WorldWideScience

Sample records for catalytic oxidation reactions

  1. Process of forming catalytic surfaces for wet oxidation reactions

    Science.gov (United States)

    Jagow, R. B. (Inventor)

    1977-01-01

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

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2011-07-01

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

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

    DEFF Research Database (Denmark)

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

    2015-01-01

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

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

    Energy Technology Data Exchange (ETDEWEB)

    Ekerdt, J.G.

    1995-01-31

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

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

    Energy Technology Data Exchange (ETDEWEB)

    Ekerdt, J.G.

    1995-10-20

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

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

    Energy Technology Data Exchange (ETDEWEB)

    Ekerdt, John G.

    1999-07-31

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

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2015-01-01

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

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

    International Nuclear Information System (INIS)

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

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

    Institute of Scientific and Technical Information of China (English)

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

    2006-01-01

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

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

    Institute of Scientific and Technical Information of China (English)

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

    2003-01-01

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

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

    Science.gov (United States)

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

    2015-12-30

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

  12. Catalytic ammonia oxidation to nitrogen (I) oxide

    OpenAIRE

    MASALITINA NATALIYA YUREVNA; SAVENKOV ANATOLIY SERGEEVICH

    2015-01-01

    The process of synthesis of nitrous oxide by low-temperature catalytical oxidation of NH has been investigated for organic synthesis. The investigation has been carried out by the stage separation approach with NH oxidation occurring in several reaction zones, which characterized by different catalytic conditions. The selectivity for N₂O was 92–92,5 % at the ammonia conversion of 98–99.5 % in the optimal temperature range.

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2014-05-01

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

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

    International Nuclear Information System (INIS)

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

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

    OpenAIRE

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

    2015-01-01

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

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

    KAUST Repository

    Chaparala, Sree Vidya

    2015-06-11

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

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

    Science.gov (United States)

    Cuba Torres, Christian Martin

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

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

    Energy Technology Data Exchange (ETDEWEB)

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

    1985-05-01

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

  19. Fluctuations in catalytic surface reactions

    CERN Document Server

    Imbihl, R

    2003-01-01

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

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

    International Nuclear Information System (INIS)

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

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

    International Nuclear Information System (INIS)

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

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

    International Nuclear Information System (INIS)

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

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

    Science.gov (United States)

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

    1994-10-01

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

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

    International Nuclear Information System (INIS)

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

  5. 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.

  6. 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.

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

    Indian Academy of Sciences (India)

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

    2013-01-01

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

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

    International Nuclear Information System (INIS)

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

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

    International Nuclear Information System (INIS)

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

  10. 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.

  11. 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.

  12. Catalytic, enantioselective, vinylogous aldol reactions.

    Science.gov (United States)

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

    2005-07-25

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

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

    International Nuclear Information System (INIS)

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

  14. 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

  15. 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.

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

    Institute of Scientific and Technical Information of China (English)

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

    2012-01-01

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

  17. Catalytic methanation reaction over alumina supported cobalt oxide doped noble metal oxides for the purification of simulated natural gas

    Institute of Scientific and Technical Information of China (English)

    Wan Azelee Wan Abu Bakar; Rusmidah Ali; Abdul Aziz Abdul Kadir; Salmiah Jamal Mat Rosid; Nurul Shafeeqa Mohammad

    2012-01-01

    A series of alumina supported cobalt oxide based catalysts doped with noble metals such as ruthenium and platinum were prepared by wet impregnation method.The variables studied were difference ratio and calcination temperatures.Pt/Co( 10∶90 )/Al2O3 catalyst calcined at 700 ℃ was found to be the best catalyst which able to convert 70.10% of CO2 into methane with 47% of CH4 formation at maximum temperature studied of 400 ℃.X-ray diffraction analysis showed that this catalyst possessed the active site Co3O4 in face-centered cubic and PtO2 in the orthorhombic phase with Al2O3 existed in the cubic phase.According to the FESEM micrographs,both fresh and spent Pt/Co( 10∶90)/Al2O3 catalysts displayed small particle size with undefined shape.Nitrogen Adsorption analysis showed that 5.50% reduction of the total surface area for the spent Pt/Co( 10∶90)/Al2O3 catalyst.Meanwhile,Energy Dispersive X-ray analysis (EDX) indicated that Co and Pt were reduced by 0.74% and 0.14% respectively on the spent Pt/Co( 10∶90)/Al2O3catalyst.Characterization using FT-IR and TGA-DTA analysis revealed the existence of residual nitrate and hydroxyl compounds on the Pt/Co( 10∶90)/Al2O3 catalyst.

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

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

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

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2013-12-28

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

  20. Preparation and Catalytic Oxidation Activity on 2-mercaptoethanol of a Novel Catalytic Cellulose Fibres

    Institute of Scientific and Technical Information of China (English)

    YAO Yu-yuan; LI Ying-jie; CHEN Wen-xing; Lü Wang-yang; Lü Su-fang; XU Min-hong; LIU Fan

    2007-01-01

    Cobalt tetra(N-carbonylacylic) aminophthalocyanine was supported on cellulose fibres by graft reaction to obtain a novel polymer catalyst, catalytic cellulose fibres (CCF),and the optimal supporting conditions were pH = 6, 80℃,t = 120 min. The catalytic oxidation activity of CCF towards oxidation of 2-mereaptoethanol (MEA) in aqueous solution was investigated. The experimental results demonstrated that CCF had good catalytic oxidation activity on MEA at room temperature, causing no secondary pollution and remaining efficient for the repetitive tests with no obvious decrease of catalytic activity.

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

    Science.gov (United States)

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

    2014-05-20

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

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

    Science.gov (United States)

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

    2015-05-26

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

  3. Exact Results for Kinetics of Catalytic Reactions

    OpenAIRE

    Frachebourg, L.; Krapivsky, P. L.

    1995-01-01

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

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2000-10-01

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

  5. 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.)

  6. One-pot synthesis of reduced graphene oxide supported PtCuy catalysts with enhanced electro-catalytic activity for the methanol oxidation reaction

    International Nuclear Information System (INIS)

    The outstanding performance PtCuy (y = 1,2,3) alloy nanoparticles supported on reduced graphene oxide (rGO) have been synthesized by a facile, efficient, one-pot hydrothermal synthesis approach. The as-prepared PtCuy/rGO catalysts are comprehensively characterized by X-ray diffraction, X-ray photoelectron spectroscopy, transmission electron microscopy. Cyclic voltammetry, CO-stripping voltammetry and chronoamperometry results reveal that the PtCuy/rGO catalysts have higher electro-catalytic activity, more negative onset oxidative potential, more excellent tolerance ability for CO poisoning and enhanced stability for the electro-oxidation of methanol compared to pure Pt/rGO. As far as the as-made PtCuy/rGO catalysts are concerned, the PtCu2/rGO exhibits the highest electro-catalytic activity. The mechanism of the promoting effect of Cu on Pt is explained based on the electronic modification effect. The nature of interfacial interactions between the Pt-Cu active metal phase and the rGO supporting materials is crucial to achieving high performance

  7. Catalytic reaction in confined flow channel

    Energy Technology Data Exchange (ETDEWEB)

    Van Hassel, Bart A.

    2016-03-29

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

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

    KAUST Repository

    Zhang, Tao

    2014-01-01

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

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

    Energy Technology Data Exchange (ETDEWEB)

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

    1995-03-01

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

  10. Catalytic reaction dynamics in inhomogeneous networks.

    Science.gov (United States)

    Watanabe, Akitomo; Yakubo, Kousuke

    2014-05-01

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

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

    International Nuclear Information System (INIS)

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

  12. Magnetic gold nanocatalyst (nanocat-Fe–Au): catalytic applications for the oxidative esterification and hydrogen transfer reactions

    Science.gov (United States)

    An efficient and sustainable protocol is described for the oxidative esterification of aldehydes and the reduction of aromatic nitro compounds that uses magnetically separable and reusable maghemite-supported gold nanocatalyst (nanocat-Fe-Au) under mild conditions. The complex ch...

  13. 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...

  14. From Catalytic Reaction Networks to Protocells

    Science.gov (United States)

    Kaneko, Kunihiko

    2013-12-01

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

  15. Heterogeneously Catalyzed Oxidation Reactions Using Molecular Oxygen

    DEFF Research Database (Denmark)

    Beier, Matthias Josef

    Heterogeneously catalyzed selective oxidation reactions have attracted a lot of attention in recent time. The first part of the present thesis provides an overview over heterogeneous copper and silver catalysts for selective oxidations in the liquid phase and compared the performance and catalytic...... that both copper and silver can function as complementary catalyst materials to gold showing different catalytic properties and being more suitable for hydrocarbon oxidation reactions. Potential opportunities for future research were outlined. In an experimental study, the potential of silver as a...... properties to the widely discussed gold catalysts. Literature results were summarized for alcohol oxidation, epoxidation, amine oxidation, phenol hydroxylation, silane and sulfide oxidation, (side-chain) oxidation of alkyl aromatic compounds, hydroquinone oxidation and cyclohexane oxidation. It was found...

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

    Energy Technology Data Exchange (ETDEWEB)

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

    1994-03-01

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

  17. Catalytic Conia-ene and related reactions.

    Science.gov (United States)

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

    2015-10-01

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

  18. Ubiquitous "glassy" relaxation in catalytic reaction networks

    OpenAIRE

    Awazu, Akinori; Kaneko, Kunihiko

    2009-01-01

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

  19. Chemical selforganization of composite catalysts during catalytic reactions

    Energy Technology Data Exchange (ETDEWEB)

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

    2012-10-15

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

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

    Energy Technology Data Exchange (ETDEWEB)

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

    1992-09-01

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

  1. Influence of Reaction Conditions on the Catalytic Oxidation of Cyclohexene with Molecular Oxygen Using a Series of Keggin-Type Polyoxometalate

    Directory of Open Access Journals (Sweden)

    Ramyah Radman

    2015-12-01

    Full Text Available A series of keggin-type polyoxometalatesnamely; H3PMo12O40,H3PW12O40, Fe1.5PW12O40 and Co1.5PW12O40 were prepared, characterized and tested for the oxidation of cyclohexene by molecular oxygen in acetonitrile medium. The oxidation gives 2-cyclohexen-1-ol, 2-cyclohexen-1-one and cyclohexene oxide,however, 2-cyclohexen-1-one was the major product.TheCo1.5PW12O40catalyst showed the highest catalytic activity for the oxidation reactionand it was chose to study the effect ofvaryingO2 pressure, time, temperature and catalyst weight. The highest percentage of cyclohexen econ version and selectivity of the major product 2-cyclohexen-1-one was obtained at 5bar of O2 pressure, 4h, 70 oC, and 900mg of Co1.5PW12O40 catalyst.

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

    Science.gov (United States)

    Awazu, Akinori; Kaneko, Kunihiko

    2009-10-01

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

  3. Catalytic oxidation of CS2 over atmospheric particles and oxide catalysts

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    The catalytic oxidization of CS2 over atmospheric particles and some oxide catalysts was explored through FT-IR, MS and a fixed-bed stainless steel reactor. The results show that at mospheric particles and some oxide catalysts exhibited considerable oxidizing activities for CS2 at ambient temperature. The reaction products are mainly COS and elemental sulfur, even CO2 on some catalysts. Among the catalysts, CaO has the strongest catalytic activity for oxidizing CS2. Fe2O3 is weaker than CaO. The catalytic activity for AI2O3 reduces considerably compared with the former two catalysts, and SiO2 the weakest. Atmospheric particle samples' catalytic activity is be tween Fe2O3's and AI2O3's. The atmospheric particle sample collected mainly consists of Ca(AI2Si2O8)· 4H2O, which is also the main component of cement. COS, the main product, is formed by the catalytic oxidization of CS2 with adsorbed “molecular” oxygen over the catalysts' surfaces. The concentration of adsorbed oxygen over catalysts' surfaces may be the key factor contributed to the oxidizing activity. It is indicated that CS2 could be catalytically oxidized over at mospheric particles, which induced that this reaction may be another important source of atmos pheric COS from CS2.

  4. Metallic Sn spheres and SnO2@C core-shells by anaerobic and aerobic catalytic ethanol and CO oxidation reactions over SnO2 nanoparticles

    Science.gov (United States)

    Kim, Won Joo; Lee, Sung Woo; Sohn, Youngku

    2015-08-01

    SnO2 has been studied intensely for applications to sensors, Li-ion batteries and solar cells. Despite this, comparatively little attention has been paid to the changes in morphology and crystal phase that occur on the metal oxide surface during chemical reactions. This paper reports anaerobic and aerobic ethanol and CO oxidation reactions over SnO2 nanoparticles (NPs), as well as the subsequent changes in the nature of the NPs. Uniform SnO2@C core-shells (10 nm) were formed by an aerobic ethanol oxidation reaction over SnO2 NPs. On the other hand, metallic Sn spheres were produced by an anaerobic ethanol oxidation reaction at 450 °C, which is significantly lower than that (1200 °C) used in industrial Sn production. Anaerobic and aerobic CO oxidation reactions were also examined. The novelty of the methods for the production of metallic Sn and SnO2@C core-shells including other anaerobic and aerobic reactions will contribute significantly to Sn and SnO2-based applications.

  5. 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.  ……

  6. Asymmetric Catalytic Reactions Catalyzed by Chiral Titanium Complexes

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

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

  7. 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

  8. Aerobic Alcohol Oxidation Using a Copper(I)/TEMPO Catalyst System: A Green, Catalytic Oxidation Reaction for the Undergraduate Organic Chemistry Laboratory

    Science.gov (United States)

    Hill, Nicholas J.; Hoover, Jessica M.; Stahl, Shannon S.

    2013-01-01

    Modern undergraduate organic chemistry textbooks provide detailed discussion of stoichiometric Cr- and Mn-based reagents for the oxidation of alcohols, yet the use of such oxidants in instructional and research laboratories, as well as industrial chemistry, is increasingly avoided. This work describes a laboratory exercise that uses ambient air as…

  9. Including lateral interactions into microkinetic models of catalytic reactions

    DEFF Research Database (Denmark)

    Hellman, Anders; Honkala, Johanna Karoliina

    2007-01-01

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

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

    OpenAIRE

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

    1992-01-01

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

  11. Metallic Sn spheres and SnO2@C core-shells by anaerobic and aerobic catalytic ethanol and CO oxidation reactions over SnO2 nanoparticles

    OpenAIRE

    Won Joo Kim; Sung Woo Lee; Youngku Sohn

    2015-01-01

    SnO2 has been studied intensely for applications to sensors, Li-ion batteries and solar cells. Despite this, comparatively little attention has been paid to the changes in morphology and crystal phase that occur on the metal oxide surface during chemical reactions. This paper reports anaerobic and aerobic ethanol and CO oxidation reactions over SnO2 nanoparticles (NPs), as well as the subsequent changes in the nature of the NPs. Uniform SnO2@C core-shells (10 nm) were formed by an aerobic eth...

  12. Recent Advances on Electro-Oxidation of Ethanol on Pt- and Pd-Based Catalysts: From Reaction Mechanisms to Catalytic Materials

    OpenAIRE

    Ye Wang; Shouzhong Zou; Wen-Bin Cai

    2015-01-01

    The ethanol oxidation reaction (EOR) has drawn increasing interest in electrocatalysis and fuel cells by considering that ethanol as a biomass fuel has advantages of low toxicity, renewability, and a high theoretical energy density compared to methanol. Since EOR is a complex multiple-electron process involving various intermediates and products, the mechanistic investigation as well as the rational design of electrocatalysts are challenging yet essential for the desired complete oxidation to...

  13. Discreteness-Induced Criticality in Random Catalytic Reaction Networks

    OpenAIRE

    Awazu, Akinori; Kaneko, Kunihiko

    2009-01-01

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

  14. Catalytic oxidation of dimethyl ether

    Energy Technology Data Exchange (ETDEWEB)

    Zelenay, Piotr; Wu, Gang; Johnston, Christina M.; Li, Qing

    2016-05-10

    A composition for oxidizing dimethyl ether includes an alloy supported on carbon, the alloy being of platinum, ruthenium, and palladium. A process for oxidizing dimethyl ether involves exposing dimethyl ether to a carbon-supported alloy of platinum, ruthenium, and palladium under conditions sufficient to electrochemically oxidize the dimethyl ether.

  15. Catalytic conversion of methane: Carbon dioxide reforming and oxidative coupling

    KAUST Repository

    Takanabe, Kazuhiro

    2012-01-01

    Natural gas conversion remains one of the essential technologies for current energy needs. This review focuses on the mechanistic aspects of the development of efficient and durable catalysts for two reactions, carbon dioxide reforming and the oxidative coupling of methane. These two reactions have tremendous technological significance for practical application in industry. An understanding of the fundamental aspects and reaction mechanisms of the catalytic reactions reviewed in this study would support the design of industrial catalysts. CO 2 reforming of methane utilizes CO 2, which is often stored in large quantities, to convert as a reactant. Strategies to eliminate carbon deposition, which is the major problem associated with this reaction, are discussed. The oxidative coupling of methane directly produces ethylene in one reactor through a slightly exothermic reaction, potentially minimizing the capital cost of the natural gas conversion process. The focus of discussion in this review will be on the attainable yield of C 2 products by rigorous kinetic analyses.

  16. Catalytic combustion over high temperature stable metal oxides

    Energy Technology Data Exchange (ETDEWEB)

    Berg, M. [TPS Termiska Processer AB, Nykoeping (Sweden)

    1996-12-31

    This thesis presents a study of the catalytic effects of two interesting high temperature stable metal oxides - magnesium oxide and manganese substituted barium hexa-aluminate (BMA) - both of which can be used in the development of new monolithic catalysts for such applications. In the first part of the thesis, the development of catalytic combustion for gas turbine applications is reviewed, with special attention to alternative fuels such as low-BTU gas, e.g. produced in an air blown gasifier. When catalytic combustion is applied for such a fuel, the primary advantage is the possibility of decreasing the conversion of fuel nitrogen to NO{sub x}, and achieving flame stability. In the experimental work, MgO was shown to have a significant activity for the catalytic combustion of methane, lowering the temperature needed to achieve 10 percent conversion by 270 deg C compared with homogeneous combustion.The reaction kinetics for methane combustion over MgO was also studied. It was shown that the heterogeneous catalytic reactions were dominant but that the catalytically initiated homogeneous gas phase reactions were also important, specially at high temperatures. MgO and BMA were compared. The latter showed a higher catalytic activity, even when the differences in activity decreased with increasing calcination temperature. For BMA, CO{sub 2} was the only product detected, but for MgO significant amounts of CO and C{sub 2}-hydrocarbons were formed. BMA needed a much lower temperature to achieve total conversion of other fuels, e.g. CO and hydrogen, compared to the temperature for total conversion of methane. This shows that BMA-like catalysts are interesting for combustion of fuel mixtures with high CO and H{sub 2} content, e.g. gas produced from gasification of biomass. 74 refs

  17. Catalytic Oxidation of Methane into Methanol over Copper-Exchanged Zeolites with Oxygen at Low Temperature

    OpenAIRE

    Narsimhan, Karthik; Iyoki, Kenta; Dinh, Kimberly; Román-Leshkov, Yuriy

    2016-01-01

    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 acti...

  18. Catalytic oxidation of industrial organic solvent vapors.

    Science.gov (United States)

    Tzortzatou, Katerina; Grigoropoulou, Eleni

    2010-01-01

    In the present study the catalytic oxidation of an industrial organic solvent consisting predominantly of C-9 to C-10 paraffins and napthtenics and derived from low aromatic white spirit on CuO and Pt catalysts was investigated at ambient pressure and temperatures between 330 and 770 K. Catalysts were prepared in the laboratory and compared to commercial ones. Characterization was based on x-ray diffraction (XRD) analysis, x-ray fluorescence (XRF) analysis, scanning electron microscope (SEM) analysis and nitrogen adsorption data. The commercial platinum catalyst was proved highly efficient in the oxidation of the commercial solvent, necessitating lower temperatures for total oxidation. Catalyst loading in active component is clearly not of primordial importance, since its dispersion and crystallinity as well as the presence of other metallic compounds influence also the catalytic activity. In the case of copper catalysts studied, the different support (alumina) characteristics also would contribute to the difference in catalytic activity. Finally, the power law kinetics may successfully be used in order to explain the catalytic oxidation data of the organic solvent, where its constituents are modeled as a single carbon-containing compound. PMID:20390900

  19. Electrochemical promotion of sulfur dioxide catalytic oxidation

    DEFF Research Database (Denmark)

    Petrushina, Irina; Bandur, Viktor; Cappeln, Frederik Vilhelm;

    2000-01-01

    The effect of electrochemical polarization on the catalytic SO2 oxidation in the molten V2O5-K2S2O7 system has been studied using a gold working electrode in the temperature range 400-460 degrees C. A similar experiment has been performed with the industrial catalyst VK-58. The aim of the present...

  20. Catalytic oxidations by vanadium complexes

    OpenAIRE

    Ligtenbarg, A.G J; Hage, R.; Feringa, B. L.

    2003-01-01

    Vanadium haloperoxidases catalyse the oxidation of halides leading to halogenation of substrates or, in the absence of suitable substrates, to oxidation of hydrogen peroxide into singlet oxygen and water. Furthermore, V-haloperoxidases are capable to give enantioselective sulfoxidation under the appropriate conditions. The most interesting model compounds that have been synthesised and studied as bromination catalysts, and catalysts for, i.e. epoxidation, hydroxylation, sulfoxidation and alco...

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

    OpenAIRE

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

    2000-01-01

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

  2. Formaldehyde degradation by catalytic oxidation.

    OpenAIRE

    Shirey, W N; Hall, T. A.; Hanel, E; Sansone, E B

    1981-01-01

    Formaldehyde used for the disinfection of a laminar-flow biological safety cabinet was oxidatively degraded by using a catalyst. This technique reduced the formaldehyde concentration in the cabinet from about 5,000 to about 45 mg/m3 in 8 h. This technique should prove useful in other applications.

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

    DEFF Research Database (Denmark)

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

    1997-01-01

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

  4. Heterogeneous Metal Catalysts for Oxidation Reactions

    Directory of Open Access Journals (Sweden)

    Md. Eaqub Ali

    2014-01-01

    Full Text Available Oxidation reactions may be considered as the heart of chemical synthesis. However, the indiscriminate uses of harsh and corrosive chemicals in this endeavor are threating to the ecosystems, public health, and terrestrial, aquatic, and aerial flora and fauna. Heterogeneous catalysts with various supports are brought to the spotlight because of their excellent capabilities to accelerate the rate of chemical reactions with low cost. They also minimize the use of chemicals in industries and thus are friendly and green to the environment. However, heterogeneous oxidation catalysis are not comprehensively presented in literature. In this short review, we clearly depicted the current state of catalytic oxidation reactions in chemical industries with specific emphasis on heterogeneous catalysts. We outlined here both the synthesis and applications of important oxidation catalysts. We believe it would serve as a reference guide for the selection of oxidation catalysts for both industries and academics.

  5. Deep desulfurization of diesel fuels by catalytic oxidation

    Institute of Scientific and Technical Information of China (English)

    YU Guoxian; CHEN Hui; LU Shanxiang; ZHU Zhongnan

    2007-01-01

    Reaction feed was prepared by dissolving dibenzothiophene (DBT),which was selected as a model organosulfur compound in diesel fuels,in n-octane.The oxidant was a 30 wt-% aqueous solution of hydrogen peroxide.Catalytic performance of the activated carbons with saturation adsorption of DBT was investigated in the presence of formic acid.In addition,the effects of activated carbon dosage,formic acid concentration,initial concentration of hydrogen peroxide,initial concentration of DBT and reaction temperature on the oxidation of DBT were investigated.Experimental results indicated that performic acid and the hydroxyl radicals produced are coupled to oxidize DBT with a conversion ratio of 100%.Catalytic performance of the combination of activated carbon and formic acid is higher than that ofouly formic acid.The concentration of formic acid,activated carbon dosage,initial concentration of hydrogen peroxide and reaction temperature affect the oxidative removal of DBT.The higher the initial concentration of DBT in the n-octane solution,the more difficult the deep desulfurization by oxidation is.

  6. 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.

  7. 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.

  8. Catalytic partial oxidation of pyrolysis oils

    Science.gov (United States)

    Rennard, David Carl

    2009-12-01

    design. Low temperatures are maintained in the fuel delivery system utilizing a water-jacketed nebulizer, which allows for the delivery of bio oil into a furnace at 800°C. The addition of methane to the reactor environment enhances reactor performance, likely by promoting transport of gaseous fuel to the catalyst to sustain reaction. In several configurations, the catalytic partial oxidation of bio oil to syngas is achieved autothermally with contact times of tau = 30 ms. (Abstract shortened by UMI.)

  9. Synthesis and catalytic properties on oxidation reaction of goethite containing niobium; Sintese e propriedades cataliticas em reacoes de oxidacao de goethitas contendo niobio

    Energy Technology Data Exchange (ETDEWEB)

    Oliveira, Luiz C.A.; Goncalves, Maraisa; Oliveira, Diana Q.L.; Guarieiro, Aline L.N. [Universidade Federal de Lavras, MG (Brazil). Dept. de Quimica]. E-mail: luizoliveira@ufla.br; Pereira, Marcio C. [Universidade Federal de Minas Gerais (UFMG), Belo Horizonte, MG (Brazil). Dept. de Quimica

    2007-07-15

    Nb-substituted goethites have been prepared and characterized by Moessbauer spectroscopy, XRD, SEM and BET surface area measurements. Moessbauer and XRD analyses suggested that Nb replaces Fe{sup 3+} in the structure with duplet formation. The insertion of Nb into the goethite structure caused a significant increase in the BET surface area of the material. The prepared {alpha}-Fe{sub 1-x}Nb{sub x}OOH was investigated for the H{sub 2}O{sub 2} decomposition to O{sub 2} and for the Fenton reaction to oxidize the dye methylene blue. It was observed that the introduction of Nb in to goethite produced a strong increase in the activity of oxidation of the dye contaminant by H{sub 2}O{sub 2}. (author)

  10. One-pot synthesis of monodisperse palladium-copper nanocrystals supported on reduced graphene oxide nanosheets with improved catalytic activity and methanol tolerance for oxygen reduction reaction

    Science.gov (United States)

    Lv, Jing-Jing; Li, Shan-Shan; Wang, Ai-Jun; Mei, Li-Ping; Feng, Jiu-Ju; Chen, Jian-Rong; Chen, Zhaojiang

    2014-12-01

    Monodisperse bimetallic alloyed palladium-copper nanocrystals are uniformly supported on reduced graphene oxide nanosheets by a one-pot solvothermal strategy, with an average size of 6.81 nm. As a result, the as-prepared nanocomposites have the enlarged electrochemically active surface area (49.2 m2 g-1), and display the improved electrocatalytic performance and high methanol-tolerance ability for oxygen reduction reaction in alkaline media, compared with commercial Pd black and RGOs. Those RGOs-supporting Pd-Cu alloys would have potential applications in fuel cells.

  11. Oscillatory Behavior during the Catalytic Partial Oxidation of Methane: Following Dynamic Structural Changes of Palladium Using the QEXAFS Technique

    DEFF Research Database (Denmark)

    Stoetzel, Jan; Frahm, Ronald; Kimmerle, Bertram;

    2012-01-01

    Pd/Al2O3 catalysts oscillate between ignition and extinction of the catalytic partial oxidation of methane when they are exposed to a 2:1 reaction mixture of methane and oxygen. The oscillations of the catalytic performance and the structure of Pd/Al2O3 catalysts in a fixed-bed reactor were...... combination of total oxidation and reforming in the catalytic capillary reactor was observed. This change in catalytic performance was directly linked to changes in the oxidation state of the Pd/Al2O3 catalysts at different positions along the catalytic reactor. During the ignition of the catalytic partial...

  12. Catalytic aerobic oxidation of bio-renewable chemicals

    DEFF Research Database (Denmark)

    Gorbanev, Yury

    This thesis covers the investigation of new catalytic systems for the aerobic oxidation of chemicals derived from bio-renewable sources. The effects of different factors and conditions on the reactions were examined. The employed catalysts were characterized by physisorption measurements, SEM, TEM......, EDS, XRF and other methods. Supported gold and ruthenium hydroxide catalyst systems were explored for the aerobic oxidation of 5-hydroxymethylfurfural (HMF) to 2,5-furandicarboxylic acid (FDA), a potential polymer building block for the plastic industry, or its dimethyl ester (FDMC). High product...... selectivities and yields were obtained under optimized conditions. Heterogeneous catalysts consisting of Au nanoparticles on different supports were shown to efficiently oxidize HMF to FDA or FDMC in water or methanol, respectively. Additionally, the reaction conditions were shown to be adjustable...

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

    KAUST Repository

    Wang, Jianfang

    2014-08-26

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

  14. DNA-binding, catalytic oxidation, C—C coupling reactions and antibacterial activities of binuclear Ru(II thiosemicarbazone complexes: Synthesis and spectral characterization

    Directory of Open Access Journals (Sweden)

    Arumugam Manimaran

    2012-07-01

    Full Text Available New hexa-coordinated binuclear Ru(II thiosemicarbazone complexes of the type {[(B(EPh3(COClRu]2L} (where, E = P or As; B = PPh3 or AsPh3 or pyridine; L = mononucleating NS donor of N-substituted thiosemicarbazones have been synthesized and characterized by elemental analysis, FT-IR, UV–vis and 31P{1H} NMR cyclic voltammetric studies. The DNA-binding studies of Ru(II complexes with calf thymus DNA (CT-DNA were investigated by UV–vis, viscosity measurements, gel-electrophoresis and fluorescence spectroscopy. The new complexes have been used as catalysts in C—C coupling reaction and in the oxidation of alcohols to their corresponding carbonyl compounds by using NMO as co-oxidant and molecular oxygen (O2 atmosphere at ambient temperature. Further, the new binucleating thiosemicarbazone ligands and their Ru(II complexes were also screened for their antibacterial activity against Klebsiella pneumoniae, Shigella sp., Micrococcus luteus, Escherichia coli and Salmonella typhi. From this study, it was found out that the activity of the complexes almost reaches the effectiveness of the conventional bacteriocide.

  15. Catalytic and surface oxidation processes on transition metal surfaces

    OpenAIRE

    Jaatinen, Sampsa

    2007-01-01

    Transition metals are technologically important catalytic materials. The transition metal catalysts are used for example in petroleum and fertilizer industry. In the car industry the catalytic materials are used in the catalytic converters. Because of the industrial importance the catalytic metals have been widely studied throughout the past decades. Nonetheless, the oxidation mechanisms of small molecules and the effect of alloying to catalytic properties of metals are not fully understood. ...

  16. Effect the conditions of the acid-thermal modification of clinoptilolite have on the catalytic properties of palladium-copper complexes anchored on it in the reaction of carbon monoxide oxidation

    Science.gov (United States)

    Rakitskaya, T. L.; Kiose, T. A.; Ennan, A. A.; Golubchik, K. O.; Oleksenko, L. P.; Gerasiova, V. G.

    2016-06-01

    The dependence of the physicochemical and structural-adsorption properties of natural and acid-thermal modified clinoptilolite, and of Pd(II)-Cu(II) catalysts based on them, on the duration of acid-thermal modification is investigated. The samples under study are described via XRD and thermal gravimetric (DTG and DTA) analysis, IR, DR UV-Vis, EPR spectroscopy, and water vapor adsorption. Values of both the specific surface area ( S sp) and pH of aqueous suspensions are determined. The resulting catalysts are tested in the reaction of low-temperature carbon monoxide oxidation with air oxygen. A conclusion is drawn about the nature of surface bimetallic Pd(II)-Cu(II) complexes. The greatest catalytic activity is shown by complexes based on clinoptilolite and modified with 3 M HNO3 for 0.5 and 1 h.

  17. Solid State, Surface and Catalytic Studies of Oxides

    Energy Technology Data Exchange (ETDEWEB)

    Kung, H. H.

    2004-11-23

    This project investigates the catalytic properties of oxides for the selective oxidative dehydrogenation of light alkanes and for hydrocarbon reduction of NO{sub x}. Various vanadium oxide based catalysts were investigated to elucidate the relationship between the chemical and structural properties of the catalysts and their selectivity for the formation of alkenes. It was found that vanadium oxide units that are less reducible give higher selectivities. For hydrocarbon reduction of NO{sub x}, it was found that alumina-based catalysts can be effective at higher temperatures than the corresponding zeolite-based catalysts. On some catalysts, such as SnO{sub 2}/Al{sub 2}O{sub 3}. Ag/Al{sub 2}O{sub 3}, the alumina participates directly in the reaction, making the catalyst bifunctional. These results are useful in research to improve the performance of this stress of catalysts.

  18. Fundamental studies of the mechanism of catalytic reactions with catalysts effective in the gasification of carbon solids and the oxidative coupling of methane. Quarterly report, April 1, 1994--June 30, 1994

    Energy Technology Data Exchange (ETDEWEB)

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

    1994-06-01

    Catalytic gasification work has been completed and no other work is planned in the general area of catalytic gasification of coals and chars has operated without a post-doctoral fellow because of budget limitations during the first two quarters of FY1994. Dr. S. Sundararajan joined the group in April 1994 and will be assigned to the project throughout the remaining of the fiscal year. Results published by Hamakawa, et al. in The Journal of the Electrochemical Society have confirmed the concept of methane coupling via a membrane reactor. These findings confirm our previous conclusion that thinner membranes and increased surface activity for C-H bond activation at low temperatures are required in order to reach commercially attractive rates of reaction. The initial analysis of a theoretical model comparing the membrane and cyclic processes has been completed. The results indicate that perovskite membranes on the order of 50 microns will be needed for the membrane operation to be superior to a cyclic one. Two techniques, laser ablation and spin-coating/sol-gel chemistry are being tried to prepare the thin membranes described above. Studies of the magnetochemical properties of the calcium-nickel-potassium oxide powdered catalysts have been concluded and a manuscript describing the work has been completed. Synchrotron x-ray fluorescence microprobe data for calcium-nickel-potassium films have been analyzed and an abstract of the results has been submitted for presentation at the Fall Meeting of the Materials Research Society. Initial films of strontium-zirconium oxide, using yttria-stabilized zirconia as a buffer layer, have been fabricated using pulsed laser deposition. X-ray diffraction data have been obtained for several of the strontium-zirconium-yttrium oxide films.

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

    Directory of Open Access Journals (Sweden)

    B. A. López de Mishima

    2000-03-01

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

  20. Kinetics study on catalytic wet air oxidation of phenol by several metal oxide catalysts

    Institute of Scientific and Technical Information of China (English)

    WAN Jia-feng; FENG Yu-jie; CAI Wei-min; YANG Shao-xia; SUN Xiao-jun

    2004-01-01

    Four metal oxide catalysts composed of copper (Cu), stannum (Sn), copper-stannum (Cu-Sn) and copper-cerium(Cu-Ce) respectively were prepared by the co-impregnation method, and γ-alumina(γ-Al2O3) is selected as support. A first-order kinetics model was established to study the catalytic wet air oxidation of phenol at different temperature when these catalysts were used. The model simulations are good agreement with present experimental data. Results showed that the reaction rate constants can be significantly increased when catalysts were used, and the catalyst of 6% Cu-10%Ce/γ-Al2O3 showed the best catalytic activity. This is consistent with the result of catalytic wet air oxidation of phenol and the COD removal can be arrived at 98.2% at temperature 210℃, oxygen partial pressure 3 MPa and reaction time 30 min. The activation energies of each reaction with different catalysts are nearly equal, which is found to be about 42 kJ/mol and the reaction in this study is proved to be kinetics control.

  1. Catalytic and non-catalytic wet air oxidation of sodium dodecylbenzene sulfonate: kinetics and biodegradability enhancement.

    Science.gov (United States)

    Suárez-Ojeda, María Eugenia; Kim, Jungkwon; Carrera, Julián; Metcalfe, Ian S; Font, Josep

    2007-06-18

    Wet air oxidation (WAO) and catalytic wet air oxidation (CWAO) were investigated as suitable precursors for the biological treatment of industrial wastewater containing sodium dodecylbenzene sulfonate (DBS). Two hours WAO semi-batch experiments were conducted at 15 bar of oxygen partial pressure (P(O2)) and at 180, 200 and 220 degrees C. It was found that the highest temperature provides appreciable total organic carbon (TOC) and chemical oxygen demand (COD) abatement of about 42 and 47%, correspondingly. Based on the main identified intermediates (acetic acid and sulfobenzoic acid) a reaction pathway for DBS and a kinetic model in WAO were proposed. In the case of CWAO experiments, seventy-two hours tests were done in a fixed bed reactor in continuous trickle flow regime, using a commercial activated carbon (AC) as catalyst. The temperature and P(O2) were 140-160 degrees C and 2-9 bar, respectively. The influence of the operating conditions on the DBS oxidation, the occurrence of oxidative coupling reactions over the AC, and the catalytic activity (in terms of substrate removal) were established. The results show that the AC without any supported active metal behaves bi-functional as adsorbent and catalyst, giving TOC conversions up to 52% at 160 degrees C and 2 bar of P(O2), which were comparable to those obtained in WAO experiments. Respirometric tests were completed before and after CWAO and to the main intermediates identified through the WAO and CWAO oxidation route. Then, the readily biodegradable COD (COD(RB)) of the CWAO and WAO effluents were found. Taking into account these results it was possible to compare whether or not the CWAO or WAO effluents were suitable for a conventional activated sludge plant inoculated with non adapted culture. PMID:17363148

  2. Catalytic and non-catalytic wet air oxidation of sodium dodecylbenzene sulfonate: Kinetics and biodegradability enhancement

    International Nuclear Information System (INIS)

    Wet air oxidation (WAO) and catalytic wet air oxidation (CWAO) were investigated as suitable precursors for the biological treatment of industrial wastewater containing sodium dodecylbenzene sulfonate (DBS). Two hours WAO semi-batch experiments were conducted at 15bar of oxygen partial pressure (PO2) and at 180, 200 and 220deg. C. It was found that the highest temperature provides appreciable total organic carbon (TOC) and chemical oxygen demand (COD) abatement of about 42 and 47%, correspondingly. Based on the main identified intermediates (acetic acid and sulfobenzoic acid) a reaction pathway for DBS and a kinetic model in WAO were proposed. In the case of CWAO experiments, seventy-two hours tests were done in a fixed bed reactor in continuous trickle flow regime, using a commercial activated carbon (AC) as catalyst. The temperature and PO2 were 140-160deg. C and 2-9bar, respectively. The influence of the operating conditions on the DBS oxidation, the occurrence of oxidative coupling reactions over the AC, and the catalytic activity (in terms of substrate removal) were established. The results show that the AC without any supported active metal behaves bi-functional as adsorbent and catalyst, giving TOC conversions up to 52% at 160deg. C and 2 bar of PO2, which were comparable to those obtained in WAO experiments. Respirometric tests were completed before and after CWAO and to the main intermediates identified through the WAO and CWAO oxidation route. Then, the readily biodegradable COD (CODRB) of the CWAO and WAO effluents were found. Taking into account these results it was possible to compare whether or not the CWAO or WAO effluents were suitable for a conventional activated sludge plant inoculated with non adapted culture

  3. Catalytic and non-catalytic wet air oxidation of sodium dodecylbenzene sulfonate: Kinetics and biodegradability enhancement

    Energy Technology Data Exchange (ETDEWEB)

    Suarez-Ojeda, Maria Eugenia [Departament d' Enginyeria Quimica, Escola Tecnica Superior d' Enginyeria Quimica, Universitat Rovira i Virgili, Av. Paisos Catalans 26, 43007 Tarragona, Catalonia (Spain); Departament d' Enginyeria Quimica, Edifici Q-ETSE, Universitat Autonoma de Barcelona, 08193 Bellaterra, Barcelona, Catalonia (Spain); Kim, Jungkwon [Chemical Engineering and Analytical Sciences Department, University of Manchester, Manchester (United Kingdom); Carrera, Julian [Departament d' Enginyeria Quimica, Edifici Q-ETSE, Universitat Autonoma de Barcelona, 08193 Bellaterra, Barcelona, Catalonia (Spain); Metcalfe, Ian S. [Chemical Engineering and Advanced Materials Department, University of Newcastle upon Tyne, Newcastle upon Tyne (United Kingdom); Font, Josep [Departament d' Enginyeria Quimica, Escola Tecnica Superior d' Enginyeria Quimica, Universitat Rovira i Virgili, Av. Paisos Catalans 26, 43007 Tarragona, Catalonia (Spain)]. E-mail: jose.font@urv.cat

    2007-06-18

    Wet air oxidation (WAO) and catalytic wet air oxidation (CWAO) were investigated as suitable precursors for the biological treatment of industrial wastewater containing sodium dodecylbenzene sulfonate (DBS). Two hours WAO semi-batch experiments were conducted at 15bar of oxygen partial pressure (P{sub O{sub 2}}) and at 180, 200 and 220deg. C. It was found that the highest temperature provides appreciable total organic carbon (TOC) and chemical oxygen demand (COD) abatement of about 42 and 47%, correspondingly. Based on the main identified intermediates (acetic acid and sulfobenzoic acid) a reaction pathway for DBS and a kinetic model in WAO were proposed. In the case of CWAO experiments, seventy-two hours tests were done in a fixed bed reactor in continuous trickle flow regime, using a commercial activated carbon (AC) as catalyst. The temperature and P{sub O{sub 2}} were 140-160deg. C and 2-9bar, respectively. The influence of the operating conditions on the DBS oxidation, the occurrence of oxidative coupling reactions over the AC, and the catalytic activity (in terms of substrate removal) were established. The results show that the AC without any supported active metal behaves bi-functional as adsorbent and catalyst, giving TOC conversions up to 52% at 160deg. C and 2 bar of P{sub O{sub 2}}, which were comparable to those obtained in WAO experiments. Respirometric tests were completed before and after CWAO and to the main intermediates identified through the WAO and CWAO oxidation route. Then, the readily biodegradable COD (COD{sub RB}) of the CWAO and WAO effluents were found. Taking into account these results it was possible to compare whether or not the CWAO or WAO effluents were suitable for a conventional activated sludge plant inoculated with non adapted culture.

  4. Catalytic oxidation of carbon monoxide over supported palladium nanoparticles

    Science.gov (United States)

    Soni, Keshav Chand; Krishna, R.; Chandra Shekar, S.; Singh, Beer

    2016-01-01

    Catalytic oxidation of CO with ozone had been studied over Al2O3 and SiO2 supported Pd nanoparticles which was synthesized by two different methods. The polyol method mainly resulted in highly dispersed Pd particles on the support, while the impregnation method resulted in agglomeration Pd particles on the support. Supported Pd nanoparticles synthesized from PdCl2 in the presence of poly ( N-vinylpyrrolidone) (PVP) by chemical reduction. The catalysts were characterized by X-ray diffraction, N2 BET surface area, pore size distributions, CO chemisorption, TEM and H2-temperature programmed reduction. The physico-chemical properties were well correlated with activity data. Characterizations of XRD and TEM show that the surface Pd nanoparticles are highly dispersed over Al2O3 and SiO2. The catalytic activity was dependent upon ozone/CO ratio, contact times, and the reaction temperature. The extent of carbon monoxide oxidation was proportional to the catalytically ozone decomposition. The PVP synthesized Pd/A2O3 catalyst had been found to be highly active for complete CO removal at room temperature. The higher activity of the nanocatalyst was attributed to small particle size and higher dispersion of Pd over support.

  5. Catalytic Conversion of Methanol by Oxidative Dehydrogenation

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    This study investigates the effects of addition of oxygen on the oxidative dehydrogenation (ODH) of methanol when a fluorotetrasilicic mica ion-exchanged with palladium (Pd2+-TSM) was used as the catalyst. The reaction proceeded at a very low temperature in the presence of oxygen, and HCOOCH3 was obtained at high selectivity. By calculating the equilibrium conversion, it has been shown that substantial ODH took place for HCOOCH3 production. Consequently, this reaction would make dehydrogenation the dominant reaction at equilibrium. Not all the H dissociated from CH3OH was converted to H2O by oxidation. It has been shown that the H2O was not produced from oxidative dehydrogenation by the direct reaction of CH3OH and O2 when an attempt was made to carry out oxidative dehydrogenation using an isotope oxygen trace method in the gas phase. Therefore, when CH3OH was converted to CO2 and dehydrogenated to HCOOCH3, the C-O bonds were not dissociated.

  6. Rapid and facile preparation of zinc ferrite (ZnFe{sub 2}O{sub 4}) oxide by microwave-solvothermal technique and its catalytic activity in heterogeneous photo-Fenton reaction

    Energy Technology Data Exchange (ETDEWEB)

    Anchieta, Chayene G.; Severo, Eric C.; Rigo, Caroline; Mazutti, Marcio A. [Department of Chemical Engineering, Federal University of Santa Maria, 97105-900, Santa Maria (Brazil); Kuhn, Raquel C., E-mail: raquelckuhn@yahoo.com.br [Department of Chemical Engineering, Federal University of Santa Maria, 97105-900, Santa Maria (Brazil); Muller, Edson I.; Flores, Erico M.M. [Department of Chemistry, Federal University of Santa Maria, 97105-900, Santa Maria (Brazil); Moreira, Regina F.P.M. [Department of Chemical Engineering and Food Engineering, Federal University of Santa Catarina, 88040-970, Florianópolis (Brazil); Foletto, Edson L. [Department of Chemical Engineering, Federal University of Santa Maria, 97105-900, Santa Maria (Brazil)

    2015-06-15

    In this work zinc ferrite (ZnFe{sub 2}O{sub 4}) oxide was rapidly and easily prepared by microwave-solvothermal route and its catalytic property in photo-Fenton reaction was evaluated. The effects of microwave heating time and power on the properties of produced particles were investigated. X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), atomic force microscopy (AFM) and nitrogen adsorption–desorption isotherms were the techniques used for characterizing the solid products. The synthesized material was tested as a catalyst in the degradation of the textile dye molecule by the heterogeneous photo-Fenton process. Characterization results showed that the microwave heating time and power have significant influences on the formation of the phase spinel as well as on its physical properties. The reaction results showed that the ZnFe{sub 2}O{sub 4} oxide has good photocatalytic activity, which can be attributed to high surface area and pore volume, and large pore size. The ZnFe{sub 2}O{sub 4} oxide produced by the microwave irradiation exhibited promising photocatalytic activity for the removal of textile dye, reaching nearly 100% of decolorization at 40 min and 60% of mineralization at 240 min. Therefore, ZnFe{sub 2}O{sub 4} particles rapidly prepared by the microwave route have the potential for use in treatment of textile wastewater by the heterogeneous photo-Fenton process. - Highlights: • ZnFe{sub 2}O{sub 4} was synthesized by microwave-solvothermal method. • ZnFe{sub 2}O{sub 4} was prepared by different microwave heating times and powers. • ZnFe{sub 2}O{sub 4} was used as heterogeneous photo-Fenton catalyst. • Degradation of Procion red dye using heterogeneous photo-Fenton process. • ZnFe{sub 2}O{sub 4} was highly efficient to degrade textile dye under visible light.

  7. Rapid and facile preparation of zinc ferrite (ZnFe2O4) oxide by microwave-solvothermal technique and its catalytic activity in heterogeneous photo-Fenton reaction

    International Nuclear Information System (INIS)

    In this work zinc ferrite (ZnFe2O4) oxide was rapidly and easily prepared by microwave-solvothermal route and its catalytic property in photo-Fenton reaction was evaluated. The effects of microwave heating time and power on the properties of produced particles were investigated. X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), atomic force microscopy (AFM) and nitrogen adsorption–desorption isotherms were the techniques used for characterizing the solid products. The synthesized material was tested as a catalyst in the degradation of the textile dye molecule by the heterogeneous photo-Fenton process. Characterization results showed that the microwave heating time and power have significant influences on the formation of the phase spinel as well as on its physical properties. The reaction results showed that the ZnFe2O4 oxide has good photocatalytic activity, which can be attributed to high surface area and pore volume, and large pore size. The ZnFe2O4 oxide produced by the microwave irradiation exhibited promising photocatalytic activity for the removal of textile dye, reaching nearly 100% of decolorization at 40 min and 60% of mineralization at 240 min. Therefore, ZnFe2O4 particles rapidly prepared by the microwave route have the potential for use in treatment of textile wastewater by the heterogeneous photo-Fenton process. - Highlights: • ZnFe2O4 was synthesized by microwave-solvothermal method. • ZnFe2O4 was prepared by different microwave heating times and powers. • ZnFe2O4 was used as heterogeneous photo-Fenton catalyst. • Degradation of Procion red dye using heterogeneous photo-Fenton process. • ZnFe2O4 was highly efficient to degrade textile dye under visible light

  8. Atmospheric Pressure Microwave Assisted Heterogeneous Catalytic Reactions

    Directory of Open Access Journals (Sweden)

    Farid Chemat

    2007-07-01

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

  9. Identifying systematic DFT errors in catalytic reactions

    DEFF Research Database (Denmark)

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

    2015-01-01

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

  10. Lignin Valorization using Heterogenous Catalytic Oxidation

    DEFF Research Database (Denmark)

    Melián Rodríguez, Mayra; Shunmugavel, Saravanamurugan; Kegnæs, Søren;

    The research interests in biomass conversion to fuels and chemicals has increased significantly in the last decade in view of current problems such as global warming, high oil prices, food crisis and other geopolitical scenarios. Many different reactions and processes to convert biomass into high......-value products and fuels have been proposed in the literature, giving special attention to the conversion of lignocellulosic biomass, which does not compete with food resources and is widely available as a low cost feedstock 1. Lignocellulose biomass is a complex material composed of three main fractions...... complex so different model compounds are often used to study lignin valorization. These model compounds contain the linkages present in lignin, simplifying catalytic analysis and present analytical challenges related to the study of the complicated lignin polymer and the plethora of products that could be...

