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Sample records for low-temperature methanol synthesis

  1. Process assessment of small scale low temperature methanol synthesis

    Energy Technology Data Exchange (ETDEWEB)

    Hendriyana [Chemical Engineering Department, Faculty of Engineering, Jenderal Achmad Yani Univerity (Indonesia); Chemical Engineering Department, Faculty of Industrial Technology, InstitutTeknologi Bandung (Indonesia); Susanto, Herri, E-mail: herri@che.itb.ac.id; Subagjo [Chemical Engineering Department, Faculty of Industrial Technology, InstitutTeknologi Bandung (Indonesia)

    2015-12-29

    Biomass is a renewable energy resource and has the potential to make a significant impact on domestic fuel supplies. Biomass can be converted to fuel like methanol via several step process. The process can be split into following main steps: biomass preparation, gasification, gas cooling and cleaning, gas shift and methanol synthesis. Untill now these configuration still has a problem like high production cost, catalyst deactivation, economy of scale and a huge energy requirements. These problems become the leading inhibition for biomass conversion to methanol, which should be resolved to move towards the economical. To address these issues, we developed various process and new configurations for methanol synthesis via methyl formate. This configuration combining two reactors: the one reactor for the carbonylation of methanol and CO to form methyl formate, and the second for the hydrogenolysis of methyl formate and H{sub 2} to form two molecule of methanol. Four plant process configurations were compared with the biomass basis is 300 ton/day. The first configuration (A) is equipped with a steam reforming process for converting methane to CO and H{sub 2} for increasing H{sub 2}/CO ratio. CO{sub 2} removal is necessary to avoid poisoning the catalyst. COSORB process used for the purpose of increasing the partial pressure of CO in the feed gas. The steam reforming process in B configuration is not used with the aim of reducing the number of process equipment, so expect lower investment costs. For C configuration, the steam reforming process and COSORB are not used with the aim of reducing the number of process equipment, so expect lower investment costs. D configuration is almost similar to the configuration A. This configuration difference is in the synthesis of methanol which was held in a single reactor. Carbonylation and hydrogenolysis reactions carried out in the same reactor one. These processes were analyzed in term of technical process, material and energy

  2. Process assessment of small scale low temperature methanol synthesis

    International Nuclear Information System (INIS)

    Hendriyana; Susanto, Herri; Subagjo

    2015-01-01

    Biomass is a renewable energy resource and has the potential to make a significant impact on domestic fuel supplies. Biomass can be converted to fuel like methanol via several step process. The process can be split into following main steps: biomass preparation, gasification, gas cooling and cleaning, gas shift and methanol synthesis. Untill now these configuration still has a problem like high production cost, catalyst deactivation, economy of scale and a huge energy requirements. These problems become the leading inhibition for biomass conversion to methanol, which should be resolved to move towards the economical. To address these issues, we developed various process and new configurations for methanol synthesis via methyl formate. This configuration combining two reactors: the one reactor for the carbonylation of methanol and CO to form methyl formate, and the second for the hydrogenolysis of methyl formate and H 2 to form two molecule of methanol. Four plant process configurations were compared with the biomass basis is 300 ton/day. The first configuration (A) is equipped with a steam reforming process for converting methane to CO and H 2 for increasing H 2 /CO ratio. CO 2 removal is necessary to avoid poisoning the catalyst. COSORB process used for the purpose of increasing the partial pressure of CO in the feed gas. The steam reforming process in B configuration is not used with the aim of reducing the number of process equipment, so expect lower investment costs. For C configuration, the steam reforming process and COSORB are not used with the aim of reducing the number of process equipment, so expect lower investment costs. D configuration is almost similar to the configuration A. This configuration difference is in the synthesis of methanol which was held in a single reactor. Carbonylation and hydrogenolysis reactions carried out in the same reactor one. These processes were analyzed in term of technical process, material and energy balance and economic

  3. The Role of Solvent Polarity on Low-Temperature Methanol Synthesis Catalyzed by Cu Nanoparticles

    Energy Technology Data Exchange (ETDEWEB)

    Ahoba-Sam, Christian [Department of Process, Energy and Environmental Technology, University College of Southeast Norway, Porsgrunn (Norway); Olsbye, Unni [Department of Chemistry, University of Oslo, Oslo (Norway); Jens, Klaus-Joachim, E-mail: Klaus.J.Jens@usn.no [Department of Process, Energy and Environmental Technology, University College of Southeast Norway, Porsgrunn (Norway)

    2017-07-14

    Methanol syntheses at low temperature in a liquid medium present an opportunity for full syngas conversion per pass. The aim of this work was to study the role of solvents polarity on low-temperature methanol synthesis reaction using eight different aprotic polar solvents. A “once through” catalytic system, which is composed of Cu nanoparticles and sodium methoxide, was used for methanol synthesis at 100°C and 20 bar syngas pressure. Solvent polarity rather than the 7–10 nm Cu (and 30 nm Cu on SiO{sub 2}) catalyst used dictated trend of syngas conversion. Diglyme with a dielectric constant (ε) = 7.2 gave the highest syngas conversion among the eight different solvents used. Methanol formation decreased with either increasing or decreasing solvent ε value of diglyme (ε = 7.2). To probe the observed trend, possible side reactions of methyl formate (MF), the main intermediate in the process, were studied. MF was observed to undergo two main reactions; (i) decarbonylation to form CO and MeOH and (ii) a nucleophilic substitution to form dimethyl ether and sodium formate. Decreasing polarity favored the decarbonylation side reaction while increasing polarity favored the nucleophilic substitution reaction. In conclusion, our results show that moderate polarity solvents, e.g., diglyme, favor MF hydrogenolysis and, hence, methanol formation, by retarding the other two possible side reactions.

  4. Surface-Bound Intermediates in Low-Temperature Methanol Synthesis on Copper. Participants and Spectators

    Energy Technology Data Exchange (ETDEWEB)

    Yang, Yong; Mei, Donghai; Peden, Charles HF; Campbell, Charles T.; Mims, Charles A.

    2015-11-03

    The reactivity of surface adsorbed species present on copper catalysts during methanol synthesis at low temperatures was studied by simultaneous infrared spectroscopy (IR) and mass spectroscopy (MS) measurements during “titration” (transient surface reaction) experiments with isotopic tracing. The results show that adsorbed formate is a major bystander species present on the surface under steady-state methanol synthesis reaction conditions, but it cannot be converted to methanol by reaction with pure H2, nor with H2 plus added water. Formate-containing surface adlayers for these experiments were produced during steady state catalysis in (a) H2:CO2 (with substantial formate coverage) and (b) moist H2:CO (with no IR visible formate species). Both these reaction conditions produce methanol at steady state with relatively high rates. Adlayers containing formate were also produced by (c) formic acid adsorption. Various "titration" gases were used to probe these adlayers at modest temperatures (T = 410-450K) and 6 bar total pressure. Methanol gas (up to ~1% monolayer equivalent) was produced in "titration" from the H2:CO2 catalytic adlayers by H2 plus water, but not by dry hydrogen. The decay in the formate IR features accelerated in the presence of added water vapor. The H2:CO:H2O catalytic adlayer produced similar methanol titration yields in H2 plus water but showed no surface formate features in IR (less than 0.2% monolayer coverage). Finally, formate from formic acid chemisorption produced no methanol under any titration conditions. Even under (H2:CO2) catalytic reaction conditions, isotope tracing showed that pre-adsorbed formate from formic acid did not contribute to the methanol produced. Although non-formate intermediates exist during low temperature methanol synthesis on copper which can be converted to methanol gas

  5. Obtaining low temperature catalysts for methanol synthesis by no-waste process

    Energy Technology Data Exchange (ETDEWEB)

    Il' ko, E G; Sushchaya, L E; Bondar' , P G

    1982-11-01

    Low temperature production of catalysts for methanol synthesis involves considerable pollution of the environment as well as formation of side products. The authors propose producing such catalysts from joint precipitates of copper and zinc carbonates includiing stabilizers produced by decomposing solvents, then drying, aging and shaping. This method avoids waste water usually formed in scrubbing to remove ions of alkaline metals. Aluminum hydroxide is suggested as a stabilizer. The catalyst tablets prepared in this way were found to have activity like those produced by other methods, and were suitable for industrial use.

  6. Origin of low temperature deactivation of Ni5Ga3 nanoparticles as catalyst for methanol synthesis

    DEFF Research Database (Denmark)

    Gardini, Diego; Sharafutdinov, Irek; Damsgaard, Christian Danvad

    that the highest methanol yield is obtained with a Ni5Ga3 alloy exposed to a 25% CO2 – 75% H2 reaction mixture at 210 °C [2]. Under these experimental conditions, the catalyst is found to lose 35% of its activity after 20 hours of continuous testing at both 1 and 5 Bars. Although in situ XRD and EXAFS studies [3......In an effort to find alternative energy sources capable to compete with fossil fuels, methanol synthesis could represent a realistic solution to store “green” hydrogen produced from electrolysis or photo-induced water splitting. Recently, density functional theory (DFT) calculations [1] proposed Ni......-Ga alloys as active catalysts for methanol production from syngas mixtures and Ni-Ga nanoparticles supported on highly porous silica have been prepared using an incipient wetness impregnation technique from a solution of nickel and gallium nitrates [2]. Tests conducted in a fixed-bed reactor showed...

  7. Ammonia synthesis at low temperatures

    DEFF Research Database (Denmark)

    Rod, Thomas Holm; Logadottir, Ashildur; Nørskov, Jens Kehlet

    2000-01-01

    have been carried out to evaluate its feasibility. The calculations suggest that it might be possible to catalytically produce ammonia from molecular nitrogen at low temperatures and pressures, in particular if energy is fed into the process electrochemically. (C) 2000 American Institute of Physics.......Density functional theory (DFT) calculations of reaction paths and energies for the industrial and the biological catalytic ammonia synthesis processes are compared. The industrial catalyst is modeled by a ruthenium surface, while the active part of the enzyme is modeled by a MoFe6S9 complex...

  8. Integrated methanol synthesis

    International Nuclear Information System (INIS)

    Jaeger, W.

    1982-01-01

    This invention concerns a plant for methanol manufacture from gasified coal, particularly using nuclear power. In order to reduce the cost of the hydrogen circuits, the methanol synthesis is integrated in the coal gasification plant. The coal used is gasified with hydration by means of hydrogen and the crude gas emerging, after cooling and separating the carbon dioxide and hydrogen sulphide, is mixed with the synthetic gas leaving the methane cracking furnace. This mixture is taken to the methanol synthesis and more than 90% is converted into methanol in one pass. The gas mixture remaning after condensation and separation of methanol is decomposed into three fractions in low temperature gas decomposition with a high proportion of unconverted carbon monoxide. The flow of methane is taken to the cracking furnace with steam, the flow of hydrogen is taken to the hydrating coal gasifier, and the flow of carbon monoxide is taken to the methanol synthesis. The heat required for cracking the methane can either be provided by a nuclear reactor or by the coke left after hydrating gasification. (orig./RB) [de

  9. Low Temperature Synthesis of Magnesium Aluminate Spinel

    International Nuclear Information System (INIS)

    Lebedovskaya, E.G.; Gabelkov, S.V.; Litvinenko, L.M.; Logvinkov, D.S.; Mironova, A.G.; Odejchuk, M.A.; Poltavtsev, N.S.; Tarasov, R.V.

    2006-01-01

    The low-temperature synthesis of magnesium-aluminum spinel is carried out by a method of thermal decomposition in combined precipitated hydrates. The fine material of magnesium-aluminium spinel with average size of coherent dispersion's area 4...5 nanometers is obtained. Magnesium-aluminum spinel and initial hydrates were investigated by methods of the differential thermal analysis, the x-ray phase analysis and measurements of weight loss during the dehydration and thermal decomposition. It is established that synthesis of magnesium-aluminum spinel occurs at temperature 300 degree C by method of the x-ray phase analysis

  10. Manufacturing Demonstration Facility: Low Temperature Materials Synthesis

    International Nuclear Information System (INIS)

    Graham, David E.; Moon, Ji-Won; Armstrong, Beth L.; Datskos, Panos G.; Duty, Chad E.; Gresback, Ryan; Ivanov, Ilia N.; Jacobs, Christopher B.; Jellison, Gerald Earle; Jang, Gyoung Gug; Joshi, Pooran C.; Jung, Hyunsung; Meyer, Harry M.; Phelps, Tommy

    2015-01-01

    The Manufacturing Demonstration Facility (MDF) low temperature materials synthesis project was established to demonstrate a scalable and sustainable process to produce nanoparticles (NPs) for advanced manufacturing. Previous methods to chemically synthesize NPs typically required expensive, high-purity inorganic chemical reagents, organic solvents and high temperatures. These processes were typically applied at small laboratory scales at yields sufficient for NP characterization, but insufficient to support roll-to-roll processing efforts or device fabrication. The new NanoFermentation processes described here operated at a low temperature (~60 C) in low-cost, aqueous media using bacteria that produce extracellular NPs with controlled size and elemental stoichiometry. Up-scaling activities successfully demonstrated high NP yields and quality in a 900-L pilot-scale reactor, establishing this NanoFermentation process as a competitive biomanufacturing strategy to produce NPs for advanced manufacturing of power electronics, solid-state lighting and sensors.

  11. Manufacturing Demonstration Facility: Low Temperature Materials Synthesis

    Energy Technology Data Exchange (ETDEWEB)

    Graham, David E. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Moon, Ji-Won [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Armstrong, Beth L. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Datskos, Panos G. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Duty, Chad E. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Gresback, Ryan [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Ivanov, Ilia N. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Jacobs, Christopher B. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Jellison, Gerald Earle [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Jang, Gyoung Gug [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Joshi, Pooran C. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Jung, Hyunsung [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Meyer, III, Harry M. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Phelps, Tommy [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)

    2015-06-30

    The Manufacturing Demonstration Facility (MDF) low temperature materials synthesis project was established to demonstrate a scalable and sustainable process to produce nanoparticles (NPs) for advanced manufacturing. Previous methods to chemically synthesize NPs typically required expensive, high-purity inorganic chemical reagents, organic solvents and high temperatures. These processes were typically applied at small laboratory scales at yields sufficient for NP characterization, but insufficient to support roll-to-roll processing efforts or device fabrication. The new NanoFermentation processes described here operated at a low temperature (~60 C) in low-cost, aqueous media using bacteria that produce extracellular NPs with controlled size and elemental stoichiometry. Up-scaling activities successfully demonstrated high NP yields and quality in a 900-L pilot-scale reactor, establishing this NanoFermentation process as a competitive biomanufacturing strategy to produce NPs for advanced manufacturing of power electronics, solid-state lighting and sensors.

  12. Investigations into low pressure methanol synthesis

    DEFF Research Database (Denmark)

    Sharafutdinov, Irek

    The central topic of this work has been synthesis, characterization and optimization of novel Ni-Ga based catalysts for hydrogenation of CO2 to methanol. The overall goal was to search for materials that could be used as a low temperature (and low pressure) methanol synthesis catalyst....... This is required for small scale delocalized methanol production sites, where installation of energy demanding compression units should be avoided. The work was triggered by DFT calculations, which showed that certain bimetallic systems are active towards methanol synthesis from CO2 and H2 at ambient pressure...... containing 5:3 molar ratio of Ni:Ga, the intrinsic activity (methanol production rate per active surface area) is comparable to that of highly optimised Cu/ZnO/Al2O3. Formation of the catalyst was investigated with the aid of in-situ XRD and in-situ XAS techniques. The mechanism of alloying was proposed...

  13. Low methanol permeable composite Nafion/silica/PWA membranes for low temperature direct methanol fuel cells

    International Nuclear Information System (INIS)

    Xu Weilin; Lu Tianhong; Liu Changpeng; Xing Wei

    2005-01-01

    Nafion/silica/phosphotungstic acid (PWA) composite membranes were studied for low temperature ( max = 70 mW/cm 2 ) than those of commercial Nafion without treatment (OCV = 0.68 V, P max = 62 mW/cm 2 ) at 80 deg. C

  14. Methanol induces low temperature resilient methanogens and improves methane generation from domestic wastewater at low to moderate temperatures.

    Science.gov (United States)

    Saha, Shaswati; Badhe, Neha; De Vrieze, Jo; Biswas, Rima; Nandy, Tapas

    2015-01-01

    Low temperature (methanol is a preferred substrate by methanogens in cold habitats. The study hypothesizes that methanol can induce the growth of low-temperature resilient, methanol utilizing, hydrogenotrophs in UASB reactor. The hypothesis was tested in field conditions to evaluate the impact of seasonal temperature variations on methane yield in the presence and absence of methanol. Results show that 0.04% (v/v) methanol increased methane up to 15 times and its effect was more pronounced at lower temperatures. The qPCR analysis showed the presence of Methanobacteriales along with Methanosetaceae in large numbers. This indicates methanol induced the growth of both the hydrogenotrophic and acetoclastic groups through direct and indirect routes, respectively. This study thus demonstrated that methanol can impart resistance in methanogenic biomass to low temperature and can improve performance of UASB reactor. Copyright © 2015 Elsevier Ltd. All rights reserved.

  15. Methanol synthesis beyond chemical equilibrium

    NARCIS (Netherlands)

    van Bennekom, J. G.; Venderbosch, R. H.; Winkelman, J. G. M.; Wilbers, E.; Assink, D.; Lemmens, K. P. J.; Heeres, H. J.

    2013-01-01

    In commercial methanol production from syngas, the conversion is thermodynamically limited to 0.3-0.7 leading to large recycles of non-converted syngas. This problem can be overcome to a significant extent by in situ condensation of methanol during its synthesis which is possible nowadays due to the

  16. Solution-phase synthesis of nanomaterials at low temperature

    Science.gov (United States)

    Zhu, Yongchun; Qian, Yitai

    2009-01-01

    This paper reviews the solution-phase synthesis of nanoparticles via some routes at low temperatures, such as room temperature route, wave-assisted synthesis (γ-irradiation route and sonochemical route), directly heating at low temperatures, and hydrothermal/solvothermal methods. A number of strategies were developed to control the shape, the size, as well as the dispersion of nanostructures. Using diethylamine or n-butylamine as solvent, semiconductor nanorods were yielded. By the hydrothermal treatment of amorphous colloids, Bi2S3 nanorods and Se nanowires were obtained. CdS nanowires were prepared in the presence of polyacrylamide. ZnS nanowires were obtained using liquid crystal. The polymer poly (vinyl acetate) tubule acted as both nanoreactor and template for the CdSe nanowire growth. Assisted by the surfactant of sodium dodecyl benzenesulfonate (SDBS), nickel nanobelts were synthesized. In addition, Ag nanowires, Te nanotubes and ZnO nanorod arrays could be prepared without adding any additives or templates.

  17. Low-Temperature Synthesis Routes to Intermetallic Superconductors

    Energy Technology Data Exchange (ETDEWEB)

    Schaak, Raymond E

    2008-01-08

    Over the past few years, our group has gained expertise at developing low-temperature solution-based synthetic pathways to complex nanoscale solids, with particular emphasis on nanocrystalline intermetallic compounds. Our synthetic capabilities are providing tools to reproducibly generate intermetallic nanostructures with simultaneous control over crystal structure, composition, and morphology. This DOE-funded project aims to expand these capabilities to intermetallic superconductors. This could represent an important addition to the tools that are available for the synthesis and processing of intermetallic superconductors, which traditionally utilize high-temperature, high-pressure, thin film, or gas-phase vacuum deposition methods. Our current knowledge of intermetallic superconductors suggests that significant enhancements could result from the inherent benefits of low-temperature solution synthesis, e.g. metastable phase formation, control over nanoscale morphology to facilitate size-dependent property studies, robust and inexpensive processability, low-temperature annealing and consolidation, and impurity incorporation (for doping, stoichiometry control, flux pinning, and improving the critical fields). Our focus is on understanding the superconducting properties as a function of synthetic route, crystal structure, crystallite size, and morphology, and developing the synthetic tools necessary to accomplish this. This research program can currently be divided into two classes of superconducting materials: intermetallics (transition metal/post transition metal) and metal carbides/borides. Both involve the development and exploitation of low-temperature synthesis routes followed by detailed characterization of structures and properties, with the goal of understanding how the synthetic pathways influence key superconducting properties of selected target materials. Because of the low-temperature methods used to synthesize them and the nanocrystalline morphologies

  18. Low-temperature synthesis of silicon carbide powder using shungite

    International Nuclear Information System (INIS)

    Gubernat, A.; Pichor, W.; Lach, R.; Zientara, D.; Sitarz, M.; Springwald, M.

    2017-01-01

    The paper presents the results of investigation the novel and simple method of synthesis of silicon carbide. As raw material for synthesis was used shungite, natural mineral rich in carbon and silica. The synthesis of SiC is possible in relatively low temperature in range 1500–1600°C. It is worth emphasising that compared to the most popular method of SiC synthesis (Acheson method where the temperature of synthesis is about 2500°C) the proposed method is much more effective. The basic properties of products obtained from different form of shungite and in wide range of synthesis temperature were investigated. The process of silicon carbide formation was proposed and discussed. In the case of synthesis SiC from powder of raw materials the product is also in powder form and not requires any additional process (crushing, milling, etc.). Obtained products are pure and after grain classification may be used as abrasive and polishing powders. (Author)

  19. Low-temperature synthesis of silicon carbide powder using shungite

    Energy Technology Data Exchange (ETDEWEB)

    Gubernat, A.; Pichor, W.; Lach, R.; Zientara, D.; Sitarz, M.; Springwald, M.

    2017-07-01

    The paper presents the results of investigation the novel and simple method of synthesis of silicon carbide. As raw material for synthesis was used shungite, natural mineral rich in carbon and silica. The synthesis of SiC is possible in relatively low temperature in range 1500–1600°C. It is worth emphasising that compared to the most popular method of SiC synthesis (Acheson method where the temperature of synthesis is about 2500°C) the proposed method is much more effective. The basic properties of products obtained from different form of shungite and in wide range of synthesis temperature were investigated. The process of silicon carbide formation was proposed and discussed. In the case of synthesis SiC from powder of raw materials the product is also in powder form and not requires any additional process (crushing, milling, etc.). Obtained products are pure and after grain classification may be used as abrasive and polishing powders. (Author)

  20. Low temperature synthesis of InP nanocrystals

    Energy Technology Data Exchange (ETDEWEB)

    Ung Thi Dieu Thuy [Institute of Materials Science (IMS), Vietnamese Academy of Science and Technology (VAST), 18 Hoang Quoc Viet, Cau Giay, Hanoi (Viet Nam); Tran Thi Thuong Huyen [Institute of Materials Science (IMS), Vietnamese Academy of Science and Technology (VAST), 18 Hoang Quoc Viet, Cau Giay, Hanoi (Viet Nam); National University of Thai Nguyen, 2 Luong Ngoc Quyen, Thai Nguyen (Viet Nam); Nguyen Quang Liem [Institute of Materials Science (IMS), Vietnamese Academy of Science and Technology (VAST), 18 Hoang Quoc Viet, Cau Giay, Hanoi (Viet Nam)], E-mail: liemnq@ims.vast.ac.vn; Reiss, Peter [DSM/INAC/SPrAM, UMR 5819 CEA-CNRS-Universite Joseph Fourier/LEMOH, CEA Grenoble, 17 rue des Martyrs, 38054 Grenoble Cedex 9 (France)

    2008-12-20

    We present a simple method for the chemical synthesis of InP nanocrystals, which comprises several advantages: (i) the use of simple reagents, namely InCl{sub 3}.4H{sub 2}O and yellow P as the In and P precursors, respectively, and NaBH{sub 4} as the reducing agent in a mixed solvent of ethanol and toluene; (ii) a short reaction time (1-5 h) and low temperature (<75 deg. C); (iii) a high reaction yield approaching 100%. InP NCs in the zinc-blende structure have been obtained as confirmed by powder X-ray diffraction and Raman scattering measurements. Their mean size of 4 nm has been determined by transmission electron microscopy, Raman scattering and absorption spectroscopy.

  1. Low temperature synthesis of InP nanocrystals

    International Nuclear Information System (INIS)

    Ung Thi Dieu Thuy; Tran Thi Thuong Huyen; Nguyen Quang Liem; Reiss, Peter

    2008-01-01

    We present a simple method for the chemical synthesis of InP nanocrystals, which comprises several advantages: (i) the use of simple reagents, namely InCl 3 .4H 2 O and yellow P as the In and P precursors, respectively, and NaBH 4 as the reducing agent in a mixed solvent of ethanol and toluene; (ii) a short reaction time (1-5 h) and low temperature (<75 deg. C); (iii) a high reaction yield approaching 100%. InP NCs in the zinc-blende structure have been obtained as confirmed by powder X-ray diffraction and Raman scattering measurements. Their mean size of 4 nm has been determined by transmission electron microscopy, Raman scattering and absorption spectroscopy

  2. Ruthenium(V) oxides from low-temperature hydrothermal synthesis

    Energy Technology Data Exchange (ETDEWEB)

    Hiley, Craig I.; Walton, Richard I. [Department of Chemistry, University of Warwick, Coventry (United Kingdom); Lees, Martin R. [Department of Physics, University of Warwick, Coventry (United Kingdom); Fisher, Janet M.; Thompsett, David [Johnson Matthey Technology Centre, Reading (United Kingdom); Agrestini, Stefano [Max-Planck Institut, CPfS, Dresden (Germany); Smith, Ronald I. [ISIS Neutron and Muon Source, Rutherford Appleton Laboratory, Harwell Oxford, Didcot (United Kingdom)

    2014-04-22

    Low-temperature (200 C) hydrothermal synthesis of the ruthenium oxides Ca{sub 1.5}Ru{sub 2}O{sub 7}, SrRu{sub 2}O{sub 6}, and Ba{sub 2}Ru{sub 3}O{sub 9}(OH) is reported. Ca{sub 1.5}Ru{sub 2}O{sub 7} is a defective pyrochlore containing Ru{sup V/VI}; SrRu{sub 2}O{sub 6} is a layered Ru{sup V} oxide with a PbSb{sub 2}O{sub 6} structure, whilst Ba{sub 2}Ru{sub 3}O{sub 9}(OH) has a previously unreported structure type with orthorhombic symmetry solved from synchrotron X-ray and neutron powder diffraction. SrRu{sub 2}O{sub 6} exhibits unusually high-temperature magnetic order, with antiferromagnetism persisting to at least 500 K, and refinement using room temperature neutron powder diffraction data provides the magnetic structure. All three ruthenates are metastable and readily collapse to mixtures of other oxides upon heating in air at temperatures around 300-500 C, suggesting they would be difficult, if not impossible, to isolate under conventional high-temperature solid-state synthesis conditions. (copyright 2014 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  3. Room and low temperature synthesis of carbon nanofibres

    International Nuclear Information System (INIS)

    Boskovic, Bojan O.

    2002-01-01

    Carbon nanotubes and nanofibres have attracted attention in recent years as new materials with a number of very promising potential applications. Carbon nanotubes are potential candidates for field emitters in flat panel displays. Carbon nanofibres could also be used as a hydrogen storage material and as a filling material in polymer composites. Carbon nanotubes are already used as tips in scanning probe microscopy due to their remarkable mechanical and electrical properties, and could be soon used as nanotweezers. Use of carbon nanotubes in nanoelectronics will open further miniaturisation prospects. Temperatures ranging from 450 to 1000 deg C have been a required for catalytic growth of carbon nanotubes and nanofibres. Researchers have been trying to reduce the growth temperatures for decades. Low temperature growth conditions will allow the growth of carbon nanotubes on different substrates, such glass (below 650 deg C) and as plastics (below 150 deg C) over relatively large areas, which is especially suitable for fiat panel display applications. Room temperature growth conditions could open up the possibility of using different organic substrates and bio-substrates for carbon nanotubes synthesis. Carbon nanofibres have been synthesised at room temperature and low temperatures below 250 deg C using radio frequency plasma enhanced chemical vapour deposition (r.f. PECVD). Previously, the growth of carbon nanofibres has been via catalytic decomposition of hydrocarbons or carbon monoxide at temperatures above 300 deg C. To the best of our knowledge, this is the first evidence of the growth of carbon nanofibres at temperatures lower than 300 deg C by any method. The use of a transition metal catalyst and r.f.-PECVD system is required for the growth of the carbon nanofibre when a hydrocarbon flows above the catalyst. Within the semiconductor industry r.f.-PECVD is a well established technique which lends itself for the growth of carbon nanofibres for various

  4. Theoretical and experimental researches of methanol clusters in low - temperature matrices

    International Nuclear Information System (INIS)

    Chernolevs'ka, Je.A.; Doroshenko, Yi.Yu.; Pogorelov, V.Je.; Vas'kyivs'kij, Je.V.; Shablyinskas, V.; Balyavyichus, V.; Yasajev, O.

    2015-01-01

    Molecular vibrational spectra of methanol in argon and nitrogen matrices have been studied. Since methanol belongs to a class of substances with hydrogen bonds, there is a possibility of forming molecular associations and clusters with various numbers of molecules. IR spectra of methanol in Ar and N 2 matrices experimentally obtained in the temperature range from 10 to 50 K are compared with the results of computer simulation using the ab initio Car-Parrinello molecular dynamics (CPMD) method. The results obtained for small clusters in model calculations demonstrate a good correlation with experimental data for various matrices at the corresponding temperatures

  5. A Two-Dimensional Multiphysics Coupling Model of a Middle and Low Temperature Solar Receiver/Reactor for Methanol Decomposition

    Directory of Open Access Journals (Sweden)

    Yanjuan Wang

    2017-10-01

    Full Text Available Abstract: In this paper, the endothermic methanol decomposition reaction is used to obtain syngas by transforming middle and low temperature solar energy into chemical energy. A two-dimensional multiphysics coupling model of a middle and low temperature of 150~300 °C solar receiver/reactor was developed, which couples momentum equation in porous catalyst bed, the governing mass conservation with chemical reaction, and energy conservation incorporating conduction/convection/radiation heat transfer. The complex thermochemical conversion process of the middle and low temperature solar receiver/reactor (MLTSRR system was analyzed. The numerical finite element method (FEM model was validated by comparing it with the experimental data and a good agreement was obtained, revealing that the numerical FEM model is reliable. The characteristics of chemical reaction, coupled heat transfer, the components of reaction products, and the temperature fields in the receiver/reactor were also revealed and discussed. The effects of the annulus vacuum space and the glass tube on the performance of the solar receiver/reactor were further studied. It was revealed that when the direct normal irradiation increases from 200 W/m2 to 800 W/m2, the theoretical efficiency of solar energy transformed into chemical energy can reach 0.14–0.75. When the methanol feeding rate is 13 kg/h, the solar flux increases from 500 W/m2 to 1000 W/m2, methanol conversion can fall by 6.8–8.9% with air in the annulus, and methanol conversion can decrease by 21.8–28.9% when the glass is removed from the receiver/reactor.

  6. Evaluation of the Optimum Composition of Low-Temperature Fuel Cell Electrocatalysts for Methanol Oxidation by Combinatorial Screening.

    Science.gov (United States)

    Antolini, Ermete

    2017-02-13

    Combinatorial chemistry and high-throughput screening represent an innovative and rapid tool to prepare and evaluate a large number of new materials, saving time and expense for research and development. Considering that the activity and selectivity of catalysts depend on complex kinetic phenomena, making their development largely empirical in practice, they are prime candidates for combinatorial discovery and optimization. This review presents an overview of recent results of combinatorial screening of low-temperature fuel cell electrocatalysts for methanol oxidation. Optimum catalyst compositions obtained by combinatorial screening were compared with those of bulk catalysts, and the effect of the library geometry on the screening of catalyst composition is highlighted.

  7. Low-temperature graphene synthesis using microwave plasma CVD

    International Nuclear Information System (INIS)

    Yamada, Takatoshi; Kim, Jaeho; Ishihara, Masatou; Hasegawa, Masataka

    2013-01-01

    The graphene chemical vapour deposition (CVD) technique at substrate temperatures around 300 °C by a microwave plasma sustained by surface waves (surface wave plasma chemical vapour deposition, SWP-CVD) is discussed. A low-temperature, large-area and high-deposition-rate CVD process for graphene films was developed. It was found from Raman spectra that the deposited films on copper (Cu) substrates consisted of high-quality graphene flakes. The fabricated graphene transparent conductive electrode showed uniform optical transmittance and sheet resistance, which suggests the possibility of graphene for practical electrical and optoelectronic applications. It is intriguing that graphene was successfully deposited on aluminium (Al) substrates, for which we did not expect the catalytic effect to decompose hydrocarbon and hydrogen molecules. We developed a roll-to-roll SWP-CVD system for continuous graphene film deposition towards industrial mass production. A pair of winder and unwinder systems of Cu film was installed in the plasma CVD apparatus. Uniform Raman spectra were confirmed over the whole width of 297 mm of Cu films. We successfully transferred the deposited graphene onto PET films, and confirmed a transmittance of about 95% and a sheet resistance of less than 7 × 10 5 Ω/sq.

  8. Low-temperature graphene synthesis using microwave plasma CVD

    Science.gov (United States)

    Yamada, Takatoshi; Kim, Jaeho; Ishihara, Masatou; Hasegawa, Masataka

    2013-02-01

    The graphene chemical vapour deposition (CVD) technique at substrate temperatures around 300 °C by a microwave plasma sustained by surface waves (surface wave plasma chemical vapour deposition, SWP-CVD) is discussed. A low-temperature, large-area and high-deposition-rate CVD process for graphene films was developed. It was found from Raman spectra that the deposited films on copper (Cu) substrates consisted of high-quality graphene flakes. The fabricated graphene transparent conductive electrode showed uniform optical transmittance and sheet resistance, which suggests the possibility of graphene for practical electrical and optoelectronic applications. It is intriguing that graphene was successfully deposited on aluminium (Al) substrates, for which we did not expect the catalytic effect to decompose hydrocarbon and hydrogen molecules. We developed a roll-to-roll SWP-CVD system for continuous graphene film deposition towards industrial mass production. A pair of winder and unwinder systems of Cu film was installed in the plasma CVD apparatus. Uniform Raman spectra were confirmed over the whole width of 297 mm of Cu films. We successfully transferred the deposited graphene onto PET films, and confirmed a transmittance of about 95% and a sheet resistance of less than 7 × 105 Ω/sq.

  9. Performance of a combined cooling heating and power system with mid-and-low temperature solar thermal energy and methanol decomposition integration

    International Nuclear Information System (INIS)

    Xu, Da; Liu, Qibin; Lei, Jing; Jin, Hongguang

    2015-01-01

    Highlights: • A new middle-and-low temperature solar thermochemical CCHP system is proposed. • The thermodynamic performances of the new system are numerically evaluated. • The superiorities of the new system are demonstrated. - Abstract: In this paper, a new distributed energy system that integrates the mid-and-low temperature solar energy thermochemical process and the methanol decomposition is proposed. Through the solar energy receiver/reactor, the energy collected by a parabolic trough concentrator, at 200–300 °C, is used to drive the decomposition reaction of the methanol into the synthesis gas, and thus the solar thermal energy is converted to the chemical energy. The chemical energy of the synthesis gas released in the combustion chamber of a micro gas turbine is used to drive the combined cooling heating and power systems. Energy analysis and exergy analysis of the system are implemented to evaluate the feasibility of the proposed system. Under the considerations of the changes of the solar irradiation intensity, the off-design performances of the micro turbine and the variations of the load, the design and off-design thermodynamic performances of the system and the characteristics of the chemical energy storage are numerically studied. Numerical results indicate that the primary energy ratio of the system is 76.40%, and the net solar-electricity conversion rate reaches 22.56%, which is higher than exiting large-scale solar thermal power plants. Owing to the introduction of a the solar thermochemical energy storage in the proposed system, the power generation efficiency is insensitive to the variations of the solar radiation, and thus an efficient and stable utilization approach of the solar thermal energy is achieved at all work condition

  10. Kinetics of the ammonia synthesis at low temperatures. II. Sources of discrepancies

    International Nuclear Information System (INIS)

    Kuchaev, V.L.; Shapatina, E.N.; Temkin, M.I.

    1988-01-01

    A method is developed for calculating the degree of conversion during the synthesis of ammonia in a continuous flow, tubular reactor, taking longitudinal diffusion into account. Such a calculation shows that the available data in the literature on the rate of ammonia synthesis at low temperatures in a tubular reactor agree with the rate equation based on the idea that the predominant intermediate substance is adsorbed ammonia (and not imide). The seeming conflict between this idea and the ratio of the rates of synthesis of ammonia and deuteroammonia at low temperatures is explained

  11. Bimetallic Nickel/Ruthenium Catalysts Synthesized by Atomic Layer Deposition for Low-Temperature Direct Methanol Solid Oxide Fuel Cells.

    Science.gov (United States)

    Jeong, Heonjae; Kim, Jun Woo; Park, Joonsuk; An, Jihwan; Lee, Tonghun; Prinz, Fritz B; Shim, Joon Hyung

    2016-11-09

    Nickel and ruthenium bimetallic catalysts were heterogeneously synthesized via atomic layer deposition (ALD) for use as the anode of direct methanol solid oxide fuel cells (DMSOFCs) operating in a low-temperature range. The presence of highly dispersed ALD Ru islands over a porous Ni mesh was confirmed, and the Ni/ALD Ru anode microstructure was observed. Fuel cell tests were conducted using Ni-only and Ni/ALD Ru anodes with approximately 350 μm thick gadolinium-doped ceria electrolytes and platinum cathodes. The performance of fuel cells was assessed using pure methanol at operating temperatures of 300-400 °C. Micromorphological changes of the anode after cell operation were investigated, and the content of adsorbed carbon on the anode side of the operated samples was measured. The difference in the maximum power density between samples utilizing Ni/ALD Ru and Pt/ALD Ru, the latter being the best catalyst for direct methanol fuel cells, was observed to be less than 7% at 300 °C and 30% at 350 °C. The improved electrochemical activity of the Ni/ALD Ru anode compared to that of the Ni-only anode, along with the reduction of the number of catalytically active sites due to agglomeration of Ni and carbon formation on the Ni surface as compared to Pt, explains this decent performance.

  12. Application of low-temperature plasma for the synthesis of hydrogenated graphene (graphane)

    Science.gov (United States)

    Shavelkina, M. B.; Amirov, R. H.; Katarzhis, V. A.; Kiselev, V. I.

    2017-12-01

    The possibility of a direct synthesis of hydrogenated graphene in decomposition of methane by means of low-temperature plasma was investigated. A DC plasma torch with an expanding channel-anode, a vortex gas supply and a self-setting arc length was used as a generator of low-temperature plasma. Argon was used as the plasma-forming gas. The temperatures of argon plasma and with methane addition to it were determined on the basis of spectral measurements. The synthesis products were characterized by electron microscopy and thermogravimetry. The effect of hydrogenated graphene as a nanomodifier on the properties of the cubic boron nitride based functional ceramics was investigated.

  13. A low-temperature partial-oxidation-methanol micro reformer with high fuel conversion rate and hydrogen production yield

    International Nuclear Information System (INIS)

    Wang, Hsueh-Sheng; Huang, Kuo-Yang; Huang, Yuh-Jeen; Su, Yu-Chuan; Tseng, Fan-Gang

    2015-01-01

    Highlights: • A low-operating temperature of the POM-mode micro methanol reformer is obtained. • The effect of channel design on the performance is studied. • The effect of solid content and binder’ ratio on the performance is studied. • The centrifugal process is benefit for the modification of performance. • 98% of methanol conversion rate of the micro reformer can be obtained at 180 °C. - Abstract: A partial oxidation methanol micro reformer (POM-μReformer) with finger-shaped channels for low operating temperature and high conversing efficiency is proposed in this study. The micro reformer employs POM reaction for low temperature operation (less than 200 °C), exothermic reaction, and quick start-up, as well as air feeding capability; and the finger type reaction chambers for increasing catalyst loading as well as reaction area for performance enhancement. In this study, centrifugal technique was introduced to assist on the catalyst loading with high amount and uniform distribution. The solid content (S), binder’s ratio (B), and channel design (the ratio between channel’s length and width, R) were investigated in detail to optimize the design parameters. Scanning electron microscopy (SEM), gas chromatography (GC), and inductively coupled plasma-mass spectrometer (ICP-MS) were employed to analyze the performance of the POM-μReformer. The result depicted that the catalyst content and reactive area could be much improved at the optimized condition, and the conversion rate and hydrogen selectivity approached 97.9% and 97.4%, respectively, at a very low operating temperature of 180 °C with scarce or no binder in catalyst. The POM-μReformer can supply hydrogen to fuel cells by generating 2.23 J/min for 80% H 2 utilization and 60% fuel cell efficiency at 2 ml/min of supplied reactant gas, including methanol, oxygen and argon at a mixing ratio of 12.2%, 6.1% and 81.7%, respectively

  14. Low-temperature hydrothermal synthesis of ZnO nanorods: Effects of zinc salt concentration, various solvents and alkaline mineralizers

    Energy Technology Data Exchange (ETDEWEB)

    Edalati, Khatereh, E-mail: kh_ed834@stu.um.ac.ir [Department of Metallurgical Engineering, Faculty of Engineering, Ferdowsi University of Mashhad (FUM) Campus, Azadi Sq., Mashhad, Khorasan Razavi (Iran, Islamic Republic of); Shakiba, Atefeh [Department of Material Science and Metallurgy, Amirkabir University of Technology, Tehran (Iran, Islamic Republic of); Vahdati-Khaki, Jalil; Zebarjad, Seyed Mojtaba [Department of Metallurgical Engineering, Faculty of Engineering, Ferdowsi University of Mashhad (FUM) Campus, Azadi Sq., Mashhad, Khorasan Razavi (Iran, Islamic Republic of)

    2016-02-15

    Highlights: • We synthesized ZnO nanorods by a simple hydrothermal process at 60 °C. • Effects of zinc salt concentration, solvent and alkaline mineralizer was studied. • Increasing concentration of zinc salt changed ZnO nucleation system. • NaOH yielded better results in the production of nanorods in both solvents. • Methanol performed better in the formation of nanorods using the two mineralizers. - Abstract: ZnO has been produced using various methods in the solid, gaseous, and liquid states, and the hydrothermal synthesis at low temperatures has been shown to be an environmentally-friendly one. The current work utilizes a low reaction temperature (60 °C) for the simple hydrothermal synthesis of ZnO nanorod morphologies. Furthermore, the effects of zinc salt concentration, solvent type and alkaline mineralizer type on ZnO nanorods synthesis at a low reaction temperature by hydrothermal processing was studied. Obtained samples were analyzed using X-ray powder diffraction (XRD) and scanning electron microscopy (SEM). Increasing the concentration of the starting zinc salt from 0.02 to 0.2 M changed ZnO nucleation system from the homogeneous to the heterogeneous state. The XRD results confirmed the production hexagonal ZnO nanostructures of with a crystallite size of 40.4 nm. Varying the experimental parameters (mineralizer and solvent) yielded ZnO nanorods with diameters ranging from 90–250 nm and lengths of 1–2 μm.

  15. Low Temperature Synthesis and Properties of Gadolinium-Doped Cerium Oxide Nanoparticles

    DEFF Research Database (Denmark)

    Machado, Marina F. S.; P. R. Moraes, Leticia; Monteiro, Natalia K.

    2017-01-01

    Gadolinium-doped cerium oxide (GDC) is an attractive ceramic material for solid oxide fuel cells (SOFCs) both as the electrolyte or in composite electrodes. The Ni/GDC cermet can be tuned as a catalytic layer, added to the conventional Ni/yttria-stabilized zirconia (YSZ), for the internal steam...... sintering temperature needed to obtain a fully dense ceramic body, which can result in undesired reactions with YSZ. In this study, a green chemistry route for the synthesis of 10 mol% GDC nanoparticles is proposed. Such a low temperature synthesis provides control over particle size and sinterability...

  16. Low temperature synthesis of graphene on arbitrary substrates and its transport properties

    Science.gov (United States)

    Zhao, Rong; Akhtar, Meysam; Alruqi, Adel; Jasinski, Jacek; Sumanasekera, Gamini; Department of Physics; Astronomy, University of Louisville Collaboration; Conn CenterRenewable Energy, University of Louisville Collaboration

    Here we report the direct synthesis of uniform and vertically oriented graphene films on multiple substrates including glass, Si/SiO2, and copper foil by radio-frequency plasma enhanced chemical vapor deposition (PECVD) using methane as the carbon precursor at relatively low temperatures. Raman spectra of all the samples show characteristic Raman peaks of graphene. The temperature dependence of electrical transport properties such as 4-probe resistance, thermo electrical power and hall mobility were measured for graphene grown on glass substrates at varying temperature from 500 ° C to 700 ° C. The morphological and surface characteristics were also studied by scanning electron microscopy (SEM) and transmission electron microscopy (TEM). This work demonstrates the potential of low temperature and transfer-free graphene growth for future graphene-based electronic applications.

  17. Low-temperature direct synthesis of mesoporous vanadium nitrides for electrochemical capacitors

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Hae-Min [Institute of NT-IT Fusion Technology, Ajou University, 206 Worldcup-ro, Yeongtong-gu, Suwon 16499 (Korea, Republic of); Jeong, Gyoung Hwa [Department of Chemistry, Ulsan National Institute of Science and Technology (UNIST), Banyeon 100, Ulsan 44919 (Korea, Republic of); Kim, Sang-Wook [Department of Molecular Science and Technology, Ajou University, 206 Worldcup-ro, Yeongtong-gu, Suwon 16499 (Korea, Republic of); Kim, Chang-Koo, E-mail: changkoo@ajou.ac.kr [Department of Chemical Engineering and Department of Energy Systems Research, Ajou University, 206 Worldcup-ro, Yeongtong-gu, Suwon 16499 (Korea, Republic of)

    2017-04-01

    Highlights: • Vanadium nitrides were directly synthesized by a one-step chemical precipitation method. • This method was carried out at a low temperature of 70 °C. • Vanadium nitrides had a specific capacitance of 598 F/g. • The equivalent series resistance of the vanadium nitride electrode was 1.42 Ω after 5000 cycles. - Abstract: Mesoporous vanadium nitrides are directly synthesized by a one-step chemical precipitation method at a low temperature (70 °C). Structural and morphological analyses reveal that vanadium nitride consist of long and slender nanowhiskers, and mesopores with diameters of 2–5 nm. Compositional analysis confirms the presence of vanadium in the VN structure, along with oxidized vanadium. The cyclic voltammetry and charge-discharge tests indicate that the obtained material stores charges via a combination of electric double-layer capacitance and pseudocapacitance mechanisms. The vanadium nitride electrode exhibits a specific capacitance of 598 F/g at a current density of 4 A/g. After 5000 charge-discharge cycles, the electrode has an equivalent series resistance of 1.42 Ω and retains 83% of its initial specific capacitance. This direct low-temperature synthesis of mesoporous vanadium nitrides is a simple and promising method to achieve high specific capacitance and low equivalent series resistance for electrochemical capacitor applications.

  18. Synthesis of MIL-100(Fe at Low Temperature and Atmospheric Pressure

    Directory of Open Access Journals (Sweden)

    Jing Shi

    2013-01-01

    Full Text Available MIL-100(Fe, a mesoporous metal-organic framework (MOF, has a large BET specific surface area and pore volume with the presence of a significant amount of accessible Lewis acid metal sites upon dehydration. The structural characteristics of MIL-100(Fe make it a good candidate for potential applications in gas storage, separation, and heterogeneous catalysis. Mainly, this MOF is obtained by the hydrothermal synthesis in a Teflon-lined autoclave at high temperature (>150°C under static conditions. However, this method has several disadvantages such as high temperature, high (autogenous pressure, long time, and comparable low MOF yield. Therefore, development of a facile method for synthesis of MIL-100(Fe is vitally important for fundamental understanding and practical application. Herein, MIL-100(Fe is synthesized by a facile low-temperature (90% still could be achieved, suggesting that this simple and energy saving method has the potential to be used practically.

  19. Low-temperature synthesis of graphene on nickel foil by microwave plasma chemical vapor deposition

    International Nuclear Information System (INIS)

    Kim, Y.; Song, W.; Lee, S. Y.; Jeon, C.; Jung, W.; Kim, M.; Park, C.-Y.

    2011-01-01

    Microwave plasma chemical vapor deposition (MPCVD) was employed to synthesize high quality centimeter scale graphene film at low temperatures. Monolayer graphene was obtained by varying the gas mixing ratio of hydrogen and methane to 80:1. Using advantages of MPCVD, the synthesis temperature was decreased from 750 deg. C down to 450 deg. C. Optical microscopy and Raman mapping images exhibited that a large area monolayer graphene was synthesized regardless of the temperatures. Since the overall transparency of 89% and low sheet resistances ranging from 590 to 1855 Ω/sq of graphene films were achieved at considerably low synthesis temperatures, MPCVD can be adopted in manufacturing future large-area electronic devices based on graphene film.

  20. Low-temperature synthesis of graphene on nickel foil by microwave plasma chemical vapor deposition

    Science.gov (United States)

    Kim, Y.; Song, W.; Lee, S. Y.; Jeon, C.; Jung, W.; Kim, M.; Park, C.-Y.

    2011-06-01

    Microwave plasma chemical vapor deposition (MPCVD) was employed to synthesize high quality centimeter scale graphene film at low temperatures. Monolayer graphene was obtained by varying the gas mixing ratio of hydrogen and methane to 80:1. Using advantages of MPCVD, the synthesis temperature was decreased from 750 °C down to 450 °C. Optical microscopy and Raman mapping images exhibited that a large area monolayer graphene was synthesized regardless of the temperatures. Since the overall transparency of 89% and low sheet resistances ranging from 590 to 1855 Ω/sq of graphene films were achieved at considerably low synthesis temperatures, MPCVD can be adopted in manufacturing future large-area electronic devices based on graphene film.

  1. Synthesis of ZnO Nanostructures for Low Temperature CO and UV Sensing

    Directory of Open Access Journals (Sweden)

    Nazar Abbas Shah

    2012-10-01

    Full Text Available In this paper, synthesis and results of the low temperature sensing of carbon monoxide (CO gas and room temperature UV sensors using one dimensional (1-D ZnO nanostructures are presented. Comb-like structures, belts and rods, and needle-shaped nanobelts were synthesized by varying synthesis temperature using a vapor transport method. Needle-like ZnO nanobelts are unique as, according to our knowledge, there is no evidence of such morphology in previous literature. The structural, morphological and optical characterization was carried out using X-ray diffraction, scanning electron microscopy and diffused reflectance spectroscopy techniques. It was observed that the sensing response of comb-like structures for UV light was greater as compared to the other grown structures. Comb-like structure based gas sensors successfully detect CO at 75 °C while other structures did not show any response.

  2. Improving Performance and Operational Stability of Porcine Interferon-α Production by Pichia pastoris with Combinational Induction Strategy of Low Temperature and Methanol/Sorbitol Co-feeding.

    Science.gov (United States)

    Gao, Min-Jie; Zhan, Xiao-Bei; Gao, Peng; Zhang, Xu; Dong, Shi-Juan; Li, Zhen; Shi, Zhong-Ping; Lin, Chi-Chung

    2015-05-01

    Various induction strategies were investigated for effective porcine interferon-α (pIFN-α) production by Pichia pastoris in a 10 L fermenter. We found that pIFN-α concentration could be significantly improved with the strategies of low-temperature induction or methanol/sorbitol co-feeding. On this basis, a combinational strategy of induction at lower temperature (20 °C) with methanol/sorbitol co-feeding has been proposed for improvement of pIFN-α production. The results reveal that maximal pIFN-α concentration and antiviral activity reach the highest level of 2.7 g/L and 1.8 × 10(7) IU/mg with the proposed induction strategy, about 1.3-2.1 folds higher than those obtained with other sub-optimal induction strategies. Metabolic analysis and online multi-variable measurement results indicate that energy metabolic enrichment is responsible for the performance enhancement of pIFN-α production, as a large amount of ATP could be simultaneously produced from both formaldehyde oxidation pathway in methanol metabolism and tricarboxylic acid (TCA) cycle in sorbitol metabolism. In addition, the proposed combinational induction strategy enables P. pastoris to be resistant to high methanol concentration (42 g/L), which conceivably occur associating with the error-prone methanol over-feeding. As a result, the proposed combinational induction strategy simultaneously increased the targeted protein concentration and operational stability leading to significant improvement of pIFN-α production.

  3. The facile and low temperature synthesis of nanophase hydroxyapatite crystals using wet chemistry

    International Nuclear Information System (INIS)

    Dhand, Vivek; Rhee, K.Y.; Park, Soo-Jin

    2014-01-01

    A simple and facile wet chemistry route was used to synthesize nanophase hydroxyapatite (HaP) crystals at low temperature. The synthesis was carried out at a pH of 11.0 and at a temperature of 37 °C. The resulting samples were washed several times and subjected to further analysis. XRD studies revealed that the HaP crystals were polycrystalline in nature with a crystallite size of ∼ 15–60 ± 5 nm. SEM-EDXA images confirmed the presence of calcium (Ca), phosphorous (P), and oxygen (O) peaks. Likewise, FTIR confirmed the presence of characteristic phosphate and hydroxyl peaks in samples. Lastly, HRTEM images clearly showed distinctive lattice fringes positioned in the 100 and 002 planes. TGA analysis shows that HaP crystals can withstand higher calcination temperatures and are thermally stable. - Highlights: • Facile and low temperature nanophase HaP crystals synthesized at pH 11 and 37 °C • Electron microscopy image of HaP shows characteristic rice grain like morphology. • FTIR results show the characteristic and fingerprint functional groups of HaP. • Thermal stability of HaP crystals up to 500 °C • Growth of Hap crystals occur parallel to c-axis and a possible mechanism proposed

  4. Low temperature synthesis and field emission characteristics of single to few layered graphene grown using PECVD

    Energy Technology Data Exchange (ETDEWEB)

    Kumar, Avshish; Khan, Sunny; Zulfequar, M.; Harsh; Husain, Mushahid, E-mail: mush_reslab@rediffmail.com

    2017-04-30

    Highlights: • Graphene was synthesized by PECVD system at a low temperature of 600 °C. • From different characterization techniques, the presence of single and few layered graphene was confirmed. • X-ray diffraction pattern of the graphene showed single crystalline nature of the film. • The as-grown graphene films were observed extremely good field emitters with long term emission current stability. - Abstract: In this work, high-quality graphene has successfully been synthesized on copper (Cu) coated Silicon (Si) substrate at very large-area by plasma enhanced chemical vapor deposition system. This method is low cost and highly effective for synthesizing graphene relatively at low temperature of 600 °C. Electron microscopy images have shown that surface morphology of the grown samples is quite uniform consisting of single layered graphene (SLG) to few layered graphene (FLG). Raman spectra reveal that graphene has been grown with high-quality having negligible defects and the observation of G and G' peaks is also an indicative of stokes phonon energy shift caused due to laser excitation. Scanning probe microscopy image also depicts the synthesis of single to few layered graphene. The field emission characteristics of as-grown graphene samples were studied in a planar diode configuration at room temperature. The graphene samples were observed to be a good field emitter having low turn-on field, higher field amplification factor and long term emission current stability.

  5. Low-temperature direct synthesis of mesoporous vanadium nitrides for electrochemical capacitors

    Science.gov (United States)

    Lee, Hae-Min; Jeong, Gyoung Hwa; Kim, Sang-Wook; Kim, Chang-Koo

    2017-04-01

    Mesoporous vanadium nitrides are directly synthesized by a one-step chemical precipitation method at a low temperature (70 °C). Structural and morphological analyses reveal that vanadium nitride consist of long and slender nanowhiskers, and mesopores with diameters of 2-5 nm. Compositional analysis confirms the presence of vanadium in the VN structure, along with oxidized vanadium. The cyclic voltammetry and charge-discharge tests indicate that the obtained material stores charges via a combination of electric double-layer capacitance and pseudocapacitance mechanisms. The vanadium nitride electrode exhibits a specific capacitance of 598 F/g at a current density of 4 A/g. After 5000 charge-discharge cycles, the electrode has an equivalent series resistance of 1.42 Ω and retains 83% of its initial specific capacitance. This direct low-temperature synthesis of mesoporous vanadium nitrides is a simple and promising method to achieve high specific capacitance and low equivalent series resistance for electrochemical capacitor applications.

  6. Foundations of low-temperature plasma enhanced materials synthesis and etching

    Science.gov (United States)

    Oehrlein, Gottlieb S.; Hamaguchi, Satoshi

    2018-02-01

    Low temperature plasma (LTP)-based synthesis of advanced materials has played a transformational role in multiple industries, including the semiconductor industry, liquid crystal displays, coatings and renewable energy. Similarly, the plasma-based transfer of lithographically defined resist patterns into other materials, e.g. silicon, SiO2, Si3N4 and other electronic materials, has led to the production of nanometer scale devices that are the basis of the information technology, microsystems, and many other technologies based on patterned films or substrates. In this article we review the scientific foundations of both LTP-based materials synthesis at low substrate temperature and LTP-based isotropic and directional etching used to transfer lithographically produced resist patterns into underlying materials. We cover the fundamental principles that are the basis of successful application of the LTP techniques to technological uses and provide an understanding of technological factors that may control or limit material synthesis or surface processing with the use of LTP. We precede these sections with a general discussion of plasma surface interactions, the LTP-generated particle fluxes including electrons, ions, radicals, excited neutrals and photons that simultaneously contact and modify surfaces. The surfaces can be in the line of sight of the discharge or hidden from direct interaction for structured substrates. All parts of the article are extensively referenced, which is intended to help the reader study the topics discussed here in more detail.

  7. Effect of reducing agents on low-temperature synthesis of nanostructured LiFePO4

    Science.gov (United States)

    Kulka, Andrzej; Walczak, Katarzyna; Zając, Wojciech; Molenda, Janina

    2017-09-01

    Simple co-precipitation synthesis procedure yielding nanometric LiFePO4 with enhanced electrochemical properties without any post-synthesis heat treatment is presented. XRD, SEM and TEM analysis of the obtained powders revealed platelet crystallites and well crystalized bulk structure. Effective way of decreasing amount of Fe3+ containing phases by addition of reducing agents (KI, (NH4)2S2O3, glucose and the atmosphere of 5%H2-95%Ar) during low-temperature (107 °C) synthesis is described. The traditional analytical chemistry methods or the Mӧssbauer spectroscopy methods revealed that utilization of selected reducing agents diminished Fe3+ concentration from 25 to 12 at%. The constructed cells with optimized LiFePO4 as a cathode material showed superior electrochemical performances, including high reversible capacity up to 162 mAh/g at C/10 current discharge rate, flat voltage plateau with a value close to 3.45 V vs. Li0/+.

  8. Low-temperature synthesis and structural properties of ferroelectric K 3WO 3F 3 elpasolite

    Science.gov (United States)

    Atuchin, V. V.; Gavrilova, T. A.; Kesler, V. G.; Molokeev, M. S.; Aleksandrov, K. S.

    2010-06-01

    Low-temperature ferroelectric G2 polymorph of K 3WO 3F 3 has been prepared by chemical synthesis. Structural and chemical properties of the final product have been evaluated with X-ray powder diffraction (XRD), scanning electron microscopy (SEM) and X-ray photoelectron spectroscopy (XPS). Structure parameters of G2-K 3WO 3F 3 are refined by the Rietveld method from XRD data measured at room temperature (space group Cm, Z = 2, a = 8.7350(3) Å, b = 8.6808(5) Å, c = 6.1581(3) Å, β = 135.124(3) Å, V = 329.46(3) Å 3; RB = 2.47%). Partial ordering of oxygen and fluorine atoms has been found over anion positions. Mechanism of ferroelectric phase transition in A 2BMO 3F 3 oxyfluorides is discussed.

  9. Advantage of low-temperature hydrothermal synthesis to grow stoichiometric crednerite crystals

    Science.gov (United States)

    Poienar, Maria; Martin, Christine; Lebedev, Oleg I.; Maignan, Antoine

    2018-06-01

    This work reports a new approach for the growth of stoichiometric crednerite CuMnO2 crystals. The hydrothermal reaction, starting from soluble metal sulphates as precursors, is assisted by ethylene glycol and the formation of crednerite is found to depend strongly on pH and temperature. This method allows obtaining small hexagonal platelets with the larger dimension about 1.0-1.5 μm and with a composition characterized by a Cu/Mn ratio of 1. Thus, these crystals differ from the needle-like millimetric ones obtained by the flux technique for which the composition departs from the expected one and is close to Cu1.04Mn0.96. This monitoring of the cationic composition in crednerite, using hydrothermal synthesis, is important as the Cu/Mn ratio controls the low temperature antiferromagnetic ground-state.

  10. Low-temperature synthesis of allyl dimethylamine by selective heating under microwave irradiation used for water treatment

    International Nuclear Information System (INIS)

    Tian Binghui; Luan Zhaokun; Li Mingming

    2005-01-01

    Low-temperature synthesis of allyl dimethylamine (ADA) by selective heating under microwave irradiation (MI) used for water treatment is investigated. The effect of MI, ultrasound irradiation (UI) and conventional heating on yield of ADA, reaction time and the flocculation efficiency of polydiallyl dimethylammunion chloride (PDADMAC) prepared form ADA were studied. The results show that by selective heating at low temperature, MI not only increases yield of ADA and reduces reaction time, but also greatly enhances the flocculation efficiency of PDADMAC

  11. Low temperature synthesis of hydroxyapatite nano-rods by a modified sol-gel technique

    International Nuclear Information System (INIS)

    Jadalannagari, Sushma; More, Sandeep; Kowshik, Meenal; Ramanan, Sutapa Roy

    2011-01-01

    Hydroxyapatite (HAp) nano-rods were successfully synthesized by a modified sol-gel method using a solution of CaCl 2 .2H 2 O in water, along with a solution of H 3 PO 4 in triethylamine and NH 4 OH as starting materials. The Ca/P molar ratio was maintained at 1.67. The sol obtained was dried in an oven for 2 days at 100 deg. C after being dialyzed for 12 h. Pellets were made from the crystalline powders and immersed in simulated body fluid (SBF) to check its biocompatibility after 15, 45 and 180 days of immersion. The HAp powders and pellets were characterized by X-Ray Diffraction crystallography (XRD), Fourier transform Infrared spectroscopy (FTIR), scanning electron microscopy (SEM), and Transmission electron microscopy (TEM). The HAp nano-rods had an average diameter of 25 nm and length 110-120 nm. Immersion of the HAp pellets in SBF led to the formation of a highly porous interconnecting HAp layer on the surface. The porosity increased with increase in immersion time. Highlights: → Low temperature synthesis of hydroxyapatite nanorods using Ca and P sources and triethylamine. → The synthesis time was only 0.5 hours. → Crystalline material was obtained after drying at 100oC only in air. → SBF studies showed the HAP bodies to be biocompatible.

  12. Synthesis of Li2SiO3 at low temperature

    International Nuclear Information System (INIS)

    Mondragon G, G.

    2007-01-01

    The main objective of this work is to develop a new synthesis method to obtain one of the more studied ceramics in this field Li 2 SiO 3 ) in a simple and economic way using different solutions (urea and ammonium hydroxide). The particular objectives are first to prepare the Li 2 SiO 3 ceramic, by means of the use of the reaction conventional technique in solid state at temperatures between 800 and 900 C to compare it with the one proposed in this work and this way to observe the advantages that it would gives us the new method. Later on, the same one was synthesized lithium ceramic (Li 2 SiO 3 ) by means of the new method at low temperature (between 80 and 90 C), using silicic acid and lithium hydroxide like precursory reagents and different solutions (urea and ammonium hydroxide) for the optimization in their synthesis. Finally, it was carried out the characterization of these materials by means of X-ray diffraction (XRD), electronic microscopes (SEM and TEM), nitrogen physisorption (method BET) and thermal gravimetric analysis (TGA) to observe the differences that exist among the conventional method and the proposed method and by this way to determine the advantages of the last method. (Author)

  13. Novel efficient process for methanol synthesis by CO2 hydrogenation

    NARCIS (Netherlands)

    Kiss, Anton Alexandru; Pragt, J.J.; Vos, H.J.; Bargeman, Gerrald; de Groot, M.T.

    2016-01-01

    Methanol is an alternative fuel that offers a convenient solution for efficient energy storage. Complementary to carbon capture activities, significant effort is devoted to the development of technologies for methanol synthesis by hydrogenation of carbon dioxide. While CO2 is available from plenty

  14. Kinetically controlled synthesis of large-scale morphology-tailored silver nanostructures at low temperature

    Science.gov (United States)

    Zhang, Ling; Zhao, Yuda; Lin, Ziyuan; Gu, Fangyuan; Lau, Shu Ping; Li, Li; Chai, Yang

    2015-08-01

    Ag nanostructures are widely used in catalysis, energy conversion and chemical sensing. Morphology-tailored synthesis of Ag nanostructures is critical to tune physical and chemical properties. In this study, we develop a method for synthesizing the morphology-tailored Ag nanostructures in aqueous solution at a low temperature (45 °C). With the use of AgCl nanoparticles as the precursor, the growth kinetics of Ag nanostructures can be tuned with the pH value of solution and the concentration of Pd cubes which catalyze the reaction. Ascorbic acid and cetylpyridinium chloride are used as the mild reducing agent and capping agent in aqueous solution, respectively. High-yield Ag nanocubes, nanowires, right triangular bipyramids/cubes with twinned boundaries, and decahedra are successfully produced. Our method opens up a new environmentally-friendly and economical route to synthesize large-scale and morphology-tailored Ag nanostructures, which is significant to the controllable fabrication of Ag nanostructures and fundamental understanding of the growth kinetics.Ag nanostructures are widely used in catalysis, energy conversion and chemical sensing. Morphology-tailored synthesis of Ag nanostructures is critical to tune physical and chemical properties. In this study, we develop a method for synthesizing the morphology-tailored Ag nanostructures in aqueous solution at a low temperature (45 °C). With the use of AgCl nanoparticles as the precursor, the growth kinetics of Ag nanostructures can be tuned with the pH value of solution and the concentration of Pd cubes which catalyze the reaction. Ascorbic acid and cetylpyridinium chloride are used as the mild reducing agent and capping agent in aqueous solution, respectively. High-yield Ag nanocubes, nanowires, right triangular bipyramids/cubes with twinned boundaries, and decahedra are successfully produced. Our method opens up a new environmentally-friendly and economical route to synthesize large-scale and morphology

  15. Novel low temperature synthesis of spinel nano-magnesium chromites from secondary resources

    Energy Technology Data Exchange (ETDEWEB)

    El-Sheikh, S.M., E-mail: selsheikh2001@gmail.com [Nanostructured Materials Laboratory, Advanced Material Department, Central Metallurgical R and D Institute (CMRDI), P.O. Box 78, Helwan, 11421 Cairo (Egypt); Rabbah, M., E-mail: mahmoud.rabah@ymail.com [Electrochemical and Chemical Treatment Laboratory, Minerals Department, Central Metallurgical R and D Institute (CMRDI), P.O. Box 78, Helwan, 11421 Cairo (Egypt)

    2013-09-20

    Graphical abstract: FE-SEM micrograph and TEM image of magnesium chromite sample heated at 500 °C. - Highlights: • No study has been reported to prepare spinel magnesium chromite form waste resources. • Novel low synthesis temperature of magnesium chromite. • Selective removal of Ca ions from industrial waste tannery solution is rarely reported. • The method applied is simple and safe. - Abstract: A novel low temperature method for synthesis of nano-crystalline magnesium chromites from the tannery waste solution was investigated. Magnesium and chromium hydroxides gel was co-precipitated at pH 8.5 using ammonia solution. MgCr{sub 2}O{sub 4} was obtained by heating the gel formed at different temperatures 300–500 °C for to 8 h. FT-IR, TG-DTG-DTA, FE-SEM and TEM were used to investigate the produced materials. XRD patterns of the primary oxides revealed the formation of amorphous oxide phase by heating at 300 °C. Heating at 400 °C produces nano-crystallite magnesium chromites partly having the structure MgCrO{sub 4} and mainly MgCr{sub 2}O{sub 4} and traces of Cr{sub 2}O{sub 3}{sup +} 500 °C MgCrO{sub 4} mostly decomposed into MgCr{sub 2}O{sub 4} structure{sub .} After 8 h of heating at 500 °C, Cr{sub 2}O{sub 3} completely disappeared. A high surface area about 42.6 m{sup 2}/g and mesoporous structure was obtained for the produced sample at 500 °C for 8 h. A thermodynamic model has been suggested to explain the findings.

  16. Urea-assisted low temperature green synthesis of graphene nanosheets for transparent conducting film

    Science.gov (United States)

    Chamoli, Pankaj; Das, Malay K.; Kar, Kamal K.

    2018-02-01

    Present work demonstrates the fabrication of graphene nanosheet (GN) based transparent conducting film (TCF) using spray coating. Green synthesis of GN is carried out by reduction of graphene oxide (GO) using urea as green reducing agent. The reductive ability of urea with varied concentration is studied for GO at low temperature (i.e., 90 °C). As synthesized graphene nanosheets (GNs) are characterized by Raman spectroscopy, Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), UV-visible spectroscopy, field emission scanning electron microscopy (FESEM), atomic force microscope (AFM), and X-ray Photon spectroscopy (XPS). Raman analysis confirms that the maximum reduction of oxygen species is noticed using 30 mg/ml urea concentration at 90 °C from GO, and found Raman D to G band ratio (ID/IG) of ∼1.30. XPS analysis validates the Raman signature of removal of oxygen functional groups from GO, and obtained C/O ratio of ∼5.28. Further, transparent conducting films (TCFs) are fabricated using synthesized GNs. Thermal graphitization is carried out to enhance the optical and electrical properties of TCFs. TCF shows best performance when it is annealed at 900 °C for 1 h in vacuum, and obtained sheet resistance is ∼1.89 kΩ/□ with transmittance of ∼62.53%.

  17. Heat-equilibrium low-temperature plasma decay in synthesis of ammonia via transient components N2H6

    International Nuclear Information System (INIS)

    Cao Guobin; Song Youqun; Chen Qing; Zhou Qiulan; Cao Yun; Wang Chunhe

    2001-01-01

    The author introduced a new method of heat-equilibrium low-temperature plasma in ammonia synthesis and a technique of continuous real-time inlet sampling mass-spectrometry to detect the reaction channel and step of the decay of transient component N 2 H 6 into ammonia. The experimental results indicated that in the process of ammonia synthesis by discharge of N 2 and H 2 mixture, the transient component N 2 H 6 is a necessary step

  18. Low temperature synthesis of Ba1–xSrxSnO3 (x= 0–1) from molten ...

    Indian Academy of Sciences (India)

    ... Lecture Workshops · Refresher Courses · Symposia · Live Streaming. Home; Journals; Bulletin of Materials Science; Volume 33; Issue 1. Low temperature synthesis of Ba1–SrSnO3 ( = 0–1) from molten alkali hydroxide flux. B Ramdas R Vijayaraghavan. Electrical Properties Volume 33 Issue 1 February 2010 pp 75- ...

