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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. Continuous low-temperature methanol synthesis from syngas using alcohol promoters

    Energy Technology Data Exchange (ETDEWEB)

    Prasert Reubroycharoen; Tetsuji Yamagami; Tharapong Vitidsant; Yoshiharu Yoneyama; Motoaki Ito; Noritatsu Tsubaki [Toyama University, Toyama (Japan). Department of Material System & Life Science, School of Engineering

    2003-08-01

    Continuous low-temperature methanol synthesis from syngas containing CO{sub 2} on various Cu/ZnO catalysts was investigated by using a semibatch autoclave reactor. Methanol was easily produced at a temperature as low as 443 K and with a pressure of 50 bar with the aid of 2-butanol, which showed a very high efficiency with a one-pass yield of 47.0% and a selectivity of 98.9%. Methanol itself used as alcohol promoter exhibited a higher activity than other 1-alcohols because it has the lowest spatial effect. 2-Alcohols, however, exhibited the highest conversion among the same carbon number because of its well-balanced effects produced by their of electronic and spatial factors. The one-pass conversion was improved by increasing the catalyst weight because no thermodynamic limitations existed at low temperatures. The continuous low-temperature methanol synthesis is a very promising process because completely purified syngas is not necessary. 23 refs., 3 figs., 4 tabs.

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

    Directory of Open Access Journals (Sweden)

    Christian Ahoba-Sam

    2017-07-01

    Full Text Available 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 SiO2 catalyst used dictated trend of syngas conversion. Diglyme with a dielectric constant (ɛ = 7.2 gave the highest syngas conversion among the eight different solvents used. Methanol formation decreased with either increasing or decreasing solvent ɛ value of diglyme (ɛ = 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. New process of low-temperature methanol synthesis from CO/CO2/H2 based on dual-catalysis

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    A new process of low-temperature methanol synthesis from CO/CO2/H2 based on dual-catalysis has been developed. Some alcohols, especially 2-alcohol, were found to have high cata-lytic promoting effect on the synthesis of methanol from CO hydrogenation. At 443 K and 5 MPa, the synthesis of methanol could process high effectively, resulting from the synergic catalysis of Cu/ZnO solid catalyst and 2-alcohol solvent catalyst. The primary results showed that when 2-butanol was used as reaction solvent, the one-pass average yield and the selectivity of methanol, in 40 h con-tinuous reaction at temperature as low as 443 K and 5 MPa, were high up to 46.51% and 98.94% respectively. The catalytic activity was stable and the reaction temperature was 80 K or so lower than that in current industry synthesis process. This new process hopefully will become a practical method for methanol synthesis at low temperature.

  6. New process of low-temperature methanol synthesis from CO/CO2/H2 based on dual-catalysis

    Institute of Scientific and Technical Information of China (English)

    曾健青; TSUBAKINoritatsu; FUJIMOTOKaoru

    2002-01-01

    A new process of low-temperature methanol synthesis from CO/CO2/H2 based on dual-catalysis has been developed. Some alcohols, especially 2-alcohol, were found to have high catalytic promoting effect on the synthesis of methanol from CO hydrogenation. At 443 K and 5 MPa, the synthesis of methanol could process high effectively, resulting from the synergic catalysis of Cu/ZnO solid catalyst and 2-alcohol solvent catalyst. The primary results showed that when 2-butanol was used as reaction solvent, the one-pass average yield and the selectivity of methanol, in 40 h continuous reaction at temperature as low as 443 K and 5 MPa, were high up to 46.51% and 98.94% respectively. The catalytic activity was stable and the reaction temperature was 80 K or so lower than that in current industry synthesis process. This new process hopefully will become a practical method for methanol synthesis at low temperature.

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

    DEFF Research Database (Denmark)

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

    is subsequently increased, suggesting the presence of carbon containing species blocking the active sites of the alloy nanoparticles (Figure 1). Carbon deposition has furthermore been investigated by temperature programmed oxidation (TPO) of a deactivated catalyst in a fixed-bed reactor connected to a mass......-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...... as catalyst for methanol production. Synthesis, followed by deactivation and a series of regeneration steps at increasing temperature in pure H2 has been carried out in a fixed-bed reactor connected to a gas chromatography system. In each regeneration step, CH4 is generated and the activity of the catalyst...

  8. An introduction of CO₂ conversion by dry reforming with methane and new route of low-temperature methanol synthesis.

    Science.gov (United States)

    Shi, Lei; Yang, Guohui; Tao, Kai; Yoneyama, Yoshiharu; Tan, Yisheng; Tsubaki, Noritatsu

    2013-08-20

    converted in situ via one of two main routes. The first is to use Fischer-Tropsch synthesis (FTS), a process that catalytically converts syngas to hydrocarbons of varying molecular weights. The second is methanol synthesis. The latter has better atomic economy, since the oxygen atom in CO is included in the product and CO₂ can be blended into syngas as a reactant. However, production of methanol is very inefficient in this reaction: only 10-15% one-pass conversion typically at 5.0-10.0 MPa and 523-573 K, due to the severe thermodynamic limitations of this exothermal reaction (CO + 2H₂ = CH₃OH). In this Account, we propose and develop a new route of low-temperature methanol synthesis from CO₂-containing syngas only by adding alcohols, including methanol itself. These alcohols act as homogeneous cocatalysts and the solvent, realizing 70-100% one-pass conversion at only 5.0 MPa and 443 K. The key step is the reaction of the adsorbed formate species with alcohols to yield ester species at low temperatures, followed by the hydrogenation of ester by hydrogen atoms on metallic Cu. This changes the normal reaction path of conventional, high-temperature methanol synthesis from formate via methoxy to methanol.

  9. 低温甲醇合成研究进展%Research developments of low-temperature methanol synthesis

    Institute of Scientific and Technical Information of China (English)

    石磊; 张婉莹; 王玉鑫; TsubakiNoritatsu

    2015-01-01

    Conventional production of methanol is very inefficient since only 10%—15% one-pass conversion is achieved typically at 5.0—10.0 MPa and 523—573 K due to the severe thermodynamic limitations of its exothermal reaction (CO + 2H2 = CH3OH). A novel route of low-temperature methanol synthesis developed by Tsubaki et al from CO2-containing syngas only by adding alcohols including methanol itself is reviewed. These alcohols act as the homogeneous co-catalysts and solvent, realizing 70%—100% one-pass conversion at only 5.0 MPa and 443 K. The key step is the reaction of the adsorbed formate species with alcohols to yield ester species at low temperatures, followed by the hydrogenation of ester by hydrogen atoms on metallic Cu. This changes the normal reaction path of conventional, high-temperature methanol synthesis from formate via methoxy to methanol. A series of new methods, such as sol-gel auto-combustion, solid-state combustion and formic acid assisted combustion methods, to prepare highly active metallic Cu/ZnO catalysts without further reduction are also reviewed. During the decomposition of metal-contained precursors in an argon atmosphere, H2 and CO are liberated and act in situ as the reducing agents to obtain pure metals and metallic catalysts. The X-ray diffraction, X-ray photoelectron spectroscopy, energy dispersive spectroscopy, and temperature-programmed reduction analysis reveal that the as-prepared catalyst without further reduction is converted into metallic Cu0 and ZnO species.%日本学者 Tsubaki 等开创了一种全新的低温甲醇合成反应路径.该路径以含有二氧化碳的合成气为反应原料,使用单一低碳醇(包括甲醇)同时作为催化剂和溶剂,实现了反应原料一氧化碳在低温(443 K)条件下,一步转化率达到 70%~100%.原位红外和多种表征手段证明,该反应能够在低温条件下进行,是由于催化剂上吸附的甲酸盐物种可以和多种低碳醇溶剂在低温条件发生酯化

  10. Study on photocatalysis of TiO2 nanotubes prepared by methanol-thermal synthesis at low temperature

    Indian Academy of Sciences (India)

    Chau Thanh Nam; Wein-Duo Yang; Le Minh Duc

    2013-10-01

    TiO2 nanotubes were synthesized by the solvothermal process at low temperature in a highly alkaline water–methanol mixed solution. Their characteristics were identified by powder X-ray diffraction (XRD), transmission electron microscopy (TEM), specific surface area (BET), Fourier transform infrared spectroscopy (FTIR) and UV–Vis absorption spectroscopy. The as-prepared samples were tested by the photodegradation reaction of methylene blue (MB) dye under visible-light irradiation. The ratios of methanol and water, as well as calcination temperature, affected the morphology, nanostructure and photocatalytic performance. The methanol solvent plays an important role in improving crystallization of the anatase phase, which affects the photocatalytic reaction. Titanate nanotubes were synthesized in methanol–water volume ratios of 10:90, 20:80 and 30:70 which still had high absorbability. Titania nanotubes formed at a calcination temperature of 300 °C using methanol–water volume ratio of 30:70 showed highest photocatalytic performance, much higher than that using water solvent and TiO2–P25 powder.

  11. Promoting effect of polyoxyethylene octylphenol ether on Cu/ZnO catalysts for low-temperature methanol synthesis

    Institute of Scientific and Technical Information of China (English)

    Ling Liu; Tiansheng Zhao; Qingxiang Ma; Yufang Shen

    2009-01-01

    Cu/ZnO catalysts were prepared by the co-precipitation method with the addition of OP-10 (polyoxyethylene octyiphenol ether) and were chemically and structurally characterized by means of XRD,BET,H_2-TPR,CO-TPD and N_2O-titration. The effect of OP-10 addition on the activity of Cu/ZnO for the slurry phase methanol synthesis at 150 ℃ was evaluated. The results showed that Cu/ZnO prepared with addition of 8% OP-10 (denoted as C8) exhibited the promoted activity for the methanol synthesis. The conversion of CO and the STY (space time yield) of methanol were 42.5% and 74.6% higher than those of Cu/ZnO prepared without addition of OP-10 (denoted as CO),respectively. The precursor of C8 contained more aurichalcite and rosasite,and the concerted effect of Cu-Zn in C8 was found to be stronger than that in CO. Compared with CO,C8 showed smaller particle size,lower reduction temperature and larger BET and Cu surface areas.

  12. 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........ In contrast to the biological process, the industrial process requires high temperatures and pressures to proceed, and an explanation of this important difference is discussed. The possibility of a metal surface catalyzed process running at low temperatures and pressures is addressed, and DFT calculations...

  13. Low temperature synthesis of porous silicate ceramics

    OpenAIRE

    Méndez Enríquez Y.; Vlasova M.; Leon I.; Kakazey M.G.; Dominguez-Patiño M.; Isaeva L.; Tomila T.

    2007-01-01

    Impregnation of a polyurethane sponge with kaolin, feldspar, silica, fusible glass slurry followed by temperature treatment in air in the temperature range 800-1000 0 C leads to the formation of aluminosilicate ceramics with a set pore size. The low-temperature synthesis of porous ceramics is based on the stage-by-stage formation of low-temperature eutectics and thermodestruction of polyurethane sponge.

  14. Low temperature synthesis of porous silicate ceramics

    Directory of Open Access Journals (Sweden)

    Méndez Enríquez Y.

    2007-01-01

    Full Text Available Impregnation of a polyurethane sponge with kaolin, feldspar, silica, fusible glass slurry followed by temperature treatment in air in the temperature range 800-1000 0 C leads to the formation of aluminosilicate ceramics with a set pore size. The low-temperature synthesis of porous ceramics is based on the stage-by-stage formation of low-temperature eutectics and thermodestruction of polyurethane sponge.

  15. 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.

  16. Cu/MgO催化剂CO加氢低温甲醇合成研究%LOW-TEMPERATURE METHANOL SYNTHESIS FROM CO HYDROGENATION OVER Cu/MgO CATALYST

    Institute of Scientific and Technical Information of China (English)

    张建利; 邵光涛; 马利海; 沈玉芳; 赵天生; 李文怀

    2013-01-01

    采用共沉淀法制备了Cu/MgO催化剂并经La和K修饰,研究了含CO2的CO原料气加氢低温甲醇合成性能.采用XRD,CO-TPD和CO2-TPD等手段对催化剂的物相结构和表面吸附行为进行了表征.结果表明,La的添加促进了Cu组分的分散,增强了CO和CO2低温吸附能力,CO2加氢活性提高;进一步经K修饰后,催化剂表面碱性明显增强,CO和CO2高温吸附能力增强,促使CO和CO2同步转化,催化活性和甲醇收率明显提高,但副产物甲酸乙酯含量增加;当n(Cu)∶n(K)为10∶1时,总碳转化率达29.7%,甲醇收率较高,且催化剂具有较好的稳定性.%La and K promoted Cu/MgO catalysts were prepared by coprecipitation method. The catalytic performance of the catalysts on low-temperature methanol synthesis from CO2 -containing syngas was investigated. The catalysts were characterized by means of XRD and TPD measurements. The results indicated that La2O3 addition improved Cu dispersion, which enhanced the low temperature CO and CO2 adsorption ability and promoted the conversion of CO2. With the further addition of K2O, the improved surface basicity caused an increase in CO and CO2 high temperature adsorption. The simultaneous conversion of CO and CO2 was achieved, and the activities of the catalyst and methanol yields were enhanced, while the selectivity of ethyl formate was increased. The catalyst with Cu/K molar ratio of 10 :1 showed high activity and stability, and the total carbon conversion of 29. 7% was obtained with high methanol yield.

  17. Methanol Uptake By Low Temperature Aqueous Sulfuric Acid Solutions

    Science.gov (United States)

    Iraci, Laura T.; Essin, Andrew M.; Golden, David M.; Hipskind, R. Stephen (Technical Monitor)

    2001-01-01

    To evaluate the role of upper tropospheric and lower stratospheric aerosols in the global budget of methanol, the solubility and reactivity of CH3OH in aqueous sulfuric acid solutions are under investigation. Using standard uptake techniques in a Knudsen cell reactor, we have measured the effective Henry's law coefficient, H(*), for methanol dissolution into 45 to 70 percent by weight H2SO4. We find that methanol solubility ranges from 10(exp 5) to 10(exp 8) M/atm and increases with decreasing temperature and with increasing sulfuric acid content. These solubility measurements include uptake due to physical solvation and all rapid equilibria which are established in solution. Our data indicate that simple uptake by aqueous sulfuric acid particles will not be a significant sink for methanol in the UT/LS. These results differ from those recently reported in the literature, and an explanation of this disparity will be presented. In addition to solvation, reaction between primary alcohols and sulfuric acid does occur, leading to the production of alkyl sulfates. Literature values for the rate of this reaction suggest that formation of CH3OSO3H may proceed in the atmosphere but is not significant under our experimental conditions. Results obtained using a complementary equilibrium measurement technique confirm this directly. In addition, the extent of methanol sequestration via formation of mono- and dimethylsulfate will be evaluated under several atmospheric conditions.

  18. Two-step method preparation of graphene without hydrogen on methanol pretreatment copper substrate by PECVD at low temperature

    Science.gov (United States)

    Han, Linzhi; Liu, JingJing; Zhao, Zhanxia; Chen, Shumin; Ma, Zhongquan; Zhao, Lei

    2016-10-01

    Plasma enhanced chemical vapor deposition (PECVD) is one effective method to prepare graphene at low temperature in a short time. However, the low temperature in PECVD could not provide substrate a proper state for large area and few layer graphene preparation. Herein, we propose a two-step method to grow graphene on Cu foils. In the first step, in order to acquire a smooth and oxide-free surface state, methanol was used as a reductant to pretreat Cu. In the second step, graphene films were prepared on Cu foils by PECVD using CH4 as carbon source with H2-free. Few-layer graphene sheets with diameter about 1 μm under low temperature (700 °C) and at a short time (10 min) on well pretreated Cu foils were successfully gotten. The effect of methanol pretreatment on graphene synthesis and the graphene growth mechanism on Cu substrate by PECVD are analyzed comprehensively.

  19. Synthesis of Carbon Nanotubes by MWPCVD at Low Temperature

    Institute of Scientific and Technical Information of China (English)

    王升高; 汪建华; 王传新; 马志彬; 满卫东

    2002-01-01

    Growth of carbon nanotubes (CNTs) at low temperature is very important to the applications of nanotubes. In this paper, under the catalytic effect of cobalt nanoparticles supported by SiO2, CNTs were synthesized by microwave plasma chemical vapor deposition (MWPCVD)below 500℃. It demonstrates that MWPCVD can be a very efficient process for the synthesis of CNTs at low temperature.

  20. Viscosity and density of methanol/water mixtures at low temperatures

    Science.gov (United States)

    Austin, J. G.; Kurata, F.; Swift, G. W.

    1968-01-01

    Viscosity and density are measured at low temperatures for three methanol/water mixtures. Viscosity is determined by a modified falling cylinder method or a calibrated viscometer. Density is determined by the volume of each mixture contained in a calibrated glass cell placed in a constant-temperature bath.

  1. Low-temperature hydrogen production from water and methanol using Pt/α-MoC catalysts.

    Science.gov (United States)

    Lin, Lili; Zhou, Wu; Gao, Rui; Yao, Siyu; Zhang, Xiao; Xu, Wenqian; Zheng, Shijian; Jiang, Zheng; Yu, Qiaolin; Li, Yong-Wang; Shi, Chuan; Wen, Xiao-Dong; Ma, Ding

    2017-03-22

    Polymer electrolyte membrane fuel cells (PEMFCs) running on hydrogen are attractive alternative power supplies for a range of applications, with in situ release of the required hydrogen from a stable liquid offering one way of ensuring its safe storage and transportation before use. The use of methanol is particularly interesting in this regard, because it is inexpensive and can reform itself with water to release hydrogen with a high gravimetric density of 18.8 per cent by weight. But traditional reforming of methanol steam operates at relatively high temperatures (200-350 degrees Celsius), so the focus for vehicle and portable PEMFC applications has been on aqueous-phase reforming of methanol (APRM). This method requires less energy, and the simpler and more compact device design allows direct integration into PEMFC stacks. There remains, however, the need for an efficient APRM catalyst. Here we report that platinum (Pt) atomically dispersed on α-molybdenum carbide (α-MoC) enables low-temperature (150-190 degrees Celsius), base-free hydrogen production through APRM, with an average turnover frequency reaching 18,046 moles of hydrogen per mole of platinum per hour. We attribute this exceptional hydrogen production-which far exceeds that of previously reported low-temperature APRM catalysts-to the outstanding ability of α-MoC to induce water dissociation, and to the fact that platinum and α-MoC act in synergy to activate methanol and then to reform it.

  2. Low-temperature hydrogen production from water and methanol using Pt/α-MoC catalysts

    Science.gov (United States)

    Lin, Lili; Zhou, Wu; Gao, Rui; Yao, Siyu; Zhang, Xiao; Xu, Wenqian; Zheng, Shijian; Jiang, Zheng; Yu, Qiaolin; Li, Yong-Wang; Shi, Chuan; Wen, Xiao-Dong; Ma, Ding

    2017-03-01

    Polymer electrolyte membrane fuel cells (PEMFCs) running on hydrogen are attractive alternative power supplies for a range of applications, with in situ release of the required hydrogen from a stable liquid offering one way of ensuring its safe storage and transportation before use. The use of methanol is particularly interesting in this regard, because it is inexpensive and can reform itself with water to release hydrogen with a high gravimetric density of 18.8 per cent by weight. But traditional reforming of methanol steam operates at relatively high temperatures (200-350 degrees Celsius), so the focus for vehicle and portable PEMFC applications has been on aqueous-phase reforming of methanol (APRM). This method requires less energy, and the simpler and more compact device design allows direct integration into PEMFC stacks. There remains, however, the need for an efficient APRM catalyst. Here we report that platinum (Pt) atomically dispersed on α-molybdenum carbide (α-MoC) enables low-temperature (150-190 degrees Celsius), base-free hydrogen production through APRM, with an average turnover frequency reaching 18,046 moles of hydrogen per mole of platinum per hour. We attribute this exceptional hydrogen production—which far exceeds that of previously reported low-temperature APRM catalysts—to the outstanding ability of α-MoC to induce water dissociation, and to the fact that platinum and α-MoC act in synergy to activate methanol and then to reform it.

  3. 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.

  4. Isothermal Cyclic Conversion of Methane into Methanol over Copper-Exchanged Zeolite at Low Temperature.

    Science.gov (United States)

    Tomkins, Patrick; Mansouri, Ali; Bozbag, Selmi E; Krumeich, Frank; Park, Min Bum; Alayon, Evalyn Mae C; Ranocchiari, Marco; van Bokhoven, Jeroen A

    2016-04-25

    Direct partial oxidation of methane into methanol is a cornerstone of catalysis. The stepped conversion of methane into methanol currently involves activation at high temperature and reaction with methane at decreased temperature, which limits applicability of the technique. The first implementation of copper-containing zeolites in the production of methanol directly from methane is reported, using molecular oxygen under isothermal conditions at 200 °C. Copper-exchanged zeolite is activated with oxygen, reacts with methane, and is subsequently extracted with steam in a repeated cyclic process. Methanol yield increases with methane pressure, enabling reactivity with less reactive oxidized copper species. It is possible to produce methanol over catalysts that were inactive in prior state of the art systems. Characterization of the activated catalyst at low temperature revealed that the active sites are small clusters of copper, and not necessarily di- or tricopper sites, indicating that catalysts can be designed with greater flexibility than formerly proposed. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  5. Solution-phase synthesis of nanomaterials at low temperature

    Institute of Scientific and Technical Information of China (English)

    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.

  6. Synthesis of nanocrystalline rutile-phase titania at low temperatures

    OpenAIRE

    SANTOS, Jorge Gomes dos; Ogasawara,Tsuneharu; CORRÊA, Ronaldo Antonio

    2009-01-01

    Anatase and rutile are the predominant phases in titanium dioxide. In many cases, rutile stable phase is the desired product material, but at low temperatures methods of synthesis (aqueous route) produce metastable anatase as a major product that reverts to rutile only when heated up to 1000 °C. Calcination for obtaining rutile phase is the greatest energy demanding step for titanium dioxide production by the sulphate process, and is responsible for almost 60% of total energy consumption. In ...

  7. 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

  8. 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....... Among them, Ni-Ga has been chosen, primarily due to low price of constituent metals. After the preliminary optimization work, an optimal catalyst composition and preparation method has been suggested. Indeed, for an optimal catalyst, which is a SiO2 supported Ni-Ga prepared from a solution of nitrates...... due to carbon formation) and under accelerated ageing conditions (due to dealloying). However, the initial activity could always be restored after treatment in hydrogen flow at elevated temperatures. The work in the direction of suppression of deactivation and by-product formation is still in progress....

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

    Science.gov (United States)

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

    2016-06-22

    The direct catalytic conversion of methane to liquid oxygenated compounds, such as methanol or dimethyl ether, at low temperature using molecular oxygen is a grand challenge in C-H activation that has never been met with synthetic, heterogeneous catalysts. We report the first demonstration of direct, catalytic oxidation of methane into methanol with molecular oxygen over copper-exchanged zeolites at low reaction temperatures (483-498 K). Reaction kinetics studies show sustained catalytic activity and high selectivity for a variety of commercially available zeolite topologies under mild conditions (e.g., 483 K and atmospheric pressure). Transient and steady state measurements with isotopically labeled molecules confirm catalytic turnover. The catalytic rates and apparent activation energies are affected by the zeolite topology, with caged-based zeolites (e.g., Cu-SSZ-13) showing the highest rates. Although the reaction rates are low, the discovery of catalytic sites in copper-exchanged zeolites will accelerate the development of strategies to directly oxidize methane into methanol under mild conditions.

  10. 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)

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

    Directory of Open Access Journals (Sweden)

    Agnieszka Gubernat

    2017-01-01

    Full Text Available 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.

  12. Phases equilibria at low temperature between light hydrocarbons mixtures, methanol and water: measures and simulation

    Energy Technology Data Exchange (ETDEWEB)

    Rossilhol, N.

    1995-12-01

    In this work we discuss phase equilibria of mixtures similar to those formed during natural gas treatment (transportation and purification). The mixtures can contain light hydrocarbons (methane, ethane, propane, etc), acid gases (hydrogen sulfide, carbon dioxide), methanol (solvent, inhibitor) and (water). We present a low temperature phase equilibrium equipment to obtain two and three phase equilibrium data of light hydrocarbon-methanol-water mixtures. The realisation of the equipment, the measuring procedure and some determination of binary, ternary and quaternary systems are described. The range of application is - 100 deg. C to 0 deg. C in temperature and between 0 and 100 bar in pressure. The binary subsystems of the systems mentioned above are calculated in order to study the possibilities of the MHV2 and Wong and Sandler methods to represent simultaneously their vapor-liquid and liquid-liquid equilibria. According to the formalism proposed by the two methods, the cubic Soave-Redlich-Kwong equation of state is systematically combined with the NRTL excess Gibbs energy model. (authors). 72 refs., 47 figs., 38 tabs.

  13. Single step low temperature synthesis of gadolinium gallium garnet nanopowders

    Institute of Scientific and Technical Information of China (English)

    Rekha Mann; Kiranmala Laishram; Neelam Malhan

    2012-01-01

    Solution combustion synthesis of single-phase gadolinium gallium oxide (Gd3Ga5O12,GGG) nanopowders,by a fuel mixture approach using urea and glycine at a low temperature of 500 ℃,was being reported for the first time.Based on the fact that urea and glycine are good fuels for gallium oxide and gadolinium oxide synthesis,the fuel mixture composition was obtained,which could lead to direct phase pure cubic Gd3Ga5O12 formation without any subsequent calcination step.Combustion was carried out in furnace pre-heated at 500 ℃.Thermogravimetric analysis (TGA) of combustion product showed negligible mass loss indicating direct formation of GGG powder.Fourier transform infrared (FTIR) spectrum of combusted product showed peak characteristic of GGG in case of mixed fuel.X-ray diffraction (XRD) confirmed formation of phase pure GGG at 500 ℃ in preheated furnace.Very fine,well dispersed nanometric particles of size range of 50-100 nm were obtained,being uniform and close to spherical morphology as observed by transmission electron microscope (TEM).

  14. Low-temperature synthesis of nano-TiO{sub 2} anatase on nafion membrane for using on DMFC

    Energy Technology Data Exchange (ETDEWEB)

    Nguyen Manh Tuan; Nguyen Hoang Tuyen [Ho Chi Minh City Institute of Physics, Vietnam Academy of Science and Technology (VAST), 01 Mac Dinh Chi Street, 1 District, Ho Chi Minh City (Viet Nam); Ngo Thanh Nha [Can Tho University, Can Tho (Viet Nam)], E-mail: manhtuan2k@yahoo.com

    2009-09-01

    Low-temperature synthesis of 60-70 deg. C of anatase nanocrystalline titanium dioxide TiO{sub 2} using sol-gel technique on Nafion membrane is investigated and characterized. Titan tetraisopropoxide (TTIP) is used as precursor and ethanol as the solvent. The best precursor to solvent weight ratio has been used for the synthesis of nano-TiO{sub 2} particles. The X-ray diffractograms and TEM images show the formation of anatase structure of nanocrystalline TiO{sub 2} at low temperatures as shown with average particle size below 12 nm. The films deposited by spin coating technique using these nanoparticles show the crystalline and porous nature of the films. The nano-TiO{sub 2} film as shown can be used to reduce the cross-over permeation of methanol through the PEM and increase electric power of the DMFC.

  15. Synthesis of silicon carbide ceramics at low temperatures

    Energy Technology Data Exchange (ETDEWEB)

    McMillan, S.M.; Brook, R.J. [Univ. of Oxford (United Kingdom)

    1995-09-01

    This paper reports observations of the direct transformation of a polymeric precursor into amorphous Si-C, and crystalline SiC at low temperatures, and the use of this precursor as a binder for the productin of SiC composites.

  16. Synthesis of hydrocarbon fluid inclusions at low temperature

    Energy Technology Data Exchange (ETDEWEB)

    Pironon, J. (Centre de Recherche sur la Geologie de l' Uranium and GS-CNRS CREGU, Vandoeuvre-les-Nancy (France))

    Hydrocarbon fluid inclusions have been synthesized in halogenide and sulfate crystals at low temperature (<100C) and atmospheric pressure. Water-immiscible hydrocarbon droplets were either trapped separately or with an aqueous and/or a vapor phase. Impurities on the crystal surface were verified by infrared microspectrometry, and the similarity between the initial liquid and the liquid trapped in the inclusion was documented by Raman microspectrometry for nonfluorescent compounds. This inclusion type represents a new tool for understanding inclusion-formation phenomena and for the calibration of techniques used in hydrocarbon fluid-inclusion analysis ({mu}FT-IR, {mu}Raman, {mu}UV-fluorescence, gas chromatography, mass spectrometry); these inclusions allow one to obtain microthermometric calibration curves with a high precision at low temperature.

  17. Low-temperature synthesis of ZnO nanonails

    Science.gov (United States)

    Song, Xubo; Zhang, Yaohua; Zheng, Jie; Li, Xingguo

    2007-09-01

    Wurtzite ZnO nanonails on silicon substrate were successfully synthesized by thermal vapor transport and condensation method at a low temperature without a metal catalyst. Pure Zn powders were used as raw material and O2/Ar powders as source gas. The products were characterized by scanning electron microscopy, transmission electron microscopy and X-ray diffraction. The results show that the deposited nanostructures include aligned ZnO nanonails. The ZnO nanonails, with crystalline cap and small-diameter shafts, grow along the c-axis. The optical properties have been revealed by photoluminescence spectra. We considered that the ZnO nanonails growth is a vapor solid process.

  18. Low temperature solid-state synthesis of nanocrystalline gallium nitride

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Liangbiao, E-mail: wlb6641@163.com [Hefei National Laboratory for Physical Science at Microscale and Department of Chemistry, University of Science and Technology of China, Hefei, Anhui 230026 (China); Shi, Liang; Li, Qianwen; Si, Lulu; Zhu, Yongchun; Qian, Yitai [Hefei National Laboratory for Physical Science at Microscale and Department of Chemistry, University of Science and Technology of China, Hefei, Anhui 230026 (China)

    2012-11-15

    Graphical abstract: Display Omitted Highlights: ► GaN nanocrystalline was prepared via a solid-state reacion at relatively low temperature. ► The sizes and crystallinities of the GaN samples obtained at the different temperatures are investigated. ► The GaN sample has oxidation resistance and good thermal stability below 1000 °C. -- Abstract: Nanocrystalline gallium nitride was synthesized by a solid-state reaction of metallic magnesium powder, gallium sesquioxide and sodium amide in a stainless steel autoclave at a relatively low temperature (400–550 °C). The structures and morphologies of the obtained products were derived from X-ray powder diffraction (XRD) and transmission electron microscopy (TEM). XRD patterns indicated that the products were hexagonal GaN (JCPDS card no. 76-0703). The influence of reaction temperature on size of the products was studied by XRD and TEM. Furthermore, the thermal stability and oxidation resistance of the nanocrystalline GaN were also investigated. It had good thermal stability and oxidation resistance below 800 °C in air.

  19. Room and low temperature synthesis of carbon nanofibres

    CERN Document Server

    Boskovic, B 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 suit...

  20. Development of molecular and solid catalysts for the direct low-temperature oxidation of methane to methanol.

    Science.gov (United States)

    Palkovits, Regina; von Malotki, Christian; Baumgarten, Martin; Müllen, Klaus; Baltes, Christian; Antonietti, Markus; Kuhn, Pierre; Weber, Jens; Thomas, Arne; Schüth, Ferdi

    2010-02-22

    The direct low-temperature oxidation of methane to methanol is demonstrated on a highly active homogeneous molecular catalyst system and on heterogeneous molecular catalysts based on polymeric materials possessing ligand motifs within the material structure. The N-(2-methylpropyl)-4,5-diazacarbazolyl-dichloro-platinum(II) complex reaches significantly higher activity compared to the well-known Periana system and allows first conclusions on electronic and structural requirements for high catalytic activity in this reaction. Interestingly, comparable activities could be achieved utilizing a platinum modified poly(benzimidazole) material, which demonstrates for the first time a solid catalyst with superior activity compared to the Periana system. Although the material shows platinum leaching, improved activity and altered electronic properties, compared to the conventional Periana system, support the proposed conclusions on structure-activity relationships. In comparison, platinum modified triazine-based catalysts show lower catalytic activity, but rather stable platinum coordination even after several catalytic cycles. Based on these systems, further development of improved solid catalysts for the direct low-temperature oxidation of methane to methanol is feasible.

  1. 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.

  2. Method for the rapid synthesis of large quantities of metal oxide nanowires at low temperatures

    Energy Technology Data Exchange (ETDEWEB)

    Sunkara, Mahendra Kumar (Louisville, KY); Vaddiraju, Sreeram (Mountain View, CA); Mozetic, Miran (Ljubljan, SI); Cvelbar, Uros (Idrija, SI)

    2009-09-22

    A process for the rapid synthesis of metal oxide nanoparticles at low temperatures and methods which facilitate the fabrication of long metal oxide nanowires. The method is based on treatment of metals with oxygen plasma. Using oxygen plasma at low temperatures allows for rapid growth unlike other synthesis methods where nanomaterials take a long time to grow. Density of neutral oxygen atoms in plasma is a controlling factor for the yield of nanowires. The oxygen atom density window differs for different materials. By selecting the optimal oxygen atom density for various materials the yield can be maximized for nanowire synthesis of the metal.

  3. Low temperature synthesis of SiCN nanostructures

    Institute of Scientific and Technical Information of China (English)

    2009-01-01

    Silicon carbon nitride (SiCN) nanowires, nanorods and nanotubes have gained much attention due to their excellent field emission and photoluminescence properties. These nanostructures were usually grown using catalysts at high temperature (800―1000℃). In this paper, synthesis of SiCN nanostruc-tures at a temperature less than 500℃ is reported. Various kinds of SiCN nanostructures were synthe-sized using microwave plasma chemical vapor deposition method. Gas mixtures of CH4, H2 and N2 were used as precursors and Si chips were inserted in the sample holder at symmetrical positions around the specimen as additional Si sources. Metallic gallium was used as the liquid medium in a mechanism similar to vapor-liquid-solid. Morphologies of the resultant were characterized by field emission scan-ning electron microscopy. Energy dispersive spectrometry and X-ray photoelectron spectroscopy were used to characterize their compositions and bonding states.

  4. Low temperature synthesis of SiCN nanostructures

    Institute of Scientific and Technical Information of China (English)

    CHENG Wen Juan; MA XueMing

    2009-01-01

    Silicon carbon nitride (SiCN) nanowires, nanorods and nanotubes have gained much attention due to their excellent field emission and photoluminescence properties. These nanostructures were usually grown using catalysts at high temperature (800-1000℃). In this paper, synthesis of SiCN nanostruc-tures at a temperature less than 500℃ is reported. Various kinds of SiCN nanostructures were synthe-sized using microwave plasma chemical vapor deposition method. Gas mixtures of CH4, H2 and N2 were used as precursors and Si chips were inserted in the sample holder at symmetrical positions around the specimen as additional Si sources. Metallic gallium was used as the liquid medium in a mechanism similar to vapor-liquid-solid. Morphologies of the resultant were characterized by field emission scan-ning electron microscopy. Energy dispersive spectrometry and X-ray photoelectron spectroscopy were used to characterize their compositions and bonding states.

  5. Non-syngas direct steam reforming of methanol to hydrogen and carbon dioxide at low temperature.

    Science.gov (United States)

    Yu, Kai Man Kerry; Tong, Weiyi; West, Adam; Cheung, Kevin; Li, Tong; Smith, George; Guo, Yanglong; Tsang, Shik Chi Edman

    2012-01-01

    A non-syngas direct steam reforming route is investigated for the conversion of methanol to hydrogen and carbon dioxide over a CuZnGaO(x) catalyst at 150-200 °C. This route is in marked contrast with the conventional complex route involving steam reformation to syngas (CO/H2) at high temperature, followed by water gas shift and CO cleanup stages for hydrogen production. Here we report that high quality hydrogen and carbon dioxide can be produced in a single-step reaction over the catalyst, with no detectable CO (below detection limit of 1 ppm). This can be used to supply proton exchange membrane fuel cells for mobile applications without invoking any CO shift and cleanup stages. The working catalyst contains, on average, 3-4 nm copper particles, alongside extremely small size of copper clusters stabilized on a defective ZnGa2O4 spinel oxide surface, providing hydrogen productivity of 393.6 ml g(-1)-cat h(-1) at 150 °C.

  6. Low-temperature, template-free synthesis of single-crystal bismuth telluride nanorods

    Energy Technology Data Exchange (ETDEWEB)

    Purkayastha, A. [Department of Materials Science and Engineering, Rensselaer Polytechnic Institute, 110 Eighth Street, Troy, NY 12180 (United States); Lupo, F. [Max Planck Institut fuer Metallforschung, Heisenbergstrasse 3, D-70569 Stuttgart (Germany); Kim, S.; Borca-Tasciuc, T. [Department of Mechanical, Aerospace, and Nuclear Engineering, Rensselaer Polytechnic Institute, 110 Eighth Street, Troy, NY 12180 (United States); Ramanath, G. [Department of Materials Science and Engineering, Rensselaer Polytechnic Institute, 110 Eighth Street, Troy, NY 12180 (United States); Max Planck Institut fuer Festkoerperforschung, Heisenbergstrasse 1, D-70569 Stuttgart (Germany)

    2006-02-17

    Synthesis of single-crystal bismuth telluride nanorods is reported by using a low-temperature, template-free approach. Films of thioglycolic acid functionalized nanorods doped with sulfur exhibit n-type behavior with a high Seebeck coefficient, holding promise for thermoelectric device applications. (Abstract Copyright [2006], Wiley Periodicals, Inc.)

  7. Functional conservation analysis and expression modes of grape anthocyanin synthesis genes responsive to low temperature stress.

    Science.gov (United States)

    Zhang, Cheng; Jia, Haifeng; Wu, Weimin; Wang, Xicheng; Fang, Jinggui; Wang, Chen

    2015-12-10

    In grape cultivation, low temperature generally increases the expression of genes involved in synthesis of anthocyanin. In this study, multi-type structural analysis of the proteins encoded by five anthocyanin biosynthesis genes VvF3H, VvPAL, VvCHS3, VvCHS2 and VvLDOX, in addition to nine of their homologous genes revealed that proteins in grapevine shared a high similarity with that in kiwi, red orange and some other species in which the biosynthesis of anthocyanin significantly influenced by low temperature as proved by previous studies. Low temperature regulatory elements were also found in the promoter region of the grapevine genes VvCHS2, VvPAL and VvF3H. These findings indicate that the functions of anthocyanin biosynthesis genes in grapevine are conservative and might be sensitive to low temperature. In order to identify the specific expression patterns of the five anthocyanin biosynthesis genes and the changes of polyphenols, anthocyanins and flavonoids under low temperature stress. The transcription analysis of the five genes and the content of polyphenols, anthocyanins and flavonoids in grape skins were examined, by using Vitis vinifera L. cv. 'Yongyou 1' and 'Juxing' berries as experimental material and treated at 4°C and 25°C for 24h, 48 h, 72 h and 96 h. The results showed that low temperature greatly enhanced the expression of the five anthocyanin biosynthesis genes. Low temperature greatly slowed down the decomposition of polyphenol, anthocyanin, and flavonoid in grape skins. Our study also found that cv. 'Juxing' responded more sensitively to low temperature than cv. 'Yongyou 1'. All the findings would provide a basis for further study on the mechanism of anthocyanin biosynthesis under environmental stress.

  8. Advances in nanoscale alloys and intermetallics: low temperature solution chemistry synthesis and application in catalysis.

    Science.gov (United States)

    Jana, Subhra

    2015-11-21

    Based on the bottom-up chemistry techniques, the size, shape, and composition controlled synthesis of nanoparticles can now be achieved uniformly, which is of great importance to the nanoscience community as well as in modern catalysis research. The low-temperature solution-phase synthesis approach represents one of the most attractive strategies and has been utilized to synthesize nanoscale metals, alloys and intermetallics, including a number of new metastable phases. This perspective will highlight the solution-based nanoparticle synthesis techniques, a low-temperature platform, for the synthesis of size and shape-tunable nanoscale transition metals, alloys, and intermetallics from the literature, keeping a focus on the utility of these nanomaterials in understanding the catalysis. For each solution-based nanoparticle synthesis technique, a comprehensive overview has been given for the reported nanoscale metals, alloys, and intermetallics, followed by critical comments. Finally, their enhanced catalytic activity and durability as novel catalysts have been discussed towards several hydrogenation/dehydrogenation reactions and also for different inorganic to organic reactions. Hence, the captivating advantages of this controllable low-temperature solution chemistry approach have several important implications and together with them this approach provides a promising route to the development of next-generation nanostructured metals, alloys, and intermetallics since they possess fascinating properties as well as outstanding catalytic activity.

  9. Low Temperature One-Step Synthesis of Barium Titanate:Thermodynamic Modeling and Experimental Synthesis

    Institute of Scientific and Technical Information of China (English)

    沈志刚; 李世刚; 刘朝文; 张建文; 陈建峰

    2005-01-01

    A thermodynamic model has been developed to determine the reaction conditions favoring low temperature direct synthesis of barium titanate (BaTiO3). The method utilizes standard-state thermodynamic data for solid and aqueous species and a Debye-Hǔckel coefficients model to represent solution nonideality. The method has been used to generate phase stability diagrams that indicate the ranges of pH and reagent concentrations, for which various species predominate in the system at a given temperature. Also, yield diagrams have been constructed that indicate the concentration, pH and temperature conditions for which different yields of crystalline BaTiO3 can be obtained. The stability and yield diagrams have been used to predict the optimum synthesis conditions (e.g.,reagent concentrations, pH and temperature). Subsequently, these predictions have been experimentally verified.As a result, phase-pure perovskite BaTiO3 has been obtained at temperature ranging from 55 to 85℃ using BaCl2,TiCl4 as a source for Ba and Ti. and NaOH as a orecioitator.

  10. Combustion synthesis and structural analysis of nanocrystalline nickel ferrite at low temperature regime

    Energy Technology Data Exchange (ETDEWEB)

    Shanmugavel, T., E-mail: gokulrajs@hotmail.com, E-mail: shanmugavelnano@gmail.com [Department of Physics, Anna University of Technology, Coimbatore-641 047 (India); Raj, S. Gokul, E-mail: gokulrajs@hotmail.com, E-mail: shanmugavelnano@gmail.com [Department of Physics, Vel tech University, Avadi, Chennai-600062 India (India); Rajarajan, G. [Department of Physics, Selvam College of Technology, Namakkal-637005 India (India); Kumar, G. Ramesh [Department of Physics, University College of Engineering, Anna University Chennai, Arni 632317 (India); Boopathi, G. [Department of Physics, Presidency College (Autonomous), Chennai - 600005 (India)

    2015-06-24

    Combustion synthesis of single phase Nickel ferrite was successfully achieved at low temperature regime. The obtained powders were calcinated to increase the crystallinity and their characterization change due to calcinations is investigated in detail. Citric acid used as a chelating agent for the synthesis of nickel ferrite. Pure single phase nickel ferrites were found at this low temperature. The average crystalline sizes were measured by using powder XRD measurements. Surface morphology was investigated through Transmission Electron Microscope (TEM). Particle size calculated in XRD is compared with TEM results. Magnetic behaviour of the samples is analyzed by using Vibrating Sample Magnetometer (VSM). Saturation magnetization, coercivity and retentivity are measured and their results are discussed in detail.

  11. Low Temperature Synthesis of Rutile TiO2 Nanocrystals and Their Photovoltaic and Photocatalytic Properties.

    Science.gov (United States)

    Roy, Subhasis; Han, Gill Sang; Shin, Hyunjung; Lee, Jin Wook; Mun, Jinsoo; Shin, Hyunho; Jung, Hyun Suk

    2015-06-01

    We report a novel method of synthesizing rutile TiO2 nanocrystals at low temperature (200 degrees C) via a butanol rinsing process followed by heat treatment in an O2 atmosphere. The rutile nanocrystals show uniform size distribution of approximately 20 nm and good crystallinity confirmed by X-ray diffraction and transmission electron microscopy. A mechanism for the low temperature synthesis of rutile nanocrystals is rationalized in terms of an explosive thermal decomposition reaction of butoxy groups on TiO2 powders with O2 gas. Characterizations of the photovoltaic and photocatalytic properties of rutile nanocrystals exhibited higher photoactivity than large-sized conventional rutile powder, which demonstrates that this novel synthesis technology could expand applications of rutile powders to various photoactive devices beyond solar cells and photocatalysts.

  12. 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.

  13. 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.

  14. A review of nanostructured lithium ion battery materials via low temperature synthesis.

    Science.gov (United States)

    Chen, Jiajun

    2013-01-01

    Nanostructured materials afford us new opportunities to improve the current technology for synthesizing Li ion batteries. Generating nanomaterials with new properties via an inexpensive approach offers a tremendous potential for realizing high performance Li-ion batteries. In this review, I mainly summarize some of the recent progress made, and describe the patents awarded on synthesizing nanostructured cathode materials for these batteries via low temperature wet- chemistry methods. From an economical view, such syntheses, especially hydrothermal synthesis, may offer the opportunities for significantly lowering the cost of manufacturing battery materials, while conferring distinct environmental advantages. Recent advances in in-situ (real time) X-ray diffraction for studying hydrothermal synthesis have great potential for bettering the rational design of advanced lithium-electrode materials. The development of this technique also will be discussed.

  15. Synthesis of nanocrystalline yttrium iron garnet by low temperature solid state reaction

    Energy Technology Data Exchange (ETDEWEB)

    Yu Hongtao, E-mail: yuhongtao@swust.edu.cn; Zeng Liwen; Lu Chao; Zhang Wenbo; Xu Guangliang

    2011-04-15

    In this work, nanocrystalline yttrium iron garnet powders were produced by low temperature solid state reaction. The phase evolution during the procedure was determined from the thermogravimetric and differential thermal analysis, and the x-ray diffraction patterns. The results of transmission electron microscopy indicated that the prepared powders exhibited grain size at the nano-level of 20 {approx} 40 nm. Dense ceramics with a theoretical density of around 98% were obtained from the prepared powders after sintering at 1280 deg. C, a relative low sintering temperature compared with conventional ceramic processes, and the saturation magnetizations of sintered samples were also determined. - Research Highlights: {yields}No sol or gel form during the synthesis processing using nitrates and citric acid as raw materials. {yields}The synthesis method needs a low heating temperature (700 deg. C) compared with conventional solid state reaction. {yields}The product is a single phase with homogeneous size distribution and nano grains (20 {approx} 40 nm) confirmed by TEM. {yields}Dense YIG ceramic can be sintered at a low temperature (1280 deg. C) compared with that in conventional processing.

  16. 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.

  17. Low-temperature synthesis of LiFePO4 nanocrystals by solvothermal route.

    Science.gov (United States)

    Lim, Jinsub; Kang, Sung-Won; Moon, Jieh; Kim, Sungjin; Park, Hyosun; Baboo, Joseph Paul; Kim, Jaekook

    2012-01-05

    LiFePO4 nanocrystals were synthesized at a very low temperature of 170°C using carbon nanoparticles by a solvothermal process in a polyol medium, namely diethylene glycol without any heat treatment as a post procedure. The powder X-ray diffraction pattern of the LiFePO4 was indexed well to a pure orthorhombic system of olivine structure (space group: Pnma) with no undesirable impurities. The LiFePO4 nanocrystals synthesized at low temperature exhibited mono-dispersed and carbon-mixed plate-type LiFePO4 nanoparticles with average length, width, and thickness of approximately 100 to 300 nm, 100 to 200 nm, and 50 nm, respectively. It also appeared to reveal considerably enhanced electrochemical properties when compared to those of pristine LiFePO4. These observed results clearly indicate the effect of carbon in improving the reactivity and synthesis of LiFePO4 nanoparticles at a significantly lower temperature.

  18. Boron nitride nanowalls: low-temperature plasma-enhanced chemical vapor deposition synthesis and optical properties

    Science.gov (United States)

    Merenkov, Ivan S.; Kosinova, Marina L.; Maximovskii, Eugene A.

    2017-05-01

    Hexagonal boron nitride (h-BN) nanowalls (BNNWs) were synthesized by plasma-enhanced chemical vapor deposition (PECVD) from a borazine (B3N3H6) and ammonia (NH3) gas mixture at a low temperature range of 400 °C-600 °C on GaAs(100) substrates. The effect of the synthesis temperature on the structure and surface morphology of h-BN films was investigated. The length and thickness of the h-BN nanowalls were in the ranges of 50-200 nm and 15-30 nm, respectively. Transmission electron microscope images showed the obtained BNNWs were composed of layered non-equiaxed h-BN nanocrystallites 5-10 nm in size. The parallel-aligned h-BN layers as an interfacial layer were observed between the film and GaAs(100) substrate. BNNWs demonstrate strong blue light emission, high transparency (>90%) both in visible and infrared spectral regions and are promising for optical applications. The present results enable a convenient growth of BNNWs at low temperatures.

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

    Energy Technology Data Exchange (ETDEWEB)

    Dhand, Vivek [Department of Mechanical Engineering, College of Engineering, Kyung Hee University, 446–701 Yongin (Korea, Republic of); Rhee, K.Y., E-mail: rheeky@khu.ac.kr [Department of Mechanical Engineering, College of Engineering, Kyung Hee University, 446–701 Yongin (Korea, Republic of); Park, Soo-Jin, E-mail: sjpark@inha.ac.kr [Department of Chemistry, Inha University, Incheon (Korea, Republic of)

    2014-03-01

    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.

  20. Low-temperature synthesis of zeolite from perlite waste — Part II: characteristics of the products

    Science.gov (United States)

    Król, Magdalena; Morawska, Justyna; Mozgawa, Włodzimierz; Pichór, Waldemar

    2014-12-01

    The paper investigates the properties of sodium zeolites synthesized using the hydrothermal method under autogenous pressure at low temperature with NaOH solutions of varying concentrations. During this modification, zeolites X, Na-P1 and hydroxysodalite were synthesized. The synthesis parameters, and thus, phase composition of resulting samples, significantly affected the specific surface area (SSA) and cation exchange capacity (CEC). SSA increased from 2.9 m2/g to a maximum of 501.2 m2/g, while CEC rose from 16 meq/100 g to a maximum of 500 meq/100 g. The best properties for use as a sorbent were obtained for perlite waste modified with 4.0 M NaOH at 70 °C or 80 °C.

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

    Science.gov (United States)

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

    2014-03-01

    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.

  2. Process analysis and mechanism investigation of low temperature synthesis of nanoscale calcium hexaboride powder.

    Science.gov (United States)

    Zhang, Lin; Feng, Gang; Min, Guanghui

    2014-10-01

    The synthesis of nanoscale CaB6 powder via the low temperature chemical reaction of Calcium chloride (CaCl2) with Sodium Borohyride (NaBH4) in vacuum has been investigated in this study. The reaction temperature was determined by differential scanning calorimetry and thermogravimetric analysis (DSC and TG). Crystallization process was provided through studying the influence of heat preservation time on the crystal particles morphologies in vacuum. X-ray diffraction (XRD) was used to investigate the phase and structure of CaB6. The characterization for microstructure was performed by transmission electron microscopy (TEM) and high resolution transmission electron microscopy (HRTEM). The elemental analysis was conducted by X-ray photoelectron spectroscopy (XPS). It is concluded that CaB6 nanoparticles can be successfully prepared under low temperature at 500 degrees C. The results showed that in vacuum, 2 hours heat preservation time is enough for the reaction to complete at this temperature. The average size of crystal grains is 25.1 nm with high crystallinity and cubic shaped, which particles size is at the range of 20-100 nm. Longer heat preservation time more than 2 hours will make CaB6 particles connected together to form hard aggregations, that is the sintering process occurred under this temperature. However, the crystal grain size changed unobviously accompanying the holding time prolong due to the high chemical stability of CaB6. The atomic ratio of B to Ca is 5.37:1, less than but close to its stoichiometric ratio 6:1. The synthesis process and mechanism were investigated in this paper.

