WorldWideScience

Sample records for base metal-palladium catalytic

  1. Novel Base Metal-Palladium Catalytic Diesel Filter Coating with NO2 Reducing Properties

    DEFF Research Database (Denmark)

    Johansen, K.; Dahl, S.; Mogensen, G.;

    2007-01-01

    price structure. The novel base metal/palladium catalytic coat has been applied on commercial silicon carbide wall flow diesel filters and tested in an engine test bench. Results from engine bench tests concerning soot combustion, HC-, CO-, NO2- removal with the novel coat will are compared to present...

  2. The influence of ethylenediamine tetra acetic acid (EDTA) on the transformation and solubility of metallic palladium and palladium(II) oxide in the environment.

    Science.gov (United States)

    Zereini, Fathi; Wiseman, Clare L S; Vang, My; Albers, Peter; Schneider, Wolfgang; Schindl, Roland; Leopold, Kerstin

    2015-05-01

    The environmental occurrence of elevated concentrations of platinum (Pt), palladium (Pd) and rhodium (Rh) from automotive catalytic converters has been well-documented. Limited information exists regarding their chemical behavior post-emission, however, especially in the presence of commonly occurring complexing agents. The purpose of this study is to examine the influence of ethylenediamine tetra acetic acid (EDTA) on the possible environmental transformation and solubility of Pd by conducting batch experiments using metallic palladium (Pd black) and palladium(ii) oxide (PdO). Changes in the particle surface chemistry of treated samples were analyzed using X-ray Photoelectron Spectroscopy (XPS) and Transition Electron Microscopy/Energy Dispersive X-ray Spectrometry (TEM/EDX) techniques. Metallic palladium was partially transformed into PdOx (x environmental immobility of Pd, small amounts of this element emitted in metallic form are likely to be soluble in the presence of complexing agents such as EDTA.

  3. Effects of nanosized metallic palladium loading and calcination on characteristics of composite silica

    Institute of Scientific and Technical Information of China (English)

    吴玉程; 吴侠; 李广海; 张立德

    2003-01-01

    In order to investigate the effects of nanosized metallic palladium loading and calcination on the characteristics of composite silica,the silica was prepared by sol-gel technique,leading to an amorphous solid with mesoporosity,and the pore size distribution is narrow,centered at 3-5 nm.The composite silica was formed by impregnating palladium precursor into the porous network with sequel calcination in hydrogen.The results show that the nanosized palladium as guest phase in the composite silica is subjected to the mesoporous structure and calcination,resulting in the changes of optical adsorption that red-shifted to higher wavelength with the palladium loading and the heating temperature.The tailoring of the optical properties can be ascribed to the effect of the nanosized metal particles and interactions occurred between palladium and silica.

  4. EFFECTS OF FINELY DISPERSED METALLIC PALLADIUM ON MICROSTRUCTURE AND PROPERTIES OF NANOCOMPOSITES PRODUCED BY SOL-GEL TECHNIQUE

    Institute of Scientific and Technical Information of China (English)

    Yucheng Wu; Yong Zhang; Lide Zhang

    2004-01-01

    Nanosized palladium particles were incorporated into mesoporous silica matrix to obtain nanocomposites using the sol-gel technique. Effects of the finely dispersed metallic palladium on the microstructure and properties of the nanocomposites were investigated. By means of X-ray diffraction and optical absorption, it was found that palladium particles were 5~9 nm in diameter and their uniform dispersion in the mesoporous silica depended on both the content of the palladium and the structural features of the silica matrix. The results showed that the mixing method of preparation led to wider size distribution of the nanosized particles as compared to the immersion method, but dispersed degree was reduced. Although the incorporation of nanosized palladium particles could not substantially induce significant structural changes of the matrix, the apparent red-shifted optical absorptions for the nanocomposites were observed as compared to the parent monolithic silica, particularly with increase in palladium loading and calcination temperature.

  5. Synthesis and catalytic application of amino acid based dendritic macromolecules

    NARCIS (Netherlands)

    Koten, G. van; Gossage, R.A.; Jastrzebski, J.T.B.H.; Ameijde, J. van; Mulders, S.J.E.; Brouwer, Arwin J.; Liskamp, R.M.J.

    1999-01-01

    The use of amino acid based dendrimers as molecular scaffolds for the attachment of catalytically active organometallic Ni ''pincer'' complexes, via a urea functionality, is described; the dendrimer catalysts have comparable activity to their mononuclear (NCN)NiX analogues.

  6. Catalytic flash pyrolysis of oil-impregnated-wood and jatropha cake using sodium based catalysts

    NARCIS (Netherlands)

    Ali Imran, A.; Bramer, E.A.; Seshan, K.; Brem, G.

    2016-01-01

    Catalytic pyrolysis of wood with impregnated vegetable oil was investigated and compared with catalytic pyrolysis of jatropha cake making use of sodium based catalysts to produce a high quality bio-oil. The catalytic pyrolysis was carried out in two modes: in-situ catalytic pyrolysis and post treatm

  7. Acid-base bifunctional catalytic surfaces for nucleophilic addition reactions.

    Science.gov (United States)

    Motokura, Ken; Tada, Mizuki; Iwasawa, Yasuhiro

    2008-09-01

    This article illustrates the modification of oxide surfaces with organic amine functional groups to create acid-base bifunctional catalysts, summarizing our previous reports and also presenting new data. Immobilization of organic amines as bases on inorganic solid-acid surfaces afforded highly active acid-base bifunctional catalysts, which enabled various organic transformations including C--C coupling reactions, though these reactions did not proceed with either the homogeneous amine precursors or the acidic supports alone. Spectroscopic characterization, such as by solid-state MAS NMR and FTIR, revealed not only the interactions between acidic and basic sites but also bifunctional catalytic reaction mechanisms.

  8. Catalytic liquid marbles: Ag nanowire-based miniature reactors for highly efficient degradation of methylene blue.

    Science.gov (United States)

    Miao, Yue-E; Lee, Hiang Kwee; Chew, Wee Shern; Phang, In Yee; Liu, Tianxi; Ling, Xing Yi

    2014-06-04

    Ag nanowire-based catalytic liquid marbles are fabricated as miniature reactors, which demonstrate highly efficient, support-free and rate-controllable heterogeneous degradation of methylene blue, with catalytic efficiency close to 100%. Our miniature catalytic liquid marbles are essential for reactions involving highly toxic/hazardous or costly reactants, where small volume preliminary reactions are preferred.

  9. Silicon- and tin-based cuprates: now catalytic in copper!

    Science.gov (United States)

    Weickgenannt, Andreas; Oestreich, Martin

    2010-01-11

    Silicon- and tin-containing molecules are versatile building blocks in organic synthesis. A stalwart method for their preparation relies on the stoichiometric use of silicon- and tin-based cuprates, although a few copper(I)-catalyzed or even copper-free protocols have been known for decades. In this Concept, we describe our efforts towards copper(I)-catalyzed carbon--silicon and also carbon--tin bond formations using soft bis(triorganosilyl) and bis(triorganostannyl) zinc reagents as powerful sources of nucleophilic silicon and tin. Conjugate addition, allylic substitution, and carbon--carbon multiple bond functionalization is now catalytic in copper!

  10. Catalytic Transformation of Ethylbenzene over Y-Zeolite-based Catalysts

    KAUST Repository

    Al-Khattaf, Sulaiman

    2008-11-19

    Catalytic transformation of ethylbenzene (EB) has been investigated over ultrastable Y (USY)-zeolite-based catalysts in a novel riser simulator at different operating conditions. The effect of reaction conditions on EB conversion is reported. The USY catalyst (FCC-Y) was modified by steaming to form a significantly lower acidity catalyst (FCC-SY). The current study shows that the FCC-SY catalyst favors EB disproportionation more than cracking. A comparison has been made between the results of EB conversion over the lowly acidic catalyst (FCC-SY) and the highly acidic catalyst (FCC-Y) under identical conditions. It was observed that increase in catalyst acidity favored cracking of EB at the expense of disproportionation. Kinetic parameters for EB disappearance during disproportionation reaction over the FCC-SY catalyst were calculated using the catalyst activity decay function based on time on stream (TOS). © 2008 American Chemical Society.

  11. Catalytic systems of cumene oxidation based on multiwalled carbon nanotubes

    Science.gov (United States)

    Kobotaeva, N. S.; Skorokhodova, T. S.; Ryabova, N. V.

    2015-03-01

    Catalytic systems for cumene oxidation were prepared on the basis of silver-activated carbon nanotubes. Silver lies on the surface of the carbon nanotubes in the nanocrystalline state and has a size of 15-20 nm. The use of the obtained catalytic systems in cumene oxidation with molecular oxygen allowed a considerable decrease in the oxidation temperature and an increase in selectivity.

  12. MEMS-based fuel cells with integrated catalytic fuel processor and method thereof

    Science.gov (United States)

    Jankowski, Alan F.; Morse, Jeffrey D.; Upadhye, Ravindra S.; Havstad, Mark A.

    2011-08-09

    Described herein is a means to incorporate catalytic materials into the fuel flow field structures of MEMS-based fuel cells, which enable catalytic reforming of a hydrocarbon based fuel, such as methane, methanol, or butane. Methods of fabrication are also disclosed.

  13. Catalytic sensor based continuous emissions monitor in boiler applications

    Energy Technology Data Exchange (ETDEWEB)

    Schubert, P.F.; Devita, S.P.; Budd, A. [Monitor Labs, Inc., Englewood, CO (United States)

    1997-12-31

    Until the development of reliable, solid state NO{sub x} sensors, sensor based continuous monitoring of NO{sub x} emissions was primarily by predictive or parametric methods which use data collected from other types of sensors to predict what a NO{sub x} sensor would read. While some success has been achieved using these methods, direct measurement of desired exhaust gases provides greater confidence than can be achieved using modeling approaches. The recent development of a solid state catalytic NO{sub x} sensor allowed development of an analyzer combining the advantages of sensors with the direct measurement capability of traditional continuous emissions monitors. The new sensor based analyzer, the CEMcat{trademark} continuous emissions monitor, utilizes a single, compact, sensor module containing the three sensors for NO{sub x}, CO and O{sub 2} measurement. Its development was sponsored by the Gas Research Institute (GRI), and additional support was provided by the Southern California Gas Co. The use of the CEMcat analyzer to monitor emissions from gas turbine engines and large gas-fired reciprocating engines has previously been reported. In these applications, the CEMcat analyzer demonstrated its capability to meet 40CFR60 relative accuracy requirements. This sensor based analyzer has recently been applied in boiler applications.

  14. Perspective on Catalytic Hydrodeoxygenation of Biomass Pyrolysis Oils: Essential Roles of Fe-based Catalysts

    Energy Technology Data Exchange (ETDEWEB)

    Hong, Yongchun; Hensley, Alyssa; McEwen, Jean-Sabin; Wang, Yong

    2016-06-27

    Catalytic fast pyrolysis is the most promising approach for biofuel production, due to its simple process and versatility to handle lignocellulosic biomass feedstocks with varying and complex compositions. Compared with in situ catalytic fast pyrolysis, ex situ catalytic pyrolysis has the flexibility of optimizing the pyrolysis step and catalytic process individually to improve the quality of pyrolysis oil (stability, oxygen content, acid number, etc.) and to maximize the carbon efficiency in the conversion of biomass to pyrolysis oil. Hydrodeoxygenation is one of the key catalytic functions in ex situ catalytic fast pyrolysis. Recently, Fe-based catalysts have been reported to exhibit superior catalytic properties in hydrodeoxygenation of model compounds in pyrolysis oil, which potentially makes the ex situ pyrolysis of biomass commercially viable due to the abundance and low cost of Fe. Here, we briefly summarize the recent progress on Fe-based catalysts for hydrodeoxygenation of biomass, and provide perspectives on how to further improve Fe-based catalysts (activity and stability) for their potential applications in the emerging area of biomass conversion.

  15. Green technology for conversion of renewable hydrocarbon based on plasma-catalytic approach

    Science.gov (United States)

    Fedirchyk, Igor; Nedybaliuk, Oleg; Chernyak, Valeriy; Demchina, Valentina

    2016-09-01

    The ability to convert renewable biomass into fuels and chemicals is one of the most important steps on our path to green technology and sustainable development. However, the complex composition of biomass poses a major problem for established conversion technologies. The high temperature of thermochemical biomass conversion often leads to the appearance of undesirable byproducts and waste. The catalytic conversion has reduced yield and feedstock range. Plasma-catalytic reforming technology opens a new path for biomass conversion by replacing feedstock-specific catalysts with free radicals generated in the plasma. We studied the plasma-catalytic conversion of several renewable hydrocarbons using the air plasma created by rotating gliding discharge. We found that plasma-catalytic hydrocarbon conversion can be conducted at significantly lower temperatures (500 K) than during the thermochemical ( 1000 K) and catalytic (800 K) conversion. By using gas chromatography, we determined conversion products and found that conversion efficiency of plasma-catalytic conversion reaches over 85%. We used obtained data to determine the energy yield of hydrogen in case of plasma-catalytic reforming of ethanol and compared it with other plasma-based hydrogen-generating systems.

  16. Cobaloxime-based photo-catalytic devices for hydrogen production

    Energy Technology Data Exchange (ETDEWEB)

    Fihri, A.; Artero, V.; Razavet, M.; Baffert, C.; Fontecave, M. [CEA Grenoble, DSV, iRTSV, Lab Chim et Biol Metaux, CNRS, UMR 5249, Univ Grenoble 1, F-38054 Grenoble 9 (France); Leibl, W. [CEA, DSV, iBiTecS, Lab Photocatalyse et Biohydrogene, CNRS, URA 2096, Gif Sur Yvette (France)

    2008-07-01

    In this paper is described the synthesis and activity of a series of novel hetero-dinuclear ruthenium-cobaloxime photo-catalysts able to achieve the photochemical production of hydrogen with the highest turnover numbers so far reported for such devices. First of all, substituting cobalt for rare and expensive platinum, palladium, or rhodium metals in photo-catalysts is a first step toward economically viable hydrogen production. Cobaloximes appear to be good candidates for H{sub 2}-evolving catalysts, and they may provide a good basis for the design of photo-catalysts that function in pure water as both the solvent and the sustainable proton source. Secondly, a molecular connection between the sensitizer and the H{sub 2}-evolving catalyst seems to provide advantages regarding the photo-catalytic activity. Structural modifications of this connection should allow a better tuning of the electron transfer between the light-harvesting unit and the catalytic center and thus an increase of the efficiency of the system. (O.M.)

  17. 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.

  18. Alkali resistivity of Cu based selective catalytic reduction catalysts

    DEFF Research Database (Denmark)

    Putluru, Siva Sankar Reddy; Jensen, Anker Degn; Riisager, Anders;

    2012-01-01

    The deactivation of V2O5–WO3–TiO2, Cu–HZSM5 and Cu–HMOR plate type monolithic catalysts was investigated when exposed to KCl aerosols in a bench-scale reactor. Fresh and exposed catalysts were characterized by selective catalytic reduction (SCR) activity measurements, scanning electron microscope...... catalysts revealed that the potassium salt not only deposited on the catalyst surface, but also penetrated into the catalyst wall. Thus, the K/M ratio (M = V or Cu) was high on V2O5–WO3–TiO2 catalyst and comparatively less on Cu–HZSM5 and Cu–HMOR catalysts. NH3-TPD revealed that the KCl exposed Cu–HZSM5...

  19. Catalytic flash pyrolysis of oil-impregnated-wood and jatropha cake using sodium based catalysts

    KAUST Repository

    Imran, Ali

    2015-11-24

    Catalytic pyrolysis of wood with impregnated vegetable oil was investigated and compared with catalytic pyrolysis of jatropha cake making use of sodium based catalysts to produce a high quality bio-oil. The catalytic pyrolysis was carried out in two modes: in-situ catalytic pyrolysis and post treatment of the pyrolysis vapors. The in-situ catalytic pyrolysis was carried out in an entrained flow reactor system using a premixed feedstock of Na2CO3 and biomass and post treatment of biomass pyrolysis vapor was conducted in a downstream fixed bed reactor of Na2CO3/γ-Al2O3. Results have shown that both Na2CO3 and Na2CO3/γ-Al2O3 can be used for the production of a high quality bio-oil from catalytic pyrolysis of oil-impregnated-wood and jatropha cake. The catalytic bio-oil had very low oxygen content, water content as low as 1wt.%, a neutral pH, and a high calorific value upto 41.8MJ/kg. The bio-oil consisted of high value chemical compounds mainly hydrocarbons and undesired compounds in the bio-oil were either completely removed or considerably reduced. Increasing the triglycerides content (vegetable oil) in the wood enhanced the formation of hydrocarbons in the bio-oil. Post treatment of the pyrolysis vapor over a fixed bed of Na2CO3/γ-Al2O3 produced superior quality bio-oil compared to in-situ catalytic pyrolysis with Na2CO3. This high quality bio-oil may be used as a precursor in a fractionating process for the production of alternative fuels. © 2015 Elsevier B.V.

  20. Catalytic thermal treatment (catalytic thermolysis) of a rice grain-based biodigester effluent of an alcohol distillery plant.

    Science.gov (United States)

    Prajapati, Abhinesh Kumar; Chaudhari, Parmesh Kumar; Mazumdar, Bidyut; Choudhary, Rumi

    2015-01-01

    The catalytic thermolysis (CT) process is an effective and novel approach to treat rice grain-based biodigester effluent (BDE) of the distillery plant. CT treatment of rice grain-based distillery wastewater was carried out in a 0.5 dm(3) thermolytic batch reactor using different catalysts such as CuO, copper sulphate and ferrous sulphate. With the CuO catalyst, a temperature of 95°C, catalyst loading of 4 g/dm(3) and pH 5 were found to be optimal, obtaining a maximum chemical oxygen demand (COD) and colour removal of 80.4% and 72%, respectively. The initial pH (pHi) was an important parameter to remove COD and colour from BDE. At higher pHi (pH 9.5), less COD and colour reduction were observed. The settling characteristics of CT-treated sludge were also analysed at different temperatures. It was noted that the treated slurry at a temperature of 80°C gave best settling characteristics. Characteristics of residues are also analysed at different pH.

  1. Catalytic Kinetics of the Schiff Base Metal Complexes Bearing Side Chain of Cyclic morpholine in Carboxylic Ester Hydrolysis

    Institute of Scientific and Technical Information of China (English)

    ZHANG,Shu-Lin; LI,Min-Jiao; OU,Zhong-Wen; CHEN,Guo-Xu; LIU,Fu-An; XIE,Jia-Qing

    2007-01-01

    It has been reported that two Schiff base transition metal complexes bearing the side chain of the morpholine ring were synthesized and characterized, and two complexes with the same base agent but different metal ions were used as a simulant hydrolase in the catalytic hydrolysis of p-nitrophenyl picolinate in this paper. The mechanism of PNPP catalytic hydrolysis is proposed and supported by the results of the spectral analysis and the kinetic calculation. A kinetic mathematical model, applied to the calculation of the kinetic and thermodynamics parameters of PNPP catalytic hydrolysis, has been established on the foundation of the mechanism proposed. The result of the study shows that the two complexes have a good catalytic activity in PNPP catalytic hydrolysis, and the rate of the PNPP catalytic hydrolysis was increased with the increase of the pH values in the buffer solution and affected by the polarization effect of metal ion of the complexes.

  2. E1DS: catalytic site prediction based on 1D signatures of concurrent conservation.

    Science.gov (United States)

    Chien, Ting-Ying; Chang, Darby Tien-Hao; Chen, Chien-Yu; Weng, Yi-Zhong; Hsu, Chen-Ming

    2008-07-01

    Large-scale automatic annotation of protein sequences remains challenging in postgenomics era. E1DS is designed for annotating enzyme sequences based on a repository of 1D signatures. The employed sequence signatures are derived using a novel pattern mining approach that discovers long motifs consisted of several sequential blocks (conserved segments). Each of the sequential blocks is considerably conserved among the protein members of an EC group. Moreover, a signature includes at least three sequential blocks that are concurrently conserved, i.e. frequently observed together in sequences. In other words, a sequence signature is consisted of residues from multiple regions of the protein sequence, which echoes the observation that an enzyme catalytic site is usually constituted of residues that are largely separated in the sequence. E1DS currently contains 5421 sequence signatures that in total cover 932 4-digital EC numbers. E1DS is evaluated based on a collection of enzymes with catalytic sites annotated in Catalytic Site Atlas. When compared to the famous pattern database PROSITE, predictions based on E1DS signatures are considered more sensitive in identifying catalytic sites and the involved residues. E1DS is available at http://e1ds.ee.ncku.edu.tw/ and a mirror site can be found at http://e1ds.csbb.ntu.edu.tw/.

  3. Fundamentals and Catalytic Applications of CeO2-Based Materials.

    Science.gov (United States)

    Montini, Tiziano; Melchionna, Michele; Monai, Matteo; Fornasiero, Paolo

    2016-05-25

    Cerium dioxide (CeO2, ceria) is becoming an ubiquitous constituent in catalytic systems for a variety of applications. 2016 sees the 40(th) anniversary since ceria was first employed by Ford Motor Company as an oxygen storage component in car converters, to become in the years since its inception an irreplaceable component in three-way catalysts (TWCs). Apart from this well-established use, ceria is looming as a catalyst component for a wide range of catalytic applications. For some of these, such as fuel cells, CeO2-based materials have almost reached the market stage, while for some other catalytic reactions, such as reforming processes, photocatalysis, water-gas shift reaction, thermochemical water splitting, and organic reactions, ceria is emerging as a unique material, holding great promise for future market breakthroughs. While much knowledge about the fundamental characteristics of CeO2-based materials has already been acquired, new characterization techniques and powerful theoretical methods are deepening our understanding of these materials, helping us to predict their behavior and application potential. This review has a wide view on all those aspects related to ceria which promise to produce an important impact on our life, encompassing fundamental knowledge of CeO2 and its properties, characterization toolbox, emerging features, theoretical studies, and all the catalytic applications, organized by their degree of establishment on the market.

  4. Position-based quantum cryptography and catalytic computation

    NARCIS (Netherlands)

    Speelman, F.

    2016-01-01

    In this thesis, we present several results along two different lines of research. The first part concerns the study of position-based quantum cryptography, a topic in quantum cryptography. By combining quantum mechanics with special relativity theory, new cryptographic tasks can be developed that us

  5. Autonomous micromotor based on catalytically pneumatic behavior of balloon-like MnO(x)-graphene crumples.

    Science.gov (United States)

    Chen, Xueli; Wu, Guan; Lan, Tian; Chen, Wei

    2014-07-11

    A novel autonomous micromotor, based on catalytically pneumatic behaviour of balloon-like MnOx-graphene crumples, has been synthesized via an ultrasonic spray pyrolysis method. Through catalytic decomposition of H2O2 into O2, the gas accumulated in a confined space and was released to generate a strong force to push the micromotor.

  6. A new surface catalytic model for silica-based thermal protection material for hypersonic vehicles

    Directory of Open Access Journals (Sweden)

    Li Kai

    2015-10-01

    Full Text Available Silica-based materials are widely employed in the thermal protection system for hypersonic vehicles, and the investigation of their catalytic characteristics is crucially important for accurate aerothermal heating prediction. By analyzing the disadvantages of Norman’s high and low temperature models, this paper combines the two models and proposes an eight-reaction combined surface catalytic model to describe the catalysis between oxygen and silica surface. Given proper evaluation of the parameters according to many references, the recombination coefficient obtained shows good agreement with experimental data. The catalytic mechanisms between oxygen and silica surface are then analyzed. Results show that with the increase of the wall temperature, the dominant reaction contributing to catalytic coefficient varies from Langmuir–Hinshelwood (LH recombination (TW  1350 K. The surface coverage of chemisorption areas varies evidently with the dominant reactions in the high temperature (HT range, while the surface coverage of physisorption areas varies within quite low temperature (LT range (TW < 250 K. Recommended evaluation of partial parameters is also given.

  7. Aged nano-structured platinum based catalyst: effect of chemical treatment on adsorption and catalytic activity.

    Science.gov (United States)

    Shim, Wang Geun; Nahm, Seung Won; Park, Hyuk Ryeol; Yun, Hyung Sun; Seo, Seong Gyu; Kim, Sang Chai

    2011-02-01

    To examine the effect of chemical treatment on the adsorption and catalytic activity of nanostructured platinum based catalyst, the aged commercial Pt/AC catalyst was pretreated with sulfuric acid (H2SO4) and a cleaning agent (Hexane). Several reliable methods such as nitrogen adsorption, X-ray powder diffraction (XRD), scanning electron microscopy (SEM) and inductively coupled plasma (ICP) were employed to characterize the aged Pt/AC catalyst and its chemically pretreated Pt/AC catalysts. The catalytic and adsorption activities of nano-structured heterogeneous Pt/AC catalyst were investigated on the basis of toluene oxidation and adsorption isotherm data. In addition, the adsorption isotherms of toluene were used to calculate the adsorption energy distribution functions for the parent catalyst and its pre-treated nano-structured Pt/AC catalysts. It was found that sulfuric acid aqueous treatment can enhance the catalytic performance of aged Pt/AC catalyst toward catalytic oxidation of toluene. It was also shown that a comparative analysis of the energy distribution functions for nano-structured Pt/AC catalysts as well as the pore size distribution provides valuable information about their structural and energetic heterogeneity.

  8. Molecular basis of the general base catalysis of an α/β-hydrolase catalytic triad.

    Science.gov (United States)

    Sun, Yueru; Yin, Shuhui; Feng, Yitao; Li, Jie; Zhou, Jiahai; Liu, Changdong; Zhu, Guang; Guo, Zhihong

    2014-05-30

    The serine-histidine-aspartate triad is well known for its covalent, nucleophilic catalysis in a diverse array of enzymatic transformations. Here we show that its nucleophilicity is shielded and its catalytic role is limited to being a specific general base by an open-closed conformational change in the catalysis of (1R,6R)-2-succinyl-6-hydroxy-2,4-cyclohexadiene-1-carboxylate synthase (or MenH), a typical α/β-hydrolase fold enzyme in the vitamin K biosynthetic pathway. This enzyme is found to adopt an open conformation without a functional triad in its ligand-free form and a closed conformation with a fully functional catalytic triad in the presence of its reaction product. The open-to-closed conformational transition involves movement of half of the α-helical cap domain, which causes extensive structural changes in the α/β-domain and forces the side chain of the triad histidine to adopt an energetically disfavored gauche conformation to form the functional triad. NMR analysis shows that the inactive open conformation without a triad prevails in ligand-free solution and is converted to the closed conformation with a properly formed triad by the reaction product. Mutation of the residues crucial to this open-closed transition either greatly decreases or completely eliminates the enzyme activity, supporting an important catalytic role for the structural change. These findings suggest that the open-closed conformational change tightly couples formation of the catalytic triad to substrate binding to enhance the substrate specificities and simultaneously shield the nucleophilicity of the triad, thus allowing it to expand its catalytic power beyond the nucleophilic catalysis.

  9. Cross-catalytic peptide nucleic acid (PNA) replication based on templated ligation

    DEFF Research Database (Denmark)

    Singhal, Abhishek; Nielsen, Peter E

    2014-01-01

    We report the first PNA self-replicating system based on template directed cross-catalytic ligation, a process analogous to biological replication. Using two template PNAs and four pentameric precursor PNAs, all four possible carbodiimide assisted amide ligation products were detected and identif...... oligonucleotides are feasible, thereby strengthening the foundation for the discussion of a possible role for PNA (like) genetic material in the prebiotic evolution of life and lay the ground for further studies into evolution of such potentially prebiotic systems....

  10. Glycerol-based carbon materials for the catalytic wet peroxide oxidation process

    OpenAIRE

    Ribeiro, Rui S.; Silva, Adrián; Pinho, Maria; Figueiredo,José; Faria, Joaquim; Gomes, Helder

    2013-01-01

    It is known that metal-free carbon materials can act as catalysts for the catalytic wet peroxide oxidation (CWPO) process to treat organic pollutants in aqueous solutions [I]. On the other hand, crude glycerol, such as resulting from biodiesel production, is being offered as an abundant and low cost feedstock [2]. In the present work, glycerol-based carbon materials (OBCMs) with distinct properties were produced and tested as catalysts for CWPO, using 2-nitrophenol (2-NP) as a ...

  11. A novel liquid organic hydrogen carrier system based on catalytic peptide formation and hydrogenation.

    Science.gov (United States)

    Hu, Peng; Fogler, Eran; Diskin-Posner, Yael; Iron, Mark A; Milstein, David

    2015-04-17

    Hydrogen is an efficient green fuel, but its low energy density when stored under high pressure or cryogenically, and safety issues, presents significant disadvantages; hence finding efficient and safe hydrogen carriers is a major challenge. Of special interest are liquid organic hydrogen carriers (LOHCs), which can be readily loaded and unloaded with considerable amounts of hydrogen. However, disadvantages include high hydrogen pressure requirements, high reaction temperatures for both hydrogenation and dehydrogenation steps, which require different catalysts, and high LOHC cost. Here we present a readily reversible LOHC system based on catalytic peptide formation and hydrogenation, using an inexpensive, safe and abundant organic compound with high potential capacity to store and release hydrogen, applying the same catalyst for loading and unloading hydrogen under relatively mild conditions. Mechanistic insight of the catalytic reaction is provided. We believe that these findings may lead to the development of an inexpensive, safe and clean liquid hydrogen carrier system.

  12. Removal of dissolved oxygen from water using a Pd-resin based catalytic reactor

    Institute of Scientific and Technical Information of China (English)

    Wenxin SHI; Chongwei CUI; Liye ZHAO; Shuili YU; Xia YUN

    2009-01-01

    The removal of dissolved oxygen (DO) from water was studied experimentally in a Pd-resin base catalyst reactor using purified hydrogen gas as a reducing agent. The effects of various operating conditions, such as hydrogen and water flow rates, height of the catalytic resin bed, temperature, pH value and nan time, on the removal of DO, had been studied extensively. The results shows that DO could be removed by the reactor from ppm to ppb levels at ambient temperature. Increases of temperature, H2gas rate and the height of the catalytic resin were helpful to improve the DO removal rate. The change of pH value fom 4 to 12 resulted in no effect on DO removal. Reaction time was the key factor to control the DO removal efficiency. Only when the reaction time was longer than 2.3 minutes under the experimental conditions, could a very low DO level be achieved.

  13. Transient and sustained elementary flux mode networks on a catalytic string-based chemical evolution model.

    Science.gov (United States)

    Pereira, José A

    2014-08-01

    Theoretical models designed to test the metabolism-first hypothesis for prebiotic evolution have yield strong indications about the hypothesis validity but could sometimes use a more extensive identification between model objects and real objects towards a more meaningful interpretation of results. In an attempt to go in that direction, the string-based model SSE ("steady state evolution") was developed, where abstract molecules (strings) and catalytic interaction rules are based on some of the most important features of carbon compounds in biological chemistry. The system is open with a random inflow and outflow of strings but also with a permanent string food source. Although specific catalysis is a key aspect of the model, used to define reaction rules, the focus is on energetics rather than kinetics. Standard energy change tables were constructed and used with standard formation reactions to track energy flows through the interpretation of equilibrium constant values. Detection of metabolic networks on the reaction system was done with elementary flux mode (EFM) analysis. The combination of these model design and analysis options enabled obtaining metabolic and catalytic networks showing several central features of biological metabolism, some more clearly than in previous models: metabolic networks with stepwise synthesis, energy coupling, catalysts regulation, SN2 coupling, redox coupling, intermediate cycling, coupled inverse pathways (metabolic cycling), autocatalytic cycles and catalytic cascades. The results strongly suggest that the main biological metabolism features, including the genotype-phenotype interpretation, are caused by the principles of catalytic systems and are prior to modern genetic systems principles. It also gives further theoretical support to the thesis that the basic features of biologic metabolism are a consequence of the time evolution of a random catalyst search working on an open system with a permanent food source. The importance

  14. Low temperature catalytic combustion of propane over Pt-based catalyst with inverse opal microstructure in a microchannel reactor.

    Science.gov (United States)

    Guan, Guoqing; Zapf, Ralf; Kolb, Gunther; Men, Yong; Hessel, Volker; Loewe, Holger; Ye, Jianhui; Zentel, Rudolf

    2007-01-21

    A novel Pt-based catalyst with highly regular, periodic inverse opal microstructure was fabricated in a microchannel reactor, and catalytic testing revealed excellent conversion and stable activity for propane combustion at low temperatures.

  15. Catalytic Spectrophotometry for Vanadium Determination Based on Oxidation of Arsenazo Ⅲ by Bichromate

    Institute of Scientific and Technical Information of China (English)

    1999-01-01

    A catalytic spectrophotometry for the determination of trace amount of vanadium was developed based on its catalytic effect on the oxidation of arsenazo Ⅲ by potassium bichromate in weak acidic medium. The optimized conditions for determinations are: cK2Cr2O7=3.0×10-5 mol·L-1, carsenazo Ⅲ=3.0×10-5 mol·L-1, pH=4.0, t=90℃. The calibration graph is linear for 0.02~0.2 μg·ml-1, and the detection limit is 0.02 μg·ml-1 V. The apparent active energy of this catalytic reaction is 21.72 kJ·mol-1. Most foreign ions do not interfere with the determination of vadadium, except for Fe(Ⅱ) and Co(Ⅱ), and their interferences could be eliminated by ion exchange. The present method has been used to make the determination of vanadium in human hair, tea, potato and wastewater, and the results were satisfactory.

  16. Catalytic wet air oxidation of 2-chlorophenol over sewage sludge-derived carbon-based catalysts

    Energy Technology Data Exchange (ETDEWEB)

    Tu, Yuting [Institut de recherches sur la catalyse et l’environnement de Lyon (IRCELYON), CNRS – Université Claude Bernard Lyon 1, 2 Avenue Albert Einstein, 69626 Villeurbanne Cedex (France); School of Environmental Science and Engineering, Sun Yat-Sen University, Guangzhou 510275 (China); Xiong, Ya; Tian, Shuanghong [School of Environmental Science and Engineering, Sun Yat-Sen University, Guangzhou 510275 (China); Guangdong Provincial Key Laboratory of Environmental Pollution Control and Remediation Technology, Guangzhou 510275 (China); Kong, Lingjun [School of Environmental Science and Engineering, Sun Yat-Sen University, Guangzhou 510275 (China); Descorme, Claude, E-mail: claude.descorme@ircelyon.univ-lyon1.fr [Institut de recherches sur la catalyse et l’environnement de Lyon (IRCELYON), CNRS – Université Claude Bernard Lyon 1, 2 Avenue Albert Einstein, 69626 Villeurbanne Cedex (France)

    2014-07-15

    Highlights: • A sewage sludge derived carbon-supported iron oxide catalyst (FeSC) was prepared. • FeSC exhibited high catalytic activity in the wet air oxidation of 2-chlorophenol. • A strong correlation was observed between the 2-CP conversion, the iron leaching and the pH. • Using an acetate buffer, the iron leaching was suppressed while keeping some catalytic activity. • A simplified reaction pathway was proposed for the CWAO of 2-CP over the FeSC catalyst. - Abstract: A sewage sludge derived carbon-supported iron oxide catalyst (FeSC) was prepared and used in the Catalytic Wet Air Oxidation (CWAO) of 2-chlorophenol (2-CP). The catalysts were characterized in terms of elemental composition, surface area, pH{sub PZC}, XRD and SEM. The performances of the FeSC catalyst in the CWAO of 2-CP was assessed in a batch reactor operated at 120 °C under 0.9 MPa oxygen partial pressure. Complete decomposition of 2-CP was achieved within 5 h and 90% Total Organic Carbon (TOC) was removed after 24 h of reaction. Quite a straight correlation was observed between the 2-CP conversion, the amount of iron leached in solution and the pH of the reaction mixture at a given reaction time, indicating a strong predominance of the homogeneous catalysis contribution. The iron leaching could be efficiently prevented when the pH of the solution was maintained at values higher than 4.5, while the catalytic activity was only slightly reduced. Upon four successive batch CWAO experiments, using the same FeSC catalyst recovered by filtration after pH adjustment, only a very minor catalyst deactivation was observed. Finally, based on all the identified intermediates, a simplified reaction pathway was proposed for the CWAO of 2-CP over the FeSC catalyst.

  17. A simple red-ox titrimetric method for the evaluation of photo-catalytic activity of titania based catalysts

    Indian Academy of Sciences (India)

    Y S Satpute; S A Borkar; S R Dharwadkar

    2003-12-01

    A simple red-ox titrimetry method has been developed for rapid evaluation of the photo catalytic activity of TiO2 based photo-catalysts. The analytical procedure employs monitoring the kinetics of a simple one electron transfer reduction reaction of conversion of Ce4+ to Ce3+ in dilute aqueous solution in presence of sunlight. The photo-catalytic activity of TiO2 synthesized by two different routes was evaluated by the above technique. The effect of surface area, crystallite size and polymorphic contents on the photo-catalytic activity of TiO2 was also studied employing this method.

  18. Determination of iron and aluminum based on the catalytic effect on the reaction of xylene cyanol FF with hydrogen peroxide and potassium periodate

    OpenAIRE

    Cai, Longfei; Xu, Chunxiu

    2011-01-01

    A simple, sensitive and selective method for the simultaneous determination of trace iron and aluminum by catalytic spectrophotometry is presented. This method is based on the catalytic effects of iron and aluminum on the reaction of xylene cyanol FF with hydrogen peroxide and potassium periodate. Both iron and aluminum did not show catalytic effects on the oxidation reaction of xylene cyanol FF in the presence of either hydrogen peroxide or potassium periodate. However, significant catalytic...

  19. Preparation of ultrafine Ce-based oxide nanoparticles and their catalytic performances for diesel soot combustion

    Institute of Scientific and Technical Information of China (English)

    韦岳长; 赵震; 焦金庆; 刘坚; 段爱军; 姜桂元

    2014-01-01

    The ultrafine Ce-based oxide nanoparticles with different element dopings (Zr, Y) were synthesized by the method of mi-cropores-diffused coprecipitation (MDC) using ammonia solution as the precipitation agent. The activities of the catalysts for soot oxidation were evaluated by the temperature-programmed oxidation (TPO) reaction. Ce-based oxides prepared in this study exhibited high catalytic activity for soot oxidation under the condition of loose contact between soot particles and catalysts, and the catalytic ac-tivity of ultrafine Ce0.9Zr0.1O2 nanoparticle for soot combustion was the highest, whose T10, T50 and SCO2m was 364, 442 ºC and 98.3%, respectively. All catalysts were systematically characterized by means of X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), Brumauer-Emett-Teller (BET), Fourier transform infrared spectroscopy (FT-IR) and UV-Vis diffuse reflectance spectroscopy (UV-Vis DRS). It was indicated that the MDC method could prepare the ultrafine Ce-based oxide nanoparticles whose the crystal lattice were perfect, and the BET surface area and average crystal size of the ultrafine nanoparticles changed with the different element dopings (Zr, Y). The H2-TPR measurements showed that the ultrafine Ce-based ox-ide nanoparticles with the doping-Zr cation could be favorable for improving the redox property of the catalysts.

  20. MTO Schiff-base complexes: synthesis, structures and catalytic applications in olefin epoxidation.

    Science.gov (United States)

    Zhou, Ming-Dong; Zhao, Jin; Li, Jun; Yue, Shuang; Bao, Chang-Nian; Mink, Janos; Zang, Shu-Liang; Kühn, Fritz E

    2007-01-01

    Several Schiff-base ligands readily form complexes with methyltrioxorhenium(VII) (MTO) by undergoing a hydrogen transfer from a ligand-bound OH group to a ligand N atom. The resulting complexes are stable at room temperature and can be handled and stored in air without problems. Due to the steric demands of the ligands they display distorted trigonal-bipyramidal structures in the solid state, as shown by X-ray crystallography, with the O(-) moiety binding to the Lewis acidic Re atom and the Re-bound methyl group being located either in cis or trans position to the Schiff base. In solution, however, the steric differences seem not to be maintained, as can be deduced from (17)O NMR spectroscopy. Furthermore, the Schiff-base ligands exchange with donor ligands. Nevertheless, the catalytic behaviour is influenced significantly by the Schiff bases coordinated to the MTO moiety, which lead either to high selectivities and good activities or to catalyst decomposition. A large excess of ligand, in contrast to the observations with aromatic N-donor ligands, is detrimental to the catalytic performance as it leads to catalyst decomposition.

  1. Aligned carbon nanotubes catalytically grown on iron-based nanoparticles obtained by laser-induced CVD

    OpenAIRE

    Le Normand, Francois; Cojocaru, Costel Sorin; Ersen, Ovidiu; Legagneux, Pierre; Gangloff, Laurent; Fleaca, C.; Alexandrescu, Rodica; Dumitrache, Florin; Morjan, Ion

    2007-01-01

    International audience; Iron-based nanoparticles are prepared by a laser-induced chemical vapor deposition (CVD) process. They are characterized as body-centered Fe and Fe2O3 (maghemite/magnetite) particles with sizes ::;5 and 10 nm, respectively. The Fe particles are embedded in a protective carbon matrix. Both kind of particles are dispersed by spin-coating on SiO2/Si(1 0 0) flat substrates. They are used as catalyst to grow carbon nanotubes by a plasma- and filaments-assisted catalytic CVD...

  2. New URJC-1 Material with Remarkable Stability and Acid-Base Catalytic Properties

    Directory of Open Access Journals (Sweden)

    Pedro Leo

    2016-02-01

    Full Text Available Emerging new metal-organic structures with tunable physicochemical properties is an exciting research field for diverse applications. In this work, a novel metal-organic framework Cu(HIT(DMF0.5, named URJC-1, with a three-dimensional non-interpenetrated utp topological network, has been synthesized. This material exhibits a microporous structure with unsaturated copper centers and imidazole–tetrazole linkages that provide accessible Lewis acid/base sites. These features make URJC-1 an exceptional candidate for catalytic application in acid and base reactions of interest in fine chemistry. The URJC-1 material also displays a noteworthy thermal and chemical stability in different organic solvents of different polarity and boiling water. Its catalytic activity was evaluated in acid-catalyzed Friedel–Crafts acylation of anisole with acetyl chloride and base-catalyzed Knoevenagel condensation of benzaldehyde with malononitrile. In both cases, URJC-1 material showed very good performance, better than other metal organic frameworks and conventional catalysts. In addition, a remarkable structural stability was proven after several consecutive reaction cycles.

  3. Critical review of Pd-based catalytic treatment of priority contaminants in water.

    Science.gov (United States)

    Chaplin, Brian P; Reinhard, Martin; Schneider, William F; Schüth, Christoph; Shapley, John R; Strathmann, Timothy J; Werth, Charles J

    2012-04-03

    Catalytic reduction of water contaminants using palladium (Pd)-based catalysts and hydrogen gas as a reductant has been extensively studied at the bench-scale, but due to technical challenges it has only been limitedly applied at the field-scale. To motivate research that can overcome these technical challenges, this review critically analyzes the published research in the area of Pd-based catalytic reduction of priority drinking water contaminants (i.e., halogenated organics, oxyanions, and nitrosamines), and identifies key research areas that should be addressed. Specifically, the review summarizes the state of knowledge related to (1) proposed reaction pathways for important classes of contaminants, (2) rates of contaminant reduction with different catalyst formulations, (3) long-term sustainability of catalyst activity with respect to natural water foulants and regeneration strategies, and (4) technology applications. Critical barriers hindering implementation of the technology are related to catalyst activity (for some contaminants), stability, fouling, and regeneration. New developments overcoming these limitations will be needed for more extensive field-scale application of this technology.

  4. A biophysically based mathematical model for the catalytic mechanism of glutathione reductase.

    Science.gov (United States)

    Pannala, Venkat R; Bazil, Jason N; Camara, Amadou K S; Dash, Ranjan K

    2013-12-01

    Glutathione reductase (GR) catalyzes the reduction of oxidized glutathione (GSSG) to reduced glutathione (GSH) using NADPH as the reducing cofactor, and thereby maintains a constant GSH level in the system. GSH scavenges superoxide (O2(*-)) and hydroxyl radicals (OH) nonenzymatically or by serving as an electron donor to several enzymes involved in reactive oxygen species (ROS) detoxification. In either case, GSH oxidizes to GSSG and is subsequently regenerated by the catalytic action of GR. Although the GR kinetic mechanism has been extensively studied under various experimental conditions with variable substrates and products, the catalytic mechanism has not been studied in terms of a mechanistic model that accounts for the effects of the substrates and products on the reaction kinetics. The aim of this study is therefore to develop a comprehensive mathematical model for the catalytic mechanism of GR. We use available experimental data on GR kinetics from various species/sources to develop the mathematical model and estimate the associated model parameters. The model simulations are consistent with the experimental observation that GR operates via both ping-pong and sequential branching mechanisms based on relevant concentrations of its reaction substrate GSSG. Furthermore, we show the observed pH-dependent substrate inhibition of GR activity by GSSG and bimodal behavior of GR activity with pH. The model presents a unique opportunity to understand the effects of products on the kinetics of GR. The model simulations show that under physiological conditions, where both substrates and products are present, the flux distribution depends on the concentrations of both GSSG and NADP(+), with ping-pong flux operating at low levels and sequential flux dominating at higher levels. The kinetic model of GR may serve as a key module for the development of integrated models for ROS-scavenging systems to understand protection of cells under normal and oxidative stress

  5. Preparation and Catalytic Properties of Polymer-Bound Schiff Base Ternary Complexes

    Institute of Scientific and Technical Information of China (English)

    HAO Cheng-jun; WANG Rong-min; HE Yu-feng; WANG Yun-pu; XIA Chun-gu

    2004-01-01

    The polymer-bound Schiff base ternary manganese complexes [PS-SalPhe-Mn-L (L = Phen, Bipy and 8HQ)-] have been prepared from the polymer-bound Schiff base ligand, a manganese salt and the second ligand, such as 1,10-phenanthroline(phen), 2,2′-bipyridyl(bipy) and 8-quinolinol(8HQ). The polymer-bound Schiff base ternary manganese complexes were characterized by means of infrared spectrometry and ICPAES. The catalytic activities of the complexes have been studied in the aerobic epoxidation of long-chain linear a[iphatic olefins. It is shown that 1-octene or 1-decene can be directly oxidized by molecular oxygen when catalyzed by PS-SalPhe-Mn-L(L=Phen, Bipy and 8HQ), and 1,2-epoxy alkane can be afforded in these reactions.

  6. Emergence of the First Catalytic Oligonucleotides in a Formamide-Based Origin Scenario.

    Science.gov (United States)

    Šponer, Judit E; Šponer, Jiří; Nováková, Olga; Brabec, Viktor; Šedo, Ondrej; Zdráhal, Zbyněk; Costanzo, Giovanna; Pino, Samanta; Saladino, Raffaele; Di Mauro, Ernesto

    2016-03-07

    50 years after the historical Miller-Urey experiment, the formamide-based scenario is perhaps the most powerful concurrent hypothesis for the origin of life on our planet besides the traditional HCN-based concept. The information accumulated during the last 15 years in this topic is astonishingly growing and nowadays the formamide-based model represents one of the most complete and coherent pathways leading from simple prebiotic precursors up to the first catalytically active RNA molecules. In this work, we overview the major events of this long pathway that have emerged from recent experimental and theoretical studies, mainly concentrating on the mechanistic, methodological, and structural aspects of this research.

  7. Catalytic wet air oxidation of 2-chlorophenol over sewage sludge-derived carbon-based catalysts.

    Science.gov (United States)

    Tu, Yuting; Xiong, Ya; Tian, Shuanghong; Kong, Lingjun; Descorme, Claude

    2014-07-15

    A sewage sludge derived carbon-supported iron oxide catalyst (FeSC) was prepared and used in the Catalytic Wet Air Oxidation (CWAO) of 2-chlorophenol (2-CP). The catalysts were characterized in terms of elemental composition, surface area, pHPZC, XRD and SEM. The performances of the FeSC catalyst in the CWAO of 2-CP was assessed in a batch reactor operated at 120°C under 0.9MPa oxygen partial pressure. Complete decomposition of 2-CP was achieved within 5h and 90% Total Organic Carbon (TOC) was removed after 24h of reaction. Quite a straight correlation was observed between the 2-CP conversion, the amount of iron leached in solution and the pH of the reaction mixture at a given reaction time, indicating a strong predominance of the homogeneous catalysis contribution. The iron leaching could be efficiently prevented when the pH of the solution was maintained at values higher than 4.5, while the catalytic activity was only slightly reduced. Upon four successive batch CWAO experiments, using the same FeSC catalyst recovered by filtration after pH adjustment, only a very minor catalyst deactivation was observed. Finally, based on all the identified intermediates, a simplified reaction pathway was proposed for the CWAO of 2-CP over the FeSC catalyst.

  8. Acid-base and catalytic properties of the products of oxidative thermolysis of double complex compounds

    Science.gov (United States)

    Pechenyuk, S. I.; Semushina, Yu. P.; Kuz'mich, L. F.; Ivanov, Yu. V.

    2016-01-01

    Acid-base properties of the products of thermal decomposition of [M(A)6] x; [M1(L)6] y (where M is Co, Cr, Cu, Ni; M1 is Fe, Cr, Co; A is NH3, 1/2 en, 1/2 pn, CO(NH2)2; and L is CN, 1/2C2O4) binary complexes in air and their catalytic properties in the oxidation reaction of ethanol with atmospheric oxygen are studied. It is found that these thermolysis products are mixed oxides of the central atoms of complexes characterized by pH values of the zero charge point in the region of 4-9, OH-group sorption limits from 1 × 10-4 to 4.5 × 10-4 g-eq/g, OH-group surface concentrations of 10-50 nm-2 in 0.1 M NaCl solutions, and S sp from 3 to 95 m2/g. Their catalytic activity is estimated from the apparent rate constant of the conversion of ethanol in CO2. The values of constants are (1-6.5) × 10-5 s-1, depending on the gas flow rate and the S sp value.

  9. Physics-based enzyme design: predicting binding affinity and catalytic activity.

    Science.gov (United States)

    Sirin, Sarah; Pearlman, David A; Sherman, Woody

    2014-12-01

    Computational enzyme design is an emerging field that has yielded promising success stories, but where numerous challenges remain. Accurate methods to rapidly evaluate possible enzyme design variants could provide significant value when combined with experimental efforts by reducing the number of variants needed to be synthesized and speeding the time to reach the desired endpoint of the design. To that end, extending our computational methods to model the fundamental physical-chemical principles that regulate activity in a protocol that is automated and accessible to a broad population of enzyme design researchers is essential. Here, we apply a physics-based implicit solvent MM-GBSA scoring approach to enzyme design and benchmark the computational predictions against experimentally determined activities. Specifically, we evaluate the ability of MM-GBSA to predict changes in affinity for a steroid binder protein, catalytic turnover for a Kemp eliminase, and catalytic activity for α-Gliadin peptidase variants. Using the enzyme design framework developed here, we accurately rank the most experimentally active enzyme variants, suggesting that this approach could provide enrichment of active variants in real-world enzyme design applications.

  10. High performance catalytic distillation using CNTs-based holistic catalyst for production of high quality biodiesel

    Science.gov (United States)

    Zhang, Dongdong; Wei, Dali; Li, Qi; Ge, Xin; Guo, Xuefeng; Xie, Zaiku; Ding, Weiping

    2014-02-01

    For production of biodiesel from bio oils by heterogeneous catalysis, high performance catalysts of transesterification and the further utilization of glycerol have been the two points of research. The process seemed easy, however, has never been well established. Here we report a novel design of catalytic distillation using hierachically integrated CNTs-based holistic catalyst to figure out the two points in one process, which shows high performance both for the conversion of bio oils to biodiesel and, unexpectedly, for the conversion of glycerol to more valuable chemicals at the same time. The method, with integration of nano, meso to macro reactor, has overwhelming advantages over common technologies using liquid acids or bases to catalyze the reactions, which suffer from the high cost of separation and unsolved utilization of glycerol.

  11. Tetrahedral DNA nanostructure-based microRNA biosensor coupled with catalytic recycling of the analyte.

    Science.gov (United States)

    Miao, Peng; Wang, Bidou; Chen, Xifeng; Li, Xiaoxi; Tang, Yuguo

    2015-03-25

    MicroRNAs are not only important regulators of a wide range of cellular processes but are also identified as promising disease biomarkers. Due to the low contents in serum, microRNAs are always difficult to detect accurately . In this study, an electrochemical biosensor for ultrasensitive detection of microRNA based on tetrahedral DNA nanostructure is developed. Four DNA single strands are engineered to form a tetrahedral nanostructure with a pendant stem-loop and modified on a gold electrode surface, which largely enhances the molecular recognition efficiency. Moreover, taking advantage of strand displacement polymerization, catalytic recycling of microRNA, and silver nanoparticle-based solid-state Ag/AgCl reaction, the proposed biosensor exhibits high sensitivity with the limit of detection down to 0.4 fM. This biosensor shows great clinical value and may have practical utility in early diagnosis and prognosis of certain diseases.

  12. Synthesis of novel carbon/silica composites based strong acid catalyst and its catalytic activities for acetalization

    Indian Academy of Sciences (India)

    Yueqing Lu; Xuezheng Liang; Chenze Qi

    2012-06-01

    Novel solid acid based on carbon/silica composites are synthesized through one-pot hydrothermal carbonization of hydroxyethylsulfonic acid, sucrose and tetraethyl orthosilicate (TEOS). The novel solid acid owned the acidity of 2.0 mmol/g, much higher than that of the traditional solid acids such as Nafion and Amberlyst-15 (0.8 mmol/g). The catalytic activities of the solid acid are investigated through acetalization. The results showed that the novel solid acid was very efficient for the reactions. The high acidity and catalytic activities made the novel carbon/silica composites based solid acid hold great potential for the green chemical processes.

  13. Removal of ammonia from aqueous solutions by catalytic oxidation with copper-based rare earth composite metal materials: catalytic performance, characterization, and cytotoxicity evaluation

    Institute of Scientific and Technical Information of China (English)

    Chang-Mao Hung

    2011-01-01

    Ammonia (NH3) has an important use in the chemical industry and is widely found in industrial wastewater.For this investigation of copper-based rare earth composite metal materials,aqueous solutions containing 400 mg/L of ammonia were oxidized in a batch-bed reactor with a catalyst prepared by the co-precipitation of copper nitrate,lanthanum nitrate and cerium nitrate.Barely any of the dissolved ammonia was removed by wet oxidation without a catalyst,but about 88% of the ammonia was reduced during wet oxidation over the catalysts at 423 K with an oxygen partial pressure of 4.0 MPa.The catalytic redox behavior was determined by cyclic voltammetry (CV).Furthermore,the catalysts were characterized using thermogravimetric analyzer (TGA) and scanning electron microscope-energy dispersive X-ray spectroscopy (SEM-EDX),which showed that the catalytic behavior was related to the metal oxide properties of the catalyst.In addition,the copper-lanthanum-cerium composite-induced cytotoxicity in the human lung MRC-5 cell line was tested,and the percentage cell survival was determined by 3-(4,5-dimethylthiazol-2-yl)-5-(3-carboxymethoxyphenyl)-2-(4-sulfophenyl)-2H-tetra-zolium (MTS) analysis in vitro.No apparent cytotoxicity was observed when the human lung cells were exposed to the copper-lanthanum-cerium composite.

  14. Aligned carbon nanotubes catalytically grown on iron-based nanoparticles obtained by laser-induced CVD

    Energy Technology Data Exchange (ETDEWEB)

    Le Normand, F. [Groupe Surfaces and Interfaces, IPCMS, UMR 7504 CNRS, Bat 70, 23 rue du Loess, 67034 Strasbourg Cedex (France)], E-mail: Francois.Le-Normand@ipcms.u-strasbg.fr; Cojocaru, C.S.; Ersen, O. [Groupe Surfaces and Interfaces, IPCMS, UMR 7504 CNRS, Bat 70, 23 rue du Loess, 67034 Strasbourg Cedex (France); Legagneux, P.; Gangloff, L. [THALES R and T, Departementale 128, 91747 Palaiseau Cedex (France); Fleaca, C. [Groupe Surfaces and Interfaces, IPCMS, UMR 7504 CNRS, Bat 70, 23 rue du Loess, 67034 Strasbourg Cedex (France); National Institute for Lasers, Plasma and Radiation Physics, Laser Department, P.O. Box MG-36, R-76900 Bucharest (Romania); Alexandrescu, R.; Dumitrache, F.; Morjan, I. [National Institute for Lasers, Plasma and Radiation Physics, Laser Department, P.O. Box MG-36, R-76900 Bucharest (Romania)

    2007-12-15

    Iron-based nanoparticles are prepared by a laser-induced chemical vapor deposition (CVD) process. They are characterized as body-centered Fe and Fe{sub 2}O{sub 3} (maghemite/magnetite) particles with sizes {<=}5 and 10 nm, respectively. The Fe particles are embedded in a protective carbon matrix. Both kind of particles are dispersed by spin-coating on SiO{sub 2}/Si(1 0 0) flat substrates. They are used as catalyst to grow carbon nanotubes by a plasma- and filaments-assisted catalytic CVD process (PE-HF-CCVD). Vertically oriented and thin carbon nanotubes (CNTs) were grown with few differences between the two samples, except the diameter in relation to the initial size of the iron particles, and the density. The electron field emission of these samples exhibit quite interesting behavior with a low turn-on voltage at around 1 V/{mu}m.

  15. Aligned carbon nanotubes catalytically grown on iron-based nanoparticles obtained by laser-induced CVD

    Science.gov (United States)

    Le Normand, F.; Cojocaru, C. S.; Ersen, O.; Legagneux, P.; Gangloff, L.; Fleaca, C.; Alexandrescu, R.; Dumitrache, F.; Morjan, I.

    2007-12-01

    Iron-based nanoparticles are prepared by a laser-induced chemical vapor deposition (CVD) process. They are characterized as body-centered Fe and Fe 2O 3 (maghemite/magnetite) particles with sizes ≤5 and 10 nm, respectively. The Fe particles are embedded in a protective carbon matrix. Both kind of particles are dispersed by spin-coating on SiO 2/Si(1 0 0) flat substrates. They are used as catalyst to grow carbon nanotubes by a plasma- and filaments-assisted catalytic CVD process (PE-HF-CCVD). Vertically oriented and thin carbon nanotubes (CNTs) were grown with few differences between the two samples, except the diameter in relation to the initial size of the iron particles, and the density. The electron field emission of these samples exhibit quite interesting behavior with a low turn-on voltage at around 1 V/μm.

  16. Electro-catalytic oxidation of phenol with Ti-base lead dioxide electrode

    Institute of Scientific and Technical Information of China (English)

    王东田; 魏杰; 于秀娟; 杨红

    2003-01-01

    The Ti-base PbO2 electrode prepared by electrodeposition of PbO2 on the surface of titanium was used for electro-catalytic oxidation of phenol in waste water. The experimental results show that the electrodeposition of PbO2 at a higher current density for a short time, then followed by a lower current density can get a compact and combinative PbO2 layer. The properties of a Ti/PbO2 electrode with an interlayer of oxide are the best. When this kind of electrode is used to treat phenol containing waste water, the phenol-removal rate is higher and the slot voltage is lower. In addition, by using the phenol-removal rate as an index, the influences of electrolysis current density, mass transfer condition and pH were studied and the optimal condition was confirmed.

  17. Restoration of catalytic activity beyond wild-type level in glucoamylase from Aspergillus awamori by oxidation of the Glu400-->Cys catalytic-base mutant to cysteinesulfinic acid.

    Science.gov (United States)

    Fierobe, H P; Mirgorodskaya, E; McGuire, K A; Roepstorff, P; Svensson, B; Clarke, A J

    1998-03-17

    Glucoamylase catalyzes the hydrolysis of glucosidic bonds with inversion of the anomeric configuration. Site-directed mutagenesis and three-dimensional structure determination of the glucoamylase from Aspergillus awamori previously identified Glu179 and Glu400 as the general acid and base catalyst, respectively. The average distance between the two carboxyl groups was measured to be 9.2 A, which is typical for inverting glycosyl hydrolases. In the present study, this distance was increased by replacing the catalytic base Glu400 with cysteine which was then oxidized to cysteinesulfinic acid. Initially, this oxidation occurred during attempts to carboxyalkylate the Cys400 residue with iodoacetic acid, 3-iodopropionic acid, or 4-bromobutyric acid. However, endoproteinase Lys-C digestion of modified glucoamylase followed by high-pressure liquid chromatography in combination with matrix-assisted laser desorption ionization/time-of-flight mass spectrometry on purified peptide fragments demonstrated that all enzyme derivatives contained the cysteinesulfinic acid oxidation product of Cys400. Subsequently, it was demonstrated that treatment of Glu400-->Cys glucoamylase with potassium iodide in the presence of bromine resulted in complete conversion to the cysteinesulfinic acid product. As expected, the catalytic base mutant Glu400-->Cys glucoamylase had very low activity, i.e., 0.2% compared to wild-type. The oxidation of Cys400 to cysteinesulfinic acid, however, restored activity (kcat) on alpha-1,4-linked substrates to levels up to 160% of the wild-type glucoamylase which corresponded to approximately a 700-fold increase in the kcat of the Glu400-->Cys mutant glucoamylase. Whereas Glu400-->Cys glucoamylase was much less thermostable and more sensitive to guanidinium chloride than the wild-type enzyme, the oxidation to cysteinesulfinic acid was accompanied by partial recovery of the stability.

  18. Microlith-Based Catalytic Reactor for Air Quality and Trace Contaminant Control Applications

    Science.gov (United States)

    Vilekar, Saurabh; Hawley, Kyle; Junaedi, Christian; Crowder, Bruce; Prada, Julian; Mastanduno, Richard; Perry, Jay L.; Kayatin, Matthew J.

    2015-01-01

    Traditionally, gaseous compounds such as methane, carbon monoxide, and trace contaminants have posed challenges for maintaining clean air in enclosed spaces such as crewed spacecraft cabins as they are hazardous to humans and are often difficult to remove by conventional adsorption technology. Catalytic oxidizers have provided a reliable and robust means of disposing of even trace levels of these compounds by converting them into carbon dioxide and water. Precision Combustion, Inc. (PCI) and NASA - Marshall (MSFC) have been developing, characterizing, and optimizing high temperature catalytic oxidizers (HTCO) based on PCI's patented Microlith® technology to meet the requirements of future extended human spaceflight explorations. Current efforts have focused on integrating the HTCO unit with a compact, simple recuperative heat exchanger to reduce the overall system size and weight while also reducing its energy requirements. Previous efforts relied on external heat exchangers to recover the waste heat and recycle it to the oxidizer to minimize the system's power requirements; however, these units contribute weight and volume burdens to the overall system. They also result in excess heat loss due to the separation of the HTCO and the heat recuperator, resulting in lower overall efficiency. Improvements in the recuperative efficiency and close coupling of HTCO and heat recuperator lead to reductions in system energy requirements and startup time. Results from testing HTCO units integrated with heat recuperators at a variety of scales for cabin air quality control and heat melt compactor applications are reported and their benefits over previous iterations of the HTCO and heat recuperator assembly are quantified in this paper.

  19. Simultaneous determination of trace iron and aluminum by catalytic spectrophotometry based on a novel oxidation reaction of xylene cyanol FF.

    Science.gov (United States)

    Cai, Longfei; Xu, Chunxiu

    2008-06-01

    A new, simple, sensitive and selective method for the simultaneous determination of trace iron and aluminum by catalytic spectrophotometry was presented, based on the catalytic effects of iron and aluminum on the discoloring reaction of xylene cyanol FF proceeded by hydrogen peroxide and potassium periodate in weak nitric acid medium. No catalytic effect was obtained in the presence of hydrogen peroxide or potassium periodate only. With the conditional rate constants determined in reaction systems catalyzed by Al or Fe only, the concentrations of Fe and Al in the samples can be calculated. The method was applied to the simultaneous determination of trace Fe and Al in tap water, lake water, river water and tea leaves without separation and preconcentration.

  20. Identification of acid-base catalytic residues of high-Mr thioredoxin reductase from Plasmodium falciparum.

    Science.gov (United States)

    McMillan, Paul J; Arscott, L David; Ballou, David P; Becker, Katja; Williams, Charles H; Müller, Sylke

    2006-11-03

    High-M(r) thioredoxin reductase from the malaria parasite Plasmodium falciparum (PfTrxR) contains three redox active centers (FAD, Cys-88/Cys-93, and Cys-535/Cys-540) that are in redox communication. The catalytic mechanism of PfTrxR, which involves dithiol-disulfide interchanges requiring acid-base catalysis, was studied by steady-state kinetics, spectral analyses of anaerobic static titrations, and rapid kinetics analysis of wild-type enzyme and variants involving the His-509-Glu-514 dyad as the presumed acid-base catalyst. The dyad is conserved in all members of the enzyme family. Substitution of His-509 with glutamine and Glu-514 with alanine led to TrxR with only 0.5 and 7% of wild type activity, respectively, thus demonstrating the crucial roles of these residues for enzymatic activity. The H509Q variant had rate constants in both the reductive and oxidative half-reactions that were dramatically less than those of wild-type enzyme, and no thiolateflavin charge-transfer complex was observed. Glu-514 was shown to be involved in dithiol-disulfide interchange between the Cys-88/Cys-93 and Cys-535/Cys-540 pairs. In addition, Glu-514 appears to greatly enhance the role of His-509 in acid-base catalysis. It can be concluded that the His-509-Glu-514 dyad, in analogy to those in related oxidoreductases, acts as the acid-base catalyst in PfTrxR.

  1. Simultaneous Elimination of Soot and NOX through Silver-Barium Based Catalytic Materials

    Directory of Open Access Journals (Sweden)

    Ganesh Chandra Dhal

    2017-04-01

    Full Text Available In this research paper, the nanometric size effect, the effects of the intrinsic factors including structure, and the redox properties of three systems of nanometric of silver-based catalysts were summarized. In this work, these catalysts were investigated for the simultaneous removal of particulate matter (diesel soot, and NOX was compared with that of a model of Pt-Ba/Al2O3 catalyst. The Silver-Barium based catalytic materials of Ag (5 wt%-Ba(10 wt%/MO (MO=Al2O3, CeO2, ZrO2, and Ag (5 wt%-Sr (10 wt%/CeO2 catalysts have been prepared by wetness impregnation method and characterized by BET, XRD, HRTEM, XPS and TPR (temperature-programmed reduction experiments. The behavior of the catalyst in the soot combustion (under tight conditions and NOX elimination has been separately analyzed by means of temperature programmed oxidation and isothermal concentration step change experiments, respectively. The results showed that all the catalysts were active in soot combustion with an indicative decrease of oxidation onset temperature compared to uncatalyzed soot oxidation. The removal of NOX in the presence and in the absence of soot was investigated under cycling conditions, i.e. alternating lean-rich phases according to the LNT approach. It has been found that the Ag-based samples were able to simultaneously remove soot and NOX. In particular, studying the behavior of the prepared catalysts, the Ba-containing systems exhibited higher NOX storage capacity than Sr-catalyst; also, the nitrogen selectivity increased even if resulted lower than the traditional LNT Pt-based catalyst. An adverse effect of soot on the NOX storage activity has been also observed. Copyright © 2017 BCREC GROUP. All rights reserved Received: 18th August 2016; Revised: 19th October 2016; Accepted: 19th October 2016 How to Cite: Dhal, G.C., Dey, S., Prasad, R., Mohan, D. (2017. Simultaneous Elimination of Soot and NOX through Silver-Barium Based Catalytic Materials. Bulletin of

  2. Synthesis of novel chiral tridentate Schiff-base ligands and their applications in catalytic asymmetric Henry reaction.

    Science.gov (United States)

    Qiang, Gen-Rong; Shen, Tian-Hua; Zhou, Xiao-Cong; An, Xiao-Xia; Song, Qing-Bao

    2014-12-01

    A series of chiral tridentate Schiff-bases were prepared and used as ligands in the catalytic asymmetric Henry reaction. Under the optimal conditions, a variety of arylaldehydes were smoothly converted into corresponding adducts with high yields (up to 98%) and excellent enantioselectivities (up to 97% ee).

  3. Chloride ions promoted the catalytic wet peroxide oxidation of phenol over clay-based catalysts.

    Science.gov (United States)

    Zhou, Shiwei; Zhang, Changbo; Xu, Rui; Gu, Chuantao; Song, Zhengguo; Xu, Minggang

    2016-01-01

    Catalytic wet peroxide oxidation (CWPO) of phenol over clay-based catalysts in the presence and absence of NaCl was investigated. Changes in the H2O2, Cl(-), and dissolved metal ion concentration, as well as solution pH during phenol oxidation, were also studied. Additionally, the intermediates formed during phenol oxidation were detected by liquid chromatography-mass spectroscopy and the chemical bonding information of the catalyst surfaces was analyzed by X-ray photoelectron spectroscopy (XPS). The results showed that the presence of Cl(-) increased the oxidation rate of phenol to 155%, and this phenomenon was ubiquitous during the oxidation of phenolic compounds by H2O2 over clay-based catalysts. Cl(-)-assisted oxidation of phenol was evidenced by several analytical techniques such as mass spectroscopy (MS) and XPS, and it was hypothesized that the rate-limiting step was accelerated in the presence of Cl(-). Based on the results of this study, the CWPO technology appears to be promising for applications in actual saline phenolic wastewater treatment.

  4. Ruthenium(II) hydrazone Schiff base complexes: synthesis, spectral study and catalytic applications.

    Science.gov (United States)

    Manikandan, R; Viswanathamurthi, P; Muthukumar, M

    2011-12-01

    Ruthenium(II) hydrazone Schiff base complexes of the type [RuCl(CO)(B)(L)] (were B=PPh(3), AsPh(3) or Py; L=hydrazone Schiff base ligands) were synthesized from the reactions of hydrazone Schiff base ligand (obtained from isonicotinoylhydrazide and different hydroxy aldehydes) with [RuHCl(CO)(EPh(3))(2)(B)] (where E=P or As; B=PPh(3), AsPh(3) or Py) in 1:1 molar ratio. All the new complexes have been characterized by analytical and spectral (FT-IR, electronic, (1)H, (13)C and (31)P NMR) data. They have been tentatively assigned an octahedral structure. The synthesized complexes have exhibited catalytic activity for oxidation of benzyl alcohol to benzaldehyde and cyclohexanol to cyclohexanone in the presence of N-methyl morpholine N-oxide (NMO) as co-oxidant. They were also found to catalyze the transfer hydrogenation of aliphatic and aromatic ketones to alcohols in KOH/Isopropanol.