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

    Science.gov (United States)

    Rodriguez, JoséA.; Wayne Goodman, D.

    1991-11-01

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

  12. Catalytic asymmetric umpolung reactions of imines.

    Science.gov (United States)

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

    2015-07-23

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

  13. Fundamental studies of the mechanism of catalytic reactions with catalysts effective in the gasification of carbon solids and the oxidative coupling of methane. Quarterly report, October 1--December 31, 1993

    Energy Technology Data Exchange (ETDEWEB)

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

    1993-12-01

    This report covers the time period from October 1 through December 31, 1993. A description of tasks for fiscal year 1994 is included in this report. Highlights and progress of work performed during this quarter is reported in (a) catalytic steam gasification of coals and cokes; (b) oxidative coupling of methane; and (c) synthesis and characterization of catalysts. Attached to this report is a copy of a manuscript submitted to Proceeding of Fuels Technology Contractors Meeting {open_quotes}Steady-State and Transient Catalytic Oxidation and Coupling of Methane{close_quotes} by Heinemann, Iglesia, and Perry.

  14. Homogeneous catalytic wet air oxidation for the treatment oftextile wastewaters

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    An extensive series of experiments was carried out in order to identify suitable catalysts to boost the reaction rate of wet air oxidation of real textile wastewaters at relatively mild temperature and pressure. Experimental results indicated that all catalysts tested in this investigation had shown an impressive increase in the initial COD and TOC removal rate as well as the COD and TOC removal levels in two hours reaction. Among all the catalysts tested, copper salts were more effective than the rest. Anions of the salt soluffonsalso played a role in the catalytic process with nitrate ions having better effect than sulfate ions. Hence copper nitrates were more effective than copper sulfates. It was also found that a mixture of salts with different metals performed better than either of the component single salt alone.

  15. Tracer investigations of catalytic reactions of hydrocarbons

    International Nuclear Information System (INIS)

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

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

    International Nuclear Information System (INIS)

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

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

    Science.gov (United States)

    Bezborodov, A M; Zagustina, N A

    2014-01-01

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

  18. Kinetics of catalytic reactions-solutions manual

    CERN Document Server

    Vannice, M Albert

    2008-01-01

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

  19. Graphene-based materials in catalytic wet peroxide oxidation

    OpenAIRE

    Gomes, Helder; Ribeiro, Rui; Pastrana-Martínez, Luisa; Figueiredo, José; Faria, Joaquim; Silva, Adrián

    2014-01-01

    In catalytic wet peroxide oxidation (CWPO),an advanced oxidation process, hydrogen peroxide (H2O2) is decomposed catalytically giving rise to hydroxyl radicals (HO•).These radicals, exhibiting high oxidizing potential, serve as effective and non selective species for the degradation of several organic pollutants in liquid phase. Since the report of Lücking et al. [1], carbon materials have been explored as catalysts for CWPO[2]. Recent reports address process intensification issues, br...

  20. 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)

  1. Catalytic Asymmetric Umpolung Reactions of Imines

    OpenAIRE

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

    2015-01-01

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

  2. Atmospheric Pressure Microwave Assisted Heterogeneous Catalytic Reactions

    Directory of Open Access Journals (Sweden)

    Ken Belmore

    2007-07-01

    Full Text Available The newly synthesized 5,10,15,20-tetra[3-(3-trifluoromethylphenoxy]porphyrin, TTFMPP, has been characterized using mass spectroscopy, 1H-, 13C- and 19F-NMR, MALDI-TOF mass spectrometry, UV-Vis and fluorescence spectrophotometry, andcyclic voltammetry. The NMR confirmed the structure of the compound and the massspectrum was in agreement with the proposed molecular formula. The UV-Vis absorptionspectrum of TTFMPP shows characteristic spectral patterns similar to those of tetraphenylporphryin, with a Soret band at 419 nm and four Q bands at 515, 550, 590, and 648 nm.Protonation of the porphyrin with TFA resulted in the expected red shift of the Soret band.Excitation at 419 nm gave an emission at 650 nm. The quantum yield of the porphyrin wasdetermined to be 0.08. Cyclic voltammetry was used to determine the oxidation andreduction potentials of the new porphyrin. Two quasi-reversible one-electron reductions at–1.00 and –1.32 V and a quasi-reversible oxidation at 1.20 V versus the silver/silverchloride reference electrode with tetrabutylammonium tetrafluoroborate as the supportingelectrolyte in methylene chloride were observed.

  3. Catalytic wet air oxidation for the treatment of emulsifying wastewater

    Institute of Scientific and Technical Information of China (English)

    ZHAO Jian-fu; CHEN Ling; LU Yi-cheng; TANG Wen-wei

    2005-01-01

    The wet air oxidation (WAO) and catalytic WAO (CWAO) of the high strength emulsifying wastewater containing nonionic surfactants have been investigated in terms of COD and TOC removal. The WAO and homogeneous CWAO processes were carried out at the temperature from 433 K to 513 K, with initial oxygen pressure 1.2 MPa. It was found that homogeneous catalyst copper(Cu ( NO3 )2 )had an fairly good catalytic activity for the WAO process, and the oxidation was catalyzed when the temperature was higher than 473 K.Moreover, several heterogeneous catalysts were proved to be effective for the WAO process. At the temperature 473 K, after 2 h reaction,WAO process could achieve about 75% COD removal and 66% TOC removal, while catalysts Cu/Al2O3 and Mn-Ce/Al2O3 elevated the COD removal up to 86%-89% and that of TOC up to 82%. However, complete elimination of COD and TOC was proved to be difficult even the best non-noble catalyst was used. Therefore, the effluent from WAO or CWAO process need to be further disposed. The bioassay proved that the effluent from WAO process was amenable to the biochemical method.

  4. 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.

  5. Metal-Free Oxidation of Primary Amines to Nitriles through Coupled Catalytic Cycles.

    Science.gov (United States)

    Lambert, Kyle M; Bobbitt, James M; Eldirany, Sherif A; Kissane, Liam E; Sheridan, Rose K; Stempel, Zachary D; Sternberg, Francis H; Bailey, William F

    2016-04-01

    Synergism among several intertwined catalytic cycles allows for selective, room temperature oxidation of primary amines to the corresponding nitriles in 85-98 % isolated yield. This metal-free, scalable, operationally simple method employs a catalytic quantity of 4-acetamido-TEMPO (ACT; TEMPO=2,2,6,6-tetramethylpiperidine N-oxide) radical and the inexpensive, environmentally benign triple salt oxone as the terminal oxidant under mild conditions. Simple filtration of the reaction mixture through silica gel affords pure nitrile products. PMID:26868873

  6. Selective catalytic oxidations of alkylaromatic compounds

    Energy Technology Data Exchange (ETDEWEB)

    Fischer, R.W. [Celanese GmbH, Oberhausen (Germany); Roehrscheid, F. [Hoechst AG, Frankfurt am Main (Germany). Zentralforschung und Technologie

    1998-12-31

    Focused to the guidelines of `Sustainable Development` `Responsible Care` and `Customer Satisfaction`, modern production processes are critically assessed on their balance between their ecological benefits and their economical parameters as well as their value to the community. Also in the area of fine chemicals, it is obvious that more and more processes are devolved which save feedstock, reduce emissions and minimize the potential for safety hazards: Less additive but more integrated protection of the environment yielding ecologically highly valuable processes. The described production of aromatic carboxylic acids is an ideal example for such a modern process. Nowadays the synthesis of derivatives of benzoic acid utilizes air as Ideal oxidant and acetic acid as environmental unquestionable solvent. The major byproduct of the oxidation reaction is water in some cases, dependend on the substrate also carbon dioxide. (orig.)

  7. Structure and catalytic reactivity of Rh oxides

    DEFF Research Database (Denmark)

    Gustafson, J.; Westerström, R.; Resta, A.;

    2009-01-01

    as well as on Rh nanoparticles. The detailed structure of this film was previously determined using UHV based techniques and density functional theory. In the present paper, we also examine the structure of the bulk Rh2O3 corundum oxide using surface X-ray diffraction. Being armed with this...... structural information, we have explored the CO oxidation reaction over Rh(1 1 1), Rh(1 0 0) and Pt25Rh75(1 0 0) at realistic pressures using in situ surface X-ray diffraction and online mass spectrometry. In all three cases we find that an increase of the CO2 production coincides with the formation of the...

  8. Catalytic oxidation of CO on Ir(100)

    Energy Technology Data Exchange (ETDEWEB)

    Erikat, I.A. [Department of Physics, Jerash Private University (Jordan); Hamad, B.A.; Khalifeh, J.M. [Department of Physics, University of Jordan, Amman-11942 (Jordan)

    2011-06-15

    Density functional theory (DFT) calculations are performed to investigate the CO oxidation on Ir(100) surface at different CO coverages, 0.125, 0.25, and 0.5 monolayers (ML). The reaction pathway and transition state (TS) are determined using constrained minimization and nudged elastic band (NEB) methods. We found that the CO molecule is significantly more mobile toward O atoms, which causes a weakening of the O-metal bond. The increase of CO coverage leads to a decrease in the activation energy of the reaction and an increase of O{sub a}-CO distance where O coverage is kept at 0.25 ML. (Copyright copyright 2011 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  9. Session 6: The catalytic oxidation of selected chlorinated hydrocarbons

    Energy Technology Data Exchange (ETDEWEB)

    Oszczudlowski, J. [Institute of Chemistry, Swietokrzyska Academy, Kielce (Poland)

    2004-07-01

    The catalytic oxidation of selected chlorinated hydrocarbons was investigated in the presence of natural zeolites modified with 3M HCl and chromium and lanthanum from aqueous solutions. Natural zeolites of the structure of clinoptilolite or mordenite possess unique physical and chemical properties such as high sorptive capacity and ion-exchange selectivity, relatively high heat and mechanical resistance. The activation of samples of natural zeolites was carried out in a 3M aqueous solution of HCl using a Soxhlet apparatus, whereas the ion exchange from aqueous solutions of chromium (III) and lanthanum (III) nitrates. Samples of activated zeolites were calcinated at 500 C with a programmable temperature increase within 4 hours The amounts of Cr and La on zeolite were 3,0 % wt and 4,5 % wt, respectively. Catalytic tests were conducted in a micro-reactor coupled with a gas chromatograph. The conditions of reaction were as follows: temperature range: 473-723 K, substrate composition: chlorinated hydrocarbon (1000-10000 ppm), steam (0-10000 ppm) and air. Under standard conditions volatile chlorinated hydrocarbons were introduced into a gas flux as vapours, whereas low-volatile ones in a mixture with n-hexane or cyclohexane. The quantity of the deposits on the surface of a catalyst was analysed by the thermogravimetric and GC-MS methods. The composition of oxidation products of chlorinated hydrocarbons was chromatographically analysed indirectly with the techniques SPME-GC-ECD and SPME-GCFID. The total quantity of the products was stored in gas containers-Tedlars and the quantitative and qualitative composition was analysed by the method SPME-HS-GC-ECD (solid phase micro-extraction-headspace-gas chromatography-electron capture detector). The total oxidation of CCl{sub 4} and C{sub 2}Cl{sub 6} in the presence of the Cr/zeolite catalyst occurs at 400 C. The conversion of the catalytic oxidation of chloro-olefins in the presence of the La/zeolite catalyst increases within

  10. Catalytic Potential of Nano-Magnesium Oxide on Degradation of Humic Acids From Aquatic Solutions

    Directory of Open Access Journals (Sweden)

    Ghorban Asgari

    2014-12-01

    Full Text Available Catalytic ozonation is a new and promising process used to remove the contaminants from drinking water and wastewater. This study aimed to evaluate the catalytic potential of nano-magnesium oxide (nano-MgO for the removal of humic acids (HA from water. Mg (NO32 solution was used to prepare MgO powder by the calcination method. In a semi-batch reactor, the catalytic ozonation was carried out. The effects of the various operating parameters, including pH, reaction time, T-butyl alcohol (TBA and phosphate on HA degradation were evaluated. Experimental results indicated that degradation of HA was increased as the pH solution and reaction time were increased. Maximum HA degradation was obtained at pH = 10 and the reaction time of 10 minutes in the catalytic process. The calculated catalytic potential of nano-MgO on ozonation of HA was 60%. Moreover, catalytic ozonation process was not affected by TBA and the main reaction on HA degradation HA have effect take place on MgO surface. According to the results of this study, the developed MgO catalyst is the active and proficient catalyst in HA degradation using the catalytic ozonation process.

  11. Catalytic oxidation of tritium in air at ambient temperature

    International Nuclear Information System (INIS)

    Tritium/air oxidation kinetic data are derived from ambient-temperature measurements carried out with three precious-metal catalysts. Each catalyst consists of a high-surface-area substrate in pelletized form, onto which precious metal has been dispersed. The metal/substrate combinations investigated are platinum/alumina, palladium/kaolin, and palladium/zeolite. Electron-microprobe scans reveal that the dispersed metal is deposited in each case near the outer surface of the pellet, with metal concentration decreasing exponentially from the pellet surface. Kinetic oxidation measurements are made in a unique apparatus consisting of a large Lucite enclosure with an air atmosphere processed by a recirculating cleanup system. Dual-ionization chambers with an intermediate adsorption bed permit measurement of tritium gas and tritiated water vapor. Rate coefficients are determined from concentration decay following a spike injection of tritium into the enclosure. The catalytic reaction is first-order in tritium concentration in the range 10 to 105 μCi/m3. Addition of hydrogen carrier gas is unnecessary. Each of the dispersed-metal catalysts is extremely active in promoting tritium oxidation in comparison with self-catalyzed atmospheric conversion; equivalent first-order rate constants are higher by roughly 9 orders of magnitude. The platinum-based catalyst is more effective than the palladium catalysts on a surface-area basis by about a factor of 3. Catalytic activity for all three catalysts declines with time of exposure to air after activation, following a power-law decay with an exponent of -1/2. A model for optimization of the catalyst reactivation cycle is proposed, revealing that the optimum catalyst volume scales with flow rate to the 2/3 power. Ambient-temperature tritium oxidation is cost-effective for small- to intermediate-scale cleanup systems. A heated catalyst is desirable for large-scale systems

  12. Selective catalytic oxidation of H2S over iron oxide supported on alumina-intercalated Laponite clay catalysts

    International Nuclear Information System (INIS)

    Graphical abstract: The catalytic reaction and deactivation mechanisms for H2S selective oxidation over Fe/Al-Lap catalysts are shown in the illustration. The catalytic reaction follows Mars–van Krevelen mechanism. Moreover, the interaction between iron oxide and alumina, the strong acidity of the catalysts and the well dispersion of iron oxide improve the catalytic performance efficiently. Meanwhile, the catalyst deactivation is mainly due to the formation of Fe2(SO4)3 and elemental sulfur deposits on the surface. -- Highlights: • Fe/Al-Lap catalysts with mesoporous structure were synthesized. • Iron oxide mainly exists in form of isolate Fe3+ in an oxidic environment. •Fe/Al-Lap catalysts show high catalytic activities at low temperature. •The high catalytic activities are ascribed to the interaction between iron oxide and alumina. •The formed Fe2(SO4)3 and elemental sulfur deposits on surface cause catalyst deactivation. -- Abstract: A series of iron oxide supported on alumina-intercalated clay catalysts (named Fe/Al-Lap catalysts) with mesoporous structure and high specific surface area were prepared. The structural and chemical properties were studied by nitrogen sorption isotherms, X-ray diffraction (XRD), UV–vis diffuse reflectance spectra (UV–vis DRS), X-ray photoelectron spectra (XPS), Fourier transform infrared spectroscopy (FTIR), H2 temperature-programmed reduction (H2-TPR) and NH3 temperature-programmed desorption (NH3-TPD) techniques. It was realized that iron oxide mainly existed in the form of isolated Fe3+ in an oxidic environment. Fe/Al-Lap catalysts showed high catalytic activities in the temperature range of 120–200 °C without the presence of excessive O2. This can be attributed to the interaction between iron oxide and alumina, which improve the redox property of Fe3+ efficiently. In addition, the strong acidity of catalysts and good dispersion of iron oxide were also beneficial to oxidation reaction. Among them, 7% Fe

  13. CO catalytic oxidation on iron-embedded monolayer MoS2

    International Nuclear Information System (INIS)

    Highlights: • CO catalytic oxidation on the Fe-embedded monolayer MoS2 has been studied. • Fe atom can be strongly constrained at the S vacancy of monolayer MoS2. • Fe-embedded monolayer MoS2 shows high catalytic activity toward CO oxidation. - Abstract: Based on first-principles calculations, the CO catalytic oxidation on the Fe-embedded monolayer MoS2 (Fe-MoS2) was investigated. It is found that Fe atom can be strongly constrained at the S vacancy of monolayer MoS2 with a high diffusion barrier. The CO oxidation reaction proceeds via a two-step mechanism with the highest energy barrier of 0.51 eV, which is started by the Langmuir–Hinshelwood reaction and ended by the Eley–Rideal reaction. The high catalytic activity of the Fe-MoS2 system may be attributed to the charge transfer and the orbital hybridization between the adsorbates and the Fe atom. This study proposes that embedding transition-metals is a promising way for making the basal plane of monolayer MoS2 catalytically active

  14. CO catalytic oxidation on iron-embedded monolayer MoS{sub 2}

    Energy Technology Data Exchange (ETDEWEB)

    Ma, Dongwei, E-mail: dwmachina@126.com [School of Physics, Anyang Normal University, Anyang, Henan 455000 (China); Tang, Yanan [Department of Physics and Electronic Science, Zhengzhou Normal University, Zhengzhou, Henan 450044 (China); Yang, Gui; Zeng, Jun [School of Physics, Anyang Normal University, Anyang, Henan 455000 (China); He, Chaozheng [Physics and Electronic Engineering College, Nanyang Normal University, Nanyang 473061 (China); Lu, Zhansheng [College of Physics and Electronic Engineering, Henan Normal University, Xinxiang, Henan 453007 (China)

    2015-02-15

    Highlights: • CO catalytic oxidation on the Fe-embedded monolayer MoS{sub 2} has been studied. • Fe atom can be strongly constrained at the S vacancy of monolayer MoS{sub 2}. • Fe-embedded monolayer MoS{sub 2} shows high catalytic activity toward CO oxidation. - Abstract: Based on first-principles calculations, the CO catalytic oxidation on the Fe-embedded monolayer MoS{sub 2} (Fe-MoS{sub 2}) was investigated. It is found that Fe atom can be strongly constrained at the S vacancy of monolayer MoS{sub 2} with a high diffusion barrier. The CO oxidation reaction proceeds via a two-step mechanism with the highest energy barrier of 0.51 eV, which is started by the Langmuir–Hinshelwood reaction and ended by the Eley–Rideal reaction. The high catalytic activity of the Fe-MoS{sub 2} system may be attributed to the charge transfer and the orbital hybridization between the adsorbates and the Fe atom. This study proposes that embedding transition-metals is a promising way for making the basal plane of monolayer MoS{sub 2} catalytically active.

  15. Structural, electrical and catalytic properties of ion-implanted oxides

    OpenAIRE

    Hassel, van, E Edwin; Burggraaf, A.J.

    1989-01-01

    The potential application of ion implantation to modify the surfaces of ceramic materials is discussed. Changes in the chemical composition and microstructure result in important variations of the electrical and catalytic properties of oxides.

  16. 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.

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

    Institute of Scientific and Technical Information of China (English)

    罗伟平; 刘大为; 孙俊; 邓伟; 盛文兵; 刘强; 郭灿城

    2014-01-01

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

  18. 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. PMID:27413787

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

    Science.gov (United States)

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

    2008-06-01

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

  20. Catalytic oxidation of dithiols by a semisynthetic enzyme

    Energy Technology Data Exchange (ETDEWEB)

    Stewart, K.D.; Radziejewski, C.; Kaiser, E.T.

    1986-06-11

    The semisynthetic enzyme flavopapain (1C), obtained from the alkylation of Cys-25 of papain with 8..cap alpha..-(bromo-acetyl)-10-methylsioalloxazine (1B), was found to be an effective catalysts for the oxidation of dithiols to disulfides. The k/sub 2//K/sub s/ values for the oxidation of d,l-dihydrolipoamide and d,l-dihydrolipoic acid determined from anaerobic single-reaction stopped-flow kinetics were 4400 and 3400 M/sup -1/s/sup -1/, respectively. These values were, respectively, 126 and 200 times larger than the second-order rate constants for oxidation of d,l-dihydrolipoamide and d,l-dihydrolipoic acid by the model flavin 8-acetyl-10-methylisoalloxazine (1A). Under aerobic turnover conditions using the synthetic dye MTT as an electron acceptor, the k/sub cat/ and K/sub m/ values for the oxidation of d,l-dihydrolipoamide by 1C were in approximate agreement with the k/sub 2/ and K/sub s/ values, indicating that the rate-limiting step of the catalytic cycle is substrate oxidation rather than oxidation of dihydroflavopapain. When compared with flavopapains 2C and 3C (obtained as above but by modification with 7..cap alpha..- and 6..cap alpha..-(bromoacetyl)-10-methylisoalloxazine (2B and 3B, respectively)), flavopapain 1C is the most efficient catalyst. The circular dichroic spectra of flavopapains 1C, 2C, and 3C were recorded, and the dissociation constants of the sulfite addition complexes of 1C and 2C were determined.

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

    Science.gov (United States)

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

    2007-01-01

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

  2. Catalytic wet air oxidation of chlorophenols over supported ruthenium catalysts

    Energy Technology Data Exchange (ETDEWEB)

    Li Ning [Institut de recherches sur la catalyse et l' environnement de Lyon (IRCELYON), UMR 5256, CNRS/Universite Claude Bernard Lyon 1, 2 Avenue Albert Einstein, 69626 Villeurbanne Cedex (France); Descorme, Claude [Institut de recherches sur la catalyse et l' environnement de Lyon (IRCELYON), UMR 5256, CNRS/Universite Claude Bernard Lyon 1, 2 Avenue Albert Einstein, 69626 Villeurbanne Cedex (France)]. E-mail: claude.descorme@catalyse.cnrs.fr; Besson, Michele [Institut de recherches sur la catalyse et l' environnement de Lyon (IRCELYON), UMR 5256, CNRS/Universite Claude Bernard Lyon 1, 2 Avenue Albert Einstein, 69626 Villeurbanne Cedex (France)

    2007-07-31

    A series of noble metal (Pt, Pd, Ru) loaded zirconia catalysts were evaluated in the catalytic wet air oxidation (CWAO) of mono-chlorophenols (2-CP, 3-CP, 4-CP) under relatively mild reaction conditions. Among the investigated noble metals, Ru appeared to be the best to promote the CWAO of CPs as far as incipient-wetness impregnation was used to prepare all the catalysts. The position of the chlorine substitution on the aromatic ring was also shown to have a significant effect on the CP reactivity in the CWAO over 3 wt.% Ru/ZrO{sub 2}. 2-CP was relatively easier to degradate compared to 3-CP and 4-CP. One reason could be the higher adsorption of 2-CP on the catalyst surface. Further investigations suggested that 3 wt.% Ru/ZrO{sub 2} is a very efficient catalyst in the CWAO of 2-CP as far as high 2-CP conversion and TOC abatement could still be reached at even lower temperature (393 K) and lower total pressure (3 MPa). Additionally, the conversion of 2-CP was demonstrated to increase with the initial pH of the 2-CP solution. The dechlorination reaction is promoted at higher pH. In all cases, the adsorption of the reactants and the reaction intermediates was shown to play a major role. All parameters that would control the molecule speciation in solution or the catalyst surface properties would have a key effect.

  3. Structure and reactivity of surface oxides on Pt(110) during catalytic CO oxidation

    OpenAIRE

    Ackermann, M. D.; Pedersen, T. M.; Hendriksen, B.L.M.; ROBACH, O.; Bobaru, S. C.; Quiros, C.; Kim, H.; Hammer, B; Ferrer Fàbregas, Salvador; Frenke, J. W. M.

    2005-01-01

    We present the first structure determination by surface x-ray diffraction during the restructuring of a model catalyst under reaction conditions, i.e., at high pressure and high temperature, and correlate the restructuring with a change in catalytic activity. We have analyzed the Pt(110) surface during CO oxidation at pressures up to 0.5 bar and temperatures up to 625 K. Depending on the O2/CO pressure ratio, we find three well-defined structures: namely, (i) the bulk-terminated Pt(110) surfa...

  4. Electro-catalytic oxidation of ethanol on platinum-iridium mixtures supported on glassy carbon

    International Nuclear Information System (INIS)

    Electro-catalytic oxidation of ethanol on platinum-iridium mixtures supported on glassy carbon was studied, in acid media at different temperatures and concentrations. During the maturation time of deposited iridium, the surface is covered by an irreversible oxide formation, which affects the behavior of the catalytic mixture. The Pt70 Ir30 and Pt90 Ir10 mixtures seem to be a little more active than the Pt/C electrode at potentials below 800 mV (vs. HRE). In all electrodes appears two reactions: partial ethanol oxidation to produce acetaldehyde (main path of reaction at low temperatures and high electrode coverage with ethanol adsorption residues) and the total oxidation to carbon dioxide which is considerable at potential above 800 mV and it is increased with increasing temperature

  5. Highly Chemical and Regio-selective Catalytic Oxidation with a Novel Manganese Catalyst

    Institute of Scientific and Technical Information of China (English)

    刘斌; 陈怡; 余成志; 沈征武

    2003-01-01

    The chemical selectivity of a novel active manganese compound [Mn2IVμ-O)3(TMTACN)2] (PF6)2 (1) in catalytic oxidation reactions depended on the structure of substrates and 1 was able to catalyze the oxidation of toluene into benzaldehyde and/or benzoic acid under very mild conditions. The following results were obtained: (1) The selectivity of the oxidation depended on the electronic density of double bonds. Reactivity was absent when strong electron-witherawing groups were conjugated with double bonds. (2) Allylic oxidation reactions mostly take place when double bond is present inside a ring system, whilst epoxiclarion reactions occur when the alkene moiety is part of linear chain. (3) In ring systems, the methylene group was more likely to be oxidized than the methyl group on ailylic position. As expected, the C--H bonds at the bridgeheads were unreactive.The secondary hydroxyl groups are more easily to be oxidized than the primary hydroxyl groups.

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

    International Nuclear Information System (INIS)

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

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

    DEFF Research Database (Denmark)

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

    2007-01-01

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

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2014-10-24

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

  9. Heterogeneous selective oxidation of formaldehyde over oxide catalysts. 1. Catalytic properties of H3PMo12O40 and K3PMoO12O40

    International Nuclear Information System (INIS)

    Catalytic properties of H3PMo12O40 and K3PMo12O40, dried at 120 deg C and calcinated at 420 deg C, were investigated in the reaction of heterogenous oxidation of formaldehyde in temperature range 120-180 deg C. It is shown that catalytic properties are determined by heat treatment conditions. Formic acid is the main product of formaldehyde oxidation on dried samples. Samples calcinated at 42 deg C are inactive in reaction of formaldehyde oxidation. It is shown that hydrated forms of H3PMo12O40 and K3PMo12O40 are effective in this reaction. (author)

  10. Catalytic abatement of nitrous oxide from nitric and production

    NARCIS (Netherlands)

    Oonk, J.

    1998-01-01

    Nitric acid production is identified as a main source of nitrous oxide. Options for emission reduction however are not available. TNO and Hydro Agri studied the technological and economic feasibility of catalytic decomposition of nitrous oxide in nitric acid tail-gases. Although in literature promis

  11. Catalytic oxidative cracking of hexane as a route to olefins

    NARCIS (Netherlands)

    Boyadjian, Cassia; Lefferts, Leon; Seshan, K.

    2010-01-01

    Catalytic oxidative cracking of naphtha is conceptually an alternative process to steam cracking. The performance of sol–gel synthesized Li/MgO in oxidative cracking of hexane as a model compound of naphtha, has been studied and compared to that of conventionally prepared catalyst. At a temperature

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

    International Nuclear Information System (INIS)

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

  13. Modifying the catalytic and adsorption properties of metals and oxides

    Science.gov (United States)

    Yagodovskii, V. D.

    2015-11-01

    A new approach to interpreting the effect of promoters (inhibitors) of nonmetals and metals added to a host metal (catalyst) is considered. Theoretical calculations are based on a model of an actual two-dimensional electron gas and adsorbate particles. An equation is derived for the isotherm of induced adsorption on metals and semiconductors with respect to small fillings of θ ~ 0.1-0.15. The applicability of this equation is verified experimentally for metals (Ag, Pd, Cu, Fe, and Ni), graphitized ash, and semiconductor oxides Ta2O5, ZnO, and Ni. The applicability of the theoretical model of promotion is verified by the hydrogenation reaction of CO on ultradispersed nickel powder. The use of plasmachemical surface treatments of metals and oxides, accompanied by an increase in activity and variation in selectivity, are investigated based on the dehydrocyclization reactions of n-hexane and the dehydrogenation and dehydration of alcohols. It is established that such treatments for metals (Pt, Cu, Ni, and Co) raise their activity due to the growth of the number of active centers upon an increase in the activation energy. Applying XPES and XRD methods to metallic catalysts, it is shown that the rise in activity is associated with a change in their surface states (variation in the structural characteristics of metal particles and localization of certain forms of carbon in catalytically active centers). It is shown that plasmachemical treatments also alter their surface composition, surface activity, and raise their activity when used with complex phosphate oxides of the NASICON type. It is shown by the example of conversion of butanol-2 that abrupt variations in selectivity (prevalence of dehydration over dehydrogenation and vice versa) occur, depending on the type of plasma. It is concluded that plasmachemical treatments of metals and ZnO and NiO alter the isosteric heats and entropies of adsorption of isopropanol.

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

    Science.gov (United States)

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

    2016-03-01

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

  15. Removal of nitrogen compounds from gasification gas by selective catalytic or non-catalytic oxidation; Typpiyhdisteiden poisto kaasutuskaasusta selektiivisellae katalyyttisellae ja ei-katalyyttisellae hapetuksella

    Energy Technology Data Exchange (ETDEWEB)

    Leppaelahti, J.; Koljonen, T. [VTT Energy, Espoo (Finland)

    1996-12-01

    In gasification reactive nitrogenous compounds are formed from fuel nitrogen, which may form nitrogen oxides in gas combustion. In fluidized bed gasification the most important nitrogenous compound is ammonia (NH{sub 3}). If ammonia could be decomposed to N{sub 2} already before combustion, the emissions if nitrogen oxides could be reduced significantly. One way of increasing the decomposition rate of NH{sub 3} could be the addition of suitable reactants to the gas, which would react with NH{sub 3} and produce N{sub 2}. The aim of this research is to create basic information, which can be used to develop a new method for removal of nitrogen compounds from gasification gas. The reactions of nitrogen compounds and added reactants are studied in reductive atmosphere in order to find conditions, in which nitrogen compounds can be oxidized selectively to N{sub 2}. The project consists of following subtasks: (1) Selective non-catalytic oxidation (SNCO): Reactions of nitrogen compounds and oxidizers in the gas phase, (2) Selective catalytic oxidation (SCO): Reactions of nitrogen compounds and oxidizers on catalytically active surfaces, (3) Kinetic modelling of experimental results in co-operation with the Combustion Chemistry Research Group of Aabo Akademi University. The most important finding has been that NH{sub 3} can be made to react selectively with the oxidizers even in the presence of large amounts of CO and H{sub 2}. Aluminium oxides were found to be the most effective materials promoting selectivity. (author)

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

    OpenAIRE

    Yan Gong; Lu Lin; Zhipei Yan

    2011-01-01

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

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

    Directory of Open Access Journals (Sweden)

    Yan Gong

    2011-02-01

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

  18. Study of the catalytic activity of mixed non-stoichiometric uranium-thorium oxides in carbon monoxide oxidation

    International Nuclear Information System (INIS)

    The aim of this work has been to study the catalytic properties of non-stoichiometric uranium-thorium oxides having the general formula UxTh1-xO2+y, for the oxidation of carbon monoxide. The preparation of pure, homogeneous, isotropic solids having good structural stability and a surface area as high as possible calls for a strict control of the conditions of preparation of these oxides right from the preparation of 'mother salts': the mixed oxalates UxTh1-x(C2O4)2, 2H2O. A study has been made of their physico-chemical properties (overall and surface chemical constitution, texture, structure, electrical conductivity), as well as of their adsorption properties with respect to gaseous species occurring in the catalytic reaction. This analysis has made it possible to put forward a reaction mechanism based on successive oxidations and reductions of the active surface by the reactants. A study of the reactions kinetics has confirmed the existence of this oxidation-reduction mechanism which only occurs for oxides having a uranium content of above 0.0014. The carbon dioxide produced by the reaction acts as an inhibitor by blocking the sites on which carbon monoxide can be adsorbed. These non-stoichiometric mixed oxides are a particularly clear example of catalysis by oxygen exchange between the solid and the gas phase. (author)

  19. Recent developments in research on catalytic reaction networks

    Directory of Open Access Journals (Sweden)

    Roberto Serra

    2013-09-01

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

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2015-04-15

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

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

    International Nuclear Information System (INIS)

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

  2. Developing a Practical Chiral Toolbox for Asymmetric Catalytic Reactions

    Institute of Scientific and Technical Information of China (English)

    ZHANG; XuMu

    2001-01-01

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

  3. Developing a Practical Chiral Toolbox for Asymmetric Catalytic Reactions

    Institute of Scientific and Technical Information of China (English)

    ZHANG XuMu

    2001-01-01

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

  4. Studies on Nitrogen Oxides Removal Using Plasma Assisted Catalytic Reactor

    Institute of Scientific and Technical Information of China (English)

    V. Ravi; Young Sun Mok; B. S. Rajanikanth; Ho-Chul Kang

    2003-01-01

    An electric discharge plasma reactor combined with a catalytic reactor was studied for removing nitrogen oxides. To understand the combined process thoroughly, discharge plasma and catalytic process were separately studied first, and then the two processes were combined for the study. The plasma reactor was able to oxidize NO to NO2 well although the oxidation rate decreased with temperature. The plasma reactor alone did not reduce the NOx (NO+NO2)level effectively, but the increase in the ratio of NO2 to NO as a result of plasma discharge led to the enhancement of NOx removal efficiency even at lower temperatures over the catalyst surface (V2O5-WOa/TiO2). At a gas temperature of 100℃, the NOx removal efficiency obtained using the combined plasma catalytic process was 88% for an energy input of 36 eV/molecule or 30 J/1.

  5. Catalytic wet Air Oxidation of o-Chlorophenol in Wastewater

    Institute of Scientific and Technical Information of China (English)

    徐新华; 汪大翬

    2003-01-01

    Catalytic wet air oxidation (CWAO) was investigated in laboratory-scale experiments for the treatment of o-chlorophenol in wastewater. Experimental results showed that wet air oxidation (WAO) process in the absence of catalyst was also effective for o-chlorophenol in wastewater treatment. Up to 80% of the initial CODCr was removed by wet air oxidation at 270℃ with twice amount of the required stoichiometric oxygen supply. At temperature of 150℃, the removal rate of CODCr was only 30%. Fe2(SO4)3, CuSO4, Cu(NO3)2 and MnSO4 exhibited high catalytic activity. Higher removal rate of CODCr was obtained by CWAO. More than 96% of the initial CODCr was removed at 270℃ and 84.6%-93.6% of the initial CODCr was removed at 150℃. Mixed catalysts had better catalytic activity for the degradation of o-chlorophenol in wastewater.

  6. SPONTANEOUS CATALYTIC WET AIR OXIDATION DURING PRE-TREATMENT OF HIGH-LEVEL RADIOACTIVE WASTE SLUDGE

    Energy Technology Data Exchange (ETDEWEB)

    Koopman, D.; Herman, C.; Pareizs, J.; Bannochie, C.; Best, D.; Bibler, N.; Fellinger, T.

    2009-10-01

    Savannah River Remediation, LLC (SRR) operates the Defense Waste Processing Facility for the U.S. Department of Energy at the Savannah River Site. This facility immobilizes high-level radioactive waste through vitrification following chemical pretreatment. Catalytic destruction of formate and oxalate ions to carbon dioxide has been observed during qualification testing of non-radioactive analog systems. Carbon dioxide production greatly exceeded hydrogen production, indicating the occurrence of a process other than the catalytic decomposition of formic acid. Statistical modeling was used to relate the new reaction chemistry to partial catalytic wet air oxidation of both formate and oxalate ions driven by the low concentrations of palladium, rhodium, and/or ruthenium in the waste. Variations in process conditions led to increases or decreases in the total oxidative destruction, as well as partially shifting the preferred species undergoing destruction from oxalate ion to formate ion.

  7. Catalytic oxidation of albendazole using molybdenum supported on carbon nanotubes as catalyst

    International Nuclear Information System (INIS)

    The catalytic oxidation reaction of the thioether group (-S-) in the structure to the drug albendazole (C12H15N3O2S) was studied in order to obtain a pharmacologically active molecule known as albendazole sulfoxide. With this purpose, three heterogeneous catalysts were prepared using molybdenum (Mo) as active phase and carbon nanotubes as a multiple-layer catalyst support. The incorporation of the active phase was performed by wet impregnation, with subsequent calcination for 4 hours at 400 oC. For the catalytic oxidation reaction was employed hydrogen peroxide-urea (H2NCONH2·H2O2) as oxidizing agent and methanol (CH3OH) as reaction medium. The textural and morphology characterization of carbon nanoparticles and catalysts was carried out by adsorption-desorption of N2 (BET) and scanning electron microscopy (SEM). The identification and quantification of the reaction products were followed by Fourier transform infrared spectroscopy (FTIR) and high performance liquid chromatography (HPLC), respectively. With the yield, selectivity and conversion higher than 90% after 60 minutes of reaction, albendazole sulphoxide was obtained as major product of oxidation reaction. (author)

  8. Roles of catalytic oxidation in control of vehicle exhaust emissions

    International Nuclear Information System (INIS)

    Catalytic oxidation was initially associated with the early development of catalysis and it subsequently became a part of many industrial processes, so it is not surprising it was used to remove hydrocarbons and CO when it became necessary to control these emissions from cars. Later NOx was reduced in a process involving reduction over a Pt/Rh catalyst followed by air injection in front of a Pt-based oxidation catalyst. If over-reduction of NO to NH3 took place, or if H2S was produced, it was important these undesirable species were converted to NOx and SOx in the catalytic oxidation stage. When exhaust gas composition could be kept stoichiometric hydrocarbons, CO and NOx were simultaneously converted over a single Pt/Rh three-way catalyst (TWC). With modern TWCs car tailpipe emissions can be exceptionally low. NO is not catalytically dissociated to O2 and N2 in the presence of O2, it can only be reduced to N2. Its control from lean-burn gasoline engines involves catalytic oxidation to NO2 and thence nitrate that is stored and periodically reduced to N2 by exhaust gas enrichment. This method is being modified for diesel engines. These engines produce soot, and filtration is being introduced to remove it. The exhaust temperature of heavy-duty diesels is sufficient (250-400oC) for NO to be catalytically oxidised to NO2 over an upstream platinum catalyst that smoothly oxidises soot in the filter. The exhaust gas temperature of passenger car diesels is too low for this to take place all of the time, so trapped soot is periodically burnt in O2 above 550oC. Catalytic oxidation of higher than normal amounts of hydrocarbon and CO over an upstream catalyst is used to give sufficient temperature for soot combustion with O2 to take place. (author)

  9. Fundamental studies of the mechanism of catalytic reactions with catalysts effective in the gasification of carbon solids and the oxidative coupling of methane. Quarterly report, October 1--December 31, 1992

    Energy Technology Data Exchange (ETDEWEB)

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

    1992-12-01

    Work on catalytic steam gasification with chars and coals will be extended from atmospheric to elevated pressures using the newly built pressure unit. The novel finding that coking of petroleum in the presence of small amounts of caustic greatly improves the gasification rates and characteristics of the coke will be extended to chars; in the oxidative coupling of methane over ternary catalysts, emphasis will be placed on low temperature coupling and on the oxidative production of syngas from methane at low temperature. Experimental work will continue on the synthesis of the mixed catalyst, and they will be characterized by a number of techniques, including elemental analyses, x-ray diffraction, and surface area determination.

  10. Heterogeneous selective oxidation of formaldehyde over oxide catalysts. 2. Catalytic properties of V-Ti-oxide catalysts

    International Nuclear Information System (INIS)

    Catalytic properties of V-Ti-O-system and individual oxides V2O5 and TiO2 are investigated in reaction of formaldehyde oxidation within temperature range 120-160 deg C. Formic acid is the main product of formaldehyde oxidation on V2O5 and V-TiO-samples containing more than 5 mass% of V2O5, CO, CO2 and methyl formate form in small amounts. Selectivity with respect to formic acid for samples with 10-75 % V2O5-9025 % TiO2 composition in the conversion range 10-75 % at temperature 120 deg C is constant and comprises 98-93 %. V2O5 has high selectivity but low activity. (author)

  11. 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.

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

    International Nuclear Information System (INIS)

    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, 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 0.9 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

  13. Surface and catalytic properties of doped tin oxide nanoparticles

    Science.gov (United States)

    Wang, Chien-Tsung; Lai, De-Lun; Chen, Miao-Ting

    2010-10-01

    Mixed oxides composed of Zn-Sn, Ti-Sn and V-Sn were prepared by a co-precipitation method and evaluated as catalysts for methanol oxidation in an ambient fixed-bed reactor. Surface analysis by X-ray photoelectron spectroscopy (XPS) revealed an electronic interaction between dopant and Sn atoms in the oxide structure and showed the formation of surface states associated with the dopants. Oxygen vacancies were present on the Zn-doped oxide, and the oxidation of methanol to carbon oxides was favored. The Ti-doped oxide exhibited a favorable selectivity to dimethyl ether, related to the oxygen anions near Ti centers. Vanadium dopants not only dramatically increased the catalytic activity but also promoted the partial oxidation of methanol to formaldehyde. Results demonstrate that the bridging dopant-O-Sn bond acts as active sites and influences product distribution.

  14. Catalytic oxidation of cyclohexane to cyclohexanone and cyclohexanol by tert-butyl hydroperoxide over Pt/oxide catalysts

    Indian Academy of Sciences (India)

    I Rekkab-Hammoumraoui; A Choukchou-Braham; L Pirault-Roy; C Kappenstein

    2011-08-01

    Heterogeneous oxidation of cyclohexane with tertiobutyl hydroperoxide was carried out on Pt/oxide (Al2O3, TiO2 and ZrO2) catalysts in the presence of different solvents (acetic acid and acetonitrile). The catalysts were prepared using Pt(NH3)2(NO2)2 as a precursor and characterized by chemical analysis using the ICP–AES method, XRD, TEM, FTIR and BET surface area determination. The oxidation reaction was carried out at 70°C under atmospheric pressure. The results showed the catalytic performance of Pt/Al2O3 as being very high in terms of turnover frequency.

  15. Catalytic Transfer Hydogenation Reactions for Undergraduate Practical Programs

    Science.gov (United States)

    Hanson, R. W.

    1997-04-01

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

  16. Visualizing the mobility of silver during catalytic soot oxidation

    DEFF Research Database (Denmark)

    Gardini, Diego; Christensen, Jakob M.; Damsgaard, Christian Danvad;

    2016-01-01

    The catalytic activity and mobility of silver nanoparticles used as catalysts in temperature programmed oxidation of soot:silver (1:5 wt:wt) mixtures have been investigated by means of flow reactor experiments and in situ environmental transmission electron microscopy (ETEM). The carbon oxidation...... mobility during the soot oxidation, and this mobility, which increases the soot/catalyst contact, is expected to be an important factor for the lower oxidation temperature. In the intimate tight contact mixture the initial dispersion of the silver particles is greater,,and the onset of mobility occurs at a...

  17. Catalytic soot oxidation over Ce- and Cu-doped hydrotalcites-derived mesoporous mixed oxides.

    Science.gov (United States)

    Wang, Zhongpeng; Wang, Liguo; He, Fang; Jiang, Zheng; Xiao, Tiancun; Zhang, Zhaoliang

    2014-09-01

    Ce- and Cu-doped hydrotalcites derived mixed oxides were prepared through co-precipitation and calcination method, and their catalytic activities for soot oxidation with O2 and O2/NO were investigated. The solids were characterized by XRD, TG-DTG, BET, H2-TPR, in situ FTIR and TPO techniques. All the catalysts precursors showed the typical diffraction patterns of hydrotalcite-like materials having layered structure. The derived mixed oxides exhibited mesoporous properties with specific surface area of 45-160 m2/g. After both Ce and Cu incorporated, mixed crystalline phases of CuO (tenorite), CeO2 (fluorite) and MgAl2O4 (spinel) were formed. As a result, the NO(x) adsorption capacity of this catalyst was largely increased to 201 μmol/g, meanwhile, it was also the most effective to convert NO into NO2 in the sorption process due to the enhanced reducibility. The in situ FTIR spectra revealed that NO(x) were stored mainly as chelating bidentate and monodentate nitrate. The interaction effect between Cu and Ce in the mixed oxide resulted in different NO(x) adsorption behavior. Compared with the non-catalyzed soot oxidation, soot conversion curves over the mixed oxides catalysts shift to low temperature in O2. The presence of NO in the gas phase significantly enhanced the soot oxidation activity with ignition temperature decreased to about 320 degrees C, which is due to NO conversion to NO2 over the catalyst followed by the reaction of NO2 with soot. This explains the cooperative effect of Ce and Cu in the mixed oxide on soot oxidation with high activity and 100% selectivity to CO2 formation. PMID:25924375

  18. Catalytic Partial Oxidation of Biomass/Oil Mixture

    Czech Academy of Sciences Publication Activity Database

    Veselý, Václav; Hanika, Jiří; Tukač, V.; Lederer, J.; Kovač, D.

    2013-01-01

    Roč. 7, č. 10 (2013), s. 1940-1945. ISSN 1934-8983 R&D Projects: GA TA ČR TE01020080; GA MPO 2A-2TP1/024 Institutional support: RVO:67985858 Keywords : hydrocarbon oil * biomass * catalytic partial oxidation Subject RIV: CI - Industrial Chemistry, Chemical Engineering http://www.davidpublishing.com/journals_info.asp?jId=1718#

  19. Trends in the Catalytic CO Oxidation Activity of Nanoparticles

    DEFF Research Database (Denmark)

    Nørskov, Jens Kehlet; Falsig, Hanne; Larsen, Britt Hvolbæk;

    2008-01-01

    Going for gold: Density functional calculations show how gold nanoparticles are more active catalysts for CO oxidation than other metal nanoparticles. The high catalytic activity of nanosized gold clusters at low temperature is found to be related to the ability of low-coordinate metal atoms to a...

  20. Solid Waste Decontamination by Thermal Desorption and Catalytic Oxidation Methods

    Czech Academy of Sciences Publication Activity Database

    Šolcová, Olga; Topka, Pavel; Soukup, Karel; Jirátová, Květa; Váňová, H.; Kaštánek, František

    2014-01-01

    Roč. 68, č. 9 (2014), s. 1279-1282. ISSN 0366-6352 R&D Projects: GA MPO FR-TI1/059 Institutional support: RVO:67985858 Keywords : thermal desorption * catalytic oxidation * soil decontamination Subject RIV: CI - Industrial Chemistry, Chemical Engineering Impact factor: 1.468, year: 2014

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

    Energy Technology Data Exchange (ETDEWEB)

    Somorjai, G.A.

