.gov (United States)

    Lokhandwala, Kaaeid A.; Baker, Richard W.

    2001-01-01

    Processes and apparatus for providing improved catalytic cracking, specifically improved recovery of olefins, LPG or hydrogen from catalytic crackers. The improvement is achieved by passing part of the wet gas stream across membranes selective in favor of light hydrocarbons over hydrogen.

  6. Influence of rare-earth metal doping on the catalytic performance of CuO-CeO2 for the preferential oxidation of CO in excess hydrogen

    Institute of Scientific and Technical Information of China (English)

    Zhigang Liu; Renxian Zhou; Xiaoming Zheng

    2008-01-01

    Doping of different rare-earth metals(Pr,Nd,Y and La)had an evident influence on the catalytic performance of CuO-CeO2 for the preferential oxidation(PROX)Of CO in excess hydrogen.As for Pr,the doping enhanced the catalytic activity of CuO-CeO2 for PROX.For example,the CO conversion over the above catalyst for PROX was higher than 99%at 120℃.Especially.the doping of Pr widened the temperature window by 20℃ over CuO-CeO2 with 99%CO conversion.For Nd,Y and La,the doping depressed the catalytic activity of CuO-CeO2 for PROX.However,the doping of transition metals markedly improved the selectivity of CuO-CeO2 for PROX.

  7. Transfer of hydrogen and helium through corrugated, flexible tubes

    International Nuclear Information System (INIS)

    The transfer of liquid gas or cold gas through corrugated tubes is an alternative to rigid systems for the use in reactor technique. Advantages: flexibility for easy installation; these tubes together with their associated terminations and hardware are assembled, leak-tested and evacuated at the factory. This permits simple and cost saving installation on site. All tubes are helium leak-tested with a sensitivity of 10E-9 mbar 1/sec. Following the leak test, the vacuum space is pumped down to the operation vacuum level and properly sealed. The vacuum integrity is guaranteed as a result of the high degree of cleanliness observed during production and from the use of a specially selected better material inside the vacuum space. Disadvantage: pressure is limited to 20 bar. To fulfil all rules of the reactor safety, different tests have to be done. Because of the longitudinal weld of the corrugated tube, a bursting test of different sizes gives the best information of the liability of this kind of tube. It can be shown that the bursting pressure of such a tube is more than 5 times higher than the max. working pressure

  8. 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.

  9. Kinetic spectrophotometric determination of Bi(III based on its catalytic effect on the oxidation of phenylfluorone by hydrogen peroxide

    Directory of Open Access Journals (Sweden)

    SOFIJA M. RANČIĆ

    2009-08-01

    Full Text Available A new reaction was suggested and a new kinetic method was elaborated for determination of Bi(III in solution, based on its catalytic effect on the oxidation of phenyl-fluorone (PF by hydrogen peroxide in ammonia buffer. By application of spectrophotometric technique, a limit of quantification (LQ of 128 ng cm-3 was reached, and the limit of detection (LD of 37 ng cm-3 was obtained, where LQ was defined as the ratio signal:noise = 10:1 and LD was defined as signal 3:1 against the blank. The RSD value was found to be in the range 2.8–4.8 % for the investigated concentration range of Bi(III. The influence of some ions upon the reaction rate was tested. The method was confirmed by determining Bi(III in a stomach ulcer drug (“Bicit HP”, Hemofarm A.D.. The obtained results were compared to those obtained by AAS and good agreement of results was obtained.

  10. Phase- and morphology-controlled synthesis of cobalt sulfide nanocrystals and comparison of their catalytic activities for hydrogen evolution

    Science.gov (United States)

    Pan, Yuan; Liu, Yunqi; Liu, Chenguang

    2015-12-01

    Colalt sulfide nanocrystals (NCs), including dandelion-like Co9S8 and sphere-like Co3S4, have been synthesized via a thermal decomposition approach using cobalt acetylacetonate as the cobalt source, 1-dodecanethiol as the sulfur source and oleic acid or oleylamine as the high boiling organic solvent. It is found that the molar ratio of the Co:S precursor and the species of solvent play an important role in the control of phase and morphology of cobalt sulfide nanostructures. The phase structure and morphology of the as-synthesized nickel sulfide NCs are characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), scanning electron microscope (SEM), energy dispersive spectrum (EDS) mapping, X-ray photoelectron spectroscopy (XPS) and N2 adsorption-desorption. Then we further compare the electrocatalytic activity and stability of as-synthesized cobalt sulfide NCs for hydrogen evolution reaction (HER). The results show that sphere-like Co3S4 exhibits better electrocatalytic activity than the dandelion-like Co9S8 NCs for HER, which can be attributed to the difference of phase structure and morphology. The sphere-like Co3S4 NCs have large surface area and high electrical conductivity, both are beneficial to enhance the catalytic activity. This study indicates that the crystalline phase structure and morphology of cobalt sulfide NCs are important for designing HER electrocatalysts with high efficiency and good stability.

  11. Hydrogen-bonded Intramolecular Charge Transfer Excited State of Dimethylaminobenzophenone using Time Dependent Density Functional Theory

    Institute of Scientific and Technical Information of China (English)

    Yu-ling Chu; Zhong Yang; Zhe-feng Pan; Jing Liu; Yue-yi Han; Yong Ding; Peng Song

    2012-01-01

    Density functional theory and time-dependent density-functional theory have been used to investigate the photophysical properties and relaxation dynamics of dimethylaminobenzophenone (DMABP) and its hydrogen-bonded DMABP-MeOH dimer.It is found that,in nonpolar aprotic solvent,the transitions from S0 to S1 and S2 states of DMABP have both n→π* and π→π* characters,with the locally excited feature mainly located on the C=O group and the partial CT one characterized by electron transfer mainly from the dimethylaminophenyl group to the C=O group.But when the intermolecular hydrogen bond C=O…H-O is formed,the highly polar intramolecular charge transfer character switches over to the first excited state of DMABP-MeOH dimer and the energy difference between the two lowlying electronically excited states increases.To gain insight into the relaxation dynamics of DMABP and DMABP-MeOH dimer in the excited state,the potential energy curves for conformational relaxation are calculated.The formation of twisted intramolecular charge transfer state via diffusive twisting motion of the dimethylamino/dimethylaminophenyl groups is found to be the major relaxation process.In addition,the decay of the S1 state of DMABP-MeOH dimer to the ground state,through nonradiative intermolecular hydrogen bond stretching vibrations,is facilitated by the formation of the hydrogen bond between DMABP and alcohols.

  12. Photo-catalytic hydrogen production over Fe{sub 2}O{sub 3} based catalysts

    Energy Technology Data Exchange (ETDEWEB)

    Boudjemaa, A. [Technical and Scientific Research Centre of Physico-chemistry Analysis (CRAPC), BP 248, RP 16004, Algiers (Algeria); Laboratory of Chemistry of Natural Gas, Faculty of Chemistry (USTHB) BP 32, 16111 Algiers (Algeria); Trari, M. [Laboratory of Storage and Valorization of Renewable Energies, Faculty of Chemistry (USTHB) BP 32, 16111 Algiers (Algeria)

    2010-08-15

    The hydrogen photo-evolution was successfully achieved in aqueous (Fe{sub 1-x}Cr{sub x}){sub 2}O{sub 3} suspensions (0 {<=} x {<=} 1). The solid solution has been prepared by incipient wetness impregnation and characterized by X-ray diffraction, BET, transport properties and photo-electrochemistry. The oxides crystallize in the corundum structure, they exhibit n-type conductivity with activation energy of {proportional_to}0.1 eV and the conduction occurs via adiabatic polaron hops. The characterization of the band edges has been studied by the Mott Schottky plots. The onset potential of the photo-current is {proportional_to}0.2 V cathodic with respect to the flat band potential, implying a small existence of surface states within the gap region. The absorption of visible light promotes electrons into (Fe{sub 1-x}Cr{sub x}){sub 2}O{sub 3}-CB with a potential ({proportional_to}-0.5 V{sub SCE}) sufficient to reduce water into hydrogen. As expected, the quantum yield increases with decreasing the electro affinity through the substitution of iron by the more electropositive chromium which increases the band bending at the interface and favours the charge separation. The generated photo-voltage was sufficient to promote simultaneously H{sub 2}O reduction and SO{sub 3}{sup 2-} oxidation in the energetically downhill reaction (H{sub 2}O + SO{sub 3}{sup 2-} {yields} H{sub 2} + SO{sub 4}{sup 2-}, {delta}G = -17.68 kJ mol{sup -1}). The best activity occurs over Fe{sub 1.2}Cr{sub 0.8}O{sub 3} in SO{sub 3}{sup 2-} (0.1 M) solution with H{sub 2} liberation rate of 21.7 {mu}mol g{sup -1} min{sup -1} and a quantum yield 0.06% under polychromatic light. Over time, a pronounced deceleration occurs, due to the competitive reduction of the end product S{sub 2}O{sub 6}{sup 2-}. (author)

  13. Catalytic hydrogen production over RhPd/CeO2 catalysts and CO purification over Au/TiO2 catalysts

    OpenAIRE

    Jiménez Divins, Núria

    2015-01-01

    La consulta íntegra de la tesi, inclosos els articles no comunicats públicament per drets d'autor, es pot realitzar prèvia petició a l'Arxiu UPC This Thesis focuses on the study of the catalytic production of hydrogen from a biofuel, namely the bioethanol. It also studies the subsequent purification of pre-cleaned reformate streams. The end use of the hydrogen produced is to feed fuel cells to power portable and mobile applications. In this Thesis, two types of catalysts have been develope...

  14. Catalytic Hydrogenation of the Sweet Principles of Stevia rebaudiana, Rebaudioside B, Rebaudioside C, and Rebaudioside D and Sensory Evaluation of Their Reduced Derivatives

    OpenAIRE

    Mary Campbell; Indra Prakash; Venkata Sai Prakash Chaturvedula

    2012-01-01

    Catalytic hydrogenation of rebaudioside B, rebaudioside C, and rebaudioside D; the three ent-kaurane diterpene glycosides isolated from Stevia rebaudiana was carried out using Pd(OH)2. Reduction of steviol glycosides was performed using straightforward synthetic chemistry with the catalyst Pd(OH)2 and structures of the corresponding dihydro derivatives were characterized on the basis of 1D and 2D nuclear magnetic resonance (NMR) spectral data indicating that all are novel compounds being repo...

  15. Hydrogen-transfer and charge-transfer in photochemical and radiation induced reactions. Progress report, November 1, 1975--October 31, 1976

    International Nuclear Information System (INIS)

    The relative importance of light absorption, quenching of triplet, and hydrogen transfer repair has been examined in retardation by mercaptans of photoreduction of aromatic ketones by alcohols. In the reduction of benzophenone by 2-propanol, retardation is efficient and, after correction for the first two effects, is due entirely to hydrogen-transfer repair, as indicated by deuterium labeling. In reduction of acetophenone by α-methylbenzyl alcohol, repair by hydrogen transfer is also operative. In reduction of benzophenone by benzhydrol, retardation is less efficient and is due to quenching, as the ketyl radical does not abstract hydrogen from mercaptan rapidly in competition with coupling. Deuterium isotope effects are discussed in terms of competitive reactions. Photoreduction of benzophenone by 2-butylamine and by triethylamine is retarded by aromatic mercaptans and disulfides. Of the retardation not due to light absorption and triplet quenching by the sulfur compounds, half is due to hydrogen-transfer repair, as indicated by racemization and deuterium labeling. The remainder is attributed to quenching by the sulfur compound of the charge-transfer-complex intermediate. Photoreduction by primary and secondary amines, but not by tertiary amines, is accelerated by aliphatic mercaptans. The acceleration is attributed to catalysis of hydrogen transfer by the mercaptan in the charge-transfer complex. The effect is large in hydrocarbon solvent, less in polar organic solvents and absent in water

  16. Solar Photo Catalytic Hydrogen Production from water using a dual bed photosystem

    Energy Technology Data Exchange (ETDEWEB)

    Florida Solar Energy Center

    2003-03-30

    A body of work was performed in which the feasibility of photocatalytically decomposing water into its constituent elements using a dual bed, or modular photosystem, under solar radiation was investigated. The system envisioned consists of two modules, each consisting of a shallow, flat, sealed container, in which microscopic photocatalytic particles are immobilized. The photocatalysts absorb light, generating free electrons and lattice vacancy holes, which are capable of performing reductive and oxidative chemistry, respectively. The photocatalysts would be chosen as to whether they specifically promote H{sub 2} or O{sub 2} evolution in their respective containers. An aqueous solution containing a redox mediator is pumped between the two chambers in order to transfer electron equivalents from one reaction to the other.

  17. 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

  18. Transfer hydrogenation with abnormal dicarbene rhodium(iii) complexes containing ancillary and modular poly-pyridine ligands.

    Science.gov (United States)

    Farrell, Kevin; Melle, Philipp; Gossage, Robert A; Müller-Bunz, Helge; Albrecht, Martin

    2016-03-21

    Treatment of an abnormal dicarbene ligated rhodium(iii) dimer with 2,2'-bipyridine (bipy), 1,10-phenanthroline (phen) or 2,2':6',2''-terpyridine (terpy) results in coordination of the N-donor ligands and concomitant cleavage of the dimeric structure. Depending on the denticity of the pyridyl ligand, this situation retains one (L = terpy) or two (L = bipy, phen) flexible sites for substrate coordination. In the case of the bipy complexes, modification of the electron density at Rh, without directly affecting the steric environment about the metal centre, was achieved by the incorporation of electron-donating or electron-withdrawing substituents on the bipy backbone. The dicarbene pyridyl complexes were active in transfer hydrogenation catalysis of benzophenone at 0.15 mol% catalyst loading in a iPrOH/KOH mixture. The catalysts displayed a strong characteristic colour change (yellow to purple) after activation which allowed for visual monitoring of the status of the reaction. The colour probe and the robustness of the active catalysts proved useful for catalyst recycling. The catalytic activity sustained over five consecutive substrate batch additions and gave a maximum overall turnover number of 3100. PMID:26842739

  19. Green diesel production via catalytic hydrogenation/decarboxylation of triglycerides and fatty acids of vegetable oil and brown grease

    Science.gov (United States)

    Sari, Elvan

    than activated carbon itself for both decarboxylation of oleic acid and hydrogenation of alkenes. In an additional effort to reduce Pd amount in the catalyst, Pd2Co/C catalysts with various Pd content were prepared and the catalytic activity study showed that 0.5 wt% Pd2Co/C catalyst performs even better than a 5 wt% Pd/C catalyst. Pd and Co alloys were very well dispersed and formed fine clusters, which led to a higher active metal surface area and hence favored the decarboxylation of oleic acid. This study showed that an alloy of Pd on carbon with a significantly low Pd content is much more active and selective to diesel hydrocarbons production from an unsaturated fatty acid in super-critical water and may be regarded as a prospective feasible decarboxylation catalyst for the removal of oxygen from vegetable oil/animal fat without the need of additional hydrogen.

  20. THE ASYMMETRIC SYNTHESIS OF AMINO ACIDS UNDER POLYMER-SUPPORTED PHASE TRANSFER CATALYTIC CONDITION

    Institute of Scientific and Technical Information of China (English)

    1998-01-01

    The optical α-amino acids were synthesized under room temperature by alkylation of N-(diphenyl methylene) glycine t-butyl ester under polymer-supported phase transfer conditions using polymer-supported cinchonine (or quinine) alkaloids as chiral phase transfer catalysts and dichloromethane as solvent, followed by hydrolysis of the above intermediates introduced to the final products-optical α-amino acids. This is a new method for the asymmetric synthesis of α-amino acids. The influences of catalyst,temperature, substrates, and organic solvents on the chemical yield and optical purities of products were studied.

  1. 催化点火气氢气氧推力器试验研究%Experimental Investigation on Catalytic Hydrogen and Oxygen Thruster

    Institute of Scientific and Technical Information of China (English)

    林震; 王长辉; 刘宇

    2012-01-01

    为探索催化点火气氢气氧推力器的点火规律和相关性能,设计并搭建了1N催化点火气氢气氧推力器试验系统,进行了冷热试试验。试验成功实现了不同工况下的多次催化点火。结果表明:供给氧氢混合比控制在100时,推力器预燃室产生的点火温度为700℃,能够满足燃烧室点火要求;催化剂面积体积比对催化氢氧点火具有决定性影响,采用面积体积比大的催化载体可以实现常温(8℃)下的催化点火;另外,试验中氢氧燃烧产生的高温和试验结束后推力器内残留的液态水也对催化组件提出了一定的耐温性和防水性要求。%In order to study the catalytic ignition law of catalytic hydrogen and oxygen thruster, a 1N catalytic thruster and relative experimental system were constructed. A series of tests were conducted. Several catalytic ignition in different working condition was realized. It indicates that when the oxygen and hydrogen mixture ratio is 100, the measured temperature of pre- combustion is 700℃ , which is the most applicable ignition temperature. Catalytic ignition in normal temperature can be real- ized using palladium-carbon as catalyzer which shows the domination of surface-volume ratio for catalytic ignition. In addition, it indicates that the ability of fireproof and waterproof is also the key characteristics of the catalyzer parts for catalytic hydrogen and oxwen thruster.

  2. In-Cylinder Heat Transfer Characteristics of Hydrogen Fueled Engine: A Steady State Approach

    Directory of Open Access Journals (Sweden)

    M. M. Rahman

    2010-01-01

    Full Text Available This study presents in-cylinder heat transfer characteristics of a single cylinder port injection Hydrogen fueled Internal Combustion Engine (H2ICE using a steady state approach. Problem statement: The differences in characteristics between hydrogen and hydrocarbon fuels are led to the difference in the behavior of physical processes during engine cycle. One of these processes is the in-cylinder heat transfer. Approach: One dimensional gas dynamic model was used to describe the heat transfer characteristics of the engine. The engine speed was varied from 2000-5000 rpm, crank angle from -40° to +100°, while Air-Fuel Ratio (AFR was changed from stoichiometric to lean limit. Results: The simulated results showed higher heat transfer rate but lower heat transfer to total fuel energy ratio with increasing the engine speed. The in-cylinder pressure and temperature were increased with decreasing AFR and increasing engine speed. The in-cylinder air flow rate was increased linearly with increasing engine speed as well as air fuel ratio. Conclusion/Recommendations: The results showed that the AFR has a vital effect on characteristics variation while the engine speed has minor effect. These results can be utilized for the study of combustion process, fuel consumption, emission production and engine performance.

  3. The treatment of wasted gas in GC hydrogen isotope separation

    International Nuclear Information System (INIS)

    The ways used to treat wasted gas in GC hydrogen isotope separation were introduced. Catalytic oxidation and cryogenic absorption which can be applied to circle run separation system were introduced emphatically. The result of experiment shows that in catalytic oxidation system without air or oxygen, little hydrogen in helium was deleted, but 99.99%-99.999% helium can be produced when a mass of air was added to the gas flow and that in cryogenic absorption system, 98% hydrogen and 99% helium was produced without any additional treatment, such hydrogen can be used in hydrogen-oxygen combination reaction, after next treatment, such helium can be used as transferring gas. (authors)

  4. Electrocatalytic Hydrogen Production by an Aluminum(III) Complex: Ligand-Based Proton and Electron Transfer.

    Science.gov (United States)

    Thompson, Emily J; Berben, Louise A

    2015-09-28

    Environmentally sustainable hydrogen-evolving electrocatalysts are key in a renewable fuel economy, and ligand-based proton and electron transfer could circumvent the need for precious metal ions in electrocatalytic H2 production. Herein, we show that electrocatalytic generation of H2 by a redox-active ligand complex of Al(3+) occurs at -1.16 V vs. SCE (500 mV overpotential). PMID:26249108

  5. Do Spin State and Spin Density Affect Hydrogen Atom Transfer Reactivity?

    OpenAIRE

    Saouma, Caroline T.; Mayer, James M.

    2013-01-01

    The prevalence of hydrogen atom transfer (HAT) reactions in chemical and biological systems has prompted much interest in establishing and understanding the underlying factors that enable this reactivity. Arguments have been advanced that the electronic spin state of the abstractor and/or the spin-density at the abstracting atom are critical for HAT reactivity. This is consistent with the intuition derived from introductory organic chemistry courses. Herein we present an alternative view on t...

  6. 2D-IR spectroscopy of hydrogen-bond-mediated vibrational excitation transfer.

    Science.gov (United States)

    Chuntonov, Lev

    2016-05-18

    Vibrational excitation transfer along the hydrogen-bond-mediated pathways in the complex of methyl acetate (MA) and 4-cyanophenol (4CP) was studied by dual-frequency femtosecond two-dimensional infrared spectroscopy. We excited the energy-donating ester carbonyl stretching vibrational mode and followed the transfer to the energy-accepting benzene ring and cyano stretching vibrations. The complexes with no, one, and two hydrogen-bonded 4CP molecules were studied. Vibrational relaxation of the carbonyl mode is more efficient in both hydrogen-bonded complexes as compared with free MA molecules. The inter-molecular transport in a hydrogen-bonded complex involving a single 4CP molecule is slower than that in a complex with two 4CP molecules. In the former, vibrational relaxation leads to local heating, as shown by the spectroscopy of the carbonyl mode, whereas the local heating is suppressed in the latter because the excitation redistribution is more efficient. At early times, the transfer to the benzene ring is governed by its direct coupling with the energy-donating carbonyl mode, whereas at later times intermediate states are involved. The transfer to a more distant site of the cyano group in 4CP involves intermediate states at all times, since no direct coupling between the energy-donating and accepting modes was observed. We anticipate that our findings will be of importance for spectroscopic studies of bio-molecular structures and dynamics, and inter- and intra-molecular signaling pathways, and for developing molecular networking applications. PMID:27145861

  7. Direct 'in situ', low VOC, high yielding, CO2 expanded phase catalytic chain transfer polymerisation: towards scale-up.

    Science.gov (United States)

    Adlington, Kevin; Green, Anthony; Wang, Wenxin; Howdle, Steven M; Irvine, Derek J

    2013-01-01

    The successful application of catalytic chain transfer polymerisation (CCTP) by adopting an 'in situ' catalyst preparation methodology in several polymerisation media is described. More specifically, this study is focused on reporting the development of 'in situ' CCTP within a CO(2) expanded phase polymerisation process, which achieved high yields of polymer whilst minimising both VOC footprint and CO(2) compression costs. The 'in situ' method is shown to be effective in controlling polymerisations conducted in both conventional solvents and bulk under inert atmosphere, delivering molecular weight reductions and a Cs value of appropriate similar magnitude to those achieved by the benchmark, commercially sourced CoPhBF catalyst. The 'in situ' effect has been achieved with equal efficiency when both using catalysts with different axial ligands and where the complex is required to undergo a facile ligand dissociation in order to create the required catalyst necessary to achieve CCTP control. Furthermore, both catalysts are shown to effectively control polymerisations in a CO(2) expanded phase process, in which a small amount of compressed CO(2) is introduced to reduce the viscosity of the reaction mixture, allowing for easy heat transfer and good catalyst diffusion during reaction. In this way, yield limitations imposed to avoid the Trommsdorff effect required in bulk processing and the need for post precipitation have been successfully overcome. Both of these factors further improve the sustainability of such a polymerisation process. However, the 'in situ', high pressure expanded phase environment was observed to retard the ligand dissociation required for catalyst activation. PMID:23085824

  8. Hydrogen production by steam reforming of bio-alcohols. The use of conventional and membrane-assisted catalytic reactors

    Energy Technology Data Exchange (ETDEWEB)

    Seelam, P. K.

    2013-11-01

    The energy consumption around the globe is on the rise due to the exponential population growth and urbanization. There is a need for alternative and non-conventional energy sources, which are CO{sub 2}-neutral, and a need to produce less or no environmental pollutants and to have high energy efficiency. One of the alternative approaches is hydrogen economy with the fuel cell (FC) technology which is forecasted to lead to a sustainable society. Hydrogen (H{sub 2}) is recognized as a potential fuel and clean energy carrier being at the same time a carbon-free element. Moreover, H{sub 2} is utilized in many processes in chemical, food, metallurgical, and pharmaceutical industry and it is also a valuable chemical in many reactions (e.g. refineries). Non-renewable resources have been the major feedstock for H{sub 2} production for many years. At present, {approx}50% of H{sub 2} is produced via catalytic steam reforming of natural gas followed by various down-stream purification steps to produce {approx}99.99% H{sub 2}, the process being highly energy intensive. Henceforth, bio-fuels like biomass derived alcohols (e.g. bio-ethanol and bio-glycerol), can be viable raw materials for the H{sub 2} production. In a membrane based reactor, the reaction and selective separation of H{sub 2} occur simultaneously in one unit, thus improving the overall reactor efficiency. The main motivation of this work is to produce H{sub 2} more efficiently and in an environmentally friendly way from bio-alcohols with a high H{sub 2} selectivity, purity and yield. In this thesis, the work was divided into two research areas, the first being the catalytic studies using metal decorated carbon nanotube (CNT) based catalysts in steam reforming of ethanol (SRE) at low temperatures (<450 deg C). The second part was the study of steam reforming (SR) and the water-gas-shift (WGS) reactions in a membrane reactor (MR) using dense and composite Pd-based membranes to produce high purity H{sub 2}. CNTs

  9. Vectorial electron transfer for improved hydrogen evolution by mercaptopropionic-acid-regulated CdSe quantum-dots-TiO2 -Ni(OH)2 assembly.

    Science.gov (United States)

    Yu, Shan; Li, Zhi-Jun; Fan, Xiang-Bing; Li, Jia-Xin; Zhan, Fei; Li, Xu-Bing; Tao, Ye; Tung, Chen-Ho; Wu, Li-Zhu

    2015-02-01

    A visible-light-induced hydrogen evolution system based on a CdSe quantum dots (QDs)-TiO2 -Ni(OH)2 ternary assembly has been constructed under an ambient environment, and a bifunctional molecular linker, mercaptopropionic acid, is used to facilitate the interaction between CdSe QDs and TiO2 . This hydrogen evolution system works effectively in a basic aqueous solution (pH 11.0) to achieve a hydrogen evolution rate of 10.1 mmol g(-1)  h(-1) for the assembly and a turnover frequency of 5140 h(-1) with respect to CdSe QDs (10 h); the latter is comparable with the highest value reported for QD systems in an acidic environment. X-ray photoelectron spectroscopy, X-ray absorption spectroscopy, and control experiments demonstrate that Ni(OH)2 is an efficient hydrogen evolution catalyst. In addition, inductively coupled plasma optical emission spectroscopy and the emission decay of the assembly combined with the hydrogen evolution experiments show that TiO2 functions mainly as the electron mediator; the vectorial electron transfer from CdSe QDs to TiO2 and then from TiO2 to Ni(OH)2 enhances the efficiency for hydrogen evolution. The assembly comprises light antenna CdSe QDs, electron mediator TiO2 , and catalytic Ni(OH)2 , which mimics the strategy of photosynthesis exploited in nature and takes us a step further towards artificial photosynthesis. PMID:25470751

  10. Catalytic activity of iron hexacyanoosmate(II) towards hydrogen peroxide and nicotinamide adenine dinucleotide and its use in amperometric biosensors

    Energy Technology Data Exchange (ETDEWEB)

    Kotzian, Petr; Janku, Tereza [Department of Analytical Chemistry, University of Pardubice, Nam. Cs. Legii 565, CZ-532 10 Pardubice (Czech Republic); Kalcher, Kurt [Institute of Chemistry - Analytical Chemistry, Karl-Franzens University, Universitaetsplatz 1, A-8010 Graz (Austria); Vytras, Karel [Department of Analytical Chemistry, University of Pardubice, Nam. Cs. Legii 565, CZ-532 10 Pardubice (Czech Republic)], E-mail: karel.vytras@upce.cz

    2007-09-19

    Hydrogen peroxide and nicotinamide adenine dinucleotide (NADH) may be determined amperometrically using screen-printed electrodes chemically modified with iron(III) hexacyanoosmate(II) (Osmium purple) in flow injection analysis (FIA). The determination is based on the exploitation of catalytic currents resulting from the oxidation/reduction of the modifier. The performance of the sensor was characterized and optimized by controlling several operational parameters (applied potential, pH and flow rate of the phosphate buffer). Comparison has been made with analogous complexes of ruthenium (Ruthenium purple) and iron (Prussian blue). Taking into account the sensitivity and stability of corresponding sensors, the best results were obtained with the use of Osmium purple. The sensor exhibited a linear increase of the amperometric signal with the concentration of hydrogen peroxide in the range of 0.1-100 mg L{sup -1} with a detection limit (evaluated as 3{sigma}) of 0.024 mg L{sup -1} with a R.S.D. 1.5% for 10 mg L{sup -1} H{sub 2}O{sub 2} under optimized flow rate of 0.4 mL min{sup -1} in 0.1 M phosphate buffer carrier (pH 6) and a working potential of +0.15 V versus Ag/AgCl. Afterwards, a biological recognition element - either glucose oxidase or ethanol dehydrogenase - was incorporated to achieve a sensor facilitating the determination of glucose or ethanol, respectively. The glucose sensor gave linearity between current and concentration in the range from 1 to 250 mg L{sup -1} with a R.S.D. 2.4% for 100 mg L{sup -1} glucose, detection limit 0.02 mg L{sup -1} (3{sigma}) and retained its original activity after 3 weeks when stored at 6 deg. C. Optimal parameters in the determination of ethanol were selected as: applied potential +0.45 V versus Ag/AgCl, flow rate 0.2 mL min{sup -1} in 0.1 M phosphate buffer carrier (pH 7). Different structural designs of the ethanol sensor were tested and linearity obtained was up to 1000 mg L{sup -1} with a maximum R.S.D. of 5

  11. Molecular hydrogen and catalytic combustion in the production of hyperpolarized 83Kr and 129Xe MRI contrast agents.

    Science.gov (United States)

    Rogers, Nicola J; Hill-Casey, Fraser; Stupic, Karl F; Six, Joseph S; Lesbats, Clémentine; Rigby, Sean P; Fraissard, Jacques; Pavlovskaya, Galina E; Meersmann, Thomas

    2016-03-22

    Hyperpolarized (hp)(83)Kr is a promising MRI contrast agent for the diagnosis of pulmonary diseases affecting the surface of the respiratory zone. However, the distinct physical properties of(83)Kr that enable unique MRI contrast also complicate the production of hp(83)Kr. This work presents a previously unexplored approach in the generation of hp(83)Kr that can likewise be used for the production of hp(129)Xe. Molecular nitrogen, typically used as buffer gas in spin-exchange optical pumping (SEOP), was replaced by molecular hydrogen without penalty for the achievable hyperpolarization. In this particular study, the highest obtained nuclear spin polarizations wereP =29% for(83)Kr andP= 63% for(129)Xe. The results were reproduced over many SEOP cycles despite the laser-induced on-resonance formation of rubidium hydride (RbH). Following SEOP, the H2was reactively removed via catalytic combustion without measurable losses in hyperpolarized spin state of either(83)Kr or(129)Xe. Highly spin-polarized(83)Kr can now be purified for the first time, to our knowledge, to provide high signal intensity for the advancement of in vivo hp(83)Kr MRI. More generally, a chemical reaction appears as a viable alternative to the cryogenic separation process, the primary purification method of hp(129)Xe for the past 2 1/2 decades. The inherent simplicity of the combustion process will facilitate hp(129)Xe production and should allow for on-demand continuous flow of purified and highly spin-polarized(129)Xe. PMID:26961001

  12. Molecular hydrogen and catalytic combustion in the production of hyperpolarized 83Kr and 129Xe MRI contrast agents

    Science.gov (United States)

    Rogers, Nicola J.; Hill-Casey, Fraser; Stupic, Karl F.; Six, Joseph S.; Lesbats, Clémentine; Rigby, Sean P.; Fraissard, Jacques; Pavlovskaya, Galina E.; Meersmann, Thomas

    2016-03-01

    Hyperpolarized (hp) 83Kr is a promising MRI contrast agent for the diagnosis of pulmonary diseases affecting the surface of the respiratory zone. However, the distinct physical properties of 83Kr that enable unique MRI contrast also complicate the production of hp 83Kr. This work presents a previously unexplored approach in the generation of hp 83Kr that can likewise be used for the production of hp 129Xe. Molecular nitrogen, typically used as buffer gas in spin-exchange optical pumping (SEOP), was replaced by molecular hydrogen without penalty for the achievable hyperpolarization. In this particular study, the highest obtained nuclear spin polarizations were P = 29% for 83Kr and P = 63% for 129Xe. The results were reproduced over many SEOP cycles despite the laser-induced on-resonance formation of rubidium hydride (RbH). Following SEOP, the H2 was reactively removed via catalytic combustion without measurable losses in hyperpolarized spin state of either 83Kr or 129Xe. Highly spin-polarized 83Kr can now be purified for the first time, to our knowledge, to provide high signal intensity for the advancement of in vivo hp 83Kr MRI. More generally, a chemical reaction appears as a viable alternative to the cryogenic separation process, the primary purification method of hp 129Xe for the past 2 1/2 decades. The inherent simplicity of the combustion process will facilitate hp 129Xe production and should allow for on-demand continuous flow of purified and highly spin-polarized 129Xe.

