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Sample records for low-temperature catalytic decomposition

  1. Catalytic CVD of SWCNTs at Low Temperatures and SWCNT Devices

    Science.gov (United States)

    Seidel, Robert; Liebau, Maik; Unger, Eugen; Graham, Andrew P.; Duesberg, Georg S.; Kreupl, Franz; Hoenlein, Wolfgang; Pompe, Wolfgang

    2004-09-01

    New results on the planar growth of single-walled carbon nanotubes (SWCNTs) by catalytic chemical vapor deposition (CVD) at low temperatures will be reported. Optimizing catalyst, catalyst support, and growth parameters yields SWCNTs at temperatures as low as 600 °C. Growth at such low temperatures largely affects the diameter distribution since coalescence of the catalyst is suppressed. A phenomenological growth model will be suggested for CVD growth at low temperatures. The model takes into account surface diffusion and is an alternative to the bulk diffusion based vapor-liquid-solid (VLS) model. Furthermore, carbon nanotubes field effect transistors based on substrate grown SWCNTs will be presented. In these devices good contact resistances could be achieved by electroless metal deposition or metal evaporation of the contacts.

  2. Programming Enhancements for Low Temperature Thermal Decomposition Workstation

    Energy Technology Data Exchange (ETDEWEB)

    Igou, R.E.

    1998-10-01

    This report describes a new control-and-measurement system design for the Oak Ridge Y-12 Plant's Low Temperature Thermal Decomposition (LTTD) process. The new design addresses problems with system reliability stemming from equipment obsolescence and addresses specific functional improvements that plant production personnel have identified, as required. The new design will also support new measurement techniques, which the Y-12 Development Division has identified for future operations. The new techniques will function in concert with the original technique so that process data consistency is maintained.

  3. Low temperature catalytic combustion of natural gas - hydrogen - air mixtures

    Energy Technology Data Exchange (ETDEWEB)

    Newson, E.; Roth, F. von; Hottinger, P.; Truong, T.B. [Paul Scherrer Inst. (PSI), Villigen (Switzerland)

    1999-08-01

    The low temperature catalytic combustion of natural gas - air mixtures would allow the development of no-NO{sub x} burners for heating and power applications. Using commercially available catalysts, the room temperature ignition of methane-propane-air mixtures has been shown in laboratory reactors with combustion efficiencies over 95% and maximum temperatures less than 700{sup o}C. After a 500 hour stability test, severe deactivation of both methane and propane oxidation functions was observed. In cooperation with industrial partners, scaleup to 3 kW is being investigated together with startup dynamics and catalyst stability. (author) 3 figs., 3 refs.

  4. Catalytic Performance of Fe/H-beta Catalyst Modified by Mn for NOx Decomposition at Low Temperature%Mn改性Fe/H-beta催化剂的低温催化分解NOx的研究

    Institute of Scientific and Technical Information of China (English)

    潘华; 宋华丰

    2012-01-01

    通过Mn改性制备了Fe和Mn的质量比为1且Fe和Mn的质量分数均为5% (5%Fe-5%Mn/H-beta)的催化剂,通过氢气程序升温还原(H2-TPR)比较分析了Fe-Mn/H-beta、Fe/H-beta和Mn/H-beta催化剂中Fe和Mn的化学形态,考察了O2、SO2和H2O等反应条件对Fe-Mn/H-beta催化剂低温催化分解NOx的影响.结果表明,相比Fe/H-beta和Mn/H-beta,Fe-Mn/H-beta 催化剂在富氧和低温条件下具有较好的催化活性,其中623 K下催化剂的活性最高,NOx的转化率达到45%左右.Fe-Mn/H-beta催化剂中Fe和Mn的共存提高了Fe2O3和MnO2的含量.氧的存在促进了NOx催化分解,水蒸气和SO2对NOx催化分解有一定的抑制作用.%Direct decomposition of NOX was investigated with 5% Fe-5% Mn/H-beta catalysts with equal weight of Mn and Fe. The chemical states of Fe and Mn in Fe-Mn/H-beta, Fe/H-be-ta, and Mn/H-beta catalysts were characterized by H2-TPR. The effects of O2, SO2 and H20 on decomposition of NOX at low temperature with 5 %Fe-5% Mn/H-beta catalysts were examined. The results indicate that the activity of Fe-Mn/H-beta is higher than that of Fe/H-beta or Mn/H-beta at rich oxygen and low temperature from 573 K to 673 K. The maximum NO* conversion is about 45% with 5 %Fe-5%Mn/H-beta at 623 K. The presence of Fe in Fe-Mn/H-beta enhances the transformation of Mn3+ ions into Mn4+ ions, and the addition of Mn increases the amount of Fe2O3 in Fe-Mn/H-beta. In addition, O2 inhibition is not observed in NOX decomposition with Fe-Mn/H-beta while the presence of H2O and SO2 inhibits the activity of Fe-Mn/H-beta.

  5. Low-temperature catalytic gasification of wet industrial wastes

    Energy Technology Data Exchange (ETDEWEB)

    Elliott, D C; Neuenschwander, G G; Baker, E G; Sealock, Jr, L J; Butner, R S

    1991-04-01

    Bench-scale reactor tests are in progress at Pacific Northwest Laboratory to develop a low-temperature, catalytic gasification system. The system, licensed under the trade name Thermochemical Environmental Energy System (TEES{reg sign}), is designed for treating a wide variety of feedstocks ranging from dilute organics in water to waste sludges from food processing. This report describes a test program which used a continuous-feed tubular reactor. This test program is an intermediate stage in the process development. The reactor is a laboratory-scale version of the commercial concept as currently envisioned by the process developers. An energy benefit and economic analysis was also completed on the process. Four conceptual commercial installations of the TEES process were evaluated for three food processing applications and one organic chemical manufacturing application. Net energy production (medium-Btu gas) was achieved in all four cases. The organic chemical application was found to be economically attractive in the present situation. Based on sensitivity studies included in the analysis, the three food processing cases will likely become attractive in the near future as waste disposal regulations tighten and disposal costs increase. 21 refs., 2 figs., 9 tabs.

  6. Low-temperature catalytic preparation of multi-wall MoS2 nanotubes

    Institute of Scientific and Technical Information of China (English)

    2003-01-01

    In the catalytic reduction atmosphere of H2+CH4+C4H4S, the ball-milled precursor (NH4)2MoS4 is heated to 300(C for decomposition. The as-synthesized product is characterized by XRD, SEM, TEM, HRTEM, EDX, and BET. The results show that multi-wall MoS2 nanotubes are obtained. The length of the nanotubes is around 3-5 (m. The diameters of the nanotubes are homogeneous, with an inner diameter of (15 nm, an outer diameter of (30 nm, and an interlayer (002) d-spacing of 0.63 nm. This catalytic thermal reaction occurring at low temperatures is important for the large-scale preparation of similar transition-metal disulfide nanotubes.

  7. Hydrogen peroxide catalytic decomposition

    Science.gov (United States)

    Parrish, Clyde F. (Inventor)

    2010-01-01

    Nitric oxide in a gaseous stream is converted to nitrogen dioxide using oxidizing species generated through the use of concentrated hydrogen peroxide fed as a monopropellant into a catalyzed thruster assembly. The hydrogen peroxide is preferably stored at stable concentration levels, i.e., approximately 50%-70% by volume, and may be increased in concentration in a continuous process preceding decomposition in the thruster assembly. The exhaust of the thruster assembly, rich in hydroxyl and/or hydroperoxy radicals, may be fed into a stream containing oxidizable components, such as nitric oxide, to facilitate their oxidation.

  8. Ultraviolet surface plasmon-mediated low temperature hydrazine decomposition

    Energy Technology Data Exchange (ETDEWEB)

    Peng, Siying; Sheldon, Matthew T.; Atwater, Harry A. [Thomas J. Watson Laboratories of Applied Physics, California Institute of Technology, Pasadena, California 91125 (United States); Liu, Wei-Guang; Jaramillo-Botero, Andres; Goddard, William Andrew [Materials and Process Simulation Center, California Institute of Technology, Pasadena, California 91125 (United States)

    2015-01-12

    Conventional methods require elevated temperatures in order to dissociate high-energy nitrogen bonds in precursor molecules such as ammonia or hydrazine used for nitride film growth. We report enhanced photodissociation of surface-absorbed hydrazine (N{sub 2}H{sub 4}) molecules at low temperature by using ultraviolet surface plasmons to concentrate the exciting radiation. Plasmonic nanostructured aluminum substrates were designed to provide resonant near field concentration at λ = 248 nm (5 eV), corresponding to the maximum optical cross section for hydrogen abstraction from N{sub 2}H{sub 4}. We employed nanoimprint lithography to fabricate 1 mm × 1 mm arrays of the resonant plasmonic structures, and ultraviolet reflectance spectroscopy confirmed resonant extinction at 248 nm. Hydrazine was cryogenically adsorbed to the plasmonic substrate in a low-pressure ambient, and 5 eV surface plasmons were resonantly excited using a pulsed KrF laser. Mass spectrometry was used to characterize the photodissociation products and indicated a 6.2× overall enhancement in photodissociation yield for hydrazine adsorbed on plasmonic substrates compared with control substrates. The ultraviolet surface plasmon enhanced photodissociation demonstrated here may provide a valuable method to generate reactive precursors for deposition of nitride thin film materials at low temperatures.

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

    Directory of Open Access Journals (Sweden)

    TsungYu Lee

    2016-05-01

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

  10. Direct decomposition of nitric oxide in low temperature over iron-based perovskite-type catalyst modified by Ru

    Institute of Scientific and Technical Information of China (English)

    LI Li; ZHANG Mi-lin; YUAN Fu-long; SHI Ke-ying; ZHANG Guo; ZHANG Dan

    2006-01-01

    Iron-based perovskite-type compounds modified by Ru were prepared through sol-gel process to study its catalytic activity of NOx direct decomposition at low temperature and evaluate the conversion of NO under the experimental conditions. The catalytic activity of La0.9Ce0.1Fe0.8-nCo0.2RunO3 ( n = 0.01,0.03,0.05,0.07,0.09)series for the NO, NO-CO two components, CO-HC-NO three components were also analyzed. The catalytic investigation evidenced that the presence of Ru is necessary for making highly activity in decomposition of nitric oxide even at low temperature (400 ℃ ) and La0.9Ce0.9Fe0.75Co0.2Ru0.05O3( n = 0. 05 ) has better activity in all the samples, the conversion of it is 58.5%. With the reducing gas (CO, C3 H6 )added into the gas, the catalyst displayed very high activity in decomposition of NO and the conversion of it is 80% and 92. 5% separately.

  11. Polymer and Membrane Design for Low Temperature Catalytic Reactions.

    Science.gov (United States)

    Villalobos, Luis Francisco; Xie, Yihui; Nunes, Suzana Pereira; Peinemann, Klaus-Viktor

    2016-04-01

    Catalytically active asymmetric membranes have been developed with high loadings of palladium nanoparticles located solely in the membrane's ultrathin skin layer. The manufacturing of these membranes requires polymers with functional groups, which can form insoluble complexes with palladium ions. Three polymers have been synthesized for this purpose and a complexation/nonsolvent induced phase separation followed by a palladium reduction step is carried out to prepare such membranes. Parameters to optimize the skin layer thickness and porosity, the palladium loading in this layer, and the palladium nanoparticles size are determined. The catalytic activity of the membranes is verified with the reduction of a nitro-compound and with a liquid phase Suzuki-Miyaura coupling reaction. Very low reaction times are observed.

  12. Polymer and Membrane Design for Low Temperature Catalytic Reactions

    KAUST Repository

    Villalobos, Luis Francisco

    2016-02-29

    Catalytically active asymmetric membranes have been developed with high loadings of palladium nanoparticles located solely in the membrane\\'s ultrathin skin layer. The manufacturing of these membranes requires polymers with functional groups, which can form insoluble complexes with palladium ions. Three polymers have been synthesized for this purpose and a complexation/nonsolvent induced phase separation followed by a palladium reduction step is carried out to prepare such membranes. Parameters to optimize the skin layer thickness and porosity, the palladium loading in this layer, and the palladium nanoparticles size are determined. The catalytic activity of the membranes is verified with the reduction of a nitro-compound and with a liquid phase Suzuki-Miyaura coupling reaction. Very low reaction times are observed. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  13. Low temperature catalytic reforming of heptane to hydrogen and syngas

    Directory of Open Access Journals (Sweden)

    M.E.E. Abashar

    2016-09-01

    Full Text Available The production of hydrogen and syngas from heptane at a low temperature is studied in a circulating fast fluidized bed membrane reactor (CFFBMR. A thin film of palladium-based membrane is employed to the displacement of the thermodynamic equilibrium for high conversion and yield. A mathematical model is developed to simulate the reformer. A substantial improvement of the CFFBMR is achieved by implementing the thin hydrogen membrane. The results showed that almost complete conversion of heptane and 46.25% increase of exit hydrogen yield over the value without membrane are achieved. Also a wide range of the H2/CO ratio within the recommended industrial range is obtained. The phenomena of high spikes of maximum nature at the beginning of the CFFBMR are observed and explanation offered. The sensitivity analysis results have shown that the increase of the steam to carbon feed ratio can increase the exit hydrogen yield up to 108.29%. It was found that the increase of reaction side pressure at a high steam to carbon feed ratio can increase further the exit hydrogen yield by 49.36% at a shorter reactor length. Moreover, the increase of reaction side pressure has an important impact in a significant decrease of the carbon dioxide and this is a positive sign for clean environment.

  14. 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.

  15. Conversion of elemental mercury with a novel membrane catalytic system at low temperature.

    Science.gov (United States)

    Guo, Yongfu; Yan, Naiqiang; Yang, Shijian; Liu, Ping; Wang, Juan; Qu, Zan; Jia, Jinping

    2012-04-30

    A unique assembly, which integrated membrane delivery for oxidants with catalytic oxidation (MDCOs), was employed to convert elemental mercury (Hg(0)) to its oxidized form at low temperature (around 150 °C). MnO(x) was used as the main catalytic component in MDCOs with Mo and/or Ru to improve the catalytic activity. The MDCOs was proved to be very effective for the conversion of Hg(0) compared with the traditional catalytic oxidation mode (TCO). The analysis of speciation for Hg after catalytic oxidation showed that there was mainly mercury (II) chloride. The addition of transition metals of Mo and Ru obviously improved the conversion of Hg(0) to Hg(2+) and enhanced the activity of the MDCOs at low temperature, and the conversion efficiency of Hg(0) reached 95% with Mo-Ru-Mn catalyst and 8 ppmv HCl. The inhibition of SO(2) to Hg(0) conversion in the MDCOs was insignificant. The Hg(0) removal exceeded 80% even if the concentration of SO(2) reached 1000 ppmv. The results also indicated that the Deacon reaction with the yield of Cl(2) were significantly improved after modified, and MDCOs with Mo-Ru-Mn catalyst can work efficiently at low temperature. Copyright © 2012 Elsevier B.V. All rights reserved.

  16. Toward improved catalytic low-temperature NOx removal in diesel-powered vehicles.

    Science.gov (United States)

    Klingstedt, Fredrik; Arve, Kalle; Eränen, Kari; Murzin, Dmitry Yu

    2006-04-01

    The potential of different catalytic after treatment techniques to meet future diesel emission standards, which are strongly shifted toward urban driving conditions including cold start, are critically discussed in this Account and evaluated for their suitability for commercial applications. The dominating techniques in this field are NO(x) storage, urea-selective catalytic reduction (SCR), and HC-SCR. Each of these techniques have significant disadvantages such as sulfur sensitiveness and regeneration requirements of NO(x)-storage materials, infrastructure issues and formation of ammonium nitrate (at low temperatures) for urea-SCR, and low-temperature activity of HC-SCR catalysts. Ways to overcome these disadvantages in commercial applications may involve optimized regeneration strategies, reactor modifications, flow reversal, closed-loop NO(x) feedback systems, nonthermal plasma, and/or hydrogen-assisted catalyses, etc.

  17. Catalytic ozone oxidation of benzene at low temperature over MnOx/Al-SBA-16 catalyst.

    Science.gov (United States)

    Park, Jong Hwa; Kim, Ji Man; Jin, Mingshi; Jeon, Jong-Ki; Kim, Seung-Soo; Park, Sung Hoon; Kim, Sang Chai; Park, Young-Kwon

    2012-01-05

    The low-temperature catalytic ozone oxidation of benzene was investigated. In this study, Al-SBA-16 (Si/Al = 20) that has a three-dimensional cubic Im3m structure and a high specific surface area was used for catalytic ozone oxidation for the first time. Two different Mn precursors, i.e., Mn acetate and Mn nitrate, were used to synthesize Mn-impregnated Al-SBA-16 catalysts. The characteristics of these two catalysts were investigated by instrumental analyses using the Brunauer-Emmett-Teller method, X-ray diffraction, X-ray photoelectron spectroscopy, and temperature-programmed reduction. A higher catalytic activity was exhibited when Mn acetate was used as the Mn precursor, which is attributed to high Mn dispersion and a high degree of reduction of Mn oxides formed by Mn acetate than those formed by Mn nitrate.

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

    Science.gov (United States)

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

    2016-06-22

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

  19. Temperature sensitivity of soil organic matter decomposition was strongly affected by land use under low temperature

    Science.gov (United States)

    Zang, Huadong; Blagodatskaya, Evgenia; Xu, Xingliang; Kuzyakov, Yakov

    2017-04-01

    The temperature sensitivity of soil organic matter (SOM) decomposition (often measured as Q10 value) is important for predicting global carbon (C) stocks under warming scenarios. However, the effects of land use and labile substrates on Q10 value remain unclear. We investigated CO2 emission from soils of three land use types (i.e. grassland, cropland and bare fallow) at five temperatures (0, 10, 20, 30 and 40 °C) with or without labile C (14C-glucose) addition. The CO2 efflux from SOM increased with temperature and was 43, 21 and 9 times higher at 40 °C than at 0 °C in grassland, cropland and bare fallow soils, respectively. High temperature strongly increased the cumulative priming effect (PE) in grassland soil (from 0.1 to 4.7 mg g-1 SOC), while the PE in cropland and bare fallow was not sensitive to warming. The Q10 of SOM (2.3-6) was higher at low temperature (0-10 °C) and decreased strongly to Q10 = 1.7-2.0 with temperature increase. The Q10 of SOM in grassland was 1.6 and 2.7 times higher than cropland and bare fallow at low temperature, respectively. Labile C addition decreased the Q10 of SOM in grassland and cropland, but increased it in bare fallow, especially under low temperature. Overall, temperature sensitivity of SOM was strongly affected by land use at low temperature and was relatively stable in high temperature (> 10°C). Labile C addition mainly affected temperature sensitivity of SOM at lower temperature, which decreased in grassland and cropland, and increased in bare fallow. These findings indicate that global warming may result in regionally variable responses in soil respiration, with colder climates being considerably more responsive to increased ambient temperatures.

  20. Low-temperature catalytic oxidation of NO over Mn-Ce-O_x catalyst

    Institute of Scientific and Technical Information of China (English)

    李华; 唐晓龙; 易红宏; 于丽丽

    2010-01-01

    A series of manganese-cerium oxide catalysts were prepared by different methods and used for low-temperature catalytic oxidation of NO in the presence of excess O2.Their surface properties were evaluated by means of BET and were characterized by using scanning electron microscopy(SEM) and X-ray diffractometer(XRD).The activity test of Mn-Ce-Ox catalysts showed that addition of Ce enhanced the activities of NO oxidation.The most active catalysts with a molar Ce/(Mn+Ce) ratio of 0.3 were prepared by co-precip...

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

    Science.gov (United States)

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

    2007-01-21

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

  2. Adsorption and Decomposition of EtO on Cl-modified Ag(111)at Low Temperatures

    Institute of Scientific and Technical Information of China (English)

    吴凯; 王德峥; 魏绪明; 曹玉明; 郭燮贤

    1994-01-01

    The adsorption and decomposition of ethylene oxide(EtO)on Cl-modified and oxygen-pre-covered Ag(111)at low temperatures with high resolution electron energy loss spectroscopy(HREELS)arestudied.At 140 K,EtO is molecularly adsorbed on the surface.At above 230K.with atomic oxygen on thesurface,a small amount of EtO decomposes into ethylene and is oxidized to produce some oxidation productsas water,etc.while with dioxygen on the surface,a large amount of EtO decomposes into ethylene and isoxidized to produce large amounts of oxidation products like water and so on.The experimental resultsshowed that chlorine can,on the one hand,decrease the adsorption amount of EtO and,on the other hand,inhibit the further oxidation of EtO.

  3. Surface Structure and Catalytic Performance of Ni-Fe Catalyst for Low-Temperature CO Hydrogenation

    Directory of Open Access Journals (Sweden)

    Fanhui Meng

    2014-01-01

    Full Text Available Catalysts 16NixFe/Al2O3 (x is 0, 1, 2, 4, 6, 8 were prepared by incipient wetness impregnation method and the catalytic performance for the production of synthetic natural gas (SNG from CO hydrogenation in slurry-bed reactor were studied. The catalysts were characterized by BET, XRD, UV-Vis DRS, H2-TPR, CO-TPD, and XPS, and the results showed that the introduction of iron improved the dispersion of Ni species, weakened the interaction between Ni species and support and decreased the reduction temperature and that catalyst formed Ni-Fe alloy when the content of iron exceeded 2%. Experimental results revealed that the addition of iron to the catalyst can effectively improve the catalytic performance of low-temperature CO methanation. Catalyst 16Ni4Fe/Al2O3 with the iron content of 4% exhibited the best catalytic performance, the conversion of CO and the yield of CH4 reached 97.2% and 84.9%, respectively, and the high catalytic performance of Ni-Fe catalyst was related to the property of formed Ni-Fe alloy. Further increase of iron content led to enhancing the water gas shift reaction.

  4. Low temperature platinum atomic layer deposition on nylon-6 for highly conductive and catalytic fiber mats

    Energy Technology Data Exchange (ETDEWEB)

    Mundy, J. Zachary; Shafiefarhood, Arya; Li, Fanxing; Khan, Saad A.; Parsons, Gregory N., E-mail: gnp@ncsu.edu [Department of Chemical and Biomolecular Engineering, North Carolina State University, Engineering Building I, 911 Partners Way, Raleigh, North Carolina 27695-7905 (United States)

    2016-01-15

    Low temperature platinum atomic layer deposition (Pt-ALD) via (methylcyclopentadienyl)trimethyl platinum and ozone (O{sub 3}) is used to produce highly conductive nonwoven nylon-6 (polyamide-6, PA-6) fiber mats, having effective conductivities as high as ∼5500–6000 S/cm with only a 6% fractional increase in mass. The authors show that an alumina ALD nucleation layer deposited at high temperature is required to promote Pt film nucleation and growth on the polymeric substrate. Fractional mass gain scales linearly with Pt-ALD cycle number while effective conductivity exhibits a nonlinear trend with cycle number, corresponding to film coalescence. Field-emission scanning electron microscopy reveals island growth mode of the Pt film at low cycle number with a coalesced film observed after 200 cycles. The metallic coating also exhibits exceptional resistance to mechanical flexing, maintaining up to 93% of unstressed conductivity after bending around cylinders with radii as small as 0.3 cm. Catalytic activity of the as-deposited Pt film is demonstrated via carbon monoxide oxidation to carbon dioxide. This novel low temperature processing allows for the inclusion of highly conductive catalytic material on a number of temperature-sensitive substrates with minimal mass gain for use in such areas as smart textiles and flexible electronics.

  5. Study of nitric oxide catalytic oxidation on manganese oxides-loaded activated carbon at low temperature

    Science.gov (United States)

    You, Fu-Tian; Yu, Guang-Wei; Wang, Yin; Xing, Zhen-Jiao; Liu, Xue-Jiao; Li, Jie

    2017-08-01

    Nitric oxide (NO) is an air pollutant that is difficult to remove at low concentration and low temperature. Manganese oxides (MnOx)-loaded activated carbon (MLAC) was prepared by a co-precipitation method and studied as a new catalyst for NO oxidation at low temperature. Characterization of MLAC included X-ray diffraction (XRD), scanning electron microscopy (SEM), N2 adsorption/desorption and X-ray photoelectron spectroscopy (XPS). Activity tests demonstrated the influence of the amount of MnOx and the test conditions on the reaction. MLAC with 7.5 wt.% MnOx (MLAC003) exhibits the highest NO conversion (38.7%) at 1000 ppm NO, 20 vol.% O2, room temperature and GHSV ca. 16000 h-1. The NO conversion of MLAC003 was elevated by 26% compared with that of activated carbon. The results of the MLAC003 activity test under different test conditions demonstrated that NO conversion is also influenced by inlet NO concentration, inlet O2 concentration, reaction temperature and GHSV. The NO adsorption-desorption process in micropores of activated carbon is fundamental to NO oxidation, which can be controlled by pore structure and reaction temperature. The activity elevation caused by MnOx loading is assumed to be related to Mn4+/Mn3+ ratio. Finally, a mechanism of NO catalytic oxidation on MLAC based on NO adsorption-desorption and MnOx lattice O transfer is proposed.

  6. Testing marine shales' ability to generate catalytic gas at low temperature

    Science.gov (United States)

    Wei, L.; Schimmelmann, A.; Drobniak, A.; Sauer, P. E.; Mastalerz, M.

    2013-12-01

    Hydrocarbon gases are generally thought to originatevia low-temperature microbial or high-temperature thermogenicpathways (Whiticar, 1996) that can be distinguished by compound-specific hydrogen and carbon stable isotope ratios. An alternative low-temperature catalytic pathway for hydrocarbon generation from sedimentary organic matter has been proposed to be active at temperatures as low as 50oC (e.g.,Mango and Jarvie,2009,2010; Mango et al., 2010; Bartholomew et al., 1999). This hypothesis, however, still requires rigoroustesting by independent laboratory experiments.The possibility of catalytic generation of hydrocarbons in some source rocks (most likely in relatively impermeable and organic-rich shales where reduced catalytic centers can be best preserved) would offer an explanation for the finding of gas of non-microbial origin in formations that lack the thermal maturity for generating thermogenic gas.It is unknown whether catalytically generated methane would be isotopically different from thermogenicmethane (δ13CCH4>-50‰, δ2HCH4from -275‰ to -100‰) ormicrobially generated methane (δ13CCH4from -40‰ to -110‰, δ2HCH4from -400‰to -150‰) (Whiticar, 1998). In order to test for catalytic gas generationin water-wet shales and coals, we are conductinglaboratory experiments at three temperatures (60°C, 100°C, 200°C)and three pressures (ambient pressure, 107 Pa, 3x107 Pa)over periods of six months to several years. So far, our longest running experiments have reached one year. We sealed different types of thermally immature, pre-evacuatedshales (Mowry, New Albany, and Mahoganyshales) and coals (SpringfieldCoal and Wilcoxlignite)with isotopically defined waters in gold cells in the absence of elemental oxygen.Preliminary results show that these samples, depending on conditions, can generate light hydrocarbon gases (methane, ethane and propane) and CO2. Methane, CO2, and traces of H2havebeen generated at 60°C, whereas experiments at 100°C and 200

  7. Catalytic activity of carbons for methane decomposition reaction

    Energy Technology Data Exchange (ETDEWEB)

    Muradov, Nazim; Smith, Franklyn; T-Raissi, Ali [Florida Solar Energy Center, University of Central Florida, 1679 Clearlake Road, Cocoa, FL 32922 (United States)

    2005-05-15

    Catalytic decomposition of methane is an environmentally attractive approach to CO{sub 2}-free production of hydrogen. The objective of this work is to evaluate catalytic activity of a wide range of carbon materials for methane decomposition reaction and determine major factors governing their activity. It was demonstrated that the catalytic activity of carbon materials for methane decomposition is mostly determined by their structural and surface properties. Kinetics of methane decomposition reaction over disordered (amorphous) carbons such as carbon black and activated carbon were determined. The mechanism of carbon-catalyzed methane decomposition reaction and the nature of active sites on the carbon surface are discussed in this paper.

  8. Low-temperature catalytic gasification of wet industrial wastes. FY 1991--1992 interim report

    Energy Technology Data Exchange (ETDEWEB)

    Elliott, D.C.; Neuenschwander, G.G.; Hart, T.R.; Phelps, M.R.; Sealock, L.J. Jr.

    1993-07-01

    A catalytic gasification system operating in a pressurized water environment has been developed and refined at Pacific Northwest Laboratory (PNL) for over 12 years. Initial experiments were aimed at developing kinetics information for steam gasification of biomass in the presence of catalysts. The combined use of alkali and metal catalysts was reported for gasification of biomass and its components at low temperatures (350{degrees}C to 450{degrees}C). From the fundamental research evolved the concept of a pressurized, catalytic gasification system for converting wet biomass feedstocks to fuel gas. Extensive batch reactor testing and limited continuous reactor system (CRS) testing were undertaken in the development of this system under sponsorship of the US Department of Energy. A wide range of biomass feedstocks were tested, and the importance of the nickel metal catalyst was identified. Specific use of this process for treating food processing wastes was also studied. The concept application was further expanded to encompass cleanup of hazardous wastewater streams, and results were reported for batch reactor tests and continuous reactor tests. Ongoing work at PNL focuses on refining the catalyst and scaling the system to long-term industrial needs. The process is licensed as the Thermochemical Environmental Energy System (TEES{reg_sign}) to Onsite*Ofsite, Inc., of Duarte, California. This report is a follow-on to the 1989--90 interim report [Elliott et al. 1991], which reviewed the results of the studies conducted with a fixed-bed, continuous-feed, tubular reactor. The discussion here provides an overview of experiments on the wide range of potential feedstock materials conducted in a batch reactor; development of new catalyst materials; and tests performed in continuous-flow reactors at three scales. The appendices contain the history and background of the process development, as well as more detailed descriptions and results of the recent studies.

  9. Low-temperature catalytic gasification of wet industrial wastes. FY 1993--1994 interim report

    Energy Technology Data Exchange (ETDEWEB)

    Elliott, D.C.; Hart, T.R.; Neuenschwander, G.G.; Deverman, G.S.; Werpy, T.A.; Phelps, M.R.; Baker, E.G.; Sealock, L.J. Jr.

    1995-03-01

    Process development research is continuing on a low-temperature, catalytic gasification system that has been demonstrated to convert organics in water (dilute or concentrated) to useful and environmentally safe gases. The system, licensed under the trade name Thermochemical Environmental Energy System (TEESO), treats a wide variety of feedstocks ranging from hazardous organics in water to waste sludges from food processing. The current research program is focused on the use of continuous-feed, tubular reactors systems for testing catalysts and feedstocks in the process. A range of catalysts have been tested, including nickel and other base metals, as well as ruthenium and other precious metals. Results of extensive testing show that feedstocks, ranging from 2% para-cresol in water to potato waste and spent grain, can be processed to > 99% reduction of chemical oxygen demand (COD). The product fuel gas contains from 40% up to 75% methane, depending on the feedstock. The balance of the gas is mostly carbon dioxide with < 5% hydrogen and usually < 1% ethane and higher hydrocarbons. The byproduct water stream carries residual organics from 10 to 1,000 mg/l COD, depending on the feedstock. The level of development of TEES has progressed to the initial phases of industrial process demonstration. Testing of industrial waste streams is under way at both the bench scale and engineering scale of development.

  10. Bench-scale reactor tests of low-temperature, catalytic gasification of wet, industrial wastes

    Energy Technology Data Exchange (ETDEWEB)

    Elliott, D.C.; Neuenschwander, G.G.; Baker, E.G.; Butner, R.S.; Sealock, L.J.

    1990-04-01

    Bench-scale reactor tests are under way at Pacific Northwest Laboratory to develop a low-temperature, catalytic gasification system. The system, licensed under the trade name Thermochemical Environmental Energy System (TEES{reg sign}), is designed for to a wide variety of feedstocks ranging from dilute organics in water to waste sludges from food processing. The current research program is focused on the use of a continuous-feed, tubular reactor. The catalyst is nickel metal on an inert support. Typical results show that feedstocks such as solutions of 2% para-cresol or 5% and 10% lactose in water or cheese whey can be processed to >99% reduction of chemical oxygen demand (COD) at a rate of up to 2 L/hr. The estimated residence time is less than 5 min at 360{degree}C and 3000 psig, not including 1 to 2 min required in the preheating zone of the reactor. The liquid hourly space velocity has been varied from 1.8 to 2.9 L feedstock/L catalyst/hr depending on the feedstock. The product fuel gas contains 40% to 55% methane, 35% to 50% carbon dioxide, and 5% to 10% hydrogen with as much as 2% ethane, but less than 0.1% ethylene or carbon monoxide, and small amounts of higher hydrocarbons. The byproduct water stream carries residual organics amounting to less than 500 mg/L COD. 9 refs., 1 fig., 4 tabs.

  11. DEVELOPMENT OF HIGH ACTIVITY, COAL DERIVED, PROMOTED CATALYTIC SYSTEMS FOR NOx REDUCTION AT LOW TEMPERATURES

    Energy Technology Data Exchange (ETDEWEB)

    Joseph M. Calo

    1998-12-31

    This project is directed at an investigation of catalytic NO{sub x} reduction mechanisms on coal-derived, activated carbon supports at low temperatures. Promoted carbon systems offer some potentially significant advantages for heterogeneous NO{sub x} reduction. These include: low cost; high activity at low temperatures, which minimizes carbon loss; oxygen resistance; and a support material which can be engineered with respect to porosity, transport and catalyst dispersion characteristics. During the reporting period, the following has been accomplished: (1) A MS-TGA (mass spectrometric-thermogravimetric analysis) apparatus, which is one of the primary instruments that will be used in these studies, has been refurbished and modified to meet the requirements of this project. A NO{sub x} chemiluminescence analyzer (ThermoElectron, Model 10) has been added to the instrument to monitor NO{sub x} concentrations in the feed and product streams. Computer control and data acquisition system has been updated and modified to accommodate the requirements of the specific types of experiments planned. The diffusion pumps used to maintain vacuum for the mass spectrometer system have been replaced with turbomolecular pumps (Varian 300 HT). (2) A packed bed reactor/gas flow system has been assembled for performing reactivity studies. This system employs a Kin-Tek gas calibration/mixing system for varying NO and CO concentrations in the feed gas to the packed bed, a NO{sub x} chemiluminescence analyzer (ThermoElectron, Model 10), and a quadrupole mass spectrometer (Dycor). This system is required for steady-state reactivity studies, as well as mechanistic studies on the effects of NO and CO in the gas phase on intermediate oxygen surface complex populations on the carbon substrates. (3) Work has continued on the application of contrast matching, small angle neutron scattering to the characterization and development of char porosity. Contrast matching with perdeuterated toluene has

  12. Characterisation of Zinc Oxide and Cadmium Oxide Nanostructures Obtained from the Low Temperature Thermal Decomposition of Inorganic Precursors

    OpenAIRE

    K. Kalpanadevi; Sinduja, C. R.; Manimekalai, R.

    2013-01-01

    Low temperature syntheses of zinc oxide and cadmium oxide nanoparticles are reported in this paper. The inorganic precursor complexes were prepared and characterised by hydrazine and metal analyses, infrared spectral analysis, and thermal analysis. Using appropriate annealing conditions, zinc oxide and cadmium oxide nanoparticles of average particle sizes around 13 nm and 30 nm were synthesised from the precursors by a simple thermal decomposition route. The synthesised nanoparticles were cha...

  13. Simultaneous Removal of NOx and Mercury in Low Temperature Selective Catalytic and Adsorptive Reactor

    Energy Technology Data Exchange (ETDEWEB)

    Neville G. Pinto; Panagiotis G. Smirniotis

    2006-03-31

    The results of a 18-month investigation to advance the development of a novel Low Temperature Selective Catalytic and Adsorptive Reactor (LTSCAR), for the simultaneous removal of NO{sub x} and mercury (elemental and oxidized) from flue gases in a single unit operation located downstream of the particulate collectors, are reported. In the proposed LTSCAR, NO{sub x} removal is in a traditional SCR mode but at low temperature, and, uniquely, using carbon monoxide as a reductant. The concomitant capture of mercury in the unit is achieved through the incorporation of a novel chelating adsorbent. As conceptualized, the LTSCAR will be located downstream of the particulate collectors (flue gas temperature 140-160 C) and will be similar in structure to a conventional SCR. That is, it will have 3-4 beds that are loaded with catalyst and adsorbent allowing staged replacement of catalyst and adsorbent as required. Various Mn/TiO{sub 2} SCR catalysts were synthesized and evaluated for their ability to reduce NO at low temperature using CO as the reductant. It has been shown that with a suitably tailored catalyst more than 65% NO conversion with 100% N{sub 2} selectivity can be achieved, even at a high space velocity (SV) of 50,000 h-1 and in the presence of 2 v% H{sub 2}O. Three adsorbents for oxidized mercury were developed in this project with thermal stability in the required range. Based on detailed evaluations of their characteristics, the mercaptopropyltrimethoxysilane (MPTS) adsorbent was found to be most promising for the capture of oxidized mercury. This adsorbent has been shown to be thermally stable to 200 C. Fixed-bed evaluations in the targeted temperature range demonstrated effective removal of oxidized mercury from simulated flue gas at very high capacity ({approx}>58 mg Hg/g adsorbent). Extension of the capability of the adsorbent to elemental mercury capture was pursued with two independent approaches: incorporation of a novel nano-layer on the surface of the

  14. Low temperature selective catalytic reduction of NO over Pt-Zeolite using hydrogen

    Energy Technology Data Exchange (ETDEWEB)

    Ramachandran, B.; Choi, S.; Herman, R.G.; Stenger, H.G.; Sale, J.W.; Lyman, C.E.

    1999-07-01

    It has been found that platinum based zeolite catalysts are very active for the selective catalytic reduction (SCR) of nitrogen oxides (NOx) with hydrogen at low reaction temperatures, i.e. 200 C. The catalysts are active for NOx reduction in the presence of oxygen, water vapor (steam), and sulfur dioxide. It is notable that the use of hydrogen instead of ammonia as the reducing agent greatly reduces the formation of N{sub 2}O from NO over these low temperature catalysts. A testing protocol was established for testing NO reduction catalysts, and the reaction conditions utilized in this study, carried out at approximately ambient pressure, were the following (on a dry basis): NO = 400 ppm, H{sub 2} = 40000-20,000 ppm (0.4--2 vol%), O{sub 2} = 5 vol%, CO{sub 2} = 13 vol%, and N{sub 2} = balance. When water was added to the reactant mixture, it was added so that H{sub 2}O = 8 vol%. The total gas flow, expressed as gas hourly space velocity (GHSV), was 10,000 hr{sup {minus}1}, unless specified otherwise. Comparison tests were carried out using NH{sub 3} = 400 ppm in place of the H{sub 2}. Each of the gases was fed into the reactor gas manifold and controlled by a separate flow meter. The NO, H{sub 2} and NH{sub 3} components were utilized as mixtures in N{sub 2}, while CO{sub 2}, and O{sub 2} were added as pure gases. When experiments were carried out in the presence of sulfur dioxide, the SO{sub 2} was added via a SO{sub 2}/N{sub 2} gas mixture to achieve the desired SO{sub 2} concentration in the reactant gas mixture. In the exit stream, NO and N{sub 2}O were determined by an infrared analyzer.

  15. Low-temperature selective catalytic reduction of NO with propylene in excess oxygen over the Pt/ZSM-5 catalyst.

    Science.gov (United States)

    Zhang, Zhixiang; Chen, Mingxia; Jiang, Zhi; Shangguan, Wenfeng

    2011-10-15

    A 0.5 wt% Pt/ZSM-5 catalyst was used for the low-temperature selective catalytic reduction (SCR) of NO with C(3)H(6) in the presence of excess oxygen. Under an atmosphere of 150 ppm NO, 150 ppm C(3)H(6) and 18 vol% O(2) (GHSV 72,000 h(-1)), Pt/ZSM-5 showed remarkably high catalytic performance giving 77.1% NO reduction to N(2) + N(2)O and 79.7% C(3)H(6) conversion to CO(2) simultaneously at 140 °C. The samples were characterized by means of NO temperature programmed desorption (TPD), NO/C(3)H(6) temperature programmed oxidation (TPO), BET surface area, XRD and TEM. The catalytic activities of C(3)H(6) combustion and NO oxidation are improved by well-dispersed platinum significantly. It is found that the enhanced activity of Pt/ZSM-5 for the low-temperature SCR is associated with its outstanding activities in the TPO processes of NO to NO(2) and C(3)H(6) to CO(2) in low temperature range.

  16. MOF-74 as an Efficient Catalyst for the Low-Temperature Selective Catalytic Reduction of NOx with NH3.

    Science.gov (United States)

    Jiang, Haoxi; Wang, Qianyun; Wang, Huiqin; Chen, Yifei; Zhang, Minhua

    2016-10-12

    In this work, Mn-MOF-74 with hollow spherical structure and Co-MOF-74 with petal-like shape have been prepared successfully via the hydrothermal method. The catalysts were characterized using X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), thermogravimetry-mass spectrum analysis (TG-MS), N2 adsorption/desorption, scanning electron microscopy (SEM), and X-ray photoelectron spectroscopy (XPS). It is found that MOF-74(Mn, Co) exhibits the capability for selective catalytic reduction (SCR) of NOx at low temperatures. Both experimental (temperature-programmed desorption, TPD) and computational methods have shown that Co-MOF-74 and Mn-MOF-74 owned high adsorption and activation abilities for NO and NH3. The catalytic activities of Mn-MOF-74 and Co-MOF-74 for low-temperature denitrification (deNOx) in the presence of NH3 were 99% at 220 °C and 70% at 210 °C, respectively. It is found that the coordinatively unsaturated metal sites (CUSs) in M-MOF-74 (M = Mn and Co) played important roles in SCR reaction. M-MOF-74 (M = Mn and Co), especially Mn-MOF-74, showed excellent catalytic performance for low-temperature SCR. In addition, in the reaction process, NO conversion on Mn-MOF-74 decreased with the introduction of H2O and SO2 and almost recovered when gas was cut off. However, for Co-MOF-74, SO2 almost has no effect on the catalytic activity. This work showed that MOF-74 could be used prospectively as deNOx catalyst.

  17. Selective catalytic reduction of NO and NO{sub 2} at low temperatures

    Energy Technology Data Exchange (ETDEWEB)

    Koebel, M.; Madia, G.; Elsener, M.

    2001-03-01

    A feed gas containing both NO and NO{sub 2} can react with NH{sub 3} according to two different reaction pathways at low temperatures: The fast SCR reaction has a positive and the ammonium nitrate reaction has a negative temperature coefficient. The deposition of ammonium nitrate in the pores of the catalyst may lead to its temporary deactivation. (author)

  18. Low Temperature Selective Catalytic Reduction of Nitrogen Oxides in Production of Nitric Acid by the Use of Liquid

    Directory of Open Access Journals (Sweden)

    Kabljanac, Ž.

    2011-11-01

    Full Text Available This paper presents the application of low-temperature selective catalytic reduction of nitrous oxides in the tail gas of the dual-pressure process of nitric acid production. The process of selective catalytic reduction is carried out using the TiO2/WO3 heterogeneous catalyst applied on a ceramic honeycomb structure with a high geometric surface area per volume. The process design parameters for nitric acid production by the dual-pressure procedure in a capacity range from 75 to 100 % in comparison with designed capacity for one production line is shown in the Table 1. Shown is the effectiveness of selective catalytic reduction in the temperature range of the tail gas from 180 to 230 °C with direct application of liquid ammonia, without prior evaporation to gaseous state. The results of inlet and outlet concentrations of nitrous oxides in the tail gas of the nitric acid production process are shown in Figures 1 and 2. Figure 3 shows the temperature dependence of the selective catalytic reduction of nitrous oxides expressed as NO2in the tail gas of nitric acid production with the application of a constant mass flow of liquid ammonia of 13,0 kg h-1 and average inlet mass concentration of the nitrous oxides expressed as NO2of 800,0 mgm-3 during 100 % production capacity. The specially designed liquid-ammonia direct-dosing system along with the effective homogenization of the tail gas resulted in emission levels of nitrous oxides expressed as NO2 in tail gas ranging from 100,0 to 185,0 mg m-3. The applied low-temperature selective catalytic reduction of the nitrous oxides in the tail gases by direct use of liquid ammonia is shown in Figure 4. It is shown that low-temperature selective catalytic reduction with direct application of liquid ammonia opens a new opportunity in the reduction of nitrous oxide emissions during nitric acid production without the risk of dangerous ammonium nitrate occurring in the process of subsequent energy utilization of

  19. [Nano-MnO(x) catalyst for the selective catalytic reduction of NO by NH3 in low-temperature].

    Science.gov (United States)

    Tang, Xiao-Long; Hao, Ji-Ming; Xu, Wen-Guo; Li, Jun-Hua

    2007-02-01

    Nanometer particles composed of manganese oxides (Nano-MnO(x)), which prepared by rheological phase reaction method, show superior low-temperature SCR activity for NO with NH3 in the presence of excess O2. In experiments, the NO conversion is 98.25% at 80 degrees C, and nearly 100% NO could be converted in 100 - 150 degrees C. Due to the reason of competing adsorption, H2O has a slight impact on the activity and the deactivation of SO2 is reversible. The experiments implied that the superior low-temperature catalytic activity of Nano-MnO(x) was mainly due to its high BET specific areas and poor crystallinity.

  20. Investigation of products of low-temperature catalytic hydrogenization of Donbas coals

    Energy Technology Data Exchange (ETDEWEB)

    Osipov, A.M.; Osipov, K.D.; Chernyshova, M.I.; Petrik, G.K.

    1980-11-01

    The relationship of the composition and properties of primary products of low-temperature hydrogenation is presented in relation to the nature of the coal, of catalysts, and of the conditions of hydrogenation. Temperature, the nature of the catalysts and of the type of coal used were directly related to the content of methane, ethane, propane, and CO/sub 2/, and of hydrogen sulphide in the case of brown gaseous coals, as well as the dissolving of hydrogenates and asphaltene content. The structural composition of components dissolved in methylene chloride was determined by proton magnetic resonance. Results of the experiments indicated that lead chloride was the most promising catalyst for low-temperature hydrogenation.

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

    Science.gov (United States)

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

    2009-10-15

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

  2. Low temperature decomposition of styrene-butadiene rubber and used tire

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Won Il; Hong, In Kwon [Department of Chemical Engineering, Dankook University, Seoul (Korea); Kim, Hyung Jin [Department of Environmental and Civil Engineering, Kimpo College, Kimpo (Korea)

    2000-04-01

    The disposal of automotive tires is an increasing environmental and economic problem but few methods have been proposed to tackle the problematic wastes in a systematic and efficient way. Therefore there is a demand for new recycling systems for automotive tires. Tire and raw material of tire i.e., SBR were degraded using supercritical fluid (SCF) process that is the low temperature degradation process relative to the convectional thermal degradation process. The oil yield was increased and that of char was decreased with the increased reaction temperature and pressure in SCF process. Byt the effect of temperature was larger than those of pressure. The oil yields of tire were 33.8-59.2% and 49.1-72.8% using THF and benzene respectively. So, benzene was suitable solvent in SCF process. The number average molecular weights of SBR and tire were decreased with the increased reaction time and temperature. The oil components were mostly 20 aromatic compounds. The optimum condition of SCF process was 320 degree C, 4000 psi in the case of benzene as a supercritical fluid. 16 refs., 9 figs., 2 tabs.

  3. Synthesis of nanocrystalline ceria thin films by low-temperature thermal decomposition of Ce-propionate

    Energy Technology Data Exchange (ETDEWEB)

    Roura, P., E-mail: pere.roura@udg.es [GRMT, Dept. of Physics, University of Girona, Campus Montilivi, Edif. PII, E17071 Girona, Catalonia (Spain); Farjas, J. [GRMT, Dept. of Physics, University of Girona, Campus Montilivi, Edif. PII, E17071 Girona, Catalonia (Spain); Ricart, S.; Aklalouch, M.; Guzman, R. [Institut de Ciencia de Materials de Barcelona (CSIC), Campus de la UAB, 08193 Bellaterra, Catalonia (Spain); Arbiol, J. [Institut de Ciencia de Materials de Barcelona (CSIC), Campus de la UAB, 08193 Bellaterra, Catalonia (Spain); Institucio Catalana de Recerca i Estudis Avancats (ICREA), Barcelona, Catalonia (Spain); Puig, T.; Calleja, A.; Pena-Rodriguez, O.; Garriga, M.; Obradors, X. [Institut de Ciencia de Materials de Barcelona (CSIC), Campus de la UAB, 08193 Bellaterra, Catalonia (Spain)

    2012-01-01

    Thin films of Ce-propionate (thickness below 20 nm) have been deposited by spin coating and pyrolysed into ceria at temperatures below 200 Degree-Sign C. After 1 h of thermal treatment, no signature of the vibrational modes of Ce-propionate is detected by infrared spectroscopy, indicating that decomposition has been completed. The resulting ceria films are nanocrystalline as revealed by X-ray diffraction (average grain size of 2-2.5 nm) and confirmed by microscopy. They are transparent in the visible region and show the characteristic band gap absorption below 400 nm. A direct band gap energy of 3.50 {+-} 0.05 eV has been deduced irrespective of the pyrolysis temperature (160, 180 and 200 Degree-Sign C).

  4. Catalytic coatings on steel for low-temperature propane prereforming to solid oxide fuel cell (SOFC) application.

    Science.gov (United States)

    Alphonse, Pierre; Ansart, Florence

    2009-08-15

    Catalyst layers (4-20 microm) of rhodium (1 wt%) supported on alumina, titania, and ceria-zirconia (Ce(0.5)Zr(0.5)O(2)) were coated on stainless-steel corrugated sheets by dip-coating in very stable colloidal dispersions of nanoparticles in water. Catalytic performances were studied for low-temperature (catalyst. For all catalysts a first-order kinetics was found with respect to propane at 500 degrees C. Addition of PEG 2000 in titania and ceria-zirconia sols eliminated the film cracking observed without additive with these supports. Besides, the PEG addition strongly expanded the porosity of the layers, so that full catalytic efficiency was maintained when the thickness of the ceria-zirconia and titania films was increased.

  5. Few layer graphene synthesis via SiC decomposition at low temperature and low vacuum

    Science.gov (United States)

    Kayali, Emre; Mercan, Elif; Emre Oren, Ersin; Cambaz Buke, Goknur

    2016-04-01

    Based on the large-scale availability and good electrical properties, the epitaxial graphene (EG) on SiC exhibits a big potential for future electronic devices. However, it is still necessary to work continuously on lowering the formation temperature and vacuum values of EG while improving the quality and increasing the lateral size to fabricate high-performance electronic devices at reduced processing costs. In this study, we investigated the effect of the presence of Mo plate and hydrogen atmosphere as well as the vacuum annealing durations on SiC decomposition. Our studies showed that the graphene layers can be produced at lower annealing temperatures (1200 °C) and vacuum values (10-4 Torr) in the presence of Mo plate and hydrogen. For high quality continuous graphene formation, Mo plate should be in contact with SiC. If there is a gap between Mo and SiC, non-wetting oxide droplets on few layer graphene (FLG) are recorded. Moreover, it is found that the morphology of these islands can be controlled by changing the annealing time and atmosphere conditions, and applying external disturbances such as vibration.

  6. Trends in catalytic NO decomposition over transition metal surfaces

    DEFF Research Database (Denmark)

    Falsig, Hanne; Bligaard, Thomas; Rass-Hansen, Jeppe

    2007-01-01

    The formation of NOx from combustion of fossil and renewable fuels continues to be a dominant environmental issue. We take one step towards rationalizing trends in catalytic activity of transition metal catalysts for NO decomposition by combining microkinetic modelling with density functional...... theory calculations. We show specifically why the key problem in using transition metal surfaces to catalyze direct NO decomposition is their significant relative overbinding of atomic oxygen compared to atomic nitrogen....

  7. Low-Temperature Selective Catalytic Reduction of NO with NH₃ over Mn₂O₃-Doped Fe₂O₃ Hexagonal Microsheets.

    Science.gov (United States)

    Li, Yi; Wan, Yuan; Li, Yanping; Zhan, Sihui; Guan, Qingxin; Tian, Yang

    2016-03-02

    Mn2O3-doped Fe2O3 hexagonal microsheets were prepared for the low-temperature selective catalytic reduction (SCR) of NO with NH3. These hexagonal microsheets were characterized by SEM, TEM, XRD, BET, XPS, NH3-TPD, H2-TPR, and in situ DRIFT and were shown to exhibit a considerable uniform hexagonal microsheet structure and excellent low temperature SCR efficiency. When doped with different Mn molar ratios, Mn2O3 was detected in the Fe2O3 hexagonal microsheets based on the XRD results without the presence of other MnOX species. In addition, the hexagonal microsheets with a Mn/Fe molar ratio of 0.2 showed the best SCR removal performance among the materials, where a 98% NO conversion ratio at 200 °C at a space velocity of 30,000 h(-1) was obtained. Meanwhile, excellent tolerances to H2O and SO2, as well as high thermal stability, were obtained in Mn2O3-doped Fe2O3 hexagonal microsheets. Moreover, on the basis of the XPS and in situ DRIFT results, it can be suggested that coupled Mn2O3 nanocrystals played a key role at low temperatures and produced a possible redox reaction mechanism in the SCR process.

  8. Voronoi-Tessellated Graphite Produced by Low-Temperature Catalytic Graphitization from Renewable Resources.

    Science.gov (United States)

    Zhao, Leyi; Zhao, Xiuyun; Burke, Luke T; Bennett, J Craig; Dunlap, Richard A; Obrovac, Mark N

    2017-09-11

    A highly crystalline graphite powder was prepared from the low temperature (800-1000 °C) graphitization of renewable hard carbon precursors using a magnesium catalyst. The resulting graphite particles are composed of Voronoi-tessellated regions comprising irregular sheets; each Voronoi-tessellated region having a small "seed" particle located near their centroid on the surface. This suggests nucleated outward growth of graphitic carbon, which has not been previously observed. Each seed particle consists of a spheroidal graphite shell on the inside of which hexagonal graphite platelets are perpendicularly affixed. This results in a unique high surface area graphite with a high degree of graphitization that is made with renewable feedstocks at temperatures far below that conventionally used for artificial graphites. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

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

    OpenAIRE

    TsungYu Lee; Hsunling Bai

    2016-01-01

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

  10. Co-Fe-Si Aerogel Catalytic Honeycombs for Low Temperature Ethanol Steam Reforming

    Directory of Open Access Journals (Sweden)

    Montserrat Domínguez

    2012-09-01

    Full Text Available Cobalt talc doped with iron (Fe/Co~0.1 and dispersed in SiO2 aerogel was prepared from silica alcogel impregnated with metal nitrates by supercritical drying. Catalytic honeycombs were prepared following the same procedure, with the alcogel synthesized directly over cordierite honeycomb pieces. The composite aerogel catalyst was characterized by X-ray diffraction, scanning electron microscopy, focus ion beam, specific surface area and X-ray photoelectron spectroscopy. The catalytic layer is about 8 µm thick and adheres well to the cordierite support. It is constituted of talc layers of about 1.5 µm × 300 nm × 50 nm which are well dispersed and anchored in a SiO2 aerogel matrix with excellent mass-transfer properties. The catalyst was tested in the ethanol steam reforming reaction, aimed at producing hydrogen for on-board, on-demand applications at moderate temperature (573–673 K and pressure (1–7 bar. Compared to non-promoted cobalt talc, the catalyst doped with iron produces less methane as byproduct, which can only be reformed at high temperature, thereby resulting in higher hydrogen yields. At 673 K and 2 bar, 1.04 NLH2·mLEtOH(l−1·min−1 are obtained at S/C = 3 and W/F = 390 g·min·molEtOH−1.

  11. Low-temperature catalytic oxidation of aldehyde mixtures using wood fly ash: kinetics, mechanism, and effect of ozone.

    Science.gov (United States)

    Kolar, Praveen; Kastner, James R

    2010-02-01

    Poultry rendering emissions contain volatile organic compounds (VOCs) that are nuisance, odorous, and smog and particulate matter precursors. Present treatment options, such as wet scrubbers, do not eliminate a significant fraction of the VOCs emitted including, 2-methylbutanal (2-MB), 3-methylbutanal, and hexanal. This research investigated the low-temperature (25-160 degrees C) catalytic oxidation of 2-MB and hexanal vapors in a differential, plug flow reactor using wood fly ash (WFA) as a catalyst and oxygen and ozone as oxidants. The oxidation rates of 2-MB and hexanal ranged between 3.0 and 3.5 x 10(-9)mol g(-1)s(-1) at 25 degrees C and the activation energies were 2.2 and 1.9 kcal mol(-1), respectively. The catalytic activity of WFA was comparable to other commercially available metal and metal oxide catalysts. We theorize that WFA catalyzed a free radical reaction in which 2-butanone and CO(2) were formed as end products of 2-MB oxidation, while CO(2), pentanal, and butanal were formed as end products of hexanal oxidation. When tested as a binary mixture at 25 and 160 degrees C, no inhibition was observed. Additionally, when ozone was tested as an oxidant at 160 degrees C, 100% removal was achieved within a 2-s reaction time. These results may be used to design catalytic oxidation processes for VOC removal at poultry rendering facilities and potentially replace energy and water intensive air pollution treatment technologies currently in use.

  12. [Chemical structure of bioethanol lignin by low-temperature alkaline catalytic hydrothermal treatment].

    Science.gov (United States)

    Liu, Xiao-Huan; Zhang, Ming-Ming; Wang, Ji-Fu; Xu, Yu-Zhi; Wang, Chun-Peng; Chu, Fu-Xiang

    2013-11-01

    In order to improve the reaction activity of bioethanol lignin, we investigated the activation of bioethanol lignin by a hydrothermal treatment method. Catalytic hydrothermal treatment of bioethanol lignin was performed at 180 degrees C for 3 h in the presence of alkaline solutions (NaOH, Na2 CO3, KOH and K2 CO3), the change in bioethanol lignin structures was studied comparatively by FTIR, 1H NMR,GPC and elemental analysis. FTIR spectra showed that after alkali hydrothermal treatment, the band at 1 375 cm(-1) attributed to the phenolic hydroxyl groups increased, and the band intensity at 1 116 cm(-1) attributed to the ether bond decreased. On the other hand, the band at 1 597 and 1 511 cm(-1) attributed to aromatic skeletal vibration remained almost unchanged. 1H NMR spectra showed that after alkali hydrothermal treatment, the number of aromatic methoxyl is increased, and based on the increment of the content of phenolic hydroxyl, the catalytic activity can be ranked as follows: KOH > NaOH > K2 CO3 > Na2 CO3. Especially for KOH, the increment of the content of phenolic hydroxyl was 170%, because the ion radius of potassium cation is bigger than sodium cation, so the potassium cations more easily formed cation adducts with lignin. GPC results showed that the molecular weight of alkali hydrothermal treatment lignin decreased and the molecular distribution got wider. Elemental analysis showed that hydrothermal treatment could break the interlinkage between lignin and protein, which can reduce the protein content and increase the purity of lignin, meanwhile, the content of O and H both decreased,while C fell, indicating that the bioethanol lignin had suffered a decarbonylation reaction. This is the most benefit of the lignin as a substitute for phenol.

  13. Development of Catalytic Tar Decomposition in an Internally Circulating Fluidized-Bed Gasifier

    Science.gov (United States)

    Xiao, Xianbin; Le, Due Dung; Morishita, Kayoko; Li, Liuyun; Takarada, Takayuki

    Biomass gasification in an Internally Circulating Fluidized-bed Gasifier (ICFG) using Ni/Ah03 as tar cracking catalyst is studied at low temperature. Reaction conditions of the catalyst bed are discussed, including catalytic temperature and steam ratio. High energy efficiency and hydrogen-rich, low-tar product gas can be achieved in a properly designed multi-stage gasification process, together with high-performance catalyst. In addition, considering the economical feasibility, a newly-developed Ni-loaded brown coal char is developed and evaluated as catalyst in a lab-scale fluidized bed gasifier with catalyst fixed bed. The new catalyst shows a good ability and a hopeful prospect oftar decomposition, gas quality improvement and catalytic stability.

  14. Selective catalytic reduction of NO and NO{sub 2} at low temperatures

    Energy Technology Data Exchange (ETDEWEB)

    Koebel, Manfred; Madia, Giuseppe; Elsener, Martin [Paul Scherrer Institute, CH-5232 PSI Villigen (Switzerland)

    2002-04-15

    The fast SCR reaction using equimolar amounts of NO and NO{sub 2} is a powerful means to enhance the NO{sub x} conversion over a given SCR catalyst. NO{sub 2} fractions in excess of 50% of total NO{sub x} should be avoided because the reaction with NO{sub 2} only is slower than the standard SCR reaction. At temperatures below 200C, due to its negative temperature coefficient, the ammonium nitrate reaction gets increasingly important. Half of each NH{sub 3} and NO{sub 2} react to form dinitrogen and water in analogy to a typical SCR reaction. The other half of NH{sub 3} and NO{sub 2} form ammonium nitrate in close analogy to a NO{sub x} storage-reduction catalyst. Ammonium nitrate tends to deposit in solid or liquid form in the pores of the catalyst and this will lead to its temporary deactivation.The various reactions have been studied experimentally in the temperature range 150-450C for various NO{sub 2}/NO{sub x} ratios. The fate of the deposited ammonium nitrate during a later reheating of the catalyst has also been investigated. In the absence of NO, the thermal decomposition yields mainly ammonia and nitric acid. If NO is present, its reaction with nitric acid on the catalyst will cause the formation of NO{sub 2}.