    2009-09-14

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

  2. COAL CONVERSION WASTEWATER TREATMENT BY CATALYTIC OXIDATION IN SUPERCRITICAL WATER; FINAL

    International Nuclear Information System (INIS)

    Wastewaters from coal-conversion processes contain phenolic compounds in appreciable concentrations. These compounds need to be removed so that the water can be discharged or re-used. Catalytic oxidation in supercritical water is one potential means of treating coal-conversion wastewaters, and this project examined the reactions of phenol over different heterogeneous oxidation catalysts in supercritical water. More specifically, we examined the oxidation of phenol over a commercial catalyst and over bulk MnO(sub 2), bulk TiO(sub 2), and CuO supported on Al(sub 2) O(sub 3). We used phenol as the model pollutant because it is ubiquitous in coal-conversion wastewaters and there is a large database for non-catalytic supercritical water oxidation (SCWO) with which we can contrast results from catalytic SCWO. The overall objective of this research project is to obtain the reaction engineering information required to evaluate the utility of catalytic supercritical water oxidation for treating wastes arising from coal conversion processes. All four materials were active for catalytic supercritical water oxidation. Indeed, all four materials produced phenol conversions and CO(sub 2) yields in excess of those obtained from purely homogeneous, uncatalyzed oxidation reactions. The commercial catalyst was so active that we could not reliably measure reaction rates that were not limited by pore diffusion. Therefore, we performed experiments with bulk transition metal oxides. The bulk MnO(sub 2) and TiO(sub 2) catalysts enhance both the phenol disappearance and CO(sub 2) formation rates during SCWO. MnO(sub 2) does not affect the selectivity to CO(sub 2), or to the phenol dimers at a given phenol conversion. However, the selectivities to CO(sub 2) are increased and the selectivities to phenol dimers are decreased in the presence of TiO(sub 2) , which are desirable trends for a catalytic SCWO process. The role of the catalyst appears to be accelerating the rate of formation of

  3. Tunable catalytic properties of bi-functional mixed oxides in ethanol conversion to high value compounds

    Energy Technology Data Exchange (ETDEWEB)

    Ramasamy, Karthikeyan K.; Gray, Michel J.; Job, Heather M.; Smith, Colin D.; Wang, Yong

    2016-04-10

    tA highly versatile ethanol conversion process to selectively generate high value compounds is pre-sented here. By changing the reaction temperature, ethanol can be selectively converted to >C2alcohols/oxygenates or phenolic compounds over hydrotalcite derived bi-functional MgO–Al2O3cata-lyst via complex cascade mechanism. Reaction temperature plays a role in whether aldol condensationor the acetone formation is the path taken in changing the product composition. This article containsthe catalytic activity comparison between the mono-functional and physical mixture counterpart to thehydrotalcite derived mixed oxides and the detailed discussion on the reaction mechanisms.

  4. Catalytic oxidation for treatment of ECLSS and PMMS waste streams. [Process Material Management Systems

    Science.gov (United States)

    Akse, James R.; Thompson, John; Scott, Bryan; Jolly, Clifford; Carter, Donald L.

    1992-01-01

    Catalytic oxidation was added to the baseline multifiltration technology for use on the Space Station Freedom in order to convert low-molecular weight organic waste components such as alcohols, aldehydes, ketones, amides, and thiocarbamides to CO2 at low temperature (121 C), thereby reducing the total organic carbon (TOC) to below 500 ppb. The rate of reaction for the catalytic oxidation of aqueous organics to CO2 and water depends primarily upon the catalyst, temperature, and concentration of reactants. This paper describes a kinetic study conducted to determine the impact of each of these parameters upon the reaction rate. The results indicate that a classic kinetic model, the Langmuir-Hinshelwood rate equation for heterogeneous catalysis, can accurately represent the functional dependencies of this rate.

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

    Institute of Scientific and Technical Information of China (English)

    过玮; 刘利民; 林洪; 宋俊峰

    2002-01-01

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

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2004-09-28

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

  7. Visualizing a Catalyst at Work during the Ignition of the Catalytic Partial Oxidation of Methane

    DEFF Research Database (Denmark)

    Kimmerle, Bertram; Grunwaldt, Jan-Dierk; Baiker, Alfons;

    2009-01-01

    We present a spatiotemporal operando X-ray absorption study of a highly dynamic process, the ignition of the noble metal catalyzed partial oxidation of methane. Evolvement and propagation of the platinum component's structural changes are investigated with a high-speed X-ray camera, which in comb...... combination with temperature profiling by IR-thermography and catalytic activity measurements by online mass spectrometry gives insight into the first stages of the ignition of the reaction toward hydrogen and carbon monoxide....

  8. The catalytic oxidation of biomass to new materials focusing on starch, cellulose and lignin

    OpenAIRE

    Collinson, S. R.; Thielemans, W.

    2010-01-01

    Biomass is a renewable class of materials of growing interest amongst researchers aiming to achieve global sustainability. This review focuses on the homogeneous catalysis of the oxidation of biomass, in particular starch, cellulose and lignin. Often such catalytic reactions lead to depolymerisation of the material as happens in Nature with for example brown rot fungi. This depolymerisation can be desirable or not, and control in industrial applications is thus important to obtain the desired...

  9. Catalytic oxidation of cyanides in an aqueous phase over individual and manganese-modified cobalt oxide systems

    International Nuclear Information System (INIS)

    The possibility for purification of wastewaters containing free cyanides by applying of a new method based on cyanides catalytic oxidation with air to CO2 and N2 at low temperature and atmospheric pressure was investigated. On this purpose, individual and modified with manganese Co-oxide systems as active phase of environmental catalysts were synthesized. The applied method of synthesis favours the preparation of oxide catalytic systems with high active oxygen content (total-O* and surface-O*s) possessing high mobility, and the metal ions being in a high oxidation state and in an octahedral coordination-factors determining high activity in reactions of complete oxidation. The catalysts employed were characterized by powder X-ray diffraction, Infrared spectroscopy, and chemical analysis. The effect of pH of the medium and catalyst loading on the effectiveness of the cyanide oxidation process, expressed by the degree of conversion (α, %), by the rate constant (k, min-1), and COD was studied. The results obtained reveal that using catalysts investigated a high cyanide removal efficiency could be achieved even in strong alkaline medium. The higher activity of the manganese promoted catalytic sample could be explained on the basis of higher total active oxygen content and its higher mobility both depending on the conditions, under which the synthesis of catalyst is being carried out.

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

    DEFF Research Database (Denmark)

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

    1997-01-01

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

  11. Catalytic effects of trace ruthenium on oxidation of dimethyl yellow with bromate and its application

    Institute of Scientific and Technical Information of China (English)

    ZHOU Zhi-rong; WANG Qun; ZHANG Shu-yuan

    2008-01-01

    A spectrophotometric method for the determination of ruthenium(Ⅲ) is described, based on its catalytic effect on the oxidation reaction of dimethyl yellow (DMY) with potassium bromate in an acid solution medium and in the presence of an OP emulsifier (p-iso-octyl phenoxy polyethoxy ethanol) at 100 ℃. This reaction was followed spectrophotometrically by measuring the decrease in the absorbance at 530 nm of the catalytic reaction of DMY. The calibration curve for the recommended method was linear in the concentration range over 0.0-1.0 μg/Land the detection limit of the method for Ru(Ⅲ) was 0.01 μg/L. The method is highly sensitive, selective and very stable and has been successfully applied for the determination of trace amounts of ruthenium in some ores and metallurgy products with the relative standard deviations (RSD) over 1.6%-2.8% and a recovery over 98.7%-104.0%.

  12. Simultaneous removal of methylene blue and copper(II) ions by photoelectron catalytic oxidation using stannic oxide modified iron(III) oxide composite electrodes

    International Nuclear Information System (INIS)

    Highlights: • Photoelectron catalytic oxidation was used for methylene blue and Cu2+ removal. • SnO2/Fe2O3 was prepared and characterized for use as photoanodes and photocathodes. • Optimal reaction conditions were determined for methylene blue and Cu2+ removal. • Methylene blue removal followed the Langmuir–Freundlich–Hinshelwood kinetic model. • Cu2+ removal followed the first-order rate model. - Abstract: Stannic oxide modified Fe(III) oxide composite electrodes (SnO2/Fe2O3) were synthesized for simultaneously removing methylene blue (MB) and Cu(II) from wastewater using photoelectron catalytic oxidation (PEO). The SnO2/Fe2O3 electrodes were characterized using scanning electron microscopy (SEM), X-ray diffraction (XRD), and photoelectrochemical techniques. The removal of MB and Cu(II) by PEO using the SnO2/Fe2O3 composite electrodes was studied in terms of reaction time, electric current density, and pH of the electrolyte. The kinetics of the reactions were investigated using batch assays. The optimal reaction time, pH, and electric current density of the PEO process were determined to be 30 min, 6.0, and 10 mA/cm2, respectively. The removal rates of MB from wastewater treated by PEO and electron catalytic oxidation process were 84.87% and 70.64%, respectively, while the recovery rates of Cu(II) were 91.75% and 96.78%, respectively. The results suggest that PEO is an effective method for the simultaneous removal of MB and Cu(II) from wastewater, and the PEO process exhibits a much higher removal rate for MB and Cu(II) compared to the electron catalytic oxidation process. Furthermore, the removal of MB was found to follow the Langmuir–Freundlich–Hinshelwood kinetic model, whereas the removal of Cu(II) fitted well to the first-order reaction model

  13. Application of Catalytic Wet Air Oxidation to Treatment of Landfill Leachate on Co/Bi Catalyst

    Institute of Scientific and Technical Information of China (English)

    LI Hai-sheng; LIU Liang; ZHANG Rong; DONG De-ming; LIU Hong-liang; LI Yu

    2004-01-01

    Catalytic wet air oxidation(CWAO) was employed to reduce the organic compounds in landfill leachate and the effects of temperature, oxygen pressure, catalyst dosage, and concentration of the organic compounds on the TOC and CODCr removal rates were studied. The degradation kinetics of landfill leachate was also investigated and an exponential experiential model consisting of four influential factors was established to describe the reduction of the organic compounds in the landfill leachate. Meanwhile, the GC-MS technique was used to detect the components of the organic intermediates for the inference of the decomposition mechanisms of the organic compounds in landfill leachate. The results reveal that the reaction temperature and the catalyst dosage are the most important factors affecting the degradation reaction of the organic compounds and that the principal intermediates confirmed by GC-MS are organic acids at a percentage of more than 88% with no aldehydes or alcohols detected. The decomposition mechanisms of the organic compounds in landfill leachate were inferred based on the GC-MS information as follows: the activated gas phase O2 captured the hydrogen of the organic pollutants to produce free radicals, which then initiated the catalytic reaction. So most of the organic compounds were oxidized into CO2 and H2O ultimately. In general, catalytic wet air oxidation over catalyst Co3O4/Bi2O3 was a very promising technique for the treatment of landfill leachate.

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

    Institute of Scientific and Technical Information of China (English)

    Masoud Hasany; Mohammad Malakootikhah; Vahid Rahmanian; Soheila Yaghmaei

    2015-01-01

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

  15. Catalytic wet oxidation of thiocyanate with homogeneous copper(II) sulphate catalyst

    International Nuclear Information System (INIS)

    The wet oxidation of thiocyanate has been investigated in a semi-batch reactor at temperatures between 423 and 473 K and pressures between 6.1 x 103 and 1.0 x 104 kPa in the presence of copper(II) sulphate as catalyst. The effects of copper concentration, initial thiocyanate concentration, pressure and temperature on the reaction rate were analyzed and the main products of reaction were identified. A kinetic model for the Cu-catalyzed reaction is here proposed, including temperature, oxygen concentration, and the reduction of Cu2+ to Cu+ that gives an accurate prediction of the oxidation process under the assayed conditions. A mechanistic model based on the formation of a transition complex between a copper cation and two thiocyanate anions has been proposed for the catalytic wet oxidation.

  16. Catalytic performance of heteroatom-modified carbon nanotubes in advanced oxidation processes

    Institute of Scientific and Technical Information of China (English)

    João Restivo; Raquel P. Rocha; Adrián M. T. Silva; José J. M. Órfão; Manuel F. R. Pereira; José L. Figueiredo

    2014-01-01

    Multi-walled carbon nanotubes (CNTs) were submitted to chemical and thermal treatments in or-der to incorporate different heteroatoms on the surface. O-, S-and N-containing groups were suc-cessfully introduced onto the CNTs without significant changes of the textural properties. The cata-lytic activity of these heteroatom-modified CNTs was studied in two liquid phase oxidation pro-cesses:catalytic ozonation and catalytic wet air oxidation (CWAO), using oxalic acid and phenol as model compounds. In both cases, the presence of strongly acidic O-containing groups was found to decrease the catalytic activity of the CNTs. On the other hand, the introduction of S species (mainly sulfonic acids) enhanced the removal rate of the model compounds, particularly in the CWAO of phenol. Additional experiments were performed with a radical scavenger and sodium persulfate, in order to clarify the reaction mechanism. Nitrogen functionalities improve the catalytic performance of the original CNTs, regardless of the process or of the pollutant.

  17. Oxidative catalytic evolution of redox- and spin-states of a Fe-phthalocyanine studied by EPR

    Science.gov (United States)

    Bletsa, Eleni; Solakidou, Maria; Louloudi, Maria; Deligiannakis, Yiannis

    2016-04-01

    The catalytic-oxidative evolution of the redox/spin states of a Fe-phthalocyanine (Fe-Pc) catalyst was studied by electron paramagnetic resonance spectroscopy. Under oxidative catalytic conditions, Fe-Pc may evolve via multiple redox/spin conformations. Axial ligation of imidazole, O2 or t-Bu-OOH as oxidant, results in a complex multipath redox/spin landscape that was determined in detail herein. The high-spin conformations of Fe-Pc/imidazole evolve more slowly than the low-spin conformations. Catalytically active vs. inactive conformations were distinguished. A unified physicochemical catalytic reaction mechanism is discussed herein based on the distinct role of the various structural, spin and redox forms.

  18. How surface reparation prevents catalytic oxidation of carbon monoxide on atomic gold at defective magnesium oxide surfaces.

    Science.gov (United States)

    Töpfer, Kai; Tremblay, Jean Christophe

    2016-07-21

    In this contribution, we study using first principles the co-adsorption and catalytic behaviors of CO and O2 on a single gold atom deposited at defective magnesium oxide surfaces. Using cluster models and point charge embedding within a density functional theory framework, we simulate the CO oxidation reaction for Au1 on differently charged oxygen vacancies of MgO(001) to rationalize its experimentally observed lack of catalytic activity. Our results show that: (1) co-adsorption is weakly supported at F(0) and F(2+) defects but not at F(1+) sites, (2) electron redistribution from the F(0) vacancy via the Au1 cluster to the adsorbed molecular oxygen weakens the O2 bond, as required for a sustainable catalytic cycle, (3) a metastable carbonate intermediate can form on defects of the F(0) type, (4) only a small activation barrier exists for the highly favorable dissociation of CO2 from F(0), and (5) the moderate adsorption energy of the gold atom on the F(0) defect cannot prevent insertion of molecular oxygen inside the defect. Due to the lack of protection of the color centers, the surface becomes invariably repaired by the surrounding oxygen and the catalytic cycle is irreversibly broken in the first oxidation step. PMID:27345190

  19. In situ spectroscopy of catalytically active surfaces: FTIR and EXAFS studies of CO oxidation on Pd and Au nanoparticles

    International Nuclear Information System (INIS)

    This thesis was aiming at a comprehensive investigation of the reaction mechanism of CO oxidation, applying in situ Fourier Transform Infrared (FTIR) Spectroscopy and X- Ray Absorption Spectroscopy (XAS) under reaction conditions to different industrial-grade noble metal catalysts. For alumina supported palladium nanoparticles (∼2 and 5 nm) variable oxidative pre-treatments were utilized to identify and characterize palladium (sub)oxide species in different oxidation states. In situ EXAFS and in situ FTIR spectroscopy clearly demonstrated that such substoichiometric palladiumoxides PdOx (x<1) were also present during the CO oxidation reaction. Although they may contribute to activity, the highest catalytic activity was assigned to metallic palladium. The relatively high activity of the substoichiometric palladiumoxides (as compared to fully oxidized palladium(II)oxide) was attributed to their reducibility under technically relevant conditions by CO. The study of CO oxidation on Pd/Al2O3 indicated a coexistence of metallic Pd and PdOx under reaction conditions, with metallic palladium being essential for the activation of CO and molecular O2. Under specific reaction conditions this resulted in oscillatory behavior. The mechanism of CO oxidation on titania supported gold nanoparticles (∼4 nm) was also investigated. In situ FTIR spectroscopy identified metallic gold as CO adsorption site, whereas the oxygen adsorption site was located on the titania support. Adsorption experiments with isotopically labelled 13C18O demonstrated the involvement of hydroxyl groups of the titania support in the catalytic reaction. This explained the increase in catalytic activity upon addition of small amounts of water: water dissociates on titania producing an increased number of terminal OH groups on the catalyst surface. The results suggest a 'phase boundary-mechanism' of CO oxidation on Au/TiO2, with the reaction taking place at the oxide/metal interface. (author)

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

    OpenAIRE

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

    1993-01-01

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

  1. The chemical origin and catalytic activity of coinage metals: from oxidation to dehydrogenation.

    Science.gov (United States)

    Syu, Cih-Ying; Yang, Hao-Wen; Hsu, Fu-Hsing; Wang, Jeng-Han

    2014-04-28

    The high oxidation activity of coinage metals (Cu, Ag and Au) has been widely applied in various important reactions, such as oxidation of carbon monoxide, alkenes or alcohols. The catalytic behavior of those inert metals has mostly been attributable to their size effect, the physical effect. In the present study, the chemical effects on their high oxidation activity have been investigated. We mechanistically examine the direct and oxidative dehydrogenation (partial oxidation) reactions of ethanol to acetaldehyde on a series of transition metals (groups 9, 10 and 11) with identical physical characteristics and varied chemical origins using density functional theory (DFT) calculations and electronic structure analyses at the GGA-PW91 level. The energetic results show that coinage metals have much lower activation energies and higher exothermicities for the oxidative dehydrogenation steps although they have higher energy for the direct dehydrogenation reaction. In the electronic structure analyses, coinage metals with saturated d bands can efficiently donate electrons to O* and OH*, or other electronegative adspecies, and better promote their p bands to higher energy levels. The negatively charged O* and OH* with high-lying p bands are responsible for lowering the energies in oxidative steps. The mechanistic understanding well explains the better oxidation activity of coinage metals and provides valuable information on their utilization in other useful applications, for example, the dehydrogenation process. PMID:24626959

  2. Catalytic Partial Oxidation of Biomass/Oil Dispersion

    Czech Academy of Sciences Publication Activity Database

    Hanika, Jiří; Lederer, J.; Nečesaný, F.; Poslední, W.; Tukač, V.; Veselý, Václav

    Praha: Orgit, 2013 - (Kalenda, P.; Lubojacký, J.), 9-12 ISBN 978-80-86238-55-5. [International Conference on Chemical Technology (ICCT 2013) /1./. Mikulov (CZ), 08.04.2013-10.04.2013] R&D Projects: GA TA ČR TE01020080; GA MPO 2A-2TP1/024 Institutional support: RVO:67985858 Keywords : hydrocarbon oil * biomass * catalytic partial oxidation Subject RIV: CI - Industrial Chemistry, Chemical Engineering

  3. Catalytic Partial Oxidation of Biomass/Oil Mixture

    OpenAIRE

    Veselý, V; Hanika, J. (Jiří); Tukač, V.; LEDERER, J.; Kovač, D.

    2013-01-01

    Investigation was focussed to application of waste POX (partial oxidation), e.g., meal rape in form of suspension in high boiling hydrocarbons from crude oil distillation. There is an opportunity for utilization of biomass waste resulted from fuels bio-components production. A decrease of oxygen and water steam demand in feed for POX process was observed in this variant. Catalytic effect of iron nanoparticles or nickel nitrate as catalysts in improvement of the pilot plant biomass/oil partial...

  4. Catalytic activity of CuOn-La2O3/γ-Al2O3 for microwave assisted ClO2 catalytic oxidation of phenol wastewater

    International Nuclear Information System (INIS)

    In order to develop a catalyst with high activity and stability for microwave assisted ClO2 catalytic oxidation, we prepared CuOn-La2O3/γ-Al2O3 by impregnation-deposition method, and determined its properties using BET, XRF, XPS and chemical analysis techniques. The test results show that, better thermal ability of γ-Al2O3 and high loading of Cu in the catalyst can be achieved by adding La2O3. The microwave assisted ClO2 catalytic oxidation process with CuOn-La2O3/γ-Al2O3 used as catalyst was also investigated, and the results show that the catalyst has an excellent catalytic activity in treating synthetic wastewater containing 100 mg/L phenol, and 91.66% of phenol and 50.35% of total organic carbon (TOC) can be removed under the optimum process conditions. Compared with no catalyst process, CuOn-La2O3/γ-Al2O3 can effectively degrade contaminants in short reaction time and with low oxidant dosage, extensive pH range. The comparison of phenol removal efficiency in the different process indicates that microwave irradiation and catalyst work together to oxidize phenol effectively. It can therefore be concluded from results and discussion that CuOn-La2O3/γ-Al2O3 is a suitable catalyst in microwave assisted ClO2 catalytic oxidation process

  5. Catalytic oxidation of pulping effluent by activated carbon-supported heterogeneous catalysts.

    Science.gov (United States)

    Yadav, Bholu Ram; Garg, Anurag

    2016-01-01

    The present study deals with the non-catalytic and catalytic wet oxidation (CWO) for the removal of persistent organic compounds from the pulping effluent. Two activated carbon-supported heterogeneous catalysts (Cu/Ce/AC and Cu/Mn/AC) were used for CWO after characterization by the following techniques: temperature-programmed reduction, Fourier transform infrared spectroscopy and thermo-gravimetric analysis. The oxidation reaction was performed in a batch high-pressure reactor (capacity = 0.7  L) at moderate oxidation conditions (temperature = 190°C and oxygen pressure = 0.9 MPa). With Cu/Ce/AC catalyst, the maximum chemical oxygen demand (COD), total organic carbon (TOC) and lignin removals of 79%, 77% and 88% were achieved compared to only 50% removal during the non-catalytic process. The 5-day biochemical oxygen demand (BOD5) to COD ratio (a measure for biodegradability) of the pulping effluent was improved to 0.52 from an initial value of 0.16. The mass balance calculations for solid recovered after CWO reaction showed 8% and 10% deduction in catalyst mass primarily attributed to the loss of carbon and metal leaching. After the CWO process, carbon deposition was also observed on the recovered catalyst which was responsible for around 3-4% TOC reduction. PMID:26508075

  6. Magnetic bimetallic nanoparticles supported reduced graphene oxide nanocomposite: Fabrication, characterization and catalytic capability

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Lei; Wu, Tao; Xu, Xiaoyang; Xia, Fengling; Na, Heya [School of Science, Tianjin University, Tianjin 300072 (China); Liu, Yu, E-mail: liuyuls@163.com [School of Science, Tianjin University, Tianjin 300072 (China); Qiu, Haixia [School of Science, Tianjin University, Tianjin 300072 (China); Wang, Wei [School of Chemical Engineering, Tianjin University, Tianjin 300072 (China); Gao, Jianping, E-mail: jianpinggao2012@126.com [School of Science, Tianjin University, Tianjin 300072 (China)

    2015-04-15

    Highlights: • Ni and Ag nanoparticles loaded on RGO (Ni–Ag@RGO) were fabricated in a one-pot reaction. • The Ni–Ag@RGO were excellent catalysts for the reduction of 4-nitrophenol. • The Ni–Ag@RGO showed superior catalytic activity for photodegradation of methyl orange. • The Ni–Ag@RGO exhibit good reusability in a magnetic field. - Abstract: A facile method for preparing Ni–Ag bimetallic nanoparticles supported on reduced graphene oxide (Ni–Ag@RGO hybrid) has been established. Hydrazine hydrate was used as the reducing agent to reduce the graphene oxide, Ni{sup 2+} and Ag{sup +} to form Ni–Ag@RGO hybrid. The prepared hybrid was further characterized by X-ray diffraction, thermogravimetric analysis, X-ray photoelectron spectroscopy, and transmission electron microscopy. Interestingly, the prepared material shown good magnetic properties, which were determined by vibrating sample magnetometer. In addition, the Ni–Ag@RGO hybrid exhibited excellent catalytic activity for the reduction of 4-nitrophenol and the photodegradation of methyl orange. The catalytic process was monitored by determining the change in the concentration of the reactants with time using ultraviolet–visible absorption spectroscopy. After completion of the reaction, the catalyst can be separated from the reaction system simply under a magnet field and shows good recyclability.

  7. Oxidation-reduction reactions of metal ions.

    OpenAIRE

    Carter, D E

    1995-01-01

    Several metal or metalloid ions exist in multiple oxidation states and can undergo electron transfer reactions that are important in biological and environmental systems. There are endogenous metal ions such as iron, copper, and cobalt that participate in oxidation-reduction reactions with species of oxygen like molecular dioxygen, superoxide, and hydrogen peroxide. These reactions may be modulated by endogenous reducing agents such as glutathione, ascorbate, and tocopherol. The reactions can...

  8. Influence of Rare Earth Doping on the Structural and Catalytic Properties of Nanostructured Tin Oxide

    Directory of Open Access Journals (Sweden)

    Maciel Adeilton

    2008-01-01

    Full Text Available AbstractNanoparticles of tin oxide, doped with Ce and Y, were prepared using the polymeric precursor method. The structural variations of the tin oxide nanoparticles were characterized by means of nitrogen physisorption, carbon dioxide chemisorption, X-ray diffraction, and X-ray photoelectron spectroscopy. The synthesized samples, undoped and doped with the rare earths, were used to promote the ethanol steam reforming reaction. The SnO2-based nanoparticles were shown to be active catalysts for the ethanol steam reforming. The surface properties, such as surface area, basicity/base strength distribution, and catalytic activity/selectivity, were influenced by the rare earth doping of SnO2and also by the annealing temperatures. Doping led to chemical and micro-structural variations at the surface of the SnO2particles. Changes in the catalytic properties of the samples, such as selectivity toward ethylene, may be ascribed to different dopings and annealing temperatures.

  9. Electrochemical study on the cationic promotion of the catalytic SO2 oxidation in pyrosulfate melts

    DEFF Research Database (Denmark)

    Petrushina, Irina; Bjerrum, Niels; Cappeln, Frederik Vilhelm

    1998-01-01

    in the catalytic SO, oxidation most likely is the oxidation of V(IV) to V(V) and the Na+ and Cs+ promoting effect is based on the acceleration of this stage. It has also been proposed that voltammetric measurements can be used for fast optimization of the composition of the vanadium catalyst (which...... catalytic oxidation of SO2 in the V2O5-M2S2O7 system and the effect of these alkali cations on the electrochemical behavior of V2O5 in the alkali pyrosulfate melts It has been shown that Na+ ions had a promoting effect on the V(V) reversible arrow V(IV) electrochemical reaction. Sodium ions accelerate both...... the V(V) reduction and the V(IV) oxidation, the effect being more pronounced in the case of the V(IV) oxidation. Sodium ions also had a significant (almost 0.2 V) depolarization effect on the V(IV) --> V(V) oxidation. The peak current of the V(IV) --> V(V) oxidation waves vs. Na2S2O7 concentration...

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

    Science.gov (United States)

    Collins, Gillian; Holmes, Justin D

    2016-07-01

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

  11. Growth states of catalytic reaction networks exhibiting energy metabolism

    Science.gov (United States)

    Kondo, Yohei; Kaneko, Kunihiko

    2011-07-01

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

  12. Supercritical carbon dioxide as an innovative reaction medium for selective oxidation

    Energy Technology Data Exchange (ETDEWEB)

    Loeker, F.; Leitner, W. [Max-Planck-Institut fuer Kohlenforschung, Muelheim an der Ruhr (Germany)

    1998-12-31

    Although the catalytic efficiency of all catalytic oxidation processes studied in scCO{sub 2} up to now is far from being satisfactory, the principle possibility to carry out such reactions in this medium is clearly evident. Future research in our group will be directed towards the development of homogeneous and heterogeneous catalysts that are adopted to the special requirements of both the oxidation process and the supercritical reaction medium. Preliminary results from these studies regarding the epoxidation of olefins with molecular oxygen as oxidant will be presented on the conference poster. (orig.)

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

    Science.gov (United States)

    Prütz, W A

    1998-09-15

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

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

    Science.gov (United States)

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

    2011-01-01

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

  15. A green surfactant-assisted synthesis of hierarchical TS-1 zeolites with excellent catalytic properties for oxidative desulfurization.

    Science.gov (United States)

    Du, Shuting; Li, Fen; Sun, Qiming; Wang, Ning; Jia, Mingjun; Yu, Jihong

    2016-02-25

    Hierarchical TS-1 zeolites with uniform intracrystalline mesopores have been successfully synthesized through the hydrothermal method by using the green and cheap surfactant Triton X-100 as the mesoporous template. The resultant materials exhibit remarkably enhanced catalytic activity in oxidative desulfurization reactions compared to the conventional TS-1 zeolite. PMID:26881277

  16. Catalytic oxidation of volatile organic compounds (VOCs) - A review

    Science.gov (United States)

    Kamal, Muhammad Shahzad; Razzak, Shaikh A.; Hossain, Mohammad M.

    2016-09-01

    Emission of volatile organic compounds (VOCs) is one of the major contributors to air pollution. The main sources of VOCs are petroleum refineries, fuel combustions, chemical industries, decomposition in the biosphere and biomass, pharmaceutical plants, automobile industries, textile manufacturers, solvents processes, cleaning products, printing presses, insulating materials, office supplies, printers etc. The most common VOCs are halogenated compounds, aldehydes, alcohols, ketones, aromatic compounds, and ethers. High concentrations of these VOCs can cause irritations, nausea, dizziness, and headaches. Some VOCs are also carcinogenic for both humans and animals. Therefore, it is crucial to minimize the emission of VOCs. Among the available technologies, the catalytic oxidation of VOCs is the most popular because of its versatility of handling a range of organic emissions under mild operating conditions. Due to that fact, there are numerous research initiatives focused on developing advanced technologies for the catalytic destruction of VOCs. This review discusses recent developments in catalytic systems for the destruction of VOCs. Review also describes various VOCs and their sources of emission, mechanisms of catalytic destruction, the causes of catalyst deactivation, and catalyst regeneration methods.

  17. Synthesis of propylene carbonate from urea and propylene glycol over zinc oxide: A homogeneous reaction

    Directory of Open Access Journals (Sweden)

    Dengfeng Wang

    2014-11-01

    Full Text Available In this work, several metal oxides and zinc salts were used to catalyze propylene carbonate (PC synthesis from urea and propylene glycol (PG. According to the results of catalytic test and characterization, the catalytic pattern of ZnO was different from that of other metal oxides such as CaO, MgO and La2O3, but similar to that of zinc salts. In fact, the leaching of Zn species took place during reaction for ZnO. And ZnO was found to be the precursor of homogenous catalyst for reaction of urea and PG. Thus, the relationship between the amount of dissolved zinc species and the catalytic performance of employed ZnO was revealed. In addition, a possible reaction mechanism over ZnO was discussed based on the catalytic runs and the characterization of XRD, FTIR, and element analysis.

  18. Activated carbon and tungsten oxide supported on activated carbon catalysts for toluene catalytic combustion.

    Science.gov (United States)

    Alvarez-Merino, M A; Ribeiro, M F; Silva, J M; Carrasco-Marín, F; Maldonado-Hódar, F J

    2004-09-01

    We have used activated carbon (AC) prepared from almond shells as a support for tungsten oxide to develop a series of WOx/AC catalysts for the catalytic combustion of toluene. We conducted the reaction between 300 and 350 degrees C, using a flow of 500 ppm of toluene in air and space velocity (GHSV) in the range 4000-7000 h(-1). Results show that AC used as a support is an appropriate material for removing toluene from dilute streams. By decreasing the GHSV and increasing the reaction temperature AC becomes a specific catalyst for the total toluene oxidation (SCO2 = 100%), but in less favorable conditions CO appears as reaction product and toluene-derivative compounds are retained inside the pores. WOx/AC catalysts are more selective to CO2 than AC due to the strong acidity of this oxide; this behavior improves with increased metal loading and reaction temperature and contact time. The catalytic performance depends on the nonstoichiometric tungsten oxide obtained during the pretreatment. In comparison with other supports the WOx/AC catalysts present, at low reaction temperatures, higher activity and selectivity than WO, supported on SiO2, TiO2, Al2O3, or Y zeolite. This is due to the hydrophobic character of the AC surface which prevents the adsorption of water produced from toluene combustion thus avoiding the deactivation of the active centers. However, the use of WOx/AC system is always restricted by its gasification temperature (around 400 degrees C), which limits the ability to increase the conversion values by increasing reaction temperatures. PMID:15461177

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

    International Nuclear Information System (INIS)

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

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

    OpenAIRE

    Chhabra, Vibhuti

    2014-01-01

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

  1. Catalytic oxidative desulfurization of liquid hydrocarbon fuels using air

    Science.gov (United States)

    Sundararaman, Ramanathan

    Conventional approaches to oxidative desulfurization of liquid hydrocarbons involve use of high-purity, expensive water soluble peroxide for oxidation of sulfur compounds followed by post-treatment for removal of oxidized sulfones by extraction. Both are associated with higher cost due to handling, storage of oxidants and yield loss with extraction and water separation, making the whole process more expensive. This thesis explores an oxidative desulfurization process using air as an oxidant followed by catalytic decomposition of sulfones thereby eliminating the aforementioned issues. Oxidation of sulfur compounds was realized by a two step process in which peroxides were first generated in-situ by catalytic air oxidation, followed by catalytic oxidation of S compounds using the peroxides generated in-situ completing the two step approach. By this technique it was feasible to oxidize over 90% of sulfur compounds present in real jet (520 ppmw S) and diesel (41 ppmw S) fuels. Screening of bulk and supported CuO based catalysts for peroxide generation using model aromatic compound representing diesel fuel showed that bulk CuO catalyst was more effective in producing peroxides with high yield and selectivity. Testing of three real diesel fuels obtained from different sources for air oxidation over bulk CuO catalyst showed different level of effectiveness for generating peroxides in-situ which was consistent with air oxidation of representative model aromatic compounds. Peroxides generated in-situ was then used as an oxidant to oxidize sulfur compounds present in the fuel over MoO3/SiO2 catalyst. 81% selectivity of peroxides for oxidation of sulfur compounds was observed on MoO3/SiO2 catalyst at 40 °C and under similar conditions MoO3/Al2O3 gave only 41% selectivity. This difference in selectivity might be related to the difference in the nature of active sites of MoO3 on SiO2 and Al2O 3 supports as suggested by H2-TPR and XRD analyses. Testing of supported and bulk Mg

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

    Institute of Scientific and Technical Information of China (English)

    Gao Yongcan; Zhang Jiushun; Xie Chaogang; Long Jun

    2002-01-01

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

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

    Science.gov (United States)

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

    2009-08-01

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

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

    Science.gov (United States)

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

    2011-01-01

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

  5. Degradation of paracetamol by catalytic wet air oxidation and sequential adsorption – Catalytic wet air oxidation on activated carbons

    International Nuclear Information System (INIS)

    Highlights: ► Three activated carbons (AC) compared as adsorbents and oxidation catalysts. ► Similar evolution for catalytic and adsorptive properties of AC over reuses. ► Acidic and mesoporous AC to be preferred, despite lower initial efficiency. ► Oxidative degradation of paracetamol improves biodegradability. ► Convenient hybrid adsorption–regenerative oxidation process for continuous treatment. - Abstract: The concern about the fate of pharmaceutical products has raised owing to the increasing contamination of rivers, lakes and groundwater. The aim of this paper is to evaluate two different processes for paracetamol removal. The catalytic wet air oxidation (CWAO) of paracetamol on activated carbon was investigated both as a water treatment technique using an autoclave reactor and as a regenerative treatment of the carbon after adsorption in a sequential fixed bed process. Three activated carbons (ACs) from different source materials were used as catalysts: two microporous basic ACs (S23 and C1) and a meso- and micro-porous acidic one (L27). During the first CWAO experiment the adsorption capacity and catalytic performance of fresh S23 and C1 were higher than those of fresh L27 despite its higher surface area. This situation changed after AC reuse, as finally L27 gave the best results after five CWAO cycles. Respirometry tests with activated sludge revealed that in the studied conditions the use of CWAO enhanced the aerobic biodegradability of the effluent. In the ADOX process L27 also showed better oxidation performances and regeneration efficiency. This different ageing was examined through AC physico-chemical properties.

  6. Degradation of paracetamol by catalytic wet air oxidation and sequential adsorption - Catalytic wet air oxidation on activated carbons

    Energy Technology Data Exchange (ETDEWEB)

    Quesada-Penate, I. [Universite de Toulouse, INPT, UPS, Laboratoire de Genie Chimique, 4, Allee Emile Monso, F-31432 Toulouse (France); CNRS, Laboratoire de Genie Chimique, F-31432 Toulouse (France); Julcour-Lebigue, C., E-mail: carine.julcour@ensiacet.fr [Universite de Toulouse, INPT, UPS, Laboratoire de Genie Chimique, 4, Allee Emile Monso, F-31432 Toulouse (France); CNRS, Laboratoire de Genie Chimique, F-31432 Toulouse (France); Jauregui-Haza, U.J. [Instituto Superior de Tecnologias y Ciencias Aplicadas, Ave. Salvador Allende y Luaces, Habana (Cuba); Wilhelm, A.M.; Delmas, H. [Universite de Toulouse, INPT, UPS, Laboratoire de Genie Chimique, 4, Allee Emile Monso, F-31432 Toulouse (France); CNRS, Laboratoire de Genie Chimique, F-31432 Toulouse (France)

    2012-06-30

    Highlights: Black-Right-Pointing-Pointer Three activated carbons (AC) compared as adsorbents and oxidation catalysts. Black-Right-Pointing-Pointer Similar evolution for catalytic and adsorptive properties of AC over reuses. Black-Right-Pointing-Pointer Acidic and mesoporous AC to be preferred, despite lower initial efficiency. Black-Right-Pointing-Pointer Oxidative degradation of paracetamol improves biodegradability. Black-Right-Pointing-Pointer Convenient hybrid adsorption-regenerative oxidation process for continuous treatment. - Abstract: The concern about the fate of pharmaceutical products has raised owing to the increasing contamination of rivers, lakes and groundwater. The aim of this paper is to evaluate two different processes for paracetamol removal. The catalytic wet air oxidation (CWAO) of paracetamol on activated carbon was investigated both as a water treatment technique using an autoclave reactor and as a regenerative treatment of the carbon after adsorption in a sequential fixed bed process. Three activated carbons (ACs) from different source materials were used as catalysts: two microporous basic ACs (S23 and C1) and a meso- and micro-porous acidic one (L27). During the first CWAO experiment the adsorption capacity and catalytic performance of fresh S23 and C1 were higher than those of fresh L27 despite its higher surface area. This situation changed after AC reuse, as finally L27 gave the best results after five CWAO cycles. Respirometry tests with activated sludge revealed that in the studied conditions the use of CWAO enhanced the aerobic biodegradability of the effluent. In the ADOX process L27 also showed better oxidation performances and regeneration efficiency. This different ageing was examined through AC physico-chemical properties.

  7. Development of the Monolith Froth Reactor for Catalytic Wet Oxidation of CELSS Model Wastes

    Science.gov (United States)

    Abraham, Martin; Fisher, John W.

    1995-01-01

    The aqueous phase oxidation of acetic acid, used as a model compound for the treatment of CELSS (Controlled Ecological Life Support System) waste, was carried out in the monolith froth reactor which utilizes two-phase flow in the monolith channels. The catalytic oxidation of acetic acid was carried out over a Pt/Al2O3 catalyst, prepared at The University of Tulsa, at temperatures and pressures below the critical point of water. The effect of externally controllable parameters (temperature, liquid flow rate, distributor plate orifice size, pitch, and catalyst distance from the distributor plate) on the rate of acetic acid oxidation was investigated. Results indicate reaction rate increased with increasing temperature and exhibited a maximum with respect to liquid flow rate. The apparent activation energy calculated from reaction rate data was 99.7 kJ/mol. This value is similar to values reported for the oxidation of acetic acid in other systems and is comparable to intrinsic values calculated for oxidation reactions. The kinetic data were modeled using simple power law kinetics. The effect of "froth" feed system characteristics was also investigated. Results indicate that the reaction rate exhibits a maximum with respect to distributor plate orifice size, pitch, and catalyst distance from the distributor plate. Fundamental results obtained were used to extrapolate where the complete removal of acetic acid would be obtained and for the design and operation of a full scale CELSS treatment system.

  8. Wet Air Oxidation and Catalytic Wet Air Oxidation for Refinery Spent Caustics Degradation

    International Nuclear Information System (INIS)

    The work focuses on evaluating wet air oxidation and catalytic wet air oxidation technique to degrade refinery spent caustics (original COD is 250,781 mg/L) in a milder operation conditions (150-200 degree C, 0.2-2.5MPa). The results show that: in non-catalyst WAO, the highest COD degradation conversion could reach about 75% when 200 degree C, 2MPa oxygen and 300rpm were used. At every temperature, the reaction procedures follow pseudo-first order equations and the activation energy is 45.5 kJ/mol. The reactivity of three main contaminants in wastewater is on the order of sulphide > petroleum > volatile phenol. The COD degradation conversion could improve to about 95% when composite catalyst MnOx-CeO/sub x//sub x/ gamma-Al/sub 2/O/sub 3/ (W/sub Mn//W gamma-/sub Al/sub 2/O/sub 3/ =0.5/ and WCe/W MnOx Al/sub 2/O/sub 3/=0.4) was used. The pseudo-first order equations also could be applied for catalyst system and its activation energy decreases to 27.2 kJ/mol. The catalyst could improve the degradation efficiency of petroleum and volatile phenol. Their conversions could increase to 85% and 74% respectively after catalyst used. (author)

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

    Directory of Open Access Journals (Sweden)

    ALIREZA HASANINEJAD

    2010-03-01

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

  10. Heterogeneous catalytic oxidation of As(III) on nonferrous metal oxides in the presence of H2O2.

    Science.gov (United States)

    Kim, Dong-hyo; Bokare, Alok D; Koo, Min suk; Choi, Wonyong

    2015-03-17

    The oxidation of As(III) (arsenite) to As(V) (arsenate), a critical pretreatment process for total arsenic removal, is easily achieved using chemical oxidation methods. Hydrogen peroxide (H2O2) is widely used as an environmentally benign oxidant but its practical use for the arsenite oxidation is limited by the strong pH dependence and slow oxidation kinetics. This study demonstrated that H2O2-induced oxidation of As(III) can be markedly enhanced in the presence of nonferrous metal oxides (e.g., WO3, TiO2, ZrO2) as a heterogeneous catalyst working over a wide pH range in ambient reaction conditions. In particular, TiO2 is an ideal catalyst because it is not only active and stable but also easily available and inexpensive. Although the photocatalytic oxidation of As(III) on TiO2 was intensively studied, the thermal catalytic activities of TiO2 and other nonferrous metal oxides for the arsenic oxidation have been little investigated. The heterogeneous oxidation rate increased with increasing the TiO2 surface area and [H2O2] and weakly depended on pH whereas the homogeneous oxidation by H2O2 alone was favored only at alkaline condition. The oxidation rate in the TiO2/H2O2 system was not reduced at all in the absence of dioxygen. It was not retarded at all by OH radical scavengers but markedly inhibited by hydroperoxyl radical scavengers. It is proposed that the surface complexation of H2O2 on TiO2 induces the generation of the surface hydroperoxyl radical through an inner-sphere electron transfer, which subsequently reacts with As(III). The catalytic activity of TiO2 was maintained without showing any sign of deactivation. The heterogeneous catalytic oxidation is proposed as a viable method for the preoxidation treatment of As(III)-contaminated water under ambient conditions. PMID:25695481

  11. Structure and Catalytic Behavior of CuO-ZrO-CeO2 Mixed Oxides

    Institute of Scientific and Technical Information of China (English)

    王恩过; 陈诵英

    2002-01-01

    The effect of doping CuO on the structure and properties of zirconia-ceria mixed oxide was studied. The results show that addition of CuO decreases the reduction temperature of ceria, and stabilizes the cubic structure of mixed oxides, and enhances catalytic activity of CuO-ZrO-CeO2 mixed oxides for CO oxidation. Increasing ceria content in the mixed oxides can enhance the catalytic activity, but some impurities such as sulfate make catalytic activity falling. There is little effect of calcination temperature on catalytic activities, implying that these catalysts are effective with good thermal stability.

  12. Uranium oxidation: characterization of oxides formed by reaction with water

    International Nuclear Information System (INIS)

    Three different uranium oxide samples have been characterized with respect to the different preparation techniques. Results show that the water reaction with uranium metal occurs cyclically forming laminar layers of oxide which spall off due to the strain at the oxide/metal interface. Single laminae are released if liquid water is present due to the prizing penetration at the reaction zone. The rate of reaction of water with uranium is directly proportional to the amount of adsorbed water on the oxide product. Rapid transport is effected through the open hydrous oxide product. Dehydration of the hydrous oxide irreversibly forms a more inert oxide which cannot be rehydrated to the degree that prevails in the original hydrous product of uranium oxidation with water. 27 figures

  13. Highly n-Type Titanium Oxide as an Electronically Active Support for Platinum in the Catalytic Oxidation of Carbon Monoxide

    KAUST Repository

    Baker, L. Robert

    2011-08-18

    The role of the oxide-metal interface in determining the activity and selectivity of chemical reactions catalyzed by metal particles on an oxide support is an important topic in science and industry. A proposed mechanism for this strong metal-support interaction is electronic activation of surface adsorbates by charge carriers. Motivated by the goal of using electronic activation to drive nonthermal chemistry, we investigated the ability of the oxide support to mediate charge transfer. We report an approximately 2-fold increase in the turnover rate of catalytic carbon monoxide oxidation on platinum nanoparticles supported on stoichiometric titanium dioxide (TiO2) when the TiO2 is made highly n-type by fluorine (F) doping. However, for nonstoichiometric titanium oxide (TiOX<2) the effect of F on the turnover rate is negligible. Studies of the titanium oxide electronic structure show that the energy of free electrons in the oxide determines the rate of reaction. These results suggest that highly n-type TiO2 electronically activates adsorbed oxygen (O) by electron spillover to form an active O- intermediate. © 2011 American Chemical Society.

  14. Palladium-catalyzed oxidative carbonylation reactions.

    Science.gov (United States)

    Wu, Xiao-Feng; Neumann, Helfried; Beller, Matthias

    2013-02-01

    Palladium-catalyzed coupling reactions have become a powerful tool for advanced organic synthesis. This type of reaction is of significant value for the preparation of pharmaceuticals, agrochemicals, as well as advanced materials. Both, academic as well as industrial laboratories continuously investigate new applications of the different methodologies. Clearly, this area constitutes one of the major topics in homogeneous catalysis and organic synthesis. Among the different palladium-catalyzed coupling reactions, several carbonylations have been developed and widely used in organic syntheses and are even applied in the pharmaceutical industry on ton-scale. Furthermore, methodologies such as the carbonylative Suzuki and Sonogashira reactions allow for the preparation of interesting building blocks, which can be easily refined further on. Although carbonylative coupling reactions of aryl halides have been well established, palladium-catalyzed oxidative carbonylation reactions are also interesting. Compared with the reactions of aryl halides, oxidative carbonylation reactions offer an interesting pathway. The oxidative addition step could be potentially avoided in oxidative reactions, but only few reviews exist in this area. In this Minireview, we summarize the recent development in the oxidative carbonylation reactions. PMID:23307763

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

    Science.gov (United States)

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

    2001-01-01

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

  16. Photo catalytic Oxidation of Carbon Monoxide over NiO/SnO2 Nano composites under UV Irradiation

    International Nuclear Information System (INIS)

    The NiO/SnO2 nano composites have been prepared by the simple coprecipitation method and further characterized by the XRD, SEM, TEM, UV-Vis, and BET. X-ray diffraction (XRD) data analyses indicate the exclusive formation of nano sized particles with rutile-type phase (tetragonal SnO2) for Ni contents below 10 mol%. Only above 10 mol% Ni, the formation of a second NiO-related phase has been determined. The particle size is in the range from 12 to 6 nm. It decreases with increasing amounts of doping NiO. The morphology of NiO-doped SnO2 nanocrystalline powders is spherical, and the distribution of particle size is uniform, as seen from transmission electron microscopy (TEM). The photo catalytic oxidation of CO over NiO/SnO2 photo catalyst has been investigated under UV irradiation. Effects of NiO loading on SnO2, photo catalyst loading, and reaction time on photo catalytic oxidation of CO have been systematically studied. Compared with pure SnO2, the 33.3 mol% NiO/SnO2 composite exhibited approximately twenty fold enhancement of photo catalytic oxidation of CO. Our results provide a method for pollutants removal. Due to simple preparation, high photo catalytic oxidation of CO, and low cost, the NiO/SnO2 photo catalyst will find wide application in the coming future of photo catalytic oxidation of CO

  17. Surface-oxidized carbon black as a catalyst for the water oxidation and alcohol oxidation reactions.

    Science.gov (United States)

    Suryanto, Bryan H R; Zhao, Chuan

    2016-05-11

    Carbon black (CB) is popularly used as a catalyst support for metal/metal oxide nanoparticles due to its large surface area, excellent conductivity and stability. Herein, we show that surface oxidized CB itself, after acidic treatment and electrochemical oxidation, exhibits significant catalytic activity for the electrochemical oxidation of water and alcohols. PMID:27097802

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2010-01-01

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

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

    Science.gov (United States)

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

    2016-02-01

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

  20. Communication: Towards catalytic nitric oxide reduction via oligomerization on boron doped graphene

    Science.gov (United States)

    Cantatore, Valentina; Panas, Itai

    2016-04-01

    We use density functional theory to describe a novel way for metal free catalytic reduction of nitric oxide NO utilizing boron doped graphene. The present study is based on the observation that boron doped graphene and O—N=N—O- act as Lewis acid-base pair allowing the graphene surface to act as a catalyst. The process implies electron assisted N=N bond formation prior to N—O dissociation. Two N2 + O2 product channels, one of which favoring N2O formation, are envisaged as outcome of the catalytic process. Besides, we show also that the N2 + O2 formation pathways are contrasted by a side reaction that brings to N3O3- formation and decomposition into N2O + NO2-.