  13. Hydrogen production from catalytic decomposition of methane; Produccion de hidrogeno a partir de la descomposicion termica catalitica del biogas de digestion anaerobia

    Energy Technology Data Exchange (ETDEWEB)

    Belsue Echevarria, M.; Etxebeste Juarez, O.; Perez Gil, S.

    2002-07-01

    The need of substitution of part of the energy obtained from fossil fuels instead of energy from renewable sources, together with the minimal emissions of CO{sub ''} and CO that are expected with these technologies, make renewable sources a very attractive predecessor for the production of hydrogen. In this situation, a usable source for hydrogen production is the biogas achieved by means of technologies like the anaerobic digestion of different kinds of biomass (MSW, sewage sludge, stc.). In this article we suggest the Thermal Catalytic Decomposition of the methane contained in this biogas, after separation of pollutants like CO{sub ''}, H{sub 2}S. steam. This technology will give hydrogen, usable in fuel cells, and nanoestructured carbon as products. (Author) 7 refs.

  14. Progress in Asymmetric Hydrogenation and Transfer Hydrogenation in Aqueous Media%水相不对称氢化及转移氢化反应研究进展

    Institute of Scientific and Technical Information of China (English)

    隋岩; 朱敏; 付雯

    2008-01-01

      Water has many advantages over the usual organic solvents in the catalytic reactions, for its safety, economy and no environmental pollution. From the industrial application point of view, the use of a two-phase system allows an easy separation of the products from the poisonous and usually expensive catalysts by simple phase separation. In this paper, the progress in organometallic-catalyzed asymmetric hydrogenation and transfer hydrogenation in aqueous media is reviewed. The emphasis is laid on the asymmetric hydrogenation and transfer hydrogenation of prochiral substrates such asα-acetamidoacrylic acid esters andβ-ketoesters in water. Their application is anticipated.%  在催化反应中以水代替常用的有机溶剂具有安全、经济、无环境污染等优点,而且在工业应用上,使用两相体系可以在反应完成之后,通过简单的相分离分离出产物和回收有毒的通常也是昂贵的催化剂,因此具有重要意义。本文综述了近年来以水为溶剂的不对称氢化及转移氢化反应的研究进展,重点介绍了前手性底物α-氨基丙烯酸酯及前手性酮的水相不对称氢化及转移氢化反应,并对其应用前景进行了展望。

  15. Specific features of hydrogen boiling heat transfer on the AMg-6 alloy massive heater

    International Nuclear Information System (INIS)

    Heat transfer and nucleate burns-out saturated with hydrogen at a plate heater (thickness-13 mm, diameter of heat-transferring surface - 30 mm) made of an aluminium alloy with the low value of a heat assimilation coefficient in the pressure range from 7.2x103 to 6x105 Pa is experimentally investigated. Value of start of boiling characteristics and heat transfer coefficients during nucleate burn-out, as well as the first critical densities of a heat flux and temperature heads are obtained. Existence of certain differrences of heat exchange during boiling is shown using a massive heater made of low-heat-conductive material in comparison with other cases of hydrogen boiling. Hypothesis concerning the existence of so-called mixed boiling on the heat transfer surface, which has been detected earlier only in helium boiling, as well as concerning possible reasons of stability of film boiling ficii in preburn-out region of heat duty is discussed

  16. An FTIR study on the catalytic effect of water molecules on the reaction of CO successive hydrogenation at 3 and 10K

    Science.gov (United States)

    Pirim, C.; Krim, L.

    2011-05-01

    The ubiquitous presence of water and the relative high abundance of H2, H and CO molecules in the interstellar medium motivated numerous studies on their potential interaction. The reaction of successive hydrogenation of CO is of large interest in astrochemistry because of its implication in the formation of formaldehyde and methanol in interstellar grains and in comets. The catalytic effect of water on the successive hydrogenation of CO has been investigated by two methods. The first is the hydrogenation of a CO/H2O surface. The second is a co-injection of (CO/H2O) mixtures and H atoms. Both methods have been performed at 3 and 10 K. When the hydrogenation of a CO surface is performed at 3 K, no products are observed. In fact, the presence of solid hydrogen screens the hydrogenation process. However, when performed at 10 K, the experiment shows that water molecules increase the concentration of the H2CO and CH3OH species. At 3 and 10K, [(CO/H2O)+H] co-depositions confirm a subtantial impact on by-products formation. We show that water molecules increase the probability of reactive to encounter H atoms either physically, or chemically, by raising the number of chemical pathways. A coordinated theoretical study of the possible chemical pathways is currently under way.

  17. Study of reactive transfer of hydrogen within intact clay-rock

    International Nuclear Information System (INIS)

    Hydrogen gas will be produced by anaerobic corrosion of radioactive waste containers in the geological repository. This gas could affect the geological layer (Callovo-Oxfordian) stability, first due to its reductive capacity and then also due to its continuous production for about 100,000 years. The local pressure increase could affect the properties of hydro-gaseous dynamic of hydrogen transfers. The reductive capacity of H2 could change the redox properties of the Callovo-Oxfordian and the barrier hydraulic properties, and therefore (1) its mineralogy, (2) the speciation of outgoing radionuclides and (3) their transfer. Moreover, if the hydrogen gas transport is difficult within the geological layer, the pressure increase could cause cracking and create preferential pathways for radionuclides migration. An experimental device was developed to measure the entry pressure of H2(g) and transport parameters as permeability and diffusion coefficient through the COx. The entry pressure is estimated to be between 49 and 63 bar. Knowing that the maximum expected pressure is about 80 bar, there may therefore be a displacement of hydrogen gas into the water saturated clay-rock. Moreover, for a saturation greater than 0.90 and at T = 23 C, permeability is measured to be close to 10-23 m2 and the diffusion coefficient to be as low as 10-12 m2.s-1. Therefore hydrogen gas will move slowly in the geological layer, for example it will take about 31,710 years to go through one meter of clay-rock by diffusion. These transport parameters are found to depend mainly on the sample water saturation and not much on temperature. Regarding hydrogen reactivity, under conditions close to those in the storage, H2 will reduce up to 9 wt% of structural Fe (III) at 90 C and PH2 = 5 bar. This reaction is not complete and hydrogen gas will mainly sorb on the material, with a sorption up to 0.05 wt% at 90 C and PH2 = 0.45 bar. This process depends strongly on the water saturation of the sample

  18. Microscopic models for proton transfer in water and strongly hydrogen-bonded complexes with a single-well proton potential

    DEFF Research Database (Denmark)

    Kuznetsov, A.M.; Ulstrup, Jens

    2004-01-01

    A new mechanism and formalism for proton transfer in donor-acceptor complexes with long hydrogen bonds introduced recently [1], is applied to a proton transfer in liquid water. "Structural diffusion" of hydroxonium ions is regarded as totally adiabatic process, with synchronous hindered translation...... of two closest water molecules to and from the reaction complex as crucial steps. The water molecules induce a "gated" shift of the proton from the donor to the acceptor in the double-well potential with simultaneous breaking/formation of hydrogen bonds between these molecules and the proton donor...... hydrogen-bonded donor-acceptor complexes. In contrast to the above model [1], the short hydrogen bond between the donor and acceptor moieties, however, completely erodes the barrier along the proton transfer mode. This introduces some physical pattern differences from proton transfer reactions in truly...

  19. Evidence for alkali metal induced intermolecular acetylenic hydrogen atom transfer between hydrogen-bonded alkyne complexes in solid argon

    International Nuclear Information System (INIS)

    Condensation of acetylene, propyne, and 2-butyne/acetylene mixtures with heavy alkali metal atoms (Na, K, Cs) in an argon matrix at 15 K has led to the appearance of infrared absorptions due to ethylene, propylene, and trans-2-butene, respectively. These results stand in sharp contrast with the products obtained with lithium. Isotopic studies have shown that ethylene formation involved three different acetylene molecules and evidenced a difference in the product yield with hydrogen vs. deuterium as well as a preference for trans- vs. cis-C2H2D2 formation, which is discussed and rationalized by differences in the zero point energies for the different mixed deuterium isotopes of the intermediate vinyl radical. This trend is amplified by methyl substitution. Spectroscopic evidence was found in these experiments for cesium acetylide (Cs+C2H-) and a cesium-acetylene π complex, which are involved in the intermolecular acetylenic hydrogen atom transfer process. 26 references, 3 figures, 2 tables

  20. Catalytic De/hydrogenation in Mg by co-doped Ni and VO{sub x} on active carbon: extremely fast kinetics at low temperatures and high hydrogen capacity

    Energy Technology Data Exchange (ETDEWEB)

    Jia, Yi; Cheng, Lina [ARC Centre of Excellence for Functional Nanomaterials, University of Queensland, Brisbane (Australia); School of Mechanical and Mining Engineering, University of Queensland, Brisbane (Australia); Pan, Nan [Hefei National Laboratory for Physical Sciences at Microscale, University of Science and Technology of China, Hefei (China); Zou, Jin [School of Mechanical and Mining Engineering, University of Queensland, Brisbane (Australia); Lu, Gaoqing (Max) [ARC Centre of Excellence for Functional Nanomaterials, University of Queensland, Brisbane (Australia); Yao, Xiangdong [ARC Centre of Excellence for Functional Nanomaterials, University of Queensland, Brisbane (Australia); Queensland Micro- and Nanotechnology Centre (QMNC), Griffith University, Brisbane (Australia)

    2011-05-15

    A multi-component catalyst Ni-VO{sub x}/AC (VO{sub x} is comprised of V{sub 2}O{sub 5} and VO{sub 2}, x = 2.18) was synthesized by a wet impregnation method. The synthesized Ni-VO{sub x}/AC shows a superior catalytic effect on de/hydrogenation of Mg. The MgH{sub 2}+Ni-VO{sub x}/AC composites can absorb 6.2 wt.-% hydrogen within only 1 min at 150 C under a hydrogen pressure of 2 MPa and desorb 6.5 wt.-% hydrogen within 10 min at 300 C under an initial hydrogen pressure of 1 KPa, which overcomes a critical barrier for practical use of Mg as a hydrogen storage material. A significant decrease of activation energy (E{sub a}) indicates that Ni-VO{sub x}/AC catalyst is highly efficient for Mg de/hydrogenation, which may be ascribed to the synergistic effect of bimetals (metal oxides) and nanocarbon. (Copyright copyright 2011 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  1. Influence of different preparation conditions on catalytic activity of ag /gama-al/sub 2/o/sub 3/ for hydrogenation of coal slime pyrolysis

    International Nuclear Information System (INIS)

    This paper, introducing variable conditional factors with Ag/AL/sub 2/O/sub 3/ as catalyst, selects five variables to investigate the influences of experimental conditions on Ag/Al2O/sub 3/ catalytic activity and define the optimal process conditions. These variables include Ag loading amount, calcinations temperature, calcinations time, reduction temperature, reduction time. X ray diffraction (XRD), hydrogen temperature-programmed reduction (TPR), X ray photoelectron spectrum (XPS) and scanning electron microscopy (SEM) were utilized to characterize the catalytic activity of Ag/-Al/sub 2/O/sub 3/, active center structure and state and those of carrier were emphatically studied, In the meantime the effects of active center and carrier on catalytic activity are studied. The results showed that: (1) In the range of 600 degree C-900 degree C, the catalytic activity of Ag/-Al/sub 2/O/sub 3/ with different loading showed little difference when changing loading amount, in the range of 900 degree C-1100 degree C, when the loading was 5%, the catalytic activity was very high; From the XRD and SEM characterizations, when the loading was 5%, it showed strong intensity diffraction peak of Ag crystal, crystal Ag is the most important activity center to promote hydrogen yield. (2) the catalytic activity of Ag/-Al/sub 2/O/sub 3/ at 450 degree C was considerably higher than that at 400 degree C and 500 degree C. By BET, XRD and SEM characterization, it can be seen, the diffraction peaks intensity of Ag crystal at 450 degree C is higher and sharper than that at 400 degree C and 500 degree C and with the increase of calcinations temperature, the specific surface area of catalysts also increased. (3) In the range of 600 degree C - 1000 degree C, the effects of calcinations time can be negligible, while, with temperature higher than 1000 degree C, 4-hour-calcinations-time catalyst exhibits a more noticeable catalytic activity than 3-hour and 5-hour catalyst do; From the XRD

  2. Transfer Hydrogenation Employing Ethylene Diamine Bisborane in Water and Pd- and Ru-Nanoparticles in Ionic Liquids

    Directory of Open Access Journals (Sweden)

    Sebastian Sahler

    2015-09-01

    Full Text Available Herein we demonstrate the use of ethylenediamine bisborane (EDAB as a suitable hydrogen source for transfer hydrogenation reactions on C-C double bonds mediated by metal nanoparticles. Moreover, EDAB also acts as a reducing agent for carbonyl functionalities in water under metal-free conditions.

  3. Intermolecular hydrogen bonds: From temperature-driven proton transfer in molecular crystals to denaturation of DNA

    Indian Academy of Sciences (India)

    Mark Johnson

    2008-11-01

    We have combined neutron scattering and a range of numerical simulations to study hydrogen bonds in condensed matter. Two examples from a recent thesis will be presented. The first concerns proton transfer with increasing temperature in short inter-molecular hydrogen bonds [1,2]. These bonds have unique physical and chemical properties and are thought to play a fundamental role in processes like enzymatic catalysis. By combining elastic and inelastic neutron scattering results with ab initio, lattice dynamics and molecular dynamics simulations, low frequency lattice modes are identified which modulate the potential energy surface of the hydrogen bond proton and drive proton transfer. The second example concerns base-pair opening in DNA which is the fundamental physical process underlying biological processes like denaturation and transcription. We have used an emprical force field and a large scale, all-atom phonon calculation to gain insight into the base-pair opening modes and the apparent `energy gap' between the accepted frequencies for these modes (∼ 100 cm-1 or ∼ 140 K) and the temperature of the biological processes (room temperature to 100° C) [3]. Inelastic neutron scattering spectra on aligned, highly crystalline DNA samples, produced at the ILL, provide the reference data for evaluating the precision of these simulation results.

  4. Precipitation and calcination synthesis methods forming nano-sized platinum catalytic particles for methanol and hydrogen oxidation

    Science.gov (United States)

    Naidoo, S.; Naidoo, Q.; Musil, E.; Linkov, V.; Vaivars, G.

    2013-03-01

    Under varying experimental conditions of calcination and precipitation reactions, different particle sizes and levels of platinum on carbon supported (Pt/C) catalysts were obtained. Rapid precipitation following a chemical reaction ensured formation of nano-sized catalytic particles using super-saturated concentrations under controlled conditions was a significant contribution in understanding the synthesis process and how it relates to an increased number of catalytic reaction sites ultimately providing superior electrochemical (EC) activity. These conditions influenced nucleation and growth rates of the catalytic particles. The super-saturation concentrations of the reactants in the reaction vessel played a direct role in producing the desired morphology of the crystallites.

  5. Numerical simulation of coupled heat and mass transfer in metal hydride-based hydrogen storage reactor

    International Nuclear Information System (INIS)

    In this paper, a numerical investigation of two-dimensional heat and mass transfer during absorption of hydrogen in a cylindrical metal hydride bed containing MmNi6.4Al0.4 is presented. By considering the variation in cooling fluid temperature along the axial direction (variable wall temperature), the changes in hydrogen concentration, hydride equilibrium pressure, and average hydride bed temperature at different axial locations are presented. The average bed temperature profiles and hydrogen storage capacities at different supply pressures showed good agreement with the experimental data reported in the literature. As the absorption progresses, the change in cooling fluid temperature along the axial direction is found to decrease and becomes unchanged at the end of the absorption process. The effect of variable wall temperature on hydrogen absorption rate for different supply pressures and hydride bed thicknesses are presented. The effect of variable wall temperature on absorption time is found to be significant for the hydride beds of thickness of above 7.5 mm. For a supply pressure of 20 bar, the maximum difference in absorption time between variable wall temperature and constant wall temperature boundary conditions is about 300 s for 17.5 mm bed thickness

  6. Natural spectroscopic hydrogen isotope transfer in alcohol dehydrogenase-catalysed reduction

    International Nuclear Information System (INIS)

    The enantiomeric purity of natural α-mono deuterated enantiomers, (R) and (S)ethanol-1-d1, in the alcohol produced by sugar fermentation with yeast was studied by 2H NMR using their esters derived from optical mandelic acid. The results of isotope tracing experiments show that the transfer pathways of the two eantiotopic hydrogens of the methylene group are different. It was observed that (S)-deuterium comes only from the medium water. The (R)-deuterium transferred by NADH in alcohol dehydrogenase reduction of the acetaldehyde is complex origin. Some of them originates from carbon bound hydrogen of the sugar, especially from C(4) position of glucose and most of them comes from water. Only a small portion of the NADH deuterium is incorporated indirectly from water through enzyme catalysed exchange between the pro-S site of NADH and flavin. When a carbonyl compound (ethyl acetoacetate) was reduced under the same conditions during the alcoholic fermentation, among the NADH-transferred deuterium, only a small portion comes from water while most comes from the unexchangeable positions of the glucose. (author)

  7. Radiative transfer in cylindrical threads with incident radiation VI. A hydrogen plus helium system

    CERN Document Server

    Gouttebroze, Pierre

    2009-01-01

    Spectral lines of helium are commonly observed on the Sun. These observations contain important informations about physical conditions and He/H abundance variations within solar outer structures. The modeling of chromospheric and coronal loop-like structures visible in hydrogen and helium lines requires the use of appropriate diagnostic tools based on NLTE radiative tranfer in cylindrical geometry. We use iterative numerical methods to solve the equations of NLTE radiative transfer and statistical equilibrium of atomic level populations. These equations are solved alternatively for the hydrogen and helium atoms, using cylindrical coordinates and prescribed solar incident radiation. Electron density is determined by the ionization equilibria of both atoms. Two-dimension effects are included. The mechanisms of formation of the principal helium lines are analyzed and the sources of emission inside the cylinder are located. The variations of spectral line intensities with temperature, pressure, and helium abundan...

  8. Catalytic thermal decomposition of methane to COx-free hydrogen and carbon nanotubes over MgO supported bimetallic group VIII catalysts

    International Nuclear Information System (INIS)

    Graphical abstract: - Highlights: • Bimetallic of group VIII/MgO catalysts were tested for methane decomposition reaction. • Fe–Co/MgO catalyst showed superior activity and stability toward H2 production. • Both Ni–Fe and Ni–Co catalysts exhibited lower catalytic activities. • The formation of MgxNi(1−x)O leads to the inhibition of catalytic activity. • High quality MWCNTs were obtained over all binary catalysts. - Abstract: Bimetallic Ni–Fe, Ni–Co and Fe–Co supported on MgO catalysts with a total metals content of 50 wt.% were evaluated for decomposition of methane to CO/CO2 free hydrogen and carbon nanomaterials. The catalytic runs were carried out at 700 °C under atmospheric pressure using fixed bed horizontal flow reactor. The materials were characterized by XRD, TEM, Raman spectroscopy, surface analysis and TGA–DTG. The data showed that the bimetallic 25% Fe–25%Co/MgO catalyst exhibited remarkable higher activity and stability up to ∼10 h time-on-stream with respect to H2 production. However, the catalytic activity and durability was greatly declined after incorporating 25%Ni to either 25%Fe or 25%Co/MgO catalysts at all time on stream. The main reason for the catalytic inhibition of Ni containing catalysts is consuming NiO during the formation of rock-salt MgxNi(1−x)O solid solution. However, the almost complete segregation of Fe2O3 and Co3O4 oxides played an important role for the high activity of the Fe–Co based catalyst. TEM images illustrate that the accumulated carbon over all catalysts are multi-walled carbon nanotubes in nature. The TG data showed that a higher yield of MWCNTs was achieved over bimetallic Fe–Co catalyst compared to the Ni–Fe or Ni–Co containing catalysts

  9. Application of solid-phase heterogeneous catalytic hydrogenation for preparation of ethanolamine labelled by tritium and ethanolamides of aroachidonic, eicosanepentaenic, docosahexaenic acids labelled by tritium partially

    International Nuclear Information System (INIS)

    Ethanolamine labelled with tritium with 35-40 Ci/mmol molar radioactivity is produced from glycolic acid nitrile by means of solid-phase heterogeneous catalytic hydrogenation on 5% Rh/C. Preparational quantities of labelled ethanolamine are produced with 10-20% yield with the use of 5% of pd?C and 70% of glycolic acid aqueous nitrile, the molar activity of the preparation required is 4-6 Ci/mmol. Ethanolamides of arachidonic, eicosapentaenoic, docosahexaenoic acids are synthesized from the labelled ethanolamine. The compound produced are tested by chromatographic and fermentative methods

  10. Catalytic Hydrogenation of the Sweet Principles of Stevia rebaudiana, Rebaudioside B, Rebaudioside C, and Rebaudioside D and Sensory Evaluation of Their Reduced Derivatives

    Directory of Open Access Journals (Sweden)

    Mary Campbell

    2012-11-01

    Full Text Available Catalytic hydrogenation of rebaudioside B, rebaudioside C, and rebaudioside D; the three ent-kaurane diterpene glycosides isolated from Stevia rebaudiana was carried out using Pd(OH2. Reduction of steviol glycosides was performed using straightforward synthetic chemistry with the catalyst Pd(OH2 and structures of the corresponding dihydro derivatives were characterized on the basis of 1D and 2D nuclear magnetic resonance (NMR spectral data indicating that all are novel compounds being reported for the first time. Also, the taste properties of all reduced compounds were evaluated against their corresponding original steviol glycosides and sucrose.

  11. Hydrogen Photogeneration Promoted by Efficient Electron Transfer from Iridium Sensitizers to Colloidal MoS2 Catalysts

    OpenAIRE

    Yong-Jun Yuan; Zhen-Tao Yu; Xiao-Jie Liu; Jian-Guang Cai; Zhong-Jie Guan; Zhi-Gang Zou

    2014-01-01

    We report the utilization of colloidal MoS2 nanoparticles (NPs) for multicomponent photocatalytic water reduction systems in cooperation with a series of cyclometalated Ir(III) sensitizers. The effects of the particle size and particle dispersion of MoS2 NPs catalyst, reaction solvent and the concentration of the components on hydrogen evolution efficiency were investigated. The MoS2 NPs exhibited higher catalytic performance than did other commonly used water reduction catalysts under identi...

  12. Microscopic models for proton transfer in water and strongly hydrogen-bonded complexes with a single-well proton potential

    DEFF Research Database (Denmark)

    Kuznetsov, A.M.; Ulstrup, Jens

    2004-01-01

    A new mechanism and formalism for proton transfer in donor-acceptor complexes with long hydrogen bonds introduced recently [1], is applied to a proton transfer in liquid water. "Structural diffusion" of hydroxonium ions is regarded as totally adiabatic process, with synchronous hindered translati...

  13. Catalytic mechanisms of direct pyrrole synthesis via dehydrogenative coupling mediated by PNP-Ir or PNN-Ru pincer complexes: Crucial role of proton-transfer shuttles in the PNP-Ir system

    KAUST Repository

    Qu, Shuanglin

    2014-04-02

    Kempe et al. and Milstein et al. have recently advanced the dehydrogenative coupling methodology to synthesize pyrroles from secondary alcohols (e.g., 3) and β-amino alcohols (e.g., 4), using PNP-Ir (1) and PNN-Ru (2) pincer complexes, respectively. We herein present a DFT study to characterize the catalytic mechanism of these reactions. After precatalyst activation to give active 1A/2A, the transformation proceeds via four stages: 1A/2A-catalyzed alcohol (3) dehydrogenation to give ketone (11), base-facilitated C-N coupling of 11 and 4 to form an imine-alcohol intermediate (18), base-promoted cyclization of 18, and catalyst regeneration via H2 release from 1R/2R. For alcohol dehydrogenations, the bifunctional double hydrogen-transfer pathway is more favorable than that via β-hydride elimination. Generally, proton-transfer (H-transfer) shuttles facilitate various H-transfer processes in both systems. Notwithstanding, H-transfer shuttles play a much more crucial role in the PNP-Ir system than in the PNN-Ru system. Without H-transfer shuttles, the key barriers up to 45.9 kcal/mol in PNP-Ir system are too high to be accessible, while the corresponding barriers (<32.0 kcal/mol) in PNN-Ru system are not unreachable. Another significant difference between the two systems is that the addition of alcohol to 1A giving an alkoxo complex is endergonic by 8.1 kcal/mol, whereas the addition to 2A is exergonic by 8.9 kcal/mol. The thermodynamic difference could be the main reason for PNP-Ir system requiring lower catalyst loading than the PNN-Ru system. We discuss how the differences are resulted in terms of electronic and geometric structures of the catalysts and how to use the features in catalyst development. © 2014 American Chemical Society.