  15. Low-temperature selective catalytic reduction of NO on MnO(x)/TiO(2) prepared by different methods.

    Science.gov (United States)

    Jiang, Boqiong; Liu, Yue; Wu, Zhongbiao

    2009-03-15

    Catalysts based on MnO(x)/TiO(2) were prepared by sol-gel, impregnation, and coprecipitation methods for low-temperature selective catalytic reduction (SCR) of NO with NH(3). Among the catalysts, the sample prepared by sol-gel method had the best performance on both activity and SO(2) resistance. From the results of thermo gravimetric analysis (TGA), X-ray diffraction (XRD), transmission electron microscopy (TEM) and X-ray photoelectron spectrum (XPS), it was known that manganese oxides and titania existed in different phase in the samples prepared by three methods. Strong interaction, large surface area, high concentration of hydroxyl groups, high concentration of amorphous Mn on the surface might be the main reasons for the excellent performance of the catalysts.

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

    Science.gov (United States)

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

    2016-11-01

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

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

    Directory of Open Access Journals (Sweden)

    Tomohiro Iwasaki

    2016-06-01

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

  18. Performance of selective catalytic reduction of NO with NH3 over natural manganese ore catalysts at low temperature.

    Science.gov (United States)

    Wang, Tao; Zhu, Chengzhu; Liu, Haibo; Xu, Yongpeng; Zou, Xuehua; Xu, Bin; Chen, Tianhu

    2017-03-16

    Natural manganese ore catalysts for selective catalytic reduction (SCR) of NO with NH3 at low temperature in the presence and absence of SO2 and H2O were systematically investigated. The physical and chemical properties of catalysts were characterized by X-ray diffraction, Brunauer-Emmett-Teller (BET) specific surface area, NH3 temperature-programmed desorption (NH3-TPD) and NO-TPD methods. The results showed that natural manganese ore from Qingyang of Anhui Province had a good low-temperature activity and N2 selectivity, and it could be a novel catalyst in terms of stability, good efficiency, good reusability and lower cost. The NO conversion exceeded 85% between 150°C and 300°C when the initial NO concentration was 1000 ppm. The activity was suppressed by adding H2O (10%) or SO2 (100 or 200 ppm), respectively, and its activity could recover while the SO2 supply is cut off. The simultaneous addition of H2O and SO2 led to the increase of about 100% in SCR activity than bare addition of SO2. The formation of the amorphous MnOx, high concentration of lattice oxygen and surface-adsorbed oxygen groups and a lot of reducible species as well as adsorption of the reactants brought about excellent SCR performance and exhibited good SO2 and H2O resistance.

  19. SSZ-13-supported manganese oxide catalysts for low temperature selective catalytic reduction of NOx by NH3

    Indian Academy of Sciences (India)

    YONGZHOU YE; FEI SHEN; HONGNING WANG; RUOYU CHEN

    2017-06-01

    A series of Mn/SSZ-13 catalysts of varying Mn content were synthesized by hydrothermal and co-precipitation methods. Their performances for the selective catalytic reduction (SCR) of NOx with NH₃ were evaluated. The results indicate that over 95% NOx conversion was achieved at a low temperature of 150◦C with an Mn loading of 4.74 wt%. Meanwhile, the NOx conversion rate remained greater than 90% at 450◦C. The Mn/SSZ-13 catalysts were characterized by X-ray diffraction, ultraviolet–visible diffuse reflectance spectroscopy, Raman spectroscopy, transmission electronmicroscopy,N₂-adsorption, temperature-programmed desorption, and X-ray photoelectron spectroscopy. The analysis indicates that Mn₂O₃, Mn₃O₄, and amorphous MnO₂ coexist on the surface of the Mn/SSZ-13 catalysts, with MnO₂ comprising the largest proportion, which may contribute to the high SCR activity. Additionally, the specific surface area and pore volume both decreasewith increasing Mn loading. The Mn/SSZ-13 catalyst with 4.74 wt% of Mn has a high concentration of lattice oxygen, a high amorphous MnO₂ content, and greatest number of strong Lewis acid sites, which are beneficial to the adsorption of NH₃, and may account for its superior catalytic activity.

  20. KINETIC ANALYSIS OF THE CATALYTIC DECOMPOSITION OF HYDRAZINE

    Directory of Open Access Journals (Sweden)

    J.E. de MEDEIROS

    1998-06-01

    Full Text Available The bond-order conservation method was used to study the catalytic decomposition of N2H4. Variation in the activation energy, E, of the most relevant steps was calculated as a function of the enthalpy of adsorption of N, QN, between 0 and 1250 kJmol-1. Results suggest that below QN = 520 kJmol-1 the catalytic decomposition of N2H4 produces mostly N2 and H2. Above QN = 520 kJmol-1, NH3 and N2 are the main products. Near QN = 520 kJmol-1 N2, H2 and NH3 are obtained, in agreement with experimental results on different metals.

  1. Thermodynamics behind carbon nanotube growth via endothermic catalytic decomposition reaction.

    Science.gov (United States)

    Harutyunyan, Avetik R; Kuznetsov, Oleg A; Brooks, Christopher J; Mora, Elena; Chen, Gugang

    2009-02-24

    Carbon filaments can be grown using hydrocarbons with either exothermic or endothermic catalytic decomposition enthalpies. By in situ monitoring the evolution of the reaction enthalpy during nanotube synthesis via methane gas, we found that although the decomposition reaction of methane is endothermic an exothermic process is superimposed which accompanies the nanotube growth. Analysis shows that the main contributor in this liberated heat is the radiative heat transfer from the surroundings, along with dehydrogenation reaction of in situ formed secondary hydrocarbons on the catalyst surface and the carbon hydrogenation/oxidation processes. This finding implies that nanotube growth process enthalpy is exothermic, and particularly, it extends the commonly accepted temperature gradient driven growth mechanism to the growth via hydrocarbons with endothermic decomposition enthalpy.

  2. Effect of fluoride doping for catalytic ozonation of low-temperature denitrification over cerium–titanium catalysts

    Energy Technology Data Exchange (ETDEWEB)

    Ding, Jie [School of Chemical Engineering, Nanjing University of Science and Technology, Nanjing, Jiangsu 210094 (China); Department of Chemical and Petroleum Engineering, University of Wyoming, Laramie, WY 82071 (United States); Nanjing AIREP Environmental Protection Technology Co., Ltd., Nanjing, Jiangsu 210091 (China); Lin, Jiandong; Xiao, Junjun; Zhang, Yi [School of Chemical Engineering, Nanjing University of Science and Technology, Nanjing, Jiangsu 210094 (China); Zhong, Qin, E-mail: zq304@mail.njust.edu.cn [School of Chemical Engineering, Nanjing University of Science and Technology, Nanjing, Jiangsu 210094 (China); Nanjing AIREP Environmental Protection Technology Co., Ltd., Nanjing, Jiangsu 210091 (China); Zhang, Shule; Guo, Lina [School of Chemical Engineering, Nanjing University of Science and Technology, Nanjing, Jiangsu 210094 (China); Nanjing AIREP Environmental Protection Technology Co., Ltd., Nanjing, Jiangsu 210091 (China); Fan, Maohong [Department of Chemical and Petroleum Engineering, University of Wyoming, Laramie, WY 82071 (United States)

    2016-04-25

    Nanostructure cerium–titanium catalysts including fluoride (F{sup −}) doped ones were prepared by impregnation (Ce/TiO{sub 2} and Ce/F–TiO{sub 2}) and co-precipitation (CeTi and CeTiF) method, and tested as ozonation catalysts for low-temperature NO{sub X} removal ranging from 40 to 180 °C. Interestingly, the doping of F{sup −} promotes the NO{sub X} removal for CeTi whereas inhibits the removal for Ce/TiO{sub 2}. The NO{sub X} removal presents linear relationship with the concentration of hydroxyl radicals (·OH). The surface –OH linked to Ce atoms as well as the H{sub 2}O adsorption over Ce atoms play the important role in the generation of ·OH radicals. The doping of F{sup −} into CeTi improves the activation of Ce–OH linkage bonds and the adsorption of H{sub 2}O over Ce atoms, thus increasing the concentration of ·OH radicals and catalytic activities. Although the doping of F{sup −} into Ce/TiO{sub 2} enhances the density of surface –OH, the ones linked to Ce atoms remain constant and the H{sub 2}O adsorption over Ce atoms are declined, finally declining the catalytic activities. - Highlights: • The NO{sub X} removal is determined by the concentration of ·OH radicals. • The surface –OH linked to Ce atoms plays an important role. • The adsorption of H{sub 2}O over Ce atoms is critical.

  3. [Low-temperature catalytic reduction of NO over Fe-MnOx-CeO2/ZrO2 catalyst].

    Science.gov (United States)

    Liu, Rong; Yang, Zhi-Qin

    2012-06-01

    Fe-MnOx-CeO2/ZrO2 catalysts were prepared through impregnation method with nanometer ZrO2 as a carrier and used in selective catalytic reduction of NO with NH3 at low temperature. Effects of active component ratio and loading of promoter on the catalyst activity were investigated. The catalysts were characterized by means of XRD, SEM, EDS and BET. The effects of temperature, SO2 and H2O on NO conversion were studied and the results showed that in the absence of SO2 and H2O, the catalyst of 8% Fe-10% MnOx-CeO2/ZrO2 had good activity and stability as well as the NOx removal efficiency reached 85.23% at 120 degrees C and 92.0% at 180 degrees C. The presence of SO2 and H2O results in the catalyst deactivated. Properties of the catalyst on different reaction stages were characterized by FT-IR to study the inactivation mechanism of the catalyst. The results showed that the catalyst deactivation was due to the deposition of ammonium sulfate on the catalyst and the sulphation of the catalyst.

  4. Mn-CeOx/Ti-PILCs for selective catalytic reduction of NO with NH3 at low temperature.

    Science.gov (United States)

    Shen, Boxiong; Ma, Hongqing; Yao, Yan

    2012-01-01

    Titanium-pillared clays (Ti-PILCs) were obtained by different ways from TiCl4, Ti(OC3H7)4 and TiOSO4, respectively. Mn-CeO(x)/)Ti-PILCs were then prepared and their activities of selective catalytic reduction (SCR) of NO with NH3 at low-temperature were evaluated. Mn-CeO(x)/Ti-PILCs were characterized by X-ray diffraction, N2 adsorption, Fourier transform infrared spectroscopy, thermal analysis, temperature-programmed desorption of ammonia and H2-temperature-programmed reduction. It was found that Ti-pillar tend to be helpful for the enlargement of surface area, pore volume, acidity and the enhancement of thermal stability for Mn-CeO(x)/Ti-PILCs. Mn-CeO(x)/Ti-PILCs catalysts were active for the SCR of NO. Among three resultant Mn-CeO(x)/Ti-PILCs, the catalyst from TiOSO4 showed the highest activity with 98% NO conversion at 220 degrees C, it also exhibited good resistance to H2O and SO2 in flue gas. The catalyst from TiCl4 exhibited the lowest activity due to the unsuccessful pillaring process.

  5. Simultaneous removal of NO x and SO2 by low-temperature selective catalytic reduction over modified activated carbon catalysts

    Science.gov (United States)

    Liu, Ye; Ning, Ping; Li, Kai; Tang, Lihong; Hao, Jiming; Song, Xin; Zhang, Guijian; Wang, Chi

    2017-03-01

    A series of modified porous activated carbon (AC) catalysts prepared by impregnation were investigated for the low-temperature (≤250°C) selective catalytic reduction (SCR) of NO x with NH3 with simultaneous removal of SO2. The effects of various preparation conditions and reaction conditions on NO and SO2 conversions were observed, such as support type, active components, copper loading, calcination temperature and presence of H2O and O2. The modified AC catalysts were characterized by BET, XRD, TG and TPX methods. The activity test results showed that the optimal catalyst is 15% Cu/WCSAC which can provide 52% NO conversion and 68% SO2 conversion simultaneously at 175°C with a space velocity of 30000 h‒1, and the optimal calcination temperature was 500°C. The presence of H2O could inhibit NO conversion and promote the SO2 conversion. The effect of O2 (0-5%) was evaluated, and the NO and SO2 conversions were best when the concentration of O2 was 3%. Research demonstrated that Cu/WCSAC catalyst was a kind of potential catalysts due to the amorphous phase, high specific areas and high active ability.

  6. Catalytic Methane Decomposition over Fe-Al2O3

    KAUST Repository

    Zhou, Lu

    2016-05-09

    The presence of a Fe-FeAl2O4 structure over an Fe-Al2O3 catalysts is demonstrated to be vital for the catalytic methane decomposition (CMD) activity. After H2 reduction at 750°C, Fe-Al2O3 prepared by means of a fusion method, containing 86.5wt% FeAl2O4 and 13.5wt% Fe0, showed a stable CMD activity at 750°C for as long as 10h. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

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

    Science.gov (United States)

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

    2007-08-15

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

  8. Bauxite-supported Transition Metal Oxides: Promising Low-temperature and SO2-tolerant Catalysts for Selective Catalytic Reduction of NOx

    OpenAIRE

    Xiuyun Wang; Wen Wu; Zhilin Chen; Ruihu Wang

    2015-01-01

    In order to develop low-temperature (below 200 °C) and SO2-tolerant catalysts for selective catalytic reduction (SCR) of NOx, a series of cheap M/bauxite (M = Mn, Ni and Cu) catalysts were prepared using bauxite as a support. Their SCR performances are much superior to typical V2O5/TiO2, the addition of M into bauxite results in significant promotion of NOx removal efficiency, especially at low temperature. Among the catalysts, Cu/bauxite exhibits wide temperature window over 50–400 °C, stron...

  9. Effect of decomposition and organic residues on resistivity of copper films fabricated via low-temperature sintering of complex particle mixed dispersions.

    Science.gov (United States)

    Yong, Yingqiong; Nguyen, Mai Thanh; Tsukamoto, Hiroki; Matsubara, Masaki; Liao, Ying-Chih; Yonezawa, Tetsu

    2017-03-24

    Mixtures of a copper complex and copper fine particles as copper-based metal-organic decomposition (MOD) dispersions have been demonstrated to be effective for low-temperature sintering of conductive copper film. However, the copper particle size effect on decomposition process of the dispersion during heating and the effect of organic residues on the resistivity have not been studied. In this study, the decomposition process of dispersions containing mixtures of a copper complex and copper particles with various sizes was studied. The effect of organic residues on the resistivity was also studied using thermogravimetric analysis. In addition, the choice of copper salts in the copper complex was also discussed. In this work, a low-resistivity sintered copper film (7 × 10(-6) Ω·m) at a temperature as low as 100 °C was achieved without using any reductive gas.

  10. The characterization and activity of F-doped vanadia/titania for the selective catalytic reduction of NO with NH3 at low temperatures.

    Science.gov (United States)

    Li, Yuntao; Zhong, Qin

    2009-12-30

    A F-doped vanadia/titania catalyst has been developed by partly substituting the lattice oxygen of the catalyst with fluorine, using NH(4)F as a precursor. The aim of this novel design was to promote the activity of a catalyst with low vanadia loading in the low-temperature selective catalytic reduction of NO with NH(3). Analysis by N(2) physisorption, XPS, ICP, XRD, ESR and PL spectra showed that fluorine doping facilitated the formation of V(4+) and Ti(3+) ions mainly by charge compensation, promoted the distribution of vanadium on the catalyst surface, and increased the amount of surface superoxide ions. The catalytic activity of NO removal was promoted by F-doping. And the catalyst with [F]/[Ti]=1.35 x 10(-2) showed the highest NO removal efficiency in SCR reaction at low temperatures.

  11. Effect of MoO3 on vanadium based catalysts for the selective catalytic reduction of NOx with NH3 at low temperature.

    Science.gov (United States)

    Zhu, Lin; Zhong, Zhaoping; Yang, Han; Wang, Chunhua

    2017-06-01

    The selective catalytic reduction (SCR) activities of the MoO3 doped V/WTi catalysts prepared by the incipient wetness impregnation method at low temperature were investigated. The results showed that the addition of MoO3 could enhance the NOx conversion at low temperature and the best SCR activity was obtained when the dosage of MoO3 reached 5wt.%. The NH3-TPD and DRIFTS experiments indicated that the addition of MoO3 changed the type and number of acid sites on the surface of catalysts and reaction activities of acid sites were altered at the same time. The redox capacity and amount of active oxygen species got improved for V3Mo5/WTi catalyst, which could be confirmed by the H2-TPR and transient response experiments. Water vapor inhibited the NOx conversion at low temperature. Deposition of ammonium sulfate or bisulfate might be main reason for the loss of catalytic activity in the presence of SO2 at low temperature. Choosing the suitable NH3/NO ratio and elevation of reaction temperature both could weaken the influence of SO2 on the SCR activity of the V3Mo5/WTi catalyst. Thermal treatment of the deactivated catalyst at 350°C could get the low temperature activity recovered. The decrease of GHSV improved the deNOx efficiency at low temperature and we speculated that the rational technological process and operation parameters could contribute to the application of this kind of catalysts in real industrial environment. Copyright © 2016. Published by Elsevier B.V.

  12. 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.

  13. Demonstration of organic volatile decomposition and bacterial sterilization by miniature dielectric barrier discharges on low-temperature cofired ceramic electrodes

    Science.gov (United States)

    Kim, Duk-jae; Shim, Yeun-keun; Park, Jeongwon; Kim, Hyung-jun; Han, Jeon-geon

    2016-04-01

    Nonthermal atmospheric-pressure plasma discharge is designed with low-temperature cofired ceramic (LTCC) electrodes to achieve dielectric barrier surface discharge (DBSD). The environmental requirement (below 0.05 ppm) of the amount of byproducts (ozone and NO x ) produced during the process was met by optimizing the electrode design to produce a high dielectric barrier discharge for low-voltage (∼700 V) operation and minimizing the distance between electrodes to improve the plasma discharging efficiency. The concentrations of volatile organic compounds (VOCs) within interior cabins of commercial vehicles were significantly reduced after 1-h treatment to improve air quality cost-effectively. This atmospheric-pressure plasma process was demonstrated for the sterilization of Escherichia coli to prevent food poisoning during the preservation of food in refrigerators.

  14. In situ DRIFTS studies on MnOx nanowires supported by activated semi-coke for low temperature selective catalytic reduction of NOx with NH3

    Science.gov (United States)

    Chen, Yan; Zhang, Zuotai; Liu, Lili; Mi, Liang; Wang, Xidong

    2016-03-01

    To mitigate the threat of NOx on the environment, MnOx nanowires were fabricated on activated semi-coke (MnOx NW/ASC) for the first time. The prepared MnOx NW/ASC was used for the low temperature selective catalytic reduction (SCR) of NOx with NH3, which achieved an efficiency of over 90% with a low loading content of 1.64 wt% at 150-210 °C. This high performance could be ascribed to synergistic effect between MnOx and ASC. Specifically, the large specific surface area and reducible property of ASC facilitated the dispersion of MnOx and the formation of Mn3+, respectively. Meanwhile, MnOx nanowires provided more redox sites and lattice oxygen species due to the coexistence of Mn3+ and Mn4+, which accelerated the catalytic cycle. The in situ DRIFTS studies revealed that ASC was conducive to the adsorption of NO and NH3. Most importantly, the existence of Mn3+ favored the formation of amide species and the subsequent reduction reaction. Furthermore, the Langmuir-Hinshelwood (L-H) route between coordinated NH3 and bidentate nitrate was predominating in the SCR process and responsible for the high catalytic activity at low temperature.

  15. Bauxite-supported Transition Metal Oxides: Promising Low-temperature and SO2-tolerant Catalysts for Selective Catalytic Reduction of NOx.

    Science.gov (United States)

    Wang, Xiuyun; Wu, Wen; Chen, Zhilin; Wang, Ruihu

    2015-05-19

    In order to develop low-temperature (below 200 °C) and SO2-tolerant catalysts for selective catalytic reduction (SCR) of NOx, a series of cheap M/bauxite (M = Mn, Ni and Cu) catalysts were prepared using bauxite as a support. Their SCR performances are much superior to typical V2O5/TiO2, the addition of M into bauxite results in significant promotion of NOx removal efficiency, especially at low temperature. Among the catalysts, Cu/bauxite exhibits wide temperature window over 50-400 °C, strong resistance against SO2 and H2O as well as good regeneration ability in SCR of NOx. NOx conversion is more than 80% at 50-200 °C, and N2 selectivity is more than 98%. Cu/bauxite can serve as a promising catalyst in SCR of NOx.

  16. Comparison of titania nanotubes and titanium dioxide as supports of low-temperature selective catalytic reduction catalysts under sulfur dioxide poisoning.

    Science.gov (United States)

    Lee, TsungYu; Liou, Sihyu; Bai, Hsunling

    2017-03-01

    A series of iron-manganese oxide catalysts supported on TiO2 and titanium nanotubes (TNTs) were studied for low temperature selective catalytic reduction (SCR) of NO with NH3 in the presence of SO2. The results showed that the specific surface area and the amount of Brønsted acid sites were highly correlated. The results also demonstrated that higher Mn(4+)/Mn(3+) ratios and larger specific surface areas might be the main reasons for the excellent performance of MnFe-TNTs catalyst after SO2 poisoning. The SO2 poisoning effect could be minimized by reducing the GHSV, increasing the reaction temperature, or increasing the [NH3]/[NO] molar ratio. The results also indicated that the formation of ammonium sulfate had a stronger effect on the NO conversion efficiency as compared to the formation of metal sulfate. Thus operating the low temperature SCR at above 230 (o)C to avoid the formation of ammonium sulfate would be the priority choice when SO2 poisoning is a concerned issue. Implications: Low-temperature selective catalytic reduction (SCR) has attracted increasing attention due to that it can reduce the energy consumption for the SCR process employed in industries such as steel plants and glass manufacturing plants. However, it also suffers from the sulfur dioxide (SO2) poisoning problem. This study investigates the possibility of using titania nanotubes (TNTs) as the support of Mn/Fe bimetal oxide catalysts for low-temperature SCR to reduce the SO2 poisoning. The results indicated that the MnFe-TNT catalyst can tolerate SO2 for a longer time as compared with the MnFe-TiO2 catalyst.

  17. Thermo catalytic decomposition of methane over Pd/AC and Pd/CB catalysts for hydrogen production and carbon nanofibers formation

    Directory of Open Access Journals (Sweden)

    K. Srilatha

    2014-09-01

    Full Text Available Hydrogen production studies have been carried using Thermo Catalytic Decomposition (TCD Unit. Thermo catalytic decomposition of methane is an attractive route for COx free production of hydrogen required in fuel cells. Although metal based catalysts produce hydrogen at low temperatures, carbon formed during methane decomposition reaction rapidly deactivates the catalyst. The present work compares the results of 10 wt% Pd supported on commercially available activated carbon and carbon black catalysts (samples coded as Pd10/AC and Pd10/CB respectively for methane decomposition reaction. Hydrogen has been produced by thermo catalytic decomposition of methane at 1123K and Volume Hourly Space Velocity (VHSV of 1.62 L/h g on the activity of both the catalysts has been studied. XRD of the above catalysts revealed, moderately crystalline peaks of Pd which may be responsible for the increase in catalytic life and formation of carbon fibers. Also during life studies (850°C and 54 sccm of methane it has been observed that the activity of carbon black is sustainable for a longer time compared to that of activated carbon.

  18. Thermal decomposition of expanded polystyrene in a pebble bed reactor to get higher liquid fraction yield at low temperatures.

    Science.gov (United States)

    Chauhan, R S; Gopinath, S; Razdan, P; Delattre, C; Nirmala, G S; Natarajan, R

    2008-11-01

    Expanded polystyrene is one of the polymers produced in large quantities due to its versatile application in different fields. This polymer is one of the most intractable components in municipal solid waste. Disposal of polymeric material by pyrolysis or catalytic cracking yields valuable hydrocarbon fuels or monomers. Literature reports different types of reactors and arrangements that have uniform temperatures during pyrolysis and catalytic cracking. The present study focuses on reducing the temperature to maximize the quantity of styrene monomer in the liquid product. A bench scale reactor has been developed to recover the styrene monomer and other valuable chemicals. Experiments were carried under partial oxidation and vacuum conditions in the temperature range of 300-500 degrees C. In the pyrolysis optimization studies, the best atmospheric condition was determined to be vacuum, the pyrolysis temperature should be 500 degrees C, yield of liquid product obtained was 91.7% and yield of styrene obtained was 85.5%. In the characterization studies, distillation and IR spectroscopy experiments were carried out. The remaining of the liquid product comprises of benzene, ethyl benzene, and styrene dimers and trimers.

  19. Catalytic spectrophotometric determination of iodine in coal by pyrohydrolysis decomposition

    Energy Technology Data Exchange (ETDEWEB)

    Wu Daishe [School of Environmental Science and Engineering, Nanchang University, Nanchang 330031 (China); Institute of Geographic Sciences and Resources Research, CAS, Beijing 100101 (China)], E-mail: dswu@ncu.edu.cn; Deng Haiwen [School of Environmental Science and Engineering, Nanchang University, Nanchang 330031 (China); Wang Wuyi [Institute of Geographic Sciences and Resources Research, CAS, Beijing 100101 (China); Xiao Huayun [School of Environmental Science and Engineering, Nanchang University, Nanchang 330031 (China)

    2007-10-10

    A method for the determination of iodine in coal using pyrohydrolysis for sample decomposition was proposed. A pyrohydrolysis apparatus system was constructed, and the procedure was designed to burn and hydrolyse coal steadily and completely. The parameters of pyrohydrolysis were optimized through the orthogonal experimental design. Iodine in the absorption solution was evaluated by the catalytic spectrophotometric method, and the absorbance at 420 nm was measured by a double-beam UV-visible spectrophotometer. The limit of detection and quantification of the proposed method were 0.09 {mu}g g{sup -1} and 0.29 {mu}g g{sup -1}, respectively. After analysing some Chinese soil reference materials (SRMs), a reasonable agreement was found between the measured values and the certified values. The accuracy of this approach was confirmed by the analysis of eight coals spiked with SRMs with an indexed recovery from 94.97 to 109.56%, whose mean value was 102.58%. Six repeated tests were conducted for eight coal samples, including high sulfur coal and high fluorine coal. A good repeatability was obtained with a relative standard deviation value from 2.88 to 9.52%, averaging 5.87%. With such benefits as simplicity, precision, accuracy and economy, this approach can meet the requirements of the limits of detection and quantification for analysing iodine in coal, and hence it is highly suitable for routine analysis.

  20. Negative catalytic effect of water on the reactivity of hydrogen abstraction from the C-H bond of dimethyl ether by deuterium atoms through tunneling at low temperatures

    Science.gov (United States)

    Oba, Yasuhiro; Watanabe, Naoki; Kouchi, Akira

    2016-10-01

    We report an experimental study on the catalytic effect of solid water on the reactivity of hydrogen abstraction (H-abstraction) from dimethyl ether (DME) in the low-temperature solid DME-H2O complex. When DME reacted with deuterium atoms on a surface at 15-25 K, it was efficiently deuterated via successive tunneling H-abstraction and deuterium (D)-addition reactions. The 'effective' rate constant for DME-H2O + D was found to be about 20 times smaller than that of pure DME + D. This provides the first evidence that the presence of solid water has a negative catalytic effect on tunneling H-abstraction reactions.

  1. Catalytic oxidation of Hg(0) by MnOx-CeO2/γ-Al2O3 catalyst at low temperatures.

    Science.gov (United States)

    Wang, Pengying; Su, Sheng; Xiang, Jun; You, Huawei; Cao, Fan; Sun, Lushi; Hu, Song; Zhang, Yun

    2014-04-01

    MnOx-CeO2/γ-Al2O3 (MnCe) selective catalytic reduction (SCR) catalysts prepared by sol-gel method were employed for low-temperature Hg(0) oxidation on a fixed-bed experimental setup. BET, XRD and XPS were used to characterize the catalysts. MnCe catalysts exhibited high Hg(0) oxidation activity at low temperatures (100-250 °C) under the simulated flue gas (O2, CO2, NO, SO2, HCl, H2O and balanced with N2). Only a small decrease in mercury oxidation was observed in the presence of 1200 ppm SO2, which proved that the addition of Ce helped resist SO2 poisoning. An enhancing effect of NO was observed due to the formation of multi-activity NOx species. The presence of HCl alone had excellent Hg(0) oxidation ability, while 10 ppm HCl plus 5% O2 further increased Hg(0) oxidation efficiency to 100%. Hg(0) oxidation on the MnCe catalyst surface followed the Langmiur-Hinshelwood mechanism, where reactions took place between the adsorbed active species and adsorbed Hg(0) to form Hg(2+). NH3 competed with Hg(0) for active sites on the catalyst surface, hence inhibiting Hg(0) oxidation. This study shows the feasibility of a single-step process integrating low-temperature SCR and Hg(0) oxidation from the coal combustion flue gas.

  2. Low-Temperature Heat Capacity and Thermal Decomposition of Crystalline[Ho(Thr)(H2O)5]Cl3

    Institute of Scientific and Technical Information of China (English)

    蓝孝征; 谭志诚; 刘北平; 南照东; 孙立贤; 徐芬

    2003-01-01

    Rare earth elements have been widely used in many areas. Rare earth complex bearing an amino acid was synthesized to study the influence and the long-term effect of rare earth elements on environment and human beings,because amino acid is the basic unit of the living things. Previous work on these kinds of comidex is focused on synthesis and characterization of them. But thermodynamic data have seldom been reported. Here we present the thermod~nRmle study of [ Ho (Thr)(H20 )5]Cl3. The heat capecity of Holmium complex with threonine,[Ho(Thr)(H2O)5]Cl3,was measured with an automatic adiabatic calorimeter in the temperature range from 79K to 330K and no thermal anomaly was found in this range,Thermodynamic functions relative to standard state 298.15K were derived from the heat capactiy data.Thermal decomposition behavior of the complex in nitrogen atmosphere in the range from 300K to 900K was studied by thermogravimetric(TG) technique and a possible decompostion mechanism was proposed according to the TG-DTG results.

  3. Ce-Mn mixed oxides supported on glass-fiber for low-temperature selective catalytic reduction of NO with NH3

    Institute of Scientific and Technical Information of China (English)

    李乐; 刁永发; 刘鑫

    2014-01-01

    Samples of cerium-manganese oxides supported on modified glass-fiber with different Ce/Mn molar ratios (Ce-Mn/GF) were prepared by an impregnation method and tested for low-temperature (80-180 ºC) selective catalytic reduction (SCR) of NO with ammonia. This brand-new technology could remove NO and particles matter from coal-fired flue gas. The surface properties of the catalysts were examined by means of Brunauer-Emmett-Teller (BET), X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD), and scanning electron microscopy (SEM). The experimental results showed that the catalyst with a Ce/Mn molar ratio of 0.2 obtained high activity of 87.4% NO conversion at 150 ºC under a high space velocity of 50000 h-1. Deactivation poisoned by SO2 still occurred, but the Ce-Mn/GF(0.2) catalyst performed desirable tolerance to SO2 with decreasing 50% in 40 min and then maintaining at about 30% NO conversion. Characterization results indicated that the excellent low-temperature catalytic activity was related to the high specific surface area, pore structure, and amorphous phase.

  4. Low-Temperature Plasma-Catalytic Reduction of Nox by C2H2 in the Presence of Excess Oxygen

    Institute of Scientific and Technical Information of China (English)

    NIU Jinhai; ZHANG Zhihui; LIU Dongping; WANG Qi

    2008-01-01

    Synergistic effects of pulsed DC dielectric barrier discharge (DBD) plasma and In-dium modified HZSM-5 (In/HZSM-5) catalyst for C2H2 selective reduction of Nox at 200℃, in the presence of enriched oxygen by using a one-stage plasma-over-catalyst (POC) reactor, are reported. With a reactant gas mixture of 480 ppm NO, 500 ppm C2H2, 13.0% O2 in N2 and gas hourly space velocity (GHSV) = 10000 h-1, pure catalytic, pure plasma-induced (discharges over fused silica pellets) and plasma-catalytic Nox conversion percentages are 45.0%, 4.0% and 92.2%, respectively. Nox conversion rates and energy costs were also compared for pulsed DC DBD and AC DBD reactors.

  5. TiO2-Supported Binary Metal Oxide Catalysts for Low-temperature Selective Catalytic Reduction of NOx with NH3

    Institute of Scientific and Technical Information of China (English)

    WU Bi-jun; LIU Xiao-qin; XIAO Ping; WANG Shu-gang

    2008-01-01

    Binary metal oxide(MnOx-A/TiO2) catalysts were prepared by adding the second metal to manganese oxides supported on titanium dioxide(TiO2),where,A indicates Fe2O3,WO3,MoO3,and Cr2O3.Their catalytic activity,N2 selectivity,and SO2 poisonous tolerance were investigated.The catalytic performance at low temperatures decreased in the following order:Mn-W/TiO2>Mn-Fe/TiO2>Mn-Cr/TiO2>Mn-Mo/TiO2,whereas the N2 selectivity decreased in the order:Mn-Fe/TiO2>Mn-W/TiO2>Mn-Mo/TiO2>Mn-Cr/TiO2.In the presence of 0.01% SO2 and 6% H2O,the NOx conversions in the presence of Mn-W/TiO2,Mn-Fe/TiO2,or Mn-Mo/TiO2 maintain 98.5%,95.8% and 94.2%,respectively,after 8 h at 120 ℃ at GHSV 12600 h-1.As effective promoters,WO3 and Fe2O3 can increase N2 selectivity and the resistance to SO2 of MnOx/TiO2 significantly.The Fourier transform infrared(FTIR) spectra of NH3 over WO3 show the presence of Lewis acid sites.The results suggest that WO3 is the best promoter of MnOx/TiO2,and Mn-W/TiO2 is one of the most active catalysts for the low temperature selective catalytic reduction of NO with NH3.

  6. Low Temperature Performance of Selective Catalytic Reduction of NO with NH3 under a Concentrated CO2 Atmosphere

    OpenAIRE

    Xiang Gou; Chunfei Wu; Kai Zhang; Guoyou Xu; Meng Si; Yating Wang; Enyu Wang; Liansheng Liu; Jinxiang Wu

    2015-01-01

    Selective catalytic reduction of NOx with NH3 (NH3-SCR) has been widely investigated to reduce NOx emissions from combustion processes, which cause environmental challenges. However, most of the current work on NOx reduction has focused on using feed gas without CO2 or containing small amounts of CO2. In the future, oxy-fuel combustion will play an important role for power generation, and this process generates high concentrations of CO2 in flue gas. Therefore, studies on the SCR process unde...

  7. Catalytic Ammonia Decomposition Over Ruthenium Nanoparticles Supported on Nano-Titanates

    DEFF Research Database (Denmark)

    Klerke, Asbjørn; Klitgaard, Søren Kegnæs; Fehrmann, Rasmus

    2009-01-01

    Nanosized Na2Ti3O7, K2Ti6O13 and Cs2Ti6O13 materials were prepared and used as supports of ruthenium nanoparticles for catalytic ammonia decomposition. It is shown that these catalysts exhibit higher catalytic activity than ruthenium supported on TiO2 nanoparticles promoted with cesium. The diffe...

  8. The Poisoning Effect of Na Doping over Mn-Ce/TiO2 Catalyst for Low-Temperature Selective Catalytic Reduction of NO by NH3

    Directory of Open Access Journals (Sweden)

    Liu Yang

    2014-01-01

    Full Text Available Sodium carbonate (Na2CO3, sodium nitrate (NaNO3, and sodium chloride (NaCl were chosen as the precursors to prepare the Na salts deposited Mn-Ce/TiO2 catalysts through an impregnation method. The influence of Na on the performance of the Mn-Ce/TiO2 catalyst for low-temperature selective catalytic reduction of NOx by NH3 was investigated. Experimental results showed that Na salts had negative effects on the activity of Mn-Ce/TiO2 and the precursors of Na salts also affected the catalytic activity. The precursor Na2CO3 had a greater impact on the catalytic activity, while NaNO3 had minimal effect. The characterization results indicated that the significant changes in physical and chemical properties of Mn-Ce/TiO2 were observed after Na was doped on the catalysts. The significant decreases in surface areas and NH3 adsorption amounts were observed after Na was doped on the catalysts, which could be considered as the main reasons for the deactivation of Na deposited Mn-Ce/TiO2.

  9. Catalytic activity of nanostructured Au: Scale effects versus bimetallic/bifunctional effects in low-temperature CO oxidation on nanoporous Au

    Directory of Open Access Journals (Sweden)

    Lu-Cun Wang

    2013-02-01

    Full Text Available The catalytic properties of nanostructured Au and their physical origin were investigated by using the low-temperature CO oxidation as a test reaction. In order to distinguish between structural effects (structure–activity correlations and bimetallic/bifunctional effects, unsupported nanoporous gold (NPG samples prepared from different Au alloys (AuAg, AuCu by selective leaching of a less noble metal (Ag, Cu were employed, whose structure (surface area, ligament size as well as their residual amount of the second metal were systematically varied by applying different potentials for dealloying. The structural and chemical properties before and after 1000 min reaction were characterized by scanning electron microscopy (SEM, X-ray diffraction (XRD and X-ray photoelectron spectroscopy (XPS. The catalytic behavior was evaluated by kinetic measurements in a conventional microreactor and by dynamic measurements in a temporal analysis of products (TAP reactor. The data reveal a clear influence of the surface contents of residual Ag and Cu species on both O2 activation and catalytic activity, while correlations between activity and structural parameters such as surface area or ligament/crystallite size are less evident. Consequences for the mechanistic understanding and the role of the nanostructure in these NPG catalysts are discussed.

  10. Preparation of Nano-MnFe2O4 and Its Catalytic Performance of Thermal Decomposition of Ammonium Perchlorate

    Institute of Scientific and Technical Information of China (English)

    韩爱军; 廖娟娟; 叶明泉; 李燕; 彭新华

    2011-01-01

    Nano-MnFe2O4 particles were synthesized by co-precipitation phase inversion method and low-temperature combustion method respectively, using MnCl2, FeCl3, Mn(NO3)2, Fe(NO3)3, NaOH and C6H8O7. X-ray diffraction (XRD), transmission electron microscope (TEM), Fourier transform infrared spectroscopy (FT-IR), thermogravim-etry-differential thermal analysis (TG-DTA) and differential scanning calorimetry (DSC) were used to characterize the structure, morphology, thermal stability of MnFe2O4 and its catalytic performance to ammonium perchlorate. Results showed that single-phased and uniform spinel MnFe2O4 was obtained. The average particle size was about 30 and 20 nm. The infrared absorption peaks appeared at about 420 and 574 cm-1, and the particles were stable below 524 ℃. Using the two prepared catalysts, the higher thermal decomposition temperature of ammonium perchlorate was decreased by 77.3 and 84.9 ℃ respectively, while the apparent decomposition heat was increased by 482.5 and 574.3 J?g?1. The catalytic mechanism could be explained by the favorable electron transfer space provided by outer d orbit of transition metal ions and the high specific surface absorption effect of MnFe2O4 particles.

  11. Highly selective catalytic reduction of NO via SO2/H2O-tolerant spinel catalysts at low temperature.

    Science.gov (United States)

    Cai, Xuanxuan; Sun, Wei; Xu, Chaochao; Cao, Limei; Yang, Ji

    2016-09-01

    Selective catalytic reduction of NO X by hydrogen (H2-SCR) in the presence of oxygen has been investigated over the NiCo2O4 and Pd-doped NiCo2O4 catalysts under varying conditions. The catalysts were prepared by a sol-gel method in the presence of oxygen within 50-350 °C and were characterized using XRD, BET, EDS, XPS, Raman, H2-TPR, and NH3-TPD analysis. The results demonstrated that the doped Pd could improve the catalyst reducibility and change the surface acidity and redox properties, resulting in a higher catalytic performance. The performance of NiCo1.95Pd0.05O4 was consistently better than that of NiCo2O4 within the 150-350 °C range at a gas hourly space velocity (GHSV) of 4800 mL g(-1) h(-1), with a feed stream containing 1070 ppm NO, 10,700 ppm H2, 2 % O2, and N2 as balance gas. The effects of GHSV, NO/H2 ratios, and O2 feed concentration on the NO conversion over the NiCo2O4 and NiCo1.95Pd0.05O4 catalysts were also investigated. The two samples similarly showed that an increase in GHSV from 4800 to 9600 mL h(-1) g(-1), the NO/H2 ratio from 1:10 to 1:1, and the O2 content from 0 to 6 % would result in a decrease in NO conversion. In addition, 2 %, 5 %, and 8 % H2O into the feed gas had a slightly negative influence on SCR activity over the two catalysts. The effect of SO2 on the SCR activity indicated that the NiCo1.95Pd0.05O4 possesses better SO2 tolerance than NiCo2O4 catalyst does. Graphical abstract The NiCo1.95Pd0.05O4 catalyst achieved over 90 % NO conversion with N2 selectivity of 100 % in the 200∼250 °C range than the maximum 40.5 % NO conversion over NiCo2O4 with N2 selectivity of approximately 80 % in 350 °C.

  12. Low-temperature selective catalytic reduction of NO with NH3 over nanoflaky MnOx on carbon nanotubes in situ prepared via a chemical bath deposition route

    Science.gov (United States)

    Fang, Cheng; Zhang, Dengsong; Cai, Sixiang; Zhang, Lei; Huang, Lei; Li, Hongrui; Maitarad, Phornphimon; Shi, Liyi; Gao, Ruihua; Zhang, Jianping

    2013-09-01

    Nanoflaky MnOx on carbon nanotubes (nf-MnOx@CNTs) was in situ synthesized by a facile chemical bath deposition route for low-temperature selective catalytic reduction (SCR) of NO with NH3. This catalyst was mainly characterized by the techniques of X-ray diffraction (XRD), transmission electron microscopy (TEM), scanning electron microscopy (SEM), N2 adsorption-desorption analysis, X-ray photoelectron spectroscopy (XPS), H2 temperature-programmed reduction (H2-TPR) and NH3 temperature-programmed desorption (NH3-TPD). The SEM, TEM, XRD results and N2 adsorption-desorption analysis indicated that the CNTs were surrounded by nanoflaky MnOx and the obtained catalyst exhibited a large surface area as well. Compared with the MnOx/CNT and MnOx/TiO2 catalysts prepared by an impregnation method, the nf-MnOx@CNTs presented better NH3-SCR activity at low temperature and a more extensive operating temperature window. The XPS results showed that a higher atomic concentration of Mn4+ and more chemisorbed oxygen species existed on the surface of CNTs for nf-MnOx@CNTs. The H2-TPR and NH3-TPD results demonstrated that the nf-MnOx@CNTs possessed stronger reducing ability, more acid sites and stronger acid strength than the other two catalysts. Based on the above mentioned favourable properties, the nf-MnOx@CNT catalyst has an excellent performance in the low-temperature SCR of NO to N2 with NH3. In addition, the nf-MnOx@CNT catalyst also presented favourable stability and H2O resistance.Nanoflaky MnOx on carbon nanotubes (nf-MnOx@CNTs) was in situ synthesized by a facile chemical bath deposition route for low-temperature selective catalytic reduction (SCR) of NO with NH3. This catalyst was mainly characterized by the techniques of X-ray diffraction (XRD), transmission electron microscopy (TEM), scanning electron microscopy (SEM), N2 adsorption-desorption analysis, X-ray photoelectron spectroscopy (XPS), H2 temperature-programmed reduction (H2-TPR) and NH3 temperature

  13. MnOx-CeO2 catalysts supported by Ti-Bearing Blast Furnace Slag for selective catalytic reduction of NO with NH3 at low temperature.

    Science.gov (United States)

    Xu, Yifan; Liu, Rong; Ye, Fei; Jia, Feng; Ji, Lingchen

    2017-03-13

    A series of MnOx-CeO2 catalysts supported by Ti-bearing blast furnace slag were prepared by wet impregnation and used for low-temperature selective catalytic reduction (SCR) of NO with NH3. The slag-based catalyst exhibited high deNOx activity and wide effective temperature range. Under the condition of NO=500ppm, NH3=500ppm, O2:7-8vol% and total flow rate=1600 ml/min, the Mn-Ce/Slag catalyst exhibited a NO conversion higher than 95% in the range of 180-260 °C. The activity of Mn/Slag catalysts was greatly enhanced with the addition of CeO2. The results indicated that Ti-bearing blast furnace slag had suitable phase composition as good support of SCR catalyst.

  14. Characterization and Catalytic Activity of Mn-Co/TiO2 Catalysts for NO Oxidation to NO2 at Low Temperature

    Directory of Open Access Journals (Sweden)

    Lu Qiu

    2016-01-01

    Full Text Available A series of Mn-Co/TiO2 catalysts were prepared by wet impregnation method and evaluated for the oxidation of NO to NO2. The effects of Co amounts and calcination temperature on NO oxidation were investigated in detail. The catalytic oxidation ability in the temperature range of 403–473 K was obviously improved by doping cobalt into Mn/TiO2. These samples were characterized by nitrogen adsorption-desorption, X-ray diffraction (XRD, X-ray photoelectron spectroscopy (XPS, transmission electron microscope (TEM and hydrogen temperature programmed reduction (H2-TPR. The results indicated that the formation of dispersed Co3O4·CoMnO3 mixed oxides through synergistic interaction between Mn-O and Co-O was directly responsible for the enhanced activities towards NO oxidation at low temperatures. Doping of Co enhanced Mn4+ formation and increased chemical adsorbed oxygen amounts, which also accelerated NO oxidation.

  15. Facile preparation of ordered mesoporous MnCo2O4 for low-temperature selective catalytic reduction of NO with NH3

    Science.gov (United States)

    Qiu, Mingying; Zhan, Sihui; Yu, Hongbing; Zhu, Dandan; Wang, Shengqiang

    2015-01-01

    Ordered mesoporous MnCo2O4 nanomaterials were successfully prepared through the nanocasting route using SBA-15 and KIT-6 as hard templates. These mesoporous nanomaterials were characterized using XRD, BET, TEM, NH3-TPD, H2-TPR, NO-TPD, XPS and DRIFT. The low temperature selective catalytic reduction (SCR) activity of NO with NH3 was investigated, which revealed that 3D-MnCo2O4 using KIT-6 as a template can totally clean all NO over a wide temperature range of 100-250 °C with a gas hourly space velocity (GHSV) of 32 000 h-1, while 2D-MnCo2O4 with SBA-15 as a template had 95% conversion rate at the same condition. 3D-MnCo2O4 showed the best performance to clean NO due to its typical three-dimensional porous structure, large specific surface area, abundant active surface oxygen species and Lewis acid sites. All the results indicate that a novel, cheap catalyst for catalytic removal of NO can be designed by controlling the morphology at the nanoscale.Ordered mesoporous MnCo2O4 nanomaterials were successfully prepared through the nanocasting route using SBA-15 and KIT-6 as hard templates. These mesoporous nanomaterials were characterized using XRD, BET, TEM, NH3-TPD, H2-TPR, NO-TPD, XPS and DRIFT. The low temperature selective catalytic reduction (SCR) activity of NO with NH3 was investigated, which revealed that 3D-MnCo2O4 using KIT-6 as a template can totally clean all NO over a wide temperature range of 100-250 °C with a gas hourly space velocity (GHSV) of 32 000 h-1, while 2D-MnCo2O4 with SBA-15 as a template had 95% conversion rate at the same condition. 3D-MnCo2O4 showed the best performance to clean NO due to its typical three-dimensional porous structure, large specific surface area, abundant active surface oxygen species and Lewis acid sites. All the results indicate that a novel, cheap catalyst for catalytic removal of NO can be designed by controlling the morphology at the nanoscale. Electronic supplementary information (ESI) available: Low-angle XRD

  16. Low Temperature Performance of Selective Catalytic Reduction of NO with NH3 under a Concentrated CO2 Atmosphere

    Directory of Open Access Journals (Sweden)

    Xiang Gou

    2015-10-01

    Full Text Available Selective catalytic reduction of NOx with NH3 (NH3-SCR has been widely investigated to reduce NOx emissions from combustion processes, which cause environmental challenges. However, most of the current work on NOx reduction has focused on using feed gas without CO2 or containing small amounts of CO2. In the future, oxy-fuel combustion will play an important role for power generation, and this process generates high concentrations of CO2 in flue gas. Therefore, studies on the SCR process under concentrated CO2 atmosphere conditions are important for future SCR deployment in oxy-fuel combustion processes. In this work, Mn- and Ce-based catalysts using activated carbon as support were used to investigate the effect of CO2 on NO conversion. A N2 atmosphere was used for comparison. Different process conditions such as temperature, SO2 concentration, H2O content in the feed gas and space velocity were studied. Under Mn-Ce/AC conditions, the results suggested that Mn metal could reduce the inhibition effect of CO2 on the NO conversion, while Ce metal increased the inhibition effect of CO2. High space velocity also resulted in a reduction of CO2 inhibition on the NO conversion, although the overall performance of SCR was greatly reduced at high space velocity. Future investigations to design novel Mn-based catalysts are suggested to enhance the SCR performance under concentrated CO2 atmosphere conditions.

  17. Low-temperature selective catalytic reduction of NO with NH₃ over nanoflaky MnOx on carbon nanotubes in situ prepared via a chemical bath deposition route.

    Science.gov (United States)

    Fang, Cheng; Zhang, Dengsong; Cai, Sixiang; Zhang, Lei; Huang, Lei; Li, Hongrui; Maitarad, Phornphimon; Shi, Liyi; Gao, Ruihua; Zhang, Jianping

    2013-10-07

    Nanoflaky MnO(x) on carbon nanotubes (nf-MnO(x)@CNTs) was in situ synthesized by a facile chemical bath deposition route for low-temperature selective catalytic reduction (SCR) of NO with NH₃. This catalyst was mainly characterized by the techniques of X-ray diffraction (XRD), transmission electron microscopy (TEM), scanning electron microscopy (SEM), N₂ adsorption-desorption analysis, X-ray photoelectron spectroscopy (XPS), H₂ temperature-programmed reduction (H₂-TPR) and NH₃ temperature-programmed desorption (NH₃-TPD). The SEM, TEM, XRD results and N₂ adsorption-desorption analysis indicated that the CNTs were surrounded by nanoflaky MnO(x) and the obtained catalyst exhibited a large surface area as well. Compared with the MnO(x)/CNT and MnO(x)/TiO₂ catalysts prepared by an impregnation method, the nf-MnO(x)@CNTs presented better NH₃-SCR activity at low temperature and a more extensive operating temperature window. The XPS results showed that a higher atomic concentration of Mn(4+) and more chemisorbed oxygen species existed on the surface of CNTs for nf-MnO(x)@CNTs. The H₂-TPR and NH₃-TPD results demonstrated that the nf-MnO(x)@CNTs possessed stronger reducing ability, more acid sites and stronger acid strength than the other two catalysts. Based on the above mentioned favourable properties, the nf-MnO(x)@CNT catalyst has an excellent performance in the low-temperature SCR of NO to N₂ with NH₃. In addition, the nf-MnO(x)@CNT catalyst also presented favourable stability and H₂O resistance.

  18. Integrated Removal of NOx with Carbon Monoxide as Reductant, and Capture of Mercury in a Low Temperature Selective Catalytic and Adsorptive Reactor

    Energy Technology Data Exchange (ETDEWEB)

    Neville Pinto; Panagiotis Smirniotis; Stephen Thiel

    2010-08-31

    Coal will likely continue to be a dominant component of power generation in the foreseeable future. This project addresses the issue of environmental compliance for two important pollutants: NO{sub x} and mercury. Integration of emission control units is in principle possible through a Low Temperature Selective Catalytic and Adsorptive Reactor (LTSCAR) in which NO{sub x} removal is achieved in a traditional SCR mode but at low temperature, and, uniquely, using carbon monoxide as a reductant. The capture of mercury is integrated into the same process unit. Such an arrangement would reduce mercury removal costs significantly, and provide improved control for the ultimate disposal of mercury. The work completed in this project demonstrates that the use of CO as a reductant in LTSCR is technically feasible using supported manganese oxide catalysts, that the simultaneous warm-gas capture of elemental and oxidized mercury is technically feasible using both nanostructured chelating adsorbents and ceria-titania-based materials, and that integrated removal of mercury and NO{sub x} is technically feasible using ceria-titania-based materials.

  19. Novel ultrasonic-modified MnOx/TiO2 for low-temperature selective catalytic reduction (SCR) of NO with ammonia.

    Science.gov (United States)

    Zhang, Yaping; Zhao, Xiaoyuan; Xu, Haitao; Shen, Kai; Zhou, Changcheng; Jin, Baosheng; Sun, Keqin

    2011-09-01

    A novel ultrasonic-modified MnO(x)/TiO(2) catalyst was prepared and compared with two different kinds of MnO(x)/TiO(2) catalysts in the process of low-temperature selective catalytic reduction of NO with NH(3). The physicochemical properties of the catalysts were studied by using various characterization techniques, such as Brunauer-Emmett-Teller (BET) surface measurement, X-ray diffraction (XRD), high-resolution transmission electron microscope (HRTEM), and in situ Fourier transform infrared spectroscopy (in situ FT-IR). The ultrasonic-modified process introduced ultrasound in the solution impregnation step of traditional impregnation method for MnO(x)/TiO(2) catalyst preparation. In this study, ultrasonic process significantly improved the dispersion behavior and surface acid property of manganese oxide on TiO(2) as well as the catalytic activity, especially at temperature below 120°C. The NO conversion could reach 90% at 100°C. For the novel ultrasonic-modified catalyst, the combination analysis of XRD and HRTEM confirmed that manganese oxide was in a highly dispersed state and Ti and Mn had strong interaction. Furthermore, in situ FT-IR studies revealed that there were significant amounts of Lewis acidity and high Mn atom concentration on the surface of the novel catalysts.

  20. 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.

  1. Low temperature selective catalytic reduction of NO by C3H6 over CeOx loaded on AC treated by HNO3

    Institute of Scientific and Technical Information of China (English)

    楚英豪; 尹华强; 张腾腾; 朱晓帆; 郭家秀; 刘勇军; 刘超

    2015-01-01

    The activated carbons from coal were treated by HNO3 (named as NAC) and used as carriers to load 7% Ce (named as Ce(0.07)/NAC) by impregnation method. The physical and chemical properties were investigated by thermogravimetric-differential thermal analysis (TG-DTA), Brunauer-Emmett-Teller (BET), X-ray diffraction (XRD), X-ray photoelectron spectra (XPS), scanning electron microscopy (SEM) and NH3-temperature programmed desorption (NH3-TPD) and NO-temperature programmed desorption techniques. The catalytic activities of Ce(0.07)/NAC were evaluated for the low temperature selective catalytic reduction (SCR) of NO with C3H6 using temperature-programmed reaction (TP-reaction) in NO, C3H6, O2 and N2 as a balance. The results showed that the specific surface area of Ce(0.07)/NAC was 850.8 m2/g and less than NAC, but Ce oxides could be dispersed highly on the acti-vated carbons. Ce oxides could change acid sites and NO adsorption as well as oxygen-containing functional groups of activated car-bons, and Ce4+ and Ce3+ coexisted in catalysts. The conversion of NO with C3H6 achieved 70% at 280 °C over Ce(0.07)/NAC, but with the increase of O2 concentration, heat accumulation and nonselective combustion were exacerbated, which could cause surface ashing and roughness, resulting in a sharp decrease of catalytic activities. The optimum O2 concentration used in the reaction system was 3% and achieved the high conversion of NO and the widest temperature window. The conversion of NO was closely related to the NO concentrations and [NO]/[C3H6] ratios, and the stoichiometric number was just close to 2:1, but the presence of H2O could af-fect the denitration efficiency of catalyst.

  2. Catalytic decomposition of low level ozone with gold nanoparticles supported on activated carbon

    Institute of Scientific and Technical Information of China (English)

    Pengyi ZHANG; Bo ZHANG; Rui SHI

    2009-01-01

    Highly dispersed gold nanoparticles were supported on coal-based activated carbon (AC) by a sol immobilization method and were used to investigate their catalytic activity for low-level ozone decomposition at ambient temperature. Nitrogen adsorption-desorption,scanning electron microscope (SEM), and X-ray photo-electron spectroscopy (XPS) were used to characterize the catalysts before and after ozone decomposition. The results showed that the supported gold nanoparticles prepared with microwave heating were much smaller and more uniformly dispersed on the activated carbon than those prepared with traditional conduction heating, exhibiting higher catalytic activity for ozone decomposition. The pH values of gold precursor solution significantly influenced the catalytic activity of supported gold for ozone decomposition, and the best pH value was 8. In the case of space velocity of 120000 h-1, inlet ozone concentration of 50mg/m3, and relative humidity of 45%, the Au/AC catalyst maintained the ozone removal ratio at 90.7% after 2500 min. After being used for ozone decomposition, the surface carbon of the catalyst was partly oxidized and the oxygen content increased accordingly, while its specific surface area and pore volume only decreased a little.Ozone was mainly catalytically decomposed by the gold nanoparticles supported on the activated carbon.

  3. In situ spectroscopic studies on vapor phase catalytic decomposition of dimethyl oxalate.

    Science.gov (United States)

    Hegde, Shweta; Tharpa, Kalsang; Akuri, Satyanarayana Reddy; K, Rakesh; Kumar, Ajay; Deshpande, Raj; Nair, Sreejit A

    2017-03-15

    Dimethyl Oxalate (DMO) has recently gained prominence as a valuable intermediate for the production of compounds of commercial importance. The stability of DMO is poor and hence this can result in the decomposition of DMO under reaction conditions. The mechanism of DMO decomposition is however not reported and more so on catalytic surfaces. Insights into the mechanism of decomposition would help in designing catalysts for its effective molecular transformation. It is well known that DMO is sensitive to moisture, which can also be a factor contributing to its decomposition. The present work reports the results of decomposition of DMO on various catalytic materials. The materials studied consist of acidic (γ-Al2O3), basic (MgO), weakly acidic (ZnAl2O4) and neutral surfaces such as α-Al2O3 and mesoporous precipitated SiO2. Infrared spectroscopy is used to identify the nature of adsorption of the molecule on the various surfaces. The spectroscopy study is done at a temperature of 200 °C, which is the onset of gas phase decomposition of DMO. The results indicate that the stability of DMO is lower than the corresponding acid, i.e. oxalic acid. It is also one of the products of decomposition. Spectroscopic data suggest that DMO decomposition is related to surface acidity and the extent of decomposition depends on the number of surface hydroxyl groups. Decomposition was also observed on α-Al2O3, which was attributed to the residual surface hydroxyl groups. DMO decomposition to oxalic acid was not observed on the basic surface (MgO).

  4. Energy Diagram for the Catalytic Decomposition of Hydrogen Peroxide

    Science.gov (United States)

    Tatsuoka, Tomoyuki; Koga, Nobuyoshi

    2013-01-01

    Drawing a schematic energy diagram for the decomposition of H[subscript 2]O[subscript 2] catalyzed by MnO[subscript 2] through a simple thermometric measurement outlined in this study is intended to integrate students' understanding of thermochemistry and kinetics of chemical reactions. The reaction enthalpy, delta[subscript r]H, is…

  5. In situ supported MnO(x)-CeO(x) on carbon nanotubes for the low-temperature selective catalytic reduction of NO with NH3.

    Science.gov (United States)

    Zhang, Dengsong; Zhang, Lei; Shi, Liyi; Fang, Cheng; Li, Hongrui; Gao, Ruihua; Huang, Lei; Zhang, Jianping

    2013-02-07

    The MnO(x) and CeO(x) were in situ supported on carbon nanotubes (CNTs) by a poly(sodium 4-styrenesulfonate) assisted reflux route for the low-temperature selective catalytic reduction (SCR) of NO with NH(3). X-Ray diffraction (XRD), transmission electron microscopy (TEM), high-resolution TEM (HRTEM), X-ray photoelectron spectroscopy (XPS), H(2) temperature-programmed reduction (H(2)-TPR) and NH(3) temperature-programmed desorption (NH(3)-TPD) have been used to elucidate the structure and surface properties of the obtained catalysts. It was found that the in situ prepared catalyst exhibited the highest activity and the most extensive operating-temperature window, compared to the catalysts prepared by impregnation or mechanically mixed methods. The XRD and TEM results indicated that the manganese oxide and cerium oxide species had a good dispersion on the CNT surface. The XPS results demonstrated that the higher atomic concentration of Mn existed on the surface of CNTs and the more chemisorbed oxygen species exist. The H(2)-TPR results suggested that there was a strong interaction between the manganese oxide and cerium oxide on the surface of CNTs. The NH(3)-TPD results demonstrated that the catalysts presented a larger acid amount and stronger acid strength. In addition, the obtained catalysts exhibited much higher SO(2)-tolerance and improved the water-resistance as compared to that prepared by impregnation or mechanically mixed methods.