  19. Low temperature solution synthesis of zinc antimonide, manganese antimonide, and strontium ruthenate compounds

    Science.gov (United States)

    Noblitt, Jennifer Lenkner

    2011-12-01

    Mn2Sb may be electrochemically deposited on a conducting substrate. Increasing use of natural resources for energy generation has driven research in the area of energy storage using superconducting materials. To meet energy storage needs the materials must have the following features: (i) safety, (ii) superconductivity at or above liquid nitrogen temperature (77 K), (iii) low cost manufacturing processes, and (iv) robustness. The search for materials that meet all of these criteria is on-going, specifically in the area of high temperature superconductivity. The precise mechanism of superconductivity is not known. A few theories explain some of the phenomenological aspects, but not all. In order to logically select and synthesize high temperature superconductors for industrial applications, the precise mechanism must first be elucidated. Additionally, a synthetic method that yields pure, high quality crystals is required because transition temperatures have been shown to vary depending on the preparation method due to impurities. Before measuring properties of superconductors, the development of a synthesis method that yields pure, high quality crystals is required. Most superconductors are synthesized using traditional solid state methods. This synthesis route precludes formation of kinetically stable phases. Low temperature synthesis is useful for probing thermodynamic verses kinetic stability of compounds as well as producing high quality single crystals. A novel low temperature hydrothermal synthesis of Sr-Ru-O compounds has been developed. These materials are important because of their interesting properties including superconductivity and ferromagnetism. Sr2RuO4 is particularly interesting as it is superconducting and isostructural to La2CuO 4, which is only superconducting when doped. Therefore, Sr2RuO 4 is a good choice for study of the mechanism of superconductivity. Additionally, new kinetically stable phases of the Sr-Ru-O family may be formed which may

  20. Synthesis of high saturation magnetic iron oxide nanomaterials via low temperature hydrothermal method

    Energy Technology Data Exchange (ETDEWEB)

    Bhavani, P.; Rajababu, C.H. [Department of Materials Science & Nanotechnology, Yogivemana University, Vemanapuram 516003, Kadapa (India); Arif, M.D. [Environmental Magnetism Laboratory, Indian Institute of Geomagnetism (IIG), Navi Mumbai 410218, Mumbai (India); Reddy, I. Venkata Subba [Department of Physics, Gitam University, Hyderabad Campus, Rudraram, Medak 502329 (India); Reddy, N. Ramamanohar, E-mail: manoharphd@gmail.com [Department of Materials Science & Nanotechnology, Yogivemana University, Vemanapuram 516003, Kadapa (India)

    2017-03-15

    Iron oxide nanoparticles (IONPs) were synthesized through a simple low temperature hydrothermal approach to obtain with high saturation magnetization properties. Two series of iron precursors (sulfates and chlorides) were used in synthesis process by varying the reaction temperature at a constant pH. The X-ray diffraction pattern indicates the inverse spinel structure of the synthesized IONPs. The Field emission scanning electron microscopy and high resolution transmission electron microscopy studies revealed that the particles prepared using iron sulfate were consisting a mixer of spherical (16–40 nm) and rod (diameter ~20–25 nm, length <100 nm) morphologies that synthesized at 130 °C, while the IONPs synthesized by iron chlorides are found to be well distributed spherical shapes with size range 5–20 nm. On other hand, the IONPs synthesized at reaction temperature of 190 °C has spherical (16–46 nm) morphology in both series. The band gap values of IONPs were calculated from the obtained optical absorption spectra of the samples. The IONPs synthesized using iron sulfate at temperature of 130 °C exhibited high saturation magnetization (M{sub S}) of 103.017 emu/g and low remanant magnetization (M{sub r}) of 0.22 emu/g with coercivity (H{sub c}) of 70.9 Oe{sub ,} which may be attributed to the smaller magnetic domains (d{sub m}) and dead magnetic layer thickness (t). - Highlights: • Comparison of iron oxide materials prepared with Fe{sup +2}/Fe{sup +3} sulfates and chlorides at different temperatures. • We prepared super-paramagnetic and soft ferromagnetic magnetite nanoparticles. • We report higher saturation magnetization with lower coercivity.

  1. Low temperature synthesis of ternary metal phosphides using plasma for asymmetric supercapacitors

    KAUST Repository

    Liang, Hanfeng; Xia, Chuan; Jiang, Qiu; Gandi, Appala; Schwingenschlö gl, Udo; Alshareef, Husam N.

    2017-01-01

    We report a versatile route for the preparation of metal phosphides using PH plasma for supercapacitor applications. The high reactivity of plasma allows rapid and low temperature conversion of hydroxides into monometallic, bimetallic, or even more

  2. A Review of Study on Thermal Energy Transport System by Synthesis and Decomposition Reactions of Methanol

    Science.gov (United States)

    Liu, Qiusheng; Yabe, Akira; Kajiyama, Shiro; Fukuda, Katsuya

    The study on thermal energy transport system by synthesis and decomposition reactions of methanol was reviewed. To promote energy conservation and global environment protection, a two-step liquid-phase methanol synthesis process, which starts with carbonylation of methanol to methyl formate, then followed by the hydrogenolysis of the formate, was studied to recover wasted or unused discharged heat from industrial sources for the thermal energy demands of residential and commercial areas by chemical reactions. The research and development of the system were focused on the following three points. (1) Development of low-temperature decomposition and synthetic catalysts, (2) Development of liquid phase reactor (heat exchanger accompanying chemical reaction), (3) Simulation of the energy transport efficiency of entire system which contains heat recovery and supply sections. As the result of the development of catalyst, promising catalysts which agree with the development purposes for the methyl formate decomposition reaction and the synthetic reaction are being developed though some studies remain for the methanol decomposition and synthetic reactions. In the fundamental development of liquid phase reactor, the solubilities of CO and H2 gases in methanol and methyl formate were measured by the method of total pressure decrease due to absorption under pressures up to 1500kPa and temperatures up to 140°C. The diffusivity of CO gas in methanol was determined by measuring the diameter and solution time of single CO bubbles in methanol. The chemical reaction rate of methanol synthesis by hydrogenolysis of methyl formate was measured using a plate-type of Raney copper catalyst in a reactor with rectangular channel and in an autoclave reactor. The reaction characteristics were investigated by carrying out the experiments at various temperatures, flow rates and at various catalyst development conditions. We focused on the effect of Raney copper catalyst thickness on the liquid

  3. Growth Mechanism for Low Temperature PVD Graphene Synthesis on Copper Using Amorphous Carbon

    Science.gov (United States)

    Narula, Udit; Tan, Cher Ming; Lai, Chao Sung

    2017-03-01

    Growth mechanism for synthesizing PVD based Graphene using Amorphous Carbon, catalyzed by Copper is investigated in this work. Different experiments with respect to Amorphous Carbon film thickness, annealing time and temperature are performed for the investigation. Copper film stress and its effect on hydrogen diffusion through the film grain boundaries are found to be the key factors for the growth mechanism, and supported by our Finite Element Modeling. Low temperature growth of Graphene is achieved and the proposed growth mechanism is found to remain valid at low temperatures.

  4. Short Review: Mitigation of Current Environmental Concerns from Methanol Synthesis

    Directory of Open Access Journals (Sweden)

    Andrew Young

    2013-06-01

    Full Text Available Methanol has become a widely used and globally distributed product. Methanol is very important due to the current depletion of fossil fuels. Industrially, methanol produced from the catalytic reaction of synthetic gas composed of hydrogen, carbon monoxide, and carbon dioxide. Methanol production has brought great attention due to carbon dioxide as the main source of greenhouse gas emissions. Combined of reducing CO2 emissions and supplying an alternative fuel source has created the idea of a carbon neutral cycle called “the methanol economy”. The best catalyst for the methanol economy would show a high CO2 conversion and high selectivity for methanol production. This paper investigates research focused on catalyst development for efficient methanol synthesis from hydrogenation of carbon dioxide through added various supports and additives such as silica, zirconium, and palladium. Catalysts that displayed the highest activity included a zirconia and silicon-titanium oxide promoted Cu/Zn/Al2O3 catalyst. Alternative method of catalyst preparation, include the oxalate-gel, solid-state reaction, co-precipitation and combustion method also investigated.  © 2013 BCREC UNDIP. All rights reservedReceived: 10th October 2012; Revised: 7th February 2012; Accepted: 10th February 2013[How to Cite: Young, A., Lesmana, D., Dai, D.J., Wu, H.S. (2013. Short Review: Mitigation of Current En-vironmental Concerns from Methanol Synthesis. Bulletin of Chemical Reaction Engineering & Catalysis, 8 (1: 1-13. (doi:10.9767/bcrec.8.1.4055.1-13][Permalink/DOI: http://dx.doi.org/10.9767/bcrec.8.1.4055.1-13] | View in  |

  5. Model studies of methanol synthesis on copper catalysts

    Energy Technology Data Exchange (ETDEWEB)

    Nakamura, J.; Nakamura, I.; Uchijima, T. [Univ. of Tsukuba, Ibaraki (Japan); Watanabe, T. [Research Inst. of Innovative Technology for Earth, Kyoto (Japan); Fujitani, T. [National Inst. for Resources and Environment, Ibaraki (Japan)

    1996-12-31

    The synthesis of methanol by the hydrogenation of CO{sub 2} over Zn-deposited and Zn-free copper surfaces has been studied using an XPS apparatus combined with a high-pressure flow reactor (18 atm). It was shown that the Zn deposited on Cu(111) and poly-Cu acted as a promoter for methanol synthesis, while the Zn on Cu(110) and Cu(100) had no such a promotional effect. The turnover frequency (TOF) for Zn/Cu(111) linearly increased with Zn coverage below {Theta}Zn--0.19, and then decreased above {Theta}Zn=0.20. The optimum TOF obtained at {Theta}Zn--0-19 was thirteen-fold larger than TOF for the Zn-free Cu(111) surface. On the other hand, no promotional effect of Zn was observed for the reverse water-gas shift reaction on all the surfaces. The results indicate the formation of special sites for methanol synthesis on Zn/Cu(111). The Zn-deposited Cu(111) can be regarded as a model of Cu/ZnO catalysts because the TOF and the activation energy for methanol formation over the Zn-deposited Cu(111) were in fairly good agreement with those for the Cu/ZnO powder catalysts. The post-reaction surface analysis by XPS showed the formation of formate species (HCOOa). The formate coverage was proportional to the activity for methanol formation below {Theta}Zn=0.20, suggesting that the hydrogenation of the formate species is the rate-determining step of methanol formation. The formate species was stabilized by Zn species on Cu(111) in the absence of ZnO species. STM results on the Zn-deposited Cu(111) suggested the formation of a Cu-Zn surface alloy. The presence of special sites for methanol synthesis was also indicated in the results of powder catalysts.

  6. Green synthesis of Ni-Nb oxide catalysts for low-temperature oxidative dehydrogenation of ethane.

    Science.gov (United States)

    Zhu, Haibo; Rosenfeld, Devon C; Anjum, Dalaver H; Caps, Valérie; Basset, Jean-Marie

    2015-04-13

    The straightforward solid-state grinding of a mixture of Ni nitrate and Nb oxalate crystals led to, after mild calcination (Tethane to ethylene at a relatively low temperature (Tethane. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  7. Low-temperature synthesis of 2D MoS2 on a plastic substrate for a flexible gas sensor.

    Science.gov (United States)

    Zhao, Yuxi; Song, Jeong-Gyu; Ryu, Gyeong Hee; Ko, Kyung Yong; Woo, Whang Je; Kim, Youngjun; Kim, Donghyun; Lim, Jun Hyung; Lee, Sunhee; Lee, Zonghoon; Park, Jusang; Kim, Hyungjun

    2018-05-08

    The efficient synthesis of two-dimensional molybdenum disulfide (2D MoS2) at low temperatures is essential for use in flexible devices. In this study, 2D MoS2 was grown directly at a low temperature of 200 °C on both hard (SiO2) and soft substrates (polyimide (PI)) using chemical vapor deposition (CVD) with Mo(CO)6 and H2S. We investigated the effect of the growth temperature and Mo concentration on the layered growth by Raman spectroscopy and microscopy. 2D MoS2 was grown by using low Mo concentration at a low temperature. Through optical microscopy, Raman spectroscopy, X-ray photoemission spectroscopy, photoluminescence, and transmission electron microscopy measurements, MoS2 produced by low-temperature CVD was determined to possess a layered structure with good uniformity, stoichiometry, and a controllable number of layers. Furthermore, we demonstrated the realization of a 2D MoS2-based flexible gas sensor on a PI substrate without any transfer processes, with competitive sensor performance and mechanical durability at room temperature. This fabrication process has potential for burgeoning flexible and wearable nanotechnology applications.

  8. Green synthesis of Ni-Nb oxide catalysts for low-temperature oxidative dehydrogenation of ethane

    KAUST Repository

    Zhu, Haibo

    2015-03-05

    The straightforward solid-state grinding of a mixture of Ni nitrate and Nb oxalate crystals led to, after mild calcination (T<400°C), nanostructured Ni-Nb oxide composites. These new materials efficiently catalyzed the oxidative dehydrogenation (ODH) of ethane to ethylene at a relatively low temperature (T<300°C). These catalysts appear to be much more stable than the corresponding composites prepared by other chemical methods; more than 90% of their original intrinsic activity was retained after 50h with time on-stream. Furthermore, the stability was much less affected by the Nb content than in composites prepared by classical "wet" syntheses. These materials, obtained in a solvent-free way, are thus promising green and sustainable alternatives to the current Ni-Nb candidates for the low-temperature ODH of ethane.

  9. Low temperature synthesis and photoluminescence study of Y2Ti2O7:Eu nanoparticles

    International Nuclear Information System (INIS)

    Selvi, E.; Prasad, A.I.; Nigam, Sandeep; Sudarsan, V.; Vatsa, R.K.

    2014-01-01

    Very small nanoparticles both undoped and doped Y 2 Ti 2 O 7 were prepared at a low temperature (700℃). The obtained undoped and doped Y 2 Ti 2 O 7 samples exhibit good crystallinity, smaller average crystallite size. Based on the detailed luminescence studies, it is confirmed that the lanthanide doped nano-materials have improved luminescence properties compared to the corresponding bulk samples. (author)

  10. Direct synthesis of multi-layer graphene film on various substrates by microwave plasma at low temperature

    Energy Technology Data Exchange (ETDEWEB)

    Park, Hyun Jae [Plasma Technology Research Center, 814-2 Osickdo-dong (SGFEZ), Gunsan, Jeollabuk-do 573-540 (Korea, Republic of); Ahn, Byung Wook; Kim, Tae Yoo; Lee, Jung Woo [School of Advanced Materials Science and Engineering, Advanced Materials and Process Research Center (AMPRC), Sungkyunkwan University, Suwon 440-746 (Korea, Republic of); Jung, Yong Ho; Choi, Yong Sup [Plasma Technology Research Center, 814-2 Osickdo-dong (SGFEZ), Gunsan, Jeollabuk-do 573-540 (Korea, Republic of); Song, Young Il, E-mail: physein01@skku.edu [School of Advanced Materials Science and Engineering, Advanced Materials and Process Research Center (AMPRC), Sungkyunkwan University, Suwon 440-746 (Korea, Republic of); Suh, Su Jeong, E-mail: suhsj@skku.edu [School of Advanced Materials Science and Engineering, Advanced Materials and Process Research Center (AMPRC), Sungkyunkwan University, Suwon 440-746 (Korea, Republic of)

    2015-07-31

    We introduce a possible route for vertically standing multi-layer graphene films (VMGs) on various substrates at low temperature by electron cyclone resonance microwave plasma. VMG films on various substrates, including copper sheet, glass and silicon oxide wafer, were analyzed by studying their structural, electrical, and optical properties. The density and temperature of plasma were measured using Cylindrical Langmuir probe analysis. The morphologies and microstructures of multi-layer graphene were characterized using field emission scattering electron microscope, high resolution transmission electron microscope, and Raman spectra measurement. The VMGs on different substrates at the same experimental conditions synthesized the wrinkled VMGs with different heights. In addition, the transmittance and electrical resistance were measured using ultra-violet visible near-infrared spectroscopy and 4 probe point surface resistance measurement. The VMGs on glass substrate obtained a transmittance of 68.8% and sheet resistance of 796 Ω/square, whereas the VMGs on SiO{sub 2} wafer substrate showed good sheet resistance of 395 Ω/square and 278 Ω/square. The results presented herein demonstrate a simple method of synthesizing of VMGs on various substrates at low temperature for mass production, in which the VMGs can be used in a wide range of application fields for energy storage, catalysis, and field emission due to their unique orientation. - Highlights: • We present for synthesis method of graphene at low temperature on various substrates. • We grow the graphene films at low temperature under of 432 °C. • Structural information of graphene films were studied upon Raman spectroscopy. • Inter-layer spacing of vertically standing graphene relies on synthesis time. • We measured a transmittance and a resistance for graphene films on difference substrate.

  11. Low Temperature Synthesis of Li2SiO3: Effect on Its Morphological and Textural Properties

    Directory of Open Access Journals (Sweden)

    Georgina Mondragón-Gutiérrez

    2008-01-01

    Full Text Available Synthesis, at low temperature, of Li2SiO3 was investigated using different Li : Si molar ratios and urea, which was used as template. This new synthesis was performed in order to look for different textural and morphological properties than those obtained usually by conventional methods in this kind of ceramics. XRD and SEM analyses showed that Li2SiO3 was obtained pure and with ceramic particle morphology of hollow spheres of 2–6 μm. TEM analysis showed that those spheres were composed by needle-like particles crosslinked among them. This morphology provided a high surface area, probed by N2 adsorption. Therefore, this method of synthesis may be used to obtain other similar ceramics and test them in different applications.

  12. Low Temperature Graphene Synthesis from Poly(methyl methacrylate) Using Microwave Plasma Treatment

    Science.gov (United States)

    Yamada, Takatoshi; Ishihara, Masatou; Hasegawa, Masataka

    2013-11-01

    A graphene film having low sheet resistance (600 Ω/sq.) was synthesized at low temperatures of 280 °C. Utilizing microwave plasma treatment, graphene films were synthesized from a solid phase on a copper surface. The full width at half maximum of the 2D-band in the Raman spectrum indicated that a high quality graphene film was formed. Cross-sectional transmission electron microscopy observation revealed that the deposited graphene films consisted of single- or double-layer graphene flakes of nanometer order on the Cu surface, which agrees with the estimated number of layers from an average optical transmittance of 96%.

  13. Low temperature synthesis, magnetic and electrical properties of iron-magnesium superparamagnetic nanoalloy

    Energy Technology Data Exchange (ETDEWEB)

    Nazir, Rabia [Department of Chemistry, Quaid-i-Azam University, Islamabad 45320 (Pakistan); Mazhar, Muhammad [Department of Chemistry, Quaid-i-Azam University, Islamabad 45320 (Pakistan)], E-mail: mazhar42pk@yahoo.com; Akhtar, Muhammad Javed; Nadeem, Muhammad; Siddique, Muhammad [Physics Division, Pinstech, P.O. Nilore, Islamabad (Pakistan); Shah, Raza [HEJ Research Institute of Chemistry, University of Karachi, Karachi 75270 (Pakistan); Hasanain, S. Khurshid [Department of Physics, Quaid-i-Azam University, Islamabad 45320 (Pakistan)

    2009-06-24

    A low temperature chemical approach which beats the miscibility barrier of Fe and Mg has been designed to synthesize Fe-Mg{sub 2} nanoalloy and tested to result nanoparticles of average 30 nm size. The nanoalloy is amorphous in nature and characterized by XPRD, AFM, magnetometery, Moessbauer and impedance spectroscopies. The result of magnetic measurement suggests the sample to be superparamagnetic as evidenced by the {sup 57}Fe Moessbauer spectroscopy. The two Mg atoms occupy different positions around iron resulting in two phase system as shown by Moessbauer and impedance spectroscopies.

  14. Low temperature synthesis, magnetic and electrical properties of iron-magnesium superparamagnetic nanoalloy

    International Nuclear Information System (INIS)

    Nazir, Rabia; Mazhar, Muhammad; Akhtar, Muhammad Javed; Nadeem, Muhammad; Siddique, Muhammad; Shah, Raza; Hasanain, S. Khurshid

    2009-01-01

    A low temperature chemical approach which beats the miscibility barrier of Fe and Mg has been designed to synthesize Fe-Mg 2 nanoalloy and tested to result nanoparticles of average 30 nm size. The nanoalloy is amorphous in nature and characterized by XPRD, AFM, magnetometery, Moessbauer and impedance spectroscopies. The result of magnetic measurement suggests the sample to be superparamagnetic as evidenced by the 57 Fe Moessbauer spectroscopy. The two Mg atoms occupy different positions around iron resulting in two phase system as shown by Moessbauer and impedance spectroscopies.

  15. Tailoring Cu Nanoparticle Catalyst for Methanol Synthesis Using the Spinning Disk Reactor

    Directory of Open Access Journals (Sweden)

    Christian Ahoba-Sam

    2018-01-01

    Full Text Available Cu nanoparticles are known to be very active for methanol (MeOH synthesis at relatively low temperatures, such that smaller particle sizes yield better MeOH productivity. We aimed to control Cu nanoparticle (NP size and size distribution for catalysing MeOH synthesis, by using the spinning disk reactor. The spinning disk reactor (SDR, which operates based on shear effect and plug flow in thin films, can be used to rapidly micro-mix reactants in order to control nucleation and particle growth for uniform particle size distribution. This could be achieved by varying both physical and chemical operation conditions in a precipitation reaction on the SDR. We have used the SDR for a Cu borohydride reduction to vary Cu NP size from 3 nm to about 55 nm. XRD and TEM characterization confirmed the presence of Cu2O and Cu crystallites when the samples were dried. This technique is readily scalable for Cu NP production by processing continuously over a longer duration than the small-scale tests. However, separation of the nanoparticles from solution posed a challenge as the suspension hardly settled. The Cu NPs produced were tested to be active catalyst for MeOH synthesis at low temperature and MeOH productivity increased with decreasing particle size.

  16. Synthesis of Highly Uniform and Compact Lithium Zinc Ferrite Ceramics via an Efficient Low Temperature Approach.

    Science.gov (United States)

    Xu, Fang; Liao, Yulong; Zhang, Dainan; Zhou, Tingchuan; Li, Jie; Gan, Gongwen; Zhang, Huaiwu

    2017-04-17

    LiZn ferrite ceramics with high saturation magnetization (4πM s ) and low ferromagnetic resonance line widths (ΔH) represent a very critical class of material for microwave ferrite devices. Many existing approaches emphasize promotion of the grain growth (average size is 10-50 μm) of ferrite ceramics to improve the gyromagnetic properties at relatively low sintering temperatures. This paper describes a new strategy for obtaining uniform and compact LiZn ferrite ceramics (average grains size is ∼2 μm) with enhanced magnetic performance by suppressing grain growth in great detail. The LiZn ferrites with a formula of Li 0.415 Zn 0.27 Mn 0.06 Ti 0.1 Fe 2.155 O 4 were prepared by solid reaction routes with two new sintering strategies. Interestingly, results show that uniform, compact, and pure spinel ferrite ceramics were synthesized at a low temperature (∼850 °C) without obvious grain growth. We also find that a fast second sintering treatment (FSST) can further improve their gyromagnetic properties, such as higher 4πM s and lower ΔH. The two new strategies are facile and efficient for densification of LiZn ferrite ceramics via suppressing grain growth at low temperatures. The sintering strategy reported in this study also provides a referential experience for other ceramics, such as soft magnetism ferrite ceramics or dielectric ceramics.

  17. Electro-hydrodynamic spray synthesis and low temperature spectroscopic characterization of Perovskite thin films

    Science.gov (United States)

    Sarang, Som; Ishihara, Hidetaka; Tung, Vincent; Ghosh, Sayantani

    Utilizing a Marangoni flow inspired electrospraying technique, we synthesize hybrid perovskite (PVSK) thin films with broad absorption spectrum and high crystallinity. The precursor solvents are electrosprayed onto an indium tin oxide (ITO) substrate, resulting in a gradient force developing between the droplet surface and the bulk due to the varying vapor pressure in the bi-solvent system. This gradient force helps the droplets propagate and merge with surrounding ones, forming a uniform thin film with excellent morphological and topological characteristics, as evident from the average power conversion efficiency (PCE) of 16%. In parallel, we use low temperature static and dynamic photoluminescence spectroscopy to probe the grain boundaries and defects in the synthesized PVSK thin films. At 120 K, the emergence of the low temperature orthorhombic phase is accompanied by reduction in lifetimes by an order of magnitude, a result attributed to charge transfer between the orthorhombic and tetragonal domains, as well as due to a crossover from free charge carrier to excitonic recombination. Our fabrication technique and optical studies help in advancement of PVSK based technology by providing unique insights into the fundamental physics of these novel materials. This research was supported by National Aeronautics and Space administration (NASA) Grant No: NNX15AQ01A.

  18. A handheld low temperature atmospheric pressure air plasma gun for nanomaterial synthesis in liquid phase

    Energy Technology Data Exchange (ETDEWEB)

    Yu, Shuang; Wang, Kaile; Zuo, Shasha; Liu, Jiahui [Academy for Advanced Interdisciplinary Studies, Peking University, Beijing 100871 (China); Zhang, Jue, E-mail: zhangjue@pku.edu.cn; Fang, Jing [Academy for Advanced Interdisciplinary Studies, Peking University, Beijing 100871 (China); College of Engineering, Peking University, Beijing 100871 (China)

    2015-10-15

    A handheld low temperature atmospheric pressure air plasma gun based on a dielectric barrier structure with hollow electrodes was proposed. The portable plasma gun with an embedded mini air pump was driven by a 12 V direct voltage battery. The air plasma jet generated from the gun could be touched without a common shock hazard. Besides working in air, the plasma gun can also work in water. The diagnostic result of optical emission spectroscopy showed the difference in reactive species of air plasma jet between in air and in water. The plasma gun was excited in 20 ml chloroauric acid aqueous solution with a concentration of 1.214 mM. A significant amount of gold nanoparticles were synthesized after 2 min continuous discharge. The plasma gun with these unique features is applicable in plasma medicine, etching, and s-nthesis of nanomaterials.

  19. Ultrafine ferromagnetic iron oxide nanoparticles: Facile synthesis by low temperature decomposition of iron glycerolate

    Energy Technology Data Exchange (ETDEWEB)

    Bartůněk, Vilém, E-mail: vilem.bartunek@vscht.cz [Department of Inorganic Chemistry, Faculty of Chemical Technology, University of Chemistry and Technology, Technická 5, 166 28 Prague 6 (Czech Republic); Průcha, David [Department of Inorganic Chemistry, Faculty of Chemical Technology, University of Chemistry and Technology, Technická 5, 166 28 Prague 6 (Czech Republic); Švecová, Marie [Department of Analytical Chemistry, Faculty of Chemical Engineering, University of Chemistry and Technology, Technická 5, 166 28 Prague 6 (Czech Republic); Ulbrich, Pavel [Department of Biochemistry and Microbiology, Faculty of Food and Biochemical Technology, University of Chemistry and Technology, Technická 3, 166 28 Prague 6 (Czech Republic); Huber, Štěpán; Sedmidubský, David; Jankovský, Ondřej [Department of Inorganic Chemistry, Faculty of Chemical Technology, University of Chemistry and Technology, Technická 5, 166 28 Prague 6 (Czech Republic)

    2016-09-01

    We synthesized dark colored ultrafine – sub 10 nm iron oxide nanoparticles by a facile and low temperature process based on thermal decomposition of an affordable precursor – iron glycerolate. Simultaneous thermal analysis (STA) was used to study the thermal behaviour during the decomposition. The iron glycerolate was thoroughly analysed by various methods. The size of the iron nanoparticles was determined from XRD patterns and by transmission electron microscopy (TEM) and their composition has been confirmed by XPS. Magnetic properties of the nanoparticles were studied by vibrating sample magnetometry. The prepared single phase material exhibiting ferromagnetic properties is usable in a wide range of applications and may be suitable even for large scale industrial applications. - Highlights: • Iron glycerolate prepared and characterised. • Iron oxide nanoparticles prepared by thermal decomposition of iron glycerolate. • STA used to study the decomposition. • Products characterised by XRD, XPS, FT-IR, SEM and TEM. • Magnetic behaviour of monophasic samples determined.

  20. Low temperature synthesis of coiled carbon nanotubes and their magnetic properties

    Science.gov (United States)

    Krishna, Vemula Mohana; Somanathan, T.; Manikandan, E.

    2018-04-01

    In this paper, coiled like structure of carbon nanotubes (c-CNTs) have been effectively grown on bi-metal substituted α-alumina nanoparticles catalyst by chemical vapor deposition (CVD) system. Highly graphitized and dense bundles of carbon product were attained at a low temperature of 550 °C. The coiled carbon nanostructures in very longer lengths were noticed by field emission scanning electron microscope (FESEM) observation. Furthermore, high purity material was achieved, which correlates the energy dispersive x-ray spectroscopy (EDX) analysis. High resolution transmission electron microscope (HRTEM) revealed the diameter and graphitization of coiled structures. The superparamagnetic like behavior was observed at room temperature for the as-synthesized product, which was found by VSM investigation.

  1. Synthesis and characterization of L-tyrosine hydrochloride crystals submitted to high and low temperatures

    Energy Technology Data Exchange (ETDEWEB)

    Santos, C.A.A.S.; Facanha Filho, P.F.; Ribeiro, L.H.L.; Victor, F.M.S.; Abreu, D.C.; Santos, A.O. dos; Carvalho, J.O.; Soares, R.A.; Sousa, J.C.F.; Lima, R.C.; Cavaignac, A.O. [Universidade Federal do Maranhao (UFMA), MA (Brazil)

    2016-07-01

    Full text: New materials are emerging and generate advances in nonlinear optics that studies the phenomena related to changes in optical properties when occurs interaction of light with the matter. Semi organic crystals present such properties. The goal is this work is to produce semi organic single crystal of L-tyrosine hydrochloride (LTHCl) and verify their thermal stability when subjected to high and low temperatures. The single crystals of LTHCl were produced for solubilization of amino acid L-tyrosine in hydrochloric acid using slow solvent evaporation technique at a constant temperature of 25 deg C. The X-ray diffraction (XRD) and refining by the Rietveld method were used to confirm the structure of the material. The thermal stability was investigated using DSC, TGA-DTA. The LTHCl crystal belongs to the monoclinic system, with two molecules per unit cell. The refinement by the Rietveld method showed good results with Rwp= 8.49% and Rp= 6.29% with S=1.13. Thermal analysis shown an endothermic event at about 160°C, which can be associated with phase transition occurred in LTHCl crystal. It was also observed that the crystal melting point occurs at a temperature of 230°C. No water of crystallization was found in the crystal structure, which was confirmed by Raman spectroscopy and thermal analysis. From the Raman spectroscopy experiments in function of temperature, no significant changes was observe in the behavior of vibrational normal modes between temperatures of -253 and 170 deg C. Finally, a monoclinic crystal system LTHCl is stable up to 160°C at high temperatures and -253°C at low temperatures. Therefore, our investigation has proved that LTHCl crystals can be used in this range of temperature without the lost of their nonlinear optical properties. (author)

  2. Low temperature synthesis of Mo2C/W2C superlattices via ultra-thin modulated reactants

    International Nuclear Information System (INIS)

    Johnson, C.D.; Johnson, D.C.

    1996-01-01

    The authors report here a synthesis method of preparing carbide superlattices using ultra-thin modulated reactants. Initial investigations into the synthesis of the binary systems, Mo 2 C and W 2 C using ultra-thin modulated reactants revealed that both can be formed at relatively low temperatures (500 and 600 C respectively). DSC and XRD data suggested a two step reaction pathway involving interdiffusion of the initial modulated reactant followed by crystallization of the final product, if the modulation length is on the order of 10 angstrom. This information was used to form Mo 2 C/W 2 C superlattices using the structure of the ultra-thin modulated reactant to control the final superlattice period. Relatively large superlattice modulations were kinetically trapped by having several repeat units of each binary within the total repeat of the initial reactant. DSC and XRD data again are consistent with a two step reaction pathway leading to the formation of carbide superlattices

  3. Low temperature synthesis of silicon quantum dots with plasma chemistry control in dual frequency non-thermal plasmas.

    Science.gov (United States)

    Sahu, Bibhuti Bhusan; Yin, Yongyi; Han, Jeon Geon; Shiratani, Masaharu

    2016-06-21

    The advanced materials process by non-thermal plasmas with a high plasma density allows the synthesis of small-to-big sized Si quantum dots by combining low-temperature deposition with superior crystalline quality in the background of an amorphous hydrogenated silicon nitride matrix. Here, we make quantum dot thin films in a reactive mixture of ammonia/silane/hydrogen utilizing dual-frequency capacitively coupled plasmas with high atomic hydrogen and nitrogen radical densities. Systematic data analysis using different film and plasma characterization tools reveals that the quantum dots with different sizes exhibit size dependent film properties, which are sensitively dependent on plasma characteristics. These films exhibit intense photoluminescence in the visible range with violet to orange colors and with narrow to broad widths (∼0.3-0.9 eV). The observed luminescence behavior can come from the quantum confinement effect, quasi-direct band-to-band recombination, and variation of atomic hydrogen and nitrogen radicals in the film growth network. The high luminescence yields in the visible range of the spectrum and size-tunable low-temperature synthesis with plasma and radical control make these quantum dot films good candidates for light emitting applications.

  4. Low temperature synthesis of carbon encapsulated Fe7S8 nanocrystals as high performance anode for lithium-ion batteries

    International Nuclear Information System (INIS)

    Liu, Boyang; Zhang, Fuhua; Wu, Qianlin; Wang, Junhua; Li, Wenge; Dong, Lihua; Yin, Yansheng

    2015-01-01

    A novel method is developed for low temperature synthesis of carbon encapsulated spherical Fe 7 S 8 nanocrystals with core–shell structure (Fe 7 S 8 @C) by the reaction of ferrocene with ammonium persulphate. The phase structure, morphology, specific surface area and composition of the nanocomposite are systematically characterized. It is found that the Fe 7 S 8 nanocrystals with a weight percent of 33.5% have a median size of 25.2 nm. The Fe 7 S 8 @C electrodes retain a reversible capacity of 815 and 539 mAh g −1 after 50 cycles at a current density of 200 and 2284 mA g −1 , respectively. The high capacity, good cycling behavior and rate capability of Fe 7 S 8 @C electrodes are attributed to the good protection and electrical conductivity of carbon shell. - Highlights: • Large scale and low temperature synthesis of Fe 7 S 8 @C with core–shell structure. • The Fe 7 S 8 @C electrodes retain a capacity of 815 mAh g −1 after 50 cycles at 200 mA g −1 . • The Fe 7 S 8 @C electrodes show good cycling behavior and rate capability

  5. Low temperature synthesis of nanosized Mn1–xZnxFe2O4 ferrites ...

    Indian Academy of Sciences (India)

    Administrator

    spectrum analysis were carried out to confirm the spinel phase formation as well as to ascertain the cation distri- bution in the ferrite ... structured materials technology opening up in the last few ... recent years, the design and synthesis of nano-magnetic particles ..... complex system like the ferrites where many cations are.

  6. Low temperature synthesis of ternary metal phosphides using plasma for asymmetric supercapacitors

    KAUST Repository

    Liang, Hanfeng

    2017-04-06

    We report a versatile route for the preparation of metal phosphides using PH plasma for supercapacitor applications. The high reactivity of plasma allows rapid and low temperature conversion of hydroxides into monometallic, bimetallic, or even more complex nanostructured phosphides. These same phosphides are much more difficult to synthesize by conventional methods. Further, we present a general strategy for significantly enhancing the electrochemical performance of monometallic phosphides by substituting extrinsic metal atoms. Using NiCoP as a demonstration, we show that the Co substitution into NiP not only effectively alters the electronic structure and improves the intrinsic reactivity and electrical conductivity, but also stabilizes Ni species when used as supercapacitor electrode materials. As a result, the NiCoP nanosheet electrodes achieve high electrochemical activity and good stability in 1 M KOH electrolyte. More importantly, our assembled NiCoP nanoplates//graphene films asymmetric supercapacitor devices can deliver a high energy density of 32.9 Wh kg at a power density of 1301 W kg, along with outstanding cycling performance (83% capacity retention after 5000 cycles at 20 A g). This activity outperforms most of the NiCo-based materials and renders the NiCoP nanoplates a promising candidate for capacitive storage devices.

  7. Low-temperature molten salt synthesis and characterization of CoWO4 nano-particles

    International Nuclear Information System (INIS)

    Song Zuwei; Ma Junfeng; Sun Huyuan; Sun Yong; Fang Jingrui; Liu Zhengsen; Gao Chang; Liu Ye; Zhao Jingang

    2009-01-01

    CoWO 4 nano-particles were successfully synthesized at a low temperature of 270 deg. C by a molten salt method, and effects of such processing parameters as holding time and salt quantity on the crystallization and development of CoWO 4 crystallites were initially studied. The products were characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), and photoluminescent spectra techniques (PL), respectively. Experimental results showed that the well-crystallized CoWO 4 nano-particles with ca. 45 nm in diameter could be obtained at 270 deg. C for a holding time of 8 h with 6:1 mass ratio of the salt to CoWO 4 precursor, and XRD analysis evidenced that the as-prepared sample was a pure monoclinic phase of CoWO 4 with wolframite structure. Their PL spectra revealed that the CoWO 4 nano-particles displayed a very strong PL peak at 453 nm with the excitation wavelength of 230 nm, and PL properties of CoWO 4 crystallites relied on their crystalline state, especially on their particle size.

  8. MgO:Eu3+ red nanophosphor: Low temperature synthesis and photoluminescence properties

    Science.gov (United States)

    Devaraja, P. B.; Avadhani, D. N.; Prashantha, S. C.; Nagabhushana, H.; Sharma, S. C.; Nagabhushana, B. M.; Nagaswarupa, H. P.; Premkumar, H. B.

    2014-03-01

    Nanoparticles of Eu3+ doped (0-9 mol%) MgO were prepared using low temperature (400 °C) solution combustion technique with metal nitrate as precursor and glycine as fuel. The powder X-ray diffraction (PXRD) patterns of the as-formed products show single cubic phase and no further calcination was required. The crystallite size was obtained using Scherer's formula and was found to be 5-6 nm. The effect of Eu3+ ions on luminescence characteristics of MgO was studied and the results were discussed in detail. These phosphors exhibit bright red emission upon 395 nm excitation. The characteristic photoluminescence (PL) emission peaks at ∼580, 596, 616, 653, 696 and 706 nm (5D0 → 7Fj= 0, 1, 2, 3, 4) were recorded due to Eu3+ ions. The electronic transition corresponding to 5D0 → 7F2 of Eu3+ ions (616 nm) was stronger than the magnetic dipole transition corresponding to 5D0 → 7F1 of Eu3+ ions (596 nm). The international commission on illumination (CIE) chromaticity co-ordinates were calculated from emission spectra, the values (x, y) were very close to national television system committee (NTSC) standard value of red emission. Therefore the present phosphor was highly useful for display applications.

  9. Low temperature synthesis and electrical characterization of germanium doped Ti-based nanocrystals for nonvolatile memory

    International Nuclear Information System (INIS)

    Feng, Li-Wei; Chang, Chun-Yen; Chang, Ting-Chang; Tu, Chun-Hao; Wang, Pai-Syuan; Lin, Chao-Cheng; Chen, Min-Chen; Huang, Hui-Chun; Gan, Der-Shin; Ho, New-Jin; Chen, Shih-Ching; Chen, Shih-Cheng

    2011-01-01

    Chemical and electrical characteristics of Ti-based nanocrystals containing germanium, fabricated by annealing the co-sputtered thin film with titanium silicide and germanium targets, were demonstrated for low temperature applications of nonvolatile memory. Formation and composition characteristics of nanocrystals (NCs) at various annealing temperatures were examined by transmission electron microscopy and X-ray photon-emission spectroscopy, respectively. It was observed that the addition of germanium (Ge) significantly reduces the proposed thermal budget necessary for Ti-based NC formation due to the rise of morphological instability and agglomeration properties during annealing. NC structures formed after annealing at 500 °C, and separated well at 600 °C annealing. However, it was also observed that significant thermal desorption of Ge atoms occurs at 600 °C due to the sublimation of formatted GeO phase and results in a serious decrease of memory window. Therefore, an approach to effectively restrain Ge thermal desorption is proposed by encapsulating the Ti-based trapping layer with a thick silicon oxide layer before 600 °C annealing. The electrical characteristics of data retention in the sample with the 600 °C annealing exhibited better performance than the 500 °C-annealed sample, a result associated with the better separation and better crystallization of the NC structures.

  10. Low-Temperature Reverse Microemulsion Synthesis, Characterization, and Photocatalytic Performance of Nanocrystalline Titanium Dioxide

    Directory of Open Access Journals (Sweden)

    Zhang Liu

    2012-01-01

    Full Text Available Nanocrystalline titanium dioxide (TiO2 was synthesized in microemulsions by using cetyltrimethylammonium bromide (CTAB as surfactant. In order to investigate the crystal transformation and photoactivity at low temperature, the as-prepared precipitates were aged at 65°C or calcined at various temperatures. Analyses using powder X-ray diffraction (XRD and Fourier transform infrared microscopy (FT-IR showed that precursors without aging or calcination were noncrystal and adsorbed by surfactant. After aging for 6 h, the amorphous TiO2 began to change into anatase. The obtained catalysts, which were synthesized in microemulsions with weight ratios of n-hexanol/CTAB/water as 6 : 3 : 1 and calcined at 500°C, presented the highest photocatalytic degradation rate on methyl orange (MO, while the catalysts, which were aged at 65°C for 90 h, also exhibited an outstanding photocatalytic performance and a little higher than that of the commercial titania photocatalyst Degussa P25.

  11. Nanocellulose-assisted low-temperature synthesis and supercapacitor performance of reduced graphene oxide aerogels

    Science.gov (United States)

    Wang, Jie; Ran, Ran; Sunarso, Jaka; Yin, Chao; Zou, Honggang; Feng, Yi; Li, Xiaobao; Zheng, Xu; Yao, Jianfeng

    2017-04-01

    Here, we have synthesized reduced graphene oxide (rGO) aerogels using a nanocellulose-assisted low temperature (less than 500 °C) thermal treatment route where nanocelluloses promote the gelation of graphene oxide (GO) solution that benefits the fabrication of GO aerogels from low concentration dispersion (2.85 mg mL-1), and after their thermal decomposition the residual nanofibers act as spacer both prevent the re-stacking of graphene sheets and integrate with rGO sheets to give a particular kind of carbon-based aerogel along with numerous defects (holes). Thermal decomposition of nanocellulose appears to be complete beyond 350 °C thus its presence in form of amorphous carbon nanofibers in rGO sheets. The rGO aerogels synthesized at 350 °C provide the best balance in terms of wide interlayer spacing, high content of CO-type functional groups, and high defects content. This translates into a high discharge capacitance of 270 F g-1 at a current rate of 1 A g-1 for compressed rGO aerogels without any binder or conductive additive. Detailed electrochemical tests using 6 M KOH electrolyte establish the fact that pseudocapacitance component has substantial contribution towards the overall capacitance; closely approaching the contribution of the double layer capacitance that is the most dominant capacitance component.

  12. Low-temperature synthesis of superconducting nanocrystalline MgB2

    International Nuclear Information System (INIS)

    Lu, J.; Xiao, Z.; Lin, Q.; Claus, H.; Fang, Z.Z.

    2010-01-01

    Magnesium diboride (MgB 2 ) is considered a promising material for practical application in superconducting devices, with a transition temperature near 40 K. In the present paper, nanocrystalline MgB 2 with an average particle size of approximately 70 nm is synthesized by reacting LiBH 4 with MgH 2 at temperatures as low as 450 C. This synthesis approach successfully bypasses the usage of either elemental boron or toxic diborane gas. The superconductivity of the nanostructures is confirmed by magnetization measurements, showing a superconducting critical temperature of 38.7 K.

  13. A Versatile Route for the Synthesis of Nickel Oxide Nanostructures Without Organics at Low Temperature

    Directory of Open Access Journals (Sweden)

    Shah MA

    2008-01-01

    Full Text Available AbstractNickel oxide nanoparticles and nanoflowers have been synthesized by a soft reaction of nickel powder and water without organics at 100 °C. The mechanism for the formation of nanostructures is briefly described in accordance with decomposition of metal with water giving out hydrogen. The structure, morphology, and the crystalline phase of resulting nanostructures have been characterized by various techniques. Compared with other methods, the present method is simple, fast, economical, template-free, and without organics. In addition, the approach is nontoxic without producing hazardous waste and could be expanded to provide a general and convenient strategy for the synthesis of nanostructures to other functional nanomaterials.

  14. Low Temperature Synthesis and Properties of Gadolinium-Doped Cerium Oxide Nanoparticles

    DEFF Research Database (Denmark)

    Machado, M. F. S.; Moraes, L. P. R.; Monteiro, N. K.

    2017-01-01

    Gadolinium-doped cerium oxide (GDC) is an attractive ceramic material for solid oxide fuel cells (SOFCs) both as the electrolyte and in composite electrodes operating at low and intermediate temperatures. GDC exhibits high oxygen ion conductivity at a wide range of temperatures and displays a high...... resistance to carbon deposition when hydrocarbons are used as fuels. However, an inconvenience of ceria-based oxides is the high sintering temperature needed to obtain a fully dense ceramic body. In this study, a green chemistry route for the synthesis of 10 mol% GDC nanoparticles is proposed. The aqueous...

  15. ISOBUTANOL-METHANOL MIXTURES FROM SYNTHESIS GAS

    Energy Technology Data Exchange (ETDEWEB)

    Enrique Iglesia

    1998-09-01

    Isobutanol is potential as a fuel additive or precursor to methyl tert-butyl ether (MTBE). Alkali-promoted Cu/ZnO/Al{sub 2}O{sub 3} and Cu/MgO/CeO{sub 2} materials have been found to catalyze the formation of isobutanol from CO and H{sub 2} at temperatures (573-623 K) that allow their use in slurry reactors. Our studies focus on the mechanism and structural requirements for selective isobutanol synthesis on these types of catalysts. Alkali promoted Cu/MgO/CeO{sub 2}, Cu/MgO/ZnO, and CuZnAlO{sub x} materials and their individual components Cu/MgO, MgO/CeO{sub 2}, MgO and CeO{sub 2} have been prepared for the use in kinetic studies of alcohol coupling reactions, in identification of reaction intermediates, and in isobutanol synthesis at high pressures. These samples were prepared by coprecipitation of mixed nitrate solutions with an aqueous solution of KOH (2M) and K{sub 2}CO{sub 3} (1M) at 338 K at a constant pH of 9, except for Cs-Cu/ZnO/Al{sub 2}O{sub 3} at a pH of 7, in a well-stirred thermostated container. The precipitate was filtered, washed thoroughly with dioinized water at 303 K in order to remove residual K ions, and dried at 353 K overnight. Dried samples were calcined at 723 K, except for Cs-Cu/ZnO/Al{sub 2}O{sub 3} at 623 K, for 4 h in order to form the corresponding mixed oxides. Alkali addition (K or Cs) was performed by incipient wetness using K{sub 2}CO{sub 3} (0.25 M) and CH{sub 3}COOCs (0.25 M) aqueous solutions. The crystallinity and phase structures of resulting materials were analyzed by powered X-ray diffraction.

  16. Low-temperature synthesis of nanocrystalline ZrC coatings on flake graphite by molten salts

    Energy Technology Data Exchange (ETDEWEB)

    Ding, Jun, E-mail: dingjun@wust.edu.cn; Guo, Ding; Deng, Chengji; Zhu, Hongxi; Yu, Chao

    2017-06-15

    Highlights: • Uniform ZrC coatings are prepared on flake graphite at 900 °C. • ZrC coatings are composed of nanosized (30–50 nm) particles. • The template growth mechanism is believed to be dominant in the molten salt synthesis process. - Abstract: A novel molten salt synthetic route has been developed to prepare nanocrystalline zirconium carbide (ZrC) coatings on flake graphite at 900 °C, using Zr powder and flake graphite as the source materials in a static argon atmosphere, along with molten salts as the media. The effects of different molten salt media, the sintered temperature, and the heat preservation time on the phase and microstructure of the synthetic materials were investigated. The ZrC coatings formed on the flake graphite were uniform and composed of nanosized particles (30–50 nm). With an increase in the reaction temperature, the ZrC nanosized particles were more denser, and the heat preservation time and thickness of the ZrC coating also increased accordingly. Electron microscopy was used to observe the ZrC coatings on the flake graphite, indicating that a “template mechanism” played an important role during the molten salt synthesis.

  17. Low Temperature Solid-State Synthesis and Characterization of LaBO3

    Directory of Open Access Journals (Sweden)

    Azmi Seyhun KIPÇAK

    2016-11-01

    Full Text Available Rare earth (lanthanide series borates, possess high vacuum ultraviolet (VUV transparency, large electronic band gaps, chemical and environmental stability and exceptionally large optical damage thresholds and used in the development of plasma display panels (PDPs. In this study the synthesis of lanthanum borates via solid-state method is studied. For this purpose, lanthanum oxide (La2O3 and boric acid (H3BO3 are used for as lanthanum and boron sources, respectively. Different elemental molar ratios of La to B (between 3:1 to 1:6 as La2O3:H3BO3 were reacted by solid-state method at the reaction temperatures between 500°C - 700°C with the constant reaction time of 4 h. Following the synthesis, characterizations of the synthesized products are conducted by X-ray diffraction (XRD, Fourier transform infrared spectroscopy (FT-IR, Raman spectroscopy and scanning electron microscope (SEM. From the results of the experiments, three types of lanthanum borates of; La3BO6, LaBO3 and La(BO23 were observed at different reaction parameters. Among these three types of lanthanum borates LaBO3 phase were obtained as a major phase.

  18. Cuprous Oxide Scale up: Gram Production via Bulk Synthesis using Classic Solvents at Low Temperatures

    Energy Technology Data Exchange (ETDEWEB)

    Hall, A. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Han, T. Y. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)

    2015-05-07

    Cuprous oxide is a p-type semiconducting material that has been highly researched for its interesting properties. Many small-scale syntheses have exhibited excellent control over size and morphology. As the demand for cuprous oxide grows, the synthesis method need to evolve to facilitate large-scale production. This paper supplies a facile bulk synthesis method for Cu₂O on average, 1-liter reaction volume can produce 1 gram of particles. In order to study the shape and size control mechanisms on such a scale, the reaction volume was diminished to 250 mL producing on average 0.3 grams of nanoparticles per batch. Well-shaped nanoparticles have been synthesized using an aqueous solution of CuCl₂, NaOH, SDS surfactant, and NH₂OH-HCl at mild temperatures. The time allotted between the addition of NaOH and NH₂OH-HCl was determined to be critical for Cu(OH)2 production, an important precursor to the final produce The effects of stirring rates on a large scale was also analyzed during reagent addition and post reagent addition. A morphological change from rhombic dodecahedra to spheres occurred as the stirring speed was increased. The effects of NH₂OH-HCl concentration were also studied to control the etching effects of the final product.

  19. Synthesis and characterization of boron-oxygen-hydrogen thin films at low temperatures

    International Nuclear Information System (INIS)

    Music, D.; Koelpin, H.; Atiser, A.; Kreissig, U.; Bobek, T.; Hadam, B.; Schneider, J.M.

    2005-01-01

    We have studied the influence of synthesis temperature on chemical composition and mechanical properties of X-ray amorphous boron-oxygen-hydrogen (B-O-H) films. These B-O-H films have been synthesized by RF sputtering of a B-target in an Ar atmosphere. Upon increasing the synthesis temperature from room temperature to 550 deg. C, the O/B and H/B ratios decrease from 0.73 to 0.15 and 0.28 to 0.07, respectively, as determined by elastic recoil detection analysis. It is reasonable to assume that potential sources of O and H are residual gas and laboratory atmosphere. The elastic modulus, as measured by nanoindentation, increases from 93 to 214 GPa, as the O/B and H/B ratios decreases within the range probed. Hence, we have shown that the effect of impurity incorporation on the elastic properties is extensive and that the magnitude of the incorporation is a strong function of the substrate temperature

  20. Synthesis and Characterization of Si Oxide Coated Nano Ceria by Hydrolysis, and Hydrothermal Treatment at Low Temperature

    Directory of Open Access Journals (Sweden)

    Kong M.

    2017-06-01

    Full Text Available The purpose of this work was to the application of Si oxide coatings. This study deals with the preparation of ceria (CeO2 nanoparticles coating with SiO2 by water glass and hydrolysis reaction. First, the low temperature hydro-reactions were carried out at 30~100°C. Second, Silicon oxide-coated Nano compounds were obtained by the catalyzing synthesis. CeO2 Nano-powders have been successfully synthesized by means of the hydrothermal method, in a low temperature range of 100~200°C. In order to investigate the structure and morphology of the Nano-powders, scanning electron microscopy (SEM and X-ray diffraction (XRD were employed. The XRD results revealed the amorphous nature of silica nanoparticles. To analyze the quantity and properties of the compounds coated with Si oxide, transmission electron microscopy (TEM in conjunction with electron dispersive spectroscopy was used. Finally, it is suggested that the simple growth process is more favorable mechanism than the solution/aggregation process.

  1. Ab Initio Guided Low Temperature Synthesis Strategy for Smooth Face–Centred Cubic FeMn Thin Films

    Directory of Open Access Journals (Sweden)

    Friederike Herrig

    2018-05-01

    Full Text Available The sputter deposition of FeMn thin films with thicknesses in the range of hundred nanometres and beyond requires relatively high growth temperatures for the formation of the face-centred cubic (fcc phase, which results in high thin film roughness. A low temperature synthesis strategy, based on local epitaxial growth of a 100 nm thick fcc FeMn film as well as a Cu nucleation layer on an α-Al2O3 substrate at 160 °C, enables roughness values (Ra as low as ~0.6 nm, which is in the same order of magnitude as the pristine substrate (~0.1 nm. The synthesis strategy is guided by ab initio calculations, indicating very strong interfacial bonding of the Cu nucleation layer to an α-Al2O3 substrate (work of separation 5.48 J/m²—which can be understood based on the high Cu coordination at the interface—and between fcc FeMn and Cu (3.45 J/m². Accompanied by small lattice misfits between these structures, the strong interfacial bonding is proposed to enable the local epitaxial growth of a smooth fcc FeMn thin film. Based on the here introduced synthesis strategy, the implementation of fcc FeMn based thin film model systems for materials with interface dominated properties such as FeMn steels containing κ-carbide precipitates or secondary phases appears meaningful.

  2. One-pot low-temperature green synthesis of magnetic graphene nanocomposite for the selective reduction of nitrobenzene

    Science.gov (United States)

    Haridas, Vijayasree; Sugunan, Sankaran; Narayanan, Binitha N.

    2018-06-01

    In the present study, a green one-pot low-temperature method is adopted for the synthesis of a novel magnetic graphene nanocomposite catalyst. Graphene preparation is performed without employing any oxidizing agents or corrosive chemicals, under mild sonication in isopropyl alcohol - water mixture. Monolayered nanoplatelets of graphene are obtained in the green solvent mixture and the composite material is found to be ferromagnetic in nature, obvious from the vibrating sample magnetometric measurements. Fe in the nanocomposite exists in two different forms i.e., α-Fe2O3 and α-FeOOH, as evident from the material characterization results. The graphene nanocomposite is found to be highly efficient in the selective reduction of nitrobenzene to aniline under solvent free reaction conditions and magnetic separation of this fine nanomaterial from the reaction mixture is successfully carried out. The catalyst is efficiently reusable till five repeated cycles.

  3. Nanoparticles of Sr(OH)2: synthesis in homogeneous phase at low temperature and application for cultural heritage artefacts

    International Nuclear Information System (INIS)

    Ciliberto, E.; Condorelli, G.G.; La Delfa, S.; Viscuso, E.

    2008-01-01

    This paper concerns the synthesis and the characterization of nanometer particles of Sr(OH) 2 , a moderately high water soluble hydroxide (Ksp=3.2 x 10 -4 at 25 C). The reported process yields strontium hydroxide nanoparticles starting from low cost raw materials in aqueous medium (homogeneous phase) at low temperature (below 100 C) by chemical precipitation from salt solutions, involving very simple operational steps and avoiding the use of organic solvents. Observations by X-ray diffraction (XRD), scanning electron microscopy (SEM), electron dispersive X-Ray (EDX) and Fourier transform infrared spectroscopy (FTIR) indicate that the particles are well-crystallized and have nanometer dimensions (∝30 nm in diameter). Moreover, experimental evidence shows the potential use of this material for the protection and the consolidation of wall paintings (frescoes), paper, stone, wood and other artistic artefacts. (orig.)

  4. Nanoparticles of Sr(OH){sub 2}: synthesis in homogeneous phase at low temperature and application for cultural heritage artefacts

    Energy Technology Data Exchange (ETDEWEB)

    Ciliberto, E.; Condorelli, G.G.; La Delfa, S.; Viscuso, E. [Universita di Catania, Dipartimento di Scienze Chimiche, Catania (Italy)

    2008-07-15

    This paper concerns the synthesis and the characterization of nanometer particles of Sr(OH){sub 2}, a moderately high water soluble hydroxide (Ksp=3.2 x 10{sup -4} at 25 C). The reported process yields strontium hydroxide nanoparticles starting from low cost raw materials in aqueous medium (homogeneous phase) at low temperature (below 100 C) by chemical precipitation from salt solutions, involving very simple operational steps and avoiding the use of organic solvents. Observations by X-ray diffraction (XRD), scanning electron microscopy (SEM), electron dispersive X-Ray (EDX) and Fourier transform infrared spectroscopy (FTIR) indicate that the particles are well-crystallized and have nanometer dimensions ({proportional_to}30 nm in diameter). Moreover, experimental evidence shows the potential use of this material for the protection and the consolidation of wall paintings (frescoes), paper, stone, wood and other artistic artefacts. (orig.)

  5. Low-temperature synthesis of actinide tetraborides by solid-state metathesis reactions

    Science.gov (United States)

    Lupinetti, Anthony J [Los Alamos, NM; Garcia, Eduardo [Los Alamos, NM; Abney, Kent D [Los Alamos, NM

    2004-12-14

    The synthesis of actinide tetraborides including uranium tetraboride (UB.sub.4), plutonium tetraboride (PuB.sub.4) and thorium tetraboride (ThB.sub.4) by a solid-state metathesis reaction are demonstrated. The present method significantly lowers the temperature required to .ltoreq.850.degree. C. As an example, when UCl.sub.4 is reacted with an excess of MgB.sub.2, at 850.degree. C., crystalline UB.sub.4 is formed. Powder X-ray diffraction and ICP-AES data support the reduction of UCl.sub.3 as the initial step in the reaction. The UB.sub.4 product is purified by washing water and drying.

  6. Synthesis and characterization of LiFePO{sub 4} cathode preparation by low temperature method

    Energy Technology Data Exchange (ETDEWEB)

    Rajesh, Desapogu, E-mail: rajesh.desapogu@gmail.com; Srinivas Naik, V.; Sunandana, C.S., E-mail: sunandana@gmail.com

    2015-05-01

    We review in detail the physics and technology of the novel material LiFePO{sub 4}, a potential cathode material for Li-ion batteries. In the present work, nano crystalline LiFePO{sub 4} film has been synthesized in both powder and thin film forms from a non-aqueous sol–gel synthesis route based on oxalates of Li and Fe (II). Ferrous oxalate has been synthesized indigenously using a ferrous sulphate based chemical reaction and characterized. Nano powders and thin films of LiFePO{sub 4} have been fabricated and coated on stainless steel substrates with the aim of device development in future. The material has been characterized extensively by XRD for crystal structure, FESEM for microstructure, EDS for elemental analysis and FTIR for the internal modes of phosphate ion. Fe{sup 3+} impurity characterization has been done by using ESR.

  7. Low temperature synthesis & characterization of lead-free BCZT ceramics using molten salt method

    Science.gov (United States)

    Jai Shree, K.; Chandrakala, E.; Das, Dibakar

    2018-04-01

    Piezoelectric properties are greatly influenced by the synthesis route, microstructure, stoichiometry of the chemical composition, purity of the starting materials. In this study, molten salt method was used to prepare lead-free BCZT ceramics. Molten salt method is one of the simplestmethods to prepare chemically-purified, single phase powders in high yield often at lower temperatures and shorten reaction time. Calcination of the molten salt synthesized powders resulted in asingle-phase perovskite structure at 1000 °C which is ˜ 350 °C less than the conventional solid-sate reaction method. With increasing calcination temperature the average template size was increased (˜ 0.5-2 µm). Formation of well dispersive templates improves the sinterability at lower temperatures. Lead-free BCZT ceramics sintered at 1500 °C for 2 h resulted in homogenous and highly dense microstructure with ˜92% of the theoretical density and a grain size of ˜ 35 µm. This highly dense microstructure could enhance the piezoelectric properties of the system.

  8. Low temperature synthesis of nano alpha-alumina powder by two-step hydrolysis

    International Nuclear Information System (INIS)

    Yan, Ting; Guo, Xiaode; Zhang, Xiang; Wang, Zhixiang; Shi, Jinqiu

    2016-01-01

    Highlights: • The nano α-Al 2 O 3 with good dispersion was prepared by two-step hydrolysis. • α-Al 2 O 3 powders were added as seed particles in the hydrolysis. • This article indicated that the glucose could impel the γ-Al 2 O 3 transformed to α-Al 2 O 3 directly. • This article indicated that the addictive of α-Al 2 O 3 seed could improve the phase transformation rate of γ-Al 2 O 3 to α-Al 2 O 3 . • In this article, the pure α-Al 2 O 3 could be obtained by calcining at 1000 °C for 1.5 h. - Abstract: The ultral fine alpha-alumina powder has been successfully synthesized via two-step hydrolysis of aluminum isopropoxide. Glucose and polyvinyl pyrrolidone were used as surfactants during the appropriate processing step. The alpha-alumina powder was used as seed particles. Several synthesis parameters, such as the amount of seeds, surfactants, and calcination temperature, were studied by X-ray diffraction (XRD), Fourier transform infrared spectra (FTIR), Thermogravimetry-differential scanning calorimetry (TG-DSC), scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The experimental results showed that glucose greatly lower the phase transformation temperature of alpha-alumina by impelling the gamma-alumina transformed to alpha-alumina directly, and the seed could improve the phase transformation rate of alpha-alumina, the polyvinylpyrrolidone have an effect on preventing excessive grain growth and agglomeration of alpha-alumina powder. Comparatively well dispersed alpha-alumina powder with particle size less than 50 nm can be synthesized through this method after calcinations at 1000 °C for 2 h.

  9. Selective recovery of silver from waste low-temperature co-fired ceramic and valorization through silver nanoparticle synthesis.

    Science.gov (United States)

    Swain, Basudev; Shin, Dongyoon; Joo, So Yeong; Ahn, Nak Kyoon; Lee, Chan Gi; Yoon, Jin-Ho

    2017-11-01

    Considering the value of silver metal and silver nanoparticles, the waste generated during manufacturing of low temperature co-fired ceramic (LTCC) were recycled through the simple yet cost effective process by chemical-metallurgy. Followed by leaching optimization, silver was selectively recovered through precipitation. The precipitated silver chloride was valorized though silver nanoparticle synthesis by a simple one-pot greener synthesis route. Through leaching-precipitation optimization, quantitative selective recovery of silver chloride was achieved, followed by homogeneous pure silver nanoparticle about 100nm size were synthesized. The reported recycling process is a simple process, versatile, easy to implement, requires minimum facilities and no specialty chemicals, through which semiconductor manufacturing industry can treat the waste generated during manufacturing of LTCC and reutilize the valorized silver nanoparticles in manufacturing in a close loop process. Our reported process can address issues like; (i) waste disposal, as well as value-added silver recovery, (ii) brings back the material to production stream and address the circular economy, and (iii) can be part of lower the futuristic carbon economy and cradle-to-cradle technology management, simultaneously. Copyright © 2017 Elsevier Ltd. All rights reserved.

  10. Low-temperature solid-state synthesis and optical properties of ZnO/CdS nanocomposites

    International Nuclear Information System (INIS)

    Liu, Jinsong; Zhu, Kongjun; Sheng, Beibei; Li, Ziquan; Tai, Guoan; Qiu, Jinhao; Wang, Jing; Chen, Jiankang; You, Yuncheng; Gu, Qilin; Liu, Pengcheng

    2015-01-01

    Highlights: • Using a low-temperature solid-state method, ZnO/CdS nanocomposites were obtained • Grain growth kinetics of cubic CdS and hexagonal ZnO phase was described. • Sufficient grinding and heating treatment was a key for formation of composites. • Optical properties could be easily manipulated by reaction temperature and time. - Abstract: A simple low-temperature solid-state reaction in the presence of the surfactant PEG400 was developed to obtain ZnO/CdS nanocomposites. The effects of synthesis temperature and reaction time on crystal structure and optical properties of the nanocomposites were investigated by several technologies. X-ray diffraction (XRD) and high resolution transmission electron microscope (HRTEM) characterizations showed that the products consisted of the nanoparticles, and the grain growth kinetics of the cubic CdS and the hexagonal ZnO phase in the nanocomposites was described. The mechanism analysis suggested that sufficient grinding and heating treatment was a key to form the ZnO/CdS nanocomposites, and the surfactant PEG400 was proved not to involve the reaction and prevent the nanoparticles from aggregating to larger in whole grinding and heat-treatment process. Ultraviolet–visible (UV–vis) spectra revealed that the band gaps of the nanocomposites could be tuned by the reaction temperature and reaction time. Photoluminescence (PL) spectra showed that the changing position and the intensity of the emission peaks resulted from the rate of electron transfer and recombination probability under the different conditions

  11. Synthesis of dimethyl carbonate by oxidative carbonylation of methanol

    Energy Technology Data Exchange (ETDEWEB)

    Lee, B.G.; Han, M.S.; Kim, H.S.; Ahn, B.S.; Park, K.Y.

    1999-07-01

    Dimethyl carbonate (DMC) synthesis reaction by oxidative carbonylation of methanol has been studied using vapor phase flow reaction system in the presence of Cu-based catalysts. A series of Cu-based catalysts were prepared by the conventional impregnation method using activated carbon (AC) as support. The effect of various promoters and reaction conditions on the catalytic reactivities was intensively evaluated in terms of methanol conversion and DMC selectivity. The morphological change of catalysts during the reaction was also compared by X-ray diffraction and SEM analysis. Regardless of catalyst compositions, the optimal reaction temperature for oxidative carbonylation of methanol was found to be around 120--130 C. The reaction rate was too slow below 100 C, while too many by-products were produced above 150 C. Among the various catalysts employed, CuCl{sub 2}/NaOH/AC catalyst with the mole ratio of OH/Cu = 0.5--1.0 has shown the best catalytic performance, which appears to have a strong relationship with the formation of intermediate species, Cu{sub 2}(OH){sub 3}Cl.

  12. Transient behavior of Cu/ZnO-based methanol synthesis catalysts

    DEFF Research Database (Denmark)

    Vesborg, Peter Christian Kjærgaard; Chorkendorff, Ib; Knudsen, Ida

    2009-01-01

    Time-resolved measurements of the methanol synthesis reaction over a Cu/ZnO-based catalyst reveal a transient methanol production that depends on the pretreatment gas. Specifically, the methanol production initially peaks after a pretreatment with an intermediate mixture of H2 and CO (20–80% H2...

  13. A novel process for methanol synthesis. Final report

    Energy Technology Data Exchange (ETDEWEB)

    Tierney, J.W.; Wender, I.

    1994-01-25

    The use of methanol (MeOH) as a fuel additive and in MTBE production has renewed interest in the search for improved MeOH processes. Commercial processes are characterized by high pressures and temperatures with low per pass conversion (10--12%). Efforts are underway to find improved MeOH synthesis processes. A slurry phase ``concurrent`` synthesis of MeOH/methyl formate (MeF) which operates under relatively mild conditions (100{degrees}C lower than present commercial processes) was the subject of investigation in this work. Evidence for a reaction scheme involving the carbonylation of MeOH to MeF followed by the hydrogenolysis of MeF to two molecules of MeOH -- the net result being the reaction of H{sub 2} with CO to give MeOH via MeF, is presented. Up to 90% per pass conversion and 98% selectivity to methanol at rates comparable to commercial processes have been obtained in spite of the presence of as much as 10,000 ppM CO{sub 2} and 3000 ppM H{sub 2}O in the gas and liquid respectively. The effect of process parameters such as temperature, pressure, H{sub 2}/CO ratio in the reactor, flow rate and catalyst loading were also investigated. The use of temperatures above 170{degrees}C at a pressure of 50 atm results in MeF being the limiting reactant. Small amounts of CH{sub 4} are also formed. Significant MeOH synthesis rates at a pressure in the range of 40--50 atm makes possible the elimination of an upstream shift reactor and the use of an air-blown syngas generator. The nature of the catalysts was studied and correlated with the behavior of the various species in the concurrent synthesis.

  14. Low temperature synthesis, characterization and tunable optical properties of Eu3+, Tb3+ doped CaMoO4 nanoparticles

    International Nuclear Information System (INIS)

    Sharma, K. Gayatri; Singh, Th. Prasanta; Singh, N. Rajmuhon

    2014-01-01

    Highlights: • Red and green nanophosphors of CaMoO 4 :Eu 3+ and Tb 3+ were synthesized via an ethylene glycol route at very low temperature. • The prepared nanoparticles have tetragonal structure. • The luminescence properties of the nanoparticles are also studied extensively. • CIE chromaticity coordinates of the phosphors are also studied. • The blue-green emission of host could be easily tuned to red or green by varying the dopant ion used in the host. - Abstract: CaMoO 4 doped with Eu 3+ and Tb 3+ nanoparticles are obtained using ethylene glycol as the solvent. The synthesis has been carried out at 130 °C temperature. The XRD patterns reveal that all the doped samples are well assigned to the scheelite structure of the CaMoO 4 phase. Upon excitation by ultraviolet radiation, the CaMoO 4 :Eu 3+ , Tb 3+ phosphors show the characteristic emission lines of Eu 3+ and Tb 3+ . For Eu 3+ doped samples, red emission dominates over other transitions and for Tb 3+ doped, green emission is the predominant one. The blue-green emission of the host could be easily tuned to red and green by doping with activator ions. The emission intensity is also dependent on the concentration of the dopant ions. The prepared nanoparticles could find applications in LEDs and other optical devices

  15. Low-temperature synthesis of hexagonal transition metal ion doped ZnS nanoparticles by a simple colloidal method

    International Nuclear Information System (INIS)

    Wang, Liping; Huang, Shungang; Sun, Yujie

    2013-01-01

    A general route to synthesize transition metal ions doped ZnS nanoparticles with hexagonal phase by means of a conventional reverse micelle at a low temperature is developed. The synthesis involves N,N-dimethylformamide, Zn(AC) 2 solution, thiourea, ammonia, mercaptoacetic acid, as oil phase, water phase, sulfide source, pH regulator, and surfactant, respectively. Thiourea, ammonia and mercaptoacetic acid are demonstrated crucial factors, whose effects have been studied in detail. In addition, the FT-IR spectra suggest that mercaptoacetic acid may form complex chelates with Zn 2+ in the preparation. In the case of Cu 2+ as a doped ion, hexagonal ZnS:Cu 2+ nanoparticles were synthesized at 95 °C for the first time. The X-ray diffraction (XRD) and transmission electron microscope (TEM) measurements show that the ZnS:Cu 2+ nanoparticles are polycrystalline and possess uniform particle size. The possible formation mechanism of the hexagonal doped ZnS is discussed.

  16. Low temperature molten salt synthesis of Y(sub2)Sn(sub2)O(sub7) anode material for lithium ion batteries

    CSIR Research Space (South Africa)

    Nithyadharseni, P

    2015-10-01

    Full Text Available Acta 182 (2015) 1060–1069 Low temperature molten salt synthesis of Y2Sn2O7 anode material for lithium ion batteries P. Nithyadharsenia,b, M.V. Reddya,c,*, Kenneth I. Ozoemenab,d, R. Geetha Balakrishnae, B.V.R. Chowdaria a Advanced Batteries...

  17. Low temperature activation of methane over a zinc-exchanged heteropolyacid as an entry to its selective oxidation to methanol and acetic acid

    KAUST Repository

    Patil, Umesh; Saih, Youssef; Abou-Hamad, Edy; Hamieh, Ali Imad Ali; Pelletier, Jeremie; Basset, Jean-Marie

    2014-01-01

    A Zn-exchanged heteropolyacid supported onto silica (Zn-HPW/SiO2) activates methane at 25 °C into Zn-methyl. At higher temperatures and with CH4/O2 or CH4/CO2, it gives methanol and acetic acid respectively. This journal is

  18. Synthesis and characterisation of novel low temperature ceramic and its implementation as substrate in dual segment CDRA

    Science.gov (United States)

    Kumari, Preeti; Tripathi, Pankaj; Sahu, Bhagirath; Singh, S. P.; Parkash, Om; Kumar, Devendra

    2018-02-01

    Li2O-(2-3x)MgO-(x)Al2O3-P2O5 (LMAP) (x = 0.00-0.08) ceramic system was prepared through solid state synthesis route at different sintering temperatures (800-925 °C). A small addition of Al2O3 (x = 0.02) in LMAP ceramics lowers the sintering temperature by more than 100 °C with good relative density of 94.13%. The sintered samples were characterized in terms of density, apparent porosity, water absorption, crystal structure, micro-structure and microwave dielectric properties. Silver compatibility test is also performed for its use as electrode material in low temperature co-fired ceramic (LTCC) application. To check the performance of the prepared LTCC as substrate, a microstrip-fed aperture-coupled dual segment cylindrical dielectric resonator antenna (DS-CDRA) is designed using LMAP (x = 0.02) ceramic as substrate material and Barium Strontium Titanate with 10 wt% of PbO-BaO-B2O3-SiO2 glass (BSTG) and Teflon as the components of resonating material. The simulation study of the DS-CDRA is performed using the Ansys High Frequency Structure Simulator (HFSS) software. A conductive coating of silver is used on the substrate. The simulated and measured -10 dB reflection coefficient bandwidths of 910 MHz (9.07-9.98 GHz at resonant frequency of 9.49 GHz) and 1080 MHz (8.68-9.76 GHz at resonant frequency of 9.36 GHz), respectively are achieved. The measured results of the fabricated antenna are found in good agreement with the simulation results. The prepared material can find potential applications in radar and radio navigation as well as radio astronomy and military satellite communication.

