WorldWideScience

Sample records for catalytic reactions experiments

  1. Engineering reactors for catalytic reactions

    Indian Academy of Sciences (India)

    Vivek V Ranade

    2014-03-01

    Catalytic reactions are ubiquitous in chemical and allied industries. A homogeneous or heterogeneous catalyst which provides an alternative route of reaction with lower activation energy and better control on selectivity can make substantial impact on process viability and economics. Extensive studies have been conducted to establish sound basis for design and engineering of reactors for practising such catalytic reactions and for realizing improvements in reactor performance. In this article, application of recent (and not so recent) developments in engineering reactors for catalytic reactions is discussed. Some examples where performance enhancement was realized by catalyst design, appropriate choice of reactor, better injection and dispersion strategies and recent advances in process intensification/ multifunctional reactors are discussed to illustrate the approach.

  2. Fluctuations in catalytic surface reactions

    CERN Document Server

    Imbihl, R

    2003-01-01

    The internal reaction-induced fluctuations which occur in catalytic CO oxidation on a Pt field emitter tip have been studied using field electron microscopy (FEM) as a spatially resolving method. The structurally heterogeneous Pt tip consists of facets of different orientations with nanoscale dimensions. The FEM resolution of roughly 2 nm corresponds to a few hundred reacting adsorbed particles whose variations in the density are imaged as brightness fluctuations. In the bistable range of the reaction one finds fluctuation-induced transitions between the two stable branches of the reaction kinetics. The fluctuations exhibit a behaviour similar to that of an equilibrium phase transition, i.e. the amplitude diverges upon approaching the bifurcation point terminating the bistable range of the reaction. Simulations with a hybrid Monte Carlo/mean-field model reproduce the experimental observations. Fluctuations on different facets are typically uncorrelated but within a single facet a high degree of spatial cohere...

  3. Catalytic, enantioselective, vinylogous aldol reactions.

    Science.gov (United States)

    Denmark, Scott E; Heemstra, John R; Beutner, Gregory L

    2005-07-25

    In 1935, R. C. Fuson formulated the principle of vinylogy to explain how the influence of a functional group may be felt at a distant point in the molecule when this position is connected by conjugated double-bond linkages to the group. In polar reactions, this concept allows the extension of the electrophilic or nucleophilic character of a functional group through the pi system of a carbon-carbon double bond. This vinylogous extension has been applied to the aldol reaction by employing "extended" dienol ethers derived from gamma-enolizable alpha,beta-unsaturated carbonyl compounds. Since 1994, several methods for the catalytic, enantioselective, vinylogous aldol reaction have appeared, with which varying degrees of regio- (site), enantio-, and diastereoselectivity can be attained. In this Review, the current scope and limitations of this transformation, as well as its application in natural product synthesis, are discussed. PMID:15940727

  4. Kinetics of heterogeneous catalytic reactions

    CERN Document Server

    Boudart, Michel

    2014-01-01

    This book is a critical account of the principles of the kinetics of heterogeneous catalytic reactions in the light of recent developments in surface science and catalysis science. Originally published in 1984. The Princeton Legacy Library uses the latest print-on-demand technology to again make available previously out-of-print books from the distinguished backlist of Princeton University Press. These paperback editions preserve the original texts of these important books while presenting them in durable paperback editions. The goal of the Princeton Legacy Library is to vastly increase acc

  5. Electrochemical promotion of catalytic reactions

    Science.gov (United States)

    Imbihl, R.

    2010-05-01

    The electrochemical promotion of heterogeneously catalyzed reactions (EPOC) became feasible through the use of porous metal electrodes interfaced to a solid electrolyte. With the O 2- conducting yttrium stabilized zirconia (YSZ), the Na + conducting β″-Al 2O 3 (β-alumina), and several other types of solid electrolytes the EPOC effect has been demonstrated for about 100 reaction systems in studies conducted mainly in the mbar range. Surface science investigations showed that the physical basis for the EPOC effect lies in the electrochemically induced spillover of oxygen and alkali metal, respectively, onto the surface of the metal electrodes. For the catalytic promotion effect general concepts and mechanistic schemes were proposed but these concepts and schemes are largely speculative. Applying surface analytical tools to EPOC systems the proposed mechanistic schemes can be verified or invalidated. This report summarizes the progress which has been achieved in the mechanistic understanding of the EPOC effect.

  6. Exact Results for Kinetics of Catalytic Reactions

    OpenAIRE

    Frachebourg, L.; Krapivsky, P. L.

    1995-01-01

    The kinetics of an irreversible catalytic reaction on substrate of arbitrary dimension is examined. In the limit of infinitesimal reaction rate (reaction-controlled limit), we solve the dimer-dimer surface reaction model (or voter model) exactly in arbitrary dimension $D$. The density of reactive interfaces is found to exhibit a power law decay for $D

  7. Catalytic reaction in confined flow channel

    Energy Technology Data Exchange (ETDEWEB)

    Van Hassel, Bart A.

    2016-03-29

    A chemical reactor comprises a flow channel, a source, and a destination. The flow channel is configured to house at least one catalytic reaction converting at least a portion of a first nanofluid entering the channel into a second nanofluid exiting the channel. The flow channel includes at least one turbulating flow channel element disposed axially along at least a portion of the flow channel. A plurality of catalytic nanoparticles is dispersed in the first nanofluid and configured to catalytically react the at least one first chemical reactant into the at least one second chemical reaction product in the flow channel.

  8. Catalytic reaction dynamics in inhomogeneous networks.

    Science.gov (United States)

    Watanabe, Akitomo; Yakubo, Kousuke

    2014-05-01

    Biochemical reactions in a cell can be modeled by a catalytic reaction network (CRN). It has been reported that catalytic chain reactions occur intermittently in the CRN with a homogeneous random-graph topology and its avalanche-size distribution obeys a power law with the exponent 4/3 [A. Awazu and K. Kaneko, Phys. Rev. E 80, 010902(R) (2009)]. This fact indicates that the catalytic reaction dynamics in homogeneous CRNs exhibits self-organized criticality (SOC). Structures of actual CRNs are, however, known to be highly inhomogeneous. We study the influence of various types of inhomogeneities found in real-world metabolic networks on the universality class of SOC. Our numerical results clarify that SOC keeps its universality class even for networks possessing structural inhomogeneities such as the scale-free property, community structures, and degree correlations. In contrast, if the CRN has inhomogeneous catalytic functionality, the universality class of SOC depends on how widely distributed the number of reaction paths catalyzed by a single chemical species is. PMID:25353843

  9. Electrochemical Promotion of Catalytic Reactions Using

    DEFF Research Database (Denmark)

    Petrushina, Irina; Bjerrum, Niels; Cleemann, Lars Nilausen;

    2007-01-01

    This paper presents the results of a study on electrochemical promotion (EP) of catalytic reactions using Pt/C/polybenzimidazole(H3PO4)/Pt/C fuel cell performed by the Energy and Materials Science Group (Technical University of Denmark) during the last 6 years[1-4]. The development of our...

  10. From Catalytic Reaction Networks to Protocells

    Science.gov (United States)

    Kaneko, Kunihiko

    2013-12-01

    In spite of recent advances, there still remains a large gape between a set of chemical reactions and a biological cell. Here we discuss several theoretical efforts to fill in the gap. The topics cover (i) slow relaxation to equilibrium due to glassy behavior in catalytic reaction networks (ii) consistency between molecule replication and cell growth, as well as energy metabolism (iii) control of a system by minority molecules in mutually catalytic system, which work as a carrier of genetic information, and leading to evolvability (iv) generation of a compartmentalized structure as a cluster of molecules centered around the minority molecule, and division of the cluster accompanied by the replication of minority molecule (v) sequential, logical process over several states from concurrent reaction dynamics, by taking advantage of discreteness in molecule number.

  11. Catalytic Conia-ene and related reactions.

    Science.gov (United States)

    Hack, Daniel; Blümel, Marcus; Chauhan, Pankaj; Philipps, Arne R; Enders, Dieter

    2015-10-01

    Since its initial inception, the Conia-ene reaction, known as the intramolecular addition of enols to alkynes or alkenes, has experienced a tremendous development and appealing catalytic protocols have emerged. This review fathoms the underlying mechanistic principles rationalizing how substrate design, substrate activation, and the nature of the catalyst work hand in hand for the efficient synthesis of carbocycles and heterocycles at mild reaction conditions. Nowadays, Conia-ene reactions can be found as part of tandem reactions, and the road for asymmetric versions has already been paved. Based on their broad applicability, Conia-ene reactions have turned into a highly appreciated synthetic tool with impressive examples in natural product synthesis reported in recent years. PMID:26031492

  12. Ubiquitous "glassy" relaxation in catalytic reaction networks

    OpenAIRE

    Awazu, Akinori; Kaneko, Kunihiko

    2009-01-01

    Study of reversible catalytic reaction networks is important not only as an issue for chemical thermodynamics but also for protocells. From extensive numerical simulations and theoretical analysis, slow relaxation dynamics to sustain nonequlibrium states are commonly observed. These dynamics show two types of salient behaviors that are reminiscent of glassy behavior: slow relaxation along with the logarithmic time dependence of the correlation function and the emergence of plateaus in the rel...

  13. Ubiquitous ``glassy'' relaxation in catalytic reaction networks

    Science.gov (United States)

    Awazu, Akinori; Kaneko, Kunihiko

    2009-10-01

    Study of reversible catalytic reaction networks is important not only as an issue for chemical thermodynamics but also for protocells. From extensive numerical simulations and theoretical analysis, slow relaxation dynamics to sustain nonequlibrium states are commonly observed. These dynamics show two types of salient behaviors that are reminiscent of glassy behavior: slow relaxation along with the logarithmic time dependence of the correlation function and the emergence of plateaus in the relaxation-time course. The former behavior is explained by the eigenvalue distribution of a Jacobian matrix around the equilibrium state that depends on the distribution of kinetic coefficients of reactions. The latter behavior is associated with kinetic constraints rather than metastable states and is due to the absence of catalysts for chemicals in excess and the negative correlation between two chemical species. Examples are given and generality is discussed with relevance to bottleneck-type dynamics in biochemical reactions as well.

  14. Asymmetric Catalytic Reactions Catalyzed by Chiral Titanium Complexes

    Institute of Scientific and Technical Information of China (English)

    FENG; XiaoMing

    2001-01-01

    Chiral titanium complexes is very importance catalyst to asymmetric catalytic reactions. A series of catalytic systems based on titanium-chiral ligands complexes has been reported. This presentation will discuss some of our recent progress on asymmetric catalytic reactions catalyzed by chiral titanium complexes.  ……

  15. Asymmetric Catalytic Reactions Catalyzed by Chiral Titanium Complexes

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    @@ Chiral titanium complexes is very importance catalyst to asymmetric catalytic reactions. A series of catalytic systems based on titanium-chiral ligands complexes has been reported. This presentation will discuss some of our recent progress on asymmetric catalytic reactions catalyzed by chiral titanium complexes.

  16. Including lateral interactions into microkinetic models of catalytic reactions

    DEFF Research Database (Denmark)

    Hellman, Anders; Honkala, Johanna Karoliina

    2007-01-01

    In many catalytic reactions lateral interactions between adsorbates are believed to have a strong influence on the reaction rates. We apply a microkinetic model to explore the effect of lateral interactions and how to efficiently take them into account in a simple catalytic reaction. Three differ...... different approximations are investigated: site, mean-field, and quasichemical approximations. The obtained results are compared to accurate Monte Carlo numbers. In the end, we apply the approximations to a real catalytic reaction, namely, ammonia synthesis....

  17. Discreteness-Induced Criticality in Random Catalytic Reaction Networks

    OpenAIRE

    Awazu, Akinori; Kaneko, Kunihiko

    2009-01-01

    Universal intermittent dynamics in a random catalytic reaction network, induced by smallness in the molecule number is reported. Stochastic simulations for a random catalytic reaction network subject to a flow of chemicals show that the system undergoes a transition from a stationary to an intermittent reaction phase when the flow rate is decreased. In the intermittent reaction phase, two temporal regimes with active and halted reactions alternate. The number frequency of reaction events at e...

  18. Catalytic Ignition and Upstream Reaction Propagation in a Platinum Tube

    Science.gov (United States)

    Struk, P. M.; Dietrich, D. L.; Mellish, B. P.; Miller, F. J.; T'ien, J. S.

    2007-01-01

    A challenge for catalytic combustion in monolithic reactors at elevated temperatures is the start-up or "light-off" from a cold initial condition. In this work, we demonstrate a concept called "back-end catalytic ignition that potentially can be utilized in the light-off of catalytic monoliths. An external downstream flame or Joule heating raises the temperature of a small portion of the catalyst near the outlet initiating a localized catalytic reaction that propagates upstream heating the entire channel. This work uses a transient numerical model to demonstrate "back-end" ignition within a single channel which can characterize the overall performance of a monolith. The paper presents comparisons to an experiment using a single non-adiabatic channel but the concept can be extended to the adiabatic monolith case. In the model, the time scales associated with solid heat-up are typically several orders of magnitude larger than the gas-phase and chemical kinetic time-scales. Therefore, the model assumes a quasi-steady gas-phase with respect to a transient solid. The gas phase is one-dimensional. Appropriate correlations, however, account for heat and mass transfer in a direction perpendicular to the flow. The thermally-thin solid includes axial conduction. The gas phase, however, does not include axial conduction due to the high Peclet number flows. The model includes both detailed gas-phase and catalytic surface reactions. The experiment utilizes a pure platinum circular channel oriented horizontally though which a CO/O2 mixture (equivalence ratios ranging from 0.6 to 0.9) flows at 2 m/s.

  19. 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.

  20. Recent developments in research on catalytic reaction networks

    Directory of Open Access Journals (Sweden)

    Roberto Serra

    2013-09-01

    Full Text Available Over the last years, analyses performed on a stochastic model of catalytic reaction networks have provided some indications about the reasons why wet-lab experiments hardly ever comply with the phase transition typically predicted by theoretical models with regard to the emergence of collectively self-replicating sets of molecule (also defined as autocatalytic sets, ACSs, a phenomenon that is often observed in nature and that is supposed to have played a major role in the emergence of the primitive forms of life. The model at issue has allowed to reveal that the emerging ACSs are characterized by a general dynamical fragility, which might explain the difficulty to observe them in lab experiments. In this work, the main results of the various analyses are reviewed, with particular regard to the factors able to affect the generic properties of catalytic reactions network, for what concerns, not only the probability of ACSs to be observed, but also the overall activity of the system, in terms of production of new species, reactions and matter.

  1. Kinetics of catalytic reactions-solutions manual

    CERN Document Server

    Vannice, M Albert

    2008-01-01

    Including countless exercises and worked examples, this advanced reference work and textbook will be extremely useful for the work of many industrial scientists. It teaches readers to design kinetic experiments involving heterogeneous catalysts, to characterize these catalysts, to acquire rate data, to find heat and mass transfer limitations in these data, to select reaction models, to derive rate expressions based on these models, and to assess the consistency of these rate equations.

  2. 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.

  3. Atmospheric Pressure Microwave Assisted Heterogeneous Catalytic Reactions

    Directory of Open Access Journals (Sweden)

    Farid Chemat

    2007-07-01

    Full Text Available The purpose of the study was to investigate microwave selective heatingphenomena and their impact on heterogeneous chemical reactions. We also present a toolwhich will help microwave chemists to answer to such questions as “My reaction yields90% after 7 days at reflux; is it possible to obtain the same yield after a few minutes undermicrowaves?” and to have an approximation of their reactions when conducted undermicrowaves with different heterogeneous procedures. This model predicting reactionkinetics and yields under microwave heating is based on the Arrhenius equation, inagreement with experimental data and procedures.

  4. Identifying systematic DFT errors in catalytic reactions

    DEFF Research Database (Denmark)

    Christensen, Rune; Hansen, Heine Anton; Vegge, Tejs

    2015-01-01

    Using CO2 reduction reactions as examples, we present a widely applicable method for identifying the main source of errors in density functional theory (DFT) calculations. The method has broad applications for error correction in DFT calculations in general, as it relies on the dependence of the...... applied exchange–correlation functional on the reaction energies rather than on errors versus the experimental data. As a result, improved energy corrections can now be determined for both gas phase and adsorbed reaction species, particularly interesting within heterogeneous catalysis. We show that for...... the CO2 reduction reactions, the main source of error is associated with the C[double bond, length as m-dash]O bonds and not the typically energy corrected OCO backbone....

  5. Catalytic asymmetric umpolung reactions of imines.

    Science.gov (United States)

    Wu, Yongwei; Hu, Lin; Li, Zhe; Deng, Li

    2015-07-23

    The carbon-nitrogen double bonds in imines are fundamentally important functional groups in organic chemistry. This is largely due to the fact that imines act as electrophiles towards carbon nucleophiles in reactions that form carbon-carbon bonds, thereby serving as one of the most widely used precursors for the formation of amines in both synthetic and biosynthetic settings. If the carbon atom of the imine could be rendered electron-rich, the imine could react as a nucleophile instead of as an electrophile. Such a reversal in the electronic characteristics of the imine functionality would facilitate the development of new chemical transformations that convert imines into amines via carbon-carbon bond-forming reactions with carbon electrophiles, thereby creating new opportunities for the efficient synthesis of amines. The development of asymmetric umpolung reactions of imines (in which the imines act as nucleophiles) remains uncharted territory, in spite of the far-reaching impact such reactions would have in organic synthesis. Here we report the discovery and development of new chiral phase-transfer catalysts that promote the highly efficient asymmetric umpolung reactions of imines with the carbon electrophile enals. These catalysts mediate the deprotonation of imines and direct the 2-azaallyl anions thus formed to react with enals in a highly chemoselective, regioselective, diastereoselective and enantioselective fashion. The reaction tolerates a broad range of imines and enals, and can be carried out in high yield with as little as 0.01 mole per cent catalyst with a moisture- and air-tolerant operational protocol. These umpolung reactions provide a conceptually new and practical approach to chiral amino compounds. PMID:26201597

  6. Tracer investigations of catalytic reactions of hydrocarbons

    International Nuclear Information System (INIS)

    Tracer techniques with 14C-labelled compounds were used to investigate the isomerization of C8-aromatics and reforming of light gasoline. The investigations aimed at determining the selectivity of newly developed catalysts and at elucidating the reaction mechanisms. The appropriate tracer methods are briefly discussed including their theoretical fundamentals

  7. Heterogeneous-catalytic redox reactions in nitrate - formate systems

    International Nuclear Information System (INIS)

    It was found that an intensive destruction of various organic and mineral substances - usual components of aqueous waste solutions (oxalic acid, complexones, urea, hydrazine, ammonium nitrate, etc.) takes place under the conditions of catalytic denitration. Kinetics and mechanisms of urea and ammonium nitrate decomposition in the system HNO3 - HCOOH - Pt/SiO2 are comprehensively investigated. The behaviour of uranium, neptunium and plutonium under the conditions of catalytic denitration is studied. It is shown, that under the certain conditions the formic acid is an effective reducer of the uranium (VI), neptunium (VI, V) and plutonium (VI, IV) ions. Kinetics of heterogeneous-catalytic red-ox reactions of uranium (VI), neptunium (VI, V) and plutonium (VI, IV) with formic acid are investigated. The mechanisms of the appropriate reactions are evaluated. (authors)

  8. 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.

  9. [Lipases in catalytic reactions of organic chemistry].

    Science.gov (United States)

    Bezborodov, A M; Zagustina, N A

    2014-01-01

    Aspects of enzymatic catalysis in lipase-catalyzed reactions of organic synthesis are discussed in the review. The data on modern methods of protein engineering and enzyme modification allowing a broader range of used substrates are briefly summarized. The application of lipase in the preparation of pharmaceuticals and agrochemicals containing no inactive enantiomers and in the synthesis of secondary alcohol enantiomers and optically active amides is demonstrated. The subject of lipase involvement in the C-C bond formation in the Michael reaction is discussed. Data on the enzymatic synthesis of construction materials--polyesters, siloxanes, etc.--are presented. Examples demonstrating the application of lipase enzymatic catalysis in industry are given. PMID:25707112

  10. Catalytic Asymmetric Umpolung Reactions of Imines

    OpenAIRE

    Wu, Yongwei; Hu, Lin; Li, Zhe; Deng, Li

    2015-01-01

    Imines, carbon-nitrogen double bonds, are fundamentally important functional groups in organic chemistry. This is largely due to the fact that imines act as electrophiles in C–C bond forming reactions towards carbon nucleophiles, thereby serving one of the most widely used precursors for the formation of amines in both synthetic and biosynthetic settings. 1–5 If the carbon atom of the imine could be rendered electron-rich, the imine could react as a nucleophile instead of as an electrophile. ...

  11. Modular, Catalytic Enantioselective Construction of Quaternary Carbon Stereocenters by Sequential Cross-Coupling Reactions.

    Science.gov (United States)

    Potter, Bowman; Edelstein, Emma K; Morken, James P

    2016-07-01

    The catalytic Suzuki-Miyaura cross-coupling with chiral γ,γ-disubstituted allylboronates in the presence of RuPhos ligand occurs with high regioselectivity and enantiospecificity, furnishing nonracemic compounds with quaternary centers. Mechanistic experiments suggest that the reaction occurs by transmetalation with allyl migration, followed by rapid reductive elimination. PMID:27310927

  12. Stereodivergent catalytic doubly diastereoselective nitroaldol reactions using heterobimetallic complexes.

    Science.gov (United States)

    Sohtome, Yoshihiro; Kato, Yuko; Handa, Shinya; Aoyama, Naohiro; Nagawa, Keita; Matsunaga, Shigeki; Shibasaki, Masakatsu

    2008-06-01

    Stereodivergent construction of three contiguous stereocenters in catalytic doubly diastereoselective nitroaldol reactions of alpha-chiral aldehydes with nitroacetaldehyde dimethyl acetal using two types of heterobimetallic catalysts is described. A La-Li-BINOL (LLB) catalyst afforded anti,syn-nitroaldol products in >20:1-14:1 selectivity, and a Pd/La/Schiff base catalyst afforded complimentary syn,syn-nitroaldol products in 10:1-5:1 selectivity. PMID:18465868

  13. Chemical selforganization of composite catalysts during catalytic reactions

    Energy Technology Data Exchange (ETDEWEB)

    Imbihl, Ronald, E-mail: imbihl@pci.uni-hannover.de [Institut fuer Physikalische Chemie und Elektrochemie, Leibniz-Universitaet Hannover, Callinstrasse 3-3a, D-30167 Hannover (Germany)

    2012-10-15

    Highlights: Black-Right-Pointing-Pointer Selforganization of composite catalysts under reaction conditions. Black-Right-Pointing-Pointer Reactive phase separation causes demixing of catalysts. Black-Right-Pointing-Pointer Condensation patterns in supported oxide catalysts. -- Abstract: Recent progress in the study of selforganization phenomena in catalytic reactions on multi-component surfaces is reviewed. As chemically more complex systems a Rh(1 1 1) surface with ultra-thin vanadium oxide layers ({theta}{sub V} < 0.5 MLE) and a bimetallic Rh(1 1 1)/Ni surface, both subjected to the H{sub 2} + O{sub 2} reaction, were chosen. Applying spatially resolving methods in situ, it is shown that under reaction conditions a reversible redistribution of the components of the catalyst occurs. The redistribution processes are essentially driven by the different chemical affinities of the components to reacting species.

  14. Preparation of Pt-Ru hydrophobic catalysts and catalytic activities for liquid phase catalytic exchange reaction

    International Nuclear Information System (INIS)

    Pt/C and Pt-Ru/C catalysts with different ratios of Pt to Ru were synthesized, using ethylene glycol as both the dispersant and reducing agent at 1-2 MPa by microwave-assisted method. The catalysts were characterized by XRD, TEM and XPS. The mean particle sizes of the Pt/C and Pt-Ru/C catalysts were 1.9-2.0 nm. Pt and Ru existed as Pt(0), Pt(II), Pt(IV), Ru(0) and Ru(IV) for Pt-Ru/C catalysts, respectively. The face-centered cubic structure of the active mental particles would be changed upon the addition of Ru gradually. Then polytetrafluoroethylene and carbon-supported Pt and Pt-Ru catalysts were supported on foamed nickel to obtain hydrophobic catalysts. The catalytic activity was increased for liquid phase catalytic exchange (LPCE) when uniform Pt based hydrophobic catalysts was mixed into appropriate Ru. Hydrogen isotope exchange reaction occurs between hydration layer(H2O)nH+(ads)(n≥2) and D atoms due to intact water molecules being on Pt surface for LPCE. Water molecules have a tendency to dissociate to OH(ads) and H(ads) on metal Ru surface, and there is the other reaction path for Pt-Ru binary catalysts, which is probably the main reason of the increase of the catalytic activity of the hydrophobic Pt-Ru catalyst. (authors)

  15. Developing a Practical Chiral Toolbox for Asymmetric Catalytic Reactions

    Institute of Scientific and Technical Information of China (English)

    ZHANG; XuMu

    2001-01-01

    Chiral Quest's Toolbox Approach: During the last several decades, chemists have made major progress in discovering man-made catalysts to perform challenging asymmetric transformations. However, there is no universal chiral ligand or catalyst for solving problems in enantioselective transformations. The focus of Chiral Quest's research is to develop a useful chiral toolbox for strategically important asymmetric catalytic reactions by inventing a diverse set of novel chiral ligands and combining them with transition metals as effective enantioselective catalysts. The toolbox approach addresses significant problems in organic stereochemistry and has resulted in practical methods for the synthesis of chiral pharmaceuticals and agrochemicals  ……

  16. Developing a Practical Chiral Toolbox for Asymmetric Catalytic Reactions

    Institute of Scientific and Technical Information of China (English)

    ZHANG XuMu

    2001-01-01

    @@ Chiral Quest's Toolbox Approach: During the last several decades, chemists have made major progress in discovering man-made catalysts to perform challenging asymmetric transformations. However, there is no universal chiral ligand or catalyst for solving problems in enantioselective transformations. The focus of Chiral Quest's research is to develop a useful chiral toolbox for strategically important asymmetric catalytic reactions by inventing a diverse set of novel chiral ligands and combining them with transition metals as effective enantioselective catalysts. The toolbox approach addresses significant problems in organic stereochemistry and has resulted in practical methods for the synthesis of chiral pharmaceuticals and agrochemicals

  17. Orion EFT-1 Catalytic Tile Experiment Overview and Flight Measurements

    Science.gov (United States)

    Salazar, Giovanni; Amar, Adam; Hyatt, Andrew; Rezin, Marc D.

    2016-01-01

    This paper describes the design and results of a surface catalysis flight experiment flown on the Orion Multipurpose Crew Vehicle during Exploration Flight Test 1 (EFT1). Similar to previous Space Shuttle catalytic tile experiments, the present test consisted of a highly catalytic coating applied to an instrumented TPS tile. However, the present catalytic tile experiment contained significantly more instrumentation in order to better resolve the heating overshoot caused by the change in surface catalytic efficiency at the interface between two distinct materials. In addition to collecting data with unprecedented spatial resolution of the "overshoot" phenomenon, the experiment was also designed to prove if such a catalytic overshoot would be seen in turbulent flow in high enthalpy regimes. A detailed discussion of the results obtained during EFT1 is presented, as well as the challenges associated with data interpretation of this experiment. Results of material testing carried out in support of this flight experiment are also shown. Finally, an inverse heat conduction technique is employed to reconstruct the flight environments at locations upstream and along the catalytic coating. The data and analysis presented in this work will greatly contribute to our understanding of the catalytic "overshoot" phenomenon, and have a significant impact on the design of future spacecraft.

  18. 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.

  19. Catalytic and Gas-Solid Reactions Involving HCN over Limestone

    DEFF Research Database (Denmark)

    Jensen, Anker; Johnsson, Jan Erik; Dam-Johansen, Kim

    1997-01-01

    In coal-fired combustion systems solid calcium species may be present as ash components or limestone added to the combustion chamber. In this study heterogeneous reactions involving HCN over seven different limestones were investigated in a laboratory fixed-bed quartz reactor at 873-1,173 K....... Calcined limestone is an effective catalyst for oxidation of HCN. Under conditions with complete conversion of HCN at O-2 concentrations above about 5,000 ppmv the selectivity for formation of NO and N2O is 50-70% and below 5%, respectively. Nitric oxide can be reduced by HCN to N-2 in the absence of O-2...... decreases with increasing degree of sulfation. Simultaneously the selectivity for formation of NO decreases while that for N2O increases. The catalytic activity of sulfated limestone increases with decreasing SO2 concentration indicating a competition between SO2 and HCN for sites on the surface. The...

  20. 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

  1. Engineering Metallic Nanoparticles for Enhancing and Probing Catalytic Reactions.

    Science.gov (United States)

    Collins, Gillian; Holmes, Justin D

    2016-07-01

    Recent developments in tailoring the structural and chemical properties of colloidal metal nanoparticles (NPs) have led to significant enhancements in catalyst performance. Controllable colloidal synthesis has also allowed tailor-made NPs to serve as mechanistic probes for catalytic processes. The innovative use of colloidal NPs to gain fundamental insights into catalytic function will be highlighted across a variety of catalytic and electrocatalytic applications. The engineering of future heterogenous catalysts is also moving beyond size, shape and composition considerations. Advancements in understanding structure-property relationships have enabled incorporation of complex features such as tuning surface strain to influence the behavior of catalytic NPs. Exploiting plasmonic properties and altering colloidal surface chemistry through functionalization are also emerging as important areas for rational design of catalytic NPs. This news article will highlight the key developments and challenges to the future design of catalytic NPs. PMID:26823380

  2. Growth states of catalytic reaction networks exhibiting energy metabolism

    Science.gov (United States)

    Kondo, Yohei; Kaneko, Kunihiko

    2011-07-01

    All cells derive nutrition by absorbing some chemical and energy resources from the environment; these resources are used by the cells to reproduce the chemicals within them, which in turn leads to an increase in their volume. In this study we introduce a protocell model exhibiting catalytic reaction dynamics, energy metabolism, and cell growth. Results of extensive simulations of this model show the existence of four phases with regard to the rates of both the influx of resources and cell growth. These phases include an active phase with high influx and high growth rates, an inefficient phase with high influx but low growth rates, a quasistatic phase with low influx and low growth rates, and a death phase with negative growth rate. A mean field model well explains the transition among these phases as bifurcations. The statistical distribution of the active phase is characterized by a power law, and that of the inefficient phase is characterized by a nearly equilibrium distribution. We also discuss the relevance of the results of this study to distinct states in the existing cells.

  3. Developing soft X-ray spectroscopy for in situ characterization of nanocatalysts in catalytic reactions

    International Nuclear Information System (INIS)

    Understanding the mechanisms of catalytic and reactions calls for in situ/operando spectroscopic characterization. Here we report the developments of in situ reaction cells at the Advanced Light Source for soft X-ray spectroscopic studies of nanoparticle catalysts during the catalytic reactions. The operation of these various cells and their capabilities are illustrated with examples from the studies of Co-based nanocatalysts

  4. Modelling of Surface Catalytic Reaction Systems using the Concept of Extents

    OpenAIRE

    Chhabra, Vibhuti

    2014-01-01

    Gas-solid catalytic reaction systems depend on a combination of several dynamic eects, such as mass transfer, chemisorption and surface reactions taking place simultaneously. In this master thesis, the extension of the method of extent-based model identication is proposed for catalytic reaction systems which involves the transformation of the number of moles in the gas and solid phases into decoupled state variables called (vessel) extents. This transformation computes extents of inlet, outle...

  5. 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.

  6. Artificial reaction coordinate "tunneling" in free-energy calculations: the catalytic reaction of RNase H.

    Science.gov (United States)

    Rosta, Edina; Woodcock, H Lee; Brooks, Bernard R; Hummer, Gerhard

    2009-08-01

    We describe a method for the systematic improvement of reaction coordinates in quantum mechanical/molecular mechanical (QM/MM) calculations of reaction free-energy profiles. In umbrella-sampling free-energy calculations, a biasing potential acting on a chosen reaction coordinate is used to sample the system in reactant, product, and transition states. Sharp, nearly discontinuous changes along the resulting reaction path are used to identify coordinates that are relevant for the reaction but not properly sampled. These degrees of freedom are then included in an extended reaction coordinate. The general formalism is illustrated for the catalytic cleavage of the RNA backbone of an RNA/DNA hybrid duplex by the RNase H enzyme of Bacillus halodurans. We find that in the initial attack of the phosphate diester by water, the oxygen-phosphorus distances alone are not sufficient as reaction coordinates, resulting in substantial hysteresis in the proton degrees of freedom and a barrier that is too low (approximately 10 kcal/mol). If the proton degrees of freedom are included in an extended reaction coordinate, we obtain a barrier of 21.6 kcal/mol consistent with the experimental rates. As the barrier is approached, the attacking water molecule transfers one of its protons to the O1P oxygen of the phosphate group. At the barrier top, the resulting hydroxide ion forms a penta-coordinated phosphate intermediate. The method used to identify important degrees of freedom, and the procedure to optimize the reaction coordinate are general and should be useful both in classical and in QM/MM free-energy calculations. PMID:19462398

  7. Artificial reaction coordinate “tunneling” in free energy calculations: the catalytic reaction of RNase H

    Science.gov (United States)

    Rosta, Edina; Woodcock, H. Lee; Brooks, Bernard R.; Hummer, Gerhard

    2011-01-01

    We describe a method for the systematic improvement of reaction coordinates in quantum mechanical / molecular mechanical (QM/MM) calculations of reaction free energy profiles. In umbrella-sampling free energy calculations, a biasing potential acting on a chosen reaction coordinate is used to sample the system in reactant, product, and transition states. Sharp, nearly discontinuous changes along the resulting reaction path are used to identify coordinates that are relevant for the reaction but not properly sampled. These degrees of freedom are then included in an extended reaction coordinate. The general formalism is illustrated for the catalytic cleavage of the RNA backbone of an RNA/DNA hybrid duplex by the RNase H enzyme of bacillus halodurans. We find that in the initial attack of the phosphate diester by water, the oxygen-phosphorus distances alone are not sufficient as reaction coordinates, resulting in substantial hysteresis in the proton degrees of freedom and a barrier that is too low (~10 kcal/mol). If the proton degrees of freedom are included in an extended reaction coordinate, we obtain a barrier of 21.6 kcal/mol consistent with the experimental rates. As the barrier is approached, the attacking water molecule transfers one of its protons to the O1P oxygen of the phosphate group. At the barrier top, the resulting hydroxide ion forms a penta-coordinated phosphate intermediate. The method used to identify important degrees of freedom, and the procedure to optimize the reaction coordinate are general and should be useful both in classical and in QM/MM free energy calculations. PMID:19462398

  8. Reaction pathways for catalytic gas-phase oxidation of glycerol over mixed metal oxides

    Energy Technology Data Exchange (ETDEWEB)

    Suprun, W.; Glaeser, R.; Papp, H. [Leipzig Univ. (Germany). Inst. of Chemical Technology

    2011-07-01

    Glycerol as a main by-product from bio-diesel manufacture is a cheap raw material with large potential for chemical or biochemical transformations to value-added C3-chemicals. One possible way of glycerol utilization involves its catalytic oxidation to acrylic acid as an alternative to petrochemical routes. However, this catalytic conversion exhibits various problems such as harsh reaction conditions, severe catalyst coking and large amounts of undesired by-products. In this study, the reaction pathways for gas-phase conversion of glycerol over transition metal oxides (Mo, V und W) supported on TiO{sub 2} and SiO{sub 2} were investigated by two methods: (i) steady state experiments of glycerol oxidation and possible reactions intermediates, i.e., acrolein, 3-hydroxy propionaldehyde and acetaldehyde, and (ii) temperature-programmed surface reaction (TPSR) studies of glycerol conversion in the presence and in the absence of gas-phase oxygen. It is shown that the supported W-, V and Mo-oxides possess an ability to catalyze the oxidation of glycerol to acrylic acid. These investigations allowed us to gain a deeper insight into the reaction mechanism. Thus, based on the obtained results, three possible reactions pathways for the selective oxidation of glycerol to acrylic acid on the transition metal-containing catalysts are proposed. The major pathways in presence of molecular oxygen are a fast successive destructive oxidation of glycerol to CO{sub x} and the dehydration of glycerol to acrolein which is a rate-limiting step. (orig.)

  9. Catalytic reactor for promoting a chemical reaction on a fluid passing therethrough

    Science.gov (United States)

    Roychoudhury, Subir (Inventor); Pfefferle, William C. (Inventor)

    2001-01-01

    A catalytic reactor with an auxiliary heating structure for raising the temperature of a fluid passing therethrough whereby the catalytic reaction is promoted. The invention is a apparatus employing multiple electrical heating elements electrically isolated from one another by insulators that are an integral part of the flow path. The invention provides step heating of a fluid as the fluid passes through the reactor.

  10. A study on the photo catalytic decomposition reactions of organics dissolved in water (II)

    International Nuclear Information System (INIS)

    Experiments on aqueous TiO2 photo catalytic reaction of nitrogen containing organic compounds such as ethylamine, phenylhydrazine, pyridine, urea and EDTA were carried out. Based on the values calculated for the distribution of ionic species and atomic charge, the characteristics of their photo catalytic decomposition were estimated. It was shown that the decomposition characteristics was linearly proportional to nitrogen atomic charge value. On the other hand, the effects of aqueous pH, oxygen content and concentration on the TiO2 photo catalytic characteristics of EDTA, EDTA-Cu(II) and EDTA-Fe(III) were experimentally investigated. All EDTA systems were decomposed better in the pH range of 2.5-3.0 and with more dissolved oxygen. These results could be applied to construction of a process for removal of organic impurities dissolved in a source of system water, or for treatment of EDTA-containing liquid waste produced by a chemical cleaning in the domestic NPPs. (author)

  11. A study on the photo catalytic decomposition reactions of organics dissolved in water (II)

    Energy Technology Data Exchange (ETDEWEB)

    Sung, K.W.; Na, J. W.; Cho, Y. H.; Chung, H. H

    2000-01-01

    Experiments on aqueous TiO{sub 2} photo catalytic reaction of nitrogen containing organic compounds such as ethylamine, phenylhydrazine, pyridine, urea and EDTA were carried out. Based on the values calculated for the distribution of ionic species and atomic charge, the characteristics of their photo catalytic decomposition were estimated. It was shown that the decomposition characteristics was linearly proportional to nitrogen atomic charge value. On the other hand, the effects of aqueous pH, oxygen content and concentration on the TiO{sub 2} photo catalytic characteristics of EDTA, EDTA-Cu(II) and EDTA-Fe(III) were experimentally investigated. All EDTA systems were decomposed better in the pH range of 2.5-3.0 and with more dissolved oxygen. These results could be applied to construction of a process for removal of organic impurities dissolved in a source of system water, or for treatment of EDTA-containing liquid waste produced by a chemical cleaning in the domestic NPPs. (author)

  12. A general catalytic reaction sequence to access alkaloid-inspired indole polycycles.

    Science.gov (United States)

    Danda, Adithi; Kumar, Kamal; Waldmann, Herbert

    2015-05-01

    A catalytic two-step reaction sequence was developed to access a range of complex heterocyclic frameworks based on biorelevant indole/oxindole scaffolds. The reaction sequence includes catalytic Pictet-Spengler cyclization followed by Au(I) catalyzed intramolecular hydroamination of acetylenes. A related cascade polycyclization of a designed β-carboline embodying a 1,5-enyne group yields the analogues of the alkaloid harmicine. PMID:25846800

  13. 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.

  14. Kinetic and catalytic performance of a BI-porous composite material in catalytic cracking and isomerisation reactions

    KAUST Repository

    Al-Khattaf, S.

    2012-01-10

    Catalytic behaviour of pure zeolite ZSM-5 and a bi-porous composite material (BCM) were investigated in transformation of m-xylene, while zeolite HY and the bi-porous composite were used in the cracking of 1,3,5-triisopropylbenzene (TIPB). The micro/mesoporous material was used to understand the effect of the presence of mesopores on these reactions. Various characterisation techniques, that is, XRD, SEM, TGA, FT-IR and nitrogen sorption measurements were applied for complete characterisation of the catalysts. Catalytic tests using CREC riser simulator showed that the micro/mesoporous composite catalyst exhibited higher catalytic activity as compared with the conventional microporous ZSM-5 and HY zeolite for transformation of m-xylene and for the catalytic cracking of TIPB, respectively. The outstanding catalytic reactivity of m-xylene and TIPB molecules were mainly attributed to the easier access of active sites provided by the mesopores. Apparent activation energies for the disappearance of m-xylene and TIPB over all catalysts were found to decrease in the order: EBCM>EZSM-5 and EBCM>EHY, respectively. © 2012 Canadian Society for Chemical Engineering.

  15. 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.

  16. (Gold core) at (ceria shell) nanostructures for plasmon-enhanced catalytic reactions under visible light

    KAUST Repository

    Wang, Jianfang

    2014-08-26

    Driving catalytic reactions with sunlight is an excellent example of sustainable chemistry. A prerequisite of solar-driven catalytic reactions is the development of photocatalysts with high solar-harvesting efficiencies and catalytic activities. Herein, we describe a general approach for uniformly coating ceria on monometallic and bimetallic nanocrystals through heterogeneous nucleation and growth. The method allows for control of the shape, size, and type of the metal core as well as the thickness of the ceria shell. The plasmon shifts of the Au@CeO2 nanostructures resulting from the switching between Ce(IV) and Ce(III) are observed. The selective oxidation of benzyl alcohol to benzaldehyde, one of the fundamental reactions for organic synthesis, performed under both broad-band and monochromatic light, demonstrates the visible-light-driven catalytic activity and reveals the synergistic effect on the enhanced catalysis of the Au@CeO2 nanostructures. © 2014 American Chemical Society.

  17. STUDIES ON THE CATALYTIC REACTION OF NITROGEN OXIDE ON METAL MODIFIED ACTIVATED CARBON FIBERS

    Institute of Scientific and Technical Information of China (English)

    FU Ruowen; DU Xiuying; LIN Yuansheng; XU Hao; HU Yiongjun

    2003-01-01

    The catalytic reaction of NO with CO and decomposition of NO over metal modified ACFs were investigated and compared with other carriers supported catalysts. It is demonstrated that Pd/ACF and Pd/Cu/ACF have high catalytic activity for the reaction of NO/CO, while Pt/ACF.Pt/Cu/ACF and Co/Cu/ACF have very Iow catalytic activity in similar circumstance. Pd-modified ACF possesses high catalytic decomposition of NO at 300 ℃. Pd/CB and Pd/GAC present good catalytic decomposition ability for NO only at low flowrate. Pd/G, Pd/ZMS and Pd/A however, do not show any catalytic activity for NO decomposition even at 400 ℃. Catalytic temperature, NO flowrate and loading of metal components affect the decomposition rate of NO. The coexistence of Cu with Pd on Cu/Pd/ACF leads to crystalline of palladium to more unperfected so as to that increase the catalytic activity.

  18. SpaciMS: spatial and temporal operando resolution of reactions within catalytic monoliths

    Energy Technology Data Exchange (ETDEWEB)

    Sa, Jacinto [Queen' s University, Belfast; Fernandes, Daniel [University of Aveiro, Portugal; Aiouache, Farid [Queen' s University, Belfast; Goguet, Alexandre [Queen' s University, Belfast; Hardacdre, Christopher [Queen' s University, Belfast; Lundie, David [Hiden Analytical Ltd; Naeem, Wasif [Queen' s University, Belfast; Partridge Jr, William P [ORNL; Stere, Cristina [Queen' s University, Belfast

    2010-01-01

    Monolithic catalysts are widely used as structured catalysts, especially in the abatement of pollutants. Probing what happens inside these monoliths during operation is, therefore, vital for modelling and prediction of the catalyst behavior. SpaciMS is a spatially resolved capillary-inlet mass spectroscopy system allowing for the generation of spatially resolved maps of the reactions within monoliths. In this study SpaciMS results combined with 3D CFD modelling demonstrate that SpaciMS is a highly sensitive and minimally invasive technique that can provide reaction maps as well as catalytic temporal behavior. Herein we illustrate this by examining kinetic oscillations during a CO oxidation reaction over a Pt/Rh on alumina catalyst supported on a cordierite monolith. These oscillations were only observed within the monolith by SpaciMS between 30 and 90% CO conversion. Equivalent experiments performed in a plug-flow reactor using this catalyst in a crushed form over a similar range of reaction conditions did not display any oscillations demonstrating the importance of intra monolith analysis. This work demonstrates that the SpaciMS offers an accurate and comprehensive picture of structured catalysts under operation.

  19. Controlling Catalytic Selectivity via Adsorbate Orientation on the Surface: From Furfural Deoxygenation to Reactions of Epoxides.

    Science.gov (United States)

    Pang, Simon H; Medlin, J Will

    2015-04-16

    Specificity to desired reaction products is the key challenge in designing solid catalysts for reactions involving addition or removal of oxygen to/from organic reactants. This challenge is especially acute for reactions involving multifunctional compounds such as biomass-derived aromatic molecules (e.g., furfural) and functional epoxides (e.g., 1-epoxy-3-butene). Recent surface-level studies have shown that there is a relationship between adsorbate surface orientation and reaction selectivity in the hydrogenation pathways of aromatic oxygenates and the ring-opening or ring-closing pathways of epoxides. Control of the orientation of reaction intermediates on catalytic surfaces by modifying the surface or near-surface environment has been shown to be a promising method of affecting catalytic selectivity for reactions of multifunctional molecules. In this Perspective, we review recent model studies aimed at understanding the surface chemistry for these reactions and studies that utilize this insight to rationally design supported catalysts. PMID:26263134

  20. A consistent reaction scheme for the selective catalytic reduction of nitrogen oxides with ammonia

    DEFF Research Database (Denmark)

    Janssens, Ton V.W.; Falsig, Hanne; Lundegaard, Lars Fahl;

    2015-01-01

    For the first time, the standard and fast selective catalytic reduction of NO by NH3 are described in a complete catalytic cycle, that is able to produce the correct stoichiometry, while only allowing adsorption and desorption of stable molecules. The standard SCR reaction is a coupling of the ac......For the first time, the standard and fast selective catalytic reduction of NO by NH3 are described in a complete catalytic cycle, that is able to produce the correct stoichiometry, while only allowing adsorption and desorption of stable molecules. The standard SCR reaction is a coupling...... of the activation of NO by O2 with the fast SCR reaction, enabled by the release of NO2. According to the scheme, the SCR reaction can be divided in an oxidation of the catalyst by NO + O2 and a reduction by NO + NH3; these steps together constitute a complete catalytic cycle. Furthermore both NO and NH3...... spectroscopy (FTIR). A consequence of the reaction scheme is that all intermediates in fast SCR are also part of the standard SCR cycle. The calculated activation energy by density functional theory (DFT) indicates that the oxidation of an NO molecule by O2 to a bidentate nitrate ligand is rate determining...

  1. Aligned carbon nanotube with electro-catalytic activity for oxygen reduction reaction

    Science.gov (United States)

    Liu, Di-Jia; Yang, Junbing; Wang, Xiaoping

    2010-08-03

    A catalyst for an electro-chemical oxygen reduction reaction (ORR) of a bundle of longitudinally aligned carbon nanotubes having a catalytically active transition metal incorporated longitudinally in said nanotubes. A method of making an electro-chemical catalyst for an oxygen reduction reaction (ORR) having a bundle of longitudinally aligned carbon nanotubes with a catalytically active transition metal incorporated throughout the nanotubes, where a substrate is in a first reaction zone, and a combination selected from one or more of a hydrocarbon and an organometallic compound containing an catalytically active transition metal and a nitrogen containing compound and an inert gas and a reducing gas is introduced into the first reaction zone which is maintained at a first reaction temperature for a time sufficient to vaporize material therein. The vaporized material is then introduced to a second reaction zone maintained at a second reaction temperature for a time sufficient to grow longitudinally aligned carbon nanotubes over the substrate with a catalytically active transition metal incorporated throughout the nanotubes.

  2. High-pressure catalytic reactions over single-crystal metal surfaces

    Science.gov (United States)

    Rodriguez, JoséA.; Wayne Goodman, D.

    1991-11-01

    Studies dealing with high-pressure catalytic reactions over single-crystal surfaces are reviewed. The coupling of an apparatus for the measurement of reaction kinetics at elevated pressures with an ultrahigh vacuum system for surface analysis allows detailed study of structure sensitivity, the effects of promoters and inhibitors on catalytic activity, and, in certain cases, identification of reaction intermediates by post-reaction surface analysis. Examples are provided which demonstrate the relevance of single-crystal studies for modeling the behaviour of high-surface-area supported catalysts. Studies of CO methanation and CO oxidation over single-crystal surfaces provide convincing evidence that these reactions are structure insensitive. For structure-sensitive reactions (ammonia synthesis, alkane hydrogenolysis, alkane isomerization, water-gas shift reaction, etc.) model single-crystal studies allow correlations to be established between surface structure and catalytic activity. The effects of both electronegative (S and P) and electropositive (alkali metals) impurities upon the catalytic activity of metal single crystals for ammonia synthesis, CO methanation, alkane hydrogenolysis, ethylene epoxidation and water-gas shift are discussed. The roles of "ensemble" and "ligand" effects in bimetallic catalysts are examined in light of data obtained using surfaces prepared by vapor-depositing one metal onto a crystal face of a dissimilar metal.

  3. Process of forming catalytic surfaces for wet oxidation reactions

    Science.gov (United States)

    Jagow, R. B. (Inventor)

    1977-01-01

    A wet oxidation process was developed for oxidizing waste materials, comprising dissolved ruthenium salt in a reactant feed stream containing the waste materials. The feed stream is introduced into a reactor, and the reactor contents are then raised to an elevated temperature to effect deposition of a catalytic surface of ruthenium black on the interior walls of the reactor. The feed stream is then maintained in the reactor for a period of time sufficient to effect at least partial oxidation of the waste materials.

  4. Photocatalytic Water-Splitting Reaction from Catalytic and Kinetic Perspectives

    KAUST Repository

    Hisatomi, Takashi

    2014-10-16

    Abstract: Some particulate semiconductors loaded with nanoparticulate catalysts exhibit photocatalytic activity for the water-splitting reaction. The photocatalysis is distinct from the thermal catalysis because photocatalysis involves photophysical processes in particulate semiconductors. This review article presents a brief introduction to photocatalysis, followed by kinetic aspects of the photocatalytic water-splitting reaction.Graphical Abstract: [Figure not available: see fulltext.

  5. 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.

  6. Novel monolithic electrochemically promoted catalytic reactor for environmentally important reactions

    Energy Technology Data Exchange (ETDEWEB)

    Balomenou, S.; Tsiplakides, D.; Katsaounis, A.; Vayenas, C.G. [Department of Chemical Engineering, University of Patras, Caratheodory 1 St., GR-26504 Patras (Greece); Thiemann-Handler, S.; Cramer, B. [Robert Bosch GmbH Stuttgart, FV/FLC, PF 10 60 50, 70 049 Stuttgart (Germany); Foti, G.; Comninellis, Ch. [Institute of Chemical Sciences and Engineering, Swiss Federal Institute of Technology, CH-1015 Lausanne (Switzerland)

    2004-09-28

    A novel dismantlable monolithic-type electrochemically promoted catalytic reactor and 'smart' sensor-catalytic reactor unit has been constructed and tested for hydrocarbon oxidation and NO reduction by C{sub 2}H{sub 4} in presence of O{sub 2}. In this novel reactor, thin (=20-40nm) porous catalyst films made of two different materials are sputter-deposited on opposing surfaces of thin (0.25mm) parallel solid electrolyte plates supported in the grooves of a ceramic monolithic holder and serve as sensor or electropromoted catalyst elements. Using Rh/YSZ/Pt-type catalyst elements, the 22-plate reactor operated with apparent Faradaic efficiency exceeding 25 achieving near complete fuel and NO conversion at 300C in presence of up to 1.1% O{sub 2} in the feed at gas flow rates exceeding 1.3l/min. The metal catalyst dispersion was of the order of at least 15%. The novel reactor design requires only two external electrical connections and permits easy practical utilization of the electrochemical promotion of catalysis.

  7. Synergetic mechanism of methanol–steam reforming reaction in a catalytic reactor with electric discharges

    International Nuclear Information System (INIS)

    Highlights: • Methanol–steam reforming was performed on Cu catalysts under an electric discharge. • Discharge had a synergetic effect on the catalytic reaction for methanol conversion. • Discharge lowered the temperature for catalyst activation or light off. • Discharge controlled the yield and selectivity of species in a reforming process. • Adsorption triggered by a discharge was a possible mechanism for a synergetic effect. - Abstract: Methanol–steam reforming was performed on Cu/ZnO/Al2O3 catalysts under an electric discharge. The discharge occurred between the electrodes where the catalysts were packed. The electric discharge was characterized by the discharge voltage and electric power to generate the discharge. The existence of a discharge had a synergetic effect on the catalytic reaction for methanol conversion. The electric discharge provided modified reaction paths resulting in a lower temperature for catalyst activation or light off. The discharge partially controlled the yield and selectivity of species in a reforming process. The aspect of control was examined in view of the reaction kinetics. The possible mechanisms for the synergetic effect between the catalytic reaction and electric discharge on methanol–steam reforming were addressed. A discrete reaction path, particularly adsorption triggered by an electric discharge, was suggested to be the most likely mechanism for the synergetic effect. These results are expected to provide a guide for understanding the plasma–catalyst hybrid reaction

  8. Catalytic effect of copper on the hexacyanoferrate(III)-cyanide redox reaction-II catalytic determination of copper.

    Science.gov (United States)

    López-Cueto, G; Casado-Riobó, J A

    1979-02-01

    A catalytic method for the determination of copper, based on the catalysis of the hexacyano-ferrate(III)-cyanide redox reaction, is proposed. Experimental conditions to achieve the lowest detection limit are selected from the kinetics of both the catalysed and the uncatalysed reactions. The experimental measurements can be made at room temperature without close control. The rate-constant method is the most sensitive and precise, whereas the fixed-concentration and fixed-time methods appear to be the most rapid for routine analysis. A detection limit of 1.3 ng/ml and a coefficient of variation of about 3% for the determination of 63 ng/ml can be achieved. The catalytic effect of copper seems to be highly specific. Lead(II), bismuth (III), antimony (III), iron (II), iron(III), chromium(III), lanthanum(III), cerium(III), titanium(IV), zirconium(IV) and uranium(VI) interfere by precipitation. Species such as tin(II), cobalt(II), manganese(II), sulphite and thiosulphite cause serious interference because they react with hexacyanoferrate(III). Chromate interferes by its colour. Suitable methods to avoid the interferences from antimony(III), iron(III), chromium(III), titanium(IV), zirconium(IV), uranium(VI) and chromate are proposed. PMID:18962400

  9. Investigation of catalytic reactions in novel ionic liquids

    OpenAIRE

    Dai, Jifeng

    2003-01-01

    Solvents play a very important role in organic chemistry. Most reactions must be carried out in solvents, thus for chemists, they have to deal with huge volumes of solvents everyday. Solvents can be highly damaging chemicals for two simple reasons: (1 ) they are used on a large scale, (2 ) they are often volatile which makes them difficult to contain. For the reason of environmental protection and reduction of damage to human being, clean technologies have become a major concern throughout bo...

  10. Long-time experience in catalytic flue gas cleaning and catalytic NO{sub x} reduction in biofueled boilers

    Energy Technology Data Exchange (ETDEWEB)

    Ahonen, M. [Tampella Power Inc., Tampere (Finland)

    1996-12-31

    NO emissions are reduced by primary or secondary methods. Primary methods are based on NO reduction in the combustion zone and secondary methods on flue gas cleaning. The most effective NO reduction method is selective catalytic reduction (SCR). It is based on NO reduction by ammonia on the surface of a catalyst. Reaction products are water and nitrogen. A titanium-dioxide-based catalyst is very durable and selective in coal-fired power plants. It is not poisoned by sulphur dioxide and side reactions with ammonia and sulphur dioxide hardly occur. The long time experience and suitability of a titanium-dioxide-based catalyst for NO reduction in biofuel-fired power plants was studied. The biofuels were: peat, wood and bark. It was noticed that deactivation varied very much due to the type of fuel and content of alkalinities in fuel ash. The deactivation in peat firing was moderate, close to the deactivation noticed in coal firing. Wood firing generally had a greater deactivation effect than peat firing. Fuel and fly ash were analyzed to get more information on the flue gas properties. The accumulation of alkali and alkaline earth metals and sulphates was examined together with changes in the physical composition of the catalysts. In the cases where the deactivation was the greatest, the amount of alkali and alkaline earth metals in fuels and fly ashes and their accumulation were very significant. (author) (3 refs.)

  11. Investigation of the red mud catalytic activity in carbon monoxide reaction decomposition

    OpenAIRE

    Кириченко, Алексей Геннадьевич; Колесник, Дмитрий Николаевич

    2011-01-01

    The process of iron carburization using СО-contaning gas as a catalyst red mud is investigated. Determined the catalytic activity of red mud in the decomposition reaction of CO. The effect of red mud addition to iron ore materials to improve their recoverability and carburization

  12. Catalytic Hydrotreatment of Fast Pyrolysis Oil : Model Studies on Reaction Pathways for the Carbohydrate Fraction

    NARCIS (Netherlands)

    Wildschut, J.; Arentz, J.; Rasrendra, C. B.; Venderbosch, R. H.; Heeres, H. J.

    2009-01-01

    Fast pyrolysis oil can be upgraded by a catalytic hydrotreatment (250-400 degrees C, 100-200 bar) using heterogeneous catalysts such as Ru/C to hydrocarbon-like products that can serve as liquid transportation fuels. Insight into the complex reaction pathways of the various component fractions durin

  13. In-situ scanning transmission X-ray microscopy of catalytic materials under reaction conditions

    NARCIS (Netherlands)

    de Smit, E.; Creemer, J.F.; Zandbergen, H.W.; Weckhuysen, B.M.; de Groot, F.M.F.

    2009-01-01

    In-situ Scanning X-ray Transmission Microscopy (STXM) allows the measurement of the soft X-ray absorption spectra with 10 to 30 nm spatial resolution under realistic reaction conditions. We show that STXM-XAS in combination with a micromachined nanoreactor can image a catalytic system under relevant

  14. Catalytic reaction of cytokinin dehydrogenase : preference for quinones as electron acceptors

    NARCIS (Netherlands)

    Frébortová, Jitka; Fraaije, Marco W.; Galuszka, Petr; Šebela, Marek; Peč, Pavel; Hrbáč, Jan; Novák, Ondřej; Bilyeu, Kristin D.; English, James T.; Frébort, Ivo; Sebela, M.; Pec, P.; Hrbac, J.; Frebort, [No Value

    2004-01-01

    The catalytic reaction of cytokinin oxidase/dehydrogenase (EC 1.5.99.12) was studied in detail using the recombinant flavoenzyme from maize. Determination of the redox potential of the covalently linked flavin cofactor revealed a relatively high potential dictating the type of electron acceptor that

  15. Session 6: Catalytic Dechlorination Reaction of Chlorinated Hydrocarbons with Water Using nano-structured Alumina

    Energy Technology Data Exchange (ETDEWEB)

    Abbas, Khaleel [United Arab Emirates Univ., Dept. of Chemistry, Al-Ain (United States)

    2004-07-01

    Herein, we report our recent results from a study on the catalytic dechlorination reactions of 1,2-dichloroethane (DCE) and carbon tetrachloride (CTC) with water using HSA-Al{sub 2}O{sub 3} as the catalyst. The obtained experimental results are explained. (O.M.)

  16. Study of catalytic effect of ammonium molybdate on the bisphthalonitrile resins curing reaction with aromatic amine

    Institute of Scientific and Technical Information of China (English)

    Wen Ting Li; Fang Zuo; Kun Jia; Xiao Bo Liu

    2009-01-01

    A kind of catalyst, ammonium molybdate was developed in this paper to promote the curing reaction of bisphthalonitrile resins with aromatic amine as curing agent, and the catalytic effect was studied by differential scanning calorimetry (DSC), rheometric measurements and thermogravimetric analysis (TGA). The results indicated that the catalyst could improve the curing rate and increase the curing degree, which could be regulated by the content of the catalyst used in the reaction.

  17. Oscillatory three-phase flow reactor for studies of bi-phasic catalytic reactions.

    Science.gov (United States)

    Abolhasani, Milad; Bruno, Nicholas C; Jensen, Klavs F

    2015-05-28

    A multi-phase flow strategy, based on oscillatory motion of a bi-phasic slug within a fluorinated ethylene propylene (FEP) tubular reactor, under inert atmosphere, is designed and developed to address mixing and mass transfer limitations associated with continuous slug flow chemistry platforms for studies of bi-phasic catalytic reactions. The technique is exemplified with C-C and C-N Pd catalyzed coupling reactions. PMID:25876959

  18. In-situ scanning transmission X-ray microscopy of catalytic materials under reaction conditions

    OpenAIRE

    Smit, E.; Creemer, J.F.; H.W. Zandbergen; Weckhuysen, B. M.; Groot, F.M.F. de

    2009-01-01

    In-situ Scanning X-ray Transmission Microscopy (STXM) allows the measurement of the soft X-ray absorption spectra with 10 to 30 nm spatial resolution under realistic reaction conditions. We show that STXM-XAS in combination with a micromachined nanoreactor can image a catalytic system under relevant reaction conditions, and provide detailed information on the morphology and composition of the catalyst material. The nanometer resolution combined with powerful chemical speciation by XAS and the...

  19. The Self-catalytic Esterification Reaction of O-Phosphoryl Serine Derivative

    Institute of Scientific and Technical Information of China (English)

    Jin Tang DU; Yan Mei LI; Zhong Zhou CHEN; Shi Zhong LUO; Yu Fen ZHAO

    2005-01-01

    O-Phosphoryl serine derivative can perform self-catalytic esterification reaction in the mixture of CH3OH and CHCl3 at the room temperature. The phosphoryl group participation was the key step of the esterification. This type of reactions were proposed through an intermediate of mixed phosphoric-carboxylic anhydride that might provide a clue to the function of the phosphoryl group in the phosphorylated enzymes and in the prebiotic synthesis of protein.

  20. Oscillatory three-phase flow reactor for studies of bi-phasic catalytic reactions

    OpenAIRE

    Abolhasani, Milad; Bruno, Nicholas C.; Jensen, Klavs F.

    2015-01-01

    A multi-phase flow strategy, based on oscillatory motion of a bi-phasic slug within a fluorinated ethylene propylene (FEP) tubular reactor, under inert atmosphere, is designed and developed to address mixing and mass transfer limitations associated with continuous slug flow chemistry platforms for studies of bi-phasic catalytic reactions. The technique is exemplified with C–C and C–N Pd catalyzed coupling reactions.

  1. Catalytic and Gas-Solid Reactions Involving HCN over Limestone

    DEFF Research Database (Denmark)

    Jensen, Anker; Johnsson, Jan Erik; Dam-Johansen, Kim

    1997-01-01

    In coal-fired combustion systems solid calcium species may be present as ash components or limestone added to the combustion chamber. In this study heterogeneous reactions involving HCN over seven different limestones were investigated in a laboratory fixed-bed quartz reactor at 873-1,173 K....... Calcined limestone is an effective catalyst for oxidation of HCN. Under conditions with complete conversion of HCN at O-2 concentrations above about 5,000 ppmv the selectivity for formation of NO and N2O is 50-70% and below 5%, respectively. Nitric oxide can be reduced by HCN to N-2 in the absence of O-2...