  6. Mechanism of N2O formation during the low-temperature selective catalytic reduction of NO with NH3 over Mn-Fe spinel.

    Science.gov (United States)

    Yang, Shijian; Xiong, Shangchao; Liao, Yong; Xiao, Xin; Qi, Feihong; Peng, Yue; Fu, Yuwu; Shan, Wenpo; Li, Junhua

    2014-09-02

    The mechanism of N2O formation during the low-temperature selective catalytic reduction reaction (SCR) over Mn-Fe spinel was studied. The in situ diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS) and transient reaction studies demonstrated that the Eley-Rideal mechanism (i.e., the reaction of adsorbed NH3 species with gaseous NO) and the Langmuir-Hinshelwood mechanism (i.e., the reaction of adsorbed NH3 species with adsorbed NOx species) both contributed to N2O formation. However, N2O selectivity of NO reduction over Mn-Fe spinel through the Langmuir-Hinshelwood mechanism was much less than that through the Eley-Rideal mechanism. The ratio of NO reduction over Mn-Fe spinel through the Langmuir-Hinshelwood mechanism remarkably increased; therefore, N2O selectivity of NO reduction over Mn-Fe spinel decreased with the decrease of the gas hourly space velocity (GHSV). As the gaseous NH3 concentration increased, N2O selectivity of NO reduction over Mn-Fe spinel increased because of the promotion of NO reduction through the Eley-Rideal mechanism. Meanwhile, N2O selectivity of NO reduction over Mn-Fe spinel decreased with the increase of the gaseous NO concentration because the formation of NH on Mn-Fe spinel was restrained. Therefore, N2O selectivity of NO reduction over Mn-Fe spinel was related to the GHSV and concentrations of reactants.

  7. In situ IR studies of Co and Ce doped Mn/TiO2 catalyst for low-temperature selective catalytic reduction of NO with NH3

    Science.gov (United States)

    Qiu, Lu; Pang, Dandan; Zhang, Changliang; Meng, Jiaojiao; Zhu, Rongshu; Ouyang, Feng

    2015-12-01

    The Mn-Co-Ce/TiO2 catalyst was prepared by wet co-impregnation method for selective catalytic reduction of NO by NH3 in the presence of oxygen. The adsorption and co-adsorption of NH3, NO and O2 on catalysts were investigated by in situ FTIR spectroscopy. The results suggested that addition of cobalt and cerium oxides increased the numbers of acid and redox sites. Especially, the cobalt oxide produced lots of Brønsted acid sites, which favor to the adsorption of coordinated NH3 through NH3 migration. Ce addition improved amide ions formation to reach best NO reduction selectivity. A mechanistic pathway over Mn-Co-Ce/TiO2 was proposed. At low-temperature SCR reaction, coordinated NH3 reacted with NO2-, and amide reacted with NO (ad) or NO (g) to form N2. NO2 was related to the formation of nitrite on Co-contained catalysts and the generation of sbnd NH2- on Ce-contained catalysts. At high temperature, the other branch reaction also occurred between the coordinated NH3 and nitrate species, resulting in N2O yield increase.

  8. Catalytic decomposition of hydrogen peroxide on anthraquinonecyanine and phthalocyanine metal complexes in acid and alkaline electrolytes

    Energy Technology Data Exchange (ETDEWEB)

    Pobedinskiy, S.N.; Trofimenko, A.A.; Zharnikova, M.A.

    1985-12-01

    A study of octaoxyanthraquinonecyanines (OOATsM) and phthalocyanines (FTs) of cobalt, iron, and manganese determined their catalytic activity in the hydrogen peroxide decomposition reaction. Hydrogen peroxide decomposition on OOATsM and FTs of the metals studied follows the kinetic mechanisms of a reaction of the first order regardless of the central ion of the metal. Complexes with a central atom of iron are most active in decomposition of hydrogen peroxide. Catalytic activity of FTsFe exceeds that of FTsCo more than 10-fold. FTs are 10-fold greater than OOATsM in catalytic activity. Change from an acid to an alkali medium did not affect the kinetic mechanisms of the decomposition reaction but the reaction rate on both a carrier and on metal complexes is higher in an alkaline medium than in an acid medium. The affect of an alkaline medium on the hydrogen peroxide decomposition rate is greater for FTS complexes than for anthraquinone-cyanines. 5 references, 2 figures.

  9. Catalytic non-thermal plasma reactor for the decomposition of a mixture of volatile organic compounds

    Indian Academy of Sciences (India)

    B Rama Raju; E Linga Reddy; J Karuppiah; P Manoj Kumar Reddy; Ch Subrahmanyam

    2013-05-01

    The decomposition of mixture of selected volatile organic compounds (VOCs) has been studied in a catalytic non-thermal plasma dielectric barrier discharge reactor. The VOCs mixture consisting n-hexane, cyclo-hexane and -xylene was chosen for the present study. The decomposition characteristics of mixture of VOCs by the DBD reactor with inner electrode modified with metal oxides of Mn and Co was studied. The results indicated that the order of the removal efficiency of VOCs followed as -xylene > cyclo-hexane > -hexane. Among the catalytic study, MnOx/SMF (manganese oxide on sintered metal fibres electrode) shows better performance, probably due to the formation of active oxygen species by in situ decomposition of ozone on the catalyst surface. Water vapour further enhanced the performance due to the in situ formation of OH radicals.

  10. IN SITU INFRARED STUDY OF CATALYTIC DECOMPOSITION OF NITRIC OXIDE (NO)

    Energy Technology Data Exchange (ETDEWEB)

    Unknown

    1999-12-31

    The growing concerns for the environment and increasingly stringent standards for NO emission have presented a major challenge to control NO emissions from electric utility plants and automobiles. Catalytic decomposition of NO is the most attractive approach for the control of NO emission for its simplicity. Successful development of an effective catalyst for NO decomposition will greatly decrease the equipment and operation cost of NO control. Due to lack of understanding of the mechanism of NO decomposition, efforts on the search of an effective catalyst have been unsuccessful. Scientific development of an effective catalyst requires fundamental understanding of the nature of active site, the rate-limiting step, and an approach to prolong the life of the catalyst. The authors have investigated the feasibility of two novel approaches for improving catalyst activity and resistance to sintering. The first approach is the use of silanation to stabilize metal crystallites and supports for Cu-ZSM-5 and promoted Pt catalysts; the second is utilization of oxygen spillover and desorption to enhance NO decomposition activity. The silanation approach failed to stabilize Cu-ZSM-5 activity under hydrothermal condition. Silanation blocked the oxygen migration and inhibited oxygen desorption. Oxygen spillover was found to be an effective approach for promoting NO decomposition activity on Pt-based catalysts. Detailed mechanistic study revealed the oxygen inhibition in NO decomposition and reduction as the most critical issue in developing an effective catalytic approach for controlling NO emission.

  11. Catalytic decomposition of N₂O over CeO₂ supported Co₃O₄ catalysts

    Indian Academy of Sciences (India)

    S K MAHAMMADUNNISA; T AKANKSHA; K KRUSHNAMURTY; CH SUBRAHMANYAM

    2016-11-01

    This work was aimed to design efficient catalysts for N₂O decomposition at low temperatures. Cobalt oxide (Co₃O₄) was prepared by hydrothermal, precipitation and combustion methods and tested for N₂O decomposition. It was found that the catalysts prepared by solution combustion synthesis were most active for this reaction. Subsequently, a series of ceria (CeO₂) supported Co₃O₄ catalysts (xCeCo) were prepared by solution combustion method and used them for N₂O decomposition. All the catalysts were characterized by analytical methods like XRD, TEM, BET, XPS, UV-Vis, Raman and H2-TPR. It was found that 10 and 20 wt..% loading of CeO₂ on Co₃O₄ promoted the activity of Co₃O₄ towards N₂O decomposition, whereas, higher loading of CeO₂ reduced the activity. Typical results indicated that addition of CeO₂ increases the surface area of Co₃O₄ , and improves the reduction of Co³⁺ to Co²⁺ by facilitating the desorption of adsorbed oxygen species, which is the rate-determining step for the N₂O decomposition over Co₃O₄ spinel catalysts. Optimal CeO₂ loading can increase both dispersion and surface area of Co₃O₄ catalysts and weaken the Co–O bond strength to promote N₂O decomposition.

  12. Catalytic effects of inorganic acids on the decomposition of ammonium nitrate.

    Science.gov (United States)

    Sun, Jinhua; Sun, Zhanhui; Wang, Qingsong; Ding, Hui; Wang, Tong; Jiang, Chuansheng

    2005-12-09

    In order to evaluate the catalytic effects of inorganic acids on the decomposition of ammonium nitrate (AN), the heat releases of decomposition or reaction of pure AN and its mixtures with inorganic acids were analyzed by a heat flux calorimeter C80. Through the experiments, the different reaction mechanisms of AN and its mixtures were analyzed. The chemical reaction kinetic parameters such as reaction order, activation energy and frequency factor were calculated with the C80 experimental results for different samples. Based on these parameters and the thermal runaway models (Semenov and Frank-Kamenestkii model), the self-accelerating decomposition temperatures (SADTs) of AN and its mixtures were calculated and compared. The results show that the mixtures of AN with acid are more unsteady than pure AN. The AN decomposition reaction is catalyzed by acid. The calculated SADTs of AN mixtures with acid are much lower than that of pure AN.

  13. Nitrated graphene oxide and its catalytic activity in thermal decomposition of ammonium perchlorate

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Wenwen; Luo, Qingping; Duan, Xiaohui [State Key Laboratory Cultivation Base for Nonmetal Composites and Functional Materials, Southwest University of Science and Technology, Mianyang 621010 (China); Zhou, Yong [Eco-materials and Renewable Energy Research Center (ERERC), School of Physics, National Lab of Solid State Microstructure, ERERC, Nanjing University, Nanjing 210093 (China); Pei, Chonghua, E-mail: peichonghua@swust.edu.cn [State Key Laboratory Cultivation Base for Nonmetal Composites and Functional Materials, Southwest University of Science and Technology, Mianyang 621010 (China)

    2014-02-01

    Highlights: • The NGO was synthesized by nitrifying homemade GO. • The N content of resulted NGO is up to 1.45 wt.%. • The NGO can facilitate the decomposition of AP and release much heat. - Abstract: Nitrated graphene oxide (NGO) was synthesized by nitrifying homemade GO with nitro-sulfuric acid. Fourier transform infrared spectroscopy (FTIR), laser Raman spectroscopy, CP/MAS {sup 13}C NMR spectra and X-ray photoelectron spectroscopy (XPS) were used to characterize the structure of NGO. The thickness and the compositions of GO and NGO were analyzed by atomic force microscopy (AFM) and elemental analysis (EA), respectively. The catalytic effect of the NGO for the thermal decomposition of ammonium perchlorate (AP) was investigated by differential scanning calorimetry (DSC). Adding 10% of NGO to AP decreases the decomposition temperature by 106 °C and increases the apparent decomposition heat from 875 to 3236 J/g.

  14. In situ supported MnOx-CeOx on carbon nanotubes for the low-temperature selective catalytic reduction of NO with NH3

    Science.gov (United States)

    Zhang, Dengsong; Zhang, Lei; Shi, Liyi; Fang, Cheng; Li, Hongrui; Gao, Ruihua; Huang, Lei; Zhang, Jianping

    2013-01-01

    The MnOx and CeOx were in situ supported on carbon nanotubes (CNTs) by a poly(sodium 4-styrenesulfonate) assisted reflux route for the low-temperature selective catalytic reduction (SCR) of NO with NH3. X-Ray diffraction (XRD), transmission electron microscopy (TEM), high-resolution TEM (HRTEM), X-ray photoelectron spectroscopy (XPS), H2 temperature-programmed reduction (H2-TPR) and NH3 temperature-programmed desorption (NH3-TPD) have been used to elucidate the structure and surface properties of the obtained catalysts. It was found that the in situ prepared catalyst exhibited the highest activity and the most extensive operating-temperature window, compared to the catalysts prepared by impregnation or mechanically mixed methods. The XRD and TEM results indicated that the manganese oxide and cerium oxide species had a good dispersion on the CNT surface. The XPS results demonstrated that the higher atomic concentration of Mn existed on the surface of CNTs and the more chemisorbed oxygen species exist. The H2-TPR results suggested that there was a strong interaction between the manganese oxide and cerium oxide on the surface of CNTs. The NH3-TPD results demonstrated that the catalysts presented a larger acid amount and stronger acid strength. In addition, the obtained catalysts exhibited much higher SO2-tolerance and improved the water-resistance as compared to that prepared by impregnation or mechanically mixed methods.The MnOx and CeOx were in situ supported on carbon nanotubes (CNTs) by a poly(sodium 4-styrenesulfonate) assisted reflux route for the low-temperature selective catalytic reduction (SCR) of NO with NH3. X-Ray diffraction (XRD), transmission electron microscopy (TEM), high-resolution TEM (HRTEM), X-ray photoelectron spectroscopy (XPS), H2 temperature-programmed reduction (H2-TPR) and NH3 temperature-programmed desorption (NH3-TPD) have been used to elucidate the structure and surface properties of the obtained catalysts. It was found that the in situ

  15. Synergy of CuO and CeO2 combination for mercury oxidation under low-temperature selective catalytic reduction atmosphere

    KAUST Repository

    Li, Hailong

    2016-07-19

    Synergy for low temperature Hg0 oxidation under selective catalytic reduction (SCR) atmosphere was achieved when copper oxides and cerium oxides were combined in a CuO-CeO2/TiO2 (CuCeTi) catalyst. Hg0 oxidation efficiency as high as 99.0% was observed on the CuCeTi catalyst at 200 °C, even the gas hourly space velocity was extremely high. To analyze the synergistic effect, comparisons of catalyst performance in the presence of different SCR reaction gases were systematically conducted over CuO/TiO2 (CuTi), CeO2/TiO2 (CeTi) and CuCeTi catalysts prepared by sol-gel method. The interactions between copper oxides and cerium oxides in CuCeTi catalyst yielded more surface chemisorbed oxygen, and facilitated the conversion of gas-phase O2 to surface oxygen, which are favorable for Hg0 oxidation. Copper oxides in the combination interacted with NO forming more chemisorbed oxygen for Hg0 oxidation in the absence of gas-phase O2. Cerium oxides in the combination promoted Hg0 oxidation through enhancing the transformations of NO to NO2. In the absence of NO, NH3 exhibited no inhibitive effect on Hg0 oxidation, because enough Lewis acid sites due to the combination of copper oxides and cerium oxides scavenged the competitive adsorption between NH3 and Hg0. In the presence of NO, although NH3 lowered Hg0 oxidation rate through inducing reduction of oxidized mercury, complete recovery of Hg0 oxidation activity over the CuCeTi catalyst was quickly achieved after cutting off NH3. This study revealed the synergistic effect of the combination of copper oxides and cerium oxides on Hg0 oxidation, and explored the involved mechanisms. Such knowledge would help obtaining maximum Hg0 oxidation co-benefit from SCR units in coal-fired power plants.

  16. Catalytic hydrothermal processing of microalgae: decomposition and upgrading of lipids.

    Science.gov (United States)

    Biller, P; Riley, R; Ross, A B

    2011-04-01

    Hydrothermal processing of high lipid feedstock such as microalgae is an alternative method of oil extraction which has obvious benefits for high moisture containing biomass. A range of microalgae and lipids extracted from terrestrial oil seed have been processed at 350 °C, at pressures of 150-200 bar in water. Hydrothermal liquefaction is shown to convert the triglycerides to fatty acids and alkanes in the presence of certain heterogeneous catalysts. This investigation has compared the composition of lipids and free fatty acids from solvent extraction to those from hydrothermal processing. The initial decomposition products include free fatty acids and glycerol, and the potential for de-oxygenation using heterogeneous catalysts has been investigated. The results indicate that the bio-crude yields from the liquefaction of microalgae were increased slightly with the use of heterogeneous catalysts but the higher heating value (HHV) and the level of de-oxygenation increased, by up to 10%. Copyright © 2011 Elsevier Ltd. All rights reserved.

  17. Solar production of catalytic filamentous carbon by thermal decomposition of hydrocarbons and carbon monoxide

    Energy Technology Data Exchange (ETDEWEB)

    Kirillov, V.A.; Kuvshinov, G.G.; Mogilnykh, Yu.I. [Boreskov Institute of Catalysis, Novosibirsk (Russian Federation); Reller, A. [University of Hamburg (Germany); Steinfeld, A.; Weidenkaff, A.; Meier, A. [Paul Scherrer Inst. (PSI), Villigen (Switzerland)

    1999-08-01

    Concentrated solar radiation was used as the clean source of process heat for the production of Catalytic Filamentous Carbon (CFC) by thermal decomposition of gaseous hydrocarbons and by CO disproportionation in the presence of small metal catalyst particles. Depending on the catalyst, two different types of CFC, namely nano tubes and nano fibers, were obtained in solar experiments at the PSI solar furnace. (author) 2 figs., 1 tab., 7 refs.

  18. Ruthenium-catalysed decomposition of formic acid: Fuel cell and catalytic applications

    KAUST Repository

    Piola, Lorenzo

    2017-08-08

    The decomposition of formic acid into H2 and CO2 was successfully performed using a ruthenium hydride catalyst, without any concomitant CO evolution. The reaction mechanism is investigated by means of density functional theory calculations (DFT). The generated H2 was further exploited in a fuel cell to produce electricity. The catalytic hydrogenation of conjugated olefins, using this dihydrogen generation procedure, is also reported.

  19. Catalytic Decomposition of Hydroxylammonium Nitrate Ionic Liquid: Enhancement of NO Formation.

    Science.gov (United States)

    Chambreau, Steven D; Popolan-Vaida, Denisia M; Vaghjiani, Ghanshyam L; Leone, Stephen R

    2017-05-18

    Hydroxylammonium nitrate (HAN) is a promising candidate to replace highly toxic hydrazine in monopropellant thruster space applications. The reactivity of HAN aerosols on heated copper and iridium targets was investigated using tunable vacuum ultraviolet photoionization time-of-flight aerosol mass spectrometry. The reaction products were identified by their mass-to-charge ratios and their ionization energies. Products include NH3, H2O, NO, hydroxylamine (HA), HNO3, and a small amount of NO2 at high temperature. No N2O was detected under these experimental conditions, despite the fact that N2O is one of the expected products according to the generally accepted thermal decomposition mechanism of HAN. Upon introduction of iridium catalyst, a significant enhancement of the NO/HA ratio was observed. This observation indicates that the formation of NO via decomposition of HA is an important pathway in the catalytic decomposition of HAN.

  20. Effect of metal ions doping (M = Ti4+, Sn4+) on the catalytic performance of MnOx/CeO2 catalyst for low temperature selective catalytic reduction of NO with NH3

    Science.gov (United States)

    Xiong, Yan; Tang, Changjin; Dong, Lin

    2015-04-01

    Key Laboratory of Mesoscopic Chemistry of MOE, School of Chemistry and Chemical Engineering, Nanjing University, Nanjing 210093, PR China The abatement of nitrogen oxides (NOx) emission from exhaust gases of diesel and stationary sources is a significant challenge for economic and social development. Ceria-based solid solutions were synthesized and used as supports to prepare MnOx/Ce0.8Ti0.2O2 and MnOx/Ce0.8Sn0.2O2 catalysts (Mn/CeTi and Mn/CeSn) for low temperature selective catalytic reduction of NO by NH3 (NH3-SCR). The effects of Ti or Sn doping on the catalytic performance of MnOx/CeO2 catalyst were investigated. Experimental results show that doping of Ti or Sn increases the NO removal efficiency of MnOx/CeO2. The NO conversion of Mn/CeTi catalyst is more than 90 % at temperature window of 175 ~ 300 °C under a gas hour space velocity of 60,000 mL.g-1.h-1. Modified catalysts are also found to exhibit greatly improved resistance to sulfur-poisoning. NH3-TPD results suggest that NH3 desorption on the catalysts is observed over a wide temperature range, due to the variability of adsorbed NH3 species with different thermal stabilities. Doping of Ti and Sn into Mn/CeO2 greatly increased the NH3 adsorption ability of the composites which could promote the SCR reaction. Characterization results also indicate that doping of Ti or Sn brings about catalysts with higher BET surface area, enhanced oxygen storage capacity and increased surface acidity.

  1. In situ infrared study of catalytic decomposition of NO. Second semiannual report, 1996

    Energy Technology Data Exchange (ETDEWEB)

    Chuang, S.S.; Tan, Cher-Dip

    1997-04-01

    The growing concerns for the environment and increasingly stringent standards for NO emission have presented a major challenge to control NO emissions from electric utility plants and automobiles. Catalytic decomposition of NO is the most attractive approach for the control of NO emission for its simplicity. Successful development of an effective catalyst for NO decomposition will greatly decrease the equipment and operation cost of NO control. Due to lack of understanding of the mechanism of NO decomposition, efforts on the search of an effective catalyst have been unsuccessful. Scientific development of an effective catalyst requires fundamental understanding of the nature of active site, the rate-limiting step, and an approach to prolong the life of the catalyst. Research is proposed to study the reactivity of adsorbates for the direct NO decomposition and to investigate the feasibility of two novel approaches for improving catalyst activity and resistance to sintering. The first approach is the use of silanation to stabilize metal crystallites and supports for Cu-ZSM-5 and promoted Pt catalysts; the second is utilization of oxygen spillover and desorption to enhance NO decomposition activity. An innovative infrared reactor system will be used to observe and determine the dynamic behavior and the reactivity of adsorbates during NO decomposition, oxygen spillover, and silanation. A series of experiment including X-ray diffraction, temperature programmed desorption, temperature programmed reaction, X-ray photoelectron spectroscopy will be used to characterize the catalysts. The information obtained from this study will provide a scientific basis for developing an effective catalyst for the NO decomposition under practical flue gas conditions.

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2000-01-01

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

  3. 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...

  4. Understanding Catalytic Activity Trends for NO Decomposition and CO Oxidation using Density Functional Theory and Microkinetic Modeling

    DEFF Research Database (Denmark)

    Falsig, Hanne

    -relations between transition energies and adsorption energies. We establish a simple kinetic framework within the Sabatier analysis and obtain trends in catalytic activity based on the descriptors EO and ECO. We show that gold nanoparticles are optimal catalysts for low temperature CO oxidation and Pt closed packed...

  5. High catalytic activity of anatase titanium dioxide for decomposition of electrolyte solution in lithium ion battery

    Science.gov (United States)

    Liu, Ming; He, Yan-Bing; Lv, Wei; Zhang, Chen; Du, Hongda; Li, Baohua; Yang, Quan-Hong; Kang, Feiyu

    2014-12-01

    It has been indicated that anatase TiO2 is a promising anode material for lithium ion power battery from many previous researches. Whereas, in this work, we find that the anatase TiO2, when used as an anode for lithium ion battery, has high catalytic activity to initiate the decarboxylation reaction of electrolyte solution, resulting in the large generation of sole gaseous component, CO2. The ROLi species and the new phase of flake-like Li2TiF6 material are the main reaction products between anatase TiO2 and LiPF6 based electrolyte solution. This work provides important and urgent information that the surface chemistry of anatase TiO2 used as the anode material of lithium ion battery must be modified to suppress its catalytic activity for the decomposition of solvents.

  6. Methane catalytic decomposition over ordered mesoporous carbons: A promising route for hydrogen production

    Energy Technology Data Exchange (ETDEWEB)

    Botas, J.A.; Serrano, D.P. [Department of Chemical and Environmental Technology, ESCET, Rey Juan Carlos University, c/ Tulipan s/n, 28933 Mostoles, Madrid (Spain); IMDEA Energia, c/Tulipan s/n, 28933 Mostoles, Madrid (Spain); Guil-Lopez, R.; Pizarro, P.; Gomez, G. [Department of Chemical and Environmental Technology, ESCET, Rey Juan Carlos University, c/ Tulipan s/n, 28933 Mostoles, Madrid (Spain)

    2010-09-15

    Methane decomposition offers an interesting route for the CO{sub 2}-free hydrogen production. The use of carbon catalysts, in addition to lowering the reaction temperature, presents a number of advantages, such as low cost, possibility of operating under autocatalytic conditions and feasibility of using the produced carbons in non-energy applications. In this work, a novel class of carbonaceous materials, having an ordered mesoporous structure (CMK-3 and CMK-5), has been checked as catalysts for methane decomposition, the results obtained being compared to those corresponding to a carbon black sample (CB-bp) and two activated carbons, presenting micro- (AC-mic) and mesoporosity (AC-mes), respectively. Ordered mesoporous carbons, and especially CMK-5, possess a remarkable activity and stability for the hydrogen production through that reaction. Under both temperature programmed and isothermal experiments, CMK-5 has shown to be a superior catalyst for methane decomposition than the AC-mic and CB-bp materials. Likewise, the catalytic activity of CMK-5 is superior to that of AC-mes in spite of the presence of mesoporosity and a high surface area in the latter. The remarkable stability of the CMK-5 catalyst is demonstrated by the high amount of carbon deposits that can be formed on this sample. This result has been assigned to the growth of the carbon deposits from methane decomposition towards the outer part of the catalyst particles, avoiding the blockage of the uniform mesopores present in CMK-5. Thus, up to 25 g of carbon deposits have been formed per gram of CMK-5, while the latter still retains a significant catalytic activity. (author)

  7. Production of High Purity Multi-Walled Carbon Nanotubes from Catalytic Decomposition of Methane

    Institute of Scientific and Technical Information of China (English)

    Kong Bee Hong; Aidawati Azlin Binti Ismail; Mohamed Ezzaham Bin Mohd Mahayuddin; Abdul Rahman Mohamed; Sharif Hussein Sharif Zein

    2006-01-01

    Acid-based purification process of multi-walled carbon nanotubes (MWNTs) produced via catalytic decomposition of methane with NiO/TiO2 as a catalyst is described. By combining the oxidation in air and the acid refluxes, the impurities, such as amorphous carbon, carbon nanoparticles, and the NiO/TiO2 catalyst, are eliminated. Scanning electron microscopy (SEM) and transmission electron microscopy (TEM) images confirm the removal of the impurities. The percentage of the carbon nanotubes purity was analyzed using thermal gravimetric analysis (TGA). Using this process, 99.9 wt% purity of MWNTs was obtained.

  8. The mechanism of ammonium bisulfate formation and decomposition over V/WTi catalysts for NH3-selective catalytic reduction at various temperatures.

    Science.gov (United States)

    Li, Chenxu; Shen, Meiqing; Yu, Tie; Wang, Jianqiang; Wang, Jun; Zhai, Yanping

    2017-06-14

    In this study, the mechanism of ammonium bisulfate (ABS) formation and decomposition over V/WTi for the NH3-selective catalytic reduction (SCR) at various temperatures was deeply investigated. Bridged bidentate, chelating bidentate, and tridentate sulfates bound to TiO2 were formed as dominant intermediates at 200, 250, and 300 °C, respectively. These sulfates reacted with affinitive ammonium species to form ammonium (bi)sulfate species and also covered the active sites and embedded the VOSO4 intermediates, which resulted in an inferior intrinsic NH3-SCR conversion rate at 200 °C and 250 °C. At 300 °C, trace amounts of ABS on TiO2 presented no influence on the NH3-SCR performance. The electrons deviating towards sulfates through the bond between ABS and metal oxides (WO3 and TiO2) weakened the stability of ABS and lowered its decomposition temperature, whereas the vanadia species played the opposite role due to the sulfur species existing in an electron saturation state with the formation of the VOSO4 intermediate. The presence of NO + O2 could break the bonds inside ABS and it could react with the ammonium species originating from ABS, which pulls NH3 out of the ABS formation equilibrium and accelerates its decomposition and competitively inhibits its formation. Correspondingly, the faster NH3-SCR conversion rate and higher N2 selectivity improve the ABS poisoning resistance of the V/WTi catalyst at low temperatures.

  9. Effects of low-temperature catalytic pretreatments on coal structure and reactivity in liquefaction. Final technical report, Volume 2 - hydrogenative and hydrothermal pretreatments and spectroscopic characterization using pyrolysis-GC-MS, CPMAS {sup 13}C NMR and FT-IR

    Energy Technology Data Exchange (ETDEWEB)

    Chunshan Song; Hatcher, P.G.; Saini, A.K.; Wenzel, K.A.

    1998-01-01

    It has been indicated by DOE COLIRN panel that low-temperature catalytic pretreatment is a promising approach to the development of an improved liquefaction process. This work is a fundamental study on effects of pretreatments on coal structure and reactivity in liquefaction. The main objectives of this project are to study the coal structural changes induced by low-temperature catalytic and thermal pretreatments by using spectroscopic techniques; and to clarify the pretreatment-induced changes in reactivity or convertibility of coals. As the second volume of the final report, here we summarize our work on spectroscopic characterization of four raw coals including two subbituminous coals and two bituminous coals, tetrahydrofuran (THF)-extracted but unreacted coals, the coals (THF-insoluble parts) that have been thermally pretreated. in the absence of any solvents and in the presence of either a hydrogen-donor solvent or a non-donor solvent, and the coals (THF-insoluble parts) that have been catalytically pretreated in the presence of a dispersed Mo sulfide catalyst in the absence of any solvents and in the presence of either a hydrogen-donor solvent or a non-donor solvent.

  10. COMPARISON OF CATALYTIC ACTIVITIES BOTH FOR SELECTIVE OXIDATION AND DECOMPOSITION OF AMMONIA OVER Fe/HZβ CATALYST

    Directory of Open Access Journals (Sweden)

    YELİZ ÇETİN

    2016-11-01

    Full Text Available Ammonia is one of the syngas contaminants that must be removed before using the syngas downstream applications. The most promising hot-gas clean-up techniques of ammonia are selective catalytic oxidation (SCO and catalytic decomposition. In this study, the catalytic activities over Zeolite Hβ supported iron catalyst (Fe/HZβ were compared both for the two catalytic routes. For SCO experiments; temperature (300-550 °C, O2 (2000-6000 ppmv and (0-10% H2 concentrations were investigated with the presence of 800 ppm NH3 in each of the final gas mixture. In the second route, catalytic ammonia decomposition experiments were carried out with H2 in balance N2 (0-30% containing 800 ppm NH3 at 700°C and 800°C. In the SCO, NH3 conversions were increased with increasing reaction temperatures with the absence of H2 in the reaction mixture. With 10% H2, it was shown that NH3 conversions increased with decreasing the reaction temperature. This was interpreted as the competing H2 and NH3 oxidations over the catalyst. On the other hand, in the catalytic decomposition, thermodynamic equilibrium conversion of almost 100% was attained at both 700 and 800 °C. Upon H2 addition, all conversions decreased. The decrease in conversion seemed to be linear with inlet hydrogen concentration. Hydrogen was seen to inhibit ammonia decomposition reaction. It was shown that Fe/HZβ catalyst is better to use for catalytic decomposition of NH3 in syngas rather than SCO of NH3 in spite of higher reaction temperatures needed in the decomposition reaction.

  11. Catalytic Decomposition of Cellulose in Cooperative Ionic Liquids%复合离子液体中纤维素的催化分解

    Institute of Scientific and Technical Information of China (English)

    龙金星; 郭斌; 李雪辉; 王芙蓉; 王乐夫

    2011-01-01

    通过将酸性功能化离子液体与对纤维素具有溶解作用的离子液体进行复合,构建了一类新型的高效催化纤维素分解的体系,并采用热重(TG)分析方法,研究了复合离子液体中纤维素的分解行为.结果表明:复合离子液体中纤维素的分解温度明显降低,溶于离子液体中的纤维素可被酸性离子液体原位催化分解.纤维素的分解温度受离子液体催化剂的酸性及纤维素在复合离子液体中的溶解度影响明显:酸性越强,溶解度越大,纤维素的分解温度越低.%Cellulose, the abundant and cost-ineffective resource, is considered to be a perfect alternative for the alleviation of energy crisis and environmental pollution. However, most processes for the treatment of cellulose are rigor currently as it is insoluble in water and conventional organic solvents due to its strong intra and inter-molecular hydrogen bonds, where the phase problem hampers its utilization widely. Here, we built a novel and efficient cooperative ionic liquid pairs system for the low temperature catalytic conversion of cellulose, which was constructed through the combination of an acidic ionic liquid catalyst and a cellulose soluble ionic liquid solvent. The catalytic decomposition behavior of microcrystal cellulose in this vigorous catalytic system was studied intensively by thermogravimetry (TG). Results show that the decomposition temperature of cellulose decreases greatly in all cooperative ionic liquid pairs, cellulose dissolved in ionic liquid solvents can be in situ catalytic decomposed by acidic ionic liquids. Furthermore, the decomposition temperature is dependent on the acidic strength of the ionic liquid catalysts, stronger acidity results in a lower decomposition temperature of the cellulose. Moreover, we found that cellulose can be decomposed at lower temperature when the ionic liquid with higher solubility of cellulose is used.

  12. Porous MnOx for low-temperature NH3-SCR of NOx: the intrinsic relationship between surface physicochemical property and catalytic activity

    Science.gov (United States)

    Shi, Jian-Wen; Gao, Chen; Liu, Chang; Fan, Zhaoyang; Gao, Ge; Niu, Chunming

    2017-06-01

    Three kinds of porous MnOx catalysts consisted of nanoparticles (about 6.5, 8.5, and 21 nm, respectively) were successfully prepared by three different methods, co-precipitation method (CP), citric acid method (CA), and hydrothermal method (HT), respectively. Their physicochemical properties were characterized by TEM, XRD, BET, XPS, H2-TPR, and NH3-TPD in detail, and their catalytic activities were evaluated by the selective catalytic reduction (SCR) of NOx with NH3 in the temperature range of 60 300 °C. The results showed that their catalytic activities decreased in the order of MnOx/HT > MnOx/CA > MnOx/CP in the region of 60-120 °C due to the dominant factor resulted from the reducibility of MnOx. In contrast, their catalytic activities declined in the order of MnOx/CA > MnOx/HT > MnOx/CP in the region of 180-300 °C, which can be attributed to the amount of acid sites on the surface of these catalysts. In the region of 120-180 °C, the as-prepared three catalysts exhibited high catalytic activity with 100% NOx conversion under a high gas hourly space velocity (GHSV) of 36,000 h-1. [Figure not available: see fulltext.

  13. SO2 Poisoning Behaviors of Ca-Mn/TiO2 Catalysts for Selective Catalytic Reduction of NO with NH3 at Low Temperature

    OpenAIRE

    Qingqing Tian; Hongfeng Liu; Weiyuan Yao; Yan Wang; Yue Liu; Zhongbiao Wu; Haiqiang Wang; Xiaole Weng

    2014-01-01

    The sulfur tolerance of Ca modified MnOx /TiO2 catalysts in low-temperature SCR process was investigated. Experimental results revealed that the durability of developed catalysts in the presence of SO2 could be improved by Ca modification. After being subjected to a range of analytical techniques, it was found that the surface Ca species could act as a SO2 trap by preferentially reacting with SO2 to form bulk-like CaSO4, inhibiting the sulfation of active phase. Furthermore, the introducti...

  14. Influence of Preparation Conditions on the Catalytic Performance of MoNx/SBA-15 for Ammonia Decomposition

    Institute of Scientific and Technical Information of China (English)

    Hongchao Liu; Hua Wang; Jianghan Shen; Ying Sun; Zhongmin Liu

    2006-01-01

    The influence of preparation conditions (e.g. H2-N2 ratios, final nitriding temperatures) on the performance of MoNx/SBA-15 catalysts for ammonia decomposition was investigated. The variation of catalytic activity with H2-N2 ratios may be attributed to the variation of surface compositions and particle sizes of the active components. The variation of nitriding temperatures leads to the formation of molybdenum nitride domains of varying compositions, which are responsible for the difference in their catalytic performance with respect to ammonia decomposition. At 923 K, ammonia could be completely decomof ammonia.

  15. Influence of the addition of transition metals (Cr, Zr, Mo) on the properties of MnOx-FeOx catalysts for low-temperature selective catalytic reduction of NOx by Ammonia.

    Science.gov (United States)

    Zhou, Changcheng; Zhang, Yaping; Wang, Xiaolei; Xu, Haitao; Sun, Keqin; Shen, Kai

    2013-02-15

    The co-precipitation and citric acid methods were employed to prepare MnO(x)-FeO(x) catalysts for the low-temperature selective catalytic reduction (SCR) of NO(x) by ammonia. It was found that the Mn-Fe (CP) sample obtained from the co-precipitation method, which exhibited low crystalline of manganese oxides on the surface, high specific surface area and abundant acid sites at the surface, had better catalytic activity. The effects of doping different transition metals (Mo, Zr, Cr) in the Mn-Fe (CP) catalysts were further investigated. The study suggested that the addition of Cr can obviously reduce the take-off temperature of Mn-Fe catalyst to 90°C, while the impregnation of Zr and Mo raised that remarkably. The texture and micro-structure analysis revealed that for the Cr-doped Mn-Fe catalysts, the active components had better dispersion with less agglomeration and sintering and the largest BET surface specific area. In situ FTIR study indicated that the addition of Cr can increase significantly the surface acidity, especially, the Lewis acid sites, and promote the formation of the intermediate -NH(3)(+). H(2)-TPR results confirmed the better low-temperature redox properties of Mn-Fe-Cr.

  16. Application of microscopy technology in thermo-catalytic methane decomposition to hydrogen

    Energy Technology Data Exchange (ETDEWEB)

    Mei, Irene Lock Sow, E-mail: irene.sowmei@gmail.com; Lock, S. S. M., E-mail: serenelock168@gmail.com; Abdullah, Bawadi, E-mail: bawadi-abdullah@petronas.com.my [Chemical Engineering Department, Universiti Teknologi PETRONAS, Bandar Sri Iskandar, 31750, Perak (Malaysia)

    2015-07-22

    Hydrogen production from the direct thermo-catalytic decomposition of methane is a promising alternative for clean fuel production because it produces pure hydrogen without any CO{sub x} emissions. However, thermal decomposition of methane can hardly be of any practical and empirical interest in the industry unless highly efficient and effective catalysts, in terms of both specific activity and operational lifetime have been developed. In this work, bimetallic Ni-Pd on gamma alumina support have been developed for methane cracking process by using co-precipitation and incipient wetness impregnation method. The calcined catalysts were characterized to determine their morphologies and physico-chemical properties by using Brunauer-Emmett-Teller method, Field Emission Scanning Electron Microscopy, Energy-dispersive X-ray spectroscopy and Thermogravimetric Analysis. The results suggested that that the catalyst which is prepared by the co-precipitation method exhibits homogeneous morphology, higher surface area, have uniform nickel and palladium dispersion and higher thermal stability as compared to the catalyst which is prepared by wet impregnation method. This characteristics are significant to avoid deactivation of the catalysts due to sintering and carbon deposition during methane cracking process.

  17. Physico-Chemical Property and Catalytic Activity of a CeO2-Doped MnO(x)-TiO2 Catalyst with SO2 Resistance for Low-Temperature NH3-SCR of NO(x).

    Science.gov (United States)

    Shin, Byeongkil; Chun, Ho Hwan; Cha, Jin-Sun; Shin, Min-Chul; Lee, Heesoo

    2016-05-01

    The effects of CeO2 addition on the catalytic activity and the SO2 resistance of CeO2-doped MnO(x)-TiO2 catalysts were investigated for the low-temperature selective catalytic reduction (SCR) with NH3 of NO(x) emissions in marine applications. The most active catalyst was obtained from 30 wt% CeO2-MnO(x)-TiO2 catalyst in the whole temperature range of 100-300 degrees C at a low gas hourly space velocity (GHSV) of 10,000 h(-)1, and its de-NO(x) efficiency was higher than 90% over 250 degrees C. The enhanced catalytic activity may contribute to the dispersion state and catalytic acidity on the catalyst surface, and the highly dispersed Mn and Ce on the nano-scaled TiO2 catalyst affects the increase of Lewis and Brønsted acid sites. A CeO2-rich additive on MnO(x)-TiO2 could provide stronger catalytic acid sites, associated with NH3 adsorption and the SCR performance. As the results of sulfur resistance in flue gas that contains SO2, the de-NO(x) efficiency of MnO(x)-TiO2 decreased by 15% over 200 degrees C, whereas that of 30 wt% ceria-doped catalyst increased by 14-21% over 150 degrees C. The high SO2 resistance of CeO2-MnO(x)-TiO2 catalysts that resulted from the addition of ceria suppressed the formation of Mn sulfate species, which led to deactivation on the surface of nano-catalyst.

  18. Synthesis of CNTs/CuO and its catalytic performance on the thermal decomposition of ammonium perchlorate

    Directory of Open Access Journals (Sweden)

    Ping Cui

    2016-05-01

    Full Text Available Copper oxide (CuO nanoparticles were successfully deposited on carbon nanotubes’ (CNTs surface via complex-precipitation method, the nanocomposite was characterized by transmission electron microscopy (TEM, scanning electron microscopy (SEM, X-ray photoelectron spectroscopy (XPS, X-ray powder diffraction (XRD, Raman spectroscopy, Fourier transform infrared (FT-IR and Brunauer–Emmett–Teller (BET. The catalytic performance of CNTs/CuO on ammonium perchlorate (AP decomposition was analyzed by differential thermal analyzer (DTA, the DTA results showed its excellent catalytic effect on AP decomposition, as 8 wt.% CNTs/CuO was added in AP, the second exothermic peak temperature decreased by 158 °C. Such composite may be a promising candidate for catalyzing the AP thermal decomposition.

  19. The poisoning effect of PbO on Mn-Ce/TiO2 catalyst for selective catalytic reduction of NO with NH3 at low temperature

    Science.gov (United States)

    Zhou, Lingling; Li, Caiting; Zhao, Lingkui; Zeng, Guangming; Gao, Lei; Wang, Yan; Yu, Ming'e.

    2016-12-01

    Lead oxide (PbO) as one of the typical heavy metals in flue gas from power plants has strong accumulation as well as poisoning effects on SCR catalysts. In this paper, a series of PbO-doped Mn-Ce/TiO2 catalysts were synthesized by impregnation method. The poisoning effects of PbO over Mn-Ce/TiO2 samples for selective catalytic reduction of NO by NH3 were investigated based on catalytic activity test and characterizations. The NO conversion of Mn-Ce/TiO2 was greatly decreased after the addition of PbO. It was obvious that the NO conversion efficiency of Mn-Ce/TiO2 catalyst declined from 96.75% to about 40% at 200 °C when Pb:Mn molar ratio reached 0.5. Brunauer-Emmett-Teller (BET), X-ray diffraction (XRD), Scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS), Hydrogen temperature programmed reduction (H2-TPR), Ammonia temperature programmed desorption (NH3-TPD) and Fourier transform infrared spectroscopy (FT-IR) were carried out to study the deactivation reasons of PbO poisoned catalysts. Manganese oxides' crystallization, less reducible of manganese and cerium oxides, the decreasing of surface area, Mn4+ as well as Ce3+ concentration and chemisorbed oxygen (Ob) after the introduction of PbO, all of these resulted in a poor SCR performance. Furthermore, the alteration of acid sites (especially Brönsted acid sites), low ammonia adsorbance, an obvious reducing of ad-NOx species (only a spot of bidentate nitrates remained) and the vanishing of amide species contributed to the deactivation of Mn-Ce/TiO2 catalyst by PbO doping as well.

  20. Low-temperature gas from marine shales

    Directory of Open Access Journals (Sweden)

    Jarvie Daniel M

    2009-02-01

    Full Text Available Abstract Thermal cracking of kerogens and bitumens is widely accepted as the major source of natural gas (thermal gas. Decomposition is believed to occur at high temperatures, between 100 and 200°C in the subsurface and generally above 300°C in the laboratory. Although there are examples of gas deposits possibly generated at lower temperatures, and reports of gas generation over long periods of time at 100°C, robust gas generation below 100°C under ordinary laboratory conditions is unprecedented. Here we report gas generation under anoxic helium flow at temperatures 300° below thermal cracking temperatures. Gas is generated discontinuously, in distinct aperiodic episodes of near equal intensity. In one three-hour episode at 50°C, six percent of the hydrocarbons (kerogen & bitumen in a Mississippian marine shale decomposed to gas (C1–C5. The same shale generated 72% less gas with helium flow containing 10 ppm O2 and the two gases were compositionally distinct. In sequential isothermal heating cycles (~1 hour, nearly five times more gas was generated at 50°C (57.4 μg C1–C5/g rock than at 350°C by thermal cracking (12 μg C1–C5/g rock. The position that natural gas forms only at high temperatures over geologic time is based largely on pyrolysis experiments under oxic conditions and temperatures where low-temperature gas generation could be suppressed. Our results indicate two paths to gas, a high-temperature thermal path, and a low-temperature catalytic path proceeding 300° below the thermal path. It redefines the time-temperature dimensions of gas habitats and opens the possibility of gas generation at subsurface temperatures previously thought impossible.

  1. Combined effects Na and SO2 in flue gas on Mn-Ce/TiO2 catalyst for low temperature selective catalytic reduction of NO by NH3 simulated by Na2SO4 doping

    Science.gov (United States)

    Zhou, Aiyi; Yu, Danqing; Yang, Liu; Sheng, Zhongyi

    2016-08-01

    A series of Mn-Ce/TiO2 catalysts were synthesized through an impregnation method and used for low temperature selective catalytic reduction (SCR) of NOx with ammonia (NH3). Na2SO4 was added into the catalyst to simulate the combined effects of alkali metal and SO2 in the flue gas. Experimental results showed that Na2SO4 had strong and fluctuant influence on the activity of Mn-Ce/TiO2, because the effect of Na2SO4 included pore occlusion and sulfation effect simultaneously. When Na2SO4 loading content increased from 0 to 1 wt.%, the SCR activities of Na2SO4-doped catalysts decreased greatly. With further increasing amount of Na2SO4, however, the catalytic activity increased gradually. XRD results showed that Na2SO4 doping could induce the crystallization of MnOx phases, which were also confirmed by TEM and SEM results. BET results showed that the surface areas decreased and a new bimodal mesoporous structure formed gradually with the increasing amount of Na2SO4. XPS results indicated that part of Ce4+ and Mn3+ were transferred to Ce3+ and Mn4+ due to the sulfation after Na2SO4 deposition on the surface of the catalysts. When the doped amounts of Na2SO4 increased, NH3-TPD results showed that the Lewis acid sites decreased and the Brønsted acid sites of Mn-Ce/TiO2 increased quickly, which could be considered as another reason for the observed changes in the catalytic activity. The decreased Mn and Ce atomic concentration, the changes of their oxidative states, and the variation in acidic properties on the surface of Na2SO4-doped catalysts could be the reasons for the fluctuant changes of the catalytic activity.

  2. Low-temperature selective catalytic reduction of NO on CeO2-CuO/Al2O3 catalysts prepared by different methods.

    Science.gov (United States)

    Guo, Rui-Tang; Zhen, Wen-Long; Pan, Wei-Guo; Hong, Jie-Nan; Jin, Qiang; Ding, Cheng-Gang; Guo, Shi-Yi

    2014-08-01

    CeO2-CuO/Al2O3 catalysts were prepared by three different methods and their activities for selective catalytic reduction (SCR) of NO with NH3 were investigated. As can be seen from the experimental results, the catalyst prepared by the single-step sol-gel (SG) method showed the best SCR activity and resistance to SO2 and H2O. In order to investigate the relationship between the preparation method and the performance of SCR catalysts, the catalysts were characterized by using Brunauer-Emmett-Teller, X-ray diffraction, temperature programmed reduction with hydrogen, temperature programmed desorption with ammonia, X-ray photoelectron spectroscopy, Fourier transform infrared and thermo-gravimetric analysis techniques. It was found that the excellent performance of CeO2-CuO/Al2O3 catalyst prepared by the single-step SG method should be resulted from its large surface area, low crystallinity, high oxygen storage capacity, high NH3 adsorption capacity, high concentration of surface chemisorbed oxygen, weak sulphation process and weak water absorption.

  3. The poisoning effect of potassium ions doped on MnOx/TiO2 catalysts for low-temperature selective catalytic reduction

    Science.gov (United States)

    Zhang, Liangjing; Cui, Suping; Guo, Hongxia; Ma, Xiaoyu; Luo, Xiaogen

    2015-11-01

    The poisoning of alkali metal on MnOx/TiO2 catalysts used for selective catalytic reduction (SCR) of NOx by NH3 was investigated. KNO3, KCl and K2SO4 were doped on MnOx/TiO2 catalysts by sol-gel method, respectively. The SCR activity of each catalyst was measured for the removal of NOx with NH3 in the temperature range 90-330 °C. The experimental results showed that catalyst with KNO3 have a stronger deactivation effect than other catalysts. The properties of the catalysts were characterized by XRD, BET, SEM, XPS, H2-TPR, NH3-TPD and in situ DRIFTS analyses. The characterized results indicated that KNO3, KCl and K2SO4 caused the similar decrease of specific surface area and pore volume, but the quantity of acid sites for KNO3-MnOx/TiO2 catalyst reduced sharply. The main reason for catalyst deactivation is attributed to two aspects: one was physical influences for the decrease of surface area and pore volume, another was chemical influences that the K+ ions decomposed by KNO3 neutralized Brønsted acid sites of catalyst and reduced their reducibility. The chemical influence played a leading role on the deactivation of catalysts.

  4. Promoted V2O5/TiO2 catalysts for selective catalytic reduction of NO with NH3 at low temperatures

    DEFF Research Database (Denmark)

    Putluru, Siva Sankar Reddy; Schill, Leonhard; Godiksen, Anita;

    2016-01-01

    characterized by N2 physisorption, XRPD, NH3-TPD, H2-TPR, Raman, FTIR and EPR spectroscopy to investigate the properties of the catalysts. XRPD, Raman and FTIR showed that promotion with 15 wt.% HPA does not cause V2O5 to be present in crystalline form, also at a loading of 5 wt.% V2O5. Hence, use of HPAs does...... not cause increased N2O formation or unselective oxidation of NH3. NH3-TPD showed that promotion by HPA instead of WO3 causes the catalysts to possess a higher number of acid sites, both in fresh and alkali poisoned form, which might explain their higher potassium tolerance. Ex-situ EPR spectroscopy......The influence of varying the V2O5 content (3–6 wt.%) was studied for the selective catalytic reduction (SCR) of nitrogen oxides by ammonia on heteropoly acid (HPA)- and tungsten oxide (WO3)-promoted V2O5/TiO2 catalysts. The SCR activity and alkali deactivation resistance of HPA-promoted V2O5/TiO2...

  5. Mesoporous Silica Supported Pd-MnOx Catalysts with Excellent Catalytic Activity in Room-Temperature Formic Acid Decomposition

    Science.gov (United States)

    Jin, Min-Ho; Oh, Duckkyu; Park, Ju-Hyoung; Lee, Chun-Boo; Lee, Sung-Wook; Park, Jong-Soo; Lee, Kwan-Young; Lee, Dong-Wook

    2016-01-01

    For the application of formic acid as a liquid organic hydrogen carrier, development of efficient catalysts for dehydrogenation of formic acid is a challenging topic, and most studies have so far focused on the composition of metals and supports, the size effect of metal nanoparticles, and surface chemistry of supports. Another influential factor is highly desired to overcome the current limitation of heterogeneous catalysis for formic acid decomposition. Here, we first investigated the effect of support pore structure on formic acid decomposition performance at room temperature by using mesoporous silica materials with different pore structures such as KIE-6, MCM-41, and SBA-15, and achieved the excellent catalytic activity (TOF: 593 h−1) by only controlling the pore structure of mesoporous silica supports. In addition, we demonstrated that 3D interconnected pore structure of mesoporous silica supports is more favorable to the mass transfer than 2D cylindrical mesopore structure, and the better mass transfer provides higher catalytic activity in formic acid decomposition. If the pore morphology of catalytic supports such as 3D wormhole or 2D cylinder is identical, large pore size combined with high pore volume is a crucial factor to achieve high catalytic performance. PMID:27666280

  6. Catalytic Ammonia Decomposition over High-Performance Ru/Graphene Nanocomposites for Efficient COx-Free Hydrogen Production

    Directory of Open Access Journals (Sweden)

    Gang Li

    2017-01-01

    Full Text Available Highly-dispersed Ru nanoparticles were grown on graphene nanosheets by simultaneously reducing graphene oxide and Ru ions using ethylene glycol (EG, and the resultant Ru/graphene nanocomposites were applied as a catalyst to ammonia decomposition for COx-free hydrogen production. Tuning the microstructures of Ru/graphene nanocomposites was easily accomplished in terms of Ru particle size, morphology, and loading by adjusting the preparation conditions. This was the key to excellent catalytic activity, because ammonia decomposition over Ru catalysts is structure-sensitive. Our results demonstrated that Ru/graphene prepared using water as a co-solvent greatly enhanced the catalytic performance for ammonia decomposition, due to the significantly improved nano architectures of the composites. The long-term stability of Ru/graphene catalysts was evaluated for COx-free hydrogen production from ammonia at high temperatures, and the structural evolution of the catalysts was investigated during the catalytic reactions. Although there were no obvious changes in the catalytic activities at 450 °C over a duration of 80 h, an aggregation of the Ru nanoparticles was still observed in the nanocomposites, which was ascribed mainly to a sintering effect. However, the performance of the Ru/graphene catalyst was decreased gradually at 500 °C within 20 h, which was ascribed mainly to both the effect of the methanation of the graphene nanosheet under a H2 atmosphere and to enhanced sintering under high temperatures.

  7. Mesoporous Silica Supported Pd-MnOx Catalysts with Excellent Catalytic Activity in Room-Temperature Formic Acid Decomposition

    Science.gov (United States)

    Jin, Min-Ho; Oh, Duckkyu; Park, Ju-Hyoung; Lee, Chun-Boo; Lee, Sung-Wook; Park, Jong-Soo; Lee, Kwan-Young; Lee, Dong-Wook

    2016-09-01

    For the application of formic acid as a liquid organic hydrogen carrier, development of efficient catalysts for dehydrogenation of formic acid is a challenging topic, and most studies have so far focused on the composition of metals and supports, the size effect of metal nanoparticles, and surface chemistry of supports. Another influential factor is highly desired to overcome the current limitation of heterogeneous catalysis for formic acid decomposition. Here, we first investigated the effect of support pore structure on formic acid decomposition performance at room temperature by using mesoporous silica materials with different pore structures such as KIE-6, MCM-41, and SBA-15, and achieved the excellent catalytic activity (TOF: 593 h-1) by only controlling the pore structure of mesoporous silica supports. In addition, we demonstrated that 3D interconnected pore structure of mesoporous silica supports is more favorable to the mass transfer than 2D cylindrical mesopore structure, and the better mass transfer provides higher catalytic activity in formic acid decomposition. If the pore morphology of catalytic supports such as 3D wormhole or 2D cylinder is identical, large pore size combined with high pore volume is a crucial factor to achieve high catalytic performance.

  8. EFFECT OF MAGNETIC FIELD ON THE CATALYTIC DECOMPOSITION OF H2O2 BY Fe3O4

    OpenAIRE

    Tapia-Huanambal, N.; Facultad de Química e Ingeniería Química Departamento de Fisicoquímica,Universidad Nacional mayor de San Marcos,Lima,Perú.; Kuo, Ch.; Departamento de Química de la Universidad Estatal de Arizona, Templo, AZ 85287-1604. EE.UU.; Lajavardi, M.; Departamento de Química de la Universidad Estatal de Arizona, Templo, AZ 85287-1604. EE.UU.; Lin, Sh.; Departamento de Química de la Universidad Estatal de Arizona, Templo, AZ 85287-1604. EE.UU.

    2014-01-01

    The decomposition of hydrogen peroxide H2O2, is a simple reaction to study the effect of the magnetic field in chemical reactivity. Hydrogen peroxide when dissolved in water is decomposed into oxygen and water slowly. In the absence of a catalyst, the reaction is extremely slow. We have studied the effect of the magnetic field in the synthesis of Fe3O4 and catalytic decomposition of H2O2 by Fe3O4 also propose a theoretical treatment of the magnetic field effect on chemical reactions. The resu...

  9. 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.

  10. 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.

  11. Examination of surface phenomena of V₂O₅ loaded on new nanostructured TiO₂ prepared by chemical vapor condensation for enhanced NH₃-based selective catalytic reduction (SCR) at low temperatures.

    Science.gov (United States)

    Cha, Woojoon; Yun, Seong-Taek; Jurng, Jongsoo

    2014-09-01

    In this article, we describe the investigation and surface characterization of a chemical vapor condensation (CVC)-TiO2 support material used in a V2O5/TiO2 catalyst for enhanced selective catalytic reduction (SCR) activity and confirm the mechanism of surface reactions. On the basis of previous studies and comparison with a commercial TiO2 catalyst, we examine four fundamental questions: first, the reason for increased surface V(4+) ion concentrations; second, the origin of the increase in surface acid sites; third, a basis for synergistic influences on improvements in SCR activity; and fourth, a reason for improved catalytic activity at low reaction temperatures. In this study, we have cited the result of SCR with NH3 activity for removing NOx and analyzed data using the reported result and data from previous studies on V2O5/CVC-TiO2 for the SCR catalyst. In order to determine the properties of suitable CVC-TiO2 surfaces for efficient SCR catalysis at low temperatures, CVC-TiO2 specimens were prepared and characterized using techniques such as XRD, BET, HR-TEM, XPS, FT-IR, NH3-TPD, photoluminescence (PL) spectroscopy, H2-TPR, and cyclic voltammetry. The results obtained for the CVC-TiO2 materials were also compared with those of commercial TiO2.

  12. Co-production of hydrogen and carbon nanotubes on nickel foam via methane catalytic decomposition

    Science.gov (United States)

    Ping, Dan; Wang, Chaoxian; Dong, Xinfa; Dong, Yingchao

    2016-04-01

    The co-production of COx-free hydrogen and carbon nanotubes (CNTs) was achieved on 3-dimensional (3D) macroporous nickel foam (NF) via methane catalytic decomposition (MCD) over nano-Ni catalysts using chemical vapor deposition (CVD) technique. By a simple coating of a NiO-Al2O3 binary mixture sol followed by a drying-calcination-reduction treatment, NF supported composite catalysts (denoted as NiyAlOx/NF) with Al2O3 transition-layer incorporated with well-dispersed nano-Ni catalysts were successfully prepared. The effects of Ni loading, calcination temperature and reaction temperature on the performance for simultaneous production of COx-free hydrogen and CNTs were investigated in detail. Catalysts before and after MCD were characterized by XRD, TPR, SEM, TEM, TG and Raman spectroscopy technology. Results show that increasing Ni loading, lowering calcination temperature and optimizing MCD reaction temperature resulted in high production efficiency of COx-free H2 and carbon, but broader diameter distribution of CNTs. Through detailed parameter optimization, the catalyst with a Ni/Al molar ratio of 0.1, calcination temperature of 550 °C and MCD temperature of 650 °C was favorable to simultaneously produce COx-free hydrogen with a growth rate as high as 10.3% and CNTs with uniform size on NF.

  13. Study on the catalytic effect of NiO nanoparticles on the thermal decomposition of TEGDN/NC propellant.

    Science.gov (United States)

    Wei, Wenxian; Jiang, Xiaohong; Lu, Lude; Yang, Xujie; Wang, Xin

    2009-09-15

    The catalytic effect of NiO nanoparticles on the thermal decomposition of double-base propellant composed of nitrocellulose (NC) and triethylene glycol dinitrate (TEGDN) has been investigated by thermogravimetry-mass spectrometry (TG-MS) coupling technique. It was shown that adding 2% of NiO nanoparticles to TEGDN/NC propellant can accelerate the thermal decomposition process after around 188 degrees C TG-MS analysis indicated that NiO nanoparticles have resulted in the increase in intensity (peak area) of m/z=27, 28, and 29 MS signals, but the decrease in the intensity of m/z=18, 30, 44 and 46 (peak 2) MS signals during the thermal decompsition. The catalytic mechanism was also discussed in this paper.

  14. 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

  15. Fabrication of ammonium perchlorate/copper-chromium oxides core-shell nanocomposites for catalytic thermal decomposition of ammonium perchlorate

    Energy Technology Data Exchange (ETDEWEB)

    Eslami, Abbas, E-mail: eslami@umz.ac.ir [Department of Inorganic Chemistry, Faculty of Chemistry, University of Mazandaran, P.O.Box 47416-95447, Babolsar (Iran, Islamic Republic of); Juibari, Nafise Modanlou [Department of Inorganic Chemistry, Faculty of Chemistry, University of Mazandaran, P.O.Box 47416-95447, Babolsar (Iran, Islamic Republic of); Hosseini, Seyed Ghorban [Department of Chemistry, Malek Ashtar University of Technology, P.O. Box 16765-3454, Tehran (Iran, Islamic Republic of)

    2016-09-15

    The ammonium perchlorate/Cu(II)-Cr(III)-oxides(AP/Cu-Cr-O) core-shell nanocomposites were in-situ prepared by deposition of copper and chromium oxides on suspended ammonium perchlorate particles in ethyl acetate as solvent. The results of differential scanning calorimetery (DSC) and thermal gravimetric analysis (TGA) experiments showed that the nanocomposites have excellent catalytic effect on the thermal decomposition of AP, so that the released heat increases up to about 3-fold over initial values, changing from 450 J/g for pure AP to 1510 J/g for most appropriate mixture. For better comparison, single metal oxide/AP core-shell nanocomposite have also been prepared and the results showed that they have less catalytic effect respect to mixed metal oxides system. Scanning electron microscopy (SEM) results revealed homogenous deposition of nanoparticles on the surface of AP and fabrication of core-shell structures. The kinetic parameters of thermal decomposition of both pure AP and AP/Cu-Cr-O samples have been calculated by Kissinger method and the results showed that the values of pre-exponential factor and activation energy are higher for AP/Cu-Cr-O nanocomposite. The better catalytic effect of Cu-Cr-O nanocomposites is probably attributed to the synergistic effect between Cu{sup 2+} and Cr{sup 3+} in the nanocomposites, smaller particle size and more crystal defect. - Highlights: • The Cu-Cr-O nanoparticles were synthesized by chemical liquid deposition method. • Then, the AP/Cu-Cr-O core-shell nanocomposites were prepared. • The core-shell samples showed high catalytic activity for AP decomposition. • Thermal decomposition of samples occurs at lower temperature range.