  19. Low-temperature synthesis of Zn{sub 2}SiO{sub 4}:Mn green photoluminescence phosphor

    Energy Technology Data Exchange (ETDEWEB)

    Sivakumar, V. [Saveetha Engineering College, Thandalam, Chennai 602105 (India); Lakshmanan, Arunachalam, E-mail: arunachalamlakshmanan@yahoo.com [Saveetha Engineering College, Thandalam, Chennai 602105 (India); Kalpana, S.; Sangeetha Rani, R.; Satheesh Kumar, R. [Saveetha Engineering College, Thandalam, Chennai 602105 (India); Jose, M.T. [Radiological Safety Division, Indira Gandhi Centre for Atomic Research, Kalpakkam 603102 (India)

    2012-08-15

    Zn{sub 2}SiO{sub 4}:Mn green phosphor having comparable photoluminescence (PL) efficiency with commercial phosphor has been synthesized at 1000 Degree-Sign C using solid state reactions involving ZnO, silicic acid and manganese acetate. The water of crystallization attached to SiO{sub 2} in silicic acid whose dissociation at 1000 Degree-Sign C seem to promote the sintering efficiency of Zn{sub 2}SiO{sub 4}:Mn. Incremental ZnO addition and re-firing at 1000 Degree-Sign C promote the diffusion rate of ZnO and SiO{sub 2}. The formation of a single crystalline phase of willemite structure in the samples was confirmed by powder XRD measurements. The phosphor exhibit an intense excitation band centered around 275 nm and a relatively weak excitation centered around 380 nm while the broad band green emission peaks at 524 nm. Other parameters studied include PL spectra, grain morphology, ZnO/SiO{sub 2} molar ratio, Mn concentration, co-dopant/flux and the effect of chemical forms of Mn dopant as well as silica on the PL efficiency. - Highlights: Black-Right-Pointing-Pointer Synthesis of Zn{sub 2}SiO{sub 4}:Mn by solid state sintering at a low temperature of 1000 Degree-Sign C in air. Black-Right-Pointing-Pointer Dissociation of water of crystallization in silicic acid promote sintering efficiency. Black-Right-Pointing-Pointer Photoluminescence efficiency comparable with that of the commercial phosphor. Black-Right-Pointing-Pointer Enhancement in luminescence with MgCO{sub 3} co-doping and refiring as well as ZnO addition. Black-Right-Pointing-Pointer XRD confirm single phase willemite structure (rhombohedral) of Zn{sub 2}SiO{sub 4}:Mn.

  20. Synthesis of dimethyl carbonate from urea and methanol

    Energy Technology Data Exchange (ETDEWEB)

    Polyakov, M.; Kalevaru, V.N.; Martin, A. [Rostock Univ. (Germany). Leibniz Institute for Catalysis; Mueller, K.; Arlt, W. [Erlangen-Nuernberg Univ. (Germany); Strautmann, J.; Kruse, D. [Evonik Industries AG, Marl (Germany). Creavis Technologies and Innovation

    2012-07-01

    Alcoholation of urea with methanol to produce dimethyl carbonate (DMC) is an interesting approach from both the ecological and economical points of view because the urea synthesis usually occurs by the direct use of carbon dioxide. Literature survey reveals that metal oxide catalysts for instance MgO, ZnO, etc. or polyphosphoric acids are mostly used as catalysts for this reaction. In this contribution, we describe the application of ZnO, MgO, CaO, TiO{sub 2}, ZrO{sub 2} or Al{sub 2}O{sub 3} catalysts for the above mentioned reaction. The catalytic activity of different metal oxides towards DMC synthesis was checked and additionally a comparison of achieved conversions with that of predictions made by thermodynamic calculations was also carried out. The achieved conversions are in good agreement with those of calculated ones. The test results reveal that the reaction pressure and temperature have a strong influence on the formation of DMC. Higher reaction pressure improved the yield of DMC. Among different catalysts investigated, ZnO displayed the best performance. The conversion of urea in most cases is close to 100 % and methyl carbamate MC is the major product of the reaction. A part of MC is subsequently converted to DMC, which however depends upon the reaction conditions applied and nature of catalyst used. From the best case, a DMC yield of ca. 8 % could be successfully achieved over ZnO catalyst. (orig.)

  1. Low temperature synthesis of seed mediated CuO bundle of nanowires, their structural characterisation and cholesterol detection

    Energy Technology Data Exchange (ETDEWEB)

    Ibupoto, Z.H., E-mail: zafar.hussin.ibupoto@liu.se [Department of Science and Technology, Linköping University, Campus Norrköping, SE-60174 Norrköping (Sweden); Khun, K. [Department of Science and Technology, Linköping University, Campus Norrköping, SE-60174 Norrköping (Sweden); Liu, X. [Department of Physics, Chemistry, and Biology (IFM), Linköping University, 58183 Linköping Sweden (Sweden); Willander, M. [Department of Science and Technology, Linköping University, Campus Norrköping, SE-60174 Norrköping (Sweden)

    2013-10-15

    In this study, we have successfully synthesised CuO bundle of nanowires using simple, cheap and low temperature hydrothermal growth method. The growth parameters such as precursor concentration and time for duration of growth were optimised. The field emission scanning electron microscopy (FESEM) has demonstrated that the CuO bundles of nanowires are highly dense, uniform and perpendicularly oriented to the substrate. The high resolution transmission electron microscopy (HRTEM) has demonstrated that the CuO nanostructures consist of bundle of nanowires and their growth pattern is along the [010] direction. The X-ray diffraction (XRD) technique described that CuO bundle of nanowires possess the monoclinic crystal phase. The surface and chemical composition analyses were carried out with X-ray photoelectron spectroscopy (XPS) technique and the obtained results suggested the pure crystal state of CuO nanostructures. In addition, the CuO nanowires were used for the cholesterol sensing application by immobilising the cholesterol oxidase through electrostatic attraction. The infrared reflection absorption spectroscopy study has also revealed that CuO nanostructures are consisting of only Cu-O bonding and has also shown the possible interaction of cholesterol oxidase with the sharp edge surface of CuO bundle of nanowires. The proposed cholesterol sensor has demonstrated the wide range of detection of cholesterol with good sensitivity of 33.88 ± 0.96 mV/decade. Moreover, the CuO bundle of nanowires based sensor electrode has revealed good repeatability, reproducibility, stability, selectivity and a fast response time of less than 10 s. The cholesterol sensor based on the immobilised cholesterol oxidase has good potential applicability for the determination of cholesterol from the human serum and other biological samples. - Highlights: • This study describes the synthesis of bundle of CuO nanowires by hydrothermal method. • CuO nanostructures exhibit good alignment and

  2. Low temperature synthesis of seed mediated CuO bundle of nanowires, their structural characterisation and cholesterol detection

    International Nuclear Information System (INIS)

    Ibupoto, Z.H.; Khun, K.; Liu, X.; Willander, M.

    2013-01-01

    In this study, we have successfully synthesised CuO bundle of nanowires using simple, cheap and low temperature hydrothermal growth method. The growth parameters such as precursor concentration and time for duration of growth were optimised. The field emission scanning electron microscopy (FESEM) has demonstrated that the CuO bundles of nanowires are highly dense, uniform and perpendicularly oriented to the substrate. The high resolution transmission electron microscopy (HRTEM) has demonstrated that the CuO nanostructures consist of bundle of nanowires and their growth pattern is along the [010] direction. The X-ray diffraction (XRD) technique described that CuO bundle of nanowires possess the monoclinic crystal phase. The surface and chemical composition analyses were carried out with X-ray photoelectron spectroscopy (XPS) technique and the obtained results suggested the pure crystal state of CuO nanostructures. In addition, the CuO nanowires were used for the cholesterol sensing application by immobilising the cholesterol oxidase through electrostatic attraction. The infrared reflection absorption spectroscopy study has also revealed that CuO nanostructures are consisting of only Cu-O bonding and has also shown the possible interaction of cholesterol oxidase with the sharp edge surface of CuO bundle of nanowires. The proposed cholesterol sensor has demonstrated the wide range of detection of cholesterol with good sensitivity of 33.88 ± 0.96 mV/decade. Moreover, the CuO bundle of nanowires based sensor electrode has revealed good repeatability, reproducibility, stability, selectivity and a fast response time of less than 10 s. The cholesterol sensor based on the immobilised cholesterol oxidase has good potential applicability for the determination of cholesterol from the human serum and other biological samples. - Highlights: • This study describes the synthesis of bundle of CuO nanowires by hydrothermal method. • CuO nanostructures exhibit good alignment and

  3. Low temperature synthesis of polyaniline-crystalline TiO2-halloysite composite nanotubes with enhanced visible light photocatalytic activity.

    Science.gov (United States)

    Li, Cuiping; Wang, Jie; Guo, Hong; Ding, Shujiang

    2015-11-15

    A series of one-dimensional polyaniline-crystalline TiO2-halloysite composite nanotubes with different mass ratio of polyaniline to TiO2 are facilely prepared by employing the low-temperature synthesis of crystalline TiO2 on halloysite nanotubes. The halloysite nanotubes can adsorb TiO2/polyaniline precursors and induce TiO2 nanocrystals/polyaniline to grow on the support in situ simultaneously. By simply adjusting the acidity of reaction system, PANI-crystalline TiO2-HA composite nanotubes composed of anatase, a mixed phase TiO2 and different PANI redox state are obtained. The XRD and UV-vis results show that the surface polyaniline sensitization has no effect on the crystalline structure of halloysite and TiO2 and the light response of TiO2 is extended to visible-light regions. Photocatalysis test results reveal the photocatalytic activity will be affected by the pH value and the volume ratio of ANI to TTIP. The highest photocatalytic activity is achieved with the composite photocatalysts prepared at pH 0.5 and 1% volume ratio of ANI and TTIP owing to the sensitizing effect of polyaniline and the charge transfer from the photoexcited PANI sensitizer to TiO2. Moreover, the PANI-TiO2-HA composite nanotubes synthesized by one-step at pH 0.5 with 1% volume ratio of ANI to TTIP exhibit higher visible light photocatalytic activity than those synthesized by the two-step. Heterogeneous PANI-TiO2-HA composite nanotubes prepared at pH 0.5 exhibit a higher degradation activity than that prepared at pH 1.5. The redoped experiment proves that the PANI redox state plays the main contribution to the enhanced visible light catalytic degradation efficiency of PANI-TiO2-HA prepared at pH 0.5. Furthermore, the heterogeneous PANI-crystalline TiO2-HA nanotubes have good photocatalytic stability and can be reused four times with only gradual loss of activity under visible light irradiation. Copyright © 2015 Elsevier Inc. All rights reserved.

  4. Thermochemistry and micro-kinetic analysis of methanol synthesis on ZnO (0001)

    DEFF Research Database (Denmark)

    Medford, Andrew James; Sehested, Jens; Rossmeisl, Jan

    2014-01-01

    In this work, we examine the thermochemistry of methanol synthesis intermediates using density functional theory (DFT) and analyze the methanol synthesis reaction network using a steady-state micro-kinetic model. The energetics for methanol synthesis over Zn-terminated ZnO (0001) are obtained from...... DFT calculations using the RPBE and BEEF-vdW functionals. The energies obtained from the two functionals are compared and it is determined that the BEEF-vdW functional is more appropriate for the reaction. The BEEF-vdW energetics are used to construct surface phase diagrams as a function of CO, H2O......, and H2 chemical potentials. The computed binding energies along with activation barriers from literature are used as inputs for a mean-field micro-kinetic model for methanol synthesis including the CO and CO2 hydrogenation routes and the water–gas shift reaction. The kinetic model is used to investigate...

  5. Direct synthesis of dimethyl carbonate from CO2 and methanol over ...

    Indian Academy of Sciences (India)

    The direct synthesis of dimethyl carbonate (DMC) from carbon dioxide (CO2) and methanol is ... Zirconia and ceria-based catalysts were most effective ... construction of a validation plant for dialkyl carbonates .... (mmol of MeOH consumed/2).

  6. TiO2 and Al2O3 promoted Pt/C nanocomposites as low temperature fuel cell catalysts for electro oxidation of methanol in acidic media

    International Nuclear Information System (INIS)

    Naeem, Rabia; Ahmed, Riaz; Ansari, Muhammad Shahid

    2014-01-01

    Carbon corrosion and platinum dissolution are the two major catalyst layer degradation problems in polymer electrolyte membrane fuel cells (PEMFC). Ceramic addition can reduce the corrosion of carbon and increase the stability of catalysts. Pt/TiO 2 , Pt/TiO 2 -C, Pt/Al 2 O 3 and Pt/Al 2 O 3 -C catalysts were synthesized and characterized. Electrochemical surface area of Pt/TiO 2 -C and Pt/Al 2 O 3 -C nanocomposite catalysts was much higher than the Pt/TiO 2 and Pt/Al 2 O 3 catalysts. Peak current, specific activity and mass activity of the catalysts was also determined by cyclic voltammetry and were much higher for the carbon nanocomposites. Exchange current densities were determined from Tafel plots. Heterogeneous rates of reaction of electro oxidation of methanol were determined for all the catalysts and were substantially higher for titania catalysts as compared to alumina added catalysts. Mass activity of Pt/TiO 2 -C was much higher than mass activity of Pt/Al 2 O 3 -C. Stability studies showed that addition of ceramics have increased the catalytic activity and durability of the catalysts considerably

  7. Study on methanol synthesis from coal-based syngas

    Energy Technology Data Exchange (ETDEWEB)

    Hong-fang Ma; Wei-yong Ying; Ding-ye Fang [East China University of Science and Technology, Shanghai (China). State Key Laboratory of Chemical Engineering

    2009-03-15

    The intrinsic kinetic models of the Langmuir-Hinshelwood type were investigated in terms of the reaction rates of CO hydrogenation and CO{sub 2} hydrogenation in the form of reactant fugacity. The parameters were estimated by the Universal Global Optimization using the Marquardt method. Residual error distribution and statistic tests show that the intrinsic kinetic models are reliable and acceptable. The mathematic model of a combined converter formed by gas-cooled and water-cooled reactor was developed and the gas-cooled reactor and the water-cooled reactor were characterized with one-dimensional mathematic model. The distributions of temperature and concentration in the catalytic bed of the gas-cooled reactor and the water-cooled reactor in a combined converter with a yield of 1.2 Mt/a were simulated. The parallel cross linking pore model was used to describe the transfer process of multi-component diffusion system in the catalyst. The calculated value computed by the internal diffusion efficiency factor calculation model established for methanol synthesis catalyst fit the experimental value very well. 11 refs., 3 figs., 3 tabs.

  8. Facile, low temperature synthesis of SnO_2/reduced graphene oxide nanocomposite as anode material for lithium-ion batteries

    International Nuclear Information System (INIS)

    Hou, Chau-Chung; Brahma, Sanjaya; Weng, Shao-Chieh; Chang, Chia-Chin; Huang, Jow-Lay

    2017-01-01

    Highlights: • Facile, one-pot, low temperature synthesis of SnO_2-RGO composite. • In-situ reduction of graphene oxide and growth of SnO_2 nanoparticle. • Concentration of reductant during synthesis affects the properties significantly. • SnO_2-RGO composite shows good rate capability and stable capacitance. • Synthesis method is energy efficient and scalable for other metal oxides. - Abstract: We demonstrate a facile, single step, low temperature and energy efficient strategy for the synthesis of SnO_2-reduced graphene oxide (RGO) nanocomposite where the crystallization of SnO_2 nanoparticles and the reduction of graphene oxide takes place simultaneously by an in situ chemical reduction process. The electrochemical property of the SnO_2-RGO composite prepared by using low concentrations of reducing agent shows better Li storage performance, good rate capability (378 mAh g"−"1 at 3200 mA g"−"1) and stable capacitance (522 mAh g"−"1 after 50 cycles). Increasing the reductant concentration lead to crystallization of high concentration of SnO_2 nanoparticle aggregation and degrade the Li ion storage property.

  9. Facile, low temperature synthesis of SnO{sub 2}/reduced graphene oxide nanocomposite as anode material for lithium-ion batteries

    Energy Technology Data Exchange (ETDEWEB)

    Hou, Chau-Chung; Brahma, Sanjaya; Weng, Shao-Chieh [Department of Materials Science and Engineering, National Cheng Kung University, Tainan 70001, Taiwan, ROC (China); Chang, Chia-Chin [Department of Greenergy, National University of Tainan, Tainan 70005, Taiwan, ROC (China); Huang, Jow-Lay, E-mail: jlh888@mail.ncku.edu.tw [Department of Materials Science and Engineering, National Cheng Kung University, Tainan 70001, Taiwan, ROC (China); Department of Chemical and Materials Engineering, National University of Kaohsiung, Kaohsiung 81148, Taiwan, ROC (China); Center for Micro/Nano Science and Technology, National Cheng Kung University, Tainan 70101, Taiwan, ROC (China)

    2017-08-15

    Highlights: • Facile, one-pot, low temperature synthesis of SnO{sub 2}-RGO composite. • In-situ reduction of graphene oxide and growth of SnO{sub 2} nanoparticle. • Concentration of reductant during synthesis affects the properties significantly. • SnO{sub 2}-RGO composite shows good rate capability and stable capacitance. • Synthesis method is energy efficient and scalable for other metal oxides. - Abstract: We demonstrate a facile, single step, low temperature and energy efficient strategy for the synthesis of SnO{sub 2}-reduced graphene oxide (RGO) nanocomposite where the crystallization of SnO{sub 2} nanoparticles and the reduction of graphene oxide takes place simultaneously by an in situ chemical reduction process. The electrochemical property of the SnO{sub 2}-RGO composite prepared by using low concentrations of reducing agent shows better Li storage performance, good rate capability (378 mAh g{sup −1} at 3200 mA g{sup −1}) and stable capacitance (522 mAh g{sup −1} after 50 cycles). Increasing the reductant concentration lead to crystallization of high concentration of SnO{sub 2} nanoparticle aggregation and degrade the Li ion storage property.

  10. Phase equilibria at low temperature for light hydrocarbons-methanol-water-acid gases mixtures: measurements and modelling; Equilibres de phases a basse temperature de systemes complexes CO{sub 2} - hydrocarbures legers - methanol - eau: mesures et modelisation

    Energy Technology Data Exchange (ETDEWEB)

    Ruffine, L.

    2005-10-15

    The need to develop and improve natural gas treatment processes is real. The petroleum industry usually uses separation processes which require phase equilibrium phenomena. Yet, the complexity of the phase equilibria involved results in a lack of data, which in turn limits the development of thermodynamic models. The first part of this work is devoted to experimental investigations for systems containing light hydrocarbons, methanol, water and acid gases. We present a new apparatus that was developed to measure vapor-liquid and vapor-liquid-liquid equilibria. It allowed us to obtain new phase composition data for the methanol-ethane binary system and different mixtures, and also to determine a part of the three phases equilibrium envelope of the same systems. In the second part of this work, we have developed a thermodynamic model based on the CPA equation of state. This choice may be justified by the presence of associating components like methanol, hydrogen sulfide and water in the systems. Such model is necessary for the design of gas treatment plants. Our model provides good results for phase equilibrium calculations for binaries systems without binary interaction parameter in many cases, and describes correctly the vapour-liquid and vapor-liquid-liquid equilibria for complex mixtures. (author)

  11. Utilisation of reactor heat in methanol synthesis to reduce compressor duty : application of power cycle principles and simulation tools

    NARCIS (Netherlands)

    Greeff, I.L.; Visser, J.A.; Ptasinski, K.J.; Janssen, F.J.J.G.

    2002-01-01

    The chemical conversion in a methanol reactor is restricted by equilibrium, therefore the synthesis loop is operated at high pressure and unconverted gas is recycled. Such a synthesis loop consumes large amounts of compression work. In this paper a new flow sheet for methanol synthesis is presented.

  12. Quantifying the promotion of Cu catalysts by ZnO for methanol synthesis

    DEFF Research Database (Denmark)

    Kuld, Sebastian; Thorhauge, Max; Falsig, Hanne

    2016-01-01

    Promoter elements enhance the activity and selectivity of heterogeneous catalysts. Here, we show how methanol synthesis from synthesis gas over copper (Cu) nanoparticles is boosted by zinc oxide (ZnO) nanoparticles. By combining surface area titration, electron microscopy, activity measurement, d...

  13. Low temperature and surfactant-free synthesis of Pd2Sn intermetallic nanoparticles for ethanol electro-oxidation

    International Nuclear Information System (INIS)

    Wang, Congmin; Wu, Yurong; Wang, Xin; Zou, Liangliang; Zou, Zhiqing; Yang, Hui

    2016-01-01

    Many intermetallic compounds have a predictable structure, interesting electronic effects, and useful catalytic properties. In this work, a low temperature, surfactant-free, and one-pot method is used to synthesize carbon supported Pd 2 Sn intermetallic nanoparticles. The superlattice of the product was then characterized using X-ray diffraction and transmission electron microscopy. These synthesized intermetallic nanoparticles were found to exhibit a higher activity and stability for electrocatalysis of the ethanol oxidation reaction in an alkaline media than has been achieved using a traditional Pd/C catalyst, which could be attributed to the structural and compositional stabilities of ordered Pd 2 Sn intermetallic nanoparticles.

  14. Low-temperature synthesis of CuFeO{sub 2} (delafossite) at 70 °C: A new process solely by precipitation and ageing

    Energy Technology Data Exchange (ETDEWEB)

    John, Melanie, E-mail: melanie.john@min.uni-muenchen.de [Section Mineralogy, Petrology & Geochemistry, Department of Earth and Environmental Sciences, Ludwig-Maximilians-Universität München, Theresienstr. 41, 80333 Munich (Germany); Heuss-Aßbichler, Soraya [Section Mineralogy, Petrology & Geochemistry, Department of Earth and Environmental Sciences, Ludwig-Maximilians-Universität München, Theresienstr. 41, 80333 Munich (Germany); Park, So-Hyun [Section Crystallography, Department of Earth and Environmental Sciences, Ludwig-Maximilians-Universität München, Theresienstr. 41, 80333 Munich (Germany); Ullrich, Aladin [Experimental Physics II, University of Augsburg, Universitätsstr. 1, 86159 Augsburg (Germany); Benka, Georg [Physics Department, Technical University Munich, James-Franck-Straße 1, 85748 Garching (Germany); Petersen, Nikolai [Section Geophysics, Department of Earth and Environmental Sciences, Ludwig-Maximilians-Universität München, Theresienstr. 41, 80333 Munich (Germany); Rettenwander, Daniel [Department of Materials Research & Physics, University of Salzburg, Hellbrunnerstrasse 34, 5020 Salzburg (Austria); Horn, Siegfried R. [Experimental Physics II, University of Augsburg, Universitätsstr. 1, 86159 Augsburg (Germany)

    2016-01-15

    This study presents a new low temperature synthesis method to obtain pure delafossite (Cu{sup 1+}Fe{sup 3+}O{sub 2}) at a temperature of 70 °C within 24 h. For the first time delafossite is synthesized solely by precipitation and subsequent ageing process and without usage of any additives controlling the oxidation state of copper. The synthesized material, called LT-delafossite, consists of pure Cu{sup 1+}Fe{sup 3+}O{sub 2} exclusive of any side products. Rietveld analysis confirms the presence of both 3R (space group (SG): R-3m) and 2H (SG: P6{sub 3}/mmc) polytypes in LT-delafossite. Electron microscopy images show nanometer-sized hexagonal plates with a diameter <500 nm and a thickness of <30 nm. Measurements of the magnetic susceptibility from 2 K to 350 K in zero-field show one peak ∼18.5 K, which is attributed to an AFM phase transition. Zero-field-cooled magnetization data between −14 T and +14 T at 2 K revealed an s-shape form around the origin having no remanent magnetization. - Highlights: • New process: low temperature synthesis of pure CuFeO{sub 2} nanoparticles. • Synthesis at 70 °C within 24 h solely by precipitation and ageing. • Nanoparticle characterization by XRD, FTIR, SEM, ICP–OES, TEM and Mößbauer. • Special magnetic properties of nano-sized CuFeO{sub 2} synthesized at low temperatures.

  15. Low temperature molten salt synthesis of Y2Sn2O7 anode material for lithium ion batteries

    International Nuclear Information System (INIS)

    Nithyadharseni, P.; Reddy, M.V.; Ozoemena, Kenneth I.; Balakrishna, R. Geetha; Chowdari, B.V.R.

    2015-01-01

    Highlights: • For the first time Y 2 Sn 2 O 7 compound was prepared at very low temperature by molten salt method. • We studied the effect of reheating on electrochemical properties. • All the compounds showed particle size of below 500 nm. • The all compounds showed a stable and good capacity retention during cycling. - Abstract: For the first time, yttrium tin oxide (Y 2 Sn 2 O 7 ) compound is prepared at low temperature (400 °C) with cubic pyrochlore structure via molten salt method using KOH as a flux for their electrochemical applications. The final product is reheated at three different temperatures of 600, 800 and 1000 °C for 6 h in air, are physically and chemically characterized by various techniques such as X-ray diffraction (XRD), scanning electron microscope (SEM) and electrochemical studies of galvanostatic cycling (GC), cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS). Galvanostatic cycling of Y 2 Sn 2 O 7 compounds are carried out with three different current densities of 60, 100 and 250 mA g −1 and the potential range of 0.005–1.0 V vs. Li. The EIS is carried out to study the electrode kinetics during discharge and charge at various voltages and corresponding variation of resistance and capacitance values are discussed.

  16. Low temperature synthesis of Ba1–xSrxSnO3 (x = 0–1) from molten ...

    Indian Academy of Sciences (India)

    Administrator

    first time by molten salt synthesis (MSS) method using KOH as the flux at lower temperature (400°C) compared to other ... chemical methods have been adopted by many research- ers. .... financial support and Technology Business Incubator,.

  17. One-pot synthesis of graphene supported platinum–cobalt nanoparticles as electrocatalysts for methanol oxidation

    International Nuclear Information System (INIS)

    Kepenienė, V.; Tamašauskaitė-Tamašiūnaitė, L.; Jablonskienė, J.; Semaško, M.; Vaičiūnienė, J.; Vaitkus, R.; Norkus, E.

    2016-01-01

    In the present study the graphene supported platinum–cobalt nanoparticles were prepared via microwave synthesis. The composition of prepared catalysts was examined by Inductively Coupled Plasma Optical Emission Spectroscopy. The shape and size of catalyst particles were determined by Transmission Electron Microscopy. The electrocatalytic activity of the graphene supported platinum–cobalt nanoparticles was investigated towards the electro-oxidation of methanol in an alkaline medium. It has been found that the graphene supported platinum–cobalt nanoparticles having the Pt:Co molar ratio 1:7 show the highest activity towards the electro-oxidation of methanol among the catalysts with the Pt:Co molar ratios equal to 1:1 and 1:44, graphene supported bare Co and Pt/C catalysts. - Highlights: • Preparation of graphene supported Pt-Co nanoparticles by microwave synthesis. • Electrocatalysts for oxidation of methanol. • Higher activity of PtCo/graphene towards methanol oxidation.

  18. One-pot synthesis of graphene supported platinum–cobalt nanoparticles as electrocatalysts for methanol oxidation

    Energy Technology Data Exchange (ETDEWEB)

    Kepenienė, V., E-mail: virginalisk@gmail.com [Department of Catalysis, Center for Physical Sciences and Technology, Vilnius LT 01108 (Lithuania); Tamašauskaitė-Tamašiūnaitė, L.; Jablonskienė, J.; Semaško, M.; Vaičiūnienė, J. [Department of Catalysis, Center for Physical Sciences and Technology, Vilnius LT 01108 (Lithuania); Vaitkus, R. [Faculty of Chemistry, Vilnius University, Vilnius LT 03225 (Lithuania); Norkus, E. [Department of Catalysis, Center for Physical Sciences and Technology, Vilnius LT 01108 (Lithuania)

    2016-03-01

    In the present study the graphene supported platinum–cobalt nanoparticles were prepared via microwave synthesis. The composition of prepared catalysts was examined by Inductively Coupled Plasma Optical Emission Spectroscopy. The shape and size of catalyst particles were determined by Transmission Electron Microscopy. The electrocatalytic activity of the graphene supported platinum–cobalt nanoparticles was investigated towards the electro-oxidation of methanol in an alkaline medium. It has been found that the graphene supported platinum–cobalt nanoparticles having the Pt:Co molar ratio 1:7 show the highest activity towards the electro-oxidation of methanol among the catalysts with the Pt:Co molar ratios equal to 1:1 and 1:44, graphene supported bare Co and Pt/C catalysts. - Highlights: • Preparation of graphene supported Pt-Co nanoparticles by microwave synthesis. • Electrocatalysts for oxidation of methanol. • Higher activity of PtCo/graphene towards methanol oxidation.

  19. Thermodynamic models to predict gas-liquid solubilities in the methanol synthesis, the methanol-higher alcohol synthesis, and the Fischer-Tropsch synthesis via gas-slurry processes

    NARCIS (Netherlands)

    Breman, B.B; Beenackers, A.A C M

    1996-01-01

    Various thermodynamic models were tested concerning their applicability to predict gas-liquid solubilities, relevant for synthesis gas conversion to methanol, higher alcohols, and hydrocarbons via gas-slurry processes. Without any parameter optimization the group contribution equation of state

  20. Low-temperature metal-oxide thin-film transistors formed by directly photopatternable and combustible solution synthesis.

    Science.gov (United States)

    Rim, You Seung; Lim, Hyun Soo; Kim, Hyun Jae

    2013-05-01

    We investigated the formation of ultraviolet (UV)-assisted directly patternable solution-processed oxide semiconductor films and successfully fabricated thin-film transistors (TFTs) based on these films. An InGaZnO (IGZO) solution that was modified chemically with benzoylacetone (BzAc), whose chelate rings decomposed via a π-π* transition as result of UV irradiation, was used for the direct patterning. A TFT was fabricated using the directly patterned IGZO film, and it had better electrical characteristics than those of conventional photoresist (PR)-patterned TFTs. In addition, the nitric acid (HNO3) and acetylacetone (AcAc) modified In2O3 (NAc-In2O3) solution exhibited both strong UV absorption and high exothermic reaction. This method not only resulted in the formation of a low-energy path because of the combustion of the chemically modified metal-oxide solution but also allowed for photoreaction-induced direct patterning at low temperatures.

  1. An in situ infrared study of dimethyl carbonate synthesis from carbon dioxide and methanol over zirconia

    International Nuclear Information System (INIS)

    Jung, Kyeong Taek; Bell, Alexis T.

    2001-01-01

    The mechanism of dimethyl carbonate (DMC) synthesis from methanol and carbon dioxide over monoclinic zirconia has been investigated using in situ infrared spectroscopy. The dissociative adsorption of methanol occurs more slowly than the adsorption of carbon dioxide, but the species formed from methanol are bound more strongly. Upon adsorption, the oxygen atom of methanol binds to coordinately unsaturated Zr4+ cations present at the catalyst surface. Rapid dissociation of the adsorbed methanol leads to the formation of a methoxide group (Zr-OCH3) and the release of a proton, which reacts with a surface hydroxyl group to produce water. Carbon dioxide inserts in the Zr-O bond of the methoxide to form a mondentate methyl carbonate group (Zr-OC(O)OCH3). This process is facilitated by the interactions of C and O atoms in CO2 with Lewis acid-base pairs of sites (Zr4+O2-) on the surface of the catalyst. Methyl carbonate species can also be produced via the reaction of methanol with carbon dioxide adsorbed in the form of bicarbonate species with methanol, a process that results in the transfer of a methyl group to the carbonate and restores a hydroxyl group to the zirconia surface. The decomposition of DMC on monoclinic zirconia has also been investigated and has been observed to occur via the reverse of the processes described for the synthesis of DMC

  2. Facile Low Temperature Hydrothermal Synthesis of BaTiO3 Nanoparticles Studied by In Situ X-ray Diffraction

    Directory of Open Access Journals (Sweden)

    Ola G. Grendal

    2018-06-01

    Full Text Available Ferroelectric materials are crucial for today’s technological society and nanostructured ferroelectric materials are important for the downscaling of devices. Controlled and reproducible synthesis of these materials are, therefore, of immense importance. Hydrothermal synthesis is a well-established synthesis route, with a large parameter space for optimization, but a better understanding of nucleation and growth mechanisms is needed for full utilization and control. Here we use in situ X-ray diffraction to follow the nucleation and growth of BaTiO3 formed by hydrothermal synthesis using two different titanium precursors, an amorphous titania precipitate slurry and a Ti-citric acid complex solution. Sequential Rietveld refinement was used to extract the time dependency of lattice parameters, crystallite size, strain, and atomic displacement parameters. Phase pure BaTiO3 nanoparticles, 10–15 nm in size, were successfully synthesized at different temperatures (100, 125, and 150 °C from both precursors after reaction times, ranging from a few seconds to several hours. The two precursors resulted in phase pure BaTiO3 with similar final crystallite size. Finally, two different growth mechanisms were revealed, where the effect of surfactants present during hydrothermal synthesis is discussed as one of the key parameters.

  3. Low-Temperature Synthesis of Anatase TiO2 Nanoparticles with Tunable Surface Charges for Enhancing Photocatalytic Activity

    Science.gov (United States)

    Li, Ye; Qin, Zhenping; Guo, Hongxia; Yang, Hanxiao; Zhang, Guojun; Ji, Shulan; Zeng, Tingying

    2014-01-01

    In this work, the positively or negatively charged anatase TiO2 nanoparticles were synthesized via a low temperature precipitation-peptization process (LTPPP) in the presence of poly(ethyleneimine) (PEI) and poly(sodium4- styrenesulfonate) (PSS). X-ray diffraction (XRD) pattern and high-resolution transmission electron microscope (HRTEM) confirmed the anatase crystalline phase. The charges of the prepared TiO2, PEI-TiO2 and PSS-TiO2 nanoparticles were investigated by zeta potentials. The results showed that the zeta potentials of PEI-TiO2 nanoparticles can be tuned from +39.47 mV to +95.46 mV, and that of PSS-TiO2 nanoparticles can be adjusted from −56.63 mV to −119.32 mV. In comparison with TiO2, PSS-TiO2 exhibited dramatic adsorption and degradation of dye molecules, while the PEI modified TiO2 nanoparticles showed lower photocatalytic activity. The photocatalytic performances of these charged nanoparticles were elucidated by the results of UV-vis diffuse reflectance spectra (DRS) and the photoluminescence (PL) spectra, which indicated that the PSS-TiO2 nanoparticles showed a lower recombination rate of electron-hole pairs than TiO2 and PEI-TiO2. PMID:25506839

  4. Low temperature synthesis of Zn{sub 2}GeO{sub 4} nanorods and their photoluminescence

    Energy Technology Data Exchange (ETDEWEB)

    Tsai, Meng-Yen [Department of Materials Science and Engineering, National Tsing Hua University, Hsinchu 300, Taiwan (China); Instrument Technology Research Center, National Applied Research Laboratories, Hsinchu 300, Taiwan (China); Huang, Sheng-Hsin [Department of Materials Science and Engineering, National Tsing Hua University, Hsinchu 300, Taiwan (China); Perng, Tsong-Pyng, E-mail: tpperng@mx.nthu.edu.tw [Department of Materials Science and Engineering, National Tsing Hua University, Hsinchu 300, Taiwan (China); Department of Chemical Engineering and Materials Science, Yuan Ze University, Chungli 320, Taiwan (China)

    2013-04-15

    Zn{sub 2}GeO{sub 4} nanorods were synthesized using a simple reflux method. The product with 0.05 M Zn{sub 2}GeO{sub 4} is an aggregation of short nanorods with the diameter ranging from 30 to 50 nm. If the Zn{sub 2}GeO{sub 4} molarity was increased, the nanorods became longer and aggregated as bundles. An intense white-bluish photoluminescence (PL) was observed from these nanorods, and the PL band can be dissolved into four Gaussian peaks that are associated with the native defects. Since the PL intensity of the nanorods is comparable to that of sintered particles, this reflux method provides a time- and energy-efficient route to prepare Zn{sub 2}GeO{sub 4} phosphor. -- Highlights: ► Zn{sub 2}GeO{sub 4} nanorods were prepared by a simple refluxing method at low temperature without any surfactants. ► The morphologies and crystal structures of Zn{sub 2}GeO{sub 4} growth were studied from beginning to the end (0 min to 3 h). ► The photoluminescence of Zn{sub 2}GeO{sub 4} synthesized by different methods was studied.

  5. Low Temperature Synthesis of Fluorine-Doped Tin Oxide Transparent Conducting Thin Film by Spray Pyrolysis Deposition.

    Science.gov (United States)

    Ko, Eun-Byul; Choi, Jae-Seok; Jung, Hyunsung; Choi, Sung-Churl; Kim, Chang-Yeoul

    2016-02-01

    Transparent conducting oxide (TCO) is widely used for the application of flat panel display like liquid crystal displays and plasma display panel. It is also applied in the field of touch panel, solar cell electrode, low-emissivity glass, defrost window, and anti-static material. Fluorine-doped tin oxide (FTO) thin films were fabricated by spray pyrolysis of ethanol-added FTO precursor solutions. FTO thin film by spray pyrolysis is very much investigated and normally formed at high temperature, about 500 degrees C. However, these days, flexible electronics draw many attentions in the field of IT industry and the research for flexible transparent conducting thin film is also required. In the industrial field, indium-tin oxide (ITO) film on polymer substrate is widely used for touch panel and displays. In this study, we investigated the possibility of FTO thin film formation at relatively low temperature of 250 degrees C. We found out that the control of volume of input precursor and exhaust gases could make it possible to form FTO thin film with a relatively low electrical resistance, less than 100 Ohm/sq and high optical transmittance about 88%.

  6. Low temperature N,N-dimethylformamide-assisted synthesis and characterization of anatase-rutile biphasic nanostructured titania

    Energy Technology Data Exchange (ETDEWEB)

    Estruga, M; Domenech, X; Ayllon, J A [Departament de Quimica, Universitat Autonoma de Barcelona, Campus UAB, E-08193 Bellaterra (Spain); Domingo, C [Institut de Ciencia dels Materials de Barcelona (CSIC), Campus UAB, E-08193 Bellaterra (Spain)], E-mail: joseantonio.ayllon@uab.es, E-mail: mestruga@qf.uab.cat

    2009-03-25

    Anatase and rutile biphasic nanostructured titania (TiO{sub 2}) has been synthesized via hydrolysis of titanium tetraisopropoxide in an aqueous solution of hydrobromic acid (HBr) and N,N-dimethylformamide (DMF) at 80 deg. C for 16 h. The presence of DMF, which was partially hydrolyzed during the process, determined the formation of a biphasic material. Powder x-ray diffraction showed the presence of both anatase and rutile titania phases in a ratio of approx. 1:1. Transmission electron microscope analysis showed that rutile was present as radial flower-like nanorods, which were surrounded by anatase spherical nanoparticles of 5 nm diameter. Low temperature nitrogen adsorption-desorption analysis showed the characteristic hysteresis loop of a mesoporous material. Specific surface area reached a value of 120 m{sup 2} g{sup -1} and the average pore diameter was 50 A. X-ray photoelectron spectroscopic analysis revealed that interstitial nitrogen was incorporated (0.35 at.%) during the annealing process. According to ultraviolet (UV)-visible diffuse reflectance spectroscope characterization, the N-doping caused a bandgap reduction from 3.0 to 2.9 eV. Photocatalytic activity of the material was tested for the degradation of methylene blue, methyl orange and 4-nitrophenol under near-UV and visible light radiation.

  7. Low temperature synthesis of seed mediated CuO bundle of nanowires, their structural characterisation and cholesterol detection.

    Science.gov (United States)

    Ibupoto, Z H; Khun, K; Liu, X; Willander, M

    2013-10-01

    In this study, we have successfully synthesised CuO bundle of nanowires using simple, cheap and low temperature hydrothermal growth method. The growth parameters such as precursor concentration and time for duration of growth were optimised. The field emission scanning electron microscopy (FESEM) has demonstrated that the CuO bundles of nanowires are highly dense, uniform and perpendicularly oriented to the substrate. The high resolution transmission electron microscopy (HRTEM) has demonstrated that the CuO nanostructures consist of bundle of nanowires and their growth pattern is along the [010] direction. The X-ray diffraction (XRD) technique described that CuO bundle of nanowires possess the monoclinic crystal phase. The surface and chemical composition analyses were carried out with X-ray photoelectron spectroscopy (XPS) technique and the obtained results suggested the pure crystal state of CuO nanostructures. In addition, the CuO nanowires were used for the cholesterol sensing application by immobilising the cholesterol oxidase through electrostatic attraction. The infrared reflection absorption spectroscopy study has also revealed that CuO nanostructures are consisting of only CuO bonding and has also shown the possible interaction of cholesterol oxidase with the sharp edge surface of CuO bundle of nanowires. The proposed cholesterol sensor has demonstrated the wide range of detection of cholesterol with good sensitivity of 33.88±0.96 mV/decade. Moreover, the CuO bundle of nanowires based sensor electrode has revealed good repeatability, reproducibility, stability, selectivity and a fast response time of less than 10s. The cholesterol sensor based on the immobilised cholesterol oxidase has good potential applicability for the determination of cholesterol from the human serum and other biological samples. Copyright © 2013 Elsevier B.V. All rights reserved.

  8. Low-temperature synthesis and characterization of helical carbon fibers by one-step chemical vapour deposition

    Energy Technology Data Exchange (ETDEWEB)

    Jin, Yongzhong [Department of Materials and Chemistry Engineering, Sichuan University of Science and Engineering, 643000 Zigong, Sichuan (China); Chen, Jian, E-mail: wuhangzs@163.com [Department of Materials and Chemistry Engineering, Sichuan University of Science and Engineering, 643000 Zigong, Sichuan (China); Fu, Qingshan [Department of Materials and Chemistry Engineering, Sichuan University of Science and Engineering, 643000 Zigong, Sichuan (China); Li, Binghong [China Rubber Group Carbon Black Industry Research and Design Institute, 643000 Zigong, Sichuan (China); Zhang, Huazhi; Gong, Yong [Department of Materials and Chemistry Engineering, Sichuan University of Science and Engineering, 643000 Zigong, Sichuan (China)

    2015-01-01

    Graphical abstract: - Highlights: • HCNFs were synthesized by one-step CVD using cupric tartrate as a catalyst at temperature below 500 °C. • The synthesis of HCNFs is highly temperature-dependent at the synthesis temperature of 280–480 °C. • The addition of HCNFs makes a noticeable contribution to the reinforcement of NR/CB system. - Abstract: Helical carbon fibers (HCNFs) were synthesized by one-step chemical vapour deposition using cupric tartrate as a catalyst at temperature below 500 °C. The bound rubber of natural rubber (NR)/HCNFs were also prepared in this study. The results of thermogravimetry–differential scanning calorimetry (TG/DSC) for cupric tartrate nanoparticles show that the transformation of C{sub 4}H{sub 4}CuO{sub 6} → Cu reaction occurs at ∼250–310 °C. The characterization of scanning electron microscopy (SEM), transmission electron microscope (TEM), X-ray diffraction (XRD) and Raman spectrum for the synthesized products confirms that the synthesis of HCNFs is highly temperature-dependent. The straight fibers with the fiber diameter of 100–400 nm are obtained at 280 °C and HCNFs can be synthesized at higher temperature, with the coil diameter of 0.5–1 μm and fiber diameter of 100–200 nm at 380 °C, and the coil diameter of ∼100 nm and fiber diameter of ∼80 nm at 480 °C. The maximum of the bound-rubber content (37%) can be obtained with the addition of 100 wt.% HCNFs in NR, which indicates that the coiled configuration of HCNFs makes a noticeable contribution to the reinforcement of NR/CB system.

  9. Low-temperature synthesis and characterization of helical carbon fibers by one-step chemical vapour deposition

    International Nuclear Information System (INIS)

    Jin, Yongzhong; Chen, Jian; Fu, Qingshan; Li, Binghong; Zhang, Huazhi; Gong, Yong

    2015-01-01

    Graphical abstract: - Highlights: • HCNFs were synthesized by one-step CVD using cupric tartrate as a catalyst at temperature below 500 °C. • The synthesis of HCNFs is highly temperature-dependent at the synthesis temperature of 280–480 °C. • The addition of HCNFs makes a noticeable contribution to the reinforcement of NR/CB system. - Abstract: Helical carbon fibers (HCNFs) were synthesized by one-step chemical vapour deposition using cupric tartrate as a catalyst at temperature below 500 °C. The bound rubber of natural rubber (NR)/HCNFs were also prepared in this study. The results of thermogravimetry–differential scanning calorimetry (TG/DSC) for cupric tartrate nanoparticles show that the transformation of C 4 H 4 CuO 6 → Cu reaction occurs at ∼250–310 °C. The characterization of scanning electron microscopy (SEM), transmission electron microscope (TEM), X-ray diffraction (XRD) and Raman spectrum for the synthesized products confirms that the synthesis of HCNFs is highly temperature-dependent. The straight fibers with the fiber diameter of 100–400 nm are obtained at 280 °C and HCNFs can be synthesized at higher temperature, with the coil diameter of 0.5–1 μm and fiber diameter of 100–200 nm at 380 °C, and the coil diameter of ∼100 nm and fiber diameter of ∼80 nm at 480 °C. The maximum of the bound-rubber content (37%) can be obtained with the addition of 100 wt.% HCNFs in NR, which indicates that the coiled configuration of HCNFs makes a noticeable contribution to the reinforcement of NR/CB system

  10. Low temperature synthesis and characterization of Na–M–(O)–F phases with M=Ti, V

    Energy Technology Data Exchange (ETDEWEB)

    Nava-Avendaño, Jessica [Institut de Ciència de Materials de Barcelona (ICMAB-CSIC), Campus UAB, E-08193 Bellaterra, Catalonia (Spain); Ayllón, José A. [Departament de Química, Universitat Autònoma de Barcelona, Campus UAB, E-08193 Bellaterra, Catalonia (Spain); Frontera, Carlos; Oró-Solé, Judith [Institut de Ciència de Materials de Barcelona (ICMAB-CSIC), Campus UAB, E-08193 Bellaterra, Catalonia (Spain); Estruga, Marc [Departament de Química, Universitat Autònoma de Barcelona, Campus UAB, E-08193 Bellaterra, Catalonia (Spain); Molins, Elies [Institut de Ciència de Materials de Barcelona (ICMAB-CSIC), Campus UAB, E-08193 Bellaterra, Catalonia (Spain); Palacín, M. Rosa, E-mail: rosa.palacin@icmab.es [Institut de Ciència de Materials de Barcelona (ICMAB-CSIC), Campus UAB, E-08193 Bellaterra, Catalonia (Spain)

    2015-03-15

    Na{sub 5}Ti{sub 3}O{sub 3}F{sub 11} was prepared by the microwave assisted method, and presents a chiolite related structure with cell parameters a=10.5016(5), b=10.4025(5), and c=10.2911(5) Å and Cmca (no. 64) space group. From solvothermal synthesis at 100 °C the cryolite Na{sub 3−δ}VO{sub 1−δ}F{sub 5+δ} was prepared, which crystallizes in the monoclinic system with a=5.5403(2), b=5.6804(2), c=7.9523(2) Å, β=90.032(7)° cell parameters and P2{sub 1}/n (no. 14) space group. Under similar synthesis conditions but with higher HF concentration the chiolite-type phase Na{sub 5−δ}V{sub 3}F{sub 14} was achieved, which exhibits a=10.5482(2), b=10.4887(1) and c=10.3243(1) Å cell parameters and Cmc2{sub 1} (no. 36) space group. A single crystal also having the chiolite structure was synthesized at 200 °C which exhibits tetragonal symmetry (a=7.380(3) and c=10.381(11) Å and space group P4{sub 2}2{sub 1}2 (no. 94)). Bond valence sum indicates that it contains V{sup 4+} and therefore can be formulated as Na{sub 5}V{sub 3}O{sub 3}F{sub 11}. - Graphical abstract: Na{sub 5}M{sub 3}(O,F){sub 14} with M=Ti and V having chiolite structure and Na{sub 3−δ}VO{sub 1−δ}F{sub 5+δ} cryolite were prepared by means of microwave-assisted and solvothermal synthesis. - Highlights: • Na{sub 5}Ti{sub 3}O{sub 3}F{sub 11} chiolite was prepared by a microwave assisted method and characterized. • Na{sub 3−δ}VO{sub 1−δ}F{sub 5+δ} and Na{sub 5−δ}V{sub 3}F{sub 14} were prepared by solvothermal synthesis. • The compounds were structurally characterized by diffraction techniques. • O/F distribution was estimated by applying Pauling’s second rule.

  11. Spectroscopic investigation on the chemical forms of Cu during the synthesis of zeolite X at low temperature

    International Nuclear Information System (INIS)

    Terzano, Roberto; Spagnuolo, Matteo; Medici, Luca; Tateo, Fabio; Vekemans, Bart; Janssens, Koen; Ruggiero, Pacifico

    2006-01-01

    The direct synthesis of zeolites in polluted soils has proved to be a promising process for the stabilization of metals inside these minerals. Nevertheless, more detailed information about this process is still needed in order to better foresee the fate of metals in treated soils. In this work, zeolite X has been synthesized under alkaline conditions in an aqueous solution containing 2500 mg kg -1 of Cu, starting from Na silicate and Al hydroxide at 60 deg. C. Aluminium, Si and Cu concentrations in the aqueous phase, during zeolite synthesis, were measured over a period of 160 h. The solid products have been characterized over time by XRD, SEM-EDX, ESR, FT-IR, and synchrotron radiation X-ray microbeam absorption near edge structure (μ-XANES) and extended X-ray absorption fine structure (μ-EXAFS) spectroscopy. It appears that the marked reduction of Cu concentration in solution is not only due to a simple precipitation effect, but also to processes connected with the formation of zeolite X which could entrap, inside its porous structure, nano- or micro-occlusions of precipitated Cu hydroxides and/or oxides. In addition, EXAFS observations strengthen the hypothesis of the presence of different Cu phases even at a short-range molecular level and suggest that some of these occlusions could be even bound to the zeolite framework. The results suggest that zeolite formation could be used to reduce the availability of metals in polluted soils

  12. Novel Synthesis of Ultra-Small Dextran Coated Maghemite Nanoparticles for MRI and CT Contrast Agents via a Low Temperature Co-Precipitation Reaction.

    Science.gov (United States)

    Rabias, Ioannis; Fardis, Michael; Kehagias, Thomas; Kletsas, Dimitris; Pratsinis, Harris; Tsitrouli, Danai; Maris, Thomas G; Papavassiliou, George

    2015-01-01

    Ultra-small dextran coated maghemite nanoparticles are synthesized via a low temperature modified co-precipitation method. A monoethylene glycol/water solution of 1:1 molar ratios and a fixed apparatus is used at a constant temperature of 5-10 degrees C. The growth of nanoparticles is prohibited due to low temperature synthesis and differs from usual thermal decomposition methods via Ostwald ripening. Strict temperature control and reaction timing of less than 20 minutes are essential to maintain narrow distribution in particle size. These nanoparticles are water-dispersible and biocompatible by capping with polyethylene glycol ligands. The aqueous suspensions are tested for cytotoxic activity on normal human skin fibroblasts. There is no reduction of the cells' viability at any concentration tested, the highest being 1% v/v of the suspension in culture medium, corresponding to the highest concentrations to be administered in vivo. Initial comparison with a T1 MRI contrast agent in sale shows that maghemite nanoparticles exhibit high r1 and r2 relaxivities in MRI tomography and strong contrast in computed tomography, demonstrating that these nanoparticles can be efficient T1, T2 and CT contrast agents.

  13. Surface decoration through electrostatic interaction leading to enhanced reactivity: Low temperature synthesis of nanostructured chromium borides (CrB and CrB2)

    International Nuclear Information System (INIS)

    Menaka,; Kumar, Bharat; Kumar, Sandeep; Ganguli, A.K.

    2013-01-01

    The present study describes a novel low temperature route at ambient pressure for the synthesis of nanocrystalline chromium borides (CrB and CrB 2 ) without using any flux or additives. The favorable and intimate mixing of nanoparticles of chromium acetate (Cr source) and boron forms an active chromium–boron precursor which decomposes at much lower temperature (400 °C) to form CrB (which is ∼1000 °C less than the known ambient pressure synthesis). The chromium acetate nanoparticles (∼5 nm) decorate the larger boron particles (150–200 nm) due to electrostatic interactions resulting from opposing surface charges of boron (zeta potential:+48.101 mV) and chromium acetate (zeta potential:−4.021 mV) in ethanolic medium and is evident in the TEM micrographs. The above method leads to the formation of pure CrB film like structure at 400 °C and nanospheres (40–60 nm) at 600 °C. Also, chromium diboride (CrB 2 ) nanoparticles (25 nm) could be obtained at 1000 °C. - Graphical abstract: Variation of surface charge of reactants, precursor and the products, chromium borides (CrB and CrB 2 ). Highlights: ► Novel borothermal reduction process for synthesis of chromium boride. ► Significant lowering of reaction temperature to obtain nanocrystalline chromium boride. ► Enhanced reactivity due to appropriate surface interactions

  14. Low-temperature synthesis of Li{sub 7}La{sub 3}Zr{sub 2}O{sub 12} with cubic garnet-type structure

    Energy Technology Data Exchange (ETDEWEB)

    Xie, Hui [Texas Materials Institute, ETC 9.184, University of Texas at Austin, Austin, TX 78712 (United States); Li, Yutao [Texas Materials Institute, ETC 9.184, University of Texas at Austin, Austin, TX 78712 (United States); State Key Laboratory of New Ceramics and Fine Processing, Department of Materials Science and Engineering, Tsinghua University, Beijing 100084 (China); Goodenough, John B., E-mail: jgoodenough@mail.utexas.edu [Texas Materials Institute, ETC 9.184, University of Texas at Austin, Austin, TX 78712 (United States)

    2012-05-15

    Highlights: Black-Right-Pointing-Pointer One-step synthesis and its optimization of cubic garnet Li{sub 7}La{sub 3}Zr{sub 2}O{sub 12} at 750 Degree-Sign C. Black-Right-Pointing-Pointer Instability above 800 Degree-Sign C of the Al-free cubic Li{sub 7}La{sub 3}Zr{sub 2}O{sub 12}. Black-Right-Pointing-Pointer Li{sup +}-ion conductivity without adventitious Al{sup 3+}. -- Abstract: In this paper, we report the direct synthesis of Li{sub 7}La{sub 3}Zr{sub 2}O{sub 12} with the cubic garnet-type structure at low temperature with a lattice constant of 13.0035 Angstrom-Sign . The synthesis condition is optimized to be at 750 Degree-Sign C for 8 h with 30 wt% excess lithium salt. No intermediate grinding was involved in this straightforward route. Without the adventitious of Al{sup 3+}, the cubic Li{sub 7}La{sub 3}Zr{sub 2}O{sub 12} is unstable above 800 Degree-Sign C and has an ionic conductivity of the order of 10{sup -6} S cm{sup -1}.

  15. Molten salts activated by high-energy milling: A useful, low-temperature route for the synthesis of multiferroic compounds

    Energy Technology Data Exchange (ETDEWEB)

    Hernández-Ramírez, Anayantzin; Martínez-Luévanos, Antonia [Facultad de Ciencias Químicas, Universidad Autónoma de Coahuila, V. Carranza s/n, Saltillo, Coahuila 25280 (Mexico); Fuentes, Antonio F. [CINVESTAV Unidad Saltillo, Apdo. Postal 663, Saltillo, Coahuila 25000 (Mexico); Earth and Environmental Science, University of Michigan, 3514 C.C. Little Building, 1100 N. University Avenue, Ann Arbor, MI 48109-1005 (United States); Nelson, Anna-Gay D.; Ewing, Rodney C. [Earth and Environmental Science, University of Michigan, 3514 C.C. Little Building, 1100 N. University Avenue, Ann Arbor, MI 48109-1005 (United States); Montemayor, Sagrario M., E-mail: smmontemayor@gmail.com [Facultad de Ciencias Químicas, Universidad Autónoma de Coahuila, V. Carranza s/n, Saltillo, Coahuila 25280 (Mexico); Earth and Environmental Science, University of Michigan, 3514 C.C. Little Building, 1100 N. University Avenue, Ann Arbor, MI 48109-1005 (United States)

    2014-01-25

    Highlights: • The synthesis route purposed demonstrates the formation of BiFeO{sub 3} at only 500 °C. • The magnetic and ferroelectric properties are comparable to those of bulk BiFeO{sub 3}. • By this route, several phases in Bi{sub 1−x}La{sub x}FeO{sub 3} system are obtained at only 500 °C. • The route developed here could be useful to synthesize other perovskite-type oxides. -- Abstract: There are only a few multiferroic compounds, among which BiFeO{sub 3} is the most important. Research the synthesis of bismuth ferrite, with novel and improved magnetic and electrical properties, has been mainly based on the use of hydrothermal or sol gel methods. However, these methods require either rather extreme conditions or several steps for synthesis. We demonstrate that the use of molten salts, activated by high energy milling, results in pure nanometric BiFeO{sub 3}, LaFeO{sub 3} and intermediate phases in the Bi{sub 1−x}La{sub x}FeO{sub 3} system. The chemical reagents used are Bi(NO{sub 3}){sub 3}⋅5H{sub 2}O, La(NO{sub 3}){sub 3}⋅6H{sub 2}O, Fe(NO{sub 3}){sub 3}⋅9H{sub 2}O and NaOH. A brief milling process of the reagents creates an amorphous precursor and crystalline NaNO{sub 3}. The thermal treatment of the precursors, at 500 °C for two hours, produces a crystalline mixture of Bi{sub 1−x}La{sub x}FeO{sub 3} and NaNO{sub 3}. Simple washing eliminates the NaNO{sub 3}. The characterization of intermediates and final products, through thermal analysis, X-ray diffraction and scanning electronic microscopy, allows the inference of possible mechanism. In addition, vibrating sample magnetometry (VSM) and ferroelectric tests show the typical magnetic and electric polarization loops characteristic of these materials even when formed at the nano-scale.

  16. Lanthanide ions doped Y2Sn2O7 nano-particles: low temperature synthesis and photoluminescence study

    International Nuclear Information System (INIS)

    Nigam, Sandeep; Sudarsan, V.; Vatsa, R.K.

    2008-01-01

    During the past decade, pyrochlore-type oxides (A 2 B 2 O 7 ) have emerged as important host matrices for lanthanide doped luminescent materials due to their higher thermal stability. Up to now, conventional solid-state reaction is the most commonly used synthetic method for preparation, of rare-earth pyrochlore oxides. This synthesis route employs a solid-state reaction of metal-oxide with appropriate rare-earth oxides at high temperature (>1200 deg C) for a long time (several days). However, in present work, Y 2 Sn 2 O 7 nanoparticles co-doped with lanthanide ions Tb 3+ and Ce 3+ were prepared based on the urea hydrolysis of Y 3+ , Sn 4+ , and Ln 3+ in ethylene glycol medium at 150 deg C followed by heating at 500, 700 and 900 deg C

  17. Controllable synthesis of spindle-like ZnO nanostructures by a simple low-temperature aqueous solution route

    International Nuclear Information System (INIS)

    Lu Hongxia; Zhao Yunlong; Yu Xiujun; Chen Deliang; Zhang Liwei; Xu Hongliang; Yang Daoyuan; Wang Hailong; Zhang Rui

    2011-01-01

    Spindle-like ZnO nanostructures were successfully synthesized through direct precipitation of zinc acetate aqueous solution at 60 deg. C. Phase structure, morphology and microstructure of the products were investigated by X-ray diffraction, TG-DTA, FTIR and field emission scanning electron microscopy (FESEM). Result showed that hexagonal wurtzite structure ZnO nanostructures with about 100 nm in diameter and 100-200 nm in length were obtained. HMTA acted as a soft template in the process and played an important role in the formation of spindle-like ZnO nanostructures. Meanwhile, different morphologies were also obtained by altering synthetic temperature, additional agents and the ratios of Zn 2+ /OH - . Possible mechanism for the variations of morphology with synthesis parameters was also discussed in this paper.

  18. Antagonistic effects of high and low temperature pretreatments on the germination and pregermination ethylene synthesis of lettuce seeds.

    Science.gov (United States)

    Burdett, A N

    1972-08-01

    Red light-induced germination of Grand Rapids lettuce seeds (Lactuca sativa L.) incubated at 20 C was inhibited if the seeds were first imbibed at 30 C for 36 hours. This effect was counteracted by exogenous ethylene and associated with a reduction in the rate at which the seeds produced ethylene throughout the pregermination period. A chilling treatment reversed the effect of a prior imbibition at 30 C on both germination and ethylene production. The possibility that the pretreatments influence germination through their effects on ethylene production is discussed.Other evidence presented indicates that the inability of seeds to germinate at supraoptimal temperature is not due either to a rapid loss of far red-absorbing phytochrome or to an inadequate capacity for ethylene synthesis. It was also shown that a chilling treatment potentiated germination at high temperature without affecting the ethylene synthetic capacity of the seeds.

  19. Support Functionalization To Retard Ostwald Ripening in Copper Methanol Synthesis Catalysts

    NARCIS (Netherlands)

    van den Berg, Roy; Parmentier, Tanja E.; Elkjaer, Christian F.; Gommes, Cedric J.; Sehested, Jens; Helveg, Stig; de Jongh, Petra E.; de Jong, Krijn P.

    A main reason for catalyst deactivation in supported catalysts for methanol synthesis is copper particle growth. We have functionalized the support surface in order to suppress the formation and/or transport of mobile copper species and thereby catalyst deactivation. A Stober silica support was

  20. Methanol synthesis in a countercurrent gas-solid-solid trickle flow reactor. An experimental study

    NARCIS (Netherlands)

    Kuczynski, M.; Oyevaar, M.H.; Pieters, R.T.; Westerterp, K.R.

    1987-01-01

    The synthesis of methanol from CO and H2 was executed in a gas-solid-solid trickle flow reactor. The reactor consisted of three tubular reactor sections with cooling sections in between. The catalyst was Cu on alumina, the adsorbent was a silica-alumina powder and the experimental range 498–523 K,

  1. Methanol Metabolism in Yeasts : Regulation of the Synthesis of Catabolic Enzymes

    NARCIS (Netherlands)

    Egli, Th.; Dijken, J.P. van; Veenhuis, M.; Harder, W.; Fiechter, A.

    1980-01-01

    The regulation of the synthesis of four dissimilatory enzymes involved in methanol metabolism, namely alcohol oxidase, formaldehyde dehydrogenase, formate dehydrogenase and catalase was investigated in the yeasts Hansenula polymorpha and Kloeckera sp. 2201. Enzyme profiles in cell-free extracts of

  2. Synthesis of InGaZnO{sub 4} nanoparticles using low temperature multistep co-precipitation method

    Energy Technology Data Exchange (ETDEWEB)

    Wu, Ming-Chung, E-mail: mingchungwu@mail.cgu.edu.tw; Hsiao, Kai-Chi; Lu, Hsin-Chun

    2015-07-15

    Indium gallium zinc oxide (InGaZnO{sub 4}, IGZO) has attracted explosive growth in investigations over the last decades as an important material in the thin-film transistor. In this study, the various nitrate precursors, including indium nitrate, gallium nitrate, and zinc nitrate, were prepared from the various metals dissolved in nitric acid. Then, we used these nitrate precursors to synthesize the IGZO precursor powder by the multistep co-precipitation method. The synthesis parameters of the co-precipitation method, such as reaction temperature, pH value and reaction time, were controlled precisely to prepare the high quality IGZO precursor powder. Finally, IGZO precursor powder was calcined at 900 °C. Then, the microstructure, the crystalline structure, the particle size distribution and specific surface area of calcined IGZO precursor powder were characterized by electron transmission microscopy, X-ray diffraction technique, dynamic light scattering method and the surface area and porosimetry analyzer, respectively. The relative density of IGZO tablet sintered at 1200 °C for 12 h is as high as 97.30%, and it showed highly InGaZnO{sub 4} crystalline structure and the large grain size. The IGZO nanoparticles developed in our study has the potential for the high quality target materials used in the application of electronic devices. - Graphical abstract: Display Omitted - Highlights: • InGaZnO{sub 4} (IGZO) nanoparticle was synthesized by multistep co-precipitation method. • The synthesis parameters were controlled precisely to prepare high quality powder. • The relative density of highly crystalline IGZO tablet is as high as 97.30%. • IGZO tablet exhibited highly crystalline structure and the large grain size.

  3. Synthesis of InGaZnO4 nanoparticles using low temperature multistep co-precipitation method

    International Nuclear Information System (INIS)

    Wu, Ming-Chung; Hsiao, Kai-Chi; Lu, Hsin-Chun

    2015-01-01

    Indium gallium zinc oxide (InGaZnO 4 , IGZO) has attracted explosive growth in investigations over the last decades as an important material in the thin-film transistor. In this study, the various nitrate precursors, including indium nitrate, gallium nitrate, and zinc nitrate, were prepared from the various metals dissolved in nitric acid. Then, we used these nitrate precursors to synthesize the IGZO precursor powder by the multistep co-precipitation method. The synthesis parameters of the co-precipitation method, such as reaction temperature, pH value and reaction time, were controlled precisely to prepare the high quality IGZO precursor powder. Finally, IGZO precursor powder was calcined at 900 °C. Then, the microstructure, the crystalline structure, the particle size distribution and specific surface area of calcined IGZO precursor powder were characterized by electron transmission microscopy, X-ray diffraction technique, dynamic light scattering method and the surface area and porosimetry analyzer, respectively. The relative density of IGZO tablet sintered at 1200 °C for 12 h is as high as 97.30%, and it showed highly InGaZnO 4 crystalline structure and the large grain size. The IGZO nanoparticles developed in our study has the potential for the high quality target materials used in the application of electronic devices. - Graphical abstract: Display Omitted - Highlights: • InGaZnO 4 (IGZO) nanoparticle was synthesized by multistep co-precipitation method. • The synthesis parameters were controlled precisely to prepare high quality powder. • The relative density of highly crystalline IGZO tablet is as high as 97.30%. • IGZO tablet exhibited highly crystalline structure and the large grain size

  4. Facile and low temperature route to synthesis of CuS nanostructure in mesoporous material by solvothermal method.

    Science.gov (United States)

    Sohrabnezhad, Sh; Zanjanchi, M A; Hosseingholizadeh, S; Rahnama, R

    2014-04-05

    The synthesis of CuS nanomaterial in MCM-41 matrix has been realized by chemical synthesis between MCM-41, copper sulfate pentahydrate and thiourea via a solvothermal method in ethylene glycol and water, separately. X-ray diffraction analysis (XRD), diffuse reflectance spectroscopy (DRS), scanning electron microscopy (SEM), transmission electron microscopy (TEM) and fourier transform infrared (FT-IR) were used to characterize the products. At synthesized CuS/MCM-41 sample in ethylene glycol, X-ray diffraction and diffuse reflectance spectroscopy showed pure covellite phase of copper sulfide with high crystality. But prepared CuS/MCM-41 sample in water shows the covellite, chalcocite and the djurleite phase of copper sulfide nanostructures. The formation of CuS nanostructures was confirmed by FT-IR. Photocatalytic activity of CuS/MCM-41 nanocomposites was studied for degradation of Methylene Blue (MB) under visible light. The CuS/MCM-41 nanocomposite is more effective nanocatalyst than synthesized CuS/MCM-41 sample in water for degradation of methylene blue. Several parameters were examined, catalyst amount (0.1-1gL(-1)), pH (1-13) and initial concentration of MB (0.96-10ppm). The extent of degradation was estimated from the residual concentration by spectrophotometrically. The support size was obtained in the range 60-145nm by TEM. In the same way, the average size of copper sulfide in CuSMCM-41E and CuS/MCM-41W nanostructures were obtained about 10nm and 16nm, respectively. Copyright © 2013 Elsevier B.V. All rights reserved.

  5. Low-temperature solid-state synthesis and optical properties of CdS-ZnS and ZnS-CdS alloy nanoparticles

    International Nuclear Information System (INIS)

    Liu Jinsong; Zhao Chuanbao; Li Ziquan; Chen Jiankang; Zhou Hengzhi; Gu Shanqun; Zeng Youhong; Li Yongchan; Huang Yongbing

    2011-01-01

    Highlights: → Using a simple low-temperature solid-state synthetic method, ZnS-CdS and CdS-ZnS alloy nanoparticles were obtained, respectively. → The size of the nanoparticles increased with increasing reaction temperature, and reaction sequence had no effect on the size of the nanoparticles under the same temperature. → The particle diameters of the CdS-ZnS products decreased gradually with increasing Cd 2+ /Zn 2+ molar ratio, whereas those of the ZnS-CdS products increased gradually with increasing Zn 2+ /Cd 2+ molar ratio. → The study shows that sufficient grinding and crystalline water may be a key in forming the alloy nanoparticles. → Optical properties of the products depend on reaction temperature, reactant addition sequence, and reactant molar ratio. - Abstract: A simple low-temperature solid-state synthetic method was employed to obtain ZnS-CdS and CdS-ZnS alloy nanoparticles. The effects of reaction sequence, reactant molar ratios, and synthesis temperature on the products were investigated. The crystal structure and morphology of the products were characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), and fourier transform infrared (FT-IR) spectroscopy. The results show that the products are alloy nanoparticles with a cubic phase structure. The formation mechanism of the alloy nanoparticles is briefly discussed. Sufficient grinding and crystalline water may be essential to form alloy nanoparticles. Ultraviolet-visible (UV-vis) spectra show that the edge absorptions of the CdS-ZnS and ZnS-CdS nanoparticles were located between those of ZnS and CdS bulks, and the absorbance at the peak maximum was practically dependent on reaction temperature, reaction sequence, and molar ratio. Extrinsic deep-level emission resulted in strong peaks in the photoluminescence (PL) spectra. The position and intensity of the emission peaks varied with the conditions during synthesis.

  6. Synthesis and evaluation of nitroxide-based oligoradicals for low-temperature dynamic nuclear polarization in solid state NMR

    Science.gov (United States)

    Yau, Wai-Ming; Thurber, Kent R.; Tycko, Robert

    2014-07-01

    We describe the synthesis of new nitroxide-based biradical, triradical, and tetraradical compounds and the evaluation of their performance as paramagnetic dopants in dynamic nuclear polarization (DNP) experiments in solid state nuclear magnetic resonance (NMR) spectroscopy with magic-angle spinning (MAS). Under our experimental conditions, which include temperatures in the 25-30 K range, a 9.4 T magnetic field, MAS frequencies of 6.2-6.8 kHz, and microwave irradiation at 264.0 GHz from a 800 mW extended interaction oscillator source, the most effective compounds are triradicals that are related to the previously-described compound DOTOPA-TEMPO (see Thurber et al., 2010), but have improved solubility in glycerol/water solvent near neutral pH. Using these compounds at 30 mM total nitroxide concentration, we observe DNP enhancement factors of 92-128 for cross-polarized 13C NMR signals from 15N,13C-labeled melittin in partially protonated glycerol/water, and build-up times of 2.6-3.8 s for 1H spin polarizations. Net sensitivity enhancements with biradical and tetraradical dopants, taking into account absolute 13C NMR signal amplitudes and build-up times, are approximately 2-4 times lower than with the best triradicals.

  7. Low-temperature synthesis and characterization of helical carbon fibers by one-step chemical vapour deposition

    Science.gov (United States)

    Jin, Yongzhong; Chen, Jian; Fu, Qingshan; Li, Binghong; Zhang, Huazhi; Gong, Yong

    2015-01-01

    Helical carbon fibers (HCNFs) were synthesized by one-step chemical vapour deposition using cupric tartrate as a catalyst at temperature below 500 °C. The bound rubber of natural rubber (NR)/HCNFs were also prepared in this study. The results of thermogravimetry-differential scanning calorimetry (TG/DSC) for cupric tartrate nanoparticles show that the transformation of C4H4CuO6 → Cu reaction occurs at ∼250-310 °C. The characterization of scanning electron microscopy (SEM), transmission electron microscope (TEM), X-ray diffraction (XRD) and Raman spectrum for the synthesized products confirms that the synthesis of HCNFs is highly temperature-dependent. The straight fibers with the fiber diameter of 100-400 nm are obtained at 280 °C and HCNFs can be synthesized at higher temperature, with the coil diameter of 0.5-1 μm and fiber diameter of 100-200 nm at 380 °C, and the coil diameter of ∼100 nm and fiber diameter of ∼80 nm at 480 °C. The maximum of the bound-rubber content (37%) can be obtained with the addition of 100 wt.% HCNFs in NR, which indicates that the coiled configuration of HCNFs makes a noticeable contribution to the reinforcement of NR/CB system.