  14. Intermolecular interactions and proton transfer in the hydrogen halide-superoxide anion complexes.

    Science.gov (United States)

    Lee, Sebastian J R; Mullinax, J Wayne; Schaefer, Henry F

    2016-02-17

    The superoxide radical anion O2(-) is involved in many important chemical processes spanning different scientific disciplines (e.g., environmental and biological sciences). Characterizing its interaction with various substrates to help elucidate its rich chemistry may have far reaching implications. Herein, we investigate the interaction between O2(-) (X[combining tilde] (2)Πg) and the hydrogen halides (X[combining tilde] (1)Σ) with coupled-cluster theory. In contrast to the short (1.324 Å) hydrogen bond formed between the HF and O2(-) monomers, a barrierless proton transfer occurs for the heavier hydrogen halides with the resulting complexes characterized as long (>1.89 Å) hydrogen bonds between halide anions and the HO2 radical. The dissociation energy with harmonic zero-point vibrational energy (ZPVE) for FHO2(-) (X[combining tilde] (2)A'') → HF (X[combining tilde] (1)Σ) + O2(-) (X[combining tilde] (2)Πg) is 31.2 kcal mol(-1). The other dissociation energies with ZPVE for X(-)HO2 (X[combining tilde] (2)A'') → X(-) (X[combining tilde] (1)Σ) + HO2 (X[combining tilde] (2)A'') are 25.7 kcal mol(-1) for X = Cl, 21.9 kcal mol(-1) for X = Br, and 17.9 kcal mol(-1) for X = I. Additionally, the heavier hydrogen halides can form weak halogen bonds H-XO2(-) (X[combining tilde] (2)A'') with interaction energies including ZPVE of -2.3 kcal mol(-1) for HCl, -8.3 kcal mol(-1) for HBr, and -16.7 kcal mol(-1) for HI. PMID:26852733

  15. A ruthenium-grafted triazine functionalized mesoporous polymer: a highly efficient and multifunctional catalyst for transfer hydrogenation and the Suzuki-Miyaura cross-coupling reactions.

    Science.gov (United States)

    Salam, Noor; Kundu, Sudipta K; Roy, Anupam Singha; Mondal, Paramita; Ghosh, Kajari; Bhaumik, Asim; Islam, S M

    2014-05-21

    A new ruthenium-grafted mesoporous organic polymer Ru-MPTAT-1 has been synthesized via simple and facile in situ radical polymerization of 2,4,6-triallyloxy-1,3,5-triazine (TAT) in aqueous medium in the presence of an anionic surfactant (sodium dodecyl sulfate) as a template, followed by grafting of Ru(II) onto its surface. Ru-MPTAT-1 has been characterized by elemental analysis, powder XRD, HRTEM, FT-IR, UV-vis DRS, TG-DTA, FESEM and XPS characterization tools. The Ru-MPTAT-1 material showed very good catalytic activity in the Suzuki-Miyaura cross-coupling reaction for aryl halides and transfer hydrogenation reaction for a series of carbonyl compounds. The catalyst is easily recoverable from the reaction mixture and can be reused several times without appreciable loss of catalytic activity in the above reactions. Highly dispersed and strongly bound Ru(II) sites at the mesoporous polymer surface could be responsible for the observed high activity of the Ru-MPTAT-1 catalyst in these reactions. PMID:24667768

  16. Photo-stability of a-Si solar cells fabricated by “Liquid-Si printing method” and treated with catalytic generated atomic hydrogen

    Energy Technology Data Exchange (ETDEWEB)

    Murayama, Hiroko, E-mail: murayama.hiroko5@jp.panasonic.com [Device Solutions Center, Panasonic Corporation, 3-1-1 Yagumo-naka-machi, Moriguchi City, Osaka 570-8501 (Japan); Ohyama, Tatsushi; Yoshida, Isao; Terakawa, Akira [Device Solutions Center, Panasonic Corporation, 3-1-1 Yagumo-naka-machi, Moriguchi City, Osaka 570-8501 (Japan); Masuda, Takashi [Japan Advanced Institute of Science and Technology, 1-1 Asahidai, Nomi City, Ishikawa 923-1292 (Japan); JST-ERATO Shimoda Nano-Liquid Process Project, 1-1 Asahidai, Nomi City, Ishikawa 923-1292 (Japan); Ohdaira, Keisuke [Japan Advanced Institute of Science and Technology, 1-1 Asahidai, Nomi City, Ishikawa 923-1292 (Japan); Shimoda, Tatsuya [Japan Advanced Institute of Science and Technology, 1-1 Asahidai, Nomi City, Ishikawa 923-1292 (Japan); JST-ERATO Shimoda Nano-Liquid Process Project, 1-1 Asahidai, Nomi City, Ishikawa 923-1292 (Japan)

    2015-01-30

    The film properties and solar cell performances of hydrogenated amorphous silicon (a-Si:H) fabricated by a newly developed non-vacuum process “Liquid-Si printing method” were systematically investigated by comparing to the conventional plasma-chemical vapor deposition method. The as-printed a-Si:H films showed relatively high Urbach-tail characteristic energy (E{sub ch}), high [Si–H{sub 2}]/[Si–H], and low photoconductivity (~ 10{sup −7} S/cm). However, the [Si–H{sub 2}]/[Si–H] decreased, and the photoconductivity was improved to the device grade level (~ 10{sup −5} S/cm) after appropriate catalytic-generated atomic hydrogen treatment. It was also found that the light-induced degradation of the photoconductivity and solar cell efficiency of the printed samples were less than half of the conventional a-Si:H case.

  17. Photo-stability of a-Si solar cells fabricated by “Liquid-Si printing method” and treated with catalytic generated atomic hydrogen

    International Nuclear Information System (INIS)

    The film properties and solar cell performances of hydrogenated amorphous silicon (a-Si:H) fabricated by a newly developed non-vacuum process “Liquid-Si printing method” were systematically investigated by comparing to the conventional plasma-chemical vapor deposition method. The as-printed a-Si:H films showed relatively high Urbach-tail characteristic energy (Ech), high [Si–H2]/[Si–H], and low photoconductivity (~ 10−7 S/cm). However, the [Si–H2]/[Si–H] decreased, and the photoconductivity was improved to the device grade level (~ 10−5 S/cm) after appropriate catalytic-generated atomic hydrogen treatment. It was also found that the light-induced degradation of the photoconductivity and solar cell efficiency of the printed samples were less than half of the conventional a-Si:H case

  18. High Surface Area Tungsten Carbides: Synthesis, Characterization and Catalytic Activity towards the Hydrogen Evolution Reaction in Phosphoric Acid at Elevated Temperatures

    DEFF Research Database (Denmark)

    Tomás García, Antonio Luis; Li, Qingfeng; Jensen, Jens Oluf;

    2014-01-01

    nitride route and with carbon black as template, the obtained tungsten carbide samples had higher BET area. In 100% H3PO4 at temperatures up to 185°C, the carbide powders showed superior activity towards the hydrogen evolution reaction. A deviation was found in the correlation between the BET area and...... catalytic activity; this was attributed to the presence of excess amorphous carbon in the carbide powder. TEM imaging and TGA-DTA results revealed a better correlation of the activity with the carbide particle size.......Tungsten carbide powders were synthesized as a potential electrocatalyst for the hydrogen evolution reaction in phosphoric acid at elevated temperatures. With ammonium metatungstate as the precursor, two synthetic routes with and without carbon templates were investigated. Through the intermediate...

  19. Catalytic steam gasification of biomass in fluidized bed at low temperature: Conversion from livestock manure compost to hydrogen-rich syngas

    International Nuclear Information System (INIS)

    Utilizing large amounts of animal waste as a source of renewable energy has the potential to reduce its disposal problems and associated pollution issues. Gasification characteristics of the manure compost make it possible for low temperature gasification. In this paper, an energy efficient approach to hydrogen-rich syngas from manure compost is represented at relatively low temperature, around 600 oC, in a continuous-feeding fluidized bed reactor. The effects of catalyst performance, reactor temperature, steam, and reaction type on gas yield, gas composition, and carbon conversion efficiency are discussed. The Ni-Al2O3 catalyst simultaneously promotes tar cracking and steam reforming. Higher temperature contributes to higher gas yield and carbon conversion. The steam introduction increases hydrogen yield, by steam reforming and water-gas shift reaction. Two-stage gasification is also tried, showing the advantage of better catalyst utilization and enhancing the catalytic reactions to some extent.

  20. Simulation of heat and mass transfer in activated carbon tank for hydrogen storage

    Energy Technology Data Exchange (ETDEWEB)

    Xiao, Jinsheng [School of Automotive Engineering, Wuhan University of Technology, Hubei 430070 (China); State Key Laboratory of Advanced Technology for Materials Synthesis and Progressing, Wuhan University of Technology, Hubei 430070 (China); Hydrogen Research Institute, Universite du Quebec a Trois-Rivieres, Trois-Rivieres, QC G9A 5H7 (Canada); Tong, Liang [School of Automotive Engineering, Wuhan University of Technology, Hubei 430070 (China); Department of Mechanical and Automotive Engineering, Huaxia College, Wuhan University of Technology, Hubei 430070 (China); Deng, Caihua [School of Automotive Engineering, Wuhan University of Technology, Hubei 430070 (China); Benard, Pierre; Chahine, Richard [Hydrogen Research Institute, Universite du Quebec a Trois-Rivieres, Trois-Rivieres, QC G9A 5H7 (Canada)

    2010-08-15

    The charging process of hydrogen storage tank based on bed of activated carbon in a steel container at room temperature (295 K) and medium storage pressure (10 MPa) is simulated with an axisymmetric geometry model using the finite volume commercial solver Fluent. The mass flux profile at the entrance is established using user-defined functions (UDFs). The heat and mass transfer processes in the cylindrical steel tank packed with activated carbon are discussed considering the influence of viscous resistance and inertial resistance of the porous media. The velocity distribution and its effect on the temperature distribution are analyzed. The effects of the flow rate at the inlet and of the adsorption factor on the charging process are studied. A computational fluid dynamics (CFD) approach based on finite volume simulations is used. Results show that the temperature near the bottom of the tank is higher than that at the entrance, temperature in the center of the tank is higher than that near the wall and rises somewhat faster along the axial compared to the radial direction. The highest hydrogen absolute adsorption occurs at the entrance of the tank. A good agreement is found between the simulation results and the available experimental data. The maximum magnitude of the axial velocity is much higher than that of the radial component, resulting in more heat energy transfer along the axial direction than radial direction. In addition, the pressure reaches equilibrium earlier when the mass flow is higher, and the temperature reaches a maximum value faster. (author)

  1. Numerical investigation of coupled heat and mass transfer during desorption of hydrogen in metal hydride beds

    Energy Technology Data Exchange (ETDEWEB)

    Muthukumar, P.; Satheesh, A.; Madhavakrishna, U.; Dewan, Anupam [Department of Mechanical Engineering, Indian Institute of Technology Guwahati, Guwahati 781039, Assam (India)

    2009-01-15

    This paper presents a numerical investigation of two-dimensional coupled heat and mass transfer processes in MmNi{sub 4.6}Fe{sub 0.4} and MmNi{sub 4.6}Al{sub 0.4} based metal hydride beds of cylindrical configuration during desorption of hydrogen using a commercial software FLUENT 6.1.22. Temperature and concentration profiles at different radial locations, variation of average bed temperature and amount of hydrogen desorbed are presented at different hot fluid temperatures and bed thicknesses ranging from 30 to 50 C and 5 to 15 mm, respectively. The numerical results show that the dehydriding process for both the alloys depends on the temperature distribution in the metal hydride bed. At a given hot fluid temperature of 50 C, MmNi{sub 4.6}Fe{sub 0.4} and MmNi{sub 4.6}Al{sub 0.4} desorb the maximum hydrogen of about 1.11 and 1.28 wt%, respectively at the supply conditions of 30 bar and 25 C. The present computational results are also compared with the experimental data reported in the literature and a good agreement was found between the two. (author)

  2. Research Progress in Catalytic Hydrogenation of CO2 to Ethanol%CO2催化加氢制乙醇研究进展

    Institute of Scientific and Technical Information of China (English)

    王慧敏; 杨绪壮; 张兵兵; 苏海全

    2012-01-01

    燃料乙醇是可再生的清洁燃料,具有替代汽油的应用前景.以CO2气体为碳源并通过催化加氢制燃料乙醇具有环境保护和节约能源的现实意义.主要介绍了CO2催化加氢的反应机理以及催化剂活性组分、前驱物、助剂及载体对催化活性、产物选择性的影响,同时介绍了反应条件对催化过程的影响.%Fuel ethanol is often regarded as a potential renewable clean alternative fuel to gasoline. It has practical significance of environmental protection and energy conservation to synthesize fuel ethanol by the hydrogenation of CO2. The reaction mechanism of catalytic hydrogenation of CO2 to ethanol as well as the effects of active sites,precursors,promoters and supports on the catalytic activity and product selectivity are reviewed. Moreover,the effects of reaction conditions on the catalysis are also introduced.

  3. 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

  4. 对苯二甲酸催化加氢的Ru-Sn-B/丝光沸石催化性能%Catalytic performance of Ru-Sn-B/mordenite for terephthalic acid catalytic hydrogenation

    Institute of Scientific and Technical Information of China (English)

    赵葛新; 靳海波; 何广湘; 郭志武; 杨索和

    2012-01-01

    采用分步浸渍和化学还原的方法制备以丝光沸石分子筛为载体的Ru-Sn-B催化剂,研究了在负载型催化剂Ru-Sn-B/丝光沸石上对苯二甲酸催化加氢制备1,4-环己烷二甲醇的加氢催化性能,并利用XRD和BET等分析手段对Ru-Sn-B/丝光沸石催化剂进行表征.结果 表明,RuB和Sn在丝光沸石上具有较好的分散性,Ru-Sn-B/丝光沸石催化剂具有较高的催化活性和选择性;催化加氢过程中采用两段升温升压的方法,对苯二甲酸转化率约100%,产物1,4-环己烷二甲醇的收率为73.5%,反式与顺式之比为2.42.%Ru-Sn-B/mordenite catalysts were prepared by sequential impregnation and chemical reduction methods and using mordenite zeolite as the carrier. The catalytic performance of Ru-Sn-B/mordenite catalysts for terephthalic acid hydrogenation to 1,4-cyclohexanedimethanol was investigated. The as-prepared catalysts were characterized by XRD, BET, EDS and ICP. The results showed that RuB and Sn had better dispersion on the mordenite, and Ru-Sn-B/mordenite catalyst possessed high catalytic activity and selectivity. The catalytic hydrogenation process used two stage enhancement method of temperature and pressure. Terephthalic acid conversion rate of about 100% ,the yield of the product 1,4-cyclohexanedimethanol of 73.5% ,and the ratio of trans and cis of the product of 2.42 were attained,respectively.

  5. ONO-pincer ruthenium complex-bound norvaline for efficient catalytic oxidation of methoxybenzenes with hydrogen peroxide.

    Science.gov (United States)

    Yoshida, Ryota; Isozaki, Katsuhiro; Yokoi, Tomoya; Yasuda, Nobuhiro; Sadakane, Koichiro; Iwamoto, Takahiro; Takaya, Hikaru; Nakamura, Masaharu

    2016-08-21

    The enhanced catalytic activity of ruthenium complex-bound norvaline Boc-l-[Ru]Nva-OMe 1, in which the ONO-pincer ruthenium complex Ru(pydc)(terpy) 2 is tethered to the α-side chain of norvaline, has been demonstrated for the oxidation of methoxybenzenes to p-benzoquinones with a wide scope of substrates and unique chemoselectivity. PMID:27314504

  6. Theoretical and computational study of the energy dependence of the muon transfer rate from hydrogen to higher-Z gases

    Energy Technology Data Exchange (ETDEWEB)

    Bakalov, Dimitar, E-mail: dbakalov@inrne.bas.bg [Institute for Nuclear Research and Nuclear Energy, Bulgarian Academy of Sciences, Tsarigradsko chaussée 72, Sofia 1784 (Bulgaria); Adamczak, Andrzej [Institute of Nuclear Physics, Polish Academy of Sciences, ul. Radzikowskiego 152, 31-342 Krakow (Poland); Stoilov, Mihail [Institute for Nuclear Research and Nuclear Energy, Bulgarian Academy of Sciences, Tsarigradsko chaussée 72, Sofia 1784 (Bulgaria); Vacchi, Andrea [Istituto Nazionale di Fisica Nucleare, Sezione di Trieste, Via A. Valerio 2, 34127 Trieste (Italy)

    2015-01-23

    The recent PSI Lamb shift experiment and the controversy about proton size revived the interest in measuring the hyperfine splitting in muonic hydrogen as an alternative possibility for comparing ordinary and muonic hydrogen spectroscopy data on proton electromagnetic structure. This measurement critically depends on the energy dependence of the muon transfer rate to heavier gases in the epithermal range. The available data provide only qualitative information, and the theoretical predictions have not been verified. We propose a new method by measurements of the transfer rate in thermalized target at different temperatures, estimate its accuracy and investigate the optimal experimental conditions. - Highlights: • Method for measuring the energy dependence of muon transfer rate to higher-Z gases. • Thermalization and depolarization of muonic hydrogen studied by Monte Carlo method. • Optimal experimental conditions determined by Monte Carlo simulations. • Mathematical model and for estimating the uncertainty of the experimental results.

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

    Directory of Open Access Journals (Sweden)

    Rodiansono Rodiansono

    2015-07-01

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

  8. Enhancement of hydrogen production by secondary metal oxide dopants on NiO/CaO material for catalytic gasification of empty palm fruit bunches

    International Nuclear Information System (INIS)

    The increase of fossil fuel burning to meet massive energy demands has resulted in major environmental problems. Extensive green house gas emissions and the depletion of non-renewable resources have promoted the use of hydrogen as an alternative energy source. Empty palm fruit bunches (EFB) are a type of agricultural waste that have a high potential for use as a sustainable biomass feedstock for hydrogen production. This study is focused on generation of biomass-derived hydrogen through catalytic biomass gasification using a modified CaO-based catalyst. The catalyst was prepared by adding 5% Ni as a primary dopant, followed by the addition of secondary dopants (La, K, Co, Fe) through a wet impregnation method, and characterised by X-ray diffractometer (XRD), N2 adsorption (BET) and Thermogravimetric Analysis (TGA). The synthesised catalysts were used as the primary catalysts in the reaction and were tested in temperature programmed gasification (TPG). The reaction was carried out in a partial oxygen environment by incorporating the biomass with the catalyst in a ratio of 1:2 from 50 to 900 °C and the product gases were detected by an online mass spectrometer. Interestingly, the addition of secondary dopants significantly increased the hydrogen production with notable changes in the CO2 absorption capacity of the catalyst. Moreover, K, Co and Fe dopants showed tar reforming properties and the highest hydrogen yield was observed with K as the added catalyst. -- Highlights: ► Describe about CaO modification with primary and secondary dopants. ► Discuss the effect of secondary dopants on Tar cracking and CO2 absorption of the CaO catalyst. ► Identified the dopants that promote tar cracking and reforming reaction favour to H2 production.

  9. Hydrogen and methoxy coadsorption in the computation of the catalytic conversion of methanol on the ceria (111) surface

    Science.gov (United States)

    Beste, Ariana; Overbury, Steven H.

    2016-06-01

    Methanol decomposition to formaldehyde catalyzed by the ceria (111) surface was investigated using the DFT + U method. Our results rationalize experimental temperature programmed desorption experiments on the fully oxidized surface. Particular attention was paid to the effect of coadsorption of methoxy and hydrogen on various aspects of the conversion process. This issue had been raised by the experimental observation of water desorption at low temperature removing hydrogen from the system. Within this context, we also investigated hydrogen diffusion on the ceria surface. The hydrogen/methoxy interaction on ceria was shown to be ionic regardless of separation distance. The barrier for dehydrogenation of methoxy using the ionic model system, where hydrogen is coadsorbed, is above 1 eV. This barrier becomes negligible if an incorrect neutral model without coadsorbed hydrogen is employed. While water formation from isolated surface hydrogen is unlikely at low temperature, the presence of coadsorbed methoxy reduces the reaction energy for water formation considerably. For the dehydrated surface, we observed that the preference of the electron to locate at the methoxy oxygen instead of the cerium atom results in a surface that does not contain Ce3 + ions, despite the existence of a vacancy.

  10. Study of coupled heat and mass transfer during absorption of hydrogen in MmNi4·6Al0·4 based hydrogen storage device

    Indian Academy of Sciences (India)

    P Muthukumar; Manvendra M Umekar

    2009-04-01

    A two-dimensional numerical analysis of coupled heat and mass transfer processes in a cylindrical metal hydride reactor containing MmNi4·6Al0·4 is presented. To understand the hydrogen absorption mechanism the governing equations for energy, momentum and mass conservation and reaction kinetic equations are solved simultaneously using the finite volume method (FVM). Performance studies on MmNi4·6Al0·4 based hydrogen storage device are carried out by varying the hydrogen supply pressure, absorption (cooling fluid) temperature, overall heat transfer coefficient and hydride bed thickness. Effect of convection terms in the energy equation on hydrogen storage performance is found to be negligible. The results obtained from the computer simulation showed good agreement with the available experimental data. At the supply conditions of 30 bar and 298 K, MmNi4·6Al0·4 stores about 1·28 wt%, which is very close to the experimental value of 1·3 wt%. Overall high heat transfer coefficients are found to reduce the absorption time significantly.

  11. On the transferability of atomic contributions to the optical rotatory power of hydrogen peroxide, methyl hydroperoxide and dimethyl peroxide

    DEFF Research Database (Denmark)

    Sánchez, Marina; Alkorta, Ibon; Elguero, José;

    2014-01-01

    partitioned into atomic and group contributions. In the present work, we investigate the transferability of such individual contributions in a series of small, chiral molecules: hydrogen peroxide, methyl hydroperoxide and dimethyl peroxide. The isotropic atomic or group contributions have been evaluated for...... the hydrogen, oxygen and carbon atoms as well as for the methyl group at the level of time-dependent density functional theory with the B3LYP exchange-correlation functional employing a large Gaussian basis set. We find that the atomic or group contributions are not transferable among these three...

  12. Hydrogenation of nitriles on a well-characterized nickel surface: From surface science studies to liquid phase catalytic activity measurements

    Energy Technology Data Exchange (ETDEWEB)

    Gardin, D.E.

    1993-12-01

    Nitrile hydrogenation is the most commonly used method for preparing diverse amines. This thesis is aimed at the mechanism and factors affecting the performance of Ni-based catalysts in nitrile hydrogenations. Surface science techniques are used to study bonding of nitriles and amines to a Ni(111) surface and to identify surface intermediates. Liquid-phase hydrogenations of cyclohexene and 1-hexene on a Pt foil were carried out successfully. Finally, knowledge about the surface structure, surface chemical bond, dynamics of surface atoms (diffusion, growth), and reactivity of metal surfaces from solid-gas interface studies, is discussed.

  13. An efficient route for catalytic activity promotion via hybrid electro-depositional modification on commercial nickel foam for hydrogen evolution reaction in alkaline water electrolysis

    International Nuclear Information System (INIS)

    Highlights: • Mono-Cu surface modification depress the HER activity of Ni-foam. • Hybrid Ni-foam/Cu0.01/Co0.05 exhibits superior HER performance. • Layer-by-layer structure may contribute to a synergistic promoting effect. - Abstract: In this paper, the single- and hybrid-layered Cu, Ni and Co thin films were electrochemically deposited onto the three-dimensional nickel foam as composite cathode catalyst for hydrogen evolution reaction in alkaline water electrolysis. The morphology, structure and chemical composition of the electrodeposited composite catalysts were investigated using X-ray diffraction (XRD), scanning electron microscopy (SEM) and energy dispersive X-ray analysis (EDX). Electrochemical measurement depicted that, for the case of the monometallic layered samples, the general activity for hydrogen evolution reaction followed the sequence: Ni-foam/Ni > Ni-foam/Co > bare Ni-foam > Ni-foam/Cu. It is noteworthy that, the hybrid-layered Ni-foam/Cu0.01/Co0.05 exhibited the highest catalytic activity towards hydrogen evolution reaction with the current density as high as 2.82 times that of the bare Ni-foam. Moreover, both excellent electrochemical and physical stabilities can also be acquired on the Ni-foam/Cu0.01/Co0.05, making this hybrid-layered composite structure as a promising HER electro-catalyst

  14. On the role of metal particle size and surface coverage for photo-catalytic hydrogen production; a case study of the Au/CdS system

    KAUST Repository

    Majeed, I.

    2015-09-25

    Photo-catalytic hydrogen production has been studied on Au supported CdS catalysts under visible light irradiation in order to understand the effect of Au particle size as well as the reaction medium properties. Au nanoparticles of size about 2-5 nm were deposited over hexagonal CdS particles using a new simple method involving reduction of Au3+ ions with iodide ions. Within the investigated range of Au (between 1 and 5 wt. %) fresh particles with mean size of 4 nm and XPS Au4f/Cd3d surface ratio of 0.07 showed the highest performance (ca. 1 molecule of H2 / Auatom s−1) under visible light irradiation (>420 nm and a flux of 35 mW/cm2). The highest hydrogen production rate was obtained from water (92%)-ethanol (8%) in an electrolyte medium (Na2S-Na2SO3). TEM studies of fresh and used catalysts showed that Au particle size increases (almost 5 fold) with increasing photo-irradiation time due to photo-agglomeration effect yet no sign of deactivation was observed. A mechanism for hydrogen production from ethanol-water electrolyte mixture is presented and discussed.

  15. Effects of hydrogen bonds in association with flavin and substrate in flavoenzyme d-amino acid oxidase. The catalytic and structural roles of Gly313 and Thr317.

    Science.gov (United States)

    Setoyama, Chiaki; Nishina, Yasuzo; Tamaoki, Haruhiko; Mizutani, Hisashi; Miyahara, Ikuko; Hirotsu, Ken; Shiga, Kiyoshi; Miura, Retsu

    2002-01-01

    According to the three-dimensional structure of a porcine kidney D-amino acid oxidase-substrate (D-leucine) complex model, the G313 backbone carbonyl recognizes the substrate amino group by hydrogen bonding and the side-chain hydroxyl of T317 forms a hydrogen bond with C(2)=O of the flavin moiety of FAD [Miura et al. (1997) J. Biochem. 122, 825-833]. We have designed and expressed the G313A and T317A mutants and compared their enzymatic and spectroscopic properties with those of the wild type. The G313A mutant shows decreased activities to various D-amino acids, but the pattern of substrate specificity is different from that of the wild type. The results imply that the hydrogen bond between the G313 backbone carbonyl and the substrate amino group plays important roles in substrate recognition and in defining the substrate specificity of D-amino acid oxidase. The T317A mutant shows a decreased affinity for FAD. The steady-state kinetic measurements indicate diminished activities of T317A to substrate D-amino acids. The transient kinetic parameters measured by stopped-flow spectroscopy revealed that T317 plays key roles in stabilizing the purple intermediate, a requisite intermediate in the oxidative half-reaction, and in enhancing the release of the product from the active site, thereby optimizing the overall catalytic process of D-amino acid oxidase. PMID:11754736

  16. Aqueous-phase catalytic hydrogenation of furfural to cyclopentanol over Cu-Mg-Al hydrotalcites derived catalysts:Model reaction for upgrading of bio-oil

    Institute of Scientific and Technical Information of China (English)

    Minghao; Zhou; Zuo; Zeng; Hongyan; Zhu; Guomin; Xiao; Rui; Xiao

    2014-01-01

    A series of Cu-Mg-Al hydrotalcites derived oxides with a(Cu+Mg)/Al mole ratio of 3 and varied Cu/Mg mole ratio(from 0.07 to 0.30) were prepared by co-precipitation and calcination methods, then they were introduced to the hydrogenation of furfural in aqueous-phase. Effects of Cu/Mg mole ratio, reaction temperature, initial hydrogen pressure, reaction time and catalyst amount on the conversion rate of furfural as well as the selectivity toward desired product cyclopentanol were systematically investigated. The conversion of furfural over calcined hydrotalcite catalyst with a Cu/Mg mole ratio of 0.2 was up to 98.5% when the reaction was carried out under 140 ?C and the initial hydrogen pressure of 4 MPa for 10 h, while the selectivity toward cyclopentanol was up to 94.8%. The catalysts were characterized by XRD and SEM. XRD diffraction of all the samples showed characteristic pattern of hydrotalcite with varied peak intensity as a result of different Cu content. The catalytic activity was improved gradually with the increase of Cu component in the hydrotalcite.

  17. Heat transfer and chemical kinetics in the exhaust system of a cold-start engine fitted with a three-way catalytic converter

    Energy Technology Data Exchange (ETDEWEB)

    Chan, S.H.; Hoang, D.L. [Nanyang Technological Univ., School of Mechanical and Production Engineering, Nanyang (Singapore); Zhou, P.L. [Newcastle upon Tyne Univ., Dept. of Marine Technology, Newcastle upon Tyne (United Kingdom)

    2000-10-01

    Modelling of cold-start engine exhaust behaviour is a difficult task as it involves complicated heat transfer processes associated with water condensation and evaporation at the walls of the exhaust manifold/pipe and monolith cells, and the chemical reactions of CO/HC/NO in the three-way catalytic converter. This paper presents a model that is capable of predicting the exhaust gas temperatures along the exhaust system and across the catalyst monolith, both spatially and temporally, from the moment when the engine is cranked. The conversions of CO/HC/NO to harmless carbon dioxide, water and nitrogen at the catalytic converter downstream have been validated satisfactorily by the experimental data. The distortion of measured NO emission data/signals due to the dynamic behaviour of the chemiluminescence analyser has been reconstructed by means of a signal inference technique before these signals were used to validate the predictive capability of the model developed. (Author)

  18. Through-bond photoinduced electron transfer in a porphyrin-fullerene conjugate held by a Hamilton type hydrogen bonding motif.