  16. Synthesis of chrysalis-like CuO nanocrystals and their catalytic activity in the thermal decomposition of ammonium perchlorate

    Indian Academy of Sciences (India)

    Jun Wang; Shanshan He; Zhanshuang Li; Xiaoyan Jing; Milin Zhang; Zhaohua Jiang

    2009-11-01

    Chrysalis-like morphologies of CuO have been synthesized in large-quantity via a simple chemical deposition method without the use of any complex instruments and reagents. CuO nanocrystals showed a different morphology at three different temperatures, 25, 60 and 100°C. The particle size, morphology and crystal structure of the samples were characterized by transmission electron microscopy (TEM), scanning electron microscopy (SEM), X-ray diffraction (XRD) and Raman spectra. The catalytic effect of CuO nanoparticles on the decomposition of ammonium perchlorate (AP) was investigated by STA 409 PC thermal analyzer at a heating rate of 10°C min-1 from 35 to 500°C. Compared with the thermal decomposition of pure AP, the addition of CuO nanoparticles decreased the decomposition temperature of AP by about 85°C.

  17. Ti or Sn doping as a way to increase activity and sulfur tolerance of Mn/CeO2 catalyst for low temperature NH3 selective catalytic reduction of NO

    Science.gov (United States)

    Xiong, Yan; Tang, Changjin; Dong, Lin

    2015-04-01

    Mn/CeO2 catalysts modified by doping of Ti or Sn were investigated for low temperature selective catalytic reduction (SCR) of NO by NH3 with the aim of studying the effects of Ti, Sn doping on the catalytic performance. Ceria-based solid solutions (Ce0.8Ti0.2O2 and Ce0.8Sn0.2O2) were synthesized via inverse co-precipitation, and used as supports to prepare MnOx/Ce0.8M0.2O2 (M =Ti4+, Sn4+) catalysts through wetness impregnation method. The results showed that doping of Ti or Sn to the CeO2 support increase the NO removal efficiency. A NO conversion of more than 90 % was obtained over the Mn/CeTi catalyst at the temperature window of 175 ~ 300 °C under a gas hourly space velocity (GHSV) of 60,000 mL•g-1•h-1. Catalysts modified by Ti and Sn were also found to obtain higher SO2 resistance than Mn/CeO2 catalyst. More than 90% NO conversion and 95% N2 selectivity could be provided by Mn/CeTi catalyst in the presence of 100 ppm SO2 at 250 °C for 10 h. A series of characterization techniques, namely XRD, BET, H2-TPR, XPS, NH3-TPD and in situ DRIFTS were used to elucidate the structure and surface properties of the obtained supports and catalysts. The results indicate that doping of Ti or Sn brings about catalysts with favorable properties such as higher BET surface area, better oxygen storage capacity and stronger surface acidity. The relative amount of Mn4+, Ce3+, adsorbed oxygen species and oxygen vacancies on the surface of catalysts are in the order of Mn/CeTi>Mn/CeSn>Mn/CeO2, which is thought to make positive a contribution to the low-temperature SCR activity. The promoted SCR activity is considered as well to be related to the dual redox cycles in Mn/CeTi (Mn4+ + Ce3+ ↔ Mn3+ + Ce4+, Ce4+ + Ti3+ ↔ Ce3+ + Ti4+) and Mn/CeSn (Mn4+ + Ce3+ ↔ Mn3+ + Ce4+, Ce4+ + Sn2+ ↔ Ce3+ + Sn4+ ) catalysts.

  18. Effects of low-temperature catalytic pretreatments on coal structure and reactivity in liquefaction. Final technical report, Volume 1 - effects of solvents, catalysts and temperature conditions on conversion and structural changes of low-rank coals

    Energy Technology Data Exchange (ETDEWEB)

    Huang, Lili [Pennsylvania State Univ., University Park, PA (United States); Schobert, Harold H. [Pennsylvania State Univ., University Park, PA (United States); Song, Chunshan [Pennsylvania State Univ., University Park, PA (United States)

    1998-01-01

    The main objectives of this project were to study the effects of low-temperature pretreatments on coal structure and their impacts on subsequent liquefaction. The effects of pretreatment temperatures, catalyst type, coal rank, and influence of solvent were examined. Specific objectives were to identify the basic changes in coal structure induced by catalytic and thermal pretreatments, and to determine the reactivity of the catalytically and thermally treated coals for liquefaction. In the original project management plan it was indicated that six coals would be used for the study. These were to include two each of bituminous, subbituminous, and lignite rank. For convenience in executing the experimental work, two parallel efforts were conducted. The first involved the two lignites and one subbituminous coal; and the second, the two bituminous coals and the remaining subbituminous coal. This Volume presents the results of the first portion of the work, studies on two lignites and one subbituminous coal. The remaining work accomplished under this project will be described and discussed in Volume 2 of this report. The objective of this portion of the project was to determine and compare the effects of solvents, catalysts and reaction conditions on coal liquefaction. Specifically, the improvements of reaction conversion, product distribution, as well as the structural changes in the coals and coal-derived products were examined. This study targeted at promoting hydrogenation of the coal-derived radicals, generated during thermal cleavage of chemical bonds, by using a good hydrogen donor-solvent and an effective catalyst. Attempts were also made in efforts to match the formation and hydrogenation of the free radicals and thus to prevent retrogressive reaction.

  19. Preparation and catalytic activities for H{sub 2}O{sub 2} decomposition of Rh/Au bimetallic nanoparticles

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Haijun, E-mail: zhanghaijun@wust.edu.cn [Key Laboratory of Integrated Exploitation of Bayan Obo Multi-Metal Resources, Inner Mongolia University of Science and Technology, Baotou 014010 (China); The State Key Laboratory of Refractory and Metallurgy, Wuhan University of Science and Technology, Wuhan 430081 (China); Deng, Xiangong; Jiao, Chengpeng; Lu, Lilin; Zhang, Shaowei [The State Key Laboratory of Refractory and Metallurgy, Wuhan University of Science and Technology, Wuhan 430081 (China)

    2016-07-15

    Graphical abstract: PVP-protected Rh/Au bimetallic nanoparticles (BNPs) were prepared by using hydrogen sacrificial reduction method, the activity of Rh80Au20 BNPs were about 3.6 times higher than that of Rh NPs. - Highlights: • Rh/Au bimetallic nanoparticles (BNPs) of 3∼5 nm in diameter were prepared. • Activity for H{sub 2}O{sub 2} decomposition of BNPs is 3.6 times higher than that of Rh NPs. • The high activity of BNPs was caused by the existence of charged Rh atoms. • The apparent activation energy for H{sub 2}O{sub 2} decomposition over the BNPs was calculated. - Abstract: PVP-protected Rh/Au bimetallic nanoparticles (BNPs) were prepared by using hydrogen sacrificial reduction method and characterized by UV–vis, XRD, FT-IR, XPS, TEM, HR-TEM and DF-STEM, the effects of composition on their particle sizes and catalytic activities for H{sub 2}O{sub 2} decomposition were also studied. The as-prepared Rh/Au BNPs possessed a high catalytic activity for the H{sub 2}O{sub 2} decomposition, and the activity of the Rh{sub 80}Au{sub 20} BNPs with average size of 2.7 nm were about 3.6 times higher than that of Rh monometallic nanoparticles (MNPs) even the Rh MNPs possess a smaller particle size of 1.7 nm. In contrast, Au MNPs with size of 2.7 nm show no any activity. Density functional theory (DFT) calculation as well as XPS results showed that charged Rh and Au atoms formed via electronic charge transfer effects could be responsible for the high catalytic activity of the BNPs.

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

    Directory of Open Access Journals (Sweden)

    Irene Lock Sow Mei

    2016-08-01

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

  1. High-energy coordination polymers (CPs) exhibiting good catalytic effect on the thermal decomposition of ammonium dinitramide

    Science.gov (United States)

    Li, Xin; Han, Jing; Zhang, Sheng; Zhai, Lianjie; Wang, Bozhou; Yang, Qi; Wei, Qing; Xie, Gang; Chen, Sanping; Gao, Shengli

    2017-09-01

    High-energy coordination polymers (CPs) not only exhibit good energetic performances but also have a good catalytic effect on the thermal decomposition of energetic materials. In this contribution, two high-energy CPs Cu2(DNBT)2(CH3OH)(H2O)3·3H2O (1) and [Cu3(DDT)2(H2O)2]n (2) (H2DNBT = 3,3‧-dinitro-5,5‧-bis(1H-1,2,4-triazole and H3DDT = 4,5-bis(1H-tetrazol-5-yl)-2H-1,2,3-triazole) were synthesized and structurally characterized. Furthermore, 1 was thermos-dehydrated to produce Cu2(DNBT)2(CH3OH)(H2O)3 (1a). The thermal decomposition kinetics of 1, 1a and 2 were studied by Kissinger's method and Ozawa's method. Thermal analyses and sensitivity tests show that all compounds exhibit high thermal stability and low sensitivity for external stimuli. Meanwhile, all compounds have large positive enthalpy of formation, which are calculated as being (1067.67 ± 2.62) kJ mol-1 (1), (1464.12 ± 3.12) kJ mol-1 (1a) and (3877.82 ± 2.75) kJ mol-1 (2), respectively. The catalytic effects of 1a and 2 on the thermal decomposition of ammonium dinitramide (ADN) were also investigated.

  2. 浮石催化水中臭氧分解研究%Catalytic ozone aqueous decomposition promoted by pumice

    Institute of Scientific and Technical Information of China (English)

    袁磊; 沈吉敏; 陈忠林

    2012-01-01

    To investigate the influences of pumice chemical surface properties on catalytic ozonation,the decomposition rate of ozone in water was measured over pumice and the mechanism of ozone catalytic decomposition was discussed.The results showed that the pseudo-first order rate of ozone decomposition increased by 37.4 % for pumice catalysts.When t-BuOH was added,the rate constant decreased by 45.2 % for pumice catalysts,suggesting that the decomposition of ozone followed the mechanism of hydroxyl radical(·OH).The removal of ozone increased with the increasing of surface hydroxyl groups.High initial pH presented a positive effect in the ozone alone and ozone/pumice system.The pumice surface at nearly zero charged point was favorable for the decomposition of ozone in aqueous solution.Ozone aqueous decomposition in the presence of pumice takes place mainly on the natural material surface.The presence of metal oxides in pumice might catalyse ozone decomposition into more active radicals.%为考察浮石表面化学性质对水中臭氧分解的影响,测定了浮石催化水中臭氧分解的速率常数并探讨催化臭氧分解的途径.结果表明:浮石促进水中臭氧一级分解速率常数提高了37.4%;利用叔丁醇捕获生成的羟基自由基,催化臭氧分解速率常数降低了45.2%,浮石催化臭氧分解生成了羟基自由基;浮石表面羟基密度与催化臭氧分解率成正相关;随着溶液初始pH值增大,单独臭氧分解和浮石催化臭氧分解率均增加;由浮石pHpzc决定的表面电荷状态与催化臭氧分解效果有关,表面接近电中性时对催化臭氧分解有利.水中臭氧分解主要发生在浮石表面,浮石表面的金属氧化物可能是催化水中臭氧分解的活性物质。

  3. Wax: A benign hydrogen-storage material that rapidly releases H2-rich gases through microwave-assisted catalytic decomposition.

    Science.gov (United States)

    Gonzalez-Cortes, S; Slocombe, D R; Xiao, T; Aldawsari, A; Yao, B; Kuznetsov, V L; Liberti, E; Kirkland, A I; Alkinani, M S; Al-Megren, H A; Thomas, J M; Edwards, P P

    2016-10-19

    Hydrogen is often described as the fuel of the future, especially for application in hydrogen powered fuel-cell vehicles (HFCV's). However, its widespread implementation in this role has been thwarted by the lack of a lightweight, safe, on-board hydrogen storage material. Here we show that benign, readily-available hydrocarbon wax is capable of rapidly releasing large amounts of hydrogen through microwave-assisted catalytic decomposition. This discovery offers a new material and system for safe and efficient hydrogen storage and could facilitate its application in a HFCV. Importantly, hydrogen storage materials made of wax can be manufactured through completely sustainable processes utilizing biomass or other renewable feedstocks.

  4. Pt supported on carbon nanofibers as electrocatalyst for low temperature polymer electrolyte membrane fuel cells

    Energy Technology Data Exchange (ETDEWEB)

    Alcaide, Francisco; Alvarez, Garbine; Miguel, Oscar [Dpto. de Energia, CIDETEC, Paseo Miramon, 196, 20009 Donostia/San Sebastian (Spain); Lazaro, Maria Jesus; Moliner, Rafael [Instituto de Carboquimica, CSIC, Miguel Luesma Castan 4, 50018 Zaragoza (Spain); Lopez-Cudero, Ana; Solla-Gullon, Jose; Herrero, Enrique; Aldaz, Antonio [Instituto de Electroquimica, Universidad de Alicante, Apdo. 99, E-03080 Alicante (Spain)

    2009-05-15

    Carbon nanofibers synthesized via the thermo catalytic decomposition of methane were investigated for the first time as an electrocatalyst support in PEMFC cathodes. Their textural and physical properties make them a highly efficient catalyst support for cathodic oxygen reduction in low temperature PEMFC. Tests performed in MEAs showed that Pt supported on carbon nanofibers exhibited an enhancement of ca. 94% in power density at 0.600 V, in comparison with a commercial catalyst supported on conventional carbon black, Pt/Vulcan XC-72R. (author)

  5. Catalytic hydrogen peroxide decomposition on La1-xSrxCo03-d perovskite oxides

    NARCIS (Netherlands)

    Dam, Van-Ahn. T.; Olthuis, W.; Bergveld, P.; Berg, van den A.

    2005-01-01

    Lanthanide perovskite oxides are mentioned as material for hydrogen peroxide sensor because they can catalytically decompose hydrogen peroxide in an aqueous medium. The catalytic properties of these perovskite oxides to hydrogen peroxide are suggested due to their oxygen vacancies influenced by the

  6. Low-temperature selective catalytic reduction of NO with NH(3) over Mn-Ce oxides supported on TiO2 and Al2O3: a comparative study.

    Science.gov (United States)

    Jin, Ruiben; Liu, Yue; Wu, Zhongbiao; Wang, Haiqiang; Gu, Tingting

    2010-02-01

    MnCe oxides were supported on TiO(2) and Al(2)O(3) by an ultrasonic impregnation method and used for selective catalytic reduction (SCR) of NO with NH(3) at low-temperature (80-220 degrees C). MnCe/TiO(2) showed a relatively higher SCR activity than MnCe/Al(2)O(3) at the temperature range of 80-150 degrees C. When the reaction temperature was higher than 150 degrees C, MnCe/Al(2)O(3) exhibited superior SCR activity to MnCe/TiO(2). NH(3) temperature programmed desorption study proved that MnCe/TiO(2) was mainly Lewis acidic, while MnCe/Al(2)O(3) could provide more Brönsted acid sites. These acid sites play an important role in SCR according to in situ diffuse reflectance infrared transform spectroscopy (DRIFT) analysis. The main SCR reaction was a typical Eley-Rideal mechanism on MnCe/TiO(2), which took place between coordinated NH(3)/NH(4)(+) and gas-phase NO. For MnCe/Al(2)O(3), the reaction mainly occurred via another pathway when the temperature exceeded 150 degrees C, which commenced with the adsorption and oxidation of NO and was followed by reaction between NO(2) or NO(2)-containing compounds and NH(3) adspecies. This reaction pathway makes a significant contribution to the improved NO conversion for MnCe/Al(2)O(3) at higher temperature.

  7. 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.

  8. Reaction mechanism for the highly efficient catalytic decomposition of peroxynitrite by the amphipolar iron(III) corrole 1-Fe.

    Science.gov (United States)

    Avidan-Shlomovich, Shlomit; Gross, Zeev

    2015-07-21

    The amphipolar iron(III) corrole 1-Fe is one of the most efficient catalysts for the decomposition of peroxynitrite, the toxin involved in numerous diseases. This research focused on the mechanism of that reaction at physiological pH, where peroxynitrite is in equilibrium with its much more reactive conjugated acid, by focusing on the elementary steps involved in the catalytic cycle. Kinetic investigations uncovered the formation of a reaction intermediate in a process that is complete within a few milliseconds (k1 ∼ 3 × 10(7) M(-1) s(-1) at 5 °C, about 7 orders of magnitude larger than the first order rate constant for the non-catalyzed process). Multiple evidence points towards iron-catalyzed homolytic O-O bond cleavage to form nitrogen dioxide and hydroxo- or oxo-iron(iv) corrole. The iron(iv) intermediate was found to decay via multiple pathways that proceed at similar rates (k2 about 10(6) M(-1) s(-1)): reaction with nitrogen dioxide to form nitrate, nitration of the corrole macrocyclic, and dimerization to binuclear iron(iv) corrole. Catalysis in the presence of substrates affects the decay of the iron intermediate by either oxidative nitration (phenolic substrates) or reduction (ascorbate). A large enough excess of ascorbate accelerates the catalytic decomposition of PN by 1-Fe by orders of magnitude, prevents other decay routes of the iron intermediate, and eliminates nitration products as well. This suggests that the beneficial effect of the iron corrole under the reducing conditions present in most biological media might be even larger than in the purely chemical system. The acquired mechanistic insight is of prime importance for the design of optimally acting catalysts for the fast and safe decomposition of reactive oxygen and nitrogen species.

  9. Solid state green synthesis and catalytic activity of CuO nanorods in thermal decomposition of potassium periodate

    Science.gov (United States)

    Patel, Vinay Kumar; Bhattacharya, Shantanu

    2017-09-01

    The present study reports a facile solid state green synthesis process using the leaf extracts of Hibiscus rosa-sinensis to synthesize CuO nanorods with average diameters of 15–20 nm and lengths up to 100 nm. The as-synthesized CuO nanorods were characterized by x-ray diffraction, Fourier transform infrared spectroscopy, transmission electron microscopy and selected area electron diffraction. The formation mechanism of CuO nanorods has been explained by involving the individual role of amide I (amino groups) and carboxylate groups under excess hydroxyl ions released from NaOH. The catalytic activity of CuO nanorods in thermal decomposition of potassium periodate microparticles (µ-KIO4) microparticles was studied by thermo gravimetric analysis measurement. The original size (~100 µm) of commercially procured potassium periodate was reduced to microscale length scale to about one-tenth by PEG200 assisted emulsion process. The CuO nanorods prepared by solid state green route were found to catalyze the thermal decomposition of µ-KIO4 with a reduction of 18 °C in the final thermal decomposition temperature of potassium periodate.

  10. 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).

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

    Institute of Scientific and Technical Information of China (English)

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

    2012-01-01

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

  12. Synthesis, Characterization and Catalytic Properties of Attapulgite/CeO2 Nanocomposite Films for Decomposition of Rhodamine B.

    Science.gov (United States)

    Lu, Xiaowang; Li, Xiazhang; Qian, Junchao; Chen, Feng; Chen, Zhigang

    2015-08-01

    ATP(attapulgite)/CeO2 nanocomposite films were prepared on the glass substrates via a sol-gel and dip-coating route. The ATP/CeO2 nanocomposite films were characterized by Powder X-ray diffraction (PXRD), scanning electron microscopy (SEM), energy-dispersive spectrometry (EDS), transmission electron microscopy (TEM), atomic force microscopy (AFM) and fourier transform infrared spectroscopy (FT-IR). The results showed that the ATP/CeO2 nanocomposite films were free from cracks and the nanoparticles were attached onto the surface of attapulgite. The ATP/CeO2 nanocomposite films displayed excellent catalytic activity for decomposition of Rhodamine B. The COD (chemical oxygen demand) removal rate of rhodamine B using ATP/CeO2 nanocomposite films as catalyst reached as high as 94% when the weight ratio of ATP to CeO2 was 2:1.

  13. Synthesis of Ru nanoparticles confined in magnesium oxide-modified mesoporous alumina and their enhanced catalytic performance during ammonia decomposition

    KAUST Repository

    Tan, Hua

    2012-09-01

    In this work, Ru nanoparticles confined in the channels of ordered mesoporous alumina (MA) and magnesium oxide-modified ordered MA are prepared for the first time via a two-solvent technique, combined with the amorphous citrate route. Structural characterizations reveal that uniform 2-3 nm Ru nanoparticles are highly dispersed in the blockage-free channels of mesoporous supports. The Ru nanoparticles confined in MA modified with 20% molar ratio magnesium oxide exhibited a high catalytic activity and stability during ammonia decomposition due to the optimized particle size, basic support, lack of chlorine, and confined space provided by the channels of the mesoporous supports. © 2012 Elsevier B.V. All rights reserved.

  14. Wax: A benign hydrogen-storage material that rapidly releases H2-rich gases through microwave-assisted catalytic decomposition

    Science.gov (United States)

    Gonzalez-Cortes, S.; Slocombe, D. R.; Xiao, T.; Aldawsari, A.; Yao, B.; Kuznetsov, V. L.; Liberti, E.; Kirkland, A. I.; Alkinani, M. S.; Al-Megren, H. A.; Thomas, J. M.; Edwards, P. P.

    2016-01-01

    Hydrogen is often described as the fuel of the future, especially for application in hydrogen powered fuel-cell vehicles (HFCV’s). However, its widespread implementation in this role has been thwarted by the lack of a lightweight, safe, on-board hydrogen storage material. Here we show that benign, readily-available hydrocarbon wax is capable of rapidly releasing large amounts of hydrogen through microwave-assisted catalytic decomposition. This discovery offers a new material and system for safe and efficient hydrogen storage and could facilitate its application in a HFCV. Importantly, hydrogen storage materials made of wax can be manufactured through completely sustainable processes utilizing biomass or other renewable feedstocks. PMID:27759014

  15. Synthesis of polycrystalline Co{sub 3}O{sub 4} nanowires with excellent ammonium perchlorate catalytic decomposition property

    Energy Technology Data Exchange (ETDEWEB)

    Zhou, Hai [State Key Laboratory of Coal Conversion, Institute of Coal Chemistry, Chinese Academy of Sciences, Taiyuan 030001 (China); University of Chinese Academy of Sciences, Beijing 100049 (China); Lv, Baoliang, E-mail: lbl604@sxicc.ac.cn [State Key Laboratory of Coal Conversion, Institute of Coal Chemistry, Chinese Academy of Sciences, Taiyuan 030001 (China); Wu, Dong; Xu, Yao [State Key Laboratory of Coal Conversion, Institute of Coal Chemistry, Chinese Academy of Sciences, Taiyuan 030001 (China)

    2014-12-15

    Graphical abstract: Co{sub 3}O{sub 4} nanowires with excellent ammonium perchlorate catalytic decomposition property were synthesized via a methanamide-assisted hydrolysis and subsequent dissolution–recrystallization process in the presence of methanamide. - Abstract: Co{sub 3}O{sub 4} nanowires, with the length of tens of micrometers and the width of several hundred nanometers, were produced by a hydrothermal treatment and a post-anneal process. X-ray diffraction (XRD) result showed that the Co{sub 3}O{sub 4} nanowires belong to cubic crystal system. Scanning electron microscopy (SEM) and high-resolution transmission electron microscopy (HRTEM) analysis indicated that the Co{sub 3}O{sub 4} nanowires, composed by single crystalline nanoparticles, were of polycrystalline nature. On the basis of time-dependent experiments, methanamide-assisted hydrolysis and subsequent dissolution–recrystallization process were used to explain the precursors' formation process of the polycrystalline Co{sub 3}O{sub 4} nanowires. The TGA experiments showed that the as-obtained Co{sub 3}O{sub 4} nanowires can catalyze the thermal decomposition of ammonium perchlorate (AP) effectively.

  16. Catalytic decomposition of tar derived from wood waste pyrolysis using Indonesian low grade iron ore as catalyst

    Energy Technology Data Exchange (ETDEWEB)

    Wicakso, Doni Rahmat [Chemical Engineering Department, Faculty of Engineering, Lambung Mangkurat University, Jalan A. Yani KM. 36 Banjarbaru, 70714, South Kalimantan (Indonesia); Chemical Engineering Department, Faculty of Engineering, Gadjah Mada University, Jalan Grafika No. 2 Bulaksumur, Yogyakarta, 55281 (Indonesia); Sutijan; Rochmadi [Chemical Engineering Department, Faculty of Engineering, Gadjah Mada University, Jalan Grafika No. 2 Bulaksumur, Yogyakarta, 55281 (Indonesia); Budiman, Arief, E-mail: abudiman@ugm.ac.id [Chemical Engineering Department, Faculty of Engineering, Gadjah Mada University, Jalan Grafika No. 2 Bulaksumur, Yogyakarta, 55281 (Indonesia); Center for Energy Studies, Gadjah Mada University, Sekip K1A, Yogyakarta, 55281 (Indonesia)

    2016-06-03

    Low grade iron ore can be used as an alternative catalyst for bio-tar decomposition. Compared to other catalysts, such as Ni, Rd, Ru, Pd and Pt, iron ore is cheaper. The objective of this research was to investigate the effect of using low grade iron ore as catalyst for tar catalytic decomposition in fixed bed reactor. Tar used in this experiment was pyrolysis product of wood waste while the catalyst was Indonesian low grade iron ore. The variables studied were temperatures between 500 – 600 °C and catalyst weight between 0 – 40 gram. The first step, tar was evaporated at 450 °C to produce tar vapor. Then, tar vapor was flowed to fixed bed reactor filled low grade iron ore. Gas and tar vapor from reactor was cooled, then the liquid and uncondensable gas were analyzed by GC/MS. The catalyst, after experiment, was weighed to calculate total carbon deposited into catalyst pores. The results showed that the tar components that were heavy and light hydrocarbon were decomposed and cracked within the iron ore pores to from gases, light hydrocarbon (bio-oil) and carbon, thus decreasing content tar in bio-oil and increasing the total gas product. In conclusion, the more low grade iron ore used as catalyst, the tar content in the liquid decrease, the H{sup 2} productivity increased and calorimetric value of bio-oil increased.

  17. Catalytic decomposition of tar derived from wood waste pyrolysis using Indonesian low grade iron ore as catalyst

    Science.gov (United States)

    Wicakso, Doni Rahmat; Sutijan, Rochmadi, Budiman, Arief

    2016-06-01

    Low grade iron ore can be used as an alternative catalyst for bio-tar decomposition. Compared to other catalysts, such as Ni, Rd, Ru, Pd and Pt, iron ore is cheaper. The objective of this research was to investigate the effect of using low grade iron ore as catalyst for tar catalytic decomposition in fixed bed reactor. Tar used in this experiment was pyrolysis product of wood waste while the catalyst was Indonesian low grade iron ore. The variables studied were temperatures between 500 - 600 °C and catalyst weight between 0 - 40 gram. The first step, tar was evaporated at 450 °C to produce tar vapor. Then, tar vapor was flowed to fixed bed reactor filled low grade iron ore. Gas and tar vapor from reactor was cooled, then the liquid and uncondensable gas were analyzed by GC/MS. The catalyst, after experiment, was weighed to calculate total carbon deposited into catalyst pores. The results showed that the tar components that were heavy and light hydrocarbon were decomposed and cracked within the iron ore pores to from gases, light hydrocarbon (bio-oil) and carbon, thus decreasing content tar in bio-oil and increasing the total gas product. In conclusion, the more low grade iron ore used as catalyst, the tar content in the liquid decrease, the H2 productivity increased and calorimetric value of bio-oil increased.

  18. Catalytic decomposition of methane to COx-free hydrogen and carbon nanotubes over Co–W/MgO catalysts

    Directory of Open Access Journals (Sweden)

    Ahmed E. Awadallah

    2015-09-01

    Full Text Available Bimetallic catalysts containing a series of Co/W at 40/10, 30/20, 20/30 and 10/40 wt% supported on MgO with a total metal content of 50 wt% were prepared and used for the catalytic decomposition of methane to COx-free hydrogen and multi-walled carbon nanotubes (MWCNTs. The solid fresh and exhausted catalysts were characterized structurally and chemically through XRD, TPR, BET, TGA, TEM and Raman spectroscopy. The 40%Co–10%W/MgO catalyst exhibited the highest activity for the production of both hydrogen and MWCNTs. The formation of a large amount of non-interacted Co3O4 species is considered as the main reason for the catalyst superiority in its activity. On the contrary, catalysts formulations of 20%Co–30%W and 10%Co–40%W demonstrated the formation of a large amount of hardly reducible CoWO4 and MgWO4 particles causing lower activity of these catalysts toward methane decomposition as evidenced through the XRD and TPR results.

  19. Photochemical fabrication of size-controllable gold nanoparticles on chitosan and their application on catalytic decomposition of acetaldehyde

    Energy Technology Data Exchange (ETDEWEB)

    Yu, Chung-Chin [Department of Environmental Engineering, Vanung University, 1, Van Nung Road, Shuei-Wei Li, Chung-Li City, Taiwan (China); Nano Materials Applications R and D Center, Vanung University, 1, Van Nung Road, Shuei-Wei Li, Chung-Li City, Taiwan (China); Yang, Kuang-Hsuan, E-mail: khy@mail.vnu.edu.tw [Department of Chemical and Materials Engineering, Vanung University, 1, Van Nung Road, Shuei-Wei Li, Chung-Li City, Taiwan (China); Nano Materials Applications R and D Center, Vanung University, 1, Van Nung Road, Shuei-Wei Li, Chung-Li City, Taiwan (China); Liu, Yu-Chuan [Department of Chemical and Materials Engineering, Vanung University, 1, Van Nung Road, Shuei-Wei Li, Chung-Li City, Taiwan (China); Nano Materials Applications R and D Center, Vanung University, 1, Van Nung Road, Shuei-Wei Li, Chung-Li City, Taiwan (China); Chen, Bo-Chuen [Department of Chemical and Materials Engineering, Vanung University, 1, Van Nung Road, Shuei-Wei Li, Chung-Li City, Taiwan (China)

    2010-07-15

    In this work, we report a new pathway to prepare size-controllable gold nanoparticles (NPs) on chitosan (Ch) in aqueous solutions for improving catalytic decomposition of acetaldehyde by pure gold NPs at room temperature. First, Au substrates were cycled in deoxygenated aqueous solutions containing 0.1N NaCl and 1 g/L Ch from -0.28 to +1.22 V vs Ag/AgCl at 500 mV/s for 200 scans. Then the solutions were irradiated with UV lights of different wavelengths to prepare size-controllable Au NPs on Ch. Experimental results indicate that the particle sizes of prepared NPs are increased when UV lights with longer wavelengths were employed. The particle sizes of resulted Au NPs can be controlled from 10 to 50 nm. Moreover, the decomposition of acetaldehydes in wines can be significantly enhanced by ca. 190% of magnitude due to the contribution of the adsorption of Au NPs on Ch.

  20. Pyrolysis of aseptic packages (tetrapak) in a laboratory screw type reactor and secondary thermal/catalytic tar decomposition.

    Science.gov (United States)

    Haydary, J; Susa, D; Dudáš, J

    2013-05-01

    Pyrolysis of aseptic packages (tetrapak cartons) in a laboratory apparatus using a flow screw type reactor and a secondary catalytic reactor for tar cracking was studied. The pyrolysis experiments were realized at temperatures ranging from 650 °C to 850 °C aimed at maximizing of the amount of the gas product and reducing its tar content. Distribution of tetrapak into the product yields at different conditions was obtained. The presence of H2, CO, CH4, CO2 and light hydrocarbons, HCx, in the gas product was observed. The Aluminum foil was easily separated from the solid product. The rest part of char was characterized by proximate and elemental analysis and calorimetric measurements. The total organic carbon in the tar product was estimated by elemental analysis of tars. Two types of catalysts (dolomite and red clay marked AFRC) were used for catalytic thermal tar decomposition. Three series of experiments (without catalyst in a secondary cracking reactor, with dolomite and with AFRC) at temperatures of 650, 700, 750, 800 and 850 °C were carried out. Both types of catalysts have significantly affected the content of tars and other components in pyrolytic gases. The effect of catalyst on the tetrapack distribution into the product yield on the composition of gas and on the total organic carbon in the tar product is presented in this work.

  1. Sol–gel method to prepare graphene/Fe{sub 2}O{sub 3} aerogel and its catalytic application for the thermal decomposition of ammonium perchlorate

    Energy Technology Data Exchange (ETDEWEB)

    Lan, Yuanfei; Li, Xiaoyu; Li, Guoping; Luo, Yunjun, E-mail: yjluo@bit.edu.cn [Beijing Institute of Technology, School of Materials Science and Engineering (China)

    2015-10-15

    Graphene/Fe{sub 2}O{sub 3} (Gr/Fe{sub 2}O{sub 3}) aerogel was synthesized by a simple sol–gel method and supercritical carbon dioxide drying technique. In this study, the morphology and structure were characterized by scanning electron microscopy, transmission electron microscopy, X-ray photoelectron spectroscopy, X-ray diffraction, and nitrogen sorption tests. The catalytic performance of the as-synthesized Gr/Fe{sub 2}O{sub 3} aerogel on the thermal decomposition of ammonium perchlorate (AP) was investigated by thermogravimetric and differential scanning calorimeter. The experimental results showed that Fe{sub 2}O{sub 3} with particle sizes in the nanometer range was anchored on the Gr sheets and Gr/Fe{sub 2}O{sub 3} aerogel exhibits promising catalytic effects for the thermal decomposition of AP. The decomposition temperature of AP was obviously decreased and the total heat release increased as well.

  2. 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.

  3. Catalytic decomposition of ammonia in a fuel gas at high temperature and pressure

    Energy Technology Data Exchange (ETDEWEB)

    Mojtahedi, W.; Abbasian, J. [Enviropower Inc., Espoo (Finland)

    1995-11-01

    In connection with the purification of fuel gas for gas turbines in the IGCC process to meet NO{sub x} standards and maintain the thermal efficiency of the process, tests were carried out with a 7.5 cm pressurized reactor to decompose ammonia at high temperature (700-900{degree}C) and pressure (2 MPa) using Ni-based catalysts. The effects of temperature, pressure, ammonia concentration and gas residence time were determined. The simulated coal gas composition was varied to allow assessment of the effect of contaminants (sulfur compounds and tars) on the ammonia decomposition efficiency of five catalysts under otherwise identical operating conditions. The results show that two of the catalysts tested are capable of efficiently reducing the concentration of ammonia in the gas. 12 refs., 13 figs.

  4. Conversion of KCl into KBH4 by Mechano-Chemical Reaction and its Catalytic Decomposition

    Science.gov (United States)

    Bilen, Murat; Gürü, Metin; Çakanyildirim, Çetin

    2017-07-01

    Production of KBH4, in the presence of KCl, B2O3 and MgH2 by means of a mechanical reaction and a dehydrogenation kinetic, constitute the main parts of this study. Operating time and reactant ratio are considered as two parameters for the mechanical reaction to obtain the maximum yield. The production process was carried out in a ball milling reactor, and the product residue was purified with ethylene diamine (EDA) and subsequently characterized by Fourier Transform Infrared Spectroscopy (FT-IR) and x-ray Diffraction (XRD) analyses. Optimum time for mechano-chemical treatment and reactant ratio (MgH2/KCl) were obtained as 1000 min and 1.0, respectively. Synthesized and commercial KBH4 were compared by hydrolysis tests in the presence of Co1-xNix/Al2O3 heterogeneous catalyst. Hydrogen generation rates, activation energy and order of the KBH4 decomposition reaction were obtained as 1578 {mL}_{{{{H}}2 }} \\min^{ - 1} {g}_{{catalyst}}^{ - 1}, 39.2 kJ mol-1 and zero order, respectively.

  5. Preparation of MnOx/TiO2 catalyst and catalytic performance for selective catalytic reduction of NO with NH3 at low temperature%MnOx/TiO2催化剂的制备及其低温NH3选择性催化还原NO性能

    Institute of Scientific and Technical Information of China (English)

    徐海涛; 金保昇; 张亚平; 孙克勤; 汪小蕾

    2012-01-01

    为了研究MnOx/TiO2催化剂的低温催化还原NO性能,采用微乳液法在不同的煅烧温度下制备了不同晶相的纳米TiO2,并以此为载体,利用浸渍法制备了一系列MnOx/TiO2催化剂.然后,利用BET,XRD,HRTEM,H2-TPR等方法研究了载体和催化剂的微观结构、分散状态和氧化还原性质.实验结果表明:随着煅烧温度的增加,纳米TiO2从锐钛型逐渐向金红石型转变,700℃煅烧得到的纳米TiO2呈混晶相,800℃煅烧得到的纳米TiO2则为纯金红石型;锐钛型及混晶相TiO2载体与活性氧化物MnOx之间的相互作用较为强烈,当纳米TiO2中金红石型与锐钛型并存时,MnOx优先与锐钛型纳米TiO2作用;纯金红石型纳米TiO2与MnOx之间的相互作用较弱.模拟NH3选择性催化还原NO的反应活性测试结果表明,500℃煅烧得到的MnOx/TiO2催化剂表现出较高的低温活性.%To study the MnOI/TiO2 catalyst's catalytic performance for selective catalytic reduction of NO with NH, at low temperature, TiO2 nanoparticles with different crystalline phases are prepared by the micro-emulsion method at different calcination temperatures. A series of MnO/TiOjare prepared by impregnation with TiO2 nanoparticles and manganous acetate precursor. Then the micro-structures , dispersion status and redox properties of the product are characterized by BET, X-ray diffraction, high-resolution transmission electron microscopy, and H2-temperature programmed reduction. The experimental results show that with the increase of the calcination temperature, the anatase TiO2 transfers to the rutile TiO2. When the calcination temperature is 700 ℃, the anatase-rutile mixture of TiO2 nanoparticles is formed; when the calcination temperature is 800 ℃, the pure rutile TiO2 occurs. The anatase TiO2 and the anatase-rutile mixtures have a stronger reaction with MnO, than the rutile TiO2. MnO, can react firstly with the anatase TiO2 and then with the rutile TiO2. The catalyst test

  6. 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.

  7. 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.

  8. Synthesis of carbon nanotubes by catalytic vapor decomposition (CVD) method: Optimization of various parameters for the maximum yield

    Indian Academy of Sciences (India)

    Kanchan M Samant; Santosh K Haram; Sudhir Kapoor

    2007-01-01

    This paper describes an effect of flow rate, carrier gas (H2, N2 and Ar) composition, and amount of benzene on the quality and the yield of carbon nanotubes (CNTs) formed by catalytical vapour decomposition (CVD) method. The flow and mass control of gases and precursor vapors respectively were found to be interdependent and therefore crucial in deciding the quality and yield of CNTs. We have achieved this by modified soap bubble flowmeter, which controlled the flow rates of two gases, simultaneously. With the help of this set-up, CNTs could be prepared in any common laboratory. Raman spectroscopy indicated the possibilities of formation of single-walled carbon nanotubes (SWNTs). From scanning electron microscopy (SEM) measurements, an average diameter of the tube/bundle was estimated to be about 70 nm. The elemental analysis using energy dispersion spectrum (EDS) suggested 96 at.wt.% carbon along with ca. 4 at.wt. % iron in the as-prepared sample. Maximum yield and best quality CNTs were obtained using H2 as the carrier gas.

  9. Low-temperature steam-reforming of ethanol over ZnO-supported Ni and Cu catalysts

    Energy Technology Data Exchange (ETDEWEB)

    Homs, Narcis; Llorca, Jordi; De la Piscina, Pilar Ramirez [Departament de Quimica Inorganica, Universitat de Barcelona, C/Marti i Franques 1-11, 08028 Barcelona (Spain)

    2006-08-15

    ZnO-supported Ni and Cu as well as bimetallic Co-Ni and Co-Cu catalysts containing ca. 0.7wt% sodium promoter and prepared by the co-precipitation method were tested in the ethanol steam-reforming reaction at low temperature (523-723K), using a bioethanol-like mixture diluted in Ar. Monometallic ZnO-supported Cu or Ni samples do not exhibit good catalytic performance in the steam-reforming of ethanol for hydrogen production. Copper catalyst mainly dehydrogenates ethanol to acetaldehyde, whereas nickel catalyst favours ethanol decomposition. However, the addition of Ni to ZnO-supported cobalt has a positive effect both on the production of hydrogen at low temperature (<573K), and on catalyst stability. Evidence for alloy formation as well as mixed oxides at the microstructural level was found in the bimetallic systems after running the ethanol steam-reforming reaction by HRTEM-EELS. (author)

  10. Performance and mechanism study for low-temperature SCR of NO with propylene in excess oxygen over Pt/TiO2 catalyst.

    Science.gov (United States)

    Zhang, Zhixiang; Chen, Mingxia; Jiang, Zhi; Shangguan, Wenfeng

    2010-01-01

    A 0.5 wt.% Pt/TiO2 catalyst was prepared and used for the low-temperature selective catalytic reduction (SCR) of NO with C3H6 in the presence of excess oxygen. The effects of Pt loading and O2 concentration on Pt/TiO2 catalytic performance for low-temperature SCR were investigated. It was found that optimal Pt loading was 0.5 wt.% and excess O2 favored low-temperature SCR of NOx. The mechanism of low-temperature SCR of NO with C3H6 was investigated with respect to the behavior of adsorbed species over Pt/TiO2 at 150 degrees C using in situ DRIFTS. The results indicated that surface nitrosyl species (Ptdelta(+)-NO and Ti3(+)-NO) and Pt2(+)-CO are main reaction intermediates during the interactions of NO, C3H6 and O2. A simplified NO decomposition mechanism for the low-temperature SCR of NO with C3H6 was proposed.

  11. Catalytic

    Directory of Open Access Journals (Sweden)

    S.A. Hanafi

    2014-03-01

    Full Text Available A series of dealuminated Y-zeolites impregnated by 0.5 wt% Pt catalysts promoted by different amounts of Ni, Pd or Cr (0.3 and 0.6 wt% were prepared and characterized as hydrocracking catalysts. The physicochemical and structural characterization of the solid catalysts were investigated and reported through N2 physisorption, XRD, TGA-DSC, FT-IR and TEM techniques. Solid catalysts surface acidities were investigated through FT-IR spectroscopy aided by pyridine adsorption. The solid catalytic activities were evaluated through hydroconversion of n-hexane and n-heptane employing micro-catalytic pulse technique directly connected to a gas chromatograph analyzer. The thermal stability of the solids was also investigated up to 800 °C. Crystallinity studies using the XRD technique of all modified samples proved analogous to the parent Y-zeolite, exhibiting nearly an amorphous and microcrystalline character of the second metal oxides. Disclosure of bimetallic catalysts crystalline characterization, through XRD, was not viable. The nitrogen adsorption–desorption isotherms for all samples concluded type I adsorption isotherms, without any hysteresis loop, indicating that the entire pore system is composed of micropores. TEM micrographs of the solid catalysts demonstrate well-dispersed Pt, Ni and Cr nanoparticles having sizes of 2–4 nm and 7–8 nm, respectively. The catalytic activity results indicate that the bimetallic (0.5Pt–0.3Cr/D18H–Y catalyst is the most active towards n-hexane and n-heptane isomerization while (0.5Pt–0.6Ni/D18H–Y catalyst can be designed as most suitable as a cracking catalyst.

  12. Catalytic decomposition of CH4 over Ni-Al2O3-SiO2 catalysts:Influence of pretreatment conditions for the production of H2

    Institute of Scientific and Technical Information of China (English)

    Jangam Ashok; Gangadhara Raju; Padigapati Shiva Reddy; Machiraju Subrahmanyam; Akula Venugopal

    2008-01-01

    This article reports the production of COx free hydrogen and carbon nanofibers by the catalytic decomposition of methane over Ni-Al2O3-SiO2 catalysts. The influence of reaction temperature, pretreatment temperature, and effect of reductive pretreatment on the decomposition of methane activity is investigated. The physico-chemical characteristics of fresh and deactivated samples were characterized using BET-SA, XRD, TPR, SEM/TEM, CHNS analyses and correlated with the methane decomposition results obtained. The Ni-Al-Si (4 : 0.5 : 1.5) catalyst reduced with hydrazine hydrate produced better H2 yields of ca. 1815 mol H2/mol Ni than the catalyst reduced with 5% H2/N2.

  13. Preparation of Nanometer ZnTiO_3 Powder and Its Catalytic Performance for Thermal Decomposition of Ammoniam Perchlorate%钛酸锌的制备及其对高氯酸铵热分解的催化性能

    Institute of Scientific and Technical Information of China (English)

    杨行浩; 张景林; 王作山

    2009-01-01

    @@ 从20世纪60年代开始.钛酸锌(ZnO-TiO_2)体系相图及特性的基础研究工作就开展起来了[1].钙钛矿型氧化物结构的ZnTiO_3及基于ZnTiO_3的一些ABO_3型陶瓷固溶体材料,由于在超导体、催化剂、微波介电陶瓷以及电磁材料等领域有着重要用途,近年来已引起越来越多的关注[2~9].%ZnTiO_3 nanocrystals were prepared by sol-gel method, using Zn(NO_3)_2 and Ti(C_4H_9O)_4 in the topic. The as-prepared ZnTiO_3 nanocrystals were characterized by XRD, FTIR and TEM, and the catalytic performance of ZnTiO_3 nanocrystals of different contents for the ammonium perchlorate (AP)decomposition was investigated by thermal analysis. The results indicate that ZnTiO_3 with pure cube structure can be synthesized at 600 ℃ by this procedure,which was spheroid with particle size of about 60~100 nm. The results expressed that the low temperature decomposition peaks of AP is advanced by 17 ℃ and the high temperature decomposition peaks of AP is advanced by 24 ℃ when adding 5% nanoparticle ZnTiO_3 powder. The catalytic effects of ZnTiO_3 powders on the high temperature decomposition of AP are less than that of nanometer metal powders, but all the micron metal powders decrease the low decomposition temperature of AP.

  14. Preparation of CoFeO Nanocrystallites by Solvothermal Process and Its Catalytic Activity on the Thermal Decomposition of Ammonium Perchlorate

    Directory of Open Access Journals (Sweden)

    Shusen Zhao

    2010-01-01

    Full Text Available Nanometer cobalt ferrite (CoFe2O4 was synthesized by polyol-medium solvothermal method and characterized by X-ray diffraction (XRD, transmission electron microscopy (TEM, and selected area electron diffraction (SAED. Further, the catalytic activity and kinetic parameters of CoFe2O4 nanocrystallites on the thermal decomposition behavior of ammonium perchlorate (AP have been investigated by thermogravimetry and differential scanning calorimetry analysis (TG-DSC. The results imply that the catalytic performance of CoFe2O4 nanocrystallites is significant and the decrease in the activation energy and the increase in the rate constant for AP further confirm the enhancement in catalytic activity of CoFe2O4 nanocrystallites. A mechanism based on an proton transfer process has also been proposed for AP in the presence of CoFe2O4 nanocrystallites.

  15. Heating a chemical current source which operates at low temperature

    Energy Technology Data Exchange (ETDEWEB)

    Mitsumata, T.; Khosikhara, N.

    1983-02-14

    A chamber for catalytic ignition of hydrogen or gasoline is installed in a chemical current source. The isolated heat heats the chemical current source with a low temperature of the environment providing its optimal operational conditions. The fuel is fed into the chamber from a tank or chamber located in the body of the chemical current source.

  16. Low-temperature (≤600 °C) growth of high-quality In x Ga1‑ x N (x ∼ 0.3) by metalorganic vapor phase epitaxy using NH3 decomposition catalyst

    Science.gov (United States)

    Yamamoto, Akio; Kodama, Kazuki; Matsuoka, Takashi; Kuzuhara, Masaaki

    2017-04-01

    In x Ga1‑ x N (x ∼ 0.3) films on GaN/sapphire templates were grown by NH3 decomposition catalyst-assisted metalorganic vapor phase epitaxy (CA-MOVPE). NiO-based pellets were used as a catalyst. Even at a temperature lower than 500 °C, single-crystal In0.3Ga0.7N films were grown without the incorporation of metallic components (In, Ga) or the cubic phase. In contrast with the case of InN growth using the same catalyst [A. Yamamoto et al., Jpn. J. Appl. Phys. 55, 05FD04 (2016)], no marked grain growth or hydrogen etching was observed in In0.3Ga0.7N. Samples grown at a temperature ≤500 °C showed a full-width at half-maximum of the (0002) X-ray rocking curve as small as 10 arcmin or smaller. The carrier concentration in nominally undoped In0.3Ga0.7N grown using the catalyst was higher by about 4 orders of magnitude than that in conventional MOVPE samples. Secondary ion mass spectroscopy analysis revealed that such a higher carrier concentration was due to the marked reduction in carbon contamination level in the films.

  17. 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.

  18. 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.

  19. 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.

  20. Catalytic decomposition of gaseous 1,2-dichlorobenzene over CuOx/TiO₂ and CuOx/TiO₂-CNTs catalysts: Mechanism and PCDD/Fs formation.

    Science.gov (United States)

    Wang, Qiu-lin; Huang, Qun-xing; Wu, Hui-fan; Lu, Sheng-yong; Wu, Hai-long; Li, Xiao-dong; Yan, Jian-hua

    2016-02-01

    Gaseous 1,2-dichlorobenzene (1,2-DCBz) was catalytically decomposed in a fixed-bed catalytic reactor using composite copper-based titanium oxide (CuOx/TiO2) catalysts with different copper ratios. Carbon nanotubes (CNTs) were introduced to produce novel CuOx/TiO2-CNTs catalysts by the sol-gel method. The catalytic performances of CuOx/TiO2 and CuOx/TiO2-CNTs on 1,2-DCBz oxidative destruction under different temperatures (150-350 °C) were experimentally examined and the correlation between catalyst structure and catalytic activity was characterized and the role of oxygen in catalytic reaction was discussed. Polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/Fs) generation during 1,2-DCBz catalytic oxidation by CuOx/TiO2-CNTs composite catalyst was also examined. Results indicate that the 1,2-DCBz destruction/removal efficiencies of CuOx (4 wt%)/TiO2 catalyst at 150 °C and 350 °C with a GHSV of 3400 h(-1) are 59% and 94% respectively and low-temperature (150 °C) catalytic activity of CuOx/TiO2 on 1,2-DCBz oxidation can be improved from 59 to 77% when CNTs are introduced. Furthermore, oxygen either in catalyst or from reaction atmosphere is indispensible in reaction. The former is offered to activate and oxidize the 1,2-DCBz adsorbed on catalyst, thus can be generally consumed during reaction and the oxygen content in catalyst is observed lost from 39.9 to 35.0 wt% after reacting under inert atmosphere; the latter may replenish the vacancy in catalyst created by the consumed oxygen thus extends the catalyst life and raises the destruction/removal efficiency. The introduction of CNTs also increases the Cu(2+)/Cu(+) ratio, chemisorbed oxygen concentration and surface lattice oxygen binding energy which are closely related with catalytic activity. PCDD/Fs is confirmed to be formed when 1,2-DCBz catalytically oxidized by CuOx/TiO2-CNTs composite catalyst with sufficient oxygen (21%), proper temperature (350 °C) and high concentration of 1,2-DCBz feed (120 ppm

  1. 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.

  2. Ozone decomposition

    Directory of Open Access Journals (Sweden)

    Batakliev Todor

    2014-06-01

    Full Text Available Catalytic ozone decomposition is of great significance because ozone is a toxic substance commonly found or generated in human environments (aircraft cabins, offices with photocopiers, laser printers, sterilizers. Considerable work has been done on ozone decomposition reported in the literature. This review provides a comprehensive summary of the literature, concentrating on analysis of the physico-chemical properties, synthesis and catalytic decomposition of ozone. This is supplemented by a review on kinetics and catalyst characterization which ties together the previously reported results. Noble metals and oxides of transition metals have been found to be the most active substances for ozone decomposition. The high price of precious metals stimulated the use of metal oxide catalysts and particularly the catalysts based on manganese oxide. It has been determined that the kinetics of ozone decomposition is of first order importance. A mechanism of the reaction of catalytic ozone decomposition is discussed, based on detailed spectroscopic investigations of the catalytic surface, showing the existence of peroxide and superoxide surface intermediates

  3. pH dependent catalytic activities of platinum nanoparticles with respect to the decomposition of hydrogen peroxide and scavenging of superoxide and singlet oxygen

    Science.gov (United States)

    Liu, Yi; Wu, Haohao; Li, Meng; Yin, Jun-Jie; Nie, Zhihong

    2014-09-01

    Recently, platinum (Pt) nanoparticles (NPs) have received increasing attention in the field of catalysis and medicine due to their excellent catalytic activity. To rationally design Pt NPs for these applications, it is crucial to understand the mechanisms underlying their catalytic and biological activities. This article describes a systematic study on the Pt NP-catalyzed decomposition of hydrogen peroxide (H2O2) and scavenging of superoxide (O2&z.rad;-) and singlet oxygen (1O2) over a physiologically relevant pH range of 1.12-10.96. We demonstrated that the catalytic activities of Pt NPs can be modulated by the pH value of the environment. Our results suggest that Pt NPs possess peroxidase-like activity of decomposing H2O2 into &z.rad;OH under acidic conditions, but catalase-like activity of producing H2O and O2 under neutral and alkaline conditions. In addition, Pt NPs exhibit significant superoxide dismutase-like activity of scavenging O2&z.rad;- under neutral conditions, but not under acidic conditions. The 1O2 scavenging ability of Pt NPs increases with the increase in the pH of the environment. The study will provide useful guidance for designing Pt NPs with desired catalytic and biological properties.Recently, platinum (Pt) nanoparticles (NPs) have received increasing attention in the field of catalysis and medicine due to their excellent catalytic activity. To rationally design Pt NPs for these applications, it is crucial to understand the mechanisms underlying their catalytic and biological activities. This article describes a systematic study on the Pt NP-catalyzed decomposition of hydrogen peroxide (H2O2) and scavenging of superoxide (O2&z.rad;-) and singlet oxygen (1O2) over a physiologically relevant pH range of 1.12-10.96. We demonstrated that the catalytic activities of Pt NPs can be modulated by the pH value of the environment. Our results suggest that Pt NPs possess peroxidase-like activity of decomposing H2O2 into &z.rad;OH under acidic conditions

  4. Hydrothermal preparation of Fe{sub 2}O{sub 3}/graphene nanocomposite and its enhanced catalytic activity on the thermal decomposition of ammonium perchlorate

    Energy Technology Data Exchange (ETDEWEB)

    Yuan, Yuan [National Special Superfine Powder Engineering Research Center, Nanjing University of Science and Technology, Nanjing 210094 (China); Jiang, Wei, E-mail: smallyuan1234@163.com [National Special Superfine Powder Engineering Research Center, Nanjing University of Science and Technology, Nanjing 210094 (China); Wang, Yujiao; Shen, Ping; Li, Fengsheng; Li, Pingyun [National Special Superfine Powder Engineering Research Center, Nanjing University of Science and Technology, Nanjing 210094 (China); Zhao, Fengqi; Gao, Hongxu [Xi’an Modern Chemistry Research Institute, Xi’an 710065 (China)

    2014-06-01

    Fe{sub 2}O{sub 3}/graphene nanocomposite was prepared by a facile hydrothermal method, during which graphene oxides (GOs) were reduced to graphene with hydrazine and Fe{sub 2}O{sub 3} nanoparticles were simultaneously anchored on graphene sheets. The morphology of the obtained Fe{sub 2}O{sub 3}/graphene nanocomposite was investigated by scanning electron microscopy (SEM) and transmission electron microscope (TEM). It was revealed by TEM images that Fe{sub 2}O{sub 3} nanoparticles grew well on the surfaces of graphene. As much as I know, this new nanocomposite has not been investigated as a catalyst on the thermal decomposition of AP yet. In this work, the catalytic performance of the synthesized material on the thermal decomposition of ammonium perchlorate (AP) was investigated creatively by differential scanning calorimetry (DSC). The results of DSC indicated that graphene obviously improved the catalytic activity of Fe{sub 2}O{sub 3} on the thermal decomposition of AP due to its high specific area.

  5. Pure CuCr2O4 nanoparticles: Synthesis, characterization and their morphological and size effects on the catalytic thermal decomposition of ammonium perchlorate

    Science.gov (United States)

    Hosseini, Seyed Ghorban; Abazari, Reza; Gavi, Azam

    2014-11-01

    In the present paper a pure phase of the copper chromite spinel nanoparticles (CuCr2O4 SNPs) were synthesized via the sol-gel route using citric acid as a complexing agent. Then, the CuCr2O4 SNPs has been characterized by field emission scanning electron microscope (FE-SEM), transmission electron microscopy (TEM), and X-ray diffraction (XRD). In the next step, with the addition of Cu-Cr-O nanoparticles (NPs), the effects of different parameters such as Cu-Cr-O particle size and the Cu/Cr molar ratios on the thermal behavior of Cu-Cr-O NPs + AP (ammonium perchlorate) mixtures were investigated. As such, the catalytic effect of the Cu-Cr-O NPs for thermal decomposition of AP was evaluated by thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC). TGA/DSC results showed that the samples with different morphologies exhibited different catalytic activity in different stages of thermal decomposition of AP. Also, in the presence of Cu-Cr-O nanocatalysts, all of the exothermic peaks of AP shifted to a lower temperature, indicating the thermal decomposition of AP was enhanced. Moreover, the heat released (ΔH) in the presence of Cu-Cr-O nanocatalysts was increased to 1490 J g-1.

  6. 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.

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

    Science.gov (United States)

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

    2016-12-01

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

  8. Purification of Carbon Nanotubes Synthesized by Catalytic Decomposition of Methane using Bimetallic Fe-Co Catalysts Supported on MgO

    Energy Technology Data Exchange (ETDEWEB)

    Guan, Beh Hoe; Ramli, Irmawati [Advanced Materials and Nanotechnology Laboratory, Institute of Advanced Technology, Universiti Putra Malaysia 43400 UPM Serdang, Selangor (Malaysia); Yahya, Noorhana [Fundamental and Applied Science Department Universiti Teknologi Petronas, Bandar Seri Iskandar, 31750 Tronoh, Perak (Malaysia); Pah, Lim Kean, E-mail: irmawati@science.upm.edu.my [Physics department, Faculty of Science, Universiti Putra Malaysia 43400 UPM Serdang, Selangor (Malaysia)

    2011-02-15

    This work reports the synthesis of carbon nanotubes by catalytic decomposition of methane using bimetallic Fe-Co catalysts supported on MgO. Transmission electron microscopy (TEM) results show the as-prepared carbon nanotubes are multi-walled carbon nanotubes (MWCNTs) with diameter in the range of 15nm to 45nm. Purification of as-prepared MWCNTs was carried out by acid and heat treatment method. EDX results show the Fe, Co and MgO catalysts were successfully removed by refluxing the as-prepared MWCNTs in 3M H{sub 2}SO{sub 4}.

  9. Purification of Carbon Nanotubes Synthesized by Catalytic Decomposition of Methane using Bimetallic Fe-Co Catalysts Supported on MgO

    Science.gov (United States)

    Guan, Beh Hoe; Ramli, Irmawati; Yahya, Noorhana; Kean Pah, Lim

    2011-02-01

    This work reports the synthesis of carbon nanotubes by catalytic decomposition of methane using bimetallic Fe-Co catalysts supported on MgO. Transmission electron microscopy (TEM) results show the as-prepared carbon nanotubes are multi-walled carbon nanotubes (MWCNTs) with diameter in the range of 15nm to 45nm. Purification of as-prepared MWCNTs was carried out by acid and heat treatment method. EDX results show the Fe, Co and MgO catalysts were successfully removed by refluxing the as-prepared MWCNTs in 3M H2SO4.

  10. 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.

  11. Preparation of Coaxial-Line and Hollow Mn2O3 Nanofibers by Single-Nozzle Electrospinning and Their Catalytic Performances for Thermal Decomposition of Ammonium Perchlorate.

    Science.gov (United States)

    Liang, Jiyuan; Yang, Jie; Cao, Weiguo; Guo, Xiangke; Guo, Xuefeng; Ding, Weiping

    2015-09-01

    Coaxial-line and hollow Mn2O3 nanofibers have been synthesized by a simple single-nozzle electrospinning method without using a complicated coaxial jet head, combined with final calcination. The crystal structure and morphology of the Mn2O3 nanofibers were investigated by using the X-ray diffraction, scanning electron microscopy and transmission electron microscopy. The results indicate that the electrospinning distance has important influence on the morphology and structure of the obtained Mn2O3 nanofibers, which changes from hollow fibers for short electrospinning distance to coaxial-line structure for long electrospinning distance after calcination in the air. The formation mechanisms of different structured Mn2O3 fibers are discussed in detail. This facile and effective method is easy to scale up and may be versatile for constructing coaxial-line and hollow fibers of other metal oxides. The catalytic activity of the obtained Mn2O3 nanofibers on thermal decomposition of ammonium perchlorate (AP) was studied by differential scanning calorimetry (DSC). The results show that the hollow Mn2O3 nanofibers have good catalytic activity to promote the thermal decomposition of AP.

  12. MOF-derived hollow NiO-ZnO composite micropolyhedra and their application in catalytic thermal decomposition of ammonium perchlorate

    Science.gov (United States)

    Yang, Ji-Min

    2017-07-01

    Ni(II)-doped Zn-based coordination polymer particles (Ni(II)-doped Zn-CPPs) with controllable shape and size were successfully synthesized by solvothermal method, which further transformed to porous ZnO-NiO composite micropolyhedra without significant alterations in shape by calcination in air. Those products were characterized by powder X-ray diffraction (XRD), field emission scanning electron microscopy (SEM), transmission electron microscopy (TEM), thermogravimetric analysis (TGA), infrared spectroscopy (IR) and gas adsorption measurements. The catalytic activity of ZnO-NiO composites for the thermal decomposition of ammonium perchlorate (AP) was investigated. The result shows that all ZnO-NiO composites efficiently catalyzed the thermal decomposition of AP, and NiO-ZnO composite hollow octahedrons have the highest catalytic efficiency compared with that of most materials reported to now, indicating that porous ZnO-NiO composite micropolyhedra could be a promising candidate material for application in AP-based propellant.

