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Sample records for catalytic ammonia decomposition

  1. 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...

  2. 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.

  3. Ammonia Decomposition for Hydrogen Production in Catalytic Microchannels with Slip/Jump Effects

    Directory of Open Access Journals (Sweden)

    Azad Qazi Zade

    2015-01-01

    Full Text Available The rarefaction effects on the catalytic decomposition of NH3 in ruthenium–coated planar microchannels is numerically simulated in the Knudsen number range 0.015-0.03. A colocated finite–volume method is used to solve the governing equations. A concentration jump model derived from the kinetic theory of gases is employed to account for the concentration discontinuity at the reactive walls. A detailed surface reaction mechanism for ammonia decomposition on ruthenium along with a multi-component species diffusion model are used to study the effects of concentration jump coupled with velocity slip and temperature jump on the walls. The velocity-slip, temperature-jump and concentration-jump boundary conditions have miscellaneous effects on flow, temperature and species concentration fields. The results suggest that the velocity-slip boundary condition only slightly influences the species distribution at the edge of the Knudsen layer as well as inside the channel, while the temperature-jump boundary condition affects the heat and mass transfer characteristics the most. The concentration-jump effect, on the other hand, can counter balance the temperature-jump effects in some cases.

  4. 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.

  5. Catalytic ammonia oxidation to nitrogen (I) oxide

    OpenAIRE

    MASALITINA NATALIYA YUREVNA; SAVENKOV ANATOLIY SERGEEVICH

    2015-01-01

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

  6. Effect of H{sub 2}S on the catalytic decomposition of tar and ammonia with dolomite and sintered iron ore in synthetic gasification gas

    Energy Technology Data Exchange (ETDEWEB)

    Hepola, J. [VTT Energy, Espoo (Finland)

    1996-12-31

    The toluene-decomposing activity of calcined dolomite was not affected by the H{sub 2}S content of synthetic gasification gas. Iron was active with respect to toluene and ammonia at metallic state. The increase of the H{sub 2}S content of synthetic gasification gas (0 - 500 ppmv) decreased the tar-decomposing activity but not the ammonia- decomposing activity of sintered iron ore. (author) (12 refs.)

  7. Selective catalytic oxidation of ammonia

    Energy Technology Data Exchange (ETDEWEB)

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

    1996-12-31

    In the combustion of fossil fuels, the principal source of nitrogen oxides is nitrogen bound in the fuel structure. In gasification, a large part of fuel nitrogen forms NH{sub 3}, which may form nitrogen oxides during gas combustion. If NH{sub 3} and other nitrogen species could be removed from hot gas, the NO emission could be considerably reduced. However, relatively little attention has been paid to finding new means of removing nitrogen compounds from the hot gasification gas. The possibility of selectively oxidizing NH{sub 3} to N{sub 2} in the hot gasification has been studied at VTT Energy. The largest NH{sub 3} reductions have been achieved by catalytic oxidation on aluminium oxides. (author) (4 refs.)

  8. Decomposition of indoor ammonia with TiO 2-loaded cotton woven fabrics prepared by different textile finishing methods

    Science.gov (United States)

    Dong, Yongchun; Bai, Zhipeng; Liu, Ruihua; Zhu, Tan

    Addition of urea-based antifreeze admixtures during cement mixing in construction of buildings has led to increasing indoor air pollution due to continuous transformation and emission of urea to gaseous ammonia in indoor concrete wall. In order to control ammonia pollution from indoor concrete wall, the aqueous dispersion was firstly prepared with nano-scale TiO 2 photocatalysts and dispersing agent, and then mixed with some textile additives to establish a treating bath or coating paste. Cotton woven fabrics were used as the support materials owing to their large surface area and large number of hydrophilic groups on their cellulose molecules and finished using padding and coating methods, respectively. Two TiO 2-loaded fabrics were obtained and characterized by X-ray diffractometer (XRD) and scanning electron microscopy (SEM). Moreover, a specifically designed ammonia photocatalytic system consisting of a small environmental chamber and a reactor was used for assessing the performance of these TiO 2-loaded fabrics as the wall cloth or curtains used in house rooms in the future and some factors affecting ammonia decomposition are discussed. Furthermore, a design equation of surface catalytic kinetics was developed for describing the decomposition of ammonia in air stream. The results indicated that increasing dosage of the TiO 2 aqueous dispersion in treating bath or coating paste improved the ammonia decomposition. And ammonia was effectively removed at low ammonia concentration or gas flow rate. When relative humidity level was 45%, ammonia decomposition was remarkably enhanced. It is the fact that ammonia could be significantly decomposed in the presence of the TiO 2-padded cotton fabric. Whereas, the TiO 2-coated cotton fabric had the reduced photocatalytic decomposition of ammonia and high adsorption to ammonia owing to their acrylic binder layer. Finally, the reaction rate constant k and the adsorption equilibrium constant K values were determined through a

  9. Catalytic Decomposition of Methylene Chloride by Sulfated Titania Catalysts

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    Catalytic decomposition of methylene chloride in air below 300℃ was studied.Sulfated titania was very effective in converting 959ppm methylene chloride selectively to CO,CO2 and HCl.Complete decomposition of methylene chloride was achieved at low temperature(275℃).It was found that the acidic property of catalyst was a determinant factor for the catalytic activity.The presence of water vapor in the feed stream remarkably reduced the catalytic activity,which could be due to the blockage of acidic sites on the surface of catalyst by water molecules.A bifunctional catalyst comprising copper oxide was developed to improve the selectivity of catalytic oxidation,which indicated that copper oxide can promote the deep oxidation of methylene chloride.The crystal form of TiO2 imposes an important influence upon the catalytic oxidation.

  10. 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....

  11. Ammonia Decomposition with Manganese Nitride-Calcium Imide Composites as Efficient Catalysts.

    Science.gov (United States)

    Yu, Pei; Guo, Jianping; Liu, Lin; Wang, Peikun; Wu, Guotao; Chang, Fei; Chen, Ping

    2016-02-19

    Ammonia has high gravimetric and volumetric hydrogen densities and is, therefore, considered a promising carrier for the production of COx -free molecular H2 for forthcoming energy systems. Alkaline earth metals are generally regarded as structural promoters of catalysts and employed in numerous catalytic processes. Here, we report that calcium imide (CaNH) has a strong synergistic effect on Mn6 N5 in catalyzing the decomposition of NH3 , leading to a ca. 40 % drop in apparent activation energy. At 773 K, the H2 formation rate over a Mn6 N5 -11CaNH composite catalyst is about an order of magnitude higher than that of Mn6 N5 and comparable to the highly active Ni/SBA-15 and Ru/Al2 O3 catalysts. Analysis by means of temperature-programmed decomposition (TPD), X-ray diffraction (XRD), and X-ray absorption near edge spectroscopy (XANES) reveal that CaNH participates in the catalysis via forming a [Ca6 MnN5 ]-like intermediate, thus altering the reaction pathway and energetics. A two-step catalytic cycle, accounting for the synergy between CaNH and Mn6 N5 , is proposed. PMID:26914173

  12. Assessing the reliability of calculated catalytic ammonia synthesis rates

    DEFF Research Database (Denmark)

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

    2014-01-01

    We introduce a general method for estimating the uncertainty in calculated materials properties based on density functional theory calculations. We illustrate the approach for a calculation of the catalytic rate of ammonia synthesis over a range of transition-metal catalysts. The correlation...... between errors in density functional theory calculations is shown to play an important role in reducing the predicted error on calculated rates. Uncertainties depend strongly on reaction conditions and catalyst material, and the relative rates between different catalysts are considerably better described...