    Science.gov (United States)

    D'Souza, Francis; Venukadasula, Ganesh M; Yamanaka, Ken-ichi; Subbaiyan, Navaneetha K; Zandler, Melvin E; Ito, Osamu

    2009-03-21

    Control over the occurrence of through-bond electron transfer in self-assembled donor-acceptor conjugates is often difficult, since through-space electron transfer also competes due to the flexible nature of the spacer used to link the entities. In the present study, we have constructed a self-assembled donor-acceptor conjugate held solely by complementary hydrogen bonding and established through-bond electron transfer. The protocol used here is a Hamilton type hydrogen bonding motif involving self-assembly of a carboxylic acid functionalized porphyrin and 2-aminopyridine functionalized fullerene. Owing to the presence of two-point hydrogen bonds, the structure of the dyad is free from rotation with a donor-acceptor distance positioned appropriately to justify the through-bond electron transfer. Detailed spectral, computational and photochemical studies reveal efficient photoinduced charge separation and slow charge recombination in the studied conjugate, thus, bringing out the fundamental advantages of the directional hydrogen-bonding in the construction of donor-acceptor conjugates based on biomimetic principles and their functional role in governing electron transfer events. PMID:19262925

  19. About Rotational Transitions and Muon Transfer in Muonic Hydrogen-Helium Systems

    International Nuclear Information System (INIS)

    Rotational J=1→J=0 transitions in muonic molecule, (3Heμd)J++, in [(3Heμd)++,2e]-D and [(3Heμd)++,e]+-D collisions are considered. The corresponding cross sections and reaction rates are calculated in the frame of the semi-classical approximation using He-H(H+) and He+-H(H+) interaction potentials. The results obtained are about two orders of magnitudes smaller than the corresponding quantum-mechanical ones calculated previously by the authors using plane-waves for description of relative motion of the subsystems. Reaction rates for radiative and Auger muon transfer from hydrogen to helium are also calculated semi-classically. The corresponding results are close to the quantum-mechanical ones published elsewhere.

  20. Hydrogen transfer experiments and modelization in clay rocks for radioactive waste deep geological repository

    International Nuclear Information System (INIS)

    Gases will be generated by corrosion of high radioactive waste containers in deep geological repositories. A gas phase will be generated. Gas pressure will build up and penetrated the geological formation. If gases do not penetrate the geological barrier efficiently, the pressure build up may create a risk of fracturing and of creation of preferential pathways for radionuclide migration. The present work focuses on Callovo-Oxfordian argillites characterisation. An experiment, designed to measure very low permeabilities, was used with hydrogen/helium and analysed using the Dusty Gas Model. Argillites close to saturation have an accessible porosity to gas transfer that is lower than 0,1% to 1% of the porosity. Analysis of the Knudsen effect suggests that this accessible network should be made of 50 nm to 200 nm diameter pores. The permeabilities values were integrated to an ANDRA operating model. The model showed that the maximum pressure expected near the repository would be 83 bar. (author)

  1. A HYDROGEN BONDING ASSISTED CATALYST SCREENED OUT VIA COMBINATORIAL CHEMISTRY STRATEGY

    Institute of Scientific and Technical Information of China (English)

    XUMancai; OUZhize; 等

    2000-01-01

    Possibilities for enhancement of catalytic reaction rate by combining phase transfer catalysis and hydrogen bonding of the catalyst with the substrate and reagent were studied.A phase transfer catalyst library with sixty polystyrene-supported quaternary ammonium salt catalysts was synthesized.The reduction of acetophenone by NaBH4 was used as the probing reaction to select out the ost active catalyst in the library by using iterative method.which was the gel-type triethanolamine aminsating strongly asic anion exchange resin with the crosslinking degeree of 2% A hydrogen bonding assisted catalytic mechanism was proposed to explain the high catalytic activity of the catalyst.

  2. Deuterium labeling studies in the transfer hydrogenation of ketones and in the disproportionation of diphenylcarbinol over alumina

    International Nuclear Information System (INIS)

    Paper describes deuterium labeling studies which confirm the direct hydrogen transfer mechanism for the transfer hydrogenation of ketones as well as for the disproportionation and the transfer hydrogenolysis of diphenylcarbinol. Methods for the preparation of diphenylcarbinol-d and 2-propanol-2-d are described. Diphenylmethane-d and diphenylmethane-d2 were prepared as standards for product identification purposes. 2-Propanol-2-d of 92% isotopic purity was used to reduce 4-methyl-2-pentanone and cyclohexanone over 2.2% Na+/Al2O3 at 3000C. Reaction products were 4-methyl-2-pentanol and cyclohexanol. Disproportionation of diphenylcarbinol produced diphenylamine, benzophenone, and water, over pure alumina at 3000C. Reaction products were analyzed by gas chromatography, and pure samples were isolated by preparative gas chromatography. Isotopic purities were estimated by ir, NMR, and mass spectrometry. A somewhat speculative representation of the direct hybrid transfer mechanism is considered

  3. Production of superoxide and hydrogen peroxide in medium used to culture Legionella pneumophila: catalytic decomposition by charcoal.

    OpenAIRE

    Hoffman, P S; Pine, L; Bell, S.

    1983-01-01

    The difficulties associated with the growth of Legionella species in common laboratory media may be due to the sensitivity of these organisms to low levels of hydrogen peroxide and superoxide radicals. Exposure of yeast extract (YE) broth to fluorescent light generated superoxide radicals (3 microM/h) and hydrogen peroxide (16 microM/h). Autoclaved YE medium was more prone to photochemical oxidation than YE medium sterilized by filtration. Activated charcoals and, to a lesser extent, graphite...

  4. Development of the Transferable Potentials for Phase Equilibria Model for Hydrogen Sulfide.

    Science.gov (United States)

    Shah, Mansi S; Tsapatsis, Michael; Siepmann, J Ilja

    2015-06-11

    The transferable potentials for phase equilibria force field is extended to hydrogen sulfide. The pure-component and binary vapor-liquid equilibria with methane and carbon dioxide and the liquid-phase relative permittivity are used for the parametrization of the Lennard-Jones (LJ) and Coulomb interactions, and models with three and four interaction sites are considered. For the three-site models, partial point charges are placed on the sites representing the three atoms, while the negative partial charge is moved to an off-atom site for the four-site models. The effect of molecular shape is probed using either only a single LJ interaction site on the sulfur atom or adding sites also on the hydrogen atoms. This procedure results in four distinct models, but only those with three LJ sites can accurately reproduce all properties considered for the parametrization. These two are further assessed for predictions of the liquid-phase structure, the lattice parameters and relative permittivity for the face-centered-cubic solid, and the triple point. An effective balance between LJ interactions and the dipolar and quadrupolar terms of the first-order electrostatic interactions is struck in order to obtain a four-site model that describes the condensed-phase properties and the phase equilibria with high accuracy. PMID:25981731

  5. Adsorption-parallel catalytic waves of cinnamic acid in hydrogen peroxide-tetra-n-butylammonium bromide-acetate system

    Institute of Scientific and Technical Information of China (English)

    亢晓峰; 过玮; 赵川; 宋俊峰

    2000-01-01

    The mechanism of the adsorption-parallel catalytic wave of cinnamic acid (C6H5—CH = CH—COOH) in acetate buffer (pH = 4.0)-H2O2-tetra-n-butylammonium bromide (Bu4N · Br) solution was studied by the linear-sweep polarography, cyclic voltammetry and digital simulation approach. Experimental results indicate that the reduction mechanism of cinnamic acid is ECdimE’ process, in which the C = C double bond of cinnamic acid first undergoes 1 e, 1H+ reduction to produce an intermediate free radical C6H5—CH—CH2—COOH(E), then the further reduction of the free radical in 1e,1H+ addition (E’) occurs simultaneously with a dimerization reaction between two free radicals (Cdim). Bu4N · Br enhances the polarographic current of cinnamic acid and shifts the peak potential to positive direction. The enhancement action of Bu4N · Br is due to the adsorption of cinnamic acid induced by Bu4N+ species. In addition, H2O2 causes the parallel catalytic wave of cinnamic acid. The mechanism of the catalytic wave is EC’ proce

  6. Increasing Octane Value in Catalytic Cracking of n-Hexadecane with Addition of *BEA Type Zeolite

    OpenAIRE

    Iori Shimada; Ryoichi Imai; Yoshinori Hayasaki; Hiroshi Fukunaga; Nobuhide Takahashi; Toru Takatsuka

    2015-01-01

    In this study, multifunctional catalysts were developed by adding *BEA or MFI zeolite with high Si/Al ratio to a residual fluidized catalytic cracking (RFCC) catalyst and tested in the catalytic cracking of n-hexadecane, which is a heavy crude oil model compound, for the purpose of increasing the octane value of produced gasoline under the strong hydrogen transfer activity of the RFCC catalyst. Reaction products analysis revealed that the addition of *BEA zeolite to the RFCC catalyst increase...

  7. Shape-dependent electron transfer kinetics and catalytic activity of NiO nanoparticles immobilized onto DNA modified electrode: fabrication of highly sensitive enzymeless glucose sensor.

    Science.gov (United States)

    Sharifi, Ensiyeh; Salimi, Abdollah; Shams, Esmaeil; Noorbakhsh, Abdollah; Amini, Mohammad K

    2014-06-15

    Herein we describe improved electron transfer properties and catalytic activity of nickel oxide nanoparticles (NiONPs) via the electrochemical deposition on DNA modified glassy carbon electrode (DNA/GCE) surface. NiONPs deposited on the bare and DNA-coated GCE showed different morphologies, electrochemical kinetics and catalytic activities. The atomic force microscopy (AFM) images revealed the formation of triangular NPs on the DNA/GCE that followed the shape produced by the DNA template, while the electrodeposition of NiONPs on the bare GCE surface led to the formation of spherical nanoparticles. Electrochemical impedance spectroscopy (EIS) measurements revealed lower charge-transfer resistance (Rct) of triangular NiONPs compared to spherical NPs. Furthermore, the electrocatalytic activity of triangular NiONPs compared to spherical NPs toward glucose oxidation in alkaline media was significantly improved. The amperometric oxidation of glucose at NiONP-DNA/GCE, yielded a very high sensitivity of 17.32 mA mM(-1)cm(-2) and an unprecedented detection limit of 17 nM. The enhanced electron transfer properties and electrocatalytic activity of NiONP-DNA/GCE can be attributed to the higher fraction of sharp corners and edges present in the triangular NiONPs compared to the spherical NPs. The developed sensor was successfully applied to the determination of glucose in serum samples. PMID:24525015

  8. Mesoporous carbon-supported Pd nanoparticles with high specific surface area for cyclohexene hydrogenation: Outstanding catalytic activity of NaOH-treated catalysts

    Science.gov (United States)

    Puskás, R.; Varga, T.; Grósz, A.; Sápi, A.; Oszkó, A.; Kukovecz, Á.; Kónya, Z.

    2016-06-01

    Extremely high specific surface area mesoporous carbon-supported Pd nanoparticle catalysts were prepared with both impregnation and polyol-based sol methods. The silica template used for the synthesis of mesoporous carbon was removed by both NaOH and HF etching. Pd/mesoporous carbon catalysts synthesized with the impregnation method has as high specific surface area as 2250 m2/g. In case of NaOH-etched impregnated samples, the turnover frequency of cyclohexene hydrogenation to cyclohexane at 313 K was obtained ~ 14 molecules • site- 1 • s- 1. The specific surface area of HF-etched samples was higher compared to NaOH-etched samples. However, catalytic activity was ~ 3-6 times higher on NaOH-etched samples compared to HF-etched samples, which can be attributed to the presence of sodium and surface hydroxylgroups of the catalysts etched with NaOH solution.

  9. Effect of Copper Nanoparticles Dispersion on Catalytic Performance of Cu/SiO2 Catalyst for Hydrogenation of Dimethyl Oxalate to Ethylene Glycol

    International Nuclear Information System (INIS)

    Cu/SiO2 catalysts, for the synthesis of ethylene glycol (EG) from hydrogenation of dimethyl oxalate (DMO), were prepared by ammonia-evaporation and sol-gel methods, respectively. The structure, size of copper nanoparticles, copper dispersion, and the surface chemical states were investigated by X-ray diffraction (XRD), transmission electron microscopy (TEM), temperature-programmed reduction (TPR), and X-ray photoelectron spectroscopy (XPS) and N2 adsorption. It is found the structures and catalytic performances of the catalysts were highly affected by the preparation method. The catalyst prepared by sol-gel method had smaller average size of copper nanoparticles (about 3-4 nm), better copper dispersion, higher Cu+/C0 ratio and larger BET surface area, and higher DMO conversion and EG selectivity under the optimized reaction conditions.

  10. Effect of Copper Nanoparticles Dispersion on Catalytic Performance of Cu/SiO2 Catalyst for Hydrogenation of Dimethyl Oxalate to Ethylene Glycol

    Directory of Open Access Journals (Sweden)

    Yajing Zhang

    2013-01-01

    Full Text Available Cu/SiO2 catalysts, for the synthesis of ethylene glycol (EG from hydrogenation of dimethyl oxalate (DMO, were prepared by ammonia-evaporation and sol-gel methods, respectively. The structure, size of copper nanoparticles, copper dispersion, and the surface chemical states were investigated by X-ray diffraction (XRD, transmission electron microscopy (TEM, temperature-programmed reduction (TPR, and X-ray photoelectron spectroscopy (XPS and N2 adsorption. It is found the structures and catalytic performances of the catalysts were highly affected by the preparation method. The catalyst prepared by sol-gel method had smaller average size of copper nanoparticles (about 3-4 nm, better copper dispersion, higher Cu+/C0 ratio and larger BET surface area, and higher DMO conversion and EG selectivity under the optimized reaction conditions.

  11. Energy transfer from argon resonance states to nitrogen, hydrogen, and nitric oxide

    International Nuclear Information System (INIS)

    Transfer of electronic energy from the resonance states Ar(1P1) and Ar(3P1) to diatomic nitrogen, hydrogen, and nitric oxide has been studied with a time-resolved quenching technique. Rate constants for energy transfer were deduced from the changes of the rate of decay of excited states corresponding to known changes of the density of the diatomic molecules. For Ar*--N2 the rate constants were 5.4 x 10-11 and 0.8 x 10-11 molecule-1 cm3 sec-1 for Ar(1P1) and Ar(3P1), respectively. For Ar*--H2, the measured rate constants were 22 x 10-11 and 21 x 10-11 molecule-1 cm3sec-1 for Ar(1P1) and Ar(3P1), respectively. The results for nitric oxide were 54 x 10-11 and 32 x 10-11 molecule-1 cm3sec-1 for Ar(1P1) and Ar(3P1), respectively

  12. Sewage-sludge-derived carbonaceous materials for catalytic wet hydrogen peroxide oxidation of m-cresol in batch and continuous reactors.

    Science.gov (United States)

    Yu, Yang; Wei, Huangzhao; Yu, Li; Wang, Wei; Zhao, Ying; Gu, Bin; Sun, Chenglin

    2016-01-01

    In this study, four sewage-sludge-derived carbonaceous materials (SWs) were evaluated for their catalytic wet hydrogen peroxide oxidation (CWPO) performance of m-cresol in batch reactor and continuous reactor, respectively. The SWs were produced by carbonization (SW); carbonization with the addition of CaO (CaO-SW); HNO3 pretreatment (HNO3-SW) and steam activation (Activated-SW). The properties of SW catalysts were assessed by thermogravimetric analysis, Brunauer-Emmett-Teller, Fourier Transform Infrared Spectroscopy, X-ray Fluorescence, Scanning electron microscopy, energy dispersive X-ray analysis and zeta potential. The results showed that SW treated by HNO3 (HNO3-SW) had a high conversion of m-cresol in batch reactor and continuous reactor, respectively. Under the conditions of batch reaction (Cm-cresol = 100 mg L(-1), CH2O2 = 15.7 mmol L(-1), initial pH=7.0, 0.5 g L(-1) catalyst, 80°C, 180 min adsorption and 210 min oxidation), the conversion of m-cresol reached 100% and total organic carbon removal was 67.1%. It had a high catalytic activity and stability on the treatment of m-cresol in CWPO for more than 1100 h. Furthermore, a possible reaction mechanism for the oxidation of m-cresol to 2-methyl-p-benzoquinone by CWPO was proposed. PMID:26109374

  13. Preparation, Characterization, and Enhanced Photo catalytic Hydrogen Evolution Activity of Y2Cu2O5-Based Compounds under Simulated Sunlight Irradiation

    International Nuclear Information System (INIS)

    Y2Cu2O5 photo catalyst was successfully prepared via solid state reaction and further combined with TiO2 by a sol-gel method and a solid phase method, respectively. For comparison, Pt Y2Cu2O5particles were loaded to prepare Pt- via a hydrogen reduction method. All the samples were characterized by thermogravimetry and differential thermal analysis (TG/DTA), X-ray diffraction (XRD), UV-vis diffuse reflectance spectroscopy (UV-vis DRS), and scanning electron microscopy (SEM) techniques. Photo catalytic H2 evolution activities of the as-obtained samples were evaluated from aqueous oxalic acid solution under simulated sunlight irradiation. The effects of photo catalyst concentration, TiO2 content, and composite method on the H2 evolution activities of the as-obtained photo catalysts were investigated. The results show that, when the concentration of photo catalyst is 0.8 gL-1, the TiO2 Y2Cu2O5 composite photo catalyst prepared by a sol-gel method exhibits the optimized photo catalytic activity, and the H2 production rate is 4.35 m mol with 30 wt.% content of TiO2

  14. Nickel-based xerogel catalysts: Synthesis via fast sol-gel method and application in catalytic hydrogenation of p-nitrophenol to p-aminophenol

    Science.gov (United States)

    Feng, Jin; Wang, Qiang; Fan, Dongliang; Ma, Lirong; Jiang, Deli; Xie, Jimin; Zhu, Jianjun

    2016-09-01

    In order to investigate the roles of three-dimensional network structure and calcium on Ni catalysts, the Ni, Ni-Al2O3, Ni-Ca-Al2O3 xerogel catalysts were successfully synthesized via the fast sol-gel process and chemical reduction method. The crystal structure of three different catalysts was observed with X-ray powder diffraction (XRD). Transmission electron microscopy (TEM), scanning electron microscopy (SEM) and nitrogen adsorption-desorption were employed to investigate the role of network structure of xerogel catalysts and the size distribution of Ni nanoparticles. The catalyst composition was determined by inductively coupled plasma-optical emission spectrometry (ICP-OES) measurement and energy-dispersive X-ray spectroscopy (EDS). Temperature-programmed reduction (TPR) experiments were carried out to investigate the reducibility of nickel species and the interaction between nickel species and alumina. The catalytic hydrogenation of p-nitrophenol to p-aminophenol was investigated over the prepared nickel-based xerogel catalysts. The conversion of p-nitrophenol was monitored by UV spectrophotometry and high performance liquid chromatography (HPLC). The results show that the catalysts are highly selective for the conversion of p-nitrophenol to p-aminophenol and the order of catalytic activities of the catalysts is Ni < Ni-Al2O3 < Ni-Ca-Al2O3. The catalysts were recycled and were used to evaluate the reutilization.

  15. Synthesis and Catalytic Performance of Graphene Modified CuO-ZnO-Al2O3 for CO2 Hydrogenation to Methanol

    Directory of Open Access Journals (Sweden)

    Zheng-juan Liu

    2014-01-01

    Full Text Available CuO-ZnO-Al2O3 and graphene nanosheet (GNS were synthesized by coprecipitation route and reduction of exfoliated graphite oxides method, respectively. GNS modified CuO-ZnO-Al2O3 nanocomposites were synthesized by high energy ball milling method. The structure, morphology, and character of the synthesized materials were studied by BET, XRD, TEM, and H2-TPR. It was found that by high energy ball milling method the CuO-ZnO-Al2O3 nanoparticles were uniformly dispersed on GNS surfaces. The catalytic performance for the methanol synthesis from CO2 hydrogenation was also tested. It was shown experimentally that appropriate incorporation of GNS into the CuO-ZnO-Al2O3 could significantly increase the catalyst activity for methanol synthesis. The 10 wt.% GNS modified CuO-ZnO-Al2O3 catalyst gave a methanol space time yield (STY of 92.5% higher than that on the CuO-ZnO-Al2O3 catalyst without GNS. The improved catalytic performance was attributed to the excellent promotion of GNS to dispersion of CuO and ZnO particles.

  16. Catalytic activity of Pd-Ni in the oxidation of hydrogen for the safety of nuclear power plant

    Directory of Open Access Journals (Sweden)

    Łomot Dariusz

    2016-03-01

    Full Text Available Pd-Ni/Al2O3 systems were investigated in the reaction of hydrogen oxidation in terms of their possible application as catalysts used in passive autocatalytic recombiners (PARs used in nuclear power plants. Testing experiments were carried out in a flowing system at different temperatures and humidity of the reaction mixture. The bimetallic catalysts exhibited higher response to the increase of temperature and higher resistance to inhibit water than the monometallic palladium catalyst. They showed excellent stability during a few tens of hours, similarly, like their monometallic counterpart. Our bimetallic catalysts of hydrogen oxidation can be used as cheaper alternatives to catalysts based on the precious metals in the hydrogen oxidation without loss of their activity over time.

  17. 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

  18. Enhancement of reaction rates for catalytic benzaldehyde hydrogenation and sorbitol dehydration in water solvent by addition of carbon dioxide

    Indian Academy of Sciences (India)

    Masayuki Shirai; Osamu Sato; Norihito Hiyoshi; Aritomo Yamaguchi

    2014-03-01

    The effect of pressured carbon dioxide on heterogeneous hydrogenation of benzaldehyde and homogeneous dehydration of sorbitol in water solvent was studied. Initial hydrogenation rates of benzaldehyde over a charcoal-supported palladium catalyst in water at 313 K were enhanced by the addition of carbon dioxide. The initial rate increased with an increase in carbon dioxide pressure and became a maximum at 5 MPa. Dehydration of sorbitol proceeded in water phase at 500 K and initial dehydration rates were enhanced by addition of 30 MPa of carbon dioxide.

  19. A Au/Cu2O-TiO2 system for photo-catalytic hydrogen production. A pn-junction effect or a simple case of in situ reduction?

    KAUST Repository

    Sinatra, Lutfan

    2015-02-01

    Photo-catalytic H2 production from water has been studied over Au-Cu2O nanoparticle deposited on TiO2 (anatase) in order to probe into both the plasmon resonance effect (Au nanoparticles) and the pn-junction at the Cu2O-TiO2 interface. The Au-Cu2O composite is in the form of ∼10 nm Au nanoparticles grown on ∼475 nm Cu2O octahedral nanocrystals with (111) facets by partial galvanic replacement. X-ray Photoelectron Spectroscopy (XPS) Cu2p and Auger L3M4,5M4,5 lines indicate that the surface of Cu2O is mainly composed of Cu+. The rate for H2 production (from 95 water/5 ethylene glycol; vol.%) over 2 wt.% (Au/Cu2O)-TiO2 is found to be ∼10 times faster than that on 2 wt.% Au-TiO2 alone. Raman spectroscopy before and after reaction showed the disappearance of Cu+ lines (2Eu) at 220 cm-1. These observations coupled with the induction time observed for the reaction rate suggest that in situ reduction from Cu+ to Cu0 occurs upon photo-excitation. The reduction requires the presence of TiO2 (electron transfer). The prolonged activity of the reaction (with no signs of deactivation) despite the reduction to Cu0 indicates that the latter takes part in the reaction by providing additional sites for the reaction, most likely as recombination centers for hydrogen atoms to form molecular hydrogen. This phenomenon provides an additional route for enhancing the efficiency and lifetime of Cu2O-TiO2 photocatalytic systems, beyond the usually ascribed pn-junction effect.

  20. On the role of charge transfer in the stabilization of weakly bound complexes involving water and hydrogen sulphide molecules

    International Nuclear Information System (INIS)

    Graphical abstract: A charge-displacement analysis allows to quantitatively assess charge-transfer effects in hydrogen-bonded complexes. Highlights: ► We compare water with hydrogen sulphide both interacting with krypton. ► In both cases the interaction possesses a definite charge transfer component. ► Charge-transfer differs slightly in the two systems and exhibits different stereoselectivity. - Abstract: Integral cross section data for collisions of water and hydrogen sulphide molecules with noble gas atoms, measured with the same apparatus under identical conditions and analyzed by exploiting the same potential model, provided a set of internally consistent potential parameters. Their critical comparison is exploited not only to identify those systems where the intermolecular bond is not simply due to the balancing of size repulsion with dispersion and induction attraction, but also to establish the amount of bond stabilization by charge-transfer effects. Such experimental findings are analyzed through extensive and accurate ab initio calculations, addressed at discovering the relevant differences in the basic features of the potential energy surfaces. In particular, we have analyzed in detail the prototype H2S, H2O–Kr systems and found pronounced differences in the dependence of the interaction nature and energy on the relative orientation of the colliding systems. Using the recently proposed charge-displacement analysis we have been able to quantitatively assess charge-transfer effects, which differ significantly in the two systems and exhibit different stereoselectivity. This casts further light on the specificity of water interactions.

  1. Ni(0-CMC-Na Nickel Colloids in Sodium Carboxymethyl-Cellulose: Catalytic Evaluation in Hydrogenation Reactions

    Directory of Open Access Journals (Sweden)

    Abdallah Karim

    2011-01-01

    Full Text Available A recyclable catalyst, Ni(0-CMC-Na, composed of nickel colloids dispersed in a water soluble bioorganic polymer, sodium carboxymethylcellulose (CMC-Na, was synthesized by a simple procedure from readily available reagents. The catalyst thus obtained is stable and highly active in alkene hydrogenations.

  2. Ni(0)-CMC-Na Nickel Colloids in Sodium Carboxymethyl-Cellulose: Catalytic Evaluation in Hydrogenation Reactions

    OpenAIRE

    Abdallah Karim; Larbi El Firdoussi; Issam Houssini; Mustapha Ait Ali; M. Carmen Puerta; Mohamed Anouar Harrad; Pedro Valerga

    2011-01-01

    A recyclable catalyst, Ni(0)-CMC-Na, composed of nickel colloids dispersed in a water soluble bioorganic polymer, sodium carboxymethylcellulose (CMC-Na), was synthesized by a simple procedure from readily available reagents. The catalyst thus obtained is stable and highly active in alkene hydrogenations.

  3. Catalytic activity of hydrophobic Pt/C/PTFE catalysts of different PTFE content for hydrogen-water liquid exchange reaction

    International Nuclear Information System (INIS)

    10%Pt/C catalysts were prepared by liquid reduction method. PTFE and Pt/ C catalysts were adhered to porous metal and hydrophobic Pt/C/PTFE catalysts were prepared. The structure and size of Pt crystal particles of Pt/C catalysts were analyzed by XRD, and their mean size was 3.1 nm. The dispersion state of Pt/C and PTFE was analyzed by SEM, and they had good dispersion mostly, but PTFE membrane could be observed on local parts of Pt/C/PTFE surface. Because of low hydrophobicity, Pt/C/ PTFE catalysts have low activity when the mass ratio of PTFE and Pt/C is 0.5: 1, and their catalytic activity increases markedly when the ratio is 1:1. When the ratio increases again, more Pt active sites would be covered by PTFE and interior diffusion effect would increase, which result in the decrease of catalytic activity of Pt/C/PTFE. By PTFE pretreatment of porous metal carrier, the activity of Pt/C/PTFE catalysts decreases when the mass ratio of PTFE and Pt/C is 0.5:1, and their activity decreases when the mass ratio is 1:1. (authors)

  4. Gas cleaning and hydrogen sulfide removal for COREX coal gas by sorption enhanced catalytic oxidation over recyclable activated carbon desulfurizer.

    Science.gov (United States)

    Sun, Tonghua; Shen, Yafei; Jia, Jinping

    2014-02-18

    This paper proposes a novel self-developed JTS-01 desulfurizer and JZC-80 alkaline adsorbent for H2S removal and gas cleaning of the COREX coal gas in small-scale and commercial desulfurizing devices. JTS-01 desulfurizer was loaded with metal oxide (i.e., ferric oxides) catalysts on the surface of activated carbons (AC), and the catalyst capacity was improved dramatically by means of ultrasonically assisted impregnation. Consequently, the sulfur saturation capacity and sulfur capacity breakthrough increased by 30.3% and 27.9%, respectively. The whole desulfurizing process combined selective adsorption with catalytic oxidation. Moreover, JZC-80 adsorbent can effectively remove impurities such as HCl, HF, HCN, and ash in the COREX coal gas, stabilizing the system pressure drop. The JTS-01 desulfurizer and JZC-80 adsorbent have been successfully applied for the COREX coal gas cleaning in the commercial plant at Baosteel, Shanghai. The sulfur capacity of JTS-01 desulfurizer can reach more than 50% in industrial applications. Compared with the conventional dry desulfurization process, the modified AC desulfurizers have more merit, especially in terms of the JTS-01 desulfurizer with higher sulfur capacity and low pressure drop. Thus, this sorption enhanced catalytic desulfurization has promising prospects for H2S removal and other gas cleaning. PMID:24456468

  5. Cross-Species Analysis of Protein Dynamics Associated with Hydride and Proton Transfer in the Catalytic Cycle of the Light-Driven Enzyme Protochlorophyllide Oxidoreductase.