  1. Final Report, "Molecular Design of Hydrocarbon Oxidation Catalytic Processes"

    Energy Technology Data Exchange (ETDEWEB)

    Professor Francisco Zaera

    2007-08-09

    production of small amounts of ethylene and water, most likely via the concerted decomposition or disproportionation of the adsorbed molecular species. The bulk of the 2-iodoethanol decomposes at about 150 K via an initial carbon-iodine scission to form –O(H)CH2CH2– (~80%) and 2-hydroxyethyl (~20%) intermediates. Two competing reactions are involved with the subsequent conversion of the 2-hydroxyethyl species around 160 K, a reductive elimination with surface hydrogen to yield ethanol, and a β-H elimination to surface vinyl alcohol. The –O(H)CH2CH2–, on the other hand, dehydrogenates to a –OCH2CH2– oxametallacycle species about the same temperature. Both 2-hydroxyethyl and oxametallacycle species tautomerize to acetaldehyde, around 210 K and above 250 K, respectively, and some of that acetaldehyde desorbs while the rest decomposes to hydrogen and carbon monoxide. We contend that a better understanding of the surface chemistry of oxygen-containing surfaces can lead to better selectivities in catalysis. This is arguably the most important issue in the field of catalysis in the near future, and one that impacts several technologies of interest to DOE such as the manufacturing of speciality chemicals and the control and removal of pollutants. Additional work was performed on the characterization of the chemistry of methyl and methylene adsorbed species on oxygen-treated nickel surfaces. Complex chemistry was observed involving not only hydrogenation and dehydrogenation steps, but also C-C couplings and methylene insertions to produce heavier hydrocarbons, and oxygen insertion reactions that yield oxygenates. Finally, a dual titration technique employing xenon and a chemically sensitive probe was developed to identify minority catalytic sites on oxide surfaces. In the case of oxygen-treated Ni(110) single crystals, it was found that both hydrogen transfer with adsorbed water or ammonia and certain hydrocarbon hydrogenation reactions take place at the end of the

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

    Science.gov (United States)

    Danda, Adithi; Kumar, Kamal; Waldmann, Herbert

    2015-05-01

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

  3. Investigation of the Cu-Zr-Y oxides activity in the carbon black catalytic oxidation by differential thermal analysis and temperature programmed reduction

    International Nuclear Information System (INIS)

    Different copper/zirconium-yttrium catalysts have been tested in carbon black oxidation reaction. Supported mainly on differential thermal analysis and temperature programmed reduction, two different mechanisms have been proposed to explain the catalytic results. In the absence of copper, it has been shown that Zr3+ ions and associated anionic vacancies are responsible to the catalytic enhancement observed in the mixed oxides, oxygen species being activated on these sites. Among mixed zirconia-yttria solids, ZrO2-5 mol%Y2O3 is the most active catalyst. Copper impregnation on these oxides leads to the formation of different copper species. Small particles of CuO in low interaction with the support, induce a catalytic improvement due to the highest reducibility of these species. Moreover, in order to be more efficient, CuO species should have some interactions with the support, since impregnated samples are more active than the simple mechanical mixtures

  4. Synthesis of propylene carbonate from urea and propylene glycol over zinc oxide: A homogeneous reaction

    OpenAIRE

    Dengfeng Wang; Xuelan Zhang; Tingting Cheng; Jing Wu; Qijun Xue

    2014-01-01

    In this work, several metal oxides and zinc salts were used to catalyze propylene carbonate (PC) synthesis from urea and propylene glycol (PG). According to the results of catalytic test and characterization, the catalytic pattern of ZnO was different from that of other metal oxides such as CaO, MgO and La2O3, but similar to that of zinc salts. In fact, the leaching of Zn species took place during reaction for ZnO. And ZnO was found to be the precursor of homogenous catalyst for reaction of u...

  5. Reactions of oxidation of plutonium metal

    International Nuclear Information System (INIS)

    The investigation into preparation of the powdery plutonium oxides under the reaction of metal plutonium with moist (5 % H2O) air and moist (5 % H2O) argon was carried out. The kinetic dependences in the 250 - 400 Deg C range are demonstrated. The vicissitude of the oxidation is shown, the activation energy is calculated for every stage. The mechanism of the metal plutonium oxidation is proposed. The obtained plutonium oxides were shown to have a high reaction ability at 300 - 400 Deg C in the moist air and moist argon media, and to be feasible for the further chemical treatment - dissolving in nitric acid, fluorination and chlorination

  6. Acid Separation, Catalytic Oxidation and Coagulation for ATC Waste Liquid Treatment

    Institute of Scientific and Technical Information of China (English)

    DING Xiaoling; JIA Chunning

    2005-01-01

    It is difficult to treat 2-amino-thiazoline-4-carboxylic acid (ATC) waste liquid effectively at present for its characteristics of high chemical oxygen demand (COD), high salinity and low biodegradability. In order to solve this problem, this paper presents several kinds of physical-chemical treatment unit techniques, including acid separation, catalytic oxidation and coagulation. First of all, acid separation was adopted to precipitate relevant organics at isoelectric point. When the temperature and pH value of acid separation were controlled at about 5 ℃ and 2.2 respectively, the COD removal rate could reach 27.6%. Secondly, oxidation was used to break chemical constitution of refractory organics. The optimal reaction parameters of catalytic oxidation should be 20 ℃, pH adjusted to 5.0 and [Fe2+] 300 mg/L. Then with 5% H 2O 2 added and after one-hour reaction, the COD removal rate could achieve about 52%. Finally, coagulation was adopted to remove a portion of refractory organics, and 15% polymeric molysite flocculant was the best for the coagulation, and the COD removal rate could reach about 15%. Therefore, the proposed feasible process of physical-chemical pretreatment for ATC waste liquid could have about 70% COD removed in total.

  7. Oscillations, period doublings, and chaos in CO oxidation and catalytic mufflers.

    Science.gov (United States)

    Marek, Milos; Schejbal, Matyás; Kocí, Petr; Nevoral, Vladislav; Kubícek, Milan; Hadac, Otto; Schreiber, Igor

    2006-09-01

    Early experimental observations of chaotic behavior arising via the period-doubling route for the CO catalytic oxidation both on Pt(110) and Ptgamma-Al(2)O(3) porous catalyst were reported more than 15 years ago. Recently, a detailed kinetic reaction scheme including over 20 reaction steps was proposed for the catalytic CO oxidation, NO(x) reduction, and hydrocarbon oxidation taking place in a three-way catalyst (TWC) converter, the most common reactor for detoxification of automobile exhaust gases. This reactor is typically operated with periodic variation of inlet oxygen concentration. For an unforced lumped model, we report results of the stoichiometric network analysis of a CO reaction subnetwork determining feedback loops, which cause the oscillations within certain regions of parameters in bifurcation diagrams constructed by numerical continuation techniques. For a forced system, numerical simulations of the CO oxidation reveal the existence of a period-doubling route to chaos. The dependence of the rotation number on the amplitude and period of forcing shows a typical bifurcation structure of Arnold tongues ordered according to Farey sequences, and positive Lyapunov exponents for sufficiently large forcing amplitudes indicate the presence of chaotic dynamics. Multiple periodic and aperiodic time courses of outlet concentrations were also found in simulations using the lumped model with the full TWC kinetics. Numerical solutions of the distributed model in two geometric coordinates with the CO oxidation subnetwork consisting of several tens of nonlinear partial differential equations show oscillations of the outlet reactor concentrations and, in the presence of forcing, multiple periodic and aperiodic oscillations. Spatiotemporal concentration patterns illustrate the complexity of processes within the reactor. PMID:17014241

  8. Electro-catalytic effect of manganese oxide on oxygen reduction at teflonbonded carbon electrode

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    Oxygen reduction(OR)on Teflon-bonded carbon electrodes with manganese oxide as catalyst in 6 mol/L KOH solution was investigated using AC impedance spectroscopy combined with other techniques. For OR at this electrode, the Tafel slope is-0.084V/dec and the apparent exchange current density is (1.02-3.0)×10-7 A/cm2. In the presence of manganese oxide on carbon electrode,the couple Mn3+/Mn4+ reacts with the O2 adsorbed on carbon sites forming O2- radicals and acceletes the dismutation of O2-, which contributes to the catalytic effect of manganese oxide for OR reaction.

  9. Catalytic ozonation of sulfosalicylic acid over manganese oxide supported on mesoporous ceria.

    Science.gov (United States)

    Xing, Shengtao; Lu, Xiaoyang; Liu, Jia; Zhu, Lin; Ma, Zichuan; Wu, Yinsu

    2016-02-01

    Manganese oxide supported on mesoporous ceria was prepared and used as catalyst for catalytic ozonation of sulfosalicylic acid (SA). Characterization results indicated that the manganese oxide was mostly incorporated into the pores of ceria. The synthesized catalyst exhibited high activity and stability for the mineralization of SA in aqueous solution by ozone, and more than 95% of total organic carbon was removed in 30 min under various conditions. Mechanism studies indicated that SA was mainly degraded by ozone molecules, and hydroxyl radical reaction played an important role for the degradation of its ozonation products (small molecular organic acids). The manganese oxide in the pores of CeO2 improved the adsorption of small molecular organic acids and the generation of hydroxyl radicals from ozone decomposition, resulting in high TOC removal efficiency. PMID:26344143

  10. Laccase-Functionalized Graphene Oxide Assemblies as Efficient Nanobiocatalysts for Oxidation Reactions

    Science.gov (United States)

    Patila, Michaela; Kouloumpis, Antonios; Gournis, Dimitrios; Rudolf, Petra; Stamatis, Haralambos

    2016-01-01

    Multi-layer graphene oxide-enzyme nanoassemblies were prepared through the multi-point covalent immobilization of laccase from Trametes versicolor (TvL) on functionalized graphene oxide (fGO). The catalytic properties of the fGO-TvL nanoassemblies were found to depend on the number of the graphene oxide-enzyme layers present in the nanostructure. The fGO-TvL nanoassemblies exhibit an enhanced thermal stability at 60 °C, as demonstrated by a 4.7-fold higher activity as compared to the free enzyme. The multi-layer graphene oxide-enzyme nanoassemblies can efficiently catalyze the oxidation of anthracene, as well as the decolorization of an industrial dye, pinacyanol chloride. These materials retained almost completely their decolorization activity after five reaction cycles, proving their potential as efficient nano- biocatalysts for various applications. PMID:26927109

  11. Removal of formaldehyde over MnxCe1-xO2 catalysts: Thermal catalytic oxidation versus ozone catalytic oxidation

    Institute of Scientific and Technical Information of China (English)

    Jia Wei Li; Kuan Lun Pan; Sheng Jen Yu; Shaw Yi Yan; Moo Been Chang

    2014-01-01

    MnxCe1-xO2 (x:0.3-0.9) prepared by Pechini method was used as a catalyst for the thermal catalytic oxidation of formaldehyde (HCHO).At x =0.3 and 0.5,most of the manganese was incorporated in the fluorite structure of CeO2 to form a solid solution.The catalytic activity was best at x =0.5,at which the temperature of 100% removal rate is the lowest (270℃).The temperature for 100% removal of HCHO oxidation is reduced by approximately 40℃ by loading 5 wt.% CuOx into Mn0.5Ce0.5O2.With ozone catalytic oxidation,HCHO (61 ppm) in gas stream was completely oxidized by adding 506 ppm O3 over Mn0.5Ce0.5O2 catalyst with a GHSV (gas hourly space velocity) of 10,000 hr-1 at 25℃.The effect of the molar ratio of O3 to HCHO was also investigated.As O3/HCHO ratio was increased from 3 to 8,the removal efficiency of HCHO was increased from 83.3% to 100%.With O3/HCHO ratio of 8,the mineralization efficiency of HCHO to CO2 was 86.1%.At 25℃,the p-type oxide semiconductor (Mn0.5Ce0.5O2) exhibited an excellent ozone decomposition efficiency of 99.2%,which significantly exceeded that of n-type oxide semiconductors such as TiO2,which had a low ozone decomposition efficiency (9.81%).At a GHSV of 10,000 hr-1,[O3]/[HCHO] =3 and temperature of 25℃,a high HCHO removal efficiency (≥81.2%) was maintained throughout the durability test of 80 hr,indicating the long-term stability of the catalyst for HCHO removal.

  12. Catalytic and electrocatalytic oxidation of carbon monoxide on a Fe electrode in a solid electrolyte cell

    International Nuclear Information System (INIS)

    The catalytic oxidation of carbon monoxide on Fe catalyst was studied at 300-500C and atmospheric total pressure. The reaction was studied under both open- and closed-circuit operation in an yttria-stabilized zirconia solid electrolyte cell. The technique of Solid Electrolyte Potentiometry (SEP) was used to monitor the thermodynamic activity of oxygen adsorbed on the Fe electrode under open circuit. Kinetic and potentiometric measurements were combined in order to elucidate the reaction mechanism. The results are in agreement with a Langmuir-Hinselwood type of adsorption-reaction with two different adsorption sites for carbon monoxide and oxygen. Under closed circuit, the effect of electrochemical oxygen 'pumping' to the catalyst was examined. The operation of the cell was almost Faradaic as the rate enhancement factor (λ) values measured were close to unity

  13. Catalytic activity of non-stoichiometric mixed transition metal oxides of praseodymium with cobalt and nickel of Ln2 MO4 type

    International Nuclear Information System (INIS)

    Non- Stoichiometric mixed transition metal oxides of spinel type were synthesized by solid state reaction technique at 973, 1073, 1173 and 1273K. Characterization of oxide samples was done by XRD and FTIR methods. The surface and catalytic properties of different samples were determined and correlated. Nickel containing oxides were found a bit more catalytically active in comparison to cobalt oxide samples. Presence of oxalate ion in sample enhances surface properties but deactivate catalytic property simultaneously. Transition metal ions i.e. Ni+2, Ni+3, Co+2 and Co+3 were mainly responsible for the activity of mixed oxides where as inner transition metal ion i.e. Pr+3 ion moderates the catalytic activities of the former. (author)

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

    KAUST Repository

    Al-Khattaf, S.

    2012-01-10

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

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

    Science.gov (United States)

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

    2014-12-16

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

  16. Catalytic ignition of light hydrocarbons

    Institute of Scientific and Technical Information of China (English)

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

    2009-01-01

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

  17. Precipitation of antimony from the solution of sodium thioantimonite by air oxidation in the presence of catalytic agents

    Institute of Scientific and Technical Information of China (English)

    杨天足; 赖琼琳; 唐建军; 楚广

    2002-01-01

    The behavior of antimony oxidation in the solution of sodium thioantimonite was studied in the presence of catalytic agents. The catalytic effects of the respective addition of cupric sulfate, sodium tartrate, potassium permanganate, phenol, 1,2-dihydroxybenzene and their combination on the oxidation of sodium thioantimonite were investigated. A pilot test was carried out. The results show that the respective use of sodium tartrate, cupric sulfate, potassium permanganate, phenol and 1,2-dihydroxybenzene have little catalytic effect on the oxidation of sodium thioantimonite. However there exists obvious catalytic oxidation by the combination of 0.25 g/L 1,2-dihydroxybenzene, 0.5 g/L potassium permanganate and 1.0 g/L phenol. Moreover, high blast intensity, the increase of temperature and NaOH concentration favor the oxidation of antimony. The oxidation process of antimony has such advantages as quick reaction and low operation costs. The results of the pilot test are consistent with those of laboratory experiments.

  18. The catalytic activity of several tungsten oxides for the oxidation of propene

    International Nuclear Information System (INIS)

    A study has been made of the catalytic oxidation of propene over the oxides WO3, WOsub(2,95), WOsub(2,90), WOsub(2,72) and Wo2, which were selected because they possess specific features of chemical and structural interest rather than for their catalytic ability. It was found that the oxides WOsub(2,95), WOsub(2,90) and WOsub(2,72) all selectively produce acrolein in small amounts. The oxides WO3 and WO2 were non-selective and rather inactive. The results are discussed in terms of a mechanism involving both variable valence in the crystal and the specific structural geometry of these compounds. (orig.)

  19. Green synthesis and synergistic catalytic effect ofAg/reduced graphene oxide nanocomposite

    Science.gov (United States)

    Hsu, Kai-Chih; Chen, Dong-Hwang

    2014-09-01

    A nanocomposite of silver nanoparticles and reduced graphene oxide (Ag/rGO) has been developed as a catalyst for the reduction of 4-nitrophenol (4-NP) to 4-aminophenol (4-AP) with sodium borohydride, owing to the larger specific surface area and synergistic effect of rGO. A facile and rapid microwave-assisted green route has been used for the uniform deposition of Ag nanoparticles and the reduction of graphene oxide simultaneously with l-arginine as the reducing agent. The resulting Ag/rGO nanocomposite contained about 51 wt% of Ag, and the Ag nanoparticles deposited on the surface of rGO had a mean diameter of 8.6 ± 3.5 nm. Also, the Ag/rGO nanocomposite exhibited excellent catalytic activity and stability toward the reduction of 4-NP to 4-AP with sodium borohydride. The reduction reaction obeyed the pseudo-first-order kinetics. The rate constants increased not only with the increase of temperature and catalyst amount but also with the increase of initial 4-NP concentration, revealing that the support rGO could enhance the catalytic activity via a synergistic effect. A mechanism for the catalytic reduction of 4-NP with NaBH4 by Ag/rGO nanocomposite via both the liquid-phase and solid-phase routes has been suggested.

  20. Catalytic conversion of carbon dioxide into dimethyl carbonate using reduced copper-cerium oxide catalysts as low as 353 K and 1.3 MPa and the reaction mechanism

    Directory of Open Access Journals (Sweden)

    Seiki eWada

    2013-06-01

    Full Text Available Synthesis of dimethyl carbonate (DMC from CO2 and methanol under milder reaction conditions was performed using reduced cerium oxide catalysts and reduced copper-promoted Ce oxide catalysts. Although the conversion of methanol was low (0.005–0.11% for 2 h of reaction, DMC was synthesized as low as 353 K and at total pressure of as low as 1.3 MPa using reduced Cu–CeO2 catalyst (0.5 wt% of Cu. The apparent activation energy was 120 kJ mol–1 and the DMC synthesis rates were proportional to the partial pressure of CO2. An optimum amount of Cu addition to CeO2 was 0.1 wt% for DMC synthesis under the conditions at 393 K and total pressure of 1.3 MPa for 2 h (conversion of methanol: 0.15% due to the compromise of two effects of Cu: the activation of H2 during reduction prior to the kinetic tests and the block (cover of the surface active site. The reduction effects in H2 were monitored through the reduction of Ce4+ sites to Ce3+ based on the shoulder peak intensity at 5727 eV in the Ce L3-edge X-ray absorption near-edge structure (XANES. The Ce3+ content was 10% for reduced CeO2 catalyst whereas it increased to 15% for reduced Cu–CeO2 catalyst (0.5wt% of Cu. Moreover, the content of reduced Ce3+ sites (10% associated with the surface O vacancy (defect sites decreased to 5% under CO2 at 290 K for reduced Cu–CeO2 catalyst (0.1wt% of Cu. The adsorption step of CO2 on the defect sites might be the key step in DMC synthesis and thus the DMC synthesis rate dependence on the partial pressure of CO2 was proportional. Subsequent H atom subtraction steps from methanol at the neighboring surface Lewis base sites should combine two methoxy species to the adsorbed CO2 to form DMC, water, and restore the surface O vacancy.

  1. Catalytic conversion of carbon dioxide into dimethyl carbonate using reduced copper-cerium oxide catalysts as low as 353 K and 1.3 MPa and the reaction mechanism

    Science.gov (United States)

    Wada, Seiki; Oka, Kazuki; Watanabe, Kentaro; Izumi, Yasuo

    2013-06-01

    Synthesis of dimethyl carbonate (DMC) from CO2 and methanol under milder reaction conditions was performed using reduced cerium oxide catalysts and reduced copper-promoted Ce oxide catalysts. Although the conversion of methanol was low (0.005-0.11%) for 2 h of reaction, DMC was synthesized as low as 353 K and at total pressure of as low as 1.3 MPa using reduced Cu-CeO2 catalyst (0.5 wt% of Cu). The apparent activation energy was 120 kJ mol-1 and the DMC synthesis rates were proportional to the partial pressure of CO2. An optimum amount of Cu addition to CeO2 was 0.1 wt% for DMC synthesis under the conditions at 393 K and total pressure of 1.3 MPa for 2 h (conversion of methanol: 0.15%) due to the compromise of two effects of Cu: the activation of H2 during reduction prior to the kinetic tests and the block (cover) of the surface active site. The reduction effects in H2 were monitored through the reduction of Ce4+ sites to Ce3+ based on the shoulder peak intensity at 5727 eV in the Ce L3-edge X-ray absorption near-edge structure (XANES). The Ce3+ content was 10% for reduced CeO2 catalyst whereas it increased to 15% for reduced Cu-CeO2 catalyst (0.5wt% of Cu). Moreover, the content of reduced Ce3+ sites (10%) associated with the surface O vacancy (defect sites) decreased to 5% under CO2 at 290 K for reduced Cu-CeO2 catalyst (0.1wt% of Cu). The adsorption step of CO2 on the defect sites might be the key step in DMC synthesis and thus the DMC synthesis rate dependence on the partial pressure of CO2 was proportional. Subsequent H atom subtraction steps from methanol at the neighboring surface Lewis base sites should combine two methoxy species to the adsorbed CO2 to form DMC, water, and restore the surface O vacancy.

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

    Science.gov (United States)

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

    2016-06-01

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

  3. A PROCESS FOR THE CATALYTIC OXIDATION OF HYDROCARBONS

    DEFF Research Database (Denmark)

    1999-01-01

    A process for producing an alcohol from a gaseous hydrocarbon, e.g. a lower alkane such as methane, via oxidative reaction of the hydrocarbon in a concentrated sulfuric acid medium in the presence of a catalyst employs an added catalyst comprising a substance selected from iodine, iodine compounds...

  4. Catalytic oxidation of calcium sulfite in solution/aqueous slurry

    Institute of Scientific and Technical Information of China (English)

    WU Xiao-qin; WU Zhong-biao; WANG Da-hui

    2004-01-01

    Forced oxidation of calcium sulfite aqueous slurry is a key step for the calcium-based flue gas desulfurization(FGD) residue. Experiments were conducted in a semi-batch system and a continuous flow system on lab scales. The main reactor in semi-batch system is a 1000 ml volume flask. It has five necks for continuous feeding of gas and a batch of calcium sulfite solution/aqueous slurry. In continuous flow system, the main part is a jacketed Pyrex glass reactor in which gas and solution/aqueous slurry are fed continuously. Calcium sulfite oxidation is a series of complex free-radical reactions. According to experimental results and literature data, the reactions are influenced significantly by manganese as catalyst. At low concentration of manganese and calcium sulfite, the reaction rate is dependent on 1.5 order of sulfite concentration, 0.5 order of manganese concentration, and zero order of oxygen concentration in which the oxidation is controlled by chemical kinetics. With concentrations of calcium sulfite and manganese increasing, the reactions are independent gradually on the constituents in solution but are impacted by oxygen concentration. Manganese can accelerate the free-radical reactions, and then enhances the mass transfer of oxygen from gas to liquid. The critical concentration of calcium sulfite is 0.007 mol/L, manganese is 10-4 mol/L, and oxygen is of 0.2-0.4 atm.

  5. Catalytic performance of Fe-ZSM-5 catalysts for selective catalytic reduction of nitric oxide by ammonia

    Energy Technology Data Exchange (ETDEWEB)

    Long, R.Q.; Yang, R.T.

    1999-12-10

    A series of Fe-exchanged molecular sieves were studied as catalysts for the selective catalytic reduction (SCR) of NO with ammonia. It was found that Fe-ZSM-5 and Fe-mordenite catalysts were highly active for the SCR reaction. Nearly 100% NO conversions were obtained at 400--500 C under conditions with a high space velocity (GHSV = 4.6 x 10{sup 5} 1/h). However, Fe-Y and Fe-MCM-41 with larger pore sizes showed lower activities for this reaction. F or Fe-ZSM-5 catalysts, the SCR activity decreased with increasing Si/Al ratio in the zeolites. As the Fe-exchange level in the Fe-ZSM-5 catalysts was increased from 58 to 252%, NO conversion increased at lower temperatures (e.g., 300 C), but decreased at high temperatures (e.g., 600 C). Compared with the commercial vanadia catalyst, based on the first-order rate constants, the Fe-ZSM-5 catalyst was five times more active at 400 C and seven times more active at 450 C. It also functioned in a broader temperature window, produced only N{sub 2} (rather than N{sub 2}O) and H{sub 2}O, and showed a substantially lower activity for oxidation of SO{sub 2} to SO{sub 3}.

  6. Facile synthesis of clean Pt nanoparticles supported on reduced graphene oxide composites: Their growth mechanism and tuning of their methanol electro-catalytic oxidation property

    International Nuclear Information System (INIS)

    A facile hydrothermal method has been proposed to prepare reduced graphene oxide (RGO) and enhance its reducing ability. For the first time, the spontaneous redox reaction between PtCl42− and RGO has been reported and no additional reductants or surfactants were needed. X-ray photoelectron spectroscopy and transmission electron microscope images were used to characterize the synthesized Pt nanoparticles supported on RGO sheet (PtNPs/RGO) composites. The reaction mechanism has been investigated by changing the medium pH of the reaction. We further proved that the electro-catalytic property of PtNPs/RGO could be tuned and, because of the clean, well-dispersed PtNPs and the synergistic effect between the PtNPs and RGO, the PtNPs/RGO expressed higher electro-catalytic activity and better tolerance for methanol oxidization than a commercial Pt/C catalyst

  7. Gas phase heterogeneous catalytic oxidation of alkanes to aliphatic ketones and/or other oxygenates

    Energy Technology Data Exchange (ETDEWEB)

    Lin, Manhua; Wang, Xiang; Yeom, Younghoon

    2015-09-29

    A catalyst, its method of preparation and its use for producing aliphatic ketones by subjecting alkanes C.sub.3 to C.sub.9 to a gas phase catalytic oxidation in the presence of air or oxygen, and, optionally, steam and/or one or more diluting gases. The catalyst comprises a catalytically active mixed metal oxide phase and a suitable support material onto and/or into which the active catalytic phase is dispersed.

  8. Gas phase heterogeneous catalytic oxidation of alkanes to aliphatic ketones and/or other oxygenates

    Science.gov (United States)

    Lin, Manhua; Wang, Xiang; Yeom, Younghoon

    2015-03-17

    A catalyst, its method of preparation and its use for producing aliphatic ketones by subjecting alkanes C.sub.3 to C.sub.9 to a gas phase catalytic oxidation in the presence of air or oxygen, and, optionally, steam and/or one or more diluting gases. The catalyst comprises a catalytically active mixed metal oxide phase and a suitable support material onto and/or into which the active catalytic phase id dispersed.

  9. Catalytic properties and biomedical applications of cerium oxide nanoparticles

    KAUST Repository

    Walkey, Carl D.

    2014-11-10

    Cerium oxide nanoparticles (nanoceria) have shown promise as catalytic antioxidants in the test tube, cell culture models and animal models of disease. However given the reactivity that is well established at the surface of these nanoparticles, the biological utilization of nanoceria as a therapeutic still poses many challenges. Moreover the form that these particles take in a biological environment, such as the changes that can occur due to a protein corona, are not well established. This review aims to summarize the existing literature on biological use of nanoceria, and to raise questions about what further study is needed to apply this interesting catalytic material to biomedical applications. These questions include: 1) How does preparation, exposure dose, route and experimental model influence the reported effects of nanoceria in animal studies? 2) What are the considerations to develop nanoceria as a therapeutic agent in regards to these parameters? 3) What biological targets of reactive oxygen species (ROS) and reactive nitrogen species (RNS) are relevant to this targeting, and how do these properties also influence the safety of these nanomaterials?

  10. Solid state and catalytic CO oxidation studies on Zn1-xNixMnO3 system

    International Nuclear Information System (INIS)

    Nickel-substituted zinc manganite compositions Zn1-xNixMnO3 (x = 0.0, 0.2, 0.4. 0.6, 0.8 and 1.0) with perovskite structure were prepared by co-precipitation precursor method and characterized by X-ray diffraction, infrared spectroscopy, atomic absorption spectroscopy, surface area measurement and thermal techniques. These compounds were tested for the model catalytic reaction of carbon monoxide oxidation. Attempts were made to correlate the solid state and spectroscopic studies of the compositions with their catalytic activities

  11. Oscillatory Behavior during the Catalytic Partial Oxidation of Methane: Following Dynamic Structural Changes of Palladium Using the QEXAFS Technique

    OpenAIRE

    Stoetzel, Jan; Frahm, Ronald; Kimmerle, Bertram; Nachtegaal, Maarten; Grunwaldt, Jan-Dierk

    2012-01-01

    Pd/Al2O3 catalysts oscillate between ignition and extinction of the catalytic partial oxidation of methane when they are exposed to a 2:1 reaction mixture of methane and oxygen. The oscillations of the catalytic performance and the structure of Pd/Al2O3 catalysts in a fixed-bed reactor were investigated using spatially and time-resolved in situ quick scanning X-ray absorption spectroscopy with online mass spectrometry. The dynamic methane conversion oscillated between an inactive state, where...

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

    Science.gov (United States)

    Pang, Simon H; Medlin, J Will

    2015-04-16

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

  13. Methylene Blue Inhibits Caspases by Oxidation of the Catalytic Cysteine.

    Science.gov (United States)

    Pakavathkumar, Prateep; Sharma, Gyanesh; Kaushal, Vikas; Foveau, Bénédicte; LeBlanc, Andrea C

    2015-01-01

    Methylene blue, currently in phase 3 clinical trials against Alzheimer Disease, disaggregates the Tau protein of neurofibrillary tangles by oxidizing specific cysteine residues. Here, we investigated if methylene blue can inhibit caspases via the oxidation of their active site cysteine. Methylene blue, and derivatives, azure A and azure B competitively inhibited recombinant Caspase-6 (Casp6), and inhibited Casp6 activity in transfected human colon carcinoma cells and in serum-deprived primary human neuron cultures. Methylene blue also inhibited recombinant Casp1 and Casp3. Furthermore, methylene blue inhibited Casp3 activity in an acute mouse model of liver toxicity. Mass spectrometry confirmed methylene blue and azure B oxidation of the catalytic Cys163 cysteine of Casp6. Together, these results show a novel inhibitory mechanism of caspases via sulfenation of the active site cysteine. These results indicate that methylene blue or its derivatives could (1) have an additional effect against Alzheimer Disease by inhibiting brain caspase activity, (2) be used as a drug to prevent caspase activation in other conditions, and (3) predispose chronically treated individuals to cancer via the inhibition of caspases. PMID:26400108

  14. Mercury Oxidation via Catalytic Barrier Filters Phase II

    Energy Technology Data Exchange (ETDEWEB)

    Wayne Seames; Michael Mann; Darrin Muggli; Jason Hrdlicka; Carol Horabik

    2007-09-30

    In 2004, the Department of Energy National Energy Technology Laboratory awarded the University of North Dakota a Phase II University Coal Research grant to explore the feasibility of using barrier filters coated with a catalyst to oxidize elemental mercury in coal combustion flue gas streams. Oxidized mercury is substantially easier to remove than elemental mercury. If successful, this technique has the potential to substantially reduce mercury control costs for those installations that already utilize baghouse barrier filters for particulate removal. Completed in 2004, Phase I of this project successfully met its objectives of screening and assessing the possible feasibility of using catalyst coated barrier filters for the oxidation of vapor phase elemental mercury in coal combustion generated flue gas streams. Completed in September 2007, Phase II of this project successfully met its three objectives. First, an effective coating method for a catalytic barrier filter was found. Second, the effects of a simulated flue gas on the catalysts in a bench-scale reactor were determined. Finally, the performance of the best catalyst was assessed using real flue gas generated by a 19 kW research combustor firing each of three separate coal types.

  15. Dynamics of ultrathin V-oxide layers on Rh(111) in catalytic oxidation of ammonia and CO.

    Science.gov (United States)

    von Boehn, B; Preiss, A; Imbihl, R

    2016-07-20

    Catalytic oxidation of ammonia and CO has been studied in the 10(-4) mbar range using a catalyst prepared by depositing ultra-thin vanadium oxide layers on Rh(111) (θV ≈ 0.2 MLE). Using photoemission electron microscopy (PEEM) as a spatially resolving method, we observe that upon heating in an atmosphere of NH3 and O2 the spatial homogeneity of the VOx layer is removed at 800 K and a pattern consisting of macroscopic stripes develops; at elevated temperatures this pattern transforms into a pattern of circular VOx islands. Under reaction conditions the neighboring VOx islands become attracted by each other and coalesce. Similar processes of pattern formation and island coalescence are observed in catalytic CO oxidation. Reoxidation of the reduced VOx catalyst proceeds via surface diffusion of oxygen adsorbed onto Rh(111). A pattern consisting of macroscopic circular VOx islands can also be obtained by heating a Rh(111)/VOx catalyst in pure O2. PMID:27380822

  16. On the catalytic gas phase oxidation of butadiene to furan

    Energy Technology Data Exchange (ETDEWEB)

    Kubias, B.; Rodemerck, U. [Institut fuer Angewandte Chemie Berlin-Adlershof e.V., Berlin (Germany); Ritschl, F.; Meisel, M. [Humboldt-Universitaet, Berlin (Germany). Inst. fuer Chemie

    1998-12-31

    Applying the thermochemical selectivity criterion of Hadnett et al. It is shown that the selectivity of the furan formation is not limited by a too low strength of the C-H bonds in furan when compared with the C-H bond dissociation energy in the educt molecule butadiene. In the oxidation of butadiene on a CsH{sub 2}PMo{sub 12}O{sub 40} catalyst a maximum yield of 22 mol% furan has been obtained. To improve this comparatively low furan yield oxidation activity of the catalyst must be lowered to prevent the consecutive reaction to maleic anhydride. (orig.)

  17. Characterization of microstructure and catalytic of cerium oxide obtained by colloidal solution

    International Nuclear Information System (INIS)

    This study investigated to obtain particles of cerium oxide, for use as catalysts for the combustion of methane using the technique of through polymeric colloidal solution. Obtaining the colloidal system is based on hydrolysis of salts such as cerium acetylacetonate, cerium nitrate in the presence of additives such as polyvinylbutyral (PVB), polyvinylpyrrolidone (PVP) and polyvinyl acetate (PVA), at concentrations of 5, 10 and 15% in aqueous or alcoholic medium. These solutions containing ions of interest were subjected to a heat treatment at 650° C for 30 minutes, with heating rate of 2 ° C/ min. After heat treatment, the fibers were characterized according to their morphology, surface area, crystallinity, weight loss and catalytic activity. Samples obtained from cerium acetylacetonate were more reactive than the cerium nitrate to the combustion of methane, as showed greater conversions and higher temperatures reached during the process, which is of utmost importance since the combustion catalytic methane is used for generating thermal energy. After the reaction with methane, the samples underwent significant change in surface area, probably due to the intensity of combustion reactions of the nitrate and the generation of heat involved in this reaction, which gave rise to coarse particles. During the combustion process using the obtained from particles of cerium acetylacetonate, there was the release of large quantities of nitrogen compared to the results of assays with the particles obtained with cerium nitrate. (author)

  18. Graphene oxide supported Au–Ag alloy nanoparticles with different shapes and their high catalytic activities

    International Nuclear Information System (INIS)

    A simple method was developed to fabricate Au–Ag nanoparticle/graphene oxide nanocomposites (Au–Ag/GO) by using simultaneous redox reactions between AgNO3, HAuCl4 and GO. The Au–Ag/GO was characterized by x-ray photoelectron spectroscopy, transmission electron microscopy and energy dispersive x-ray spectroscopy. The GO nanosheets acted as the reducing agent and the support for the Au–Ag alloy nanoparticles. In addition, Au–Ag alloy nanoparticles with different shapes including core–shell-like, dendrimer-like and flower-like were obtained by simply modifying the concentration of the reactants and the reaction temperature. With no reducing or stabilizing agents added, the Au–Ag/GO nanocomposites show superior catalytic performance for the reduction of 4-nitrophenol and for the aerobic homocoupling of phenylboronic acid. (paper)

  19. Catalytic wet peroxide oxidation of phenol solutions over CuO/CeO2 systems

    International Nuclear Information System (INIS)

    Three 5% CuO/CeO2 catalysts were synthesized by sol-gel, precipitation and combustion methods, followed by incipient wetness impregnation with copper nitrate. The samples were characterized by XRD, TPR, BET and tested for the catalytic wet peroxide oxidation of a phenol solution (5 g/L). The reaction took place in a batch reactor at atmospheric pressure, in a temperature range of 60-80°C , during 4 h. Phenol conversion, H2O2 consumption, pH and chemical oxygen demand were determined. The reaction temperature and the catalyst loading did improve the phenol and the H2O2 conversions. The effect on the selectivity towards complete mineralization was less marked, with levels among 60-70%. Stepwise addition of H2O2 was also tested.

  20. Study of the catalytic activity of pure or cerium-containing thoria in the catalytic oxidation of carbon monoxide (1963)

    International Nuclear Information System (INIS)

    We have undertaken research into the oxidation of carbon monoxide on pure thoria prepared by the decomposition of thorium nitrate, and on the same oxide containing small amounts of cerium. The results we have obtained, both as concerns the chemisorption of the various gases as well as the conductivity of the absorbent and the kinetics of the oxidation itself, appear to be quite coherent. The following steps occur: 1) The carbon monoxide is adsorbed on a clean catalyst surface, the oxygen remaining un-adsorbed. 2) The oxygen is adsorbed on a previously adsorbed carbon, monoxide layer, and reacts to give carbon dioxide (no role being played by the lattice oxygen). This behaviour is usual for a p-type semiconductor. We have in fact confirmed that semi-conductivity is of this type, and the gas-solid interactions can be written: (1) CO(g) ↔ CO+(a) + e- (2) CO+ 1/2 O2(g) + 2 e- → CO-2(a) (3) CO-2(a) ↔ CO2(g) + e- The kinetic equation obtained by supposing that step (2) is the slowest, makes it possible to deduce correctly the experimental results which can be expressed as: dp / dt = k (P0.3CO x P0.5O2) / (1+ k' x PCO2) The influence of the addition of small amounts of cerium can also be explained logically by this process; there is in fact both a decrease in the conductivity and an increase in the catalytic activity, this being characteristic, according to VOLKENSTEIN [52] of an n-type rate-determining reaction occurring on a p-type semi-conductor. We believe that these first results could be advantageously complemented by a study of thoria prepared by other means and doped differently. (author)

  1. Effects of Gas Velocity and Temperature on Nitric Oxide Conversion in Simulated Catalytic Converter

    Directory of Open Access Journals (Sweden)

    Sathaporn Chuepeng

    2012-01-01

    Full Text Available Problem statement: Gaseous emissions from gasoline engine such as carbon monoxide, unburned hydrocarbon and nitrogen oxides were usually reduced in three-way catalytic converter simultaneously around theoretical fuel and air combustion. Engine speed and load and other parameters were varied over a wide range of operating conditions, resulting in different exhaust gas composition and condition intake into catalytic converter. This work was studied the conversion of Nitric Oxide (NO in exhaust gas catalytic converter affected by gas velocity and inlet temperature using numerical modeling. Approach: The simulation was based on a one-dimensional time-dependent model within a single monolith channel of the converter. Upon certain assumptions, the study was considered heterogeneous combustion reaction between gas and solid phases based on lumped kinetic reactions. In this study, constants and variables used for mass and heat transfers were dependent on gas or solid phase temperature and mole fraction. Finite difference scheme incorporated with the generated computer code was established for solving species and energy balances within gas and solid phases. Results: The NO conversion was increased with transient period in initial and reached steady state at different values. The lower inlet gas temperature was resulted in lesser NO conversion at the same inlet NO concentration and gas velocity. The light-off temperatures were up to 520 K and a sudden rise in NO conversion was from 550-605 K and decreasing onwards, generating working temperature window. NO conversion increased throughout the catalyst bed from the inlet and the conversion decreased as the gas velocity increased. Conclusion/Recommendations: Gas space velocity and gas temperature intake to the converter affected the NO conversion over the time and the axial distance from the catalyst bed inlet. The numerical results have summarily demonstrated a good approximation compared to experimental

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

    Science.gov (United States)

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

    2010-08-03

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

  3. Rare earth oxide aero- and xerogels. Tuning porosity and catalytic properties

    International Nuclear Information System (INIS)

    Heterogeneous catalysts to this day are still largely developed on the basis of trial and error. This is due to the great difficulty of creating custom-designed structures at the nanometer scale using traditional preparation methods. In the course of recent rapid developments in the material sciences, however, it has become possible to create materials with custom-designed properties from the macroscopic down into the nanometer range. The purpose of the present study was to make use of this potential for catalysis. The task was to modify the porosity and composition of selected rare earth oxides that promise well as catalysts with the goal of obtaining good results in terms of oxidative reactions and oxidative coupling. One major focus was on chemical sol-gel methods and in particular on what is referred to as the epoxide addition method. Extensive work was put into the characterisation and catalytic testing of aerogels and xerogels of pure rare earth oxides as well as of hybrid systems of rare earth oxides and aluminium oxide. Furthermore, thin xerogel films and macroporous monoliths were produced, the latter using a direct foaming method. The results of this work confirm the high potential of sol-gel chemistry for making porous materials of variable and controllable porosity and composition available for heterogeneous catalysis and creating more powerful catalysts.

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

    KAUST Repository

    Hisatomi, Takashi

    2014-10-16

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

  5. Catalytic oxidative conversion of alkanes to olefines and oxygenates

    Energy Technology Data Exchange (ETDEWEB)

    Baerns, M. [Institut fuer Angewandte Chemie Berlin-Adlershof e.V., Berlin (Germany)

    1998-12-31

    All of the direct reaction schemes described and the corresponding process schemes are still in an exploratory state. Ethylene by oxidative coupling of methane could become competitive if process schemes are developed with significantly less expenditures for separation of the product from unconverted feed. No encouragement for formaldehyde from methane can be presently derived from the existing knowledge. Liquid-phase oxidation of methane to methanol appears to be attractive but no final judgement is possible at present. Oxidative dehydrogenation of ethylene and propane look promising although further catalyst improvement is required. Acetic acid from ethane and acrylonitrile from propane have a certain potential as an alternative to present technology. The outlook for acrolein and acrylic acid from propane is less favourable; new concepts for catalyst design are necessary. (orig.)

  6. Manganese chlorins immobilized on silica as oxidation reaction catalysts.

    Science.gov (United States)

    Castro, Kelly A D F; Pires, Sónia M G; Ribeiro, Marcos A; Simões, Mário M Q; Neves, M Graça P M S; Schreiner, Wido H; Wypych, Fernando; Cavaleiro, José A S; Nakagaki, Shirley

    2015-07-15

    Synthetic strategies that comply with the principles of green chemistry represent a challenge: they will enable chemists to conduct reactions that maximize the yield of products with commercial interest while minimizing by-products formation. The search for catalysts that promote the selective oxidation of organic compounds under mild and environmentally friendly conditions constitutes one of the most important quests of organic chemistry. In this context, metalloporphyrins and analogues are excellent catalysts for oxidative transformations under mild conditions. In fact, their reduced derivatives chlorins are also able to catalyze organic compounds oxidation effectively, although they have been still little explored. In this study, we synthesized two chlorins through porphyrin cycloaddition reactions with 1.3-dipoles and prepared the corresponding manganese chlorins (MnCHL) using adequate manganese(II) salts. These MnCHL were posteriorly immobilized on silica by following the sol-gel process and the resulting solids were characterized by powder X-ray diffraction (PXRD), UVVIS spectroscopy, FTIR, XPS, and EDS. The catalytic activity of the immobilized MnCHL was investigated in the oxidation of cyclooctene, cyclohexene and cyclohexane and the results were compared with the ones obtained under homogeneous conditions. PMID:25841060

  7. Catalytic application of an organosuperbasedenderon grafted on mesoporous SBA-15 and related palladium complex in the aerobic oxidation of alcohols

    Directory of Open Access Journals (Sweden)

    Hojat Veisi

    2014-02-01

    Full Text Available An efficient synthetic method for successful application of amine denderon on SBA-15 and related Pd (II complex has been developed by employing aerobic oxidation of alcohols as model reactions. The yields of the products were in the range from 75% to 92%. The catalyst can be readily recovered and reused at least 5 consecutive cycles without significant leaching and loss its catalytic activity.

  8. Facile synthesis of magnetically separable reduced graphene oxide/magnetite/silver nanocomposites with enhanced catalytic activity.

    Science.gov (United States)

    Ji, Zhenyuan; Shen, Xiaoping; Yue, Xiaoyang; Zhou, Hu; Yang, Juan; Wang, Yuqin; Ma, Lianbo; Chen, Kangmin

    2015-12-01

    In this study, the combination of magnetite (Fe3O4) with reduced graphene oxide (RGO) generates a new hybrid substrate for the dispersion of noble metal nanoparticles. Well-dispersed silver (Ag) nanoparticles loaded on the surface of Fe3O4 modified RGO are achieved by an efficient two-step approach. Through reducing Ag(+) ions, highly dispersed Ag nanoparticles are in-situ formed on the RGO/Fe3O4 substrate. It is found that the existence of Fe3O4 nanocrystals can significantly improve the dispersity and decrease the particle size of the in-situ formed Ag nanoparticles. Magnetic study reveals that the as-prepared RGO/Fe3O4/Ag ternary nanocomposites display room-temperature superparamagnetic behavior. The catalytic properties of the RGO/Fe3O4/Ag ternary nanocomposites were evaluated with the reduction of 4-nitrophenol into 4-aminophenol as a model reaction. The as-synthesized RGO/Fe3O4/Ag ternary catalysts exhibit excellent catalytic stability and much higher catalytic activity than the corresponding RGO/Ag catalyst. Moreover, the RGO/Fe3O4/Ag catalysts can be easily magnetically separated for reuse. This study further demonstrates that nanoparticles modified graphene can act as an effective hybrid substrate for the synthesis of multi-component and multifunctional graphene-based composites. PMID:26263498

  9. Radiation influencing of catalytic activity and reactivity of selected mixed oxides

    International Nuclear Information System (INIS)

    Two mixed oxides, viz. CuO-Bi2O3 and NiO-Bi2O3, of various compositions were studied with respect to their physico-chemical properties, catalytic activity, and chemical reactivity, using hydrogen peroxide decomposition and hydrogen reduction as the test reactions. Pre-irradiation of the CuO-Bi2O3 catalyst with 60Co gamma rays (0.5, 1.0, 1.5, or 3.0 MGy) and accelerated electrons (4 MeV) brought about changes in the mutual influence of the system components accompanied by formation of induced catalytic sites. The reduction rate decrease in the two side regions after electron irradiation and after gamma irradiation applying the extremely high dose of 3 MGy can be correlated with the increase in the concentration of the strongly bonded oxygen forms, giving rise to centres for donor hydrogen chemisorption. The NiO-Bi2O3 system seems to be less stable than the CuO-Bi2O3 system. Gamma irradiation (1 MGy) in water brought about decrease in the catalytic activity but no change in the mutual influence of the two components of the system. In the same conditions the reduction rate decreased appreciably, whereas pre-irradiation in air led to acceleration of the reduction process. This can be ascribed to a higher concentration of the stabilized charge defects, enhancing the reactivity of the interface. (author). 4 figs., 6 refs

  10. Catalytic propane dehydrogenation over In₂O₃–Ga₂O₃ mixed oxides

    Energy Technology Data Exchange (ETDEWEB)

    Tan, Shuai; Gil, Laura Briones; Subramanian, Nachal; Sholl, David S.; Nair, Sankar; Jones, Christopher W.; Moore, Jason S.; Liu, Yujun; Dixit, Ravindra S.; Pendergast, John G. (Dow); (GIT)

    2015-08-26

    We have investigated the catalytic performance of novel In₂O₃–Ga₂O₃ mixed oxides synthesized by the alcoholic-coprecipitation method for propane dehydrogenation (PDH). Reactivity measurements reveal that the activities of In₂O₃–Ga₂O₃ catalysts are 1–3-fold (on an active metal basis) and 12–28-fold (on a surface area basis) higher than an In₂O₃–Al₂O₃ catalyst in terms of C₃H₈ conversion. The structure, composition, and surface properties of the In₂O₃–Ga₂O₃ catalysts are thoroughly characterized. NH₃-TPD shows that the binary oxide system generates more acid sites than the corresponding single-component catalysts. Raman spectroscopy suggests that catalysts that produce coke of a more graphitic nature suppress cracking reactions, leading to higher C₃H₆ selectivity. Lower reaction temperature also leads to higher C₃H₆ selectivity by slowing down the rate of side reactions. XRD, XPS, and XANES measurements, strongly suggest that metallic indium and In₂O₃ clusters are formed on the catalyst surface during the reaction. The agglomeration of In₂O₃ domains and formation of a metallic indium phase are found to be irreversible under O₂ or H₂ treatment conditions used here, and may be responsible for loss of activity with increasing time on stream.