  8. Systematic staging design applied to the fixed-bed reactor series for methanol and one-step methanol/dimethyl ether synthesis

    International Nuclear Information System (INIS)

    Manenti, Flavio; Leon-Garzon, Andres R.; Ravaghi-Ardebili, Zohreh; Pirola, Carlo

    2014-01-01

    This work investigates possible design advances in the series of fixed-bed reactors for methanol and dimethyl ether synthesis. Specifically, the systematic staging design proposed by Hillestad [1] is applied to the water-cooled and gas-cooled series of reactors of Lurgi's technology. The procedure leads to new design and operating conditions with respect to the current best industrial practice, with relevant benefits in terms of process yield, energy saving, and net income. The overall mathematical model for the process simulation and optimization is reported in the work together with dedicated sensitivity analysis studies. - Highlights: • Systematic staging design is applied to methanol and methanol/DME synthesis. • New configurations for the synthesis reactor network are proposed and assessed. • Comparison with the industrial best practice is provided. • Energy-process optimization is performed to improve the overall yield of the process

  9. Synthesis of Li{sub 2}SiO{sub 3} at low temperature; Sintesis de Li{sub 2}SiO{sub 3} a baja temperatura

    Energy Technology Data Exchange (ETDEWEB)

    Mondragon G, G. [ININ, 52750 La Marquesa, Estado de Mexico (Mexico)

    2007-07-01

    The main objective of this work is to develop a new synthesis method to obtain one of the more studied ceramics in this field Li{sub 2}SiO{sub 3}) in a simple and economic way using different solutions (urea and ammonium hydroxide). The particular objectives are first to prepare the Li{sub 2}SiO{sub 3} ceramic, by means of the use of the reaction conventional technique in solid state at temperatures between 800 and 900 C to compare it with the one proposed in this work and this way to observe the advantages that it would gives us the new method. Later on, the same one was synthesized lithium ceramic (Li{sub 2}SiO{sub 3}) by means of the new method at low temperature (between 80 and 90 C), using silicic acid and lithium hydroxide like precursory reagents and different solutions (urea and ammonium hydroxide) for the optimization in their synthesis. Finally, it was carried out the characterization of these materials by means of X-ray diffraction (XRD), electronic microscopes (SEM and TEM), nitrogen physisorption (method BET) and thermal gravimetric analysis (TGA) to observe the differences that exist among the conventional method and the proposed method and by this way to determine the advantages of the last method. (Author)

  10. Synthesis of acetic acid via methanol hydrocarboxylation with CO2 and H2

    OpenAIRE

    Qian, Qingli; Zhang, Jingjing; Cui, Meng; Han, Buxing

    2016-01-01

    Acetic acid is an important bulk chemical that is currently produced via methanol carbonylation using fossil based CO. Synthesis of acetic acid from the renewable and cheap CO2 is of great importance, but state of the art routes encounter difficulties, especially in reaction selectivity and activity. Here we report a route to produce acetic acid from CO2, methanol and H2. The reaction can be efficiently catalysed by Ru?Rh bimetallic catalyst using imidazole as the ligand and LiI as the promot...

  11. In situ synthesis of nanocomposite membranes: comprehensive improvement strategy for direct methanol fuel cells.

    Science.gov (United States)

    Rao, Siyuan; Xiu, Ruijie; Si, Jiangju; Lu, Shanfu; Yang, Meng; Xiang, Yan

    2014-03-01

    In situ synthesis is a powerful approach to control nanoparticle formation and consequently confers extraordinary properties upon composite membranes relative to conventional doping methods. Herein, uniform nanoparticles of cesium hydrogen salts of phosphotungstic acid (CsPW) are controllably synthesized in situ in Nafion to form CsPW–Nafion nanocomposite membranes with both improved proton conductivity and methanol-crossover suppression. A 101.3% increase of maximum power density has been achieved relative to pristine Nafion in a direct methanol fuel cell (DMFC), indicating a potential pathway for large-scale fabrication of DMFC alternative membranes.

  12. Controlled synthesis of graphitic carbon-encapsulated α-Fe2O3 nanocomposite via low-temperature catalytic graphitization of biomass and its lithium storage property

    International Nuclear Information System (INIS)

    Wu, Feng; Huang, Rong; Mu, Daobin; Wu, Borong; Chen, Yongjian

    2016-01-01

    Highlights: • Facile synthesis of graphitic carbon/α-Fe 2 O 3 nano-sized anode composite. • In situ low temperature catalytic graphitization of biomass material. • Onion-like graphitic carbon layers conformally encapsulating around α-Fe 2 O 3 core. • High lithium storage properties, especially, outstanding cycle performance. - Abstract: A delicate structure of graphitic carbon-encapsulated α-Fe 2 O 3 nanocomposite is in situ constructed via “Absorption–Catalytic graphitization–Oxidation” strategy, taking use of biomass matter of degreasing cotton as carbon precursor and solution reservoir. With the assistance of the catalytic graphitization effect of iron core, onion-like graphitic carbon (GC) shell is made directly from the biomass at low temperature (650 °C). The nanosized α-Fe 2 O 3 particles would effectively mitigate volumetric strain and shorten Li + transport path during charge/discharge process. The graphitic carbon shells may promote charge transfer and protect active particles from directly exposing to electrolyte to maintain interfacial stability. As a result, the as-prepared α-Fe 2 O 3 @GC composite displays an outstanding cycle performance with a reversible capacity of 1070 mA h g −1 after 430 cycles at 0.2C, as well as a good rate capability of ∼ 950 mA h g −1 after 100 cycles at 1C and ∼ 850 mA h g −1 even up to 200 cycles at a 2C rate.

  13. Synthesis of acetic acid via methanol hydrocarboxylation with CO2 and H2.

    Science.gov (United States)

    Qian, Qingli; Zhang, Jingjing; Cui, Meng; Han, Buxing

    2016-05-11

    Acetic acid is an important bulk chemical that is currently produced via methanol carbonylation using fossil based CO. Synthesis of acetic acid from the renewable and cheap CO2 is of great importance, but state of the art routes encounter difficulties, especially in reaction selectivity and activity. Here we report a route to produce acetic acid from CO2, methanol and H2. The reaction can be efficiently catalysed by Ru-Rh bimetallic catalyst using imidazole as the ligand and LiI as the promoter in 1,3-dimethyl-2-imidazolidinone (DMI) solvent. It is confirmed that methanol is hydrocarboxylated into acetic acid by CO2 and H2, which accounts for the outstanding reaction results. The reaction mechanism is proposed based on the control experiments. The strategy opens a new way for acetic acid production and CO2 transformation, and represents a significant progress in synthetic chemistry.

  14. Synthesis and Characterization of 1D Ceria Nanomaterials for CO Oxidation and Steam Reforming of Methanol

    Directory of Open Access Journals (Sweden)

    Sujan Chowdhury

    2011-01-01

    Full Text Available Novel one-dimensional (1D ceria nanostructure has been investigated as a promising and practical approach for the reforming of methanol reaction. Size and shape of the ceria nanomaterials are directly involved with the catalytic activities. Several general synthesis routes as including soft and hard template-assemble phenomenon for the preparation of 1D cerium oxide are discussed. This preparation phenomenon is consisting with low cost and ecofriendly. Nanometer-sized 1D structure provides a high-surface area that can interact with methanol and carbon-monoxide reaction. Overall, nanometer-sized structure provides desirable properties, such as easy recovery and regeneration. As a result, the use of 1D cerium has been suitable for catalytic application of reforming. In this paper, we describe the 1D cerium oxide syntheses route and then summarize their properties in the field of CO oxidation and steam reforming of methanol approach.

  15. Preparation and characterization of stable copper/zinc oxide/alumina catalysts for methanol synthesis

    Energy Technology Data Exchange (ETDEWEB)

    Hoeppener, R H; Doesburg, E B; Scholten, J J

    1986-08-15

    A series of Cu/ZnO/Al/sub 2/O/sub 3/ catalysts for the low pressure methanol synthesis has been prepared by coprecipitation with a sodium carbonate solution from solutions of a mixture of the corresponding metal nitrates, followed by drying, calcination and reduction. The catalysts and their precursors were analyzed by techniques like X-ray diffraction, X-ray line broadening, differential thermal analysis, chemical analysis, adsorptive decomposition of N/sub 2/O and B.E.T.-measurements. The catalytic activity for the methanol synthesis was determined in a flow reactor under industrial conditions. Depending on the metal ion ratio in the initial metal nitrate solutions different compounds were formed during coprecipitation, like rosasite, malachite, Cu, Zn-hydrotalcite and a ternary compound which was called roderite. Its structure is unknown and it contains, besides Zn/sup 2+/, up to 28 at% Cu/sup 2+/ and up to 17 at% Al/sup 3+/. Addition of 7 at% Mg/sup 2+/ stabilizes the Cu, Zn-hydrotalcite structure but leads to a drastic decrease in catalytic activity. The rate of methanol production depends on the phase composition of the precursors. Rosasite containing precursors give the highest activity; hydrotalcite proves to be an excellent catalyst stabilizer which evokes the formation of small Cu and ZnO particles. Mg/sup 2+/ inhibits methanol production. 6 figs., 1 tab., 18 refs.

  16. Gasoline from Wood via Integrated Gasification, Synthesis, and Methanol-to-Gasoline Technologies

    Energy Technology Data Exchange (ETDEWEB)

    Phillips, S. D.; Tarud, J. K.; Biddy, M. J.; Dutta, A.

    2011-01-01

    This report documents the National Renewable Energy Laboratory's (NREL's) assessment of the feasibility of making gasoline via the methanol-to-gasoline route using syngas from a 2,000 dry metric tonne/day (2,205 U.S. ton/day) biomass-fed facility. A new technoeconomic model was developed in Aspen Plus for this study, based on the model developed for NREL's thermochemical ethanol design report (Phillips et al. 2007). The necessary process changes were incorporated into a biomass-to-gasoline model using a methanol synthesis operation followed by conversion, upgrading, and finishing to gasoline. Using a methodology similar to that used in previous NREL design reports and a feedstock cost of $50.70/dry ton ($55.89/dry metric tonne), the estimated plant gate price is $16.60/MMBtu ($15.73/GJ) (U.S. $2007) for gasoline and liquefied petroleum gas (LPG) produced from biomass via gasification of wood, methanol synthesis, and the methanol-to-gasoline process. The corresponding unit prices for gasoline and LPG are $1.95/gallon ($0.52/liter) and $1.53/gallon ($0.40/liter) with yields of 55.1 and 9.3 gallons per U.S. ton of dry biomass (229.9 and 38.8 liters per metric tonne of dry biomass), respectively.

  17. Synthesis of biodiesel from soybean oil by coupling catalysis with subcritical methanol

    International Nuclear Information System (INIS)

    Yin Jianzhong; Xiao Min; Wang Aiqin; Xiu Zhilong

    2008-01-01

    Biodiesel synthesis from soybean oil and methanol was investigated under supercritical and subcritical conditions. Under the supercritical conditions, the maximum methyl ester yield exceeded 98% when the molar ratio of methanol to oil was 42:1 and the reaction temperature ranged from 260 deg. C to 350 deg. C. In order to decrease the operational temperature and pressures and to increase the conversion efficiency of methanol, first co-solvent was added to the reaction mixture to improve the reaction process, and then a novel idea was presented in which catalysis and supercritical effect were coupled together. Thus, with 2.5 wt% hexane, temperature of 300 deg. C, methanol to oil ratio of 42, a 85.5% conversion is observed in 30 min, while a 62.2% conversion is observed without hexane in the same condition; with less carbon dioxide, temperature of 300 deg. C, methanol to oil ratio of 42, a 91.6% conversion is observed in 20 min, while a 51.4% conversion is observed without carbon dioxide in the same condition; With only a little amount of potassium hydroxide as the catalyst (KOH/oil = 0.1 wt%), a 98% yield of methyl esters was obtained in 10 min at a reaction temperature of 160 deg. C and the molar ratio (methanol/oil) of 24:1. In contrast, above 1 wt% of catalyst is required in the conventional alkali-catalyzed method; while only 6% yield of methyl ester was obtained at 260 deg. C (corresponding to subcritical conditions) without the catalyst. This result demonstrated that by coupling the catalysis and subcritical operation, the amount of catalyst could be largely reduced and the methanol utilization could be significantly enhanced. Thus, the present method offers some advantages over both the conventional alkali-catalyst method and the expensive supercritical method

  18. Low temperature synthesis of {tau}-zirconium hydrogenophosphate [{tau}-Zr(HPO{sub 4}){sub 2}] and a new sodic form obtained by ion exchange

    Energy Technology Data Exchange (ETDEWEB)

    Fernandez-Valverde, Suilma M., E-mail: suilma.fernandez@inin.gob.mx [Depto. de Quimica, Instituto Nacional de Investigaciones Nucleares, A.P. 18-1027, Mexico D.F. C.P. 11801 (Mexico); Contreras-Ramirez, Aida [Depto. de Quimica, Instituto Nacional de Investigaciones Nucleares, A.P. 18-1027, Mexico D.F. C.P. 11801 (Mexico); Depto. de Tecnologia de Materiales, Instituto Nacional de Investigaciones Nucleares, A.P. 18-1027, Mexico D.F. C.P. 11801 (Mexico); Facultad de Ciencias, Universidad Autonoma del Estado de Mexico, Piedras Blancas El Cerrillo, Tlachaloya Estado de Mexico, CP.5000 (Mexico); Ordonez-Regil, Eduardo [Depto. de Quimica, Instituto Nacional de Investigaciones Nucleares, A.P. 18-1027, Mexico D.F. C.P. 11801 (Mexico); Fernandez-Garcia, M. Eufemia [Depto. de Tecnologia de Materiales, Instituto Nacional de Investigaciones Nucleares, A.P. 18-1027, Mexico D.F. C.P. 11801 (Mexico); Perez-Alvarez, Mario [Depto. de Ambientales, Instituto Nacional de Investigaciones Nucleares, A.P. 18-1027, Mexico D.F. C.P. 11801 (Mexico)

    2013-02-15

    A new method for the synthesis of 3-D {tau}-zirconium hydrogenophosphate (TZP) was developed using solid-state reactions at low temperature and atmospheric pressure in a nitrogen atmosphere in a two-hour reaction time. The characterization of the compound was performed using X-ray diffraction, infrared spectroscopy, scanning electron microscopy, energy dispersive X-ray spectroscopy, differential scanning calorimetric, thermochemical analysis and X-ray photoelectron spectroscopy. A sodic form of the compound obtained by the immersion of TZP in a sodium hydroxide solution was characterized using the same techniques along with neutron activation analysis. The XPS spectra confirm the binding energy value for sodium-oxygen, and the XRD diffraction reveals the formation of a new sodium compound. - Graphical abstract: DRX, XPS and MEB of {tau}-zirconium hydrogenophosphate and its sodic form on the surface of TZP. Highlights: Black-Right-Pointing-Pointer New method for the syntheses of 3-D {tau}-zirconium hydrogenophosphate (TZP). Black-Right-Pointing-Pointer A sodic form of the TZP was obtained by the immersion of TZP in a sodium hydroxide. Black-Right-Pointing-Pointer The sodium compound is only formed on the TZP surface.

  19. One-step and low-temperature synthesis of iodine-doped graphene and its multifunctional applications for hydrogen evolution reaction and electrochemical sensing

    International Nuclear Information System (INIS)

    Chu, Ke; Wang, Fan; Zhao, Xiao-lin; Wei, Xiao-ping; Wang, Xin-wei; Tian, Ye

    2017-01-01

    Iodine (I) has emerged as a powerful heteroatom dopant for efficiently tailoring the electrocatalytic properties of graphene. However, the preparation methods of I-doped graphene (I-G) and its electrocatalysis applications remain largely unexplored. Herein, a one-step and low-temperature hydrothermal approach was developed for the successful synthesis of I-G with a high I-doping level (0.52 at.%). The resulting I-G was then applied as a metal-free catalyst for hydrogen evolution reaction (HER) and electrochemical sensing. It was shown that the I-G exhibited a dramatically enhanced HER activity compared to undoped graphene, attributed to the critical role of I-doping in offering large exposed active sites and high electron transfer capability. Furthermore, I-G also displayed attractive sensing performances for highly sensitive and selective detection of dopamine. These findings demonstrate that the hydrothermally synthesized I-G can be a promising electrocatalyst for multifunctional applications in water-splitting and electrochemical sensing.

  20. Effect of precursor solutions stirring on deep level defects concentration and spatial distribution in low temperature aqueous chemical synthesis of zinc oxide nanorods

    Energy Technology Data Exchange (ETDEWEB)

    Alnoor, Hatim, E-mail: hatim.alnoor@liu.se; Chey, Chan Oeurn; Pozina, Galia; Willander, Magnus; Nur, Omer [Department of Science and Technology (ITN), Campus Norrköping, Linköping University, SE-601 74 Norrköping (Sweden); Liu, Xianjie; Khranovskyy, Volodymyr [Department of Physics, Chemistry and Biology (IFM), Linköping University, SE-583 81 Linköping (Sweden)

    2015-08-15

    Hexagonal c-axis oriented zinc oxide (ZnO) nanorods (NRs) with 120-300 nm diameters are synthesized via the low temperature aqueous chemical route at 80 °C on silver-coated glass substrates. The influence of varying the precursor solutions stirring durations on the concentration and spatial distributions of deep level defects in ZnO NRs is investigated. Room temperature micro-photoluminesnce (μ-PL) spectra were collected for all samples. Cathodoluminescence (CL) spectra of the as-synthesized NRs reveal a significant change in the intensity ratio of the near band edge emission (NBE) to the deep-level emission (DLE) peaks with increasing stirring durations. This is attributed to the variation in the concentration of the oxygen-deficiency with increasing stirring durations as suggested from the X-ray photoelectron spectroscopy analysis. Spatially resolved CL spectra taken along individual NRs revealed that stirring the precursor solutions for relatively short duration (1-3 h), which likely induced high super saturation under thermodynamic equilibrium during the synthesis process, is observed to favor the formation of point defects moving towards the tip of the NRs. In contrary, stirring for longer duration (5-15 h) will induce low super saturation favoring the formation of point defects located at the bottom of the NRs. These findings demonstrate that it is possible to control the concentration and spatial distribution of deep level defects in ZnO NRs by varying the stirring durations of the precursor solutions.

  1. Dry reforming of coke oven gases over activated carbon to produce syngas for methanol synthesis

    Energy Technology Data Exchange (ETDEWEB)

    J.M. Bermudez; B. Fidalgo; A. Arenillas; J.A. Menendez [Instituto Nacional del Carbn, Oviedo (Spain)

    2010-10-15

    The dry reforming of coke oven gases (COG) over an activated carbon used as catalyst has been studied in order to produce a syngas suitable for methanol synthesis. The primary aim of this work was to study the influence of the high amount of hydrogen present in the COG on the process of dry reforming, as well as the influence of other operation conditions, such us temperature and volumetric hourly space velocity (VHSV). It was found that the reverse water gas shift (RWGS) reaction takes place due to the hydrogen present in the COG, and that its influence on the process increases as the temperature decreases. This situation may give rise to the consumption of the hydrogen present in the COG, and the consequent formation of a syngas which is inappropriate for the synthesis of methanol. This reaction can be avoided by working at high temperatures (about 1000{sup o}C) in order to produce a syngas that is suitable for methanol synthesis. It was also found that the RWGS reaction is favoured by an increase in the VHSV. In addition, the active carbon FY5 was proven to be an adequate catalyst for the production of syngas from COG. 25 refs., 7 figs., 2 tabs.

  2. Process for obtaining methanol. Verfahren zur Gewinnung von Methanol

    Energy Technology Data Exchange (ETDEWEB)

    Link, H; Watson, A

    1983-12-08

    Synthetic gas is generated and converted to methanol in a reactor. After the separation of the crude methanol, there is a multi-stage methanol distillation. Condensate occurring during distillation is at least partly fed back before the methanol synthesis.

  3. WORKSHOP: Low temperature devices

    International Nuclear Information System (INIS)

    Anon.

    1987-01-01

    With extraterrestrial neutrinos (whether from the sun or further afield) continuing to make science news, and with the search for the so far invisible 'dark matter' of the universe a continual preoccupation, physicists from different walks of life (solid state, low temperature, particles, astrophysics) gathered at a workshop on low temperature devices for the detection of neutrinos and dark matter, held from 12-13 March at Ringberg Castle on Lake Tegernsee in the Bavarian Alps, and organized by the Max Planck Institute for Physics and Astrophysics in Munich

  4. WORKSHOP: Low temperature devices

    Energy Technology Data Exchange (ETDEWEB)

    Anon.

    1987-06-15

    With extraterrestrial neutrinos (whether from the sun or further afield) continuing to make science news, and with the search for the so far invisible 'dark matter' of the universe a continual preoccupation, physicists from different walks of life (solid state, low temperature, particles, astrophysics) gathered at a workshop on low temperature devices for the detection of neutrinos and dark matter, held from 12-13 March at Ringberg Castle on Lake Tegernsee in the Bavarian Alps, and organized by the Max Planck Institute for Physics and Astrophysics in Munich.

  5. Effect of precursor solutions stirring on deep level defects concentration and spatial distribution in low temperature aqueous chemical synthesis of zinc oxide nanorods

    Directory of Open Access Journals (Sweden)

    Hatim Alnoor

    2015-08-01

    Full Text Available Hexagonal c-axis oriented zinc oxide (ZnO nanorods (NRs with 120-300 nm diameters are synthesized via the low temperature aqueous chemical route at 80 °C on silver-coated glass substrates. The influence of varying the precursor solutions stirring durations on the concentration and spatial distributions of deep level defects in ZnO NRs is investigated. Room temperature micro-photoluminesnce (μ-PL spectra were collected for all samples. Cathodoluminescence (CL spectra of the as-synthesized NRs reveal a significant change in the intensity ratio of the near band edge emission (NBE to the deep-level emission (DLE peaks with increasing stirring durations. This is attributed to the variation in the concentration of the oxygen-deficiency with increasing stirring durations as suggested from the X-ray photoelectron spectroscopy analysis. Spatially resolved CL spectra taken along individual NRs revealed that stirring the precursor solutions for relatively short duration (1-3 h, which likely induced high super saturation under thermodynamic equilibrium during the synthesis process, is observed to favor the formation of point defects moving towards the tip of the NRs. In contrary, stirring for longer duration (5-15 h will induce low super saturation favoring the formation of point defects located at the bottom of the NRs. These findings demonstrate that it is possible to control the concentration and spatial distribution of deep level defects in ZnO NRs by varying the stirring durations of the precursor solutions.

  6. Microwave assisted low temperature synthesis of sodium zirconium phosphate (NZP) and the leachability of some selected fission products incorporated in its structure

    International Nuclear Information System (INIS)

    Dharwadkar, S.R.

    2008-01-01

    Full text: Microwave assisted procedure for low temperature solid state synthesis of sodium zirconium phosphate (NZP), a material with the potential for immobilization and disposal of high level nuclear waste, was developed. Four selected fission products, namely cesium, strontium, tellurium and ruthenium were introduced (substituted) in the NZP matrix during its synthesis at 450 deg C. More than 85% of these elements incorporated at this temperature could be retained in the NZP compacts, sintered in air at 1000 deg C to nearly 90% of the theoretical density of pure sodium zirconium phosphate. Leaching studies were carried out on the fission product substituted sintered NZP compacts in pure de-ionized water and 80% saturated brine solution at the ambient temperatures of 30 deg C and 90 deg C for four weeks. The major part of leaching in all the cases was observed in the first week. The maximum amount of the substituted element leached in the liquid media after four weeks, however did not exceed 12% of the total amount originally present in the sample before leaching. No significant leaching was observed for any of the dopant elements after four weeks. Among the substituted elements maximum leaching was observed for tellurium followed by cesium and strontium. Ruthenium showed virtually no leaching under the conditions employed. Leaching was found to decrease considerably in multiple element substituted NZP. The effect of temperature on the leaching rate was marginal but substantial difference was observed when the leachant was changed from pure de-ionized water to brine solution. Tellurium and strontium exhibited three and two fold decrease in the leaching rate respectively on changing the leachant from pure de-ionized water to 80% saturated brine solution. The leach rate of Cs however remained virtually unaffected by this change. The SEM and EDX analysis of the surfaces of the leached pellets showed virtual absence of the dopants introduced in the NZP matrix

  7. Synthesis, characterization and catalytic activity toward methanol oxidation of electrocatalyst Pt4+-NH2-MCM-41

    International Nuclear Information System (INIS)

    Zheng Huajun; Chen Zuo; Wang Limin; Ma Chun’an

    2012-01-01

    Highlights: ► It was first confirmed that the Pt 4+ exhibited a good electro-catalytic property for methanol oxidation. ► The Pt 4+ 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 Pt 4+ and large specific surface area. - Abstract: Mesoporous material with functional group (Pt 4+ -NH 2 -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 N 2 adsorption–desorption measurement pointed out that Pt was adsorbed on the NH 2 -MCM-41 surface as the oxidation state (Pt 4+ ) and the surface area of Pt 4+ -NH 2 -MCM-41 was up to 564 m 2 /g. Transmission electron microscopy and elemental mapping indicated a homogeneous distribution of Pt 4+ throughout all surface of the mesoporous materials. Electro-catalytic properties of methanol oxidation on the Pt 4+ -NH 2 -MCM-41 electrode were investigated with electrochemical methods. The results showed that the Pt 4+ -NH 2 -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.

  8. Low temperatures - hot topic

    Energy Technology Data Exchange (ETDEWEB)

    Anon.

    1988-09-15

    Neutrino mass measurements, next-generation double beta experiments, solar neutrino detection, searches for magnetic monopoles and the challenge of discovering what most of the Universe is made of (dark matter), not to mention axions (cosmic and solar), supersymmetric neutral particles and cosmic neutrinos. All this physics could use cryogenic techniques. Thus the second European Workshop on Low Temperature Devices for the Detection of Low Energy Neutrinos and Dark Matter, held at LAPP (Annecy) in May, covered an active and promising field.

  9. Low temperatures - hot topic

    International Nuclear Information System (INIS)

    Anon.

    1988-01-01

    Neutrino mass measurements, next-generation double beta experiments, solar neutrino detection, searches for magnetic monopoles and the challenge of discovering what most of the Universe is made of (dark matter), not to mention axions (cosmic and solar), supersymmetric neutral particles and cosmic neutrinos. All this physics could use cryogenic techniques. Thus the second European Workshop on Low Temperature Devices for the Detection of Low Energy Neutrinos and Dark Matter, held at LAPP (Annecy) in May, covered an active and promising field

  10. Low temperature carbonization

    Energy Technology Data Exchange (ETDEWEB)

    Abbott, A A

    1934-01-10

    A process is described in which coal is passed through a distillation chamber in one retort at a comparatively low temperature, then passing the coal through a distillation chamber of a second retort subjected to a higher temperature, thence passing the coal through the distillation chamber of a third retort at a still higher temperature and separately collecting the liquid and vapors produced from each retort.

  11. Sweating at low temperature

    International Nuclear Information System (INIS)

    Chalaye, H.; Launay, J.P.

    1980-11-01

    Tests of penetration liquids normally used between 10 and 40 0 C have shown that the arrangement of operationaal conditions (penetration and revealing times) was not sufficient to maintain their sensitivity below 10 0 C, thereby confirming that this temperature is a limit below which such products cannot be employed. The results achieved with a penetrant and a tracer specially devised for low temperatures (SHERWIN B 305 + D100) are satisfactory between 0 0 C and 15 0 C [fr

  12. Cobalt catalysts for the conversion of methanol and for Fischer-tropsch synthesis to produce hydrocarbons

    International Nuclear Information System (INIS)

    Mauldin, C.H.; Davis, S.M.; Arcuri, K.B.

    1987-01-01

    A regeneration stable catalyst is described for the conversion at reaction conditions of methanol or synthesis gas to liquid hydrocarbons which consists essentially of from about 2 percent to about 25 percent cobalt, based on the weight of the catalyst composition, composited with titania, or a titania-containing support, to which is added sufficient of a zirconium, hafnium, cerium, or uranium promoter to provide a weight ratio of the zirconium, hafnium, cerium, or uranium metal:cobalt greater than about 0.101:1

  13. Quantification of zinc atoms in a surface alloy on copper in an industrial-type methanol synthesis catalyst

    DEFF Research Database (Denmark)

    Kuld, Sebastian; Moses, Poul Georg; Sehested, Jens

    2014-01-01

    Methanol has recently attracted renewed interest because of its potential importance as a solar fuel. Methanol is also an important bulk chemical that is most efficiently formed over the industrial Cu/ZnO/Al2O3 catalyst. The identity of the active site and, in particular, the role of ZnO as a pro......Methanol has recently attracted renewed interest because of its potential importance as a solar fuel. Methanol is also an important bulk chemical that is most efficiently formed over the industrial Cu/ZnO/Al2O3 catalyst. The identity of the active site and, in particular, the role of Zn......O as a promoter for this type of catalyst is still under intense debate. Structural changes that are strongly dependent on the pretreatment method have now been observed for an industrial-type methanol synthesis catalyst. A combination of chemisorption, reaction, and spectroscopic techniques provides a consistent...

  14. Rapid synthesis and characterization of hybrid ZnO@Au core–shell nanorods for high performance, low temperature NO{sub 2} gas sensor applications

    Energy Technology Data Exchange (ETDEWEB)

    Ponnuvelu, Dinesh Veeran [Nanosensor Laboratory, PSG Institute of Advanced Studies, Coimbatore 641 004 (India); Pullithadathil, Biji, E-mail: bijuja123@yahoo.co.in [Nanosensor Laboratory, PSG Institute of Advanced Studies, Coimbatore 641 004 (India); Prasad, Arun K.; Dhara, Sandip [Surface and Nanoscience Division, Indira Gandhi Center for Atomic Research, Kalpakkam (India); Ashok, Anuradha [Nanosensor Laboratory, PSG Institute of Advanced Studies, Coimbatore 641 004 (India); Mohamed, Kamruddin; Tyagi, Ashok Kumar [Surface and Nanoscience Division, Indira Gandhi Center for Atomic Research, Kalpakkam (India); Raj, Baldev [Nanosensor Laboratory, PSG Institute of Advanced Studies, Coimbatore 641 004 (India)

    2015-11-15

    Graphical abstract: - Highlights: • Hybrid ZnO@Au core–shell nanorods were developed using rapid chemical method that can be used as a high performance, low temperature NO{sub 2} gas sensor. • Surface defect analysis (PL and XPS) clearly illustrates the presence of surface oxygen species and Zn interstitials involved in charge transport properties in-turn affecting gas sensing properties. • Hybrid ZnO@Au core–shell nanorods establish enhanced gas sensing performance at 150 °C compared to ZnO (300 °C) with a lower detection limit of 500 ppb using conventional electrodes. • The enhanced performance of ZnO@Au core–shell nanorods based sensor was owing to the presence of Au nanoclusters on the surface of ZnO nanorods which is attributed to the formation of Schottky contacts at the interfaces leading to sensitization effects. • The hybrid material found to be selective toward NO{sub 2} gas and highly stable in nature. - Abstract: A rapid synthesis route for hybrid ZnO@Au core–shell nanorods has been realized for ultrasensitive, trace-level NO{sub 2} gas sensor applications. ZnO nanorods and hybrid ZnO@Au core–shell nanorods are structurally analyzed using X-ray diffraction (XRD), high resolution transmission electron microscopy (HR-TEM) and X-ray photoelectron spectroscopy (XPS). Optical characterization using UV–visible (UV–vis), photoluminescence (PL) and Raman spectroscopies elucidate alteration in the percentage of defect and charge transport properties of ZnO@Au core–shell nanorods. The study reveals the accumulation of electrons at metal–semiconductor junctions leading to upward band bending for ZnO and thus favors direct electron transfer from ZnO to Au nanoclusters, which mitigates charge carrier recombination process. The operating temperature of ZnO@Au core–shell nanorods based sensor significantly decreased to 150 °C compared to alternate NO{sub 2} sensors (300 °C). Moreover, a linear sensor response in the range of 0.5–5

  15. Biodiesel synthesis by direct transesterification of microalga Botryococcus braunii with continuous methanol reflux.

    Science.gov (United States)

    Hidalgo, Pamela; Ciudad, Gustavo; Schober, Sigurd; Mittelbach, Martin; Navia, Rodrigo

    2015-04-01

    Direct transesterification of Botryococcus braunii with continuous acyl acceptor reflux was evaluated. This method combines in one step lipid extraction and esterification/transesterification. Fatty acid methyl esters (FAME) synthesis by direct conversion of microalgal biomass was carried out using sulfuric acid as catalyst and methanol as acyl acceptor. In this system, once lipids are extracted, they are contacted with the catalyst and methanol reaching 82%wt of FAME yield. To optimize the reaction conditions, a factorial design using surface response methodology was applied. The effects of catalyst concentration and co-solvent concentration were studied. Hexane was used as co-solvent for increasing lipid extraction performance. The incorporation of hexane in the reaction provoked an increase in FAME yield from 82% (pure methanol) to 95% when a 47%v/v of hexane was incorporated in the reaction. However, the selectivity towards non-saponifiable lipids such as sterols was increased, negatively affecting biodiesel quality. Copyright © 2015 Elsevier Ltd. All rights reserved.

  16. Low-temperature, high yield synthesis, and convenient isolation of the high-electron-density cluster compound Ta6Br14.8H2O for use in biomacromolecular crystallographic phase determination.

    Science.gov (United States)

    Hay, Daniel N T; Messerle, Louis

    2002-09-01

    Reduction of TaBr(5) with Ga in the presence of KBr in a sealed borosilicate ampule at 400 degrees, followed by aqueous Soxhlet extraction and addition of stannous bromide and hydrobromic acid to the extract, yielded Ta(6)Br(14).8H(2)O in 80-84% yield. The new procedure provides a convenient, low temperature, high yield route to the synthesis of the title compound from inexpensive precursors.

  17. Low temperature destructive distillation

    Energy Technology Data Exchange (ETDEWEB)

    1938-07-05

    A process is given and apparatus is described for the destructive distillation at low temperature of coal, oil shale, and the like by subjection to the action of a stream of hot gases or superhearted steam, flowing in a closed circuit. Subsequent treatment of the distillation residues with a gas stream containing oxygen results in combustion of the carbon-containing material therein brings to a high temperature the solid residue, in which the process comprises subsequently contacting the hot solid residue with the fluid stream effecting the distillation.

  18. Low temperature distillation

    Energy Technology Data Exchange (ETDEWEB)

    Vandegrift, J N; Postel, C

    1929-04-09

    To recover gas, oil tars, and coked residues by low temperature distillation from bituminous coals, lignites, oil shales, and the like, the raw material is fed from a hopper into a rotary retort which is zonally heated, the temperature being greatest at the discharge end. The material is heated first to a relatively low temperature, thereby removing the moisture and lighter volatiles which are withdrawn through a pipe by the suction of a pump, while the higher boiling point volatiles and fixed gases are withdrawn by suction through an outlet from the higher temperature zone. The vapors withdrawn from the opposite ends of the retort pass through separate vapor lines and condensers, and the suction in each end of the retort, caused by the pumps, is controlled by valves, which also control the location of the neutral point in the retort formed by said suction. Air and inert gas may be introduced into the retort from pipe and stack respectively through a pipe, and steam may be admitted into the high temperature zone through a pipe.

  19. Low-temperature carbonization

    Energy Technology Data Exchange (ETDEWEB)

    Strankmuller, J

    1954-01-01

    The low-temperature carbonization plant at Boehlen in Eastern Germany (the first in which Lurgi type ovens were installed) worked with a throughput of 300 tons of brown-coal briquets per day per oven since 1936, later increased to 365 tons per day. The rising demand for low-temperature tar for hydrogenation purposes led to development of a modified oven of 450 tons throughput. This was achieved by stepping up the flow of the circulating gas and air mixture from 420,000 to 560,000 cubic feet per hour and by additional rows of V-shaped deflectors across the width of the oven chamber, which break up and loosen the charge, thus reducing cooling-gas pressure and allowing a greater flow of scavenging gas. The distance traversed by each briquet is nearly doubled, and the temperature gradient is less. It is claimed that the tar and the coke from modified ovens are of comparable quality. The compressive strength of the briquets was found to have an appreciable effect on the output. Better qts the chemistry, mechanism and thermodynamics of the Fischer-Tropsch reaction and aectromagnetic radiation.

  20. 1995 world methanol conference

    International Nuclear Information System (INIS)

    Anon.

    1995-01-01

    The 20 papers contained in this volume deal with the global markets for methanol, the production of MTBE, integrating methanol production into a coal-to-SNG complex, production of methanol from natural gas, catalysts for methanol production from various synthesis gases, combined cycle power plants using methanol as fuel, and economics of the methanol industry. All papers have been processed for inclusion on the data base

  1. Methanol synthesis using captured CO2 as raw material: Techno-economic and environmental assessment

    International Nuclear Information System (INIS)

    Pérez-Fortes, Mar; Schöneberger, Jan C.; Boulamanti, Aikaterini; Tzimas, Evangelos

    2016-01-01

    Highlights: • A carbon utilisation plant that synthesise methanol is simulated in CHEMCAD. • The total amount of CO 2 demand is 1.46 t/t methanol . • The CO 2 not-produced compared to a conventional plant is 0.54 t/t methanol . • Production costs results too high for a financially attractive project. • There is a net potential for CO 2 emissions reduction of 2.71 MtCO 2 /yr in Europe. - Abstract: The purpose of this paper is to assess via techno-economic and environmental metrics the production of methanol (MeOH) using H 2 and captured CO 2 as raw materials. It evaluates the potential of this type of carbon capture and utilisation (CCU) plant on (i) the net reduction of CO 2 emissions and (ii) the cost of production, in comparison with the conventional synthesis process of MeOH Europe. Process flow modelling is used to estimate the operational performance and the total purchased equipment cost; the flowsheet is implemented in CHEMCAD, and the obtained mass and energy flows are utilised as input to calculate the selected key performance indicators (KPIs). CO 2 -based metrics are used to assess the environmental impact. The evaluated MeOH plant produces 440 ktMeOH/yr, and its configuration is the result of a heat integration process. Its specific capital cost is lower than for conventional plants. However, raw materials prices, i.e. H 2 and captured CO 2 , do not allow such a project to be financially viable. In order to make the CCU plant financially attractive, the price of MeOH should increase in a factor of almost 2, or H 2 costs should decrease almost 2.5 times, or CO 2 should have a value of around 222 €/t, under the assumptions of this work. The MeOH CCU-plant studied can utilise about 21.5% of the CO 2 emissions of a pulverised coal (PC) power plant that produces 550 MW net of electricity. The net CO 2 emissions savings represent 8% of the emissions of the PC plant (mainly due to the avoidance of consuming fossil fuels as in the conventional Me

  2. Al2O3 - TiO2-A simple sol-gel strategy to the synthesis of low temperature sintered alumina-aluminium titanate composites through a core-shell approach

    International Nuclear Information System (INIS)

    Jayasankar, M.; Ananthakumar, S.; Mukundan, P.; Wunderlich, W.; Warrier, K.G.K.

    2008-01-01

    A simple sol-gel based core-shell approach for the synthesis of alumina-aluminium titanate composite is reported. Alumina is the core and titania is the shell. The coating of titania has been performed in aqueous medium on alumina particle by means of heterocoagulation of titanyl chloride. Further heat treatment results in low temperature formation of aluminium titanate as well as low temperature sintering of alumina-aluminium titanate composites. The lowering of the reaction temperature can be attributed to the maximisation of the contact surface between the reactants due to the core-shell approach involving nanoparticles. The mechanism of formation of aluminium titanate and the observations on densification features in the present process are compared with that of mixture of oxides under identical conditions. The sintered alumina-aluminium titanate composite has an average grain size of 2 μm. - Graphical abstract: The article presents a simple sol-gel process through core-shell approach to the synthesis of low temperature sintered alumina-aluminium titanate. The lowering of the reaction temperature can be attributed to the maximisation of the contact surface between the reactant due to the core-shell approach. This material showed the better microstructure control compared to the standard solid-state mixing route

  3. Microwave-Assisted Synthesis of Co3(PO42 Nanospheres for Electrocatalytic Oxidation of Methanol in Alkaline Media

    Directory of Open Access Journals (Sweden)

    Prabhakarn Arunachalam

    2017-04-01

    Full Text Available Low-cost and high-performance advanced electrocatalysts for direct methanol fuel cells are of key significance for the improvement of environmentally-pleasant energy technologies. Herein, we report the facile synthesis of cobalt phosphate (Co3(PO42 nanospheres by a microwave-assisted process and utilized as an electrocatalyst for methanol oxidation. The phase formation, morphological surface structure, elemental composition, and textural properties of the synthesized (Co3(PO42 nanospheres have been examined by powder X-ray diffraction (XRD, Fourier transform-infrared spectroscopy (FT-IR, field emission-scanning electron microscopy (FE-SEM, high-resolution transmission electron microscopy (HRTEM, X-ray photoelectron spectroscopy (XPS, and nitrogen adsorption-desorption isotherm investigations. The performance of an electrocatalytic oxidation of methanol over a Co3(PO42 nanosphere-modified electrode was evaluated in an alkaline solution using cyclic voltammetry (CV and chronopotentiometry (CP techniques. Detailed studies were made for the methanol oxidation by varying the experimental parameters, such as catalyst loading, methanol concentration, and long-term stability for the electro-oxidation of methanol. The good electrocatalytic performances of Co3(PO42 should be related to its good surface morphological structure and high number of active surface sites. The present investigation illustrates the promising application of Co3(PO42 nanospheres as a low-cost and more abundant electrocatalyst for direct methanol fuel cells.

  4. Facile synthesis of PbTiO3 truncated octahedra via solid-state reaction and their application in low-temperature CO oxidation by loading Pt nanoparticles

    KAUST Repository

    Yin, Simin; Zhu, Yihan; Ren, Zhaohui; Chao, Chunying; Li, Xiang; Wei, Xiao; Shen, Ge; Han, Yu; Han, Gaorong

    2014-01-01

    Perovskite PbTiO3 (PTO) nanocrystals with a truncated octahedral morphology have been prepared by a facile solid-state reaction. Pt nanoparticles preferentially nucleated on the {111} facet of PTO nanocrystals exhibit a remarkable low-temperature catalytic activity towards CO oxidation from a temperature as low as 30 °C and achieve 100% conversion at ∼50 °C. © 2014 the Partner Organisations.

  5. Microwave-irradiation polyol synthesis of PVP-protected Pt–Ni electrocatalysts for methanol oxidation reaction

    CSIR Research Space (South Africa)

    Mathe, Ntombizodwa R

    2017-01-01

    Full Text Available ://doi.org/10.1007/s12678-017-0441-3 Microwave-Irradiation Polyol Synthesis of PVP-Protected Pt–Ni Electrocatalysts for Methanol Oxidation Reaction Ntombizodwa R. Mathe Manfred R. Scriba Rirhandzu S. Rikhotso Neil J. Coville ABSTRACT: Bimetallic Pt...

  6. Techno-economic assessment of integrating methanol or Fischer-Tropsch synthesis in a South African sugar mill.

    Science.gov (United States)

    Petersen, Abdul M; Farzad, Somayeh; Görgens, Johann F

    2015-05-01

    This study considered an average-sized sugar mill in South Africa that crushes 300 wet tonnes per hour of cane, as a host for integrating methanol and Fischer-Tropsch synthesis, through gasification of a combined flow of sugarcane trash and bagasse. Initially, it was shown that the conversion of biomass to syngas is preferably done by catalytic allothermal gasification instead of catalytic autothermal gasification. Thereafter, conventional and advanced synthesis routes for both Methanol and Fischer-Tropsch products were simulated with Aspen Plus® software and compared by technical and economic feasibility. Advanced FT synthesis satisfied the overall energy demands, but was not economically viable for a private investment. Advanced methanol synthesis is also not viable for private investment since the internal rate of return was 21.1%, because it could not provide the steam that the sugar mill required. The conventional synthesis routes had less viability than the corresponding advanced synthesis routes. Copyright © 2015 Elsevier Ltd. All rights reserved.

  7. Low Temperature Plasma Medicine

    Science.gov (United States)

    Graves, David

    2013-10-01

    Ionized gas plasmas near room temperature are used in a remarkable number of technological applications mainly because they are extraordinarily efficient at exploiting electrical power for useful chemical and material transformations near room temperature. In this tutorial address, I will focus on the newest area of low temperature ionized gas plasmas (LTP), in this case operating under atmospheric pressure conditions, in which the temperature-sensitive material is living tissue. LTP research directed towards biomedical applications such as sterilization, surgery, wound healing and anti-cancer therapy has seen remarkable growth in the last 3-5 years, but the mechanisms responsible for the biomedical effects have remained mysterious. It is known that LTP readily create reactive oxygen species (ROS) and reactive nitrogen species (RNS). ROS and RNS (or RONS), in addition to a suite of other radical and non-radical reactive species, are essential actors in an important sub-field of aerobic biology termed ``redox'' (or oxidation-reduction) biology. I will review the evidence suggesting that RONS generated by plasmas are responsible for their observed therapeutic effects. Other possible bio-active mechanisms include electric fields, charges and photons. It is common in LTP applications that synergies between different mechanisms can play a role and I will review the evidence for synergies in plasma biomedicine. Finally, I will address the challenges and opportunities for plasma physicists to enter this novel, multidisciplinary field.

  8. Low-Temperature Supercapacitors

    Science.gov (United States)

    Brandon, Erik J.; West, William C.; Smart, Marshall C.

    2008-01-01

    An effort to extend the low-temperature operational limit of supercapacitors is currently underway. At present, commercially available non-aqueous supercapacitors are rated for a minimum operating temperature of -40 C. A capability to operate at lower temperatures would be desirable for delivering power to systems that must operate in outer space or in the Polar Regions on Earth. Supercapacitors (also known as double-layer or electrochemical capacitors) offer a high power density (>1,000 W/kg) and moderate energy density (about 5 to 10 Wh/kg) technology for storing energy and delivering power. This combination of properties enables delivery of large currents for pulsed applications, or alternatively, smaller currents for low duty cycle applications. The mechanism of storage of electric charge in a supercapacitor -- at the electrical double-layer formed at a solid-electrode/liquid-electrolyte interface -- differs from that of a primary or secondary electrochemical cell (i.e., a battery) in such a manner as to impart a long cycle life (typically >10(exp 6) charge/discharge cycles).

  9. An equation oriented approach to steady state flowsheeting of methanol synthesis loop

    International Nuclear Information System (INIS)

    Fathikalajahi, J.; Baniadam, M.; Rahimpour, M.R.

    2008-01-01

    An equation-oriented approach was developed for steady state flowsheeting of a commercial methanol plant. The loop consists of fixed bed reactor, flash separator, preheater, coolers, and compressor. For steady sate flowsheeting of the plant mathematical model of reactor and other units are needed. Reactor used in loop is a Lurgi type and its configuration is rather complex. Previously reactor and flash separator are modeled as two important units of plant. The model is based on mass and energy balances in each equipment and utilizing some auxiliary equations such as rate of reaction and thermodynamics model for activity coefficients of liquid. In order to validate the mathematical model for the synthesis loop, some simulation data were performed using operating conditions and characteristics of the commercial plant. The good agreement between the steady state simulation results and the plant data shows the validity of the model

  10. Activation of a Cu/ZnO catalyst for methanol synthesis

    DEFF Research Database (Denmark)

    Andreasen, Jens Wenzel; Rasmussen, F.B.; Helveg, S.

    2006-01-01

    The structural changes during activation by temperature-programmed reduction of a Cu/ZnO catalyst for methanol synthesis have been studied by several in situ techniques. The catalyst is prepared by coprecipitation and contains 4.76 wt% Cu, which forms a substitutional solid solution with Zn......O as determined by resonant X-ray diffraction. In situ resonant X-ray diffraction reveals that the Cu atoms are extracted from the solid solution by the reduction procedure, forming metallic Cu crystallites. Cu is redispersed in bulk or surface Zn lattice sites upon oxidation by heating in air. The results...... is highly dispersed and in intimate contact with the surface of the host ZnO particles. The possibility of re-forming the (Zn,Cu)O solid solution by oxidation may provide a means of redispersing Cu in a deactivated catalyst....

  11. Insight into the influence of liquid paraffin for methanol synthesis on Cu(110) surface using continuum and atomistic models

    Energy Technology Data Exchange (ETDEWEB)

    Jiao, Wei-Hong [Key Laboratory of Coal Science and Technology of Ministry of Education and Shanxi Province, Taiyuan University of Technology, Taiyuan 030024, Shanxi (China); Liu, Shi-Zhong [Department of Chemistry, Stony Brook University, Stony Brook, NY 11794 (United States); Zuo, Zhi-Jun, E-mail: zuozhijun@tyut.edu.cn [Key Laboratory of Coal Science and Technology of Ministry of Education and Shanxi Province, Taiyuan University of Technology, Taiyuan 030024, Shanxi (China); Ren, Rui-Peng; Gao, Zhi-Hua [Key Laboratory of Coal Science and Technology of Ministry of Education and Shanxi Province, Taiyuan University of Technology, Taiyuan 030024, Shanxi (China); Huang, Wei, E-mail: huangwei@tyut.edu.cn [Key Laboratory of Coal Science and Technology of Ministry of Education and Shanxi Province, Taiyuan University of Technology, Taiyuan 030024, Shanxi (China)

    2016-11-30

    Highlights: • The influence of liquid paraffin is studied using continuum and atomistic models. • Liquid paraffin does not alter the reaction pathways of CO hydrogenation and WGS. • Liquid paraffin alters the reaction pathways of CO{sub 2} hydrogenation. - Abstract: Methanol synthesis from CO/CO{sub 2} hydrogenation and water-gas shift (WGS) reaction on Cu(110) in liquid paraffin and vacuum have been systematically researched with density functional theory calculation (DFT). For methanol synthesis from CO hydrogenation, the reaction pathways in liquid paraffin and vacuum are CO + H → HCO → H{sub 2}CO → H{sub 3}CO → H{sub 3}COH; in the case of WGS, the reaction pathways in liquid paraffin and vacuum are CO + 2H{sub 2}O → CO + 2OH + 2H → CO + H{sub 2}O + O + H{sub 2} → CO{sub 2} + H{sub 2}O + H{sub 2}; the reaction pathways of methanol synthesis from CO{sub 2} hydrogenation in liquid paraffin and vacuum are CO{sub 2} + H → HCOO → H{sub 2}COO → H{sub 2}CO → H{sub 3}CO → H{sub 3}COH and CO{sub 2} + H → HCOO → HCOOH → H{sub 2}COOH → H{sub 3}CO → H{sub 3}COH, respectively. The result shows that liquid paraffin does not affect the reaction mechanisms of methanol synthesis from CO and WGS, but it changes the reaction mechanisms of methanol synthesis from CO{sub 2} hydrogenation. Hirshfeld charge and the d-band centers indicate that the catalytic activity of Cu(110) in liquid paraffin is smaller than that in vacuum. Our results also show that it is necessary to consider both continuum and atomistic models in the slurry bed.

  12. Synthesis of Nanocrystalline CaWO4 as Low-Temperature Co-fired Ceramic Material: Processing, Structural and Physical Properties

    Science.gov (United States)

    Vidya, S.; Solomon, Sam; Thomas, J. K.

    2013-01-01

    Nanocrystalline scheelite CaWO4, a promising material for low-temperature co-fired ceramic (LTCC) applications, has been successfully synthesized through a single-step autoignition combustion route. Structural analysis of the sample was performed by powder x-ray diffraction (XRD), Fourier-transform infrared spectroscopy, and Raman spectroscopy. The XRD analysis revealed that the as-prepared sample was single phase with scheelite tetragonal structure. The basic optical properties and optical constants of the CaWO4 nanopowder were studied using ultraviolet (UV)-visible absorption spectroscopy, which showed that the material was a wide-bandgap semiconductor with bandgap of 4.7 eV at room temperature. The sample showed poor transmittance in the ultraviolet region but maximum transmission in the visible/near-infrared regions. The photoluminescence spectra recorded at different temperatures showed intense emission in the green region. The particle size estimated from transmission electron microscopy was 23 nm. The feasibility of CaWO4 for LTCC applications was studied from its sintering behavior. The sample was sintered at a relatively low temperature of 810°C to high density, without using any sintering aid. The surface morphology of the sintered sample was analyzed by scanning electron microscopy. The dielectric constant and loss factor of the sample measured at 5 MHz were found to be 10.50 and 1.56 × 10-3 at room temperature. The temperature coefficient of the dielectric constant was -88.71 ppm/°C. The experimental results obtained in this work demonstrate the potential of nano-CaWO4 as a low-temperature co-fired ceramic as well as an excellent luminescent material.

  13. Synthesis and electrochemical performances of LiNiCuZn oxides as anode and cathode catalyst for low temperature solid oxide fuel cell.

    Science.gov (United States)

    Jing, Y; Qin, H; Liu, Q; Singh, M; Zhu, B

    2012-06-01

    Low temperature solid oxide fuel cell (LTSOFC, 300-600 degrees C) is developed with advantages compared to conventional SOFC (800-1000 degrees C). The electrodes with good catalytic activity, high electronic and ionic conductivity are required to achieve high power output. In this work, a LiNiCuZn oxides as anode and cathode catalyst is prepared by slurry method. The structure and morphology of the prepared LiNiCuZn oxides are characterized by X-ray diffraction and field emission scanning electron microscopy. The LiNiCuZn oxides prepared by slurry method are nano Li0.28Ni0.72O, ZnO and CuO compound. The nano-crystallites are congregated to form ball-shape particles with diameter of 800-1000 nm. The LiNiCuZn oxides electrodes exhibits high ion conductivity and low polarization resistance to hydrogen oxidation reaction and oxygen reduction reaction at low temperature. The LTSOFC using the LiNiCuZn oxides electrodes demonstrates good cell performance of 1000 mW cm(-2) when it operates at 470 degrees C. It is considered that nano-composite would be an effective way to develop catalyst for LTSOFC.

  14. Green synthesis of silver nanoparticles using methanolic root extracts of Diospyros paniculata and their antimicrobial activities

    International Nuclear Information System (INIS)

    Rao, N.Hanumanta; Lakshmidevi, N.; Pammi, S.V.N.; Kollu, Pratap; Ganapaty, S.; Lakshmi, P.

    2016-01-01

    Since the discovery and subsequent widespread use of antibiotics, a variety of bacterial species of human and animal origin have developed numerous mechanisms that render bacteria resistant to some, and in certain cases to nearly all antibiotics, thereby limiting the treatment options and compromising effective therapy. In the present study, the green synthesis of nanoparticles is carried out by the reduction of silver acetate in the presence of crude methanolic root extracts of Diospyros paniculata, a member of family Ebenaceae. The UV–Vis absorption spectrum of the biologically reduced reaction mixture showed the surface plasmon peak at 428 nm, a characteristic peak of silver nanoparticles. X-ray diffraction (XRD) analysis confirmed the face-centered cubic crystalline structure of metallic silver. The average diameter of Ag NPs is about 17 nm from Transmission Electron Microscopy (TEM) which is in good agreement with the average crystallite size (19 nm) calculated from XRD analysis. Further the study has been extended to the antimicrobial activity against test pathogenic Gram (+), Gram (−) bacterial and fungal strains. The biologically synthesized silver nanoparticles showed promising activity against all the tested pathogenic strains and the activity has been enhanced with the increased dose levels. - Highlights: • Biosynthesis of silver nanoparticles (Ag NPs) using root extracts of Diospyros paniculata. • Average diameter of Ag NPs is about 17 nm from TEM analysis which is in good agreement with XRD analysis. • Antimicrobial activities of root extract mediated synthesis of silver Ag NPs were discussed in detail.

  15. Green synthesis of silver nanoparticles using methanolic root extracts of Diospyros paniculata and their antimicrobial activities

    Energy Technology Data Exchange (ETDEWEB)

    Rao, N.Hanumanta [Advanced Analytical Laboratory, DST-PURSE Programme, Andhra University, Visakhapatnam 530003 (India); Lakshmidevi, N. [Department of Microbiology, College of Science and Technology, Andhra University, Visakhapatnam 530003 (India); Pammi, S.V.N. [Advanced Analytical Laboratory, DST-PURSE Programme, Andhra University, Visakhapatnam 530003 (India); Department of Materials Science and Engineering, Chungnam National University, Daeduk Science Town, 305-764, Daejeon (Korea, Republic of); Kollu, Pratap [DST-INSPIRE Faculty, Department of Metallurgical Engineering & Materials Science, Indian Institute of Technology Bombay, Mumbai 400076 (India); Ganapaty, S. [GITAM Institute of Pharmacy, GITAM University, Visakhapatnam (India); Lakshmi, P., E-mail: lmkandregula@gmail.com [Department of Microbiology, College of Science and Technology, Andhra University, Visakhapatnam 530003 (India)

    2016-05-01

    Since the discovery and subsequent widespread use of antibiotics, a variety of bacterial species of human and animal origin have developed numerous mechanisms that render bacteria resistant to some, and in certain cases to nearly all antibiotics, thereby limiting the treatment options and compromising effective therapy. In the present study, the green synthesis of nanoparticles is carried out by the reduction of silver acetate in the presence of crude methanolic root extracts of Diospyros paniculata, a member of family Ebenaceae. The UV–Vis absorption spectrum of the biologically reduced reaction mixture showed the surface plasmon peak at 428 nm, a characteristic peak of silver nanoparticles. X-ray diffraction (XRD) analysis confirmed the face-centered cubic crystalline structure of metallic silver. The average diameter of Ag NPs is about 17 nm from Transmission Electron Microscopy (TEM) which is in good agreement with the average crystallite size (19 nm) calculated from XRD analysis. Further the study has been extended to the antimicrobial activity against test pathogenic Gram (+), Gram (−) bacterial and fungal strains. The biologically synthesized silver nanoparticles showed promising activity against all the tested pathogenic strains and the activity has been enhanced with the increased dose levels. - Highlights: • Biosynthesis of silver nanoparticles (Ag NPs) using root extracts of Diospyros paniculata. • Average diameter of Ag NPs is about 17 nm from TEM analysis which is in good agreement with XRD analysis. • Antimicrobial activities of root extract mediated synthesis of silver Ag NPs were discussed in detail.

  16. Synthesis and characterization of ternary Pt-Ni-M/C (M=Cu, Fe, Ce, Mo, W) nano-catalysts for low temperature fuel cells

    International Nuclear Information System (INIS)

    Ahmed, Riaz; Jamil, Rabia; Ansari, Muhammad Shahid

    2014-01-01

    Ternary metal catalysts were synthesized by impregnation method. The mixture of metal solutions was reduced slowly under inert atmosphere and the reduced metals were deposited on the Vulcan Carbon(VC). Tungsten, molybdenum, cerium, iron and copper were added to specified amounts of platinum and nickel. Addition of nickel generally improves catalytic activity of platinum. The XRD of the catalysts was done and the crystallite size and other parameters were calculated. Crystallite sizes were in the range of 5 to 16 nm. Electrochemical surface areas of the catalysts were determined by cyclic voltammetry (CV) in acidic media and are compared. Electro oxidation of methanol on the catalysts was done and peak potential, peak current, mass activity of the catalysts were calculated and are compared. These parameters were determined in acidic and basic media. It was found that mass activity increased significantly in basic media. Rate constants for the electro oxidation of methanol were also calculated in acidic and basic media and are compared and discussed. Rate constants were generally higher in basic media. Ternary catalysts showed improved catalytic activity than the binary catalyst. Nano alloying improved the catalytic activity and stability of the ternary catalysts

  17. Synthesis and characterization polymer composites prepared by low-temperature post-irradiation polymerization of C_2F_4 in the presence of graphene-like material

    International Nuclear Information System (INIS)

    Shulga, Y.M.; Kiryukhin, D.P.; Vasilets, V.N.

    2015-01-01

    Polymer polytetrafluoroethylene (Ptfe)-microwave exfoliated graphene oxide (MEGO) composites containing up to 80 wt.% PTFE were prepared by low-temperature post-irradiation polymerization of C_2F_4 in the presence of the graphene-like material. Composites were characterized by elemental analysis, XPS, NMR, and DSC techniques. The melting point of PTFE in the composite (332.5°C) was higher than that of pure PTFE by 8.8°C. The measured values of the melting enthalpy (ΔHm=51.5 and 45.4 J/g) were used to calculate the extent of crystallinity in the PTFE and PTFE-MEGO composite (0.63 and 0.55, respectively). No - CF_3 end groups typical of commercial PTFE have been detected in the PTFE-MEGO composites. (authors)

  18. Synthesis and characterization of Ba_0_._5Pb_0_._5TiO_3 perovskite - type thin films deposited by spin coating at low temperatures

    International Nuclear Information System (INIS)

    Wermuth, T.B.; Wiederkehr, N.A.; Alves, A.K.; Bergmann, C.P.

    2014-01-01

    In this paper we present a non-aqueous sol-gel route for the obtention of solid compounds and thin films of oxide type- perovskite ABO_3, such as Ba_0_._5 Pb_0_._5 TiO_3, synthesized by sol - gel route with subsequent heat treatment. The solid compounds were characterized by X-ray diffraction (XRD) techniques and thermal analysis (TGA / DTA). The thin film was obtained by using spin-coating techniques at low temperatures onto commercial substrates of polymethylmethacrylate (PMMA) and characterized by contact angle, atomic force microscopy (AFM) and scanning electron microscopy (SEM). The results show that the films present microstructures and roughness directly related to annealing temperatures, characterized by the formation of crystalline nanostructures with surface regularity and transparency. (author)

  19. Low-temperature synthesis, structural and magnetic properties of self-dopant LaMnO{sub 3+δ} nanoparticles from a metal-organic polymeric precursor

    Energy Technology Data Exchange (ETDEWEB)

    Ahmad, Tokeer, E-mail: tahmad3@jmi.ac.in [Nanochemistry Laboratory, Department of Chemistry, Jamia Millia Islamia, New Delhi 110025 (India); Lone, Irfan H.; Ubaidullah, Mohd. [Nanochemistry Laboratory, Department of Chemistry, Jamia Millia Islamia, New Delhi 110025 (India); Coolhan, Kelsey [Department of Physics and Astronomy, Rowan University, 201 Mullica Hill Road, Glassboro, NJ 08028 (United States)

    2013-11-15

    Graphical abstract: Monophasic and highly crystalline Self-dopant LaMnO{sub 3+δ} nanoparticles (72 nm) have been successfully synthesized at low temperature (773 K) by metal citrate complex method based on Pechini-type reaction route which showed ferromagnetic interaction. Surface areas of LaMnO{sub 3+δ} nanoparticles were found to be 157.4 and 153 m{sup 2} g{sup −1} for the samples annealed at 773 K and 1173 K, respectively. - Highlights: • Self-dopant LaMnO{sub 3+δ} nanoparticles using Pechini-type reaction route at 773 K. • Size range varies from 72 to 80 nm. • Surface area varies from 153 to 157 m{sup 2} g{sup −1}. • Extensive characterization using sophisticated techniques. - Abstract: Self-dopant LaMnO{sub 3+δ} nanoparticles have been successfully synthesized by metal citrate complex method based on Pechini-type reaction route, at low temperature (773 K). Powder X-ray diffraction and transmission electron microscope revealed pure and nanostructured phase of LaMnO{sub 3+δ} (δ = 0.125) with an average grain size of ∼72 nm (773 K) and ∼80 nm (1173 K). DC-magnetization measurements under an applied magnetic field of H = ±60 kOe showed an increase in the magnetization with the increase of calcination temperature. Ferromagnetic nature shown by non-stoichiometric LaMnO{sub 3+δ} was verified by well-defined hysteresis loop with large remanent magnetization (M{sub r}) and coercive field (H{sub c}). Surface areas of LaMnO{sub 3+δ} nanoparticles were found to be 157.4 and 153 m{sup 2} g{sup −1} for the samples annealed at 773 K and 1173 K, respectively.

  20. Low-temperature synthesis, phonon and luminescence properties of Eu doped Y{sub 3}Al{sub 5}O{sub 12} (YAG) nanopowders

    Energy Technology Data Exchange (ETDEWEB)

    Mączka, M., E-mail: m.maczka@int.pan.wroc.pl [Institute of Low Temperature and Structure Research, Polish Academy of Sciences, P.O. Box 1410, 50-950 Wrocław 2 (Poland); Bednarkiewicz, A. [Institute of Low Temperature and Structure Research, Polish Academy of Sciences, P.O. Box 1410, 50-950 Wrocław 2 (Poland); Mendoza-Mendoza, E.; Fuentes, A.F. [Cinvestav Unidad Saltillo, Apartado Postal 663, 25000 Saltillo, Coahuila (Mexico); Kępiński, L. [Institute of Low Temperature and Structure Research, Polish Academy of Sciences, P.O. Box 1410, 50-950 Wrocław 2 (Poland)

    2014-02-14

    This contribution presents two simple and cost-effective routes for the low-temperature and large-scale production of pure and Eu-doped Y{sub 3}Al{sub 5}O{sub 12} (yttrium aluminum garnet YAG) nanopowders. The proposed methodologies combine a mechanically assisted metathesis reaction or coprecipitation from solution followed by crystallization of the obtained precursors from molten sodium nitrate/nitrite. Both procedures allow obtaining pure and/or doped YAG nanopowders at remarkably low temperatures, i.e. already at 350 °C although firing at 500 °C is needed in order to get single phase and fully crystalline materials. As-obtained samples were characterized by XRD, TEM, Raman, IR and luminescence methods. These methods showed that the mean crystallite size is near 23–31 and 51 nm, when crystallization is performed from the amorphous precursor obtained by a mechanically assisted metathesis reaction and coprecipitation, respectively. Raman and IR spectra indicated better crystallinity of the powders prepared at 500 °C. The emission study showed that the intensity ratio between hypersensitive {sup 5}D{sub 0} → {sup 7}F{sub 2} and magnetic-dipole {sup 5}D{sub 0} → {sup 7}F{sub 1} transitions of Eu{sup 3+} is significantly larger than expected for well-crystallized YAG. Origin of this behavior is discussed. - Highlights: • Nanoparticles of Y{sub 3}Al{sub 5}O{sub 12} (YAG) and YAG:Eu{sup 3+} have been prepared at remarkable 350 °C. • Metathesis/molten salts and coprecipitation/molten salts methods were used. • Metathesis/molten salts method is suitable for preparation of rare-earth doped YAG. • Emission properties of YAG:Eu{sup 3+} are significantly different from bulk YAG.

  1. Synthesis of highly active and dual-functional electrocatalysts for methanol oxidation and oxygen reduction reactions

    Energy Technology Data Exchange (ETDEWEB)

    Zhao, Qi; Zhang, Geng; Xu, Guangran; Li, Yingjun [College of Chemistry and Chemical Engineering, Inner Mongolia University, Hohhot 010021 (China); Liu, Baocang [College of Chemistry and Chemical Engineering, Inner Mongolia University, Hohhot 010021 (China); Inner Mongolia Key Lab of Nanoscience and Nanotechnology, Inner Mongolia University, Hohhot 010021 (China); Gong, Xia [College of Chemistry and Chemical Engineering, Inner Mongolia University, Hohhot 010021 (China); Zheng, Dafang [State Key Laboratory of Inorganic Synthesis and Preparative Chemistry, College of Chemistry, Jilin University, Changchun 130012 (China); Zhang, Jun [College of Chemistry and Chemical Engineering, Inner Mongolia University, Hohhot 010021 (China); Inner Mongolia Key Lab of Nanoscience and Nanotechnology, Inner Mongolia University, Hohhot 010021 (China); Wang, Qin, E-mail: qinwang@imu.edu.cn [College of Chemistry and Chemical Engineering, Inner Mongolia University, Hohhot 010021 (China); Inner Mongolia Key Lab of Nanoscience and Nanotechnology, Inner Mongolia University, Hohhot 010021 (China)

    2016-12-15

    Graphical abstract: Ternary RuMPt (M = Fe, Co, Ni, and Cu) nanodendrities (NDs) catalysts, are successfully synthesized by using a facile method. The as-obtained ternary catalysts manifest superior catalytic activity and stability both in terms of surface and mass specific activities toward the methanol oxidation and oxygen reduction reactions, as compared to the binary catalysts and the commercial Pt/C catalysts. - Highlights: • Ternary RuMPt catalysts are synthesized by using a facile method. • The catalysts manifest superior catalytic activity towards the MOR and ORR. • High activities are attributed to enhanced electron density and synergistic effects. - Abstract: The promising Pt-based ternary catalyst is crucial for polymer electrolyte membrane fuel cells (PEMFCs) due to improving catalytic activity and durability for both methanol oxidation reaction and oxygen reduction reaction. In this work, a facile strategy is used for the synthesis ternary RuMPt (M = Fe, Co, Ni, and Cu) nanodendrities catalysts. The ternary RuMPt alloys exhibit enhanced specific and mass activity, positive half-wave potential, and long-term stability, compared with binary Pt-based alloy and the commercial Pt/C catalyst, which is attributed to the high electron density and upshifting of the d-band center for Pt atoms, and synergistic catalytic effects among Pt, M, and Ru atoms by introducing a transition metal. Impressively, the ternary RuCoPt catalyst exhibits superior mass activity (801.59 mA mg{sup −1}) and positive half-wave potential (0.857 V vs. RHE) towards MOR and ORR, respectively. Thus, the RuMPt nanocomposite is a very promising material to be used as dual electrocatalyst in the application of PEMFCs.

  2. Low Temperature Synthesis, Chemical and Electrochemical Characterization of LiNi(x)Co(1-x)O2 (0 less than x less than 1)

    Science.gov (United States)

    Nanjundaswamy, K. S.; Standlee, D.; Kelly, C. O.; Whiteley, R. V., Jr.

    1997-01-01

    A new method of synthesis for the solid solution cathode materials LiNi(x)Co(1-x)O2 (0 less than x less than 1) involving enhanced reactions at temperatures less than or equal to 700 deg. C, between metal oxy-hydroxide precursors MOOH (M = Ni, Co) and Li-salts (Li2CO3, LiOH, and LiNO3) has been investigated. The effects of synthesis conditions and sources of Li, on phase purity, microstructure, and theoretical electrochemical capacity (total M(3+) content) are characterized by powder X-ray diffraction analysis, scanning electron microscopy, chemical analysis and room temperature magnetic susceptibility. An attempt has been made to correlate the electrochemical properties with the synthesis conditions and microstructure.

  3. Reverse Topotactic Transformation of a Cu–Zn–Al Catalyst during Wet Pd Impregnation : Relevance for the Performance in Methanol Synthesis from CO2/H2 Mixtures

    NARCIS (Netherlands)

    Fierro, J.L.G.; López Granados, M.; Melián-Cabrera, I.

    2002-01-01

    The effect of palladium metal on the performance of a CuO–ZnO–Al2O3 catalyst is studied for methanol synthesis by hydrogenation of carbon dioxide. The dramatic decrease in the methanol yield (in mol CH3OH/h · gcat) seen for the Pd-containing catalysts is discussed in terms of formation,

  4. Nitrogen doped graphene supported palladium-cobalt as a promising catalyst for methanol oxidation reaction: Synthesis, characterization and electrocatalytic performance

    International Nuclear Information System (INIS)

    Kiyani, Roya; Rowshanzamir, Soosan; Parnian, Mohammad Javad

    2016-01-01

    In this work, palladium and palladium-cobalt supported on nitrogen doped graphene as anode materials in direct methanol fuel cells is reported. A simple and low temperature solvothermal method is used to directly prepare nanoflower-like NG and then, Pd and Pd−Co nanoparticles are precipitated onto the surface of NG using a modified polyol reduction method. The synthesized electrocatalysts are characterized using scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD), Raman spectroscopy, and X-ray photoelectron spectroscopy (XPS). Cyclic voltammetry (CV), linear sweep voltammetry (LSV), chronoamperometry (CA), and electrochemical impedance spectroscopy (EIS) are used to measure electrocatalytic methanol oxidation activity and the durability of electrocatalysts. The results show that Pd−Co/NG has better electrocatalytic activity than Pd/NG toward methanol oxidation reaction (MOR) in alkaline media that is related at the presence of cobalt atoms. In addition, chronoamperometric results indicate that Pd−Co/NG is more stable than commercial Pt/C for MOR. - Highlights: • Nitrogen doped graphene (NG) was prepared by a simple solvothermal method. • Pd and Pd−Co nanoparticles were deposited on NG by polyol reduction method. • Promoting effects of cobalt over Pd/NG for MOR were investigated. • Higher activity and enhanced durability was observed for Pd−Co/NG catalyst.

  5. Low-Temperature Sol-Gel Synthesis of Nitrogen-Doped Anatase/Brookite Biphasic Nanoparticles with High Surface Area and Visible-Light Performance

    Directory of Open Access Journals (Sweden)

    Liang Jiang

    2017-12-01

    Full Text Available Nitrogen doping in combination with the brookite phase or a mixture of TiO2 polymorphs nanomaterials can enhance photocatalytic activity under visible light. Generally, nitrogen-dopedanatase/brookite mixed phases TiO2 nanoparticles obtained by hydrothermal or solvothermal method need to be at high temperature and with long time heating treatment. Furthermore, the surface areas of them are low (<125 m2/g. There is hardly a report on the simple and direct preparation of N-doped anatase/brookite mixed phase TiO2 nanostructures using sol-gel method at low heating temperature. In this paper, the nitrogen-doped anatase/brookite biphasic nanoparticles with large surface area (240 m2/g were successfully prepared using sol-gel method at low temperature (165 °C, and with short heating time (4 h under autogenous pressure. The obtained sample without subsequent annealing at elevated temperatures showed enhanced photocatalytic efficiency for the degradation of methyl orange (MO with 4.2-, 9.6-, and 7.5-fold visible light activities compared to P25 and the amorphous samples heated in muffle furnace with air or in tube furnace with a flow of nitrogen at 165 °C, respectively. This result was attributed to the synergistic effects of nitrogen doping, mixed crystalline phases, and high surface area.