  2. Interactions Between Surface Reactions and Gas-phase Reactions in Catalytic Combustion and Their Influence on Ignition of HCCI Engine

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    The catalytic combustion of methane in a microchannel whose surface was coated with platinum(Pt)catalyst was studied by numerical-simulation. The effects of gas-phase reactions on the whole catalytic combustion process were analyzed at a high inlet pressure. A sensitivity analysis of the detailed mechanisms of the surface reaction of methane on Pt revealed that the most sensitive reactions affecting the heterogeneous ignition are oxygen adsorption/desorption and methane adsorption, and the most sensitive reactions affecting the homogeneous ignition are OH and H2O adsorption/desorption. The combustion process of the homogeneous charge compression ignition(HCCI) engine whose piston face was coated with Pt catalyst was simulated. The effects of catalysis and the most sensitive reactions on the ignition timing and the concentration of the main intermediate species during the HCCI engine combustion are discussed. The results show that the ignition timing of the HCCI engine can be increased by catalysis, and the most sensitive reactions affecting the ignition timing of the HCCI engine are OH and H2O adsorption/desorption.

  3. Catalytic Activity of Iridium Dioxide With Different Morphologies for Oxygen Reduction Reaction

    Institute of Scientific and Technical Information of China (English)

    WANG Guangjin; HUANG Fei; XU Tian; YU Yi; CHENG Feng; ZHANG Yue; PAN Mu

    2015-01-01

    Iridium dioxide with different morphologies (nanorod and nanogranular) is successfully prepared by a modiifed sol-gel and Adams methods. The catalytic activity of both samples for oxygen reduction reaction is investigated in an alkaline solution. The electrochemical results show that the catalytic activity of the nanogranular IrO2 sample is superior to that of the nanorod sample due to its higher onset potential for oxygen reduction reaction and higher electrode current density in low potential region. The results of Koutecky-Levich analysis indicate that the oxygen reduction reaction catalyzed by both samples is a mixture transfer pathway. It is dominated by four electron transfer pathway for both samples in high overpotential area, while it is controlled by two electron transfer process for both samples in low overpotential area.

  4. An Experiment on Mining Chemical Reaction Databases

    OpenAIRE

    Berasaluce, Sandra; Laurenço, Claude; Napoli, Amedeo; Niel, Gilles

    2004-01-01

    In this paper, we present an experiment on knowledge discovery in chemical reaction databases. Chemical reactions are the main elements on which relies synthesis in organic chemistry, and this is why chemical reactions databases are of first importance. From a problem-solving process perspective, synthesis in organic chemistry must be considered at several levels of abstraction: mainly a strategic level where general synthesis methods are involved, and a tactic level where actual chemical rea...

  5. Polyethersulfone hollow fiber modified with poly(styrenesulfonate) and Pd nanoparticles for catalytic reaction

    Science.gov (United States)

    Emin, C.; Gu, Y.; Remigy, J.-C.; Lahitte, J.-F.

    2015-07-01

    The aim of this work is the synthesis of polymer-stabilized Pd nanoparticles (PdNP) inside a functionalized polymeric porous membrane in order to develop hybrid catalytic membrane reactors and to test them in model metal-catalyzed organic reactions. For this goal, a polymeric membrane support (Polyethersulfone hollow fiber-shaped) was firstly functionalized with an ionogenic polymer (i.e. poly(styrenesulfonate) capable to retain PdNP precursors using an UV photo-grafting method. PdNP were then generated inside the polymeric matrix by chemical reduction of precursor salts (intermatrix synthesis). The catalytic performance of the PdNP catalytic membranes was evaluated using reduction of nitrophenol by sodium borohydride (NaBH4) in water.

  6. Graphene-Semiconductor Catalytic Nanodiodes for Quantitative Detection of Hot Electrons Induced by a Chemical Reaction.

    Science.gov (United States)

    Lee, Hyosun; Nedrygailov, Ievgen I; Lee, Young Keun; Lee, Changhwan; Choi, Hongkyw; Choi, Jin Sik; Choi, Choon-Gi; Park, Jeong Young

    2016-03-01

    Direct detection of hot electrons generated by exothermic surface reactions on nanocatalysts is an effective strategy to obtain insight into electronic excitation during chemical reactions. For this purpose, we fabricated a novel catalytic nanodiode based on a Schottky junction between a single layer of graphene and an n-type TiO2 layer that enables the detection of hot electron flows produced by hydrogen oxidation on Pt nanoparticles. By making a comparative analysis of data obtained from measuring the hot electron current (chemicurrent) and turnover frequency, we demonstrate that graphene's unique electronic structure and extraordinary material properties, including its atomically thin nature and ballistic electron transport, allow improved conductivity at the interface between the catalytic Pt nanoparticles and the support. Thereby, graphene-based nanodiodes offer an effective and facile way to approach the study of chemical energy conversion mechanisms in composite catalysts with carbon-based supports. PMID:26910271

  7. Modeling the Catalysis of Anti-Cocaine Catalytic Antibody: Competing Reaction Pathways and Free Energy Barriers

    OpenAIRE

    Pan, Yongmei; Gao, Daquan; Zhan, Chang-Guo

    2008-01-01

    The competing reaction pathways and the corresponding free energy barriers for cocaine hydrolysis catalyzed by an anti-cocaine catalytic antibody, mAb 15A10, were studied by using a novel computational strategy based on the binding free energy calculations on the antibody binding with cocaine and transition states. The calculated binding free energies were used to evaluate the free energy barrier shift from the cocaine hydrolysis in water to the antibody-catalyzed cocaine hydrolysis for each ...

  8. Electro-catalytic activity of Ni–Co-based catalysts for oxygen evolution reaction

    Energy Technology Data Exchange (ETDEWEB)

    Ju, Hua [School of Urban Rail Transportation, Soochow University, Suzhou 215006 (China); Li, Zhihu [College of Physics, Optoelectronics and Energy, Soochow University, Moye Rd. 688, Suzhou 215006 (China); Xu, Yanhui, E-mail: xuyanhui@suda.edu.cn [College of Physics, Optoelectronics and Energy, Soochow University, Moye Rd. 688, Suzhou 215006 (China)

    2015-04-15

    Graphical abstract: The electro-catalytic activity of different electro-catalysts with a porous electrode structure was compared considering the real electrode area that was evaluated by cyclic measurement. - Highlights: • Ni–Co-based electro-catalysts for OER have been studied and compared. • The real electrode area is calculated and used for assessing the electro-catalysts. • Exchange current and reaction rate constant are estimated. • Ni is more useful for OER reaction than Co. - Abstract: In the present work, Ni–Co-based electrocatalysts (Ni/Co = 0:6, 1:5, 2:4, 3:3, 4:2, 5:1 and 6:0) have been studied for oxygen evolution reaction. The phase structure has been analyzed by X-ray diffraction technique. Based on the XRD and SEM results, it is believed that the synthesized products are poorly crystallized. To exclude the disturbance of electrode preparation technology on the evaluation of electro-catalytic activity, the real electrode surface area is calculated based on the cyclic voltammetry data, assumed that the specific surface capacitance is 60 μF cm{sup −2} for metal oxide electrode. The real electrode area data are used to calculate the current density. The reaction rate constant of OER at different electrodes is also estimated based on basic reaction kinetic equations. It is found that the exchange current is 0.05–0.47 mA cm{sup −2} (the real surface area), and the reaction rate constant has an order of magnitude of 10{sup −7}–10{sup −6} cm s{sup −1}. The influence of the electrode potential on OER rate has been also studied by electrochemical impedance spectroscopy (EIS) technique. Our investigation has shown that the nickel element has more contribution than the cobalt; the nickel oxide has the best electro-catalytic activity toward OER.

  9. Electro-catalytic activity of Ni–Co-based catalysts for oxygen evolution reaction

    International Nuclear Information System (INIS)

    Graphical abstract: The electro-catalytic activity of different electro-catalysts with a porous electrode structure was compared considering the real electrode area that was evaluated by cyclic measurement. - Highlights: • Ni–Co-based electro-catalysts for OER have been studied and compared. • The real electrode area is calculated and used for assessing the electro-catalysts. • Exchange current and reaction rate constant are estimated. • Ni is more useful for OER reaction than Co. - Abstract: In the present work, Ni–Co-based electrocatalysts (Ni/Co = 0:6, 1:5, 2:4, 3:3, 4:2, 5:1 and 6:0) have been studied for oxygen evolution reaction. The phase structure has been analyzed by X-ray diffraction technique. Based on the XRD and SEM results, it is believed that the synthesized products are poorly crystallized. To exclude the disturbance of electrode preparation technology on the evaluation of electro-catalytic activity, the real electrode surface area is calculated based on the cyclic voltammetry data, assumed that the specific surface capacitance is 60 μF cm−2 for metal oxide electrode. The real electrode area data are used to calculate the current density. The reaction rate constant of OER at different electrodes is also estimated based on basic reaction kinetic equations. It is found that the exchange current is 0.05–0.47 mA cm−2 (the real surface area), and the reaction rate constant has an order of magnitude of 10−7–10−6 cm s−1. The influence of the electrode potential on OER rate has been also studied by electrochemical impedance spectroscopy (EIS) technique. Our investigation has shown that the nickel element has more contribution than the cobalt; the nickel oxide has the best electro-catalytic activity toward OER

  10. Continuous-flow stereoselective organocatalyzed Diels-Alder reactions in a chiral catalytic "homemade" HPLC column.

    Science.gov (United States)

    Chiroli, Valerio; Benaglia, Maurizio; Cozzi, Franco; Puglisi, Alessandra; Annunziata, Rita; Celentano, Giuseppe

    2013-07-19

    Continuous-flow organocatalyzed Diels-Alder reactions have been performed with excellent enantioselectivity for the first time in a chiral "homemade" HPLC column, packed with silica on which a MacMillan catalyst has been supported by a straightforward immobilization procedure. The versatility of the system was also proven by running with the same column continuous-flow stereoselective reactions with three different substrates, showing that the catalytic reactor may efficiently work in continuo for more than 150 h; the regeneration of the HPLC column was also demonstrated, allowing to further extend the activity of the reactor to more than 300 operating hours. PMID:23808663

  11. Effect of reaction time on the characteristics of catalytically grown boron nitride nanotubes

    International Nuclear Information System (INIS)

    The paper reports on the growth of boron nitride nanotube (BNNTs) on Si substrate by catalytic chemical vapor deposition technique and the effect of reaction time and temperature on the size and purity were investigated. Scanning electron microscopy image revealed the bamboo-like BNNTs of multiwalled type with interlayer spacing of 0.34 nm. EDX analysis described the presence of a small percentage of Mg in the sample, indicating the combination of base-tip growth model for the sample synthesized at 1200°C. The reaction time has an effect of extending the length of the BNNTs until the catalyst is oxidized or covered by growth precursor

  12. Electrochemical promotion of catalytic reactions with Pt/C (or Pt/Ru/C)//PBI catalysts

    DEFF Research Database (Denmark)

    Petrushina, Irina; Bjerrum, Niels; Bandur, Viktor;

    2007-01-01

    The paper is an overview of the results of the investigation on electrochemical promotion of three catalytic reactions: methane oxidation with oxygen, NO reduction with hydrogen at 135 degrees C and Fischer-Tropsch synthesis (FTS) at 170 degrees C in the [CH4/O-2(or NO/H-2 or CO/H-2)/Ar//Pt(or Pt...... reactions have been promoted by the electrochemically produced hydrogen. It has been found that the NO reduction with hydrogen on the Pt/PBI strongly depends on NO and hydrogen partial pressures in the working gas mixture. At higher NO and H-2 partial pressures the catalysis is promoted by the...

  13. Effect of reaction time on the characteristics of catalytically grown boron nitride nanotubes

    Energy Technology Data Exchange (ETDEWEB)

    Mohamed, Norani Muti, E-mail: noranimuti-mohamed@petronas.com.my, E-mail: pervaiz-pas@yahoo.com, E-mail: shuaib-penang@yahoo.com, E-mail: zainabh@petronas.com.my; Ahmad, Pervaiz, E-mail: noranimuti-mohamed@petronas.com.my, E-mail: pervaiz-pas@yahoo.com, E-mail: shuaib-penang@yahoo.com, E-mail: zainabh@petronas.com.my; Saheed, Mohamed Shuaib Mohamed, E-mail: noranimuti-mohamed@petronas.com.my, E-mail: pervaiz-pas@yahoo.com, E-mail: shuaib-penang@yahoo.com, E-mail: zainabh@petronas.com.my; Burhanudin, Zainal Arif, E-mail: noranimuti-mohamed@petronas.com.my, E-mail: pervaiz-pas@yahoo.com, E-mail: shuaib-penang@yahoo.com, E-mail: zainabh@petronas.com.my [Center of Innovative Nanostructures and Nanodevices (COINN), Universiti Teknologi PETRONAS, Bandar Seri Iskandar, 31750, Tronoh, Perak (Malaysia)

    2014-10-24

    The paper reports on the growth of boron nitride nanotube (BNNTs) on Si substrate by catalytic chemical vapor deposition technique and the effect of reaction time and temperature on the size and purity were investigated. Scanning electron microscopy image revealed the bamboo-like BNNTs of multiwalled type with interlayer spacing of 0.34 nm. EDX analysis described the presence of a small percentage of Mg in the sample, indicating the combination of base-tip growth model for the sample synthesized at 1200°C. The reaction time has an effect of extending the length of the BNNTs until the catalyst is oxidized or covered by growth precursor.

  14. Single-Site Palladium(II) Catalyst for Oxidative Heck Reaction: Catalytic Performance and Kinetic Investigations

    Energy Technology Data Exchange (ETDEWEB)

    Duan, Hui; Li, Mengyang; Zhang, Guanghui; Gallagher, James R.; Huang, Zhiliang; Sun, Yu; Luo, Zhong; Chen, Hongzhong; Miller, Jeffrey T.; Zou, Ruqiang; Lei, Aiwen; Zhao, Yanli

    2015-01-01

    ABSTRACT: The development of organometallic single-site catalysts (SSCs) has inspired the designs of new heterogeneous catalysts with high efficiency. Nevertheless, the application of SSCs in certain modern organic reactions, such as C-C bond formation reactions, has still been less investigated. In this study, a single-site Pd(II) catalyst was developed, where 2,2'-bipyridine-grafted periodic mesoporous organosilica (PMO) was employed as the support of a Pd(II) complex. The overall performance of the single-site Pd(II) catalyst in the oxidative Heck reaction was then investigated. The investigation results show that the catalyst displays over 99% selectivity for the product formation with high reaction yield. Kinetic profiles further confirm its high catalytic efficiency, showing that the rate constant is nearly 40 times higher than that for the free Pd(II) salt. X-ray absorption spectroscopy reveals that the catalyst has remarkable lifetime and recyclability.

  15. Automated Prediction of Catalytic Mechanism and Rate Law Using Graph-Based Reaction Path Sampling.

    Science.gov (United States)

    Habershon, Scott

    2016-04-12

    In a recent article [ J. Chem. Phys. 2015 , 143 , 094106 ], we introduced a novel graph-based sampling scheme which can be used to generate chemical reaction paths in many-atom systems in an efficient and highly automated manner. The main goal of this work is to demonstrate how this approach, when combined with direct kinetic modeling, can be used to determine the mechanism and phenomenological rate law of a complex catalytic cycle, namely cobalt-catalyzed hydroformylation of ethene. Our graph-based sampling scheme generates 31 unique chemical products and 32 unique chemical reaction pathways; these sampled structures and reaction paths enable automated construction of a kinetic network model of the catalytic system when combined with density functional theory (DFT) calculations of free energies and resultant transition-state theory rate constants. Direct simulations of this kinetic network across a range of initial reactant concentrations enables determination of both the reaction mechanism and the associated rate law in an automated fashion, without the need for either presupposing a mechanism or making steady-state approximations in kinetic analysis. Most importantly, we find that the reaction mechanism which emerges from these simulations is exactly that originally proposed by Heck and Breslow; furthermore, the simulated rate law is also consistent with previous experimental and computational studies, exhibiting a complex dependence on carbon monoxide pressure. While the inherent errors of using DFT simulations to model chemical reactivity limit the quantitative accuracy of our calculated rates, this work confirms that our automated simulation strategy enables direct analysis of catalytic mechanisms from first principles. PMID:26938837

  16. Monodisperse metal nanoparticle catalysts on silica mesoporous supports: synthesis, characterizations, and catalytic reactions

    Energy Technology Data Exchange (ETDEWEB)

    Somorjai, G.A.

    2009-09-14

    The design of high performance catalyst achieving near 100% product selectivity at maximum activity is one of the most important goals in the modern catalytic science research. To this end, the preparation of model catalysts whose catalytic performances can be predicted in a systematic and rational manner is of significant importance, which thereby allows understanding of the molecular ingredients affecting the catalytic performances. We have designed novel 3-dimensional (3D) high surface area model catalysts by the integration of colloidal metal nanoparticles and mesoporous silica supports. Monodisperse colloidal metal NPs with controllable size and shape were synthesized using dendrimers, polymers, or surfactants as the surface stabilizers. The size of Pt, and Rh nanoparticles can be varied from sub 1 nm to 15 nm, while the shape of Pt can be controlled to cube, cuboctahedron, and octahedron. The 3D model catalysts were generated by the incorporation of metal nanoparticles into the pores of mesoporous silica supports via two methods: capillary inclusion (CI) and nanoparticle encapsulation (NE). The former method relies on the sonication-induced inclusion of metal nanoparticles into the pores of mesoporous silica, whereas the latter is performed by the encapsulation of metal nanoparticles during the hydrothermal synthesis of mesoporous silica. The 3D model catalysts were comprehensively characterized by a variety of physical and chemical methods. These catalysts were found to show structure sensitivity in hydrocarbon conversion reactions. The Pt NPs supported on mesoporous SBA-15 silica (Pt/SBA-15) displayed significant particle size sensitivity in ethane hydrogenolysis over the size range of 1-7 nm. The Pt/SBA-15 catalysts also exhibited particle size dependent product selectivity in cyclohexene hydrogenation, crotonaldehyde hydrogenation, and pyrrole hydrogenation. The Rh loaded SBA-15 silica catalyst showed structure sensitivity in CO oxidation reaction. In

  17. Catalytic activity of pyrite for coal liquefaction reaction; Tennen pyrite no shokubai seino ni kansuru kento

    Energy Technology Data Exchange (ETDEWEB)

    Hirano, K.; Kozu, M.; Okada, T.; Kobayashi, M. [Nippon Coal Oil Co. Ltd., Tokyo (Japan)

    1996-10-28

    Since natural pyrite is easy to obtain and cheap as coal liquefaction catalyst, it is to be used for the 150 t/d scale NEDOL process bituminous coal liquefaction pilot plant. NEDO and NCOL have investigated the improvement of catalytic activity of pulverized natural pyrite for enhancing performance and economy of the NEDOL process. In this study, coal liquefaction tests were conducted using natural pyrite catalyst pulverized by dry-type bowl mill under nitrogen atmosphere. Mechanism of catalytic reaction of the natural pyrite was discussed from relations between properties of the catalyst and liquefaction product. The natural pyrite provided an activity to transfer gaseous hydrogen into the liquefaction product. It was considered that pulverized pyrite promotes the hydrogenation reaction of asphaltene because pulverization increases its contact rate with reactant and the amount of active points on its surface. It was inferred that catalytic activity of pyrite is affected greatly by the chemical state of Fe and S on its surface. 3 refs., 4 figs., 1 tab.

  18. Characterization of catalytic supports based in mixed oxides for control reactions of NO and N2O

    International Nuclear Information System (INIS)

    The catalytic supports Al2O3, La2O3 and Al2O3-La2O3 were prepared by the Precipitation and Coprecipitation techniques. The catalytic supports Al2O3, La2O3 and Al2O3-La2O3 were characterized by several techniques to determine: texture (Bet), crystallinity (XRD), chemical composition (Sem)(Ftir) and it was evaluated their total acidity by reaction with 2-propanol. The investigation will be continued with the cobalt addition and this will be evaluated for its catalytic activity in control reactions of N O and N2O. (Author)

  19. Plasma-catalytic hybrid system using spouted bed with a gliding arc discharge: CH4 reforming as a model reaction

    Science.gov (United States)

    Lee, H.; Sekiguchi, H.

    2011-07-01

    A combination of a gliding arc discharge and a spouted catalytic bed was used to investigate a plasma-catalytic hybrid system using CH4 reforming as a model reaction. Alumina-supported catalysts that contained 0.5 wt% of Pt, Pd, Rh, and Ru (denoted as Pt/Al2O3, Pd/Al2O3, Rh/Al2O3 and Ru/Al2O3, respectively) were used. For comparison, active Al2O3 particles were also examined. The conversion of CH4 and the selectivity of the product were investigated by changing the feed flow rate and reaction time. The production of C2H2, H2 and soot was observed in the gliding arc discharge without a catalyst. Using Pt/Al2O3 and Pd/Al2O3with the gliding arc discharge, C2H4, C2H6 and C2H2 were produced. It is considered that C2H4 and C2H6 were formed by the hydrogenation of C2H2 on the active site of Pt/Al2O3 and Pd/Al2O3. A stronger resistance to deactivation was shown in the presence of Pd/Al2O3 than in the presence of Pt/Al2O3, whereas the selectivity of hydrocarbon using Rh/Al2O3 and Ru/Al2O3 showed a tendency similar to that in active Al2O3 and non-catalytic experiments. The proposed reactor has a potential to improve the selectivity of the plasma process.

  20. Reactions of hypochlorous acid with biological substrates are activated catalytically by tertiary amines.

    Science.gov (United States)

    Prütz, W A

    1998-09-15

    The activation of reactions of HOCl with a variety of model substrates by tertiary amines was investigated spectroscopically by tandem-mix and stopped-flow techniques. HOCl-induced chlorination of salicylate can be sped up by several orders of magnitude by catalytic amounts of trimethylamine (TMN). The effect is obviously due to the fast generation of reactive quarternary chloramonium ions, TMN+ Cl, which act as chain carrier in a catalytic reaction cycle. Of various catalysts tested, quinine shows the highest activity; this is attributable to the quinuclidine (QN) substituent, a bicyclic tertiary amine, forming a particularly reactive chloro derivative, QN+ Cl, which does not decompose autocatalytically. The rate of catalytic salicylate chlorination as a function of pH (around pH 7) depends not at least on the basicity of the tertiary amine; the rate increases with pH in the cases of TMN and quinuclidine (high basicity), but decreases with pH in the case of MES (low basicity). Tertiary amines also catalyze the interaction between HOCl and alkenes, as shown using sorbate as model. Reaction of HOCl with the nucleotides GMP and CMP is sped up remarkably by catalytic amounts of tertiary amines. In the case of GMP the same product spectrum is produced by HOCl in absence and presence of catalyst, but a change in the product spectra is obtained when AMP and CMP are reacted with HOCl in presence of catalyst. Using poly(dA-dT).poly(dA-dT) as DNA model, it is shown that HOCl primarily induces an absorbance increase at 263 nm, which indicates unfolding of the double strand due to fast chlorination of thymidine; a subsequent secondary absorbance decrease can be explained by slow chlorination of adenosine. Both the primary and secondary processes are activated by catalytic amounts of quinine. No evidence was found for a radical pathway in TMN-mediated oxidation of formate by HOCl. The present results suggest that low concentrations of certain tertiary amines have the potential

  1. Catalytic hydrocarbon reactions over supported metal oxides. Progress report, April 1, 1994--January 31, 1995

    Energy Technology Data Exchange (ETDEWEB)

    Ekerdt, J.G.

    1995-01-31

    Oxide catalysis plays a central role in hydrocarbon processing and improvements in catalytic activity or selectivity are of great technological importance because these improvements will translate directly into more efficient utilization of hydrocarbon supplies and lower energy consumption in separation processes. An understanding of the relationships between surface structure and catalytic properties is needed to describe and improve oxide catalysts. Our approach has been to prepare supported oxides that have a specific structure and oxidation state and then employ these structures in reaction studies. Our current research program is focused on studying the fundamental relationships between structure and reactivity for two important reactions that are present in many oxide-catalyzed processes, partial oxidation and carbon-carbon bond formation. Oxide catalysis can be a complex process with both metal cation and oxygen anions participating in the chemical reactions. From an energy perspective carbon-carbon bond formation is particularly relevant to CO hydrogenation in isosynthesis. Hydrogenolysis and hydrogenation form the basis for heteroatom removal in fuels processing. Understanding the catalysis of these processes (and others) requires isolating reaction steps in the overall cycle and determining how structure and composition influence the individual reaction steps. Specially designed oxides, such as we use, permit one to study some of the steps in oxidation, carbon-carbon coupling and heteroatom removal catalysis. During the course of our studies we have: (1) developed methods to form and stabilize various Mo and W oxide structures on silica; (2) studied C-H abstraction reactions over the fully oxidized cations; (3) studied C-C bond coupling by methathesis and reductive coupling of aldehydes and ketones over reduced cation structures; and (4) initiated a study of hydrogenation and hydrogenolysis over reduced cation structures.

  2. Deuterium–tritium catalytic reaction in fast ignition: Optimum parameters approach

    Indian Academy of Sciences (India)

    B Khanbabaei; A Ghasemizad; S Khoshbinfar

    2014-09-01

    One of the main concerns about the currentworking on nuclear power reactors is the potential hazard of their radioactive waste. There is hope that this issue will be reduced in next generation nuclear fusion power reactors. Reactors will release nuclear energy through microexplosions that occur in a mixture of hydrogen isotopes of deuterium and tritium. However, there exist radiological hazards due to the accumulation of tritium in the blanket layer. A catalytic fusion reaction of DT mixture may stand between DD and an equimolar DT approach in which the fusion process continues with a small amount of tritium seed. In this paper, we investigate the possibility of DT reaction in the fast ignition (FI) scheme. The kinematic study of the main mechanism of the energy gain–loss term, which may disturb the ignition and burn process, was performed in FI and the optimum values of precompressed fuel and proton beam driver were derived. The recommended values of fuel parameters are: areal density $ρ R ≥ 5\\cdot$cm-2 and initial tritium fraction ≤ 0.025. For the proton beam, the corresponding optimum interval values are proton average energy $3≤ E_p ≤ 10$ MeV, pulse duration $5 ≤ t_p ≤ 15$ ps and power $5≤ W_p ≤ 12 × 10^{22}$ (keV$\\cdot$cm3$\\cdot$ps-1). It was proved that under the above conditions, a fast ignition DT reaction stays in the catalytic regime.

  3. Catalytic hydrocarbon reactions over supported metal oxides. Final report, August 1, 1986--July 31, 1995

    Energy Technology Data Exchange (ETDEWEB)

    Ekerdt, J.G.

    1995-10-20

    Oxide catalysis plays a central role in hydrocarbon processing and improvements in catalytic activity or selectivity are of great technological importance because these improvements will translate directly into more efficient utilization of hydrocarbon supplies and lower energy consumption in separation processes. An understanding of the relationships between surface structure and catalytic properties is needed to describe and improve oxide catalysts. The approach has been to prepare supported oxides that have a specific structure and oxidation state and then employ these structures in reaction studies. The current research program is focused on studying the fundamental relationships between structure and reactivity for two important reactions that are present in many oxide-catalyzed processes, partial oxidation and carbon-carbon bond formation. During the course of these studies the author has: (1) developed methods to form and stabilize various Mo and W oxide structures on silica; (2) studied C-H abstraction reactions over the fully oxidized cations; (3) studied C-C bond coupling by metathesis and reductive coupling of aldehydes and ketones over reduced cation structures; and (4) initiated a study of hydrogenation and hydrogenolysis over reduced cation structures.

  4. Forced thermal cycling of catalytic reactions: experiments and modelling

    DEFF Research Database (Denmark)

    Jensen, Søren; Olsen, Jakob Lind; Thorsteinsson, Sune; Hansen, Ole; Quaade, Ulrich

    2007-01-01

    at about 1 Hz. A model for the rate enhancement that includes the surface kinetics and the dynamic partial pressure variations in the reactor is introduced. The model predicts a levelling off of the rate enhancement with frequency at about 1 Hz. The experimentally observed decrease above 1 Hz is...

  5. Final Report: Catalytic Hydrocarbon Reactions over Supported Metal Oxides, August 1, 1995 - July 31, 1999

    Energy Technology Data Exchange (ETDEWEB)

    Ekerdt, John G.

    1999-07-31

    The research program focused on the catalysis of hydrodesulfurization (HDS) over molybdenum-based catalysts and how catalyst composition, redox ability, structure and neighboring sites control the catalytic properties of metal oxides. We sought to understand the catalytic features/sites that control hydrogenation, hydrogenolysis, and isomerization during HDS. Unprompted silica-supported molybdenum oxides and molybdenum sulfides were studied. Model catalyst systems were prepared from organometallic precursors or cluster compounds to generate supported structures that feature Mo(II) and Mo(IV) cations that are isolated or in ensembles and that have either Mo-O or Mo-S bonds. Conventional MOS{sub 2} catalysts, which contain both edge and rim sites, were be studied. Finally, single-layer MOS{sub 2} structures were also prepared from 2H-MoS{sub 2} powder so that the model systems could be compared against a disulfide catalyst that only involves rim sites. Catalytic reactions for thiophene and tetrahydrothione were studied over the various catalysts. Oxidation states were determined using X-ray photoelectron spectroscopy. X-ray crystallography was used to characterize and follow changes in the MOS{sub 2} structures. The program on metal oxides prepared supported oxides that have a specific structure and oxidation state to serve as model templates for the more complex commercial catalysts and then employed these structures in reaction studies. This focus area examined the relationships between structure and cation redox characteristics in oxidation catalysis. Infrared and Raman spectroscopy were used to characterize the cations and reaction intermediates.

  6. Synthesis of Novel Chiral Dibenzo [ a, c ] cycloheptadiene Bis(oxazoline) and Catalytic Asymmetric Reactions

    Institute of Scientific and Technical Information of China (English)

    FU Bin; DU Da-Ming; WANG Jian-Bo

    2003-01-01

    @@ Over the last decade, C2-symmetric chiral oxazoline metal complexes have been recognized as an effective classof chiral catalyst in a variety of transition metal catalyzed asymmetric reactions. [1] High catalytic activities and enantiomeric excesses have been obtained using C2-symmetric chiral ligands in conjunction with suitable transition metal ion, for example, the hydrosilylation of ketone, allylic alkylation, Michael addition, Diels-Alder cycloaddition, and cyclopropanation. Thus, the design and synthesis of new chiral oxazoline ligands have inspired many scientists to work with great efforts.

  7. The selective catalytic reduction (SCR) of NO with NH3 at vanadium oxide catalysts: Adsorption, diffusion, reaction

    International Nuclear Information System (INIS)

    The selective catalytic reduction (SCR) of NOx with NH3 over vanadium based metal-oxide (VOx) catalysts has been proven to be one of the most effective NOx reduction processes. Even though it is widely used in commercial applications details of the reaction mechanism are still under debate. Experiments show that adsorption, diffusion, and reactions with NO and (de)hydrogenation processes at the VOx surface contribute elementary steps. These processes are examined in theoretical studies employing density-functional theory together with gradient corrected functionals. The VOx substrate is modeled by clusters cut out from the ideal V2O5(010) surface where peripheral oxygen bonds are saturated by hydrogen. Apart from the perfect oxide surface also differently reduced surfaces are considered by introducing oxygen vacancies. NH3 is found to interact only weakly with the perfect V2O5(010) surface. In the presence of OH groups (Broensted acid sites) NH3 can form a surface NH4+ species. NH3 can also interact with the surface near oxygen vacancies, adsorbing at vanadium centers of lower coordination (Lewis acid sites). In contrast, NO interacts much more weakly with the surface. Further, simultaneous NO, NH3 adsorption and SCR reaction scenarios at Broensted and Lewis acid sites are examined. They result in different reaction paths and intermediates as will be discussed in detail.

  8. Evidence for the powerful catalytic ability of imidozirconocene complex from its epoxide ring cleavage reactions - A DFT mechanistic view

    Indian Academy of Sciences (India)

    Dhurairajan Senthilnathan; Rajadurai Vijay Solomon; Ponnambalam Venuvanalingam

    2012-01-01

    Imidozirconocene complex is known for its bifunctional reactivity and catalytic ability and this complex mediates ring cleavage of epoxides. Cyclooctene oxide (1) Norbornene oxide (2) and 2,5-dimethyl cyclohexene oxide (3) undergo ring cleavage in the presence of imidozirconocene complex. Epoxide 1 has accessible -hydrogens (type I) while epoxide 2 and 3 do not have them (type II). Normally type I epoxides undergo elimination while type II epoxides prefer insertion. All the insertion reactions lead to five-membered metallacycle formation and elimination results in thermodynamically stable allyl-alkoxy product. The insertion is a two-step process following either diradical or zwitterionic pathway, while elimination is a one-step concerted reaction. DFT (density functional theory) modelling of these reactions at B3LYP/LANL2DZ level show that epoxide 1 undergoes elimination in agreement with experiment. However, calculations indicate that epoxide (2) proceeds through diradical intermediate in contrast to experimental observations. Surprisingly, epoxide (3) that has both the positions blocked by methyl groups undergoes elimination rather than insertion. AIM and EDA analyses offer further insights on the reaction mechanism and bifunctional reactivity of imidozirconozene complex.

  9. Neutral imidazole is the electrophile in the reaction catalyzed by triosephosphate isomerase: Structural origins and catalytic implications

    International Nuclear Information System (INIS)

    To illuminate the role of histidine-95 in the catalytic reaction mediated by triosephosphate isomerase, 13C and 15N NMR titration studies have been carried out both on the wild-type enzyme and on a mutant isomerase in which the single remaining histidine (that at the active site) has been isotopically enriched in the imidazole ring. 15N NMR has proved especially useful in the unambiguous demonstration that the imidazole ring of histidine-95 is uncharged over the entire pH range of isomerase activity, between pH 5 and pH 9.9. The results require that the positively charged imidazolium cation of histidine-95 donates a proton to the developing charge on the substrate's carbonyl oxygen. 15N NMR experiments on the enzyme in the presence of the reaction intermediate analogue phosphoglycolohydroxamate show the presence of a strong hydrogen bond between Nε2 of histidine-95 and the bound inhibitor. These findings indicate that, in the catalyzed reaction, proton abstraction from C-1 of dihydroxyacetone phosphate first yields an enediolate intermediate that is strongly hydrogen bonded to the neutral imidazole side chain of histidine-95. To the authors knowledge, this is the first reported example of the participation of an imidazolate side chain in an enzyme-catalyzed reaction

  10. Exploring the learnings derived from catalytic experiences in a leadership context

    OpenAIRE

    Daphna S. Horowitz; René van Eeden

    2015-01-01

    Orientation: Personal leadership comprises self-awareness, authenticity, inspiration and passion. The concept of personal leadership was explored together with its relationship with leadership-related learnings derived from a catalytic experience.Research purpose: The objective of the study was to explore the leadership-related learnings derived from a catalytic experience and any connection between these learnings, personal leadership and leadership in an organisational context.Motivation fo...

  11. Application of 3-Methyl-2-vinylindoles in Catalytic Asymmetric Povarov Reaction: Diastereo- and Enantioselective Synthesis of Indole-Derived Tetrahydroquinolines.

    Science.gov (United States)

    Dai, Wei; Jiang, Xiao-Li; Tao, Ji-Yu; Shi, Feng

    2016-01-01

    The first application of 3-methyl-2-vinylindoles in catalytic asymmetric Povarov reactions has been established via the three-component reactions of 3-methyl-2-vinylindoles, aldehydes, and anilines in the presence of chiral phosphoric acid, providing easy access to chiral indole-derived tetrahydroquinolines with three contiguous stereogenic centers at high yields (up to 99%) and with excellent diastereo- and enantioselectivities (all >95:5 dr, up to 96% ee). This mode of catalytic asymmetric three-component reaction offers a step-economic and atom-economic strategy for accessing enantioenriched indole-derived tetrahydroquinolines with structural diversity and complexity. PMID:26652222

  12. In-situ observations of catalytic surface reactions with soft x-rays under working conditions

    Science.gov (United States)

    Toyoshima, Ryo; Kondoh, Hiroshi

    2015-03-01

    Catalytic chemical reactions proceeding on solid surfaces are an important topic in fundamental science and industrial technologies such as energy conversion, pollution control and chemical synthesis. Complete understanding of the heterogeneous catalysis and improving its efficiency to an ultimate level are the eventual goals for many surface scientists. Soft x-ray is one of the prime probes to observe electronic and structural information of the target materials. Most studies in surface science using soft x-rays have been performed under ultra-high vacuum conditions due to the technical limitation, though the practical catalytic reactions proceed under ambient pressure conditions. However, recent developments of soft x-ray based techniques operating under ambient pressure conditions have opened a door to the in-situ observation of materials under realistic environments. The near-ambient-pressure x-ray photoelectron spectroscopy (NAP-XPS) using synchrotron radiation enables us to observe the chemical states of surfaces of condensed matters under the presence of gas(es) at elevated pressures, which has been hardly conducted with the conventional XPS technique. Furthermore, not only the NAP-XPS but also ambient-pressure compatible soft x-ray core-level spectroscopies, such as near-edge absorption fine structure (NEXAFS) and x-ray emission spectroscopy (XES), have been significantly contributing to the in-situ observations. In this review, first we introduce recent developments of in-situ observations using soft x-ray techniques and current status. Then we present recent new findings on catalytically active surfaces using soft x-ray techniques, particularly focusing on the NAP-XPS technique. Finally we give a perspective on the future direction of this emerging technique.

  13. A New Reaction for Kinetic Spetrophotometric Determination of Trace Ruthenium--Catalytic Oxidation of Methyl Green by Bromate

    Institute of Scientific and Technical Information of China (English)

    ZHOU Zhi-rong; XU Qiong; XIONG Yan; WEI Jia-wen

    2006-01-01

    A sensitive catalytic spectrophotometric method for the determination of ruthenium (Ⅲ) has been developed, based on its catalytic effect on the oxidation reaction of methyl green with potassium bromate in acid solution medium at 100 ℃. The above reaction is followed spectrophotometrically by measuring the decrease in the absorbance at 625 nm for the catalytic reaction of methyl green. The calibration curve for the recommended reaction-rate method was linear in the concentration range over 0.00-0.80 μg/L and the detection limit of the method for Ru (Ⅲ) is 0.006μg/L. Almost no foreign ions interfered in the determination at less than 25-fold concentration of Ru (Ⅲ). The method is highly sensitive, more selective and very stable, and has been successfully applied for the determination of trace ruthenium in some ores and metallurgy products.

  14. Nanosheet-enhanced asymmetric induction of chiral α-amino acids in catalytic aldol reaction.

    Science.gov (United States)

    Zhao, Li-Wei; Shi, Hui-Min; Wang, Jiu-Zhao; He, Jing

    2012-11-26

    An efficient ligand design strategy towards boosting asymmetric induction was proposed, which simply employed inorganic nanosheets to modify α-amino acids and has been demonstrated to be effective in vanadium-catalyzed epoxidation of allylic alcohols. Here, the strategy was first extended to zinc-catalyzed asymmetric aldol reaction, a versatile bottom-up route to make complex functional compounds. Zinc, the second-most abundant transition metal in humans, is an environment-friendly catalytic center. The strategy was then further proved valid for organocatalyzed metal-free asymmetric catalysis, that is, α-amino acid catalyzed asymmetric aldol reaction. Visible improvement of enantioselectivity was experimentally achieved irrespective of whether the nanosheet-attached α-amino acids were applied as chiral ligands together with catalytic Zn(II) centers or as chiral catalysts alone. The layered double hydroxide nanosheet was clearly found by theoretical calculations to boost ee through both steric and H-bonding effects; this resembles the role of a huge and rigid substituent. PMID:23074138

  15. NO2 Catalytic Decomposition - from Laboratory Experiment to Industry Reactor

    Czech Academy of Sciences Publication Activity Database

    Obalová, L.; Jirátová, Květa; Kovanda, F.

    Kraków : Wydawnictwo Uniwersitetu Jagiellonskiego, 2011, s. 97. ISBN 978-83-233-3249-7. [International Symposium on Nitrogen Oxides Emission Abatement NOEA 2011. Zakopane (PL), 04.09.2011-07.09.2011] R&D Projects: GA TA ČR TA01020336 Institutional research plan: CEZ:AV0Z40720504 Keywords : catalytic decomposition of CO2 * reactor * kinetic data Subject RIV: CI - Industrial Chemistry, Chemical Engineering

  16. Asymmetric catalytic cascade reactions for constructing diverse scaffolds and complex molecules.

    Science.gov (United States)

    Wang, Yao; Lu, Hong; Xu, Peng-Fei

    2015-07-21

    With the increasing concerns about chemical pollution and sustainability of resources, among the significant challenges facing synthetic chemists are the development and application of elegant and efficient methods that enable the concise synthesis of natural products, drugs, and related compounds in a step-, atom- and redox-economic manner. One of the most effective ways to reach this goal is to implement reaction cascades that allow multiple bond-forming events to occur in a single vessel. This Account documents our progress on the rational design and strategic application of asymmetric catalytic cascade reactions in constructing diverse scaffolds and synthesizing complex chiral molecules. Our research is aimed at developing robust cascade reactions for the systematic synthesis of a range of interesting molecules that contain structural motifs prevalent in natural products, pharmaceuticals, and biological probes. The strategies employed to achieve this goal can be classified into three categories: bifunctional base/Brønsted acid catalysis, covalent aminocatalysis/N-heterocyclic carbene catalysis, and asymmetric organocatalytic relay cascades. By the use of rationally designed substrates with properly reactive sites, chiral oxindole, chroman, tetrahydroquinoline, tetrahydrothiophene, and cyclohexane scaffolds were successfully assembled under bifunctional base/Brønsted acid catalysis from simple and readily available substances such as imines and nitroolefins. We found that some of these reactions are highly efficient since catalyst loadings as low as 1 mol % can promote the multistep sequences affording complex architectures with high stereoselectivities and yields. Furthermore, one of the bifunctional base/Brønsted acid-catalyzed cascade reactions for the synthesis of chiral cyclohexanes has been used as a key step in the construction of the tetracyclic core of lycorine-type alkaloids and the formal synthesis of α-lycorane. Guided by the principles of

  17. An Analytical Framework for Studying Small-Number Effects in Catalytic Reaction Networks: A Probability Generating Function Approach to Chemical Master Equations.

    Science.gov (United States)

    Nakagawa, Masaki; Togashi, Yuichi

    2016-01-01

    Cell activities primarily depend on chemical reactions, especially those mediated by enzymes, and this has led to these activities being modeled as catalytic reaction networks. Although deterministic ordinary differential equations of concentrations (rate equations) have been widely used for modeling purposes in the field of systems biology, it has been pointed out that these catalytic reaction networks may behave in a way that is qualitatively different from such deterministic representation when the number of molecules for certain chemical species in the system is small. Apart from this, representing these phenomena by simple binary (on/off) systems that omit the quantities would also not be feasible. As recent experiments have revealed the existence of rare chemical species in cells, the importance of being able to model potential small-number phenomena is being recognized. However, most preceding studies were based on numerical simulations, and theoretical frameworks to analyze these phenomena have not been sufficiently developed. Motivated by the small-number issue, this work aimed to develop an analytical framework for the chemical master equation describing the distributional behavior of catalytic reaction networks. For simplicity, we considered networks consisting of two-body catalytic reactions. We used the probability generating function method to obtain the steady-state solutions of the chemical master equation without specifying the parameters. We obtained the time evolution equations of the first- and second-order moments of concentrations, and the steady-state analytical solution of the chemical master equation under certain conditions. These results led to the rank conservation law, the connecting state to the winner-takes-all state, and analysis of 2-molecules M-species systems. A possible interpretation of the theoretical conclusion for actual biochemical pathways is also discussed. PMID:27047384

  18. In situ generation of electron acceptor for photoelectrochemical biosensing via hemin-mediated catalytic reaction.

    Science.gov (United States)

    Zang, Yang; Lei, Jianping; Zhang, Lei; Ju, Huangxian

    2014-12-16

    A novel photoelectrochemical sensing strategy is designed for DNA detection on the basis of in situ generation of an electron acceptor via the catalytic reaction of hemin toward H2O2. The photoelectrochemical platform was established by sequential assembly of near-infrared CdTe quantum dots, capture DNA, and a hemin-labeled DNA probe to form a triple-helix molecular beacon (THMB) structure on an indium tin oxide electrode. According to the highly catalytic capacity of hemin toward H2O2, a photoelectrochemical mechanism was then proposed, in which the electron acceptor of O2 was in situ-generated on the electrode surface, leading to the enhancement of the photocurrent response. The utilization of CdTe QDs can extend the absorption edge to the near-infrared band, resulting in an increase in the light-to-electricity efficiency. After introducing target DNA, the THMB structure is disassembled and releases hemin and, thus, quenches the photocurrent. Under optimized conditions, this biosensor shows high sensitivity with a linear range from 1 to 1000 pM and detection limit of 0.8 pM. Moreover, it exhibits good performance of excellent selectivity, high stability, and acceptable fabrication reproducibility. This present strategy opens an alternative avenue for photoelectrochemical signal transduction and expands the applications of hemin-based materials in photoelectrochemical biosensing and clinical diagnosis. PMID:25393151

  19. Paramagnetic relaxation enhancement solid-state NMR studies of heterogeneous catalytic reaction over HY zeolite using natural abundance reactant.

    Science.gov (United States)

    Zhou, Lei; Li, Shenhui; Su, Yongchao; Li, Bojie; Deng, Feng

    2015-01-01

    Paramagnetic relaxation enhancement solid-state NMR (PRE ssNMR) technique was used to investigate catalytic reaction over zeolite HY. After introducing paramagnetic Cu(II) ions into the zeolite, the enhancement of longitudinal relaxation rates of nearby nuclei, i.e.(29)Si of the framework and (13)C of the absorbents, was measured. It was demonstrated that the PRE ssNMR technique facilitated the fast acquisition of NMR signals to monitor the heterogeneous catalytic reaction (such as acetone to hydrocarbon) using natural abundance reactants. PMID:25616847

  20. Palladium nanoparticle anchored polyphosphazene nanotubes: preparation and catalytic activity on aryl coupling reactions

    Indian Academy of Sciences (India)

    V Devi; A Ashok Kumar; S Sankar; K Dinakaran

    2015-06-01

    Highly accessible-supported palladium (Pd) nanoparticles anchored polyphosphazene (PPZ) nanotubes (NTs) having average diameter of 120 nm were synthesized rapidly at room temperature and homogeneously decorated with Pd nanoparticles. The resultant PPZ–Pd nanocomposites were morphologically and structurally characterized by means of transmission electron microscope equipped with energy-dispersive X-ray spectroscopy and X-ray diffraction analysis. Characterization results showed that the Pd nanoparticles with good dispersibility could be well anchored onto the surfaces of the PPZ NTs. The PPZ–Pd NTs show enhanced catalytic activity for the Suzuki coupling of aryl bromides with arylboronic acid. In addition, these PPZ–Pd NTs show excellent behaviour as reusable catalysts of the Suzuki and Heck coupling reactions.

  1. Spatially orthogonal chemical functionalization of a hierarchical pore network for catalytic cascade reactions

    Science.gov (United States)

    Parlett, Christopher M. A.; Isaacs, Mark A.; Beaumont, Simon K.; Bingham, Laura M.; Hondow, Nicole S.; Wilson, Karen; Lee, Adam F.

    2016-02-01

    The chemical functionality within porous architectures dictates their performance as heterogeneous catalysts; however, synthetic routes to control the spatial distribution of individual functions within porous solids are limited. Here we report the fabrication of spatially orthogonal bifunctional porous catalysts, through the stepwise template removal and chemical functionalization of an interconnected silica framework. Selective removal of polystyrene nanosphere templates from a lyotropic liquid crystal-templated silica sol-gel matrix, followed by extraction of the liquid crystal template, affords a hierarchical macroporous-mesoporous architecture. Decoupling of the individual template extractions allows independent functionalization of macropore and mesopore networks on the basis of chemical and/or size specificity. Spatial compartmentalization of, and directed molecular transport between, chemical functionalities affords control over the reaction sequence in catalytic cascades; herein illustrated by the Pd/Pt-catalysed oxidation of cinnamyl alcohol to cinnamic acid. We anticipate that our methodology will prompt further design of multifunctional materials comprising spatially compartmentalized functions.

  2. Direct Catalytic Asymmetric Mannich-Type Reaction of α- and β-Fluorinated Amides.

    Science.gov (United States)

    Brewitz, Lennart; Arteaga, Fernando Arteaga; Yin, Liang; Alagiri, Kaliyamoorthy; Kumagai, Naoya; Shibasaki, Masakatsu

    2015-12-23

    The last two decades have witnessed the emergence of direct enolization protocols providing atom-economical and operationally simple methods to use enolates for stereoselective C-C bond-forming reactions, eliminating the inherent drawback of the preformation of enolates using stoichiometric amounts of reagents. In its infancy, direct enolization relied heavily on the intrinsic acidity of the latent enolates, and the reaction scope was limited to readily enolizable ketones and aldehydes. Recent advances in this field enabled the exploitation of carboxylic acid derivatives for direct enolization, offering expeditious access to synthetically versatile chiral building blocks. Despite the growing demand for enantioenriched fluorine-containing small molecules, α- and β-fluorinated carbonyl compounds have been neglected in direct enolization chemistry because of the competing and dominating defluorination pathway. Herein we present a comprehensive study on direct and highly stereoselective Mannich-type reactions of α- and β-fluorine-functionalized 7-azaindoline amides that rely on a soft Lewis acid/hard Brønsted base cooperative catalytic system to guarantee an efficient enolization while suppressing undesired defluorination. This protocol contributes to provide a series of fluorinated analogs of enantioenriched β-amino acids for medicinal chemistry. PMID:26652911

  3. Phosphinocyclodextrins as confining units for catalytic metal centres. Applications to carbon–carbon bond forming reactions

    Directory of Open Access Journals (Sweden)

    Matthieu Jouffroy

    2014-10-01

    Full Text Available The capacity of two cavity-shaped ligands, HUGPHOS-1 and HUGPHOS-2, to generate exclusively singly phosphorus-ligated complexes, in which the cyclodextrin cavity tightly wraps around the metal centre, was explored with a number of late transition metal cations. Both cyclodextrin-derived ligands were assessed in palladium-catalysed Mizoroki–Heck coupling reactions between aryl bromides and styrene on one hand, and the rhodium-catalysed asymmetric hydroformylation of styrene on the other hand. The inability of both chiral ligands to form standard bis(phosphine complexes under catalytic conditions was established by high-pressure NMR studies and shown to have a deep impact on the two carbon–carbon bond forming reactions both in terms of activity and selectivity. For example, when used as ligands in the rhodium-catalysed hydroformylation of styrene, they lead to both high isoselectivity and high enantioselectivity. In the study dealing with the Mizoroki–Heck reactions, comparative tests were carried out with WIDEPHOS, a diphosphine analogue of HUGPHOS-2.

  4. Catalytic activity of nuclease P1: Experiment and theory

    International Nuclear Information System (INIS)

    Nuclease P1 from Penicillium citrinum is a zinc dependent glyco-enzyme that recognizes single stranded DNA and RNA as substrates and hydrolyzes the phosphate ester bond. Nuclease Pl seems to recognize particular conformations of the phosphodiester backbone and shows significant variation in the rate of hydrolytic activity depending upon which nucleosides are coupled by the phosphodiester bond. The efficiency of nuclease Pl in hydrolyzing the phosphodiester bonds of a substrate can be altered by modifications to one of the substrate bases induced by ionizing radiation or oxidative stress. Measurements have been made of the effect of several radiation induced lesions on the catalytic rate of nuclease Pl. A model of the structure of the enzyme has been constructed in order to better understand the binding and activity of this enzyme on various ssDNA substrates

  5. Reaction intermediates in the catalytic mechanism of Escherichia coli MutY DNA glycosylase.

    Science.gov (United States)

    Manuel, Raymond C; Hitomi, Kenichi; Arvai, Andrew S; House, Paul G; Kurtz, Andrew J; Dodson, M L; McCullough, Amanda K; Tainer, John A; Lloyd, R Stephen

    2004-11-01

    The Escherichia coli adenine DNA glycosylase, MutY, plays an important role in the maintenance of genomic stability by catalyzing the removal of adenine opposite 8-oxo-7,8-dihydroguanine or guanine in duplex DNA. Although the x-ray crystal structure of the catalytic domain of MutY revealed a mechanism for catalysis of the glycosyl bond, it appeared that several opportunistically positioned lysine side chains could participate in a secondary beta-elimination reaction. In this investigation, it is established via site-directed mutagenesis and the determination of a 1.35-A structure of MutY in complex with adenine that the abasic site (apurinic/apyrimidinic) lyase activity is alternatively regulated by two lysines, Lys142 and Lys20. Analyses of the crystallographic structure also suggest a role for Glu161 in the apurinic/apyrimidinic lyase chemistry. The beta-elimination reaction is structurally and chemically uncoupled from the initial glycosyl bond scission, indicating that this reaction occurs as a consequence of active site plasticity and slow dissociation of the product complex. MutY with either the K142A or K20A mutation still catalyzes beta and beta-delta elimination reactions, and both mutants can be trapped as covalent enzyme-DNA intermediates by chemical reduction. The trapping was observed to occur both pre- and post-phosphodiester bond scission, establishing that both of these intermediates have significant half-lives. Thus, the final spectrum of DNA products generated reflects the outcome of a delicate balance of closely related equilibrium constants. PMID:15326180

  6. Catalytic effects of Lewis acids on 1,3-DC reaction: A luminescent study

    Energy Technology Data Exchange (ETDEWEB)

    Chaudhuri, Tandrima, E-mail: tanchem_bu@yahoo.co.in [Department of Chemistry, Dr. Bhupendra Nath Dutta Smriti Mahavidyalaya, Hatgobidopur, Burdwan-713407 (India); Department of Chemistry, University of Burdwan, Burdwan-713104 (India); Banerjee, Manas, E-mail: manasban@rediffmail.com [Department of Chemistry, University of Burdwan, Burdwan-713104 (India)

    2012-06-15

    Competitive coordination by the nitrone and the dipolarophile to the Lewis acid catalysts like metal triflates controls the acceleration and deceleration of the catalyzed 1,3-dipolar cycloaddition reactions as compared to the uncatalyzed one. This fact has been established through variation in steady state fluorescence of the substrates in presence of catalyst. Li{sup +} found to catalyze both the cycloaddition between {alpha}-p-chlorophenyl-N-phenyl nitrone (N1) and Benzylidene acetophenone (D1) as well as between N1 and 3-Phenyl-1-pyridin-2-yl-propenone (D2) efficiently. While Yb{sup 3+} can catalyze only the cycloaddition between N1 and D2. The experimental findings have been rationalized on the basis of DFT calculations and analysis based on the frontier molecular orbital energies and relative electrophilicity of the reactants. - Highlights: Black-Right-Pointing-Pointer A fluorescence study of catalytic effect of an 1,3-DC reaction between an acyclic nitrone (N1) with two different dipolarophiles D1 and D2 in toluene. Black-Right-Pointing-Pointer Yb{sup 3+} quenches the fluorescence intensity of N1 more efficiently than Li{sup +}. Black-Right-Pointing-Pointer Li{sup +} shows better interaction with both the two dipolarophiles D1 and D2 hence can accelerate the 1,3-DC reaction rate between N1 and D. Black-Right-Pointing-Pointer Yb{sup 3+} can only be used as good catalyst for the 1,3-DC reaction between N1 and D2. Black-Right-Pointing-Pointer Spectroscopic findings are rationalized with DFT calculated electrophilicity indices of the reactants.

  7. Catalytic effects of Lewis acids on 1,3-DC reaction: A luminescent study

    International Nuclear Information System (INIS)

    Competitive coordination by the nitrone and the dipolarophile to the Lewis acid catalysts like metal triflates controls the acceleration and deceleration of the catalyzed 1,3-dipolar cycloaddition reactions as compared to the uncatalyzed one. This fact has been established through variation in steady state fluorescence of the substrates in presence of catalyst. Li+ found to catalyze both the cycloaddition between α-p-chlorophenyl-N-phenyl nitrone (N1) and Benzylidene acetophenone (D1) as well as between N1 and 3-Phenyl-1-pyridin-2-yl-propenone (D2) efficiently. While Yb3+ can catalyze only the cycloaddition between N1 and D2. The experimental findings have been rationalized on the basis of DFT calculations and analysis based on the frontier molecular orbital energies and relative electrophilicity of the reactants. - Highlights: ► A fluorescence study of catalytic effect of an 1,3-DC reaction between an acyclic nitrone (N1) with two different dipolarophiles D1 and D2 in toluene. ► Yb3+ quenches the fluorescence intensity of N1 more efficiently than Li+. ► Li+ shows better interaction with both the two dipolarophiles D1 and D2 hence can accelerate the 1,3-DC reaction rate between N1 and D. ► Yb3+ can only be used as good catalyst for the 1,3-DC reaction between N1 and D2. ► Spectroscopic findings are rationalized with DFT calculated electrophilicity indices of the reactants.

  8. PREPARATION, CHARACTERIZATION AND CATALYTIC ACTIVITY OF CuO/TS-1 ON BENZENE HYDROXYLATION REACTION

    Directory of Open Access Journals (Sweden)

    Nuni Widiarti

    2011-11-01

    Full Text Available CuO/TS-1 catalysts have been prepared and tested in the benzene hydroxylation. TS-1 was synthesized by hydrothermalmethod, while CuO/TS-1 was prepared by impregnation method using Cu(NO2.3H2O as precursor. Catalysts werecharacterized by using X-ray diffraction (XRD, infrared spectroscopy (IR, and N2 adsorption-desorption techniques.The catalytic activity was tested in the hydroxylation reaction of benzene. The products were analyzed using gaschromatography. Catalyst characterization by XRD and IR techniques have showed that the catalyst structure was aMFI type of zeolite. XRD pattern have showed the orthorombic structure and indicated the presence of CuOaggregation. The results of the pyridine adsorption have found that the acidity of TS-1 and CuO/TS-1 were a Lewis acidand it’s increased with an increasing amount of CuO loading. The results of nitrogen adsorption analysis have showeddecreasing of surface areas of catalyst with increasing amount of CuO loading. The optimum conditions of benzenehydroxylation was observed by 1%CuO/TS-1 catalyst at 70 °C, reaction time 2 h and acetic acid as the solvent yielded27.6% of phenol with phenol selectivity was 75.5%.

  9. Catalytic hydroliquefaction of coal: about the methodology in batch experiments

    Energy Technology Data Exchange (ETDEWEB)

    Besson, M.; Bacaud, R.; Charcosset, H.; Cebolla-Burillo, V.; Oberson, M.

    1986-03-01

    The results of catalytic hydroliquefaction under batch conditions depend on a large number of variables. The present results concern a few of these variables, in particular the influence of the catalyst concentration, of the mode of sulfidation or (and) of introduction of the catalyst in the coal/solvent mixture, and of the nature of the model compound solvent. The results indicate that increasing the concentration of catalyst increase the conversion of coal into toluene soluble products and the hydrogen consumption but has a small effect on oil formation. An inhibition of the figst fractions of a NiMo/Al/sub 2/O/sub 3/ catalyst added is shown. Strong effects of the sulfiding mode of an iron oxide catalyst, and of the temperature of introduction of the iron oxide into the autoclave are observed relative to the hydrogenation activity of the iron catalyst, when at the same time there is no influence on coal conversions. The replacement of tetralin by a non-donor solvent, 1-methylnaphthalene, suggests that the direct hydrogen transfer process from molecular hydrogen to coal fragment radicals on the catalyst surface may be important. 9 tabs., 4 firs., 16 refs.

  10. Catalytic Upgrading of Biomass-Derived Compounds via C-C Coupling Reactions. Computational and Experimental Studies of Acetaldehyde and Furan Reactions in HZSM-5

    Energy Technology Data Exchange (ETDEWEB)

    Liu, Cong [Argonne National Lab. (ANL), Argonne, IL (United States); Evans, Tabitha J. [National Renewable Energy Lab. (NREL), Golden, CO (United States); Cheng, Lei [Argonne National Lab. (ANL), Argonne, IL (United States); Nimlos, Mark R. [National Renewable Energy Lab. (NREL), Golden, CO (United States); Mukarakate, Calvin [National Renewable Energy Lab. (NREL), Golden, CO (United States); Robichaud, David J. [National Renewable Energy Lab. (NREL), Golden, CO (United States); Assary, Rajeev S. [Argonne National Lab. (ANL), Argonne, IL (United States); Curtiss, Larry A. [Argonne National Lab. (ANL), Argonne, IL (United States)

    2015-10-02

    These catalytic C–C coupling and deoxygenation reactions are essential for upgrading of biomass-derived oxygenates to fuel-range hydrocarbons. Detailed understanding of mechanistic and energetic aspects of these reactions is crucial to enabling and improving the catalytic upgrading of small oxygenates to useful chemicals and fuels. Using periodic density functional theory (DFT) calculations, we have investigated the reactions of furan and acetaldehyde in an HZSM-5 zeolite catalyst, a representative system associated with the catalytic upgrading of pyrolysis vapors. Comprehensive energy profiles were computed for self-reactions (i.e., acetaldehyde coupling and furan coupling) and cross-reactions (i.e., acetaldehyde + furan) of this representative mixture. Major products proposed from the computations are further confirmed using temperature controlled mass spectra measurements. Moreover, the computational results show that furan interacts with acetaldehyde in HZSM-5 via an alkylation mechanism, which is more favorable than the self-reactions, indicating that mixing furans with aldehydes could be a promising approach to maximize effective C–C coupling and dehydration while reducing the catalyst deactivation (e.g., coke formation) from aldehyde condensation.

  11. Catalytic Studies Featuring Palladium(II Benzoylthiourea Derivative as Catalyst in Sonogashira Reaction

    Directory of Open Access Journals (Sweden)

    Wan M. Khairul

    2014-10-01

    Full Text Available A benzoylthiourea derivative (LTU and its metal complexation of palladium(II chloride (MLTU has been successfully synthesized and characterized via typical spectroscopic and analytical techniques namely IR, 1H and 13C Nuclear Magnetic Resonance, UV-Visible and Gas Chromatography Flame Ionization Detector (GC-FID. The Infrared spectrum for LTU shows four significant bands of interest namely ν(N-H, ν(C=O, ν(C-N and ν(C=S and the values were observed within the range. The 1H NMR spectrum for the compound shows expected protons for N-H at δH 10.95 ppm and δH 11.15 ppm while the 13C NMR spectrum shows resonances of carbonyl (C=O carbon and thiones (C=S at δC 168.26 ppm and δC 180.56 ppm, respectively. From UV-Vis spectrum, it shows the presence of n-pi* and pi→pi*electronic transitions which are expected to be attributed from the phenyl ring, carbonyl (C=O and thiones (C=S chromophores. Complexation of LTU with palladium(II chloride was done to afford MLTU which in turn, was tested as homogeneous catalyst in Sonogashira cross-coupling reaction. The reaction was monitored by GC-FID at 6 hours reaction period. The percentage conversion of 4-bromoacetophenone to the coupled product was 75.73% indicated that MLTU can act as an ideal potential catalyst in the Sonogashira reaction. © 2014 BCREC UNDIP. All rights reservedReceived: 14th May 2014; Revised: 30th August 2014; Accepted: 3rd September 2014 How to Cite: Khairul, W.M., Faisol, S.L.M., Jasman, S.M., Shamsuddin, M. (2014. Catalytic Studies Featuring Palladium(II Benzoylthiourea Derivative as Catalyst in Sonogashira Reaction. Bulletin of Chemical Reaction Engineering & Catalysis, 9 (3: 241-248 (doi:10.9767/bcrec.9.3.6880.241-248Permalink/DOI: http://dx.doi.org/10.9767/bcrec.9.3.6880.241-248

  12. Structural Basis on the Catalytic Reaction Mechanism of Novel 1,2-Alpha L-Fucosidase (AFCA) From Bifidobacterium Bifidum

    Energy Technology Data Exchange (ETDEWEB)

    Nagae, M.; Tsuchiya, A.; Katayama, T.; Yamamoto, K.; Wakatsuki, S.; Kato, R.