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

    Science.gov (United States)

    Sharma, Himanshu; Vasu, Nadapana; de, Sirshendu

    2011-05-01

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

  12. CuO impregnated activated carbon for catalytic wet peroxide oxidation of phenol

    International Nuclear Information System (INIS)

    This paper presents an original approach to the removal of phenol in synthetic wastewater by catalytic wet peroxide oxidation with copper binding activated carbon (CuAC) catalysts. The characteristics and oxidation performance of CuAC in the wet hydrogen peroxide catalytic oxidation of phenol were studied in a batch reactor at 80 deg. C. Complete conversion of the oxidant, hydrogen peroxide, was observed with CuAC catalyst in 20 min oxidation, and a highly efficient phenol removal and chemical oxygen demand (COD) abatement were achieved in the first 30 min. The good oxidation performance of CuAC catalyst was contributed to the activity enhancement of copper oxide, which was binding in the carbon matrix. It can be concluded that the efficiency of oxidation dominated by the residual H2O2 in this study. An over 90% COD removal was achieved by using the multiple-step addition in this catalytic oxidation.

  13. Low temperature catalytic decomposition and oxidation of MTBE

    International Nuclear Information System (INIS)

    Catalytic combustion of methyl-tert-butyl-ether (MTBE) was studied in the gas-phase from an aqueous solution spiked with MTBE (1.1mM), to simulate actual remediation conditions. The solution of MTBE was sparged with an oxygen/helium gas, at a ratio of 1-4. The sparged gas stream of MTBE and water vapor was passed over catalysts utilizing Pt/Rh or Pd in conjunction with a mixed metal oxide based upon La1-xSrxMnO3. The results were compared to a commercial catalyst which contained a higher loading of Pt. The experiments with the catalysts were conducted over a temperature range of 80-500C. Combustion to CO2 and water was observed in all cases, but by-product formation of isobutene and methanol was seen at lower temperatures for all of the catalysts tested, with the exception of the commercial catalyst. The catalyst with the lowest loading of Pt/Rh achieved the lowest temperature for complete oxidation of MTBE and its by-products

  14. Development of Ag dendrites-reduced graphene oxide composite catalysts via galvanic replacement reaction

    Science.gov (United States)

    Fu, Li; Sokiransky, Mika Matsunaka; Wang, James; Lai, Guosong; Yu, Aimin

    2016-09-01

    Silver dendrites/reduced graphene oxide (AgD/RGO) composites were synthesized via a facile galvanic replacement method. The successful formation of Ag dendrites and the graphene oxide reduction were proved by a series of characterization techniques. The possible formation mechanism of Ag dendrites during the galvanic replacement reaction was discussed. The catalytic activity of the as-synthesized AgD/RGO composite was evaluated by its performance on the chemical reduction of an organic dye methylene blue. The AgD/RGO composite showed a much higher catalytic performance and stability than that of Ag dendrites.

  15. Co-Containing Mixed Oxides and Their Activity in Catalytic Decomposition of Nitrous Oxide

    Czech Academy of Sciences Publication Activity Database

    Obalová, L.; Jirátová, Květa; Kovanda, F.; Pacultová, K.; Lacný, Z.; Mikulová, Z.

    Praha : Process Engineering Publisher, 2004. s. 332. ISBN 80-86059-40-5. [International Congress of Chemical and Process Engineering CHISA 2004 /16./. 22.08.2004-26.08.2004, Praha] R&D Projects: GA ČR GA104/04/2116 Institutional research plan: CEZ:AV0Z4072921 Keywords : catalytic decomposition * mixed oxide s Subject RIV: CI - Industrial Chemistry, Chemical Engineering

  16. Synthesis, characterization, and catalytic application of ordered mesoporous carbon–niobium oxide composites

    Energy Technology Data Exchange (ETDEWEB)

    Gao, Juan-Li; Gao, Shuang; Liu, Chun-Ling; Liu, Zhao-Tie; Dong, Wen-Sheng, E-mail: wsdong@snnu.edu.cn

    2014-11-15

    Graphical abstract: The ordered mesoporous carbon–niobium oxide composites have been synthesized by a multi-component co-assembly method associated with a carbonization process. - Highlights: • Ordered mesoporous carbon–niobium oxide composites were synthesized. • The content of Nb{sub 2}O{sub 5} in the composites could be tuned from 38 to 75%. • Niobium species were highly dispersed in amorphous carbon framework walls. • The composites exhibited good catalytic performance in the dehydration of fructose. - Abstract: Ordered mesoporous carbon–niobium oxide composites have been synthesized by a multi-component co-assembly method associated with a carbonization process using phenolic resol as carbon source, niobium chloride as precursor and amphiphilic triblock copolymer Pluronic F127 as template. The resulting materials were characterized using a combination of techniques including differential scanning calorimetry–thermogravimetric analysis, N{sub 2} physical adsorption, X-ray diffraction, transmission electron microscopy, and X-ray photoelectron spectroscopy. The results show that with increasing the content of Nb{sub 2}O{sub 5} from 38 to 75% the specific surface area decreases from 306.4 to 124.5 m{sup 2} g{sup −1}, while the ordered mesoporous structure is remained. Niobium species is well dispersed in the amorphous carbon framework. The mesoporous carbon–niobium oxide composites exhibit high catalytic activity in the dehydration of fructose to 5-hydroxymethylfurfural. A 100% conversion of fructose and a 76.5% selectivity of 5-hydroxymethylfurfural were obtained over the carbon–niobium oxide composite containing 75% Nb{sub 2}O{sub 5} under the investigated reaction conditions.

  17. Catalytic wet oxidation of ammonia solution: Activity of the nanoscale platinum-palladium-rhodium composite oxide catalyst

    International Nuclear Information System (INIS)

    Aqueous solutions of 400-1000 mg/L of ammonia were oxidized in a trickle-bed reactor (TBR) in this study of nanoscale platinum-palladium-rhodium composite oxide catalysts, which were prepared by the co-precipitation of H2PtCl6, Pd(NO3)3 and Rh(NO3)3. Hardly any of the dissolved ammonia was removed by wet oxidation in the absence of any catalyst, whereas about 99% of the ammonia was reduced during wet oxidation over nanoscale platinum-palladium-rhodium composite oxide catalysts at 503 K in an oxygen partial pressure of 2.0 MPa. A synergistic effect exists in the nanoscale platinum-palladium-rhodium composite structure, which is the material with the highest ammonia reduction activity. The nanometer-sized particles were characterized by TEM, XRD and FTIR. The effect of the initial concentration and reaction temperature on the removal of ammonia from the effluent streams was also studied at a liquid hourly space velocity of under 9 h-1 in the wet catalytic processes

  18. Physicochemical properties and catalytic activity of metal tetraphenyl porphins in the oxidation of alkylaromatic hydrocarbons

    Science.gov (United States)

    Kobotaeva, N. S.; Skorokhodova, T. S.; Kokova, D. A.

    2013-06-01

    We consider the effect of complexing metal in a tetraphenylporphin molecule on its catalytic activity in oxidizing alkylaromatic hydrocarbons by molecular oxygen. The catalytic activity of metal porphyrins (Co, Cu, Zn, Mn, and In TPP) is found to depend on their oxidation potentials and the distribution of electron density in the molecule. The electron-donating compound imidazole is shown to affect the oxidation rate.

  19. Key parameters when developing carbonaceous materials for catalytic wet peroxide oxidation

    OpenAIRE

    Ribeiro, Rui; Silva, Adrián; Pastrana-Martínez, Luisa; Figueiredo, José; Faria, Joaquim; Gomes, Helder

    2014-01-01

    Catalytic wet peroxide oxidation (CWPO) is an advanced oxidation process, operated using simple equipment and mild operating conditians, in which highly oxidizing hydraxyl radicaIs (HO') are generated fram the catalytic decompasition af hydrogen peroxide (H,O,) [L 2). Sinee the report of Lüeking el ai. in 1998 [3], the develapment af suitab-Ie -carbonaceous materials (without any added metal phase) for CWPO has been intensively explored [4). lhe influenee of struetUfal and surr...

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

    Directory of Open Access Journals (Sweden)

    Xiaoqing Zhang

    2013-01-01

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

  1. Role of iron oxide catalysts in selective catalytic reduction of NOx and soot from vehicular emission

    International Nuclear Information System (INIS)

    This study deals with Iron containing catalysts i.e Iron oxide Fe/sub 2/O/sub 3/) Iron potassium oxide Fe/sub 1.9/K/sub 0.1/O/sub 3/, copper iron oxide Cu/sub 0.9/K/sub 0.1/, Fe/sub 2/O/sub 3/, nickel iron oxide Ni Fe/sub 2/O/sub 4/, and Nickel potassium iron oxide Ni/sub 0.95/K/sub 0.05/ Fe/sub 2/O/sub 4/ catalyst were synthesized by using PVA technique. By X-ray Diffraction technique these catalysts were characterized to ensure the formation of crystalline structure. Energy Dispersive X-rays analysis (EDX) was used for the confirmation of presence of different metals and Scanning Electron Microscopy (SEM) for Surface Morphology. Then the catalytic investigations of the prepared catalyst were carried out for their activity measurement toward simultaneous conversion of NOx and Soot from an engine exhaust. Some Iron containing oxide catalysts were partially modified by alkali metal potassium and were used for NOx -Soot reaction in a model exhaust gas. Fe/sub 1.9 K /sub 0.1/O/sub 3/ show high catalytic performance for N/sub 2/ formation in the prepared catalyst. Further studies have shown that Fe/sub 1.9/ K/sub 0.1/ O/sub 3/ was deactivated in a substantial way after about 20 Temperature. Temperature Programmed Reaction (TPR) experiments due to agglomeration of the promoter potassium. Experiments carried out over the aged Fe/sub 1.9/K/sub 0.1/O/sub 3/ catalyst have shown that NOx-soot reaction was suppressed at higher oxygen concentration, since O/sub 2/-soot conversion was kindly favored. More over nitrite species formed at the catalyst surface might play an important role in NOx-soot conversion. (author)

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

    Energy Technology Data Exchange (ETDEWEB)

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

    1994-12-01

    This report describes research on the oxidative coupling of methane and catalysts involved in coal gasification. Topics include methane pyrolysis and catalysts, and magnetic properties of the coal gasification catalyst Ca-Ni-K-O system.

  3. Tuning size and catalytic activity of nano-clusters of cobalt oxide

    Indian Academy of Sciences (India)

    R Venkat Narayan; Vinod Kanniah; Aruna Dhathathreyan

    2006-03-01

    Cobalt oxides were prepared by three different methods: (1) by reacting cobalt nitrate with oxalic acid, (2) co-precipitating cobalt nitrate with sodium carbonate, and (3) using sodium dodecyl sulphate as organic surfactant. All three samples were characterized before and after calcination by solvent extraction and the resulting products examined by IR spectroscopy. In the case of method 3, the removal of surfactant was followed by TGA studies. Products from all three methods were identified by XRD. Peaks in low angle XRD indicate the porous nature of the oxides. The morphology of the pores was studied by transmission electron microscopy. Some irregular pore structures were obtained for samples from methods 1 and 2, with an average size of 4-6 nm. Only the product from method 3 using SDS as template showed ordered structure and optimum size, and Brunauer-Emmet-Teller surface areas of the as-prepared, as well as the treated samples, exhibited H3 type hysteresis. The samples from the three methods were used as catalysts in the oxidation reaction of cyclohexane under mild conditions and the catalytic efficiency of the cobalt oxide was comparable with mesoporous cobalt oxides.

  4. Catalytic combustion of diesel soot over K2NiF4-type oxides La2-xKxCuO4

    Institute of Scientific and Technical Information of China (English)

    ZHU Ling; WANG Xuezhong; LIANG Cunzhen

    2008-01-01

    Nanostructure K2NiF4 type oxides La2-xKxCuO4 complex oxides were prepared using the Sol-Gel method, characterized by X-Ray Diffraction (XRD), Fourier Transform Infrared (FT-IR), and Scanning Electron Microscopy (SEM). The catalytic activity for soot combustion was evaluated by the Temperature-Programmed Reaction (TPO) technique. The results demonstrated that the substitution quality of K+ for La3+ at the A-site would increase the catalytic activities of La2-xKxCuO4 for soot combustion greatly; the substitution quality affected the structure and catalytic activity obviously. The La1.8K0.2CuO4 complex oxides with tetrahedral structures had the best catalytic activity for soot combustion, and the ignition temperature of soot combustion was lowered from 490 to 320 °C.

  5. Effects of Morphology of Cerium Oxide Catalysts for Reverse Water Gas Shift Reaction

    OpenAIRE

    Kovasevic, M.; Mojet, B.L.; Ommen, van, B.; Lefferts, L.

    2016-01-01

    Reverse water gas shift reaction (RWGS) was investigated over cerium oxide catalysts of distinct morphologies: cubes, rods and particles. Catalysts were characterized by X-ray diffraction, Raman spectroscopy and temperature programmed reduction (TPR) in hydrogen. Nanoshapes with high concentration of oxygen vacancies contain less surface oxygen removable in TPR. Cerium oxide cubes exhibited two times higher activity per surface area as compared to rods and particles. Catalytic activity of the...

  6. Conversion of the refractory ammonia and acetic acid in catalytic wet air oxidation of animal byproducts

    Institute of Scientific and Technical Information of China (English)

    Virginie Fontanier; Sofiane Zalouk; Stéphane Barbati

    2011-01-01

    Wet air oxidation (WAO) and catalytic wet air oxidation (CWAO) of slaughtered animal byproducts (ABPs) were investigated.Two step experiment was carried out consisting ofa non-catalysed WAO run followed by a CWAO run at 170-275℃, 20 MPa, and reaction time 180 min.The WAO (1st step) of sample (5 g/L total organic carbon (TOC)) yielded (82.0 ± 4)% TOC removal and (78.4 ± 13.2)%conversion of the initial organic-N into NH4+-N.Four metal catalysts (Pd, Pt, Rh, Ru) supported over alumina have been tested in catalytic WAO (2nd step) at elevated pH to enhance ammonia conversion and organic matter removal, particularly acetic acid.It was found that the catalysts Ru, Pt, and Rh had significant effects on the TOC removal (95.1%, 99.5% and 96.7%, respectively) and on the abatement of ammonia (93.4%, 96.7% and 96.3%, respectively) with high nitrogen selectivity.The catalyst Pd was found to have the less activity while Pt had the best performance.The X-Ray diffraction analysis showed that the support of catalyst was not stable under the experimental conditions since it reacted with phosphate present in solution.Nitrite and nitrate ions were monitored during the oxidation reaction and it was concluded that CWAO of ammonia in real waste treatment framework was in good agreement with the results obtained from the literature for ideal solutions of ammonia.

  7. Enantiomerically pure bithiophene diphosphine oxides as catalysts for direct double aldol reactions.

    Science.gov (United States)

    Genoni, Andrea; Benaglia, Maurizio; Rossi, Sergio; Celentano, Giuseppe

    2013-10-01

    The direct aldol reaction between aryl methyl ketones with aromatic aldehydes in the presence of tetrachlorosilane and a catalytic amount of a chiral bithiophene diphosphine oxide was studied; the product of double aldol addition was isolated as diacetate in good diastereoselectivity (up to 95:5) and enantioselectivities up to 91%. The reaction with heteroaromatic aldehydes was also investigated leading to the corresponding 1,3 diols, in some cases with excellent stereoselectivities. PMID:23744602

  8. Porous platinum mesoflowers with enhanced activity for methanol oxidation reaction

    International Nuclear Information System (INIS)

    Porous Pt and Pt–Ag alloy mesoflowers (MFs) with about 2 μm in diameter and high porosity were synthesized using Ag mesoflowers as sacrificial template by galvanic reaction. The silver content in Pt–Ag alloys can be facilely controlled by nitric acid treatment. And the pure Pt MFs can be obtained by selective removal of silver element from Pt72Ag28 MFs electrochemically. Both Pt45Ag55, Pt72Ag28 and pure Pt show a high catalytic performance in methanol oxidation reaction (MOR). Especially, pure Pt MFs exhibited a 2 to 3 times current density enhancement in MOR compared with the commercial used Pt black, which can be attributed to their porous nanostructure with 3-dimentional nature and small crystal sizes. - Graphical Abstract: The CVs of MOR on Pt (red) and Pt black (green) catalysts in 0.1 M HClO4 and 0.5 M CH3OH for specific mass current. The insert shows the SEM images of two porous Pt MFs. Platinum mesoflowers (MFs) with about 2 μm in diameter and high porosity were synthesised with Ag mesoflowers as sacrificial template by galvanic replacement. The porous Pt MFs exhibited a more than 3 times enhancement in electrocatalytic performance for methanol oxidation reaction compared the commercial used Pt black. Highlights: ► Porous Pt and Pt–Ag mesoflowers (MFs) were synthesized using Ag MFs sacrifical template. ► Pt MFs presents an improved catalytic activity in MOR compared with Pt black. ► We provided a facile approach for the development of high performance Pt electrocatalysts for fuel cells.

  9. Fabrication of Au–Pd nanoparticles/graphene oxide and their excellent catalytic performance

    Energy Technology Data Exchange (ETDEWEB)

    He, Yongqiang, E-mail: heyongqiang@126.com [Department of Applied Chemistry, Yuncheng University, Yuncheng 044000 (China); Zhang, Nana; Zhang, Lei [School of Science, Tianjin University, Tianjin 300072 (China); Gong, Qiaojuan [Department of Applied Chemistry, Yuncheng University, Yuncheng 044000 (China); Yi, Maocong [School of Science, Tianjin University, Tianjin 300072 (China); Wang, Wei [School of Chemical Engineering, Tianjin University, Tianjin 300072 (China); Qiu, Haixia, E-mail: qhx@tju.edu.cn [School of Science, Tianjin University, Tianjin 300072 (China); Gao, Jianping [School of Science, Tianjin University, Tianjin 300072 (China)

    2014-03-01

    Graphical abstract: - Highlights: • Au and Pd nanoparticles loaded on GO were fabricated without adding any reducing agents. • The Au–Pd NPs/GO were excellent catalysts for the reduction of 4-nitrophenol. • The Au–Pd NPs/GO showed superior catalytic activity for the Suzuki reaction. • The Au–Pd NPs/GO exhibit good reusability. - Abstract: A simple method to fabricate clean Au–Pd nanoparticles on graphene oxide (Au–Pd NPs/GO) without using any reducing agent or surfactant has been developed. GO simultaneously reduced the Au and Pd precursors to form a stable suspension of the Au–Pd NPs/GO. The nanoparticles were characterized by transmission electron microscopy, X-ray diffraction, X-ray photoelectron spectroscopy and inductively coupled plasma. The Au–Pd NPs/GO exhibited catalytic activity for the reduction of 4-nitrophenol to 4-aminophenol and for the Suzuki–Miyaura coupling reaction of chlorobenzene and phenylboronic acid in aqueous media.

  10. Fabrication of Au–Pd nanoparticles/graphene oxide and their excellent catalytic performance

    International Nuclear Information System (INIS)

    Graphical abstract: - Highlights: • Au and Pd nanoparticles loaded on GO were fabricated without adding any reducing agents. • The Au–Pd NPs/GO were excellent catalysts for the reduction of 4-nitrophenol. • The Au–Pd NPs/GO showed superior catalytic activity for the Suzuki reaction. • The Au–Pd NPs/GO exhibit good reusability. - Abstract: A simple method to fabricate clean Au–Pd nanoparticles on graphene oxide (Au–Pd NPs/GO) without using any reducing agent or surfactant has been developed. GO simultaneously reduced the Au and Pd precursors to form a stable suspension of the Au–Pd NPs/GO. The nanoparticles were characterized by transmission electron microscopy, X-ray diffraction, X-ray photoelectron spectroscopy and inductively coupled plasma. The Au–Pd NPs/GO exhibited catalytic activity for the reduction of 4-nitrophenol to 4-aminophenol and for the Suzuki–Miyaura coupling reaction of chlorobenzene and phenylboronic acid in aqueous media

  11. Catalytic pleat filter bags for combined particulate separation and nitrogen oxides removal from flue gas streams

    International Nuclear Information System (INIS)

    The development of a high temperature catalytically active pleated filter bag with hybrid filter equipment for the combined removal of particles and nitrogen oxides from flue gas streams is presented. A special catalyst load in stainless steel mesh cartridge with a high temperature pleated filter bag followed by optimized catalytic activation was developed to reach the required nitrogen oxides levels and to maintain the higher collection efficiencies. The catalytic properties of the developed high temperature filter bags with hybrid filter equipment were studied and demonstrated in a pilot scale test rig and a demonstration plant using commercial scale of high temperature catalytic pleated filter bags. The performance of the catalytic pleated filter bags were tested under different operating conditions, such as filtration velocity and operating temperature. Moreover, the cleaning efficiency and residual pressure drop of the catalyst loaded cartridges in pleated filter bags were tested. As result of theses studies, the optimum operating conditions for the catalytic pleated filter bags are determined. (author)

  12. In situ photoacoustic study of water gas shift reaction over magnetite/chromium oxide and copper/zinc oxide catalysts

    International Nuclear Information System (INIS)

    Kinetic studies on the water-gas shift reaction catalyzed by magnetite/chromium oxide and copper/zinc oxide were carried out by using an in situ photoacoustic spectroscopic technique. The reactions were performed in a closed-circulation reactor system using a differential photoacoustic cell at total pressure of 40 Torr in the temperature range of 100 to 350 .deg. C. The CO2 photoacoustic signal varying with the concentration of CO2 during the catalytic reaction was recorded as a function of time. The time-resolved photoacoustic spectra obtained for the initial reaction stage provided precise data of CO2 formation rate. The apparent activation energies determined from the initial rates were 74.7 kJ/mol for the magnetite/chromium oxide catalyst and 50.9 kJ/mol for the copper/zinc oxide catalyst. To determine the reaction orders, partial pressures of CO(g) and H2O(g) in the reaction mixture were varied at a constant total pressure of 40 Torr with N2 buffer gas. For the magnetite/chromium oxide catalyst, the reaction orders with respect to CO and H2O were determined to be 0.93 and 0.18, respectively. For the copper/zinc oxide catalyst, the reaction orders with respect to CO and H2O were determined to be 0.79 and 0, respectively

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

    Indian Academy of Sciences (India)

    Dhurairajan Senthilnathan; Rajadurai Vijay Solomon; Ponnambalam Venuvanalingam

    2012-01-01

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

  14. Anchoring noble metal nanoparticles on CeO2 modified reduced graphene oxide nanosheets and their enhanced catalytic properties.

    Science.gov (United States)

    Ji, Zhenyuan; Shen, Xiaoping; Xu, Yuling; Zhu, Guoxing; Chen, Kangmin

    2014-10-15

    The strategy of structurally integrating noble metal, metal oxide, and graphene is expected to offer prodigious opportunities toward emerging functions of graphene-based nanocomposites. In this study, we develop a facile two-step approach to disperse noble metal (Pt and Au) nanoparticles on the surface of CeO2 functionalized reduced graphene oxide (RGO) nanosheets. It is shown that Pt and Au with particle sizes of about 5 and 2nm are well dispersed on the surface of RGO/CeO2. The reduction of 4-nitrophenol (4-NP) to 4-aminophenol (4-AP) by NaBH4 was used as a model reaction to quantitatively evaluate the catalytic properties of the as-synthesized RGO/Pt/CeO2 and RGO/Au/CeO2 ternary nanocomposites. In such triple-component catalysts, CeO2 nanocrystals provide unique and critical roles for optimizing the catalytic performance of noble metallic Pt and Au, allowing them to express enhanced catalytic activities in comparison with RGO/Pt and RGO/Au catalysts. In addition, a possible mechanism for the enhanced catalytic activities of the RGO/Pt/CeO2 and RGO/Au/CeO2 ternary catalysts in the reduction of 4-NP is proposed. It is expected that our prepared graphene-based triple-component composites, which inherit peculiar properties of graphene, metal oxide, and noble metal, are attractive candidates for catalysis and other applications. PMID:25080384

  15. Efficient Catalytic Ozonation over Reduced Graphene Oxide for p-Hydroxylbenzoic Acid (PHBA) Destruction: Active Site and Mechanism.

    Science.gov (United States)

    Wang, Yuxian; Xie, Yongbing; Sun, Hongqi; Xiao, Jiadong; Cao, Hongbin; Wang, Shaobin

    2016-04-20

    Nanocarbons have been demonstrated as promising environmentally benign catalysts for advanced oxidation processes (AOPs) upgrading metal-based materials. In this study, reduced graphene oxide (rGO) with a low level of structural defects was synthesized via a scalable method for catalytic ozonation of p-hydroxylbenzoic acid (PHBA). Metal-free rGO materials were found to exhibit a superior activity in activating ozone for catalytic oxidation of organic phenolics. The electron-rich carbonyl groups were identified as the active sites for the catalytic reaction. Electron spin resonance (ESR) and radical competition tests revealed that superoxide radical ((•)O2(-)) and singlet oxygen ((1)O2) were the reactive oxygen species (ROS) for PHBA degradation. The intermediates and the degradation pathways were illustrated from mass spectroscopy. It was interesting to observe that addition of NaCl could enhance both ozonation and catalytic ozonation efficiencies and make ·O2(-) as the dominant ROS. Stability of the catalysts was also evaluated by the successive tests. Loss of specific surface area and changes in the surface chemistry were suggested to be responsible for catalyst deactivation. PMID:27007603

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

    International Nuclear Information System (INIS)

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

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

    Science.gov (United States)

    López-Cueto, G; Casado-Riobó, J A

    1979-02-01

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

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

    Czech Academy of Sciences Publication Activity Database

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

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

  19. Investigation of catalytic reactions in novel ionic liquids

    OpenAIRE

    Dai, Jifeng

    2003-01-01

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

  20. Catalytic wet-air oxidation of lignin in a three-phase reactor with aromatic aldehyde production

    OpenAIRE

    Sales F.G.; Abreu C.A.M.; Pereira J. A. F. R.

    2004-01-01

    In the present work a process of catalytic wet air oxidation of lignin obtained from sugar-cane bagasse is developed with the objective of producing vanillin, syringaldehyde and p-hydroxybenzaldehyde in a continuous regime. Palladium supported on g-alumina was used as the catalyst. The reactions in the lignin degradation and aldehyde production were described by a kinetic model as a system of complex parallel and series reactions, in which pseudo-first-order steps are found. For the purpose o...

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

    OpenAIRE

    Кириченко, Алексей Геннадьевич; Колесник, Дмитрий Николаевич

    2011-01-01

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

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

    Science.gov (United States)

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

    2016-07-01

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

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

    NARCIS (Netherlands)

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

    2009-01-01

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

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

    NARCIS (Netherlands)

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

    2009-01-01

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

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

    NARCIS (Netherlands)

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

    2004-01-01

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

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2004-07-01

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

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

    Institute of Scientific and Technical Information of China (English)

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

    2009-01-01

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

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

    Science.gov (United States)

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

    2015-05-28

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

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

    OpenAIRE

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

    2009-01-01

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

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

    Institute of Scientific and Technical Information of China (English)

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

    2005-01-01

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

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

    OpenAIRE

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

    2015-01-01

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

  12. Catalytic oxidation of 2-aminophenols and ortho hydroxylation of aromatic amines by tyrosinase

    International Nuclear Information System (INIS)

    The usual substrates of tyrosinase, a copper-containing monooxygenase (EC 1.14.18.1), are monophenols and o-diphenols which are both converted to o-quinones. In this paper, the authors studied the reaction of this enzyme with two new classes of substrates: aromatic amines and o-aminophenols, structural analogues of monophenols and o-diphenols, respectively. They undergo the same catalytic reactions (ortho hydroxylation and oxidation), as documented by product analysis and kinetic studies. In the presence of tyrosinase, arylamines and o-aminophenols are converted to o-quinone imines, which are isolated as quinone anils or phenoxazones. As an example, in the presence of tyrosinase, 2-amino-3-hydroxybenzoic acid (an o-aminophenol) is converted to cinnabarinic acid, a well-known phenoxazone, while p-aminotoluene (an aromatic amine) gives rise to the formation of 5-amino-2-methyl-1,4-benzoquinone 1-(4-methylanil). Kinetic studies using an oxygen electrode show that arylamines and the corresponding monophenols exhibit similar Michaelis constants. In contrast, the reaction rates observed for aromatic amines are relatively slow as compared to monophenols. The enzymatic conversion of arylamines by tryosinase is different from the typical ones: N-oxidation and ring hydroxylation without further oxidation. This difference originates from the regiospecific hydroxylation (ortho position) and subsequent oxidation of the intermediate o-aminophenol to the corresponding o-quinone imine. Finally, the well-know monooxygenase activity of tyrosinase was also confirmed for the aromatic amine p-aminotoluene, with 18O2

  13. Quantitative Aspects of the Interfacial Catalytic Oxidation of Dithiothreitol by Dissolved Oxygen in the Presence of Carbon Nanoparticles.

    Science.gov (United States)

    Sauvain, Jean-Jacques; Rossi, Michel J

    2016-01-19

    The catalytic nature of particulate matter is often advocated to explain its ability to generate reactive oxygen species, but quantitative data are lacking. We have performed molecular characterization of three different carbonaceous nanoparticles (NP) by 1. identifying and quantifying their surface functional groups based on probe gas-particle titration; 2. studying the kinetics of dissolved oxygen consumption in the presence of suspended NP's and dithiothreitol (DTT). We show that these NP's can reversibly change their oxidation state between oxidized and reduced functional groups present on the NP surface. By comparing the amount of O2 consumed and the number of strongly reducing sites on the NP, its average turnover ranged from 35 to 600 depending on the type of NP. The observed quadratic rate law for O2 disappearance points to a Langmuir-Hinshelwood surface-based reaction mechanism possibly involving semiquinone radical. In the proposed model, the strongly reducing surface site is assumed to be a polycyclic aromatic hydroquinone whose oxidation to the corresponding conjugated quinone is rate-limiting in the catalytic chain reaction. The presence and strength of the reducing surface functional groups are important for explaining the catalytic activity of NP in the presence of oxygen and a reducing agent like DTT. PMID:26683500

  14. Microreactor for the Catalytic Partial Oxidation of Methane

    Institute of Scientific and Technical Information of China (English)

    Widodo Wahyu Puwanto; Yuswan Muharam

    2006-01-01

    Fixed-bed reactors for the partial oxidation of methane to produce synthetic gas still pose hotspot problems. An alternative reactor, which is known as the shell-and-tube-typed microreactor, has been developed to resolve these problems. The microreactor consists of a 1 cm outside-diameter, 0.8 cm insidediameter and 11 cm length tube, and a 1.8 cm inside-diameter shell. The tube is made of dense alumina and the shell is made of quartz. Two different methods dip and spray coating were performed to line the tube side with the LaNixOy catalyst. Combustion and reforming reactions take place simultaneously in this reactor. Methane is oxidized in the tube side to produce flue gases (CO2 and H2O) which flow counter-currently and react with the remaining methane in the shell side to yield synthesis gas. The methane conversion using the higher-loading catalyst spray-coated tube reaches 97% at 700 ℃, whereas that using the lower-loading catalyst dip-coated tube reaches only 7.78% because of poor adhesion between the catalyst film and the alumina support. The turnover frequencies (TOFs) using the catalyst spray-and 900 ℃ provides better performance than that at 1250 ℃ because sintering reduces the surface-area. The hydrogen to carbon monoxide ratio produced by the spray-coated catalyst is greater than the stoichiometric ratio, which is caused by carbon deposition through methane cracking or the Boudouard reaction.

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

    Science.gov (United States)

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

    2014-06-01

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

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2014-06-01

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

  17. Elucidating molecular iridium water oxidation catalysts using metal-organic frameworks: a comprehensive structural, catalytic, spectroscopic, and kinetic study.

    Science.gov (United States)

    Wang, Cheng; Wang, Jin-Liang; Lin, Wenbin

    2012-12-01

    As a new class of porous, crystalline, molecular materials, metal-organic frameworks (MOFs) have shown great promise as recyclable and reusable single-site solid catalysts. Periodic order and site isolation of the catalytic struts in MOFs facilitate the studies of their activities and reaction mechanisms. Herein we report the construction of two highly stable MOFs (1 and 2) using elongated dicarboxylate bridging ligands derived from Cp*Ir(L)Cl complexes (L = dibenzoate-substituted 2,2'-bipyridine, bpy-dc, or dibenzoate-substituted 2-phenylpyridine, ppy-dc) and Zr(6)O(4)(OH)(4)(carboxylate)(12) cuboctahedral secondary building units (SBUs) and the elucidation of water oxidation pathways of the Cp*Ir(L)Cl catalysts using these MOFs. We carried out detailed kinetic studies of Ce(4+)-driven water oxidation reactions (WORs) catalyzed by the MOFs using UV-vis spectroscopy, phosphorescent oxygen detection, and gas chromatographic analysis. These results confirmed not only water oxidation activity of the MOFs but also indicated oxidative degradation of the Cp* rings during the WOR. The (bpy-dc)Ir(H(2)O)(2)XCl (X is likely a formate or acetate group) complex resulted from the oxidative degradation process was identified as a competent catalyst responsible for the water oxidation activity of 1. Further characterization of the MOFs recovered from WORs using X-ray photoelectron, diffuse-reflectance UV-vis absorption, luminescence, and infrared spectroscopies supported the identity of (bpy-dc)Ir(H(2)O)(2)XCl as an active water oxidation catalyst. Kinetics of MOF-catalyzed WORs were monitored by Ce(4+) consumptions and fitted with a reaction-diffusion model, revealing an intricate relationship between reaction and diffusion rates. Our work underscores the opportunity in using MOFs as well-defined single-site solid catalytic systems to reveal mechanistic details that are difficult to obtain for their homogeneous counterparts. PMID:23136923

  18. Application of Moessbauer Spectroscopy to the Carbon Oxides Hydrogenation Reactions

    International Nuclear Information System (INIS)

    Iron-based catalysts have favorable activity and selectivity properties for the CO and CO2 hydrogenation reactions. Several Fe phases (oxides and carbides) can be present in these catalysts. The interaction of Fe with the other components of the catalyst (support, promoters) can affect the ease of reduction and also its transformation during the reactions. In this work, the relationship between catalytic behavior in the CO and CO2 hydrogenation reactions and the Fe phase composition of fresh and reacted catalysts was studied. Two types of catalysts were tested: a laterite and the other one made of iron supported on alumina, both unpromoted and promoted with K and Mn. Only those Fe species which can be reduced-carburized, by means of a pretreatment or by an in situ transformation under the reaction, seem to be able to perform the CO or CO2 hydrogenation. The reoxidation of the Fe carbide to magnetite was not associated to deactivation. The selectivity seems to be more affected by Fe species difficult to reduce than by magnetite produced by reoxidation

  19. Investigation of the ignition behaviour of the noble metal catalyzed catalytic partial oxidation of methane

    International Nuclear Information System (INIS)

    Catalytic partial oxidation (CPO) of methane to hydrogen and carbon monoxide over Pt-Rh/Al2O3 and Pt/Al2O3 was studied in-situ with a new QEXAFS setup. The structural changes of the catalysts were investigated on the subsecond timescale during two reaction steps by recording both XANES and full EXAFS spectra: (1) heating and ignition in 6%CH4/3%O2/He, (2) periodic changes between the reaction gas mixture and H2 atmosphere. The results showed that the ignition occurred at lower temperatures for Pt-Rh/Al2O3 while it was completed in a significant shorter time interval for Pt/Al2O3. Some structural changes during the heating phase were detectable before the reaction ignited, especially for Pt/Al2O3, as reflected by the performed principle component analysis. However, a closer analysis of the FT-QEXAFS data did not evidence a defined intermediate. In addition, the composition of the gas atmosphere was altered between hydrogen and the reaction mixture, enabling modulation excitation spectroscopy. This technique was for the first time applied to QEXAFS data and resulted in significantly enhanced data quality.

  20. Preparation, characterization and catalytic performance of Mo-V-O oxide layers linked by alkylamines.

    Science.gov (United States)

    Wang, Feng; Ueda, Wataru

    2009-03-01

    Thin layers of alkylamine-stabilized molybdenum vanadium complex oxide were prepared under hydrothermal condition; these materials exhibited 10-60 times higher catalytic activities than pure crystalline Mo-V-O oxide in the selective oxidation of alcohols. PMID:19225642

  1. Influence of size-induced oxidation state of platinum nanoparticles on selectivity and activity in catalytic methanol oxidation in the gas phase.

    Science.gov (United States)

    Wang, Hailiang; Wang, Yihai; Zhu, Zhongwei; Sapi, Andras; An, Kwangjin; Kennedy, Griffin; Michalak, William D; Somorjai, Gabor A

    2013-06-12

    Pt nanoparticles with various sizes of 1, 2, 4, and 6 nm were synthesized and studied as catalysts for gas-phase methanol oxidation reaction toward formaldehyde and carbon dioxide under ambient pressure (10 Torr of methanol, 50 Torr of oxygen, and 710 Torr of helium) at a low temperature of 60 °C. While the 2, 4, and 6 nm nanoparticles exhibited similar catalytic activity and selectivity, the 1 nm nanoparticles showed a significantly higher selectivity toward partial oxidation of methanol to formaldehyde, but a lower total turnover frequency. The observed size effect in catalysis was correlated to the size-dependent structure and oxidation state of the Pt nanoparticles. X-ray photoelectron spectroscopy and infrared vibrational spectroscopy using adsorbed CO as molecular probes revealed that the 1 nm nanoparticles were predominantly oxidized while the 2, 4, and 6 nm nanoparticles were largely metallic. Transmission electron microscopy imaging witnessed the transition from crystalline to quasicrystalline structure as the size of the Pt nanoparticles was reduced to 1 nm. The results highlighted the important impact of size-induced oxidation state of Pt nanoparticles on catalytic selectivity as well as activity in gas-phase methanol oxidation reactions. PMID:23701488

  2. Size Effect of Gold Sol/γ-Alumina on the Catalytic Activities of CO Oxidation

    Institute of Scientific and Technical Information of China (English)

    WANG Wei-Hua; GAO Geng-Yu

    2006-01-01

    The relationship between particle size and catalytic activity of gold nanoparticle catalysts with γ-Al2O3 as support has been investigated. The catalysts were prepared via the gold sol with different particle sizes by micelle method, and their structures were characterized by HRTEM and XRD, respectively. Furthermore, the catalytic activities were tested by CO oxidation. Experimental results showed that the catalytic activity became much weaker when gold particles were increased from 3.2 to 6.6 nm. Additionally, the particle size was also a key factor to govern catalytic activity with regard to gold supported on TiO2 prepared by the methods of deposition-precipitation.

  3. CATALYTIC WET AIR OXIDATION OF INDUSTRIAL EFFLUENTS USING A Pt CATALIST SUPPORTED ON MULTIWALLED CARBON NANOTUBES

    OpenAIRE

    Gabriel Ovejero; José L. Sotelo; Araceli Rodríguez; Ana Vallet; Juan García

    2011-01-01

    In this work, catalytic wet air oxidation in a batch reactor was studied by catalytic wet air oxidation to treat industrial wastewater. Basic Yellow 11, a basic dye, was employed as a model compound and platinum supported over multi-walled nanotubes (Pt/MWNT) was used as catalyst. Additionally, two different industrial wastewaters were tested. The results prove the high effectivity of this treatment, showing high extents of total organic carbon and toxicity removal of the final effluent. We c...

  4. Effects of Gas Velocity and Temperature on Nitric Oxide Conversion in Simulated Catalytic Converter

    OpenAIRE

    Sathaporn Chuepeng

    2012-01-01

    Problem statement: Gaseous emissions from gasoline engine such as carbon monoxide, unburned hydrocarbon and nitrogen oxides were usually reduced in three-way catalytic converter simultaneously around theoretical fuel and air combustion. Engine speed and load and other parameters were varied over a wide range of operating conditions, resulting in different exhaust gas composition and condition intake into catalytic converter. This work was studied the conversion of Nitric Oxide (NO) in exhaust...

  5. Overcoming the "oxidant problem": strategies to use O2 as the oxidant in organometallic C-H oxidation reactions catalyzed by Pd (and Cu).

    Science.gov (United States)

    Campbell, Alison N; Stahl, Shannon S

    2012-06-19

    Oxidation reactions are key transformations in organic chemistry because they can increase chemical complexity and incorporate heteroatom substituents into carbon-based molecules. This principle is manifested in the conversion of petrochemical feedstocks into commodity chemicals and in the synthesis of fine chemicals, pharmaceuticals, and other complex organic molecules. The utility and function of these molecules correlate directly with the presence and specific placement of oxygen and nitrogen heteroatoms and other functional groups within the molecules. Methods for selective oxidation of C-H bonds have expanded significantly over the past decade, and their role in the synthesis of organic chemicals will continue to increase. Our group's contributions to this field are linked to our broader interest in the development and mechanistic understanding of aerobic oxidation reactions. Molecular oxygen (O(2)) is the ideal oxidant. Its low cost and lack of toxic byproducts make it a highly appealing reagent that can address key "green chemistry" priorities in industry. With strong economic and environmental incentives to use O(2), the commmodity chemicals industry often uses aerobic oxidation reactions. In contrast, O(2) is seldom used to prepare more-complex smaller-volume chemicals, a limitation that reflects, in part, the limited synthetic scope and utility of existing aerobic reactions. Pd-catalyzed reactions represent some of the most versatile methods for selective C-H oxidation, but they often require stoichiometric transition-metal or organic oxidants, such as Cu(II), Ag(I), or benzoquinone. This Account describes recent strategies that we have identified to use O(2) as the oxidant in these reactions. In Pd-catalyzed C-H oxidation reactions that form carbon-heteroatom bonds, the stoichiometric oxidant is often needed to promote difficult reductive elimination steps in the catalytic mechanism. To address this challenge, we have identified new ancillary ligands for

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

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

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

  7. The effect of microstructural properties of CoCr2O4 spinel oxides on catalytic combustion of dichloromethane

    Science.gov (United States)

    Liu, Jing-Di; Zhang, Ting-Ting; Jia, Ai-Pin; Luo, Meng-Fei; Lu, Ji-Qing

    2016-04-01

    It was found that a series of spinel CoCr2O4 oxides were very active and selective for dichloromethane combustion, and the best performance was obtained on a catalyst calcined at 600 °C (with a areal specific reaction rate of 3.41 × 10-8 molCH2Cl2 s-1 m-2 at 220 °C). Quantitative analyses revealed that Cr3+/Cr6+ cations could partially substitute Co3+ cations in the octahedral sites of the spinel oxide at high-temperature calcination and thus to enhanced reducibility and surface acidity of the oxide, which synergistically governed the observed catalytic behaviors. Moreover, it was found that high valent Cr species (Cr6+) played very important role in the reaction, with a much higher turnover frequency (2.2 × 10-3 s-1) than that of the Cr3+ (0.56 × 10-3 s-1).

  8. Iridium ultrasmall nanoparticles, worm-like chain nanowires, and porous nanodendrites: One-pot solvothermal synthesis and catalytic CO oxidation activity

    Science.gov (United States)

    Zhang, Tao; Li, Shuai-Chen; Zhu, Wei; Ke, Jun; Yu, Jing-Wen; Zhang, Zhi-Ping; Dai, Lin-Xiu; Gu, Jun; Zhang, Ya-Wen

    2016-06-01

    We report a facile one-pot solvothermal synthesis of monodisperse iridium (Ir) ultrasmall (1.5-2.5 nm in diameter) nanoparticles (NPs), worm-like chain nanowires (NWs), and porous nanodendrites (NDs), for which CO oxidation reaction has been employed as a probe reaction to investigate the effects of nanoparticle size and surface-capping organics on the catalytic activities. Time-dependent experiments revealed that an oriented attachment mechanism induced by the strong adsorption of halide anions (Br- and I-) on specific facet of Ir nanoclusters or by decreasing the reduction rate of Ir precursors with changing their concentrations during the synthesis was responsible for the formation of Ir NWs and NDs. Annealing tests indicated that an O2-H2 atmosphere treatment turned out to be an effective measure to clean up the surface-capping organics of Ir NPs supported on commercial SiO2. Catalytic CO oxidation reaction illustrated that a significant improvement in the catalytic activity of CO oxidation reaction was achieved together with the changing of activation energies after such atmosphere treatment for the supported catalysts of the ultrasmall Ir NPs. It is noteworthy that this enhancement in catalytic activity could be ascribed to the changes in the surface status (including populations of Ir species in metallic and oxidized states, removal of surface capping organics, the variety of active sites, and total effective active site number) for the supported nanocatalysts during the atmosphere treatment.

  9. A non-chemically selective top-down approach towards the preparation of hierarchical TS-1 zeolites with improved oxidative desulfurization catalytic performance.

    Science.gov (United States)

    Du, Shuting; Chen, Xiaoxin; Sun, Qiming; Wang, Ning; Jia, Mingjun; Valtchev, Valentin; Yu, Jihong

    2016-02-28

    Hierarchical TS-1 zeolites with secondary macropores have been successfully prepared by using two different fluoride-containing chemical etching post-treated routes. Hierarchical TS-1 zeolites exhibited a chemical composition similar to that of the parent material and showed remarkably enhanced catalytic activity in oxidative desulfurization reaction. PMID:26846586

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

    Institute of Scientific and Technical Information of China (English)

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

    2015-01-01

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

  11. Effects of carrier and Mn loading on supported manganese oxide catalysts for catalytic combustion of methane

    Institute of Scientific and Technical Information of China (English)

    Jinyan Hu; Wei Chu; Limin Shi

    2008-01-01

    Supported manganese oxide catalysts were prepared by incipient wetness impregnation method for methane cat-alytic combustion, and effects of the support (Al2O3, SiO2 and TiO2) and Mn loading were investigated. These catalysts were characterized with N2 adsorption, X-ray diffraction, X-ray photoelectron spectroscopy and temperature-programmed reduction techniques. Methane conversion varied in a large range depending on supports or Mn loading. Al2O3 supported 15% Mn cata-lyst exhibited better activity toward methane catalytic oxidation. The manganese state and oxygen species played an important role in the catalytic performance.

  12. UV-Shielding and Catalytic Characteristics of Nanoscale Zinc-Cerium Oxides

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    Fine particles of zinc-cerium oxides (ZCO) used as an ultraviolet filter were prepared via combustion synthesis route. The catalytic activity, UV-shielding performance, surface modification and application of ZCO in polyester varnish were discussed in detail. The experimental results indicate that the photo-catalytic activity of ZCO is much smaller than these of ZnO and TiO2; the oxidation catalytic activity of ZCO is far lower than that of CeO2; the ZCO has shown excellent ultraviolet absorption in the range of UV;addition modified ZCO (MZCO) into polyester will enhance the UV-shielding capability of polyester.