  6. Spontaneous Synthesis of Highly Crystalline TiO2 Compact/Mesoporous Stacked Films by a Low-Temperature Steam-Annealing Method for Efficient Perovskite Solar Cells.

    Science.gov (United States)

    Sanehira, Yoshitaka; Numata, Youhei; Ikegami, Masashi; Miyasaka, Tsutomu

    2018-05-23

    Highly crystalline TiO 2 nanostructured films were synthesized by a simple steam treatment of a TiCl 4 precursor film under a saturated water vapor atmosphere at 125 °C, here referred to as the steam-annealing method. In a single TiO 2 film preparation step, a bilayer structure comprising a compact bottom layer and a mesoporous surface layer was formed. The mesoporous layer was occupied by bipyramidal nanoparticles, with a composite phase of anatase and brookite crystals. Despite the low-temperature treatment process, the crystallinity of the TiO 2 film was high, comparable with that of the TiO 2 film sintered at 500 °C. The compact double-layered TiO 2 film was applied to perovskite solar cells (PSCs) as an electron-collecting layer. The PSC exhibited a maximum power conversion efficiency (PCE) of 18.9% with an open-circuit voltage ( V OC ) of 1.15 V. The PCE and V OC were higher than those of PSCs using a TiO 2 film formed by 500 °C sintering.

  7. Feasibility study on blast furnace ironmaking system integrated with methanol synthesis for reduction of carbon dioxide emission with effective use of energy

    Energy Technology Data Exchange (ETDEWEB)

    Akiyama, T [and others; Tohoku University, Sendai (Japan)

    1993-01-01

    The system proposed involves injection of natural gas at the tuyeres to reduce coke consumption, and methanol synthesis from the top gas. Operating data are calculated with a mathematical model, showing that significant reductions in emission of greenhouse gases and in exergy losses can be expected. (Development of an effective catalyst for the methanol synthesis is described in a companion paper: A. Muramatsu et al., 1144-1149).

  8. Green synthesis of silver nanoparticles using methanolic root extracts of Diospyros paniculata and their antimicrobial activities.

    Science.gov (United States)

    Rao, N Hanumanta; N, Lakshmidevi; Pammi, S V N; Kollu, Pratap; S, Ganapaty; P, Lakshmi

    2016-05-01

    Since the discovery and subsequent widespread use of antibiotics, a variety of bacterial species of human and animal origin have developed numerous mechanisms that render bacteria resistant to some, and in certain cases to nearly all antibiotics, thereby limiting the treatment options and compromising effective therapy. In the present study, the green synthesis of nanoparticles is carried out by the reduction of silver acetate in the presence of crude methanolic root extracts of Diospyros paniculata, a member of family Ebenaceae. The UV-Vis absorption spectrum of the biologically reduced reaction mixture showed the surface plasmon peak at 428 nm, a characteristic peak of silver nanoparticles. X-ray diffraction (XRD) analysis confirmed the face-centered cubic crystalline structure of metallic silver. The average diameter of Ag NPs is about 17 nm from Transmission Electron Microscopy (TEM) which is in good agreement with the average crystallite size (19 nm) calculated from XRD analysis. Further the study has been extended to the antimicrobial activity against test pathogenic Gram (+), Gram (-) bacterial and fungal strains. The biologically synthesized silver nanoparticles showed promising activity against all the tested pathogenic strains and the activity has been enhanced with the increased dose levels. Copyright © 2016 Elsevier B.V. All rights reserved.

  9. Synthesis and Low Temperature Spectroscopic Observation of 1,3,5-Trioxane-2,4,6-Trione: The Cyclic Trimer of Carbon Dioxide

    Science.gov (United States)

    2016-08-19

    Dewar flask with a viewing window feature. A 5% O3/O2 mixture from the ozone generator (10 V coronal discharge ) was delivered to the cold solution...orthocarbonate extended covalent structure of interconnected six-membered rings was predicted by model calculation with the finding of a stabilization energy...stability. The approach is that of a model compound synthesis where the trioxane ring is first generated from substituted aldehydes and then the

  10. Low-temperature synthesis and characterization of anatase TiO2 nanoparticles by an acid assisted sol–gel method

    International Nuclear Information System (INIS)

    Leyva-Porras, C.; Toxqui-Teran, A.; Vega-Becerra, O.; Miki-Yoshida, M.; Rojas-Villalobos, M.; García-Guaderrama, M.

    2015-01-01

    The synthesis of anatase TiO 2 nanoparticles by an acid-assisted sol–gel method at 25 and 80 °C is described. Specifically, acetic acid (AA) was used and the evolution of the anatase phase with the amount of AA was observed. The results of X-ray diffraction (XRD) and transmission electron microscopy (TEM) both showed that a pure anatase phase was obtained with particle size smaller than 5 nm. Structural refinements and quantitative determination of phase composition was achieved by using the Rietveld method. The particle size distribution became slightly narrower as the amount of AA was increased. Raman spectroscopy showed that when the amount of AA was increased a small amount of brookite was present at the contamination level. The anatase phase was studied by differential thermal analysis (DTA), providing phase stability up to 600 °C. These and other results were discussed in terms of particle size and structure. Likewise, the formation of the anatase phase under these synthesis conditions was explained. - Highlights: • Synthesis of anatase TiO 2 nanoparticles by an acid assisted sol–gel method at mild conditions. • Microstructure characterization by XRD, TEM and Raman spectroscopy. • Observation of the formation and evolution of the anatase phase as acetic acid was increased. • Anatase thermal stability up to 600 °C and band gap range between 3.2 and 3.5 eV. • A simplified method which can be considered as a green chemistry process

  11. A study of Cu/ZnO/Al2O3 methanol catalysts prepared by flame combustion synthesis

    DEFF Research Database (Denmark)

    Jensen, Joakim Reimer; Johannessen, Tue; Wedel, Stig

    2003-01-01

    The flame combustion synthesis of Cu/ZnO/Al2O3 catalysts for the synthesis of methanol from CO, CO2 and H2 is investigated. The oxides are generated in a premixed flame from the acetyl-acetonate vapours of Cu, Zn and Al mixed with the fuel and air prior to combustion. The flame-generated powder...... temperature and quench-cooling of the flame tend to increase the dispersion of the phases and the specific surface area of the particles. Properties of both the ternary composition, the three binary compositions and the pure oxides are discussed. The calculation of simultaneous phase and chemical equilibrium...

  12. Vacuum-Assisted Low-Temperature Synthesis of Reduced Graphene Oxide Thin-Film Electrodes for High-Performance Transparent and Flexible All-Solid-State Supercapacitors.

    Science.gov (United States)

    Aytug, Tolga; Rager, Matthew S; Higgins, Wesley; Brown, Forrest G; Veith, Gabriel M; Rouleau, Christopher M; Wang, Hui; Hood, Zachary D; Mahurin, Shannon M; Mayes, Richard T; Joshi, Pooran C; Kuruganti, Teja

    2018-04-04

    Simple and easily integrated design of flexible and transparent electrode materials affixed to polymer-based substrates hold great promise to have a revolutionary impact on the functionality and performance of energy storage devices for many future consumer electronics. Among these applications are touch sensors, roll-up displays, photovoltaic cells, health monitors, wireless sensors, and wearable communication devices. Here, we report an environmentally friendly, simple, and versatile approach to produce optically transparent and mechanically flexible all-solid-state supercapacitor devices. These supercapacitors were constructed on tin-doped indium oxide coated polyethylene terephthalate substrates by intercalation of a polymer-based gel electrolyte between two reduced graphene oxide (rGO) thin-film electrodes. The rGO electrodes were fabricated simply by drop-casting of graphene oxide (GO) films, followed by a novel low-temperature (≤250 °C) vacuum-assisted annealing approach for the in situ reduction of GO to rGO. A trade-off between the optical transparency and electrochemical performance is determined by the concentration of the GO in the initial dispersion, whereby the highest capacitance (∼650 μF cm -2 ) occurs at a relatively lower optical transmittance (24%). Notably, the all-solid-state supercapacitors demonstrated excellent mechanical flexibility with a capacity retention rate above 90% under various bending angles and cycles. These attributes underscore the potential of the present approach to provide a path toward the realization of thin-film-based supercapacitors as flexible and transparent energy storage devices for a variety of practical applications.

  13. Synthesis of submicron silver powder from scrap low-temperature co-fired ceramic an e-waste: Understanding the leaching kinetics and wet chemistry.

    Science.gov (United States)

    Swain, Basudev; Shin, Dongyoon; Joo, So Yeong; Ahn, Nak Kyoon; Lee, Chan Gi; Yoon, Jin-Ho

    2018-03-01

    The current study focuses on the understanding of leaching kinetics of metal in the LTCC in general and silver leaching in particular along with wet chemical reduction involving silver nanoparticle synthesis. Followed by metal leaching, the silver was selectively precipitated using HCl as AgCl. The precipitated AgCl was dissolved in ammonium hydroxide and reduced to pure silver metal nanopowder (NPs) using hydrazine as a reductant. Polyvinylpyrrolidone (PVP) used as a stabilizer and Polyethylene glycol (PEG) used as reducing reagent as well as stabilizing reagent to control size and shape of the Ag NPs. An in-depth investigation indicated a first-order kinetics model fits well with high accuracy among all possible models. Activation energy required for the first order reaction was 21.242 kJ mol -1 for Silver. PVP and PEG 1% each together provide better size control over silver nanoparticle synthesis using 0.4 M hydrazine as reductant, which provides relatively regular morphology in comparison to their individual application. The investigation revealed that the waste LTCC (an industrial e-waste) can be recycled through the reported process even in industrial scale. The novelty of reported recycling process is simplicity, versatile and eco-efficiency through which waste LTCC recycling can address various issues like; (i) industrial waste disposal (ii) synthesis of silver nanoparticles from waste LTCC (iii) circulate metal economy within a closed loop cycle in the industrial economies where resources are scarce, altogether. Copyright © 2017 Elsevier Ltd. All rights reserved.

  14. Low-temperature synthesis and characterization of anatase TiO{sub 2} nanoparticles by an acid assisted sol–gel method

    Energy Technology Data Exchange (ETDEWEB)

    Leyva-Porras, C. [Centro de Investigación en Materiales DIP-CUCEI, Universidad de Guadalajara, Av. Revolución # 1500, Col. Olímpica, C.P. 44430, Guadalajara (Mexico); Centro de Investigación en Materiales Avanzados, S.C. (CIMAV), Alianza Norte No. 202, Parque de Investigación e Innovación Tecnológica (PIIT), Carretera Aeropuerto km. 10, C.P. 66600, Apodaca, N.L. (Mexico); Toxqui-Teran, A.; Vega-Becerra, O. [Centro de Investigación en Materiales Avanzados, S.C. (CIMAV), Alianza Norte No. 202, Parque de Investigación e Innovación Tecnológica (PIIT), Carretera Aeropuerto km. 10, C.P. 66600, Apodaca, N.L. (Mexico); Miki-Yoshida, M. [Centro de Investigación en Materiales Avanzados, S.C. (CIMAV), Miguel de Cervantes No. 120, Parque Industrial Chihuahua, C.P. 31109, Chihuahua (Mexico); Rojas-Villalobos, M.; García-Guaderrama, M. [Centro de Investigación en Materiales DIP-CUCEI, Universidad de Guadalajara, Av. Revolución # 1500, Col. Olímpica, C.P. 44430, Guadalajara (Mexico); and others

    2015-10-25

    The synthesis of anatase TiO{sub 2} nanoparticles by an acid-assisted sol–gel method at 25 and 80 °C is described. Specifically, acetic acid (AA) was used and the evolution of the anatase phase with the amount of AA was observed. The results of X-ray diffraction (XRD) and transmission electron microscopy (TEM) both showed that a pure anatase phase was obtained with particle size smaller than 5 nm. Structural refinements and quantitative determination of phase composition was achieved by using the Rietveld method. The particle size distribution became slightly narrower as the amount of AA was increased. Raman spectroscopy showed that when the amount of AA was increased a small amount of brookite was present at the contamination level. The anatase phase was studied by differential thermal analysis (DTA), providing phase stability up to 600 °C. These and other results were discussed in terms of particle size and structure. Likewise, the formation of the anatase phase under these synthesis conditions was explained. - Highlights: • Synthesis of anatase TiO{sub 2} nanoparticles by an acid assisted sol–gel method at mild conditions. • Microstructure characterization by XRD, TEM and Raman spectroscopy. • Observation of the formation and evolution of the anatase phase as acetic acid was increased. • Anatase thermal stability up to 600 °C and band gap range between 3.2 and 3.5 eV. • A simplified method which can be considered as a green chemistry process.

  15. Low temperature synthesis of N-doped TiO_2 with rice-like morphology through peroxo assisted hydrothermal route: Materials characterization and photocatalytic properties

    International Nuclear Information System (INIS)

    Bakar, Shahzad Abu; Ribeiro, Caue

    2016-01-01

    Highlights: • The N:TiO_2 nanorice were prepared using facile peroxo-assisted hydrothermal method at low temperature. • The N:TiO_2 exhibited rice-like morphology. • The nitrogen doping favoured UV/visible light photocatalytic activity. • The RhB and Atrazine were chosen as model pollutants. - Abstract: Nanorice-shaped N:TiO_2 photocatalysts have been prepared by the peroxo assisted hydrothermal method using stabilized titanium complex as a precursor and urea as a N source. The N:TiO_2 nanorices were characterised by XRD, FE-SEM, HRTEM, XPS, UV–vis spectroscopy, Raman spectroscopy and measurements of photocatalytic degradation of organic molecules (atrazine and RhB dye) under the UV and visible-light irradiation. XRD analyses showed that pristine TiO_2 crystallizes into anatase polymorph and that the N-doping process at 5% introduced a degree of disorder on the TiO_2 crystalline structure. XPS study revealed the successful incorporation of the nitrogen atoms at the interstitial sites of the TiO_2 crystal lattice. Microscopy studies revealed that the particle size was in the range 50–80 nm for the pristine TiO_2. The photocatalysts were assembled in the form of nanorices with a high surface area (102 m"2 g"−"1). The successful incorporation of nitrogen atoms into the TiO_2 crystal lattice is expected to be responsible for enhanced photocatalytic activity of the as-prepared samples for the degradation of pollutants (RhB and atrazine) under UV and visible light irradiation. The rate of ·OH radicals formation under visible-light irradiation was examined and found to be correlated with the photocatalytic activity per unit surface area. The N:TiO_2 particles with nanorice morphology was efficient photocatalysts for decomposition of organic dyes under UV and visible-light exposure while pristine TiO_2 photocatalyst did not show any significant photocatalytic activity when stimulated by visible-light. The 3% doped N:TiO_2 sample exhibited the highest

  16. Low temperature synthesis of N-doped TiO{sub 2} with rice-like morphology through peroxo assisted hydrothermal route: Materials characterization and photocatalytic properties

    Energy Technology Data Exchange (ETDEWEB)

    Bakar, Shahzad Abu, E-mail: shahzad.158@gmail.com [Department of Chemistry, Federal University of São Carlos, Washington Luiz Highway, km 235, 13565-905 São Carlos, SP (Brazil); Embrapa CNPDIA, XV de Novembro Street, 1452, CP 741, 13560-970 São Carlos, SP (Brazil); Ribeiro, Caue [Embrapa CNPDIA, XV de Novembro Street, 1452, CP 741, 13560-970 São Carlos, SP (Brazil)

    2016-07-30

    Highlights: • The N:TiO{sub 2} nanorice were prepared using facile peroxo-assisted hydrothermal method at low temperature. • The N:TiO{sub 2} exhibited rice-like morphology. • The nitrogen doping favoured UV/visible light photocatalytic activity. • The RhB and Atrazine were chosen as model pollutants. - Abstract: Nanorice-shaped N:TiO{sub 2} photocatalysts have been prepared by the peroxo assisted hydrothermal method using stabilized titanium complex as a precursor and urea as a N source. The N:TiO{sub 2} nanorices were characterised by XRD, FE-SEM, HRTEM, XPS, UV–vis spectroscopy, Raman spectroscopy and measurements of photocatalytic degradation of organic molecules (atrazine and RhB dye) under the UV and visible-light irradiation. XRD analyses showed that pristine TiO{sub 2} crystallizes into anatase polymorph and that the N-doping process at 5% introduced a degree of disorder on the TiO{sub 2} crystalline structure. XPS study revealed the successful incorporation of the nitrogen atoms at the interstitial sites of the TiO{sub 2} crystal lattice. Microscopy studies revealed that the particle size was in the range 50–80 nm for the pristine TiO{sub 2}. The photocatalysts were assembled in the form of nanorices with a high surface area (102 m{sup 2} g{sup −1}). The successful incorporation of nitrogen atoms into the TiO{sub 2} crystal lattice is expected to be responsible for enhanced photocatalytic activity of the as-prepared samples for the degradation of pollutants (RhB and atrazine) under UV and visible light irradiation. The rate of ·OH radicals formation under visible-light irradiation was examined and found to be correlated with the photocatalytic activity per unit surface area. The N:TiO{sub 2} particles with nanorice morphology was efficient photocatalysts for decomposition of organic dyes under UV and visible-light exposure while pristine TiO{sub 2} photocatalyst did not show any significant photocatalytic activity when stimulated by visible

  17. Methanol Synthesis: Optimal Solution for a Better Efficiency of the Process

    Directory of Open Access Journals (Sweden)

    Grazia Leonzio

    2018-02-01

    Full Text Available In this research, an ANOVA analysis and a response surface methodology are applied to analyze the equilibrium of methanol reaction from pure carbon dioxide and hydrogen. In the ANOVA analysis, carbon monoxide composition in the feed, reaction temperature, recycle and water removal through a zeolite membrane are the analyzed factors. Carbon conversion, methanol yield, methanol productivity and methanol selectivity are the analyzed responses. Results show that main factors have the same effect on responses and a common significant interaction is not present. Carbon monoxide composition and water removal have a positive effect, while temperature and recycle have a negative effect on the system. From central composite design, an optimal solution is found in order to overcome thermodynamic limit: the reactor works with a membrane at lower temperature with carbon monoxide composition in the feed equal to 10 mol % and without recycle. In these conditions, carbon conversion, methanol yield, methanol selectivity, and methanol production are, respectively, higher than 60%, higher than 60%, between 90% and 95% and higher than 0.15 mol/h when considering a feed flow rate of 1 mol/h. A comparison with a traditional reactor is also developed: the membrane reactor ensures to have a carbon conversion higher of the 29% and a methanol yield higher of the 34%. Future researches should evaluate an economic analysis about the optimal solution.

  18. A DFT approach for methanol synthesis via hydrogenation of CO on gallia, ceria and ZnO surfaces

    Science.gov (United States)

    Reimers, Walter; Zubieta, Carolina; Baltanás, Miguel Angel; Branda, María Marta

    2018-04-01

    A systematic theoretical study of the consecutive hydrogenation reactions of the CO molecule for the methanol synthesis catalyzed by different oxides of Zn, Ce and Ga is reported in this work. First, the CO hydrogenation with the formation of formyl species (HCO) was analyzed, followed by the successive hydrogenations that lead to formaldehyde (H2CO), methoxy (H3CO) and, finally, methanol (H3COH). The co-adsorption with H, in almost all the intermediate species, allows the corresponding hydrogenation reaction. Oxygen vacancies promote the reactivity in the generation of both formaldehyde and methoxy species. The formation of these species involves an important geometric difference between the initial and the final states, leading to high activation barriers. Comparing the surfaces studied in this work, we found that ZnO (0001)vacO has shown to be of a greater interest for methanol synthesis. However, the foregoing is not the most relevant of our results, but, instead, that the Brönsted Evans Polanyi (BEP) relationships between the initial or the final states and the transition states (TS) allowed to find a very good correlation between surface structure and reactivity.

  19. Mesoporous silica materials modified with alumina polycations as catalysts for the synthesis of dimethyl ether from methanol

    Energy Technology Data Exchange (ETDEWEB)

    Macina, Daniel; Piwowarska, Zofia; Tarach, Karolina; Góra-Marek, Kinga [Jagiellonian University, Faculty of Chemistry, Ingardena 3, 30-060 Kraków (Poland); Ryczkowski, Janusz [Maria Curie Skłodowska University, Faculty of Chemistry, Maria Curie-Skłodowska 2, 20-031 Lublin (Poland); Chmielarz, Lucjan, E-mail: chmielar@chemia.uj.edu.pl [Jagiellonian University, Faculty of Chemistry, Ingardena 3, 30-060 Kraków (Poland)

    2016-02-15

    Highlights: • Deposition of alumina ologoctaions on mesoporous silicas modified with surface −SO{sub 3}H groups. • Alumina aggregates generated acid properties in the silica supports. • Alumina modified SBA-15 and MCF were active and selective catalysts in DME synthesis. - Abstract: Mesoporous silica materials (SBA-15 and MCF) were used as catalytic supports for the deposition of aggregated alumina species using the method consisting of the following steps: (i) anchoring 3-(mercaptopropyl)trimethoxysilane (MPTMS) on the silica surface followed by (ii) oxidation of −SH to−SO{sub 3}H groups and then (iii) deposition of aluminum Keggin oligocations by ion-exchange method and (iv) calcination. The obtained samples were tested as catalysts for synthesis of dimethyl ether from methanol. The modified silicas were characterized with respect to the ordering of their porous structure (XRD), textural properties (BET), chemical composition (EDS, CHNS), structure ({sup 27}Al NMR, FTIR) and location of alumina species (EDX-TEM), surface acidity (NH{sub 3}-TPD, Py-FTIR) and thermal stability (TGA). The obtained materials were found to be active and selective catalysts for methanol dehydration to dimethyl ether (DME) in the MTD process (methanol-to-dimethyl ether).

  20. Synthesis of Pt/rGO catalysts with two different reducing agents and their methanol electrooxidation activity

    Energy Technology Data Exchange (ETDEWEB)

    Vu, Thu Ha Thi, E-mail: ptntd2004@yahoo.fr [Key Laboratory for Petrochemical and Refinery Technologies, 2 Pham Ngu Lao street, Hanoi (Viet Nam); Tran, Thanh Thuy Thi, E-mail: tranthithanhthuygl@gmail.com [Key Laboratory for Petrochemical and Refinery Technologies, 2 Pham Ngu Lao street, Hanoi (Viet Nam); Le, Hong Ngan Thi; Tran, Lien Thi; Nguyen, Phuong Hoa Thi; Nguyen, Minh Dang [Key Laboratory for Petrochemical and Refinery Technologies, 2 Pham Ngu Lao street, Hanoi (Viet Nam); Quynh, Bui Ngoc [Institut de recherches sur la catalyse et l’environnement de Lyon, UMR5256, 2 avenue Albert Einstein, 69626 Villeurbanne cedex (France)

    2016-01-15

    Highlights: • Pt/rGO catalysts were successfully synthesized using either NaBH{sub 4} or ethylene glycol. • Synthesis using NaBH{sub 4} could improve electrocatalytic towards methanol oxidation of Pt/rGO catalyst. • 40%Pt/rGO synthesized using NaBH{sub 4} showed the best electrocatalytic performance. - Abstract: The synthesis processes of Platinum (Pt) on reduced graphene oxide (rGO) catalysts from graphene oxide (GO) using two reducing agents including sodium borohydride and ethylene glycol is reported. Structure and morphology of Pt/rGO catalysts are characterized by X-ray powder diffraction, transmission electron microscopy, Raman spectroscopy, and X-ray photoelectron spectroscopy. Electrocatalytic methanol oxidation properties of these catalysts are evaluated by cyclic voltammetry and chronoamperometry. The results show that catalyst synthesized using sodium borohydride has a higher metallic Pt content and an improved catalytic performance in comparison to catalyst synthesized using ethylene glycol. Moreover, effect of Pt loading amount on electrocatalytic methanol oxidation performance of catalysts synthesized using sodium borohydride is systematically investigated. The optimal Pt loading amount on graphene is determined to be 40%.

  1. Low temperature synthesis and photoluminescent properties of CaMoO4:Eu3+ red phosphor with uniform micro-assemblies

    International Nuclear Information System (INIS)

    Yu, Fangyi; Zuo, Jian; Zhao, Zhi; Jiang, Chengying; Yang, Qing

    2011-01-01

    Highlights: → Synthesis of Eu 3+ -doped CaMoO 4 red phosphor via a facile hydrothermal method. → The morphology of the materials was manipulated using different alkaline sources. → Micro-structures were assembled by small nanostructures. → Luminescent investigations confirmed that the Eu 3+ ions have been effectively doped into the nanostructures. → Schematic diagram for the energy transfer clearly reveals the photoluminescent mechanism. -- Abstract: Scheelite-type Eu 3+ -doped CaMoO 4 red phosphor with uniform micro-assemblies has been successfully synthesized via a facile hydrothermal method at 120 o C for 10 h. The Eu 3+ -doped CaMoO 4 microstructures were assembled by small nanostructures and the morphology of materials was found to be manipulated by dropping different alkalis into the stock solution for the first time. The structure, morphology, and luminescent property were characterized and investigated by techniques of X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), transmission electron microscopy (TEM), high-resolution transmission electron microscopy (HRTEM), and photoluminescence (PL). The luminescent investigations confirmed that the Eu 3+ ions have been effectively doped into CaMoO 4 nanostructures. The successfully achieved Eu 3+ -doped CaMoO 4 nanostructures will be potential in technological applications on near UV chip-based white light emitting diode (WLED).

  2. Low-temperature thermal expansion

    International Nuclear Information System (INIS)

    Collings, E.W.

    1986-01-01

    This chapter discusses the thermal expansion of insulators and metals. Harmonicity and anharmonicity in thermal expansion are examined. The electronic, magnetic, an other contributions to low temperature thermal expansion are analyzed. The thermodynamics of the Debye isotropic continuum, the lattice-dynamical approach, and the thermal expansion of metals are discussed. Relative linear expansion at low temperatures is reviewed and further calculations of the electronic thermal expansion coefficient are given. Thermal expansions are given for Cu, Al and Ti. Phenomenologic thermodynamic relationships are also discussed

  3. Design of novel DME/methanol synthesis plants based on gasification of biomass

    DEFF Research Database (Denmark)

    Clausen, Lasse Røngaard

    -scale DME plants based on gasification of torrefied biomass. 2. Small-scale DME/methanol plants based on gasification of wood chips. 3. Alternative methanol plants based on electrolysis of water and gasification of biomass. The plants were modeled by using the component based thermodynamic modeling...... why the differences, in biomass to DME/methanol efficiency, between the small-scale and the large-scale plants, showed not to be greater, was the high cold gas efficiency of the gasifier used in the small-scale plants (93%). By integrating water electrolysis in a large-scale methanol plant, an almost...... large-scale DME plant) to 63%, due to the relatively inefficient electrolyser....

  4. Fatty acid methyl esters synthesis from non-edible vegetable oils using supercritical methanol and methyl tert-butyl ether

    International Nuclear Information System (INIS)

    Lamba, Neha; Modak, Jayant M.; Madras, Giridhar

    2017-01-01

    Highlights: • FAMEs were synthesized from non-edible oils using supercritical MeOH and MTBE. • Effect of time, temperature, pressure and molar ratio on conversions was studied. • Rate constants of reaction with methanol and MTBE differ by an order of magnitude. • Non-catalytic supercritical reactions are one order faster than acid catalyzed synthesis. - Abstract: Fatty acid methyl esters (FAMEs) are useful as biodiesel and have environmental benefits compared to conventional diesel. In this study, these esters were synthesized non-catalytically from non-edible vegetable oils: neem oil and mahua oil with two different methylating agents: methanol and methyl tert-butyl ether (MTBE). The effects of temperature, pressure, time and molar ratio on the conversion of triglycerides were studied. The temperature was varied in the range of 523–723 K with molar ratios upto 50:1 and a reaction time of upto 150 min. Conversion of neem and mahua oil to FAMEs with supercritical methanol was found to be 83% in 15 min and 99% in 10 min, respectively at 698 K. Further, a conversion of 46% of mahua oil and 59% of neem oil was obtained in 15 min at 723 K using supercritical MTBE. The rate constants evaluated using pseudo first order reaction kinetics were in the range of 4.7 × 10"−"6 to 1.0 × 10"−"3 s"−"1 for the investigated range of temperatures. The activation energies obtained were in the range of 62–113 kJ/mol for the reaction systems investigated. The supercritical synthesis was found to be superior to the catalytic synthesis of the corresponding FAMEs.

  5. Single-Step Syngas-to-Distillates (S2D) Synthesis via Methanol and Dimethyl Ether Intermediates: Final Report

    Energy Technology Data Exchange (ETDEWEB)

    Dagle, Robert A.; Lebarbier, Vanessa MC; Lizarazo Adarme, Jair A.; King, David L.; Zhu, Yunhua; Gray, Michel J.; Jones, Susanne B.; Biddy, Mary J.; Hallen, Richard T.; Wang, Yong; White, James F.; Holladay, Johnathan E.; Palo, Daniel R.

    2013-11-26

    The objective of the work was to enhance price-competitive, synthesis gas (syngas)-based production of transportation fuels that are directly compatible with the existing vehicle fleet (i.e., vehicles fueled by gasoline, diesel, jet fuel, etc.). To accomplish this, modifications to the traditional methanol-to-gasoline (MTG) process were investigated. In this study, we investigated direct conversion of syngas to distillates using methanol and dimethyl ether intermediates. For this application, a Pd/ZnO/Al2O3 (PdZnAl) catalyst previously developed for methanol steam reforming was evaluated. The PdZnAl catalyst was shown to be far superior to a conventional copper-based methanol catalyst when operated at relatively high temperatures (i.e., >300°C), which is necessary for MTG-type applications. Catalytic performance was evaluated through parametric studies. Process conditions such as temperature, pressure, gas-hour-space velocity, and syngas feed ratio (i.e., hydrogen:carbon monoxide) were investigated. PdZnAl catalyst formulation also was optimized to maximize conversion and selectivity to methanol and dimethyl ether while suppressing methane formation. Thus, a PdZn/Al2O3 catalyst optimized for methanol and dimethyl ether formation was developed through combined catalytic material and process parameter exploration. However, even after compositional optimization, a significant amount of undesirable carbon dioxide was produced (formed via the water-gas-shift reaction), and some degree of methane formation could not be completely avoided. Pd/ZnO/Al2O3 used in combination with ZSM-5 was investigated for direct syngas-to-distillates conversion. High conversion was achieved as thermodynamic constraints are alleviated when methanol and dimethyl are intermediates for hydrocarbon formation. When methanol and/or dimethyl ether are products formed separately, equilibrium restrictions occur. Thermodynamic relaxation also enables the use of lower operating pressures than what

  6. Facile synthesis of porous Pt-Pd nanospheres supported on reduced graphene oxide nanosheets for enhanced methanol electrooxidation

    Science.gov (United States)

    Li, Shan-Shan; Lv, Jing-Jing; Hu, Yuan-Yuan; Zheng, Jie-Ning; Chen, Jian-Rong; Wang, Ai-Jun; Feng, Jiu-Ju

    2014-02-01

    In this study, a simple, facile, and effective wet-chemical strategy was developed in the synthesis of uniform porous Pt-Pd nanospheres (Pt-Pd NSs) supported on reduced graphene oxide nanosheets (RGOs) under ambient temperature, where octylphenoxypolye thoxyethanol (NP-40) is used as a soft template, without any seed, organic solvent or special instruments. The as-prepared nanocomposites display enhanced electrocatalytic activity and good stability toward methanol oxidation, compared with commercial Pd/C and Pt/C catalysts. This strategy may open a new route to design and prepare advanced electrocatalysts for fuel cells.

  7. Ionothermal synthesis of β-NH4AlF4 and the determination by single crystal X-ray diffraction of its room temperature and low temperature phases

    International Nuclear Information System (INIS)

    Parnham, Emily R.; Slawin, Alex M.Z.; Morris, Russell E.

    2007-01-01

    β-NH 4 AlF 4 has been synthesised ionothermally using 1-ethyl-3-methylimidazolium hexafluorophosphate as solvent and template provider. β-NH 4 AlF 4 crystals were produced which were suitable for single crystal X-ray diffraction analysis. A phase transition occurs between room temperature (298 K) and low temperature (93 K) data collections. At 298 K the space group=I4/mcm (no. 140), α=11.642(5), c=12.661(5) A, Z=2 (10NH 4 AlF 4 ), wR(F 2 )=0.1278, R(F)=0.0453. At 93 K the space group=P4 2 /ncm (no. 138), α=11.616(3), c=12.677(3) A, Z=2 (10NH 4 AlF 4 ), wR(F 2 )=0.1387, R(F)=0.0443. The single crystal X-ray diffraction study of β-NH 4 AlF 4 shows the presence of two different polymorphs at low and room temperature, indicative of a phase transition. The [AlF 4/2 F 2 ] - layers are undisturbed except for a small tilting of the AlF 6 octahedra in the c-axis direction. -Ionothermal synthesis, the use of an ionic liquid as the solvent in materials preparation, has been used to prepare β-NH 4 AlF 4 , and structural characterisation indicates that there are two versions of the structure, a low temperature primitive phase at 93 K and a high temperature body-centered phase at 298 K

  8. Vol. 5: Low Temperature Physics

    International Nuclear Information System (INIS)

    Sitenko, A.

    1993-01-01

    Problems of modern physics and the situation with physical research in Ukraine are considered. Programme of the conference includes scientific and general problems. Its proceeding are published in 6 volumes. The papers presented in this volume refer to low-temperature physics

  9. Certification testing at low temperatures

    International Nuclear Information System (INIS)

    Noss, P.W.; Ammerman, D.J.

    2004-01-01

    Regulations governing the transport of radioactive materials require that most hypothetical accident condition tests or analyses consider the effects of the environmental temperature that most challenges package performance. For many packages, the most challenging temperature environment is the cold condition (-29 C according to U.S. regulations), primarily because the low temperature causes the highest free drop impact forces due to the higher strength of many energy-absorbing materials at this temperature. If it is decided to perform low temperature testing, it is only necessary that the relevant parts of the package have the required temperature prior to the drop. However, the details of performing a drop at low temperature can have a large influence on testing cost and technical effectiveness. The selection of the test site, the chamber and type of chilling equipment, instrumentation, and even the time of year are all important. Control of seemingly minor details such as the effect on internal pressure, placement of monitoring thermocouples, the thermal time constant of the test article, and icing of equipment are necessary to ensure a successful low temperature test. This paper will discuss these issues and offer suggestions based on recent experience

  10. Science with low temperature detectors

    International Nuclear Information System (INIS)

    Sadoulet, B.; Lawrence Berkeley National Lab., CA; California Univ., Berkeley

    1996-01-01

    The novel technique of particle detection with low temperature detectors opens a number of new scientific opportunities. We review some of these, focusing on three generic applications: far infrared bolometry taking as an example the cosmic microwave background, X-ray spectroscopy for astrophysics and biological applications, and massive calorimeters for dark matter searches and neutrino physics. (orig.)

  11. One-dimensional isothermal multicomponent diffusion-reaction model and its application to methanol synthesis over commercial Cu-based catalyst

    Directory of Open Access Journals (Sweden)

    Lei Kun

    2015-03-01

    Full Text Available The present work was a study on global reaction rate of methanol synthesis. We measured experimentally the global reaction rate in the internal recycle gradientless reactor over catalyst SC309. The diffusion-reaction model of methanol synthesis was suggested. For model we chose the hydrogenation of CO and CO2 as key reaction. CO and CO2 were key components in our model. The internal diffusion effectiveness factors of CO and CO2 in the catalyst were calculated by the numerical integration. A comparison with the experiment showed that all the absolute values of the relative error were less than 10%. The simulation results showed that decreasing reaction temperature and catalyst diameter were conducive to reduce the influence of the internal diffusion on the methanol synthesis.

  12. Direct synthesis of few-layer graphene supported platinum nanocatalyst for methanol oxidation

    Science.gov (United States)

    Tan, Hong; Ma, Xiaohui; Sheng, Leimei; An, Kang; Yu, Liming; Zhao, Hongbin; Xu, Jiaqiang; Ren, Wei; Zhao, Xinluo

    2014-11-01

    High-crystalline few-layer graphene supported Pt nanoparticles have been synthesized by arc discharge evaporation of carbon electrodes containing Pt element. A high-temperature treatment under hydrogen atmosphere has been carried out to obtain a new type of Pt/graphene catalyst for methanol oxidation in direct methanol fuel cell. The morphology and structure characterizations of as-grown few-layer graphene supported Pt nanoparticles and Pt/graphene catalysts have been studied by Raman spectroscopy, scanning electron microscopy with energy-dispersive spectroscopy, and high-resolution transmission electron microscopy. Cyclic voltammograms and chronoamperometric curves show that our present Pt/graphene catalysts have larger current density for methanol oxidation, higher tolerance to carbon monoxide poisoning, and better stability during the operating procedure, compared to commercial Pt/C catalysts.

  13. Adsorption and Deactivation Characteristics of Cu/ZnO-Based Catalysts for Methanol Synthesis from Carbon Dioxide

    Energy Technology Data Exchange (ETDEWEB)

    Natesakhawat, Sittichai; Ohodnicki, Paul R; Howard, Bret H; Lekse, Jonathan W; Baltrus, John P; Matranga, Christopher

    2013-07-09

    The adsorption and deactivation characteristics of coprecipitated Cu/ZnO-based catalysts were examined and correlated to their performance in methanol synthesis from CO₂ hydrogenation. The addition of Ga₂O₃ and Y₂O₃ promoters is shown to increase the Cu surface area and CO₂/H₂ adsorption capacities of the catalysts and enhance methanol synthesis activity. Infrared studies showed that CO₂ adsorbs spontaneously on these catalysts at room temperature as both monoand bi-dentate carbonate species. These weakly bound species desorb completely from the catalyst surface by 200 °C while other carbonate species persist up to 500 °C. Characterization using N₂O decomposition, X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), and transmission electron microscopy (TEM) with energy-dispersive X-ray spectroscopy (EDX) analysis clearly indicated that Cu sintering is the main cause of catalyst deactivation. Ga and Y promotion improves the catalyst stability by suppressing the agglomeration of Cu and ZnO particles under pretreatment and reaction conditions.

  14. Automatic low-temperature calorimeter

    International Nuclear Information System (INIS)

    Malyshev, V.M.; Mil'ner, G.A.; Shibakin, V.F.; Sorkin, E.L.

    1986-01-01

    This paper describes a low-temperature adiabatic calorimeter with a range of 1.5-500K. The system for maintaining adiabatic conditions is implemented by two resitance thermometers, whose sensitivity at low temperatures is several orders higher than that of thermocouples. The calorimeter cryostat is installed in an STG-40 portable Dewar flask. The calorimeter is controlled by an Elektronika-60 microcomputer. Standard platinum and germanium thermometers were placed inside of the calorimeter to calibrate the thermometers of the calorimeter and the shield, and the specific heats of specimens of OSCh 11-4 copper and KTP-8 paste were measured to demonstrate the possibilities of the described calorimeter. Experience with the calorimeter has shown that a thorough study of the dependence of heat capacity on temperature (over 100 points for one specimen) can be performed in one or two dats

  15. Ionomeric membranes based on partially sulfonated poly(styrene) : synthesis, proton conduction and methanol permeation

    NARCIS (Netherlands)

    Picchioni, F.; Tricoli, V.; Carretta, N.

    2000-01-01

    Homogeneuosly sulfonated poly(styrene) (SPS) was prepared with various concentration of sulfonic acid groups in the base polymer. Membranes cast from these materials were investigated in relation to proton conductivity and methanol permeability in the temperature range from 20°C to 60°C. It was

  16. Catalytic reactions of synthesis gas. Part 2. Methanol carbonylation and homologation

    Energy Technology Data Exchange (ETDEWEB)

    Niemelae, M.

    1993-01-01

    The aim of the review is to evaluate the applicability of methanol hydrocarbonylation as a second test reaction to study the nondissociative activation of CO by heterogeneous rhodium and cobalt catalysts. The main emphasis in methanol (hydro)carbonylation chemistry has been on homogeneous reactions. These systems have been seen advantageous in selectivity, activity and ease of modification. The heterogenization attempts have been carried out to obtain easier separation of the catalyst and the product. The activity of cobalt, rhodium and other metals supported on different materials have been studied in heterogeneous methanol (hydro)carbonylation. The observed activities have been considerably influenced by the support. The most effective catalyst support has been activated carbon. Good carbonylation activities and selectivities have also been observed in conjunction with zeolite supports. The literature study indicates that the typical experimental conditions of methanol (hydro)carbonylation do not exceed the constructional and operational limits of the available reactor system, i.e. 500 C and 50 bar. The reaction is suitable for testing Co and Rh precursors, since both cobalt and rhodium compounds have shown carbonylation activity.

  17. The kinetics of the methanol synthesis on a copper catalyst: An experimental study

    NARCIS (Netherlands)

    Bos, A.N.R.; Borman, P.C.; Kuczynski, M.; Westerterp, K.R.

    1989-01-01

    The kinetics of the low pressure of methanol from feed gases containing solely CO and H2 were studied in an internally recycled gradientless reactor. As experimental accuracy impeded the application of high CO contents, the experimental range of mole fraction of CO was limited to 0.04 to 0.22. The

  18. Ionomeric membranes based on partially sulfonated poly(styrene): synthesis, proton conduction and methanol permeation

    NARCIS (Netherlands)

    Carretta, N.; Tricoli, V.; Picchioni, F.

    2000-01-01

    Homogeneuosly sulfonated poly(styrene) (SPS) was prepared with various concentration of sulfonic acid groups in the base polymer. Membranes cast from these materials were investigated in relation to proton conductivity and methanol permeability in the temperature range from 20°C to 60°C. It was

  19. Thermoluminescent system for low temperatures

    International Nuclear Information System (INIS)

    Rosa, L.A.R. da; Caldas, L.V.E.; Leite, N.G.

    1988-09-01

    A system for measurements of the thermoluminescent glow curve, the thermoluminescent emission spectrum and the optical absorption spectrum of solid samples, from liquid nitrogen temperature up to 473 K, is reported. A specially designed temperature programmer provides a linear heating of the sample at a wide range of selectable heating rates, as also long term steady-state temperatures for annealing and isothermal decay studies. The system operates at a pressure of 1.33 x 10 -3 Pa. Presently it is being used for lithium fluoride low temperature thermoluminescent studies. (author) [pt

  20. Mechanical pumping at low temperature

    International Nuclear Information System (INIS)

    Perin, J.P.; Claudet, G.; Disdier, F.

    1995-01-01

    This novel concept consist of a mechanical pump able to run at low temperature (25K). Since gas density varies inversely with temperature, this pump would deliver much higher mass flow rate than at room temperature for a given size. Advantages of this concept are order of magnitude reduction in size, weight, when compared to a conventional pump scaled to perform the same mass flow rate at room temperature. This pump would be a solution to allow continuously tritium extraction and minimize the mass inventory. (orig.)

  1. Synthesis of Pt–Pd Bimetallic Porous Nanostructures as Electrocatalysts for the Methanol Oxidation Reaction

    Directory of Open Access Journals (Sweden)

    Yong Yang

    2018-03-01

    Full Text Available Pt-based bimetallic nanostructures have attracted a great deal of attention due to their unique nanostructures and excellent catalytic properties. In this study, we prepared porous Pt–Pd nanoparticles using an efficient, one-pot co-reduction process without using any templates or toxic reactants. In this process, Pt–Pd nanoparticles with different nanostructures were obtained by adjusting the temperature and ratio of the two precursors; and their catalytic properties for the oxidation of methanol were studied. The porous Pt–Pd nanostructures showed better electrocatalytic activity for the oxidation of methanol with a higher current density (0.67 mA/cm2, compared with the commercial Pt/C catalyst (0.31 mA/cm2. This method provides one easy pathway to economically prepare different alloy nanostructures for various applications.

  2. Synthesis of coin-like hollow carbon and performance as Pd catalyst support for methanol electrooxidation

    Energy Technology Data Exchange (ETDEWEB)

    Yuan, Dingsheng [Department of Chemistry and Institute of Nanochemistry, Jinan University, Guangzhou 510632 (China); State Key Laboratories of Optoelectronic Materials and Technologies, School of Physics and Engineering, Sun Yat-Sen University, Guangzhou 510275 (China); Xu, Changwei; Liu, Yingliang; Tan, Shaozao [Department of Chemistry and Institute of Nanochemistry, Jinan University, Guangzhou 510632 (China); Wang, Xin [School of Chemical and Biomedical Engineering, Nanyang Technological University, Singapore 639798 (Singapore); Wei, Zidong [School of Chemical Engineering, Chongqing University, Chongqing 400044 (China); Shen, Pei Kang [State Key Laboratories of Optoelectronic Materials and Technologies, School of Physics and Engineering, Sun Yat-Sen University, Guangzhou 510275 (China)

    2007-10-15

    The coin-like hollow carbon (CHC) has been synthesized by only using ethanol as the carbon source with a novel Mg/NiCl{sub 2} catalytic system via a facile solvothermal method for the first time. The CHC synthesized at optimized conditions shows an average thickness of less than 154 nm and the coin diameter of 1-3 {mu}m. The CHC is characterized by SEM, TEM, XRD and electrochemical techniques. Pd on CHC (denotes as Pd/CHC) electrocatalysts are prepared for methanol oxidation in alkaline media. The Pd/CHC electrocatalyst gives a mass activity of 2930 A g{sup -1} Pd for methanol oxidation against 870 A g{sup -1} Pd on Pd/C electrocatalyst. One main reason for the higher mass activity of the Pd/CHC is the higher electrochemical active surface area (EASA) of the Pd/CHC. (author)

  3. Wolte 5. low temperature electronics

    International Nuclear Information System (INIS)

    Balestra, F.; Dieudonne, F.; Jomaah, J.

    2002-01-01

    This book present the latest research and development results in advanced materials, technologies, devices, circuits and systems for low temperature electronics. The main themes of the papers are ranging from physics and fundamental aspects, modeling and simulation, to device and circuit design. The topics include advanced process and characterization, novel devices and cryogenic instrumentation. The papers are divided into nine sections, reflecting the main research efforts in different areas: i) deep submicron silicon MOSFETs, ii) alternative MOSFETs (SOI, innovating device architectures), iii) III-V devices, iv) other semiconductor devices (Ge devices, p-n junctions, IR sensors, semiconductor microcrystals), v) emerging devices and phenomena (nano Si-based devices, conduction and fluctuations mechanisms), vi) superconducting materials, vii) superconducting detectors, viii) superconducting devices and circuits (RSFQ, SIS mixers, metal-superconducting-semiconductor structures), ix) low temperature electronics for space applications. Six invited papers presented by internationally recognized authors, and 39 contributed papers are presented. The invited papers provide an excellent overview of today's status and progress, as well as tomorrow's challenges and trends in this important discipline for many cryogenic applications. (authors)

  4. CFD Simulation of Dimethyl Ether Synthesis from Methanol in an Adiabatic Fixed-bed Reactor

    Directory of Open Access Journals (Sweden)

    Mohammad Golshadi

    2013-04-01

    Full Text Available A computational fluid dynamic (CFD study of methanol (MeOH to dimethyl ether (DME process in an adiabatic fixed-bed reactor is presented. One of the methods of industrial DME production is the catalytic dehydration of MeOH. Kinetic model was derived based on Bercic rate. The parameters of this equation for a specific catalyst were tuned by solving a one-dimensional homogenous model using MATLAB optimization module. A two-dimensional CFD simulation of the reaction is demonstrated and considered as numerical experiments. A sensitivity analysis was run in order to find the effect of temperature, pressure, and WHSV on the reactor performance. Good agreement was achieved between bench experimental data and the model. The results show that the maximum conversion of reaction (about 85.03% is obtained at WHSV=10 h-1 and T=563.15 K, whereas the inlet temperature has a greater effect on methanol conversion. Moreover, the effect of water in inlet feed on methanol conversion is quantitatively studied. It was concluded that the results obtained from CFD analysis give precise guidelines for further studies on the optimization of reactor performance.

  5. Mixed phase Pt-Ru catalyst for direct methanol fuel cell anode by flame aerosol synthesis

    DEFF Research Database (Denmark)

    Chakraborty, Debasish; Bischoff, H.; Chorkendorff, Ib

    2005-01-01

    A spray-flame aerosol catalyzation technique was studied for producing Pt-Ru anode electrodes for the direct methanol fuel cell. Catalysts were produced as aerosol nanoparticles in a spray-flame reactor and deposited directly as a thin layer on the gas diffusion layer. The as-prepared catalyst wa......Ru1/Vulcan carbon. The kinetics of methanol oxidation on the mixed phase catalyst was also explored by electrochemical impedance spectroscopy. (c) 2005 The Electrochemical Society.......A spray-flame aerosol catalyzation technique was studied for producing Pt-Ru anode electrodes for the direct methanol fuel cell. Catalysts were produced as aerosol nanoparticles in a spray-flame reactor and deposited directly as a thin layer on the gas diffusion layer. The as-prepared catalyst...... was found to be a mixture of nanocrystalline, mostly unalloyed Pt and an amorphous phase mostly of Ru and to a lesser extent of Pt oxides on top of the crystalline phase. The flame-produced Pt1Ru1 demonstrated similar onset potential but similar to 60% higher activity compared to commercially available Pt1...

  6. Synthesis of dimethyl carbonate (DMC) by oxidative carbonylation of methanol using polymer-supported CuCl{sub 2} catalyst

    Energy Technology Data Exchange (ETDEWEB)

    Sato, Y. [Daicel Chemical Industries, Ltd., Hyogo (Japan). Research Center; Kobe University, Kobe (Japan); Kagotani, M. [Daicel Chemical Industries, Ltd., Hyogo (Japan). Research Center; Soma, Y. [Osaka National Research Institute, Osaka (Japan)

    2000-01-01

    Polymer, including 2,2'-bipyridine, poly(4-methyl-4'-vinyl-2,2'-bipyridine)(Pvbpy), was investigated for the synthesis of dimethyl carbonate (DMC) as a support for CuCl{sub 2}, by oxidative carbonylation of methanol in the liquid-phase. The CuCl{sub 2} complex (Pvbpy-CuCl{sub 2}) was insoluble in methanol, and the reaction system was heterogeneous. The Pvbpy-CuCl{sub 2} catalyst showed considerable catalytic activity (DMC yield: 44.4 % and DMC selectivity: 9206 %, at methanol conversion: 1.79 %), which is comparable to the previously reported data of poly (vinylpyridine) (PVP)-CuCl{sub 2} catalyst; the Pvbpy-CuCl{sub 2} catalyst could be recycled after filtration and washing thrice, provided, not having lost activity. The corrosion originating from Cl{sup -} was greatly improved by immobilizing the CuCl{sub 2} by Pvbpy. Elimination of CuCl{sub 2} from the Pvbpy support was observed during the reaction. In the first reaction, about 38 % of the initially supported Cl was released, and in the second and the third reactions, most of the Cl was retained. The rate of corrosion of stainless steels in the first use of the catalyst (0.6 mg h{sup -1} for HC276) was greater than that in the rate of the second and the third uses (<0.1 mg h{sup -1}). These results are closely related to the amount of Cl{sup -} released from the Pvbpy support, which demonstrates that the main cause of corrosion in the catalytic system is Cl{sup -} released from the Pvbpy-CuCl{sub 2} catalyst. From XPS study of the catalyst, it became obvious that Cu(2) was gradually reduced to Cu(1) during the reaction. (author)

  7. On-line methanol sensor system development for recombinant ...

    African Journals Online (AJOL)

    On-line methanol sensor system development for recombinant human serum ... of the methanol sensor system was done in a medium environment with yeast cells ... induction at a low temperature and a pH where protease does not function.

  8. A facile approach to the synthesis of highly electroactive Pt nanoparticles on graphene as an anode catalyst for direct methanol fuel cells.

    Science.gov (United States)

    Zhou, Yi-Ge; Chen, Jing-Jing; Wang, Feng-bin; Sheng, Zhen-Huan; Xia, Xing-Hua

    2010-08-28

    A one-step electrochemical approach to the synthesis of highly dispersed Pt nanoparticles on graphene has been proposed. The resultant Pt NPs@G nanocomposite shows higher electrocatalytic activity and long-term stability towards methanol electrooxidation than the Pt NPs@Vulcan.

  9. Design of adiabatic fixed-bed reactors for the partial oxidation of methane to synthesis gas. Application to production of methanol and hydrogen-for-fuel-cells

    NARCIS (Netherlands)

    Smet, de C.R.H.; Croon, de M.H.J.M.; Berger, R.J.; Marin, G.B.M.M.; Schouten, J.C.

    2001-01-01

    Adiabatic fixed-bed reactors for the catalytic partial oxidn. (CPO) of methane to synthesis gas were designed at conditions suitable for the prodn. of methanol and hydrogen-for-fuel-cells. A steady-state, one-dimensional heterogeneous reactor model was applied in the simulations. Intra-particle

  10. Towards ‘greener’ catalyst manufacture: Reduction of wastewater from the preparation of Cu/ZnO/Al2O3 methanol synthesis catalysts

    NARCIS (Netherlands)

    Prieto, G.; de Jong, K.P.; de Jongh, P.E.

    2013-01-01

    The generation of large volumes of nitrate-containing wastewater is a major issue in the industrial production of solid catalysts such as Cu/ZnO/Al2O3 employed in methanol synthesis. Extensive washing with water is needed to remove nitrate (and sodium) residues in the as-precipitated metal

  11. Controlled synthesis of Pt/CS/PW12-GNs composite as an anodic electrocatalyst for direct methanol fuel cells

    International Nuclear Information System (INIS)

    Li, Zhongshui; Lei, Fengling; Ye, Lingting; Zhang, Xiaofeng; Lin, Shen

    2015-01-01

    Controlled assembly in aqueous solution was used to synthesize the well-organized Pt/CS/PW 12 -GNs composite. By the aid of linear cationic polysaccharide chitosan, 2-D distribution worm-like Pt nanoparticles with their length and width of 15–20 and 3–4 nm, respectively, were formed on the surface of CS/PW 12 -GNs using HCOOH as a reducing agent at room temperature. The introduction of CS leads to well dispersion of worm-like Pt nanoparticles, the electroactivity of H 3 PW 12 O 40 (PW 12 ) alleviates CO poisoning toward Pt particles, and graphene nanosheets (GNs) ensure excellent electrical conductivity of the composites. The combined action among different components results in significantly enhanced catalytic activity of Pt/CS/PW 12 -GNs toward methanol oxidation and better tolerance of CO. The as-synthesized Pt/CS/PW 12 -GNs exhibit the forward peak current density of 445 mA mg −1 , which is much higher than that (220 mA mg −1 ) for Pt/C-JM (the commercially available Johnson Matthey Hispec4000 catalyst, simplified as Pt/C-JM) and some recently reported Pt/graphene-based nanomaterials. The construction of 2-D distribution worm-like Pt nanoparticles and facile wet chemical synthesis strategy provide a promising way to develop superior performance electrocatalysts for direct methanol fuel cells applications

  12. Controlled synthesis of Pt/CS/PW{sub 12}-GNs composite as an anodic electrocatalyst for direct methanol fuel cells

    Energy Technology Data Exchange (ETDEWEB)

    Li, Zhongshui; Lei, Fengling; Ye, Lingting; Zhang, Xiaofeng; Lin, Shen, E-mail: shenlin@fjnu.edu.cn [Fujian Normal University, College of Chemistry & Chemical Engineering (China)

    2015-04-15

    Controlled assembly in aqueous solution was used to synthesize the well-organized Pt/CS/PW{sub 12}-GNs composite. By the aid of linear cationic polysaccharide chitosan, 2-D distribution worm-like Pt nanoparticles with their length and width of 15–20 and 3–4 nm, respectively, were formed on the surface of CS/PW{sub 12}-GNs using HCOOH as a reducing agent at room temperature. The introduction of CS leads to well dispersion of worm-like Pt nanoparticles, the electroactivity of H{sub 3}PW{sub 12}O{sub 40} (PW{sub 12}) alleviates CO poisoning toward Pt particles, and graphene nanosheets (GNs) ensure excellent electrical conductivity of the composites. The combined action among different components results in significantly enhanced catalytic activity of Pt/CS/PW{sub 12}-GNs toward methanol oxidation and better tolerance of CO. The as-synthesized Pt/CS/PW{sub 12}-GNs exhibit the forward peak current density of 445 mA mg{sup −1}, which is much higher than that (220 mA mg{sup −1}) for Pt/C-JM (the commercially available Johnson Matthey Hispec4000 catalyst, simplified as Pt/C-JM) and some recently reported Pt/graphene-based nanomaterials. The construction of 2-D distribution worm-like Pt nanoparticles and facile wet chemical synthesis strategy provide a promising way to develop superior performance electrocatalysts for direct methanol fuel cells applications.

  13. A green chemistry approach for the synthesis and characterization of bioactive gold nanoparticles using Azolla microphylla methanol extract

    Science.gov (United States)

    Kunjiappan, Selvaraj; Chowdhury, Ranjana; Bhattacharjee, Chiranjib

    2014-06-01

    This article reports the environmentally benign synthesis of gold nanoparticles (GNPs) using methanol extract of Azolla microphylla as the stabilizing and reducing agent. The GNPs were characterized by UV-vis spectrophotometry and FTIR, and the morphological characteristics were analyzed by XRD, FESEM-EDX and HRTEM. The GNPs could be formed in very short time, even in less than 30 min. The nanoparticles measured by UV-spectrophotometer demonstrated a peak at 540 nm corresponding to surface plasmon resonance spectra, and the peaks showed by FTIR suggested the presence of organic biomolecules on the surface of the GNPs. XRD results confirmed the crystalline nature of the GNPs, and FESEM-EDX and HRTEM analyses had been performed in the size ranges of 17-40 nm and 1.25-17.5 nm respectively. The synthesized GNPs showed excellent antioxidant activity. This study shows the feasibility of using plant sources for the biosynthesis of GNPs.

  14. The Low temperature CFB gasifier

    DEFF Research Database (Denmark)

    Stoholm, P.; Nielsen, Rasmus Glar; Fock, Martin W.

    2003-01-01

    %) particle separation by the hot secondary cyclone. The next LT-CFB experiment, currently under preparation, is expected to be on either municipal/industrial waste or animal manure. Eventually a 500 kW LT-CFB test plant scheduled for commission during summer 2003, and the anticipated primary LT......The Low Temperature Circulating Fluidised Bed (LT-CFB) gasification process aims at avoiding problems due to ash deposition and agglomeration when using difficult fuels such as agricultural biomass and many waste materials. This, as well as very simple gas cleaning, is achieved by pyrolysing...... the fuel at around 650?C in a CFB reaction chamber and subsequently gasifying the char at around 730oC in a slowly fluidised bubbling bed chamber located in the CFB particle recirculation path. In this paper the novel LT-CFB concept is further described together with the latest test results from the 50 k...

  15. Low Temperature Hydrogen Antihydrogen Interactions

    International Nuclear Information System (INIS)

    Armour, E. A. G.; Chamberlain, C. W.

    2001-01-01

    In view of current interest in the trapping of antihydrogen (H-bar) atoms at low temperatures, we have carried out a full four-body variational calculation to determine s-wave elastic phase shifts for hydrogen antihydrogen scattering, using the Kohn Variational Principle. Terms outside the Born-Oppenheimer approximation have been taken into account using the formalism of Kolos and Wolniewicz. As far as we are aware, this is the first time that these terms have been included in an H H-bar scattering calculation. This is a continuation of earlier work on H-H-bar interactions. Preliminary results differ substantially from those calculated using the Born-Oppenheimer approximation. A method is outlined for reducing this discrepancy and taking the rearrangement channel into account.

  16. Mechanical pumping at low temperature

    Energy Technology Data Exchange (ETDEWEB)

    Perin, J.P.; Claudet, G.; Disdier, F.

    1994-12-31

    This new concept consists of a mechanical pump able to run at low temperature (25 K). Since gas density varies inversely with temperature, the pump could deliver much higher mass flow rate than at room temperature for a given size. Advantages of this concept are reduction of an order of magnitude in size and weight when compared to a conventional pump scaled to perform the same mass flow rate at room temperature. Results obtained at 80 K and 25 K with a Holweck type molecular drag pump of 100 mm diameter and with few stages of a turbomolecular pump running at the same temperatures, are given. This pump would be a solution to allow continuous tritium extraction and minimize the mass inventory for the ITER (International Tokamak Experiment Reactor). 5 figs., 2 tabs., 4 refs.

  17. Low-temperature magnetic modification of sensitive biological materials

    Czech Academy of Sciences Publication Activity Database

    Pospišková, K.; Šafařík, Ivo

    2015-01-01

    Roč. 142, mar (2015), s. 184-188 ISSN 0167-577X R&D Projects: GA MŠk(CZ) LD13021 Institutional support: RVO:67179843 Keywords : magnetic iron oxides particles * microwave-assisted synthesis * low-temperature magnetic modification * immobilized enzymes Subject RIV: BO - Biophysics Impact factor: 2.437, year: 2015

  18. Synthesis of monodisperse palladium nanocubes and their catalytic activity for methanol electrooxidation

    International Nuclear Information System (INIS)

    Hao, Ding; Xue-Zhao, Shi; Cheng-Min, Shen; Chao, Hui; Zhi-Chuan, Xu; Chen, Li; Yuan, Tian; Deng-Ke, Wang; Hong-Jun, Gao

    2010-01-01

    The single crystalline palladium nanocubes with an average size of 7 nm were prepared in the presence of poly (vinyl pyrrolidone) (PVP) and KBr using the polyol method. The as-prepared Pd nanocubes were highly uniform in both size and shape. The ordered packing structures including monolayer and multilayer can be fabricated via the rate-controlled evaporation of solution solvent. The electrochemical catalytic activity of these Pd nanocubes towards methanol oxidation was found to be higher than that of spherical Pd nanoparticles of similar size. (condensed matter: structure, thermal and mechanical properties)

  19. Synthesis of monodisperse palladium nanocubes and their catalytic activity for methanol electrooxidation

    Science.gov (United States)

    Ding, Hao; Shi, Xue-Zhao; Shen, Cheng-Min; Hui, Chao; Xu, Zhi-Chuan; Li, Chen; Tian, Yuan; Wang, Deng-Ke; Gao, Hong-Jun

    2010-10-01

    The single crystalline palladium nanocubes with an average size of 7 nm were prepared in the presence of poly (vinyl pyrrolidone) (PVP) and KBr using the polyol method. The as-prepared Pd nanocubes were highly uniform in both size and shape. The ordered packing structures including monolayer and multilayer can be fabricated via the rate-controlled evaporation of solution solvent. The electrochemical catalytic activity of these Pd nanocubes towards methanol oxidation was found to be higher than that of spherical Pd nanoparticles of similar size.

  20. Theoretical study of methanol synthesis from CO2 and CO hydrogenation on the surface of ZrO2 supported In2O3 catalyst

    Science.gov (United States)

    Dou, Maobin; Zhang, Minhua; Chen, Yifei; Yu, Yingzhe

    2018-06-01

    The interactions between ZrO2 support and In2O3 catalyst play pivotal role in the catalytic conversion of CO2 to methanol. Herein, a density functional theory study has been conducted to research the mechanism of methanol synthesis from CO2 and CO hydrogenation on the defective ZrO2 supported In2O3(110) surface (D surface). The calculations reveal that methanol is produced mainly via the HCOO reaction pathway from CO2 hydrogenation on D surface, and the hydrogenation of HCOO to form H2COO species with an activation barrier of 1.21 eV plays the rate determining step for the HCOO reaction pathway. The direct dissociation of CO2 to CO on D surface is kinetically and energetically prohibited. Methanol synthesis from CO hydrogenation on D surface is much facile comparing with the elementary steps involved in CO2 hydrogenation. The rate determining step of CO hydrogenation to methanol is the formation of H3CO species on the vacancy site with a barrier of 0.51 eV. ZrO2 support has significant effect on the suppressing of the dissociation of CO2 and stabilization of H2COO species on the surface of In2O3 catalyst.

  1. Synthesis of carbon-supported copper catalyst and its catalytic performance in methanol dehydrogenation

    Energy Technology Data Exchange (ETDEWEB)

    Shelepova, Ekaterina V. [Boreskov Institute of Catalysis SB RAS, pr. Ac. Lavrentieva, 5, Novosibirsk, 630090 (Russian Federation); National Research Tomsk Polytechnic University, Lenin av., 30, Tomsk, 634050 (Russian Federation); Vedyagin, Aleksey A., E-mail: vedyagin@catalysis.ru [Boreskov Institute of Catalysis SB RAS, pr. Ac. Lavrentieva, 5, Novosibirsk, 630090 (Russian Federation); National Research Tomsk Polytechnic University, Lenin av., 30, Tomsk, 634050 (Russian Federation); Ilina, Ludmila Yu.; Nizovskii, Alexander I. [Boreskov Institute of Catalysis SB RAS, pr. Ac. Lavrentieva, 5, Novosibirsk, 630090 (Russian Federation); Tsyrulnikov, Pavel G. [Institute of Hydrocarbon Processing SB RAS, Neftezavodskaya st., 54, Omsk, 644040 (Russian Federation)

    2017-07-01

    Highlights: • Carbon-supported copper catalyst was studied in dehydrogenation of methanol. • Reduction temperature affected size of Cu particles and Cu{sup 0}/Cu{sup 2+} ratio. • Reduction at 400 °C was required to obtain high methyl formate yield. - Abstract: Carbon-supported copper catalyst was prepared by incipient wetness impregnation of Sibunit with an aqueous solution of copper nitrate. Copper loading was 5 wt.%. Temperature of reductive pretreatment was varied within a range of 200–400 °C. The samples were characterized by transmission electron microscopy, X-ray diffraction analysis, X-ray photoelectron and X-ray absorption spectroscopies. Catalytic activity of the samples was studied in a reaction of methanol dehydrogenation. Silica-based catalyst with similar copper loading was used as a reference. It was found that copper is distributed over the surface of support in the form of metallic and partially oxidized particles of about 12–17 nm in size. Diminished interaction of copper with support was supposed to be responsible for high catalytic activity.

  2. Synthesis and Characterization of Electrodeposited C-PANI-Pd-Ni Composite Electrocatalyst for Methanol Oxidation

    Directory of Open Access Journals (Sweden)

    S. S. Mahapatra

    2014-01-01

    Full Text Available Electropolymerization of aniline at the graphite electrodes was achieved by potentiodynamic method. Electrodeposition of Pd (C-PANI-Pd and Ni (C-PANI-Ni and codeposition of Pd-Ni (C-PANI-Pd-Ni microparticles into the polyaniline (PANI film coated graphite (C-PANI were carried out under galvanostatic control. The morphology and composition of the composite electrodes were obtained using scanning electron microscopy (SEM and energy dispersive X-ray analysis (EDX techniques. The electrochemical behavior and electrocatalytic activity of the electrode were characterized using cyclic voltammetry (CV, electrochemical impedance spectroscopy (EIS, and chronoamperometric (CA methods in acidic medium. The C-PANI-Pd-Ni electrode showed an improved catalytic performance towards methanol oxidation in terms of lower onset potential, higher anodic oxidation current, greater stability, lower activation energy, and lower charge transfer resistance. The enhanced electrocatalytic activity might be due to the greater permeability of C-PANI films for methanol molecules, better dispersion of Pd-Ni microparticles into the polymer matrixes, and the synergistic effects between the dispersed metal particles and their matrixes.

  3. Nanocomposite for methanol oxidation: synthesis and characterization of cubic Pt nanoparticles on graphene sheets

    Directory of Open Access Journals (Sweden)

    Tung-Yuan Yung, Jer-Yeu Lee and Ling-Kang Liu

    2013-01-01

    Full Text Available We present our recent results on Pt nanoparticles on graphene sheets (Pt-NPs/G, a nanocomposite prepared with microwave assistance in ionic liquid 2-hydroxyethanaminiumformate. Preparation of Pt-NPs/G was achieved without the addition of extra reductant such as hydrazine or ethylene glycol. The Pt nanoparticles on graphene have a cubic-like shape (about 60 wt% Pt loading, Pt-NPs/G and the particle size is 6 ± 3 nm from transmission electron microscopy results. Electrochemical cyclic voltammetry studies in 0.5 M aqueous H2SO4 were performed using Pt-NPs/G and separately, for comparison, using a commercially available electrocatalyst (60 wt% Pt loading, Pt/C. The electrochemical surface ratio of Pt-NPs/G to Pt/C is 0.745. The results of a methanol oxidation reaction (MOR in 0.5 M aqueous H2SO4 + 1.0 M methanol for the two samples are presented. The MOR results show that the ratios of the current density of oxidation (If to the current density of reduction (Ib are 3.49 (Pt-NPs/G and 1.37 (Pt/C, respectively, with a preference by 2.55 times favoring Pt-NPs/G. That is, the tolerance CO poisoning of Pt-NPs/G is better than that of commercial Pt/C.

  4. Synthesis and Activity Test of Cu/ZnO/Al2O3 for the Methanol Steam Reforming as a Fuel Cell’s Hydrogen Supplier

    Directory of Open Access Journals (Sweden)

    IGBN Makertihartha

    2009-05-01

    Full Text Available The synthesis of hydrogen from hydrocarbons through the steam reforming of methanol on Cu/ZnO/Al2O3 catalyst has been investigated. This process is assigned to be one of the promising alternatives for fuel cell hydrogen process source. Hydrogen synthesis from methanol can be carried out by means of methanol steam reforming which is a gas phase catalytic reaction between methanol and water. In this research, the Cu/ZnO/Al2O3 catalyst prepared by the dry impregnation was used. The specific surface area of catalyst was 194.69 m2/gram.The methanol steam reforming (SRM reaction was carried out by means of the injection of gas mixture containing methanol and water with 1:1.2 mol ratio and 20-90 mL/minute feed flow rate to a fixed bed reactor loaded by 1 g of catalyst. The reaction temperature was 200-300 °C, and the reactor pressure was 1 atm. Preceding the reaction, catalyst was reduced in the H2/N2 mixture at 160 °C. This study shows that at 300 °C reaction temperature, methanol conversion reached 100% at 28 mL/minute gas flow rate. This conversion decreased significantly with the increase of gas flow rate. Meanwhile, the catalyst prepared for SRM was stable in 36 hours of operation at 260 °C. The catalyst exhibited a good stability although the reaction condition was shifted to a higher gas flow rate.

  5. The Low Temperature Microgravity Physics Facility Project

    Science.gov (United States)

    Chui, T.; Holmes, W.; Lai, A.; Croonquist, A.; Eraker, J.; Abbott, R.; Mills, G.; Mohl, J.; Craig, J.; Balachandra, B.; hide

    2000-01-01

    We describe the design and development of the Low Temperature Microgravity Physics Facility, which is intended to provide a unique environment of low temperature and microgravity for the scientists to perform breakthrough investigations on board the International Space Station.

  6. The Low Temperature CFB Gasifier

    DEFF Research Database (Denmark)

    Stoholm, P.; Nielsen, Rasmus Glar; Richardt, K.

    2004-01-01

    straw, animal manure and waste and for co-firing the product gas in existing, e.g. coal fired power plant boilers. The aim is to prevent fouling, agglomeration and high temperature corrosion caused by potassium and chlorine and other fuel components when producing electricity. So far 92 hours......The Low Temperature Circulating Fluidised Bed (LT-CFB) gasification process is described together with the 50 kW and the 500 kW test plants and latest test results. The LT-CFB process is especially developed for medium and large scale (few to >100 MW) gasification of problematic bio-fuels like...... of experiments with the 50 kW test plant with two extremely difficult types of straw has shown low char losses and high retentions of ash including e.g. potassium. Latest 27 hours of experiments with dried, high ash pig- and hen manure has further indicated the concepts high fuel flexibility. The new 500 kW test...

  7. Low-temperature nuclear orientation

    International Nuclear Information System (INIS)

    Stone, N.J.; Postma, H.