  13. Ammonia Decomposition over Bimetallic Nitrides Supported on γ-Al2O3

    Institute of Scientific and Technical Information of China (English)

    Chun Shan LU; Xiao Nian LI; Yi Feng ZHU; Hua Zhang LIU; Chun Hui ZHOU

    2004-01-01

    A series of monometallic nitrides and bimetallic nitrides were prepared by temperature-programmed reaction with NH3. The effects of Co, Ni and Fe additives and the synergic action between Fe, Co, Ni and Mo on the ammonia decomposition activity were investigated. TPR-MS, XRD were also carried out to obtain better insight into the structure of the bimetallic nitride. The results of ammonia decomposition activity show that bimetallic nitrides are more active than monometallic nitrides or bimetallic oxides.

  14. 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.

  15. 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.

  16. Ammonia synthesis and decomposition on a Ru-based catalyst modeled by first-principles

    DEFF Research Database (Denmark)

    Hellman, A.; Honkala, Johanna Karoliina; Remediakis, Ioannis;

    2009-01-01

    ) that small changes in the relative adsorption potential energies are sufficient to get a quantitative agreement between theory and experiment (Appendix A) and (ii) that it is possible to reproduce results from the first-principles model by a simple micro-kinetic model (Appendix B).......A recently published first-principles model for the ammonia synthesis on an unpromoted Ru-based catalyst is extended to also describe ammonia decomposition. In addition, further analysis concerning trends in ammonia productivity, surface conditions during the reaction, and macro......-properties, such as apparent activation energies and reaction orders are provided. All observed trends in activity are captured by the model and the absolute value of ammonia synthesis/decomposition productivity is predicted to within a factor of 1-100 depending on the experimental conditions. Moreover it is shown: (i...

  17. Monnte Carlo Simulation of Kinetics of Ammonia Oxidative Decomposition over the Commercial Propylene Ammoxidation Catalyst(Mo-Bi)

    Institute of Scientific and Technical Information of China (English)

    罗正鸿; 詹晓力; 等

    2003-01-01

    Monte Carlo method is applied to investigate the kinetics of ammonia oxidative decomposition over the commercial propylene ammoxidation catalyst(Mo-Bi).The simulation is quite in agreement with experimetal results.Monte Carlo simulation proves that the process of ammonia oxidation decomposition is a two-step reaction.

  18. Characterization of FeCo based catalyst for ammonia decomposition. The effect of potassium oxide

    Directory of Open Access Journals (Sweden)

    Lendzion-Bieluń Zofia

    2014-12-01

    Full Text Available FeCo fused catalyst was obtained by fusing iron and cobalt oxides with an addition of calcium, aluminium, and potassium oxides (CaO, Al2O3, K2O. An additional amount of potassium oxide was inserted by wet impregnation. Chemical composition of the prepared catalysts was determined with an aid of the XRF method. On the basis of XRD analysis it was found that cobalt was built into the structure of magnetite and solid solution of CoFe2O4 was formed. An increase in potassium content develops surface area of the reduced form of the catalyst, number of adsorption sites for hydrogen, and the ammonia decomposition rate. The nitriding process of the catalyst slows down the ammonia decomposition.

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

    Science.gov (United States)

    Wu, Daishe; Deng, Haiwen; Wang, Wuyi; Xiao, Huayun

    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 microg g(-1) and 0.29 microg g(-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. PMID:17920390

  1. Impact of selective catalytic reduction on exhaust particle formation over excess ammonia events.

    Science.gov (United States)

    Amanatidis, Stavros; Ntziachristos, Leonidas; Giechaskiel, Barouch; Bergmann, Alexander; Samaras, Zissis

    2014-10-01

    The introduction of selective catalytic reduction (SCR) aftertreatment to meet stringent diesel NOx emission standards around the world increases exhaust ammonia. Further to the direct air quality and health implications of ammonia, this may also lead to particle formation in the exhaust. In this study, an ammonia SCR system was examined with respect to its impact on both solid and total exhaust particle number and size distribution, downstream of a diesel particulate filter (DPF). Fuel post-injection was conducted in some tests to investigate the effect of ammonia during active DPF regeneration. On average, the post-DPF solid >23 nm and total <23 nm particle number emissions were increased by 129% (range 80-193%) and by 67% (range 26-136%), respectively, when 100 ppm ammonia level was induced downstream of the SCR catalyst. This is a typical level during ammonia overdosing, often practiced for efficient NOx control. Ammonia did not have a significant additional effect on the high particle concentrations measured during DPF regeneration. Based on species availability and formation conditions, sulfate, nitrate, and chloride salts with ammonium are possible sources of the new particles formed. Ammonia-induced particle formation corresponds to an environmental problem which is not adequately addressed by current regulations.

  2. Chemical deactivation of Cu-SSZ-13 ammonia selective catalytic reduction (NH3-SCR) systems

    NARCIS (Netherlands)

    Lezcano-Gonzalez, I.; Deka, U.; van der Bij, H. E.; Paalanen, P.; Arstad, B.; Weckhuysen, B. M.; Beale, A. M.

    2014-01-01

    The chemical deactivation of Cu-SSZ-13 Ammonia Selective Catalytic Reduction (NH3-SCR) catalysts by Pt, Zn, Ca and P has been systematically investigated using a range of analytical techniques in order to study the influence on both the zeolitic framework and the active Cu2+ ions. The results obtain

  3. Study on the Carbon-Methanation and Catalytic Activity of Ru/AC for Ammonia Synthesis

    Institute of Scientific and Technical Information of China (English)

    祝一锋; 李小年; 季德春; 刘化章

    2004-01-01

    The effects of promoters K, Ba, Sm on the resistance to carbon-methanation and catalytic activity of ruthenium supported on active carbon (Ru/AC) for ammonia synthesis have been studied by means of TG-DTG (thermalgravity-differential thermalgravity), temperature-programmed desorption, and activity test. Promoters Ba,K, and Sm increased the activity of Ru/AC catalysts for ammonia synthesis significantly. Much higher activity can be reached for Ru/AC catalyst with bi- or tri-promoters. Indeed, the triply promoted catalyst showed the highest activity, coupled to a surprisingly high resistance to methanation. The ability of resistance of promoter to methanation of Ru/AC catalyst is dependent on the adsorption intensity of hydrogen. The strong adsorption of hydrogen would enhance methanation and impact the adsorption of nitrogen, which results in the decrease of catalytic activity.

  4. Kinetics Study of the Effect of Oxygen on Ammonia Decomposition on Ru%Ru上有氧条件下氨分解的动力学研究

    Institute of Scientific and Technical Information of China (English)

    李忠来; 梁长海; 王德峥; 李灿

    2004-01-01

    @@ It has been shown that Ru is valid for the synthesis and decomposition of ammonia[1,2]. Further study of ammonia adsorption and its decomposition products desorption on Ru will be important. Previous studies of ammonia adsorption on Ru mainly focused on the ammonia synthesis and hydrogen production in the absence of oxygen[3], only a few investigations on ammonia decomposition in the presence of oxygen have been reported[4,5], and the effect of adsorbed oxygen on the rates of ammonia decomposition and product formation on Ru are still not well understood. In this paper, NH3 decomposition on Ru/SiO2 was investigated in the presence of oxygen using a temporal analysis of products (TAP) reactor.

  5. 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.

  6. Macrophyte decomposition in a surface-flow ammonia-dominated constructed wetland: Rates associated with environmental and biotic variables

    Science.gov (United States)

    Thullen, J.S.; Nelson, S.M.; Cade, B.S.; Sartoris, J.J.