  13. Superior Fe-ZSM-5 catalyst for selective catalytic reduction of nitric oxide by ammonia

    Energy Technology Data Exchange (ETDEWEB)

    Long, R.Q.; Yang, R.T. [Univ. of Michigan, Ann Arbor, MI (United States). Dept. of Chemical Engineering

    1999-06-16

    Nitrogen oxides in the exhaust gases from combustion of fossil fuels remain a major source for air pollution and acid rain. The current technology for reducing NO{sub x} (NO + NO{sub 2}) emissions from power plants is selective catalytic reduction (SCR) with ammonia in the presence of oxygen. For the SCR reaction, V{sub 2}O{sub 5} + WO{sub 3} (or MoO{sub 3}) supported on TiO{sub 2} are the commercial catalysts. The mechanism of the reaction on the vanadia catalysts has been studied extensively, and several different mechanisms have been proposed. Ion-exchanged zeolite catalysts have also been studied, e.g., Fe-Y, Cu-ZSM-5, and Fe-ZSM-5, but the reported activities were lower than that of the commercial vanadia catalysts. The SCR technology based on vanadia catalysts is being used in Europe and Japan and is being quickly adopted in the US. However, problems associated with vanadia catalysts remain, e.g., high activity for oxidation of SO{sub 2} to SO{sub 3}, toxicity of vanadia, and formation of N{sub 2}O at high temperature. Hence, there are continuing efforts in developing new catalysts. In this paper, the authors report a superior Fe-ZSM-5 catalyst that is much more active than the commercial vanadia catalysts and does not have the deficiencies that are associated with the vanadia catalysts.

  14. Catalytic incineration of CO and VOC emissions over supported metal oxide catalysts

    Energy Technology Data Exchange (ETDEWEB)

    Larsson, Per-Olof

    1999-05-01

    can be due to an epitaxial relationship during reaction conditions, or that the CeO{sub 2}(001) surface has a greater ability, compared with the CeO{sub 2}(111) surface, to assist the copper oxide in changing valences and supplying oxygen to the CO. A CuO{sub x}-CeO{sub 2}/Al{sub 2}O{sub 3} catalyst was more active than a CuMn{sub 2}O{sub 4}/Al{sub 2}O{sub 3} catalyst for CO oxidation, but the CuMn{sub 2}O{sub 4}/Al{sub 2}O{sub 3} catalyst was more active for combustion of ethyl acetate and ethanol. This shows that the activity order for complete oxidation over different metal oxide catalysts depends on the combustible component. In addition, these metal oxide catalysts were found to be more active than a Pt/Al{sub 2}O{sub 3} catalyst for the combustion of ethyl acetate and ethanol. However, for methanol and formaldehyde combustion the Pt/Al{sub 2}O{sub 3} catalyst was the best alternative. Consequently, catalytic waste gas incineration can be more efficient by using the right type of catalyst in each application. By-products as acetaldehyde and acetic acid were observed during catalytic combustion of an ethyl acetate/ethanol mixture. However, in stationary catalytic incineration it is easy to secure complete oxidation to CO{sub 2} and H{sub 2}O 61 refs, 29 figs, 4 tabs

  15. Synthesis and catalytic properties of microemulsion-derived cerium oxide nanoparticles

    Science.gov (United States)

    Kockrick, Emanuel; Schrage, Christian; Grigas, Anett; Geiger, Dorin; Kaskel, Stefan

    2008-07-01

    The synthesis of cerium dioxide nanoparticles using an inverse microemulsion technique and precipitation method was investigated. Cerium hydroxide nanoparticles were synthesized by adding diluted ammonia to n-heptane-surfactant-cerium nitrate system. The micelle and particle size in the range of 5-12 nm were controlled by varying the molar water to surfactant ratio and analyzed by dynamic light scattering (DLS), small angle X-ray scattering (SAXS) and high-resolution transmission electron microscopy (HRTEM). Cerium hydroxide nanoparticles were isolated and subsequently treated at 100-600 °C to obtain nanoscale ceria. Crystallite sizes of cerium dioxide in the range of 6-16 nm were estimated by Scherrer analysis by X-ray diffraction (XRD) and HRTEM. The catalytic activity of particles annealed at 400 and 600 °C in soot combustion reactions was characterized by temperature-programmed oxidation (TPO) indicating a size-dependant activity. Crystallite sizes and catalytic stability of elevated ceria systems were tested in second combustion cycles.

  16. Thermal catalytic oxidation of octachloronaphthalene over anatase TiO2 nanomaterial and its hypothesized mechanism

    Science.gov (United States)

    Su, Guijin; Li, Qianqian; Lu, Huijie; Zhang, Lixia; Huang, Linyan; Yan, Li; Zheng, Minghui

    2015-12-01

    As an environmentally-green technology, thermal catalytic oxidation of octachloronaphthalene (CN-75) over anatase TiO2 nanomaterials was investigated at 300 °C. A wide range of oxidation intermediates, which were investigated using various techniques, could be of three types: naphthalene-ring, single-benzene-ring, and completely ring-opened products. Reactive oxygen species on anatase TiO2 surface, such as O2-• and O2-, contributed to oxidative degradation. Based on these findings, a novel oxidation degradation mechanism was proposed. The reaction at (101) surface of anatase TiO2 was used as a model. The naphthalene-ring oxidative products with chloronaphthols and hydroxyl-pentachloronaphthalene-dione, could be formed via attacking the carbon of naphthalene ring at one or more positions by nucleophilic O2-. Lateral cleavage of the naphthalene ring at different C1-C10 and C4-C9, C1-C2 and C4-C9, C1-C2 or and C3-C4 bond positions by electrophilic O2-• could occur. This will lead to the formation of tetrachlorophenol, tetrachloro-benzoic acid, tetrachloro-phthalaldehyde, and tetrachloro-acrolein-benzoic acid, partially with further transformation into tetrachlorobenzene-dihydrodiol and tetrachloro-salicylic acid. Unexpectedly, the symmetric half section of CN-75 could be completely remained with generating the intricate oxidative intermediates characteristically containing tetrachlorobenzene structure. Complete cleavage of naphthalene ring could produce the ring-opened products, such as formic and acetic acids.

  17. Bio-inspired immobilization of metal oxides on monolithic microreactor for continuous Knoevenagel reaction.

    Science.gov (United States)

    Song, Wentong; Shi, Da; Tao, Shengyang; Li, Zhaoliang; Wang, Yuchao; Yu, Yongxian; Qiu, Jieshan; Ji, Min; Wang, Xinkui

    2016-11-01

    A facile method is reported to construct monolithic microreactor with high catalytic performance for Knoevenagel reaction. The microreactor is based on hierarchically porous silica (HPS) which has interconnected macro- and mesopores. Then the HPS is surface modified by pyrogallol (PG) polymer. Al(NO3)3 and Mg(NO3)2 are loaded on the surface of HPS through coordination with -OH groups of PG. After thermal treatment, Al(NO3)3 and Mg(NO3)2 are converted Al2O3 and MgO. The as-synthesized catalytic microreactor shows a high and stable performance in Knoevenagel reaction. The microreactor possess large surface area and interconnected pore structures which are beneficial for reactions. Moreover, this economic, facile and eco-friendly surface modification method can be used in loading more metal oxides for more reactions. PMID:27459172

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

    Science.gov (United States)

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

    2015-07-01

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

  19. Pretreatment of apramycin wastewater by catalytic wet air oxidation

    Institute of Scientific and Technical Information of China (English)

    YANG Shao-xia; FENG Yu-jie; WAN Jia-feng; LIN Qing-ying; ZHU Wan-peng; JIANG Zhan-peng

    2005-01-01

    The pretreatment technology of wet air oxidation(WAO) and coagulation and acidic hydrolysis for apramycin wastewater was investigated in this paper. The COD, apramycin, NH4+ concentration, and the ratio of BOD5/COD were analyzed, and the color and odor of the effluent were observed. WAO of apramycin wastewater, without catalyst and with RuO2/Al2 O3 and RuO2-CeO2/Al2 O3 catalysts, was carried out at degradation temperature of 200℃ and the total pressure of 4 MPa in a 1 L batch reactor. The result showed that the apramycin removals were respectively 50.2% and 55.0%, COD removals were 40.0% and 46.0%, and the ratio of BOD5/COD was increased to 0.49 and 0.54 with RuO2/Al2 O3 and RuO2-CeO2/Al2 O3 catalysts in catylytic wet air oxidation(CWAO) after the reaction of 150 min. With the pretreatment of coagulation and acidic hydrolysis, COD and apramycin removals were slight decreased, and the ratio of BOD5/COD was increased to 0.45, and the effluents was not suitable to biological treatment. The color and odor of the wastewater were the apramycin wastewater. The addition of CeO2 could promote the activity and stability of RuO2/Al2 O3 in WAO of apramycin wastewater.

  20. Contribution to the study of the oxidation reaction of the carbon oxide in contact with catalysts issued from the decomposition of nickel hydro-aluminates at various temperatures

    International Nuclear Information System (INIS)

    Addressing the study of the oxidation reaction of carbon oxide which produces carbon dioxide, this research thesis reports the study of this reaction in presence of catalysts (2NiO + Al2O3, NiAl2O4 and NiO + NiAl2O4) issued from the decomposition of nickel hydro-aluminates at different temperatures. The first part describes experimental techniques and the nature of materials used in this study. The second part reports the study of the catalytic activity of the 2NiO+Al2O3 catalyst during the oxidation of CO. Preliminary studies are also reported: structure and texture of nickel hydro-aluminate which is the raw material used to produce catalysts, activation of this compound to develop the catalytic activity in CO oxidation, chemisorption of CO, O2 and CO2 on the 2NiO+Al2O3 solid, interaction of adsorbed gases at the solid surface, and kinetic study of the oxidation reaction. The third part reports the study of the catalytic activity in the oxidation reaction of CO of spinel catalysts (NiAl2O4 and NiO+NiAl2O4) obtained by calcination of nickel hydro-aluminates at high temperature. The formation of the spinel phase, the chemisorption of CO, O2 and CO2 on NiAl2O4, and the kinetic of the oxidation reaction are herein studied

  1. Catalytic oxidation of xanthine by the nanostructured poly(aniline-co-2,4-diaminophenol)

    International Nuclear Information System (INIS)

    Poly(aniline-co-2,4-diaminophenol) (PADAP) was synthesized in a solution containing aniline, 2,4-diaminophenol (DAP) and sulfuric acid, using potentiostatic method. The image of a PADAP film is constructed of spherical particles with an average diameter of 50 nm, which was examined by both scanning electron microscope (SEM) and atomic force microscopy (AFM). The nanostructured PADAP can catalyze xanthine oxidation under a less positive potential of 0.31 V (vs. SCE), which was proved by cyclic voltammetry and amperometric method. The PADAP electrode has a very fast response for the determination of xanthine. The response current of the PADAP electrode increases with increasing xanthine concentration and applied potential. The catalytic mechanism for the oxidation of xanthine on the nanostructured PADAP electrode is similar to that of xanthine oxidase-catalyzed reaction. Experimental evidence for the electrocatalytic mechanism of xanthine oxidation on a PADAP electrode was demonstrated via measurements of the open-circuit potential and the in situ chemical-ESR spectra of PADAP in the solutions without and with xanthine, respectively.

  2. Selective Production of Aromatic Aldehydes from Heavy Fraction of Bio-oil via Catalytic Oxidation

    International Nuclear Information System (INIS)

    High value-added aromatic aldehydes (e. g. vanillin and syringaldehyde) were produced from heavy fraction of bio-oil (HFBO) via catalytic oxidation. The concept is based on the use of metalloporphyin as catalyst and hydrogen peroxide (H2O2) as oxidant under alkaline condition. The biomimetic catalyst cobalt(II)-sulfonated tetraphenylporphyrin (Co(TPPS4)) was prepared and characterized. It exhibited relative high activity in the catalytic oxidation of HFBO. 4.57 wt % vanillin and 1.58 wt % syringaldehyde were obtained from catalytic oxidation of HFBO, compared to 2.6 wt % vanillin and 0.86 wt % syringaldehyde without Co(TPPS4). Moreover, a possible mechanism of HFBO oxidation using Co(TPPS4)/H2O2 was proposed by the research of model compounds. The results showed that this is a promising and environmentally friendly method for production of aromatic aldehydes from HFBO under Co(TPPS4)/H2O2 system

  3. In situ infrared (FTIR) study of the borohydride oxidation reaction

    Energy Technology Data Exchange (ETDEWEB)

    Concha, B. Molina; Chatenet, M. [Laboratoire d' Electrochimie et de Physico-chimie, des Materiaux et des Interfaces (LEPMI), UMR 5631 CNRS/Grenoble-INP/UJF, 1130 Rue de la Piscine, BP75, 38402 Saint Martin d' Heres Cedex (France); Coutanceau, C.; Hahn, F. [Laboratoire de Catalyse en Chimie Organique (LACCO), UMR 6503 CNRS, Universite de Poitiers, 40 Av. du, Recteur Pineau, 86000 Poitiers (France)

    2009-01-15

    The direct borohydride fuel cell (DBFC) is an interesting alternative for the electrochemical power generation at lower temperatures due to its high anode theoretical specific capacity (5 A h g{sup -1}). However, the borohydride oxidation reaction (BOR) is a very complex eight-electron reaction, influenced by the nature of the electrode material (catalytic or not with respect to BH{sub 4}{sup -} hydrolysis), the [BH{sub 4}{sup -}][OH{sup -}] ratio and the temperature. In order to understand the BOR mechanism, we performed in situ infrared reflectance spectroscopy measurements (SPAIRS technique) in 1 M NaOH/1 M NaBH{sub 4} with the aim to study intermediate reactions occurring on a gold electrode (a poor BH{sub 4}{sup -} hydrolysis catalyst). We monitored several bands in B-H (1184 cm{sup -1}) and B-O bond regions (1326 and 1415 cm{sup -1}), appearing sequentially with increasing electrode polarisation. Thanks to these experimental findings, we propose possible initial elementary steps for the BOR. (author)

  4. The effect of outside conditions on anaerobic ammonia oxidation reaction

    Institute of Scientific and Technical Information of China (English)

    YANG Min; WANG Shu-bo

    2016-01-01

    Organic carbon, inorganic carbon, temperature, pH and ORP are all to have a certain influence on the anaerobic ammonia oxidation reaction. We can draw some conclusions on the optimum conditions of anaerobic ammonia oxidation reaction. The optimum temperature of the anaerobic ammonia oxidation reaction is 30-35℃. And the optimum pH of the anaerobic ammonia reaction is 7.5-8.3. The presence of organic matters can affect the anaerobic ammonia reaction, and different organic matters have different influence on it. The concentration of the inorganic carbon also exist great influence on the reaction. High inorganic carbon concentration also can inhibit anaerobic ammonia oxidation reaction.

  5. Redox transformations in the surface layer of complex RBa2Cu3Oy oxides (R = Nd, Ho, Y) and their catalytic properties in CO oxidation

    International Nuclear Information System (INIS)

    Initial stages of redox transformations in the surface layer of complex oxides with the RBa2Cu3Oy (R = Nd, Ho, Y) composition at their reaction with CO and O2 in non-stationary conditions were studied using pulse microcatalytic method. It is demonstrated that weak-connected oxygen is removed, surface layer produced by reduction of RBa2Cu3Oy is formed during interaction of RBa2Cu3Oy (R = Nd, Ho, Y) phases with CO. RBa2Cu3Oy oxides established to be possess of ability to reoxidation following reduction treatment. Principal capability of multicomponent RBa2Cu3Oy volume phase oxygen participation in reaction of catalytic oxidation of CO was shown

  6. Magnetic carbon xerogels for the catalytic wet peroxide oxidation of 4-nitrophenol solutions

    OpenAIRE

    Ribeiro, R; Silva, Adrián; Faria, Joaquim; Gomes, Helder

    2015-01-01

    Catalytic wet peroxide oxidation (CWPO) is a well-known advanced oxidation process for the removal of organic pollutants from industrial process waters and wastewater. Specifically, CWPO employs hydrogen peroxide (H2O2) as oxidation source and a suitable catalyst to promote its decomposition via formation of hydroxyl radicals (HO•), which exhibit high oxidizing potential and serve as effective species in the destruction of a huge range of organic pollutants

  7. Preparation of rare-earth metal complex oxide catalysts for catalytic wet air oxidation

    Institute of Scientific and Technical Information of China (English)

    LI Ning; LI Guangming; YAO Zhenya; ZHAO Jianfu

    2007-01-01

    Catalytic wet air oxidation(CWAO)is one of the most promising technologies for pollution abatement.Developing catalysts with high activity and stability is crucial for the application of the CWAO process.The Mn/Ce complex oxide catalyrsts for CWAO of high concentration phenol containing wastewater were prepared by coprecipitation.The catalyst preparation conditions were optimized by using an orthogonal layout method and single-factor experimental analysis.The Mn/Ce serial catalysts were characterized by Brunauer-Emmett-Teller(BET)analysis and the metal cation leaching was measured by inductively coupled plasma torch-atomic emission spectrometry(ICP-AES).The results show that the catalysts have high catalytic activities even at a low temperature(80℃)and low oxygen partial pressure(0.5 MPa)in a batch reactor.The metallic ion leaching is comparatively low(Mn<6.577 mg/L and Ce<0.6910 mg/L,respectively)in the CWAO process.The phenol,CODCD and TOC removal efficiencies in the solution exceed 98.5% using the optimal catalyst(named CSP).The new catalyst would have a promising application in CWAO treatment of high concentration organic wastewater.

  8. Surface chemistry and catalytic properties of VOX/Ti-MCM-41 catalysts for dibenzothiophene oxidation in a biphasic system

    Science.gov (United States)

    González, J.; Chen, L. F.; Wang, J. A.; Manríquez, Ma.; Limas, R.; Schachat, P.; Navarrete, J.; Contreras, J. L.

    2016-08-01

    A series of vanadium oxide supported on Ti-MCM-41 catalysts was synthesized via the incipient impregnation method by varying the vanadia loading from 5 wt% to 10, 15, 20 and 25 wt%. These catalysts were characterized by a variety of advanced techniques for investigating their crystalline structure, textural properties, and surface chemistry information including surface acidity, reducibility, vanadium oxidation states, and morphological features. The catalytic activities of the catalysts were evaluated in a biphasic reaction system for oxidative desulfurization (ODS) of a model diesel containing 300 ppm of dibenzothiophene (DBT) where acetonitrile was used as extraction solvent and H2O2 as oxidant. ODS activity was found to be proportional to the V5+/(V4+ + V5+) values of the catalysts, indicating that the surface vanadium pentoxide (V2O5) was the active phase. Reaction temperature would influence significantly the ODS efficiency; high temperature, i.e., 80 °C, would lead to low ODS reaction due to the partial decomposition of oxidant. All the catalysts contained both Lewis and Brønsted acid sites but the former was predominant. The catalysts with low vanadia loading (5 or 10 wt%V2O5) had many Lewis acid sites and could strongly adsorb DBT molecule via the electron donation/acceptance action which resulted in an inhibition for the reaction of DBT with the surface peroxometallic species. The catalyst with high vanadia loading (25wt%V2O5/Ti-MCM-41) showed the highest catalytic activity and could remove 99.9% of DBT at 60 °C within 60 min.

  9. Catalytic oxidation with Al-Ce-Fe-PILC as a post-treatment system for coffee wet processing wastewater.

    Science.gov (United States)

    Sanabria, Nancy R; Peralta, Yury M; Montañez, Mardelly K; Rodríguez-Valencia, Nelson; Molina, Rafael; Moreno, Sonia

    2012-01-01

    The effluent from the anaerobic biological treatment of coffee wet processing wastewater (CWPW) contains a non-biodegradable compound that must be treated before it is discharged into a water source. In this paper, the wet hydrogen peroxide catalytic oxidation (WHPCO) process using Al-Ce-Fe-PILC catalysts was researched as a post-treatment system for CWPW and tested in a semi-batch reactor at atmospheric pressure and 25 °C. The Al-Ce-Fe-PILC achieved a high conversion rate of total phenolic compounds (70%) and mineralization to CO(2) (50%) after 5 h reaction time. The chemical oxygen demand (COD) of coffee processing wastewater after wet hydrogen peroxide catalytic oxidation was reduced in 66%. The combination of the two treatment methods, biological (developed by Cenicafé) and catalytic oxidation with Al-Ce-Fe-PILC, achieved a 97% reduction of COD in CWPW. Therefore, the WHPCO using Al-Ce-Fe-PILC catalysts is a viable alternative for the post-treatment of coffee processing wastewater. PMID:22907449

  10. Atomization energy approach to the quantitative evaluation of catalytic activities of metal oxides during dehydrogenation of MgH{sub 2}

    Energy Technology Data Exchange (ETDEWEB)

    Hirate, H., E-mail: hirate@silky.numse.nagoya-u.ac.jp [Department of Materials Science and Engineering, Graduate School of Engineering, Nagoya University, Furo-Cho, Chikusa-Ku, Nagoya 464-8603 (Japan); Morinaga, M.; Yukawa, H. [Department of Materials Science and Engineering, Graduate School of Engineering, Nagoya University, Furo-Cho, Chikusa-Ku, Nagoya 464-8603 (Japan); Nakai, H. [Department of Chemistry and Biochemistry, School of Advanced Science and Engineering, Waseda University, Okubo, Shinjuku-ku, Tokyo, 169-8555 (Japan)

    2011-09-15

    Research highlights: > Study of catalytic reaction on MgH{sub 2} and NaAlH{sub 4} using atomization energy concept. > Quantitative evaluation of catalytic activities of metal oxide for MgH{sub 2}. > Quantitative evaluation of catalytic activities of metal chlorides for NaAlH{sub 4}. > Observation of the O-H stretching mode on Nb{sub 2}O{sub 5}-catalyzed MgH{sub 2} in FT-IR. - Abstract: The hydrogen desorption reaction of magnesium hydride (MgH{sub 2}), MgH{sub 2} {yields} Mg + H{sub 2}, is accelerated by mixing catalytic metal oxides (e.g., Nb{sub 2}O{sub 5}). This catalytic effect is evaluated quantitatively using the atomization energy concept. The measured hydrogen desorption rate increases monotonously with increasing y x {Delta}E{sub O} values of metal oxides, M{sub x}O{sub y}. Here, {Delta}E{sub O,} is the atomization energy for the oxide ion in M{sub x}O{sub y}. This indicates that the oxide ion interacts mainly with hydrogen atom in MgH{sub 2}, in agreement with the observation of the O-H stretching mode in the FT-IR spectra during the dehydrogenation of the Nb{sub 2}O{sub 5}-catalyzed MgH{sub 2}. This approach is also proved to be useful for the catalytic analysis of metal chlorides (e.g., TiCl{sub 3}) on the decomposition reaction of NaAlH{sub 4} expressed as, NaAlH{sub 4} {yields} (1/3)Na{sub 3}AlH{sub 6} + (2/3)Al + H{sub 2}

  11. Catalytic performance and structural characterization of ferric oxide and its composite oxides supported gold catalysts for low-temperature CO oxidation

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    The preparation and catalytic activity of ferric oxide and its composite oxides supported gold catalysts for Iow-temperature CO oxidation were investigated detailedly, and characterized extensively by XRD, XPS, TPR, EC and XAFS techniques. It was found that containing highly dis persed Au of partially oxidized state, these nano-structured oxides supported Au/Fe2O3 and Au/NiFe2O4 catalysts had higher Iow-temperature activities. The possible catalytic active center is the gold of partially oxidized state (Auζ+).

  12. Chemical oxidation of anthracite with hydrogen peroxide via the Fenton reaction

    Science.gov (United States)

    Heard, I.; Senftle, F.E.

    1984-01-01

    Solutions of 30% H2O2 ranging from pH = 0 to pH = 11.5 have been used to oxidize anthracite at room temperature. The inorganic impurities, primarily pyrite, catalysed the oxidation and reduction of H2O2 (the Fenton reaction) to form the hydroxyl radical; the oxidation of the organic matter was minimal and was observed only in strong acidic solutions (pH reactions were completed in a much shorter time, the oxidation mechanism must have been of a different nature than that for the untreated anthracite. A qualitative model based on the catalytic decomposition of H2O2 by activated carbon sites in the coal surface is used to explain the oxidation of the demineralized anthracite. ?? 1984.

  13. Catalytic combustion of soot over Ru-doped mixed oxides catalysts

    Institute of Scientific and Technical Information of China (English)

    LF Nascimento; RF Martins; OA Serra

    2014-01-01

    We employed modified substrates as outer heterogeneous catalysts to reduce the soot originating from the incomplete die-sel combustion. Here, we proposed that ceria (CeO2)-based catalysts could lower the temperature at which soot combustion occurred from 610 ºC to values included in the operation range of diesel exhausts (270-400 ºC). Here, we used the sol-gel method to synthesize catalysts based on mixed oxides (ZnO:CeO2) deposited on cordierite substrates, and modified by ruthenium nanoparticles. The presence of ZnO in these mixed oxides produced defects associated with oxygen vacancies, improving thermal stability, redox potential, sulfur resistance, and oxygen storage. We evaluated the morphological and structural properties of the material by X-ray diffraction (XRD), Brumauer-emmett-teller method (BET), temperature programmed reduction (H2-TPR), scanning electron micros-copy (SEM), and transmission electron microscopy (TEM). We investigated how the addition of Ru (0.5 wt.%) affected the catalytic activity of ZnO:CeO2 in terms of soot combustion. Thermogravimetric analysis (TG/DTA) revealed that presence of the catalyst de-creased the soot combustion temperature by 250 ºC, indicating that the oxygen species arose at low temperatures, which was the main reason for the high reactivity of the oxidation reactions. Comparative analysis of soot emission by diffuse reflectance spectroscopy (DRS) showed that the catalyst containing Ru on the mixed oxide-impregnated cordierite samples efficiently oxidized soot in a diesel stationary motor:soot emission decreased 80%.

  14. Catalytic performance of cerium iron complex oxides for partial oxidation of methane to synthesis gas

    Institute of Scientific and Technical Information of China (English)

    LI Kongzhai; WANG Hua; WEI Yonggang; LIU Mingchun

    2008-01-01

    The cerium iron complex oxides oxygen carder was prepared by the co-precipitation method. The reactions between methane and lattice oxygen from the complex oxides were investigated in a fixed micro-reactor system. The reduced oxygen carrier could be re-oxidized by air and its initial state could be restored. The characterizations of the oxygen carriers were studied using XRD, O2-TPD, and H2-TPR. The results showed that the bulk lattice oxygen of CeO2-Fe2O3 was found to be suitable for the partial oxidation of methane to synthesis gas. There were two kinds of oxygen species on the oxygen carder: the stronger oxygen species that was responsible for the complete oxidation of methane, and the weaker oxygen species (bulk lattice oxygen) that was responsible for the selective oxidation of methane to CO and H2 at a higher temperature. Then, the lost bulk lattice oxygen could be selectively supplemented by air re-oxidation at an appropriate reaction con-dition. CeFeO3 appeared on the oxygen carrier after 10 successive redox cycles, however, it was not bad for the selectivity of CO and H2.

  15. Heterogeneous catalytic oxidative dehydrogenation of ethylbenzene to styrene with carbon dioxide

    Energy Technology Data Exchange (ETDEWEB)

    Badstube, T.; Papp, H. [Leipzig Univ. (Germany). Inst. fuer Technische Chemie; Kustrowski, P.; Dziembaj, R. [Jagiellonian Univ., Crakow (Poland). Faculty of Chemistry

    1998-12-31

    Alkaline promoted active carbon supported iron catalysts are very active in the oxidative dehydrogenation of ethylbenzene to styrene in the presence of carbon dioxide. The best results were obtained at 550 C for a Li-promoted catalyst with a conversion of ethylbenzene of 75% and a selectivity towards styrene of nearly 95%. These results are better than those obtained with industrial catalysts which perform the dehydrogenation process with an excess of water. The main product of the dehydrogenation reaction with CO{sub 2} was styrene, but the following by-products were detected - benzene and toluene. The selectivity towards toluene was always higher than towards benzene. We observed also the formation of carbon monoxide and water, which were produced with a constant molar ratio of about 0.8. The weight of the catalysts increased up to 20% during the reaction due to deposition of carbon. Using a too large excess of CO{sub 2} (CO{sub 2}/EB>10) was harmful for the styrene yield. The most favorable molar ratio of CO{sub 2} to EB was 10:1. No correlation between the molar ratios of reactants and the amount of deposited coke on the surface of catalysts was observed. The highest catalytic activity showed iron loaded D-90 catalysts which were promoted with alkali metals in a molar ratio of 1:10. Iron, nickel and cobalt loaded carbonized PPAN, PC, inorganic supports like Al{sub 2}O{sub 3}, SiO{sub 2}/ZrO{sub 2} or TiO{sub 2} respectively and commercial iron catalysts applied for styrene production did not show comparable catalytic activity in similar conditions. (orig.)

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

    OpenAIRE

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

    2008-01-01

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

  17. 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.

  18. Catalytic cracking of vegetable oil with metal oxides for biofuel production

    International Nuclear Information System (INIS)

    Highlights: • Biofuel was synthesized from vegetable oil by catalytic cracking. • Performance of six different metal catalysts was studied. • Influence of temperature and reaction time on the process was evaluated. • Methyl and ethyl esters are the major components of the biofuel synthesized. - Abstract: This study presents the utilization of metal oxides for the biofuel production from vegetable oil. The physical and chemical properties of the diesel-like products obtained, and the influence of reaction variables on the product distribution were investigated. Six different metal oxides (Co3O4, KOH, MoO3, NiO, V2O5, and ZnO) were employed as catalysts and the results indicated that the metal oxides are suitable for catalyzing the conversion of oil into organic liquid products (OLPs). The maximum conversion (87.6%) was obtained with V2O5 at 320 °C in 40 min whereas a minimum conversion (55.1%) was obtained with MoO3 at 390 °C in 30 min. The physical characteristics of the product obtained (density, specific gravity, higher heat value, flash point and kinematic viscosity), were in line with ASTM D6751 (B100) standards. The hydrocarbons majorly present in the product were found to be methyl and ethyl esters. Furthermore, OLPs obtained were distilled and separated into four components. The amount of light hydrocarbons, gasoline, kerosene and heavy oil like components obtained were 18.73%, 33.62%, 24.91% and 90.93%, respectively

  19. Catalytic and electrochemical behaviour of solid oxide fuel cell operated with simulated-biogas mixtures

    Science.gov (United States)

    Dang-Long, T.; Quang-Tuyen, T.; Shiratori, Y.

    2016-06-01

    Being produced from organic matters of wastes (bio-wastes) through a fermentation process, biogas mainly composed of CH4 and CO2 and can be considered as a secondary energy carrier derived from solar energy. To generate electricity from biogas through the electrochemical process in fuel cells is a state-of-the-art technology possessing higher energy conversion efficiency without harmful emissions compared to combustion process in heat engines. Getting benefits from high operating temperature such as direct internal reforming ability and activation of electrochemical reactions to increase overall system efficiency, solid oxide fuel cell (SOFC) system operated with biogas becomes a promising candidate for distributed power generator for rural applications leading to reductions of environmental issues caused by greenhouse effects and bio-wastes. CO2 reforming of CH4 and electrochemical oxidation of the produced syngas (H2-CO mixture) are two main reaction processes within porous anode material of SOFC. Here catalytic and electrochemical behavior of Ni-ScSZ (scandia stabilized-zirconia) anode in the feed of CH4-CO2 mixtures as simulated-biogas at 800 °C were evaluated. The results showed that CO2 had strong influences on both reaction processes. The increase in CO2 partial pressure resulted in the decrease in anode overvoltage, although open-circuit voltage was dropped. Besides that, the simulation result based on a power-law model for equimolar CH4-CO2 mixture revealed that coking hazard could be suppressed along the fuel flow channel in both open-circuit and closed-circuit conditions.

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

    Science.gov (United States)

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

    2015-04-29

    To fully characterize the Co(III)-'nitrene radical' species that are proposed as intermediates in nitrene transfer reactions mediated by cobalt(II) porphyrins, different combinations of cobalt(II) complexes of porphyrins and nitrene transfer reagents were combined, and the generated species were studied using EPR, UV-vis, IR, VCD, UHR-ESI-MS, and XANES/XAFS measurements. Reactions of cobalt(II) porphyrins 1(P1) (P1 = meso-tetraphenylporphyrin (TPP)) and 1(P2) (P2 = 3,5-Di(t)Bu-ChenPhyrin) with organic azides 2(Ns) (NsN3), 2(Ts) (TsN3), and 2(Troc) (TrocN3) led to the formation of mono-nitrene species 3(P1)(Ns), 3(P2)(Ts), and 3(P2)(Troc), respectively, which are best described as [Co(III)(por)(NR″(•-))] nitrene radicals (imidyl radicals) resulting from single electron transfer from the cobalt(II) porphyrin to the 'nitrene' moiety (Ns: R″ = -SO2-p-C6H5NO2; Ts: R″ = -SO2C6H6; Troc: R″ = -C(O)OCH2CCl3). Remarkably, the reaction of 1(P1) with N-nosyl iminoiodane (PhI═NNs) 4(Ns) led to the formation of a bis-nitrene species 5(P1)(Ns). This species is best described as a triple-radical complex [(por(•-))Co(III)(NR″(•-))2] containing three ligand-centered unpaired electrons: two nitrene radicals (NR″(•-)) and one oxidized porphyrin radical (por(•-)). Thus, the formation of the second nitrene radical involves another intramolecular one-electron transfer to the "nitrene" moiety, but now from the porphyrin ring instead of the metal center. Interestingly, this bis-nitrene species is observed only on reacting 4(Ns) with 1(P1). Reaction of the more bulky 1(P2) with 4(Ns) results again in formation of mainly mono-nitrene species 3(P2)(Ns) according to EPR and ESI-MS spectroscopic studies. The mono- and bis-nitrene species were initially expected to be five- and six-coordinate species, respectively, but XANES data revealed that both mono- and bis-nitrene species are six-coordinate O(h) species. The nature of the sixth ligand bound to cobalt(III) in the

  1. Kinetic determination of iodide by the oxidation reaction of benzidine with chloramine B

    International Nuclear Information System (INIS)

    Iodide catalyzed oxidation of benzidine with Chloramine B is studied for its possible application to kinetic determination of iodides. Based on the results of kinetic studies performed, optimal conditions for the catalytic reaction are revealed and a kinetic method for iodide determination is developed. The determination limit of iodide is 2x10-4 μg/ml. It was demonstrated that the proposed method can be used for the determination of iodides in water, soil, and kelp

  2. Catalytic wet-air oxidation of lignin in a three-phase reactor with aromatic aldehyde production

    Directory of Open Access Journals (Sweden)

    Sales F.G.

    2004-01-01

    Full Text Available In the present work a process of catalytic wet air oxidation of lignin obtained from sugar-cane bagasse is developed with the objective of producing vanillin, syringaldehyde and p-hydroxybenzaldehyde in a continuous regime. Palladium supported on g-alumina was used as the catalyst. The reactions in the lignin degradation and aldehyde production were described by a kinetic model as a system of complex parallel and series reactions, in which pseudo-first-order steps are found. For the purpose of producing aromatic aldehydes in continuous regime, a three-phase fluidized reactor was built, and it was operated using atmospheric air as the oxidizer. The best yield in aromatic aldehydes was of 12%. The experimental results were compatible with those values obtained by the pseudo-heterogeneous axial dispersion model (PHADM applied to the liquid phase.

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

    Science.gov (United States)

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

    2013-07-19

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

  4. Iron Oxides from Volcanic Soils as Potential Catalysts in the Water Gas Shift Reaction

    International Nuclear Information System (INIS)

    This study was focused on changes of the iron oxide mineralogy with temperature of two Chilean soils (Andisol and Ultisol) derived from volcanic materials and their use as iron-based catalysts in the water gas shift reaction (WGSR). Ultisol materials produced about twice as much hydrogen than did those from Andisol upon WGSR, but in both cases hydrogen yielding increased as the heating temperature of the soil materials increased from 124 deg. C to 500 deg. C. The room temperature Moessbauer spectra showed an increase of the relative proportion of the magnetically ordered components as temperature increased. Higher heating temperature produced a negative effect on the catalytic activity, whereas the organic matter destruction led to a positive effect, due to an increasing exposition of the iron oxide surfaces; heating the soil sample at 600 deg. C induced changes on the iron oxide mineralogy with a significant decrease of the catalytic activity

  5. Iron Oxides from Volcanic Soils as Potential Catalysts in the Water Gas Shift Reaction

    Science.gov (United States)

    Pizarro, C.; Escudey, M.; Moya, S. A.; Fabris, J. D.

    2005-04-01

    This study was focused on changes of the iron oxide mineralogy with temperature of two Chilean soils (Andisol and Ultisol) derived from volcanic materials and their use as iron-based catalysts in the water gas shift reaction (WGSR). Ultisol materials produced about twice as much hydrogen than did those from Andisol upon WGSR, but in both cases hydrogen yielding increased as the heating temperature of the soil materials increased from 124°C to 500°C. The room temperature Mössbauer spectra showed an increase of the relative proportion of the magnetically ordered components as temperature increased. Higher heating temperature produced a negative effect on the catalytic activity, whereas the organic matter destruction led to a positive effect, due to an increasing exposition of the iron oxide surfaces; heating the soil sample at 600 °C induced changes on the iron oxide mineralogy with a significant decrease of the catalytic activity.

  6. Selective Catalytic Oxidation of NH3 to N2 for Catalytic Combustion of Low Heating Value Gas under Lean/Rich Conditions

    Czech Academy of Sciences Publication Activity Database

    Kušar, H.M.J.; Ersson, A.G.; Vosecký, Martin; Järas, S.G.

    2005-01-01

    Roč. 58, 1-2 (2005), s. 25-32. ISSN 0926-3373 Institutional research plan: CEZ:AV0Z40720504 Keywords : catalytic combustion * selective catalytic oxidation * ammonia Subject RIV: CI - Industrial Chemistry, Chemical Engineering Impact factor: 3.809, year: 2005

  7. Selective catalytic reduction of nitrogen oxides with ammonia over microporous zeolite catalysts

    OpenAIRE

    VENNESTROM, PETER NICOLAI RAVNBORG

    2014-01-01

    With increasing legislative demands to remove nitrogen oxides (NOx) from automotive diesel exhaust, new catalyst systems are investigated and intensely studied in industry as well in academia. The most prevailing catalytic method of choice is the selective catalytic reduction (SCR) where non-toxic urea is used as a reductant for practical reasons. Usually urea is stored in a separate tank and once injected into the exhaust system it hydrolyses into the more aggressive reductant NH3 and CO2. ...

  8. Catalytic oxidative pyrolysis of spent organic ion exchange resins from nuclear power plants

    International Nuclear Information System (INIS)

    The spent IX resins from nuclear power reactors are highly active solid wastes generated during operations of nuclear reactors. Catalytic oxidative pyrolysis of these resins can lead to high volume reduction of these wastes. Low temperature pyrolysis of transition metal ion loaded IX resins in presence of nitrogen was carried out in order to optimize catalyst composition to achieve maximum weight reduction. Thermo gravimetric analysis of the pyrolysis residues was carried out in presence of air in order to compare the oxidative characteristics of transition metal oxide catalysts. Copper along with iron, chromium and nickel present in the spent IX resins gave the most efficient catalyst combination for catalytic and oxidative pyrolysis of the residues. During low temperature catalytic pyrolysis, 137Cesium volatility was estimated to be around 0.01% from cationic resins and around 0.1% from anionic resins. During oxidative pyrolysis at 700 degC, nearly 10 to 40% of 137Cesium was found to be released to off gases depending upon type of resin and catalyst loaded on to it. The oxidation of pyrolytic residues at 700 degC gave weight reduction of 15% for cationic resins and 93% for anionic resins. Catalytic oxidative pyrolysis is attractive for reducing weight and volume of spent cationic resins from PHWRs and VVERs. (author)

  9. Biodiesel by catalytic reactive distillation powered by metal oxides

    NARCIS (Netherlands)

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

    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

  10. 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. PMID:27553251

  11. System and method for selective catalytic reduction of nitrogen oxides in combustion exhaust gases

    Science.gov (United States)

    Sobolevskiy, Anatoly; Rossin, Joseph A

    2014-04-08

    A multi-stage selective catalytic reduction (SCR) unit (32) provides efficient reduction of NOx and other pollutants from about 50-550.degree. C. in a power plant (19). Hydrogen (24) and ammonia (29) are variably supplied to the SCR unit depending on temperature. An upstream portion (34) of the SCR unit catalyzes NOx+NH.sub.3 reactions above about 200.degree. C. A downstream portion (36) catalyzes NOx+H.sub.2 reactions below about 260.degree. C., and catalyzes oxidation of NH.sub.3, CO, and VOCs with oxygen in the exhaust above about 200.degree. C., efficiently removing NOx and other pollutants over a range of conditions with low slippage of NH.sub.3. An ammonia synthesis unit (28) may be connected to the SCR unit to provide NH.sub.3 as needed, avoiding transport and storage of ammonia or urea at the site. A carbonaceous gasification plant (18) on site may supply hydrogen and nitrogen to the ammonia synthesis unit, and hydrogen to the SCR unit.

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

    Science.gov (United States)

    Habershon, Scott

    2016-04-12

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

  13. Influence of physicochemical treatments on iron-based spent catalyst for catalytic oxidation of toluene.

    Science.gov (United States)

    Kim, Sang Chai; Shim, Wang Geun

    2008-06-15

    The catalytic oxidation of toluene was studied over an iron-based spent and regenerated catalysts. Air, hydrogen, or four different acid solutions (oxalic acid (C2H2O4), citric acid (C6H8O7), acetic acid (CH3COOH), and nitric acid (HNO3)) were employed to regenerate the spent catalyst. The properties of pretreated spent catalyst were characterized by the Brunauer Emmett Teller (BET), inductively coupled plasma (ICP), temperature programmed reduction (TPR), and X-ray diffraction (XRD) analyses. The air pretreatment significantly enhanced the catalytic activity of the spent catalyst in the pretreatment temperature range of 200-400 degrees C, but its catalytic activity diminished at the pretreatment temperature of 600 degrees C. The catalytic activity sequence with respect to the air pretreatment temperatures was 400 degrees C>200 degrees C>parent>600 degrees C. The TPR results indicated that the catalytic activity was correlated with both the oxygen mobility and the amount of available oxygen on the catalyst. In contrast, the hydrogen pretreatment had a negative effect on the catalytic activity, and toluene conversion decreased with increasing pretreatment temperatures (200-600 degrees C). The XRD and TPR results confirmed the formation of metallic iron which had a negative effect on the catalytic activity with increasing pretreatment temperature. The acid pretreatment improved the catalytic activity of the spent catalyst. The catalytic activity sequence with respect to different acids pretreatment was found to be oxalic acid>citric acid>acetic acid>or=nitric acid>parent. The TPR results of acid pretreated samples showed an increased amount of available oxygen which gave a positive effect on the catalytic activity. Accordingly, air or acid pretreatments were more promising methods of regenerating the iron-based spent catalyst. In particular, the oxalic acid pretreatment was found to be most effective in the formation of FeC2O4 species which contributed highly to the

  14. Influence of physicochemical treatments on iron-based spent catalyst for catalytic oxidation of toluene

    International Nuclear Information System (INIS)

    The catalytic oxidation of toluene was studied over an iron-based spent and regenerated catalysts. Air, hydrogen, or four different acid solutions (oxalic acid (C2H2O4), citric acid (C6H8O7), acetic acid (CH3COOH), and nitric acid (HNO3)) were employed to regenerate the spent catalyst. The properties of pretreated spent catalyst were characterized by the Brunauer Emmett Teller (BET), inductively coupled plasma (ICP), temperature programmed reduction (TPR), and X-ray diffraction (XRD) analyses. The air pretreatment significantly enhanced the catalytic activity of the spent catalyst in the pretreatment temperature range of 200-400 deg. C, but its catalytic activity diminished at the pretreatment temperature of 600 deg. C. The catalytic activity sequence with respect to the air pretreatment temperatures was 400 deg. C > 200 deg. C > parent > 600 deg. C. The TPR results indicated that the catalytic activity was correlated with both the oxygen mobility and the amount of available oxygen on the catalyst. In contrast, the hydrogen pretreatment had a negative effect on the catalytic activity, and toluene conversion decreased with increasing pretreatment temperatures (200-600 deg. C). The XRD and TPR results confirmed the formation of metallic iron which had a negative effect on the catalytic activity with increasing pretreatment temperature. The acid pretreatment improved the catalytic activity of the spent catalyst. The catalytic activity sequence with respect to different acids pretreatment was found to be oxalic acid > citric acid > acetic acid ≥ nitric acid > parent. The TPR results of acid pretreated samples showed an increased amount of available oxygen which gave a positive effect on the catalytic activity. Accordingly, air or acid pretreatments were more promising methods of regenerating the iron-based spent catalyst. In particular, the oxalic acid pretreatment was found to be most effective in the formation of FeC2O4 species which contributed highly to the

  15. Preparation of thin film gold based catalysts for oxidation reactions in liquid and gas phases

    International Nuclear Information System (INIS)

    This work deals with the preparation of gold on titania catalysts to make catalytic films in the less than 100 nm thickness area and its comparison with usual powder catalyst in catalytic oxidation reactions in gas and liquid phases. Titania was coated on glass plates with different thicknesses, but with ultra-low surface roughness (< 5 Å). Gold deposition was performed with usual chemical method for catalysts preparation, that is deposition–precipitation with urea. Transmission electron microscopy showed that planar samples are decorated with a high quantity (> 10 wt.% with respect to TiO2) of gold nanoparticles smaller than 2.5 nm, with a narrow size distribution. Activity in CO oxidation demonstrates the catalytic behavior of the planar samples, although they are less active than powder catalyst because of the different geometries of the reactors and catalysts. In contrast, their catalytic performances in liquid phase, benzyl alcohol oxidation, are comparable. These results validate the concept that gold planar catalysts prepared by chemical methods can present similar catalytic behavior as real powder gold catalysts. Such planar catalysts could be useful for bridging the material gap between real and model catalysts in advanced techniques, such as scanning tunnelling microscopy and spectroscopy or high-pressure photoelectron spectroscopy. - Highlights: ► Preparation of thin film of TiO2 (pure anatase) on glass with a low roughness (< 5 Å) ► High density of small gold nanoparticles on planar substrates by a chemical method ► Planar catalysts active in both gas and liquid phase oxidation reactions ► Bridging of the material gap between real and model catalysts

  16. Water oxidation catalysis: an amorphous quaternary Ba-Sr-Co-Fe oxide as a promising electrocatalyst for the oxygen-evolution reaction.

    Science.gov (United States)

    Zhang, Cuijuan; Berlinguette, Curtis P; Trudel, Simon

    2016-01-25

    We present an amorphous quaternary Ba-Sr-Co-Fe oxide (a-BSCF) with a specific stoichiometry, readily fabricated via a photochemical decomposition method. a-BSCF demonstrates high catalytic activity towards the oxygen-evolution reaction (OER). PMID:26659269

  17. Synthesis, characterization and photo catalytic studies of the composites by tantalum oxide and zinc oxide nanorods

    Science.gov (United States)

    Chennakesavulu, K.; Reddy, M. Madhusudhana; Reddy, G. Ramanjaneya; Rabel, A. M.; Brijitta, J.; Vinita, V.; Sasipraba, T.; Sreeramulu, J.

    2015-07-01

    In-situ synthesis of ZnO:Ta2O5 composites in basic medium by using tantalum chloride and zinc chloride as precursors. The prepared composites were characterized by Fourier Transform Infrared spectroscopy (FTIR), confocal Raman spectroscopy, diffuse reflectance UV-Vis spectrophotometer (DRS), X-ray diffraction (XRD), Brunauer-Emmett-Teller (BET) method, N2-sorption isotherms, Thermo Gravimetric Analysis (TGA), High Resolution Transmission Electron Microscope (HRTEM), X-ray Photoelectron Spectroscopy (XPS), and Field Emission Scanning Electron Microscopy (FESEM/EDS). The composite materials were used as photocatalyst in the degradation Rhodamine-B (RhB) dye under visible light irradiation. The catalytic activity and removal percentage of the dye was determined by the spectrophotometric method. This indicates the percentage of degradation was more for the ZnO:Ta2O5 composites. The kinetic parameter obeys pseudo-first order reaction. It may be due to fixed amount the catalysts and concentration of dye solution. The catalytic activity of the recycled ZnO:Ta2O5 catalyst was compared with fresh catalyst.