    Science.gov (United States)

    Hoeven, Robin; Hardman, Samantha J O; Heyes, Derren J; Scrutton, Nigel S

    2016-02-16

    Experimental interrogation of the relationship between protein dynamics and enzyme catalysis is challenging. Light-activated protochlorophyllide oxidoreductase (POR) is an excellent model for investigating this relationship because photoinitiation of the reaction cycle enables coordinated turnover in a "dark-assembled" ternary enzyme-substrate complex. The catalytic cycle involves sequential hydride and proton transfers (from NADPH and an active site tyrosine residue, respectively) to the substrate protochlorophyllide. Studies with a limited cross-species subset of POR enzymes (n = 4) have suggested that protein dynamics associated with hydride and proton transfer are distinct [Heyes, D. J., Levy, C., Sakuma, M., Robertson, D. L., and Scrutton, N. S. (2011) J. Biol. Chem. 286, 11849-11854]. Here, we use steady-state assays and single-turnover laser flash spectroscopy to analyze hydride and proton transfer dynamics in an extended series of POR enzymes taken from many species, including cyanobacteria, algae, embryophytes, and angiosperms. Hydride/proton transfer in all eukaryotic PORs is faster compared to prokaryotic PORs, suggesting active site architecture has been optimized in eukaryotic PORs following endosymbiosis. Visible pump-probe spectroscopy was also used to demonstrate a common photoexcitation mechanism for representative POR enzymes from different branches of the phylogenetic tree. Dynamics associated with hydride transfer are localized to the active site of all POR enzymes and are conserved. However, dynamics associated with proton transfer are variable. Protein dynamics associated with proton transfer are also coupled to solvent dynamics in cyanobacterial PORs, and these networks are likely required to optimize (shorten) the donor-acceptor distance for proton transfer. These extended networks are absent in algal and plant PORs. Our analysis suggests that extended networks of dynamics are disfavored, possibly through natural selection. Implications for

  6. Preparation and Characterization of Polymer-Stabilized Ruthenium-Platinum and Ruthenium-Palladium Bimetallic Colloids and Their Catalytic Properties for Hydrogenation of o-Chloronitrobenzene.

    Science.gov (United States)

    Liu; Yu; Liu; Zheng

    1999-06-15

    Colloidal dispersions of poly(N-vinyl-2-pyrrolidone) (PVP)-stabilized ruthenium-platinum and ruthenium-palladium bimetallic colloids were prepared by NaBH4 reduction of the corresponding mixed-metal salts at room temperature and characterized by TEM, XPS, and XRD. The resulting bimetallic colloids were used as catalysts for the selective hydrogenation of o-chloronitrobenzene (o-CNB) in methanol at 303 K under 0.1 MPa of hydrogen. It was observed that the catalytic performance of PVP-stabilized ruthenium-platinum colloids (PVP-Ru/Pt) and ruthenium-palladium colloids (PVP-Ru/Pd) was dependent on their compositions and could be remarkably affected by some added metal cations. In the presence of cobalt ion, nearly 100% selectivity to o-chloroaniline (o-CAN) was achieved over PVP-Ru/Pt colloids at 100% conversion of o-CNB, with an activity two orders of magnitude higher than that of monometallic PVP-Ru colloid. Copyright 1999 Academic Press. PMID:10339363

  7. Facile synthesis of near-monodisperse Ag-Ni core-shell nanoparticles and their application for catalytic generation of hydrogen

    Energy Technology Data Exchange (ETDEWEB)

    Guo Huizhang; Chen Yuanzhi; Chen Xiaozhen; Wen Ruitao; Yue Guanghui; Peng Dongliang, E-mail: yuanzhi@xmu.edu.cn, E-mail: dlpeng@xmu.edu.cn [Department of Materials Science and Engineering, College of Materials, Xiamen University, Xiamen 361005 (China)

    2011-05-13

    Magnetically recyclable Ag-Ni core-shell nanoparticles have been fabricated via a simple one-pot synthetic route using oleylamine both as solvent and reducing agent and triphenylphosphine as a surfactant. As characterized by transmission electron microscopy (TEM), the as-synthesized Ag-Ni core-shell nanoparticles exhibit a very narrow size distribution with a typical size of 14.9 {+-} 1.2 nm and a tunable shell thickness. UV-vis absorption spectroscopy study shows that the formation of a Ni shell on Ag core can damp the surface plasmon resonance (SPR) of the Ag core and lead to a red-shifted SPR absorption peak. Magnetic measurement indicates that all the as-synthesized Ag-Ni core-shell nanoparticles are superparamagnetic at room temperature, and their blocking temperatures can be controlled by modulating the shell thickness. The as-synthesized Ag-Ni core-shell nanoparticles exhibit excellent catalytic properties for the generation of H{sub 2} from dehydrogenation of sodium borohydride in aqueous solutions. The hydrogen generation rate of Ag-Ni core-shell nanoparticles is found to be much higher than that of Ag and Ni nanoparticles of a similar size, and the calculated activation energy for hydrogen generation is lower than that of many bimetallic catalysts. The strategy employed here can also be extended to other noble-magnetic metal systems.

  8. Facile synthesis of near-monodisperse Ag-Ni core-shell nanoparticles and their application for catalytic generation of hydrogen

    International Nuclear Information System (INIS)

    Magnetically recyclable Ag-Ni core-shell nanoparticles have been fabricated via a simple one-pot synthetic route using oleylamine both as solvent and reducing agent and triphenylphosphine as a surfactant. As characterized by transmission electron microscopy (TEM), the as-synthesized Ag-Ni core-shell nanoparticles exhibit a very narrow size distribution with a typical size of 14.9 ± 1.2 nm and a tunable shell thickness. UV-vis absorption spectroscopy study shows that the formation of a Ni shell on Ag core can damp the surface plasmon resonance (SPR) of the Ag core and lead to a red-shifted SPR absorption peak. Magnetic measurement indicates that all the as-synthesized Ag-Ni core-shell nanoparticles are superparamagnetic at room temperature, and their blocking temperatures can be controlled by modulating the shell thickness. The as-synthesized Ag-Ni core-shell nanoparticles exhibit excellent catalytic properties for the generation of H2 from dehydrogenation of sodium borohydride in aqueous solutions. The hydrogen generation rate of Ag-Ni core-shell nanoparticles is found to be much higher than that of Ag and Ni nanoparticles of a similar size, and the calculated activation energy for hydrogen generation is lower than that of many bimetallic catalysts. The strategy employed here can also be extended to other noble-magnetic metal systems.

  9. EPR spectroscopy of catalytic systems based on nickel complexes of 1,4-diaza-1,3-butadiene (alpha-diimine) ligands in hydrogenation and polymerization reactions

    International Nuclear Information System (INIS)

    The catalytic systems based on .-diimine complexes of Ni(0) and Ni(II) of the general formulas NiBr2(DAD-R) (R = -C3H7 or -CH3) and Ni(DAD-CH3)2 (DAD(-C3H7) = 1,4-bis(2,6-diiso-propylphenyl)-2,3-(dimethyl-1,4-diazabuta-1,3-diene, DAD(-CH3) = 1,4-bis 2,6-dimethylphenyl)-2,3-dimethyl-1,4-diazabuta-1,3-diene), with Lewis acids (AlEt3, AlEt2Cl, AlEtCl2, B(F5C6)3, BF3 centre dot OEt2) in hydrogenation and polymerization reactions were investigated by the EPR spectroscopy method. The Ni(I) complexes of a (DAD-R)NiX2AlXy(C2H5)3-y composition (instead of the aluminum atom may be a boron atom) were identified where R = -CH3 or -C3H7, X = Br, X = Cl or -C2H5. The .-diimines radical-anions are included in the derivatives of aluminum or boron. It is found that there occur oxidation reactions between Ni(DAD-CH3)2 and aluminum organic compounds or boron derivatives, resulting in the formation of paramagnetic complexes. It is shown that there is no direct relationship between activity in polymerization or hydrogenation reactions and concentration of paramagnetic particles.

  10. Microwave-irradiated polyol method synthesis of Pt/C catalysts and its catalytic activities for hydrogen-water liquid exchange reaction

    International Nuclear Information System (INIS)

    Pt/C catalysts with isopropanol as both dispersant and reducing agent were synthesized by microwave-irradiated polyol method. The microstructures of the catalysts were characterized by XRD and TEM. The effects of capping agents, pH and heating rate on Pt particle size were studied. Then Pt/C catalysts were loaded on foam nickel with polytetrafluoroethylene latex to obtain hydrophobic catalysts, and their catalytic activities for hydrogen-water liquid phase exchange reaction were investigated. The results show that compared to the non-capped Pt/C catalysts, the average size of Pt particles in sodium acetate, sodium glycollate and disodium hydrogen citrate capped Pt/C catalysts decreases from 4.4 nm to 2.3, 2.5, and 2.3 nm respectively, and the agglomeration of Pt particles becomes obscure. The mean size of Pt particles in Pt/C catalysts decreases evidently with the increasing of the heating rate. However, the mean sizes of Pt particles in the Pt/C catalysts prepared with different pH of the synthesis solution are similar. The activity of the hydrophobic catalysts with capping agents is high for hydro- gen-water liquid exchange reaction, and is enhanced by decreasing the average particle size, in the range of 2.3-4.4 nm. (authors)

  11. Study on hydrogen production by catalytic reforming of bio-oil-methanol mixture%生物油-甲醇催化转化制氢

    Institute of Scientific and Technical Information of China (English)

    韩红睿; 张瑞芹; 徐兴敏; 张长森; 刘永刚

    2011-01-01

    Using bio-oil-tnethanol as the raw material, the nickel-based reforming catalyst for hydrogen production prepared in the laboratory was investigated in the fixed micro-reactor. The catalysts before and after reaction were characterized by XRD,BET and SEM. The condensates collected after gasification were analyzed by GC-MS. The results showed that NiCeMg/olivine catalyst exhibited good catalytic activity and good properties of resistance to carbon deposition. The hydrogen yield of 38. 52% and carbon conversion of 68. 29% were attained under the the optimum reaction condition.%以生物油-甲醇为原料,在微型固定反应装置上考察实验室合成镍基催化剂重整制氢的催化效率.对反应前后的催化剂进行XRD、BET和SEM表征分析,并对冷凝液做GC - MS分析.研究发现,实验室自制的NiCeMg/olivine催化剂具有较好的催化活性和一定的抗积炭性能.在选择的最佳反应条件下,氢气产率和碳转化率分别为38.52%和68.29%.

  12. Use of Heterogenized Metal Complexes in Hydrogenation Reactions: Comparison of Hydrogenation and CTH Reactions.

    Czech Academy of Sciences Publication Activity Database

    Bata, P.; Zsigmond, A.; Gyémánt, M.; Czeglédi, A.; Klusoň, Petr

    2015-01-01

    Roč. 41, č. 12 (2015), s. 9281-9294. ISSN 0922-6168. [Pannonian Symposium on Catalysis /12./. Castle Trest, 16.09.2014-20.09.2014] Institutional support: RVO:67985858 Keywords : catalytic transfer hydrogenation * iron-phthalocyanine catalyst * chemoselectivity Subject RIV: CI - Industrial Chemistry, Chemical Engineering Impact factor: 1.221, year: 2014

  13. 四氯化碳液相催化加氢反应动力学的研究%KINETIC STUDIES ON THE CATALYTIC HYDROGENATION OF CARBON TETRACHLORIDE TO CHLOROFORM IN LIQUID PHASE

    Institute of Scientific and Technical Information of China (English)

    毛建新; 蒋晓原; 陆维敏; 郑小明

    2001-01-01

    Carbon tetrachloride is an ozone-depleting chemical, while chloroform is not. Therefore it is important for the catalytic hydrodechlorination of CCl4 to CHCl3. In this paper, kinetics on the catalytic hydrogenation of carbon tetrachloride to chloroform in liquid phase was studied. A reaction mechanism was proposed. Hydrogen molecular was activated on the surface of catalyst, the activated hydrogen atom then reacted with CCl4 in the solution and produced CHCl3. A definite kinetic equation could be deduced from the reaction mechanism. The reaction rate constant is concerned with the intial concentration of CCl4 in the solution, pressure, reaction temperature and the concentration of active center. All these factors were investigated over Pt-Pd/C catalyst and fit in with the kinetic equation. The activation energy of the reaction is 86?KJ/mol according to the experimental results.

  14. Experimental, kinetic and numerical modeling of hydrogen production by catalytic reforming of crude ethanol over a commercial catalyst in packed bed tubular reactor and packed bed membrane reactor

    International Nuclear Information System (INIS)

    The demand for hydrogen energy has increased tremendously in recent years essentially because of the increase in the word energy consumption as well as recent developments in fuel cell technologies. The energy information administration has projected that world energy consumption will increase by 59% over the next two decades, from 1999 to 2020, in which the largest share is still dominated by fossil fuels (oil, natural gas and coal). Carbon dioxide (CO2) emissions resulting from the combustion of these fossil fuels currently are estimated to account for three-fourth of human-caused CO2 emissions worldwide. Greenhouse gas emission, including CO2, should be limited, as recommended at the Kyoto Conference, Japan, in December 1997. In this regard, hydrogen (H2) has a significant future potential as an alternative fuel that can solve the problems of CO2 emissions as well as the emissions of other air contaminants. One of the techniques to produce hydrogen is by reforming of hydrocarbons or biomass. Crude ethanol (a form of biomass, which essentially is fermentation broth) is easy to produce, is free of sulphur, has low toxicity, and is also safe to handle, transport and store. In addition, crude ethanol consists of oxygenated hydrocarbons, such as ethanol, lactic acid, glycerol, and maltose. These oxygenated hydrocarbons can be reformed completely to H2 and CO2, the latter of which could be separated from H2 by membrane technology. This provides for CO2 capture for eventual storage or destruction. In the case of using crude ethanol, this will result in negative CO2, emissions. In this paper, we conducted experimental work on production of hydrogen by the catalytic reforming of crude ethanol over a commercial promoted Ni-based catalyst in a packed bed tubular reactor as well as a packed bed membrane reactor. As well, a rigorous numerical model was developed to simulate this process in both the catalytic packed bed tubular reactor and packed bed membrane reactor. The

  15. Molybdenum(VI) network polymers based on anion-π interaction and hydrogen bonding: Synthesis, crystal structures and oxidation catalytic application

    Science.gov (United States)

    Li, Jia; Wang, Ge; Shi, Zhan; Yang, Mu; Luck, Rudy L.

    2009-11-01

    A crystallographic investigation of anion-π interactions and hydrogen bonds on the preferred structural motifs of molybdenum(VI) complexes has been carried out. Two molybdenum(VI) network polymers MoO 2F 4·(Hinca) 2 ( 1) and MoO 2F 3(H 2O)·(Hinpa) ( 2), where inca = isonicotinamide and inpa = isonipecotamide, have been synthesized, crystallographically characterized and successfully applied to alcohol oxidation reaction. Complex 1 crystallizes in the monoclinic space C2/ c: a = 16.832(3) Å, b = 8.8189(15) Å, c = 12.568(2) Å, β = 118.929(3)°, V = 1560.1(5) Å 3, Z = 4. Complex 2 crystallizes in the triclinic space P-1: a = 5.459(2) Å, b = 9.189(4) Å, c = 12.204(5) Å, α = 71.341(6)°, β = 81.712(7)°, γ = 77.705(7)°, V = 564.8(4) Å 3, Z = 2. Complex 1 consists of hydrogen bonding and anion-π interactions, both of which are considered as important factors for controlling the geometric features and packing characteristics of the crystal structure. The geometry of the sandwich complex of [MoO 2F 4] 2- with two pyridine rings indicates that the anion-π interaction is an additive and provides a base for the design and synthesis of new complexes. For complex 2, the anions and the protonated inpa ligands form a 2D supramolecular network by four different types of hydrogen contacts (N-H⋯F, N-H⋯O, O-H⋯F and O-H⋯O). The catalytic ability of complexes 1 and 2 has also been evaluated by applying them to the oxidation of benzyl alcohol with TBHP as oxidant.

  16. Preparation of Dendritic Carbosilane-supported Palladium Catalyst and Its Catalytic Activity in Hydrogenation of Organic Compounds

    Institute of Scientific and Technical Information of China (English)

    2005-01-01

    The preparation of palladium complex from PdCl2·2H2O and earbosilane dendrimers with peripheral aminopropyl groups was described. The compound obtained was characterized by IR, 1H NMR, X-ray photoelectron spectroscopy (XPS) and inductively coupled plasma atomic emission spectrometric (ICP-AES) spectroscopy respectively. The metal complex was employed as catalyst in hydrogenation of organic compounds. The high activity of the complex was probably due to the formation of the eoordinatively unsaturated palladium.

  17. Synthesis of zirconia-immobilized copper chelates for catalytic decomposition of hydrogen peroxide and the oxidation of polycyclic aromatic hydrocarbons

    Czech Academy of Sciences Publication Activity Database

    Baldrian, Petr; Merhautová, Věra; Cajthaml, Tomáš; Nerud, František; Stopka, Pavel; Gorbacheva, O.; Hrubý, Martin; Beneš, Milan J.

    2008-01-01

    Roč. 72, č. 11 (2008), s. 1721-1726. ISSN 0045-6535 R&D Projects: GA AV ČR IBS5020306 Institutional research plan: CEZ:AV0Z50200510; CEZ:AV0Z40320502; CEZ:AV0Z40500505 Keywords : degradation * polycyclic aromatic hydrocarbons * hydrogen peroxide Subject RIV: EE - Microbiology, Virology Impact factor: 3.054, year: 2008

  18. Hydrogenation of unactivated enamines to tertiary amines: rhodium complexes of fluorinated phosphines give marked improvements in catalytic activity

    Directory of Open Access Journals (Sweden)

    Sergey Tin

    2015-05-01

    Full Text Available In the hydrogenation of sluggish unactivated enamine substrates, Rh complexes of electron-deficient phosphines are demonstrated to be far more reactive catalysts than those derived from triphenylphosphine. These operate at low catalyst loadings (down to 0.01 mol % and are able to reduce tetrasubstituted enamines. The use of the sustainable and environmentally benign solvent (R-limonene for the reaction is also reported with the amine isolated by acid extraction.

  19. Synthesis and catalytic activity of histidine-based NHC ruthenium complexes

    OpenAIRE

    Monney, Angèle; Venkatachalam, Galmari; Albrecht, Martin

    2011-01-01

    Main-chain C,N-protected histidine has been successfully alkylated at both side-chain nitrogens. The corresponding histidinium salt was metallated with ruthenium(II) by a transmetalation procedure, thus providing histidine-derived NHC ruthenium complexes. These bio-inspired comsxsxsplexes show appreciable activity in the catalytic transfer hydrogenation of ketones. peer-reviewed

  20. Engineering design elements of a two-phase thermosyphon to transfer nuclear thermal energy to a hydrogen plant

    Science.gov (United States)

    Sabharwall, Piyush

    Two hydrogen production processes, both powered by Next Generation Nuclear Plant (NGNP), are currently under investigation at the Idaho National Laboratory. The first is high-temperature steam electrolysis utilizing both heat and electricity and the second is thermo-chemical production through the sulfur-iodine process primarily utilizing heat. Both processes require high temperature (>850°C) for enhanced efficiency; temperatures indicative of NGNP. Safety and licensing mandates prudently dictate that the NGNP and the hydrogen production facility be physically isolated, perhaps requiring separation of over 100m. There are several options to transferring multi-megawatt thermal power over such a distance. One option is simply to produce only electricity, transfer by wire to the hydrogen plant, and then reconvert the electric energy to heat via Joule or induction heating. Electrical transport, however, suffers energy losses of 60-70% due to the thermal to electric conversion inherent in the Brayton cycle. A second option is thermal energy transport via a single-phase forced convection loop where a fluid is mechanically pumped between heat exchangers at the nuclear and hydrogen plants. High temperatures, however, present unique materials and pumping challenges. Single phase, low pressure helium is an attractive option for NGNP, but is not suitable for a single purpose facility dictated to hydrogen production because low pressure helium requires higher pumping power and makes the process very inefficient. A third option is two-phase heat transfer utilizing a high temperature thermosyphon. Heat transport occurs via evaporation and condensation, and the heat transport fluid is re-circulated by gravitational force. Thermosyphon has the capability to transport heat at high rates over appreciable distances, virtually isothermally and without any requirement for external pumping devices. For process heat, intermediate heat exchangers (IHX) are desired to transfer heat from

  1. In Situ Catalytic Hydrogenation of Biomass-Derived Methyl Levulinate to γ-Valerolactone in Methanol.

    Science.gov (United States)

    Tang, Xing; Li, Zheng; Zeng, Xianhai; Jiang, Yetao; Liu, Shijie; Lei, Tingzhou; Sun, Yong; Lin, Lu

    2015-05-11

    In this work, the hydrocyclization of methyl levulinate (ML) to γ-valerolactone (GVL) was performed in MeOH over an in situ prepared nanocopper catalyst without external H2 . This nanocopper catalyst served as a dual-functional catalyst for both hydrogen production by MeOH reforming and hydrogenation of ML. Nearly quantitative ML conversion with a GVL selectivity of 87.6 % was achieved at 240 °C in 1 h in MeOH under a nitrogen atmosphere. ML in the methanolysis products of cellulose also could be hydrogenated effectively to GVL over this nanocopper catalyst even in the presence of humins to give an ML conversion of 94.1 % and a GVL selectivity of 73.2 % at 240 °C in 4 h. The absorption behavior of humins on the surface of the nanocopper catalyst was observed, which resulted in a pronounced increase in the acidic sites of the nanocopper catalyst that facilitate ring-opening and the hydrocarboxylation/alkoxycarbonylation of GVL to byproducts. PMID:25873556

  2. Mass and heat transfer on B7 structured packing in the separation of hydrogen isotopes by distillation

    International Nuclear Information System (INIS)

    The paper presents theoretical and experimental data concerning mass and heat transfer on B7 ordered packing, at deuterium separation by distillation. The first section of the paper is dedicated to the mass transfer study of hydrogen distillation, while the second section deals with mass and heat transfer in water distillation. A mathematical model was worked out and compared with experimental data, obtained from two laboratory distillation plants for deuterium separation. From the first plant experimental data concerning B7 ordered packing efficiency of hydrogen cryogenic distillation at 250 deg. C level were obtained. Data concerning mass and heat transfer on the same packing in deuterium separation by water vacuum distillation at 60 deg. C level were obtained in the second plant. HUT values, mass and heat transfer coefficients both theoretically evaluated and experimentally determined were found to be comparable with those obtained from chemical industry separation processes. The fact justifies the use of multi-tubular column model for description of transfer processes in distillation columns equipped with B7 structured packing. (authors)

  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. Electrochemical studies of a reconstituted photosynthetic electron-transfer chain or towards a biomimetic photoproduction of hydrogen

    International Nuclear Information System (INIS)

    The aim of this work is to find an efficient process to convert solar energy into hydrogen. The electrons transfers in reconstituted photosynthetic chains have been particularly studied with the aims 1)in one hand, to better understand the interactions of the different molecules of the photosynthetic chain in order to optimize the changes of the entire organisms for hydrogen production 2)in another hand, to insert the hydrogenases in a photosynthetic chain and then to photo reduce them in order to obtain kinetic data to better understand how it works. (O.M.)

  5. Transfer phenomena on a stage of a column for hydrogen isotope separation by cryogenic distillation

    International Nuclear Information System (INIS)

    The paper reports a study of the transfer phenomena that occurred in a stage of a cryogenic distillation column for multicomponent mixtures with application to the hydrogen isotopes H2, D2, T2. To approach the problem we worked in the frame of molecular theory of gases. We considered that for vapor phase the transport phenomena can be described by the multicomponent law of diffusion for dilute gases. We made the assumption that at the boundary the vapor phase is in thermodynamic equilibrium with the liquid phase but the bulk of the vapor phase is initially not in equilibrium. The multicomponent diffusion coefficient were computed considering a Lennard-Jones potential of interaction between molecules. We used cylindrical coordinates and considered axial symmetry. A non-steady system of two equations with partial derivatives of first and second order resulted. In our model we also introduced a computational procedure for the state equation of the mixture, with quantum correction for the second Virial coefficient. The results were compared with the predictions of the traditional mathematical model which considers all the components of the mixture in the two phases (vapor and liquid) to be in thermodynamic equilibrium. The differences between the results obtained with the two models are significant in what concerns pressure variation and especially the values of the concentration at the feed of distillation column

  6. Dinuclear Tetrapyrazolyl Palladium Complexes Exhibiting Facile Tandem Transfer Hydrogenation/Suzuki Coupling Reaction of Fluoroarylketone

    KAUST Repository

    Dehury, Niranjan

    2016-07-18

    Herein, we report an unprecedented example of dinuclear pyrazolyl-based Pd complexes exhibiting facile tandem catalysis for fluoroarylketone: Tetrapyrazolyl di-palladium complexes with varying Pd-Pd distances efficiently catalyze the tandem reaction involving transfer hydrogenation of fluoroarylketone to the corresponding alcohol and Suzuki-Miyaura cross coupling reaction of the resulting fluoroarylalcohol under moderate reaction conditions, to biaryl alcohol. The complex with the shortest Pd-Pd distance exhibits the highest tandem activity among its di-metallic analogues, and exceeds in terms of activity and selectivity the analogous mononuclear compound. The kinetics of the reaction indicates clearly that reductive transformation of haloarylketone into haloaryalcohol is the rate determining step in the tandem reaction. Interestingly while fluoroarylketone undergoes the multistep tandem catalysis, the chloro- and bromo-arylketones undergo only a single step C-C coupling reaction resulting in biarylketone as the final product. Unlike the pyrazole based Pd compounds, the precursor PdCl2 and the phosphine based relevant complexes (PPh3)2PdCl2 and (PPh3)4Pd are found to be unable to exhibit the tandem catalysis.

  7. Multidisciplinary approaches to solar hydrogen

    OpenAIRE

    Bren, Kara L.

    2015-01-01

    This review summarizes three different approaches to engineering systems for the solar-driven evolution of hydrogen fuel from water: molecular, nanomaterials and biomolecular. Molecular systems have the advantage of being highly amenable to modification and detailed study and have provided great insight into photophysics, electron transfer and catalytic mechanism. However, they tend to display poor stability. Systems based on nanomaterials are more robust but also are more difficult to synthe...

  8. Heteropolymolybdate as a New Reaction-controlled Phase-transfer Catalyst for Efficient Alcohol Oxidation with Hydrogen Peroxide

    Institute of Scientific and Technical Information of China (English)

    Zhi Huan WENG; Jin Yan WANG; Xi Gao JIAN

    2006-01-01

    A new catalytic process for the synthesis of aldehyde from alcohol by oxidation with H2O2 with high selectivity was studied. In this system, heteropolymolybdate [C7H7N(CH3)3]3{PO4[MoO(O2)2]4} was utilized as the reaction-controlled phase-transfer catalyst to catalyze oxidation of benzyl and aliphatic alcohols. The molar ratio of H2O2 and alcohol was 0.75, no other by-products were detected by gas chromatography, the results of oxidation reaction indicated that the catalyst has high activity and stability.

  9. Pd/Graphene catalytic hydrogenation of benzoquinone to hydroquinone%钯/石墨烯催化苯醌加氢制备氢醌

    Institute of Scientific and Technical Information of China (English)

    杨敬贺; 郁清涛; 毛立群

    2015-01-01

    采用微波辅助加热还原法合成了钯/石墨烯(Pd/G)、钯/活性炭(Pd/AC)、钯/石墨(Pd/Graphite)和钯/二氧化硅(Pd/SiO2),并使用透射电子显微镜观测了钯的形貌及在载体上的分散性。将负载型钯催化剂用于苯醌加氢反应,结果显示,Pd/G催化剂的活性最高,苯醌的转化率达到99%,氢醌的选择性为100%,并且循环7次后催化剂仍保持着较高的转化率和选择性。结构表征表明,石墨烯担载的钯纳米粒子的粒径约为5 nm ,无明显团聚。实验进一步考察了反应溶剂(甲醇、乙醇、丙酮、正丙醇、异丙醇、正丁醇)对 Pd/G催化苯醌加氢反应的影响,结果表明该反应对溶剂较为敏感,其中甲醇和丙酮较适宜作为反应溶剂。当以甲醇作为溶剂时,苯醌的转化率为98%,氢醌选择性为99%;以丙酮为溶剂时,苯醌转化率为98%,氢醌选择性为90%。研究工作表明,作为载体,石墨烯对钯催化剂的催化效果起着稳定和增强作用。%In the present study ,we exploited G as a support for palladium nanoparticles by mi‐crowave assisted reduction of palladium acetate with graphene under hydrogen atmosphere .In the same method ,we also employed graphite ,active carbon and silica as carrier for synthesis palladium graphite (Pd/Graphite) ,palladium active carbon (Pd/AC) and palladium silica (Pd/SiO2 ) .The hydrogenation of benzoquinone reaction has been selected as model reaction for e‐valuating G -based palladium catalysts (Pd/G) ,and the morphology and dispersion of palla‐dium on the carrier were observed by TEM .We utilized the supported palladium catalysts for benzoquinone hydrogenation reaction .The results imply that the Pd/G catalyst shows the high‐est activity .T he conversion of benzoquinone reached 99% and the selectivity to hydroquinone was 100% .In addtion ,the catalytic performance of Pd/G catalyst remained

  10. Ruthenium(0) nanoclusters stabilized by a Nanozeolite framework: isolable, reusable, and green catalyst for the hydrogenation of neat aromatics under mild conditions with the unprecedented catalytic activity and lifetime.