    2008-01-01

    Decomposition of senesced culm material of two bulrush species was studied in a surface-flow ammonia-dominated treatment wetland in southern California. Decomposition of the submerged culm material during summer months was relatively rapid (k = 0.037 day-1), but slowed under extended submergence (up to 245 days) and during fall and spring sampling periods (k = 0.009-0.014 day-1). Stepwise regression of seasonal data indicated that final water temperature and abundance of the culm-mining midge, Glyptotendipes, were significantly associated with culm decomposition. Glyptotendipes abundance, in turn, was correlated with water quality parameters such as conductivity and dissolved oxygen and ammonia concentrations. No differences were detected in decomposition rates between the bulrush species, Schoenoplectus californicus and Schoenoplectus acutus.

  7. Demonstration of the Catalytic Decomposition of Hydrogen Peroxide.

    Science.gov (United States)

    Conklin, Alfred R. Jr.; Kessinger, Angela

    1996-01-01

    Describes a demonstration known as Elephant's Toothpaste in which the decomposition of hydrogen peroxide is catalyzed by iodide. Oxygen is released and soap bubbles are produced. The foam produced is measured, and results show a good relationship between the amount of foam and the concentration of the hydrogen peroxide. (DDR)

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

    Institute of Scientific and Technical Information of China (English)

    Virginie Fontanier; Sofiane Zalouk; Stéphane Barbati

    2011-01-01

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

  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. Electrochemical and catalytic properties of Ni/BaCe0.75Y0.25O3-δ anode for direct ammonia-fueled solid oxide fuel cells.

    Science.gov (United States)

    Yang, Jun; Molouk, Ahmed Fathi Salem; Okanishi, Takeou; Muroyama, Hiroki; Matsui, Toshiaki; Eguchi, Koichi

    2015-04-01

    In this study, Ni/BaCe0.75Y0.25O3-δ (Ni/BCY25) was investigated as an anode for direct ammonia-fueled solid oxide fuel cells. The catalytic activity of Ni/BCY25 for ammonia decomposition was found to be remarkably higher than Ni/8 mol % Y2O3-ZrO2 and Ni/Ce0.90Gd0.10O1.95. The poisoning effect of water and hydrogen on ammonia decomposition reaction over Ni/BCY25 was evaluated. In addition, an electrolyte-supported SOFC employing BaCe0.90Y0.10O3-δ (BCY10) electrolyte and Ni/BCY25 anode was fabricated, and its electrochemical performance was investigated at 550-650 °C with supply of ammonia and hydrogen fuel gases. The effect of water content in anode gas on the cell performance was also studied. Based on these results, it was concluded that Ni/BCY25 was a promising anode for direct ammonia-fueled SOFCs. An anode-supported single cell denoted as Ni/BCY25|BCY10|Sm0.5Sr0.5CoO3-δ was also fabricated, and maximum powder density of 216 and 165 mW cm(-2) was achieved at 650 and 600 °C, for ammonia fuel, respectively.

  12. Catalytic Decomposition of Toluene Using Various Dielectric Barrier Discharge Reactors

    Institute of Scientific and Technical Information of China (English)

    YE Daiqi; HUANG Haibao; CHEN Weili; ZENG Ronghui

    2008-01-01

    Decomposition of toluene was experimentally investigated with various dielectric barrier discharge (DBD) reactors, such as wire-cylinder, wire-plate and plate-to-plate, combined with multi-metal oxides catalyst (Mn-Ni-Co-Cu-Ox/Al2O3) loaded on the cordierite honeycomb and nickel foam, respectively. The effects of some factors including the residence time, reactor configuration and catalyst, upon the toluene destruction were studied. Results revealed that the use of in-plasma catalysis was more helpful to enhancing the DRE (destruction and removal efficiency) and reducing the O3 formation than that of either post-plasma catalysis or plasma alone. It was demonstrated that the wire-plate reactor was favorable for the oxidation reaction of toluene and the nickel foam-supported catalysts exhibited good activity.

  13. INVESTIGATION OF AMMONIA ADSORPTION ON FLY ASH DUE TO INSTALLATION OF SELECTIVE CATALYTIC REDUCTION SYSTEMS

    Energy Technology Data Exchange (ETDEWEB)

    G.F. Brendel; J.E. Bonetti; R.F. Rathbone; R.N. Frey Jr.

    2000-11-01

    This report summarizes an investigation of the potential impacts associated with the utilization of selective catalytic reduction (SCR) systems at coal-fired power plants. The study was sponsored by the U.S. Department of Energy Emission Control By-Products Consortium, Dominion Generation, the University of Kentucky Center for Applied Energy Research and GAI Consultants, Inc. SCR systems are effective in reducing nitrogen oxides (NOx) emissions as required by the Clean Air Act (CAA) Amendments. However, there may be potential consequences associated with ammonia contamination of stack emissions and combustion by-products from these systems. Costs for air quality, landfill and pond environmental compliance may increase significantly and the marketability of ash may be seriously reduced, which, in turn, may also lead to increased disposal costs. The potential impacts to air, surface water, groundwater, ash disposal, ash utilization, health and safety, and environmental compliance can not be easily quantified based on the information presently available. The investigation included: (1) a review of information and data available from published and unpublished sources; (2) baseline ash characterization testing of ash samples produced from several central Appalachian high-volatile bituminous coals from plants that do not currently employ SCR systems in order to characterize the ash prior to ammonia exposure; (3) an investigation of ammonia release from fly ash, including leaching and thermal studies; and (4) an evaluation of the potential impacts on plant equipment, air quality, water quality, ash disposal operations, and ash marketing.

  14. 双分子水和氨气催化CF3OH分子裂解的理论研究%Theoretical Study on Decomposition of CF3OH Catalyzed by Water Dimer and Ammonia

    Institute of Scientific and Technical Information of China (English)

    龙波; 谭兴凤; 隆正文; 任达森; 张为俊

    2011-01-01

    The G3 and CBS-QB3 theoretical methods are employed to study the decomposition of CF3OH into FCFO and HF by water, water dimmer, and ammonia. The decomposition of CF3OH into FCFO and HF is unlikely to occur in the atmosphere due to the high activated energy of 88.7 k J/mol at the G3 level of theory. However, the computed results predict that the barrier for unimolecular decomposition of CF3OH is decreased to 25.1 k J/mol from 188.7 k J/mol with the aid of NH3 at the G3 level of theory, which shows that the ammonia play a strong catalytic effect on the split of CF3OH. In addition, the calculated rate constants show that the decomposition of CF3OH by NH3 is faster than those of H2Oand the water dimmer by 109 and 105 times respectively. The rate constants combined with the corresponding concentrations of these species demonstrate that the reaction CF3 OH with NH3 via TS4 is of great importance for the decomposition of CF3OH in the atmosphere.

  15. 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.

  16. H2 production by catalytic methane decomposition on Cu based catalyst

    International Nuclear Information System (INIS)

    The thermo-catalytic decomposition (TCD) of methane has been investigated in a laboratory scale fixed bed reactor using a copper dispersed on γ-alumina as a catalyst. The usefulness of a fluidized bed operation instead of a fixed bed one has been assessed in terms of methane to hydrogen conversion, amount of carbon accumulated on the catalyst, possibility of the catalyst regeneration. The results highlight some promising features in using fluidized bed reactors in the TCD process. (authors)

  17. Ammonia for hydrogen storage: challenges and opportunities

    DEFF Research Database (Denmark)

    Klerke, Asbjørn; Christensen, Claus H.; Nørskov, Jens Kehlet;

    2008-01-01

    The possibility of using ammonia as a hydrogen carrier is discussed. Compared to other hydrogen storage materials, ammonia has the advantages of a high hydrogen density, a well-developed technology for synthesis and distribution, and easy catalytic decomposition. Compared to hydrocarbons...... and alcohols, it has the advantage that there is no CO2 emission at the end user. The drawbacks are mainly the toxicity of liquid ammonia and the problems related to trace amounts of ammonia in the hydrogen after decomposition. Storage of ammonia in metal ammine salts is discussed, and it is shown...... that this maintains the high volumetric hydrogen density while alleviating the problems of handling the ammonia. Some of the remaining challenges for research in ammonia as a hydrogen carrier are outlined....