    2009-06-03

    1,2-alpha-L-fucosidase (AfcA), which hydrolyzes the glycosidic linkage of Fucalpha1-2Gal via an inverting mechanism, was recently isolated from Bifidobacterium bifidum and classified as the first member of the novel glycoside hydrolase family 95. To better understand the molecular mechanism of this enzyme, we determined the x-ray crystal structures of the AfcA catalytic (Fuc) domain in unliganded and complexed forms with deoxyfuconojirimycin (inhibitor), 2'-fucosyllactose (substrate), and L-fucose and lactose (products) at 1.12-2.10 A resolution. The AfcA Fuc domain is composed of four regions, an N-terminal beta region, a helical linker, an (alpha/alpha)6 helical barrel domain, and a C-terminal beta region, and this arrangement is similar to bacterial phosphorylases. In the complex structures, the ligands were buried in the central cavity of the helical barrel domain. Structural analyses in combination with mutational experiments revealed that the highly conserved Glu566 probably acts as a general acid catalyst. However, no carboxylic acid residue is found at the appropriate position for a general base catalyst. Instead, a water molecule stabilized by Asn423 in the substrate-bound complex is suitably located to perform a nucleophilic attack on the C1 atom of L-fucose moiety in 2'-fucosyllactose, and its location is nearly identical near the O1 atom of beta-L-fucose in the products-bound complex. Based on these data, we propose and discuss a novel catalytic reaction mechanism of AfcA.

  13. Classical Keggin Intercalated into Layered Double Hydroxides: Facile Preparation and Catalytic Efficiency in Knoevenagel Condensation Reactions.

    Science.gov (United States)

    Jia, Yueqing; Fang, Yanjun; Zhang, Yingkui; Miras, Haralampos N; Song, Yu-Fei

    2015-10-12

    The family of polyoxometalate (POM) intercalated layered double hydroxide (LDH) composite materials has shown great promise for the design of functional materials with numerous applications. It is known that intercalation of the classical Keggin polyoxometalate (POM) of [PW12 O40 ](3-) (PW12 ) into layered double hydroxides (LDHs) is very unlikely to take place by conventional ion exchange methods due to spatial and geometrical restrictions. In this paper, such an intercalated compound of Mg0.73 Al0.22 (OH)2 [PW12 O40 ]0.04 ⋅0.98 H2 O (Mg3 Al-PW12 ) has been successfully obtained by applying a spontaneous flocculation method. The Mg3 Al-PW12 has been fully characterized by using a wide range of methods (XRD, SEM, TEM, XPS, EDX, XPS, FT-IR, NMR, BET). XRD patterns of Mg3 Al-PW12 exhibit no impurity phase usually observed next to the (003) diffraction peak. Subsequent application of the Mg3 Al-PW12 as catalyst in Knoevenagel condensation reactions of various aldehydes and ketones with Z-CH2 -Z' type substrates (ethyl cyanoacetate and malononitrile) at 60 °C in mixed solvents (V2-propanol :Vwater =2:1) demonstrated highly efficient catalytic activity. The synergistic effect between the acidic and basic sites of the Mg3 Al-PW12 composite proved to be crucial for the efficiency of the condensation reactions. Additionally, the Mg3 Al-PW12 -catalyzed Knoevenagel condensation of benzaldehyde with ethyl cyanoacetate demonstrated the highest turnover number (TON) of 47 980 reported so far for this reaction. PMID:26337902

  14. β-Alanine-DBU" A Highly Efficient Catalytic System forKnoevenageI-Doebner Reaction under Mild Conditionsβ-Alanine-DBU" A Highly Efficient Catalytic System forKnoevenageI-Doebner Reaction under Mild Conditions

    Institute of Scientific and Technical Information of China (English)

    祝令建; 雷宁; 缪震元; 盛春泉; 庄春林; 姚建忠; 张万年

    2012-01-01

    A mild and efficient Knoevenagel-Doebner reaction from malonic acid and a wide range of aldehydes was catalyzed by a catalytic system consisting offlalanine and 1,8-diazabicyclo[5.4.0]undec-7-ene (DBU), affording the corresponding (E)-a,fl-unsaturated carboxylic acids in good to excellent yields and with high stereoselectivity. The advantage of the method is that the reaction could proceed smoothly at ambient temperature so that it can tolerate a variety of functional groups and avoid unnecessary side reactions.

  15. Catalytic activities enhanced by abundant structural defects and balanced N distribution of N-doped graphene in oxygen reduction reaction

    Science.gov (United States)

    Bai, Xiaogong; Shi, Yantao; Guo, Jiahao; Gao, Liguo; Wang, Kai; Du, Yi; Ma, Tingli

    2016-02-01

    N-doped graphene (NG) is a promising candidate for oxygen reduction reaction (ORR) in the cathode of fuel cells. However, the catalytic activity of NG is lower than that of commercial Pt/C in alkaline and acidic media. In this study, NG samples were obtained using urea as N source. The structural defects and N distribution in the samples were adjusted by regulating the pyrolysis temperature. The new NG type exhibited remarkable catalytic activities for ORR in both alkaline and acidic media.

  16. Accelerated Catalytic Fenton Reaction with Traces of Iron: An Fe-Pd-Multicatalysis Approach.

    Science.gov (United States)

    Georgi, Anett; Velasco Polo, Miriam; Crincoli, Klara; Mackenzie, Katrin; Kopinke, Frank-Dieter

    2016-06-01

    An accelerated catalytic Fenton (ACF) reaction was developed based upon a multicatalysis approach, facilitating efficient contaminant oxidation at trace levels of dissolved iron. Beside the Fe(II)/H2O2 catalyst/oxidant pair for production of OH-radicals, the ACF system contains Pd/H2 as catalyst/reductant pair for fast reduction of Fe(III) back to Fe(II) which accelerates the Fenton cycle and leads to faster contaminant degradation. By this means, the concentration of the dissolved iron catalyst can be reduced to trace levels (1 mg L(-1)) below common discharge limits, thus eliminating the need for iron sludge removal, which is one of the major drawbacks of conventional Fenton processes. ACF provides fast degradation of the model contaminant methyl tert-butyl ether (MTBE, C0 = 0.17 mM) with a half-life of 11 min with 1 mg L(-1) dissolved iron, 500 mg L(-1) H2O2, 5 mg L(-1) Pd (as suspended Pd/Al2O3 catalyst) and 0.1 MPa H2, pH 3. The effects of pH, H2 partial pressure and H2O2 concentration on MTBE degradation rates were studied. Results on kinetic deuterium isotope effect and quenching studies are in conformity with OH-radicals as main oxidant. The heterogeneous Pd/Al2O3 catalyst was reused within six cycles without significant loss in activity. PMID:27167833

  17. Novel plasma catalytic reaction for structural-controlled growth of graphene and graphene nanoribbon

    Science.gov (United States)

    Kato, Toshiaki

    2013-09-01

    An advanced plasma chemical vapor deposition (CVD) method has outstanding advantages for the structural-controlled growth and functionalization of carbon nanotubes (CNTs) and graphene. Graphene nanoribbons combine the unique electronic and spin properties of graphene with a transport gap. This makes them an attractive candidate material for the channels of next-generation transistors. However, the reliable site and alignment control of nanoribbons with high on/off current ratios remains a challenge. We have developed a new, simple, scalable method based on novel plasma catalytic reaction for directly fabricating narrow (23 nm) graphene nanoribbon devices with a clear transport gap (58.5 meV) and a high on/off ratio (10000). Indeed, graphene nanoribbons can be grown at any desired position on an insulating substrate without any post-growth treatment, and large-scale, two- and three dimensional integration of graphene nanoribbon devices should be realizable, thereby accelerating the practical evolution of graphene nanoribbon-based electrical applications.

  18. A chemiluminescence assay for L-histidine based on controlled DNAzyme catalytic reactions on magnetic microparticles

    International Nuclear Information System (INIS)

    We describe a chemiluminescence (CL) assay for L-histidine that is based on the use of DNAzyme covalently immobilized on 1.5-μm sized magnetic beads. On addition of a substrate labeled with a CL reagent, the DNAzyme and substrate form a stable duplex by allosteric synergetic stabilization of each duplex. If L-histidine is added to this system, self-cleavage of the substrate occurs through catalytic reaction and results in the formation of two fragments which dissociate from the beads. After removal of the magnetic beads, the labeled fragments can be detected by CL whose intensity is linearly related to the concentration of L-histidine in the 1.0 to 1,000 nM range. The detection limit is 0.3 nM, and the RSD is 3.4 % at a 50 nM level (n = 9). The method has been successfully applied to the determination of L-histidine in spiked human serum samples and holds promise as a widely applicable general platform for DNAzyme-based CL detection of small organic molecules and of metal ions. (author)

  19. Study of the dynamics of the MoO2-Mo2C system for catalytic partial oxidation reactions

    Science.gov (United States)

    Cuba Torres, Christian Martin

    On a global scale, the energy demand is largely supplied by the combustion of non-renewable fossil fuels. However, their rapid depletion coupled with environmental and sustainability concerns are the main drivers to seek for alternative energetic strategies. To this end, the sustainable generation of hydrogen from renewable resources such as biodiesel would represent an attractive alternative solution to fossil fuels. Furthermore, hydrogen's lower environmental impact and greater independence from foreign control make it a strong contender for solving this global problem. Among a wide variety of methods for hydrogen production, the catalytic partial oxidation offers numerous advantages for compact and mobile fuel processing systems. For this reaction, the present work explores the versatility of the Mo--O--C catalytic system under different synthesis methods and reforming conditions using methyl oleate as a surrogate biodiesel. MoO2 exhibits good catalytic activity and exhibits high coke-resistance even under reforming conditions where long-chain oxygenated compounds are prone to form coke. Moreover, the lattice oxygen present in MoO2 promotes the Mars-Van Krevelen mechanism. Also, it is introduced a novel beta-Mo2C synthesis by the in-situ formation method that does not utilize external H2 inputs. Herein, the MoO 2/Mo2C system maintains high catalytic activity for partial oxidation while the lattice oxygen serves as a carbon buffer for preventing coke formation. This unique feature allows for longer operation reforming times despite slightly lower catalytic activity compared to the catalysts prepared by the traditional temperature-programmed reaction method. Moreover, it is demonstrated by a pulse reaction technique that during the phase transformation of MoO2 to beta-Mo2C, the formation of Mo metal as an intermediate is not responsible for the sintering of the material wrongly assumed by the temperature-programmed method.

  20. Preparation of porous paper composites with ruthenium hydroxide and catalytic alcohol oxidation in a multiphase gas–liquid–solid reaction

    Energy Technology Data Exchange (ETDEWEB)

    Homma, Taichi [Department of Agro-Environmental Sciences, Graduate School of Bioresource and Bioenvironmental Sciences, and Biotron Application Center, Kyushu University, 6-10-1 Hakozaki, Higashi-ku, Fukuoka 812-8581 (Japan); Processing Development Research Laboratory, Kao Corporation, 2606 Akabane, Ichikai-machi, Haga-gun, Tochigi 321-3497 (Japan); Kitaoka, Takuya, E-mail: tkitaoka@agr.kyushu-u.ac.jp [Department of Agro-Environmental Sciences, Graduate School of Bioresource and Bioenvironmental Sciences, and Biotron Application Center, Kyushu University, 6-10-1 Hakozaki, Higashi-ku, Fukuoka 812-8581 (Japan)

    2014-05-01

    Highlights: • Flexible and porous paper-structured Ru(OH){sub x} catalysts were prepared successfully. • Ru(OH){sub x} catalysts were dispersed on the ceramic fiber networks of paper composites. • Catalytic oxidation of benzyl alcohol proceeded efficiently in three-phase reactions. • Paper catalysts exhibited much higher performance than conventional solid catalysts. - Abstract: In situ synthesis of ruthenium hydroxide catalysts on a microporous fiber-network structure of ceramic paper composites was achieved. The efficient catalytic oxidation of alcohol was investigated in a heterogeneous, multiphase gas–liquid–solid reaction. A simple papermaking technique and subsequent immersion in a ruthenium chloride solution allowed us to fabricate novel-concept microstructured catalysts. The paper-structured catalysts possess micropores ca. 30 μm in diameter with high porosity of ca. 90%. They exhibited much higher catalytic efficiency in the O{sub 2}-mediated oxidation in toluene of benzyl alcohol to benzaldehyde in a fixed bed external loop reactor, as compared with conventional pellet- and bead-type solid catalysts. This excellent catalytic effect is possibly attributed to the porous paper composite microstructure like microreactors.

  1. Preparation of porous paper composites with ruthenium hydroxide and catalytic alcohol oxidation in a multiphase gas–liquid–solid reaction

    International Nuclear Information System (INIS)

    Highlights: • Flexible and porous paper-structured Ru(OH)x catalysts were prepared successfully. • Ru(OH)x catalysts were dispersed on the ceramic fiber networks of paper composites. • Catalytic oxidation of benzyl alcohol proceeded efficiently in three-phase reactions. • Paper catalysts exhibited much higher performance than conventional solid catalysts. - Abstract: In situ synthesis of ruthenium hydroxide catalysts on a microporous fiber-network structure of ceramic paper composites was achieved. The efficient catalytic oxidation of alcohol was investigated in a heterogeneous, multiphase gas–liquid–solid reaction. A simple papermaking technique and subsequent immersion in a ruthenium chloride solution allowed us to fabricate novel-concept microstructured catalysts. The paper-structured catalysts possess micropores ca. 30 μm in diameter with high porosity of ca. 90%. They exhibited much higher catalytic efficiency in the O2-mediated oxidation in toluene of benzyl alcohol to benzaldehyde in a fixed bed external loop reactor, as compared with conventional pellet- and bead-type solid catalysts. This excellent catalytic effect is possibly attributed to the porous paper composite microstructure like microreactors

  2. 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

  3. Exploring the learnings derived from catalytic experiences in a leadership context

    Directory of Open Access Journals (Sweden)

    Daphna S. Horowitz

    2015-03-01

    Full Text Available Orientation: Personal leadership comprises self-awareness, authenticity, inspiration and passion. The concept of personal leadership was explored together with its relationship with leadership-related learnings derived from a catalytic experience.Research purpose: The objective of the study was to explore the leadership-related learnings derived from a catalytic experience and any connection between these learnings, personal leadership and leadership in an organisational context.Motivation for the study: Measurement of leaders’ performance remains largely focused on the results achieved. The importance of personal leadership in the corporate environment is often ignored and even questioned. Recognising that there is a relationship between personal leadership and professional leadership enables leaders to connect who they are being and what they are doing. This can enhance their leadership.Research design, approach and method: The study was conducted using a qualitative approach, specifically narrative enquiry. The sample comprised seven leaders who have had catalytic experiences in their lives. In-depth interviews were conducted and thematic analysis was used to identify themes on the leadership-related learnings gained from the leaders’catalytic experiences.Main findings: Elements of personal leadership and the processes involved in the development of personal leadership were identified. It was furthermore shown that challenging experiences serve as learning opportunities and that time for reflection is essential in this learning process.Practical/managerial implications: Leadership lessons are best learnt through experience.Using challenging experiences as learning opportunities may assist leaders in their growth and development.Contribution: Leadership effectiveness and organisational effectiveness may be enhanced by a more holistic view of leadership that includes elements of personal leadership.

  4. 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.

  5. Catalytic synthesis of 2-methylpyrazine over Cr-promoted copper based catalyst via a cyclo-dehydrogenation reaction route

    Indian Academy of Sciences (India)

    Fangli Jing; Yuanyuan Zhang; Shizhong Luo; Wei Chu; Hui Zhang; Xinyu Shi

    2010-07-01

    The cyclo-dehydrogenation of ethylene diamine and propylene glycol to 2-methylpyrazine was performed under the atmospheric conditions at 380°C. The Cr-promoted Cu-Zn/Al2O3 catalysts were prepared by impregnation method and characterized by ICP-AES, N2 adsorption/desorption, XRD, XPS, N2O chemisorption, TPR and NH3-TPD techniques. The amorphous chromium species existing in Cu-Zn-Cr/Al2O3 catalyst enhanced the dispersion of active component Cu, promoted the reduction of catalyst. Furthermore, the catalytic performance was significantly improved. The acidity of the catalyst played an important role in increasing the 2-MP selectivity. To optimize the reaction parameters, influences of different chromium content, reaction temperature, liquid hourly space velocity (LHSV), reactants molar ratio and time on stream on the product pattern were studied. The results demonstrated that addition of chromium promoter revealed satisfying catalytic activity, stability and selectivity of 2-methylpyrazine.

  6. The effect of noble metals on catalytic methanation reaction over supported Mn/Ni oxide based catalysts

    OpenAIRE

    Wan Azelee Wan Abu Bakar; Rusmidah Ali; Nurul Shafeeqa Mohammad

    2015-01-01

    Carbon dioxide (CO2) in sour natural gas can be removed using green technology via catalytic methanation reaction by converting CO2 to methane (CH4) gas. Using waste to wealth concept, production of CH4 would increase as well as creating environmental friendly approach for the purification of natural gas. In this research, a series of alumina supported manganese–nickel oxide based catalysts doped with noble metals such as ruthenium and palladium were prepared by wetness impregnation method. T...

  7. 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...

  8. High catalytic efficiency of palladium nanoparticles immobilized in a polymer membrane containing poly(ionic liquid) in Suzuki–Miyaura cross-coupling reaction

    OpenAIRE

    Gu, Yingying; Favier, Isabelle; Pradel, Christian; Gin, Douglas L.; Lahitte, Jean-Francois; Noble, Richard D.; Gómez, Montserrat; Remigy, Jean-Christophe

    2015-01-01

    The elaboration of a polymeric catalytic membrane containing palladium nanoparticles is presented. The membrane was prepared using a photo-grafting process with imidazolium-based ionic liquid monomers as modifying agent and microPES® as support membrane. Ionic liquid serves as a stabilizer and immobilizer for the catalytic species, i.e. palladium nanoparticles. The Suzuki–Miyaura cross-coupling reaction was carried out on the catalytic membrane in flow-through configuration. Complete conversi...

  9. Cage-bell Pt-Pd nanostructures with enhanced catalytic properties and superior methanol tolerance for oxygen reduction reaction

    Science.gov (United States)

    Chen, Dong; Ye, Feng; Liu, Hui; Yang, Jun

    2016-04-01

    Precisely tailoring the structure and fully making use of the components of nanoparticles are effective to enhance their catalytic performance for a given reaction. We herein demonstrate the design of cage-bell structured Pt-Pd nanoparticles, where a Pd shell is deliberately selected to enhance the catalytic property and methanol tolerance of Pt for oxygen reduction reaction. This strategy starts with the synthesis of core-shell Pt@Ag nanoparticles, followed by galvanic replacement reaction between the Ag shell and Pd2+ ions to form core-shell-shell Pt@Ag@Ag-Pd nanoparticles with a Pt core and double shells composed of Ag at inner and alloy Ag-Pd at outer, respectively. Then, the core-shell-shell templates are agitated with saturated NaCl solution to eliminate the Ag component from the double shells, leading to the formation of bimetallic Pt-Pd nanoparticles with a cage-bell structure, defined as a movable Pt core enclosed by a porous Pd shell, which show enhanced catalytic activity for oxygen reduction compared with that of the Pt seeds due to the additional catalysis from Pd shell. In addition, owing to the different diffusion behavior of methanol and oxygen molecules in the porous Pd shell, the Pt-Pd cage-bell nanostructures also exhibit superior methanol tolerant property in catalyzing the oxygen reduction.

  10. 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

  11. Enhancement in the Catalytic Activity of Pd/USY in the Heck Reaction Induced by H2 Bubbling

    Directory of Open Access Journals (Sweden)

    Miki Niwa

    2010-12-01

    Full Text Available Pd was loaded on ultra stable Y (USY zeolites prepared by steaming NH4-Y zeolite under different conditions. Heck reactions were carried out over the prepared Pd/USY. We found that H2 bubbling was effective in improving not only the catalytic activity of Pd/USY, but also that of other supported Pd catalysts and Pd(OAc2. Moreover, the catalytic activity of Pd/USY could be optimized by choosing appropriate steaming conditions for the preparation of the USY zeolites; Pd loaded on USY prepared at 873 K with 100% H2O gave the highest activity (TOF = 61,000 h−1, which was higher than that of Pd loaded on other kinds of supports. The prepared Pd/USY catalysts were applicable to the Heck reactions using various kinds of substrates including bromo- and chloro-substituted aromatic and heteroaromatic compounds. Characterization of the acid properties of the USY zeolites revealed that the strong acid site (OHstrong generated as a result of steaming had a profound effect on the catalytic activity of Pd.

  12. 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.

  13. Radiotracer experiments on lignin reactions, (1)

    International Nuclear Information System (INIS)

    Investigation of structure and reaction of lignin has been limited, because degradation of lignin to its constituent monomeric or oligomeric unit is only partially accomplished, leaving a large part of denatured core lignin beyond an object of detailed investigation. However, application of radioactive tracer technique provides immediate information about the behavior of a specific atom or specific combination of atoms in the reaction regardless of the physical state and the chemical nature of the reaction product. In this work, woody tissues containing protolignin universally or specifically labelled with 14C were prepared by administration of appropriate precursors of lignin to pine trees or shoots. Universally labelled wood tissues were obtained in good yield of radioactivity by administration of carbon dioxide-14C. In this case, however, the radioactivity was incorporated into every constituent of the tissue, separation of radioactive lignin from the other constituents was always necessary before use. Specifically labelled lignin was obtained in good yield by administration of specifically labelled phenylalanine, methionine or ferulic acid to a pine shoot. Radioactivity was shown to be incorporated into the specific carbon of protolignin according to the specific labelling of the precursors. Ferulic acid was a reliable and preferable precursor in specific labelling of protolignin and in yield of radioactivity. (auth.)

  14. TiO2-sludge carbon enhanced catalytic oxidative reaction in environmental wastewaters applications.

    Science.gov (United States)

    Athalathil, Sunil; Erjavec, Boštjan; Kaplan, Renata; Stüber, Frank; Bengoa, Christophe; Font, Josep; Fortuny, Agusti; Pintar, Albin; Fabregat, Azael

    2015-12-30

    The enhanced oxidative potential of sludge carbon/TiO2 nano composites (SNCs), applied as heterogeneous catalysts in advanced oxidation processes (AOPs), was studied. Fabrification of efficient SNCs using different methods and successful evaluation of their catalytic oxidative activity is reported for the first time. Surface modification processes of hydrothermal deposition, chemical treatment and sol-gel solution resulted in improved catalytic activity and good surface chemistry of the SNCs. The solids obtained after chemical treatment and hydrothermal deposition processes exhibit excellent crystallinity and photocatalytic activity. The highest photocatalytic rate was obtained for the material prepared using hydrothermal deposition technique, compared to other nanocomposites. Further, improved removal of bisphenol A (BPA) from aqueous phase by means of catalytic ozonation and catalytic wet air oxidation processes is achieved over the solid synthesized using chemical treatment method. The present results demonstrate that the addition of TiO2 on the surface of sludge carbon (SC) increases catalytic oxidative activity of SNCs. The latter produced from harmful sludge materials can be therefore used as cost-effective and efficient sludge derived catalysts for the removal of hazardous pollutants. PMID:26223014

  15. 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.

  16. 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.

  17. Visible to near-infrared plasmon-enhanced catalytic activity of Pd hexagonal nanoplates for the Suzuki coupling reaction

    Science.gov (United States)

    Trinh, T. Thuy; Sato, Ryota; Sakamoto, Masanori; Fujiyoshi, Yoshifumi; Haruta, Mitsutaka; Kurata, Hiroki; Teranishi, Toshiharu

    2015-07-01

    Photocatalytic conversion of solar energy to chemical energy is an efficient process in green chemistry because it facilitates room temperature chemical transformations by generating electronically excited states in photocatalysts. We report here on the robust synthesis, detailed structural characterization, and especially photocatalytic properties of plasmonic Pd hexagonal nanoplates for chemical reactions. The Pd hexagonal nanoplates are twin crystals, and composed of the top and bottom faces enclosed by the {111} planes with stacking faults and the side surfaces bound by mixed six {111} and six {100} planes. The Pd hexagonal nanoplates with well-defined and tunable longitudinal localized surface plasmon resonance (LSPR) have enabled the direct harvesting of visible to near-infrared light for catalytic cross coupling reactions. Upon plasmon excitation, the catalytic Suzuki coupling reactions of iodobenzene and phenylboronic acid accelerate by a plasmonic photocatalytic effect of plasmon induced hot electrons. The turnover frequency (TOF) of the Pd hexagonal nanoplates in a reaction illuminated with a λ = 300-1000 nm Xenon lamp at 176 mW cm-2 was 2.5 and 2.7 times higher than that of non-plasmonic {111}-enclosed Pd nanooctahedra and {100}-enclosed Pd nanocubes, respectively, and 1.7 times higher than the TOF obtained when the reaction was thermally heated to the same temperature.Photocatalytic conversion of solar energy to chemical energy is an efficient process in green chemistry because it facilitates room temperature chemical transformations by generating electronically excited states in photocatalysts. We report here on the robust synthesis, detailed structural characterization, and especially photocatalytic properties of plasmonic Pd hexagonal nanoplates for chemical reactions. The Pd hexagonal nanoplates are twin crystals, and composed of the top and bottom faces enclosed by the {111} planes with stacking faults and the side surfaces bound by mixed six {111

  18. The Blue Bottle Reaction as a General Chemistry Experiment on Reaction Mechanisms

    Science.gov (United States)

    Engerer, Steven C.; Cook, A. Gilbert

    1999-11-01

    A kinetics/reaction mechanism experiment using the classic blue bottle reaction is described. Using the scientific method (observe, question, hypothesize, experiment, repeat) students propose and test possible reaction mechanisms for the methylene blue-catalyzed oxidation of dextrose with its dramatic color change. Students are led to discover the three-step mechanism through a series of questions. An advanced version for honors lab courses is also suggested.

  19. A Study on the Kinetics of the Catalytic Reforming Reaction of CH4 with CO2: Determination of the Reaction Order

    Institute of Scientific and Technical Information of China (English)

    Chunyang Ji; Lihong Gong; Jiawei Zhang; Keying Shi

    2003-01-01

    The kinetics of the catalytic reforming reaction of methane with carbon dioxide to produce synthesis gas on a Ni/α-Al2O3 and a HSD-2 type commercial catalyst has been studied. The results indicate that the reaction orders are one and zero for methane and carbon dioxide, respectively, when the carbon dioxide partial pressure was about 12.5-30.0 kPa and the temperature was at 1123-1173 K. However,when the carbon dioxide partial pressure was changed to 30.0-45.0 kPa under the same temperature range of 1123 1173 K, the reaction orders of methane and carbon dioxide are one. Furthermore, average rate constants at different temperatures were determined.

  20. 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.

  1. Chemical reactions at the graphitic step-edge: changes in product distribution of catalytic reactions as a tool to explore the environment within carbon nanoreactors

    Science.gov (United States)

    Lebedeva, Maria A.; Chamberlain, Thomas W.; Thomas, Alice; Thomas, Bradley E.; Stoppiello, Craig T.; Volkova, Evgeniya; Suyetin, Mikhail; Khlobystov, Andrei N.

    2016-06-01

    A series of explorative cross-coupling reactions have been developed to investigate the local nanoscale environment around catalytically active Pd(ii)complexes encapsulated within hollow graphitised nanofibers (GNF). Two new fullerene-containing and fullerene-free Pd(ii)Salen catalysts have been synthesised, and their activity and selectivity towards different substrates has been explored in nanoreactors. The catalysts not only show a significant increase in activity and stability upon heterogenisation at the graphitic step-edges inside the GNF channel, but also exhibit a change in selectivity affected by the confinement which alters the distribution of isomeric products of the reaction. Furthermore, the observed selectivity changes reveal unprecedented details regarding the location and orientation of the catalyst molecules inside the GNF nanoreactor, inaccessible by any spectroscopic or microscopic techniques, thus shedding light on the precise reaction environment inside the molecular catalyst-GNF nanoreactor.A series of explorative cross-coupling reactions have been developed to investigate the local nanoscale environment around catalytically active Pd(ii)complexes encapsulated within hollow graphitised nanofibers (GNF). Two new fullerene-containing and fullerene-free Pd(ii)Salen catalysts have been synthesised, and their activity and selectivity towards different substrates has been explored in nanoreactors. The catalysts not only show a significant increase in activity and stability upon heterogenisation at the graphitic step-edges inside the GNF channel, but also exhibit a change in selectivity affected by the confinement which alters the distribution of isomeric products of the reaction. Furthermore, the observed selectivity changes reveal unprecedented details regarding the location and orientation of the catalyst molecules inside the GNF nanoreactor, inaccessible by any spectroscopic or microscopic techniques, thus shedding light on the precise reaction

  2. Basic research for nuclear energy : a study on photo-catalytic decomposition reactions of organics dissolved in water

    International Nuclear Information System (INIS)

    In an experiment on TiO2 photo-catalysis of five nitrogen-containing organic compounds, the changes of pH and total carbon contents were measured, and the dependence of their photo-catalytic characteristic upon their chemical structures were investigated. -- calculation of the effect of ionic carbon species in an aqueous solution on thermodynamic equilibrium, pH and conductivity showed a small quantity of organics could lead conductivity increase and pH reduction. -- Based on the results of photo-catalytic experiment of ethylamine, phenylhydrazine, pyridine, urea or EDTA, irradiated for 180 minutes after adsorption onto titanium dioxide for 60 minutes, relationship between nitrogen atomic charge and the first-order rate constant was as the following: R (1st - order rate constant) = δ (ε - a )1/3 + b where, ε : atomic charge of nitrogen in a molecular, δ, a and b : corrective coefficients

  3. Key nuclear reaction experiments discoveries and consequences

    CERN Document Server

    Paetz gen. Schieck, Hans

    2015-01-01

    In this book the author charts the developments in nuclear physics since its inception around a century ago by reviewing the key experiments that helped drive and shape our understanding of the field, especially in the context of the wider developments in physics in the early 20th Century. In addition to providing a path through the field and the crucial events it looks at how these experiments not only answered key questions at the time but presented new challenges to the contemporary perception of the nuclear and sub-atomic worlds and how they helped develop our present understanding of nuclear physics.

  4. Nuclear reaction modeling, verification experiments, and applications

    Energy Technology Data Exchange (ETDEWEB)

    Dietrich, F.S.

    1995-10-01

    This presentation summarized the recent accomplishments and future promise of the neutron nuclear physics program at the Manuel Lujan Jr. Neutron Scatter Center (MLNSC) and the Weapons Neutron Research (WNR) facility. The unique capabilities of the spallation sources enable a broad range of experiments in weapons-related physics, basic science, nuclear technology, industrial applications, and medical physics.

  5. 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.

  6. 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

  7. 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.

  8. Combinatorial development of solid catalytic materials design of high-throughput experiments, data analysis, data mining

    CERN Document Server

    Baerns, Manfred

    2009-01-01

    The book provides a comprehensive treatment of combinatorial development of heterogeneous catalysts. In particular, two computer-aided approaches that have played a key role in combinatorial catalysis and high-throughput experimentation during the last decade - evolutionary optimization and artificial neural networks - are described. The book is unique in that it describes evolutionary optimization in a broader context of methods of searching for optimal catalytic materials, including statistical design of experiments, as well as presents neural networks in a broader context of data analysis.

  9. Catalytic Reaction of Aryldiazoacetates with Indole and Its Derivatives: Profound Effect of N-1 Substitutent on the Reaction Pathways

    Institute of Scientific and Technical Information of China (English)

    ZHANG Xue-Jing; LIU Sheng-Ping; YAN Ming

    2008-01-01

    The reaction of indole and its derivatives with aryldiazoacetates has been studied in the presence of copper and The electron-donating group favored the formation of the β-alkylation products, while the electron-withdrawing group favored the formation of the cyclopropane products. A reaction mechanism was proposed based on the experimental data and previous research results. The structure of aryl group in diazo compounds also affected the yield of the β-alkylation products or the cyclopropane products.

  10. Synthesis of 1-alkyl triazolium triflate room temperature ionic liquids and their catalytic studies in multi-component Biginelli reaction

    Indian Academy of Sciences (India)

    Sankaranarayanan Nagarajan; Tanveer M Shaikh; Elango Kandasamy

    2015-09-01

    Synthesis of three Brønsted acid-based ionic liquids, namely, 1-ethyl-1,2,4-triazolium triflate (1a), 1-propyl-1,2,4-triazolium triflate (1b) and 1-butyl-1,2,4-triazolium triflate (1c), is described. These ionic liquids have been employed as catalysts for convenient and high-yielding one-pot synthesis of 3,4-dihydropyrimidin-2(1H)-ones and 3,4-dihydropyrimidin-2(1H)-thiones, which are Biginelli reaction products. Advantages of the methodology are operational convenience, short reaction times, avoidance of chromatographic purification and non-production of toxic waste. Further, the catalysts are easily recovered and reused without any noticeable diminution in their catalytic activity.

  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. Resonance Scattering Spectral Determination of Trace Penicillin G Using Immunonanogold-HauCI4-NH2OH Catalytic Reaction

    Institute of Scientific and Technical Information of China (English)

    WEN, Guiqing; LI, Yan; LIANG, Aihui; JIANG, Zhiliang

    2009-01-01

    Both nanogold and immunonanogold exhibit catalytic effect on the slow reaction of HAuCl4-NH2OH to form gold particles which displayed a resonance scattering (RS) peak at 580 nm. Using hapten penicillin G (PG) as a model, the nanogold in size of 9 nm was used to label rabbit anti-penicillin G antisera (RAPG) to obtain an immu- nonanogold probe (AuRAPG) for PG. The PG was combined with AuRAPG to form the immunocomplex and big- ger nanogold clusters. After centrifugation, the excess AuRAPG in the supematant exhibited catalytic effect on the reaction of HAuCl4-NH2OH, and the RS intensity at 580 nm (I580 nm) was enhanced greatly. With the addition of PG, the I580 nm decreased accordingly. Under the optimal conditions, the decreased intensity ΔI580 nm was proportional to the PG concentration in the range of 0.15-225 ng/mL, with a detection limit of 0.05 ng/mL for PG.

  13. NO-CO catalytic reaction on a square lattice: the effect of the Eley-Rideal mechanism

    International Nuclear Information System (INIS)

    Monte Carlo simulations have been used to explore the effects of the Eley-Rideal mechanism (reaction of CO molecule with already chemisorbed oxygen atom to produce CO2) on a simple Langmuir-Hinshelwood model for the NO-CO catalytic reaction on a square surface. The diffusion of the CO and N atoms on the surface and desorption of CO from the surface are also introduced into the model. Without diffusion and desorption, the model generates a very small reactive window of the order of 0.033. The moment CO partial pressure (yCO) departs from zero, continuous production of CO2 and N2 starts. A first-order transition terminates the catalytic activity at yCOyCO= 0.033 and the surface is poisoned with a combination of CO and N. However, the diffusion of the N atom and CO molecule shifts the transition point from 0.033 to higher values of yCO. The introduction of desorption of CO shows some interesting results. A very small desorption probability of CO (=0.01) increases the width of the reactive window to 0.12. However, this reactive window is separated by two transition points y1(∼0.2) and y2(∼0.32). For yCO1 (yCO>y2) the surface is poisoned by a combination of O and N (CO and N). With further increase in desorption probability the width increases significantly. (author)

  14. Recent developments in the production of liquid fuels via catalytic conversion of microalgae: experiments and simulations

    Energy Technology Data Exchange (ETDEWEB)

    Shi,Fan; Wang, Pin; Duan, Yuhua; Link, Dirk; Morreale, Bryan

    2012-01-01

    Due to continuing high demand, depletion of non-renewable resources and increasing concerns about climate change, the use of fossil fuel-derived transportation fuels faces relentless challenges both from a world markets and an environmental perspective. The production of renewable transportation fuel from microalgae continues to attract much attention because of its potential for fast growth rates, high oil content, ability to grow in unconventional scenarios, and inherent carbon neutrality. Moreover, the use of microalgae would minimize ‘‘food versus fuel’’ concerns associated with several biomass strategies, as microalgae do not compete with food crops in the food chain. This paper reviews the progress of recent research on the production of transportation fuels via homogeneous and heterogeneous catalytic conversions of microalgae. This review also describes the development of tools that may allow for a more fundamental understanding of catalyst selection and conversion processes using computational modelling. The catalytic conversion reaction pathways that have been investigated are fully discussed based on both experimental and theoretical approaches. Finally, this work makes several projections for the potential of various thermocatalytic pathways to produce alternative transportation fuels from algae, and identifies key areas where the authors feel that computational modelling should be directed to elucidate key information to optimize the process.

  15. Recent Developments on the Production of Transportation Fuels via Catalytic Conversion of Microalgae: Experiments and Simulations

    Energy Technology Data Exchange (ETDEWEB)

    Shi, Fan; Wang, Ping; Duan, Yuhua; Link, Dirk; Morreale, Bryan

    2012-08-02

    Due to continuing high demand, depletion of non-renewable resources and increasing concerns about climate change, the use of fossil fuel-derived transportation fuels faces relentless challenges both from a world markets and an environmental perspective. The production of renewable transportation fuel from microalgae continues to attract much attention because of its potential for fast growth rates, high oil content, ability to grow in unconventional scenarios, and inherent carbon neutrality. Moreover, the use of microalgae would minimize “food versus fuel” concerns associated with several biomass strategies, as microalgae do not compete with food crops in the food chain. This paper reviews the progress of recent research on the production of transportation fuels via homogeneous and heterogeneous catalytic conversions of microalgae. This review also describes the development of tools that may allow for a more fundamental understanding of catalyst selection and conversion processes using computational modelling. The catalytic conversion reaction pathways that have been investigated are fully discussed based on both experimental and theoretical approaches. Finally, this work makes several projections for the potential of various thermocatalytic pathways to produce alternative transportation fuels from algae, and identifies key areas where the authors feel that computational modelling should be directed to elucidate key information to optimize the process.

  16. A Laboratory Experiment on the Statistical Theory of Nuclear Reactions

    Science.gov (United States)

    Loveland, Walter

    1971-01-01

    Describes an undergraduate laboratory experiment on the statistical theory of nuclear reactions. The experiment involves measuring the relative cross sections for formation of a nucleus in its meta stable excited state and its ground state by applying gamma-ray spectroscopy to an irradiated sample. Involves 3-4 hours of laboratory time plus…

  17. Oxidation of Borneol to Camphor Using Oxone and Catalytic Sodium Chloride: A Green Experiment for the Undergraduate Organic Chemistry Laboratory

    Science.gov (United States)

    Lang, Patrick T.; Harned, Andrew M.; Wissinger, Jane E.

    2011-01-01

    A new green oxidation procedure was developed for the undergraduate organic teaching laboratories using Oxone and a catalytic quantity of sodium chloride for the conversion of borneol to camphor. This simple 1 h, room temperature reaction afforded high quality and yield of product, was environmentally friendly, and produced negligible quantities…

  18. Aluminosilicates as controlled molecular environments for selective photochemical and catalytic reactions

    International Nuclear Information System (INIS)

    This dissertation concerns research that involves photochemical, catalytic and spectroscopic studies of clays, pillared clays and zeolites. Incorporation of uranyl ions into hectorite, montmorillonite, bentonite and vermiculite clays was monitored by XRD and luminescence methods. Excitation and emission characteristics were studied in order to understand the behavior of uranyl ions in clays after various thermal treatments. Luminescence lifetime measurements elucidated the number of uranyl sites. Uranyl-exchanged clays were found to absorb light at lower energies (445-455nm) than analogous uranyl-exchanged zeolites (425nm). Each uranyl-exchanged clay was tested as a catalyst for the photoassisted oxidation of isopropyl alcohol. Energy transfer (ET) between uranyl and Eu(III) ions in different zeolite framework systems was examined. The efficiency of ET (eta/sub t/) was found to be affected by the type of framework present. Pillared bentonites were examined in the hydrocracking of decane. A catalytically and spectroscopically active dopant ion, Cr(III), was introduced into the clays in both pillared and unpillared forms depending upon synthetic conditions. EPR and DRS were employed to monitor the environment of Cr(III) for determination of its location - whether in the micropore structure or associated with alumina pillars. Catalytic behavior based upon this variability of location was examined. Incorporation of Cr(III) ions into an alumina pillar was found to increase the stability and activity with respect to an alumina PILC catalyst. The results of these studies suggest that selective, efficient catalysts can be designed around inorganic ions in aluminosilicate supports

  19. Aluminosilicates as controlled molecular environments for selective photochemical and catalytic reactions

    Energy Technology Data Exchange (ETDEWEB)

    Carrado, K.A.

    1986-01-01

    This dissertation concerns research that involves photochemical, catalytic and spectroscopic studies of clays, pillared clays and zeolites. Incorporation of uranyl ions into hectorite, montmorillonite, bentonite and vermiculite clays was monitored by XRD and luminescence methods. Excitation and emission characteristics were studied in order to understand the behavior of uranyl ions in clays after various thermal treatments. Luminescence lifetime measurements elucidated the number of uranyl sites. Uranyl-exchanged clays were found to absorb light at lower energies (445-455nm) than analogous uranyl-exchanged zeolites (425nm). Each uranyl-exchanged clay was tested as a catalyst for the photoassisted oxidation of isopropyl alcohol. Energy transfer (ET) between uranyl and Eu(III) ions in different zeolite framework systems was examined. The efficiency of ET (eta/sub t/) was found to be affected by the type of framework present. Pillared bentonites were examined in the hydrocracking of decane. A catalytically and spectroscopically active dopant ion, Cr(III), was introduced into the clays in both pillared and unpillared forms depending upon synthetic conditions. EPR and DRS were employed to monitor the environment of Cr(III) for determination of its location - whether in the micropore structure or associated with alumina pillars. Catalytic behavior based upon this variability of location was examined. Incorporation of Cr(III) ions into an alumina pillar was found to increase the stability and activity with respect to an alumina PILC catalyst. The results of these studies suggest that selective, efficient catalysts can be designed around inorganic ions in aluminosilicate supports.

  20. 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

  1. Pozzolanic Reaction Rate of Fluid Catalytic Cracking Residue (FC3R) in Cement Pastes

    OpenAIRE

    Paya Bernabeu, Jorge Juan; Monzó Balbuena, José Mª; Borrachero Rosado, María Victoria; SERGIO VELAZQUEZ RODRIGUEZ

    2013-01-01

    Fluid catalytic cracking catalyst residue (FC3R) is a waste material generated in the petroleum industry. Previous research has shown that FC3R exhibits excellent pozzolanic properties in Portland cement mixtures. The pozzolanic activity of FC3R was studied by means of thermogravimetric analysis (measurement of lime fixation) and cold hydrochloric acid treatment (quantification of FC3R reacted). A water/binder ratio of 0.40 was used in the study in the preparation of a control paste (without ...

  2. Possible nature of the catalytic activity of metalloporphyrins in reactions to nonchain oxidation of olefins

    Energy Technology Data Exchange (ETDEWEB)

    Solov' eva, A.B.; Karakozova, E.I.; Karmilova, L.V.; Timashev, S.F.

    1985-05-01

    The authors hypothesize that an intermediate cyclic complex, TPPMn(II) with oxygen and the olefin, is formed during the catalytic oxidation of olefins with a varying degree of substitution in the double bond of the system: molecular oxygen-TPP MnCl-NaBH/sub 4/ (TPP: tetraphenylporphyrin). They hypothesize that strong electrical fields in the submicrovicinity of the metalloporphyrin (MP) molecule favor the formation of a cyclic intermediate complex. They conclude that the possibility of the formation of a cyclic intermediate complex is verified on the basis of data on the state of the central reduced ion and the type of coordination of the oxygen molecule.

  3. Reaction phenomena of catalytic partial oxidation of methane under the impact of carbon dioxide addition and heat recirculation

    International Nuclear Information System (INIS)

    The reaction phenomena of CPOM (catalytic partial oxidation of methane) in a Swiss-roll reactor are studied numerically where a rhodium-based catalyst bed is embedded at the center of the reactor. CO2 is added into the feed gas and excess enthalpy recovery is performed to evaluate their influences on CPOM performance. In the study, the mole ratio of O2 to CH4 (O2/CH4 ratio) is fixed at 0.5 and the mole ratio of CO2 to O2 (CO2/O2 ratio) is in the range of 0–2. The results reveal that CO2 addition into the influent has a slight effect on methane combustion, but significantly enhances dry reforming and suppresses steam reforming. The reaction extents of steam reforming and dry reforming in CPOM without heat recovery and CO2 addition are in a comparable state. Once CO2 is added into the feed gas, the dry reforming is enhanced, thereby dominating CH4 consumption. Compared to the reactor without excess enthalpy recovery, heat recirculation drastically increases the maximum reaction temperature and CH4 conversion in the catalyst bed; it also intensifies the H2 selectivity, H2 yield, CO2 conversion, and syngas production rate. The predictions indicate that the heat recirculation is able to improve the syngas formation up to 45%. - Highlights: • Catalytic partial oxidation of methane with CO2 addition and heat recovery is studied. • CO2 addition has a slight effect on methane combustion. • CO2 addition significantly enhances dry reforming and suppresses steam reforming. • Dry reforming dominates CH4 consumption when CO2 addition is large. • Heat recirculation can improve the syngas formation up to 45%

  4. Synthesis of α-Amidoketones from Vinyl Esters via a Catalytic/Thermal Cascade Reaction.

    Science.gov (United States)

    Holthusen, Katharina; Leitner, Walter; Franciò, Giancarlo

    2016-06-01

    A straightforward, modular, and atom-efficient method is reported for the synthesis of α-amidoketones from vinyl esters via a cascade reaction including hydroformylation, condensation with a primary amine, and a rearrangement step giving water as the only byproduct. The reaction sequence can be performed in one pot or as a three-step procedure. The synthetic applicability is demonstrated by the preparation of different α-amidoketones in moderate to good yields. PMID:27196947

  5. One-pot Solvent-free Catalytic Dimerization Reaction of Phenylacetylene to 1-Phenylnaphthalene

    Indian Academy of Sciences (India)

    Avat (Arman) Taherpour; Sepehr Taban; Ako Yari

    2015-09-01

    In this study, we report a smooth one-pot, solvent-free catalytic dimerization of phenylacetylene (1) to 1-phenylnaphthalene (2) by Cu/C at room temperature in good yield (∼100%). In the computational study, the structure of the 1-phenylnaphthalene was optimized by DFT-B3LYP/6-31G* method. The rotation barrier around C-C of the phenyl and naphthalene parts of the molecule and its UV-Visible spectrum were calculated. The modelling of the mechanism of production of 2 from 1 was performed with and without Cu/C catalyst. The data of EDS and SEM of the Cu/C catalyst surface are also reported.

  6. Pyrolysis-GCMS Analysis of Solid Organic Products from Catalytic Fischer-Tropsch Synthesis Experiments

    Science.gov (United States)

    Locke, Darren R.; Yazzie, Cyriah A.; Burton, Aaron S.; Niles, Paul B.; Johnson, Natasha M.

    2015-01-01

    Abiotic synthesis of complex organic compounds in the early solar nebula that formed our solar system is hypothesized to occur via a Fischer-Tropsch type (FTT) synthesis involving the reaction of hydrogen and carbon monoxide gases over metal and metal oxide catalysts. In general, at low temperatures (less than 200 C), FTT synthesis is expected to form abundant alkane compounds while at higher temperatures (greater than 200 C) it is expected to product lesser amounts of n-alkanes and greater amounts of alkene, alcohol, and polycyclic aromatic hydrocarbons (PAHs). Experiments utilizing a closed-gas circulation system to study the effects of FTT reaction temperature, catalysts, and number of experimental cycles on the resulting solid insoluble organic products are being performed in the laboratory at NASA Goddard Space Flight Center. These experiments aim to determine whether or not FTT reactions on grain surfaces in the protosolar nebula could be the source of the insoluble organic matter observed in meteorites. The resulting solid organic products are being analyzed at NASA Johnson Space Center by pyrolysis gas chromatography mass spectrometry (PY-GCMS). PY-GCMS yields the types and distribution of organic compounds released from the insoluble organic matter generated from the FTT reactions. Previously, exploratory work utilizing PY-GCMS to characterize the deposited organic materials from these reactions has been reported. Presented here are new organic analyses using magnetite catalyst to produce solid insoluble organic FTT products with varying reaction temperatures and number of experimental cycles.

  7. Catalytic control of diesel engine particulate emission: studies on model reactions over a EURO Pt-1 (Pt/SiO2) catalyst

    OpenAIRE

    Xue, E.; Seshan, K.; Ommen, van, B.; Ross, J.R.H.

    1993-01-01

    The catalytic oxidation of nitric oxide to nitrogen dioxide in the presence of sulphur dioxide over a standard Pt/SiO2 catalyst (EuroPt-1) was studied. The gas-phase reactions between nitric oxide, sulphur dioxide and oxygen were found to be insignificant under the experimental conditions concerned. The Pt/SiO2 catalyst was observed to be very active in catalyzing the reactions both of NO + O2 to NO2 and of SO2 + O2 to SO3. In the presence of sulphur dioxide, the catalytic activity for nitric...

  8. Hexene catalytic cracking over 30% sapo-34 catalyst for propylene maximization: influence of reaction conditions and reaction pathway exploration

    Directory of Open Access Journals (Sweden)

    Z. Nawaz

    2009-12-01

    Full Text Available Higher olefins are produced as a by product in a number of refinery processes and are one of the potential raw materials to produce propylene. In the present study, FCC model feed compound was considered to explore the olefin cracking features and options to enhance propylene using 30% SAPO-34 zeolite as catalyst in a micro-reactor. The superior selectivity of propylene (73 wt% and higher total olefin selectivity was obtained over 30% SAPO-34 catalyst than over Y or ZSM-5 zeolite catalysts. The thermodynamical constraints were found to be relatively less serious in the case of 1-hexene conversion. Most of the 1-hexene follows a direct cracking pathway to give two propylene molecules, due to weak acid sites and better diffusion opportunities. The higher temperature and short residence time could also suppress the hydrogen transfer reactions. From OPE (olefins performance envelop the products were classified as primary, secondary, or both. Iso-hexene (2-methyl-2-pentene cracking was also analyzed in order to justify a shape selective effect of the SAPO-34 catalyst. A detailed integrated reaction network together with an associated mechanism was proposed and discussed in detail for their fundamental importance in understanding the olefin cracking processes over SAPO-34.

  9. The effect of external magnetic fields on the catalytic activity of Pd nanoparticles in Suzuki cross-coupling reactions

    Science.gov (United States)

    Gao, Lei; Wang, Changlai; Li, Ren; Li, Ran; Chen, Qianwang

    2016-04-01

    Pd nanoparticles supported on Co3[Co(CN)6]2 nanoparticles (marked as Pd@Co3[Co(CN)6]2 nanoparticles) were prepared as catalysts for the Suzuki cross-coupling reaction under external magnetic fields (MFs). It is shown that a weak external MF can increase the rate of the Suzuki cross-coupling reaction at room temperature, and with the increase of the strength of external MFs the reaction rate also increased. At 30 °C, the yield was increased by nearly 50% under a 0.5 T external MF after 24 hours compared to that without a MF applied. Theoretical calculations revealed that the adsorption energy changed from -1.07 to -1.12 eV in the presence of MFs, which increased by 5% compared with the absence of MFs, leading to a lower total energy of the adsorption system, which is beneficial to the reaction. From the analysis of the partial density states, it could be seen that the 2p orbital of the carbon atom in bromobenzene and the 4d orbital of the Pd atom overlap more closely in the presence of MFs, which is beneficial for the electron transfer from the Pd substrate to the bromobenzene molecule. This study is helpful in understanding the interaction between MFs and catalysts and regulating the process of catalytic reactions via MFs.Pd nanoparticles supported on Co3[Co(CN)6]2 nanoparticles (marked as Pd@Co3[Co(CN)6]2 nanoparticles) were prepared as catalysts for the Suzuki cross-coupling reaction under external magnetic fields (MFs). It is shown that a weak external MF can increase the rate of the Suzuki cross-coupling reaction at room temperature, and with the increase of the strength of external MFs the reaction rate also increased. At 30 °C, the yield was increased by nearly 50% under a 0.5 T external MF after 24 hours compared to that without a MF applied. Theoretical calculations revealed that the adsorption energy changed from -1.07 to -1.12 eV in the presence of MFs, which increased by 5% compared with the absence of MFs, leading to a lower total energy of the

  10. Insight into the Catalytic Mechanism of Bimetallic Platinum–Copper Core–Shell Nanostructures for Nonaqueous Oxygen Evolution Reactions

    Energy Technology Data Exchange (ETDEWEB)

    Ma, Lu; Luo, Xiangyi; Kropf, A. Jeremy; Wen, Jianguo; Wang, Xiaoping; Lee, Sungsik; Myers, Deborah J.; Miller, Dean; Wu, Tianpin; Lu, Jun; Amine, Khalil

    2016-01-01

    The oxygen evolution reaction (OER) plays a critical role in multiple energy conversion and storage applications. However, its sluggish kinetics usually results in large voltage polarization and unnecessary energy loss. Therefore, designing efficient catalysts that could facilitate this process has become an emerging topic. Here, we present a unique Pt–Cu core–shell nanostructure for catalyzing the nonaqueous OER. The catalysts were systematically investigated with comprehensive spectroscopic techniques, and applied in nonaqueous Li–O2 electrochemical cells, which exhibited dramatically reduced charging overpotential (<0.2 V). The superior performance is explained by the robust Cu(I) surface sites stabilized by the Pt core in the nanostructure. The insights into the catalytic mechanism of the unique Pt–Cu core–shell nanostructure gained in this work are expected to serve as a guide for future design of other nanostructured bimetallic OER catalysts.

  11. Spectrophotometric reaction rate method for the determination of osmium by its catalytic effect on the oxidation of gallocyanine by bromate.

    Science.gov (United States)

    Ensafi, A A; Shamss-E-Sollari, E

    1994-10-01

    A simple kinetic spectrophotometric method was developed for the determination of osmium. The method is based on the catalytic effect of osmium as osmium tetroxide on the oxidation of gallocyanine by bromate at pH 7. The reaction is monitored spectrophotometrically by measuring the decreasing absorbance of gallocyanine at 620 nm by the fixed-time method. A detection limit of 0.01 ng/ml and linear calibration curve from 0.1 to 100 and from 100 to 1200 ng/ml Os(VIII) is reported. The relative standard deviation for 0.0100 microg/ml Os(VIII) is 0.8% (N = 10). The method is free from most interferences. Osmium in synthetic samples is determined by this method, with satisfactory results. PMID:18966116

  12. Investigation of catalytic activity towards oxygen reduction reaction of Pt dispersed on boron doped graphene in acid medium.

    Science.gov (United States)

    Pullamsetty, Ashok; Sundara, Ramaprabhu

    2016-10-01

    Boron doped graphene was prepared by a facile method and platinum (Pt) decoration over boron doped graphene was done in various chemical reduction methods such as sodium borohydride (NaBH4), polyol and modified polyol. X-ray diffraction analysis indicates that the synthesized catalyst particles are present in a nanocrystalline structure and transmission and scanning electron microscopy were employed to investigate the morphology and particle distribution. The electrochemical properties were investigated with the help of the rotating disk electrode (RDE) technique and cyclic voltammetry. The results show that the oxygen reduction reaction (ORR) takes place by a four-electron process. The kinetics of the ORR was evaluated using K-L and Tafel plots. The electrocatalyst obtained in modified polyol reduction method has shown the better catalytic activity compared to other two electrocatalysts. PMID:27393888

  13. Synthesis, characterization, and catalytic activity in Suzuki coupling and catalase-like reactions of new chitosan supported Pd catalyst.

    Science.gov (United States)

    Baran, Talat; Inanan, Tülden; Menteş, Ayfer

    2016-07-10

    The aim of this study is to analyze the synthesis of a new chitosan supported Pd catalyst and examination of its catalytic activity in: Pd catalyst was synthesized using chitosan as a biomaterial and characterized with FTIR, TG/DTG, XRD, (1)H NMR, (13)C NMR, SEM-EDAX, ICP-OES, Uv-vis spectroscopies, and magnetic moment, along with molar conductivity analysis. Biomaterial supported Pd catalyst indicated high activity and long life time as well as excellent turnover number (TON) and turnover frequency (TOF) values in Suzuki reaction. Biomaterial supported Pd catalyst catalyzed H2O2 decomposition reaction with considerable high activity using comparatively small loading catalyst (10mg). Redox potential of biomaterial supported Pd catalyst was still high without negligible loss (13% decrease) after 10 cycles in reusability tests. As a consequence, eco-friendly biomaterial supported Pd catalyst has superior properties such as high thermal stability, long life time, easy removal from reaction mixture and durability to air, moisture and high temperature. PMID:27106147

  14. Synthesis of high purity single-walled carbon nanotubes from ethanol by catalytic gas flow CVD reactions

    International Nuclear Information System (INIS)

    Highly pure single-walled carbon nanotubes (SWNTs) with their contents >96% of the total products were achieved by chemical vapour deposition gas flow reactions using ethanol as the carbon source. The high purity SWNTs were formed under critically controlled synthesis conditions and by applying a high hydrogen flow, under which the non-catalytic condensation of carbon was completely suppressed. Purification of the products in acid at ambient conditions readily yielded over 99% pure SWNT products, as the only impurities left in the products were iron particles of clean surface. Therefore, the present study demonstrates the full potential of the CVD gas flow reactions in continuous production of high quality SWNTs. Comparable syntheses were conducted using other alcohols in place of ethanol and it was found that high alkyl alcohols like isopropanol and hexanol produced more amorphous carbon while methanol produced no carbon. The high yield growth of SWNTs was attributed greatly to the reaction chemistry of ethanol and the 'right' amount of hydrogen in the system, as discussed

  15. The effect of noble metals on catalytic methanation reaction over supported Mn/Ni oxide based catalysts

    Directory of Open Access Journals (Sweden)

    Wan Azelee Wan Abu Bakar

    2015-09-01

    Full Text Available Carbon dioxide (CO2 in sour natural gas can be removed using green technology via catalytic methanation reaction by converting CO2 to methane (CH4 gas. Using waste to wealth concept, production of CH4 would increase as well as creating environmental friendly approach for the purification of natural gas. In this research, a series of alumina supported manganese–nickel oxide based catalysts doped with noble metals such as ruthenium and palladium were prepared by wetness impregnation method. The prepared catalysts were run catalytic screening process using in-house built micro reactor coupled with Fourier Transform Infra Red (FTIR spectroscopy to study the percentage CO2 conversion and CH4 formation analyzed by GC. Ru/Mn/Ni(5:35:60/Al2O3 calcined at 1000 °C was found to be the potential catalyst which gave 99.74% of CO2 conversion and 72.36% of CH4 formation at 400 °C reaction temperature. XRD diffractogram illustrated that the supported catalyst was in polycrystalline with some amorphous state at 1000 °C calcination temperature with the presence of NiO as active site. According to FESEM micrographs, both fresh and used catalysts displayed spherical shape with small particle sizes in agglomerated and aggregated mixture. Nitrogen Adsorption analysis revealed that both catalysts were in mesoporous structures with BET surface area in the range of 46–60 m2/g. All the impurities have been removed at 1000 °C calcination temperature as presented by FTIR, TGA–DTA and EDX data.

  16. Effect of size of copper nanoparticles on its catalytic behaviour in Ullman reaction

    Indian Academy of Sciences (India)

    Mohd Samim; N K Kaushik; Amarnath Maitra

    2007-10-01

    The condensation of iodobenzene to biphenyl is an industrially important reaction due to its significant role in organic synthesis as drug intermediates. The reaction takes place in the presence of copper powder as catalyst. We have shown in this paper that the size of the copper nanoparticles as well as its exposed surface area is responsible for the yield of chemical reaction. The uncapped copper powder showed a 43% conversion of iodobenzene to biphenyl in 5 h under our experimental conditions. Same amount of copper nanoparticles (size, ∼ 66 nm diameter) prepared by citrate capping showed 88% conversion of iodobenzene to biphenyl, which increased to about 95% when 8 nm diameter capped copper nanoparticles are used. Surprisingly, 5 nm size copper nanoparticles showed no change in the yield of about 95%.

  17. 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

  18. Carbon-13 and deuterium isotope effects on the catalytic reactions of biotin carboxylase

    International Nuclear Information System (INIS)

    13C and 2H kinetic isotope effects have been used to investigate the mechanism of enzymic biotin carboxylation. /sup D/(V/K) is 0.50 in 80% D2O at pD 8.0 for the forward reaction and 0.57 at pD 8.5 for the phosphorylation of ADP by carbamoyl phosphate. These values approach the theoretical maximum limit for a reaction in which a proton is transferred from a sulfhydryl to a nitrogen or oxygen base. Therefore, it appears that this portion of the reaction is at or near equilibrium. 13(V/K) at pH 8 is 1.007; the small magnitude of this number suggests that the reaction is almost fully committed by the time the carbon-sensitive steps are reached. There does not appear to be a reverse commitment to the reaction under the conditions in which 13(V/K) was determined. A large forward commitment is consistent with the failure to observe positional isotope exchange from the βγ-bridge position to the β-nonbridge position in [18O4]ATP or washout of 18O from the γ-nonbridge positions. Transfer of 18O from bicarbonate to inorganic phosphate in the forward reaction was clearly observed, however. These observations suggest that biotin carboxylase exists in two distinct forms which differ in the protonation states of the two active-site bases, one of which is a sulfhydryl. Only when the sulfhydryl is ionized and the second base protonated can catalysis take place. Carboxylation of biotin is postulated to occur via a pathway in which carboxyphosphate is formed by nucleophilic attack of bicarbonate on ATP. Decarboxylation of carboxyphosphate in the active site generates CO2, which serves to carboxylate the isourea tautomer of biotin that is generated by the removal of the proton on N1' by the ionized sulfhydryl

  19. Plasma-catalytic hybrid system using spouted bed with a gliding arc discharge: CH{sub 4} reforming as a model reaction

    Energy Technology Data Exchange (ETDEWEB)

    Lee, H; Sekiguchi, H, E-mail: lee.h.ac@m.titech.ac.jp [Department of Chemical Engineering, Tokyo Institute of Technology, 2-12-1 O-okayama, Meguro-ku, Tokyo 152-8552 (Japan)

    2011-07-13

    A combination of a gliding arc discharge and a spouted catalytic bed was used to investigate a plasma-catalytic hybrid system using CH{sub 4} reforming as a model reaction. Alumina-supported catalysts that contained 0.5 wt% of Pt, Pd, Rh, and Ru (denoted as Pt/Al{sub 2}O{sub 3}, Pd/Al{sub 2}O{sub 3}, Rh/Al{sub 2}O{sub 3} and Ru/Al{sub 2}O{sub 3}, respectively) were used. For comparison, active Al{sub 2}O{sub 3} particles were also examined. The conversion of CH{sub 4} and the selectivity of the product were investigated by changing the feed flow rate and reaction time. The production of C{sub 2}H{sub 2}, H{sub 2} and soot was observed in the gliding arc discharge without a catalyst. Using Pt/Al{sub 2}O{sub 3} and Pd/Al{sub 2}O{sub 3}with the gliding arc discharge, C{sub 2}H{sub 4}, C{sub 2}H{sub 6} and C{sub 2}H{sub 2} were produced. It is considered that C{sub 2}H{sub 4} and C{sub 2}H{sub 6} were formed by the hydrogenation of C{sub 2}H{sub 2} on the active site of Pt/Al{sub 2}O{sub 3} and Pd/Al{sub 2}O{sub 3}. A stronger resistance to deactivation was shown in the presence of Pd/Al{sub 2}O{sub 3} than in the presence of Pt/Al{sub 2}O{sub 3}, whereas the selectivity of hydrocarbon using Rh/Al{sub 2}O{sub 3} and Ru/Al{sub 2}O{sub 3} showed a tendency similar to that in active Al{sub 2}O{sub 3} and non-catalytic experiments. The proposed reactor has a potential to improve the selectivity of the plasma process.