  5. Characteristics-based model predictive control of a catalytic flow reversal reactor

    Energy Technology Data Exchange (ETDEWEB)

    Fuxman, A.M.; Forbes, J.F.; Hayes, R.E. [Alberta Univ., Edmonton, AB (Canada). Dept. of Chemical and Materials Engineering

    2007-08-15

    A model-based controller for a catalytic flow reversal reactor (CFRR) was presented. The characteristics-based model predictive control (CBMPC) was used to provide greater accuracy in the prediction of process output variables as well as to ensure the maintenance of safe operating temperatures. Performance of the CBMPC was simulated in order to evaluate combustion of lean methane streams for the reduction of greenhouse gas (GHG) emissions. Dynamics of the CFRR were described using partial differential equations (PDEs) derived from mass and energy balances. The PDEs were then transformed into an equivalent lumped parameter model, which was in turn used to design the non-linear predictive controller. The prediction horizon was divided into Hp intervals during each half cycle. A constrained quadratic program was then solved to obtain an optimal input sequence. The strategy was then evaluated by applying it to a simple CFRR plant, as well as a more complex plant modelled by a dynamical-dimensional heterogenous model that incorporated the effect of a large insulation layer needed to reduce heat loss from the reactor. Results of the simulations suggested that mass extraction in a CBMPC scheme can be used to maintain safe operating conditions. It was concluded that the strategy provided good control performance for regulation and set point tracking in the presence of inlet disturbances and other changes in operating conditions. 18 refs., 1 tab., 10 figs.

  6. Biomass Catalytic Pyrolysis with Ni Based Catalyst to Produce Hydrogen Rich Gas

    Institute of Scientific and Technical Information of China (English)

    WANG Mingfeng; LIU Min; XU Xiwei; LI Bosong; ZHANG Qiang; JIAN Enchen

    2010-01-01

    Hydrogen rich gas was produced using rice husk as biomass material on the continuous biomass pyrolysis apparatus which consisted of continuous pyrolysis reactor and secondary catalytic cracking reactor. Ni based catalysts of different Ni/Al mass ratio and calcined temperature were prepared by impregnating method. The catalysts were characterized by X-ray diffraction (XRD),scan electron microscope (SEM) and FT-IR Spectrometer (FT-IR). Ni based catalyst showed good selectivity for H2 production from biomass. Catalysts prepared under different conditions had little influence on the yields of three states products when used at the same cracking temperature. Ni/Al mass ratio played an important role in products selectivity. However, the content of NiO increased further when Ni/Al mass ratio values reached 0.7 : 10, and the yield of H2 slightly increased. Hydrogen yield was greatly impacted by calcined temperature. Catalyst calcined at 550"C performed best. When the catalyst was calcined at high temperature, NiO in the catalyst transformed into NiAl2O4, and the acid site also changed, which caused the deactivation of the catalyst. The hydrogen yield increased with the cracking temperature. The highest stable yield of hydrogen was about 30% without increasing with the cracking temperature.

  7. Development of biomimetic catalytic oxidation methods and non-salt methods using transition metal-based acid and base ambiphilic catalysts.

    Science.gov (United States)

    Murahashi, Shun-Ichi

    2011-01-01

    This review focuses on the development of ruthenium and flavin catalysts for environmentally benign oxidation reactions based on mimicking the functions of cytochrome P-450 and flavoenzymes, and low valent transition-metal catalysts that replace conventional acids and bases. Several new concepts and new types of catalytic reactions based on these concepts are described. (Communicated by Ryoji Noyori, M.J.A.).

  8. Hydrogen-based tubular catalytic membrane for removing nitrate from groundwater.

    Science.gov (United States)

    Chen, Y X; Zhang, Y; Liu, H Y; Sharma, K R; Chen, G H

    2004-02-01

    A porous tubular ceramic membrane coated with palladium-cupper (Pd-Cu) catalyst on its surface was prepared and evaluated for catalytic reduction of nitrate from groundwater. Nitrate reduction activity and selectivity with the catalytic membrane were compared with Pd-Cu/Al2O3 catalyst particles. The catalytic membrane reactor exhibited a better selectivity by enabling an effective control of hydrogen gas, thus minimizing ammonium production. No leaching of palladium and copper into aqueous phase was observed, thereby indicating a high chemical stability of the metallic ions on the carrier support. This was also evidenced by the X-ray photoelectron spectroscopy (XPS) profiles of fresh and used catalysts, which showed no significant difference in surface compositions. Due to its higher selectivity in nitrate reduction and better flexibility in terms of operating conditions, the tubular catalytic ceramic membrane could be useful in removing nitrate from groundwater.

  9. Catalytic behavior of Sn/Bi metal powder in anhydride-based epoxy curing.

    Science.gov (United States)

    Jang, Keon-Soo; Eom, Yong-Sung; Moon, Jong-Tae; Oh, Yong-Soo; Nam, Jae-Do

    2009-12-01

    In this paper, we report the catalytic activity of the Sn/Bi alloy beads and its acceleration of the exothermic epoxy curing reactions in various thermal conditions and bead compositions. As being used as low-melting solder balls in electronic interconnection processes with various epoxy systems, it was found that the Sn/Bi beads substantially lowered the exothermic peak temperature of the diglycidyl ether of bisphenol A (DGEBA)/anhydride systems in up to ca. 140 degrees C depending on different types of anhydride curing agents. The catalytic activation of Sn/Bi powder was initiated with a small amount of Sn/Bi powder, for example, lowering ca. 50 degrees C of the exothermic peak temperature by adding only 0.1 vol% of Sn/Bi powder. The catalytic capability of the powder was increased by using smaller sized beads corresponding to larger catalytic surface area at the same volume fraction. Exhibiting a latent catalytic effect, the catalytic activity of Sn/Bi powder was remained latent at temperatures lower than 100 degrees C in isothermal conditions.

  10. Catalytic mechanism of LENR in quasicrystals based on localized anharmonic vibrations and phasons

    CERN Document Server

    Dubinko, Volodymyr; Irwin, Klee

    2016-01-01

    Quasicrystals (QCs) are a novel form of matter, which are neither crystalline nor amorphous. Among many surprising properties of QCs is their high catalytic activity. We propose a mechanism explaining this peculiarity based on unusual dynamics of atoms at special sites in QCs, namely, localized anharmonic vibrations (LAVs) and phasons. In the former case, one deals with a large amplitude (~ fractions of an angstrom) time-periodic oscillations of a small group of atoms around their stable positions in the lattice, known also as discrete breathers, which can be excited in regular crystals as well as in QCs. On the other hand, phasons are a specific property of QCs, which are represented by very large amplitude (~angstrom) oscillations of atoms be-tween two quasi-stable positions determined by the geometry of a QC. Large amplitude atomic motion in LAVs and phasons results in time-periodic driving of adjacent potential wells occupied by hydrogen ions (protons or deuterons) in case of hydrogenated QCs. This drivin...

  11. High performance anodes with tailored catalytic properties for La5.6WO11.4-δ based proton conducting fuel cells

    DEFF Research Database (Denmark)

    Balaguer, M.; Solis, C.; Bozza, Francesco;

    2013-01-01

    A new generation of anodes for PC-SOFCs based on catalytically promoted La0.75Ce0.1Sr0.15CrO3−δ (LSCCe) is presented. LSCCe is selected as the electrode backbone structure, due to its superior total conductivity over that of LSC. The infiltration of catalytically highly active nickel nanoparticles...

  12. Synthesis and catalytic activity of Ln(III) complexes with an unsymmetrical Schiff base including multigroups

    Institute of Scientific and Technical Information of China (English)

    YAO; Kemin; (

    2003-01-01

    [1]Elder, R. C., Tridentate and unsymmetrical tetradentate Schiff base ligands from salicylaldehydes and dimeric nickel(II) complexes, Aust. J. Chem., 1978, 31:35-45.[2]Atkins, R., Brewer, G., Kokot, G. et al., Copper(II) and nickel(II) complexesof unsymmetrical tetradentate Schiff base ligand, Inorg. Chem., 1985, 24: 127-134.[3]Meng Qingjin, Wang Ruixue, Bu Xiuren et al., New Ni (II) complexes with mixedtrimeric double Schiff ligands, Chemical Journal of Chinese Universities (in Chinese), 1990, 10: 1126-1130.[4]Yao Kemin, Zhou Wen, Lu Gui et al., Synthesis, mechanism and NMR spectra of lanthanide complexes with a novel unsymmetrical Schiff base, Science in China, Series B, 1999, 42(2): 164-169.[5]Yao Kemin, Li Ning, Huang Qiaohong et al., Synthesis and catalytic activity of novel heteronuclear Ln(III)-Cu(II) complexes with noncyclic polyether-amino acid Schiff base, Science in China, Series B, 1999, 42 (1) : 54-81.[6]Li Ning, Yao Kemin, Lou Kaiyan, Synthesis of La(III), Y(III) complexes with polyglycol aldehyde-amino acid Schiff base and their high resolution solid state 13C NMR spectra, Science in China, Series B, 1999, 42(6): 599-604.[7]Lam Berf, J. B., Shurvell, H. F., Verbet, L. et al., Organic Structural Analysis, New York: Macmillan Publishing Co. Inc., 1975, 234-250.[8]Yao Kemin, Cai Lezhen, Shen Liangfang et al., Synthesis and characterization of lanthanide perchlorates with noncyclic polyethylene glycols and their 13C-NMRspectra, Polyhedron, 1992,11(7): 2245-2251.[9]Dewar, M. J. S., Zoebisch, E. G., Healy, E. F., AM1: A new general purpose quantum mechanical molecular model, J. Amer. Chem. Soc., 1985, 107: 3902-3909.[10]Feifer, P., Avnjr, D., Chemistry in noninteger dimensions between two and three, I. Fractal theory of heterogeneous surfaces, J. Chem. Phys., 1983, 79(7): 3558-3565.[11]Yang Haifeng, Wang Hui, Duan Jinxia et al., Ab initio research of organic ligand Schiff base 4-[(2-hydroxyphenyl) imine]-2

  13. Direct methane solid oxide fuel cells based on catalytic partial oxidation enabling complete coking tolerance of Ni-based anodes

    Science.gov (United States)

    Lee, Daehee; Myung, Jaeha; Tan, Jeiwan; Hyun, Sang-Hoon; Irvine, John T. S.; Kim, Joosun; Moon, Jooho

    2017-03-01

    Solid oxide fuel cells (SOFCs) can oxidize diverse fuels by harnessing oxygen ions. Benefited by this feature, direct utilization of hydrocarbon fuels without external reformers allows for cost-effective realization of SOFC systems. Superior hydrocarbon reforming catalysts such as nickel are required for this application. However, carbon coking on nickel-based anodes and the low efficiency associated with hydrocarbon fueling relegate these systems to immature technologies. Herein, we present methane-fueled SOFCs operated under conditions of catalytic partial oxidation (CPOX). Utilizing CPOX eliminates carbon coking on Ni and facilitates the oxidation of methane. Ni-gadolinium-doped ceria (GDC) anode-based cells exhibit exceptional power densities of 1.35 W cm-2 at 650 °C and 0.74 W cm-2 at 550 °C, with stable operation over 500 h, while the similarly prepared Ni-yttria stabilized zirconia anode-based cells exhibit a power density of 0.27 W cm-2 at 650 °C, showing gradual degradation. Chemical analyses suggest that combining GDC with the Ni anode prevents the oxidation of Ni due to the oxygen exchange ability of GDC. In addition, CPOX operation allows the usage of stainless steel current collectors. Our results demonstrate that high-performance SOFCs utilizing methane CPOX can be realized without deterioration of Ni-based anodes using cost-effective current collectors.

  14. Ultrasensitive colorimetric detection of Cu2+ ion based on catalytic oxidation of L-cysteine.

    Science.gov (United States)

    Yin, Kun; Li, Bowei; Wang, Xiaochun; Zhang, Weiwei; Chen, Lingxin

    2015-02-15

    As an essential element, copper ion (Cu(2+)) plays important roles in human beings for its participation in diverse metabolic processes as a cofactor and/or a structural component of enzymes. However, excessive uptake of Cu(2+) ion gives rise to the risk of certain diseases. So, it is important to develop simple ways to monitor and detect Cu(2+) ion. In this study, a simple, facile colorimetric sensor for the ultrasensitive determination of Cu(2+) ion was developed based on the following principle: L-cysteine and 1-chloro-2,4-dinitrobenzene (CDNB) could be conjugated to form the yellow product 2,4-dinitrophenylcysteine (DNPC), which was measurable at 355nm; however, upon addition of Cu(2+) ion, the absorbance of DNPC would be decreased owing to the Cu(2+) ion catalytic oxidation of L-cysteine to L-cystine in the presence of O2. Thus, the colorimetric detection of Cu(2+) ion could be achieved. The optimal pH, buffer, temperature and incubation time for the colorimetric sensor were obtained of pH 6.8 in 0.1M HEPES solution, 90 °C and 50 min, respectively. A good linearity within the range of 0.8-10 nM (r = 0.996) was attained, with a high detectability up to 0.5nM. Analyses of Cu(2+) ion in drinking water, lake water, seawater and biological samples were carried out and the method performances were found to agree well with that obtained by ICP-MS. The developed simple colorimetric sensor proved applicable for Cu(2+) ion determination in real samples with high sensitivity and selectivity.

  15. Principles of water oxidation and O2-based hydrocarbon transformation by multinuclear catalytic sites

    Energy Technology Data Exchange (ETDEWEB)

    Musaev, Djamaladdin G [Chemistry, Emory University; Hill, Craig L [Chemistry, Emory University; Morokuma, Keiji [Chemistry, Emory University

    2014-10-28

    Abstract The central thrust of this integrated experimental and computational research program was to obtain an atomistic-level understanding of the structural and dynamic factors underlying the design of catalysts for water oxidation and selective reductant-free O2-based transformations. The focus was on oxidatively robust polyoxometalate (POM) complexes in which a catalytic active site interacts with proximal metal centers in a synergistic manner. Thirty five publications in high-impact journals arose from this grant. I. Developing an oxidatively and hydrolytically stable and fast water oxidation catalyst (WOC), a central need in the production of green fuels using water as a reductant, has proven particularly challenging. During this grant period we have designed and investigated several carbon-free, molecular (homogenous), oxidatively and hydrolytically stable WOCs, including the Rb8K2[{Ru4O4(OH)2(H2O)4}(γ-SiW10O36)2]·25H2O (1) and [Co4(H2O)2(α-PW9O34)2]10- (2). Although complex 1 is fast, oxidatively and hydrolytically stable WOC, Ru is neither abundant nor inexpensive. Therefore, development of a stable and fast carbon-free homogenous WOC, based on earth-abundant elements became our highest priority. In 2010, we reported the first such catalyst, complex 2. This complex is substantially faster than 1 and stable under homogeneous conditions. Recently, we have extended our efforts and reported a V2-analog of the complex 2, i.e. [Co4(H2O)2(α-VW9O34)2]10- (3), which shows an even greater stability and reactivity. We succeeded in: (a) immobilizing catalysts 1 and 2 on the surface of various electrodes, and (b) elucidating the mechanism of O2 formation and release from complex 1, as well as the Mn4O4L6 “cubane” cluster. We have shown that the direct O-O bond formation is the most likely pathway for O2 formation during water oxidation catalyzed by 1. II. Oxo transfer catalysts that contain two proximal and synergistically interacting redox active metal

  16. Two Gd(III) coordination polymers based on a flexible tricarboxylate: Syntheses, structures, luminescence and catalytic properties

    Science.gov (United States)

    Zhu, Yu; Zhu, Min; Liu, Pan; Xia, Li; Wu, Yunlong; Xie, Jimin

    2017-02-01

    Two Gadolinium coordination polymers {[Gd·(TTTA)·(H2O)2]·2H2O}n (1) and [Gd·(TTTA)·DMF]n (2) have been synthesized based on Gd(NO3)3·6H2O and the flexible tripodal ligand 2,2‧,2″-[1,3,5-triazine-2,4,6-triyltris(thio)]tris-acetic acid (H3TTTA) under hydrothermal conditions. In the structure of 1, the tridentate TTTA3- ligands connect the dimeric metal centers into an infinite one dimensional chain. While 2 shows a two dimensional network with tridentate TTTA3- ligands. The two complexes all quench the emission spectra after coordinated to the Gd3+ ions. The catalytic results indicate that two complexes show excellent activities for the cyanosilylation of benzaldehyde and its derivatives. Besides, 2 is better than 1 in the catalytic reactions due to more possibility of metal open sites.

  17. In situ synchrotron-based IR microspectroscopy to study catalytic reactions in zeolite crystals

    NARCIS (Netherlands)

    Stavitski, Eli; Kox, Marianne H. F.; Swart, Ingmar; de Groot, Frank M. F.; Weckhuysen, Bert M.

    2008-01-01

    In recent years a number of in situ microspectroscopic techniques have been explored to investigate catalytic reactions taking place in heterogeneous catalysts in a timeand space-resolved manner.[1–8] These spectroscopic methods have proven to be very successful in elucidating valuable structure–fun

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

    Directory of Open Access Journals (Sweden)

    Irene Lock Sow Mei

    2016-08-01

    Full Text Available Hydrogen production from the direct thermo-catalytic decomposition of methane is a promising alternative for clean fuel production. However, thermal decomposition of methane can hardly be of any practical and empirical interest in the industry unless highly efficient and effective catalysts, in terms of both catalytic activity and operational lifetime have been developed. In this study, the effect of palladium (Pd as a promoter onto Ni supported on alumina catalyst has been investigated by using co-precipitation technique. The introduction of Pd promotes better catalytic activity, operational lifetime and thermal stability of the catalyst. As expected, highest methane conversion was achieved at reaction temperature of 800 °C while the bimetallic catalyst (1 wt.% Ni -1wt.% Pd/Al2O3 gave the highest methane conversion of 70% over 15 min of time-on-stream (TOS. Interestingly, the introduction of Pd as promoter onto Ni-based catalyst also has a positive effect on the operational lifetime and thermal stability of the catalyst as the methane conversion has improved significantly over 240 min of TOS. Copyright © 2016 BCREC GROUP. All rights reserved Received: 21st January 2016; Revised: 6th February 2016; Accepted: 6th March 2016 How to Cite: Mei, I.L.S., Lock, S.S.M., Vo, D.V.N., Abdullah, B. (2016. Thermo-Catalytic Methane Decomposition for Hydrogen Production: Effect of Palladium Promoter on Ni-based Catalysts. Bulletin of Chemical Reaction Engineering & Catalysis, 11 (2: 191-199 (doi:10.9767/bcrec.11.2.550.191-199 Permalink/DOI: http://dx.doi.org/10.9767/bcrec.11.2.550.191-199

  19. Efficient H{sub 2}-producing photo-catalytic systems based on cyclo-metallated iridium- and tricarbonyl-rhenium-diimine photosensitizers and cobaloxime catalysts

    Energy Technology Data Exchange (ETDEWEB)

    Fihri, A.; Artero, V.; Fontecave, M. [Univ Grenoble 1, Lab Chim et Biol Metaux, Grenoble (France); Fihri, A.; Artero, V.; Fontecave, M. [CNRS, UMR 5249, F-75700 Paris (France); Fihri, A.; Artero, V.; Fontecave, M. [CEA, DSV, iRTSV, F-38054 Grenoble 9 (France); Pereira, A. [CEA, DRT, Liten, DTNM, LTS, Grenoble (France)

    2008-07-01

    Quantum yield values up to 16% under visible irradiation associated with high turnover frequencies ({approx} 50 h{sup -1}) and stability (up to 273 turnovers), characterize the new photo-catalytic systems for hydrogen production, based on diimine derivatives of ruthenium, cyclo-metallated iridium or tricarbonyl-rhenium as photosensitizers and cobaloxime H{sub 2}-evolving catalytic centers, which are among the most efficient molecular systems reported so far and compete with some platinum-based systems. (authors)

  20. Development Of Hot Surface Polysilicon-Based Chemical Sensor And Actuator With Integrated Catalytic Micropatterns For Gas Sensing Applications

    Science.gov (United States)

    Vereshchagina, E.; Gardeniers, J. G. E.

    2009-05-01

    Over the last twenty years, we have followed a rapid expansion in the development of chemical sensors and microreactors for detection and analysis of volatile organic compounds. However, for many of the developed gas sensors poor sensitivity and selectivity, and high-power consumption remain among one of the main drawbacks. One promising approach to increase selectivity at lower power consumption is calorimetric sensing, performed in a pulsed regime and using specific catalytic materials. In this work, we study kinetics of various catalytic oxidation reactions using micromachined hot surface polysilicon-based sensor containing sensitive and selective catalysts. The sensor acts as both thermal actuator of chemical and biochemical reactions on hot-surfaces and detector of heats (enthalpies) associated with these reactions. Using novel deposition techniques we integrated selective catalysts in an array of hot plates such that they can be thermally actuated and sensed individually. This allows selective detection and analysis of dangerous gas compounds in a mixture, specifically hydrocarbons at concentrations down to low ppm level. In this contribution we compare various techniques for the local immobilization of catalytic material on hot spots of the sensor in terms of process compatibility, mechanical stress, stability and cost.

  1. Effect of BaO on catalytic performance of Pd-based catalysts for purification of gasoline-methanol exhaust

    Institute of Scientific and Technical Information of China (English)

    张雪乔; 赵明; 徐成华; 汪嘉扬; 陈耀强

    2014-01-01

    Barium oxide was developed successfully to modify palladium catalysts supported on CeO2-ZrO2-La2O3-Al2O3 (CZLA) compound oxides by impregnation method. N2 adsorption (BET), X-ray diffraction (XRD), H2-temperature-programmed reduction (H2-TPR) and X-ray photoelectron spectroscopy (XPS) were employed to characterize the influence of BaO on the physicochemical properties of catalyst. And catalytic activity tests for methanol, CO, C3H8 and NO conversion were evaluated. Catalytic activity re-sults showed that BaO had a positive effect on the conversion of all pollutants. H2-TPR results suggested that the addition of BaO in-creased the reductive ability of the palladium catalysts. The XPS results indicated that doping BaO also improved the dispersion of Pd species and increased the amounts of Ce3+on the Pd-Ba/CZLA catalyst surface, which led to a better redox property. The excellent redox property helped to improve the catalytic activities toward all the pollutants over Pd-based catalysts.

  2. Catalytic Oxidative Decarboxylation of Some Benzylcarboxylic Acid Derivatives by a New Iron(Ill) Schiff Base Complex

    Institute of Scientific and Technical Information of China (English)

    MONTAZEROZOHORI,Morteza; NASR-ESFAHANI,Masoud; AKHLAGHI,Parisa

    2009-01-01

    A quadridentate Schiff base ligand of N,N'-bis(2-hydroxy-a-methylbenzylidene)ethylenediamine (HMBEDA) and its new iron(Ⅲ) complex were synthesized and identified by analytical, spectral data (1H NMR, 13C NMR FT-IR and UV-visible) and molar conductance. A rapid and efficient homogeneous oxidative decarboxylatio n ofsome benzylcarboxylic acid derivatives was carried out by a catalytic amount of iron(Ⅲ) Schiff base complex in chloroform, using tetrabutylammonium periodate as a mild oxidant in good to excellent yields at room temperature.

  3. Selective catalytic reduction of nitrogen oxides from industrial gases by hydrogen or methane; Reduction catalytique selective des oxydes d'azote (NO{sub x}) provenant d'effluents gazeux industriels par l'hydrogene ou le methane

    Energy Technology Data Exchange (ETDEWEB)

    Engelmann Pirez, M

    2004-12-15

    This work deals with the selective catalytic reduction of nitrogen oxides (NO{sub x}), contained in the effluents of industrial plants, by hydrogen or methane. The aim is to replace ammonia, used as reducing agent, in the conventional process. The use of others reducing agents such as hydrogen or methane is interesting for different reasons: practical, economical and ecological. The catalyst has to convert selectively NO into N{sub 2}, in presence of an excess of oxygen, steam and sulfur dioxide. The developed catalyst is constituted by a support such as perovskites, particularly LaCoO{sub 3}, on which are dispersed noble metals (palladium, platinum). The interaction between the noble metal and the support, generated during the activation of the catalyst, allows to minimize the water and sulfur dioxide inhibitor phenomena on the catalytic performances, particularly in the reduction of NO by hydrogen. (O.M.)

  4. Direct catalytic asymmetric addition of allyl cyanide to ketones via soft Lewis acid/hard Brønsted base/hard Lewis base catalysis.

    Science.gov (United States)

    Yazaki, Ryo; Kumagai, Naoya; Shibasaki, Masakatsu

    2010-04-21

    We report that a hard Lewis base substantially affects the reaction efficiency of direct catalytic asymmetric gamma-addition of allyl cyanide (1a) to ketones promoted by a soft Lewis acid/hard Brønsted base catalyst. Mechanistic studies have revealed that Cu/(R,R)-Ph-BPE and Li(OC(6)H(4)-p-OMe) serve as a soft Lewis acid and a hard Brønsted base, respectively, allowing for deprotonative activation of 1a as the rate-determining step. A ternary catalytic system comprising a soft Lewis acid/hard Brønsted base and an additional hard Lewis base, in which the basicity of the hard Brønsted base Li(OC(6)H(4)-p-OMe) was enhanced by phosphine oxide (the hard Lewis base) through a hard-hard interaction, outperformed the previously developed binary soft Lewis acid/hard Brønsted base catalytic system, leading to higher yields and enantioselectivities while using one-tenth the catalyst loading and one-fifth the amount of 1a. This second-generation catalyst allows efficient access to highly enantioenriched tertiary alcohols under nearly ideal atom-economical conditions (0.5-1 mol % catalyst loading and a substrate molar ratio of 1:2).

  5. Principles of water oxidation and O2-based hydrocarbon transformation by multinuclear catalytic sites

    Energy Technology Data Exchange (ETDEWEB)

    Musaev, Djamaladdin G [Chemistry, Emory University; Hill, Craig L [Chemistry, Emory University; Morokuma, Keiji [Chemistry, Emory University

    2014-10-28

    Abstract The central thrust of this integrated experimental and computational research program was to obtain an atomistic-level understanding of the structural and dynamic factors underlying the design of catalysts for water oxidation and selective reductant-free O2-based transformations. The focus was on oxidatively robust polyoxometalate (POM) complexes in which a catalytic active site interacts with proximal metal centers in a synergistic manner. Thirty five publications in high-impact journals arose from this grant. I. Developing an oxidatively and hydrolytically stable and fast water oxidation catalyst (WOC), a central need in the production of green fuels using water as a reductant, has proven particularly challenging. During this grant period we have designed and investigated several carbon-free, molecular (homogenous), oxidatively and hydrolytically stable WOCs, including the Rb8K2[{Ru4O4(OH)2(H2O)4}(γ-SiW10O36)2]·25H2O (1) and [Co4(H2O)2(α-PW9O34)2]10- (2). Although complex 1 is fast, oxidatively and hydrolytically stable WOC, Ru is neither abundant nor inexpensive. Therefore, development of a stable and fast carbon-free homogenous WOC, based on earth-abundant elements became our highest priority. In 2010, we reported the first such catalyst, complex 2. This complex is substantially faster than 1 and stable under homogeneous conditions. Recently, we have extended our efforts and reported a V2-analog of the complex 2, i.e. [Co4(H2O)2(α-VW9O34)2]10- (3), which shows an even greater stability and reactivity. We succeeded in: (a) immobilizing catalysts 1 and 2 on the surface of various electrodes, and (b) elucidating the mechanism of O2 formation and release from complex 1, as well as the Mn4O4L6 “cubane” cluster. We have shown that the direct O-O bond formation is the most likely pathway for O2 formation during water oxidation catalyzed by 1. II. Oxo transfer catalysts that contain two proximal and synergistically interacting redox active metal

  6. Study on Carbon Nanotubes Prepared from Catalytic Decomposition of CH4 over Lanthanum Containing Ni-Base Catalysts

    Institute of Scientific and Technical Information of China (English)

    Wang Minwei; Li Fengyi

    2004-01-01

    A series of lanthanum containing Ni-base catalysts were prepared by citric acid complex method.Carbon nanotubes (CNT) were synthesized bY catalytic decomposing CH4 over these catalysts and characterized by XRD, TEM and TGA.It is found that the addition of lanthanum can not increase the yield of carbon nanotube, but can make the diameter of carbon nanotube thinner and even.The more the lanthanum addsr, the thinner the diameter of CNTs becomes.With the CNTs prepared on Ni-Mg catalyst, the CNTs prepared on Ni-La-Mg catalyst has better crystallinity and thermal stability.

  7. New Element Organic Frameworks Based on Sn, Sb, and Bi, with Permanent Porosity and High Catalytic Activity

    Directory of Open Access Journals (Sweden)

    Julia Fritsch

    2010-03-01

    Full Text Available We present new element organic frameworks based on Sn, Sb and Bi atoms connected via organic linkers by element-carbon bonds. The open frameworks are characterized by specific surface areas (BET of up to 445 m2 g-1 and a good stability under ambient conditions resulting from a highly hydrophobic inner surface. They show good performance as heterogeneous catalysts in the cyanosylilation of benzaldehyde as a test reaction. Due to their catalytic activity, this class of materials might be able to replace common homogeneous element-organic and often highly toxic catalysts especially in the food industry.

  8. System and method for controlling an engine based on ammonia storage in multiple selective catalytic reduction catalysts

    Energy Technology Data Exchange (ETDEWEB)

    Sun, MIn; Perry, Kevin L.

    2015-11-20

    A system according to the principles of the present disclosure includes a storage estimation module and an air/fuel ratio control module. The storage estimation module estimates a first amount of ammonia stored in a first selective catalytic reduction (SCR) catalyst and estimates a second amount of ammonia stored in a second SCR catalyst. The air/fuel ratio control module controls an air/fuel ratio of an engine based on the first amount, the second amount, and a temperature of a substrate disposed in the second SCR catalyst.

  9. Low temperature selective catalytic reduction of NOx with NH3 over Mn-based catalyst: A review

    Directory of Open Access Journals (Sweden)

    TsungYu Lee

    2016-05-01

    Full Text Available The removals of NOx by catalytic technology at low temperatures (100–300 °C for industrial flue gas treatment have received increasing attention. However, the development of low temperature catalysts for selective catalytic reduction (SCR of NOx with ammonia is still a challenge especially in the presence of SO2. The current status of using Mn-based catalysts for low temperature SCR of NOx with ammonia (NH3-SCR is reviewed. Reaction mechanisms and effects of operating factors on low temperature NH3-SCR are addressed, and the SCR efficiencies of Mn-based metal oxides with and without SO2 poisoning have also been discussed with different supports and co-metals. The key factors for enhancing low temperature NH3-SCR efficiency and SO2 resistance with Mn-based catalysts are identified to be (1 high specific surface area; (2 high surface acidity; (3 oxidation states of manganese; (4 well dispersion of manganese oxide metals; (5 more surface adsorbed oxygen; (6 more absorbed NO3− on the catalyst surface; (7 easier decomposition of ammonium sulfates. Moreover, the regenerative methods such as water washing, acid and/or alkali washing and heat treatment to the poisoned catalysts could help to recover the low temperature SCR efficiency to its initial level.

  10. Herbo-mineral based Schiff base ligand and its metal complexes: Synthesis, characterization, catalytic potential and biological applications.

    Science.gov (United States)

    Kareem, Abdul; Laxmi; Arshad, Mohammad; Nami, Shahab A A; Nishat, Nahid

    2016-07-01

    Schiff base ligand, (L), derived from condensation reaction of 1,7-bis-(4-hydroxy-3-methoxyphenyl)-1,6-heptadiene-3,5-dione, (curcumin), with pyridine-3-carboxamide, (nicotinamide), and its complexes of Co(II), Ni(II) and Cu(II) ions, containing 1,10-phenanthroline as auxiliary ligand were synthesized and characterized by various physico-chemical techniques. From the micro analytical data, the stoichiometry of the complexes 1:1 (metal: ligand) was ascertained. The Co(II) and Cu(II) forms octahedral complexes, while the geometric structure around Ni(II) atom can be described as square planar. The catalytic potential of the metal complexes have been evaluated by recording the rate of decomposition of hydrogen peroxide. The results reveal that the percent decomposition of H2O2increases with time and the highest value (50.50%) was recorded for Co(II) complex. The ligand and its complexes were also screened for their in vitro antibacterial activity against Escherichia coli, Staphylococcus aureus, Klebsiella pneumoniae, Streptococcus pyogenes and Pseudomonas aeruginosa. The relative order of antibacterial activity against S. Pyogenes, S. aureus and E. coli is Cu(II)>Ni(II)>Co(II)>(L); while with P. aeruginosa, K. pneumoniae the order of activity is Cu(II)>Co(II)>Ni(II)>(L). The anthelmintic screening was performed using Pheretima posthuma. The order of anthelmintic activity of ligand and its complexes is [(Phen)CuLCl2]>[(Phen)CoLCl2]>[(Phen)NiL]Cl2>(L).

  11. Heterogeneous catalytic ozonation of biologically pretreated Lurgi coal gasification wastewater using sewage sludge based activated carbon supported manganese and ferric oxides as catalysts.

    Science.gov (United States)

    Zhuang, Haifeng; Han, Hongjun; Hou, Baolin; Jia, Shengyong; Zhao, Qian

    2014-08-01

    Sewage sludge of biological wastewater treatment plant was converted into sewage sludge based activated carbon (SBAC) with ZnCl₂ as activation agent, which supported manganese and ferric oxides as catalysts (including SBAC) to improve the performance of ozonation of real biologically pretreated Lurgi coal gasification wastewater. The results indicated catalytic ozonation with the prepared catalysts significantly enhanced performance of pollutants removal and the treated wastewater was more biodegradable and less toxic than that in ozonation alone. On the basis of positive effect of higher pH and significant inhibition of radical scavengers in catalytic ozonation, it was deduced that the enhancement of catalytic activity was responsible for generating hydroxyl radicals and the possible reaction pathway was proposed. Moreover, the prepared catalysts showed superior stability and most of toxic and refractory compounds were eliminated at successive catalytic ozonation runs. Thus, the process with economical, efficient and sustainable advantages was beneficial to engineering application.

  12. Structure-based engineering increased the catalytic turnover rate of a novel phenazine prenyltransferase.

    Directory of Open Access Journals (Sweden)

    Georg Zocher

    Full Text Available Prenyltransferases (PTs catalyze the regioselective transfer of prenyl moieties onto aromatic substrates in biosynthetic pathways of microbial secondary metabolites. Therefore, these enzymes contribute to the chemical diversity of natural products. Prenylation is frequently essential for the pharmacological properties of these metabolites, including their antibiotic and antitumor activities. Recently, the first phenazine PTs, termed EpzP and PpzP, were isolated and biochemically characterized. The two enzymes play a central role in the biosynthesis of endophenazines by catalyzing the regiospecific prenylation of 5,10-dihydrophenazine-1-carboxylic acid (dhPCA in the secondary metabolism of two different Streptomyces strains. Here we report crystal structures of EpzP in its unliganded state as well as bound to S-thiolodiphosphate (SPP, thus defining the first three-dimensional structures for any phenazine PT. A model of a ternary complex resulted from in silico modeling of dhPCA and site-directed mutagenesis. The structural analysis provides detailed insight into the likely mechanism of phenazine prenylation. The catalytic mechanism suggested by the structure identifies amino acids that are required for catalysis. Inspection of the structures and the model of the ternary complex furthermore allowed us to rationally engineer EpzP variants with up to 14-fold higher catalytic reaction rate compared to the wild-type enzyme. This study therefore provides a solid foundation for additional enzyme modifications that should result in efficient, tailor-made biocatalysts for phenazines production.

  13. Catalytic performance and molecular dynamic simulation of immobilized CC bond hydrolase based on carbon nanotube matrix.

    Science.gov (United States)

    Zhou, Hao; Qu, Yuanyuan; Kong, Chunlei; Li, Duanxing; Shen, E; Ma, Qiao; Zhang, Xuwang; Wang, Jingwei; Zhou, Jiti

    2014-04-01

    Carbon nanotube (CNT) has been proved to be a kind of novel support for enzyme immobilization. In this study, we tried to find the relationship between conformation and catalytic performance of immobilized enzyme. Two CC bond hydrolases BphD and MfphA were immobilized on CNTs (SWCNT and MWCNT) via physical adsorption and covalent attachment. Among the conjugates, the immobilized BphD on chemically functionalized SWCNT (BphD-CSWCNT) retained the highest catalytic efficiency (kcat/Km value) compared to free BphD (92.9%). On the other hand, when MfphA bound to pristine SWCNT (MfphA-SWCNT), it was completely inactive. Time-resolved fluorescence spectrum indicated the formation of static ground complexes during the immobilization processes. Circular dichroism (CD) showed that the secondary structures of immobilized enzymes changed in varying degrees. In order to investigate the inhibition mechanism of MfphA by SWCNT, molecular dynamics simulation was employed to analyze the adsorption process, binding sites and time evolution of substrate tunnels. The results showed that the preferred binding sites (Trp201 and Met81) of MfphA for SWCNT blocked the main substrate access tunnel, thus making the enzyme inactive. The "tunnel-block" should be a novel possible inhibition mechanism for enzyme-nanotube conjugate.

  14. Emergent Catalytic Behavior of Self-Assembled Low Molecular Weight Peptide-Based Aggregates and Hydrogels.

    Science.gov (United States)

    Tena-Solsona, Marta; Nanda, Jayanta; Díaz-Oltra, Santiago; Chotera, Agata; Ashkenasy, Gonen; Escuder, Beatriu

    2016-05-04

    We report a series of short peptides possessing the sequence (FE)n or (EF)n and bearing l-proline at their N-terminus that self-assemble into high aspect ratio aggregates and hydrogels. We show that these aggregates are able to catalyze the aldol reaction, whereas non-aggregated analogues are catalytically inactive. We have undertaken an analysis of the results, considering the accessibility of catalytic sites, pKa value shifts, and the presence of hydrophobic pockets. We conclude that the presence of hydrophobic regions is indeed relevant for substrate solubilization, but that the active site accessibility is the key factor for the observed differences in reaction rates. The results presented here provide an example of the emergence of a new chemical property caused by self-assembly, and support the relevant role played by self-assembled peptides in prebiotic scenarios. In this sense, the reported systems can be seen as primitive aldolase I mimics, and have been successfully tested for the synthesis of simple carbohydrate precursors.

  15. Investigating the Synthesis, Structure, and Catalytic Properties of Versatile Gold-Based Nanocatalvsts

    Science.gov (United States)

    Pretzer, Lori A.

    Transition metal nanomaterials are used to catalyze many chemical reactions, including those key to environmental, medicinal, and petrochemical fields. Improving their catalytic properties and lifetime would have significant economic and environmental rewards. Potentially expedient options to make such advancements are to alter the shape, size, or composition of transition metal nanocatalysts. This work investigates the relationships between structure and catalytic properties of synthesized Au, Pd-on-Au, and Au-enzyme model transition metal nanocatalysts. Au and Pd-on-Au nanomaterials were studied due to their wide-spread application and structure-dependent electronic and geometric properties. The goal of this thesis is to contribute design procedures and synthesis methods that enable the preparation of more efficient transition metal nanocatalysts. The influence of the size and composition of Pd-on-Au nanoparticles (NPs) was systematically investigated and each was found to affect the catalyst's surface structure and catalytic properties. The catalytic hydrodechlorination of trichloroethene and reduction of 4-nitrophenol by Pd-on-Au nanoparticles were investigated as these reactions are useful for environmental and pharmaceutical synthesis applications, respectively. Structural characterization revealed that the dispersion and oxidation state of surface Pd atoms are controlled by the Au particle size and concentration of Pd. These structural changes are correlated with observed Pd-on-Au NP activities for both probe reactions, providing new insight into the structure-activity relationships of bimetallic nanocatalysts. Using the structure-dependent electronic properties of Au NPs, a new type of light-triggered biocatalyst was prepared and used to remotely control a model biochemical reaction. This biocatalyst consists of a model thermophilic glucokinase enzyme covalently attached to the surface of Au nanorods. The rod-like shape of the Au nanoparticles made the

  16. Effect of aluminum modification on catalytic properties of PtSn-based catalysts supported on SBA-15 for propane dehydrogenation

    Institute of Scientific and Technical Information of China (English)

    Yongzheng Duan; Yuming Zhou; Yiwei Zhang; Xiaoli Sheng; Shijian Zhou; Zewu Zhang

    2012-01-01

    The catalytic properties of PtSn-based catalysts supported on siliceous SBA-15 and Al-modified SBA-15,such as Al-incorporated SBA-15 (AlSBA-15) and alumina-modified SBA-15 (Al2O3/SBA-15),for propane dehydrogenation were investigated.Al2O3/SBA-15 was prepared either by an impregnation method using aluminum nitrate aqueous solution,or by the treatment of SBA-15 with a Al(OC3H7)3 solution in anhydrous toluene.N2-physisorption,FT-IR spectroscopy,solid-state 27Al MAS NMR spectroscopy,hydrogen chemisorption,XRF,NH3 temperature-programmed desorption,X-ray photoelectron spectroscopy and TPO were used to characterize these samples.Among these catalysts,the PtSn-based catalyst supported on Al2O3/SBA-15,which was grafted with Al(OC3H7)3,exhibited the best catalytic performance in terms of activity and stability The possible reason was due to the high Pt metal dispersion and/or the strong interactions among Pt,Sn,and the support.

  17. Study of the catalytic layer in polybenzimidazole-based high temperature PEMFC: effect of platinum content on the carbon support

    Energy Technology Data Exchange (ETDEWEB)

    Lobato, J.; Canizares, P.; Rodrigo, M.A.; Linares, J.J.; Ubeda, D.; Pinar, F.J. [Chemical Engineering Department, University of Castilla-La Mancha, Ciudad Real (Spain)

    2010-04-15

    In this work, the effect of platinum percentage on the carbon support of commercial catalyst for electrodes to be used in a Polybenzimidazole (PBI)-based PEMFC has been studied. Three percentages were studied (20, 40 and 60%). In all cases, the same quantity of PBI in the catalyst layer was added, which is required as a 'binder'. From Hg porosimetry analyses, pore size distribution, porosity, mean pore size and tortuosity of all electrodes were obtained. The amount of mesopores gets larger as the platinum percentage in the catalytic layer decreases, which reduces the overall porosity and the mean pore size and increases the tortuosity. The electrochemical characterisation was performed by voltamperometric studies, assessing the effective electrochemical surface area (ESA) of the electrodes, by impedance spectroscopy (IS), determining the polarisation resistance, and by the corresponding fuel cell measurements. The best results were obtained for the electrodes with a content of 40% Pt on carbon, as a result of an adequate combination of catalytic activity and mass transfer characteristics of the electrode. It has been demonstrated that the temperature favours the fuel cell performance, and the humidification does not have remarkable effects on the performance of a PBI-based polymer electrolyte membrane fuel cell (PEMFC). (Abstract Copyright [2010], Wiley Periodicals, Inc.)

  18. 基于对生物质焦油催化裂解的催化材料%Catalytic Materials Based on the Catalytic Cracking of Biomass Tar

    Institute of Scientific and Technical Information of China (English)

    陈雨亭; 王燕刚; 秦恒飞; 康诗飞; 李溪; 崔立峰

    2015-01-01

    Biomass energy, as a renewable energy, has attracted more and more attention. Biomass energy has an important significance for the future sustainable development of the world's energy. Biomass gasification technology is one of the most effective biomass energy conversion methods which can well translate the biomass into the efficient fuel gas. However, the development of this technology is limited by biomass tar which is produced during the gasification process. The removal methods of tar in the biomass gasification process were summarized, and four kinds of catalysts applied in the process of catalytic cracking were mainly introduced and further classifies discussion was made on the composition, catalytic mechanism and modified optimization way of four kinds of catalysts, and the effects of different cracking condition on the catalytic result. The results showed an outlook for the development of biomass gasification technology and proposes future research emphasis of catalytic cracking.%生物质能作为一种可再生能源,越来越受到广泛关注。生物质能对未来世界能源的可持续发展具有重要意义。生物质能具有多种转化途径,其中生物质气化技术能有效将其转化为高效燃气,而生物质焦油是限制生物质气化技术发展的关键所在,本文针对生物质气化过程中的核心技术焦油去除的方法做了全面总结。重点介绍了催化裂解过程中应用的4种催化剂,并对4种催化剂的组成、催化机理以及催化剂的改性优化方式以及不同裂解条件对催化效果的影响进行了分类讨论。最后展望了生物质气化技术的发展前景,提出了未来催化裂解的研究重点。

  19. Click on silica: systematic immobilization of Co(II) Schiff bases to the mesoporous silica via click reaction and their catalytic activity for aerobic oxidation of alcohols.

    Science.gov (United States)

    Rana, Bharat S; Jain, Suman L; Singh, Bhawan; Bhaumik, Asim; Sain, Bir; Sinha, Anil K

    2010-09-07

    The systematic immobilization of cobalt(II) Schiff base complexes on SBA-15 mesoporous silica via copper catalyzed [3 + 2] azide-alkyne cycloaddition (CuAAC) "click reaction" involving either step-wise synthesis of silica-bound Schiff base ligand followed by its subsequent complexation with cobalt ions, or by the direct immobilization of preformed Co(II) Schiff base complex to the silica support is described. The catalytic activity of the prepared complexes was studied for the oxidation of alcohols to carbonyl compounds using molecular oxygen as oxidant. The immobilized complexes were recycled for several runs without loss in catalytic activity and no leaching was observed during this course.

  20. Catalytic wet air oxidation of coke-plant wastewater on ruthenium-based eggshell catalysts in a bubbling bed reactor.

    Science.gov (United States)

    Yang, M; Sun, Y; Xu, A H; Lu, X Y; Du, H Z; Sun, C L; Li, C

    2007-07-01

    Catalytic wet air of coke-plant wastewater was studied in a bubbling bed reactor. Two types of supported Ru-based catalysts, eggshell and uniform catalysts, were employed. Compared with the results in the wet air oxidation of coke-plant wastewater, supported Ru uniform catalysts showed high activity for chemical oxygen demand (COD) and ammonia/ammonium compounds (NH3-N) removal at temperature of 250 degrees C and pressure of 4.8 MPa, and it has been demonstrated that the catalytic activity of uniform catalyst depended strongly on the distribution of active sites of Ru on catalyst. Compared to the corresponding uniform catalysts with the same Ru loading (0.25 wt.% and 0.1 wt.%, respectively), the eggshell catalysts showed higher activities for CODcr removal and much higher activities for NH3-N degradation. The high activity of eggshell catalyst for treatment of coke-plant wastewater can be attributed to the higher density of active Ru sites in the shell layer than that of the corresponding uniform catalyst with the same Ru loading. It has been also evidenced that the active Ru sites in the internal core of uniform catalyst have very little or no contribution to CODcr and NH3-N removal in the total oxidation of coke-plant wastewater.

  1. Structured Perovskite-Based Catalysts and Their Application as Three-Way Catalytic Converters—A Review

    Directory of Open Access Journals (Sweden)

    Sylvain Keav

    2014-07-01

    Full Text Available Automotive Three-Way Catalysts (TWC were introduced more than 40 years ago. Despite that, the development of a sustainable TWC still remains a critical research topic owing to the increasingly stringent emission regulations together with the price and scarcity of precious metals. Among other material classes, perovskite-type oxides are known to be valuable alternatives to conventionally used TWC compositions and have demonstrated to be suitable for a wide range of automotive applications, ranging from TWC to Diesel Oxidation Catalysts (DOC, from NOx Storage Reduction catalysts (NSR to soot combustion catalysts. The interest in these catalysts has been revitalized in the past ten years by the introduction of the concept of catalyst regenerability of perovskite-based TWC, which is in principle well applicable to other catalytic processes as well, and by the possibility to reduce the amounts of critical elements, such as precious metals without seriously lowering the catalytic performance. The aim of this review is to show that perovskite-type oxides have the potential to fulfil the requirements (high activity, stability, and possibility to be included into structured catalysts for implementation in TWC.

  2. The Significance of Lewis Acid Sites for the Selective Catalytic Reduction of Nitric Oxide on Vanadium-Based Catalysts.

    Science.gov (United States)

    Marberger, Adrian; Ferri, Davide; Elsener, Martin; Kröcher, Oliver

    2016-09-19

    The long debated reaction mechanisms of the selective catalytic reduction (SCR) of nitric oxide with ammonia (NH3 ) on vanadium-based catalysts rely on the involvement of Brønsted or Lewis acid sites. This issue has been clearly elucidated using a combination of transient perturbations of the catalyst environment with operando time-resolved spectroscopy to obtain unique molecular level insights. Nitric oxide reacts predominantly with NH3 coordinated to Lewis sites on vanadia on tungsta-titania (V2 O5 -WO3 -TiO2 ), while Brønsted sites are not involved in the catalytic cycle. The Lewis site is a mono-oxo vanadyl group that reduces only in the presence of both nitric oxide and NH3 . We were also able to verify the formation of the nitrosamide (NH2 NO) intermediate, which forms in tandem with vanadium reduction, and thus the entire mechanism of SCR. Our experimental approach, demonstrated in the specific case of SCR, promises to progress the understanding of chemical reactions of technological relevance.

  3. Research on Integration of an Automotive Exhaust-Based Thermoelectric Generator and a Three-Way Catalytic Converter

    Science.gov (United States)

    Deng, Y. D.; Chen, Y. L.; Chen, S.; Xianyu, W. D.; Su, C. Q.

    2015-06-01

    A key research topic related to thermoelectric generators (TEGs) for automotive applications is to improve their compatibility with the original vehicle exhaust system, which determines the quality of the exhaust gas treatment and the realization of energy conservation and emission reduction. A new TEG integrated with a three-way catalytic converter (CTEG) by reshaping the converter as the heat exchanger is proposed. A heat-flux coupling simulation model of the integrated TEG is established at the light-off stage of the original three-way catalytic converter (TWC). Temperature distribution maps of the integrated heat exchanger, thermoelectric modules, and cooling-water tank are obtained to present the process of energy flow among the parts of the CTEG. Based on the simulation results, the output power of the CTEG is calculated by a mathematical model. A minimum output power of 31.93 W can be obtained by conversion when the TWC starts working at steady conditions. Theoretically, this case study demonstrates the great potential for use of CTEGs in vehicles.

  4. Noble metal-based bimetallic nanoparticles: the effect of the structure on the optical, catalytic and photocatalytic properties.

    Science.gov (United States)

    Zaleska-Medynska, Adriana; Marchelek, Martyna; Diak, Magdalena; Grabowska, Ewelina

    2016-03-01

    Nanoparticles composed of two different metal elements show novel electronic, optical, catalytic or photocatalytic properties from monometallic nanoparticles. Bimetallic nanoparticles could show not only the combination of the properties related to the presence of two individual metals, but also new properties due to a synergy between two metals. The structure of bimetallic nanoparticles can be oriented in random alloy, alloy with an intermetallic compound, cluster-in-cluster or core-shell structures and is strictly dependent on the relative strengths of metal-metal bond, surface energies of bulk elements, relative atomic sizes, preparation method and conditions, etc. In this review, selected properties, such as structure, optical, catalytic and photocatalytic of noble metals-based bimetallic nanoparticles, are discussed together with preparation routes. The effects of preparation method conditions as well as metal properties on the final structure of bimetallic nanoparticles (from alloy to core-shell structure) are followed. The role of bimetallic nanoparticles in heterogeneous catalysis and photocatalysis are discussed. Furthermore, structure and optical characteristics of bimetallic nanoparticles are described in relation to the some features of monometallic NPs. Such a complex approach allows to systematize knowledge and to identify the future direction of research.

  5. A Broad Spectrum Catalytic System for Removal of Toxic Organics from Water by Deep Oxidation - Final Report

    Energy Technology Data Exchange (ETDEWEB)

    Sen, Ayusman

    2000-12-01

    A most pressing need for the DOE environmental management program is the removal of toxic organic compounds present in groundwater and soil at specific DOE sites. While several remediation procedures have been proposed, they suffer from one or more drawbacks. The objective of the present research was to develop new catalytic procedures for the removal of toxic organic compounds from the environment through their deep oxidation to harmless products. In water, metallic palladium was found to catalyze the deep oxidation of a wide variety of toxic organic compounds by dioxygen at 80-90 C in the presence of carbon monoxide or dihydrogen. Several classes of organic compounds were examined: benzene, phenol and substituted phenols, nitro and halo organics, organophosphorus, and organosulfur compounds. In every case, deep oxidation to carbon monoxide, carbon dioxide, and water occurred in high yields, resulting in up to several hundred turnovers over a 24 hour period. For substrates susceptible to hydrogenation, the conversions were generally high with dihydrogen than with carbon monoxide. It is clear from the results obtained that we have discovered an exceptionally versatile catalytic system for the deep oxidation of toxic organic compounds in water. This system possesses several attractive features not found simultaneously in other reported systems. These are (a) the ability to directly utilize dioxygen as the oxidant, (b) the ability to carry out the deep oxidation of a particularly wide range of functional organics, and (c) the ease of recovery of the catalyst by simple filtration.

  6. Catalytic wet-air oxidation of a chemical plant wastewater over platinum-based catalysts.

    Science.gov (United States)

    Cybulski, Andrzej; Trawczyński, Janusz

    2006-01-01

    Catalytic wet-air oxidation (CWAO) of wastewater (chemical oxygen demand [COD] = 1800 mg O2/dm3) from a fine chemicals plant was investigated in a fixed-bed reactor at T = 393-473 K under total pressure of 5.0 or 8.0 MPa. Catalysts containing 0.3% wt. of platinum deposited on two supports, mixed silica-titania (SM1) and carbon black composites (CBC) were used. The CBC-supported catalyst appeared to be more active than the SM1-supported one. A slow decrease of activity of the platinum on SM1 (Pt-SM1) during the long-term operation is attributed to recrystallization of titania and leaching of a support component, while the Pt-CBC catalyst is deteriorated, owing to combustion of the support component. The power-law-kinetic equations were used to describe the rate of COD removal at CWAO over the catalysts. The kinetic parameters of COD reduction for the wastewater were determined and compared with the kinetic parameters describing phenol oxidation over the same catalysts. Rates of COD removal for the wastewater were found higher than those for phenol oxidation over the same catalysts and under identical operating conditions.

  7. Hydrogen production by catalytic decomposition of methane using a Fe-based catalyst in a fluidized bed reactor

    Institute of Scientific and Technical Information of China (English)

    D.Torres; S.de Llobet; J.L.Pinilla; M.J.Lázaro; I.Suelves; R.Moliner

    2012-01-01

    Catalytic decomposition of methane using a Fe-based catalyst for hydrogen production has been studied in this work.A Fe/Al2O3 catalyst previously developed by our research group has been tested in a fluidized bed reactor (FBR).A parametric study of the effects of some process variables,including reaction temperature and space velocity,is undertaken.The operating conditions strongly affect the catalyst performance.Methane conversion was increased by increasing the temperature and lowering the space velocity.Using temperatures between 700 and 900 ℃ and space velocities between 3 and 6 LN/(gcat·h),a methane conversion in the range of 25%-40% for the gas exiting the reactor could be obtained during a 6 h run.In addition,carbon was deposited in the form of nanofilaments (chain like nanofibers and multiwall nanotubes) with similar properties to those obtained in a fixed bed reactor.

  8. Flow Injection Determination of Oxalate Based on Its Catalytic Effect on the Oxidation of p-Chloride Aniline by Dichromate

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    In a sulfuric acid medium, oxalate exhibits a strong catalytic effect on the oxidation of p-chloride aniline (ClBN) by dichromate, and the red oxidation product of ClBN has a maximum absorbancy at 520 nm. Based on this founding, a new FI method for determining oxalate was developed. A calibration curve of oxalate in the range of 0. 40-17.0 tg/mL was obtained. The detection limit was 0. 10 μg/mL. Sampling rate was 103-samples/h. The possible interference by the co-existing substances or ions was examined. This new method was applied to the determination of micro amounts of oxalate in real samples with satisfactory results.

  9. Dendritic structure DNA for specific metal ion biosensor based on catalytic hairpin assembly and a sensitive synergistic amplification strategy.

    Science.gov (United States)

    Zhao, Jianmin; Jing, Pei; Xue, Shuyan; Xu, Wenju

    2017-01-15

    In this work, a sensitive electrochemical biosensing to Pb(2+) was proposed based on the high specificity of DNAzymes to Pb(2+). The response signal was efficiently amplified by the catalytic hairpin assembly induced by strand replacement reaction and the formation of dendritic structure DNA (DSDNA) by layer-by-layer assembly. Firstly, in the presence of Pb(2+), the substrate strand (S1) of the Pb(2+)-specific DNAzymes was specifically cleaved by Pb(2+). Secondly, one of the two fragments (rS1) introduced into the electrode surface was hybridized with a hairpin DNA (H1) and further replaced by another hairpin DNA (H2) by the hybridization reaction of H1 with H2. The released rS1 then induced the next hybridization with H1. After repeated cycles, the catalytic recycling assembly of H2 with H1 was completed. Thirdly, two bioconjugates of Pt@Pd nanocages (Pt@PdNCs) labeled with DNA S3/S4 and electroactive toluidine blue (Tb) (Tb-S3-Pt@PdNCs and Tb-S4-Pt@PdNCs) were captured onto the resultant electrode surface through the hybridization of S3 and H2, S3 and S4, resulting in the formation of DSDNA triggered by layer-by-layer assembly. This formed DSDNA greatly facilitated the immobilization of manganese(III) meso-tetrakis (4-N-methylpyridiniumyl)-porphyrin (MnTMPyP) as mimicking enzyme. Under the synergistic catalysis of Pt@PdNCs and MnTMPyP to H2O2 reduction, the effective signal amplification of the developed Pb(2+) biosensor was achieved. As a result, the sensitive detection of the proposed electrochemical strategy for Pb(2+) was greatly improved in the range of 0.1pM-200nM with a detection limit of 0.033pM.

  10. 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.

  11. Low temperature selective catalytic reduction of NOx with NH3 over Mn-based catalyst: A review

    OpenAIRE

    TsungYu Lee; Hsunling Bai

    2016-01-01

    The removals of NOx by catalytic technology at low temperatures (100–300 °C) for industrial flue gas treatment have received increasing attention. However, the development of low temperature catalysts for selective catalytic reduction (SCR) of NOx with ammonia is still a challenge especially in the presence of SO2. The current status of using Mn-based catalysts for low temperature SCR of NOx with ammonia (NH3-SCR) is reviewed. Reaction mechanisms and effects of operating factors on low temper...

  12. Synthesis, characterization, crystal structure determination and catalytic activity in epoxidation reaction of two new oxidovanadium(IV) Schiff base complexes

    Science.gov (United States)

    Tahmasebi, Vida; Grivani, Gholamhossein; Bruno, Giuseppe

    2016-11-01

    The five coordinated vanadium(IV) Schiff base complexes of VOL1 (1) and VOL2 (2), HL1 = 2-{(E)-[2-bromoethyl)imino]methyl}-2- naphthol, HL2 = 2-{(E)-[2-chloroethyl)imino]methyl}-2- naphthol, have been synthesized and they were characterized by using single-crystal X-ray crystallography, elemental analysis (CHN) and FT-IR spectroscopy. Crystal structure determination of these complexes shows that the Schiff base ligands (L1 and L2) act as bidentate ligands with two phenolato oxygen atoms and two imine nitrogen atoms in the trans geometry. The coordination geometry around the vanadium(IV) is distorted square pyramidal in which vanadium(IV) is coordinated by two nitrogen and two oxygen atoms of two independent ligands in the basal plane and by one oxygen atom in the apical position. The catalytic activity of the Schiff base complexes of 1 and 2 in the epoxidation of alkenes were investigated using different reaction parameters such as solvent effect, oxidant, alkene/oxidant ratio and the catalyst amount. The results showed that in the presence of TBHP as oxidant in 1: 4 and 1:3 ratio of the cyclooctene/oxidant ratio, high epoxide yield was obtained for 1 (76%) and 2 (80%) with TON(= mole of substrate/mole of catalyst) of 27 and 28.5, respectively, in epoxidation of cyclooctene.

  13. Adsorptive removal of lead and cadmium ions using Cross -linked CMC Schiff base: Isotherm, Kinetics and Catalytic Activity

    Directory of Open Access Journals (Sweden)

    P. Moganavally

    2016-03-01

    Full Text Available Water plays a vital role to human and other living organisms. Due to the effluent coming from chemical industries, the industrial activity, contamination of ground water level is goes on increasing nowadays. Therefore, there is a need to develop technologies that can remove toxic pollutants in wastewater. Hence the cross linked Carboxymethyl chitosan(CMC/ 2,3-dimethoxy Benzaldehyde Schiff base complex has been synthesized and characterized by using FT-IR and SEM analysis. All these results revealed that cross linked Schiff base has formed with high adsorption capacity. The prepared effective adsorbent used for the removal of heavy metals like lead (II and cadmium (II ions from aqueous solution and the adsorption data follow the Freundlich model, which follows pseudo first order kinetics. Effect of various parameters like solution pH, adsorbent dose and contact time for the removal of heavy metals has been studied. The synthesized sample undergoes catalytic oxidation process significantly at 24 hrs. The results showed that cross linked Schiff base is an effective, eco-friendly, low-cost adsorbent.

  14. Direct catalytic transformation of carbohydrates into 5-ethoxymethylfurfural with acid–base bifunctional hybrid nanospheres

    DEFF Research Database (Denmark)

    Li, Hu; Khokarale, Santosh Govind; Kotni, Ramakrishna;

    2014-01-01

    carbohydrates. A high EMF yield of 76.6%, 58.5%, 42.4%, and 36.5% could be achieved, when fructose, inulin, sorbose, and sucrose were used as starting materials, respectively. Although, the acid–base bifunctional nanocatalysts were inert for synthesis of EMF from glucose based carbohydrates, ethyl...

  15. Preparation and photo-catalytic activity of TiO2-coated medical stone-based porous ceramics

    Science.gov (United States)

    Gao, Ru-qin; Hou, Xin-mei

    2013-06-01

    Medical stone-based porous ceramics as a carrier were prepared by ultra-fine grinding and low-temperature sintering method. Nano-TiO2 thin films were loaded on the carrier by chemical liquid deposition method using titanium tetrachloride as a precursor. The micro-morphology and microstructure of the synthesized samples were characterized using X-ray diffraction, scanning electron microscopy with energy dispersive spectrometry, and mercury injection method. The photo-catalytic activity of the TiO2 thin films was investigated by degrading formaldehyde. The main crystalline phase in the TiO2 thin films calcined at 550°C is anatase with the average particle size about 10 nm. The specific surface area of the carrier-coated nano-TiO2 increases from 3.68 to 5.32 m2/g. The formaldehyde removal rate of the TiO2/medical stone-based porous ceramics irradiated under an ultraviolet lamp for 120 min reaches 85.6%.

  16. Enumerating pathways of proton abstraction based on a spatial and electrostatic analysis of residues in the catalytic site.

    Directory of Open Access Journals (Sweden)

    Sandeep Chakraborty

    Full Text Available The pathways of proton abstraction (PA, a key aspect of most catalytic reactions, is often controversial and highly debated. Ultrahigh-resolution diffraction studies, molecular dynamics, quantum mechanics and molecular mechanic simulations are often adopted to gain insights in the PA mechanisms in enzymes. These methods require expertise and effort to setup and can be computationally intensive. We present a push button methodology--Proton abstraction Simulation (PRISM--to enumerate the possible pathways of PA in a protein with known 3D structure based on the spatial and electrostatic properties of residues in the proximity of a given nucleophilic residue. Proton movements are evaluated in the vicinity of this nucleophilic residue based on distances, potential differences, spatial channels and characteristics of the individual residues (polarity, acidic, basic, etc. Modulating these parameters eliminates their empirical nature and also might reveal pathways that originate from conformational changes. We have validated our method using serine proteases and concurred with the dichotomy in PA in Class A β-lactamases, both of which are hydrolases. The PA mechanism in a transferase has also been corroborated. The source code is made available at www.sanchak.com/prism.

  17. Catalytic Asymmetric Carbon-Carbon Forming Reactions Catalyzed Chiral Schiff Base-Metal Complexes

    Institute of Scientific and Technical Information of China (English)

    Takanori; Tanaka; Masahiko; Hayashi

    2007-01-01

    1 Results In 1991, we disclosed the novel asymmetric catalysts prepared from chiral Schiff base and titanium alkoxide in the reaction of asymmetric silylcyanation of aldehydes (eq.1)[1]. Since our first report, chiral Schiff base-metal complex was proven to be efficient in a variety of asymmetric reactions. We reported the first example of enantioselective addition of diketene to aldehydes promoted by chiral Schiff base-titanium alkoxide complexes (eq.2)[2]. The products of this reaction have been cove...

  18. Synthesis of copper/nickel nanoparticles using newly synthesized Schiff-base metals complexes and their cytotoxicity/catalytic activities.

    Science.gov (United States)

    Aazam, Elham S; El-Said, Waleed Ahmed

    2014-12-01

    Transition metal complexes compounds with Schiff bases ligand representing an important class of compounds that could be used to develop new metal-based anticancer agents and as precursors of metal NPs. Herein, 2,3-bis-[(3-ethoxy-2-hydroxybenzylidene)amino]but-2-enedinitrile Schiff base ligand and its corresponding copper/nickel complexes were synthesized. Also, we reported a facile and rapid method for synthesis nickel/copper nanoparticles based on thermal reduction of their complexes. Free ligand, its metal complexes and metals nanoparticles have been characterized based on elemental analysis, transmission electron microscopy, powder X-ray diffraction, magnetic measurements and by various spectroscopic (UV-vis, FT-IR, (1)H NMR, GC-MS) techniques. Additionally, the in vitro cytotoxic activity of free ligand and its complexes compounds were assessed against two cancer cell lines (HeLa and MCF-7 cells)and one healthy cell line (HEK293 cell). The copper complex was found to be active against these cancer cell lines at very low LD50 than the free ligand, while nickel complex did not show any anticancer activity against these cell lines. Also, the antibacterial activity of as-prepared copper nanoparticles were screened against Escherichia coli, which demonstrated minimum inhibitory concentration and minimum bactericidal concentration values lower than those values of the commercial Cu NPs as well as the previous reported values. Moreover, the synthesized nickel nanoparticles demonstrated remarkable catalytic performance toward hydrogenation of nitrobenzene that producing clean aniline with high selectivity (98%). This reactivity could be attributed to the high degree of dispersion of Ni nanoparticles.

  19. Unsteady catalytic processes and sorption-catalytic technologies

    Energy Technology Data Exchange (ETDEWEB)

    Zagoruiko, A N [G.K. Boreskov Institute of Catalysis, Siberian Branch of the Russian Academy of Sciences, Novosibirsk (Russian Federation)

    2007-07-31

    Catalytic processes that occur under conditions of the targeted unsteady state of the catalyst are considered. The highest efficiency of catalytic processes was found to be ensured by a controlled combination of thermal non-stationarity and unsteady composition of the catalyst surface. The processes based on this principle are analysed, in particular, catalytic selective reduction of nitrogen oxides, deep oxidation of volatile organic impurities, production of sulfur by the Claus process and by hydrogen sulfide decomposition, oxidation of sulfur dioxide, methane steam reforming and anaerobic combustion, selective oxidation of hydrocarbons, etc.

  20. Immobilization of cobalt(II) Schiff base complexes on polystyrene resin and a study of their catalytic activity for the aerobic oxidation of alcohols.

    Science.gov (United States)

    Jain, Suman; Reiser, Oliver

    2008-01-01

    The copper-catalyzed [3+2] azide-alkyne cycloaddition and the Staudinger ligation are readily applicable and highly efficient for the immobilization of cobalt Schiff base complexes onto polystyrene resins. Stepwise synthesis of polymer-bound Schiff bases followed by their subsequent complexation with metal ions were successfully carried out. Direct covalent attachment of preformed homogeneous cobalt Schiff base complexes to the resins was also possible. The catalytic efficiency of the so-prepared polystyrene-bound cobalt Schiff bases was studied for the oxidation of alcohols to carbonyl compounds using molecular oxygen as oxidant. The immobilized complexes were highly efficient and even more reactive than the corresponding homogenous analogues, thus affording better yields of oxidized products within shorter reaction times. The supported catalysts could easily be recovered from the reaction mixture by simple filtration and reused for subsequent experiments with consistent catalytic activity.

  1. Mononuclear Ru(III) Schiff base complexes: Synthesis, spectral, redox, catalytic and biological activity studies

    Science.gov (United States)

    Priya, N. Padma; Arunachalam, S.; Manimaran, A.; Muthupriya, D.; Jayabalakrishnan, C.

    2009-04-01

    An octahedral ruthenium(III) Schiff base complexes of the type [RuX(EPh 3)(L)] (where, X = Cl/Br; E = As/P; L = dianion of the Schiff bases derived from acetoacetanilide with o-phenylenediamine and salicylaldehyde/ o-hydroxyacetophenone/ o-vanillin/2-hydroxy-1-naphthaldehyde) have been synthesized from the reactions of equimolar reactions of [RuX 3(EPh 3) 3] and Schiff bases in benzene. The new Ru(III) Schiff base complexes have been characterized by elemental analyses, FT-IR, electronic, 1H NMR and 13C NMR spectra, EPR spectral studies, powder X-ray diffraction (XRD) and electrochemical studies. The new complexes were found to be effective catalysts for aryl-aryl coupling and the oxidation of alcohols into their corresponding carbonyl compounds, respectively, using molecular oxygen atmosphere at ambient temperature. Further, the new Ru(III) Schiff base complexes were screened for their antibacterial activity against Pseudomonas aeruginosa, Vibrio cholera, Salomonella typhi and Staphylococcus aureaus.

  2. Colorimetric detection of trace copper ions based on catalytic leaching of silver-coated gold nanoparticles.

    Science.gov (United States)

    Lou, Tingting; Chen, Lingxin; Chen, Zhaopeng; Wang, Yunqing; Chen, Ling; Li, Jinhua

    2011-11-01

    A colorimetric, label-free, and nonaggregation-based silver coated gold nanoparticles (Ag/Au NPs) probe has been developed for detection of trace Cu(2+) in aqueous solution, based on the fact that Cu(2+) can accelerate the leaching rate of Ag/Au NPs by thiosulfate (S(2)O(3)(2-)). The leaching of Ag/Au NPs would lead to dramatic decrease in the surface plasmon resonance (SPR) absorption as the size of Ag/Au NPs decreased. This colorimetric strategy based on size-dependence of nanoparticles during their leaching process provided a highly sensitive (1.0 nM) and selective detection toward Cu(2+), with a wide linear detection range (5-800 nM) over nearly 3 orders of magnitude. The cost-effective probe allows rapid and sensitive detection of trace Cu(2+) ions in water samples, indicating its potential applicability for the determination of copper in real samples.