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

    OpenAIRE

    Irene Lock Sow Mei; S.S.M. Lock; Dai-Viet N. Vo; Bawadi Abdullah

    2016-01-01

    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 u...

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

    NARCIS (Netherlands)

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

    2014-01-01

    Three different types of NH3 species can be simultaneously present on Cu(2+)-exchanged CHA-type zeolites, commonly used in Ammonia Selective Catalytic Reduction (NH3-SCR) systems. These include ammonium ions (NH4(+)), formed on the Brønsted acid sites, [Cu(NH3)4](2+) complexes, resulting from NH3 co

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

    Energy Technology Data Exchange (ETDEWEB)

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

    1999-12-10

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

  1. Catalytic on-board hydrogen production from methanol and ammonia for mobile application

    Energy Technology Data Exchange (ETDEWEB)

    Soerijanto, H.

    2008-08-15

    unfavourable for energetic and economic reasons, it is reasonable to investigate another reaction system, which is free of carbon. At the last part of this study the catalytic production of hydrogen from ammonia cracking was investigated. Ammonia is an interesting alternative: it has a high hydrogen density, it is available and cheap. Since the Pt electrode is sensitive to reactive substances, it must be ensured, that for example no hydrazine is produced during the ammonia cracking. A new type of ammonia cracking catalyst was investigated in this study, which unlike the conventional catalyst is not based on metal. Four different zirconium oxynitrides: ss' ZrON, ss'' ZrON, Zr{sub 2}ON{sub 2} and Zr{sub 0.88}Y{sub 0.12}O{sub 1.72}N{sub 0.15} (Y{sub 2}O{sub 3} doped ZrON) were prepared by various methods and subsequently tested for their activity in ammonia cracking. A long-term study was carried out on the best catalyst and no hydrazine was detected. On the basis of the data from the accomplished investigations a reaction mechanism is proposed. The result provides a basis for the further improvement of the catalyst. (orig.)

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

    International Nuclear Information System (INIS)

    Experiments on aqueous TiO2 photo catalytic reaction of nitrogen containing organic compounds such as ethylamine, phenylhydrazine, pyridine, urea and EDTA were carried out. Based on the values calculated for the distribution of ionic species and atomic charge, the characteristics of their photo catalytic decomposition were estimated. It was shown that the decomposition characteristics was linearly proportional to nitrogen atomic charge value. On the other hand, the effects of aqueous pH, oxygen content and concentration on the TiO2 photo catalytic characteristics of EDTA, EDTA-Cu(II) and EDTA-Fe(III) were experimentally investigated. All EDTA systems were decomposed better in the pH range of 2.5-3.0 and with more dissolved oxygen. These results could be applied to construction of a process for removal of organic impurities dissolved in a source of system water, or for treatment of EDTA-containing liquid waste produced by a chemical cleaning in the domestic NPPs. (author)

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

    Energy Technology Data Exchange (ETDEWEB)

    Sun, MIn; Perry, Kevin L.

    2015-11-20

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

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

    Institute of Scientific and Technical Information of China (English)

    Chang-Mao Hung

    2011-01-01

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

  5. 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.

  6. An Evaluation of the Vapor Phase Catalytic Ammonia Removal Process for Use in a Mars Transit Vehicle

    Science.gov (United States)

    Flynn, Michael; Borchers, Bruce

    1998-01-01

    An experimental program has been developed to evaluate the potential of the Vapor Phase Catalytic Ammonia Reduction (VPCAR) technology for use as a Mars Transit Vehicle water purification system. Design modifications which will be required to ensure proper operation of the VPCAR system in reduced gravity are also evaluated. The VPCAR system is an integrated wastewater treatment technology that combines a distillation process with high temperature catalytic oxidation. The distillation portion of the system utilizes a vapor compression distillation process to provide an energy efficient phase change separation. This portion of the system removes any inorganic salts and large molecular weight, organic contaminates, i.e., non-volatile, from the product water stream and concentrates these contaminates into a byproduct stream. To oxidize the volatile organic compounds and ammonia, a vapor phase, high temperature catalytic oxidizer is used. This catalytic system converts these compounds along with the aqueous product into CO2, H2O, and N2O. A secondary catalytic bed can then be used to reduce the N2O to nitrogen and oxygen (although not evaluated in this study). This paper describes the design specification of the VPCAR process, the relative benefits of its utilization in a Mars Transit Vehicle, and the design modification which will be required to ensure its proper operation in reduced gravity. In addition, the results of an experimental evaluation of the processors is presented. This evaluation presents the processors performance based upon product water purity, water recovery rates, and power.

  7. Spatially and size selective synthesis of Fe-based nanoparticles on ordered mesoporous supports as highly active and stable catalysts for ammonia decomposition.

    Science.gov (United States)

    Lu, An-Hui; Nitz, Joerg-Joachim; Comotti, Massimiliano; Weidenthaler, Claudia; Schlichte, Klaus; Lehmann, Christian W; Terasaki, Osamu; Schüth, Ferdi

    2010-10-13

    Uniform and highly dispersed γ-Fe(2)O(3) nanoparticles with a diameter of ∼6 nm supported on CMK-5 carbons and C/SBA-15 composites were prepared via simple impregnation and thermal treatment. The nanostructures of these materials were characterized by XRD, Mössbauer spectroscopy, XPS, SEM, TEM, and nitrogen sorption. Due to the confinement effect of the mesoporous ordered matrices, γ-Fe(2)O(3) nanoparticles were fully immobilized within the channels of the supports. Even at high Fe-loadings (up to about 12 wt %) on CMK-5 carbon no iron species were detected on the external surface of the carbon support by XPS analysis and electron microscopy. Fe(2)O(3)/CMK-5 showed the highest ammonia decomposition activity of all previously described Fe-based catalysts in this reaction. Complete ammonia decomposition was achieved at 700 °C and space velocities as high as 60,000 cm(3) g(cat)(-1) h(-1). At a space velocity of 7500 cm(3) g(cat)(-1) h(-1), complete ammonia conversion was maintained at 600 °C for 20 h. After the reaction, the immobilized γ-Fe(2)O(3) nanoparticles were found to be converted to much smaller nanoparticles (γ-Fe(2)O(3) and a small fraction of nitride), which were still embedded within the carbon matrix. The Fe(2)O(3)/CMK-5 catalyst is much more active than the benchmark NiO/Al(2)O(3) catalyst at high space velocity, due to its highly developed mesoporosity. γ-Fe(2)O(3) nanoparticles supported on carbon-silica composites are structurally much more stable over extended periods of time but less active than those supported on carbon. TEM observation reveals that iron-based nanoparticles penetrate through the carbon layer and then are anchored on the silica walls, thus preventing them from moving and sintering. In this way, the stability of the carbon-silica catalyst is improved. Comparison with the silica supported iron oxide catalyst reveals that the presence of a thin layer of carbon is essential for increased catalytic activity. PMID:20849104

  8. SCR氨区的运行维护%Operation and uphold of area of liquid ammonia in Selective Catalytic Reduction

    Institute of Scientific and Technical Information of China (English)

    陈建明

    2014-01-01

    液氨是选择性催化还原脱硝法( SCR)工艺首选的脱硝反应剂,它属于危险化学品。氨区的安全运行是SCR系统安全运行的基础保障。从氨区的运行、维护、人员防护和事故处理等方面阐述了SCR系统运行维护中需要注意的一些关键点。%Liquid ammonia is the first choice of reductant in selective catalytic reduction,it is a sort of dangerous chemical. The safe operation in the area of liquid ammonia is foundation of SCR. lt describes take notice of SCR from the operation,uphold,physical protection and accident handling in the area of liquid ammonia.