  20. A New Type of Traveling Interface Modulations in a Catalytic Surface Reaction

    OpenAIRE

    Rafti, M.; Uecker, H.; Lovis, F.; Krupennikova, V.; Imbihl, R.

    2011-01-01

    A new type of traveling interface modulations has been observed in the NH$_3$ + O$_2$ reaction on a Rh(110) surface. A model is set up which reproduces the effect, which is attributed to diffusional mixing of two spatially separated adsorbates causing an excitability which is strictly localized to the vicinity of the interface of the adsorbate domains.

  1. Catalytic and DRIFTS study of the WGS reaction on Pt-based catalysts

    Energy Technology Data Exchange (ETDEWEB)

    Vignatti, Ch.; Avila, M.S.; Apesteguia, C.R.; Garetto, T.F. [Catalysis Science and Engineering Research Group (GICIC), Instituto de Investigaciones en Catalisis y Petroquimica - INCAPE - (UNL-CONICET), Santiago del Estero 2654, 3000 Santa Fe (Argentina)

    2010-07-15

    The water-gas shift (WGS) activity of Pt/SiO{sub 2}, Pt/CeO{sub 2} and Pt/TiO{sub 2} catalysts was studied by in-situ diffuse reflection infrared Fourier transform spectroscopy (DRIFTS). Samples contained a similar amount of Pt, between 0.34 and 0.50%, and were characterized by employing a variety of physical and spectroscopic techniques. The catalyst activities were evaluated through both CO conversion versus temperature and CO conversion versus time tests. The DRIFTS spectra were obtained on stream during the WGS reaction at increasing temperatures, from 303 to 573 K. Reduced ceria was the only active support and promoted the WGS reaction on surface bridging OH groups that react with CO to form formate intermediates. Pt/SiO{sub 2} was more active than CeO{sub 2} and catalyzed the WGS reaction through a monofunctional redox mechanism on metallic Pt sites. The CO conversion turnover rate was more than one order of magnitude greater on Pt/CeO{sub 2} than on Pt/SiO{sub 2} showing that the reaction proceeds faster via a bifunctional metal-support mechanism. Platinum on Pt/CeO{sub 2} increased the concentration of OH groups by increasing the ceria reduction extent and also provided a faster pathway for the formation of formate intermediates in comparison to CeO{sub 2} support. Pt/TiO{sub 2} catalysts were clearly more active than Pt/CeO{sub 2}. The WGS reaction on Pt/TiO{sub 2} was catalyzed via a bifunctional metal-support mechanism, probably involving the activation of CO and water on the metal and the support, respectively. The role of platinum on Pt/TiO{sub 2} was critical for promoting the reduction of Ti{sup 4+} ions to Ti{sup 3+} which creates oxygen vacancies in the support to efficiently activate water. (author)

  2. Structural studies of the catalytic reaction pathway of a hyperthermophilic histidinol-phosphate aminotransferase

    OpenAIRE

    Fernandez, F.J. (Francisco J.); Vega, M C; Lehmann, F; Sandmeier, E; Gehring, H; Christen, P; Wilmanns, M.

    2004-01-01

    In histidine biosynthesis, histidinol-phosphate aminotransferase catalyzes the transfer of the amino group from glutamate to imidazole acetol-phosphate producing 2-oxoglutarate and histidinol phosphate. In some organisms such as the hyperthermophile Thermotoga maritima, specific tyrosine and aromatic amino acid transaminases have not been identified to date, suggesting an additional role for histidinol-phosphate aminotransferase in other transamination reactions generating aromatic amino acid...

  3. Phosphinocyclodextrins as confining units for catalytic metal centres. Applications to carbon–carbon bond forming reactions

    OpenAIRE

    Matthieu Jouffroy; Rafael Gramage-Doria; David Sémeril; Dominique Armspach; Dominique Matt; Werner Oberhauser; Loïc Toupet

    2014-01-01

    The capacity of two cavity-shaped ligands, HUGPHOS-1 and HUGPHOS-2, to generate exclusively singly phosphorus-ligated complexes, in which the cyclodextrin cavity tightly wraps around the metal centre, was explored with a number of late transition metal cations. Both cyclodextrin-derived ligands were assessed in palladium-catalysed Mizoroki–Heck coupling reactions between aryl bromides and styrene on one hand, and the rhodium-catalysed asymmetric hydroformylation of styrene on the other hand. ...

  4. Catalytic performance of Metal-Organic-Frameworks vs.extra-large porezeolite UTL in condensation reactions

    Czech Academy of Sciences Publication Activity Database

    Shamzhy, Mariya; Opanasenko, Maksym; Shvets, O. V.; Čejka, Jiří

    2013-01-01

    Roč. 1, AUG 2013 (2013), s. 1-11. ISSN 2296-2646 R&D Projects: GA ČR GBP106/12/G015 Grant ostatní: European Commission(XE) FP7/2007-2013, contract 228862 Institutional support: RVO:61388955 Keywords : condensation reactions * MOFs * zeolites Subject RIV: CF - Physical ; Theoretical Chemistry http://www.frontiersin.org/Journal/10.3389/fchem.2013.00011/abstract

  5. Reproduction of a Protocell by Replication of Minority Molecule in Catalytic Reaction Network

    OpenAIRE

    Kamimura, Atsushi; Kaneko, Kunihiko

    2010-01-01

    For understanding the origin of life, it is essential to explain the development of a compartmentalized structure, which undergoes growth and division, from a set of chemical reactions. In this study, a hypercycle with two chemicals that mutually catalyze each other is considered in order to show that the reproduction of a protocell with a growth-division process naturally occurs when the replication speed of one chemical is considerably slower than that of the other chemical. It is observed ...

  6. Compartmentalization and Cell Division through Molecular Discreteness and Crowding in a Catalytic Reaction Network

    OpenAIRE

    Atsushi Kamimura; Kunihiko Kaneko

    2014-01-01

    Explanation of the emergence of primitive cellular structures from a set of chemical reactions is necessary to unveil the origin of life and to experimentally synthesize protocells. By simulating a cellular automaton model with a two-species hypercycle, we demonstrate the reproduction of a localized cluster; that is, a protocell with a growth-division process emerges when the replication and degradation speeds of one species are respectively slower than those of the other species, because of ...

  7. CO-H2-O2 reaction on a catalytic surface: A computer simulation study

    International Nuclear Information System (INIS)

    The oxidation of carbon monoxide to form carbon dioxide and the oxidation of hydrogen to form water are the reactions of environmental and industrial importance. These two reactions have been studied independently by Monte Carlo computer simulation using Langmuir-Hinshelwood mechanism but no effort has been made to study the combined CO-H2-O2 reaction on these lines. Keeping in view the importance of this 3-component system, the surface coverages and production rates are studied as a function of CO partial pressure for different ratios of H2 and O2. The diffusion of reacting species on the surface as well as their desorption from the surface is also introduced to include temperature effects. The phase diagrams of the system are drawn to observe the behavior of these atoms/molecules on the surface and the production of CO2 and H2O are determined at different concentrations of H2. The results are compared with 2-component systems.

  8. 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

  9. Site-specific growth of Au-Pd alloy horns on Au nanorods: a platform for highly sensitive monitoring of catalytic reactions by surface enhancement Raman spectroscopy.

    Science.gov (United States)

    Huang, Jianfeng; Zhu, Yihan; Lin, Ming; Wang, Qingxiao; Zhao, Lan; Yang, Yang; Yao, Ke Xin; Han, Yu

    2013-06-12

    Surface-enhanced Raman scattering (SERS) is a highly sensitive probe for molecular detection. The aim of this study was to develop an efficient platform for investigating the kinetics of catalytic reactions with SERS. To achieve this, we synthesized a novel Au-Pd bimetallic nanostructure (HIF-AuNR@AuPd) through site-specific epitaxial growth of Au-Pd alloy horns as catalytic sites at the ends of Au nanorods. Using high-resolution electron microscopy and tomography, we successfully reconstructed the complex three-dimensional morphology of HIF-AuNR@AuPd and identified that the horns are bound with high-index {11l} (0.25 facets. With an electron beam probe, we visualized the distribution of surface plasmon over the HIF-AuNR@AuPd nanorods, finding that strong longitudinal surface plasmon resonance concentrated at the rod ends. This unique crystal morphology led to the coupling of high catalytic activity with a strong SERS effect at the rod ends, making HIF-AuNR@AuPd an excellent bifunctional platform for in situ monitoring of surface catalytic reactions. Using the hydrogenation of 4-nitrothiophenol as a model reaction, we demonstrated that its first-order reaction kinetics could be accurately determined from this platform. Moreover, we clearly identified the superior catalytic activity of the rod ends relative to that of the rod bodies, owing to the different SERS activities at the two positions. In comparison with other reported Au-Pd bimetallic nanostructures, HIF-AuNR@AuPd offered both higher catalytic activity and greater detection sensitivity. PMID:23675958

  10. Site-specific growth of Au-Pd alloy horns on Au nanorods: A platform for highly sensitive monitoring of catalytic reactions by surface enhancement raman spectroscopy

    KAUST Repository

    Huang, Jianfeng

    2013-06-12

    Surface-enhanced Raman scattering (SERS) is a highly sensitive probe for molecular detection. The aim of this study was to develop an efficient platform for investigating the kinetics of catalytic reactions with SERS. To achieve this, we synthesized a novel Au-Pd bimetallic nanostructure (HIF-AuNR@AuPd) through site-specific epitaxial growth of Au-Pd alloy horns as catalytic sites at the ends of Au nanorods. Using high-resolution electron microscopy and tomography, we successfully reconstructed the complex three-dimensional morphology of HIF-AuNR@AuPd and identified that the horns are bound with high-index {11l} (0.25 < l < 0.43) facets. With an electron beam probe, we visualized the distribution of surface plasmon over the HIF-AuNR@AuPd nanorods, finding that strong longitudinal surface plasmon resonance concentrated at the rod ends. This unique crystal morphology led to the coupling of high catalytic activity with a strong SERS effect at the rod ends, making HIF-AuNR@AuPd an excellent bifunctional platform for in situ monitoring of surface catalytic reactions. Using the hydrogenation of 4-nitrothiophenol as a model reaction, we demonstrated that its first-order reaction kinetics could be accurately determined from this platform. Moreover, we clearly identified the superior catalytic activity of the rod ends relative to that of the rod bodies, owing to the different SERS activities at the two positions. In comparison with other reported Au-Pd bimetallic nanostructures, HIF-AuNR@AuPd offered both higher catalytic activity and greater detection sensitivity. © 2013 American Chemical Society.

  11. Catalytic dimerization of propene with a Bis(salicyladiminato)Nic le (II) catalyst using 2,4,6-trichlorophenol for isomerization reactions

    International Nuclear Information System (INIS)

    A bis(salicylaldiminato)nic le(II) catalyst was used for dimerization reactions of propene. The catalyst precursor was activated with a triethylaluminum/aluminum trichloride mixture in the presence of phosphines and 2, 4, 6-trichlorophenol. The influence of the various components on the catalytic activity and product distribution is shown.

  12. Structural and catalytic properties of a novel vanadium containing solid core mesoporous silica shell catalysts for gas phase oxidation reaction

    Indian Academy of Sciences (India)

    N Venkatathri; Vijayamohanan K Pillai; A Rajini; M Nooka Raju; I A K Reddy

    2013-01-01

    A novel vanadium containing solid core mesoporous silica shell catalyst was synthesized with different Si/V ratios by sol-gel method under neutral conditions. The synthesized materials were characterized by various techniques and gas phase diphenyl methane oxidation reaction. The mesoporosity combined with microporosity are formed by incorporation of octadecyltrichloro silane and triethylamine in the catalyst and it was found out from E-DAX and BET—surface area analysis. The material was found to be nanocrystalline. Vanadium is present as V4+ species in as-synthesized samples and convert to V5+ on calcination. Most of the vanadium is present in tetrahedral or square pyramidal environment. Incorporation of vanadium in silica framework was confirmed by 29Si MAS NMR analysis. Among the various vanadium containing solid core mesoporous silica shell catalysts, the Si/V =100 ratio exhibited maximum efficiency towards diphenyl methane to benzophenone gas phase reaction. The optimum condition required for maximum conversion and selectivity was found out from the catalytic studies.

  13. Spectrophotometric Determination of Trace Cyanide in Fruit Wines by the Catalytic Reaction of Ninhydrin Following Micro-Distillation

    Directory of Open Access Journals (Sweden)

    Saksit Chanthai

    2014-03-01

    Full Text Available Trace analysis of cyanide (CN based on the absorbance of the catalytic reaction of ninhydrin (NH in the presence of CN- was developed. This reaction was investigated consisting of 0.08 M NH, 0.4 M Na2CO3, 1% (v/v Tween 20 and 2.5 M NaOH in 5-mL final volume. The absorbance of the CN-NH complex was measured against the reagent blank at 598 nm. The calibration curve was widely linear over the range of 40-160 µg/L with r2 >0.99. The method recoveries of free cyanide, bound cyanide and total cyanide for wine samples were found in the range of 76.2-89.2%, 73.2-91.2% and 76.8-94.8%, respectively, at 250 µg/L CN- spiked level. Limit of detection was 6 µg/L. The reproducibility of the proposed method was less than 4.44%. This method was then applied for local Thai fruit wines. No trace amount of cyanide was detected, as if high recovery (88.4% of the micro-distillation was guaranteed. The obtained results were in agreement with those of the chloramine-T/barbituric acid-pyridine method with no statistically significant difference at 95% confidence level.

  14. On the Catalytic Effect of Water in the Intramolecular Diels–Alder Reaction of Quinone Systems: A Theoretical Study

    Directory of Open Access Journals (Sweden)

    Jorge Soto-Delgado

    2012-11-01

    Full Text Available The mechanism of the intramolecular Diels–Alder (IMDA reaction of benzoquinone 1, in the absence and in the presence of three water molecules, 1w, has been studied by means of density functional theory (DFT methods, using the M05-2X and B3LYP functionals for exploration of the potential energy surface (PES. The energy and geometrical results obtained are complemented with a population analysis using the NBO method, and an analysis based on the global, local and group electrophilicity and nucleophilicity indices. Both implicit and explicit solvation emphasize the increase of the polarity of the reaction and the reduction of activation free energies associated with the transition states (TSs of this IMDA process. These results are reinforced by the analysis of the reactivity indices derived from the conceptual DFT, which show that the increase of the electrophilicity of the quinone framework by the hydrogen-bond formation correctly explains the high polar character of this intramolecular process. Large polarization at the TSs promoted by hydrogen-bonds and implicit solvation by water together with a high electrophilicity-nucleophilicity difference consistently explains the catalytic effects of water molecules.

  15. Evaluating the Catalytic Effects of Carbon Materials on the Photocatalytic Reduction and Oxidation Reactions of TiO2

    International Nuclear Information System (INIS)

    TiO2 composites with seven different carbon materials (activated carbons, graphite, carbon fibers, single-walled carbon nanotubes, multi-walled carbon nanotubes, graphene oxides, and reduced graphene oxides) that are virgin or treated with nitric acid are prepared through an evaporation method. The photocatalytic activities of the as-prepared samples are evaluated in terms of H2 production from aqueous methanol solution (photo-catalytic reduction: PCR) and degradation of aqueous pollutants (phenol, methylene blue, and rhodamine B) (photocatalytic oxidation: PCO) under AM 1.5-light irradiation. Despite varying effects depending on the kinds of carbon materials and their surface treatment, composites typically show enhanced PCR activity with maximum 50 times higher H2 production as compared to bare TiO2. Conversely, the carbon-induced synergy effects on PCO activities are insignificant for all three substrates. Colorimetric quantification of hydroxyl radicals supports the absence of carbon effects. However, platinum deposition on the binary composites displays the enhanced effect on both PCR and PCO reactions. These differing effects of carbon materials on PCR and PCO reactions of TiO2 are discussed in terms of physicochemical properties of carbon materials, coupling states of TiO2/carbon composites, interfacial charge transfers. Various surface characterizations of composites (UV-Vis diffuse reflectance, SEM, FTIR, surface area, electrical conductivity, and photoluminescence) are performed to gain insight on their photocatalytic redox behaviors

  16. Catalytic degradation of methylene blue by Fenton like system:model to the environmental reaction

    Institute of Scientific and Technical Information of China (English)

    Sanjay R. Thakare

    2004-01-01

    To develop more efficient chemical methods for the demineralization of organic pollutants from waterbodies, which one was also mimic to the nature, a degradation of methylene blue by Fe( Ⅲ ) and H2O2 in theabsence of light instead of Fe( Ⅱ ) and H2O2 was studied. Results showed that use of Fe ( Ⅲ ) is more promisingthan Fe( Ⅱ ). The present study reflects that Fenton reaction is more efficient, in the presence of a small amount ofsalicylic acid is added which is a one of the priority pollutant.

  17. Mechanism of catalytic action of oxide systems in reactions of aldehyde oxidation to carboxylic acids

    International Nuclear Information System (INIS)

    Mechanism of selective action of oxide catalysts (on the base of V2O4, MoO3) of aldehyde oxidation to acids is considered, reaction acrolein oxidation to acrylic acid is taken as an example. Multistage mechanism of the process is established; it involves consequent transformation of coordination-bonded aldehyde into carbonyl-bonded aldehyde and symmetric carboxylate. Principles of active surface construction are formulated, they take into account the activity of stabilization center of concrete intermediate compound and bond energy of oxygen with surface. (author)

  18. Screening of catalytic oxygen reduction reaction activity of metal-doped graphene by density functional theory

    Science.gov (United States)

    Chen, Xin; Chen, Shuangjing; Wang, Jinyu

    2016-08-01

    Graphene doping is a promising direction for developing effective oxygen reduction reaction (ORR) catalysts. In this paper, we computationally investigated the ORR performance of 10 kinds of metal-doped graphene (M-G) catalysts, namely, Al-, Si-, Mn-, Fe-, Co-, Ni-, Pd-, Ag-, Pt-, and Au-G. The results shown that the binding energies of the metal atoms incorporated into the graphene vacancy are higher than their bulk cohesive energies, indicating the formed M-G catalysts are even more stable than the corresponding bulk metal surfaces, and thus avoid the metals dissolution in the reaction environment. We demonstrated that the linear relation among the binding energies of the ORR intermediates that found on metal-based materials does not hold for the M-G catalysts, therefore a single binding energy of intermediate alone is not sufficient to evaluate the ORR activity of an arbitrary catalyst. By analysis of the detailed ORR processes, we predicted that the Au-, Co-, and Ag-G materials can be used as the ORR catalysts.

  19. Lewis base activation of Lewis acids: catalytic, enantioselective vinylogous aldol addition reactions.

    Science.gov (United States)

    Denmark, Scott E; Heemstra, John R

    2007-07-20

    The generality of Lewis base catalyzed, Lewis acid mediated, enantioselective vinylogous aldol addition reactions has been investigated. The combination of silicon tetrachloride and chiral phosphoramides is a competent catalyst for highly selective additions of a variety of alpha,beta-unsaturated ketone-, 1,3-diketone-, and alpha,beta-unsaturated amide-derived dienolates to aldehydes. These reactions provided high levels of gamma-site selectivity for a variety of substitution patterns on the dienyl unit. Both ketone- and morpholine amide-derived dienol ethers afforded high enantio- and diastereoselectivity in the addition to conjugated aldehydes. Although alpha,beta-unsaturated ketone-derived dienolate did not react with aliphatic aldehydes, alpha,beta-unsaturated amide-derived dienolates underwent addition at reasonable rates affording high yields of vinylogous aldol product. The enantioselectivities achieved with the morpholine derived-dienolate in the addition to aliphatic aldehydes was the highest afforded to date with the silicon tetrachloride-chiral phosphoramide system. Furthermore, the ability to cleanly convert the morpholine amide to a methyl ketone was demonstrated. PMID:17583959

  20. 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

  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 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

  2. New catalytic reaction of elemental sulfur with acetylenes by the action of cobalt complexes

    Energy Technology Data Exchange (ETDEWEB)

    Dzhemilev, U.M.; Selimov, F.A.; Khafizov, V.R.; Khalilov, L.M.; Tolstikov, G.A.

    1986-11-20

    The authors report that the reaction of 1-hexyne with CS/sub 2/ taken in 3:1 mole ratio by the action of a catalyst prepared by the reduction of Co(2-ethylhexanoate)/sub 2/ by triethylaluminum in the presence of absolute DMSO (Co:Al:DMSO = 1:3:10-20) in absolute toluene solution at 150/sup 0/C for 6 h gives a 1:1 mixture of stereoisomeric 1,2-dithia-3,6-dibutyl-3,5-cyclohexadienes in about 40% total yield. By analogy, 1-hexyne and S/sub 8/ (S/sub ..cap alpha../-cyclooctasulfane) give 40% disulfides, 15% 2,4-dibutylthiophene, and about 45% of a mixture of 1,3,4- and 1,3,5-tributylbenzenes in 45% total yield identified by comparison with authentic samples.

  3. Catalytic activity trends of oxygen reduction reaction for nonaqueous Li-air batteries.

    Science.gov (United States)

    Lu, Yi-Chun; Gasteiger, Hubert A; Shao-Horn, Yang

    2011-11-30

    We report the intrinsic oxygen reduction reaction (ORR) activity of polycrystalline palladium, platinum, ruthenium, gold, and glassy carbon surfaces in 0.1 M LiClO(4) 1,2-dimethoxyethane via rotating disk electrode measurements. The nonaqueous Li(+)-ORR activity of these surfaces primarily correlates to oxygen adsorption energy, forming a "volcano-type" trend. The activity trend found on the polycrystalline surfaces was in good agreement with the trend in the discharge voltage of Li-O(2) cells catalyzed by nanoparticle catalysts. Our findings provide insights into Li(+)-ORR mechanisms in nonaqueous media and design of efficient air electrodes for Li-air battery applications. PMID:22044022

  4. Compartmentalization and Cell Division through Molecular Discreteness and Crowding in a Catalytic Reaction Network

    Directory of Open Access Journals (Sweden)

    Atsushi Kamimura

    2014-10-01

    Full Text Available Explanation of the emergence of primitive cellular structures from a set of chemical reactions is necessary to unveil the origin of life and to experimentally synthesize protocells. By simulating a cellular automaton model with a two-species hypercycle, we demonstrate the reproduction of a localized cluster; that is, a protocell with a growth-division process emerges when the replication and degradation speeds of one species are respectively slower than those of the other species, because of overcrowding of molecules as a natural outcome of the replication. The protocell exhibits synchrony between its division process and replication of the minority molecule. We discuss the effects of the crowding molecule on the formation of primitive structures. The generality of this result is demonstrated through the extension of our model to a hypercycle with three molecular species, where a localized layered structure of molecules continues to divide, triggered by the replication of a minority molecule at the center.

  5. Reproduction of a Protocell by Replication of a Minority Molecule in a Catalytic Reaction Network

    Science.gov (United States)

    Kamimura, Atsushi; Kaneko, Kunihiko

    2010-12-01

    For understanding the origin of life, it is essential to explain the development of a compartmentalized structure, which undergoes growth and division, from a set of chemical reactions. In this study, a hypercycle with two chemicals that mutually catalyze each other is considered in order to show that the reproduction of a protocell with a growth-division process naturally occurs when the replication speed of one chemical is considerably slower than that of the other chemical, and molecules are crowded as a result of replication. It is observed that the protocell divides after a minority molecule is replicated at a slow synthesis rate, and thus, a synchrony between the reproduction of a cell and molecule replication is achieved. The robustness of such protocells against the invasion of parasitic molecules is also demonstrated.

  6. Copper(I Complexes of Mesoionic Carbene: Structural Characterization and Catalytic Hydrosilylation Reactions

    Directory of Open Access Journals (Sweden)

    Stephan Hohloch

    2015-04-01

    Full Text Available Two series of different Cu(I-complexes of “click” derived mesoionic carbenes are reported. Halide complexes of the type (MICCuI (with MIC = 1,4-(2,6-diisopropyl-phenyl-3-methyl-1,2,3-triazol-5-ylidene (for 1b, 1-benzyl-3-methyl-4-phenyl-1,2,3-triazol-5-ylidene (for 1c and cationic complexes of the general formula [Cu(MIC2]X (with MIC =1,4-dimesityl-3-methyl-1,2,3-triazol-5-ylidene, X = CuI2− (for 2á, 1,4-dimesityl-3-methyl-1,2,3-triazol-5-ylidene, X = BF4− (for 2a, 1,4-(2,6-diisopropylphenyl-3-methyl-1,2,3-triazol-5-ylidene, X = BF4− (for 2b, 1-benzyl-3-methyl-4-phenyl-1,2,3-triazol-5-ylidene, X = BF4− (for 2c have been prepared from CuI or [Cu(CH3CN4](BF4 and the corresponding ligands, respectively. All complexes were characterized by elemental analysis and standard spectroscopic methods. Complexes 2á and 1b were studied by single-crystal X-ray diffraction analysis. Structural analysis revealed 2á to adopt a cationic form as [Cu(MIC2](CuI2 and comparison of the NMR spectra of 2á and 2a confirmed this conformation in solution. In contrast, after crystallization complex 1b was found to adopt the desired neutral form. All complexes were tested for the reduction of cyclohexanone under hydrosilylation condition at elevated temperatures. These complexes were found to be efficient catalysts for this reaction. 2c was also found to catalyze this reaction at room temperature. Mechanistic studies have been carried out as well.

  7. Cage-like copper(II) silsesquioxanes: transmetalation reactions and structural, quantum chemical, and catalytic studies.

    Science.gov (United States)

    Bilyachenko, Alexey N; Dronova, Marina S; Yalymov, Alexey I; Lamaty, Frédéric; Bantreil, Xavier; Martinez, Jean; Bizet, Christelle; Shul'pina, Lidia S; Korlyukov, Alexander A; Arkhipov, Dmitry E; Levitsky, Mikhail M; Shubina, Elena S; Kirillov, Alexander M; Shul'pin, Georgiy B

    2015-06-01

    The transmetalation of bimetallic copper-sodium silsesquioxane cages, namely, [(PhSiO1.5 )10 (CuO)2 (NaO0.5 )2 ] ("Cooling Tower"; 1), [(PhSiO1.5 )12 (CuO)4 (NaO0.5 )4 ] ("Globule"; 2), and [(PhSiO1.5 )6 (CuO)4 (NaO0.5 )4 (PhSiO1.5 )6 ] ("Sandwich"; 3), resulted in the generation of three types of hexanuclear cylinder-like copper silsesqui- oxanes, [(PhSiO1.5 )12 (CuO)6 (C4 H9 OH)2 (C2 H5 OH)6 ] (4), [(PhSiO1.5 )12 (CuO)6 (C4 H8 O2 )4 (PhCN)2 (MeOH)4 ] (5), and [(PhSiO1.5 )12 (CuO)6 (NaCl)(C4 H8 O2 )12 (H2 O)2 ] (6). The products show a prominent "solvating system-structure" dependency, as determined by X-ray diffraction. Topological analysis of cages 1-6 was also performed. In addition, DFT theory was used to examine the structures of the Cooling Tower and Cylinder compounds, as well as the spin density distributions. Compounds 1, 2, and 5 were applied as catalysts for the direct oxidation of alcohols and amines into the corresponding amides. Compound 6 is an excellent catalyst in the oxidation reactions of benzene and alcohols. PMID:25950426

  8. Multifunctional phosphine stabilized gold nanoparticles: an active catalytic system for three-component coupling reaction.

    Science.gov (United States)

    Borah, Bibek Jyoti; Borah, Subrat Jyoti; Dutta, Dipak Kumar

    2013-07-01

    Multifunctional phosphine based ligands, 1,1,1-tris(diphenylphosphinomethyl)ethane [CH3C(CH2 PPh2)3][P3] and 1,1,1-tris(diphenylphosphinomethyl)ethane trisulphide [CH3C(CH2P(S)Ph2)3][P3S3] have been introduced to stabilize Au(o)-nanoparticles having small core diameter and narrow size distribution. The Au(o)-nanoparticles were synthesized by the reduction of HAuCl4 precursor with NaBH4 in the presence of ligand P3 or P3S3 using two phases, one pot reaction at room temperature. The Au(o)-nanoparticles exhibit face centered cubic (fcc) lattice having different crystalline shape i.e., single crystallite stabilized by P3 while P3S3 forms decahedral shapes. Surface plasmon bands at -520 nm and TEM study indicate particle size below 2 and 4 nm for Au(o)-nanoparticles stabilized by P3 and P3S3 respectively, which are attributable to the stronger interaction of Au(o) (Soft) with P (Soft) than Au(o) (Soft) with S (less Softer than P). Au(o)-nanoparticles stabilized by P3S3 shows higher thermal stability than that of P3. The synthesized Au(o)-nanoparticles serve as an efficient catalyst for one-pot, three-component (A3) coupling of an aldehyde, an amine and an alkyne via C-H alkyne-activation to synthesize propargylamines (85-96%) without any additives and precaution to exclude air. PMID:23901533

  9. Robust non-carbon titanium nitride nanotubes supported Pt catalyst with enhanced catalytic activity and durability for methanol oxidation reaction

    International Nuclear Information System (INIS)

    By the combination of solvothermal alcoholysis and post-nitriding method, titanium nitride nanotubes (TiN NTs), with high surface area, hollow and interior porous structure are prepared successfully and used at a support for Pt nanoparticles. The TiN NTs supported Pt (Pt/TiN NTs) catalyst displays enhanced activity and durability towards methanol oxidation reaction (MOR) compared with the commercial Pt/C (E-TEK) catalyst. X ray diffraction (XRD), nitrogen adsorption/desorption, transmission electron microscopy (TEM) and X-ray photoelectron spectroscopy (XPS) measurements are performed to investigate the physicochemical properties of the synthesized catalyst. SEM and TEM images reveal that the wall of the TiN NTs is porous and Pt nanoparticles supported on the dendritic TiN nanocrystals exhibit small size and good dispersion. Effects of inherent corrosion-resistant, tubular and porous nanostructures and electron transfer due to the strong metal–support interactions of TiN NTs contribute to the enhanced catalytic activity and stability of Pt/TiN NTs towards the MOR

  10. Carboxylic acid-grafted mesoporous material and its high catalytic activity in one-pot three-component coupling reaction

    Energy Technology Data Exchange (ETDEWEB)

    Gomes, Ruth; Bhaumik, Asim [Department of Materials Science, Indian Association for the Cultivation of Science, Jadavpur, Kolkata 700032 (India); Dutta, Saikat [Department of Chemical Engineering, National Taiwan University, Taipei 10617, Taiwan (China)

    2014-11-01

    A new carboxylic acid functionalized mesoporous organic polymer has been synthesized via in situ radical polymerization of divinylbenzene and acrylic acid using a mesoporous silica as a seed during the polymerization process under solvothermal conditions. The mesoporous material MPDVAA-1 has been thoroughly characterized employing powder XRD, solid state {sup 13}C cross polarization magic angle spinning-nuclear magnetic resonance, FT-IR spectroscopy, N{sub 2} sorption, HR-TEM, and NH{sub 3} temperature programmed desorption-thermal conductivity detector (TPD-TCD) analysis to understand its porosity, chemical environment, bonding, and surface properties. The mesoporous polymer was used as a catalyst for a three comp onent Biginelli condensation between various aldehydes, β-keto esters, and urea/thioureas to give 3,4-dihydropyrimidine-2(1H)-ones. The reactions were carried out under conventional heating as well as solvent-free microwave irradiation of solid components, and in both the cases, the mesoporous polymer MPDVAA-1 proved to be a powerful, robust, and reusable catalyst with high catalytic efficiency.

  11. Carboxylic acid-grafted mesoporous material and its high catalytic activity in one-pot three-component coupling reaction

    Directory of Open Access Journals (Sweden)

    Ruth Gomes

    2014-11-01

    Full Text Available A new carboxylic acid functionalized mesoporous organic polymer has been synthesized via in situ radical polymerization of divinylbenzene and acrylic acid using a mesoporous silica as a seed during the polymerization process under solvothermal conditions. The mesoporous material MPDVAA-1 has been thoroughly characterized employing powder XRD, solid state 13C cross polarization magic angle spinning-nuclear magnetic resonance, FT-IR spectroscopy, N2 sorption, HR-TEM, and NH3 temperature programmed desorption-thermal conductivity detector (TPD-TCD analysis to understand its porosity, chemical environment, bonding, and surface properties. The mesoporous polymer was used as a catalyst for a three comp onent Biginelli condensation between various aldehydes, β-keto esters, and urea/thioureas to give 3,4-dihydropyrimidine-2(1H-ones. The reactions were carried out under conventional heating as well as solvent-free microwave irradiation of solid components, and in both the cases, the mesoporous polymer MPDVAA-1 proved to be a powerful, robust, and reusable catalyst with high catalytic efficiency.

  12. Theoretical insights on the catalytic activity and mechanism for oxygen reduction reaction at Fe and P codoped graphene.

    Science.gov (United States)

    He, Feng; Li, Kai; Xie, Guangyou; Wang, Ying; Jiao, Menggai; Tang, Hao; Wu, Zhijian

    2016-05-14

    The non-precious metal graphene catalyst doped with Fe-Px are recently proposed as a promising candidate in substituting Pt for catalyzing oxygen reduction reaction (ORR) in fuel cells. Systematic DFT calculations are performed to investigate the catalytic activity and the ORR mechanism on the Fe-Px (x = 1-4) system in acid medium in this work. Our results indicated that the configuration with one Fe and two P atoms codoped at zigzag edge site (Fe-P2-zig-G) is the most stable, in excellent agreement with the experimental observation that the ratio of Fe and P is nearly 1 : 2. The four-electron reduction mechanism for ORR on the Fe-P2-zig-G is via the competing OOH hydrogenation pathways (to form either OH + OH or O + H2O). The rate determining step is the O2 hydrogenation with an energy barrier of 0.43 eV, much smaller that of calculated 0.80 eV for pure Pt. In addition, the highest energy barrier of the studied ORR mechanism is the O2 dissociation with an energy barrier of 0.70 eV, a value also smaller than that of pure Pt. This demonstrated that the zigzag edge site of the Fe-P2 codoped graphene should be active for the ORR. PMID:27094325

  13. Reaction Mechanism for the Formation of Nitrogen Oxides (NO x ) During Coke Oxidation in Fluidized Catalytic Cracking Units

    KAUST Repository

    Chaparala, Sree Vidya

    2015-06-11

    Fluidized catalytic cracking (FCC) units in refineries process heavy feedstock obtained from crude oil distillation. While cracking feed, catalysts get deactivated due to coke deposition. During catalyst regeneration by burning coke in air, nitrogen oxides (NOx) are formed. The increase in nitrogen content in feed over time has resulted in increased NOx emissions. To predict NOx concentration in flue gas, a reliable model for FCC regenerators is needed that requires comprehensive understanding and accurate kinetics for NOx formation. Based on the nitrogen-containing functional groups on coke, model molecules are selected to study reactions between coke-bound nitrogen and O2 to form NO and NO2 using density functional theory. The reaction kinetics for the proposed pathways are evaluated using transition state theory. It is observed that the addition of O2 on coke is favored only when the free radical is present on the carbon atom instead of nitrogen atom. Thus, NOx formation during coke oxidation does not result from the direct attack by O2 on N atoms of coke, but from the transfer of an O atom to N from a neighboring site. The low activation energies required for NO formation indicate that it is more likely to form than NO2 during coke oxidation. The favorable pathways for NOx formation that can be used in FCC models are identified. Copyright © 2015 Taylor & Francis Group, LLC.

  14. Memorable Experiences with Sad Music—Reasons, Reactions and Mechanisms of Three Types of Experiences

    Science.gov (United States)

    Peltola, Henna-Riikka

    2016-01-01

    Reactions to memorable experiences of sad music were studied by means of a survey administered to a convenience (N = 1577), representative (N = 445), and quota sample (N = 414). The survey explored the reasons, mechanisms, and emotions of such experiences. Memorable experiences linked with sad music typically occurred in relation to extremely familiar music, caused intense and pleasurable experiences, which were accompanied by physiological reactions and positive mood changes in about a third of the participants. A consistent structure of reasons and emotions for these experiences was identified through exploratory and confirmatory factor analyses across the samples. Three types of sadness experiences were established, one that was genuinely negative (Grief-Stricken Sorrow) and two that were positive (Comforting Sorrow and Sweet Sorrow). Each type of emotion exhibited certain individual differences and had distinct profiles in terms of the underlying reasons, mechanisms, and elicited reactions. The prevalence of these broad types of emotional experiences suggested that positive experiences are the most frequent, but negative experiences were not uncommon in any of the samples. The findings have implications for measuring emotions induced by music and fiction in general, and call attention to the non-pleasurable aspects of these experiences. PMID:27300268

  15. Memorable Experiences with Sad Music-Reasons, Reactions and Mechanisms of Three Types of Experiences.

    Directory of Open Access Journals (Sweden)

    Tuomas Eerola

    Full Text Available Reactions to memorable experiences of sad music were studied by means of a survey administered to a convenience (N = 1577, representative (N = 445, and quota sample (N = 414. The survey explored the reasons, mechanisms, and emotions of such experiences. Memorable experiences linked with sad music typically occurred in relation to extremely familiar music, caused intense and pleasurable experiences, which were accompanied by physiological reactions and positive mood changes in about a third of the participants. A consistent structure of reasons and emotions for these experiences was identified through exploratory and confirmatory factor analyses across the samples. Three types of sadness experiences were established, one that was genuinely negative (Grief-Stricken Sorrow and two that were positive (Comforting Sorrow and Sweet Sorrow. Each type of emotion exhibited certain individual differences and had distinct profiles in terms of the underlying reasons, mechanisms, and elicited reactions. The prevalence of these broad types of emotional experiences suggested that positive experiences are the most frequent, but negative experiences were not uncommon in any of the samples. The findings have implications for measuring emotions induced by music and fiction in general, and call attention to the non-pleasurable aspects of these experiences.

  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. The reaction of fish to light (laboratory experiments)

    International Nuclear Information System (INIS)

    The results of the study on the title subject can contribute to the realization of decreasing the damage to sea trout, caused by cooling water input of thermal power plants and turbines of hydroelectric power plants. Trout can be diverted from the cooling water inlets by means of light screens. Bench-scale experiments were executed to analyze the impact of the rate of the water flow to the reaction of young sea trout (smolts) to light. Also the effectiveness of light bulbs and fluorescence lamps are compared. The smolts show a clear aversion to a small amount of light. For a high water flow and in standing water the aversion reaction to light is considerably smaller or absent

  18. Reaction-induced strain localization: Torsion experiments on dolomite

    Science.gov (United States)

    Delle Piane, Claudio; Burlini, Luigi; Grobety, Bernard

    2007-04-01

    We investigated the mechanical behaviour and microstructural evolution of a dolomite marble from Mt. Frerone (Adamello, N-Italy) during decarbonation to calcite and periclase in torsion experiments. Tests were performed in a Paterson gas-medium apparatus on cylindrical samples of 10 mm diameter and 10 mm length. Experiments were conducted at 800 °C, 300 MPa confining pressure under both vented and non-vented conditions, up to a maximum bulk shear strain of about γ = 1.8, at different strain rates (3 × 10 - 5 s - 1 up to 3 × 10 - 4 s - 1 ). Under hydrostatic conditions the nominal equilibrium P(CO 2) should be around 100 MPa, but in the vented experiments the CO 2 was free to escape, causing the breakdown of dolomite. During the decomposition, deformation was systematically localized at the ends of the specimens, near the porous spacers into a fine-grained mixture of calcite and periclase. Due to the low permeability of the marble, pore fluid could not escape from the central part of the sample building up CO 2 pressure which suppressed the decarbonation reaction. The fluid pressure embrittled the material and caused the development of en-echelon tension fractures, inclined opposite to the sense of shear. We conclude that decarbonation produced a weak polyphase matrix composed of submicron sized reaction products. Such a small grain size induced strain localization which was probably promoted by a switch from grain-size insensitive to grain-size sensitive deformation mechanism.

  19. Catalytic reactions of C4 hydrocarbons on the fluid catalytic cracking catalyst%C4烃类在催化裂化催化剂上催化转化反应的研究

    Institute of Scientific and Technical Information of China (English)

    闫平祥; 孟祥海; 徐春明; 高金森

    2008-01-01

    The catalytic reactions of C4 hydrocarbons on a fluid catalytic cracking (FCC) catalyst were studied in a confined fluidized bed reactor. The effect of reaction temperature and space velocity on product yields and distribution was investigated. The results show that the FCC catalyst has the good performance of aromatization and cracking of C4 hydrocarbons and can be used to produce propylene and aromatics under the suitable reaction conditions. It is mainly the butylene in the C4 hydrocarbons that undergoes catalytic reactions over the FCC catalyst and butane is hard to convert. Low reaction temperature favors the production of aromatics, while high reaction temperature favors the production of propylene. Low space velocity is beneficial to promote the conversion of butylene and the production of both aromatics and propylene. According to the bimolecular mechanism and reaction results, the reaction network for the catalytic reactions of C4 hydrocarbons on the FCC catalyst is proposed. The analysis on the this reaction mechanism indicates that the main reason of resulting in the lower yields of ethylene and propylene could be the poor secondary cracking performances of C5 and C6 olefins formed in the catalytic conversion of C4 hydrocarbons on the FCC catalyst.%利用小型固定流化床实验装置,对C4烃类在催化裂化催化剂上催化转化反应规律进行了实验研究,考察了不同反应温度及空速对C4烃类催化转化反应的产物分布和组成的影响.实验结果表明,催化裂化催化剂对C4烃类具有一定芳构化和裂化性能,在适宜的反应条件下,可增产芳烃和丙烯;在C4烃类催化转化过程中,丁烯是主要的反应物,而丁烷几乎不反应;低反应温度有利于增产芳烃,高反应温度有利于增产丙烯.较低的空速对增产芳烃和丙烯都有利.根据双分子反应机理和反应结果 ,建立了C4烃类在催化裂化催化剂上催化转化过程的反应网络.对C4烃类催化转化

  20. Oxidation of rhodium (3) by periodate in alkali medium and chemiluminescent catalytic reaction of luminol with periodate in the presence of rhodium (3)

    International Nuclear Information System (INIS)

    A new reaction of oxidation of Rh (3) chloride by a periodate to Rh (5) has been found to take place in an alkaline medium. Oxidation of luminol by the compound Rh (5) is chemiluminescent. These reactions proceed at a considerable rate. Catalytic action of Rh (3) in the chemiluminescent reaction of luminol with the periodate includes the above reactions with the redox cycle Rh (3) reversible Rh (5). The reaction of oxidation of Rh (3) by the periodate can be used for photometric determination of 20-100 μkg of rhodium in 5 ml of a finite volume as a violent colour compound Rh (5) with the absorption maximum at lambda 600 nm. Time of full colour development is 8-10 min without heating the solutions; colour stability is 16 hrs

  1. Catalytic distillation structure

    Science.gov (United States)

    Smith, Jr., Lawrence A.

    1984-01-01

    Catalytic distillation structure for use in reaction distillation columns, a providing reaction sites and distillation structure and consisting of a catalyst component and a resilient component intimately associated therewith. The resilient component has at least about 70 volume % open space and being present with the catalyst component in an amount such that the catalytic distillation structure consist of at least 10 volume % open space.

  2. Design and Synthesis of Chiral Zn2+ Complexes Mimicking Natural Aldolases for Catalytic C–C Bond Forming Reactions in Aqueous Solution

    Directory of Open Access Journals (Sweden)

    Susumu Itoh

    2014-01-01

    Full Text Available Extending carbon frameworks via a series of C–C bond forming reactions is essential for the synthesis of natural products, pharmaceutically active compounds, active agrochemical ingredients, and a variety of functional materials. The application of stereoselective C–C bond forming reactions to the one-pot synthesis of biorelevant compounds is now emerging as a challenging and powerful strategy for improving the efficiency of a chemical reaction, in which some of the reactants are subjected to successive chemical reactions in just one reactor. However, organic reactions are generally conducted in organic solvents, as many organic molecules, reagents, and intermediates are not stable or soluble in water. In contrast, enzymatic reactions in living systems proceed in aqueous solvents, as most of enzymes generally function only within a narrow range of temperature and pH and are not so stable in less polar organic environments, which makes it difficult to conduct chemoenzymatic reactions in organic solvents. In this review, we describe the design and synthesis of chiral metal complexes with Zn2+ ions as a catalytic factor that mimic aldolases in stereoselective C–C bond forming reactions, especially for enantioselective aldol reactions. Their application to chemoenzymatic reactions in aqueous solution is also presented.

  3. First-principles quantum mechanical investigations: Catalytic reactions of furfural on Pd(111) and at the water/Pd(111) interface

    Science.gov (United States)

    Xue, Wenhua

    Bio-oils have drawn more and more attention from scientists as a promising new clean, cheap energy source. One of the most interesting relevant issues is the effect of catalysts on the catalytic reactions that are used for producing bio-oils. Furfural, as a very important intermediate during these reactions, has attracted significant studies. However, the effect of catalysts, including particularly the liquid/solid interface formed by a metal catalyst and liquid water, in the catalytic reactions involving furfural still remains elusive. In this research, we performed ab initio molecular dynamics simulations and first-principles density-functional theory calculations to investigate the atomic-scale mechanisms of catalytic hydrogenation of furfural on the palladium surface and at the liquid/state interface formed by the palladium surface and liquid water. We studied all the possible mechanisms that lead to formation of furfuryl alcohol (FOL), formation of tetrahydrofurfural (THFAL), and formation of tetrahydrofurfurfuryl alcohol (THFOL). We found that liquid water plays a significant role in the hydrogenation reactions. During the reaction in the presence of water and the palladium catalyst, in particular, water directly participates in the hydrogenation of the aldehyde group of furfural and facilitates the formation of FOL by reducing the activation energy. Our calculations show that water provides hydrogen for the hydrogenation of the aldehyde group, and at the same time, a pre-existing hydrogen atom, which is resulted from dissociation of molecular hydrogen (experimentally, molecular hydrogen is always supplied for hydrogenation) on the palladium surface, is bonded to water, making the water molecule intact in structure. In the absence of water, on the other hand, formation of FOL and THFAL on the palladium surface involves almost the same energy barriers, suggesting a comparable selectivity. Overall, as water reduces the activation energy for the formation of FOL

  4. Enhancing catalytic performance of palladium in gold and palladium alloy nanoparticles for organic synthesis reactions through visible light irradiation at ambient temperatures.

    Science.gov (United States)

    Sarina, Sarina; Zhu, Huaiyong; Jaatinen, Esa; Xiao, Qi; Liu, Hongwei; Jia, Jianfeng; Chen, Chao; Zhao, Jian

    2013-04-17

    The intrinsic catalytic activity of palladium (Pd) is significantly enhanced in gold (Au)-Pd alloy nanoparticles (NPs) under visible light irradiation at ambient temperatures. The alloy NPs strongly absorb light and efficiently enhance the conversion of several reactions, including Suzuki-Miyaura cross coupling, oxidative addition of benzylamine, selective oxidation of aromatic alcohols to corresponding aldehydes and ketones, and phenol oxidation. The Au/Pd molar ratio of the alloy NPs has an important impact on performance of the catalysts since it determines both the electronic heterogeneity and the distribution of Pd sites at the NP surface, with these two factors playing key roles in the catalytic activity. Irradiating with light produces an even more profound enhancement in the catalytic performance of the NPs. For example, the best conversion rate achieved thermally at 30 °C for Suzuki-Miyaura cross coupling was 37% at a Au/Pd ratio of 1:1.86, while under light illumination the yield increased to 96% under the same conditions. The catalytic activity of the alloy NPs depends on the intensity and wavelength of incident light. Light absorption due to the Localized Surface Plasmon Resonance of gold nanocrystals plays an important role in enhancing catalyst performance. We believe that the conduction electrons of the NPs gain the light absorbed energy producing energetic electrons at the surface Pd sites, which enhances the sites' intrinsic catalytic ability. These findings provide useful guidelines for designing efficient catalysts composed of alloys of a plasmonic metal and a catalytically active transition metal for various organic syntheses driven by sunlight. PMID:23566035

  5. Catalytic diastereoselective tandem conjugate addition-elimination reaction of Morita-Baylis-Hillman C adducts by C-C bond cleavage

    KAUST Repository

    Yang, Wenguo

    2012-02-08

    Through the cleavage of the C-C bond, the first catalytic tandem conjugate addition-elimination reaction of Morita-Baylis-Hillman C adducts has been presented. Various S N2′-like C-, S-, and P-allylic compounds could be obtained with exclusive E configuration in good to excellent yields. The Michael product could also be easily prepared by tuning the β-C-substituent group of the α-methylene ester under the same reaction conditions. Calculated relative energies of various transition states by DFT methods strongly support the observed chemoselectivity and diastereoselectivity. © 2012 Wiley-VCH Verlag GmbH&Co. KGaA, Weinheim.

  6. High Pressure Scanning Tunneling Microscopy Studies of Adsorbate Structure and Mobility during Catalytic Reactions. Novel Design of an Ultra High Pressure, High Temperature Scanning Tunneling Microscope System for Probing Catalytic Conversions

    International Nuclear Information System (INIS)

    The aim of the work presented therein is to take advantage of scanning tunneling microscope's (STM) capability for operation under a variety of environments under real time and at atomic resolution to monitor adsorbate structures and mobility under high pressures, as well as to design a new generation of STM systems that allow imaging in situ at both higher pressures (35 atm) and temperatures (350 C). The design of a high pressure, high temperature scanning tunneling microscope system, that is capable of monitoring reactions in situ at conditions from UHV and ambient temperature up to 1 atm and 250 C, is briefly presented along with vibrational and thermal analysis, as this system serves as a template to improve upon during the design of the new ultra high pressure, high temperature STM. Using this existing high pressure scanning tunneling microscope we monitored the co-adsorption of hydrogen, ethylene and carbon dioxide on platinum (111) and rhodium (111) crystal faces in the mTorr pressure range at 300 K in equilibrium with the gas phase. During the catalytic hydrogenation of ethylene to ethane in the absence of CO the metal surfaces are covered by an adsorbate layer that is very mobile on the time scale of STM imaging. We found that the addition of CO poisons the hydrogenation reaction and induces ordered structures on the single crystal surfaces. Several ordered structures were observed upon CO addition to the surfaces pre-covered with hydrogen and ethylene: a rotated (√19 x √19)R23.4o on Pt(111), and domains of c(4 x 2)-CO+C2H3, previously unobserved (4 x 2)-CO+3C2H3, and (2 x 2)-3CO on Rh(111). A mechanism for CO poisoning of ethylene hydrogenation on the metal single crystals was proposed, in which CO blocks surface metal sites and reduces adsorbate mobility to limit adsorption and reaction rate of ethylene and hydrogen. In order to observe heterogeneous catalytic reactions that occur well above ambient pressure and temperature that more closely resemble

  7. N2O Catalytic Decomposition – from Laboratory Experiment to Industry Reactor

    Czech Academy of Sciences Publication Activity Database

    Obalová, L.; Jirátová, Květa; Karásková, K.; Chromčáková, Ž.

    2012-01-01

    Roč. 191, č. 1 (2012), s. 116-120. ISSN 0920-5861 R&D Projects: GA TA ČR TA01020336 Institutional support: RVO:67985858 Keywords : N2O * catalytic decomposition * fixed bed reactor Subject RIV: CI - Industrial Chemistry, Chemical Engineering Impact factor: 2.980, year: 2012

  8. The reaction of fish to light (laboratory experiments)

    International Nuclear Information System (INIS)

    The results of the study on the title subject can contribute to the realization of decreasing the damage to eel, caused by cooling water input of thermal power plants and turbines of hydroelectric power plants. Eel can be diverted from the cooling water inlets by means of light screens. Bench-scale experiments were executed to analyze the impact of the rate of the water flow to the reaction of eel to light. Also the effectiveness of light bulbs and fluorescence lamps are compared. Eel shows a clear aversion to a small amount of light. The diversion percentage decreases with a higher velocity of the water flow. Application of energy-efficient fluorescent lamps is considered to be a good option for diversion light systems

  9. Fabrication and characterisation of gold nano-particle modified polymer monoliths for flow-through catalytic reactions and their application in the reduction of hexacyanoferrate

    International Nuclear Information System (INIS)

    Polymer monoliths in capillary (100 μm i.d.) and polypropylene pipette tip formats (vol: 20 μL) were modified with gold nano-particles (AuNP) and subsequently used for flow-through catalytic reactions. Specifically, methacrylate monoliths were modified with amine-reactive monomers using a two-step photografting method and then reacted with ethylenediamine to provide amine attachment sites for the subsequent immobilisation of 4 nm, 7 nm or 16 nm AuNP. This was achieved by flushing colloidal suspensions of gold nano-particles through each aminated polymer monolith which resulted in a multi-point covalent attachment of gold via the lone pair of electrons on the nitrogen of the free amine groups. Field emission scanning electron microscopy and scanning capacitively coupled conductivity detection was used to characterise the surface coverage of AuNP on the monoliths. The catalytic activity of AuNP immobilised on the polymer monoliths in both formats was then demonstrated using the reduction of Fe(III) to Fe(II) by sodium borohydride as a model reaction by monitoring the reduction in absorbance of the hexacyanoferrate (III) complex at 420 nm. Catalytic activity was significantly enhanced on monoliths modified with smaller AuNP with almost complete reduction (95 %) observed when using monoliths agglomerated with 7 nm AuNPs. (author)

  10. Effect of calcination temperature on structural properties and catalytic activity in oxidation reactions of LaNiO3 perovskite prepared by Pechini method

    Institute of Scientific and Technical Information of China (English)

    K.Rida; M.A.Pe(n)a; E.Sastre; A.Martínez-Arias

    2012-01-01

    The study presented the preparation of the perovskite oxide LaNiO3 by the complex citrate method,paying particular attention to evolution of its formation from the amorphous precursor with varied calcination temperatures.The products obtained after heat treatment under air between 200 and 800 ℃ were characterized by X-ray diffraction (XRD),thermogravimetric and differential thermal analysis (TG-DTA),Fourier transform infrared spectroscopy (FTIR),SBET measurements and X-ray photoelectron spectroscopy (XPS).The results showed the formation of a single phase with perovskite structure from ca.550 ℃.Tests on the two catalytic oxidation reactions of C3H6 and CO over the system calcined between mentioned temperatures were examined on the basis of characterization results and showed that optimum catalytic properties for such reactions were achieved for the perovskite calcined at 600 ℃.In turn,correlations between redox and catalytic properties were established on the basis of thermogravimetric temperature programmed reduction (TPR) analysis.

  11. Catalytic ignition of light hydrocarbons

    Institute of Scientific and Technical Information of China (English)

    K. L. Hohn; C.-C. Huang; C. Cao

    2009-01-01

    Catalytic ignition refers to phenomenon where sufficient energy is released from a catalytic reaction to maintain further reaction without additional extemai heating. This phenomenon is important in the development of catalytic combustion and catalytic partial oxidation processes, both of which have received extensive attention in recent years. In addition, catalytic ignition studies provide experimental data which can be used to test theoretical hydrocarbon oxidation models. For these reasons, catalytic ignition has been frequently studied. This review summarizes the experimental methods used to study catalytic ignition of light hydrocarbons and describes the experimental and theoretical results obtained related to catalytic ignition. The role of catalyst metal, fuel and fuel concentration, and catalyst state in catalytic ignition are examined, and some conclusions are drawn on the mechanism of catalytic ignition.

  12. A Monte Carlo Simulation of a Monomer Dimer CO-O2 Catalytic Reaction on the Surface and Subsurface of a Face-centered Cubic Lattice

    Institute of Scientific and Technical Information of China (English)

    K.Iqbal; A.Basit

    2011-01-01

    @@ The presence of oxygen in the subsurface in monomer-dimer reactions(CO-O2 and NO-CO)is observed experimentally.The effect of subsurface oxygen on a CO-O2 catalytic reaction on a face-centered cubic(FCC)lattice is studied using Monte Carlo simulation.The effect of adding subsurface neighbours on the phase diagram is also extensively explored.It is observed that the subsurface oxygen totally eliminates the typical second order phase transition.It is also shown that the introduction of the diffusion of O atoms and the subsurface of the FCC lattice shifts the single transition point towards the stoichiometric ratio.%The presence of oxygen in the subsurface in monomer-dimer reactions (CO-O2 and NO-CO) is observed experimentally. The effect of subsurface oxygen on a CO-O2 catalytic reaction on a face-centered cubic (FCC) lattice is studied using Monte Carlo simulation. The effect of adding subsurface neighbours on the phase diagram is also extensively explored. It is observed that the subsurface oxygen totally eliminates the typical second order phase transition. It is also shown that the introduction of the diffusion of O atoms and the subsurface of the FCC lattice shifts the single transition point towards the stoichiometric ratio.

  13. Catalytic distillation process

    Science.gov (United States)

    Smith, Jr., Lawrence A.

    1982-01-01

    A method for conducting chemical reactions and fractionation of the reaction mixture comprising feeding reactants to a distillation column reactor into a feed zone and concurrently contacting the reactants with a fixed bed catalytic packing to concurrently carry out the reaction and fractionate the reaction mixture. For example, a method for preparing methyl tertiary butyl ether in high purity from a mixed feed stream of isobutene and normal butene comprising feeding the mixed feed stream to a distillation column reactor into a feed zone at the lower end of a distillation reaction zone, and methanol into the upper end of said distillation reaction zone, which is packed with a properly supported cationic ion exchange resin, contacting the C.sub.4 feed and methanol with the catalytic distillation packing to react methanol and isobutene, and concurrently fractionating the ether from the column below the catalytic zone and removing normal butene overhead above the catalytic zone.

  14. Effect of Ni+2-substituted Fe2TiO5 on the H2-reduction and CO2 Catalytic Decomposition Reactions at 500℃

    Institute of Scientific and Technical Information of China (English)

    M.H.Khedr

    2006-01-01

    CO2 is a major component of the greenhouse gases, which causes the global warming. To reduce CO2 gas,high activity nanosized Ni+2 substituted Fe2TiO5 samples were synthesized by conventional ceramic method.The effect of the composition of the synthesized ferrite on the H2-reduction and CO2-catalytic decomposition was investigated. Fe2TiO5 (iron titanate) phase that has a nanocrystallite size of ~80 nm is formed as a result of heating Fe2O3 and TiO2 while the addition of NiO leads to the formation of new phases (~80 nm)NiTiO3 and NiFe2O4, but the mixed solid of NiO and Fe2O3 results in the formation of NiFe2O4 only.Samples with Ni+2=0 shows the lowest reduction extent (20%); as the extent of Ni+2 increases, the extent of reduction increases. The increase in the reduction percent is attributed to the presence of NiTiO3 and NiFe2O4 phases, which are more reducible phases than Fe2TiO5. The CO2 decomposition reactions were monitored by thermogravimetric analysis (TGA) experiments. The oxidation of the H2-reduced Ni+2 substituted Fe2TiO5 at 500℃ was investigated. As Ni+2 increases, the rate of reoxidation increases. Samples with the highest reduction extents gave the highest reoxidation extent, which is attributed to the highly porous nature and deficiency in oxygen due to the presence of metallic Fe, Ni and/or FeNi alloy. X-ray diffraction (XRD) and transmission electron microscopy (TEM) of oxidized samples show also the presence of carbon in the sample containing Ni+2>0, which appears in the form of nanotubes (25 nm).

  15. Verification experiment of EPR paradox by (d, 2He) reaction

    International Nuclear Information System (INIS)

    FBR paradox which was brought forward by Einstein, Podolsky and Rosen is expressed by Bell's inequality of spin correlation theoretically. In principle it is possible to verify the inequality by measuring spin correlation between two particles having spin 1/2 from a decay of 1S0 experimentally. Most of the past experiments to verify the inequality, however, have been performed by using photons. On the other hand, only one experiment by using hadron system was carried out by Lamehi and Mitting, where the [1S0] state was produced by proton-proton scattering at first, and then the spin orientations after the scattering were measured. Unfortunately, there exit some sources of ambiguity to reach definite conclusion from their result because the experiment was done at rather high energy of 13.5 MeV. In the experiment planned by the present author it is designed to overcome the experimental difficulties, which Lamehi and Mitting encountered, by (1) generating high purity singlet [1S0] state of two protons by (d, 2He) type nuclear reaction at intermediate energy range, and by (2) developing high performance spin-correlation polarimeter which can analyze spins of two protons simultaneously to minimize the systematic errors. The excitation energy of 2He corresponding to the proton-proton relative energy can be experimentally controlled. An idea singlet is realized by choosing the state with sufficiently small relative energy. It is planned to measure the spin correlation function by using SMART (Swinger and Magnetic Analyzer with Rotator and Twister) at RIKEN Accelerator Research Facility. Einstein POLarimeter (EPOL) to be installed on the second focal plane of SMART is under development, with which high precision measurements of spin orientations of two high energy protons simultaneously coming into limited space from 2He decay are made selecting the subject events from very many background events. Monte Carlo simulation predicts the possibility to verify the breaking of

  16. Thieme Chemistry Journal Awardees - Where are They Now? Catalytic Transport with an Amine Carrier in a Fluorous Triphasic Reaction

    OpenAIRE

    Montanari, Vittorio; Yu, Marvin S.; Curran, Dennis P.

    2009-01-01

    Several aromatic aldehydes are transported by a fluorous amine from one organic phase through a fluorous phase to another organic phase. The derived imines react with phenylhydrazine to immobilize the transported product as a hydrazone and release the amine for reuse. In this way, catalytic transport is accomplished for the first time.

  17. Upward Trend in Catalytic Efficiency of Rare-Earth Triflate Catalysts in Friedel-Crafts Aromatic Sulfonylation Reactions

    DEFF Research Database (Denmark)

    Duus, Fritz; Le, Thach Ngoc; Nguyen, Vo Thu An

    2014-01-01

    90 % were achieved for short irradiation periods. This was the case especially for Tm(OTf)3, Yb(OTf)3, and Lu(OTf)3, of which Yb(OTf)3 was the most efficient. The upward trend in catalytic efficiency therefore correlates with the lanthanide sequence in the periodic table. The results can be explained...