  3. Synthesis of magnetic nanostructures: Shape tuning by the addition of a polymer at low temperature

    Energy Technology Data Exchange (ETDEWEB)

    Rashid, Md. Harunar; Raula, Manoj; Mandal, Tarun K., E-mail: psutkm@iacs.res.in

    2014-06-01

    We report a simple method for shape-controlled synthesis of iron oxide spinels such as magnetite (Fe{sub 3}O{sub 4}) and maghemite (γ-Fe{sub 2}O{sub 3}) nanostructures using a thermoresponsive polymer poly(vinyl methyl ether) (PVME) by the alkaline hydrolysis of iron salt at low temperature (20 °C). Microscopic analysis confirmed the formation of needle- and flower-shaped iron oxide nanostructures depending on reaction conditions. High-resolution transmission electron microscopic analysis of the needle- and flower-shaped nanostructures as well as their corresponding selected area electron diffraction patterns revealed that the formed nanostructures are crystalline in nature. X-ray diffraction study reveals the formation of well-crystalline pure Fe{sub 3}O{sub 4} and γ-Fe{sub 2}O{sub 3} nanostructures under different reaction conditions. Fourier transform Infra-red spectroscopic analysis confirms the adsorption of PVME on the surface of iron oxide nanostructures. Finally, the magnetic properties of γ-Fe{sub 2}O{sub 3} and Fe{sub 3}O{sub 4} nanostructures is studied that shows the superparamagnetic behavior of the formed iron oxide nanostructures. - Graphical abstract: A simple method for shape-controlled synthesis of iron oxide spinels such as magnetite (Fe{sub 3}O{sub 4}) and maghemite (γ-Fe{sub 2}O{sub 3}) nanostructures using a thermoresponsive polymer poly(vinyl methyl ether) (PVME) by the alkaline hydrolysis of iron salt at low temperature (20 °C) is described. Display Omitted - Highlights: • Low-temperature method for iron oxide (Fe{sub 3}O{sub 4} and γ-Fe{sub 2}O{sub 3}) nanostructures is described. • Shape of iron oxide nanostructures can be tuned by varying the reaction parameter. • Needle- and flower-shaped iron oxide nanostructures are obtained with polymer. • HRTEM analysis shows iron oxide nanostructures are crystalline in nature. • Both γ-Fe{sub 2}O{sub 3} and Fe{sub 3}O{sub 4} nanostructures shows superparamagnetic behavior.

  4. Technical Superiority and Applicative Progress for Low Temperature Methanol Wash Process%低温甲醇洗工艺的技术优势及应用进展

    Institute of Scientific and Technical Information of China (English)

    汪家铭

    2013-01-01

    Low temperature methanol wash technology was a kind of gas purification method,in which the acid gases of CO2, H2S, COS etc.were re-moved by using of cold methanol as a solvent.Author has introduced the technical superiority of Linde Company's and Lurgi Company's Rectisol process, has commented the newest application situation of Rectisol technogy in field of large-sized coal-made methanol, coal-made synthesis ammonia, coal-made natural gas etc.%低温甲醇洗技术是利用冷甲醇作为溶剂,脱除CO2、H2 S、COS等酸性气体的一种气体净化方法。介绍了德国Linde公司和Lurgi公司低温甲醇洗工艺的技术优势;评述了低温甲醇洗技术在大型煤制甲醇、煤制合成氨、煤制天然气等煤化工领域的最新应用情况。

  5. Simple mass production of zinc oxide nanostructures via low-temperature hydrothermal synthesis

    Science.gov (United States)

    Ghasaban, Samaneh; Atai, Mohammad; Imani, Mohammad

    2017-03-01

    The specific properties of zinc oxide (ZnO) nanoparticles have attracted much attention within the scientific community as a useful material for biomedical applications. Hydrothermal synthesis is known as a useful method to produce nanostructures with certain particle size and morphology however, scaling up the reaction is still a challenging task. In this research, large scale hydrothermal synthesis of ZnO nanostructures (60 g) was performed in a 5 l stainless steel autoclave by reaction between anionic (ammonia or sodium hydroxide) and cationic (zinc acetate dehydrate) precursors in low temperature. Hydrothermal reaction temperature and time were decreased to 115 °C and 2 or 6 h. In batch repetitions, the same morphologies (plate- and needle-like) with reproducible particle size were obtained. The nanostructures formed were analyzed by powder x-ray diffraction, Fourier-transform infrared spectroscopy, energy dispersive x-ray analysis, scanning electron microscopy and BET analysis. The nanostructures formed were antibacterially active against Staphylococcus aureus.

  6. Ethylene glycol assisted low-temperature synthesis of boron carbide powder from borate citrate precursors

    Directory of Open Access Journals (Sweden)

    Rafi-ud-din

    2014-09-01

    Full Text Available B4C powders were synthesized by carbothermal reduction of ethylene glycol (EG added borate citrate precursors, and effects of EG additions (0–50 mol% based on citric acid on the morphologies and yields of synthesized B4C powders were investigated. The conditions most suitable for the preparation of precursor were optimized and optimum temperature for precursor formation was 650 °C. EG additions facilitated low-temperature synthesis of B4C at 1350 °C, which was around 100–300 °C lower temperature compared to that without EG additions. The lowering of synthesis temperature was ascribed to the enlargement of interfacial area caused by superior homogeneity and dispersibility of precursors enabling the diffusion of reacting species facile. The 20% EG addition was optimal with free residual carbon lowered to 4%. For smaller EG additions, the polyhedral and rod-like particles of synthesized product co-existed. With higher EG additions, the morphology of synthesized product was transformed into needle and blade-like structure.

  7. Low-temperature Magnesiothermic Synthesis of Mesoporous Silicon Carbide from an MCM-48/Polyacrylamide Nanocomposite Precursor

    Institute of Scientific and Technical Information of China (English)

    Zahra Saeedifar; Amir Abbas Nourbakhsh; Roozbeh Javad Kalbasi; Ebrahim Karamian

    2013-01-01

    Mesoporous silicon carbide with high specific surface area was successfully synthesized from an MCM-48/polyacrylamide nanocomposite precursor in the temperature range of 550-600 ℃ (below the melting point of Mg) by means of a magnesiothermic reduction process.The MCM-48/polyacrylamide precursor nanocomposite was prepared by in-situ polymerization of acrylamide monomer in the presence of mesoporous MCM-48 synthesized by sol-gel method.The physicochemical properties and microstructures of the nanocomposite precursor and the low-temperature SiC product were characterized by X-ray diffraction (XRD),differential scanning calorimetry-thermo gravimetric analysis (DSC-TGA),transmission electron microscopy (TEM) and N2 adsorption-desorption.TEM micrographs and Brunauer-Emmett-Teller (BET) gas adsorption studies showed that the SiC powder was nanocrystalline and had a specific surface area of 330 m2/g and a mesoporosity in the range of 2-10 nm.The presence of an exothermic peak in the DSC trace corresponds to the self-combustion process of the SiC magnesiothermic synthesis.The results also show that the carbon in excess to that required to produce SiC plays a role in the reduction of the SiO2.The mechanism of magnesiothermic synthesis of mesoporous SiC is discussed.

  8. Low temperature route for the synthesis of rare earth transition metal borides and their hydrides

    Energy Technology Data Exchange (ETDEWEB)

    Kramp, S.; Febri, M.; Joubert, J.C. [CNRS UMR 5628, Saint Martin d`Heres (France)

    1997-10-01

    Synthesis of rare earth-based alloys by the ORD technique consists in the reduction of rare earth oxides in a melt of calcium under argon, and simultaneous diffusion-reaction of the just formed rare earth metal with the other elements. This method has been applied with success to numerous ternary borides containing transition metals such as the magnetic alloys Y{sub 2}Co{sub 14}B, LnCo{sub 4}B, and YCo{sub 3}B{sub 2}. By using a small excess of Ca, boride particles grow in a viscous slurry media containing unreacted (melted) Ca and nanosize CaO particles. Single phase boride alloys can be obtained at 1000{degrees}C as loose micrometer-size particles of very high crystal quality as confirmed by the sharp diffraction peaks on the corresponding X-ray diagrams. Particles can be easily recovered by gentle wishing in diluted weak acid solution, and dried under vacuum at room temperature. This rather low temperature technique is particularly adapted to the synthesis of incongruent melting phases, as well as for the alloys containing volatile rare earth elements (Sm, Yb, Tb,...).

  9. A Low Temperature Route for the Synthesis of Rare Earth Transition Metal Borides and Their Hydrides

    Science.gov (United States)

    Kramp, S.; Febri, M.; Joubert, J. C.

    1997-10-01

    Synthesis of rare earth-based alloys by the ORD technique consists in the reduction of rare earth oxides in a melt of calcium under argon, and simultaneous diffusion-reaction of the just formed rare earth metal with the other elements. This method has been applied with success to numerous ternary borides containing transition metals such as the magnetic alloys Y2Co14B, LnCo4B, and YCo3B2. By using a small excess of Ca, boride particles grow in a viscous slurry media containing unreacted (melted) Ca and nanosize CaO particles. Single phase boride alloys can be obtained at 1000°C as loose micrometer-size particles of very high crystal quality as confirmed by the sharp diffraction peaks on the corresponding X-ray diagrams. Particles can be easily recovered by gentle washing in diluted weak acid solution, and dried under vacuum at room temperature. This rather low temperature technique is particularly adapted to the synthesis of incongruent melting phases, as well as for the alloys containing volatile rare earth elements (Sm, Yb, Tb,…).

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

    Science.gov (United States)

    Kumar, Avshish; Khan, Sunny; Zulfequar, M.; Harsh; Husain, Mushahid

    2017-04-01

    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.

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

    Science.gov (United States)

    Bhavani, P.; Rajababu, C. H.; Arif, M. D.; Reddy, I. Venkata Subba; Reddy, N. Ramamanohar

    2017-03-01

    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 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 (MS) of 103.017 emu/g and low remanant magnetization (Mr) of 0.22 emu/g with coercivity (Hc) of 70.9 Oe, which may be attributed to the smaller magnetic domains (dm) and dead magnetic layer thickness (t).

  12. 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.

  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. Novel efficient process for methanol synthesis by CO2 hydrogenation

    NARCIS (Netherlands)

    Kiss, Anton A.; Pragt, J.J.; Vos, H.J.; Bargeman, G.; Groot, de 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 o

  15. Selective oxidation of CO on Ru/{gamma}-Al{sub 2}O{sub 3} in methanol reformate at low temperatures

    Energy Technology Data Exchange (ETDEWEB)

    Han, Y.-F.; Kinne, M.; Behm, R.J. [Abt. Oberflachenchemie und Katalyse, Universitat Ulm, D-89069 Ulm (Germany)

    2004-09-15

    The preferential oxidation of CO (PROX) at low temperatures, 80-120C, over a Ru/{gamma}-Al{sub 2}O{sub 3} supported catalyst pretreated by a low temperature reduction (LTR) process was investigated over a range of CO partial pressures and O{sub 2} excess in a realistic methanol reformate reaction environment, in the presence of CO{sub 2} and H{sub 2}O. Based on transmission electron microscopy (TEM) imaging the LTR pretreatment, which involves reduction in pure H{sub 2} at 150C, does not lead to measurable particle growth (d{sub Ru}=2.5nm), in contrast to the calcination/reduction (CR) pretreatment at 350C used previously, which results in considerable particle sintering (d{sub Ru}=11.2nm).Kinetic parameters including the apparent activation energy (E{approx}48kJ/mol), reaction orders for CO ({alpha}{sub CO}) and for O{sub 2} ({alpha}{sub O{sub 2}2}) and the selectivity for CO oxidation as well as the influence of the co-reactants CO{sub 2} and H{sub 2}O were evaluated. The results show a significant activity and selectivities of around 55-60% both in idealized reformate, in the absence of CO{sub 2} and H{sub 2}O, and in realistic reformate, already at 80C. This and the negligible activity for the reverse water gas shift and the CO and CO{sub 2} methanation reaction under these reaction conditions make this catalyst suitable for application at low temperatures typical for operation of polymer electrolyte fuel cells (PEFCs), in contrast to the CR pretreated catalyst, where higher process temperatures are required.

  16. Methanol synthesis using a catalyst combination of alkali or alkaline earth salts and reduced copper chromite for methanol synthesis

    Science.gov (United States)

    Tierney, John W.; Wender, Irving; Palekar, Vishwesh M.

    1993-01-01

    The present invention relates to a novel route for the synthesis of methanol, and more specifically to the production of methanol by contacting synthesis gas under relatively mild conditions in a slurry phase with a catalyst combination comprising reduced copper chromite and basic alkali salts or alkaline earth salts. The present invention allows the synthesis of methanol to occur in the temperature range of approximately 100.degree.-160.degree. C. and the pressure range of 40-65 atm. The process produces methanol with up to 90% syngas conversion per pass and up to 95% methanol selectivity. The only major by-product is a small amount of easily separated methyl formate. Very small amounts of water, carbon dioxide and dimethyl ether are also produced. The present catalyst combination also is capable of tolerating fluctuations in the H.sub.2 /CO ratio without major deleterious effect on the reaction rate. Furthermore, carbon dioxide and water are also tolerated without substantial catalyst deactivation.

  17. Crystal size growth in the liquid phase methanol synthesis catalyst

    Energy Technology Data Exchange (ETDEWEB)

    Sawant, A.; Lee, S.; Foos, A.

    1988-01-01

    The phenomenon of crystal growth in the methanol synthesis catalyst has been studied. Crystallite size distributions in the CuO/ZnO/Al/sub 2/O/sub 3/ methanol synthesis catalyst have been determined. The effects of temperature, reaction environment and time under reaction conditions have been studied. It is observed that water in the reaction mixture promotes crystal growth. 26 refs., 10 figs., 1 tab.

  18. Application of methanol synthesis reactor to large-scale plants

    Institute of Scientific and Technical Information of China (English)

    LOU Ren; XU Rong-liang; LOU Shou-lin

    2006-01-01

    The developing status of world large-scale methanol production technology is analyzed and Linda's JW low-pressure methanol synthesis reactor with uniform temperature is described. JW serial reactors have been successfully introduced in and applied in Harbin Gasification Plant and the productivity has been increased by 50% and now nine sets of equipments are successfully running in Harbin Gasification Plant,Jiangsu Xinya, Shandong Kenli,Henan Zhongyuan, Handan Xinyangguang,' Shanxi Weihua and Inner Mongolia Tianye. Now it has manufacturing the reactors of 300,000 t/a for Liaoning Dahua. Some solutions for the structure problems of 1000 ~5000 t/d methanol synthesis rectors are put forward.

  19. Hydrothermal synthesis of hydrocarbons at low temperature. Implications for sustaining a biosphere in Europa

    Science.gov (United States)

    Navarro-Gonzalez, Rafael; Montoya, Lilia; Davis, Wanda; McKay, Chris

    Observational evidence from Earth-borne systems and space missions as well as theoretical arguments suggest that Jupiter's satellite Europa could be geologically active today and may possess an ocean of liquid water of about 100 km deep underneath the icy surface about 10 km thickness. The existence of an aqueous ocean is an important requirement for life, as we know it. However, a biosphere also depends of an adequate energy source to drive the most fundamental biological processes such as metabolism, growth, reproduction, etc. Methanogenesis associated with hydrothermal vents may potentially drive a biosphere in an European ocean. We report here on the production of a large variety of hydrocarbons in hydrothermal systems at low temperatures (150° C). The chemical composition of the hydrothermal vent gases was derived from a thermochemical model that assumes that Europa had a cometary (solar, less H) abundance at high temperatures characteristic of a vent. Specifically the following gas mixture was used: 45% CO2 , 45% CH4, and 10 % N2 . A 500 ml stainless steel reactor was filled with 200 ml triply distilled water and the gas mixture at 1 bar at 25° C. In some experiments 3 g of pyrite were added into the reaction vessel. The system was heated for 24 hrs in the temperature range from 100 to 375° C. At the completion of the experiment, the reaction was quenched to 25° C and the gas mixture was analyzed by GC-FTIR-MS techniques. In the absence of pyrite, methane is oxidized to carbon dioxide with the possible production of hydrogen. In contrast in the presence of pyrite, methane is converted into a suite of hydrocarbons from C2 to C7 containing all possible isomers. The production of these compounds was found at temperatures as low as 150° C. In order to get a better understanding of the chemical mechanism involved in the synthesis of hydrocarbons and explore the effect on the initial oxidation state of the carbon used, we performed additional experiments in

  20. Characterization of Pr-CeO2 Nano-crystallites Prepared by Low-temperature Combustion & Hydrothermal Synthesis

    Institute of Scientific and Technical Information of China (English)

    ZHU Zhen-Feng; WANG Bao-Li; MA Jian-Zhong

    2006-01-01

    Pr-CeO2 Nano-crystalline red pigments were prepared by low-temperature combustion with a later hydrothermal treatment using Ce(NO3)3·6H2O and Pr6O11 as raw materials. The phase composition, coloring mechanism and morphology of pigments were analyzed by XRD, SEM,EDS and XPS. Results showed that Pr-CeO2 solid solution with a fluorite structure was obtained by the diffusion of Pr+3 into CeO2 crystal lattice during the synthesis process. XPS analysis indicated that Pr+3 substitutes Ce+4 in CeO2 and is compensated by oxygen vacancies. Compared with low-temperature combustion synthesis, the Pr-CeO2 pigments prepared with a subsequent hydrothermal treatment have an average grain size of about 16.70 nm, and the crystallinity and red tonality are improved.

  1. 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

  2. Efficient green methanol synthesis from glycerol

    Science.gov (United States)

    Haider, Muhammad H.; Dummer, Nicholas F.; Knight, David W.; Jenkins, Robert L.; Howard, Mark; Moulijn, Jacob; Taylor, Stuart H.; Hutchings, Graham J.

    2015-12-01

    The production of biodiesel from the transesterification of plant-derived triglycerides with methanol has been commercialized extensively. Impure glycerol is obtained as a by-product at roughly one-tenth the mass of the biodiesel. Utilization of this crude glycerol is important in improving the viability of the overall process. Here we show that crude glycerol can be reacted with water over very simple basic or redox oxide catalysts to produce methanol in high yields, together with other useful chemicals, in a one-step low-pressure process. Our discovery opens up the possibility of recycling the crude glycerol produced during biodiesel manufacture. Furthermore, we show that molecules containing at least two hydroxyl groups can be converted into methanol, which demonstrates some aspects of the generality of this new chemistry.

  3. Synthesis and Optimization of a Methanol Process

    DEFF Research Database (Denmark)

    Grue, J.; Bendtsen, Jan Dimon

    2003-01-01

    In the present paper, a simulation model for a methanol process is proposed. The objective is to develop a model for flowsheet optimization, which requires simple thermodynamic and unit operation models. Simplified thermodynamic models are combined with a more advanced model for the rate of react......In the present paper, a simulation model for a methanol process is proposed. The objective is to develop a model for flowsheet optimization, which requires simple thermodynamic and unit operation models. Simplified thermodynamic models are combined with a more advanced model for the rate...

  4. 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.

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

    OpenAIRE

    Zhang Liu; Zicong Jian; Jianzhang Fang; Xiaoxin Xu; Ximiao Zhu; Shuxing Wu

    2012-01-01

    Nanocrystalline titanium dioxide ( T i O 2 ) 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 sur...

  6. 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  |

  7. Low-Temperature Synthesis of Bismuth Chalcohalides: Candidate Photovoltaic Materials with Easily, Continuously Controllable Band gap

    Science.gov (United States)

    Kunioku, Hironobu; Higashi, Masanobu; Abe, Ryu

    2016-09-01

    Although bismuth chalcohalides, such as BiSI and BiSeI, have been recently attracting considerable attention as photovoltaic materials, the methods available to synthesize them are quite limited thus far. In this study, a novel, facile method to synthesize these chalcohalides, including BiSBr1-xIx solid solutions, at low temperatures was developed via the substitution of anions from O2- to S2- (or Se2-) using bismuth oxyhalide precursors. Complete phase transition was readily observed upon treatment of BiOI particles with H2S or H2Se at surprisingly low temperatures of less than 150 °C and short reaction times of less than 1 h, producing BiSI and BiSeI particles, respectively. This method was also applied for synthesizing BiSBr1-xIx, where continuous changes in their band gaps were observed depending on the ratio between iodine and bromine. The composition of all elements (except oxygen) in the chalcohalides thus produced was almost identical to that of the oxyhalide precursors, attributed to the suppressed volatilization of halogens at such low temperatures. All chalcohalides loaded on FTO clearly exhibited an anodic photocurrent in an acetonitrile solution containing I-, attributed to their n-type nature, e.g., the BiSI electrode exhibited high IPCE (64% at 700 nm, +0.2 V vs. Ag/AgCl).

  8. Synthesis and Optimization of a Methanol Proces

    DEFF Research Database (Denmark)

    Grue, J.; Bendtsen, Jan Dimon

    2003-01-01

    In the present paper, a simulation model for a methanol process is proposed. The objective is to develop a model for flowsheet optimization, which requires simple thermodynamic and unit operation models. Simplified thermodynamic models are combined with a more advanced model for the rate of react...

  9. 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.

  10. 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.

  11. The Equilibrium Compositions of Methanol Synthesis System by Cornstalk Syngas

    Science.gov (United States)

    Zhu, Ling-feng; Zhao, Qing-ling; Wang, Yang-yang; Chen, Jing; Zhang, Le; Zhang, Run-tao; Liu, Li-li; Zhang, Zhao-yue

    2010-11-01

    Methanol can be used as a promising alternative for conventional gasoline and Diesel fuel. It is necessary to decompose biomass such as cornstalks in order to produce methanol which is a raw material from agricultural residues. A promising route for processing cornstalks is firstly to gasify cornstalks with thermo-chemical method to prepare the syngas, which can be conducted under a down-flow fixed bed gasifier. The low-heat-value cornstalk syngas produced in this way needs purification and a variety of technical procedures such as deoxygenation, desulfurization, catalytic cracking of tar and hydrogenation. In this paper, the catalytic experiments of methanol synthesis with cornstalk syngas were carried out in a tubular-flow integral and isothermal reactor. The effect such as reaction temperature, pressure, catalyst types, catalyst particle size, syngas flow at entering end and composition of syngas was investigated. Moreover, the equilibrium constants (Kf1, Kf2, KP1, KP2), equilibrium compositions and the concentrations of each part of the equilibrium system for methanol synthesis were calculated by SHBWR state equation under given reaction pressure. The results provided basic data for the design of the industrial equipments in which catalyzed synthesis of methanol from cornstalk gases is operated.

  12. Optimization of synthesis of upconversion luminescence material NaYF4:Er3+,Yb3+ nanometer-phosphor by low-temperature combustion synthesis method

    Institute of Scientific and Technical Information of China (English)

    LU Liping; ZHANG Xiyan

    2013-01-01

    A kind of Er3+-yb3+ co-doped natrium yttrium fluoride nanometer-phosphor sensitive to 980 nm was synthesized by the low-temperature combustion synthesis method,which expanded the application range of the low-temperature combustion synthesis (LCS) method which is always used in the synthesis of oxides and compound oxides.The synthesis conditions were optimized with orthogonal experiments and the optimum technological parameters were obtaincd.Intense upconversion emissions at 522,540 and 653 nm corresponding to the 2H11/2,4S3/2,and 4F9/2 transitions to the 4I15/2 ground state were observed when excited by continuous wavclength (CW) laser radiation at 980 nm.The effect of the carbamide amount on the phase formation and the luminescence intensity was analyzed.The average particle size of the sample was 30-40 nm.

  13. Thermal stability analysis of the liquid phase methanol synthesis reactor

    Energy Technology Data Exchange (ETDEWEB)

    Gogate, M.R.; Desirazu, S.; Berty, J.M.; Lee, S. (Akron University, Akron, OH (USA). Dept. of Chemical Engineering)

    1992-01-01

    The effect of addition of an inert liquid phase on the rate of heat generation in the catalytic synthesis of methanol from syngas has been studied. Gas compositions typical of product gases from Lurgi and Koppers-Totzek gasifiers, represented by H[sub 2]-rich and CO-rich syngas respectively, were used to experimentally verify the 'slope' and 'dynamic' criteria in a three-phase fixed bed recycle reactor. The liquid medium, Witco-40 oil, has been effective in controlling the rate of heat generation and in preventing catalyst overheating, signifying that the liquid phase synthesis is thermally far more stable than the vapour phase synthesis. The experimental thermal stability study provides crucial and valuable information in commercializing the liquid phase methanol synthesis process. The current approach of thermal stability analysis does not require any a priori assumption or predetermined reaction kinetics. 22 refs., 6 figs., 7 tabs.

  14. 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.

  15. Low-temperature plasma synthesis of carbon nanotubes and graphene based materials and their fuel cell applications.

    Science.gov (United States)

    Wang, Qi; Wang, Xiangke; Chai, Zhifang; Hu, Wenping

    2013-12-07

    Carbon nanotubes (CNTs) and graphene, and materials based on these, are largely used in multidisciplinary fields. Many techniques have been put forward to synthesize them. Among all kinds of approaches, the low-temperature plasma approach is widely used due to its numerous advantages, such as highly distributed active species, reduced energy requirements, enhanced catalyst activation, shortened operation time and decreased environmental pollution. This tutorial review focuses on the recent development of plasma synthesis of CNTs and graphene based materials and their electrochemical application in fuel cells.

  16. Preparation of conductive film via a low temperature synthesis that enables simultaneous nitrogen doping and reduction of graphene oxide

    Science.gov (United States)

    Bhattacharyya, Tamoghna

    2017-08-01

    A low temperature (‒78 °C), one-pot synthesis that enables the simultaneous reduction of graphene oxide (G-O) and nitrogen doping of reduced graphene oxide (rG-O) is described. The method facilitates the effective removal of oxygen-containing functional groups in the G-O and introduces both ‘graphitic’ and ‘pyridinic’ nitrogen up to 4% in the corresponding product. The N-doped materials displayed relatively high powder electrical conductivities (up to 2.5  ×  103 S m-1).

  17. Synthesis and optical enhancement of amorphous carbon nanotubes/silver nanohybrids via chemical route at low temperature.

    Science.gov (United States)

    Han, Tan Kim; Fen, Leo Bey; Nee, Ng Meng; Johan, Mohd Rafie

    2014-01-01

    We report the synthesis of amorphous carbon nanotubes/silver (αCNTs/Ag) nanohybrids via simple chemical route without additional reactant and surfactant at low temperature. Field emission scanning microscope (FESEM) and transmission electron microscope (TEM) confirmed formation of CNTs. X-ray diffraction (XRD) pattern confirmed the amorphous phase of carbon and the formation of Ag nanoparticles crystalline phase. Raman spectra revealed the amorphous nature of α CNTs. UV-visible spectroscopy showed enhancement of optical properties of α CNTs/Ag nanohybrids.

  18. Low temperature synthesis of ordered mesoporous stable anatase nanocrystals: the phosphorus dendrimer approach.

    Science.gov (United States)

    Brahmi, Younes; Katir, Nadia; Ianchuk, Mykhailo; Collière, Vincent; Essassi, El Mokhtar; Ouali, Armelle; Caminade, Anne-Marie; Bousmina, Mosto; Majoral, Jean Pierre; El Kadib, Abdelkrim

    2013-04-07

    The scarcity of low temperature syntheses of anatase nanocrystals prompted us to explore the use of surface-reactive fourth generation phosphorus-dendrimers as molds to control the nucleation and growth of titanium-oxo-species during the sol-gel mineralization process. Unexpectedly, the dendritic medium provides at low temperature, discrete anatase nanocrystals (4.8 to 5.2 nm in size), in marked contrast to the routinely obtained amorphous titanium dioxide phase under standard conditions. Upon thermal treatment, heteroatom migration from the branches to the nanoparticle surface and the ring opening polymerization of the cyclophosphazene core provide stable, interpenetrating mesoporous polyphosphazene-anatase hybrid materials (-P[double bond, length as m-dash]N-)n-TiO2. The steric hindrance of the dendritic skeleton, the passivation of the anatase surface by heteroatoms and the ring opening of the core limit the crystal growth of anatase to 7.4 nm and prevent, up to 800 °C, the commonly observed anatase-to-rutile phase transformation. Performing this mineralization in the presence of similar surface-reactive but non-dendritic skeletons (referred to as branch-mimicking dendrimers) failed to generate crystalline anatase and to efficiently limit the crystal growth, bringing thus clear evidence of the virtues of phosphorus dendrimers in the design of novel nanostructured materials.

  19. 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 fro...

  20. High-Energy-Low-Temperature Technologies for the Synthesis of Nanoparticles: Microwaves and High Pressure

    Directory of Open Access Journals (Sweden)

    Witold Lojkowski

    2014-11-01

    Full Text Available Microwave Solvothermal Synthesis (MSS is a chemical technology, where apart from possible effects of microwaves on the chemical reaction paths, microwave heating allows the precise planning of a time-temperature schedule, as well as to achieve high super-saturation of the reagents uniformly in the reactor vessel. Thus, MSS is suitable for production of nanoparticles with small grain size distribution and a high degree of crystallinity. A further advantage of the technology is a much lower synthesis temperature than for gas phase, plasma or sol-gel technologies. New reactors have been developed to exploit these advantages of the MSS technology of nanoparticles synthesis and to scale up the production rate. Reactor design and realization has been shown to be decisive and critical for the control of the MSS technology. Examples of oxidic and phosphatic nanoparticles synthesis have been reported.

  1. Large-Scale Synthesis of Silver Nanoparticles by Aqueous Reduction for Low-Temperature Sintering Bonding

    Directory of Open Access Journals (Sweden)

    Qiu Xiliang

    2014-01-01

    Full Text Available Silver nanoparticles with average diameter of 22.4 nm were prepared by aqueous reduction method for low-temperature sintering bonding application. The reaction temperature and PVP concentration, which are the influential factors of nanoparticle characteristics, were investigated during reduction process. In our research, monodispersity of nanoparticles was remarkably improved while unfavorable agglomeration was avoided with the AgNO3/PVP mass ratio of 1 : 4 at the reaction temperature 30°C. Besides, copper pads were successfully bonded using sintering paste employing fresh silver nanoparticles with diameter of 20~35 nm at 200°C. In addition, after morphology of the bonding joint was analysed by scanning electron microscope (SEM, the porous sintering characteristics were confirmed.

  2. Low-temperature synthesis of water-dispersible anatase titanium dioxide nanoparticles for photocatalysis.

    Science.gov (United States)

    Jing, Jieying; Feng, Jie; Li, Wenying; Yu, William W

    2013-04-15

    Water-dispersible anatase TiO2 nanoparticles were synthesized at a low temperature (80°C) without using surfactants via the mechanism of electrostatic stabilization. The water-dispersible TiO2 nanoparticles solution was stable and no precipitation occurred after 3months. Photocatalytic evaluation demonstrated that the as-synthesized TiO2 nanoparticles possess excellent quinoline degradation performance (a 2.33×10(-2)min(-1) apparent reaction rate constant comparing to 1.22×10(-2)min(-1) for P25) and recycle stability (the photocatalytic activity remained 96.6% of the initial activity after four cycles of repetitive uses). These could be attributed to the small size and good water-dispersibility of the as-synthesized TiO2 nanoparticles that led to large specific surface area and easy photogenerated electron-hole transportation.

  3. Synthesis and Characterization of MnZn Ferrite at Low Temperature

    Directory of Open Access Journals (Sweden)

    ZHAO Hai-tao

    2016-11-01

    Full Text Available Pure phase spinel ferrite nanoparticles (Mn0.5Zn0.5Fe2O4 were one-step synthesized by the sol-gel auto-combustion method at low temperature. The structural characteristics, morphology and thermal decomposition were characterized by X-ray Diffraction (XRD, Scanning Electron Microscope (SEM, TG-DSC analyzer, respectively. The results indicate that pure phase Mn0.5Zn0.5Fe2O4 ferrite nanoparticles of about 60nm in diameter can be directly synthesized after auto-combustion of the nitrate-citrate xerogel under the conditions of pH=7.0, R=1:1 and C(CA=0.7 mol/L. The obtained nanoparticles show the diameter increases and the diffraction peak narrows but the strength increases after calcined at 400℃ which improves the crystal structure.

  4. Synthesis of hexagonal monocrystal AlN microtubes and nanowires at low temperature

    Institute of Scientific and Technical Information of China (English)

    Lv Hui-Min; Chen Guang-De; Yan Guo-Jun; Ye Hong-Gang

    2007-01-01

    This paper reports that pure hexagonal aluminium nitride microtubes and nanowires growing along the [0001] direction have been successfully synthesized by directly reacting AlCl3 with NaN3 at low temperature (450℃) under condition of non-solvent system. The grey-white powder of reacting product was characterized by high-resolution transmission electron microscope (HRTEM), which shows that the powder is long straight-wire morphology with outer diameter from 40 nm to 300 nm and length up to several micrometres. The results of both electron diffraction (ED)and x-ray diffraction (XRD) indicate that the AlN microtubes have a pure hexagonal monocrystal tubular structure with the combination of the curled AlN nanobelts. Room-temperature photoluminescence spectrum of the synthesized sample showed an emission peak, which is closely related to the small size of the microtubes.

  5. 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.

  6. Organometallic Synthesis of CuO Nanoparticles: Application in Low-Temperature CO Detection.

    Science.gov (United States)

    Jońca, Justyna; Ryzhikov, Andrey; Palussière, Ségolène; Esvan, Jérome; Fajerwerg, Katia; Menini, Philippe; Kahn, Myrtil L; Fau, Pierre

    2017-08-24

    A metal-organic approach has been employed for the preparation of anisotropic CuO nanoparticles. These nanostructures have been characterized by transmission and high resolution transmission electron microscopy, field-emission scanning electron microscopy, X-ray powder diffraction, Fourier transform infrared spectroscopy and X-ray photoelectron spectroscopy. The CuO nanoparticles have been deposited as gas-sensitive layers on miniaturized silicon devices. At an operating temperature of 210 °C, the sensors present an optimum response toward carbon monoxide correlated with a fast response (Rn) and short recovery time. A high sensitivity to CO (Rn≈150 %, 100 ppm CO, RH 50 %) is achieved. These CuO nanoparticles serve as a very promising sensing layer for the fabrication of selective CO gas sensors working at a low temperature. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  7. 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.

  8. Synthesis of ZnO eggshell-like hollow spheres via thermal evaporation at low temperature

    Energy Technology Data Exchange (ETDEWEB)

    Xu, L L; Zhao, P Q; Wu, X L; Xiong, X; Huang, G S; Chen, H T; Zhu, J [National Laboratory of Solid State Microstructures and Department of Physics, Nanjing University, Nanjing 210093 (China)

    2007-08-07

    Hollow zinc oxide microspheres have been successfully synthesized on silicon substrate via simple thermal evaporation of pure zinc powder without any catalyst or template material at a relatively low temperature of 550 deg. C. The morphologies, chemical composition and crystal structure are characterized using x-ray powder diffraction, transmission electron microscopy and scanning electron microscopy. A smooth surface and rough ones with many nanopores are observed. The difference in the structures of the shells is discussed and a possible growth mechanism is proposed in detail. The room-temperature photoluminescence spectrum reveals a peak at 380 nm corresponding to free exciton emission and a strong green emission at {approx} 525 nm associated with defect-related emission.

  9. Activity of Catalyst for Liquid Phase Methanol Synthesis

    Institute of Scientific and Technical Information of China (English)

    WANGYuefa; JanezLevec

    2002-01-01

    The effects of reduction procedure, reaction temperature and composition of feed gas on the activity of a CuO-ZnO-Al2O3 catalyst for liquid phase methanol synthesis were studied. An optimized procedure different from conventional ones was developed to obtain higher activity and better stability of the catalyst. Both CO and CO2 in the feed gas were found to be necessary to maintain the activity of catalyst in the synthesis process. Reaction temperature was limited up to 523K, otherwise the catalyst will be deactivated rapidly. Experimental results show that the catalyst deactivation is caused by sintering and fouling, and the effects of CO and CO2 on the catalyst activity are also investigated. The experimental results indicate that the formation of water in the methanol synthesis is negligible when the feed gas contains both CO and CO2. The mechanism for liquid-phase methanol synthesis was discussed and it differed slightly from that for gas-phase synthesis.

  10. 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.

  11. Simultaneous production of methanol and dimethylether from synthesis gas

    OpenAIRE

    Akarmazyan, Siranush

    2015-01-01

    Dimethylether is a non-toxic liquefied gas, which is projected to become one of the fundamental chemical feedstock in the future. Dimethylether can be produced from syngas via a two-step (indirect) process that involves synthesis of methanol by hydrogenation of CO/CO2 over a copper based catalyst and subsequent dehydration of methanol to DME over an acidic catalyst. Alternatively, DME can be produced in an one-step (direct) process using a hybrid (bifunctional) catalyst system that permits bo...

  12. Synthesis of MgB2 at Low Temperature and Autogenous Pressure

    Directory of Open Access Journals (Sweden)

    Ian D. R. Mackinnon

    2014-05-01

    Full Text Available High quality, micron-sized interpenetrating grains of MgB2, with high density, are produced at low temperatures (~420 °C < T < ~500 °C under autogenous pressure by pre-mixing Mg powder and NaBH4 and heating in an Inconel 601 alloy reactor for 5–15 h. Optimum production of MgB2, with yields greater than 75%, occurs for autogenous pressure in the range 1.0 MPa to 2.0 MPa, with the reactor at ~500 °C. Autogenous pressure is induced by the decomposition of NaBH4 in the presence of Mg and/or other Mg-based compounds. The morphology, transition temperature and magnetic properties of MgB2 are dependent on the heating regime. Significant improvement in physical properties accrues when the reactor temperature is held at 250 °C for >20 min prior to a hold at 500 °C.

  13. 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.

  14. Template-assisted low temperature synthesis of functionalized graphene for ultrahigh volumetric performance supercapacitors.

    Science.gov (United States)

    Yan, Jun; Wang, Qian; Wei, Tong; Jiang, Lili; Zhang, Milin; Jing, Xiaoyan; Fan, Zhuangjun

    2014-05-27

    We demonstrated the fabrication of functionalized graphene nanosheets via low temperature (300 °C) treatment of graphite oxide with a slow heating rate using Mg(OH)2 nanosheets as template. Because of its dented sheet with high surface area, a certain amount of oxygen-containing groups, and low pore volume, the as-obtained graphene delivers both ultrahigh specific gravimetric and volumetric capacitances of 456 F g(-1) and 470 F cm(-3), almost 3.7 times and 3.3 times higher than hydrazine reduced graphene, respectively. Especially, the obtained volumetric capacitance is the highest value so far reported for carbon materials in aqueous electrolytes. More importantly, the assembled supercapacitor exhibits an ultrahigh volumetric energy density of 27.2 Wh L(-1), which is among the highest values for carbon materials in aqueous electrolytes, as well as excellent cycling stability with 134% of its initial capacitance after 10,000 cycles. Therefore, the present work holds a great promise for future design and large-scale production of high performance graphene electrodes for portable energy storage devices.

  15. Low temperature hydrothermal synthesis of octahedral Fe{sub 3}O{sub 4} microcrystals

    Energy Technology Data Exchange (ETDEWEB)

    Zhang Wei; Gai Ligang; Li Zhili; Jiang Haihui; Ma Wanyong [School of Chemical Engineering, Shandong Institute of Light Industry, Jinan 250353 (China)], E-mail: liganggai@yahoo.com

    2008-11-21

    Octahedral Fe{sub 3}O{sub 4} crystals in the size range of 200-300 nm have been prepared with a high yield at a low temperature of 90 deg. C using a simple polyethylene glycol (PEG)-mediated hydrothermal approach. It is found that both PEG molecules and NaOH content are crucial for the formation of Fe{sub 3}O{sub 4} octahedrons because of the selective adsorption of PEG molecules on the (1 1 1) planes of Fe{sub 3}O{sub 4} at higher NaOH concentrations, delaying the crystal growth along the [1 1 1] axis. The formation mechanisms related to Fe{sub 3}O{sub 4} nuclei, octahedral crystals, and their linear self-assembly structures are discussed. Magnetization measurements show that the Fe{sub 3}O{sub 4} octahedrons have a relatively high magnetic saturation value of 85.5 emu g{sup -1} and a coercive field of 118 Oe, which is ascribed to the high crystalline perfection and chain-like structures of the sample.

  16. Low temperature synthesis of iron containing carbon nanoparticles in critical carbon dioxide

    Science.gov (United States)

    Hasumura, Takashi; Fukuda, Takahiro; Whitby, Raymond L. D.; Aschenbrenner, Ortrud; Maekawa, Toru

    2011-01-01

    We develop a low temperature, organic solvent-free method of producing iron containing carbon (Fe@C) nanoparticles. We show that Fe@C nanoparticles are self-assembled by mixing ferrocene with sub-critical (25.0 °C), near-critical (31.0 °C) and super-critical (41.0 °C) carbon dioxide and irradiating the solutions with UV laser of 266-nm wavelength. The diameter of the iron particles varies from 1 to 100 nm, whereas that of Fe@C particles ranges from 200 nm to 1 μm. Bamboo-shaped structures are also formed by iron particles and carbon layers. There is no appreciable effect of the temperature on the quantity and diameter distributions of the particles produced. The Fe@C nanoparticles show soft ferromagnetic characteristics. Iron particles are crystallised, composed of bcc and fcc lattice structures, and the carbon shells are graphitised after irradiation of electron beams.

  17. 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.

  18. Low-temperature synthesis of silicon carbide inert matrix fuel through a polymer precursor route

    Energy Technology Data Exchange (ETDEWEB)

    Shih, Chunghao [Department of Materials Science and Engineering, University of Florida, Gainesville, FL 32611 (United States); Tulenko, James S. [Department of Nuclear and Radiological Engineering, University of Florida, Gainesville, FL 32611 (United States); Baney, Ronald H., E-mail: rbane@mse.ufl.edu [Department of Materials Science and Engineering, University of Florida, Gainesville, FL 32611 (United States)

    2011-02-28

    A low temperature process of mixing different sizes of silicon carbide (SiC) particles with a polymer precursor was utilized to synthesize SiC pellets for potential use as inert matrix fuels (IMF) for light water reactors. The lower temperature process is required to prevent the reactions between SiC and the dispersed PuO{sub 2} fuel material. The effect of the polymer content and the cold pressing pressure on the packing of SiC particles was investigated. The effect of mixing coarse and fine SiC particles on the density and the pore size distribution was also investigated. It was found that the density and pore size distribution can be tailored by controlling the SiC size compositions, polymer content and pressing pressure at room temperature. A possible mechanism has been proposed to explain the forming of the pores with respect to the geometric arrangement between SiC particles and the polymer precursor. SEM images showed that ceria (cerium oxide) which is a PuO{sub 2} surrogate in this study, was well distributed in the pellet.

  19. Low-temperature synthesis of silicon carbide inert matrix fuel through a polymer precursor route

    Science.gov (United States)

    Shih, Chunghao; Tulenko, James S.; Baney, Ronald H.

    2011-02-01

    A low temperature process of mixing different sizes of silicon carbide (SiC) particles with a polymer precursor was utilized to synthesize SiC pellets for potential use as inert matrix fuels (IMF) for light water reactors. The lower temperature process is required to prevent the reactions between SiC and the dispersed PuO 2 fuel material. The effect of the polymer content and the cold pressing pressure on the packing of SiC particles was investigated. The effect of mixing coarse and fine SiC particles on the density and the pore size distribution was also investigated. It was found that the density and pore size distribution can be tailored by controlling the SiC size compositions, polymer content and pressing pressure at room temperature. A possible mechanism has been proposed to explain the forming of the pores with respect to the geometric arrangement between SiC particles and the polymer precursor. SEM images showed that ceria (cerium oxide) which is a PuO 2 surrogate in this study, was well distributed in the pellet.

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

    Energy Technology Data Exchange (ETDEWEB)

    Feng, Li-Wei; Chang, Chun-Yen [Department of Electronics Engineering and Institute of Electronics, National Chiao Tung University, Hsinchu, 300, Taiwan (China); Chang, Ting-Chang, E-mail: tcchang@mail.phys.nsysu.edu.tw [Department of Physics, National Sun Yat-Sen University, Kaohsiung, 804, Taiwan (China); Center for Nanoscience and Nanotechnology, National Sun Yat-Sen University, Kaohsiung, 804, Taiwan (China); Tu, Chun-Hao; Wang, Pai-Syuan [Department of Electronics Engineering and Institute of Electronics, National Chiao Tung University, Hsinchu, 300, Taiwan (China); Lin, Chao-Cheng [Green Energy and Environment Research Laboratories, Industrial Technology Research Institute, Hsinchu, 310, Taiwan (China); Chen, Min-Chen [Department of Physics, National Sun Yat-Sen University, Kaohsiung, 804, Taiwan (China); Huang, Hui-Chun; Gan, Der-Shin; Ho, New-Jin [Institute of Materials Science and Engineering, National Sun Yat-Sen University, Kaohsiung, 804, Taiwan (China); Chen, Shih-Ching [Department of Physics, National Sun Yat-Sen University, Kaohsiung, 804, Taiwan (China); Chen, Shih-Cheng [Department of Electrical Engineering and Institute of Electronic Engineering, National Tsing Hua University, Hsinchu, 310, Taiwan (China)

    2011-11-30

    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 Degree-Sign C, and separated well at 600 Degree-Sign C annealing. However, it was also observed that significant thermal desorption of Ge atoms occurs at 600 Degree-Sign 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 Degree-Sign C annealing. The electrical characteristics of data retention in the sample with the 600 Degree-Sign C annealing exhibited better performance than the 500 Degree-Sign C-annealed sample, a result associated with the better separation and better crystallization of the NC structures.

  1. Synthesis of Nitrogen-Doped Graphene Quantum Dots at Low Temperature for Electrochemical Sensing Trinitrotoluene.

    Science.gov (United States)

    Cai, Zhewei; Li, Fumin; Wu, Ping; Ji, Lijuan; Zhang, Hui; Cai, Chenxin; Gervasio, Dominic F

    2015-12-01

    Nitrogen-doped graphene quantum dots (N-GQDs) are synthesized at low temperature as a new catalyst allowing electrochemical detection of 2,4,6-trinitrotoluene (TNT). N-GQDs are made by an oxidative ultrasonication of graphene oxide (GO) forming nanometer-sized species, which are then chemically reduced and nitrogen doped by reacting with hydrazine. The as-synthesized N-GQDs have an average diameter of ∼2.5 nm with an N/C atomic ratio of up to ∼6.4%. To detect TNT, TNT is first accumulated on N-GQDs modified glassy carbon (N-GQDs/GC) electrode by holding the electrode at a 0 V versus Ag/AgCl for 150 s in an aqueous TNT solution. Next, the N-GQDs/GC electrode with accumulated TNT is transferred to a fresh PBS solution (0.1 M, pH 7.0, without TNT), where the TNT reduction current at -0.36 V versus Ag/AgCl in a linear scan voltammogram (LSV) shows a linear response to TNT concentration in the aqueous solution from 1 to 400 ppb, with a correlation coefficient of 0.999, a detection limit of 0.2 ppb at a signal/noise (S/N) of 3, and a detection sensitivity of 363 ± 7 mA mM(-1) cm(-2). The detection limit of 0.2 ppb of TNT for this new method is much lower than 2 ppb set by the U.S. Environmental Protection Agency for drinking water. Therefore, N-GQDs allow an electrochemical method for assaying TNT in drinking water to determine if levels of TNT are safe or not.

  2. Low temperature carbothermal and boron carbide reduction synthesis of LaB{sub 6}

    Energy Technology Data Exchange (ETDEWEB)

    Hasan, Muhammad; Sugo, Heber; Kisi, Erich, E-mail: Erich.Kisi@newcastle.edu.au

    2013-11-25

    Highlights: •Two simple solid-state synthesis routes to yield pure LaB{sub 6} between 1350-1450°C are reported. •The mechanism of LaB{sub 6} synthesis has been explained. •The mean crystallite size for both methods is below one micron suggesting good sinterability. •LaB{sub 6} manufactured by these procedures exhibits a Richardson work function of 2.64 eV. -- Abstract: Rare-earth hexaborides are widely used as thermionic emitters however their economic production for large scale applications such as solar thermionic electricity generation is hampered by a need to synthesise them at lower temperature without post-synthesis cleaning treatments. Two simple synthesis techniques for producing pure lanthanum hexaboride (LaB{sub 6}), carbothermal reduction using La{sub 2}O{sub 3}–boron–carbon and boron carbide reduction using La{sub 2}O{sub 3}–B{sub 4}C blends respectively were studied. Using fine grained starting materials and a mild pre-milling treatment, the carbothermal method was found to produce high-purity LaB{sub 6} at a temperature 1400 °C or below. The B{sub 4}C method also appeared from XRD and SEM analyses of abraded surfaces to produce high-purity LaB{sub 6} at 1400 °C however EDS maps of polished cross-sections revealed the presence of unreacted B{sub 4}C necessitating a temperature of 1450 °C to complete the reaction. XRD and SEM analyses indicate that the mean particle sizes of LaB{sub 6} using the boron carbide method (220 nm) is smaller than that for the carbothermal reduction method (600 nm). The finer grains of samples prepared via the boron carbide method result in a partially sintered powder. LaB{sub 6} prepared in this way is shown to have a Richardson work function of 2.64 eV.

  3. Low-Temperature Synthesis of Superconducting Nanocrystalline MgB2

    Directory of Open Access Journals (Sweden)

    Jun Lu

    2010-01-01

    Full Text Available Magnesium diboride (MgB2 is considered a promising material for practical application in superconducting devices, with a transition temperature near 40 K. In the present paper, nanocrystalline MgB2 with an average particle size of approximately 70 nm is synthesized by reacting LiBH4 with MgH2 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.

  4. 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.

  5. 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.

  6. Changes in Protein Synthesis in Rapeseed (Brassica napus) Seedlings during a Low Temperature Treatment 1

    Science.gov (United States)

    Meza-Basso, Luis; Alberdi, Miren; Raynal, Monique; Ferrero-Cadinanos, Maria-Luz; Delseny, Michel

    1986-01-01

    Changes induced by cold treatment in young rapeseed (Brassica napus) seedlings were investigated at the molecular level. Following germination at 18°C for 48 hours, one half of the seedlings was transferred to 0°C for another 48 hour period, the other half being kept at 18°C as a control. Newly synthesized proteins were labeled for the last 6 hours of incubation with [35S]methionine. The different polypeptides were separated by two-dimensional electrophoresis in polyacrylamide gels. Newly synthesized proteins were revealed by fluorography. Protein synthesis clearly continues at 0°C and some polypeptides preferentially accumulate at this temperature. On the other hand, synthesis of several others is repressed while many are insensitive to cold treatment. Similar changes are also observed when mRNA is prepared from cold treated seedlings, translated in vitro in a reticulocyte cell free system and compared with the products of mRNA extracted from control samples. Among the genes which are repressed we identified the small subunit of ribulose 1,6-bisphosphate carboxylase. These changes are also detectable after shorter treatments. Images Fig. 1 Fig. 2 Fig. 3 PMID:16665102

  7. 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.

  8. 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.)

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

    Science.gov (United States)

    Lupinetti, Anthony J.; Garcia, Eduardo; Abney, Kent D.

    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.

  10. Low-temperature synthesis of CuO-interlaced nanodiscs for lithium ion battery electrodes

    Directory of Open Access Journals (Sweden)

    Seo Seung-Deok

    2011-01-01

    Full Text Available Abstract In this study, we report the high-yield synthesis of 2-dimensional cupric oxide (CuO nanodiscs through dehydrogenation of 1-dimensional Cu(OH2 nanowires at 60°C. Most of the nanodiscs had a diameter of approximately 500 nm and a thickness of approximately 50 nm. After further prolonged reaction times, secondary irregular nanodiscs gradually grew vertically into regular nanodiscs. These CuO nanostructures were characterized using X-ray diffraction, transmission electron microscopy, and Brunauer-Emmett-Teller measurements. The possible growth mechanism of the interlaced disc CuO nanostructures is systematically discussed. The electrochemical performances of the CuO nanodisc electrodes were evaluated in detail using cyclic voltammetry and galvanostatic cycling. Furthermore, we demonstrate that the incorporation of multiwalled carbon nanotubes enables the enhanced reversible capacities and capacity retention of CuO nanodisc electrodes on cycling by offering more efficient electron transport paths.

  11. ZnO 1-D nanostructures: Low temperature synthesis and characterizations

    Indian Academy of Sciences (India)

    Apurba Dev; S Chaudhuri; B N Dev

    2008-06-01

    ZnO is one of the most important semiconductors having a wide variety of applications in photonic, field emission and sensing devices. In addition, it exhibits a wide variety of morphologies in the nano regime that can be grown by tuning the growth habit of the ZnO crystal. Among various nanostructures, oriented 1-D nanoforms are particularly important for applications such as UV laser, sensors, UV LED, field emission displays, piezoelectric nanogenerator etc. We have developed a soft chemical approach to fabricate well-aligned arrays of various 1-D nanoforms like nanonails, nanowires and nanorods. The microstructural and photoluminescence properties of all the structures were investigated and tuned by varying the synthesis parameters. Field emission study from the aligned nanorod arrays exhibited high current density and a low turn-on field. These arrays also exhibited very strong UV emission and week defect emission. These structures can be utilized to fabricate efficient UV LEDs.

  12. Synthesis and characterization of LiFePO4 cathode preparation by low temperature method

    Science.gov (United States)

    Rajesh, Desapogu; Srinivas Naik, V.; Sunandana, C. S.

    2015-05-01

    We review in detail the physics and technology of the novel material LiFePO4, a potential cathode material for Li-ion batteries. In the present work, nano crystalline LiFePO4 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 LiFePO4 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. Fe3+ impurity characterization has been done by using ESR.