  9. Operation and uphold of area of liquid ammonia in Selective Catalytic Reduction%SCR氨区的运行维护

    Institute of Scientific and Technical Information of China (English)

    陈建明

    2014-01-01

    液氨是选择性催化还原脱硝法( SCR)工艺首选的脱硝反应剂,它属于危险化学品。氨区的安全运行是SCR系统安全运行的基础保障。从氨区的运行、维护、人员防护和事故处理等方面阐述了SCR系统运行维护中需要注意的一些关键点。%Liquid ammonia is the first choice of reductant in selective catalytic reduction,it is a sort of dangerous chemical. The safe operation in the area of liquid ammonia is foundation of SCR. lt describes take notice of SCR from the operation,uphold,physical protection and accident handling in the area of liquid ammonia.

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

    Energy Technology Data Exchange (ETDEWEB)

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

    1999-06-16

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

  11. Photoinduced catalytic synthesis of biologically important metabolites from formaldehyde and ammonia under plausible "prebiotic" conditions

    Science.gov (United States)

    Delidovich, I. V.; Taran, O. P.; Simonov, A. N.; Matvienko, L. G.; Parmon, V. N.

    2011-08-01

    The article analyzes new and previously reported data on several catalytic and photochemical processes yielding biologically important molecules. UV-irradiation of formaldehyde aqueous solution yields acetaldehyde, glyoxal, glycolaldehyde and glyceraldehyde, which can serve as precursors of more complex biochemically relevant compounds. Photolysis of aqueous solution of acetaldehyde and ammonium nitrate results in formation of alanine and pyruvic acid. Dehydration of glyceraldehyde catalyzed by zeolite HZSM-5-17 yields pyruvaldehyde. Monosaccharides are formed in the course of the phosphate-catalyzed aldol condensation reactions of glycolaldehyde, glyceraldehyde and formaldehyde. The possibility of the direct synthesis of tetroses, keto- and aldo-pentoses from pure formaldehyde due to the combination of the photochemical production of glycolahyde and phosphate-catalyzed carbohydrate chain growth is demonstrated. Erythrulose and 3-pentulose are the main products of such combined synthesis with selectivity up to 10%. Biologically relevant aldotetroses, aldo- and ketopentoses are more resistant to the photochemical destruction owing to the stabilization in hemiacetal cyclic forms. They are formed as products of isomerization of erythrulose and 3-pentulose. The conjugation of the concerned reactions results in a plausible route to the formation of sugars, amino and organic acids from formaldehyde and ammonia under presumed 'prebiotic' conditions.

  12. Mechanism of ammonia decomposition on clean and oxygen-covered Cu (1 1 1) surface: A DFT study

    International Nuclear Information System (INIS)

    Highlights: • Dehydrogenation mechanism of NH3 on clean and oxygen-covered Cu (1 1 1) was firstly studied using periodic DFT calculations. • The optimized structures and adsorption energies were obtained. • The results give the effect of using atomic oxygen to modify Cu (1 1 1) surface. • The energy barriers and reaction energies were calculated. • The existence of oxygen atom can reduce the energy barriers drastically and promote the decomposition of NHx. - Abstract: Employing density functional theory (DFT), the adsorption and dehydrogenation mechanism of ammonia on clean and O-covered Cu (1 1 1) surfaces have been studied systematically. Different adsorption geometries were investigated for NH3 and related intermediates. In addition, the stable co-adsorption configurations for the relevant co-adsorption groups were identified. The projected density of states (DOS) were calculated to understand the interaction between NHx (x = 1, 3) species and Cu (1 1 1) surface and investigate the effect of oxygen atom on adsorption. Finally, transition states, energy barriers and reaction energies were determined to confirm the mechanism of dehydrogenation of NH3 on clean and oxygen-covered Cu (1 1 1) surfaces. It was shown that NH is the most abundant intermediate on clean and O-covered Cu (1 1 1) surface due to the highest energy barrier, suggesting the dehydrogenation of NH group is the rate-determining step in the overall reaction. Furthermore, the existence of oxygen atom can reduce the energy barriers drastically and promote the decomposition of NHx (x = 1–3), indicating that ammonia decomposition is more favorable on oxygen-covered Cu (1 1 1) surface

  13. Mechanism of ammonia decomposition on clean and oxygen-covered Cu (1 1 1) surface: A DFT study

    Energy Technology Data Exchange (ETDEWEB)

    Jiang, Zhao; Qin, Pei; Fang, Tao, E-mail: taofang@mail.xjtu.edu.cn

    2014-12-05

    Highlights: • Dehydrogenation mechanism of NH{sub 3} on clean and oxygen-covered Cu (1 1 1) was firstly studied using periodic DFT calculations. • The optimized structures and adsorption energies were obtained. • The results give the effect of using atomic oxygen to modify Cu (1 1 1) surface. • The energy barriers and reaction energies were calculated. • The existence of oxygen atom can reduce the energy barriers drastically and promote the decomposition of NH{sub x}. - Abstract: Employing density functional theory (DFT), the adsorption and dehydrogenation mechanism of ammonia on clean and O-covered Cu (1 1 1) surfaces have been studied systematically. Different adsorption geometries were investigated for NH{sub 3} and related intermediates. In addition, the stable co-adsorption configurations for the relevant co-adsorption groups were identified. The projected density of states (DOS) were calculated to understand the interaction between NH{sub x} (x = 1, 3) species and Cu (1 1 1) surface and investigate the effect of oxygen atom on adsorption. Finally, transition states, energy barriers and reaction energies were determined to confirm the mechanism of dehydrogenation of NH{sub 3} on clean and oxygen-covered Cu (1 1 1) surfaces. It was shown that NH is the most abundant intermediate on clean and O-covered Cu (1 1 1) surface due to the highest energy barrier, suggesting the dehydrogenation of NH group is the rate-determining step in the overall reaction. Furthermore, the existence of oxygen atom can reduce the energy barriers drastically and promote the decomposition of NH{sub x} (x = 1–3), indicating that ammonia decomposition is more favorable on oxygen-covered Cu (1 1 1) surface.

  14. 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.

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

    DEFF Research Database (Denmark)

    Falsig, Hanne

    towards rationalizing trends in catalytic activity of transition metal catalysts for NO decomposition by combining microkinetic modelling with density functional theory calculations. We establish the full potential energy diagram for the direct NO decomposition reaction over stepped transition......The main aim of this thesis is to understand the catalytic activity of transition metals and noble metals for the direct decomposition of NO and the oxidation of CO. The formation of NOx from combustion of fossil and renewable fuels continues to be a dominant environmental issue. We take one step......-metal surfaces by combining a database of adsorption energies on stepped metal surfaces with known Brønsted–Evans–Polanyi (BEP) relations for the activation barriers of dissociation of diatomic molecules over stepped transition- and noble-metal surfaces. The potential energy diagram directly points to why Pd...