  18. Catalytic ozonation not relying on hydroxyl radical oxidation: A selective and competitive reaction process related to metal-carboxylate complexes

    KAUST Repository

    Zhang, Tao

    2014-01-01

    Catalytic ozonation following non-hydroxyl radical pathway is an important technique not only to degrade refractory carboxylic-containing organic compounds/matter but also to avoid catalyst deactivation caused by metal-carboxylate complexation. It is unknown whether this process is effective for all carboxylates or selective to special molecule structures. In this work, the selectivity was confirmed using O3/(CuO/CeO2) and six distinct ozone-resistant probe carboxylates (i.e., acetate, citrate, malonate, oxalate, pyruvate and succinate). Among these probe compounds, pyruvate, oxalate, and citrate were readily degraded following the rate order of oxalate>citrate>pyruvate, while the degradation of acetate, malonate, and succinate was not promoted. The selectivity was independent on carboxylate group number of the probe compounds and solution pH. Competitive degradation was observed for carboxylate mixtures following the preference order of citrate, oxalate, and finally pyruvate. The competitive degradation was ascribed to competitive adsorption on the catalyst surface. It was revealed that the catalytically degradable compounds formed bidentate chelating or bridging complexes with surface copper sites of the catalyst, i.e., the active sites. The catalytically undegradable carboxylates formed monodentate complexes with surface copper sites or just electrostatically adsorbed on the catalyst surface. The selectivity, relying on the structure of surface metal-carboxylate complex, should be considered in the design of catalytic ozonation process. © 2013 Elsevier B.V.

  19. Synthesis and Catalytic Activity of Ruthenium-Indenylidene Complexes for Olefin Metathesis: Microscale Experiments for the Undergraduate Inorganic or Organometallic Laboratories

    Science.gov (United States)

    Pappenfus, Ted M.; Hermanson, David L.; Ekerholm, Daniel P.; Lilliquist, Stacie L.; Mekoli, Megan L.

    2007-01-01

    A series of experiments for undergraduate laboratory courses (e.g., inorganic, organometallic or advanced organic) have been developed. These experiments focus on understanding the design and catalytic activity of ruthenium-indenylidene complexes for olefin metathesis. Included in the experiments are the syntheses of two ruthenium-indenylidene…

  20. Exam experience and some reactions to exam stress.

    Science.gov (United States)

    Simić, N; Manenica, I

    2012-01-01

    The aim of this study was to assess the effects of previous exam experience on some psychophysiological reactions before, during and after repeated exams. A sample of 15 first year psychology students took part in the study. While the subjects were expecting a oral exam for the first time, their levels of exam apprehension, high activation and state anxiety were measured a day before, an hour before the exam and the following day. Furthermore, subjects' cardiac R-R intervals were continuously recorded from five minutes before the exam to five minutes after the exam. Four, out of 15 subjects, passed the exams at first sitting, while the rest of them failed and had to repeat it. These 11 students underwent the same procedure for the second time. The levels of exam apprehension, high activation and anxiety did not show any differences between the first and the second exam sittings. R-R interval parameters indicated a higher stress before and after the second exam sitting, while the stress level was more or less the same during both exams. PMID:22567840

  1. Modelling of non-catalytic reactions in a gas-solid trickle flow reactor: dry, regenerative flue gas desulphurization using a silica-supported copper oxide sorbent

    OpenAIRE

    Kiel, J.H.A.; De Prins, W.; Swaaij, van, W.P.M.

    1992-01-01

    A one-dimensional, two-phase dispersed plug flow model has been developed to describe the steady-state performance of a relatively new type of reactor, the gas-solid trickle flow reactor (GSTFR). In this reactor, an upward-flowing gas phase is contacted with as downward-flowing dilute solids phase over an inert packing. The model is derived from the separate mass heat balances for both the gas and (porous) solids phases for the case of a non-catalytic gas-solid reaction, which is first-order ...

  2. 菲加氢裂化制BTX的催化反应研究%Research on Catalytic Reaction of Phenanthrene Hydrocracking to Produce Xylene

    Institute of Scientific and Technical Information of China (English)

    杨健; 吴倩; 朱志荣

    2012-01-01

    采用性能较优的6% Ni/USY催化剂,进行菲加氢裂化制取苯、甲苯、二甲苯(BTX)的反应研究.探讨了不同反应压强、反应温度及进料速率对反应的影响,实验结果表明:反应压强4MPa、反应温度420℃、进料速率<0.27mL/min时,转化率可达95%左右,且BTX的选择性约60%,并结合反应机理对实验结果进行了探讨.%The 6% Ni/USY catalyst with good performance was used for the catalytic reaction of phenanthrene hydrocracking to obtain benzene, toluene and xylene (BTX). The impact of different reaction pressure, reaction temperature and the flow rate of the feed on the reaction was studied. The results showed that the phenanthrene conversion rate could reach about 95%, and the BTX selectivity could be about 60%, when the reaction conditions were 4 MPa, 420 ℃ and 0.27 mL/min. The test results were probed into with reference to the reaction mechanism.

  3. Model Experiment of Thermal Runaway Reactions Using the Aluminum-Hydrochloric Acid Reaction

    Science.gov (United States)

    Kitabayashi, Suguru; Nakano, Masayoshi; Nishikawa, Kazuyuki; Koga, Nobuyoshi

    2016-01-01

    A laboratory exercise for the education of students about thermal runaway reactions based on the reaction between aluminum and hydrochloric acid as a model reaction is proposed. In the introductory part of the exercise, the induction period and subsequent thermal runaway behavior are evaluated via a simple observation of hydrogen gas evolution and…

  4. Synthesis, characterization and catalytic properties of nanocrystaline Y{sub 2}O{sub 3}-coated TiO{sub 2} in the ethanol dehydration reaction

    Energy Technology Data Exchange (ETDEWEB)

    Fajardo, Humberto Vieira [Universidade Federal de Ouro Preto (UFOP), MG (Brazil). Departamento de Quimica; Longo, Elson [Universidade Estadual Paulista (UNESP), Araraquara, SP (Brazil). Departamento de Fisico-Quimica; Leite, Edson Roberto; Libanori, Rafael [Universidade Federal de Sao Carlos (UFSCar), SP (Brazil). Departamento de Quimica; Probst, Luiz Fernando Dias [Universidade Federal de Santa Catarina (UFSC), Florianopolis, SC (Brazil). Departamento de Quimica; Carreno, Neftali Lenin Villarreal [Universidade Federal de Pelotas (UFPel), RS (Brazil). Departamento de Quimica Analitica e Inorganica

    2012-03-15

    In the present study, TiO{sub 2} nano powder was partially coated with Y{sub 2}O{sub 3} precursors generated by a sol-gel modified route. The system of nanocoated particles formed an ultra thin structure on the TiO{sub 2} surfaces. The modified nanoparticles were characterized by high resolution transmission electron microscopy (HR-TEM), X-ray diffraction (XRD) analysis, Zeta potential and surface area through N{sub 2} physisorption measurements. Bioethanol dehydration was used as a probe reaction to investigate the modifications on the nanoparticles surface. The process led to the obtainment of nanoparticles with important surface characteristics and catalytic behavior in the bioethanol dehydration reaction, with improved activity and particular selectivity in comparison to their non-coated analogs. The ethylene production was disfavored and selectivity toward acetaldehyde, hydrogen and ethane increased over modified nanoparticles. (author)

  5. Nickel(II) complexes containing ONS donor ligands: Synthesis, characterization, crystal structure and catalytic application towards C-C cross-coupling reactions

    Indian Academy of Sciences (India)

    Panneerselvam Anitha; Rajendran Manikandan; Paranthaman Vijayan; Govindan Prakash; Periasamy Viswanathamurthi; Ray Jay Butcher

    2015-04-01

    Nickel(II) complexes containing thiosemicarbazone ligands [Ni(L)2] (1-3) (L = 9,10-phenanthrenequinonethiosemicarbazone (HL1), 9,10-phenanthrenequinone-N-methylthio semicarbazone (HL2) and 9, 10-phenanthrenequinone-N-phenylthiosemicarbazone (HL3)) have been synthesized and characterized by elemental analysis and spectroscopic (IR, UV-Vis, 1H, 13C-NMR and ESI mass) methods. The molecular structures of complexes 1 and 2 were identified by means of single-crystal X-ray diffraction analysis. The analysis revealed that the complexes possess a distorted octahedral geometry with the ligand coordinating in a uni-negative tridentate ONS fashion. The catalytic activity of complexes towards some C–C coupling reactions (viz., Kumada-Corriu, Suzuki-Miyaura and Sonogashira) has been examined. The complexes behave as efficient catalysts in the Kumada-Corriu and Sonogashira coupling reactions rather than Suzuki-Miyaura coupling.

  6. 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...

  7. Synthesis, characterization and catalytic properties of nanocrystaline Y2O3-coated TiO2 in the ethanol dehydration reaction

    International Nuclear Information System (INIS)

    In the present study, TiO2 nano powder was partially coated with Y2O3 precursors generated by a sol-gel modified route. The system of nanocoated particles formed an ultra thin structure on the TiO2 surfaces. The modified nanoparticles were characterized by high resolution transmission electron microscopy (HR-TEM), X-ray diffraction (XRD) analysis, Zeta potential and surface area through N2 physisorption measurements. Bioethanol dehydration was used as a probe reaction to investigate the modifications on the nanoparticles surface. The process led to the obtainment of nanoparticles with important surface characteristics and catalytic behavior in the bioethanol dehydration reaction, with improved activity and particular selectivity in comparison to their non-coated analogs. The ethylene production was disfavored and selectivity toward acetaldehyde, hydrogen and ethane increased over modified nanoparticles. (author)

  8. Self-assembly growth of alloyed NiPt nanocrystals with holothuria-like shape for oxygen evolution reaction with enhanced catalytic activity

    Directory of Open Access Journals (Sweden)

    Tao Ding

    2016-01-01

    Full Text Available Self-assembly growth of alloyed NiPt nanocrystals with holothuria-like wire shape has been achieved via a facile and moderate hydrothermal process at 120 °C for 1 h from the reaction of nickel nitrate and chloroplatinic acid in alkaline solution in the presence of ethanediamine and hydrazine hydrate. The holothuria-like alloyed NiPt wires are Ni-rich in composition (Ni23.6Pt and uniform in diameter with many tiny tips outstretched from the wires surface. The holothuria-like wires are assembled from granular subunits with the assistance of capping molecular of ethanediamine and the wires display an improved oxygen evolution reaction catalytic activity.

  9. Self-assembly growth of alloyed NiPt nanocrystals with holothuria-like shape for oxygen evolution reaction with enhanced catalytic activity

    Science.gov (United States)

    Ding, Tao; Wang, Wenliang; Zhou, Xiaoli; Zhang, Li; Wang, Chunde; Jiang, Jun; Yang, Weilai; Yang, Qing

    2016-01-01

    Self-assembly growth of alloyed NiPt nanocrystals with holothuria-like wire shape has been achieved via a facile and moderate hydrothermal process at 120 °C for 1 h from the reaction of nickel nitrate and chloroplatinic acid in alkaline solution in the presence of ethanediamine and hydrazine hydrate. The holothuria-like alloyed NiPt wires are Ni-rich in composition (Ni23.6Pt) and uniform in diameter with many tiny tips outstretched from the wires surface. The holothuria-like wires are assembled from granular subunits with the assistance of capping molecular of ethanediamine and the wires display an improved oxygen evolution reaction catalytic activity.

  10. Three model space experiments on chemical reactions. [Gibbs adsorption, equilibrium shift and electrodeposition

    Science.gov (United States)

    Grodzka, P.; Facemire, B.

    1977-01-01

    Three investigations conducted aboard Skylab IV and Apollo-Soyuz involved phenomena that are of interest to the biochemistry community. The formaldehyde clock reaction and the equilibrium shift reaction experiments conducted aboard Apollo Soyuz demonstrate the effect of low-g foams or air/liquid dispersions on reaction rate and chemical equilibrium. The electrodeposition reaction experiment conducted aboard Skylab IV demonstrate the effect of a low-g environment on an electrochemical displacement reaction. The implications of the three space experiments for various applications are considered.

  11. Steam reforming of methane over Ni catalysts prepared from hydrotalcite-type precursors:Catalytic activity and reaction kinetics

    Institute of Scientific and Technical Information of China (English)

    Yang Qi; Zhenmin Cheng; Zhiming Zhou

    2015-01-01

    Ni/Mg–Al catalysts derived from hydrotalcite-type precursors were prepared by a co-precipitation technique and applied to steam reforming of methane. By comparison with Ni/γ-Al2O3 and Ni/α-Al2O3 catalysts prepared by in-cipient wetness impregnation, the Ni/Mg–Al catalyst presented much higher activity as a result of higher specific surface area and better Ni dispersion. The Ni/Mg–Al catalyst with a Ni/Mg/Al molar ratio of 0.5:2.5:1 exhibited the highest activity for steam methane reforming and was selected for kinetic investigation. With external and inter-nal diffusion limitations eliminated, kinetic experiments were carried out at atmospheric pressure and over a temperature range of 823–973 K. The results demonstrated that the overal conversion of CH4 and the conversion of CH4 to CO2 were strongly influenced by reaction temperature, residence time of reactants as wel as molar ratio of steam to methane. A classical Langmuir–Hinshelwood kinetic model proposed by Xu and Froment (1989) fitted the experimental data with excellent agreement. The estimated adsorption parameters were consistent thermodynamical y.

  12. Catalytic Coanda combustion

    Energy Technology Data Exchange (ETDEWEB)

    Coleman, J.D.; Smith, A.G.; Kopmels, M.

    1992-09-16

    A catalytic reaction is enhanced by the use of the Coanda effect to maximise contact between reactant and catalyst. A device utilising this principle comprises a Coanda surface which directs the flow of fuel from a slot to form a primary jet which entrains the surrounding ambient air and forms a combustible mixture for reaction on a catalytic surface. The Coanda surface may have an internal or external nozzle which may be axi-symmetric or two-dimensional. (author)

  13. Elementary steps of the catalytic NO{sub x} reduction with NH{sub 3}: Cluster studies on reaction paths and energetics at vanadium oxide substrate

    Energy Technology Data Exchange (ETDEWEB)

    Gruber, M.; Hermann, K. [Inorganic Chemistry Department, Fritz-Haber-Institut der Max-Planck-Gesellschaft, Faradayweg 4-6, 14195 Berlin (Germany)

    2013-12-28

    We consider different reaction scenarios of the selective catalytic reduction (SCR) of NO in the presence of ammonia at perfect as well as reduced vanadium oxide surfaces modeled by V{sub 2}O{sub 5}(010) without and with oxygen vacancies. Geometric and energetic details as well as reaction paths are evaluated using extended cluster models together with density-functional theory. Based on earlier work of adsorption, diffusion, and reaction of the different surface species participating in the SCR we confirm that at Brønsted acid sites (i.e., OH groups) of the perfect oxide surface nitrosamide, NH{sub 2}NO, forms a stable intermediate. Here adsorption of NH{sub 3} results in NH{sub 4} surface species which reacts with gas phase NO to produce the intermediate. Nitrosamide is also found as intermediate of the SCR near Lewis acid sites of the reduced oxide surface (i.e., near oxygen vacancies). However, here the adsorbed NH{sub 3} species is dehydrogenated to surface NH{sub 2} before it reacts with gas phase NO to produce the intermediate. The calculations suggest that reaction barriers for the SCR are overall higher near Brønsted acid sites of the perfect surface compared with Lewis acid sites of the reduced surface, examined for the first time in this work. The theoretical results are consistent with experimental findings and confirm the importance of surface reduction for the SCR process.

  14. Operando magnetic resonance: monitoring the evolution of conversion and product distribution during the heterogeneous catalytic ethene oligomerisation reaction.

    Science.gov (United States)

    Roberts, S Tegan; Renshaw, Matthew P; Lutecki, Michal; McGregor, James; Sederman, Andrew J; Mantle, Mick D; Gladden, Lynn F

    2013-11-18

    Operando magnetic resonance (MR) spectroscopy has been used to follow an ethene oligomerisation reaction performed at 110 °C, 28 barg over a 1 wt% Ni/SiO2-Al2O3 catalyst. Spectra acquired over the timecourse of the reaction allow the calculation of conversion and product distribution as a function of time-on-stream. PMID:24088715

  15. 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)

  16. Multinucleon photonuclear reactions on {sup 209}Bi: Experiment and evaluation

    Energy Technology Data Exchange (ETDEWEB)

    Belyshev, S.S.; Kurilik, A.S. [Lomonosov Moscow State University, Department of Physics, Moscow (Russian Federation); Filipescu, D.M.; Tesileanu, O. [Extreme Light Infrastructure - Nuclear Physics/Horia Hulubei National Institute for R and D in Physics and Nuclear Engineering, Bucharest-Magurele (Romania); Gheoghe, I. [Extreme Light Infrastructure - Nuclear Physics/Horia Hulubei National Institute for R and D in Physics and Nuclear Engineering, Bucharest-Magurele (Romania); University of Bucharest, Faculty of Physics, Bucharest-Magurele (Romania); Ishkhanov, B.S. [Lomonosov Moscow State University, Department of Physics, Moscow (Russian Federation); Skobeltsyn Institute of Nuclear Physics, Lomonosov Moscow State University, Moscow (Russian Federation); Khankin, V.V.; Kuznetsov, A.A.; Orlin, V.N.; Peskov, N.N.; Stopani, K.A.; Varlamov, V.V. [Skobeltsyn Institute of Nuclear Physics, Lomonosov Moscow State University, Moscow (Russian Federation)

    2015-06-15

    Photon activation technique using bremsstrahlug with end-point energy 55.6 MeV is used to induce photonuclear reactions in a {sup 209}Bi target. Absolute yields and integrated cross sections of multiparticle reactions (γ, 2n-6n), (γ, 4n1p), and (γ, 5n1p) are obtained. The results are compared to predictions of statistical models using systematical and microscopic description of photoabsorption and to the result of evaluation of the partial photoneutron reaction cross sections. Based on a comparison with existing experimental photoneutron cross sections and model calculations, we make a conclusion that neutron multiplicity assignment in available photoneutron cross sections on {sup 209}Bi can be corrected and evaluated cross sections of (γ, 1n) and (γ, 2n) are obtained that are in an agreement with the obtained experimental results. (orig.)

  17. Influence of ethanol on catalytic properties of vanadium (5) compounds in the reaction of hydrazine oxidation by cerium (4) sulfate

    International Nuclear Information System (INIS)

    A study was made of the effect of ethyl alcohol on the rate of oxidation of hydrazine by cerium sulphate in the presence and in the absence of vanadium compounds. The addition of ethyl alcohol accelerates the oxidation reaction. In the absence of the vanadium compounds acting as catalyst, the increase in the reaction rate is due to the formation of an intermediate complex between the oxidizing agent and the ethyl alcohol. The equilibrium constant for the reaction forming the intermediate complex with composition 1:1 is 0.70+-0.05, while the constant for the rate of decomposition of the intermediate product is 0.24 min-1. In the presence of the vanadium compounds an intermediate complex is formed between the catalyst and the ethyl alcohol. The equilibrium constant for the reaction forming this complex is 0.41+-0.03, and the constant for the rate of decomposition thereof is 0.44x105min-1. (author)

  18. Submonolayer-Pt-Coated Ultrathin Au Nanowires and Their Self-Organized Nanoporous Film: SERS and Catalysis Active Substrates for Operando SERS Monitoring of Catalytic Reactions.

    Science.gov (United States)

    Liu, Rui; Liu, Jing-Fu; Zhang, Zong-Mian; Zhang, Li-Qiang; Sun, Jie-Fang; Sun, Meng-Tao; Jiang, Gui-Bin

    2014-03-20

    For their unique properties, core-shell bimetal nanostructures are currently of immense interest. However, their synthesis is not a trivial work, and most works have been conducted on nanoparticles. We report herein a new synthetic tactic for submonolyer-Pt coated ultrathin Au nanowires (NWs). Besides providing a strong electromagnetic field for Raman signal enhancing, the underlined Au NWs markedly enhanced the catalytic activity of Pt atoms through increasing their dispersity and altering their electronic state. The integration of excellent SERS and high catalytic activity within Au@Pt NWs enable it work as platform for catalyzed reaction study. As a proof of principle, the self-organized Au@Pt NWs thin film is employed in operando SERS monitoring of the p-nitrothiophenol reduction process. In addition to providing kinetic data for structure-activity relationship study, the azo-intermidate independent path is also directly witnessed. This synthetic tactic can be extended to other metals, thus offering a general approach to modulate the physical/chemical properties of both core and shell metals. PMID:26270975

  19. Synthesis of ceramic catalytic system based on CuO/CeO2 for preferential oxidation reaction of CO

    International Nuclear Information System (INIS)

    The aim this is work is to develop catalysts based on CuO/CeO2 by means two different types of synthesis methods: combustion synthesis and Pechini. CuO/CeO2 catalysts were synthesized with 0.5 mol of CuO for both synthesis methods used. The catalysts were characterized by XRD with the Rietveld refinement, EDX and textural analysis by the BET method. The results show that both methods of synthesis led to the formation of catalysts with segregated phases formed on the structures of the obtained materials, such segregated phases were formed by the presence of catalytic active species CuO and these phases had different characteristics depending on the type of method synthesis used. Small differences were observed in the evaluation of textural characteristics of the catalysts developed in this work according to the synthesis method employed. (author)

  20. Influence of the particle size of zeolite HZSM-5 on the catalytic performance in the ethene-to-propene reaction

    Energy Technology Data Exchange (ETDEWEB)

    Follmann, S.; Ernst, S. [Kaiserslautern Univ. (Germany). Dept. of Chemistry; Vetter, A.; Ripperger, S. [Kaiserslautern Univ. (Germany). Dept. of Mechanical and Process Engineering

    2013-11-01

    In this study, HZSM-5-type zeolites with comparable nSi/nAl-ratios but different crystallite sizes (6 {mu}m, 27 {mu}m, 40 {mu}m and 62 {mu}m) were synthesized and their physicochemical properties characterized by X-ray powder diffraction (XRD), scanning electron microscopy (SEM) and nitrogen physisorption. Their catalytic properties were explored in the acid-catalyzed conversion of ethene to propene (and higher hydrocarbons). The results show that there is a significant influence of the crystallite size of the zeolite catalyst on the activity and time-on-steam stability. While the yields of short-chain olefins do not significantly differ for all materials investigated, the formation of aromatics is significantly suppressed over the catalyst with the largest crystallite size. (orig.)

  1. 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.

  2. Isolation and Characterization of Well-Defined Silica-Supported Azametallacyclopentane: A Key Intermediate in Catalytic Hydroaminoalkylation Reactions

    KAUST Repository

    Hamzaoui, Bilel

    2015-09-25

    Intermolecular catalytic hydroaminoalkylation of unactivated alkene occurs with silica-supported azazirconacyclopropane [[TRIPLE BOND]Si[BOND]O[BOND]Zr(HNMe2)(η2-NMeCH2)(NMe2)]. Mechanistic studies were conducted using surface organometallic chemistry (SOMC) concepts to identify the key surface intermediates. The azametallacyclopentene intermediate {[TRIPLE BOND]Si[BOND]O[BOND]Zr(HNMe2)[η2-NMeCH2CH(Me)CH2](NMe2)} was isolated after treating with 1-propylene and characterized by FT-IR spectroscopy, elemental analysis, 1H 13C HETCOR, DARR SS-NMR and DQ TQ SS-NMR. The regeneration of the catalyst was conducted by dimethylamine protonolysis to yield the pure amine.

  3. Green synthesis of Pd/CuO nanoparticles by Theobroma cacao L. seeds extract and their catalytic performance for the reduction of 4-nitrophenol and phosphine-free Heck coupling reaction under aerobic conditions.

    Science.gov (United States)

    Nasrollahzadeh, Mahmoud; Sajadi, S Mohammad; Rostami-Vartooni, Akbar; Bagherzadeh, Mojtaba

    2015-06-15

    We report the green synthesis of palladium/CuO nanoparticles (Pd/CuO NPs) using Theobroma cacao L. seeds extract and their catalytic activity for the reduction of 4-nitrophenol and Heck coupling reaction under aerobic conditions. The catalyst was characterized using the powder XRD, TEM, EDS, UV-vis and FT-IR. This method has the advantages of high yields, elimination of surfactant, ligand and homogeneous catalysts, simple methodology and easy work up. The catalyst can be recovered from the reaction mixture and reused several times without any significant loss of catalytic activity. PMID:25721860

  4. Catalytic performance of the exchanged Y faujasites by Ce3+, La3+, UO22+, Co2+, Sr2+, Pb2+, Tl+ and NH4+ cations in the disproportionation reaction of toluene

    International Nuclear Information System (INIS)

    The catalytic performance of exchanged Y faujasites by Ce3+, La3+, UO22+, Co2+, Sr2+, Pb2+, Tl+ and NH4+ ions were studied in a disproportionation reaction in the gaseous phase. It was shown that total acidity generated by exchanged ions is responsible of the catalytic activity. Rare earths (cerium, lanthanum and uranium) catalysts have appreciable performance and allowed one to obtain an important xylenes proportion at 400 to 450 C. The decrease of xylenes and trimethyl-benzenes proportion in studied catalysts shows the implication of xylenes in toluene disproportionation reaction. (authors)

  5. Catalytic, Conjugate Reduction-Aldol Addition Reaction of β'Oxoal kyl α, β-Unsatu rated Carboxylates%Catalytic, Conjugate Reduction-Aldol Addition Reaction of β'Oxoal kyl α, β-Unsatu rated Carboxylates

    Institute of Scientific and Technical Information of China (English)

    郑爱军; 姜岚; 李争宁

    2012-01-01

    Intramolecular conjugate reduction-aldol addition reactions of β'-oxoalkyl a,fl-unsaturated carboxylates were performed in the presence of copper catalysts generated in situ from copper salts, phosphine ligands and silanes. Moderate to good yields and high diastereoselectivities were obtained in 15 min to 3 h using bis[(2-diphenyl- phosphino)phenyl] ether as the ligand.

  6. N-Methylphthalimide-substituted benzimidazolium salts and PEPPSI Pd–NHC complexes: synthesis, characterization and catalytic activity in carbon–carbon bond-forming reactions

    Science.gov (United States)

    Gök, Yetkin; İlhan, İlhan Özer

    2016-01-01

    Summary A series of novel benzimidazolium salts (1–4) and their pyridine enhanced precatalyst preparation stabilization and initiation (PEPPSI) themed palladium N-heterocyclic carbene complexes [PdCl2(NHC)(Py)] (5–8), where NHC = 1-(N-methylphthalimide)-3-alkylbenzimidazolin-2-ylidene and Py = 3-chloropyridine, were synthesized and characterized by means of 1H and 13C{1H} NMR, UV–vis (for 5–8), ESI-FTICR-MS (for 2, 4, 6–8) and FTIR spectroscopic methods and elemental analysis. The synthesized compounds were tested in Suzuki–Miyaura cross-coupling (for 1–8) and arylation (for 5–8) reactions. As catalysts, they demonstrated a highly efficient route for the formation of asymmetric biaryl compounds even though they were used in very low loading. For example, all compounds displayed good catalytic activity for the C–C bond formation of 4-tert-butylphenylboronic acid with 4-chlorotoluene. PMID:26877810

  7. 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

  8. Visual discrimination of phenolic group β₂-agonists and the ultrasensitive identification of their oxidation products by use of a tyrosinase-based catalytic reaction.

    Science.gov (United States)

    Xiong, Huayu; Guo, Chunhui; Liu, Ping; Xu, Wei; Zhang, Xiuhua; Wang, Shengfu

    2014-05-20

    The fast, visual discrimination of β2-agonist drugs is needed for the on-site screening of various types of β2-agonists in blood and urine samples. We developed a simple, rapid, one-step colorimetric method to detect phenolic β2-agonists by use of a tyrosinase catalytic reaction, which involved the oxidation of the phenol group on the benzene rings of β2-agonists. The enzymatic oxidation products of β2-agonists with phenolic groups exhibited different color transitions based on the different substituent groups on the aromatic ring, whereas β2-agonists with the aniline group or the resorcinol group remained colorless. This visual color discrepancy has been used to intuitively and conveniently differentiate the phenolic group β2-agonists, such as ractopamine, isoxsuprine, ritodrine, and fenoterol. The oxidation products of these compounds have been identified using mass spectrometry, and the possible reaction mechanisms between β2-agonists and tyrosinase have been deduced. The parameters that govern the analytical performance of the reaction product, including the pH of the buffer solution, the concentration of tyrosinase, and the incubation time, have been studied and optimized using ultraviolet-visible (UV-vis) spectroscopy and electrochemical methods. Under the optimal experimental conditions, the absorbance intensity and electrochemical signal were found to increase proportionally to the concentrations of the phenolic group β2-agonists, which gave a quantitative description of the β2-agonists in solution. PMID:24785981

  9. Non-thermal transient mobility of O2 in CO-O2 surface catalytic reaction: a Monte Carlo simulation study

    International Nuclear Information System (INIS)

    The catalytic oxidation of CO has already been studied over a square surface through Monte Carlo simulation via a model based on the Langmuir-Hinshelwood (LH) mechanism in which the dissociated adsorption of the O2 molecule is considered on a pair of vacancies found in the nearest neighbourhood. The results of this study are well known. Here, this reaction system has been studied on the basis of the precursor mechanism, which involves the motion of two oxygen precursors into the first and the third nearest neighbourhood. This study shows that contrary to the dimer-dimer model, the mobility of precursors into the third nearest neighbourhood has no significant effect on the phase diagram of the system. If the reaction of a precursor with chemisorbed oxygen atoms is allowed, the situation changes significantly. In this case, the mobility of precursors has the same effect as observed in the dimer-dimer model. We also have explored the effect of an experimentally observed hot atom adsorption mechanism on the phase diagram of the reaction system. When two oxygen precursors are adsorbed with an average distance of two lattice constants, the second-order phase transition is eliminated. The moment yCO departs from zero, the continuous production of CO2 starts and the phase diagram closely resembles the experimental one qualitatively

  10. NH3-SCR performance of fresh and hydrothermally aged Fe-ZSM-5 in standard and fast selective catalytic reduction reactions.

    Science.gov (United States)

    Shi, Xiaoyan; Liu, Fudong; Xie, Lijuan; Shan, Wenpo; He, Hong

    2013-04-01

    Hydrothermal stability is one of the challenges for the practical application of Fe-ZSM-5 catalysts in the selective catalytic reduction (SCR) of NO with NH3 (NH(3)-SCR) for diesel engines. The presence of NO(3) in the exhaust gases can enhance the deNOx activity because of the fast SCR reaction. In this work, a Fe-ZSM-5 catalyst was prepared by a solid-state ion-exchange method and was hydrothermally deactivated at 800 °C in the presence of 10% H(2)O. The activity of fresh and hydrothermal aged Fe-ZSM-5 catalysts was investigated in standard SCR (NO(2)/NOx = 0) and in fast SCR with NO(2)/NOx = 0.3 and 0.5. In standard SCR, hydrothermal aging of Fe-ZSM-5 resulted in a significant decrease of low-temperature activity and a slight increase in high-temperature activity. In fast SCR, NOx conversion over aged Fe-ZSM-5 was significantly increased but was still lower than that over fresh catalyst. Additionally, production of N(2)O in fast SCR was much more apparent over aged Fe-ZSM-5 than over fresh catalyst. We propose that, in fast SCR, the rate of key reactions related to NO is slower over aged Fe-ZSM-5 than over fresh catalyst, thus increasing the probabilities of side reactions involving the formation of N(2)O. PMID:23477804

  11. 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.

  12. 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.

  13. Multicomponent diffusional reactions in tool steels : Experiment and Theory

    OpenAIRE

    Lindwall, Greta

    2012-01-01

    Many phenomena determining the microstructure of a tool steel and consequently the properties of the material, are governed by multicomponent diffusion. The diffusion driven reactions that take place during, for example, tempering of a hot-work tool steel or when the microstructure develops during hot isostatic pressing of cold-work tool steel, are dependent on the types and amounts of alloying elements. In order for computational methods to be usable, these alloying effects need to be unders...

  14. Electron transfer reactions in chemistry. Theory and experiment

    OpenAIRE

    Marcus, Rudolph A.

    1997-01-01

    Since the late 1940s, the field of electron transfer processes has grown enormously, both in chemistry and biology. The development of the field, experimentally and theoretically, as well as its relation to the study of other kinds of chemical reactions, represents to us an intriguing history, one in which many threads have been brought together. In this lecture, some history, recent trends, and my own involvement in this research are described.

  15. Spontaneous adverse drug reaction monitoring in oncology: Our experience

    Directory of Open Access Journals (Sweden)

    K Kaur

    2015-01-01

    Full Text Available Background: Adverse drug reaction (ADR monitoring is slowly developing as an important aspect of healthcare. The aim of the study was to study the pattern of adverse drug reactions in the Oncology department of a tertiary care hospital. Materials And Methods: This was a prospective study conducted in the Oncology department of a tertiary care hospital in which ADRs were reported spontaneously. The ADRs were noted from 1st January, 2007 to 30th June, 2011. Following were noted: demographics, premedication (if any, diagnosis, chemotherapy (regimen, cycles, medication history, and alteration in the treatment or co morbidities, ADRs (severity and management. Adverse drug reactions were noted by patient interview, collaborating with information on file, recording changes in the prescribing chart and investigations, consulting the doctor on duty. Results: During this study period, there were total of 14,475 visits of patients from which 2500 ADRs were recorded. Maximum number of ADRs were noted with platinum compounds (25.52% followed by pyrimidine antagonists (19.88%. The most common malignancy reported in our hospital was Carcinoma breast (20% followed by leukemia (12% and Ca ovary (12%. Alopecia (27.76% was the most common ADR followed by anemia (7.48%, thrombocytopenia (6.96% and constipation (6.16%. Conclusion: Alopecia is the most common ADR and platinum compounds were responsible for the maximum number of ADRs. The most common carcinoma reported during this period was carcinoma breast.

  16. Stopped-in-loop flow analysis system for successive determination of trace vanadium and iron in drinking water using their catalytic reactions.

    Science.gov (United States)

    Ayala Quezada, Alejandro; Ohara, Keisuke; Ratanawimarnwong, Nuanlaor; Nacapricha, Duangjai; Murakami, Hiroya; Teshima, Norio; Sakai, Tadao

    2015-11-01

    An automated stopped-in-loop flow analysis (SILFA) system is proposed for the successive catalytic determination of vanadium and iron. The determination of vanadium was based on the p-anisidine oxidation by potassium bromate in the presence of Tiron as an activator to form a reddish dye, which has an absorption maximum at 510 nm. The selectivity of the vanadium determination was greatly improved by adding diphosphate as a masking agent of iron. For the iron determination, an iron-catalyzed oxidative reaction of p-anisidine by hydrogen peroxide with 1,10-phenanthroline as an activator to produce a reddish dye (510 nm) was employed. The SILFA system consisted of two peristaltic pumps, two six-port injection valves, a four-port selection valve, a heater device, a spectrophotometric detector and a data acquisition device. One six-port injection valve was used for the isolation of a mixed solution of standard/sample and reagent to promote each catalytic reaction, and another six-port injection valve was used for switching the reagent for vanadium or iron to achieve selective determination of each analyte. The above mentioned four-port selection valve was used to select standard solutions or sample. These three valves and the two peristaltic pumps were controlled by a built-in programmable logic controller in a touchscreen controller. The obtained results showed that the proposed SILFA monitoring system constituted an effective approach for the selective determination of vanadium and iron. The limits of detection, 0.052 and 0.55 µg L(-1), were obtained for vanadium and iron, respectively. The proposed system was successfully applied to drinking water samples without any preconcentration procedures. PMID:26452899

  17. Studies of the Catalytic Activity and Deactivation of Calcined Layered Double Hydroxides in the Reaction of Ethanol with Propylene Oxide

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    The reaction of ethanol with propylene oxide over calcined layered double hydroxides(CLDH) was investigated. The results show that CLDH has a good activity and a good selectivity, but the activity and the selectivity of CLDH decrease when CLDH reforms LDH- the so called "memory effect". The influence of the "memory effect" on the CLDH returning to LDH was studied by the hydration reaction. It is shown that the "memory effect" is not complete, and the decreases of the Mg/Al molar ratio of LDH and the crystallite size due to the increase of the hydration reaction time result in the drop of the activity and the selectivity.Keyworcds Ethanol, Propylene oxide, Calcined layered double hydroxide, "Memory effect", Hydration

  18. Tritium Labeled Gentamicin C: II.- Bioradiactive Degradation Products of Gentamicin by Catalytic H2O-3H Exchange Reaction

    International Nuclear Information System (INIS)

    The main bio radioactive degradation products from catalytic hydrogen exchange of gentamicin C, (C1 + C2 + Cla) in basic form, are generated by N-demethylation in 3-N and 6-N positions. Their structures were confirmed by 1HNMR and 13CNMR. These derivatives were fractionated by chromatography on silica gel. Antibacterial activities were similar to those of the parent antibiotics. Tritium exchange, under vacuum or nitrogen, is highly increased (4:1) when gentamicin are in basic form. In contrast with gentamicin sulfate, hydrolytic sub products as gramine, genta mines, garosamine and purpurosamines are practically absent. To properly optimize the exchange process, the composition of the gentamicin C complex must be taken into account. The exchange decreases in the order C2 > C1> Cla. Because of 6'-N-demethyl gentamicin C1 is C2, the radiochemical yield of C2 appears enhanced in the H2O-3H exchange of a mixture of them. Radioactivity distribution among the components and subunits of these three gentamicin were studied by strong and mild hydrolysis, and by methanolysis. (Author) 18 refs

  19. Tritium labeled Gentamicin C : II.- Bioradioactive products of Gentamicin by Catalytic H2O-3H exchange reaction

    International Nuclear Information System (INIS)

    The main bioradioactive degradation products from catalytic hydrogen exchange of gentamicin C, (C1 + C2 + C1a) in basic form, are generated by N-dimethylations in 3-N and 6'-N positions. Their structures were confirmed by HNMR and 13 CNMR. These derivatives were fractionated by chromatography on silica gel. Antibacterial activities were similar to those of the parent antibiotics. Tritium exchange, under vacuum or nitrogen, is highly increased (4:1) when gentamicina are in basic form. In contrast with gentamicin sulfate, hydrolytic subproducts as garamine, gentamicine, garosamine and purpurosamines are practically absent. To properly optimize the exchange process, the composition of the gentamicin C complex must be taken into account. The exchange decreases in the order C2 > C1 > C1a. Because of 6' -N-dimenthyl gentamicin C1 is C2, the radiochemical yield of C2 appears enhanced in the H2O-3H exchange of a mixture of them. Radioactivity distribution among the components and subunits of these three gentamicins were studied by stron and mild hydrolysis, and by methanolysis. (author)

  20. Evolution of nanoporous Pt-Fe alloy nanowires by dealloying and their catalytic property for oxygen reduction reaction

    Energy Technology Data Exchange (ETDEWEB)

    Shui, Jiang-Lan; Chen, Chen; Li, James C.M. [Material Science Program, University of Rochester, Rochester, NY (United States)

    2011-09-09

    The short life and high cost of carbon-supported Pt nanoparticle catalysts (Pt/C) are two main problems with proton exchange membrane fuel cells. Porous Pt alloy nanowires have more durability and catalytic activity than Pt/C. Dealloying is a facile way to make nanoporous Pt. However, the process of porosity formation is difficult to control. In this paper, electrospinning and chemical dealloying techniques are used to make long, thin and yet nanoporous Pt-Fe alloy nanowires. The evolution of nanoporosity is observed and studied. It is found that non-uniform composition in the precursor PtFe{sub 5} alloy nanowires helps the formation of nanoporous structure. The overall wire diameter is about 10-20 nm and the ligament diameter only 2-3 nm. These porous long nanowires interweave to form a self-supporting network with a high specific activity, 2.3 times that of conventional Pt/C catalysts, and also have better durability. (Copyright copyright 2011 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  1. Resting Study of Tracer Experiment on Catalytic Wet Oxidation Reactor under Micro-gravity and Earth Gravity Conditions

    Institute of Scientific and Technical Information of China (English)

    YANG Ji; JIA Jin-ping

    2005-01-01

    The International Space Station(ISS) employs catalytic wet oxidation carried out in a Volatile Reactor Assembly (VRA) for water recycling. Previous earth gravity experiments show that the VRA is very effective at removing polar,low molecular weight organics. To compare the reactor performance under micro-gravity and Earth gravity conditions,a tracer study was performed on a space shuttle in 1999 by using 0. 2% potassium carbonate as the chemical tracer.In this paper, the experimental data were analyzed and it is indicated that the reactor can be considered as a plug flow one under both micro-gravity and earth gravity experimental conditions. It has also been proved that dispersion is not important in the VRA reactor under the experimental conditions. Tracer retardation was observed in the experiments and it is most likely caused by catalyst adsorption. It is concluded that the following reasons may also have influence on the retardation of mean residence time: (1) the liquid can be held by appurtenances, which will retard the mean residence time; (2) the pores can hold the tracer, which can also retard the mean residence time.

  2. Characterization of catalytic supports based in mixed oxides for control reactions of NO and N{sub 2}O; Caracterizacion de soportes cataliticos basados en oxidos mixtos para reacciones de control de NO y N{sub 2}O

    Energy Technology Data Exchange (ETDEWEB)

    Garcia C, M.A.; Perez H, R.; Gomez C, A.; Diaz, G. [Instituto Nacional de Investigaciones Nucleares, A.P. 18-1027, 11801 Mexico D.F. (Mexico)

    1999-07-01

    The catalytic supports Al{sub 2}O{sub 3}, La{sub 2}O{sub 3} and Al{sub 2}O{sub 3}-La{sub 2}O{sub 3} were prepared by the Precipitation and Coprecipitation techniques. The catalytic supports Al{sub 2}O{sub 3}, La{sub 2}O{sub 3} and Al{sub 2}O{sub 3}-La{sub 2}O{sub 3} were characterized by several techniques to determine: texture (Bet), crystallinity (XRD), chemical composition (Sem)(Ftir) and it was evaluated their total acidity by reaction with 2-propanol. The investigation will be continued with the cobalt addition and this will be evaluated for its catalytic activity in control reactions of N O and N{sub 2}O. (Author)

  3. Synthesis, characterization of amine-bridged bis (phenolate) yttrium alkyl complex and its catalytic behavior for the Tishchenko reaction

    Institute of Scientific and Technical Information of China (English)

    PANG MingLun; YAO YingMing; ZHANG Yong; SHEN Qi

    2008-01-01

    Reaction of homoleptic yttrium tris-alkyl complex YR3 (R=CH2C3H4NMe2-o) with 1 equivalent of amine bis(phenol)s LH2 (L=Me2NCH2CH2N(CH2-(2-O-C6H2-Butt2-3,5))2) afforded the solvent-free yttrium alkyl complex LYR (1), which has been characterized with elemental analysis, 1H NMR and IR spectra, and structural determination. The coordination geometry around the center metal atom can be best de-scribed as a distorted octahedron. It was found that complex 1 can be used as an efficient catalyst for the Tishchenko reaction.

  4. Composite polymer/oxide hollow fiber contactors: versatile and scalable flow reactors for heterogeneous catalytic reactions in organic synthesis.

    Science.gov (United States)

    Moschetta, Eric G; Negretti, Solymar; Chepiga, Kathryn M; Brunelli, Nicholas A; Labreche, Ying; Feng, Yan; Rezaei, Fateme; Lively, Ryan P; Koros, William J; Davies, Huw M L; Jones, Christopher W

    2015-05-26

    Flexible composite polymer/oxide hollow fibers are used as flow reactors for heterogeneously catalyzed reactions in organic synthesis. The fiber synthesis allows for a variety of supported catalysts to be embedded in the walls of the fibers, thus leading to a diverse set of reactions that can be catalyzed in flow. Additionally, the fiber synthesis is scalable (e.g. several reactor beds containing many fibers in a module may be used) and thus they could potentially be used for the large-scale production of organic compounds. Incorporating heterogeneous catalysts in the walls of the fibers presents an alternative to a traditional packed-bed reactor and avoids large pressure drops, which is a crucial challenge when employing microreactors. PMID:25865826

  5. Synthesis and Catalytic Activity of a Two-core Ruthenium Carbene Complex: a Unique Catalyst for Ring Closing Metathesis Reaction

    Institute of Scientific and Technical Information of China (English)

    SHAO Ming-bo; WANG Jian-hui

    2011-01-01

    The reaction of a ruthenium carbide complex RuCl2(C:)(PCy3)2 with [H(Et2O)x]+[BF4]- at a molar ratio of 1:2 produced a two-core ruthenium carbene complex,{[RuCl(=HPCy3)(PCy3)]2(μ-Cl)3}+[BF4]-,in the form of a yellow-green crystalline solid in a yield of 94%.This two-core ruthenium complex is a selective catalyst for ring closing metathesis of unsubstituted terminal dienes.More importantly,no isomerized byproduct was observed for N-substrates when the two-core ruthenium complex was used as the catalyst at an elevated temperature(137 ℃),indicating that the complex is a chemo-selective catalyst for ring closing metathesis reactions.

  6. An Environmentally-Friendly and Catalytic Procedure for Mukaiyama Aldol Reaction Using Organic Catalyst DBU under Solvent Free Conditions

    Institute of Scientific and Technical Information of China (English)

    SHEN,Zhi-Liang; JI,Shun-Jun; LOH,Teck Peng

    2004-01-01

    @@ Recently, methods based exclusively on organic catalysts have become of major significance in synthetic chemistry.Mukaiyama-aldol reaction, as one of the most important and frequently utilized methods for C-C bond formation, is well documented in literatures recently. A variety of reagents, particularly metal-containing Lewis acids or bases, are known to promote the nucleophilic process. However, many of the reported strategies might have the following limitations from environmental viewpoints: (1) the use of metal-containing catalyst. Some of the catalysts are air or moisture sensitive (such as lithium amide), and crucial reaction conditions are needed; Some of the catalysts derived from poisonous metal (for example: SnCl4, SmI2 etc.) may cause harmful influence on humane body and environment; (2) the use of organic solvent (such as DMF, CH2Cl2 etc.) may bring about environmental pollution and solvent waste.

  7. 催化裂化提升管反应器中颗粒聚团裂化反应的数值模拟%Numerical Predication of Cracking Reaction of Particle Clusters in Fluid Catalytic Cracking Riser Reactors

    Institute of Scientific and Technical Information of China (English)

    王淑彦; 陆慧林; 高金森; 徐春明; 孙丹

    2008-01-01

    Behavior of catalytic cracking reactions of particle cluster in fluid catalytic cracking(FCC)riser reac-tors was numerically analyzed using a four-lump mathematical model.Effects of the cluster porosity.inlet gas ve-locity and temperature,and coke deposition on cracking reactions of the cluster were investigated. Distributions of temperature,gases,and gasoline from both catalyst particle cluster and an isolated catalyst particle are presented.The reaction rates from vacuum gas oil(VGO)to gasoline,gas and coke of individual particle in the cluster arehigher than those of the isolated particle,but it reverses for the reaction rates from gasoline to gas and coke.Less gasoline is produccd bv particle clustering.Simulated results show that the produced mass fluxes of gas and gasolineincrease with the operating temperature and molar concentration of VGO,and decrease due to the formation of coke.

  8. PVA降解酶催化反应的动力学方程%Kinetic Equation on the Catalytic Reaction of PVA-Degradation Enzyme

    Institute of Scientific and Technical Information of China (English)

    郭雅妮; 段士然; 周明; 崔双科

    2012-01-01

    The properties and catalytic reaction kinetics of PVA-degradation enzyme from a newly selected mixed strain that is able to fully degrade PVA were studied for its actual use. Through the determination of changes in enzymatic activities in the course of the PVA degradation process, a catalysis kinetic equation was assumed first and then verified. The results indicated that the enzymatic activities would get lower along with the PVA degradation efficiency rising when PVA was not yet completely degraded. After the degradation was completed, the enzymatic activities tended to keep at certain level. As the PVA concentration increased, the enzymatic activities enhanced gradually. Michaelis constant Kr, of PVA-degradation enzyme was 2.06×10^-3 mol/L and the highest reaction rate Vr~,x was 19.5 units per minute. Thus, the kinetic equation on the catalytic reaction could be obtained as V=19.5 [S] / (2.06×10^-3+[S]).%筛选了1种能够完全降解PVA的混合菌系,对其所生产的PVA降解酶的降解性质及其酶催化反应动力学进行了研究。通过测定在PVA降解过程中酶活的变化,采用"先假设-后验证"的方法研究酶催化动力学方程。结果表明,在PVA未完全降解时,该降解酶的酶活随着PVA降解效率的提高而降低;在完全降解后,其酶活趋于一定。随着PVA浓度的升高,酶活逐渐提高。该酶的米氏常数Km=2.06×10^-3mol/L,最大反应速率Vmax=19.5U/min,得到该酶对PVA的催化反应动力学方程,为V=19.5[S]/(2.06×10^-3+[S]),从而为混合菌系的实际应用提供理论依据。

  9. Qualitative Aspects of the Solutions of a Mathematical Model for the Dynamic Analysis of the Reversible Chemical Reaction SO2(g)+1/2O2(g)<=>SO3(g) in a Catalytic Reactor

    CERN Document Server

    Wilfredo, Angulo

    2014-01-01

    We present some qualitative aspects concerning the solution to the mathematical model describing the dynamical behavior of the reversible chemical reaction SO2(g)+1/2O2(g)SO3(g) carried out in a catalytic reactor used in the process of sulfuric acid production.

  10. Interaction Induced High Catalytic Activities of CoO Nanoparticles Grown on Nitrogen-Doped Hollow Graphene Microspheres for Oxygen Reduction and Evolution Reactions

    Science.gov (United States)

    Jiang, Zhong-Jie; Jiang, Zhongqing

    2016-06-01

    Nitrogen doped graphene hollow microspheres (NGHSs) have been used as the supports for the growth of the CoO nanoparticles. The nitrogen doped structure favors the nucleation and growth of the CoO nanoparticles and the CoO nanoparticles are mostly anchored on the quaternary nitrogen doped sites of the NGHSs with good monodispersity since the higher electron density of the quaternary nitrogen favors the nucleation and growth of the CoO nanoparticles through its coordination and electrostatic interactions with the Co2+ ions. The resulting NGHSs supported CoO nanoparticles (CoO/NGHSs) are highly active for the oxygen reduction reaction (ORR) with activity and stability higher than the Pt/C and for the oxygen evolution reaction (OER) with activity and stability comparable to the most efficient catalysts reported to date. This indicates that the CoO/NGHSs could be used as efficient bi-functional catalysts for ORR and OER. Systematic analysis shows that the superior catalytic activities of the CoO/NGHSs for ORR and OER mainly originate from the nitrogen doped structure of the NGHSs, the small size of the CoO nanoparticles, the higher specific and electroactive surface area of the CoO/NGHSs, the good electric conductivity of the CoO/NGHSs, the strong interaction between the CoO nanoparticles and the NGHSs, etc.

  11. Supramolecular Macrocyclic Pd(II) and Pt(II) Squares and Rectangles with Aryldithiolate Ligands and their Excellent Catalytic Activity in Suzuki C-C Coupling Reaction.

    Science.gov (United States)

    Vivekananda, K V; Dey, S; Maity, D K; Bhuvanesh, N; Jain, V K

    2015-11-01

    Addition of 1,4-benezenedithiol and 4,4'-biphenyldithiol to M(OTf)2 (M = cis-[Pt(PEt3)2](2+) or cis-[Pd(dppe)](2+)) (dppe = 1,2-bis(diphenylphosphino)ethane) gave self-assembled tetranuclear complexes [M2{S(C6H4)nS}]2(OTf)4 (n = 1, 2). The same reaction with 1,4-benezenedimethanethiol yielded octanuclear supramolecular coordination complexes (SCC) [M2{SCH2C6H4CH2S}]4(OTf)8. These complexes were characterized by NMR, mass, and UV-vis spectroscopies, cyclic voltammetry, as well as density functional theory studies and represent the first examples of SCCs constructed by thiolate groups and square-planar metal ions. The rectangular shape of tetranuclear complexes and square shape of octanuclear complex are confirmed by single-crystal structures and computational studies. The palladium complexes showed excellent catalytic activity in Suzuki C-C cross-coupling reactions with high turnover numbers (2 × 10(7)), even with low catalyst loading. PMID:26444245

  12. Interaction Induced High Catalytic Activities of CoO Nanoparticles Grown on Nitrogen-Doped Hollow Graphene Microspheres for Oxygen Reduction and Evolution Reactions.

    Science.gov (United States)

    Jiang, Zhong-Jie; Jiang, Zhongqing

    2016-01-01

    Nitrogen doped graphene hollow microspheres (NGHSs) have been used as the supports for the growth of the CoO nanoparticles. The nitrogen doped structure favors the nucleation and growth of the CoO nanoparticles and the CoO nanoparticles are mostly anchored on the quaternary nitrogen doped sites of the NGHSs with good monodispersity since the higher electron density of the quaternary nitrogen favors the nucleation and growth of the CoO nanoparticles through its coordination and electrostatic interactions with the Co(2+) ions. The resulting NGHSs supported CoO nanoparticles (CoO/NGHSs) are highly active for the oxygen reduction reaction (ORR) with activity and stability higher than the Pt/C and for the oxygen evolution reaction (OER) with activity and stability comparable to the most efficient catalysts reported to date. This indicates that the CoO/NGHSs could be used as efficient bi-functional catalysts for ORR and OER. Systematic analysis shows that the superior catalytic activities of the CoO/NGHSs for ORR and OER mainly originate from the nitrogen doped structure of the NGHSs, the small size of the CoO nanoparticles, the higher specific and electroactive surface area of the CoO/NGHSs, the good electric conductivity of the CoO/NGHSs, the strong interaction between the CoO nanoparticles and the NGHSs, etc. PMID:27255562

  13. Developments in catalytic asymmetric Strecker reaction of aldimines%醛亚胺的不对称Strecker反应研究进展

    Institute of Scientific and Technical Information of China (English)

    唐贝; 李高伟

    2013-01-01

    α-Aminonitriles can be easily converted to α-amino acids, and is an important intermediate for the synthesis of many biologically active natural products and drugs. The asymmetric Strecker reaction of the aldimine as a direct and affective method of synthesis of optically active α-aminonitriles has been widely accepted. In this current paper, the developments in catalytic asymmetric Strecker reaction of aldimines is introduced.%α-氨基腈不仅可以很容易地转化为α-氨基酸,而且是合成许多具有生物活性的天然产物和药物的重要中间体.醛亚胺的不对称Strecker反应作为制备光学活性α-氨基腈的直接而有效的方法之一,已被广泛接受.作者介绍了醛亚胺的不对称Strecker反应研究进展.

  14. Effects of N{sub 2}O gas addition on the properties of ZnO films grown by catalytic reaction-assisted chemical vapor deposition

    Energy Technology Data Exchange (ETDEWEB)

    Yasui, Kanji, E-mail: kyasui@vos.nagaokaut.ac.jp; Morioka, Makoto; Kanauchi, Shingo; Ohashi, Yuki; Kato, Takahiro; Tamayama, Yasuhiro [Department of Electrical, Electronic, and Information Engineering, Nagaoka University of Technology, 1603-1 Kamitomioka, Nagaoka, Niigata 940-2188 (Japan)

    2015-11-15

    The influence of N{sub 2}O gas addition on the properties of zinc oxide (ZnO) films grown on a-plane (11–20) sapphire (a-Al{sub 2}O{sub 3}) substrates was investigated, using a chemical vapor deposition method based on the reaction between dimethylzinc and high-temperature H{sub 2}O produced by a catalytic H{sub 2}-O{sub 2} reaction on platinum (Pt) nanoparticles. The addition of N{sub 2}O was found to increase the size of the crystalline facets and to improve the crystal orientation along the c-axis. The electron mobility at 290 K was also increased to 234 cm{sup 2}/Vs following the addition of N{sub 2}O gas at a pressure of 3.2 × 10{sup −3 }Pa. In addition, the minimum full width at half maximum of the most intense photoluminescence peak derived from neutral donor bound excitons at 10 K decreased to 0.6 meV by the addition of N{sub 2}O gas at a pressure of 3.1 × 10{sup −2 }Pa.

  15. 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)

  16. Catalytic Combustion of Ethyl Acetate

    OpenAIRE

    ÖZÇELİK, Tuğba GÜRMEN; ATALAY, Süheyda; ALPAY, Erden

    2007-01-01

    The catalytic combustion of ethyl acetate over prepared metal oxide catalysts was investigated. CeO, Co2O3, Mn2O3, Cr2O3, and CeO-Co2O3 catalysts were prepared on monolith supports and they were tested. Before conducting the catalyst experiments, we searched for the homogeneous gas phase combustion reaction of ethyl acetate. According to the homogeneous phase experimental results, 45% of ethyl acetate was converted at the maximum reactor temperature tested (350 °C). All the prepare...

  17. Solvent-Free Wittig Reaction: A Green Organic Chemistry Laboratory Experiment

    Science.gov (United States)

    Leung, Sam H.; Angel, Stephen A.

    2004-01-01

    Some Wittig reactions can be carried out by grinding the reactants in a mortar with a pestle for about 20 minutes, as per investigation. A laboratory experiment involving a solvent-free Wittig reaction that can be completed in a three-hour sophomore organic chemistry laboratory class period, are developed.

  18. Discrimination of Inner- and Outer-Sphere Electrode Reactions by Cyclic Voltammetry Experiments

    Science.gov (United States)

    Tanimoto, Sachiko; Ichimura, Akio

    2013-01-01

    A laboratory experiment for undergraduate students who are studying homogeneous and heterogeneous electron-transfer reactions is described. Heterogeneous or electrode reaction kinetics can be examined by using the electrochemical reduction of three Fe[superscript III]/Fe[superscript II] redox couples at platinum and glassy carbon disk electrodes.…

  19. Fundamental studies of the mechanism of catalytic reactions with catalysts effective in the gasification of carbon solids and the oxidative coupling of methane. Quarterly report, January 1, 1995--March 31, 1995

    Energy Technology Data Exchange (ETDEWEB)

    Iglesia, E.; Perry, D.L.; Heinemann, H.

    1995-03-01

    The synthesis of ethane and ethylene from methane and oxygen will be carried out in novel hydrogen transport inorganic membranes and in cyclic reactors in order to prevent undesirable secondary reactions of C{sub 2} molecules to CO and CO{sub 2}. Neither inorganic membrane reactors nor cyclic tubular reactors are presently used in commercial processes. Their application to catalytic reactions represents a novel application of engineering and solid-state chemistry concepts to catalytic reactions. Our approach combines high temperature membrane and cyclic experimental reactors, synthesis and characterization of thin membrane films and of high surface area catalysts, and detailed models of complex gas phase and surface reactions involved in oxidative coupling. We anticipate that this approach will lead to novel reactors for carrying our kinetic-controlled sequential reactions, such as the oxidative coupling of methane. Careful spectrographic and wet chemical analyses of fresh and silent catalysts have shown considerable differences which have permitted conclusions as to the source of deactivation. Our activities in the first quarter FYI 995 have focused on the synthesis, structural characterization, and catalytic evaluation of membrane films, disks, and reactors. We have also continued to exploit reaction-transport models to predict the performance of membrane, cyclic, and recycle reactors in the oxidative coupling of methane.

  20. Modification of the adsorption and catalytic properties of micro-and mesoporous materials by reactions with organometallic complexes

    Institute of Scientific and Technical Information of China (English)

    LEFEBVRE; Frédéric; PUTAJ; Piotr; BASSET; Jean-Marie

    2010-01-01

    This review describes the work of two laboratories in the field of the modification of micro-and mesoporous molecular sieves through reactions with organometallic complexes.The modification of zeolites can occur inside the pore channels or on the external surface,depending on the size of the organometallic complex.When the modification occurs on the external surface,it results in a decrease of the pore entrance,which will lead in turn to a modification of the sorption properties of the zeolite,by decreasing the rate of the adsorption(mainly by a kinetic control).Such a material can be also used in catalysis,because the external acid sites,which are responsible for side-reactions,have been removed upon grafting.When small organometallic complexes are used,they can fill the channels and cages of the zeolite and react with internal hydroxyl groups.Due to the high acidity of zeolites,the reaction occurs very easily(for example at-100℃ on faujasite),in contrast to what is observed on the external surface,therefore leading to high metal loadings.In that case,the modification of the sorption properties will be mainly related to a thermodynamic control.The resulting materials can be useful in catalysis,by combining the activity of the organometallic complex and properties(for example shape-selectivity) of the zeolite.Modification of mesoporous molecular sieves occurs always in the pores and results in altering of the sorption properties of the solid,by changing the interaction type between the sorbent and the sorbate.For example the sorption isotherm of alkanes is changed from type II to type III according to the IUPAC nomenclature.

  1. Insight into the Catalytic Mechanism of Bimetallic Platinum-Copper Core-Shell Nanostructures for Nonaqueous Oxygen Evolution Reactions.

    Science.gov (United States)

    Ma, Lu; Luo, Xiangyi; Kropf, A Jeremy; Wen, Jianguo; Wang, Xiaoping; Lee, Sungsik; Myers, Deborah J; Miller, Dean; Wu, Tianpin; Lu, Jun; Amine, Khalil

    2016-01-13

    The oxygen evolution reaction (OER) plays a critical role in multiple energy conversion and storage applications. However, its sluggish kinetics usually results in large voltage polarization and unnecessary energy loss. Therefore, designing efficient catalysts that could facilitate this process has become an emerging topic. Here, we present a unique Pt-Cu core-shell nanostructure for catalyzing the nonaqueous OER. The catalysts were systematically investigated with comprehensive spectroscopic techniques, and applied in nonaqueous Li-O2 electrochemical cells, which exhibited dramatically reduced charging overpotential (OER catalysts. PMID:26709945

  2. The Barium Hydroxide-Ammonium Thiocyanate Reaction: A Titrimetric Continuous Variations Experiment.

    Science.gov (United States)

    Harris, Arlo D.

    1979-01-01

    Presents an experiment for inorganic, organic, or physical chemistry students utilizing acid-base titrimetry to study the stoichiometric of a solid state reaction. Time involved ranges from one to three, three-hour lab periods. (Author/SA)

  3. 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

  4. Reaction Wheel Friction Telemetry Data Processing Methodology and On-Orbit Experience

    Science.gov (United States)

    Hacker, Johannes M.; Ying, Jiongyu; Lai, Peter C.

    2015-09-01

    A Globalstar 2nd generation satellite experienced a reaction wheel mechanical failure, and in response Globalstar has been closely monitoring reaction wheel bearing friction. To prevent another reaction wheel hardware failure and subsequent shortened satellite mission life, a friction data processing methodology was developed as an on-orbit monitoring tool for the ground to issue early warning and take appropriate action on any hardware degradation or potential failure. The methodology, reaction wheel friction behavior, and its application to an on-orbit anomaly experience will be presented.