  3. Lanthanide-Based Metal Organic Frameworks: Synthetic Strategies and Catalytic Applications

    NARCIS (Netherlands)

    C. Pagis; M. Ferbinteanu; G. Rothenberg; S. Grecea

    2016-01-01

    This short critical review outlines the main synthetic strategies used in the designed synthesis of lanthanide-based metal organic frameworks (Ln-MOFs). It explains the impact of the choice of organic linker on the final network topology, and it highlights the applications of Ln-MOFs in the catalysi

  4. Synthesis, structural characterization, catalytic, thermal and electrochemical investigations of bidentate Schiff base ligand and its metal complexes.

    Science.gov (United States)

    Dolaz, Mustafa; McKee, Vickie; Uruş, Serhan; Demir, Necmettin; Sabik, Ali E; Gölcü, Ayşegül; Tümer, Mehmet

    2010-07-01

    In this study, we prepared the Schiff base ligand (L) and its Cu(II), Co(II) and Ni(II) complexes. The compounds were characterized by the analytical and spectroscopic methods. The ligand (L) behaves as a bidentate ligand and coordinates to the metal ions via the nitrogen atoms. The complexes have the mononuclear structures. The analytical and spectroscopic results indicated that the chloride ions coordinate to the metal ions. The complexes have the general formulae [M(L)(Cl)(2)] (M: Cu(II), Co(II) and Ni(II) metal ions). Electrochemical properties were investigated as ligand and metal centres in the different solvents and at the scan rates, respectively. The thermal properties of the metal complexes were studied in the N(2) atmosphere. We investigated the improved catalytic activity of the Cu(II), Co(II) and Ni(II) complexes on the cyclohexane as a substrate. Obtained data showed that the best catalyst is the Cu(II) complex. The single crystal of the ligand (L) was obtained from CH(3)CN solution. There is a C-H...N H-bond linking the molecules into chains (C6)...N(2) 3.4415(18)A under symmetry operation (x+1,y,z) as well as pi-pi stacking on the outside of the "V" shape--nothing on the inside.

  5. Determining the storage, availability and reactivity of NH3 within Cu-Chabazite-based Ammonia Selective Catalytic Reduction systems.

    Science.gov (United States)

    Lezcano-Gonzalez, I; Deka, U; Arstad, B; Van Yperen-De Deyne, A; Hemelsoet, K; Waroquier, M; Van Speybroeck, V; Weckhuysen, B M; Beale, A M

    2014-01-28

    Three different types of NH3 species can be simultaneously present on Cu(2+)-exchanged CHA-type zeolites, commonly used in Ammonia Selective Catalytic Reduction (NH3-SCR) systems. These include ammonium ions (NH4(+)), formed on the Brønsted acid sites, [Cu(NH3)4](2+) complexes, resulting from NH3 coordination with the Cu(2+) Lewis sites, and NH3 adsorbed on extra-framework Al (EFAl) species, in contrast to the only two reacting NH3 species recently reported on Cu-SSZ-13 zeolite. The NH4(+) ions react very slowly in comparison to NH3 coordinated to Cu(2+) ions and are likely to contribute little to the standard NH3-SCR process, with the Brønsted groups acting primarily as NH3 storage sites. The availability/reactivity of NH4(+) ions can be however, notably improved by submitting the zeolite to repeated exchanges with Cu(2+), accompanied by a remarkable enhancement in the low temperature activity. Moreover, the presence of EFAl species could also have a positive influence on the reaction rate of the available NH4(+) ions. These results have important implications for NH3 storage and availability in Cu-Chabazite-based NH3-SCR systems.

  6. Catalytic transformation of persistent contaminants using a new composite material based on nanosized zero-valent iron.

    Science.gov (United States)

    Dror, Ishai; Jacov, Osnat Merom; Cortis, Andrea; Berkowitz, Brian

    2012-07-25

    A new composite material based on deposition of nanosized zerovalent iron (nZVI) particles and cyanocobalamine (vitamin B12) on a diatomite matrix is presented, for catalytic transformation of organic contaminants in water. Cyanocobalamine is known to be an effective electron mediator, having strong synergistic effects with nZVI for reductive dehalogenation reactions. This composite material also improves the reducing capacity of nZVI by preventing agglomeration of iron nanoparticles, thus increasing their active surface area. The porous structure of the diatomite matrix allows high hydraulic conductivity, which favors channeling of contaminated water to the reactive surface of the composite material resulting in faster rates of remediation. The composite material rapidly degrades or transforms completely a large spectrum of water contaminants, including halogenated solvents like TCE, PCE, and cis-DCE, pesticides like alachlor, atrazine and bromacyl, and common ions like nitrate, within minutes to hours. A field experiment where contaminated groundwater containing a mixture of industrial and agricultural persistent pollutants was conducted together with a set of laboratory experiments using individual contaminant solutions to analyze chemical transformations under controlled conditions.

  7. Development of advanced catalytic layer based on vertically aligned conductive polymer arrays for thin-film fuel cell electrodes

    Science.gov (United States)

    Jiang, Shangfeng; Yi, Baolian; Cao, Longsheng; Song, Wei; Zhao, Qing; Yu, Hongmei; Shao, Zhigang

    2016-10-01

    The degradation of carbon supports significantly influences the performance of proton exchange membrane fuel cells (PEMFCs), particularly in the cathode, which must be overcome for the wide application of fuel cells. In this study, advanced catalytic layer with electronic conductive polymer-polypyrrole (PPy) nanowire as ordered catalyst supports for PEMFCs is prepared. A platinum-palladium (PtPd) catalyst thin layer with whiskerette shapes forms along the long axis of the PPy nanowires. The resulting arrays are hot-pressed on both sides of a Nafion® membrane to construct a membrane electrode assembly (without additional ionomer). The ordered thin catalyst layer (approximately 1.1 μm) is applied in a single cell as the anode and the cathode without additional Nafion® ionomer. The single cell yields a maximum performance of 762.1 mW cm-2 with a low Pt loading (0.241 mg Pt cm-2, anode + cathode). The advanced catalyst layer indicates better mass transfer in high current density than that of commercial Pt/C-based electrode. The mass activity is 1.08-fold greater than that of DOE 2017 target. Thus, the as-prepared electrodes have the potential for application in fuel cells.

  8. Application of sludge-based carbonaceous materials in a hybrid water treatment process based on adsorption and catalytic wet air oxidation.

    Science.gov (United States)

    Julcour Lebigue, Carine; Andriantsiferana, Caroline; N'Guessan Krou; Ayral, Catherine; Mohamed, Elham; Wilhelm, Anne-Marie; Delmas, Henri; Le Coq, Laurence; Gerente, Claire; Smith, Karl M; Pullket, Suangusa; Fowler, Geoffrey D; Graham, Nigel J D

    2010-12-01

    This paper describes a preliminary evaluation of the performance of carbonaceous materials prepared from sewage sludges (SBCMs) in a hybrid water treatment process based on adsorption and catalytic wet air oxidation; phenol was used as the model pollutant. Three different sewage sludges were treated by either carbonisation or steam activation, and the physico-chemical properties of the resultant carbonaceous materials (e.g. hardness, BET surface area, ash and elemental content, surface chemistry) were evaluated and compared with a commercial reference activated carbon (PICA F22). The adsorption capacity for phenol of the SBCMs was greater than suggested by their BET surface area, but less than F22; a steam activated, dewatered raw sludge (SA_DRAW) had the greatest adsorption capacity of the SBCMs in the investigated range of concentrations (oxidation tests, the SBCMs demonstrated catalytic behaviour arising from their substrate adsorptivity and metal content. Recycling of SA_DRAW in successive oxidations led to significant structural attrition and a hardened SA_DRAW was evaluated, but found to be unsatisfactory during the oxidation step. In a combined adsorption-oxidation sequence, both the PICA carbon and a selected SBCM showed deterioration in phenol adsorption after oxidative regeneration, but a steady state performance was reached after 2 or 3 cycles.

  9. Fuzzy, copper-based multi-functional composite particles serving simultaneous catalytic and signal-enhancing roles

    Science.gov (United States)

    Li, Xiangming; Hu, Yingmo; An, Qi; Luan, Xinglong; Zhang, Qian; Zhang, Yihe

    2016-04-01

    Multifunctional plasmonic particles serving simultaneously as catalysts and label-free reporting agents are highly pursued due to their great potential in enhancing reaction operational efficiencies. Copper is an abundant and economic resource, and it possesses practical applicability in industries, but no dual-functional copper-based catalytic and self-reporting particles have been reported so far. This study proposes a facile strategy to prepare high-performance dual-functional copper-based composite particles that catalyze reactions and simultaneously serve as a SERS (surface enhanced Raman spectra) active, label-free reporting agent. Polyelectrolyte-modified reduced graphene oxide particles are used as the reactive precursors in the fabrication method. Upon adding Cu(NO3)2 solutions into the precursor dispersions, composite particles comprised by copper/copper oxide core and polyelectrolyte-graphene shell were facilely obtained under sonication. The as-prepared composite particles efficiently catalyzed the conversion of 4-nitrophenol to 4-aminophenol and simultaneously acted as the SERS-active substrate to give enhanced Raman spectra of the produced 4-aminophenol. Taking advantage of the assembling capabilities of polyelectrolyte shells, the composite particles could be further assembled onto a planar substrate to catalyze organic reactions, facilitating their application in various conditions. We expect this report to promote the fabrication and application of copper-based multifunctional particles.Multifunctional plasmonic particles serving simultaneously as catalysts and label-free reporting agents are highly pursued due to their great potential in enhancing reaction operational efficiencies. Copper is an abundant and economic resource, and it possesses practical applicability in industries, but no dual-functional copper-based catalytic and self-reporting particles have been reported so far. This study proposes a facile strategy to prepare high

  10. E1DS: catalytic site prediction based on 1D signatures of concurrent conservation

    OpenAIRE

    2008-01-01

    Large-scale automatic annotation of protein sequences remains challenging in postgenomics era. E1DS is designed for annotating enzyme sequences based on a repository of 1D signatures. The employed sequence signatures are derived using a novel pattern mining approach that discovers long motifs consisted of several sequential blocks (conserved segments). Each of the sequential blocks is considerably conserved among the protein members of an EC group. Moreover, a signature includes at least thre...

  11. Catalytic graphitization of polyacrylonitrile-based carbon fibers coated with Prussian blue

    Institute of Scientific and Technical Information of China (English)

    PENG Qi-ling; ZHOU Hai-hui; HUANG Zhen-hua; CHEN Jin-hua; KUANG Ya-fei

    2010-01-01

    Prussian blue(PB)was used as catalyst to improve the extent of graphitization of polyacrylonitrile(PAN)-based carbon fibers.PB was deposited on carbon fibers by anodic electrodeposition and the thickness of PB coating(PB content)was controlled by adjusting the electrodeposition time.PAN-based carbon fibers with PB coating were heat-treated and the extent of graphitization was measured by X-ray diffractometry and Raman spectroscopy.The results indicate that the extent of graphitization of PAN-based carbon fibers is enhanced in the presence of the coating.When the PB-coated carbon fibers were heat-treated at 1 900 ℃,interlayer spacing(d002)and crystallite size(Lc)reach 0.336 8 and 21.2 nm respectively.Contrarily,the values of d002 and Lc are 0.341 4 and7.4 nm respectively when the bare carbon fibers were heat-treated at 2 800℃.Compared with the bare carbon fibers,PB can make the heat treatment temperature(HTT)drop more than 500 ℃ in order to reach the same extent of graphitization.Furthermore,the research results show that PB content also has a certain influence on the extent of graphitization at the same HTT.

  12. Reduced graphene oxide wrapped Fe3O4-Co3O4 yolk-shell nanostructures for advanced catalytic oxidation based on sulfate radicals

    Science.gov (United States)

    Zhang, Lishu; Yang, Xijia; Han, Erfen; Zhao, Lijun; Lian, Jianshe

    2017-02-01

    In this work, we designed and synthesized a high performance catalyst of reduced graphene oxide (RGO) wrapped Fe3O4-Co3O4 (RGO/Fe3O4-Co3O4) yolk-shell nanostructures for advanced catalytic oxidation based on sulfate radicals. The synergistic catalytic action of the RGO/Fe3O4-Co3O4 yolk-shell nanostructures activate the peroxymonosulfate (PMS) to produce sulfate radicals (SO4rad -) for organic dyes degradation, and the Orange II can be almost completely degradated in 5 min. Meanwhile the RGO wrapping prevents the loss of cobalt in the catalytic process, and the RGO/Fe3O4-Co3O4 can be recycled after catalyzed reaction due to the presence of magnetic iron core. What's more, it can maintain almost the same high catalytic activity even after 10 cycles through repeated NaBH4 reduction treatment. Hence, RGO/Fe3O4-Co3O4 yolk-shell nanostructures possess a great opportunity to become a promising candidate for waste water treatment in industry.

  13. Synthesis, oxygenation and catalytic performance of manganese complex with p-aminomethyl benzoic acid Schiff base

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    The amino acid Schiff base complex (Sal-AMBA-Mn) was prepared with p-amino-methylbenzoic acid, salicylaldehyde N-dimethylformamide solution was investigated. The results show that lower temperature is in favor of the oxygenation, and energy,dehydroepiandrosterone acetate is effectively oxidized by molecular oxygen and the corresponding enone 7-keto-dehydroepiandrosterone acetate is obtained. The yield is 62.1% when the oxidation is carried out under the reaction conditions of 60℃C, 2 MPa of O2 pressure, C5H5N as a solvent and molar ratio of the substrate to the complex of 1:10.

  14. High Efficiency Solar-based Catalytic Structure for CO{sub 2} Reforming

    Energy Technology Data Exchange (ETDEWEB)

    Menkara, Hisham

    2013-09-30

    Throughout this project, we developed and optimized various photocatalyst structures for CO{sub 2} reforming into hydrocarbon fuels and various commodity chemical products. We also built several closed-loop and continuous fixed-bed photocatalytic reactor system prototypes for a larger-scale demonstration of CO{sub 2} reforming into hydrocarbons, mainly methane and formic acid. The results achieved have indicated that with each type of reactor and structure, high reforming yields can be obtained by refining the structural and operational conditions of the reactor, as well as by using various sacrificial agents (hole scavengers). We have also demonstrated, for the first time, that an aqueous solution containing acid whey (a common bio waste) is a highly effective hole scavenger for a solar-based photocatalytic reactor system and can help reform CO{sub 2} into several products at once. The optimization tasks performed throughout the project have resulted in efficiency increase in our conventional reactors from an initial 0.02% to about 0.25%, which is 10X higher than our original project goal. When acid whey was used as a sacrificial agent, the achieved energy efficiency for formic acid alone was ~0.4%, which is 16X that of our original project goal and higher than anything ever reported for a solar-based photocatalytic reactor. Therefore, by carefully selecting sacrificial agents, it should be possible to reach energy efficiency in the range of the photosynthetic efficiency of typical crop and biofuel plants (1-3%).

  15. Synthesis, characterization, biological and catalytic applications of transition metal complexes derived from Schiff base.

    Science.gov (United States)

    Bushra Begum, A; Rekha, N D; Vasantha Kumar, B C; Lakshmi Ranganatha, V; Khanum, Shaukath Ara

    2014-08-01

    A novel series of Cu(II), Ni(II), Zn(II), Co(II), and Cd(II) complexes have been synthesized from the Schiff base. Structural features were determined by analytical and spectral techniques like IR, (1)H NMR, UV-vis, elemental analysis, molar electric conductibility, magnetic susceptibility and thermal studies. The complexes are found to be soluble in dimethylformamide and dimethylsulfoxide. Molar conductance values in dimethylformamide indicate the non-electrolytic nature of the complexes. Binding of synthesized complexes with calf thymus DNA (CT DNA) was studied. There is significant binding of DNA in lanes 2, 3, and 5. Lanes 4 and 6 are showing more florescence when compared to the control indicating that these molecules are strongly bound to the DNA by inserting themselves between the two stacked base pairs and exhibiting their original property of fluorescence. Angiogenesis study has revealed that the compounds B-2, B-4 and B-5 have potent antitumor efficacy and activation of antiangiogenesis could be one of the possible underlying mechanisms of tumor inhibition.

  16. Synthesis, catalytic and biological activity of novel dinuclear copper complex with Schiff base

    Institute of Scientific and Technical Information of China (English)

    WEI; Danyi; LI; Ning; LU; Gui; YAO; Kemin

    2006-01-01

    A novel dinuclear copper complex with tetraglycol aldehyde-phenylalanine Schiff base has been synthesized. It was characterized and formulated as [Cu2L(NO3)]NO3 by elemental analysis,magnetic susceptibility, TG-DTA, IR, EPR and 1H NMR spectra. The obtained complex can be used as a good catalyst for the polymerization of methyl methacrylate (MMA). The optimum polymerization conditions are: MMNcatalyst = 500 (molar ratio); [catalyst] = 7.5×10-3 mol. L-1; dioxane as solvent;80℃; 6 h. Polymethyl methacrylate (PMMA) with 80% conversion, 7.2×105 viscosity-average molecular weight and 60.5% syndiotacticity was obtained. This complex has also been shown to play an important role in scavenging O-·2.

  17. Catalytic graphitization of Mo-B-doped polyacrylonitrile(PAN)-based carbon fibers

    Institute of Scientific and Technical Information of China (English)

    XU Shi-hai; ZHANG Feng-ying; LIU Shao-huan; HE Dong-mei; CAI Qing-yun

    2010-01-01

    A novel carbon fiber pretreatment was proposed.Polyacrylonitrile(PAN)-based carbon fibers were first anodized in H3PO4electrolyte to achieve an active surface,and then coated with Mo-B catalysts by immersed the carbon fibers in a uniformly dispersed Mo-B sol.The as-treated carbon fibers were then graphitized at 2 400 ℃ for 2 h.The structural changes were characterized by X-ray diffractometry(XRD),Raman spectroscopy,scanning electron microscopy(SEM)and high-resolution transmission electronic microscopy(HRTEM).The results show that much better graphitization can be achieved in the presence of Mo-B,with an interlayer spacing(d002)of 0.335 8 nm and a crystalline size(Lc)of 28 nm.

  18. Catalytic Properties of ZSM-5 based Cu-Zn Catalysts Applies to Ethanol Synthesis from Syngas

    Directory of Open Access Journals (Sweden)

    Xu He-Shuang

    2016-01-01

    Full Text Available Cu-Zn catalysts based on ZSM-5 were prepared with impregnation method. Their catalatic behaviors for the synthesis of ethanol from syngas were investigated in a fixed bed. XRD and H2-TPR were adopted to characterize the structure and of the catalysts. In the synthesis procession, such factors as ZSM-5 with varied n(Si/n(Al ratio, reaction temperature and space velocity were inspected carefully. The results showed that: changing the ratio of silica to alumina in the carrier zeolite has a great influence on the conversion of CO.with a n(Si/n(Al ratio of 80, the conversion rate of CO peaked at 25% and the selectivity to ethanol reached 22%. Optimal space velocity for Cu-Zn catalysts was 8400·mL−1·h−1·g−1.

  19. Enhanced wet hydrogen peroxide catalytic oxidation performances based on CuS nanocrystals/reduced graphene oxide composites

    Science.gov (United States)

    Qian, Jing; Wang, Kun; Guan, Qingmeng; Li, Henan; Xu, Hui; Liu, Qian; Liu, Wei; Qiu, Baijing

    2014-01-01

    CuS nanocrystals/reduced graphene oxide (CuS NCs/rGO) composites were prepared by a facile one-pot solvothermal reaction. In this solvothermal system, thioacetamide was found to perform the dual roles of sulphide source and reducing agent, resulting in the formation of CuS NCs and simultaneous reduction of graphene oxide (GO) sheets to rGO sheets. In addition, CuS NCs/rGO composites were further used as heterogeneous catalysts in the wet hydrogen peroxide catalytic oxidation process, with methylene blue as a model organic dye. The introduction of rGO to CuS NCs could effectively enhance the catalytic activity of CuS NCs, and the resultant CuS NCs/rGO composites with a starting GO amount of 5 wt% showed the highest catalytic activity. Furthermore, the CuS NCs/rGO composites showed high catalytic activity over a broad pH operation range from 3.0 to 11.0 under ambient conditions, and still retained 90% of the original catalytic activity after reuse in five cycles.

  20. 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.

  1. Environmental Technology Verification: Test Report of Mobile Source Selective Catalytic Reduction--Nett Technologies, Inc., BlueMAX 100 version A urea-based selective catalytic reduction technology

    Science.gov (United States)

    Nett Technologies’ BlueMAX 100 version A Urea-Based SCR System utilizes a zeolite catalyst coating on a cordierite honeycomb substrate for heavy-duty diesel nonroad engines for use with commercial ultra-low–sulfur diesel fuel. This environmental technology verification (ETV) repo...

  2. Model-based Derivation of the Safety Operating Limits of a Semi-batch Reactor for the Catalytic Acetoacetylation of Pyrrole Using a Generalized Sensitivity Criterion

    OpenAIRE

    Maria, G; A Dan; Stefan, D.-N.

    2010-01-01

    The safe operation of a semi-batch catalytic reactor remains a sensitive issue when highly exothermic side reactions may occur, and various elements such as controllability, stability, safety, and economic aspects have to be considered in the process development. Nominal operating conditions are set to avoid excessive thermal sensitivity to variations in the process parameters. Several shortcuts or model-based methods are used to estimate the safety limits and runaway boundaries for the op...

  3. Effect of preparation methods of aluminum emulsions on catalytic performance of copper-based catalysts for methanol synthesis from syngas

    Institute of Scientific and Technical Information of China (English)

    Lili Wang; Wen Ding; Yingwei Liu; Weiping Fang; Yiquan Yang

    2010-01-01

    Various Cu/ZnO/Al2O3 catalysts have been synthesized by different aluminum emulsions as aluminum sources and their performances for methanol synthesis from syngas have been investigated.The influences of preparation methods of aluminum emulsions on physicochemical and catalytic properties of catalysts were studied by XRD,SEM,XPS,N2 adsorption-desorption techniques and methanol synthesis from syngas.The preparation methods of aluminum emulsions were found to influence the catalytic activity,CuO crystallite size,surface area and Cu0 surface area and reduction process.The results show that the catalyst CN using the aluminum source prepared by addition the ammonia into the aluminum nitrate (NP) exhibited the best catalytic performance for methanol synthesis from syngas.

  4. Carbon-based catalysts:Opening new scenario to develop next-generation nano-engineered catalytic materials

    Institute of Scientific and Technical Information of China (English)

    Claudio Ampelli; Siglinda Perathoner; Gabriele Centi

    2014-01-01

    This essay analyses some of the recent development in nanocarbons (carbon materials having a defined and controlled nano-scale dimension and functional properties which strongly depend on their nano-scale features and architecture), with reference to their use as advanced catalytic materials. It is remarked how their features open new possibilities for catalysis and that they represent a new class of catalytic materials. Although carbon is used from long time in catalysis as support and electrocatalytic applications, nanocarbons offer unconventional ways for their utilization and to address some of the new challenges deriving from moving to a more sustainable future. This essay comments how nanocarbons are a key element to develop next-generation catalytic materials, but remarking that this goal requires overcoming some of the actual limits in current research. Some aspects are discussed to give a glimpse on new directions and needs for R&D to progress in this direction.

  5. The effect of copper valence on catalytic combustion of styrene over the copper based catalysts in the absence and presence of water vapor☆

    Institute of Scientific and Technical Information of China (English)

    Hongyan Pan; Zhiyan He; Qian Lin; Fei Liu; Zhong Li

    2016-01-01

    Catalysts CuOx/γ-Al2O3-IH and CuOx/γ-Al2O3-IM were prepared, characterized, and tested for styrene combustion in the absence and presence of water vapor. The effect of copper valence of the catalysts on the catalytic activity for styrene combustion was discussed using the theory of hard soft acids and bases (HSAB). The results showed that the existence of water vapor in feed stream inhibited the catalytic activity for styrene combustion due to the competition adsorption of water molecule. HSAB theory confirmed that the local soft acidity of the catalyst CuOx/γ-Al2O3-IH was much stronger than that of the catalyst CuOx/γ-Al2O3-IM because of the higher content of soft acid Cu+on its surface, which increased the adsorption ability toward soft base of styrene and reduced the adsorption toward hard base of water vapor, and thus increased the catalytic activity for styrene combustion and weakened the negative influence of water vapor.

  6. Promotional Effect of Ce on Iron-Based Catalysts for Selective Catalytic Reduction of NO with NH3

    OpenAIRE

    Xiaobo Wang; Lei Zhang; Shiguo Wu; Weixin Zou; Shuohan Yu; Ye Shao; Lin Dong

    2016-01-01

    A series of Fe–Ce–Ti catalysts were prepared via co-precipitation method to investigate the effect of doping Ce into Fe–Ti catalysts for selective catalytic reduction of NO with NH3. The NO conversion over Fe–Ce–Ti catalysts was considerably improved after Ce doping compared to that of Fe–Ti catalysts. The Fe(0.2)–Ce(0.4)–Ti catalysts exhibited superior catalytic activity to that of Fe(0.2)–Ti catalysts. The obtained catalysts were characterized by N2 adsorption (BET), X-ray diffraction (XRD)...

  7. General base catalysis in the urate oxidase reaction: evidence for a novel Thr-Lys catalytic diad.

    Science.gov (United States)

    Imhoff, Rebecca D; Power, Nicholas P; Borrok, M Jack; Tipton, Peter A

    2003-04-15

    Urate oxidase catalyzes the oxidation of urate without the involvement of any cofactors. The gene encoding urate oxidase from Bacillus subtilis has been cloned and expressed, and the enzyme was purified and characterized. Formation of the urate dianion is believed to be a key step in the oxidative reaction. Rapid-mixing chemical quench studies provide evidence that the dianion is indeed an intermediate; at 15 degrees C the dianion forms within the mixing time of the rapid-quench instrument, and it disappears with a rate constant of 8 s(-)(1). Steady-state kinetic studies indicate that an ionizable group on the enzyme with a pK of 6.4 must be unprotonated for catalysis, and it is presumed that the role of this group is to abstract a proton from the substrate. Surprisingly, examination of the active site provided by the previously reported crystal structure does not reveal any obvious candidates to act as the general base. However, Thr 69 is hydrogen-bonded to the ligand at the active site, and Lys 9, which does not contact the ligand, is hydrogen-bonded to Thr 69. The T69A mutant enzyme has a V(max) that is 3% of wild type, and the K9M mutant enzyme has a V(max) that is 0.4% of wild type. The ionization at pH 6.4 that is observed with wild-type enzyme is absent in both of these mutants. It is proposed that these residues form a catalytic diad in which K9 deprotonates T69 to allow it to abstract the proton from the N9 position of the substrate to generate the dianion.

  8. DRIFT study of manganese/ titania-based catalysts for low-temperature selective catalytic reduction of NO with NH3.

    Science.gov (United States)

    Wu, Zhongbiao; Jiang, Boqiong; Liu, Yue; Wang, Haiqiang; Jin, Ruiben

    2007-08-15

    Manganese oxides and iron-manganese oxides supported on TiO2 were prepared by the sol-gel method and used for low-temperature selective catalytic reduction (SCR) of NO with NH3. Base on the previous study, Mn(0.4)/ TiO2 and Fe(0.1)-Mn(0.4)/TiO2 were then selected to carry out the in situ diffuse reflectance infrared transform spectroscopy (DRIFT) investigation for revealing the reaction mechanism. The DRIFT spectroscopy for the adsorption of NH3 indicated the presence of coordinated NH3 and NH4+ on both of the two catalysts. When NO was introduced, the coordinated NH3 on the catalyst surface was consumed rapidly, indicating these species could react with NO effectively. When NH3 was introduced into the sample preadsorbed with NO + O2, SCR reaction would not proceed on Mn(0.4)/TiO2. However, for Fe(0.1)-Mn(0.4)/ TiO2 the bands due to coordinated NH3 on Fe2O3 were formed. Simultaneously, the bidentate nitrates were transformed to monodentate nitrates and NH4+ was detected. And NO2 from the oxidation of NO on catalyst could react with NH4+ leading to the reduction of NO. Therefore, it was suggested that the SCR reaction on Fe(0.1)-Mn(0.4)/TiO2 could also take place in a different way from the reactions on Mn(0.4)/TiO2 proposed by other researchers. Furthermore, the SCR reaction steps for these two kinds of catalysts were proposed.

  9. Synergic catalytic effect of Ti hydride and Nb nanoparticles for improving hydrogenation and dehydrogenation kinetics of Mg-based nanocomposite

    Directory of Open Access Journals (Sweden)

    Xiujuan Ma

    2017-02-01

    Full Text Available The Mg-9.3 wt% (TiH1.971-TiH−0.7 wt% Nb nanocomposite has been synthesized by hydrogen plasma-metal reaction (HPMR approach to enhance the hydrogen sorption kinetics of Mg at moderate temperatures by providing nanosizing effect of increasing H “diffusion channels” and adding transition metallic catalysts. The Mg nanoparticles (NPs were in hexagonal shape range from 50 to 350 nm and the average size of the NPs was 177 nm. The small spherical TiH1.971, TiH and Nb NPs of about 25 nm uniformly decorated on the surface of the big Mg NPs. The Mg-TiH1.971-TiH-Nb nanocomposite could quickly absorb 5.6 wt% H2 within 5 min at 573 K and 4.5 wt% H2 within 5 min at 523 K, whereas the pure Mg prepared by HPMR could only absorb 4 and 1.5 wt% H2 at the same temperatures. TiH1.971, TiH and Nb NPs transformed into TiH2 and NbH during hydrogenation and recovered after dehydrogenation process. The apparent activation energies of the nanocomposite for hydrogenation and dehydrogenation were 45.0 and 50.7 kJ mol−1, which are much smaller than those of pure Mg NPs, 123.8 and 127.7 kJ mol−1. The improved sorption kinetics of the Mg-based nanocomposite at moderate temperatures and the small activation energy can be interpreted by the nanostructure of Mg and the synergic catalytic effects of Ti hydrides and Nb NPs.

  10. Low-temperature growth of nitrogen-doped carbon nanofibers by acetonitrile catalytic CVD using Ni-based catalysts

    Directory of Open Access Journals (Sweden)

    Tomohiro Iwasaki

    2016-06-01

    Full Text Available Abstract To synthesize nitrogen-doped carbon nanofibers (N-CNFs at high growth rates and low temperatures less than 673 K, nickel species (metallic nickel and nickel oxide supported on alumina particles were used as the catalysts for an acetonitrile catalytic chemical vapor deposition (CVD process. The nickel:alumina mass ratio in the catalysts was fixed at 0.05:1. The catalyst precursors were prepared from various nickel salts (nitrate, chloride, sulfate, acetate, and lactate and then calcined at 1073 K for 1 h in oxidative (air, reductive (hydrogen-containing argon, or inert (pure argon atmospheres to activate the nickel-based catalysts. The effects of precursors and calcination atmosphere on the catalyst activity at low temperatures were studied. We found that the catalysts derived from nickel nitrate had relatively small crystallite sizes of nickel species and provided N-CNFs at high growth rates of 57 ± 4 g-CNF/g-Ni/h at 673 K in the CVD process using 10 vol% hydrogen-containing argon as the carrier gas of acetonitrile vapor, which were approximately 4 times larger than that of a conventional CVD process. The obtained results reveal that nitrate ions in the catalyst precursor and hydrogen in the carrier gas can contribute effectively to the activation of catalysts in low-temperature CVD. The fiber diameter and nitrogen content of N-CNFs synthesized at high growth rates were several tens of nanometers and 3.5 ± 0.3 at.%, respectively. Our catalysts and CVD process may lead to cost reductions in the production of N-CNFs.

  11. Low-temperature growth of nitrogen-doped carbon nanofibers by acetonitrile catalytic CVD using Ni-based catalysts

    Science.gov (United States)

    Iwasaki, Tomohiro; Makino, Yuri; Fukukawa, Makoto; Nakamura, Hideya; Watano, Satoru

    2016-11-01

    To synthesize nitrogen-doped carbon nanofibers (N-CNFs) at high growth rates and low temperatures less than 673 K, nickel species (metallic nickel and nickel oxide) supported on alumina particles were used as the catalysts for an acetonitrile catalytic chemical vapor deposition (CVD) process. The nickel:alumina mass ratio in the catalysts was fixed at 0.05:1. The catalyst precursors were prepared from various nickel salts (nitrate, chloride, sulfate, acetate, and lactate) and then calcined at 1073 K for 1 h in oxidative (air), reductive (hydrogen-containing argon), or inert (pure argon) atmospheres to activate the nickel-based catalysts. The effects of precursors and calcination atmosphere on the catalyst activity at low temperatures were studied. We found that the catalysts derived from nickel nitrate had relatively small crystallite sizes of nickel species and provided N-CNFs at high growth rates of 57 ± 4 g-CNF/g-Ni/h at 673 K in the CVD process using 10 vol% hydrogen-containing argon as the carrier gas of acetonitrile vapor, which were approximately 4 times larger than that of a conventional CVD process. The obtained results reveal that nitrate ions in the catalyst precursor and hydrogen in the carrier gas can contribute effectively to the activation of catalysts in low-temperature CVD. The fiber diameter and nitrogen content of N-CNFs synthesized at high growth rates were several tens of nanometers and 3.5 ± 0.3 at.%, respectively. Our catalysts and CVD process may lead to cost reductions in the production of N-CNFs.

  12. Synthesis, characterizations and catalytic studies of a new two-dimensional metal−organic framework based on Co–carboxylate secondary building units

    Energy Technology Data Exchange (ETDEWEB)

    Bagherzadeh, Mojtaba, E-mail: bagherzadeh@sharif.edu [Department of Chemistry, Sharif University of Technology, PO Box 11155-3516, Tehran (Iran, Islamic Republic of); Ashouri, Fatemeh [Department of Chemistry, Sharif University of Technology, PO Box 11155-3516, Tehran (Iran, Islamic Republic of); Đaković, Marijana [Department of Chemistry, Faculty of Science, University of Zagreb, Zagreb (Croatia)

    2015-03-15

    A metal–organic framework [Co{sub 3}(BDC){sub 3}(DMF){sub 2}(H{sub 2}O){sub 2}] was synthesized and structurally characterized. X-ray single crystal analysis revealed that the framework contains a 2D polymeric chain through coordination of 1,4-benzenedicarboxylic acid linker ligand to cobalt centers. The polymer crystallize in monoclinic P2{sub 1}/n space group with a=13.989(3) Å, b=9.6728(17) Å, c=16.707(3) Å, and Z=2. The polymer features a framework based on the perfect octahedral Co–O6 secondary building units. The catalytic activities of [Co{sub 3}(BDC){sub 3}(DMF){sub 2}(H{sub 2}O){sub 2}]{sub n} for olefins oxidation was conducted. The heterogeneous catalyst could be facilely separated from the reaction mixture, and reused three times without significant degradation in catalytic activity. Furthermore, no contribution from homogeneous catalysis of active species leaching into reaction solution was detected. - Graphical abstract: A metal–organic framework of [Co{sub 3}(BDC){sub 3}(DMF){sub 2}(H{sub 2}O){sub 2}] was synthesized by hydrothermal method. This 2D-periodic framework is constructed from the infinite Co–O–C secondary building units and crystallizes in the monoclinic P2{sub 1}/n space group based on Co(II)–carboxylate units. The catalytic oxidation of various olefins was effectively carried out with [Co{sub 3}(BDC){sub 3}(DMF){sub 2}(H{sub 2}O){sub 2}]{sub n} catalyst by TBHP as oxidant. - Highlights: • A metal–organic framework of [Co{sub 3}(BDC){sub 3}(DMF){sub 2}(H{sub 2}O){sub 2}] is prepared by hydrothermal method. • The [Co{sub 3}(BDC){sub 3}(DMF){sub 2}(H{sub 2}O){sub 2}]{sub n} is constructed from Co–carboxylate secondary building units. • This coordination polymer displayed high catalytic activity for olefin oxidation reactions. • The catalytic reaction is heterogeneous and catalyst can be simply separated. • The heterogeneous catalyst can be reused several times without significant loss of catalytic activity.

  13. Synthesis, spectroscopic characterization and catalytic oxidation properties of ONO/ONS donor Schiff base ruthenium(III) complexes containing PPh3/AsPh3

    Indian Academy of Sciences (India)

    Priyarega; M Muthu Tamizh; R Karvembu; R Prabhakaran; K Natarajan

    2011-05-01

    Six different ruthenium(III) complexes of Schiff bases derived from 2-hydroxy-1-naphthaldehyde and -aminophenol/-aminothiophenol have been synthesized. The compounds with the general formula [RuX(EPh3)2(L)] (X = Cl or Br; E = P or As; L = bifunctional tridentate ONO/ONS donor Schiff base ligand) were characterized by infrared, electronic, electron paramagnetic resonance spectroscopy and elemental analyses. Spectroscopic investigation reveals coordination of Schiff base ligand through ONO/ONS donor atoms and octahedral geometry around ruthenium metal. Redox property of complexes has been examined by using cyclic voltammetry. The catalytic oxidation property of ruthenium(III) complexes were also investigated.

  14. Effects of sol-gel method and lanthanum addition on catalytic performances of nickel-based catalysts for methane reforming with carbon dioxide

    Institute of Scientific and Technical Information of China (English)

    LI Xiancai; HU Quanhong; YANG Yifeng; CHEN Juanrong; LAI Zhihua

    2008-01-01

    The nickel-based catalysts were prepared by the sol-gel method and used for the CH4 reforming with CO2. The effects of the sol-gel method on the specific surface area, catalytic activity, desorption, and reduction performances of catalysts were investigated with BET, TPR, and TPD. Compared with the catalyst prepared by the impregnation method, the results indicated that the catalysts prepared by the sol-gel method had larger specific surface area, showing higher catalytic activities and exhibiting perfect desorption and reduction per-formances. In addition, the modification effects of adding La were studied, and it was found that the 0.75NLBT catalyst constituted of 5wt.%Ni-0.75wt.%La was optimal.

  15. The effect of preparation factors on the structural and catalytic properties of mesoporous nanocrystalline iron-based catalysts for high temperature water gas shift reaction

    Energy Technology Data Exchange (ETDEWEB)

    Meshkani, Fereshteh; Rezaei, Mehran [University of Kashan, Kashan (Iran, Islamic Republic of)

    2015-07-15

    A systematic study was done on the effect of preparation factors on the structural and catalytic properties of mesoporous nanocrystalline iron-based catalysts in high temperature water gas shift reaction. The catalysts were prepared by coprecipitation method, and the effect of the main preparation factors (pH, refluxing temperature, refluxing time, concentration of the precursors solution) was studied. The catalysts were characterized by powder X-ray diffraction (XRD), N{sub 2} adsorption (BET), Temperature programmed reduction (TPR), transmission and scanning electron microscopies (TEM, SEM) techniques. The results revealed that the preparation factors affected the textural and catalytic properties of the Fe-Cr-Cu catalyst. The results showed that the prepared catalyst with the highest activity showed higher specific surface area compared to commercial catalyst and consequently exhibited higher activity in high temperature water gas shift reaction. The TEM analysis showed a nanostructure for this sample with crystallite size less than 20 nm.

  16. Local Environment and Nature of Cu Active Sites in Zeolite-Based Catalysts for the Selective Catalytic Reduction of NOx

    NARCIS (Netherlands)

    Deka, U.; Lezcano-Gonzalez, I.; Weckhuysen, B.M.; Beale, A.M.

    2013-01-01

    Cu-exchanged zeolites have demonstrated widespread use as catalyst materials in the abatement of NOx, especially from mobile sources. Recent studies focusing on Cu-exchanged zeolites with the CHA structure have demonstrated them to be excellent catalysts in the ammonia-assisted selective catalytic r

  17. Histidine-40 of ribonuclease T1 acts as base catalyst when the true catalytic base, glutamic acid-58, is replaced by alanine.

    Science.gov (United States)

    Steyaert, J; Hallenga, K; Wyns, L; Stanssens, P

    1990-09-25

    Mechanisms for the ribonuclease T1 (RNase T1; EC 3.1.27.3) catalyzed transesterification reaction generally include the proposal that Glu58 and His92 provide general base and general acid assistance, respectively [Heinemann, U., & Saenger, W. (1982) Nature (London) 299, 27-31]. This view was recently challenged by the observation that mutants substituted at position 58 retain high residual activity; a revised mechanism was proposed in which His40, and not Glu58, is engaged in catalysis as general base [Nishikawa, S., Morioka, H., Kim, H., Fuchimura, K., Tanaka, T., Uesugi, S., Hakoshima, T., Tomita, K., Ohtsuka, E., & Ikehara, M. (1987) Biochemistry 26, 8620-8624]. To clarify the functional roles of His40, Glu58, and His92, we analyzed the consequences of several amino acid substitutions (His40Ala, His40Lys, His40Asp, Glu58Ala, Glu58Gln, and His92Gln) on the kinetics of GpC transesterification. The dominant effect of all mutations is on Kcat, implicating His40, Glu58, and His92 in catalysis rather than in substrate binding. Plots of log (Kcat/Km) vs pH for wild-type, His40Lys, and Glu58Ala RNase T1, together with the NMR-determined pKa values of the histidines of these enzymes, strongly support the view that Glu58-His92 acts as the base-acid couple. The curves also show that His40 is required in its protonated form for optimal activity of wild-type enzyme. We propose that the charged His40 participates in electrostatic stabilization of the transition state; the magnitude of the catalytic defect (a factor of 2000) from the His40 to Ala replacement suggests that electrostatic catalysis contributes considerably to the overall rate acceleration. For Glu58Ala RNase T1, the pH dependence of the catalytic parameters suggests an altered mechanism in which His40 and His92 act as base and acid catalyst, respectively. The ability of His40 to adopt the function of general base must account for the significant activity remaining in Glu58-mutated enzymes.

  18. 希夫碱类金属配合物催化剂催化氧化烯烃研究进展%Progress in research of Schiff base metal complexes catalytic using for olefins catalytic oxidation

    Institute of Scientific and Technical Information of China (English)

    冯辉霞; 李汉峰; 王利杰

    2011-01-01

    The structure of metal complexes characteristic of Schiff base was analyzed and catalytic oxidation olefins was studied on current situation systematically.And it expressed the classification application of Schiff base which used in type of homogeneous catalysis oxidization and metal complexes of solid catalyst.By analyzing the defects of small molecules metal complexes catalysis-oxidization olefins,the conclusion indicated that the heterogeneous load type of metal complexes of Schiff base in category catalyst is the main development direction in present.%分析了希夫碱金属配合物的结构特点及其催化氧化烯烃的研究现状,阐述了用于均相催化氧化的希夫碱、固载型希夫碱金属配合物催化剂的分类及其在氧化烯烃领域的应用研究.通过分析希夫碱类小分子金属配合物催化氧化烯烃的缺陷,得出非均相的负载型希夫碱类金属配合物催化剂是目前主要发展方向的结论.

  19. β-Amino acid catalyzed asymmetric Michael additions: design of organocatalysts with catalytic acid/base dyad inspired by serine proteases.

    Science.gov (United States)

    Yang, Hui; Wong, Ming Wah

    2011-09-16

    A new type of chiral β-amino acid catalyst has been computationally designed, mimicking the enzyme catalysis of serine proteases. Our catalyst approach is based on the bioinspired catalytic acid/base dyad, namely, a carboxyl and imidazole pair. DFT calculations predict that this designed organocatalyst catalyzes Michael additions of aldehydes to nitroalkenes with excellent enantioselectivities and remarkably high anti diastereoselectivities. The unusual stacked geometry of the enamine intermediate, hydrogen bonding network, and the adoption of an exo transition state are the keys to understand the stereoselectivity.

  20. Preparation of acid-base bifunctional mesoporous KIT-6 (KIT: Korea Advanced Institute of Science and Technology) and its catalytic performance in Knoevenagel reaction

    Energy Technology Data Exchange (ETDEWEB)

    Xu, Ling [College of Chemistry and Chemical Engineering, Inner Mongolia University for Nationalities, Tongliao 028000 (China); Wang, Chunhua [Key Laboratory of Surface and Interface Chemistry of Jilin Province, College of Chemistry, Jilin University, Changchun 130023 (China); Guan, Jingqi, E-mail: guanjq@jlu.edu.cn [Key Laboratory of Surface and Interface Chemistry of Jilin Province, College of Chemistry, Jilin University, Changchun 130023 (China)

    2014-05-01

    Acid-base bifunctional mesoporous catalysts Al-KIT-6-NH{sub 2} containing different aluminum content have been synthesized through post synthetic grafting method. The materials were characterized by X-ray diffraction (XRD), scanning electron micrographs (SEM), transmission electron micrographs (TEM), Fourier-transform infrared spectroscopy (FTIR), IR spectra of pyridine adsorption, NH{sub 3}-TPD and TG analysis. The characterization results indicated that the pore structure of KIT-6 was well kept after the addition of aluminum and grafting of aminopropyl groups. The acid amount of Al-KIT-6 increased with enhancing aluminum content. Catalytic results showed that weak acid and weak base favor the Knoevenagel reaction, while catalysts with strong acid and weak base exhibited worse catalytic behavior. - Graphical abstract: The postulated steps of mechanism for the acid-base catalyzed process are as follows: (1) the aldehyde gets activated by the surface acidic sites which allow the amine undergoes nucleophilic to attack the carbonyl carbon of benzaldehyde. (2) Water is released in the formation of imine intermediate. (3) The ethyl cyanoacetate reacts with the intermediate. (4) The benzylidene ethyl cyanoacetate is formed and the amine is regenerated. - Highlights: • KIT-6 and Al-KIT-6-NH{sub 2} with different Si/Al ratios has been successfully prepared. • 79.4% Yield was obtained over 46-Al-KIT-6-NH{sub 2} within 20 min in Knoevenagel reaction. • Low Al-content Al-KIT-6-NH{sub 2} shows better catalytic stability than high Al-content catalysts. • There is acid-base synergistic effect in Knoevenagel reaction.

  1. 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.

  2. Promotional Effect of Ce on Iron-Based Catalysts for Selective Catalytic Reduction of NO with NH3

    Directory of Open Access Journals (Sweden)

    Xiaobo Wang

    2016-07-01

    Full Text Available A series of Fe–Ce–Ti catalysts were prepared via co-precipitation method to investigate the effect of doping Ce into Fe–Ti catalysts for selective catalytic reduction of NO with NH3. The NO conversion over Fe–Ce–Ti catalysts was considerably improved after Ce doping compared to that of Fe–Ti catalysts. The Fe(0.2–Ce(0.4–Ti catalysts exhibited superior catalytic activity to that of Fe(0.2–Ti catalysts. The obtained catalysts were characterized by N2 adsorption (BET, X-ray diffraction (XRD, temperature programmed reduction (H2-TPR, temperature programmed desorption (NH3-TPD, Fourier transform infrared (FT-IR spectrophotometry, thermogravimetric analysis (TGA, and X-ray photoelectron spectroscopy (XPS. The data showed that the introduction of Ce results in higher surface area and better dispersion of active components on the catalyst surface and enhances the amount of surface acid sites. The interactions between Fe and Ce species were found to improve the redox ability of the catalyst, which promotes catalytic performance at low temperature. The XPS results revealed that Fe3+/Fe2+ and Ce4+/Ce3+ coexisted on the catalyst surface and that Ti was in 4+ oxidation state on catalyst surface. Ce doping increased the atomic ratio of Fe/Ti and Ce/Ti and enhanced the surface adsorbed oxygen species. In addition, Fe(0.2–Ce(0.4–Ti catalyst also showed better tolerance to H2O and SO2 and up to 92% NO conversion at 270 °C with 200 ppm SO2 added over 25 h, which suggests that it is a promising industrial catalyst for mid-low temperature NH3–selective catalytic reduction (SCR reaction.

  3. Mononuclear Nickel(II Complexes with Schiff Base Ligands: Synthesis, Characterization, and Catalytic Activity in Norbornene Polymerization

    Directory of Open Access Journals (Sweden)

    Yi-Mei Xu

    2017-03-01

    Full Text Available The nickel(II catalyst has manifested higher catalytic activity compared to that of other late transition metal catalysts for norbornene polymerization. Therefore, several structurally similar trans-nickel(II compounds of N,O-chelate bidentate ligands were synthesized and characterized. Both the electronic effect and the steric hindrance influence polymerization. The molecular structures of 2, 4 and 5 were further confirmed by single-crystal X-ray diffraction.

  4. Binary and Ternary Catalytic Systems for Olefin Metathesis Based on MoCl5/SiO2

    Science.gov (United States)

    Bykov, Victor I.; Belyaev, Boris A.; Butenko, Tamara A.; Finkelshtein, Eugene Sh.

    Kinetics of α-olefin metathesis in the presence of binary (MoCl5/ SiO2-Me4Sn) and ternary catalytic systems (MoCl5/SiO2-Me4Sn-ECl4, E = Si or Ge) was studied. Specifically, kinetics and reactivity of 1-decene, 1-octene, and 1-hexene in the metathesis reaction at 27°C and 50°C in the presence of MoCl5/ SiO2-SnMe4 were examined and evaluated in detail. It was shown that experimental data comply well with the simple kinetic equation for the rate of formation of symmetrical olefins with allowance for the reverse reaction and catalyst deactivation: r = left( {k_1 \\cdot c_α - k_{ - 1} \\cdot c_s } right) \\cdot e^{ - k_d \\cdot tilde n_{tot} } . The coefficients for this equation were determined, and it was shown that these α-olefins had practically the same reactivity. It was found that reactivation in the course of metathesis took place due to the addition of a third component (silicon tetrachloride or germanium tetrachloride in combination with tetramethyltin) to a partially deactivated catalyst. The number of active centers was determined (5-6% of the amount of Mo) and the mechanisms of formation, deactivation, and reactivation were proposed for the binary and ternary catalytic systems. The role of individual components of the catalytic systems was revealed.

  5. Catalytic and peroxidase-like activity of carbon based-AuPd bimetallic nanocomposite produced using carbon dots as the reductant

    Energy Technology Data Exchange (ETDEWEB)

    Yang, Liuqing [Key Laboratory of Chemical Biology & Traditional Chinese Medicine Research (Ministry of Education, China), College of Chemistry and Chemical Engineering, Hunan Normal University, Changsha 410081 (China); Liu, Xiaoying [College of Science, Science and Technological Innovation Platform, Hunan Agricultural University, Hunan, Changsha 410128 (China); Lu, Qiujun; Huang, Na [Key Laboratory of Chemical Biology & Traditional Chinese Medicine Research (Ministry of Education, China), College of Chemistry and Chemical Engineering, Hunan Normal University, Changsha 410081 (China); Liu, Meiling, E-mail: liumeilingww@126.com [Key Laboratory of Chemical Biology & Traditional Chinese Medicine Research (Ministry of Education, China), College of Chemistry and Chemical Engineering, Hunan Normal University, Changsha 410081 (China); Zhang, Youyu; Yao, Shouzhuo [Key Laboratory of Chemical Biology & Traditional Chinese Medicine Research (Ministry of Education, China), College of Chemistry and Chemical Engineering, Hunan Normal University, Changsha 410081 (China)

    2016-08-03

    In this report, carbon-based AuPd bimetallic nanocomposite (AuPd/C NC) was synthesized using carbon dots (C-dots) as the reducing agent and stabilizer by a simple green sequential reduction strategy, without adding other agents. The as synthesized AuPd/C NC showed good catalytic activity and peroxidase-like property. The structure and morphology of these nanoparticles were clearly characterized by UV–Vis spectroscopy, X-ray photoelectron spectroscopy (XPS) and transmission electron microscopy (TEM). The AuPd/C NC catalyst exhibits noticeably higher catalytic activity than Pd and Au nanoparticles in catalysis reduction of 4-nitrophenol (4-NP). Moreover, based on the high peroxidase-like property of AuPd/C NC, a new colorimetric detection method for hydrogen peroxide (H{sub 2}O{sub 2}) has been designed using 3,3′,5,5′-tetramethyl-benzidine (TMB) as the substrate, which provides a simple and sensitive means to detect H{sub 2}O{sub 2} in wide linear range of 5 μM–500 μM and 500 μM–4 mM with low detection limit of 1.6 μM (S/N = 3). Therefore, the facile synthesis strategy for bimetallic nanoparticles by the mild reductant of carbon dot will provide some new thoughts for preparing of carbon-based metal nanomaterials and expand their application in catalysis and analytical chemistry areas. - Highlights: • Carbon-based AuPd bimetallic nanocomposite was synthesized using carbon dots. • The green sequential reduction strategy synthesis method is simple, green, convenient and effective. • The as synthesized AuPd/C NC showed good catalytic activity and peroxidase-like activity. • The AuPd/C NC exhibits noticeably higher catalytic activity in reduction of 4-nitrophenol. • A new colorimetric detection method for hydrogen peroxide based on AuPd/C NC was proposed.

  6. Construction of new biopolymer (chitosan)-based pincer-type Pd(II) complex and its catalytic application in Suzuki cross coupling reactions

    Science.gov (United States)

    Baran, Talat; Menteş, Ayfer

    2017-04-01

    In this paper we described the fabrication, characterization and application of a new biopolymer (chitosan)-based pincer-type Pd(II) catalyst in Suzuki cross coupling reactions using a non-toxic, cheap, eco-friendly and practical method. The catalytic activity tests showed remarkable product yields as well as TON (19800) and TOF (330000) values with a small catalyst loading. In addition, the catalyst indicated good recyclability in the Suzuki C-C reaction. This biopolymer supported catalyst can be used with various catalyst systems due to its unique properties, such as being inert, green in nature, low cost and chemically durable.

  7. Highly sensitive fluorescent probe for clenbuterol hydrochloride detection based on its catalytic oxidation of eosine Y by NaIO4.

    Science.gov (United States)

    Liu, Jiaming; Liu, Zhen-bo; Huang, Qitong; Lin, Chang-Qing; Lin, Xiaofeng

    2014-09-01

    A highly sensitive fluorescent probe for clenbuterol hydrochloride (CLB) detection has been first designed based on its catalytic effect on NaIO4 oxidating eosine Y (R). And this environment-friendly, simple, rapid, selective and sensitive fluorescent probe has been utilized to detect CLB in the practical samples with the results consisting with those obtained by GC/MS. The structures of R and CLB were characterized by infrared spectra. The mechanism of the proposed assay for the detection of CLB was also discussed.

  8. Theoretical studies on the interaction between the nitrile-based inhibitors and the catalytic triad of Cathepsin K.

    Science.gov (United States)

    Pitchumani Violet Mary, C; Shankar, R; Vijayakumar, S

    2017-02-20

    Computational studies on the interaction of novel inhibitor compounds with the Cathepsin K protease have been performed to study the inhibition properties of the inhibitor compounds. The quantum chemical calculations have been performed to analyze the molecular geometries, structural stability, reactivity, nature of interaction, and the charge transfer properties using B3LYP level of theory by implementing 6-311g(d,p) basis set. The calculated C-S and N-H…N bond lengths of the inhibitor-triad complexes are found to agree well with the previous literature results. The chemical reactivity of the inhibitors and catalytic triad are analyzed through frontier molecular orbital analysis and found that the inhibitors are subjected to nucleophilic attack by the catalytic triad. The nature of inhibition of the inhibitor compounds is examined using the quantum theory of Atoms in Molecules analysis and found to be partially covalent. The NBO stabilization energy for the Cys - inhibitor are found to be most stable than the other interactions. The molecular dynamic simulations were performed to study the influence of dynamic of the active site on the QM results. The many body decomposition interaction energy calculated for the final results of MD simulation reveals that the dynamic of the active site induces significant changes in the interaction energy and occupancy of H-bonds plays a major role in the stabilizing the active site inhibitor interactions. The present study reveals that the inhibitor compounds can inhibit the proteolytic activity of the proteases on binding with the catalytic active site.

  9. [Experimental studies on low-temperature selective catalytic reduction of NO on magnetic iron-based catalysts].

    Science.gov (United States)

    Yao, Gui-huan; Zhang, Qi; Qin, Ye; Wang, Fang; Lu, Fang; Gui, Ke-ting

    2009-10-15

    Low-temperature selective catalytic reduction (SCR) of NO is a new technique needing urgent development in flue gas cleaning. Elementary studies were done about selective catalytic reduction of NO from flue gas on magnetic iron oxides with ammonia at low and medium temperatures in a fluidized bed, such as Fe3O4 and gamma-Fe2O3. Magnetic field effects for NO removal on gamma-Fe2O3 were also researched with low assisted magnetic fileds. X-ray diffraction spectroscopy was used to identify and characterize the iron oxides catalysts. Results show that gamma-Fe2O3 is active in SCR at low temperatures, and Fe3O4 is apparently less active in SCR than gamma-Fe2O3, but Fe2O3 is also active in ammonia oxidation by O2 above 25 degrees C. Therefore, the optimal catalytic temperature zone in SCR on gamma-Fe2O3 includes 250 degrees C and adjacent temperature zone below it. Furthermore, a better NO conversion, which is 90%, is obtained at 250 degrees C on the gamma-Fe2O3 particle catalyst. In addition, chemisorption of NO on gamma-Fe2O3 is accelerated by assisted magnetic fields at 150-290 degrees C, thus the NO conversion is improved and higher NO removal efficiency of 95% is obtained at 250 degrees C. But the efficiency of NO removal decreases above 290 degrees C with the magnetic field. It is concluded that gamma-FeO3 catalyst is fit to be used in low-temperature SCR of NO with ammonia at 200-250 degrees C, which may suppress oxidation of ammonia and take advantage of positive effects by external magnetic fields.

  10. Lewis base activation of Lewis acids: catalytic, enantioselective addition of glycolate-derived silyl ketene acetals to aldehydes.

    Science.gov (United States)

    Denmark, Scott E; Chung, Won-Jin

    2008-06-20

    A catalytic system involving silicon tetrachloride and a chiral, Lewis basic bisphosphoramide catalyst is effective for the addition of glycolate-derived silyl ketene acetals to aldehydes. It was found that the sense of diastereoselectivity could be modulated by changing the size of the substituents on the silyl ketene acetals. In general, the trimethylsilyl ketene acetals derived from methyl glycolates with a large protecting group on the alpha-oxygen provide enantiomerically enriched alpha,beta-dihydroxy esters with high syn-diastereoselectivity, whereas the tert-butyldimethylsilyl ketene acetals derived from bulky esters of alpha-methoxyacetic acid provide enantiomerically enriched alpha,beta-dihydroxy esters with high anti-diastereoselecitvity.

  11. Solid-state charge-based device for control of catalytic carbon monoxide oxidation on platinum nanofilms using external bias and light.

    Science.gov (United States)

    Baker, L Robert; Hervier, Antoine; Kennedy, Griffin; Somorjai, Gabor A

    2012-05-09

    Using a Pt/Si catalytic nanodiode, we externally control the rate of CO oxidation on a Pt nanofilm. The catalytic reaction can be turned on and off by alternating between bias states of the device. Additionally, the reaction rate is sensitive to photocurrent induced by visible light. The effects of both bias and light show that negative charge on the Pt increases catalytic activity, while positive charge on the Pt decreases catalytic activity for CO oxidation.

  12. Simple, chemoselective, catalytic olefin isomerization.

    Science.gov (United States)

    Crossley, Steven W M; Barabé, Francis; Shenvi, Ryan A

    2014-12-01

    Catalytic amounts of Co(Sal(tBu,tBu))Cl and organosilane irreversibly isomerize terminal alkenes by one position. The same catalysts effect cycloisomerization of dienes and retrocycloisomerization of strained rings. Strong Lewis bases like amines and imidazoles, and labile functionalities like epoxides, are tolerated.

  13. Non-Catalytic and MgSO4 - Catalyst based Degradation of Glycerol in Subcritical and Supercritical Water Media

    Directory of Open Access Journals (Sweden)

    Mahfud Mahfud

    2011-02-01

    Full Text Available This research aims to study the glycerol degradation reaction in subcritical and supercritical water media. The degradation of glycerol into other products was performed both with sulphate salt catalysts and without catalyst. The reactant was made from glycerol and water with the mass ratio of 1:10. The experiments were carried out using a batch reactor at a constant pressure of 250 kgf/cm2, with the temperature range of 200-400oC, reaction time of 30 minutes, and catalyst mol ratio in glycerol of 1:10 and 1:8. The products of the non-catalytic glycerol degradation were acetaldehyde, methanol, and ethanol. The use of sulphate salt as catalyst has high selectivity to acetaldehyde and still allows the formation alcohol product in small quantities. The mechanism of ionic reaction and free radical reaction can occur at lower temperature in hydrothermal area or subcritical water. Conversion of glycerol on catalytic reaction showed a higher yield when compared with the reaction performed without catalyst

  14. Development of catalytic systems for selective hydrogenation and hydrogenolysis based on statistical planning methods coupled with kinetic studies

    Energy Technology Data Exchange (ETDEWEB)

    Zhorov, Yu.M.; Morozova, E.V.; Panchenkov, G.M.

    1979-01-01

    An efficient catalyst design methodology is described, which was used in developing an active and stable mixed oxide catalytic composition for selective hydrogenation of m-bonds under conditions excluding hydrogenolysis of C-C bonds. Catalysts of optimum composition, i.e., 40-50Vertical Bar3< CuO/25-30Vertical Bar3< NiO/20-35Vertical Bar3< SiO/sub 2/, and structure (20-30 A. average pore radius) can be prepared by coprecipitation of copper and nickel salts with silica gel powder in a sodium silicate solution at 90/sup 0/C. By using these catalysts, crotonaldehyde (CA) was hydrogenated to n-butanol in one stage with over 99Vertical Bar3< yields at 180/sup 0/C. The same catalyst was efficient in selective hydrogenation of acetylene (contained in relatively high concentrations in pyrolysis gases) to ethylene at 130/sup 0/C, hydrogenation of piperylene (a by-product in isoprene manufacture) to n-pentenes at 160/sup 0/C, with almost 100Vertical Bar3< selectivity, and in hydrogenolysis of C-S and C-N bonds at 290/sup 0/-370/sup 0/C. Catalytic hydrorefining of a gasoline fraction (105/sup 0/-180/sup 0/C bp) at 350/sup 0/C and 40 atm, reduced its sulfur content from 0.03Vertical Bar3< to 0.00001Vertical Bar3<, and completely removed nitrogen.

  15. Chitosan based polymer matrix with silver nanoparticles decorated multiwalled carbon nanotubes for catalytic reduction of 4-nitrophenol.

    Science.gov (United States)

    Alshehri, Saad M; Almuqati, Turki; Almuqati, Naif; Al-Farraj, Eida; Alhokbany, Norah; Ahamad, Tansir

    2016-10-20

    A novel catalyst for the reduction of 4-nitrophenol (4-NP) was prepared using carboxyl group-functionalized multiwalled carbon nanotubes (MWCNTs), polymer matrix, and silver nanoparticles (AgNPs). The AgNPs were prepared by the reduction of silver nitrate by trisodium citrate in the MWCNTs-polymer nanocomposite; the size of the synthesized AgNPs was found to be 3nm (average diameter). The synthesized nanocomposites were characterized using several analytical techniques. Ag@MWCNTs-polymer composite in the presence of sodium borohydride (NaBH4) in aqueous solution is an effective catalyst for the reduction of 4-NP. The apparent kinetics of reduction has a pseudo-first-order kinetics, and the rate constant and catalytic activity parameter were found to be respectively 7.88×10(-3)s(-1)and 11.64s(-1)g(-1). The MWCNTs-polymer nanocomposite renders stability to AgNPs against the environment and the reaction medium, which means that the Ag@MWCNTs-polymer composite can be re-used for many catalytic cycles.

  16. Catalytic activity and effect of modifiers on Ni-based catalysts for the dry reforming of methane

    Energy Technology Data Exchange (ETDEWEB)

    Barroso-Quiroga, Maria Martha; Castro-Luna, Adolfo Eduardo [Facultad de Ingenieria y Ciencias Economico-Sociales INTEQUI-CONICET-UNSL, Av. 25 de Mayo 384 (5730) Villa Mercedes (S.L.) (Argentina)

    2010-06-15

    Ni catalysts supported on different ceramic oxides (Al{sub 2}O{sub 3}, CeO{sub 2}, La{sub 2}O{sub 3}, ZrO{sub 2}) were prepared by wet impregnation. The catalytic behavior toward hydrogen production through the dry reforming of methane using a fixed-bed reactor was evaluated under certain experimental conditions, and the catalyst supported on ZrO{sub 2} showed the highest stable activity during the period of time studied. The catalyst supported on CeO{sub 2} has a relatively good activity, but shows signs of deactivation after a certain time during the reaction. This catalyst was chosen to be studied after the addition of 0.5 wt% Li and K as activity modifiers. The introduction of the alkaline metals produces a reduction of the catalytic activity but a better stability over the reactant conversion time. The reverse water-gas shift reaction influences the global system of reactions, and as the results indicate, should be considered near equilibrium. (author)

  17. 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.

  18. 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.  ……

  19. Progress in palladium-based catalytic systems for the sustainable synthesis of annulated heterocycles: a focus on indole backbones.

    Science.gov (United States)

    Platon, Mélanie; Amardeil, Régine; Djakovitch, Laurent; Hierso, Jean-Cyrille

    2012-05-21

    A survey highlighting the most recent palladium catalytic systems produced and their performances for progress in direct synthesis of indole backbones by heterocarbocyclization of reactive substrates is provided. The discussion is developed in relation with the principles of sustainable chemistry concerning atom and mass economy. In this respect, the general convergent character of the syntheses is of particular interest (one-pot, domino, cascade or tandem reactions), and the substrates accessibility and reactivity, together with the final waste production, are also important. This critical review clearly indicates that the development of ligand chemistry, mainly phosphines and carbenes, in the last few decades gave a significant impetus to powerful functionalization of indoles at virtually all positions of this ubiquitous backbone (118 references).

  20. Physico-chemical characterisations and catalytic performance of Ni-based catalyst systems for dry reforming of methane

    Energy Technology Data Exchange (ETDEWEB)

    Vlach, K.; Hoang, D.L.; Schneider, M.; Pohl, M.M.; Armbruster, U.; Martin, A. [Rostock Univ. (Germany). Leibniz-Institut fuer Katalyse e.V.

    2012-07-01

    In this study, ternary perovskite type oxides LaNi{sub x}Cu{sub 1-x}O{sub 3} (x = 0, 0.2, 0.5, 0.8, 1) were synthesized using NaOH and diethylenetriaminepentaacetic acid (H{sub 5}DTPA). The catalysts resulting from perovskite precursors exhibit catalytic activities for CO{sub 2} reforming of CH{sub 4} at 700 C that increase with a higher Ni content. Characterization methods showed that the activation led to formation of small metallic Ni/Cu particles. Methane and carbon dioxide conversions varied from 20 to 65% for CH{sub 4} and 3 to 58% for CO{sub 2}. Selectivities from 46 to 93% for CO and from 4 to 64% for H{sub 2} were obtained. (orig.)

  1. Enhanced catalytic activity of gold nanoparticles doped in a mesoporous organic gel based on polymeric phloroglucinol carboxylic acid-formaldehyde.

    Science.gov (United States)

    Yang, Han; Nagai, Keiji; Abe, Toshiyuki; Homma, Hirofumi; Norimatsu, Takayoshi; Ramaraj, Ramasamy

    2009-09-01

    Gold nanoparticles were supported by a phloroglucinolcarboxylic acid-formaldehyde (PF) gel, a new organic gel with a 30 nm spheroid-like structure. The surface area of the PF gel with gold nanoparticles was 550 m(2)/g. Gold nanoparticles supported on a PF gel exhibited catalytic activity in the reduction of 4-nitrophenol with a reaction rate constant of 7.4 x 10(-3) s(-1), which is high in the reported heterogeneous reaction system. The adsorption behavior of 4-nitrophenol into the gel support was observed by ultraviolet-visible absorption spectroscopy. Gold nanoparticles in the PF network were characterized by scanning electron microscopy, atomic force microscopy, and transmission electron microscopy observation. The high reduction rate would be attributed to the extraction and diffusion of the reactant through the pores of a PF gel support to encounter the highly dispersed gold nanoparticles on the surface and inside the material.

  2. Electrochemical sensor for catechol and dopamine based on a catalytic molecularly imprinted polymer-conducting polymer hybrid recognition element.

    Science.gov (United States)

    Lakshmi, Dhana; Bossi, Alessandra; Whitcombe, Michael J; Chianella, Iva; Fowler, Steven A; Subrahmanyam, Sreenath; Piletska, Elena V; Piletsky, Sergey A

    2009-05-01

    One of the difficulties with using molecularly imprinted polymers (MIPs) and other electrically insulating materials as the recognition element in electrochemical sensors is the lack of a direct path for the conduction of electrons from the active sites to the electrode. We have sought to address this problem through the preparation and characterization of novel hybrid materials combining a catalytic MIP, capable of oxidizing the template, catechol, with an electrically conducting polymer. In this way a network of "molecular wires" assists in the conduction of electrons from the active sites within the MIP to the electrode surface. This was made possible by the design of a new monomer that combines orthogonal polymerizable functionality; comprising an aniline group and a methacrylamide. Conducting films were prepared on the surface of electrodes (Au on glass) by electropolymerization of the aniline moiety. A layer of MIP was photochemically grafted over the polyaniline, via N,N'-diethyldithiocarbamic acid benzyl ester (iniferter) activation of the methacrylamide groups. Detection of catechol by the hybrid-MIP sensor was found to be specific, and catechol oxidation was detected by cyclic voltammetry at the optimized operating conditions: potential range -0.6 V to +0.8 V (vs Ag/AgCl), scan rate 50 mV/s, PBS pH 7.4. The calibration curve for catechol was found to be linear to 144 microM, with a limit of detection of 228 nM. Catechol and dopamine were detected by the sensor, whereas analogues and potentially interfering compounds, including phenol, resorcinol, hydroquinone, serotonin, and ascorbic acid, had minimal effect (< or = 3%) on the detection of either analyte. Non-imprinted hybrid electrodes and bare gold electrodes failed to give any response to catechol at concentrations below 0.5 mM. Finally, the catalytic properties of the sensor were characterized by chronoamperometry and were found to be consistent with Michaelis-Menten kinetics.