  13. Single-molecule synthesis and characterization of metal-ligand complexes by low-temperature STM.

    Science.gov (United States)

    Liljeroth, Peter; Swart, Ingmar; Paavilainen, Sami; Repp, Jascha; Meyer, Gerhard

    2010-07-14

    We present scanning tunneling microscopy (STM)-based single-molecule synthesis of linear metal-ligand complexes starting from individual metal atoms (iron or nickel) and organic molecules (9,10-dicyanoanthracene) deposited on an ultrathin insulating film. We directly visualize the frontier molecular orbitals by STM orbital imaging, from which, in conjunction with detailed density functional theory calculations, the electronic structure of the complexes is inferred. Our studies show how the order of the molecular orbitals and the spin-state of the complex can be engineered through the choice of the metal atom. The high-spin iron complex has a singly occupied delocalized orbital with a large spin-splitting that points to the use of these engineered complexes as modular building blocks in molecular spintronics.

  14. Zeolite synthesis from paper sludge ash at low temperature (90 degrees C) with addition of diatomite.

    Science.gov (United States)

    Wajima, Takaaki; Haga, Mioko; Kuzawa, Keiko; Ishimoto, Hiroji; Tamada, Osamu; Ito, Kazuhiko; Nishiyama, Takashi; Downs, Robert T; Rakovan, John F

    2006-05-20

    Paper sludge ash was partially converted into zeolites by reaction with 3M NaOH solution at 90 degrees C for 24 h. The paper sludge ash had a low abundance of Si and significant Ca content, due to the presence of calcite that was used as a paper filler. Diatomite was added to the NaOH solution to increase its Si content in order to synthesize zeolites with high cation exchange capacity. Diatomite residue was filtered from solution before addition of ash. The original ash without addition of diatomite yielded hydroxysodalite with a cation exchange capacity ca. 50 cmol/kg. Addition of Si to the solution yielded Na-P1 (zeolite-P) with a higher cation exchange capacity (ca. 130 cmol/kg). The observed concentrations of Si and Al in the solution during the reaction explain the crystallization of these two phases. The reaction products were tested for their capacity for PO(4)(3-) removal from solution as a function of Ca(2+) content, suggesting the formation of an insoluble Ca-phosphate salt. The product with Na-P1 exhibits the ability to remove NH(4)(+) as well as PO(4)(3-) from solution in concentrations sufficient for application in water purification. Both NH(4)(+) and PO(4)(3-) removal showed little variation with pH between 5 and 9. Alternative processing methods of zeolite synthesis, including the addition of ash to an unfiltered Si-NaOH solution and addition of a dry ash/diatomite mixture to NaOH solution, were tested. The third process yielded materials with lower cation exchange capacity due to formation of hydroxysodalite. The second process results in a product with relatively high cation exchange capacity, and reduces the number of processing steps necessary for zeolite synthesis.

  15. The Effect of Methanol Gasoline on Low Temperature Performance of Engine Oil%甲醇汽油对发动机油低温性能的影响

    Institute of Scientific and Technical Information of China (English)

    尹兴林; 王娇; 董元虎

    2011-01-01

    In order to study the effect of methanol gasoline on the low temperature performance of engine oil, methanol gasoline and its simulated combustion products of formaldehyde and formic acid were added into the engine oils, and the pour point, solidification point and low temperature dynamic viscosity of the oil samples were analyzed.The results show that the pour point and solidification point have little change with adding methanol gasoline and its simulated combustion products of formaldehyde and formic acid to the oil samples.The low temperature dynamic viscosity has slight increase with the increase of methanol in methanol gasoline, and it is high as the mass fraction of formic acid is between 0.8% ~ 1.2%,but the whole increase tendency is gentle with the increase of formic acid.So the methanol gasoline and its simulated combustion products have little influence on the low temperature performance of engine oils.%为考察甲醇汽油对发动机油低温性能的影响,通过向发动机油中添加甲醇汽油及其模拟燃烧产物甲酸、甲醛,分析其对油样的倾点、凝点、低温动力黏度的影响.结果表明:甲醇汽油及其模拟燃烧产物甲醛、甲酸对油样的倾点、凝点影响较小;随着甲醇添加量的增加,油样的低温动力黏度有增大的趋势;在甲酸质量分数为0.8%~1.2%时,油样的低温动力黏度值较大,但其增大的趋势平缓.因此甲醇汽油及其模拟燃烧产物对发动机油的低温性能影响不大.

  16. Low temperature synthesis of nanocrystalline scandia-stabilized zirconia by aqueous combustion method and its characterizations

    Indian Academy of Sciences (India)

    Quazi Arif Islam; Mir Wasim Raja; Chiranjib Satra; Rajendra Nath Basu

    2015-10-01

    Zirconia stabilized with 11 mol% scandia (11ScSZ) has been successfully synthesized by novel alanine-assisted soft chemical aqueous combustion method. The reaction kinetics during combustion synthesis has been studied in detail by analysing thermal behaviour of different metal–alanine complexes. A single phase 11ScSZ powder is achieved at significantly low calcination temperature of 500° C. Field emission scanning electron micrograph reveals an agglomerated morphology with particle size ranging from 80 to 100 nm. The thermal expansion coefficient is found to be 11.03 × 10−6 °C−1 in the temperature range between room temperature and 1000° C. Optical bandgap of 5.19 eV has been determined using UV–Vis spectroscopy and results are compared with the help of theoretical density of states. The total electrical conductivity of sintered pellet is found to be 7.3 × 10−3 S cm−1 at 700° C as measured by impedance spectroscopy.

  17. Low temperature synthesis and sintering of d-UO2 nanoparticles.

    Energy Technology Data Exchange (ETDEWEB)

    Nenoff, Tina Maria; Ferreira, Summer Rhodes; Robinson, David B. (Sandia National Laboratories, Livermore CA); Jacobs, Benjamin W. (Sandia National Laboratories, Livermore CA); Provencio, Paula Polyak; Huang, Jian Yu

    2010-12-01

    We report on the novel room temperature method of synthesizing advanced nuclear fuels; a method that virtually eliminates any volatility of components. This process uses radiolysis to form stable nanoparticle (NP) nuclear transuranic (TRU) fuel surrogates and in-situ heated stage TEM to sinter the NPs. The radiolysis is performed at Sandia's Gamma Irradiation Facility (GIF) 60Co source (3 x 10{sup 6} rad/hr). Using this method, sufficient quantities of fuels for research purposes can be produced for accelerated advanced nuclear fuel development. We are focused on both metallic and oxide alloy nanoparticles of varying compositions, in particular d-U, d-U/La alloys and d-UO2 NPs. We present detailed descriptions of the synthesis procedures, the characterization of the NPs, the sintering of the NPs, and their stability with temperature. We have employed UV-vis, HRTEM, HAADF-STEM imaging, single particle EDX and EFTEM mapping characterization techniques to confirm the composition and alloying of these NPs.

  18. Fullerene freejets-based synthesis of silicon carbide: heteroepitaxial growth on Si(111) at low temperatures

    Energy Technology Data Exchange (ETDEWEB)

    Aversa, L.; Verucchi, R.; Boschetti, A.; Podesta, A.; Milani, P.; Iannotta, S

    2003-08-15

    The growth of silicon carbide (SiC), a large band-gap semiconductor, on Si is very promising for applications to sensors, electronics and optoelectronics. However, difficulties in controlling the growth of the material and the interface have inhibited the production of SiC based devices. We have developed a new technique (Supersonic Molecular Beam Epitaxy, SuMBE) for the heteroepitaxial growth of SiC on Si by means of supersonic molecular beams of fullerene (C{sub 60}). The carbide synthesis can be induced by the kinetic activation of the process due to the kinetic energy released in C{sub 60}-Si collision. This has made possible a reduction of the growth substrate temperature and an improvement of electronic and structural properties of the SiC film. We present a study of the processes governing the growth of very thin SiC film by C{sub 60} supersonic beam. Two films were grown in Ultra High Vacuum (UHV) on Si(111)-7x7, at substrate temperature of 800 deg. C, using the same fullerene beam but selecting C{sub 60} particles having different characteristics. Surface electronic and structural characterizations were done both in situ and ex situ. The results show that strongly different growth processes can be achieved by controlling the precursor kinetic energy.

  19. Low-temperature solution synthesis and characterization of Ce-doped YAG nanoparticles

    Institute of Scientific and Technical Information of China (English)

    吉成; 冀立宇; 连刘超; 沈丽明; 张晓艳; 王一峰

    2015-01-01

    Monophasic Ce3+-doped yttrium aluminum garnet (Ce:YAG) nanoparticles with high crystallinity and tunable grain size ranging from ~19–30 nm were prepared by a modified co-precipitation process with a follow-up calcination treatment. For the syn-thesis, aluminum, yttrium, and cerium nitrates were used as starting materials, ammonium sulfate as dispersant, and a combination of ammonium bicarbonate and ammonia as precipitating agent. Influence of precipitation temperature, the pH value of precipitant solu-tions, aging period, calcination conditions, and Ce-doping level were investigated for controlling the purity, particle size, and photo-luminescence performance of the Ce:YAG nanoparticles. High-purity YAG nanoparticles were prepared at pH=10.50–11.00 and cal-cination temperatures of 850–1100 ºC with a calcination time of 3 h. With increasing Ce3+ concentration, the peak in the emission spectra of the obtained nanopowders shifted from 529 nm for the 0.67 wt.%-Ce:YAG to 544 nm for the 3.4 wt.%-Ce:YAG, while the strongest photoluminescence intensity was observed for the 1.3 wt.%-Ce:YAG nanoparticles.

  20. 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.

  1. Low Temperature Synthesis and Characterization of AlScMo3O12

    Directory of Open Access Journals (Sweden)

    Rebecca Truitt

    2015-02-01

    Full Text Available Recent interest in low and negative thermal expansion materials has led to significant research on compounds that exhibit this property, much of which has targeted the A2M3O12 family (A = trivalent cation, M = Mo, W. The expansion and phase transition behavior in this family can be tuned through the choice of the metals incorporated into the structure. An undesired phase transition to a monoclinic structure with large positive expansion can be suppressed in some solid solutions by substituting the A-site by a mixture of two cations. One such material, AlScMo3O12, was successfully synthesized using non-hydrolytic sol-gel chemistry. Depending on the reaction conditions, phase separation into Al2Mo3O12 and Sc2Mo3O12 or single-phase AlScMo3O12 could be obtained. Optimized conditions for the reproducible synthesis of stoichiometric, homogeneous AlScMo3O12 were established. High resolution synchrotron diffraction experiments were carried out to confirm whether samples were homogeneous and to estimate the Al:Sc ratio through Rietveld refinement and Vegard’s law. Single-phase samples were found to adopt the orthorhombic Sc2W3O12 structure at 100 to 460 K. In contrast to all previously-reported A2M3O12 compositions, AlScMo3O12 exhibited positive thermal expansion along all unit cell axes instead of contraction along one or two axes, with expansion coefficients (200–460 K of αa = 1.7 × 10−6 K−1, αb = 6.2 × 10−6 K−1, αc = 2.9 × 10−6 K−1 and αV = 10.8 × 10−6 K−1, respectively.

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

    Energy Technology Data Exchange (ETDEWEB)

    Yan, Ting; Guo, Xiaode, E-mail: guoxiaodenj@sina.com; Zhang, Xiang; Wang, Zhixiang; Shi, Jinqiu

    2016-01-15

    Highlights: • The nano α-Al{sub 2}O{sub 3} with good dispersion was prepared by two-step hydrolysis. • α-Al{sub 2}O{sub 3} powders were added as seed particles in the hydrolysis. • This article indicated that the glucose could impel the γ-Al{sub 2}O{sub 3} transformed to α-Al{sub 2}O{sub 3} directly. • This article indicated that the addictive of α-Al{sub 2}O{sub 3} seed could improve the phase transformation rate of γ-Al{sub 2}O{sub 3} to α-Al{sub 2}O{sub 3}. • In this article, the pure α-Al{sub 2}O{sub 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.

  3. The Surface-to-volume Ratio of the Synthesis Reactor Vessel Governing the Low Temperature Crystallization of ZSM-5

    Directory of Open Access Journals (Sweden)

    Ana Hidayati Mukaromah

    2016-12-01

    Full Text Available Zeolite ZSM-5 is one of major catalysts in petroleum and fine-chemical industries. The synthesis of zeolite ZSM-5 is usually carried out at high temperature above 100 °C using the immense amount of organic structure-directing agents (OSDA. It is interesting to note that fine-tuning the initial gel mixture can be used to enhance the typical slow crystallization rate of ZSM-5. Herein, we report the effect of the surface-to-volume ratio of the reactor vessel to the crystallization of ZSM-5 at low temperature. The surface-to-volume ratio of the reactor vessel could influence the heat-transfer during the synthesis which further governed the crystallization of ZSM-5. It was found that the higher the surface-to-volume of the reactor, the more crystalline of the resulting products. The product with the highest crystallinity exhibited a nearly-spherical morphology composed of smaller ZSM-5 crystallites. This phenomenon allowed the presence of inter-crystallite mesopores which is an advantage for the catalytic reaction using bulky molecules.

  4. 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

    2017-08-19

    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.

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

    Energy Technology Data Exchange (ETDEWEB)

    Liu, Jinsong, E-mail: jsliu@nuaa.edu.cn [Department of Materials Science and Technology, Nanjing University of Aeronautics and Astronautics, Nanjing, Jiangsu 210016 (China); State Key Laboratory of Mechanics and Control of Mechanical Structures, Nanjing University of Aeronautics and Astronautics, Nanjing, Jiangsu 210016 (China); Zhu, Kongjun, E-mail: kjzhu@nuaa.edu.cn [State Key Laboratory of Mechanics and Control of Mechanical Structures, Nanjing University of Aeronautics and Astronautics, Nanjing, Jiangsu 210016 (China); Sheng, Beibei [Department of Materials Science and Technology, Nanjing University of Aeronautics and Astronautics, Nanjing, Jiangsu 210016 (China); Li, Ziquan [Department of Materials Science and Technology, Nanjing University of Aeronautics and Astronautics, Nanjing, Jiangsu 210016 (China); Chemical Engineering Department, Nanjing College of Chemical Technology, Nanjing, Jiangsu 210048 (China); Tai, Guoan; Qiu, Jinhao; Wang, Jing [State Key Laboratory of Mechanics and Control of Mechanical Structures, Nanjing University of Aeronautics and Astronautics, Nanjing, Jiangsu 210016 (China); Chen, Jiankang; You, Yuncheng [Department of Materials Science and Technology, Nanjing University of Aeronautics and Astronautics, Nanjing, Jiangsu 210016 (China); Gu, Qilin; Liu, Pengcheng [State Key Laboratory of Mechanics and Control of Mechanical Structures, Nanjing University of Aeronautics and Astronautics, Nanjing, Jiangsu 210016 (China)

    2015-01-05

    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.

  6. Mechanistic Studies of Methanol Synthesis over Cu from CO/CO2/H2/H2O Mixtures: the Source of C in Methanol and the Role of Water

    Energy Technology Data Exchange (ETDEWEB)

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

    2013-02-01

    The low temperature (403 – 453K) conversions of CO:hydrogen and CO2:hydrogen mixtures (6 bar total pressure) to methanol over copper catalysts are both assisted by the presence of small amounts of water (mole fraction ~0.04%-0.5%). For CO2:hydrogen reaction mixtures, the water product from both methanol synthesis and reverse water gas shift serves to initiate both reactions in an autocatalytic manner. In the case of CO:D2 mixtures, very little methanol is produced until small amounts of water are added. The effect of water on methanol production is more immediate than in CO2:D2, yet the steady state rates are similar. Tracer experiments in 13CO:12CO2:hydrogen (with or without added water), show that the dominant source of C in the methanol product gradually shifts from CO2 to CO as the temperature is lowered. Cu-bound formate, the major IR visible surface species under CO2:hydrogen, is not visible in CO:moist hydrogen. Though formate is visible in the tracer experiments, the symmetric stretch is absent. These results, in conjunction with recent DFT calculations on Cu(111), point to carboxyl as a common intermediate for both methanol synthesis and reverse water gas shift, with formate playing a spectator co-adsorbate role.

  7. Phases in the active liquid phase methanol synthesis catalyst

    Energy Technology Data Exchange (ETDEWEB)

    Sawant, A.V.; Lee, S.; Kulik, C.J.

    1988-01-01

    An attempt has been made to identify the phases present in the active catalyst for liquid phase methanol synthesis. X-ray powder diffraction was used to identify the phases. Only metallic Cu was detected, while no Cu/sup +/ species was found to be present. A significant amount of ZnCO/sub 3/ was found to be present in catalysts which had been subjected to high partial pressures of CO/sub 2/. This fact has hitherto not been reported in literature. Some speculations about the effect of ZnCO/sub 3/ on the life of the catalyst are made. 21 refs., 6 figs.

  8. 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

    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

  9. Proton-conducting Membranes Based on PVA-PAMPS Semi-interpenetrating Polymer Networks for Low Temperature Direct Methanol Fuel Cells

    Institute of Scientific and Technical Information of China (English)

    Jinli Qiao; Tatsuhiro Okada

    2005-01-01

    @@ 1Introduction In direct methanol fuel cells (DMFCs) the methanol crossover from anode to cathode through the polymer electrolyte membrane is a major isue, because this not only causes loss of fuel, but also reduces the performance at the cathode due to the mixed reaction of methanol oxidation with oxygen reduction reaction. Membranes that show high proton conductivity, and at the same time, low methanol permeability are strongly desired but difficult to attain, because of trade-off relations between these parameters. We here report a new type of cost-effective polymer blend membranes based on chemically cross-linked poly(vinyl alcohol) (PVA)and 2-acrylamido-2-methyl-1-propanesulfonic acid (PAMPS) which is called semi-interpenetrating polymer networks (semi-IPNs). The membrane structure is finished by cross-linking the hydroxyl groups of poly (vinyl alchol) (PVA) main chain with acetal ring formation using glutaraldehyde (GA) cross-linker. For improving the flexibility of the membranes, we reported "binary chemcial cross-linking", "hydrophobicizer" and "stabilizer"effect[1-3], respectively, in our recent work.

  10. Low-temperature solid state synthesis and in situ phase transformation to prepare nearly pure cBN.

    Science.gov (United States)

    Lian, Gang; Zhang, Xiao; Tan, Miao; Zhang, Shunjie; Cui, Deliang; Wang, Qilong

    2011-07-14

    Cubic boron nitride (cBN) is synthesized by a low-temperature solid state synthesis and in situ phase transformation route with NH(4)BF(4), B, NaBH(4) and KBH(4) as the boron sources and NaN(3) as the nitrogen source. Furthermore, two new strategies are developed, i.e., applying pressure on the reactants during the reaction process and introducing the structural induction effect. These results reveal that the relative contents of cBN are greatly increased by applying these new strategies. Finally, almost pure cBN (∼90%) crystals are obtained by reacting NH(4)BF(4) and NaN(3) at 250 °C and 450 MPa for 24 h, with NaF as the structural induction material. The heterogeneous nucleation mechanism can commendably illuminate the structure induction effect of NaF with face center cubic structure. In addition, the induction effect results in the cBN nanocrystals presenting obvious oriented growth of {111} planes.

  11. Superfast assembly and synthesis of gold nanostructures using nanosecond low-temperature compression via magnetic pulsed power

    Science.gov (United States)

    Li, Binsong; Bian, Kaifu; Lane, J. Matthew D.; Salerno, K. Michael; Grest, Gary S.; Ao, Tommy; Hickman, Randy; Wise, Jack; Wang, Zhongwu; Fan, Hongyou

    2017-01-01

    Gold nanostructured materials exhibit important size- and shape-dependent properties that enable a wide variety of applications in photocatalysis, nanoelectronics and phototherapy. Here we show the use of superfast dynamic compression to synthesize extended gold nanostructures, such as nanorods, nanowires and nanosheets, with nanosecond coalescence times. Using a pulsed power generator, we ramp compress spherical gold nanoparticle arrays to pressures of tens of GPa, demonstrating pressure-driven assembly beyond the quasi-static regime of the diamond anvil cell. Our dynamic magnetic ramp compression approach produces smooth, shockless (that is, isentropic) one-dimensional loading with low-temperature states suitable for nanostructure synthesis. Transmission electron microscopy clearly establishes that various gold architectures are formed through compressive mesoscale coalescences of spherical gold nanoparticles, which is further confirmed by in-situ synchrotron X-ray studies and large-scale simulation. This nanofabrication approach applies magnetically driven uniaxial ramp compression to mimic established embossing and imprinting processes, but at ultra-short (nanosecond) timescales. PMID:28300067

  12. Superfast assembly and synthesis of gold nanostructures using nanosecond low-temperature compression via magnetic pulsed power

    Science.gov (United States)

    Li, Binsong; Bian, Kaifu; Lane, J. Matthew D.; Salerno, K. Michael; Grest, Gary S.; Ao, Tommy; Hickman, Randy; Wise, Jack; Wang, Zhongwu; Fan, Hongyou

    2017-03-01

    Gold nanostructured materials exhibit important size- and shape-dependent properties that enable a wide variety of applications in photocatalysis, nanoelectronics and phototherapy. Here we show the use of superfast dynamic compression to synthesize extended gold nanostructures, such as nanorods, nanowires and nanosheets, with nanosecond coalescence times. Using a pulsed power generator, we ramp compress spherical gold nanoparticle arrays to pressures of tens of GPa, demonstrating pressure-driven assembly beyond the quasi-static regime of the diamond anvil cell. Our dynamic magnetic ramp compression approach produces smooth, shockless (that is, isentropic) one-dimensional loading with low-temperature states suitable for nanostructure synthesis. Transmission electron microscopy clearly establishes that various gold architectures are formed through compressive mesoscale coalescences of spherical gold nanoparticles, which is further confirmed by in-situ synchrotron X-ray studies and large-scale simulation. This nanofabrication approach applies magnetically driven uniaxial ramp compression to mimic established embossing and imprinting processes, but at ultra-short (nanosecond) timescales.

  13. Stereospecific growth of densely populated rutile mesoporous TiO2 nanoplate films: a facile low temperature chemical synthesis approach

    Science.gov (United States)

    Lee, Go-Woon; Ambade, Swapnil B.; Cho, Young-Jin; Mane, Rajaram S.; Shashikala, V.; Yadav, Jyotiprakash; Gaikwad, Rajendra S.; Lee, Soo-Hyoung; Jung, Kwang-Deog; Han, Sung-Hwan; Joo, Oh-Shim

    2010-03-01

    We report for the first time, using a simple and environmentally benign chemical method, the low temperature synthesis of densely populated upright-standing rutile TiO2 nanoplate films onto a glass substrate from a mixture of titanium trichloride, hydrogen peroxide and thiourea in triply distilled water. The rutile TiO2 nanoplate films (the phase is confirmed from x-ray diffraction analysis, selected area electron diffraction, energy-dispersive x-ray analysis, and Raman shift) are 20-35 nm wide and 100-120 nm long. The chemical reaction kinetics for the growth of these upright-standing TiO2 nanoplate films is also interpreted. Films of TiO2 nanoplates are optically transparent in the visible region with a sharp absorption edge close to 350 nm, confirming an indirect band gap energy of 3.12 eV. The Brunauer-Emmet-Teller surface area, Barret-Joyner-Halenda pore volume and pore diameter, obtained from N2 physisorption studies, are 82 m2 g - 1, 0.0964 cm3 g - 1 and 3.5 nm, respectively, confirming the mesoporosity of scratched rutile TiO2 nanoplate powder that would be ideal for the direct fabrication of nanoscaled devices including upcoming dye-sensitized solar cells and gas sensors.

  14. Synthesis, Characterization, and Low Temperature Sintering of Nanostructured BaWO4 for Optical and LTCC Applications

    Directory of Open Access Journals (Sweden)

    S. Vidya

    2013-01-01

    Full Text Available Synthesis of nano-BaWO4 by a modified combustion technique and its suitability for various applications are reported. The structure and phase purity of the sample analyzed by X-ray diffraction, Fourier transform Raman, and infrared spectroscopy show that the sample is phase pure with tetragonal structure. The particle size from the transmission electron microscopy is 22 nm. The basic optical properties and optical constants of the nano BaWO4 are studied using UV-visible absorption spectroscopy which showed that the material is a wide band gap semiconductor with band gap of 4.1 eV. The sample shows poor transmittance in ultraviolet region while maximum in visible-near infrared regions. The photoluminescence spectra show intense emission in blue region. The sample is sintered at low temperature of 810°C, without any sintering aid. Surface morphology of the sample is analyzed by scanning electron microscopy. The dielectric constant and loss factor measured at 5 MHz are 9 and 1.56×10-3. The temperature coefficient of dielectric constant is −22 ppm/°C. The experimental results obtained in the present work claim the potential use of nano BaWO4 as UV filters, transparent films for window layers on solar cells, antireflection coatings, scintillators, detectors, and for LTCC applications.

  15. Low temperature synthesis of hierarchical TiO2 nanostructures for high performance perovskite solar cells by pulsed laser deposition.

    Science.gov (United States)

    Yang, Bin; Mahjouri-Samani, Masoud; Rouleau, Christopher M; Geohegan, David B; Xiao, Kai

    2016-10-21

    A promising way to advance perovskite solar cells is to improve the quality of the electron transport material -e.g., titanium dioxide (TiO2) - in a direction that increases electron transport and extraction. Although dense TiO2 films are easily grown in solution, efficient electron extraction suffers due to a lack of interfacial contact area with the perovskites. Conversely, mesoporous films do offer high surface-area-to-volume ratios, thereby promoting efficient electron extraction, but their morphology is relatively difficult to control via conventional solution synthesis methods. Here, a pulsed laser deposition method was used to assemble TiO2 nanoparticles into TiO2 hierarchical architectures exhibiting an anatase crystal structure, and prototype solar cells employing these structures yielded power conversion efficiencies of ∼14%. Our approach demonstrates a way to grow high aspect-ratio TiO2 nanostructures for improved interfacial contact between TiO2 and perovskite materials, leading to high electron-hole pair separation and electron extraction efficiencies for superior photovoltaic performance. Compared to previous pulsed laser deposition-synthesized TiO2 mesoporous crystalline networks that needed post-thermal annealing at 500 °C to form mesoporous crystalline networks, our relatively low temperature (300 °C) TiO2 processing method may promote reduced energy-consumption during device fabrication, as well as enable compatibility with flexible polymer substrates such as polyimide.

  16. Enhanced conversion via three-phase methanol synthesis

    Energy Technology Data Exchange (ETDEWEB)

    Elliott, J.R.; Berty, J.M.; Chandrasekhar, K.; Rastogi, R.; Khosla, P. (Akron Univ., OH (USA). Dept. of Chemical Engineering)

    1988-01-01

    A three-phase methanol process has been envisaged to enhance the single pass conversion of hydrogen and carbon monoxide. The use of an inert, high boiling solvent that preferentially absorbs the methanol as soon as it is formed, helps lower product inhibition of the forward reaction, increases conversion and virtually eliminates the need for recycle of unconverted reactants. The solvent also removes carbon dioxide to an appreciable extent. This suggests that two pre-synthesis steps might be eliminated resulting in additional savings. The proposed process involves simultaneous reaction and phase equilibria. Pertinent VLE data involving syngas, methanol, water and solvent have been obtained experimentally in the temperature range of 200-240{sup 0}C and pressure range of 50-100 atmospheres and checked against the Modified Soave-Redlich-Kwong equation of state. Indications are that the desired partitioning of the species, is attainable. CSTR simulation of the process using known vapor phase kinetics has shown that conversions as high as 90% can be achieved in a single stage. Semibatch three phase reactions have been carried out in an internal recycle reactor using copper catalyst. Conversions greater than 90% were achieved verifying the single stage simulation results.

  17. A Hydrogen-power Cogeneration System Set up by Combining Medium-and-low Temperature Waste Heat with Methanol Reforming%中低温废热与甲醇重整结合的氢电联产系统

    Institute of Scientific and Technical Information of China (English)

    廖腾飞; 洪慧; 刘柏谦

    2009-01-01

    A new approach was presented for combining the medium-and-low temperature waste heat in sintered gas with methanol steam reforming to produce hydrogen.A hydrogen production system by combining medium-and-low temperature waste heat with methanol reforming was established and simulated.On the basis of an energy grade concept and by using an energy utilization diagram(EUD) image-based exergy analytic method,revealed were the energy conversion characteristics featuring the conversion of low grade medium-and-low temperature waste heat to high grade chemical energy.Studied was the variation law governing the upgrading of medium-and-low temperature waste heat with methanol reforming reaction temperatures.The research results show that the exergy efficiency of the new type hydrogen production system is expected to reach 82.8%,12 percentage points higher than that of a traditional methanol-based hydrogen-production system.The energy-saving rate of methanol fuel is 23.7%.In addition,a preliminary static economic analysis indicates that the hydrogen production cost of the new system is about RMB 1.5 yuan/m~3,far lower than that of water electrolysis(RMB 5.5 yuan/m~3).When the cost of raw material methanol price is maintained within a certain price range,the hydrogen production cost can be competitive with the traditional natural gas-based hydrogen production cost of RMB 1.2 yuan/m~3.The foregoing can provide a new approach to the metallurgical industry for both solving a technically intractable problem of utilizing medium-and-low temperature waste heat and coping with a high energy consumption for hydrogen production.%提出了烧结机烟气中低温废热与甲醇蒸汽重整制氢整合的新方法,模拟建立了中低温废热结合甲醇重整制氢的系统.基于能的品位概念,采用EUD图像火用分析方法,揭示低品位的中低温废热转化为高品位化学能的能量转换特性;研究了中低温废热品位的提升随甲醇重整反应温度的变

  18. Modeling of a Reverse Flow Reactor for Methanol Synthesis

    Institute of Scientific and Technical Information of China (English)

    陈晓春; P.L.Silveston; 等

    2003-01-01

    An accurate one-dimensional,heterogeneous model taking account of axial dispersion and heat transfer to the reactor wall,and heat conduction through the reactor wall for methanol synthesis in a bench scale reactor under periodic reversal of flow direction is presented.Adjustable parameters in this model are the effectiveness factors for each of the three reactions occurring in the synthesis and a factor for the bed to wall heat transfer coefficient correlation.Experimental data were used to evaluate these parameters and reasonable values of these parameters were obtained.The model was found to closely predict the reactor performance under a wide range of parameters were obtained.The model was found to closely predict the reactor preformance under a wide range of operating conditions,such as carbon oxide concentrations,volumetric flow rate,and cyclic period.

  19. 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.

  20. Analysis of Test Run Problems and Solution Measures of Low-Temperature Methanol Wash Unit%低温甲醇洗装置试车问题分析及解决措施

    Institute of Scientific and Technical Information of China (English)

    王学军; 乔洪凯; 郭晓鹏

    2012-01-01

    A comparison is made of low-temperature methanol wash and NHD processes for removal of acid gases in large plants for chemical processing of coal. A description is given of the process flow and special features of the low-temperature methanol wash unit. Experience in the test run is presented, with emphasis on the problems encountered and their solutions, such as water plugging in the tube pass of heat exchanger ( E6 ) during start-up, thorough absorption of CO2 in gas delivery to the system, insufficient accuracy in adjustment of the butterfly valve and inability of two-way sealing of valves in the battery limit.%对大型煤化工酸性气体脱除采用的低温甲醇洗与NHD工艺进行了对比,概述了低温甲醇洗装置的工艺流程及特点.介绍了低温甲醇洗装置试车经验,重点阐述开车过程中出现的换热器(E6)管程水堵塞、系统导气时CO2彻底吸收、蝶阀调节精度不足和界区阀不能双向密封等问题及解决措施.

  1. Bench scale demonstration of the Supermethanol concept : The synthesis of methanol from glycerol derived syngas

    NARCIS (Netherlands)

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

    2012-01-01

    An integrated process for the synthesis of methanol from aqueous glycerol involving reforming of the feed to syngas followed by methanol synthesis is successfully demonstrated in a continuous bench scale unit. Glycerol reforming was carried out at pressures of 24-27 MPa and temperatures of 948-998 K

  2. Basic features of low-temperature plasma formation in the course of composite coating synthesis at the active faces of complex contoured hard tools

    Science.gov (United States)

    Brzhozovsky, B. M.; Zimnyakov, D. A.; Zinina, E. P.; Martynov, V. V.; Pleshakova, E. S.; Yuvchenko, S. A.

    2016-04-01

    Basic features of combined-discharge low-temperature plasma formation around the surfaces of complex-contoured metal units are considered. It is shown that it makes the possibilities for synthesis of hardened high-durable coatings of hard tools appropriate for material processing in extreme load-temperature conditions. Experimental study of the coating formation was carried out in combination with the analysis of emission spectra of a low-temperature plasma cloud. Some practical examples of the coating applications are presented.

  3. Sum-Up of Use of Double Absorption Low-Temperature Methanol Wash Process%双吸收低温甲醇洗工艺应用总结

    Institute of Scientific and Technical Information of China (English)

    陈胜军

    2013-01-01

    介绍了双吸收低温甲醇洗工艺流程,并对其工艺要点进行分析.结合生产过程中洗涤后的净化气中CO2含量超标、甲醇损失量大、系统甲醇液位波动及系统腐蚀等问题进行分析,提出了相应的解决措施.%The process flowsheet is presented of double absorption low-temperature methanol wash,and an analysis is given of its process essentials.An analysis is carried out of its problems in process,viz.,the CO2 content of the purified gas after scrubbing exceeds the standard,loss of methanol is high,liquid level of methanol in the system flutters,and the system is corroded,so relevant measures for their solution are put forward.

  4. Low temperature synthesis and sintering behaviour of Gd-doped ceria nanosized powders: comparison between two synthesis procedures

    Directory of Open Access Journals (Sweden)

    Tartaj, J.

    2009-04-01

    Full Text Available Two different routes of synthesis of Ce0.9Gd0.1O1.95 (CGO nanopowders are presented; the ethylene glycol-metal nitrate polymerized complex solution method and the precipitation technique using ammonia as the precipitant agent. The powders characteristics were examined by X-ray diffraction (XRD, transmission electron microscopy (TEM, Brunauer-Emmett-Teller (BET surface area and simultaneous thermogravimetric and differential thermal analysis (TG/DTA. Scanning electron microscopy (SEM observations were used to determine the agglomeration degree of the powders, and the uniformity of the green compacts. The Hg-porosimetry results were used to investigate the pore size. The densification process was studied by constant heating rate dilatometry and isothermal sintering at different temperatures. Microstructural development of each sample at different sintering temperatures and times was followed by SEM.

    Se presentan dos diferentes rutas de síntesis de nanopolvos de Ce0.9Gd0.1O1.95 (CGO: precipitación de hidróxidos, a partir de soluciones de nitratos utilizando amonia como agente precipitante y formación de complejos polimerizados etilene-glicol nitratos metálicos. Las características de los polvos se determinaron por DRX, microscopía de transmisión (TEM, superficie específica por Brunauer-Emmett-Teller (BET, y ensayos de ATD/ATG. El grado de aglomeración de los nanopolvos y la uniformidad de los compactos en verde se ha observado por Microscopía electrónica de barrido, (SEM. El tamaño de poro de los compactos en verde se ha medido mediante porosimetría de Hg. El comportamiento a la sinterización se ha evaluado por dilatometría a velocidad de calentamiento constante y por sinterización isoterma a diferentes temperaturas. La evolución microestructural se ha seguido por SEM.

  5. 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

  6. 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.

  7. 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.)

  8. Ceramic materials of low-temperature synthesis for dielectric coating applied by 3D aerosol printing used in nano- and microelectronics, lighting engineering, and spacecraft control devices

    Science.gov (United States)

    Ivanov, A. A.; Tuev, V. I.; Nisan, A. V.; Potapov, G. N.

    2016-11-01

    A synthesis technique of low-temperature ceramic material based on aluminosilicates of dendrimer morphology capable to contain up to 80 wt % of nitrides and oxides of high-melting compounds as filler has been developed. The synthesis is based on a sol-gel method followed by mechanochemical treatment and ultrasonic dispersing. Dielectric ceramic layers with the layer thickness in the nanometer range and high thermal conductivity have been obtained for the first time by 3D aerosol printing of the synthesized material. The study of the obtained ceramic coating on the metal surface (Al) has proved its use prospects in microelectronics, light engineering, and devices for special purposes.

  9. 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)

  10. High-performance hybrid oxide catalyst of manganese and cobalt for low-pressure methanol synthesis

    National Research Council Canada - National Science Library

    Li, Cheng-Shiuan; Melaet, Gérôme; Ralston, Walter T; An, Kwangjin; Brooks, Christopher; Ye, Yifan; Liu, Yi-Sheng; Zhu, Junfa; Guo, Jinghua; Alayoglu, Selim; Somorjai, Gabor A

    2015-01-01

    ... in the scanning transmission electron microscopy mode. Through control experiments, we find that the catalyst's chemical nature and architecture are the key factors in enabling the enhanced methanol synthesis and ethylene production...

  11. Understanding the activity of Zn-Cu sites in methanol synthesis

    NARCIS (Netherlands)

    Batyrev, E.D.

    2013-01-01

    This thesis deals with the Cu/ZnO interaction in activated methanol synthesis catalysts. A combination of classical characterization techniques and surface science techniques was applied to probe the dynamic modification of catalyst structure upon the activation in hydrogen.

  12. Concentration-driven phase control for low temperature synthesis of phase-pure anatase and rutile titanium oxide.

    Science.gov (United States)

    Wang, Zhifeng; Xiao, Chunyan; Yamada, Shuhei; Yoshinaga, Kohji; Bu, Xiu R; Zhang, Ming

    2015-06-15

    It is highly desirable to develop controlled synthetic methods at low temperature (anatase without the use of any additives or surfactants or external acids. The formation of crystalline phases is found to be dependent on reaction temperature and highly dependent on concentration. Phase-pure rutile is obtained in two concentration zones while phase-pure anatase is obtained in one concentration zone. The relationship between phases and reaction conditions (concentration and temperature) fits well with the nucleation diffusion rate model.

  13. 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.

  14. Study on methanol synthesis from coal-based syngas

    Institute of Scientific and Technical Information of China (English)

    MA Hong-fang; YING Wei-yong; FANG Ding-ye

    2009-01-01

    The intrinsic kinetic models of the Langmuir-Hinshelwood type were investi-gated in terms of the reaction rates of CO hydrogenation and CO2 hydrogenation in the form of reactant fugacity.The parameters were estimated by the Universal Global Optimi-zation 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 com-bined 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 de-scribe the transfer process of multi-component diffusion system in the catalyst.The calcu-lated value computed by the internal diffusion efficiency factor calculation model estab-lished for methanol synthesis catalyst fit the experimental value very well.

  15. EFFECT OF OXYGEN DONOR ALCOHOLS ON LOW TEMPERATURE NONHYDROLYTIC SOL-GEL SYNTHESIS OF ALUMINUM TITANATE%氧供体醇对非水解溶胶-凝胶法低温合成钛酸铝的影响

    Institute of Scientific and Technical Information of China (English)

    江伟辉; 魏恒勇; 冯果; 周艳华; 于云

    2008-01-01

    Aluminum titanate has been synthesized at low temperature by nonhydrolytic sol-gel route using titanium tetrachloride and anhydrous aluminum trichloride as raw materials and anhydrous alcohols as oxygen donors. The effects of different anhydrous alcohols and their quantities on the low temperature synthesis of Al2TiO5 were studied. The results show that while the oxygen donor used is in stoichiometric ratio for synthesizing Al2TiO5 at 750 ℃, ethanol is the most effective oxygen donor, followed by isopropanol;n-butyl alcohol is a less effective oxygen donor. In contrast, Al2TiO5 can not be synthesized at low temperatures using methanol or tert-butyl alcohol as oxygen donor due to their high chemical reactivity resulting in hydrolysis reaction. When the quantities of alcohols added exceeding the stoichiometric, the effect on synthesis declined dramatically. However, use of less than the stoichiometricquantity of isopropanol and n-butyl alcohol led to the remarkable enhancement effect in the synthesis of Al2TiO5, but no obvious influence was observed when ethanol was used.%以TiCl4和无水AlCl3为原料,以无水低碳醇为氧供体通过非水解溶胶-凝胶法低温合成了钛酸铝,研究了无水低碳醇种类及用量对钛酸铝合成反应的影响.结果表明:当氧供体按反应式化学计量比用量加入时,在750℃能合成出钛酸铝,其中以乙醇的合成效果最好,异丙醇次之,正丁醇的效果较差;采用甲醇和叔丁醇作氧供体,由于它们的化学活性过大而引发水解反应,不能低温(750 ℃)合成钛酸铝.当醇用量超过化学计量比时,则合成效果显著下降;当醇用量低于化学计量比时,改变乙醇的用量对合成效果影响不明显,而减少异丙醇和正丁醇用量可显著提高钛酸铝的合成效果.

  16. An ecosystem-scale perspective of the net land methanol flux: synthesis of micrometeorological flux measurements

    Directory of Open Access Journals (Sweden)

    G. Wohlfahrt

    2015-01-01

    Full Text Available Methanol is the second most abundant volatile organic compound in the troposphere and plays a significant role in atmospheric chemistry. While there is consensus about the dominant role of living plants as the major source and the reaction with OH as the major sink of methanol, global methanol budgets diverge considerably in terms of source/sink estimates reflecting uncertainties in the approaches used to model, and the empirical data used to separately constrain these terms. Here we compiled micrometeorological methanol flux data from eight different study sites and reviewed the corresponding literature in order to provide a first cross-site synthesis of the terrestrial ecosystem-scale methanol exchange and present an independent data-driven view of the land–atmosphere methanol exchange. Our study shows that the controls of plant growth on the production, and thus the methanol emission magnitude, and stomatal conductance on the hourly methanol emission variability, established at the leaf level, hold across sites at the ecosystem-level. Unequivocal evidence for bi-directional methanol exchange at the ecosystem scale is presented. Deposition, which at some sites even exceeds methanol emissions, represents an emerging feature of ecosystem-scale measurements and is likely related to environmental factors favouring the formation of surface wetness. Methanol may adsorb to or dissolve in this surface water and eventually be chemically or biologically removed from it. Management activities in agriculture and forestry are shown to increase local methanol emission by orders of magnitude; they are however neglected at present in global budgets. While contemporary net land methanol budgets are overall consistent with the grand mean of the micrometeorological methanol flux measurements, we caution that the present approach of simulating methanol emission and deposition separately is prone to opposing systematic errors and does not allow taking full

  17. 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...... for a gas mixture of H2:CO = 1:1. The gas-dependent morphology of the Cu nanoparticles provides a consistent explanation of the observed coupling between the transient methanol production and pretreatment conditions within the framework of the dynamic microkinetic model by Ovesen et al. [J. Catal. 168 (1997...

  18. New Rh-ZnO/Carbon Nanotubes Catalyst for Methanol Synthesis

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    A new catalyst for methanol synthesis, ZnO-promoted rhodium supported on carbon nanotubes, was developed. It was found that the Rh-ZnO/CNTs catalyst had high activity of 411.4 mg CH3OH/g/cat/h and selectivity of 96.7 % for methanol at 1 MPa and 523 K. The activity of this catalyst is much higher than that of NC 207 catalyst at the same reaction conditions. It was suggested that the multi-walled structure CNTs favored both the couple transfer of the proton and electron over the surface of the catalyst and the uptake of hydrogen which was favorable to methanol synthesis.

  19. Synthesis and characterization of zinc ferrite nanoparticles obtained by self-propagating low-temperature combustion method

    Indian Academy of Sciences (India)

    P M Prithviraj Swamy; S Basavaraja; Arunkumar Lagashetty; N V Srinivas Rao; R Nijagunappa; A Venkataraman

    2011-12-01

    The self-propagating low-temperature combustion method was used to produce nanocrystalline particles of zinc ferrite. The products were characterized for chemical and phase composition, morphology and magnetic properties. The results obtained showed the formation of single-phase zinc ferrite nanoparticles with an average particle size of about 40 nm. As-synthesized powder displayed good magnetic property. Due to the simplicity and low cost of this process, it could also become a valuable starting point for the generation of other mixed and complex ferrites.

  20. Low temperature synthesis of fibres composed of carbon-nickel nanoparticles in super-critical carbon dioxide

    Science.gov (United States)

    Hasumura, Takashi; Fukuda, Takahiro; Whitby, Raymond L. D.; Aschenbrenner, Ortrud; Maekawa, Toru

    2010-06-01

    We show that fibres composed of carbon-nickel nanoparticles are self-assembled by mixing nickelocene and oxygen with super-critical carbon dioxide in a dc electric field. The fibres grow in the direction of the electric field and the growth rate increases with an increase in the strength of the electric field. We also irradiate the fibres with electron beams and find that crystallized nickel particles are captured by carbon particles. The present result suggests that a low temperature method of creating carbon-metal hybrid nanostructures may be developed by mixing metallocene and trigger molecules with super-critical fluids subjected to a dc electric field.

  1. Characterization of low temperature graphene synthesis in inductively coupled plasma chemical vapor deposition process with optical emission spectroscopy.

    Science.gov (United States)

    Ma, Yifei; Kim, Daekyoung; Jang, Haegyu; Cho, Sung Min; Chae, Heeyeop

    2014-12-01

    Low-temperature graphene was synthesized at 400 degrees C with inductively coupled plasma chemical vapor deposition (PECVD) process. The effects of plasma power and flow rate of various carbon containing precursors and hydrogen on graphene properties were investigated with optical emission spectroscopy (OES). Various radicals monitored by OES were correlated with graphene film properties such as sheet resistance, I(D)/I(G) ratio of Raman spectra and transparency. C2H2 was used as a main precursor and the increase of plasma power enhanced intensity of carbon (C2) radical OES intensity in plasma, reduced sheet resistance and increased transparency of graphene films. The reduced flow rate of C2H2 decreased sheet resistance and increased transparency of graphene films in the range of this study. H2 addition was found to increase sheet resistance, transparency and attributed to reduction of graphene grain and etching graphene layers. OES analysis showed that C2 radicals contribute to graphite networking and sheet resistance reduction. TEM and AFM were applied to provide credible information that graphene had been successfully grown at low temperature.

  2. Minimizing the Gibbs-Thomson effect in the low-temperature plasma synthesis of thin Si nanowires

    Energy Technology Data Exchange (ETDEWEB)

    Mehdipour, H [Department of Physics, Faculty of Science, Sahand University of Technology, 51335-1996 Tabriz (Iran, Islamic Republic of); Ostrikov, K; Rider, A E; Furman, S A, E-mail: Amanda.Rider@csiro.au [Plasma Nanoscience Center Australia (PNCA), CSIRO Materials Science and Engineering, PO Box 218, Lindfield, New South Wales 2070 (Australia)

    2011-08-05

    An advanced combination of numerical models, including plasma sheath, ion- and radical-induced species creation and plasma heating effects on the surface and within a Au catalyst nanoparticle, is used to describe the catalyzed growth of Si nanowires in the sheath of a low-temperature and low-pressure plasma. These models have been used to explain the higher nanowire growth rates, low-energy barriers, much thinner Si nanowire nucleation and the less effective Gibbs-Thomson effect in reactive plasma processes, compared with those of neutral gas thermal processes. The effects of variation in the plasma sheath parameters and substrate potential on Si nanowire nucleation and growth have also been investigated. It is shown that increasing the plasma-related effects leads to decreases in the nucleation energy barrier and the critical nanoparticle radius, with the Gibbs-Thomson effect diminished, even at low temperatures. The results obtained are consistent with available experimental results and open a path toward the energy- and matter-efficient nucleation and growth of a broad range of one-dimensional quantum structures.

  3. Minimizing the Gibbs-Thomson effect in the low-temperature plasma synthesis of thin Si nanowires

    Science.gov (United States)

    Mehdipour, H.; Ostrikov, K.; Rider, A. E.; Furman, S. A.

    2011-08-01

    An advanced combination of numerical models, including plasma sheath, ion- and radical-induced species creation and plasma heating effects on the surface and within a Au catalyst nanoparticle, is used to describe the catalyzed growth of Si nanowires in the sheath of a low-temperature and low-pressure plasma. These models have been used to explain the higher nanowire growth rates, low-energy barriers, much thinner Si nanowire nucleation and the less effective Gibbs-Thomson effect in reactive plasma processes, compared with those of neutral gas thermal processes. The effects of variation in the plasma sheath parameters and substrate potential on Si nanowire nucleation and growth have also been investigated. It is shown that increasing the plasma-related effects leads to decreases in the nucleation energy barrier and the critical nanoparticle radius, with the Gibbs-Thomson effect diminished, even at low temperatures. The results obtained are consistent with available experimental results and open a path toward the energy- and matter-efficient nucleation and growth of a broad range of one-dimensional quantum structures.

  4. Cyanobacterial monogalactosyldiacylglycerol-synthesis pathway is involved in normal unsaturation of galactolipids and low-temperature adaptation of Synechocystis sp. PCC 6803.

    Science.gov (United States)

    Yuzawa, Yuichi; Shimojima, Mie; Sato, Ryoichi; Mizusawa, Naoki; Ikeda, Keiko; Suzuki, Mamie; Iwai, Masako; Hori, Koichi; Wada, Hajime; Masuda, Shinji; Ohta, Hiroyuki

    2014-04-04

    We characterized certain physiological functions of cyanobacterial monoglucosyldiacylglycerol using a Synechocystis sp. PCC 6803 mutant in which the gene for monoglucosyldiacylglycerol synthase had been disrupted and its function complemented by inclusion of an Arabidopsis monogalactosyldiacylglycerol synthase gene. By using this method, we prepared the first viable monoglucosyldiacylglycerol-deficient mutant of cyanobacterium and found that monoglucosyldiacylglycerol is not essential for its growth and photosynthesis under a set of "normal growth conditions" when monogalactosyldiacylglycerol is adequately supplied by the Arabidopsis monogalactosyldiacylglycerol synthase. The mutant had healthy thylakoid membranes and normal pigment content. The membrane lipid composition of the mutant was similar with that of WT except lack of monoglucosyldiacylglycerol and a slight increase in the level of phosphatidylglycerol at both normal and low temperatures. However, the ratio of unsaturated fatty acids in monogalactosyldiacylglycerol and digalactosyldiacylglycerol was reduced in the mutant compared with WT. Although the growth of the mutant was indistinguishable with that of WT at normal growth temperature, it was markedly retarded at low temperature compared with that of WT. Our data indicated the possibility that cyanobacterial monogalactosyldiacylglycerol-synthesis pathway might be required for the adequate unsaturation level of fatty acids in galactolipids and affect the low-temperature sensitivity. Copyright © 2013 The Author. Published by Elsevier B.V. All rights reserved.

  5. 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.

  6. Low temperature synthesis of flower-like ZnMn 2O 4 superstructures with enhanced electrochemical lithium storage

    Science.gov (United States)

    Xiao, Lifen; Yang, Yanyan; Yin, Jia; Li, Qiao; Zhang, Lizhi

    In this communication, flower-like tetragonal ZnMn 2O 4 superstructures are synthesized by a facile low temperature solvothermal process. Characterizations show that these ZnMn 2O 4 superstructures are well crystallized and of high purity. The product exhibits an initial electrochemical capacity of 763 mAh g -1 and retains stable capacity of 626 mAh g -1 after 50 cycles. Its stable capacity is significantly higher than that of nanocrystalline ZnMn 2O 4 synthesized by a polymer-pyrolysis method. It is found that the higher capacity retention can be attributed to three-dimensional superstructural nature of the as-prepared flower-like ZnMn 2O 4 material. This study suggests that the solvothermally synthesized flower-like ZnMn 2O 4 is a promising anode material for lithium-ion batteries.

  7. Catalysis of the Carbonylation of Alcohols to Carboxylic Acids Including Acetic Acid Synthesis from Methanol.

    Science.gov (United States)

    Forster, Denis; DeKleva, Thomas W.

    1986-01-01

    Monsanto's highly successful synthesis of acetic acid from methanol and carbon monoxide illustrates use of new starting materials to replace pretroleum-derived ethylene. Outlines the fundamental aspects of the acetic acid process and suggests ways of extending the synthesis to higher carboxylic acids. (JN)

  8. Low temperature synthesis of RGO-Au nanocomposite with apparently reduced time and its application as a chemical sensor

    Energy Technology Data Exchange (ETDEWEB)

    Tuz Johra, Fatima; Jung, Woo-Gwang, E-mail: wgjung@kookmin.ac.kr

    2016-01-30

    Graphical abstract: - Highlights: • RGO-Au nanocomposites were synthesized at comparably low temperature. • Different characterization techniques confirm the reduction of graphite oxide. • 10–20 nm average sizes Au nanoparticles are well spread on RGO thin films. • RGO-Au nanocomposite modified electrode shows an enhanced sensing characteristics on detection of Cr(VI). • Porous RGO and electropositive Au help to enhance the detection capability. - Abstract: For the first time, a reduced graphene oxide (RGO)-Au nanocomposites (NC) is synthesized at a low temperature by refluxing without a surfactant. Transmission electron microscopy suggests that Au nanoparticles (NPs) 10–20 nm in size are dispersed on the RGO thin film. X-ray diffraction study, UV–vis spectrometry, and Raman spectroscopy confirmed the reduction of graphene oxide (GO). This RGO-Au NC shows an excellent ability to detect Cr(VI) by electrochemical sensing, with good responses to both current and voltage. A glassy carbon electrode modified with the NC shows a significant voltammetric reduction peak. The voltammetric detection ability is highly dependent on the pH of the electrolyte. The large surface area of RGO's porous structure and the electroactive Au NPs both allow free exchange of reaction intermediates, resulting in significantly enhanced Cr(VI) reduction activity. The RGO-Au electrode shows a good linear response in a range of Cr(VI) concentrations from 10 to 800 μM and a high sensitivity of 0.0146 μA μM{sup −1} with a 2.10 μM detection limit.