  13. Ex situ synthesis of G/$\\alpha$-Fe$_2$O$_3$ nanocomposite and its catalytic effect on the thermal decomposition of ammonium perchlorate

    Indian Academy of Sciences (India)

    MERIEM AMINA FERTASSI; QI LIU; RUNZE LI; PINGAN LIU; JINGYUAN LIU; RONG-RONG CHEN; LIANHE LIU; JUN WANG

    2017-08-01

    $\\alpha$-Fe$_2$O$_3$ nanoparticles were prepared by a facile hydrothermal method using ferric chloride hexahydrate(FeCl$_3$·6H$_2$O) as a precursor. Graphene oxide (GO) was synthesized using a modified Hummers method and graphenenanosheets (G) were successfully obtained by thermal reduction of GO. G/$\\alpha$-Fe$_2$O$_3$ nanocomposite was prepared using ex situ synthesis in the presence of $\\alpha$-Fe$_2$O$_3$ nanoparticles and GO solution. The characterization of the as-prepared materialswas performed using X-ray diffraction analyses and Fourier transform infrared spectroscopy; their morphology wasinvestigated by scanning electron microscopy and transmission electron microscopy; the specific surface area (SBET) wasdetermined by nitrogen adsorption; their catalytic activity on the thermal decomposition of ammonium perchlorate (AP) wasinvestigated by differential thermal analysis (DTA). The results of DTA indicated that the obtained nanomaterials contributein ameliorating the thermal decomposition of AP; specifically, the high decomposition temperature of AP decreases from432 to 380$^{\\circ}$C. A significant decrease in the activation energy was also achieved in the presence of these nanomaterials, and the mixture of ammonium perchlorate with G/$\\alpha$-Fe$_2$O$_3$ showed the lowest value (from 129 to 80.33 kJ mol$^{−1}$).

  14. 催化分解臭氧的方法及催化剂性能概述%Review of Ozone Catalytic Decomposition

    Institute of Scientific and Technical Information of China (English)

    傅嘉媛; 冯易君; 钟兵; 杨庆良

    2001-01-01

    臭氧作为一种有毒物质广泛存在于人们生活环境中,当 其浓度超过0.06mg/m3时,对人体就有害了。因此对臭氧的分解十分必要。本文介绍了多 种分解臭氧的方法,并着重介绍催化分解法。对各种臭氧分解催化剂的组成、制备方法及活 性作一综述。%Ozone is a toxic substance commonly found or gener a ted in human environments.When its concentration is up to 0.06mg/m3,it is d angerous to people.So ozone decomposition is necessary.This review provides man y methods of ozone decomposition,mainly provides catalytic ozone decomposition including catalyst composition,catalyst preparation,and performance.

  15. Synthesis of Co Nanoparticles and Their Catalytic Effect on the Decomposition of Ammonium Perchlorate%纳米金属钴粒子的制备及对高氯酸铵热分解的影响

    Institute of Scientific and Technical Information of China (English)

    段红珍; 蔺向阳; 刘冠鹏; 徐磊; 李凤生

    2008-01-01

    The monodispersed Co nanoparticles were successfully prepared by means of hydrogen plasma method in inert atmosphere. The particle size, specific surface area, crystal structure and morphology of the samples were characterized by transmission electron microscopy (TEM), BET equation, X-ray diffraction (XRD), and the corre- sponding selected area electron diffraction (SAED). The catalytic effect of Co nanoparticles on the decomposition of ammonium perchlorate (AP) was investigated by differential thermal analyzer (DTA). Compared with the ther- mal decomposition of pure AP, the addition of Co nanoparticles (2%-10%, by mass) decreases the decomposition temperature of AP by 145.01-155.72℃. Compared with Co3O4 nanoparticles and microsized Co particles, the catalytic effect of Co nanoparticles for AP is stronger. Such effect is attributed to the large specific surface area and its interaction of Co with decomposition intermediate gases. The present work provides useful information for the application of Co nanoparticles in the AP-based propellant.

  16. 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.

  17. 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.

  18. A comparative study of Mn/CeO2, Mn/ZrO2 and Mn/Ce-ZrO2 for low temperature selective catalytic reduction of NO with NH3 in the presence of SO2 and H2O.

    Science.gov (United States)

    Shen, Boxiong; Zhang, Xiaopeng; Ma, Hongqing; Yao, Yan; Liu, Ting

    2013-04-01

    Ce-ZrO2 is a widely used three-way catalyst support. Because of the large surface area and excellent redox quality, Ce-ZrO2 may have potential application in selective catalytic reduction (SCR) systems. In the present work, Ce-ZrO2 was introduced into a low-temperature SCR system and CeO2 and ZrO2 supports were also introduced to make a contrastive study. Mn/CeO2, Mn/ZrO2 and Mn/Ce-ZrO2 were prepared by impregnating these supports with Mn(NO3)2 solution, and have been characterized by N2-BET, XRD, TPR, TPD, XPS, FT-IR and TG. The activity and resistance to SO2 and H2O of the catalysts were investigated. Mn/Ce-ZrO2 and Mn/CeO2 were proved to have better low-temperature activities than Mn/ZrO2, and yielded 98.6% and 96.8% NO conversion at 180 degrees C, respectively. This is mainly because Mn/Ce-ZrO2 and Mn/CeO2 had higher dispersion of manganese oxides, better redox properties and more weakly adsorbed oxygen species than Mn/ZrO2. In addition, Mn/Ce-ZrO2 showed a good resistance to SO2 and H2O and presented 87.1% NO conversion, even under SO2 and H2O treatment for 6 hours, and the activity of Mn/Ce-ZrO2 was almost restored to its original level after cutting off the injection of SO2 and H2O. This was due to the weak water absorption and weak sulfation process on the surface of the catalyst.

  19. Ferrocene Covalently Functionalized Graphene Oxide: Preparation,Characterization and Catalytic Performance for Thermal Decomposition of Ammonium Perchlorate%二茂铁功能化石墨烯氧化物的制备、表征及对高氯酸铵热分解的催化性能

    Institute of Scientific and Technical Information of China (English)

    周磊; 王立; 俞豪杰; 高敬民; 丁文兵; 高浩其

    2013-01-01

    A new ferrocene modified graphene oxide nano-material (GO-EDA-Fc) was synthesized via a new synthesis route.The GO-EDA-Fc was characterized by Fourier transform infrared spectra,and its morphology was observed under scanning electron microscopy.The graphene oxide was covalently decorated by ferrocene.The catalytic performance of GO-EDA-Fc in the thermal decomposition of ammonium perchlorate(AP) was investigated by thermogravimetric analysis (TGA).The results showed that GO-EDA-Fc exhibited high catalytic activity.When 4wt% of GO-EDA-Fc was added,the peak temperature of the high-temperature decomposition peak of AP had a decrease of 60℃ and the peak of the low-temperature decomposition was shifted to lower as well.The more GO-EDA-Fc was added,the better catalytic performance would be achieved.Notably,the ferrocene functionalized graphenc oxide had shown a synergistic catalytic effect.The mechanism of promote action was also investigated.%本文通过一种新的合成路线合成了二茂铁功能化的氧化石墨烯(GO-EDA-Fc).利用傅里叶变换红外光谱和扫描电子显微镜对其结构和形貌进行了表征.通过热重分析(TGA)研究了其对高氯酸铵(AP)热分解的催化性能,结果表明,氧化石墨烯和二茂铁表现出很好的协同催化效果,对AP热分解具有高的催化活性.催化效果随着GO-EDA-Fc加入量的增加而增强,当加入4wt%的GO-EDA-Fc时,AP的高温分解峰的峰值温度下降了60℃,低温分解峰的峰值也有降低.文中还对催化机制进行了研究.

  20. 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

  1. Hydrogen production from catalytic decomposition of methane; Produccion de hidrogeno a partir de la descomposicion termica catalitica del biogas de digestion anaerobia

    Energy Technology Data Exchange (ETDEWEB)

    Belsue Echevarria, M.; Etxebeste Juarez, O.; Perez Gil, S.

    2002-07-01

    The need of substitution of part of the energy obtained from fossil fuels instead of energy from renewable sources, together with the minimal emissions of CO{sub ''} and CO that are expected with these technologies, make renewable sources a very attractive predecessor for the production of hydrogen. In this situation, a usable source for hydrogen production is the biogas achieved by means of technologies like the anaerobic digestion of different kinds of biomass (MSW, sewage sludge, stc.). In this article we suggest the Thermal Catalytic Decomposition of the methane contained in this biogas, after separation of pollutants like CO{sub ''}, H{sub 2}S. steam. This technology will give hydrogen, usable in fuel cells, and nanoestructured carbon as products. (Author) 7 refs.

  2. Catalytic Decomposition of CFC-12 over Heteropolyacids%杂多酸催化分解氟里昂-12

    Institute of Scientific and Technical Information of China (English)

    马臻; 华伟明; 唐颐; 高滋

    2000-01-01

    @@ Chlorine atoms from chlorofluorocarbons (CFCs) deplete stratospheric ozone and CFCs are green-house gases too. Owing to these environmental problems, many kinds of CFCs have been banned since the Montreal Protocol and two kinds of cleaning techniques have been developed. One is the synthesis of CFCs alternatives[1,2] and the other is the decomposition of banned CFCs in existing equipments[3,4].

  3. Surface characterization studies on the interaction of V2O5-WO3/TiO2 catalyst for low temperature SCR of NO with NH3

    Science.gov (United States)

    Zhang, Shule; Zhong, Qin

    2015-01-01

    This study aimed at elucidating the surface characterization of V2O5-WO3/TiO2 catalyst to investigate the interaction of V, W and Ti species for the improvement of the catalytic activity in the SCR reaction at low-temperature. Analysis by XRD, UV-vis, PL spectra and DFT theoretical calculations, XPS, EPR and in situ DRIFT showed that WO3 could interact with TiO2 to improve the electrons transfer, and the WO3 hybridization with V2O5 could also improve the reducibility and formation of reduced V2O5 species for the V2O5-WO3/TiO2 catalyst. These aspects resulted in the NO oxidation and NO3 - decomposition that were responsible for the high catalytic activity of V2O5-WO3/TiO2 catalyst.

  4. Theoretical kinetic study of the low temperature oxidation of ethanol

    CERN Document Server

    Fournet, René; Bounaceur, Roda; Molière, Michel

    2009-01-01

    In order to improve the understanding of the low temperature combustion of ethanol, high-level ab initio calculations were performed for elementary reactions involving hydroxyethylperoxy radicals. These radicals come from the addition of hydroxethyl radicals (?CH3CHOH and ?CH2CH2OH) on oxygen molecule. Unimolecular reactions involving hydroxyethylperoxy radicals and their radical products were studied at the CBS-QB3 level of theory. The results allowed to highlight the principal ways of decomposition of these radicals. Calculations of potential energy surfaces showed that the principal channels lead to the formation of HO2 radicals which can be considered, at low temperature, as slightly reactive. However, in the case of CH3CH(OOH)O? radicals, a route of decomposition yields H atom and formic peracid, which is a branching agent that can strongly enhance the reactivity of ethanol in low temperature oxidation. In addition to these analyses, high-pressure limit rate constants were derived in the temperature rang...

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

    Energy Technology Data Exchange (ETDEWEB)

    Sung, K. W.; Na, J. W.; Cho, Y. H.; Kim, K. R

    1999-01-01

    In an experiment on TiO{sub 2} photo-catalysis of five nitrogen-containing organic compounds, the changes of pH and total carbon contents were measured, and the dependence of their photo-catalytic characteristic upon their chemical structures were investigated. -- calculation of the effect of ionic carbon species in an aqueous solution on thermodynamic equilibrium, pH and conductivity showed a small quantity of organics could lead conductivity increase and pH reduction. -- Based on the results of photo-catalytic experiment of ethylamine, phenylhydrazine, pyridine, urea or EDTA, irradiated for 180 minutes after adsorption onto titanium dioxide for 60 minutes, relationship between nitrogen atomic charge and the first-order rate constant was as the following: R (1st - order rate constant) = {delta} ({epsilon} - a ){sup 1/3} + b where, {epsilon} : atomic charge of nitrogen in a molecular, {delta}, a and b : corrective coefficients.

  6. Effect of surface structure on the catalytic behavior of Ni:Cu/Al and Ni:Cu:K/Al catalysts for methane decomposition

    Institute of Scientific and Technical Information of China (English)

    S.Tajammul Hussain; Sheraz Gul; Muhammed Mazhar; Dalaver H.Anjum; Faical Larachi

    2008-01-01

    Methane decomposition using nickel, copper, and aluminum (Ni:Cu/Al) and nickel, copper, potassium, and alu-minum (Ni:Cu:K/Al) modified nano catalysts has been investigated for carbon fibers, hydrogen and hydrocarbon production. X-ray photoelectron spectroscopy (XPS), static secondary ion mass spectrometry (SSIMS), thermal gravimetric analysis (TGA),Fourier transform infrared (FT-IR), secondary electron microscopy/X-ray energy dispersive (SEM-EDX), and temperature pro-grammed desorption (TPD) were used to depict the chemistry of the catalytic results. These techniques revealed the changes in surface morphology and structure of Ni, Cu, Al, and K, and formation of bimetallic and trimetallic surface cationic sites with sifferent cationic species, which resulted in the production of graphitic form of pure carbon on Ni:Cu/Al catalyst. The addition of K has a marked effect on the product selectivity and reactivity of the catalyst system. K addition restricts the formation of carbon on the surface and increases the production of hydrogen and C2, C3 hydrocarbons during the catalytic reaction whereas no hydrocarbons are produced on the sample without K. This study completely maps the modified surface structure and its re-lationship with the catalytic behavior of both systems. The process provides a flexible route for the production of carbon fibers and hydrogen on Ni:Cu/Al catalyst and hydrogen along with hydrocarbons on Ni:Cu:K/Al catalyst. The produced carbon fibers are imaged using a transmission electron microscope (TEM) for diameter size and wall structure determination. Hydrogen produced is COx free, which can be used directly in the fuel cell system. The effect of the addition of Cu and its transformation and interaction with Ni and K is responsible for the production of CO/CO2 free hydrogen, thus producing an environmental friendly clean energy.

  7. 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...

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

    Institute of Scientific and Technical Information of China (English)

    Wang Minwei; Li Fengyi

    2004-01-01

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

  9. Combined effects Na and SO{sub 2} in flue gas on Mn-Ce/TiO{sub 2} catalyst for low temperature selective catalytic reduction of NO by NH{sub 3} simulated by Na{sub 2}SO{sub 4} doping

    Energy Technology Data Exchange (ETDEWEB)

    Zhou, Aiyi [Department of Environmental Science and Engineering, Nanjing Normal University, Nanjing 210023 (China); Jiangsu Provincial Key Laboratory of Materials Cycling and Pollution Control, Nanjing 210023 (China); Yu, Danqing [School of Chemical Engineering and Technology, Wuhan University of Science and Technology, Wuhan 430081 (China); Yang, Liu [Department of Environmental Science and Engineering, Nanjing Normal University, Nanjing 210023 (China); Jiangsu Provincial Key Laboratory of Materials Cycling and Pollution Control, Nanjing 210023 (China); Sheng, Zhongyi, E-mail: 09377@njnu.edu.cn [Department of Environmental Science and Engineering, Nanjing Normal University, Nanjing 210023 (China); Jiangsu Provincial Key Laboratory of Materials Cycling and Pollution Control, Nanjing 210023 (China)

    2016-08-15

    Highlights: • Sodium sulfate (Na{sub 2}SO{sub 4}) was deposited on Mn-Ce/TiO{sub 2} catalyst to simulate the co-existing of sodium and SO{sub 2} in the flue gas. • Na{sub 2}SO{sub 4} had strong and fluctuant influence on Mn-Ce/TiO{sub 2} catalyst’s performance in SCR of NOx with NH{sub 3}, due to the combined effect of the deactivation of sodium salts and the enhanced performance of ceria with surface sulfation. • The changes of the surface chemical species and acid sites on the Na{sub 2}SO{sub 4} deposited catalysts could be considered as the main reasons for the fluctuation changes with the catalytic activity. - Abstract: A series of Mn-Ce/TiO{sub 2} catalysts were synthesized through an impregnation method and used for low temperature selective catalytic reduction (SCR) of NOx with ammonia (NH{sub 3}). Na{sub 2}SO{sub 4} was added into the catalyst to simulate the combined effects of alkali metal and SO{sub 2} in the flue gas. Experimental results showed that Na{sub 2}SO{sub 4} had strong and fluctuant influence on the activity of Mn-Ce/TiO{sub 2}, because the effect of Na{sub 2}SO{sub 4} included pore occlusion and sulfation effect simultaneously. When Na{sub 2}SO{sub 4} loading content increased from 0 to 1 wt.%, the SCR activities of Na{sub 2}SO{sub 4}-doped catalysts decreased greatly. With further increasing amount of Na{sub 2}SO{sub 4}, however, the catalytic activity increased gradually. XRD results showed that Na{sub 2}SO{sub 4} doping could induce the crystallization of MnOx phases, which were also confirmed by TEM and SEM results. BET results showed that the surface areas decreased and a new bimodal mesoporous structure formed gradually with the increasing amount of Na{sub 2}SO{sub 4}. XPS results indicated that part of Ce{sup 4+} and Mn{sup 3+} were transferred to Ce{sup 3+} and Mn{sup 4+} due to the sulfation after Na{sub 2}SO{sub 4} deposition on the surface of the catalysts. When the doped amounts of Na{sub 2}SO{sub 4} increased, NH{sub 3

  10. Catalytic decomposition of ammonia in fuel gas produced in pilot-scale pressurized fluidized-bed gasifier

    Energy Technology Data Exchange (ETDEWEB)

    Mojtahedi, W.; Ylitalo, M.; Maunula, T.; Abbasian, J. [Enviropower Inc., Tampere (Finland)

    1995-12-01

    Integrated Gasification Combined Cycle (IGCC) process, incorporating pressurized gasification of solid fuels (coal, peat, biomass) and hot gas cleanup, is being developed worldwide to generate power with high efficiency and in an environmentally acceptable manner. The gasifier product gas contains, among others, ammonia and to a lesser extent hydrogen cyanide (HCN) which are converted to oxides of nitrogen (NO{sub x}) when the gas is combusted in the gas turbine. Several nickel-based catalysts were developed and evaluated for decomposition of ammonia present in the gasifier product gas, at Enviropower`s 15 MW{sub th} pilot plant in coal- and biomass-gasification tests. Up to 75% of ammonia in the product gas was decomposed at 800-900{degree}C temperature range and 12-22 bar pressure. 11 refs., 12 figs., 4 tabs.

  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. 钛基柱撑黏土负载锰铈催化剂低温选择性催化还原脱除NOx研究%Study on Ti-Pillared Interlayered Clays Supported MnOx-CeO2 Catalysts for Selective Catalytic Reduction of NO by NH3 at Low Temperature

    Institute of Scientific and Technical Information of China (English)

    沈伯雄; 马宏卿; 杨晓燕

    2011-01-01

    为探究钛基柱撑黏土(titania pillared interlayeredclays,Ti-PILC)催化剂低温选择性催化还原NO。的活性,实验通过浸渍法制各了MnOx.CeO2/Ti-PILCs,并测试其低温下脱硝活性,同时将TiOSO4、TiCl4钛源制备的催化剂对比。并运用X射线衍射、透射电镜、N2吸附脱附、氨程序升温脱附等技术对2种催化剂进行表征分析,实验发现以TiOSO4为钛源比以TiCl4为钛源制备的MnO2-CeO2/Ti-PILC具有更好的脱硝活性。以TiOSO4为钛源制备的MnOx-CeO2Ti-PILC在nTi/mclay=15mmol/g时活性最高,在200℃时,其NO脱除效率高达95%以上。%In order to study the selective catalytic reduction (SCR) activity of NOx of the titania pillared interlayered clays (Ti-PILC) related catalysts, MnOx-CeO2 were introduced to Ti-pillared interlayered clays with different titania precursors including TiOSO4 and TiCl4 by impregnating method. MnOx-CeO2/ Ti-PILCs were studied as catalysts of selective catalytic reduction of NO with NH3 at low temperature. The obtained catalysts were characterized by X-ray diffraction (XRD), transmission electron microscope (TEM), N2 adsorption-desorption and NH3-temperature programmed desorption measurements. The results showed that MnOx- CeOJTi-PILC prepared with TiOSO4 showed better de-NOx activity than that with TiCI4. The de-NO efficiency of MnOx-CeO2/Ti-PILC prepared with the precursor TiOSO4 is higher than 95% at 200℃, and the best nTi/melay was 15 mmol/g.

  13. NO Removal by Low-temperature Selective Catalytic Reduction on Mn-Ce/Ti-Zr-OPILC Catalyst%Mn-Ce/Ti-Zr-柱撑膨润土催化剂低温选择性催化还原法脱硝

    Institute of Scientific and Technical Information of China (English)

    沈伯雄; 吴姁徐; 马宏卿; 邢玉姗; 张馨予

    2012-01-01

    Using the modified organic clay as raw matieral, Ti-Zr co-pillared organic clay(Ti-Zr-OPILC) was prepared, and then loaded with Mn and Ce by impregnation method to prepare the catalyst of Mn-Ce/ Ti-Zr-OPILC. The catalyst was characterized by XRD and BET, Its catalytic activity for NO selective catalytic reduction at low temperature was studied. The experimental results show that: The specific surface area of the catalyst is greatly increased and the dispersion of Mn and Ce on the carrier is good; When the reaction temperature is 220℃, the volume space velocity is 40 000 h-1, n(NH3) :n(NO)=1, the initial volume fractions of NO and O2 are 0.06% and 3.6% respectively, the removal rate of NO can reach over 95%.%以改性的有机膨润土为原料,制备Ti、Zr共柱撑有机膨润土(Ti-Zr-OPILC),并通过浸渍法负载Mn、Ce,制备得催化剂Mn-Ce/Ti-Zr-OPILC,运用XRD、BET分析了催化剂的物理化学特性,并考察了催化剂对NO低温选择性催化还原反应的催化活性.实验结果表明:催化剂的比表面积得到很大提高,Mn和Ce在载体上分散性较好;在反应温度为220℃、体积空速为40 000 h-1、n(NH3)∶n(NO)为1、初始NO体积分数为0.06%、O2体积分数为3.6%时,对NO去除率高达95%以上.

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

    Institute of Scientific and Technical Information of China (English)

    M.H.Khedr

    2006-01-01

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

  15. Catalytic Decomposition of Nitric Oxide over Nano-sized PbTiO3 Supported Cupric Oxide%纳米晶PbTiO3负载CuO催化NO分解

    Institute of Scientific and Technical Information of China (English)

    邢丽; 薛念华; 陈向科; 郭学锋; 丁维平; 陈懿

    2005-01-01

    A large specific surface area perovskite-type mixed oxide PbTiO3 supported cupric oxide was synthesized as a catalyst for NO decomposition and characterized by techniques such as XPS, XRD,H2-TPR before and after NO deconlposition reactions. The catalytic properties were tested with a fix-bed micro-reactor. The results showed that the PbTiO3 was inactive for the reactions, but 1wt % Cu/PbTiO3 catalyst gave fairly good activities for NO decomposition at temperature as low as 473K. Copper species were found well-dispersed but weakly interacted with the support before NO decomposition, and the NO decomposition caused significant change in the environment of the copper species, which became Cu(Ⅰ) and most probably incorporated into surface crystal lattice of the nano-sized PbTiO3. In NO reaction, a large amount of oxygen atoms from the decomposition of NO penetrated into the nano-sized PbTiO3 support and caused small expansion of crystal lattice. The transport of oxygen between the copper species and the catalyst support may be helpful to speed up the kinetic regeneration of active metal sites from oxygen occupancy and resulted in good catalytic performance.

  16. Structure–acidity correlation of supported tungsten(VI)-oxo-species: FT-IR and TPD studies of adsorbed pyridine and catalytic decomposition of 2-propanol

    Energy Technology Data Exchange (ETDEWEB)

    Zaki, M.I., E-mail: mizaki@mu.edu.eg; Mekhemer, G.A.H.; Fouad, N.E.; Rabee, A.I.M.

    2014-07-01

    The amount of 10 wt%-WO{sub 3} was supported on alumina, titania or silica by impregnation with aqueous solution of ammonium paratungstate and subsequent calcination at 500 °C for 10 h. Tungstate-related chemical and physical changes in the calcination products were resolved by ex-situ infrared (IR) spectroscopy. Nature of exposed surface acid sites were probed by in-situ IR spectroscopy of adsorbed pyridine (Py) molecules at room temperature (RT). The relative strength of the acid sites thus probed was gauged by combining results of temperature-programmed desorption (TPD) measurements of the RT-adsorbed Py with those communicated by in-situ IR spectra of residual Py on the surface after a brief thermoevacuation at high temperatures (100–300 °C). Reactivity of the surface acid sites was tested toward 2-propanal catalytic decomposition, and observed by in-situ IR gas phase spectra. Results obtained were correlated with predominant structures assumed by the supported tungstate species. Accordingly, polymerization of the supported tungstate into 2-/3-dimensional structures, was found to be relatively most advanced on favorable locations of titania surfaces as compared to the case on alumina or silica surfaces. Consequently, the Lewis acidity was strengthened, and strong Bronsted acidity was evolved, leading to a 2-propanol dehydration catalyst (tungstate/titania) of optimal activity and selectivity. Strong tungstate/support interfacial interactions were found to hamper the formation of the strongly acidic and catalytically active polymeric structures of the supported tungstate (i.e., the case on alumina or silica).

  17. Low temperature conversion of plastic waste into light hydrocarbons

    Energy Technology Data Exchange (ETDEWEB)

    Shah, Sajid Hussain; Khan, Zahid Mahmood; Raja, Iftikhar Ahmad; Mahmood, Qaisar; Bhatti, Zulfiqar Ahmad; Khan, Jamil; Farooq, Ather; Rashid, Naim [Department of Environmental Sciences, COMSATS Institute of Information Technology, Abbottabad 22060 (Pakistan); Wu, Donglei, E-mail: wudl@zju.edu.cn [Department of Environmental Engineering, Zhejiang University, Hangzhou 310029 (China)

    2010-07-15

    Advance recycling through pyrolytic technology has the potential of being applied to the management of plastic waste (PW). For this purpose 1 l volume, energy efficient batch reactor was manufactured locally and tested for pyrolysis of waste plastic. The feedstock for reactor was 50 g waste polyethylene. The average yield of the pyrolytic oil, wax, pyrogas and char from pyrolysis of PW were 48.6, 40.7, 10.1 and 0.6%, respectively, at 275 deg. C with non-catalytic process. Using catalyst the average yields of pyrolytic oil, pyrogas, wax and residue (char) of 50 g of PW was 47.98, 35.43, 16.09 and 0.50%, respectively, at operating temperature of 250 deg. C. The designed reactor could work at low temperature in the absence of a catalyst to obtain similar products as for a catalytic process.

  18. 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.

  19. Decomposition of Methanol over Pd/Ce/γ-Al2O3 and Pd/Ce-La/γ-Al2O3 Catalysts%Pd/Ce/γ-Al2O3和Pd/Ce-La/γ-Al2O3甲醇低温裂解催化剂

    Institute of Scientific and Technical Information of China (English)

    杨成; 陈小平; 王秀芝; 任杰; 孙予罕

    2000-01-01

    @@ Methanol is an alternative fuel for automobiles in the future. Decomposition of methanol by on-board reforming into H2 and CO as the feed for the engine has received increasing attention owing to energy saving and environmentally benign aim[1,2]. To meet the requirements of the process, new catalysts with high activity at low temperatures are indispensable. Several catalytic systems have been evaluated for methanol decomposition, but high reaction temperature and side reactions were always problems[3].

  20. Metathesis in the generation of low-temperature gas in marine shales

    OpenAIRE

    Jarvie Daniel M; Mango Frank D

    2010-01-01

    Abstract The recent report of low-temperature catalytic gas from marine shales took on additional significance with the subsequent disclosure of natural gas and low-temperature gas at or near thermodynamic equilibrium in methane, ethane, and propane. It is important because thermal cracking, the presumed source of natural gas, cannot generate these hydrocarbons at equilibrium nor can it bring them to equilibrium over geologic time. The source of equilibrium and the source of natural gas are e...

  1. [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.

  2. [Study on mechanism of ceramic honeycomb-catalytic ozonation for the decomposition of trace nitrobenzene in aqueous solution].

    Science.gov (United States)

    Zhao, Lei; Ma, Jun; Sun, Zhi-Zhong; Liu, Zheng-Qian; Yang, Yi-Xin; Lu, Wei

    2007-02-01

    The experiment investigated effects of the presence of hydroxyl radical inhibitor on degradation efficiency of trace nitrobenzene in aqueous solution in the processes of ozonation alone and ceramic honeycomb-catalyzed ozonation, including HCO3-, CO3(2-), HPO4(2-), H2PO4- and tert-butanol, and studied preliminarily on their mechanism. The results indicated that degradation rate of the two processes both increased firstly and decreased subsequently with the increase of the concentration of HCO3- (0 - 200 mg x L(-1)), and reached the climax at the concentration of bicarbonate ion 50 mg x L(-1) under the same experimental condition. The degradation rates of ozonation alone and ozonation/ ceramic honeycomb both declined by 16.57% and 27.52% with the increase of the concentration of CO3(2-) (0 - 20 mg x L(-1)), respectively, and decreased by 13.61% and 17.52% with the addition of the concentration of HPO4(2-) (0 - 12 mg x L(-1)), and reduced by 6.61% and 12.52% with the enhancement of the concentration of H2PO4- (0 - 120 mg x L(-1)), and dropped by 30.06% and 46.09% with the increasing of the concentration of tert-butanol (0 - 10 mg x L(-1)). The experimental results indicated that decomposition of nitrobenzene in both processes all followed the mechanism of oxidization by OH free radical, and tert-butanol is a more suitable indicator for the radical type reaction. The removal rate of ozonation alone rose with the increase of the concentration of pH (3.02 - 10.96), but that of ozonation/ceramic honeycomb process reached the maximum at pH = 9.23.

  3. 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.

  4. Optimization to Low Temperature Activity in Psychrophilic Enzymes

    Directory of Open Access Journals (Sweden)

    Caroline Struvay

    2012-09-01

    Full Text Available Psychrophiles, i.e., organisms thriving permanently at near-zero temperatures, synthesize cold-active enzymes to sustain their cell cycle. These enzymes are already used in many biotechnological applications requiring high activity at mild temperatures or fast heat-inactivation rate. Most psychrophilic enzymes optimize a high activity at low temperature at the expense of substrate affinity, therefore reducing the free energy barrier of the transition state. Furthermore, a weak temperature dependence of activity ensures moderate reduction of the catalytic activity in the cold. In these naturally evolved enzymes, the optimization to low temperature activity is reached via destabilization of the structures bearing the active site or by destabilization of the whole molecule. This involves a reduction in the number and strength of all types of weak interactions or the disappearance of stability factors, resulting in improved dynamics of active site residues in the cold. Considering the subtle structural adjustments required for low temperature activity, directed evolution appears to be the most suitable methodology to engineer cold activity in biological catalysts.

  5. 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.

  6. 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.

  7. 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.

  8. 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

  9. 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.

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

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

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

  11. Effects of alkali metals on catalyst of MnOx-CeO2/ZrO2-PILC in the low-temperature selective catalytic reduction%碱土金属对MnOx-CeO2/ZrO2-PILC催化剂SCR活性影响研究

    Institute of Scientific and Technical Information of China (English)

    沈伯雄; 陈建宏; 姚燕; 胡国丽

    2012-01-01

    The poisoning effects of alkali metals on low-temperature selective catalytic reduction (SCR) catalyst MnOx-CeO2/ZrO2-PILC were invested by the method of impregnation in the laboratory. It was indicated that the addition of Ca/Mg would decrease the activities of the catalyst, and the poisoning effects were contacted with the amount and acidity of the doped-alkali metal. X-ray diffraction (XRD) , H2-temperature programmed reduction (H2-TPR) , N2 adsorption-desorption and temperature-programmed desorption of NH3(NH3-TPD) were used to characterize the properties of the fresh and alkali earth doped catalysts. According to the results, the doped-alkali metals would inhibit the reduction properties, induce the loss in surface area and surface acidity.%采用浸渍法模拟低温选择性催化还原(SCR)催化剂MnOx-CeO2/ZrO2-PILC的碱土金属中毒特性,研究了碱土金属及其负载量对中毒程度的影响.实验表明,钙/镁的添加会引起催化剂中毒,催化剂中毒失活程度与碱土金属的负载量有关.运用X射线衍射(XRD)、H2程序升温还原(H2-TPR)、氮气吸脱附及NH3程序升温脱附(NH3-TPD)对新鲜催化剂以及碱土金属中毒后的催化剂进行了表征.结果表明,钙/镁中毒后催化剂的比表面积降低、催化剂氧化还原性和表面酸性减少,进而造成催化剂失活.

  12. 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.

  13. 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...

  14. 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.

  15. Activity and antitoxic properties of Cr--MnOx/TiO2--ZrO2 for low-temperature selective catalytic reduction of NO%Cr--MnOx/TiO2--ZrO2低温选择催化还原NO的活性及抗毒性能

    Institute of Scientific and Technical Information of China (English)

    李哲; 汪莉; 贠丽; 王振南; 李梦霞; 李鑫

    2015-01-01

    采用溶胶凝胶法制备TiO2-ZrO2载体,然后采用柠檬酸溶液浸渍法制备Cr-MnOx/TiO2-ZrO2复合催化剂.通过X射线衍射、比表面积测试( BET)、扫描电镜、X射线光电子能谱等测试方法对催化剂的物化性能进行表征分析,并进行NH3选择性催化还原NO实验,考察催化剂在低温下的活性及抗硫抗水性能. Cr元素介入到MnOx 中,形成了新型的CrMn1.5 O4活性物相,其中的Mn元素多以Mn3+和Mn4+存在.高价态的Cr5+使Mn元素由Mn3+向高氧化态的Mn4+转化,有利于低温选择性催化还原反应的进行.鉴于Cr元素第一电离能和电负性均低于Mn元素,能优先于Mn与SO2-4和SO2-3结合,保护MnOx 不被硫酸化,从而提高Cr-MnOx/TiO2-ZrO2催化剂的抗毒性能.制备的五种不同Cr/(Cr+Mn)摩尔比的催化剂中,Cr(0.4)-MnOx/TiO2-ZrO2的性能最优,其颗粒分散均匀,具有较大比表面积,在180℃时脱硝效率能够达到95.8%,同时通入5% H2 O和10-4 SO2,脱硝效率缓慢下降,反应8 h后,下降到73%,并保持稳定.%Using a sol-gel prepared TiO2- ZrO2 carrier, Cr- MnOx/TiO2- ZrO2 composite catalysts were synthesized by a critic acid solution impregnation method. The physical and chemical properties of the catalysts were characterized by X-ray diffraction, specific surface area determination ( BET) , scanning electron microscopy and X-ray photoelectron spectroscopy. Meanwhile, the low-temperature catalytic activity and the sulfur and water resistance were evaluated with selective catalytic reduction ( SCR) of NO by NH3. The introduction of Cr element to MnOx yields a new CrMn1.5O4 active phase, in which Mn primarily exists as Mn3+ and Mn4+. The Cr5+ valence state facilitates the transformation of Mn3+ to high oxidation state Mn4+, which is beneficial to the low temperature SCR reaction. Because of lower first ionization energy and electronegativity, Cr preferentially reacts with SO2-4 and SO2-3 than Mn, thus protecting MnOx not to be sulphatized and

  16. 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.

  17. 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

  18. Influence of preparation on the catalytic performances of zirconia based catalysts for high temperature N{sub 2}O decomposition; Influence des conditions de preparation sur les performances de catalyseurs a base de zircone pour la decomposition du N{sub 2}O a tres haute temperature

    Energy Technology Data Exchange (ETDEWEB)

    Esteves, Ph.; Granger, P.; Leclercq, L.; Leclercq, G.; Payen, E. [Universite des Sciences et technologies de Lille, 59 - Villeneuve d' Ascq (France); Kieger, St. [Grande Paroisse S.A., Usine de Rouen, 76 - Grand Quevilly (France); Navascues, L. [Grande Paroisse S.A., 92 - Paris la Defense (France)

    2001-07-01

    Various preparation procedures of zirconia based catalysts modified by additives and their catalytic properties in the decomposition of N{sub 2}O at high temperature have been investigated. The most relevant observation was for ZrO{sub 2} containing 1% of additive with a synergy effect in comparison with a reference ZrO{sub 2} catalyst. For higher additive contents such a synergy effect disappears. (authors)

  19. 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...

  20. 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.

  1. 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

  2. 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.

  3. 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.

  4. 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.

  5. 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

  6. Low temperature spark plasma sintering of TC4/HA composites

    Institute of Scientific and Technical Information of China (English)

    Huiliang Shao; Lei Cao; Daqian Sun; Zhankui Zhao

    2016-01-01

    Ti6Al4V/hydroxyapatite composites (TC4/HA) have been prepared by high energy ball milling and low temperature spark plasma sintering at 600 °C, 550 °C, 500 °C and 450 °C, respectively. The sintering temperature of the composites was sharply decreased as the result of the activation and surficial modification effects induced from high energy ball milling. The decomposition and reaction of hydro-xyapatite was successfully avoided, which offers the composites superior biocompatibility. The hydro-xyapatite in the composites was distributed in gap uniformly, and formed an ideal network structure. The lowest hardness, compressive strength and Young's modulus of the composites satisfy the requirements of human bone.

  7. Low-temperature SCR activity and SO2 deactivation mechanism of Ce-modified V2O5–WO3/TiO2 catalyst

    Directory of Open Access Journals (Sweden)

    Ziran Ma

    2015-08-01

    Full Text Available The promotion effect of ceria modification on the low-temperature activity of V2O5-WO3/TiO2 catalyst was evaluated for the selective catalytic reduction of NO with NH3 (NH3-SCR. The catalytic activity of 1 wt% V2O5-WO3/TiO2 was significantly enhanced by the addition of 8 wt% ceria, which exhibited a NOx conversion above 80% in a broad temperature range 190–450 °C. This performance was comparable with 3 wt%V2O5-WO3/TiO2, indicating that the addition of ceria contributed to reducing the usage of toxic vanadia in developing low-temperature SCR catalysts. Moreover, V1CeWTi exhibited approximately 10% decrease in NOx conversion in the presence of 60 ppm SO2. The characterization results indicated that active components of V, W and Ce were well dispersed on TiO2 support. The synergetic interaction between Ce and V species by forming V–O–Ce bridges enhanced the reducibility of VCeWTi catalyst and thus improved the low-temperature activity. The sulfur poisoning mechanism was also presented on a basis of the designed TPDC (temperature-programmed decomposition and TPSR (temperature-programmed surface reaction experiments. The deposition of (NH42SO4 on V1CeWTi catalyst was much smaller compared with that on V1Ti. On the other hand, the oxidation of SO2 to SO3 was significantly promoted on the CeO2-modified catalyst, accompanied by the formation of cerium sulfates. Therefore, the deactivation of this catalyst was mainly attributed to the vanishing of the V–Ce interaction and the sulfation of active ceria.

  8. Low-Temperature CO oxidation on multicomponent gold based catalysts

    Directory of Open Access Journals (Sweden)

    Tomas eRamirez Reina

    2013-09-01

    Full Text Available In this work the development of gold catalysts, essentially based on γ-alumina with small superficial fraction of Ce-Fe mixed oxides as support for the low temperature CO oxidation is proposed. Characterization results obtained by means of XPS, UV-Vis spectroscopy and H2-TPR are employed to correlate the activity data with the catalysts composition. The bare γ-alumina supported gold catalyst demonstrates the poorest activity within the series. The addition of CeO2 or FeOX improves the catalytic performance, especially observed for the CeO2-FeOx mixed oxide doped samples. This enhanced CO oxidation activity was related to the Ce-Fe interaction producing materials with promoted redox properties and therefore oxidation activity

  9. 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...

  10. Low-temperature CO oxidation on multicomponent gold based catalysts

    Science.gov (United States)

    Ramírez Reina, Tomás; Ivanova, Svetlana; Centeno, Miguel A.; Odriozola, José A.

    2013-01-01

    In this work the development of gold catalysts, essentially based on γ-alumina with small superficial fraction of Ce-Fe mixed oxides as support for the low temperature CO oxidation is proposed. Characterization results obtained by means of TEM, OSC, XPS, UV-Vis spectroscopy and H2-TPR are employed to correlate the activity data with the catalysts composition. The bare γ-alumina supported gold catalyst demonstrates the poorest activity within the series. The addition of CeO2 or FeOX improves the catalytic performance, especially observed for the CeO2-FeOx mixed oxide doped samples. This enhanced CO oxidation activity was related to the Ce-Fe interaction producing materials with promoted redox properties and therefore oxidation activity. PMID:24790941

  11. Anodes for Solid Oxide Fuel Cells Operating at Low Temperatures

    DEFF Research Database (Denmark)

    Abdul Jabbar, Mohammed Hussain

    An important issue that has limited the potential of Solid Oxide Fuel Cells (SOFCs) for portable applications is its high operating temperatures (800-1000 ºC). Lowering the operating temperature of SOFCs to 400-600 ºC enable a wider material selection, reduced degradation and increased lifetime....... On the other hand, low-temperature operation poses serious challenges to the electrode performance. Effective catalysts, redox stable electrodes with improved microstructures are the prime requisite for the development of efficient SOFC anodes. The performance of Nb-doped SrT iO3 (STN) ceramic anodes...... at 400ºC. The potential of using WO3 ceramic as an alternative anode materials has been explored. The relatively high electrode polarization resistance obtained, 11 Ohm cm2 at 600 ºC, proved the inadequate catalytic activity of this system for hydrogen oxidation. At the end of this thesis...

  12. 新型铬钴复合氧化物中低温选择性催化NOx还原及原位机理研究%A novel Cr-Co mixed-oxide catalyst for selective catalytic reduction of NOx with NH3 at medium-low temperature and in situ DRlFTS research on its reaction mechanism

    Institute of Scientific and Technical Information of China (English)

    薛隆毅; 邓志毅; 陈定盛; 唐志雄; 陈雄波; 方平; 岑超平; 陈志航

    2015-01-01

    采用固相法合成系列铬钴复合氧化物催化剂,该催化体系在中低温[( 180~300 )℃]下具有优异的氨选择性催化氮氧化物还原活性,其中,Cr(0. 5)-CrOx 催化剂在空速50 000 h-1、反应温度200 ℃和220 ℃条件下,NOx转化率达100%.采用原位DRIFIS研究催化剂表面吸附物种以及催化机理,在反应温度220 ℃考察 Cr(0. 5)-CoOx 催化剂表面 NH3 与 NO 的吸附态形式和NH3 -SCR反应过程中中间态及其反应机理.结果表明,Cr(0. 5)-CrOx 催化剂上NH3 吸附在L酸位,也能吸附在B酸位,但只与气态的NOx反应,生成中间体NH2 NO,再进一步反应,最终生成N2 与H2 O.吸附态的NOx不参与SCR反应,反应遵循Eley-Rideal机理.%A series of Cr-Co mixed oxide catalysts was prepared by solid states reaction method,which were used for selective catalytic reduction( SCR)of NOx with NH3 in the presence of excess oxygen at medium-low temperature[(180~300)℃]. The experimental results showed that under the condition of space velocity 50 000 h-1 and reaction temperature 200℃ and 220℃,NOx conversion reached 100% on Cr(0. 5)-CoOx catalyst. In situ diffuse reflectance infrared transform(DRIFT)spectroscopy was em-ployed for investigating the adsorption species on Cr(0. 5)-CoOx catalyst surface and revealing the reac-tion mechanism under reaction temperature 220 ℃. Based on the in situ DRIFTS results,it was found that NH3 was adsorbed on Lewis and Br?nsted acid sites of Cr(0. 5)-CrOx catalyst,and then decomposed into -NH2 . The gas phase NO could bond with -NH2 and form an intermediate NH2 NO,which could further decompose into N2 and H2 O. The adsorbed NOx didn't participate in the SCR reaction. NH3-SCR reaction on Cr(0. 5)-CoOx catalyst mainly followed the Eley-Rideal mechanism.

  13. Synthesis of a novel Pd/Al2O3 catalyst for Ventilation Air Methane combustion with excellent catalytic activity in low temperatures%煤矿乏风甲烷氧化新型Pd/Al2O3催化剂的合成

    Institute of Scientific and Technical Information of China (English)

    刘文革; 郭德勇; 徐鑫

    2012-01-01

    运用溶胶-凝胶法合成了同时具有介孔和三维交联通透型微米级大孔的Al2O3多孔材料,并以其为载体采用浸渍法制备得到一种新型的Pd/Al2O3整体式催化剂,考察了不同助剂Ce,Zr,La及不同的助剂负载量对甲烷催化燃烧活性的影响.实验结果表明,所合成的新型Pd/Al2O3催化剂具有良好的低温活性,在CH4体积百分数为1%,反应气体空速为6 000 h-1的实验条件下,Pd/Al2O3的起燃温度只有227 ℃,认为这主要是采用的Al2O3载体材料中存在的三维交联通透型微米级大孔骨架可以提供快速的传质通道,在骨架中存在的纳米级介孔能提供较大的表面积和单位容量,从而有利于提高活性组分的分散性及有效利用效率,提高催化剂的活性.助剂Zr的加入能够降低催化剂的起燃温度,而助剂Ce对催化剂活性的影响与其添加量有关.%Bimodal A12O3 porous material with both mesopores and three-dimensional interconnected macropores in micrometer-scale was synthesized via sol-gel method. A kind of novel Pd/Al2O3 monolithic catalysts were prepared by impregnation using the as-synthesized A12O3 porous material as the support. Influence of different additives of Ce,Zr, La and different load amount of the additives on methane combustion activity were investigated. The experimental results show that the new synthesized Pd/Al2O3 catalyst has good low temperature activity. Under the experimental conditions of 1%CH4 with reaction gas space velocity of 6 000 h"1 ,the ignition temperature of Pd/Al2O3 is only 227 t. It is considered that the three-dimensional interconnected macropores of A12O3 support can provide fast mass transfer channel;while the nanoscale mesopores in the skeleton can provide large surface area and unit volume,and thus help to increase the catalytic activity by improving the dispersion of the active component and use efficiency. Additives of Zr can reduce the ignition temperature of the catalyst; the

  14. Template-assisted hydrothermally obtained titania-ceria composites and their application as catalysts in ethyl acetate oxidation and methanol decomposition with a potential for sustainable environment protection

    Science.gov (United States)

    Tsoncheva, Tanya; Mileva, Alexandra; Issa, Gloria; Dimitrov, Momtchil; Kovacheva, Daniela; Henych, Jiří; Scotti, Nicola; Kormunda, Martin; Atanasova, Genoveva; Štengl, Vaclav

    2017-02-01

    High surface area mesoporous ceria-titania binary materials with high Lewis acidity and improved reduction properties were synthesized using template assisted hydrothermal technique. The obtained materials were characterized by low temperature nitrogen physisorption, XRD, SEM, TEM, Raman, UV-vis, XPS, FTIR, FTIR of adsorbed pyridine and thermo-programmed reduction with hydrogen. Their catalytic activity was tested in total oxidation of ethyl acetate and methanol decomposition to CO and hydrogen with a potential application in VOCs elimination and alternative fuels, respectively. The structural changes in the binary materials, which could be tuned by the variation in the Ce/Ti ratio and the temperature of hydrothermal treatment, provoked significant changes in their textural, surface and redox properties, which is in close relation to the catalytic activity and selectivity in various catalytic processes. The intimate contact between the individual oxides results in the formation of different catalytic active sites and their role in the studied catalytic reactions was discussed in details.

  15. 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.

  16. 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.

  17. 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.

  18. 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.

  19. Low temperature destruction of PCDD/Fs over V2O5-CeO2/TiO2 catalyst with ozone.

    Science.gov (United States)

    Yu, Ming-Feng; Lin, Xiao-Qing; Yan, Mi; Li, Xiao-Dong; Chen, Tong; Yan, Jian-Hua

    2016-09-01

    Catalytic destruction of PCDD/Fs (polychlorinated dibenzo-p-dioxins and furans) over V2O5-CeO2/TiO2 catalyst was investigated at a low temperature range of 140-180 °C, in the absence and presence of ozone (200 ppm). Nano-TiO2 support was used to prepare the catalyst by step impregnation method. A stable PCDD/Fs-generating system was established to support the catalytic destruction tests. In the presence of ozone alone, destruction efficiencies of PCDD/Fs are between 32.2 and 43.1 % with temperature increasing from 140 to 180 °C. The activity of V2O5-CeO2/TiO2 catalyst alone on PCDD/Fs destruction is also studied. The increase of temperature from 140 to 180 °C enhances the activity of catalyst with destruction efficiencies increasing from 54.7 to 73.4 %. However, ozone addition greatly enhances the catalytic activity of V2O5-CeO2/TiO2 catalyst on PCDD/Fs decomposition. At 180 °C, the destruction efficiency of PCDD/Fs achieved with V2O5-CeO2/TiO2 catalyst and ozone is above 86.0 %. It indicates that the combined use of ozone and catalyst reduces the reaction temperature of PCDD/Fs oxidation and offers a new method to destroy PCDD/Fs with high destruction efficiency at a low temperature. Furthermore, the destruction efficiencies of 17 toxic PCDD/F congeners, achieved with ozone alone, catalyst alone, and catalyst/ozone are analyzed.

  20. 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...

  1. 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.

  2. Cs(x)H(3.0-x)PW12O40 (X = 2.0-3.0) heteropolyacid nano-catalysts for catalytic decomposition of 2,3-dihydrobenzofuran to aromatics.

    Science.gov (United States)

    Kim, Jeong Kwon; Park, Hai Woong; Hong, Ung Gi; Choi, Jung Ho; Song, In Kyu

    2014-11-01

    Cesium-exchanged Cs(x)H(3.0-x)PW12O40 (X = 2.0, 2.3, 2.5, 2.8, and 3.0) heteropolyacid nanocatalysts were prepared, and they were applied to the catalytic decomposition of lignin model compound to aromatics. Successful formation of cesium-exchanged Cs(x)H(3.0-x)PW12O40 (X = 2.0-3.0) catalysts was confirmed by FT-IR, ICP-AES, and XRD measurements. 2,3-Dihydrobenzofuran was employed as a lignin model compound for representing β-5 bond in lignin. Phenol, ethylbenzene, and 2-ethylphenol were mainly produced by the catalytic decomposition of 2,3-dihydrobenzofuran. Conversion of 2,3-dihydrobenzofuran and total yield for main products (phenol, ethylbenzene, and 2-ethylphenol) were closely related to the surface acidity of Cs(x)H(3.0-x)PW12O40 (X = 2.0-3.0) catalysts. Conversion of 2,3-dihydrobenzofuran and total yield for main products increased with increasing surface acidity of the catalysts. Among the catalysts tested, Cs2.5H0.5PW12O40 with the largest surface acidity showed the highest conversion of 2,3-dihydrobenzofuran and the highest total yield for main products. These results indicate that surface acidity of Cs(x)H(3.0-x)PW12O40 (X = 2.0-3.0) catalysts served as an important factor determining the catalytic performance in the decomposition of 2,3-dihydrobenzofuran to aromatics.

  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. 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.

  7. 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.

  8. 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.

  9. 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.

  10. 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.

  11. 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...

  12. Preparation of highly active manganese oxides supported on functionalized MWNTs for low temperature NOx reduction with NH3

    Science.gov (United States)

    Pourkhalil, Mahnaz; Moghaddam, Abdolsamad Zarringhalam; Rashidi, Alimorad; Towfighi, Jafar; Mortazavi, Yadollah

    2013-08-01

    Manganese oxide catalysts (MnOx) supported on functionalized multi-walled carbon nanotubes (FMWNTs) for low temperature selective catalytic reduction (LTSCR) of nitrogen oxides (NOx) with NH3 in the presence of excess O2 were prepared by the incipient wetness impregnation method. These catalysts were characterized by N2 adsorption, Fourier transform infrared spectroscopy (FTIR), transmission electron microscope (TEM), X-ray diffraction (XRD), thermal gravimetric analysis (TGA) and H2-temperature programmed reduction (H2-TPR) methods. The effects of reaction temperature, MnOx loading, calcination temperature and calcination time were investigated. The presence of surface nitrate species under moderate calcination conditions may play a favorable role in the LTSCR of NOx with NH3. Under the reaction conditions of 200 °C, 1 bar, NO = NH3 = 900 ppm, O2 = 5 vol%, GHSV = 30,000 h-1 and 12 wt% MnOx, NOx conversion and N2 selectivity were 97% and 99.5%, respectively. The SCR activity was reduced in the presence of 100 ppm SO2 and 2.5 vol% H2O from 97% to 92% within 6 h at 200 °C, however such an effect was shown to be reversible by exposing the catalyst to a helium flow for 2 h at 350 °C due to thermal decomposition of ammonium sulphate salts.

  13. 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.

  14. 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.

  15. 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.

  16. 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.

  17. 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.

  18. MnO{sub x}-CeO{sub 2} For The Low-Temperature Oxidation Of Diesel Soot

    Energy Technology Data Exchange (ETDEWEB)

    Tikhomirov, K.; Kroecher, O.; Elsener, M.; Wokaun, A.

    2005-03-01

    MnO{sub x}-CeO{sub 2} was found to be a highly active catalyst for the low-temperature oxidation of Diesel soot. The catalytic activity could be traced to the storage of nitrates on the catalyst surface at low temperatures followed by the release of NO{sub 2} when heated over 280 C. The poor sulphur resistance of the catalyst poses the main problem for its practical application. (author)

  19. Catalytic behaviors of CoB and CoB/SiO2 in thermal decomposition of ammonium perchlorate%CoB和CoB/SiO2对AP热分解的催化活性研究

    Institute of Scientific and Technical Information of China (English)

    李茸; 刘祥萱; 王煊军

    2011-01-01

    Silicon-supported cobalt-boron(CoB/SiO2) and cobalt-boron (CoB) nano-sized catalysts were synthesized via chemical deposition method. Their catalytic behavior in the thermal decomposition of ammonium perchlorate( AP) was briefly studied by thermo-gravimetric and differential thermal analysis (TG-DTA). Results show that both CoB/SiO2 and CoB have catalytic effects on the thermal decomposition of AP. CoB/SiO2 is more effective. The high-temperature thermal decomposition temperature of AP was decreased by 166. 2 ℃ with the addition of 5% CoB/SiO2. This effect is mainly attributed to its higher thermodynamic stability compared with CoB,whch is favorable for catalysis.%采用化学沉积方法,制备了纳米尺度CoB和SiO2·负载的CoB/SiO2催化剂.通过热重-差热分析(TG-DTA)实验,研究了催化剂在AP热分解过程中的催化性能.结果表明,CoB和CoB/SiO2对AP热分解均表现出催化活性,CoB/SiO2的活性更强;质量分数5%的CoB/SiO2,可将AP高温热分解峰的峰温降低166.2℃;CoB/SiO2较好的催化效果,归因于其相对CoB更高的热力学稳定性;负载型催化剂的较高热力学稳定性,更有利于其催化活性的履行.

  20. 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

  1. 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.

  2. Low Temperature Waste Immobilization Testing Vol. I

    Energy Technology Data Exchange (ETDEWEB)

    Russell, Renee L.; Schweiger, Michael J.; Westsik, Joseph H.; Hrma, Pavel R.; Smith, D. E.; Gallegos, Autumn B.; Telander, Monty R.; Pitman, Stan G.

    2006-09-14

    The Pacific Northwest National Laboratory (PNNL) is evaluating low-temperature technologies to immobilize mixed radioactive and hazardous waste. Three waste forms—alkali-aluminosilicate hydroceramic cement, “Ceramicrete” phosphate-bonded ceramic, and “DuraLith” alkali-aluminosilicate geopolymer—were selected through a competitive solicitation for fabrication and characterization of waste-form properties. The three contractors prepared their respective waste forms using simulants of a Hanford secondary waste and Idaho sodium bearing waste provided by PNNL and characterized their waste forms with respect to the Toxicity Characteristic Leaching Procedure (TCLP) and compressive strength. The contractors sent specimens to PNNL, and PNNL then conducted durability (American National Standards Institute/American Nuclear Society [ANSI/ANS] 16.1 Leachability Index [LI] and modified Product Consistency Test [PCT]) and compressive strength testing (both irradiated and as-received samples). This report presents the results of these characterization tests.

  3. Low temperature thermal-energy storage

    Energy Technology Data Exchange (ETDEWEB)

    Segaser, C.S.; Christian, J.E.

    1979-03-01

    This report evaluates currently available techniques and estimated costs of low temperature thermal energy storage (TES) devices applicable to Integrated Community Energy Systems (ICES) installations serving communities ranging in size from approximately 3000 (characterized by an electrical load requirement of 2 MWe) to about 100,000 population (characterized by an electrical load requirement of 100 MWe). Thermal energy in the form of either hotness or coldness can be stored in a variety of media as sensible heat by virtue of a change in temperature of the material, or as latent heat of fusion in which the material changes from the liquid phase to the solid phase at essentially a constant temperature. Both types of material are considered for TES in ICES applications.

  4. Performance of MPPC at low temperature

    Institute of Scientific and Technical Information of China (English)

    AN Zheng-Hua; XUE Zhen; SUN Xi-Lei; L(ü) QI-Wen; ZHANG Ai-Wu; NING Fei-Peng; ZHOU Li; SUN Li-Jun; GE Yong-Shuai; LIU Ying-Biao; WU Chong; L(U) Jun-Guang; SHI Feng; HU Tao; CAI Xiao; YU Bo-Xiang; FANG Jian; XIE Yu-Guang; WANG Zhi-Gang

    2012-01-01

    The performance of a MultiPixel Photon Counter (MPPC) from room to liquid nitrogen temperatures were studied.The gain,the noise rate and bias voltage of the MPPC as a function of temperature were obtained.The experimental results show that the MPPC can work at low temperatures.At nearly liquid nitrogen temperatures,the gain of the MPPC drops obviously to 35% and the bias voltage drops about 9 V compared with that at room temperature.The thermal noise rate from 106 Hz/mm at room temperature drops abruptly to 0 Hz/mm at -100 ℃.The optimized operation point can be acquired by the experiment.

  5. Low temperature properties of erbium in gold

    Energy Technology Data Exchange (ETDEWEB)

    Fleischmann, A.; Schoenefeld, J.; Sollner, J.; Enss, C.; Adams, J.S.; Bandler, S.R.; Kim, Y.H.; Seidel, G.M.

    2000-01-01

    The properties of dilute alloys of Er in Au have been studied, principally below 100 mK, in connection with the use of this system in thermometry and in microcalorimetry for particle detection. Measurements are reported of (1) the magnetization at high temperatures and high field, (2) the magnetization in low fields with temperatures extending down to 0.1 mK, and (3) the heat capacity as a function of temperature and field at low temperatures. These measurements are analyzed to provide information of several properties of the Er{sup 3+} ion in the Au lattice, in particular, the crystal field parameters, the exchange interaction of the 4f electrons with the conduction electrons, and the spin glass freezing temperature.

  6. Low-temperature geothermal resources of Washington

    Energy Technology Data Exchange (ETDEWEB)

    Schuster, J.E. [Washington State Dept. of Natural Resources, Olympia, WA (United States). Div. of Geology and Earth Resources; Bloomquist, R.G. [Washington State Energy Office, Olympia, WA (United States)

    1994-06-01

    This report presents information on the location, physical characteristics, and water chemistry of low-temperature geothermal resources in Washington. The database includes 941 thermal (>20C or 68F) wells, 34 thermal springs, lakes, and fumaroles, and 238 chemical analyses. Most thermal springs occur in the Cascade Range, and many are associated with stratovolcanoes. In contrast, 97 percent of thermal wells are located in the Columbia Basin of southeastern Washington. Some 83.5 percent are located in Adams, Benton, Franklin, Grant, Walla Walla, and Yakima Counties. Yakima County, with 259 thermal wells, has the most. Thermal wells do not seem to owe their origin to local sources of heat, such as cooling magma in the Earth`s upper crust, but to moderate to deep circulation of ground water in extensive aquifers of the Columbia River Basalt Group and interflow sedimentary deposits, under the influence of a moderately elevated (41C/km) average geothermal gradient.

  7. Preparation of silver nanoparticles at low temperature

    Energy Technology Data Exchange (ETDEWEB)

    Mishra, Mini, E-mail: mishramini5@gmail.com [Centre of Environmental Science, Department of Botany, University of Allahabad, Allahabad, U.P. (India); Chauhan, Pratima, E-mail: mangu167@yahoo.co.in [Department of Physics, University of Allahabad, Allahabad U.P. (India)

    2016-04-13

    Silver from ancient time is used as antimicrobial agent in the bulk form but now with the advancement in nanotechnology silver in the form of nanoparticles shown potential effect against microbes which make us easy to fight with many diseases plants and animals. In this work silver nanoparticles were synthesized by chemical routes using sodium borohydride as reducing agent at low temperature. The particles were characterized through UV-Visible spectroscopy as well as X-Ray Diffraction. The UV-visible spectra of silver nanoparticles exhibited absorption at 425 cm; the crystallite size of the particles is between 19nm to 39nm. EDAX graph shows two peaks of silver and oxygen. Water absorbed by silver nanoparticles was removed by the calcinations.