  3. Catalytic Oxidation of Phenol over Zeolite Based Cu/Y-5 Catalyst: Part 1: Catalyst Preparation and Characterization

    Directory of Open Access Journals (Sweden)

    K. Maduna Valkaj

    2015-01-01

    Full Text Available The necessity to remove organic pollutants from the industrial wastewater streams has forced the development of new technologies that can produce better results in terms of pollutant removal and process efficiency in combination with low investment and operating costs. One of the new emerging processes with a potential to fulfil these demands is catalytic wet peroxide oxidation, commonly known as the CWPO process. The oxidative effect of the hydrogen peroxide is intensified by the addition of a heterogeneous catalyst that can reduce the operating conditions to atmospheric pressure and temperatures below 383 K. Zeolites, among others, are especially appealing as catalysts for selective oxidation processes due to their unique characteristics such as shape selectivity, thermal and chemical stability, and benign effect on nature and the living world. In this work, catalytic activity, selectivity and stability of Cu/Y-5 zeolite in phenol oxidation with hydrogen peroxide was examined. Catalyst samples were prepared by ion exchange method of the protonic form of commercial zeolite. The catalysts were characterized with powder X-ray diffraction (XRD, scanning electron microscopy (SEM, and AAS elemental analysis, while the adsorption techniques were used for the measurement of the specific surface area. The catalytic tests were carried out in a stainless steel Parr reactor in batch operation mode at the atmospheric pressure and in the temperature range from 323 to 353 K. The catalyst was prepared in powdered form and the mass fraction of the active metal component on the zeolite was 3.46 %. The initial concentration of phenol solution was equal to 0.01 mol dm−3 and the concentration of hydrogen peroxide ranged from 0.01 to 0.10 mol dm−3. The obtained experimental data was tested to a proposed kinetic model for phenol oxidation r = k1 cF cVP and hydrogen peroxide decomposition rHP = k2 cHP. The kinetic parameters were estimated using the Nelder

  4. The catalytic properties of Ce-based catalysts for H{sub 2}S selective oxidation with SO{sub 2}

    Energy Technology Data Exchange (ETDEWEB)

    No-Kuk Park; Dong Cheul Han; Gi Bo Han; Tae Jin Lee; Si Ok Ryu [Yeungnam University, Daedong Kyongsan (Republic of Korea). National Research Laboratory, School of Chemical Engineering & Technology

    2007-07-01

    Claus reaction was applied for the removal of H{sub 2}S contained in the gasified coal gas. Major components of a flue gas exiting from a gasifier in IGCC system are CO and H{sub 2}. Since the considerable moisture content is present in the gasified coal gas, the effects of reducing gases and H{sub 2}O on the catalytic activity were investigated over Ce-based catalysts. A series of experiments were carried out in a tubular quartz reactor packed with 0.4 grams of Ce-based composite catalysts in order to investigate the characteristics of Claus reaction. Concentrations H{sub 2}S and SO{sub 2} were 10000 ppm and 5000 ppm, respectively. Temperature was fixed at 200 for the experiments and space velocity was maintained in 30000 ml/g-cat.h. In order to find out the catalytic reaction mechanism, the reactivity test was performed in a packed-bed reactor. About 1.5 gram of Ce-based catalyst was filled into the reactor. 5000 ppm of H{sub 2}S was fed into the reactor at the rate of 100 ml/min. The concentration of H{sub 2}S was monitored at the outlet of reactor. In conclusions, power of the lattice oxygen for the oxidation of H{sub 2}S and the oxidation ability of the Ce-based catalyst for the reduction of SO{sub 2} were excellent. It was confirmed that Claus reaction over the Ce-based catalysts was carried out by the redox mechanism. 20 refs., 7 figs., 1 tab.

  5. Nickel-based xerogel catalysts: Synthesis via fast sol-gel method and application in catalytic hydrogenation of p-nitrophenol to p-aminophenol

    Science.gov (United States)

    Feng, Jin; Wang, Qiang; Fan, Dongliang; Ma, Lirong; Jiang, Deli; Xie, Jimin; Zhu, Jianjun

    2016-09-01

    In order to investigate the roles of three-dimensional network structure and calcium on Ni catalysts, the Ni, Ni-Al2O3, Ni-Ca-Al2O3 xerogel catalysts were successfully synthesized via the fast sol-gel process and chemical reduction method. The crystal structure of three different catalysts was observed with X-ray powder diffraction (XRD). Transmission electron microscopy (TEM), scanning electron microscopy (SEM) and nitrogen adsorption-desorption were employed to investigate the role of network structure of xerogel catalysts and the size distribution of Ni nanoparticles. The catalyst composition was determined by inductively coupled plasma-optical emission spectrometry (ICP-OES) measurement and energy-dispersive X-ray spectroscopy (EDS). Temperature-programmed reduction (TPR) experiments were carried out to investigate the reducibility of nickel species and the interaction between nickel species and alumina. The catalytic hydrogenation of p-nitrophenol to p-aminophenol was investigated over the prepared nickel-based xerogel catalysts. The conversion of p-nitrophenol was monitored by UV spectrophotometry and high performance liquid chromatography (HPLC). The results show that the catalysts are highly selective for the conversion of p-nitrophenol to p-aminophenol and the order of catalytic activities of the catalysts is Ni < Ni-Al2O3 < Ni-Ca-Al2O3. The catalysts were recycled and were used to evaluate the reutilization.

  6. Syntheses of Some New Group 4 non-Cp Complexes Bearing Schiff-base,Thiophene Diamide Ligands Respectively and Their Catalytic Activities for α-Olefin Polymerization

    Institute of Scientific and Technical Information of China (English)

    HUANG, Ji-Ling(黄吉玲); LIAN, Bing(廉兵); YONG, Li(雍莉); QIAN, Yan-Long(钱延龙)

    2004-01-01

    Totally sixteen new titanium and zirconium non-Cp complexes supported by Schiff-base, or thiophene diamide ligands have been synthesized. The complexes are obtained by the reaction of M(OPr-i)4 (M=Ti, Zr) with the corresponding Schiff-base ligand in 1 :1 molar ratio in good yield. The thiophene diamide titanium complex has been prepared from trimethylsilyl amine [N,S,N] ligand and TiCl4 in toluene at 120 ℃. All complexes are well characterized by 1H NMR, IR, MS and elemental analysis. When activated by excess methylaluminoxane (MAO), complexes show moderate catalytic activity for ethylene polymerization, and complex 1f (R1 =CH3, R2=Br) exhibits the highest activity for ethylene and styrene polymerization. When the complexes were preactivated by triethylaluminum (TEA), both polymerization activities and syndiotacticity of the polymers were greatly improved.

  7. Rare earth metal doped CeO2-based catalytic materials for diesel soot oxidation at lower temperatures

    Institute of Scientific and Technical Information of China (English)

    A Rangaswamy; Putla Sudarsanam; Benjaram M Reddy

    2015-01-01

    In this work, the influence of trivalent rare-earth dopants (Sm and La) on the structure-activity properties of CeO2 was thor-oughly studied for diesel soot oxidation. For this, an optimized 40%of Sm and La was incorporated into the CeO2 using a facile co-precipitation method from ultra-high dilute aqueous solutions. A systematic physicochemical characterization was carried out using X-ray diffraction (XRD), transmission electron microscopy (TEM), Brumauer-Emmett-teller method (BET) surface area, X-ray pho-toelectron spectroscopy (XPS), Raman, and H2-temperature programmed reduction (TPR) techniques. The soot oxidation efficiency of the catalysts was investigated using a thermogravimetric method. The XRD results suggested the formation of nanocrystalline sin-gle phase CeO2-Sm2O3 and CeO2-La2O3 solid solutions. The Sm-and La-doped CeO2 materials exhibited smaller crystallite size and higher BET surface area compared with the pure CeO2. Owing to the difference in the oxidation states of the dopants (Sm3+and La3+) and the Ce4+, a number of oxygen vacancies were generated in CeO2-Sm2O3 and CeO2-La2O3 samples. The H2-TPR studies evidenced the improved reducible nature of the CeO2-Sm2O3 and CeO2-La2O3 samples compared with the CeO2. It was found that the addition of Sm and La to the CeO2 outstandingly enhanced its catalytic efficiency for the oxidation of diesel soot. The observed 50%soot con-version temperatures for the CeO2-Sm2O3, CeO2-La2O3 and CeO2 were~790, 843 and 864 K (loose contact), respectively, and similar activity order was also found under the tight contact condition. The high soot oxidation efficacy of the CeO2-Sm2O3 sample was at-tributed to numerous catalytically favourable properties, like smaller crystallite size, larger surface area, abundant oxygen vacancies, and superior reducible nature.

  8. Use of Metallopeptide Based Mimics Demonstrates That the Metalloprotein Nitrile Hydratase Requires Two Oxidized Cysteinates for Catalytic Activity

    Energy Technology Data Exchange (ETDEWEB)

    Shearer, J.; Callan, P; Amie, J

    2010-01-01

    Nitrile hydratases (NHases) are non-heme Fe{sup III} or non-corrin Co{sup III} containing metalloenzymes that possess an N{sub 2}S{sub 3} ligand environment with nitrogen donors derived from amidates and sulfur donors derived from cysteinates. A closely related enzyme is thiocyanate hydrolase (SCNase), which possesses a nearly identical active-site coordination environment as CoNHase. These enzymes are redox inactive and perform hydrolytic reactions; SCNase hydrolyzes thiocyanate anions while NHase converts nitriles into amides. Herein an active CoNHase metallopeptide mimic, [Co{sup III}NHase-m1] (NHase-m1 = AcNH-CCDLP-CGVYD-PA-COOH), that contains Co{sup III} in a similar N{sub 2}S{sub 3} coordination environment as CoNHase is reported. [Co{sup III}NHase-m1] was characterized by electrospray ionization-mass spectrometry (ESI-MS), gel-permeation chromatography (GPC), Co K-edge X-ray absorption spectroscopy (Co-S: 2.21 {angstrom}; Co-N: 1.93 {angstrom}), vibrational, and optical spectroscopies. We find that [Co{sup III}NHase-m1] will perform the catalytic conversion of acrylonitrile into acrylamide with up to 58 turnovers observed after 18 h at 25 C (pH 8.0). FTIR data used in concert with calculated vibrational data (mPWPW91/aug-cc-TZVPP) demonstrates that the active form of [Co{sup III}NHase-m1] has a ligated SO{sub 2} (? = 1091 cm{sup -1}) moiety and a ligated protonated SO(H) (? = 928 cm{sup -1}) moiety; when only one oxygenated cysteinate ligand (i.e., a mono-SO{sub 2} coordination motif) or the bis-SO{sub 2} coordination motif are found within [Co{sup III}NHase-m1] no catalytic activity is observed. Calculations of the thermodynamics of ligand exchange (B3LYP/aug-cc-TZVPP) suggest that the reason for this is that the SO{sub 2}/SO(H) equatorial ligand motif promotes both water dissociation from the Co{sup III}-center and nitrile coordination to the Co{sup III}-center. In contrast, the under- or overoxidized motifs will either strongly favor a five coordinate Co

  9. Synthesis, Thermal, Electrical and Catalytic Studies of Some Transition Metal Polychelates of Bis-bidentate Schiff Base

    Institute of Scientific and Technical Information of China (English)

    BANSOD Ashish; ASWAR Anand

    2007-01-01

    Polychelates of Mn(Ⅱ),Fe(Ⅱ),Co(Ⅱ), Ni(Ⅱ),Cu(Ⅱ),Zn(Ⅱ) and Cd(Ⅱ) with the bis salen-type ligand derivedfrom 4,4'-bis[(salicylaldehyde-5)azo]biphenyl and 1,4-diaminobutane have been synthesized.All the polychelates have been characterized by elemental analysis,magnetic susceptibility measurements,IR,electronic spectra and thermogravimetric studies.All the complexes isolated in solid state are dark coloured and insoluble in water and common organic solvents.The ligand behaves as a bis-bidentate molecule coordinating through the phenolic oxygen and azomethine nitrogen atoms.The thermal decomposition of these metal complexes was investigated by thermogravimetric analysis and data have been analyzed for kinetic parameters using Broido equation.The solid-state electrical conductivity of the ligand and its polychelates in the form of compressed pellet was studied in the temperature range from 313 to 413 K.All the polychelates were found to show semiconducting nature.The Mn(Ⅱ),Fe(Ⅱ),Co(Ⅱ) and Ni(Ⅱ) polychelates have been assessed for the catalytic epoxidation of styrene.

  10. Significantly Improved Catalytic Performance of Ni-Based MgO Catalyst in Steam Reforming of Phenol by Inducing Mesostructure

    Directory of Open Access Journals (Sweden)

    Xiaoxuan Yang

    2015-10-01

    Full Text Available A Ni/meso-MgO catalyst with high surface area and small Ni nanoparticles was synthesized and investigated for hydrogen production by steam reforming of phenol for the first time. Compared to conventional Ni/MgO, the Ni/meso-MgO catalyst showed higher catalytic activity and stability. X-ray Diffraction, N2 adsorption, hydrogen temperature programmed reduction, transmission electron microscopy and thermal gravimetry results indicated that the Ni/meso-MgO catalyst had higher surface area than Ni/MgO and Ni particles of Ni/meso-MgO were narrowly distributed in the range of 5~6 nm with an average size of 5.3 nm, while Ni particles of Ni/MgO were in the range of 6~10 nm with an average size of 7.92 nm. The small and uniform Ni nanoparticles in Ni/meso-MgO were attributed to the high surface area and the confinement effect of the mesoporous structure of meso-MgO, which could effectively limit the growth of the active metal and stabilize Ni particles during the procedure of NiO reduction. The mesoporous structure of Ni/meso-MgO also played an important role in suppressing Ni nanoparticle sintering and carbon deposition during the steam reforming of phenol reaction.

  11. Comparison and analysis of zinc and cobalt-based systems as catalytic entities for the hydration of carbon dioxide.

    Directory of Open Access Journals (Sweden)

    Edmond Y Lau

    Full Text Available In nature, the zinc metalloenzyme carbonic anhydrase II (CAII efficiently catalyzes the conversion of carbon dioxide (CO2 to bicarbonate under physiological conditions. Many research efforts have been directed towards the development of small molecule mimetics that can facilitate this process and thus have a beneficial environmental impact, but these efforts have met very limited success. Herein, we undertook quantum mechanical calculations of four mimetics, 1,5,9-triazacyclododedacane, 1,4,7,10-tetraazacyclododedacane, tris(4,5-dimethyl-2-imidazolylphosphine, and tris(2-benzimidazolylmethylamine, in their complexed form either with the Zn(2+ or the Co(2+ ion and studied their reaction coordinate for CO2 hydration. These calculations demonstrated that the ability of the complex to maintain a tetrahedral geometry and bind bicarbonate in a unidentate manner were vital for the hydration reaction to proceed favorably. Furthermore, these calculations show that the catalytic activity of the examined zinc complexes was insensitive to coordination states for zinc, while coordination states above four were found to have an unfavorable effect on product release for the cobalt counterparts.

  12. Performance of supported catalysts based on a new copper vanadate-type precursor for catalytic oxidation of toluene

    Energy Technology Data Exchange (ETDEWEB)

    Palacio, L.A. [Grupo Catalizadores y Adsorbentes, Universidad de Antioquia, A.A. 1226 - Medellin (Colombia); Silva, E.R.; Catalao, R. [IBB-Institute for Biotechnology and Bioengineering, Instituto Superior Tecnico, Av. Rovisco Pais, 1049-001 Lisboa (Portugal); Silva, J.M. [IBB-Institute for Biotechnology and Bioengineering, Instituto Superior Tecnico, Av. Rovisco Pais, 1049-001 Lisboa (Portugal); Instituto Superior Engenharia de Lisboa, Departamento de Engenharia Quimica. Av. Cons. Emidio Navarro, 1959-007 Lisboa (Portugal); Hoyos, D.A. [Grupo Catalizadores y Adsorbentes, Universidad de Antioquia, A.A. 1226 - Medellin (Colombia); Ribeiro, F.R. [IBB-Institute for Biotechnology and Bioengineering, Instituto Superior Tecnico, Av. Rovisco Pais, 1049-001 Lisboa (Portugal); Ribeiro, M.F. [IBB-Institute for Biotechnology and Bioengineering, Instituto Superior Tecnico, Av. Rovisco Pais, 1049-001 Lisboa (Portugal)], E-mail: filipa.ribeiro@ist.utl.pt

    2008-05-01

    A new copper vanadate precursor with the formula NH{sub 4}[Cu{sub 2.5}V{sub 2}O{sub 7}(OH){sub 2}].H{sub 2}O was synthesized and deposited on two different supports, ZSM-5 and amorphous SiO{sub 2}, by a hydrothermal method or by mechanical mixture. The catalytic behaviour was evaluated in the total oxidation of toluene and the characterization was performed by H{sub 2}-temperature-programmed reduction (H{sub 2}-TPR), thermogravimetric analysis, elemental analysis, UV-vis diffuse reflectance spectroscopy and X-ray diffraction. It was found that the copper vanadate phase comprises two mixed oxides, one of them crystalline, the Ziesite phase, and the other one amorphous. The supported catalysts presented a content of copper vanadate phase of about 9-11 wt.%. The copper vanadate deposited on ZSM-5 by the hydrothermal method evidences the best performance in the oxidation of toluene. This behaviour can be associated with the smaller size and higher dispersion of the particles on the support, which was confirmed by their better reducibility and higher band gap energy value compared with the other series of studied catalysts.

  13. Catalytic combustor for hydrogen

    Energy Technology Data Exchange (ETDEWEB)

    Mercea, J.; Grecu, E.; Fodor, T.; Kreibik, S.

    1982-01-01

    The performance of catalytic combustors for hydrogen using platinum-supported catalysts is described. Catalytic plates of different sizes were constructed using fibrous and ceramic supports. The temperature distribution as well as the reaction efficiency as a function of the fuel input rate was determined, and a comparison between the performances of different plates is discussed.

  14. Catalytic wet air oxidation of bisphenol A solution in a batch-recycle trickle-bed reactor over titanate nanotube-based catalysts.

    Science.gov (United States)

    Kaplan, Renata; Erjavec, Boštjan; Senila, Marin; Pintar, Albin

    2014-10-01

    Catalytic wet air oxidation (CWAO) is classified as an advanced oxidation process, which proved to be highly efficient for the removal of emerging organic pollutant bisphenol A (BPA) from water. In this study, BPA was successfully removed in a batch-recycle trickle-bed reactor over bare titanate nanotube-based catalysts at very short space time of 0.6 min gCAT g(-1). The as-prepared titanate nanotubes, which underwent heat treatment at 600 °C, showed high activity for the removal of aqueous BPA. Liquid-phase recycling (5- or 10-fold recycle) enabled complete BPA conversion already at 200 °C, together with high conversion of total organic carbon (TOC), i.e., 73 and 98 %, respectively. The catalyst was chemically stable in the given range of operating conditions for 189 h on stream.

  15. Near-Infrared- and Visible-Light-Enhanced Metal-Free Catalytic Degradation of Organic Pollutants over Carbon-Dot-Based Carbocatalysts Synthesized from Biomass.

    Science.gov (United States)

    Wang, Hui; Zhuang, Jianqin; Velado, David; Wei, Zengyan; Matsui, Hiroshi; Zhou, Shuiqin

    2015-12-23

    Cost-efficient nanoparticle carbocatalysts composed of fluorescent carbon dots (CDs) embedded in carbon matrix were synthesized via one-step acid-assisted hydrothermal treatment (200 °C) of glucose. These as-synthesized CD-based carbocatalysts have excellent photoluminescence (PL) properties over a broad range of wavelengths and the external visible or NIR irradiation on the carbocatalysts could produce electrons to form electron-hole (e(-)-h(+)) pairs on the surface of carbocatalysts. These restant electron-hole pairs will react with the adsorbed oxidants/reducers on the surface of the CD-based carbocatalysts to produce active radicals for reduction of 4-nitrophenol and degradation of dye molecules. Moreover, the local temperature increase over CD-based carbocatalyst under NIR irradiation can enhance the electron transfer rate between the organic molecules and CD-based carbocatalysts, thus obviously increase the catalytic activity of the CD-based carbocatalyst for the reduction of 4-nitrophenol and the degradation of dye molecules. Such a type of CD-based carbocatalysts with excellent properties and highly efficient metal-free photocatalytic activities is an ideal candidate as photocatalysts for the reduction of organic pollutants under visible light and NIR radiation.

  16. Catalytic Wittig and aza-Wittig reactions

    Directory of Open Access Journals (Sweden)

    Zhiqi Lao

    2016-11-01

    Full Text Available This review surveys the literature regarding the development of catalytic versions of the Wittig and aza-Wittig reactions. The first section summarizes how arsenic and tellurium-based catalytic Wittig-type reaction systems were developed first due to the relatively easy reduction of the oxides involved. This is followed by a presentation of the current state of the art regarding phosphine-catalyzed Wittig reactions. The second section covers the field of related catalytic aza-Wittig reactions that are catalyzed by both phosphine oxides and phosphines.

  17. Synthesis and Characterization of Two Novel Organic-Inorganic Compounds Based on Tetrahexyl and Tetraheptyl Ammonium Ions and the Preyssler Anion and Their Catalytic Activities in the Synthesis of 4-Aminopyrazolo[3,4-d]- Pyrimidines

    Directory of Open Access Journals (Sweden)

    Fatemeh Farrash Bamoharram

    2010-04-01

    Full Text Available Two novel organic–inorganic compounds based on tetrahexylammonium (THA and tetraheptylammonium (THPA ions and the Preyssler anion, [NaP5W30O110]14-, were synthesized and formulated as (THA7.7H6.3 [NaP5W30O110] (A and (THPA7.5 H6.5[N aP5W30O110] (B. The synthesized compounds were characterized by IR, UV, and TGA and used for the catalytic synthesis of 4-aminopyrazolo[3,4,-d]pyrimidine derivatives 2a-2d. Our findings showed efficient catalytic activities for A and B.

  18. Catalytic Radical Domino Reactions in Organic Synthesis

    Science.gov (United States)

    Sebren, Leanne J.; Devery, James J.; Stephenson, Corey R.J.

    2014-01-01

    Catalytic radical-based domino reactions represent important advances in synthetic organic chemistry. Their development benefits synthesis by providing atom- and step-economical methods to complex molecules. Intricate combinations of radical, cationic, anionic, oxidative/reductive, and transition metal mechanistic steps result in cyclizations, additions, fragmentations, ring-expansions, and rearrangements. This Perspective summarizes recent developments in the field of catalytic domino processes. PMID:24587964

  19. 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...

  20. 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

  1. Catalytic Functions of Standards

    NARCIS (Netherlands)

    K. Blind (Knut)

    2009-01-01

    textabstractThe three different areas and the examples have illustrated several catalytic functions of standards for innovation. First, the standardisation process reduces the time to market of inventions, research results and innovative technologies. Second, standards themselves promote the diffusi

  2. Catalytic Synthesis Lactobionic Acid

    Directory of Open Access Journals (Sweden)

    V.G. Borodina

    2014-07-01

    Full Text Available Gold nanoparticles are obtained, characterized and deposited on the carrier. Conducted catalytic synthesis of lactobionic acid from lactose. Received lactobionic acid identify on the IR spectrum.

  3. 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.

  4. Catalytic distillation process

    Science.gov (United States)

    Smith, L.A. Jr.

    1982-06-22

    A method is described 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.

  5. Experimental investigation of the catalytic decomposition and combustion characteristics of a non-toxic ammonium dinitramide (ADN)-based monopropellant thruster

    Science.gov (United States)

    Chen, Jun; Li, Guoxiu; Zhang, Tao; Wang, Meng; Yu, Yusong

    2016-12-01

    Low toxicity ammonium dinitramide (ADN)-based aerospace propulsion systems currently show promise with regard to applications such as controlling satellite attitude. In the present work, the decomposition and combustion processes of an ADN-based monopropellant thruster were systematically studied, using a thermally stable catalyst to promote the decomposition reaction. The performance of the ADN propulsion system was investigated using a ground test system under vacuum, and the physical properties of the ADN-based propellant were also examined. Using this system, the effects of the preheating temperature and feed pressure on the combustion characteristics and thruster performance during steady state operation were observed. The results indicate that the propellant and catalyst employed during this work, as well as the design and manufacture of the thruster, met performance requirements. Moreover, the 1 N ADN thruster generated a specific impulse of 223 s, demonstrating the efficacy of the new catalyst. The thruster operational parameters (specifically, the preheating temperature and feed pressure) were found to have a significant effect on the decomposition and combustion processes within the thruster, and the performance of the thruster was demonstrated to improve at higher feed pressures and elevated preheating temperatures. A lower temperature of 140 °C was determined to activate the catalytic decomposition and combustion processes more effectively compared with the results obtained using other conditions. The data obtained in this study should be beneficial to future systematic and in-depth investigations of the combustion mechanism and characteristics within an ADN thruster.

  6. In situ FTIR spectroscopic assessment of methylbutynol catalytic conversion products in relation to the surface acid-base properties of systematically modified aluminas

    Science.gov (United States)

    Mekhemer, Gamal A. H.; Zaki, Mohamed I.

    2016-10-01

    The present investigation was designed to assess the credibility of methylbutynol (MBOH) as an infrared (IR) reactive probe molecule for surface acid-base properties of metal oxides. Accordingly, pure alumina was systematically modified with varied amounts (0.5-10 wt.%) of K+ or SO42 - additives. Then, the influence of nature and amount of the additive on the following alumina properties were examined: (i) bulk composition and structure by X-ray powder diffractometry and ex-situ IR spectroscopy, (ii) surface area and net charge by N2 sorptiometry and pH-metry, respectively, and (iii) nature and strength of exposed surface acid sites by in-situ IR spectroscopy of adsorbed pyridine at ambient and higher temperatures. Results obtained were correlated with IR-identified product distribution of MBOH catalytic decomposition/conversion at 200 °C. It is thereby concluded that MBOH is superior to conventional IR inactive probe molecules in gauging sensitively the prevailing acid or base character, availability of base sites, relative population of Bronsted to Lewis acid sites, and strength and reactivity of the sites exposed on metal oxide surfaces. Hence, all that is needed to get this information is to handle IR spectra taken from the gas phase, a task that is experimentally much more accessible than taking spectra from adsorbed species of irreactive probe molecules.

  7. Template electrodeposition of catalytic nanomotors.

    Science.gov (United States)

    Wang, Joseph

    2013-01-01

    The combination of nanomaterials with electrode materials has opened new horizons in electroanalytical chemistry, and in electrochemistry in general. Over the past two decades we have witnessed an enormous activity aimed at designing new electrochemical devices based on nanoparticles, nanotubes or nanowires, and towards the use of electrochemical routes--particularly template-assisted electrodeposition--for preparing nanostructured materials. The power of template-assisted electrochemical synthesis is demonstrated in this article towards the preparation and the realization of self-propelled catalytic nanomotors, ranging from Pt-Au nanowire motors to polymer/Pt microtube engines. Design considerations affecting the propulsion behavior of such catalytic nanomotors are discussed along with recent bioanalytical and environmental applications. Despite recent major advances, artificial nanomotors have a low efficiency compared to their natural counterparts. Hopefully, the present Faraday Discussion will stimulate other electrochemistry teams to contribute to the fascinating area of artificial nanomachines.

  8. Catalytic distillation structure

    Science.gov (United States)

    Smith, L.A. Jr.

    1984-04-17

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

  9. 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.

  10. A study on naphtha catalytic reforming reactor simulation and analysis

    Institute of Scientific and Technical Information of China (English)

    LIANG Ke-min; GUO Hai-yan; PAN Shi-wei

    2005-01-01

    A naphtha catalytic reforming unit with four reactors 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 reactions characteristics based on idealizing the complex naphtha mixture by representing the paraffin, naphthene, and aromatic groups by single compounds. The simulation results based above models agree very well with actual operation unit data.

  11. Base Catalytic Approach: A Promising Technique for the Activation of Biochar for Equilibrium Sorption Studies of Copper, Cu(II Ions in Single Solute System

    Directory of Open Access Journals (Sweden)

    Sharifah Bee Abdul Hamid

    2014-04-01

    Full Text Available This study examines the feasibility of catalytically pretreated biochar derived from the dried exocarp or fruit peel of mangostene with Group I alkali metal hydroxide (KOH. The pretreated char was activated in the presence of carbon dioxide gas flow at high temperature to upgrade its physiochemical properties for the removal of copper, Cu(II cations in single solute system. The effect of three independent variables, including temperature, agitation time and concentration, on sorption performance were carried out. Reaction kinetics parameters were determined by using linear regression analysis of the pseudo first, pseudo second, Elovich and intra-particle diffusion models. The regression co-efficient, R2 values were best for the pseudo second order kinetic model for all the concentration ranges under investigation. This implied that Cu(II cations were adsorbed mainly by chemical interactions with the surface active sites of the activated biochar. Langmuir, Freundlich and Temkin isotherm models were used to interpret the equilibrium data at different temperature. Thermodynamic studies revealed that the sorption process was spontaneous and endothermic. The surface area of the activated sample was 367.10 m2/g, whereas before base activation, it was only 1.22 m2/g. The results elucidated that the base pretreatment was efficient enough to yield porous carbon with an enlarged surface area, which can successfully eliminate Cu(II cations from waste water.

  12. A catalytically and genetically optimized beta-lactamase-matrix based assay for sensitive, specific, and higher throughput analysis of native henipavirus entry characteristics.

    Science.gov (United States)

    Wolf, Mike C; Wang, Yao; Freiberg, Alexander N; Aguilar, Hector C; Holbrook, Michael R; Lee, Benhur

    2009-07-31

    Nipah virus (NiV) and Hendra virus (HeV) are the only paramyxoviruses requiring Biosafety Level 4 (BSL-4) containment. Thus, study of henipavirus entry at less than BSL-4 conditions necessitates the use of cell-cell fusion or pseudotyped reporter virus assays. Yet, these surrogate assays may not fully emulate the biological properties unique to the virus being studied. Thus, we developed a henipaviral entry assay based on a beta-lactamase-Nipah Matrix (betala-M) fusion protein. We first codon-optimized the bacterial betala and the NiV-M genes to ensure efficient expression in mammalian cells. The betala-M construct was able to bud and form virus-like particles (VLPs) that morphologically resembled paramyxoviruses. betala-M efficiently incorporated both NiV and HeV fusion and attachment glycoproteins. Entry of these VLPs was detected by cytosolic delivery of betala-M, resulting in enzymatic and fluorescent conversion of the pre-loaded CCF2-AM substrate. Soluble henipavirus receptors (ephrinB2) or antibodies against the F and/or G proteins blocked VLP entry. Additionally, a Y105W mutation engineered into the catalytic site of betala increased the sensitivity of our betala-M based infection assays by 2-fold. In toto, these methods will provide a more biologically relevant assay for studying henipavirus entry at less than BSL-4 conditions.

  13. A catalytically and genetically optimized β-lactamase-matrix based assay for sensitive, specific, and higher throughput analysis of native henipavirus entry characteristics

    Directory of Open Access Journals (Sweden)

    Holbrook Michael R

    2009-07-01

    Full Text Available Abstract Nipah virus (NiV and Hendra virus (HeV are the only paramyxoviruses requiring Biosafety Level 4 (BSL-4 containment. Thus, study of henipavirus entry at less than BSL-4 conditions necessitates the use of cell-cell fusion or pseudotyped reporter virus assays. Yet, these surrogate assays may not fully emulate the biological properties unique to the virus being studied. Thus, we developed a henipaviral entry assay based on a β-lactamase-Nipah Matrix (βla-M fusion protein. We first codon-optimized the bacterial βla and the NiV-M genes to ensure efficient expression in mammalian cells. The βla-M construct was able to bud and form virus-like particles (VLPs that morphologically resembled paramyxoviruses. βla-M efficiently incorporated both NiV and HeV fusion and attachment glycoproteins. Entry of these VLPs was detected by cytosolic delivery of βla-M, resulting in enzymatic and fluorescent conversion of the pre-loaded CCF2-AM substrate. Soluble henipavirus receptors (ephrinB2 or antibodies against the F and/or G proteins blocked VLP entry. Additionally, a Y105W mutation engineered into the catalytic site of βla increased the sensitivity of our βla-M based infection assays by 2-fold. In toto, these methods will provide a more biologically relevant assay for studying henipavirus entry at less than BSL-4 conditions.

  14. Stability of catalytic foam diesel-soot filters based on Cs{sub 2}O, MoO{sub 3}, and Cs{sub 2}SO{sub 4} molten-salt catalysts

    Energy Technology Data Exchange (ETDEWEB)

    Van Setten, B.A.A.L.; Spitters, C.G.M.; Bremmer, J.; Mulders, A.M.M.; Makkee, M.; Moulijn, J.A. [Section Reactor and Catalysis Engineering, Faculty of Applied Sciences, Delft University of Technology, Julianalaan 136, 2628 BL Delft (Netherlands)

    2003-06-10

    The durability of catalytic alumina and zirconia-toughened mullite ceramic foam diesel-soot filters was tested by exposing them to severe, artificial exhaust conditions. The catalytic performance, composition, and mechanical strength were constantly monitored. It was concluded that the mechanical strength of the catalytic filters may be reduced by an interaction of the catalyst with certain compounds of ceramic filters. In practice, it should be possible to minimize the effect by carefully controlling the composition of the ceramic filter. For instance, the presence of phosphorous in alumina-based filters support should be avoided. The stability of the current catalyst phases, based on Cs{sub 2}O, MoO{sub 3}, and Cs{sub 2}SO{sub 4}, is too low for application. Due to partial evaporation, emission of catalyst compounds into the environment is likely and when that happens significant deactivation of the catalytic phase is unavoidable. The catalyst was also found to be soluble in water, which might be disastrous in the case of condensation occurring in the exhaust pipe.

  15. SYNTHESIS, CHARACTERIZATION AND CATALYTIC ACTIVITY OF N,N'-BIS(3-ALLYL SALICYLIDENE)ETHYLENEDIAMINE COBALT(II) SCHIFF BASE COMPLEX ANCHORED ON A NEW POLYMER SUPPORT

    Institute of Scientific and Technical Information of China (English)

    K.C. Gupta; H.K. Abdulkadir; S. Chand

    2004-01-01

    A new chelating polymer support has been prepared by suspension copolymeriz a tion of synthesized N,N'-bis(3-allyl salicylidene)ethylenediamine monomer Schiff base (N,N'-BSEDA) with styrene (St) and divinylbenzene (DVB) using azobisisobutyronitrile (AIBN) as initiator in the presence of poly(vinyl alcohol). The content and complexation ability of monomer Schiff base (N,N'-BSEDA) for cobalt(II) ions in prepared crosslinked polymer beads have shown dependence on the amount of DVB used in reaction mixture. The amount of monomer Schiff base (N,N'-BSEDA) in crosslinked beads showed a substantial decreasing trend at high concentration of DVB in the reaction mixture (> 1.5 mol dm-3), hence the efficiency of complexation (EC%) and cobalt(II) ion loading (EL%) of polymer beads showed a decreasing trend. The structure of monomer Schiff base (N,N'-BSEDA) and its cobalt(II) complex on polymer support was elucidated by IR, UV and magnetic measurements. The catalytic activity of polymer bound cobalt(Ⅱ) Schiff base complex was evaluated by analyzing kinetic data of decomposition of hydrogen peroxide in the presence of either supported cobalt (II) complex or free cobalt(II) complex. The activation energy for the decomposition of hydrogen peroxide by polymer supported cobalt(II)complex was found to be low (33.37 kJ mol-l) in comparison with unsupported cobalt(II) complex (56.35 kJ mol-1). On the basis of experimental observations, reaction steps are proposed and a suitable rate expression derived.

  16. The catalytic effect of the NH3 base on the chemical events in the caryolene-forming carbocation cascade.

    Science.gov (United States)

    Ortega, Daniela E; Nguyen, Quynh Nhu N; Tantillo, Dean J; Toro-Labbé, Alejandro

    2016-05-05

    Caryolene formation occur asynchronously in a concerted way through carbocationic rearrangements involving the generation of a secondary or a tertiary carbocation whether the reaction proceeds in the absence or in the presence of NH3 , respectively. Both caryolene formation mechanisms are analyzed within the general framework of the reaction force; the reaction force constant is used to gain insights into the synchronicity of the mechanisms and the reaction electronic flux helps to characterize the electronic activity taking place during the reaction. DFT calculations at the B3LYP/6-31+G(d,p) level show a clear difference in the mechanisms of the base promoted or base free caryolene formation reactions.

  17. Structural and catalytic effects of an invariant purine substitution in the hammerhead ribozyme: implications for the mechanism of acid-base catalysis.

    Science.gov (United States)

    Schultz, Eric P; Vasquez, Ernesto E; Scott, William G

    2014-09-01

    The hammerhead ribozyme catalyzes RNA cleavage via acid-base catalysis. Whether it does so by general acid-base catalysis, in which the RNA itself donates and abstracts protons in the transition state, as is typically assumed, or by specific acid-base catalysis, in which the RNA plays a structural role and proton transfer is mediated by active-site water molecules, is unknown. Previous biochemical and crystallographic experiments implicate an invariant purine in the active site, G12, as the general base. However, G12 may play a structural role consistent with specific base catalysis. To better understand the role of G12 in the mechanism of hammerhead catalysis, a 2.2 Å resolution crystal structure of a hammerhead ribozyme from Schistosoma mansoni with a purine substituted for G12 in the active site of the ribozyme was obtained. Comparison of this structure (PDB entry 3zd4), in which A12 is substituted for G, with three previously determined structures that now serve as important experimental controls, allows the identification of structural perturbations that are owing to the purine substitution itself. Kinetic measurements for G12 purine-substituted schistosomal hammerheads confirm a previously observed dependence of rate on the pK(a) of the substituted purine; in both cases inosine, which is similar to G in pK(a) and hydrogen-bonding properties, is unexpectedly inactive. Structural comparisons indicate that this may primarily be owing to the lack of the exocyclic 2-amino group in the G12A and G12I substitutions and its structural effect upon both the nucleotide base and phosphate of A9. The latter involves the perturbation of a previously identified and well characterized metal ion-binding site known to be catalytically important in both minimal and full-length hammerhead ribozyme sequences. The results permit it to be suggested that G12 plays an important role in stabilizing the active-site structure. This result, although not inconsistent with the potential

  18. Activation of organozinc reagents with t-Bu-P4 base for transition metal-free catalytic SN2' reaction.

    Science.gov (United States)

    Kobayashi, Koji; Ueno, Masahiro; Naka, Hiroshi; Kondo, Yoshinori

    2008-08-28

    The t-Bu-P4 base was found to be an excellent catalyst for activating organozinc reagents and was used to promote the S(N)2' reaction of alpha,beta-unsaturated esters bearing a gamma-chloride using various organozinc reagents: these reactions proceeded in high yields with excellent chemo-and regioselectivity.

  19. Integration of Methane Steam Reforming and Water Gas Shift Reaction in a Pd/Au/Pd-Based Catalytic Membrane Reactor for Process Intensification.

    Science.gov (United States)

    Castro-Dominguez, Bernardo; Mardilovich, Ivan P; Ma, Liang-Chih; Ma, Rui; Dixon, Anthony G; Kazantzis, Nikolaos K; Ma, Yi Hua

    2016-09-19

    Palladium-based catalytic membrane reactors (CMRs) effectively remove H₂ to induce higher conversions in methane steam reforming (MSR) and water-gas-shift reactions (WGS). Within such a context, this work evaluates the technical performance of a novel CMR, which utilizes two catalysts in series, rather than one. In the process system under consideration, the first catalyst, confined within the shell side of the reactor, reforms methane with water yielding H₂, CO and CO₂. After reforming is completed, a second catalyst, positioned in series, reacts with CO and water through the WGS reaction yielding pure H₂O, CO₂ and H₂. A tubular composite asymmetric Pd/Au/Pd membrane is situated throughout the reactor to continuously remove the produced H₂ and induce higher methane and CO conversions while yielding ultrapure H₂ and compressed CO₂ ready for dehydration. Experimental results involving (i) a conventional packed bed reactor packed (PBR) for MSR, (ii) a PBR with five layers of two catalysts in series and (iii) a CMR with two layers of two catalysts in series are comparatively assessed and thoroughly characterized. Furthermore, a comprehensive 2D computational fluid dynamics (CFD) model was developed to explore further the features of the proposed configuration. The reaction was studied at different process intensification-relevant conditions, such as space velocities, temperatures, pressures and initial feed gas composition. Finally, it is demonstrated that the above CMR module, which was operated for 600 h, displays quite high H₂ permeance and purity, high CH₄ conversion levels and reduced CO yields.

  20. Peculiarities of formation of phase composition, porous structure, and catalytic properties of tungsten oxide-based macroporous materials fabricated by sol–gel synthesis

    Energy Technology Data Exchange (ETDEWEB)

    Papynov, Evgeniy Konstantinovich, E-mail: Papynov@mail.ru [Institute of Chemistry, Far East Branch, Russian Academy of Sciences, Prospect 100-let Vladivostoku, 159, Vladivostok 690022 (Russian Federation); Far Eastern Federal University, School of Natural Sciences, Suhanova, 8, Vladivostok 690091 (Russian Federation); Mayorov, Vitaliy Yurevich, E-mail: 024205@inbox.ru [Institute of Chemistry, Far East Branch, Russian Academy of Sciences, Prospect 100-let Vladivostoku, 159, Vladivostok 690022 (Russian Federation); Palamarchuk, Marina Sergeevna, E-mail: 02.06.1984@mail.ru [Institute of Chemistry, Far East Branch, Russian Academy of Sciences, Prospect 100-let Vladivostoku, 159, Vladivostok 690022 (Russian Federation); Avramenko, Valentin Aleksandrovich, E-mail: avramenko1@yandex.ru [Institute of Chemistry, Far East Branch, Russian Academy of Sciences, Prospect 100-let Vladivostoku, 159, Vladivostok 690022 (Russian Federation); Far Eastern Federal University, School of Natural Sciences, Suhanova, 8, Vladivostok 690091 (Russian Federation)

    2014-02-15

    The method of template sol–gel synthesis of tungsten oxide-based macroporous materials using ‘core–shell’ latex particles as colloid templates is described. The chemical composition and structural characteristics of the synthesized macroporous oxide systems have been investigated. The peculiarities of formation of material phase composition and macroporous structure under different template thermal destruction conditions have been revealed. An optimal method of a targeted synthesis of the crystalline tungsten(VI) oxide having a defect-free macroporous structure (average pore size 160 nm) and efficient catalytic properties under organic liquid phase oxidation conditions has been suggested. The prospects of the fabricated material application as catalysts of hydrothermal oxidation of radionuclide organic complexes at radioactive waste decontamination have been demonstrated. - Highlights: • Macroporous tungsten oxides were fabricated via sol–gel process. • The correlation between synthesis conditions and composition was determined. • Influence of synthesis conditions on porous structure has been explained. • The effects of template thermodestruction have been set up. • High potential of such materials for catalysis applications has been shown.

  1. Radiolytic Synthesis of Pt-Ru Catalysts Based on Functional Polymer-Grafted MWNT and Their Catalytic Efficiency for CO and MeOH

    Directory of Open Access Journals (Sweden)

    Dae-Soo Yang

    2011-01-01

    Full Text Available Pt-Ru catalysts based on functional polymer-grafted MWNT (Pt-Ru@FP-MWNT were prepared by radiolytic deposition of Pt-Ru nanoparticles on functional polymer-grafted multiwalled carbon nanotube (FP-MWNT. Three different types of functional polymers, poly(acrylic acid (PAAc, poly(methacrylic acid (PMAc, and poly(vinylphenyl boronic acid (PVPBAc, were grafted on the MWNT surface by radiation-induced graft polymerization (RIGP. Then, Pt-Ru nanoparticles were deposited onto the FP-MWNT supports by the reduction of metal ions using γ-irradiation to obtain Pt-Ru@FP-MWNT catalysts. The Pt-Ru@FP-MWNT catalysts were then characterized by XRD, XPS, TEM ,and elemental analysis. The catalytic efficiency of Pt-Ru@FP-MWNT catalyst was examined for CO stripping and MeOH oxidation for use in a direct methanol fuel cell (DMFC. The Pt-Ru@PVPBAc-MWNT catalyst shows enhanced activity for electro-oxidation of CO and MeOH oxidation over that of the commercial E-TEK catalyst.

  2. Synthesis, characterization, fluorescence and catalytic activity of some new complexes of unsymmetrical Schiff base of 2-pyridinecarboxaldehyde with 2,6-diaminopyridine

    Science.gov (United States)

    Ali, Omyma A. M.; El-Medani, Samir M.; Ahmed, Doaa A.; Nassar, Doaa A.

    2015-06-01

    The Schiff base, 2-[(pyridin-2-ylmethylidene)amino]-6-aminopyridine (L) was synthesized by 1:1 condensation of 2-pyridinecarboxaldehyde and 2,6-diaminopyridine. The ligand and its complexes were characterized by different physicochemical studies. The analytical and spectroscopic tools indicated that the synthesized complexes have the general formulae: [M(L)Cl2]·2H2O (M = Cu(II), Ni(II) and Co(II)), [La(L)3](NO3)3·3H2O and [Sm(L)(ClO4)3]·3H2O. Vibrational spectra indicated the coordination of L to metal ions through its pyridyl and azomethine nitrogen atoms. The presence of water molecules in all reported complexes has been supported by TG/DTA studies. Kinetic and thermodynamic parameters were computed using Coats and Redfern method. The prepared ligand and its complexes exhibited intraligand (π-π∗) fluorescence and can potentially serve as photoactive materials. The catalytic activity of the complexes toward the decomposition of hydrogen peroxide was investigated. Both the ligand and its complexes have been screened for antibacterial activities.

  3. Selection of Chelated Fe (III)/Fe (II) Catalytic Oxidation Agents for Desulfurization Based on Iron Complexation Method

    Institute of Scientific and Technical Information of China (English)

    Luo Ying; Liu Youzhi; Qi Guisheng; Guo Huidong; Zhu Zhengfeng

    2014-01-01

    Optimization of factors inlfuencing the experiments on reactions involving 8 different chelating agents and sol-uble Fe (III)/Fe (II) salts was carried out to yield chelated iron complexes. A combination of optimized inlfuencing factors has resulted in a Fe chelating capacity of the iron-based desulfurization solution to be equal to 6.83-13.56 g/L at a redox potential of 0.185-0.3. The desulfurization performance of Fe (III)/Fe (II) chelating agents was investigated on a simulated sulfur-containing industrial gas composed of H2S and N2 in a cross-lfow rotating packed bed. Test results have revealed that the proposed iron-based desulfurization solution showed a sulfur removal efifciency of over 99%along with a Fe chelating capacity exceeding 1.35 g/L. This desulfurization technology which has practical application prospect is currently in the phase of commercial scale-up study.

  4. Catalytic Enantioselective Aryl Transfer to Aldehydes Using Chiral 2,2’-Bispyrrolidine-Based Salan Ligands

    Directory of Open Access Journals (Sweden)

    Yixiang Cheng

    2011-04-01

    Full Text Available Chiral C2-symmetric diamines have emerged as versatile auxiliaries or ligands in numerous asymmetric transformations. Chiral 2,2’-bispyrrolidine-based salan ligands were prepared and applied to the asymmetric aryl transfer to aldehydes with arylboronic acids as the source of transferable aryl groups. The corresponding diarylmethanols were obtained in high yields with moderate to good enantioselectivitives of up to 83% ee.

  5. Mesoporous Silica Based Gold Catalysts: Novel Synthesis and Application in Catalytic Oxidation of CO and Volatile Organic Compounds (VOCs

    Directory of Open Access Journals (Sweden)

    Leonarda F. Liotta

    2013-10-01

    Full Text Available Gold nanoparticles, particularly with the particle size of 2–5 nm, have attracted increasing research attention during the past decades due to their surprisingly high activity in CO and volatile organic compounds (VOCs oxidation at low temperatures. In particular, CO oxidation below room temperature has been extensively studied on gold nanoparticles supported on several oxides (TiO2, Fe2O3, CeO2, etc.. Recently, mesoporous silica materials (such as SBA-15, MCM-41, MCM-48 and HMS possessing ordered channel structures and suitable pore diameters, large internal surface areas, thermal stabilities and excellent mechanical properties, have been investigated as suitable hosts for gold nanoparticles. In this review we highlight the development of novel mesoporous silica based gold catalysts based on examples, mostly from recently reported results. Several synthesis methods are described herein. In detail we report: the modification of silica with organic functional groups; the one-pot synthesis with the incorporation of both gold and coupling agent containing functionality for the synthesis of mesoporous silica; the use of cationic gold complexes; the synthesis of silica in the presence of gold colloids or the dispersion of gold colloids protected by ligands or polymers onto silica; the modification of silica by other metal oxides; other conventional preparation methods to form mesoporous silica based gold catalysts. The gold based catalysts prepared as such demonstrate good potential for use in oxidation of CO and VOCs at low temperatures. From the wide family of VOCs, the oxidation of methanol and dimethyldisulfide has been addressed in the present review.

  6. Synthesis of Titanium (Ⅳ) Complexes with Schiff-base Ligand and Their Catalytic Activities for Polymerization of Ethylene and Styrene

    Institute of Scientific and Technical Information of China (English)

    YONG, Li; HUANG, Ji-Ling; LIAN, Bing; QIAN Yan-Long

    2001-01-01

    Peaction of titanium(Ⅳ) isopropoxide with the unusual kind of Shiff-base in 1:1 molar ratio gives a variety of new derivatives of titanium (Ⅳ) in high yield. These complexes were characterized by elemental analyses, IR, MS and 1H NMR.It was noteworthy to find that all these complexes were active for polymerizations of ethylene and styrene when activated by a Lewis acid cocatalyst (MAO).

  7. Catalytic depolymerisation of starch-based industrial waste:use of non-conventional activation methods and novel reaction media

    OpenAIRE

    Hernoux-Villière, A. (Audrey)

    2013-01-01

    Abstract The rapid increase of energy demand for transportation generates a rise of environmental pollution, stimulating the development of alternative sources of energy. Biomass is considered as the main organic carbon source of energy to substitute petroleum permitting sustainable production of chemicals and transportation fuels. Biowastes, residues and non-edible feedstock possess high potential resources avoiding food competition. This research aims to convert starch-based industria...

  8. Catalytic activity of acid and base with different concentration on sol-gel kinetics of silica by ultrasonic method.

    Science.gov (United States)

    Das, R K; Das, M

    2015-09-01

    The effects of both acid (acetic acid) and base (ammonia) catalysts in varying on the sol-gel synthesis of SiO2 nanoparticles using tetra ethyl ortho silicate (TEOS) as a precursor was determined by ultrasonic method. The ultrasonic velocity was received by pulsar receiver. The ultrasonic velocity in the sol and the parameter ΔT (time difference between the original pulse and first back wall echo of the sol) was varied with time of gelation. The graphs of ln[ln1/ΔT] vs ln(t), indicate two region - nonlinear region and a linear region. The time corresponds to the point at which the non-linear region change to linear region is considered as gel time for the respective solutions. Gelation time is found to be dependent on the concentration and types of catalyst and is found from the graphs based on Avrami equation. The rate of condensation is found to be faster for base catalyst. The gelation process was also characterized by viscosity measurement. Normal sol-gel process was also carried out along with the ultrasonic one to compare the effectiveness of ultrasonic. The silica gel was calcined and the powdered sample was characterized with scanning electron microscopy, energy dispersive spectra, X-ray diffractogram, and FTIR spectroscopy.

  9. Catalytic hydrotreating process

    Science.gov (United States)

    Karr, Jr., Clarence; McCaskill, Kenneth B.

    1978-01-01

    Carbonaceous liquids boiling above about 300.degree. C such as tars, petroleum residuals, shale oils and coal-derived liquids are catalytically hydrotreated by introducing the carbonaceous liquid into a reaction zone at a temperature in the range of 300.degree. to 450.degree. C and a pressure in the range of 300 to 4000 psig for effecting contact between the carbonaceous liquid and a catalytic transition metal sulfide in the reaction zone as a layer on a hydrogen permeable transition metal substrate and then introducing hydrogen into the reaction zone by diffusing the hydrogen through the substrate to effect the hydrogenation of the carbonaceous liquid in the presence of the catalytic sulfide layer.

  10. An automated flow for directed evolution based on detection of promiscuous scaffolds using spatial and electrostatic properties of catalytic residues.

    Directory of Open Access Journals (Sweden)

    Sandeep Chakraborty

    Full Text Available The aspiration to mimic and accelerate natural evolution has fueled interest in directed evolution experiments, which endow or enhance functionality in enzymes. Barring a few de novo approaches, most methods take a template protein having the desired activity, known active site residues and structure, and proceed to select a target protein which has a pre-existing scaffold congruent to the template motif. Previously, we have established a computational method (CLASP based on spatial and electrostatic properties to detect active sites, and a method to quantify promiscuity in proteins. We exploit the prospect of promiscuous active sites to serve as the starting point for directed evolution and present a method to select a target protein which possesses a significant partial match with the template scaffold (DECAAF. A library of partial motifs, constructed from the active site residues of the template protein, is used to rank a set of target proteins based on maximal significant matches with the partial motifs, and cull out the best candidate from the reduced set as the target protein. Considering the scenario where this 'incubator' protein lacks activity, we identify mutations in the target protein that will mirror the template motif by superimposing the target and template protein based on the partial match. Using this superimposition technique, we analyzed the less than expected gain of activity achieved by an attempt to induce β-lactamase activity in a penicillin binding protein (PBP (PBP-A from T. elongatus, and attributed this to steric hindrance from neighboring residues. We also propose mutations in PBP-5 from E. coli, which does not have similar steric constraints. The flow details have been worked out in an example which aims to select a substitute protein for human neutrophil elastase, preferably related to grapevines, in a chimeric anti-microbial enzyme which bolsters the innate immune defense system of grapevines.

  11. Facile synthesis of free-standing Pd-based nanomembranes with enhanced catalytic performance for methanol/ethanol oxidation

    Energy Technology Data Exchange (ETDEWEB)

    Wu, Haoxi [State Key Laboratory of Electroanalytical Chemistry, Changchun Institute of Applied Chemistry, Chinese Academy of Sciences, Changchun 130022, Jilin (China); Graduate University of the Chinese Academy of Sciences, Beijing 100039 (China); Li, Haijuan; Zhai, Yujuan; Xu, Xiaolong; Jin, Yongdong [State Key Laboratory of Electroanalytical Chemistry, Changchun Institute of Applied Chemistry, Chinese Academy of Sciences, Changchun 130022, Jilin (China)

    2012-03-22

    Macroscopic free-standing Pd and Pd/Pt bimetallic monolayer nanomembranes (Pd- and Pd/Pt-FNMs) derived from the spontaneous self-assembly of the as-produced Pd NPs and Pd/Pt bimetallic NPs at the water-air interface within 15 min are fabricated, respectively. The one-step method allows the growth of high-quality Pd-based FNMs with well-defined monolayer morphology, which exhibit significantly higher electrocatalytic activity for methanol/ethanol oxidation than commercial catalysts. (Copyright copyright 2012 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  12. Selection of Chelated Fe (III)/Fe (II) Catalytic Oxidation Agents for Desulfurization Based on Iron Complexation Method

    Institute of Scientific and Technical Information of China (English)

    Luo Ying; Liu Youzhi; Qi Guisheng; Guo Huidong; Zhu Zhengfeng

    2014-01-01

    Optimization of factors inlfuencing the experiments on reactions involving 8 different chelating agents and sol-uble Fe (III)/Fe (II) salts was carried out to yield chelated iron complexes. A combination of optimized inlfuencing factors has resulted in a Fe chelating capacity of the iron-based desulfurization solution to be equal to 6.83—13.56 g/L at a redox potential of 0.185—0.3. The desulfurization performance of Fe (III)/Fe (II) chelating agents was investigated on a simulated sulfur-containing industrial gas composed of H2S and N2 in a cross-lfow rotating packed bed. Test results have revealed that the proposed iron-based desulfurization solution showed a sulfur removal efifciency of over 99%along with a Fe chelating capacity exceeding 1.35 g/L. This desulfurization technology which has practical application prospect is currently in the phase of commercial scale-up study.

  13. Catalytically Enhanced Hydrogen Sorption in Mg-MgH2 by Coupling Vanadium-Based Catalyst and Carbon Nanotubes

    Directory of Open Access Journals (Sweden)

    Atikah Kadri

    2015-06-01

    Full Text Available Mg (MgH2-based composites, using carbon nanotubes (CNTs and pre-synthesized vanadium-based complex (VCat as the catalysts, were prepared by high-energy ball milling technique. The synergistic effect of coupling CNTs and VCat in MgH2 was observed for an ultra-fast absorption rate of 6.50 wt. % of hydrogen per minute and 6.50 wt. % of hydrogen release in 10 min at 200 °C and 300 °C, respectively. The temperature programmed desorption (TPD results reveal that coupling VCat and CNTs reduces both peak and onset temperatures by more than 60 °C and 114 °C, respectively. In addition, the presence of both VCat and CNTs reduces the enthalpy and entropy of desorption of about 7 kJ/mol H2 and 11 J/mol H2·K, respectively, as compared to those of the commercial MgH2, which ascribe to the decrease of desorption temperature. From the study of the effect of CNTs milling time, it is shown that partially destroyed CNTs (shorter milling time are better to enhance the hydrogen sorption performance.

  14. SYNTHESIS AND CATALYTIC PROPERTY OF POLYSTYRENE SUPPORTED PHENYLALANINE SCHIFF BASE COMPLEX OF Mn(Ⅱ) IN AEROBIC OXIDATION OF CYCLOHEXENE

    Institute of Scientific and Technical Information of China (English)

    ZHAO Ganqing; XIE Jimin; LU Xiaoqing; SUN Lu

    2006-01-01

    The polystyrene supported phenylalanine Schiff base complex of Mn(Ⅱ)(PS-Sal-Phe-Mn)was prepared with chloromethylated styrene polymer beads, 2,4-dihydroxybenzaldehyde,L-phenylalanine and manganese(Ⅱ)acetate tetrahyrate., The polymeric ligand and the complex were characterized by FT-IR,, small area X-ray photoelectron spectroscopy(XPS), and ICP-AES. In the presence of the manganese complex, cyclohexene(1)was effectively oxidized by molecular oxygen without reductant. The major products of the reaction were 2-cyclohexen-1-ol(2),2-cyclohexen-1-one(3)and 2-cyclohexen-1- hydroperoxide(4), which was different with typical oxidation of cyclohexene. The influence of reaction temperature and additive for oxidation had been studied. The selectivity of 2-cyclohexen-l-hydroperoxide varied with reaction time and different additives. The mechanism of cyclohexene oxidation had also been discussed.

  15. Catalytic Enantioselective Olefin Metathesis in Natural Product Synthesis. Chiral Metal-Based Complexes that Deliver High Enantioselectivity and More

    Science.gov (United States)

    Malcolmson, Steven J.; Meek, Simon J.; Zhugralin, Adil R.

    2012-01-01

    Chiral olefin metathesis catalysts enable chemists to access enantiomerically enriched small molecules with high efficiency; synthesis schemes involving such complexes can be substantially more concise than those that would involve enantiomerically pure substrates and achiral Mo alkylidenes or Ru-based carbenes. The scope of research towards design and development of chiral catalysts is not limited to discovery of complexes that are merely the chiral versions of the related achiral variants. A chiral olefin metathesis catalyst, in addition to furnishing products of high enantiomeric purity, can offer levels of efficiency, product selectivity and/or olefin stereoselectivity that are unavailable through the achiral variants. Such positive attributes of chiral catalysts (whether utilized in racemic or enantiomerically enriched form) should be considered as general, applicable to other classes of transformations. PMID:19967680

  16. Magnetic, high-field EPR studies and catalytic activity of Schiff base tetranuclear CuII2FeIII2 complexes obtained by direct synthesis.

    Science.gov (United States)

    Nesterova, Oksana V; Chygorin, Eduard N; Kokozay, Vladimir N; Bon, Volodymyr V; Omelchenko, Irina V; Shishkin, Oleg V; Titiš, Ján; Boča, Roman; Pombeiro, Armando J L; Ozarowski, Andrew

    2013-12-28

    Two novel heterometallic complexes [Cu2Fe2(HL(1))2(H2L(1))2]·10DMSO (1) and [Cu2Fe2(HL(2))2(H2L(2))2]·2DMF (2) have been prepared using the open-air reaction of copper powder, iron(II) chloride and DMSO (1) or DMF (2) solutions of the polydentate Schiff base (H4L(1), 1; H4L(2), 2) formed in situ from salicylaldehyde (1) or 5-bromo-salicylaldehyde (2) and tris(hydroxymethyl)aminomethane. Crystallographic analysis revealed that both compounds are based on the centrosymmetric tetranuclear core {Cu(II)2Fe(III)2(μ-O)6} where metal centres are joined by μ-O bridges from the deprotonated ligands forming a nonlinear chain-like arrangement. Variable-temperature (1.8-300 K) magnetic susceptibility measurements of 1 and 2 showed a decrease of the effective magnetic moment value at low temperature, indicative of antiferromagnetic coupling (JCu-Fe/hc = -10.2 cm(-1), JFe-Fe/hc = -10.5 cm(-1) in 1, JCu-Fe/hc = -10.5 cm(-1), JFe-Fe/hc = -8.93 cm(-1) in 2) between the magnetic centres in both compounds. They reveal an exceptionally high catalytic activity in the oxidation of cyclohexane with hydrogen peroxide under mild conditions, with the best observed yield/TON combined values of 36%/596 and 44%/1.1 × 10(3) for 1 and 2, respectively.

  17. Synthesis, characterization and catalytic applications of triden tate Schiff base derivatives of bis and mono(cyclopentadienyl) lanthanocene complexes

    Institute of Scientific and Technical Information of China (English)

    YOUSAF, Muhammad; QIAN, Yan-Long

    2000-01-01

    Seven kinds of lanthanocene complexes were prepared by the reaction of tridentate Schiff base { N-(2-methoxyphenyi)sali cylideneamine} with tris(cyclopentadienyl)lanthanide tetrahy drofuranate or bis (cyclopentadienyl) lanthanide chloride te trahydrofuranate in THF. All the complexes were character ized by MS, EA and IR respeectively. The structure of {Cp2LnC14H13NO2) Ln=Sm, Dy, Y, Er} (1-4) was fur ther confirmed by X-ray determination of Cp2Sm(C14H13NO2) (1) which indicates that the complex is monomeric in which central metal is coordinatively saturated by two cyclopentadi enyl rings, two oxygens and one nitrogen of the ligand. The i somerization of 1,5-hexadiene explains that complexes (1-4) isomerize this monomer into a -mixture of 1,4-hexadiene, 2,4- hexadiene, 1,3-hexadiene,methylenecyclopentane and methyl cyclopentene. Similarly complexes{CpLn(Cl)C14H13NO2) (THF) (Ln= Sm, Dy, Y, Er)} (5-7) polymerize methyi methacrylate (MMA) to give polyMMA (PMMA) in 51.8% yield and high molecular weight (274 × 103), which shows narrow molecular weight distributions and partially syndiotac tic.

  18. SOFC system with integrated catalytic fuel processing

    Science.gov (United States)

    Finnerty, Caine; Tompsett, Geoff. A.; Kendall, Kevin; Ormerod, R. Mark

    In recent years, there has been much interest in the development of solid oxide fuel cell technology operating directly on hydrocarbon fuels. The development of a catalytic fuel processing system, which is integrated with the solid oxide fuel cell (SOFC) power source is outlined here. The catalytic device utilises a novel three-way catalytic system consisting of an in situ pre-reformer catalyst, the fuel cell anode catalyst and a platinum-based combustion catalyst. The three individual catalytic stages have been tested in a model catalytic microreactor. Both temperature-programmed and isothermal reaction techniques have been applied. Results from these experiments were used to design the demonstration SOFC unit. The apparatus used for catalytic characterisation can also perform in situ electrochemical measurements as described in previous papers [C.M. Finnerty, R.H. Cunningham, K. Kendall, R.M. Ormerod, Chem. Commun. (1998) 915-916; C.M. Finnerty, N.J. Coe, R.H. Cunningham, R.M. Ormerod, Catal. Today 46 (1998) 137-145]. This enabled the performance of the SOFC to be determined at a range of temperatures and reaction conditions, with current output of 290 mA cm -2 at 0.5 V, being recorded. Methane and butane have been evaluated as fuels. Thus, optimisation of the in situ partial oxidation pre-reforming catalyst was essential, with catalysts producing high H 2/CO ratios at reaction temperatures between 873 K and 1173 K being chosen. These included Ru and Ni/Mo-based catalysts. Hydrocarbon fuels were directly injected into the catalytic SOFC system. Microreactor measurements revealed the reaction mechanisms as the fuel was transported through the three-catalyst device. The demonstration system showed that the fuel processing could be successfully integrated with the SOFC stack.

  19. SOFC system with integrated catalytic fuel processing

    Energy Technology Data Exchange (ETDEWEB)

    Finnerty, C.; Tompsett, G.A.; Kendall, K.; Ormerod, R.M. [Birchall Centre for Inorganic Chemistry and Materials Science, Keele Univ. (United Kingdom)

    2000-03-01

    In recent years, there has been much interest in the development of solid oxide fuel cell technology operating directly on hydrocarbon fuels. The development of a catalytic fuel processing system, which is integrated with the solid oxide fuel cell (SOFC) power source is outlined here. The catalytic device utilises a novel three-way catalytic system consisting of an in situ pre-reformer catalyst, the fuel cell anode catalyst and a platinum-based combustion catalyst. The three individual catalytic stages have been tested in a model catalytic microreactor. Both temperature-programmed and isothermal reaction techniques have been applied. Results from these experiments were used to design the demonstration SOFC unit. The apparatus used for catalytic characterisation can also perform in situ electrochemical measurements as described in previous papers [C.M. Finnerty, R.H. Cunningham, K. Kendall, R.M. Ormerod, Chem. Commun. (1998) 915-916; C.M. Finnerty, N.J. Coe, R.H. Cunningham, R.M. Ormerod, Catal. Today 46 (1998) 137-145]. This enabled the performance of the SOFC to be determined at a range of temperatures and reaction conditions, with current output of 290 mA cm{sup -2} at 0.5 V, being recorded. Methane and butane have been evaluated as fuels. Thus, optimisation of the in situ partial oxidation pre-reforming catalyst was essential, with catalysts producing high H{sub 2}/CO ratios at reaction temperatures between 873 K and 1173 K being chosen. These included Ru and Ni/Mo-based catalysts. Hydrocarbon fuels were directly injected into the catalytic SOFC system. Microreactor measurements revealed the reaction mechanisms as the fuel was transported through the three-catalyst device. The demonstration system showed that the fuel processing could be successfully integrated with the SOFC stack. (orig.)

  20. Syntheses, structures, molecular and cationic recognitions and catalytic properties of two lanthanide coordination polymers based on a flexible tricarboxylate

    Energy Technology Data Exchange (ETDEWEB)

    Zhu, Yu; Wang, Yan-Mei; Xu, Ji; Liu, Pan; Weththasinha, H.A.B.M.D.; Wu, Yun-Long; Lu, Xiao-Qing; Xie, Ji-Min, E-mail: xiejm391@sohu.com

    2014-11-15

    Two lanthanide coordination polymers, namely, ([La(TTTA)(H{sub 2}O){sub 2}]·2H{sub 2}O){sub n} (La-TTTA) and [Nd(TTTA)(H{sub 2}O){sub 2}]·2H{sub 2}O){sub n} (Nd-TTTA) have been hydrothermally synthesized through the reaction of lanthanide ions (La{sup 3+} and Nd{sup 3+}) with the flexible tripodal ligand 2,2′,2″-[1,3,5-triazine-2,4,6-triyltris(thio)]tris-acetic acid (H{sub 3}TTTA). La-TTTA and Nd-TTTA are isostructural and both show three dimensional structures. La-TTTA and Nd-TTTA show good recognition of amine molecules via quenching the luminescent intensities in amines emulsions. They can also recognize Fe{sup 3+}, Cu{sup 2+}, Mg{sup 2+}, Cr{sup 3+} and Co{sup 2+} ions with the quenching the peak around 361 nm when the compounds immersed in ionic solutions. The two compounds act as efficient Lewis acid catalysts for the cyanosilylation of benzaldehyde and derivatives in high yields shortly due to the strong Lewis acidity and the possible open sites of the lanthanide ions. - Graphical abstract: We have synthesized two isostructural 3D compounds based on H{sub 3}TTTA. They are chemical sensor of amine solvents and cations. They have higher yields and TOFs to catalyze cyanosilylation reactions. - Highlights: • The compounds show recognition of amine molecules via quenching luminescent intensities. • The compounds recognize Fe{sup 3+}, Cu{sup 2+}, Mg{sup 2+}, Cr{sup 3+} and Co{sup 2+} ions via quenching the peak around 361 nm. • They act as efficient Lewis acid catalysts for the cyanosilylation reactions in high yields.

  1. Comparison between a Water-Based and a Solvent-Based Impregnation Method towards Dispersed CuO/SBA-15 Catalysts: Texture, Structure and Catalytic Performance in Automotive Exhaust Gas Abatement

    Directory of Open Access Journals (Sweden)

    Qi Xin

    2016-10-01

    Full Text Available Supported copper oxide nanoparticles are a potential candidate for replacing the rare and expensive precious metals within the automotive three-way catalyst. However, a well-designed dispersion method is necessary to allow a stable high loading of active material, compensating its lower intrinsic activity and stability. In this work, a CuO-loaded SBA-15 catalyst has been manufactured by two methods. The ammonia-driven deposition precipitation (ADP and the molecular designed dispersion (MDD methods are both considered as efficient deposition methods to provide well-dispersed copper oxide-based catalysts. Their morphology, copper dispersion and the chemical state of copper were characterized and compared. Due to the differences in the synthesis approach, a difference in the obtained copper oxide phases has been observed, leading to a distinct behavior in the catalytic performance. The structure-activity correlation of both catalysts has also been revealed for automotive exhaust gas abatement. Results demonstrate that various copper species can be formed depending on the precursor–support interaction, affecting selectivity and conversion during the catalytic reaction.