  5. INTERF: the reaction rates and spectra editing code for analysis of fusion neutronics experiments

    International Nuclear Information System (INIS)

    The reaction rates and spectra editing code INTERF has been developed for transport calculation codes as a part of the analysis system for fusion neutronics experiments. This code can provide the ratio of calculation to experiment value for reaction rate (C/E), spectra, reaction rate distributions, contour distributions, etc. from results of transport calculation. The transport calculation codes that INTERF can process are the ANISN, DOT3.5, BERMUDA-2DN, MCNP and MORSE-DD codes. In this report, the concept, functions, input data, and input/output files in INTERF are described and the examples of input data for usage of INTERF are shown. (author)

  6. Study of the structure of unstable nuclei through the reaction experiments

    Institute of Scientific and Technical Information of China (English)

    2011-01-01

    Along with the development of the radioactive nuclear beam facility, the study of the structure of unstable nuclei has progressed rapidly over the last few decades. Due to the weakly binding property, the structure information of the unstable nuclei comes primarily from the scattering or reaction experiments. Therefore it would be very important to understand clearly the reaction mechanism involved in the experiment. We outlined here the major reaction mechanisms which are adequate to the study of unstable nuclei, with the focus on the new phenomena and methods in comparison with those with traditional stable nucleus beam. Especially emphasized are the breakup and knockout reactions, developed as accurate tools for spectroscopy investigation into the nuclear structure with low intensity secondary beam. Couplings of the breakup channel to the elastic scattering and the fusion and transfer reactions are also reviewed.

  7. Resonance threshold singularities in reaction cross sections and the full experiment problem

    International Nuclear Information System (INIS)

    The full experiment problem near the resonance threshold is considered. The following conclusions are made. In case of spinless particles the measurement of the differential cross section energy dependence in all open channels i, r (where i is an input reaction channel, r is a nonthreshold reaction channel, including r=i) near the (i, q) reaction threshold (where q is a threshold reaction channel) permits to perform a full phase analysis in the channels i, r in the near-threshold region and determine the (i, q) reaction cross section. The analysis of threshold anomalies in the integral cross sections permits to determine the resonance matrix elements. The results obtained can be used for the a+X → b+Y → b+c+d type reaction with two-step decay via an intermediate nucleus Y

  8. Experiments and reaction characteristics of liquid phase simultaneous removal of SO2 and NO

    Institute of Scientific and Technical Information of China (English)

    LIU Feng; GUO TianXiang; ZHAO Yin

    2009-01-01

    Experiments of simultaneous removal of SO2 and NO from simulated flue gas, using NaClO2 solution as the absorbent, were carried out in a self-designed bubble reactor, and high simultaneous removal effi-cienciee of SO2 and NO were obtained under the optimal experimental conditions. The mechanism of simultaneous removal based on NaClO2 acid solutions was proposed by analyzing the removal prod-ucts. Possibility and limitation of the desulfurization and denitrification using NaClO2 acid solutions were calculated by thermodynamic methods. Experimental results of reaction kinetics for simultaneous desulfurization and denitrification indicated that the oxidation-absorption processes of SO2 and NO were divided into two zones, namely the fast and slow reaction zones. In the slow reaction zones both were zero order reactions, and in the fast reaction zones, the reaction order, rate constant and activa-

  9. Activation of Aryl Halides by Nickel(I) Pincer Complexes: Reaction Pathways of Stoichiometric and Catalytic Dehalogenations.

    Science.gov (United States)

    Rettenmeier, Christoph A; Wenz, Jan; Wadepohl, Hubert; Gade, Lutz H

    2016-08-15

    Homolytic C-X bond cleavage of organohalides by the T-shaped nickel(I) complexes [LigNi(I)] 1 bearing the iso-PyrrMeBox ligand had been found previously to be the crucial activation step in the asymmetric hydrodehalogenation of geminal dihalides. Here, this mechanistic investigation is extended to aryl halides, which allowed a systematic study of the activation process by a combination of experimental data and density functional theory modeling. While the activation of both aryl chlorides and geminal dichlorides appears to proceed via an analogous transition state, the generation of a highly stabile nickel(II)aryl species in the reaction of the aryl chlorides for the former represents a major difference in the reactive behavior. This difference was found to have a crucial impact on the activity of these nickel pincer systems as catalysts in the dehalogenation of aryl chlorides compared to geminal dichlorides and highlights the importance of the regulatory pathways controlling the nickel(I) concentration throughout the catalysis. These results along with the identification and characterization of novel nickel(II)aryl species are presented. PMID:27483018

  10. Tin-silicalite-1: Synthesis by dry gel conversion, characterization and catalytic performance in phenol hydroxylation reaction

    International Nuclear Information System (INIS)

    Tin-silicalite-1 (Sn-MFI) has been successfully synthesized by dry gel conversion (DGC) method. The influence of various synthesis parameters such as crystallization time, temperature, water content at the bottom of autoclave, molar ratios of (TPA)2O/SiO2 and SiO2/SnO2 in dry gel on the crystallization kinetics and physico-chemical properties of Sn-MFI materials has been investigated. Powder-X-ray diffraction (XRD), XPS, AAS, DRUV-vis and SEM techniques were employed as characterization tools. Time-dependent studies revealed that, the progressive crystallization of Sn-MFI depend not only on the synthesis time but also on the other various synthesis parameters. Increase in the crystallization temperature, water content at bottom of autoclave (TPA)2O/SiO2 and SiO2/SnO2 molar ratios in dry gel resulted in the lowering of overall crystallization period. A good correspondence between the chemical composition of the surface and the bulk indicated the uniform distribution of Sn4+ ions. The presence of these ions in tetrahedral coordination has been indicated by DRUV-vis spectral studies. Although, not better but comparable activity has been shown by Sn-MFI prepared by dry gel conversion method with Sn-MFI prepared by conventional hydrothermal crystallization method in the hydroxylation of phenol reaction. Increase in concentration of isolated Sn4+ ions led to increase in phenol conversion and H2O2 efficiency

  11. Recent development in catalytic oxidation reactions in the homogeneous phase; Recenti sviluppi nelle reazioni di ossidazioni catalitica in fase omogenea

    Energy Technology Data Exchange (ETDEWEB)

    Strukul, G. [Venice Univ., Venice (Italy). Dipt. di Chimica

    2000-10-01

    The present review summarizes the works presented at the recent National Conference of SCI (SCI 2000) during a minisimposium with the same title. The arguments dealt encompass a wide range and provide a rather exhausting overview of the national activities in this area. The topics considered are: the synthesis of hydrogen peroxide, the modified Fenton systems for the synthesis of phenol, the use of ruthenium complexes in the enantioselective epoxidation of olefins, the stereoselective, sulfoxidations mediated by titanium and zirconium complexes, the oxidation of organics in water catalyzed by metallo-phthalocyanins, the use of ketones as catalysts in the selective oxidation with potassium caroate, the oxidation of natural organic substrates catalyzed by metalloporphyrins, some new hybrid catalysts for oxidation reactions with hydrogen peroxide. [Italian] La presente rassegna riassume i lavori presentati al recente congresso nazionale della SCI (SCI 2000) durante un minisimposio avente lo stesso titolo. I temi trattati abbracciano un ventaglio piuttosto ampio e forniscono uno spaccato abbastanza esauriente della ricerca nazionale in questo settore. Gli argomenti descritti sono: la sintesi dell'acqua ossigenata, i sistemi di Fenton modificati per la sintesi del fenolo, l'uso dei complessi di rutenio nell'epossidazione enantioselettiva di olefine, le solfossidazioni stereoselettive mediate da complessi di titanio e zirconio, l'ossidazione di substrati organici in ambiente acquoso catalizzata da metallo-ftalocianine, la catalisi da chetoni nell'ossidazione selettiva con caroato di potassio, l'ossidazione di substrati organici naturali catalizzata da metallo-porfirine, alcuni nuovi catalizzatori ibridi per reazioni di ossidazione con acqua ossigenata.

  12. Tin-silicalite-1: Synthesis by dry gel conversion, characterization and catalytic performance in phenol hydroxylation reaction

    Energy Technology Data Exchange (ETDEWEB)

    Niphadkar, Prashant S.; Kotwal, Mehejabeen S.; Deshpande, Shilpa S.; Bokade, Vijay V. [Catalysis Division, National Chemical Laboratory, Pune 411008 (India); Joshi, Praphulla N. [Catalysis Division, National Chemical Laboratory, Pune 411008 (India)], E-mail: pn.joshi@ncl.res.in

    2009-03-15

    Tin-silicalite-1 (Sn-MFI) has been successfully synthesized by dry gel conversion (DGC) method. The influence of various synthesis parameters such as crystallization time, temperature, water content at the bottom of autoclave, molar ratios of (TPA){sub 2}O/SiO{sub 2} and SiO{sub 2}/SnO{sub 2} in dry gel on the crystallization kinetics and physico-chemical properties of Sn-MFI materials has been investigated. Powder-X-ray diffraction (XRD), XPS, AAS, DRUV-vis and SEM techniques were employed as characterization tools. Time-dependent studies revealed that, the progressive crystallization of Sn-MFI depend not only on the synthesis time but also on the other various synthesis parameters. Increase in the crystallization temperature, water content at bottom of autoclave (TPA){sub 2}O/SiO{sub 2} and SiO{sub 2}/SnO{sub 2} molar ratios in dry gel resulted in the lowering of overall crystallization period. A good correspondence between the chemical composition of the surface and the bulk indicated the uniform distribution of Sn{sup 4+} ions. The presence of these ions in tetrahedral coordination has been indicated by DRUV-vis spectral studies. Although, not better but comparable activity has been shown by Sn-MFI prepared by dry gel conversion method with Sn-MFI prepared by conventional hydrothermal crystallization method in the hydroxylation of phenol reaction. Increase in concentration of isolated Sn{sup 4+} ions led to increase in phenol conversion and H{sub 2}O{sub 2} efficiency.

  13. Kinetic modelling of hydrocracking catalytic reactions by the single events theory; Modelisation cinetique des reactions catalytiques d`hydrocraquage par la theorie des evenements constitutifs

    Energy Technology Data Exchange (ETDEWEB)

    Schweitzer, J.M.

    1998-11-23

    Kinetic modelling of petroleum hydrocracking is particularly difficult given the complexity of the feedstocks. There are two distinct classes of kinetics models: lumped empirical models and detailed molecular models. The productivity of lumped empirical models is generally not very accurate, and the number of kinetic parameters increases rapidly with the number of lumps. A promising new methodology is the use of kinetic modelling based on the single events theory. Due to the molecular approach, a finite and limited number of kinetic parameters can describe the kinetic behaviour of the hydrocracking of heavy feedstock. The parameters are independent of the feedstock. However, the available analytical methods are not able to identify the products on the molecular level. This can be accounted for by means of an posteriori lamping technique, which incorporates the detailed knowledge of the elementary step network. Thus, the lumped kinetic parameters are directly calculated from the fundamental kinetic coefficients and the single event model is reduced to a re-lumped molecular model. Until now, the ability of the method to extrapolate to higher carbon numbers had not been demonstrated. In addition, no study had been published for three phase (gas-liquid-solid) systems and a complex feedstock. The objective of this work is to validate the `single events` method using a paraffinic feedstock. First of all, a series of experiments was conducted on a model compound (hexadecane) in order to estimate the fundamental kinetic parameters for acyclic molecules. To validate the single event approach, these estimated kinetic coefficients were used to simulate hydrocracking of a paraffinic mixture ranging from C11 to C18. The simulation results were then compared to the results obtained from the hydrocracking experiments. The comparison allowed to validate the model for acyclic molecules and to demonstrate that the model is applicable to compounds with higher carbon numbers. (author

  14. New insights in understanding plasma-catalysis reaction pathways: study of the catalytic ozonation of an acetaldehyde saturated Ag/TiO2/SiO2 catalyst

    Science.gov (United States)

    Sauce, Sonia; Vega-González, Arlette; Jia, Zixian; Touchard, Sylvain; Hassouni, Khaled; Kanaev, Andrei; Duten, Xavier

    2015-07-01

    This paper is a preliminary study intended to straighten out the role of reactive oxygen species in the activation mechanisms occurring in a plasma driven catalysis process for acetaldehyde decomposition. For this purpose, the interaction between the surface, the pollutant and one of the main oxidative species generated by non-thermal plasma, namely ozone, was studied. Acetaldehyde catalytic ozonation over a nanostructured Ag/TiO2/SiO2 catalyst is carried out at room temperature and atmospheric pressure, and followed by diffuse reflectance infrared fourier transform spectroscopy (DRIFTS). For this, the catalyst is firstly saturated with acetaldehyde. At the end of the saturation, acetaldehyde and crotonaldehyde, its condensation product, are identified as the major adsorbed species. In a second step, the surface ozonation is carried out and three additional intermediates are identified, namely, acetone, formic acid and acetic acid. Gaseous CO, CO2, methyl formate and methyl acetate are detected at the DRIFTS outlet, evidencing the partial mineralization of the adsorbed species. A global reaction scheme is proposed for explaining the formation of those adsorbed intermediates and gaseous products. This proposed heterogeneous ozone induced chemistry has to be taken into account when associating non-thermal plasma in air to a catalyst. Contribution to the topical issue "The 14th International Symposium on High Pressure Low Temperature Plasma Chemistry (HAKONE XIV)", edited by Nicolas Gherardi, Ronny Brandenburg and Lars Stollenwark

  15. 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.

  16. Fe-N-C electrocatalysts for oxygen reduction reaction synthesized by using aniline salt and Fe3+/H2O2 catalytic system

    KAUST Repository

    Bukola, Saheed

    2014-11-01

    Non-precious metal (NPM) catalysts are synthesized by polymerizing aniline salt using an aqueous Fe3+/H2O2 coupled catalytic system on a carbon matrix with a porous creating agent. The sulfur containing compunds such as ammonium peroxydisulfate, are eliminated in this method resulting in a much simpler process. The catalysts\\' porous structures are enhanced with ammonium carbonate as a sacrificial material that yields voids when decomposed during the heat treatment at 900 °C in N2 atmosphere. Two catalysts Fe-N-C/Vu and Fe-N-C/KB (Vu = Vulcan and KB = Ketjen black) were synthesized and characterized. Their oxygen reduction reaction (ORR) activities were investigated using a rotating ring-disk electrode (RRDE) in both 0.1 M KOH and 0.1 M HClO4. The catalysts show improved ORR activities close to that of Pt-based catalysts, low H2O2 formation and also demonstrated a remarkable tolerance towards methanol oxidation.

  17. Design Of A Simple Apparatus For Reaction Kinetics And Reactor Design Experiments

    OpenAIRE

    Vavanellos, T. D.

    1990-01-01

    Tubular reactor experiments arc an integral part of an undergraduate course in reaction kinetics and reactor design. However, the successful design of such experiments necessitates meeting a set of criteria regarding safety, simplicity of design and aniytical needs, acceptable cost, and instuctional value. The design of a tubular reactor experiment satisfying the above criteria is presented here. It is hoped that this design can serve as the basis for assembling the necessary experimental app...

  18. Medical Students’ Experience of and Reaction to Stress: The Role of Depression and Anxiety

    Directory of Open Access Journals (Sweden)

    Coumaravelou Saravanan

    2014-01-01

    Full Text Available Background. Medical school is recognized as a stressful environment that often has a negative effect on students’ academic performance, physical health, and psychosocial well-being. Previous studies have not identified differences between depressed and nondepressed and anxious and nonanxious medical students’ experiences of stress or their reactions to stressors. The present study aimed to identify the prevalence of depression and anxiety among a sample of 358 medical students attending a private university in Malaysia and to examine differences according to participants’ gender, year of study, and stage of training (preclinical and clinical. Additionally, this study examined the extent to which stress predicts depression and anxiety, differences between depressed and nondepressed medical students’ experiences of and reactions to stressors, and differences between anxious and nonanxious medical students’ experiences of and reactions to stressors. Methods. The Student Life Stress Inventory was used to measure stress and reaction to stressors and the Depression, Anxiety, and Stress Scale was used to measure depression and anxiety. Results. The results showed that 44% (n=158 of the students were anxious and 34.9% (n=125 were depressed. More female students exhibited anxiety compared to male students. Stress is a predictor for depression and anxiety. A significant difference was found between depressed and nondepressed and anxious and nonanxious students’ experience of stressors due to frustration, change, and their emotional reaction to stressors. Conclusion. Overall, depressed and anxious students were found to experience more stress and react differently to stressors compared to nondepressed and nonanxious students.

  19. The ReactorSTM: Atomically resolved scanning tunneling microscopy under high-pressure, high-temperature catalytic reaction conditions

    International Nuclear Information System (INIS)

    To enable atomic-scale observations of model catalysts under conditions approaching those used by the chemical industry, we have developed a second generation, high-pressure, high-temperature scanning tunneling microscope (STM): the ReactorSTM. It consists of a compact STM scanner, of which the tip extends into a 0.5 ml reactor flow-cell, that is housed in a ultra-high vacuum (UHV) system. The STM can be operated from UHV to 6 bars and from room temperature up to 600 K. A gas mixing and analysis system optimized for fast response times allows us to directly correlate the surface structure observed by STM with reactivity measurements from a mass spectrometer. The in situ STM experiments can be combined with ex situ UHV sample preparation and analysis techniques, including ion bombardment, thin film deposition, low-energy electron diffraction and x-ray photoelectron spectroscopy. The performance of the instrument is demonstrated by atomically resolved images of Au(111) and atom-row resolution on Pt(110), both under high-pressure and high-temperature conditions

  20. The ReactorSTM: Atomically resolved scanning tunneling microscopy under high-pressure, high-temperature catalytic reaction conditions

    Energy Technology Data Exchange (ETDEWEB)

    Herbschleb, C. T.; Tuijn, P. C. van der; Roobol, S. B.; Navarro, V.; Bakker, J. W.; Liu, Q.; Stoltz, D.; Cañas-Ventura, M. E.; Verdoes, G.; Spronsen, M. A. van; Bergman, M.; Crama, L.; Taminiau, I.; Frenken, J. W. M., E-mail: frenken@physics.leidenuniv.nl [Huygens-Kamerlingh Onnes Laboratory, Leiden University, P.O. box 9504, 2300 RA Leiden (Netherlands); Ofitserov, A.; Baarle, G. J. C. van [Leiden Probe Microscopy B.V., J.H. Oortweg 21, 2333 CH Leiden (Netherlands)

    2014-08-15

    To enable atomic-scale observations of model catalysts under conditions approaching those used by the chemical industry, we have developed a second generation, high-pressure, high-temperature scanning tunneling microscope (STM): the ReactorSTM. It consists of a compact STM scanner, of which the tip extends into a 0.5 ml reactor flow-cell, that is housed in a ultra-high vacuum (UHV) system. The STM can be operated from UHV to 6 bars and from room temperature up to 600 K. A gas mixing and analysis system optimized for fast response times allows us to directly correlate the surface structure observed by STM with reactivity measurements from a mass spectrometer. The in situ STM experiments can be combined with ex situ UHV sample preparation and analysis techniques, including ion bombardment, thin film deposition, low-energy electron diffraction and x-ray photoelectron spectroscopy. The performance of the instrument is demonstrated by atomically resolved images of Au(111) and atom-row resolution on Pt(110), both under high-pressure and high-temperature conditions.

  1. DEVELOPMENT OF HIGH ACTIVITY, CATALYTIC SYSTEMS FOR NOx REDUCTION

    Energy Technology Data Exchange (ETDEWEB)

    Unknown

    2001-12-01

    This project was directed at an investigation of catalytic NO{sub x} reduction on carbonaceous supports at low temperatures. The experimental work was conducted primarily in a packed bed reactor/gas flow system that was constructed for this work. The analytical techniques employed were mass spectrometry, NO{sub x} chemiluminescence, and gas chromatography. The experimental plan was focused on steady-state reactivity experiments, followed by temperature programmed desorption (TPD) of surface intermediates, and also selected temperature-programmed reaction (TPR) experiments. Both uncatalyzed and catalyzed (potassium-promoted) phenolic resin char, were investigated as well as the catalytic effect of additional CO in the gas phase.

  2. Radical-ion-pair reactions are the biochemical equivalent of the optical double-slit experiment.

    Science.gov (United States)

    Kominis, Iannis K

    2011-05-01

    Radical-ion-pair reactions were recently shown to represent a rich biophysical laboratory for the application of quantum measurement theory methods and concepts. Here we show that radical-ion-pair reactions essentially form a nonlinear biochemical double-slit interferometer. Quantum coherence effects are visible when "which-path" information is limited, and the incoherent limit is approached when measurement-induced decoherence sets in. Based on this analogy with the optical double-slit experiment we derive and elaborate on the fundamental master equation of spin-selective radical-ion-pair reactions that covers the continuous range from complete incoherence to maximum singlet-triplet coherence. PMID:21728616

  3. 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

  4. Experiments and reaction characteristics of liquid phase simultaneous removal of SO2 and NO

    Institute of Scientific and Technical Information of China (English)

    2009-01-01

    Experiments of simultaneous removal of SO2 and NO from simulated flue gas,using NaClO2 solution as the absorbent,were carried out in a self-designed bubble reactor,and high simultaneous removal effi-ciencies of SO2 and NO were obtained under the optimal experimental conditions.The mechanism of simultaneous removal based on NaClO2 acid solutions was proposed by analyzing the removal prod-ucts.Possibility and limitation of the desulfurization and denitrification using NaClO2 acid solutions were calculated by thermodynamic methods.Experimental results of reaction kinetics for simultaneous desulfurization and denitrification indicated that the oxidation-absorption processes of SO2 and NO were divided into two zones,namely the fast and slow reaction zones.In the slow reaction zones both were zero order reactions,and in the fast reaction zones,the reaction order,rate constant and activa-tion energy of SO2 reaction with absorbent were 1.4,1.22(mol.L-1)-0.4.s-1 and 66.25kJ.mol-1,respec-tively,and 2,3.15×103(mol.L-1)-1.s-1,and 42.50 kJ.mol-1 for NO reaction,respectively.

  5. Fundamental studies of the mechanism of catalytic reactions with catalysts effective in the gasification of carbon solids and the oxidative coupling of methane. Quarterly report, 1 January--31 March 1994

    Energy Technology Data Exchange (ETDEWEB)

    Iglesia, E.; Heinemann, H.; Perry, D.L. [Lawrence Berkeley Lab., CA (United States). Center for Advanced Materials

    1994-03-01

    This report describes work in progress on three tasks: (1) Catalytic steam gasification of coals and cokes; (2) Oxidative coupling of methane; and (3) Synthesis and characterization of catalysts. Since Task 1 is complete, a final report has been written. This report describes membrane reactors, cyclic methane conversion reactors, theoretical descriptions of reaction-separation schemes, and time-space relationships in cyclic and membrane reactors, all subtasks of Task 2. Initial studies under Task 3 are briefly described.

  6. Catalytic activity of Pt anchored onto graphite nanofiber-poly (3,4-ethylenedioxythiophene) composite toward oxygen reduction reaction in polymer electrolyte fuel cells

    International Nuclear Information System (INIS)

    Highlights: • GNF–PEDOT is explored as a catalyst support for PEFCs. • PEDOT bridges the Pt nanoparticles with GNF via π–π interaction. • Binding strength between Pt and GNF is improved and hence mitigates Pt aggregation. • GNF–PEDOT composite enhances ORR activity and durability in fuel cells. -- Abstract: The potential of graphite nanofiber (GNF)–Poly(3,4-ethylenedioxythiophene) (PEDOT) composite is explored as a catalyst support for polymer electrolyte fuel cells (PEFCs). Due to electron accepting nature of GNF and electron donating nature of PEDOT, the monomer EDOT adsorbs on the surface of GNF due to strong electrostatic π–π interaction. Pt nanoparticles are impregnated on GNF–PEDOT composite by ethylene glycol reduction method and their effects on electro catalytic activity for oxygen reduction reaction (ORR) are systemically studied. Pt particles supported on GNF–PEDOT with catalyst loading of 0.2 mg cm−2 exhibit a peak power density of 537 mW cm−2 at a load current density of 1120 mA cm−2, while it was only 338 mW cm−2 at a load current density of 720 mA cm−2 in case of Pt particles supported on pristine GNF. The superior behavior of GNF–PEDOT supported Pt catalyst could be exclusively credited to the high graphitic nature of GNF and their mild functionalization with PEDOT increasing uniform dispersion of Pt. Indeed, the non-destructive functionalization of GNF with conducting polymer, such as PEDOT, makes them promising catalyst-supports for PEFCs

  7. An ab initio study on the chemical reactions in the Cl-ClO catalytic cycle%Cl-ClO催化循环圈的从头算研究

    Institute of Scientific and Technical Information of China (English)

    毛连港; 邴单; 赵永芳; 李根全; 李新营; 蒿凤有; 刘凤丽

    2006-01-01

    One of processes of the ozone depletion in the polar stratosphere is investigated by using an ab initio calculation at the B3LYP/6-311+G (3df) and the G2 levels. The calculated result obviously supported the theory on destroying ozone mechanism of the Cl-ClO catalytic cycle, and explained basic reason of the destroying ozone from the energy point of view. The reactional energy, the enthalpy of formation, and relative Gibbs free energy of the reactions in the ClClO catalytic cycle are calculated exactly, and provided thermodynamics quantities for the reactions in the Cl-ClO catalytic cycle.%采用分子轨道从头算方法,在B3LYP/6-311+G(3df)和G2水平上研究了极地平流层臭氧损耗的一个基本过程.计算结果明显支持Cl-ClO催化循环圈机理,并且从能量角度解释了了臭氧破坏的基本原因.还对循环圈中各个反应的反应能,生成焓,相对吉布斯自由能做了计算,计算结果相互协调都说明了Cl-ClO催化循环圈破坏臭氧机理的正确性.

  8. Application of Box-Behnken design in the optimization of catalytic behavior of a new mixed chelate of copper (II) complex in chemiluminescence reaction of luminol

    International Nuclear Information System (INIS)

    In this work, we observed an enhancement of chemiluminescence (CL) emission of luminol when a new mixed chelate of copper complex (N-(2-(2-aminoethylamino)ethyl)-1H-pyrrole-2-carboxamide-Cu(II)) was mixed with a solution containing luminol in methanol/water. The Box-Behnken design matrix and response surface methodology (RSM) have been applied to design the experiments to evaluate the interactive effects of the three most important operating variables-luminol (10-4-10-2 M), fluorescein (10-5-10-3 M) and hydrogen peroxide (1-3 M) concentrations on the CL emission of luminol. The total 15 experiments were conducted in the present study towards the construction of a quadratic model. Independent variables luminol and hydrogen peroxide have significant value PF less than 0.0500 indicate that model terms are significant for the CL emission of luminol. The regression equation coefficients were calculated and the data fitted to a second-order polynomial equation for CL emission of luminol. The new introduced inorganic catalyst of luminol CL reaction can be effect more than that of the common ones such as potassium hexacyanoferrate (III) and copper (II) acetate. - Research highlights: → In this study we introduce a new mixed chelate of copper complex as a catalyst of luminol chemiluminescence (CL) reaction. → The copper complex (N-(2-(2-aminoethylamino)ethyl)-1H-pyrrole-2-carboxamide-Cu(II)) catalyst luminol reaction more than that of copper acetate and potassium hexacyanoferrate (III). → The Box-Behnken design matrix and response surface methodology are used for prediction of CL intensity of luminol. → There are good correlation between experimental and expected CL intensity that predicted by the theoretical model. → Fluorescein used as a fluorescer in the luminol CL reaction in presence of the new catalyst.

  9. Application of Box-Behnken design in the optimization of catalytic behavior of a new mixed chelate of copper (II) complex in chemiluminescence reaction of luminol

    Energy Technology Data Exchange (ETDEWEB)

    Khajvand, Tahereh [Department of Chemistry, University of Mazandaran, P.O. Box 47416-95447, Babolsar (Iran, Islamic Republic of); Chaichi, Mohammad Javad, E-mail: jchaichi@yahoo.co [Department of Chemistry, University of Mazandaran, P.O. Box 47416-95447, Babolsar (Iran, Islamic Republic of); Nazari, OmLeila; Golchoubian, Hamid [Department of Chemistry, University of Mazandaran, P.O. Box 47416-95447, Babolsar (Iran, Islamic Republic of)

    2011-05-15

    In this work, we observed an enhancement of chemiluminescence (CL) emission of luminol when a new mixed chelate of copper complex (N-(2-(2-aminoethylamino)ethyl)-1H-pyrrole-2-carboxamide-Cu(II)) was mixed with a solution containing luminol in methanol/water. The Box-Behnken design matrix and response surface methodology (RSM) have been applied to design the experiments to evaluate the interactive effects of the three most important operating variables-luminol (10{sup -4}-10{sup -2} M), fluorescein (10{sup -5}-10{sup -3} M) and hydrogen peroxide (1-3 M) concentrations on the CL emission of luminol. The total 15 experiments were conducted in the present study towards the construction of a quadratic model. Independent variables luminol and hydrogen peroxide have significant value P<0.0001, which indicates the importance of these variables in the CL emission of luminol. Values of Prob >F less than 0.0500 indicate that model terms are significant for the CL emission of luminol. The regression equation coefficients were calculated and the data fitted to a second-order polynomial equation for CL emission of luminol. The new introduced inorganic catalyst of luminol CL reaction can be effect more than that of the common ones such as potassium hexacyanoferrate (III) and copper (II) acetate. - Research highlights: In this study we introduce a new mixed chelate of copper complex as a catalyst of luminol chemiluminescence (CL) reaction. The copper complex (N-(2-(2-aminoethylamino)ethyl)-1H-pyrrole-2-carboxamide-Cu(II)) catalyst luminol reaction more than that of copper acetate and potassium hexacyanoferrate (III). The Box-Behnken design matrix and response surface methodology are used for prediction of CL intensity of luminol. There are good correlation between experimental and expected CL intensity that predicted by the theoretical model. Fluorescein used as a fluorescer in the luminol CL reaction in presence of the new catalyst.

  10. Effects of Long-Time Reading Experience on Reaction Time and the Recognition Potential

    OpenAIRE

    Rudell, Alan P.; Hu, Bin

    2010-01-01

    The proposition that long-time experience in reading a language gradually builds up rapidly acting neural processes that facilitate the processing of words in that language and speed them into conscious awareness was examined. Behavioral reaction time (RT) and electrophysiological responsiveness to visually displayed words and non-language images were measured in persons who differed in how much experience they had in reading English. The electrophysiological response was the recognition pote...

  11. Agreement and Null Subjects in German L2 Development: New Evidence from Reaction-Time Experiments.

    Science.gov (United States)

    Clahsen, Harald; Hong, Upyong

    1995-01-01

    Reports on reaction time experiments investigating subject-verb agreement and null subjects in 33 Korean learners of German and a control group of 20 German native speakers. Results found that the two phenomena do not covary in the Korean learners, indicating that properties of agreement and null subjects are acquired separately from one another.…

  12. A Student Laboratory Experiment Based on the Vitamin C Clock Reaction

    Science.gov (United States)

    Vitz, Ed

    2007-01-01

    The Vitamin C Clock Reaction has now been adapted to serve as a student laboratory experiment in the education process of high-school and college-level general chemistry. Despite of imparting valuable knowledge, it also may be hazardous, as the tincture of iodine contains inflammable substances that may cause burning on prolonged exposure.

  13. A Laboratory Experiment, Based on the Maillard Reaction, Conducted as a Project in Introductory Statistics

    Science.gov (United States)

    Kravchuk, Olena; Elliott, Antony; Bhandari, Bhesh

    2005-01-01

    A simple laboratory experiment, based on the Maillard reaction, served as a project in Introductory Statistics for undergraduates in Food Science and Technology. By using the principles of randomization and replication and reflecting on the sources of variation in the experimental data, students reinforced the statistical concepts and techniques…

  14. Impact of transamination reactions and protein turnover on labeling dynamics in C-13-labeling experiments

    DEFF Research Database (Denmark)

    Grotkjær, Thomas; Åkesson, M.; Christensen, Bjarke;

    2004-01-01

    A dynamic model describing carbon atom transitions in the central metabolism of Saccharomyces cerevisiae is used to investigate the influence of transamination reactions and protein turnover on the transient behavior of C-13-labeling chemostat experiments. The simulations performed suggest that c...

  15. Affective Game Design: Creating Better Game Experiences based on Players Affective Reaction Model

    OpenAIRE

    Rúben Pinto Aguiar

    2014-01-01

    In this thesis, we demonstrate a generalizable approach for building predictive models of players’ affective reactions across games and genres. Our aim is two-fold: 1) That game developers can use these models to more easily and accurately tune game parameters, allowing improved gaming experiences, and 2) That these models can be used as the basis for parameterisable and adaptive affective gaming.

  16. Do victimization experiences accentuate reactions to ostracism? An experiment using cyberball

    OpenAIRE

    Ruggieri, Sabrina; Bendixen, Mons; Gabriel, Ute; Alsaker, Françoise

    2013-01-01

    Based on the notion that the history of victimization has an impact on the sensitivity to current victimization situations this study investigated whether victims of bullying show more pronounced responses to single episodes of social exclusion. We examined whether victimization experiences in school are associated with responses to ostracism in a virtual ball tossing game (Cyberball). We compared two groups of students: 26 victims of bullying and 32 students not involved in bully/victim prob...

  17. Experiments on high temperature graphite and steam reactions under loss of coolant accident conditions

    International Nuclear Information System (INIS)

    To obtain fundamental data for safety analyses of fusion reactors with regard to loss of coolant inside the vacuum vessel, the rate of corrosion reaction between high temperature graphite and steam was measured experimentally between 1000 and 1600 C. A preliminary experiment gave an activation energy for reaction between oxygen and isotropic graphite as 45kJmol-1. The reaction rate with steam depended on temperature, with an inflection point near 1300 C. The activation energy was about 270kJmol-1 at temperatures below 1300 C, and 104kJmol-1 at higher temperatures. The energy was not strongly dependent on the graphite properties, but the reaction rate varied with them. The reactivity of the isotropic graphite was more than twice as high as that of C/C composite. The molar ratio of the product gases [H2]/[CO] increased slightly with increasing temperature. Although the [CO]/[CO2] ratio also increased with temperature to 1300 C, it decreased above this temperature. This behavior reflects a change in reaction mechanism near this temperature; the composition of the product gas could be estimated numerically using elementary reaction rates. (orig.)

  18. Novel Catalytic Membrane Reactors

    Energy Technology Data Exchange (ETDEWEB)

    Stuart Nemser, PhD

    2010-10-01

    There are many industrial catalytic organic reversible reactions with amines or alcohols that have water as one of the products. Many of these reactions are homogeneously catalyzed. In all cases removal of water facilitates the reaction and produces more of the desired chemical product. By shifting the reaction to right we produce more chemical product with little or no additional capital investment. Many of these reactions can also relate to bioprocesses. Given the large number of water-organic compound separations achievable and the ability of the Compact Membrane Systems, Inc. (CMS) perfluoro membranes to withstand these harsh operating conditions, this is an ideal demonstration system for the water-of-reaction removal using a membrane reactor. Enhanced reaction synthesis is consistent with the DOE objective to lower the energy intensity of U.S. industry 25% by 2017 in accord with the Energy Policy Act of 2005 and to improve the United States manufacturing competitiveness. The objective of this program is to develop the platform technology for enhancing homogeneous catalytic chemical syntheses.

  19. Molecular Simulation of Naphthenic Acid Removal on Acidic Catalyst Ⅱ. Experimental results of catalytic decarboxylation over acidic catalysts

    Institute of Scientific and Technical Information of China (English)

    Fu Xiaoqin; Tian Songbai; Hou Shuandi; Longjun; Wang Xieqing

    2008-01-01

    The energy barriers of thermal decarboxylation reactions of petroleum acids and catalytic decarboxylation reactions of Br(o)nsted acid and Lewis acid were analyzed using molecular simulation technology.Compared with thermal decarboxylation reactions of petroleum acids, the decarboxylation reactions by acid catalysts were easier to occur. The decarboxylaton effect by Lewis acid was better than Br(o)nsted acid. The mechanisms of catalytic decarboxylation over acid catalyst were also verified by experiments on a fixed bed and a fluidized bed, the experimental results showed that the rate of acid removal could reach up to 97% over the acidic catalyst at a temperature above 400℃.

  20. Using a dual plasma process to produce cobalt--polypyrrole catalysts for the oxygen reduction reaction in fuel cells -- part I: characterisation of the catalytic activity and surface structure

    CERN Document Server

    Walter, Christian; Vyalikh, Denis; Brüser, Volker; Quade, Antje; Weltmann, Klaus-Dieter; 10.1149/2.078208jes

    2012-01-01

    A new dual plasma coating process to produce platinum-free catalysts for the oxygen reduction reaction in a fuel cell is introduced. The catalysts thus produced were analysed with various methods. Electrochemical characterisation was carried out by cyclic voltammetry, rotating ring- and rotating ring-disk electrode. The surface porosity of the different catalysts thus obtained was characterised with the nitrogen gas adsorption technique and scanning electron microscopy was used to determine the growth mechanisms of the films. It is shown that catalytically active compounds can be produced with this dual plasma process. Furthermore, the catalytic activity can be varied significantly by changing the plasma process parameters. The amount of H$_2$O$_2$ produced was calculated and shows that a 2 electron mechanism is predominant. The plasma coating mechanism does not significantly change the surface BET area and pore size distribution of the carbon support used. Furthermore, scanning electron microscopy pictures o...

  1. LaMn1-xFe xO3 and LaMn0.1-xFe0.90Mo x O3 perovskites: synthesis, characterization and catalytic activity in H2O2 reactions

    Directory of Open Access Journals (Sweden)

    Fabiano Magalhães

    2008-09-01

    Full Text Available In this work two perovskites were prepared: LaMn1-xFe xO3, and LaMn0.1-x Fe0.90Mo xO3. XRD and Mössbauer spectroscopy suggest the formation of pure phase perovskite with the incorporation of Fe and Mo in the structure. The catalytic activity of these materials was studied in two reactions with H2O2: the decomposition to O2, and the oxidation of the model organic contaminant methylene blue. The perovskite composition strongly affects the catalytic activity, while Fe decreases the H2O2 decomposition Mo strongly improves dye oxidation.

  2. Validation of a lattice Boltzmann model for gas–solid reactions with experiments

    International Nuclear Information System (INIS)

    A lattice Boltzmann method is used to model gas–solid reactions where the composition of both the gas and solid phase changes with time, while the boundary between phases remains fixed. The flow of the bulk gas phase is treated using a multiple relaxation time MRT D3Q19 model; the dilute reactant is treated as a passive scalar using a single relaxation time BGK D3Q7 model with distinct inter- and intraparticle diffusivities. A first-order reaction is incorporated by modifying the method of Sullivan et al. to include the conversion of a solid reactant. The detailed computational model is able to capture the multiscale physics encountered in reactor systems. Specifically, the model reproduced steady state analytical solutions for the reaction of a porous catalyst sphere (pore scale) and empirical solutions for mass transfer to the surface of a sphere at Re = 10 (particle scale). Excellent quantitative agreement between the model and experiments for the transient reduction of a single, porous sphere of Fe2O3 to Fe3O4 in CO at 1023 K and 105 Pa is demonstrated. Model solutions for the reduction of a packed bed of Fe2O3 (reactor scale) at identical conditions approached those of experiments after 25 s, but required prohibitively long processor times. The presented lattice Boltzmann model resolved successfully mass transport at the pore, particle and reactor scales and highlights the relevance of LB methods for modelling convection, diffusion and reaction physics.

  3. QRTEngine: An easy solution for running online reaction time experiments using Qualtrics.

    Science.gov (United States)

    Barnhoorn, Jonathan S; Haasnoot, Erwin; Bocanegra, Bruno R; van Steenbergen, Henk

    2015-12-01

    Performing online behavioral research is gaining increased popularity among researchers in psychological and cognitive science. However, the currently available methods for conducting online reaction time experiments are often complicated and typically require advanced technical skills. In this article, we introduce the Qualtrics Reaction Time Engine (QRTEngine), an open-source JavaScript engine that can be embedded in the online survey development environment Qualtrics. The QRTEngine can be used to easily develop browser-based online reaction time experiments with accurate timing within current browser capabilities, and it requires only minimal programming skills. After introducing the QRTEngine, we briefly discuss how to create and distribute a Stroop task. Next, we describe a study in which we investigated the timing accuracy of the engine under different processor loads using external chronometry. Finally, we show that the QRTEngine can be used to reproduce classic behavioral effects in three reaction time paradigms: a Stroop task, an attentional blink task, and a masked-priming task. These findings demonstrate that QRTEngine can be used as a tool for conducting online behavioral research even when this requires accurate stimulus presentation times. PMID:25407763

  4. Benchmark experiments for validation of reaction rates determination in reactor dosimetry

    International Nuclear Information System (INIS)

    The precision of Monte Carlo calculations of quantities of neutron dosimetry strongly depends on precision of reaction rates prediction. Research reactor represents a very useful tool for validation of the ability of a code to calculate such quantities as it can provide environments with various types of neutron energy spectra. Especially, a zero power research reactor with well-defined core geometry and neutronic properties enables precise comparison between experimental and calculated data. Thus, at the VR-1 zero power research reactor, a set of benchmark experiments were proposed and carried out to verify the MCNP Monte Carlo code ability to predict correctly the reaction rates. For that purpose two frequently used reactions were chosen: He-3(n,p)H-3 and Au-197(n,γ)Au-198. The benchmark consists of response measurement of small He-3 gas filled detector in various positions of reactor core and of activated gold wires placed inside the core or to its vicinity. The reaction rates were calculated in MCNP5 code utilizing a detailed model of VR-1 reactor which was validated for neutronic calculations at the reactor. The paper describes in detail the experimental set-up of the benchmark, the MCNP model of the VR-1 reactor and provides a comparison between experimental and calculated data. - Highlights: • Use of zero power reactor for validation of reaction rates calculations. • Reaction rates measurement in reactor core by He-3 detector and Au wires. • Validation of reaction rates calculation by MCNP5. • Comparison of measured and calculated RR for different positions in core

  5. Preparation of Rh-TPPTS complex intercalated layered double hydroxide and influences of host and guest compositions on its catalytic performances in hydroformylation reaction

    Institute of Scientific and Technical Information of China (English)

    ZHANG Xian; LU Jun; JIN Lan; WEI Min

    2008-01-01

    Based on the concept of intercalation chemistry of layered double hydroxides (LDHs), RhCI(GO)-(TPPTS)2 (TPPTS: P(m-C6H4SO3Na)3) and TPPTS co-intercalated LDHs were successfully synthesized by in situ complexation method. Characterizations of structure and composition of composite materials by powder XRD, FT-IR, and ICP-AES techniques confirmed the supramolecular structures of the catalytic species intercalated LDHs. The correlation between catalytic performance of intercalated catalyst and the composition of both host layers and interlayer guest species was also investigated.

  6. Medical Students’ Experience of and Reaction to Stress: The Role of Depression and Anxiety

    OpenAIRE

    2014-01-01

    Background. Medical school is recognized as a stressful environment that often has a negative effect on students' academic performance, physical health, and psychosocial well-being. Previous studies have not identified differences between depressed and nondepressed and anxious and nonanxious medical students' experiences of stress or their reactions to stressors. The present study aimed to identify the prevalence of depression and anxiety among a sample of 358 medical students attending a pri...

  7. Medical Students' Experience of and Reaction to Stress: The Role of Depression and Anxiety

    OpenAIRE

    Coumaravelou Saravanan; Ray Wilks

    2014-01-01

    Background. Medical school is recognized as a stressful environment that often has a negative effect on students' academic performance, physical health, and psychosocial well-being. Previous studies have not identified differences between depressed and nondepressed and anxious and nonanxious medical students' experiences of stress or their reactions to stressors. The present study aimed to identify the prevalence of depression and anxiety among a sample of 358 medical students attending a pri...

  8. Design, construction and implementation of a packed reactor system to study the production of hydrogen by the catalytic reaction of reforming of oxygenated hydrocarbons

    International Nuclear Information System (INIS)

    The Laboratorio de Quimica Inorganica of the Universidad de Costa Rica has evaluated the performance of several types of catalysts and supports in steam reforming reactions, using different conditions for synthesis of the same. The construction of a reaction system at laboratory scale is described to improve the conditions of the reforming process compared to previous projects. Catalysts synthesized and characterized are used but providing better disposal through a packed bed reactor. The system has had the necessary instrumentation for proper measurement of the temperature at the entrance and inside the reactor, proper feeding of reactants, flow measurement and sampling and measurement system. The conceptual design of the reactions system presented has taken into account the income of reactants through a peristaltic pump, preheating or vaporization of reagents, income and measurement of carrier gas sampling, take of sampling, flow measurement product, reactor packed and cooler product. The order of each stage is defined and positioning in the entire system. The design of a preheater and a tubular reactor is detailed, taking into account the dimensions and construction materials of each of the pieces. The design is presented in a series of diagrams and then the result of the construction is illustrated by photographs, all work done also has been described. The implementation of the system has described by the coupling of all parties and the respective tests. A basic experimental plan is presented to evaluate the performance of the reaction system, using glycerin as a reactant, demonstrating ability to react and take effective data. Four experiments are performed: vacuum reactor, packed reactor with two types of filling and reactor with an exposed surface cobalt oxide (II) reduced, the gases produced in the reaction are analyzed by gas chromatography. The results are discussed and analyzed, focusing on the overall selectivity of hydrogen relative to methane, and the

  9. Adverse allergic reactions to linear ionic gadolinium-based contrast agents: experience with 194, 400 injections

    International Nuclear Information System (INIS)

    Aim: To report the authors' experience with the administration of four gadolinium-based contrast agents (GBCA; gadopentetate dimeglumine, gadofosveset trisodium, gadoxetate disodium and gadobenate dimeglumine) in a large study population at a single, large academic medical centre. Materials and methods: The institutional review board approved this retrospective study in which data in the electronic incident reporting system were searched. A total of 194, 400 intravenous administrations of linear ionic GBCAs were assessed for the incidence of adverse reactions and risk factors from 1 January 2007 to 14 January 2014. The severity of reactions (mild, moderate, and severe), patient type (outpatients, inpatients, and emergency), examination type, and treatment options were also investigated. Results: In total, 204/194400 (0.1%) patients (mean age 45.7 ± 14.9) showed adverse reactions, consisting of 6/746 (0.80%), 10/3200 (0.31%), 14/6236 (0.22%) and 174/184218 (0.09%), for gadofosveset trisodium, gadoxetate disodium, gadobenate dimeglumine, and gadopentetate dimeglumine, respectively. An overall significant difference was found between different GBCAs regarding the total number of reactions (p < 0.0001). When comparing the GBCAs together, significant differences were found between gadofosveset trisodium versus gadopentetate dimeglumine (p < 0.0001), gadofosveset trisodium versus gadobenate dimeglumine (p = 0.0051), gadoxetate disodium versus gadopentetate dimeglumine (p < 0.0001) and gadopentetate dimeglumine versus gadobenate dimeglumine (p = 0.0013). Rate of reaction was higher in females (F: 146/113187, 0.13%/M: 58/81213, 0.07%; p < 0.0001). Rate of reactions was higher in outpatient (180/158885, 0.11%), emergency (10/10413, 0.10%), and inpatients (14/25102, 0.05%), respectively (p < 0.0001). Most of the patients had mild symptoms 171/204 (83.8%). Abdomen–pelvis, liver, and thoracic examinations had highest rates of reactions (0.17 versus 0

  10. Comparison of the catalytic activity for the Suzuki–Miyaura reaction of (η5-Cp)Pd(IPr)Cl with (η3-cinnamyl)Pd(IPr)(Cl) and (η3-1-t-Bu-indenyl)Pd(IPr)(Cl)

    Science.gov (United States)

    Melvin, Patrick R; Lant, Hannah M C; Peczak, Ian L; Shah, Hemali P

    2015-01-01

    Summary Complexes of the type (η3-allyl)Pd(L)(Cl) and (η3-indenyl)Pd(L)(Cl) are highly active precatalysts for the Suzuki–Miyaura reaction. Even though allyl and indenyl ligands are similar to cyclopentadienyl (Cp) ligands, there have been no detailed comparative studies exploring the activity of precatalysts of the type (η5-Cp)Pd(L)(Cl) for Suzuki–Miyaura reactions. Here, we compare the catalytic activity of (η5-Cp)Pd(IPr)(Cl) (IPr = 1,3-bis(2,6-diisopropylphenyl)-1,3-dihydro-2H-imidazol-2-ylidene, Cp) with two commercially available catalysts (η3-cinnamyl)Pd(IPr)(Cl) (Cin) and (η3-1-t-Bu-indenyl)Pd(IPr)(Cl) (tBu Ind). We show that Cp gives slightly better catalytic activity than Cin, but significantly inferior activity than tBu Ind. This order of activity is rationalized by comparing the rates at which the precatalysts are activated to the monoligated Pd(0) active species along with the tendency of the starting precatalysts to comproportionate with monoligated Pd(0) to form inactive Pd(I) dimers. As part of this work the Cp supported Pd(I) dimer (μ-Cp)(μ-Cl)Pd2(IPr)2 (Cp Dim) was synthesized and crystallographically characterized. It does not readily disproportionate to form monoligated Pd(0) and consequently Cp Dim is a poor catalyst for the Suzuki–Miyaura reaction. PMID:26732227

  11. Numerical and experimental investigations on catalytic recombiners

    International Nuclear Information System (INIS)

    Numerous containments of European light water reactors (LWR) are equipped with passive auto-catalytic recombiners (PAR). These devices are designed for the removal of hydrogen generated during a severe accident in order to avoid serious damage caused by a detonation. PARs make use of the fact that hydrogen and oxygen react exothermally on catalytic surfaces generating steam and heat even below conventional ignition concentrations and temperatures. Activities at ISR aim at overcoming existing limitations of today's systems. These are e.g. limited conversion capacity or unintended ignition of the gaseous mixture due to overheating of the catalyst elements caused by strong reaction heat generation. Experiments at the REKO facilities are conducted in order to achieve a profound understanding of the processes inside a recombiner, such as reaction kinetics or heat and mass transfer. Innovative PAR designs which may overcome existing limitations can be developed based on the knowledge obtained from these experiments. For the analysis of the processes inside a PAR the numerical code REKO-DIREKT is being developed. The code calculates the local catalyst temperatures and the concentration regression along the catalyst plates. For the validation of the model numerous experiments have been performed with different types of coating and different plate arrangements. The first calculations fit well with the experimental results indicating a proper understanding of the fundamental processes. The paper describes the experiments as well as the numerical model and presents model calculations in comparison with experimental results. (authors)

  12. "Hydro-metathesis" of olefins: A catalytic reaction using a bifunctional single-site tantalum hydride catalyst supported on fibrous silica (KCC-1) nanospheres

    KAUST Repository

    Polshettiwar, Vivek

    2011-02-18

    Tantalizing hydrocarbons: Tantalum hydride supported on fibrous silica nanospheres (KCC-1) catalyzes, in the presence of hydrogen, the direct conversion of olefins into alkanes that have higher and lower numbers of carbon atoms (see scheme). This catalyst shows remarkable catalytic activity and stability, with excellent potential of regeneration. Copyright © 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  13. Study on the adsorptive catalytic voltammetry of aloe-emodin at a carbon paste electrode

    Institute of Scientific and Technical Information of China (English)

    LI; Ju'nan; GAO; Peng; LI; Xiangling; YAN; Zhihong; MAO; Xu

    2005-01-01

    A new catalytic voltammetric method for the determination of anthraqunone medicines at a carbon paste electrode (CPE) was described for the first time. The mechanism of the catalytic reaction was investigated by using linear sweep voltammetry, cyclic voltammetry, constant potential electrolysis and so on. The experiment results indicate that aloe-emodin was efficiently accumulated at a CPE by adsorption. In the following potential scan, aloe-emodin was reduced to homologous anthrahydroquinone compound, then the compound was immediately oxidized to aloe-emodin by the dissolved oxygen, and the aloe-emodin was again reduced at the CPE. As a result, a cyclic catalytic reaction was established. But a reversible redox reaction of aloe-emodin can only be observed at a mercury electrode, no catalytic reaction occurs there. A sensitive catalytic voltammetric peak of aloe-emodin was obtained at about -0.60 V (vs. SCE) in 0.56 mol/L NH3-NH4Cl buffer (pH 8.9). The proposed method was applied to the determination of aloe-emodin in the Radix Rhei with satisfactory results. The determination results were in good agreement with reference values obtained by the HPLC. The adsorptive catalytic voltammetry for the determination of organic compound at CPE, chemically modified electrode and other solid electrodes could be significant in the studies on pharmacology, pharmacodynamics, toxicity of medicine, clinical medicine and biochemistry.

  14. Review of the sodium fire experiments including sodium-concrete-reactions and summary of the results

    International Nuclear Information System (INIS)

    In the technical and design concept of containment systems of sodium cooled breeder reactors it has to be considered, that leakages in sodium pipes lead to sodium fires. The temperature and pressure rise caused by sodium fires makes it indispensable to analyse these accidents to be able to assess the safety of the whole system. Generally sodium leakages may lead to three different types of fires with different consequences. The main influences are the geometry of the leakage, shape, size, location, and the sodium conditions, such as temperature, flow rate and velocity. It must be also considered the reaction of sodium with surfaces like concrete. The paper gives an overview over all the sodium fire experiments performed in the FAUNA-facility (220 m3) of the Forschungszentrum Karlsruhe in the years 1979 to 1993. The experimental program started with the investigation of pool fires on burning areas between 2 and 12 m2 with up to 500 kg of Sodium. The experiments had been continued with 3 combined fires and 40 experiments on spray fires. 7 experiments on sodium-concrete reactions completed the program. (author)

  15. Reforming of methane in tubes with a catalytic active wall

    International Nuclear Information System (INIS)

    The heterogeneous steam reforming process in tubes with catalytic active inner surface is studied. The purpose of this ivestigation is to find a method of predicting the reaction rate of the catalytic conversion of methane by steam. The dependency of the reaction rate upon the temperature, pressure, gas composition, Reynolds number, geometrical sizes of tubes and catalytic behaviour of the catalytic active inner wall of these tubes has been examined. It was found that the reaction rate mainly depends on the temperature. The reaction rate is limited by the catalytic behaviour and the heat resisting properties of the materials used. (author)

  16. Reações de Etanol com CO/H2 na Presença do Sistema Catalítico Ru(acac3/I- Ethanol, reactions with co/h2 in the presence of the ru(acac3/i- catalytic system

    Directory of Open Access Journals (Sweden)

    Elizeu Trabuco

    1997-06-01

    Full Text Available The hydrocarbonylation reaction of ethanol with a CO/H2 mixture assisted by Ru(acac3/iodide was investigated. Bronsted and Lewis acids and iodides salt were used as homogeneous promoters. The etherification reaction was the main reaction under typical acidic conditions of the catalytic system. When a hydrocarbon solvent (toluene was added to the initial reaction, the alcohol conversion and the carbonylation products were increased. The catalytic activity of the Bronsted acids (conv. EtOH = 71-92% was higher than that of the Lewis acids promoters (conv. EtOH = 65-85%. The salt present the lower catalytic activity among the promoters used. The long time reaction carried out with ethanol showed an increase of the product selectivity of the homologation and carbonylation reactions while the etherification reaction selectivity decreased. The recycled ether led to 60-65% ethanol conversion to C5 and C6 products. The main catalytic species are H+[Ru(CO3I3]-, [HRu3(CO11]- and [HRu(CO4]-. The first one is active in the carbonylation and homologation reactions of alcohols while the two others take part only in the homologation reaction.

  17. Numerical experiments with the Lamellae Upscaling Concept with Approximate Handling of Coalescence of the Reaction Front

    Science.gov (United States)

    Nassar, M.; Ginn, T. R.; Le Borgne, T.; Schreyer, L. G.; Dentz, M.

    2015-12-01

    The challenge in characterizing mixing-limited reaction rates between displacing and displaced groundwater solutions (Figure 1, left panel) is the in quantifying mixing extent that is controlled by small scale heterogeneity. We describe limited numerical 2D testing of the lamella approach that focuses on the deformation of the moving front, treated as a set of linearized patches termed lamellae. We simulate flow and reactive transport in a recently characterized sample of Massillon sandstone to provide Eulerian test data for comparison with the new Lagrangian lamella-based solution. In our numerical experiments particle tracking is used to approximate the lamellar positions and deformations at any given time, and reactions are calculated on each lamella in proportion to the local scalar dissipation rate. The simulated data show the effect of small scale heterogeneity including strong shearing and local collapse or coalescence (Figure 1, right panel) of the reaction front on the global reaction rate. We propose a simple approximation to handle coalescence in the lamella-based upscaling and we test it against the simulated data.

  18. Reactions

    DEFF Research Database (Denmark)

    Søndergaard, Morten

    2011-01-01

    ) museum. Augmentation, in this expanding digital field, is part of a production of new public spaces, as well as a new reality that affects and traverses art and institutions immanently and througout. The expanding digital field is transforming art and the art museum in a number of fundamental ways, a few......; It is in this negotiation, I would claim, that the foundation of a possible critique of the role of the (art) museum in the age of post-bourgeois public space and experience-based culture should be located....

  19. Water formation reaction on Pt(111): Near edge x-ray absorption fine structure experiments and kinetic Monte Carlo simulations

    International Nuclear Information System (INIS)

    The catalytic water formation reaction was investigated by the energy dispersive near-edge x-ray absorption fine structure (dispersive NEXAFS) spectroscopy. An oxygen covered Pt(111) surface with the (2x2) structure was exposed to gaseous hydrogen (5.0x10-9 Torr) at constant surface temperatures (120-140 K). O K-edge NEXAFS spectra were measured during the reaction with a time interval of 35 s. Quantitative analyses of the spectra provided the coverage changes of the adsorbed species (O, OH, and H2O). The reaction is composed of three steps, which are characterized by an induction period (I), fast increase in coverage of OH and H2O with consuming O (II), and slow conversion of OH to H2O after the complete consumption of O (III). It was also found that the maximum OH coverage becomes smaller at a higher temperature. The kinetic Monte Carlo simulation has reproduced the three characteristic reaction steps; in the first step OH domains are created through two-dimensional aggregation of H2O (I), after the nucleation process the second step sets in where the OH domains propagate by the autocatalytic cycle until they contact with each other (II), and finally the merged OH domains convert to H2O (III). The reaction diffusion method was also applied to this system. It explained the reaction behavior in a wide surface area

  20. Role of Associated Defects in Oxygen Ion Conduction and Surface Exchange Reaction for Epitaxial Samaria-Doped Ceria Thin Films as Catalytic Coatings.

    Science.gov (United States)

    Yang, Nan; Shi, Yanuo; Schweiger, Sebastian; Strelcov, Evgheni; Belianinov, Alex; Foglietti, Vittorio; Orgiani, Pasquale; Balestrino, Giuseppe; Kalinin, Sergei V; Rupp, Jennifer L M; Aruta, Carmela

    2016-06-15

    Samaria-doped ceria (SDC) thin films are particularly important for energy and electronic applications such as microsolid oxide fuel cells, electrolyzers, sensors, and memristors. In this paper, we report a comparative study investigating ionic conductivity and surface reactions for well-grown epitaxial SDC films varying the samaria doping concentration. With increasing doping above 20 mol % of samaria, an enhancement in the defect association is observed by Raman spectroscopy. The role of such associated defects on the films̀ oxygen ion transport and exchange is investigated by electrochemical impedance spectroscopy and electrochemical strain microscopy (ESM). The measurements reveal that the ionic transport has a sharp maximum in ionic conductivity and drops in its activation energy down to 0.6 eV for 20 mol % doping. Increasing the doping concentration further up to 40 mol %, it raises the activation energy substantially by a factor of 2. We ascribe the sluggish transport kinetics to the "bulk" ionic-near ordering in case of the heavily doped epitaxial films. Analysis of the ESM first-order reversal curve measurements indicates that these associated defects may have a beneficial role by lowering the activation of the oxygen exchange "surface" reaction for heavily doped 40 mol % of samaria. In a model experiment, through a solid solution series of samaria doped ceria epitaxial films, we reveal that the occurrence of associated defects in the bulk affects the surface charging state of the SDC films to increase the exchange rates. The implication of these findings is the design of coatings with tuned oxygen surface exchange by controlling the bulk associated clusters for future electrocatalytic applications. PMID:27192540

  1. Oscillatory reactions on single crystal surfaces

    Science.gov (United States)

    Imbihl, R.

    1993-12-01

    Heterogeneous catalytic reactions exhibit under certain conditions kinetic oscillations which have been investigated both with polycrystalline materials and with single crystal surfaces as catalysts. The present paper reviews single-crystal experiments conducted under isothermal, low pressure conditions ( p Turing structures and the appearance of deterministic chaos, and chemical turbulence. The mechanistic steps leading to the observed phenomena have been investigated and appropriate mathematical models have been formulated and analyzed using bifurcation theory. The driving force for the rate oscillations has been shown to result from structural changes of the substrate in the case of catalytic CO oxidation on Pt surfaces, subsurface oxygen formation in the case of catalytic CO oxidation on Pd surfaces, and in the chemical reaction network described by a vacancy model in the case of the NO reduction reactions.

  2. Computer model for the transport and chemical reaction of debris in direct containment heating experiments

    International Nuclear Information System (INIS)

    The transport and chemical reaction of debris is a problem of current interest in the study of certain nuclear reactor accident scenarios. In some situations, debris from the core of a reactor could be expelled into the atmosphere inside a reactor containment building. The debris would then heat the gas, resulting in an increase in the pressure in the containment. Furthermore, the exothermic reaction of the debris with the oxygen in the air would cause additional heating of the atmosphere. The present work is part of a study being carried out to determine whether this heating will be sufficient to place the integrity of the containment building at risk due to overpressurization. The authors have developed methods for computer simulation of some of the physical processes involved in such direct containment heating (DCH) configurations. In this paper, these numerical algorithms are used to model experiments pertinent to the reactor debris dispersal problem. The resulting computer code, referred to as Kiva-DCH, has been applied to the simulation of experiments performed in the Surtsey facility at Sandia National Laboratories in Albuquerque, New Mexico. It is found that the computational results agree well with those obtained from an experiment conducted at modest debris mass

  3. On the Structural Context and Identification of Enzyme Catalytic Residues

    OpenAIRE

    Yu-Tung Chien; Shao-Wei Huang

    2013-01-01

    Enzymes play important roles in most of the biological processes. Although only a small fraction of residues are directly involved in catalytic reactions, these catalytic residues are the most crucial parts in enzymes. The study of the fundamental and unique features of catalytic residues benefits the understanding of enzyme functions and catalytic mechanisms. In this work, we analyze the structural context of catalytic residues based on theoretical and experimental structure flexibility. The...

  4. Fundamental studies of the mechanism of catalytic reactions with catalysts effective in the gasification of carbon solids and the oxidative coupling of methane. Quarterly report, July 1--September 30, 1992

    Energy Technology Data Exchange (ETDEWEB)

    Heinemann, H.; Somorjai, G.A.; Perry, D.L.

    1992-09-01

    Work will continue on the oxidative coupling reaction of methane over ternary oxide catalysts to produce C{sub 2}, C{sub 3} and C{sub 4} hydrocarbons and Particularly Olefins with high selectivity. The work which has shown that close to 100% selectivity can be obtained has received wide attention and has resulted in collaborative efforts with industry (CRADA) towards the development of a commercial process. An immediate purpose of additional work is to increase the conversion without diminishing the extremely high selectivity of the reaction and also to permit operation at higher space velocity to reduce equipment size. The mechanism of this reaction is not understood and much additional work is needed to explain the role of carbon formation and of water as intermediates in the reaction and to investigate whether carbon oxides are intermediates. It has been found that oxides other than calcium-nickel-potassium oxides can be useful catalysts for this reaction in the presence of steam and at relatively low temperatures and long contact times. Better definition of the class of binary metal oxides is required and better catalyst characterization is needed to ensure reproducibility Of catalyst preparation and operational results. Pretreatment of the catalyst should be shortened and higher space velocities must be obtained. Close collaboration with Orion ACT is required to advance the project toward the pilot plant stage. In the area of coal and char catalytic steam gasification, the large volume of data obtained at atmospheric pressure will be extended to operations at higher pressures.