    Science.gov (United States)

    Zahmakiran, Mehmet; Tonbul, Yalçin; Ozkar, Saim

    2010-05-12

    The hydrogenation of aromatics is a ubiquitous chemical transformation used in both the petrochemical and specialty industry and is important for the generation of clean diesel fuels. Reported herein is the discovery of a superior heterogeneous catalyst, superior in terms of catalytic activity, selectivity, and lifetime in the hydrogenation of aromatics in the solvent-free system under mild conditions (at 25 degrees C and 42 +/- 1 psig initial H(2) pressure). Ruthenium(0) nanoclusters stabilized by a nanozeolite framework as a new catalytic material is reproducibly prepared from the borohydride reduction of a colloidal solution of ruthenium(III)-exchanged nanozeolites at room temperature and characterized by using ICP-OES, XRD, XPS, DLS, TEM, HRTEM, TEM/EDX, mid-IR, far-IR, and Raman spectroscopy. The resultant ruthenium(0) nanoclusters hydrogenate neat benzene to cyclohexane with 100% conversion under mild conditions (at 25 degrees C and 42 +/- 1 psig initial H(2) pressure) with record catalytic activity (initial TOF = 5430 h(-1)) and lifetime (TTO = 177 200). They provide exceptional catalytic activity not only in the hydrogenation of neat benzene but also in the solvent-free hydrogenation of methyl substituted aromatics such as toluene, o-xylene, and mesitylene under otherwise identical conditions. Moreover, they are an isolable, bottleable, and reusable catalyst in the hydrogenation of neat aromatics. When the isolated ruthenium(0) nanoclusters are reused, they retain 92% of their initial catalytic activity even for the third run in the hydrogenation of neat benzene under the same conditions as those of the first run. The work reported here also includes (i) far-infrared spectroscopic investigation of nanozeolite, ruthenium(III)-exchanged-nanozeolite, and ruthenium(0) nanoclusters stabilized by a nanozeolite framework, indicating that the host framework remains intact after the formation of a nanozeolite framework stabilized ruthenium(0) nanoclusters; (ii) the

  11. Trends in Ground-State Entropies for Transition Metal Based Hydrogen Atom Transfer Reactions

    Energy Technology Data Exchange (ETDEWEB)

    Mader, Elizabeth A.; Manner, Virginia W.; Markle, Todd F.; Wu, Adam; Franz, James A.; Mayer, James M.

    2009-03-10

    Reported herein are thermochemical studies of hydrogen atom transfer (HAT) reactions involving transition metal H-atom donors MIILH and oxyl radicals. [FeII(H2bip)3]2+, [FeII(H2bim)3]2+, [CoII(H2bim)3]2+ and RuII(acac)2(py-imH) [H2bip = 2,2’-bi-1,4,5,6-tetrahydro¬pyrimidine, H2bim = 2,2’-bi-imidazoline, acac = 2,4-pentandionato, py-imH = 2-(2’-pyridyl)¬imidazole)] each react with TEMPO (2,2,6,6-tetramethyl-1-piperidinoxyl) or tBu3PhO• (2,4,6-tri-tert-butylphenoxyl) to give the deprotonated, oxidized metal complex MIIIL, and TEMPOH or tBu3PhOH. Solution equilibrium measurements for the reactions of Co and Fe complexes with TEMPO show a large, negative ground-state entropy for hydrogen atom transfer: ΔSºHAT = -30 ± 2 cal mol-1 K-1 for the two iron complexes and -41 ± 2 cal mol-1 K-1 for [CoII(H2bim)3]2+. The ΔSºHAT for TEMPO + RuII(acac)2(py-imH) is much closer to zero, 4.9 ± 1.1 cal mol-1 K-1. Calorimetric measurements quantitatively confirm the enthalpy of reaction for [FeII(H2bip)3]2+ + TEMPO, thus also confirming ΔSºHAT. Calorimetry on TEMPOH + tBu3PhO• gives ΔHºHAT = 11.2 ± 0.5 kcal mol-1 which matches the enthalpy predicted from the difference in literature solution BDEs. An evaluation of the literature BDEs of both TEMPOH and tBu3PhOH is briefly presented and new estimates are included on the relative enthalpy of solvation for tBu3PhO• vs. tBu3PhOH. The primary contributor to the large magnitude of the ground-state entropy |ΔSºHAT| for the metal complexes is vibrational entropy, ΔSºvib. The common assumption that ΔSºHAT ≈ 0 for HAT reactions, developed for organic and small gas phase molecules, does not hold for transition metal based HAT reactions. The trend in magnitude of |ΔSºHAT| for reactions with TEMPO, RuII(acac)2(py-imH) << [FeII(H2bip)3]2+ = [FeII(H2bim)3]2+ < [CoII(H2bim)3]2+, is surprisingly well predicted by the trends for electron transfer half-reaction entropies, ΔSºET, in aprotic solvents. ΔSºET and

  12. Options for nitriles removal from C{sub 4}-C{sub 5} cuts. 3. Catalytic hydrogenation using the swing reactive removal process

    Energy Technology Data Exchange (ETDEWEB)

    Ramirez-Corredores, M.M.; Hernandez, Z.; Guerra, J.; Alvarez, R.; Medina, J. [PDVSA Intevep, Refinacion y Petroquimica, Aptdo. 76343, Caracas 1070A (Venezuela)

    2003-05-15

    C{sub 4} and C{sub 5} cuts from FCC units can be useful in the preparation of oxygenates such as MTBE, ETBE, and TAME. However, these feedstocks typically contain nitriles and diolefins which poison the etherification catalyst. Albeit, in USA, strong concerns on oxygenate uses have given rise to prohibition within certain states, those concerns have not derived into such drastic decisions in Europe. Still, removing nitriles from reactive feedstocks or converting them into value-added products might be of interest. PDVSA Intevep has developed several methods for removing nitriles present in those feedstocks, which include one based on adsorption [M.M. Ramirez-Corredores, Z. Hernandez, J. Guerra, J. Medina, R. Alvarez. Submitted to Adsorption.], and two based on catalytic conversion. In the first part of this work [M.M. Ramirez-Corredores, Z. Hernandez, J. Guerra, J. Medina, R. Alvarez. Submitted to Adsorption.], both the adsorbent and the adsorption process were described. The details of the catalytic system for the simultaneous hydrogenation of nitriles and diolefins were given in the second part [M.M. Ramirez-Corredores, T. Romero, D. Djaouadi, Z. Hernandez, J. Guerra. Submitted to Ind. Eng. Chem. Res.]. The main features of the catalyst include its nitrile adsorption capabilities, the specific oxidation state of the metal active phase, and the strong early deactivation. In this work, we discuss the convenience of converting the nitriles and diolefins by using a swing mode of reaction between two (or more) reacting zones in order to overcome the drawbacks of the observed deactivation.

  13. Photoelectron spectroscopy investigation of the temperature-induced deprotonation and substrate-mediated hydrogen transfer in a hydroxyphenyl-substituted porphyrin

    Energy Technology Data Exchange (ETDEWEB)

    Smykalla, Lars, E-mail: lars.smykalla@physik.tu-chemnitz.de [Technische Universität Chemnitz, Institute of Physics, Solid Surfaces Analysis Group, D-09107 Chemnitz (Germany); Shukrynau, Pavel [Technische Universität Chemnitz, Institute of Physics, Solid Surfaces Analysis Group, D-09107 Chemnitz (Germany); Mende, Carola; Lang, Heinrich [Technische Universität Chemnitz, Institute of Chemistry, Inorganic Chemistry, D-09107 Chemnitz (Germany); Knupfer, Martin [Electronic and Optical Properties Department, IFW Dresden, D-01171 Dresden (Germany); Hietschold, Michael [Technische Universität Chemnitz, Institute of Physics, Solid Surfaces Analysis Group, D-09107 Chemnitz (Germany)

    2015-04-01

    Highlights: • Photoelectron spectroscopy of tetra(p-hydroxyphenyl)porphyrin on Au(1 1 1) and Ag(1 1 0). • Ratio of amount of −NH− to −N= in the molecule on Au(1 1 1) decreases after annealing. • Dissociation of −OH groups and transfer of hydrogen atoms to −N= on Ag(1 1 0). • Cleavage of C−H bonds of porphyrin macro-cycle at high temperature. • Changes of the valence band of the molecule in dependance of annealing temperature. - Abstract: The temperature dependent stepwise deprotonation of 5,10,15,20-tetra(p-hydroxyphenyl)-porphyrin is investigated using photoelectron spectroscopy. An abundance of pyrrolic relative to iminic nitrogen and a decrease in the ratio of the amount of −NH− to −N= with increasing annealing temperature is found. In contrast to the molecules adsorbed on Au(1 1 1), on the more reactive Ag(1 1 0) surface, partial dissociation of the hydroxyl groups and subsequent diffusion and rebonding of hydrogen to the central nitrogen atoms resulting in a zwitterionic molecule was clearly observed. Moreover, partial C−H bond cleavage and the formation of new covalent bonds with adjacent molecules or the surface starts at a relatively high annealing temperature of 300 °C. This reaction is identified to occur at the carbon atoms of the pyrrole rings, which leads also to a shift in the N 1s signal and changes in the valence band of the molecules. Our results show that annealing can significantly alter the molecules which were deposited depending on the maximum temperature and the catalytic properties of the specific substrate. The thermal stability should be considered if a molecular monolayer is prepared from a multilayer by desorption, or if annealing is applied to enhance the self-assembly of molecular structures.

  14. Photoelectron spectroscopy investigation of the temperature-induced deprotonation and substrate-mediated hydrogen transfer in a hydroxyphenyl-substituted porphyrin

    International Nuclear Information System (INIS)

    Highlights: • Photoelectron spectroscopy of tetra(p-hydroxyphenyl)porphyrin on Au(1 1 1) and Ag(1 1 0). • Ratio of amount of −NH− to −N= in the molecule on Au(1 1 1) decreases after annealing. • Dissociation of −OH groups and transfer of hydrogen atoms to −N= on Ag(1 1 0). • Cleavage of C−H bonds of porphyrin macro-cycle at high temperature. • Changes of the valence band of the molecule in dependance of annealing temperature. - Abstract: The temperature dependent stepwise deprotonation of 5,10,15,20-tetra(p-hydroxyphenyl)-porphyrin is investigated using photoelectron spectroscopy. An abundance of pyrrolic relative to iminic nitrogen and a decrease in the ratio of the amount of −NH− to −N= with increasing annealing temperature is found. In contrast to the molecules adsorbed on Au(1 1 1), on the more reactive Ag(1 1 0) surface, partial dissociation of the hydroxyl groups and subsequent diffusion and rebonding of hydrogen to the central nitrogen atoms resulting in a zwitterionic molecule was clearly observed. Moreover, partial C−H bond cleavage and the formation of new covalent bonds with adjacent molecules or the surface starts at a relatively high annealing temperature of 300 °C. This reaction is identified to occur at the carbon atoms of the pyrrole rings, which leads also to a shift in the N 1s signal and changes in the valence band of the molecules. Our results show that annealing can significantly alter the molecules which were deposited depending on the maximum temperature and the catalytic properties of the specific substrate. The thermal stability should be considered if a molecular monolayer is prepared from a multilayer by desorption, or if annealing is applied to enhance the self-assembly of molecular structures

  15. Influence of preparation method on supported Cu-Ni alloys and their catalytic properties in high pressure CO hydrogenation

    DEFF Research Database (Denmark)

    Wu, Qiongxiao; Eriksen, Winnie L.; Duchstein, Linus Daniel Leonhard;

    2014-01-01

    (50 bar CO and 50 bar H2). These alloy catalysts are highly selective (more than 99 mol%) and active for methanol synthesis; however, loss of Ni caused by nickel carbonyl formation is found to be a serious issue. The Ni carbonyl formation should be considered, if Ni-containing catalysts (even in...... impregnation, the coprecipitation and deposition-coprecipitation methods are more efficient for preparation of small and homogeneous Cu-Ni alloy nanoparticles. In order to examine the stability of Cu-Ni alloys in high pressure synthesis gas conversion, they have been tested for high pressure CO hydrogenation...

  16. Green diesel production via catalytic hydrogenation/decarboxylation of triglycerides and fatty acids of vegetable oil and brown grease

    Science.gov (United States)

    Sari, Elvan

    Increase in the petroleum prices, projected increases in the world's energy demand and environmental awareness have shifted the research interest to the alternative fuel technologies. In particular, green diesel, vegetable oil/animal fat/waste oil and grease derived hydrocarbons in diesel boiling range, has become an attractive alternative to biodiesel---a mixture of fatty acid methyl esters, particularly due to its superior fuel properties that are similar to petroleum diesel. Hence, green diesel can be used as a drop-in fuel in the current diesel engines. The current technology for production of green diesel-hydrodeoxygenation of triglycerides and fatty acids over conventional hydrotreating catalysts suffers from fast catalyst deactivation in the absence of hydrogen combined with high temperatures and high fatty acid content in the feedstock. Additionally, excess hydrogen requirement for hydrodeoxygenation technique leads to high production costs. This thesis proposes a new technology-selective decarboxylation of brown grease, which is a mixture of fats and oils collected from waste water trap and rich in fatty acids, over a supported noble metal catalyst that overcomes the green diesel production challenges. In contrast to other feedstocks used for liquid biofuel production, brown grease is inexpensive and non-food competing feedstock, therefore the process finds solution to waste management issues, reduces the renewable fuel production cost and does not add to the global food shortage problems. Special catalyst formulations were developed to have a high activity and stability in the absence of hydrogen in the fatty acid decarboxylation process. The study shows how catalyst innovations can lead to a new technology that overcomes the process challenges. First, the effect of reaction parameters on the activity and the selectivity of brown grease decarboxylation with minimum hydrogen consumption over an activated carbon supported palladium catalyst were

  17. How Formaldehyde Inhibits Hydrogen Evolution by [FeFe]-Hydrogenases: Determination by ¹³C ENDOR of Direct Fe-C Coordination and Order of Electron and Proton Transfers.

    Science.gov (United States)

    Bachmeier, Andreas; Esselborn, Julian; Hexter, Suzannah V; Krämer, Tobias; Klein, Kathrin; Happe, Thomas; McGrady, John E; Myers, William K; Armstrong, Fraser A

    2015-04-29

    Formaldehyde (HCHO), a strong electrophile and a rapid and reversible inhibitor of hydrogen production by [FeFe]-hydrogenases, is used to identify the point in the catalytic cycle at which a highly reactive metal-hydrido species is formed. Investigations of the reaction of Chlamydomonas reinhardtii [FeFe]-hydrogenase with formaldehyde using pulsed-EPR techniques including electron-nuclear double resonance spectroscopy establish that formaldehyde binds close to the active site. Density functional theory calculations support an inhibited super-reduced state having a short Fe-(13)C bond in the 2Fe subsite. The adduct forms when HCHO is available to compete with H(+) transfer to a vacant, nucleophilic Fe site: had H(+) transfer already occurred, the reaction of HCHO with the Fe-hydrido species would lead to methanol, release of which is not detected. Instead, Fe-bound formaldehyde is a metal-hydrido mimic, a locked, inhibited form analogous to that in which two electrons and only one proton have transferred to the H-cluster. The results provide strong support for a mechanism in which the fastest pathway for H2 evolution involves two consecutive proton transfer steps to the H-cluster following transfer of a second electron to the active site. PMID:25871921

  18. Combined dehydration/(transfer)-hydrogenation of C6-sugars (D-glucose and D-fructose) to gamma-valerolactone using ruthenium catalysts

    OpenAIRE

    Heeres, Hans; Handana, Ratna; Chunai, Dai; Rasrendra, Carolus Borromeus; Girisuta, Buana; Heeres, Hero Jan

    2009-01-01

    gamma-Valerolactone (GVL) is considered a very interesting green, bio-based platform chemical with high application potential. We here describe research activities on the one-pot catalytic synthesis of GVL from C6-sugar sources (D-glucose, D-fructose, sucrose and cellulose) using an acid catalyst in combination with a hydrogenation catalyst (Ru/C) and either molecular hydrogen or formic acid as the hydrogen donor. When using formic acid, the highest yield of GVL (52 mol%) was obtained at 180 ...

  19. Catalytic hydrothermal gasification of algae for hydrogen production: composition of reaction products and potential for nutrient recycling.

    Science.gov (United States)

    Onwudili, Jude A; Lea-Langton, Amanda R; Ross, Andrew B; Williams, Paul T

    2013-01-01

    Chlorella vulgaris, Spirulina platensis and Saccharina latissima were processed under supercritical water gasification conditions at 500 °C, 36 MPa in an Inconel batch reactor for 30 min in the presence/absence of NaOH and/or Ni-Al(2)O(3). Hydrogen gas yields were more than two times higher in the presence of NaOH than in its absence and tar yields were reduced by up to 71%. Saccharina, a carbohydrate-rich macro-alga, gave the highest hydrogen gas yields of 15.1 mol/kg. The tars from all three algae contained aromatic compounds, including phenols, alkyl benzenes and polycyclic aromatic hydrocarbons as well as heterocyclic nitrogen compounds. Tars from Chlorella and Spirulina contained high yields of pyridines, pyrroles, indoles and pyrimidines. Up to 97% TOC removal were achieved in the process waters from the gasification of the algae. Analyses for specific nutrients in the process waters indicated that the process waters from Saccharina could potentially be used for microalgae cultivation. PMID:23131625

  20. Valorization of Waste Lipids through Hydrothermal Catalytic Conversion to Liquid Hydrocarbon Fuels with in Situ Hydrogen Production

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Dongwook; Vardon, Derek R.; Murali, Dheeptha; Sharma, Brajendra K.; Strathmann, Timothy J.

    2016-03-07

    We demonstrate hydrothermal (300 degrees C, 10 MPa) catalytic conversion of real waste lipids (e.g., waste vegetable oil, sewer trap grease) to liquid hydrocarbon fuels without net need for external chemical inputs (e.g., H2 gas, methanol). A supported bimetallic catalyst (Pt-Re/C; 5 wt % of each metal) previously shown to catalyze both aqueous phase reforming of glycerol (a triacylglyceride lipid hydrolysis coproduct) to H2 gas and conversion of oleic and stearic acid, model unsaturated and saturated fatty acids, to linear alkanes was applied to process real waste lipid feedstocks in water. For reactions conducted with an initially inert headspace gas (N2), waste vegetable oil (WVO) was fully converted into linear hydrocarbons (C15-C17) and other hydrolyzed byproducts within 4.5 h, and H2 gas production was observed. Addition of H2 to the initial reactor headspace accelerated conversion, but net H2 production was still observed, in agreement with results obtained for aqueous mixtures containing model fatty acids and glycerol. Conversion to liquid hydrocarbons with net H2 production was also observed for a range of other waste lipid feedstocks (animal fat residuals, sewer trap grease, dry distiller's grain oil, coffee oil residual). These findings demonstrate potential for valorization of waste lipids through conversion to hydrocarbons that are more compatible with current petroleum-based liquid fuels than the biodiesel and biogas products of conventional waste lipid processing technologies.

  1. Engineered materials as potential geocatalysts in deep geological nuclear waste repositories: A case study of the stainless steel catalytic effect on nitrate reduction by hydrogen

    International Nuclear Information System (INIS)

    Highlights: • We demonstrate that stainless steels (316L and Hastelloy) can catalyse nitrate reduction in the presence of hydrogen. • Hydrogen is the sole electron donor. • The reaction proceeds via nitrate sorption at the steel surface up to pH = 9 following Langmuir–Hinshelwood mechanism. • The reaction is inhibited by the presence of phosphate anions which compete with nitrate for the steel sorption sites. - Abstract: The reduction of NO3- in natural waters is commonly promoted by biological activity. In the context of deep geological nuclear waste repositories with potentially high H2 pressure, abiotic redox reactions may be envisaged. Here, the catalytic effect of “inert” metallic surfaces, in part used for nuclear waste canisters, on NO3- reduction under H2 pressure is evaluated. The study is focused on stainless steels by testing the 316L and Hastelloy C276 steels. A parametric kinetic study (0 < P(H2) < 10 bar, 0.1 < [NO3-] < 10 mM, 90 < T° < 150 °C, 4 < pHin situ < 9) reveals that NO3- reduction, in the presence of stainless steel 316L and Hastelloy C276, proceeds via a pH-independent reaction requiring H2 as an electron donor. No corrosion of these steels is observed indicating a true catalytic process. The reaction is inhibited in the presence of PO43-. Activation energies assuming a first-order reaction in the 90–150 °C temperature range are found to be 46 kJ/mol for stainless steel 316L and 186 kJ/mol for Hastelloy C276, making the reaction efficient at lower temperature and on a human time scale. Nitrate sorption at the metallic surface being thought to be the limiting step, sorption and competitive sorption isotherms of several oxyanions were performed at 90 °C on 316L. Nitrate and PO43- are more strongly sorbed than SO42-, likely as inner sphere complexes, and in a large pH range, from acidic to pH 9. The Langmuir–Hinshelwood formalism best fits the kinetic data. The nature of the surface complex, and the competition for

  2. Height determination at the transfer unit in isotopic distillation of hydrogen on type B7 ordered column packing

    International Nuclear Information System (INIS)

    Owing to the low pressure drop implied by ordered column packings these are often utilized for vacuum distillations and separation of mixtures in which the important component occurs at a very low concentration, as for instance is the case of water, deuterium or oxygen isotopic distillation. The paper presents a model for determination of the height of transfer unit (HTU) in the hydrogen isotopic distillation installation, equipped with ordered column packing of B7 type. The computed values for HUT based on the analogy between heat, moment and mass transfer, were compared with the experimental data

  3. Monomeric Cu(Ⅱ) Complex Containing Chiral Phase-transfer Catalyst as Ligand and Its Asymmetrically Catalytic Reaction

    Institute of Scientific and Technical Information of China (English)

    QU Zhi-Rong; XIONG Ren-Gen

    2008-01-01

    The thermal treatment of CuCl2 with N-(4'-vinylbenzyl)cinchonidinitim chloride(L1)afforded a monomeric discrete homochiral copper(Ⅱ)complex N-4'-(vinylbenzyl)cinchonidinium trichlorocoprate(Ⅱ)(1).Their applications to the enantioselectively catalytic alkylation reaction of N-(diphenylmethylidene)glycine tert-butyl ester(3)show that the higher ee value observed in catalyst 1 than that in the corresponding free ligand L1 is probably due to the rigidity enhancement after the coordination of N atom of quinoline ring to the copper ion.

  4. Charge density analysis of two proton transfer complexes: Understanding hydrogen bonding and determination of in-crystal dipole moments

    Indian Academy of Sciences (India)

    Reji Thomas; Shrinwantu Pal; Ayan Datta; Mariusz K Marchewka; Henryk Ratajczak; Swapan K Pati; G U Kulkarni

    2008-11-01

    An experimental charge density study has been carried out on proton-transfer complexes exhibiting nonlinear optical (NLO) properties-melaminium tartrate monohydrate and L-asparaginium picrate employing high-resolution X-ray diffraction at 100 K. Both the complexes crystallize in non-centric space group P21 and the structures exhibit interesting patterns of N-H…O and O-H…O hydrogen bonding. Experimental determination of the dipole moment () for the asymmetric unit reveals that for both the crystals, there is a large cooperative enhancement in the crystalline arising essentially due to hydrogen bond mediated charge transfer between the melaminium ion and the L-tartrate in one case, between the Lasparaginium ion and the picrate in the other complex. We have additionally performed theoretical calculations at the density functional theory (DFT) level to understand the origin of enhancement of the dipole moments in the two systems.

  5. Synthesis, crystal structure, and charge-transfer complexes of TTF derivatives having two imidazole hydrogen-bonding units

    International Nuclear Information System (INIS)

    New hydrogen-bond functionalized tetrathiafulvalene (TTF) derivatives (1 and 2) having two imidazole moieties, which are attached to TTF at the 2- and 4-positions in the imidazole ring, respectively, were synthesized. Electrochemical measurements indicated that the introduction of imidazole moieties at 2- or 4-positions slightly reduced or enhanced the electron-donating ability of TTF. In the crystal structure of 1, N-H...N hydrogen-bonds of the imidazole ring formed a two-dimensional sheet, and further π-stacks on the TTF skeleton built up a one-dimensional column. Mixing 1 with electron-acceptors afforded fully ionic charge-transfer complexes having a 1:1 donor-acceptor ratio, while complex formation of 2 with tetracyanoquinodimethane and p-chloranil yielded partial charge-transfer complexes showing semiconducting behaviors (room temperature conductivities=10-3-10-2 S cm-1).

  6. Stepwise vs concerted excited state tautomerization of 2-hydroxypyridine: Ammonia dimer wire mediated hydrogen/proton transfer

    International Nuclear Information System (INIS)

    The stepwise and concerted excited state intermolecular proton transfer (PT) and hydrogen transfer (HT) reactions in 2-hydroxypyridine-(NH3)2 complex in the gas phase under Cs symmetry constraint and without any symmetry constraints were performed using quantum chemical calculations. It shows that upon excitation, the hydrogen bonded in 2HP-(NH3)2 cluster facilitates the releasing of both hydrogen and proton transfer reactions along ammonia wire leading to the formation of the 2-pyridone tautomer. For the stepwise mechanism, it has been found that the proton and the hydrogen may transfer consecutively. These processes are distinguished from each other through charge translocation analysis and the coupling between the motion of the proton and the electron density distribution along ammonia wire. For the complex under Cs symmetry, the excited state HT occurs on the A″(1πσ∗) and A′(1nσ∗) states over two accessible energy barriers along reaction coordinates, and excited state PT proceeds mainly through the A′(1ππ∗) and A″(1nπ∗) potential energy surfaces. For the unconstrained complex, potential energy profiles show two 1ππ∗-1πσ∗ conical intersections along enol → keto reaction path indicating that proton and H atom are localized, respectively, on the first and second ammonia of the wire. Moreover, the concerted excited state PT is competitive to take place with the stepwise process, because it proceeds over low barriers of 0.14 eV and 0.11 eV with respect to the Franck-Condon excitation of enol tautomer, respectively, under Cs symmetry and without any symmetry constraints. These barriers can be probably overcome through tunneling effect

  7. Stepwise vs concerted excited state tautomerization of 2-hydroxypyridine: Ammonia dimer wire mediated hydrogen/proton transfer

    Energy Technology Data Exchange (ETDEWEB)

    Esboui, Mounir, E-mail: mounir.esboui@fst.rnu.tn [Laboratoire de Spectroscopie Atomique, Moléculaire et Applications, Département de Physique, Faculté des Sciences de Tunis, 2092 Tunis (Tunisia); Technical and Vocational Training Corporation, Hail College of Technology, P.O. Box 1960, Hail 81441 (Saudi Arabia)

    2015-07-21

    The stepwise and concerted excited state intermolecular proton transfer (PT) and hydrogen transfer (HT) reactions in 2-hydroxypyridine-(NH{sub 3}){sub 2} complex in the gas phase under Cs symmetry constraint and without any symmetry constraints were performed using quantum chemical calculations. It shows that upon excitation, the hydrogen bonded in 2HP-(NH{sub 3}){sub 2} cluster facilitates the releasing of both hydrogen and proton transfer reactions along ammonia wire leading to the formation of the 2-pyridone tautomer. For the stepwise mechanism, it has been found that the proton and the hydrogen may transfer consecutively. These processes are distinguished from each other through charge translocation analysis and the coupling between the motion of the proton and the electron density distribution along ammonia wire. For the complex under Cs symmetry, the excited state HT occurs on the A″({sup 1}πσ{sup ∗}) and A′({sup 1}nσ{sup ∗}) states over two accessible energy barriers along reaction coordinates, and excited state PT proceeds mainly through the A′({sup 1}ππ{sup ∗}) and A″({sup 1}nπ{sup ∗}) potential energy surfaces. For the unconstrained complex, potential energy profiles show two {sup 1}ππ{sup ∗}-{sup 1}πσ{sup ∗} conical intersections along enol → keto reaction path indicating that proton and H atom are localized, respectively, on the first and second ammonia of the wire. Moreover, the concerted excited state PT is competitive to take place with the stepwise process, because it proceeds over low barriers of 0.14 eV and 0.11 eV with respect to the Franck-Condon excitation of enol tautomer, respectively, under Cs symmetry and without any symmetry constraints. These barriers can be probably overcome through tunneling effect.

  8. Bipolar Carrier Transfer Channels in Epitaxial Graphene/SiC Core-Shell Heterojunction for Efficient Photocatalytic Hydrogen Evolution.

    Science.gov (United States)

    Lu, Wei; Wang, Da; Guo, Liwei; Jia, Yuping; Ye, Manping; Huang, Jiao; Li, Zhilin; Peng, Yuan; Yuan, Wenxia; Chen, Xiaolong

    2015-12-22

    Bipolar carrier transfer channels exist in the in situ epitaxial-graphene-wrapped 6H-SiC core-shell heterojunction due to the self-doping of graphene. Due to the special interface structure and high graphene quality, this material exhibits significant photocatalytic enhancement. Its hydrogen evolution efficiency is greater than that of the Pt/SiC composite. This micrometer-sized metal-free photocatalyst exhibits an activity comparable to that of metal-based nanophotocatalysts. PMID:26541083

  9. Formation, Isolation and Characterization of a New Ruthenium Complex in Reaction of Acetone Masked Terminal Alkynone with Transfer Hydrogenation Catalyst

    Institute of Scientific and Technical Information of China (English)

    郭敏捷; 李到; 孙延辉; 成江; 张兆国

    2004-01-01

    Reaction of [1S,2S-(Ts-diphen)Ru(Ⅱ)(p-cymene)] (1S,2S-Ts-diphen= 1S,2S-N-tosyl-1,2-diphenylethylenediamine) and 2-hydroxy-2-methyl-non-3-yn-5-one under transfer hydrogenation condition gave a ruthenium complex bearing a 2,5-dihydrofuran moiety. The complex was characterized and a possible mechanism for the formation of the complex was proposed.