  9. 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......, density functional theory calculations, and modeling, we show that the promotion is related to Zn atoms migrating in the Cu surface. The Zn coverage is quantitatively described as a function of the methanol synthesis conditions and of the size-dependent thermodynamic activities of the Cu and Zn...

  10. Low temperature synthesis of carbon encapsulated Fe{sub 7}S{sub 8} nanocrystals as high performance anode for lithium-ion batteries

    Energy Technology Data Exchange (ETDEWEB)

    Liu, Boyang, E-mail: byliu@shmtu.edu.cn; Zhang, Fuhua; Wu, Qianlin; Wang, Junhua; Li, Wenge; Dong, Lihua; Yin, Yansheng

    2015-02-01

    A novel method is developed for low temperature synthesis of carbon encapsulated spherical Fe{sub 7}S{sub 8} nanocrystals with core–shell structure (Fe{sub 7}S{sub 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{sub 7}S{sub 8} nanocrystals with a weight percent of 33.5% have a median size of 25.2 nm. The Fe{sub 7}S{sub 8}@C electrodes retain a reversible capacity of 815 and 539 mAh g{sup −1} after 50 cycles at a current density of 200 and 2284 mA g{sup −1}, respectively. The high capacity, good cycling behavior and rate capability of Fe{sub 7}S{sub 8}@C electrodes are attributed to the good protection and electrical conductivity of carbon shell. - Highlights: • Large scale and low temperature synthesis of Fe{sub 7}S{sub 8}@C with core–shell structure. • The Fe{sub 7}S{sub 8}@C electrodes retain a capacity of 815 mAh g{sup −1} after 50 cycles at 200 mA g{sup −1}. • The Fe{sub 7}S{sub 8}@C electrodes show good cycling behavior and rate capability.

  11. Direct synthesis of large-area continuous ReS2 films on a flexible glass at low temperature

    Science.gov (United States)

    Kim, Youngchan; Kang, Byunggil; Choi, Yongsuk; Cho, Jeong Ho; Lee, Changgu

    2017-06-01

    Rhenium disulfide (ReS2) has been attracting attentions due to the direct bandgap regardless of the thickness and anisotropic electrical, mechanical and optical properties deriving from its unique crystal lattice structure. In order to utilize these properties, some synthesis methods of ReS2 have been studied for electronic applications. However, their results are not suitable for practical applications because of non-uniformity, discontinuity and difficulty of large-area continuous film growth. Here, we report the synthesis method of layer-controlled wafer-scale (7  ×  2 cm2) ReS2 films by chemical vapor deposition with high uniformity and continuity. Especially, we demonstrate successfully a direct synthesis of ReS2 on a transparent flexible glass substrate at low synthesis temperature (450 °C) without the aid of a catalyst or a plasma enhanced system. The field effect transistors with as-grown ReS2 films on the flexible glass exhibit typical n-type behavior with low threshold voltage of 0.75 V, high on-off ratio of ~105, low subthreshold swing of 260 mV/decade and mobility of 0.13 cm2 V-1 S-1. The direct synthesis of ReS2 films on flexible glass will provide the platform to realize large area transfer-free fabrication of high quality transparent flexible electronic devices.

  12. Low temperature synthesis of lead germanate (PbGeO{sub 3})/polypyrrole (PPy) nanocomposites and their lithium storage performance

    Energy Technology Data Exchange (ETDEWEB)

    Feng, Jinkui, E-mail: jinkui@sdu.edu.cn [Key Laboratory for Liquid–Solid Structural Evolution and Processing of Materials (Ministry of Education), School of Materials Science and Engineering, Shandong University, Jinan 250061 (China); Ci, Lijie; Qi, Yongxin; Lun, Ning [Key Laboratory for Liquid–Solid Structural Evolution and Processing of Materials (Ministry of Education), School of Materials Science and Engineering, Shandong University, Jinan 250061 (China); Xiong, Shenglin; Qian, Yitai [School of Chemistry and Chemical Engineering, Shandong University, Jinan 250100 (China)

    2014-09-15

    Highlights: • PbGeO{sub 3}/PPy nanocomposites are successfully fabricated for the first time. • PbGeO{sub 3} nanowire and PbGeO{sub 3}/PPy nanocomposites were characterized as anode materials in lithium ion batteries for the first time. • PPy coating can improve the electrochemical performance of PbGeO{sub 3} by increasing the electronic conductivity and buffering the volume changes during cycling. • The PbGeO{sub 3}/PPy nanocomposites deliver a capacity of 662 mA h g{sup −1} after 50 cycles. - Abstract: PGO/PPy nanocomposites were prepared via a low temperature chemical coating method for the first time. Electrochemical measurements demonstrate that the PbGeO{sub 3} electrodes retain a capacity of 657 mA h g{sup −1} after 100 cycles and possess excellent rate capability indicating that the PGO/PPy nanocomposites could be used as a candidate as high-capacity anode for lithium batteries.

  13. Low temperature synthesis of ZnS and CdZnS shells on CdSe quantum dots.

    Science.gov (United States)

    Zhu, Huiguang; Prakash, Arjun; Benoit, Denise N; Jones, Christopher J; Colvin, Vicki L

    2010-06-25

    Methods for synthesizing quantum dots generally rely on very high temperatures to both nucleate and grow core and core-shell semiconductor nanocrystals. In this work, we generate highly monodisperse ZnS and CdZnS shells on CdSe semiconductor nanocrystals at temperatures as low as 65 degrees C by enhancing the precursor solubility. Relatively small amounts of trioctylphosphine and trioctylphosphine oxide have marked effects on the solubility of the metal salts used to form shells; their inclusion in the precursor solutions, which use thiourea as a sulfur source, can lead to homogeneous and fully dissolved solutions. Upon addition to suspensions of quantum dot cores, these precursors deposit as uniform shells; the lowest temperature for shell growth (65 degrees C) yields the thinnest shells (d quantum yield (QY) of the as-prepared CdSe/ZnS quantum dots ranged from 26% to 46% as compared to 10% for the CdSe cores. This method was further generalized to CdZnS shells by mixing cadmium and zinc acetate precursors. The CdSe/CdZnS nanocrystals have a thicker shell and higher QY (40% versus 36%) as compared to the CdSe/ZnS prepared under similar conditions. These low temperature methods for shell growth are readily amenable to scale-up and can provide a route for economical and less energy intensive production of quantum dots.

  14. Salt-assisted Low Temperature Solid State Synthesis of High Surface Area CoFe2O4 Nanoparticles

    Institute of Scientific and Technical Information of China (English)

    Runhua Qin; Fengsheng Li; Wei Jiang; Li Liu

    2009-01-01

    A novel salt-assisted low temperature solid state method using CoCl2·6H2O, FeCl3·6H2O and NaOH as pre-cursor and using NaCl as a dispersant to synthesize high surface area CoFe2O4 nanoparticles, has been investigated. The effects of the molar ratio of added salt and calcination temperature on the characteristics of the products were investigated by X-ray diffraction (XRD), transmission electron microscopy (TEM), vibrating sample magnetometer (VSM) and Brunauer, Emmett and Teller (BET) surface area analysis. Results showed that the introduction of leachable inert inorganic salt as a hard agglomeration inhibitor in the mixture precursorled to the formation of high dispersive CoFe2O4 nanoparticles; and the increase in specific surface area from 28.28 to 73.97 m2/g, and the saturation magnetization is 84.6 emu/g.

  15. 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%.

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

    Science.gov (United States)

    Estruga, M.; Domingo, C.; Domènech, X.; Ayllón, J. A.

    2009-03-01

    Anatase and rutile biphasic nanostructured titania (TiO2) has been synthesized via hydrolysis of titanium tetraisopropoxide in an aqueous solution of hydrobromic acid (HBr) and N,N-dimethylformamide (DMF) at 80 °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 m2 g-1 and the average pore diameter was 50 Å. 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.

  17. Synthesis of Neodymium-Doped Yttrium Aluminum Garnet (Nd∶YAG) Nano-Sized Powders by Low Temperature Combustion

    Institute of Scientific and Technical Information of China (English)

    Zhang Huashan; Su Chunhui; Han Hui; Hou Zhaoxia

    2005-01-01

    The homogeneously dispersed, less agglomerated (Nd0.01Y0.99)3Al5O12 nano-sized powders were synthesized by the low temperature combustion (LCS), using Nd2O3, Y2O3, Al(NO3)3·9H2O, ammonia water and citric acid as starting materials. This method effectively solves the problems caused by solid-state reaction at high temperature and hard agglomerates brought by the chemical precipitation method. The powders were characterized by TG-DTA, XRD, FT-IR, TEM respectively and the photoluminescence (PL) spectra of (Nd0.01Y0.99)3Al5O12 green and sintered ceramic disks were measured. The results show that the forming temperature of YAG crystal phase is 850 ℃ and YAP crystal phase appearing during the calcinations transforms to pure YAG at 1050 ℃. The particle size of the powders synthesized by the LCS is in a range of 20~50 nm depending on the thermal treatment temperatures. The effectively induced cross section (σin) with the value 4.03×10-19 cm2 of (Nd0.01Y0.99)3Al5O12 ceramics is about 44% higher than that of single crystal.

  18. Porous iron molybdate nanorods: in situ diffusion synthesis and low-temperature H2S gas sensing.

    Science.gov (United States)

    Chen, Yu-Jin; Gao, Xin-Ming; Di, Xin-Peng; Ouyang, Qiu-Yun; Gao, Peng; Qi, Li-Hong; Li, Chun-Yan; Zhu, Chun-Ling

    2013-04-24

    In the paper, we developed an in situ diffusion growth method to fabricate porous Fe2(MoO4)3 nanorods. The average diameter and the length of the porous nanorods were 200 nm and 1.2-4 μm, respectively. Moreover, many micropores existed along axial direction of the Fe2(MoO4)3 nanorods. In terms of nitrogen adsorption-desorption isotherms, calculated pore size was in the range of 4-115 nm, agreeing well with the transmission electron microscope observations. Because of the uniquely porous characteristics and catalytic ability at low temperatures, the porous Fe2(MoO4)3 nanorods exhibited very good H2S sensing properties, including high sensitivity at a low working temperature (80 °C), relatively fast response and recovery times, good selectivity, and long-term stability. Thus, the porous Fe2(MoO4)3 nanorods are very promising for the fabrication of high-performance H2S gas sensors. Furthermore, the strategy presented here could be expended as a general method to synthesize other hollow/porous-type transition metal molybdate nanostructures by rational designation in nanoscale.

  19. 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

  20. A simple solution route to control synthesis of Fe3O4 nanomaterials at low temperature and their magnetic properties

    Institute of Scientific and Technical Information of China (English)

    2009-01-01

    A series of nanostructured iron compounds including cubic Fe3O4 and orthorhombic FeOOH were synthesized via a facile low temperature (in the range of 60-100℃) solution method. In the whole process, the interaction between FeCl2·4H2O and methenamine (C6H12N4) was carried out through a reflux device under different reaction conditions such as temperature, solvent, and duration. The samples were detected by XRD, TEM, SAED, physical property measurement system, and Mssbauer spectroscopy, separately. The experiments showed that magnetic mixture nanoparticles had flake and rod morphologies, and cubic Fe3O4 took on grain nanostructure. Magnetism measurements indicated that the saturated magnetization of the as-obtained magnetic mixture was lower than that of the cubic magnetite. Mssbauer spectroscopy testified the sample consisting of cubic magnetite rather than γ-Fe2O3. In addition, a possible growth mechanism of cubic magnetic nanoparticles under different conditions was discussed.

  1. A simple solution route to control synthesis of Fe304 nanomaterials at low temperature and their magnetic properties

    Institute of Scientific and Technical Information of China (English)

    LIU Yi; CHEN Yun; ZENG YuPing; WANG ShiLong

    2009-01-01

    A series of nanostructured iron compounds including cubic Fe304 and orthorhombic FeOOH were synthesized via a facile low temperature (in the range of 60-100℃) solution method.In the whole process,the interaction between FeCl2.4H2O and methenamine (CeH12N4) was carried out through a reflux device under different reaction conditions such as temperature,solvent,and duration.The samples were detected by XRD,TEM,SAED,physical property measurement system,and M(o)ssbauer spectroscopy,separately.The experiments showed that magnetic mixture nanoparticles had flake and rod morphologies,and cubic Fe304 took on grain nanostructure.Magnetism measurements indicated that the saturated magnetization of the as-obtained magnetic mixture was lower than that of the cubic magnetite.M6ssbauer spectroscopy testified the sample consisting of cubic magnetite rather than y-Fe2O3.In addition,a possible growth mechanism of cubic magnetic nanoparUcles under different conditions was discussed.

  2. Low-temperature synthesis of indium tin oxide nanowires as the transparent electrodes for organic light emitting devices.

    Science.gov (United States)

    Kee, Yeh Yee; Tan, Sek Sean; Yong, Thian Khok; Nee, Chen Hon; Yap, Seong Shan; Tou, Teck Yong; Sáfrán, György; Horváth, Zsolt Endre; Moscatello, Jason P; Yap, Yoke Khin

    2012-01-20

    Low-temperature growth of indium tin oxide (ITO) nanowires (NWs) was obtained on catalyst-free amorphous glass substrates at 250 °C by Nd:YAG pulsed-laser deposition. These ITO NWs have branching morphology as grown in Ar ambient. As suggested by scanning electron microscopy (SEM) and high-resolution transmission electron microscopy (HRTEM), our ITO NWs have the tendency to grow vertically outward from the substrate surface, with the (400) plane parallel to the longitudinal axis of the nanowires. These NWs are low in electrical resistivity (1.6×10⁻⁴ Ω cm) and high in visible transmittance (~90–96%), and were tested as the electrode for organic light emitting devices (OLEDs). An enhanced current density of ~30 mA cm⁻² was detected at bias voltages of ~19–21 V with uniform and bright emission. We found that the Hall mobility of these NWs is 2.2–2.7 times higher than that of ITO film, which can be explained by the reduction of Coulomb scattering loss. These results suggested that ITO nanowires are promising for applications in optoelectronic devices including OLED, touch screen displays, and photovoltaic solar cells.

  3. Low Temperature Hydrothermal Synthesis of Visible-Light-Activated I-Doped TiO2 for Improved Dye Degradation.

    Science.gov (United States)

    Wang, Dongting; Li, Jianwen; Zhou, Guangsheng; Wang, Wenxu; Zhang, Xianxi; Pan, Xu

    2016-06-01

    Iodine doped TiO2 with different iodine/Ti molar ratios has been firstly synthesized with a low temperature hydrothermal route and has been studied systematically in photocatalysis under visible light condition. The resulting iodine doped TiO2 were characterized by X-ray diffraction (XRD), high resolution transmission electron microscopy (TEM), diffuse reflectance spectrum (DRS), and X-ray photoelectron spectroscopy (XPS). The photocatalytic performance investigations were conducted by means of the degradation of Rhodamine B (RhB) under the visible light irradiation in aqueous solution. Under an optimized I/Ti doping ratio of 10 mol%, the photocatalytic performance is greatly better, with degradation efficiency of 95%, which is almost double that of pure TiO2. The superior photocatalytic activity of iodine-doped TiO2 could be mainly attributed to extended visible light absorption originated from the formation of continuous states existed in the band gap of the doped TiO2 introduced by iodine. Active oxygen species, that is, *OH and O2-, were evidenced to be involved in the degradation process and a possible mechanism was also proposed.

  4. A Facile Method for Low-Temperature Synthesis of NaV₃O₈ as Cathode Materials for Lithium Secondary Batteries

    Directory of Open Access Journals (Sweden)

    Chao YUAN

    2011-03-01

    Full Text Available A facile method has been used to synthesize NaV3O8 powders with oxalic acid as the complexing agent. This soft-synthesis technique can effectively reduce the calcination temperature for synthesizing NaV3O8 powders to 300 °C, which is much lower than that in the solid-state synthesis. The thus-synthesized NaV3O8 powders are characterized by XRD, SEM and galvanostatic charge-discharge test. Among the as-prepared powders, the NaV3O8 powder obtained at 350 °C exhibits morphology of porous particles. The electrochemical analysis reveals that this powder demonstrates high discharge capacity and good cycleability.http://dx.doi.org/10.5755/j01.ms.17.1.252

  5. Low Temperature Synthesis of Cubic-phase Fast-ionic Conducting Bi-doped Garnet Solid State Electrolytes

    Science.gov (United States)

    Schwanz, Derek K.; Marinero, Ernesto

    We report on the synthesis of cubic-phase fast ionic conducting garnet solid state electrolytes based on LiLaZrO (LLZO) at unprecedented low synthesis temperatures. Ionic conductivities around 1.2 x 10-4 S/cm are readily achieved. Bismuth aliovalent substitution into LLZO utilizing the Pechini processing method is successfully employed to synthesize LiLaZrBiO compounds. Cubic phase LiLaZrBiO powders are generated in the temperature range 650C to 900C in air. In contrast, in the absence of Bi and under identical synthesis conditions, the cubic phase of LiLaZrO is not formed below 750C and a transformation to the poor ionically conducting tetragonal phase is observed at 800C for the undoped compound. The critical role of Bi in lowering the formation temperature of the garnet cubic phase and the improvements in ionic conductivity are elucidated in this work through microstructural and electrochemical studies.

  6. Low-temperature CVD synthesis of patterned core-shell VO2@ZnO nanotetrapods and enhanced temperature-dependent field-emission properties

    Science.gov (United States)

    Yin, Haihong; Yu, Ke; Song, Changqing; Wang, Zhiliang; Zhu, Ziqiang

    2014-09-01

    VO2 nanostructures are attractive materials because of their reversible metal-insulator transition (MIT) and wide applications in devices. When they are used as field emitters, a new type of temperature-controlled field emission device can be fabricated. Vapor transport methods used to synthesize traditional VO2 nanostructures are energy-intensive, low yield, and produce simple morphology (quasi-1D) that exhibits substrate clamping; thus they are not suitable for field emission applications. To overcome these limitations, ZnO nanotetrapods were used as templates, and patterned core-shell VO2@ZnO nanotetrapods were successfully grown on an ITO/glass substrate via a low-temperature CVD synthesis. SEM, TEM, EDX, XPS analyses and X-ray diffraction revealed that the cores and shells of these nanotetrapods were single crystal wurtzite-type ZnO and polycrystalline VO2, respectively. The VO2@ZnO nanotetrapods show strongly MIT-related FE properties, the emission current density at low temperature is significantly enhanced in comparison with pure VO2 nanostructures, and the emission current density increased by about 20 times as the ambient temperature increased from 25 to 105 °C at a fixed field of 5 V μm-1. Although the VO2@ZnO nanotetrapods show a worse FE performance at low temperatures compared with pure ZnO nanotetrapods, the FE performance was substantially improved at high temperatures, which was attributed to the MIT-related band bending near the interface and the abrupt resistance change across the MIT.

  7. Synthesis of High Surface Area and Well Crystallized Mesoporous WC at Low Temperature with a Pore Structure Collapsed Replication Route

    Institute of Scientific and Technical Information of China (English)

    LI Hua; SHI Jianlin; CHEN Hangrong; ZHANG Lingxia; LI Lei

    2011-01-01

    An approach named "pore structure collapsed replication route" has been developed to prepare mesoporous WC materials with a high surface area (105 m2/g) and crystallized framework at a temperature as low as 700 ℃. The XRD, TEM, EDS, and BET characterizations were conducted to analyze the effects of the synthesis parameters and the template types on the structure of mesoporous WC. The compaction on the templates is the key to form mesoporous structure of WC while the templates help to control the size of crystalline. At a content of 7 wt% for the precursor of WC, the mesoporous WC could be formed with well ordered structure.

  8. 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.

  9. Low temperature induces oocytes p34cdc2 synthesis and accumulation—the acquisition of competence to resume meiosis in toad oocytes

    Institute of Scientific and Technical Information of China (English)

    LUJINING; ZHENGGU; 等

    1996-01-01

    Full grown oocytes derived from Bufo Bufo gargarizans rearing at high temperature environment (24℃), never underwent GVBD after progesterone treatment.No p34cdc2 Hl kinase activity was detected in the oocytes after progesterone stimulation or OA microinjection;Western blotting analysis showed that the level of p34cdc2 and p33 in the oocytes are significantly lower than those in the oocytes derived from the hibernating toads (below 10℃).35S-Met incorporation analysis showed that when the oocytes were incubated at 6℃,synthesis of about thirty defferent polypeptides was promoted or induced,including p34cdc2 and some other p13suc1-binding proteins.All these results indicated that a low temperature environment is essential for the oocytes of Bufo Bufo gargarizans to express and stord some cell cycle drivers and its regulators,and to gain the maturation competence.These results will also provide a nwe clue for explaining the molecular mechanisms why gametogenesis of some organisms depends on a relative low temperature and how to maintain the geographical distribution of some animals.

  10. Carbon gel assisted low temperature liquid-phase synthesis of C-LiFePO4/graphene layers with high rate and cycle performances

    Science.gov (United States)

    Tang, Hongwei; Si, Yanli; Chang, Kun; Fu, Xiaoning; li, Bao; Shangguan, Enbo; Chang, Zhaorong; Yuan, Xiao-Zi; Wang, Haijiang

    2015-11-01

    Nano-scale LiFePO4/graphene oxide (GO) as cathode materials for lithium ion batteries has been successfully synthesized via a one-step carbon gel assisted liquid-phase approach at a low-temperature (108 °C) and normal pressure. C-LiFePO4/graphene layers (G) composites, composed of LiFePO4, amorphous carbon and graphene layers, are then produced after rapid high temperature carbon treatment. Interface tunnel effect, produced by the intimate contact of LiFePO4 particles with amorphous carbon and graphene layers, greatly improves the properties of the composites. Electrochemical tests indicate that the optimal amount of GO addition is 1 wt.% in terms of achieving a high electrochemical performance of the C-LiFePO4/G composites. Discharge capacity of the C-LiFePO4/G composites is 160.0 mAh g-1 at 0.2 C. When the current rate is further increased to 60 C, the discharge capacity of C-LiFePO4/G can reach 68 mAh g-1. At a high current rate of 20 C, the capacity attenuation rate of the C-LiFePO4/G electrode is only 9.6% after 200 cycles, showing excellent high-rate discharge capability and cycle performance. This is achieved under a facile synthesis condition of a simple procedure, low temperature, and normal pressure.

  11. Influences of guide-tube and bluff-body on advanced atmospheric pressure plasma source for single-crystalline polymer nanoparticle synthesis at low temperature

    Science.gov (United States)

    Kim, Dong Ha; Park, Choon-Sang; Kim, Won Hyun; Shin, Bhum Jae; Hong, Jung Goo; Park, Tae Seon; Seo, Jeong Hyun; Tae, Heung-Sik

    2017-02-01

    The use of a guide-tube and bluff-body with an advanced atmospheric pressure plasma source is investigated for the low-temperature synthesis of single-crystalline high-density plasma polymerized pyrrole (pPPy) nano-materials on glass and flexible substrates. Three process parameters, including the position of the bluff-body, Ar gas flow rate, and remoteness of the substrate from the intense and broadened plasma, are varied and examined in detail. Plus, for an in-depth understanding of the flow structure development with the guide-tube and bluff-body, various numerical simulations are also conducted using the same geometric conditions as the experiments. As a result, depending on both the position of the bluff-body and the Ar gas flow rate, an intense and broadened plasma as a glow-like discharge was produced in a large area. The production of the glow-like discharge played a significant role in increasing the plasma energy required for full cracking of the monomers in the nucleation region. Furthermore, a remote growth condition was another critical process parameter for minimizing the etching and thermal damage during the plasma polymerization, resulting in single- and poly-crystalline pPPy nanoparticles at a low temperature with the proposed atmospheric pressure plasma jet device.

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

    Energy Technology Data Exchange (ETDEWEB)

    Terzano, Roberto [Dipartimento di Biologia e Chimica Agro-forestale ed Ambientale, Universita degli Studi di Bari, Via Amendola 165/A, I-70126 Bari (Italy)]. E-mail: r.terzano@agr.uniba.it; Spagnuolo, Matteo [Dipartimento di Biologia e Chimica Agro-forestale ed Ambientale, Universita degli Studi di Bari, Via Amendola 165/A, I-70126 Bari (Italy); Medici, Luca [Istituto di Metodologie per l' Analisi Ambientale (I.M.A.A.), C.N.R, Contrada S. Loja, I-85050 Tito Scalo, Potenza (Italy); Tateo, Fabio [Istituto di Geoscienze e Georisorse (I.G.G.), C.N.R., Sezione di Padova, c/o Dipartimento di Geologia, Paleontologia e Geofisica, Universita degli Studi di Padova, Via Giotto 1, I-35137 Padova (Italy); Vekemans, Bart [Department of Chemistry, University of Antwerp, Universiteitsplein 1, B-2610, Wilrijk (Belgium); Janssens, Koen [Department of Chemistry, University of Antwerp, Universiteitsplein 1, B-2610, Wilrijk (Belgium); Ruggiero, Pacifico [Dipartimento di Biologia e Chimica Agro-forestale ed Ambientale, Universita degli Studi di Bari, Via Amendola 165/A, I-70126 Bari (Italy)

    2006-06-15

    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{sup -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 ({mu}-XANES) and extended X-ray absorption fine structure ({mu}-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.

  13. Facile, low temperature synthesis of SnO2/reduced graphene oxide nanocomposite as anode material for lithium-ion batteries

    Science.gov (United States)

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

    2017-08-01

    We demonstrate a facile, single step, low temperature and energy efficient strategy for the synthesis of SnO2-reduced graphene oxide (RGO) nanocomposite where the crystallization of SnO2 nanoparticles and the reduction of graphene oxide takes place simultaneously by an in situ chemical reduction process. The electrochemical property of the SnO2-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 SnO2 nanoparticle aggregation and degrade the Li ion storage property.

  14. Sm1.5Sr0.5MO4 (M=Ni,Co,Fe) Cathode Catalysts for Ammonia Synthesis at Atmospheric Pressure and Low Temperature

    Institute of Scientific and Technical Information of China (English)

    XU,Gaochao; LIU,Ruiquan

    2009-01-01

    Sm1.5Sr0.5MO4 (M=Ni,Co,Fe) (SSM) catalysts were prepared by a sol-gel method and characterized by X-ray diffraction (XRD) and scanning electron microscopy (SEM).Ammonia was synthesized from wet hydrogen and dry nitrogen at atmospheric pressure and low temperature (25-100 ℃) with applied voltage,using SSM as a cathode,Ni-Ce0.5Sm0.2O2-δ(Ni-SDC) as an anode,and silver-platinum film as a current collector,Nation proton exchange membrane as a proton permeating membrane.Several important factors on ammonia synthesis were investigated and the optimal synthetic temperature was found,at which the highest rate of evolution of ammonia was up to 1.05×10-8 mol·cm- 2·S-1.

  15. Low temperature synthesis of layered NaxCoO2 and KxCoO2 from NaOH/KOH fluxes and their ion exchange properties

    Indian Academy of Sciences (India)

    C Shivakumara; M S Hegde

    2003-10-01

    We report a low temperature synthesis of layered Na0.20CoO2 and K0.44CoO2 phases from NaOH and KOH fluxes at 400°C. These layered oxides are employed to prepare hexagonal HCoO2, LiCoO2 and Delafossite AgCoO2 phases by ion exchange method. The resulting oxides were characterised by powder X-ray diffraction, X-ray photoelectron spectroscopy, SEM and EDX analysis. Final compositions of all these oxides are obtained from chemical analysis of elements present. Na0.20CoO2 oxide exhibits insulating to metal like behaviour, whereas AgCoO2 is semiconducting.

  16. Rapid automated materials synthesis instrument: exploring the composition and heat-treatment of nanoprecursors toward low temperature red phosphors.

    Science.gov (United States)

    Lin, Tian; Kellici, Suela; Gong, Kenan; Thompson, Kathryn; Evans, Julian R G; Wang, Xue; Darr, Jawwad A

    2010-05-10

    We report on the commissioning experimental run of the rapid automated materials synthesis instrument (RAMSI), a combinatorial robot designed to manufacture, clean, and print libraries of nanocrystal precursor solid compositions. The first stage of RAMSI, parallel synthesis, uses a fully automated high throughput continuous hydrothermal (HiTCH) flow reactor for automatic metal salt precursor mixing, hydrothermal flow reaction, and sample slurry collection. The second stage of RAMSI provides integrated automated cleanup, and the third section is a ceramic printing function. Nanocrystal precursor solid ceramics were synthesized from precursor solutions and collected into 50 mL centrifuge tubes where they were cleaned by multiple centrifugation and redispersion cycles (monitored by intelligent scanning turbidimetry) and printed with an automated pipette. Eight unique compositions of a model phosphor library comprising pure nano-Y(OH)(3) and Eu(3+) doped-yttrium hydroxide, Y(OH)(3):Eu(3+) nanocrystal precursor solid were synthesized (with 2 centrifuge tubes' worth collected per composition), processed, and printed in duplicate as 75, 100, and 125 microL dots in a 21.6 ks (6 h) experiment (note: the actual time for synthesis of each sample tube was only 12 min so up to 60 compositions could easily be synthesized in 12 h if one centrifuge tube per composition was collected instead). The Y(OH)(3):Eu(3+) samples were manually placed in a furnace and heat-treated in air for 14.4 ks (4 h) in the temperature range 200-1200 at 100 degrees C intervals (giving a total of 84 samples plus one as-prepared pure Y(OH)(3) sample). The as-prepared and heat-treated ceramic samples were affixed to 4 mm wide hemispherical wells in a custom-made aluminum well-plate and analyzed using a fluorescence spectrometer. When the library was illuminated with a 254 nm light source (and digitally imaged and analyzed), the 3 mol % Eu(3+) sample heat-treated at 1200 degrees C gave the most intense

  17. 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.

  18. Low temperature synthesis of Ba1–SrSnO3 ( = 0–1) from molten alkali hydroxide flux

    Indian Academy of Sciences (India)

    B Ramdas; R Vijayaraghavan

    2010-02-01

    Perovskite structured stannates (Ba1–SrSnO3, = 0.0–1.0) powders have been synthesized for the first time by molten salt synthesis (MSS) method using KOH as the flux at lower temperature (400°C) compared to other methods. The phase formation was confirmed by FT–IR spectroscopy, powder X-ray diffraction (XRD) and the microstructure was analysed by scanning electron microscopy. XRD patterns reveal the formation of single phasic products for parent and substituted products with good crystallinity throughout the range ( = 0.0–1.0). The morphology of the particles of BaSnO3 and SrSnO3 is spherical and rod shaped, respectively. Effect of soaking periods on the grain growth is observed clearly in SrSnO3. Ba0.5Sr0.5SnO3 (BSS5) crystallizes in flake like morphology.

  19. 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.

  20. Breaking scaling relations to achieve low-temperature ammonia synthesis through LiH-mediated nitrogen transfer and hydrogenation

    Science.gov (United States)

    Wang, Peikun; Chang, Fei; Gao, Wenbo; Guo, Jianping; Wu, Guotao; He, Teng; Chen, Ping

    2017-01-01

    Ammonia synthesis under mild conditions is a goal that has been long sought after. Previous investigations have shown that adsorption and transition-state energies of intermediates in this process on transition metals (TMs) scale with each other. This prevents the independent optimization of these energies that would result in the ideal catalyst: one that activates reactants well, but binds intermediates relatively weakly. Here we demonstrate that these scaling relations can be broken by intervening in the TM-mediated catalysis with a second catalytic site, LiH. The negatively charged hydrogen atoms of LiH act as strong reducing agents, which remove activated nitrogen atoms from the TM or its nitride (TMN), and as an immediate source of hydrogen, which binds nitrogen atoms to form LiNH2. LiNH2 further splits H2 heterolytically to give off NH3 and regenerate LiH. This synergy between TM (or TMN) and LiH creates a favourable pathway that allows both early and late 3d TM-LiH composites to exhibit unprecedented lower-temperature catalytic activities.

  1. Selective anaerobic oxidation of methane enables direct synthesis of methanol.

    Science.gov (United States)

    Sushkevich, Vitaly L; Palagin, Dennis; Ranocchiari, Marco; van Bokhoven, Jeroen A

    2017-05-05

    Direct functionalization of methane in natural gas remains a key challenge. We present a direct stepwise method for converting methane into methanol with high selectivity (~97%) over a copper-containing zeolite, based on partial oxidation with water. The activation in helium at 673 kelvin (K), followed by consecutive catalyst exposures to 7 bars of methane and then water at 473 K, consistently produced 0.204 mole of CH3OH per mole of copper in zeolite. Isotopic labeling confirmed water as the source of oxygen to regenerate the zeolite active centers and renders methanol desorption energetically favorable. On the basis of in situ x-ray absorption spectroscopy, infrared spectroscopy, and density functional theory calculations, we propose a mechanism involving methane oxidation at Cu(II) oxide active centers, followed by Cu(I) reoxidation by water with concurrent formation of hydrogen. Copyright © 2017, American Association for the Advancement of Science.

  2. Comparison of two-phase and three-phase methanol synthesis processes

    NARCIS (Netherlands)

    van de Graaf, G.H; Beenackers, A.A C M

    1996-01-01

    A comparison is made between the ICI (two-phase) methanol synthesis process and a three-phase slurry process based on a multi-stage agitated reactor. The process calculations are based on a complete reactor system consisting of the reactor itself, a recycling system and a gas-liquid separator. The b

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

    NARCIS (Netherlands)

    van den Berg, Roy|info:eu-repo/dai/nl/358212049; Parmentier, Tanja E.; Elkjaer, Christian F.; Gommes, Cedric J.; Sehested, Jens; Helveg, Stig; de Jongh, Petra E.|info:eu-repo/dai/nl/186125372; de Jong, Krijn P.|info:eu-repo/dai/nl/06885580X

    2015-01-01

    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 func

  4. Modeling and Experimental Studies on Phase and Chemical Equilibria in High-Pressure Methanol Synthesis

    NARCIS (Netherlands)

    van Bennekom, Joost G.; Winkelman, Jozef G. M.; Venderbosch, Robertus H.; Nieland, Sebastiaan D. G. B.; Heeres, Hero J.

    2012-01-01

    A solution method was developed to calculate the simultaneous phase and chemical equilibria in high-pressure methanol synthesis (P = 20 MPa, 463

  5. 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,

  6. Comparison of two-phase and three-phase methanol synthesis processes

    NARCIS (Netherlands)

    van de Graaf, G.H; Beenackers, A.A C M

    1996-01-01

    A comparison is made between the ICI (two-phase) methanol synthesis process and a three-phase slurry process based on a multi-stage agitated reactor. The process calculations are based on a complete reactor system consisting of the reactor itself, a recycling system and a gas-liquid separator. The

  7. Structure sensitivity of Cu and CuZn catalysts relevant to industrial methanol synthesis

    NARCIS (Netherlands)

    Berg, Roy van den|info:eu-repo/dai/nl/358212049; Prieto Gonzalez, Gonzalo|info:eu-repo/dai/nl/328231703; Korpershoek, Gerda; van der Wal, L.I.; Bunningen, Arnoldus J. van; Lægsgaard-Jørgensen, Susanne; Jongh, P. E. de|info:eu-repo/dai/nl/186125372; de Jong, K.P.|info:eu-repo/dai/nl/06885580X

    2016-01-01

    For decades it has been debated whether the conversion of synthesis gas to methanol over copper catalysts is sensitive or insensitive to the structure of the copper surface. Here we have systematically investigated the effect of the copper particle size in the range where changes in surface structur

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

    NARCIS (Netherlands)

    van den Berg, Roy|info:eu-repo/dai/nl/358212049; Parmentier, Tanja E.; Elkjaer, Christian F.; Gommes, Cedric J.; Sehested, Jens; Helveg, Stig; de Jongh, Petra E.|info:eu-repo/dai/nl/186125372; de Jong, Krijn P.|info:eu-repo/dai/nl/06885580X

    2015-01-01

    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 func

  9. 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...

  10. The role of arsine in the deactivation of methanol synthesis catalysts

    Energy Technology Data Exchange (ETDEWEB)

    Quinn, R.; Mebrahtu, T.; Dahl, T.A.; Lucrezi, F.A.; Toseland, B.A. [Air Products and Chemicals Inc., Adsorption Technology Center, 7201 Hamilton Boulevard, Allentown, PA 18195-1501 (United States)

    2004-06-18

    The liquid phase methanol (LPMEOH) process is successfully producing methanol from coal-derived synthesis gas on an industrial scale. This process uses a standard copper, zinc oxide, and alumina catalyst suspended in an inert mineral oil in a slurry bubble column reactor. An arsenic-containing species, most reasonably arsine, was found in the feed to the LPMEOH commercial demonstration facility located at Eastman Chemical Company's chemicals-from-coal complex in Kingsport, TN. Laboratory testing showed that arsine is, in fact, a powerful methanol synthesis catalyst poison. At levels as low as 150ppbv, arsine results in a rapid deactivation of the catalyst. Removal of arsine results in a deactivation rate consistent with a clean synthesis gas feed; that is, arsine poisoning stops when it is removed from the feed. We infer that arsine reacts irreversibly with the catalyst under the methanol synthesis conditions. X-ray absorption spectroscopy (XAS) of arsenic-containing used catalyst indicated the presence of zero-valent arsenic in an intermetallic surface phase that is structurally related to Domeykite (Cu{sub 3}As). Experimental evidence, thermodynamics, and literature relating to other metal-arsine chemistry were consistent with dissociative adsorption of arsine on the copper surface to form gaseous H{sub 2} and Cu{sub 3}As. To deal with arsine poisoning, we have developed adsorption technology that can remove arsine to levels low enough that catalyst performance is unaffected.

  11. Low temperature synthesis of boron carbide micropowder%碳化硼微粉的低温合成

    Institute of Scientific and Technical Information of China (English)

    张云霏; 仲剑初; 王洪志

    2011-01-01

    以聚乙烯醇和硼酸为原料,首先合成聚乙烯醇硼酸酯前驱物凝胶,然后将前驱物热解及碳热还原制备碳化硼粉末.考察了聚乙烯醇与硼酸的物质的量比,前驱物热解温度,碳热还原温度以及还原时间等因素对碳化硼合成的影响.采用IR、化学分析、XRD、离心粒度分析、SEM等方法对中间物及产物进行了表征,确定了中间物及产物的组成、物相、粒度分布及形貌.研究结果表明:前驱物合成的适宜原料配比是n(聚乙烯醇)∶n(硼酸)=4∶1;前驱物在600℃下热解2h,在1 300℃下碳热还原2h,得到粒径为10 μm左右的碳化硼微粉.%Polyvinyl borate gel was prepared with polyvinyl alcohol (PVA) and boron acid as raw materials, which was employed as precursor for preparing boron carbide and then it was pyrolyzed and reduced to form boron carbide powder by carbonthermal process. Effects of amount-of-substance ratio of polyvinyl alcohol to boron acid, pyrolyzed temperature of the precursor, carbonthermal reduction temperature,and reduction time of pyrolyzed precursor on boron carbide synthesis were respectively investigated. Intermediate and product were respectively characterized by FT-IR,chemical composition,XRD, SEM, and particle size analysis etc.. Results indicated that the optimum raw material mix ratio for precursor polyvinyl borate was n[ PVA) : n( boron acid) =4: 1 ;B4C powder with a primary particle size of 10 ftm could be obtained when the precursor was pyrolyzed at 600 °C for 2 h,and then treated at 1300 ℃ for 2 h.

  12. Confined-space synthesis of single crystal TiO2 nanowires in atmospheric vessel at low temperature: a generalized approach

    Science.gov (United States)

    Wang, Xiaoyue; Wang, Hai; Zhou, Yu; Liu, Yong; Li, Baojun; Zhou, Xiang; Shen, Hui

    2015-01-01

    Extensive efforts have been devoted to develop innovative synthesis strategies for nanomaterials in order to exploit the true potential of nanotechnology. However, most approaches require high temperature or high pressure to favor crystallization. Here we highlight an unconventional approach for the confined-space synthesis of the single crystal TiO2 nanowires in the atmospheric vessel at low temperature by cleverly manipulating the unique physical properties of straight-chain saturated fatty acids. Our method also applys to icosane due to its straight-chain saturated hydrocarbon structure and similar physical properties to the saturated fatty acids. Interestingly, we also found that the unsaturated fatty acids can facilitate the crystal growth, but their bent chains lead to the formation of TiO2 particle aggregates. In addition, we demonstrate the growth of TiO2 nanowires on arbitrary substrates, which are of great importance for their wider applications. We thus anticipate our presented method to be a possible starting point for non-classical crystallization strategies and be easily adapted for the fabrication of all other inorganic materials.

  13. 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)

  14. Low temperature asphalt mixtures

    OpenAIRE

    Modrijan, Damjan

    2006-01-01

    This thesis presents the problem of manufacturing and building in the asphalt mixtures produced by the classical hot procedure and the possibility of manufacturing low temperature asphalt mixtures.We will see the main advantages of low temperature asphalt mixtures prepared with bitumen with organic addition Sasobit and compare it to the classical asphalt mixtures. The advantages and disadvantages of that are valued in the practical example in the conclusion.

  15. Low temperature creep plasticity

    Directory of Open Access Journals (Sweden)

    Michael E. Kassner

    2014-07-01

    Full Text Available The creep behavior of crystalline materials at low temperatures (T < 0.3Tm is discussed. In particular, the phenomenological relationships that describe primary creep are reviewed and analyzed. A discussion of the activation energy for creep at T < 0.3Tm is discussed in terms of the context of higher temperature activation energy. The basic mechanism(s of low temperature creep plasticity are discussed, as well.

  16. Microstructural characterization of Cu/ZnO/Al2O3 catalysts for the synthesis and steam reforming of methanol

    OpenAIRE

    2008-01-01

    Cu/ZnO/Al2O3 catalysts represent a versatile catalyst system for methanol chemistry, including the synthesis and steam reforming of methanol. Formally, the steam reforming of methanol is the reverse of methanol synthesis from CO2 and H2. In the present work a set of differently prepared Cu/ZnO/Al2O3 catalysts with a fixed composition of Cu/Zn/Al = 60:30:10 were investigated by in situ bulk techniques, X-ray diffraction, and X-ray absorption spectroscopy. Additionally, microscopic and morpholo...

  17. Critical temperatures and pressures of reacting mixture in synthesis of dimethyl carbonate with methanol and carbon dioxide

    Institute of Scientific and Technical Information of China (English)

    Xing Cui Guo; Zhang Feng Qin; Guo Fu Wang; Jian Guo Wang

    2008-01-01

    Critical temperatures and pressures of nominal reacting mixture in synthesis of dimethyl carbonate (DMC)from methanol and carbon dioxide(quaternary mixture of carbon dioxide+methanol+water+DMC)were measured using a high-pressure view cell.The results suggested that the critical properties of the reacting mixture depended on the reaction extent as well as its initial composition(initial ratio of carbon dioxide to methanol).Such information is essential for determining the reaction conditions when one intends to carry out the synthesis of DMC with CO2 and methanol under supercritical conditions.

  18. Mechanochemical Synthesis of Mo-Cu Nanocomposites Powders at Low Temperature%低温机械化学法制备Mo-Cu纳米复合粉末

    Institute of Scientific and Technical Information of China (English)

    孙翱魁; 王德志; 李翼

    2012-01-01

    Low temperature synthesis of Mo-Cu composite powders was conducted by mechanochemical treatment (hall-milling) of CuMoO4 and MoO3 mixtures followed by subsequent coreduction process. The preparation temperature of the precursors (CuMoO4-MoO3 mixtures), phases and microstructures of the Mo-Cu composites were investigated by differential scanning calorimeter (DSC), X-ray diffractometer (XRD), scanning electron microscope (SEM) and transmission electron microscope (TEM), respectively. The thermodynamical conditions at different stages of hydrogen reduction of Mo-Cu nanocotnposite powders were analyzed. Results show that the mechanochemical treatment (ball-milling) can significantly enhance the reduction activity by rbducing the particle sizes of powders and hence increasing the reaction surface area, therefore giving rise to the synthesis of Mo-Cu composite powders at relatively low temperature (680 ℃). By optimizing the experimental parameters, Mo-25 wt% Cu nanocomposite powders with superfine particles ranging from 50 to 100 nmcanbe obtained by ball-milling for 15 h followed by reduction in hydrogen at 680 ℃.%以CuMoO4-MoO3粉末为前驱体,采用机械化学-氢气共还原的方法制备出Mo-Cu纳米复合粉末.通过DSC对前躯体的制备温度进行研究,通过XRD、SEM及TEM分别对粉末的相组成、形貌和粒度进行表征,从热力学的角度对粉末的还原过程进行分析.结果表明,机械球磨可以有效地降低粉末的颗粒尺寸,增大反应面积,提高粉末还原活性,从而在低温下制备出Mo-Cu复合粉末.通过优化工艺参数,对机械球磨15h的CuMoO4-MoO3混合粉末在680℃下还原,可以得到颗粒尺寸为50~100 nm的Mo-25%Cu (质量分数)纳米复合粉末.

  19. Synthesis of Dimethyl Carbonate from Methanol and Carbon Dioxide Catalyzed by Potassium Hydroxide under Mild Conditions

    Institute of Scientific and Technical Information of China (English)

    2005-01-01

    The synthesis of dimethyl carbonate (DMC) from methanol and carbon dioxide using potassium hydroxide as catalyst in the presence of CH3I and the effect of ionic liquid on the reaction were investigated. The results showed that KOH is an effective catalyst; the high selectivity and raised yield of DMC formation under mild conditions were achieved. However,the addition of the ionic liquid, 1-ethyl-3-methylimidazolium bromide (emimBr), can evidently accelerate the conversion of methanol and yield of the product.

  20. Low-temperature growth of multi-walled carbon nanotubes by thermal CVD

    Energy Technology Data Exchange (ETDEWEB)

    Halonen, Niina; Leino, Anne-Riikka; Maeklin, Jani; Kukkola, Jarmo; Toth, Geza [Microelectronics and Materials Physics Laboratories, University of Oulu (Finland); Sapi, Andras; Nagy, Laszlo; Puskas, Robert; Kukovecz, Akos; Konya, Zoltan [Department of Applied and Environmental Chemistry, University of Szeged (Hungary); Wu, Ming-Chung; Liao, Hsueh-Chung; Su, Wei-Fang [Department of Materials Science and Engineering, National Taiwan University, Taipei (China); Shchukarev, Andrey; Mikkola, Jyri-Pekka [Department of Chemistry, Institute of Technical Chemistry, Chemical-Biological Center, Umeaa University (Sweden); Kordas, Krisztian [Microelectronics and Materials Physics Laboratories, University of Oulu (Finland); Department of Chemistry, Institute of Technical Chemistry, Chemical-Biological Center, Umeaa University (Sweden)

    2011-11-15

    Low-temperature thermal chemical vapor deposition (thermal CVD) synthesis of multi-walled carbon nanotubes (MWCNTs) was studied using a large variety of different precursor compounds. Cyclopentene oxide, tetrahydrofuran, methanol, and xylene:methanol mixture as oxygen containing heteroatomic precursors, while xylene and acetylene as conventional hydrocarbon feedstocks were applied in the experiments. The catalytic activity of Co, Fe, Ni, and their bi- as well as tri-metallic combinations were tested for the reactions. Low-temperature CNT growth occurred at 400 C when using bi-metallic Co-Fe and tri-metallic Ni-Co-Fe catalyst (on alumina) and methanol or acetylene as precursors. In the case of monometallic catalyst nanoparticles, only Co (both on alumina and on silica) was found to be active in the low temperature growth (below 500 C) from oxygenates such as cyclopentene oxide and methanol. The structure and composition of the achieved MWCNTs products were studied by scanning and transmission electron microscopy (SEM and TEM) as well as by Raman and X-ray photoelectron spectroscopy (XPS) and by X-ray diffraction (XRD). The successful MWCNT growth below 500 C is promising from the point of view of integrating MWCNT materials into existing IC fabrication technologies. (Copyright copyright 2011 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  1. Low-temperature synthesis of SmFeAsO0.7F0.3 - δ wires with a high transport critical current density

    Science.gov (United States)

    Wang, Lei; Qi, Yanpeng; Wang, Dongliang; Gao, Zhaoshun; Zhang, Xianping; Zhang, Zhiyu; Wang, Chunlei; Ma, Yanwei

    2010-07-01

    Ag-sheathed SmFeAsO0.7F0.3 - δ (Sm-1111) superconducting wires were prepared by a one-step solid state reaction at temperatures as low as 850-900 °C, instead of commonly used temperatures of 1150-1250 °C. The x-ray diffraction pattern of the as-sintered samples is well indexed on the basis of the tetragonal ZrCuSiAs-type structure. We characterized the transport critical current density Jc of the SmFeAsO0.7F0.3 - δ wires in increasing and subsequently decreasing fields, by a resistive four-probe method. A transport Jc as high as ~ 1300 A cm - 2 at 4.2 K and self-field has been observed for the first time in Sm-1111 type polycrystalline superconductors. The Jc also shows a rapid depression in small applied fields as well as a magnetic-history dependence, indicating weak-linked grain boundaries. The low-temperature synthesis method can be very beneficial for fabricating the RE-1111 iron oxypnictides in a convenient and safe way.

  2. 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.

  3. Easy-to-operate and low-temperature synthesis of gram-scale nitrogen-doped graphene and its application as cathode catalyst in microbial fuel cells.

    Science.gov (United States)

    Feng, Leiyu; Chen, Yinguang; Chen, Lang

    2011-12-27

    Nitrogen-doped graphene (NG), with unique electronic properties, is showing great promise for a wide range of practical applications. However, the reported approaches for NG synthesis are usually complex, require high temperatures, produce lower atomic ratios of nitrogen to carbon (N/C), and do not deliver products in a reasonably large quantity. Here we report an easy-to-operate and low-temperature method to synthesize NG in gram-scale quantities with a denotation process. High-resolution transmission electron microscopy, Raman spectroscopy, and X-ray diffraction characterization suggested that the synthesized NG films were uniformly multilayered and had a high crystalline quality. In the graphene sheets the existence of nitrogen substitution with an atomic ratio of N/C 12.5%, which was greater than those reported in the literature, was confirmed by X-ray photoelectron spectroscopic analysis. In the neutral phosphate buffer solution, the synthesized NG was demonstrated to act as a metal-free electrode with excellent electrocatalytic activity and long-term operation stability for oxygen reduction via a combination of two-electron and four-electron pathways. When the NG was applied as the cathode catalyst of microbial fuel cells (MFCs), the obtained maximum power density was comparable to that of conventional platinum catalyst. More importantly, MFCs with NG produced power more stably and less expensively than those with Pt catalyst, indicating that the synthesized NG might be used as a good alternative to Pt catalyst in MFCs with a long run.

  4. Stereospecific growth of densely populated rutile mesoporous TiO{sub 2} nanoplate films: a facile low temperature chemical synthesis approach

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Go-Woon; Cho, Young-Jin; Mane, Rajaram S; Shashikala, V; Yadav, Jyotiprakash; Gaikwad, Rajendra S; Jung, Kwang-Deog; Joo, Oh-Shim [Clean Energy Research Center, Korea Institute of Science and Technology, Seoul 130-650 (Korea, Republic of); Ambade, Swapnil B; Lee, Soo-Hyoung [School of Semiconductor and Chemical Engineering, Nanomaterials Processing Research Center, Chonbuk National University, Jeonju (Korea, Republic of); Han, Sung-Hwan, E-mail: shlee66@jbnu.ac.kr, E-mail: joocat@kist.re.kr [Inorganic Nanomaterials Laboratory, Chemistry Department, Hanyang University, Seoul (Korea, Republic of)

    2010-03-12

    We report for the first time, using a simple and environmentally benign chemical method, the low temperature synthesis of densely populated upright-standing rutile TiO{sub 2} nanoplate films onto a glass substrate from a mixture of titanium trichloride, hydrogen peroxide and thiourea in triply distilled water. The rutile TiO{sub 2} nanoplate films (the phase is confirmed from x-ray diffraction analysis, selected area electron diffraction, energy-dispersive x-ray analysis, and Raman shift) are 20-35 nm wide and 100-120 nm long. The chemical reaction kinetics for the growth of these upright-standing TiO{sub 2} nanoplate films is also interpreted. Films of TiO{sub 2} nanoplates are optically transparent in the visible region with a sharp absorption edge close to 350 nm, confirming an indirect band gap energy of 3.12 eV. The Brunauer-Emmet-Teller surface area, Barret-Joyner-Halenda pore volume and pore diameter, obtained from N{sub 2} physisorption studies, are 82 m{sup 2} g{sup -1}, 0.0964 cm{sup 3} g{sup -1} and 3.5 nm, respectively, confirming the mesoporosity of scratched rutile TiO{sub 2} nanoplate powder that would be ideal for the direct fabrication of nanoscaled devices including upcoming dye-sensitized solar cells and gas sensors.