  5. Analysis of heterogeneous oxygen exchange and fuel oxidation on the catalytic surface of perovskite membranes

    KAUST Repository

    Hong, Jongsup

    2013-10-01

    The catalytic kinetics of oxygen surface exchange and fuel oxidation for a perovskite membrane is investigated in terms of the thermodynamic state in the immediate vicinity of or on the membrane surface. Perovskite membranes have been shown to exhibit both oxygen perm-selectivity and catalytic activity for hydrocarbon conversion. A fundamental description of their catalytic surface reactions is needed. In this study, we infer the kinetic parameters for heterogeneous oxygen surface exchange and catalytic fuel conversion reactions, based on permeation rate measurements and a spatially resolved physical model that incorporates detailed chemical kinetics and transport in the gas-phase. The conservation equations for surface and bulk species are coupled with those of the gas-phase species through the species production rates from surface reactions. It is shown that oxygen surface exchange is limited by dissociative/associative adsorption/desorption of oxygen molecules onto/from the membrane surface. On the sweep side, while the catalytic conversion of methane to methyl radical governs the overall surface reactions at high temperature, carbon monoxide oxidation on the membrane surface is dominant at low temperature. Given the sweep side conditions considered in ITM reactor experiments, gas-phase reactions also play an important role, indicating the significance of investigating both homogeneous and heterogeneous chemistry and their coupling when examining the results. We show that the local thermodynamic state at the membrane surface should be considered when constructing and examining models of oxygen permeation and heterogeneous chemistry. © 2013 Elsevier B.V.

  6. Research on degradation product and reaction kinetics of membrane electro-bioreactor (MEBR) with catalytic electrodes for high concentration phenol wastewater treatment.

    Science.gov (United States)

    Wang, Tao; Zhao, Huanping; Wang, Hui; Liu, Botan; Li, Chunqing

    2016-07-01

    The membrane electro-bioreactor (MEBR) is a novel technology, it treats wastewater by combining membrane filtration, electrokinetic phenomena, and biological processes in one reactor. This paper aims to deal with hard biodegradation and high concentration phenol wastewater. Investigating the influence factors such as initial concentration, voltage, pH value, temperature and mixed liquor suspended solids (MLSS) toward phenol degradation process in electrocatalytic process and membrane bioreactor (MBR), and then apply the optimum conditions in the MEBR system. Results of continuous flow experiments demonstrated that MEBR increased the quality of the treated wastewater than conventional MBR. The above technics followed the zero-order reaction kinetics. The removal efficiency of MEBR was about 11.1% higher for phenol than the sum of the two individual processes. With the help of gas chromatography/mass spectrometry (GC-MS), this qualitative analysis looks at the degradation products of phenol generated in MEBR, through which 2,6-di-tert-butyl-p-benzoquinone was confirmed as the main degradation product. PMID:27108366

  7. Revisited reaction-diffusion model of thermal desorption spectroscopy experiments on hydrogen retention in material

    International Nuclear Information System (INIS)

    Desorption phase of thermal desorption spectroscopy (TDS) experiments performed on tungsten samples exposed to flux of hydrogen isotopes in fusion relevant conditions is analyzed using a reaction-diffusion model describing hydrogen retention in material bulk. Two regimes of hydrogen desorption are identified depending on whether hydrogen trapping rate is faster than hydrogen diffusion rate in material during TDS experiments. In both regimes, a majority of hydrogen released from material defects is immediately outgassed instead of diffusing deeply in material bulk when the evolution of hydrogen concentration in material is quasi-static, which is the case during TDS experiments performed with tungsten samples exposed to flux of hydrogen isotopes in fusion related conditions. In this context, analytical expressions of the hydrogen outgassing flux as a function of the material temperature are obtained with sufficient accuracy to describe main features of thermal desorption spectra (TDSP). These expressions are then used to highlight how characteristic temperatures of TDSP depend on hydrogen retention parameters, such as trap concentration or activation energy of detrapping processes. The use of Arrhenius plots to characterize retention processes is then revisited when hydrogen trapping takes place during TDS experiments. Retention processes are also characterized using the shape of desorption peaks in TDSP, and it is shown that diffusion of hydrogen in material during TDS experiment can induce long desorption tails visible aside desorption peaks at high temperature in TDSP. These desorption tails can be used to estimate activation energy of diffusion of hydrogen in material

  8. Formic Acid Decomposition on Au catalysts: DFT, Microkinetic Modeling, and Reaction Kinetics Experiments

    Energy Technology Data Exchange (ETDEWEB)

    Singh, Suyash; Li, Sha; Carrasquillo-Flores, Ronald; Alba-Rubio, Ana C.; Dumesic, James A.; Mavrikakis, Manos

    2014-04-01

    A combined theoretical and experimental approach is presented that uses a comprehensive mean-field microkinetic model, reaction kinetics experiments, and scanning transmission electron microscopy imaging to unravel the reaction mechanism and provide insights into the nature of active sites for formic acid (HCOOH) decomposition on Au/SiC catalysts. All input parameters for the microkinetic model are derived from periodic, self-consistent, generalized gradient approximation (GGA-PW91) density functional theory calculations on the Au(111), Au(100), and Au(211) surfaces and are subsequently adjusted to describe the experimental HCOOH decomposition rate and selectivity data. It is shown that the HCOOH decomposition follows the formate (HCOO) mediated path, with 100% selectivity toward the dehydrogenation products (CO21H2) under all reaction conditions. An analysis of the kinetic parameters suggests that an Au surface in which the coordination number of surface Au atoms is 4 may provide a better model for the active site of HCOOH decomposition on these specific supported Au catalysts.

  9. Monopropellant engine investigation for space shuttle reaction control. Volume 2: Design, fabrication, and demonstration test of a catalytic gas generator for the space shuttle APU

    Science.gov (United States)

    1975-01-01

    The capability of a catalytic gas generator to meet the requirement specified for the space shuttle APU is established. A full-scale gas generator, designed to operate at a chamber pressure of 750 psia and a flow rate of 0.36 lbm/sec, was fabricated and subjected to three separate life test series. The nickel foam metal used for catalyst retention was investigated. Inspection of the foam metal following the first life test revealed significant degradation. Consequently an investigation was conducted to determine the mechanism of degradation and to provide an improved foam metal.

  10. Analysis of regularly perturbed lattices and reaction rate distributions from TIC experiments for X7 lattices

    International Nuclear Information System (INIS)

    Highlights: → We conducted analysis of TIC experiments on regularly perturbed lattice experiments using indigenously developed EXCEL, TRIHEX-FA and HEXPIN code system. → Analysis uses diffusion iterative technique (DIT) method which iteratively adjusts the absorber cell cross sections. → For simulation of dry lattice above the critical moderator height a suitable gamma boundary condition has been used. → The calculated fission rate and activation reaction rate distributions are in good agreement with the experiments. - Abstract: Temporary International Collective (TIC) was established in 1972 by an agreement among seven countries, namely, Bulgaria, Czechoslovakia, Germany, Hungary, Poland, Romania and Union of Soviet Socialist Republics. The main objective of TIC was to provide the experimental data for the reactor physics analysis of water cooled and water moderated power reactors (WWER). Extensive experimental work for different core configurations was carried out by TIC countries to investigate the physics behavior of WWER lattices and the results were published in TIC volumes. In this paper, TIC experiments on regularly perturbed cores have been analyzed as part of the validation of indigenous computer codes, EXCEL, TRIHEX-FA and HEXPIN developed at Light Water Reactors Physics Section, B.A.R.C. The few group homogenized parameters of assembly cell or individual lattice cells were obtained by the hexagonal lattice burn-up code EXCEL and the core diffusion calculations were then performed using hexagonal assembly geometric code TRIHEX-FA and the pin-by-pin diffusion code HEXPIN. A transport-diffusion theory correction to the absorber cell cross section by a diffusion iterative technique (DIT) was used to iteratively adjust the absorber cell cross sections such that the transport leakage into the absorber cell is reproduced by diffusion theory. Neutron-nuclear multi-group cross-section libraries in WIMS/D format in 69/172 energy groups have been released

  11. One-pot synthesis of reduced graphene oxide supported PtCuy catalysts with enhanced electro-catalytic activity for the methanol oxidation reaction

    International Nuclear Information System (INIS)

    The outstanding performance PtCuy (y = 1,2,3) alloy nanoparticles supported on reduced graphene oxide (rGO) have been synthesized by a facile, efficient, one-pot hydrothermal synthesis approach. The as-prepared PtCuy/rGO catalysts are comprehensively characterized by X-ray diffraction, X-ray photoelectron spectroscopy, transmission electron microscopy. Cyclic voltammetry, CO-stripping voltammetry and chronoamperometry results reveal that the PtCuy/rGO catalysts have higher electro-catalytic activity, more negative onset oxidative potential, more excellent tolerance ability for CO poisoning and enhanced stability for the electro-oxidation of methanol compared to pure Pt/rGO. As far as the as-made PtCuy/rGO catalysts are concerned, the PtCu2/rGO exhibits the highest electro-catalytic activity. The mechanism of the promoting effect of Cu on Pt is explained based on the electronic modification effect. The nature of interfacial interactions between the Pt-Cu active metal phase and the rGO supporting materials is crucial to achieving high performance

  12. First-principles quantum-mechanical investigations: The role of water in catalytic conversion of furfural on Pd(111)

    Science.gov (United States)

    Xue, Wenhua; Borja, Miguel Gonzalez; Resasco, Daniel E.; Wang, Sanwu

    2015-03-01

    In the study of catalytic reactions of biomass, furfural conversion over metal catalysts with the presence of water has attracted wide attention. Recent experiments showed that the proportion of alcohol product from catalytic reactions of furfural conversion with palladium in the presence of water is significantly increased, when compared with other solvent including dioxane, decalin, and ethanol. We investigated the microscopic mechanism of the reactions based on first-principles quantum-mechanical calculations. We particularly identified the important role of water and the liquid/solid interface in furfural conversion. Our results provide atomic-scale details for the catalytic reactions. Supported by DOE (DE-SC0004600). This research used the supercomputer resources at NERSC, of XSEDE, at TACC, and at the Tandy Supercomputing Center.

  13. Beryllium-steam interaction experiments and self-sustained reaction studies (integral validation testing)

    International Nuclear Information System (INIS)

    In accordance with the Task Agreement G 81 TT 02 FR, Be-steam interaction experiments were performed in order to obtain experimental data for validation of calculation codes analyzing accident situation involving water coolant ingress into the vacuum chamber of International Thermonuclear Experimental Reactor (ITER). The report describes the experimental facility, specimens used for oxidized beryllium emissivity factor determination and the ITER first wall mock-up used in the experiments on its interaction with steam. Experimental results on Be-emissivity factor after beryllium oxidation versus temperature are given. Four experimental runs of the ITER first wall mock-up interaction with steam were carried out for initial conditions when internal (beryllium) mock-up layer was heated to temperatures of 680, 880 and 1273 K and steam temperature was of 413-423 K. The plots of temperature evolution for beryllium, bronze and stainless steel layers versus time were obtained. Temperature records with 5 s interval are presented. Hydrogen gain in these four experimental runs was measured. The data may be used for computer code validation. No self-sustained Be-steam chemical reaction at temperatures used in the experiments was observed

  14. Optical activity of catalytic elements of hetero-metallic nanostructures

    Science.gov (United States)

    Antosiewicz, Tomasz J.; Apell, S. Peter; Wadell, Carl; Langhammer, Christoph

    2015-05-01

    Interaction of light with metals in the form of surface plasmons is used in a wide range of applications in which the scattering decay channel is important. The absorption channel is usually thought of as unwanted and detrimental to the efficiency of the device. This is true in many applications, however, recent studies have shown that maximization of the decay channel of surface plasmons has potentially significant uses. One of these is the creation of electron-hole pairs or hot electrons which can be used for e.g. catalysis. Here, we study the optical properties of hetero-metallic nanostructures that enhance light interaction with the catalytic elements of the nanostructures. A hybridized LSPR that matches the spectral characteristic of the light source is excited. This LSPR through coupling between the plasmonic elements maximizes light absorption in the catalytic part of the nanostructure. Numerically calculated visible light absorption in the catalytic nanoparticles is enhanced 12-fold for large catalytic disks and by more 30 for small nanoparticles on the order of 5 nm. In experiments we measure a sizable increase in the absorption cross section when small palladium nanoparticles are coupled to a large silver resonator. These observations suggest that heterometallic nanostructures can enhance catalytic reaction rates.

  15. Catalytic activity of Au nanoparticles

    DEFF Research Database (Denmark)

    Larsen, Britt Hvolbæk; Janssens, Ton V.W.; Clausen, Bjerne;

    2007-01-01

    Au is usually viewed as an inert metal, but surprisingly it has been found that Au nanoparticles less than 3–5 nm in diameter are catalytically active for several chemical reactions. We discuss the origin of this effect, focusing on the way in which the chemical activity of Au may change with par......Au is usually viewed as an inert metal, but surprisingly it has been found that Au nanoparticles less than 3–5 nm in diameter are catalytically active for several chemical reactions. We discuss the origin of this effect, focusing on the way in which the chemical activity of Au may change...... with particle size. We find that the fraction of low-coordinated Au atoms scales approximately with the catalytic activity, suggesting that atoms on the corners and edges of Au nanoparticles are the active sites. This effect is explained using density functional calculations....

  16. Experiments on the high temperature graphite and steam reaction under LOCA condition

    International Nuclear Information System (INIS)

    The results of conceptual design activity of ITER (International Thermonuclear Experimental Reactor) gave graphite as a primarily candidate for the plasma facing materials in the first physics phase. In safety analysis of the fusion experimental reactor, release of radioactive tritium and activation product in the plasma-facing materials caused by a loss of coolant accident (LOCA) in a vacuum vessel is one of the severest accident scenarios. It is presumed that loss of coolant flow will generate an extremely high temperature spot, above 1000 degrees C, on plasma-facing components such as armor tiles of the first wall and divertor plates. Thus coolant pipe made of copper will break or melt, then coolant water will blow out as steam into the vacuum vessel. High temperature graphite will react violently with the steam pouring into the vacuum vessel. Then safety analysis necessitate that the reactivity of the graphite materials should be precisely evaluated. To obtain fundamental data for safety analyses considering loss of coolant inside of the vessel, the rate of reaction between high temperature graphite and steam has been experimentally measured between 1000 and 1600 degrees C. For experiments isotopic graphite and C/C composite ones were used. Reaction rate to a unit surface area was measured dividing the weight loss by inner surface area of tube type graphite specimen, and product gases were analyzed by gas-chromatography

  17. Utilisation of gold nanoparticles on amine-functionalised UiO-66 (NH2-UiO-66) nanocrystals for selective tandem catalytic reactions.

    Science.gov (United States)

    Hinde, Christopher S; Webb, William R; Chew, Benny K J; Tan, Hui Ru; Zhang, Wen-Hua; Hor, T S Andy; Raja, Robert

    2016-05-01

    Colloidal deposition of gold nanoparticles (Au NPs) onto NH2-UiO-66 nanocrystals has been demonstrated with the resulting hybrid catalyst proving robust and versatile for one-pot, heterogeneous conversions involving the selective oxidation of primary alcohols in tandem with Knoevenagel condensation reactions. Within these systems, structure-property correlations have been established to confirm that the active sites for the oxidation and condensation reactions are intrinsically correlated with the Au NPs and pendant amine groups respectively. PMID:27104291

  18. Metallic Sn spheres and SnO2@C core-shells by anaerobic and aerobic catalytic ethanol and CO oxidation reactions over SnO2 nanoparticles

    Science.gov (United States)

    Kim, Won Joo; Lee, Sung Woo; Sohn, Youngku

    2015-08-01

    SnO2 has been studied intensely for applications to sensors, Li-ion batteries and solar cells. Despite this, comparatively little attention has been paid to the changes in morphology and crystal phase that occur on the metal oxide surface during chemical reactions. This paper reports anaerobic and aerobic ethanol and CO oxidation reactions over SnO2 nanoparticles (NPs), as well as the subsequent changes in the nature of the NPs. Uniform SnO2@C core-shells (10 nm) were formed by an aerobic ethanol oxidation reaction over SnO2 NPs. On the other hand, metallic Sn spheres were produced by an anaerobic ethanol oxidation reaction at 450 °C, which is significantly lower than that (1200 °C) used in industrial Sn production. Anaerobic and aerobic CO oxidation reactions were also examined. The novelty of the methods for the production of metallic Sn and SnO2@C core-shells including other anaerobic and aerobic reactions will contribute significantly to Sn and SnO2-based applications.

  19. Catalytic reforming process

    Energy Technology Data Exchange (ETDEWEB)

    Absil, R.P.; Huss, A. Jr.; McHale, W.D.; Partridge, R.D.

    1989-06-13

    This patent describes a catalytic reforming process which comprises contacting a naphtha range feed with a low acidity extrudate comprising an intermediate and/or a large pore acidic zeolite bound with a low acidity refractory oxide under reforming conditions to provide a reaction product of increased aromatic content, the extrudate having been prepared with at least an extrusion-facilitating amount of a low acidity refractory oxide in colloidal form and containing at least one metal species selected from the platinum group metals.

  20. Influence of Reaction Conditions on the Catalytic Oxidation of Cyclohexene with Molecular Oxygen Using a Series of Keggin-Type Polyoxometalate

    Directory of Open Access Journals (Sweden)

    Ramyah Radman

    2015-12-01

    Full Text Available A series of keggin-type polyoxometalatesnamely; H3PMo12O40,H3PW12O40, Fe1.5PW12O40 and Co1.5PW12O40 were prepared, characterized and tested for the oxidation of cyclohexene by molecular oxygen in acetonitrile medium. The oxidation gives 2-cyclohexen-1-ol, 2-cyclohexen-1-one and cyclohexene oxide,however, 2-cyclohexen-1-one was the major product.TheCo1.5PW12O40catalyst showed the highest catalytic activity for the oxidation reactionand it was chose to study the effect ofvaryingO2 pressure, time, temperature and catalyst weight. The highest percentage of cyclohexen econ version and selectivity of the major product 2-cyclohexen-1-one was obtained at 5bar of O2 pressure, 4h, 70 oC, and 900mg of Co1.5PW12O40 catalyst.

  1. Amphibole reaction rim textures and mineralogy from the 2006 eruption of Augustine Volcano, Alaska: Nature vs. experiment

    Science.gov (United States)

    Henton, S.; Larsen, J. F.; Coombs, M. L.

    2011-12-01

    Augustine Volcano forms a small island located in Alaska's Cook Inlet, approximately 180 miles southwest of Anchorage. The 2006 eruption began January 11, 2006, and evolved from an initial phase of explosive activity, through continuous and effusive phases, ending approximately mid-March 2006. We present data on the textural and mineralogical make-up of amphibole reaction rims from 2006 andesites from Augustine. Naturally formed reaction rims are compared to rims formed through decompression and heating experiments. Amphiboles make up less than 1 modal % of most samples. However, variations in composition and texture help to explain pre-and syn-eruptive magma histories. The Augustine 2006 amphiboles contain a mixture of rimmed and unrimmed grains. In order of decreasing abundance (by tally), the dominant phases in reaction rims are orthopyroxene, oxides, plagioclase, and clinopyroxene. Most amphibole reaction rims are between 1- 40 microns in thickness. Thicker rims (> 40 microns) were primarily erupted in the later effusive phase of the eruption. In general, the thickest reactions rims (> 60 microns average thickness) contain coarser individual reaction rim grains (with feret diameters of 15-50 microns). Reaction rims with average thickness of less than 60 microns tend to contain finer reaction rim grains (with feret diameters of 10 microns or less). Some reactions rims show a coarsening of rim grains across the rim, from the amphibole boundary to the glass boundary. Preliminary results show no systematic changes in the aspect ratios of reaction rim grains, either across the rim, or between the different rims. Some rims show a decrease in the An content of plagioclase across the rim, from the amphibole boundary to the glass boundary. Reaction rim textures and mineralogy are complex and suggest that multiple forcing factors (including heating and decompression) were responsible for their formation. This study will compare these natural reaction rims to those formed

  2. Dependence of catalytic properties of Al/Fe2O3 thermites on morphology of Fe2O3 particles in combustion reactions

    Science.gov (United States)

    Zhao, Ningning; He, Cuicui; Liu, Jianbing; Gong, Hujun; An, Ting; Xu, Huixiang; Zhao, Fengqi; Hu, Rongzu; Ma, Haixia; Zhang, Jinzhong

    2014-11-01

    Three Fe2O3 particle samples with the same crystal structure but different morphologies were prepared by the hydrothermal method and then combined with Al nanoparticles to produce Al/Fe2O3 thermites using ultrasonic mixing. The properties of Fe2O3 and Al/Fe2O3 were studied using a combination of experimental techniques including scanning electron microscopy (SEM), energy dispersive spectrometer (EDS), X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), and differential scanning calorimetry (DSC). The influences of the three Al/Fe2O3 thermites on the combustion properties of the AP/HTPB (ammonium perchlorate/hydroxyl-terminated polybutadiene) composite propellant were investigated in comparison to those of Fe2O3. The results show that the Al/Fe2O3 thermites are better than Fe2O3 in enhancing the combustion performance of AP/HTPB. Furthermore, the surface area, which depends on size and mophology, of Fe2O3 particles was found to play a vital role in improving the burning rate of the thermites-containing propellant formulation, with the smallest particles with the largest surface-to-volume (S/V) ratio performing the best. The enhanced catalytic property of the granular-shape Fe2O3 and the corresponding thermite is attributed to the large specific surface area of Fe2O3. The different thermal behaviors of these three superthemites were supposed to be attributed to the surface site of Fe2O3 particles. This work provides a better understanding on the catalytic properties of thermites that are important for combustion applications.

  3. Catalytic properties of niobium compounds

    International Nuclear Information System (INIS)

    The catalytic activity and selectivity of niobium compounds including oxides, salts, organometallic compounds and others are outlined. The application of these compounds as catalysts to diversified reactions is reported. The nature and action of niobium catalysts are characteristic and sometimes anomalous, suggesting the necessity of basic research and the potential use as catalysts for important processes in the chemical industry. (Author)

  4. Performance of a Novel Hydrophobic Mesoporous Material for High Temperature Catalytic Oxidation of Naphthalene

    Directory of Open Access Journals (Sweden)

    Guotao Zhao

    2014-01-01

    Full Text Available A high surface area, hydrophobic mesoporous material, MFS, has been successfully synthesized by a hydrothermal synthesis method using a perfluorinated surfactant, SURFLON S-386, as the single template. N2 adsorption and TEM were employed to characterize the pore structure and morphology of MFS. Static water adsorption test indicates that the hydrophobicity of MFS is significantly higher than that of MCM-41. XPS and Py-GC/MS analysis confirmed the existence of perfluoroalkyl groups in MFS which led to its high hydrophobicity. MFS was used as a support for CuO in experiments of catalytic combustion of naphthalene, where it showed a significant advantage over MCM-41 and ZSM-5. SEM was helpful in understanding why CuO-MFS performed so well in the catalytic combustion of naphthalene. Experimental results indicated that MFS was a suitable support for catalytic combustion of large molecular organic compounds, especially for some high temperature catalytic reactions when water vapor was present.

  5. Effect the conditions of the acid-thermal modification of clinoptilolite have on the catalytic properties of palladium-copper complexes anchored on it in the reaction of carbon monoxide oxidation

    Science.gov (United States)

    Rakitskaya, T. L.; Kiose, T. A.; Ennan, A. A.; Golubchik, K. O.; Oleksenko, L. P.; Gerasiova, V. G.

    2016-06-01

    The dependence of the physicochemical and structural-adsorption properties of natural and acid-thermal modified clinoptilolite, and of Pd(II)-Cu(II) catalysts based on them, on the duration of acid-thermal modification is investigated. The samples under study are described via XRD and thermal gravimetric (DTG and DTA) analysis, IR, DR UV-Vis, EPR spectroscopy, and water vapor adsorption. Values of both the specific surface area ( S sp) and pH of aqueous suspensions are determined. The resulting catalysts are tested in the reaction of low-temperature carbon monoxide oxidation with air oxygen. A conclusion is drawn about the nature of surface bimetallic Pd(II)-Cu(II) complexes. The greatest catalytic activity is shown by complexes based on clinoptilolite and modified with 3 M HNO3 for 0.5 and 1 h.

  6. 咪唑类离子液体及其催化有机不对称反应%Imidazolium ionic liquids and catalytic asymmetric reactions of organic

    Institute of Scientific and Technical Information of China (English)

    姜红波

    2011-01-01

    离子液体作为一种新型绿色溶剂,具有许多独特的物理化学性质,近年来逐渐被人们所认知,并发现可用在许多重要领域.本文简单介绍离子液体及其特点,重点介绍在咪唑类离子液体中典型的不对称加氢反应、不对称Michael加成反应、不对称Aldol反应、不对称烯丙基反应和不对称氟化反应.%As a new type of green solvents, ionic liquids has many unique physical and chemical properties.It has been perceived and found in many important areas available in recent years.This article briefly describes the types and characteristics of ionic liquids, focusing on the typical asymmetric hydrogenation reaction, asymmetric Michael addition reaction, asymmetric Aldol reaction, asymmetric allylation reaction and asymmetric fluorination reaction in imidazolium ionic liquids.

  7. Kinetic catalytic studies of scorpion's hemocyanin

    International Nuclear Information System (INIS)

    Hemocyanins are copper proteins which function as oxygen carriers in the haemolymph of Molluscs and Arthropods. They possess enzymatic properties: peroxidatic and catalatic activities, although they have neither iron nor porphyrin ring at the active site. The kinetics of the catalytic reaction is described. The reaction of superoxide anion with hemocyanin has been studied using pulse radiolysis at pH 9. The catalytic rate constant is 3.5 X 107 mol-1.l.s-1

  8. Metallic Sn spheres and SnO2@C core-shells by anaerobic and aerobic catalytic ethanol and CO oxidation reactions over SnO2 nanoparticles

    OpenAIRE

    Won Joo Kim; Sung Woo Lee; Youngku Sohn

    2015-01-01

    SnO2 has been studied intensely for applications to sensors, Li-ion batteries and solar cells. Despite this, comparatively little attention has been paid to the changes in morphology and crystal phase that occur on the metal oxide surface during chemical reactions. This paper reports anaerobic and aerobic ethanol and CO oxidation reactions over SnO2 nanoparticles (NPs), as well as the subsequent changes in the nature of the NPs. Uniform SnO2@C core-shells (10 nm) were formed by an aerobic eth...

  9. Influence of catalytic activity and reaction conditions on the product distribution in coal liquefaction; Sekitan ekikayu no seiseibutsu bunpu ni taisuru shokubai kassei oyobi hanno joken no eikyo

    Energy Technology Data Exchange (ETDEWEB)

    Hasuo, H.; Sakanishi, K.; Mochida, I. [Kyushu University, Fukuoka (Japan). Institute of Advanced Material Study

    1996-10-28

    The NiMo sulfide supported on Ketjen Black (KB) was more effective and yielded lighter oil products containing light fractions with their boiling point below 300{degree}C during the two stage liquefaction combining low temperature and high temperature hydrogenation the conventional NiMo/alumina catalyst and FeS2 catalyst. Although the NiMo/alumina yielded increased oil products during the two stage liquefaction, the lighter oil fractions did not increase and the heavier fractions increased mainly. This suggests that the hydrogenation of aromatic rings and successive cleavage of the rings are necessary for producing the light oil, which is derived from the sufficient hydrogenation of aromatic rings using catalysts. For the two stage reaction with NiMo/KB catalyst, it was considered that sufficient hydrogen was directly transferred to coal molecules at the first stage of the low temperature reaction, which promoted the solubilization of coal and the successive hydrogenation at the high temperature reaction. Thus, high activity of the catalyst must be obtained. It is expected that further high quality distillates can be produced through the optimization of catalysts and solvents at the two stage reaction. 1 ref., 4 figs., 1 tab.

  10. Cross Sections for Neutron-induced Reactions on Actinide Targets Extracted from Surrogate Experiments: A Status Report

    Energy Technology Data Exchange (ETDEWEB)

    Escher, J E; Burke, J T; Dietrich, F S; Lesher, S R; Scielzo, N D; Thompson, I J; Younes, W

    2009-10-01

    The Surrogate nuclear reactions method, an indirect approach for determining cross sections for compound-nuclear reactions involving difficult-to-measure targets, is reviewed. Focusing on cross sections for neutron-induced reactions on actinides, we review the successes of past and present applications of the method and assess its uncertainties and limitations. The approximations used in the analyses of most experiments work reasonably well for (n,f) cross sections for neutron energies above 1-2 MeV, but lead to discrepancies for low-energy (n,f) reactions, as well as for (n,{gamma}) applications. Correcting for some of the effects neglected in the approximate analyses leads to improved (n,f) results. We outline steps that will further improve the accuracy and reliability of the Surrogate method and extend its applicability to reactions that cannot be approached with the present implementation of the method.

  11. Data discrepancies in and new experiments for D+D, D+T, and T+T fusion reactions

    International Nuclear Information System (INIS)

    The purpose of this work is to investigate the accuracy of the basic fusion reaction data for the reactions T(d,n)4He, T(t,2n)4He, D(d,n)3He, and D(d,p)T, and to describe an elaborate experiment in progress at the Los Alamos Scientific Laboratory to remeasure the cross sections with improved accuracy

  12. Experiment E89-044 on the Quasielastic 3He(e,e'p) Reaction at Jefferson Laboratory

    Energy Technology Data Exchange (ETDEWEB)

    E. Penel-Nottaris

    2004-07-07

    The Jefferson Lab Hall A E89-044 experiment has measured the 3He(e,e'p) reaction cross-sections. The extraction of the longitudinal and transverse response functions for the two-body break-up 3He(e,e'p)d reaction in parallel kinematics allows the study of the bound proton electromagnetic properties inside the 3He nucleus and the involved nuclear mechanisms beyond plane wave approximations.

  13. Catalytic Enantioselective Functionalization of Unactivated Terminal Alkenes.

    Science.gov (United States)

    Coombs, John R; Morken, James P

    2016-02-01

    Terminal alkenes are readily available functional groups which appear in α-olefins produced by the chemical industry, and they appear in the products of many contemporary synthetic reactions. While the organic transformations that apply to alkenes are amongst the most studied reactions in all of chemical synthesis, the number of reactions that apply to nonactivated terminal alkenes in a catalytic enantioselective fashion is small in number. This Minireview highlights the cases where stereocontrol in catalytic reactions of 1-alkenes is high enough to be useful for asymmetric synthesis. PMID:26764019

  14. Radiation chemical effects in experiments to study the reaction of glass in an environment of gamma-irradiated air, groundwater, and tuff

    Energy Technology Data Exchange (ETDEWEB)

    Van Konynenburg, R.A.

    1986-05-02

    The results of experiments performed by John K. Bates et al. on the reaction of nuclear waste glass with a gamma-irradiated 90{sup 0}C aqueous solution were analyzed using theory developed from past research in radiation chemistry. The aqueous solution they used is similar to what would be expected in a water-saturated environment in a nuclear waste repository in tuff. The purpose of our study was to develop an understanding of the radiation-chemical processes that occurred in the Bates et al. experiments so the results could be applied to the design and performance analysis of a proposed repository in unsaturated tuff in Nevada. For the Bates et al. experiments at the highest dose (269 Mrad), which originally contained about 16 ml of "equilibrated" water taken from Nevada Test Site Well J-13 and 5.4 ml of air, we predicted that water decomposition to H{sub 2} and O{sub 2} would produce a pressure increase of at least 1.0 MPa at 20{sup 0}C. We also predicted that nitrogen fixation from the air would occur, producing an increase of 1.6 x 10{sup -4} M in total fixed nitrogen concentration in solution. In addition, an equimolar production of H{sup +} would occur, which would be buffered by the HCO{sub 3}{sup -} in the water. The fixed nitrogen in solution was predicted to be present as NO{sub 2}{sup -} and NO{sub 3}{sup -} with the ratio influenced by the presence of materials catalytic to the decomposition of H{sub 2}O{sub 2}. We found reasonable agreement between our predictions and the observations of Bates et al., where comparisons were possible. We apply the results to the proposed Nevada repository to the degree possible, given the different expected conditions.

  15. Calculations of chemisorption and the elementary acts of catalytic reactions within the framework of a cluster model. XI. Dehydration of ethyl alcohol

    Energy Technology Data Exchange (ETDEWEB)

    Senchenya, I.N.; Mikheikin, I.D.; Zhidomirov, G.M.; Kazanskii, V.B.

    1980-09-01

    Within the framework of the CNDO/BW method and of a cluster model, this article discusses the energetics of the intermediate structures in the dehydration of ethyl alcohol over alumino-silicate catalysts. It is shown that during coordination there ia a selective weakening of the C - O and C..beta.. - H bonds, which promotes the dehydration of ethyl alchol to an unsaturated hydrocarbon. The calculation argues in support of the possibility of a synchronous mechanism of the reaction in question.

  16. Recent Advances on Electro-Oxidation of Ethanol on Pt- and Pd-Based Catalysts: From Reaction Mechanisms to Catalytic Materials

    OpenAIRE

    Ye Wang; Shouzhong Zou; Wen-Bin Cai

    2015-01-01

    The ethanol oxidation reaction (EOR) has drawn increasing interest in electrocatalysis and fuel cells by considering that ethanol as a biomass fuel has advantages of low toxicity, renewability, and a high theoretical energy density compared to methanol. Since EOR is a complex multiple-electron process involving various intermediates and products, the mechanistic investigation as well as the rational design of electrocatalysts are challenging yet essential for the desired complete oxidation to...

  17. Green synthesis of CuO nanoparticles by aqueous extract of Anthemis nobilis flowers and their catalytic activity for the A³ coupling reaction.

    Science.gov (United States)

    Nasrollahzadeh, Mahmoud; Sajadi, S Mohammad; Rostami-Vartooni, Akbar

    2015-12-01

    CuO nanoparticles (NPs) were prepared by Anthemis nobilis flowers extract as a reducing and stabilizing agent and employed in catalyzing an aldehyde-amine-alkyne coupling reaction. The synthesized CuO NPs was characterized by SEM, EDS, XRD, FT-IR and UV-visible techniques. A diverse range of propargylamines were obtained in a good to high yield. Furthermore, the separation and reuse of CuO NPs was very simple, effective and economical. PMID:26291574

  18. A computational study of detoxification of lewisite warfare agents by British anti-lewisite: catalytic effects of water and ammonia on reaction mechanism and kinetics.

    Science.gov (United States)

    Sahu, Chandan; Pakhira, Srimanta; Sen, Kaushik; Das, Abhijit K

    2013-04-25

    trans-2-Chlorovinyldichloroarsine (lewisite, L agent, Lew-I) acts as a blistering agents. British anti-lewisite (BAL, 2,3-dimercaptopropanol) has long been used as an L-agent antidote. The main reaction channels for the detoxification proceed via breaking of As-Cl bonds and formation of As-S bonds, producing stable, nontoxic ring product [(2-methyl-1,3,2-dithiarsolan-4-yl)methanol]. M06-2X/GENECP calculations have been carried out to establish the enhanced rate of detoxification mechanism in the presence of NH3 and H2O catalysts in both gas and solvent phases, which has been modeled by use of the polarized continuum model (PCM). In addition, natural bond orbital (NBO) and atoms in molecules (AIM) analysis have been performed to characterize the intermolecular hydrogen bonding in the transition states. Transition-state theory (TST) calculation establishes that the rates of NH3-catalyzed (2.88 × 10(-11) s(-1)) and H2O-catalyzed (2.42 × 10(-11) s(-1)) reactions are reasonably faster than the uncatalyzed detoxification (5.44 × 10(-13) s(-1)). The results obtained by these techniques give new insight into the mechanism of the detoxification process, identification and thermodynamic characterization of the relevant stationary species, the proposal of alternative paths on modeled potential energy surfaces for uncatalyzed reaction, and the rationalization of the mechanistic role played by catalysts and solvents. PMID:23540856

  19. Shock tube experiments on nitromethane and Promotion of chemical reactions by non-thermal plasma

    Energy Technology Data Exchange (ETDEWEB)

    Seljeskog, Morten

    2002-06-01

    This dissertation was undertaken to study two different subjects both related to molecular decomposition by applying a shock tube and non-thermal plasma to decompose selected hydrocarbons. The first approach to molecular decomposition concerned thermal decomposition and oxidation of highly diluted nitromethane (NM) in a shock tube. Reflected shock tube experiments on NM decomposition, using mixtures of 0.2 to 1.5 vol% NM in nitrogen or argon were performed over the temperature range 850-1550 K and pressure range 190-900 kPa, with 46 experiments diluted in nitrogen and 44 diluted in argon. By residual error analysis of the measured decomposition profiles it was found that NM decomposition (CH{sub 3}NO{sub 2} + M {yields} CH{sub 3} + NO{sub 2} + M, where M = N{sub 2} /Ar) corresponds well to a law of first order. Arrhenius expressions corresponding to NM diluted either in N{sub 2} or in Ar were found as k{sub N2} = 10{sup 17.011} * exp(- 182.6 kJ/mole / R*T) and k{sub Ar} = 10{sup 17.574}*exp(-207 kJ/mole / R*T ) , respectively. A new reaction mechanism was then proposed, based on new experimental data for NM decomposition both in Ar and N{sub 2} and on three previously developed mechanisms. The new mechanism predicts well the decomposition of NM diluted in both N{sub 2} and Ar within the pressure and temperature range covered by the experiments. In parallel to, and following the decomposition experiments, oxidative experiments on the ignition delay times of NM/O{sub 2}/Ar mixtures were investigated over high temperature and low to high pressure ranges. These experiments were carried out with eight different mixtures of gaseous NM and oxygen diluted in argon, with pressures ranging between 44.3-600 kPa, and temperatures ranging between 842-1378 K. The oxidation experiments were divided into different categories according to the type of decomposition signals achieved. For signals with and without emission, the apparent quasi

  20. Cold-cap reactions in vitrification of nuclear waste glass: experiments and modeling

    International Nuclear Information System (INIS)

    Cold-cap reactions are multiple overlapping reactions that occur in the waste-glass melter during the vitrification process when the melter feed is being converted to molten glass. In this study, we used differential scanning calorimetry (DSC) to investigate cold-cap reactions in a high-alumina high-level waste melter feed. To separate the reaction heat from both sensible heat and experimental instability, we employed the run/rerun method, which enabled us to define the degree of conversion based on the reaction heat and to estimate the heat capacity of the reacting feed. Assuming that the reactions are nearly independent and can be approximated by the nth order kinetics, we obtained the kinetic parameters using the Kissinger method combined with least squares analysis. The resulting mathematical simulation of the cold-cap reactions provides a key element for the development of an advanced cold-cap model

  1. Catalytic Oxidized Reaction of Paraffin Wax Based on BP Neural Network%基于BP神经网络的石蜡催化氧化反应的研究

    Institute of Scientific and Technical Information of China (English)

    黄玮; 丛玉凤; 郭大鹏

    2012-01-01

    The oxidized wax was prepared by catalytic oxidized reaction of paraffin wax which used BP neural network to build mathematical model of acid value and saponification value influenced by the amount of reactive catalyst and accessory ingredient, airflow rate, reaction temperature and time, and utilized the model of neutral network to calculate the technology condition of preparing oxidized wax through catalyzing and oxidizing paraffin wax. Consequently, optimum technology conditions were gained in order to achieve the objective of reducing experimental number of times.%在石蜡催化氧化反应制备氧化蜡的研究中,利用BP神经网络建立反应催化剂用量、助剂用量、空气流量、反应温度和反应时间对酸值和皂化值影响的数学模型,并利用该神经网络模型对石蜡催化氧化制备氧化蜡的工艺条件进行预测,从而获得最优工艺条件,达到缩短实验次数的目的.

  2. Methanol conversion to light olefins over nanostructured CeAPSO-34 catalyst: Thermodynamic analysis of overall reactions and effect of template type on catalytic properties and performance

    International Nuclear Information System (INIS)

    Graphical abstract: In this research nanostructured CeAPSO-34 was synthesized to explore the effect of TEAOH and morpholine on its physiochemical properties and MTO performance. Prepared catalysts were characterized with XRD, FESEM, BET, FTIR and NH3-TPD techniques. The results indicated that the nature of the template determines the physiochemical properties of CeAPSO-34 due to different rate of crystal growth. The catalyst obtained by using morpholine showed longer life time as well as sustaining light olefins selectivity at higher values. Furthermore, a comprehensive thermodynamic analysis of overall reactions network was carried out to address the major channels of methanol to olefins conversion. - Highlights: • Introduction of Ce into SAPO-34 framework. • Comparison of CeAPSO-34 synthesized using morpholine and TEAOH. • The nature of the template determines the physiochemical properties of CeAPSO-34. • Morpholine enhances catalyst lifetime in MTO process. • Presenting a complete reaction network for MTO process. - Abstract: TEAOH and morpholine were employed in synthesis of nanostructured CeAPSO-34 molecular sieve and used in methanol to olefins conversion. Prepared samples were characterized by XRD, FESEM, EDX, BET, FTIR and NH3-TPD techniques. XRD patterns reflected the higher crystallinity of the catalyst synthesized with morpholine. The FESEM results indicated that the nature of the template determines the morphology of nanostructured CeAPSO-34 due to different rate of crystal growth. There was a meaningful difference in the strength of both strong and weak acid sites for CeAPSO-34 catalysts synthesized with TEAOH and morpholine templates. The catalyst synthesized with morpholine showed higher desorption temperature of both weak and strong acid sites evidenced by NH3-TPD characterization. The catalyst obtained using morpholine template had the longer lifetime and sustained desired light olefins at higher values. A comprehensive thermodynamic

  3. Kinetic Modeling of Complex Catalytic Reactions Modélisation cinétique des réactions catalytiques complexes

    Directory of Open Access Journals (Sweden)

    Froment G. F.

    2006-11-01

    Full Text Available The paper deals with hydrocracking on metal-loaded zeolites. A fundamental approach is presented in which the detailed reaction network of the feed components of a complex feedstock is retained to a maximum extent. The kinetics are developed in terms of the elementary steps and single events involved in the reactions. Plausible assumptions and thermodynamic constraints limit the number of kinetic parameters. These do not depend on the chain length of the hydrocarbons and are not affected by the feed composition. Certainly, chemical analysis still imposes a certain degree of lumping of components and reaction networks, but not to the extent reflected by present day models. L'article traite de l'hydrocraquage sur des zéolites chargés en métaux. Dans l'approche fondamentale qui est présentée, le réseau de réaction des composants d'une charge complexe est retenu au maximum. La cinétique est établie en suivant pas à pas le déroulement et les étapes élémentaires des réactions. Des hypothèses plausibles et des contraintes thermodynamiques limitent le nombre de paramètres cinétiques. Ceux-ci ne dépendent pas de la longueur de la chaîne des hydrocarbures et ne sont pas affectés par la composition de la charge. L'analyse chimique impose bien sûr encore un certain agrégat des composants et des réseaux de réaction, mais moins que ne reflètent les modèles actuels.

  4. Fundamental studies of the mechanism of catalytic reactions with catalysts effective in the gasification of carbon solids and the oxidative coupling of methane. Quarterly report, April 1, 1994--June 30, 1994

    Energy Technology Data Exchange (ETDEWEB)

    Iglesia, E.; Perry, D.L.; Heinemann, H.

    1994-06-01

    Catalytic gasification work has been completed and no other work is planned in the general area of catalytic gasification of coals and chars has operated without a post-doctoral fellow because of budget limitations during the first two quarters of FY1994. Dr. S. Sundararajan joined the group in April 1994 and will be assigned to the project throughout the remaining of the fiscal year. Results published by Hamakawa, et al. in The Journal of the Electrochemical Society have confirmed the concept of methane coupling via a membrane reactor. These findings confirm our previous conclusion that thinner membranes and increased surface activity for C-H bond activation at low temperatures are required in order to reach commercially attractive rates of reaction. The initial analysis of a theoretical model comparing the membrane and cyclic processes has been completed. The results indicate that perovskite membranes on the order of 50 microns will be needed for the membrane operation to be superior to a cyclic one. Two techniques, laser ablation and spin-coating/sol-gel chemistry are being tried to prepare the thin membranes described above. Studies of the magnetochemical properties of the calcium-nickel-potassium oxide powdered catalysts have been concluded and a manuscript describing the work has been completed. Synchrotron x-ray fluorescence microprobe data for calcium-nickel-potassium films have been analyzed and an abstract of the results has been submitted for presentation at the Fall Meeting of the Materials Research Society. Initial films of strontium-zirconium oxide, using yttria-stabilized zirconia as a buffer layer, have been fabricated using pulsed laser deposition. X-ray diffraction data have been obtained for several of the strontium-zirconium-yttrium oxide films.

  5. One-pot synthesis of monodisperse palladium-copper nanocrystals supported on reduced graphene oxide nanosheets with improved catalytic activity and methanol tolerance for oxygen reduction reaction

    Science.gov (United States)

    Lv, Jing-Jing; Li, Shan-Shan; Wang, Ai-Jun; Mei, Li-Ping; Feng, Jiu-Ju; Chen, Jian-Rong; Chen, Zhaojiang

    2014-12-01

    Monodisperse bimetallic alloyed palladium-copper nanocrystals are uniformly supported on reduced graphene oxide nanosheets by a one-pot solvothermal strategy, with an average size of 6.81 nm. As a result, the as-prepared nanocomposites have the enlarged electrochemically active surface area (49.2 m2 g-1), and display the improved electrocatalytic performance and high methanol-tolerance ability for oxygen reduction reaction in alkaline media, compared with commercial Pd black and RGOs. Those RGOs-supporting Pd-Cu alloys would have potential applications in fuel cells.

  6. Update: An efficient synthesis of poly(ethylene glycol)-supported iron(II) porphyrin using a click reaction and its application for the catalytic olefination of aldehydes

    KAUST Repository

    Chinnusamy, Tamilselvi R.

    2012-05-09

    The facile synthesis of polyethylene glycol (PEG)-immobilized iron(II) porphyrin using a copper-catalyzed azide-alkyne [3+2] cycloaddition "click" reaction is reported. The prepared complex 5 (PEG-C 51H 39FeN 7O) was found to be an efficient catalyst for the selective olefination of aldehydes with ethyl diazoacetate in the presence of triphenylphosphine, and afforded excellent olefin yields with high (E) selectivities. The PEG-supported catalyst 5 was readily recovered by precipitation and filtration, and was recycled through ten runs without significant activity loss. Copyright © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  7. Enhancing communication about paediatric medicines: lessons from a qualitative study of parents' experiences of their child's suspected adverse drug reaction.

    Directory of Open Access Journals (Sweden)

    Janine Arnott

    Full Text Available BACKGROUND: There is little research on parents' experiences of suspected adverse drug reactions in their children and hence little evidence to guide clinicians when communicating with families about problems associated with medicines. OBJECTIVE: To identify any unmet information and communication needs described by parents whose child had a suspected adverse drug reaction. METHODS: Semi-structured qualitative interviews with parents of 44 children who had a suspected adverse drug reaction identified on hospital admission, during in-patient treatment or reported by parents using the Yellow Card Scheme (the UK system for collecting spontaneous reports of adverse drug reactions. Interviews were conducted face-to-face or by telephone; most interviews were audiorecorded and transcribed. Analysis was informed by the principles of the constant comparative method. RESULTS: Many parents described being dissatisfied with how clinicians communicated about adverse drug reactions and unclear about the implications for their child's future use of medicines. A few parents felt that clinicians had abandoned their child and reported refusing the use of further medicines because they feared a repeated adverse drug reaction. The accounts of parents of children with cancer were different. They emphasised their confidence in clinicians' management of adverse drug reactions and described how clinicians prospectively explained the risks associated with medicines. Parents linked symptoms to medicines in ways that resembled the established reasoning that clinicians use to evaluate the possibility that a medicine has caused an adverse drug reaction. CONCLUSION: Clinicians' communication about adverse drug reactions was poor from the perspective of parents, indicating that improvements are needed. The accounts of parents of children with cancer indicate that prospective explanation about adverse drug reactions at the time of prescription can be effective. Convergence

  8. Phosphorus/sulfur Co-doped porous carbon with enhanced specific capacitance for supercapacitor and improved catalytic activity for oxygen reduction reaction

    Science.gov (United States)

    Zhou, Yao; Ma, Ruguang; Candelaria, Stephanie L.; Wang, Jiacheng; Liu, Qian; Uchaker, Evan; Li, Pengxi; Chen, Yongfang; Cao, Guozhong

    2016-05-01

    Phosphorus (P)/sulfur (S) co-doped porous carbon derived from resorcinol and furaldehyde are synthesized through one-step sol-gel processing with the addition of phosphorus pentasulfide as P and S source followed with freeze-drying and pyrolysis in nitrogen. The P/S co-doping strategy facilitates the pore size widening both in micropore and mesopore regions, together with the positive effect on the degree of graphitization of porous carbon through elimination of amorphous carbon through the formation and evaporation of carbon disulfide. As an electrode for supercapacitor application, P/S co-doped porous carbon demonstrates 43.5% improvement on specific capacitance of the single electrode compared to pristine porous carbon in organic electrolyte at a current of 0.5 mA due to the P-induced pseudocapacitive reactions. As for electrocatalytic use, promoted electrocatalytic activity and high resistance to crossover effects of oxygen reduction reaction (ORR) in alkaline media are observed after the introduction of P and S into porous carbon. After air activation, the specific capacitance of the single electrode of sample PS-pC reaches up to 103.5 F g-1 and an improved oxygen reduction current density.

  9. Recent Advances on Electro-Oxidation of Ethanol on Pt- and Pd-Based Catalysts: From Reaction Mechanisms to Catalytic Materials

    Directory of Open Access Journals (Sweden)

    Ye Wang

    2015-09-01

    Full Text Available The ethanol oxidation reaction (EOR has drawn increasing interest in electrocatalysis and fuel cells by considering that ethanol as a biomass fuel has advantages of low toxicity, renewability, and a high theoretical energy density compared to methanol. Since EOR is a complex multiple-electron process involving various intermediates and products, the mechanistic investigation as well as the rational design of electrocatalysts are challenging yet essential for the desired complete oxidation to CO2. This mini review is aimed at presenting an overview of the advances in the study of reaction mechanisms and electrocatalytic materials for EOR over the past two decades with a focus on Pt- and Pd-based catalysts. We start with discussion on the mechanistic understanding of EOR on Pt and Pd surfaces using selected publications as examples. Consensuses from the mechanistic studies are that sufficient active surface sites to facilitate the cleavage of the C–C bond and the adsorption of water or its residue are critical for obtaining a higher electro-oxidation activity. We then show how this understanding has been applied to achieve improved performance on various Pt- and Pd-based catalysts through optimizing electronic and bifunctional effects, as well as by tuning their surface composition and structure. Finally we point out the remaining key problems in the development of anode electrocatalysts for EOR.

  10. Development of novel catalytically active polymer-metal-nanocomposites based on activated foams and textile fibers

    Science.gov (United States)

    Domènech, Berta; Ziegler, Kharla K.; Carrillo, Fernando; Muñoz, Maria; Muraviev, Dimitri N.; Macanás, Jorge

    2013-05-01

    In this paper, we report the intermatrix synthesis of Ag nanoparticles in different polymeric matrices such as polyurethane foams and polyacrylonitrile or polyamide fibers. To apply this technique, the polymer must bear functional groups able to bind and retain the nanoparticle ion precursors while ions should diffuse through the matrix. Taking into account the nature of some of the chosen matrices, it was essential to try to activate the support material to obtain an acceptable value of ion exchange capacity. To evaluate the catalytic activity of the developed nanocomposites, a model catalytic reaction was carried out in batch experiments: the reduction of p-nitrophenol by sodium borohydride.

  11. Correlation Models for Light Olefin Yields from Catalytic Pyrolysis of Petroleum Residue

    Institute of Scientific and Technical Information of China (English)

    DongXiaoli; MengXianghai; GaoJinsen; XuChunming

    2005-01-01

    Correlation models for light olefin yields from residue catalytic pyrolysis are studied. Experiments are carried out in a confined fluidized bed reactor for Daqing (China) atmospheric residue catalytic pyrolysis over LCM-5 pyrolyzing catalyst. The influences of reaction temperature, residence time and the weight ratios of catalyst-to-oil and steam-to-oil on light olefin yields are researched. Correlation models for light olefin yields are established, and the model parameters obtained, with the least square method. Results for error analysis and the F-statistical test show that the correlation models have high calculation precision.

  12. Reaction to the Special Issue on Centralizing the Experiences of LGB People of Color in Counseling Psychology

    Science.gov (United States)

    Zea, Maria Cecilia

    2010-01-01

    This reaction article comments on the Major Contribution "Centralizing the Experiences of LGB People of Color in Counseling Psychology." The content analysis of the published literature on lesbian, gay, and bisexual (LGB) people of color from 1998 to 2007 provides much-needed information that will help psychologists set future research agendas and…

  13. A Multistep Organocatalysis Experiment for the Undergraduate Organic Laboratory: An Enantioselective Aldol Reaction Catalyzed by Methyl Prolinamide

    Science.gov (United States)

    Wade, Edmir O.; Walsh, Kenneth E.

    2011-01-01

    In recent years, there has been an explosion of research concerning the area of organocatalysis. A multistep capstone laboratory project that combines traditional reactions frequently found in organic laboratory curriculums with this new field of research is described. In this experiment, the students synthesize a prolinamide-based organocatalyst…

  14. Preparation and Catalytic Oxidation Activity on 2-mercaptoethanol of a Novel Catalytic Cellulose Fibres

    Institute of Scientific and Technical Information of China (English)

    YAO Yu-yuan; LI Ying-jie; CHEN Wen-xing; Lü Wang-yang; Lü Su-fang; XU Min-hong; LIU Fan

    2007-01-01

    Cobalt tetra(N-carbonylacylic) aminophthalocyanine was supported on cellulose fibres by graft reaction to obtain a novel polymer catalyst, catalytic cellulose fibres (CCF),and the optimal supporting conditions were pH = 6, 80℃,t = 120 min. The catalytic oxidation activity of CCF towards oxidation of 2-mereaptoethanol (MEA) in aqueous solution was investigated. The experimental results demonstrated that CCF had good catalytic oxidation activity on MEA at room temperature, causing no secondary pollution and remaining efficient for the repetitive tests with no obvious decrease of catalytic activity.

  15. Catalytic reaction on FeN4/C site of nitrogen functionalized carbon nanotubes as cathode catalyst for hydrogen fuel cells

    Energy Technology Data Exchange (ETDEWEB)

    Gao, Feng [Southern Univ., Baton Rouge, LA (United States); A& M College, Baton Rouge, LA (United States); Zhao, Guang-Lin [Southern Univ., Baton Rouge, LA (United States); A& M College, Baton Rouge, LA (United States); Wang, Zhou [Southern Univ., Baton Rouge, LA (United States); A& M College, Baton Rouge, LA (United States); Bagayoko, Diola [Southern Univ., Baton Rouge, LA (United States); Liu, Di-Jia [Argonne National Lab. (ANL), Argonne, IL (United States)

    2015-01-21

    First, we utilized first-principles spin-polarized density functional theory (DFT) calculations to study the electrocatalytic reaction steps on FeN4/C site of carbon nanotubes. O2 molecule can be adsorbed and partially reduced on FeN4/C site without any activation energy barrier. The partially reduced O2 further reacts with H+ and e- through a direct pathway (DPW) and form two water molecules without any activation energy barrier. Through an indirect pathway (IDPW), there is an activation energy barrier of ~ 0.15 eV for the formation of the first H2O molecule. Finally, the formation of the second H2O molecule through IDPW does not have any activation energy barrier.

  16. Synthesis and catalytic properties on oxidation reaction of goethite containing niobium; Sintese e propriedades cataliticas em reacoes de oxidacao de goethitas contendo niobio

    Energy Technology Data Exchange (ETDEWEB)

    Oliveira, Luiz C.A.; Goncalves, Maraisa; Oliveira, Diana Q.L.; Guarieiro, Aline L.N. [Universidade Federal de Lavras, MG (Brazil). Dept. de Quimica]. E-mail: luizoliveira@ufla.br; Pereira, Marcio C. [Universidade Federal de Minas Gerais (UFMG), Belo Horizonte, MG (Brazil). Dept. de Quimica

    2007-07-15

    Nb-substituted goethites have been prepared and characterized by Moessbauer spectroscopy, XRD, SEM and BET surface area measurements. Moessbauer and XRD analyses suggested that Nb replaces Fe{sup 3+} in the structure with duplet formation. The insertion of Nb into the goethite structure caused a significant increase in the BET surface area of the material. The prepared {alpha}-Fe{sub 1-x}Nb{sub x}OOH was investigated for the H{sub 2}O{sub 2} decomposition to O{sub 2} and for the Fenton reaction to oxidize the dye methylene blue. It was observed that the introduction of Nb in to goethite produced a strong increase in the activity of oxidation of the dye contaminant by H{sub 2}O{sub 2}. (author)

  17. Au+Au reactions at the AGS: Experiments E866 and E917

    Energy Technology Data Exchange (ETDEWEB)

    Ogilvie, C.A.; Ahle, L. [Massachusetts Inst. of Tech., Cambridge, MA (United States). Dept. of Physics; Akiba, Y. [KEK, Tanashi (Japan)] [and others; E866 Collaboration; E917 Collaboration

    1997-12-01

    Particle production and correlation functions from Au+Au reactions have been measured as a function of both beam energy (2--10.7 AGeV) and impact parameter. These results are used to probe the dynamics of heavy-ion reactions, confront hadronic models over a wide range of conditions and to search for the onset of new phenomena.

  18. A Clinico-Pathological Study of Lichenoid Tissue Reactions-A Tertiary Care experience

    OpenAIRE

    Kumar U, Mahesh; Yelikar, Balasaheb Ramling; Inamadar, Arun C.; Umesh, Swaroopa; Singhal, Amrita; Anirudha V Kushtagi

    2012-01-01

    Introduction: The aim of this article was to study the spectrum of clinico-histopathological lesions with an age and sex distribution in various lichenoid reactions of the skin. The spectrum of clinical diseases which is related to the lichenoid tissue reaction is wider. There is a recent increase in the relatively new subgroups of the lichenoid clinical picture.

  19. Performance of Catalyst Ni-NiO/γ-Al2O3 in the Catalytic Reaction from Tetrahydrofurfuryl to Pyridine%Ni-NiO/γ-Al2O3催化四氢糠醇制备吡啶

    Institute of Scientific and Technical Information of China (English)

    徐哲; 张卫红; 孟舒献; 冯亚青

    2012-01-01

    采用捏合挤条法制备了催化剂Ni-NiO/γ-Al2 O3,用SEM、XRD、BET等方法对催化剂进行了表征,并将催化剂应用于四氢糠醇(THFA)与氨气在固定床反应器中制备吡啶.考察了Ni-NiO负载量、温度、氨醇摩尔比等因素对催化反应的影响,结果表明,随着催化剂组分Ni-NiO负载量的升高,吡啶的收率随之升高,而哌啶的收率随之降低,异喹啉收率在Ni -NiO质量分数为20%时达最高;在350~550℃,随着温度的升高,吡啶的收率随之升高,而副产物哌啶的收率随之降低,异喹啉在400℃收率较高;当氨醇摩尔比为3∶1时,吡啶与异喹啉的收率较高,2∶1时哌啶收率较高.%The catalyst Ni-NiO/γ-Al2O3 was prepared by kneading extruding method, and was characterized by means of SEM,XRD,BET and some other methods. It was then applied in the catalytic reaction from tetrahydrofurfuryl and ammonia to pyridine in a fixed-bed reactor. The influence of such factors as catalyst content,temperature,molar ratio of ammonia to THFA on the catalytic reaction was investigated. The experimental results are as follows. With the increase of Ni-NiO content in the catalyst,the yield of pyridine increases,while that of piperidine decreases. The yield of isoquinoline is of a higher value at the Ni-NiO content of 20%. Within a certain temperature range between 350 -550 ℃ ,with the temperature increasing, the yield of pyridine increases, while that of piperidine decreases. The yield of isoquinoline is the highest at the temperature of 400 ℃. When the molar ratio of ammonia to THFA was 3:1, the yield of pyridine and that of isoquinoline are both relatively higher. When that ratio was 2:l ,the yield of piperidine is relatively higher.

  20. Proton-gamma coincidence experiment on medium mass nuclei at 400MeV and study of reaction mechanisms

    International Nuclear Information System (INIS)

    Previous γ ray production experiments produced by proton on nuclei show important cross sections for residual nuclei corresponding to a four nucleon (2p + 2n) removal. With our (p - γ) coincidence experiment the forward emitted proton reflects the primary interaction and the γ spectra characterizes the final state of the reaction. Protons are detected with a magnetic spectrometer and γ rays are selected with a Ge(Li) diode. Angular and momentum analysis of scattered protons demonstrate a primary quasi free process on nucleons. No indication of knock out reactions on clusters has been seen. The residual nuclei are mainly produced by evaporation processes. A theoretical calculation involving intranuclear cascades and evaporation processes has been performed. The nucleus model is based upon a Fermi gas and nuclear density agrees with diffusion electron experiments. Residual nuclei far from target are well described with a such model. Residual nuclei near the target are sensitive to the nuclear structure

  1. DNA-binding, catalytic oxidation, C—C coupling reactions and antibacterial activities of binuclear Ru(II thiosemicarbazone complexes: Synthesis and spectral characterization

    Directory of Open Access Journals (Sweden)

    Arumugam Manimaran

    2012-07-01

    Full Text Available New hexa-coordinated binuclear Ru(II thiosemicarbazone complexes of the type {[(B(EPh3(COClRu]2L} (where, E = P or As; B = PPh3 or AsPh3 or pyridine; L = mononucleating NS donor of N-substituted thiosemicarbazones have been synthesized and characterized by elemental analysis, FT-IR, UV–vis and 31P{1H} NMR cyclic voltammetric studies. The DNA-binding studies of Ru(II complexes with calf thymus DNA (CT-DNA were investigated by UV–vis, viscosity measurements, gel-electrophoresis and fluorescence spectroscopy. The new complexes have been used as catalysts in C—C coupling reaction and in the oxidation of alcohols to their corresponding carbonyl compounds by using NMO as co-oxidant and molecular oxygen (O2 atmosphere at ambient temperature. Further, the new binucleating thiosemicarbazone ligands and their Ru(II complexes were also screened for their antibacterial activity against Klebsiella pneumoniae, Shigella sp., Micrococcus luteus, Escherichia coli and Salmonella typhi. From this study, it was found out that the activity of the complexes almost reaches the effectiveness of the conventional bacteriocide.

  2. Silver nanocluster catalytic microreactors for water purification

    Science.gov (United States)

    Da Silva, B.; Habibi, M.; Ognier, S.; Schelcher, G.; Mostafavi-Amjad, J.; Khalesifard, H. R. M.; Tatoulian, M.; Bonn, D.