  8. Ultra-low temperature MAS-DNP

    Science.gov (United States)

    Lee, Daniel; Bouleau, Eric; Saint-Bonnet, Pierre; Hediger, Sabine; De Paëpe, Gaël

    2016-03-01

    Since the infancy of NMR spectroscopy, sensitivity and resolution have been the limiting factors of the technique. Regular essential developments on this front have led to the widely applicable, versatile, and powerful spectroscopy that we know today. However, the Holy Grail of ultimate sensitivity and resolution is not yet reached, and technical improvements are still ongoing. Hence, high-field dynamic nuclear polarization (DNP) making use of high-frequency, high-power microwave irradiation of electron spins has become very promising in combination with magic angle sample spinning (MAS) solid-state NMR experiments. This is because it leads to a transfer of the much larger polarization of these electron spins under suitable irradiation to surrounding nuclei, greatly increasing NMR sensitivity. Currently, this boom in MAS-DNP is mainly performed at minimum sample temperatures of about 100 K, using cold nitrogen gas to pneumatically spin and cool the sample. This Perspective deals with the desire to improve further the sensitivity and resolution by providing "ultra"-low temperatures for MAS-DNP, using cryogenic helium gas. Different designs on how this technological challenge has been overcome are described. It is shown that stable and fast spinning can be attained for sample temperatures down to 30 K using a large cryostat developed in our laboratory. Using this cryostat to cool a closed-loop of helium gas brings the additional advantage of sample spinning frequencies that can greatly surpass those achievable with nitrogen gas, due to the differing fluidic properties of these two gases. It is shown that using ultra-low temperatures for MAS-DNP results in substantial experimental sensitivity enhancements and according time-savings. Access to this temperature range is demonstrated to be both viable and highly pertinent.

  9. Carbon monoxide oxidation on Pt single crystal electrodes: understanding the catalysis for low temperature fuel cells.

    Science.gov (United States)

    García, Gonzalo; Koper, Marc T M

    2011-08-01

    Herein the general concepts of fuel cells are discussed, with special attention to low temperature fuel cells working in alkaline media. Alkaline low temperature fuel cells could well be one of the energy sources in the next future. This technology has the potential to provide power to portable devices, transportation and stationary sectors. With the aim to solve the principal catalytic problems at the anode of low temperature fuel cells, a fundamental study of the mechanism and kinetics of carbon monoxide as well as water dissociation on stepped platinum surfaces in alkaline medium is discussed and compared with those in acidic media. Furthermore, cations involved as promoters for catalytic surface reactions are also considered. Therefore, the aim of the present work is not only to provide the new fundamental advances in the electrocatalysis field, but also to understand the reactions occurring at fuel cell catalysts, which may help to improve the fabrication of novel electrodes in order to enhance the performance and to decrease the cost of low temperature fuel cells.

  10. Self-supported interconnected Pt nanoassemblies as highly stable electrocatalysts for low-temperature fuel cells.

    Science.gov (United States)

    Xia, Bao Yu; Ng, Wan Theng; Wu, Hao Bin; Wang, Xin; Lou, Xiong Wen David

    2012-07-16

    In it for the long haul: Clusters of Pt nanowires (3D Pt nanoassemblies, Pt NA) serve as an electrocatalyst for low-temperature fuel cells. These Pt nanoassemblies exhibit remarkably high stability following thousands of voltage cycles and good catalytic activity, when compared with a commercial Pt catalyst and 20 % wt Pt catalyst supported on carbon black (20 % Pt/CB).

  11. Synergy of Lewis and Brønsted acids on catalytic hydrothermal decomposition of carbohydrates and corncob acid hydrolysis residues to 5-hydroxymethylfurfural.

    Science.gov (United States)

    Wang, Chao; Zhang, Liming; Zhou, Tian; Chen, Jiachuan; Xu, Feng

    2017-01-13

    5-hydroxymethylfurfural (HMF) is an important platform molecule in the synthesis of various chemicals and materials. Herein, we reported a simple and effective dehydration of glucose-based carbohydrates to HMF in a biphasic system containing cyclopentyl methyl ether as the organic phase and AlCl3 with minute amounts of HCl as co-catalysts. The results showed that the mixed catalysts had a positive synergistic catalytic effect on glucose conversion to HMF compared with single AlCl3 or HCl catalyst. For glucose, the highest HMF yield of 54.5% was achieved at 175 °C for 20 min. More importantly, the optimal catalytic system was so efficient that it achieved one of the highest reported yields of HMF (30.5%) directly from corncob acid hydrolysis residues. Thus, the catalytic system can become a promising route for effective utilization of biomass in future biorefineries.

  12. The science capability of the Low Temperature Microgravity Physics Facility

    Science.gov (United States)

    Larson, M.; Croonquist, A.; Dick, G. J.; Liu, Y.

    2002-01-01

    The Low Temperature Microgravity Physics Facility (LTMPF) is a multiple user and multiple-flight NASA facility that will provide a low temperature environment for about 4. 5 months on board the International Space Station (ISS).

  13. HTPro: Low-temperature Surface Hardening of Stainless Steel

    DEFF Research Database (Denmark)

    Christiansen, Thomas Lundin; Somers, Marcel A. J.

    2013-01-01

    Low-temperature surface hardening of stainless steel provides the required performance properties without affecting corrosion resistance.......Low-temperature surface hardening of stainless steel provides the required performance properties without affecting corrosion resistance....

  14. Modeling Low-temperature Geochemical Processes

    Science.gov (United States)

    Nordstrom, D. K.

    2003-12-01

    Geochemical modeling has become a popular and useful tool for a wide number of applications from research on the fundamental processes of water-rock interactions to regulatory requirements and decisions regarding permits for industrial and hazardous wastes. In low-temperature environments, generally thought of as those in the temperature range of 0-100 °C and close to atmospheric pressure (1 atm=1.01325 bar=101,325 Pa), complex hydrobiogeochemical reactions participate in an array of interconnected processes that affect us, and that, in turn, we affect. Understanding these complex processes often requires tools that are sufficiently sophisticated to portray multicomponent, multiphase chemical reactions yet transparent enough to reveal the main driving forces. Geochemical models are such tools. The major processes that they are required to model include mineral dissolution and precipitation; aqueous inorganic speciation and complexation; solute adsorption and desorption; ion exchange; oxidation-reduction; or redox; transformations; gas uptake or production; organic matter speciation and complexation; evaporation; dilution; water mixing; reaction during fluid flow; reaction involving biotic interactions; and photoreaction. These processes occur in rain, snow, fog, dry atmosphere, soils, bedrock weathering, streams, rivers, lakes, groundwaters, estuaries, brines, and diagenetic environments. Geochemical modeling attempts to understand the redistribution of elements and compounds, through anthropogenic and natural means, for a large range of scale from nanometer to global. "Aqueous geochemistry" and "environmental geochemistry" are often used interchangeably with "low-temperature geochemistry" to emphasize hydrologic or environmental objectives.Recognition of the strategy or philosophy behind the use of geochemical modeling is not often discussed or explicitly described. Plummer (1984, 1992) and Parkhurst and Plummer (1993) compare and contrast two approaches for

  15. Magnetic structure at low temperatures in FeGe2

    Science.gov (United States)

    Babu, P. D.; Mishra, P. K.; Dube, V.; Mishra, R.; Sastry, P. U.; Ravikumar, G.

    2014-04-01

    Magnetic phase of FeGe2 intermetallic is studied using low-temperature neutron diffraction and DC magnetization. Zero-magnetic-field neutron scattering data shows the presence of an antiferromagnetic phase in the low temperature range. We find the evidence of the presence of a ferromagnetic order overriding on the predominantly antiferromagnetic phase at low temperatures.

  16. Low temperature nitrogen chemistry. Final report

    Energy Technology Data Exchange (ETDEWEB)

    Glarborg, P.; Dam-Johansen, K.; Kristensen, P.G.; Alzueta, M.; Roejel, H.

    1997-04-01

    The results of a two tasks program on Natural Gas Reburning are reported. The work involved an experimental and theoretical study of the reburning and hybrid reburning/SNCR chemistry in the 1000-1500 K range. The interactions between hydrocarbon and nitrogen chemistry under fuel-rich conditions were investigated in order to assess the NO{sub x} reduction potential of low temperature reburning. The effect of reburn fuel(carbon monoxide, methane, acetylene, ethylene, ethane, and methane/ethane mixture), temperature, stoichiometry, reactant dilution, reaction time, and inlet NO level were studied. The results indicate a significant NO reduction potential even below 1400 K, but extrapolation to practical conditions are complicated by inadequate knowledge of the detailed chemistry as well as of the effect of mixing. The possibilities of enhancing the conversion to N{sub 2} instead of NO by adding selective reducing agents (hybrid reburning/SNCR) were evaluated. Our results indicate little synergistic effect between reburn and SNCR. The most simple configuration, where the selective reducing agent is injected together with the burnout air, is not expected to be effective, unless the N-agent is injected in form of an aqueous solution. A chemical kinetic model for reburning and reburn/SNCR is listed and can be obtained by e-mail from pgl(commerical at)kt.dtu.dk.(au) 145 refs.

  17. Low temperature surface conductivity of hydrogenated diamond

    Energy Technology Data Exchange (ETDEWEB)

    Sauerer, C.; Ertl, F.; Nebel, C.E.; Stutzmann, M. [Technische Univ. Muenchen, Garching (Germany). Walter-Schottky-Inst. fuer Physikalische Grundlagen der Halbleiterelektronik; Bergonzo, P. [LIST(CEA-Recherche Technology)/DIMIR/SIAR/Saclay, Gif-sur-Yvette (France); Williams, O.A.; Jackman, R.A. [University Coll., London (United Kingdom). Dept. of Electrical and Electronic Engineering

    2001-07-23

    Conductivity and Hall experiments are performed on hydrogenated poly-CVD, atomically flat homoepitaxially grown Ib and natural type IIa diamond layers in the regime 0.34 to 400 K. For all experiments hole transport is detected with sheet resistivities at room temperature in the range 10{sup 4} to 10{sup 5} {omega}/{radical}. We introduce a transport model where a disorder induced tail of localized states traps holes at very low temperatures (T < 70 K). The characteristic energy of the tail is in the range of 6 meV. Towards higher temperatures (T > 70 K) the hole density is approximately constant and the hole mobility {mu} is increasing two orders of magnitude. In the regime 70 K < T < 200 K, {mu} is exponentially activated with 22 meV, above it follows a {proportional_to}T{sup 3/2} law. The activation energy of the hole density at T < 70 K is governed by the energy gap between holes trapped in the tail and the mobility edge which they can propagate. In the temperature regime T < 25 K an increasing hole mobility is detected which is attributed to transport in delocalized states at the surface. (orig.)

  18. Earthquake, strong tide and global low temperature

    Institute of Scientific and Technical Information of China (English)

    2005-01-01

    "La Madre" is a kind of upper atmospheric air current, and occurs as "warm phase" and "cold phase" in the sky of Pacific Ocean alternately. There exists this phenomenon, called "Oscillation Decade in the Pacific" (ODP), for 20~30years. It is concerned with 60 year cycle of the tides. Lunar oscillations explain an intriguing 60-year cycle in the world's temperature. Strong tides increase the vertical mixing of water in the oceans, drawing cold ocean water from the depths to surface, where it cools the atmosphere above. The first strong seismic episode in China was from 1897 to 1912; the second to the fifth was the in1920-1937, 1946-1957, 1966-1980, 1991-2002, tsrectruely. The alternative boundaries of"La Madre" warm phase and cold phase were in 1890, 1924, 1946 and 2000, which were near the boundaries of four strong earthquakes. It indicated the strong earthquakes closedly related with the substances' motion of atmosphere, hydrosphere and lithosphere, the change of gravity potential, and the exchange of angular momentum. The strong earthquakes in the ocean bottom can bring the cool waters at the deep ocean up to the ocean surface and make the global climate cold. the earthquake, strong tide and global low temperature are close inrelntion for each othen.

  19. a Low Temperature Regenerator Test Facility

    Science.gov (United States)

    Kashani, A.; Helvensteijn, B. P. M.; Feller, J. R.; Salerno, L. J.; Kittel, P.

    2008-03-01

    Testing regenerators presents an interesting challenge. When incorporated into a cryocooler, a regenerator is intimately coupled to the other components: expander, heat exchangers, and compressor. It is difficult to isolate the performance of any single component. We have developed a low temperature test facility that will allow us to separate the performance of the regenerator from the rest of the cryocooler. The purpose of the facility is the characterization of test regenerators using novel materials and/or geometries in temperature ranges down to 15 K. It consists of the following elements: The test column has two regenerators stacked in series. The coldest stage regenerator is the device under test. The warmer stage regenerator contains a stack of stainless steel screen, a well-characterized material. A commercial cryocooler is used to fix the temperatures at both ends of the test regenerator, cooling both heat exchangers flanging the regenerator stack. Heaters allow varying the temperatures and allow measurement of the remaining cooling power, and thus, regenerator effectiveness. A linear compressor delivers an oscillating pressure to the regenerator assembly. An inertance tube and reservoir provide the proper phase difference between mass flow and pressure. This phase shift, along with the imposed temperature differential, simulates the conditions of the test regenerator when used in an actual pulse tube cryocooler. This paper presents development details of the regenerator test facility, and test results on a second stage, stainless steel screen test regenerator.

  20. 不同方法制备的Cu/HZSM-5催化剂上NO的催化分解反应%Catalytic decomposition of nitrogen oxide over Cu/HZSM-5 catalysts prepared by different methods

    Institute of Scientific and Technical Information of China (English)

    阳鹏飞; 周继承; 任文明

    2011-01-01

    采用离子交换法、固相分散法和微波固相法等不同方法制备了Cu/HZSM-5催化剂,以BET、XRD和XPS等手段对催化剂样品进行了表征.结果表明,不同方法制备的Cu/HZSM-5催化剂上Cu物种的落位分布状态不同,离子交换法制备的催化剂Cu物种更多地落位于分子筛孔道内,微波固相法和固相分散法制备的催化剂Cu物种较多地落位分布在分子筛外表面.固相分散法制备的样品未能使铜物种完全分散于分子筛表面,在13.1°、16.8°、35.5°和38.0°等处仍存在CuO的晶相衍射峰.催化分解NO反应的活性考察结果表明,用微波固相法制备的催化剂催化分解NO的活性及稳定性明显超过另两种方法所制备的催化剂,在无氧条件下NO最初转化率高达89.2%,经反应25h后,转化率仍维持在70%以上;在富氧气氛下催化分解NO活性降低速率低于由离子交换法制备的催化剂.结合表征结果可以得出,落位于分子筛外表面以离子交换态形式存在的Cu物种对催化分解NO反应更为有利,而且催化稳定性更好.%Cu/HZSM-5 catalysts were prepared by different methods of ion exchange, solid-state dispersion and solid-state microwave irradiation. The obtained Cu/HZSM-5 catalysts were characterized by means of BET,XRD and XPS. Experimental results exhibited that the location of Cu species was strongly dependent on the preparation method. Cu species on the external surface of the zeolite prepared by solid-state microwave irradiation and solid-state dispersion are more than ion exchange. And the crystalline diffraction peaks of CuO species can be found in the samples prepared by solid-state dispersion. In addition, the catalytic performance of the catalyst for NO catalytic decomposition was investigated. Compared with the other two methods, the catalysts prepared by solide-state microwave irradiation showed higher catalytic activity and stability for NO catalytic decomposition. Under anaerobic

  1. Low Temperature Surface Carburization of Stainless Steels

    Energy Technology Data Exchange (ETDEWEB)

    Collins, Sunniva R; Heuer, Arthur H; Sikka, Vinod K

    2007-12-07

    Low-temperature colossal supersaturation (LTCSS) is a novel surface hardening method for carburization of austenitic stainless steels (SS) without the precipitation of carbides. The formation of carbides is kinetically suppressed, enabling extremely high or colossal carbon supersaturation. As a result, surface carbon concentrations in excess of 12 at. % are routinely achieved. This treatment increases the surface hardness by a factor of four to five, improving resistance to wear, corrosion, and fatigue, with significant retained ductility. LTCSS is a diffusional surface hardening process that provides a uniform and conformal hardened gradient surface with no risk of delamination or peeling. The treatment retains the austenitic phase and is completely non-magnetic. In addition, because parts are treated at low temperature, they do not distort or change dimensions. During this treatment, carbon diffusion proceeds into the metal at temperatures that constrain substitutional diffusion or mobility between the metal alloy elements. Though immobilized and unable to assemble to form carbides, chromium and similar alloying elements nonetheless draw enormous amounts of carbon into their interstitial spaces. The carbon in the interstitial spaces of the alloy crystals makes the surface harder than ever achieved before by more conventional heat treating or diffusion process. The carbon solid solution manifests a Vickers hardness often exceeding 1000 HV (equivalent to 70 HRC). This project objective was to extend the LTCSS treatment to other austenitic alloys, and to quantify improvements in fatigue, corrosion, and wear resistance. Highlights from the research include the following: • Extension of the applicability of the LTCSS process to a broad range of austenitic and duplex grades of steels • Demonstration of LTCSS ability for a variety of different component shapes and sizes • Detailed microstructural characterization of LTCSS-treated samples of 316L and other alloys

  2. Low-temperature gas from marine shales: wet gas to dry gas over experimental time

    Directory of Open Access Journals (Sweden)

    Jarvie Daniel M

    2009-11-01

    Full Text Available Abstract Marine shales exhibit unusual behavior at low temperatures under anoxic gas flow. They generate catalytic gas 300° below thermal cracking temperatures, discontinuously in aperiodic episodes, and lose these properties on exposure to trace amounts of oxygen. Here we report a surprising reversal in hydrocarbon generation. Heavy hydrocarbons are formed before light hydrocarbons resulting in wet gas at the onset of generation grading to dryer gas over time. The effect is moderate under gas flow and substantial in closed reactions. In sequential closed reactions at 100°C, gas from a Cretaceous Mowry shale progresses from predominately heavy hydrocarbons (66% C5, 2% C1 to predominantly light hydrocarbons (56% C1, 8% C5, the opposite of that expected from desorption of preexisting hydrocarbons. Differences in catalyst substrate composition explain these dynamics. Gas flow should carry heavier hydrocarbons to catalytic sites, in contrast to static conditions where catalytic sites are limited to in-place hydrocarbons. In-place hydrocarbons and their products should become lighter with conversion thus generating lighter hydrocarbon over time, consistent with our experimental results. We recognize the similarities between low-temperature gas generation reported here and the natural progression of wet gas to dry gas over geologic time. There is now substantial evidence for natural catalytic activity in source rocks. Natural gas at thermodynamic equilibrium and the results reported here add to that evidence. Natural catalysis provides a plausible and unique explanation for the origin and evolution of gas in sedimentary basins.

  3. An operando optical fiber UV–vis spectroscopic study of the catalytic decomposition of NO and N2O over Cu-ZSM-5

    NARCIS (Netherlands)

    Weckhuysen, B.M.; Groothaert, M.H.; Lievens, K.; Leeman, H.; Schoonheydt, R.A.

    2003-01-01

    The role of the bis(μ-oxo)dicopper core, i.e., [Cu2(μ-O)2]2+, in the decomposition of NO and N2O by the Cu-ZSM-5 zeolite has been studied with combined operando UV–vis monitoring of the catalyst and on-line GC analysis. An optical fiber was mounted on the outer surface of the quartz wall of the

  4. An operando optical fiber UV–vis spectroscopic study of the catalytic decomposition of NO and N2O over Cu-ZSM-5

    NARCIS (Netherlands)

    Weckhuysen, B.M.; Groothaert, M.H.; Lievens, K.; Leeman, H.; Schoonheydt, R.A.

    2003-01-01

    The role of the bis(μ-oxo)dicopper core, i.e., [Cu2(μ-O)2]2+, in the decomposition of NO and N2O by the Cu-ZSM-5 zeolite has been studied with combined operando UV–vis monitoring of the catalyst and on-line GC analysis. An optical fiber was mounted on the outer surface of the quartz wall of the plug

  5. Comparison of the Effects of Fluidized-Bed and Fixed-Bed Reactors in Microwave-Assisted Catalytic Decomposition of TCE by Hydrogen

    Directory of Open Access Journals (Sweden)

    Lili Ren

    2012-01-01

    Full Text Available Trichloroethylene (TCE decomposition by hydrogen with microwave heating under different reaction systems was investigated. The activities of a series of catalysts for microwave-assisted TCE hydrodechlorination were tested through the fixed-bed and the fluidized-bed reactor systems. This study found that the different reaction system is suitable for different catalyst type. And there is an interactive relationship between the catalyst type and the reaction bed type.

  6. Systemic low temperature signaling in Arabidopsis.

    Science.gov (United States)

    Gorsuch, Peter A; Sargeant, Alexander W; Penfield, Steven D; Quick, W Paul; Atkin, Owen K

    2010-09-01

    When leaves are exposed to low temperature, sugars accumulate and transcription factors in the C-repeat binding factor (CBF) family are expressed, which, together with CBF-independent pathways, are known to contribute to the cold acclimation process and an increase in freezing tolerance. What is not known, however, is whether expression of these cold-regulated genes can be induced systemically in response to a localized cold treatment. To address this, pre-existing, mature leaves of warm-grown Arabidopsis thaliana were exposed to a localized cold treatment (near 10 °C) whilst conjoined newly developing leaves continued only to experience warmer temperatures. In initial experiments on wild-type A. thaliana (Col-0) using real-time reverse transcription--PCR (RT-PCR) we observed that some genes--including CBF genes, certain downstream cold-responsive (COR) targets and CBF-independent transcription factors--respond to a direct 9 °C treatment of whole plants. In subsequent experiments, we found that the treatment of expanded leaves with temperatures near 10 °C can induce cold-associated genes in conjoined warm-maintained tissues. CBF1 showed a particularly strong systemic response, although CBF-independent transcription factors also responded. Moreover, the localized cold treatment of A. thaliana (C24) plants with a luciferase reporter fused to the promoter region of KIN2 indicated that in warm-maintained leaves, KIN2 might respond to a systemic signal from remote, directly cold-treated leaves. Collectively, our study provides strong evidence that the processes involved in cold acclimation are partially mediated by a signal that acts systemically. This has the potential to act as an early-warning system to enable developing leaves to cope better with the cold environment in which they are growing.

  7. Development of a hydrophilic interaction liquid chromatography-mass spectrometry method for detection and quantification of urea thermal decomposition by-products in emission from diesel engine employing selective catalytic reduction technology.

    Science.gov (United States)

    Yassine, Mahmoud M; Dabek-Zlotorzynska, Ewa; Celo, Valbona

    2012-03-16

    The use of urea based selective catalytic reduction (SCR) technology for the reduction of NOx from the exhaust of diesel-powered vehicles has the potential to emit at least six thermal decomposition by-products, ammonia, and unreacted urea from the tailpipe. These compounds may include: biuret, dicyandiamine, cyanuric acid, ammelide, ammeline and melamine. In the present study, a simple, sensitive and reliable hydrophilic interaction liquid chromatography (HILIC)-electrospray ionization (ESI)/mass spectrometry (MS) method without complex sample pre-treatment was developed for identification and determination of urea decomposition by-products in diesel exhaust. Gradient separation was performed on a SeQuant ZIC-HILIC column with a highly polar zwitterionic stationary phase, and using a mobile phase consisting of acetonitrile (eluent A) and 15 mM ammonium formate (pH 6; eluent B). Detection and quantification were performed using a quadrupole ESI/MS operated simultaneously in negative and positive mode. With 10 μL injection volume, LODs for all target analytes were in the range of 0.2-3 μg/L. The method showed a good inter-day precision of retention time (RSDfilter (DPF) and urea based SCR technology showed the presence of five target analytes with cyanuric acid and ammelide the most abundant compounds in the exhaust.

  8. FY 1998 annual report on the decomposition/removal of harmful compounds in the gaseous phase by porous membrane provided with a catalytic function; 1998 nendo shokubai kinotsuki fuyo takomaku ni yoru kisochu yugai busshitsu no bunkai jokyo chosa hokokusho

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1999-03-01

    Harmful compounds, e.g., dioxins and nitrogen oxides, released into the air are causing severer environmental problems on a global scale. In order to solve these problems, it is necessary to efficiently remove the released compounds in the vicinity of the living environments, while preventing, as far as possible, their formation at the sources. An attempt has been made to develop porous membranes impregnated with composites of a variety of metallic oxides showing activities as photocatalysts and for dark reactions by the ion engineering method, in order to drastically solve the above problems. Described herein are the FY 1998 results. Thin films of various titanium oxide crystals (anatase, rutile, and their combinations) are formed on Si substrates by the ion engineering method, as the photocatalysts for decomposition of aldehyde and water (for hydrogen production), to validate the optimum crystalline structures for the photocatalysis. Porous bodies of Ni and carbon are also impregnated with anatase TiO{sub 2} for decomposition of harmful gaseous compounds and water, to validate the effects of the porous membranes provided with catalytic functions. (NEDO)

  9. Synthesis of CuO porous nanorods and their catalytic activity in the decomposition of potassium chlorate and peroxide%孔状氧化铜纳米棒的制备及其催化性能研究

    Institute of Scientific and Technical Information of China (English)

    徐惠; 黄剑; 陈泳

    2011-01-01

    Copper monoxide (CUO) porous nanorods of 100-200nm in diameter and 2-3μm in length were successfully synthesized using a hydrothermal reaction method in the presence of urea. The products were characterized by SEM., TEM, FT-IR, XRD and TG analysis techniques. The results of catalytic activity indicate that CuO nanocrystal promoted potassium chlorate and peroxide decomposition. When the ratio of H2O2 to CuP is 5 to 1,the decomposition of peroxide is perfect.%以硝酸铜为铜源,采用尿素矿化剂,通过水热法制得纳米氧化铜前驱体,高温煅烧后得到长21μm,直径200nm的氧化铜多孔纳米捧,所得产品尺寸均一,微孔分布均匀,排列整齐.通过IR、XRD、SEM以及TEM对其结构和形貌进行了表征.研究表明,所制备的纳米氧化铜多孔棒无需任何制样处理对氯酸钾和过氧化氢具有较高的催化活性,当n(H2O2):n(CuO)=5:1时,过氧化氢的分解速率最快.

  10. Composite Materials for Low-Temperature Applications

    Science.gov (United States)

    2008-01-01

    Composite materials with improved thermal conductivity and good mechanical strength properties should allow for the design and construction of more thermally efficient components (such as pipes and valves) for use in fluid-processing systems. These materials should have wide application in any number of systems, including ground support equipment (GSE), lunar systems, and flight hardware that need reduced heat transfer. Researchers from the Polymer Science and Technology Laboratory and the Cryogenics Laboratory at Kennedy Space Center were able to develop a new series of composite materials that can meet NASA's needs for lightweight materials/composites for use in fluid systems and also expand the plastic-additive markets. With respect to thermal conductivity and physical properties, these materials are excellent alternatives to prior composite materials and can be used in the aerospace, automotive, military, electronics, food-packaging, and textile markets. One specific application of the polymeric composition is for use in tanks, pipes, valves, structural supports, and components for hot or cold fluid-processing systems where heat flow through materials is a problem to be avoided. These materials can also substitute for metals in cryogenic and other low-temperature applications. These organic/inorganic polymeric composite materials were invented with significant reduction in heat transfer properties. Decreases of 20 to 50 percent in thermal conductivity versus that of the unmodified polymer matrix were measured. These novel composite materials also maintain mechanical properties of the unmodified polymer matrix. These composite materials consist of an inorganic additive combined with a thermoplastic polymer material. The intrinsic, low thermal conductivity of the additive is imparted into the thermoplastic, resulting in a significant reduction in heat transfer over that of the base polymer itself, yet maintaining most of the polymer's original properties. Normal

  11. Preparation of nanometer NiO/MgO and its catalytic performance for thermal decomposition of ammonium perchlorate%纳米NiO/MgO的制备及其对AP热分解催化性能影响

    Institute of Scientific and Technical Information of China (English)

    谈玲华; 李勤华; 杭祖圣; 潘仁明; 姜炜; 李凤生

    2011-01-01

    采用浸渍法制备出纳米NiO/MgO复合氧化物粒子,运用X射线衍射(XRD)、X射线能谱仪(EDS)等对产物的物相和组成进行了表征,并研究了单一纳米粒子(NiO、MgO)、纳米NiO+MgO混合粒子及纳米NiO/MgO复合氧化物粒子对AP热分解的催化性能.结果表明,所制备的纳米NiO/MgO复合氧化物粒子中NiO粒子高度分散于MgO载体中.纳米NiO/MgO复合氧化物粒子可使AP的高温分解峰温降低92.2℃,高低温分解峰温差减小到10.6℃,表现出较强的催化性能,其催化性能优于单一纳米粒子(NiO、MgO)、纳米NiO+MgO混合粒子.纳米MgO的载体支撑作用,可防止NiO纳米粒子的团聚,增加反应活性中心,从而提高催化效果.%The nanometer NiO/MgO composite particles were prepared via impregnation method. The phase and morphology of NiO/MgO composites were characterized by X-ray diffraction, transmission electron microscopy and energy dispersive X-Ray spectroscopy. The catalysis of nanometer particles ( NiO, MgO), NiO + MgO mixture particles and NiO/MgO composite particles the thermal decomposition of ammonium perchlorate (AP) was investigated by DSC. The Results show that NiO particles are highly dispersed on the MgO support. Catalytic performance of the obtained nanometer NiO/MgO composite particles is superior to that of corresponding single ingredient and NiO + MgO mixture particles. Nanometer NiO/MgO can make the high-temperature decomposition peak value of AP decrease by 92.2 ℃ and the temperature difference value between the low and high temperature decomposition peak reduce up to 10. 6 ℃, which indicates good catalytic performance. The supporting effect of the nanometer MgO can effectively prevent the aggregation of NiO particles and increase the active sites.

  12. Low Temperature Surface Carburization of Stainless Steels

    Energy Technology Data Exchange (ETDEWEB)

    Collins, Sunniva R; Heuer, Arthur H; Sikka, Vinod K

    2007-12-07

    Low-temperature colossal supersaturation (LTCSS) is a novel surface hardening method for carburization of austenitic stainless steels (SS) without the precipitation of carbides. The formation of carbides is kinetically suppressed, enabling extremely high or colossal carbon supersaturation. As a result, surface carbon concentrations in excess of 12 at. % are routinely achieved. This treatment increases the surface hardness by a factor of four to five, improving resistance to wear, corrosion, and fatigue, with significant retained ductility. LTCSS is a diffusional surface hardening process that provides a uniform and conformal hardened gradient surface with no risk of delamination or peeling. The treatment retains the austenitic phase and is completely non-magnetic. In addition, because parts are treated at low temperature, they do not distort or change dimensions. During this treatment, carbon diffusion proceeds into the metal at temperatures that constrain substitutional diffusion or mobility between the metal alloy elements. Though immobilized and unable to assemble to form carbides, chromium and similar alloying elements nonetheless draw enormous amounts of carbon into their interstitial spaces. The carbon in the interstitial spaces of the alloy crystals makes the surface harder than ever achieved before by more conventional heat treating or diffusion process. The carbon solid solution manifests a Vickers hardness often exceeding 1000 HV (equivalent to 70 HRC). This project objective was to extend the LTCSS treatment to other austenitic alloys, and to quantify improvements in fatigue, corrosion, and wear resistance. Highlights from the research include the following: • Extension of the applicability of the LTCSS process to a broad range of austenitic and duplex grades of steels • Demonstration of LTCSS ability for a variety of different component shapes and sizes • Detailed microstructural characterization of LTCSS-treated samples of 316L and other alloys

  13. Decomposição catalítica de óxidos de nitrogênio Catalytic decomposition of nitrogen oxides

    Directory of Open Access Journals (Sweden)

    Julia María Díaz Cónsul

    2004-06-01

    Full Text Available Contaminant gases in the atmosphere constitute an important problem to be solved in the world. The NOx gases produced as a consequence of engine high temperatures are deleterious to environment and human health, as they promote acid rain and can act in the same way as freons in the destruction of the ozone layer in the stratosphere. In this review, three way and selective reduction catalysts for decomposition of these contaminant gases are described. Details about conditions and problems, such as catalyst poisoning, and the search for new catalysts are shown.

  14. 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.

  15. Low temperature environmental degradation of zirconia ceramics

    Science.gov (United States)

    Zhao, Zhenbo

    2005-11-01

    The low temperature environmental degradation (LTED) of yttria-stabilized tetragonal zirconia polycrystal (Y-TZP) has been prevented, or at least retarded, by using both bulk doping and surface doping methods with either cation, or anion, stabilizers. The introduction of both mullite and alumina into 3Y-TZP by a bulk-doping method was found to be effective in suppressing the tetragonal-->monoclinic transformation induced by water during hydrothermal treatment thus giving rise to better mechanical properties. The beneficial effects of alumina on the phase stability of the 3Y-TZP ceramic are considered to be due to the increase in the elastic modulus of the constraining matrix, as well as to the segregation of A12O3 at grain boundaries. The LTED transformation kinetics as determined by x-ray diffraction (XRD) and White Light Interferometer (WLI) analysis showed that the isothermal tetragonal-to-monoclinic transformation starts from the surface and has an incubation-nucleation-growth mechanism which can be described by the Johnson-Mehl-Avrami equation. The degradation of Y-TZP ceramic after hydrothermal treatment can be effectively overcome by surface doping by a solid diffusion method with tetravalent dopants: CeO2 and GeO2; with trivalent dopants: La2O 3 and Fe2O3; and with divalent dopants: CuO and MgO. For surface CeO2-, GeO2- and Fe2O 3-doping, this degradation inhibition behaviour is attributed to a localized increase in cation stabilizer content which satisfies the requirements for stabilization of the tetragonal phase. However, in each case, the stability mechanisms are different. For surface La2O3doping, surface doping overcomes the formation of La2O3 and La 2Zr2O7 since the extra La2O3 can further diffuse to the center of the 3Y-TZP ceramic. For CuO-doping, small amounts of CuO form a liquid that can act as a conduit for the re-distribution of yttria. In the case of surface MgO modification, the stabilization results from the isolated nature of the

  16. Characterization and catalytic behavior of MoO3/V2O5/Nb2 O5 systems in isopropanol decomposition

    Directory of Open Access Journals (Sweden)

    J. B. de Paiva Jr

    2006-12-01

    Full Text Available The influence of molybdenum oxide as a promoter on the V2O5/Nb2O5 system was investigated. A series of MoO3/V2O5/Nb2 O5 catalysts, with MoO3 loading ranging from 1 to 3 wt% MoO3 and fixed V2O5 content (21 wt%, were prepared by impregnation of the Nb2O5 support with an aqueous solution of ammonium metavanadate and ammonium molybdate. The acid-base properties of the catalysts were investigated to determine of the selectivity of the isopropanol decomposition reaction. The X-ray diffraction results showed the presence of the beta-(Nb,V2O5 phase. The temperature-programmed reduction profiles showed that the reducibility of vanadium was affected by the presence of molybdenum oxide. Activity results for isopropanol decomposition revealed that the acid-base properties of V2O5/Nb2O5 catalysts are affected upon incorporation of MoO3, specifically for loadings of 3 wt %. For this catalyst composition both propylene and acetone formation rates decreased.

  17. Li-Ion Cell Development for Low Temperature Applications

    Science.gov (United States)

    Huang, C.-K.; Sakamoto, J. S.; Surampudi, S.; Wolfenstine, J.

    2000-01-01

    JPL is involved in the development of rechargeable Li-ion cells for future Mars Exploration Missions. The specific objectives are to improve the Li-ion cell cycle life performance and rate capability at low temperature (Li-ion rate capability at low temperature has been attributed to: (1) the electrolytes becoming viscous or freezing and/or (2) reduced electrode capacity that results from decreased Li diffusivity. Our efforts focus on increasing the rate capability at low temperature for Li-ion cells. In order to improve the rate capability we evaluated the following: (1) cathode performance at low temperatures, (2) electrode active material particle size on low temperature performance and (3) Li diffusivity at room temperature and low temperatures. In this paper, we will discuss the results of our study.

  18. Effectiveness of Low Temperature Additives for Biodiesel Blends

    Science.gov (United States)

    2012-06-30

    UNCLASSIFIED EFFECTIVENESS OF LOW TEMPERATURE ADDITIVES FOR BIODIESEL BLENDS INTERIM REPORT TFLRF No. 428 by Steven R...Do not return it to the originator. UNCLASSIFIED UNCLASSIFIED EFFECTIVENESS OF LOW TEMPERATURE ADDITIVES FOR BIODIESEL BLENDS...17-2010 – 06-30-2012 4. TITLE AND SUBTITLE Effectiveness of Low Temperature Additives for Biodiesel Blends 5a. CONTRACT NUMBER W56HZV-09-C-0100

  19. 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.

  20. Cryogenic Capacitors for Low-Temperature Power Systems Project

    Data.gov (United States)

    National Aeronautics and Space Administration — TRS Technologies proposes to develop low-temperature multilayer ceramic capacitors (MLCCs) capable of operating at cyrogenic temperatures (<77K). These capacitors...

  1. Low-temperature Hall effect in bismuth chalcogenides thin films

    Science.gov (United States)

    Kuntsevich, A. Yu.; Gabdullin, A. A.; Prudkogliad, V. A.; Selivanov, Yu. G.; Chizhevskii, E. G.; Pudalov, V. M.

    2016-12-01

    Bismuth chalcogenides are the most studied 3D topological insulators. As a rule, at low temperatures, thin films of these materials demonstrate positive magnetoresistance due to weak antilocalization. Weak antilocalization should lead to resistivity decrease at low temperatures; in experiments, however, resistivity grows as temperature decreases. From transport measurements for several thin films (with various carrier density, thickness, and carrier mobility), and by using a purely phenomenological approach, with no microscopic theory, we show that the low-temperature growth of the resistivity is accompanied by growth of the Hall coefficient, in agreement with the diffusive electron-electron interaction correction mechanism. Our data reasonably explain the low-temperature resistivity upturn.

  2. Surface characterization studies on the interaction of V{sub 2}O{sub 5}–WO{sub 3}/TiO{sub 2} catalyst for low temperature SCR of NO with NH{sub 3}

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Shule; Zhong, Qin, E-mail: zq304@mail.njust.edu.cn

    2015-01-15

    This study aimed at elucidating the surface characterization of V{sub 2}O{sub 5}–WO{sub 3}/TiO{sub 2} catalyst to investigate the interaction of V, W and Ti species for the improvement of the catalytic activity in the SCR reaction at low-temperature. Analysis by XRD, UV–vis, PL spectra and DFT theoretical calculations, XPS, EPR and in situ DRIFT showed that WO{sub 3} could interact with TiO{sub 2} to improve the electrons transfer, and the WO{sub 3} hybridization with V{sub 2}O{sub 5} could also improve the reducibility and formation of reduced V{sub 2}O{sub 5} species for the V{sub 2}O{sub 5}–WO{sub 3}/TiO{sub 2} catalyst. These aspects resulted in the NO oxidation and NO{sub 3}{sup −} decomposition that were responsible for the high catalytic activity of V{sub 2}O{sub 5}–WO{sub 3}/TiO{sub 2} catalyst. - Graphical abstract: Interaction of V, W and Ti species improved the formation of reduced V{sub 2}O{sub 5} and O{sub 2}{sup −}, NO oxidation and NO{sub 3}{sup −} decomposition to enhance the catalytic activity of VWTi catalyst. - Highlights: • Interaction of V, W and Ti species improved the SCR reaction at low-temperature. • Hybridization between WO{sub 3} and V{sub 2}O{sub 5} improved the reducibility and reduced V{sub 2}O{sub 5} species formation of V{sub 2}O{sub 5}–WO{sub 3}/TiO{sub 2} catalyst. • The interaction improved the NO oxidation and NO{sub 3}{sup −} decomposition over V{sub 2}O{sub 5}–WO{sub 3}/TiO{sub 2} catalyst.

  3. Effect of calcination temperature on performance of Mn-Fe/CeO2-TiO2catalyst for selective catalytic reduction of NO by NH3 at low temperature%焙烧温度对Mn-Fe/CeO2-TiO2催化剂低温NH3选择性催化还原NO的影响

    Institute of Scientific and Technical Information of China (English)

    吴大旺; 张秋林; 林涛; 龚茂初; 陈耀强

    2012-01-01

    采用等体积浸渍法制备了Mn-Fe/CeO2-TiO2催化剂,考察了不同焙烧温度对其NH3选择性催化还原(SCR) NO活性及催化剂性能的影响.并用N2吸附-脱附,X射线衍射(XRD)和X射线光电子能谱(XPS)等手段对催化剂进行了表征.活性结果表明,随着焙烧温度的升高,Mn-Fe./CeO2-TiO2催化剂的催化活性先升高后降低.其中焙烧温度为500℃时Mn/CeO2-TiO2的NH3-SCR活性最佳,该催化剂在113 ~ 250℃之间表现出了良好NO去除效率.表征结果表明,500℃焙烧时,催化剂中Fe和Mn物种在CeO2-TiO2表面的分散效果最好.500℃焙烧时Mn-Fe/CeO2-TiO2表面Mn以+4价存在,Fe以+3、+2价存在,而Ce以+4、+3存在.%The Mn-Fe/CeO2-TiO2 catalyst was prepared by the incipient wetness method,the influence of calcination temperature on the property and catalytic activity of Mn-Fe/CeO2 -TiO2 was studied for selective catalytic reduction( SCR) of NO by NH3. The catalysts were characterized by N2-adsorption-desorption, X-ray diffraction and X-ray photoelectron spectroscopy. The performance results showed that the catalytic activities were fust increased and subsequently decreased with the increase of calcination temperature. The catalyst calcined at 500℃ showed the best activity for NO reduction by NH3, and this catalyst exhibited high NO conversion in a wide temperature range of 113-250℃. The characterization results revealed that the Mn-Fe/CeO2-TiO2 catalyst calcined at 500℃ promoted the dispersion of Mn and Fe species on CeO2-TiO2. The XPS results indicated that the Mn species was existed in a valence of +4. Fe species was existed as a mixed valence of +3 and+2 and Ce species was a mixed valence of existed as +4 and +3.

  4. 46 CFR 56.50-105 - Low-temperature piping.

    Science.gov (United States)

    2010-10-01

    ... 46 Shipping 2 2010-10-01 2010-10-01 false Low-temperature piping. 56.50-105 Section 56.50-105 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) MARINE ENGINEERING PIPING SYSTEMS AND APPURTENANCES Design Requirements Pertaining to Specific Systems § 56.50-105 Low-temperature piping. (a) Class...

  5. Low temperature magnetic force microscopy on ferromagnetic and superconducting oxides

    Science.gov (United States)

    Sirohi, Anshu; Sheet, Goutam

    2016-05-01

    We report the observation of complex ferromagnetic domain structures on thin films of SrRuO3 and superconducting vortices in high temperature superconductors through low temperature magnetic force microscopy. Here we summarize the experimental details and results of magnetic imaging at low temperatures and high magnetic fields. We discuss these data in the light of existing theoretical concepts.

  6. Low temperature barrier wellbores formed using water flushing

    Science.gov (United States)

    McKinzie, II; John, Billy [Houston, TX; Keltner, Thomas Joseph [Spring, TX

    2009-03-10

    A method of forming an opening for a low temperature well is described. The method includes drilling an opening in a formation. Water is introduced into the opening to displace drilling fluid or indigenous gas in the formation adjacent to a portion of the opening. Water is produced from the opening. A low temperature fluid is applied to the opening.

  7. Low Temperature Photoluminescence (PL) from High Electron Mobility Transistors (HEMTs)

    Science.gov (United States)

    2015-03-01

    TECHNICAL REPORT RDMR-WD-14-55 LOW TEMPERATURE PHOTOLUMINESCENCE (PL) FROM HIGH ELECTRON MOBILITY TRANSISTORS (HEMTS...DATE March 2015 3. REPORT TYPE AND DATES COVERED Final 4. TITLE AND SUBTITLE Low Temperature Photoluminescence (PL) From High Electron...temperature Photoluminescence (PL) from High Electron Mobility Transistor (HEMT) structures that have been modified by proton irradiation. The samples are

  8. The Development of the Low Temperature Microgravity Physics Facility

    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 long duration (4.5 months) low temperature (1.4K) and microgravity conditions for scientists to perform breakthrough investigations on board the International Space Station.

  9. Low temperature gaseous surface hardening of stainless steel

    DEFF Research Database (Denmark)

    Christiansen, Thomas; Somers, Marcel A. J.

    2011-01-01

    The present contribtion gives an overview of some of the technological aspects of low temperature thermochemical treatment of stainless steel. Examples of low temperature gaseous nitriding, carburising and nitrocarburising of stainless steel are presented and discussed. In particular......, the morphology, microstructure and characteristics of so-called expanded austenite "layers" on stainless steel are addressed....

  10. Low temperature gaseous surface hardening of stainless steel

    DEFF Research Database (Denmark)

    Christiansen, Thomas; Somers, Marcel A. J.

    2010-01-01

    The present contribution gives an overview of some of the technological aspects of low temperature thermochemical treatment of stainless steel. Examples of low temperature gaseous nitriding, carburising and nitrocarburising of stainless steel are presented and discussed. In particular......, the morphology, microstructure and characteristics of so-called expanite “layers” on stainless steel are addressed....

  11. Oxyhydrogen burner for low-temperature flame fusion

    Science.gov (United States)

    Ueltzen, M.; Brüggenkamp, T.; Franke, M.; Altenburg, H.

    1993-04-01

    An oxyhydrogen burner as described in this article enables the growth of crystals by Verneuil's technique at temperatures of about 1000 °C. The powder fed to the crystal passes along a low-temperature pathway through the flame, so that evaporation of volatile components is prevented. Low-temperature flame fusion of superconducting Y-Ba-cuprate is reported.

  12. Experimental and Modeling Investigation of the Low-Temperature Oxidation of Dimethyl Ether.

    Science.gov (United States)

    Rodriguez, Anne; Frottier, Ophélie; Herbinet, Olivier; Fournet, René; Bounaceur, Roda; Fittschen, Christa; Battin-Leclerc, Frédérique

    2015-07-16

    The oxidation of dimethyl ether (DME) was studied using a jet-stirred reactor over a wide range of conditions: temperatures from 500 to 1100 K; equivalence ratios of 0.25, 1, and 2; residence time of 2 s; pressure of 106.7 kPa (close to the atmospheric pressure); and an inlet fuel mole fraction of 0.02 (with high dilution in helium). Reaction products were quantified using two analysis methods: gas chromatography and continuous wave cavity ring-down spectroscopy (cw-CRDS). cw-CRDS enabled the quantification of formaldehyde, which is one of the major products from DME oxidation, as well as that of hydrogen peroxide, which is an important branching agent in low-temperature oxidation chemistry. Experimental data were compared with data computed using models from the literature with important deviations being observed for the reactivity at low-temperature. A new detailed kinetic model for the oxidation of DME was developed in this study. Kinetic parameters used in this model were taken from literature or calculated in the present work using quantum calculations. This new model enables a better prediction of the reactivity in the low-temperature region. Under the present JSR conditions, error bars on predictions were given. Simulations were also successfully compared with experimental flow reactor, jet-stirred reactor, shock tube, rapid compression machine, and flame data from literature. The kinetic analysis of the model enabled the highlighting of some specificities of the oxidation chemistry of DME: (1) the early reactivity which is observed at very low-temperature (e.g., compared to propane) is explained by the absence of inhibiting reaction of the radical directly obtained from the fuel (by H atom abstraction) with oxygen yielding an olefin + HO2·; (2) the low-temperature reactivity is driven by the relative importance of the second addition to O2 (promoting the reactivity through branching chain) and the competitive decomposition reactions with an inhibiting

  13. Involvement of metals in enzymatic and nonenzymatic decomposition of C-terminal alpha-hydroxyglycine to amide: an implication for the catalytic role of enzyme-bound zinc in the peptidylamidoglycolate lyase reaction.

    Science.gov (United States)

    Takahashi, Kenichi; Harada, Saori; Higashimoto, Yuichiro; Shimokawa, Chizu; Sato, Hideaki; Sugishima, Masakazu; Kaida, Yasuhiko; Noguchi, Masato

    2009-02-24

    The peptide C-terminal amide group essential for the full biological activity of many peptide hormones is produced by consecutive actions of peptidylglycine alpha-hydroxylating monooxygenase (PHM) and peptidylamidoglycolate lyase (PAL); PHM catalyzes the hydroxylation of C-terminal glycine, and PAL decomposes the peptidyl-alpha-hydroxyglycine to an amidated peptide and glyoxylate. PAL contains 1 mol of zinc, but its role, catalytic or structural, has not yet been clarified. In this study, we found that a series of transition metals, Mn(2+), Co(2+), Ni(2+), Cu(2+), Zn(2+), and Cd(2+), catalyze the nonenzymatic decomposition of the hydroxyglycine intermediate in a concentration-dependent manner. The second-order rate constant of the metal catalysis increased with elevation of pH, indicating that the hydrated metal acts as a general base. Extensive removal of the enzyme-bound metals remarkably diminished the PAL activity; k(cat) of the metal-depleted enzyme retaining 0.1 mol of zinc decreased to 3.2 s(-1) from 25.7 s(-1) of the wild-type enzyme. Among a series of divalent metals tested, Zn(2+), Co(2+), and Cd(2+) could fully restore the PAL activity of the metal-depleted enzyme. Especially, Zn substitution reproduced the steady-state parameters of the wild-type enzyme. On the other hand, Co and Cd substitution largely altered the kinetic parameters; the k(cat) increased 3- and 5-fold and the K(m) for the substrate increased 2.5- and 4-fold, respectively. These observations support that the enzyme-bound zinc plays a catalytic role, rather than a structural role, in the PAL reaction through the action of zinc-bound water as a general base.

  14. Synthesis of TiO₂-loaded Co0.85Se thin films with heterostructure and their enhanced catalytic activity for p-nitrophenol reduction and hydrazine hydrate decomposition.

    Science.gov (United States)

    Zuo, Yong; Song, Ji-Ming; Niu, He-Lin; Mao, Chang-Jie; Zhang, Sheng-Yi; Shen, Yu-Hua

    2016-04-08

    P-nitrophenol (4-NP) and hydrazine hydrate are considered to be highly toxic pollutants in wastewater, and it is of great importance to remove them. Herein, TiO2-loaded Co0.85Se thin films with heterostructure were successfully synthesized by a hydrothermal route. The as-synthesized samples were characterized by x-ray diffraction, x-ray photoelectron spectroscopy, transmission electron microscopy and selective-area electron diffraction. The results demonstrate that TiO2 nanoparticles with a size of about 10 nm are easily loaded on the surface of graphene-like Co0.85Se nanofilms, and the NH3 · H2O plays an important role in the generation and crystallization of TiO2 nanoparticles. Brunauer-Emmett-Teller measurement shows that the obtained nanocomposites have a larger specific surface area (199.3 m(2) g(-1)) than that of Co0.85Se nanofilms (55.17 m(2) g(-1)) and TiO2 nanoparticles (19.49 m(2) g(-1)). The catalytic tests indicate Co0.85Se-TiO2 nanofilms have the highest activity for 4-NP reduction and hydrazine hydrate decomposition within 10 min and 8 min, respectively, compared with the corresponding precursor Co0.85Se nanofilms and TiO2 nanoparticles. The enhanced catalytic performance can be attributed to the larger specific surface area and higher rate of interfacial charge transfer in the heterojunction than that of the single components. In addition, recycling tests show that the as-synthesized sample presents stable conversion efficiency for 4-NP reduction.

  15. Synthesis of TiO2-loaded Co0.85Se thin films with heterostructure and their enhanced catalytic activity for p-nitrophenol reduction and hydrazine hydrate decomposition

    Science.gov (United States)

    Zuo, Yong; Song, Ji-Ming; Niu, He-Lin; Mao, Chang-Jie; Zhang, Sheng-Yi; Shen, Yu-Hua

    2016-04-01

    P-nitrophenol (4-NP) and hydrazine hydrate are considered to be highly toxic pollutants in wastewater, and it is of great importance to remove them. Herein, TiO2-loaded Co0.85Se thin films with heterostructure were successfully synthesized by a hydrothermal route. The as-synthesized samples were characterized by x-ray diffraction, x-ray photoelectron spectroscopy, transmission electron microscopy and selective-area electron diffraction. The results demonstrate that TiO2 nanoparticles with a size of about 10 nm are easily loaded on the surface of graphene-like Co0.85Se nanofilms, and the NH3 · H2O plays an important role in the generation and crystallization of TiO2 nanoparticles. Brunauer-Emmett-Teller measurement shows that the obtained nanocomposites have a larger specific surface area (199.3 m2 g-1) than that of Co0.85Se nanofilms (55.17 m2 g-1) and TiO2 nanoparticles (19.49 m2 g-1). The catalytic tests indicate Co0.85Se-TiO2 nanofilms have the highest activity for 4-NP reduction and hydrazine hydrate decomposition within 10 min and 8 min, respectively, compared with the corresponding precursor Co0.85Se nanofilms and TiO2 nanoparticles. The enhanced catalytic performance can be attributed to the larger specific surface area and higher rate of interfacial charge transfer in the heterojunction than that of the single components. In addition, recycling tests show that the as-synthesized sample presents stable conversion efficiency for 4-NP reduction.

  16. Investigation Of The Hydrolysis Of Isocyanic Acid In Urea SCR: Catalyst Screening And Low-Temperature Kinetics

    Energy Technology Data Exchange (ETDEWEB)

    Piazzesi, G.; Elsener, M.; Kroecher, O.; Wokaun, A.

    2005-03-01

    Several oxide catalysts were tested for the hydrolysis of isocyanic acid under typical diesel exhaust conditions. Among the tested catalysts, TiO{sub 2} and ZrO{sub 2} have been shown to be the most active catalysts. The kinetics of the HNCO hydrolysis over TiO{sub 2} at low temperatures was studied and reaction orders and the activation energy were determined. The effect of NO{sub 2} on the catalytic activity of TiO{sub 2} was also investigated, revealing that, at low temperatures, the formation of ammonium nitrate inhibits the reaction. (author)

  17. 基于钛锡载体的SCR低温脱硝催化剂的表面性质研究%Study on the surface properties of TiO2-SnO2 supported catalysts for low temperature selective catalytic reduction of NOx

    Institute of Scientific and Technical Information of China (English)

    郭婉秋; 张亚平; 王文选; 赵明; 王俊杰; 沈凯; 王龙飞; 杨林军

    2015-01-01

    TiO2-SnO2 mixed oxide was prepared by a co-precipitation method and xCeO2/TiO2-SnO2 catalysts were prepared using the impregnation method. The physicochemical properties were investigated by X-ray diffraction ( XRD) , BET specific surface area measurement, H2 temperature-programmed reduction ( H2-TPR) , NH3 temperature-programmed desorption ( NH3-TPD ) , high-resolution transmission electron microscopy ( HRTEM ) , and in situ diffuse reflectance infrared spectroscopy ( DRIFTS ) . Meanwhile, their catalytic performance for the selective catalytic reduction of NOx with NH3 ( NH3-SCR) was tested. It was found that 0. 1Ce/TiO2-SnO2 had higher NOx conversion and wider temperature range of 250 ~350℃. Excess loading of CeO2 could lead to the decrease of specific surface area, redox ability and adsorption capacity of ammonia as well as the shrink of effective catalytic temperature range. NH3-TPD result showed that the adsorption of NH3 in weak acid and medium acid sites were significantly enhanced by CeO2 , which was related to the decrease of NH3-SCR reaction temperature. In situ DRIFTS indicated that the strength of Lewis acid sites and Brφnsted acid Sites were markedly enhanced for xCeO2/TiO2-SnO2 catalyst. Besides, new Brφnsted acid Sites appeared at 1 657 ~1 666 cm-1 and NH+4 played the dominant role in the SCR reaction.%采用共沉淀法制备TiO2-SnO2固溶体,浸渍法负载CeO2得到一系列xCeO2/TiO2-SnO2负载型催化剂,在模拟NH3选择性催化还原NOx( NH3-SCR)反应条件下考察催化剂低温脱硝活性。通过X射线衍射( XRD)、比表面积测定( BET)、程序升温还原(H2-TPR)、程序升温脱附(NH3-TPD)、高分辨率透射电子显微镜(HRTEM)、原位漫反射傅里叶变换红外光谱(in situ DRIFTS)等表征技术,研究了氧化铈负载后催化剂的微观结构、表面物种的存在状态、表面酸位等表面性质及NH3吸附特性。结果表明,Ce:Ti 物质的量比为0.1时,催化剂催化脱硝反应活性最

  18. PREPARATION OF Au/SULFONATED POLYSTYRENE CATALYSTS FOR LOW-TEMPERATURE CO OXIDATION

    Institute of Scientific and Technical Information of China (English)

    Shi-hua Wu; Xiu-cheng Zheng; Wei-ping Huang; Shou-min Zhang; Wei Wei

    2001-01-01

    Supported Au catalysts for low-temperature CO oxidation were prepared by solvated metal atom impregnation (SMAI) and conventional impregnation (CI). X-ray photoelectron spectroscopy (XPS) investigations indicated that the elemental gold in all the samples was in the metallic state. XRD measurements showed that the mean diameters of Au particles prepared by SMAI were smaller than those prepared by CI with the same gold content. Catalytic tests showed that the SMAI catalyst had higher CO oxidation activity than the CI catalyst with the same compositions. Both SMAI and CI catalysts exhibited high activity in Iow temperature CO oxidation. Full CO conversion was obtained at 323-383K.``

  19. Effect of Rare Earth Elements on Powder Boro-Carbo-Nitriding at Low Temperature

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    The process of the co-cementation layers of low temperature powder multicomponent thermochemical treatment with B-C-N-RE and the structure and properties were studied and compared with those of conventional boro-carbo-nitriding (B-C-N) by X-ray diffractometer, potentiostat and wear machine. The results show that rare earth elements have significant catalytic effect within proper limits. Both wear resistance and corrosion resistance of the B-C-N-RE co-cementation layer are greatly increased in comparison with those of the B-C-N. The function mechanism of rare earth elements is also discussed.

  20. Dynamic modeling of a three-stage low-temperature ethanol reformer for fuel cell application

    Energy Technology Data Exchange (ETDEWEB)

    Garcia, Vanesa M.; Serra, Maria [Institut de Robotica i Informatica Industrial (CSIC-UPC), Llorens i Artigas 4-6, 08028 Barcelona (Spain); Lopez, Eduardo; Llorca, Jordi [Institut de Tecniques Energetiques, Universitat Politecnica de Catalunya, Diagonal 647, ed. ETSEIB, 08028 Barcelona (Spain)

    2009-07-01

    A low-temperature ethanol reformer based on a cobalt catalyst for the production of hydrogen has been designed aiming the feed of a fuel cell for an autonomous low-scale power production unit. The reformer comprises three stages: ethanol dehydrogenation to acetaldehyde and hydrogen over SnO{sub 2} followed by acetaldehyde steam reforming over Co(Fe)/ZnO catalyst and water gas shift reaction. Kinetic data have been obtained under different experimental conditions and a dynamic model has been developed for a tubular reformer loaded with catalytic monoliths for the production of the hydrogen required to feed a 1 kW PEMFC. (author)

  1. Physical properties of dense, low-temperature plasmas

    Science.gov (United States)

    Redmer, Ronald

    1997-04-01

    Plasmas occur in a wide range of the density-temperature plane. The physical quantities can be expressed by Green's functions which are evaluated by means of standard quantum statistical methods. The influences of many-particle effects such as dynamic screening and self-energy, structure factor and local-field corrections, formation and decay of bound states, degeneracy and Pauli exclusion principle are studied. As a basic concept for partially ionized plasmas, a cluster decomposition is performed for the self-energy as well as for the polarization function. The general model of a partially ionized plasma interpolates between low-density, nonmetallic systems such as atomic vapors and high-density, conducting systems such as metals or fully ionized plasmas. The equations of state, including the location of the critical point and the shape of the coexistence curve, are determined for expanded alkali-atom and mercury fluids. The occurrence of a metal-nonmetal transition near the critical point of the liquid-vapor phase transition leads in these materials to characteristic deviations from the behavior of nonconducting fluids such as the inert gases. Therefore, a unified approach is needed to describe the drastic changes of the electronic properties as well as the variation of the physical properties with the density. Similar results are obtained for the hypothetical plasma phase transition in hydrogen plasma. The transport coefficients (electrical and thermal conductivity, thermopower) are studied within linear response theory given here in the formulation of Zubarev which is valid for arbitrary degeneracy and yields the transport coefficients for the limiting cases of nondegenerate, weakly coupled plasmas (Spitzer theory) as well as degenerate, strongly coupled plasmas (Ziman theory). This linear response method is applied to partially ionized systems such as dense, low-temperature plasmas. Here, the conductivity changes from nonmetallic values up to those typical for

  2. [Reaction of NO with metal oxides and urea supported on activated carbons at low temperature].