  2. Catalytic efficiency of designed catalytic proteins.

    Science.gov (United States)

    Korendovych, Ivan V; DeGrado, William F

    2014-08-01

    The de novo design of catalysts that mimic the affinity and specificity of natural enzymes remains one of the Holy Grails of chemistry. Despite decades of concerted effort we are still unable to design catalysts as efficient as enzymes. Here we critically evaluate approaches to (re)design of novel catalytic function in proteins using two test cases: Kemp elimination and ester hydrolysis. We show that the degree of success thus far has been modest when the rate enhancements seen for the designed proteins are compared with the rate enhancements by small molecule catalysts in solvents with properties similar to the active site. Nevertheless, there are reasons for optimism: the design methods are ever improving and the resulting catalyst can be efficiently improved using directed evolution.

  3. Catalytic Phosphination and Arsination

    Institute of Scientific and Technical Information of China (English)

    Kwong Fuk Yee; Chan Kin Shing

    2004-01-01

    The catalytic, user-friendly phosphination and arsination of aryl halides and triflates by triphenylphosphine and triphenylarsine using palladium catalysts have provided a facile synthesis of functionalized aryl phosphines and arsines in neutral media. Modification of the cynaoarisne yielded optically active N, As ligands which will be screened in various asymmetric catalysis.

  4. Mitsunobu Reactions Catalytic in Phosphine and a Fully Catalytic System.

    Science.gov (United States)

    Buonomo, Joseph A; Aldrich, Courtney C

    2015-10-26

    The Mitsunobu reaction is renowned for its mild reaction conditions and broad substrate tolerance, but has limited utility in process chemistry and industrial applications due to poor atom economy and the generation of stoichiometric phosphine oxide and hydrazine by-products that complicate purification. A catalytic Mitsunobu reaction using innocuous reagents to recycle these by-products would overcome both of these shortcomings. Herein we report a protocol that is catalytic in phosphine (1-phenylphospholane) employing phenylsilane to recycle the catalyst. Integration of this phosphine catalytic cycle with Taniguchi's azocarboxylate catalytic system provided the first fully catalytic Mitsunobu reaction.

  5. Synthesis, Characterization, and Catalytic Activity of Sulfonated Carbon-Based Catalysts Derived From Rubber Tree Leaves and Pulp and Paper Mill Waste

    Science.gov (United States)

    Janaun, J.; Sinin, E.; Hiew, S. F.; Kong, A. M. T.; Lahin, F. A.

    2016-06-01

    Sulfonated carbon-based catalysts derived from rubber tree leaves, and pulp and paper mill waste were synthesized and characterized. Three types of catalyst synthesized were sulfonated rubber tree leaves (S-RTL), pyrolysed sludge char (P-SC) and sulfonated sludge char (S-SC). Sulfonated rubber tree leaves (S-RTL) and sulfonated sludge char (S-SC) were prepared through pyrolysis followed by functionalization via sulfonation process whereas, P- SC was only pyrolyzed without sulfonation. The characterization results indicated sulfonic acids, hydroxyl, and carboxyl moieties were detected in S-RTL and S-SC, but no sulfonic acid was detected in P-SC. Total acidity test showed S-RTL had the highest value followed by S-SC and P-SC. The thermal stability of S-RTL and S-SC were up to 230oC as the loss was associated with the decomposition of sulfonic acid group, whereas, P-SC showed higher stability than the S-RTL and S-SC. Morphology analysis showed that S-RTL consisted of an amorphous carbon structure, and a crystalline structure for P-SC and S-SC. Furthermore, traces of metal components were also detected on all of the catalysts. The catalyst catalytic activity was tested through esterification of oleic acid with methanol. The results showed that the reaction using S-RTL catalyst produced the highest conversion (99.9%) followed by P-SC (88.4%) and lastly S-SC (82.7%). The synthesized catalysts showed high potential to be used in biodiesel production.

  6. EPR Spectroscopy of catalytic systems based on nickel complexes of 1,4-diaza-1,3-butadiene (α-diimine) ligands in hydrogenation and polymerization reactions

    Science.gov (United States)

    Titova, Yu. Yu.; Belykh, L. B.; Schmidt, F. K.

    2015-01-01

    EPR spectroscopy is used to study catalytic hydration and polymerization reaction systems based on α-diimine complexes of Ni(0) and Ni(II) with the general formula NiBr2(DAD-R) (R = -C3H7 or -CH3) or 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)), in combination with Lewis acids (AlEt3, AlEt2Cl, AlEtCl2, B(F5C6)3, BF3.OEt2). Ni(I) complexes of the form (DAD-R)NiX2AlX'y(C2H5)3-y composition (an aluminum atom can be replaced by a boron atom) were identified, where R = -CH3 or -C3H7, X = Br, and X' = Cl or -C2H5 and α-diimine anion radicals are included in derivatives of aluminum or boron. Oxidation reactions of the Ni(DAD-CH3)2 complex with aluminum alkyl halides and boron derivatives with formation of paramagnetic nickel complexes are observed. It is found that there is no direct relationship between the polymerization activity of ethylene or hydration of the alkenes and the concentration of paramagnetic particles.

  7. Integration of Methane Steam Reforming and Water Gas Shift Reaction in a Pd/Au/Pd-Based Catalytic Membrane Reactor for Process Intensification

    Science.gov (United States)

    Castro-Dominguez, Bernardo; Mardilovich, Ivan P.; Ma, Liang-Chih; Ma, Rui; Dixon, Anthony G.; Kazantzis, Nikolaos K.; Ma, Yi Hua

    2016-01-01

    Palladium-based catalytic membrane reactors (CMRs) effectively remove H2 to induce higher conversions in methane steam reforming (MSR) and water-gas-shift reactions (WGS). Within such a context, this work evaluates the technical performance of a novel CMR, which utilizes two catalysts in series, rather than one. In the process system under consideration, the first catalyst, confined within the shell side of the reactor, reforms methane with water yielding H2, CO and CO2. After reforming is completed, a second catalyst, positioned in series, reacts with CO and water through the WGS reaction yielding pure H2O, CO2 and H2. A tubular composite asymmetric Pd/Au/Pd membrane is situated throughout the reactor to continuously remove the produced H2 and induce higher methane and CO conversions while yielding ultrapure H2 and compressed CO2 ready for dehydration. Experimental results involving (i) a conventional packed bed reactor packed (PBR) for MSR, (ii) a PBR with five layers of two catalysts in series and (iii) a CMR with two layers of two catalysts in series are comparatively assessed and thoroughly characterized. Furthermore, a comprehensive 2D computational fluid dynamics (CFD) model was developed to explore further the features of the proposed configuration. The reaction was studied at different process intensification-relevant conditions, such as space velocities, temperatures, pressures and initial feed gas composition. Finally, it is demonstrated that the above CMR module, which was operated for 600 h, displays quite high H2 permeance and purity, high CH4 conversion levels and reduced CO yields. PMID:27657143

  8. Integration of Methane Steam Reforming and Water Gas Shift Reaction in a Pd/Au/Pd-Based Catalytic Membrane Reactor for Process Intensification

    Directory of Open Access Journals (Sweden)

    Bernardo Castro-Dominguez

    2016-09-01

    Full Text Available Palladium-based catalytic membrane reactors (CMRs effectively remove H2 to induce higher conversions in methane steam reforming (MSR and water-gas-shift reactions (WGS. Within such a context, this work evaluates the technical performance of a novel CMR, which utilizes two catalysts in series, rather than one. In the process system under consideration, the first catalyst, confined within the shell side of the reactor, reforms methane with water yielding H2, CO and CO2. After reforming is completed, a second catalyst, positioned in series, reacts with CO and water through the WGS reaction yielding pure H2O, CO2 and H2. A tubular composite asymmetric Pd/Au/Pd membrane is situated throughout the reactor to continuously remove the produced H2 and induce higher methane and CO conversions while yielding ultrapure H2 and compressed CO2 ready for dehydration. Experimental results involving (i a conventional packed bed reactor packed (PBR for MSR, (ii a PBR with five layers of two catalysts in series and (iii a CMR with two layers of two catalysts in series are comparatively assessed and thoroughly characterized. Furthermore, a comprehensive 2D computational fluid dynamics (CFD model was developed to explore further the features of the proposed configuration. The reaction was studied at different process intensification-relevant conditions, such as space velocities, temperatures, pressures and initial feed gas composition. Finally, it is demonstrated that the above CMR module, which was operated for 600 h, displays quite high H2 permeance and purity, high CH4 conversion levels and reduced CO yields.

  9. An oxyferrous heme/protein-based radical intermediate is catalytically competent in the catalase reaction of Mycobacterium tuberculosis catalase-peroxidase (KatG).

    Science.gov (United States)

    Suarez, Javier; Ranguelova, Kalina; Jarzecki, Andrzej A; Manzerova, Julia; Krymov, Vladimir; Zhao, Xiangbo; Yu, Shengwei; Metlitsky, Leonid; Gerfen, Gary J; Magliozzo, Richard S

    2009-03-13

    A mechanism accounting for the robust catalase activity in catalase-peroxidases (KatG) presents a new challenge in heme protein enzymology. In Mycobacterium tuberculosis, KatG is the sole catalase and is also responsible for peroxidative activation of isoniazid, an anti-tuberculosis pro-drug. Here, optical stopped-flow spectrophotometry, rapid freeze-quench EPR spectroscopy both at the X-band and at the D-band, and mutagenesis are used to identify catalase reaction intermediates in M. tuberculosis KatG. In the presence of millimolar H2O2 at neutral pH, oxyferrous heme is formed within milliseconds from ferric (resting) KatG, whereas at pH 8.5, low spin ferric heme is formed. Using rapid freeze-quench EPR at X-band under both of these conditions, a narrow doublet radical signal with an 11 G principal hyperfine splitting was detected within the first milliseconds of turnover. The radical and the unique heme intermediates persist in wild-type KatG only during the time course of turnover of excess H2O2 (1000-fold or more). Mutation of Met255, Tyr229, or Trp107, which have covalently linked side chains in a unique distal side adduct (MYW) in wild-type KatG, abolishes this radical and the catalase activity. The D-band EPR spectrum of the radical exhibits a rhombic g tensor with dual gx values (2.00550 and 2.00606) and unique gy (2.00344) and gz values (2.00186) similar to but not typical of native tyrosyl radicals. Density functional theory calculations based on a model of an MYW adduct radical built from x-ray coordinates predict experimentally observed hyperfine interactions and a shift in g values away from the native tyrosyl radical. A catalytic role for an MYW adduct radical in the catalase mechanism of KatG is proposed.

  10. Catalytic CO2 activation assisted by rhenium hydride/B(C6F5)3 frustrated Lewis pairs--metal hydrides functioning as FLP bases.

    Science.gov (United States)

    Jiang, Yanfeng; Blacque, Olivier; Fox, Thomas; Berke, Heinz

    2013-05-22

    Reaction of 1 with B(C6F5)3 under 1 bar of CO2 led to the instantaneous formation of the frustrated Lewis pair (FLP)-type species [ReHBr(NO)(PR3)2(η(2)-O═C═O-B(C6F5)3)] (2, R = iPr a, Cy b) possessing two cis-phosphines and O(CO2)-coordinated B(C6F5)3 groups as verified by NMR spectroscopy and supported by DFT calculations. The attachment of B(C6F5)3 in 2a,b establishes cooperative CO2 activation via the Re-H/B(C6F5)3 Lewis pair, with the Re-H bond playing the role of a Lewis base. The Re(I) η(1)-formato dimer [{Re(μ-Br)(NO)(η(1)-OCH═O-B(C6F5)3)(PiPr3)2}2] (3a) was generated from 2a and represents the first example of a stable rhenium complex bearing two cis-aligned, sterically bulky PiPr3 ligands. Reaction of 3a with H2 cleaved the μ-Br bridges, producing the stable and fully characterized formato dihydrogen complex [ReBrH2(NO)(η(1)-OCH═O-B(C6F5)3)(PiPr3)2] (4a) bearing trans-phosphines. Stoichiometric CO2 reduction of 4a with Et3SiH led to heterolytic splitting of H2 along with formation of bis(triethylsilyl)acetal ((Et3SiO)2CH2, 7). Catalytic reduction of CO2 with Et3SiH was also accomplished with the catalysts 1a,b/B(C6F5)3, 3a, and 4a, showing turnover frequencies (TOFs) between 4 and 9 h(-1). The stoichiometric reaction of 4a with the sterically hindered base 2,2,6,6-tetramethylpiperidine (TMP) furnished H2 ligand deprotonation. Hydrogenations of CO2 using 1a,b/B(C6F5)3, 3a, and 4a as catalysts gave in the presence of TMP TOFs of up to 7.5 h(-1), producing [TMPH][formate] (11). The influence of various bases (R2NH, R = iPr, Cy, SiMe3, 2,4,6-tri-tert-butylpyridine, NEt3, PtBu3) was studied in greater detail, pointing to two crucial factors of the CO2 hydrogenations: the steric bulk and the basicity of the base.

  11. Nickel-based xerogel catalysts: Synthesis via fast sol-gel method and application in catalytic hydrogenation of p-nitrophenol to p-aminophenol

    Energy Technology Data Exchange (ETDEWEB)

    Feng, Jin; Wang, Qiang; Fan, Dongliang; Ma, Lirong; Jiang, Deli; Xie, Jimin, E-mail: xiejm391@sohu.com; Zhu, Jianjun, E-mail: zhjj029@sina.com

    2016-09-30

    out to investigate the reducibility of nickel species and the interaction between nickel species and alumina. The catalytic hydrogenation of p-nitrophenol to p-aminophenol was investigated over the prepared nickel-based xerogel catalysts. The conversion of p-nitrophenol was monitored by UV spectrophotometry and high performance liquid chromatography (HPLC). The results show that the catalysts are highly selective for the conversion of p-nitrophenol to p-aminophenol and the order of catalytic activities of the catalysts is Ni < Ni-Al{sub 2}O{sub 3} < Ni-Ca-Al{sub 2}O{sub 3}. The catalysts were recycled and were used to evaluate the reutilization.

  12. Temperature modulation of a catalytic gas sensor.

    Science.gov (United States)

    Brauns, Eike; Morsbach, Eva; Kunz, Sebastian; Baeumer, Marcus; Lang, Walter

    2014-10-29

    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, additional information about the gas characteristics can be measured and drift effects caused by material shifting or environmental temperature changes can be avoided. In this work a miniaturized catalytic gas sensor which offers a very short response time (electronic device was developed, since theory shows that harmonics induced by the electronics must be avoided to generate a comprehensible signal.

  13. Porous media for catalytic renewable energy conversion

    Science.gov (United States)

    Hotz, Nico

    2012-05-01

    A novel flow-based method is presented to place catalytic nanoparticles into a reactor by sol-gelation of a porous ceramic consisting of copper-based nanoparticles, silica sand, ceramic binder, and a gelation agent. This method allows for the placement of a liquid precursor containing the catalyst into the final reactor geometry without the need of impregnating or coating of a substrate with the catalytic material. The so generated foam-like porous ceramic shows properties highly appropriate for use as catalytic reactor material, e.g., reasonable pressure drop due to its porosity, high thermal and catalytic stability, and excellent catalytic behavior. The catalytic activity of micro-reactors containing this foam-like ceramic is tested in terms of their ability to convert alcoholic biofuel (e.g. methanol) to a hydrogen-rich gas mixture with low concentrations of carbon monoxide (up to 75% hydrogen content and less than 0.2% CO, for the case of methanol). This gas mixture is subsequently used in a low-temperature fuel cell, converting the hydrogen directly to electricity. A low concentration of CO is crucial to avoid poisoning of the fuel cell catalyst. Since conventional Polymer Electrolyte Membrane (PEM) fuel cells require CO concentrations far below 100 ppm and since most methods to reduce the mole fraction of CO (such as Preferential Oxidation or PROX) have CO conversions of up to 99%, the alcohol fuel reformer has to achieve initial CO mole fractions significantly below 1%. The catalyst and the porous ceramic reactor of the present study can successfully fulfill this requirement.

  14. Gas-solid catalytic reactions over ruthenium-based catalysts%钌基催化剂催化的气固相反应

    Institute of Scientific and Technical Information of China (English)

    施文博; 刘霄龙; 曾俊淋; 王健; 魏耀东; 朱廷钰

    2016-01-01

    防止高温焙烧导致催化剂烧结.对于 HCl氧化虽然研究较少,但是 Over等人对 HCl氧化机理进行了深入研究,并且日本住友化工设计的 Ru基催化剂已经商业化. Ru基催化剂可以有效降低甲烷部分氧化的反应温度和压力,并具有高的选择性和稳定性,避免副产物生成.现有催化系统以及新型催化剂开发仍面临诸多挑战,例如:对于单一 VOC氧化过程和多元 VOCs催化氧化的机理和动力学需要进一步研究;对于氨合成需要寻求具有高电导率的载体,从而将电子快速转移到 Ru颗粒表面,使得氨合成在更低温度下进行;为了避免副产物生成,需确保新型 Ru基催化剂上PROX和甲烷部分氧化在低温低压条件下进行; Ru基催化剂理化性质对活性的影响以及失活等问题需要进一步研究.%Ruthenium (Ru)‐based catalysts are widely employed in several types of gas‐solid reactions because of their high catalytic activities. This review provides theoretical research on Ru‐based catalysts and an analysis of their basic properties and oxidation behavior. There is particular emphasis on Ru‐catalyzed gas‐solid catalytic reactions, including the catalytic oxidation of VOCs, preferential oxidation of CO, synthesis of ammonia, oxidation of HCl and partial oxidation of CH4. Recent litera‐ture on catalysis is summarized and compared. Finally, we describe current challenges in the field and propose approaches for future development of Ru‐based catalysts.

  15. Glu311 and Arg337 Stabilize a Closed Active-site Conformation and Provide a Critical Catalytic Base and Countercation for Green Bioluminescence in Beetle Luciferases.

    Science.gov (United States)

    Viviani, V R; Simões, A; Bevilaqua, V R; Gabriel, G V M; Arnoldi, F G C; Hirano, T

    2016-08-30

    Beetle luciferases elicit the emission of different bioluminescence colors from green to red. Whereas firefly luciferases emit yellow-green light and are pH-sensitive, undergoing a typical red-shift at acidic pH and higher temperatures and in the presence of divalent heavy metals, click beetle and railroadworm luciferases emit a wider range of colors from green to red but are pH-independent. Despite many decades of study, the structural determinants and mechanisms of bioluminescence colors and pH sensitivity remain enigmatic. Here, through modeling studies, site-directed mutagenesis, and spectral and kinetic studies using recombinant luciferases from the three main families of bioluminescent beetles that emit different colors of light (Macrolampis sp2 firefly, Phrixotrix hirtus railroadworm, and Pyrearinus termitilluminans click beetle), we investigated the role of E311 and R337 in bioluminescence color determination. All mutations of these residues in firefly luciferase produced red mutants, indicating that the preservation of opposite charges and the lengths of the side chains of E311 and R337 are essential for keeping a salt bridge that stabilizes a closed hydrophobic conformation favorable for green light emission. Kinetic studies indicate that residue R337 is important for binding luciferin and creating a positively charged environment around excited oxyluciferin phenolate. In Pyrearinus green-emitting luciferase, the R334A mutation causes a 27 nm red-shift, whereas in Phrixotrix red-emitting luciferase, the L334R mutation causes a blue-shift that is no longer affected by guanidine. These results provide compelling evidence that the presence of arginine at position 334 is essential for blue-shifting the emission spectra of most beetle luciferases. Therefore, residues E311 and R337 play both structural and catalytic roles in bioluminescence color determination, by stabilizing a closed hydrophobic conformation favorable for green light emission, and also

  16. Nonaqueous catalytic fluorometric trace determination of vanadium based on the pyronine B-hydrogen peroxide reaction and flow injection after cloud point extraction.

    Science.gov (United States)

    Paleologos, E K; Koupparis, M A; Karayannis, M I; Veltsistas, P G

    2001-09-15

    The catalytic effect of vanadium on the pyronine B-H2O2 system is examined. Enhancement of the catalytic reaction rate along with the efficiency and selectivity against vanadium is achieved in a formic acid environment in the presence of a nonionic surfactant (Triton X-114). Elimination of drastic interference caused by inorganic acids and aqueous matrix along with a 50-fold preconcentration of vanadium are facilitated through cloud point extraction of its neutral complex with 8-quinolinol in an acidic solution. Subsequent flow injection analysis (FIA) with fluorometric detection renders the proposed method ideal for selective and cost-effective determination of as little as 0.020 microng L(-1) vanadium in environmental, biological, and food substrates. The preconcentration step can be applied simultaneously to multiple samples, allowing for massive preparation prior to analysis, compensating, thus, for the time-consuming procedure.

  17. Promotional effects of cerium doping and NOx on the catalytic soot combustion over MnMgAlO hydrotalcite-based mixed oxides

    Institute of Scientific and Technical Information of China (English)

    李倩; 王晓; 常伟; 陈慧; 张昭良

    2014-01-01

    A series of MnMgAlO samples with different amounts of Ce doping were facilely prepared using coprecipitation method and their catalytic soot combustion activity was evaluated by temperature programmed oxidation reaction (TPO). The methods of X-ray diffraction (XRD), Brumauer-Emmett-Teller (BET), H2-TPR, NO-TPO and in situ IR were used to characterize the physio-chemical properties of these samples. Dopant Ce improved the soot combustion performance of MnMgAlO catalyst due to the en-hanced redox ability. Introduction of NOx led to the further increase of catalytic soot oxidation activity on these samples. Over Ce-containing samples, the catalytic activity was slightly decreased as the amount of dopant Ce increased in O2. Differently, in NO+O2, a certain amount of dopant Ce was much more favorable and excess amount of Ce resulted in a sharp drop of the catalytic soot combustion activity. Both NO2 and nitrates were found to have great contributions to the effects of NOx on the soot combustion activity of Ce-doped catalysts. More NO2 was generated as dopant Ce increased. When appropriate amount of Ce was introduced, the as-formed NO2 was stored as bridging bidentate nitrate on Mn-Ce site, which was confirmed to have higher reactivity with soot than nitrite or monodentate nitrate on Mn and/or Ce sites. Overall, Mn0.5Mg2.5Ce0.1Al0.9O was considered as the most potential catalyst for soot combustion.

  18. Catalytic processes for space station waste conversion

    Science.gov (United States)

    Schoonover, M. W.; Madsen, R. A.

    1986-01-01

    Catalytic techniques for processing waste products onboard space vehicles were evaluated. The goal of the study was the conversion of waste to carbon, wash water, oxygen and nitrogen. However, the ultimate goal is conversion to plant nutrients and other materials useful in closure of an ecological life support system for extended planetary missions. The resulting process studied involves hydrolysis at 250 C and 600 psia to break down and compact cellulose material, distillation at 100 C to remove water, coking at 450 C and atmospheric pressure, and catalytic oxidation at 450 to 600 C and atmospheric pressure. Tests were conducted with a model waste to characterize the hydrolysis and coking processes. An oxidizer reactor was sized based on automotive catalytic conversion experience. Products obtained from the hydrolysis and coking steps included a solid residue, gases, water condensate streams, and a volatile coker oil. Based on the data obtained, sufficient component sizing was performed to make a preliminary comparison of the catalytic technique with oxidation for processing waste for a six-man spacecraft. Wet oxidation seems to be the preferred technique from the standpoint of both component simplicity and power consumption.

  19. 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.

  20. A model of protocell based on the introduction of a semi-permeable membrane in a stochastic model of catalytic reaction networks

    Directory of Open Access Journals (Sweden)

    Marco Villani

    2013-09-01

    Full Text Available In this work we introduce some preliminary analyses on the role of a semi-permeable membrane in the dynamics of a stochastic model of catalytic reaction sets (CRSs of molecules. The results of the simulations performed on ensembles of randomly generated reaction schemes highlight remarkable differences between this very simple protocell description model and the classical case of the continuous stirred-tank reactor (CSTR. In particular, in the CSTR case, distinct simulations with the same reaction scheme reach the same dynamical equilibrium, whereas, in the protocell case, simulations with identical reaction schemes can reach very different dynamical states, despite starting from the same initial conditions.

  1. Pd(II and Zn(II Based Complexes with Schiff Base Ligands: Synthesis, Characterization, Luminescence, and Antibacterial and Catalytic Activities

    Directory of Open Access Journals (Sweden)

    Zhi-Qiang Feng

    2013-01-01

    Full Text Available Two new metal complexes involving Schiff base ligands, namely, [Pd(L12] (1 and [Zn(L22] (2, [HL1: 2,4-dibromo-6-((E-(mesityliminomethylphenol and HL2: 2-((E-(2,6-diisopropylphenyliminomethyl-4,6-dibromophenol], have been solvothermally synthesized and characterized by elemental analysis, IR-spectroscopy, thermogravimetric analysis, powder X-ray diffraction, and single-crystal X-ray diffraction. Both 1 and 2 are mononuclear cyclometalated complexes with square planar and tetrahedral coordination geometry, respectively. 1 and 2 display photoluminescence in the solid state at 298 K (fluorescence lifetimes τ = 5.521 μs at 508 nm for 1; τ = 3.697 μs at 506 nm for 2. These Schiff base ligands and their metal complexes have been screened for antibacterial activity against several bacteria strains, and the results are compared with the activity of penicillin. Moreover, the Suzuki reaction of 4-bromoanisole with phenylboronic acid by 1 has also been studied.

  2. HYDROGEN TRANSFER IN CATALYTIC CRACKING

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    Hydrogen transfer is an important secondary reaction of catalytic cracking reactions, which affects product yield distribution and product quality. It is an exothermic reaction with low activation energy around 43.3 kJ/mol. Catalyst properties and operation parameters in catalytic cracking greatly influence the hydrogen transfer reaction. Satisfactory results are expected through careful selection of proper catalysts and operation conditions.

  3. Catalytic quantum error correction

    CERN Document Server

    Brun, T; Hsieh, M H; Brun, Todd; Devetak, Igor; Hsieh, Min-Hsiu

    2006-01-01

    We develop the theory of entanglement-assisted quantum error correcting (EAQEC) codes, a generalization of the stabilizer formalism to the setting in which the sender and receiver have access to pre-shared entanglement. Conventional stabilizer codes are equivalent to dual-containing symplectic codes. In contrast, EAQEC codes do not require the dual-containing condition, which greatly simplifies their construction. We show how any quaternary classical code can be made into a EAQEC code. In particular, efficient modern codes, like LDPC codes, which attain the Shannon capacity, can be made into EAQEC codes attaining the hashing bound. In a quantum computation setting, EAQEC codes give rise to catalytic quantum codes which maintain a region of inherited noiseless qubits. We also give an alternative construction of EAQEC codes by making classical entanglement assisted codes coherent.

  4. Catalytic Combustion of Gasified Waste

    Energy Technology Data Exchange (ETDEWEB)

    Kusar, Henrik

    2003-09-01

    This thesis concerns catalytic combustion for gas turbine application using a low heating-value (LHV) gas, derived from gasified waste. The main research in catalytic combustion focuses on methane as fuel, but an increasing interest is directed towards catalytic combustion of LHV fuels. This thesis shows that it is possible to catalytically combust a LHV gas and to oxidize fuel-bound nitrogen (NH{sub 3}) directly into N{sub 2} without forming NO{sub x} The first part of the thesis gives a background to the system. It defines waste, shortly describes gasification and more thoroughly catalytic combustion. The second part of the present thesis, paper I, concerns the development and testing of potential catalysts for catalytic combustion of LHV gases. The objective of this work was to investigate the possibility to use a stable metal oxide instead of noble metals as ignition catalyst and at the same time reduce the formation of NO{sub x} In paper II pilot-scale tests were carried out to prove the potential of catalytic combustion using real gasified waste and to compare with the results obtained in laboratory scale using a synthetic gas simulating gasified waste. In paper III, selective catalytic oxidation for decreasing the NO{sub x} formation from fuel-bound nitrogen was examined using two different approaches: fuel-lean and fuel-rich conditions. Finally, the last part of the thesis deals with deactivation of catalysts. The various deactivation processes which may affect high-temperature catalytic combustion are reviewed in paper IV. In paper V the poisoning effect of low amounts of sulfur was studied; various metal oxides as well as supported palladium and platinum catalysts were used as catalysts for combustion of a synthetic gas. In conclusion, with the results obtained in this thesis it would be possible to compose a working catalytic system for gas turbine application using a LHV gas.

  5. Feed Quality and Its Effect on the Performance of the Fluid Catalytic Cracking Unit (A Case Study of Nigerian Based Oil Company

    Directory of Open Access Journals (Sweden)

    Abubakar Garba ISAH

    2006-07-01

    Full Text Available This paper presents results of the study of feed quality and its effect on the performance of the fluid catalytic cracking unit using Port-Harcourt Refinery Company (PHRC as a case study. The important feed qualities used are the hydrocarbon content and a hydrotreated feed. Data on the feed properties used in PHRC were collected and a product mass balance was carried out on the fluid catalytic cracking unit. Conversion and gasoline yield of the unit were found to be 73.43 vol% and 52.07 vol% respectively. On comparison with cracking of aromatic feed, from literature, with 61.3 vol% conversion and 45.64 vol% gasoline yields, the feed is said to be paraffinic because of its higher conversion and gasoline yield. On comparison with that collected for hydrotreated feed, 80.62 vol% conversion and 63.9 vol% gasoline yield, it is concluded that feed hydrotreating increases conversion and gasoline yield by a significant amount.

  6. Deactivation Mechanisms of Base Metal/Zeolite Urea Selective Catalytic Reduction Materials, and Development of Zeolite-Based Hydrocarbon Adsorber Materials

    Energy Technology Data Exchange (ETDEWEB)

    Gao, Feng; Kwak, Ja Hun; Lee, Jong H.; Tran, Diana N.; Peden, Charles HF; Howden, Ken; Cheng, Yisun; Lupescu, Jason; Cavattaio, Giovanni; Lambert, Christine; McCabe, Robert W.

    2012-12-31

    In this collaborative program, scientists and engineers in the Institute for Integrated Catalysis at Pacific Northwest National Laboratory and at Ford Motor Company have investigated laboratory- and engine-aged SCR catalysts, containing mainly base metal zeolites. These studies are leading to a better understanding of various aging factors that impact the long-term performance of SCR catalysts and improve the correlation between laboratory and engine aging, saving experimental time and cost. We have also studied materials effective for the temporary storage of HC species during the cold-start period. In particular, we have examined the adsorption and desorption of various HC species produced during the combustion with different fuels (e.g., gasoline, E85, diesel) over potential HC adsorber materials, and measured the kinetic parameters to update Ford’s HC adsorption model. Since this CRADA has now been completed, in this annual report we will provide very brief summaries of most of the work carried out on this CRADA over the last several years.

  7. Deactivation Mechanisms of Base Metal/Zeolite Urea Selective Catalytic Reduction Materials, and Development of Zeolite-Based Hydrocarbon Adsorber Materials

    Energy Technology Data Exchange (ETDEWEB)

    Kwak, Ja Hun; Lee, Jong H.; Kim, Do Heui; Li, Xiaohong S.; Tran, Diana N.; Peden, Charles HF

    2011-12-22

    This annual report describes recent progress on a collaborative project between scientists and engineers in the Institute for Integrated Catalysis at PNNL and at Ford Motor Company, involving investigations of laboratory- and engine-aged SCR catalysts, containing mainly base metal zeolites. These studies are leading to a better understanding of various aging factors that impact the long-term performance of SCR catalysts and improve the correlation between laboratory and engine aging, saving experimental time and cost. We are investigating SCR catalysts with reduced ammonia slip, increased low temperature activity, and increased product selectivity to N2. More recent recognition that high temperature performance, under regimes that sometimes cause deactivation, also needs to be improved is driving current work focused on catalyst materials modifications needed to achieve this enhanced performance. We are also studying materials effective for the temporary storage of HC species during the cold-start period. In particular, we examine the adsorption and desorption of various HC species produced during the combustion with different fuels (e.g., gasoline, E85, diesel) over potential HC adsorber materials, and measure the kinetic parameters to update Ford’s HC adsorption model.

  8. Application of tungsten-based catalytic materials to direct alcohol fuel cell production%钨基催化材料在直接醇类燃料电池中的应用研究

    Institute of Scientific and Technical Information of China (English)

    刘喜慧; 周阳; 梁福永; 曲慧男; 温和瑞

    2015-01-01

    直接醇类燃料电池(DAFC)具有能量密度高、携带方便以及环境友好等优点。电极催化剂是改善DAFC性能的关键材料,目前DAFC催化剂要解决的关键问题是提高催化剂的电催化活性、抗CO等中间产物毒化能力以及降低催化剂成本,文中综述了2种钨基催化材料的制备、性能表征及其在DAFC中的应用研究进展,指出了目前钨基复合催化剂需要重点研究的基础问题。%Direct alcohol fuel cell (DAFC) has the advantages of high energy density , convenient packaging and environment friendliness. The key problem of anode catalyst for DAFC is how to improve the catalytic activity of anodic oxidation, and enhance the ability of resistance to CO poisoning and lower the price of catalyst. This paper reviews the synthesis , electric catalytic properties and applications in DAFC of two kinds of tungsten-based catalysts. The existing basic problems of tungsten-based composite catalysts are proposed.

  9. Halogen Chemistry on Catalytic Surfaces.

    Science.gov (United States)

    Moser, Maximilian; Pérez-Ramírez, Javier

    2016-01-01

    Halogens are key building blocks for the manufacture of high-value products such as chemicals, plastics, and pharmaceuticals. The catalytic oxidation of HCl and HBr is an attractive route to recover chlorine and bromine in order to ensure the sustainability of the production processes. Very few materials withstand the high corrosiveness and the strong exothermicity of the reactions and among them RuO2 and CeO2-based catalysts have been successfully applied in HCl oxidation. The search for efficient systems for HBr oxidation was initiated by extrapolating the results of HCl oxidation based on the chemical similarity of these reactions. Interestingly, despite its inactivity in HCl oxidation, TiO2 was found to be an outstanding HBr oxidation catalyst, which highlighted that the latter reaction is more complex than previously assumed. Herein, we discuss the results of recent comparative studies of HCl and HBr oxidation on both rutile-type (RuO2, IrO2, and TiO2) and ceria-based catalysts using a combination of advanced experimental and theoretical methods to provide deeper molecular-level understanding of the reactions. This knowledge aids the design of the next-generation catalysts for halogen recycling.

  10. 'Click' generated 1,2,3-triazole based organosulfur/selenium ligands and their Pd(ii) and Ru(ii) complexes: their synthesis, structure and catalytic applications.

    Science.gov (United States)

    Kumar, Satyendra; Saleem, Fariha; Singh, Ajai K

    2016-07-28

    1-(2,6-Diisopropylphenyl)-4-(phenylthio/selenomethyl)-1H-1,2,3-triazole (L1/L2) was synthesized by a 'Click' reaction and treated with [Pd(CH3CN)2Cl2] for 5 h or [(η(6)-C6H6)RuCl(μ-Cl)]2 for 8 h (followed by reaction with NH4PF6) at room temperature, resulting in complexes [Pd(L)Cl2] (1 and 2) or [(η(6)-C6H6)Ru(L)Cl]PF6 (3 and 4) (L = L1 or L2), respectively. The four complexes (1-4) and ligands (L1 and L2) were characterized with (1)H, (13)C{(1)H} and (77)Se{(1)H} NMR spectroscopy and high resolution mass spectrometry. The single crystal structures of 1-4 were solved. The geometry of Pd in 1 and 2 is distorted square planar. The Pd-S and Pd-Se bond distances in 1 and 2 are 2.277(3) and 2.384(6) Å respectively. In 3 and 4, there is a pseudo-octahedral "piano-stool" type disposition of donor atoms around Ru. The Ru-S and Ru-Se bond lengths in 3 and 4 are 2.3728(12) and 2.4741(6) Å respectively. The catalytic activity of complexes 1 and 2 was explored for Suzuki-Miyaura coupling (SMC) in water and the Sonogashira coupling reaction. For various aryl bromides, including deactivated ones, complexes 1 and 2 were found to be efficient catalysts for both couplings. The optimum loading of 1 and 2 required to catalyze both coupling reactions is of the order of 0.001-2 mol% of Pd. For SMC, no additive or phase transfer catalyst was added. For catalysis of the transfer hydrogenation (TH) of aldehydes and ketones, the half-sandwich Ru(ii) complexes 3 and 4 were explored. Their optimum catalytic loading was found to be 0.1-0.4 mol% of Ru. For TH, both the water solvent and the glycerol hydrogen source are environmentally friendly. The catalytic efficiencies of 3 and 4 are comparable with those reported for other catalysts for TH carried out with 2-propanol or glycerol as a H-source. 1, with a sulfur ligand, is more efficient than 2 (Se analog) for both SMC and the Sonogashira coupling. The activities of 3 and 4 for TH are in the order Se > S.

  11. Control of a catalytic fluid cracker

    Energy Technology Data Exchange (ETDEWEB)

    Arbel, A.; Huang, Z.; Rinard, I.; Shinnar, R.

    1993-12-13

    Control offers an important tool for savings in refineries, mainly by integration of process models into on-line control. This paper is part of a research effort to better understand problems of partial control; control of a Fluid Catalytic Cracker (FCC) is used as example. Goal is to understand better the control problems of an FCC in context of model based control of a refinery, and to understand the general problem of designing partial control systems.

  12. Inlfuence of the Alkali Treatment of HZSM-5 Zeolite on Catalytic Performance of PtSn-Based Catalyst for Propane Dehydrogenation

    Institute of Scientific and Technical Information of China (English)

    Huang Li; Zhou Shijian; Zhou Yuming; Zhang Yiwei; Xu Jun; Wang Li

    2013-01-01

    The porous material ATZ with micro-mesopore hierarchical porosity was prepared by alkali treatment of parent HZSM-5 zeolite and applied for propane dehydrogenation. The zeolite samples were characterized by XRD, N2-physisorption, and NH3-TPD analysis. The results showed that the alkali treatment can modify the physicochemical prop-erties of HZSM-5 zeolite. In this case, the porous material ATZ showed larger external surface area with less acid sites as compared to the HZSM-5 zeolite. It was found out that the alkali treatment of HZSM-5 zeolite could promote the catalytic performance of PtSn/ATZ catalyst. The possible reason was ascribed to the low acidity of ATZ. Furthermore, the presence of mesopores could reduce the carbon deposits on the metallic surface, which was also favorable for the dehydrogenation reaction.

  13. Numerical Study of Passive Catalytic Recombiner for Hydrogen Mitigation

    Directory of Open Access Journals (Sweden)

    Pavan K Sharma

    2010-10-01

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

  14. Porous protein crystals as catalytic vessels for organometallic complexes.

    Science.gov (United States)

    Tabe, Hiroyasu; Abe, Satoshi; Hikage, Tatsuo; Kitagawa, Susumu; Ueno, Takafumi

    2014-05-01

    Porous protein crystals, which are protein assemblies in the solid state, have been engineered to form catalytic vessels by the incorporation of organometallic complexes. Ruthenium complexes in cross-linked porous hen egg white lysozyme (HEWL) crystals catalyzed the enantioselective hydrogen-transfer reduction of acetophenone derivatives. The crystals accelerated the catalytic reaction and gave different enantiomers based on the crystal form (tetragonal or orthorhombic). This method represents a new approach for the construction of bioinorganic catalysts from protein crystals.

  15. Northwestern University Facility for Clean Catalytic Process Research

    Energy Technology Data Exchange (ETDEWEB)

    Marks, Tobin Jay [Northwestern University

    2013-05-08

    Northwestern University with DOE support created a Facility for Clean Catalytic Process Research. This facility is designed to further strengthen our already strong catalysis research capabilities and thus to address these National challenges. Thus, state-of-the art instrumentation and experimentation facility was commissioned to add far greater breadth, depth, and throughput to our ability to invent, test, and understand catalysts and catalytic processes, hence to improve them via knowledge-based design and evaluation approaches.

  16. Hydrogénations catalytiques. De la recherche de base à l'application industrielle Catalytic Hydrogenation from Basic Research to Industrial Applications

    Directory of Open Access Journals (Sweden)

    Boitiaux J. P.

    2006-11-01

    Full Text Available Les premiers travaux concernant l'hydrogénation catalytique ont montré la spécificité des différents métaux pour les différents types d'hydrogénation (acétyléniques, oléfines, aromatiques, aldéhydes, nitriles. . . . Cette observation incluait de façon encore vague la notion de l'importance du couple métal-substrat. Une contradiction avec le caractère non sensible à la structure de ces réactions apparaissait alors. Des travaux récents effectués sur des catalyseurs au palladium de dispersions variées ont clairement démontré l'influence de la taille de particule sur la vitesse d'hydrogénation des acétyléniques et dioléfines en C4. Un tel comportement a été depuis confirmé par d'autres travaux sur palladium, platine et rhodium. Le phénomène est dû à une adsorption trop forte des réactifs sur les petites particules : celles-ci sont électrodéficientes et adsorbent très fortement les composés électrodonneurs comme les hydrocarbures insaturés. L'explication est confirmée par l'effet additif que produit la pipéridine. Sa coadsorption sur le catalyseur déstabilise la liaison métal-substrat et augmente l'activité. Une étude cinétique complète a permis d'affiner cette interprétation en démontrant la constance de l'activité intrinsèque et la relation entre la sensibilité à la dispersion métallique et une complexation du site métallique du type de celle que l'on rencontre sur les catalyseurs homogènes. Ces études fondamentales ont des conséquences très importantes pour la mise au point des catalyseurs industriels : pour chaque procédé, et donc pour chaque hydrogénation, il est nécessaire de déterminer la dispersion optimale du métal pour obtenir l'activité et la sélectivité les plus élevées, c'est-à-dire la meilleure rentabilité du procédé. Par ailleurs, les concepts établis grâce à ces recherches de base permettent d'unifier l'interprétation de l'influence des solvants, des

  17. Molecular Recognition of the Catalytic Zinc(II) Ion in MMP-13: Structure-Based Evolution of an Allosteric Inhibitor to Dual Binding Mode Inhibitors with Improved Lipophilic Ligand Efficiencies.

    Science.gov (United States)

    Fischer, Thomas; Riedl, Rainer

    2016-03-01

    Matrix metalloproteinases (MMPs) are a class of zinc dependent endopeptidases which play a crucial role in a multitude of severe diseases such as cancer and osteoarthritis. We employed MMP-13 as the target enzyme for the structure-based design and synthesis of inhibitors able to recognize the catalytic zinc ion in addition to an allosteric binding site in order to increase the affinity of the ligand. Guided by molecular modeling, we optimized an initial allosteric inhibitor by addition of linker fragments and weak zinc binders for recognition of the catalytic center. Furthermore we improved the lipophilic ligand efficiency (LLE) of the initial inhibitor by adding appropriate zinc binding fragments to lower the clogP values of the inhibitors, while maintaining their potency. All synthesized inhibitors showed elevated affinity compared to the initial hit, also most of the novel inhibitors displayed better LLE. Derivatives with carboxylic acids as the zinc binding fragments turned out to be the most potent inhibitors (compound 3 (ZHAWOC5077): IC50 = 134 nM) whereas acyl sulfonamides showed the best lipophilic ligand efficiencies (compound 18 (ZHAWOC5135): LLE = 2.91).

  18. Catalytic Membrane Sensors

    Energy Technology Data Exchange (ETDEWEB)

    Boyle, T.J.; Brinker, C.J.; Gardner, T.J.; Hughes, R.C.; Sault, A.G.

    1998-12-01

    The proposed "catalytic membrane sensor" (CMS) was developed to generate a device which would selectively identify a specific reagent in a complex mixture of gases. This was to be accomplished by modifying an existing Hz sensor with a series of thin films. Through selectively sieving the desired component from a complex mixture and identifying it by decomposing it into Hz (and other by-products), a Hz sensor could then be used to detect the presence of the select component. The proposed "sandwich-type" modifications involved the deposition of a catalyst layered between two size selective sol-gel layers on a Pd/Ni resistive Hz sensor. The role of the catalyst was to convert organic materials to Hz and organic by-products. The role of the membraneo was to impart both chemical specificity by molecukir sieving of the analyte and converted product streams, as well as controlling access to the underlying Pd/Ni sensor. Ultimately, an array of these CMS elements encompassing different catalysts and membranes were to be developed which would enable improved selectivity and specificity from a compiex mixture of organic gases via pattern recognition methodologies. We have successfully generated a CMS device by a series of spin-coat deposited methods; however, it was determined that the high temperature required to activate the catalyst, destroys the sensor.

  19. Catalytic gasification of biomass

    Science.gov (United States)

    Robertus, R. J.; Mudge, L. K.; Sealock, L. J., Jr.; Mitchell, D. H.; Weber, S. L.

    1981-12-01

    Methane and methanol synthesis gas can be produced by steam gasification of biomass in the presence of appropriate catalysts. This concept is to use catalysts in a fluidized bed reactor which is heated indirectly. The objective is to determine the technical and economic feasibility of the concept. Technically the concept has been demonstrated on a 50 lb per hr scale. Potential advantages over conventional processes include: no oxygen plant is needed, little tar is produced so gas and water treatment are simplified, and yields and efficiencies are greater than obtained by conventional gasification. Economic studies for a plant processing 2000 T/per day dry wood show that the cost of methanol from wood by catalytic gasification is competitive with the current price of methanol. Similar studies show the cost of methane from wood is competitive with projected future costs of synthetic natural gas. When the plant capacity is decreased to 200 T per day dry wood, neither product is very attractive in today's market.

  20. Catalytic cracking of lignites

    Energy Technology Data Exchange (ETDEWEB)

    Seitz, M.; Nowak, S.; Naegler, T.; Zimmermann, J. [Hochschule Merseburg (Germany); Welscher, J.; Schwieger, W. [Erlangen-Nuernberg Univ. (Germany); Hahn, T. [Halle-Wittenberg Univ., Halle (Germany)

    2013-11-01

    A most important factor for the chemical industry is the availability of cheap raw materials. As the oil price of crude oil is rising alternative feedstocks like coal are coming into focus. This work, the catalytic cracking of lignite is part of the alliance ibi (innovative Braunkohlenintegration) to use lignite as a raw material to produce chemicals. With this new one step process without an input of external hydrogen, mostly propylene, butenes and aromatics and char are formed. The product yield depends on manifold process parameters. The use of acid catalysts (zeolites like MFI) shows the highest amount of the desired products. Hydrogen rich lignites with a molar H/C ratio of > 1 are to be favoured. Due to primary cracking and secondary reactions the ratio between catalyst and lignite, temperature and residence time are the most important parameter to control the product distribution. Experiments at 500 C in a discontinuous rotary kiln reactor show yields up to 32 wt-% of hydrocarbons per lignite (maf - moisture and ash free) and 43 wt-% char, which can be gasified. Particularly, the yields of propylene and butenes as main products can be enhanced four times to about 8 wt-% by the use of catalysts while the tar yield decreases. In order to develop this innovative process catalyst systems fixed on beads were developed for an easy separation and regeneration of the used catalyst from the formed char. (orig.)

  1. Development of Catalytic Cooking Plates

    Energy Technology Data Exchange (ETDEWEB)

    Hjelm, Anna-Karin; Silversand, Fredrik [CATATOR AB, Lund (Sweden); Tena, Emmanuel; Berger, Marc [Gaz de France (France)

    2004-04-01

    Gas catalytic combustion for gas stoves or cooking plates (closed catalytic burner system with ceramic plates) is a very promising technique in terms of ease of cleaning, power modulation and emissions. Previous investigations show that wire mesh catalysts, prepared and supplied by Catator AB (CAT), seem to be very well suited for such applications. Beside significantly reducing the NOx-emissions, these catalysts offer important advantages such as good design flexibility, low pressure drop and high heat transfer capacity, where the latter leads to a quick thermal response. Prior to this project, Gaz de France (GdF) made a series of measurements with CAT's wire mesh catalysts in their gas cooking plates and compared the measured performance with similar results obtained with theirs cordierite monolith catalysts. Compared to the monolith catalyst, the wire mesh catalyst was found to enable very promising results with respect to both emission levels (<10 mg NO{sub x} /kWh, <5 mg CO/kWh) and life-time (>8000 h vs. 700 h at 200 kW/m{sup 2}). It was however established that the radiation and hence, the thermal efficiency of the cooking plate, was significantly less than is usually measured in combination with the monolith (15 % vs. 32 %). It was believed that the latter could be improved by developing new burner designs based on CAT's wire mesh concept. As a consequence, a collaboration project between GdF, CAT and the Swedish Gas Technology AB was created. This study reports on the design, the construction and the evaluation of new catalytic burners, based on CAT's wire mesh catalysts, used for the combustion of natural gas in gas cooking stoves. The evaluation of the burners was performed with respect to key factors such as thermal efficiency, emission quality and pressure drop, etc, by the use of theoretical simulations and experimental tests. Impacts of parameters such as the the wire mesh number, the wire mesh structure (planar or folded), the

  2. Immigration process in catalytic medium

    Institute of Scientific and Technical Information of China (English)

    洪文明; 王梓坤

    2000-01-01

    The longtime behavior of the immigration process associated with a catalytic super-Brown-ian motion is studied. A large number law is proved in dimension d≤3 and a central limit theorem is proved for dimension d = 3.

  3. Immigration process in catalytic medium

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    The longtime behavior of the immigration process associated with a catalytic super-Brownian motion is studied. A large number law is proved in dimension d≤3 and a central limit theorem is proved for dimension d=3.

  4. Highly sensitive catalytic spectrophotometric determination of ruthenium

    Science.gov (United States)

    Naik, Radhey M.; Srivastava, Abhishek; Prasad, Surendra

    2008-01-01

    A new and highly sensitive catalytic kinetic method (CKM) for the determination of ruthenium(III) has been established based on its catalytic effect on the oxidation of L-phenylalanine ( L-Pheala) by KMnO 4 in highly alkaline medium. The reaction has been followed spectrophotometrically by measuring the decrease in the absorbance at 526 nm. The proposed CKM is based on the fixed time procedure under optimum reaction conditions. It relies on the linear relationship where the change in the absorbance (Δ At) versus added Ru(III) amounts in the range of 0.101-2.526 ng ml -1 is plotted. Under the optimum conditions, the sensitivity of the proposed method, i.e. the limit of detection corresponding to 5 min is 0.08 ng ml -1, and decreases with increased time of analysis. The method is featured with good accuracy and reproducibility for ruthenium(III) determination. The ruthenium(III) has also been determined in presence of several interfering and non-interfering cations, anions and polyaminocarboxylates. No foreign ions interfered in the determination ruthenium(III) up to 20-fold higher concentration of foreign ions. In addition to standard solutions analysis, this method was successfully applied for the quantitative determination of ruthenium(III) in drinking water samples. The method is highly sensitive, selective and very stable. A review of recently published catalytic spectrophotometric methods for the determination of ruthenium(III) has also been presented for comparison.

  5. Recent Progress of Cu-Based Catalysts for Catalytic Elimination of CO%铜基催化剂用于一氧化碳催化消除研究进展

    Institute of Scientific and Technical Information of China (English)

    余强; 高飞; 董林

    2012-01-01

    Catalytic elimination of CO mainly includes complete oxidation (CO-COOX) and preferential oxidation of CO (CO-PROX). First, combined with our group's research, a brief introduction to the active species and the interaction between components in Cu-based catalysts for CO-COOX was presented from the perspective of the catalyst system. Then recent progress in CO-PROX under H2-rich over Cu-based catalysts was systematically summarized. Influence of the preparation method, promoter, and support of CuO-CeO2 catalyst as well as transition metal ions doped support (CuO/Ce1-xMxO2), and inverse structure (CeO2/CuO) on the catalytic performance in CO-PROX was elaborated. Finally, the application problems and future research trend of Cu-based catalysts for catalytic removal of CO were discussed and summarized.%催化消除CO主要包括CO的完全氧化(CO-COOX)和优先氧化(CO-PROX).首先,结合本课题组的相关研究,按照催化剂体系介绍了Cu基催化剂在CO-COOX中的活性物种和组分之间的相互作用.其次,对用于富氢气氛下CO-PROX的Cu基催化剂进行了系统的分类总结,重点阐述了CuO-CeO2催化剂的制备方法、助剂改性、载体调变以及过渡金属离子掺杂(CuO/Ce1-xMxO2)、反相结构(CeO2/CuO)等方面对CO-PROX催化性能的影响.最后,总结了Cu基催化剂在CO-PROX中存在的问题,并展望了未来的研究趋势.

  6. Colorimetric detection of the flux of hydrogen peroxide released from living cells based on the high peroxidase-like catalytic performance of porous PtPd nanorods.

    Science.gov (United States)

    Ge, Shenguang; Liu, Weiyan; Liu, Haiyun; Liu, Fang; Yu, Jinghua; Yan, Mei; Huang, Jiadong

    2015-09-15

    One-dimensional PtPd porous nanorods (PtPd PNRs) were successfully synthesized through a bromide-induced galvanic replacement reaction between Pd nanowires and K2PtCl6. The PtPd PNRs were porous and alloy-structured with Pt/Pd atomic ratio up to 1:1 which were demonstrated by spectroscopic methods. We had also proved that the nanorods could function as peroxidase mimetic for the detection of H2O2, with the detection limit of 8.6 nM and the linear range from 20 nM to 50 mM. The result demonstrated that PtPd PNRs exhibited much higher affinity to H2O2 over other peroxidase mimetics due to synergistically integrating highly catalytic activity of two metals. On the basis of the peroxidase-like activity, the PtPd PNRs were used as a signal transducer to develop a novel and simple colorimetric method for the study of the flux of H2O2 released from living cell. By using 3,3,5,5-tetramethylbenzidine as substrate, the H2O2 concentration could be distinguished by naked-eye observation without any instrumentation or complicated design. The method developed a new platform for a reliable collection of information on cellular reactive oxygen species release. And the nanomaterial could be used as a power tool for a wide range of potential applications in biotechnology and medicine.

  7. Shape and catalytic mechanism of RuO{sub 2} particles at CO oxidation reaction conditions. First-principles based multi-scale modeling

    Energy Technology Data Exchange (ETDEWEB)

    Reuter, Karsten [TU Muenchen (Germany). Lehrstuhl fuer Theoretische Chemie

    2016-11-01

    For model catalyst studies on low-index single-crystal surfaces close agreement between detailed measurements and quantitative microkinetic modeling can increasingly be achieved. However, for 'real' catalyst particles, such structure-morphology-activity relationships are only scarcely established. This is prototypically reflected by the situation for RuO{sub 2}, as a most active catalyst for CO oxidation. Here, existing first-principles kinetic modeling is restricted to just one facet, namely the RuO{sub 2}(110) surface, which is not able to fully account for activity data obtained from polycrystalline RuO{sub 2} powder catalysts. The overarching objective of this project was correspondingly to close this gap and demonstrate that similarly close agreement as for individual single-crystal model catalysts can also be achieved for catalyst particles. Specifically, we addressed experiments where an intact RuO{sub 2} bulk structure is conserved, and establish the atomic-scale structure and reactivity of other RuO{sub 2} low-index facets under the gas-phase conditions characteristic for catalytic CO oxidation.

  8. Structural bases of dimerization of yeast telomere protein Cdc13 and its interaction with the catalytic subunit of DNA polymerase α

    Institute of Scientific and Technical Information of China (English)

    Jia Sun; Neal F Lue; Ming Lei; Yuting Yang; Ke Wan; Ninghui Mao; Tai-Yuan Yu; Yi-Chien Lin; Diane C DeZwaan; Brian C Freeman; Jing-Jer Lin

    2011-01-01

    Budding yeast Cdc13-Stnl-Tenl (CST) complex plays an essential role in telomere protection and maintenance, and has been proposed to be a telomere-specific replication protein A (RPA)-like complex. Previous genetic and structural studies revealed a close resemblance between Stn1-Ten1 and RPA32-RPA14. However, the relationship between Cdc13 and RPA70, the largest subunit of RPA, has remained unclear. Here, we report the crystal structure of the N-terminal OB (oligonucleotide/oligosaccharide binding) fold of Cdc13. Although Cdc13 has an RPA70-like domain organization, the structures of Cdc13 OB folds are significantly different from their counterparts in RPA70, suggesting that they have distinct evolutionary origins. Furthermore, our structural and biochemical analyses revealed unexpected dimerization by the N-terminal OB fold and showed that homodimerization is probably a conserved feature of all Cdc13 proteins. We also uncovered the structural basis of the interaction between the Cdc13 N-terminal OB ' fold and the catalytic subunit of DNA polymerase a (Pol1), and demonstrated a role for Cdc13 dimerization in Pol1 binding. Analysis of the phenotypes of mutants defective in Cdc13 dimerization and Cdc13-Pol1 interaction revealed multiple mechanisms by which dimerization regulates telomere lengths in vivo. Collectively, our findings provide novel insights into the mechanisms and evolution of Cdc13.

  9. Synthesis and Characterization of Graphene and Graphene Oxide Based Palladium Nanocomposites and Their Catalytic Applications in Carbon-Carbon Cross-Coupling Reactions

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Minjae [Kunsan National Univ., Gunsan (Korea, Republic of); Kim, Bohyun; Lee, Yuna; Kim, Beomtae; Park, Joon B. [Chonbuk National Univ., Jeonju (Korea, Republic of)

    2014-07-15

    We have developed an efficient method to generate highly active Pd and PdO nanoparticles (NPs) dispersed on graphene and graphene oxide (GO) by an impregnation method combined with thermal treatments in H{sub 2} and O{sub 2} gas flows, respectively. The Pd NPs supported on graphene (Pd/G) and the PdO NPs supported on GO (PdO/GO) demonstrated excellent carbon-carbon cross-coupling reactions under a solvent-free, environmentally-friendly condition. The morphological and chemical structures of PdO/GO and Pd/G were fully characterized using X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), and transmission electron microscopy (TEM). We found that the remarkable reactivity of the Pd/G and PdO/GO catalysts toward the cross-coupling reaction is attributed to the high degree of dispersion of the Pd and PdO NPs while the oxidative states of Pd and the oxygen functionalities of graphene oxide are not critical for their catalytic performance.

  10. Structural bases of dimerization of yeast telomere protein Cdc13 and its interaction with the catalytic subunit of DNA polymerase [alpha

    Energy Technology Data Exchange (ETDEWEB)

    Sun, Jia; Yang, Yuting; Wan, Ke; Mao, Ninghui; Yu, Tai-Yuan; Lin, Yi-Chien; DeZwaan, Diane C.; Freeman, Brian C.; Lin, Jing-Jer; Lue, Neal F.; Lei, Ming

    2011-08-24

    Budding yeast Cdc13-Stn1-Ten1 (CST) complex plays an essential role in telomere protection and maintenance, and has been proposed to be a telomere-specific replication protein A (RPA)-like complex. Previous genetic and structural studies revealed a close resemblance between Stn1-Ten1 and RPA32-RPA14. However, the relationship between Cdc13 and RPA70, the largest subunit of RPA, has remained unclear. Here, we report the crystal structure of the N-terminal OB (oligonucleotide/oligosaccharide binding) fold of Cdc13. Although Cdc13 has an RPA70-like domain organization, the structures of Cdc13 OB folds are significantly different from their counterparts in RPA70, suggesting that they have distinct evolutionary origins. Furthermore, our structural and biochemical analyses revealed unexpected dimerization by the N-terminal OB fold and showed that homodimerization is probably a conserved feature of all Cdc13 proteins. We also uncovered the structural basis of the interaction between the Cdc13 N-terminal OB fold and the catalytic subunit of DNA polymerase {alpha} (Pol1), and demonstrated a role for Cdc13 dimerization in Pol1 binding. Analysis of the phenotypes of mutants defective in Cdc13 dimerization and Cdc13-Pol1 interaction revealed multiple mechanisms by which dimerization regulates telomere lengths in vivo. Collectively, our findings provide novel insights into the mechanisms and evolution of Cdc13.

  11. Syntheses and molecular structures of novel Ru(II) complexes with bidentate benzimidazole based ligands and their catalytic efficiency for oxidation of benzyl alcohol

    Science.gov (United States)

    Dayan, Osman; Tercan, Melek; Özdemir, Namık

    2016-11-01

    Five bidentate ligands derived from quinoline-2-carboxylic acid, i.e. 2-(1H-benzimidazol-2-yl)quinoline (L1), 2-(1-benzyl-1H-benzimidazol-2-yl)quinoline (L2), 2-[1-(2,3,5,6-tetramethylbenzyl)-1H-benzimidazol-2-yl]quinoline (L3), 2-[1-(4-chlorobenzyl)-1H-benzimidazol-2-yl]quinoline (L4), and 2-[1-(4-methylbenzyl)-1H-benzimidazol-2-yl]quinoline (L5) were synthesized. Treatment of L1-5 with [RuCl2(p-cymene)]2 and KPF6 afforded six-coordinate piano-stool Ru(II) complexes, namely, [RuCl(L1)(p-cymene)]PF6 (C1), [RuCl(L2)(p-cymene)]PF6 (C2), [RuCl(L3)(p-cymene)]PF6 (C3), [RuCl(L4)(p-cymene)]PF6 (C4), and [RuCl(L5)(p-cymene)]PF6 (C5). Synthesized compounds were characterized with different techniques such as 1H and 13C NMR, FT-IR, and UV-vis spectroscopy. The solid state structure of L1 and C3 was confirmed by single-crystal X-ray diffraction analysis. The single crystal structure of C3 verified coordination of L3 to the Ru(II) center. The Ru(II) center has a pseudo-octahedral three legged piano stool geometry. The complexes C1-5 were tested as catalysts for the catalytic oxidation of benzyl alcohol to benzaldehyde in the presence of periodic acid (H5IO6) (Substrate/Catalyst/Oxidant = 1/0.01/0.5). The best result was obtained with C2 (3 h→90%).

  12. Post-treatment of biologically treated wastewater containing organic contaminants using a sequence of H2O2 based advanced oxidation processes: photolysis and catalytic wet oxidation.

    Science.gov (United States)

    Rueda-Márquez, J J; Sillanpää, M; Pocostales, P; Acevedo, A; Manzano, M A

    2015-03-15

    In this paper the feasibility of a multi-barrier treatment (MBT) for the regeneration of synthetic industrial wastewater (SIWW) was evaluated. Industrial pollutants (orange II, phenol, 4-chlorophenol and phenanthrene) were added to the effluent of municipal wastewater treatment plant. The proposed MBT begins with a microfiltration membrane pretreatment (MF), followed by hydrogen peroxide photolysis (H2O2/UVC) and finishing, as a polishing step, with catalytic wet peroxide oxidation (CWPO) using granular activated carbon (GAC) at ambient conditions. During the microfiltration step (0.7 μm) the decrease of suspended solids concentration, turbidity and Escherichia coli in treated water were 88, 94 and 99%, respectively. Also, the effluent's transmittance (254 nm) was increased by 14.7%. Removal of more than 99.9% of all added pollutants, mineralization of 63% of organic compounds and complete disinfection of total coliforms were reached during the H2O2/UVC treatment step (H2O2:TOC w/w ratio = 5 and an UVC average dose accumulated by wastewater 8.80 WUVC s cm(-2)). The power and efficiency of the lamp, the water transmittance and photoreactor geometry are taken into account and a new equation to estimate the accumulated dose in water is suggested. Remaining organic pollutants with a higher oxidation state of carbon atoms (+0.47) and toxic concentration of residual H2O2 were present in the effluent of the H2O2/UVC process. After 2.3 min of contact time with GAC at CWPO step, 90 and 100% of total organic carbon and residual H2O2 were removed, respectively. Also, the wastewater toxicity was studied using Vibrio fischeri and Sparus aurata larvae. The MBT operational and maintenance costs (O&M) was estimated to be 0.59 € m(-3).

  13. 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.

  14. 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....

  15. Synthesis of Nano-sized Yttria via a Sol-Gel Process Based on Hydrated Yttrium Nitrate and Ethylene Glycol and Its Catalytic Performance for Thermal Decomposition of NH4 ClO4

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    Nano-sized yttria particles were synthesized via a non-aqueous sol-gel process based on hydrated yttrium nitrate and ethylene glycol. The effects of the molar ratio of ethylene glycol to yttrium ion and calcination temperature on crystallite size of the products were studied. The catalytic performance of the as-prepared yttria for the ammonium perchlorate (AP) decomposition was investigated by differential scanning calorimetry (DSC). The results indicate that the nano-sized cubic yttria particles with less than 20 nm in average crystallite size can be obtained after 2 h reflux at 70 ℃, dried at 90 ℃, forming xerogel, and followed by annealing of xerogel for 2 h, and that the addition of the nano-sized yttria to AP incorporates two small exothermic peaks of AP in the temperature ranges of 310 ~ 350 ℃ and 400 ~ 470 ℃ into a strong exothermic peak of AP and increases the apparent decomposition heat from 515 to over 1110 J·g-1. It is also clear that the temperature of AP decomposition exothermic peak decreases and the apparent decomposition heat of AP increases with the increase of the amount of nano-sized yttria. The fact that the addition of the 5 % nano-sized yttria to AP decreases the temperature of AP exothermic peak to 337.7 ℃ by reduction of 114.6 ℃ and increases the apparent decomposition heat from 515 to 1240 J·g-1, reveals that nano-sized yttria shows strong catalytic property for AP thermal decomposition.

  16. Synthesis, characterization and catalytic performance of supported solid base catalyst of KOH/SBA-15%KOH/SBA-15负载型固体碱催化剂的合成、表征及催化性能

    Institute of Scientific and Technical Information of China (English)

    朱明明; 万庆宇; 宋芊慧; 蔡天凤; 李会鹏; 赵华

    2013-01-01

    采用后合成法制备出固体碱催化剂KOH/SBA-15,利用X射线衍射法(XRD)、N2吸附-脱附(BET)、透射电镜(TEM)、化学吸附剂表面碱性测定(CO2-TPD)等对其进行表征.考察了其在大豆油酯交换反应制备生物柴油中的催化性能.结果表明,在相同反应条件下,与CaO/SBA-15和MgO/SBA-15相比,KOH/SBA-15在催化活性和孔扩散上都具有较大的优越性,催化制备生物柴油产率最高(83.56%).%SBA-15 was modified by introducing an active component by post-synthetic method for preparing a solid base catalyst KOH/SBA-15. Characterization was carried out by XRD,BET,TEM and CO2-TDP to understand the nature. KOH/SBA-15 catalytic performance on transesterification to produce biodiesel from soybean oil was studied. In the same reaction conditions, compared to CaO/SBA-15 and MgO/SBA-15,(15%)KOH/SBA-15 showed the highest yield of biodiesel,due to its favorable superiority on catalytic activity and pore diffusion.

  17. Catalytic Decoupling of Quantum Information

    DEFF Research Database (Denmark)

    Majenz, Christian; Berta, Mario; Dupuis, Frédéric

    2017-01-01

    The decoupling technique is a fundamental tool in quantum information theory with applications ranging from quantum thermodynamics to quantum many body physics to the study of black hole radiation. In this work we introduce the notion of catalytic decoupling, that is, decoupling in the presence...... of an uncorrelated ancilla system. This removes a restriction on the standard notion of decoupling, which becomes important for structureless resources, and yields a tight characterization in terms of the max-mutual information. Catalytic decoupling naturally unifies various tasks like the erasure of correlations...... and quantum state merging, and leads to a resource theory of decoupling....

  18. Catalytically highly active top gold atom on palladium nanocluster.

    Science.gov (United States)

    Zhang, Haijun; Watanabe, Tatsuya; Okumura, Mitsutaka; Haruta, Masatake; Toshima, Naoki

    2011-10-23

    Catalysis using gold is emerging as an important field of research in connection with 'green' chemistry. Several hypotheses have been presented to explain the markedly high activities of Au catalysts. So far, the origin of the catalytic activities of supported Au catalysts can be assigned to the perimeter interfaces between Au nanoclusters and the support. However, the genesis of the catalytic activities of colloidal Au-based bimetallic nanoclusters is unclear. Moreover, it is still a challenge to synthesize Au-based colloidal catalysts with high activity. Here we now present the 'crown-jewel' concept (Supplementary Fig. S1) for preparation of catalytically highly Au-based colloidal catalysts. Au-Pd colloidal catalysts containing an abundance of top (vertex or corner) Au atoms were synthesized according to the strategy on a large scale. Our results indicate that the genesis of the high activity of the catalysts could be ascribed to the presence of negatively charged top Au atoms.

  19. Studies on the antibacterial and catalytic activity of Schiff base mono-and di-nuclear complexes%Schiff碱单核与双核配合物的抗菌及催化活性研究

    Institute of Scientific and Technical Information of China (English)

    费宝丽; 燕庆玲; 李雯; 王大捷; 邵奎占; 苏忠民; 孙为银

    2011-01-01

    Two copper(Ⅱ) complexes [Cu2 (L)2 (CH3OH)] (dinuclear) (1) and [Cu(HL)2](mononuclear) ( 2 ) ( H2L = salicylidene-2-ethanolamine ) were synthesized and structurally characterized by elemental analysis and single-crystal X-ray diffraction. The Schiff base ligand and its complexes were tested in vitro to evaluate their antibacterial activities. The primary biological activity experiments showed that all products exhibited better activities against Gram-positive bacteria and the complex 1 was more active than free ligand and complex 2 against the same bacteria. Catalytic activities of the complexes for decomposition of H2O2 solution were investigated at various conditions. The effects of concentration of hydrogen peroxide, catalyst dosage, and basicity-acidity of the solution on the reaction were also investigated. The results indicated that,in basic solution, 0. 008 g of complex 1 had the best catalytic ability for the decomposition of 15 mL 15% hydrogen peroxide,and the catalytic activity of complex 1 was significantly higher than that of complex 2 and the corresponding metal salts. The antibacterial activity and catalytic results proved that, compared with complex 2, complex 1 is a better candidate to be antibacterial agent and catalyst for the reason of synergistic effect between metal ions.%合成了双核[Cu(HL)(CH3OH)](1)和单核[Cu(HI)2](2)(H2L=水杨醛缩乙醇胺)2个Schiff碱铜配合物.采用元素分析和x射线单晶衍射对配合物的组成和结构进行了表征.采用琼脂扩散法测定了配体和配合物的抑菌活性,同时研究了不同条件下配合物对H2O2分解的催化性能.实验表明:目标化合物对革兰氏阳性菌具有较好的抑制作用,并且配合物1的抑菌活性优于配体和配合物2;在碱性条件下,0.008 g配合物1作为催化剂,对15 mL15%过氧化氢溶液的催化分解效果最佳,同时配合物1的催化活性明显高于配合物2和相应金属盐的催化活性.