  5. 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.

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

    Science.gov (United States)

    Alnoor, Hatim; Chey, Chan Oeurn; Pozina, Galia; Liu, Xianjie; Khranovskyy, Volodymyr; Willander, Magnus; Nur, Omer

    2015-08-01

    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.

  7. 低温液相合成Engel复盐晶体研究%Low Temperature Liquid Synthesis of Engel Double Salt Crystal

    Institute of Scientific and Technical Information of China (English)

    张文辉; 张茜; 谷守玉; 万亚珍

    2013-01-01

    It was of great importance in plotting the phase diagram of the Engel double salt crystal for the aim to control the production process.The best conditions of synthesis Engel double salt by low temperature liquid synthesis method were studied.The results shown the basic magnesium carbonate was putting the saturated solution of potassium bicarbonate according to the ratio as following; potassium bicarbonate; basic magnesium carbonate ( wt.) = 39.0: 0.2 and then reacted under the hydrothermal condition as 40 ℃ for 10 min, the mixture solution was crystallized rapidly cooling down to 25℃ and water-bathed for 7 h for the crystal growth process , the Engel double salt crystal were synthesized.The crystal was tested by X-ray powder diffraction ( XRD), which proved that it was in agreeing with the standard spectra.The result showed that the crystal's morphology was of good crystallization.%Engel复盐晶体合成对于准确绘制Engel复盐相图及指导实际生产有重要意义.论文研究了低温条件下液相合成Engel复盐晶体的适宜条件,即碳酸氢钾饱和溶液中加入碱式碳酸镁,其重量比39.0 g/0.2 g,在40℃下水热反应10 min;然后反应溶液从40℃冷却降温到25℃进行析晶,析晶过程持续约7.0h,制备出Engel复盐晶体;对产物进行了XRD及晶体形貌分析,其衍射峰与标准图谱一致,晶体形貌规则,结晶良好.

  8. Low temperature in situ synthesis and the formation mechanism of various carbon-encapsulated nanocrystals by the electrophilic oxidation of metallocene complexes.

    Science.gov (United States)

    Liu, Boyang; Fan, Chunhua; Chen, Jianwei; Wang, Junhua; Lu, Zepeng; Ren, Jiayuan; Yu, Shuaiqin; Dong, Lihua; Li, Wenge

    2016-02-19

    The core-shell nanostructures have the advantages of combining distinctive properties of varied materials and improved properties over their single-component counterparts. Synthesis approaches for this class of nanostructures have been intensively explored, generally involving multiple steps. Here, a general and convenient strategy is developed for one-step in situ synthesis of various carbon-encapsulated nanocrystals with a core-shell structure via a solid-state reaction of metallocene complexes with (NH4)2S2O8 in an autoclave at 200 °C. A variety of near-spherical and equiaxed nanocrystals with a small median size ranging from 6.5 to 50.6 nm are prepared as inner cores, including Fe7S8, Ni3S4 and NiS, CoS, TiO2, TiO2 and S8, ZrO2, (NH4)3V(SO4)3 and VO2, Fe7S8 and Fe3O4, MoS2 and MoO2. The worm-like carbon shell provides exclusive room for hundreds of nanocrystals separated from each other, preventing nanocrystal aggregation. The synergistic effect of ammonium and a strong oxidizing anion on the electrophilic oxidation of metallocene complexes containing a metal-ligand π bond contributes to the carbon formation at low temperature. It is considered that the cyclopentadienyl ligand in a metallocene complex will decompose into highly reactive straight chain olefinic pieces and the metal-olefin π interaction enables an ordered self-assembly of olefinic pieces on nanocrystals to partially form graphitizable carbon and a core-shell structure. The high capacity, good cycling behavior and rate capability of Fe7S8@C and Ni3S4 and NiS@C electrodes are attributed to the good protection and electrical conductivity of the carbon shell.

  9. Methanol synthesis on potassium modified Cu(100) from CO + H2 and CO + CO2 +H2

    DEFF Research Database (Denmark)

    Maack, M.; Friis-Jensen, Henriette; Sckerl, Susanne Quist;

    2003-01-01

    Methanol cannot be produced from CO + H-2 on a clean copper surface, but a promotional effect of potassium on methanol synthesis from mixtures of CO + H-2 and CO = CO2 + H-2 at a total pressure of 1.5 bar on a Cu(100) surface is shown in this work. The experiments are performed in a UHV chamber...... connected with a high-pressure cell (HPC). The methanol produced is measured with a gas chromatograph and the surface is characterized with surface science techniques. The results show that potassium is a promoter for the methanol synthesis from CO + H-2, and that the influence of CO2 is negligible....... Investigation of the post-reaction surface with TPD indicates that potassium carbonate is present and plays an important role. The activation energy is determined as 42 +/- 3 kJ/mol for methanol synthesis on K/Cu(100) from CO + H-2....

  10. In situ X-ray photoelectron spectroscopy of methanol steam reforming on Cu/ZnO catalysts

    OpenAIRE

    2004-01-01

    Cu/ZnO (alumina) catalysts have found industrial use for the low-temperature methanol synthesis, for the low-temperature water-gas shift reaction, and for the steam reforming of methanol. An important application could be the onboard production of hydrogen for fuel cell application. It is the proposed synergistic effect in the binary copper/zinc oxide that makes this system interesting for investigation. The knowledge of the relationship between the catalytic activity, surface structure, a...

  11. Low-temperature synthesis, luminescence and phonon properties of Er and/or Dy doped LaAlO{sub 3} nanopowders

    Energy Technology Data Exchange (ETDEWEB)

    Maczka, MirosLaw, 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 WrocLaw 2 (Poland); Mendoza-Mendoza, Esmeralda; Fuentes, Antonio F. [Cinvestav Unidad Saltillo, Apartado Postal 663, Saltillo, 25000 Coahuila (Mexico); Lemanski, Karol; Deren, PrzemysLaw [Institute of Low Temperature and Structure Research, Polish Academy of Sciences, P.O. Box 1410, 50-950 WrocLaw 2 (Poland)

    2012-03-15

    LaAlO{sub 3}, La{sub 0.9}Dy{sub 0.1}AlO{sub 3}, La{sub 0.9}Er{sub 0.1}AlO{sub 3} and La{sub 0.8}Dy{sub 0.1}Er{sub 0.1}AlO{sub 3} nanocrystalline powders were synthesized in a two-step process by combining a mechanically induced metathesis reaction and molten salt synthesis. The proposed two-step methodology easily allows obtaining pure and/or doped perovskite-type LaAlO{sub 3} nanopowders at remarkably low temperatures, i.e., already at 350 Degree-Sign C although firing at 500 Degree-Sign C is needed in order to get pure phases. The obtained samples were characterized by XRD, TEM, Raman, IR and luminescence methods. These methods showed that the mean crystallite size is near 50-60 nm and the LaAlO{sub 3} nanocrystallites have R3{sup Macron }c structure, the same as bulk LaAlO{sub 3}. Raman spectrum of nanocrystalline LaAlO{sub 3} is very similar to that of bulk. In contrast to this behavior, IR spectra of the synthesized compounds are significantly different from the IR spectrum of bulk LaAlO{sub 3}. Origin of this behavior is discussed. Luminescence study showed that the cross-relaxation processes quench emission intensity of the samples doped with Dy{sup 3+} and Er{sup 3+}. - Graphical abstract: TEM image of La{sub 0.9}Er{sub 0.1}AlO{sub 3} (left panel) and histogram showing the particle size distribution (right panel). Highlights: Black-Right-Pointing-Pointer Pure and Er or Dy doped LaAlO3 samples were synthesized at remarkably low temperatures. Black-Right-Pointing-Pointer The mean crystallite size of the obtained samples is 40-60 nm. Black-Right-Pointing-Pointer Nanocrystallites have R3{sup Macron }c structure, the same as bulk LaAlO3. Black-Right-Pointing-Pointer IR spectra are significantly different from the IR spectrum of bulk. Black-Right-Pointing-Pointer We discuss origin of this behavior.

  12. 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.

  13. Novel Diamond Films Synthesis Strategy: Methanol and Argon Atmosphere by Microwave Plasma CVD Method Without Hydrogen

    Science.gov (United States)

    Yang, Li; Jiang, Caiyi; Guo, Shenghui; Zhang, Libo; Gao, Jiyun; Peng, Jinhui; Hu, Tu; Wang, Liang

    2016-09-01

    Diamond thin films are grown on silicon substrates by only using methanol and argon mixtures in microwave plasma chemical vapor deposition (MPCVD) reactor. It is worth mentioning that the novel strategy makes the synthesis reaction works smoothly without hydrogen atmosphere, and the substrates temperature is only 500 °C. The evidence of surface morphology and thickness under different time is obtained by characterizing the samples using scanning electron microscopy (SEM). X-ray diffractometer (XRD) spectrum reveals that the preferential orientation of (111) plane sample is obtained. The Raman spectra indicate that the dominant component of all the samples is a diamond. Moreover, the diamond phase content of the targeted films was quantitatively analyzed by X-ray photoelectron spectroscopy (XPS) method, and the surface roughness of diamond films was investigated by atomic force microscope (AFM). Meanwhile, the possible synthesis mechanism of the diamond films in methanol- and argon-mixed atmosphere was discussed.

  14. Method for making methanol

    Science.gov (United States)

    Mednick, R. Lawrence; Blum, David B.

    1986-01-01

    Methanol is made in a liquid-phase methanol reactor by entraining a methanol-forming catalyst in an inert liquid and contacting said entrained catalyst with a synthesis gas comprising hydrogen and carbon monoxide.

  15. Low-temperature synthesis of Mn-based mixed metal oxides with novel fluffy structures as efficient catalysts for selective reduction of nitrogen oxides by ammonia.

    Science.gov (United States)

    Meng, Bo; Zhao, Zongbin; Chen, Yongsheng; Wang, Xuzhen; Li, Yong; Qiu, Jieshan

    2014-10-21

    A series of Mn-based mixed metal oxide catalysts (Co-Mn-O, Fe-Mn-O, Ni-Mn-O) with high surface areas were prepared via low temperature crystal splitting and exhibited extremely high catalytic activity for the low-temperature selective catalytic reduction of nitrogen oxides with ammonia.

  16. 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.

  17. N-heterocyclic carbene catalyzed synthesis of dimethyl carbonate via transesterification of ethylene carbonate with methanol

    Directory of Open Access Journals (Sweden)

    Guang-Fen Du

    2015-01-01

    Full Text Available An organocatalytic protocol for the synthesis of dimethyl carbonate has been developed. Under the catalysis of 5 mol% N-heterocyclic carbenes, ethylene carbonate undergoes transesterification reaction with methanol under very mild reaction conditions, producing dimethyl carbonate with high efficiency. Furthermore, this N-heterocyclic carbene promoted transesterification can be scaled-up easily without lose of the conversion of dimethyl carbonate.

  18. Engineering Methylobacterium extorquens for de novo synthesis of the sesquiterpenoid α-humulene from methanol.

    Science.gov (United States)

    Sonntag, Frank; Kroner, Cora; Lubuta, Patrice; Peyraud, Rémi; Horst, Angelika; Buchhaupt, Markus; Schrader, Jens

    2015-11-01

    Over the last 10 to 15 years, metabolic engineering of microbes has become a versatile tool for high-level de novo synthesis of terpenoids, with the sesquiterpenoids armopha-1,4-diene, farnesene and artemisinic acid as prime examples. However, almost all cell factory approaches towards terpenoids to date have been based on sugar as the raw material, which is mainly used as a food resource and subject to high price volatilities. In this study we present de novo synthesis of the sesquiterpenoid α-humulene from the abundantly available non-food carbon source methanol by metabolically engineered Methylobacterium extorquens AM1. Expression of α-humulene synthase from Zingiber zerumbet in combination with farnesyl pyrophosphate (FPP) synthase from Saccharomyces cerevisiae led to concentrations of up to 18 mg/L α-humulene. Introduction of a prokaryotic mevalonate pathway from Myxococcus xanthus in combination with ribosome binding site optimization of α-humulene and FPP synthases increased product concentration 3-fold. This value was additionally raised by 30% using a carotenoid synthesis deficient mutant strain. Final product concentrations of up to 1.65 g/L were obtained in methanol limited fed-batch cultivations, which is the highest titer of de novo synthesized α-humulene reported to date. This study demonstrates the potential of M. extorquens as a future platform strain for the production of high-value terpenoids from the alternative carbon source methanol.

  19. The Factors of Affecting Methanol Synthesis%影响甲醇合成的因素

    Institute of Scientific and Technical Information of China (English)

    陈媛媛

    2012-01-01

    甲醇是重要的有机化工原料和优质燃料。主要用于制造甲醛、醋酸、氯甲烷、甲氨、硫酸二甲脂等多种有机产品,也是农药、医药的重要原料之一。甲醇亦可代替汽油作燃料使用。本文通过甲醇合成的发展历史和合成技术的阐述,讨论了影响甲醇合成的几个重要因素,对甲醇生产有指导意义。%Methanol was an important organic chemical raw material and high-quality fuel,mainly used in the manufacture offormaldehyde,acetic acid,methyl chloride,ammonia,sulfuric acid,dimethyl grease and other organic products,and also one of the important raw material of apesticide and medicine.Themethanol can replace gasoline as fuel use.Through the discussion of development of methanol synthesis history and synthesis technology,several important factors influencing methanol synthesis were explored,which had guidance for methand production.

  20. Unprecedented synthesis of chiral calix[4](aza)crowns and its potent encapsulating methanol

    Institute of Scientific and Technical Information of China (English)

    LI ZhengYi; TENG MingYu; MA JieJie; HUANG Ji; WANG LeYong; PAN Yi

    2009-01-01

    Unprecedented synthesis of chiral (aza)crown ethers of calix[4]arene derivatives bearing a carboxyl amide bridge was described. The synthesis proceeds through condensation of the corresponding dinitriles with optically active 1,2-aminoalcohols, and is catalyzed by the ZnCl2 Lewis acid at elevated temperature in a very efficient one-pot process. The cavity of calix[4](aza)crowns can encapsulate methanol molecules by O-H…п interaction, which has been confirmed by X-ray crystal structures and ESI-MS.

  1. Unprecedented synthesis of chiral calix[4](aza)crowns and its potent encapsulating methanol

    Institute of Scientific and Technical Information of China (English)

    2009-01-01

    Unprecedented synthesis of chiral (aza)crown ethers of calix[4]arene derivatives bearing a carboxyl amide bridge was described. The synthesis proceeds through condensation of the corresponding dinitriles with optically active 1,2-aminoalcohols,and is catalyzed by the ZnCl2 Lewis acid at elevated temperature in a very efficient one-pot process. The cavity of calix[4](aza)crowns can encapsulate methanol molecules by O-H...π interaction,which has been confirmed by X-ray crystal structures and ESI-MS.

  2. 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.

  3. 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 (GCEO

  4. Study on Highly Active Catalysts and a Once-Through Process for Methanol Synthesis from Syngas

    Institute of Scientific and Technical Information of China (English)

    Xin Dong; Bingshun Shen; Hongbin Zhang; Guodong Lin; Youzhu Yuan

    2003-01-01

    Highly active CNT-promoted co-precipitated Cu-ZnO-Al2O3 catalysts, symbolized asCuiZnjAlk-x%CNTs, were prepared, and their catalytic activity for once-through methanol synthesis fromsyngas was investigated. The results illustrated that, under the reaction conditions (at 493 K, 5.0 MPa, thevolume ratio of H2/CO/CO2/N2= 62/30/5/3, GHSV= 4000 h-1), the observed single-pass CO-conversionand methanol-STY over a Cu6Zn3Al1-12.5%CNTs catalyst reached 64% and 1210 mg/(h@g), which wasabout 68% and 66% higher than those (38% and 730 mg/(h@g)) over the corresponding CNT-free catalyst,Cu6Zn3Al1, respectively. The characteristic studies of the catalysts revealed that appropriate incorporationof a minor amount of the CNTs into the CuiZnjAlk brought about little change in the apparent activationenergy of the methanol synthesis reaction, however, led to a considerable increase in the catalyst's active Cusurface area and pronouncedly enhanced the stationary-state concentration of active hydrogen-adspecieson the surface of the functioning catalyst, which would be favorable to increasing the rate of the CO hydro-genation reactions. Moreover, the operation temperature for methanol synthesis over the CNT-promotedcatalysts can be 10-20 degrees lower than that over the corresponding CNT-free contrast system, whichwould contribute considerably to an increase in equilibrium CO-conversion and CH3OH-yield.

  5. Dynamic modeling of a H2O-permselective membrane reactor to enhance methanol synthesis from syngas considering catalyst deactivation

    Institute of Scientific and Technical Information of China (English)

    M.Farsi; A.Jahanmiri

    2012-01-01

    In this paper,the effect of water vapor removal on methanol synthesis capacity from syngas in a fixed-bed membrane reactor is studied considering long-term catalyst deactivation.A dynamic heterogeneous one-dimensional mathematical model that is composed of two sides is developed to predict the performance of this configuration.In this configuration,conventional methanol reactor is supported by an aluminasilica composite membrane layer for water vapor removal from reaction zone.To verify the accuracy of the considered model and assumptions,simulation results of the conventional methanol reactor is compared with the industrial plant data under the same process condition.The membrane reactor improves catalyst life time and enhances CO2 conversion to methanol by overcoming the limitation imposed by thermodynamic equilibrium.This configuration has enhanced the methanol production capacity about 4.06% compared with the industrial methanol reactor during the production time.

  6. Efficient Synthesis of Dimethyl Ether from Methanol in a Bifunctional Zeolite Membrane Reactor.

    Science.gov (United States)

    Zhou, Chen; Wang, Nanyi; Qian, Yanan; Liu, Xiaoxing; Caro, Jürgen; Huang, Aisheng

    2016-10-04

    A sandwich FAU-LTA zeolite dual-layer membrane has been developed and used as a catalytic membrane reactor for the synthesis of dimethyl ether (DME). In the top H-FAU layer with mild acidity, methanol is dehydrated to DME. The other reaction product, water, is removed in situ through a hydrophilic Na-LTA layer, which is located between the porous alumina support and the H-FAU top layer. The combination of mild acidity with the continuous removal of water results in high methanol conversion (90.9 % at 310 °C) and essentially 100 % DME selectivity. Furthermore, owing to the selective and continuous removal of water through the Na-LTA membrane, catalyst deactivation can be effectively suppressed. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  7. Methanol synthesis on ZnO(0001{sup ¯}). IV. Reaction mechanisms and electronic structure

    Energy Technology Data Exchange (ETDEWEB)

    Frenzel, Johannes, E-mail: johannes.frenzel@theochem.rub.de; Marx, Dominik [Lehrstuhl für Theoretische Chemie, Ruhr-Universität Bochum, 44780 Bochum (Germany)

    2014-09-28

    Methanol synthesis from CO and H{sub 2} over ZnO, which requires high temperatures and high pressures giving rise to a complex interplay of physical and chemical processes over this heterogeneous catalyst surface, is investigated using ab initio simulations. The redox properties of the surrounding gas phase are known to directly impact on the catalyst properties and thus, set the overall catalytic reactivity of this easily reducible oxide material. In Paper III of our series [J. Kiss, J. Frenzel, N. N. Nair, B. Meyer, and D. Marx, J. Chem. Phys. 134, 064710 (2011)] we have qualitatively shown that for the partially hydroxylated and defective ZnO(0001{sup ¯}) surface there exists an intricate network of surface chemical reactions. In the present study, we employ advanced molecular dynamics techniques to resolve in detail this reaction network in terms of elementary steps on the defective surface, which is in stepwise equilibrium with the gas phase. The two individual reduction steps were investigated by ab initio metadynamics sampling of free energy landscapes in three-dimensional reaction subspaces. By also sampling adsorption and desorption processes and thus molecular species that are in the gas phase but close to the surface, our approach successfully generated several alternative pathways of methanol synthesis. The obtained results suggest an Eley-Rideal mechanism for both reduction steps, thus involving “near-surface” molecules from the gas phase, to give methanol preferentially over a strongly reduced catalyst surface, while important side reactions are of Langmuir-Hinshelwood type. Catalyst re-reduction by H{sub 2} stemming from the gas phase is a crucial process after each reduction step in order to maintain the catalyst's activity toward methanol formation and to close the catalytic cycle in some reaction channels. Furthermore, the role of oxygen vacancies, side reactions, and spectator species is investigated and mechanistic details are

  8. Methanol synthesis on ZnO(0001¯). IV. Reaction mechanisms and electronic structure.

    Science.gov (United States)

    Frenzel, Johannes; Marx, Dominik

    2014-09-28

    Methanol synthesis from CO and H2 over ZnO, which requires high temperatures and high pressures giving rise to a complex interplay of physical and chemical processes over this heterogeneous catalyst surface, is investigated using ab initio simulations. The redox properties of the surrounding gas phase are known to directly impact on the catalyst properties and thus, set the overall catalytic reactivity of this easily reducible oxide material. In Paper III of our series [J. Kiss, J. Frenzel, N. N. Nair, B. Meyer, and D. Marx, J. Chem. Phys. 134, 064710 (2011)] we have qualitatively shown that for the partially hydroxylated and defective ZnO(0001¯) surface there exists an intricate network of surface chemical reactions. In the present study, we employ advanced molecular dynamics techniques to resolve in detail this reaction network in terms of elementary steps on the defective surface, which is in stepwise equilibrium with the gas phase. The two individual reduction steps were investigated by ab initio metadynamics sampling of free energy landscapes in three-dimensional reaction subspaces. By also sampling adsorption and desorption processes and thus molecular species that are in the gas phase but close to the surface, our approach successfully generated several alternative pathways of methanol synthesis. The obtained results suggest an Eley-Rideal mechanism for both reduction steps, thus involving "near-surface" molecules from the gas phase, to give methanol preferentially over a strongly reduced catalyst surface, while important side reactions are of Langmuir-Hinshelwood type. Catalyst re-reduction by H2 stemming from the gas phase is a crucial process after each reduction step in order to maintain the catalyst's activity toward methanol formation and to close the catalytic cycle in some reaction channels. Furthermore, the role of oxygen vacancies, side reactions, and spectator species is investigated and mechanistic details are discussed based on extensive

  9. Methanol synthesis on ZnO(000overline{1}). IV. Reaction mechanisms and electronic structure

    Science.gov (United States)

    Frenzel, Johannes; Marx, Dominik

    2014-09-01

    Methanol synthesis from CO and H2 over ZnO, which requires high temperatures and high pressures giving rise to a complex interplay of physical and chemical processes over this heterogeneous catalyst surface, is investigated using ab initio simulations. The redox properties of the surrounding gas phase are known to directly impact on the catalyst properties and thus, set the overall catalytic reactivity of this easily reducible oxide material. In Paper III of our series [J. Kiss, J. Frenzel, N. N. Nair, B. Meyer, and D. Marx, J. Chem. Phys. 134, 064710 (2011)] we have qualitatively shown that for the partially hydroxylated and defective ZnO(000overline{1}) surface there exists an intricate network of surface chemical reactions. In the present study, we employ advanced molecular dynamics techniques to resolve in detail this reaction network in terms of elementary steps on the defective surface, which is in stepwise equilibrium with the gas phase. The two individual reduction steps were investigated by ab initio metadynamics sampling of free energy landscapes in three-dimensional reaction subspaces. By also sampling adsorption and desorption processes and thus molecular species that are in the gas phase but close to the surface, our approach successfully generated several alternative pathways of methanol synthesis. The obtained results suggest an Eley-Rideal mechanism for both reduction steps, thus involving "near-surface" molecules from the gas phase, to give methanol preferentially over a strongly reduced catalyst surface, while important side reactions are of Langmuir-Hinshelwood type. Catalyst re-reduction by H2 stemming from the gas phase is a crucial process after each reduction step in order to maintain the catalyst's activity toward methanol formation and to close the catalytic cycle in some reaction channels. Furthermore, the role of oxygen vacancies, side reactions, and spectator species is investigated and mechanistic details are discussed based on

  10. Temperature reduction of A301 type low temperature ammonia synthesis catalyst%A301型低温氨合成催化剂的升温还原

    Institute of Scientific and Technical Information of China (English)

    王志峰; 郭新法

    2014-01-01

    介绍了中煤化工公司的A301型低温氨合成催化剂的装填、升温还原要点、控制方案及还原时的注意事项。%This paper introduces backfill, temperature reduction point, control scheme and matters need attention of A301 type low temperature synthesis catalyst in National Coal Chemical Company.

  11. Promotion of Ionic Liquid to Dimethyl Carbonate Synthesis from Methanol and Carbon Dioxide

    Institute of Scientific and Technical Information of China (English)

    CAI,Qing-Hai(蔡清海); ZHANG,Li(张丽); SHAN,Yong-Kui(单永奎); HE,Ming-Yuan(何鸣元)

    2004-01-01

    Promotion of ionic liquid,1-ethyl-3-methylimidazolium bromide (emimBr),to the synthesis of dimethyl carbonate (DMC) from methanol and carbon dioxide in the presence of potassium carbonate and less amount of methyl iodide under mild conditions was investigated.The results showed that the high selectivity and raised yield of DMC was achieved due to the addition of emimBr in the reaction system.And effect of several reaction conditions such as temperature,pressure and amount of emimBr was discussed.

  12. Experimental measurement of the thermal stability criteria for low pressure methanol synthesis

    Energy Technology Data Exchange (ETDEWEB)

    Berty, J.M.; Lenczyk, J.P.; Shah, S.M.

    1982-11-01

    The mathematical basis was derived for the experimental measurement of the ''Slope Condition'' and of the ''Dynamic Condition'' of the thermal stability criteria in a laboratory-scale internal recycle reactor. This work also resulted in clearer interpretations and simpler expressions for the two stability criteria. The method was experimentally demonstrated on the example of the low pressure methanol synthesis. Only seven experiments were needed to evaluate the stability criteria of this reaction for which the kinetics is unknown.

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

    Science.gov (United States)

    Jiao, Wei-Hong; Liu, Shi-Zhong; Zuo, Zhi-Jun; Ren, Rui-Peng; Gao, Zhi-Hua; Huang, Wei

    2016-11-01

    Methanol synthesis from CO/CO2 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 → H2CO → H3CO → H3COH; in the case of WGS, the reaction pathways in liquid paraffin and vacuum are CO + 2H2O → CO + 2OH + 2H → CO + H2O + O + H2 → CO2 + H2O + H2; the reaction pathways of methanol synthesis from CO2 hydrogenation in liquid paraffin and vacuum are CO2 + H → HCOO → H2COO → H2CO → H3CO → H3COH and CO2 + H → HCOO → HCOOH → H2COOH → H3CO → H3COH, 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 CO2 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.

  14. Comprehensive Evaluation of Methanol Synthesis and Utilization System for Making Use of Remote Wind Power Energy

    Science.gov (United States)

    Morimoto, Shin'Ichiro; Pak, Pyong Sik; Liu, Wei; Kosugi, Takanobu

    For the purpose of mitigating carbon dioxide emissions, three renewable energy transportation systems are proposed in which methanol is synthesized by use of wind power generation energy at an oversea and is transported to Japan to be used for a power generation. The proposed systems are the following three systems: (1) wind energy and captured CO2 utilization system, (2) wind energy and coal utilization system, and (3) wind energy and biomass utilization system. The characteristic and cost of the proposed systems’ components such as a wind power generation and a methanol synthesis plants are investigated, and so are the energy and carbon flows of the systems, assuming that the wind power generation plant is constructed at the eastern coast of Russia. Major indicators such as energy efficiency, methanol cost, CO2 reduction cost, etc., of the proposed systems are evaluated together with those of a similar CO2 recycling system utilizing hydraulic power. On the basis of the evaluation results, the wind energy and biomass utilization system is shown to be the most excellent among the evaluated systems from the viewpoints of the CO2 reduction cost. When LNG cost is increased, its estimated CO2 reduction cost islower than that of a CO2 recovery system adopted to a conventional LNG-fired power plant. Consequently, the proposed system is expected to be a feasible option for CO2 reduction in the near future when the wind power generation cost is much decreased.

  15. 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 promoter for this type of catalyst is still under intense debate.2 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...

  16. 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 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...

  17. 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).

  18. GREEN SYNTHESIS OF GOLD NANOPARTICLES USING TOONA CILIATA METHANOL BARK EXTRACT AND THEIR CHARACTERISATION

    Directory of Open Access Journals (Sweden)

    Kaushik Rajan

    2012-09-01

    Full Text Available In the present study, we identified and justified the use of MeOH extract from Toona ciliata bark as a reducing and capping agent for the ecofriendly synthesis of gold nanoparticles on the basis of modern analytical techniques. The reduction of 1.0 mM aqueous solution of aurochloric acid with 1 ml, 1% w/v aqueous solution of MeOH bark extract from Toona ciliata has resulted in the formation of stabilised Gold Nanoparticles (AuNPs. The synthesised gold particles showed a surface plasmon band around 550 nm when analysed via UV-Visible Spectroscopy, indicated the gold particles of nano dimensions (10-9 m. The Transmission Electron Microscopy (TEM study of gold nano particles revealed the formation of spherical, poly dispersed nanoparticles of varying sizes ranging from 40-75 nm along with encapsulating cage. The time for the synthesis of gold nano particles was noted to be 30 minute. The preliminary phytochemical analysis of methanol extract form the bark confirmed the presence of alkaloids, glycosides, flavanoids, tannins and reducing sugars. The results of the present study clearly reveal the Toona ciliata methanolic bark extract as a new, novel and renewable, cost effective, reducing and capping agent for the application in the field of nanobiotechnology as well as pharmaceutical sciences. Further, the ecofriendly approach developed for AuNPs synthesis with Toona ciliata MeOH bark extract is the rapid and cost effective alternative to the traditional chemical methods of AuNPs synthesis.

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

    Institute of Scientific and Technical Information of China (English)

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

    2010-01-01

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

  20. Influence of Solvent on Reaction Path to Synthesis of Methyl N-Phenyl Carbamate from Aniline, CO2 and Methanol

    Institute of Scientific and Technical Information of China (English)

    安华良; 张丽丽; 苑保国; 赵新强; 王延吉

    2014-01-01

    Methyl N-phenyl carbamate (MPC), an important organic chemical, can be synthesized from aniline, CO2 and methanol. Catalyst Cu-Fe/ZrO2-SiO2 was first prepared and its catalytic performance for MPC synthesis was evaluated. Then the influence of solvent on the reaction path of MPC synthesis was investigated. It is found that the reaction intermediate is different with acetonitrile or methanol as a solvent. With acetonitrile as a solvent, the synthesis of MPC follows the reaction path with diphenyl urea as the intermediate, while with methanol as a solvent the reaction occurs via the reaction path with dimethyl carbonate as the intermediate. The catalytic mecha-nism of cooperative catalysis comprising metal sites, Lewis acid sites and Lewis base sites is proposed according to different reaction intermediates.

  1. Effects of carbon dioxide and water on the methanol synthesis catalyst

    Energy Technology Data Exchange (ETDEWEB)

    Lee, S.; Sawant, A.; Rodrigues, K.; Kulik, C.

    The effects of water and CO/sub 2/ on the metal content and chemical constitution of the methanol synthesis catalyst have been experimentally examined. The experiments have been performed with only water, CO/sub 2/, and N/sub 2/ in order to find the discerning effects and have not been performed under actual conditions for methanol synthesis. It has been shown that the presence of CO/sub 2/ promotes the leaching of metals from the catalyst. It has also been observed that the presence of CO/sub 2/ leads to the formation of (CuZn)/sub 2/CO/sub 3/(OH)/sub 2/ (rosasite). These results have been statistically analyzed. The effects of temperature, pressure, and CO/sub 2/ on the amount of metals leached out from the catalyst as well as the extent of formation of (CuZn)/sub 2/CO/sub 3/(OH)/sub 2/(rosasite) have been determined. 19 refs., 4 figs., 7 tabs.

  2. Vapor–liquid equilibria of triglycerides–methanol mixtures and their influence on the biodiesel synthesis under supercritical conditions of methanol

    Directory of Open Access Journals (Sweden)

    ALEKSANDAR ORLOVIC

    2007-01-01

    Full Text Available The non-catalytic synthesis of biodiesel (fatty acids methyl esters from triglycerides and methanol proceeds at elevated pressures above 100 bar and temperatures above 523 K. Kinetic investigations of the system revealed an unusual behavior of the reaction rate constant with increasing temperature and pressure. In order to explain this phenomenon, the phase behavior of the triglycerides–methanol mixture was investigated. The phase equilibria of the binary system sunflower oil–methanol were measured at different temperatures between 473 and 503 K, and a range of pressures between 10 and 56 bar. The experimental data were correlated using the Peng–Robinson, Soave–Redlich–Kwong and Redlich–Kwong–Aspen equations of state and different mixing rules. The best results were obtained with the RK–ASPEN equation of state and the Van derWaals mixing rule (VdW, which were then used to calculate the distribution of the phases at pressures and temperatures usual for the non-catalytic synthesis of biodiesel under high pressures. The obtained data indicated a strong influence of the phase equilibria on the reaction kinetics.

  3. Mass transfer in the liquid-phase methanol synthesis (LPMeOH)/sup TM/ process: Interim report

    Energy Technology Data Exchange (ETDEWEB)

    Lee, S.; Parameswaran, V.R.; Sawant, A.V.; Ko, M.K.

    1988-04-01

    This report is a sequel to the Interim Report AP-4429 titled /open quote/Research to Support Development of the Liquid Phase Methanol Synthesis Process/close quote/ (LPMEOH/sup TM/ Process). The focus of this report is on the mass transfer characteristics of the process when the reaction is carried out in a stirred slurry reactor. The relevant aspects of mass transfer theory have been explained and supported with extensive experimental data. As such, this report provides the necessary database for scale-up and design of a stirred slurry reactor for liquid-phase methanol synthesis. 17 refs., 35 figs., 12 tabs.

  4. Low-temperature synthesis to achieve high critical current density and avoid a reaction layer in SmFeAsO1-x F x superconducting tapes

    Science.gov (United States)

    Zhang, Qianjun; Lin, He; Yuan, Pusheng; Zhang, Xianping; Yao, Chao; Wang, Dongliang; Dong, Chiheng; Ma, Yanwei; Awaji, Satoshi; Watanabe, Kazuo

    2015-10-01

    A low-temperature (300-500 °C) heat treatment process under ambient pressure or uniaxial pressure was performed on Sn-added SmFeAsO1-x F x superconducting tapes fabricated by the ex situ powder-in-tube method. A highest transport critical current density (J c) of 3.95 × 104 A cm-2 (at 4.2 K and self-field) was achieved by this process. The low-temperature process allows tapes to endure much longer heat treatment without J c degradation than the high-temperature method. Microscopic analysis also revealed that this method could obtain a clear boundary without a reaction layer or interdiffusion between a superconducting core and sheath metal.

  5. 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

    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.

  6. Effects of synthesis methods on catalytic activities of CoOx-TiO2 for low-temperature NH3-SCR of NO.

    Science.gov (United States)

    Zhu, Li; Zeng, Yiqing; Zhang, Shule; Deng, Jinli; Zhong, Qin

    2017-04-01

    A series of cobalt doped TiO2 (Co-TiO2) and CoOx loaded TiO2 (Co/TiO2) catalysts prepared by sol-gel and impregnation methods respectively were investigated on selective catalytic reduction with NH3 (NH3-SCR) of NO. It was found that Co-TiO2 catalyst showed more preferable catalytic activity at low temperature range. From characterization results of XRD, TEM, Raman and FT-IR, Co species were proved to be doped into TiO2 lattice by replaced Ti atoms. After being characterized and analyzed by NH3-TPD, PL, XPS, EPR and DRIFTS, it was found that the better NH3-SCR activities of Co-TiO2 catalysts, compared with Co/TiO2 catalyst, were ascribed to the formation of more oxygen vacancies which further promoted the production of more superoxide ions (O2(-)). The superoxide ions were crucial for the formation of low temperature SCR reaction intermediates (NO3(-)) by reacting with adsorbed NO molecule. Therefore, these aspects were responsible for the higher low temperature NH3-SCR activity of Co-TiO2 catalysts.

  7. Using non-equilibrium state in the MoO3 -H-C system for low temperature synthesis of ultradispersed molybdenum carbide powders

    Directory of Open Access Journals (Sweden)

    M.P. Savyak

    2008-12-01

    Full Text Available Pd additives and atomic hydrogen can accelerate kinetic processes in molybdenum reduction from molybdenum trioxide with hydrogen at 350°C in the presence of carbon. Such a low temperature reduction process (starting temperature 300–350°C promotes the formation of a thermodynamically unstable nanodispersed phase with the specific surface area of 280 m2/g, which may be related to the formation of the intermediate cubic molybdenum suboxide Mo1-xO, responsible for the preservation of the MoO3 faceting. The specific surface area of 280 m2/g corresponds to the particle size ~3 nm. The phase transformation leading to the formation of Mo2C in the MoO3-Pd-H2-C system at a relatively low temperature (650°C is the result of relaxation of the high free energy in the thermodynamically unstable system. The carbide formation process at such a low temperature yields carbide with the specific surface area from 4 to 40 m2/g (depending on the carbide-forming component, which can be easy sintered. The morphology of this carbide inherits the faceting of the initial whiskerous trioxide molybdenum. The microhardness of the sintered samples is significantly higher than that of carbide produced traditionally at high temperature.

  8. 低温水相一步合成钛酸钡:热力学模型化及实验合成研究%Low Temperature One-Step Synthesis of Barium Titanate:Thermodynamic Modeling and Experimental Synthesis

    Institute of Scientific and Technical Information of China (English)

    沈志刚; 李世刚; 刘朝文; 张建文; 陈建峰

    2005-01-01

    A thermodynamic model has been developed to determine the reaction conditions favoring low temperature direct synthesis of barium titanate (BaTiO3). The method utilizes standard-state thermodynamic data for solid and aqueous species and a Debye-Hiickel coefficients model to represent solution nonideality. The method has been used to generate phase stability diagrams that indicate the ranges of pH and reagent concentrations, for which various species predominate in the system at a given temperature. Also, yield diagrams have been constructed that indicate the concentration, pH and temperature conditions for which different yields of crystalline BaTiO3 can be obtained. The stability and yield diagrams have been used to predict the optimum synthesis conditions (e.g.,reagent concentrations, pH and temperature). Subsequently, these predictions have been experimentally verified.As a result, phase-pure perovskite BaTiO3 has been obtained at temperature ranging from 55 to 85℃ using BaCl2,TiCl4 as a source for Ba and Ti, and NaOH as a precipitator.

  9. Purification Influence of Synthesis Gas Derived from Methanol Cracking on the Performance of Cobalt Catalyst in Fischer-Tropsch Synthesis

    Institute of Scientific and Technical Information of China (English)

    Wei Zhou; Shengying Liu; Yulan Wang; Kegong Fang; Jiangang Chen; Yuhan Sun

    2005-01-01

    Synthesis gas derived from methanol cracking (SGMC) was applied as simulating feedstock of Fischer-Tropsch synthesis (FTS) in laboratory. With MS and GC detector, a trifle of sulfur compounds,a small amount of oxygenates including H2O, CH3OH, DME and CO2 as well as a few of low carbon alkanes were found in the SGMC. After purification, the sulfur compounds, H2O, CH3OH and DME could be eliminated efficiently from the SGMC while CO2 and the low carbon alkanes were partly removed.When the unpurified SGMC, the desufurized SGMC and the totally purified SGMC were sequentially applied in cobalt-based FTS, the catalytic performance of Co/ZrO2/SiO2 catalyst was gradually improved corresponding to the degree of purification. The untreated SGMC led to the serious deactivation of the cobalt catalyst, the partially treated SGMC slowed down the deactivation rate and the totally purified SGMC resulted in little deactivation of the catalyst, which was similar to what the pure synthesis gas(the mixture of pure H2 and CO) did. The results indicated that the SGMC should be purified and the purification course used in this paper was effective for the SGMC. Furthermore, the totally purified SGMC could substitute for the pure synthesis gas in cobalt FTS.

  10. 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.

  11. A phase-transfer assisted solvo-thermal strategy for low-temperature synthesis of Na3(VO1-xPO4)2F1+2x cathodes for sodium-ion batteries.

    Science.gov (United States)

    Zhao, Junmei; Mu, Linqin; Qi, Yuruo; Hu, Yong-Sheng; Liu, Huizhou; Dai, Sheng

    2015-04-28

    We demonstrate that a series of high-performance cathode materials, sodium vanadium polyanionic compounds, Na3(VO1-xPO4)2F1+2x (x = 0, 0.5 and 1), can be synthesized by a phase-transfer assisted solvo-thermal strategy at a rather low temperature (80-140 °C) in one simple step, exhibiting a high Na storage capacity of ca. 120 mA h g(-1) and excellent cycling performance. This study makes a significant step to extend this strategy to the synthesis of functional materials from simple binary to complex multicomponent compounds.

  12. Pd-Modified Cu–Zn Catalysts for Methanol Synthesis from CO2/H2 Mixtures : Catalytic Structures and Performance

    NARCIS (Netherlands)

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

    2002-01-01

    The effect of palladium incorporation on the performance of a CuO–ZnO catalyst for methanol synthesis by hydrogenation of carbon dioxide is studied. Three different catalysts are prepared: the reference CuO-ZnO (CZ), and two Pd-based CuO–ZnO catalysts, PCZ-CP and PCZ-SP, which are prepared by co-pre

  13. Dual template synthesis of a highly mesoporous SSZ-13 zeolite with improved stability in the methanol-to-olefins reaction

    OpenAIRE

    Wu, Leilei; Degirmenci, Volkan; Magusin, Pieter; Szyja, Bartlomiej M; Hensen, Emiel J.M.

    2012-01-01

    The dual template synthesis of zeolite SSZ-13 by use of trimethyl-adamantanammonium hydroxide and a diquaternary-ammonium mesoporogen induces considerable mesoporosity without impeding zeolite microporosity. The strongly improved accessibility of Brønsted sites in mesoporous SSZ-13 increases its stability during application as an acid catalyst in the methanol-to-olefins reaction.

  14. Dual template synthesis of a highly mesoporous SSZ-13 zeolite with improved stability in the methanol-to-olefins reaction.

    Science.gov (United States)

    Wu, Leilei; Degirmenci, Volkan; Magusin, Pieter C M M; Szyja, Bartłomiej M; Hensen, Emiel J M

    2012-10-04

    The dual template synthesis of zeolite SSZ-13 by use of trimethyl-adamantanammonium hydroxide and a diquaternary-ammonium mesoporogen induces considerable mesoporosity without impeding zeolite microporosity. The strongly improved accessibility of Brønsted sites in mesoporous SSZ-13 increases its stability during application as an acid catalyst in the methanol-to-olefins reaction.

  15. Experimental determination and modeling of the phase behavior for the direct synthesis of dimethyl carbonate from methanol and carbon dioxide

    DEFF Research Database (Denmark)

    Tsivintzelis, Ioannis; Musko, Nikolai E.; Baiker, Alfons

    2013-01-01

    This study focuses on the investigation of the phase behavior of mixtures relevant to the direct synthesis of dimethyl carbonate from methanol and carbon dioxide. The bubble points of corresponding quaternary mixtures of varying composition were experimentally determined. The Cubic-Plus-Associati...

  16. Indium Oxide as a Superior Catalyst for Methanol Synthesis by CO2 Hydrogenation.

    Science.gov (United States)

    Martin, Oliver; Martín, Antonio J; Mondelli, Cecilia; Mitchell, Sharon; Segawa, Takuya F; Hauert, Roland; Drouilly, Charlotte; Curulla-Ferré, Daniel; Pérez-Ramírez, Javier

    2016-05-17

    Methanol synthesis by CO2 hydrogenation is attractive in view of avoiding the environmental implications associated with the production of the traditional syngas feedstock and mitigating global warming. However, there still is a lack of efficient catalysts for such alternative processes. Herein, we unveil the high activity, 100 % selectivity, and remarkable stability for 1000 h on stream of In2 O3 supported on ZrO2 under industrially relevant conditions. This strongly contrasts to the benchmark Cu-ZnO-Al2 O3 catalyst, which is unselective and experiences rapid deactivation. In-depth characterization of the In2 O3 -based materials points towards a mechanism rooted in the creation and annihilation of oxygen vacancies as active sites, whose amount can be modulated in situ by co-feeding CO and boosted through electronic interactions with the zirconia carrier. These results constitute a promising basis for the design of a prospective technology for sustainable methanol production.

  17. Microwave synthesis of polymer-embedded Pt-Ru catalyst for direct methanol fuel cell.

    Science.gov (United States)

    Bensebaa, Farid; Farah, Abdiaziz A; Wang, Dashan; Bock, Christina; Du, Xiaomei; Kung, Judy; Le Page, Yvon

    2005-08-18

    Platinum-ruthenium nanoparticles stabilized within a conductive polymer matrix are prepared using microwave heating. Polypyrrole di(2-ethylhexyl) sulfosuccinate, or PPyDEHS, has been chosen for its known electrical conductivity, thermal stability, and solubility in polar organic solvents. A scalable and quick two-step process is proposed to fabricate alloyed nanoparticles dispersed in PPyDEHS. First a mixture of PPyDEHS and metallic precursors is heated in a microwave under reflux conditions. Then the nanoparticles are extracted by centrifugation. Physical characterization by TEM shows that crystalline and monodisperse alloyed nanoparticles with an average size of 2.8 nm are obtained. Diffraction data show that crystallite size is around 2.0 nm. Methanol electro-oxidation data allow us to propose these novel materials as potential candidates for direct methanol fuel cells (DMFC) application. The observed decrease in sulfur content in the polymer upon incorporation of PtRu nanoparticles may have adversely affected the measured catalytic activity by decreasing the conductivity of PPyDEHS. Higher concentration of polymer leads to lower catalyst activity. Design and synthesis of novel conductive polymers is needed at this point to enhance the catalytic properties of these hybrid materials.

  18. Low-Temperature Facile Synthesis of Sb-Doped p-Type ZnO Nanodisks and Its Application in Homojunction Light-Emitting Diode.

    Science.gov (United States)

    Baek, Sung-Doo; Biswas, Pranab; Kim, Jong-Woo; Kim, Yun Cheol; Lee, Tae Il; Myoung, Jae-Min

    2016-05-25

    This study explores low-temperature solution-process-based seed-layer-free ZnO p-n homojunction light-emitting diode (LED). In order to obtain p-type ZnO nanodisks (NDs), antimony (Sb) was doped into ZnO by using a facile chemical route at 120 °C. The X-ray photoelectron spectra indicated the presence of (SbZn-2VZn) acceptor complex in the Sb-doped ZnO NDs. Using these NDs as freestanding templates, undoped n-type ZnO nanorods (NRs) were epitaxially grown at 95 °C to form ZnO p-n homojunction. The homojunction with a turn-on voltage of 2.5 V was found to be significantly stable up to 100 s under a constant voltage stress of 5 V. A strong orange-red emission was observed by the naked eye under a forward bias of 5 V. The electroluminescence spectra revealed three major peaks at 400, 612, and 742 nm which were attributed to the transitions from Zni to VBM, from Zni to Oi, and from VO to VBM, respectively. The presence of these deep-level defects was confirmed by the photoluminescence of ZnO NRs. This study paves the way for future applications of ZnO homojunction LEDs using low-temperature and low-cost solution processes with the controlled use of native defects.

  19. Controlled reactive HiPIMS—effective technique for low-temperature (300 °C) synthesis of VO2 films with semiconductor-to-metal transition

    Science.gov (United States)

    Vlček, J.; Kolenatý, D.; Houška, J.; Kozák, T.; Čerstvý, R.

    2017-09-01

    Reactive high-power impulse magnetron sputtering with a pulsed O2 flow control and to-substrate O2 injection into a high-density plasma in front of the sputtered vanadium target was used for low-temperature (300 °C) deposition of VO2 films with a pronounced semiconductor-to-metal transition onto conventional soda-lime glass substrates without any substrate bias voltage and without any interlayer. The depositions were performed using an unbalanced magnetron with a planar target of 50.8 mm diameter in argon-oxygen gas mixtures at the argon pressure of 1 Pa. The deposition-averaged target power density was close to 13 W cm-2 at a fixed duty cycle of 1% with a peak target power density up to 5 kW cm-2 during voltage pulses ranged from 40 µs to 100 µs. A high modulation of the transmittance at 2500 nm (between 51% and 8% at the film thickness of 88 nm) and the electrical resistivity (changed 350 times) at the transition temperature of 56-57 °C was achieved for the VO2 films synthesized using 50 µs voltage pulses when the crystallization of the thermochromic VO2(M1) phase was supported by the high-energy (up to 50 eV relative to ground potential) ions. Principles of this effective low-temperature deposition technique with a high application potential are presented.

  20. Low-temperature synthesis and characterization of TiO2 and TiO2-ZrO2 photocatalytically active thin films.

    Science.gov (United States)

    Maver, Ksenija; Stangar, Urska Lavrencic; Cernigoj, Urh; Gross, Silvia; Cerc Korosec, Romana

    2009-05-01

    Transparent TiO(2) and TiO(2)-ZrO(2) (molar ratio Zr/Ti = 0.1) thin films were produced by low-temperature sol-gel processing from nanocrystalline aqueous based solutions. The structural features and compositions of the films treated at room temperature, 100 degrees C and 500 degrees C were investigated by X-ray diffraction, X-ray photoelectron spectroscopy and thermal analysis. Addition of zirconia increased specific surface area (140-230 m(2) g(-1)) and hindered the growth of anatase crystallites, exhibiting a constant size of 6-7 nm in the whole temperature range. These significant changes with respect to pure TiO(2) in anatase crystalline form did not result in significantly and systematically different photocatalytic activity, which was evaluated in terms of aqueous pollutant degradation (azo-dye in water) and self-cleaning ability (fatty contaminant deposit). The films treated at only 100 degrees C showed excellent photocatalytic activity towards azo-dye degradation. Contact angle measurements of aged and contaminated surfaces revealed a fast or sharp hydrophilicity gain under UVA illumination. Accordingly, the results of this study confirmed the potential application of advantageous low-temperature films in water treatment as well as for self-cleaning surfaces.

  1. Solvent-Based Synthesis of Nano-Bi0.85Sb0.15 for Low-Temperature Thermoelectric Applications

    Science.gov (United States)

    Kaspar, K.; Fritsch, K.; Habicht, K.; Willenberg, B.; Hillebrecht, H.

    2017-01-01

    In this study we show a preparation method for nanostructured Bi0.85Sb0.15 powders via a chemical reduction route in a polyol medium, yielding material with particle sizes of 20-150 nm in scalable amounts. The powders were consolidated by spark plasma sintering (SPS) in order to maintain the nanostructure. To investigate influence of the sinter process, the powders were characterized by x-ray diffraction (XRD), energy dispersive x-ray spectroscopy (EDX), and scanning electron microscopy (SEM) measurements before and after SPS. Transport properties, Seebeck effect, and thermal conductivity were determined in the low temperature range below 300 K. The samples showed excellent thermal conductivity of 2.3-2.6 W/m × K at 300 K and Seebeck coefficients from -97 μV/K to -107 μV/K at 300 K with a maximum of -141 μV/K at 110 K, thus leading to ZT values of up to 0.31 at room temperature. The results show that Bi-Sb-alloys are promising materials for low-temperature applications. Our wet chemical approach gives access to scalable amounts of nano-material with increased homogeneity and good thermoelectric properties after SPS.

  2. In-situ reduction of a methanol synthesis catalyst in a three-phase slurry reactor

    Energy Technology Data Exchange (ETDEWEB)

    Sawant, A.; Ko, M.K.; Parameswaran, V.; Lee, S.; Kulik, C.J.

    1987-01-01

    A new method for the reduction of metal oxide catalysts (CuO, ZnO, Al/sub 2/O/sub 3/) has been developed for liquid phase methanol synthesis. The reducing agent is a 5% hydrogen in nitrogen mixture and the operation is carried out at 446.09 KPa. This method makes it possible to reduce finely crushed catalyst (-100 + 120 mesh) in a three phase slurry reactor. This method offers several advantages over methods in which the catalyst is reduced in a gas-solid contact mode and then slurried for use. The catalyst has been shown to be very effectively reduced and reaches its full production capacity after reduction.

  3. Dynamic Kinetics of Methanol Synthesis over a Commercial Copper-Based Catalyst

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    Adsorption, surface reaction and process dynamics on the surface of a commercial copper-based cata lyst for methanol synthesis from CO/CO2/H2 were systematically studied by means of temperature programmed desorption (TPD), tsmperature programmed surface reaction (TPSR), in-situ Fourier transform-inferred spec troscopy(FTIR) and stimulua-response techniques. As a part of results, an elementary step sequence was suggested and a group of ordinary differential equations (ODEs) for describing transient conversations relevant to all species on the catalyst surface and in the gas phase in a micro-fixed-bed reactor was derived. The values of the parameters referred to dynamic kinetics were estimated by fitting the solution of the ODEs with the transient response data obtained by the stimulus-response technique with a FTIR analyzer as an on-line detector.