    2016-07-01

    A new method for the elaboration of a novel type of catalytic microsystem with a high specific area catalyst is developed. A silver nanocluster catalytic microreactor was elaborated by doping a soda-lime glass with a silver salt. By applying a high power laser beam to the glass, silver nanoclusters are obtained at one of the surfaces which were characterized by BET measurements and AFM. A microfluidic chip was obtained by sealing the silver coated glass with a NOA 81 microchannel. The catalytic activity of the silver nanoclusters was then tested for the efficiency of water purification by using catalytic ozonation to oxidize an organic pollutant. The silver nanoclusters were found to be very stable in the microreactor and efficiently oxidized the pollutant, in spite of the very short residence times in the microchannel. This opens the way to study catalytic reactions in microchannels without the need of introducing the catalyst as a powder or manufacturing complex packed bed microreactors.

  3. Employee Reactions to an Open-Plan Office: A Naturally Occurring Quasi-Experiment.

    Science.gov (United States)

    Oldham, Greg R.; Brass, Daniel J.

    1979-01-01

    Examines changes in reactions of employees to work after they moved from a conventional office to an open-plan office. Employee satisfaction and internal motivation decreased significantly after the move to the open office. (Author/IRT)

  4. Dynamics of ion–molecule reactions from beam experiments: A historical survey

    Czech Academy of Sciences Publication Activity Database

    Herman, Zdeněk; Futrell, J. H.

    2015-01-01

    Roč. 377, FEB 2015 (2015), s. 84-92. ISSN 1387-3806 Institutional support: RVO:61388955 Keywords : Ion–molecule reactions * Dynamics * Beam scattering Subject RIV: CF - Physical ; Theoretical Chemistry Impact factor: 1.972, year: 2014

  5. Event reconstruction in experiments with separation of reaction channels by missing mass method on Hyperon facility

    International Nuclear Information System (INIS)

    The methods of trajectory reconstruction and determination of kinematic parameters of charged particles used when studying hypercharged reactions π+p → K+Σ+, Σ+(1385) and π+n → K+Λ, Σ0 with the help of ''Hyperon'' facility are described. The main stages of event treatment are presented. The application of these methods has provided a necessary resolution for separation of the channels of the mentioned reactions by the missing mass method

  6. The Stock Market Reactions to DomesticJoint Venture Announcements:The Malaysian Experience

    OpenAIRE

    Abdul Aziz, Azah Najwa

    2005-01-01

    This study examines the stock market’s reactions to domestic joint venture announcements. It focuses on the Malaysian market and economy, and how corporate members, i.e. firm managers and investors perceive the announcements of joint venture formations. 75 Malaysian public listed companies that involved in 35 joint ventures are selected and examined. A few alternative hypotheses concerning the stock market’s reactions to domestic joint venture announcements are tested. The Wealth Effect Hypot...

  7. Radical-ion-pair reactions are the biochemical equivalent of the optical double slit experiment

    OpenAIRE

    Kominis, I. K.

    2010-01-01

    Radical-ion-pair reactions were recently shown to represent a rich biophysical laboratory for the application of quantum measurement theory methods and concepts. We here show that radical-ion-pair reactions essentially form a non-linear biochemical double slit interferometer. Quantum coherence effects are visible when "which-path" information is limited, and the incoherent limit is approached when measurement-induced decoherence sets in. Based on this analogy with the optical double slit expe...

  8. Adverse Reactions in Allogeneic Blood Donors: A Tertiary Care Experience from a Developing Country

    OpenAIRE

    Sadia Sultan; Mohammad Amjad Baig; Syed Mohammed Irfan; Syed Ijlal Ahmed; Syeda Faiza Hasan

    2016-01-01

    Objectives: Fragmented blood transfusion services along with an unmotivated blood donation culture often leads to blood shortage. Donor retention is crucial to meet the increasing blood demand, and adverse donor reactions have a negative impact on donor return. The aim of this study was to estimate adverse donor reactions and identify any demographic association.   Methods: We conducted a prospective study between January 2011 and December 2013. A total of 41,759 healthy donors were enrol...

  9. Rapid and facile preparation of zinc ferrite (ZnFe{sub 2}O{sub 4}) oxide by microwave-solvothermal technique and its catalytic activity in heterogeneous photo-Fenton reaction

    Energy Technology Data Exchange (ETDEWEB)

    Anchieta, Chayene G.; Severo, Eric C.; Rigo, Caroline; Mazutti, Marcio A. [Department of Chemical Engineering, Federal University of Santa Maria, 97105-900, Santa Maria (Brazil); Kuhn, Raquel C., E-mail: raquelckuhn@yahoo.com.br [Department of Chemical Engineering, Federal University of Santa Maria, 97105-900, Santa Maria (Brazil); Muller, Edson I.; Flores, Erico M.M. [Department of Chemistry, Federal University of Santa Maria, 97105-900, Santa Maria (Brazil); Moreira, Regina F.P.M. [Department of Chemical Engineering and Food Engineering, Federal University of Santa Catarina, 88040-970, Florianópolis (Brazil); Foletto, Edson L. [Department of Chemical Engineering, Federal University of Santa Maria, 97105-900, Santa Maria (Brazil)

    2015-06-15

    In this work zinc ferrite (ZnFe{sub 2}O{sub 4}) oxide was rapidly and easily prepared by microwave-solvothermal route and its catalytic property in photo-Fenton reaction was evaluated. The effects of microwave heating time and power on the properties of produced particles were investigated. X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), atomic force microscopy (AFM) and nitrogen adsorption–desorption isotherms were the techniques used for characterizing the solid products. The synthesized material was tested as a catalyst in the degradation of the textile dye molecule by the heterogeneous photo-Fenton process. Characterization results showed that the microwave heating time and power have significant influences on the formation of the phase spinel as well as on its physical properties. The reaction results showed that the ZnFe{sub 2}O{sub 4} oxide has good photocatalytic activity, which can be attributed to high surface area and pore volume, and large pore size. The ZnFe{sub 2}O{sub 4} oxide produced by the microwave irradiation exhibited promising photocatalytic activity for the removal of textile dye, reaching nearly 100% of decolorization at 40 min and 60% of mineralization at 240 min. Therefore, ZnFe{sub 2}O{sub 4} particles rapidly prepared by the microwave route have the potential for use in treatment of textile wastewater by the heterogeneous photo-Fenton process. - Highlights: • ZnFe{sub 2}O{sub 4} was synthesized by microwave-solvothermal method. • ZnFe{sub 2}O{sub 4} was prepared by different microwave heating times and powers. • ZnFe{sub 2}O{sub 4} was used as heterogeneous photo-Fenton catalyst. • Degradation of Procion red dye using heterogeneous photo-Fenton process. • ZnFe{sub 2}O{sub 4} was highly efficient to degrade textile dye under visible light.

  10. Rapid and facile preparation of zinc ferrite (ZnFe2O4) oxide by microwave-solvothermal technique and its catalytic activity in heterogeneous photo-Fenton reaction

    International Nuclear Information System (INIS)

    In this work zinc ferrite (ZnFe2O4) oxide was rapidly and easily prepared by microwave-solvothermal route and its catalytic property in photo-Fenton reaction was evaluated. The effects of microwave heating time and power on the properties of produced particles were investigated. X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), atomic force microscopy (AFM) and nitrogen adsorption–desorption isotherms were the techniques used for characterizing the solid products. The synthesized material was tested as a catalyst in the degradation of the textile dye molecule by the heterogeneous photo-Fenton process. Characterization results showed that the microwave heating time and power have significant influences on the formation of the phase spinel as well as on its physical properties. The reaction results showed that the ZnFe2O4 oxide has good photocatalytic activity, which can be attributed to high surface area and pore volume, and large pore size. The ZnFe2O4 oxide produced by the microwave irradiation exhibited promising photocatalytic activity for the removal of textile dye, reaching nearly 100% of decolorization at 40 min and 60% of mineralization at 240 min. Therefore, ZnFe2O4 particles rapidly prepared by the microwave route have the potential for use in treatment of textile wastewater by the heterogeneous photo-Fenton process. - Highlights: • ZnFe2O4 was synthesized by microwave-solvothermal method. • ZnFe2O4 was prepared by different microwave heating times and powers. • ZnFe2O4 was used as heterogeneous photo-Fenton catalyst. • Degradation of Procion red dye using heterogeneous photo-Fenton process. • ZnFe2O4 was highly efficient to degrade textile dye under visible light

  11. SYNTHESIS, CHARACTERIZATION AND CATALYTIC PERFORMANCE OF Cu-CONTAINING SBA-15 CATALYSTS FOR DeNPAC REACTION%含Cu SBA-15催化剂的合成、表征及DeNPAC反应性能评价

    Institute of Scientific and Technical Information of China (English)

    曾厚旭; YU L E; KAWI S

    2008-01-01

    CuO/SBA-15, CuAI/SBA-15 and CuOAI/SBA-15 were synthesized by wet-impregnation and ion-exchange methods. The acidic properties of SBA-15 were improved by incorporating AI with post-synthesis method. The Cu was introduced to SBA-15 and AI/SBA-15 supports by wet-impregnation and ion-exchange method, respectively. CuAI/SBA-15 showed the best catalytic performance by giving the highest conversion of pyridine with the lowest yield of NOx in the reaction of decomposing nitrogen-containing polycyclic aromatic compounds (DeNPAC). The enhanced reaction activity of CuAl/SBA-15 for DeNPAC could be attributed to the hi-functionality of acid and metallic ion of CuAl/SBA-15.%采用浸渍法和离子交换法合成了CuO/SBA-15、CuAl/SBA-15和CuOAl/SBA-15 3种催化剂.SBA-15的酸功能通过负载A1而得以改进.通过浸渍法和离子交换法将Cu引入SBA-15和A1/SBA-15中.3种催化剂相比,CuAl/sBA-15在DeNPAC反应中具有最高的吡啶转化率的同时,具有最低的NOx产率.CuAI/SBA-15具有较好的含氮多环芳烃化合物脱除反应性能的原因,可能是其酸功能和金属离子功能共同作用的结果.

  12. 新型三元催化器特性的试验研究与数值仿真%Experiment and Numerical Simulation on the Characteristics of the New Type of Three Way Catalytic Device

    Institute of Scientific and Technical Information of China (English)

    韩建军; 蒋彦龙; 王合旭; 熊文倩

    2015-01-01

    Three way catalytic converter is the necessary part of automobile.It will make the exhaust emitted by the cars become harmless,and it greatly reduces exhaust pollution.Based on the flow resistance study of the traditional straight-through type of three catalytic converter,the method that combined with FLUENT numerical simulation is proposed,and we study the flow resist-ance of a new type of three way catalytic converter structure using metal carrier (bypass type of three way catalytic converter).Fi-nally,it is verified by the pressure lose experiment that after the comparative analysis with the traditional straight-through type of three way catalytic converter,we can get some conclusion:under the same inlet air flow and exhaust pressure,the pressure drop (flow resistance)of the new type three way catalytic converter is smaller than the straight-through type three way catalytic convert-er′s.In addition,the airflow uniformity of the new type of three way catalytic converter is much better.In general,the new type of three way catalyticair flow characteristics is better than traditional type of three way catalytic converter,and its airflow uniformity is better and pressure lose is smaller,so it is conducive to improve the catalytic efficiency and prolong the service life.%三元催化器是汽车必不可少的设备之一,它将汽车排放的尾气转变为无毒无害的气体,大大减少了尾气对大气的污染。在研究传统直通型三元催化器流阻的基础上,基于 FLUENT 仿真模拟对一种采用金属载体的新型三元催化器结构(旁通型三元催化器)流阻进行研究,最后结合压力损失试验进行验证,并和传统直通型三元催化器对比分析后,得出如下结论:在相同进气流量及排气压力下,新型催化器的整体压降(流阻)要小于直通型三元催化器,同时新型三元催化器载体中的气流均匀性好于直通型三元催化器,表明新型三元催化器的气流

  13. Temperature Modulation of a Catalytic Gas Sensor

    OpenAIRE

    Eike Brauns; Eva Morsbach; Sebastian Kunz; Marcus Baeumer; Walter Lang

    2014-01-01

    The use of catalytic gas sensors usually offers low selectivity, only based on their different sensitivities for various gases due to their different heats of reaction. Furthermore, the identification of the gas present is not possible, which leads to possible misinterpretation of the sensor signals. The use of micro-machined catalytic gas sensors offers great advantages regarding the response time, which allows advanced analysis of the sensor response. By using temperature modulation, additi...

  14. Catalytic ammonia oxidation to nitrogen (I) oxide

    OpenAIRE

    MASALITINA NATALIYA YUREVNA; SAVENKOV ANATOLIY SERGEEVICH

    2015-01-01

    The process of synthesis of nitrous oxide by low-temperature catalytical oxidation of NH has been investigated for organic synthesis. The investigation has been carried out by the stage separation approach with NH oxidation occurring in several reaction zones, which characterized by different catalytic conditions. The selectivity for N₂O was 92–92,5 % at the ammonia conversion of 98–99.5 % in the optimal temperature range.

  15. Determination of transport and reaction swarm coefficients from the analysis of complex transient pulses from the pulsed Townsend experiment

    International Nuclear Information System (INIS)

    We present in this paper the interpretation and analysis of transient pulses from a pulsed Townsend experiment by solving the continuity equations of the charged carriers (electrons and ions) involved in the avalanche. The set of second order partial differential equations is solved by SIMAV, a simulator designed specifically for the pulsed Townsend avalanche. Complex situations involving processes such as electron detachment, ion-molecule reactions, Penning ionization and secondary electron emission from ion impact at the cathode, virtually impossible to solve analytically, are discussed here to illustrate the capability of the simulator to help explain the various reaction processes involved in the avalanche, and also to derive some of the transport and reaction coefficients.

  16. Determination of transport and reaction swarm coefficients from the analysis of complex transient pulses from the pulsed Townsend experiment

    Science.gov (United States)

    Bekstein, A.; de Urquijo, J.; Ducasse, O.; Rodríguez-Luna, J. C.; Juárez, A. M.

    2012-06-01

    We present in this paper the interpretation and analysis of transient pulses from a pulsed Townsend experiment by solving the continuity equations of the charged carriers (electrons and ions) involved in the avalanche. The set of second order partial differential equations is solved by SIMAV, a simulator designed specifically for the pulsed Townsend avalanche. Complex situations involving processes such as electron detachment, ion-molecule reactions, Penning ionization and secondary electron emission from ion impact at the cathode, virtually impossible to solve analytically, are discussed here to illustrate the capability of the simulator to help explain the various reaction processes involved in the avalanche, and also to derive some of the transport and reaction coefficients.

  17. A test experiment for the study of excited states in Z≅56, N≅80 nuclei via deep inelastic reactions

    International Nuclear Information System (INIS)

    To check the feasibility of deep inelastic heavy-ion reactions in populating the high-spin states in Z ≅56, N ≅ 80 nuclei, a test experiment has been carried out by using the reaction of 410 MeV 82Se + na'tBa. γ-γ coincidence measurements have been performed using in-beam γ spectroscopy techniques. Population cross-section of excited states in both target-like fragments and projectile-like fragments have been estimated. New γ transitions were identified in several target-like fragments. A new level scheme including five new levels has been established for 136Ba. The preliminary results show that deep inelastic heavy-ion reactions are very promising for populating the excited states in the Z ≅ 56, N ≅ 80 region

  18. Catalytic Spectrophotometric Determination of Chromium

    OpenAIRE

    STOYANOVA, Angelina Miltcheva

    2005-01-01

    The catalytic effect of chromium(III) and chromium(VI) on the oxidation of sulfanilic acid by hydrogen peroxide was studied. The reaction was followed spectrophotometrically by measuring the absorbance of the reaction product at 360 nm. Under the optimum conditions 2 calibration graphs (for chromium(III) up to 100 ng mL-1, and for chromium(VI) up to 200 ng mL-1) were obtained, using the ``fixed time'' method with detection limits of 4.9 ng mL-1 and 3.8 ng mL-1, respectively...

  19. Adverse Reactions in Allogeneic Blood Donors: A Tertiary Care Experience from a Developing Country

    Science.gov (United States)

    Sultan, Sadia; Baig, Mohammad Amjad; Irfan, Syed Mohammed; Ahmed, Syed Ijlal; Hasan, Syeda Faiza

    2016-01-01

    Objectives Fragmented blood transfusion services along with an unmotivated blood donation culture often leads to blood shortage. Donor retention is crucial to meet the increasing blood demand, and adverse donor reactions have a negative impact on donor return. The aim of this study was to estimate adverse donor reactions and identify any demographic association.   Methods We conducted a prospective study between January 2011 and December 2013. A total of 41,759 healthy donors were enrolled. Professionally trained donor attendants drew blood and all donors were observed during and following donation for possible adverse events for 20 minutes. Blood donors were asked to report if they suffered from any delayed adverse consequences.   Results Out of 41,759 blood donors, 537 (1.3%) experienced adverse reactions. The incidence was one in every 78 donations. The mean age of donors who experienced adverse events was 26.0±6.8 years, and all were male. Out of 537 donors, 429 (80%) developed vasovagal reaction (VVR), 133 (25%) had nausea, 63 (12%) fainted, 35 (6%) developed hyperventilation, 9 (2%) had delayed syncope, and 9 (2%) developed hematoma. Arterial prick, nerve injury, cardiac arrest, and seizures were not observed. Donors aged less than importance of these parameters in the donation process. A well-trained and experienced phlebotomist and pre-evaluation counseling of blood donors could further minimize the adverse reactions.

  20. Diagnostic technique for measuring fusion reaction rate for inertial confinement fusion experiments at Shen Guang-III prototype laser facility

    International Nuclear Information System (INIS)

    A study is conducted using a two-dimensional simulation program (Lared-s) with the goal of developing a technique to evaluate the effect of Rayleigh-Taylor growth in a neutron fusion reaction region. Two peaks of fusion reaction rate are simulated by using a two-dimensional simulation program (Lared-s) and confirmed by the experimental results. A neutron temporal diagnostic (NTD) system is developed with a high temporal resolution of ∼ 30 ps at the Shen Guang-III (SG-III) prototype laser facility in China, to measure the fusion reaction rate history. With the shape of neutron reaction rate curve and the spherical harmonic function in this paper, the degree of Rayleigh-Taylor growth and the main source of the neutron yield in our experiment can be estimated qualitatively. This technique, including the diagnostic system and the simulation program, may provide important information for obtaining a higher neutron yield in implosion experiments of inertial confinement fusion

  1. The Monte Carlo simulation of the reaction π-p → K0 Λ in the PT55 experiment

    International Nuclear Information System (INIS)

    A Monte Carlo simulation is described of an experiment in which the polarization and spin-rotation parameters for the reaction πp → K0 Λ off a polarized target was studied (the PT 55 experiment). Having examined the purpose of the simulation, the main techniques used in simulating the kinematics of the reaction are considered and the simulation of the apparatus is described. In discussing the more general aspects of the Monte Carlo program, the generation of pseudo-random numbers with suitable distribution functions is examined and some of the uses to which the program has already been put are given. There are three appendices giving the more technical details of kinematic transformations, the simulation of beam track measurement errors and the Gaussian distribution generator. (U.K.)

  2. Catalytic properties of CuO/Sn0.9Ti0.1O2 and CuO/Sn0.7Ti0.3O2 in NO+CO reaction

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    Using SnxTi1-xO2 as carriers, CuO/Sn0.9Ti0.1O2 and CuO/Sn0.7Ti0.3O2 catalysts with different loading amounts of copper oxide (CuO) were prepared by an impregnation method. The catalytic properties of CuO/Sn0.9Ti0.1O2 and CuO/Sn0.7Ti0.3O2 were examined using a microreactor-gas chromatography (GC) NO+CO reaction system and the methods of BET (Brunauer-Emmett-Teller), TG-DTA (themogravimetric and differential thermal analysis), X-ray diffraction (XRD) and H2-temperature programmed reduction (TPR). The results showed that NO conversions of Sn0.9Ti0.1O2 and Sn0.7Ti0.3O2 were 47.2% and 43.6%respectively, which increased to 95.3% and 90.9% at 6 wt% CuO loading. However, further increase in CuO loading caused a decrease in the catalytic activity. The nitrogen adsorption-desorption isotherm and pore-size distribution curve of Sn0.9Ti0.1O2 and Sn0.7Ti0.3O2 represented type Ⅳ of the BDDT (Brunauer, Deming, Deming and Teller) system and a typical mesoporous sample.There were two CuO diffraction peaks (2θ 35.5° and 38.7°), and the diffraction peak areas increased with increasing CuO loading.TPR analysis also detected three peaks (α, β and γ) from the CuO-loaded catalysts, suggesting that the α peak was the reduction of the highly dispersed copper oxide, the β peak was the reduction of the isolated copper oxide, and the γ peak was the reduction of crystal phase copper oxide. In addition, a fourth peak (δ) of the catalysts meant that the SnxTi1-xO2 mixed oxides could be reductive.

  3. Ignition and Growth Modeling of Detonation Reaction Zone Experiments on Single Crystals of PETN and HMX

    Science.gov (United States)

    White, Bradley; Tarver, Craig

    2015-06-01

    Fedorov et al. reported nanosecond time resolved interface particle velocity records for detonation reaction zone profiles of single crystals of PETN and HMX with adjoining LiF windows. Von Neumann spike and Chapman-Jouguet pressures were measured, and reaction zone lengths and times wereinferred. The single crystal detonation velocities and von Neumann spike pressures are higher than those measured for heterogeneous PETN and HMX-based explosives pressed to 98-99% theoretical maximum density. Due to the absence of voids, the single crystal detonation reaction zone lengths and times for both PETN and HMX were longer than those for their heterogeneous explosives. Ignition and Growth modeling results are compared to the single crystal PETN and HMX measurements and to previous experimental results for pressed PETN and HMX charges. This work was performed under the auspices of the U. S. Department of Energy by the Lawrence Livermore National Laboratory under Contract No. DE-AC52-07NA27344.

  4. Adverse Reactions in Allogeneic Blood Donors: A Tertiary Care Experience from a Developing Country

    Directory of Open Access Journals (Sweden)

    Sadia Sultan

    2016-03-01

    Full Text Available Objectives: Fragmented blood transfusion services along with an unmotivated blood donation culture often leads to blood shortage. Donor retention is crucial to meet the increasing blood demand, and adverse donor reactions have a negative impact on donor return. The aim of this study was to estimate adverse donor reactions and identify any demographic association.   Methods: We conducted a prospective study between January 2011 and December 2013. A total of 41,759 healthy donors were enrolled. Professionally trained donor attendants drew blood and all donors were observed during and following donation for possible adverse events for 20 minutes. Blood donors were asked to report if they suffered from any delayed adverse consequences.   Results: Out of 41,759 blood donors, 537 (1.3% experienced adverse reactions. The incidence was one in every 78 donations. The mean age of donors who experienced adverse events was 26.0±6.8 years, and all were male. Out of 537 donors, 429 (80% developed vasovagal reaction (VVR, 133 (25% had nausea, 63 (12% fainted, 35 (6% developed hyperventilation, 9 (2% had delayed syncope, and 9 (2% developed hematoma. Arterial prick, nerve injury, cardiac arrest, and seizures were not observed. Donors aged less than < 30 years and weighing < 70 kg were significantly associated with VVR, hyperventilation, and nausea (p < 0.005. Undergraduates and Urdu speaking donors also had a significant association with fainting and nausea, respectively (p < 0.05.   Conclusion: The prevalence of adverse events was low at our tertiary center. A VVR was the predominant adverse reaction and was associated with age and weight. Our study highlights the importance of these parameters in the donation process. A well-trained and experienced phlebotomist and pre-evaluation counseling of blood donors could further minimize the adverse reactions.

  5. Structural and spectroscopic study of reactions between chelating zinc-binding groups and mimics of the matrix metalloproteinase and disintegrin metalloprotease catalytic sites: the coordination chemistry of metalloprotease inhibition.

    Science.gov (United States)

    He, Hongshan; Puerta, David T; Cohen, Seth M; Rodgers, Kenton R

    2005-10-17

    To understand the coordination chemistry of zinc-binding groups (ZBGs) with catalytic zinc centers in matrix metalloproteinases (MMPs) and disintegrin metalloproteases (ADAMs), we have undertaken a model compound study centered around tris(3,5-methylphenypyrazolyl)hydroboratozinc(II) hydroxide and aqua complexes ([Tp(Ph,Me)ZnOH] and [Tp(Ph,Me)Zn(OH2)]+, respectively, wherein (Tp(Ph,Me))- = hydrotris(3,5-methylphenylpyrazolyl)borate) and the products of their reactions with a class of chelating Schiff's base ligands. The results show that the protic ligands, HL (HL = N-propyl-1-(5-methyl-2-imidazolyl)methanimine (5-Me-4-ImHPr), N-propyl-1-(4-imidazolyl)methanimine (4-ImHPr), and N-propyl-1-(2-imidazolyl)methanimine (2-ImHPr)), react with [Tp(Ph,Me)ZnOH] and give products with the general formula [Tp(Ph,Me)ZnL], whereas reactions with neutral aprotic ligands, L' (L' = N-propyl-1-(1-methyl-2-imidazolyl)methanimine (1-Me-2-ImPr) and N-propyl-1-(2-thiazolyl)methanimine (2-TaPr)), yield the corresponding [Tp(Ph,Me)ZnL]+ complexes. Although the phenol group of N-propyl-1-(2-hydroxyphenyl)methanimine (2-HOPhPr) is protic, this ligand forms a cationic four-coordinate complex containing an intraligand hydrogen bond. The solid-state structures of these complexes were determined by single-crystal X-ray diffraction, and the results showed that the protic ligands form five-membered chelates of the Zn2+ ion. All ligands displace the aqua ligand in [Tp(Ph,Me)Zn(OH2)]+ to yield complexes having 1H NMR spectra consistent with the formation of five membered chelates. The 1H resonance frequencies of the chelating ligands typically shift upfield upon coordination to the zinc center, due to ring current effects from the pendant phenyl groups of the (Tp(Ph,Me))- ligand. Thus, the 1H NMR spectra provide a convenient and sensitive means of tracking the solution reactions by titration. The resulting series of spectra showed that the stabilities of the chelates in solution depend on the

  6. Two Experiments to Approach the Boltzmann Factor: Chemical Reaction and Viscous Flow

    Science.gov (United States)

    Fazio, Claudio; Battaglia, Onofrio R.; Guastella, Ivan

    2012-01-01

    In this paper we discuss a pedagogical approach aimed at pointing out the role played by the Boltzmann factor in describing phenomena usually perceived as regulated by different mechanisms of functioning. Experimental results regarding some aspects of a chemical reaction and of the viscous flow of some liquids are analysed and described in terms…

  7. Dynamics of chemical reactions of multiply-charged cations: Information from beam scattering experiments

    Czech Academy of Sciences Publication Activity Database

    Herman, Zdeněk

    2015-01-01

    Roč. 378, FEB 2015 (2015), s. 113-126. ISSN 1387-3806 Institutional support: RVO:61388955 Keywords : Multiply-charged ions * Dynamics of chemical reactions * Beam scattering Subject RIV: CF - Physical ; Theoretical Chemistry Impact factor: 1.972, year: 2014

  8. Catalytic and non-catalytic wet air oxidation of sodium dodecylbenzene sulfonate: kinetics and biodegradability enhancement.

    Science.gov (United States)

    Suárez-Ojeda, María Eugenia; Kim, Jungkwon; Carrera, Julián; Metcalfe, Ian S; Font, Josep

    2007-06-18

    Wet air oxidation (WAO) and catalytic wet air oxidation (CWAO) were investigated as suitable precursors for the biological treatment of industrial wastewater containing sodium dodecylbenzene sulfonate (DBS). Two hours WAO semi-batch experiments were conducted at 15 bar of oxygen partial pressure (P(O2)) and at 180, 200 and 220 degrees C. It was found that the highest temperature provides appreciable total organic carbon (TOC) and chemical oxygen demand (COD) abatement of about 42 and 47%, correspondingly. Based on the main identified intermediates (acetic acid and sulfobenzoic acid) a reaction pathway for DBS and a kinetic model in WAO were proposed. In the case of CWAO experiments, seventy-two hours tests were done in a fixed bed reactor in continuous trickle flow regime, using a commercial activated carbon (AC) as catalyst. The temperature and P(O2) were 140-160 degrees C and 2-9 bar, respectively. The influence of the operating conditions on the DBS oxidation, the occurrence of oxidative coupling reactions over the AC, and the catalytic activity (in terms of substrate removal) were established. The results show that the AC without any supported active metal behaves bi-functional as adsorbent and catalyst, giving TOC conversions up to 52% at 160 degrees C and 2 bar of P(O2), which were comparable to those obtained in WAO experiments. Respirometric tests were completed before and after CWAO and to the main intermediates identified through the WAO and CWAO oxidation route. Then, the readily biodegradable COD (COD(RB)) of the CWAO and WAO effluents were found. Taking into account these results it was possible to compare whether or not the CWAO or WAO effluents were suitable for a conventional activated sludge plant inoculated with non adapted culture. PMID:17363148

  9. Catalytic and non-catalytic wet air oxidation of sodium dodecylbenzene sulfonate: Kinetics and biodegradability enhancement

    International Nuclear Information System (INIS)

    Wet air oxidation (WAO) and catalytic wet air oxidation (CWAO) were investigated as suitable precursors for the biological treatment of industrial wastewater containing sodium dodecylbenzene sulfonate (DBS). Two hours WAO semi-batch experiments were conducted at 15bar of oxygen partial pressure (PO2) and at 180, 200 and 220deg. C. It was found that the highest temperature provides appreciable total organic carbon (TOC) and chemical oxygen demand (COD) abatement of about 42 and 47%, correspondingly. Based on the main identified intermediates (acetic acid and sulfobenzoic acid) a reaction pathway for DBS and a kinetic model in WAO were proposed. In the case of CWAO experiments, seventy-two hours tests were done in a fixed bed reactor in continuous trickle flow regime, using a commercial activated carbon (AC) as catalyst. The temperature and PO2 were 140-160deg. C and 2-9bar, respectively. The influence of the operating conditions on the DBS oxidation, the occurrence of oxidative coupling reactions over the AC, and the catalytic activity (in terms of substrate removal) were established. The results show that the AC without any supported active metal behaves bi-functional as adsorbent and catalyst, giving TOC conversions up to 52% at 160deg. C and 2 bar of PO2, which were comparable to those obtained in WAO experiments. Respirometric tests were completed before and after CWAO and to the main intermediates identified through the WAO and CWAO oxidation route. Then, the readily biodegradable COD (CODRB) of the CWAO and WAO effluents were found. Taking into account these results it was possible to compare whether or not the CWAO or WAO effluents were suitable for a conventional activated sludge plant inoculated with non adapted culture

  10. Catalytic and non-catalytic wet air oxidation of sodium dodecylbenzene sulfonate: Kinetics and biodegradability enhancement

    Energy Technology Data Exchange (ETDEWEB)

    Suarez-Ojeda, Maria Eugenia [Departament d' Enginyeria Quimica, Escola Tecnica Superior d' Enginyeria Quimica, Universitat Rovira i Virgili, Av. Paisos Catalans 26, 43007 Tarragona, Catalonia (Spain); Departament d' Enginyeria Quimica, Edifici Q-ETSE, Universitat Autonoma de Barcelona, 08193 Bellaterra, Barcelona, Catalonia (Spain); Kim, Jungkwon [Chemical Engineering and Analytical Sciences Department, University of Manchester, Manchester (United Kingdom); Carrera, Julian [Departament d' Enginyeria Quimica, Edifici Q-ETSE, Universitat Autonoma de Barcelona, 08193 Bellaterra, Barcelona, Catalonia (Spain); Metcalfe, Ian S. [Chemical Engineering and Advanced Materials Department, University of Newcastle upon Tyne, Newcastle upon Tyne (United Kingdom); Font, Josep [Departament d' Enginyeria Quimica, Escola Tecnica Superior d' Enginyeria Quimica, Universitat Rovira i Virgili, Av. Paisos Catalans 26, 43007 Tarragona, Catalonia (Spain)]. E-mail: jose.font@urv.cat

    2007-06-18

    Wet air oxidation (WAO) and catalytic wet air oxidation (CWAO) were investigated as suitable precursors for the biological treatment of industrial wastewater containing sodium dodecylbenzene sulfonate (DBS). Two hours WAO semi-batch experiments were conducted at 15bar of oxygen partial pressure (P{sub O{sub 2}}) and at 180, 200 and 220deg. C. It was found that the highest temperature provides appreciable total organic carbon (TOC) and chemical oxygen demand (COD) abatement of about 42 and 47%, correspondingly. Based on the main identified intermediates (acetic acid and sulfobenzoic acid) a reaction pathway for DBS and a kinetic model in WAO were proposed. In the case of CWAO experiments, seventy-two hours tests were done in a fixed bed reactor in continuous trickle flow regime, using a commercial activated carbon (AC) as catalyst. The temperature and P{sub O{sub 2}} were 140-160deg. C and 2-9bar, respectively. The influence of the operating conditions on the DBS oxidation, the occurrence of oxidative coupling reactions over the AC, and the catalytic activity (in terms of substrate removal) were established. The results show that the AC without any supported active metal behaves bi-functional as adsorbent and catalyst, giving TOC conversions up to 52% at 160deg. C and 2 bar of P{sub O{sub 2}}, which were comparable to those obtained in WAO experiments. Respirometric tests were completed before and after CWAO and to the main intermediates identified through the WAO and CWAO oxidation route. Then, the readily biodegradable COD (COD{sub RB}) of the CWAO and WAO effluents were found. Taking into account these results it was possible to compare whether or not the CWAO or WAO effluents were suitable for a conventional activated sludge plant inoculated with non adapted culture.

  11. A feasibility study of catalytic reduction method for tritium recovery from tritiated water

    International Nuclear Information System (INIS)

    Feasibility of catalytic reduction method for the application to the tritium recovery process in the fusion fuel cleanup system and the blanket tritium recovery system was studied by experimental work and the thermodynamic analysis. Reduction experiments of H2O vapor with Ar carrier were carried out under the following conditions: temperature; 350 -- 650 K, H2O vapor concentration in feed gas; 103 -- 104 ppm, mole ratio of CO to H2O; 1 -- 10, space velocity; 2 x 102 -- 2 x 104 hr-1. Catalyst was the mixture of CuO, ZnO and Cr2O3, which has been used as the catalyst for the water-gas shift reaction H2O(g) + CO(g) reversible H2(g) + CO2(g). Relations between the conversion factor for H2O vapor and the operating conditions such as temperature, feed composition and feed flow rate were obtained by the experiments. Catalytic reaction rate equation and the rate constants, which can be used for designing a practicable catalytic reduction bed, were also determined by the treatment of the second order reaction. Advantages of the tritium recovery system composed of the reduction bed and palladium diffusers were verified by the present experiments and the study of several tritium recovery systems. Very high recovery ratio will be obtained at low operation temperature by the systems. (author)

  12. 壳聚糖钯配合物磁微球的合成及其在催化丙烯酸与碘代苯反应中的性能%Synthesis of a magnetic-separated chitosan-palladium complex and its catalytic activity in the reaction of acrylic acid with iodobenzene

    Institute of Scientific and Technical Information of China (English)

    杨黎明; 张群飞; 陈捷; 曹芳琦; 戎亮; 曹春燕

    2008-01-01

    A magnetic-separated catalyst of chitosan-palladium complex (Fe3O4-CS-Pd) based on chitosan coated Fe3O4 microspheres was prepared by the "bottom-up" approach. The catalytic behavior of the catalyst in the cross coupling reaction of acrylic acid (AA) with iodobenzene (ArI) was investigated. Compared with the traditional homogeneous palladium catalysts, the catalyst was easily separated and reused.

  13. Some Armature Reaction Compensation Methods. Numerical Design of Experiments and Optimisation For a Hybrid Excitation Machine

    OpenAIRE

    Li LI; Foggia, Albert; Kedous-Lebouc, Afef; Mipo, Jean-Claude; Kobylanski, Luc

    2009-01-01

    This paper presents a hybrid excitation synchronous machine which combines a permanent magnet excitation with a wound field one. With two sources of flux, this kind of machines is cited more and more frequently in vehicle application for easier control of flux. After a brief description of the structure, some methods will be presented to improve the performances of this machine. Simulation results have shown that the armature reaction has a magnetizing effect when it enters in a pole face and...

  14. Data Pre-Processing for Label-Free Multiple Reaction Monitoring (MRM) Experiments

    OpenAIRE

    Chung, Lisa M.; Colangelo, Christopher M.; Hongyu Zhao

    2014-01-01

    Multiple Reaction Monitoring (MRM) conducted on a triple quadrupole mass spectrometer allows researchers to quantify the expression levels of a set of target proteins. Each protein is often characterized by several unique peptides that can be detected by monitoring predetermined fragment ions, called transitions, for each peptide. Concatenating large numbers of MRM transitions into a single assay enables simultaneous quantification of hundreds of peptides and proteins. In recognition of the i...

  15. Parallel Reaction Monitoring: A Targeted Experiment Performed Using High Resolution and High Mass Accuracy Mass Spectrometry

    Directory of Open Access Journals (Sweden)

    Navin Rauniyar

    2015-12-01

    Full Text Available The parallel reaction monitoring (PRM assay has emerged as an alternative method of targeted quantification. The PRM assay is performed in a high resolution and high mass accuracy mode on a mass spectrometer. This review presents the features that make PRM a highly specific and selective method for targeted quantification using quadrupole-Orbitrap hybrid instruments. In addition, this review discusses the label-based and label-free methods of quantification that can be performed with the targeted approach.

  16. Low amplitude insult project: PBX 9501 high explosive violent reaction experiments

    Energy Technology Data Exchange (ETDEWEB)

    Idar, D.J.; Lucht, R.A.; Straight, J.W.; Scammon, R.J.; Browning, R.V.; Middleditch, J.; Dienes, J.K.; Skidmore, C.B.; Buntain, G.A.

    1998-12-31

    The Modified Steven test geometry has been used with several different target designs to investigate the mechanical loading behavior of PBX 9501 to a low velocity impact. A 2 kg. mild steel spigot projectile is launched via a new powder driven gun design, from {approximately} 20 to 105 m/s, at lightly confined, steel targets. Brief descriptions of the gun design and operation are given. The threshold velocity to reaction for various target designs, different PBX 9501 lots, and different high explosive (HE) thicknesses are reported and compared. Various diagnostics have been employed to evaluate the pressure profile and timing, and target strain behavior relative to projectile impact. The violence of reaction, as measured by both passive and active techniques, is reported relative to a steady state detonation in PBX 9501. Experimental results suggest slightly different ignition mechanisms dominate based on (HE) thickness, resulting in delayed reactions from {approximately} 0.2- to 2.8-ms after impact. Post-test analyses of the PBX 9501 are briefly summarized.

  17. Synthesis of 1D Fe₃O₄/P(MBAAm-co-MAA) nanochains as stabilizers for Ag nanoparticles and templates for hollow mesoporous structure, and their applications in catalytic reaction and drug delivery.

    Science.gov (United States)

    Zhang, Wei; Si, Xiaowei; Liu, Bin; Bian, Guomin; Qi, Yonglin; Yang, Xinlin; Li, Chenxi

    2015-10-15

    One-dimensional (1D) magnetic Fe3O4/P(MBAAm-co-MAA) nanochains were prepared by distillation-precipitation polymerization of MBAAm and MAA in the presence of Fe3O4 nanoparticles as building blocks under a magnetic heating stirrer, which played two critical roles: serving as magnetic field to induce the self-assembly of Fe3O4 nanoparticles into 1D nanochains and providing thermal energy to induce the polymerization of MAA and MBAAm on the surface of the Fe3O4 nanoparticles. The thickness of the P(MBAAm-co-MAA) layer can be easily tuned by adjusting the successive polymerization steps. The polymer layer that contained carboxyl groups was used as stabilizers for loading Ag nanoparticles and the reaction locus for deposition of outer silica layer via a sol-gel method in presence of C18TMS as the pore directing agent for tri-layer nanochains. The corresponding hollow mesoporous silica nanochains with movable maghemite cores (γ-Fe2O3@mSiO2) were produced after removal of the polymer mid-layer and the alkyl groups of the pore directing agent via calcination of the tri-layer nanochains at high temperature. The Fe3O4/P(MBAAm-co-MAA)/Ag nanochains exhibited a highly catalytic efficiency and well reusable property toward the reduction of nitrophenol. Furthermore, the γ-Fe2O3@mSiO2 nanochains possessed hollow mesoporous structure and high specific surface area (197.2 m(2) g(-1)) were used as a drug carrier, which displayed a controlled release property. PMID:26119084

  18. Atmospheric Pressure Microwave Assisted Heterogeneous Catalytic Reactions

    Directory of Open Access Journals (Sweden)

    Ken Belmore

    2007-07-01

    Full Text Available The newly synthesized 5,10,15,20-tetra[3-(3-trifluoromethylphenoxy]porphyrin, TTFMPP, has been characterized using mass spectroscopy, 1H-, 13C- and 19F-NMR, MALDI-TOF mass spectrometry, UV-Vis and fluorescence spectrophotometry, andcyclic voltammetry. The NMR confirmed the structure of the compound and the massspectrum was in agreement with the proposed molecular formula. The UV-Vis absorptionspectrum of TTFMPP shows characteristic spectral patterns similar to those of tetraphenylporphryin, with a Soret band at 419 nm and four Q bands at 515, 550, 590, and 648 nm.Protonation of the porphyrin with TFA resulted in the expected red shift of the Soret band.Excitation at 419 nm gave an emission at 650 nm. The quantum yield of the porphyrin wasdetermined to be 0.08. Cyclic voltammetry was used to determine the oxidation andreduction potentials of the new porphyrin. Two quasi-reversible one-electron reductions at–1.00 and –1.32 V and a quasi-reversible oxidation at 1.20 V versus the silver/silverchloride reference electrode with tetrabutylammonium tetrafluoroborate as the supportingelectrolyte in methylene chloride were observed.

  19. Charge-exchange and fusion reaction measurements during compression experiments with neutral beam heating in the Tokamak Fusion Test Reactor

    International Nuclear Information System (INIS)

    Adiabatic toroidal compression experiments were performed in conjunction with high power neutral beam injection in the Tokamak Fusion Test Reactor (TFTR). Acceleration of beam ions to energies nearly twice the injection energy was measured with a charge-exchange neutral particle analyzer. Measurements were also made of 2.5 MeV neutrons and 15 MeV protons produced in fusion reactions between the deuterium beam ions and the thermal deuterium and 3He ions, respectively. When the plasma was compressed, the d(d,n)3He fusion reaction rate increased a factor of five, and the 3He(d,p)4He rate by a factor of twenty. These data were simulated with a bounce-averaged Fokker-Planck program, which assumed conservation of angular momentum and magnetic moment during compression. The results indicate that the beam ion acceleration was consistent with adiabatic scaling

  20. Simulation Experiments on the Reaction of CH4-CaSO4 and Its Carbon Kinetic Isotope Fractionation

    Institute of Scientific and Technical Information of China (English)

    YueChangtao; LiShuyuan; DingKangle; ZhongNingning

    2005-01-01

    Thermochemical sulfate reduction (TSR) in geological deposits can account for the accumulation of H,S in deep sour gas reservoirs. In this paper, thermal simulation experiments on the reaction of CH4-CaSO4 were carried out using an autoclave at high temperatures and high pressures. The products were characterized with analytical methods including carbon isotope analysis. It is found that the reaction can proceed to produce H2S, H2O and CaCO3 as the main products. Based on the experimental results, the carbon kinetic isotope fractionation was investigated, and the value of Ki(kinetic isotope effect) was calculated. The results obtained in this paper can provide useful information to explain the occurrence of H2S in deep carbonate gas reservoirs.

  1. Study and Analysis on Naphtha Catalytic Reforming Reactor Simulation

    Institute of Scientific and Technical Information of China (English)

    Liang Ke min; Song Yongji; Pan Shiwei

    2004-01-01

    A naphtha catalytic reforming unit with four reactors connected in series is analyzed. A physical model is proposed to describe the catalytic reforming radial flow reactor. Kinetics and thermodynamics equations are selected to describe the naphtha catalytic reforming reaction characteristics based on idealizing the complex naphtha mixture to represent the paraffin, naphthene, and aromatic groups with individual compounds. The simulation results based on above models agree very well with actual operating data of process unit.

  2. Beta Decay of Tz=-1 nuclei and Comparison with Charge Exchange Reaction Experiments

    OpenAIRE

    Molina Palacios, Francisco Gabriel

    2011-01-01

    This thesis covers an experimental study of the beta-decay of four Tz=-1 nuclei. The main purpose of this work is to compare these four decays with the mirror process studied in the (3He,t) charge exchange (CE) reaction at RCNP in Osaka, Japan. The experimental work was carried out at two different laboratories, LISOL at the Centre de Recherches du Cyclotron CRC in Louvain-la-Neuve, Belgium and RISING-FRS at the Gesellschaft f¿ur SchwerIonenforschung (GSI) in Darmstadt, Germany. The two fa...

  3. Analysis of the PROTEUS reaction rate experiments with the ENDF/B-VI library

    International Nuclear Information System (INIS)

    The analysis of the PROTEUS Core 1 reaction rates with ENDF/B-VI show that there have been good progress concerning plutonium isotopes nuclear data (mainly Pu 239). In addition to that, there has been an excellent agreement of the parameter C8 which demonstrate the good quality of the U-238 (n, γ) nuclear data as well as the methodology used in this work. The analysis of the two-rod heterogeneity factor indicates the necessity of the introduction of the calculational methodologies which treats the geometric aspect exactly as MCNP. (author). 15 refs, 2 figs, 5 tabs

  4. Looking for the GAP effect in manual responses and the role of contextual influences in reaction time experiments

    Directory of Open Access Journals (Sweden)

    Faria Jr. A.J.P.

    2004-01-01

    Full Text Available When the offset of a visual stimulus (GAP condition precedes the onset of a target, saccadic reaction times are reduced in relation to the condition with no offset (overlap condition - the GAP effect. However, the existence of the GAP effect for manual responses is still controversial. In two experiments using both simple (Experiment 1, N = 18 and choice key-press procedures (Experiment 2, N = 12, we looked for the GAP effect in manual responses and investigated possible contextual influences on it. Participants were asked to respond to the imperative stimulus that would occur under different experimental contexts, created by varying the array of warning-stimulus intervals (0, 300 and 1000 ms and conditions (GAP and overlap: i intervals and conditions were randomized throughout the experiment; ii conditions were run in different blocks and intervals were randomized; iii intervals were run in different blocks and conditions were randomized. Our data showed that no GAP effect was obtained for any manipulation. The predictability of stimulus occurrence produced the strongest influence on response latencies. In Experiment 1, simple manual responses were shorter when the intervals were blocked (247 ms, P < 0.001 in relation to the other two contexts (274 and 279 ms. Despite the use of choice key-press procedures, Experiment 2 produced a similar pattern of results. A discussion addressing the critical conditions to obtain the GAP effect for distinct motor responses is presented. In short, our data stress the relevance of the temporal allocation of attention for behavioral performance.

  5. Proposal of an experiment about Λ - n interaction via FSI in γ + d reaction at ELPH, Tohoku University

    Science.gov (United States)

    Kaneta, Masashi; NKS2 Collaboration

    2014-09-01

    The experiment of strangeness photo-production, NKS2, has been carried out at Research Center for Electron Photon Science (ELPH), Tohoku University. We had focused on the neutral channel near the threshold and reported K0 and Lambda differential cross section of γ + d reaction in that energy region. ELPH started to provide the real photon beam from a 1.3 GeV electron synchrotron after recovering from the damage of the Great East Japan Earthquake. As the prospect of the next experiment, we are planning to measure Λ - n interaction via γ + d -->K+ + Λ + n . Theoretical studies predict that the K+ cross section enhanced only near the threshold region due to FSI of Λ + n in γ + d reaction comparing to γ + p . NKS2 has an acceptance in forward angle and covers almost full kinematic region. The characteristics give us an advantage of experiment, that is, not only K+ but also K+ Lambda coincidence measurement. Additionally, the gamma beam provided (maximum: 1.25 GeV) is suitable for the strangeness photo production in the threshold region (0.9 GeV in lab). We will present a capability of measurement for Λ + n interaction using the NKS2 spectrometer at ELPH.

  6. Numerical study of chemical reactions in a surface microdischarge tube with mist flow based on experiment

    Science.gov (United States)

    Shibata, T.; Nishiyama, H.

    2014-03-01

    Recently, a water treatment method of spraying solution into a discharge region has been developed and shows high energy efficiency. In this study, a simulation model of a water treatment method using a surface microdischarge (SMD) tube with mist flow is proposed for further understanding the detailed chemical reactions. Our model has three phases (plasma, gas and liquid) and three simulation steps. The carrier gas is humid air including 2% or 3% water vapour. The chemical species diffusion characteristics in the SMD tube and the concentrations in a droplet are clarified in a wide pH interval. The simulation results show that the chemical species generated on the SMD tube inner wall are diffused to the central axis and dissolved into fine droplets. Especially, OH radicals dissolve into droplets a few mm away from the SMD tube wall because of acidification of the droplets. Furthermore, the hydrogen peroxide density, which is the most important indicator of a radical reaction in water, is influenced by the initial solution pH. This pH dependence results from ozone self-decomposition in water.

  7. Fast γ-ray coincidence timing using a BGO detector array in a nuclear reaction experiment

    International Nuclear Information System (INIS)

    The (7Li, 7Be) nuclear charge-exchange reaction has been investigated at E(7Li)=350 MeV. Coincidences were measured between the charged 7Be reaction products in the focal plane of a magnetic spectrometer and 430-keV Doppler-shifted γ-rays from the decay in flight of excited 7Be ejectiles. The latter were detected in a compact BGO detector array. Fast timing was used to optimize the separation between prompt and randoms events. The BGO output signals display the statistical distribution of the arrival times of individual photoelectrons from the photocathode in the photomultiplier tubes. A timing resolution of 6.5 ns relative to the accelerator RF was obtained. A simple model was successfully developed to simulate the BGO output signals with a statistical distribution of a predetermined number of photoelectrons modulated by the light output response of the scintillator and the single-photoelectron gain distribution and transit time through the photomultiplier tube. It is concluded that the timing resolution is primarily limited by the small number of photoelectrons. ((orig.))

  8. Implementation of BIRADSTM together with an organization of percutaneous breast biopsies: experiences, reactions

    International Nuclear Information System (INIS)

    Purpose: To record the acceptance and reactions of radiologist und physicians who recommend patients for mammography after simultaneous establishment of BIRADSTM and a registration of the results of percutaneous breast biopsies. Materials and methods: To improve clarity of mammographic reports and to provide guidance concerning any necessary percutaneous breast biopsies the Breast Imaging Data And Reporting System (BIRADSTM) has been introduced regionally together with a registration of percutaneous breast biopsies. Using a questionnaire, 25 radiologists and 230 referring physicians were asked on acceptance and reactions concerning the established system. Results: Of the 15 answering radiologists, 93% considered BIRADSTM a worthwhile effort and 87% found the biopsy guidelines to be useful. They regarded the acceptance of the referring physicians and patients as high (80%). Up to 69% of the 52 participating physicians stated a better understanding of the mammographic reports, an easier comprehension of the dignity classification of a mammographic lesion and the feeling of an improvement in their work. Preoperative assessment of histology was found to be valuable by 94% of the referring physicians. They believe that more than half of the patients benefit from the biopsy guidelines and that the majority of patients accept this approach. Conclusion: BIRADSTM is useful to standardize and improve mammographic reports. It is advantageous to link BIRADSTM with guidelines for percutaneous breast biopsies. (orig.)

  9. 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

  10. Partial gravity reaction experiment sysytem on graund using multi-Copter

    Science.gov (United States)

    Hasegawa, Katsuya; Maeda, Naoko

    2016-07-01

    In order to enable further space exploration into the space, Moon, Mars, and other planets, it is essential to understand the physiological response to low gravity environments. However, We made low gravity environment for studies using the satellite parabolic flight and drop tower. It is very expensive experiment that low gravity physiological response. Because, it requires rockets and airplanes and dedicated Tower, low gravity conditions test have not been conducted sufficiently due to the extraordinary high cost for conducting experiments. The study present is to develop the radio-controlled multicopter system that is used for the controlled falling flight vehicle (not free fall). During the controlled falling, the payload is exposed to a certain level of low gravity. 1) G profile: low gravity from 0 g to 1 g that will last approximately 5seconds, 50 kg. 2) Supply limited imaging techniques, high-speed or normal video and X ray images. 3) Wireless transmission of up to 64 channels of analog and digital signals. This vehicle is designed for experimentation on various model organisms, from cells to animals and plants. The multicopter flight system enables conducting experiments in low gravity conditions with less than 1% of the budget for spaceflight or parabolic flights. Experiment is possible to perform repeated many times in one day. We can expect reproducible results from many repeated trials at the lowest cost.

  11. On the Use of Interactive Texts in Undergraduate Chemical Reaction Engineering Courses: A Pedagogical Experience

    Science.gov (United States)

    Asensio, Daniela A.; Barassi, Francisca J.; Zambon, Mariana T.; Mazza, Germán D.

    2010-01-01

    This paper describes the results of a pedagogical experience carried out at the University of Comahue, Argentina, with an interactive text (IT) concerning Homogeneous Chemical Reactors Analysis. The IT was built on the frame of the "Mathematica" software with the aim of providing students with a robust computational tool. Students'…

  12. Statistical Models for the Analysis and Design of Digital Polymerase Chain Reaction (dPCR) Experiments.

    Science.gov (United States)

    Dorazio, Robert M; Hunter, Margaret E

    2015-11-01

    Statistical methods for the analysis and design of experiments using digital PCR (dPCR) have received only limited attention and have been misused in many instances. To address this issue and to provide a more general approach to the analysis of dPCR data, we describe a class of statistical models for the analysis and design of experiments that require quantification of nucleic acids. These models are mathematically equivalent to generalized linear models of binomial responses that include a complementary, log-log link function and an offset that is dependent on the dPCR partition volume. These models are both versatile and easy to fit using conventional statistical software. Covariates can be used to specify different sources of variation in nucleic acid concentration, and a model's parameters can be used to quantify the effects of these covariates. For purposes of illustration, we analyzed dPCR data from different types of experiments, including serial dilution, evaluation of copy number variation, and quantification of gene expression. We also showed how these models can be used to help design dPCR experiments, as in selection of sample sizes needed to achieve desired levels of precision in estimates of nucleic acid concentration or to detect differences in concentration among treatments with prescribed levels of statistical power. PMID:26436653

  13. CO2 laser experiments using nuclear reactions as the ionization source.

    Science.gov (United States)

    Rhoads, H. S.; Schneider, R. T.; Allario, F.

    1971-01-01

    Experimental studies show that the output of a CO2 laser is significantly increased by products of the nuclear reaction He-3 (n,p)T. Helium-3 was used in lieu of the natural helium normally present in the 1:1:8 CO2:N2:He laser gas mixture (pressure = 6 torr). The laser assembly was then exposed to a reactor thermal neutron flux of about 100 million neutrons/sq cm/sec. Power output of the laser doubled while the electrical power input decreased; electrical efficiency was thus more than doubled. Results indicate that additional ionization by the energetic charged particles may be responsible for the improved laser performance.

  14. Experiments to Determine Neighborhood Reactions to Light Airplanes With and Without External Noise Reduction

    Science.gov (United States)

    Elwell, Fred S

    1953-01-01

    The work reported was part of a program of experimentation with external noise reduction on light airplanes. This particular study was in effect a byproduct survey conceived to utilize already available equipment and personnel to further the findings of the original research and to determine reactions in populated neighborhoods to light aircraft with and without noise-reduction equipment. The findings indicate that at the 10 sites within and about metropolitan Boston the degree of noise reduction previously found to be aerodynamically and structurally feasible did eliminate substantially all neighborhood objections to noise per se. The evidence clearly suggests that, when the noise nuisance is minimized to the extent found feasible, the number and severity of other objections also diminish -- evidently because the flight operations are noticed less when heard less.

  15. Wavefronts in time-delayed reaction-diffusion systems. Theory and comparison to experiment

    Energy Technology Data Exchange (ETDEWEB)

    Fort, Joaquim [Departament de Fisica, Universitat de Girona, Girona (Spain)]. E-mail: joaquim.fort@udg.es; Mendez, Vicenc [Facultat de Ciencies de la Salut, Universitat Internacional de Catalunya, Ssant Cugat del Valles (Spain)]. E-mail: vmendez@csc.unica.edu

    2002-06-01

    We review the recent theoretical progress in the formulation and solution of the front speed problem for time-delayed reaction-diffusion systems. Most of the review is focused on hyperbolic equations. They have been widely used in recent years, because they allow for analytical solutions and yield a realistic description of some relevant phenomena. The theoretical methods are applied to a range of applications, including population dynamics, forest fire models, bistable systems and combustion wavefronts. We also present a detailed account of successful predictions of the models, as assessed by comparison to experimental data for some biophysical systems, without making use of any free parameters. Areas where the work reviewed may contribute to future progress are discussed. (author)

  16. High energy electrons, positrons and photonuclear reactions in petawatt laser-solid experiments

    Energy Technology Data Exchange (ETDEWEB)

    Cowan, T E; Hunt, A W; Johnson, J; Perry, M D; Fountain, W; Hatchett, S; Key, M H; Kuehl, T; ; Parnell, T; Pennington, D M; Phillips, T W; Roth, M; Takahashi, Y; Wilks, S C

    1999-09-09

    The Petawatt laser at LLNL has opened a new regime of high-energy laser-matter interactions in which the quiver motion of plasma electrons is fully relativistic with energies extending well above the threshold for nuclear processes. We have observed that, in addition to the large flux of several MeV electrons ponderomotively expelled from the ultra-intense laser focus, there is a high energy component of electrons extending to -100 MeV, apparently from relativistic self-focusing and plasma acceleration in the underdense pre-formed plasma. The generation of hard bremsstrahlung cascade as these electrons traverse the solid target material, and the resulting photo-nuclear reactions, nuclear fission, and positron-electron pair production are described.

  17. Homogeneous catalytic wet air oxidation for the treatment oftextile wastewaters

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    An extensive series of experiments was carried out in order to identify suitable catalysts to boost the reaction rate of wet air oxidation of real textile wastewaters at relatively mild temperature and pressure. Experimental results indicated that all catalysts tested in this investigation had shown an impressive increase in the initial COD and TOC removal rate as well as the COD and TOC removal levels in two hours reaction. Among all the catalysts tested, copper salts were more effective than the rest. Anions of the salt soluffonsalso played a role in the catalytic process with nitrate ions having better effect than sulfate ions. Hence copper nitrates were more effective than copper sulfates. It was also found that a mixture of salts with different metals performed better than either of the component single salt alone.

  18. Catalytic production of biodiesel

    Energy Technology Data Exchange (ETDEWEB)

    Theilgaard Madsen, A.

    2011-07-01

    The focus of this thesis is the catalytic production of diesel from biomass, especially emphasising catalytic conversion of waste vegetable oils and fats. In chapter 1 an introduction to biofuels and a review on different catalytic methods for diesel production from biomass is given. Two of these methods have been used industrially for a number of years already, namely the transesterification (and esterification) of oils and fats with methanol to form fatty acid methyl esters (FAME), and the hydrodeoxygenation (HDO) of fats and oils to form straight-chain alkanes. Other possible routes to diesel include upgrading and deoxygenation of pyrolysis oils or aqueous sludge wastes, condensations and reductions of sugars in aqueous phase (aqueous-phase reforming, APR) for monofunctional hydrocarbons, and gasification of any type of biomass followed by Fischer-Tropsch-synthesis for alkane biofuels. These methods have not yet been industrialised, but may be more promising due to the larger abundance of their potential feedstocks, especially waste feedstocks. Chapter 2 deals with formation of FAME from waste fats and oils. A range of acidic catalysts were tested in a model fat mixture of methanol, lauric acid and trioctanoin. Sulphonic acid-functionalised ionic liquids showed extremely fast convertion of lauric acid to methyl laurate, and trioctanoate was converted to methyl octanoate within 24 h. A catalyst based on a sulphonated carbon-matrix made by pyrolysing (or carbonising) carbohydrates, so-called sulphonated pyrolysed sucrose (SPS), was optimised further. No systematic dependency on pyrolysis and sulphonation conditions could be obtained, however, with respect to esterification activity, but high activity was obtained in the model fat mixture. SPS impregnated on opel-cell Al{sub 2}O{sub 3} and microporous SiO{sub 2} (ISPS) was much less active in the esterification than the original SPS powder due to low loading and thereby low number of strongly acidic sites on the

  19. Catalytic performance of heteroatom-modified carbon nanotubes in advanced oxidation processes

    Institute of Scientific and Technical Information of China (English)

    João Restivo; Raquel P. Rocha; Adrián M. T. Silva; José J. M. Órfão; Manuel F. R. Pereira; José L. Figueiredo

    2014-01-01

    Multi-walled carbon nanotubes (CNTs) were submitted to chemical and thermal treatments in or-der to incorporate different heteroatoms on the surface. O-, S-and N-containing groups were suc-cessfully introduced onto the CNTs without significant changes of the textural properties. The cata-lytic activity of these heteroatom-modified CNTs was studied in two liquid phase oxidation pro-cesses:catalytic ozonation and catalytic wet air oxidation (CWAO), using oxalic acid and phenol as model compounds. In both cases, the presence of strongly acidic O-containing groups was found to decrease the catalytic activity of the CNTs. On the other hand, the introduction of S species (mainly sulfonic acids) enhanced the removal rate of the model compounds, particularly in the CWAO of phenol. Additional experiments were performed with a radical scavenger and sodium persulfate, in order to clarify the reaction mechanism. Nitrogen functionalities improve the catalytic performance of the original CNTs, regardless of the process or of the pollutant.

  20. Synthesis of Borohydride and Catalytic Dehydrogenation by Hydrogel Based Catalyst

    Science.gov (United States)

    Boynuegri, Tugba Akkas; Karabulut, Ahmet F.; Guru, Metin

    2016-08-01

    This paper deals with the synthesis of calcium borohydride (Ca(BH4)2) as hydrogen storage material. Calcium chloride salt (CaCl2), magnesium hydride (MgH2), and boron oxide (B2O3) were used as reactants in the mechanochemical synthesis of Ca(BH4)2. The mechanochemical reaction was carried out by means of Spex type ball milling without applying high pressure and temperature. Parametric studies have been established at different reaction times and for different amounts of reactants at a constant ball to powder ratio (BPR) 4:1. The best combination was determined by Fourier Transform Infrared (FT-IR) analysis. According to the FT-IR analysis, reaction time, the first reaction parameter, was found as 1600 min. After the reaction time was fixed at 1600 min, the difference of the B-H peak areas was dependent on the amount of reactant MgH2 that was investigated. The amount of the reactant (MgH2), the second reaction parameter, was measured to be 2.85 times more than the stoichiometric amount of MgH2. According to our previous studies, BPR was selected as 4:1 for all experiments. Samples were prepared in a glove box under argon atmosphere but the time that elapsed for FT-IR analysis highly affected B-H bonds. B-H peak areas clearly decreased with time because of negative effect of ambient atmosphere. A catalyst was prepared by absorbing cobalt fluoride (CoF2) in poly (acrylamide-co-acrylic acid) hydrogel matrices type and its catalytic dehydrogenation performance that has been characterized by the catalytic reaction of sodium borohydride's known hydrogen capacity in an alkaline medium. The metal amount of hydrogel catalyst was determined as 135.82 mg Co by Atomic Absorption Spectroscopy (AAS). The specific dehydrogenation capacity of the Co active compound in the catalyst thanks to catalytic dehydrogenation of commercial sodium borohydride was measured as 1.66 mL H2/mg Co.