  20. Catalytic Asymmetric Bromocyclization of Polyenes.

    Science.gov (United States)

    Samanta, Ramesh C; Yamamoto, Hisashi

    2017-02-01

    The first catalytic asymmetric bromonium ion-induced polyene cyclization has been achieved by using a chiral BINOL-derived thiophosphoramide catalyst and 1,3-dibromo-5,5-dimethylhydantoin as an electrophilic bromine source. Bromocyclization products are obtained in high yields, with good enantiomeric ratios and high diastereoselectivity, and are abundantly found as scaffolds in natural products.

  1. Cutoff lensing: predicting catalytic sites in enzymes

    Science.gov (United States)

    Aubailly, Simon; Piazza, Francesco

    2015-10-01

    Predicting function-related amino acids in proteins with unknown function or unknown allosteric binding sites in drug-targeted proteins is a task of paramount importance in molecular biomedicine. In this paper we introduce a simple, light and computationally inexpensive structure-based method to identify catalytic sites in enzymes. Our method, termed cutoff lensing, is a general procedure consisting in letting the cutoff used to build an elastic network model increase to large values. A validation of our method against a large database of annotated enzymes shows that optimal values of the cutoff exist such that three different structure-based indicators allow one to recover a maximum of the known catalytic sites. Interestingly, we find that the larger the structures the greater the predictive power afforded by our method. Possible ways to combine the three indicators into a single figure of merit and into a specific sequential analysis are suggested and discussed with reference to the classic case of HIV-protease. Our method could be used as a complement to other sequence- and/or structure-based methods to narrow the results of large-scale screenings.

  2. Catalytically and noncatalytically treated automobile exhaust: biological effects in rats

    Energy Technology Data Exchange (ETDEWEB)

    Cooper, G.P. (Univ. of Cincinnati); Lewkowski, J.P.; Hastings, L.; Malanchuk, M.

    1977-12-01

    Chronic exposure to catalytically treated or noncatalytically treated automobile exhaust significantly depressed the spontaneous locomotor activity (SLA) of rats. Exposure to H/sub 2/SO/sub 4/ alone or CO at comparable levels did not alter the SLA. Exposure to noncatalytically treated exhaust resulted in significant reductions in growth rate and food and water intake. However, these effects were not evident in the exposure to catalytically treated exhaust or in the control H/sub 2/SO/sub 4/ and CO exposures. Blood acid-base analyses indicated that exposure to either catalytically treated exhaust or H/sub 2/SO/sub 4/ elicits a metabolic alkalosis, while exposure to CO alone results in a metabolic acidosis. All acid-base parameters were within the normal range several weeks after the termination of exposure.

  3. Catalytic Conversion of Carbohydrates

    DEFF Research Database (Denmark)

    Osmundsen, Christian Mårup

    -oxygenates through thermal retro-aldol condensations. One compound, glycolaldehyde, could be prepared in yields of over 60% by this method; as this compound can potentially be used as a starting point for producing a wide range of chemicals, such as ethylene glycol or acetic acid, this process could prove...... to be an efficient initial conversion step in the utilization of biomass for chemicals production. The shift from an oil based chemical industry to one based on renewable resources is bound to happen sooner or later, however the environmental problems associated with the burning of fossil resources means......Modern civilization is dependent on oil to supply energy for power, heating and transportation and carbon for the production of the plethora of chemicals needed. Oil is however a limited resource and alternatives need to be identified before we freeze in the dark [1]. This thesis deals...

  4. Research progress on catalytic oxidation by Schiff base complexes supported on mesoporous molecular sieve%介孔分子筛固载希夫碱金属配合物催化氧化研究进展

    Institute of Scientific and Technical Information of China (English)

    董阳阳; 白金泉; 王乔乔

    2013-01-01

    Schiff base complexes immobilized on mesoporous molecular sieve with high activity can be easily prepared and repeatedly used. It is considered to be a heterogeneous catalyst with great application potential. This article reviews the recent progress in oxidation catalyzed by Schiff base complexes supported on mesoporous molecular sieve, including catalytic oxidation of olefin, alkane, alcohol, sulfur ether.%介孔分子筛固载希夫碱金属配合物具有易于制备,反应活性高,可重复使用等优点,被认为是一种极具应用潜力的多相催化剂.近年来介孔分子筛固载希夫碱金属配合物在催化氧化方面研究较多.综述了近几年介孔分子筛固载希夫碱金属配合物在催化氧化方面的研究进展,主要包括催化氧化烯烃、烷烃、醇以及硫醚.

  5. Carbonates-based noble metal-free lean NOx trap catalysts MOx-K2CO3/K2Ti8O17 (M = Ce, Fe, Cu, Co) with superior catalytic performance

    Science.gov (United States)

    Zhang, Yuxia; You, Rui; Liu, Dongsheng; Liu, Cheng; Li, Xingang; Tian, Ye; Jiang, Zheng; Zhang, Shuo; Huang, Yuying; Zha, Yuqing; Meng, Ming

    2015-12-01

    A series of base metal-based lean NOx trap (LNT) catalysts MOx-K2CO3/K2Ti8O17 (M = Ce, Fe, Cu, Co) were synthesized by successive impregnations and employed for the storage and reduction of NOx in the emissions of lean-burn engines at 350 °C. The XRD and XANES/EXAFS results reveal that the active phases in the corresponding catalysts exist as CeO2, Fe2O3, CuO and Co3O4, respectively. Among all the catalysts, CoOx-K2CO3/K2Ti8O17 exhibits the best performance, which cannot only trap the NOx quickly and completely at lean condition, giving the highest storage capacity (3.32 mmol/g) reported so far, but also reduce the NOx at rich condition, showing a NOx reduction percentage as high as 99.0%. Meanwhile, this catalyst displays an ultralow NOx to N2O selectivity (0.3%) during NOx reduction. The excellent performance of CoOx-K2CO3/K2Ti8O17 results from its largest amount of surface active oxygen species as revealed by XPS, O2-TPD and NO-TPD. HRTEM, FT-IR and CO2-TPD results illustrate that several kinds of K species such as sbnd OK groups, K2O, surface carbonates and bulk or bulk-like carbonates coexist in the catalysts. Based upon the in situ DRIFTS results, the participation of K2CO3 in NOx storage is confirmed, and the predominant NOx storage species is revealed as bidentate nitrites formed via multiple kinetic pathways. The low cost and high catalytic performance of the CoOx-based LNT catalyst make it most promising for the substitution of noble metal-based LNT catalysts.

  6. Catalytic Conversion of Biofuels

    DEFF Research Database (Denmark)

    Jørgensen, Betina

    oxidation of ethanol to form acetyl compounds. The steam reforming has been covered by a literature study of the research work done so far giving an introduction to the use of ethanol as a feedstock. The partial oxidation of ethanol has been studied experimentally using gold and vanadium based heterogeneous...... catalysts, and two different experimental methods, namely, a batch system and a continuous flow system. In the batch reaction the process was carried out in the liquid phase using a gold catalyst and atmospheric air as the oxidant. Experiments were conducted at moderate pressures and temperatures (90-200 °C...

  7. Catalytic aerobic oxidation of phenols to ortho-quinones with air-stable copper precatalysts.

    Science.gov (United States)

    Askari, M S; Rodríguez-Solano, L A; Proppe, A; McAllister, B; Lumb, J-P; Ottenwaelder, X

    2015-07-21

    A range of air-stable copper species was examined for catalytic activity in the catalytic aerobic transformation of phenols into ortho-quinones. Efficient catalysis was obtained with commercially available copper(II) acetate. The stability of all constituents before mixing makes for a practical process that advances previously reported copper(I)-based oxygenations.

  8. Evolution of prokaryotic subtilases: genome-wide analysis reveals novel subfamilies with different catalytic residues

    NARCIS (Netherlands)

    Siezen, R.J.; Renckens, B.; Boekhorst, J.

    2007-01-01

    Subtilisin-like serine proteases (subtilases) are a very diverse family of serine proteases with low sequence homology, often limited to regions surrounding the three catalytic residues. Starting with different Hidden Markov Models (HMM), based on sequence alignments around the catalytic residues of

  9. Effect of biomass ash in catalytic fast pyrolysis of pine wood

    NARCIS (Netherlands)

    Yildiz, G.; Ronsse, F.; Venderbosch, R.H.; Duren, van R.; Kersten, S.R.A.; Prins, W.

    2015-01-01

    Fast pyrolysis experiments of pine wood have been performed in a continuously operated mechanically stirred bed reactor at 500 °C. The effects of the pine wood ash were studied by comparing non-catalytic and catalytic experiments (using a ZSM-5 based catalyst) with their ash-added counterparts. To s

  10. Bifunctional Imidazolium-Based Ionic Liquid Decorated UiO-67 Type MOF for Selective CO2 Adsorption and Catalytic Property for CO2 Cycloaddition with Epoxides.

    Science.gov (United States)

    Ding, Luo-Gang; Yao, Bing-Jian; Jiang, Wei-Ling; Li, Jiang-Tao; Fu, Qi-Juan; Li, Yan-An; Liu, Zhen-Hua; Ma, Jian-Ping; Dong, Yu-Bin

    2017-02-20

    A bifunctional robust and highly porous imidazolium-based ionic liquid decorated UiO-67 type MOF (UiO-67-IL, 1) was successfully constructed via solvothermal assembly of the imidazolium-based ligand and Zr(IV) ions. It exhibits a highly selective adsorption for CO2 over CH4 and N2. Furthermore, 1 herein can be used as a highly active heterogeneous catalyst for CO2 cycloaddition with epoxides under atmospheric pressure with or without cocatalyst TBAB (n-Bu4NBr).

  11. Radiation/Catalytic Augmented Combustion.

    Science.gov (United States)

    1980-09-01

    NATIO& NAk H(fJI At tl TANUAHTOb 19 A ~omm.81-0287 LVL RADIATION/CATALYTIC AUGMENTED COMBUST ION MOSHE LAVID CORPORATE RESEARCH-TECHNOLOGY FEASIBILITY...refinements as necessary. i. Perform cannular combustor experiments to Investigate ignition and flame attachment in flowing, liquid -fuel, unpremixed...stabilizer, with a sintered metal disk on the downstream side through which hot gases or products of partial fuel oxidation can be passed. Experimental

  12. 润滑油对轮胎主要成分催化裂解行为的影响%Effects of lubricant base oil on catalytic cracking behaviors of tire rubbers

    Institute of Scientific and Technical Information of China (English)

    渠巍; 周茜

    2011-01-01

    Effects of lubricant base oil (LBO) on catalytic cracking behaviors of three main components in tire rubbers, including natural rubber(NR) ,polybutadiene rubber(BR) , styrene-butadiene rubber( SBR) over ZSM-S zeolite, were investigated. It is found that LBO obviously enhances the catalytic effects of ZSM-S for pyrolysis of polybutadiene rubber;the pyrolysis rate increases;liquid yields increase from 69.0% to 83.4% ,and residue yields decrease from 17. 0% to 3.2%. For SBR,LBO increases the pyrolysis rate and the contents of light hydrocarbons from 67. 5% to 92.0% ,and decreases the average carbon number of the liquid products from 10. 5 to 8. 9. For NR, LBO increases the quality of the pyrolysis oil:the content of light hydrocarbons in liquid products increases from 79. 8% to 97. 2% ,and the average carbon number of the liquid products decreases from 10.3 to 8. 3.%本文研究了润滑油对轮胎的重要组成原料:天然橡胶、聚丁二烯橡胶和丁苯橡胶催化裂解行为的影响.研究发现润滑油的加入明显增强了催化剂ZSM-5对聚丁二烯橡胶的催化裂解作用:液体收率从69.0%提高到83.4%,残渣收率从17.0%降至3.2%;润滑油的加入也提高了丁苯橡胶催化裂解的反应速率,液体产物中的轻油组分由67.5%增加至92.0%,平均碳原子数由10.5降至8.9;润滑油的加入同样提高了天然橡胶催化裂解液体产物品质:液体产物中的轻油组分由79.8%增加至97.2%,平均碳原子数由10.3降至8.3.

  13. 烟气脱硝选择性催化还原催化剂反应模拟研究%Mathematical Simulation of Flue Gas Denitration Based on Selective Catalytic Reduction Catalyst

    Institute of Scientific and Technical Information of China (English)

    沈伯雄; 赵宁; 刘亭

    2011-01-01

    以E-R机制为动力学基础,建立了选择性催化还原(selective catalytic reduction,SCR)催化剂单孔道一维数学模型,用于模拟SCR催化剂孔道内的反应进程.模型同时还考虑了氨氧化的副反应以及孔道内反应的热效应.经过模拟结果和实验结果对照,证明了模型的合理性.利用模型计算了孔道内的浓度和温度分布、不同运行参数对NO转化率的影响,及催化剂孔大小与孔形状对脱硝效率的影响.模拟计算结果表明,沿孔道方向反应物浓度逐渐降低,而温度略有提高;在反应温度为320~380℃、氨氮比为1.0~1.05和空速为3 200 h-1的运行条件下,单孔道SCR的NO转化率能达到65%以上;另外,通过对孔形状和孔大小的模拟计算发现,催化剂孔节距应设计小于10mm为宜,而催化剂选用蜂窝式较板式和波纹板式具有更高的NO转化率.%Based on Eley-Rideal kinetic mechanism, the one dimensional mathematical model for (selective catalytic reduction, SCR) catalyst was established, to simulate the selective catalytic reduction process in the catalyst channel. The side effect of ammonia oxidation and the thermal effect on the reaction in the channel were considered simultaneously in the modeling. The model was testified to be reliable by compared with the experimental data. By the model, the concentration and temperature distributions in the channel were calculated. The effects of different operation parameters, the pitch and the shape of catalyst channel on De-Nox efficiency were also studied. It was shown that the concentration of reactants decreased along the channel direction, but the temperature increased slightly. According to the calculated results, the SCR de-NO+ efficiency for the single channel can reach over 65%, for the operating condition of temperature 320-380℃, NH3/N0 feed ratio 1.0-1.05, and gas hourly space velocity 3 200h-1. Besides, the pitch of catalyst should be designed less than 10mm; the

  14. Chemically-Modified Cellulose Paper as a Microstructured Catalytic Reactor

    Directory of Open Access Journals (Sweden)

    Hirotaka Koga

    2015-01-01

    Full Text Available We discuss the successful use of chemically-modified cellulose paper as a microstructured catalytic reactor for the production of useful chemicals. The chemical modification of cellulose paper was achieved using a silane-coupling technique. Amine-modified paper was directly used as a base catalyst for the Knoevenagel condensation reaction. Methacrylate-modified paper was used for the immobilization of lipase and then in nonaqueous transesterification processes. These catalytic paper materials offer high reaction efficiencies and have excellent practical properties. We suggest that the paper-specific interconnected microstructure with pulp fiber networks provides fast mixing of the reactants and efficient transport of the reactants to the catalytically-active sites. This concept is expected to be a promising route to green and sustainable chemistry.

  15. Catalytic Polymer Multilayer Shell Motors for Separation of Organics.

    Science.gov (United States)

    Lin, Zhihua; Wu, Zhiguang; Lin, Xiankun; He, Qiang

    2016-01-26

    A catalytic polymer multilayer shell motor has been developed, which effects fast motion-based separation of charged organics in water. The shell motors are fabricated by sputtering platinum onto the exposed surface of silica templates embedded in Parafilm, followed by layer-by-layer assembly of polyelectrolyte multilayers to the templates. The catalytic shell motors display high bubble propulsion with speeds of up to 260 μm s(-1) (13 body lengths per second). Moreover, the polyelectrolyte multilayers assembled at high pH (pH>9.0) adsorb approximately 89% of dye molecules from water, owing to the electrostatic interaction between the positively charged polymers and the anionic dye molecules, and subsequently release them at neutral pH in a microfluidic device. The efficient propulsion coupled with the effective adsorption behavior of the catalytic shell motors in a microfluidic device results in accelerated separation of organics in water and thus holds considerable promise for water analysis.

  16. Thermodynamics of catalytic nanoparticle morphology

    Science.gov (United States)

    Zwolak, Michael; Sharma, Renu; Lin, Pin Ann

    Metallic nanoparticles are an important class of industrial catalysts. The variability of their properties and the environment in which they act, from their chemical nature & surface modification to their dispersion and support, allows their performance to be optimized for many chemical processes useful in, e.g., energy applications and other areas. Their large surface area to volume ratio, as well as varying sizes and faceting, in particular, makes them an efficient source for catalytically active sites. These characteristics of nanoparticles - i.e., their morphology - can often display intriguing behavior as a catalytic process progresses. We develop a thermodynamic model of nanoparticle morphology, one that captures the competition of surface energy with other interactions, to predict structural changes during catalytic processes. Comparing the model to environmental transmission electron microscope images of nickel nanoparticles during carbon nanotube (and other product) growth demonstrates that nickel deformation in response to the nanotube growth is due to a favorable interaction with carbon. Moreover, this deformation is halted due to insufficient volume of the particles. We will discuss the factors that influence morphology and also how the model can be used to extract interaction strengths from experimental observations.

  17. Catalytic polarographic currents of oxidizers

    Energy Technology Data Exchange (ETDEWEB)

    Zajtsev, P.M.; Zhdanov, S.I.; Nikolaeva, T.D. (Vsesoyuznyj Nauchno-Issledovatel' skij Inst. Khimicheskikh Reaktivov i Osobo Chistykh Veshchestv, Moscow (USSR))

    1982-06-01

    The state of theory and practice of an important direction in polarography, i.e. catalytic currents of oxidizers-substrates that have found a wide application in the development of highly sensitive methods of determination of a large number of substrates, catalysts and polarographically nonactive ligands, is considered. Transition and some non-transition elements serve as catalysts of reactions that cause catalytic polarographic currents of substrates. Catalytic activity of an inorganic catalyst increases with the increase in the number of its d-orbit. Complex formation in most cases leads to the increase of catalyst activity, however, sometimes a reverse phenomenon takes place. For many catalysts the maximum activity is observed at pH values close to pK value of their hydrolysis. The properties of oxidizers-substrates is revealed by H/sub 2/O/sub 2/, ClO/sub 3//sup -/, BrO/sub 3//sup -/, IO/sub 3//sup -/, ClO/sub 4//sup -/, IO/sub 4//sup -/, NO/sub 2//sup -/, NO/sub 3//sup -/, NH/sub 2/OH, V(5), V(4), S/sub 2/O/sub 8//sup 2 -/, H/sub 2/SO/sub 4/, H/sub 2/C/sub 2/O/sub 4/, COHCOOH, alkenes compounds, organic halogen , sulfur- and amine-containing compounds.

  18. One-Step Catalytic Synthesis of CuO/Cu2O in a Graphitized Porous C Matrix Derived from the Cu-Based Metal-Organic Framework for Li- and Na-Ion Batteries.

    Science.gov (United States)

    Kim, A-Young; Kim, Min Kyu; Cho, Keumnam; Woo, Jae-Young; Lee, Yongho; Han, Sung-Hwan; Byun, Dongjin; Choi, Wonchang; Lee, Joong Kee

    2016-08-03

    The hybrid composite electrode comprising CuO and Cu2O micronanoparticles in a highly graphitized porous C matrix (CuO/Cu2O-GPC) has a rational design and is a favorable approach to increasing the rate capability and reversible capacity of metal oxide negative materials for Li- and Na-ion batteries. CuO/Cu2O-GPC is synthesized through a Cu-based metal-organic framework via a one-step thermal transformation process. The electrochemical performances of the CuO/Cu2O-GPC negative electrode in Li- and Na-ion batteries are systematically studied and exhibit excellent capacities of 887.3 mAh g(-1) at 60 mA g(-1) after 200 cycles in a Li-ion battery and 302.9 mAh g(-1) at 50 mA g(-1) after 200 cycles in a Na-ion battery. The high electrochemical stability was obtained via the rational strategy, mainly owing to the synergy effect of the CuO and Cu2O micronanoparticles and highly graphitized porous C formed by catalytic graphitization of Cu nanoparticles. Owing to the simple one-step thermal transformation process and resulting high electrochemical performance, CuO/Cu2O-GPC is one of the prospective negative active materials for rechargeable Li- and Na-ion batteries.

  19. Biodiesel by catalytic reactive distillation powered by metal oxides

    NARCIS (Netherlands)

    Kiss, A.A.; Dimian, A.C.; Rothenberg, G.

    2008-01-01

    The properties and use of biodiesel as a renewable fuel as well as the problems associated with its current production processes are outlined. A novel sustainable esterification process based on catalytic reactive distillation is proposed. The pros and cons of manufacturing biodiesel via fatty acid

  20. Assessing the reliability of calculated catalytic ammonia synthesis rates

    DEFF Research Database (Denmark)

    Medford, Andrew James; Wellendorff, Jess; Vojvodic, Aleksandra

    2014-01-01

    We introduce a general method for estimating the uncertainty in calculated materials properties based on density functional theory calculations. We illustrate the approach for a calculation of the catalytic rate of ammonia synthesis over a range of transition-metal catalysts. The correlation...

  1. Direct catalytic cross-coupling of organolithium compounds

    NARCIS (Netherlands)

    Giannerini, Massimo; Fananas Mastral, Martin; Feringa, Ben L.

    2013-01-01

    Catalytic carbon-carbon bond formation based on cross-coupling reactions plays a central role in the production of natural products, pharmaceuticals, agrochemicals and organic materials. Coupling reactions of a variety of organometallic reagents and organic halides have changed the face of modern sy

  2. Synthesis and catalytic activity of Ln(III) complexes with an unsymmetrical Schiff base including multi()C = N-groups

    Institute of Scientific and Technical Information of China (English)

    姚克敏; 李宁; 沈联芳

    2003-01-01

    A synthetic method for a new unsymmetrical Schiff base and its Ln (III) complexes including multi C == N- groups is reported. The complexes are characterized by elemental analysis, IR spectra, 1H and 13C NMR, especially 2D-COSY1H, 1H NMR spectra. The general formula of the obtained complexes is [Ln3(TBLY)(NO3)3]@nH2O (Ln = La, n = 3; Ln = Nd, n = 5; Ln = Gd, Dy, Yb, Y, n = 7), whereTBLY = tetraglycol aldehyde-2,4-dihydroxy benzaldehyde bis-lysine Schiff base. In addition, the evidence for existence of C == CH-NH- group is supported bythe AM1 method. The complexes obtained may be used as a catalyst. Conversion rate of 80% with the viscosity-average molecular weight 220000 for the polymerization of methyl methacrylate (MMA) without addition of any cocatalyst has been obtained.

  3. System with potential dual modes of metal-ligand cooperation: highly catalytically active pyridine-based PNNH-Ru pincer complexes.

    Science.gov (United States)

    Fogler, Eran; Garg, Jai Anand; Hu, Peng; Leitus, Gregory; Shimon, Linda J W; Milstein, David

    2014-11-24

    Metal-ligand cooperation (MLC) plays an important role in catalysis. Systems reported so far are generally based on a single mode of MLC. We report here a system with potential for MLC by both amine-amide and aromatization-dearomatization ligand transformations, based on a new class of phosphino-pyridyl ruthenium pincer complexes, bearing sec-amine coordination. These pincer complexes are effective catalysts under unprecedented mild conditions for acceptorless dehydrogenative coupling of alcohols to esters at 35 °C and hydrogenation of esters at room temperature and 5 atm H2. The likely actual catalyst, a novel, crystallographically characterized monoanionic de-aromatized enamido-Ru(II) complex, was obtained by deprotonation of both the N-H and the methylene proton of the N-arm of the pincer ligand.

  4. Carbogenic molecular sieves for reaction and separation by design: A novel approach to shape selective super base, super acid and catalytic membranes. Final report

    Energy Technology Data Exchange (ETDEWEB)

    Foley, Henry C.

    2002-03-18

    This report details the findings of three years of research plus one year of a no-cost extension. Primary results are the work with supported nanoporous carbon membranes for separation and reaction as well as with cesium-nanoporous carbon catalysts. The work resulted in 17 plus 2 papers (2 are in progress) and partial or full support for five Ph.D. students. Two patents were filed based on this research.

  5. The Influence of Base Metal (M Oxidation State in Au-M-O/TiO2 Systems on Their Catalytic Activity in Carbon Monoxide Oxidation

    Directory of Open Access Journals (Sweden)

    Katarzyna Samson

    2011-12-01

    Full Text Available Base metal promoted gold/titania catalysts were synthesized, characterized and tested in CO oxidation reaction. Catalysts containing dopant metals in higher oxidation states exhibited higher activity than catalysts containing dopants in reduced states. The activity of fresh catalysts promoted by Cu, Fe and Ni was similar to the unpromoted one, but treatment in reducing and oxidizing atmospheres revealed the supremacy of the copper promoted catalyst. The sequential deposition method proved to be better than the co-deposition—precipitation method. An attempt to explain these differences using XPS, FTIR and H2 TPR was performed.

  6. EFFECTS OF SOLVENT, BASE, AND TEMPERATURE IN THE OPTIMISATION OF A NEW CATALYTIC SYSTEM FOR SONOGASHIRA CROSS-COUPLING USING NCP PINCER PALLADACYCLE

    Directory of Open Access Journals (Sweden)

    Diego S. Rosa

    2015-05-01

    Full Text Available The optimisation of a new catalyst system using NCP pincer palladacycle 1 was investigated using the experimental design technique. NCP pincer palladacycle 1 was previously investigated in Suzuki-Miyaura and Heck-Mizoroki cross-couplings and found to be a highly efficient catalyst precursor. In this study, the effects of the type of base (K3PO4 or DABCO, solvent (DMF or dioxane and reaction temperature (130 or 150 ºC in the second step on the reactional yield in Sonogashira cross-coupling were assessed using the two-factor design. The results showed that temperature is statistically significant in relation to the reaction yield.

  7. A catalytically and genetically optimized beta-lactamase-matrix based assay for sensitive, specific, and higher throughput analysis of native henipavirus entry characteristics

    OpenAIRE

    2009-01-01

    Abstract Nipah virus (NiV) and Hendra virus (HeV) are the only paramyxoviruses requiring Biosafety Level 4 (BSL-4) containment. Thus, study of henipavirus entry at less than BSL-4 conditions necessitates the use of cell-cell fusion or pseudotyped reporter virus assays. Yet, these surrogate assays may not fully emulate the biological properties unique to the virus being studied. Thus, we developed a henipaviral entry assay based on a β-lactamase-Nipah Matrix (βla-M) fusion protein...

  8. Research Progress of Ceria-Based Catalysts in the Selective Catalytic Reduction of NOx by NH3%铈基催化剂用于NH3选择性催化还原NOx的研究进展

    Institute of Scientific and Technical Information of China (English)

    姚小江; 贡营涛; 李红丽; 杨复沫

    2015-01-01

    源自固定源(如燃煤电厂烟气)和移动源(如机动车尾气)排放的氮氧化物(NOx)造成了严重的大气污染,对其进行减排控制已迫在眉睫。研究表明,氨选择性催化还原(NH3-SCR)技术是消除NOx的最有效手段之一。铈基催化剂因其良好的氧化还原性能、适当的表面酸性、较高的储/释氧容量以及丰富的资源储备而被广泛用于NH3-SCR反应。探讨铈基组分在该反应中发挥的具体作用,有助于了解相关催化过程的本质,为现有催化剂的优化和新型催化剂的设计提供科学参考。基于CeO2在NH3-SCR催化剂中扮演的不同角色,本文从CeO2作为载体、铈基复合氧化物、表面负载组分(助剂和活性组分)以及特殊结构的铈基催化剂等方面系统地介绍了近年来铈基催化剂在NH3-SCR反应中的最新研究进展,并对该领域未来可能的发展方向进行了展望。%Nitrogen oxides (NOx), which are emitted from stationary sources (such as coal-fired power plant flue gases) and mobile sources (such as motor vehicle exhausts), cause serious atmospheric pol ution. As a result, it is very important to control the emissions of NOx. Some studies have suggested that NH3-selective catalytic reduction (NH3-SCR) of NOx is one of the best techniques for this purpose. Ceria-based catalysts are widely used in the NH3-SCR reaction because of their good redox ability, suitable surface acidity, high oxygen storage or release capacity, and rich resource reserves. Investigating the role of ceria component in this reaction is important to understand the nature of the related catalytic process, and provides a valuable scientific reference for the optimization of existing catalysts and the design of novel catalysts. Based on the different roles of ceria in NH3-SCR catalysts, we have performed a systematic review of the latest research progress of ceria-based catalysts in the NH3-SCR reaction for the fol owing aspects:CeO2

  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. Synthesis and catalytic activity of novel heteronuclear Ln(Ⅲ)-Cu(Ⅱ) complexes with noncyclic polyether-amino acid Schiff base

    Institute of Scientific and Technical Information of China (English)

    姚克敏; 李宁; 黄巧虹; 沈联芳; 袁汉珍

    1999-01-01

    A series of novel heteronuclear Ln(Ⅲ)-Cu(Ⅱ) complexes with noncyclic polyether-amino acid Schiff base were synthesized. The general formula is [LnCu2(H2TALY)(NO3)5](NO3)2’ nH2O(Ln=La, Nd, Sm, Gd, n= 4; Ln=Yb, Y, n=3), where H2TALY = tetraglycol aldehyde bis-lysine Schiff base. It is the first time to report the synthetic method for this new Cu(Ⅱ) complexes and Ln(Ⅲ)-Cu(Ⅱ) heteronuclear complexes. The complexes were characterized by elemental analysis, IR spectra, TG-DTA, magnetic susceptibility, and especially by a 500 MHz NMR spectrometer for 2D-COSY NMR. Coordination mechanism and structures of complexes have been suggested as well. Of particular interest is the potential that the novel complexes obtained may be used as a catalyst, which prompted us to investigate them. It shows 100% conversion with the viscosity-average molecular weight 120 000 for the polymerization of methyl methacrylate (MMA) without addition of any cocatalyst. Furthermore, the complexes with such aliphatic Schiff bas

  11. SYNTHESIS AND CATALYTIC PROPERTY OF POLYSTYRENE SUPPORTED GLUTAMIC ACID SCHIFF BASE COMPLEX OF Mn(Ⅱ)IN AEROBIC OXIDATION OF CYCLOHEXENE

    Institute of Scientific and Technical Information of China (English)

    CHEN Songtao; ZHAO Ganqing; LU Xiaoqing; XIE Jimin

    2007-01-01

    The polystyrene supported glutamic acid Schiff base complex of Mn (Ⅱ) (PS-Sal-Glue-Mn) was prepared with chloromethylated styrene polymer beads,2,4-dihydroxybenzaldehyde, L-glutamic acid and manganese (Ⅱ) acetate tetrahyrate. The polymeric ligand and the complex were characterized by FT-IR, small area X-ray photoelectron spectroscopy (XPS) and ICP-AES. In the presence of the manganese complex, cyclohexene (1) was effectively oxidized by molecular oxygen without reductant. The major products of the reaction were 2-cyclohexen-1-ol (2), 2-cyclohexen-1-one (3) and 2-cyclohexen-1- hydroperoxide (4), which was different with typical oxidation of cyclohexene. The influence of reaction temperature and additive for oxidation had been studied. The selectivity of 2-cyclohexen-1-hydroperoxide varied with reaction time and different additives. The mechanism of cyclohexene oxidation had also been discussed.

  12. Catalytic performance for CO{sub 2} conversion to methanol of gallium-promoted copper-based catalysts. Influence of metallic precursors

    Energy Technology Data Exchange (ETDEWEB)

    Toyir, Jamil; Ramirez de la Piscina, Pilar; Homs, Narcis [Departament de Quimica Inorganica, Facultat de Quimica, Universitat de Barcelona, Marti i Franques 1-11, 08028 Barcelona (Spain); Fierro, Jose Luis G. [Instituto de Catalisis y Petroleoquimica, C.S.I.C., Cantoblanco, 28049 Madrid (Spain)

    2001-11-28

    This study reports new gallium-promoted copper-based catalysts prepared by co-impregnation of methoxide-acetylacetonate (acac) precursors from methanolic solutions onto silica and zinc oxide supports. Catalyst performance in the CO{sub 2} hydrogenation to methanol was investigated at 2MPa and temperatures between 523 and 543K. A high activity and selectivity for ZnO-supported catalysts was found, which also showed a high stability in terms of both activity and selectivity. The maximum value for the activity was 378gMeOH/kgcath at 543K, with a selectivity of 88% towards methanol production. The high performance of these materials in the CO{sub 2} hydrogenation is related to the presence of Ga{sub 2}O{sub 3} promoter and highly dispersed Cu{sup +} species on the surface, determined by XPS and Auger on used catalysts.

  13. MWCNT-Based Ag2S-TiO2 Nanocomposites Photocatalyst: Ultrasound-Assisted Synthesis, Characterization, and Enhanced Catalytic Efficiency

    Directory of Open Access Journals (Sweden)

    Lei Zhu

    2012-01-01

    Full Text Available Multiwalled carbon nanotube based nanoscale Ag2S and TiO2 composites have successfully synthesized via a facile ultrasound-assisted method. The nanocomposites were characterized by Fourier transform infrared (FT-IR spectroscopy, UV-vis absorption spectra, BET surface area measurements, X-ray diffraction (XRD, and transmission electron microscopy (TEM. The Ag2S-TiO2/CNT nanocomposites exhibited much higher photocatalytic activity than pure TiO2 for the degradation of Rhodamine B (Rh.B under UV and visible light. The improved photocatalytic activities may be attributed to increased adsorbability of Rh.B molecules and increased charge transfer rate in the presence of a one-dimensional MWCNT network.

  14. SYNTHESIS AND CATALYTIC PROPERTY OF POLYSTYRENE SUPPORTED GLUTAMIC ACID SCHIFF BASE COMPLEX OF Mn(Ⅱ) IN AEROBIC OXIDATION OF CYCLOHEXENE

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    The polystyrene supported glutamic acid Schiff base complex of Mn (Ⅱ) (PS-Sal-Glue-Mn) was prepared with chloromethylated styrene polymer beads, 2,4-dihydroxybenzaldehyde, L-glutamic acid and manganese (Ⅱ) acetate tetrahyrate. The polymeric ligand and the complex were characterized by FT-IR, small area X-ray photoelectron spectroscopy (XPS) and ICP-AES. In the presence of the manganese complex, cyclohexene (1) was effectively oxidized by molecular oxygen without reductant. The major products of the reaction were 2-cyclohexen-1-ol (2), 2-cyclohexen-1-one (3) and 2-cyclohexen-1- hydroperoxide (4), which was different with typical oxidation of cyclohexene. The influence of reaction temperature and additive for oxidation had been studied. The selectivity of 2-cyclohexen-1-hydroperoxide varied with reaction time and different additives. The mechanism of cyclohexene oxidation had also been discussed.

  15. Bipyridine- and phenanthroline-based metal-organic frameworks for highly efficient and tandem catalytic organic transformations via directed C-H activation

    Energy Technology Data Exchange (ETDEWEB)

    Manna, Kuntal [Univ. of Chicago, Chicago, IL (United States); Zhang, Teng [Univ. of Chicago, Chicago, IL (United States); Greene, Francis X. [Univ. of Chicago, Chicago, IL (United States); Lin, Wenbin [Univ. of Chicago, Chicago, IL (United States)

    2015-02-16

    We report here the synthesis of a series of robust and porous bipyridyl- and phenanthryl-based metal–organic frameworks (MOFs) of UiO topology (BPV-MOF, mBPV-MOF, and mPT-MOF) and their postsynthetic metalation to afford highly active single-site solid catalysts. While BPV-MOF was constructed from only bipyridyl-functionalized dicarboxylate linker, both mBPV- and mPT-MOF were built with a mixture of bipyridyl- or phenanthryl-functionalized and unfunctionalized dicarboxylate linkers. The postsynthetic metalation of these MOFs with [Ir(COD)(OMe)]2 provided Ir-functionalized MOFs (BPV-MOF-Ir, mBPV-MOF-Ir, and mPT-MOF-Ir), which are highly active catalysts for tandem hydrosilylation of aryl ketones and aldehydes followed by dehydrogenative ortho-silylation of benzylicsilyl ethers as well as C–H borylation of arenes using B₂pin₂. Both mBPV-MOF-Ir and mPT-MOF-Ir catalysts displayed superior activities compared to BPV-MOF-Ir due to the presence of larger open channels in the mixed-linker MOFs. Impressively, mBPV-MOF-Ir exhibited high TONs of up to 17000 for C–H borylation reactions and was recycled more than 15 times. The mPT-MOF-Ir system is also active in catalyzing tandem dehydrosilylation/dehydrogenative cyclization of N-methylbenzyl amines to azasilolanes in the absence of a hydrogen acceptor. Importantly, MOF-Ir catalysts are significantly more active (up to 95 times) and stable than their homogeneous counterparts for all three reactions, strongly supporting the beneficial effects of active site isolation within MOFs. This work illustrates the ability to increase MOF open channel sizes by using the mixed linker approach and shows the enormous potential of developing highly active and robust single-site solid catalysts based on MOFs containing nitrogen-donor ligands for important organic transformations.

  16. Synthesis and reactivity of iron complexes with a new pyrazine-based pincer ligand, and application in catalytic low-pressure hydrogenation of carbon dioxide.

    Science.gov (United States)

    Rivada-Wheelaghan, Orestes; Dauth, Alexander; Leitus, Gregory; Diskin-Posner, Yael; Milstein, David

    2015-05-04

    A novel pincer ligand based on the pyrazine backbone (PNzP) has been synthesized, (2,6-bis(di(tert-butyl)phosphinomethyl)pyrazine), tBu-PNzP. It reacts with FeBr2 to yield [Fe(Br)2(tBu-PNzP)], 1. Treatment of 1 with NaBH4 in MeCN/MeOH gives the hydride complex [Fe(H)(MeCN)2(tBu-PNzP)][X] (X = Br, BH4), 2·X. Counterion exchange and exposure to CO atmosphere yields the complex cis-[Fe(H)(CO)(MeCN)(tBu-PNzP)][BPh4] 4·BPh4, which upon addition of Bu4NCl forms [Fe(H)(Cl)(CO)(tBu-PNzP)] 5. Complex 5, under basic conditions, catalyzes the hydrogenation of CO2 to formate salts at low H2 pressure. Treatment of complex 5 with a base leads to aggregates, presumably of dearomatized species B, stabilized by bridging to another metal center by coordination of the nitrogen at the backbone of the pyrazine pincer ligand. Upon dissolution of compound B in EtOH the crystallographically characterized complex 7 is formed, comprised of six iron units forming a 6-membered ring. The dearomatized species can activate CO2 and H2 by metal-ligand cooperation (MLC), leading to complex 8, trans-[Fe(PNzPtBu-COO)(H)(CO)], and complex 9, trans-[Fe(H)2(CO)(tBu-PNzP)], respectively. Our results point at a very likely mechanism for CO2 hydrogenation involving MLC.

  17. Modification of HZSM- 5 Zeolite by Hydrochloric Acid and Catalytic Performance of Mo - based Catalyst for Methane Dehydroaromatization Reaction%盐酸改性HZSM-5及Mo-基催化剂的MDA反应活性

    Institute of Scientific and Technical Information of China (English)

    王红霞; 赵婷婷

    2012-01-01

    采用盐酸溶液在303K对HZSM-5分子筛进行预处理,并以处理后的分子筛制备相应的Mo-基催化剂.分子筛和催化剂采用XRD和NH3-TPD等手段进行表征,利用甲烷无氧芳构化(MDA)反应评价Mo-基催化剂的催化活性.结果表明,指定实验条件下的盐酸处理在一定程度上降低了分子筛的结晶度,降低了分子筛上的B酸量,改性后的Mo-基催化剂在MDA反应中表现很好的稳定性.%The pretreatment with HC1 solution at 303 K was applied to modify HZSM -5 zeolite, and the Mobased catalysts were prepared by using the modified HZSM -5 zeolite as support and tested for catalytic performance of methane dehydroaromatization reaction. The modified Mo - based catalysts show a higher stability than that of Mo/HZSM - 5 catalyst prepared with unmodified with HZSM - 5 zeolite. The effect of acid treatment on the structure and acidity of HZSM - 5 zeolite and Mo - based catalysts were studied by XRD and NH3 - TPD methods. The results show that the acid treatment to HZSM - 5 at given experimental conditions led to a decrease in the crystallinity of HZSM -5 zeolite and the number of the Brnsted acid sites to a certain degree.

  18. Label-free and ratiometric detection of nuclei acids based on graphene quantum dots utilizing cascade amplification by nicking endonuclease and catalytic G-quadruplex DNAzyme.

    Science.gov (United States)

    Wang, Guang-Li; Fang, Xin; Wu, Xiu-Ming; Hu, Xue-Lian; Li, Zai-Jun

    2016-07-15

    Herein, we report a ratiometric fluorescence assay based on graphene quantum dots (GQDs) for the ultrasensitive DNA detection by coupling the nicking endonuclease assisted target recycling and the G-quadruplex/hemin DNAzyme biocatalysis for cascade signal amplifications. With o-phenylenediamine acted as the substrate of G-quadruplex/hemin DNAzyme, whose oxidization product (that is, 2,3-diaminophenazine, DAP) quenched the fluorescence intensity of GQDs (at 460nm) obviously, accompanied with the emergence of a new emission of DAP (at 564nm). The ratiometric signal variations at the emission wavelengths of 564 and 460nm (I564/I460) were utilized for label-free, sensitive, and selective detection of target DNA. Utilizing the nicking endonuclease assisted target recycling and the G-quadruplex/hemin DNAzyme biocatalysis for amplified cascade generation of DAP, the proposed bioassay exhibited high sensitivity toward target DNA with a detection limit of 30fM. The method also had additional advantages such as facile preparation and easy operation.

  19. Naked-eye sensitive detection of alkaline phosphatase (ALP) and pyrophosphate (PPi) based on a horseradish peroxidase catalytic colorimetric system with Cu(ii).

    Science.gov (United States)

    Shi, Dongmin; Sun, Yue; Lin, Lin; Shi, Chunjun; Wang, Guangfeng; Zhang, Xiaojun

    2016-10-07

    In this paper, a novel colorimetric method for the detection of alkaline phosphatase (ALP) and pyrophosphate (PPi) was designed based on a Cu(2+)-horseradish peroxidase (HRP)-3,3',5,5'-tetra-methylbenzidine (TMB)-H2O2 system. In the presence of ALP, l-ascorbic acid-2-phosphate (AAP) could be hydrolyzed to ascorbic acid which could reduce Cu(2+) to Cu(+) to inhibit the enzymatic activity of HRP in the colorimetric system. The change in absorbance was found to be proportional to the ALP concentration with a linear detection range and a limit of detection of 5.4 mU mL(-1). In the presence of PPi, because Cu(2+) was chelated by PPi, the conversion of Cu(ii) by AA was effectively inhibited. The color of the HRP-TMB-H2O2 system with Cu(2+) showed blue. The HRP-TMB-H2O2 system with the Cu(2+) colorimetric system could also detect PPi with a satisfying result. In summary, this method possesses sensitivity, reproducibility, and cost-effectiveness without labelling and separation and the use of a colorimetric method is more in line with the requirements of on-site detection and green chemistry.

  20. 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

  1. Molecular catalytic coal liquid conversion

    Energy Technology Data Exchange (ETDEWEB)

    Stock, L.M.; Yang, Shiyong [Univ. of Chicago, IL (United States)

    1995-12-31

    This research, which is relevant to the development of new catalytic systems for the improvement of the quality of coal liquids by the addition of dihydrogen, is divided into two tasks. Task 1 centers on the activation of dihydrogen by molecular basic reagents such as hydroxide ion to convert it into a reactive adduct (OH{center_dot}H{sub 2}){sup {minus}} that can reduce organic molecules. Such species should be robust withstanding severe conditions and chemical poisons. Task 2 is focused on an entirely different approach that exploits molecular catalysts, derived from organometallic compounds that are capable of reducing monocyclic aromatic compounds under very mild conditions. Accomplishments and conclusions are discussed.

  2. Structured materials for catalytic and sensing applications

    Science.gov (United States)

    Hokenek, Selma

    been synthesized and characterized to establish the effects of nanoparticle size on catalytic activity in methanol decomposition. The physicochemical properties of the synthesized palladium-nickel nanoparticles will be discussed, as a function of the synthesis parameters. The optical characteristics of the Ag and Pd nanoparticles will be determined, with a view toward tuning the response of the nanoparticles for incorporation in sensors. Analysis of the monometallic palladium particles revealed a dependence of syngas production on nanoparticle size. The peak and steady state TOFs increased roughly linearly with the average nanoparticle diameter. The amount of coke deposited on the particle surfaces was found to be independent on the size of the nanoparticles. Shape control of the nickel-palladium nanoparticles with a high selectivity for (100) and (110) facets (≤ 80%) has been demonstrated. The resulting alloy nanoparticles were found to have homogeneous composition throughout their volume and maintain FCC crystal structure. Substitution of Ni atoms in the Pd lattice at a 1:3 molar ratio was found to induce lattice strains of ~1%. The Ag nanocubes synthesized exhibited behavior very similar to literature values, when taken on their own, exhibiting a pair of distinct absorbance peaks at 350 nm and 455 nm. In physical mixtures with the Pd nanoparticles synthesized, their behavior showed that the peak position of the Ag nanocubes' absorbance in UV-Vis could be tuned based on the relative proportions of the Ag and Pd nanoparticles present in the suspension analysed. The Ag polyhedra synthesized for comparison showed a broad doublet peak throughout the majority of the visible range before testing as a component in a physical mixture with the Pd nanoparticles. The addition of Pd nanoparticles to form a physical mixture resulted in some damping of the doublet peak observed as well as a corresponding shift in the baseline absorbance proportional to the amount of Pd added to

  3. 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)

  4. Some Aspects of the Catalytic Organic Synthesis

    Institute of Scientific and Technical Information of China (English)

    Anil; K.Saikia

    2007-01-01

    1 Results Catalytic reactions are gaining importance due to its low cost, operational simplicity, high efficiency and selectivity. It is also getting much attention in green synthesis. Many useful organic reactions, including the acylation of alcohols and aldehydes, carbon-carbon, carbon-nitrogen, carbon-sulfur bond forming and oxidation reactions are carried out by catalyst. We are exploring the catalytic acylation of alcohols and aldehydes in a simple and efficient manner. Catalytic activation of unr...

  5. Catalytic microrotor driven by geometrical asymmetry

    Science.gov (United States)

    Yang, Mingcheng; Ripoll, Marisol; Chen, Ke

    2015-02-01

    An asymmetric gear with homogeneous surface properties is, here, presented as a prototype to fabricate catalytic microrotors. The driving torque arises from the diffusiophoretic effect induced by the concentration gradients generated by catalytic chemical reactions at the gear surface. This torque produces a spontaneous and unidirectional rotation of the asymmetric gear. By means of mesoscopic simulations, we prove and characterize this scenario. The gear rotational velocity is determined by the gear-solvent interactions, the gear geometry, the solvent viscosity, and the catalytic reaction ratio. Our work presents a simple way to design self-propelled microrotors, alternative to existing catalytic bi-component, or thermophoretic ones.

  6. Nanostructured Catalytic Reactors for Air Purification Project

    Data.gov (United States)

    National Aeronautics and Space Administration — This SBIR Phase I project proposes the development of lightweight compact nanostructured catalytic reactors for air purification from toxic gaseous organic...

  7. Nanostructured Catalytic Reactors for Air Purification Project

    Data.gov (United States)

    National Aeronautics and Space Administration — This SBIR Phase II project proposes the development of lightweight compact nanostructured catalytic reactors for air purification from toxic gaseous organic...

  8. Stoichiometric and Catalytic Synthesis of Alkynylphosphines

    Directory of Open Access Journals (Sweden)

    Annie-Claude Gaumont

    2012-12-01

    Full Text Available Alkynylphosphines or their borane complexes are available either through C–P bond forming reactions or through modification of the phosphorus or the alkynyl function of various alkynyl phosphorus derivatives. The latter strategy, and in particular the one involving phosphoryl reduction by alanes or silanes, is the method of choice for preparing primary and secondary alkynylphosphines, while the former strategy is usually employed for the synthesis of tertiary alkynylphosphines or their borane complexes. The classical C–P bond forming methods rely on the reaction between halophosphines or their borane complexes with terminal acetylenes in the presence of a stoichiometric amount of organometallic bases, which precludes the access to alkynylphosphines bearing sensitive functional groups. In less than a decade, efficient catalytic procedures, mostly involving copper complexes and either an electrophilic or a nucleophilic phosphorus reagent, have emerged. By proceeding under mild conditions, these new methods have allowed a significant broadening of the substituent scope and structure complexity.

  9. Soluble organic nanotubes for catalytic systems

    Science.gov (United States)

    Xiong, Linfeng; Yang, Kunran; Zhang, Hui; Liao, Xiaojuan; Huang, Kun

    2016-03-01

    In this paper, we report a novel method for constructing a soluble organic nanotube supported catalyst system based on single-molecule templating of core-shell bottlebrush copolymers. Various organic or metal catalysts, such as sodium prop-2-yne-1-sulfonate (SPS), 1-(2-(prop-2-yn-1-yloxy)ethyl)-1H-imidazole (PEI) and Pd(OAc)2 were anchored onto the tube walls to functionalize the organic nanotubes via copper-catalyzed azide-alkyne cycloaddition (CuAAC) reaction. Depending on the ‘confined effect’ and the accessible cavity microenvironments of tubular structures, the organic nanotube catalysts showed high catalytic efficiency and site-isolation features. We believe that the soluble organic nanotubes will be very useful for the development of high performance catalyst systems due to their high stability of support, facile functionalization and attractive textural properties.

  10. Study on catalytic oxidation of planar binuclear copper phthalocyanine on 2-mercaptoethanol

    Institute of Scientific and Technical Information of China (English)

    CHEN Wenxing; WEI Lili; WANG Jinqian; YAO Yuyuan; L(U) Shenshui; CHEN Shiliang

    2006-01-01

    Mononuclear copper phthalocyanine (CuPc) and binuclear copper phthalocyanine (Cu2Pc2) were synthesized by the phenylanhydride-urea route, and their catalytic oxidation activity on 2-mercaptoethanol was studied. Based on the experimental results, a catalytic mechanism of Cu2Pc2 on 2-mercaptoethanol has been proposed. Furthermore, the effects of pH, Cu2Pc2 concentration, and temperature on the catalytic oxidation activity were evaluated. The results showed that CuPc has no catalytic activity, while Cu2Pc2 has high catalytic oxidation activity towards 2-mercaptoethanol with the optimal activity at pH 11. The reaction can further be enhanced by increasing Cu2Pc2 concentration and temperature, due to its endothermic characteristics.

  11. Experimental Investigation of Flow Resistance in a Coal Mine Ventilation Air Methane Preheated Catalytic Oxidation Reactor

    Directory of Open Access Journals (Sweden)

    Bin Zheng

    2015-01-01

    Full Text Available This paper reports the results of experimental investigation of flow resistance in a coal mine ventilation air methane preheated catalytic oxidation reactor. The experimental system was installed at the Energy Research Institute of Shandong University of Technology. The system has been used to investigate the effects of flow rate (200 Nm3/h to 1000 Nm3/h and catalytic oxidation bed average temperature (20°C to 560°C within the preheated catalytic oxidation reactor. The pressure drop and resistance proportion of catalytic oxidation bed, the heat exchanger preheating section, and the heat exchanger flue gas section were measured. In addition, based on a large number of experimental data, the empirical equations of flow resistance are obtained by the least square method. It can also be used in deriving much needed data for preheated catalytic oxidation designs when employed in industry.

  12. Catalytically active nanomaterials: a promising candidate for artificial enzymes.

    Science.gov (United States)

    Lin, Youhui; Ren, Jinsong; Qu, Xiaogang

    2014-04-15

    Natural enzymes, exquisite biocatalysts mediating every biological process in living organisms, are able to accelerate the rate of chemical reactions up to 10(19) times for specific substrates and reactions. However, the practical application of enzymes is often hampered by their intrinsic drawbacks, such as low operational stability, sensitivity of catalytic activity to environmental conditions, and high costs in preparation and purification. Therefore, the discovery and development of artificial enzymes is highly desired. Recently, the merging of nanotechnology with biology has ignited extensive research efforts for designing functional nanomaterials that exhibit various properties intrinsic to enzymes. As a promising candidate for artificial enzymes, catalytically active nanomaterials (nanozymes) show several advantages over natural enzymes, such as controlled synthesis in low cost, tunability in catalytic activities, as well as high stability against stringent conditions. In this Account, we focus on our recent progress in exploring and constructing such nanoparticulate artificial enzymes, including graphene oxide, graphene-hemin nanocomposites, carbon nanotubes, carbon nanodots, mesoporous silica-encapsulated gold nanoparticles, gold nanoclusters, and nanoceria. According to their structural characteristics, these enzyme mimics are categorized into three classes: carbon-, metal-, and metal-oxide-based nanomaterials. We aim to highlight the important role of catalytic nanomaterials in the fields of biomimetics. First, we provide a practical introduction to the identification of these nanozymes, the source of the enzyme-like activities, and the enhancement of activities via rational design and engineering. Then we briefly describe new or enhanced applications of certain nanozymes in biomedical diagnosis, environmental monitoring, and therapeutics. For instance, we have successfully used these biomimetic catalysts as colorimetric probes for the detection of

  13. 凹凸棒石黏土负载Ni催化裂解生物质焦油%Catalytic Cracking of Biomass Tar Over Ni-Based on Palygorskite

    Institute of Scientific and Technical Information of China (English)

    刘海波; 陈天虎; 石莹; 常冬寅; 宋磊; 张先龙

    2011-01-01

    Effect of Ni loading amount and reaction temperature on catalytic cracking of tar was investigated over a nickel base catalyst of palygorskite clay (Ni/PG) that was prepared by the wetness method. The morphology, phase and carbon deposition of catalysts were characterized by transmission electron microscopy, X-ray diffraction and total carbon analysis, respectively. The results show that the tar removal and hydrogen yield can be improved at a great Ni loading amount. In addition, the tar removal and hydrogen yield could be enhanced at a high reaction temperature, and the Ni loading over the Ni/PG catalyst exhibits a superior capacity of resistance to the carbon deposition.%利用浸渍法制备了凹凸棒石黏土(palygorskite,PG)Ni基催化剂(Ni/PG),探究了不同Ni负载量以及反应温度对凹凸棒石镍基催化剂催化裂解生物质焦油的影响,利用透射电镜、X射线粉末衍射、总碳等分析手段对催化剂的形貌、物相和积炭量进行表征.结果表明:活性组分高负载量有利于提高焦油去除率和氢产率;高温条件也有利于提高焦油去除率和氢产率;负载镍使得凹凸棒石镍基催化剂具有很强的抗积炭性能.

  14. Synthesis and characterization of carbazolide-based iridium PNP pincer complexes. Mechanistic and computational investigation of alkene hydrogenation: evidence for an Ir(III)/Ir(V)/Ir(III) catalytic cycle.

    Science.gov (United States)

    Cheng, Chen; Kim, Bong Gon; Guironnet, Damien; Brookhart, Maurice; Guan, Changjian; Wang, David Y; Krogh-Jespersen, Karsten; Goldman, Alan S

    2014-05-07

    New carbazolide-based iridium pincer complexes ((carb)PNP)Ir(C2H4), 3a, and ((carb)PNP)Ir(H)2, 3b, have been prepared and characterized. The dihydride, 3b, reacts with ethylene to yield the cis-dihydride ethylene complex cis-((carb)PNP)Ir(C2H4)(H)2. Under ethylene this complex reacts slowly at 70 °C to yield ethane and the ethylene complex, 3a. Kinetic analysis establishes that the reaction rate is dependent on ethylene concentration and labeling studies show reversible migratory insertion to form an ethyl hydride complex prior to formation of 3a. Exposure of cis-((carb)PNP)Ir(C2H4)(H)2 to hydrogen results in very rapid formation of ethane and dihydride, 3b. DFT analysis suggests that ethane elimination from the ethyl hydride complex is assisted by ethylene through formation of ((carb)PNP)Ir(H)(Et)(C2H4) and by H2 through formation of ((carb)PNP)Ir(H)(Et)(H2). Elimination of ethane from Ir(III) complex ((carb)PNP)Ir(H)(Et)(H2) is calculated to proceed through an Ir(V) complex ((carb)PNP)Ir(H)3(Et) which reductively eliminates ethane with a very low barrier to return to the Ir(III) dihydride, 3b. Under catalytic hydrogenation conditions (C2H4/H2), cis-((carb)PNP)Ir(C2H4)(H)2 is the catalyst resting state, and the catalysis proceeds via an Ir(III)/Ir(V)/Ir(III) cycle. This is in sharp contrast to isoelectronic (PCP)Ir systems in which hydrogenation proceeds through an Ir(III)/Ir(I)/Ir(III) cycle. The basis for this remarkable difference is discussed.

  15. Catalytic conversion of light alkanes

    Energy Technology Data Exchange (ETDEWEB)

    Lyons, J.E.

    1992-06-30

    The second Quarterly Report of 1992 on the Catalytic Conversion of Light Alkanes reviews the work done between April 1, 1992 and June 31, 1992 on the Cooperative Agreement. The mission of this work is to devise a new catalyst which can be used in a simple economic process to convert the light alkanes in natural gas to oxygenate products that can either be used as clean-burning, high octane liquid fuels, as fuel components or as precursors to liquid hydrocarbon uwspomdon fuel. During the past quarter we have continued to design, prepare, characterize and test novel catalysts for the mild selective reaction of light hydrocarbons with air or oxygen to produce alcohols directly. These catalysts are designed to form active metal oxo (MO) species and to be uniquely active for the homolytic cleavage of the carbon-hydrogen bonds in light alkanes producing intermediates which can form alcohols. We continue to investigate three molecular environments for the active catalytic species that we are trying to generate: electron-deficient macrocycles (PHASE I), polyoxometallates (PHASE II), and regular oxidic lattices including zeolites and related structures as well as other molecular surface structures having metal oxo groups (PHASE I).

  16. Catalytic reforming feed characterisation technique

    Energy Technology Data Exchange (ETDEWEB)

    Larraz Mora, R.; Arvelo Alvarez, R. [Univ. of La Laguna, Chemical Engineering Dept., La Laguna (Spain)

    2002-09-01

    The catalytic reforming of naphtha is one of the major refinery processes, designed to increase the octane number of naphtha or to produce aromatics. The naphtha used as catalytic reformer feedstock usually contains a mixture of paraffins, naphthenes, and aromatics in the carbon number range C{sub 6} to C{sub 10}. The detailed chemical composition of the feed is necessary to predict the aromatics and hydrogen production as well as the operation severity. The analysis of feed naphtha is usually reported in terms of its ASTM distillation curve and API or specific gravity. Since reforming reactions are described in terms of lumped chemical species (paraffins, naphthenes and aromatics), a feed characterisation technique should be useful in order to predict reforming operating conditions and detect feed quality changes. Unfortunately online analyzer applications as cromatography or recently introduced naphtha NMR [1] are scarce in most of refineries. This work proposes an algorithmic characterisation method focusing on its main steps description. The method could help on the subjects previously described, finally a calculation example is shown. (orig.)

  17. Development and test of a new catalytic converter for natural gas fuelled engine

    Indian Academy of Sciences (India)

    M A Kalam; H H Masjuki; M Redzuan; T M I Mahlia; M A Fuad; M Mohibah; K H Halim; A Ishak; M Khair; A Shahrir; A Yusoff

    2009-06-01

    This paper presents characteristics of a new catalytic converter (catco) to be used for natural gas fuelled engine. The catco were developed based on catalyst materials consisting of metal oxides such as titanium dioxide (TiO2) and cobalt oxide (CoO) with wire mesh substrate. Both of the catalyst materials (such as TiO2 and CoO) are inexpensive in comparison with conventional catalysts (noble metals) such as palladium or platinum. In addition, the noble metals such as platinum group metals are now identified as human health risk due to their rapid emissions in the environment from various resources like conventional catalytic converter, jewelers and other medical usages. It can be mentioned that the TiO2/CoO based catalytic converter and a new natural gas engine such as compressed natural gas (CNG) direct injection (DI) engine were developed under a research collaboration program. The original engine manufacture catalytic conveter (OEM catco) was tested for comparison purposes. The OEM catco was based on noble metal catalyst with honeycomb ceramic substrate. It is experimentally found that the conversion efficiencies of TiO2/CoO based catalytic converter are 93%, 89% and 82% for NOx, CO and HC emissions respectively. It is calculated that the TiO2/CoO based catalytic converter reduces 24%, 41% and 40% higher NOx, CO and HC emissions in comparison to OEM catco respectively. The objective of this paper is to develop a low-cost three way catalytic converter to be used with the newly developed CNG-DI engine. Detailed review on catalytic converter, low-cost catalytic converter development characteristics and CNGDI engine test results have been presented with discussions.

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

    Institute of Scientific and Technical Information of China (English)

    Wangying; WangHongzuo; 等

    1995-01-01

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

  19. Non-Catalytic Ignition System for High Performance Advanced Monopropellant Thrusters Project

    Data.gov (United States)

    National Aeronautics and Space Administration — Systima Technologies, Inc. is developing a non-catalytic ignition technology for advanced green ionic salt monopropellants such as HAN-based monopropellant AF-M315E....

  20. NOX REMOVAL WITH COMBINED SELECTIVE CATALYTIC REDUCTION AND SELECTIVE NONCATALYTIC REDUCTION: PILOT- SCALE TEST RESULTS

    Science.gov (United States)

    Pilot-scale tests were conducted to develop a combined nitrogen oxide (NOx) reduction technology using both selective catalytic reduction (SCR) and selective noncatalytic reduction (SNCR). A commercially available vanadium-and titatnium-based composite honeycomb catalyst and enh...

  1. Structure prediction of the EcoRV DNA methyltransferase based on mutant profiling, secondary structure analysis, comparison with known structures of methyltransferases and isolation of catalytically inactive single mutants.

    Science.gov (United States)

    Jeltsch, A; Sobotta, T; Pingoud, A

    1996-05-01

    The EcoRV DNA methyltransferase (M.EcoRV) is an alpha-adenine methyltransferase. We have used two different programs to predict the secondary structure of M.EcoRV. The resulting consensus prediction was tested by a mutant profiling analysis. 29 neutral mutations of M.EcoRV were generated by five cycles of random mutagenesis and selection for active variants to increase the reliability of the prediction and to get a secondary structure prediction for some ambiguously predicted regions. The predicted consensus secondary structure elements could be aligned to the common topology of the structures of the catalytic domains of M.HhaI and M.TaqI. In a complementary approach we have isolated nine catalytically inactive single mutants. Five of these mutants contain an amino acid exchange within the catalytic domain of M.EcoRV (Val2-Ala, Lys81Arg, Cys192Arg, Asp193Gly, Trp231Arg). The Trp231Arg mutant binds DNA similarly to wild-type M.EcoRV, but is catalytically inactive. Hence this mutant behaves like a bona fide active site mutant. According to the structure prediction, Trp231 is located in a loop at the putative active site of M.EcoRV. The other inactive mutants were insoluble. They contain amino acid exchanges within the conserved amino acid motifs X, III or IV in M.EcoRV confirming the importance of these regions.

  2. Development of the method of obtaining donor-acceptor complexes of titanium tetrachloride as a precursor of oxide materials based on titanium oxide and silicon matrix for the catalytically active nanoparticles of platinum group metals

    Directory of Open Access Journals (Sweden)

    A. M. Nemeryuk

    2015-12-01

    Full Text Available The method of preparation of the complex of titanium tetrachloride with dimethylformamide and reactivity when reacted with an alcohol and salts of hydrazine described. Obtained multinuclear complexes containing titanium and palladium as potential precursors of catalytically active materials.

  3. 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.

  4. Catalytic Graphitization of Phenolic Resin

    Institute of Scientific and Technical Information of China (English)

    Mu Zhao; Huaihe Song

    2011-01-01

    The catalytic graphitization of thermal plastic phenolic-formaldehyde resin with the aid of ferric nitrate (FN) was studied in detail. The morphologies and structural features of the products including onion-like carbon nanoparticles and bamboo-shaped carbon nanotubes were investigated by transmission electron microscopy (TEM), high-resolution transmission electron microscopy (HRTEM), X-ray diffraction and Raman spectroscopy measurements. It was found that with the changes of loading content of FN and residence time at 1000℃, the products exhibited various morphologies. The TEM images showed that bamboo-shaped carbon nanotube consisted of tens of bamboo sticks and onion-like carbon nanoparticle was made up of quasi-spherically concentrically closed carbon nanocages.

  5. Unsteady processes in catalytic reactors

    Energy Technology Data Exchange (ETDEWEB)

    Matros, Yu.Sh.

    1985-01-01

    In recent years a realization has occurred that reaction and reactor dynamics must be considered when designing and operating catalytic reactors. In this book, the author has focussed on both the processes occurring on individual porous-catalyst particles as well as the phenomena displayed by collections of these particles in fixed-bed reactors. The major topics discussed include the effects of unsteady-state heat and mass transfer, the influence of inhomogeneities and stagnant regions in fixed beds, and reactor operation during forced cycling of operating conditions. Despite the title of the book, attention is also paid to the determination of the number and stability of fixed-bed steady states, with the aim of describing the possibility of controlling reactors at unstable steady states. However, this development is somewhat dated, given the recent literature on multiplicity phenomena and process control.

  6. Non-catalytic recuperative reformer

    Energy Technology Data Exchange (ETDEWEB)

    Khinkis, Mark J.; Kozlov, Aleksandr P.; Kurek, Harry

    2015-12-22

    A non-catalytic recuperative reformer has a flue gas flow path for conducting hot flue gas from a thermal process and a reforming mixture flow path for conducting a reforming mixture. At least a portion of the reforming mixture flow path is embedded in the flue gas flow path to permit heat transfer from the hot flue gas to the reforming mixture. The reforming mixture flow path contains substantially no material commonly used as a catalyst for reforming hydrocarbon fuel (e.g., nickel oxide, platinum group elements or rhenium), but instead the reforming mixture is reformed into a higher calorific fuel via reactions due to the heat transfer and residence time. In a preferred embodiment, extended surfaces of metal material such as stainless steel or metal alloy that are high in nickel content are included within at least a portion of the reforming mixture flow path.

  7. Selective catalytic oxidation of ammonia

    Energy Technology Data Exchange (ETDEWEB)

    Leppaelahti, J.; Koljonen, T. [VTT Energy, Espoo (Finland)

    1996-12-31

    In the combustion of fossil fuels, the principal source of nitrogen oxides is nitrogen bound in the fuel structure. In gasification, a large part of fuel nitrogen forms NH{sub 3}, which may form nitrogen oxides during gas combustion. If NH{sub 3} and other nitrogen species could be removed from hot gas, the NO emission could be considerably reduced. However, relatively little attention has been paid to finding new means of removing nitrogen compounds from the hot gasification gas. The possibility of selectively oxidizing NH{sub 3} to N{sub 2} in the hot gasification has been studied at VTT Energy. The largest NH{sub 3} reductions have been achieved by catalytic oxidation on aluminium oxides. (author) (4 refs.)

  8. Method of fabricating a catalytic structure

    Science.gov (United States)

    Rollins, Harry W.; Petkovic, Lucia M.; Ginosar, Daniel M.

    2009-09-22

    A precursor to a catalytic structure comprising zinc oxide and copper oxide. The zinc oxide has a sheet-like morphology or a spherical morphology and the copper oxide comprises particles of copper oxide. The copper oxide is reduced to copper, producing the catalytic structure. The catalytic structure is fabricated by a hydrothermal process. A reaction mixture comprising a zinc salt, a copper salt, a hydroxyl ion source, and a structure-directing agent is formed. The reaction mixture is heated under confined volume conditions to produce the precursor. The copper oxide in the precursor is reduced to copper. A method of hydrogenating a carbon oxide using the catalytic structure is also disclosed, as is a system that includes the catalytic structure.