  4. 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.

  5. Spectroscopy of Low Temperature Plasma

    CERN Document Server

    Ochkin, Vladimir N

    2009-01-01

    Providing an up-to-date overview on spectroscopical diagnostics of low temperature plasma Spectroscopy of Low Temperature Plasma covers the latest developments and techniques. Written by a distinguished scientist and experienced book author this text is applicable to many fields in materials and surface science as well as nanotechnology and contains numerous appendices with indispensable reference data.

  6. Microstructural characterization of Cu/ZnO/Al2O3 catalysts for the synthesis and steam reforming of methanol

    OpenAIRE

    2008-01-01

    Cu/ZnO/Al2O3 catalysts represent a versatile catalyst system for methanol chemistry, including the synthesis and steam reforming of methanol. Formally, the steam reforming of methanol is the reverse of methanol synthesis from CO2 and H2. In the present work a set of differently prepared Cu/ZnO/Al2O3 catalysts with a fixed composition of Cu/Zn/Al = 60:30:10 were investigated by in situ bulk techniques, X-ray diffraction, and X-ray absorption spectroscopy. Additionally, microscopic and morpholo...

  7. Hydrothermal synthesis of Pb(Zr0.52Ti0.48)O3 powders at low temperature and low alkaline concentration

    Indian Academy of Sciences (India)

    Zhong-Cheng Qiu; Jian-Ping Zhou; Gangqiang Zhu; Peng Liu; Xiao-Bing Bian

    2009-04-01

    Pb(Zr0.52Ti0.48)O3 (PZT) powders were prepared by hydrothermal method. The effects of experimental parameters, including Pb/(Zr, Ti) ratio, alkaline concentration, reaction temperature and time on the product powders were studied in detail. Pure PZT powders were synthesized at suitable experimental conditions and Raman spectra confirmed the PZT with a perovskite-type structure. The homogeneous PZT powders with cubic-shaped morphology were formed at alkaline concentration of 1.2 M after reacting at 230°C for 2 h. The pure PZT powders obtained at low temperature and low alkaline concentration were attributed to precursors, TiCl4, with high activity and mineralizer NaOH with small cation radius.

  8. Synthesis and characterization of SrCe0.95Y0.05O3-δ nano powders by low temperature combustion

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    Nanosized SrCe0.95Y0.05O3-δ powders with homogeneous composition were synthesized by the low temperature combustion process based on the Pechini method. A polymeric precursor sol was formed by using citric acid and ethylene glycol as the chelating agents of metal ions. The perovskite-type SrCe0.95Y0.05O3-δpowders with uniform shape and smaller than 25 nm in size were obtained through the combustion of the polymeric precursor sol at the existence of nitric acid and ammonium hydroxide. It was found that modulating the quantities of nitric acid and ammonium hydroxide could control the particle size, and the quantities of residue carbonate ions were also affected by the quantities of citric acid and ethylene glycol.

  9. Synthesis of SiO{sub 2}/β-SiC/graphite hybrid composite by low temperature hot filament chemical vapor deposition

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Zhikun; Bi, Kaifeng; Liu, Yanhong; Qin, Fuwen; Liu, Hongzhu [School of Physics and Optoelectronic Technology, Dalian University of Technology, Dalian 116024 (China); Bian, Jiming, E-mail: jmbian@dlut.edu.cn [School of Physics and Optoelectronic Technology, Dalian University of Technology, Dalian 116024 (China); Key Laboratory of Inorganic Coating Materials, Chinese Academy of Sciences, Shanghai 200050 (China); Zhang, Dong [New Energy Source Research Center of Shenyang Institute of Engineering, Shengyang 110136 (China); Miao, Lihua [School of Physics and Optoelectronic Technology, Dalian University of Technology, Dalian 116024 (China); Department of Computer and Mathematical Basic Teaching, Shenyang Medical College, Shenyan 110034 (China)

    2013-11-18

    β-SiC thin films were synthesized directly on graphite by hot filament chemical vapor deposition at low temperature. SiH{sub 4} diluted in hydrogen was employed as the silicon source, while graphite was functioned as both substrate and carbon source for the as-grown β-SiC films. X-ray diffraction and Fourier transform infrared analysis indicate that SiO{sub 2}/β-SiC/graphite hybrid composite was formed after post annealing treatment, and its crystalline quality can be remarkably improved under optimized annealing conditions. The possible growth mechanism was proposed based on in situ etching of graphite by reactive hydrogen radicals at the atomic level.

  10. Synthesis and Characterization of SnO2-TiO2 Nanocomposite with Rutile-phase via Hydrothermal Method at Low Temperature

    Institute of Scientific and Technical Information of China (English)

    WANG Yuan-rui; LI Wen-yan; ZHOU Bing; ZHAO Xu

    2013-01-01

    With Ti(SO4)2,SnCl4·5H2O and urea as raw materials,SnO2-TiO2 nanocomposites were synthesized via low temperature hydrothermal method at 80-100 ℃ in aqueous solutions.The morphologies of the products were altered systematically by varying the Ti/Sn molar ratio of the reactants,and rutile-phase particles were obtained with an average diameter of about 52.2 nm at a molar ratio of Ti/Sn=7.5.The surface composition of the composite was revealed by X-ray photoelectron spectroscopy(XPS) and X-ray diffraction(XRD) to be solely TiO2 with a rutile structure.This new composite material exhibits a high ultraviolet absorption capacity,and its photocatalytic activity for phenol oxidation is much lower than that of the commercial titania nanoparticles(P25).

  11. 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.

  12. 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.

  13. CO2 Activation and Methanol Synthesis on Novel Au/TiC and Cu/TiC Catalysts.

    Science.gov (United States)

    Vidal, Alba B; Feria, Leticia; Evans, Jaime; Takahashi, Yoshiro; Liu, Ping; Nakamura, Kenichi; Illas, Francesc; Rodriguez, José A

    2012-08-16

    Small Cu and Au particles in contact with a TiC(001) surface undergo a charge polarization that makes them very active for CO2 activation and the catalytic synthesis of methanol. The binding energy of CO2 on these systems is in the range of 0.6 to 1.1 eV, much larger than those observed on surfaces or nanoparticles of Cu and Au. Thus, in spite of the poor CO2 hydrogenation performance of Cu(111) and Au(111), the Cu/TiC(001) and Au/TiC(001) systems display a catalytic activity for methanol synthesis substantially higher than that of conventional Cu/ZnO catalysts. The turnover frequencies for methanol production on Cu/TiC(001) are 170-500 times much larger than on Cu(111). The present study moves away from the typical approach of using metal/oxide catalysts for the synthesis of methanol via CO2 hydrogenation. This work shows that metal carbides can be excellent supports for enhancing the ability of noble metals to bond and activate CO2.

  14. Effect of Titanium on Methanol Synthesis from CO2 Hydrogenation over Cu/γ-Al2O3

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    Titanium-modified g-alumina supported CuO catalyst has been prepared and used to methanol synthesis from CO2 hydrogenation. The addition of Ti to the CuO/γ-Al2O3 catalyst made the copper in the catalyst exist in much smaller crystallites. The effect of the loading of Ti on the activity and selectivity to methanol from CO2 hydrogenation was investigated. The activity was found to increase with the increasing of surface area of metallic copper, but it is not a linear relationship.

  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 of biodiesel from vegetable oil with methanol catalyzed by Li-doped magnesium oxide catalysts

    Energy Technology Data Exchange (ETDEWEB)

    Wen, Zhenzhong; Yu, Xinhai; Tu, Shan-Tung [School of Mechanical and Power Engineering, East China University of Science and Technology, Meilong Rd. 130, Shanghai 200237 (China); Yan, Jinyue [School of Sustainable Development of Society and Technology, Maelardalen University, SE-721 23 Vaesteraas (Sweden); School of Chemical Science and Engineering, Royal Institute of Technology, Stockholm, SE-100 44 Stockholm (Sweden); Dahlquist, Erik [School of Sustainable Development of Society and Technology, Maelardalen University, SE-721 23 Vaesteraas (Sweden)

    2010-03-15

    The preparation of a Li-doped MgO for biodiesel synthesis has been investigated by optimizing the catalyst composition and calcination temperatures. The results show that the formation of strong base sites is particularly promoted by the addition of Li, thus resulting in an increase of the biodiesel synthesis. The catalyst with the Li/Mg molar ratio of 0.08 and calcination temperature of 823 K exhibits the best performance. The biodiesel conversion decreases with further increasing Li/Mg molar ratio above 0.08, which is most likely attributed to the separated lithium hydroxide formed by excess Li ions and a concomitant decrease of BET values. In addition, the effects of methanol/oil molar ratio, reaction time, catalyst amount, and catalyst stability were also investigated for the optimized Li-doped MgO. The metal leaching from the Li-doped MgO catalysts was detected, indicating more studies are needed to stabilize the catalysts for its application in the large-scale biodiesel production facilities. (author)

  17. Isobutanol-methanol mixtures from synthesis gas. Quarterly technical progress report, 1 January--31 March 1996

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1996-04-20

    A series of CuMgCeO{sub x} catalysts have been prepared. Range of Cu dispersion, determined by N{sub 2}O titration, was 19-48% and are among the highest reported in the literature for Cu-based methanol and higher alcohol synthesis catalysts. Kinetics of MeOH and EtOH coupling reactions on Cu/ZnO and K-Cu/MgO/CeO{sub 2} catalysts indicate that Cu promotes alcohol dehydrogenation. Acetaldehyde is a reactive intermediate. High-pressure isobutanol synthesis studies have been carried out on K- and Cs-promoted Cu/MgO/CeO{sub 2} catalysts. The K promoter is more active than Cs for CO conversion, but the Cs promoter activates the C{sub 1} to C{sub 2} step more effectively. Catalysts with high alkali loading resulted in low conversions. Temperature programmed surface reaction studies of MeOH, EtOH, and acetaldehyde on MgO/CeO{sub 2}-based Cu catalysts show evolution of acetone, crotonaldehyde, methyl ethyl ketone, H2, carbon oxides. Neither EtOH nor acetaldehyde produces propionaldehyde or 1- propanol, suggesting that these C{sub 3} species can only form via reactions involving C{sub 1} and C{sub 2} oxygenate species.

  18. Low-temperature synthesis of zeolite from perlite waste — Part I: review of methods and phase compositions of resulting products

    Science.gov (United States)

    Król, Magdalena; Morawska, Justyna; Mozgawa, Włodzimierz; Pichór, Waldemar

    2014-09-01

    In this paper a review of the recent studies on the synthesis of zeolites from expanded perlite under hydrothermal conditions is presented. Attention is paid to possible outcomes of synthesis from low cost glass material, such as perlite. The study also investigates the phase composition of zeolitic materials obtained by modification of by-product derived from an expanded perlite production process. The synthesis was made using the hydrothermal method with sodium hydroxide under autogenous pressure at a temperature below 100 °C for 1 to 72 h. It was possible to obtain a zeolitic material at a temperature as low as 60 °C using 4.0 M NaOH. The X-ray diffraction pattern showed the biggest peak intensity of zeolite X with 4.0 M NaOH at the temperature of 70 °C. During synthesis at higher temperature zeolite Na-P1 (with 3.0 M NaOH at 90 °C) and hydroxysodalite (with 5.0 M NaOH at 90 °C) were obtained.

  19. Solid State Synthesis of Nanometer ZnO in Low Temperature%ZnO纳米棒的低温固相合成

    Institute of Scientific and Technical Information of China (English)

    薛晓楠

    2012-01-01

    以无水ZnSO4与NaOH为原料,在红外灯照射下,通过低温固态化学反应路线制备ZnO纳米棒。通过XRD、XPS和TEM对制得的ZnO纳米棒的结构和形貌进行了分析。研究表明产物的形貌和尺寸可通过调节实验条件(如原料比、有无照射、盐的类型等)加以控制。%ZnO nanorods had been synthesized via a solid -state reaction route between anhydrous ZnSO4 and NaOH under the irradiation of the 250 W IR lamp at relatively low temperature. The structure and shape of ZnO nanorods were analysed by XRD, XPS and TEM. The results showed that the size and morphology of the resulted products could be controlled through adjusting the reaction conditions, including Zn2+/OH-ratio,with and without the irradiation of IR lamp and the kind of zinc salt.

  20. Low temperature synthesis of radio frequency magnetron sputtered gallium and aluminium co-doped zinc oxide thin films for transparent electrode fabrication

    Science.gov (United States)

    Muchuweni, E.; Sathiaraj, T. S.; Nyakotyo, H.

    2016-12-01

    Gallium and aluminium co-doped zinc oxide (GAZO) thin films were prepared on glass substrates at low temperatures by radio frequency (rf) magnetron sputtering and their physical properties were investigated. All films possessed a hexagonal wurtzite crystal structure with a strong growth orientation along the (0 0 2) c-axis. The (0 0 2) peak intensity and mean crystallite size increased with substrate temperature from room temperature (RT) to 75 °C and then decreased at 100 °C, indicating an improvement in crystallinity up to 75 °C and its deterioration at 100 °C. Scanning electron microscopy (SEM) micrographs revealed the strong dependency of surface morphology on substrate temperature and energy dispersive spectroscopy (EDS) confirmed the incorporation of Ga and Al into the ZnO films. All films exhibited excellent transmittances between 85 and 90% in the visible region and their optical band gap increased from 3.22 eV to 3.28 eV with substrate temperature. The Urbach energy decreased from 194 meV to 168 meV with increasing substrate temperature, indicating a decrease in structural disorders which was consistent with X-ray Diffraction (XRD) analysis. Films deposited at 75 °C exhibited the lowest electrical resistivity (2.4 Ωcm) and highest figure of merit (7.5 × 10-5 Ω-1), proving their potential as candidates for transparent electrode fabrication.

  1. Simple synthesis and size-dependent surface-enhanced Raman scattering of Ag nanostructures on TiO2 by thermal decomposition of silver nitrate at low temperature.

    Science.gov (United States)

    Wang, Ruey-Chi; Gao, Yong-Siang; Chen, Shu-Jen

    2009-09-16

    A low-temperature dry-process was proposed to synthesize silver nanoparticles, nanorods, and nanoplates on TiO(2) films via thermal decomposition of silver nitrate. X-ray diffraction (XRD) shows only silver crystals were synthesized on the substrate without other byproducts remaining. Scanning electron microscopy (SEM) and transmission electron microscopy (TEM) reveal the Ag nanoparticles are single-crystalline face-centered cubic (FCC) structures and their average diameters decrease from 100 to 15 nm with the increase in distance from the source, which corresponds to a decrease of substrate temperature from 350 to 110 degrees C. The Ag nanorods are also single-crystalline FCC structures growing along the [110] direction with diameter and length around 40 and 500 nm, respectively. The morphology of silver nanostructures could be adjusted by varying the working pressure as well as the roughness of the substrates. An obvious size-dependent SERS effect on the TiO(2) substrate with silver nanoparticles was observed for the first time. The enhancement factor increases as the size of the Ag nanoparticles decreases, which is attributed to the increase of hot spots. In addition, fractional brookite in the anatase films could be detected only after being loaded with Ag nanoparticles, which demonstrates the application of SERS in detecting fractional and important features of semiconductors.

  2. Effect of Oxide Coating on Performance of Copper-Zinc Oxide-Based Catalyst for Methanol Synthesis via Hydrogenation of Carbon Dioxide

    Directory of Open Access Journals (Sweden)

    Tetsuo Umegaki

    2015-11-01

    Full Text Available The effect of oxide coating on the activity of a copper-zinc oxide–based catalyst for methanol synthesis via the hydrogenation of carbon dioxide was investigated. A commercial catalyst was coated with various oxides by a sol-gel method. The influence of the types of promoters used in the sol-gel reaction was investigated. Temperature-programmed reduction-thermogravimetric analysis revealed that the reduction peak assigned to the copper species in the oxide-coated catalysts prepared using ammonia shifts to lower temperatures than that of the pristine catalyst; in contrast, the reduction peak shifts to higher temperatures for the catalysts prepared using L(+-arginine. These observations indicated that the copper species were weakly bonded with the oxide and were easily reduced by using ammonia. The catalysts prepared using ammonia show higher CO2 conversion than the catalysts prepared using L(+-arginine. Among the catalysts prepared using ammonia, the silica-coated catalyst displayed a high activity at high temperatures, while the zirconia-coated catalyst and titania-coated catalyst had high activity at low temperatures. At high temperature the conversion over the silica-coated catalyst does not significantly change with reaction temperature, while the conversion over the zirconia-coated catalyst and titania-coated catalyst decreases with reaction time. From the results of FTIR, the durability depends on hydrophilicity of the oxides.

  3. Sensors for low temperature application

    Science.gov (United States)

    Henderson, Timothy M.; Wuttke, Gilbert H.

    1977-01-01

    A method and apparatus for low temperature sensing which uses gas filled micro-size hollow glass spheres that are exposed in a confined observation area to a low temperature range (Kelvin) and observed microscopically to determine change of state, i.e., change from gaseous state of the contained gas to condensed state. By suitable indicia and classification of the spheres in the observation area, the temperature can be determined very accurately.

  4. Low temperature relations in QCD

    CERN Document Server

    Agasian, N O

    2002-01-01

    In this talk I discuss the low temperature relations for the trace of the energy-momentum tensor in QCD with two and three quarks. It is shown that the temperature derivatives of the anomalous and normal (quark massive term) contributions to the trace of the energy-momentum tensor in QCD are equal to each other in the low temperature region. Leading corrections connected with $\\pi\\pi$-interactions and thermal excitations of $K$ and $\\eta$ mesons are calculated.

  5. Effect of cerium incorporation into zirconia on the activity ofCu/ZrO2 for methanol synthesis via CO hydrogenation

    Energy Technology Data Exchange (ETDEWEB)

    Pokrovski, Konstantin A.; Rhodes, Michael D.; Bell, Alexis T.

    2005-08-24

    The effects of Ce incorporation into ZrO2 on the catalyticperformance of Cu/ZrO2 for the hydrogenation of CO have beeninvestigated. A Ce0.3Zr0.7O2 solid solution was synthesized by forcedhydrolysis at low pH. After calcination at 873 K, XRD and Ramanspectroscopy characterization indicated that the Ce0.3Zr0.7O2 had a t''crystal structure. 1.2 wt percent Cu/Ce0.3Zr0.7O2 exhibited H2consumption peaks at low temperature (<473 K) during H2-TPRindicating a significant fraction (~; 70 percent) of Ce4+ is reduced toCe3+. 1.2 wt percent Cu/Ce0.3Zr0.7O2 is 2.7 times more active formethanol synthesis than 1.2 wt percent Cu/m-ZrO2 at 3.0 MPa attemperatures between 473 and 523 K and exhibits a higher selectivity tomethanol. In-situ infrared spectroscopy shows that, analogous toCu/m-ZrO2, the primary surface species on Cu/Ce0.3Zr0.7O2 during COhydrogenation are formate and methoxide species. A shift in the bandposition of the bridged methoxide species indicated that some of thesegroups were bonded to both Zr4+ and Ce3+ cations. For both catalysts, therate-limiting step for methanol synthesis is the reductive elimination ofmethoxide species. The higher rate of methanol synthesis onCu/Ce0.3Zr0.7O2 relative to Cu/m-ZrO2 was primarily due to a ~; 2.4 timeshigher apparent rate constant, kapp, for methoxide hydrogenation, whichis attributed to the higher surface concentration of H atoms on theformer catalyst. The increased capacity of the Ce-containing catalyst isattributed to interactions of H atoms with Ce-O pairs present at thesurface of the oxide phase.

  6. 非水解凝胶化工艺对低温合成硅酸锆的影响%Effect of Non-Hydrolytic Gelation Process on Synthesis of Zircon at Low Temperature

    Institute of Scientific and Technical Information of China (English)

    江伟辉; 张缇; 朱庆霞; 刘健敏

    2011-01-01

    以工业纯无水ZrCl4、正硅酸乙酯(Si(OC2H5)4)为前驱体,LiF为矿化剂,通过非水解溶胶-凝胶法低温合成出硅酸锆粉体.应用热重-差热分析、X射线衍射和透射电子显微镜等研究了不同非水解凝胶化工艺对低温合成硅酸锆的影响.结果表明:通过容弹工艺无法低温合成硅酸锆;采用回流工艺虽然能低温合成出硅酸锆粉体,但所制得的硅酸锆晶体轮廓不清、发育较差.只有将回流和容弹工艺相结合才能在700℃合成出充分发育的四方柱状硅酸锆晶体.%Zircon powder was synthesized at a low temperature via a non-hydrolytic sol-gel route, using zirconium tetrachloride and tetraethoxysilane as precursors, lithium fluoride as a mineralizer. The effect of the nonhydrolytic gelation process on the zircon synthesis at a low temperature was investigated by thermogravimetry-differential thermal analysis, X-ray diffraction and transmission electron microscope. The results indicate that the zircon can not be synthesized by a direct solvothermal treatment at a low temperature, and the direct reflux process can result in the formation of the zircon with fuzzy crystal configuration due to the incomplete crystal growth. The zircon particles with the tetragonal columnar shape can be synthesized by the combined processes of direct solvothermal treatment and direct reflux process at 700 ℃.

  7. 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, decompositio

  8. 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, decompositio

  9. Rapid Microwave-Assisted Solvothermal Synthesis of Non-Olivine Cmcm Polymorphs of LiMPO4 (M = Mn, Fe, Co, and Ni) at Low Temperature and Pressure.

    Science.gov (United States)

    Assat, Gaurav; Manthiram, Arumugam

    2015-10-19

    Lithium transition-metal phosphates, LiMPO4 (M = Mn, Fe, Co, and Ni), have attracted significant research interest over the past two decades as an important class of lithium ion battery cathode materials. However, almost all of the investigations thus far have focused on the olivine polymorph that exists in the orthorhombic Pnma space group. In this study, a distinct orthorhombic but non-olivine polymorph of LiMPO4, described by a Cmcm space group symmetry, has been synthesized with M = Mn, Fe, Co, and Ni. Of these, LiMnPO4 in the Cmcm space group is reported for the first time. A rapid microwave-assisted solvothermal (MW-ST) heating process with tetraethylene glycol (TEG) as the solvent and transition-metal oxalates as precursors facilitates the synthesis of these materials. The peak reaction temperatures and pressures were below 300 °C and 30 bar, respectively, which are several orders of magnitude lower than those of the previously reported high-pressure (gigapascals) method. X-ray diffraction (XRD) confirms the crystal structure with the Cmcm space group, and scanning electron micrographs indicate a submicrometer thin platelet-like morphology. The synthesis process conditions have been optimized to obtain impurity-free samples with the correct stoichiometry, as characterized by XRD and inductively coupled plasma-optical emission spectroscopy (ICP-OES). Upon heat treatment to higher temperatures, an irreversible transformation of the metastable Cmcm polymorphs into olivine is observed by XRD and Fourier transform infrared spectroscopy. Although the electrochemical activity of these polymorphs as lithium ion cathodes turns out to be poor, the facile synthesis under mild conditions has permitted easy access to these materials in a nanomorphology, some of which were not even possible before.

  10. 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.

  11. Influence of Reaction Conditions on Methanol Synthesis and WGS Reaction in the Syngas-to-DME Process

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    A series of CuO-ZnO catalysts (with different Cu/Zn molar ratios) were prepared, and evaluated under the reaction conditions of syngas-to-dimethyl ether (DME) with three sorts of feed gas and different space velocity. The catalysts were characterized by X-ray diffraction (XRD) and temperatureprogrammed reduction (TPR). The experiment results showed that the reaction conditions of syngas-to-DME process greatly affected the methanol synthesis and WGS reaction. The influence caused by Cu/Zn molar ratio was quite different on the two reactions; increasing of percentage of CO2 in feed gas was unfavorable for catalyst activity, and also inhibited both reactions; enhancement of reaction space velocity heavily influenced the performance of the catalyst, and the benefits were relatively less for methanol synthesis than for the WGS reaction.

  12. Adaptation o Cu/ZnO/Al2O3 to Temperature Change in Methanol Synthesis from CO2 Hydrogenation

    Institute of Scientific and Technical Information of China (English)

    JialinTao; Ki-WonJun; 等

    2002-01-01

    The induction behavior in CO2 hydrogenation was studied by varying the reaction temperature to investigate the adaptation of the Cu/ZnO/Al2O3 catalyst to the temperature change,The results indicated that a used catalyst had a tendency to keep the last running state in new reaction conditions for MeOH formation,and that this tendency was related to the difference in Cu/Cun+ ration caused by CO2 and CO produced at different reaction temperatures,However,the reverse water-gas shift reaction (BWGS) induced at four temperatures was completely different from that of methanol synthesis,It implied that the two so-called competitive reactions in CO2+H2,RWGS and methanol synthesis,have different, active centers.

  13. Adaptation of Cu/ZnO/Al2O3 to Temperature Change in Methanol Synthesis from CO2 Hydrogenation

    Institute of Scientific and Technical Information of China (English)

    Jialin Tao; Ki-Won Jun; Kyu-Wan Lee

    2002-01-01

    The induction behavior in CO2 hydrogenation was studied by varying the reaction temperatureto investigate the adaptation of the Cu/ZnO/Al2O3 catalyst to the temperature change. The resultsindicated that a used catalyst had a tendency to keep the last running state in new reaction conditionsfor MeOH formation, and that this tendency was related to the difference in Cu/Cun+ ratio caused byCO2 and CO produced at different reaction temperatures. However, the reverse water-gas shift reaction(RWGS) induced at four temperatures was completely different from that of methanol synthesis. It impliedthat the two so-called competitive reactions in CO2+H2, RWGS and methanol synthesis, have differentactive centers.

  14. 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

  15. Synthesis and characterization of PbSe nanoparticles obtained by a colloidal route using Extran as a surfactant at low temperature

    Science.gov (United States)

    Romano-Trujillo, R.; Rosendo, E.; Ortega, M.; Morales-Sánchez, A.; Gracia, J. M.; Díaz, T.; Nieto, G.; García, G.; Luna-López, J. A.; Pacio, M.

    2012-05-01

    Lead selenide nanoparticles (PbSe NPs) have been obtained through an easy and low cost route using colloidal synthesis in aqueous solution. The synthesis was carried out at room temperature using Extran (Na5P3O10, NaOH and H2O) as surfactant. Hydrochloric acid (HCl) was used to eliminate the generated by-products. The size of PbSe NPs was varied by changing the Pb:Se molar concentration. The PbSe NPs were characterized by powder x-ray diffraction (XRD), scanning electron microscopy (SEM), energy dispersive x-ray analysis (EDAX), high-resolution transmission electron microscopy (HRTEM) and Raman spectroscopy. The XRD measurements showed that the PbSe NPs have the face-centered cubic phase structure. The crystal size was found to be between 14 and 20 nm as calculated from the XRD patterns and these values were corroborated with SEM and TEM. Additionally, HRTEM micrographs showed crystalline planes at (200), (220) and (111) of the PbSe NPs, in agreement with the XRD results.

  16. Low temperature synthesis of low thermionic work function (La{sub x}Ba{sub 1−x})B{sub 6}

    Energy Technology Data Exchange (ETDEWEB)

    Hasan, M.M., E-mail: Muhammad.Hasan@uon.edu.au; Cuskelly, D.; Sugo, H.; Kisi, E.H.

    2015-07-05

    Highlights: • The mixed boride La{sub x}Ba{sub 1−x}B{sub 6} was successfully produced using a boron carbide method. • Following synthesis samples sintered at 1950 °C yielded ∼85% (wt%) (La{sub 0.31}Ba{sub 0.69})B{sub 6}. • The Richardson work function for this boride mixture was found to be only 1.03 eV. - Abstract: This study presents investigations of the microstructure, morphology and emission properties of the promising thermionic material (La{sub x}Ba{sub 1−x})B{sub 6}. The material was synthesised by solid-state reaction without post-synthesis purifications. Powder X-ray diffraction revealed that samples prepared at a temperature ⩾1500 °C had formed a significant proportion of solid solution (above 54 mass%). Subsequent sintering at 1950 °C caused the formation of a mixture of three solid solutions with the dominant phase being (La{sub 0.31}Ba{sub 0.69})B{sub 6} ∼85% (by mass). The Richardson work function and emission constant for this boride mixture were found to be 1.03 eV and 8.44 × 10{sup −6} A cm K{sup −2} respectively.

  17. Isobutanol-methanol mixtures from synthesis gas. Quarterly report, July 1 - September 30, 1996

    Energy Technology Data Exchange (ETDEWEB)

    Iglesia, E.

    1996-12-01

    A series of CuMgCeO{sub x} catalysts have been prepared by coprecipitating the corresponding metal nitrates with a mixed solution of potassium carbonate and potassium hydroxide. The bulk composition of the catalyst has been measured by atomic absorption (AA) analysis and the Cu dispersion has been determined by N{sub 2}O titration at 90 {degrees}C. CeO{sub x} does not contribute to the measured copper dispersion in K-CuO{sub 0.5}Mg{sub 5}CeO{sub x} samples and the high dispersion value indeed reflects the presence of Cu metal small crystallites. Kinetic studies of methanol and propionaldehyde coupling reactions on K-Cu/MgO/CeO{sub 2} and MgO/CeO{sub 2} catalysts indicate that Cu enhances the rates of alcohol dehydrogenation. High-pressure isobutanol synthesis from CO/H{sub 2} has been studied on CuO{sub 0.5}Mg{sub 5}O{sub x} catalysts at 593 K and 4.5 MPa. CuO{sub 0.5}Mg{sub 5}O{sub x} catalysts show high hydrocarbon and low isobutanol selectivities compared to K-CuO{sub 0.5}Mg{sub 5}CeO{sub x}, suggesting the presence of residual acidity in CuO{sub 0.5}Mg{sub 5}O{sub x}.

  18. Effects of carbon dioxide, water and thermal aging on the methanol synthesis catalyst

    Energy Technology Data Exchange (ETDEWEB)

    Sawant, A.V.

    1987-01-01

    The effects of chemical environment and thermal aging on the methanol synthesis catalyst were studied. It was determined that the copper in the active copper-zinc-alumina catalyst existed in its zero valence state. It was also determined that under high partial pressures of carbon dioxide in the reaction gases, zinc carbonate was formed in the catalyst. The effects of water and carbon dioxide on the catalyst structure were studied. Experiments were performed at different temperatures and pressures to study this phenomenon. Atomic absorption spectrometry was used to analyze the water. X-ray powder diffraction and electron dot map analysis were used to study the changes in the catalyst. A copper-zinc compound, Rosalite was found t be present in the catalysts. Catalysts were thermally aged and the changes in the catalyst crystallite size distribution were measured. Chemical environment was shown to play a dominant role in this change. Catalysts were subjected to oxidation and reduction and a redispersion of the copper in the catalyst was successfully obtained.

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

    Science.gov (United States)

    Zhao, Qi; Zhang, Geng; Xu, Guangran; Li, Yingjun; Liu, Baocang; Gong, Xia; Zheng, Dafang; Zhang, Jun; Wang, Qin

    2016-12-01

    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-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.

  20. 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.

  1. Environmental life cycle assessment (E-LCA) applied to the synthesis of methanol and dimethylcarbonate

    Energy Technology Data Exchange (ETDEWEB)

    Aresta, M.; Caroppo, A.; Dibenedetto, A.; Magarelli, A. [University of Bari, Bari (Italy). METEA Research Center

    2001-07-01

    Environmental Life Cycle Analysis, ELCA, has been used for assessing the environmental impact of the synthesis of methanol using either carbon monoxide or recovered carbon dioxide. The basic case considered carbon monoxide generated by the water gas reaction or steam reforming of natural gas and CO{sub 2} as produced by WGSR or recovered from power plant flue gases. The following impact categories were considered: greenhouse effect; ozone layer depletion; acidification; nitrification; and photochemical oxidant formation. The best mixing for the minimisation of both the emissions and hydrogen consumption has been shown to be a 3:1 molar ratio of CO and CO{sub 2}. The preliminary results of a cost analysis and energy assessment, mixing steam and dry reforming, are also presented. The same methodology has been used for the assessment of three different synthetic pathways for dimethylcarbonate, including the one based on the use of phosgene, a process now on stream that has a high environmental impact. 5 refs., 2 figs., 5 tabs.

  2. Synthesis of thoria nano-particles at low temperature through base electrogeneration on steel 316L surface: Effect of current density

    Science.gov (United States)

    Yousefi, Taher; Torab-Mostaedi, Meisam; Mobtaker, Hossein Ghasemi; Keshtkar, Ali Reza

    2016-10-01

    The strategy developed in this study, offers significant advantages (simplicity and cleanness of method and also a product purity and new morphology of the product) over the conventional routes for the synthesis of ThO2 nanostructure. The effect of current density on morphology was studied. The synthesized powder was characterized by means of Powder X-ray Diffraction (PXRD), Transmission Electron Microscopy (TEM, Phillips EM 2085) Brunauer-Emmett-Teller (BET) and Fourier Transform Infrared (FT-IR) spectroscopy. The results show that the current density has a great effect on the morphology of the samples. The average size of the particles decreases as the applied current density increases and the average size of the samples decreases from 50 to 15 nm when the current density increases from 2 to 5 mA cm-2.

  3. Low temperature synthesis of carbon-wrapped CuO synthesized without using a conventional carbon source for Li ion battery application

    Science.gov (United States)

    Saravanan, M.; Nair, Shantikumar V.; Rai, Alok Kumar

    2017-10-01

    Carbon-wrapped CuO is synthesized by a facile pyro-synthesis method without using a conventional carbon source to overcome the capacity fading issue of CuO nanoparticles. The microstructure analysis shows that the sample is fully wrapped by a carbon layer. The resultant carbon-wrapped CuO nanocomposite as an anode exhibits high reversible capacity with excellent cycling stability (437.1 mAh/g at 0.25 C and 365.2 mAh/g at 1.0 C after 100 cycles) and good rate capability. It is believed that the synergistic effect of CuO and carbon is responsible for the enhanced electrochemical performance of the nanocomposite electrode.

  4. Certification testing at low temperatures

    Energy Technology Data Exchange (ETDEWEB)

    Noss, P.W. [Packaging Technology, Tacoma, WA (United States); Ammerman, D.J. [Sandia National Labs., Albuquerque, NM (United States)

    2004-07-01

    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.

  5. Low temperature aluminum soldering analysis

    Energy Technology Data Exchange (ETDEWEB)

    Peterkort, W.G.

    1976-09-01

    The investigation of low temperature aluminum soldering included the collection of spread factor and dihedral angle data for several solder alloys and a study of flux effects on aluminum. Selected solders were subjected to environmental tests and evaluated on the basis of tensile strength, joint resistance, visual appearance, and metallurgical analysis. A production line method for determining adequate flux removal was developed.

  6. Low-temperature magnetic refrigerator

    Science.gov (United States)

    Barclay, John A.

    1985-01-01

    The disclosure is directed to a low temperature 4 to 20 K. refrigeration apparatus and method utilizing a ring of magnetic material moving through a magnetic field. Heat exchange is accomplished in and out of the magnetic field to appropriately utilize the device to execute Carnot and Stirling cycles.

  7. Microwave-assisted low temperature synthesis of sodium zirconium phosphate (NZP) and the leachability of some selected fission products incorporated in its structure - A case study of leachability of cesium

    Indian Academy of Sciences (India)

    A H Naik; S B Deb; A B Chalke; M K Saxena; K L Ramakumar; V Venugopal; S R Dharwadkar

    2010-01-01

    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. Three selected fission products, namely, Cesium, Strontium and Tellurium were introduced (substituted) in the NZP matrix during its synthesis at 450°C. Leaching studies were carried out on the fission product substituted NZP sintered at 1000°C, in pure de-ionized water and 80% saturated brine solution at the ambient temperatures of 30°C and 90°C for four weeks. The major part of leaching in all the cases was observed in the first week. The extent of leaching after four weeks was found not exceeded from 12 to 15% of the elements substituted in NZP, which later became negligibly small. The effect of temperature and the nature of leachant on the leaching rate did not indicate any systematic trend. The EDX analysis of the surfaces of the leached NZP pellets showed that the leaching of the dopants is limited mainly to the surface region of the sintered pellets.

  8. Low Temperature Synthesis and Characterization of Li1.2-y NayV3O8(0≤y≤1.2) from V2O5 Gel

    Institute of Scientific and Technical Information of China (English)

    谢静刚; 肖婕; 等

    2003-01-01

    Without overnight heating and stirring,Li1.2V3O8 and its analogs Li1.2-y NayV3O8(0≤y≤1.2) were successfully synthesized by adding mixed solution of LiOH and NaVO3 to V2O5 gel and dehydrating the prepared gel in 150-350℃.The simplicity awards this synthesis process superiority over other low temperature synthesis routes when mass production is concerned.TG-DTA,XRD and TEM experiments were carried out for physical characterization.By galvanostatic charge-discharge and cyclic voltammetry tests,these products showed better electrochemical performance than high temperature products as cathode active materials in secondary lithium batteries.After treatment of Li1.2V3O8 at 250℃,it exhibited a capacity of 350mAh/g when cycled at current rate of about 60 mA/g over the voltage range of 3.8-1.7V vs,Li+/Li.The influence of partial substitution of Li by Na was also extensively studied.

  9. 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).

  10. Simultaneous production and utilization of methanol for methyl formate synthesis in a looped heat exchanger reactor configuration

    Institute of Scientific and Technical Information of China (English)

    A.Goosheneshin; R.Maleki; D.Iranshahi; M.R.Rahimpour; A.Jahanmiri

    2012-01-01

    In this investigation,a novel thermally coupled reactor (TCR) containing methyl formate (MF) production in the endothermic side and methanol synthesis in the exothermic side has been investigated.The interesting feature of this TCR is that productive methanol in the exothermic side could be recycled and used as feed of endothermic side for MF synthesis.Other important advantages of the proposed system are high production rates of hydrogen and MF.The configuration consists of two thermally coupled concentric tubular reactors.In these coupled reactors,autothermal system is obtained within the reactor.A steady-state heterogeneous model is used for simulation of the coupled reactor.The proposed model has been utilized to compare the performance of TCR with the conventional methanol reactor (CMR).Noticeable enhancement can be obtained in the performance of the reactors.The influence of operational parameters is studied on reactor performance.The results show that coupling of these reactions could be feasible and beneficial.Experimental proof-of-concept is required to validate the operation of the novel reactor.

  11. Efficiency Assessment of Using Flammable Compounds from Water Treatment and Methanol Production Waste for Plasma Synthesis of Iron-Containing Pigments

    OpenAIRE

    Shekhovtsova, Anastasia; Karengin, Aleksander Grigorievich

    2016-01-01

    This article describes the possibility of applying the low-temperature plasma for obtaining iron-containing pigments from water purification and flammable methanol production waste. In this paper were calculated combustion parameters of water-saltorganic compositions (WSOC) with different consists. Authors determined the modes of energy- efficient processing of the previously mentioned waste in an air plasma. Having considered the obtained results there were carried out experiments with flamm...

  12. Low Temperature Emissivity Measurement System

    Directory of Open Access Journals (Sweden)

    Jignesh A. Patel

    2014-05-01

    Full Text Available The emissivity of a material is the relative ability of its surface to emit energy by radiation. It is the ratio of energy radiated by a particular material to energy radiated by a black body at the same temperature. Knowledge about the low temperature emissivity of materials and coatings can be essential to the design of fusion cryoplants and in the thermal modeling for space satellite missions. The emittance of materials at cryogenics temperatures often cannot be predicted from room temperature data, but for computing radiative loads and infrared backgrounds this cryogenic data is often required. Measurement of the cryogenic emissivity of a highly reflective surface is a significant challenge: little thermal power is radiated from the sample, and the background radiation. However some researchers have measured emissivity at various low temperature ranges. Present work reports, the various emissivity measurement setup and their considerations.

  13. Sustained Low Temperature NOx Reduction

    Energy Technology Data Exchange (ETDEWEB)

    Zha, Yuhui

    2017-04-05

    Increasing regulatory, environmental, and customer pressure in recent years led to substantial improvements in the fuel efficiency of diesel engines, including the remarkable breakthroughs demonstrated through the Super Truck program supported by the U.S. Department of Energy (DOE). On the other hand, these improvements have translated into a reduction of exhaust gas temperatures, thus further complicating the task of controlling NOx emissions, especially in low power duty cycles. The need for improved NOx conversion over these low temperature duty cycles is also observed as requirements tighten with in-use emissions testing. Sustained NOx reduction at low temperatures, especially in the 150-200oC range, shares some similarities with the more commonly discussed cold-start challenge, however poses a number of additional and distinct technical problems. In this project we set a bold target of achieving and maintaining a 90% NOx conversion at the SCR catalyst inlet temperature of 150oC. The project is intended to push the boundaries of the existing technologies, while staying within the realm of realistic future practical implementation. In order to meet the resulting challenges at the levels of catalyst fundamentals, system components, and system integration, Cummins has partnered with the DOE, Johnson Matthey, and Pacific Northwest National Lab and initiated the Sustained Low-Temperature NOx Reduction program at the beginning of 2015. Through this collaboration, we are exploring catalyst formulations and catalyst architectures with enhanced catalytic activity at 150°C; opportunities to approach the desirable ratio of NO and NO2 in the SCR feed gas; options for robust low-temperature reductant delivery; and the requirements for overall system integration. The program is expected to deliver an on-engine demonstration of the technical solution and an assessment of its commercial potential. In the SAE meeting, we will share the initial performance data on engine to

  14. Synthesis of silver nanoparticles using methanol and dichloromethane extracts of Pulicaria gnaphalodes (Vent.) Boiss. aerial parts.

    Science.gov (United States)

    Chitsazi, Mohammad Reza; Korbekandi, Hassan; Asghari, Gholamreza; Bahri Najafi, Rahim; Badii, Akbar; Iravani, Siavash

    2016-01-01

    The objectives were to study the potential of Pulicaria gnaphalodes (Vent.) Boiss. aerial parts in production of nanoparticles and the effect of the extraction solvent on the produced nanoparticles. Methanol and dichloromethane extracts were prepared by percolation of the plant powder. Both the extracts of P. gnaphalodes (Vent.) Boiss. successfully produced small and polydispersed nanoparticles with low aggregates in early hours of the biotransformation. Methanol extract produced spherical and many single nanoparticles, whereas dichloromethane produced porous polyhedral and more aggregated nanoparticles. Methanol extract of this plant seems to be quiet useful for industrial scale production of nanoparticles.

  15. Insight into methanol synthesis from CO2 hydrogenation on Cu(111): Complex reaction network and the effects of H2O

    Energy Technology Data Exchange (ETDEWEB)

    Zhao, Yafan; Yang, Yong; Mims, Charles A.; Peden, Charles HF; Li, Jun; Mei, Donghai

    2011-05-31

    Methanol synthesis from CO2 hydrogenation on supported Cu catalysts is of considerable importance in the chemical and energy industries. Although extensive experimental and theoretical efforts have been carried out in the past decades, the most fundamental questions such as the reaction mechanisms and the key reaction intermediates are still in debate. In the present work, a comprehensive reaction network for CO2 hydrogenation to methanol on Cu(111) was studied using periodic density functional theory (DFT) calculations. All of the elementary reaction steps in the reaction network were identified in an unbiased way with the dimer method. Our calculation results show that methanol synthesis from direct hydrogenation of formate on Cu(111) is not feasible due to the high activation barriers for some of the elementary steps. Instead, we find that CO2 hydrogenation to hydrocarboxyl (trans-COOH) is kinetically more favorable than formate in the presence of H2O via a unique proton transfer mechanism. The trans-COOH is then converted into hydroxymethylidyne (COH) via dihydroxycarbene (COHOH) intermediates, followed by three consecutive hydrogenation steps to form hydroxymethylene (HCOH), hydroxymethyl (H2COH), and methanol. This is consistent with recent experimental observations [1], which indicate that direct hydrogenation of formate will not produce methanol under dry hydrogen conditions. Thus, both experiment and computational modeling clearly demonstrate the important role of trace amounts of water in methanol synthesis from CO2 hydrogenation on Cu catalysts. The proposed methanol synthesis route on Cu(111) not only provides new insights into methanol synthesis chemistry, but also demonstrates again that spectroscopically observed surface species are often not critical reaction intermediates but rather spectator species. Pacific Northwest National Laboratory is operated by Battelle for the US Department of Energy.

  16. 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......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....

  17. 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

  18. Nanoparticle synthesis in pulsed low temperature discharges

    Energy Technology Data Exchange (ETDEWEB)

    Buss, R.J.

    1996-06-01

    Silicon nitride powders with an average size as low as 7 nm are synthesized in a pulsed radio frequency glow discharge. The as-synthesized silicon nitride powder from a silane/ammonia plasma has a high hydrogen content and is sensitive to oxidation in air. Post-plasma heating of the powder in a vacuum results in nitrogen loss, giving silicon-rich powder. In contrast, heat treatment at 800 C for 20 minutes in an ammonia atmosphere (200 Torr pressure) yields a hydrogen-free powder which is stable with respect to atmospheric oxidation. Several approaches to synthesizing silicon carbide nano-size powders are presented. Experiments using silane/hydrocarbon plasmas produce particles with a high hydrogen content as demonstrated by Fourier transform infrared analysis. The hydrogen is present as both CH and SiH functionality. These powders are extremely air-sensitive. A second approach uses a gas mixture of methyltrichlorosilane and hydrogen. The particles have a low hydrogen content and resist oxidation. Particle morphology of the silicon carbide is more spherical and there is less agglomeration than is observed in the silicon nitride powder.

  19. Low Temperature Synthesis of Semiconductor Materials

    Science.gov (United States)

    1993-09-14

    Kapfer and P.Boudjouk, J. Organomnetal. Chem., 1.4. (1978) C6. 18. "The Photolysis of 1, .1-Dimethylsilacyclobutane", R. D. Koob, P. Boudiouk, and S...Determined by Gas Phase Electron Diffraction’, 0. Shen, C. A. Kapfer , P. Boudjouk, and R. L Hilderbrandt, J. Organometal. Chem., 1§2, (1979) 147. 22. "The...23. "The Structure of 1-Methyl-i -Germaadamantane as Determined by Gas Phase Electron Diffraction", 0. Shen, C. A. Kapfer , P. Boudjouk, and R. L

  20. Direct and Highly Selective Conversion of Synthesis Gas into Lower Olefins: Design of a Bifunctional Catalyst Combining Methanol Synthesis and Carbon-Carbon Coupling.

    Science.gov (United States)

    Cheng, Kang; Gu, Bang; Liu, Xiaoliang; Kang, Jincan; Zhang, Qinghong; Wang, Ye

    2016-04-01

    The direct synthesis of lower (C2 to C4) olefins, key building-block chemicals, from syngas (H2/CO), which can be derived from various nonpetroleum carbon resources, is highly attractive, but the selectivity for lower olefins is low because of the limitation of the Anderson-Schulz-Flory distribution. We report that the coupling of methanol-synthesis and methanol-to-olefins reactions with a bifunctional catalyst can realize the direct conversion of syngas to lower olefins with exceptionally high selectivity. We demonstrate that the choice of two active components and the integration manner of the components are crucial to lower olefin selectivity. The combination of a Zr-Zn binary oxide, which alone shows higher selectivity for methanol and dimethyl ether even at 673 K, and SAPO-34 with decreased acidity offers around 70% selectivity for C2-C4 olefins at about 10% CO conversion. The micro- to nanoscale proximity of the components favors the lower olefin selectivity.

  1. Low-temperature synthesis of SmFeAsO{sub 0.7}F{sub 0.3-{delta}} wires with a high transport critical current density

    Energy Technology Data Exchange (ETDEWEB)

    Wang Lei; Qi Yanpeng; Wang Dongliang; Gao Zhaoshun; Zhang Xianping; Zhang Zhiyu; Wang Chunlei; Ma Yanwei, E-mail: ywma@mail.iee.ac.c [Key Laboratory of Applied Superconductivity, Institute of Electrical Engineering, Chinese Academy of Sciences, PO Box 2703, Beijing 100190 (China)

    2010-07-15

    Ag-sheathed SmFeAsO{sub 0.7}F{sub 0.3-{delta}} (Sm-1111) superconducting wires were prepared by a one-step solid state reaction at temperatures as low as 850-900 {sup 0}C, instead of commonly used temperatures of 1150-1250 {sup 0}C. The x-ray diffraction pattern of the as-sintered samples is well indexed on the basis of the tetragonal ZrCuSiAs-type structure. We characterized the transport critical current density J{sub c} of the SmFeAsO{sub 0.7}F{sub 0.3-{delta}} wires in increasing and subsequently decreasing fields, by a resistive four-probe method. A transport J{sub c} as high as {approx} 1300 A cm{sup -2} at 4.2 K and self-field has been observed for the first time in Sm-1111 type polycrystalline superconductors. The J{sub c} also shows a rapid depression in small applied fields as well as a magnetic-history dependence, indicating weak-linked grain boundaries. The low-temperature synthesis method can be very beneficial for fabricating the RE-1111 iron oxypnictides in a convenient and safe way.

  2. Preparation of in situ secondary synthesis of indoor air purification functional fabric at low temperature%低温原位二次合成法制备室内空气净化功能织物

    Institute of Scientific and Technical Information of China (English)

    王振华; 刘保江; 何瑾馨

    2011-01-01

    Air purification functional fabric with practical value was prepared using in situ secondary synthesis method at low temperature.The surface morphology of air purification functional fabric was characterized by scanning electron microscope (SEM), energy dispersive spectrometer (EDS), atomic force microscopy (AFM) and X-ray diffraction (XRD).The good air purification ability of the treated fabric was confirmed by the degradation test of formaldehyde.In addition, the strength of TiO2 secondary synthesized cotton fabric distinctly increased,and the fabric showed excellent UV irradiation protection properties.%以低温原位二次合成法,制备了具有实用价值的空气净化功能织物.利用扫描电镜(SEM)、能谱分析(EDS)、原子力显微镜(AFM)和X射线衍射(XRD)表征空气净化功能织物表面的形态结构,并通过甲醛降解试验证明了其具有较好的空气净化能力.此外,棉织物经TiO2低温原位二次合成后强73增加明显,且具备极佳的紫外线防护特性.

  3. Synthesis of Pt and Pt-Fe nanoparticles supported on MWCNTs used as electrocatalysts in the methanol oxidation reaction

    Institute of Scientific and Technical Information of China (English)

    J.R.Rodriguez; R.M.F´elix; E.A.Reynoso; Y.Gochi-Ponce; Y.Verde Gómez; S.Fuentes Moyado; G.Alonso-N ´uñez

    2014-01-01

    This work reports a feasible synthesis of highly-dispersed Pt and Pt-Fe nanoparticles supported on multiwall carbon nanotubes (MWCNTs) without Fe and multiwall carbon nanotubes with iron (MWCNTs-Fe) which applied as electrocatalysts for methanol electrooxidation. A Pt coordination complex salt was synthesized in an aqueous solution and it was used as precursor to prepare Pt/MWCNTs, Pt/MWCNTs-Fe, and Pt-Fe/MWCNTs using FeCl2·4H2O as iron source which were named S1, S2 and S3, respectively. The coordination complex of platinum (TOA)2PtCl6 was obtained by the chemical reaction between (NH4)2PtCl6 with tetraoctylammonium bromide (TOAB) and it was characterized by FT-IR and TGA. The materials were characterized by Raman spectroscopy, SEM, EDS, XRD, TEM and TGA. The electrocatalytic activity of Pt-based supported on MWCNTs in the methanol oxidation was investigated by cyclic voltammetry (CV) and chronoamperometry (CA). Pt-Fe/MWCNTs electrocatalysts showed the highest electrocatalytic activity and stability among the tested electrocatalysts due to that the addition of”Fe”promotes the OH species adsorption on the electrocatalyst surface at low potentials, thus, enhancing the activity toward the methanol oxidation reaction (MOR).

  4. 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.

  5. Influence of Aging Time on the Properties of Precursors of CuO/ZnO Catalysts for Methanol Synthesis

    Institute of Scientific and Technical Information of China (English)

    Deren Fang; Zhongmin Liu; Shuanghe Meng; Ligang Wang; Lei Xu; Hua Wang

    2005-01-01

    The aging process of pure copper precursors and copper-zinc binary precursors were studied by XRD, TG-DTG and TPR techniques. The catalytic activity and stability of CuO/ZnO were tested using fixed-bed flow reactor, and the physical properties of the catalysts and Cu species were characterized with N2 adsorption and N2O passivation method, respectively. For the Cu-Zn binary system prepared at the precipitating condition of pH=8.0 and temperature=80 ℃, the initial phase was a mixture of copper nitrate hydroxide Cu2(NO3)(OH)3, georgeite and hydrozincite Zn5(CO3)2(OH)6. By increasing the duration of its aging time, the phase of Cu2(NO3)(OH)2 first transited to georgeite, and then interdiffused into Zn5(CO3)2(OH)6 and resulted in two new phases: rosasite (Cu,Zn)2CO3(OH)2 and aurichalcite (Zn,Cu)5(CO3)2(OH)6. The former phase was much easier to be formed than the latter one,while the latter phase was more responsible for the activity of methanol synthesis than the former one. It is found that the composition and structure of the precursors altered obviously after the colour transition point. The experimental results showed that methanol synthesis is a structure-sensitive catalytic reaction.