    1986-01-01

    This book comprehensively surveys the many aspects of the low temperature nuclear orientation method. The angular distribution of radioactive emissions from nuclei oriented by hyperfine interactions in solids, is treated experimentally and theoretically. A general introductory chapter is followed by formal development of the theory of the orientation process and the anisotropic emission of decay products from oriented nuclei, applied to radioactive decay and to reactions. Five chapters on applications to nuclear physics cover experimental studies of alpha, beta and gamma emission, nuclear moment measurement and level structure information. Nuclear orientation studies of parity non-conservation and time reversal asymmetry are fully described. Seven chapters cover aspects of hyperfine interactions, magnetic and electric, in metals, alloys and insulating crystals, including ordered systems. Relaxation phenomena and the combined technique of NMR detection using oriented nuclei are treated at length. Chapters on the major recent development of on-line facilities, giving access to short lived nuclei far from stability, on the use of nuclear orientation for thermometry below 1 Kelvin and on technical aspects of the method complete the main text. Extensive appendices, table of relevant parameters and over 1000 references are included to assist the design of future experiments. (Auth.)

  8. The role of various fuels on microwave-enhanced combustion synthesis of CuO/ZnO/Al2O3 nanocatalyst used in hydrogen production via methanol steam reforming

    International Nuclear Information System (INIS)

    Ajamein, Hossein; Haghighi, Mohammad; Alaei, Shervin

    2017-01-01

    Graphical abstract: CuO/ZnO/Al 2 O 3 nanocatalysts were synthesized by the fast and simple microwave enhanced combustion method. Considering that the fuel type is one of the effective parameters on quality of the prepared nanocatalysts, different fuels such as sorbitol, propylene glycol, glycerol, diethylene glycol and ethylene glycol were used. XRD, FESEM, FTIR, EDX, and BET analyses were applied to determine the physicochemical properties of fabricated nanocatalysts. The catalytic experiments were performed in a fixed bed reactor in the temperature range of 160–300 °C. The characteristic and reactivity properties of fabricated nanocatalysts proved that ethylene glycol is the suitable fuel for preparation of CuO/ZnO/Al 2 O 3 nanocatalysts via microwave enhanced combustion method. - Highlights: • Microwave combustion synthesis of CuO/ZnO/Al 2 O 3 nanocatalysts by different fuels. • Enhancement of methanol conversion at low temperatures by selecting proper fuel. • Providing a large number of combustion pores by application of ethylene glycol as fuel. • Increase of CO selectivity in steam methanol reforming by Zn(0 0 2) crystallite facet. - Abstract: A series of CuO/ZnO/Al 2 O 3 nanocatalysts were synthesized by the microwave enhanced combustion method to evaluate the influence of fuel type. Sorbitol, propylene glycol, glycerol, diethylene glycol and ethylene glycol were used as fuel. XRD results revealed that application of ethylene glycol led to highly dispersed CuO and ZnO crystals. It was more highlighted about Cu(1 1 1) crystallite facet which known as the main active site of methanol steam reforming. Moreover, using ethylene glycol resulted homogeneous morphology and narrow particles size distribution (average surface particle size is about 265 nm). Due to the significant physicochemical properties, the catalytic experiments showed that the sample prepared by ethylene glycol achieved total conversion of methanol at 260 °C. Its carbon monoxide

  9. Unified modeling and feasibility study of novel green pathway of biomass to methanol/dimethylether

    International Nuclear Information System (INIS)

    Ravaghi-Ardebili, Zohreh; Manenti, Flavio

    2015-01-01

    Graphical abstract: Biomass-to-methanol/DME synthesis process layout. - Highlights: • Design, simulation, and control of the direct-storage concentrating solar plant. • Feasibility study of the low-temperature biomass gasification. • First-principles model of biomass gasifier. • First-principles model of one-step methanol/dimethylether synthesis reactor. • Integrated numerical platform for total plant simulation. - Abstract: A novel, integrated and unified process is proposed, modeled and studied for converting biomass to methanol (MeOH)/dimethylether (DME) to demonstrate its feasibility and applicability for the global industrial sector. The unified process consists of a concentrating solar power (CSP) plant, which supplies the produced steam to the biomass gasification process as well as to the downstream conversions to chemical commodities and energy carriers. To preserve the effectiveness of the biomass gasification with low-temperature solar-powered generated steam (approximately 400–410 °C), the gasification process is studied by means of a multi-complex (multi-scale, multi-phase, and multi-component) model and adapted to the novel proposed conditions. The syngas generated in the biomass gasification unit is then converted into MeOH/DME by means of one-step synthesis technology to improve the overall yield of the biomass-to-methanol process

  10. Zeolite synthesis from the pyrrolidine containing system and their catalytic properties in the methanol conversion reaction

    Energy Technology Data Exchange (ETDEWEB)

    Suzuki, Kunio; Kiyozumi, Yoshimichi; Shin, Shigemitsu; Ogawa, Kiyoshi; Yamazaki, Yasuyoshi; Watanabe, Hideo

    1987-12-18

    Systhesis of zeolite from a system containing cheaper pyrrolidine as a crystallization regulator than quaternary ammonium ion was carried out and the methanol conversion reaction was studied over the systhesized zeolite to get C/sub 2/ and C/sub 3/ olefins. Hydrous gels were prepared by adding and agitating pyrrolidine, water glass and sulfuric acid to aluminum sulfate solution; and aluminum nitrate, colloidal silica and pyrrolidine to NaOH solution. Five zeolite, that is, ZSM-5, ZSM-35, ZSM-39, ZSM-48 and KZ-1 were synthesized by changing gel components. X-ray powder diffraction, BET specific surface areas, micropore diameters, micropore volumes, oxygen contents by scanning electron photomicrographs and infra-red spectra were examined. The organic base in hydrous gels influenced greatly on the zeolite composition and structure. The ZSM-5 zeolite exhibited the superior performance as to a high selectivity of light olefins over the target of development. (12 figs, 1 tab, 20 refs)

  11. Intermetallic compounds of Ni and Ga as catalysts for the synthesis of methanol

    DEFF Research Database (Denmark)

    Sharafutdinov, Irek; Elkjær, Christian Fink; de Carvalho, Hudson Wallace Pereira

    2014-01-01

    In this work, we present a detailed study of the formation of supported intermetallic Ni–Ga catalysts for CO2 hydrogenation to methanol. The bimetallic phase is formed during a temperature-programmed reduction of the metal nitrates. By utilizing a combination of characterization techniques......, in particular in situ and ex situ X-ray diffraction, in situ X-ray absorption spectroscopy, transmission electron microscopy combined with electron energy loss spectroscopy and X-ray fluorescence, we have studied the formation of intermetallic Ni–Ga catalysts of two compositions: NiGa and Ni5Ga3. These methods...... demonstrate that the catalysts with the desired intermetallic phase and composition are formed upon reduction in hydrogen and enable us to propose a mechanism of the Ni–Ga nanoparticles formation. By studying the effect of calcination prior to catalyst reduction, we show that the reactivity depends...

  12. A microkinetic model of the methanol oxidation over silver

    DEFF Research Database (Denmark)

    Andreasen, A.; Lynggaard, H.; Stegelmann, C.

    2003-01-01

    A simple microkinetic model for the oxidation of methanol on silver based on surface science studies at UHV and low temperatures has been formulated. The reaction mechanism is a simple Langmuir-Hinshelwood mechanism, with one type of active oxygen and one route to formaldehyde and carbon dioxide......, respectively. The model explains observed reaction orders, selectivity, apparent activation enthalpies and the choice of industrial reaction conditions. More interesting the model disproves the notion that the mechanism deduced from surface science in UHV cannot be responsible for formaldehyde synthesis...

  13. LOW TEMPERATURE CATHODE SUPPORTED ELECTROLYTES

    Energy Technology Data Exchange (ETDEWEB)

    Harlan U. Anderson

    2000-03-31

    This project has three main goals: Thin Films Studies, Preparation of Graded Porous Substrates and Basic Electrical Characterization and Testing of Planar Single Cells. During this time period substantial progress has been made in developing low temperature deposition techniques to produce dense, nanocrystalline yttrium-stabilized zirconia films on both dense oxide and polymer substrates. Progress has been made in the preparation and characterization of thin electrolytes and porous LSM substrates. Both of these tasks are essentially on or ahead of schedule. In our proposal, we suggested that the ZrO{sub 2}/Sc system needed to be considered as a candidate as a thin electrolyte. This was because microcrystalline ZrO{sub 2}/Sc has a significantly higher ionic conductivity than YSZ, particularly at the lower temperatures. As a result, some 0.5 micron thick film of ZrO{sub 2}/16% Sc on an alumina substrate (grain size 20nm) was prepared and the electrical conductivity measured as a function of temperature and oxygen activity. The Sc doped ZrO{sub 2} certainly has a higher conductivity that either 20nm or 2400nm YSZ, however, electronic conductivity dominates the conductivity for oxygen activities below 10{sup -15}. Whereas for YSZ, electronic conductivity is not a problem until the oxygen activity decreases below 10{sup -25}. These initial results show that the ionic conductivity of 20nm YSZ and 20nm ZrO{sub 2}/16% Sc are essentially the same and the enhanced conductivity which is observed for Sc doping in microcrystalline specimens is not observed for the same composition when it is nanocrystalline. In addition they show that the electronic conductivity of Sc doped ZrO{sub 2} is at least two orders of magnitude higher than that observed for YSZ. The conclusion one reaches is that for 0.5 to 1 micron thick nanocrystalline films, Sc doping of ZrO{sub 2} has no benefits compared to YSZ. As a result, electrolyte films of ZrO{sub 2}/Sc should not be considered as candidates

  14. Continuous synthesis of methanol: heterogeneous hydrogenation of ethylene carbonate over Cu/HMS catalysts in a fixed bed reactor system.

    Science.gov (United States)

    Chen, Xi; Cui, Yuanyuan; Wen, Chao; Wang, Bin; Dai, Wei-Lin

    2015-09-18

    Continuous fixed-bed catalytic hydrogenation of ethylene carbonate (EC) to methanol and ethylene glycol (EG), an emerging synthetic process of methanol via indirect conversion of CO2, was successfully performed over Cu/HMS catalysts prepared by the ammonia evaporation (AE) method. The catalysts possessed superb performance with a conversion of 100% and a selectivity to methanol of 74%.

  15. Engineered Nanostructured MEA Technology for Low Temperature Fuel Cells

    Energy Technology Data Exchange (ETDEWEB)

    Zhu, Yimin

    2009-07-16

    The objective of this project is to develop a novel catalyst support technology based on unique engineered nanostructures for low temperature fuel cells which: (1) Achieves high catalyst activity and performance; (2) Improves catalyst durability over current technologies; and (3) Reduces catalyst cost. This project is directed at the development of durable catalysts supported by novel support that improves the catalyst utilization and hence reduce the catalyst loading. This project will develop a solid fundamental knowledge base necessary for the synthetic effort while at the same time demonstrating the catalyst advantages in Direct Methanol Fuel Cells (DMFCs).

  16. Electrochemical Synthesis of Mesoporous CoPt Nanowires for Methanol Oxidation

    Directory of Open Access Journals (Sweden)

    Albert Serrà

    2014-03-01

    Full Text Available A new electrochemical method to synthesize mesoporous nanowires of alloys has been developed. Electrochemical deposition in ionic liquid-in-water (IL/W microemulsion has been successful to grow mesoporous CoPt nanowires in the interior of polycarbonate membranes. The viscosity of the medium was high, but it did not avoid the entrance of the microemulsion in the interior of the membrane’s channels. The structure of the IL/W microemulsions, with droplets of ionic liquid (4 nm average diameter dispersed in CoPt aqueous solution, defined the structure of the nanowires, with pores of a few nanometers, because CoPt alloy deposited only from the aqueous component of the microemulsion. The electrodeposition in IL/W microemulsion allows obtaining mesoporous structures in which the small pores must correspond to the size of the droplets of the electrolytic aqueous component of the microemulsion. The IL main phase is like a template for the confined electrodeposition. The comparison of the electrocatalytic behaviours towards methanol oxidation of mesoporous and compact CoPt nanowires of the same composition, demonstrated the porosity of the material. For the same material mass, the CoPt mesoporous nanowires present a surface area 16 times greater than compact ones, and comparable to that observed for commercial carbon-supported platinum nanoparticles.

  17. Facile synthesis of hollow dendritic Ag/Pt alloy nanoparticles for enhanced methanol oxidation efficiency.

    Science.gov (United States)

    Sui, Ning; Wang, Ke; Shan, Xinyao; Bai, Qiang; Wang, Lina; Xiao, Hailian; Liu, Manhong; Colvin, Vicki L; Yu, William W

    2017-11-14

    Hollow dendritic Ag/Pt alloy nanoparticles were synthesized by a double template method: Ag nanoparticles as the hard template to obtain hollow spheres by a galvanic replacement reaction between PtCl 6 2- and metallic Ag and surfactant micelles (Brij58) as the soft template to generate porous dendrites. The formation of a Ag/Pt alloy phase was confirmed by XRD and HRTEM. Elemental mapping and line scanning revealed the formation of the hollow architecture. We studied the effects of the Ag/Pt ratio, surfactant and reaction temperature on the morphology. In addition, we explored the formation process of hollow dendritic Ag/Pt nanoparticles by tracking the morphologies of the nanostructures formed at different stages. In order to improve the electrocatalytic property, we controlled the size of the nanoparticles and the thickness of the shell by adjusting the amount of the precursor. We found that these Ag/Pt alloy nanoparticles exhibited high activity (440 mA mg -1 ) and stability as an electrocatalyst for catalyzing methanol oxidation.

  18. Synthesis and characterization of novel intermetallic catalysts for hydrogenation of carbon dioxide to methanol

    DEFF Research Database (Denmark)

    Fiordaliso, Elisabetta Maria; Sharafutdinov, Irek; Chorkendorff, Ib

    Novel Ni5Ga3 and Pd2Ga catalysts for CO2 hydrogenation to methanol are prepared by impregnation of aqueous Ni-Ga or Pd-Ga solutions of metal nitrates into high surface area SiO2, followed by drying, calcinations and reduction of the precursor in a H2 flow. Steady state experiments are performed...... in a reactor at atmospheric pressure and stoichiometric CO2/H2 mixture, while reaction products are analyzed by gas chromatography. The results are compared to the highly optimized Cu/ZnO/Al2O3. The activity and selectivity of the novel catalysts is close to that of Cu/ZnO/Al2O3 and the equilibrium conversion...... to CH3OH is found to be higher. XRD and XRF are used to investigate the phase and composition of the supported catalysts at the 5 stages of testing, i.e. after drying, calcination, reduction, CO2 hydrogenation, rapid ageing. SEM and TEM images of the exact same locations are acquired after each of the 5...

  19. Seed-mediated synthesis of cross-linked Pt-NiO nanochains for methanol oxidation

    Energy Technology Data Exchange (ETDEWEB)

    Gu, Zhulan; Bin, Duan; Feng, Yue; Zhang, Ke; Wang, Jin; Yan, Bo; Li, Shumin; Xiong, Zhiping; Wang, Caiqin; Shiraishi, Yukihide; Du, Yukou, E-mail: duyk@suda.edu.cn

    2017-07-31

    Highlights: • Cross-linked Pt-NiO nanochains using seed-mediated growth method are synthesized. • The as-prepared catalysts exhibit higher electrocatalytic activity than Pt/C for MOR. • The Pt-NiO(1:1 by molar) catalyst shows the best electrocatalytic property towards MOR. - Abstract: A simple method was reported for employing NiO nanoparticles act as seeds and then different amounts of Pt{sup 2+} were reduced on the NiO nanoparticles, forming a cross-linked Pt-NiO nanocatalysts. These as-prepared catalysts were characterized using different physical-chemical techniques, including X-ray diffraction (XRD), transmission electron microscopy (TEM) and X-ray photoelectron spectroscopy (XPS). The results indicate that the morphology of the cross-linked Pt-NiO nanochain was successfully produced regardless of the molar ratio of Pt{sup 2+} to NiO precursors. The electrochemical characteristics of Pt-NiO nanochain catalysts were evaluated for the oxidation of methanol as a model reaction, which verify that the Pt-NiO catalysts show enhanced activity and high stability in comparison with the commercial Pt/C catalyst. The optimized ratio of Pt to NiO is 1:1, then tuned by simple adjusting the feed ratio of the precursors as well. The synthesized nanocatalysts will be found the great potential applications as electrocatalysts for fuel cells owe to their enhanced catalytic performance and long-term stability.

  20. Controlled Synthesis of Pt Nanowires with Ordered Large Mesopores for Methanol Oxidation Reaction

    Science.gov (United States)

    Zhang, Chengwei; Xu, Lianbin; Yan, Yushan; Chen, Jianfeng

    2016-08-01

    Catalysts for methanol oxidation reaction (MOR) are at the heart of key green-energy fuel cell technology. Nanostructured Pt materials are the most popular and effective catalysts for MOR. Controlling the morphology and structure of Pt nanomaterials can provide opportunities to greatly increase their activity and stability. Ordered nanoporous Pt nanowires with controlled large mesopores (15, 30 and 45 nm) are facilely fabricated by chemical reduction deposition from dual templates using porous anodic aluminum oxide (AAO) membranes with silica nanospheres self-assembled in the channels. The prepared mesoporous Pt nanowires are highly active and stable electrocatalysts for MOR. The mesoporous Pt nanowires with 15 nm mesopores exhibit a large electrochemically active surface area (ECSA, 40.5 m2 g-1), a high mass activity (398 mA mg-1) and specific activity (0.98 mA cm-2), and a good If/Ib ratio (1.15), better than the other mesoporous Pt nanowires and the commercial Pt black catalyst.

  1. Seed-mediated synthesis of cross-linked Pt-NiO nanochains for methanol oxidation

    Science.gov (United States)

    Gu, Zhulan; Bin, Duan; Feng, Yue; Zhang, Ke; Wang, Jin; Yan, Bo; Li, Shumin; Xiong, Zhiping; Wang, Caiqin; Shiraishi, Yukihide; Du, Yukou

    2017-07-01

    A simple method was reported for employing NiO nanoparticles act as seeds and then different amounts of Pt2+ were reduced on the NiO nanoparticles, forming a cross-linked Pt-NiO nanocatalysts. These as-prepared catalysts were characterized using different physical-chemical techniques, including X-ray diffraction (XRD), transmission electron microscopy (TEM) and X-ray photoelectron spectroscopy (XPS). The results indicate that the morphology of the cross-linked Pt-NiO nanochain was successfully produced regardless of the molar ratio of Pt2+ to NiO precursors. The electrochemical characteristics of Pt-NiO nanochain catalysts were evaluated for the oxidation of methanol as a model reaction, which verify that the Pt-NiO catalysts show enhanced activity and high stability in comparison with the commercial Pt/C catalyst. The optimized ratio of Pt to NiO is 1:1, then tuned by simple adjusting the feed ratio of the precursors as well. The synthesized nanocatalysts will be found the great potential applications as electrocatalysts for fuel cells owe to their enhanced catalytic performance and long-term stability.

  2. Seed-mediated synthesis of cross-linked Pt-NiO nanochains for methanol oxidation

    International Nuclear Information System (INIS)

    Gu, Zhulan; Bin, Duan; Feng, Yue; Zhang, Ke; Wang, Jin; Yan, Bo; Li, Shumin; Xiong, Zhiping; Wang, Caiqin; Shiraishi, Yukihide; Du, Yukou

    2017-01-01

    Highlights: • Cross-linked Pt-NiO nanochains using seed-mediated growth method are synthesized. • The as-prepared catalysts exhibit higher electrocatalytic activity than Pt/C for MOR. • The Pt-NiO(1:1 by molar) catalyst shows the best electrocatalytic property towards MOR. - Abstract: A simple method was reported for employing NiO nanoparticles act as seeds and then different amounts of Pt 2+ were reduced on the NiO nanoparticles, forming a cross-linked Pt-NiO nanocatalysts. These as-prepared catalysts were characterized using different physical-chemical techniques, including X-ray diffraction (XRD), transmission electron microscopy (TEM) and X-ray photoelectron spectroscopy (XPS). The results indicate that the morphology of the cross-linked Pt-NiO nanochain was successfully produced regardless of the molar ratio of Pt 2+ to NiO precursors. The electrochemical characteristics of Pt-NiO nanochain catalysts were evaluated for the oxidation of methanol as a model reaction, which verify that the Pt-NiO catalysts show enhanced activity and high stability in comparison with the commercial Pt/C catalyst. The optimized ratio of Pt to NiO is 1:1, then tuned by simple adjusting the feed ratio of the precursors as well. The synthesized nanocatalysts will be found the great potential applications as electrocatalysts for fuel cells owe to their enhanced catalytic performance and long-term stability.

  3. Application of Mössbauer spectroscopy in industrial heterogeneous catalysis: effect of oxidant on FePO{sub 4} material phase transformations in direct methanol synthesis from methane

    Energy Technology Data Exchange (ETDEWEB)

    Dasireddy, Venkata D. B. C., E-mail: dasireddy@ki.si [National Institute of Chemistry, Department of Catalysis and Chemical Reaction Engineering (Slovenia); Khan, Faiza B. [Energy Technology (South Africa); Hanzel, Darko [Jozef Stefan Institute (Slovenia); Bharuth-Ram, Krish [Durban University of Technology, Physics Department (South Africa); Likozar, Blaž [National Institute of Chemistry, Department of Catalysis and Chemical Reaction Engineering (Slovenia)

    2017-11-15

    The effect of the FePO{sub 4} material phase transformation in the direct selective oxidation of methane to methanol was studied using various oxidants, i.e. O{sub 2}, H{sub 2}O and N{sub 2}O. The phases of the heterogeneous catalyst applied, before and after the reactions, were characterized by M¨ossbauer spectroscopy. The main reaction products were methanol, carbon monoxide and carbon dioxide, whereas formaldehyde was produced in rather minute amounts. The Mössbauer spectra showed the change of the initial catalyst material, FePO{sub 4} (tridymite-like phase (tdm)), to the reduced metal form, iron(II) pyrophosphate, Fe{sub 2}P{sub 2}O{sub 7}, and thereafter, the material phase change was governed by the oxidation with individual oxidizing species.Mössbauer spectroscopy measurements applied along with X-ray diffraction (XRD) studies on fresh, reduced and spent catalytic materials demonstrated a transformation of the catalyst to a mixture of phases which depended on operating process conditions. Generally, activity was low and should be a subject of further material optimization and engineering, while the selectivity towards methanol at low temperatures applied was adequate. The proceeding redox mechanism should thus play a key role in catalytic material design, while the advantage of iron-based heterogeneous catalysts primarily lies in them being comparably inexpensive and comprising non-critical raw materials only.

  4. Synthesis of Pd₃Co₁@Pt/C core-shell catalysts for methanol-tolerant cathodes of direct methanol fuel cells.

    Science.gov (United States)

    Aricò, Antonino S; Stassi, Alessandro; D'Urso, Claudia; Sebastián, David; Baglio, Vincenzo

    2014-08-18

    A composite Pd-based electrocatalyst consisting of a surface layer of Pt (5 wt.%) supported on a core Pd3Co1 alloy (95 wt.%) and dispersed as nanoparticles on a carbon black support (50 wt.% metal content) was prepared by using a sulphite-complex route. The structure, composition, morphology, and surface properties of the catalyst were investigated by XRD, XRF, TEM, XPS and low-energy ion scattering spectroscopy (LE-ISS). The catalyst showed an enrichment of Pt on the surface and a smaller content of Co in the outermost layers. These characteristics allow a decrease the Pt content in direct methanol fuel cell cathode electrodes (from 1 to 0.06 mg cm(-2)) without significant decay in performance, due also to a better tolerance to methanol permeated through the polymer electrolyte membrane. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  5. Low temperature study of nonstoichiometric titanium carbide

    International Nuclear Information System (INIS)

    Tashmetov, M.Yu.

    2005-05-01

    By low temperature neutron diffraction method was studied structure in nonstoichiometric titanium carbide from room temperature up to 12K. It is found of low temperature phase in titanium carbide- TiC 0.71 . It is established region and borders of this phase. It is determined change of unit cell parameter. (author)

  6. Low-temperature plasma modelling and simulation

    NARCIS (Netherlands)

    Dijk, van J.

    2011-01-01

    Since its inception in the beginning of the twentieth century, low-temperature plasma science has become a major ¿eld of science. Low-temperature plasma sources and gas discharges are found in domestic, industrial, atmospheric and extra-terrestrial settings. Examples of domestic discharges are those

  7. Thermal conductivity at very low temperature

    Energy Technology Data Exchange (ETDEWEB)

    Locatelli, M [CEA Centre d' Etudes Nucleaires de Grenoble, 38 (France). Service des Basses Temperatures

    1976-06-01

    The interest of low and very low temperatures in solid physics and especially that of thermal measurements is briefly mentioned. Some notes on the thermal conductivity of dielectrics, the method and apparatus used to measure this property at very low temperatures (T<1.5K) and some recent results of fundamental and applied research are then presented.

  8. Quantification of zinc atoms in a surface alloy on copper in an industrial-type methanol synthesis catalyst

    DEFF Research Database (Denmark)

    Kuld, Sebastian; Moses, Poul Georg; Sehested, Jens

    2014-01-01

    Methanol has recently attracted renewed interest because of its potential importance as a solar fuel.1 Methanol is also an important bulk chemical that is most efficiently formed over the industrial Cu/ZnO/Al2O3 catalyst. The identity of the active site and, in particular, the role of ZnO as a pr...

  9. A theoretical analysis of methanol synthesis from CO2 and H2 in a ceramic membrane reactor

    NARCIS (Netherlands)

    Gallucci, F.; Basile, A.

    2007-01-01

    In this theoretical work the CO2 conversion into methanol in both a traditional reactor (TR) and a membrane reactor (MR) is considered. The purpose of this study was to investigate the possibility of increasing CO2 conversion into methanol with respect to a TR. A zeolite MR, able to combine

  10. Development of methanol evaporation plate to reduce methanol crossover in a direct methanol fuel cell

    Science.gov (United States)

    Zhang, Ruiming

    This research focuses on methanol crossover reduction in direct methanol fuel cells (DMFC) through separating the methanol vapor from its liquid phase and feeding the vapor passively at low temperature range. Membrane electrode assemblies (MEAs) were fabricated by using commercial available membrane with different thickness at different anode catalyst loading levels, and tested under the operating conditions below 100°C in cell temperature and cathode exit open to ambient pressure. Liquid methanol transport from the anode through the membrane into cathode ("methanol crossover") is identified as one of the major efficiency losses in a DMFC. It is known that the methanol crossover rate in the vapor phase is much lower than in liquid phase. Vapor feed can be achieved by heating the liquid methanol to elevated temperatures (>100°C), but other issues limit the performance of the cell when operating above 100°C. High temperature membranes and much more active cathode catalyst structures are required, and a complex temperature control system must be employed. However, methanol vapor feed can also occur at a lower temperature range (evaporation through a porous body. The methanol crossover with this vapor feed mode is lower compared with the direct liquid methanol feed. A new method of using a methanol evaporation plate (MEP) to separate the vapor from its liquid phase to reduce the liquid methanol crossover at low temperature range is developed. A MEP plays the roles of liquid/vapor methanol phase separation and evaporation in a DMFC. The goal of this study is to develop a MEP with the proper properties to achieve high methanol phase separation efficiency and fast methanol evaporation rate over a wide range of temperature, i.e., from room temperature up to near boiling temperature (100°C). MEP materials were selected and characterized. MEPs made from three different types were tested extensively with different MEA and porous back layer configurations. The benefits of

  11. Green synthesis of Pt-on-Pd bimetallic nanodendrites on graphene via in situ reduction, and their enhanced electrocatalytic activity for methanol oxidation

    International Nuclear Information System (INIS)

    Cai, Zhi-xiong; Liu, Cong-cong; Wu, Geng-huang; Chen, Xiao-mei; Chen, Xi

    2014-01-01

    Graphical abstract: - Highlights: • Porous 3D dendrite-like structure of Pt-on-Pd bimetallic nanostructures supported on graphene were prepared. • The surface of nanostructures was very “clean” because of the surfactant-free formation process and the use of green reagent. • The hetero-nanostructures showed excellent electrocatalytic performance in methanol oxidation. - Abstract: A green synthesis of Pt-on-Pd bimetallic nanodendrites supported on graphene (GPtPdNDs) with a Pd interior and a dendrite-like Pt exterior was achieved using a two-step preparation, mixing graphene and PdCl 4 2− first, then adding PtCl 4 2− and ethanol without any other solvent. The morphology, structure and composition of the thus-prepared GPtPdNDs were characterized by transmission electron microscopy (TEM), high resolution TEM, energy-dispersive X-ray spectroscopy and X-ray photoelectron spectroscopy. Because no halide ions (refer in particular to Br - , I − ) or surfactant was involved in the synthesis, the prepared GPtPdNDs were directly modified onto a glassy carbon electrode and showed excellent electrocatalytic performance in methanol oxidation without any pretreatments. Moreover, with the special structure of PtPdNDs and the synergetic effects of Pt and Pd and the enhanced electron transfer by graphene, the GPtPdNDs composites exhibited higher electrocatalytic activity and better tolerance to Pt nanoparticles supported on graphene (GPtNPs) and Pt/C for methanol oxidation

  12. Deciding between carbon trading and carbon capture and sequestration: an optimisation-based case study for methanol synthesis from syngas.

    Science.gov (United States)

    Üçtuğ, Fehmi Görkem; Ağralı, Semra; Arıkan, Yıldız; Avcıoğlu, Eray

    2014-01-01

    The economic and technical feasibility of carbon capture and sequestration (CCS) systems are gaining importance as CO2 emission reduction is becoming a more pressing issue for parties from production sectors. Public and private entities have to comply with national schemes imposing tighter limits on their emission allowances. Often these parties face two options as whether to invest in CCS or buy carbon credits for the excess emissions above their limits. CCS is an expensive system to invest in and to operate. Therefore, its feasibility depends on the carbon credit prices prevailing in the markets now and in the future. In this paper we consider the problem of installing a CCS unit in order to ensure that the amount of CO2 emissions is within its allowable limits. We formulate this problem as a non-linear optimisation problem where the objective is to maximise the net returns from pursuing an optimal mix of the two options described above. General Algebraic Modelling Systems (GAMS) software was used to solve the model. The results were found to be sensitive to carbon credit prices and the discount rate, which determines the choices with respect to the future and the present. The model was applied to a methanol synthesis plant as an example. However, the formulation can easily be extended to any production process if the CO2 emissions level per unit of physical production is known. The results showed that for CCS to be feasible, carbon credit prices must be above 15 Euros per ton. This value, naturally, depends on the plant-specific data, and the costs we have employed for CCS. The actual prices (≈5 Euros/ton CO2) at present are far from encouraging the investors into CCS technology. Copyright © 2013 Elsevier Ltd. All rights reserved.

  13. Extremely low temperature properties of epoxy GFRP

    International Nuclear Information System (INIS)

    Kadotani, Kenzo; Nagai, Matao; Aki, Fumitake.

    1983-01-01

    The examination of fiber-reinforced plastics, that is, plastics such as epoxy, polyester and polyimide reinforced with high strength fibers such as glass, carbon, boron and steel, for extremely low temperature use began from the fuel tanks of rockets. Therafter, the trial manufacture of superconducting generators and extremely low temperature transformers and the manufacture of superconducting magnets for nuclear fusion experimental setups became active, and high performance FRPs have been adopted, of which the extremely low temperature properties have been sufficiently grasped. Recently, the cryostats made of FRPs have been developed, fully utilizing such features of FRPs as high strength, high rigidity, non-magnetic material, insulation, low heat conductivity, light weight and the freedom of molding. In this paper, the mechanical properties at extremely low temperature of the plastic composite materials used as insulators and structural materials for extremely low temperature superconducting equipment is outlined, and in particular, glass fiber-reinforced epoxy laminates are described somewhat in detail. The fracture strain of GFRP at extremely low temperature is about 1.3 times as large as that at room temperature, but at extremely low temperature, clear cracking occurred at 40% of the fracture strain. The linear thermal contraction of GFRP showed remarkable anisotropy. (Kako, I.)

  14. Improved Low Temperature Performance of Supercapacitors

    Science.gov (United States)

    Brandon, Erik J.; West, William C.; Smart, Marshall C.; Gnanaraj, Joe

    2013-01-01

    Low temperature double-layer capacitor operation enabled by: - Base acetonitrile / TEATFB salt formulation - Addition of low melting point formates, esters and cyclic ethers center dot Key electrolyte design factors: - Volume of co-solvent - Concentration of salt center dot Capacity increased through higher capacity electrodes: - Zeolite templated carbons - Asymmetric cell designs center dot Continuing efforts - Improve asymmetric cell performance at low temperature - Cycle life testing Motivation center dot Benchmark performance of commercial cells center dot Approaches for designing low temperature systems - Symmetric cells (activated carbon electrodes) - Symmetric cells (zeolite templated carbon electrodes) - Asymmetric cells (lithium titanate/activated carbon electrodes) center dot Experimental results center dot Summary

  15. Analysis of low-temperature tar fractions

    Energy Technology Data Exchange (ETDEWEB)

    Kikkawa, S; Yamada, F

    1952-01-01

    A preliminary comparative study was made on the applicability of the methods commonly used for the type analysis of petroleum products to the low-temperature tar fractions. The usability of chromatography was also studied.

  16. Preparation and Characterization of Cu and Ni on Alumina Supports and Their Use in the Synthesis of Low-Temperature Metal-Phthalocyanine Using a Parallel-Plate Reactor

    Directory of Open Access Journals (Sweden)

    Carlos J. Lucio-Ortiz

    2013-09-01

    Full Text Available Ni- and Cu/alumina powders were prepared and characterized by X-ray diffraction (XRD, scanning electronic microscope (SEM, and N2 physisorption isotherms were also determined. The Ni/Al2O3 sample reveled agglomerated (1 μm of nanoparticles of Ni (30–80 nm however, NiO particles were also identified, probably for the low temperature during the H2 reduction treatment (350 °C, the Cu/Al2O3 sample presented agglomerates (1–1.5 μm of nanoparticles (70–150 nm, but only of pure copper. Both surface morphologies were different, but resulted in mesoporous material, with a higher specificity for the Ni sample. The surfaces were used in a new proposal for producing copper and nickel phthalocyanines using a parallel-plate reactor. Phthalonitrile was used and metallic particles were deposited on alumina in ethanol solution with CH3ONa at low temperatures; ≤60 °C. The mass-transfer was evaluated in reaction testing with a recent three-resistance model. The kinetics were studied with a Langmuir-Hinshelwood model. The activation energy and Thiele modulus revealed a slow surface reaction. The nickel sample was the most active, influenced by the NiO morphology and phthalonitrile adsorption.

  17. Low temperature plasma technology methods and applications

    CERN Document Server

    Chu, Paul K

    2013-01-01

    Written by a team of pioneering scientists from around the world, Low Temperature Plasma Technology: Methods and Applications brings together recent technological advances and research in the rapidly growing field of low temperature plasmas. The book provides a comprehensive overview of related phenomena such as plasma bullets, plasma penetration into biofilms, discharge-mode transition of atmospheric pressure plasmas, and self-organization of microdischarges. It describes relevant technology and diagnostics, including nanosecond pulsed discharge, cavity ringdown spectroscopy, and laser-induce

  18. Direct synthesis of 2-methyl-1-propanol/methanol fuels and feedstocks: Quarterly technical progress report for the period June--August 1985

    Energy Technology Data Exchange (ETDEWEB)

    Klier, K.; Herman, R. G.; Simmons, G. W.; Nunan, J.; Himelfarb, P. B.

    1985-09-01

    During the present quarter, and intensive series of aluminum- supported catalysts, both Cs promoted and unpromoted, have been prepared by a special preparation technique and tested to determine alcohol synthesis activity, selectivities, and stability. Preparation of a single-phase hydrotalcite-like ((Cu/sub x/Zn/sub 1 -x/)/sub 6/Al/sub 2/CO/sub 3/(OH)/sub 16//center dot/4H/sub 2/O) catalyst precursor has been successfully accomplished. Some of these catalysts have been tested to determine their activities in producing methanol and higher alcohols. It has been observed that catalysts obtained by calcination and reduction of the hydrotalcite-like precursor are very active methanol synthesis catalysts. Doping these catalysts with cesium in an aqueous solution leads to initial deactivation, which is partially recovered by doping at higher cesium levels. Results give us guidelines for altering the promoter doping procedure so that a more active and selective aluminum-supported higher alcohol synthesis catalyst will be obtained. 4 refs., 13 figs., 13 tabs.

  19. Cobalt catalysts, and use thereof for the conversion of methanol and for fischer-tropsch synthesis, to produce hydrocarbons

    International Nuclear Information System (INIS)

    Mauldin, C.H.; Davis, S.M.; Arcuri, K.B.

    1988-01-01

    This patent describes a process useful for the conversion of methanol to hydrocarbons which comprises contacting the methanol at reaction conditions with a catalyst which comprises from about 2 percent to about 25 percent cobalt, based on the weight of the catalyst composition, composited with titania, or a titania-containing support, to which is added a zirconium, hafnium, cerium, or uranium promoter, the weight ratio of the zirconium, hafnium, cerium, or uranium metal:cobalt being greater than about 0.010:1; the reaction conditions being defined within ranges as follows: Methanol:H/sub 2/ ratio: greater than about 4:1, Space Velocities, Hr/sup -1/:about 0.1 to 10, Temperatures, 0 C.:about 150 to 350, Methanol Partial Pressure, psia: about 100 to 1000

  20. Bi-reforming of methane from any source with steam and carbon dioxide exclusively to metgas (CO-2H2) for methanol and hydrocarbon synthesis.

    Science.gov (United States)

    Olah, George A; Goeppert, Alain; Czaun, Miklos; Prakash, G K Surya

    2013-01-16

    A catalyst based on nickel oxide on magnesium oxide (NiO/MgO) thermally activated under hydrogen is effective for the bi-reforming with steam and CO(2) (combined steam and dry reforming) of methane as well as natural gas in a tubular flow reactor at elevated pressures (5-30 atm) and temperatures (800-950 °C). By adjusting the CO(2)-to-steam ratio in the gas feed, the H(2)/CO ratio in the produced syn-gas could be easily adjusted in a single step to the desired value of 2 for methanol and hydrocarbon synthesis.

  1. Minimizing material damage using low temperature irradiation

    International Nuclear Information System (INIS)

    Craven, E.; Hasanain, F.; Winters, M.

    2012-01-01

    Scientific advancements in healthcare driven both by technological breakthroughs and an aging and increasingly obese population have lead to a changing medical device market. Complex products and devices are being developed to meet the demands of leading edge medical procedures. Specialized materials in these medical devices, including pharmaceuticals and biologics as well as exotic polymers present a challenge for radiation sterilization as many of these components cannot withstand conventional irradiation methods. The irradiation of materials at dry ice temperatures has emerged as a technique that can be used to decrease the radiation sensitivity of materials. The purpose of this study is to examine the effect of low temperature irradiation on a variety of polymer materials, and over a range of temperatures from 0 °C down to −80 °C. The effectiveness of microbial kill is also investigated under each of these conditions. The results of the study show that the effect of low temperature irradiation is material dependent and can alter the balance between crosslinking and chain scission of the polymer. Low temperatures also increase the dose required to achieve an equivalent microbiological kill, therefore dose setting exercises must be performed under the environmental conditions of use. - Highlights: ► A study is performed to quantify low temperature irradiation effects on polymer materials and BIs. ► Low temperature irradiation alters the balance of cross-linking and chain scissoning in polymers. ► Low temperatures provide radioprotection for BIs. ► Benefits of low temperatures are application specific and must be considered when dose setting.

  2. Synthesis of honeycomb-like mesoporous nitrogen-doped carbon nanospheres as Pt catalyst supports for methanol oxidation in alkaline media

    Science.gov (United States)

    Zhang, Yunmao; Liu, Yong; Liu, Weihua; Li, Xiying; Mao, Liqun

    2017-06-01

    This paper reports the convenient synthesis of honeycomb-like mesoporous nitrogen-doped carbon spheres (MNCS) using a self-assembly strategy that employs dopamine (DA) as a carbon and nitrogen precursor and a polystyrene-b-poly(ethylene oxide) (PS173-b-PEO170) diblock copolymer as a soft template. The MNCS have large BET surface areas of up to 554 m2 g-1 and high nitrogen contents of up to 6.9 wt%. The obtained MNCS are used as a support for Pt catalysts, which promote methanol oxidation in alkaline media. The MNCS-supported Pt (Pt/MNCS) catalyst has a larger electrochemically active surface area (ESA) (89.2 m2 g-1) than does a commercially available Vulcan XC-72R supported Pt/C catalyst. Compared to the Pt/C catalyst, Pt/MNCS displays a higher peak current density (1007 mA mg-1) and is more stable during methanol oxidation. These improvements are attributed to the honeycomb-like porous structure of the MNCS and the introduction of nitrogen to the carbon support. The MNCS effectively stabilize Pt nanoparticles and assuage the agglomeration of the nanoparticles, suggesting that MNCS are potential and promising application as electrocatalyst supports in alkaline direct methanol fuel cells.

  3. Dimethyl carbonate synthesis via transesterification of propylene carbonate with methanol by ceria-zinc catalysts: Role of catalyst support and reaction parameters

    Energy Technology Data Exchange (ETDEWEB)

    Kumar, Praveen; Srivastava, Vimal Chandra; Mishra, Indra Mani [Indian Institute of Technology Roorkee, Roorkee 247667, Uttarakhand (India)

    2015-09-15

    Ceria and zinc oxide catalyst were impregnated onto various oxide supports, namely Al{sub 2}O{sub 3}, TiO{sub 2} and SiO{sub 2}, individually by deposition-coprecipitation method. The synthesized catalysts (CZA, CZS and CZT having supports Al{sub 2}O{sub 3}, TiO{sub 2} and SiO{sub 2}, respectively) were characterized by X-ray diffraction (XRD), NH{sub 3}- and CO{sub 2}-temperature programmed desorption (TPD) and N2 adsorption. These catalysts were used for synthesis of dimethyl carbonate (DMC) from methanol and propylene carbonate in a batch reactor. CZS was found to have larger average grain size as compared to CZA and CZT. Composite oxides (catalysts) were found to contain individual phases of ZnO, CeO{sub 2} and some spinel forms of Zn, Ce along with their supports. CZS having highest basicity and surface area showed better catalytic activity as compared to CZA and CZT. Effect of reaction temperature and methanol/PC molar ratio on DMC yield was studied and a reaction mechanism has been discussed. Maximum DMC yield of 77% was observed with CZS catalyst at 170 .deg. C with methanol/PC molar ratio of 10.

  4. Influence of the Synthesis Method for Pt Catalysts Supported on Highly Mesoporous Carbon Xerogel and Vulcan Carbon Black on the Electro-Oxidation of Methanol

    Directory of Open Access Journals (Sweden)

    Cinthia Alegre

    2015-03-01

    Full Text Available Platinum catalysts supported on carbon xerogel and carbon black (Vulcan were synthesized with the aim of investigating the influence of the characteristics of the support on the electrochemical performance of the catalysts. Three synthesis methods were compared: an impregnation method with two different reducing agents, sodium borohydride and formic acid, and a microemulsion method, in order to study the effect of the synthesis method on the physico-chemical properties of the catalysts. X-ray diffraction and transmission electron microscopy were applied. Cyclic voltammetry and chronoamperometry were used for studying carbon monoxide and methanol oxidation. Catalysts supported on carbon xerogel presented higher catalytic activities towards CO and CH3OH oxidation than catalysts supported on Vulcan. The higher mesoporosity of carbon xerogel was responsible for the favored diffusion of reagents towards catalytic centers.

  5. Basics of Low-temperature Refrigeration

    CERN Document Server

    Alekseev, A.

    2014-07-17

    This chapter gives an overview of the principles of low temperature refrigeration and the thermodynamics behind it. Basic cryogenic processes - Joule-Thomoson process, Brayton process as well as Claude process - are described and compared. A typical helium laboratory refrigerator based on Claude process is used as a typical example of a low-temperature refrigeration system. A description of the hardware components for helium liquefaction is an important part of this paper, because the design of the main hardware components (compressors, turbines, heat exchangers, pumps, adsorbers, etc.) provides the input for cost calculation, as well as enables to estimate the reliability of the plant and the maintenance expenses. All these numbers are necessary to calculate the economics of a low temperature application.

  6. Kinetics and spectroscopy of low temperature plasmas

    CERN Document Server

    Loureiro, Jorge

    2016-01-01

    This is a comprehensive textbook designed for graduate and advanced undergraduate students. Both authors rely on more than 20 years of teaching experience in renowned Physics Engineering courses to write this book addressing the students’ needs. Kinetics and Spectroscopy of Low Temperature Plasmas derives in a full self-consistent way the electron kinetic theory used to describe low temperature plasmas created in the laboratory with an electrical discharge, and presents the main optical spectroscopic diagnostics used to characterize such plasmas. The chapters with the theoretical contents make use of a deductive approach in which the electron kinetic theory applied to plasmas with basis on the electron Boltzmann equation is derived from the basic concepts of Statistical and Plasma Physics. On the other hand, the main optical spectroscopy diagnostics used to characterize experimentally such plasmas are presented and justified from the point of view of the Atomic and Molecular Physics. Low temperature plasmas...

  7. Basics of Low-temperature Refrigeration

    Energy Technology Data Exchange (ETDEWEB)

    Alekseev, A [Linde AG, Munich (Germany)

    2014-07-01

    This chapter gives an overview of the principles of low temperature refrigeration and the thermodynamics behind it. Basic cryogenic processes - Joule-Thomoson process, Brayton process as well as Claude process - are described and compared. A typical helium laboratory refrigerator based on Claude process is used as a typical example of a low-temperature refrigeration system. A description of the hardware components for helium liquefaction is an important part of this paper, because the design of the main hardware components (compressors, turbines, heat exchangers, pumps, adsorbers, etc.) provides the input for cost calculation, as well as enables to estimate the reliability of the plant and the maintenance expenses. All these numbers are necessary to calculate the economics of a low temperature application.

  8. Low temperature monitoring system for subsurface barriers

    Science.gov (United States)

    Vinegar, Harold J [Bellaire, TX; McKinzie, II Billy John [Houston, TX

    2009-08-18

    A system for monitoring temperature of a subsurface low temperature zone is described. The system includes a plurality of freeze wells configured to form the low temperature zone, one or more lasers, and a fiber optic cable coupled to at least one laser. A portion of the fiber optic cable is positioned in at least one freeze well. At least one laser is configured to transmit light pulses into a first end of the fiber optic cable. An analyzer is coupled to the fiber optic cable. The analyzer is configured to receive return signals from the light pulses.

  9. Materials for low-temperature fuel cells

    CERN Document Server

    Ladewig, Bradley; Yan, Yushan; Lu, Max

    2014-01-01

    There are a large number of books available on fuel cells; however, the majority are on specific types of fuel cells such as solid oxide fuel cells, proton exchange membrane fuel cells, or on specific technical aspects of fuel cells, e.g., the system or stack engineering. Thus, there is a need for a book focused on materials requirements in fuel cells. Key Materials in Low-Temperature Fuel Cells is a concise source of the most important and key materials and catalysts in low-temperature fuel cells. A related book will cover key materials in high-temperature fuel cells. The two books form part

  10. Low-temperature carbonization plant for lignite

    Energy Technology Data Exchange (ETDEWEB)

    Shiotsuki, Y

    1949-01-01

    The design and operational data of a low-temperature carbonization plant for Japanese lignite are described. The retort had a vertical cylinder with a capacity of about 10 tons per day. By continuous operation, in which a part of the gas produced was circulated and burned in the lignite zone, about 40 percent semicoke and 3 to 4 percent tar were obtained. From the tar the following products were separated: Low-temperature carbonization cresol, 18.3; motor fuel, 1.00; solvent, 9.97; cresol for medical uses, 11.85; and creosote oil, 32 percent.

  11. Pt-Fe catalyst nanoparticles supported on single-wall carbon nanotubes: Direct synthesis and electrochemical performance for methanol oxidation

    Science.gov (United States)

    Ma, Xiaohui; Luo, Liqiang; Zhu, Limei; Yu, Liming; Sheng, Leimei; An, Kang; Ando, Yoshinori; Zhao, Xinluo

    2013-11-01

    Single-wall carbon nanotubes (SWCNTs) supported Pt-Fe nanoparticles have been prepared by one-step hydrogen arc discharge evaporation of carbon electrode containing both Pt and Fe metal elements. The formation of SWCNTs and Pt-Fe nanoparticles occur simultaneously during the evaporation process. High-temperature hydrogen treatment and hydrochloric acid soaking have been carried out to purify and activate those materials in order to obtain a new type of Pt-Fe/SWCNTs catalyst for methanol oxidation. The Pt-Fe/SWCNTs catalyst performs much higher electrocatalytic activity for methanol oxidation, better stability and better durability than a commercial Pt/C catalyst according to the electrochemical measurements, indicating that it has a great potential for applications in direct methanol fuel cells.

  12. Synthesis of flower-like gold nanoparticles and their electrocatalytic activity towards the oxidation of methanol and the reduction of oxygen.

    Science.gov (United States)

    Jena, Bikash Kumar; Raj, C Retna

    2007-03-27

    This article describes the synthesis of branched flower-like gold (Au) nanocrystals and their electrocatalytic activity toward the oxidation of methanol and the reduction of oxygen. Gold nanoflowers (GNFs) were obtained by a one-pot synthesis using N-2-hydroxyethylpiperazine-N-2-ethanesulphonic acid (HEPES) as a reducing/stabilizing agent. The GNFs have been characterized by UV-visible spectroscopy, transmission electron microscopy (TEM), X-ray diffraction (XRD), and electrochemical measurements. The UV-visible spectra show two bands corresponding to the transverse and longitudinal surface plasmon (SP) absorption at 532 and 720 nm, respectively, for the colloidal GNFs. The GNFs were self-assembled on a sol-gel-derived silicate network, which was preassembled on a polycrystalline Au electrode and used for electrocatalytic applications. The GNFs retain their morphology on the silicate network; the UV-visible diffuse reflectance spectra (DRS) of GNFs on the silicate network show longitudinal and transverse bands as in the case of colloidal GNFs. The GNFs show excellent electrocatalytic activity toward the oxidation of methanol and the reduction of oxygen. Oxidation of methanol in alkaline solution was observed at approximately 0.245 V, which is much less positive than that on an unmodified polycrystalline gold electrode. Reduction of oxygen to H2O2 and the further reduction of H2O2 to water in neutral pH were observed at less negative potentials on the GNFs electrode. The electrocatalytic activity of GNFs is significantly higher than that of the spherically shaped citrate-stabilized Au nanoparticles (SGNs).

  13. Sucrose Phosphate Synthase and Sucrose Accumulation at Low Temperature 1

    Science.gov (United States)

    Guy, Charles L.; Huber, Joan L. A.; Huber, Steven C.

    1992-01-01

    The influence of growth temperature on the free sugar and sucrose phosphate synthase content and activity of spinach (Spinacia oleracea) leaf tissue was studied. When plants were grown at 25°C for 3 weeks and then transferred to a constant 5°C, sucrose, glucose, and fructose accumulated to high levels during a 14-d period. Predawn sugar levels increased from 14- to 20-fold over the levels present at the outset of the low-temperature treatment. Sucrose was the most abundant free sugar before, during, and after exposure to 5°C. Leaf sucrose phosphate synthase activity was significantly increased by the low-temperature treatment, whereas sucrose synthase and invertases were not. Synthesis of the sucrose phosphate synthase subunit was increased during and after low-temperature exposure and paralleled an increase in the steady-state level of the subunit. The increases in sucrose and its primary biosynthetic enzyme, sucrose phosphate synthase, are discussed in relation to adjustment of metabolism to low nonfreezing temperature and freezing stress tolerance. Images Figure 1 Figure 2 Figure 3 PMID:16652990

  14. Synthesis of Novel p-tert-Butylcalix[4]arene Derivative: Structural Characterization of a Methanol Inclusion Compound

    Directory of Open Access Journals (Sweden)

    Silvana Moris

    2016-09-01

    Full Text Available A p-tertbutylcalix[4]arene derivative was synthesized from a reaction of the diisothiocyanate p-tertbutylcalix[4]arene, obtaining crystals that were then characterized by mass spectroscopy, Raman spectroscopy, and single-crystal X-ray diffraction. The molecule presents two acid carbamothioic-n-ethoxy-methyl-ester substituent groups. Through crystallization of this compound, it was also found that it includes a methanol molecule within the aromatic cavity. The inclusion of the methanol molecule is due to favorable CH∙∙∙π interactions.

  15. Supported 3-D Pt nanostructures: the straightforward synthesis and enhanced electrochemical performance for methanol oxidation in an acidic medium

    International Nuclear Information System (INIS)

    Li, Zesheng; Ji, Shan; Pollet, Bruno G.; Shen, Pei Kang

    2013-01-01

    Noble metal nanostructures with branched morphologies [i.e., 3-D Pt nanoflowers (NFs)] by tri-dimensionally integrating onto conductive carbon materials are proved to be an efficient and durable electrocatalysts for methanol oxidation. The well-supported 3-D Pt NFs are readily achieved by an efficient cobalt-induced/carbon-mediated galvanic reaction approach. Due to the favorable nanostructures (3-D Pt configuration allowing a facile mass transfer) and supporting effects (including framework stabilization, spatially separate feature, and improved charge transport effects), these 3-D Pt NFs manifest much higher electrocatalytic activity and stability toward methanol oxidation than that of the commercial Pt/C and Pt-based electrocatalysts

  16. Supported 3-D Pt nanostructures: the straightforward synthesis and enhanced electrochemical performance for methanol oxidation in an acidic medium

    Energy Technology Data Exchange (ETDEWEB)

    Li, Zesheng [Sun Yat-sen University, The State Key Laboratory of Optoelectronic Materials and Technologies, and Guangdong Province Key Laboratory of Low-carbon Chemistry and Energy Conservation, School of Physics and Engineering (China); Ji, Shan; Pollet, Bruno G. [University of the Western Cape, South African Institute for Advanced Materials Chemistry (SAIAMC) (South Africa); Shen, Pei Kang, E-mail: stsspk@mail.sysu.edu.cn [Sun Yat-sen University, The State Key Laboratory of Optoelectronic Materials and Technologies, and Guangdong Province Key Laboratory of Low-carbon Chemistry and Energy Conservation, School of Physics and Engineering (China)

    2013-10-15

    Noble metal nanostructures with branched morphologies [i.e., 3-D Pt nanoflowers (NFs)] by tri-dimensionally integrating onto conductive carbon materials are proved to be an efficient and durable electrocatalysts for methanol oxidation. The well-supported 3-D Pt NFs are readily achieved by an efficient cobalt-induced/carbon-mediated galvanic reaction approach. Due to the favorable nanostructures (3-D Pt configuration allowing a facile mass transfer) and supporting effects (including framework stabilization, spatially separate feature, and improved charge transport effects), these 3-D Pt NFs manifest much higher electrocatalytic activity and stability toward methanol oxidation than that of the commercial Pt/C and Pt-based electrocatalysts.

  17. Facile synthesis of Li2S-P2S5 glass-ceramics electrolyte with micron range particles for all-solid-state batteries via a low-temperature solution technique (LTST)

    Science.gov (United States)

    Choi, Sunho; Lee, Sewook; Park, Jongyeop; Nichols, William T.; Shin, Dongwook

    2018-06-01

    A lithium ion conductive 75Li2Sṡ25P2S5 glass-ceramics electrolyte is, for the first time, successfully synthesized via a new low-temperature solution technique (LTST) and compared to the conventional mechanical-milling technique. Both samples are composed of the highly lithium ion conductive thio-LISICON III analog phase. Due to the uniform dispersion of reactants in an organic liquid, the use of LTST produced significantly smaller and more uniform particle sizes (2.2 ± 1.68 μm) resulting in a 6.5 times higher specific surface area compared to the mechanically-milled sample. A pronounced enhancement of both the rate capability and cyclability is demonstrated for the LTST solid electrolyte sample due to the more intimate contact with the LiCoO2 active material. Furthermore, the LTST sample shows excellent electrochemical stability throughout the potential range of -1 to 5 V. These results suggest that the proposed technique using the optimized LTST process is promising for the preparation of 75Li2Sṡ25P2S5 solid electrolytes for use in advanced Li-ion batteries.

  18. Low temperature thermophysical properties of lunar soil

    Science.gov (United States)

    Cremers, C. J.

    1973-01-01

    The thermal conductivity and thermal diffusivity of lunar fines samples from the Apollo 11 and Apollo 12 missions, determined at low temperatures as a function of temperature and various densities, are reviewed. It is shown that the thermal conductivity of lunar soil is nearly the same as that of terrestrial basaltic rock under the same temperature and pressure conditions.

  19. Neutrinos, dark matter and low temperature detectors

    International Nuclear Information System (INIS)

    Gonzalez-Mestres, L.; Perret-Gallix, D.

    1988-01-01

    The present status of cryogenic detector developments for particle physics is discussed, with emphasis on applications at the cross-disciplinary frontier between particle physics and astrophysics, where low temperature devices appear to be particularly well suited. The overwiew of results is completed by a sketch of new ideas and possible ways for further improvements. Neutrino role importance is particularly shown

  20. Low Temperature Cure Powder Coatings (LTCPC)

    Science.gov (United States)

    2010-10-01

    Dr. Glen Merfeld, General Electric Global Research evaluated and optimized the formulation, and cure and performance parameters of candidate LTCPC...Unacceptable test result = Marginal test result = Acceptable test result 80 therefore suffer from brittleness at extremely low temperatures. NASA’s

  1. Industrial Applications of Low Temperature Plasmas

    International Nuclear Information System (INIS)

    Bardsley, J N

    2001-01-01

    The use of low temperature plasmas in industry is illustrated by the discussion of four applications, to lighting, displays, semiconductor manufacturing and pollution control. The type of plasma required for each application is described and typical materials are identified. The need to understand radical formation, ionization and metastable excitation within the discharge and the importance of surface reactions are stressed

  2. Low temperature anodic bonding to silicon nitride

    DEFF Research Database (Denmark)

    Weichel, Steen; Reus, Roger De; Bouaidat, Salim

    2000-01-01

    Low-temperature anodic bonding to stoichiometric silicon nitride surfaces has been performed in the temperature range from 3508C to 4008C. It is shown that the bonding is improved considerably if the nitride surfaces are either oxidized or exposed to an oxygen plasma prior to the bonding. Both bu...

  3. Arc generators of low-temperature plasma

    International Nuclear Information System (INIS)

    Krolikowski, Cz.; Niewiedzial, R.; Siwiec, J.

    1979-01-01

    This paper is a review of works concerning investigation and use of low-temperature plasma in arc plasma generators made in Electric Power Institute of PP. There are discussed: analytical approach to a problem of volt-current and operational characteristics of DC arc plasma generators, determination of limits of their stable work and possibilities of their use to technological aims. (author)

  4. Methanol Oxidation on Pt3Sn(111) for Direct Methanol Fuel Cells: Methanol Decomposition.

    Science.gov (United States)

    Lu, Xiaoqing; Deng, Zhigang; Guo, Chen; Wang, Weili; Wei, Shuxian; Ng, Siu-Pang; Chen, Xiangfeng; Ding, Ning; Guo, Wenyue; Wu, Chi-Man Lawrence

    2016-05-18

    PtSn alloy, which is a potential material for use in direct methanol fuel cells, can efficiently promote methanol oxidation and alleviate the CO poisoning problem. Herein, methanol decomposition on Pt3Sn(111) was systematically investigated using periodic density functional theory and microkinetic modeling. The geometries and energies of all of the involved species were analyzed, and the decomposition network was mapped out to elaborate the reaction mechanisms. Our results indicated that methanol and formaldehyde were weakly adsorbed, and the other derivatives (CHxOHy, x = 1-3, y = 0-1) were strongly adsorbed and preferred decomposition rather than desorption on Pt3Sn(111). The competitive methanol decomposition started with the initial O-H bond scission followed by successive C-H bond scissions, (i.e., CH3OH → CH3O → CH2O → CHO → CO). The Brønsted-Evans-Polanyi relations and energy barrier decomposition analyses identified the C-H and O-H bond scissions as being more competitive than the C-O bond scission. Microkinetic modeling confirmed that the vast majority of the intermediates and products from methanol decomposition would escape from the Pt3Sn(111) surface at a relatively low temperature, and the coverage of the CO residue decreased with an increase in the temperature and decrease in partial methanol pressure.

  5. Methanol as an energy carrier

    Energy Technology Data Exchange (ETDEWEB)

    Biedermann, P.; Grube, T.; Hoehlein, B. (eds.)

    2006-07-01

    For the future, a strongly growing energy demand is expected in the transport sector worldwide. Economically efficient oil production will run through a maximum in the next decade. Higher fuel prices and an environmentally desirable reduction of emissions will increase the pressure for reducing fuel consumption and emissions in road traffic. These criteria show the urgent necessity of structural changes in the fuel market. Due to its advantages concerning industrial-scale production, storage and global availability, methanol has the short- to medium-term potential for gaining increased significance as a substitution product in the energy market. Methanol can be produced both from fossil energy sources and from biomass or waste materials through the process steps of synthesis gas generation with subsequent methanol synthesis. Methanol has the potential to be used in an environmentally friendly manner in gasoline/methanol mixtures for flexible fuel vehicles with internal combustion engines and in diesel engines with pure methanol. Furthermore, it can be used in fuel cell vehicles with on-board hydrogen production in direct methanol fuel cell drives, and in stationary systems for electricity and heat generation as well as for hydrogen production. Finally, in portable applications it serves as an energy carrier for electric power generation. In this book, the processes for the production and use of methanol are presented and evaluated, markets and future options are discussed and issues of safety and environmental impacts are addressed by a team of well-known authors. (orig.)

  6. Low temperature experiments in radiation biophysics

    International Nuclear Information System (INIS)

    Moan, J.

    1977-01-01

    The reasons for performing experiments in radiation biophysics at low temperatures, whereby electron spectra may be studied, are explained. The phenomenon of phosphorescence spectra observed in frozen aqueous solutions of tryptophan and adenosine is also described. Free radicals play an important part in biological radiation effects and may be studied by ESR spectroscopy. An ESR spectrum of T 1 bacteriophages irradiated dry at 130K is illustrated and discussed. Hydrogen atoms, which give lines on the spectrum, are believed to be those radiation products causing most biological damage in a dry system. Low temperature experiments are of great help in explaining the significance of direct and indirect effects. This is illustrated for the case of trypsin. (JIW)

  7. Dehydration of hydrated low-temperature tar

    Energy Technology Data Exchange (ETDEWEB)

    Yoshida, T

    1949-01-01

    Yoshida examined the mechanism of the dehydration of hydrated low-temperature tar with a microscope. The tar containing free carbon and coal dust is so stable that the removal of the above substances and water by a physical method is very difficult. Addition of light oil produced by fractionation of low-temperature tar facilitates the operations. Yoshida tried using the separate acid, neutral, and basic components of the light oil; the acid oil proved to be most effective. For many reasons it is convenient to use light oil as it is. In this method the quantity of light oil required is 2 to 3 times that of tar. But in supplementing the centrifugal method, the quantity of light oil needed might be only half the amount of tar.

  8. Technological uses of low temperature plasmas

    International Nuclear Information System (INIS)

    Lawton, J.

    1975-01-01

    Types of low temperature plasma sources considered include; arc discharge, high pressure discharge, low pressure discharge and flame. The problems of uniform heating of a gas are discussed and it is considered that the most reliable technique is the magnetically rotated arc, but expanded discharges of one kind or another are likely to be serious competitors in the future. The uses of low temperature plasma in chemistry and combustion are considered. The potential for plasma chemistry lies with processes in which the reactions occur in the plasma itself or its neighbouring gas phase, including those which require the vaporization of liquefaction of a refractory material and also highly endothermic reactions. The production of thixotropic silica and acetylene are discussed as examples of such reactions. The field of plasma and combustion including; ignition, flame ionization and soot formation, and the MHD generator, is considered. (U.K.)

  9. Behaviour of polar crystals at low temperatures

    International Nuclear Information System (INIS)

    Drozhdin, S.N.; Novik, V.K.; Gavrilova, N.D.; Koptsik, V.A.; Popova, T.V.

    1975-01-01

    Temperature dependencies of pyrocoefficient for a wide class of various pyroactive crystals in the temperature range from 4,2 to 300 deg K were investigated. The problems to be solved were: to confirm a conclusion on the pyrocoefficient γsup(sigma) tending to zero at T → 0; to compare experimental data with conclusions of existing theories; to reveal specific features in the behaviour of both linear pyroelectrics and segnetoelectrics at low temperatures. The behaviour of the total pyrocoefficient for all crystals obeys the regularity γsup(sigma) → 0 at T → O. In the range of low temperatures the pyrocoefficient varies by the power law: γsup(sigma) approximately Tsup(α). For the majority of crystals studied α is close to 3. CdS, BeO, ZiNbO 3 and other crystals were studied

  10. Low-temperature conductivity of gadolinium sulfides

    Energy Technology Data Exchange (ETDEWEB)

    Mustafaeva, S. N., E-mail: solmust@gmail.com [Azerbaijan National Academy of Sciences, Institute of Physics (Azerbaijan); Asadov, S. M., E-mail: mirasadov@gmail.com [Azerbaijan National Academy of Sciences, Institute of Catalysis and Inorganic Chemistry (Azerbaijan)

    2016-09-15

    In samples of GdS{sub x} (x = 1.475–2) of various compositions, the conductivity temperature dependences are investigated for the case of direct current in the low-temperature region (4.2–225 K). The presence of the activation and activationless hopping mechanisms of charge transport over the band gap of the samples of GdS{sub x} phases is established. The parameters of localized states in GdS{sub x} are determined.

  11. Thermodynamic power stations at low temperatures

    Science.gov (United States)

    Malherbe, J.; Ployart, R.; Alleau, T.; Bandelier, P.; Lauro, F.

    The development of low-temperature thermodynamic power stations using solar energy is considered, with special attention given to the choice of the thermodynamic cycle (Rankine), working fluids (frigorific halogen compounds), and heat exchangers. Thermomechanical conversion machines, such as ac motors and rotating volumetric motors are discussed. A system is recommended for the use of solar energy for irrigation and pumping in remote areas. Other applications include the production of cold of fresh water from brackish waters, and energy recovery from hot springs.

  12. Crystal growth from low-temperature solutions

    International Nuclear Information System (INIS)

    Sangwal, K.

    1994-01-01

    The state of the art in crystal growth from solutions at low-temperatures has been done. The thermodynamic and kinetic parameters have been discussed in respect to different systems. The methods of crystal growth from water and organic solutions and different variants of their technical realizations have been reviewed. Also the growth by chemical reactions and gel growth have been described. The large number of examples have been shown. 21 refs, 30 figs, 3 tabs

  13. Methanol and carbonylation

    Energy Technology Data Exchange (ETDEWEB)

    Gauthier-Lafaye, J.; Perron, R.

    1987-01-01

    The overall focus of the book is on homogeneous catalysed processes which were seen to offer the most promising routes to C/sub 2/ oxygenates. The first three chapters review the industrial synthesis and applications of carbon monoxide such as in the manufacture of gasoline (e.g. Fischer-Tropsch, Mobil processes), organic chemicals (e.g. ethanol, acetic acid, etc.), industrial importance of C/sub 2/ oxygenates, and use of methanol as a future feedstock are discussed. The next six chapters are each concerned with the production of a particular C/sub 2/ oxygenate and a detailed analysis of the methods and catalysts used. The hydrocarbonylation of methanol occupies a large chapter (136 references) with a comparative examination of the catalysts available, and their modification to increase selectivity to either acetylaldehyde or ethanol. Following chapters examine the synthesis of ethyl acetate, acetic acid, acetic anhydride, vinyl acetate, ethylene glycol and oxalic acid.

  14. Low temperature synthesis of no-carrier-added [{sup 11}C]formaldehyde with metal hydrides and preparation of [1-{sup 11}C]1,2,3,4-Tetrahydro-{beta}-Carboline Derivatives

    Energy Technology Data Exchange (ETDEWEB)

    Nader, M.W.; Zeisler, S.K.; Theobald, A.; Oberdorfer, F

    1998-12-01

    A comparative study has been performed on the selective reduction of cyclotron-produced [{sup 11}C]carbon dioxide to [{sup 11}C]formaldehyde with solutions of various complex metal hydrides at temperatures between -52 and +25 deg. C. Under optimal reaction conditions, lithium tetrahydridoaluminate gave the highest yield of [{sup 11}C]formaldehyde (58%, decay-corrected), followed by lithium triethylhydridoborate (34%) and sodium tetrahydridoborate (22%). Radiochemically pure [{sup 11}C]formaldehyde could be obtained with lithium tetrahydridoaluminate and sodium tetrahydridoborate, but not with lithium triethyl hydridoborate. The produced [{sup 11}C]formaldehyde was used for the synthesis of [1-{sup 11}C]1,2,3,4-tetrahydro-{beta}-carboline derivatives by the Pictet-Spengler reaction.

  15. Minimizing material damage using low temperature irradiation

    Science.gov (United States)

    Craven, E.; Hasanain, F.; Winters, M.

    2012-08-01

    Scientific advancements in healthcare driven both by technological breakthroughs and an aging and increasingly obese population have lead to a changing medical device market. Complex products and devices are being developed to meet the demands of leading edge medical procedures. Specialized materials in these medical devices, including pharmaceuticals and biologics as well as exotic polymers present a challenge for radiation sterilization as many of these components cannot withstand conventional irradiation methods. The irradiation of materials at dry ice temperatures has emerged as a technique that can be used to decrease the radiation sensitivity of materials. The purpose of this study is to examine the effect of low temperature irradiation on a variety of polymer materials, and over a range of temperatures from 0 °C down to -80 °C. The effectiveness of microbial kill is also investigated under each of these conditions. The results of the study show that the effect of low temperature irradiation is material dependent and can alter the balance between crosslinking and chain scission of the polymer. Low temperatures also increase the dose required to achieve an equivalent microbiological kill, therefore dose setting exercises must be performed under the environmental conditions of use.

  16. Computational Chemistry of Cyclopentane Low Temperature Oxidation

    KAUST Repository

    El Rachidi, Mariam

    2015-03-30

    Cycloalkanes are significant constituents of conventional fossil fuels, but little is known concerning their combustion chemistry and kinetics, particularly at low temperatures. This study investigates the pressure dependent kinetics of several reactions occurring during low-temperature cyclopentane combustion using theoretical chemical kinetics. The reaction pathways of the cyclopentyl + O2 adduct is traced to alkylhydroperoxide, cyclic ether, β-scission and HO2 elimination products. The calculations are carried out at the UCCSD(T)-F12b/cc-pVTZ-F12//M06-2X/6-311++G(d,p) level of theory. The barrierless entrance channel is treated using variable-reaction-coordinate transition state theory (VRC-TST) at the CASPT2(7e,6o) level of theory, including basis set, geometry relaxation and ZPE corrections. 1-D time-dependent multiwell master equation analysis is used to determine pressure-and temperature-dependent rate parameters of all investigated reactions. Tunneling corrections are included using Eckart barriers. Comparison with cyclohexane is used to elucidate the effect of ring size on the low temperature reactivity of naphthenes. The rate coefficients reported herein are suitable for use in cyclopentane and methylcyclopentane combustion models, even below ~900 K, where ignition is particularly sensitive to these pressure-dependent values.

  17. Neutron moderation at very low temperatures (1691)

    International Nuclear Information System (INIS)

    Lacaze, A.

    1961-04-01

    Starting from Harwell experiment carried out inside a low-power reactor, we intended to maintain a liquid hydrogen cell in a channel of the EL3 reactor (at Saclay) whose thermal neutrons flux is 10 14 neutrons/cm 2 /s. We tried to work out a device giving off an important beam of cold neutrons and able to operate in a way as automatic as possible during many consecutive day without a stop. Several circuits have already been achieved at very low temperatures but they brought out volumes and fluxes much lower than those we used this time. The difficulties we have met in carrying out such a device arose on the one hand from the very high energy release to which any kind of experiment is inevitably submitted when placed near the core of the reactor, on the other, hand from the very little room which is available in experimental channels of reactors. In such condition, it is necessary to use a moderator as effective as possible. This study is divided into three parts ; in the first part, we try to determine: a) conditions in which moderation takes place, hence the volume of the cell; b) materials likely to be used at low temperature and in pile; c) cooling system; hence we had to study fluid flow conditions at very low temperatures in very long ducts. The second part is devoted to the description of the device. The third part ventilates the results we have obtained. (author) [fr

  18. Low temperature surface chemistry and nanostructures

    Science.gov (United States)

    Sergeev, G. B.; Shabatina, T. I.

    2002-03-01

    The new scientific field of low temperature surface chemistry, which combines the low temperature chemistry (cryochemistry) and surface chemistry approaches, is reviewed in this paper. One of the most exciting achievements in this field of science is the development of methods to create highly ordered hybrid nanosized structures on different organic and inorganic surfaces and to encapsulate nanosized metal particles in organic and polymer matrices. We consider physical and chemical behaviour for the systems obtained by co-condensation of the components vapours on the surfaces cooled down to 4-10 and 70-100 K. In particular the size effect of both types, the number of atoms in the reactive species structure and the thickness of growing co-condensate film, on the chemical activity of the system is analysed in detail. The effect of the internal mechanical stresses on the growing interfacial co-condensate film formation and on the generation of fast (explosive) spontaneous reactions at low temperatures is discussed. The examples of unusual chemical interactions of metal atoms, clusters and nanosized particles, obtained in co-condensate films on the cooled surfaces under different conditions, are presented. The examples of highly ordered surface and volume hybrid nanostructures formation are analysed.