  9. Catalytic hot gas cleaning of gasification gas

    Energy Technology Data Exchange (ETDEWEB)

    Simell, P. [VTT Energy, Espoo (Finland). Energy Production Technologies

    1997-12-31

    The aim of this work was to study the catalytic cleaning of gasification gas from tars and ammonia. In addition, factors influencing catalytic activity in industrial applications were studied, as well as the effects of different operation conditions and limits. Also the catalytic reactions of tar and ammonia with gasification gas components were studied. The activities of different catalyst materials were measured with laboratory-scale reactors fed by slip streams taken from updraft and fluid bed gasifiers. Carbonate rocks and nickel catalysts proved to be active tar decomposing catalysts. Ammonia decomposition was in turn facilitated by nickel catalysts and iron materials like iron sinter and iron dolomite. Temperatures over 850 deg C were required at 2000{sup -1} space velocity at ambient pressure to achieve almost complete conversions. During catalytic reactions H{sub 2} and CO were formed and H{sub 2}O was consumed in addition to decomposing hydrocarbons and ammonia. Equilibrium gas composition was almost achieved with nickel catalysts at 900 deg C. No deactivation by H{sub 2}S or carbon took place in these conditions. Catalyst blocking by particulates was avoided by using a monolith type of catalyst. The apparent first order kinetic parameters were determined for the most active materials. The activities of dolomite, nickel catalyst and reference materials were measured in different gas atmospheres using laboratory apparatus. This consisted of nitrogen carrier, toluene as tar model compound, ammonia and one of the components H{sub 2}, H{sub 2}O, CO, CO{sub 2}, CO{sub 2}+H{sub 2}O or CO+CO{sub 2}. Also synthetic gasification gas was used. With the dolomite and nickel catalyst the highest toluene decomposition rates were measured with CO{sub 2} and H{sub 2}O. In gasification gas, however, the rate was retarded due to inhibition by reaction products (CO, H{sub 2}, CO{sub 2}). Tar decomposition over dolomite was modelled by benzene reactions with CO{sub 2}, H

  10. Response of sheep to supplementation of Probio-catalytic in the diets

    Directory of Open Access Journals (Sweden)

    B Haryanto

    2008-12-01

    Full Text Available biotic and catalytic supplement, on the productive performances of sheep fed Pennisetum purpuphoides (King grass. The concentrate was made of rice bran, molasses-coated palm kernel cake, minerals and salt. Probio-catalytic supplements were added either at 0.5% or 1.0% of the concentrate. The probiotic in the probio-catalytic supplements was either Probion (produced by Balitnak and assigned as probio-catalytic supplement A, or a mixture of rumen microbes of buffaloes which was assigned as probio-catalytic B. The catalytic supplement consisted of gelatinized sago, Zn, Co, urea and sulfur. Twenty heads of male young sheep with an average liveweight of 18.8 ± 1.7 kg were divided into 4 groups based on the bodyweight and allocated to 5 feeding treatments. The treatments were (1 Control (without probio-catalytic supplement, (2 R1 addition of probio-catalytic supplement A at 0.5%, (3 R2 addition of probio-catalytic supplement A at 1.0%, (4 R3 addition of probio-catalytic supplement B at 0.5%, and (5 R4 addition of probio-catalytic supplement B at 1.0%. The experiment was carried out by a randomized block design. A four-week adaptation period was then followed by a 12-week feed intake data collection and growth trial. An intake and digestibility study of the feed was carried out for 7 days. Rumen fluids were taken for analysis of pH, ammonia and volatile fatty acids and microbial population. Results indicated a significantly greater weight gain in the group received R1 than that of the other treatments. Feed dry matter intakes were less in the groups supplemented with probio-catalytic resulting in a better feed conversion ratio. The pH and concentration of ammonia of rumen fluid were not significantly different among treatments. While the acetic acid and propionic acid concentrations were not different among treatments, the butyric acid was significantly lower (P<0.05 in the groups received R3 and R4, whereas those received R2 and R3 was not

  11. Revolutionary systems for catalytic combustion and diesel catalytic particulate traps.

    Energy Technology Data Exchange (ETDEWEB)

    Stuecker, John Nicholas; Witze, Peter O.; Ferrizz, Robert Matthew; Cesarano, Joseph, III; Miller, James Edward

    2004-12-01

    This report is a summary of an LDRD project completed for the development of materials and structures conducive to advancing the state of the art for catalyst supports and diesel particulate traps. An ancillary development for bio-medical bone scaffolding was also realized. Traditionally, a low-pressure drop catalyst support, such as a ceramic honeycomb monolith, is used for catalytic reactions that require high flow rates of gases at high-temperatures. A drawback to the traditional honeycomb monoliths under these operating conditions is poor mass transfer to the catalyst surface in the straight-through channels. ''Robocasting'' is a unique process developed at Sandia National Laboratories that can be used to manufacture ceramic monoliths with alternative 3-dimensional geometries, providing tortuous pathways to increase mass transfer while maintaining low-pressure drops. These alternative 3-dimensional geometries may also provide a foundation for the development of self-regenerating supports capable of trapping and combusting soot particles from a diesel engine exhaust stream. This report describes the structures developed and characterizes the improved catalytic performance that can result. The results show that, relative to honeycomb monolith supports, considerable improvement in mass transfer efficiency is observed for robocast samples synthesized using an FCC-like geometry of alternating rods. Also, there is clearly a trade-off between enhanced mass transfer and increased pressure drop, which can be optimized depending on the particular demands of a given application. Practical applications include the combustion of natural gas for power generation, production of syngas, and hydrogen reforming reactions. The robocast lattice structures also show practicality for diesel particulate trapping. Preliminary results for trapping efficiency are reported as well as the development of electrically resistive lattices that can regenerate the structure

  12. Preparation of Photo catalytic Materials Based on Bi{sub 4}Ti{sub 3}O{sub 1}2 Doped with Transition Metals; Preparacion de Materiales Fotocatalizadores Basados en Bi{sub 4}Ti{sub 3}O{sub 1}2 Dopados con Metales de Transicion

    Energy Technology Data Exchange (ETDEWEB)

    Calatalyud, D. G.; Rodriguez, M.; Gallego, B.; Fernandez-Hevia, D.; Jardiel, T.

    2012-07-01

    The production of hydrogen from water using ceramic semiconductors with photo catalytic properties has gained special relevance in the last years, due to their potential use for the generation of hydrogen in a direct and clean way. Doping with transition metals has demonstrated to be an effective method to obtain new active photo catalysts in the visible range of the solar spectrum by changing the band gap of the material. In this paper we study the effect of the addition of various dopants (Fe, Ni, Cr, Mn, Co, Cu) in the structure and band gap of Bi{sub 4}Ti{sub 3}O{sub 1}2, in order to improve its photo catalytic activity and make it visible light active. Accordingly, doped BIT based materials have been obtained by solid state processing and different amounts of an additional phase with sillenite structure, Bi{sub 1}2TiO{sub 2}0, have been detected. With the dopant a shift of the absorption spectra is produced towards higher wavelengths and consequently towards lower band gap values. The band gap values obtained for many of the prepared compositions are quite promising, promoting the study of their catalytic properties.. (Author)

  13. Cerium: catalytic properties, technological and environmental applications; Cerio: propriedades cataliticas, aplicacoes tecnologicas e ambientais

    Energy Technology Data Exchange (ETDEWEB)

    Martins, Tereza S. [Universidade de Sao Paulo (USP), SP (Brazil). Inst. de Fisica; Hewer, Thiago L.R. [Universidade de Sao Paulo (USP), SP (Brazil). Inst. de Quimica; Freire, Renato S. [Universidade de Sao Paulo (USP), Cubatao (Brazil). Centro de Capacitacao e Pesquisa em Meio Ambiente]. E-mail: tmartins@if.usp.br

    2007-07-01

    Cerium based-compounds have great importance in a wide range of technological applications, such as: fuel cell devices development; metallurgic processes, petroleum refining; glass and ceramic production. Recently, its catalytic properties have been also explored for environmental applications, especially those to prevent or to control atmospheric and water pollution. Subjects covered in this work include a brief description of the fundaments of cerium catalytic properties and some relevant technological applications. Special attention is given to its photo catalytic activity and its ability to degrade pollutants. Recent results and future prospect about these applications are also evaluated. (author)

  14. Formaldehyde: catalytic oxidation as a promising soft way of elimination.

    Science.gov (United States)

    Quiroz Torres, Jhon; Royer, Sébastien; Bellat, Jean-Pierre; Giraudon, Jean-Marc; Lamonier, Jean-François

    2013-04-01

    Compared to other molecules such as benzene, toluene, xylene, and chlorinated compounds, the catalytic oxidation of formaldehyde has been studied rarely. However, standards for the emission level of this pollutant will become more restrictive because of its extreme toxicity even at very low concentrations in air. As a consequence, the development of a highly efficient process for its selective elimination is needed. Complete catalytic oxidation of formaldehyde into CO2 and H2 O using noble-metal-based catalysts is a promising method to convert this pollutant at room temperature, making this process energetically attractive from an industrial point of view. However, the development of a less expensive active phase is required for a large-scale industrial development. Nanomaterials based on oxides of manganese are described as the most promising catalysts. The objective of this Minireview is to present promising recent studies on the removal of formaldehyde through heterogeneous catalysis to stimulate future research in this topic.

  15. Catalytic asymmetric synthesis of biologically important 3-hydroxyoxindoles: an update

    Directory of Open Access Journals (Sweden)

    Bin Yu

    2016-05-01

    Full Text Available Oxindole scaffolds are prevalent in natural products and have been recognized as privileged substructures in new drug discovery. Several oxindole-containing compounds have advanced into clinical trials for the treatment of different diseases. Among these compounds, enantioenriched 3-hydroxyoxindole scaffolds also exist in natural products and have proven to possess promising biological activities. A large number of catalytic asymmetric strategies toward the construction of 3-hydroxyoxindoles based on transition metal catalysis and organocatalysis have been reported in the last decades. Additionally, 3-hydroxyoxindoles as versatile precursors have also been used in the total synthesis of natural products and for constructing structurally novel scaffolds. In this review, we aim to provide an overview about the catalytic asymmetric synthesis of biologically important 3-substituted 3-hydroxyoxindoles and 3-hydroxyoxindole-based further transformations.

  16. Catalytic asymmetric synthesis of biologically important 3-hydroxyoxindoles: an update

    Science.gov (United States)

    2016-01-01

    Summary Oxindole scaffolds are prevalent in natural products and have been recognized as privileged substructures in new drug discovery. Several oxindole-containing compounds have advanced into clinical trials for the treatment of different diseases. Among these compounds, enantioenriched 3-hydroxyoxindole scaffolds also exist in natural products and have proven to possess promising biological activities. A large number of catalytic asymmetric strategies toward the construction of 3-hydroxyoxindoles based on transition metal catalysis and organocatalysis have been reported in the last decades. Additionally, 3-hydroxyoxindoles as versatile precursors have also been used in the total synthesis of natural products and for constructing structurally novel scaffolds. In this review, we aim to provide an overview about the catalytic asymmetric synthesis of biologically important 3-substituted 3-hydroxyoxindoles and 3-hydroxyoxindole-based further transformations. PMID:27340490

  17. A double signal electrochemical human immunoglobulin G immunosensor based on gold nanoparticles-polydopamine functionalized reduced graphene oxide as a sensor platform and AgNPs/carbon nanocomposite as signal probe and catalytic substrate.

    Science.gov (United States)

    Zhang, Si; Huang, Na; Lu, Qiujun; Liu, Meiling; Li, Haitao; Zhang, Youyu; Yao, Shouzhuo

    2016-03-15

    In this paper, a double signal electrochemical Human immunoglobulin G (HIgG) immunosensor based on AgNPs/carbon nanocomposite (Ag/C NC) as the signal probe and catalytic substrate was developed for fast and sensitive detection of HIgG. The as-prepared AuNPs-PDA-rGO nanocomposite and Ag/C NC were confirmed by UV-vis, Fourier transform infrared spectroscopy, scanning electron microscopy and transmission electron microscopy. Electrochemical impedance spectroscopy, cyclic voltammetry and differential pulse voltammetry were used to investigate the electrochemical properties of the proposed immunosensor. The AuNPs-PDA-rGO nanocomposite can improve the electron transfer rate and capture more Ab1. In the sandwich-type immunoassay process, the Ag/C NC functionalized bioconjugates were captured on HIgG/Ab1/AuNPs-PDA-rGO surface and the electrochemical double-signal strategy was employed. These double electrochemical detection signals were directly monitored the oxidation current originated from Ag/C NC and indirectly detected the reduction current of benzoquinone which was produced from the reaction of H2O2 and HQ by catalysis of Ag/C NC in electrochemical detection of HIgG. Under the optimized conditions, the current responses were changed with the concentrations of HIgG for the proposed immunosensor with wide linear ranges of 0.1 to 100 ngmL(-1) and 0.01-100 ngmL(-1) with the lowest detection concentration of 0.001 ng mL(-1) in the absence and presence of H2O2 and HQ. The double-signal strategy is used for detection of HIgG, and the results came from the two signals were well consistent with each other. The proposed immunosensor was successfully applied in analysis of human IgG in real samples and this strategy may provide a relative simple and effective method for construction of other immunsensors in detection of other biomarkers in clinical medicine.

  18. Storage of hydrogen in floating catalytic carbon nanotubes after graphitizing

    Institute of Scientific and Technical Information of China (English)

    朱宏伟; 李雪松; 慈立杰; 徐才录; 毛宗强; 梁吉; 吴德海

    2002-01-01

    Hydrogen storage under moderate pressure (~10 Mpa) and ambient temperature (~25℃) in multi-walled carbon nanotubes (MWNTs) prepared by the floating catalyst method is investigated. The capacity of hydrogen adsorption is evaluated based on both the nanotubes diameter and morphology. Indirect evidence indicates that hydrogen adsorption not only occurs on tube surface and interiors, but also in tube interlayers. The results show that the floating catalytic carbon nanotubes might be a candidate hydrogen storage material for fuel cell electric vehicles.

  19. Topological entropy of catalytic sets: Hypercycles revisited

    Science.gov (United States)

    Sardanyés, Josep; Duarte, Jorge; Januário, Cristina; Martins, Nuno

    2012-02-01

    The dynamics of catalytic networks have been widely studied over the last decades because of their implications in several fields like prebiotic evolution, virology, neural networks, immunology or ecology. One of the most studied mathematical bodies for catalytic networks was initially formulated in the context of prebiotic evolution, by means of the hypercycle theory. The hypercycle is a set of self-replicating species able to catalyze other replicator species within a cyclic architecture. Hypercyclic organization might arise from a quasispecies as a way to increase the informational containt surpassing the so-called error threshold. The catalytic coupling between replicators makes all the species to behave like a single and coherent evolutionary multimolecular unit. The inherent nonlinearities of catalytic interactions are responsible for the emergence of several types of dynamics, among them, chaos. In this article we begin with a brief review of the hypercycle theory focusing on its evolutionary implications as well as on different dynamics associated to different types of small catalytic networks. Then we study the properties of chaotic hypercycles with error-prone replication with symbolic dynamics theory, characterizing, by means of the theory of topological Markov chains, the topological entropy and the periods of the orbits of unimodal-like iterated maps obtained from the strange attractor. We will focus our study on some key parameters responsible for the structure of the catalytic network: mutation rates, autocatalytic and cross-catalytic interactions.

  20. New self-assembled material based on Ru nanoparticles and 4-sulfocalix[4]arene as an efficient and recyclable catalyst for reduction of brilliant yellow azo dye in water: a new model catalytic reaction

    Science.gov (United States)

    Rambabu, Darsi; Pradeep, Chullikkattil P.; Dhir, Abhimanew

    2016-12-01

    New self-assembled material ( Ru@SC) with ruthenium nanoparticles (Ru NPs) and 4-sulfocalix[4]arene (SC) is synthesized in water at room temperature. Ru@SC is characterized by thermal gravimetric analysis, FT-IR, powder x-ray diffraction, TEM and SEM analysis. The size of Ru nanoparticles in the self-assembly is approximately 5 nm. The self-assembled material Ru@SC shows an efficient catalytic reduction of toxic `brilliant yellow' (BY) azo dye. The reduced amine products were successfully separated and confirmed by single-crystal XRD, NMR and UV-Vis spectroscopy. Ru@SC showed a better catalytic activity in comparison with commercial catalysts Ru/C (ruthenium on charcoal 5 %) and Pd/C (palladium on charcoal 5 and 10 %). The catalyst also showed a promising recyclability and heterogeneous nature as a catalyst for reduction of `BY' azo dye.

  1. Synthesis of Fe3O4@SiO2-Ag magnetic nanocomposite based on small-sized and highly dispersed silver nanoparticles for catalytic reduction of 4-nitrophenol.

    Science.gov (United States)

    Chi, Yue; Yuan, Qing; Li, Yanjuan; Tu, Jinchun; Zhao, Liang; Li, Nan; Li, Xiaotian

    2012-10-01

    In this work, we report a facile method to generate core-shell structured Fe(3)O(4)@SiO(2)-Ag magnetic nanocomposite by an in situ wet chemistry route with the aid of polyvinylpyrrolidone as both reductant and stabilizer. This method can effectively prevent Ag nanoparticles from aggregating on the silica surface, thus resulting highly dispersed and small-sized Ag nanoparticles. The as-prepared nanocomposite is composed of a central magnetite core with a strong response to external fields, an interlayer of SiO(2), and numerous highly dispersed Ag nanoparticles with a narrow size distribution. Furthermore, the Fe(3)O(4)@SiO(2)-Ag nanocomposite showed high performance in the catalytic reduction of 4-nitrophenol and could be easily recycled by applying an external magnetic field while maintaining the catalytic activity without significant decrease even after running 15 times.

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

    Institute of Scientific and Technical Information of China (English)

    过玮; 何盈盈; 宋俊峰

    2003-01-01

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

  3. Activity prediction of substrates in NADH-dependent carbonyl reductase by docking requires catalytic constraints and charge parameterization of catalytic zinc environment.

    Science.gov (United States)

    Dhoke, Gaurao V; Loderer, Christoph; Davari, Mehdi D; Ansorge-Schumacher, Marion; Schwaneberg, Ulrich; Bocola, Marco

    2015-11-01

    Molecular docking of substrates is more challenging compared to inhibitors as the reaction mechanism has to be considered. This becomes more pronounced for zinc-dependent enzymes since the coordination state of the catalytic zinc ion is of greater importance. In order to develop a predictive substrate docking protocol, we have performed molecular docking studies of diketone substrates using the catalytic state of carbonyl reductase 2 from Candida parapsilosis (CPCR2). Different docking protocols using two docking methods (AutoDock Vina and AutoDock4.2) with two different sets of atomic charges (AM1-BCC and HF-RESP) for catalytic zinc environment and substrates as well as two sets of vdW parameters for zinc ion were examined. We have selected the catalytic binding pose of each substrate by applying mechanism based distance criteria. To compare the performance of the docking protocols, the correlation plots for the binding energies of these catalytic poses were obtained against experimental Vmax values of the 11 diketone substrates for CPCR2. The best correlation of 0.73 was achieved with AutoDock4.2 while treating catalytic zinc ion in optimized non-bonded (NBopt) state with +1.01 charge on the zinc ion, compared to 0.36 in non-bonded (+2.00 charge on the zinc ion) state. These results indicate the importance of catalytic constraints and charge parameterization of catalytic zinc environment for the prediction of substrate activity in zinc-dependent enzymes by molecular docking. The developed predictive docking protocol described here is in principle generally applicable for the efficient in silico substrate spectra characterization of zinc-dependent ADH.

  4. Microchannel Reactor System for Catalytic Hydrogenation

    Energy Technology Data Exchange (ETDEWEB)

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

    2010-12-22

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

  5. Catalytic production of conjugated fatty acids and oils.

    Science.gov (United States)

    Philippaerts, An; Goossens, Steven; Jacobs, Pierre A; Sels, Bert F

    2011-06-20

    The reactive double bonds in conjugated vegetable oils are of high interest in industry. Traditionally, conjugated vegetable oils are added to paints, varnishes, and inks to improve their drying properties, while recently there is an increased interest in their use in the production of bioplastics. Besides the industrial applications, also food manufactures are interested in conjugated vegetable oils due to their various positive health effects. While the isomer type is less important for their industrial purposes, the beneficial health effects are mainly associated with the c9,t11, t10,c12 and t9,t11 CLA isomers. The production of CLA-enriched oils as additives in functional foods thus requires a high CLA isomer selectivity. Currently, CLAs are produced by conjugation of oils high in linoleic acid, for example soybean and safflower oil, using homogeneous bases. Although high CLA productivities and very high isomer selectivities are obtained, this process faces many ecological drawbacks. Moreover, CLA-enriched oils can not be produced directly with the homogeneous bases. Literature reports describe many catalytic processes to conjugate linoleic acid, linoleic acid methyl ester, and vegetable oils rich in linoleic acid: biocatalysts, for example enzymes and cells; metal catalysts, for example homogeneous metal complexes and heterogeneous catalysts; and photocatalysts. This Review discusses state-of-the-art catalytic processes in comparison with some new catalytic production routes. For each category of catalytic process, the CLA productivities and the CLA isomer selectivity are compared. Heterogeneous catalysis seems the most attractive approach for CLA production due to its easy recovery process, provided that the competing hydrogenation reaction is limited and the CLA production rate competes with the current homogeneous base catalysis. The most important criteria to obtain high CLA productivity and isomer selectivity are (1) absence of a hydrogen donor, (2

  6. First-Principles Calculation, Synthesis, and Catalytic Properties of Rh-Cu Alloy Nanoparticles.

    Science.gov (United States)

    Komatsu, Tokutaro; Kobayashi, Hirokazu; Kusada, Kohei; Kubota, Yoshiki; Takata, Masaki; Yamamoto, Tomokazu; Matsumura, Syo; Sato, Katsutoshi; Nagaoka, Katsutoshi; Kitagawa, Hiroshi

    2017-01-01

    The first synthesis of pure Rh1-x Cux solid-solution nanoparticles is reported. In contrast to the bulk state, the solid-solution phase was stable up to 750 °C. Based on facile density-functional calculations, we made a prediction that the catalytic activity of Rh1-x Cux can be maintained even with 50 at % replacement of Rh with Cu. The prediction was confirmed for the catalytic activities on CO and NOx conversions.

  7. Catalytic Chemistry on Oxide Nanostructures

    Energy Technology Data Exchange (ETDEWEB)

    Asthagiri, Aravind; Dixon, David A.; Dohnalek, Zdenek; Kay, Bruce D.; Rodriquez, Jose A.; Rousseau, Roger J.; Stacchiola, Dario; Weaver, Jason F.

    2016-05-29

    Metal oxides represent one of the most important and widely employed materials in catalysis. Extreme variability of their chemistry provides a unique opportunity to tune their properties and to utilize them for the design of highly active and selective catalysts. For bulk oxides, this can be achieved by varying their stoichiometry, phase, exposed surface facets, defect, dopant densities and numerous other ways. Further, distinct properties from those of bulk oxides can be attained by restricting the oxide dimensionality and preparing them in the form of ultrathin films and nanoclusters as discussed throughout this book. In this chapter we focus on demonstrating such unique catalytic properties brought by the oxide nanoscaling. In the highlighted studies planar models are carefully designed to achieve minimal dispersion of structural motifs and to attain detailed mechanistic understanding of targeted chemical transformations. Detailed level of morphological and structural characterization necessary to achieve this goal is accomplished by employing both high-resolution imaging via scanning probe methods and ensemble-averaged surface sensitive spectroscopic methods. Three prototypical examples illustrating different properties of nanoscaled oxides in different classes of reactions are selected.

  8. Pyridoxal-5'-phosphate-dependent catalytic antibodies.

    Science.gov (United States)

    Gramatikova, Svetlana; Mouratou, Barbara; Stetefeld, Jörg; Mehta, Perdeep K; Christen, Philipp

    2002-11-01

    Strategies for expanding the catalytic scope of antibodies include the incorporation of inorganic or organic cofactors into their binding sites. An obvious choice is pyridoxal-5'-phosphate (PLP), which is probably the most versatile organic cofactor of enzymes. Monoclonal antibodies against the hapten N(alpha)-(5'-phosphopyridoxyl)-L-lysine, a stable analog of the covalent coenzyme-substrate adducts were screened by a competition ELISA for binding of the PLP-amino acid Schiff base adduct. The Schiff base with its C4'-N alpha double bond is, in contrast to the hapten, a planar compound and is an obligatory intermediate in all PLP-dependent reactions of amino acids. This highly discriminating screening step eliminated all but 5 of 24 hapten-binding antibodies. The five remaining antibodies were tested for catalysis of the PLP-dependent alpha,beta-elimination reaction of beta-chloroalanine. Antibody 15A9 complied with this selection criterion and catalyzed in addition the cofactor-dependent transamination reaction of hydrophobic D-amino acids and oxo acids (k(cat)'=0.42 min(-1) with D-alanine at 25 degrees C). Homology modeling together with alanine scanning yielded a 3D model of Fab 15A9. The striking analogy between antibody 15A9 and PLP-dependent enzymes includes the following features: (1) The binding sites accommodate the planar coenzyme-amino acid adduct. (2) The bond at C alpha to be broken lies together with the C alpha-N bond in a plane orthogonal to the plane of coenzyme and imine bond. (3) The alpha-carboxylate group of the substrate is bound by an arginine residue. (4) The coenzyme-substrate adduct assumes a cisoid conformation. (5) PLP markedly contributes to catalytic efficiency, being a 10(4) times more efficient amino group acceptor than pyruvate. The protein moiety, however, ensures reaction as well as substrate specificity, and further accelerates the reaction (in 15A9 k(cat (Ab x PLP))'/k(cat (PLP))'=5 x 10(3)). The analogies of antibody 15A9 with

  9. Catalytic models developed through social work

    DEFF Research Database (Denmark)

    Jensen, Mogens

    2015-01-01

    The article develops the concept of catalytic processes in relation to social work with adolescents in an attempt to both reach a more nuanced understanding of social work and at the same time to develop the concept of catalytic processes in psychology. The social work is pedagogical treatment...... of adolescents placed in out-of-home care and is characterised using three situated cases as empirical data. Afterwards the concept of catalytic processes is briefly presented and then applied in an analysis of pedagogical treatment in the three cases. The result is a different conceptualisation of the social...... work with new possibilities of development of the work, but also suggestions for development of the concept of catalytic processes....

  10. Catalytic converters as a source of platinum

    Directory of Open Access Journals (Sweden)

    A. Fornalczyk

    2011-10-01

    Full Text Available The increase of Platinum Group Metals demand in automotive industry is connected with growing amount of cars equipped with the catalytic converters. The paper presents the review of available technologies during recycling process. The possibility of removing platinum from the used catalytic converters applying pyrometallurgical and hyrdometallurgical methods were also investigated. Metals such as Cu, Pb, Ca, Mg, Cd were used in the pyrometallurgical research (catalytic converter was melted with Cu, Pb and Ca or Mg and Cd vapours were blown through the whole carrier. In hydrometallurgical research catalytic converters was dissolved in aqua regia. Analysis of Pt contents in the carrier before and after the process was performed by means of atomic absorption spectroscopy. Obtained result were discussed.

  11. Catalytic Asymmetric Synthesis of Phosphine Boronates

    NARCIS (Netherlands)

    Hornillos, Valentin; Vila, Carlos; Otten, Edwin; Feringa, Ben L.

    2015-01-01

    The first catalytic enantioselective synthesis of ambiphilic phosphine boronate esters is presented. The asymmetric boration of ,-unsaturated phosphine oxides catalyzed by a copper bisphosphine complex affords optically active organoboronate esters that bear a vicinal phosphine oxide group in good y

  12. Green synthesis and catalytic application of curcumin stabilized silver nanoparticles

    Indian Academy of Sciences (India)

    A D VERMA; N JAIN; S K SINGHA; M A QURAISHI; I SINHA

    2016-12-01

    An ultrasonication based green synthesis approach was used to prepare curcumin-stabilized silver nanoparticles (c-AgNPs). Nanoparticles thus obtained were characterized by UV-Visible spectroscopy, X-ray diffraction (XRD), Transmission electron microscopy (TEM) and Fourier transform infrared spectroscopy (FTIR). Two different size distributions of c-AgNPs were obtained by changing the ratio of curcumin to silver salt precursor. These c-AgNPs were used as catalysts in the catalytic reduction of p-nitrophenol to p-aminophenol. The c-AgNPs with narrower size distribution exhibited better catalytic activity as well as lower activation energy. Variation of apparent rate constant with the reactant concentration agreed with the Langmuir- Hinshelwood (LH) model. Consequently, the surface rate constant related to the rate-determining step and the respective adsorption constants of p-nitrophenol and of borohydride were determined as per this model.

  13. Catalytic wet hydrogen peroxide oxidation of a petrochemical wastewater.

    Science.gov (United States)

    Pariente, M I; Melero, J A; Martínez, F; Botas, J A; Gallego, A I

    2010-01-01

    Continuous Catalytic Wet Hydrogen Peroxide Oxidation (CWHPO) for the treatment of a petrochemical industry wastewater has been studied on a pilot plant scale process. The installation, based on a catalytic fixed bed reactor (FBR) coupled with a stirred tank reactor (STR), shows an interesting alternative for the intensification of a continuous CWHPO treatment. Agglomerated SBA-15 silica-supported iron oxide (Fe(2)O(3)/SBA-15) was used as Fenton-like catalyst. Several variables such as the temperature and hydrogen peroxide concentration, as well as the capacity of the pilot plant for the treatment of inlet polluted streams with different dilution degrees were studied. Remarkable results in terms of TOC reduction and increased biodegradability were achieved using 160 degrees C and moderate hydrogen peroxide initial concentration. Additionally, a good stability of the catalyst was evidenced for 8 hours of treatment with low iron leaching (less than 1 mg/L) under the best operating conditions.

  14. Mechanism of Transition-Metal Nanoparticle Catalytic Graphene Cutting.

    Science.gov (United States)

    Ma, Liang; Wang, Jinlan; Yip, Joanne; Ding, Feng

    2014-04-03

    Catalytic cutting by transition-metal (TM) particles is a promising method for the synthesizing of high-quality graphene quantum dots and nanoribbons with smooth edges. Experimentally, it is observed that the cutting always results in channels with zigzag (ZZ) or armchair (AC) edges. However, the driving force that is responsible for such a cutting behavior remains a puzzle. Here, by calculating the interfacial formation energies of the TM-graphene edges with ab initio method, we show that the surface of a catalyst particle tends to be aligned along either AC or ZZ direction of the graphene lattice, and thus the cutting of graphene is guided as such. The different cutting behaviors of various catalysts are well-explained based on the competition between TM-passivated graphene edges and the etching-agent-terminated ones. Furthermore, the kinetics of graphene catalytic cutting along ZZ and AC directions, respectively, are explored at the atomic level.

  15. MOBILE COMPLEX FOR CATALYTIC THERMAL WASTE TREATMENT

    Directory of Open Access Journals (Sweden)

    Vedi V.E.

    2012-12-01

    Full Text Available The design and purpose of the basic units of the mobile waste processing complex “MPK” are described. Experimental data of catalytic purification of exhaust gases are presented. Experimental data on catalytic clearing of final gases of a designed mobile incinerator plant are shown. It is defined, that concentrating of parasitic bridging in waste gases of the complex are considerably smaller, rather than allowed by normative documents.

  16. Structural basis for catalytically restrictive dynamics of a high-energy enzyme state

    Science.gov (United States)

    Kovermann, Michael; Ådén, Jörgen; Grundström, Christin; Elisabeth Sauer-Eriksson, A.; Sauer, Uwe H.; Wolf-Watz, Magnus

    2015-07-01

    An emerging paradigm in enzymology is that transient high-energy structural states play crucial roles in enzymatic reaction cycles. Generally, these high-energy or `invisible' states cannot be studied directly at atomic resolution using existing structural and spectroscopic techniques owing to their low populations or short residence times. Here we report the direct NMR-based detection of the molecular topology and conformational dynamics of a catalytically indispensable high-energy state of an adenylate kinase variant. On the basis of matching energy barriers for conformational dynamics and catalytic turnover, it was found that the enzyme's catalytic activity is governed by its dynamic interconversion between the high-energy state and a ground state structure that was determined by X-ray crystallography. Our results show that it is possible to rationally tune enzymes' conformational dynamics and hence their catalytic power--a key aspect in rational design of enzymes catalysing novel reactions.

  17. Structural models of vanadate-dependent haloperoxidases, their reactivity, immobilization on polymer support and catalytic activities

    Indian Academy of Sciences (India)

    Mannar R Maurya

    2011-03-01

    The design of structural and functional models of enzymes vanadate-dependent haloperoxidases (VHPO) and the isolation and/or generation of species having {VO(H2O)}, {VO2}, {VO(OH)} and {VO(O2)} cores, proposed as intermediate(s) during catalytic action, in solution have been studied. Catalytic potential of these complexes have been tested for oxo-transfer as well as oxidative bromination and sulfide oxidation reactions. Some of the oxidovanadium(IV) and dioxidovanadium(V) complexes have been immobilized on polymer support in order to improve their recycle ability during catalytic activities and turn over number. The formulations of the polymer-anchored complexes are based on the respective neat complexes and conclusions drawn from the various characterization studies. These catalysts have successfully been used for all catalytic reactions mentioned above. These catalysts are stable and recyclable.

  18. Computational design of chemically propelled catalytic nanorotors.

    Science.gov (United States)

    Chen, Yanping; Shi, Yunfeng

    2013-08-14

    We designed catalytic nanorotors and investigated the rotational motion and energy conversion efficiency using reactive molecular dynamics in two dimensions. First, a two-arm nanorotor was constructed by decorating a slender beam with catalysts asymmetrically on its two long edges, while fixing the beam center as the rotational axis. Autonomous rotation was observed for the two-arm nanorotor immersing in a fuel environment. Here fuel molecules undergo exothermic combination reaction facilitated by the catalysts. It was found that the angular velocity increases with the catalyst coverage parabolically, while the rotary nanomotor efficiency stays roughly constant. These observations are consistent with a single-collision-momentum-transfer-based propulsion model. Furthermore, multi-arm nanorotors (up to eight arms) were constructed by carving radially distributed arms followed by decorating catalysts. For multi-arm nanorotors, both the angular velocity and the efficiency decrease as the number of arms increases. These behaviors contradict the aforementioned model, which are likely due to the deceleration from secondary collisions between products and the nanorotor arms. Our simulation results show that the optimal design for a nanorotor that maximizes its angular velocity and the motor efficiency is a two-arm nanorotor with nearly full coverage of catalysts.

  19. Adsorbent catalytic nanoparticles and methods of using the same

    Energy Technology Data Exchange (ETDEWEB)

    Slowing, Igor Ivan; Kandel, Kapil

    2017-01-31

    The present invention provides an adsorbent catalytic nanoparticle including a mesoporous silica nanoparticle having at least one adsorbent functional group bound thereto. The adsorbent catalytic nanoparticle also includes at least one catalytic material. In various embodiments, the present invention provides methods of using and making the adsorbent catalytic nanoparticles. In some examples, the adsorbent catalytic nanoparticles can be used to selectively remove fatty acids from feedstocks for biodiesel, and to hydrotreat the separated fatty acids.

  20. Zn、Mo对CuCo基催化剂合成低碳醇性能的促进作用%Catalytic Properties for Higher-alcohol Synthesis of CuCo Based Catalysts Promoted by Transition Elements(Zn,Mo)

    Institute of Scientific and Technical Information of China (English)

    士丽敏; 储伟

    2011-01-01

    采用超声辅助的反相共沉淀法制备CO加氢合成低碳醇用CuCo基催化剂,研究过渡金属Zn、Mo助剂对CuCo基催化剂结构与性能的影响,借助N2吸附(BET)、X射线衍射(XRD)、程序升温还原(H2-TPR)和程序升温脱附(CO-TPD)等测试技术对催化剂进行表征.结果表明,Zn、Mo均在一定程度上增加了催化剂的比表面积、降低晶粒尺寸且保持Cu-Co尖晶石的主相结构.助剂Zn的添加对比表面积提高有限,降低了催化剂表面对CO物种的吸附量,CO转化率和醇产率有所减少;Mo助剂的存在显著提高了比表面积,促进了铜钴的分散,改善了氧化还原性能,使催化剂的加氢能力、CO转化率和醇产率均显著提高;Zn、Mo助剂的加入均促进了甲醇的形成.%CuCo-based catalysts for CO hydrogenation to higher alcohols were prepared by the ultrasound assisted reverse coprecipitation.Effects of transition elements(Zn,Mo) on the structure and catalytic performance were investigated.The catalysts were characterized by means of X-ray diffraction(XRD),N2 adsorption isotherm(BET),temperature-programmed reduction(H2-TPR) and temperature-programmed desorption(CO-TPD) techniques.The specific surface areas of the experimental catalysts were increased while the crystallite sizes were decreased by the addition Zn and Mo without changing the Cu-Co spinel crystal structure.For the Zn contained catalyst,the increase of specific surface area was limited and amount of adsorbed CO-species was decreased.Both CO conversion and alcohol yield were reduced.For the Mo promoted sample,the specific surface area was increased obviously.Meanwhile,the dispersion of copper and cobalt was promoted and the reducibility was improved.As a result,the hydrogenation ability,CO conversion and alcohol yield were increased significantly.With the addition of Zn and Mo,the contents of methanol in mixed alcohols were increased comparing with that of Cu

  1. Recyclable Nanostructured Catalytic Systems in Modern Environmentally Friendly Organic Synthesis

    Directory of Open Access Journals (Sweden)

    Irina Beletskaya

    2010-07-01

    Full Text Available Modern chemical synthesis makes heavy use of different types of catalytic systems: homogeneous, heterogeneous and nano-sized. The latter – nano-sized catalysts – have given rise in the 21st century to a rapidly developing area of research encompassing several prospects and opportunities for new technologies. Catalytic reactions ensure high regio- and stereoselectivity of chemical transformations, as well as better yields and milder reaction conditions. In recent years several novel catalytic systems were developed for selective formation of carbon-heteroatom and carbon-carbon bonds. This review presents the achievements of our team in our studies on various types of catalysts containing metal nanoparticles: palladium-containing diblock copolymer micelles; soluble palladium-containing polymers; metallides on a support; polymeric metal salts and oxides; and, in addition, metal-free organic catalysts based on soluble polymers acting as nanoreactors. Representative examples are given and discussed in light of possible applications to solve important problems in modern organic synthesis.

  2. Catalytic strategy used by the myosin motor to hydrolyze ATP.

    Science.gov (United States)

    Kiani, Farooq Ahmad; Fischer, Stefan

    2014-07-22

    Myosin is a molecular motor responsible for biological motions such as muscle contraction and intracellular cargo transport, for which it hydrolyzes adenosine 5'-triphosphate (ATP). Early steps of the mechanism by which myosin catalyzes ATP hydrolysis have been investigated, but still missing are the structure of the final ADP·inorganic phosphate (Pi) product and the complete pathway leading to it. Here, a comprehensive description of the catalytic strategy of myosin is formulated, based on combined quantum-classical molecular mechanics calculations. A full exploration of catalytic pathways was performed and a final product structure was found that is consistent with all experiments. Molecular movies of the relevant pathways show the different reorganizations of the H-bond network that lead to the final product, whose γ-phosphate is not in the previously reported HPγO4(2-) state, but in the H2PγO4(-) state. The simulations reveal that the catalytic strategy of myosin employs a three-pronged tactic: (i) Stabilization of the γ-phosphate of ATP in a dissociated metaphosphate (PγO3(-)) state. (ii) Polarization of the attacking water molecule, to abstract a proton from that water. (iii) Formation of multiple proton wires in the active site, for efficient transfer of the abstracted proton to various product precursors. The specific role played in this strategy by each of the three loops enclosing ATP is identified unambiguously. It explains how the precise timing of the ATPase activation during the force generating cycle is achieved in myosin. The catalytic strategy described here for myosin is likely to be very similar in most nucleotide hydrolyzing enzymes.

  3. Catalytic Combustion for Ultra-Low NOx Hydrogen Turbines

    Energy Technology Data Exchange (ETDEWEB)

    Etemad, Shahrokh; Baird, Benjamin; Alavandi, Sandeep

    2011-06-30

    Precision Combustion, Inc., (PCI) in close collaboration with Solar Turbines, Incorporated, has developed and demonstrated a combustion system for hydrogen fueled turbines that reduces NOx to low single digit level while maintaining or improving current levels of efficiency and eliminating emissions of carbon dioxide. Full scale Rich Catalytic Hydrogen (RCH1) injector was developed and successfully tested at Solar Turbines, Incorporated high pressure test facility demonstrating low single digit NOx emissions for hydrogen fuel in the range of 2200F-2750F. This development work was based on initial subscale development for faster turnaround and reduced cost. Subscale testing provided promising results for 42% and 52% H2 with NOx emissions of less than 2 ppm with improved flame stability. In addition, catalytic reactor element testing for substrate oxidation, thermal cyclic injector testing to simulate start-stop operation in a gas turbine environment, and steady state 15 atm. operation testing were performed successfully. The testing demonstrated stable and robust catalytic element component life for gas turbine conditions. The benefit of the catalytic hydrogen combustor technology includes capability of delivering near-zero NOx without costly post-combustion controls and without requirement for added sulfur control. In addition, reduced acoustics increase gas turbine component life. These advantages advances Department of Energy (DOE’s) objectives for achievement of low single digit NOx emissions, improvement in efficiency vs. postcombustion controls, fuel flexibility, a significant net reduction in Integrated Gasification Combined Cycle (IGCC) system net capital and operating costs, and a route to commercialization across the power generation field from micro turbines to industrial and utility turbines.

  4. Catalytic coal liquefaction. Final report

    Energy Technology Data Exchange (ETDEWEB)

    Weller, S W

    1981-01-01

    Monolith catalysts of MoO/sub 3/-CoO-Al/sub 2/O/sub 3/ were prepared and tested for coal liquefaction in a stirred autoclave. In general, the monolith catalysts were not as good as particulate catalysts prepared on Corning alumina supports. Measurement of O/sub 2/ chemisorption and BET surface area has been made on a series of Co/Mo/Al/sub 2/O/sub 3/ catalysts obtained from PETC. The catalysts were derived from Cyanamid 1442A and had been tested for coal liquefaction in batch autoclaves and continuous flow units. MoO/sub 3/-Al/sub 2/O/sub 3/ catalysts over the loading range 3.9 to 14.9 wt % MoO/sub 3/ have been studied with respect to BET surface (before and after reduction), O/sub 2/ chemisorption at -78/sup 0/C, redox behavior at 500/sup 0/C, and activity for cyclohexane dehydrogenation at 500/sup 0/C. In connection with the fate of tin catalysts during coal liquefaction, calculations have been made of the relative thermodynamic stability of SnCl/sub 2/, Sn, SnO/sub 2/, and SnS in the presence of H/sub 2/, HCl, H/sub 2/S and H/sub 2/O. Ferrous sulfate dispersed in methylnaphthalene has been shown to be reduced to ferrous sulfide under typical coal hydroliquefaction conditions (1 hour, 450/sup 0/C, 1000 psi initial p/sub H/sub 2//). This suggests that ferrous sulfide may be the common catalytic ingredient when either (a) ferrous sulfate impregnated on powdered coal, or (b) finely divided iron pyrite is used as the catalyst. Old research on impregnated ferrous sulfate, impregnated ferrous halides, and pyrite is consistent with this assumption. Eight Co/Mo/Al/sub 2/O/sub 3/ catalysts from commercial suppliers, along with SnCl/sub 2/, have been studied for the hydrotreating of 1-methylnaphthalene (1-MN) in a stirred autoclave at 450 and 500/sup 0/C.

  5. 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.

  6. Examination of surface phenomena of V₂O₅ loaded on new nanostructured TiO₂ prepared by chemical vapor condensation for enhanced NH₃-based selective catalytic reduction (SCR) at low temperatures.

    Science.gov (United States)

    Cha, Woojoon; Yun, Seong-Taek; Jurng, Jongsoo

    2014-09-01

    In this article, we describe the investigation and surface characterization of a chemical vapor condensation (CVC)-TiO2 support material used in a V2O5/TiO2 catalyst for enhanced selective catalytic reduction (SCR) activity and confirm the mechanism of surface reactions. On the basis of previous studies and comparison with a commercial TiO2 catalyst, we examine four fundamental questions: first, the reason for increased surface V(4+) ion concentrations; second, the origin of the increase in surface acid sites; third, a basis for synergistic influences on improvements in SCR activity; and fourth, a reason for improved catalytic activity at low reaction temperatures. In this study, we have cited the result of SCR with NH3 activity for removing NOx and analyzed data using the reported result and data from previous studies on V2O5/CVC-TiO2 for the SCR catalyst. In order to determine the properties of suitable CVC-TiO2 surfaces for efficient SCR catalysis at low temperatures, CVC-TiO2 specimens were prepared and characterized using techniques such as XRD, BET, HR-TEM, XPS, FT-IR, NH3-TPD, photoluminescence (PL) spectroscopy, H2-TPR, and cyclic voltammetry. The results obtained for the CVC-TiO2 materials were also compared with those of commercial TiO2.

  7. Atomically Precise Metal Nanoclusters for Catalytic Application

    Energy Technology Data Exchange (ETDEWEB)

    Jin, Rongchao [Carnegie Mellon Univ., Pittsburgh, PA (United States)

    2016-11-18

    The central goal of this project is to explore the catalytic application of atomically precise gold nanoclusters. By solving the total structures of ligand-protected nanoclusters, we aim to correlate the catalytic properties of metal nanoclusters with their atomic/electronic structures. Such correlation unravel some fundamental aspects of nanocatalysis, such as the nature of particle size effect, origin of catalytic selectivity, particle-support interactions, the identification of catalytically active centers, etc. The well-defined nanocluster catalysts mediate the knowledge gap between single crystal model catalysts and real-world conventional nanocatalysts. These nanoclusters also hold great promise in catalyzing certain types of reactions with extraordinarily high selectivity. These aims are in line with the overall goals of the catalytic science and technology of DOE and advance the BES mission “to support fundamental research to understand, predict, and ultimately control matter and energy at the level of electrons, atoms, and molecules”. Our group has successfully prepared different sized, robust gold nanoclusters protected by thiolates, such as Au25(SR)18, Au28(SR)20, Au38(SR)24, Au99(SR)42, Au144(SR)60, etc. Some of these nanoclusters have been crystallographically characterized through X-ray crystallography. These ultrasmall nanoclusters (< 2 nm diameter) exhibit discrete electronic structures due to quantum size effect, as opposed to quasicontinuous band structure of conventional metal nanoparticles or bulk metals. The available atomic structures (metal core plus surface ligands) of nanoclusters serve as the basis for structure-property correlations. We have investigated the unique catalytic properties of nanoclusters (i.e. not observed in conventional nanogold catalysts) and revealed the structure-selectivity relationships. Highlights of our

  8. A novel liquid system of catalytic hydrogenation

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

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

  9. Catalytic Combustor for Fuel-Flexible Turbine

    Energy Technology Data Exchange (ETDEWEB)

    Laster, W. R.; Anoshkina, E.

    2008-01-31

    Under the sponsorship of the U. S. Department of Energy’s National Energy Technology Laboratory, Siemens Westinghouse has conducted a three-year program to develop an ultra low NOx, fuel flexible catalytic combustor for gas turbine application in IGCC. The program is defined in three phases: Phase 1- Implementation Plan, Phase 2- Validation Testing and Phase 3 – Field Testing. Both Phase 1 and Phase 2 of the program have been completed. In IGCC power plants, the gas turbine must be capable of operating on syngas as a primary fuel and an available back-up fuel such as natural gas. In this program the Rich Catalytic Lean (RCLTM) technology is being developed as an ultra low NOx combustor. In this concept, ultra low NOx is achieved by stabilizing a lean premix combustion process by using a catalytic reactor to oxidize a portion of the fuel, increasing the temperature of fuel/air mixture prior to the main combustion zone. In Phase 1, the feasibility of the catalytic concept for syngas application has been evaluated and the key technology issues identified. In Phase II the technology necessary for the application of the catalytic concept to IGCC fuels was developed through detailed design and subscale testing. Phase III (currently not funded) will consist of full-scale combustor basket testing on natural gas and syngas.

  10. Catalytic Combustor for Fuel-Flexible Turbine

    Energy Technology Data Exchange (ETDEWEB)

    W. R. Laster; E. Anoshkina

    2008-01-31

    Under the sponsorship of the U. S. Department of Energy's National Energy Technology Laboratory, Siemens Westinghouse has conducted a three-year program to develop an ultra low NOx, fuel flexible catalytic combustor for gas turbine application in IGCC. The program is defined in three phases: Phase 1 - Implementation Plan, Phase 2 - Validation Testing and Phase 3 - Field Testing. Both Phase 1 and Phase 2 of the program have been completed. In IGCC power plants, the gas turbine must be capable of operating on syngas as a primary fuel and an available back-up fuel such as natural gas. In this program the Rich Catalytic Lean (RCLTM) technology is being developed as an ultra low NOx combustor. In this concept, ultra low NOx is achieved by stabilizing a lean premix combustion process by using a catalytic reactor to oxidize a portion of the fuel, increasing the temperature of fuel/air mixture prior to the main combustion zone. In Phase 1, the feasibility of the catalytic concept for syngas application has been evaluated and the key technology issues identified. In Phase II the technology necessary for the application of the catalytic concept to IGCC fuels was developed through detailed design and subscale testing. Phase III (currently not funded) will consist of full-scale combustor basket testing on natural gas and syngas.

  11. A mesoporous catalytic membrane architecture for lithium-oxygen battery systems.

    Science.gov (United States)

    Ryu, Won-Hee; Gittleson, Forrest S; Schwab, Mark; Goh, Tenghooi; Taylor, André D

    2015-01-14

    Controlling the mesoscale geometric configuration of catalysts on the oxygen electrode is an effective strategy to achieve high reversibility and efficiency in Li-O2 batteries. Here we introduce a new Li-O2 cell architecture that employs a catalytic polymer-based membrane between the oxygen electrode and the separator. The catalytic membrane was prepared by immobilization of Pd nanoparticles on a polyacrylonitrile (PAN) nanofiber membrane and is adjacent to a carbon nanotube electrode loaded with Ru nanoparticles. During oxide product formation, the insulating PAN polymer scaffold restricts direct electron transfer to the Pd catalyst particles and prevents the direct blockage of Pd catalytic sites. The modified Li-O2 battery with a catalytic membrane showed a stable cyclability for 60 cycles with a capacity of 1000 mAh/g and a reduced degree of polarization (∼ 0.3 V) compared to cells without a catalytic membrane. We demonstrate the effects of a catalytic membrane on the reaction characteristics associated with morphological and structural features of the discharge products via detailed ex situ characterization.

  12. Catalytic Oxidation of Methane into Methanol over Copper-Exchanged Zeolites with Oxygen at Low Temperature.

    Science.gov (United States)

    Narsimhan, Karthik; Iyoki, Kenta; Dinh, Kimberly; Román-Leshkov, Yuriy

    2016-06-22

    The direct catalytic conversion of methane to liquid oxygenated compounds, such as methanol or dimethyl ether, at low temperature using molecular oxygen is a grand challenge in C-H activation that has never been met with synthetic, heterogeneous catalysts. We report the first demonstration of direct, catalytic oxidation of methane into methanol with molecular oxygen over copper-exchanged zeolites at low reaction temperatures (483-498 K). Reaction kinetics studies show sustained catalytic activity and high selectivity for a variety of commercially available zeolite topologies under mild conditions (e.g., 483 K and atmospheric pressure). Transient and steady state measurements with isotopically labeled molecules confirm catalytic turnover. The catalytic rates and apparent activation energies are affected by the zeolite topology, with caged-based zeolites (e.g., Cu-SSZ-13) showing the highest rates. Although the reaction rates are low, the discovery of catalytic sites in copper-exchanged zeolites will accelerate the development of strategies to directly oxidize methane into methanol under mild conditions.

  13. Catalytic partial oxidation of pyrolysis oils

    Science.gov (United States)

    Rennard, David Carl

    2009-12-01

    This thesis explores the catalytic partial oxidation (CPO) of pyrolysis oils to syngas and chemicals. First, an exploration of model compounds and their chemistries under CPO conditions is considered. Then CPO experiments of raw pyrolysis oils are detailed. Finally, plans for future development in this field are discussed. In Chapter 2, organic acids such as propionic acid and lactic acid are oxidized to syngas over Pt catalysts. Equilibrium production of syngas can be achieved over Rh-Ce catalysts; alternatively mechanistic evidence is derived using Pt catalysts in a fuel rich mixture. These experiments show that organic acids, present in pyrolysis oils up to 25%, can undergo CPO to syngas or for the production of chemicals. As the fossil fuels industry also provides organic chemicals such as monomers for plastics, the possibility of deriving such species from pyrolysis oils allows for a greater application of the CPO of biomass. However, chemical production is highly dependent on the originating molecular species. As bio oil comprises up to 400 chemicals, it is essential to understand how difficult it would be to develop a pure product stream. Chapter 3 continues the experimentation from Chapter 2, exploring the CPO of another organic functionality: the ester group. These experiments demonstrate that equilibrium syngas production is possible for esters as well as acids in autothermal operation with contact times as low as tau = 10 ms over Rh-based catalysts. Conversion for these experiments and those with organic acids is >98%, demonstrating the high reactivity of oxygenated compounds on noble metal catalysts. Under CPO conditions, esters decompose in a predictable manner: over Pt and with high fuel to oxygen, non-equilibrium products show a similarity to those from related acids. A mechanism is proposed in which ethyl esters thermally decompose to ethylene and an acid, which decarbonylates homogeneously, driven by heat produced at the catalyst surface. Chapter 4

  14. PINGU: PredIction of eNzyme catalytic residues usinG seqUence information.

    Directory of Open Access Journals (Sweden)

    Priyadarshini P Pai

    Full Text Available Identification of catalytic residues can help unveil interesting attributes of enzyme function for various therapeutic and industrial applications. Based on their biochemical roles, the number of catalytic residues and sequence lengths of enzymes vary. This article describes a prediction approach (PINGU for such a scenario. It uses models trained using physicochemical properties and evolutionary information of 650 non-redundant enzymes (2136 catalytic residues in a support vector machines architecture. Independent testing on 200 non-redundant enzymes (683 catalytic residues in predefined prediction settings, i.e., with non-catalytic per catalytic residue ranging from 1 to 30, suggested that the prediction approach was highly sensitive and specific, i.e., 80% or above, over the incremental challenges. To learn more about the discriminatory power of PINGU in real scenarios, where the prediction challenge is variable and susceptible to high false positives, the best model from independent testing was used on 60 diverse enzymes. Results suggested that PINGU was able to identify most catalytic residues and non-catalytic residues properly with 80% or above accuracy, sensitivity and specificity. The effect of false positives on precision was addressed in this study by application of predicted ligand-binding residue information as a post-processing filter. An overall improvement of 20% in F-measure and 0.138 in Correlation Coefficient with 16% enhanced precision could be achieved. On account of its encouraging performance, PINGU is hoped to have eventual applications in boosting enzyme engineering and novel drug discovery.

  15. Electro Catalytic Oxidation (ECO) Operation

    Energy Technology Data Exchange (ETDEWEB)

    Morgan Jones

    2011-03-31

    The power industry in the United States is faced with meeting many new regulations to reduce a number of air pollutants including sulfur dioxide, nitrogen oxides, fine particulate matter, and mercury. With over 1,000 power plants in the US, this is a daunting task. In some cases, traditional pollution control technologies such as wet scrubbers and SCRs are not feasible. Powerspan's Electro-Catalytic Oxidation, or ECO{reg_sign} process combines four pollution control devices into a single integrated system that can be installed after a power plant's particulate control device. Besides achieving major reductions in emissions of sulfur dioxide (SO{sub 2}), nitrogen oxides (NOx), fine particulate matter (PM2.5) and mercury (Hg), ECO produces a highly marketable fertilizer, which can help offset the operating costs of the process system. Powerspan has been operating a 50-MW ECO commercial demonstration unit (CDU) at FirstEnergy Corp.'s R.E. Burger Plant near Shadyside, Ohio, since February 2004. In addition to the CDU, a test loop has been constructed beside the CDU to demonstrate higher NOx removal rates and test various scrubber packing types and wet ESP configurations. Furthermore, Powerspan has developed the ECO{reg_sign}{sub 2} technology, a regenerative process that uses a proprietary solvent to capture CO{sub 2} from flue gas. The CO{sub 2} capture takes place after the capture of NOx, SO{sub 2}, mercury, and fine particulate matter. Once the CO{sub 2} is captured, the proprietary solution is regenerated to release CO{sub 2} in a form that is ready for geological storage or beneficial use. Pilot scale testing of ECO{sub 2} began in early 2009 at FirstEnergy's Burger Plant. The ECO{sub 2} pilot unit is designed to process a 1-MW flue gas stream and produce 20 tons of CO{sub 2} per day, achieving a 90% CO{sub 2} capture rate. The ECO{sub 2} pilot program provided the opportunity to confirm process design and cost estimates, and prepare for large

  16. Catalytic microreactors for portable power generation

    Energy Technology Data Exchange (ETDEWEB)

    Karagiannidis, Symeon [Paul Scherer Institute, Villigen (Switzerland)

    2011-07-01

    ''Catalytic Microreactors for Portable Power Generation'' addresses a problem of high relevance and increased complexity in energy technology. This thesis outlines an investigation into catalytic and gas-phase combustion characteristics in channel-flow, platinum-coated microreactors. The emphasis of the study is on microreactor/microturbine concepts for portable power generation and the fuels of interest are methane and propane. The author carefully describes numerical and experimental techniques, providing a new insight into the complex interactions between chemical kinetics and molecular transport processes, as well as giving the first detailed report of hetero-/homogeneous chemical reaction mechanisms for catalytic propane combustion. The outcome of this work will be widely applied to the industrial design of micro- and mesoscale combustors. (orig.)

  17. Catalytic nanoarchitectonics for environmentally compatible energy generation

    Directory of Open Access Journals (Sweden)

    Hideki Abe

    2016-01-01

    Full Text Available Environmentally compatible energy management is one of the biggest challenges of the 21st century. Low-temperature conversion of chemical to electrical energy is of particular importance to minimize the impact to the environment while sustaining the consumptive economy. In this review, we shed light on one of the most versatile energy-conversion technologies: heterogeneous catalysts. We establish the integrity of structural tailoring in heterogeneous catalysts at different scales in the context of an emerging paradigm in materials science: catalytic nanoarchitectonics. Fundamental backgrounds of energy-conversion catalysis are first provided together with a perspective through state-of-the-art energy-conversion catalysis including catalytic exhaust remediation, fuel-cell electrocatalysis and photosynthesis of solar fuels. Finally, the future evolution of catalytic nanoarchitectonics is overviewed: possible combinations of heterogeneous catalysts, organic molecules and even enzymes to realize reaction-selective, highly efficient and long-life energy conversion technologies which will meet the challenge we face.

  18. Gene targeting of CK2 catalytic subunits

    Science.gov (United States)

    Lou, David Y.; Toselli, Paul; Landesman-Bollag, Esther; Dominguez, Isabel

    2013-01-01

    Protein kinase CK2 is a highly conserved and ubiquitous serine–threonine kinase. It is a tetrameric enzyme that is made up of two regulatory CK2β subunits and two catalytic subunits, either CK2α/CK2α, CK2α/ CK2α′, or CK2α′/CK2α′. Although the two catalytic subunits diverge in their C termini, their enzymatic activities are similar. To identify the specific function of the two catalytic subunits in development, we have deleted them individually from the mouse genome by homologous recombination. We have previously reported that CK2α′is essential for male germ cell development, and we now demonstrate that CK2α has an essential role in embryogenesis, as mice lacking CK2α die in mid-embryogenesis, with cardiac and neural tube defects. PMID:18594950

  19. Reactivity of organic compounds in catalytic synthesis

    Energy Technology Data Exchange (ETDEWEB)

    Minachev, Kh.M.; Bragin, O.V.

    1978-01-01

    A comprehensive review of 1976 Soviet research on catalysis delivered to the 1977 annual session of the USSR Academy of Science Council on Catalysis (Baku 6/16-20/77) covers hydrocarbon reactions, including hydrogenation and hydrogenolysis, dehydrogenation, olefin dimerization and disproportionation, and cyclization and dehydrocyclization (e.g., piperylene cyclization and ethylene cyclotrimerization); catalytic and physicochemical properties of zeolites, including cracking, dehydrogenation, and hydroisomerization catalytic syntheses and conversion of heterocyclic and functional hydrocarbon derivatives, including partial and total oxidation (e.g., of o-xylene to phthalic anhydride); syntheses of thiophenes from alkanes and hydrogen sulfide over certain dehydrogenation catalysts; catalytic syntheses involving carbon oxides ( e.g., the development of a new heterogeneous catalyst for hydroformylation of olefins), and of Co-MgO zeolitic catalysts for synthesis of aliphatic hydrocarbons from carbon dioxide and hydrogen, and fabrication of high-viscosity lubricating oils over bifunctional aluminosilicate catalysts.

  20. Catalytic Organic Transformations Mediated by Actinide Complexes

    Directory of Open Access Journals (Sweden)

    Isabell S. R. Karmel

    2015-10-01

    Full Text Available This review article presents the development of organoactinides and actinide coordination complexes as catalysts for homogeneous organic transformations. This chapter introduces the basic principles of actinide catalysis and deals with the historic development of actinide complexes in catalytic processes. The application of organoactinides in homogeneous catalysis is exemplified in the hydroelementation reactions, such as the hydroamination, hydrosilylation, hydroalkoxylation and hydrothiolation of alkynes. Additionally, the use of actinide coordination complexes for the catalytic polymerization of α-olefins and the ring opening polymerization of cyclic esters is presented. The last part of this review article highlights novel catalytic transformations mediated by actinide compounds and gives an outlook to the further potential of this field.

  1. Gene targeting of CK2 catalytic subunits.

    Science.gov (United States)

    Seldin, David C; Lou, David Y; Toselli, Paul; Landesman-Bollag, Esther; Dominguez, Isabel

    2008-09-01

    Protein kinase CK2 is a highly conserved and ubiquitous serine-threonine kinase. It is a tetrameric enzyme that is made up of two regulatory CK2beta subunits and two catalytic subunits, either CK2alpha/CK2alpha, CK2alpha/CK2alpha', or CK2alpha'/CK2alpha'. Although the two catalytic subunits diverge in their C termini, their enzymatic activities are similar. To identify the specific function of the two catalytic subunits in development, we have deleted them individually from the mouse genome by homologous recombination. We have previously reported that CK2alpha' is essential for male germ cell development, and we now demonstrate that CK2alpha has an essential role in embryogenesis, as mice lacking CK2alpha die in mid-embryogenesis, with cardiac and neural tube defects.

  2. Highly Dense Isolated Metal Atom Catalytic Sites

    DEFF Research Database (Denmark)

    Chen, Yaxin; Kasama, Takeshi; Huang, Zhiwei

    2015-01-01

    Atomically dispersed noble-metal catalysts with highly dense active sites are promising materials with which to maximise metal efficiency and to enhance catalytic performance; however, their fabrication remains challenging because metal atoms are prone to sintering, especially at a high metal...... loading. A dynamic process of formation of isolated metal atom catalytic sites on the surface of the support, which was achieved starting from silver nanoparticles by using a thermal surface-mediated diffusion method, was observed directly by using in situ electron microscopy and in situ synchrotron X......-ray diffraction. A combination of electron microscopy images with X-ray absorption spectra demonstrated that the silver atoms were anchored on five-fold oxygen-terminated cavities on the surface of the support to form highly dense isolated metal active sites, leading to excellent reactivity in catalytic oxidation...

  3. Discussion of risks of platinum resources based on a function orientated criticality assessment. Shown by cytostatic drugs and automotive catalytic converters; Diskussion der Risiken der Ressource Platin auf Basis eines um funktionale Faktoren erweiterten Kritikalitaetsassessments. Dargestellt am Beispiel platinhaltiger Zytostatika und Autoabgaskatalysatoren

    Energy Technology Data Exchange (ETDEWEB)

    Thorenz, Andrea; Reller, Armin [University of Augsburg, Chair of Resource Strategy, Environment Science Center, Augsburg (Germany)

    2011-12-15

    The purpose of the study is the enhancement of criticality assessments for resources in order to address function specific factors like dissipation, recycling, bio-activity and toxicity. The developed methodology is applied to platinum-containing cytostatic drugs and automotive catalytic converters. Methods: The study is methodically based on an analysis of resource specific factors like exploration rates, reserves-to-production ratio and regional distribution of exploration areas as well as on the investigation of product/functional depending factors like recycling rates, dissipation rates, bio-diversity and toxicity. Taking into account that economic and ecological risks may occur at any stage of the supply, consumption and dissipation processes, the whole life cycles of the two analyzed products (cytostatic drugs and automotive catalytic converters) are considered. As an approach to reduce potential economic and ecological risks the study is especially focused on recycling strategies. In order to get a better understanding of platinum as an essential resource for the development of our society the history and the cultural impact of the term ''resource'' are introduced. The availability of platinum is crucial for several products of our modern society. Areas of application are e.g. jewellery, automotive catalytic converters, investments (coins, bars), computers, mobile devices, fertilizers and cytostatic drugs. Economic risks are caused by limited sources and dynamic demand of new application areas like fuel cells and drugs. Platinum-containing drugs are used for the treatment of several kinds of cancer such as testicular, breast, colon and prostate. Currently the pharmaceutical industry requires 6,9 tons per year (3 percent of the total demand of platinum). Due to the improvement of medical standards and the ageing society, especially in developing countries, the demand of platinum-containing drugs will rise significantly. The dissipation of

  4. Thermal and catalytic pyrolysis of plastic waste

    Directory of Open Access Journals (Sweden)

    Débora Almeida

    2016-02-01

    Full Text Available Abstract The amount of plastic waste is growing every year and with that comes an environmental concern regarding this problem. Pyrolysis as a tertiary recycling process is presented as a solution. Pyrolysis can be thermal or catalytical and can be performed under different experimental conditions. These conditions affect the type and amount of product obtained. With the pyrolysis process, products can be obtained with high added value, such as fuel oils and feedstock for new products. Zeolites can be used as catalysts in catalytic pyrolysis and influence the final products obtained.

  5. Catalytic gasification of oil-shales

    Energy Technology Data Exchange (ETDEWEB)

    Lapidus, A.; Avakyan, T. [I.M. Gubkin Russian State Univ. of Oil and Gas, Moscow (Russian Federation); Strizhakova, Yu. [Samara State Univ. (Russian Federation)

    2012-07-01

    Nowadays, the problem of complex usage of solid fossil fuels as raw materials for obtaining of motor fuels and chemical products is becoming increasingly important. A one of possible solutions of the problem is their gasification with further processing of gaseous and liquid products. In this work we have investigated the process of thermal and catalytic gasification of Baltic and Kashpir oil-shales. We have shown that, as compared with non-catalytic process, using of nickel catalyst in the reaction increases the yield of gas, as well as hydrogen content in it, and decreases the amount of liquid products. (orig.)

  6. Heterogeneous Catalytic Ozonization of Sulfosalicylic Acid

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    This paper describes the potential of heterogeneous catalytic ozonization of sulfo-salicylic acid (SSal). It was found that catalytic ozonization in the presence of Mn-Zr-O (a modified manganese dioxide supported on silica gel) had significantly enhanced the removal rate (72%) of total organic carbon (TOC) compared with that of ozonization alone (19%). The efficient removal rate of TOC was probably due to increasing the adsorption ability of catalyst and accelerating decomposition of ozone to produce more powerful oxidants than ozone.

  7. 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

    International audience; 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 configur...

  8. Preparation and characterization of nano-CaO based on eggshell waste:Novel and green catalytic approach to highly efficient synthesis of pyrano[4,3-b]pyrans

    Institute of Scientific and Technical Information of China (English)

    Elaheh Mosaddegh; Asadollah Hassankhani

    2014-01-01

    Nano-CaO was prepared by calcination of ball-milled chicken eggshell waste. This novel, bioactive, heterogeneous catalyst, which had high catalytic activity and reusability, was used in the green synthesis of pyrano[4,3-b]pyrans via condensation of various aromatic aldehydes, malononitrile, and 4-hydroxy-6-methyl-2H-pyran-2-one at 120 °C under solvent-free conditions. The reaction proceeded to completion within 5-45 min in 93%-98% yield. The nano-CaO was fully characterized by scanning electron microscopy, X-ray powder diffraction, infrared spectroscopy, X-ray fluores-cence spectroscopy, and thermal gravimetric, surface area, and elemental analyses.

  9. Catalytic performance of symmetrical and unsymmetrical sulfur-containing pincer complexes: synthesis and tandem catalytic activity of the first PCS-pincer palladium complex

    NARCIS (Netherlands)

    Gagliardo, M.; Selander, N.; Mehendale, N.C.; van Koten, G.; Klein Gebbink, R.J.M.; Szabó, K.J.

    2008-01-01

    The synthesis and catalytic applications of a new aryl-based unsymmetrical PCS-pincer complex are reported. Preparation of the robust air- and moisture-stable PCS-pincer palladium complex 5[X] started from the symmetrical ,-dibromo-meta-xylene and involved the selective substitution of one bromide b

  10. Catalytic synthesis of long-chained alcohols from syngas

    DEFF Research Database (Denmark)

    Christensen, Jakob Munkholt

    This work has been an investigation of the catalytic conversion of syngas into mixed alcohols with Mo-based catalysts. The primary focus has been on the use of alkali promoted cobalt-molybdenum sulfide as a catalyst for the alcohol synthesis. The alcohol synthesis is a possibility...... the user to employ a less thorough and therefore less costly syngas cleaning. To evaluate, to which extent a removal of other components in the raw syngas is necessary, the influence of NH3 and H2O in the feed has also been investigated. Ammonia (741 ppmv) in the feed is observed to cause a general...

  11. Immunologically driven chemical engineering of antibodies for catalytic activity.

    Science.gov (United States)

    Dias, Sonia; Jovic, Florence; Renard, Pierre-Yves; Taran, Fréderic; Créminon, Christophe; Mioskowski, Charles; Grassi, Jacques

    2002-11-01

    We describe a new strategy for the preparation of catalytic antibodies based on a two-step procedure. Firstly, monoclonal antibodies are selected only if displaying the following binding features: binding both the substrate and a reactive group in such a way that the two groups are in a reactive position towards each other. Secondly, the selected monoclonal antibodies (mAbs) are chemically engineered by covalently binding the reactive group into the binding pocket of the antibody. Using previously isolated monoclonal antibodies, we have focused our studies on the control of this second step.

  12. 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...... understanding of the nature of the electrochemical promotion is also presented....

  13. Shungite carbon catalytic effect on coal treatment

    Energy Technology Data Exchange (ETDEWEB)

    Grigorieva, E.N.; Rozhkova, N.N. [Russian Academy of Sciences, Moscow (Russian Federation). Institute for High Temperature

    1999-07-01

    The catalytic ability of shungite carbon in reactions of coal organic matter models appeared to be due to its fullerene structure only. Transition metal sulphides present in shungite carbon are not active in the conditions of coal treatment. Shungite carbon was shown to exhibit an acceleration of thermolysis of coal and organic matter models, mainly dehydrogenation. 5 refs., 1 tabs.

  14. Catalytic site interactions in yeast OMP synthase

    DEFF Research Database (Denmark)

    Hansen, Michael Riis; Barr, Eric W.; Jensen, Kaj Frank;

    2014-01-01

    45 (2006) 5330-5342]. This behavior was investigated in the yeast enzyme by mutations in the conserved catalytic loop and 5-phosphoribosyl-1-diphosphate (PRPP) binding motif. Although the reaction is mechanistically sequential, the wild-type (WT) enzyme shows parallel lines in double reciprocal...

  15. Catalytic Amination of Alcohols, Aldehydes, and Ketones

    Science.gov (United States)

    Klyuev, M. V.; Khidekel', M. L.

    1980-01-01

    Data on the catalytic amination of alcohols and carbonyl compounds are examined, the catalysts for these processes are described, and the problems of their effectiveness, selectivity, and stability are discussed. The possible mechanisms of the reactions indicated are presented. The bibliography includes 266 references.

  16. Catalytic Asymmetric Synthesis of Phosphine Boronates.

    Science.gov (United States)

    Hornillos, Valentín; Vila, Carlos; Otten, Edwin; Feringa, Ben L

    2015-06-26

    The first catalytic enantioselective synthesis of ambiphilic phosphine boronate esters is presented. The asymmetric boration of α,β-unsaturated phosphine oxides catalyzed by a copper bisphosphine complex affords optically active organoboronate esters that bear a vicinal phosphine oxide group in good yields and high enantiomeric excess. The synthetic utility of the products is demonstrated through stereospecific transformations into multifunctional optically active compounds.