  6. 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.

  7. 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 foun

  8. 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...... on particle size, which suggests that the reaction is structure sensitive....

  9. 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 foun

  10. 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

  11. Copper(II) mediated facile and ultra fast peptide synthesis in methanol.

    Science.gov (United States)

    Mali, Sachitanand M; Jadhav, Sandip V; Gopi, Hosahudya N

    2012-07-18

    A novel, ultrafast, mild and scalable amide bond formation strategy in methanol using simple thioacids and amines is described. The mechanism suggests that the coupling reactions are initially mediated by CuSO(4)·5H(2)O and subsequently catalyzed by in situ generated copper sulfide. The pure peptides were isolated in satisfactory yields in less than 5 minutes.

  12. Methanol Synthesis from CO2 Hydrogenation with a Cu/Zn/Al/Zr Fibrous Catalyst%Cu/Zn/Al/Zr纳米纤维催化剂上的CO2加氢合成甲醇过程

    Institute of Scientific and Technical Information of China (English)

    安欣; 左宜赞; 张强; 王金福

    2009-01-01

    A highly active Cu/Zn/Al/Zr fibrous catalyst was developed for methanol synthesis from CO2 hydrogenation. Various factors that affect the activity of the catalyst, including the reaction temperature, pressure and space velocity, were investigated. The kinetic parameters in Graaf's kinetic model for methanol synthesis were obtained. A quasi-stable economical process for CO2 hydrogenation through CO circulation was simulated and higher methanol yield was obtained.

  13. Effects of Exogenous Betaine on the Endogenous BetaineSynthesis in Banana under Low Temperature Stress%外源甜菜碱对低温胁迫下香蕉内源甜菜碱合成的影响

    Institute of Scientific and Technical Information of China (English)

    李茂富; 韦建学; 符良峰; 李绍鹏

    2011-01-01

    After being treated with different concentration of BT, then stressed in the artificial bioclimatic chamber under 7℃ low temperature,the effects of exogenous betaine on the endogenous betaine synthesis in leaf and root of banana(Musa AAA Giant Cavendish cv.Brazil) were studied by measuring the content of endogenous betaine and the activities of the betaine key synthetase BADH in the leaves and roots of banana seedlings.The results indicated that after being treated with 10 mg/L BT for 16 h under 7℃,the activity of BADH and the content of endogenous betaine in leaves were increased with highly significant difference.Though the content of endogenous betaine in root was significantly higher than that in control which grows under normal circumstance,the activity of BADH was not significantly increased after being stressed for 24 h.Moreover,the endogenous betaine in leaf has significantly partial correlation with the BADH activity, and significantly correlation with the endogenous betaine in root, but no significantly correlation with the exogenous betaine.These results suggest that exogenous betaine could improve the synthesis and content of endogenous betaine in banana under low temperature stress.Both leaves and root have the ability to synthesize BT.%以巴西香蕉(Musa AAA Giant Cavendish cv.Brazil)幼苗为试验材料,用不同浓度外源甜菜碱(BT)预处理香蕉幼苗后,置于人工气候箱中模拟低温(7℃)胁迫,分别测定香蕉叶片和根系内源甜菜碱的含量和甜菜碱合成关键酶甜菜碱醛脱氢酶(BADH)活性,以探讨外源甜菜碱对香蕉叶片和根系内源甜菜碱合成的影响.结果显示:7℃低温胁迫16 h后,10 mg/L外源甜菜碱即可极显著提高香蕉幼苗叶片BADH活性,叶片内源BT含量也同步极显著增加,低温胁迫24h后根系内源甜菜碱的含量虽显著高于常温对照,其BADH活性却无显著提升.同时,香蕉幼苗叶片内源BT含量的积累与叶片BADH活性的提高具有

  14. Isobutanol-methanol mixtures from synthesis gas. Quarterly technical progress report, 1 April--30 June 30 1996

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1996-07-25

    A series of CuMgCeO{sub x} catalysts have been prepared by coprecipitating the corresponding metal nitrates with a mixed solution of potassium carbonate and potassium hydroxide. Kinetic studies of methanol and ethanol coupling reactions on K-Cu/MgO/CeO{sub 2} and MgO/CeO{sub 2} catalysts indicate that Cu enhances the rates of alcohol dehydrogenation. The cross-coupling reactions of acetaldehyde and {sup 13}C-labeled methanol produce singly-labeled propionaldehyde, suggesting that it forms by the condensation of acetaldehyde and a reactive intermediate derived from methanol. Isobutyraldehyde, a precursor to isobutanol, forms via the condensation of propionaldehyde and a reactive C{sub 1} intermediate resulting from methanol. CO{sub 2}, one of the reaction products, poisons both basic and metal sites on Ce-containing CuMgO{sub x} catalysts, resulting in decreases in the rates of both alcohol dehydrogenation (Cu sites) and chain-growth condensation reactions (basic sites). CO{sub 2} inhibits ethanol dehydrogenation on both low-Cu and high-Cu CuMgCeO{sub x} catalysts; however, CO{sub 2} has no effect on the activity of low-Cu Ce-free Cu-MgO{sub x} catalysts, suggesting that the Cu on CuMgCeO{sub x} catalysts is more likely to be oxidized by CO{sub 2} to Cu{sup +} species that can be subsequently stabilized by CeO{sub 2}. CO{sub 2} effects on high-pressure isobutanol synthesis from CO/H{sub 2} have been studied on low- and high-Cu CuMgCeO{sub x} catalysts at 320{degrees}C and 4.5 MPa. CO{sub 2} addition and removal on low- and high-Cu catalysts show similar directional effects on CO conversion. CO conversion is lower at all space velocities in the presence of CO{sub 2}, and removal Of CO{sub 2} from the feed partially recovers CO conversion. CO{sub 2} decreases methanol and isobutanol productivities on both catalysts. Addition of 1-propanol to CO/H{sub 2} feed increases isobutanol production, suggesting that 1-propanol is a precursor to isobutanol.

  15. 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.

  16. The Low Temperature Microgravity Physics Facility

    Science.gov (United States)

    Pensinger, J. F.; Chui, T.; Croonquist, A.; Larson, M.; Liu, F.

    2002-01-01

    The Low Temperature Microgravity Physics Facility currently in the design phase is a multiple user and multiple flight facility intended to provide a long duration low temperature environment onboard the International Space Station.

  17. 羊毛低温染色增深剂的合成及其应用%Synthesis and application of deep colour agent on wool low-temperature dyeing

    Institute of Scientific and Technical Information of China (English)

    余彤; 王雪燕

    2015-01-01

    With WLS(an original cationic agent ) and gelatin ,an optimum synthesis process for cationic proteic deep colour agent which was used to enhance the exhaustion of wool for Lanasol CE black dyestaff (6% ,owf) was obtained as follows :m(gelatin):m(WLS)=1∶16 ,m(NaOH):m(WLS)=1∶100 ,at 60℃ for 4 hours .The structure and performance of the agent was analyzed .The results indicate that the agent shall have the surface performance of wool modified ,which shall result in increasing dye exhaustion .The agent is proved to be an efficient agent for wool dyeing at low temperature .%以自制阳离子交联剂WLS和明胶蛋白为原料,优化出一种有利于提高高浓度(6% owf)兰纳素CE黑染料上染羊毛纤维的阳离子蛋白类增深剂的合成工艺条件,即干明胶与WLS的质量比为1∶16,氢氧化钠与WLS的质量比为1∶100,反应温度60℃,反应时间4h 。并对该助剂的结构和性能进行分析。结果表明,该助剂能够改变羊毛纤维表面性能,促进染料的吸附上染,实现羊毛纤维的低温深浓染色,是一种性能优良的亲羊毛纤维型染色增深剂。

  18. Study on flow mode of combined converter for methanol synthesis from coal-based syngas

    Institute of Scientific and Technical Information of China (English)

    XIAO Zhen-ping; MA Hong-fang; YING Wei-yong; FANG Ding-ye

    2011-01-01

    The mathematic model of combined converter with two different flow modes of gas-cooled reactor was established.The effects of gas flow mode in gas-cooled reactor on combined converter was investigated with the yield of methanol was 1 400 kt/a. The results show that ifthe flow mode of the cooling pipe gas and the catalytic bed gas change from countercurrent to concurrent, the catalytic bed temperature distribution does not fit the most optimum temperature curve of reversible exothermic reaction and the heat duty of heat changer in whole process increased seriously, which means that there is much more equipment investment and more operating cost. The gas flow mode of gas-cooled reactor affects the methanol yield slightly. Therefore, the countercurrent gas flow mode of gas-cooled reactor is more lucrative in the combined converter process.

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

    DEFF Research Database (Denmark)

    Clausen, Lasse Røngaard

    is lost in the biomass torrefaction process, the total efficiencies based on untreated biomass to DME were 64% for the RC plant and 59% for the OT plant. CO2 emissions could be reduced to 3% (RC) or 10% (OT) of the input carbon in the torrefied biomass, by using CO2 capture and storage together...... with certain plant design changes. Accounting for the torrefaction process, which occurs outside the plant, the emissions became 22% (RC) and 28% (OT) of the carbon in the untreated biomass. The estimated costs of the produced DME were $11.9/GJLHV for the RC plant, and $12.9/GJLHV for the OT plant...... complete conversion of the carbon in the torrefied biomass, to carbon in the produced methanol, was achieved (97% conversion). The methanol yield per unit biomass input was therefore increased from 66% (the large-scale DME plant) to 128% (LHV). The total energy efficiency was however reduced from 71% (the...

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

    OpenAIRE

    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 found that both these properties increase as the polymer is increasingly sulfonated, with abrupt jumps occurring at a concentration of sulfonic acid groups of about 15 mol%. The most extensively sulfon...

  1. Efficiency Assessment of Using Flammable Compounds from Water Treatment and Methanol Production Waste for Plasma Synthesis of Iron-Containing Pigments

    Science.gov (United States)

    Shekhovtsova, Anastasia P.; Karengin, Alexander G.

    2016-08-01

    This article describes the possibility of applying the low-temperature plasma for obtaining iron-containing pigments from water purification and flammable methanol production waste. In this paper were calculated combustion parameters of water-saltorganic compositions (WSOC) with different consists. Authors determined the modes of energy- efficient processing of the previously mentioned waste in an air plasma. Having considered the obtained results there were carried out experiments with flammable dispersed water-saltorganic compositions on laboratory plasma stand. All the experimental results are confirmed by calculations.

  2. Design and synthesis of palladium/graphitic carbon nitride/carbon black hybrids as high-performance catalysts for formic acid and methanol electrooxidation

    Science.gov (United States)

    Qian, Huayu; Huang, Huajie; Wang, Xin

    2015-02-01

    Here we report a facile two-step method to synthesize high-performance palladium/graphitic carbon nitride/carbon black (Pd/g-C3N4/carbon black) hybrids for electrooxidizing formic acid and methanol. The coating of g-C3N4 on carbon black surface is realized by a low-temperature heating treatment, followed by the uniform deposition of palladium nanoparticles (Pd NPs) via a wet chemistry route. Owning to the significant synergistic effects of the individual components, the preferred Pd/g-C3N4/carbon black electrocatalyst exhibits exceptional forward peak current densities as high as 2155 and 1720 mA mg-1Pd for formic acid oxidation in acid media and methanol oxidation in alkaline media, respectively, far outperforming the commercial Pd-C catalyst. The catalyst also shows reliable stability, demonstrating that the newly-designed hybrids have great promise in constructing high-performance portable fuel cell systems.

  3. 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 hydroxy-c

  4. Methanol synthesis on ZnO(000 anti 1): Free energy landscapes, reaction pathways, and mechanistic insights.

    Energy Technology Data Exchange (ETDEWEB)

    Frenzel, Johannes; Kiss, Janos; Marx, Dominik [LS Theoretische Chemie, Ruhr-Universitaet Bochum, 44780 Bochum (Germany); Nair, Nisanth [Dept. of Chemistry, IIT, Kanapur (India); Meyer, Bernd [ICMM, CCC, Universitaet Erlangen-Nuernberg (Germany)

    2011-07-01

    The interplay of physical and chemical processes in the heterogeneous catalytic synthesis of methanol on the ZnO(000 anti 1) surface with oxygen vacancies is expected to give rise to a complex free energy landscape. A manifold of intermediate species and reaction pathways has been proposed over the years for the reduction of CO on this catalyst at high temperature and pressure conditions as required in the industrial process. In the present study, the underlying complex reaction network from CO to methanol is generated in the first place by using ab initio metadynamics for computational heterogeneous catalysis. After having synthesized the previously discussed intermediates in addition to finding novel species, mechanistic insights into this network of surface chemical reactions are obtained based on exploring the global free energy landscape, which is refined by investigating individual reaction pathways. Furthermore, the impact of homolytic adsorption and desorption of hydrogen at the required reducing gas phase conditions are probed by studying such processes using different charge states of the F-center.

  5. Methanol synthesis on ZnO({{000overline{1}}}). II. Structure, energetics, and vibrational signature of reaction intermediates

    Science.gov (United States)

    Kiss, Janos; Frenzel, Johannes; Meyer, Bernd; Marx, Dominik

    2013-07-01

    A rigorous characterization of a wealth of molecular species adsorbed at oxygen defects on ZnO(000overline{1}) is given. These defects represent the putative active sites in methanol synthesis from CO and H2. The oxidation state of the ZnO catalyst and thus the preferred charge state and the reactivity of the oxygen vacancies depend on the gas phase temperature and pressure conditions. Considering charge states of oxygen vacancies relevant at the reducing conditions of the industrial process, i.e., F++/H2, F0, F0/H2, and F-, as well as the F++ center which is abundant at UHV conditions and therefore important to allow for comparison with surface science experiments, we have investigated the structure, energetics, and vibrational frequencies of an exhaustive catalog of reaction intermediates using electronic structure calculations. After having identified the characteristic adsorption modes of CO, formate, formic acid, hydroxymethylene, formyl, formaldehyde, dioxomethylene, hydroxymethyl, hydroxymethoxide, methoxide, as well as methanol itself, the thermodynamic stability of all species with respect to the charge state of the oxygen vacancy and their electronic stabilization is discussed in detail and summarized in an energy level diagram.

  6. Water and methanol in low-mass protostellar outflows: gas-phase synthesis, ice sputtering and destruction

    CERN Document Server

    Suutarinen, Aleksi N; Mottram, Joseph C; Fraser, Helen J; van Dishoeck, Ewine F

    2014-01-01

    Water in outflows from protostars originates either as a result of gas-phase synthesis from atomic oxygen at T > 200 K, or from sputtered ice mantles containing water ice. We aim to quantify the contribution of the two mechanisms that lead to water in outflows, by comparing observations of gas-phase water to methanol (a grain surface product) towards three low-mass protostars in NGC1333. In doing so, we also quantify the amount of methanol destroyed in outflows. To do this, we make use of JCMT and Herschel-HIFI data of H2O, CH3OH and CO emission lines and compare them to RADEX non-LTE excitation simulations. We find up to one order of magnitude decrease in the column density ratio of CH3OH over H2O as the velocity increases in the line wings up to ~15 km/s. An independent decrease in X(CH3OH) with respect to CO of up to one order of magnitude is also found in these objects. We conclude that gas-phase formation of H2O must be active at high velocities (above 10 km/s, relative to the source velocity) to re-form...

  7. Microwave assisted synthesis and characterization of Ni/NiO nanoparticles as electrocatalyst for methanol oxidation in alkaline solution

    Science.gov (United States)

    Arunachalam, Prabhakarn; Ghanem, Mohamed A.; Al-Mayouf, Abdullah M.; Al-shalwi, Matar; Hamed Abd-Elkader, Omar

    2017-02-01

    Nickel/Nickel oxide (Ni/NiO) nanoparticles catalyst is prepared by microwave-assisted liquid-phase deposition using ethylene glycol (EG) and water mixture under atmospheric conditions. The physicochemical characterizations of the catalyst carried out by surface area analyzer, x-ray diffraction (XRD), x-ray photoelectron spectroscopy (XPS), electron microscopes measurements suggest the formation of crystalline nanoparticles structure of NiO. The surface area of Ni/NiO prepared using EG/water mixture reaches 70 m2 g-1 which is 2-fold enhsancement in surface area in comparison with NiO prepared in pure EG and an order of magnitude higher than that of bulk nickel prepared in pure water. The methanol electro-oxidation activity of the Ni/NiO nanoparticles obtained in EG/water mixture displayed more than 4-fold increase in oxidation current at 1.7 V versus RHE in comparison with NiO nanoparticles obtained in EG and 20-fold increase compared to bulk nickel catalyst concord with the enhancement of electro-active surface area. The results show the Ni/NiO nanoparticles produced by microwave assisted synthesis has superior activity for methanol oxidation in alkaline solution over the other nickel based catalysts and has potential for mass production.

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

    Science.gov (United States)

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

    2015-04-01

    Controlled assembly in aqueous solution was used to synthesize the well-organized Pt/CS/PW12-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/PW12-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 H3PW12O40 (PW12) 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/PW12-GNs toward methanol oxidation and better tolerance of CO. The as-synthesized Pt/CS/PW12-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.

  9. Facile synthesis of flower-like platinum nanostructures as an efficient electrocatalyst for methanol electro-oxidation.

    Science.gov (United States)

    Zhang, Jie; Chen, Jinwei; Jiang, Yiwu; Zhou, Feilong; Zhong, Jing; Wang, Gang; Kiani, Maryam; Wang, Ruilin

    2016-10-01

    This paper presents a facile approach for the synthesis of a novel Pt/graphene-nickel foam (Pt/GNF) electrode composed of flower-like Pt nanoparticles (NPs) and 3D graphene. The fabrication process involved the chemical vapor deposition of graphene onto Ni foam as a substrate and the subsequent growth of Pt NPs via a galvanic replacement reaction without using any seed and organic solvent. The surface morphology and composition of the prepared materials were characterized. Meanwhile, cyclic voltammetry and electrochemical impedance spectroscopy were employed to confirm their typical electrochemical characteristics. The as-prepared nanocomposites displayed enhanced catalytic activity and kinetics toward methanol electro-oxidation. Such an excellent performance can be ascribed to the high dispersion of flower-like Pt NPs and to the exposure of more sites provided by the flower-like structure. The improved stability, decreased charge transfer resistance, and enhanced reaction rate of the nanocomposites promise new opportunities for the development of direct methanol fuel cells.

  10. 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.

  11. 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

  12. 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.

  13. Methanol Synthesis over Cu/ZnO/Al2O3: The Active Site in Industrial Catalysis

    Energy Technology Data Exchange (ETDEWEB)

    Behrens, Malte

    2012-03-28

    Unlike homogeneous catalysts, heterogeneous catalysts that have been optimized through decades are typically so complex and hard to characterize that the nature of the catalytically active site is not known. This is one of the main stumbling blocks in developing rational catalyst design strategies in heterogeneous catalysis. We show here how to identify the crucial atomic structure motif for the industrial Cu/ZnO/Al{sub 2}O{sub 3} methanol synthesis catalyst. Using a combination of experimental evidence from bulk-, surface-sensitive and imaging methods collected on real high-performance catalytic systems in combination with DFT calculations. We show that the active site consists of Cu steps peppered with Zn atoms, all stabilized by a series of well defined bulk defects and surface species that need jointly to be present for the system to work.

  14. Fundamental Studies of Methanol Synthesis from CO2 Hydrogenation on Cu(111), Cu Clusters, and Cu/ZnO(000ī)

    Energy Technology Data Exchange (ETDEWEB)

    Liu, P.; Yang, Y.; Evans, J.; Rodriguez, J.A.; White, M.G.

    2010-06-21

    A combination of experimental and theoretical methods were employed to investigate the synthesis of methanolvia CO{sub 2}hydrogenation (CO{sub 2} + 3H{sub 2} {yields} CH{sub 3}OH + H{sub 2}O) on Cu(111) and Cunanoparticle surfaces. High pressure reactivity studies show that Cunanoparticles supported on a ZnO(000{bar 1}) single crystal exhibit a higher catalytic activity than the Cu(111) planar surface. Complementary density functional theory (DFT) calculations of methanol synthesis were also performed for a Cu(111) surface and unsupported Cu{sub 29} nanoparticles, and the results support a higher activity for Cu nanoparticles. The DFT calculations show that methanol synthesis on Cu surfaces proceeds through a formate intermediate and the overall reaction rate is limited by both formate and dioxomethylene hydrogenation. Moreover, the superior activity of the nanoparticle is associated with its fluxionality and the presence of low-coordinated Cu sites, which stabilize the key intermediates, e.g. formate and dioxomethylene, and lower the barrier for the rate-limiting hydrogenation process. The reverse water-gas-shift (RWGS) reaction (CO{sub 2} + H{sub 2} {yields} CO + H{sub 2}O) was experimentally observed to compete with methanol synthesis and was also considered in our DFT calculations. In agreement with experiment, the rate of the RWGS reaction on Cu nanoparticles is estimated to be 2 orders of magnitude faster than methanol synthesis at T = 573 K. The experiments and calculations also indicate that CO produced by the fast RWGS reaction does not undergo subsequent hydrogenation to methanol, but instead simply accumulates as a product. Methanol production from CO hydrogenation via the RWGS pathway is hindered by the first hydrogenation of CO to formyl, which is not stable and prefers to dissociate into CO and H atoms on Cu. Our calculated results suggest that the methanol yield over Cu-based catalysts could be improved by adding dopants or promoters which are able

  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. Controllable galvanic synthesis of triangular Ag-Pd alloy nanoframes for efficient electrocatalytic methanol oxidation.

    Science.gov (United States)

    Xu, Lin; Luo, Zhimin; Fan, Zhanxi; Yu, Sijia; Chen, Junze; Liao, Yusen; Xue, Can

    2015-06-08

    Triangular Ag-Pd alloy nanoframes were successfully synthesized through galvanic replacement by using Ag nanoprisms as sacrificial templates. The ridge thickness of the Ag-Pd alloy nanoframes could be readily tuned by adjusting the amount of the Pd source during the reaction. These obtained triangular Ag-Pd alloy nanoframes exhibit superior electrocatalytic activity for the methanol oxidation reaction as compared with the commercial Pd/C catalyst due to the alloyed Ag-Pd composition as well as the hollow-framed structures. This work would be highly impactful in the rational design of future bimetallic alloy nanostructures with high catalytic activity for fuel cell systems.

  17. A microkinetic model of the methanol oxidation over silver

    DEFF Research Database (Denmark)

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

    2003-01-01

    , 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......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...

  18. 降低甲醇合成膨胀气中的甲醇损失%Reduce the Loss of Methanol in the Methanol Synthesis Gas Expansion

    Institute of Scientific and Technical Information of China (English)

    杨兵

    2016-01-01

    Through analysis indicates expansion slots expandable gas containing methanol vapor with high gaseous methanol are these to flare pipe network,which not only caused a waste of methanol,to make it easier for the torch fluid pipeline corrosion,iMPact on system stability.%通过分析表明膨胀槽中的膨胀气含甲醇蒸汽较高,这些气态甲醇都是去火炬管网,这不但造成了甲醇的浪费,更容易使去火炬的管道腐蚀积液,对系统稳定造成影响。

  19. A NEW ROUTE TO DIRECT CATALYTIC SYNTHESIS OF ACETIC ACID FROM METHANE BY A LOW-TEMPERATURE REACTION%甲烷低温催化直接合成乙酸的新途径

    Institute of Scientific and Technical Information of China (English)

    丁一慧; 黄伟; 晋萍; 谢克昌

    2001-01-01

    The selective conversion of methane to more useful target products such as acetic acid would be far more attractive. The classical utilization and recent research for methane conversion to acetic acid by both the indirect route involved multi-step process through syngas stage and the direct one avoided syngas production were reviewed in this paper. Technology comparison and results analysis of the indirect route with the direct one, and of homogeneous catalyst systems with heterogeneous ones employed in oxidative carbonylation or carboxylation of methane to synthesize acetic acid directly led to such a suggestion as follows. That is, an environmentally benign route to direct synthesis of acetic acid from inexpensive feedstocks methane and carbon dioxide, in particular, using solid, heterogeneous catalysts at low temperature has its remarkable significance in view of energy, environment and economy. The further research will enrich the theory and practice of green C1 chemistry and performance of thermodynamically unfavo-rable reactions.%对甲烷经合成气路线间接制乙酸的现状及在温和条件下直接转化制乙酸的研究进展作了述评.通过对间接与直接路线的比较,以及在直接路线中,甲烷低温氧化羰化和直接羧化制乙酸均相与非均相催化体系的分析,指出了CH4-CO2低温直接合成乙酸在工艺过程上的显著优势,尤其是采用非均相催化体系.该工艺为乙酸合成和CH4与CO2的绿色化学利用开辟了新途径,其研究将会丰富C1化学化工的理论与实践,并为实现热力学不利反应提供实验方法和理论依据.

  20. 低温水相一步合成钛酸钡:颗粒合成研究%Low Temperature One Step Synthesis of Barium Titanate: Particle Formation Mechanism and Large-scale Synthesis

    Institute of Scientific and Technical Information of China (English)

    沈志刚; 张维维; 陈建峰; 甄崇礼

    2006-01-01

    The formation of BaTiO3 nanoparticles via the reaction of BaCl2, TiCl4 and NaOH in aqueous solution has been systematically studied. The formation of BaTiO3 from the ionic precursors has been elucidated to be a very rapid process, occurring at temperature higher than 60℃. Furthermore, the particle size could be controlled by the proper selection of the synthesis conditions (e.g. reactant concentration of 0.5-1.0mol-L-1, temperature of 80-95℃ and pH≥ 13). A two-step precipitation mechanism was proposed. The first stage of the synthesis involved the formation of amorphous Ti-rich gel phase. The second stage of the synthesis was the reaction between the amorphous phase and the solution-based Ba2+ ions, which led to the crystallization of BaTiO3. Based on the particle formation mechanism, a novel method, high gravity reactive precipitation, was proposed and used to mass production of BaTiO3 of average particle size of about 60 nm and with narrow particle size distribution. Because it could break up the amorphous Ti-rich gel into small pieces, intensify mass transfer, promote the reaction rate of amorphous Ti-rich gel with Ba2+ ions.

  1. Activity of Catalyst for Liquid Phase Methanol Synthesis%液相合成甲醇催化剂活性的研究

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    The effects of reduction procedure, reaction temperature and composition of feed gas on the activity of a CuO-ZnO-Al2O3 catalyst for liquid phase methanol synthesis were studied. An optimized procedure different from conventional ones was developed to obtain higher activity and better stability of the catalyst. Both CO and CO2 in the feed gas were found to be necessary to maintain the activity of catalyst in the synthesis process.Reaction temperature was limited up to 523 K, otherwise the catalyst will be deactivated rapidly. Experimental results show that the catalyst deactivation is caused by sintering and fouling, and the effects of CO and CO2 on the catalyst activity are also investigated. The experimental results indicate that the formation of water in the methanol synthesis is negligible when the feed gas contains both CO and CO2. The mechanism for liquid-phase methanol synthesis was discussed and it differed slightly from that for gas-phase synthesis.

  2. 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.

  3. Matter and Methods at Low Temperatures

    CERN Document Server

    Pobell, F

    2007-01-01

    Matter and Methods at Low Temperatures contains a wealth of information essential for successful experiments at low temperatures, which makes it suitable as a reference and textbook. The first chapters describe the low-temperature properties of liquid and solid matter, including liquid helium. The major part of the book is devoted to refrigeration techniques and the physics on which they rely, the definition of temperature, thermometry, and a variety of design and construction techniques. The lively style and practical basis of this text make it easy to read and particularly useful to anyone beginning research in low-temperature physics. Low-temperature scientists will find it of great value due to its extensive compilation of materials data and relevant new results on refrigeration, thermometry, and materials properties. Problems are included as well. Furthermore, this third edition also describes newly developed low-temperature experimentation techniques and new materials properties; it also contains many a...

  4. 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...... is examined by X-ray powder diffraction, determination of the specific surface area by the BET-method, determination of the copper dispersion in the reduced catalyst by a novel N2O-method, by transmission electron microscopy, and by test of the catalytic properties in a catalytic micro-reactor. A low peak...... 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...

  5. Direct synthesis of dimethyl carbonate from CO2 and methanol over CeO2 catalysts of different morphologies

    Indian Academy of Sciences (India)

    UNNIKRISHNAN P; SRINIVAS DARBHA

    2016-06-01

    The direct synthesis of dimethyl carbonate (DMC) from carbon dioxide CO2 and methanol is an attractive approach towards conversion of the greenhouse gas - CO2 into value-added chemicals and fuels.Ceria CeO2 catalyzes this reaction. But the conversion efficiency of CeO2 is enhanced when the byproductwater in the reaction medium is separated by employing trapping agents like 2-cyanopyridine (2-CP). In thiswork, the influence of morphology of CeO2 on the direct synthesis of DMC in presence of 2-CP is reported.CeO2 catalysts of cube, rod, spindle and irregular morphology (Ce - C, Ce - R, Ce - S and Ce - N, respectively)were prepared, characterized and studied as catalysts in the said reaction conducted in a batch mode. Amongall, Ce - S shows superior catalytic performance with nearly 100 mol% of DMC selectivity. Catalytic activitycorrelates with the concentration of acid and base sites of medium strength as well as defect sites. Ce - S has anoptimum number of these active sites and thereby shows superior catalytic performance.

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

    Science.gov (United States)

    Shelepova, Ekaterina V.; Vedyagin, Aleksey A.; Ilina, Ludmila Yu.; Nizovskii, Alexander I.; Tsyrulnikov, Pavel G.

    2017-07-01

    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.

  7. Formation, Activity and Growth of Copper Nanoparticles in Methanol Synthesis Catalysts

    NARCIS (Netherlands)

    van den Berg, R.

    2016-01-01

    Supported metal catalysts play a pivotal role in the production of fuels and chemicals, in the purification of exhaust gases and in electrochemical energy conversion systems. Further improvement of these materials requires a fundamental understanding of the processes involved in the synthesis, the s

  8. Formation, Activity and Growth of Copper Nanoparticles in Methanol Synthesis Catalysts

    NARCIS (Netherlands)

    van den Berg, R.|info:eu-repo/dai/nl/358212049

    2016-01-01

    Supported metal catalysts play a pivotal role in the production of fuels and chemicals, in the purification of exhaust gases and in electrochemical energy conversion systems. Further improvement of these materials requires a fundamental understanding of the processes involved in the synthesis, the s

  9. A Novel Non-phosgene Process for the Synthesis of Methyl N-Phenyl Carbamate from Methanol and Phenylurea:Effect of Solvent and Catalyst

    Institute of Scientific and Technical Information of China (English)

    WANG,Xin-Kui(王心葵); YAN,Shi-Run(闫世润); CAO,Yong(曹勇); FAN,Kang-Nian(范康年); HE,He-Yong(贺鹤勇); KANG,Mao-Qing(亢茂青); PENG,Shao-Yi(彭少逸)

    2004-01-01

    A novel environmentally benign process for the synthesis of methyl N-phenyl carbamate (MPC) from methanol and phenylurea was studied. Effect of solvent and catalyst on the reaction behavior was investigated. The IR spectra of methanol and phenylurea dissolved in different solvents were also recorded. Compared with use of methanol as both a reactant and a solvent, phenylurea conversion and selectivity to MPC increased by using toluene, benzene or anisole as a solvent, while phenylurea conversion decreased slightly by using n-octane as a solvent. The phenylurea conversion declined nearly 50% when dimethyl sulfoxide (DMSO) was used as a reaction media, and MPC selectivity decreased as well. The catalytic reaction tests showed that a basic catalyst enhanced the selectivity to MPC while an acidic catalyst promoted the formation of methyl carbamate and aniline. Moderate degree of basicity showed the best catalytic performance in the cases studied.

  10. 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.

  11. Low Temperature Induced Conformation Changes of Aminoacylase

    Institute of Scientific and Technical Information of China (English)

    谢强; 孟凡国; 周海梦

    2004-01-01

    Control of aggregation, by lowering temperature and protein concentrations, can enhance the extent of successful refolding. The low temperature has been used in protein folding studies, as undesired aggregations often occur at higher temperatures. Therefore, it is very important to study the effects of low temperature on the native enzyme to help understand the factors that affect the structure of the proteins. In this paper, aminoacylase was studied at different temperatures by measuring enzyme activity, fluorescence emission spectra, and ultraviolet difference spectra. The results show that aminoacylase conformation changes as the temperature changes, becoming more compact at low temperatures, and having more secondary structural content. However, the activity is very low at low temperature, and totally diminishes at 4℃. Aminoacylase tends therefore to be more condense, with less residues exposed and low enzyme activities at low temperature. This observation might explain the self-protection of organisms under conditions of extreme temperature.

  12. 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.

  13. 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

    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......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...... 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...

  14. Causes Analysis and Countermeasures of Methanol Synthesis Paraffinning%甲醇合成结蜡的原因及对策

    Institute of Scientific and Technical Information of China (English)

    宋志远

    2015-01-01

    在甲醇合成催化剂使用后期,常有高烷烃混合物及石蜡生成,结蜡严重时会引起甲醇分离器堵塞,甚至会导致被迫停车清蜡。针对这一问题,介绍了石蜡的性质、产生条件和除蜡的方法,阐述了石蜡产生的主要原因,并从催化剂的选择、合成塔的选用、甲醇合成条件的控制、工艺操作的控制等方面论述了所采取的措施,对甲醇的生产操作实践具有指导意义。%In late stage of methanol synthesis catalyst, it always generates high paraffin mixture and paraffin. It can lead to methanol separator blockage, even shut-down for paraffin removal. Regarding this question, this paper introduces the nature, generation conditions and reasons of paraffin and ways of paraffin removal. At the same time, it also puts forward measures in terms of selection of catalyst and synthetic column, control of methanol synthesis con-dition and process operation, which provides some guidances for methanol production.

  15. Methanol synthesis via CO₂ hydrogenation over a Au/ZnO catalyst: an isotope labelling study on the role of CO in the reaction process.

    Science.gov (United States)

    Hartadi, Yeusy; Widmann, Daniel; Behm, R Jürgen

    2016-04-28

    Methanol synthesis for chemical energy storage, via hydrogenation of CO2 with H2 produced by renewable energies, is usually accompanied by the undesired formation of CO via the reverse water-gas shift reaction. Aiming at a better mechanistic understanding of methanol formation from CO2/H2 on highly selective supported Au/ZnO catalysts we have investigated the role of CO in the reaction process using isotope labelling experiments. Using (13)C-labelled CO2, we found for reaction at 5 bar and 240 °C that (i) the methanol formation rate is significantly higher in CO2-containing gas mixtures than in a CO2-free mixture and (ii) in mixtures containing both CO2 and CO methanol formation from CO increases with the CO content up to 1% CO, and then remains at 20% of the total methanol formation up to a CO2/CO ratio of 1/1, making CO2 the preferred carbon source in these mixtures. A shift in the preferred carbon source for MeOH from CO2 towards CO is observed with increasing reaction temperatures between 240 °C and 300 °C. At even higher temperatures CO is expected to become the dominant carbon source. The consequences of these findings for the application of Au/ZnO catalysts for chemical storage of renewable energies are discussed.

  16. Bridging the Time Gap: A Copper/Zinc Oxide/Aluminum Oxide Catalyst for Methanol Synthesis Studied under Industrially Relevant Conditions and Time Scales.

    Science.gov (United States)

    Lunkenbein, Thomas; Girgsdies, Frank; Kandemir, Timur; Thomas, Nygil; Behrens, Malte; Schlögl, Robert; Frei, Elias

    2016-10-01

    Long-term stability of catalysts is an important factor in the chemical industry. This factor is often underestimated in academic testing methods, which may lead to a time gap in the field of catalytic research. The deactivation behavior of an industrially relevant Cu/ZnO/Al2 O3 catalyst for the synthesis of methanol is reported over a period of 148 days time-on-stream (TOS). The process was investigated by a combination of quasi in situ and ex situ analysis techniques. The results show that ZnO is the most dynamic species in the catalyst, whereas only slight changes can be observed in the Cu nanoparticles. Thus, the deactivation of this catalyst is driven by the changes in the ZnO moieties. Our findings indicate that methanol synthesis is an interfacially mediated process between Cu and ZnO.

  17. Low-Temperature Power Electronics Program

    Science.gov (United States)

    Patterson, Richard L.; Dickman, John E.; Hammoud, Ahmad; Gerber, Scott

    1997-01-01

    Many space and some terrestrial applications would benefit from the availability of low-temperature electronics. Exploration missions to the outer planets, Earth-orbiting and deep-space probes, and communications satellites are examples of space applications which operate in low-temperature environments. Space probes deployed near Pluto must operate in temperatures as low as -229 C. Figure 1 depicts the average temperature of a space probe warmed by the sun for various locations throughout the solar system. Terrestrial applications where components and systems must operate in low-temperature environments include cryogenic instrumentation, superconducting magnetic energy storage, magnetic levitation transportation system, and arctic exploration. The development of electrical power systems capable of extremely low-temperature operation represents a key element of some advanced space power systems. The Low-Temperature Power Electronics Program at NASA Lewis Research Center focuses on the design, fabrication, and characterization of low-temperature power systems and the development of supporting technologies for low-temperature operations such as dielectric and insulating materials, power components, optoelectronic components, and packaging and integration of devices, components, and systems.

  18. Enantiopure inherently chiral calix[4]arene derivatives containing quinolin-2-yl-methanol moiety:Synthesis and application in the catalytic asymmetric addition of diethylzinc to benzaldehyde

    Institute of Scientific and Technical Information of China (English)

    2009-01-01

    A series of novel N,O-type chiral ligands derived from enantiopure inherently chiral calix[4]arenes containing quinolin-2-yl-methanol moiety in the cone or partialcone conformation have been synthe-sized and characterized. Moreover,they have been applied to the catalytic asymmetric addition of diethylzinc to benzaldehyde,which represents the first example that the inherently chiral calixarene can be used as the chiral ligands for the catalytic asymmetric synthesis.

  19. Easy synthesis approach of Pt-nanoparticles on polyaniline surface: an efficient electro-catalyst for methanol oxidation reaction

    Science.gov (United States)

    Mondal, Sanjoy; Malik, Sudip

    2016-10-01

    A facile room temperature and surfactant free synthesis of platinum nanoparticles (Pt-NPs) on benzene tetra-carboxylic acid doped polyaniline (BDP) tube has been successfully demonstrated by solution dipping method. Preparation of Pt-NPs has been done through a red-ox reaction between BDP tubes and Pt-salt, as BDP itself acts as nontoxic reducing agent as well as template cum stabilizer for Pt-NPs. In BDP@Pt composites, ∼2.5 ± 0.5 nm spherical shaped Pt-NPs as observed from TEM studies are nicely decorated on the surface of BDP. The population or the loading density of Pt-NPs on BDP tube is greatly controlled by changing the w/w ratio of BDP to H2PtCl6. Synthesized BDP@Pt composites are subsequently employed as an efficient electro-catalyst for methanol oxidation reaction (MOR) in acidic medium. Furthermore, the observed catalytic activity is consequently ∼12 times higher than that of commercially available Pt/C catalyst. Depending on the loading density of Pt-NPs on BDP tubes, the efficiency and carbon monoxide (CO) tolerance ability of composites have been explored.

  20. [Low temperature plasma technology for biomass refinery].

    Science.gov (United States)

    Fu, Xiaoguo; Chen, Hongzhang

    2014-05-01

    Biorefinery that utilizes renewable biomass for production of fuels, chemicals and bio-materials has become more and more important in chemical industry. Recently, steam explosion technology, acid and alkali treatment are the main biorefinery treatment technologies. Meanwhile, low temperature plasma technology has attracted extensive attention in biomass refining process due to its unique chemical activity and high energy. We systemically summarize the research progress of low temperature plasma technology for pretreatment, sugar platflow, selective modification, liquefaction and gasification in biomass refinery. Moreover, the mechanism of low temperature plasma in biorefinery and its further development were also discussed.

  1. Industrial low temperature utilization of geothermal resources

    Energy Technology Data Exchange (ETDEWEB)

    Howard, J.H.

    1976-05-01

    This brief presentation on industrial utilization of low temperature geothermal resources first considers an overview of what has been achieved in using geothermal resources in this way and, second, considers potential, future industrial applications.

  2. A New Process for Synthesis of Dimethyl Carbonate from Ethylene Carbonate and Methanol without any Catalyst under Supercritical Conditions

    Institute of Scientific and Technical Information of China (English)

    Xiu Juan FENG; Xiao Gang LI; Ren HE; Hui ZHOU

    2005-01-01

    Dimethyl carbonate was synthesized by transesterification reaction between ethylene carbonate and methanol under supercritical conditions without any catalyst. Experimental results showed that the residence time and the molar ratio of methanol to ethylene carbonate all can affect the conversion of ethylene carbonate. When the molar ratio of methanol to ethylene carbonate was 8:1, 81.2 % conversion can be achieved at 9.0 MPa and 250℃ after 8 h.

  3. 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

  4. Methanol synthesis from CO2 hydrogenation over La-M-Cu-Zn-O (M = Y, Ce, Mg, Zr) catalysts derived from perovskite-type precursors

    Science.gov (United States)

    Zhan, Haijuan; Li, Feng; Gao, Peng; Zhao, Ning; Xiao, Fukui; Wei, Wei; Zhong, Liangshu; Sun, Yuhan

    2014-04-01

    A series of La-M-Cu-Zn-O (M = Y, Ce, Mg, Zr) based perovskite-type catalysts are prepared by sol-gel method and characterized by XRD, BET, TPR, N2O-adsorption, XPS and TPD techniques. The results indicate that all the catalysts exhibit La2CuO4 perovskite structure. The addition of Ce, Mg and Zr lead to smaller particles, lower reduction temperature, higher Cu dispersion, larger amount of hydrogen desorption at low temperature and more amount of basic sites. However, Y has less affects on the physicochemical properties. The catalysts derived from perovskite-type precursors show high selectivity for methanol, which is correlated with the Cuα+ species that exists in the reduced catalysts. More exposed Cu surface area is favorable for high CO2 conversion.

  5. Kinetic, Spectroscopic, and Theoretical Assessment of Associative and Dissociative Methanol Dehydration Routes in Zeolites

    Energy Technology Data Exchange (ETDEWEB)

    Jones, Andrew J.; Iglesia, Enrique

    2014-11-03

    Mechanistic interpretations of rates and in situ IR spectra combined with density functionals that account for van der Waals interactions of intermediates and transition states within confining voids show that associative routes mediate the formation of dimethyl ether from methanol on zeolitic acids at the temperatures and pressures of practical dehydration catalysis. Methoxy-mediated dissociative routes become prevalent at higher temperatures and lower pressures, because they involve smaller transition states with higher enthalpy, but also higher entropy, than those in associative routes. These enthalpy–entropy trade-offs merely reflect the intervening role of temperature in activation free energies and the prevalence of more complex transition states at low temperatures and high pressures. This work provides a foundation for further inquiry into the contributions of H-bonded methanol and methoxy species in homologation and hydrocarbon synthesis reactions from methanol.

  6. Kinetic, spectroscopic, and theoretical assessment of associative and dissociative methanol dehydration routes in zeolites.

    Science.gov (United States)

    Jones, Andrew J; Iglesia, Enrique

    2014-11-01

    Mechanistic interpretations of rates and in situ IR spectra combined with density functionals that account for van der Waals interactions of intermediates and transition states within confining voids show that associative routes mediate the formation of dimethyl ether from methanol on zeolitic acids at the temperatures and pressures of practical dehydration catalysis. Methoxy-mediated dissociative routes become prevalent at higher temperatures and lower pressures, because they involve smaller transition states with higher enthalpy, but also higher entropy, than those in associative routes. These enthalpy-entropy trade-offs merely reflect the intervening role of temperature in activation free energies and the prevalence of more complex transition states at low temperatures and high pressures. This work provides a foundation for further inquiry into the contributions of H-bonded methanol and methoxy species in homologation and hydrocarbon synthesis reactions from methanol.

  7. The Role of the Coprecipitation Sequence of Salt Precursors on the Genesis of Cu-ZnO-Al2O3 Catalysts: Synthesis, Characterization and Activity for Low Temperature Shift Reaction

    Directory of Open Access Journals (Sweden)

    R.T. Figueiredo

    1998-06-01

    Full Text Available Cu-ZnO-Al2O3 catalysts for the low-temperature water-gas shift reaction were prepared using methods of direct and reverse coprecipitation. The catalysts obtained were characterized by DRX, TPR, XPS, N2O chemisorption, Hg-Porosimetry and BET surface area. It was observed that the precipitation sequence of the precursors led to significant differences in values of copper dispersion and consequently in the activity of the catalyst for the water-gas shift reaction.

  8. An analysis of methanol synthesis from CO and CO 2 on Cu and Pd surfaces by the bond-order-conservation-Morse-potential approach

    Science.gov (United States)

    Shustorovich, Evgeny; Bell, Alexis T.

    1991-08-01

    The mechanisms of methanol synthesis from CO and CO 2 on Cu(111) and Pd(111) have been analyzed using the BOC-MP (bond-order-conservation-Morse-potential) approach. The analysis was based on calculations of the heats of chemisorption, Q, for all adsorbed species and the activation barriers, Δ E∗, for all elementary reactions believed to be involved in the synthesis of methanol from CO and CO 2. The relevant experimental values of Q and Δ E∗, although scarce, agree well with the BOC-MP estimates. The formyl and formate routes to methanol were compared. On Cu(111), the activation barrier for hydrogenation of CO s to HCO s is found to be much larger than that for the desorption of CO s, which makes formyl formation non-competitive. By contrast, on Pd(111) the two barriers are calculated to be practically equal, making it very likely that formyl groups are formed. In the presence of OH s groups, formate formation via the reaction CO s + OH s → HCOO s is found to have a low activation barrier, particularly on Cu(111), where the formate route to methanol is preferred. The rate determining step in this case is projected to be the hydrogenolysis of formate groups to form formaldehyde and atomic oxygen. On Cu(111) the formate route also appears to be efficient for the hydrogenation of CO 2 to methanol, since the activation barrier for H s + CO 2,s → HCOO s is calculated to be smaller than that for desorption of CO 2,s. The reverse is true for Pd(111), which makes the formate route to methanol energetically unfavorable in this case. The mechanism of the WGS reaction has also been considered. It appears that the reaction does not proceed via the formate intermediate, and the rate-determining step for this reaction is projected to be the dissociation of water. On Cu(111), the reverse WGS reaction is found to be competitive with methanol formation. The BOC-MP projections are generally consistent with the observed features of hydrogenation of CO and CO 2 on Cu and Pd

  9. Methanol - alternative fuel road traffic

    Energy Technology Data Exchange (ETDEWEB)

    Muendler, H.

    1980-09-01

    This brochure names the fuel properties that are required for road traffic, discusses the replacement of petrol by methanol, discusses the possibilities of manufacturing methanol, draws up a timetable and an organigram for a (M-15) large scale test and compares costs of petrol, methanol, synthesis process petrol and hydrogenation process petrol. Furthermore, the technical requirements of vehicles as well as test results of exhaust gas emissions are also discussed.

  10. Electronics Demonstrated for Low- Temperature Operation

    Science.gov (United States)

    Patterson, Richard L.; Hammond, Ahmad; Gerber, Scott S.

    2000-01-01

    The operation of electronic systems at cryogenic temperatures is anticipated for many NASA spacecraft, such as planetary explorers and deep space probes. For example, an unheated interplanetary probe launched to explore the rings of Saturn would experience an average temperature near Saturn of about 183 C. Electronics capable of low-temperature operation in the harsh deep space environment also would help improve circuit performance, increase system efficiency, and reduce payload development and launch costs. An ongoing research and development program on low-temperature electronics at the NASA Glenn Research Center at Lewis Field is focusing on the design of efficient power systems that can survive and exploit the advantages of low-temperature environments. The targeted systems, which are mission driven, include converters, inverters, controls, digital circuits, and special-purpose circuits. Initial development efforts successfully demonstrated the low-temperature operation and cold-restart of several direct-current/direct-current (dc/dc) converters based on different types of circuit design, some with superconducting inductors. The table lists some of these dc/dc converters with their properties, and the photograph shows a high-voltage, high-power dc/dc converter designed for an ion propulsion system for low-temperature operation. The development efforts of advanced electronic systems and the supporting technologies for low-temperature operation are being carried out in-house and through collaboration with other Government agencies, industry, and academia. The Low Temperature Electronics Program supports missions and development programs at NASA s Jet Propulsion Laboratory and Goddard Space Flight Center. The developed technologies will be transferred to commercial end users for applications such as satellite infrared sensors and medical diagnostic equipment.

  11. Ruby pressure scale in a low-temperature diamond anvil cell

    Science.gov (United States)

    Yamaoka, Hitoshi; Zekko, Yumiko; Jarrige, Ignace; Lin, Jung-Fu; Hiraoka, Nozomu; Ishii, Hirofumi; Tsuei, Ku-Ding; Mizuki, Jun'ichiro

    2012-12-01

    Laser-excited N and R fluorescence lines of heavily doped ruby have been studied up to 26 GPa at low temperatures. While the intensity of the R lines at ambient pressure significantly decreases with decreasing temperature, the intensity of N lines originating from exchange-coupled Cr ion pairs is enhanced at low temperatures. The pressure induced wavelength shift of the N lines at 19 K is well fitted with an empirical formula similar to the equation for the R1 line, showing that the intense N line could be used as an alternative pressure scale at low temperatures. We also observe continuous increase in non-hydrostaticity with increasing pressure at low temperatures when silicone oil and 4:1 mixture of methanol and ethanol are used as pressure media.

  12. Microwave-assisted synthesis of nanosphere-like NiCo2O4 consisting of porous nanosheets and its application in electro-catalytic oxidation of methanol

    Science.gov (United States)

    Gu, Li; Qian, Lei; Lei, Ying; Wang, Yanyan; Li, Jing; Yuan, Hongyan; Xiao, Dan

    2014-09-01

    A fast microwave-assisted synthesis method followed by a post-calcining process is used to prepare three-dimensional (3D) nanosphere-like NiCo2O4 nanostructure. The 3D NiCo2O4 nanospheres are constructed by intertwined two-dimensional (2D) ultrathin mesoporous nanosheets. The nanosphere-like NiCo2O4 has a large specific surface area (SSA, 146.5 m2 g-1) and is successfully applied to electro-catalytic oxidation of methanol. Electrochemical impedance spectroscopy (EIS), cyclic voltammetry (CV) and chronoamperometry (CA) measurements are used to investigate electro-catalytic performance of the as-prepared NiCo2O4. The current density of NiCo2O4/Ni foam (NiCo2O4/NF) electrode in 1 M KOH with 0.5 M methanol is up to 40.9 A g-1. And the current density can be returned to 97% of the original value by replacing new 1 M KOH electrolyte with 0.5 M methanol after a long-term CV cycle (500 cycles). These results show that our prepared NiCo2O4 possesses high electro-catalytic activity and good long-term stability for methanol oxidation. This may be benefit from the unique porous nanosphere-like structure and large SSA.

  13. Facile Synthesis of Core/Shell-like NiCo2O4-Decorated MWCNTs and its Excellent Electrocatalytic Activity for Methanol Oxidation

    Science.gov (United States)

    Ko, Tae-Hoon; Devarayan, Kesavan; Seo, Min-Kang; Kim, Hak-Yong; Kim, Byoung-Suhk

    2016-02-01

    The design and development of an economic and highly active non-precious electrocatalyst for methanol electrooxidation is challenging due to expensiveness of the precursors as well as processes and non-ecofriendliness. In this study, a facile preparation of core-shell-like NiCo2O4 decorated MWCNTs based on a dry synthesis technique was proposed. The synthesized NiCo2O4/MWCNTs were characterized by infrared spectroscopy, scanning electron microscopy, transmission electron microscopy, X-ray diffraction, and selected area energy dispersive spectrum. The bimetal oxide nanoparticles with an average size of 6 ± 2 nm were homogeneously distributed onto the surface of the MWCNTs to form a core-shell-like nanostructure. The NiCo2O4/MWCNTs exhibited excellent electrocatalytic activity for the oxidation of methanol in an alkaline solution. The NiCo2O4/MWCNTs exhibited remarkably higher current density of 327 mA/cm2 and a lower onset potential of 0.128 V in 1.0 M KOH with as high as 5.0 M methanol. The impressive electrocatalytic activity of the NiCo2O4/MWCNTs is promising for development of direct methanol fuel cell based on non-Pt catalysts.

  14. 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.

  15. 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.