    Science.gov (United States)

    Cui, Hua-Fei; Li, Cai-Ting; Lu, Pei; Peng, Dun-Liang; Guo, Jing; Chen, Ling

    2010-11-01

    The catalysts were prepared by activated carbon fiber (ACF) loaded different contents of NiO and NiO-CeO2, Urea was loaded on the prepared catalysts as reductant. The experiments of selective catalytic reductions (SCR) of NO were carried out from 30 to 120 degrees C. The experiments of SEM, BET and XRD of the samples were also carried out selectively to study the catalysts properties, respectively. The experimental results showed that the loaded mass fraction of NiO could greatly affect the catalytic activity of the catalysts. 10% NiO catalyst activity and activity stability were both higher than that of the others, and it could yield about 50% removal efficiency of NO at 90 degrees C. With the loaded mass increasing, the catalytic activity was obviously decreased. And furthermore, the catalyst of 5% NiO-5% CeO2/ACF had the best catalytic activities on SCR NO and stability among the prepared NiO-CeO2/ACF catalysts, and its NO removal efficiency was over 55% at 110 degrees C. When the loaded mass increased, the similar phenomenon was observed, which was due to the decreasing of specific surface area of the catalysts. The metal oxides, loaded on ACF, were the catalytic centers in this study. Moreover, 5% CeO2-5% NiO/ACF had the highest catalytic activity than 10% CeO2/ACF and 10% NiO/ ACF. Therefore, there should be synergistic effect between CeO2 and NiO. Finally, the catalytic mechanism of SCR on NO at low temperature was discussed.

  3. 氨基甲酸酯裂解制HDI热力学分析%Thermodynamic analysis of catalytic decomposition of dimethyl-hexane-1,6-dicarbamate to hexamethylene-1,6-diisocyanate

    Institute of Scientific and Technical Information of China (English)

    孙大雷; 黄振荣; 黄宇嘉; 邓剑如; 晁自胜

    2013-01-01

    The catalytic decomposition of dimethyl-hexane-1,6-dicarbamate (HDU) to hexamethylene-1,6-diisocyanate (HDI) was a complex reaction system.The reaction heat,Gibbs free energy change and equilibrium constant of the reactions were calculated by methods of group contribution.The estimated data were compared with the literature and experimental data,and the results showed that they are reliable,which could be used to guide the laboratory research and industrial production.%由六亚甲基二氨基二甲酸甲酯(HDU)裂解合成六亚甲基-1,6-二异氰酸酯(HDI)为一复合反应体系.用基团贡献法计算了该反应体系的反应热、吉布斯自由能变化、化学反应平衡常数.计算数据与文献值及实验结果比较,表明计算结果可靠,对实验室研究及工业化生产都有重要的指导意义.

  4. Characteristics of La-modified Ni-Al2O3 and Ni-SiO2 catalysts for COx-free hydrogen production by catalytic decomposition of methane

    Institute of Scientific and Technical Information of China (English)

    Chatla; Anjaneyulu; Velisoju; Vijay; Kumar; Suresh; K.Bhargava; Akula; Venugopal

    2013-01-01

    Hydrotalcite precursors of La modified Ni-Al2O3 and Ni-SiO2 catalysts prepared by co-precipitation method and the catalytic activities were examined for the production of COx-free H2 by CH4 decomposition. Physico-chemical characteristics of fresh, reduced and used catalysts were evaluated by XRD, TPR and O2 pulse chemisorptions, TEM and BET-SA techniques. XRD studies showed phases due to hydrotalcite-like precursors in oven dried form produced dispersed NiO species upon calcination in static air above 450 C. Raman spectra of deactivated samples revealed the presence of both ordered and disordered forms of carbon. Ni-La-Al2O3catalyst with a mole ratio of Ni : La : Al = 2 : 0.1 : 0.9 exhibited tremendously high longevity with a hydrogen production rate of 1300 molH2 mol 1 Ni. A direct relationship between Ni metal surface area and hydrogen yields was established.

  5. Low temperature safety of lithium-thionyl chloride cells

    Science.gov (United States)

    Subbarao, S.; Deligiannis, F.; Shen, D. H.; Dawson, S.; Halpert, G.

    The use of lithium thionyl chloride cells for low-temperature applications is presently restricted because of their unsafe behavior. An attempt is made in the present investigation to identify the safe/unsafe low temperature operating conditions and to understand the low temperature cell chemistry responsible for the unsafe behavior. Cells subjected to extended reversal at low rate and -40 C were found to explode upon warm-up. Lithium was found to deposit on the carbon cathodes during reversal. Warming up to room temperature may be accelerating the lithium corrosion in the electrolyte. This may be one of the reasons for the cell thermal runaway.

  6. Low-temperature softening in body-centered cubic alloys

    Science.gov (United States)

    Pink, E.; Arsenault, R. J.

    1979-01-01

    In the low-temperature range, bcc alloys exhibit a lower stress-temperature dependence than the pure base metals. This effect often leads to a phenomenon that is called 'alloy softening': at low temperatures, the yield stress of an alloy may be lower than that of the base metal. Various theories are reviewed; the most promising are based either on extrinsic or intrinsic models of low-temperature deformation. Some other aspects of alloy softening are discussed, among them the effects on the ductile-brittle transition temperature.

  7. Synthesis of a chabazite-supported copper catalyst with full mesopores for selective catalytic reduction of nitrogen oxides at low temperature%具有丰富介孔Cu-SAPO-34催化剂制备及其低温氨气选择性催化还原反应

    Institute of Scientific and Technical Information of China (English)

    刘计省; 刘坚; 赵震; 宋卫余; 韦岳长; 段爱军; 姜桂元

    2016-01-01

    催化剂的物理化学性质。  XRD 测试结果证实, H-Cu-SAPO-34催化剂具有典型的 CHA 结构。 TEM 和 N2吸附-脱附测试结果表明, H-Cu-SAPO-34催化剂具有丰富的介孔结构。 Al-NMR测试结果表明,多种配位的Al物种存在于H-Cu-SAPO-34中。 UV-Vis DRS 测试结果证实了孤立 Cu2+和高分散的 CuO 的存在,没有观察到(Cu-O-Cu)2+和 CuAl2O4物种的存在。 ICP-AES和XPS测试结果表明, H-Cu-SAPO-34催化剂具有相似的Cu含量,并且H-Cu-SAPO-34-20催化剂具有最高的Cu2+含量。 H2-TPR测试结果表明, H-Cu-SAPO-34-20催化剂具有最低的孤立Cu2+还原温度以及最高的孤立Cu2+含量。这可能有利于其NH3-SCR活性提高。同时H2-TPR还表明, H-Cu-SAPO-34催化剂中存在含量不等的孤立Cu+,并且孤立Cu2+是NH3-SCR反应的主要活性中心。 EPR测试结果进一步表明,位于SAPO-34椭球腔内(Site (I))的孤立Cu2+是该反应的主要活性位。  由NO的NH3-SCR反应测试结果来看,相比于普通的Cu/SAPO-34催化剂,具有丰富介孔结构的H-Cu-SAPO-34催化剂呈现出更高的低温催化活性,同时H-Cu-SAPO-34-20催化剂具有最高的低温NH3-SCR催化活性,这与其较高的活性Cu2+含量以及较低的孤立Cu2+还原温度密切相关。动力学测试结果表明,所合成的H-Cu-SAPO-34多级孔催化剂具有相似的活化能(Ea =98 kJ/mol),并且该值远大于普通CHA基SCR催化剂,这意味着介孔的存在确实大大降低了反应物分子在H-Cu-SAPO-34孔道内的扩散阻力,提高了反应物分子与活性位的接触概率,从而提高了其低温NH3-SCR催化性能。%A series of meso‐microporous copper‐supporting chabazite molecular sieve (Cu‐SAPO‐34) catalysts with excellent performance in low‐temperature ammonia selective catalytic reduction (NH3‐SCR) have been synthesized via a one‐pot hydrothermal crystallization method. The physicochemical properties of the

  8. Micromachined Active Magnetic Regenerator for Low Temperature Magnetic Coolers Project

    Data.gov (United States)

    National Aeronautics and Space Administration — NASA's future science missions to investigate the structure and evolution of the universe require highly efficient, very low temperature coolers for low noise...

  9. Total Dose Effects on Bipolar Integrated Circuits at Low Temperature

    Science.gov (United States)

    Johnston, A. H.; Swimm, R. T.; Thorbourn, D. O.

    2012-01-01

    Total dose damage in bipolar integrated circuits is investigated at low temperature, along with the temperature dependence of the electrical parameters of internal transistors. Bandgap narrowing causes the gain of npn transistors to decrease far more at low temperature compared to pnp transistors, due to the large difference in emitter doping concentration. When irradiations are done at temperatures of -140 deg C, no damage occurs until devices are warmed to temperatures above -50 deg C. After warm-up, subsequent cooling shows that damage is then present at low temperature. This can be explained by the very strong temperature dependence of dispersive transport in the continuous-time-random-walk model for hole transport. For linear integrated circuits, low temperature operation is affected by the strong temperature dependence of npn transistors along with the higher sensitivity of lateral and substrate pnp transistors to radiation damage.

  10. 2014 Low-Temperature and Coproduced Geothermal Resources Fact Sheet

    Energy Technology Data Exchange (ETDEWEB)

    Tim Reinhardt, Program Manager

    2014-09-01

    As a growing sector of geothermal energy development, the Low-Temperature Program supports innovative technologies that enable electricity production and cascaded uses from geothermal resources below 300° Fahrenheit.

  11. Highly Effective Thermal Regenerator for Low Temperature Cryocoolers Project

    Data.gov (United States)

    National Aeronautics and Space Administration — Future missions to investigate the structure and evolution of the universe require highly efficient, low-temperature cryocoolers for low-noise detector systems. We...

  12. Lightweight Superconducting Magnets for Low Temperature Magnetic Coolers Project

    Data.gov (United States)

    National Aeronautics and Space Administration — NASA's future science missions to investigate the structure and evolution of the universe require efficient, very low temperature coolers for low noise detector...

  13. Low-temperature intracrystalline deformation microstructures in quartz

    NARCIS (Netherlands)

    Derez, Tine; Pennock, Gill; Drury, Martyn; Sintubin, Manuel

    A review of numerous genetic interpretations of the individual low-temperature intracrystalline deformation microstructures in quartz shows that there is no consensus concerning their formation mechanisms. Therefore, we introduce a new, purely descriptive terminology for the three categories of

  14. Micromachined Active Magnetic Regenerator for Low Temperature Magnetic Coolers Project

    Data.gov (United States)

    National Aeronautics and Space Administration — NASA's future science missions to investigate the structure and evolution of the universe require highly efficient, very low temperature coolers for low noise...

  15. 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)

  16. Preliminary low temperature tests of a digital signal processor

    Science.gov (United States)

    Zebulum, Ricardo S.; Ramesham, Rajeshuni; Stoica, Adrian; Keymeulen, Didier; Daud, Taher; Sekanina, Lukas

    2005-01-01

    This paper describes an initial experiment performed to assess the electrical behavior of the Innovative Integration board containing a Digital Signal Processor (DSP) with its JTAG (Blackhawk) connector at low temperatures. The objective of the experiment is to determine the lowest temperature at which the DSP can operate. The DSP was tested at various low-temperatures and a Genetic Algorithm was used as the DSP test program.

  17. Oxidation Degradation of Aqueous Carbofuran Induced by Low Temperature Plasma

    Science.gov (United States)

    Pu, Lumei; Gao, Jinzhang; Hu, Yusen; Liang, Huiguang; Xiao, Wen; Wang, Xingmin

    2008-06-01

    The oxidative degradation of aqueous carbofuran, a heavily used toxic carbamate insecticide by low temperature plasma, was investigated. The results show that the treatment efficiency increases with the increase in initial concentration. Raising the treatment temperature and changing the pH value can result in enhanced degradation of carbofuran in solution. The results also show that low temperature plasma treatment can effectively remove chemical oxygen demand (COD) of carbofuran in the solution.

  18. Oxidation Degradation of Aqueous Carbofuran Induced by Low Temperature Plasma

    Institute of Scientific and Technical Information of China (English)

    PU Lumei; GAO Jinzhang; HU Yusen; LIANG Huiguang; XIAO Wen; WANG Xingmin

    2008-01-01

    The oxidative degradation of aqueous carbofuran, a heavily used toxic carbamate insecticide by low temperature plasma, was investigated. The results show that the treatment efficiency increases with the increase in initial concentration. Raising the treatment temperature and changing the pH value can result in enhanced degradation of carbofuran in solution. The results also show that low temperature plasma treatment can effectively remove chemical oxygen demand (COD) of carbofuran in the solution.

  19. Low temperature magnetic structure of MnSe

    Indian Academy of Sciences (India)

    J B C Efrem D'sa; P A Bhobe; K R Priolkar; A Das; P S R Krishna; P R Sarode; R B Prabhu

    2004-08-01

    In this paper we report low temperature neutron diffraction studies on MnSe in order to understand the anomalous behaviour of their magnetic and transport properties. Our study indicates that at low temperatures MnSe has two coexisting crystal structures, high temperature NaCl and hexagonal NiAs. NiAs phase appears below 266 K and is antiferromagnetically ordered at all temperatures while the NaCl phase orders antiferromagnetically at 130 K.

  20. Measured Performance of a Low Temperature Air Source Heat Pump

    Energy Technology Data Exchange (ETDEWEB)

    R.K. Johnson

    2013-09-01

    A 4-ton Low Temperature Heat Pump (LTHP) manufactured by Hallowell International was installed in a residence near New Haven, Connecticut and monitored over two winters of operation. After attending to some significant service issues, the heat pump operated as designed. This report should be considered a review of the dual compressor “boosted heat pump” technology. The Low Temperature Heat Pump system operates with four increasing levels of capacity (heat output) as the outdoor temperature drops.

  1. Low temperature Hall effect in bismuth chalcogenides thin films

    OpenAIRE

    Kuntsevich, A. Yu.; Gabdullin, A. A.; Prudkogliad, V. A.; Selivanov, Yu. G.; Chizhevskii, E. G.; Pudalov, V. M.

    2016-01-01

    Bismuth chalcogenides are the most studied 3D topological insulators. As a rule, at low temperatures thin films of these materials demonstrate positive magnetoresistance due to weak antilocalization. Weak antilocalization should lead to resistivity decrease at low temperatures; in experiments, however, resistivity grows as temperature decreases. From transport measurements for several thin films (with various carrier density, thickness, and carrier mobility), and by using purely phenomenologi...

  2. Correlation functions of one-dimensional bosons at low temperature

    Energy Technology Data Exchange (ETDEWEB)

    Kozlowski, K.K. [Deutsches Elektronen-Synchrotron (DESY), Hamburg (Germany); Maillet, J.M. [CNRS, ENS Lyon (France). Lab. de Physique; Slavnov, N.A. [Steklov Mathematical Institute, Moscow (Russian Federation)

    2010-12-15

    We consider the low-temperature limit of the long-distance asymptotic behavior of the finite temperature density-density correlation function in the one-dimensional Bose gas derived recently in the algebraic Bethe Ansatz framework. Our results confirm the predictions based on the Luttinger liquid and conformal field theory approaches. We also demonstrate that the amplitudes arising in this asymptotic expansion at low-temperature coincide with the amplitudes associated with the so-called critical form factors. (orig.)

  3. Biological and Biomimetic Low-Temperature Routes to Materials for Energy Applications

    Energy Technology Data Exchange (ETDEWEB)

    Morse, Daniel E. [Univ. of California, Santa Barbara, CA (United States). Inst. for Collaborative Biotechnologies

    2016-08-29

    New materials are needed to significantly improve the efficiencies of energy harnessing, transduction and storage, yet the synthesis of advanced composites and multi-metallic semiconductors with nanostructures optimized for these functions remains poorly understood and even less well controlled. To help address this need, we proposed three goals: (1) to further investigate the hierarchical structure of the biologically synthesized silica comprising the skeletal spicules of sponges that we discovered, to better resolve the role and mechanism of templating by the hierarchically assembled silicatein protein filament; (2) to extend our molecular and genetic analyses and engineering of silicatein, the self-assembling, structure-directing, silica-synthesizing enzyme we discovered and characterized, to better understand and manipulate the catalysis and templating of semiconductor synthesis,; and (3) to further investigate, scale up and harness the biologically inspired, low-temperature, kinetically controlled catalytic synthesis method we developed (based on the mechanism we discovered in silicatein) to investigate the kinetic control of the structure-function relationships in magnetic materials, and develop new materials for energy applications. The bio-inspired catalytic synthesis method we have developed is low-cost, low temperature, and operates without the use of polluting chemicals. In addition to direct applications for improvement of batteries and fuel cells, the broader impact of this research includes a deeper fundamental understanding of the factors governing kinetically controlled synthesis and its control of the emergent nanostructure and performance of a wide range of nanomaterials for energy applications.

  4. DRIFT study of CuO-CeO₂-TiO₂ mixed oxides for NOx reduction with NH₃ at low temperatures.

    Science.gov (United States)

    Chen, Lei; Si, Zhichun; Wu, Xiaodong; Weng, Duan

    2014-06-11

    A CuO-CeO2-TiO2 catalyst for selective catalytic reduction of NOx with NH3 (NH3-SCR) at low temperatures was prepared by a sol-gel method and characterized by X-ray diffraction, Brunner-Emmett-Teller surface area, ultraviolet-visible spectroscopy, H2 temperature-programmed reduction, scanning electron microscopy and in situ diffuse reflectance infrared Fourier transform spectroscopy (in situ DRIFTS). The CuO-CeO2-TiO2 ternary oxide catalyst shows excellent NH3-SCR activity in a low-temperature range of 150-250 °C. Lewis acid sites generated from Cu(2+) are the main active sites for ammonia activation at low temperature, which is crucial for low temperature NH3-SCR activity. The introduction of ceria results in increased reducibility of CuO species and strong interactions between CuO particles with the matrix. The interactions between copper, cerium and titanium oxides lead to high dispersion of metal oxides with increased active oxygen and enhanced catalyst acidity. Homogeneously mixed metal oxides facilitate the "fast SCR" reaction among Cu(2+)-NO, nitrate (coordinated on cerium sites) and ammonia (on titanium sites) on the CuO-CeO2-TiO2 catalyst at low temperatures.

  5. Ozone Decomposition on the Surface of Metal Oxide Catalyst

    Directory of Open Access Journals (Sweden)

    Batakliev Todor Todorov

    2014-12-01

    Full Text Available The catalytic decomposition of ozone to molecular oxygen over catalytic mixture containing manganese, copper and nickel oxides was investigated in the present work. The catalytic activity was evaluated on the basis of the decomposition coefficient which is proportional to ozone decomposition rate, and it has been already used in other studies for catalytic activity estimation. The reaction was studied in the presence of thermally modified catalytic samples operating at different temperatures and ozone flow rates. The catalyst changes were followed by kinetic methods, surface measurements, temperature programmed reduction and IR-spectroscopy. The phase composition of the metal oxide catalyst was determined by X-ray diffraction. The catalyst mixture has shown high activity in ozone decomposition at wet and dry O3/O2 gas mixtures. The mechanism of catalytic ozone degradation was suggested.

  6. Metathesis in the generation of low-temperature gas in marine shales.

    Science.gov (United States)

    Mango, Frank D; Jarvie, Daniel M

    2010-01-20

    The recent report of low-temperature catalytic gas from marine shales took on additional significance with the subsequent disclosure of natural gas and low-temperature gas at or near thermodynamic equilibrium in methane, ethane, and propane. It is important because thermal cracking, the presumed source of natural gas, cannot generate these hydrocarbons at equilibrium nor can it bring them to equilibrium over geologic time. The source of equilibrium and the source of natural gas are either the same (generation under equilibrium control) or closely associated. Here we report the catalytic interconversion of hydrocarbons (metathesis) as the source of equilibrium in experiments with Cretaceous Mowry shale at 100 degrees C. Focus was on two metathetic equilibria: methane, ethane, and propane, reported earlier, Q (K = [(C(1))*(C(3))]/[(C(2))(2)]), and between these hydrocarbons and n-butane, Q* (K = [(C(1))*(n-C(4))]/[(C(2))*(C(3))]), reported here for the first time. Two observations stand out. Initial hydrocarbon products are near equilibrium and have maximum average molecular weights (AMW). Over time, products fall from equilibrium and AMW in concert. It is consistent with metathesis splitting olefin intermediates [C(n)] to smaller intermediates (fission) as gas generation creates open catalytic sites ([ ]): [C(n)] + [ ] --> [C(n-m)] + [C(m)]. Fission rates increasing exponentially with olefin molecular weight could contribute to these effects. AMW would fall over time, and selective fission of [C(3)] and [n-C(4)] would draw Q and Q* from equilibrium. The results support metathesis as the source of thermodynamic equilibrium in natural gas.

  7. Metathesis in the generation of low-temperature gas in marine shales

    Directory of Open Access Journals (Sweden)

    Jarvie Daniel M

    2010-01-01

    Full Text Available Abstract The recent report of low-temperature catalytic gas from marine shales took on additional significance with the subsequent disclosure of natural gas and low-temperature gas at or near thermodynamic equilibrium in methane, ethane, and propane. It is important because thermal cracking, the presumed source of natural gas, cannot generate these hydrocarbons at equilibrium nor can it bring them to equilibrium over geologic time. The source of equilibrium and the source of natural gas are either the same (generation under equilibrium control or closely associated. Here we report the catalytic interconversion of hydrocarbons (metathesis as the source of equilibrium in experiments with Cretaceous Mowry shale at 100°C. Focus was on two metathetic equilibria: methane, ethane, and propane, reported earlier, Q (K = [(C1*(C3]/[(C22], and between these hydrocarbons and n-butane, Q* (K = [(C1*(n-C4]/[(C2*(C3], reported here for the first time. Two observations stand out. Initial hydrocarbon products are near equilibrium and have maximum average molecular weights (AMW. Over time, products fall from equilibrium and AMW in concert. It is consistent with metathesis splitting olefin intermediates [Cn] to smaller intermediates (fission as gas generation creates open catalytic sites ([ ]: [Cn] + [ ] → [Cn-m] + [Cm]. Fission rates increasing exponentially with olefin molecular weight could contribute to these effects. AMW would fall over time, and selective fission of [C3] and [n-C4] would draw Q and Q* from equilibrium. The results support metathesis as the source of thermodynamic equilibrium in natural gas.

  8. Research Status Quo and Future of Low Temperature Wheat Genotypes

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    Low temperature wheat genotypes are a group of wheat with a slightly low canopy (plant) temperature, and the research on their biological characters and utilization in wheat breeding has been done at home and abroad for more than 20 years, and has made great progress. The research contents and advances include the following respects: Wheat genotypes with slightly low canopy temperature have been verified to exist in nature; these wheat genotypes, which present cold temperature, are superior to conventional wheat materials in some important biological characters and particularly prominently in metabolic function and cellular structure; when they suffer stresses such as drought, high temperature and overcast and rainy weather, they still retain their superiority in some of their important biological characters and therefore have a wide range of ecological adaptability; slightly low canopy temperatures of these genotypes are closely correlated with low temperatures of their second heat sources and their vigorous plants; since their low canopy temperatures can be inherited, they can exert favorable influence on the temperatures of their offspring while crossing with other wheat materials, and in particular, the discovery of cold-source wheat as a contributor to low temperature, has further formed good conditions for breeding high and stable quality low temperature wheat varieties with a high and stable yield. Thus, low temperature wheat genotypes are of great research importance and have great prospects.

  9. Energy and exergy analysis of low temperature district heating network

    DEFF Research Database (Denmark)

    Li, Hongwei; Svendsen, Svend

    2012-01-01

    Low temperature district heating with reduced network supply and return temperature provides better match of the low quality building heating demand and the low quality heating supply from waste heat or renewable energy. In this paper, a hypothetical low temperature district heating network...... is designed to supply heating for 30 low energy detached residential houses. The network operational supply/return temperature is set as 55 °C/25 °C, which is in line with a pilot project carried out in Denmark. Two types of in-house substations are analyzed to supply the consumer domestic hot water demand....... The space heating demand is supplied through floor heating in the bathroom and low temperature radiators in the rest of rooms. The network thermal and hydraulic conditions are simulated under steady state. A district heating network design and simulation code is developed to incorporate the network...

  10. The Electromagnetic Mass Difference of Pions at Low Temperature

    CERN Document Server

    Manuel, C

    1999-01-01

    We compute low temperature corrections to the electromagnetic mass difference of pions in the chiral limit. The computation is done in a model independent way in the framework of chiral perturbation theory, using the background field method and the hard thermal loop approximation. We also generalize at low temperature the sum rule of Das et al. We find that the mass difference between the charged and neutral pions decreases at low temperature $T$ with respect to the T=0 value. This is so in spite of the fact that charged particles always get a thermal correction to their masses of order $\\sim eT$, where $e$ is the gauge coupling constant. Our result can be understood as a consequence of the tendency towards chiral symmetry restoration at finite temperature.

  11. Low Temperature Shape Memory Alloys for Adaptive, Autonomous Systems Project

    Science.gov (United States)

    Falker, John; Zeitlin, Nancy; Williams, Martha; Benafan, Othmane; Fesmire, James

    2015-01-01

    The objective of this joint activity between Kennedy Space Center (KSC) and Glenn Research Center (GRC) is to develop and evaluate the applicability of 2-way SMAs in proof-of-concept, low-temperature adaptive autonomous systems. As part of this low technology readiness (TRL) activity, we will develop and train low-temperature novel, 2-way shape memory alloys (SMAs) with actuation temperatures ranging from 0 C to 150 C. These experimental alloys will also be preliminary tested to evaluate their performance parameters and transformation (actuation) temperatures in low- temperature or cryogenic adaptive proof-of-concept systems. The challenge will be in the development, design, and training of the alloys for 2-way actuation at those temperatures.

  12. Low-temperature random matrix theory at the soft edge

    Science.gov (United States)

    Edelman, Alan; Persson, Per-Olof; Sutton, Brian D.

    2014-06-01

    "Low temperature" random matrix theory is the study of random eigenvalues as energy is removed. In standard notation, β is identified with inverse temperature, and low temperatures are achieved through the limit β → ∞. In this paper, we derive statistics for low-temperature random matrices at the "soft edge," which describes the extreme eigenvalues for many random matrix distributions. Specifically, new asymptotics are found for the expected value and standard deviation of the general-β Tracy-Widom distribution. The new techniques utilize beta ensembles, stochastic differential operators, and Riccati diffusions. The asymptotics fit known high-temperature statistics curiously well and contribute to the larger program of general-β random matrix theory.

  13. Low-temperature electron microscopy: techniques and protocols.

    Science.gov (United States)

    Fleck, Roland A

    2015-01-01

    Low-temperature electron microscopy endeavors to provide "solidification of a biological specimen by cooling with the aim of minimal displacement of its components through the use of low temperature as a physical fixation strategy" (Steinbrecht and Zierold, Cryotechniques in biological electron microscopy. Springer-Verlag, Berlin, p 293, 1987). The intention is to maintain confidence that the tissue observed retains the morphology and dimensions of the living material while also ensuring soluble cellular components are not displaced. As applied to both scanning and transmission electron microscopy, cryo-electron microscopy is a strategy whereby the application of low-temperature techniques are used to reduce or remove processing artifacts which are commonly encountered in more conventional room temperature electron microscopy techniques which rely heavily on chemical fixation and heavy metal staining. Often, cryo-electron microscopy allows direct observation of specimens, which have not been stained or chemically fixed.

  14. Low-temperature, selective catalytic deoxygenation of vegetable oil in supercritical fluid media.

    Science.gov (United States)

    Kim, Seok Ki; Lee, Hong-Shik; Hong, Moon Hyun; Lim, Jong Sung; Kim, Jaehoon

    2014-02-01

    The effects of supercritical fluids on the production of renewable diesel-range hydrocarbons from natural triglycerides were investigated. Various supercritical fluids, which included CO2 (scCO2 ), propane (scC3 H8 ) and n-hexane (scC6 H14 ), were introduced with H2 and soybean oil into a fixed-bed reactor that contained pre-activated CoMo/γ-Al2 O3 . Among these supercritical fluids, scC3 H8 and scC6 H14 efficiently allowed the reduction of the reaction temperature by as much as 50 °C as a result of facilitated heat and mass transfer and afforded similar yields to reactions in the absence of supercritical fluids. The compositional analyses of the gas and liquid products indicated that the addition of scC3 H8 during the hydrotreatment of soybean oil promoted specific deoxygenation pathways, decarbonylation and decarboxylation, which consumed less H2 than the hydrodeoxygenation pathway. As a result, the quantity of H2 required to obtain a high yield of diesel-range hydrocarbons could be reduced to 57 % if scC3 H8 was used. As decarboxylation and decarbonylation are mildly endothermic reactions, the reduced heat transfer resistance in scC3 H8 may drive the deoxygenation reaction to thermodynamically favourable pathways.

  15. Electro-catalytically Active, High Surface Area Cathodes for Low Temperature SOFCs

    Energy Technology Data Exchange (ETDEWEB)

    Eric D. Wachsman

    2006-09-30

    This research focused on developing low polarization (area specific resistance, ASR) cathodes for intermediate temperature solid oxide fuel cells (IT-SOFCs). In order to accomplish this we focused on two aspects of cathode development: (1) development of novel materials; and (2) developing the relationships between microstructure and electrochemical performance. The materials investigated ranged from Ag-bismuth oxide composites (which had the lowest reported ASR at the beginning of this contract) to a series of pyrochlore structured ruthenates (Bi{sub 2-x}M{sub x}Ru{sub 2}O{sub 7}, where M = Sr, Ca, Ag; Pb{sub 2}Ru{sub 2}O{sub 6.5}; and Y{sub 2-2x}Pr{sub 2x}Ru{sub 2}O{sub 7}), to composites of the pyrochlore ruthenates with bismuth oxide. To understand the role of microstructure on electrochemical performance, we optimized the Ag-bismuth oxide and the ruthenate-bismuth oxide composites in terms of both two-phase composition and particle size/microstructure. We further investigated the role of thickness and current collector on ASR. Finally, we investigated issues of stability and found the materials investigated did not form deleterious phases at the cathode/electrolyte interface. Further, we established the ability through particle size modification to limit microstructural decay, thus, enhancing stability. The resulting Ag-Bi{sub 0.8}Er{sub 0.2}O{sub 1.5} and Bi{sub 2}Ru{sub 2}O{sub 7{sup -}}Bi{sub 0.8}Er{sub 0.2}O{sub 1.5} composite cathodes had ASRs of 1.0 {Omega} cm{sup 2} and 0.73 {Omega}cm{sup 2} at 500 C and 0.048 {Omega}cm{sup 2} and 0.053 {Omega}cm{sup 2} at 650 C, respectively. These ASRs are truly impressive and makes them among the lowest IT-SOFC ASRs reported to date.

  16. Exergy Transfer Characteristics on Low Temperature Heat Exchangers

    Science.gov (United States)

    Wu, S. Y.; Yuan, X. F.; Li, Y. R.; Peng, L.

    By analyzing exergy transfer process of the low temperature heat exchangers operating below the surrounding temperature, the concept of exergy transfer coefficient is put forward and the expressions which involving relevant variables for the exergy transfer coefficient, the heat transfer units number and the ratio of cold to hot fluids heat capacity rate, etc. are derived. Taking the parallel flow, counter flow and cross flow low temperature heat exchangers as examples, the numerical results of exergy transfer coefficient are given and the comparison of exergy transfer coefficient with heat transfer coefficient is analyzed.

  17. Infrared Behavior of Dipolar Bose Systems at Low Temperatures

    Science.gov (United States)

    Pastukhov, Volodymyr

    2017-01-01

    We rigorously discuss the infrared behavior of the uniform three-dimensional dipolar Bose systems. In particular, it is shown that low-temperature physics of the system is controlled by two parameters, namely isothermal compressibility and intensity of the dipole-dipole interaction. By using a hydrodynamic approach, we calculate the spectrum and damping of low-lying excitations and analyze the infrared behavior of the one-particle Green's function. The low-temperature corrections to the anisotropic superfluid density as well as condensate depletion are found. Additionally, we derive equations of the two-fluid hydrodynamics for dipolar Bose systems and calculate velocities of first and second sound.

  18. Instrument for Measuring Thermal Conductivity of Materials at Low Temperatures

    Science.gov (United States)

    Fesmire, James; Sass, Jared; Johnson, Wesley

    2010-01-01

    With the advance of polymer and other non-metallic material sciences, whole new series of polymeric materials and composites are being created. These materials are being optimized for many different applications including cryogenic and low-temperature industrial processes. Engineers need these data to perform detailed system designs and enable new design possibilities for improved control, reliability, and efficiency in specific applications. One main area of interest is cryogenic structural elements and fluid handling components and other parts, films, and coatings for low-temperature application. An important thermal property of these new materials is the apparent thermal conductivity (k-value).

  19. Exergy and Energy Analysis of Low Temperature District Heating Network

    DEFF Research Database (Denmark)

    Li, Hongwei; Svendsen, Svend

    Low temperature district heating (LTDH) with reduced network supply and return temperature provides better match of the low quality building thermal demand and the low quality waste heat supply. In this paper, an exemplary LTDH network was designed for 30 low energy demand residential houses, which...... is in line with a pilot project that is carrying out in Denmark with network supply/return temperature at 55oC/25 oC. The consumer domestic hot water (DHW) demand is supplied with a special designed district heating (DH) storage tank. The space heating (SH) demand is supplied with a low temperature radiator...

  20. Pre-incubation and low temperatures in quantitative radioreceptor assays

    Energy Technology Data Exchange (ETDEWEB)

    Ensing, K.; de Zeeuw, R.A.

    1984-01-01

    The detection limits of drugs in quantitative RRA are primarily determined by their affinities towards the receptor. Yet, the concentration of radiolabeled ligand, necessary for quantification of receptor-bound drug, increases the theoretical detection limit. Therefore the influences of low temperatures and pre-incubation on the detection limit was studied. Analysis of experimental data suggests that when a well-defined incubation procedure is used, pre-incubation and low temperatures will increase sensitivity without loss of accuracy and precision. 6 references, 2 figures.

  1. Efficient low-temperature thermophotovoltaic emitters from metallic photonic crystals.

    Science.gov (United States)

    Nagpal, Prashant; Han, Sang Eon; Stein, Andreas; Norris, David J

    2008-10-01

    We examine the use of metallic photonic crystals as thermophotovoltaic emitters. We coat silica woodpile structures, created using direct laser writing, with tungsten or molybdenum. Optical reflectivity and thermal emission measurements near 650 degrees C demonstrate that the resulting structures should provide efficient emitters at relatively low temperatures. When matched to InGaAsSb photocells, our structures should generate over ten times more power than solid emitters while having an optical-to-electrical conversion efficiency above 32%. At such low temperatures, these emitters have promise not only in solar energy but also in harnessing geothermal and industrial waste heat.

  2. Space as a low-temperature regime of graphs

    CERN Document Server

    Conrady, Florian

    2010-01-01

    I define a statistical model of graphs in which 2-dimensional spaces arise at low temperature. The configurations are given by graphs with a fixed number of edges and the Hamiltonian is a simple, local function of the graphs. Simulations show that there is a transition between a low-temperature regime in which the graphs form triangulations of 2-dimensional surfaces and a high-temperature regime, where the surfaces disappear. I use data for the specific heat and other observables to discuss whether this is a phase transition. The surface states are analyzed with regard to topology and defects.

  3. Heat Transfer and Cooling Techniques at Low Temperature

    CERN Document Server

    Baudouy, B

    2014-07-17

    The first part of this chapter gives an introduction to heat transfer and cooling techniques at low temperature. We review the fundamental laws of heat transfer (conduction, convection and radiation) and give useful data specific to cryogenic conditions (thermal contact resistance, total emissivity of materials and heat transfer correlation in forced or boiling flow for example) used in the design of cooling systems. In the second part, we review the main cooling techniques at low temperature, with or without cryogen, from the simplest ones (bath cooling) to the ones involving the use of cryocoolers without forgetting the cooling flow techniques.

  4. Final Report: Wetted Cathodes for Low-Temperature Aluminum Smelting

    Energy Technology Data Exchange (ETDEWEB)

    Brown, Craig W

    2002-09-30

    A low-temperature aluminum smelting process being developed differs from the Hall-Heroult process in several significant ways. The low-temperature process employs a more acidic electrolyte than cryolite, an alumina slurry, oxygen-generating metal anodes, and vertically suspended electrodes. Wetted and drained vertical cathodes are crucial to the new process. Such cathodes represent a significant portion of the capital costs projected for the new technology. Although studies exist of wetted cathode technology with Hall-Heoult cells, the differences make such a study desirable with the new process.

  5. Low temperature diffusivity of self-interstitial defects in tungsten

    Science.gov (United States)

    Swinburne, Thomas D.; Ma, Pui-Wai; Dudarev, Sergei L.

    2017-07-01

    The low temperature diffusivity of nanoscale crystal defects, where quantum mechanical fluctuations are known to play a crucial role, are essential to interpret observations of irradiated microstructures conducted at cryogenic temperatures. Using density functional theory calculations, quantum heat bath molecular dynamics and open quantum systems theory, we evaluate the low temperature diffusivity of self-interstitial atom clusters in tungsten valid down to temperatures of 1 K. Due to an exceptionally low defect migration barrier, our results show that interstitial defects exhibit very high diffusivity of order {10}3 μ {{{m}}}2 {{{s}}}-1 over the entire range of temperatures investigated.

  6. Gold on Different Manganese Oxides : Ultra-Low-Temperature CO Oxidation over Colloidal Gold Supported on Bulk-MnO2 Nanomaterials

    NARCIS (Netherlands)

    Gu, Dong; Tseng, Jo-Chi; Weidenthaler, Claudia; Bongard, Hans-Josef; Spliethoff, Bernd; Schmidt, Wolfgang; Soulimani, Fouad; Weckhuysen, Bert M; Schüth, Ferdi

    2016-01-01

    Nanoscopic gold particles have gained very high interest because of their promising catalytic activity for various chemicals reactions. Among these reactions, low-temperature CO oxidation is the most extensively studied one due to its practical relevance in environmental applications and the fundame

  7. Effect of nitrogen-containing impurities on the activity of perovskitic catalysts for the catalytic combustion of methane.

    Science.gov (United States)

    Buchneva, Olga; Gallo, Alessandro; Rossetti, Ilenia

    2012-11-05

    LaMnO(3), either pure or doped with 10 mol % Sr, has been prepared by flame pyrolysis in nanostructured form. Such catalysts have been tested for the catalytic flameless combustion of methane, achieving very high catalytic activity. The resistance toward poisoning by some model N-containing impurities has been checked in order to assess the possibility of operating the flameless catalytic combustion with biogas, possibly contaminated by S- or N-based compounds. This would be a significant improvement from the environmental point of view because the application of catalytic combustion to gas turbines would couple improved energy conversion efficiency and negligible noxious emissions, while the use of biogas would open the way to energy production from a renewable source by means of very efficient technologies. A different behavior has been observed for the two catalysts; namely, the undoped sample was more or less heavily poisoned, whereas the Sr-doped sample showed slightly increasing activity upon dosage of N-containing compounds. A possible reaction mechanism has been suggested, based on the initial oxidation of the organic backbone, with the formation of NO. The latter may adsorb more or less strongly depending on the availability of surface oxygen vacancies (i.e., depending on doping). Decomposition of NO may leave additional activated oxygen species on the surface, available for low-temperature methane oxidation and so improving the catalytic performance.

  8. Unsteady catalytic processes and sorption-catalytic technologies

    Energy Technology Data Exchange (ETDEWEB)

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

    2007-07-31

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

  9. Low Temperature PureB Technology for CMOS Compatible Photodetectors

    NARCIS (Netherlands)

    Mohammadi, V.

    2015-01-01

    In this thesis, conventional high temperature (HT, 700 °C) PureB technology is optimized in order to fabricate detectors with improved key parameters such as the spatial uniformity of the responsivity. A novel technology for low temperature (LT, 400 °C) boron deposition is developed providing a unif

  10. Low-temperature phase transformation of CZTS thin films

    Science.gov (United States)

    Zhao, Wei; Du, Lin-Yuan; Liu, Lin-Lin; Sun, Ya-Li; Liu, Zhi-Wei; Teng, Xiao-Yun; Xie, Juan; Liu, Kuang; Yu, Wei; Fu, Guang-Sheng; Gao, Chao

    2017-04-01

    The low temperature phase transformation in the Cu2ZnSnS4 (CZTS) films was investigated by laser annealing and low temperature thermal annealing. The Raman measurements show that a-high-power laser annealing could cause a red shift of the Raman scattering peaks of the kesterite (KS) structure and promotes the formation of the partially disordered kesterite (PD-KS) structure in the CZTS films, and the low-temperature thermal annealing only shifts the Raman scattering peak of KS phase by several wavenumber to low frequency and the broads Raman peaks in the low frequency region. Moreover, the above two processes were reversible. The Raman analyses of the CZTS samples prepared under different process show that the PD-KS structure tends to be found at low temperatures and low sulfur vapor pressures. Our results reveal that the control of the phase structure in CZTS films is feasible by adjusting the preparation process of the films. Project supported by the Natural Science Foundation for Youth Fund of Hebei Province, China (Grant No. A2016201087), the Specialized Research Fund for the Doctoral Program of Higher Education of China (Grant No. 20131301120003), and the National Natural Science Foundation of China (Grant Nos. 11504078 and 61504054).

  11. Radioluminescence and thermoluminescence of albite at low temperature

    Energy Technology Data Exchange (ETDEWEB)

    Can, N., E-mail: cannurdogan@yahoo.com [Physics Department, Faculty of Arts and Sciences, Celal Bayar University, 45140 Muradiye-Manisa (Turkey); Garcia-Guinea, J. [Museo Nacional Ciencias Naturales, Jose Gutierrez Abascal 2, Madrid 28006 (Spain); Kibar, R.; Cetin, A.; Ayvacikli, M. [Physics Department, Faculty of Arts and Sciences, Celal Bayar University, 45140 Muradiye-Manisa (Turkey); Townsend, P.D. [Science and Technology, University of Sussex, Brighton BN1 9QH, England (United Kingdom)

    2011-08-15

    Feldspar as an archaeological and geological natural material for dating and retrospective dosimetry is receiving more and more attention because of its useful luminescence properties. In this study, the 25-280 K thermoluminescence (TL) and radioluminescence (RL) spectra in albite, which is a component of the two main feldspar series, the alkali feldspar (Na, K)AlSi{sub 3}O{sub 8} and the plagioclases (NaAlSi{sub 3}O{sub 8}-CaAl{sub 2}Si{sub 2}O{sub 8}) have been presented for aliquots along (001) and (010) crystallographic orientations. There are four main emission bands that are considered to arise from complexes of intrinsic defects linked in larger complexes with impurities such as Na{sup +}, Mn{sup 2+} or Fe{sup 3+} ions. The consequence of their association is to produce different luminescence efficiencies that produce wavelength sensitive TL curves. Radioluminescence data at low temperature for albites is distorted by contributions from the TL sites, even when the RL is run in a cooling cycle. This indicates the potential for a far more general problem for analysis of low temperature RL in insulating materials. - Highlights: > TL and RL spectra in albite were presented for different orientations. > There are 4 emission bands that are considered to arise from complexes of intrinsic. > RL data at low temperature for albite is distorted by contributions from TL sites. > This indicates the potential problem for analysis of low temperature RL.

  12. Dyeing Performance of Soybean Fiber Treated with Low Temperature Plasma

    Institute of Scientific and Technical Information of China (English)

    WANG Li-ming; SHEN Yong; DING Ying; ZHANG Hui-fang

    2006-01-01

    The soybean fiber was treated with low temperature plasma and the dyeing performance of the treated soybean fiber was also researched. The results show that the speed of dyeing and the percentages of balance dyeing have a sharp increase after being treated. So the dyeing temperature and the dosage of acid can be reduced without damaging the bulk fiber structure.

  13. New polymer electrolytes for low temperature fuel cells

    Energy Technology Data Exchange (ETDEWEB)

    Sundholm, F.; Elomaa, M.; Ennari, J.; Hietala, S.; Paronen, M. [Univ. of Helsinki (Finland). Lab. of Polymer Chemistry

    1998-12-31

    Proton conducting polymer membranes for demanding applications, such as low temperature fuel cells, have been synthesised and characterised. Pre-irradiation methods are used to introduce sulfonic acid groups, directly or using polystyrene grafting, in stable, preformed polymer films. The membranes produced in this work show promise for the development of cost-effective, highly conducting membranes. (orig.)

  14. Low Temperature Phonon Properties of Orthorhombic REMnO3

    Science.gov (United States)

    Liu, Zhenxian; Gao, Peng; Chen, Haiyan; Tyson, Trevor A.

    2010-03-01

    We present the temperature dependent phonon spectra of orthorhombic-LuMnO3 and DyMnO3. The temperature dependent phonon spectra results are compared with the XAFS measurement results to probe for structural changes in the low temperature region which may coincide with ferroelectric behavior.

  15. On the Interpretation of Low Temperature Calorimetry Data

    DEFF Research Database (Denmark)

    Kjeldsen, Ane Mette; Geiker, Mette Rica

    2008-01-01

    The effect of selected factors and phenomena on Low Temperature Calorimetry (LTC) results has been investigated, in order to determine the possibilities and limitations of using LTC for characterisation of the porosity of cement-based materials. LTC was carried out on a model material with mono...

  16. Localized temperature stability of low temperature cofired ceramics

    Science.gov (United States)

    Dai, Steven Xunhu

    2013-11-26

    The present invention is directed to low temperature cofired ceramic modules having localized temperature stability by incorporating temperature coefficient of resonant frequency compensating materials locally into a multilayer LTCC module. Chemical interactions can be minimized and physical compatibility between the compensating materials and the host LTCC dielectrics can be achieved. The invention enables embedded resonators with nearly temperature-independent resonance frequency.

  17. LOW-TEMPERATURE STRUCTURE OF SOLID C-70

    NARCIS (Netherlands)

    van Smaalen, Sander; Petricek, Vaclav; de Boer, Jan; Dusek, Michal P.; Verheijen, Marcel A.; Meijer, G.

    1994-01-01

    The structure of the low-temperature phase of hexagonal close-packed (hcp) grown C70 is determined from single-crystal X-ray diffraction at 220 K and 100 K. An ordering of the molecules is found on the orthohexagonal supercell of a hcp structure with symmetry Pbnm. It involves alignment of the molec

  18. Low temperature gaseous nitriding and carburising of stainless steel

    DEFF Research Database (Denmark)

    Christiansen, Thomas; Somers, Marcel A.J.

    2005-01-01

    The response of various austenitic and duplex stainless steel grades to low temperature gaseous nitriding and carburising was investigated. Gaseous nitriding was performed in ammonia/hydrogen mixtures at temperatures ,723 K; gaseous carburising was carried out in carbon monoxide/hydrogen mixtures...

  19. Microstructural Characterization of Low Temperature Gas Nitrided Martensitic Stainless Steel

    DEFF Research Database (Denmark)

    Fernandes, Frederico Augusto Pires; Christiansen, Thomas Lundin; Somers, Marcel A. J.

    2015-01-01

    The present work presents microstructural investigations of the surface zone of low temperature gas nitrided precipitation hardening martensitic stainless steel AISI 630. Grazing incidence X-ray diffraction was applied to investigate the present phases after successive removal of very thin sections...

  20. The 2017 Plasma Roadmap: Low temperature plasma science and technology

    Science.gov (United States)

    Journal of Physics D: Applied Physics published the first Plasma Roadmap in 2012 consisting of the individual perspectives of 16 leading experts in the various sub-fields of low temperature plasma science and technology. The 2017 Plasma Roadmap is the first update of a planned series of periodic upd...

  1. Effective potentials for atom-atom interaction at low temperatures

    OpenAIRE

    Gao, Bo

    2002-01-01

    We discuss the concept and design of effective atom-atom potentials that accurately describe any physical processes involving only states around the threshold. The existence of such potentials gives hope to a quantitative, and systematic, understanding of quantum few-atom and quantum many-atom systems at relatively low temperatures.

  2. 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.

  3. Low-temperature fabricated TFTs on polysilicon stripes

    NARCIS (Netherlands)

    Brunets, I.; Holleman, J.; Kovalgin, A.Y.; Boogaard, A.; Schmitz, J.

    2009-01-01

    This paper presents a novel approach to make highperformance CMOS at low temperatures. Fully functional devices are manufactured using back-end compatible substrate temperatures after the deposition of the amorphous-silicon starting material. The amorphous silicon is pretextured to control the locat

  4. Models of Ballistic Propagation of Heat at Low Temperatures

    Science.gov (United States)

    Kovács, R.; Ván, P.

    2016-09-01

    Heat conduction at low temperatures shows several effects that cannot be described by the Fourier law. In this paper, the performance of various theories is compared in case of wave-like and ballistic propagation of heat pulses in NaF.

  5. Circulator Integrated in Low Temperature Co-fired Ceramics Technology

    NARCIS (Netherlands)

    Dijk, R. van; Bent, G. van der; Ashari, M.; McKay, M.

    2014-01-01

    We present a demonstration of an integrated circulator for TR modules using low temperature co-fired ceramic (LTCC) technology. Two different circulators have been realised to be used in TR modules in two different frequency bands, C-and Ku-band. The circulator is a three-port junction microstrip ty

  6. Low temperature CVD growth of ultrathin carbon films

    Directory of Open Access Journals (Sweden)

    Chao Yang

    2016-05-01

    Full Text Available We demonstrate the low temperature, large area growth of ultrathin carbon films by chemical vapor deposition under atmospheric pressure on various substrates. In particularly, uniform and continuous carbon films with the thickness of 2-5 nm were successfully grown at a temperature as low as 500 oC on copper foils, as well as glass substrates coated with a 100 nm thick copper layer. The characterizations revealed that the low-temperature-grown carbon films consist on few short, curved graphene layers and thin amorphous carbon films. Particularly, the low-temperature grown samples exhibited over 90% transmittance at a wavelength range of 400-750 nm and comparable sheet resistance in contrast with the 1000oC-grown one. This low-temperature growth method may offer a facile way to directly prepare visible ultrathin carbon films on various substrate surfaces that are compatible with temperatures (500-600oC used in several device processing technologies.

  7. Low temperature failure of bulk nanostructured titanium processed by ECAP

    NARCIS (Netherlands)

    Miskuf, J.; Csach, K.; Jurikova, A.; Ocelik, V.; De Hosson, J. Th. M.; Bengus, V. Z.; Tabachnikova, E. D.; Podolskiy, A. V.; Stolyarov, V. V.; Valiev, R. Z.

    2009-01-01

    Low temperature yield stress and the failure nanostructured titanium of commercial purity produced by severe plastic deformation were analysed. The mechanical properties for specimens with average grain size 15 mu m, 0.3 mu m and 0.1 mu m were studied under uniaxial compression with strain rate 4 x

  8. Microbial Degradation of Organic Wastes at Low Temperatures.

    Directory of Open Access Journals (Sweden)

    K.V. Ramana

    2000-10-01

    Full Text Available Microbial degradation of organic wastes mainly comprising animal and human wastes, is drastically reduced at extreme low temperatures. For the biodegradation of these wastes, technological inputs are required from disciplines like microbiology, biochemistry, molecular biology, digester modelling and heat transfer at extreme low temperature climates. Various steps in the process of biodegradation have to be studied to formulate an effective organic waste disposal method. Anaerobic digestion of organic wastes is preferred over aerobic waste treatment method, since it yields biogas as a by-product, which in turn can be utilised for heating the digester contents to increase its efficiency. Furthermore, one of the possibilities that can be explored is the utilisation of high rate anaerobic digesters which maintain temperature by means of artificial heating. It is either met by non-conventional energy sources, such as solar and wind energy, or by expending liquid fuels. In addition, insulation of the digester with polymeric materials and immobilisation of slow growing bacterial population may enhance the digester performance to a great extent. In spite of several developments, inoculum adaptation is considered to be one of the essential steps for low temperature anaerobic digestion to obtain methane as a by-product. With advancements in recombinant DNA technology, it may be possible to increase the efficiency of various microbial population that take part in the anaerobic digestion. However, till date, the options available for low temperature biodegradation are digester insulation, inoculum adaptation, and use of high rate/second-generation digesters.

  9. Challenges in Smart Low-Temperature District Heating Development

    DEFF Research Database (Denmark)

    Li, Hongwei; Wang, Stephen Jia

    2014-01-01

    Previous research and development shows that low temperature district heating (LTDH) system is economic feasible for low energy buildings and buildings at sparse areas. Coupling with reduced network temperature and well-designed district heating (DH) networks, LTDH can reduce network heat loss...

  10. Recent progress in low-temperature silicon detectors

    CERN Document Server

    Abreu, M; Berglund, P; Borchi, E; Borer, K; Bruzzi, M; Buontempo, S; Casagrande, L; Chapuy, S; Cindro, V; D'Ambrosio, N; De Masi, R; Devine, S R H; Dezillie, B; Dierlamm, A; Dimcovski, Zlatomir; Eremin, V; Esposito, A; Granata, V; Grigoriev, E; Grohmann, S; Härkönen, J; Hauler, F; Heijne, Erik H M; Heising, S; Hempel, O; Herzog, R; Janos, S; Jungermann, L; Konorov, I; Li, Z; Lourenço, Carlos; Rato-Mendes, P; Menichelli, D; Mikuz, M; Niinikoski, Tapio O; Pagano, S; Palmieri, V G; Paul, S; Pirollo, S; Pretzl, Klaus; Ruggiero, G; Shea, V O; Smith, K; Solano, B P; Sonderegger, Peter; Sousa, P; Tuominen, E; Verbitskaya, E; Watts, S; Wobst, E; Zavrtanik, M; Da Vià, C; de Boer, Wim

    2003-01-01

    The CERN RD39 Collaboration studies the possibility to extend the detector lifetime in a hostile radiation environment by operating them at low temperatures. The outstanding illustration is the Lazarus effect, which showed a broad operational temperature range around 130 K for neutron irradiated silicon detectors.

  11. A novel electrolytic ignition monopropellant microthruster based on low temperature co-fired ceramic tape technology.

    Science.gov (United States)

    Wu, Ming-Hsun; Yetter, Richard A

    2009-04-07

    A planar 2-D liquid monopropellant microthruster fabricated from low temperature co-fired ceramic tapes and ignited by electrolysis is reported. The volume of the combustion chamber was 820 nL (0.82 mm(3)). Silver electrodes were screen printed and positioned on the top and bottom surfaces of the combustion chamber. A DC voltage potential applied across the electrodes was used to initiate decomposition of hydroxylammonium nitrate (HAN) based liquid monopropellants. A thrust output of 150 mN was obtained using a voltage input of 45 V. Measured ignition energies were as small as 1.9 J. Ignition delays, as short as a few hundred milliseconds, were found dependent on the type of HAN-based propellant and the voltage potential.

  12. 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.

  13. PCl3-C6H6 heterodimers: evidence for Pπ phosphorus bonding at low temperatures.

    Science.gov (United States)

    Ramanathan, N; Sankaran, K; Sundararajan, K

    2016-07-28

    A phosphorous trichloride (PCl3)-benzene (C6H6) heterodimer was generated in a low temperature N2 matrix and was characterized using infrared spectroscopy. The structure of the heterodimer produced in the matrix isolation experiment was discerned through ab initio computations. Computations disclosed that the experimentally detected dimer is stabilized through strong non-covalent phosphorus bonded Pπ interaction, considered as a class of pnicogen bonding. This experimentally unmapped Pπ interaction so far has been reconnoitered using atoms in molecules and natural bond orbital and energy decomposition analyses. The influence of substitutions on both the PCl3 and C6H6 monomeric units of the heterodimer was subsequently examined to understand the strength of Pπ interaction as a result of these substitutions.

  14. Surface Morphology and Microstructure of Zinc Deposit From Imidazole with Zinc Chloride Low Temperature Molten Salt Electrolyte in The Presence of Aluminium Chloride

    Directory of Open Access Journals (Sweden)

    Shanmugasigamani Srinivasan, M. Selvam

    2013-07-01

    Full Text Available Low temperature molten salts have variety of applications in organic synthesis, catalytic processing, batteries and electrode position due to their air and water stability. They have wide potential window for their applications in voltage and temperature and hence there is a possibility to deposit metals which could not be deposited from aqueous electrolytes. Our aim and scope of our research was to deposit zinc from low temperature molten salt electrolyte (LTMS containing zinc salt in the presence of aluminium chloride at different current densities and to qualify the nature of deposits. We could identify the effect of current density on the deposit at low temperature molten salt electrolyte by analysing the nature of deposits using different instrumental techniques. Compact, adherent, dense fine grained deposits of zinc with average grain size of 40-150 nm could be obtained from low temperature molten salt electrolyte. (LTMS

  15. Low temperature regeneration of activated carbons using microwaves: revising conventional wisdom.

    Science.gov (United States)

    Calışkan, E; Bermúdez, J M; Parra, J B; Menéndez, J A; Mahramanlıoğlu, M; Ania, C O

    2012-07-15

    The purpose of this work was to explore the application of microwaves for the low temperature regeneration of activated carbons saturated with a pharmaceutical compound (promethazine). Contrary to expectations, microwave-assisted regeneration did not lead to better results than those obtained under conventional electric heating. At low temperatures the regeneration was incomplete either under microwave and conventional heating, being this attributed to the insufficient input energy. At mild temperatures, a fall in the adsorption capacity upon cycling was obtained in both devices, although this was much more pronounced for the microwave. These results contrast with previous studies on the benefits of microwaves for the regeneration of carbon materials. The fall in the adsorption capacity after regeneration was due to the thermal cracking of the adsorbed molecules inside the carbon porous network, although this effect applies to both devices. When microwaves are used, along with the thermal heating of the carbon bed, a fraction of the microwave energy seemed to be directly used in the decomposition of promethazine through the excitation of the molecular bonds by microwaves (microwave-lysis). These results point out that the nature of the adsorbate and its ability to interact with microwave are key factors that control the application of microwaves for regeneration of exhausted activated carbons.

  16. Trends in low-temperature water–gas shift reactivity on transition metals

    DEFF Research Database (Denmark)

    Schumacher, Nana Maria Pii; Boisen, Astrid; Dahl, Søren;

    2005-01-01

    Low-temperature water–gas shift reactivity trends on transition metals were investigated with the use of a microkinetic model based on a redox mechanism. It is established that the adsorption energies for carbon monoxide and oxygen can describe to a large extent changes in the remaining activation...... and adsorption energies through linear correlations. In comparisons with experimental data it is found that the model predicts well the order of catalytic activities for transition metals, although it fails to quantitatively describe the experimental data. This discrepancy could be due to the assumption...... that the redox mechanism dominates and to the neglect of adsorbate interactions, which play an important role at high coverages. The model predicts that the activity of copper can be improved by increasing the strengths with which carbon monoxide and oxygen are bonded to the surface, thus suggesting possible...

  17. Low-temperature conversion of high-moisture biomass: Topical report, January 1984--January 1988

    Energy Technology Data Exchange (ETDEWEB)

    Sealock, L.J. Jr.; Elliott, D.C.; Butner, R.S.; Neuenschwander, G.G.

    1988-10-01

    Pacific Northwest Laboratory (PNL) is developing a low-temperature, catalytic process that converts high-moisture biomass feedstocks and other wet organic substances to useful gaseous and liquid fuels. The advantage of this process is that it works without the need for drying or dewatering the feedstock. Conventional thermal gasification processes, which require temperatures above 750/degree/C and air or oxygen for combustion to supply reaction heat, generally cannot utilize feedstocks with moisture contents above 50 wt %, as the conversion efficiency is greatly reduced as a result of the drying step. For this reason, anaerobic digestion or other bioconversion processes traditionally have been used for gasification of high-moisture feedstocks. However, these processes suffer from slow reaction rates and incomplete carbon conversion. 50 refs., 21 figs., 22 tabs.

  18. Organometallic Complexes Anchored to Conductive Carbon for Electrocatalytic Oxidation of Methane at Low Temperature.

    Science.gov (United States)

    Joglekar, Madhura; Nguyen, Vinh; Pylypenko, Svitlana; Ngo, Chilan; Li, Quanning; O'Reilly, Matthew E; Gray, Tristan S; Hubbard, William A; Gunnoe, T Brent; Herring, Andrew M; Trewyn, Brian G

    2016-01-13

    Low-temperature direct methane fuel cells (DMEFCs) offer the opportunity to substantially improve the efficiency of energy production from natural gas. This study focuses on the development of well-defined platinum organometallic complexes covalently anchored to ordered mesoporous carbon (OMC) for electrochemical oxidation of methane in a proton exchange membrane fuel cell at 80 °C. A maximum normalized power of 403 μW/mg Pt was obtained, which was 5 times higher than the power obtained from a modern commercial catalyst and 2 orders of magnitude greater than that from a Pt black catalyst. The observed differences in catalytic activities for oxidation of methane are linked to the chemistry of the tethered catalysts, determined by X-ray photoelectron spectroscopy. The chemistry/activity relationships demonstrate a tangible path for the design of electrocatalytic systems for C-H bond activation that afford superior performance in DMEFC for potential commercial applications.

  19. Platinum-based nanocomposite electrodes for low-temperature solid oxide fuel cells with extended lifetime

    Science.gov (United States)

    Lee, Yoon Ho; Cho, Gu Young; Chang, Ikwhang; Ji, Sanghoon; Kim, Young Beom; Cha, Suk Won

    2016-03-01

    Due to its high catalytic activity and convenient fabrication procedure that uses physical vapor deposition (PVD), nanofabricated platinum (Pt) is widely used for low temperature operating solid oxide fuel cells (LT-SOFC). However, the poor thermal stability of nanofabricated Pt accelerates cell performance degradation. To solve this problem, we apply a thermal barrier coating and use the dispersion hardening process for the nanofabrication of Pt by sputter device. Through morphological and electrochemical data, GDC modified nano-porous Pt electrodes shows improved performance and thermal stability at the operating temperature of 500 °C. While the peak power density of pure Pt sample is 6.16 mW cm-2 with a performance degradation of 43% in an hour, the peak power density of the GDC modified Pt electrodes are in range of 7.42-7.91 mW cm-2 with a 7-16% of performance degradation.