  16. Catalytic hydrolysis of ammonia borane for hydrogen generation using cobalt nanocluster catalyst supported on polydopamine functionalized multiwalled carbon nanotube

    International Nuclear Information System (INIS)

    Hydrogen was generated from ammonia borane complex by hydrolysis using cobalt nanocluster catalyst supported on polydopamine functionalized MWCNTs (multi-walled carbon nanotubes). The impregnation-chemical reduction method was used for the preparation of the supported catalyst. The nanocluster catalyst support was formed by in-situ oxidative polymerization of dopamine on the MWCNTs in alkaline solution at room temperature. The structural and physical–chemical properties of the nanocluster catalyst were characterized by FT-IR (Fourier transform infrared spectroscopy), EDX (energy-dispersive X-ray spectroscopy), SEM (scanning electron microscope), XRD (X-ray diffraction) and TEM (transmission electron microscopy). The nanocluster catalyst showed good catalytic activity for the hydrogen generation from aqueous ammonia borane complex. A reusability test to determine the practical usage of the catalyst was also investigated. The result revealed that the catalyst maintained an appreciable catalytic performance and stability in terms of its reusability after three cycle of reuse for the hydrolysis reaction. Also, the activation energy for the hydrolysis of ammonia borane complex was estimated to be 50.41 kJmol−1, which is lower than the values of some of the reported catalyst. The catalyst can be considered as a promising candidate in developing highly efficient portable hydrogen generation systems such as PEMFC (proton exchange membrane fuel cells). - Highlights: • Co/Pdop-o-MWCNT (Pdop functionalized MWCNT supported cobalt nanocluster) catalyst was synthesized for hydrogen generation. • It is an active catalyst for hydrogen generation via hydrolysis of ammonia borane. • It showed good stability in terms of reusability for the hydrogen generation

  17. Spectroscopic and Kinetic Study of Copper-Exchanged Zeolites for the Selective Catalytic Reduction of NOx with Ammonia

    OpenAIRE

    Bates, Shane Adam

    2013-01-01

    The recent application of metal-exchanged, small-pore zeolites for use in the selective catalytic reduction (SCR) of NOx with ammonia NH3 for automotive deNOx applications has been a great stride in achieving emission standard goals. Copper-exchanged SSZ-13 (Cu-SSZ-13), the small-pore zeolite in this study, has been shown to be very hydrothermally stable and active under conditions presented in the exhaust of the lean-burn diesel engine. In this work, detailed studies were performed to identi...

  18. 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

  19. Catalytic Hydrolysis of Ammonia Borane by Cobalt Nickel Nanoparticles Supported on Reduced Graphene Oxide for Hydrogen Generation

    Directory of Open Access Journals (Sweden)

    Yuwen Yang

    2014-01-01

    Full Text Available Well dispersed magnetically recyclable bimetallic CoNi nanoparticles (NPs supported on the reduced graphene oxide (RGO were synthesized by one-step in situ coreduction of aqueous solution of cobalt(II chloride, nickel (II chloride, and graphite oxide (GO with ammonia borane (AB as the reducing agent under ambient condition. The CoNi/RGO NPs exhibits excellent catalytic activity with a total turnover frequency (TOF value of 19.54 mol H2 mol catalyst−1 min−1 and a low activation energy value of 39.89 kJ mol−1 at room temperature. Additionally, the RGO supported CoNi NPs exhibit much higher catalytic activity than the monometallic and RGO-free CoNi counterparts. Moreover, the as-prepared catalysts exert satisfying durable stability and magnetically recyclability for the hydrolytic dehydrogenation of AB, which make the practical reusing application of the catalysts more convenient. The usage of the low-cost, easy-getting catalyst to realize the production of hydrogen under mild condition gives more confidence for the application of ammonia borane as a hydrogen storage material. Hence, this general method indicates that AB can be used as both a potential hydrogen storage material and an efficient reducing agent, and can be easily extended to facile preparation of other RGO-based metallic systems.

  20. 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.

  1. Iridium-decorated multiwall carbon nanotubes and its catalytic activity with Shell 405 in hydrazine decomposition

    Energy Technology Data Exchange (ETDEWEB)

    Prasad, V.; Vasanthkumar, M. S., E-mail: vasanth.physics@gmail.com [Indian Institute of Science, Department of Physics (India)

    2015-10-15

    Iridium-functionalized multiwalled carbon nanotubes (Ir-MWNT) are the future catalyst support material for hydrazine fuel decomposition. The present work demonstrates decoration of iridium particle on iron-encapsulated multiwalled carbon nanotubes (MWNT) by wet impregnation method in the absence of any stabilizer. Electron microscopy studies reveal the coated iridium particle size in the range of 5–10 nm. Elemental analysis by energy dispersive X-ray diffraction confirms 21 wt% of Ir coated over MWNT. X-ray photoelectron spectroscopy (XPS) shows 4f{sub 5/2} and 4f{sub 7/2} lines of iridium and confirms the metallic nature. The catalytic activity of Ir-MWNT/Shell 405 combination is performed in 1 N hydrazine micro-thrusters. The thruster performance shows increase in chamber pressure and decrease in chamber temperature when compared to Shell 405 alone. This enhanced performance is due to high thermal conducting nature of MWNTs and the presence of Ir active sites over MWNTs.

  2. Iridium-decorated multiwall carbon nanotubes and its catalytic activity with Shell 405 in hydrazine decomposition

    International Nuclear Information System (INIS)

    Iridium-functionalized multiwalled carbon nanotubes (Ir-MWNT) are the future catalyst support material for hydrazine fuel decomposition. The present work demonstrates decoration of iridium particle on iron-encapsulated multiwalled carbon nanotubes (MWNT) by wet impregnation method in the absence of any stabilizer. Electron microscopy studies reveal the coated iridium particle size in the range of 5–10 nm. Elemental analysis by energy dispersive X-ray diffraction confirms 21 wt% of Ir coated over MWNT. X-ray photoelectron spectroscopy (XPS) shows 4f5/2 and 4f7/2 lines of iridium and confirms the metallic nature. The catalytic activity of Ir-MWNT/Shell 405 combination is performed in 1 N hydrazine micro-thrusters. The thruster performance shows increase in chamber pressure and decrease in chamber temperature when compared to Shell 405 alone. This enhanced performance is due to high thermal conducting nature of MWNTs and the presence of Ir active sites over MWNTs

  3. [Fe-ZSM-5 catalysts with different silica-alumina ratios for N2O, catalytic decomposition].

    Science.gov (United States)

    Lu, Ren-Jie; Zhang, Xin-Yan; Hao, Zheng-Ping

    2014-01-01

    The Fe-ZSM-5 catalysts were prepared with H-ZSM-5 of different Si/Al ratios by wet ion exchange and chemical vapor deposition. Then the catalysts were investigated by XRD, BET, TEM, UV-vis and NH3-TPD technologies to analyze the iron states in Fe-ZSM-5 zeolites. The results showed that after H-ZSM-5 zeolites were prepared by chemical vapor deposition and heating wet ion exchange, the nano Fe2 O3 particles were uniformly dispersed with the sizes of 8 nm in the Fe-ZSM-5-25 (Si/A1-25). Moreover, there were more oligonuclear Fe3+ Oy clusters in the Fe-ZSM-5-25 catalysts than in Fe-ZSM-5-300 (Si/Al-300). The results of catalytic performance on N2O decomposition showed that Fe-ZSM-5-25 catalysts had higher catalytic activities than Fe-ZSM-5-300 catalysts. The Fe-ZSM-5 catalysts prepared by chemical vapor deposition achieved the best catalytic activity in N2O decomposition among the catalysts prepared by the three methods. Moreover, the presence of O2 only slightly reduced N2O conversion, while NO promoted the N2O decomposition. Finally, after reaction for more than 100 h, Fe-ZSM-5 catalyst showed no obvious deactivation under simulated emission conditions. PMID:24720229

  4. 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.

  5. New insight in the microscopic mechanism of the catalytic synthesis of ammonia

    DEFF Research Database (Denmark)

    Hansen, Flemming Yssing; Henriksen, Niels Engholm; Billing, Gert D.