  17. SELECTIVE CATALYTIC REDUCTION MERCURY FIELD SAMPLING PROJECT

    Science.gov (United States)

    A lack of data still exists as to the effect of selective catalytic reduction (SCR), selective noncatalytic reduction (SNCR), and flue gas conditioning on the speciation and removal of mercury (Hg) at power plants. This project investigates the impact that SCR, SNCR, and flue gas...

  18. Performance characterization of a hydrogen catalytic heater.

    Energy Technology Data Exchange (ETDEWEB)

    Johnson, Terry Alan; Kanouff, Michael P.

    2010-04-01

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

  19. The Catalytic Asymmetric Intramolecular Stetter Reaction.

    Science.gov (United States)

    de Alaniz, Javier Read; Rovis, Tomislav

    2009-05-01

    This account chronicles our efforts at the development of a catalytic asymmetric Stetter reaction using chiral triazolium salts as small molecule organic catalysts. Advances in the mechanistically related azolium-catalyzed asymmetric benzoin reaction are discussed, particularly as they apply to catalyst design. A chronological treatise of reaction discovery, catalyst optimization and reactivity extension follows.

  20. Selectivity of catalytic methods of determination.

    Science.gov (United States)

    Otto, M; Mueller, H; Werner, G

    1978-03-01

    By means of catalytic analytical methods, extremely low levels can be determined at low cost and with a high sensitivity that is equal to that of physical methods of trace analysis. The selectivity of the catalytic determinations, is, however, usually rather lower than that of other methods of trace analysis. The selectivity can sometimes be improved by modification of the indicator reaction through variation of the reagents and their concentrations, or by use of masking reagents or activators, or by combination with a separation method. Modification of the indicator reaction can be exemplified by the selective determination of osmium and ruthenium by their catalysis of the nitrate oxidation of 1-naphthylamine. By variation of the nitrate concentration and the use of 1,10-phenanthroline and 8-hydroxyquinoline as complexing agents it is possible to determine these two elements simultaneously. An especially significant increase in the selectivity is made possible by use of a preliminary separation step. If the ion to be determined is separated by solvent extraction and then catalytically determined directly in the extract, a very specific determination is possible; this technique has been called "extractive catalytic determination". This method has been used for determination of molybdenum (0.5 ng/ml) in sea-water, iron (5 ng/ml) in heavy metal salts, and copper (3 ng/ml) in the presence of numerous elements.

  1. Micromachined Catalytic Combustible Hydrogen Gas Sensor Based on Nano-structured SnO2%纳米氧化锡修饰的微催化燃烧式氢气传感器的研制

    Institute of Scientific and Technical Information of China (English)

    刘西锋; 董汉鹏; 夏善红

    2013-01-01

    研制了一种基于多孔纳米氧化锡(SnO2)催化剂的微催化燃烧式气体传感芯片(Pellistor).基于微机电系统(MicroElectro-Mechanical Systems,MEMS)工艺制备硅基封闭膜式微催化燃烧式传感器,通过气相沉积技术在Pt微加热电极和高温绝缘层表面制备三维纳米氧化锡催化膜,利用催化膜对氢气良好的催化特性,采用惠斯通电桥电路进行测量,实现对空气环境中氢气在0~4%浓度范围内的快速检测,响应时间和恢复时间分别达到0.65 s和2.32 s,灵敏度达75.4mV/1% H2,线性度为99.4%.考察200天内该传感芯片对氢气的检测能力,传感芯片表现出良好的稳定性,精确度保持在95%以上.在绝缘层高温性能稳定的条件下,将三维纳米氧化锡应用于微催化燃烧式传感器的氢气检测,对催化燃烧式传感器性能的改进具有重要的意义.%A new type of micro catalytic combustible gas sensor system was designed and fabricated using micro-electro mechanical system (MEMS) technology. A chemical vapor deposition (CVD) method is used to coat porous nano-crystalline SnO2 catalyst layer. Tin chloride anhydrate vapor was used as the precursor, and it reacted with ammonium sulfide [(NH4)2S] to form tin disulfide (SnS2) nanoparticles. The tin disulfide was dried up, annealed in air, then it transformed into polycrystal-line SnO2 nanoparticles. The X-ray diffraction (XRD) measurement was used to investigate the structural properties of the SnO2 films. The morphology of the samples was investigated by field-emission scanning electron microscopy (FESEM). X-ray photoelectron spectroscopy (XPS) provided the information on chemical composition of the SnO2 films. The sensing elements and the reference elements were connected to a Wheatstone bridge circuit for the measurement of gas-sensing properties. The catalytic combustion sensor exhibited relatively higher sensitivity (75.4 mV/1% H2) and good linearity (99.4%) to H2 from 0 to 4% V

  2. Surface Modification of Catalytic Materials

    DEFF Research Database (Denmark)

    Nierhoff, Anders Ulrik Fregerslev

    aggregation techniques. With the use of two different filter mechanisms, the Quadrupole and the Lateral Time Of Flight, the nanoparticles were mass selected. This was done to correlate nanoparticle size with reactivity. Selected key findings can be summarized as: 1) CO induced surface changes of Pt based...

  3. Multifunctional rare earth or bismuth oxide materials for catalytic or electrical applications

    Directory of Open Access Journals (Sweden)

    Gavarri J.R.

    2013-09-01

    Full Text Available We present a review on catalytic or electrical properties of materials based on rare earth (RE oxides (CeO2, La2O3, Lu2O3 or bismuth based composite systems CeO2-Bi2O3, susceptible to be integrated into catalytic microsystems or gas sensors. The polycrystalline solids can be used as catalysts allowing conversion of CO or CH4 traces in air-gas flows. Fourier Transform infrared spectroscopy is used to determine the conversion rate of CO or CH4 into CO2 through the variations versus time and temperature of vibrational band intensities. The time dependent reactivities are interpreted in terms of an adapted Avrami model. In these catalytic analyses the nature of surfaces of polycrystalline solids seems to play a prominent role in catalytic efficiency. Electrical impedance spectroscopy allows analyzing the variation of conductivity of the system CeO2-Bi2O3. In this system, the specific high ionic conduction of a Bi2O3 tetragonal phase might be linked to the high catalytic activity.

  4. On the origin of the catalytic power of carboxypeptidase A and other metalloenzymes.

    Science.gov (United States)

    Kilshtain, Alexandra Vardi; Warshel, Arieh

    2009-11-15

    Zinc metalloenzymes play a major role in key biological processes and carboxypeptidase-A (CPA) is a major prototype of such enzymes. The present work quantifies the energetics of the catalytic reaction of CPA and its mutants using the empirical valence bond (EVB) approach. The simulations allow us to quantify the origin of the catalytic power of this enzyme and to examine different mechanistic alternatives. The first step of the analysis used experimental information to determine the activation energy of each assumed mechanism of the reference reaction without the enzyme. The next step of the analysis involved EVB simulations of the reference reaction and then a calibration of the simulations by forcing them to reproduce the energetics of the reference reaction, in each assumed mechanism. The calibrated EVB was then used in systematic simulations of the catalytic reaction in the protein environment, without changing any parameter. The simulations reproduced the observed rate enhancement in two feasible general acid-general base mechanisms (GAGB-1 and GAGB-2), although the calculations with the GAGB-2 mechanism underestimated the catalytic effect in some treatments. We also reproduced the catalytic effect in the R127A mutant. The mutation calculations indicate that the GAGB-2 mechanism is significantly less likely than the GAGB-1 mechanism. It is also found, that the enzyme loses all its catalytic effect without the metal. This and earlier studies show that the catalytic effect of the metal is not some constant electrostatic effect, that can be assessed from gas phase studies, but a reflection of the dielectric effect of the specific environment.

  5. 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.

  6. 复合污泥基活性炭催化臭氧氧化降解水中罗丹明B%The catalytic ozonation of sludge-based composite activated carbon for the degradation of Rh B in aqueous solution

    Institute of Scientific and Technical Information of China (English)

    游洋洋; 卢学强; 许丹宇; 张涛; 石岩; 杨昂

    2015-01-01

    The sludge-based composite activated carbon(CAC) has been prepared,using biological sludge and chemical sludge in a wastewater treatment plant as raw materials ,and compared with pure biological sludge-based activated carbon(BAC),and commercial activated carbon(CA). The removing effect of catalytic ozonation on Rh B in aqueous solution,in the presence of adsorption,catalystic ozonation and free radical inhibitor has been investigat-ed. Furthermore,the effect of the dosages of Rh B in aqueous solution and ozone on CAC catalyzing capacity has been studied. The results show that all of the three kinds of activated carbon can improve the degradation efficiency of Rh B by catalytic oxidation. CAC has the best catalysis efficiency. The reaction of Rh B degradation by CAC catalytic ozonation follows the mechanism of hydroxyl radical. With the increase of pH and ozone dosage ,the CAC catalysis efficiency increases.%以污水处理厂生物污泥和化学污泥等为原料制备出复合污泥基活性炭(CAC),与纯生物污泥基活性炭(BAC)和商品活性炭(AC)对比,分别考察了吸附、催化臭氧氧化和自由基抑制剂存在时催化臭氧氧化对水中罗丹明B的去除效果,进而研究了pH和臭氧投加量对CAC催化效能的影响。结果表明,三种活性炭均能提高臭氧氧化降解罗丹明B的效率,CAC催化效能最好。 CAC催化臭氧氧化罗丹明B的反应遵循羟基自由基机理,随着pH的增大和臭氧投加量增加,CAC催化效能得到提高。

  7. High-Resolution Single-Molecule Fluorescence Imaging of Zeolite Aggregates within Real-Life Fluid Catalytic Cracking Particles**

    Science.gov (United States)

    Ristanović, Zoran; Kerssens, Marleen M; Kubarev, Alexey V; Hendriks, Frank C; Dedecker, Peter; Hofkens, Johan; Roeffaers, Maarten B J; Weckhuysen, Bert M

    2015-01-01

    Fluid catalytic cracking (FCC) is a major process in oil refineries to produce gasoline and base chemicals from crude oil fractions. The spatial distribution and acidity of zeolite aggregates embedded within the 50–150 μm-sized FCC spheres heavily influence their catalytic performance. Single-molecule fluorescence-based imaging methods, namely nanometer accuracy by stochastic chemical reactions (NASCA) and super-resolution optical fluctuation imaging (SOFI) were used to study the catalytic activity of sub-micrometer zeolite ZSM-5 domains within real-life FCC catalyst particles. The formation of fluorescent product molecules taking place at Brønsted acid sites was monitored with single turnover sensitivity and high spatiotemporal resolution, providing detailed insight in dispersion and catalytic activity of zeolite ZSM-5 aggregates. The results point towards substantial differences in turnover frequencies between the zeolite aggregates, revealing significant intraparticle heterogeneities in Brønsted reactivity. PMID:25504139

  8. Synthesis of ceramic catalytic system based on CuO/CeO{sub 2} for preferential oxidation reaction of CO; Sintese de sistemas cataliticos ceramicos de CuO/CeO{sub 2} destinados a reacao de oxidacao preferencial do CO

    Energy Technology Data Exchange (ETDEWEB)

    Neiva, L.S.; Ribeiro, M.A.; Bispo, A.; Gama, L., E-mail: lsoutoneiva@yahoo.com.b [Universidade Federal de Campina Grande (UFCG), PB (Brazil). Unidade Academica de Engenharia de Materiais

    2010-07-01

    The aim this is work is to develop catalysts based on CuO/CeO{sub 2} by means two different types of synthesis methods: combustion synthesis and Pechini. CuO/CeO{sub 2} 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)

  9. Nanocatalysis: size- and shape-dependent chemisorption and catalytic reactivity

    Science.gov (United States)

    Roldan Cuenya, Beatriz; Behafarid, Farzad

    2015-06-01

    In recent years, the field of catalysis has experienced an astonishing transformation, driven in part by more demanding environmental standards and critical societal and industrial needs such as the search for alternative energy sources. Thanks to the advent of nanotechnology, major steps have been made towards the rational design of novel catalysts. Striking new catalytic properties, including greatly enhanced reactivities and selectivities, have been reported for nanoparticle (NP) catalysts as compared to their bulk counterparts. However, in order to harness the power of these nanocatalysts, a detailed understanding of the origin of their enhanced performance is needed. The present review focuses on the role of the NP size and shape on chemisorption and catalytic performance. Since homogeneity in NP size and shape is a prerequisite for the understanding of structure-reactivity correlations, we first review different synthesis methods that result in narrow NP size distributions and shape controlled NPs. Next, size-dependent phenomena which influence the chemical reactivity of NPs, including quantum size-effects and the presence of under-coordinated surface atoms are examined. The effect of the NP shape on catalytic performance is discussed and explained based on the existence of different atomic structures on the NP surface with distinct chemisorption properties. The influence of additional factors, such as the oxidation state of the NPs and NP-support interactions, is also considered in the frame of the size- and shape-dependency that these phenomena present. Ultimately, our review highlights the importance of achieving a systematic understanding of the factors that control the activity and selectivity of a catalyst in order to avoid trial and error methods in the rational design of the new generation of nanocatalysts with properties tunable at the atomic level.

  10. Designing functional metalloproteins: from structural to catalytic metal sites.

    Science.gov (United States)

    Zastrow, Melissa L; Pecoraro, Vincent L

    2013-09-01

    Metalloenzymes efficiently catalyze some of the most important and difficult reactions in nature. For many years, coordination chemists have effectively used small molecule models to understand these systems. More recently, protein design has been shown to be an effective approach for mimicking metal coordination environments. Since the first designed proteins were reported, much success has been seen for incorporating metal sites into proteins and attaining the desired coordination environment but until recently, this has been with a lack of significant catalytic activity. Now there are examples of designed metalloproteins that, although not yet reaching the activity of native enzymes, are considerably closer. In this review, we highlight work leading up to the design of a small metalloprotein containing two metal sites, one for structural stability (HgS3) and the other a separate catalytic zinc site to mimic carbonic anhydrase activity (ZnN3O). The first section will describe previous studies that allowed for a high affinity thiolate site that binds heavy metals in a way that stabilizes three-stranded coiled coils. The second section will examine ways of preparing histidine rich environments that lead to metal based hydrolytic catalysts. We will also discuss other recent examples of the design of structural metal sites and functional metalloenzymes. Our work demonstrates that attaining the proper first coordination geometry of a metal site can lead to a significant fraction of catalytic activity, apparently independent of the type of secondary structure of the surrounding protein environment. We are now in a position to begin to meet the challenge of building a metalloenzyme systematically from the bottom-up by engineering and analyzing interactions directly around the metal site and beyond.

  11. MODIFICATION OF PALLADIUM METALLIC CATALYST WITH POLYMER-ANCHORED THIOETHER LIGANDS

    Institute of Scientific and Technical Information of China (English)

    LIU Hanfan; MAO Guoping

    1993-01-01

    A well-dispersed metallic palladium catalyst modified by polymer-anchored thioether ligands was used for the hydrogenation of cyclopentadiene to cyclopentene with high activity and selectivity in ambient condition. The evidences to show the modification of catalytic properties by polymer anchored ligands were given.

  12. High-Throughput Continuous Flow Synthesis of Nickel Nanoparticles for the Catalytic Hydrodeoxygenation of Guaiacol

    Energy Technology Data Exchange (ETDEWEB)

    Roberts, Emily J.; Habas, Susan E.; Wang, Lu; Ruddy, Daniel A.; White, Erick A.; Baddour, Frederick G.; Griffin, Michael B.; Schaidle, Joshua A.; Malmstadt, Noah; Brutchey, Richard L.

    2016-11-07

    The translation of batch chemistries to high-throughput continuous flow methods dresses scaling, automation, and reproducibility concerns associated with the implementation of colloidally prepared nanoparticle (NP) catalysts for industrial catalytic processes. Nickel NPs were synthesized by the high-temperature amine reduction of a Ni2+ precursor using a continuous millifluidic (mF) flow method, achieving yields greater than 60%. The resulting Ni NP catalysts were compared against catalysts prepared in a batch reaction under conditions analogous to the continuous flow conditions with respect to total reaction volume, time, and temperature and by traditional incipient wetness (IW) impregnation for the hydrodeoxygenation (HDO) of guaiacol under ex situ catalytic fast pyrolysis conditions. Compared to the IW method, the colloidally prepared NPs displayed increased morphological control and narrowed size distributions, and the NPs prepared by both methods showed similar size, shape, and crystallinity. The Ni NP catalyst synthesized by the continuous flow method exhibited similar H-adsorption site densities, site-time yields, and selectivities towards deoxygenated products as compared to the analogous batch reaction, and outperformed the IW catalyst with respect to higher selectivity to lower oxygen content products and a 6.9-fold slower deactivation rate. These results demonstrate the utility of synthesizing colloidal Ni NP catalysts using continuous flow methods while maintaining the catalytic properties displayed by the batch equivalent. This methodology can be extended to other catalytically relevant base metals for the high-throughput synthesis of metal NPs for the catalytic production of biofuels.

  13. 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.

  14. PREPARATION AND CATALYTIC ACTIVITY OF BIOACTIVE FIBERS

    Institute of Scientific and Technical Information of China (English)

    Yu-yuan Yao; Wen-xing Chen; Bao-yan Zhao; Shen-shui Lü

    2006-01-01

    Two kinds of water-soluble metallophthalocyanines, binuclear cobalt phthalocyanine (Co2Pc2) and binuclear ferric phthalocyanine (Fe2Pc2), were synthesized through phenylanhydride-urea route and characterized by elemental analysis and FT-IR spectra. Binuclear metallophthalocyanine derivatives (Mt2Pc2) were immobilized on silk fibers and modified viscose fibers to construct bioactive fibers of mimic enzyme. Mt2Pc2 was used as the active center ofbioactive fibers, viscose and silk fibers as the microenvironments. The catalytic oxidation ability of bioactive fibers on the malodors of methanthiol and hydrogen sulfide was investigated at room temperature. The experimental results indicated that the catalytic activity of such bioactive fibers was closely correlative to the types ofbioactive fibers and substrates.

  15. Janus droplet as a catalytic micromotor

    CERN Document Server

    Shklyaev, Sergey

    2015-01-01

    Self-propulsion of a Janus droplet in a solution of surfactant, which reacts on a half of a drop surface, is studied theoretically. The droplet acts as a catalytic motor creating a concentration gradient, which generates its surface-tension-driven motion; the self-propulsion speed is rather high, $60\\; {\\rm \\mu m/s}$ and more. This catalytic motor has several advantages over other micromotors: simple manufacturing, easily attained neutral buoyancy. In contrast to a single-fluid droplet, which demonstrates a self-propulsion as a result of symmetry breaking instability, for Janus one no stability threshold exists; hence, the droplet radius can be scaled down to micrometers. The paper was finalized and submitted by Denis S. Goldobin after Sergey Sklyaev had sadly passed away on June 2, 2014.

  16. Materials for High-Temperature Catalytic Combustion

    Energy Technology Data Exchange (ETDEWEB)

    Ersson, Anders

    2003-04-01

    Catalytic combustion is an environmentally friendly technique to combust fuels in e.g. gas turbines. Introducing a catalyst into the combustion chamber of a gas turbine allows combustion outside the normal flammability limits. Hence, the adiabatic flame temperature may be lowered below the threshold temperature for thermal NO{sub X} formation while maintaining a stable combustion. However, several challenges are connected to the application of catalytic combustion in gas turbines. The first part of this thesis reviews the use of catalytic combustion in gas turbines. The influence of the fuel has been studied and compared over different catalyst materials. The material section is divided into two parts. The first concerns bimetallic palladium catalysts. These catalysts showed a more stable activity compared to their pure palladium counterparts for methane combustion. This was verified both by using an annular reactor at ambient pressure and a pilot-scale reactor at elevated pressures and flows closely resembling the ones found in a gas turbine combustor. The second part concerns high-temperature materials, which may be used either as active or washcoat materials. A novel group of materials for catalysis, i.e. garnets, has been synthesised and tested in combustion of methane, a low-heating value gas and diesel fuel. The garnets showed some interesting abilities especially for combustion of low-heating value, LHV, gas. Two other materials were also studied, i.e. spinels and hexa aluminates, both showed very promising thermal stability and the substituted hexa aluminates also showed a good catalytic activity. Finally, deactivation of the catalyst materials was studied. In this part the sulphur poisoning of palladium, platinum and the above-mentioned complex metal oxides has been studied for combustion of a LHV gas. Platinum and surprisingly the garnet were least deactivated. Palladium was severely affected for methane combustion while the other washcoat materials were

  17. Selective Catalytic Reduction of NO with Methane

    Institute of Scientific and Technical Information of China (English)

    Xiang Gao; Qi Yu; Limin Chen

    2003-01-01

    The removal of nitrogen oxides from exhaust gases has attracted great attention in recent years, and many approaches have been developed depending on the application. Methane, the main component of natural gas, has great potential as a NO reductant. In this paper, a number of catalysts previous reported for this catalytic reduction of NO have been reviewed, including a direct comparison of the relative activities and effective factors of the catalysts. Reaction mechanisms have also been explored preliminarily.

  18. Zeolitic catalytic conversion of alochols to hydrocarbons

    Energy Technology Data Exchange (ETDEWEB)

    Narula, Chaitanya K.; Davison, Brian H.; Keller, Martin

    2017-01-03

    A method for converting an alcohol to a hydrocarbon, the method comprising contacting said alcohol with a metal-loaded zeolite catalyst at a temperature of at least 100.degree. C. and up to 550.degree. C., wherein said alcohol can be produced by a fermentation process, said metal is a positively-charged metal ion, and said metal-loaded zeolite catalyst is catalytically active for converting said alcohol to said hydrocarbon.

  19. Catalytic fast pyrolysis of lignocellulosic biomass

    Energy Technology Data Exchange (ETDEWEB)

    Liu, Changjun; Wang, Huamin; Karim, Ayman M.; Sun, Junming; Wang, Yong

    2014-11-21

    Increasing energy demand, especially in the transportation sector, and soaring CO2 emissions necessitate the exploitation of renewable sources of energy. Despite the large variety of new energy Q3 carriers, liquid hydrocarbon still appears to be the most attractive and feasible form of transportation fuel taking into account the energy density, stability and existing infrastructure. Biomass is an abundant, renewable source of energy; however, utilizing it in a cost-effective way is still a substantial challenge. Lignocellulose is composed of three major biopolymers, namely cellulose, hemicellulose and lignin. Fast pyrolysis of biomass is recognized as an efficient and feasible process to selectively convert lignocellulose into a liquid fuel—bio-oil. However bio-oil from fast pyrolysis contains a large amount of oxygen, distributed in hundreds of oxygenates. These oxygenates are the cause of many negative properties, such as low heating values, high corrosiveness, high viscosity, and instability; they also greatly Q4 limit the application of bio-oil particularly as transportation fuel. Hydrocarbons derived from biomass are most attractive because of their high energy density and compatibility with the existing infrastructure. Thus, converting lignocellulose into transportation fuels via catalytic fast pyrolysis has attracted much attention. Many studies related to catalytic fast pyrolysis of biomass have been published. The main challenge of this process is the development of active and stable catalysts that can deal with a large variety of decomposition intermediates from lignocellulose. This review starts with the current understanding of the chemistry in fast pyrolysis of lignocellulose and focuses on the development of catalysts in catalytic fast pyrolysis. Recent progress in the experimental studies on catalytic fast pyrolysis of biomass is also summarized with the emphasis on bio-oil yields and quality.

  20. Thermal and catalytic pyrolysis of plastic waste

    OpenAIRE

    Débora Almeida; Maria de Fátima Marques

    2016-01-01

    Abstract The amount of plastic waste is growing every year and with that comes an environmental concern regarding this problem. Pyrolysis as a tertiary recycling process is presented as a solution. Pyrolysis can be thermal or catalytical and can be performed under different experimental conditions. These conditions affect the type and amount of product obtained. With the pyrolysis process, products can be obtained with high added value, such as fuel oils and feedstock for new products. Zeolit...

  1. Catalytic spectrophotometric determination of trace selenium in microemulsion after separation and enrichment by SDG

    Institute of Scientific and Technical Information of China (English)

    LI Huizhi; ZHAI Diantang; FAN Yingju

    2006-01-01

    A new catalytic spectrophotometric method was developed for the determination of trace amount of Se(Ⅳ) in microemulsion medium. The method is based on the catalytic effect of traces of Se(Ⅳ) on the oxidation of2',4'-dichlorophenylfluorone (p-CPF) by potassium bromate with HNO3 as an activator in the presence of nonionic microemulsion medium. Under optimum conditions, the calibration graph is linear in the range of 0.4-15 μg. L-1 of Se(Ⅳ) atseparated and enriched by sulphydryl dextrane gel (SDG). The method has been applied for determination of trace selenium with satisfactory results.

  2. FAILURE ANALYSIS AND INSPECTION OF CRACKING OF IN-SERVICE CATALYTIC REGENERATOR

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    The special subject"research on life prediction technology of important in-service pressure vessels" mainly analyzes the failure mechanism of large-sized important and critical in-service pressure vessels under the action of working medium and investigates safety assessment and life prediction technology with a view to enhance the operation reliability of in-service pressure vessels in China. Based on a series of accident investigation and test & measuring research, the cause of cracking of catalytic regenerator is analyzed and the in-line non-destructive examination method and failure prevention measures for the cracking of catalytic regenerator are proposed.

  3. Catalytic Spectrophotometric Determination of Trace Vanadium Based on Oxidation of Arsenazo Ⅲ with Bichromate by Using Triton X-100 to Enhance Its Effect%重铬酸钾氧化偶氮胂Ⅲ动力学光度法测定痕量硒

    Institute of Scientific and Technical Information of China (English)

    周之荣; 周瑜芬; 李桂艳

    2007-01-01

    A catalytic spectrophotometry for the determination of trace vanadium(Ⅴ) based on its catalytic effect on discoloring reaction of oxidation of arsenazo Ⅲ (AsA Ⅲ) with potassium bichromate in a weak acid medium is described, and the addition of Triton X- 100 can further increase the sensitivity of the reaction and its catalytic extent is linear with the content of V(Ⅴ). The reaction rate is monitored spectrophotometrically by measuring the decrease in absorbance of AsA Ⅲ at 550 nm after a fixed time (8 min). The calibration graph is linear in the range of 0.0~20.0μg/L vanadium (Ⅴ) and the detection limit of the method is 0.15μg/L. Combined with ion-exchange resin separation. The method has been successfully applied to the determination of V(Ⅴ)in food samples with the relative standard deviation of 1.18%~4.00% and the recovery of 97.5%~ 102.5%. The results are in good agreement with those provided by AAS method. The method has also been applied to the determination of V(Ⅴ) in human hair, plant and tea samples, and the results are in agreement with certified values.%基于稀HCl介质中,在非离子表面活性剂Triton X-100存在时,痕量钒(Ⅴ)催化重铬酸钾氧化偶氮胂Ⅲ的褪色反应,建立了测定痕量钒(Ⅴ)的催化动力学光度法.方法检出限为0.15μg/L,线性范围为0.0~20.0μg/L.结合离子交换树脂分离,实现了食品中痕量钒(Ⅴ)的测定,加标回收率为97.5%~102.5%,样品测定的相对标准偏差(RSD)为1.18%~4.00%.用于测定人发、植物、茶叶样品中的痕量钒(Ⅴ),结果满意.

  4. Electrochemistry as a Tool for Study, Delvelopment and Promotion of Catalytic Reactions

    DEFF Research Database (Denmark)

    Petrushina, Irina

    The first two chapters of the dissertation are dedicated to definition of the peculiarities of electrochemical processes and also common features and differences between heterogeneous redox and catalytic reactions and electrochemical reactions. The main common characteristic of heterogeneous...... catalytic reactions and electrochemical reactions is defined. It is the Fermi level of the catalyst, which is also the electrochemical potential of the electrode. According to the Newns-Anderson theory, Fermi level of catalysts affects (or even define) their activity. The electrochemical potential can...... be measured and changed by polarization in electrochemical experiment. In Chapter 3 the nature of the electrochemical heterogeneous catalytic reactions is dicussed, including the new theory of electrochemical promotion. This theory is based on electrochemical change of the Fermi level of the catalyst. It also...

  5. Catalytic ramifications of steam deactivation of Y zeolites: An analysis using 2-methylhexane cracking

    Energy Technology Data Exchange (ETDEWEB)

    Yaluris, G.; Dumesic, J.A. [Univ. of Wisconsin, Madison, WI (United States); Madon, R.J. [Engelhard Corp., Iselin, NJ (United States)

    1999-08-15

    Kinetic analysis of experimental data for 2-methylhexane cracking demonstrates that trends in activity and selectivity are well simulated by adjusting a single parameter that represents the acid strength of a Y-based FCC catalyst. This acid strength may be modified via steam deactivation, and the authors have experimentally corroborated acidity changes using ammonia microcalorimetry and infrared spectroscopy. Increased severity of steam treatment reduces the number and strength of catalyst acid sites, and it leads to a reduction in the turnover frequency of all surface processes and a decrease in overall site time yield. Streaming of the catalyst does not change the fundamental chemistry involved in catalytic cracking. However, change in acidity caused by steaming alters product selectivity by changing relative rates of various catalytic cycles in the cracking process. For example, steam treatment increases olefin selectivity by favoring catalytic cycles that produce olefins.

  6. Liquid-phase chemical hydrogen storage: catalytic hydrogen generation under ambient conditions.

    Science.gov (United States)

    Jiang, Hai-Long; Singh, Sanjay Kumar; Yan, Jun-Min; Zhang, Xin-Bo; Xu, Qiang

    2010-05-25

    There is a demand for a sufficient and sustainable energy supply. Hence, the search for applicable hydrogen storage materials is extremely important owing to the diversified merits of hydrogen energy. Lithium and sodium borohydride, ammonia borane, hydrazine, and formic acid have been extensively investigated as promising hydrogen storage materials based on their relatively high hydrogen content. Significant advances, such as hydrogen generation temperatures and reaction kinetics, have been made in the catalytic hydrolysis of aqueous lithium and sodium borohydride and ammonia borane as well as in the catalytic decomposition of hydrous hydrazine and formic acid. In this Minireview we briefly survey the research progresses in catalytic hydrogen generation from these liquid-phase chemical hydrogen storage materials.

  7. Catalytic pyrolysis of olive mill wastewater sludge

    Science.gov (United States)

    Abdellaoui, Hamza

    From 2008 to 2013, an average of 2,821.4 kilotons/year of olive oil were produced around the world. The waste product of the olive mill industry consists of solid residue (pomace) and wastewater (OMW). Annually, around 30 million m3 of OMW are produced in the Mediterranean area, 700,000 m3 year?1 in Tunisia alone. OMW is an aqueous effluent characterized by an offensive smell and high organic matter content, including high molecular weight phenolic compounds and long-chain fatty acids. These compounds are highly toxic to micro-organisms and plants, which makes the OMW a serious threat to the environment if not managed properly. The OMW is disposed of in open air evaporation ponds. After evaporation of most of the water, OMWS is left in the bottom of the ponds. In this thesis, the effort has been made to evaluate the catalytic pyrolysis process as a technology to valorize the OMWS. The first section of this research showed that 41.12 wt. % of the OMWS is mostly lipids, which are a good source of energy. The second section proved that catalytic pyrolysis of the OMWS over red mud and HZSM-5 can produce green diesel, and 450 °C is the optimal reaction temperature to maximize the organic yields. The last section revealed that the HSF was behind the good fuel-like properties of the OMWS catalytic oils, whereas the SR hindered the bio-oil yields and quality.

  8. Studies of catalytic coal gasification with steam

    Directory of Open Access Journals (Sweden)

    Porada Stanisław

    2016-09-01

    Full Text Available One of the promising processes, belonging to the so-called clean coal technologies, is catalytic coal gasification. The addition of a catalyst results in an increased process rate, in which synthesis gas is obtained. Therefore, the subject of this research was catalytic gasification of low-ranking coal which, due to a high reactivity, meets the requirements for fuels used in the gasification process. Potassium and calcium cations in an amount of 0.85, 1.7 and 3.4% by weight were used as catalytically active substances. Isothermal measurements were performed at 900°C under a pressure of 2 MPa using steam as a gasifying agent. On the basis of kinetic curves, the performance of main gasification products as well as carbon conversion degree were determined. The performed measurements allowed the determination of the type and amount of catalyst that ensure the most efficient gasification process of the coal ‘Piast’ in an atmosphere of steam.

  9. A revolution in micropower : the catalytic nanodiode.

    Energy Technology Data Exchange (ETDEWEB)

    Cross, Karen Charlene; Heller, Edwin J.; Figiel, Jeffrey James; Coker, Eric Nicholas; Creighton, James Randall; Koleske, Daniel David; Bogart, Katherine Huderle Andersen; Coltrin, Michael Elliott; Pawlowski, Roger Patrick; Baucom, Kevin C.

    2010-11-01

    Our ability to field useful, nano-enabled microsystems that capitalize on recent advances in sensor technology is severely limited by the energy density of available power sources. The catalytic nanodiode (reported by Somorjai's group at Berkeley in 2005) was potentially an alternative revolutionary source of micropower. Their first reports claimed that a sizable fraction of the chemical energy may be harvested via hot electrons (a 'chemicurrent') that are created by the catalytic chemical reaction. We fabricated and tested Pt/GaN nanodiodes, which eventually produced currents up to several microamps. Our best reaction yields (electrons/CO{sub 2}) were on the order of 10{sup -3}; well below the 75% values first reported by Somorjai (we note they have also been unable to reproduce their early results). Over the course of this Project we have determined that the whole concept of 'chemicurrent', in fact, may be an illusion. Our results conclusively demonstrate that the current measured from our nanodiodes is derived from a thermoelectric voltage; we have found no credible evidence for true chemicurrent. Unfortunately this means that the catalytic nanodiode has no future as a micropower source.

  10. Cold Spring Harbor symposia on quantitative biology: Volume 52, Evolution of catalytic function

    Energy Technology Data Exchange (ETDEWEB)

    1987-01-01

    This document contains 97 papers presented at the symposium. The primary topic was the evolution of the catalytic function. Speakers discussed the evolution of genetic apparatus, the primordial soup, the anatomy of RNA, RNA templates, protein assembly, protein structure, cofactors, ribosomes, exons, and introns. Individual papers were processed separately for the data base. (TEM)

  11. Electro-catalytic properties of bi-(Fe and Co shungite composites

    Directory of Open Access Journals (Sweden)

    Bazarbay Serikbayev

    2012-03-01

    Full Text Available The paper presents the results of electrochemical studies obtained on carbon paste electrodes (СPE from Koksu shungite (Ш. The electrochemical and electro-catalytic properties of electrode are compared based on a natural shungite and its modified form with iron and cobalt.

  12. Electro-catalytic properties of bi-(Fe and Co) shungite composites

    OpenAIRE

    Bazarbay Serikbayev; Duisek Kamisbaev; Z. Tilepbergen; O. Ahmet; Zhalgas Uteuliyev

    2012-01-01

    The paper presents the results of electrochemical studies obtained on carbon paste electrodes (СPE) from Koksu shungite (Ш). The electrochemical and electro-catalytic properties of electrode are compared based on a natural shungite and its modified form with iron and cobalt.

  13. Advances and perspectives in catalytic oxidation of hydrocarbons in liquid phase

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    This review article summarizes recent advances in catalytic oxidation of hydrocarbons, especially presents two strategies for activation of C-H bonds or molecular oxygen. Based on our own research results, the applications of the two methods in the oxidation of cyclohexane, toluene and ethyl benzene, etc. are introduced, and the perspectives of the two methods are also discussed.

  14. Study on catalytic oxidation for p-xylene to p-toluic acid by unsymmetrical Schiff base complexes with pendant aza-crown ether%氮杂冠醚取代非对称双Schiff碱配合物催化氧化对二甲苯研究

    Institute of Scientific and Technical Information of China (English)

    曾凤春; 何锡阳; 李建章; 杨柱柱; 程杰; 肖正华

    2012-01-01

    将一系列苯并-10-氮杂-15-冠-5或吗啉基取代的不对称双Schiff碱配合物作为催化剂,在常压和120℃条件下用于催化氧化对二甲苯研究.探讨了Schiff配合物中心金属离子、Schiff碱配体中挂接的氮杂冠醚环、配体芳环上取代基等对催化氧化对二甲苯反应活性及其氧化产物选择性的影响.实验结果表明:配合物中氮杂冠醚的存在能显著缩短反应诱导期、提高催化活性和选择性;Schiff碱Mn(Ⅲ)配合物比Schiff碱Co(Ⅱ)和Schiff碱Cu(Ⅱ)具有更高的催化活性;氮杂冠醚Schiff碱Mn(Ⅲ)配合物催化氧化二甲苯的转化率和产物选择性分别达75%和90%.%Unsymmetrical Schiff base complexes with pendant aza-crown or morpholino groups had been studied as catalysts in aerobic oxidation of p-xylene top-toluic acid(FTA)with air at 120℃ under normal atmospheric pressure. The effects of central metal of Schiff base complexes, the aza-crown ether group pendant and substituents group in Schiff base ligands on the oxidation of p-xylene were also investigated. The results revealed that the catalytic activity of Schiff base complexes binding benzo-10-aza-crown ether pendants could be visibly improved and the induce period of the oxidation for p-xylene to p-toluic acid was shortened. Schiff base manganese (Ⅲ) complexes had higher catalytic activity than both cobalt(Ⅱ)and copper( Ⅱ) complexes. Significant selectivity (up to 90% )and conversion levels (up to -75% )were obtained in the presence of aza-crown ether substituted unsymmetrical Schiff base Mn( Ⅲ) complexes.

  15. 氮杂冠醚取代单Schiff碱过渡金属配合物催化氧化对二甲苯研究%Study on catalytic oxidation for p-xylene to p-toluic acid by mono-Schiff base complexes with pendant aza-crown ether

    Institute of Scientific and Technical Information of China (English)

    王涛; 李建章; 魏磊; 胡伟; 程杰; 向珍

    2012-01-01

    本文将苯并-10-氮杂-15-冠-5或吗啉基取代的单Schiff碱过渡配合物作为催化剂,在常压和120℃条件下,以空气为氧源,研究了对二甲苯催化氧化反应.实验探讨了Schiff碱配合物中心金属离子、Schiff碱配体中挂接的氮杂冠醚环、配体芳环上取代基和反应时间等对对二甲苯催化氧化反应的影响.实验结果表明:Schiff碱配合物中氮杂冠醚的存在能显著缩短反应诱导期,提高催化反应活性和产物选择性;Schiff碱Mn(Ⅲ)配合物比Schiff碱Co(Ⅱ)具有更高的催化反应活性;氮杂冠醚Schiff碱Mn(Ⅲ)配合物对于二甲苯的催化氧化反应转化率大于60%,对甲苯甲酸产物的选择性均高于70%.%,mono-Schiff base complexes with pendant aza-crown or morpholino groups had been studied as catalysts in aerobic oxidation of P-xylene to p-toluic acid( PTA) with air at 120℃ under normal atmospheric pressure. The effects of central metal of Schiff base complexes, the aza-crown ether group pendant and the substituents group in Schiff base Uganda and the reaction time on the oxidation of p-xylene were also investigated. The results revealed that the catalytic activity of mono-Schiff base complexes binding aza-crown ether pendants could be visibly improved and the induce period of the oxidation for p-xylene to p-toluic acid was shortened. Schiff base manganese (Ⅲ) complexes had higher catalytic activity than cobalt ( Ⅱ ) complexes under the same lig-and. Significant selectivity ( up to -70% )and conversion levels (up to ~60% )were obtained in the presence of aza-crown ether substituted mono-Schiff base Mn (Ⅲ) complexes.

  16. Catalytic inhibition of topoisomerase II by a novel rationally designed ATP-competitive purine analogue

    Directory of Open Access Journals (Sweden)

    Schlaeppi Jean-Marc

    2009-01-01

    Full Text Available Abstract Background Topoisomerase II poisons are in clinical use as anti-cancer therapy for decades and work by stabilizing the enzyme-induced DNA breaks. In contrast, catalytic inhibitors block the enzyme before DNA scission. Although several catalytic inhibitors of topoisomerase II have been described, preclinical concepts for exploiting their anti-proliferative activity based on molecular characteristics of the tumor cell have only recently started to emerge. Topoisomerase II is an ATPase and uses the energy derived from ATP hydrolysis to orchestrate the movement of the DNA double strands along the enzyme. Thus, interfering with ATPase function with low molecular weight inhibitors that target the nucleotide binding pocket should profoundly affect cells that are committed to undergo mitosis. Results Here we describe the discovery and characterization of a novel purine diamine analogue as a potent ATP-competitive catalytic inhibitor of topoisomerase II. Quinoline aminopurine compound 1 (QAP 1 inhibited topoisomerase II ATPase activity and decatenation reaction at sub-micromolar concentrations, targeted both topoisomerase II alpha and beta in cell free assays and, using a quantitative cell-based assay and a chromosome segregation assay, displayed catalytic enzyme inhibition in cells. In agreement with recent hypothesis, we show that BRCA1 mutant breast cancer cells have increased sensitivity to QAP 1. Conclusion The results obtained with QAP 1 demonstrate that potent and selective catalytic inhibition of human topoisomerase II function with an ATP-competitive inhibitor is feasible. Our data suggest that further drug discovery efforts on ATP-competitive catalytic inhibitors are warranted and that such drugs could potentially be developed as anti-cancer therapy for tumors that bear the appropriate combination of molecular alterations.

  17. Removal of ammonia solutions used in catalytic wet oxidation processes.

    Science.gov (United States)

    Hung, Chang Mao; Lou, Jie Chung; Lin, Chia Hua

    2003-08-01

    Ammonia (NH(3)) is an important product used in the chemical industry, and is common place in industrial wastewater. Industrial wastewater containing ammonia is generally either toxic or has concentrations or temperatures such that direct biological treatment is unfeasible. This investigation used aqueous solutions containing more of ammonia for catalytic liquid-phase oxidation in a trickle-bed reactor (TBR) based on Cu/La/Ce composite catalysts, prepared by co-precipitation of Cu(NO(3))(2), La(NO(3))(2), and Ce(NO(3))(3) at 7:2:1 molar concentrations. The experimental results indicated that the ammonia conversion of the wet oxidation in the presence of the Cu/La/Ce composite catalysts was determined by the Cu/La/Ce catalyst. Minimal ammonia was removed from the solution by the wet oxidation in the absence of any catalyst, while approximately 91% ammonia removal was achieved by wet oxidation over the Cu/La/Ce catalyst at 230 degrees C with oxygen partial pressure of 2.0 MPa. Furthermore, the effluent streams were conducted at a liquid hourly space velocity of under 9 h(-1) in the wet catalytic processes, and a reaction pathway was found linking the oxidizing ammonia to nitric oxide, nitrogen and water. The solution contained by-products, including nitrates and nitrites. Nitrite selectivity was minimized and ammonia removal maximized when the feed ammonia solution had a pH of around 12.0.

  18. Catalytic graphitization of carbon/carbon composites by lanthanum oxide

    Institute of Scientific and Technical Information of China (English)

    ZHANG Can; LU Guimin; SUN Ze; YU Jianguo

    2012-01-01

    Graphitized carbon/carbon composites were prepared by the process of catalytic graphitization with the rare-earth catalyst,lanthanum oxide (La2O3),in order to increase the degree of graphitization and reduce the electrical resistivity.The modified coal tar pitch and coal-based needle coke were used as carbon source,and a small amount of La2O3 was added to catalyze the graphitization of the disordered carbon materials.The effects of La2O3 catalyst on the graphitization degree and microstructure oftbe carbon/carbon composites were investigated by X-ray diffraction,scanning electron microscopy,and Raman spectroscopy.The results showed that La2O3 promoted the formation of more perfect and larger crystallites,and improved the electrical/mechanical properties of carbon/carbon composites.Carbon/carbon composites with a lower electrical resistivity (7.0 μΩ·m) could be prepared when adding 5 wt.% La2O3 powder with heating treatment at 2800 ℃.The catalytic effect of La2O3 for the graphitization of carbon/carbon composites was analyzed.

  19. Catalytic destruction of dichloromethane using perovskite-type oxide catalysts.

    Science.gov (United States)

    Lou, Jie-Chung; Hung, Chang-Mao; Yang, Bor-Yu

    2004-06-01

    Dichloromethane (DCM, also known as methylene chloride [CH2Cl2]) is often present in industrial waste gas and is a valuable chemical product in the chemical industry. This study addresses the oxidation of airstreams that contain CH2Cl2 by catalytic oxidation in a tubular fixed-bed reactor over perovskite-type oxide catalysts. This work also considers how the concentration of influent CH2Cl2 (Co = 500-1000 ppm), the space velocity (GHSV = 5000-48,000 1/hr), the relative humidity (RH = 10-70%) and the concentration of oxygen (O2 = 5-21%) influence the operational stability and capacity for the removal of CH2Cl2. The surface area of lanthanum (La)-cobalt (Co) composite catalyst was the greatest of the five perovskite-type catalysts prepared in various composites of La, strontium, and Co metal oxides. Approximately 99.5% CH2Cl2 reduction was achieved by the catalytic oxidation over LaCoO3-based perovskite catalyst at 600 degrees C. Furthermore, the effect of the initial concentration and reaction temperature on the removal of CH2Cl2 in the gaseous phase was also monitored. This study also provides information that a higher humidity corresponds to a lower conversion. Carbon dioxide and hydrogen chloride were the two main products of the oxidation process at a relative humidity of 70%.

  20. Evolution of toxicity upon wet catalytic oxidation of phenol.

    Science.gov (United States)

    Santos, A; Yustos, P; Quintanilla, A; García-Ochoa, F; Casas, J A; Rodríguez, J J

    2004-01-01

    This work reports on the evolution of the toxicity of phenol-containing simulated wastewater upon catalytic wet oxidation with a commercial copper-based catalyst (Engelhard Cu-0203T). The results of the study show that this catalyst enhances detoxification, in addition to its effect on the oxidation rate. The EC50 values of the intermediates identified throughout the oxidation route of phenol have been determined and used to predict the evolution of toxicity upon oxidation. The predicted values have been compared with the ones measured directly from the aqueous solution during the oxidation process. To learn about the evolution of toxicity through out the routes of phenol oxidation, experiments have been performed with simulated wastewaters containing separately phenol, catechol, and hydroquinone as original pollutants. The significant increase of toxicity observed during the early stages of phenol oxidation is not directly related to the development of the brown color that derives mainly from catechol oxidation. This increase of toxicity is caused by the formation of hydroquinone and p-benzoquinone as intermediates, the former showing the highest toxicity. Furthermore, synergistic effects, giving rise to a significant increase of toxicity, have been observed. These effects derive from the interactions among copper leached from the catalyst and catechol, hydroquinone, and p-benzoquinone and demand that close attention be paid to this potential problem in catalytic wet oxidation.

  1. Catalytic Reduction of NO and NOx Content in Tobacco Smoke

    Directory of Open Access Journals (Sweden)

    Cvetkovic N

    2014-12-01

    Full Text Available In order to reduce the nitric oxide (NO and nitrogen oxides (NO content in mainstream tobacco smoke, a new class of catalyst based on Cu-ZSM-5 zeolite has been synthesized. The effectiveness of the new catalyst (degree of reduction and specific catalytic ability was tested both by adding Cu-ZSM-5 zeolite directly to the tobacco blend and by addition to the filter. We have determined that adding the catalyst to the tobacco blend does not cause any changes in the physical, chemical or organoleptic properties of the cigarette blend. But, the addition reduces the yield of nitrogen oxides while having no influence on nicotine and “tar” content in the tobacco smoke of the modified blend. The catalyst addition increases the static burning rate (SBR. The changes in the quantity of NO and NOmay be explained by changes in burning conditions due to the increase of Oobtained from catalytic degradation of NO and NO, and adsorptive and diffusive properties of the catalyst. The changes in mainstream smoke analytes are also given on a puff-by-puff basis.

  2. Copper on activated carbon for catalytic wet air oxidation

    Directory of Open Access Journals (Sweden)

    Nora Dolores Martínez

    2009-03-01

    Full Text Available Textile industry is an important source of water contamination. Some of the organic contaminants cannot be eliminated by nature in a reasonable period. Heterogeneous catalytic wet air oxidation is one of the most effective methods to purify wastewater with organic contaminants. In this work, catalysts based on copper supported on activated carbon were synthesized. The activated carbons were obtained from industrial wastes (apricot core and grape stalk of San Juan, Argentina. These were impregnated with a copper salt and thermically treated in an inert atmosphere. Analysis of specific surface, pore volume, p zc, acidity, basicity and XRD patterns were made in order to characterize the catalysts. The catalytic activity was tested in the oxidation of methylene blue (MB and polyvinyl alcohol (PVA in aqueous phase with pure oxygen. Reaction tests were carried out in a Parr batch reactor at different temperatures, with a 0.2 MPa partial pressure of oxygen. The amount of unconverted organics was measured by spectrophotometry. Higher temperatures were necessary for the degradation of PVA compared to those for methylene blue.

  3. Non-equilibrium model for catalytic distillation process

    Institute of Scientific and Technical Information of China (English)

    Feng WANG; Ning ZHAO; Junping LI; Fukui XIAO; Wei WEI; Yuhan SUN

    2008-01-01

    A new improved tri-diagonal method was developed for the non-equilibrium stage model of the catalytic distillation by coupling consumptive reaction coefficient. The reactions in the distillation column were divided into generative reaction and consumptive reac-tion. The non-equilibrium stage model was introduced for the catalytic distillation process of the dimethyl car-bonate (DMC) synthesis by urea methanolysis over solid based catalyst, and the improved tri-diagonal method was used to solve the model equations. Comparison of pre-dicted results with experiment data shows that the mean relative error of the yield of DMC was 3.78% under dif-ferent conditions such as different operating pressures and reaction temperatures. The improved tri-diagonal matrix method could avoid the negative values of the liquid com-positions during the calculations and restrain the fluc-tuation of compositions by slowing down the variations of the values in the iteration. The modeling results show that the improved tri-diagonal method was appropriate for system containing a wide range of boiling point com-ponents and a different rate of reactions.

  4. Catalytic CVD of SWCNTs at Low Temperatures and SWCNT Devices

    Science.gov (United States)

    Seidel, Robert; Liebau, Maik; Unger, Eugen; Graham, Andrew P.; Duesberg, Georg S.; Kreupl, Franz; Hoenlein, Wolfgang; Pompe, Wolfgang

    2004-09-01

    New results on the planar growth of single-walled carbon nanotubes (SWCNTs) by catalytic chemical vapor deposition (CVD) at low temperatures will be reported. Optimizing catalyst, catalyst support, and growth parameters yields SWCNTs at temperatures as low as 600 °C. Growth at such low temperatures largely affects the diameter distribution since coalescence of the catalyst is suppressed. A phenomenological growth model will be suggested for CVD growth at low temperatures. The model takes into account surface diffusion and is an alternative to the bulk diffusion based vapor-liquid-solid (VLS) model. Furthermore, carbon nanotubes field effect transistors based on substrate grown SWCNTs will be presented. In these devices good contact resistances could be achieved by electroless metal deposition or metal evaporation of the contacts.

  5. Advanced treatment of biologically pretreated coal gasification wastewater by a novel integration of heterogeneous catalytic ozonation and biological process.

    Science.gov (United States)

    Zhuang, Haifeng; Han, Hongjun; Jia, Shengyong; Hou, Baolin; Zhao, Qian

    2014-08-01

    Advanced treatment of biologically pretreated coal gasification wastewater (CGW) was investigated employing heterogeneous catalytic ozonation integrated with anoxic moving bed biofilm reactor (ANMBBR) and biological aerated filter (BAF) process. The results indicated that catalytic ozonation with the prepared catalyst (i.e. MnOx/SBAC, sewage sludge was converted into sludge based activated carbon (SBAC) which loaded manganese oxides) significantly enhanced performance of pollutants removal by generated hydroxyl radicals. The effluent of catalytic ozonation process was more biodegradable and less toxic than that in ozonation alone. Meanwhile, ANMBBR-BAF showed efficient capacity of pollutants removal in treatment of the effluent of catalytic ozonation at a shorter reaction time, allowing the discharge limits to be met. Therefore, the integrated process with efficient, economical and sustainable advantages was suitable for advanced treatment of real biologically pretreated CGW.

  6. Probing the Catalytic Mechanism of S-Ribosylhomocysteinase (LuxS) with Catalytic Intermediates and Substrate Analogues

    Energy Technology Data Exchange (ETDEWEB)

    Gopishetty, Bhaskar; Zhu, Jinge; Rajan, Rakhi; Sobczak, Adam J.; Wnuk, Stanislaw F.; Bell, Charles E.; Pei, Dehua; (OSU); (FIU)

    2009-05-12

    S-Ribosylhomocysteinase (LuxS) cleaves the thioether bond in S-ribosylhomocysteine (SRH) to produce homocysteine (Hcys) and 4,5-dihydroxy-2,3-pentanedione (DPD), the precursor of the type II bacterial quorum sensing molecule (AI-2). The catalytic mechanism of LuxS comprises three distinct reaction steps. The first step involves carbonyl migration from the C1 carbon of ribose to C2 and the formation of a 2-ketone intermediate. The second step shifts the C=O group from the C2 to C3 position to produce a 3-ketone intermediate. In the final step, the 3-ketone intermediate undergoes a {beta}-elimination reaction resulting in the cleavage of the thioether bond. In this work, the 3-ketone intermediate was chemically synthesized and shown to be chemically and kinetically competent in the LuxS catalytic pathway. Substrate analogues halogenated at the C3 position of ribose were synthesized and reacted as time-dependent inhibitors of LuxS. The time dependence was caused by enzyme-catalyzed elimination of halide ions. Examination of the kinetics of halide release and decay of the 3-ketone intermediate catalyzed by wild-type and mutant LuxS enzymes revealed that Cys-84 is the general base responsible for proton abstraction in the three reaction steps, whereas Glu-57 likely facilitates substrate binding and proton transfer during catalysis.

  7. Theoretical study of catalytic efficiency of a Diels-Alderase catalytic antibody: an indirect effect produced during the maturation process.

    Science.gov (United States)

    Martí, Sergio; Andrés, Juan; Moliner, Vicent; Silla, Estanislao; Tuñón, Iñaki; Bertrán, Juan

    2008-01-01

    The Diels-Alder reaction is one of the most important and versatile transformations available to organic chemists for the construction of complex natural products, therapeutics agents, and synthetic materials. Given the lack of efficient enzymes capable of catalyzing this kind of reaction, it is of interest to ask whether a biological catalyst could be designed from an antibody-combining site. In the present work, a theoretical study of the different behavior of a germline catalytic antibody (CA) and its matured form, 39 A-11, that catalyze a Diels-Alder reaction has been carried out. A free-energy perturbation technique based on a hybrid quantum-mechanics/molecular-mechanics scheme, together with internal energy minimizations, has allowed free-energy profiles to be obtained for both CAs. The profiles show a smaller barrier for the matured form, which is in agreement with the experimental observation. Free-energy profiles were obtained with this methodology, thereby avoiding the much more demanding two-dimensional calculations of the energy surfaces that are normally required to study this kind of reaction. Structural analysis and energy evaluations of substrate-protein interactions have been performed from averaged structures, which allows understanding of how the single mutations carried out during the maturation process can be responsible for the observed fourfold enhancement of the catalytic rate constant. The conclusion is that the mutation effect in this studied germline CA produces a complex indirect effect through coupled movements of the backbone of the protein and the substrate.

  8. Millisecond autothermal catalytic reforming of carbohydrates for synthetic fuels by reactive flash volatilization

    Science.gov (United States)

    Dauenhauer, Paul Jakob

    Carbohydrates including glucose, cellulose, starch and polyols including glycerol, ethylene glycol and methanol produced in large quantities from biomass are considered as a carbon-based feedstock for high temperature catalytic reforming by catalytic partial oxidation. Autothermal catalytic partial oxidation of methanol, ethylene glycol, and glycerol with Rh and Pt-based catalysts with ceria on alumina foam supports at residence times less than ten milliseconds produced equilibrium selectivity to synthesis gas. The addition of steam at S/C>4 produced selectivity to H2 higher than 80% with little or no selectivity to minor products. In a new process referred to as 'reactive flash volatilization,' catalytic partial oxidation was combined with pyrolysis of biomass by directly impinging particles of cellulose, starch, polyethylene, soy oil, or Aspen (Populous Tremuloides) on an operating Rh-based reforming catalyst at 700-800°C. Solid particles endothermically pyrolyzed to volatile organic compounds which mixed with air and reformed on the catalyst exothermically generating heat to drive the overall process. Particles of ˜250 mum microcrystalline cellulose processed at the conditions of C/O=1.0 on a RhCe/gamma-Al2O3/alpha-Al 2O3 at a residence time of ˜70 milliseconds produced a gaseous effluent stream selecting for 50% H2 and 50% CO with no observable side products other than H2O and CO2, and residence time.

  9. Heterogeneous catalytic materials solid state chemistry, surface chemistry and catalytic behaviour

    CERN Document Server

    Busca, Guido

    2014-01-01

    Heterogeneous Catalytic Materials discusses experimental methods and the latest developments in three areas of research: heterogeneous catalysis; surface chemistry; and the chemistry of catalysts. Catalytic materials are those solids that allow the chemical reaction to occur efficiently and cost-effectively. This book provides you with all necessary information to synthesize, characterize, and relate the properties of a catalyst to its behavior, enabling you to select the appropriate catalyst for the process and reactor system. Oxides (used both as catalysts and as supports for cata

  10. Identification of catalytic residues using a novel feature that integrates the microenvironment and geometrical location properties of residues.

    Directory of Open Access Journals (Sweden)

    Lei Han

    Full Text Available Enzymes play a fundamental role in almost all biological processes and identification of catalytic residues is a crucial step for deciphering the biological functions and understanding the underlying catalytic mechanisms. In this work, we developed a novel structural feature called MEDscore to identify catalytic residues, which integrated the microenvironment (ME and geometrical properties of amino acid residues. Firstly, we converted a residue's ME into a series of spatially neighboring residue pairs, whose likelihood of being located in a catalytic ME was deduced from a benchmark enzyme dataset. We then calculated an ME-based score, termed as MEscore, by summing up the likelihood of all residue pairs. Secondly, we defined a parameter called Dscore to measure the relative distance of a residue to the center of the protein, provided that catalytic residues are typically located in the center of the protein structure. Finally, we defined the MEDscore feature based on an effective nonlinear integration of MEscore and Dscore. When evaluated on a well-prepared benchmark dataset using five-fold cross-validation tests, MEDscore achieved a robust performance in identifying catalytic residues with an AUC1.0 of 0.889. At a ≤ 10% false positive rate control, MEDscore correctly identified approximately 70% of the catalytic residues. Remarkably, MEDscore achieved a competitive performance compared with the residue conservation score (e.g. CONscore, the most informative singular feature predominantly employed to identify catalytic residues. To the best of our knowledge, MEDscore is the first singular structural feature exhibiting such an advantage. More importantly, we found that MEDscore is complementary with CONscore and a significantly improved performance can be achieved by combining CONscore with MEDscore in a linear manner. As an implementation of this work, MEDscore has been made freely accessible at http://protein.cau.edu.cn/mepi/.

  11. Partial catalytic oxidation of CH{sub 4} to synthesis gas for power generation - Final report

    Energy Technology Data Exchange (ETDEWEB)

    Mantzaras, I.; Schneider, A.

    2006-03-15

    The partial oxidation of methane to synthesis gas over rhodium catalysts has been investigated experimentally and numerically in the pressure range of 4 to 10 bar. The methane/oxidizer feed has been diluted with large amounts of H{sub 2}O and CO{sub 2} (up to 70% vol.) in order to simulate new power generation cycles with large exhaust gas recycle. Experiments were carried out in an optically accessible channel-flow reactor that facilitated laser-based in situ measurements, and also in a subscale gas-turbine catalytic reactor. Full-elliptic steady and transient two-dimensional numerical codes were used, which included elementary hetero-/homogeneous chemical reaction schemes. The following are the key conclusions: a) Heterogeneous (catalytic) and homogeneous (gas-phase) schemes have been validated for the partial catalytic oxidation of methane with large exhaust gas recycle. b) The impact of added H{sub 2}O and CO{sub 2} has been elucidated. The added H{sub 2}O increased the methane conversion and hydrogen selectivity, while it decreased the CO selectivity. The chemical impact of CO{sub 2} (dry reforming) was minimal. c) The numerical model reproduced the measured catalytic ignition times. It was further shown that the chemical impact of H{sub 2}O and CO{sub 2} on the catalytic ignition delay times was minimal. d) The noble metal dispersion increased with different support materials, in the order Rh/{alpha}-Al{sub 2}O{sub 3}, Rh/ZrO{sub 2}, and Rh/Ce-ZrO{sub 2}. An evident relationship was established between the noble metal dispersion and the catalytic behavior. (authors)

  12. Autoantibodies against the catalytic domain of BRAF are not specific serum markers for rheumatoid arthritis.

    Directory of Open Access Journals (Sweden)

    Wenli Li

    Full Text Available BACKGROUND: Autoantibodies to the catalytic domain of v-raf murine sarcoma viral oncogene homologue B1 (BRAF have been recently identified as a new family of autoantibodies involved in rheumatoid arthritis (RA. The objective of this study was to determine antibody responses to the catalytic domain of BRAF in RA and other autoimmune diseases. The association between RA-related clinical indices and these antibodies was also assessed. METHODOLOGY/PRINCIPAL FINDINGS: The presence of autoantibodies to the catalytic domain of BRAF (anti-BRAF or to peptide P25 (amino acids 656-675 of the catalytic domain of BRAF; anti-P25 was determined in serum samples from patients with RA, primary Sjögren's syndrome (pSS, systemic lupus erythematosus (SLE, and healthy controls by using indirect enzyme-linked immunosorbent assays (ELISAs based on the recombinant catalytic domain of BRAF or a synthesized peptide, respectively. Associations of anti-BRAF or anti-P25 with disease variables of RA patients were also evaluated. Our results show that the BRAF-specific antibodies anti-BRAF and anti-P25 are equally present in RA, pSS, and SLE patients. However, the erythrocyte sedimentation rate (ESR used to detect inflammation was significantly different between patients with and without BRAF-specific antibodies. The anti-BRAF-positive patients were found to have prolonged disease, and active disease occurred more frequently in anti-P25-positive patients than in anti-P25-negative patients. A weak but significant correlation between anti-P25 levels and ESRs was observed (r = 0.319, p = 0.004. CONCLUSIONS/SIGNIFICANCE: The antibody response against the catalytic domain of BRAF is not specific for RA, but the higher titers of BRAF-specific antibodies may be associated with increased inflammation in RA.

  13. Catalytic bioscavengers in nerve agent poisoning: A promising approach?

    Science.gov (United States)

    Worek, Franz; Thiermann, Horst; Wille, Timo

    2016-02-26

    The repeated use of the nerve agent sarin against civilians in Syria in 2013 emphasizes the continuing threat by chemical warfare agents. Multiple studies demonstrated a limited efficacy of standard atropine-oxime treatment in nerve agent poisoning and called for the development of alternative and more effective treatment strategies. A novel approach is the use of stoichiometric or catalytic bioscavengers for detoxification of nerve agents in the systemic circulation prior to distribution into target tissues. Recent progress in the design of enzyme mutants with reversed stereo selectivity resulting in improved catalytic activity and their use in in vivo studies supports the concept of catalytic bioscavengers. Yet, further research is necessary to improve the catalytic activity, substrate spectrum and in vivo biological stability of enzyme mutants. The pros and cons of catalytic bioscavengers will be discussed in detail and future requirements for the development of catalytic bioscavengers will be proposed.

  14. Catalytic Synthesis Methods for Triazolopyrimidine Derivatives

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    A new method for catalyzed synthesis of triazolopyrimidine derivatives is reported. Aikylamine reaction with dialkyl cyanodithioiminocarbonate was catalyzed by quaternary ammonium salts at room temperature to yield 3-alkylamine-5-amino-1,2,4-triazole in good quality and high yields. After imidization and reaction with an α,β-unsaturated acid derivative, the reaction intermediate was hydrolyzed in the presence of a Lewis acid to obtain the target product. This novel catalytic method for triazolopyrimidine derivatives can be carried out under inexpen-sive and mild conditions, and is safe and environmentally friendly. IH NMR results for all intermediates are re-ported.

  15. Thin film porous membranes for catalytic sensors

    Energy Technology Data Exchange (ETDEWEB)

    Hughes, R.C.; Boyle, T.J.; Gardner, T.J. [and others

    1997-06-01

    This paper reports on new and surprising experimental data for catalytic film gas sensing resistors coated with nanoporous sol-gel films to impart selectivity and durability to the sensor structure. This work is the result of attempts to build selectivity and reactivity to the surface of a sensor by modifying it with a series of sol-gel layers. The initial sol-gel SiO{sub 2} layer applied to the sensor surprisingly showed enhanced O{sub 2} interaction with H{sub 2} and reduced susceptibility to poisons such as H{sub 2}S.

  16. Catalytic Synthesis of Nitriles in Continuous Flow

    DEFF Research Database (Denmark)

    Nordvang, Emily Catherine

    , alternative path to acetonitrile from ethanol via the oxidative dehydrogenation of ethylamine. The catalytic activity and product ratios of the batch and continuous flow reactions are compared and the effect of reaction conditions on the reaction is investigated. The effects of ammonia in the reaction...... dehydrogenation of ethylamine and post-reaction purging.Chapter 4 outlines the application of RuO2/Al2O3 catalysts to the oxidative dehydrogenation of benzylamine in air, utilizing a new reaction setup. Again, batch and continuous flow reactions are compared and the effects of reaction conditions, ammonia...

  17. Biomimetic, Catalytic Oxidation in Organic Synthesis

    Institute of Scientific and Technical Information of China (English)

    Shun-lchi Murahashi

    2005-01-01

    @@ 1Introduction Oxidation is one of the most fundamental reactions in organic synthesis. Owing to the current need to develop forward-looking technology that is environmentally acceptable with respect many aspects. The most attractive approaches are biomimetic oxidation reactions that are closely related to the metabolism of living things. The metabolisms are governed by a variety of enzymes such as cytochrome P-450 and flavoenzyme.Simulation of the function of these enzymes with simple transition metal complex catalyst or organic catalysts led to the discovery of biomimetic, catalytic oxidations with peroxides[1]. We extended such biomimetic methods to the oxidation with molecular oxygen under mild conditions.

  18. Catalytic wet oxidation of black liquor

    OpenAIRE

    Viader Riera, Gerard

    2012-01-01

    The major aspects of wet air oxidation and catalytic wet air oxidation have been reviewed in this work paying special attention to the reaction mechanisms, kinetics and the industrial process. In the experimental section a set of heterogeneous catalysts have been tested in the wet oxidation of non-wood black liquor. The oxidation runs were performed batchwise in a laboratory-scale mechanically stirred slurry reactor for 1 h at a temperature of 170°C and total pressure of 12 bar. Pure oxygen w...

  19. Catalytic enantioselective synthesis of quaternary carbon stereocentres

    Science.gov (United States)

    Quasdorf, Kyle W.; Overman, Larry E.

    2014-12-01

    Quaternary carbon stereocentres--carbon atoms to which four distinct carbon substituents are attached--are common features of molecules found in nature. However, before recent advances in chemical catalysis, there were few methods of constructing single stereoisomers of this important structural motif. Here we discuss the many catalytic enantioselective reactions developed during the past decade for the synthesis of single stereoisomers of such organic molecules. This progress now makes it possible to incorporate quaternary stereocentres selectively in many organic molecules that are useful in medicine, agriculture and potentially other areas such as flavouring, fragrances and materials.

  20. 多酸基金属-有机框架的构筑及其催化性能%Structures and catalytic performances of two polyoxometalate-based metal-organic frameworks

    Institute of Scientific and Technical Information of China (English)

    黄远; 王书改; 李雯雯; 韩秋霞

    2016-01-01

    Two phosphotungstate incorporated metal‐organic frameworks (1)[Er2 H(μ‐O)2 (dp‐do)4 (H2O)2 ][PW12 O40 ] ・ 3H2O and (2) [Tm2 H(μ‐O)2 (dpdo)4 (H2O )2 ][PW12 O40 ] ・ 3H2O (dpdo = 4 ,4′‐Bipyridine‐N ,N′‐dioxide) have been synthesized through a one‐step hydrothermal reaction and characterized by elemental analyses ,IR spectra ,and single‐crystal X‐ray diffrac‐tion .Kinetic experiments for the hydrolytic cleavage of DNA‐model phosphodiester BNPP (bis (p‐nitropheny)phosphate) were followed spectrophotometrically for the absorbance increase at 400 nm in EPPS (4‐(2‐hydroxyethyl)piperazine‐1‐propane sulfonic acid) buffer solution due to the formation of p‐nitrophenoxide with 1 and 2 under conditions of pH = 4 .0 and 50 oC .UV spectroscopy indicates that the cleavage of the phosphodiester bond proceeds with the pseudo‐first‐order rate constant in the range of 10 - 7 - 10 - 6 s - 1 ,giving an inorganic phosphate and p‐nitrophenol as the final products of hydrolysis .The results demonstrate that 1 and 2 have good catalytic activity and reusability for hydrolytic cleavage of BNPP .%在水热条件下合成了两个基于 Keggin 型磷钨酸盐的金属‐有机框架化合物(MOFs)[Er2 H(μ‐O )2(dp‐do)4(H2 O)2][PW12 O40]・3H2 O (1)和[Tm2 H(μ‐O )2(dpdo)4(H2 O )2][PW12 O40]・3H2 O (2)(dpdo =4,4′‐bis(pyridine‐N‐oxide),并通过元素分析、红外光谱(IR)、紫外光谱(UV)及单晶 X 射线衍射(XRD)的方法对其进行了结构表征。此外,通过紫外‐可见分光光度法,在 EPPS 缓冲溶液中,考察了两种化合物在非均相体系中催化DNA 模型磷酸二酯双(对硝基苯酚)磷酸二酯(BNPP)的水解进程。催化结果表明,在50℃,pH =4的条件下,两种催化剂对 BNNP 催化的一级水解裂解速率为10-7~10-6 s -1,最终产物为无机磷酸盐和对硝基苯酚。此外,该催