  20. Interpretation of low-temperature data part 4: The low-temperature magnetic transition of monoclinic pyrrhotite

    NARCIS (Netherlands)

    Rochette, P.; Fillion, G.; Dekkers, M.J.

    2011-01-01

    Use of low temperature (LT) magnetic transitions to identify magnetic minerals that carry a remanence – either natural or laboratory-induced – at room temperature, is a classic tool in rock magnetism (e.g. Nagata et al., 1964; Kosterov, 2007). This particularly applies to magnetite (Verwey transitio

  1. 不同方法制备碳载金催化剂对臭氧的催化分解%Catalytic Activity of Au Supported on Activated Carbon Catalyst Preparing with Different Methods for Ozone Decomposition

    Institute of Scientific and Technical Information of China (English)

    张博; 徐九华; 李宏煦; 史蕊

    2011-01-01

    采用浸渍法和溶胶负载法制备以改性活性碳为载体以纳米金为活性组分的催化剂,通过BET,SEM和XPS表征制备方法对催化剂比表面积、孔隙结构、表面形貌及表面元素组成的影响,测试催化剂在室温下对低浓度臭氧的催化分解性能.结果显示,在室温,相对湿度为45±5%,空速为96000h(-1).臭氧初始浓度为50mg/m3,气体与催化剂的接触时间为0.04s的条件下,在1200min时采用浸渍法制备的催化剂对臭氧的分解率为85%,而溶胶负载法制备的催化剂此时对臭氧的分解效率仍在94%以上.采用溶胶负载法制备的催化剂纳米金颗粒粒径更小、更均匀,在催化剂表面的覆盖率更大是其催化活性更高的主要原因.%The catalysts of nano-particle Au supported by modified activated carbon are prepared with the methods of impregnation and sol-immobilized, and characterized by BET, SEM and XPS to consider the influence of preparation method to its specific surface area, pore structure, surface topography and composition.The catalytic activity for low-level ozone decomposition at ambient temperature of the catalysts is evaluated.The results show that under the condition of 50mg/m3 ozone in air, space velocity 96000 h-1, relative humidity 45 ±5% , contact time 0.04s and ambient temperature, the ozone removal ratio with the catalyst prepared by impregnation method is at 85% within 1200min, however, the ozone removal ratio with the catalyst by sol-immobilized method could be maintained above 94%.This is due to the reason that the supported gold nanoparticles in the catalyst prepared with sol-immobilized method are much smaller and more uniformly dispersed on the activated carbon, exhibit the higher fraction of coverage.

  2. 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.

  3. Analysis of Low-Temperature Utilization of Geothermal Resources

    Energy Technology Data Exchange (ETDEWEB)

    Anderson, Brian

    2015-06-30

    Full realization of the potential of what might be considered “low-grade” geothermal resources will require that we examine many more uses for the heat than traditional electricity generation. To demonstrate that geothermal energy truly has the potential to be a national energy source we will be designing, assessing, and evaluating innovative uses for geothermal-produced water such as hybrid biomass-geothermal cogeneration of electricity and district heating and efficiency improvements to the use of cellulosic biomass in addition to utilization of geothermal in district heating for community redevelopment projects. The objectives of this project were: 1) to perform a techno-economic analysis of the integration and utilization potential of low-temperature geothermal sources. Innovative uses of low-enthalpy geothermal water were designed and examined for their ability to offset fossil fuels and decrease CO2 emissions. 2) To perform process optimizations and economic analyses of processes that can utilize low-temperature geothermal fluids. These processes included electricity generation using biomass and district heating systems. 3) To scale up and generalize the results of three case study locations to develop a regionalized model of the utilization of low-temperature geothermal resources. A national-level, GIS-based, low-temperature geothermal resource supply model was developed and used to develop a series of national supply curves. We performed an in-depth analysis of the low-temperature geothermal resources that dominate the eastern half of the United States. The final products of this study include 17 publications, an updated version of the cost estimation software GEOPHIRES, and direct-use supply curves for low-temperature utilization of geothermal resources. The supply curves for direct use geothermal include utilization from known hydrothermal, undiscovered hydrothermal, and near-hydrothermal EGS resources and presented these results at the Stanford

  4. Experiments on Quantum Hall Topological Phases in Ultra Low Temperatures

    Energy Technology Data Exchange (ETDEWEB)

    Du, Rui-Rui [Rice Univ., Houston, TX (United States). Dept. of Physics and Astronomy

    2015-02-14

    This project is to cool electrons in semiconductors to extremely low temperatures and to study new states of matter formed by low-dimensional electrons (or holes). At such low temperatures (and with an intense magnetic field), electronic behavior differs completely from ordinary ones observed at room temperatures or regular low temperature. Studies of electrons at such low temperatures would open the door for fundamental discoveries in condensed matter physics. Present studies have been focus on topological phases in the fractional quantum Hall effect in GaAs/AlGaAs semiconductor heterostructures, and the newly discovered (by this group) quantum spin Hall effect in InAs/GaSb materials. This project consists of the following components: 1) Development of efficient sample cooling techniques and electron thermometry: Our goal is to reach 1 mK electron temperature and reasonable determination of electron temperature; 2) Experiments at ultra-low temperatures: Our goal is to understand the energy scale of competing quantum phases, by measuring the temperature-dependence of transport features. Focus will be placed on such issues as the energy gap of the 5/2 state, and those of 12/5 (and possible 13/5); resistive signature of instability near 1/2 at ultra-low temperatures; 3) Measurement of the 5/2 gaps in the limit of small or large Zeeman energies: Our goal is to gain physics insight of 5/2 state at limiting experimental parameters, especially those properties concerning the spin polarization; 4) Experiments on tuning the electron-electron interaction in a screened quantum Hall system: Our goal is to gain understanding of the formation of paired fractional quantum Hall state as the interaction pseudo-potential is being modified by a nearby screening electron layer; 5) Experiments on the quantized helical edge states under a strong magnetic field and ultralow temperatures: our goal is to investigate both the bulk and edge states in a quantum spin Hall insulator under time

  5. Low temperature SCR of NO with catalysts prepared by modified ACF loading Mn and Ce: effects of modification method.

    Science.gov (United States)

    Li, Ping; Lu, Pei; Zhai, Yunbo; Li, Caiting; Chen, Ting; Qing, Renpeng; Zhang, Wei

    2015-01-01

    Achievement of a higher NOx conversion ratio in selective catalytic reduction (SCR) at low temperature is challenging. In this work, pure activated carbon fibres (ACFs) were modified with different ratios of H2O (g), NaOH, CO2 and HNO3, respectively (named as modified ACF). The chemical and physical properties of modified ACFs were identified by Brunauer-Emmett-Teller, X-ray diffraction, Fourier transform infrared spectroscopy and X-ray photoelectron spectroscopy methods. The NOx conversion ratio of ACF was improved from 56.1% to 82.4% at 80°C after modification with 30% (mass ratio) NaOH. These modified ACFs were further loaded with the mixture of MnO2 and CeO2 in the form of metal salt solutions (named as Mn0.5Ce0.5O2/modified ACF). The NOx conversion ratio of 30% SHACF remained similar at 80°C but was increased from 60.0% to 98.5% at 360°C after loading with Mn and Ce, which showed the best performance in SCR of NOx at low temperature. It could be seen that ACF delivered higher performance in low temperature SCR after being modified with the aforementioned reactants and further loading with metals. Based on chemical and physical characterization and the performance of the catalysts, the reasons for different performances of these catalysts in low temperature SCR are discussed.

  6. Surface modification of oleylamine-capped Ag-Cu nanoparticles to fabricate low-temperature-sinterable Ag-Cu nanoink

    Science.gov (United States)

    Kim, Na Rae; Jong Lee, Yung; Lee, Changsoo; Koo, Jahyun; Lee, Hyuck Mo

    2016-08-01

    By treating oleylamine (OA)-capped Ag-Cu nanoparticles with tetramethylammonium hydroxide (TMAH), we obtained metal nanoparticles that are suspended in polar solvents and sinterable at low temperatures. The simple process with ultra sonication enables synthesis of monodispersed and high purity nanoparticles in an organic base, where the resulting nanoparticles are dispersible in polar solvents such as ethanol and isopropyl alcohol. To investigate the surface characteristics, we conducted Fourier-transform infrared and zeta-potential analyses. After thermal sintering at 200 °C, which is approximately 150 °C lower than the thermal decomposition temperature of OA, an electrically conductive thin film was obtained. Electrical resistivity measurements of the TMAH-treated ink demonstrate that surface modified nanoparticles have a low resistivity of 13.7 × 10-6 Ω cm. These results confirm the prospects of using low-temperature sinterable nanoparticles as the electrode layer for flexible printed electronics without damaging other stacked polymer layers.

  7. Low-temperature desulfurizing reaction with Cu-containing sorbents

    Energy Technology Data Exchange (ETDEWEB)

    Yi, Kwang Bok; Choi, Eun Mi; Song, Yi Keun; Rhee, Young Woo [Department of Chemical Engineering, Chungnam National University, Taejeon (Korea)

    1999-10-01

    The sorbents containing Cu O as an active material were prepared and their effectiveness in desulfurization was investigated at low temperatures(350-550 degree C). M.I.5 and MnO{sub 2} were chosen as additives and SiO{sub 2} was chosen as support material. In the low temperature regeneration reaction, sulfate was formed, which could not be decomposed until regeneration temperature reached 650 degree C. Sulfidation reaction rate decreased as calcination temperature increased. Promoting effect of MoO{sub 3} was not observed throughout the sulfidation/regeneration reaction. When SiO{sub 2} content was below 25% of sorbents composition, sulfur loading of above 10% could be obtained. Mass transfer inhibition by sulfiding gas was observed for the sorbents containing no SiO{sub 2}. 9 refs., 9 figs., 4 tabs.

  8. HPGe detectors for low-temperature nuclear orientation

    CERN Document Server

    Zakoucky, D; Vénos, D; Golovko, V V; Kraev, I S; Phalet, T; Schuurmans, P; Severijns, N; Vereecke, B; Versyck, S

    2004-01-01

    Using the low-temperature nuclear orientation (LTNO) technique one can study various interesting properties of atomic nuclei and nuclear decay which can be deduced from the measurements of the angular distributions of charged particles emitted during the decay. However, the use of particle detectors working in conditions of LTNO devices (which are generally not available commercially) is a necessary precondition for the realization of these experiments. Planar HPGe detectors for detection of charged particles at "liquid helium" temperatures were developed and produced at NPI Rez. Relatively simple technology using vacuum evaporation and diffusion was employed. The performance of detectors at low temperatures was tested and their characteristics measured in a testing cryostat before using them in real experiments. The HPGe detectors were extensively used in a whole range of LTNO experiments with various physical objectives - in offline (IKS Leuven) as well as online (CERN-ISOLDE, Louvain-la- Neuve - LISOL) exp...

  9. Low Temperature Heat Capacity of a Severely Deformed Metallic Glass

    Science.gov (United States)

    Bünz, Jonas; Brink, Tobias; Tsuchiya, Koichi; Meng, Fanqiang; Wilde, Gerhard; Albe, Karsten

    2014-04-01

    The low temperature heat capacity of amorphous materials reveals a low-frequency enhancement (boson peak) of the vibrational density of states, as compared with the Debye law. By measuring the low-temperature heat capacity of a Zr-based bulk metallic glass relative to a crystalline reference state, we show that the heat capacity of the glass is strongly enhanced after severe plastic deformation by high-pressure torsion, while subsequent thermal annealing at elevated temperatures leads to a significant reduction. The detailed analysis of corresponding molecular dynamics simulations of an amorphous Zr-Cu glass shows that the change in heat capacity is primarily due to enhanced low-frequency modes within the shear band region.

  10. Low-temperature random matrix theory at the soft edge

    Energy Technology Data Exchange (ETDEWEB)

    Edelman, Alan [Department of Mathematics, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139 (United States); Persson, Per-Olof [Department of Mathematics, University of California, Berkeley, California 94720 (United States); Sutton, Brian D. [Department of Mathematics, Randolph-Macon College, Ashland, Virginia 23005 (United States)

    2014-06-15

    “Low temperature” random matrix theory is the study of random eigenvalues as energy is removed. In standard notation, β is identified with inverse temperature, and low temperatures are achieved through the limit β → ∞. In this paper, we derive statistics for low-temperature random matrices at the “soft edge,” which describes the extreme eigenvalues for many random matrix distributions. Specifically, new asymptotics are found for the expected value and standard deviation of the general-β Tracy-Widom distribution. The new techniques utilize beta ensembles, stochastic differential operators, and Riccati diffusions. The asymptotics fit known high-temperature statistics curiously well and contribute to the larger program of general-β random matrix theory.

  11. Partial Discharge in Capacitor Model at Low Temperature

    Directory of Open Access Journals (Sweden)

    P. Rain

    2009-01-01

    Full Text Available The partial discharge plays an important role in the ageing and the rupture process of solid or mixed insulation systems. Ithas been recognized that the failure of this insulation can be joined to the presence of partial discharge often in inclusionssparkling. Liquid filled cavities can be considered as the most likely defects that can exist in capacitors. In this paper wedescribe the partial discharge evolution at low temperatures in all-PP film capacitors according to the time and the appliedvoltage. We distinguish two regimes of discharges for all the range of temperature and the low temperatures encourage thebreakdown of capacitors at weak voltage, we assign this phenomenon to the increase of the viscosity of filling liquid.

  12. 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.

  13. Cubic ideal ferromagnets at low temperature and weak magnetic field

    Science.gov (United States)

    Hofmann, Christoph P.

    2017-04-01

    The low-temperature series for the free energy density, pressure, magnetization and susceptibility of cubic ideal ferromagnets in weak external magnetic fields are discussed within the effective Lagrangian framework up to three loops. The structure of the simple, body-centered, and face-centered cubic lattice is taken into account explicitly. The expansion involves integer and half-integer powers of the temperature. The corresponding coefficients depend on the magnetic field and on low-energy effective constants that can be expressed in terms of microscopic quantities. Our formulas may also serve as efficiency or consistency check for other techniques like Green's function methods, where spurious terms in the low-temperature expansion have appeared. We explore the sign and magnitude of the spin-wave interaction in the pressure, magnetization and susceptibility, and emphasize that our effective field theory approach is fully systematic and rigorous.

  14. Low temperature magnetoresistance measurements on bismuth nanowire arrays.

    Science.gov (United States)

    Kaiser, Ch; Weiss, G; Cornelius, T W; Toimil-Molares, M E; Neumann, R

    2009-05-20

    We present low temperature resistance R(T) and magnetoresistance measurements for Bi nanowires with diameters between 100 and 500 nm, which are close to being single-crystalline. The nanowires were fabricated by electrochemical deposition in pores of polycarbonate membranes. R(T) varies as T(2) in the low temperature range 1.5 Kwire diameter. An unexpected effect is observed in R(T) when a magnetic field is present. It can be related to the temperature dependence of the magnetoresistance. The transverse magnetoresistance of all samples shows a clear B(1.5) variation. Its size depends strongly on the diameter of the wires but only weakly on temperature. Finally, a steplike increase in the magnetoresistance of our sample with a wire diameter of 100 nm was found and this might be attributed to a transition from one-dimensional to three-dimensional localization.

  15. Mesoscopic near-field radiative heat transfer at low temperatures

    Science.gov (United States)

    Maasilta, Ilari; Geng, Zhuoran; Chaudhuri, Saumyadip; Koppinen, Panu

    2015-03-01

    Near-field radiative heat transfer has mostly been discussed at room temperatures and/or macroscopic scale geometries. Here, we discuss our recent theoretical and experimental advances in understanding near-field transfer at ultra-low temperatures below 1K. As the thermal wavelengths increase with lowering temperature, we show that with sensitive tunnel junction bolometers it is possible to study near-field transfer up to distances ~ 10 μm currently, even though the power levels are low. In addition, these type of experiments correspond to the extreme near-field limit, as the near-field region starts at ~ mm distances at 0.1 K, and could have theoretical power enhancement factors of the order of 1010. Preliminary results on heat transfer between two parallel metallic wires are presented. We also comment on possible areas were such heat transfer might be relevant, such as densely packed arrays of low-temperature detectors.

  16. 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.

  17. Study on low temperature plasma driven permeation of hydrogen

    Energy Technology Data Exchange (ETDEWEB)

    Takizawa, Masayuki [Japan Atomic Energy Research Inst., Tokai, Ibaraki (Japan). Tokai Research Establishment

    1998-03-01

    It is one of the most important problem in PWI of fusion devices from the point of view of tritium leakage that hydrogen diffuses in the wall of the device and permeates through it, which results in hydrogen being released to the coolant side. In this study, plasma driven permeation experiments were carried out with several kinds of metal membranes in the low temperature plasma where ionic and atomic hydrogen as well as electron existed in order to survey PDP mechanism from the many view points. In addition, incident flux rate from the plasma to the membrane surface was evaluated by calculation analysis. As a result the mechanism of low temperature PDP was found out and described as PDP models. The simulation of the membrane pump system was executed and the system performance was estimated with the models. (author). 135 refs.

  18. Quantum simulation of low-temperature metallic liquid hydrogen.

    Science.gov (United States)

    Chen, Ji; Li, Xin-Zheng; Zhang, Qianfan; Probert, Matthew I J; Pickard, Chris J; Needs, Richard J; Michaelides, Angelos; Wang, Enge

    2013-01-01

    The melting temperature of solid hydrogen drops with pressure above ~65 GPa, suggesting that a liquid state might exist at low temperatures. It has also been suggested that this low-temperature liquid state might be non-molecular and metallic, although evidence for such behaviour is lacking. Here we report results for hydrogen at high pressures using ab initio methods, which include a description of the quantum motion of the protons. We determine the melting temperature as a function of pressure and find an atomic solid phase from 500 to 800 GPa, which melts at metallic atomic liquid is stable at temperatures as low as 50 K. The quantum motion of the protons is critical to the low melting temperature reported, as simulations with classical nuclei lead to considerably higher melting temperatures of ~300 K across the entire pressure range considered.

  19. Low-temperature creep of austenitic stainless steels

    Science.gov (United States)

    Reed, R. P.; Walsh, R. P.

    2017-09-01

    Plastic deformation under constant load (creep) in austenitic stainless steels has been measured at temperatures ranging from 4 K to room temperature. Low-temperature creep data taken from past and unreported austenitic stainless steel studies are analyzed and reviewed. Creep at cryogenic temperatures of common austenitic steels, such as AISI 304, 310 316, and nitrogen-strengthened steels, such as 304HN and 3116LN, are included. Analyses suggests that logarithmic creep (creep strain dependent on the log of test time) best describe austenitic stainless steel behavior in the secondary creep stage and that the slope of creep strain versus log time is dependent on the applied stress/yield strength ratio. The role of cold work, strain-induced martensitic transformations, and stacking fault energy on low-temperature creep behavior is discussed. The engineering significance of creep on cryogenic structures is discussed in terms of the total creep strain under constant load over their operational lifetime at allowable stress levels.

  20. Low temperature magnetic characterisation of fire ash residues

    Science.gov (United States)

    Peters, C.; Thompson, R.; Harrison, A.; Church, M. J.

    Fire ash is ideally suited to mineral magnetic studies. Both modern (generated by controlled burning experiments) and archaeological ash deposits have been studied, with the aim of identifying and quantifying fuel types used in prehistory. Low temperature magnetic measurements were carried out on the ash samples using an MPMS 2 SQUID magnetometer. The low temperature thermo-remanence cooling curves of the modern ash display differences between fuel sources. Wood and well-humified peat ash display an increase in remanence with cooling probably related to a high superparamagnetic component, consistent with room temperature frequency dependent susceptibilities of over 7%. In comparison fibrous-upper peat and peat turf display an unusual decrease in remanence, possibly due to an isotropic point of grains larger than superparamagnetic in size. The differences have been successfully utilised in unmixing calculations to quantify fuel components within four archaeological deposits from the Northern and Western Isles of Scotland.

  1. Calorimetric Measurements at Low Temperatures in Toluene Glass and Crystal

    Science.gov (United States)

    Alvarez-Ney, C.; Labarga, J.; Moratalla, M.; Castilla, J. M.; Ramos, M. A.

    2017-04-01

    The specific heat of toluene in glass and crystal states has been measured both at low temperatures down to 1.8 K (using the thermal relaxation method) and in a wide temperature range up to the liquid state (using a quasiadiabatic continuous method). Our measurements therefore extend earlier published data to much lower temperatures, thereby allowing to explore the low-temperature "glassy anomalies" in the case of toluene. Surprisingly, no indication of the existence of tunneling states is found, at least within the temperature range studied. At moderate temperatures, our data either for the glass or for the crystal show good agreement with those found in the literature. Also, we have been able to prepare bulk samples of toluene glass by only doping with 2% mol ethanol instead of with higher impurity doses used by other authors.

  2. Apparatus for low temperature thermal desorption spectroscopy of portable samples

    Science.gov (United States)

    Stuckenholz, S.; Büchner, C.; Ronneburg, H.; Thielsch, G.; Heyde, M.; Freund, H.-J.

    2016-04-01

    An experimental setup for low temperature thermal desorption spectroscopy (TDS) integrated in an ultrahigh vacuum-chamber housing a high-end scanning probe microscope for comprehensive multi-tool surface science analysis is described. This setup enables the characterization with TDS at low temperatures (T > 22 K) of portable sample designs, as is the case for scanning probe optimized setups or high-throughput experiments. This combination of techniques allows a direct correlation between surface morphology, local spectroscopy, and reactivity of model catalysts. The performance of the multi-tool setup is illustrated by measurements of a model catalyst. TDS of CO from Mo(001) and from Mo(001) supported MgO thin films were carried out and combined with scanning tunneling microscopy measurements.

  3. Low temperature doping of ZnO nanostructures

    Institute of Scientific and Technical Information of China (English)

    M.A.THOMAS; H.KANDEL; Y.C.SOO

    2009-01-01

    Doping of ZnO nanostructures was investigated by using a low temperature electrochemical process. Various dopant materials have been studied, including transition metals, group I, and group VII elements. The structure, composition, and optical properties of the doped ZnO nanostructures were analyzed by scanning electron microscopy, energy dispersive X-ray spectroscopy, photoluminescence, and x-ray diffraction. It was demonstrated that dopant elements were incorporated into the ZnO structures. The effects of dopant incorporation on the structure and properties of ZnO were also investigated. This low temperature approach is compatible with current micro-fabrication techniques and promising for large-scale production of doped ZnO nanostructures for optical and electronic applications.

  4. Glass transition and heavy oil dynamics at low temperature

    Energy Technology Data Exchange (ETDEWEB)

    Abivin, P.; Indo, K.; Cheng, Y.; Freed, D.; Taylor, S. D. [Schlumberger (Canada)], email: PAbivin@slb.com

    2011-07-01

    In the oil industry, the viscosity of crude oils is a key factor as it affects market value, field developments and the design of production strategies. In heavy oils, a glass transition occurs and previous work related this to oil's temperature-viscosity behavior. This study aimed at better characterizing heavy oil dynamics and the temperature dependency of viscosity. Experiments were conducted with differential scanning calorimetry and shear rate sweeps on heavy oils from Asia, South America and North America over a wide range of temperatures to measure their viscosities and characterize their glass transition. The glass transition was observed at around 210K and results showed that the Arrhenius model does not fit the experimental data at low temperatures but the WLF model does. This research provided a better understanding of heavy oil dynamics but further work is required to explain the viscosity-temperature behavior of heavy oils at low temperatures.

  5. NATO Advanced Study Institute on Low Temperature Molecular Spectroscopy

    CERN Document Server

    1996-01-01

    Molecular spectroscopy has achieved rapid and significant progress in recent years, the low temperature techniques in particular having proved very useful for the study of reactive species, phase transitions, molecular clusters and crystals, superconductors and semiconductors, biochemical systems, astrophysical problems, etc. The widening range of applications has been accompanied by significant improvements in experimental methods, and low temperature molecular spectroscopy has been revealed as the best technique, in many cases, to establish the connection between experiment and theoretical calculations. This, in turn, has led to a rapidly increasing ability to predict molecular spectroscopic properties. The combination of an advanced tutorial standpoint with an emphasis on recent advances and new perspectives in both experimental and theoretical molecular spectroscopy contained in this book offers the reader insight into a wide range of techniques, particular emphasis being given to supersonic jet and matri...

  6. Low-temperature strain gauges based on silicon whiskers

    Directory of Open Access Journals (Sweden)

    Druzhinin A. A.

    2008-08-01

    Full Text Available To create low-temperature strain gauges based on p-type silicon whiskers tensoresistive characteristics of these crystals in 4,2—300 K temperature range were studied. On the basis of p-type Si whiskers with different resistivity the strain gauges for different materials operating at cryogenic temperatures with extremely high gauge factor at 4,2 K were developed, as well as strain gauges operating at liquid helium temperatures in high magnetic fields.

  7. 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 ...

  8. Improving the Performance of Lithium Ion Batteries at Low Temperature

    Energy Technology Data Exchange (ETDEWEB)

    Trung H. Nguyen; Peter Marren; Kevin Gering

    2007-04-20

    The ability for Li-ion batteries to operate at low temperatures is extremely critical for the development of energy storage for electric and hybrid electric vehicle technologies. Currently, Li-ion cells have limited success in operating at temperature below –10 deg C. Electrolyte conductivity at low temperature is not the main cause of the poor performance of Li-ion cells. Rather the formation of a tight interfacial film between the electrolyte and the electrodes has often been an issue that resulted in a progressive capacity fading and limited discharge rate capability. The objective of our Phase I work is to develop novel electrolytes that can form low interfacial resistance solid electrolyte interface (SEI) films on carbon anodes and metal oxide cathodes. From the results of our Phase I work, we found that the interfacial impedance of Fluoro Ethylene Carbonate (FEC) electrolyte at the low temperature of –20degC is astonishingly low, compared to the baseline 1.2M LiPFEMC:EC:PC:DMC (10:20:10:60) electrolyte. We found that electrolyte formulations with fluorinated carbonate co-solvent have excellent film forming properties and better de-solvation characteristics to decrease the interfacial SEI film resistance and facilitate the Li-ion diffusion across the SEI film. The very overwhelming low interfacial impedance for FEC electrolytes will translate into Li-ion cells with much higher power for cold cranking and high Regen/charge at the low temperature. Further, since the SEI film resistance is low, Li interaction kinetics into the electrode will remain very fast and thus Li plating during Regen/charge period be will less likely to happen.

  9. Low-temperature Raman spectra of L-histidine crystal

    CERN Document Server

    De Sousa, G P; Filho, J Mendes; Melo, F E A; Lima, C L

    2013-01-01

    We present a Raman spectroscopy investigation of the vibrational properties of L-histidine crystals at low temperatures. The temperature dependence of the spectra show discontinuities at 165 K, which we identify with modifications in the bonds associated to both the NH3+ and CO2- motifs indicative of a conformational phase transition that changes the intermolecular bonds. Additional evidence of such a phase transition was provided by differential scanning calorimetry measurements, which identified an enthalpic anomaly at ~165 K.

  10. Effects of low temperature on properties of structural steels

    Institute of Scientific and Technical Information of China (English)

    Yanmin Wu; Yuanqing Wang; Yongjiu Shi; Jianjing Jiang

    2004-01-01

    The experiments were carried out to measure the mechanical properties of three grades of structural steels (Q235A, 16Mn and Q390E steel ) at low temperature. It was shown that the strength of the steels increases while the plasticity and toughness decrease as temperature drops. In the transitional area the toughness drops rapidly with temperature. Among the three structural steels,Q390E steel has the best toughness and the lowest sensitivity.

  11. Gaining new insight into low-temperature aqueous photochemical solution deposited ferroelectric PbTiO{sub 3} films

    Energy Technology Data Exchange (ETDEWEB)

    De Dobbelaere, Christopher, E-mail: christopher.dedobbelaere@uhasselt.be [Hasselt University, Institute for Materials Research, Inorganic and Physical Chemistry, B-3500, Hasselt (Belgium); Calzada, M. Lourdes; Bretos, Iñigo; Jiménez, Ricardo; Ricote, Jesús [Instituto de Ciencia de Materiales de Madrid (ICMM-CSIC), Cantoblanco, E-28049, Madrid (Spain); Hadermann, Joke [University of Antwerp, Department of Physics, EMAT, B-2020, Antwerp (Belgium); Hardy, An [Hasselt University, Institute for Materials Research, Inorganic and Physical Chemistry, B-3500, Hasselt (Belgium); IMEC vzw, Division IMOMEC, B-3590, Diepenbeek (Belgium); Van Bael, Marlies K., E-mail: marlies.vanbael@uhasselt.be [Hasselt University, Institute for Materials Research, Inorganic and Physical Chemistry, B-3500, Hasselt (Belgium); IMEC vzw, Division IMOMEC, B-3590, Diepenbeek (Belgium)

    2016-05-01

    The nature of the low-temperature photochemical assisted formation process of ferroelectric lead titanate (PbTiO{sub 3}) films is studied in the present work. Films are obtained by the deposition of an aqueous solution containing citric acid based (citrato) metal ion complexes with intrinsic UV activity. This UV activity is crucial for the aqueous photochemical solution deposition (aqueous PCSD) route being used. UV irradiation enhances the early decomposition of organics and results in improved electrical properties for the crystalline oxide film, even if the film is crystallized at low temperature. GATR-FTIR shows that UV irradiation promotes the decomposition of organic precursor components, resulting in homogeneous films if applied in the right temperature window during film processing. The organic content, morphology and crystallinity of the irradiated films, achieved at different processing atmospheres and temperatures, is studied and eventually correlated to the functional behavior of the obtained films. This is an important issue, as crystalline films obtained at low temperatures often lack ferroelectric responses. In this work, the film prepared in pure oxygen at the very low temperature of 400 °C and after an optimized UV treatment presents a significant remanent polarization value of P{sub r} = 8.8 μC cm{sup −2}. This value is attributed to the better crystallinity, the larger grain size and the reduced porosity obtained thanks to the early film crystallization effectively achieved through the UV treatment in oxygen. - Highlights: • Precursor chemistry enables the UV assisted film deposition process. • PbTiO3 films with improved ferroelectric response and crystallinity are obtained. • UV active components are formed during the whole film formation process. • Perovskite, ferroelectric active PbTiO3 films are formed at 400 °C. • Oxide films can be prepared at reduced temperature.

  12. Oxygen isotopic composition of low-temperature authigenic clinoptilolite

    Science.gov (United States)

    Nähr, T.; Botz, R.; Bohrmann, G.; Schmidt, M.

    1998-08-01

    Oxygen isotope ratios were obtained from authigenic clinoptilolites from Barbados Accretionary Complex, Yamato Basin, and Exmouth Plateau sediments (ODP Sites 672, 797, and 762) in order to investigate the isotopic fractionation between clinoptilolite and pore water at early diagenetic stages and low temperatures. Dehydrated clinoptilolites display isotopic ratios for the zeolite framework ( δ18O f) that extend from +18.7‰ to +32.8‰ (vs. SMOW). In combination with associated pore water isotope data, the oxygen isotopic fractionation between clinoptilolite and pore fluids could be assessed in the temperature range from 25°C to 40°C. The resulting fractionation factors of 1.032 at 25°C and 1.027 at 40°C are in good agreement with the theoretically determined oxygen isotope fractionation between clinoptilolite and water. Calculations of isotopic temperatures illustrate that clinoptilolite formation occurred at relatively low temperatures of 17°C to 29°C in Barbados Ridge sediments and at 33°C to 62°C in the Yamato Basin. These data support a low-temperature origin of clinoptilolite and contradict the assumption that elevated temperatures are the main controlling factor for authigenic clinoptilolite formation. Increasing clinoptilolite δ18O f values with depth indicate that clinoptilolites which are now in the deeper parts of the zeolite-bearing intervals had either formed at lower temperatures (17-20°C) or under closed system conditions.

  13. The 2017 Plasma Roadmap: Low temperature plasma science and technology

    Science.gov (United States)

    Adamovich, I.; Baalrud, S. D.; Bogaerts, A.; Bruggeman, P. J.; Cappelli, M.; Colombo, V.; Czarnetzki, U.; Ebert, U.; Eden, J. G.; Favia, P.; Graves, D. B.; Hamaguchi, S.; Hieftje, G.; Hori, M.; Kaganovich, I. D.; Kortshagen, U.; Kushner, M. J.; Mason, N. J.; Mazouffre, S.; Mededovic Thagard, S.; Metelmann, H.-R.; Mizuno, A.; Moreau, E.; Murphy, A. B.; Niemira, B. A.; Oehrlein, G. S.; Petrovic, Z. Lj; Pitchford, L. C.; Pu, Y.-K.; Rauf, S.; Sakai, O.; Samukawa, S.; Starikovskaia, S.; Tennyson, J.; Terashima, K.; Turner, M. M.; van de Sanden, M. C. M.; Vardelle, A.

    2017-08-01

    Journal of Physics D: Applied Physics published the first Plasma Roadmap in 2012 consisting of the individual perspectives of 16 leading experts in the various sub-fields of low temperature plasma science and technology. The 2017 Plasma Roadmap is the first update of a planned series of periodic updates of the Plasma Roadmap. The continuously growing interdisciplinary nature of the low temperature plasma field and its equally broad range of applications are making it increasingly difficult to identify major challenges that encompass all of the many sub-fields and applications. This intellectual diversity is ultimately a strength of the field. The current state of the art for the 19 sub-fields addressed in this roadmap demonstrates the enviable track record of the low temperature plasma field in the development of plasmas as an enabling technology for a vast range of technologies that underpin our modern society. At the same time, the many important scientific and technological challenges shared in this roadmap show that the path forward is not only scientifically rich but has the potential to make wide and far reaching contributions to many societal challenges.

  14. Low temperature expansion of the gonihedric Ising model

    CERN Document Server

    Pietig, R

    1998-01-01

    We investigate a model of closed $(d-1)$-dimensional soft-self-avoiding random surfaces on a $d$-dimensional cubic lattice. The energy of a surface configuration is given by $E=J(n_{2}+4k n_{4})$, where $n_{2}$ is the number of edges, where two plaquettes meet at a right angle and $n_{4}$ is the number of edges, where 4 plaquettes meet. This model can be represented as a next-nearest-neighbour- and plaquette-interaction. It corresponds to a special case of a general class of spin systems introduced by Wegner and Savvidy. Since there is no term proportional to the surface area, the bare surface tension of the model vanishes, in contrast to the ordinary Ising model. By a suitable adaption of Peierls argument, we prove the existence of infinitely many ordered low temperature phases for the case $k=0$. A low temperature expansion of the free energy in 3 dimensions up to order $x^{38}$ ($x={e}^{-\\beta J}$) shows, that for $k>0$ only the ferromagnetic low temperature phases remain stable. An analysis of low tempera...

  15. The Low Temperature Microgravity Physics Facility: Progress and Status

    Science.gov (United States)

    Larson, Melora; Pensinger, John; Liu, Feng-Chuan; Dick, G. John

    2003-01-01

    The Jet Propulsion Laboratory (JPL) is developing the Low Temperature Microgravity Physics Facility (LTMPF). The LTMPF is a multiple user and multiple flight facility that will provide a long duration low temperature environment for performing state of the art experiments at the International Space Station (ISS). During each mission, two distinct primary experiments will be accommodated. Secondary experiments utilizing the hardware built for the primary experiments will also be accommodated during each mission. Over the past year, much progress has occurred on the LTMPF as the flight hardware has started to be built. Also, many changes have occurred. Last summer, the initial flight of the LTMPF was delayed until early 2008 by a 2-year slip in the delivery of the Japanese Experiment Module (KIBO) Exposed Facility of the ISS, where the LTMPF will be attached when it flies. Finally, the experiments that will fly as part of the first mission have been changed so that one Gravitational and Relativistic experiment and one Low Temperature Condensed Matter experiment will fly on each flight of the LTMPF. Therefore, the experiments that will fly on the initial mission of the LTMPF will be DYNAMX and the Superconducting Microwave Oscillator Experiment (SUMO).

  16. Formation of silicon oxide grains at low temperature

    CERN Document Server

    Krasnokutski, S A; Jager, C; Huisken, F; Zhukovska, S; Henning, Th

    2013-01-01

    The formation of grains in the interstellar medium, i.e., at low temperature, has been proposed as a possibility to solve the lifetime problem of cosmic dust. This process lacks a firm experimental basis, which is the goal of this study. We have investigated the condensation of SiO molecules at low temperature using neon matrix and helium droplet isolation techniques. The energies of SiO polymerization reactions have been determined experimentally with a calorimetric method and theoretically with calculations based on the density functional theory. The combined experimental and theoretical values have revealed the formation of cyclic (SiO)$_k$ ($k$ = 2--3) clusters inside helium droplets at $T$ = 0.37 K. Therefore, the oligomerization of SiO molecules is found to be barrierless and is expected to be fast in the low-temperature environment of the interstellar medium on the surface of dust grains. The incorporation of numerous SiO molecules in helium droplets leads to the formation of nanoscale amorphous SiO gr...

  17. Application of Low Temperature Detectors in Physics: Yesterday, Today, Tomorrow

    Science.gov (United States)

    Fiorini, Ettore

    2015-06-01

    The main low temperature detectors (LTD) applications and results of LTD in fundamental physics will be considered with particular reference to the nuclear and subnuclear fields. The results obtained with cryogenic techniques and in particularly those with the hybrid ones where bolometers are operated in coincidence or anticoincidence with scintillation or semiconductor detectors will be reported and discussed. In particular the paper will refer to the results and plans in the direct determination of the neutrino mass. In connection with this subject we will review the already obtained and planned results of experiments on neutrinoless double beta decay to reveal the possible violation of the lepton number with the consequent determination or constraint on the neutrino mass. The present and future impact of low temperature techniques in direct detection of Weakly Interacting Massive Particles will be discussed in comparison with the present and future experiments with "classical" detectors. The report will be concluded by the present few and hopefully more numerous future results on the application of low temperature detectors on rare events in low energy nuclear physics.

  18. Low-temperature photoluminescence in self-assembled diphenylalanine microtubes

    Energy Technology Data Exchange (ETDEWEB)

    Nikitin, T. [Institute of Natural Sciences, Ural Federal University, 620000 Ekaterinburg (Russian Federation); Kopyl, S. [Physics Department & CICECO – Materials Institute of Aveiro, University of Aveiro, 3810-193 Aveiro (Portugal); Shur, V.Ya. [Institute of Natural Sciences, Ural Federal University, 620000 Ekaterinburg (Russian Federation); Kopelevich, Y.V., E-mail: kopel@ifi.unicamp.br [Instituto de Fisica, UNICAMP, Campinas, São Paulo 13083-859 (Brazil); Kholkin, A.L., E-mail: kholkin@gmail.com [Institute of Natural Sciences, Ural Federal University, 620000 Ekaterinburg (Russian Federation); Physics Department & CICECO – Materials Institute of Aveiro, University of Aveiro, 3810-193 Aveiro (Portugal)

    2016-04-22

    Bioinspired self-assembled structures are increasingly important for a variety of applications ranging from drug delivery to electronic and energy harvesting devices. An important class of these structures is diphenylalanine microtubes which are potentially important for optical applications including light emitting diodes and optical biomarkers. In this work we present the data on their photoluminescent properties at low temperatures (down to 12 K) and discuss the origin of the emission in the near ultraviolet (UV) range seen earlier in a number of reports. UV luminescence increases with decreasing temperature and exhibits several equidistant lines that are assigned to zero-phonon exciton emission line and its phonon replicas. We infer that the exciton is localized on the defect sites and significant luminescence decay is due to thermal quenching arising from the carrier excitation from these defects and non-radiative recombination. - Highlights: • Low-temperature luminescence is studied in bioinspired self-assembled FF peptide microtubes. • The mechanism of the optical emission is assigned to the luminescence of excitonic states localized at defects. • Luminescence in FF microtubes can be used as an absolute temperature probe at low temperature.

  19. Characterization and performance of Pt/SBA-15 for low-temperature SCR of NO by C3H6.

    Science.gov (United States)

    Liu, Xinyong; Jiang, Zhi; Chen, Mingxia; Shi, Jianwei; Shangguan, Wenfeng; Teraoka, Yasutake

    2013-05-01

    Pt supported on mesoporous silica SBA-15 was investigated as a catalyst for low temperature selective catalytic reduction (SCR) of NO by C3H6 in the presence of excess oxygen. The prepared catalysts were characterized by means of XRD, BET surface area, TEM, NO-TPD, NO/C3H6-TPO, NH3-TPD, XPS and 27Al MAS NMR. The effects of Pt loading amount, O2/C3H6 concentration, and incorporation of Al into SBA-15 have been studied. It was found that the removal efficiency increased significantly after Pt loading, but an optimal loading amount was observed. In particular, under an atmosphere of 150 ppm NO, 150 ppm C3H6, and 18 vol.% O2, 0.5% Pt/SBA-15 showed remarkably high catalytic performance giving 80.1% NOx reduction and 87.04% C3H6 conversion simultaneously at 140 degrees C. The enhanced SCR activity of Pt/SBA-15 is associated with its outstanding oxidation activities of NO to NO2 and C3H6 to CO2 in low temperature range. The research results also suggested that higher concentration of O2 and higher concentration of C3H6 favored NO removal. The incorporation of Al into SBA-15 improved catalytic performance, which could be ascribed to the enhancement of catalyst surface acidity caused by tetrahedrally coordinated AlO4. Moreover, the catalysts could be easily reused and possessed good stability.

  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. Enhanced low-temperature NH3-SCR performance of MnOx/CeO2 catalysts by optimal solvent effect

    Science.gov (United States)

    Yao, Xiaojiang; Kong, Tingting; Chen, Li; Ding, Shimin; Yang, Fumo; Dong, Lin

    2017-10-01

    A series of MnOx/CeO2 catalysts were prepared by modulating the solvents (deionized water (DW), anhydrous ethanol (AE), acetic acid (AA), and oxalic acid (OA) solution) with the purpose of improving the low-temperature NH3-SCR performance, broadening the operating temperature window, and enhancing the H2O + SO2 resistance. The synthesized catalysts were characterized by means of N2-physisorption, XRD, EDS mapping, Raman, XPS, H2-TPR, NH3-TPD, and in situ DRIFTS technologies. Furthermore, the catalytic performance and H2O + SO2 resistance were evaluated by NH3-SCR model reaction. The obtained results indicate that MnOx/CeO2 catalyst prepared with oxalic acid solution as a solvent exhibits the best catalytic performance among these catalysts, which shows above 80% NO conversion during a wide operating temperature range of 100-250 °C and good H2O + SO2 resistance for low-temperature NH3-SCR reaction. This is related to that oxalic acid solution can promote the dispersion of MnOx and enhance the electron interaction between MnOx and CeO2, which are beneficial to improving the physicochemical property of MnOx/CeO2 catalyst, and further lead to the enhancement of catalytic performance and good H2O + SO2 resistance.

  2. Removal of NO(x) at low temperature over mesoporous alpha-Mn2O3 catalyst.

    Science.gov (United States)

    Jeon, Mi-Jin; Park, Sung Hoon; Kim, Ji Man; Jeon, Jong-Ki; Kim, Sang Chai; Kim, Do Heui; Park, Young-Kwon

    2014-03-01

    Low-temperature selective catalytic reduction was carried out over various kinds of manganese oxide (MnOx) catalysts. Mesoporous alpha-Mn2O3, commercial bulk Mn2O3, and Mn/SBA-15 were used as the catalyst. The NOx removal performances of the catalysts were compared. Three different amounts of Mn (5, 10, and 15 wt%) were impregnated on SBA-15 to synthesize Mn/SBA-15. The physical and chemical properties of the catalysts were examined by Brunauer-Emmett-Teller, X-ray diffraction, X-ray photoelectron spectroscopy, and H2-temperature programmed reduction analyses. Of all catalysts examined, mesoporous alpha-Mn2O3 exhibited the highest low-temperature SCR de-NOx efficiency, reaching about 90% at 175 degrees C. This is attributed to strong reducing ability and high oxygen mobility of mesoporous alpha-Mn2O3 and well dispersed Mn2O3 in its mesoporous framework.

  3. Preparation of highly active manganese oxides supported on functionalized MWNTs for low temperature NO{sub x} reduction with NH{sub 3}

    Energy Technology Data Exchange (ETDEWEB)

    Pourkhalil, Mahnaz [Chemical Engineering Faculty, Tarbiat Modares University, P.O. Box 14115-143, Tehran (Iran, Islamic Republic of); Moghaddam, Abdolsamad Zarringhalam, E-mail: zarrin@modares.ac.ir [Chemical Engineering Faculty, Tarbiat Modares University, P.O. Box 14115-143, Tehran (Iran, Islamic Republic of); Rashidi, Alimorad [Nanotechnology Research Center, Research Institute of the Petroleum Industry (RIPI), P.O. Box 18745-4163, Tehran (Iran, Islamic Republic of); Towfighi, Jafar [Chemical Engineering Faculty, Tarbiat Modares University, P.O. Box 14115-143, Tehran (Iran, Islamic Republic of); Mortazavi, Yadollah [Catalysis and Nanostructured Materials Lab, Chemical Engineering Faculty, Tehran University, P.O. Box 11365-4563, Tehran (Iran, Islamic Republic of)

    2013-08-15

    Manganese oxide catalysts (MnO{sub x}) supported on functionalized multi-walled carbon nanotubes (FMWNTs) for low temperature selective catalytic reduction (LTSCR) of nitrogen oxides (NO{sub x}) with NH{sub 3} in the presence of excess O{sub 2} were prepared by the incipient wetness impregnation method. These catalysts were characterized by N{sub 2} adsorption, Fourier transform infrared spectroscopy (FTIR), transmission electron microscope (TEM), X-ray diffraction (XRD), thermal gravimetric analysis (TGA) and H{sub 2}-temperature programmed reduction (H{sub 2}-TPR) methods. The effects of reaction temperature, MnO{sub x} loading, calcination temperature and calcination time were investigated. The presence of surface nitrate species under moderate calcination conditions may play a favorable role in the LTSCR of NO{sub x} with NH{sub 3}. Under the reaction conditions of 200 °C, 1 bar, NO = NH{sub 3} = 900 ppm, O{sub 2} = 5 vol%, GHSV = 30,000 h{sup −1} and 12 wt% MnO{sub x}, NO{sub x} conversion and N{sub 2} selectivity were 97% and 99.5%, respectively. The SCR activity was reduced in the presence of 100 ppm SO{sub 2} and 2.5 vol% H{sub 2}O from 97% to 92% within 6 h at 200 °C, however such an effect was shown to be reversible by exposing the catalyst to a helium flow for 2 h at 350 °C due to thermal decomposition of ammonium sulphate salts.

  4. Low temperature synthesis of Ru–Cu alloy nanoparticles with the compositions in the miscibility gap

    Energy Technology Data Exchange (ETDEWEB)

    Martynova, S.A. [Nicolaev Institute of Inorganic Chemistry SB RAS, Novosibirsk 630090 (Russian Federation); Filatov, E.Yu., E-mail: decan@niic.nsc.ru [Nicolaev Institute of Inorganic Chemistry SB RAS, Novosibirsk 630090 (Russian Federation); Novosibirsk State University, Novosibirsk 630090 (Russian Federation); Korenev, S.V.; Kuratieva, N.V. [Nicolaev Institute of Inorganic Chemistry SB RAS, Novosibirsk 630090 (Russian Federation); Novosibirsk State University, Novosibirsk 630090 (Russian Federation); Sheludyakova, L.A. [Nicolaev Institute of Inorganic Chemistry SB RAS, Novosibirsk 630090 (Russian Federation); Plusnin, P.E.; Shubin, Yu.V. [Nicolaev Institute of Inorganic Chemistry SB RAS, Novosibirsk 630090 (Russian Federation); Novosibirsk State University, Novosibirsk 630090 (Russian Federation); Slavinskaya, E.M. [Boreskov Institute of Catalysis SB RAS, Novosibirsk 630090 (Russian Federation); Boronin, A.I. [Boreskov Institute of Catalysis SB RAS, Novosibirsk 630090 (Russian Federation); Novosibirsk State University, Novosibirsk 630090 (Russian Federation)

    2014-04-01

    A complex salt [Ru(NH{sub 3}){sub 5}Cl][Cu(C{sub 2}O{sub 4}){sub 2}H{sub 2}O]—the precursor of nanoalloys combining ruthenium and copper was prepared. It crystallizes in the monoclinic space group P2{sub 1}/n. Thermal properties of the prepared salt were examined in different atmospheres (helium, hydrogen, oxygen). Thermal decomposition of the precursor in inert atmosphere was thoroughly examined and the intermediate products were characterized. Experimental conditions for preparation of copper-rich (up to 12 at% of copper) metastable solid solution Cu{sub x}Ru{sub 1−x} (based on Ru structure) were optimized, what is in sharp contrast to the bimetallic miscibility gap known for the bulk counterparts in a wide composition range. Catalytic properties of copper–ruthenium oxide composite were tested in catalytic oxidation of CO. - Highlights: • We synthesized new precursor of CuRu metastable nanoalloys. • Thermal properties of the prepared salt were examined in different atmospheres. • Thermodestruction mechanism of precursor are studied. • Cu{sub 0.12}Ru{sub 0.88} nanoalloy with the compositions in the miscibility gap is obtained. • Catalytic conversion of CO on copper–ruthenium oxide composite were examined.

  5. Catalytic Effect of NdCoO_3 Nanoparticles on the Thermal Decomposition of Ammonium Perchlorate by DSC/TG-MS%纳米NdCoO_3催化高氯酸铵热分解的DSC/TG-MS研究

    Institute of Scientific and Technical Information of China (English)

    余宗学; 江晓红; 陆路德; 汪信

    2009-01-01

    Cubic structural perovskite NdCoO_3 nanocrystals were prepared by microemulsion method. The catalytic effect of the NdCoO_3 for thermal decomposition of ammonium perchlorate (AP) was investigated by DSC and TG-MS. The results revealed that the NdCoO_3 nanoparticles had effective catalysis on the thermal decomposition of AP. Adding 2% of NdCoO_3 nanoparticles to AP decreased the temperature of thermal decomposition by 113 ℃ and increased the heat of decomposition from 655 J·g~(-1) to 1 363 J·g~(-1). Gaseous products of thermal decomposition of AP were NH_3, H_2O, O_2, HCl, N_2O, NO, NO_2 and Cl_2. The mechanism of catalytic action was based on the presence of superoxide ion (O_2~-) and oxygenic ion (O~-, O~(2-)) on the surface of NdCoO_3, and the difference of thermal decomposition of AP with 2% of NdCoO_3 and pure AP was mainly caused by the different extent of oxidation of ammonium.%采用微乳液法制备了立方晶系的NdCoO_3纳米晶.利用DSC/TG-MS研究了NdCoO_3对AP热分解的催化作用.结果表明,在NdCoO_3的催化作用下,AP的热分解反应峰值温度下降了113℃,表观分解反应热从655 J·g~(-1)增加到1 363 J·g~(-1),分解的气相产物主要有NH3,H_2O,O_2,HCl,N_2O,NO,NO_2和Cl_2.在金属氧化物表面吸附生成超氧化离子(O_2~-)和氧离子(O~-,O~(2-)),这是加速AP分解反应的主要原因.加入NdCoO_3催化AP热分解,由于对氨的氧化深度不同而导致分解放热量的增加.

  6. Development of a stabilized low temperature infrared absorption cell for use in low temperature and collisional cooling experiments.

    Science.gov (United States)

    Valentin, A; Henry, A; Claveau, C; Camy-Peyret, C; Hurtmans, D; Mantz, A W

    2004-12-01

    We have constructed a stabilized low temperature infrared absorption cell cooled by an open cycle refrigerator, which can run with liquid nitrogen from 250 to 80K or with liquid helium from 80K to a few kelvin. Several CO infrared spectra were recorded at low temperature using a tunable diode laser spectrometer. These spectra were analyzed taking into account the detailed effects of collisions on the line profile when the pressure increases. We also recorded spectra at very low pressure to accurately model the diode laser emission. Spectra of the R(2) line in the fundamental band of 13CO cooled by collisions with helium buffer gas at 10.5K and at pressures near 1 Torr have been recorded. The He-pressure broadening parameter (gamma(0) = 0.3 cm(-1) atm(-1)) has been derived from the simultaneous analysis of four spectra at different pressures.

  7. Electrochemical decomposition of chlorinated hydrocarbons

    OpenAIRE

    McGee, Gerard Anthony

    1993-01-01

    This work involves the characterisation of the electrochemical decomposition of chlorinated hydrocarbons. A variety of methods were employed involving the use of catalytic reagents to enhance the rate at which chlorinated organic compounds are reduced. The first reagent used was oxygen which was electrochemically reduced to superoxide in nonaqueous solvents. Superoxide is a reactive intermediate and decomposes chlorinated hydrocarbons. However it was found that since the rate of reaction betw...

  8. Erosion–corrosion and corrosion properties of DLC coated low temperature Erosion–corrosion and corrosion properties of DLC coated low temperature

    DEFF Research Database (Denmark)

    Jellesen, Morten Stendahl; Christiansen, Thomas; Hilbert, Lisbeth Rischel

    2009-01-01

    of AISI 316 as substrate for DLC coatings are investigated. Corrosion and erosion–corrosion measurements were carried out on low temperature nitrided stainless steel AISI 316 and on low temperature nitrided stainless steel AISI 316 with a top layer of DLC. The combination of DLC and low temperature...

  9. 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

  10. 1992--1993 low-temperature geothermal assessment program, Colorada

    Energy Technology Data Exchange (ETDEWEB)

    Cappa, J.A.; Hemborg, H.T.

    1995-01-01

    Previous assessments of Colorado`s low-temperature geothermal resources were completed by the Colorado Geological Survey in 1920 and in the mid- to late-1970s. The purpose of the 1992--1993 low-temperature geothermal resource assessment is to update the earlier physical, geochemical, and utilization data and compile computerized databases of the location, chemistry, and general information of the low-temperature geothermal resources in Colorado. The main sources of the data included published data from the Colorado Geological Survey, the US Geological Survey WATSTOR database, and the files of the State Division of Water Resources. The staff of the Colorado Geological Survey in 1992 and 1993 visited most of the known geothermal sources that were recorded as having temperatures greater than 30{degrees}C. Physical measurements of the conductivity, pH, temperature, flow rate, and notes on the current geothermal source utilization were taken. Ten new geochemical analyses were completed on selected geothermal sites. The results of the compilation and field investigations are compiled into the four enclosed Quattro Pro 4 databases. For the purposes of this report a geothermal area is defined as a broad area, usually less than 3 sq mi in size, that may have several wells or springs. A geothermal site is an individual well or spring within a geothermal area. The 1992-1993 assessment reports that there are 93 geothermal areas in the Colorado, up from the 56 reported in 1978; there are 157 geothermal sites up from the 125 reported in 1978; and a total of 382 geochemical analyses are compiled, up from the 236 reported in 1978. Six geothermal areas are recommended for further investigation: Trimble Hot Springs, Orvis Hot Springs, an area southeast of Pagosa Springs, the eastern San Luis Valley, Rico and Dunton area, and Cottonwood Hot Springs.

  11. Alternating current calorimetry at very high pressure and low temperature

    CERN Document Server

    Wilhelm, H

    2002-01-01

    The specific heat of CePd sub 2 sub . sub 0 sub 2 Ge sub 1 sub . sub 9 sub 8 has been measured with an ac calorimetric technique up to 22 GPa for temperatures in the range 0.3 K <=T <=10 K. A thermocouple allowed the temperature oscillations to be read when an ac heating current was sent through the sample. The inverse of the thermovoltage V sub a sub c recorded at low temperature exhibits a pronounced anomaly as a function of pressure. It is shown that 1/V sub a sub c extrapolated to zero temperature is a measure of the Sommerfeld coefficient gamma.

  12. A Low Temperature Analysis of the Boundary Driven Kawasaki Process

    Science.gov (United States)

    Maes, Christian; O'Kelly de Galway, Winny

    2013-12-01

    Low temperature analysis of nonequilibrium systems requires finding the states with the longest lifetime and that are most accessible from other states. We determine these dominant states for a one-dimensional diffusive lattice gas subject to exclusion and with nearest neighbor interaction. They do not correspond to lowest energy configurations even though the particle current tends to zero as the temperature reaches zero. That is because the dynamical activity that sets the effective time scale, also goes to zero with temperature. The result is a non-trivial asymptotic phase diagram, which crucially depends on the interaction coupling and the relative chemical potentials of the reservoirs.

  13. New insights in the low-temperature oxidation of acetylene

    DEFF Research Database (Denmark)

    Wang, Bing-Yin; Liu, Yue-Xi; Weng, Jun-Jie

    2017-01-01

    This work presents new experimental data of C2H2 low-temperature oxidation for equivalence ratios Φ= 0.5–3.0 in a newly designed jet-stirred reactor over a temperature range of 600–1100K at atmospheric pressure with residence time corresponding from 1.94 to 1.06s. Mole fraction profiles of 17 int...... formation at temperatures above 1000K. In addition to the present data, the model predicts well ignition delay times reported in literature....

  14. Two loop low temperature corrections to electron self energy

    Institute of Scientific and Technical Information of China (English)

    Mahnaz Q. Haseeb; Samina S. Masood

    2011-01-01

    We xecalculate the two loop corrections in the background heat bath using real time formalism.The procedure of the integrations of loop momenta with dependence on finite temperature before the moments without it has been followed. We determine the mass and wavefunction renormalization constants in the low temperature limit of QED, for the first time with this preferred order of integrations. The correction to electron mass and spinors in this limit is important in the early universe at the time of primordial nucleosynthesis as well as in astrophysics.

  15. Ionic Conduction in Cubic Zirconias at Low Temperatures

    Institute of Scientific and Technical Information of China (English)

    Ying LI; Yunfa CHEN; Jianghong GONG

    2004-01-01

    The ac conductivities of Y2O3 or CaO-stabilized cubic zirconias were obtained from complex impedance measurements in the temperature range from 373 to 473 K. By analyzing the temperature-dependence of the resultant dc conductivities, it was shown that the activation energies for conduction are lower than those reported previously for the same materials at high temperatures. Comparing the activation energy data with the theoretically estimated values revealed that there may exist a certain, although very small, amount of free oxygen vacancies in the test samples at low temperatures and the conduction in the test samples is a result of the migration of these free oxygen vacancies.

  16. Complex-compound low-temperature TES system

    Energy Technology Data Exchange (ETDEWEB)

    Rockenfeller, U. [Rocky Research, Boulder City, NV (United States)

    1989-03-01

    Development of a complex-compound low-temperature TES system is described herein from basic chemical principles through current bench scale system development. Important application engineering issues and an economic outlook are addressed as well. The system described uses adsorption reactions between solid metal inorganic salts and ammonia refrigerant. It is the coordinative nature of these reactions that allows for storage of ammonia refrigerant within the solid salt crystals that function as a chemical compressor during on peak periods (substituting the mechanical compressor) and release ammonia during off peak periods while a mechanical vapor compression system provides the necessary reactor pressure and heat.

  17. Low temperature properties of some Er-rich intermetallic compounds

    Energy Technology Data Exchange (ETDEWEB)

    K.A. Gshneidner,jr; A.O. Pecharsky; L.Hale; V.K. Pecharsky

    2004-09-30

    The low temperature volumetric heat capacity ({approx}3.5 to 350 K) and magnetic susceptibility ({approx}4 to 320 K) of Er{sub 3}Rh, Er{sub 3}Ir, Er{sub 3}Pt, Er{sub 2}Al, and Er{sub 2}Sn have been measured. All of the compounds order antiferromagnetically (or ferrimagnetically), and most exhibit more than one magnetic ordering transition. The volumetric heat capacities in general are smaller than those of the prototype magnetic regenerator materials, except for Er{sub 3}Ir in the 12 to 14 K temperature range.

  18. High-pressure-low-temperature x-ray power diffractometer.

    Science.gov (United States)

    Syassen, K; Holzapfel, W B

    1978-08-01

    A high-pressure technique for x-ray diffraction studies at low temperatures is described. The system consists of a Bridgman anvil type high-pressure device with either tungsten carbide or boron carbide anvils, a liquid He cryostat, and x-ray diffractometer operating in Debye-Scherrer geometry. The newly developed boron carbide anvil cell is capable of containing a liquid pressure transmitting medium. The precision of the lattice parameter determination is discussed and the effect of nonisostatic stress components on the diffraction pattern is examined.

  19. Low Temperature Microgravity Physics Facility Payload for the ISS

    Science.gov (United States)

    Langford, Don; Pensinger, John

    2003-01-01

    The LTMPF Payload is a 182-liter superfluid-helium dewar that will be attached to the JEM-EF facility of the International Space Station after launch in the cargo bay of the Space Shuttle. The LTMPF Payload will provide a major low-temperature research laboratory for Fundamental Physics experiments on the International Space Station. The LTMPF payload will provide instrument temperatures below superfluid helium temperatures and the ISS will provide microgravity to allow the experiments to study condensed matter and gravitational physics. Each flight will be allocated to one condensed matter instrument and one gravitation instrument.

  20. 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).