  18. Understanding Catalytic Activity Trends for NO Decomposition and CO Oxidation using Density Functional Theory and Microkinetic Modeling

    DEFF Research Database (Denmark)

    Falsig, Hanne

    towards rationalizing trends in catalytic activity of transition metal catalysts for NO decomposition by combining microkinetic modelling with density functional theory calculations. We establish the full potential energy diagram for the direct NO decomposition reaction over stepped transition...... Pt are the best direct NO decomposition catalysts among the 3d, 4d, and 5d metals. We analyze the NO decomposition reaction in terms of the Sabatier analysis and a Sabatier–Gibbs-type analysis and obtain an activity trend in agreement with experimental results. We show specifically why the key...... problem in using transition metal surfaces to catalyze direct NO decomposition is their significant relative overbinding of atomic oxygen compared to atomic nitrogen. We calculate adsorption and transition state energies for the full CO oxidation reaction pathway by the use of DFT for a number of...

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

    Science.gov (United States)

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

    2013-04-17

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

  20. In situ infrared study of adsorbed species during catalytic oxidation and carbon dioxide adsorption

    Science.gov (United States)

    Khatri, Rajesh A.

    2005-11-01

    Hydrogen is considered to be the fuel of the next century. Hydrogen can be produced by either water splitting using the solar or nuclear energy or by catalytic cracking and reforming of the fossil fuels. The water splitting process using solar energy and photovoltaics is a clean way to produce hydrogen, but it suffers from very low efficiency. A promising scheme to produce H 2 from natural gas involves following steps: (i) partial oxidation and reforming of natural gas to syngas, (ii) water-gas shift reaction to convert CO in the syngas to additional H2, (iii) separation of the H2 from CO2, and (iv) CO2 sequestration. The requirements for the above scheme are (i) a highly active coke resistant catalyst for generation of syngas by direct partial oxidation, (ii) a highly active sulfur tolerant catalyst for the water-gas shift reaction, and (iii) a low cost sorbent with high CO2 adsorption capacity for CO2 sequestration. This dissertation will address the mechanisms of partial oxidation, CO2 adsorption, and water-gas shift catalysis using in situ IR spectroscopy coupled with mass spectrometry (MS). The results from these studies will lead to a better understanding of the reaction mechanism and design of both the catalyst and sorbent for production of hydrogen with zero emissions. Partial oxidation of methane is studied over Rh/Al2O 3 catalyst to elucidate the reaction mechanism for synthesis gas formation. The product lead-lag relationship observed with in situ IR and MS results revealed that syngas is produced via a two-step reforming mechanism: the first step involving total oxidation of CH4 to CO2 and H 2O and the second step involving the reforming of unconverted methane with CO2 and H2O to form syngas. Furthermore, the Rh on the catalyst surface remains predominantly in the partially oxidized state (Rhdelta+ and Rh0). For the water-gas shift reaction, addition of Re to the Ni/CeO2 catalyst enhanced the water gas shift activity by a factor of three. The activity

  1. Influences of Reaction Parameters on the Product of a Geothermite Reaction: A Multi-Component Oxidation-Reduction Reaction Study

    OpenAIRE

    Faierson, Eric J.

    2009-01-01

    This study investigated an oxidation-reduction reaction involving a mixture of minerals, glass, and aluminum that exhibited thermite-type reaction behavior. Thermite reactions are a class of Self-propagating High-temperature Synthesis (SHS) reactions. Chemical reactions between raw minerals and a reducing agent, which exhibit thermite-type reaction behavior, are termed geothermite reactions by the author. Geothermite reactions have the potential for use in In-Situ Resource Utilization (ISRU...

  2. 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. PMID:24907577

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

    Energy Technology Data Exchange (ETDEWEB)

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

    1996-10-28

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

  4. Catalytic combustion of toluene over a copper-Manganese-silver mixed-oxide catalyst supported on a washcoated ceramic monolith

    Energy Technology Data Exchange (ETDEWEB)

    Zhou, J.C.; Jiang, W. [School of Chemistry and Chemical Engineering, Southeast University, Nanjing (China); Li, Y.D. [Tianjin Key Laboratory of Applied Catalysis Science and Technology and State Key Laboratory for Chemical Engineering (Tianjin University), Tianjin University, Tianjin (China); Wu, D.F.

    2009-10-15

    Monolithic catalysts were prepared by washcoating an alumina sol and then impregnating Cu-Mn-Ag mixed oxides onto cordierite substrates. The effects of the preparation parameters including the Ag/Cu/Mn ratio, the total amount of active phase and the loading of washcoat, and the reaction conditions, e.g., the space velocity and the oxygen/toluene ratio on the catalytic performance for the combustion of toluene were investigated. It is shown that the Cu-Mn-Ag oxides are very active for the combustion of toluene and that the highest catalytic activity is achieved over a monolithic catalyst containing 14.7 wt % of washcoat and 21.2 wt % of active phase with a Ag/Cu/Mn molar ratio of 13.8/43.1/43.1. It is also seen that the optimum catalyst has a good catalytic stability and exhibits an excellent activity not only at a rather high space velocity but also within a wide range of oxygen/toluene ratios. (Abstract Copyright [2009], Wiley Periodicals, Inc.)

  5. Low-temperature plasma-catalytic oxidation of formaldehyde in atmospheric pressure gas streams

    International Nuclear Information System (INIS)

    Formaldehyde (HCHO) is a typical air pollutant capable of causing serious health disorders in human beings. This work reports plasma-catalytic oxidation of formaldehyde in gas streams via dielectric barrier discharges over Ag/CeO2 pellets at atmospheric pressure and 70 0C. With a feed gas mixture of 276 ppm HCHO, 21.0% O2, 1.0% H2O in N2, ∼99% of formaldehyde can be effectively destructed with an 86% oxidative conversion into CO2 at GHSV of 16500 h-1 and input discharge energy density of 108 J l-1. At the same experimental conditions, the conversion percentages of HCHO to CO2 from pure plasma-induced oxidation (discharges over fused silica pellets) and from pure catalytic oxidation over Ag/CeO2 (without discharges) are 6% and 33% only. The above results and the CO plasma-catalytic oxidation experiments imply that the plasma-generated short-lived gas phase radicals, such as O and HO2, play important roles in the catalytic redox circles of Ag/CeO2 to oxidize HCHO and CO to CO2

  6. Steady-state kinetics with nitric oxide reductase (NOR): new considerations on substrate inhibition profile and catalytic mechanism.

    Science.gov (United States)

    Duarte, Américo G; Cordas, Cristina M; Moura, José J G; Moura, Isabel

    2014-03-01

    Nitric oxide reductase (NOR) from denitrifying bacteria is an integral membrane protein that catalyses the two electron reduction of NO to N2O, as part of the denitrification process, being responsible for an exclusive reaction, the NN bond formation, the key step of this metabolic pathway. Additionally, this class of enzymes also presents residual oxidoreductase activity, reducing O2 to H2O in a four electron/proton reaction. In this work we report, for the first time, steady-state kinetics with the Pseudomonas nautica NOR, either in the presence of its physiological electron donor (cyt. c552) or immobilised on a graphite electrode surface, in the presence of its known substrates, namely NO or O2. The obtained results show that the enzyme has high affinity for its natural substrate, NO, and different kinetic profiles according to the electron donor used. The kinetic data, as shown by the pH dependence, is modelled by ionisable amino acid residues nearby the di-nuclear catalytic site. The catalytic mechanism is revised and a mononitrosyl-non-heme Fe complex (FeB(II)-NO) species is favoured as the first catalytic intermediate involved on the NO reduction. PMID:24412239

  7. Session 6: Water depollution from aniline and phenol by air oxidation and adsorptive-catalytic oxidation in liquid phase

    Energy Technology Data Exchange (ETDEWEB)

    Dobrynkin, N.M.; Batygina, M.V.; Noskov, A.S. [Boreskov Institute of Catalysis of Siberian Branch of Russian Academy of Sciences, Pr. Ak. Lavrentieva (Russian Federation)

    2004-07-01

    This paper is devoted to development of carbon catalysts and application of catalytic wet air oxidation for deep cleaning of polluted waters. The described catalysts and method are solving the problem of development environmentally reliable method for fluids treatment and allow carrying out the adsorption of pollutants on carbon CAPM (catalytically active porous material) with following regeneration of the CAPM without the loss of adsorptive qualities. The experiments have shown a principal capability simultaneously to use carbon CAPM as adsorbent and either as catalyst, or as a catalyst support for oxidation of aniline and phenol in water solutions. (authors)

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

    Science.gov (United States)

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

    2015-08-01

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

  9. Radwaste solidification modifications by means of nitrogen oxides catalytic abatement

    International Nuclear Information System (INIS)

    In the treatment and solidification of medium and high level radioactive wastes, large amounts of NO /sub x/ are produced, which are normally scrubbed with nitric acid or alkaline solutions. In this way big volumes of secondary wastes containing high nitrate concentrations which cannot be easily discharged are produced. The application of the NO /sub x/ catalytic abatement with selective ammonia reduction would permit to avoid this problem, with large cost savings. Two practical examples have been examined: a bituminization plant and a pot vitrification plant referred to the Italian EUREX Reprocessing Pilot Plant. 416,000 and 362,000 $/y respectively would be saved by replacing scrubbing towers with a catalytic reactor

  10. Rare earth oxide aero- and xerogels. Tuning porosity and catalytic properties

    Energy Technology Data Exchange (ETDEWEB)

    Neumann, Bjoern

    2013-11-15

    Heterogeneous catalysts to this day are still largely developed on the basis of trial and error. This is due to the great difficulty of creating custom-designed structures at the nanometer scale using traditional preparation methods. In the course of recent rapid developments in the material sciences, however, it has become possible to create materials with custom-designed properties from the macroscopic down into the nanometer range. The purpose of the present study was to make use of this potential for catalysis. The task was to modify the porosity and composition of selected rare earth oxides that promise well as catalysts with the goal of obtaining good results in terms of oxidative reactions and oxidative coupling. One major focus was on chemical sol-gel methods and in particular on what is referred to as the epoxide addition method. Extensive work was put into the characterisation and catalytic testing of aerogels and xerogels of pure rare earth oxides as well as of hybrid systems of rare earth oxides and aluminium oxide. Furthermore, thin xerogel films and macroporous monoliths were produced, the latter using a direct foaming method. The results of this work confirm the high potential of sol-gel chemistry for making porous materials of variable and controllable porosity and composition available for heterogeneous catalysis and creating more powerful catalysts. [German] Bis heute werden heterogene Katalysatoren ueberwiegend per ''trial and error'' entwickelt. Dies liegt daran, dass es mit Hilfe der traditionellen Herstellungsmethoden sehr schwierig ist, auf der Nanometerskala Strukturen gezielt herzustellen. Im Zuge der rasanten Entwicklungen in den Materialwissenschaften ist es jedoch moeglich geworden, verschiedenste Materialen mit massgeschneiderten Eigenschaften vom makroskopischen bis hinein in den Nanometerbereich herzustellen. Ziel dieser Arbeit war es, dieses Potential fuer die Katalyse zu nutzen. Dabei bestand die Aufgabe darin

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

    Science.gov (United States)

    Barkhordarian, Gagik; Klassen, Thomas; Bormann, Rüdiger

    2006-06-01

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

  12. Hematite concave nanocubes and their superior catalytic activity for low temperature CO oxidation

    Science.gov (United States)

    Liang, Hanfeng; Jiang, Xinde; Qi, Zhengbing; Chen, Wei; Wu, Zhengtao; Xu, Binbin; Wang, Zhoucheng; Mi, Jinxiao; Li, Qingbiao

    2014-06-01

    Hematite (α-Fe2O3) concave nanocubes bound by high-index {134&cmb.macr;4} and {123&cmb.macr;8} facets were synthesized and their catalytic activity for CO oxidation were also investigated.Hematite (α-Fe2O3) concave nanocubes bound by high-index {134&cmb.macr;4} and {123&cmb.macr;8} facets were synthesized and their catalytic activity for CO oxidation were also investigated. Electronic supplementary information (ESI) available. See DOI: 10.1039/c4nr00552j

  13. Preparation of Molecular Sieve Catalyst and Application in the Catalytic Oxidation Treatment of Waste Water

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    @@ Citric acid is an important additive in foods, cosmetics, medicine and so on, but it discharges about 10 ton of factory effluent when 1 ton of citric acid is produced. The COD of the factory effluent is near 20000 mg/L. The treatment of citric acid factory effluent is a serious problem in environmental chemistry. It is found that molecular sieve support metal complexes have high catalytic activity in aerobic oxidation of alkene [1,2]. In this paper, a kind of molecular sieve catalyst was prepared. The catalyst was used for the treatment of citric acid factory effluent by method of catalytic oxygen oxidation.

  14. Influence of method of preparation of Pt Ru/C electrocatalysts on the catalytic activity for the ethanol oxidation reaction in acidic medium; Influencia do metodo de preparacao de eletrocatalisadores PtRu/C sobre a atividade catalitica frente a reacao de oxidacao de etanol em meio acido

    Energy Technology Data Exchange (ETDEWEB)

    Gomes, Walber dos Santos; Silva, Uriel Lean Valente; Souza, Jose Pio Iudice de, E-mail: jpio@ufpa.br [Universidade Federal do Para, (UFPA), Belem, PA (Brazil). Instituto de Ciencias Exatas e Naturais. Faculdade de Quimica

    2013-09-01

    In this work the influence of variations in the borohydrate reduction method on the properties of Pt Ru/C electrocatalysts was investigated. The electrocatalysts were prepared using 1:1 ; 2:1; 5:1; 50:1 and 250:1 molar ratios of NaBH{sub 4} to metals. The reduction was also performed by dripping or by fast addition of the solution. The results showed that Pt Ru nanoparticles obtained by fast addition had the smallest crystallite sizes. It was also noted that the catalytic activity increased as the borohydrate:metal molar ratio increased. The Pt Ru/C electrocatalysts (50:1) obtained by fast addition presented the best catalytic activity for ethanol electro-oxidation. (author)

  15. Surface composition and catalytic activity of La-Fe mixed oxides for methane oxidation

    Energy Technology Data Exchange (ETDEWEB)

    Liu, Fengxiang [School of Chemistry, Beijing Institute of Technology, Liangxiang East Road, Beijing 102488 (China); Li, Zhanping [Analysis Center, Tsinghua University, Beijing 100084 (China); Ma, Hongwei [School of Chemistry, Beijing Institute of Technology, Liangxiang East Road, Beijing 102488 (China); Gao, Zhiming, E-mail: zgao@bit.edu.cn [School of Chemistry, Beijing Institute of Technology, Liangxiang East Road, Beijing 102488 (China)

    2015-10-01

    Graphical abstract: - Highlights: • The sample with La/Fe atomic ratio of 0.94 is single phase perovskite La{sub 0.94}FeO{sub 3−d}. • The excess ironic oxide exists on the surface of the perovskite crystallites. • La{sup 3+} ions are enriched on surface of the oxides even for the La{sub 0.68}Fe sample. - Abstract: Four La-Fe oxide samples with La/Fe atomic ratio y = 1.02 ∼ 0.68 (denoted as LayFe) were prepared by the citrate method. The samples had a decreased specific surface area with the La/Fe atomic ratio decreasing. XRD pattern proved that the sample La{sub 0.94}Fe is single phase perovskite La{sub 0.94}FeO{sub 3−d}. Phase composition of the samples was estimated by the Rietveld refinement method. XPS analyses indicate that La{sup 3+} ions are enriched on surface of crystallites for all the samples, and surface carbonate ions are relatively abundant on the samples La{sub 1.02}Fe and La{sub 0.94}Fe. Catalytic activity for methane oxidation per unit surface area of the samples is in the order of La{sub 0.68}Fe > La{sub 0.76}Fe > La{sub 0.94}Fe > La{sub 1.02}Fe both in the presence and in the absence of gaseous oxygen. A reason for this order would be the higher concentration of Fe{sup 3+} ion on the surface of the samples La{sub 0.68}Fe and La{sub 0.76}Fe.

  16. Efficient oxidation of benzyl alcohol with heteropolytungstate as reaction-controlled phase-transfer catalyst

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    A series of heteropolytungstates has been synthesized and utilized as catalysts to catalyze oxidation of benzyl alcohol with aqueous hydrogen peroxide. The results indicated that three of these catalysts showed the properties of reaction-controlled phasetransfer catalysis, and they had excellent catalytic ability to the oxidation of benzyl alcohol. No other by-products were detected by gas chromatography. Once the hydrogen peroxide was consumed completely, the catalyst precipitated from solvent, and the results of the catalyst recycle showed that the catalyst had high stability.

  17. Preparation of hierarchical layer-stacking Mn-Ce composite oxide for catalytic total oxidation of VOCs

    Institute of Scientific and Technical Information of China (English)

    唐文翔; 武晓峰; 刘刚; 李双德; 李东艳; 李文辉; 陈运法

    2015-01-01

    Hierarchical layer-stacking Mn-Ce composite oxide with mesoporous structure was firstly prepared by a simple precipita-tion/decomposition procedure with oxalate precursor and the complete catalytic oxidation of VOCs (benzene, toluene and ethyl ace-tate) were examined. The Mn-Ce oxalate precursor was obtained from metal salt and oxalic acid without any additives. The resulting materials were characterized by X-ray diffraction (XRD), Brunauer-Emmett-Teller (BET), scanning electron microscopy (SEM), en-ergy dispersive X-ray spectroscopy (EDX), hydrogen temperature programmed reduction (H2-TPR) and X-ray photoelectron spec-troscopy (XPS). Compared with Mn-Ce composite oxide synthesized through a traditional method (Na2CO3 route), the hierarchical layer-stacking Mn-Ce composite oxide exhibited higher catalytic activity in the complete oxidation of volatile organic compounds (VOCs). By means of testing, the data revealed that the hierarchical layer-stacking Mn-Ce composite oxide possessed superior physiochemical properties such as good low-temperature reducibility, high manganese oxidation state and rich adsorbed surface oxy-gen species which resulted in the enhancement of catalytic abilities.

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

    Indian Academy of Sciences (India)

    B Khanbabaei; A Ghasemizad; S Khoshbinfar

    2014-09-01

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

  19. Performance of a Novel Hydrophobic Mesoporous Material for High Temperature Catalytic Oxidation of Naphthalene

    Directory of Open Access Journals (Sweden)

    Guotao Zhao

    2014-01-01

    Full Text Available A high surface area, hydrophobic mesoporous material, MFS, has been successfully synthesized by a hydrothermal synthesis method using a perfluorinated surfactant, SURFLON S-386, as the single template. N2 adsorption and TEM were employed to characterize the pore structure and morphology of MFS. Static water adsorption test indicates that the hydrophobicity of MFS is significantly higher than that of MCM-41. XPS and Py-GC/MS analysis confirmed the existence of perfluoroalkyl groups in MFS which led to its high hydrophobicity. MFS was used as a support for CuO in experiments of catalytic combustion of naphthalene, where it showed a significant advantage over MCM-41 and ZSM-5. SEM was helpful in understanding why CuO-MFS performed so well in the catalytic combustion of naphthalene. Experimental results indicated that MFS was a suitable support for catalytic combustion of large molecular organic compounds, especially for some high temperature catalytic reactions when water vapor was present.

  20. Synthesis of p-Hydroxybenzaldehyde by Liquid-phase Catalytic Oxidation of p-Cresol over PVDF Modified Cobalt Pyrophosphate

    Institute of Scientific and Technical Information of China (English)

    ZHANG Yi-bo; WANG De-qiang; MIAO Zhen-zhen; PAN Xi-qiang; ZHANG Zhen-dong; YANG Xiang-guang

    2013-01-01

    The influence of the wettability of a catalyst on the performance of the liquid phase oxidation of p-cresol was investigated.It was found that the surface hydrophobicity of a catalyst,which can be changed by modification with various loadings of polyvinylidene fluoride(PVDF),has a promotion effect on the catalytic performance.At the same time,the reaction parameters such as oxygen pressure,molar ratio of NaOH to p-cresol,reaction temperature and time on the catalytic performance in the liquid-phase oxidation of p-cresol were optimized.As a result,10%(mass fraction) PVDF modified cobalt pyrophosphate gave the highest conversion of 94.2% of p-cresol with a selectivity of 94.4% for p-hydroxybenzaldehyde at 348 K and a molar ratio of 4:1 of NaOH/p-cresol and an oxygen pressure of 1.0 MPa for 3 h.

  1. Heterogeneously Catalyzed Oxidation Reactions Using Molecular Oxygen

    OpenAIRE

    Beier, Matthias Josef; Grunwaldt, Jan-Dierk; Jensen, Anker Degn; Kontogeorgis, Georgios

    2011-01-01

    Denne afhandling giver indledningsvist et overblik over heterogene kobber og sølv katalysatorer til selektiv oxidation i væskefase og sammenligner virkningsgraden og katalytiske egenskaber af disse med den i vidt omfang benyttede guld katalysator. Resultater fra litteraturen er opsummeret for alkohol oxidation, epoxidation, amin oxidation, fenyl hydroxylation, silan og sulfid oxidation, (side-kæde) oxidation af alkyl aromatiske stoffer, hydroquinon oxidation samt cyklohexan oxidation. Det er ...

  2. Catalytic oxidation of water and alcohols by a robust iron(iii) complex bearing a cross-bridged cyclam ligand.

    Science.gov (United States)

    Tan, Peng; Kwong, Hoi-Ki; Lau, Tai-Chu

    2015-08-01

    An iron(iii) complex bearing a cross-bridged cyclam ligand (4,11-dimethyl-1,4,8,11-tetraazabicyclo[6.6.2]hexadecane) is an efficient catalyst for the oxidation of both water and alcohols using sodium periodate as the oxidant. In catalytic water oxidation a maximum turnover number (TON) of 1030 is achieved, while in catalytic alcohol oxidation >95% conversions and yields can be obtained. PMID:26126521

  3. CuO-CeO2 binary oxide nanoplates: Synthesis, characterization, and catalytic performance for benzene oxidation

    International Nuclear Information System (INIS)

    This work reports the first synthesis of CuO-CeO2 binary oxides with a plate-like morphology by a solvothermal method. The as-prepared CuO-CeO2 nanoplates calcined at 400 oC were characterized by X-ray diffraction, scanning electron microscopy, transmission electron microscopy, X-ray photoelectron spectrum, and tested for catalytic oxidation of dilute benzene in air. Various structural characterizations showed that large amounts of copper species were exposed on the CuO-CeO2 nanoplate surface. The effect of the synthesis conditions on the structure of the product, as well as the growth process of the nanoplates, has been studied and discussed. The CuO-CeO2 nanoplates exhibited an excellent catalytic activity for benzene oxidation despite its relatively low surface area and could catalyze the complete oxidation of benzene at a temperature as low as 240 oC.

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

    Institute of Scientific and Technical Information of China (English)

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

    2003-01-01

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

  5. Effect of solvents on reactions of oxidation with aliphatic peroxyacids

    OpenAIRE

    Natalia Matsyuk, Mariya Matsyuk; Volodymur Dutka

    2013-01-01

    Organic solvents effect on the reactions of oxidation involving aliphatic peroxyacids was studied. It was found the kinetic and activation parameters of the oxidation of aniline. It is shown that the reaction medium has a significant effect on the rate of the process. The epoxidation reaction of ?-pinene and ?3-karen by peroxydecanoic acid was studied. It was obtain the equation of correlation that connecting speed reaction with the basic physicochemical properties of solvents.

  6. Copper(II)–imida‐salen Complexes Encapsulated into NaY Zeolite for Oxidations Reactions

    DEFF Research Database (Denmark)

    Kuźniarska‐Biernacka, Iwona; Carvalho, M. Alice; Rasmussen, Søren Birk;

    2013-01-01

    heterogeneous catalysts were characterized by SEM, XRD, FTIR, EPR and Raman spectroscopy as well as by chemical analysis. The structures of the copper(II) complexes were proposed on the basis of theoretical studies (DFT). The catalytic activities of the encapsulated copper(II) complexes in NaY were compared......The oxidation of phenol, cychohexanol and hydroquinone has been screened in the presence of copper(II) complexes with the Schiff‐base salen ligand, 1,5‐bis[(E)‐5‐chloro‐2‐hydroxybenzylideneamino]‐1H‐imidazole‐4‐carbonitrile, and encapsulated into NaY zeolite by using two different methods. The new...... with their homogeneous counterparts. The results show higher or similar substrate conversion when compared with the free complex in all the reactions tested. After their use in catalytic reaction, these catalysts were found to be reusable without loss of activity....

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

    International Nuclear Information System (INIS)

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

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2000-01-01

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

  9. Electro-catalytic oxidation device for removing carbon from a fuel reformate

    Science.gov (United States)

    Liu, Di-Jia

    2010-02-23

    An electro-catalytic oxidation device (ECOD) for the removal of contaminates, preferably carbonaceous materials, from an influent comprising an ECOD anode, an ECOD cathode, and an ECOD electrolyte. The ECOD anode is at a temperature whereby the contaminate collects on the surface of the ECOD anode as a buildup. The ECOD anode is electrically connected to the ECOD cathode, which consumes the buildup producing electricity and carbon dioxide. The ECOD anode is porous and chemically active to the electro-catalytic oxidation of the contaminate. The ECOD cathode is exposed to oxygen, and made of a material which promotes the electro-chemical reduction of oxygen to oxidized ions. The ECOD electrolyte is non-permeable to gas, electrically insulating and a conductor to oxidized. The ECOD anode is connected to the fuel reformer and the fuel cell. The ECOD electrolyte is between and in ionic contact with the ECOD anode and the ECOD cathode.

  10. Porous manganese oxide synthesized through organic-electrolyte templates and their catalytic applications

    International Nuclear Information System (INIS)

    We report a facile approach to the preparation of porous manganese oxide materials by the organic-electrolyte templates based on strategy. The final products are thoroughly characterized by X-ray diffraction (XRD), thermogravimetric analysis (TGA), field-emission scanning electron microscopy (SEM), transmission electron microscopy (TEM), Fourier transform infrared spectroscopy (FT-IR), X-ray photoelectron spectroscopy (XPS), inductively coupled plasma-optical emission spectroscopy (ICP-OES), and Brunauer-Emmett-Teller (BET) techniques. The results reveal that porosity (pore size and distribution, surface area) of these manganese oxides has strong relationship with the templates used, which implies a simple way to obtain a series of porous materials. By comparing the catalytic effects of these manganese oxides in oxidation of indene and benzyl alcohol, we find that the pore size and distribution are also crucial to the catalytic properties of these porous materials.

  11. Importance of the oxygen bond strength for catalytic activity in soot oxidation

    DEFF Research Database (Denmark)

    Christensen, Jakob M.; Grunwaldt, Jan-Dierk; Jensen, Anker D.

    2016-01-01

    (loose contact) the rate constants for a number of catalytic materials outline a volcano curve when plotted against their heats of oxygen chemisorption. However, the optima of the volcanoes correspond to different heats of chemisorption for the two contact situations. In both cases the activation...... oxidation. The optimum of the volcano curve in loose contact is estimated to occur between the bond strengths of α-Fe2O3 and α-Cr2O3. Guided by an interpolation principle FeaCrbOx binary oxides were tested, and the activity of these oxides was observed to pass through an optimum for an FeCr2Ox binary oxide...

  12. Catalytic and mechanistic insights of the low-temperature selective oxidation of methane over Cu-promoted Fe-ZSM-5.

    Science.gov (United States)

    Hammond, Ceri; Jenkins, Robert L; Dimitratos, Nikolaos; Lopez-Sanchez, Jose Antonio; ab Rahim, Mohd Hasbi; Forde, Michael M; Thetford, Adam; Murphy, Damien M; Hagen, Henk; Stangland, Eric E; Moulijn, Jacob M; Taylor, Stuart H; Willock, David J; Hutchings, Graham J

    2012-12-01

    The partial oxidation of methane to methanol presents one of the most challenging targets in catalysis. Although this is the focus of much research, until recently, approaches had proceeded at low catalytic rates (<10 h(-1)), not resulted in a closed catalytic cycle, or were unable to produce methanol with a reasonable selectivity. Recent research has demonstrated, however, that a system composed of an iron- and copper-containing zeolite is able to catalytically convert methane to methanol with turnover frequencies (TOFs) of over 14,000 h(-1) by using H(2)O(2) as terminal oxidant. However, the precise roles of the catalyst and the full mechanistic cycle remain unclear. We hereby report a systematic study of the kinetic parameters and mechanistic features of the process, and present a reaction network consisting of the activation of methane, the formation of an activated hydroperoxy species, and the by-production of hydroxyl radicals. The catalytic system in question results in a low-energy methane activation route, and allows selective C(1)-oxidation to proceed under intrinsically mild reaction conditions. PMID:23150452

  13. Heteropolymolybdate as a New Reaction-controlled Phase-transfer Catalyst for Efficient Alcohol Oxidation with Hydrogen Peroxide

    Institute of Scientific and Technical Information of China (English)

    Zhi Huan WENG; Jin Yan WANG; Xi Gao JIAN

    2006-01-01

    A new catalytic process for the synthesis of aldehyde from alcohol by oxidation with H2O2 with high selectivity was studied. In this system, heteropolymolybdate [C7H7N(CH3)3]3{PO4[MoO(O2)2]4} was utilized as the reaction-controlled phase-transfer catalyst to catalyze oxidation of benzyl and aliphatic alcohols. The molar ratio of H2O2 and alcohol was 0.75, no other by-products were detected by gas chromatography, the results of oxidation reaction indicated that the catalyst has high activity and stability.

  14. The variation of cationic microstructure in Mn-doped spinel ferrite during calcination and its effect on formaldehyde catalytic oxidation.

    Science.gov (United States)

    Liang, Xiaoliang; Liu, Peng; He, Hongping; Wei, Gaoling; Chen, Tianhu; Tan, Wei; Tan, Fuding; Zhu, Jianxi; Zhu, Runliang

    2016-04-01

    In this study, a series of Mn substituted spinel ferrites calcinated at different temperatures were used as catalysts for the oxidation of formaldehyde (HCHO). X-ray diffraction, Raman spectroscopy, X-ray photoelectron spectroscopy and H2 temperature-programmed reduction were conducted to characterize the structure and physico-chemical properties of catalysts, which were affected by calcination in the range of 200-600°C. Results show that all the ferrites were with spinel structure, and those calcinated in the range of 300-600°C were in the phase of maghemite. The calcination changed the valence and distribution of Mn and Fe on the ferrite surface, and accordingly the reducibility of ferrites. The HCHO catalytic oxidation test showed that with the increase of calcination temperature, the activity was initially improved until 400°C, but then decreased. The variation of HCHO conversion performance was well positively correlated to the variation of reduction temperature of surface Mn(4+) species. The remarkable effect of calcination on the catalytic activity of Mn-doped spinel ferrites for HCHO oxidation was discussed in view of reaction mechanism and variations in cationic microstructure of Mn-doped ferrites. PMID:26774985

  15. Catalytic wet oxidation of the pretreated synthetic pulp and paper mill effluent under moderate conditions.

    Science.gov (United States)

    Garg, Anurag; Mishra, I M; Chand, Shri

    2007-01-01

    In the present study, catalytic wet oxidation (CWO) was investigated for the destruction of organic pollutants in the thermally pretreated effluent from a pulp and paper mill under moderate temperature and pressure conditions. The thermal pretreatment studies were conducted at atmospheric pressure and 368K using copper sulfate as a catalyst. The thermal pretreatment reduced COD by about 61%. The filtrate of the thermal pretreatment step was used at pH 8.0 for CWO at 383-443K temperature and a total pressure of 0.85MPa for 4h. Catalysts used for the reaction include copper sulfate, 5% CuO/95% activated carbon, 60% CuO/40% MnO(2), and 60% CuO/40% CeO(2). Maximum COD reduction was found to be 89% during CWO step using 5% CuO/95% activated carbon with a catalyst loading of 8gl(-1) at 443K and 0.85MPa total pressure. Overall COD reduction for the pretreatment and the CWO was found to be 96%. Besides this, 60% CuO/40% CeO(2) catalyst also exhibited the similar activity as that of obtained with 5% CuO/95% activated carbon catalyst at 423K temperature and 0.85MPa total pressure. The pH of the solution during the experimental runs decreases initially due to the formation of carboxylic acid and then increases due to the decomposition of acids. PMID:16934854

  16. Catalytic oxidation at surfaces: insight from first-principles statistical mechanics (abstract only)

    Science.gov (United States)

    Rogal, Jutta

    2008-02-01

    Accomplishing a first-principles modeling of heterogeneous catalysis that allows for a quantitative description of the catalytic activity over a wide range of relevant environmental conditions (e.g. elevated temperatures and ambient pressures) poses an enormous challenge. Detailed insight into the elementary processes taking place on a microscopic level can nowadays often be obtained by employing ab initio electronic structure theory calculations. The statistical interplay between these processes, however, which is decisive for the functionality of a material only evolves in the mesoscopic to macroscopic regime. Here we apply a multiscale modeling approach to achieve a predictive modeling of macroscopic material properties on the basis of a microscopic understanding. Within this approach we use density-functional theory to accurately describe the elementary processes in the microscopic regime and we then combine these results with concepts from thermodynamics and statistical mechanics to obtain an appropriate linking to the mesoscopic and macroscopic regimes. Employing this approach to the field of heterogeneous catalysis we investigate CO oxidation over the Pd(100) surface as an example, particularly focusing on the relevance of the surrounding gas phase as well as the reaction kinetics on the structure and composition of the catalyst surface.

  17. Room-temperature solution synthesis of Ag nanoparticle functionalized molybdenum oxide nanowires and their catalytic applications

    International Nuclear Information System (INIS)

    A simple chemical solution route for the synthesis of large-scale high-quality Ag nanoparticle functionalized molybdenum oxide nanowire at room temperature has been developed. In the synthesis, the protonated amine was intercalated into the molybdenum bronze layers to reduce the electrostatic force of the lamellar structures, and then the Ag nanoparticle functionalized long nanowires could be easily induced by a redox reaction between a molybdenum oxide–amine intermediate and Ag+ at room temperature. The intercalation lamellar structures improved the nucleation and growth of the Ag nanoparticles, with the result that uniform Ag nanoparticles occurred on the surface of the MoO3 nanowire. In this way Ag nanoparticles with average sizes of around 6 nm, and high-purity nanowires with mean diameter of around 50 nm and with typical lengths of several tens to hundreds of micrometers were produced. The heteronanostructured nanowires were intricately and inseparably connected to each other with hydrogen bonds and/or bridge oxygen atoms and packed together, forming a paper-like porous network film. The Ag–MoO3 nanowire film performs a promoted catalytic property for the epoxidation of cis-cyclooctene, and the heteronanostructured nanowire film sensor shows excellent sensing performance to hydrogen and oxygen at room temperature. (paper)

  18. Transition-metal nitro-nitrosyl redox couple: catalytic oxidation of olefins to ketones

    International Nuclear Information System (INIS)

    A new nitroso-nitrosyl redox couple based on the readily prepared complex bis(acetonitrile)chloronitropalladium(II) is reported which catalytically air oxidizes olefines to ketones. Results of 18O labelling mechanistic studies are included, and spectroscopic evidence for an intermediate involved in oxygen-atom transfer by a nitro group is presented. The effects of olefin substituents were also investigated

  19. Catalytic Oxidation of Low Concentration Gaseous Organic Pollutants over Electrospun Nanofibrous Catalysts

    Czech Academy of Sciences Publication Activity Database

    Soukup, Karel; Topka, Pavel; Hejtmánek, Vladimír; Šolcová, Olga

    San Francisco : -, 2014, 40 /P062/. ISBN N. [International Conference on Electrospinning /3./. San Francisco (US), 04.08.2014-07.08.2014] R&D Projects: GA ČR(CZ) GAP204/11/1206 Institutional support: RVO:67985858 Keywords : electrospinning * electrospun nanofibrous catalyst * catalytic oxidation Subject RIV: CI - Industrial Chemistry, Chemical Engineering

  20. Catalytic Oxidation of Low Concentration Gaseous Organic Pollutants over Electrospun Nanofibrous Catalysts

    Czech Academy of Sciences Publication Activity Database

    Soukup, Karel; Topka, Pavel; Hejtmánek, Vladimír; Šolcová, Olga

    San Francisco: -, 2014, 40 /P062/. ISBN N. [International Conference on Electrospinning /3./. San Francisco (US), 04.08.2014-07.08.2014] R&D Projects: GA ČR(CZ) GAP204/11/1206 Institutional support: RVO:67985858 Keywords : electrospinning * electrospun nanofibrous catalyst * catalytic oxidation Subject RIV: CI - Industrial Chemistry, Chemical Engineering

  1. Pt and Au Nanostructured Materials for Catalytic Oxidation of Ethanol and Toluene

    Czech Academy of Sciences Publication Activity Database

    Gaálová, Jana; Kaluža, Luděk; Topka, Pavel

    2010, s. 409. ISBN N. [NANOSMAT-5. Remis (FR), 19.10.2010-21.10.2010] R&D Projects: GA ČR GPP106/10/P019 Institutional research plan: CEZ:AV0Z40720504 Keywords : catalytic oxidation * ethanol * toluene Subject RIV: CI - Industrial Chemistry, Chemical Engineering http://www.nanosmat-conference.com/

  2. Orange II removal by catalytic wet peroxide oxidation using activated carbon xerogels

    OpenAIRE

    Pinho, Maria; Silva, Adrián; Fathy, Nady; Attia, Amina; Gomes, Helder; Faria, Joaquim

    2013-01-01

    Orange II is a synthetic dye widely employed in the textile industry and responsible for serious environrnentaI cancerns. Dyes like this urge the development af new technologies for the treatment af wastewaters generated in this industrial activity. Those include catalytic wet peroxide oxidation (CWPO), which is an advanced oxidation process (AOP) based on the generation of hydroxyl radicais (I-lO·) from hydrogen peroxide with tlle aid ofa suitable catalysl [I].

  3. Bulk Preparation of Holey Graphene via Controlled Catalytic Oxidation

    Science.gov (United States)

    Watson, Kent (Inventor); Lin, Yi (Inventor); Ghose, Sayata (Inventor); Connell, John (Inventor)

    2015-01-01

    A scalable method allows preparation of bulk quantities of holey carbon allotropes with holes ranging from a few to over 100 nm in diameter. Carbon oxidation catalyst nanoparticles are first deposited onto a carbon allotrope surface in a facile, controllable, and solvent-free process. The catalyst-loaded carbons are then subjected to thermal treatment in air. The carbons in contact with the carbon oxidation catalyst nanoparticles are selectively oxidized into gaseous byproducts such as CO or CO.sub.2, leaving the surface with holes. The catalyst is then removed via refluxing in diluted nitric acid to obtain the final holey carbon allotropes. The average size of the holes correlates strongly with the size of the catalyst nanoparticles and is controlled by adjusting the catalyst precursor concentration. The temperature and time of the air oxidation step, and the catalyst removal treatment conditions, strongly affect the morphology of the holes.

  4. Integrated Biomass Gasification with Catalytic Partial Oxidation for Selective Tar Conversion

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Lingzhi; Wei, Wei; Manke, Jeff; Vazquez, Arturo; Thompson, Jeff; Thompson, Mark

    2011-05-28

    requirement for commercial deployment of biomass-based power/heat co-generation and biofuels production. There are several commonly used syngas clean-up technologies: (1) Syngas cooling and water scrubbing has been commercially proven but efficiency is low and it is only effective at small scales. This route is accompanied with troublesome wastewater treatment. (2) The tar filtration method requires frequent filter replacement and solid residue treatment, leading to high operation and capital costs. (3) Thermal destruction typically operates at temperatures higher than 1000oC. It has slow kinetics and potential soot formation issues. The system is expensive and materials are not reliable at high temperatures. (4) In-bed cracking catalysts show rapid deactivation, with durability to be demonstrated. (5) External catalytic cracking or steam reforming has low thermal efficiency and is faced with problematic catalyst coking. Under this program, catalytic partial oxidation (CPO) is being evaluated for syngas tar clean-up in biomass gasification. The CPO reaction is exothermic, implying that no external heat is needed and the system is of high thermal efficiency. CPO is capable of processing large gas volume, indicating a very compact catalyst bed and a low reactor cost. Instead of traditional physical removal of tar, the CPO concept converts tar into useful light gases (eg. CO, H2, CH4). This eliminates waste treatment and disposal requirements. All those advantages make the CPO catalytic tar conversion system a viable solution for biomass gasification downstream gas clean-up. This program was conducted from October 1 2008 to February 28 2011 and divided into five major tasks. - Task A: Perform conceptual design and conduct preliminary system and economic analysis (Q1 2009 ~ Q2 2009) - Task B: Biomass gasification tests, product characterization, and CPO tar conversion catalyst preparation. This task will be conducted after completing process design and system economics analysis

  5. The applicability of the catalytic wet-oxidation to CELSS

    Science.gov (United States)

    Takahashi, Y.; Nitta, K.; Ohya, H.; Oguchi, M.

    1987-01-01

    The wet oxidation catalysis of Au, Pd, Pt, Rh or Ru on a ceramic honeycomb carrier was traced in detail by 16 to 20 repetitive batch tests each. As a result, Pt or Pd on a honeycomb carrier was shown to catalyze complete nitrogen gasification as N2. Though the catalysts which realize both complete nitrogen gasification and complete oxidation could not be found, the Ru+Rh catalyst was found to be most promising. Ru honeycomb catalyzed both nitrification and nitrogen gasification.

  6. Selective catalytic reduction of nitric oxide with acetaldehyde over NaY zeolite catalyst in lean exhaust feed

    International Nuclear Information System (INIS)

    Steady-state selective catalytic reduction (SCR) of nitric oxide (NO) was investigated under simulated lean-burn conditions using acetaldehyde (CH3CHO) as the reductant. This work describes the influence of catalyst space velocity and the impact of nitric oxide, acetaldehyde, oxygen, sulfur dioxide, and water on NOx reduction activity over NaY zeolite catalyst. Results indicate that with sufficient catalyst volume 90% NOx conversion can be achieved at temperatures relevant to light-duty diesel exhaust (150-350C). Nitric oxide and acetaldehyde react to form N2, HCN, and CO2. Oxygen is necessary in the exhaust feed stream to oxidize NO to NO2 over the catalyst prior to reduction, and water is required to prevent catalyst deactivation. Under conditions of excess acetaldehyde (C1:N>6:1) and low temperature (x conversion is apparently very high; however, the NOx conversion steadily declines with time due to catalytic oxidation of some of the stored (adsorbed) NO to NO2, which can have a significant impact on steady-state NOx conversion. With 250ppm NO in the exhaust feed stream, maximum NOx conversion at 200C can be achieved with =400ppm of acetaldehyde, with higher acetaldehyde concentrations resulting in production of acetic acid and breakthrough of NO2 causing lower NOx conversion levels. Less acetaldehyde is necessary at lower NO concentrations, while more acetaldehyde is required at higher temperatures. Sulfur in the exhaust feed stream as SO2 can cause slow deactivation of the catalyst by poisoning the adsorption and subsequent reaction of nitric oxide and acetaldehyde, particularly at low temperature

  7. Preparation and characterization of Ce1-xFexO2 complex oxides and its catalytic activity for methane selective oxidation

    Institute of Scientific and Technical Information of China (English)

    LI Kongzhai; WANG Hua; WEI Yonggang; LIU Mingchun

    2008-01-01

    A series of Ce1-xFexO2 (x=0, 0.2, 0.4, 0.6, 0.8, 1) complex oxide catalysts were prepared using the coprecipitation method. The catalysts were characterized by means of XRD and H2-TPR. The reactions between methane and lattice oxygen from the complex oxides were investigated. The characteristic results revealed that the combination of Ce and Fe oxide in the catalysts could lower the temperature necessary to reduce the cerium oxide. The catalytic activity for selective CH4 oxidation was strongly influenced by dropped Fe species. Adding the appropriate amount of Fe2O3 to CeO2 could promote the action between CH4 and CeO2. Dispersed Fe2O3 first returned to the original state and would then virtually form the Fe species on the catalyst, which could be considered as the active site for selective CH4 oxidation. The appearance of carbon formation was significant and the oxidation of carbon appeared to be the rate-determining step; the amounts of surface reducible oxygen species in CeO2 were also relevant to the activity. Among all the catalysts, Ce0.6Fe0.4O2 exhibited the best activity, which converted 94.52% of CH4 at 900 °C.

  8. Treatment of phenol wastewater by microwave-induced ClO2-CuOx/Al2O3 catalytic oxidation process

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    The catalyst of CuOx/Al2O3 was prepared by the dipping-sedimentation method using γ-Al2O3 as a carrier. CuO and Cu2O were loaded on the surface of γ-Al2O3, characterized by X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS). In the presence of CuOx/Al2O3, the microwave-induced chlorine dioxide (ClO2) catalytic oxidation process was conducted for the treatment of synthetic wastewater containing 100 mg/L phenol. The relationships between removal percentage and initial ClO2 concentration, catalyst dosage, microwave power, contact time, initial phenol concentration and pH were investigated and the results showed that microwave-induced ClO2-CuOx/Al2O3 process could effectively degrade contaminants in a short reaction time with a low oxidant dosage, extensive pH range. Under a given condition (ClO2 concentration 80 mg/L, microwave power 50 W, contact time 5 min, catalyst dosage 50 g/L, pH 9), phenol removal percentage approached 92.24%, corresponding to 79.13% of CODCr removal. The removal of phenol by microwave-induced ClO2-CuOx/Al2O3 catalytic oxidation process was a complicated non-homogeneous solid/water reaction, which fitted pseudo-first-order by kinetics. Compared with traditional ClO2 oxidation, ClO2 catalytic oxidation and microwave-induced ClO2 oxidation, microwave-induced ClO2 catalytic oxidation system could significantly enhance the degradation efficiency. It provides an effective technology for the removal of phenol wastewater.

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

    Science.gov (United States)

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

    2016-01-01

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

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

    Science.gov (United States)

    Toyoshima, Ryo; Kondoh, Hiroshi

    2015-03-01

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

  11. Laccase-Functionalized Graphene Oxide Assemblies as Efficient Nanobiocatalysts for Oxidation Reactions

    NARCIS (Netherlands)

    Patila, Michaela; Kouloumpis, Antonios; Gournis, Dimitrios; Rudolf, Petra; Stamatis, Haralambos

    2016-01-01

    Multi-layer graphene oxide-enzyme nanoassemblies were prepared through the multi-point covalent immobilization of laccase from Trametes versicolor (TvL) on functionalized graphene oxide (fGO). The catalytic properties of the fGO-TvL nanoassemblies were found to depend on the number of the graphene o

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

    Science.gov (United States)

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

    2012-11-26

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

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

    Energy Technology Data Exchange (ETDEWEB)

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

    1998-07-01

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

  14. Removal of Selected Heavy Metals from Green Mussel via Catalytic Oxidation

    International Nuclear Information System (INIS)

    Perna viridis or green mussel is a potentially an important aquaculture product along the South Coast of Peninsular Malaysia especially Johor Straits. As the coastal population increases at tremendous rate, there was significant effect of land use changes on marine communities especially green mussel, as the heavy metals input to the coastal area also increase because of anthropogenic activities. Heavy metals content in the green mussel exceeded the Malaysian Food Regulations (1985) and EU Food Regulations (EC No: 1881/ 2006). Sampling was done at Johor Straits from Danga to Pendas coastal area for green mussel samples. This research introduces a catalytic oxidative technique for demetallisation in green mussel using edible oxidants such as peracetic acid (PAA) enhanced with alumina beads supported CuO, Fe2O3, and ZnO catalysts. The lethal dose of LD50 to rats of PAA is 1540 mg kg-1 was verified by National Institute of Safety and Health, United State of America. The best calcination temperature for the catalysts was at 1000 degree Celsius as shown in the X-Ray Diffraction (XRD), Nitrogen Adsorption (BET surface area) and Field Emission Scanning Electron Microscopy (FESEM) analyses. The demetallisation process in green mussel was done successfully using only 100 mgL-1 PAA and catalyzed with Fe2O3/ Al2O3 for up to 90 % mercury (Hg) removal. Using PAA with only 1 hour of reaction time, at room temperature (30-35 degree Celsius), pH 5-6 and salinity of 25-28 ppt, 90 % lead (Pb) was removed from life mussel without catalyst. These findings have a great prospect for developing an efficient and practical method for post-harvesting heavy metals removal in green mussel. (author)

  15. Effect of vegetable oil oxidation on the hydrogenation reaction process

    OpenAIRE

    Kalantari, Faranak; Bahmaei, Manochehr; Ameri, Majid; Shoaei, Ehsan

    2010-01-01

    Hydrogenation has been carried out in a batch reactor with three different oxidized bleached oils in order to discover the effect of oxidation on the hydrogenation reaction process. Specifications of hydrogenated oils such as melting point, Iodine value, solid fat content and fatty acid composition of the oxidized oils were compared with their un-oxidized reference oils. Oxidized bleached sunflower oil was hydrogenated to target melting points (34, 39 and 42°C) at higher iodine values vs. its...