  19. Plasma-induced synthesis of Pt nanoparticles supported on TiO2 nanotubes for enhanced methanol electro-oxidation

    Science.gov (United States)

    Su, Nan; Hu, Xiulan; Zhang, Jianbo; Huang, Huihong; Cheng, Jiexu; Yu, Jinchen; Ge, Chao

    2017-03-01

    A Pt/C/TiO2 nanotube composite catalyst was successfully prepared for enhanced methanol electro-oxidation. Pt nanoparticles with a particle size of 2 nm were synthesized by plasma sputtering in water, and anatase TiO2 nanotubes with an inner diameter of approximately 100 nm were prepared by a simple two-step anodization method and annealing process. Field-emission scanning electron microscopy images indicated that the different morphologies of TiO2 synthesized on the surface of Ti foils were dependent on the different anodization parameters. The electrochemical performance of Pt/C/TiO2 catalysts for methanol oxidation showed that TiO2 nanotubes were more suitable for use as Pt nanoparticle support materials than irregular TiO2 short nanorods due to their tubular morphology and better electronic conductivity. X-ray photoelectron spectroscopy characterization showed that the binding energies of the Pt 4f of the Pt/C/TiO2 nanotubes exhibited a slightly positive shift caused by the relatively strong interaction between Pt and the TiO2 nanotubes, which could mitigate the poisoning of the Pt catalyst by COads, and further enhance the electrocatalytic performance. Thus, the as-obtained Pt/C/TiO2 nanotubes composites may become a promising catalyst for methanol electro-oxidation.

  20. Synthesis of PtNi Alloy Nanoparticles on Graphene-Based Polymer Nanohybrids for Electrocatalytic Oxidation of Methanol

    Directory of Open Access Journals (Sweden)

    Tung-Yuan Yung

    2016-12-01

    Full Text Available We have successfully produced bimetallic PtNi alloy nanoparticles on poly(diallyldimethylammonium chloride (PDDA-modified graphene nanosheets (PtNi/PDDA-G by the “one-pot” hydrothermal method. The size of PtNi alloy nanoparticles is approximately 2–5 nm. The PDDA-modified graphene nanosheets (PDDA-G provides an anchored site for metal precursors; hence, the PtNi nanoparticles could be easily bond on the PDDA-G substrate. PtNi alloy nanoparticles (2–5 nm display a homogenous alloy phase embedded on the PDDA-G substrate, evaluated by Raman, X-ray diffractometer (XRD, thermal gravity analysis (TGA, electron surface chemical analysis (ESCA, and electron energy loss spectroscopy (EELS. The Pt/Ni ratio of PtNi alloy nanoparticles is ~1.7, examined by the energy dispersive spectroscopy (EDS spectra of transmitting electron microscopy (EDS/TEM spectra and mapping technique. The methanol electro-oxidation of PtNi/PDDA-G was evaluated by cyclic voltammetry (CV in 0.5 M of H2SO4 and 0.5 M of CH3OH. Compared to Pt on carbon nanoparticles (Pt/C and Pt on Graphene (Pt/G, the PtNi/PDDA-G exhibits the optimal electrochemical surface area (ECSA, methanol oxidation reaction (MOR activity, and durability by chrono amperometry (CA test, which can be a candidate for MOR in the electro-catalysis of direct methanol fuel cells (DMFC.

  1. Synthesis of methyl esters from relevant palm products in near-critical methanol with modified-zirconia catalysts.

    Science.gov (United States)

    Laosiripojana, N; Kiatkittipong, W; Sutthisripok, W; Assabumrungrat, S

    2010-11-01

    The transesterification and esterification of palm products i.e. crude palm oil (CPO), refined palm oil (RPO) and palm fatty acid distillate (PFAD) under near-critical methanol in the presence of synthesized SO(4)-ZrO(2), WO(3)-ZrO(2) and TiO(2)-ZrO(2) (with various sulfur- and tungsten loadings, Ti/Zr ratios, and calcination temperatures) were studied. Among them, the reaction of RPO with 20%WO(3)-ZrO(2) (calcined at 800 degrees C) enhanced the highest fatty acid methyl ester (FAME) yield with greatest stability after several reaction cycles; furthermore, it required shorter time, lower temperature and less amount of methanol compared to the reactions without catalyst. These benefits were related to the high acid-site density and tetragonal phase formation of synthesized WO(3)-ZrO(2). For further improvement, the addition of toluene as co-solvent considerably reduced the requirement of methanol to maximize FAME yield, while the addition of molecular sieve along with catalyst significantly increased FAME yield from PFAD and CPO due to the inhibition of hydrolysis reaction. Copyright 2010 Elsevier Ltd. All rights reserved.

  2. Direct Synthesis of Methanol by Partial Oxidation of Methane with Oxygen over Cobalt Modified Mesoporous H-ZSM-5 Catalyst

    Directory of Open Access Journals (Sweden)

    Yuni Krisyuningsih Krisnandi

    2015-11-01

    Full Text Available Partial oxidation of methane over mesoporous catalyst cobalt modified H-ZSM-5 has been carried out. Mesoporous Na-ZSM-5 (Si/Al = 35.4 was successfully synthesized using double template method which has high surface area (450 m2/g and average pore diameter distribution of 1.9 nm. The as-synthesized Na-ZSM-5 was converted to H-ZSM-5 through multi-exchange treatment with ammonium ion solution, causing decreased crystallinity and surface area, but increased porous diameter, due to dealumination during treatment process. Moreover, H-ZSM-5 was loaded with cobalt (Co = 2.5% w by the incipient impregnation method and calcined at 550 °C. Partial oxidation of methane was performed in the batch reactor with 0.75 bar methane and 2 bar of nitrogen (with impurities of 0.5% oxygen as the input at various reaction time (30, 60 and 120 min. The reaction results show that cobalt species in catalyst has an important role, because H-ZSM-5 cannot produce methanol in partial oxidation of methane. The presence of molecular oxygen increased the percentage of methanol yield. The reaction is time-dependent with the highest methanol yield (79% was acquired using Co/H-ZSM-5 catalyst for 60 min.

  3. INFLUENCE OF THE ISOBUTENE METHANOL RATIO AND OF THE METHYL TERT-BUTYL ETHER CONTENT ON THE REACTION-RATE OF THE SYNTHESIS OF METHYL TERT-BUTYL ETHER

    NARCIS (Netherlands)

    PANNEMAN, HJ; BEENACKERS, AACM

    1995-01-01

    The forward reaction rate constant of the MtBE synthesis was determined for different reaction mixture compositions. The forward rate constant decreases continuously with increasing isobutene/methanol ratio, while an increase in reaction rate constant is observed with an increasing amount of MtBE in

  4. Influence of Synthesis pH on Textural Properties of Carbon Xerogels as Supports for Pt/CXs Catalysts for Direct Methanol Fuel Cells

    Directory of Open Access Journals (Sweden)

    C. Alegre

    2012-01-01

    Full Text Available Carbon xerogels (CXs have been prepared by polycondensation of resorcinol and formaldehyde. Two synthesis pHs were studied in order to evaluate its influence on the electrochemical behaviour of Pt catalysts supported on previous carbon xerogels, synthesized by conventional impregnation method. Catalysts were also synthesized over a commercial carbon black (Vulcan-XC-72R for comparison purposes. Characterization techniques included nitrogen physisorption, scanning electron microscopy, and X-ray diffraction. Catalysts electrochemical activity towards the oxidation of carbon monoxide and methanol was studied by cyclic voltammetry and chronoamperometry to establish the effect of the carbon support on the catalysts performance. Commercial Pt/C catalyst (E-TEK was analyzed for comparison purposes. It was observed that the more developed and mesopore-enriched porous structure of the carbon xerogel synthesized at a higher initial pH resulted in an optimal utilization of the active phase and in an enhanced and promising catalytic activity in the electrooxidation of methanol, in comparison with commercial catalysts.

  5. Rapid, general synthesis of PdPt bimetallic alloy nanosponges and their enhanced catalytic performance for ethanol/methanol electrooxidation in an alkaline medium.

    Science.gov (United States)

    Zhu, Chengzhou; Guo, Shaojun; Dong, Shaojun

    2013-01-14

    We have demonstrated a rapid and general strategy to synthesize novel three-dimensional PdPt bimetallic alloy nanosponges in the absence of a capping agent. Significantly, the as-prepared PdPt bimetallic alloy nanosponges exhibited greatly enhanced activity and stability towards ethanol/methanol electrooxidation in an alkaline medium, which demonstrates the potential of applying these PdPt bimetallic alloy nanosponges as effective electrocatalysts for direct alcohol fuel cells. In addition, this simple method has also been applied for the synthesis of AuPt, AuPd bimetallic, and AuPtPd trimetallic alloy nanosponges. The as-synthesized three-dimensional bimetallic/trimetallic alloy nanosponges, because of their convenient preparation, well-defined sponge-like network, large-scale production, and high electrocatalytic performance for ethanol/methanol electrooxidation, may find promising potential applications in various fields, such as formic acid oxidation or oxygen reduction reactions, electrochemical sensors, and hydrogen-gas sensors. Copyright © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  6. Rapid and facile CuCl assistant synthesis of PtCu3 nanoframes as efficient catalysts for electroxidation of methanol

    Science.gov (United States)

    Bai, Lei; Bai, Yuwei

    2018-02-01

    Hollow-structured nanomaterials generally showed enhanced catalytic abilities due to their high utilization. In this work, a general method for the synthesis of PtCu3 nanoframes was reported with the employment of hexadecyltrimethylammonium chloride (CTAC), copper(I) chloride, and various kinds of platinum precursors such as K2PtCl6, H2PtCl6, and Pt(acac)2. It was revealed that the presence of CTAC was crucial for the formation of frame structures. On the one hand, CTAC could act as a structure director, and on the other hand, the galvanic replacement and etching effect of the chloride ions together with oxygen was also responsible for the formation of the frame structure. A similar effect was also evidenced in the case of hexadecyltrimethylammonium bromide. Finally, the as-obtained PtCu3 nanoframes demonstrated high catalytic abilities in the oxidation of methanol as a model reaction. [Figure not available: see fulltext.

  7. Stability studies of oxytetracycline in methanol solution

    Science.gov (United States)

    Wang, Wei; Wu, Nan; Yang, Jinghui; Zeng, Ming; Xu, Chenshan; Li, Lun; Zhang, Meng; Li, Liting

    2018-02-01

    As one kind of typical tetracycline antibiotics, antibiotic residues of oxytetracycline have been frequently detected in many environmental media. In this study, the stability of oxytetracycline in methanol solution was investigated by high-performance liquid chromatography combined with UV-vis (HPLC-UV). The results show that the stability of oxytetracycline in methanol solution is highly related to its initial concentration and the preserved temperature. Under low temperature condition, the solution was more stable than under room temperature preservation. Under the same temperature preservation condition, high concentrations of stock solutions are more stable than low concentrations. The study provides a foundation for preserving the oxytetracycline-methanol solution.

  8. Microwave Assisted Synthesis of Osmium Electrocatalysts for the Oxygen Reduction Reaction in the Absence and Presence of Aqueous Methanol

    Directory of Open Access Journals (Sweden)

    Edgar Borja-Arco

    2011-01-01

    Full Text Available Osmium electrocatalysts for the oxygen reduction reaction (ORR were prepared by microwave irradiation of Os3(CO12 at different experimental conditions. The materials obtained were structurally characterized by FT-IR, micro-Raman spectroscopy and X-ray diffraction. Their chemical compositions were obtained by EDS. The electrocatalytic properties for the oxygen reduction reaction were evaluated by rotating disk electrode measurements in 0.5 mol L-1 H2SO4, in the absence and presence of aqueous methanol. The kinetic parameters, such as Tafel slope, exchange current density, and charge transfer coefficient are reported.

  9. Low temperature photoresponse of monolayer tungsten disulphide

    Directory of Open Access Journals (Sweden)

    Bingchen Cao

    2014-11-01

    Full Text Available High photoresponse can be achieved in monolayers of transition metal dichalcogenides. However, the response times are inconveniently limited by defects. Here, we report low temperature photoresponse of monolayer tungsten disulphide prepared by exfoliation and chemical vapour deposition (CVD method. The exfoliated device exhibits n-type behaviour; while the CVD device exhibits intrinsic behaviour. In off state, the CVD device has four times larger ratio of photoresponse for laser on/off and photoresponse decay–rise times are 0.1 s (limited by our setup, while the exfoliated device has few seconds. These findings are discussed in terms of charge trapping and localization.

  10. Low-temperature preparation of pyrolytic carbon

    International Nuclear Information System (INIS)

    Kidd, R.W.; Seifert, D.A.; Browning, M.F.

    1984-01-01

    Previous studies have demonstrated that nuclear waste forms coated with chemical vapor deposited pyrolytic carbon (PyC) at about 1273 K can provide ground water leach protection. To minimize the release during coating of volatile material from the waste forms and permit the coating of waste forms with a low softening point, a study was initiated to develop parameters for the catalytic deposition of PyC at low temperatures. The parameters surveyed in a fluidized-bed coater were deposition temperatures, carbon precursors, catalyst, diluent gas, concentration, and pressure

  11. Investigations of Low Temperature Time Dependent Cracking

    Energy Technology Data Exchange (ETDEWEB)

    Van der Sluys, W A; Robitz, E S; Young, B A; Bloom, J

    2002-09-30

    The objective of this project was to investigate metallurgical and mechanical phenomena associated with time dependent cracking of cold bent carbon steel piping at temperatures between 327 C and 360 C. Boiler piping failures have demonstrated that understanding the fundamental metallurgical and mechanical parameters controlling these failures is insufficient to eliminate it from the field. The results of the project consisted of the development of a testing methodology to reproduce low temperature time dependent cracking in laboratory specimens. This methodology was used to evaluate the cracking resistance of candidate heats in order to identify the factors that enhance cracking sensitivity. The resultant data was integrated into current available life prediction tools.

  12. Ionometric determination of fluorides at low temperatures

    International Nuclear Information System (INIS)

    Kostyukova, I.S.; Ennan, A.A.; Dzerzhko, E.K.; Leivikova, A.A.

    1995-01-01

    A method for determining fluoride ions in solution at low temperatures using a solid-contact fluorine-selective electrode (FSE) has been developed. The effect of temperature (60 to -15 degrees C) on the calibration slope, potential equilibrium time, and operational stability is studied; the effect of an organic additive (cryoprotector) on the calibration slope is also studied. The temperature relationships obtained for the solid-contact FSEs allow appropriate corrections to be applied to the operational algorithm of the open-quotes Ftoringclose quotes hand-held semiautomatic HF gas analyzer for the operational temperature range of -16 to 60 degrees C

  13. Low-temperature centrifugal helium compressor

    International Nuclear Information System (INIS)

    Kawada, M.; Togo, S.; Akiyama, Y.; Wada, R.

    1974-01-01

    A centrifugal helium compressor with gas bearings, which can be operated at the temperature of liquid nitrogen, has been investigated. This compressor has the advantages that the compression ratio should be higher than the room temperature operation and that the contamination of helium could be eliminated. The outer diameter of the rotor is 112 mm. The experimental result for helium gas at low temperature shows a flow rate of 47 g/s and a compression ratio of 1.2 when the inlet pressure was 1 ata and the rotational speed 550 rev/s. The investigation is now focused on obtaining a compression ratio of 1.5. (author)

  14. Facile synthesis of palladium–graphene nanocomposites and their catalysis for electro-oxidation of methanol and ethanol

    International Nuclear Information System (INIS)

    Zhang, Yuting; Shu, Honghui; Chang, Gang; Ji, Kai; Oyama, Munetaka; Liu, Xiong; He, Yunbin

    2013-01-01

    Highlights: • Pd nanoparticles/graphene (PdNPs/graphene) was synthesized within one-step process. • Environment friendly ascorbic acid was chosen as the reductant. • The synthesized PdNPs/graphene shows superior electrocatalytic activity to both methanol and ethanol. • PdNPs/graphene shows superior electrocatalytic stability in methanol and ethanol electro-oxidation. -- Abstract: Well-dispersed Pd nanoparticles (PdNPs) supported on graphene sheets were successfully prepared by a simple one-pot process, in which the reduction of Poly Vingl Pyrrolidone-functionalized graphite oxide and Pd precursor was carried out simultaneously using ascorbic acid as a soft reductant. The Pd nanoparticles decorated graphene composite (PdNPs/PVP-graphene) was characterized by X-ray diffraction, transmission electron microscopy, and X-ray photoelectron spectroscopy. Morphology and structure characterizations directly showed that Pd nanoparticles with crystallite size of about 8.5 nm were evenly formed on graphene. Catalysis activity as in fuel cells was investigated by further electrochemical experiments including cyclic voltammograms and chronoamperometric measurements. Compared to the commercial Vulcan XC-72 supported Pd nanoparticles, PdNPs/PVP-graphene exhibits superior electrocatalytic activity and stability toward electro-oxidation of alcohols, showing its potential use as new electrode material for direct alcohol fuel cells (DAFCs)

  15. One-step synthesis of PtPdAu ternary alloy nanoparticles on graphene with superior methanol electrooxidation activity

    Energy Technology Data Exchange (ETDEWEB)

    Zhang Yuzhen; Gu Yonge; Lin Shaoxiong; Wei Jinping; Wang Zaihua [Department of Chemistry, Lanzhou University, Lanzhou 730000 (China); Wang Chunming, E-mail: wangcm@lzu.edu.cn [Department of Chemistry, Lanzhou University, Lanzhou 730000 (China); Du Yongling; Ye Weichun [Department of Chemistry, Lanzhou University, Lanzhou 730000 (China)

    2011-10-01

    Highlights: > PtPdAu nanoparticles were synthesized on graphene sheets via chemical reduction method. > The prepared PtPdAu nanoparticles were ternary alloy with fcc structure. > The catalyst exhibited superior catalytic activity and stability for MOR in alkaline. - Abstract: Well-dispersed PtPdAu ternary alloy nanoparticles were synthesized on graphene sheets via a simple one-step chemical reduction method in ethylene glycol (EG) and water system, in which EG served as both reductive and dispersing agent. The electrocatalytic activity of PtPdAu/G was tested by methanol oxidation reaction (MOR). The catalyst was further characterized by transmission electron microscopy (TEM), energy dispersive X-ray spectroscopy (EDX), X-ray photoelectron spectroscopy (XPS) and X-ray diffraction (XRD), which indicated that the as-synthesized PtPdAu nanoparticles with alloy structures were successfully dispersed on the graphene sheets. Electrocatalytic properties of the catalyst for MOR in alkaline have been investigated by cyclic voltammetry (CV), chronoamperometry and Tafel curves. The electrocatalytic activity and stability of PtPdAu/G were superior to PtPd/G, PtAu/G and Pt/G. In addition, the anodic peak current on PtPdAu/G catalyst was proportional to the concentration of methanol in the range of 0.05-1.00 M. This study implies that the prepared catalyst have great potential applications in fuel cells.

  16. Effect of hierarchical meso–macroporous alumina-supported copper catalyst for methanol synthesis from CO2 hydrogenation

    International Nuclear Information System (INIS)

    Witoon, Thongthai; Bumrungsalee, Sittisut; Chareonpanich, Metta; Limtrakul, Jumras

    2015-01-01

    Highlights: • CO 2 hydrogenation over Cu-loaded unimodal and hierarchical alumina catalysts. • Cu-loaded hierarchical catalyst exhibited higher methanol selectivity and stability. • The presence of macropores reduced the probability of side reaction. - Abstract: Effects of pore structures of alumina on the catalytic performance of copper catalysts for CO 2 hydrogenation were investigated. Copper-loaded hierarchical meso–macroporous alumina (Cu/HAl) catalyst exhibited no significant difference in terms of CO 2 conversion with copper-loaded unimodal mesoporous alumina (Cu/UAl) catalyst. However, the selectivity to methanol and dimethyl ether of the Cu/HAl catalyst was much higher than that of the Cu/UAl catalyst. This was attributed to the presence of macropores which diminished the occurrence of side reaction by the shortening the mesopores diffusion path length. The Cu/HAl catalyst also exhibited much higher stability than the Cu/UAl catalyst due to the fast diffusion of water out from the catalyst pellets, alleviating the oxidation of metallic copper to CuO

  17. In Situ Synthesis and Characterization of Polyethyleneimine-Modified Carbon Nanotubes Supported PtRu Electrocatalyst for Methanol Oxidation

    Directory of Open Access Journals (Sweden)

    Xi Geng

    2015-01-01

    Full Text Available PtRu bimetallic nanoparticles were successfully synthesized on polyethyleneimine- (PEI- functionalized multiwalled carbon nanotubes (MWCNTs via an effective and facile polyol reduction approach. Noncovalent surface modification of MWCNTs with PEI was confirmed by FTIR and zeta potential measurements. The morphology, crystalline structure, and composition of the hybrid material were characterized by transmission electron microscopy (TEM, scanning electron microscopy (SEM, X-ray powder diffraction (XRD, and energy dispersive X-ray spectroscopy (EDX, respectively. According to SEM and TEM observations, PtRu nanoparticles with narrow size distribution were homogeneously deposited on PEI-MWCNTs. Cyclic voltammetry tests demonstrated that the as-prepared PtRu/PEI-MWCNTs nanocomposite had a large electrochemical surface area and exhibited enhanced electrocatalytic activity towards methanol oxidation in comparison with oxidized MWCNTs as catalyst support. PEI-functionalized CNTs, as useful building blocks for the assembly of Pt-based electrocatalyst, may have great potential for applications such as direct methanol fuel cell (DMFC.

  18. Facile and Rapid Synthesis of Ultrafine PtPd Bimetallic Nanoparticles and Their High Performance toward Methanol Electrooxidation

    Directory of Open Access Journals (Sweden)

    Tiantian Xia

    2014-01-01

    Full Text Available Uniform and sub-10 nm size bimetallic PtPd nanoparticles (NPs have been synthesized via a simple and facile method without using any surfactants at an ambient temperature. As a green and clean reductive agent, ascorbic acid (AA was employed for the coreduction of K2PtCl4 and K2PdCl4 in aqueous solution. The morphology, composition, and structure of PtPd NPs had been characterized by transmission electron microscopy (TEM, field emission high resolution transmission electron microscopy (FE-HRTEM, energy dispersive spectroscopy (EDS, X-ray diffraction (XRD, and X-ray photoelectron spectroscope (XPS. Comparing with both the monometallic Pt and Pd, the as-prepared alloy nanoparticles show superior electrocatalytic activity and better tolerance against poisoning by intermediates generated during methanol electrooxidation, which makes them a promising electrocatalysts for direct methanol fuel cells (DMFCs. Meanwhile, the green and simple approach could be easily extended to the manufacture of bimetallic or trimetallic alloy nanomaterials.

  19. Optimization of the synthesis of SAPO-11 for the methylation of naphthalene with methanol by varying templates and template content

    International Nuclear Information System (INIS)

    Wang, Xiaoxiao; Zhang, Wei; Zhao, Liangfu; Xiang, Hongwei; Guo, Shaoqing

    2013-01-01

    SAPO-11 zeolites were successfully synthesized by using three different templates (diethylamine (DEA), di-n-propylamine (DPA) and di-isopropylamine (DIPA)) and varying DPA contents (nDPA/Al 2 O 3 = 0.8, 1.2, 1.6 and 2.0) under hydrothermal conditions. The samples were characterized by powder X-ray diffractometry (XRD), scanning electron microscopy (SEM), N 2 adsorption-desorption, temperature programmed desorption of ammonia (NH 3 -TPD) and 29 Si magic angle spinning (MAS) nuclear magnetic resonance (NMR). The samples were also evaluated towards the methylation of naphthalene with methanol to produce 2,6-dimethylnaphthalene (2,6-DMN). XRD results indicated that the directing effect of the different templates for AEL (Aluminophosphate-ELeven) structure decreased in the order DPA > DEA > DIPA and the most suitable DPA content was nDPA/Al 2 O 3 = 1.2. N 2 adsorption-desorption results showed that SAPO-11(DPA,1.2) exhibited the broadest pore size distribution, the highest BET specific surface area and the largest pore volume among all the SAPO-11 samples. SAPO-11(DPA,1.2) exhibited high catalytic performances in the methylation of naphthalene due to its high crystallinity, high external surface and broad pore size distribution. The pore structure of SAPO-11 zeolite, rather than its acidity, played an important role in achieving high catalytic performances in the methylation of naphthalene with methanol. (author)

  20. Nitrous oxide emissions at low temperatures

    International Nuclear Information System (INIS)

    Martikainen, P.J.

    2002-01-01

    Microbial processes in soil are generally stimulated by temperature, but at low temperatures there are anomalies in the response of microbial activities. Soil physical-chemical characteristics allow existence of unfrozen water in soil also at temperatures below zero. Therefore, some microbial activities, including those responsible for nitrous oxide (N 2 0) production, can take place even in 'frozen' soil. Nitrous oxide emissions during winter are important even in boreal regions where they can account for more than 50% of the annual emissions. Snow pack therefore has great importance for N 2 0 emissions, as it insulates soil from the air allowing higher temperatures in soil than in air, and possible changes in snoav cover as a result of global warming would thus affect the N 2 0 emission from northern soils. Freezing-thawing cycles highly enhance N 2 0 emissions from soil, probably because microbial nutrients, released from disturbed soil aggregates and lysed microbial cells, support microbial N 2 0 production. However, the overall interactions between soil physics, chemistry, microbiology and N 2 0 production at low temperatures, including effects of freezing-thawing cycles, are still poorly known. (au)

  1. Efficient prepreg recycling at low temperatures

    Science.gov (United States)

    Pannkoke, Kord; Oethe, Marcus; Busse, Jürgen

    When manufacturing fibre reinforced plastics engineers are still confronted with a lack of experience concerning efficient recycling methods for prepreg cutting waste. Normally, the prepregs are cured and subsequently milled to use them as a filler material for polymers. However, this method is expensive and it is difficult to find applications for the milled FRP. An alternative method to recycle CFRP prepregs will be presented in this paper. Cutting the uncured prepreg waste was done by means of a saw mill which was cooled down to low temperatures. Working temperatures of -30°C are sufficient to harden the uncured resin and to achieve cuttable prepregs. Furthermore, post-curing during the cutting process is avoided with this technique. The result is a `cotton'-like matted structure with random fibre orientation and fibre length distribution. Subsequent curing was done by means of a press and an autoclave, respectively. It will be shown by means of tension and bending tests that low-temperature cutting of uncured prepregs is a way to partly conserve the high valuation of FRP during recycling. Furthermore, it offers possibilities for various applications.

  2. Measurement of low-temperature specific heat

    International Nuclear Information System (INIS)

    Stewart, G.R.

    1983-01-01

    The measurement of low-temperature specific heat (LTSH) (0.1 K< T<60 K) has seen a number of breakthroughs both in design concepts and instrumentation in the last 15 years: particularly in small sample calorimetry. This review attempts to provide an overview of both large and small sample calorimetry techniques at temperatures below 60 K, with sufficient references to enable more detailed study. A comprehensive review is made of the most reliable measurements of the LTSH of 84 of the elements to illustrate briefly some of the problems of measurements and analysis, as well as to provide additional references. More detail is devoted to three special areas of low-temperature calorimetry that have seen rapid development recently: (1) measurement of the specific heat of highly radioactive samples, (2) measurement of the specific heat of materials in high magnetic fields (18 T), and (3) measurement of the specific heat of very small (100 μg) samples. The review ends with a brief discussion of the frontier research currently underway on microcalorimetry for nanogram sample weights

  3. Extreme low temperature tolerance in woody plants

    Directory of Open Access Journals (Sweden)

    George Richard Strimbeck

    2015-10-01

    Full Text Available Woody plants in boreal to arctic environments and high mountains survive prolonged exposure to temperatures below -40˚C and minimum temperatures below -60˚C, and laboratory tests show that many of these species can also survive immersion in liquid nitrogen at -196˚C. Studies of biochemical changes that occur during acclimation, including recent proteomic and metabolomic studies, have identified changes in carbohydrate and compatible solute concentrations, membrane lipid composition, and proteins, notably dehydrins, that may have important roles in survival at extreme low temperature. Consideration of the biophysical mechanisms of membrane stress and strain lead to the following hypotheses for cellular and molecular mechanisms of survival at extreme low temperature: 1. Changes in lipid composition stabilize membranes at temperatures above the lipid phase transition temperature (-20 to 30˚C, preventing phase changes that result in irreversible injury. 2. High concentrations of oligosaccharides promote vitrification or high viscosity in the cytoplasm in freeze-dehydrated cells, which would prevent deleterious interactions between membranes. 3. Dehydrins bind membranes and further promote vitrification or act stearically to prevent membrane-membrane interactions.

  4. Computational Chemistry of Cyclopentane Low Temperature Oxidation

    KAUST Repository

    El Rachidi, Mariam; Zá dor, Judit; Sarathy, Mani

    2015-01-01

    reactions occurring during low-temperature cyclopentane combustion using theoretical chemical kinetics. The reaction pathways of the cyclopentyl + O2 adduct is traced to alkylhydroperoxide, cyclic ether, β-scission and HO2 elimination products. The calculations are carried out at the UCCSD(T)-F12b/cc-pVTZ-F12//M06-2X/6-311++G(d,p) level of theory. The barrierless entrance channel is treated using variable-reaction-coordinate transition state theory (VRC-TST) at the CASPT2(7e,6o) level of theory, including basis set, geometry relaxation and ZPE corrections. 1-D time-dependent multiwell master equation analysis is used to determine pressure-and temperature-dependent rate parameters of all investigated reactions. Tunneling corrections are included using Eckart barriers. Comparison with cyclohexane is used to elucidate the effect of ring size on the low temperature reactivity of naphthenes. The rate coefficients reported herein are suitable for use in cyclopentane and methylcyclopentane combustion models, even below ~900 K, where ignition is particularly sensitive to these pressure-dependent values.

  5. Production of BaAl_2O_4 doped with Eu"3"+ in low temperature: research of the influence of the synthesis route, temperature and calcination time in the optical properties

    International Nuclear Information System (INIS)

    Gomes, Manasses Almeida

    2017-01-01

    In this work, the synthesis condition (complexing agent and temperature and time of calcination) were studied aiming to produce BaAl_2O_4 samples in the ferroelectric hexagonal phase. Pure and Eu"3"+ - doped samples were produced and its luminescent properties were investigated. BaAl_2O_4 was prepared using several thermal treatment conditions, via an alternative sol-gel route, using coconut water or PVA as the complexing agents. The sample production at 600 °C/5h is quite interesting, since to date the lowest calcination temperatures found in the literature was 650 ° C using reagents with high degree of toxicity DTA / TG measurements indicated a possible start of the crystallization of the material at approximately 600 ° C, and the X-ray powder diffraction (XRD) confirm the formation of the desired phase of the calcined barium aluminate at that temperature. The results of the Rietveld refinements showed the occurrence of secondary phase in the samples produced at 600 ° C / 5h, presenting 5% of phase Ba(NO_3)_2, while single phase was found for samples calcined at 1200 ° C for 2 and 5h. Analysis of the diffractogram by the Scherrer equation showed smaller crystallite size for samples calcified at 600 °C/5h, but apparently with a lower degree of crystallinity than the sample prepared at 1200 ° C/ 2 and 5h. The photoluminescence measurements showed that the emission spectra of the samples have great dependence on the times, temperatures and complexing agents used. In particular, samples calcined at 600 ° C have very different characteristics with regard to the probabilities of emissions associated with Eu"3"+ when compared with samples produced at higher temperatures. Differences observed in the spectra of samples produced via different complexing agents are possibly due to defects created in the materials by impurities present in the coconut water. Samples produced using PVA present sites with higher symmetry, which was evidenced by a lower relative emission

  6. Methanogenesis at low temperatures by microflora of tundra wetland soil.

    Science.gov (United States)

    Kotsyurbenko, O R; Nozhevnikova, A N; Soloviova, T I; Zavarzin, G A

    1996-01-01

    Active methanogenesis from organic matter contained in soil samples from tundra wetland occurred even at 6 degrees C. Methane was the only end product in balanced microbial community with H2/CO2 as a substrate, besides acetate was produced as an intermediate at temperatures below 10 degrees C. The activity of different microbial groups of methanogenic community in the temperature range of 6-28 degrees C was investigated using 5% of tundra soil as inoculum. Anaerobic microflora of tundra wetland fermented different organic compounds with formation of hydrogen, volatile fatty acids (VFA) and alcohols. Methane was produced at the second step. Homoacetogenic and methanogenic bacteria competed for such substrates as hydrogen, formate, carbon monoxide and methanol. Acetogens out competed methanogens in an excess of substrate and low density of microbial population. Kinetic analysis of the results confirmed the prevalence of hydrogen acetogenesis on methanogenesis. Pure culture of acetogenic bacteria was isolated at 6 degrees C. Dilution of tundra soil and supply with the excess of substrate disbalanced the methanoigenic microbial community. It resulted in accumulation of acetate and other VFA. In balanced microbial community obviously autotrophic methanogens keep hydrogen concentration below a threshold for syntrophic degradation of VFA. Accumulation of acetate- and H2/CO2-utilising methanogens should be very important in methanogenic microbial community operating at low temperatures.

  7. The Low Temperature Microgravity Physics Experiments Project

    Science.gov (United States)

    Holmes, Warren; Lai, Anthony; Croonquist, Arvid; Chui, Talso; Eraker, J. H.; Abbott, Randy; Mills, Gary; Mohl, James; Craig, James; Balachandra, Balu; hide

    2000-01-01

    The Low Temperature Microgravity Physics Facility (LTMPF) is being developed by NASA to provide long duration low temperature and microgravity environment on the International Space Station (ISS) for performing fundamental physics investigations. Currently, six experiments have been selected for flight definition studies. More will be selected in a two-year cycle, through NASA Research Announcement. This program is managed under the Low Temperature Microgravity Physics Experiments Project Office at the Jet Propulsion Laboratory. The facility is being designed to launch and returned to earth on a variety of vehicles including the HII-A and the space shuttle. On orbit, the facility will be connected to the Exposed Facility on the Japanese Experiment Module, Kibo. Features of the facility include a cryostat capable of maintaining super-fluid helium at a temperature of 1.4 K for 5 months, resistance thermometer bridges, multi-stage thermal isolation system, thermometers capable of pico-Kelvin resolution, DC SQUID magnetometers, passive vibration isolation, and magnetic shields with a shielding factor of 80dB. The electronics and software architecture incorporates two VME buses run using the VxWorks operating system. Technically challenging areas in the design effort include the following: 1) A long cryogen life that survives several launch and test cycles without the need to replace support straps for the helium tank. 2) The minimization of heat generation in the sample stage caused by launch vibration 3) The design of compact and lightweight DC SQUID electronics. 4) The minimization of RF interference for the measurement of heat at pico-Watt level. 5) Light weighting of the magnetic shields. 6) Implementation of a modular and flexible electronics and software architecture. The first launch is scheduled for mid-2003, on an H-IIA Rocket Transfer Vehicle, out of the Tanegashima Space Center of Japan. Two identical facilities will be built. While one facility is onboard

  8. Radically Different Kinetics at Low Temperatures

    Science.gov (United States)

    Sims, Ian

    2014-06-01

    The use of the CRESU (Cinétique de Réaction en Ecoulement Supersonique Uniforme, or Reaction Kinetics in Uniform Supersonic Flow) technique coupled with pulsed laser photochemical kinetics methods has shown that reactions involving radicals can be very rapid at temperatures down to 10 K or below. The results have had a major impact in astrochemistry and planetology, as well as proving an exacting test for theory. The technique has also been applied to the formation of transient complexes of interest both in atmospheric chemistry and combustion. Until now, all of the chemical reactions studied in this way have taken place on attractive potential energy surfaces with no overall barrier to reaction. The F + H2 {→} HF + H reaction does possess a substantial energetic barrier ({\\cong} 800 K), and might therefore be expected to slow to a negligible rate at very low temperatures. In fact, this H-atom abstraction reaction does take place efficiently at low temperatures due entirely to tunneling. I will report direct experimental measurements of the rate of this reaction down to a temperature of 11 K, in remarkable agreement with state-of-the-art quantum reactive scattering calculations by François Lique (Université du Havre) and Millard Alexander (University of Maryland). It is thought that long chain cyanopolyyne molecules H(C2)nCN may play an important role in the formation of the orange haze layer in Titan's atmosphere. The longest carbon chain molecule observed in interstellar space, HC11N, is also a member of this series. I will present new results, obtained in collaboration with Jean-Claude Guillemin (Ecole de Chimie de Rennes) and Stephen Klippenstein (Argonne National Labs), on reactions of C2H, CN and C3N radicals (using a new LIF scheme by Hoshina and Endo which contribute to the low temperature formation of (cyano)polyynes. H. Sabbah, L. Biennier, I. R. Sims, Y. Georgievskii, S. J. Klippenstein, I. W. M. Smith, Science 317, 102 (2007). S. D. Le Picard, M

  9. Novel synthesis of methoxymethyl benzene by electrochemical coupling reaction of toluene with methanol in ionic liquid media.

    Science.gov (United States)

    Chen, Fengtao; Wang, Bo; Ma, Hongzhu

    2009-06-15

    An ionic liquid (1-butyl-3-methylimidazolium dibutyl phosphate) was prepared and characterized by cyclic voltammogram (CV) and Fourier transform infrared spectrometer (FT-IR). The ionic liquid exhibited good catalytic activity for the electrochemical reaction of toluene with methanol assisted with a pair of porous graphite plane electrodes and product yield higher than 56% was observed. In addition, the electrochemical process was detected by UV-vis spectrum and the products were analyzed by gas chromatography/mass spectrometry (GC/MS). According to the experimental results, a possible free radical reaction mechanism was proposed. It may be concluded that a simply and feasible electrochemical coupling reaction at room temperature and atmospheric pressure may be possible. Compared with methyl tert-butyl ether (MTBE), the main product (methoxymethyl benzene) used as booster to improve fuel combustion was also studied.

  10. Automatic synthesis of [11C]NKY-722 with high specific activity, using anhydrous [11C] methanol as a precursor

    International Nuclear Information System (INIS)

    Suzuki, Kazutoshi; Inoue, Osamu; Itoh, Takashi; Nemoto, Kazuyoshi; Oosumi, Seimei; Miwa, Soichi.

    1992-01-01

    3-(4-allyl-1-piperazinyl)-2,2-dimethylpropyl methyl 1,4-dihydro-2,6-dimethyl- 4-(3-nitrophenyl)-3,5-pyridine dicarboxylate (NKY-722) was labeled with carbon-11 using anhydrous [ 11 C] methanol. Using a computer controlled equipment, a few GBq of [ 11 C] NKY-722 with the specific activity of 120 - 180 GBq/μmol could by synthesized at the radiochemical purity of > 99% in 10 ml of physiological saline containing Polysolvate-80 (1.5 vol%) and ethyl alcohol (0.75 vol%). Preliminary PET experiments using rats and a rhesus monkey have bee done, and very low accumulation of the compound into the brain, however comparatively higher accumulation in the heart were observed. (author)

  11. Synthesis of Pt-Ru PSB-Py catalysis by {gamma}-irradiation and their electrocatalytic efficiency for methanol oxidation

    Energy Technology Data Exchange (ETDEWEB)

    Yoon, Jung Ah; Sim, Kwang Sik; Choi, Seong Ho [Hannam University, Daejeon (Korea, Republic of); Jung, Sung Hee [Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of)

    2009-09-15

    We report here that deposition of Pt-Ru catalysis on the surface of core-shell conductive balls by radiation-chemical reduction of Pt and Ru ions, in order to use as catalysis in a fuel cell. The poly(styrene-co-4-vinylphenylboronic acid)-pyrrole (PSB-Py) with core-shell structure was obtained by in situ polymerization of pyrrole in the presence of the poly(styrene-co-4-vinylphenylboronic acid) (PSB). Subsequently, Pt-Ru catalysis were deposited onto PSB-Py ball by {gamma}-irradiation, in the presence/absence of poly(vinypyrolidone) (PVP) to prepare electrocatalysis for a fuel cell. The catalytic efficiency of Pt-Ru PSB-Py catalyst was examined for carbon monoxide (CO) stripping and methanol oxidation.

  12. Synthesis of Pt-Ru PSB-Py catalysis by γ-irradiation and their electrocatalytic efficiency for methanol oxidation

    International Nuclear Information System (INIS)

    Yoon, Jung Ah; Sim, Kwang Sik; Choi, Seong Ho; Jung, Sung Hee

    2009-01-01

    We report here that deposition of Pt-Ru catalysis on the surface of core-shell conductive balls by radiation-chemical reduction of Pt and Ru ions, in order to use as catalysis in a fuel cell. The poly(styrene-co-4-vinylphenylboronic acid)-pyrrole (PSB-Py) with core-shell structure was obtained by in situ polymerization of pyrrole in the presence of the poly(styrene-co-4-vinylphenylboronic acid) (PSB). Subsequently, Pt-Ru catalysis were deposited onto PSB-Py ball by γ-irradiation, in the presence/absence of poly(vinypyrolidone) (PVP) to prepare electrocatalysis for a fuel cell. The catalytic efficiency of Pt-Ru PSB-Py catalyst was examined for carbon monoxide (CO) stripping and methanol oxidation

  13. Optimization of the synthesis of SAPO-11 for the methylation of naphthalene with methanol by varying templates and template content

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Xiaoxiao [University of Chinese Academy of Sciences, Beijing (China); Zhang, Wei; Zhao, Liangfu; Xiang, Hongwei, E-mail: zw7234@sxicc.ac.cn, E-mail: lfzhao@sxicc.ac.cn [Institute of Coal Chemistry, Chinese Academy of Sciences, Taiyuan (China); Guo, Shaoqing [Taiyuan University of Science and Technology, Taiyuan (China)

    2013-07-15

    SAPO-11 zeolites were successfully synthesized by using three different templates (diethylamine (DEA), di-n-propylamine (DPA) and di-isopropylamine (DIPA)) and varying DPA contents (nDPA/Al{sub 2}O{sub 3} = 0.8, 1.2, 1.6 and 2.0) under hydrothermal conditions. The samples were characterized by powder X-ray diffractometry (XRD), scanning electron microscopy (SEM), N{sub 2} adsorption-desorption, temperature programmed desorption of ammonia (NH{sub 3} -TPD) and {sup 29}Si magic angle spinning (MAS) nuclear magnetic resonance (NMR). The samples were also evaluated towards the methylation of naphthalene with methanol to produce 2,6-dimethylnaphthalene (2,6-DMN). XRD results indicated that the directing effect of the different templates for AEL (Aluminophosphate-ELeven) structure decreased in the order DPA > DEA > DIPA and the most suitable DPA content was nDPA/Al{sub 2}O{sub 3} = 1.2. N{sub 2} adsorption-desorption results showed that SAPO-11(DPA,1.2) exhibited the broadest pore size distribution, the highest BET specific surface area and the largest pore volume among all the SAPO-11 samples. SAPO-11(DPA,1.2) exhibited high catalytic performances in the methylation of naphthalene due to its high crystallinity, high external surface and broad pore size distribution. The pore structure of SAPO-11 zeolite, rather than its acidity, played an important role in achieving high catalytic performances in the methylation of naphthalene with methanol. (author)

  14. Low temperature distillation of coal, shale, etc

    Energy Technology Data Exchange (ETDEWEB)

    1938-08-12

    A process is disclosed for the low temperature distillation of solid carbonaceous fuels, such as coal, lignite, shale or the like, which comprises feeding or supplying the comminuted fuel in the form of a layer of shallow depth to drying and distilling zones in succession moving the fuel forward through the zones, submitting it to progressively increasing nonuniform heating therein by combustion gases supplied to the distillation zone and traveling thence to the drying zone, the gases heating the distillation zone indirectly and the drying zone both indirectly and then directly such that the fuel retains its solid discrete form during substantially the whole of its travel through the drying and distillation zones, subjecting the fuel for a portion of its travel to a zigzag ploughing and propelling movement on a heated sole, and increasing the heating so as to cause fusion of the fuel immediately prior to its discharge from the distillation zone.

  15. On Low-temperature Polyamorphous transformations

    International Nuclear Information System (INIS)

    Bakay, A.S.

    2006-01-01

    A theory of polyamorphous transformations in glasses is constructed in the framework of a model of heterophase fluctuations with allowance for the fact that a glass inherits the short- and intermediate-range order from the liquid. A multicomponent order parameter describing the concentration of fluctuons with different types of short-range order is introduced, along with the concepts of isoconfigurational and non-isoconfigurational transitions in the glass. Taking the nonergodicity, nonequilibrium, and multiplicity of structural states of a glass into account leads to a kinetic criterion of observability of polyamorphism of a glass. As an example, a theory is constructed for the low-temperature first-order phase transition in an orientational glass based on doped fullerite. The relaxation processes of this system are described, including the subsystem of tunneling states. The possibility of a hierarchy of polyamorphous transformations in a glass is discussed

  16. Shock waves in helium at low temperatures

    International Nuclear Information System (INIS)

    Liepmann, H.W.; Torczynski, J.R.

    1986-01-01

    Results are reported from studies of the properties of low temperature He-4 using shock waves as a probe. Ideal shock tube theory is used to show that sonic speeds of Mach 40 are attainable in He at 300 K. Viscosity reductions at lower temperatures minimize boundary layer effects at the side walls. A two-fluid model is described to account for the phase transition which He undergoes at temperatures below 2.2 K, after which the quantum fluid (He II) and the normal compressed superfluid (He I) coexist. Analytic models are provided for pressure-induced shocks in He I and temperature-induced shock waves (called second sound) which appear in He II. The vapor-fluid interface of He I is capable of reflecting second and gasdynamic sound shocks, which can therefore be used as probes for studying phase transitions between He I and He II. 17 references

  17. Preparation of silver nanoparticles at low temperature

    Energy Technology Data Exchange (ETDEWEB)

    Mishra, Mini, E-mail: mishramini5@gmail.com [Centre of Environmental Science, Department of Botany, University of Allahabad, Allahabad, U.P. (India); Chauhan, Pratima, E-mail: mangu167@yahoo.co.in [Department of Physics, University of Allahabad, Allahabad U.P. (India)

    2016-04-13

    Silver from ancient time is used as antimicrobial agent in the bulk form but now with the advancement in nanotechnology silver in the form of nanoparticles shown potential effect against microbes which make us easy to fight with many diseases plants and animals. In this work silver nanoparticles were synthesized by chemical routes using sodium borohydride as reducing agent at low temperature. The particles were characterized through UV-Visible spectroscopy as well as X-Ray Diffraction. The UV-visible spectra of silver nanoparticles exhibited absorption at 425 cm; the crystallite size of the particles is between 19nm to 39nm. EDAX graph shows two peaks of silver and oxygen. Water absorbed by silver nanoparticles was removed by the calcinations.

  18. Preparation of silver nanoparticles at low temperature

    International Nuclear Information System (INIS)

    Mishra, Mini; Chauhan, Pratima

    2016-01-01

    Silver from ancient time is used as antimicrobial agent in the bulk form but now with the advancement in nanotechnology silver in the form of nanoparticles shown potential effect against microbes which make us easy to fight with many diseases plants and animals. In this work silver nanoparticles were synthesized by chemical routes using sodium borohydride as reducing agent at low temperature. The particles were characterized through UV-Visible spectroscopy as well as X-Ray Diffraction. The UV-visible spectra of silver nanoparticles exhibited absorption at 425 cm; the crystallite size of the particles is between 19nm to 39nm. EDAX graph shows two peaks of silver and oxygen. Water absorbed by silver nanoparticles was removed by the calcinations.

  19. Desalination by very low temperature nuclear heat

    International Nuclear Information System (INIS)

    Saari, Risto

    1977-01-01

    A new sea water desalination method has been developed: Nord-Aqua Vacuum Evaporation, which utilizes waste heat at a very low temperature. The requisite vacuum is obtained by the aid of a barometric column and siphon, and the dissolved air is removed from the vacuum by means of water flows. According to test results from a pilot plant, the process is operable if the waste heat exists at a temperature 7degC higher than ambient. The pumping energy which is then required is 9 kcal/kg, or 1.5% of the heat of vaporization of water. Calculations reveal that the method is economically considerably superior to conventional distilling methods. (author)

  20. Recrystallization of magnesium deformed at low temperatures

    International Nuclear Information System (INIS)

    Fromageau, R.; Pastol, J.L.; Revel, G.

    1978-01-01

    The recrystallization of magnesium was studied after rolling at temperatures ranging between 248 and 373 K. For zone refined magnesium the annealing behaviour as observed by electrical resistivity measurements showed two stages at about 250 K and 400 K due respectively to recrystallization and grain growth. The activation energy associated with the recrystallization stage was 0.75 +- 0.01 eV. In less pure magnesium, with nominal purity 99.99 and 99.9%, the recrystallization stage was decomposed into two substages. Activation energies were determined in relation with deformation temperature and purity. The magnesium of intermediate purity (99.99%) behaved similarly to the lowest purity metal when it was deformed at high temperature and to the purest magnesium when the deformation was made at low temperature. This behaviour was discussed in connection with the theories of Luecke and Cahn. (Auth.)

  1. Low temperature distillation of powdered materials

    Energy Technology Data Exchange (ETDEWEB)

    1929-04-11

    In the low temperature distillation of powdered material such as coal, brown coal, or oil shale, dust carried by the gases and vapors is precipitated by supplying liquid hydrocarbons to the effluent gases, for example, to a dust remover through which the distillates pass. The material is supplied through a hopper and moved through a retort by a worm feed, and is discharged into a sump. Scavenging gases such as steam may be introduced through a pipe. Two conveyor worms moving in opposite directions are provided in an outlet conduit which may be surrounded by a cooling jacket. Heavy hydrocarbons condense on the walls of the conduit and on the conveyor worms and serve as dust catchers for the distillates, the lighted volatiles escaping through an outlet. The high boiling point oils flow back to and are cracked in the retort. Oils such as tar oils may be sprayed into the conduit or directly adjacent the entry of the material from feeding hopper.

  2. Installation for low temperature vapor explosion experiment

    International Nuclear Information System (INIS)

    Nilsuwankosit, Sunchai; Archakositt, Urith

    2000-01-01

    A preparation for the experiment on the low temperature vapor explosion was planned at the department of Nuclear Technology, Chulalongkorn University, Thailand. The objective of the experiment was to simulate the interaction between the molten fuel and the volatile cooling liquid without resorting to the high temperature. The experiment was expected to involve the injection of the liquid material at a moderate temperature into the liquid material with the very low boiling temperature in order to observe the level of the pressurization as a function of the temperatures and masses of the applied materials. For this purpose, the liquid nitrogen and the water were chosen as the coolant and the injected material for this experiment. Due to the size of the installation and the scale of the interaction, only lumped effect of various parameters on the explosion was expected from the experiment at this initial stage. (author)

  3. Biomedical applications using low temperature plasma technology

    International Nuclear Information System (INIS)

    Dai Xiujuan; Jiang Nan

    2006-01-01

    Low temperature plasma technology and biomedicine are two different subjects, but the combination of the two may play a critical role in modern science and technology. The 21 st century is believed to be a biotechnology century. Plasma technology is becoming a widely used platform for the fabrication of biomaterials and biomedical devices. In this paper some of the technologies used for material surface modification are briefly introduced. Some biomedical applications using plasma technology are described, followed by suggestions as to how a bridge between plasma technology and biomedicine can be built. A pulsed plasma technique that is used for surface functionalization is discussed in detail as an example of this kind of bridge or combination. Finally, it is pointed out that the combination of biomedical and plasma technology will be an important development for revolutionary 21st century technologies that requires different experts from different fields to work together. (authors)

  4. Low-temperature geothermal resources of Washington

    Energy Technology Data Exchange (ETDEWEB)

    Schuster, J.E. [Washington State Dept. of Natural Resources, Olympia, WA (United States). Div. of Geology and Earth Resources; Bloomquist, R.G. [Washington State Energy Office, Olympia, WA (United States)

    1994-06-01

    This report presents information on the location, physical characteristics, and water chemistry of low-temperature geothermal resources in Washington. The database includes 941 thermal (>20C or 68F) wells, 34 thermal springs, lakes, and fumaroles, and 238 chemical analyses. Most thermal springs occur in the Cascade Range, and many are associated with stratovolcanoes. In contrast, 97 percent of thermal wells are located in the Columbia Basin of southeastern Washington. Some 83.5 percent are located in Adams, Benton, Franklin, Grant, Walla Walla, and Yakima Counties. Yakima County, with 259 thermal wells, has the most. Thermal wells do not seem to owe their origin to local sources of heat, such as cooling magma in the Earth`s upper crust, but to moderate to deep circulation of ground water in extensive aquifers of the Columbia River Basalt Group and interflow sedimentary deposits, under the influence of a moderately elevated (41C/km) average geothermal gradient.

  5. Low-temperature glycerolysis of avocado oil

    Science.gov (United States)

    Satriana, Arpi, Normalina; Supardan, Muhammad Dani; Gustina, Rizka Try; Mustapha, Wan Aida Wan

    2018-04-01

    Glycerolysis can be a useful technique for production of mono- and diacylglycerols from triacylglycerols present in avocado oil. In the present work, the effect of catalyst and co-solvent concentration on low-temperature glycerolysis of avocado oil was investigated at 40oC of reaction temperature. A hydrodynamic cavitation system was used to enhance the miscibility of the oil and glycerol phases. NaOH and acetone were used as catalyst and co-solvent, respectively. The experimental results showed that the catalyst and co-solvent concentration affected the glycerolysis reaction rate. The catalyst concentration of 1.5% and co-solvent concentration of 300% were the optimised conditions. A suitable amount of NaOH and acetone must be added to achieve an optimum of triacylglycerol conversion.

  6. Low Temperature Waste Immobilization Testing Vol. I

    Energy Technology Data Exchange (ETDEWEB)

    Russell, Renee L.; Schweiger, Michael J.; Westsik, Joseph H.; Hrma, Pavel R.; Smith, D. E.; Gallegos, Autumn B.; Telander, Monty R.; Pitman, Stan G.

    2006-09-14

    The Pacific Northwest National Laboratory (PNNL) is evaluating low-temperature technologies to immobilize mixed radioactive and hazardous waste. Three waste forms—alkali-aluminosilicate hydroceramic cement, “Ceramicrete” phosphate-bonded ceramic, and “DuraLith” alkali-aluminosilicate geopolymer—were selected through a competitive solicitation for fabrication and characterization of waste-form properties. The three contractors prepared their respective waste forms using simulants of a Hanford secondary waste and Idaho sodium bearing waste provided by PNNL and characterized their waste forms with respect to the Toxicity Characteristic Leaching Procedure (TCLP) and compressive strength. The contractors sent specimens to PNNL, and PNNL then conducted durability (American National Standards Institute/American Nuclear Society [ANSI/ANS] 16.1 Leachability Index [LI] and modified Product Consistency Test [PCT]) and compressive strength testing (both irradiated and as-received samples). This report presents the results of these characterization tests.

  7. Zirconia thin film preparation by wet chemical methods at low temperature

    NARCIS (Netherlands)

    Popovici, M.; Graaf, de J.; Verschuuren, M.A.; Graat, P.C.J.; Verheijen, M.A.

    2010-01-01

    In this study the preparation of zirconia thin films with a high refractive index at low temperature is aimed for. Two non-hydrolytic type approaches of wet chemical synthesis are presented. Both by sol–gel and colloid chemistry, highly transmissive, smooth thin films of zirconia cubic and/or

  8. The effect of low temperature cryocoolers on the development of low temperature superconducting magnets

    International Nuclear Information System (INIS)

    Green, Michael A.

    2000-01-01

    The commercial development of reliable 4 K cryocoolers improves the future prospects for magnets made from low temperature superconductors (LTS). The hope of the developers of high temperature superconductors (HTS) has been to replace liquid helium cooled LTS magnets with HTS magnets that operate at or near liquid nitrogen temperature. There has been limited success in this endeavor, but continued problems with HTS conductors have greatly slowed progress toward this goal. The development of cryocoolers that reliably operate below 4 K will allow magnets made from LTS conductor to remain very competitive for many years to come. A key enabling technology for the use of low temperature cryocoolers on LTS magnets has been the development of HTS leads. This report describes the characteristics of LTS magnets that can be successfully melded to low-temperature cryocoolers. This report will also show when it is not appropriate to consider the use of low-temperature cryocoolers to cool magnets made with LTS conductor. A couple of specific examples of LTS magnets where cryocoolers can be used are given

  9. Reactivity of Heteropolytungstate and Heteropolymolybdate Metal Transition Salts in the Synthesis of Dimethyl Carbonate from Methanol and CO2

    Directory of Open Access Journals (Sweden)

    Amro Al-Amro

    2010-07-01

    Full Text Available A series of Keggin-type heteropoly compounds (HPC having different countercations (Co, Fe and different addenda atoms (W, Mo were synthesized and characterized by means of Fourier-Transform Infrared Spectrometer (FT-IR and X-ray powder diffraction (XRD. The catalytic properties of the prepared catalysts for the dimethyl carbonate (DMC synthesis from CO2 and CH3OH were investigated. The experimental results showed that the catalytic activity is significantly influenced by the type of the countercation and addenda atoms transition metal. Among the catalysts examined, Co1.5PW12O40 is the most active for the DMC synthesis, owing to the synergetic effect between Co and W. Investigating the effect of the support showed that the least acidic one (Al2O3 enhanced the conversion but decreased the DMC selectivity in favor of that of methyl formate (MF, while that of dimethoxy methane remained stable.

  10. ZnO 1-D nanostructures: Low temperature synthesis and ...

    Indian Academy of Sciences (India)

    Wintec

    high-resolution transmission electron microscope (HRTEM;. JEOL 2010). ... low magnification image of the ZnO nanorod arrays show- ing uniformity of the .... in inverted nail like shape. .... where E (local) is the local electric field at the emitting.

  11. Chemical synthesis of hexagonal indium nitride nanocrystallines at low temperature

    Science.gov (United States)

    Wang, Liangbiao; Shen, Qianli; Zhao, Dejian; Lu, Juanjuan; Liu, Weiqiao; Zhang, Junhao; Bao, Keyan; Zhou, Quanfa

    2017-08-01

    In this study, hexagonal indium nitride nanocystallines with high crystallinity have been prepared by the reaction of InCl3·4H2O, sulfur and NaNH2 in an autoclave at 160 °C. The crystal structures and morphologies of the obtained InN sample are characterized by X-ray diffraction and scanning electron microscope. As InCl3·4H2O is substituted by In(NO3)3·4.5H2O, InN nanocrystallines could also be obtained by using the similar method. The photoluminescence spectrum shows that the InN emits a broad peak positioned at 2.3 eV.

  12. Synthesis, structure and low temperature study of electric transport ...

    Indian Academy of Sciences (India)

    1. Introduction. Layered perovskite oxides are a promising group of mixed- conducting materials with potential applications for oxygen- separation membranes, gas sensor devices and electrodes of intermediate-temperature solid oxide fuel cells (Moseley and. Williams 1989; Meixner and Lampe 1996; Skinner and Kil-.

  13. Low temperature synthesis of nanocrystalline scandia-stabilized ...

    Indian Academy of Sciences (India)

    2Chemistry Division, State Forensic Science Laboratory, Kolkata 700037, India. MS received 6 March 2015; accepted 8 July 2015. Abstract. Zirconia stabilized with 11 mol% scandia (11ScSZ) has been successfully synthesized by novel alanine- assisted soft chemical aqueous combustion method. The reaction kinetics ...

  14. Low temperature synthesis of Zn nanowires by physical vapor deposition

    Energy Technology Data Exchange (ETDEWEB)

    Schroeder, Philipp; Kast, Michael; Brueckl, Hubert [Austrian Research Centers GmbH ARC, Nano- Systemtechnologies, Donau-City-Strasse 1, A-1220 Wien (Austria)

    2007-07-01

    We demonstrate catalytic growth of zinc nanowires by physical vapor deposition at modest temperatures of 125-175 C on various substrates. In contrast to conventional approaches using tube furnaces our home-built growth system allows to control the vapor sources and the substrate temperature separately. The silicon substrates were sputter coated with a thin gold layer as metal catalyst. The samples were heated to the growth temperature and subsequently exposed to the zinc vapor at high vacuum conditions. The work pressure was adjusted by the partial pressure of oxygen or argon flow gas. Scanning electron microscopy and atomic force microscopy characterizations revealed that the nanowires exhibit straight, uniform morphology and have diameters in the range of 50-350 nm and lengths up to 70 {mu}m. The Zn nanowires grow independently of the substrates crystal orientation via a catalytic vapor-solid growth mechanism. Since no nanowire formation was observed without gold coating, we expect that the onedimensional growth is initiated by a surface reactive Au seed. ZnO nanowires can be produced in the same preparation chamber by oxidation at 500 C in 1atm (80% Ar, 20% O{sub 2}) for 1 hour. ZnO is highly attractive for sensor applications.

  15. Low temperature synthesis and characterization of carbonated hydroxyapatite nanocrystals

    Science.gov (United States)

    Anwar, Aneela; Asghar, Muhammad Nadeem; Kanwal, Qudsia; Kazmi, Mohsin; Sadiqa, Ayesha

    2016-08-01

    Carbonate substituted hydroxyapatite (CHA) nanorods were synthesized via coprecipitation method from aqueous solution of calcium nitrate tetrahydrate and diammonium hydrogen phosphate (with urea as carbonate ion source) in the presence of ammonium hydroxide solution at 70 °C at the conditions of pH 11. The obtained powders were physically characterized using transmission electron microscopy (TEM), X-ray powder diffraction analysis (XRD), and FTIR and Raman spectroscopy. The particle size was evaluated by Dynamic light scattering (DLS). The chemical structural analysis of as prepared sample was performed using X-ray photoelectron spectroscopy (XPS). After ageing for 12 h, and heat treatment at 1000 °C for 1 h, the product was obtained as highly crystalline nanorods of CHA.

  16. Sorption phenomena of methanol on heat treated coal; Netsushori wo hodokoshita sekitan no methanol kyuchaku tokusei

    Energy Technology Data Exchange (ETDEWEB)

    Yasuda, H.; Kaiho, M.; Yamada, O.; Soneda, Y.; Kobayashi, M.; Makino, M. [National Institute for Resources and Environment, Tsukuba (Japan)

    1996-10-28

    Experiments were carried out to learn methanol sorption characteristics of heat-treated coal. When Taiheiyo coal is heat-treated at 125{degree}C, performed with a first methanol adsorption at 25{degree}C, and then desorption at 25{degree}C, a site with strong interaction with methanol and a site with relatively weak interaction are generated in test samples. A small amount of methanol remains in both sites. Then, when the methanol is desorbed at as low temperature as 70{degree}C, the methanol in the site with strong interaction remains as it has existed therein, but the methanol in the site with relatively weak interaction desorbs partially, hence the adsorption amount in a second adsorption at 25{degree}C increases. However, when desorption is performed at as high temperature as 125{degree}C, the methanol in the site with strong interaction also desorbs, resulting in increased adsorption heat in the second adsorption. The adsorption velocity drops, however. Existence of methanol in a site with strong interaction affects the adsorption velocity, but no effect is given by methanol in a site with weak interaction. 3 refs., 4 figs.

  17. Acclimation of Saccharomyces cerevisiae to low temperature: a chemostat-based transcriptome analysis.

    Science.gov (United States)

    Tai, Siew Leng; Daran-Lapujade, Pascale; Walsh, Michael C; Pronk, Jack T; Daran, Jean-Marc

    2007-12-01

    Effects of suboptimal temperatures on transcriptional regulation in yeast have been extensively studied in batch cultures. To eliminate indirect effects of specific growth rates that are inherent to batch-cultivation studies, genome-wide transcriptional responses to low temperatures were analyzed in steady-state chemostats, grown at a fixed specific growth rate (0.03 h(-1)). Although in vivo metabolic fluxes were essentially the same in cultures grown at 12 and at 30 degrees C, concentrations of the growth-limiting nutrients (glucose or ammonia) were higher at 12 degrees C. This difference was reflected by transcript levels of genes that encode transporters for the growth-limiting nutrients. Several transcriptional responses to low temperature occurred under both nutrient-limitation regimes. Increased transcription of ribosome-biogenesis genes emphasized the importance of adapting protein-synthesis capacity to low temperature. In contrast to observations in cold-shock and batch-culture studies, transcript levels of environmental stress response genes were reduced at 12 degrees C. Transcription of trehalose-biosynthesis genes and intracellular trehalose levels indicated that, in contrast to its role in cold-shock adaptation, trehalose is not involved in steady-state low-temperature adaptation. Comparison of the chemostat-based transcriptome data with literature data revealed large differences between transcriptional reprogramming during long-term low-temperature acclimation and the transcriptional responses to a rapid transition to low temperature.

  18. Sodium dodecyl sulfate-assisted hydrothermal synthesis of mesoporous nickel cobaltite nanoparticles with enhanced catalytic activity for methanol electrooxidation

    Science.gov (United States)

    Ding, Rui; Qi, Li; Jia, Mingjun; Wang, Hongyu

    2014-04-01

    Mesoporous nickel cobaltite (NiCo2O4) nanoparticles have been synthesized via a facile hydrothermal strategy with the assistance of sodium dodecyl sulfate (SDS) soft template (ST). Their physicochemical properties have been characterized via X-ray diffraction (XRD), scanning electron microscopy (SEM) and energy-dispersive X-ray spectra (EDS), transmission electron microscopy (TEM), X-ray photoelectron spectra (XPS) and nitrogen sorption measurements. Their electrocatalytic performances have been examined by cyclic voltammetry (CV), linear sweep voltammetry (LSV), chronoamperometry (CA) and electrochemical impedance spectroscopy (EIS) tests. The obtained NiCo2O4 materials exhibit a typical nanoscale crystalline hexagonal morphology with specific surface area (SSA) and mesopore volume of 88.63 m2 g-1 and 0.298 cm3 g-1. Impressively, the SDS-assisted NiCo2O4 electrode shows a catalytic current density of 125 mA cm-2 and 72% retention for consecutive 1000 s at 0.6 V in 1 M KOH and 0.5 M CH3OH electrolytes towards methanol (CH3OH) electrooxidation, which is better than the one without SDS assistance. The pronounced electrocatalytic activity is largely ascribed to their higher surface intensities of Co and Ni species and superior mesoporous nanostructures, which provide the richer electroactive sites and faster electrochemical kinetics, leading to the enhanced electrocatalytic activity.

  19. Facile Synthesis of Bimetallic Pt-Ag/Graphene Composite and Its Electro-Photo-Synergistic Catalytic Properties for Methanol Oxidation

    Directory of Open Access Journals (Sweden)

    Shuhong Xu

    2016-09-01

    Full Text Available A Pt-Ag/graphene composite (Pt-Ag/GNs was synthesized by the facile aqueous solution method, in which Ag+ was first transformed into Ag2O under UV light irradiation, and then Ag2O, Pt2+, and graphene oxide (GO were simultaneously reduced by formic acid. It was found that Pt-Ag bimetallic nanoparticles were highly dispersed on the surface of graphene, and their size distribution was narrow with an average diameter of 3.3 nm. Electrocatalytic properties of the Pt-Ag/GNs composite were investigated by cyclic voltammograms (CVs, chronoamperometry (CA, CO-stripping voltammograms, and electrochemical impedance spectrum (EIS techniques. It was shown that the Pt-Ag/GNs composite has much higher catalytic activity and stability for the methanol oxidation reaction (MOR and better tolerance toward CO poisoning when compared with Pt/GNs and the commercially available Johnson Matthey 20% Pt/C catalyst (Pt/C-JM. Furthermore, the Pt-Ag/GNs composite showed efficient electro-photo-synergistic catalysis for MOR under UV or visible light irradiation. Particularly in the presence of UV irradiation, the Pt-Ag/GNs composite exhibited an ultrahigh mass activity of 1842.4 mA·mg−1, nearly 2.0 times higher than that without light irradiation (838.3 mA·mg−1.

  20. Active carbons from low temperature conversion chars

    International Nuclear Information System (INIS)

    Adebowale, K.O.; Bayer, E.

    2002-05-01

    Hulls obtained from the fruits of five tropical biomass have been subjected to low temperature conversion process and their chars activated by partial physical gasification to produce active carbons. The biomass are T. catappa, B. nitida, L leucophylla, D. regia and O. martiana. The bulk densities of the samples ranged from 0.32 g.cm 3 to 0.52 g.cm 3 . Out of the samples T. catappa recorded the highest cellulose content (41.9 g.100g -1 ), while O. martiana contained the highest lignin content (40.7 g.100g -1 ). The ash of the samples were low (0.5 - 4.4%). The percentage of char obtained after conversion were high (33.7% - 38.6%). Active carbons obtained from T. catappa, D. regia and O. martiana, recorded high methylene blue numbers and iodine values. They also displayed good micro- and mesostructural characteristics. Micropore volume (V micro ) was between 0.33cm 3 .g -1 - 0.40cm 3 .g -1 , while the mesopore volume(V meso ) was between 0.05 cm 3 .g -1 - 0.07 cm 3 .g -1 . The BET specific surface exceeds 1000 m 2 .g -1 . All these values compared favourably with high grade commercial active carbons. (author)

  1. Low Temperature Catalyst for NH3 Removal

    Science.gov (United States)

    Monje, Oscar; Melendez, Orlando

    2013-01-01

    Air revitalization technologies maintain a safe atmosphere inside spacecraft by the removal of C02, ammonia (NH3), and trace contaminants. NH3 onboard the International Space Station (ISS) is produced by crew metabolism, payloads, or during an accidental release of thermal control refrigerant. Currently, the ISS relies on removing NH3 via humidity condensate and the crew wears hooded respirators during emergencies. A different approach to cabin NH3 removal is to use selective catalytic oxidation (SCO), which builds on thermal catalytic oxidation concepts that could be incorporated into the existing TCCS process equipment architecture on ISS. A low temperature platinum-based catalyst (LTP-Catalyst) developed at KSC was used for converting NH3 to H20 and N2 gas by SCO. The challenge of implementing SCO is to reduce formation of undesirable byproducts like NOx (N20 and NO). Gas mixture analysis was conducted using FTIR spectrometry in the Regenerable VOC Control System (RVCS) Testbed. The RVCS was modified by adding a 66 L semi-sealed chamber, and a custom NH3 generator. The effect of temperature on NH3 removal using the LTP-Catalyst was examined. A suitable temperature was found where NH3 removal did not produce toxic NO, (NO, N02) and N20 formation was reduced.

  2. Pyrocatechol from low-temperature tar

    Energy Technology Data Exchange (ETDEWEB)

    Lowenstein-Lom, W

    1950-01-01

    A method for production and purification of pyrocatechol (I) from low-temperature carbonization effluents was described. Phenosolvan, a mixture of isobutyl, butyl, and amyl acetates, was used for extraction of I from the effluent. After removing most of the solvent by distillation, the separation was completed by batch vacuum distillation at 25 to 50 millimeter Hg. The 4th fraction, containing I 49.2, I homologues 31.1, o-cresol 6.8, xylenols 7.3, and higher boiling material and residue 5.6 percent, was treated in a purification pilot plant, which was described. This fraction was dissolved in an equal weight of C/sub 6/H/sub 6/, then cooled. I was crystallized out in a vacuum crystallizer, centrifuged, and washed with C/sub 6/H/sub 6/, dried in a rotating-plate drier and taken to storage. The purified I melted 100/sup 0/ to 102/sup 0/ and contained 4 to 8 percent homologues or other impurities. A further recrystallization raised its purity to 99.2 percent. Plant capacities and production costs are given.

  3. Enhanced Design Alternative I: Low Temperature Design

    International Nuclear Information System (INIS)

    MacNeil, K.

    1999-01-01

    The purpose of this document is to evaluate Enhanced Design Alternative (EDA) 1, the low temperature repository design concept (CRWMS M and O 1999a). This technical document will provide supporting information for Site Recommendation (SR) and License Application (LA). Preparation of this evaluation will be in accordance with the technical document preparation plan (TDPP), (CRWMS M and O 1999b). EDA 1, one of five EDAs, was evolved from evaluation of a series of design features and alternatives developed during the first phase of the License Application Design Selection (LADS) process. Low, medium, and high temperature concepts were developed from the design features and alternatives prepared during Phase 1 of the LADS effort (CRWMS M and O 1999a). EDA 1 will first be evaluated against a single Screening Criterion, outlined in CRWMS M and O 1999a, which addresses post-closure performance of the repository. The performance of the repository is defined quantitatively as the peak radiological dose rate to an average individual of a critical group at a distance of 20 km from the repository site within 10,000 years. To satisfy this criterion the peak dose rate must not exceed the anticipated regulatory level of 25 mrem/yr within 10,000 years. If the EDA meets the screening criterion, the EDA will be further evaluated against the LADS Phase 2 Evaluation Criteria contained in CRWMS M and O 1999a

  4. Low temperature nitrogen chemistry. Final report

    Energy Technology Data Exchange (ETDEWEB)

    Glarborg, P.; Dam-Johansen, K.; Kristensen, P.G.; Alzueta, M.; Roejel, H.