    1995-01-01

    account for the observed conversion to ammonia. We have constructed an empirical potential energy surface for N-2/Fe(111) which has barriers to dissociation even larger than for the previously studied N-2/Re system. It is shown that the presence of barriers is consistent with the observation that the...

  6. Selective catalytic reduction of nitrogen oxides with ammonia over microporous zeolite catalysts

    OpenAIRE

    VENNESTROM, PETER NICOLAI RAVNBORG

    2014-01-01

    With increasing legislative demands to remove nitrogen oxides (NOx) from automotive diesel exhaust, new catalyst systems are investigated and intensely studied in industry as well in academia. The most prevailing catalytic method of choice is the selective catalytic reduction (SCR) where non-toxic urea is used as a reductant for practical reasons. Usually urea is stored in a separate tank and once injected into the exhaust system it hydrolyses into the more aggressive reductant NH3 and CO2. ...

  7. 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

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

    DEFF Research Database (Denmark)

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

    2015-01-01

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

  9. Decomposition

    Science.gov (United States)

    Middleton, Beth A.

    2014-01-01

    A cornerstone of ecosystem ecology, decomposition was recognized as a fundamental process driving the exchange of energy in ecosystems by early ecologists such as Lindeman 1942 and Odum 1960). In the history of ecology, studies of decomposition were incorporated into the International Biological Program in the 1960s to compare the nature of organic matter breakdown in various ecosystem types. Such studies still have an important role in ecological studies of today. More recent refinements have brought debates on the relative role microbes, invertebrates and environment in the breakdown and release of carbon into the atmosphere, as well as how nutrient cycling, production and other ecosystem processes regulated by decomposition may shift with climate change. Therefore, this bibliography examines the primary literature related to organic matter breakdown, but it also explores topics in which decomposition plays a key supporting role including vegetation composition, latitudinal gradients, altered ecosystems, anthropogenic impacts, carbon storage, and climate change models. Knowledge of these topics is relevant to both the study of ecosystem ecology as well projections of future conditions for human societies.

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

    Science.gov (United States)

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

    2016-07-20

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

  11. Removal of ammonia from producer gas in biomass gasification: integration of gasification optimisation and hot catalytic gas cleaning

    Energy Technology Data Exchange (ETDEWEB)

    Hongrapipat, Janjira; Saw, Woei-Lean; Pang, Shusheng [University of Canterbury, Department of Chemical and Process Engineering, Christchurch (New Zealand)

    2012-12-15

    Ammonia (NH{sub 3}) is one of the main contaminants in the biomass gasification producer gas, which is undesirable in downstream applications, and thus must be removed. When the producer gas is used in integrated gasification combined cycle (IGCC) technology, NH{sub 3} is the main precursor of nitrogen oxides (NO{sub x}) formed in gas turbine, whereas in Fischer-Tropsch synthesis and in integrated gasification fuel cell (IGFC) technology, the NH{sub 3} gas poisons the catalysts employed. This paper presents a critical review on the recent development in the understanding of the NH{sub 3} formation in biomass gasification process and in the NH{sub 3} gas cleaning technologies. The NH{sub 3} gas concentration in the producer gas can firstly be reduced by the primary measures taken in the gasification process by operation optimisation and using in-bed catalytic materials. Further removal of the NH{sub 3} gas can be implemented by the secondary measures introduced in the post-gasification gas-cleaning process. Focus is given on the catalytic gas cleaning in the secondary measures and its advantages are analysed including energy efficiency, impacts on environment and recyclability of the catalyst. Based on the review, the most effective cleaning process is proposed with integration of both the primary and the secondary measures for application in a biomass gasification process. (orig.)

  12. Understanding ammonia selective catalytic reduction kinetics over Cu-SSZ-13 from motion of the Cu ions

    Energy Technology Data Exchange (ETDEWEB)

    Gao, Feng; Walter, Eric D.; Kollar, Marton; Wang, Yilin; Szanyi, Janos; Peden, Charles HF

    2014-11-01

    Cu-SSZ-13 catalysts with three Si/Al ratios, at 6, 12 and 35, are synthesized with solution ion exchange. Catalysts are characterized with surface area/pore volume measurements, temperature programmed reduction (TPR), and electron paramagnetic resonance (EPR) spectroscopy. Catalytic properties are examined using NO oxidation, ammonia oxidation, and standard ammonia selective catalytic reduction (NH3-SCR) reactions. By varying Si/Al ratios and Cu loadings, it is possible to synthesize catalysts with one dominant type of isolated Cu2+ ion species. Prior to full dehydration of the zeolite catalyst, hydrated Cu2+ ions are found to be very mobile as judged from EPR. NO oxidation is catalyzed by O-bridged Cu-dimer species that form at relatively high Cu loadings and in the presence of O2. For NH3 oxidation and standard SCR reactions, transient Cu-dimers even form at much lower Cu loadings; and these are proposed to be the active sites for reaction temperatures ≤ 350 °C. These dimer species can be viewed as in equilibrium with monomeric Cu ion complexes. Between ~250 and 350 °C, these moieties become less stable causing SCR reaction rates to decrease. At temperatures above 350 °C and at low Cu loadings, Cu-dimers completely dissociate to regenerate isolated Cu2+ monomers that then locate at ion-exchange sites of the zeolite lattice. At low Cu loadings, these Cu species are the high-temperature active SCR catalytic centers. At high Cu loadings, on the other hand, both Cu-dimers and monomers are highly active in the high temperature kinetic regime, yet Cu-dimers are less selective in SCR. Brönsted acidity is also very important for SCR reactivity in the high-temperature regime. The authors gratefully acknowledge the US Department of Energy (DOE), Energy Efficiency and Renewable Energy, Vehicle Technologies Office for the support of this work. The research described in this paper was performed at the Environmental Molecular Sciences Laboratory (EMSL), a national

  13. 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。

  14. Catalytic oxidation of ammonia on RuO2(110) surfaces: mechanism and selectivity.

    Science.gov (United States)

    Wang, Y; Jacobi, K; Schöne, W-D; Ertl, G

    2005-04-28

    The selective oxidation of ammonia to either N2 or NO on RuO2(110) single-crystal surfaces was investigated by a combination of vibrational spectroscopy (HREELS), thermal desorption spectroscopy (TDS) and steady-state rate measurements under continuous flow conditions. The stoichiometric RuO2(110) surface exposes coordinatively unsaturated (cus) Ru atoms onto which adsorption of NH3 (NH3-cus) or dissociative adsorption of oxygen (O-cus) may occur. In the absence of O-cus, ammonia desorbs completely thermally without any reaction. However, interaction between NH3-cus and O-cus starts already at 90 K by hydrogen abstraction and hydrogenation to OH-cus, leading eventually to N-cus and H2O. The N-cus species recombine either with each other to N2 or with neighboring O-cus leading to strongly held NO-cus which desorbs around 500 K. The latter reaction is favored by higher concentrations of O-cus. Under steady-state flow condition with constant NH3 partial pressure and varying O2 pressure, the rate for N2 formation takes off first, passes through a maximum and then decreases again, whereas that for NO production exhibits an S-shape and rises continuously. In this way at 530 K almost 100% selectivity for NO formation (with fairly high reaction probability for NH3) is reached. PMID:16851919

  15. Catalyst for Ammonia Oxidation

    DEFF Research Database (Denmark)

    2015-01-01

    The present invention relates to a bimetallic catalyst for ammonia oxidation, a method for producing a bimetallic catalyst for ammonia oxidation and a method for tuning the catalytic activity of a transition metal. By depositing an overlayer of less catalytic active metal onto a more catalytic...