  10. Simulation Studies of the Hydrogen Production from Methanol Partial Oxidation Steam Reforming by a Tubular Packed-bed Catalytic Reactor

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    Hydrogen production by partial oxidation steam reforming of methanol over a Cu/ZnO/Al2 O3 cata lyst has been paid more and more attention. The chemical equilibria involved in the methanol partial oxidation steam reforming reaction network such as methanol partial oxidation, methanol steam reforming, decomposition of methanol and water-gas shift reaction have been examined over the ranges of temperature 473-1073 K under normal pressure. Based on the detailed kinetics of these reactions over a Cu/ZnO/Al2O3 catalyst, and from the basic concept of the effectiveness factor, the intraparticle diffusion limitations were taken into account. The effec tiveness factors for each reaction along the bed length were calculated. Then important results were offered for the simulation of this reaction process.

  11. Ultrathin Coating of Confined Pt Nanocatalysts by Atomic Layer Deposition for Enhanced Catalytic Performance in Hydrogenation Reactions.

    Science.gov (United States)

    Wang, Meihua; Gao, Zhe; Zhang, Bin; Yang, Huimin; Qiao, Yan; Chen, Shuai; Ge, Huibin; Zhang, Jiankang; Qin, Yong

    2016-06-13

    Metal-support interfaces play a prominent role in heterogeneous catalysis. However, tailoring the metal-support interfaces to realize full utilization remains a major challenge. In this work, we propose a graceful strategy to maximize the metal-oxide interfaces by coating confined nanoparticles with an ultrathin oxide layer. This is achieved by sequential deposition of ultrathin Al2 O3 coats, Pt, and a thick Al2 O3 layer on carbon nanocoils templates by atomic layer deposition (ALD), followed by removal of the templates. Compared with the Pt catalysts confined in Al2 O3 nanotubes without the ultrathin coats, the ultrathin coated samples have larger Pt-Al2 O3 interfaces. The maximized interfaces significantly improve the activity and the protecting Al2 O3 nanotubes retain the stability for hydrogenation reactions of 4-nitrophenol. We believe that applying ALD ultrathin coats on confined catalysts is a promising way to achieve enhanced performance for other catalysts. PMID:27061428

  12. Scanning electrochemical microscopy: surface interrogation of adsorbed hydrogen and the open circuit catalytic decomposition of formic acid at platinum.

    Science.gov (United States)

    Rodríguez-López, Joaquín; Bard, Allen J

    2010-04-14

    The surface interrogation mode of scanning electrochemical microscopy (SECM) is extended to the in situ quantification of adsorbed hydrogen, H(ads), at polycrystalline platinum. The methodology consists of the production, at an interrogator electrode, of an oxidized species that is able to react with H(ads) on the Pt surface and report the amounts of this adsorbate through the SECM feedback response. The technique is validated by comparison to the electrochemical underpotential deposition (UPD) of hydrogen on Pt. We include an evaluation of electrochemical mediators for their use as oxidizing reporters for adsorbed species at platinum; a notable finding is the ability of tetramethyl-p-phenylenediamine (TMPD) to oxidize (interrogate) H(ads) on Pt at low pH (0.5 M H(2)SO(4) or 1 M HClO(4)) and with minimal background effects. As a case study, the decomposition of formic acid (HCOOH) in acidic media at open circuit on Pt was investigated. Our results suggest that formic acid decomposes at the surface of unbiased Pt through a dehydrogenation route to yield H(ads) at the Pt surface. The amount of H(ads) depended on the open circuit potential (OCP) of the Pt electrode at the time of interrogation; at a fixed concentration of HCOOH, a more negative OCP yielded larger amounts of H(ads) until reaching a coulomb limiting coverage close to 1 UPD monolayer of H(ads). The introduction of oxygen into the cell shifted the OCP to more positive potentials and reduced the quantified H(ads); furthermore, the system was shown to be chemically reversible, as several interrogations could be run consecutively and reproducibly regardless of the path taken to reach a given OCP. PMID:20225806

  13. Investigations on the role of proton-coupled electron transfer in hydrogen activation by [FeFe]-hydrogenase.

    Science.gov (United States)

    Mulder, David W; Ratzloff, Michael W; Bruschi, Maurizio; Greco, Claudio; Koonce, Evangeline; Peters, John W; King, Paul W

    2014-10-29

    Proton-coupled electron transfer (PCET) is a fundamental process at the core of oxidation-reduction reactions for energy conversion. The [FeFe]-hydrogenases catalyze the reversible activation of molecular H2 through a unique metallocofactor, the H-cluster, which is finely tuned by the surrounding protein environment to undergo fast PCET transitions. The correlation of electronic and structural transitions at the H-cluster with proton-transfer (PT) steps has not been well-resolved experimentally. Here, we explore how modification of the conserved PT network via a Cys → Ser substitution at position 169 proximal to the H-cluster of Chlamydomonas reinhardtii [FeFe]-hydrogenase (CrHydA1) affects the H-cluster using electron paramagnetic resonance (EPR) and Fourier transform infrared (FTIR) spectroscopy. Despite a substantial decrease in catalytic activity, the EPR and FTIR spectra reveal different H-cluster catalytic states under reducing and oxidizing conditions. Under H2 or sodium dithionite reductive treatments, the EPR spectra show signals that are consistent with a reduced [4Fe-4S]H(+) subcluster. The FTIR spectra showed upshifts of νCO modes to energies that are consistent with an increase in oxidation state of the [2Fe]H subcluster, which was corroborated by DFT analysis. In contrast to the case for wild-type CrHydA1, spectra associated with Hred and Hsred states are less populated in the Cys → Ser variant, demonstrating that the exchange of -SH with -OH alters how the H-cluster equilibrates among different reduced states of the catalytic cycle under steady-state conditions. PMID:25286239

  14. Hydrogen production with short contact time. Catalytic partial oxidation of hydrocarbons and oxygenated compounds: Recent advances in pilot- and bench-scale testing and process design

    Energy Technology Data Exchange (ETDEWEB)

    Guarinoni, A.; Ponzo, R.; Basini, L. [ENI Refining and Marketing Div., San Donato Milanese (Italy)

    2010-12-30

    ENI R and D has been active for fifteen years in the development of Short Contact Time - Catalytic Partial Oxidation (SCT-CPO) technologies for producing Hydrogen/Synthesis Gas. From the beginning the experimental work addressed either at defining the fundamental principles or the technical and economical potential of the technology. Good experimental responses, technical solutions' simplicity and flexibility, favourable techno-economical evaluations promoted the progressive widening of the field of the investigations. From Natural Gas (NG) the range of ''processable'' Hydrocarbons extended to Liquefied Petroleum Gas (LPG) and Gasoils, including those characterised by high levels of unsaturated and sulphurated molecules and, lately, to other compounds with biological origin. The extensive work led to the definition of different technological solutions, grouped as follows: Technology 1: Air Blown SCT-CPO of Gaseous Hydrocarbons and/or Light Compounds with biological origin Technology 2: Enriched Air/Oxygen Blown SCT-CPO of Gaseous Hydrocarbons and/or Light Compounds with biological origin Technology 3: Enriched Air/Oxygen Blown SCT-CPO of Liquid Hydrocarbons and/or Compounds with biological origin Recently, the licence rights on a non-exclusive basis for the commercialisation of SCT-CPO based processes for H{sub 2}/Synthesis gas production from light hydrocarbons with production capacity lower than 5,000 Nm{sup 3}/h of H{sub 2} or 7,500 Nm3/h of syngas have been assigned to two external companies. In parallel, development of medium- and large-scale plant solutions is progressing within the ENI group framework. These last activities are addressed to the utilisation of SCT-CPO for matching the variable Hydrogen demand in several contexts of oil refining operation. This paper will report on the current status of SCT-CPO with a focus on experimental results obtained, either at pilot- and bench- scale level. (orig.)

  15. Effect of hydrogen on passivation quality of SiNx/Si-rich SiNx stacked layers deposited by catalytic chemical vapor deposition on c-Si wafers

    International Nuclear Information System (INIS)

    We investigate the role of hydrogen content and fixed charges of catalytic chemical vapor deposited (Cat-CVD) SiNx/Si-rich SiNx stacked layers on the quality of crystalline silicon (c-Si) surface passivation. Calculated density of fixed charges is on the order of 1012 cm−2, which is high enough for effective field effect passivation. Hydrogen content in the films is also found to contribute significantly to improvement in passivation quality of the stacked layers. Furthermore, Si-rich SiNx films deposited with H2 dilution show better passivation quality of SiNx/Si-rich SiNx stacked layers than those prepared without H2 dilution. Effective minority carrier lifetime (τeff) in c-Si passivated by SiNx/Si-rich SiNx stacked layers is as high as 5.1 ms when H2 is added during Si-rich SiNx deposition, which is much higher than the case of using Si-rich SiNx films prepared without H2 dilution showing τeff of 3.3 ms. - Highlights: • Passivation mechanism of Si-rich SiNx/SiNx stacked layers is investigated. • H atoms play important role in passivation quality of the stacked layer. • Addition of H2 gas during Si-rich SiNx film deposition greatly enhances effective minority carrier lifetime (τeff). • For a Si-rich SiNx film with refractive index of 2.92, τeff improves from 3.3 to 5.1 ms by H2 addition

  16. Heterogeneous kinetic modeling of the catalytic conversion of cycloparaffins

    Science.gov (United States)

    Al-Sabawi, Mustafa N.

    The limited availability of high value light hydrocarbon feedstocks along with the rise in crude prices has resulted in the international recognition of the vast potential of Canada's oil sands. With the recent expansion of Canadian bitumen production come, however, many technical challenges, one of which is the significant presence of aromatics and cycloparaffins in bitumen-derived feedstocks. In addition to their negative environmental impact, aromatics limit fluid catalytic cracking (FCC) feedstock conversion, decrease the yield and quality of valuable products such as gasoline and middle distillates, increase levels of polyaromatic hydrocarbons prone to form coke on the catalyst, and ultimately compromise the FCC unit performance. Although cycloparaffins do not have such negative impacts, they are precursors of aromatics as they frequently undergo hydrogen transfer reactions. However, cycloparaffin cracking chemistry involves other competing reactions that are complex and need much investigation. This dissertation provides insights and understanding of the fundamentals of the catalytic cracking of cycloparaffins using carefully selected model compounds such as methylcyclohexane (MCH) and decalin. Thermal and catalytic cracking of these cycloparaffins on FCC-type catalysts are carried out using the CREC Riser Simulator under operating conditions similar to those of the industrial FCC units in terms of temperature, reaction time, reactant partial pressure and catalyst-to-hydrocarbon ratio. The crystallite size of the supported zeolites is varied between 0.4 and 0.9 microns, with both activity and selectivity being monitored. Catalytic conversions ranged between 4 to 16 wt% for MCH and between 8 to 27 wt% for decalin. Reaction pathways of cycloparaffins are determined, and these include ring-opening, protolytic cracking, isomerization, hydrogen transfer and transalkylation. The yields and selectivities of over 60 and 140 products, formed during MCH and decalin

  17. Magnetic gold nanocatalyst (nanocat-Fe–Au): catalytic applications for the oxidative esterification and hydrogen transfer reactions

    Science.gov (United States)

    An efficient and sustainable protocol is described for the oxidative esterification of aldehydes and the reduction of aromatic nitro compounds that uses magnetically separable and reusable maghemite-supported gold nanocatalyst (nanocat-Fe-Au) under mild conditions. The complex ch...

  18. Elucidation of coal liquefaction mechanism by the use of tritium and 35S tracer methods. Effects of pyrrhotite and sulfur on hydrogen transfer in coal liquefaction

    International Nuclear Information System (INIS)

    Effects of addition of the catalyst (pyrrhotite) and sulfur on hydrogen transfer in liquefaction of Taiheiyo coal were investigated using tritium and 35S. The coal liquefaction was performed at the initial pressure of 5.9 MPa and at 400degC for 30 min with tetralin solvent and tritium-labelled hydrogen, with or without the synthesized pyrrhotite catalyst and sulfur (or 35S-labelled sulfur). The specific activities of tritium and 35S in the reaction products were measured with a liquid scintillation counter. Amounts of exchanged and transferred hydrogens between the gas phase and coal/solvent, were calculated from the distributions of tritium and changes in the composition of products. In the reaction with tritiated hydrogen and solvent, the dehydrogenation of tetralin to produce naphthalene and the hydrogen exchange reaction between gas phase and solvent were promoted by added catalyst and sulfur. Added sulfur produced hydrogen sulfide mainly with hydrogen of solvent. A part of added sulfur participated in the sulfur exchange reaction with the pyrrhotite catalyst. In the reaction with tritiated hydrogen, solvent and coal, the hydrogen addition and exchange to coal and liquefaction products increased with the addition of catalyst and sulfur. It was suggested the sulfur promoted the formation of tetralyl radical in the hydrogen transfer from solvent to coal. (author)

  19. Effects of potassium on Ni-K/Al2O3 catalysts in the synthesis of carbon nanofibers by catalytic hydrogenation of CO2.

    Science.gov (United States)

    Chen, Ching S; Lin, Jarrn H; You, Jiann H; Yang, Kuo H

    2010-03-25

    Commercially available Ni/Al(2)O(3) samples containing various concentrations of potassium were used to achieve carbon deposition from CO(2) via catalytic hydrogenation. Experimental results show that K additives can induce the formation of carbon nanofibers or carbon deposition on Ni/Al(2)O(3) during the reverse water-gas shift reaction. This work proposes that the formation rate of carbon deposition depends closely on ensemble control, suggesting that the ensemble size necessary to form carbon may be approximately 0.5 potassium atoms. The results of CO(2) temperature-programmed desorption provide strong evidence that the new adsorption sites for CO(2) created on Ni-K/Al(2)O(3) closely depend upon the synthesis of carbon nanofibers. It is found that some potassium-related active phases obtained by calcination and reduction pretreatments can participate in the carbon deposition reaction. The formation pathway for carbon deposition suggests that the main source of carbon deposition is CO(2) and that the pathway is independent of the reaction products CO and CH(4) in the reverse water-gas shift reaction. PMID:19655780

  20. Study of CuZnMOx oxides (M = Al, Zr, Ce, CeZr) for the catalytic hydrogenation of CO2 into methanol

    International Nuclear Information System (INIS)

    CuO-ZnO-Al2O3 catalysts were synthesized by two methods, sol-gel and co-precipitation syntheses. Al2O3 was then substituted with other supports, such as ZrO2, CeO2 and CeO2-ZrO2 in order to have a better understanding of the support's effect. These catalysts containing 30 wt% of Cu were then tested for CO2 hydrogenation into methanol. The effect of reaction temperature and GHSV on the catalytic behaviour was also investigated. The best results were obtained with a 30 CuO-ZnO-ZrO2 catalyst synthesized by coprecipitation and calcined at 400 C. This catalyst presents a good CO2 conversion rate (23%) with 33% of methanol selectivity, leading to a methanol productivity of 331 g(MeOH.kgcata-1.h-1 at 280 C under 50 bar and a GHSV of 10,000 h-1. (authors)

  1. Three-dimensional FeSe2 microflowers assembled by nanosheets: Synthesis, optical properties, and catalytic activity for the hydrogen evolution reaction

    Science.gov (United States)

    Chang, Xiaoying; Jian, Jikang; Cai, Gemei; Wu, Rong; Li, Jin

    2016-03-01

    Three-dimensional FeSe2 microflowers were synthesized for the first time by a facile solvothermal method, using FeCl2·4H2O and selenium powder as raw materials, along with ethanolamine as solvent. The products were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDS), transmission electron microscopy (TEM), and X-ray photoelectron spectroscopy (XPS). The results show that the FeSe2 microflowers consist of nanosheets with a thickness of about 50 - 80 nm. The Raman spectrum shows the characteristic peaks of Se-Se vibration modes. The optical band gap of the sample was determined to be 1.48 eV by UV-visible absorption spectroscopy. The photoluminescence properties of the FeSe2 microflowers and their catalytic activity for the hydrogen evolution reaction were also assessed. Finally, a possible growth mechanism of the FeSe2 microflowers is proposed. [Figure not available: see fulltext.

  2. Production of bio-hydrogenated diesel by catalytic hydrotreating of palm oil over NiMoS2/γ-Al2O3 catalyst.

    Science.gov (United States)

    Srifa, Atthapon; Faungnawakij, Kajornsak; Itthibenchapong, Vorranutch; Viriya-Empikul, Nawin; Charinpanitkul, Tawatchai; Assabumrungrat, Suttichai

    2014-04-01

    Catalytic hydrotreating of palm oil (refined palm olein type) to produce bio-hydrogenated diesel (BHD) was carried out in a continuous-flow fixed-bed reactor over NiMoS2/γ-Al2O3 catalyst. Effects of dominant hydrotreating parameters: temperature: 270-420°C; H2 pressure: 15-80 bar; LHSV: 0.25-5.0 h(-1); and H2/oil ratio: 250-2000 N(cm(3)/cm(3)) on the conversion, product yield, and a contribution of hydrodeoxygenation (HDO) and decarbonylation/decarboxylation (DCO/DCO2) were investigated to find the optimal hydrotreating conditions. All calculations including product yield and the contribution of HDO and DCO/DCO2 were extremely estimated based on mole balance corresponding to the fatty acid composition in feed to fully understand deoxygenation behaviors at different conditions. These analyses demonstrated that HDO, DCO, and DCO2 reactions competitively occurred at each condition, and had different optimal and limiting conditions. The differences in the hydrotreating reactions, liquid product compositions, and gas product composition were also discussed. PMID:24583218

  3. 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...

  4. Heat transfer in pool boiling liquid neon, deuterium and hydrogen, and critical heat flux in forced convection of liquid neon

    International Nuclear Information System (INIS)

    In the first part, free-convection and nucleate pool boiling heat transfer (up to burn-out heat flux) between a platinum wire of 0.15 mm in diameter in neon, deuterium and hydrogen has been studied at atmospheric pressure. These measurements were continued in liquid neon up to 23 bars (Pc ≅ 26.8 b). Film boiling heat transfer coefficients have been measured in pool boiling liquid neon at atmospheric pressure with three heating wires (diameters 0.2, 0.5, 2 mm). All the results have been compared with existing correlations. The second part is devoted to measurements of the critical heat flux limiting heat transfer with small temperature differences between the wall and the liquid neon flowing inside a tube (diameters 3 x 3.5 mm) heated by joule effect on 30 cm of length. Influences of flow stability, nature of electrical current, pressure, mass flow rate and subcooling are shown. In conclusion, the similarity of the heat transfer characteristics in pool boiling as well as in forced convection of liquid neon and hydrogen is emphasized. (author)

  5. Catalytic reduction of U(VI) to U(IV) using hydrogen with platinum loaded on alumina and silica

    International Nuclear Information System (INIS)

    During the reprocessing of spent nuclear fuel, uranium (U) and plutonium (Pu) are together extracted by employing tri-n-butyl phosphate (TBP)/dodecane mixture and their partitioning is achieved by adding uranous nitrate. The partitioning agent, uranous is conventionally produced by the electrolytic reduction of uranyl nitrate. An alternate route for the reduction of U from (VI) to (IV) using hydrogen (H2) as reductant was developed using platinum (Pt) based catalyst. Improvements in the development of the catalyst have been carried out in order to reduce the requirement of Pt without affecting the reduction performance. Experiments using 2 wt% Pt loaded on alumina beads and alumina powder have been performed and results are discussed. As the catalyst supported on alumina was found to be unstable in acidic environment, Pt loaded on silica powder has also been developed. Pt loaded on alumina and silica substrates have been tried to envisage the reduction behaviour using H2 as reductant in presence of hydrazine nitrate which acts as U(IV) stabiliser as well as reductant. Parametric studies have been carried out to optimise the process parameters namely pressure, temperature, U concentration, free acidity, hydrazine concentration and catalyst to U (C/U) ratio. 2 wt% Pt loaded on silica has been selected for further scale up studies for making uranous. (author)

  6. Catalytic effect of nano-sized ScH{sub 2} on the hydrogen storage of mechanically milled MgH{sub 2}

    Energy Technology Data Exchange (ETDEWEB)

    Luo, Xuanli, E-mail: Xuanli.Luo@nottingham.ac.uk; Grant, David M., E-mail: David.Grant@nottingham.ac.uk; Walker, Gavin S., E-mail: Gavin.Walker@nottingham.ac.uk

    2015-02-15

    Highlights: • The ScH{sub 2} nanoparticles improved the MgH{sub 2} dehydrogenation kinetics. • Low activation energy of the dehydrogenation reaction (62 ± 5 kJ mol{sup −1}). • Optimal ScH{sub 2} catalyst content was ca. 12 mol.% to achieve lowest activation energy. • High cycling stability at relatively high temperature up to 450 °C. • The ScH{sub 2} nano-structure remained throughout cycling. - Abstract: The hydrogen storage properties of ball milled xMgH{sub 2}/(1 − x)ScH{sub 2} (x = 0.65-1) samples including capacity, kinetics, thermodynamics and cycling stability, were investigated. The effect of ScH{sub 2} catalyst content and ball milling duration on the kinetics of MgH{sub 2} dehydrogenation were studied. It was found that the optimal content of the catalyst ScH{sub 2} was ca. 12 mol.%, which gave an activation energy (E{sub a}) value of 62 ± 5 kJ mol{sup −1} and a hydrogen storage capacity of 5.8 ± 0.1 wt.% for the sample. There was no loss in kinetics in the ScH{sub 2} catalysed MgH{sub 2} system even after cycling at relatively high temperatures up to 450 °C, and the nano-sized ScH{sub 2} (ca. 70 nm) formed during ball milling remained after (de)hydrogenation cycling. Typical MgH{sub 2} dehydrogenation enthalpy (76 ± 1 kJ mol{sup −1} (H{sub 2})) and entropy (138 ± 2 J mol{sup −1} K{sup −1} (H{sub 2})) values observed by the 0.65MgH{sub 2}/0.35ScH{sub 2} sample demonstrated the effect of ScH{sub 2} was purely a catalytic improvement of the kinetics.

  7. 二氧化碳和甲醇氢等离子体催化反应合成碳酸二甲酯%Hydrogen plasma catalytic synthesis of dimethyl carbonate from carbon dioxide and methanol

    Institute of Scientific and Technical Information of China (English)

    崔艳宏; 王超; 王安杰; 王伟

    2016-01-01

    The Al2O3 supported Cu catalysts were prepared by incipient wet impregnation method and used for studying the catalytic reaction behavior of CO2 and methanol in the quartz tube reactor under low temperature hydrogen plasma. Results show that the Cu crystal surface dispersed evenly on the surface of Cu/Al2O3 could adsorb and dissociate the CO2, and the electrons were transfered to CO2 molecules and generated the activated state of CO2- species. The reaction products contained dimethyl ether, acetaldehyde, acetone, methanol, ethanol, 1,1-dimethoxy ethanol, dimethyl carbonate (DMC) and acetic acid, and the yield of DMC (pDMC/pMeOH,0)was 9.2%.%采用等体积浸渍法制备了Al2O3负载Cu催化剂,用于低温氢等离子体法研究CO2和甲醇在石英管反应器中的催化反应性能。结果表明,Cu/Al2O3表面均匀分散Cu的晶体表面可以解离吸附CO2,将电子传递到CO2分子中,生成了活化态CO2–物种。 CO2和甲醇在Cu/Al2O3表面上反应的产物有二甲醚、乙醛、丙酮、甲醇、乙醇、1,1-二甲氧基乙醇、碳酸二甲酯(DMC)、乙酸等物质,其生成DMC的转化率达9.2%。

  8. ARGAZ: a new device for experimental study of the coupling between hydrogen production and hydrogen transfer through saturated Callovian-Oxfordian argillite

    International Nuclear Information System (INIS)

    Document available in extended abstract form only. A specific experimental device has been designed to produce hydrogen at the metal-argillite interface by electrochemistry. The target is for one hand to reproduce the production of hydrogen occurring when a metal is corroded by the water contained in the porosity of the mud-stone. On the other hand, the transfer of the hydrogen through the mud-stone can be studied. The specific features of the experiment are the following: - Hydrogen is generated inside a cell by electrochemistry, at the interface between the argillite and a metallic surface; no gas injection is required; - Electrochemistry gives the possibility to control the hydrogen production rate; - Hydrogen generation implies water consumption: the water comes from the porosity of the bulk argillite, near the interface; - That one-dimensional experiment has been built around a cylindrical sample of bulk and undamaged argillite coming from the Callovian-Oxfordian formation. Inside the device a cylindrical sample of argillite is placed above a nickel plate. Around the argillite, a ring of compacted bentonite ensures a mechanical confinement. When saturated, the bentonite will apply a swelling pressure close to the total pressure encountered by the sample in the geological formation. The hydrogen is generated at the interface nickel-argillite. The nickel plate is one of the two electrodes required for electrochemistry. At the top face of bentonite, iron electrode is used to close the electrical circuit. The hydrogen produced at the bottom face of the mud-stone is expected to go across the argillite towards the top face. A porous plate connected with a sampling bottle allows the capture of hydrogen. The argillite sample has a diameter of 50 mm, and a height of 50 mm. It is obtained by over-coring a core sample, and by a careful machining leading to a perfect geometry and surface quality. The production rate of hydrogen can be calculated from the current intensity

  9. Catalytic methanol dissociation

    International Nuclear Information System (INIS)

    Results of the methanol dissociation study on copper/potassium catalyst with alumina support at various temperatures are presented. The following gaseous and liquid products at. The catalytic methanol dissociation is obtained: hydrogen, carbon monoxide, carbon dioxide, methane, and dimethyl ether. Formation rates of these products are discussed. Activation energies of corresponding reactions are calculated

  10. One-pot reduction of 5-hydroxymethylfurfural via hydrogen transfer from supercritical methanol

    DEFF Research Database (Denmark)

    Hansen, Thomas Søndergaard; Barta, Katalin; Anastas, Paul T.;

    2012-01-01

    Catalytic conversion of HMF to valuable chemicals was achieved over a Cu-doped porous metal oxide in supercritical methanol. The hydrotalcite catalyst precursor is prepared following simple synthetic procedures, using inexpensive and earth-abundant starting materials in aqueous solutions. The hyd...

  11. Vacuum-insulated catalytic converter

    Energy Technology Data Exchange (ETDEWEB)

    Benson, David K. (Golden, CO)

    2001-01-01

    A catalytic converter has an inner canister that contains catalyst-coated substrates and an outer canister that encloses an annular, variable vacuum insulation chamber surrounding the inner canister. An annular tank containing phase-change material for heat storage and release is positioned in the variable vacuum insulation chamber a distance spaced part from the inner canister. A reversible hydrogen getter in the variable vacuum insulation chamber, preferably on a surface of the heat storage tank, releases hydrogen into the variable vacuum insulation chamber to conduct heat when the phase-change material is hot and absorbs the hydrogen to limit heat transfer to radiation when the phase-change material is cool. A porous zeolite trap in the inner canister absorbs and retains hydrocarbons from the exhaust gases when the catalyst-coated substrates and zeolite trap are cold and releases the hydrocarbons for reaction on the catalyst-coated substrate when the zeolite trap and catalyst-coated substrate get hot.

  12. Solvent-dependent excited-state hydrogen transfer and intersystem crossing in 2-(2′-hydroxyphenyl)-benzothiazole

    KAUST Repository

    Aly, Shawkat Mohammede

    2015-02-12

    The excited-state intramolecular hydrogen transfer (ESIHT) of 2-(2′-hydroxyphenyl) benzothiazole (HBT) has been investigated in a series of nonpolar, polar aprotic, and polar protic solvents. A variety of state-of-the-art experimental methods were employed, including femto- and nanosecond transient absorption and fluorescence upconversion spectroscopy with broadband capabilities. We show that the dynamics and mechanism of ESIHT of the singlet excited HBT are strongly solvent-dependent. In nonpolar solvents, the data demonstrate that HBT molecules adopt a closed form stabilized by O-H⋯N chelated hydrogen bonds with no twisting angle, and the photoinduced H transfer occurs within 120 fs, leading to the formation of a keto tautomer. In polar solvents, owing to dipole-dipole cross talk and hydrogen bonding interactions, the H transfer process is followed by ultrafast nonradiative deactivation channels, including ultrafast internal conversion (IC) and intersystem crossing (ISC). This is likely to be driven by the twisting motion around the C-C bond between the hydroxyphenyl and thiazole moieties, facilitating the IC back to the enol ground state or to the keto triplet state. In addition, our femtosecond time-resolved fluorescence experiments indicate, for the first time, that the lifetime of the enol form in ACN is approximately 280 fs. This observation indicates that the solvent plays a crucial role in breaking the H bond and deactivating the excited state of the HBT. Interestingly, the broadband transient absorption and fluorescence up-conversion data clearly demonstrate that the intermolecular proton transfer from the excited HBT to the DMSO solvent is about 190 fs, forming the HBT anion excited state.