    Science.gov (United States)

    Sánchez-De la Torre, Fernando; De la Rosa, Javier Rivera; Kharisov, Boris I; Lucio-Ortiz, Carlos J

    2013-09-30

    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.

  16. Synthesis and Catalytic Performance of Graphene Modified CuO-ZnO-Al2O3 for CO2 Hydrogenation to Methanol

    Directory of Open Access Journals (Sweden)

    Zheng-juan Liu

    2014-01-01

    Full Text Available CuO-ZnO-Al2O3 and graphene nanosheet (GNS were synthesized by coprecipitation route and reduction of exfoliated graphite oxides method, respectively. GNS modified CuO-ZnO-Al2O3 nanocomposites were synthesized by high energy ball milling method. The structure, morphology, and character of the synthesized materials were studied by BET, XRD, TEM, and H2-TPR. It was found that by high energy ball milling method the CuO-ZnO-Al2O3 nanoparticles were uniformly dispersed on GNS surfaces. The catalytic performance for the methanol synthesis from CO2 hydrogenation was also tested. It was shown experimentally that appropriate incorporation of GNS into the CuO-ZnO-Al2O3 could significantly increase the catalyst activity for methanol synthesis. The 10 wt.% GNS modified CuO-ZnO-Al2O3 catalyst gave a methanol space time yield (STY of 92.5% higher than that on the CuO-ZnO-Al2O3 catalyst without GNS. The improved catalytic performance was attributed to the excellent promotion of GNS to dispersion of CuO and ZnO particles.

  17. 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.

  18. QTL analysis of rice low temperature germinability

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    A double haploid population, derived from anther culture of F1 hybrid between a typical indica and a japonica (ZYQ8/JX17), has been used to investigate the low temperature germinability (LTG) at 15C. The low temperature germinability of two parents was significantly different.In 6-11 d, the germination percentage of ZYQ8 was higher than that of JX17. In 12-16 d, the germination percentage of JX17 was higher than that of ZYQ8. The quantitative trait loci (QTLs) of every day for low temperature germinability have been mapped based on a molecular linkage map constructed from this population. In 8-11 d, qLTG-9 was identiffed in C397B-RZ617B on chromosome 9, the additive effect was positive, showing that the allele from JX17 could increase low temperature germinability. In 12-16 d, qLTG4 was mapped between RG908 and CT563 on chromosome 4,the additive effect was negative, showing that the allele from ZYQ8 could increase low temperature germinability. These two QTLs were detected at different stages, showing the complexity of the mechanism of iow temperature germinability.

  19. 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...

  20. Basics of Low-temperature Refrigeration

    CERN Document Server

    Alekseev, A

    2014-01-01

    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.

  1. Low temperature monitoring system for subsurface barriers

    Science.gov (United States)

    Vinegar, Harold J.; McKinzie, II. Billy John

    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.

  2. 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

  3. Microstructural characterization of Cu/ZnO/Al2O3 catalysts for the synthesis and steam reforming of methanol

    OpenAIRE

    2008-01-01

    Cu/ZnO/Al2O3 Katalysatoren stellen ein vielseitig einsetzbares Katalysatorsystem, wie z.B. für die Methanol Synthese sowie für die Methanol Dampfreformierung, dar. Letztere Reaktion kann formal auch als die Rückreaktion der Methanol Synthese ausgehend von CO2 und H2 betrachtet werden. In der vorliegenden Arbeit wurden unterschiedlich präparierte Cu/ZnO/Al2O3 Katalysatoren mittels in situ Röntgenbeugung sowie Röntgenabsorptionsspektroskopie hinsichtlich ihrer Mikrostruktur untersucht. Zusätzli...

  4. 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 bulk...

  5. Design trends in low temperature gas processing

    Energy Technology Data Exchange (ETDEWEB)

    White, W.E.; Battershell, D.D.

    1966-01-01

    The following basic trends reflected in recent design of low-temperature gas processing are discussed: (1) higher recovery levels of light hydrocarbon products; (2) lower process temperatures and lighter absorption oils; (3) increased thermodynamic efficiencies; (4) automation; (5) single rather than multiple units; and (6) prefabrication and preassembly of the operating unit.

  6. Induction methods used in low temperature physics

    NARCIS (Netherlands)

    van de Klundert, L.J.M.; de Rooij, C.; Caspari, M.; van der Marel, L.C.

    1975-01-01

    A study has been made of induction bridges used in low temperature physics. In Part 1 the design of a mutual inductance bridge of the Hartshorn type is discussed. This design is based on a critical analysis of impurity effects of the different parts of the Hartshorn bridge. With this equipment

  7. Industrial Applications of Low Temperature Plasmas

    Energy Technology Data Exchange (ETDEWEB)

    Bardsley, J N

    2001-03-15

    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.

  8. Fuzzy Logic Controller for Low Temperature Application

    Science.gov (United States)

    Hahn, Inseob; Gonzalez, A.; Barmatz, M.

    1996-01-01

    The most common temperature controller used in low temperature experiments is the proportional-integral-derivative (PID) controller due to its simplicity and robustness. However, the performance of temperature regulation using the PID controller depends on initial parameter setup, which often requires operator's expert knowledge on the system. In this paper, we present a computer-assisted temperature controller based on the well known.

  9. The holographic screen at low temperatures

    CERN Document Server

    Kiselev, V V

    2010-01-01

    A permissible spectrum of transverse vibrations for the holographic screen modifies both a distribution of thermal energy over bits at low temperatures and the law of gravitation at small accelerations of free fall in agreement with observations of flat rotation curves in spiral galaxies. This modification relates holographic screen parameters in de Sitter space-time with the Milgrom acceleration in MOND.

  10. Wood preservation of low-temperature carbonisation

    NARCIS (Netherlands)

    Gosselink, R.J.A.; Krosse, A.M.A.; Putten, van der J.C.; Kolk, van der J.C.; Klerk-Engels, de B.; Dam, van J.E.G.

    2004-01-01

    Pine (Pinus sylvestris L.) wood with dimensions (100 x 10 x 10mm) was thermally treated at 275degreesC in a muffle oven to impart resistance to microbial degradation. Low-temperature carbonised pine resulted in a visually homogeneously treated product with a substantial (about 70% w/w) reduced non-c

  11. Synthesis of nanocrystalline γ-Al2O3 by sol-gel and precipitation methods for methanol dehydration to dimethyl ether

    Institute of Scientific and Technical Information of China (English)

    Zahra Hosseini; Majid Taghizadeh; Fereydoon Yaripour

    2011-01-01

    The capability of sol-gel and conventional precipitation techniques for the synthesis of nanocrystalline γ-alumina was investigated.These catalysts were used for vapor-phase dehydration of methanol to dimethyl ether in a fixed-bed reactor under the same operating conditions (T= 300℃,P=1 bar,LHSV = 2.8,11.7,26.1 h-1)and characterized by means of N2 adsorption-desorption,NH3-TPD,XRD,TGA and SEM techniques.According to the experimental results,the catalysts prepared using sol-gel method in non-aqueous medium showed better performance compared with those prepared by other methods.

  12. Facile Synthesis of Core/Shell-like NiCo2O4-Decorated MWCNTs and its Excellent Electrocatalytic Activity for Methanol Oxidation

    OpenAIRE

    Tae-Hoon Ko; Kesavan Devarayan; Min-Kang Seo; Hak-Yong Kim; Byoung-Suhk Kim

    2016-01-01

    The design and development of an economic and highly active non-precious electrocatalyst for methanol electrooxidation is challenging due to expensiveness of the precursors as well as processes and non-ecofriendliness. In this study, a facile preparation of core-shell-like NiCo2O4 decorated MWCNTs based on a dry synthesis technique was proposed. The synthesized NiCo2O4/MWCNTs were characterized by infrared spectroscopy, scanning electron microscopy, transmission electron microscopy, X-ray dif...

  13. 低温剥离法制备高性能石墨烯/ZnO复合材料%Facile Synthesis of Graphene/ZnO Nanocomposites by a Low-temperature Exfoliation Method

    Institute of Scientific and Technical Information of China (English)

    袁文辉; 顾叶剑; 李保庆; 李莉

    2012-01-01

    Graphite oxide/ZnO was prepared at low temperature (80℃) with graphite oxide (GO) and zinc sulfate heptahydrate (ZnSO4·7H2O) as initial reactants. The graphene/ZnO (GNS/ZnO) was then prepared by a low-temperature chemical exfoliation method. The as-prepared GNS/ZnO was characterized by X-ray diffraction (XRD), Fourier transform infrared spectroscope (FT-IR), thermo-gravimetric analysis (TG), X-ray photoelectron spectroscopy (XPS), Raman spectra (RS), scanning electron microscope (SEM) and transmission electron microscope (TEM), respectively. The results indicate that GO is completely reduced to graphene and the well-dispersed ZnO nanoparticles are successfully deposited on graphene sheets as spacers to keep the neighboring sheets separate. Photoluminescence spectra of ZnO and GNS/ZnO nanocomposites display the fluorescence quenching property of GNS/ZnO, implying that the GNS/ZnO nanocomposites are expected for practical use in the field of photoelectron-ics.%采用氧化石墨和七水合硫酸锌作为初始反应物,在低温下(80℃)合成了氧化石墨/ZnO,然后通过低温剥离法制备了高质量石墨烯/ZnO (GNS/ZnO)复合材料,采用X射线衍射(XRD)、傅里叶变换红外(FTIR)光谱、热重分析仪(TG)、X射线光电子能谱(XPS)、拉曼光谱(RS)、扫描电子显微镜(SEM)和透射电子显微镜(TEM)等分析手段对石墨烯/znO样品进行了表征.结果表明:氧化石墨还原彻底,纳米ZnO成功地负载到了石墨烯上,有效地减少了石墨烯片层间的团聚现象.通过对ZnO和石墨烯/ZnO荧光性能测试,结果表明:石墨烯/ZnO发生了荧光淬灭现象,在光电子领域拥有广阔的应用前景.

  14. 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.

  15. 甲醇合成环路弛放气深度利用%Optimal utilization of purge gas from the synthesis loop of methanol plant

    Institute of Scientific and Technical Information of China (English)

    何洋

    2012-01-01

    For the problem that the purge gas from the synthesis loop of methanol plant wasn't utilized in high value, an optimal utilization of the purge gas to double its value was proposed, which was to separate all the components from the purge gas by cryogenic method for more valuable use. The proposed concept is valuable for promotion. Especially for the natural gas-based methanol coproduction plants, it could provide a good way for utilizing the purge gas better and also regulate the methanol output.%针对甲醇装置合成环路弛放气价值普遍未得到充分利用的问题,提出了将甲醇弛放气深冷分离提纯各组分,然后分别加以优化利用的思路,实现价值翻倍.同时,该思路也具有推广价值和借鉴意义.特别是针对以天然气为原料联产甲醇的化工企业来说,既可更好地利用弛放气,还可调节甲醇产量.

  16. 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.

  17. 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.

  18. Mayer and virial series at low temperature

    CERN Document Server

    Jansen, Sabine

    2011-01-01

    We analyze the Mayer pressure-activity and virial pressure-density series for a classical system of particles in continuous configuration space at low temperature. Particles interact via a finite range potential with an attractive tail. We propose physical interpretations of the Mayer and virial series' radius of convergence, valid independently of the question of phase transition: the Mayer radius corresponds to a fast increase from very small to finite density, and the virial radius corresponds to a cross-over from monatomic to polyatomic gas. Our results have consequences for the search of a low density, low temperature solid-gas phase transition, consistent with the Lee-Yang theorem for lattice gases and with the continuum Widom-Rowlinson model.

  19. Low-temperature sterilization and new technologies.

    Science.gov (United States)

    Goveia, Vania Regina; Pinheiro, Silma Maria Cunha; Graziano, Kazuko Uchikawa

    2007-01-01

    The new low-temperature sterilization technologies are presented as an alternative to the use of ethylene oxide. This review was performed in order to identify evidences of the antimicrobial activity, toxicity, adverse events and the applicability of these technologies. The research was carried through the electronic databases MEDLINE and LILACS up to 2005. The authors analyzed 10 articles in this survey. The studies about the efficacy of these sterilization methods constitute experimental and comparative research that showed the influence of the extension and diameter of the lumen, besides the presence of crystal salts. Thus, choosing the correct equipment is essential, as well as the assurance of the cleansing of the devices, which interfere with the effectiveness of the low-temperature sterilization. These technologies present limitations regarding the sterilization of graft bone and affect the materials properties.

  20. Peltier effect for producing low temperatures

    Energy Technology Data Exchange (ETDEWEB)

    Hamerak, K.

    1981-01-01

    In connection with the technically extremely difficult and exacting problems of space travel, years ago in the United States the urgent demand for extremely space-saving and at the same time extremely reliable systems for producing continuously variable low temperatures came up. Neither then nor today the set task could be satisfactorily solved using the usual procedures of low-temperature-technology. Looking for a suitable heat pump the engineers came across a physical phenomenon known for more than 130 years: the Peltier effect. In contrast to conventional thermodynamic heat pumps, cooling or heating can be achieved by means of thermoelectric arrangeemnts based on the Peltier effect and depending on the direction of current. The Peltier cells combine a high reliability of functions with small dimensions since they have no system components in motion.

  1. Low-temperature heat transfer in nanowires

    OpenAIRE

    Glavin, B. A.

    2000-01-01

    The new regime of low-temperature heat transfer in suspended nanowires is predicted. It takes place when (i) only ``acoustic'' phonon modes of the wire are thermally populated and (ii) phonons are subject to the effective elastic scattering. Qualitatively, the main peculiarities of heat transfer originate due to appearance of the flexural modes with high density of states in the wire phonon spectrum. They give rise to the $T^{1/2}$ temperature dependence of the wire thermal conductance. The e...

  2. Low-Temperature Spacecraft: Challenges/Opportunities

    Science.gov (United States)

    Dickman, J. E.; Patterson, R. L.; Overton, E.; Hammoud, A. N.; Gerber, S. S.

    2001-01-01

    Imagine sending a spacecraft into deep space that operates at the ambient temperature of its environment rather than hundreds of degrees Kelvin warmer. The average temperature of a spacecraft warmed only by the sun drops from 279 K near the Earth's orbit to 90 K near the orbit of Saturn, and to 44 K near Pluto's orbit. At present, deep space probes struggle to maintain an operating temperature near 300 K for the onboard electronics. To warm the electronics without consuming vast amounts of electrical energy, radioisotope heater units (RHUs) are used in vast numbers. Unfortunately, since RHU are always 'on', an active thermal management system is required to reject the excess heat. A spacecraft designed to operate at cryogenic temperatures and shielded from the sun by a large communication dish or solar cell array could be less complex, lighter, and cheaper than current deep space probes. Before a complete low-temperature spacecraft becomes a reality, there are several challenges to be met. Reliable cryogenic power electronics is one of the major challenges. The Low-Temperature Power Electronics Research Group at NASA Glenn Research Center (GRC) has demonstrated the ability of some commercial off the shelf power electronic components to operate at temperatures approaching that of liquid nitrogen (77 K). Below 77 K, there exists an opportunity for the development of reliable semiconductor power switching technologies other than bulk silicon CMOS. This paper will report on the results of NASA GRC's Low-Temperature Power Electronics Program and discuss the challenges to (opportunities for) the creation of a low-temperature spacecraft.

  3. 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.

  4. 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.

  5. Thermal expansion of glasses at low temperatures

    Energy Technology Data Exchange (ETDEWEB)

    Lyon, K.G.

    1979-01-01

    The linear thermal expansion coefficient (..cap alpha.. = (par. deltalnL/par. deltaT)/sub p/) was measured at temperatures to 1.2K for two amorphous solids, fused silica and PMMA (polymethylmethacrylate, plexiglas), using a parallel plate capacitor differential dilatometer. The low temperature expansion coefficients for these solids have the same temperature dependences as the specific heats, and show a contribution which is linear in the temperature and which can be associated with the postulate of a broad distribution of two level states. The Grueneisen parameters which are associated with this contribution are comparable for the two solids (Y approx. = -16), and suggest a further indication of common behavior for amorphous solids at low temperature. Large magnitudes for Grueneisen parameters (/..gamma../ > 5) generally are associated with tunneling models. A symmetric double harmonic oscillator tunneling model can be used to understand the sign and magnitude of ..gamma.. for these solids. This model is inconsistent with other thermal and thermodynamic data for fused silica. The existence of similar negative and large magnitude Grueneisen parameters for these two amorphous solids places an additional constraint on theories for the low temperature properties of glasses.

  6. Dynamic Simulation of the Methanol Synthesis Reactor with the Aspen Dynamics Software%基于 Aspen Dynamics 的甲醇合成塔动态模拟

    Institute of Scientific and Technical Information of China (English)

    岳芳华; 刘东斌; 申延明

    2014-01-01

    以某年产300 kt甲醇合成装置为研究对象,利用先进的Aspen Plus工程设计软件对其进行全流程稳态模拟;并在稳态模拟的基础上,应用Aspen Dynamics软件对甲醇合成塔进行动态模拟,从而得到可供参考的最优的工艺控制参数,以指导实际生产操作。%Taking the 300 kt/a methanol synthesis unit as the study object ,make its whole process steady‐state simulation with the advanced Aspen Plus engineering design software . On the basis of steady‐state simulation ,make the dynamic simulation of methanol synthesis reactor with the Aspen Dynamics software to obtain the optimal control parameters for reference ,which could guide the actual production operations .

  7. Direct synthesis of dimethyl carbonate from methanol and carbon dioxide over CeO2(X)-ZnO(1-X) nano-catalysts.

    Science.gov (United States)

    Kang, Ki Hyuk; Joe, Wangrae; Lee, Chang Hoon; Kim, Mieock; Kim, Dong Baek; Jang, Boknam; Song, In Kyu

    2013-12-01

    CeO2(X)-ZnO(1-X) (X = 0, 0.1, 0.3, 0.5, 0.7, 0.9, and 1.0) nano-catalysts were prepared by a co-precipitation method with a variation of CeO2 content (X, mol%), and they were applied to the direct synthesis of dimethyl carbonate from methanol and carbon dioxide. Successful formation of CeO2(X)-ZnO(1-X) nano-catalysts was well confirmed by XRD analysis. The amount of DMC produced over CeO2(X)-ZnO(1-X) catalysts exhibited a volcano-shaped curve with respect to CeO2 content. Acidity and basicity of CeO2(X)-ZnO(1-X) nano-catalysts were measured by NH3-TPD and CO2-TPD experiments, respectively, to elucidate the effect of acidity and basicity on the catalytic performance in the reaction. It was revealed that the catalytic performance of CeO2(X)-ZnO(1-X) nano-catalysts was closely related to the acidity and basicity of the catalysts. Amount of dimethyl carbonate increased with increasing both acidity and basicity of the catalysts. Among the catalysts tested, CeO2(0.7)-ZnO(0.3) with the largest acidity and basicity showed the best catalytic performance in the direct synthesis of dimethyl carbonate from methanol and carbon dioxide.

  8. Microwave-assisted synthesis of high-loading, highly dispersed Pt/carbon aerogel catalyst for direct methanol fuel cell

    Indian Academy of Sciences (India)

    Zhijun Guo; Hong Zhu; Xinwei Zhang; Fanghui Wang; Yubao Guo; Yongsheng Wei

    2011-06-01

    A Pt supported on carbon aerogel catalyst has been synthesized by the microwave-assisted polyol process. The Pt supported on carbon aerogel catalyst was characterized by high resolution transmission electron microscopy and X-ray diffraction. The results show a uniform dispersion of spherical Pt nanoparticles 2.5–3.0 nm in diameter. Cyclic voltammetry and chronoamperometry were used to evaluate the electrocatalytic activity of the Pt/carbon aerogel catalyst for methanol oxidation at room temperature. The Pt/carbon aerogel catalyst shows higher electrochemical catalytic activity and stability for methanol oxidation than a commercial Pt/C catalyst of the same Pt loading.

  9. Application research on commercial methanol synthesis catalysts for CO2 hydrogenation to methanol%工业化甲醇催化剂在CO2加氢制备甲醇过程中的应用研究

    Institute of Scientific and Technical Information of China (English)

    戴成勇; 程智利; 宁春利; 张春雷

    2012-01-01

    系统地将工业化甲醇催化剂应用于CO2加氢制备甲醇反应中,考察5种工业化甲醇催化剂在CO2加氢反应中的反应活性,运用ICP、N2 -物理吸附、XRD和H2 - TPR等手段对催化剂进行表征.结果表明,Cu/Zn/Al催化剂具有较高的CO2加氢反应活性,在温度220℃和压力3 MPa条件下,CO2转化率为22.9%,甲醇选择性为64.8%.催化剂活性与组分含量、晶粒大小、比表面积和孔结构等因素有关,CuO和ZnO组分含量越高,催化活性越好,适度晶粒大小的CuO物种可能是该反应中有效催化活性位前驱体,反应规律与甲酸铜中间体理论基本吻合;高比表面积和规整孔结构均有助于提高催化活性.%The catalysts used in commercial methanol synthesis were studied systematically for the hydro-genation of CO2 to methanol for the first time and their performance was investigated in a fixed-bed reactor. The catalysts were characterized by means of XRD,N2 adsorption-desorption,H2-TPR and ICP. The results indicated that Cu/Zn/Al catalysts exhibited higher activity for CO2 hydrogenation, and CO2 conversion and selectivity to methanol were 22. 9% and 64. 8% respectively under the condition of reaction temperature 220 ℃ and reaction pressure 3. 0 Mpa. The activities of the catalysts were mainly related to their component contents, grain sizes, surface areas and pore structures. The higher the contents of CuO/ZnO were,the higher the catalytic activity was. CuO species with appropriate grain sizes might be the effective precursor with catalytic activity, and their reaction rule was consistent with the theory of the HCOO-Cu intermediates. Furthermore, the higher surface area and neat pore structures could improve the activity of the catalyst.

  10. 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.)

  11. Template-assisted synthesis of III-nitride and metal-oxide nano-heterostructures using low-temperature atomic layer deposition for energy, sensing, and catalysis applications (Presentation Recording)

    Science.gov (United States)

    Biyikli, Necmi; Ozgit-Akgun, Cagla; Eren, Hamit; Haider, Ali; Uyar, Tamer; Kayaci, Fatma; Guler, Mustafa Ozgur; Garifullin, Ruslan; Okyay, Ali K.; Ulusoy, Gamze M.; Goldenberg, Eda

    2015-08-01

    Recent experimental research efforts on developing functional nanostructured III-nitride and metal-oxide materials via low-temperature atomic layer deposition (ALD) will be reviewed. Ultimate conformality, a unique propoerty of ALD process, is utilized to fabricate core-shell and hollow tubular nanostructures on various nano-templates including electrospun nanofibrous polymers, self-assembled peptide nanofibers, metallic nanowires, and multi-wall carbon nanotubes (MWCNTs). III-nitride and metal-oxide coatings were deposited on these nano-templates via thermal and plasma-enhanced ALD processes with thickness values ranging from a few mono-layers to 40 nm. Metal-oxide materials studied include ZnO, TiO2, HfO2, ZrO2, and Al2O3. Standard ALD growth recipes were modified so that precursor molecules have enough time to diffuse and penetrate within the layers/pores of the nano-template material. As a result, uniform and conformal coatings on high-surface area nano-templates were demonstrated. Substrate temperatures were kept below 200C and within the self-limiting ALD window, so that temperature-sensitive template materials preserved their integrity III-nitride coatings were applied to similar nano-templates via plasma-enhanced ALD (PEALD) technique. AlN, GaN, and InN thin-film coating recipes were optimized to achieve self-limiting growth with deposition temperatures as low as 100C. BN growth took place only for >350C, in which precursor decomposition occured and therefore growth proceeded in CVD regime. III-nitride core-shell and hollow tubular single and multi-layered nanostructures were fabricated. The resulting metal-oxide and III-nitride core-shell and hollow nano-tubular structures were used for photocatalysis, dye sensitized solar cell (DSSC), energy storage and chemical sensing applications. Significantly enhanced catalysis, solar efficiency, charge capacity and sensitivity performance are reported. Moreover, core-shell metal-oxide and III-nitride materials

  12. Ag-Cu合金纳米颗粒的低温合成与热学性能%Low temperature synthesis and thermal properties of Ag-Cu alloy nanoparticles

    Institute of Scientific and Technical Information of China (English)

    W.BHAGATHSINGH; A.SAMSONNESARAJ

    2013-01-01

    采用一种简单的低温化学还原方法,在水溶液中利用NaBH4作为还原剂还原醋酸或硫酸铜,制备了Ag-Cu纳米颗粒.反应过程中通入氮气来防止生成的合金被氧化.采用XRD、紫外-可见光谱、颗粒尺寸测试、EDS分析、TG-DTA分析和SEM观察等手段来表征合成的Ag-Cu纳米颗粒.XRD分析表明,所合成的Ag-Cu纳米颗粒的晶粒尺寸为15nm左右.紫外-可见光谱分析证实了纳米颗粒的生成.EDS分析表明,样品中存在Ag和Cu.SEM观察表明,所制备的样品的平均晶粒尺寸为40 nm.TG-DTA研究表明,合金的熔点与颗粒尺寸有关.%Ag-Cu alloy nanoparticles were synthesized by simple low temperature chemical reduction method using metal salts (acetate/sulphates) in aqueous solution with sodium borohydride as reducing agent.The chemical reduction was carried out in the presence of nitrogen gas in order to prevent the oxidation of copper during the reaction process.The alloy nanoparticles were characterized by XRD,UV-Vis,particle size analysis,EDS,TG-DTA and SEM analysis.From the XRD analysis,the crystallite sizes of the prepared samples were calculated using Scherrer formula and the values were found to be in the range of 15 nm.UV-Vis studies conform the formation of alloy nanoparticles.EDS analysis shows the presence of silver and copper in the samples.The SEM observation reveals that the samples consist of grains with average grain size up to 40 nm,and the particle size dependant melting point was studied by TG-DTA.

  13. The synthesis and application of low temperature environment friendly poly-acrylate emulsion%低温环保型聚丙烯酸酯乳液的合成及应用

    Institute of Scientific and Technical Information of China (English)

    刘旭; 习智华

    2013-01-01

    The low temperature environment friendly poly-acrylate emulsion adhesive is prepared by seed emulsion polymerization method. It means that, with butyl acrylic (BA), ethylhexyl acrylate (EHA), styrene (St) as soft or hard monomer, acrylic acid (AA) as functional monomer, potassium persulfate as initiator, HA as crosslinking monomer, poly-acrylate adhesive provided with excellent performance for pigment printing is synthesized. The effects of the hard monomer to soft monomer ratio, dosage of functional monomer, dosage of crosslinking monomer and chain transfer agent on the emulsion performance and pigment printing property are discussed. Finally, the optimum process condition of emulsion polymerization is confirmed as follows:the ratio of hard monomers to soft monomers is 1.218 8/1, the dosage of functional monomer is 1.8%, the dosage of crosslinking monomer is 2.6%, and chain transfer agent is 0.52%, dosage of adhesive is 30%, the curing time is 4 min.%  采用种子乳液聚合法合成低温环保型聚丙烯酸酯乳液粘合剂,即以丙烯酸丁酯(BA)、丙烯酸异辛酯(EHA)、苯乙烯(ST)为软、硬单体,丙烯酸(AA)为功能单体,过硫酸钾为引发剂,HA为交联单体,合成了一种性能优良的聚丙烯酸酯涂料印花粘合剂。讨论了软硬单体配比、功能单体用量、交联单体用量及链转移剂对乳液性能及涂料印花性能的影响。最终确定了乳液聚合最佳工艺条件:软/硬单体比为1.2188/1,功能单体AA用量为1.8%,交联单体HA用量为2.6%,链转移剂硫醇用量为0.52%。合成粘合剂在涂料印花上应用时,粘合剂用量为30%,焙烘时间为4 min。

  14. 金属配合物的合成及其在低温漂白中的应用%Synthesis of metal complex and its application in low temperature bleaching

    Institute of Scientific and Technical Information of China (English)

    秦新波; 宋敏; 尹冲; 吴茜; 钟毅; 张琳萍; 徐红; 毛志平

    2012-01-01

    Binuclear manganese complex [ (Me3TACN)2 Mn2 ((μ-0) ( μ-CH3CO2) 2] [ PF6] 2 ·1H2O(MnAcL) and iron complex[ (Me3TACN)2Fe2(μ-O) (μ-CH3CO2 )2 ] [PF6]2·1H2O(FeAcL) of 1,4,7-trimethy]-1 ,4,7-triazacyclononane containing carboxylic bridge were synthesized and characterized by FT-IR, elemental analysis (EA) and TGA, and their structures were confirmed. Low temperature bleaching of knitted cotton fabrics was performed using MnAcL and FeAcL as the catalyst for H2O2 and effects of temperature, complex concentration, H2O2 mass concentration, and pH on the bleaching results were investigated, and the optimized process conditions were determined as follows; 30% H2O2 10 g/L, complex MnAcL 10μmol/L ( FeAcL 15μmol/L) , penetrating agent 1 g/L, stabilizer DTA 1 g/L, pH =10, bleaching at 70℃ for 60 min. The whiteness index and bursting strength retention of fabrics treated with MnAcL and FeAcL were 82. 3% and 65.7% ,and 95.5% and 96.9% Respectively. The fabric bleached with MnAcL at low temperature exhibited similar whiteness and wettability to the fabric bleached with the conventional high temperature bleaching technique, but showed higher bursting strength retention.%合成了1,4,7-三甲基-1,4,7-三氮杂环壬烷(Me3TACN)的羧酸桥连双核锰配合物[(Me3TACN) 2Mn2(μ-O)(μ-CH3CO2)2][PF6]2·1H2O(MnAcL)和铁配合物[(Me3TACN)2Fe2(μ-O)(μ-CH3 CO2)2][PF6]2·1H2O(FeAcL),采用红外光谱(FT-IR)、元素分析(EA)和热重分析(TGA)证实了其结构;并将这2个配合物作为双氧水的催化剂应用于低温漂白棉针织物中.通过单因素实验,探讨了温度、配合物浓度、双氧水质量浓度及pH值对漂白效果的影响,得优化工艺:30% H2O2质量浓度为10 g/L,配合物MnAcL浓度为10 μmol/L(FeAcL 15 μmol/L),渗透剂和稳定剂DTA的质量浓度均为1 g/L,pH值为10,70℃下漂白60 min.经配合物MnAcL处理后的织物白度达82.3%,顶破强力保留率为95.5%;而经配合物FeAcL处理后的织物白度为65.7

  15. Photochemical Synthesis of Au@Pd Core-Shell Nanoparticles for Methanol Oxidation Reaction: the Promotional Effect of the Au Core

    Directory of Open Access Journals (Sweden)

    Dong Yingnan

    2016-01-01

    Full Text Available A novel method for synthesizing Au@Pd core-shell nanoparticles was proposed based on photochemistry. By irradiating the mixture of Au (III and Pd (II ions using ultraviolet light, the Au@Pd core-shell nanoparticles were prepared. The size of the nanoparticles and the thickness of the Pd shell could be efficiently adjusted by changing the molar ratio of Au (III to Pd (II ion. In this way, nanoparticles with diameter in the range of 5.6~4.6 nm were obtained. The core-shell structure of the synthesized nanoparticles was showed by the characterization using UV-Vis, TEM/HR-TEM and XPS. The paper investigated the electrocatalysis performance of Au@Pd nanoparticles in the methanol catalytic oxidation reaction, as well as the electron donating effect of Au core to Pd shell and the promotion of this effect on the catalytic activity of Pd shell. The experimental results provided reference for the development of non-platinum catalysts of low-temperature fuel cell anode.

  16. 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.

  17. Mechanism of bacterial adaptation to low temperature

    Indian Academy of Sciences (India)

    M K Chattopadhyay

    2006-03-01

    Survival of bacteria at low temperatures provokes scientific interest because of several reasons. Investigations in this area promise insight into one of the mysteries of life science – namely, how the machinery of life operates at extreme environments. Knowledge obtained from these studies is likely to be useful in controlling pathogenic bacteria, which survive and thrive in cold-stored food materials. The outcome of these studies may also help us to explore the possibilities of existence of life in distant frozen planets and their satellites.

  18. Low-temperature heat transfer in nanowires.

    Science.gov (United States)

    Glavin, B A

    2001-05-07

    A new regime of low-temperature heat transfer in suspended nanowires is predicted. It takes place when (i) only "acoustic" phonon modes of the wire are thermally populated and (ii) phonons are subject to the effective elastic scattering. Qualitatively, the main peculiarities of heat transfer originate due to the appearance of the flexural modes with high density of states in the wire phonon spectrum. They give rise to the T(1/2) temperature dependence of the wire thermal conductance. Experimental situations where the new regime is likely to be detected are discussed.

  19. Low temperature waste form process intensification

    Energy Technology Data Exchange (ETDEWEB)

    Fox, K. M. [Savannah River Site (SRS), Aiken, SC (United States). Savannah River National Lab. (SRNL); Cozzi, A. D. [Savannah River Site (SRS), Aiken, SC (United States). Savannah River National Lab. (SRNL); Hansen, E. K. [Savannah River Site (SRS), Aiken, SC (United States). Savannah River National Lab. (SRNL); Hill, K. A. [Savannah River Site (SRS), Aiken, SC (United States). Savannah River National Lab. (SRNL)

    2015-09-30

    This study successfully demonstrated process intensification of low temperature waste form production. Modifications were made to the dry blend composition to enable a 50% increase in waste concentration, thus allowing for a significant reduction in disposal volume and associated costs. Properties measurements showed that the advanced waste form can be produced using existing equipment and processes. Performance of the waste form was equivalent or better than the current baseline, with approximately double the amount of waste incorporation. The results demonstrate the feasibility of significantly accelerating low level waste immobilization missions across the DOE complex and at environmental remediation sites worldwide.

  20. 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.

  1. Low temperature vibrational spectroscopy. I. Hexachlorotellurates

    DEFF Research Database (Denmark)

    Berg, Rolf W.; Poulsen, Finn Willy; Bjerrum, Niels

    1977-01-01

    frequency lattice modes were observed and interpreted in terms of a phase transition near 165 K, similar to transitions in other K2[MX6] salts. The cubic tetramethylammonium hexachlorotellurate salt undergoes a phase transition of supposed first order at a temperature near 110 K, corresponding...... to transitions known in analogous uranium and tin compounds. Possible reasons for the transitions are discussed. In the low temperature phases the nu4 and nu6 bendings of [TeCl6]2− have been identified with bands near ~130 and ~110 cm−1. No evidence seemed to favor any stereochemical distortion due to the lone...

  2. Facile synthesis of a mechanically robust and highly porous NiO film with excellent electrocatalytic activity towards methanol oxidation

    Science.gov (United States)

    Wang, Luoyuan; Zhang, Guoge; Liu, Yan; Li, Wenfang; Lu, Wei; Huang, Haitao

    2016-05-01

    Considerable research is being conducted in searching for effective anode catalysts in alkaline direct methanol fuel cells (DMFCs). Although significant progress has been achieved, it is still challenging to prepare non-Pt catalysts with both excellent activity and good durability. Herein, a highly porous NiO film is developed by a facile and fast anodization approach. The anodic NiO film demonstrates a high surface area, large mesopore volume and small crystallite size, leading to facilitated adsorption of reaction species, easy electrolyte penetration and fast reaction kinetics. Furthermore, as anodic NiO is grown in situ on a metallic substrate with strong adhesion strength and good electrical contact, it can be used directly as an anode catalyst for methanol oxidation without the need to add any binder or conducting agent. Such an additive-free approach greatly expedites the catalyst preparation process. The anodic NiO shows lower methanol oxidation potential, higher oxidation current and better catalytic durability than most of the state-of-the-art Ni-based catalysts reported elsewhere. As anodization is a simple, low cost and easily scaled up method, the work described here provides an exciting direction to speed up the practical application of alkaline DMFCs.Considerable research is being conducted in searching for effective anode catalysts in alkaline direct methanol fuel cells (DMFCs). Although significant progress has been achieved, it is still challenging to prepare non-Pt catalysts with both excellent activity and good durability. Herein, a highly porous NiO film is developed by a facile and fast anodization approach. The anodic NiO film demonstrates a high surface area, large mesopore volume and small crystallite size, leading to facilitated adsorption of reaction species, easy electrolyte penetration and fast reaction kinetics. Furthermore, as anodic NiO is grown in situ on a metallic substrate with strong adhesion strength and good electrical contact

  3. Antimisting kerosene: Low temperature degradation and blending

    Science.gov (United States)

    Yavrouian, A.; Parikh, P.; Sarohia, V.

    1988-01-01

    The inline filtration characteristics of freshly blended and degraded antimisting fuels (AMK) at low temperature are examined. A needle valve degrader was modified to include partial recirculation of degraded fuel and heat addition in the bypass loop. A pressure drop across the needle valve of up to 4,000 psi was used. The pressure drop across a 325 mesh filter screen placed inline with the degrader and directly downstream of the needle valve was measured as a function of time for different values of pressure drop across the needle valve. A volume flux of 1 gpm/sq in was employed based on the frontal area of the screen. It was found that, at ambient temperatures, freshly blended AMK fuel could be degraded using a single pass degradation at 4,000 psi pressure drop across the needle valve to give acceptable filterability performance. At fuel temperatures below -20 C, degradation becomes increasingly difficult and a single pass technique results in unacceptable filtration performance. Recirculation of a fraction of the degraded fuel and heat addition in the bypass loop improved low temperature degradation performance. The problem is addressed of blending the AMK additive with Jet A at various base fuel temperatures.

  4. Low temperature operation and exhaust emission

    Energy Technology Data Exchange (ETDEWEB)

    Laurikko, J.

    1987-01-01

    Ambient temperature has the greatest effect on the exhaust emissions of internal combustion engines during the initial cold star and before the engine is fully warmed-up. Fuel evaporation is poor in a cold engine and the fuel-air mixture must be made richer to ensure that the engine weill start and be driveable. However, the combustion of a rich fuel-air mixture is incomplete because of the lack of oxygen, and the exhaust gases will contain an excessive amount of carbon monoxide (CO). The formation of nitrogen oxides (NO/sub x/) in a combustion engine is tied to high temperatures and oxygen concentrations. The conditions in a non-warmed engine using a rich fuel-air mixture are unfavourable for the formation of NO/sub x/ and the emission of NO/sub x/ may even diminish with falling ambient temperature. When the engine has reached its normal operating temperature the exhaust emissions are usually independent of the ambient temperature if the engine is equipped with intake air preheating that is sufficiently powerful. The reduction efficiency of a catalytic converter mainly depends on its operation temperature. Continuous operation at low temperatures may cause rapid poisoning of the converter. At low temperatures, carbon and other particles that do not burn collect on the active surface of the converter reducing its effectiveness.

  5. Low Temperature Spin Structure of Gadolinium Titanate

    Science.gov (United States)

    Javanparast, Behnam; McClarty, Paul; Gingras, Michel

    2012-02-01

    Many rare earth pyrochlore oxides exhibit exotic spin configurations at low temperatures due to frustration. The nearest neighbor coupling between spins on the corner-sharing tetrahedral network generate geometrical magnetic frustration. Among these materials, gadolinium titanate (Gd2Ti2O7) is of particular interest. Its low temperature ordered phases are not yet understood theoretically. Bulk thermal measurements such as specific heat and magnetic susceptibility measurements find two phase transitions in zero external field, in agreement with simple mean field calculations. However, recent neutron scattering experiments suggest a so-called 4-k spin structure for intermediate phase and a so called canted 4-k structure for lower temperature phase that does not agree with either mean-field theory or Monte Carlo simulation which find the 1-k state and Palmer-Chalker state respectively as the lowest free energy configuration for those phases. In our work, we study the 4-k structure in detail and present a new phase diagram for dipolar Heisenberg spins on a pyrochlore lattice, certain portions of which describe gadolinium titanate.

  6. 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.

  7. Low-temperature ashing of Bulgarian lignites

    Energy Technology Data Exchange (ETDEWEB)

    Douchanov, D.; Minkova, V.; Martinez-Alonso, A.; Palacios, J.M.; Tascon, J.M.D. [Bulgarian Academy of Sciences, Sofia (Bulgaria). Inst. of Organic Chemistry

    1993-12-01

    The characterization of mineral components of coals requires their isolation from organic matter, which would otherwise interfere with phase identification by means of physico-chemical techniques. Low-temperature ashing (LTA) using a cool oxygen plasma is a prospective method to oxidise coal organic matter at low temperatures while keeping the mineral constituents unaltered. In this work the authors used a microwave-excited plasma apparatus for the LTA treatment of lignite samples from the Maritza-Iztok (M-1-1; M-1-2) and Elhovo basins. Minerals were characterised in the LTA residues using FT-IR spectroscopy, X-ray diffraction and scanning electron microscopy combined with energy-dispersive X-ray microanalysis. The advantages and disadvantages of the LTA method are discussed. Results indicate that LTA performs well for the isolation of mineral matter, the ensuing methodology being adequate for the characterisation of Bulgarian lignites. The same mineral constituents (principally clay minerals, quartz, pyrite and carbonates) were identified in all the three studied samples, differences being mainly in their particle size, degree of crystallinity and distribution in the organic matter of coals. 43 refs., 5 figs., 3 tabs.

  8. A catalyst-free synthesis of germanium nanowires obtained by combined X-ray chemical vapour deposition of GeH$_4$ and low-temperature thermal treatment techniques

    Indian Academy of Sciences (India)

    CHIARA DEMARIA; ALDO ARRAIS; PAOLA BENZI; ENRICO BOCCALERI; PAOLA ANTONIOTTI; ROBERTO RABEZZANA; LORENZA OPERTI

    2016-04-01

    A catalyst-free innovative synthesis, by combined X-ray chemical vapour deposition and lowtemperature thermal treatments, which has not been applied since so far to the growth of germanium nanowires (Ge-NWs), produced high yields of the nanoproducts with theGeH4 reactant gas. Nanowires were grown on both surfaces of a conventional deposition quartz substrate. They were featured with high purity and very large aspect ratios (ranging from 100 to 500). Products were characterized by scanning electron microscopy with energy-dispersiveatomic X-ray fluorescence and transmission electron microscopies, X-ray powder diffraction diffractometry, thermogravimetric analysis with differential scanning calorimetry, vibrational infrared and Raman and ultraviolet–visible–near infrared spectroscopies. A quantitative nanowire bundles formation was observed in the lower surface of the quartz substrate positioned over a heating support, whilst spots of nanoflowers constituted by Ge-NWs emerged from a bulk amorphous germanium film matter, deposited on the upper surface of the substrate. Thenanoproducts were characterized by crystalline core morphology, providing semiconductive features and optical band gap of about 0.67 eV. The possible interpretative base-growth mechanisms of the nanowires, stimulated bythe concomitant application of radiant and thermal conditions with no specific added metal catalyst, are hereafter investigated and presented.

  9. 四氯合镉酸正十一烷铵的合成、晶体结构及低温热容%Synthesis, Crystal Structure and Low-temperature Heat Capacities of Bis(n-undecylammonium)tetrachlorocadmiumate

    Institute of Scientific and Technical Information of China (English)

    卢冬飞; 邸友莹; 窦建民

    2012-01-01

    The crystalline bis(n-undecylammonium)tetrachlorocadmiumate (CllH23NH3)2CdCI4(s) [abbre- viated as CllCd(s)] was synthesized. The crystal structure and composition of the complex were determined by single crystal X-ray diffraction, chemical analysis and elementary analysis. The lattice potential energy was calculated to be UpoT= 908.18 kJ·mo1^-1 from crystallographic data. Low-temperature heat capacities of the complex were measured by a precision automatic adiabatic calorimeter over the temperature range from 78 to 395 K. The experimental results show that there are two continuous phase changes appearing in the temperature region. The peak temperatures, molar enthalpies and entropies of two phase transitions for the complex were determined to be: Ttrs,l=(321.88±0.07) K,△trsHm, l=-(37.59±0.17) kJ·mol^-1 and △trsSm,l= (117.24±0.12) J·K^-l·mol^-1 for the first peak; Ttrs,2=(323.81±0.30) K, △trsHm,2 = (12.42± 0.02) kJ·mol^-1 and △trsSm,2=-(38.36±0.09) J·K^-l·mol^-1 for the second peak. Two polynomial equations of the heat capacities as a function of the temperature were fitted by least square method. The smoothed heat capacities and thermodynamic functions relative to 298.15 based on the fitted polynomials. K of the complex were calculated with an interval of 5 K%合成了四氯合镉酸正十一烷铵配合物(C11H23NH3)2CdCl4(s)[简写:C11Cd(s)].用X射线单晶衍射技术、化学分析和元素分析确定其晶体结构和化学组成.利用其晶体学数据计算出晶格能为:UpoT=908.18 kJ·mol^-1.利用精密自动绝热热量计测定了它在78-395K温区的低温热容,结果表明,该配合物在此温区出现两次连续的固-固相转变,计算出两次相变的峰温、摩尔焓及摩尔熵分别为:Ttrs.1=(321.88±0.07)K,△trsHm.1=(37.59±0.17)kJ·mol^-1,△trsSm.1=(117.24±0.12)J·K^-1·mol^-1,Ttrs.2=(323.8l±0.30

  10. Synthesis by-products from the Wacker oxidation of safrole in methanol using rho-benzoquinone and palladium chloride.

    Science.gov (United States)

    Cox, M; Klass, G

    2006-12-20

    This paper reports the identification of a number of by-products, which are produced during the Wacker oxidation of safrole to 3,4-methylenedioxyphenyl-2-propanone (MDP2P) using rho-benzoquinone and palladium chloride when methanol is utilised as the solvent. Also described is the retrieval of these compounds from illicit samples from a clandestine laboratory, which was uncovered in South Australia in September 2003.

  11. Facile synthesis of Pd-based bimetallic nanocrystals and their application as catalysts for methanol oxidation reaction

    Science.gov (United States)

    Xi, Pinxian; Cao, Yang; Yang, Fengchun; Ma, Cai; Chen, Fengjuan; Yu, Sha; Wang, Shuai; Zeng, Zhengzhi; Zhang, Xin

    2013-06-01

    We employed an efficient and facile route to synthesise monodisperse Pd-based bimetallic nanocrystals (MPd: M = Cu, Co and Ni) via a controlled co-reduction of Pd(ii) chloride and M(ii) nitrate at 200-230 °C in the presence of oleylamine (OAm). These monodisperse Pd-based nanocrystals have small dimensions, unique structures and homogeneous morphology, thus exhibit efficient catalytic activities for methanol oxidation in alkaline solution, which is much better than commercial Pd/C with same amount of palladium. The catalytic activities of these nanocrystals followed the order of NiPd/C > CoPd/C > CuPd/C > commercial Pd/C, due to the different synergistic effects. Our results show that these Pd-based bimetallic nanocrystals can be promising as practical catalysts for methanol oxidation reactions and other catalytic reactions in further investigations.We employed an efficient and facile route to synthesise monodisperse Pd-based bimetallic nanocrystals (MPd: M = Cu, Co and Ni) via a controlled co-reduction of Pd(ii) chloride and M(ii) nitrate at 200-230 °C in the presence of oleylamine (OAm). These monodisperse Pd-based nanocrystals have small dimensions, unique structures and homogeneous morphology, thus exhibit efficient catalytic activities for methanol oxidation in alkaline solution, which is much better than commercial Pd/C with same amount of palladium. The catalytic activities of these nanocrystals followed the order of NiPd/C > CoPd/C > CuPd/C > commercial Pd/C, due to the different synergistic effects. Our results show that these Pd-based bimetallic nanocrystals can be promising as practical catalysts for methanol oxidation reactions and other catalytic reactions in further investigations. Electronic supplementary information (ESI) available. See DOI: 10.1039/c3nr00912b

  12. 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.

  13. 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.

  14. Cu-Mo2C/MCM-41: An Efficient Catalyst for the Selective Synthesis of Methanol from CO2

    Directory of Open Access Journals (Sweden)

    Xiaoran Liu

    2016-05-01

    Full Text Available Supported molybdenum carbide (yMo2C/M41 and Cu-promoted molybdenum carbide, using a mechanical mixing and co-impregnation method (xCuyMo2C/M41-M and xCuyMo2C/M41-I on a mesoporous molecular sieve MCM-41, were prepared by temperature-programmed carburization method in a CO/H2 atmosphere at 1073 K, and their catalytic performances were tested for CO2 hydrogenation to form methanol. Both catalysts, which were promoted by Cu, exhibited higher catalytic activity. In comparison to 20Cu20Mo2C/M41-M, the 20Cu20Mo2C/M41-I catalyst exhibited a stronger synergistic effect between Cu and Mo2C on the catalyst surface, which resulted in a higher selectivity for methanol in the CO2 hydrogenation reaction. Under the optimal reaction conditions, the highest selectivity (63% for methanol was obtained at a CO2 conversion of 8.8% over the 20Cu20Mo2C/M41-I catalyst.

  15. 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

  16. Optimization of hydrothermal synthesis of H-ZSM-5 zeolite for dehydration of methanol to dimethyl ether using full factorial design

    Institute of Scientific and Technical Information of China (English)

    Samaneh Hosseini; Majid Taghizadeh; Ali Eliassi

    2012-01-01

    H-ZSM-5 zeolite was synthesized by hydrothermal method.The effects of different synthesis parameters,such as hydrothermal crystallization temperature (170-190 ℃) and Si/Al molar ratio (100-150),on the catalytic performance of the dehydration of methanol to dimethyl ether (DME) over the synthesized H-ZSM-5 zeolite were studied.The catalysts were characterized by N2 adsorption-desorption,XRD,NH3-TPD,TGA/DTA,and SEM techniques.The full factorial design of experiments was applied to the synthesis of H-ZSM-5 zeolite and the effects of synthesis conditions and their interaction on the yield of DME as the response variable were determined.Analysis of variance showed that two variables and their interaction significantly affected the response.According to the experimental results,the optimized catalyst prepared at 170 ℃ with the Si/Al molar ratio of 100 showed the best catalytic performance among the tested H-ZSM-5 zeolite.

  17. 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.

  18. Design and synthesis of Pd-MnO2 nanolamella-graphene composite as a high-performance multifunctional electrocatalyst towards formic acid and methanol oxidation.

    Science.gov (United States)

    Huang, Huajie; Wang, Xin

    2013-07-07

    One great challenge in the development of portable fuel cell systems is to explore novel electrocatalysts with better performance and lower costs. Here we report a facile strategy to fabricate a ternary nanocomposite based on Pd/MnO2 nanolamella-graphene sheets (Pd/MNL/GS) and demonstrate its application as a multifunctional catalyst for both the direct formic acid fuel cell (DFAFC) and direct methanol fuel cell (DMFC). The developed route rationally utilizes graphene as both a green reducing agent in the synthesis of MnO2 nanolamella and a superior supporting material for growing and supporting Pd nanoparticles (NPs). Whether for formic acid oxidation or methanol oxidation, the as-prepared Pd/MNL/GS hybrid has extremely large electrochemically active surface area (ECSA) values and exhibits significantly high forward peak current densities, both of which are nearly 3 times greater than those of the Pd/GS catalyst and 6 times the Pd/Vulcan XC-72 catalyst, revealing that metal Pd can be effectively utilized in the presence of promoter components (MNL and GS). Therefore, such a ternary composite with a sophisticated 2D configuration may bring new design opportunities of high-performance energy conversion devices in the future.

  19. Single Step Bi-reforming and Oxidative Bi-reforming of Methane (Natural Gas) with Steam and Carbon Dioxide to Metgas (CO-2H2) for Methanol Synthesis: Self-Sufficient Effective and Exclusive Oxygenation of Methane to Methanol with Oxygen.

    Science.gov (United States)

    Olah, George A; Goeppert, Alain; Czaun, Miklos; Mathew, Thomas; May, Robert B; Prakash, G K Surya

    2015-07-15

    Catalysts based on suitable metal oxide supports, such as NiO/MgO and CoO/MgO, were shown to be active for single step bi-reforming, the combined steam and dry reforming of methane or natural gas with H2O and CO2 exclusively to metgas (CO-2H2) for efficient methanol synthesis. Reactions were carried out in a tubular flow reactor under pressures up to 42 bar at 830-910 °C. Using a CH4 to steam to CO2 ratio of ∼3:2:1 in the gas feed, the H2/CO ratio of 2:1 was achieved, which is desired for subsequent methanol synthesis. The needed 2/1 steam/CO2 feed ratio together with the reaction heat for the endothermic bi-reforming can be conveniently obtained by the complete combustion of a quarter part of the overall used methane (natural gas) with oxygen of the air (oxidative bi-reforming). Complete combustion of a part of methane followed by bi-reforming leads to the production of metgas (H2/CO in 2:1 mol ratio) for self-sufficient exclusive methanol synthesis. The long sought after but elusive efficient and selective oxygenation of methane to methanol is thus achieved in an effective and economic way without any oxidation byproduct formation according to CH4 + 1/2O2 → CH3OH.

  20. Preparation of silver nanoparticles at low temperature

    Science.gov (United States)

    Mishra, Mini; Chauhan, Pratima

    2016-04-01

    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.