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

    Science.gov (United States)

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

    2013-03-01

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

  17. A New Class of Highly Dispersed VOx Catalysts on Mesoporous Silica: Synthesis, Characterization, and Catalytic Activity in the Partial Oxidation of Ethanol

    Energy Technology Data Exchange (ETDEWEB)

    Kwak, Ja Hun; Herrera, Jose E.; Hu, Jian Zhi; Wang, Yong; Peden, Charles HF

    2006-01-26

    The morphology of vanadium oxide supported on a titania-modified mesoporous silica (MCM-41), obtained by means of a careful grafting process through atomic layer deposition, was studied using a variety of characterization techniques. The XRD together with TEM, 51V-NMR, Raman, FTIR and DRS-UV-Vis results showed that the vanadia species are extremely well dispersed onto the surface of the mesoporous support; the dispersion being stable upon thermal treatments up to 400 °C. Studies of the catalytic activity of these materials were performed using the partial oxidation of ethanol as a probe reaction. The results indicate an intrinsic relationship between dispersion, the presence of a TiO2-VOx phase, and catalytic activity for oxidation and dehydration.

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

    Science.gov (United States)

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

    2015-07-21

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

  19. Study of nano-structured ceria for catalytic CO oxidation

    Czech Academy of Sciences Publication Activity Database

    Valechha, D.; Lokhande, S.; Klementová, Mariana; Šubrt, Jan; Rayalu, S.; Labhsetwar, N.

    2011-01-01

    Roč. 21, č. 11 (2011), s. 3718-3725. ISSN 0959-9428 Institutional research plan: CEZ:AV0Z40320502 Keywords : mesoporous CeO2 * titania * alumina * oxides Subject RIV: CA - Inorganic Chemistry Impact factor: 5.968, year: 2011

  20. Tritiated water processing using liquid phase catalytic exchange and solid oxide electrolyte cell

    International Nuclear Information System (INIS)

    Liquid phase catalytic exchange (LPCE) is an effective method for enrichment and removal of tritium from tritiated water. Combined electrolysis catalytic exchange (CECE) process is an attractive application of a LPCE column. We proposed a new process that improves the CECE process. Using a solid oxide electrolyte (SOE) cell for electrolysis makes the CECE process more energy efficient and eliminates other disadvantages such as large tritium inventory and extremely slow system response. When the cell is used for recombination, the system becomes even more simple, efficiently, reliable and safe. 21 refs., 9 figs

  1. Modeling of adsorber/desorber/catalytic reactor system for ethylene oxide removal

    OpenAIRE

    ZELJKO B. GRBAVCIC; BOSKO V. GRBIC; ZORANA LJ. ARSENIJEVIC

    2004-01-01

    The removal of ethylene oxide (EtO) in a combined system adsorber/desorber/catalytic reactor has been investigated. The combined system was a modified draft tube spouted bed reactor loaded with Pt/Al2O3 catalyst. The annular region was divided into two sectons, the hot section contained about 7 % of catalyst and it behaved as a desorber and catalytic incinerator, while the cold section, with the rest of the catalyst, behaved as a sorber. The catalyst particles were circulated between the two ...

  2. Recombinant oxalate decarboxylase: enhancement of a hybrid catalytic cascade for the complete electro-oxidation of glycerol.

    Science.gov (United States)

    Abdellaoui, Sofiene; Hickey, David P; Stephens, Andrew R; Minteer, Shelley D

    2015-10-01

    The complete electro-oxidation of glycerol to CO2 is performed through an oxidation cascade using a hybrid catalytic system combining a recombinant enzyme, oxalate decarboxylase from Bacillus subtilis, and an organic oxidation catalyst, 4-amino-TEMPO. This system is capable of electrochemically oxidizing glycerol at a carbon electrode collecting all 14 electrons per molecule. PMID:26271633

  3. Selective Production of Aromatic Aldehydes from Heavy Fraction of Bio-oil via Catalytic Oxidation

    Energy Technology Data Exchange (ETDEWEB)

    Li, Yan; Chang, Jie; Ouyang, Yong; Zheng, Xianwei [South China Univ. of Technology, Guangzhou (China)

    2014-06-15

    High value-added aromatic aldehydes (e. g. vanillin and syringaldehyde) were produced from heavy fraction of bio-oil (HFBO) via catalytic oxidation. The concept is based on the use of metalloporphyin as catalyst and hydrogen peroxide (H{sub 2}O{sub 2}) as oxidant under alkaline condition. The biomimetic catalyst cobalt(II)-sulfonated tetraphenylporphyrin (Co(TPPS{sub 4})) was prepared and characterized. It exhibited relative high activity in the catalytic oxidation of HFBO. 4.57 wt % vanillin and 1.58 wt % syringaldehyde were obtained from catalytic oxidation of HFBO, compared to 2.6 wt % vanillin and 0.86 wt % syringaldehyde without Co(TPPS{sub 4}). Moreover, a possible mechanism of HFBO oxidation using Co(TPPS{sub 4})/H{sub 2}O{sub 2} was proposed by the research of model compounds. The results showed that this is a promising and environmentally friendly method for production of aromatic aldehydes from HFBO under Co(TPPS{sub 4})/H{sub 2}O{sub 2} system.

  4. Electro-catalytic oxidative cleavage of lignin in a protic ionic liquid.

    Science.gov (United States)

    Reichert, Elena; Wintringer, Reiner; Volmer, Dietrich A; Hempelmann, Rolf

    2012-04-21

    Lignin is a component of lignocellulosic biomass and a promising matrix for recovering important renewable aromatic compounds. We present a new approach of electro-oxidative cleavage of lignin, dissolved in a special protic ionic liquid, using an anode with particular electro-catalytic activity. As appropriate ionic liquid triethylammonium methanesulfonate was identified, synthesised, explored for dissolution of alkali-lignin and used for electrolysis of 5 wt.% lignin solutions. As appropriate anode material, oxidation-stable ruthenium-vanadium-titanium mixed oxide electrodes were prepared and explored for their electro-catalytic activity. The electrolysis was performed at several potentials in the range from 1.0 V to 1.5 V (vs. an Ag pseudo reference electrode). A wide range of aromatic fragments was identified as cleavage products by means of GC-MS and HPLC measurements. PMID:22398694

  5. Synthesis, characterization and catalytic activity toward methanol oxidation of electrocatalyst Pt4+-NH2-MCM-41

    International Nuclear Information System (INIS)

    Highlights: ► It was first confirmed that the Pt4+ exhibited a good electro-catalytic property for methanol oxidation. ► The Pt4+ perfectly distributed on a mesoporous molecular sieve matrix synthesis by a facile method. ► The good performance of catalyst resistance to poisoning because of a homogeneous distribution of Pt4+ and large specific surface area. - Abstract: Mesoporous material with functional group (Pt4+-NH2-MCM-41) was prepared by grafting aminopropyl group and adsorbing platinum ions on the surface of the commercial molecular sieve (MCM-41). The characterization carried out by X-ray photoelectron spectroscopy, X-ray diffraction, and N2 adsorption–desorption measurement pointed out that Pt was adsorbed on the NH2-MCM-41 surface as the oxidation state (Pt4+) and the surface area of Pt4+-NH2-MCM-41 was up to 564 m2/g. Transmission electron microscopy and elemental mapping indicated a homogeneous distribution of Pt4+ throughout all surface of the mesoporous materials. Electro-catalytic properties of methanol oxidation on the Pt4+-NH2-MCM-41 electrode were investigated with electrochemical methods. The results showed that the Pt4+-NH2-MCM-41 electrode exhibited catalytic activity in the methanol electro-oxidation with the apparent activation energy being 49.29 kJ/mol, and the control step of methanol electro-oxidation was the mass transfer process. It is first proved that platinum ions had good electro-catalytic property for methanol oxidation and provided a new idea for developing electrode materials in future.

  6. Catalytic Activity and Stability of Oxides: The Role of Near-Surface Atomic Structures and Compositions.

    Science.gov (United States)

    Feng, Zhenxing; Hong, Wesley T; Fong, Dillon D; Lee, Yueh-Lin; Yacoby, Yizhak; Morgan, Dane; Shao-Horn, Yang

    2016-05-17

    Electrocatalysts play an important role in catalyzing the kinetics for oxygen reduction and oxygen evolution reactions for many air-based energy storage and conversion devices, such as metal-air batteries and fuel cells. Although noble metals have been extensively used as electrocatalysts, their limited natural abundance and high costs have motivated the search for more cost-effective catalysts. Oxides are suitable candidates since they are relatively inexpensive and have shown reasonably high activity for various electrochemical reactions. However, a lack of fundamental understanding of the reaction mechanisms has been a major hurdle toward improving electrocatalytic activity. Detailed studies of the oxide surface atomic structure and chemistry (e.g., cation migration) can provide much needed insights for the design of highly efficient and stable oxide electrocatalysts. In this Account, we focus on recent advances in characterizing strontium (Sr) cation segregation and enrichment near the surface of Sr-substituted perovskite oxides under different operating conditions (e.g., high temperature, applied potential), as well as their influence on the surface oxygen exchange kinetics at elevated temperatures. We contrast Sr segregation, which is associated with Sr redistribution in the crystal lattice near the surface, with Sr enrichment, which involves Sr redistribution via the formation of secondary phases. The newly developed coherent Bragg rod analysis (COBRA) and energy-modulated differential COBRA are uniquely powerful ways of providing information about surface and interfacial cation segregation at the atomic scale for these thin film electrocatalysts. In situ ambient pressure X-ray photoelectron spectroscopy (APXPS) studies under electrochemical operating conditions give additional insights into cation migration. Direct COBRA and APXPS evidence for surface Sr segregation was found for La1-xSrxCoO3-δ and (La1-ySry)2CoO4±δ/La1-xSrxCoO3-δ oxide thin films, and

  7. Physicochemical and catalytic properties of vanadium molybdenum oxide catalyst prepared from vanadyl oxalate

    International Nuclear Information System (INIS)

    The formation of the phase composition, porous structure and catalytic properties of vanadium molybdenum oxide catalyst prepared by sputtered drying of the ammonium paramolybdate and banadyl oxalate with subsequent thermal treatment in the air flow is considered. Comparative study of catalyst properties depending on chemical nature of the initial vanadium compound-vanadyl oxalate and ammonium metavanadate is carried out. It is shown that VMo3O11 compound formation at air flow thermal treatment in a rather broad temperature range (300-400 deg) makes preferable using vanadyl oxalate as compared with ammonium metavanadate for the synthesis of massive vanadium molybdenum oxide catalysts of partial acrolein oxidation to acrylic acid

  8. An Overview of Recent Advances of the Catalytic Selective Oxidation of Ethane to Oxygenates

    Directory of Open Access Journals (Sweden)

    Robert D. Armstrong

    2016-05-01

    Full Text Available The selective partial oxidation of short chain alkanes is a key challenge within catalysis research. Direct ethane oxidation to oxygenates is a difficult aim, but potentially rewarding, and it could lead to a paradigm shift in the supply chain of several bulk chemicals. Unfortunately, low C–H bond reactivity and kinetically labile products are just some reasons affecting the development and commercialisation of such processes. Research into direct ethane oxidation is therefore disparate, with approaches ranging from oxidation in the gas phase at high temperatures to enzyme catalysed hydroxylation under ambient conditions. Furthermore, in overcoming the barrier posed by the chemically inert C–H bond a range of oxidants have been utilised. Despite years of research, this remains an intriguing topic from both academic and commercial perspectives. Herein we describe some recent developments within the field of catalytic ethane oxidation focusing on the formation of oxygenated products, whilst addressing the key challenges which are still to be overcome.

  9. Catalytic Enhancement of Solid Carbon Oxidation in HDCFCs

    DEFF Research Database (Denmark)

    Deleebeeck, Lisa; Ippolito, Davide; Kammer Hansen, Kent

    2014-01-01

    was investigated using current-potential-power density curves. In the anode chamber, catalysts are mixed with the carbon-carbonate mixture. These catalysts include various manganese oxides (MnO2, Mn2O3, and Mn3O4) and dopedceria (CeO2, Ce1-xGdxO2-x/2, Ce1-xRExO2-delta (RE = Pr, Sm)), the effectiveness...

  10. The catalytic oxidation of manganese in water treatment clarification processes

    OpenAIRE

    Lloyd, A.

    1982-01-01

    The removal of dissolved manganese in water treatment floc blanket clarifiers has been studied. The removal mechanisms may be broadly classed as adsorption and oxidation. Adsorption of manganese (II) occurs rapidly and is completed in less than five minutes under conditions prevailing in a floe blanket clarifier. The extent of adsorption is determined by pH, iron and manganese concentrations. Manganese adsorption is relatively insensitive to the concentration of other cations and anions prese...

  11. Removal of formaldehyde over Mn(x)Ce(1)-(x)O(2) catalysts: thermal catalytic oxidation versus ozone catalytic oxidation.

    Science.gov (United States)

    Li, Jia Wei; Pan, Kuan Lun; Yu, Sheng Jen; Yan, Shaw Yi; Chang, Moo Been

    2014-12-01

    Mn(x)Ce(1)-(x)O(2) (x: 0.3-0.9) prepared by Pechini method was used as a catalyst for the thermal catalytic oxidation of formaldehyde (HCHO). At x=0.3 and 0.5, most of the manganese was incorporated in the fluorite structure of CeO(2) to form a solid solution. The catalytic activity was best at x=0.5, at which the temperature of 100% removal rate is the lowest (270°C). The temperature for 100% removal of HCHO oxidation is reduced by approximately 40°C by loading 5wt.% CuO(x) into Mn(0.5)Ce(0.5)O(2). With ozone catalytic oxidation, HCHO (61 ppm) in gas stream was completely oxidized by adding 506 ppm O₃over Mn(0.5)Ce(0.5)O(2) catalyst with a GHSV (gas hourly space velocity) of 10,000 hr⁻¹ at 25°C. The effect of the molar ratio of O(3) to HCHO was also investigated. As O(3)/HCHO ratio was increased from 3 to 8, the removal efficiency of HCHO was increased from 83.3% to 100%. With O(3)/HCHO ratio of 8, the mineralization efficiency of HCHO to CO(2) was 86.1%. At 25°C, the p-type oxide semiconductor (Mn(0.5)Ce(0.5)O(2)) exhibited an excellent ozone decomposition efficiency of 99.2%, which significantly exceeded that of n-type oxide semiconductors such as TiO(2), which had a low ozone decomposition efficiency (9.81%). At a GHSV of 10,000 hr⁻¹, [O(3)]/[HCHO]=3 and temperature of 25°C, a high HCHO removal efficiency (≥ 81.2%) was maintained throughout the durability test of 80 hr, indicating the long-term stability of the catalyst for HCHO removal. PMID:25499503

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

    International Nuclear Information System (INIS)

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

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

    Energy Technology Data Exchange (ETDEWEB)

    Carrado, K.A.

    1986-01-01

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

  14. Thermal behavior and catalytic activity in naphthalene destruction of Ce-, Zr- and Mn-containing oxide layers on titanium

    International Nuclear Information System (INIS)

    The present paper is devoted to studies of the composition and surface structure, including those after annealing at high temperatures, and catalytic activity in the reaction of naphthalene destruction of Ce-, Zr- and Mn-containing oxide layers on titanium obtained by means of the plasma electrolytic oxidation (PEO) method. The composition and structure of the obtained systems were investigated using the methods of X-ray phase and energy dispersive analysis and scanning electron microscopy (SEM). It was demonstrated that Ce- and Zr- containing structures had relatively high thermal stability: their element and phase compositions and surface structure underwent virtually no changes after annealing in the temperature range 600-800 deg. C. Annealing of Ce- and Zr-containing coatings in the temperature range 850-900 deg. C resulted in substantial changes of their surface composition and structure: a relatively homogeneous and porous surface becomes coated by large pole-like crystals. The catalytic studies showed rather high activity of Ce- and Zr-containing coatings in the reaction of naphthalene destruction at temperatures up to 850 deg. C. Mn-containing structures of the type MnOx + SiO2 + TiO2/Ti have a well-developed surface coated by 'nano-whiskers'. The phase composition and surface structure of manganese-containing layers changes dramatically in the course of thermal treatment. After annealing above 600 deg. C nano-whiskers vanish with formation of molten structures on the surface. The Mn-containing oxide systems demonstrated lower conversion degrees than the Ce- and Zr-containing coatings, which can be attributed to substantial surface modification and formation of molten manganese silicates at high temperatures.

  15. Reaction-transport simulations of non-oxidative methane conversion with continuous hydrogen removal: Homogeneous-heterogeneous methane reaction pathways

    International Nuclear Information System (INIS)

    Detailed kinetic-transport models were used to explore thermodynamic and kinetic barriers in the non-oxidative conversion of CH4 via homogeneous and homogeneous-heterogeneous pathways and the effects of continuous hydrogen removal and of catalytic sites on attainable yields of useful C2-C10 products. The homogeneous kinetic model combines separately developed models for low-conversion pyrolysis and for chain growth to form large aromatics and carbon. The H2 formed in the reaction decreases CH4 pyrolysis rates and equilibrium conversions and it favors the formation of lighter products. The removal of H2 along tubular reactors with permeable walls increases reaction rates and equilibrium CH4 conversions. C2-C10 yields reach values greater than 90 percent at intermediate values of dimensionless transport rates (delta=1-10), defined as the ratio hydrogen transport and methane conversion rates. Homogeneous reactions require impractical residence times, even with H2 removal, because of slow initiation and chain transfer rates. The introduction of heterogeneous chain initiation pathways using surface sites that form methyl radicals eliminates the induction period without influencing the homogeneous product distribution. Methane conversion, however, occurs predominately in the chain transfer regime, within which individual transfer steps and the formation of C2 intermediates become limited by thermodynamic constraints. Catalytic sites alone cannot overcome these constraints. Catalytic membrane reactors with continuous H2 removal remove these thermodynamic obstacles and decrease the required residence time. Reaction rates become limited by homogeneous reactions of C2 products to form C6+ aromatics. Higher delta values lead to subsequent conversion of the desired C2-C10 products to larger polynuclear aromatics. We conclude that catalytic methane pyrolysis at the low temperatures required for restricted chain growth and the elimination of thermodynamics constraints via

  16. Preparation and Catalytic Activity for Aerobic Glucose Oxidation of Crown Jewel Structured Pt/Au Bimetallic Nanoclusters

    Science.gov (United States)

    Zhang, Haijun; Wang, Liqiong; Lu, Lilin; Toshima, Naoki

    2016-08-01

    Understanding of the “structure-activity” relations for catalysts at an atomic level has been regarded as one of the most important objectives in catalysis studies. Bimetallic nanoclusters (NCs) in its many types, such as core/shell, random alloy, cluster-in-cluster, bi-hemisphere, and crown jewel (one kind of atom locating at the top position of another kind of NC), attract significant attention owing to their excellent optical, electronic, and catalytic properties. PVP-protected crown jewel-structured Pt/Au (CJ-Pt/Au) bimetallic nanoclusters (BNCs) with Au atoms located at active top sites were synthesized via a replacement reaction using 1.4-nm Pt NCs as mother clusters even considering the fact that the replacement reaction between Pt and Au3+ ions is difficult to be occurred. The prepared CJ-Pt/Au colloidal catalysts characterized by UV-Vis, TEM, HR-TEM and HAADF-STEM-EELS showed a high catalytic activity for aerobic glucose oxidation, and the top Au atoms decorating the Pt NCs were about 15 times more active than the Au atoms of Au NCs with similar particle size.

  17. In situ growth of hollow CuNi alloy nanoparticles on reduced graphene oxide nanosheets and their magnetic and catalytic properties

    International Nuclear Information System (INIS)

    Highlights: • RGO–CuNi nanocomposite was synthesized by a facile one-pot co-reduction process. • Hollow CuNi nanocrystals were uniformly deposited on RGO sheets. • Possible formation mechanism of the hollow CuNi nanocrystals is proposed. • RGO–CuNi exhibits excellent catalytic performance toward the oxidation of glucose. • RGO–CuNi shows superior catalytic activity toward the reduction of 4-NP by NaBH4. - Abstract: Hollow CuNi nanocrystals supported on reduced graphene oxide (RGO–CuNi) are synthesized by in situ co-reduction of Cu2+, Ni2+ and graphene oxide (GO) in a one-pot reaction. The as-synthesized RGO–CuNi nanocomposites were characterized by X-ray diffraction, transmission electron microscopy, energy-dispersive X-ray spectrometry, inductively coupled plasma optical emission spectrometry, Raman spectroscopy, and magnetic measurement. It is revealed that hollow CuNi nanocrystals with an average size of about 35.1 nm are uniformly deposited on the surface of RGO nanosheets. The formation mechanism of the hollow CuNi nanostructures is also proposed based on the galvanic displacement reaction. The as-synthesized RGO–CuNi nanocomposite exhibits excellent electrocatalytic performance toward the oxidation of glucose in alkaline media, and also shows superior catalytic activity and recycling stability toward the reduction of 4-nitrophenol (4-NP) to 4-aminophenol (4-AP). Moreover, the RGO–CuNi catalysts can be easily recollected from the reaction system by an external magnetic field due to their considerable saturation magnetization. It is anticipated that loading hollow nanostructures on RGO sheets would open up a new avenue for developing multifunctional catalysts with low cost and high catalytic performance

  18. In situ growth of hollow CuNi alloy nanoparticles on reduced graphene oxide nanosheets and their magnetic and catalytic properties

    Energy Technology Data Exchange (ETDEWEB)

    Yang, Jinglei [School of Chemistry and Chemical Engineering, Jiangsu University, Zhenjiang 212013 (China); Shen, Xiaoping, E-mail: xiaopingshen@163.com [School of Chemistry and Chemical Engineering, Jiangsu University, Zhenjiang 212013 (China); Ji, Zhenyuan [School of Materials Science and Engineering, Jiangsu University, Zhenjiang 212013 (China); Zhou, Hu [School of Material Science and Engineering, Jiangsu University of Science and Technology, Zhenjiang 212003 (China); Zhu, Guoxing [School of Chemistry and Chemical Engineering, Jiangsu University, Zhenjiang 212013 (China); Chen, Kangmin [School of Materials Science and Engineering, Jiangsu University, Zhenjiang 212013 (China)

    2014-10-15

    Highlights: • RGO–CuNi nanocomposite was synthesized by a facile one-pot co-reduction process. • Hollow CuNi nanocrystals were uniformly deposited on RGO sheets. • Possible formation mechanism of the hollow CuNi nanocrystals is proposed. • RGO–CuNi exhibits excellent catalytic performance toward the oxidation of glucose. • RGO–CuNi shows superior catalytic activity toward the reduction of 4-NP by NaBH{sub 4}. - Abstract: Hollow CuNi nanocrystals supported on reduced graphene oxide (RGO–CuNi) are synthesized by in situ co-reduction of Cu{sup 2+}, Ni{sup 2+} and graphene oxide (GO) in a one-pot reaction. The as-synthesized RGO–CuNi nanocomposites were characterized by X-ray diffraction, transmission electron microscopy, energy-dispersive X-ray spectrometry, inductively coupled plasma optical emission spectrometry, Raman spectroscopy, and magnetic measurement. It is revealed that hollow CuNi nanocrystals with an average size of about 35.1 nm are uniformly deposited on the surface of RGO nanosheets. The formation mechanism of the hollow CuNi nanostructures is also proposed based on the galvanic displacement reaction. The as-synthesized RGO–CuNi nanocomposite exhibits excellent electrocatalytic performance toward the oxidation of glucose in alkaline media, and also shows superior catalytic activity and recycling stability toward the reduction of 4-nitrophenol (4-NP) to 4-aminophenol (4-AP). Moreover, the RGO–CuNi catalysts can be easily recollected from the reaction system by an external magnetic field due to their considerable saturation magnetization. It is anticipated that loading hollow nanostructures on RGO sheets would open up a new avenue for developing multifunctional catalysts with low cost and high catalytic performance.

  19. Catalytic ozonation of oxalate with a cerium supported palladium oxide: An efficient degradation not relying on hydroxyl radical oxidation

    KAUST Repository

    Zhang, Tao

    2011-11-01

    The cerium supported palladium oxide (PdO/CeO 2) at a low palladium loading was found very effective in catalytic ozonation of oxalate, a probe compound that is difficult to be efficiently degraded in water with hydroxyl radical oxidation and one of the major byproducts in ozonation of organic matter. The oxalate was degraded into CO 2 during the catalytic ozonation. The molar ratio of oxalate degraded to ozone consumption increased with increasing catalyst dose and decreasing ozone dosage and pH under the conditions of this study. The maximum molar ratio reached around 1, meaning that the catalyst was highly active and selective for oxalate degradation in water. The catalytic ozonation, which showed relatively stable activity, does not promote hydroxyl radical generation from ozone. Analysis with ATR-FTIR and in situ Raman spectroscopy revealed that 1) oxalate was adsorbed on CeO 2 of the catalyst forming surface complexes, and 2) O 3 was adsorbed on PdO of the catalyst and further decomposed to surface atomic oxygen (*O), surface peroxide (*O 2), and O 2 gas in sequence. The results indicate that the high activity of the catalyst is related to the synergetic function of PdO and CeO 2 in that the surface atomic oxygen readily reacts with the surface cerium-oxalate complex. This kind of catalytic ozonation would be potentially effective for the degradation of polar refractory organic pollutants and hydrophilic natural organic matter. © 2011 American Chemical Society.

  20. Catalytic wet peroxide oxidation of aniline in wastewater using copper modified SBA-15 as catalyst.

    Science.gov (United States)

    Kong, Liming; Zhou, Xiang; Yao, Yuan; Jian, Panming; Diao, Guowang

    2016-01-01

    SBA-15 mesoporous molecular sieves modified with copper (Cu-SBA-15) were prepared by pH-adjusting hydrothermal method and characterized by X-ray diffraction, BET, transmission electron microscopy, UV-Vis and (29)Si MAS NMR. The pH of the synthesis gel has a significant effect on the amount and the dispersion of copper on SBA-15. The Cu-SBA-15(4.5) (where 4.5 denotes the pH value of the synthesis gel) modified with highly dispersed copper was used as catalyst for the oxidation of aniline by H2O2. The Cu-SBA-15(4.5) shows a higher catalytic activity compared to CuO on the surface of SBA-15. The influences of reaction conditions, such as initial pH of the aqueous solutions, temperature, as well as the dosages of H2O2 and catalyst were investigated. Under weakly alkaline aqueous solution conditions, the aniline conversion, the H2O2 decomposition and the total organic carbon (TOC) removal could be increased significantly compared to the acid conditions. The percentage of leaching Cu(2+) could be decreased from 45.0% to 3.66% when the initial pH of solution was increased from 5 to 10. The TOC removal could be enhanced with the increases of temperature, H2O2 and catalyst dosage, but the aniline conversion and H2O2 decomposition change slightly with further increasing dosage of catalyst and H2O2. At 343 K and pH 8.0, 100% aniline conversion and 66.9% TOC removal can be achieved under the conditions of 1.0 g/L catalyst and 0.05 mol/L H2O2 after 180 min. Although copper might be slightly leached from catalyst, the homogeneous Cu(2+) contribution to the whole catalytic activity is unimportant, and the highly dispersed copper on SBA-15 plays a dominant role. PMID:26227827

  1. Catalytic Enhancement of Solid Carbon Oxidation in HDCFCs

    DEFF Research Database (Denmark)

    Deleebeeck, Lisa; Ippolito, Davide; Kammer Hansen, Kent

    2014-01-01

    Hybrid direct carbon fuel cells (HDCFCs) consisting of a solid carbon (carbon black)-molten carbonate ((62-38 wt% Li-K)2CO3) mixtures in the anode chamber of an anode-supported solid oxide fuel cell (SOFC)-type full-cell (NiO-yttria-stablized zirconia (YSZ)|YSZ|lanthanum strontium manganite (LSM...... in the carbon-carbonate mixture in the anode chamber of an HDCFC. 96-4 vol% N2-CO2 (anode), air (cathode), 755°C, 0-600 mA, 50 mA/step. Power density corrected to cathode geometric surface area. [Formula]...... impedance data as a function of temperature, anode and cathode atmospheres, and their flow rates are discussed. In the anode chamber, catalysts are mixed with the carbon-carbonate mixture. These catalysts include various manganese oxides (MnO2, Mn2O3, and Mn3O4, Fig. 1) and doped-ceria (CeO2, Ce1-xGdxO2, Ce...

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

    International Nuclear Information System (INIS)

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

  3. Synergy of CuO and CeO2 combination for mercury oxidation under low-temperature selective catalytic reduction atmosphere

    KAUST Repository

    Li, Hailong

    2016-07-19

    Synergy for low temperature Hg0 oxidation under selective catalytic reduction (SCR) atmosphere was achieved when copper oxides and cerium oxides were combined in a CuO-CeO2/TiO2 (CuCeTi) catalyst. Hg0 oxidation efficiency as high as 99.0% was observed on the CuCeTi catalyst at 200 °C, even the gas hourly space velocity was extremely high. To analyze the synergistic effect, comparisons of catalyst performance in the presence of different SCR reaction gases were systematically conducted over CuO/TiO2 (CuTi), CeO2/TiO2 (CeTi) and CuCeTi catalysts prepared by sol-gel method. The interactions between copper oxides and cerium oxides in CuCeTi catalyst yielded more surface chemisorbed oxygen, and facilitated the conversion of gas-phase O2 to surface oxygen, which are favorable for Hg0 oxidation. Copper oxides in the combination interacted with NO forming more chemisorbed oxygen for Hg0 oxidation in the absence of gas-phase O2. Cerium oxides in the combination promoted Hg0 oxidation through enhancing the transformations of NO to NO2. In the absence of NO, NH3 exhibited no inhibitive effect on Hg0 oxidation, because enough Lewis acid sites due to the combination of copper oxides and cerium oxides scavenged the competitive adsorption between NH3 and Hg0. In the presence of NO, although NH3 lowered Hg0 oxidation rate through inducing reduction of oxidized mercury, complete recovery of Hg0 oxidation activity over the CuCeTi catalyst was quickly achieved after cutting off NH3. This study revealed the synergistic effect of the combination of copper oxides and cerium oxides on Hg0 oxidation, and explored the involved mechanisms. Such knowledge would help obtaining maximum Hg0 oxidation co-benefit from SCR units in coal-fired power plants.

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

    Science.gov (United States)

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

    2015-01-01

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

  5. CATALYTIC WET PEROXIDE OXIDATION OF HYDROQUINONE WITH Co(II)/ACTIVE CARBON CATALYST LOADED IN STATIC BED

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    Catalysts based on Co(II) supported on active carbon were prepared and loaded in static bed. The hydroquinone would be degraded completely after treated by Catalytic wet peroxide oxidation method with Co(II)/active carbon catalyst. After activate treatment, the active carbon was immerged in cobaltous nitrate solution, then put into a drying oven, Co(II) could be loaded on the micro-surface of carbon. Taking the static bed as the equipment, the absorption of active carbon and catalysis of Co(II) was used to reduce activation energy of hydroquinone. Thus hydroquinone could be drastically degraded and the effluent can be drained under the standard. Referring to Fenton reaction mechanism, experiment had been done to study the heterogeneous catalyzed oxidation mechanism of Co(II). The degradation rate of hydroquinone effluent could be achieved to 92% when treated in four columns at H2O2 concentration 10%, reaction temperature 40℃ , pH 5 and reaction time 2.5h.

  6. CATALYTIC WET PEROXIDE OXIDATION OF HYDROQUINONE WITH Co(Ⅱ)/ACTIVE CARBON CATALYST LOADED IN STATIC BED

    Institute of Scientific and Technical Information of China (English)

    LI Chunxiang; YAN Yongsheng; XU Wanzhen

    2008-01-01

    Catalysts based on Co(Ⅱ) supported on active carbon were prepared and loaded in static bed.The hydroquinone wouid be degraded completely after treated by Catalytic wet peroxide oxidation method with Co(Ⅱ)/active carbon catalyst.After activate treatment, the active carbon was immerged in cobaltoas nitrate solution, then put into a drying oven, Co(Ⅱ) could be loaded on the micro-surface of carbon.Taking the static bed as the equipment, the absorption of active carbon and catalysis of Co(Ⅱ) was used to reduce activation energy of hydroquinone.Thus hydroquinone could be drastically degraded and the effluent can be drained under the standard.Referring to Fenton reaction mechanism, experiment had been done to study the heterogeneous catalyzed oxidation mechanism of Co(Ⅱ).The degradation rate of hydroquinone effluent could be achieved to 92% when treated in four columns at H2O2 concentration 10%, reaction temperature 40℃, pH 5 and reaction time 2.5h.

  7. Influence of physicochemical treatments on spent palladium based catalyst for catalytic oxidation of VOCs

    International Nuclear Information System (INIS)

    To recycle the spent catalyst for the removal of VOCs, the benzene, toluene, and xylene (BTX) complete oxidations were studied over pretreated palladium based spent catalyst in a fixed bed flow reactor system at atmospheric pressure. Two different pretreatment methods with gas (air and hydrogen) and acid aqueous solution (HCl, H2SO4, HNO3, H3PO4 and CH3COOH) were used to investigate the catalytic activity of spent catalyst. The properties of the spent and pretreated Pd based catalyst were characterized by XRD, BET, TEM, ICP, and XPS. The results of light-off curves indicate that the catalytic activity of toluene oxidation for pretreated samples is in the order of hydrogen > air > HNO3 > CH3COOH > H2SO4 > H3PO4 > HCl. In addition, the air and the acid aqueous pretreated catalyst activities were significantly decreased compared to that of the spent (or parent) catalyst. Moreover, hydrogen pretreated (or reduced) catalysts having mainly metallic form show the best performance in removing the toluene vapours compared to other pretreated samples. The reduction temperature made a significant difference in the catalytic performance of the spent catalyst pretreated with hydrogen. XPS results clearly supported that the palladium state of the spent catalysts pretreated at 300 deg. C was shifted more toward metallic form than other reduced catalysts. Furthermore, the results of a long-term test and catalytic activity of aromatic hydrocarbons also supported that the hydrogen pretreated spent catalyst was a good candidate for removing toxic compounds

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

    Indian Academy of Sciences (India)

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

    2015-06-01

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

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

    Science.gov (United States)

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

    2015-12-23

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

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

    Directory of Open Access Journals (Sweden)

    Matthieu Jouffroy

    2014-10-01

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

  11. Sonochemically synthesized mono and bimetallic Au-Ag reduced graphene oxide based nanocomposites with enhanced catalytic activity.

    Science.gov (United States)

    Neppolian, Bernaurdshaw; Wang, Chang; Ashokkumar, Muthupandian

    2014-11-01

    Graphene oxide (GO) supported Ag and Au mono-metallic and Au-Ag bimetallic catalysts were synthesized using a sonochemical method. Bimetallic catalysts containing different weight ratios of Au and Ag were loaded onto GO utilizing a low frequency horn-type ultrasonicator. High frequency ultrasonication was used to efficiently reduce Ag(I) and Au(III) ions in the presence of polyethylene glycol and 2-propanol. Transmission electron microscopy (TEM-EDX) and X-ray photoelectron spectroscopy were used to analyze the morphology, size, shape and chemical oxidation states of the prepared metallic catalysts on GO. The catalytic efficiency of the prepared catalysts were compared using 4-nitrophenol (4-NP) reduction reaction and the subsequent formation of 4-aminophenol (4-AP) that was also monitored using UV-vis spectrophotometry. The results revealed that Au-Ag-GO bimetallic catalysts showed high activity for the conversion of 4-NP to 4-AP than their monometallic counterparts. Amongst different weight ratios (1:1, 1:2 and 2:1) between Au and Ag, the 1:2 (Au:Ag) catalyst exhibited very good catalytic performance for the conversion of 4-NP to 4-AP. A total reduction of 4-NP took place within a short period of time if Au-GO was reduced first followed by Ag reduction, whereas a lower reduction rate was observed if Ag-GO was reduced first. The same trend was observed for all the ratios of bimetallic catalysts prepared by this method. The initial unfavorable reduction potential of Ag(I) is likely to be responsible for the above order. It was found that applying dual frequency ultrasonication was a highly effective way of preparing bimetallic catalysts requiring relatively low levels of added chemicals and producing bimetallic catalysts with GO with improved catalytic efficiency. PMID:24582660

  12. 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

    -Mead method of nonlinear regression. On the basis of the obtained results of characterization process and conducted catalytic tests, the following can be observed. Zeolite structure of the prepared catalyst was confirmed through powder X-ray diffraction, scanning electron microscopy and adsorption techniques. Their catalytic performance was monitored in terms of phenol and total organic carbon (TOC conversions, hydrogen peroxide decomposition, by-product distribution and degree of copper leached into the aqueous solution. The obtained experimental results indicate that in the space of 180 minutes, the use of these catalysts allows almost total elimination of phenol and significant removal of total organic carbon content with the use of small amounts of catalyst (0.1 g dm–3 and substoichiometric level (71.4 % of oxidant required for complete oxidation of organic pollutant. The main product among aromatics was catechol, followed by hydroquinone and benzoquinone, which exhibited the typical pattern for a series reaction scheme. The distribution of carboxylic acids was as follows: maleic, fumaric, acetic and oxalic acids. These low-molecular carboxylic acids and aromatic compounds were responsible for the TOC that remained after almost complete removal of phenol. Moreover, one of the most interesting options was to use CWPO as a pre-treatment prior to biological treatment, for simple organic acids that are highly biodegradable. During the reactions, destabilization of the catalyst was observed in terms of leaching of copper from zeolite into the reaction mixture, but the previous investigations of similar catalytic systems showed that the activity of the solid catalyst was not due to the homogeneous contribution of the copper leached from the catalyst, but was more likely due to the activity of the heterogeneous catalyst. Further investigations on the mechanism of catalyst destabilization and methods of stabilization are the subject of the following article in the series. The

  13. Benzyl alcohol oxidation in supercritical carbon dioxide: spectroscopic insight into phase behaviour and reaction mechanism.

    Science.gov (United States)

    Caravati, Matteo; Grunwaldt, Jan-Dierk; Baiker, Alfons

    2005-01-21

    Selective oxidation of benzyl alcohol to benzaldehyde with molecular oxygen over an alumina-supported palladium catalyst was performed with high rate at about 95% selectivity in supercritical carbon dioxide. The experiments in a continuous flow fixed-bed reactor showed that the pressure has a strong influence on the reaction rate. A marked increase of the rate (turnover frequency) from 900 h(-1) to 1800 h(-1) was observed when increasing the pressure from 140 to 150 bar. Video monitoring of the bulk fluid phase behavior and the simultaneous investigation by transmission and attenuated total reflection (ATR) infrared spectroscopy at two positions of the view cell showed that the sharp increase in activity is correlated to a transition from a biphasic to a monophasic reaction mixture. In the single phase region, both oxygen and benzyl alcohol are dissolved in the supercritical CO2 phase, which leads to a reduction of the mass transport resistances (both in the external fluid film and in the catalyst pores) and thus to the high reaction rate measured in the catalytic experiments. The phase transition could be effectively and easily monitored by transmission and ATR-IR spectroscopy despite the small concentration of the dense liquid like phase. Deposition of the Pd/Al2O3 catalyst on the ATR-crystal at the bottom of the view cell allowed to gain insight into the chemical changes and mass transfer processes occurring in the solid/liquid interface region during reaction. Analyzing the shift of the upsilon2 bending mode of CO2 gave information on the fluid composition in and outside the catalyst pores. Moreover, the catalytic reaction could be investigated in situ in this spectroscopic batch reactor cell by monitoring simultaneously the reaction progress, the phase behaviour and the catalytic interface. PMID:19785149

  14. Microwave-enhanced catalytic degradation of 4-chlorophenol over nickel oxides under low temperature

    International Nuclear Information System (INIS)

    Microwave-enhance catalytic degradation (MECD) of 4-chlorophenol (4-CP) using nickel oxide was studied. A mix-valenced nickel oxide was obtained from nickel nitrate aqueous solution through a precipitation with sodium hydroxide and an oxidation by sodium hypochlorite (assigned as PO). Then, the as-prepared PO was irradiated under microwave irradiation to fabricate a high active mix-valenced nickel oxide (assigned as POM). Further, pure nanosized nickel oxide was obtained from the POM by calcination at 300, 400 and 500 deg. C (labeled as C300, C400 and C500, respectively). They were characterized by X-ray (XRD), infrared spectroscopy (IR) and temperature-programmed reduction (TPR). Their catalytic activities towards the degradation of 4-CP on the efficiency of the degradation were further investigated under continuous bubbling of air through the liquid-phase and quantitative evaluation by high pressure liquid chromatography (HPLC). Also, the effects of temperature, pH and kinds of catalysts on the efficiency of the degradation have been investigated. The results showed that the 4-CP was degraded completely by MECD method within 20 min under pH 7, T = 40 deg. C and C = 200 g dm-3 over POM catalyst. The relative activity was affected significantly with the oxidation state of nickel

  15. Preparation of Molecular Sieve Catalyst and Application in the Catalytic Oxidation Treatment of Waste Water

    Institute of Scientific and Technical Information of China (English)

    WANG; RongMin

    2001-01-01

    Citric acid is an important additive in foods, cosmetics, medicine and so on, but it discharges about 10 ton of factory effluent when 1 ton of citric acid is produced. The COD of the factory effluent is near 20000 mg/L. The treatment of citric acid factory effluent is a serious problem in environmental chemistry.  It is found that molecular sieve support metal complexes have high catalytic activity in aerobic oxidation of alkene [1,2]. In this paper, a kind of molecular sieve catalyst was prepared. The catalyst was used for the treatment of citric acid factory effluent by method of catalytic oxygen oxidation.  ……

  16. Influence of catalyst pretreatments on the catalytic oxidation of toluene over nanostructured platinum based spent catalyst.

    Science.gov (United States)

    Shim, Wang-Geun; Lee, Jae-Wook; Kim, Sang-Chai

    2007-11-01

    In this study, we regenerated a nano-structured platinum based spent catalyst by applying thermal gas and acid pretreatment and examined the influence of treatment on the catalytic oxidation of toluene. The spent catalysts were pretreated with air, hydrogen and six different acid aqueous solutions (HCl, H2SO4, HNO3, H3PO4, CH3COOH and C2H2O4). The physicochemical properties of the parent and its modified catalysts were characterized by XRD, BET, TEM, and ICP. The results of light-off curves showed that air and hydrogen treated catalysts were more active than the parent catalyst. In addition, the catalytic activities of toluene oxidation for acid aqueous treated samples were identical with the order of Pt/Al ratio. PMID:18047055

  17. Optical and electro-catalytic studies of nanostructured thulium oxide for vitamin C detection

    Energy Technology Data Exchange (ETDEWEB)

    Singh, Jay [Department of BIN Fusion Technology, Chonbuk National University, Jeonju, Jeonbuk 561-756 (Korea, Republic of); Department of Polymer-Nano Science and Technology, Chonbuk National University, Jeonju, Jeonbuk 561-756 (Korea, Republic of); Srivastava, Manish [Department of Physics, Dehradun Institute of Technology (DIT), School of Engineering, Greater Noida 201308 (India); Roychoudhury, Appan [Department of Biotechnology, Delhi Technological University, Shahbad Daulatpur, Main Bawana Road, Delhi 110 042 (India); Lee, Dong Won [Department of BIN Fusion Technology, Chonbuk National University, Jeonju, Jeonbuk 561-756 (Korea, Republic of); Department of Polymer-Nano Science and Technology, Chonbuk National University, Jeonju, Jeonbuk 561-756 (Korea, Republic of); Lee, Seung Hee, E-mail: lsh1@jbnu.ac.kr [Department of BIN Fusion Technology, Chonbuk National University, Jeonju, Jeonbuk 561-756 (Korea, Republic of); Department of Polymer-Nano Science and Technology, Chonbuk National University, Jeonju, Jeonbuk 561-756 (Korea, Republic of); Malhotra, B.D., E-mail: bansi.malhotra@gmail.com [Department of Biotechnology, Delhi Technological University, Shahbad Daulatpur, Main Bawana Road, Delhi 110 042 (India); Department of Science and Technology Centre on Biomolecular Electronics, Biomedical Instrumentation Section, Material Physics and Engineering Division, CSIR-National Physical Laboratory, Dr. K.S. Krishnan Marg, New Delhi 110 012 (India); Center for NanoBioengineering and Spintronics, Chungnam National University, 220 Gung-Dong, Yuseong-Gu, Daejeon 305-764 (Korea, Republic of)

    2013-11-25

    Highlights: •Nanostructured thulium oxide has been prepared using the hydrothermal process. •Thulium oxide exhibits excellent electrochemical response towards ascorbic acid. •Thulium oxide is interesting electro-optical material. •Rare earth metal oxide offers potential application biosensing and optoelectronics. -- Abstract: In this report, the nanostructured thulium oxide (Tm{sub 2}O{sub 3}) has been prepared using the hydrothermal process without using any template and further heat treatment. The crystalline structure and morphology of prepared sample have been determined by X-ray diffraction (XRD), field-emission scanning electron microscopy (FE-SEM), transmission electron microscopy (TEM), atomic force microscopy (AFM) and Fourier transform infrared (FTIR) spectroscopic techniques. The optical properties of prepared sample have been examined by ultra-violet (UV–Vis), photoluminescence (PL), Raman and X-ray photoelectron spectroscopy (XPS) studies. Furthermore, Tm{sub 2}O{sub 3} nanoparticles have been electrophoretically deposited (EPD) onto indium–tin–oxide (ITO) glass substrate and utilized for electro-oxidation of ascorbic acid (AA). The electro-catalytic behavior of Tm{sub 2}O{sub 3}/ITO and bare ITO electrodes for AA electro-oxidation has been studied by cyclic voltammetry. Catalytic oxidation peak current shows a linear dependence on the AA concentration and a linear calibration curve is obtained in the concentration range of 0.2–8 mM of AA. The obtained results indicate that the nanostructured Tm{sub 2}O{sub 3} based electrode offers an efficient strategy and a new promising platform for application of the rare earth metal oxide material in electrochemistry and bioelectronics.

  18. Green oxidations: Titanium dioxide induced tandem oxidation coupling reactions

    OpenAIRE

    Vineet Jeena; Robinson, Ross S.

    2009-01-01

    The application of titanium dioxide as an oxidant in tandem oxidation type processes is described. Under microwave irradiation, quinoxalines have been synthesized in good yields from the corresponding α-hydroxyketones.

  19. Innovative Catalysis in Organic Synthesis Oxidation, Hydrogenation, and C-X Bond Forming Reactions

    CERN Document Server

    Andersson, Pher G

    2012-01-01

    Authored by a European team of leaders in the field, this book compiles innovative approaches for C-X bond forming processes frequently applied in organic synthesis. It covers all key types of catalysis, including homogeneous, heterogeneous, and organocatalysis, as well as mechanistic and computational studies. Special attention is focused on the improvement of efficiency and sustainability of important catalytic processes, such as selective oxidations, hydrogenation and cross-coupling reactions.The result is a valuable resource for both advanced researchers in academia and industry, as well a

  20. Stability and catalytic performance of vanadia supported on nanostructured titania catalyst in oxidative dehydrogenation of propane

    International Nuclear Information System (INIS)

    Highlights: • Vanadia supported on titanate nanotube shows enhanced dispersion of vanadia. • Deactivatoin during propane ODH related to the rutile development. • Titanate nanotube transfers to anatase due to calcinations and presence of vanadia. - Abstract: Titanate nanotubes with a high specific surface area were synthesized by the simple hydrothermal method and investigated as support for V2O5 catalyst in oxidative dehydrogenation of propane (ODP). The structures of pristine nanotubes as well as the prepared catalysts were investigated by XRD, Raman, FTIR, HRTEM, SEM, EDS, BET, and XPS techniques. The characterization of the as-synthesized nanotubes showed the synthesis of hydrogen titanate nanotube. The incipient wetness impregnation method was utilized to prepare VTNT-x (x = 5, 10, and 15 wt.% vanadia supported on nanotube) together with VTi5 (5 wt.% vanadia supported on Degussa P25). The anatase phase was developed in VTNT-x catalysts upon calcination along with specific surface area loss. Higher vanadia loading resulted in the lowering of support capacity in maintaining vanadia in dispersed state such that eventually crystalline vanadia appeared. The measured catalyst activity demonstrates that in spite of major support surface area loss in VTNT-5 catalyst, the propylene yield is superior in comparison with VTi5 catalyst. The catalyst activity can be correlated with maximum reduction temperature. Deactivation of VTi5 and VTNT-5 as well as VTNT-15 were studied for 3,000 min time-on-stream. It was found that the activity of VTNT-5 catalyst remain unchanged while a decline in catalytic activity observed in VTi5 and VTNT-15 catalysts. The development of rutile was considered as being a major element in the deactivation of the investigated catalysts which is influenced by the presence of vanadium and reaction atmosphere