  13. Study of the catalytic reduction or uranyl nitrate by hydrogen. Sizing of a three-phase reactor

    International Nuclear Information System (INIS)

    As solutions generated by nuclear fuel processing plants contain a mixing of uranium VI (uranyl nitrate) and of plutonium IV, and as uranous nitrate can be used to reduce plutonium to its valence III, this last reduction reaction raises many problems, and the first objective of this research thesis is to better understand and control the various phenomena involved in this reaction. Thus, a first part addresses the reaction chemistry and kinetics. It is based on tests performed in a closed reactor, and aims at clarifying problems of re-oxidation and at devising a kinetic model. A specific attention is paid to matter transfers between the different gaseous, liquid and solid phases. In the second part, the author reports the study of the hydrodynamic behaviour of an airlift-type reactor. Such an apparatus displays indeed interesting benefits to implement the reaction. It notably allows temperature to be well controlled, and the catalyst to be easier handled. Based on these kinetic and hydrodynamic studies, the third part proposes a reactor model, and reports the calculation of its performance by simulation

  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. Selective catalytic reduction of nitrogen oxides from industrial gases by hydrogen or methane; Reduction catalytique selective des oxydes d'azote (NO{sub x}) provenant d'effluents gazeux industriels par l'hydrogene ou le methane

    Energy Technology Data Exchange (ETDEWEB)

    Engelmann Pirez, M

    2004-12-15

    This work deals with the selective catalytic reduction of nitrogen oxides (NO{sub x}), contained in the effluents of industrial plants, by hydrogen or methane. The aim is to replace ammonia, used as reducing agent, in the conventional process. The use of others reducing agents such as hydrogen or methane is interesting for different reasons: practical, economical and ecological. The catalyst has to convert selectively NO into N{sub 2}, in presence of an excess of oxygen, steam and sulfur dioxide. The developed catalyst is constituted by a support such as perovskites, particularly LaCoO{sub 3}, on which are dispersed noble metals (palladium, platinum). The interaction between the noble metal and the support, generated during the activation of the catalyst, allows to minimize the water and sulfur dioxide inhibitor phenomena on the catalytic performances, particularly in the reduction of NO by hydrogen. (O.M.)

  16. Fabrication of a form- and size-variable microcellular-polymer-stabilized metal nanocomposite using supercritical foaming and impregnation for catalytic hydrogenation

    Science.gov (United States)

    Liao, Weisheng; Wu, Ben-Zen; Nian, Hungchi; Chen, Hsiang-Yu; Yu, Jya-Jyun; Chiu, KongHwa

    2012-05-01

    This article presents the fabrication of size-controllable and shape-flexible microcellular high-density polyethylene-stabilized palladium nanoparticles (Pd/m-HDPE) using supercritical foaming, followed by supercritical impregnation. These nanomaterials are investigated for use as heterogeneous hydrogenation catalysts of biphenyls in supercritical carbon dioxide with no significant surface and inner mass transfer resistance. The morphology of the Pd/m-HDPE is examined using scanning electron microscopy images of the pores inside Pd/m-HDPE catalysts and transmission electron microscopy images of the Pd particles confined in an HDPE structure. This nanocomposite simplifies industrial design and operation. These Pd/m-HDPE catalysts can be recycled easily and reused without complex recovery and cleaning procedures.

  17. Ground state isomerism in betacarboline hydrogen bond complexes: The charge transfer nature of its large Stokes shifted emission

    Energy Technology Data Exchange (ETDEWEB)

    Sanchez-Coronilla, Antonio; Balon, Manuel; Munoz, Maria A.; Hidalgo, Jose [Departamento de Quimica Fisica, Facultad de Farmacia, Universidad de Sevilla, 41012 Sevilla (Spain); Carmona, Carmen [Departamento de Quimica Fisica, Facultad de Farmacia, Universidad de Sevilla, 41012 Sevilla (Spain)], E-mail: carmona@us.es

    2008-07-03

    The hydrogen bonding and excited state proton transfer reactions between betacarboline, 9H-pyrido[3,4-b]indole, BC, and 1,1,1,3,3,3-hexafluoropropan-2-ol, HFIP, have been studied in the aprotic solvents cyclohexane and toluene by absorption, steady state and time resolved fluorescence measurements. On the basis of these results and those of previous works (Refs. [A. Sanchez-Coronilla, C. Carmona, M.A. Munoz, M. Balon, Chem. Phys., 327 (2006) 70] and [A. Sanchez-Coronilla, M. Balon, M.A. Munoz, C. Carmona, Chem. Phys. 344 (2008) 72]) two main fundamental conclusions can be drawn on the photophysical behaviour of BC. Thus, it is shown, for the first time, that the non-cyclic double hydrogen bond complexes formed through both nitrogen atoms of BC, DHB, can suffer, in their ground state, an isomerisation process. These adducts acquire a quinoid structure in cyclohexane, but maintain a dipolar zwitterionic structure in toluene. Moreover, it is concluded that the observed large Stokes shifted emission, around 520 nm, is not due, as it has been so far generally accepted, to the emission of a BC zwitterionic phototautomer, but to the intramolecular charge transfer, ICT, excited state emissions of the DHB hydrogen bond adducts.

  18. Hydrogen-transfer and charge transfer in photochemical and high energy radiation induced reactions: effects of thiols. Final report, February 1, 1960-january 31, 1979

    International Nuclear Information System (INIS)

    Absorption of ultraviolet or visible light, or high energy radiation, may lead to highly reactive free radicals. Thiols affect the reactions of these radicals in the following ways: (1) transfer of hydrogen from sulfur of the thiol to a substrate radical, converting the radical to a stable molecule, and the thiol to a reactive thiyl radical; and (2) transfer of hydrogen from a substrate radical or molecule to thiyl, regenerating thiol. The thiol is thus used repeatedly and a single molecule may affect the consequences of many quanta. Three effects may ensue, depending upon the system irradiated: (1) the substrate radicals may be converted by thiol-thiyl to the original molecules, and protection against radiation damage is afforded. (2) The radicals may be converted to molecules not identical with the starting materials, and in both cases damage caused by radical combination processes is prevented. (3) Product yields may be increased where the initial radicals might otherwise regenerate starting materials. It was shown that rates of reaction of excited species can be correlated with triplet energies and reduction potentials, and with ionization potentials, that amines are very reactive toward excited carbonyl compounds of all types, and that yields of products from these reactions can be increased by thiols, leading to increased efficiency in utilization of light

  19. Development of Novel Electrode Materials for the Electrocatalysis of Oxygen-Transfer and Hydrogen-Transfer Reactions

    Energy Technology Data Exchange (ETDEWEB)

    Brett Kimball Simpson

    2002-08-27

    Throughout this thesis, the fundamental aspects involved in the electrocatalysis of anodic O-transfer reactions and cathodic H-transfer reactions have been studied. The investigation into anodic O-transfer reactions at undoped and Fe(III)[doped MnO{sub 2} films] revealed that MnO{sub 2} film electrodes prepared by a cycling voltammetry deposition show improved response for DMSO oxidation at the film electrodes vs. the Au substrate. Doping of the MnO{sub 2} films with Fe(III) further enhanced electrode activity. Reasons for this increase are believed to involve the adsorption of DMSO by the Fe(III) sites. The investigation into anodic O-transfer reactions at undoped and Fe(III)-doped RuO{sub 2} films showed that the Fe(III)-doped RuO{sub 2}-film electrodes are applicable for anodic detection of sulfur compounds. The Fe(III) sites in the Fe-RuO{sub 2} films are speculated to act as adsorption sites for the sulfur species while the Ru(IV) sites function for anodic discharge of H{sub 2}O to generate the adsorbed OH species. The investigation into cathodic H-transfer reactions, specifically nitrate reduction, at various pure metals and their alloys demonstrated that the incorporation of metals into alloy materials can create a material that exhibits bifunctional properties for the various steps involved in the overall nitrate reduction reaction. The Sb{sub 10}Sn{sub 20}Ti{sub 70}, Cu{sub 63}Ni{sub 37} and Cu{sub 25}Ni{sub 75} alloy electrodes exhibited improved activity for nitrate reduction as compared to their pure component metals. The Cu{sub 63}Ni{sub 37} alloy displayed the highest activity for nitrate reduction. The final investigation was a detailed study of the electrocatalytic activity of cathodic H-transfer reactions (nitrate reduction) at various compositions of Cu-Ni alloy electrodes. Voltammetric response for NO{sub 3}{sup -} at the Cu-Ni alloy electrode is superior to the response at the pure Cu and Ni electrodes. This is explained on the basis of the

  20. Intermolecular electron transfer from intramolecular excitation and coherent acoustic phonon generation in a hydrogen-bonded charge-transfer solid.

    Science.gov (United States)

    Rury, Aaron S; Sorenson, Shayne; Dawlaty, Jahan M

    2016-03-14

    Organic materials that produce coherent lattice phonon excitations in response to external stimuli may provide next generation solutions in a wide range of applications. However, for these materials to lead to functional devices in technology, a full understanding of the possible driving forces of coherent lattice phonon generation must be attained. To facilitate the achievement of this goal, we have undertaken an optical spectroscopic study of an organic charge-transfer material formed from the ubiquitous reduction-oxidation pair hydroquinone and p-benzoquinone. Upon pumping this material, known as quinhydrone, on its intermolecular charge transfer resonance as well as an intramolecular resonance of p-benzoquinone, we find sub-cm(-1) oscillations whose dispersion with probe energy resembles that of a coherent acoustic phonon that we argue is coherently excited following changes in the electron density of quinhydrone. Using the dynamical information from these ultrafast pump-probe measurements, we find that the fastest process we can resolve does not change whether we pump quinhydrone at either energy. Electron-phonon coupling from both ultrafast coherent vibrational and steady-state resonance Raman spectroscopies allows us to determine that intramolecular electronic excitation of p-benzoquinone also drives the electron transfer process in quinhydrone. These results demonstrate the wide range of electronic excitations of the parent of molecules found in many functional organic materials that can drive coherent lattice phonon excitations useful for applications in electronics, photonics, and information technology. PMID:26979698

  1. Peculiarities of tritium mass transfer in high-temperature NPP with sodium coolant for hydrogen production

    International Nuclear Information System (INIS)

    The calculation technique of characteristics of sodium cleanup system (CS) from hydrogen (tritium) using its vacuum-pumping through special membranes with increased hydrogen permeability is given. It is pointed out that purification of sodium from tritium to concentrations providing maximum permissible concentration in produced hydrogen lays additional claims to CS from hydrogen. Using secondary circuit sodium CS which provides tritium concentration in the product produced in the tertiary circuit not exceeding maximum permissible concentration, tritium entry into the environment runs about ⁓4x104 Bq/s. Requirements of normal ecological situation are achieved by the methods widely used now in nuclear industry. Under these conditions 98% of tritium will be accumulated in secondary circuit sodium CS, 0.6% - in environment, 1.3% - in finish product

  2. Hydrogen storage via polyhydride complexes

    Energy Technology Data Exchange (ETDEWEB)

    Jensen, C.M. [Univ. of Hawaii, Honolulu, HI (United States)

    1996-10-01

    Polyhydride metal complexes are being developed for application to hydrogen storage. Complexes have been found which catalyze the reversible hydrogenation of unsaturated hydrocarbons. This catalytic reaction could be the basis for a low temperature, hydrogen storage system with a available hydrogen density greater than 7 weight percent. The P-C-P pincer complexes, RhH{sub 2}(C{sub 6}H{sub 3}-2,6-(CH{sub 2}PBu{sup t}{sub 2}){sub 2}) and IrH{sub 2}(C{sub 6}H{sub 3}-2,6-(CH{sub 2}PBu{sup t}{sub 2}){sub 2}) have unprecedented, long term stability at elevated temperatures. The novel iridium complex catalyzes the transfer dehydrogenation of cycloctane to cyclooctene at the rate of 716 turnovers/h which is 2 orders of magnitude greater than that found for previously reported catalytic systems which do not require the sacrificial hydrogenation of a large excess of hydrogen acceptor.

  3. Elastic, charge transfer, and related transport cross sections for proton impact of atomic hydrogen for astrophysical and laboratory plasma modeling

    Science.gov (United States)

    Schultz, D. R.; Ovchinnikov, S. Yu; Stancil, P. C.; Zaman, T.

    2016-04-01

    Updating and extending previous work (Krstić and Schultz 1999 J. Phys. B: At. Mol. Opt. Phys. 32 3458 and other references) comprehensive calculations were performed for elastic scattering and charge transfer in proton—atomic hydrogen collisions. The results, obtained for 1301 collision energies in the center-of-mass energy range of 10‑4–104 eV, are provided for integral and differential cross sections relevant to transport modeling in astrophysical and other plasma environments, and are made available through a website. Use of the data is demonstrated through a Monte Carlo transport simulation of solar wind proton propagation through atomic hydrogen gas representing a simple model of the solar wind interaction with heliospheric neutrals.

  4. 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.

  5. Variable photosynthetic units, energy transfer and light-induced evolution of hydrogen in algae and bacteria.

    Science.gov (United States)

    Gaffron, H.

    1971-01-01

    The present state of knowledge regarding the truly photochemical reactions in photosynthesis is considered. Nine-tenths of the available knowledge is of a biochemical nature. Questions regarding the activities of the chlorophyll system are examined. The simplest photochemical response observed in living hydrogen-adapted algal cells is the release of molecular hydrogen, which continues even after all other known natural reactions have been eliminated either by heating or the action of poisons.

  6. Progresses in Catalytic Steam Reforming of Bio-oil for Hydrogen Production%生物油水蒸气催化重整制氢研究进展

    Institute of Scientific and Technical Information of China (English)

    张文涛; 陈明强; 刘少敏; 杨忠连

    2014-01-01

    氢气作为一种环境友好的清洁能源,人们对它的关注度越来越高。生物油水蒸气催化重整制氢是未来制氢的一种可行性方案。本文综述了近年来生物油水蒸气重整制氢的研究进展。主要从重整制氢反应机理、热力学分析、催化重整催化剂、代表性的重整反应器方面进行讨论,指出催化重整中的主要问题是碳沉积导致催化剂失活。研制高活性、高稳定性、高选择性的催化剂是生物油催化重整制氢的关键。%Hydrogen is regarded as an environmentally friendly clean energy and has been paid more and more attention. Catalytic steam reforming of bio-oil is a feasible solution for future hydrogen production. The recent progress of catalytic steam reforming of bio-oil for hydrogen production was reviewed in this paper. Some respects such as reaction mechanism, thermodynamic analysis, catalysts, and typical reactors of catalytic steam reforming of bio-oil were discussed. The deactivation of catalyst caused by carbon deposition is pointed out as the main problem during the reforming process. Therefore, the key factor of catalytic reforming of bio-oil is to develop high activity, high stability, and high selectivity catalysts.

  7. Cross sections for ion-molecular reactions in hydrogen systems and for charge transfer reactions of slow multiply charged ions

    International Nuclear Information System (INIS)

    Cross sections of ion-molecular reactions in hydrogen systems of H+-H2, H2+-H2 and H3+-H2 and charge transfer cross sections of multiply charged ions in atomic and molecular targets are presented in graphs and tables of the part A, B and C. All data presented for 99 collision systems have been measured systematically using an octo-pole ion beam guide (OPIG) technique till now since 1985. The part A is for ion-molecular reactions in hydrogen systems. In the lower energy region below few eV in center-of-mass systems, it is seen obviously at a glance that the ion-molecular reaction in hydrogen systems is dominated by H3+ formation process. In the energy region from few eV to few hundred eV in center-of-mass systems, many reaction channels of decay processes from intermediate molecular states seem to be opened resonantly. Some of cross section data in the part B for charge transfer reactions of low-charged ions produced by a conventional electron impact type (Nier type) ion source should be noted to strongly depend on the electron impact energy due to contamination of low lying metastable states in projectile ions. The part C is for charge transfer reactions of multiply charged ions extracted from a small type of electron beam ion source (Mini-EBIS). In measurements using the mini-EBIS, no evidence of metastable ions existing in the primary ion beam has been found except for doubly charged ion beam. The higher energy end of the present cross sections are connected with previous data in fairly good

  8. Efficient Access to Chiral Benzhydrols via Asymmetric Transfer Hydrogenation of Unsymmetrical Benzophenones with Bifunctional Oxo-Tethered Ruthenium Catalysts.

    Science.gov (United States)

    Touge, Taichiro; Nara, Hideki; Fujiwhara, Mitsuhiko; Kayaki, Yoshihito; Ikariya, Takao

    2016-08-17

    A concise asymmetric transfer hydrogenation of diaryl ketones, promoted by bifunctional Ru complexes with an etherial linkage between 1,2-diphenylethylenediamine (DPEN) and η(6)-arene ligands, was successfully developed. Because of the effective discrimination of substituents at the ortho position on the aryl group, unsymmetrical benzophenones were smoothly reduced in a 5:2 mixture of formic acid and triethylamine with an unprecedented level of excellent enantioselectivity. For the non-ortho-substituted benzophenones, the oxo-tethered catalyst electronically discerned biased substrates, resulting in attractive performance yielding chiral diarylmethanols with >99% ee. PMID:27463264

  9. Nanostructured RuO2 on MWCNTs: Efficient catalyst for transfer hydrogenation of carbonyl compounds and aerial oxidation of alcohols

    OpenAIRE

    Gopiraman, M; Babu, S. Ganesh; Karvembu, R.; Kim, I. S.

    2014-01-01

    Multiwall carbon nanotubes (MWCNTs)/ruthenium dioxide nanoparticles (RuO2NPs) composite was prepared by a straightforward ‘dry synthesis’ method. After being well characterized, the prepared composite was used as a nanocatalyst (RuO2/MWCNT) for the transfer hydrogenation of carbonyl compounds. The excellent adhesion of RuO2NPs on the anchoring sites of MWCNTs was confirmed by TEM and Raman analyses. The weight percentage (7.97 wt%) and the chemical state (+4) of Ru in RuO2/MWCNT was confirmed...

  10. Antioxidant Activity/Capacity Measurement. 2. Hydrogen Atom Transfer (HAT)-Based, Mixed-Mode (Electron Transfer (ET)/HAT), and Lipid Peroxidation Assays.

    Science.gov (United States)

    Apak, Reşat; Özyürek, Mustafa; Güçlü, Kubilay; Çapanoğlu, Esra

    2016-02-10

    Measuring the antioxidant activity/capacity levels of food extracts and biological fluids is useful for determining the nutritional value of foodstuffs and for the diagnosis, treatment, and follow-up of numerous oxidative stress-related diseases. Biologically, antioxidants play their health-beneficial roles via transferring a hydrogen (H) atom or an electron (e(-)) to reactive species, thereby deactivating them. Antioxidant activity assays imitate this action; that is, antioxidants are measured by their H atom transfer (HAT) or e(-) transfer (ET) to probe molecules. Antioxidant activity/capacity can be monitored by a wide variety of assays with different mechanisms, including HAT, ET, and mixed-mode (ET/HAT) assays, generally without distinct boundaries between them. Understanding the principal mechanisms, advantages, and disadvantages of the measurement assays is important for proper selection of method for valid evaluation of antioxidant properties in desired applications. This work provides a general and up-to-date overview of HAT-based, mixed-mode (ET/HAT), and lipid peroxidation assays available for measuring antioxidant activity/capacity and the chemistry behind them, including a critical evaluation of their advantages and drawbacks. PMID:26805392

  11. Forced convection heat transfer from a wire inserted into a vertically-mounted pipe to liquid hydrogen flowing upward

    International Nuclear Information System (INIS)

    Forced convection heat transfer from a PtCo wire with a length of 120 mm and a diameter of 1.2 mm that was inserted into a vertically-mounted pipe with a diameter of 8.0 mm to liquid hydrogen flowing upward was measured with a quasi-steady increase of a heat generation rate for wide ranges of flow rate under saturated conditions. The pressures were varied from 0.4 MPa to 1.1 MPa. The non-boiling heat transfer characteristic agrees with that predicted by Dittus-Boelter correlation. The critical heat fluxes are higher for higher flow rates and lower pressures. Effect of Weber number on the CHF was clarified and a CHF correlation that can describe the experimental data is derived based on our correlation for a pipe

  12. Non-catalytic plasma-arc reforming of natural gas with carbon dioxide as the oxidizing agent for the production of synthesis gas or hydrogen - HTR2008-58023

    International Nuclear Information System (INIS)

    The world's energy consumption is increasing constantly due to the growing population of the world. The increasing energy consumption has a negative effect on the fossil fuel reserves of the world. Hydrogen has the potential to provide energy for all our needs by making use of fossil fuel such as natural gas and nuclear-based electricity. Hydrogen can be produced by reforming methane with carbon dioxide as the oxidizing agent. Hydrogen can be produced in a Plasma-arc reforming unit making use of the heat energy generated by a 500 MWt Pebble Bed Modular Reactor (PBMR). The reaction in the unit takes place stoichiometrically in the absence of a catalyst. Steam can be added to the feed stream together with the Carbon Dioxide, which make it possible to control the H2/CO ratio in the synthesis gas between 1/1 and 3/1. This ratio of H2/CO in the synthesis gas is suitable to be used as feed gas to almost any chemical and petrochemical process. To increase the hydrogen production further, the Water-Gas Shift Reaction can be applied. A techno-economic analysis was performed on the non-catalytic plasma-arc reforming process. The capital cost of the plant is estimated at $463 million for the production of 1 132 million Nm3/year of hydrogen. The production cost of hydrogen is in the order of $12.81 per GJ depending on the natural gas cost and the price of electricity. (authors)

  13. Effects of low-temperature catalytic pretreatments on coal structure and reactivity in liquefaction. Final technical report, Volume 2 - hydrogenative and hydrothermal pretreatments and spectroscopic characterization using pyrolysis-GC-MS, CPMAS {sup 13}C NMR and FT-IR

    Energy Technology Data Exchange (ETDEWEB)

    Chunshan Song; Hatcher, P.G.; Saini, A.K.; Wenzel, K.A.

    1998-01-01

    It has been indicated by DOE COLIRN panel that low-temperature catalytic pretreatment is a promising approach to the development of an improved liquefaction process. This work is a fundamental study on effects of pretreatments on coal structure and reactivity in liquefaction. The main objectives of this project are to study the coal structural changes induced by low-temperature catalytic and thermal pretreatments by using spectroscopic techniques; and to clarify the pretreatment-induced changes in reactivity or convertibility of coals. As the second volume of the final report, here we summarize our work on spectroscopic characterization of four raw coals including two subbituminous coals and two bituminous coals, tetrahydrofuran (THF)-extracted but unreacted coals, the coals (THF-insoluble parts) that have been thermally pretreated. in the absence of any solvents and in the presence of either a hydrogen-donor solvent or a non-donor solvent, and the coals (THF-insoluble parts) that have been catalytically pretreated in the presence of a dispersed Mo sulfide catalyst in the absence of any solvents and in the presence of either a hydrogen-donor solvent or a non-donor solvent.

  14. Study on transfer-free graphene synthesis process utilizing spontaneous agglomeration of catalytic Ni and Co metals

    International Nuclear Information System (INIS)

    Transfer-free graphene synthesis process utilizing metal agglomeration phenomena was investigated by using carbon films deposited on Ni or Co catalyst metals on SiO2/Si substrates. As a result of metal agglomeration at high temperatures, multilayer graphene films appeared to be formed directly on SiO2 films. The microscopic Raman mapping study revealed that graphene films were preferentially synthesized around areas where metal films disappeared at an early stage of agglomeration, and that they finally covered almost the whole surface. It was also found that the synthesized graphene films tended to have better structural qualities and lower layer numbers with the increase in the starting metal thicknesses regardless of the kinds of catalyst metals. Raman study also showed that they had good two-dimensional uniformity in the structural quality. (paper)

  15. Fluidic hydrogen detector production prototype development

    Science.gov (United States)

    Roe, G. W.; Wright, R. E.

    1976-01-01

    A hydrogen gas sensor that can replace catalytic combustion sensors used to detect leaks in the liquid hydrogen transfer systems at Kennedy Space Center was developed. A fluidic sensor concept, based on the principle that the frequency of a fluidic oscillator is proportional to the square root of the molecular weight of its operating fluid, was utilized. To minimize sensitivity to pressure and temperature fluctuations, and to make the sensor specific for hydrogen, two oscillators are used. One oscillator operates on sample gas containing hydrogen, while the other operates on sample gas with the hydrogen converted to steam. The conversion is accomplished with a small catalytic converter. The frequency difference is taken, and the hydrogen concentration computed with a simple digital processing circuit. The output from the sensor is an analog signal proportional to hydrogen content. The sensor is shown to be accurate and insensitive to severe environmental disturbances. It is also specific for hydrogen, even with large helium concentrations in the sample gas.

  16. Anti-oxidant activity of 6-gingerol as a hydroxyl radical scavenger by hydrogen atom transfer, radical addition and electron transfer mechanisms

    Indian Academy of Sciences (India)

    MANISH K TIWARI; P C MISHRA

    2016-08-01

    Mechanisms of anti-oxidant action of 6-gingerol as a hydroxyl radical scavenger have been investigated using the transition state theory within the framework of density functional theory. Hydrogen abstraction by a hydroxyl radical from the different sites of 6-gingerol and addition of the former to the different sites ofthe latter were studied. Electron transfer from 6-gingerol to a hydroxyl radical was also studied. Solvent effect in aqueous media was treated using the integral equation formalism of the polarizable continuum model (IEFPCM). Reaction rate constants in aqueous media were generally found to be larger than those in gas phase. The tunneling contributions to rate constants were found to be appreciable. Our results show that 6-gingerol is an excellent anti-oxidant and would scavenge hydroxyl radicals efficiently.

  17. In-situ diagnostic tools for hydrogen transfer leak characterization in PEM fuel cell stacks part II: Operational applications

    Science.gov (United States)

    Niroumand, Amir M.; Homayouni, Hooman; DeVaal, Jake; Golnaraghi, Farid; Kjeang, Erik

    2016-08-01

    This paper describes a diagnostic tool for in-situ characterization of the rate and distribution of hydrogen transfer leaks in Polymer Electrolyte Membrane (PEM) fuel cell stacks. The method is based on reducing the air flow rate from a high to low value at a fixed current, while maintaining an anode overpressure. At high air flow rates, the reduction in air flow results in lower oxygen concentration in the cathode and therefore reduction in cell voltages. Once the air flow rate in each cell reaches a low value at which the cell oxygen-starves, the voltage of the corresponding cell drops to zero. However, oxygen starvation results from two processes: 1) the electrochemical oxygen reduction reaction which produces current; and 2) the chemical reaction between oxygen and the crossed over hydrogen. In this work, a diagnostic technique has been developed that accounts for the effect of the electrochemical reaction on cell voltage to identify the hydrogen leak rate and number of leaky cells in a fuel cell stack. This technique is suitable for leak characterization during fuel cell operation, as it only requires stack air flow and voltage measurements, which are readily available in an operational fuel cell system.

  18. Protein hydrogen exchange measured at single-residue resolution by electron transfer dissociation mass spectrometry

    DEFF Research Database (Denmark)

    Rand, Kasper D; Zehl, Martin; Jensen, Ole Nørregaard;

    2009-01-01

    Because of unparalleled sensitivity and tolerance to protein size, mass spectrometry (MS) has become a popular method for measuring the solution hydrogen (1H/2H) exchange (HX) of biologically relevant protein states. While incorporated deuterium can be localized to different regions by pepsin...

  19. Catalytic Hydrogenation of CO2 to Methanol: Study of Synergistic Effect on Adsorption Properties of CO2 and H2 in CuO/ZnO/ZrO2 System

    Directory of Open Access Journals (Sweden)

    Chunjie Huang

    2015-11-01

    Full Text Available A series of CuO/ZnO/ZrO2 (CZZ catalysts with different CuO/ZnO weight ratios have been synthesized by citrate method and tested in the catalytic hydrogenation of CO2 to methanol. Experimental results showed that the catalyst with the lowest CuO/ZnO weight ratio of 2/7 exhibited the best catalytic performance with a CO2 conversion of 32.9%, 45.8% methanol selectivity, and a process delivery of 193.9 gMeOH·kgcat−1·h−1. A synergetic effect is found by systematic temperature-programmed-desorption (TPD studies. Comparing with single and di-component systems, the interaction via different components in a CZZ system provides additional active sites to adsorb more H2 and CO2 in the low temperature range, resulting in higher weight time yield (WTY of methanol.

  20. 负载型Pd/SBA-15催化剂催化性能研究%Research on catalytic hydrogenation performance of Pd/SBA-15 supported catalyst

    Institute of Scientific and Technical Information of China (English)

    刘大伟

    2012-01-01

    The hydrogenation of 2-nitrochlorobenzene is carried out by Pd/SBA-15 supported catalyst. The effect of temperature and amount of catalysts on catalytic activity and life-span are investigated. The results show that Pd/SBA-15 supported catalyst has excellent catalytic performance and is expected to be applied in industry.%将负载型催化剂Pd/SBA-15用于催化邻氯硝基苯加氢.考察了反应温度、催化剂用量对Pd/SBA-15催化性能的影响,并考察了催化剂的使用寿命.实验结果表明,Pd/SBA-15催化剂表现出很好的催化性能,有望应用于工业生产.