    1997-04-01

    The results of a two tasks program on Natural Gas Reburning are reported. The work involved an experimental and theoretical study of the reburning and hybrid reburning/SNCR chemistry in the 1000-1500 K range. The interactions between hydrocarbon and nitrogen chemistry under fuel-rich conditions were investigated in order to assess the NO{sub x} reduction potential of low temperature reburning. The effect of reburn fuel(carbon monoxide, methane, acetylene, ethylene, ethane, and methane/ethane mixture), temperature, stoichiometry, reactant dilution, reaction time, and inlet NO level were studied. The results indicate a significant NO reduction potential even below 1400 K, but extrapolation to practical conditions are complicated by inadequate knowledge of the detailed chemistry as well as of the effect of mixing. The possibilities of enhancing the conversion to N{sub 2} instead of NO by adding selective reducing agents (hybrid reburning/SNCR) were evaluated. Our results indicate little synergistic effect between reburn and SNCR. The most simple configuration, where the selective reducing agent is injected together with the burnout air, is not expected to be effective, unless the N-agent is injected in form of an aqueous solution. A chemical kinetic model for reburning and reburn/SNCR is listed and can be obtained by e-mail from pgl(commerical at)kt.dtu.dk.(au) 145 refs.

  5. Active carbons from low temperature conversion chars

    Energy Technology Data Exchange (ETDEWEB)

    Adebowale, K O [Department of Chemistry, University of lbadan, lbadan (Nigeria); Abdus Salam International Centre for Theoretical Physics, Trieste (Italy); Bayer, E [Universitaet Tuebingen, Institut fuer Organische Chemie, Forschungstelle Nukleinsaeure- und Peptidchemie, Tuebingen (Germany)

    2002-05-01

    Hulls obtained from the fruits of five tropical biomass have been subjected to low temperature conversion process and their chars activated by partial physical gasification to produce active carbons. The biomass are T. catappa, B. nitida, L leucophylla, D. regia and O. martiana. The bulk densities of the samples ranged from 0.32 g.cm{sup 3} to 0.52 g.cm{sup 3}. Out of the samples T. catappa recorded the highest cellulose content (41.9 g.100g{sup -1}), while O. martiana contained the highest lignin content (40.7 g.100g{sup -1}). The ash of the samples were low (0.5 - 4.4%). The percentage of char obtained after conversion were high (33.7% - 38.6%). Active carbons obtained from T. catappa, D. regia and O. martiana, recorded high methylene blue numbers and iodine values. They also displayed good micro- and mesostructural characteristics. Micropore volume (V{sub micro}) was between 0.33cm{sup 3}.g{sup -1} - 0.40cm{sup 3}.g{sup -1}, while the mesopore volume(V{sub meso}) was between 0.05 cm{sup 3}.g{sup -1} - 0.07 cm{sup 3}.g{sup -1}. The BET specific surface exceeds 1000 m{sup 2}.g{sup -1}. All these values compared favourably with high grade commercial active carbons. (author)

  6. Low temperature humidification dehumidification desalination process

    International Nuclear Information System (INIS)

    Al-Enezi, Ghazi; Ettouney, Hisham; Fawzy, Nagla

    2006-01-01

    The humidification dehumidification desalination process is viewed as a promising technique for small capacity production plants. The process has several attractive features, which include operation at low temperature, ability to utilize sustainable energy sources, i.e. solar and geothermal, and requirements of low technology level. This paper evaluates the characteristics of the humidification dehumidification desalination process as a function of operating conditions. A small capacity experimental system is used to evaluate the process characteristics as a function of the flow rate of the water and air streams, the temperature of the water stream and the temperature of the cooling water stream. The experimental system includes a packed humidification column, a double pipe glass condenser, a constant temperature water circulation tank and a chiller for cooling water. The water production is found to depend strongly on the hot water temperature. Also, the water production is found to increase upon the increase of the air flow rate and the decrease of the cooling water temperature. The measured air and water temperatures, air relative humidity and the flow rates are used to calculate the air side mass transfer coefficient and the overall heat transfer coefficient. Measured data are found to be consistent with previous literature results

  7. Synthesis and characterization of bimetallic Pd-Ni catalysts in a CeO_2 matrix for the generation of H_2 by the reforming reaction of methanol

    International Nuclear Information System (INIS)

    Contreras C, R.

    2016-01-01

    The hydrothermal method was used for the synthesis of CeO_2 nano rods using Ce(NO_3)_3·6H_2O and NH_4OH. The catalytic support was calcined at 700 degrees Celsius. The synthesis of CeO_2 nano rods were impregnated with an aqueous solution of Ni(NO_3)_2·6H_2O by an incipient wetness impregnation method at an appropriate concentration to yield 5 and 15% of Ni in the catalysts. Then 0.5% of Pd was impregnated using PdCl_2. The samples obtained were calcined at 400 and reduced at 450 degrees Celsius. The catalytic materials were characterized by: temperature programmed reduction (TPR), Scanning Electron Microscopy (Sem) , surface area and X-ray diffraction (XRD) . Sem results showed that the CeO_2 is formed by nano rods and in lesser proportion semi spherical particles. Bet surface area of the catalysts decreases with Ni loading onto the CeO_2 nano rods. Pd O and Ni O were reduced at low and high temperature as was observed by TPR. The CeO_2 one-dimensional nano rods showed a highly crystalline structure with sharp diffraction peaks, with a typical fluorite structure (cubic structure of the CeO_2) and characteristic peaks corresponding to metallic Ni. No diffraction peaks of Pd were found. This is due to the low concentration of this metal in the catalyst. These catalysts showed high activity and selectivity to H_2 at maximum reaction temperature. According to the results of activity and selectivity, the catalysts with Pd-Ni are an alternative for the H_2 production in auto thermal reforming reaction of methanol. (Author)

  8. 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)

    Peng, Xinglan; Zhao, Yanchun; Chen, Duhong; Fan, Yanfang; Wang, Xiao; Wang, Weili; Tian, Jianniao

    2014-01-01

    The outstanding performance PtCu y (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 PtCu y /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 PtCu y /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 PtCu y /rGO catalysts are concerned, the PtCu 2 /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

  9. One Pot Synthesis of Pt/Graphene Composite Using Polyamidoamine/Chitosan as a Template and Its Electrocatalysis for Methanol Oxidation

    Directory of Open Access Journals (Sweden)

    Yanli Wang

    2016-10-01

    Full Text Available A one-pot hydrothermal strategy was used to synthesize Pt/GNs (PAMAM & Pt/GNs (CS composites. Pt nanoparticles are deposited onto graphene sheets (GNs via synchronous reduction of K2PtCl4 and graphene oxide (GO under hydrothermal conditons without additional reducing agent. During the synthesis process, polyamidoamine (PAMAM or chitosan (CS was used as a template respectively to obtain shape controlled Pt particles on the surface of GNs, leading to the formation of flower-like Pt nanoclusters for Pt/GNs (PAMAM and uniform spherical Pt nanoparticles for Pt/GNs (CS. PAMAM and CS are simultaneously served as intrinsic reducing agents to accelerate reduction process; ensuring excellent electrical conductivity of the composites. Electrochemical tests show that Pt/GNs (PAMAM and Pt/GNs (CS have much higher electrocatalytic activity and better stability toward methanol oxidation reaction (MOR in comparison with counterpart Pt/GNs and the commercially available 20% Pt/C catalyst (Pt/C due to their better dispersion of Pt particles, stronger interaction between Pt and substrate materials, and better electron transfer capability.

  10. Materials and Components for Low Temperature Solid Oxide Fuel Cells – an Overview

    Directory of Open Access Journals (Sweden)

    D. Radhika

    2013-06-01

    Full Text Available This article summarizes the recent advancements made in the area of materials and components for low temperature solid oxide fuel cells (LT-SOFCs. LT-SOFC is a new trend in SOFCtechnology since high temperature SOFC puts very high demands on the materials and too expensive to match marketability. The current status of the electrolyte and electrode materials used in SOFCs, their specific features and the need for utilizing them for LT-SOFC are presented precisely in this review article. The section on electrolytes gives an overview of zirconia, lanthanum gallate and ceria based materials. Also, this review article explains the application of different anode, cathode and interconnect materials used for SOFC systems. SOFC can result in better performance with the application of liquid fuels such methanol and ethanol. As a whole, this review article discusses the novel materials suitable for operation of SOFC systems especially for low temperature operation.

  11. One-step synthesis of zero-dimensional hollow nanoporous gold nanoparticles with enhanced methanol electrooxidation performance.

    Science.gov (United States)

    Pedireddy, Srikanth; Lee, Hiang Kwee; Tjiu, Weng Weei; Phang, In Yee; Tan, Hui Ru; Chua, Shu Quan; Troadec, Cedric; Ling, Xing Yi

    2014-09-17

    Nanoporous gold with networks of interconnected ligaments and highly porous structure holds stimulating technological implications in fuel cell catalysis. Current syntheses of nanoporous gold mainly revolve around de-alloying approaches that are generally limited by stringent and harsh multistep protocols. Here we develop a one-step solution phase synthesis of zero-dimensional hollow nanoporous gold nanoparticles with tunable particle size (150-1,000 nm) and ligament thickness (21-54 nm). With faster mass diffusivity, excellent specific electroactive surface area and large density of highly active surface sites, our zero-dimensional nanoporous gold nanoparticles exhibit ~1.4 times enhanced catalytic activity and improved tolerance towards carbonaceous species, demonstrating their superiority over conventional nanoporous gold sheets. Detailed mechanistic study also reveals the crucial heteroepitaxial growth of gold on the surface of silver chloride templates, implying that our synthetic protocol is generic and may be extended to the synthesis of other nanoporous metals via different templates.

  12. Metabolism of methanol in acetogenic bacteria

    International Nuclear Information System (INIS)

    Ivey, D.K.W.

    1987-01-01

    Acetogens can grown on methanol in the presence of a cosubstrate that is more oxidized than methanol. Three mol of acetate is formed from 4 mol methanol and 2 mol CO 2 . One mol of methanol is oxidized to CO 2 . The levels of the tetrahydrofolate enzymes, carbon monoxide dehydrogenase, and corrinoids indicate the presence of the acetyl CoA pathway when growing on methanol. The acetyl-CoA pathway of acetate synthesis as presently understood does not include methanol as a substrate. It is demonstrated that methanol is oxidized to formaldehyde and then to formate by a methanol dehydrogenase. It is also possible that the methyl group of methanol is transferred directly to either a corrinoid-type enzyme, or tetrahydrofolate. When cells of C. thermoautotrophicum are grown on 14 CO 2 , acetate becomes labeled in both carbons with a ratio 14 CH 3 / 14 COOH of 0.7. In addition, methanol gets labeled. When cells are grown on 14 CH 3 OH, label appears in both acetate carbons with a ratio of 3.3, and also appears in CO 2 . Thus methanol is preferentially incorporated into the methyl group of acetate, whereas CO 2 is the preferred source of the carboxyl carbon

  13. Some experiments in low-temperature thermometry

    International Nuclear Information System (INIS)

    Fogle, W.E.

    1982-11-01

    A powdered cerous magnesium nitrate (CMN) temperature scale has been developed in the 0.016 to 3.8 K region which represents an interpolation between the 3 He/ 4 He (T 62 /T 58 ) vapor pressure scale and absolute temperatures in the millikelvin region as determined with a 60 Co in hcp Co nuclear orientation thermometer (NOT). Both ac and dc susceptibility thermometers were used in these experiments. The ac susceptibility of a 13 mg CMN-oil slurry was measured with a mutual inductance bridge employing a SQUID null detector while the dc susceptibility of a 3 mg slurry was measured with a SQUID/flux transformer combination. To check the internal consistency of the NOT, γ-ray intensities were measured both parallel and perpendicular to the Co crystal c-axis. The independent temperatures determined in this fashion were found to agree to within experimental error. For the CMN thermometers employed in these experiments, the susceptibility was found to obey a Curie-Weiss law with a Weiss constant of Δ = 1.05 +- 0.1 mK. The powdered CMN scale in the 0.05 to 1.0 K region was transferred to two germanium resistance thermometers for use in low-temperature specific heat measurements. The integrity of the scale was checked by examining the temperature dependence of the specific heat of high purity copper in the 0.1 to 1 K region. In more recent experiments in this laboratory, the scale was also checked by a comparison with the National Bureau of Standards cryogenic temperature scale (NBS-CTS-1). The agreement between the two scales in the 99 to 206 mK region was found to be on the order of the stated accuracy of the NBS scale

  14. Extraction of tar acids with methanol from low-temperature tar

    Energy Technology Data Exchange (ETDEWEB)

    Funasaka, W; Yokogawa, C; Suga, S

    1948-01-01

    From 20 grams crude middle oil, boiling at 200/sup 0/ to 250/sup 0/, acid content 40%, tar acids were extracted at 20/sup 0/ to 30/sup 0/ with MeOH for comparison with EtOH, NMe/sub 3/, and ethylene glycol. When 80% MeOH is used, the oil extracted amounts to 61%, including 9% acids, if the ratio of crude oil and solvent is kept at 1:2. EtOH is inferior to MeOH. The properties of the crude oil and the purified oil extracted with 80% MeOH are described.

  15. Composite Materials for Low-Temperature Applications

    Science.gov (United States)

    2008-01-01

    Composite materials with improved thermal conductivity and good mechanical strength properties should allow for the design and construction of more thermally efficient components (such as pipes and valves) for use in fluid-processing systems. These materials should have wide application in any number of systems, including ground support equipment (GSE), lunar systems, and flight hardware that need reduced heat transfer. Researchers from the Polymer Science and Technology Laboratory and the Cryogenics Laboratory at Kennedy Space Center were able to develop a new series of composite materials that can meet NASA's needs for lightweight materials/composites for use in fluid systems and also expand the plastic-additive markets. With respect to thermal conductivity and physical properties, these materials are excellent alternatives to prior composite materials and can be used in the aerospace, automotive, military, electronics, food-packaging, and textile markets. One specific application of the polymeric composition is for use in tanks, pipes, valves, structural supports, and components for hot or cold fluid-processing systems where heat flow through materials is a problem to be avoided. These materials can also substitute for metals in cryogenic and other low-temperature applications. These organic/inorganic polymeric composite materials were invented with significant reduction in heat transfer properties. Decreases of 20 to 50 percent in thermal conductivity versus that of the unmodified polymer matrix were measured. These novel composite materials also maintain mechanical properties of the unmodified polymer matrix. These composite materials consist of an inorganic additive combined with a thermoplastic polymer material. The intrinsic, low thermal conductivity of the additive is imparted into the thermoplastic, resulting in a significant reduction in heat transfer over that of the base polymer itself, yet maintaining most of the polymer's original properties. Normal

  16. Performance comparison of low-temperature direct alcohol fuel cells with different anode catalysts

    Science.gov (United States)

    Zhou, W. J.; Zhou, B.; Li, W. Z.; Zhou, Z. H.; Song, S. Q.; Sun, G. Q.; Xin, Q.; Douvartzides, S.; Goula, M.; Tsiakaras, P.

    Low-temperature polymer electrolyte membrane fuel cells directly fed by methanol and ethanol were investigated employing carbon supported Pt, PtSn and PtRu as anode catalysts, respectively. Employing Pt/C as anode catalyst, both direct methanol fuel cell (DMFC) and direct ethanol fuel cell (DEFC) showed poor performances even in presence of high Pt loading on anode. It was found that the addition of Ru or Sn to the Pt dramatically enhances the electro-oxidation of both methanol and ethanol. It was also found that the single cell adopting PtRu/C as anode shows better DMFC performance, while PtSn/C catalyst shows better DEFC performance. The single fuel cell using PtSn/C as anode catalyst at 90 °C shows similar power densities whenever fueled by methanol or ethanol. The cyclic voltammetry (CV) and single fuel cell tests indicated that PtRu is more suitable for DMFC while PtSn is more suitable for DEFC.

  17. Low Temperature Surface Carburization of Stainless Steels

    Energy Technology Data Exchange (ETDEWEB)

    Collins, Sunniva R; Heuer, Arthur H; Sikka, Vinod K

    2007-12-07

    Low-temperature colossal supersaturation (LTCSS) is a novel surface hardening method for carburization of austenitic stainless steels (SS) without the precipitation of carbides. The formation of carbides is kinetically suppressed, enabling extremely high or colossal carbon supersaturation. As a result, surface carbon concentrations in excess of 12 at. % are routinely achieved. This treatment increases the surface hardness by a factor of four to five, improving resistance to wear, corrosion, and fatigue, with significant retained ductility. LTCSS is a diffusional surface hardening process that provides a uniform and conformal hardened gradient surface with no risk of delamination or peeling. The treatment retains the austenitic phase and is completely non-magnetic. In addition, because parts are treated at low temperature, they do not distort or change dimensions. During this treatment, carbon diffusion proceeds into the metal at temperatures that constrain substitutional diffusion or mobility between the metal alloy elements. Though immobilized and unable to assemble to form carbides, chromium and similar alloying elements nonetheless draw enormous amounts of carbon into their interstitial spaces. The carbon in the interstitial spaces of the alloy crystals makes the surface harder than ever achieved before by more conventional heat treating or diffusion process. The carbon solid solution manifests a Vickers hardness often exceeding 1000 HV (equivalent to 70 HRC). This project objective was to extend the LTCSS treatment to other austenitic alloys, and to quantify improvements in fatigue, corrosion, and wear resistance. Highlights from the research include the following: • Extension of the applicability of the LTCSS process to a broad range of austenitic and duplex grades of steels • Demonstration of LTCSS ability for a variety of different component shapes and sizes • Detailed microstructural characterization of LTCSS-treated samples of 316L and other alloys

  18. A Computational Framework for Efficient Low Temperature Plasma Simulations

    Science.gov (United States)

    Verma, Abhishek Kumar; Venkattraman, Ayyaswamy

    2016-10-01

    Over the past years, scientific computing has emerged as an essential tool for the investigation and prediction of low temperature plasmas (LTP) applications which includes electronics, nanomaterial synthesis, metamaterials etc. To further explore the LTP behavior with greater fidelity, we present a computational toolbox developed to perform LTP simulations. This framework will allow us to enhance our understanding of multiscale plasma phenomenon using high performance computing tools mainly based on OpenFOAM FVM distribution. Although aimed at microplasma simulations, the modular framework is able to perform multiscale, multiphysics simulations of physical systems comprises of LTP. Some salient introductory features are capability to perform parallel, 3D simulations of LTP applications on unstructured meshes. Performance of the solver is tested based on numerical results assessing accuracy and efficiency of benchmarks for problems in microdischarge devices. Numerical simulation of microplasma reactor at atmospheric pressure with hemispherical dielectric coated electrodes will be discussed and hence, provide an overview of applicability and future scope of this framework.

  19. Synthesis of ZSM-5 zeolite from coal fly ash and rice husk: characterization and application for partial oxidation of methane to methanol

    Science.gov (United States)

    Krisnandi, Y. K.; Yanti, F. M.; Murti, S. D. S.

    2017-04-01

    Indonesian fly ash (SiO2/Al2O3 mole ratio = 3.59) was used together with rice husk (SiO2 92%) as raw material for mesoporous ZSM-5 zeolite synthesis. Prior being used, coal fly ash and rice husk were subjected to pre-treatment in order to extract silicate (SiO4 4-) and aluminate (AlO4 5-) and to remove the impurities. Then the ZSM-5 zeolite were synthesized through hydrothermal treatment using two types of templates (TPAOH and PDDA). The as-synthesized ZSM-5 was characterized using FTIR, XRD, SEM-EDX, and BET. The result of FTIR showed peaks at 1250-950 cm-1 (v asymetric T-O), 820-650 cm-1 (v symetric T-O), and at 650-500 cm-1 confirming the presence of the five number ring of the pentasil structure. The result of XRD showed the appearance of certain peaks in the position 2 theta between 7-9° and 22-25° indicative of ZSM-5 structure, but also showed the pattern of low intensity magnetite and hematite. The SEM image showed the rough surface of hexagonal crystals from ZSM-5 structure, indicative of mesoporosity in the structure. EDX result showed Si/Al ratio of 20, while surface area analysis gave SA of 43.16. The ZSM-5 zeolites then was modified with cobalt oxide through impregnation method. The catalytic activity as heterogeneous catalysts in partial oxidation of methane was tested. The result showed that hence the catalytic activity of ZSM-5 and Co/ZSM-5 from fly ash and rice husk were still inferior compared to the pro-analysis sourced-counterpart, they were potential to be used as catalyst in the partial oxidation of methane to methanol.

  20. Quantum Simulations of Low Temperature High Energy Density Matter

    National Research Council Canada - National Science Library

    Voth, Gregory

    2004-01-01

    .... Using classical molecular dynamics simulations to evaluate these equilibrium properties would predict qualitatively incorrect results for low temperature solid hydrogen, because of the highly quantum...

  1. Containment test in area of high latitude and low temperature

    International Nuclear Information System (INIS)

    Cai Jiantao; Ni Yongsheng; Jia Wutong

    2014-01-01

    The effects of high latitude and low temperature on containment test are detailed analyzed from the view of design, equipment, construct and start-up, and the solution is put forward. The major problems resolved is as below: the effects of low temperature and high wind on defect inspection of the containment surface, the effects of test load on the affiliated equipment of containment in the condition of low temperature, and the effects of low temperature on the containment leak rate measurement. Application in Hongyanhe Unit 1 showed that the proposed scheme can effectively overcome the influence of adverse weather on the containment test. (authors)

  2. The energies of formation and mobilities of Cu surface species on Cu and ZnO in methanol and water gas shift atmospheres studied by DFT

    DEFF Research Database (Denmark)

    Rasmussen, Dominik Bjørn; Janssens, Ton V.W.; Temel, Burcin

    2012-01-01

    Catalysts based on copper, such as the Cu/ZnO/Al2O3 system are widely used for industrial scale methanol synthesis and the low temperature water gas shift reaction. A common characteristic of these catalysts is that they deactivate quite rapidly during operation and therefore understanding...... their deactivation by sintering is highly relevant. In this work, we study the nature of the species that are responsible for transport of the Cu metal in this catalyst type using density functional theory calculations within a chemical potential formalism. The stability and mobility of Cu–X (Cu, OH, CO, CH3O, HCOO...

  3. Exploring the limits: A low-pressure, low-temperature Haber-Bosch process

    Science.gov (United States)

    Vojvodic, Aleksandra; Medford, Andrew James; Studt, Felix; Abild-Pedersen, Frank; Khan, Tuhin Suvra; Bligaard, T.; Nørskov, J. K.

    2014-04-01

    The Haber-Bosch process for ammonia synthesis has been suggested to be the most important invention of the 20th century, and called the ‘Bellwether reaction in heterogeneous catalysis’. We examine the catalyst requirements for a new low-pressure, low-temperature synthesis process. We show that the absence of such a process for conventional transition metal catalysts can be understood as a consequence of a scaling relation between the activation energy for N2 dissociation and N adsorption energy found at the surface of these materials. A better catalyst cannot obey this scaling relation. We define the ideal scaling relation characterizing the most active catalyst possible, and show that it is theoretically possible to have a low pressure, low-temperature Haber-Bosch process. The challenge is to find new classes of catalyst materials with properties approaching the ideal, and we discuss the possibility that transition metal compounds have such properties.

  4. Synthesis and Electrical Resistivity of Nickel Polymethacrylate

    Science.gov (United States)

    Chohan, M. H.; Khalid, A. H.; Zulfiqar, M.; Butt, P. K.; Khan, Farah; Hussain, Rizwan

    Synthesis of nickel polymethacrylate was carried out using methanolic solutions of sodium hydroxide and polymethacrylic acid. The electrical resistivity of the pellets made from Ni-polymethacrylate was measured at different voltages and temperatures. Results showed that the electrical resistivity of Ni-polymethacrylate decreases significantly with voltage in high temperature regions but the decrease is insignificant at temperatures nearing room temperature. The activation energy at low temperatures is approximately 0.8 eV whereas at high temperature it is in the range 0.21-0.27 eV.

  5. Endogenous Methanol Regulates Mammalian Gene Activity

    Science.gov (United States)

    Komarova, Tatiana V.; Petrunia, Igor V.; Shindyapina, Anastasia V.; Silachev, Denis N.; Sheshukova, Ekaterina V.; Kiryanov, Gleb I.; Dorokhov, Yuri L.

    2014-01-01

    We recently showed that methanol emitted by wounded plants might function as a signaling molecule for plant-to-plant and plant-to-animal communications. In mammals, methanol is considered a poison because the enzyme alcohol dehydrogenase (ADH) converts methanol into toxic formaldehyde. However, the detection of methanol in the blood and exhaled air of healthy volunteers suggests that methanol may be a chemical with specific functions rather than a metabolic waste product. Using a genome-wide analysis of the mouse brain, we demonstrated that an increase in blood methanol concentration led to a change in the accumulation of mRNAs from genes primarily involved in detoxification processes and regulation of the alcohol/aldehyde dehydrogenases gene cluster. To test the role of ADH in the maintenance of low methanol concentration in the plasma, we used the specific ADH inhibitor 4-methylpyrazole (4-MP) and showed that intraperitoneal administration of 4-MP resulted in a significant increase in the plasma methanol, ethanol and formaldehyde concentrations. Removal of the intestine significantly decreased the rate of methanol addition to the plasma and suggested that the gut flora may be involved in the endogenous production of methanol. ADH in the liver was identified as the main enzyme for metabolizing methanol because an increase in the methanol and ethanol contents in the liver homogenate was observed after 4-MP administration into the portal vein. Liver mRNA quantification showed changes in the accumulation of mRNAs from genes involved in cell signalling and detoxification processes. We hypothesized that endogenous methanol acts as a regulator of homeostasis by controlling the mRNA synthesis. PMID:24587296

  6. Endogenous methanol regulates mammalian gene activity.

    Directory of Open Access Journals (Sweden)

    Tatiana V Komarova

    Full Text Available We recently showed that methanol emitted by wounded plants might function as a signaling molecule for plant-to-plant and plant-to-animal communications. In mammals, methanol is considered a poison because the enzyme alcohol dehydrogenase (ADH converts methanol into toxic formaldehyde. However, the detection of methanol in the blood and exhaled air of healthy volunteers suggests that methanol may be a chemical with specific functions rather than a metabolic waste product. Using a genome-wide analysis of the mouse brain, we demonstrated that an increase in blood methanol concentration led to a change in the accumulation of mRNAs from genes primarily involved in detoxification processes and regulation of the alcohol/aldehyde dehydrogenases gene cluster. To test the role of ADH in the maintenance of low methanol concentration in the plasma, we used the specific ADH inhibitor 4-methylpyrazole (4-MP and showed that intraperitoneal administration of 4-MP resulted in a significant increase in the plasma methanol, ethanol and formaldehyde concentrations. Removal of the intestine significantly decreased the rate of methanol addition to the plasma and suggested that the gut flora may be involved in the endogenous production of methanol. ADH in the liver was identified as the main enzyme for metabolizing methanol because an increase in the methanol and ethanol contents in the liver homogenate was observed after 4-MP administration into the portal vein. Liver mRNA quantification showed changes in the accumulation of mRNAs from genes involved in cell signalling and detoxification processes. We hypothesized that endogenous methanol acts as a regulator of homeostasis by controlling the mRNA synthesis.

  7. Low temperature barrier wellbores formed using water flushing

    Science.gov (United States)

    McKinzie, II; John, Billy [Houston, TX; Keltner, Thomas Joseph [Spring, TX

    2009-03-10

    A method of forming an opening for a low temperature well is described. The method includes drilling an opening in a formation. Water is introduced into the opening to displace drilling fluid or indigenous gas in the formation adjacent to a portion of the opening. Water is produced from the opening. A low temperature fluid is applied to the opening.

  8. Effects of low temperature and drought on the physiological and ...

    African Journals Online (AJOL)

    To find out how oil palm adapts to the environmental conditions, the dynamics of a series of important physiological components derived from the leaves of potted oil palm seedlings under drought stress (DS) (water with holding) and low temperature stress (LTS) (10°C) were studied. The results showed that low temperature ...

  9. Low temperature magnetic structure of MnSe

    Indian Academy of Sciences (India)

    Abstract. In this paper we report low temperature neutron diffraction studies on MnSe in order to understand the anomalous behaviour of their magnetic and transport prop- erties. Our study indicates that at low temperatures MnSe has two coexisting crystal structures, high temperature NaCl and hexagonal NiAs. NiAs phase ...

  10. Low temperature gaseous surface hardening of stainless steel

    DEFF Research Database (Denmark)

    Christiansen, Thomas; Somers, Marcel A. J.

    2010-01-01

    The present contribution gives an overview of some of the technological aspects of low temperature thermochemical treatment of stainless steel. Examples of low temperature gaseous nitriding, carburising and nitrocarburising of stainless steel are presented and discussed. In particular......, the morphology, microstructure and characteristics of so-called expanite “layers” on stainless steel are addressed....

  11. Physiological and biochemical responses to low temperature stress ...

    African Journals Online (AJOL)

    Cuttings of three hybrid clones of P. ussuriensis × P. deltoides were exposed to different low temperatures (cold and freezing) for 24 h, or consecutive low temperatures (5°C, 0 to 120 h), to determine physiological and biochemical responses to cold stress in these woody plants. Soluble sugar and protein contents increased ...

  12. Biological and Biomimetic Low-Temperature Routes to Materials for Energy Applications

    Energy Technology Data Exchange (ETDEWEB)

    Morse, Daniel E. [Univ. of California, Santa Barbara, CA (United States). Inst. for Collaborative Biotechnologies

    2016-08-29

    New materials are needed to significantly improve the efficiencies of energy harnessing, transduction and storage, yet the synthesis of advanced composites and multi-metallic semiconductors with nanostructures optimized for these functions remains poorly understood and even less well controlled. To help address this need, we proposed three goals: (1) to further investigate the hierarchical structure of the biologically synthesized silica comprising the skeletal spicules of sponges that we discovered, to better resolve the role and mechanism of templating by the hierarchically assembled silicatein protein filament; (2) to extend our molecular and genetic analyses and engineering of silicatein, the self-assembling, structure-directing, silica-synthesizing enzyme we discovered and characterized, to better understand and manipulate the catalysis and templating of semiconductor synthesis,; and (3) to further investigate, scale up and harness the biologically inspired, low-temperature, kinetically controlled catalytic synthesis method we developed (based on the mechanism we discovered in silicatein) to investigate the kinetic control of the structure-function relationships in magnetic materials, and develop new materials for energy applications. The bio-inspired catalytic synthesis method we have developed is low-cost, low temperature, and operates without the use of polluting chemicals. In addition to direct applications for improvement of batteries and fuel cells, the broader impact of this research includes a deeper fundamental understanding of the factors governing kinetically controlled synthesis and its control of the emergent nanostructure and performance of a wide range of nanomaterials for energy applications.

  13. Cu₂O template synthesis of high-performance PtCu alloy yolk-shell cube catalysts for direct methanol fuel cells.

    Science.gov (United States)

    Ye, Sheng-Hua; He, Xu-Jun; Ding, Liang-Xin; Pan, Zheng-Wei; Tong, Ye-Xiang; Wu, Mingmei; Li, Gao-Ren

    2014-10-21

    Novel PtCu alloy yolk-shell cubes were fabricated via the disproportionation and displacement reactions in Cu2O yolk-shell cubes, and they exhibit significantly improved catalytic activity and durability for methanol electrooxidation.

  14. Low Temperature Regolith Bricks for In-Situ Structural Material

    Science.gov (United States)

    Grossman, Kevin; Sakthivel, Tamil S.; Mantovani, James; Seal, Sudipta

    2016-01-01

    Current technology for producing in-situ structural materials on future missions to Mars or the moon relies heavily on energy-intensive sintering processes to produce solid bricks from regolith. This process requires heating the material up to temperatures in excess of 1000 C and results in solid regolith pieces with compressive strengths in the range of 14000 to 28000 psi, but are heavily dependent on the porosity of the final material and are brittle. This method is currently preferred over a low temperature cementation process to prevent consumption of precious water and other non-renewable materials. A high strength structural material with low energy requirements is still needed for future colonization of other planets. To fulfill these requirements, a nano-functionalization process has been developed to produce structural bricks from regolith simulant and shows promising mechanical strength results. Functionalization of granular silicate particles into alkoxides using a simple low temperature chemical process produces a high surface area zeolite particles that are held together via inter-particle oxygen bonding. Addition of water in the resulting zeolite particles produces a sol-gel reaction called "inorganic polymerization" which gives a strong solid material after a curing process at 60 C. The aqueous solution by-product of the reaction is currently being investigated for its reusability; an essential component of any ISRU technology. For this study, two batches of regolith bricks are synthesized from JSC-1A; the first batch from fresh solvents and chemicals, the second batch made from the water solution by-product of the first batch. This is done to determine the feasibility of recycling necessary components of the synthesis process, mainly water. Characterization including BET surface area, SEM, and EDS has been done on the regolith bricks as well as the constituent particles,. The specific surface area of 17.53 sq m/g (average) of the granular regolith

  15. Low temperature aluminum nitride thin films for sensory applications

    Energy Technology Data Exchange (ETDEWEB)

    Yarar, E.; Zamponi, C.; Piorra, A.; Quandt, E., E-mail: eq@tf.uni-kiel.de [Institute for Materials Science, Chair for Inorganic Functional Materials, Kiel University, D-24143 Kiel (Germany); Hrkac, V.; Kienle, L. [Institute for Materials Science, Chair for Synthesis and Real Structure, Kiel University, D-24143 Kiel (Germany)

    2016-07-15

    A low-temperature sputter deposition process for the synthesis of aluminum nitride (AlN) thin films that is attractive for applications with a limited temperature budget is presented. Influence of the reactive gas concentration, plasma treatment of the nucleation surface and film thickness on the microstructural, piezoelectric and dielectric properties of AlN is investigated. An improved crystal quality with respect to the increased film thickness was observed; where full width at half maximum (FWHM) of the AlN films decreased from 2.88 ± 0.16° down to 1.25 ± 0.07° and the effective longitudinal piezoelectric coefficient (d{sub 33,f}) increased from 2.30 ± 0.32 pm/V up to 5.57 ± 0.34 pm/V for film thicknesses in the range of 30 nm to 2 μm. Dielectric loss angle (tan δ) decreased from 0.626% ± 0.005% to 0.025% ± 0.011% for the same thickness range. The average relative permittivity (ε{sub r}) was calculated as 10.4 ± 0.05. An almost constant transversal piezoelectric coefficient (|e{sub 31,f}|) of 1.39 ± 0.01 C/m{sup 2} was measured for samples in the range of 0.5 μm to 2 μm. Transmission electron microscopy (TEM) investigations performed on thin (100 nm) and thick (1.6 μm) films revealed an (002) oriented AlN nucleation and growth starting directly from the AlN-Pt interface independent of the film thickness and exhibit comparable quality with the state-of-the-art AlN thin films sputtered at much higher substrate temperatures.

  16. Evolution of low-temperature phases in a low-temperature structural transition of a La cuprate

    International Nuclear Information System (INIS)

    Inoue, Y.; Horibe, Y.; Koyama, Y.

    1997-01-01

    The microstructure produced by a low-temperature structural phase transition in La 1.5 Nd 0.4 Sr 0.1 CuO 4 has been examined by transmission electron microscopy with the help of imaging plates. The low-temperature transition was found to be proceeded not only by the growth of the Pccn/low-temperature-tetragonal phases nucleated along the twin boundary but also by the nucleation and growth of the phases in the interior of the low-temperature-orthorhombic domain. In addition, because the map of the octahedron tilt as an order parameter is not identical to that of the spontaneous strain accompanied by the transition, the microstructure below the transition is understood to be a very complex mixture of the low-temperature phases. copyright 1997 The American Physical Society

  17. Production of methanol/DME from biomass

    DEFF Research Database (Denmark)

    Ahrenfeldt, Jesper; Henriksen, Ulrik Birk; Münster-Swendsen, Janus

    In this project the production of DME/methanol from biomass has been investigated. Production of DME/methanol from biomass requires the use of a gasifier to transform the solid fuel to a synthesis gas (syngas) - this syngas can then be catalytically converted to DME/methanol. Two different gasifier...... cleaning. This was proved by experiments. Thermodynamic computer models of DME and methanol plants based on using the Two-Stage Gasification concept were created to show the potential of such plants. The models showed that the potential biomass to DME/methanol + net electricity energy efficiency was 51...... gasification, but little information exists on using these types of gasifiers for biomass gasification. The experiments performed provided quantitative data on product and gas composition as a function of operation conditions. Biomass can be gasified with less oxygen consumption compared to coal. The organic...

  18. Recycling of greenhouse gases via methanol

    Energy Technology Data Exchange (ETDEWEB)

    Bill, A [Paul Scherrer Inst. (PSI), Villigen (Switzerland); Eliasson, B; Kogelschatz, U [ABB Corporate Research Center, Baden-Daettwil (Switzerland)

    1997-06-01

    Greenhouse gas emissions to the atmosphere can be mitigated by using direct control technologies (capture, disposal or chemical recycling). We report on carbon dioxide and methane recycling with other chemicals, especially with hydrogen and oxygen, to methanol. Methanol synthesis from CO{sub 2} is investigated on various catalysts at moderate pressures ({<=}30 bar) and temperatures ({<=}300{sup o}C). The catalysts show good methanol activities and selectivities. The conversion of CO{sub 2} and CH{sub 4} to methanol is also studied in a silent electrical discharge at pressures of 1 to 4 bar and temperatures close to room temperature. Methanol yields are given for mixtures of CO{sub 2}/H{sub 2}, CH{sub 4}/O{sub 2} and also for CH{sub 4} and air mixtures. (author) 2 figs., 5 refs.

  19. Low-temperature phase transformation in rubidium and cesium superoxides

    International Nuclear Information System (INIS)

    Alikhanov, R.A.; Toshich, B.S.; Smirnov, L.S.

    1980-01-01

    Crystal structures of rubidium and cesium superoxides which are two interpenetrating lattices of metal ions and oxygen molecule ions reveal a number of phase transformations with temperature decrease. Crystal-phase transformations in CsO 2 are 1-2, 2-3 and low temperature one 3-4 at 378, 190 and 10 K. Low temperature transition is considered as the instability of lattice quadrupoles of oxygen molecule ions to phase transformation of the order-disorder type. Calculated temperatures of low temperature phase transformations in PbO 2 and CsO 2 agree with experimental calculations satisfactory [ru

  20. Low temperature safety of lithium-thionyl chloride cells

    Science.gov (United States)

    Subbarao, S.; Deligiannis, F.; Shen, D. H.; Dawson, S.; Halpert, G.

    The use of lithium thionyl chloride cells for low-temperature applications is presently restricted because of their unsafe behavior. An attempt is made in the present investigation to identify the safe/unsafe low temperature operating conditions and to understand the low temperature cell chemistry responsible for the unsafe behavior. Cells subjected to extended reversal at low rate and -40 C were found to explode upon warm-up. Lithium was found to deposit on the carbon cathodes during reversal. Warming up to room temperature may be accelerating the lithium corrosion in the electrolyte. This may be one of the reasons for the cell thermal runaway.

  1. One-step synthesis of high-yield biodiesel from waste cooking oils by a novel and highly methanol-tolerant immobilized lipase.

    Science.gov (United States)

    Wang, Xiumei; Qin, Xiaoli; Li, Daoming; Yang, Bo; Wang, Yonghua

    2017-07-01

    This study reported a novel immobilized MAS1 lipase from marine Streptomyces sp. strain W007 for synthesizing high-yield biodiesel from waste cooking oils (WCO) with one-step addition of methanol in a solvent-free system. Immobilized MAS1 lipase was selected for the transesterification reactions with one-step addition of methanol due to its much more higher biodiesel yield (89.50%) when compared with the other three commercial immobilized lipases (biodiesel yield (95.45%) was acquired with one-step addition of methanol under the optimized conditions. Moreover, it was observed that immobilized MAS1 lipase retained approximately 70% of its initial activity after being used for four batch cycles. Finally, the obtained biodiesel was further characterized using FT-IR, 1 H and 13 C NMR spectroscopy. These findings indicated that immobilized MAS1 lipase is a promising catalyst for biodiesel production from WCO with one-step addition of methanol under high methanol concentration. Copyright © 2017 Elsevier Ltd. All rights reserved.

  2. Low-temperature localization in the transport properties of self ...

    Indian Academy of Sciences (India)

    Transport properties; scattering mechanisms; low temperature localization. 1. Introduction ... Mn4+ appears in these compounds due to the La defi- ciency, leading ... microscopy (SEM) image in figure 1 shows the size and mor- phology of the ...

  3. Detection of dark matter particles with low temperature phonon sensors

    International Nuclear Information System (INIS)

    Sadoulet, B.

    1988-03-01

    Taking as an example the development effort in Berkeley, the author discusses for nonspecialists (Astronomers and Particle Physicists) the promises of phonon sensing at low temperature for the detection of dark matter particles and the difficulties faced. 31 refs

  4. Total Dose Effects on Bipolar Integrated Circuits at Low Temperature

    Science.gov (United States)

    Johnston, A. H.; Swimm, R. T.; Thorbourn, D. O.

    2012-01-01

    Total dose damage in bipolar integrated circuits is investigated at low temperature, along with the temperature dependence of the electrical parameters of internal transistors. Bandgap narrowing causes the gain of npn transistors to decrease far more at low temperature compared to pnp transistors, due to the large difference in emitter doping concentration. When irradiations are done at temperatures of -140 deg C, no damage occurs until devices are warmed to temperatures above -50 deg C. After warm-up, subsequent cooling shows that damage is then present at low temperature. This can be explained by the very strong temperature dependence of dispersive transport in the continuous-time-random-walk model for hole transport. For linear integrated circuits, low temperature operation is affected by the strong temperature dependence of npn transistors along with the higher sensitivity of lateral and substrate pnp transistors to radiation damage.

  5. 2014 Low-Temperature and Coproduced Geothermal Resources Fact Sheet

    Energy Technology Data Exchange (ETDEWEB)

    Tim Reinhardt, Program Manager

    2014-09-01

    As a growing sector of geothermal energy development, the Low-Temperature Program supports innovative technologies that enable electricity production and cascaded uses from geothermal resources below 300° Fahrenheit.

  6. Automation of low temperature positron annihilation spectroscopy system

    International Nuclear Information System (INIS)

    Chaturvedi, T.P.; Venkiteswaran, S.; Pujari, P.K.

    1997-01-01

    This paper describes the automation implemented in the low temperature measurements in positron annihilation spectroscopic studies. This has not only widened the scope of the positron research, but also helps achieve result with better precision. (author). 3 refs., 1 fig

  7. Physiological and biochemical responses to low temperature stress ...

    African Journals Online (AJOL)

    ajl yemi

    2011-11-09

    Nov 9, 2011 ... Levels of electrolyte leak and MDA were lower than in UD189 or UD191. Poplar hybrid clones ... humidity, exposure, and water status and health conditions of ... consecutive low temperature treatment; and to detect variation ...

  8. Highly Effective Thermal Regenerator for Low Temperature Cryocoolers, Phase I

    Data.gov (United States)

    National Aeronautics and Space Administration — Future missions to investigate the structure and evolution of the universe require highly efficient, low-temperature cryocoolers for low-noise detector systems. We...

  9. Strong anisotropy in the low temperature Compton profiles of ...

    Indian Academy of Sciences (India)

    able for comparison with theory, the resistivity data in α-Ga at low temperature strongly support this anisotropic ... renormalized free-atom (RFA) model [3], band model [5–7] and quantum Monte Carlo ... probability distribution function.

  10. Low temperature gaseous nitriding of Ni based superalloys

    DEFF Research Database (Denmark)

    Eliasen, K. M.; Christiansen, Thomas Lundin; Somers, Marcel A. J.

    2010-01-01

    In the present work the nitriding response of selected Ni based superalloys at low temperatures is addressed. The alloys investigated are nimonic series nos. 80, 90, 95 and 100 and nichrome (Ni/Cr......In the present work the nitriding response of selected Ni based superalloys at low temperatures is addressed. The alloys investigated are nimonic series nos. 80, 90, 95 and 100 and nichrome (Ni/Cr...

  11. Evaluation Method for Low-Temperature Performance of Lithium Battery

    Science.gov (United States)

    Wang, H. W.; Ma, Q.; Fu, Y. L.; Tao, Z. Q.; Xiao, H. Q.; Bai, H.; Bai, H.

    2018-05-01

    In this paper, the evaluation method for low temperature performance of lithium battery is established. The low temperature performance level was set up to determine the best operating temperature range of the lithium battery using different cathode materials. Results are shared with the consumers for the proper use of lithium battery to make it have a longer service life and avoid the occurrence of early rejection.

  12. Measured Performance of a Low Temperature Air Source Heat Pump

    Energy Technology Data Exchange (ETDEWEB)

    R.K. Johnson

    2013-09-01

    A 4-ton Low Temperature Heat Pump (LTHP) manufactured by Hallowell International was installed in a residence near New Haven, Connecticut and monitored over two winters of operation. After attending to some significant service issues, the heat pump operated as designed. This report should be considered a review of the dual compressor “boosted heat pump” technology. The Low Temperature Heat Pump system operates with four increasing levels of capacity (heat output) as the outdoor temperature drops.

  13. Microstructural Characterization of Low Temperature Gas Nitrided Martensitic Stainless Steel

    DEFF Research Database (Denmark)

    Fernandes, Frederico Augusto Pires; Christiansen, Thomas Lundin; Somers, Marcel A. J.

    2015-01-01

    The present work presents microstructural investigations of the surface zone of low temperature gas nitrided precipitation hardening martensitic stainless steel AISI 630. Grazing incidence X-ray diffraction was applied to investigate the present phases after successive removal of very thin sections...... of the sample surface. The development of epsilon nitride, expanded austenite and expanded martensite resulted from the low temperature nitriding treatments. The microstructural features, hardness and phase composition are discussed with emphasis on the influence of nitriding duration and nitriding potential....

  14. INFLUENCE OF A LOW TEMPERATURE AGEING ON THE ...

    African Journals Online (AJOL)

    The effect of a low temperature ageing treatment on the hardness, tensile and corrosion characteristics of sand cast Al-6.5%Si-0.35%Mg alloy was studied. The temper conditions are low temperature ageing at 90oC, 95oC, 100oCand 105oC respectively followed by ageing to 180oC for 2 hrs. This was compared with the ...

  15. Correlation functions of one-dimensional bosons at low temperature

    Energy Technology Data Exchange (ETDEWEB)

    Kozlowski, K.K. [Deutsches Elektronen-Synchrotron (DESY), Hamburg (Germany); Maillet, J.M. [CNRS, ENS Lyon (France). Lab. de Physique; Slavnov, N.A. [Steklov Mathematical Institute, Moscow (Russian Federation)

    2010-12-15

    We consider the low-temperature limit of the long-distance asymptotic behavior of the finite temperature density-density correlation function in the one-dimensional Bose gas derived recently in the algebraic Bethe Ansatz framework. Our results confirm the predictions based on the Luttinger liquid and conformal field theory approaches. We also demonstrate that the amplitudes arising in this asymptotic expansion at low-temperature coincide with the amplitudes associated with the so-called critical form factors. (orig.)

  16. A low-temperature research facility for space

    International Nuclear Information System (INIS)

    Donnelly, R.J.

    1991-01-01

    The Jet Propulsion Laboratory is proposing to NASA a new initiative to construct a Low Temperature Research Facility for use in space. The facility is described, together with some details of timing and support. An advisory group has been formed which seeks to advise JPL and NASA of the capabilities required in this facility and to invite investigators to propose experiments which require the combination of low temperature and reduced gravity to be successful. (orig.)

  17. Corrosion test by low-temperature coal tar

    Energy Technology Data Exchange (ETDEWEB)

    Ando, S; Yamamoto, S

    1952-01-01

    Corrosive actions of various fractions of low-temperature coal tar against mild steel or Cr 13-steel were compared at their boiling states. Corrosions became severe when the boiling points exceeded 240/sup 0/. The acidic fractions were more corrosive. In all instances, corrosion was excessive at the beginning of immersion testing and then gradually became mild; boiling accelerated the corrosion. Cr 13-steel was corrosion-resistant to low-temperature coal-tar fractions.

  18. Innovative system for delivery of low temperature district heating

    OpenAIRE

    Ianakiev, A; Cui, JM; Garbett, S; Filer, A

    2017-01-01

    An innovative low temperature district heating (LTDH) local network is developed in Nottingham, supported by the REMOURBAN project, part of the H2020 Smart City and Community Lighthouse scheme. It was proposed that a branch emanating from the return pipe of the existing district heating system in Nottingham would be created to use low temperature heating for the first time on such scale in the UK. The development is aimed to extract unused heat from existing district heating system and to mak...

  19. On-line methanol sensor system development for recombinant ...

    African Journals Online (AJOL)

    PANCHIGA

    2016-10-19

    Oct 19, 2016 ... Calibration of the methanol sensor system was done in a medium environment with ... by taking protein induction at a low temperature and a pH where protease ... molecular weight of 66.5 kDa, HSA comprises about one-.

  20. Black Liquor Gasification with Motor Fuel Production - BLGMF II - A techno-economic feasibility study on catalytic Fischer-Tropsch synthesis for synthetic diesel production in comparison with methanol and DME as transport fuels

    Energy Technology Data Exchange (ETDEWEB)

    Ekbom, Tomas; Berglin, Niklas; Loegdberg, Sara [Nykomb Synergetics AB, Stockholm (Sweden)

    2005-06-15

    The present project presents additional results to the former BLGMF project, which investigate Black Liquor Gasification with Motor Fuels (BLGMF) production. The objectives were to investigate, based on the KAM 2 program Ecocyclic Pulp Mill (2,000 ADt/day of pulp) the feasibility of synthetic fuels production. Specifically the route to Fischer-Tropsch diesel fuels is investigated as comparison to earlier work on methanol/DME. As modern kraft pulp mills have a surplus of energy, they could become key suppliers of renewable fuels. It is thus of great interest to convert the spent cooking product 'black liquor' to an energy carrier of high value. The resulting biomass-to-fuel energy efficiency when only biomass is used as an external energy source was 43% for FTD or 65% for FT products compared with 66% for methanol and 67% for DME. The FTD calculation is considerably more complicated and based on assumptions, therefore the uncertainty is higher. Would the diesel be taken out with a T95% of 320 deg C the FTD efficiency would be 45%. FT synthesis also opens up a possibility to produce e.g. lube oils from waxes produced. The total net FT-products output equals 4115 barrels/day. The FTD production cost is calculated as the energy share of the total production cost and assumes an offset of naphtha covering its own costs, where it is essential that it finds a market. Assuming same petrol (methanol) and diesel (DME, FTD) costs for the consumer the payback time were 2.6, 2.9 and 3.4 years with an IRR of 40%, 45% and 30%, respectively. In conclusion, there are necessary resources and potential for large-scale methanol (or DME, FTD) production and substantial economic incentive for making plant investments and achieving competitive product revenues.

  1. Growth and Low Temperature Transport Measurements of Pure and Doped Bismuth Selenide

    DEFF Research Database (Denmark)

    Mlack, Jerome Thomas

    Se3, which is a strong spin orbit material and a topological insulator. I describe a synthesis technique and low-temperature transport measurements of nanostructures of Bi2Se3, that when annealed with palladium show evidence of superconductivity. The growth method is a catalyst-free atmospheric...... with palladium via annealing, the transport properties of the samples can be altered to exhibit superconductivity. Thin films of palladium are deposited on prefabricated Bi2Se3 nanodevices and annealed at temperatures in excess of 100 Celsius. We find that Bi2Se3 absorbs Pd under these conditions...... pressure vapor-solid growth. The growth method yields a variety of nanostructures, and materials analysis shows ordered structures of bismuth selenide in all cases. Low-temperature measurements of as-grown nanostructures indicate tunable carrier density in all samples. By doping the nanostructures...

  2. Low-temperature atomic layer deposition of MoS{sub 2} films

    Energy Technology Data Exchange (ETDEWEB)

    Jurca, Titel; Wang, Binghao; Tan, Jeffrey M.; Lohr, Tracy L.; Marks, Tobin J. [Department of Chemistry and the Materials Research Center, Northwestern University, Evanston, IL (United States); Moody, Michael J.; Henning, Alex; Emery, Jonathan D.; Lauhon, Lincoln J. [Department of Materials Science and Engineering, and the Materials Research Center, Northwestern University, Evanston, IL (United States)

    2017-04-24

    Wet chemical screening reveals the very high reactivity of Mo(NMe{sub 2}){sub 4} with H{sub 2}S for the low-temperature synthesis of MoS{sub 2}. This observation motivated an investigation of Mo(NMe{sub 2}){sub 4} as a volatile precursor for the atomic layer deposition (ALD) of MoS{sub 2} thin films. Herein we report that Mo(NMe{sub 2}){sub 4} enables MoS{sub 2} film growth at record low temperatures - as low as 60 C. The as-deposited films are amorphous but can be readily crystallized by annealing. Importantly, the low ALD growth temperature is compatible with photolithographic and lift-off patterning for the straightforward fabrication of diverse device structures. (copyright 2017 Wiley-VCH Verlag GmbH and Co. KGaA, Weinheim)

  3. Magnetic hyperthermia heating of cobalt ferrite nanoparticles prepared by low temperature ferrous sulfate based method

    Directory of Open Access Journals (Sweden)

    Tejabhiram Yadavalli

    2016-05-01

    Full Text Available A facile low temperature co-precipitation method for the synthesis of crystalline cobalt ferrite nanostructures using ferrous sulfate salt as the precursor has been discussed. The prepared samples were compared with nanoparticles prepared by conventional co-precipitation and hydrothermal methods using ferric nitrate as the precursor. X-ray diffraction studies confirmed the formation of cubic spinel cobalt ferrites when dried at 110 °C as opposed to conventional methods which required higher temperatures/pressure for the formation of the same. Field emission scanning electron microscope studies of these powders revealed the formation of nearly spherical nanostructures in the size range of 20-30 nm which were comparable to those prepared by conventional methods. Magnetic measurements confirmed the ferromagnetic nature of the cobalt ferrites with low magnetic remanance. Further magnetic hyperthermia studies of nanostructures prepared by low temperature method showed a rise in temperature to 50 °C in 600 s.

  4. New developments in low temperature physics New developments in low temperature physics

    Science.gov (United States)

    Hallock, Bob; Paalanenn, Mikko

    2009-04-01

    Below you will find part of the activity report to the IUPAP General Assembly, October 2008, by the present and previous Chairmen of C5. It provides an overview of the most important and recent developments in low temperature physics, much in line with the program of LT25. For the field of experimental low temperature physics, the ability to conduct research has been damaged by the dramatic increase in the price of liquid helium. In the USA, for example, the price of liquid helium has approximately doubled over the past two years. This has led to a reduction in activity in many laboratories as the funding agencies have not quickly increased support in proportion. The increase in price of liquid helium has accelerated interest in the development and use of alternative cooling systems. In particular, pulse-tube coolers are now available that will allow cryostats with modest cooling needs to operate dilution refrigerators without the need for repeated refills of liquid helium from external supply sources. Solid helium research has seen a dramatic resurgence. Torsional oscillator experiments have been interpreted to show that solid helium may undergo a transition to a state in which some of the atoms in the container do not follow the motion of the container, e.g. may be 'supersolid'. The observation is robust, but the interpretation is controversial. The shear modulus of solid helium undergoes a similar signature with respect to temperature. Experiments that should be expected to cause helium to flow give conflicting results. Theory predicts that a perfect solid cannot show supersolid behavior, but novel superfluid-like behavior should be seen in various defects that can exist in the solid, and vorticity may play a significant role. And, recently there have been reports of unusual mass decoupling in films of pure 4He on graphite surfaces as well as 3He- 4He mixture films on solid hydrogen surfaces. These may be other examples of unusual superfluid-like behavior. There

  5. Asymmetric Brønsted Acid Catalyzed Substitution of Diaryl Methanols with Thiols and Alcohols for the Synthesis of Chiral Thioethers and Ethers

    KAUST Repository

    Chatupheeraphat, Adisak; Liao, Hsuan-Hung; Mader, Steffen; Sako, Makoto; Sasai, Hiroaki; Atodiresei, Iuliana; Rueping, Magnus

    2016-01-01

    An enantioselective addition of thiols and alcohols to aza-ortho-quinone methides, starting from diaryl methanols, was developed. The asymmetric additions occur under mild reaction conditions in the presence of chiral phosphoric acids and furnish the corresponding adducts with excellent yields and enantioselectivities.

  6. Asymmetric Brønsted Acid Catalyzed Substitution of Diaryl Methanols with Thiols and Alcohols for the Synthesis of Chiral Thioethers and Ethers

    KAUST Repository

    Chatupheeraphat, Adisak

    2016-03-08

    An enantioselective addition of thiols and alcohols to aza-ortho-quinone methides, starting from diaryl methanols, was developed. The asymmetric additions occur under mild reaction conditions in the presence of chiral phosphoric acids and furnish the corresponding adducts with excellent yields and enantioselectivities.

  7. ONLINE SINGLE-COLUMN CAPILLARY GAS-CHROMATOGRAPHIC ANALYSIS OF ALL REACTANTS AND PRODUCTS IN THE SYNTHESIS OF FUEL METHANOL FROM HYDROGEN AND OXIDES OF CARBON

    NARCIS (Netherlands)

    MARSMAN, JH; BREMAN, BB; BEENACKERS, AACM

    The main problems with complete analysis of the components of fuel methanol, or in Fischer-Tropsch studies, are the several classes of compound present in the sample (permanent gases, water, alcohols, hydrocarbons), its wide range of components, its boiling point range, and the wide range of

  8. Simple one-pot synthesis of platinum-palladium nanoflowers with enhanced catalytic activity and methanol-tolerance for oxygen reduction in acid media

    International Nuclear Information System (INIS)

    Zheng, Jie-Ning; He, Li-Li; Chen, Fang-Yi; Wang, Ai-Jun; Xue, Meng-Wei; Feng, Jiu-Ju

    2014-01-01

    Graphical abstract: PtPd nanoflowers were fabricated by one-pot solvothermal co-reduction method in oleylamine system, which exhibited the improved electrocatalytic activity and higher methanol tolerance for oxygen reduction, compared with commercial Pt and Pd black catalysts. - Highlights: • Bimetallic alloyed PtPd nanoflowers are prepared by a simple one-pot solvothermal co-reduction method. • PtPd nanoflowers display high catalytic performance for ORR dominated by a four-electron pathway. • PtPd nanoflowers show good methanol tolerance for ORR. - Abstract: In this work, bimetallic alloyed platinum-palladium (PtPd) nanoflowers are fabricated by one-pot solvothermal co-reduction of Pt (II) acetylacetonate and Pd (II) acetylacetonate in oleylamine system. The as-prepared nanostructures show the enhanced electrocatalytic activity for oxygen reduction reaction (ORR), dominated by a four-electron pathway based on the Koutecky-Levich plots, mainly owing to the inhibition of the formation of Pt–OH ad via the downshift of d-band center for Pt. Meanwhile, PtPd nanoflowers display good methanol tolerance and improved stability for ORR. The chronoamperometry test reveals that the current of PtPd nanoflowers remains 45.9% of its original value within 6000 s, much higher than those of commercial Pt (36.7%) and Pd (32.2%) black catalysts. Therefore, PtPd nanoflowers with unique interconnected structures can be used as a promising cathode catalyst in direct methanol fuel cells

  9. Synthesis and properties of a novel sulfonated poly(arylene ether ketone sulfone) membrane with a high β-value for direct methanol fuel cell applications

    International Nuclear Information System (INIS)

    Xu, Jingmei; Ma, Li; Han, Hailan; Ni, Hongzhe; Wang, Zhe; Zhang, Huixuan

    2014-01-01

    Highlights: • Introduction of carboxyl groups into copolymers resulted in extensive hydrogen bond. • The C-SPAEKS membranes had obviously hydrophilic/hydrophobic phase separation. • The membranes showed low methanol permeability and high β values. • The membranes exhibited good thermal property and desirable mechanical performance. - Abstract: Sulfonated poly(arylene ether ketone sulfone) membranes containing carboxylic acid groups (C-SPAEKS) with different degrees of sulfonation were synthesized by the nucleophilic aromatic substitution reactions of 4-carboxylphenyl hydroquinone (4C-PH), bisphenol A, 3,3′-disulfonated 4,4′-dichlorodiphenyl sulfone, and 4,4′-difluorobenzophenone. The Fourier transform infrared and 1 H NMR analyses of C-SPAEKS revealed the presence of carboxylic acid groups in the C-SPAEKS membranes. The membranes exhibited a low swelling degree and methanol crossover level. The effects of different degrees of sulfonation on the water uptake, proton conductivity, and methanol permeability coefficient of the membranes were studied. The maximum proton conductivity of C-SPAEKS-80 membrane at room temperature was 0.069 S cm −1 , which was higher than that of Nafion ® 117 membrane. The methanol permeability coefficient of C-SPAEKS-80 membrane was 9.15 × 10 −7 cm 2 s −1 at 20 °C, much lower than that of Nafion 117 membrane (22.9 × 10 −7 cm 2 s −1 ). Furthermore, the carboxyl group-containing membranes exhibited a high β-value, further confirming that this series of membranes possess excellent comprehensive performance and can be applied in direct methanol fuel cells

  10. Methanol Fuel Cell

    Science.gov (United States)

    Voecks, G. E.

    1985-01-01

    In proposed fuel-cell system, methanol converted to hydrogen in two places. External fuel processor converts only part of methanol. Remaining methanol converted in fuel cell itself, in reaction at anode. As result, size of fuel processor reduced, system efficiency increased, and cost lowered.

  11. Experimental analysis of methanol cross-over in a direct methanol fuel cell

    Energy Technology Data Exchange (ETDEWEB)

    Casalegno, Andrea [Dipartimento di Energetica, Politecnico di Milano, Piazza Leonardo da Vinci 32, 20133 Milan (Italy)]. E-mail: andrea.casalegno@polimi.it; Grassini, Paolo [Dipartimento di Energetica, Politecnico di Milano, Piazza Leonardo da Vinci 32, 20133 Milan (Italy)]. E-mail: PGrassini@seal.it; Marchesi, Renzo [Dipartimento di Energetica, Politecnico di Milano, Piazza Leonardo da Vinci 32, 20133 Milan (Italy)]. E-mail: renzo.marchesi@polimi.it

    2007-03-15

    Methanol cross-over through the polymeric membrane is one of the main causes limiting direct methanol fuel cell performances. It causes fuel wasting and enhances cathode overpotential. A repeatable and reproducible measurement system, that assures the traceability of the measurement to international reference standards, is necessary to compare different fuel cell construction materials. In this work a method to evaluate methanol cross-over rate and operating condition influence is presented and qualified in term of measurement uncertainty. In the investigated range, the methanol cross-over rate results mainly due to diffusion through the membrane, in fact it is strongly affected by temperature. Moreover the cross-over influence on fuel utilization and fuel cell efficiency is investigated. The methanol cross-over rate appears linearly proportional to electrochemical fuel utilization and values, obtained by measurements at different anode flow rate but constant electrochemical fuel utilization, are roughly equal; methanol wasting, due to cross-over, is considerable and can still be higher than electrochemical utilization. The fuel recirculation effect on energy efficiency has been investigated and it was found that fuel recirculation gives more advantage at low temperature, but fuel cell energy efficiency results are in any event higher at high temperature.

  12. Experimental analysis of methanol cross-over in a direct methanol fuel cell

    International Nuclear Information System (INIS)

    Casalegno, Andrea; Grassini, Paolo; Marchesi, Renzo

    2007-01-01

    Methanol cross-over through the polymeric membrane is one of the main causes limiting direct methanol fuel cell performances. It causes fuel wasting and enhances cathode overpotential. A repeatable and reproducible measurement system, that assures the traceability of the measurement to international reference standards, is necessary to compare different fuel cell construction materials. In this work a method to evaluate methanol cross-over rate and operating condition influence is presented and qualified in term of measurement uncertainty. In the investigated range, the methanol cross-over rate results mainly due to diffusion through the membrane, in fact it is strongly affected by temperature. Moreover the cross-over influence on fuel utilization and fuel cell efficiency is investigated. The methanol cross-over rate appears linearly proportional to electrochemical fuel utilization and values, obtained by measurements at different anode flow rate but constant electrochemical fuel utilization, are roughly equal; methanol wasting, due to cross-over, is considerable and can still be higher than electrochemical utilization. The fuel recirculation effect on energy efficiency has been investigated and it was found that fuel recirculation gives more advantage at low temperature, but fuel cell energy efficiency results are in any event higher at high temperature

  13. Methanol production from eucalyptus wood chips. Attachment IV. Health and safety aspects of the eucalypt biomass to methanol energy system

    Energy Technology Data Exchange (ETDEWEB)

    Fishkind, H.H.

    1982-06-01

    The basic eucalyptus-to-methanol energy process is described and possible health and safety risks are identified at all steps of the process. The toxicology and treatment for exposure to these substances are described and mitigating measures are proposed. The health and safety impacts and risks of the wood gasification/methanol synthesis system are compared to those of the coal liquefaction and conversion system. The scope of this report includes the health and safety risks of workers (1) in the laboratory and greenhouse, where eucalyptus seedlings are developed, (2) at the biomass plantation, where these seedlings are planted and mature trees harvested, (3) transporting these logs and chips to the refinery, (4) in the hammermill, where the logs and chips will be reduced to small particles, (5) in the methanol synthesis plant, where the wood particles will be converted to methanol, and (6) transporting and dispensing the methanol. Finally, the health and safety risks of consumers using methanol is discussed.

  14. PVA assisted low temperature anatase to rutile phase transformation (ART) and properties of titania nanoparticles

    International Nuclear Information System (INIS)

    Mondal, Shrabani; Madhuri, Rashmi; Sharma, Prashant K.

    2015-01-01

    Anatase to rutile phase transformation (ART) of titania nanoparticles is observed at very low temperature (180 °C) just by introducing polyvinyl alcohol (PVA) during co-precipitation followed by hydrothermal synthesis. The detailed investigations pertaining to the structural, optical and electrochemical properties of the nanosized titania and titania/PVA nanohybrid has been carried out. The crystallite size and crystal structure is confirmed using X-ray diffraction (XRD). Transmission electron microscopic (TEM) image reveals formation of spherical NPs in both the cases. Identification of functional groups is done using Fourier transform infrared spectroscopy (FTIR). The photoluminescence studies showed that emission slightly shifts towards higher wavelength side with remarkable decrease in intensity for TiO 2 /PVA nanocomposite (rutile samples). The remarkable decrease in PL intensity in TiO 2 /PVA nanocomposite (rutile samples) is explained considering the surface passivation during growth process. Ion transportation is monitored via Cyclic voltammetric (CV) and Electrochemical Impedance Spectroscopy (EIS) measurements. A significant enhancement of peak cathodic current in case of nanocomposite modified electrode is observed. It is assumed that TiO 2 /PVA (rutile) nanoparticles provided the conducting path for the electrons and hence enhanced the electrochemical reaction. - Graphical abstract: Present work reports anatase to rutile phase transformation (ART) of titania nanoparticles at very low temperature (180 °C) just by introducing polyvinyl alcohol (PVA) during co-precipitation followed by hydrothermal synthesis. - Highlights: • Low temperature phase transformation of TiO 2 nanoparticles from anatase to rutile. • Role of PVA in phase transformation. • Synthesis of spherical shaped uniformly distributed PVA capped TiO 2 NPs. • Explained the charge transfer process among anatase to rutile phase transformation via luminescence studies. • Enhanced

  15. Design for a low temperature ion implantation and luminescence cryostat

    International Nuclear Information System (INIS)

    Noonan, J.R.; Kirkpatrick, C.G.; Myers, D.R.; Streetman, B.G.

    1976-01-01

    Several simple design changes of a conventional liquid helium optical Dewar can significantly improve the cryostat's versatility for use in low temperature particle irradiation. A bellows assembly provides precise sample positioning and allows convenient access for electrical connections. A heat exchanger consisting of thin walled tubing with a 'goose neck' bend provides a simple, effective means of cooling the sample as well as excellent thermal isolation of the sample holder from the coolant reservoir during controlled anneals. The addition of a vane-type vacuum valve, optical windows, and a rotatable tailpiece facilitates the study of optical properties of materials following low temperature ion implantation. (author)

  16. Heat Transfer and Cooling Techniques at Low Temperature

    CERN Document Server

    Baudouy, B

    2014-07-17

    The first part of this chapter gives an introduction to heat transfer and cooling techniques at low temperature. We review the fundamental laws of heat transfer (conduction, convection and radiation) and give useful data specific to cryogenic conditions (thermal contact resistance, total emissivity of materials and heat transfer correlation in forced or boiling flow for example) used in the design of cooling systems. In the second part, we review the main cooling techniques at low temperature, with or without cryogen, from the simplest ones (bath cooling) to the ones involving the use of cryocoolers without forgetting the cooling flow techniques.

  17. Instrument for Measuring Thermal Conductivity of Materials at Low Temperatures

    Science.gov (United States)

    Fesmire, James; Sass, Jared; Johnson, Wesley

    2010-01-01

    With the advance of polymer and other non-metallic material sciences, whole new series of polymeric materials and composites are being created. These materials are being optimized for many different applications including cryogenic and low-temperature industrial processes. Engineers need these data to perform detailed system designs and enable new design possibilities for improved control, reliability, and efficiency in specific applications. One main area of interest is cryogenic structural elements and fluid handling components and other parts, films, and coatings for low-temperature application. An important thermal property of these new materials is the apparent thermal conductivity (k-value).

  18. Heat Transfer and Cooling Techniques at Low Temperature

    Energy Technology Data Exchange (ETDEWEB)

    Baudouy, B [Saclay (France)

    2014-07-01

    The first part of this chapter gives an introduction to heat transfer and cooling techniques at low temperature. We review the fundamental laws of heat transfer (conduction, convection and radiation) and give useful data specific to cryogenic conditions (thermal contact resistance, total emissivity of materials and heat transfer correlation in forced or boiling flow for example) used in the design of cooling systems. In the second part, we review the main cooling techniques at low temperature, with or without cryogen, from the simplest ones (bath cooling) to the ones involving the use of cryocoolers without forgetting the cooling flow techniques.

  19. Synthesis of Hβ (core)/SAPO-11 (shell) Composite Molecular Sieve and its Catalytic Performances in the Methylation of Naphthalene with Methanol

    International Nuclear Information System (INIS)

    Wang, Xiaoxiao; Zhao, Liangfu; Guo, Shaoqing

    2013-01-01

    Hβ (core)/SAPO-11 (shell) composite molecular sieve was synthesized by the hydrothermal method in order to combine the advantages of Hβ and SAPO-11 for the methylation of naphthalene with methanol. For comparison, the mechanical mixture was prepared through the blending of Hβ and SAPO-11. The physicochemical properties of Hβ, SAPO-11, the composite and the mechanical mixture were characterized by various characterization methods. The characterization results indicated that Hβ/SAPO-11 composite molecular sieve exhibited a core-shell structure, with the Hβ phase as the core and the SAPO-11 phase as the shell. The pore diameter of the composite was between that of Hβ and SAPO-11. The composite had fewer acid sites than Hβ and mechanical mixture while more acid sites than SAPO-11. The experimental results indicated that the composite exhibited high catalytic performances for the methylation of naphthalene with methanol

  20. Direct synthesis of bimetallic PtCo mesoporous nanospheres as efficient bifunctional electrocatalysts for both oxygen reduction reaction and methanol oxidation reaction

    Science.gov (United States)

    Wang, Hongjing; Yu, Hongjie; Li, Yinghao; Yin, Shuli; Xue, Hairong; Li, Xiaonian; Xu, You; Wang, Liang

    2018-04-01

    The engineering of electrocatalysts with high performance for cathodic and/or anodic catalytic reactions is of great urgency for the development of direct methanol fuel cells. Pt-based bimetallic alloys have recently received considerable attention in the field of fuel cells because of their superior catalytic performance towards both fuel molecule electro-oxidation and oxygen reduction. In this work, bimetallic PtCo mesoporous nanospheres (PtCo MNs) with uniform size and morphology have been prepared by a one-step method with a high yield. The as-made PtCo MNs show superior catalytic activities for both oxygen reduction reaction and methanol oxidation reaction relative to Pt MNs and commercial Pt/C catalyst, attributed to their mesoporous structure and bimetallic composition.