  16. Selective catalytic reduction of nitric oxide by ammonia over Cu-exchanged Cuban natural zeolites

    International Nuclear Information System (INIS)

    The catalytic selective reduction of NO over Cu-exchanged natural zeolites (mordenite (MP) and clinoptilolite (HC)) from Cuba using NH3 as reducing agent and in the presence of excess oxygen was studied. Cu(II)-exchanged zeolites are very active catalysts, with conversions of NO of 95%, a high selectivity to N2 at low temperatures, and exhibiting good water tolerance. The chemical state of the Cu(II) in exchanged zeolites was characterized by H2-TPR and XPS. Cu(II)-exchanged clinoptilolite underwent a severe deactivation in the presence of SO2. However, Cu(II)-exchanged mordenite not only maintained its catalytic activity, but even showed a slight improvement after 20h of reaction in the presence of 100ppm of SO2

  17. 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

  18. The role of oxygen and water on molybdenum nanoclusters for electro catalytic ammonia production

    DEFF Research Database (Denmark)

    Howalt, Jakob Geelmuyden; Vegge, Tejs

    2014-01-01

    The presence of water often gives rise to oxygen adsorption on catalyst surfaces through decomposition of water and the adsorbed oxygen or hydroxide species often occupy important surfaces sites, resulting in a decrease or a total hindrance of other chemical reactions taking place at that site....... In this study, we present theoretical investigations of the influence of oxygen adsorption and reduction on pure and nitrogen covered molybdenum nanocluster electro catalysts for electrochemical reduction of N2 to NH3 with the purpose of understanding oxygen and water poisoning of the catalyst. Density...

  19. Selective catalytic reduction of NO by ammonia over oil shale ash and fly ash catalysts

    Energy Technology Data Exchange (ETDEWEB)

    Changtao Yue; Shuyuan Li [University of Petroleum, Beijing (China). State Key Lab of Heavy Oil Processing

    2003-07-01

    Acid rain and urban air pollution, produced mainly by pollutants such as SOX and NOX and other volatile organic compounds, has become the most serious environmental problem. The selective catalytic reduction (SCR) of NO with NH{sub 3} in the presence of oxygen is a wellproven method to limit the NOX emissions. The work in this field has been the subject of much research in recent years. In this paper, NO reduction with NH{sub 3} over oil shale ash or fly ash catalysts was studied. Fe, Cu, V or Ni as active elements was loaded by adding aqueous solutions of the metal nitrate over the oil shale ash or fly ash support. The activities of the catalysts for NO removal were measured in a fixed-bed reactor. According to the results, oil shale ash or fly ash, after pre-treatment, can be reasonably used as the SCR catalyst support to remove NO from flue gas. Cu gave the highest catalytic activity and NO conversion for fly ash while V for oil shale ash. As the support, fly ash is more feasible than oil shale ash. Because of their low cost and high efficiency, the catalysts should be used in the SCR process. Further research on this subject is necessary in the future to understand more details of the SCR system and issue of pollution control. 9 refs., 2 figs., 2 tabs.

  20. 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.

  1. 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.

  2. A novel hydrolysis method to synthesize chromium hydroxide nanoparticles and its catalytic effect in the thermal decomposition of ammonium perchlorate

    International Nuclear Information System (INIS)

    Highlights: ► Synthesis of Cr(OH)3 nanoparticles in Cr3+–F− aqueous solution. ► The F− ion tailors coagulated materials, Cr(OH)3 nanoparticles are obtained. ► Adding nanosized Cr(OH)3, AP thermal decomposition temperature decreases to 200 °C. ► The nanosized Cr(OH)3 catalyzes NH3 oxidation, accelerating AP thermal decomposition. - Abstract: A procedure for the preparation of spherical Cr(OH)3 nanoparticles was developed based on the aging of chromium nitrate aqueous solutions in the presence of sodium fluoride, urea, and polyvinylpyrrolidone. Using scanning electron microscopy, transmission electron microscopy, and energy dispersive spectroscopy, the morphological characteristics of Cr(OH)3 were controlled by altering the molar ratio of fluoride ion to chromium ion, as well as the initial pH and chromium ion concentration. The prepared nanosized Cr(OH)3 decreased the temperature required to decompose ammonium perchlorate from 450 °C to about 250 °C as the catalyst. The possible catalytic mechanism of the thermal decomposition of ammonium perchlorate was also discussed.

  3. Mechanism of propene poisoning on Fe-ZSM-5 for selective catalytic reduction of NO(x) with ammonia.

    Science.gov (United States)

    Li, Junhua; Zhu, Ronghai; Cheng, Yisun; Lambert, Christine K; Yang, Ralph T

    2010-03-01

    Application of Fe-zeolites for urea-SCR of NO(x) in diesel engine is limited by catalyst deactivation with hydrocarbons. In this work, we investigated the effect of propene on the activity of Fe-ZSM-5 for selective catalytic reduction of NO(x) with ammonia (NH(3)-SCR), and proposed a deactivation mechanism of Fe(3+) active site blockage by propene residue. The NO conversion decreased in the presence of propene at various temperatures, while the effect was not significant when NO was replaced by NO(2) in the feed, especially at low temperatures (<300 degrees C). The surface area and pore volume were decreased due to carbonaceous deposition. The site blockage was mainly on Fe(3+) sites on which NO was to be oxidized to NO(2). The activity for NO oxidation to NO(2) was significantly inhibited on a propene poisoned catalyst below 400 degrees C. The adsorption of NH(3) on the Bronsted acid sites to form NH(4)(+) was not hindered even on the propene poisoned catalyst, and the amount of absorbed NH(3) was still abundant and enough to react with NO(2) to generate N(2). The hydrocarbon oxygenates such as formate, acetate, and containing nitrogen organic compounds were observed on catalyst surface, however, no graphitic carbonaceous deposit was formed. PMID:20136123

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

    Science.gov (United States)

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

    2014-01-28

    Three different types of NH3 species can be simultaneously present on Cu(2+)-exchanged CHA-type zeolites, commonly used in Ammonia Selective Catalytic Reduction (NH3-SCR) systems. These include ammonium ions (NH4(+)), formed on the Brønsted acid sites, [Cu(NH3)4](2+) complexes, resulting from NH3 coordination with the Cu(2+) Lewis sites, and NH3 adsorbed on extra-framework Al (EFAl) species, in contrast to the only two reacting NH3 species recently reported on Cu-SSZ-13 zeolite. The NH4(+) ions react very slowly in comparison to NH3 coordinated to Cu(2+) ions and are likely to contribute little to the standard NH3-SCR process, with the Brønsted groups acting primarily as NH3 storage sites. The availability/reactivity of NH4(+) ions can be however, notably improved by submitting the zeolite to repeated exchanges with Cu(2+), accompanied by a remarkable enhancement in the low temperature activity. Moreover, the presence of EFAl species could also have a positive influence on the reaction rate of the available NH4(+) ions. These results have important implications for NH3 storage and availability in Cu-Chabazite-based NH3-SCR systems. PMID:24322601

  5. 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.

  6. 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

  7. 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.

  8. 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.

  9. 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.

  10. 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. PMID:23428565

  11. 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.

  12. 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.

  13. Catalytic NO reduction with ammonia at low temperatures on V2O5/AC catalysts. Effect of metal oxides addition and SO2

    International Nuclear Information System (INIS)

    The catalytic behavior of the V-M/AC (M=W, Mo, Zr, and Sn) catalysts were studied for the NO reduction with ammonia at low temperatures, especially in the presence of SO2. The presence of the metal oxides does not increase the V2O5/AC activity but decreases it. Except V-Mo/AC, the other catalysts are promoted by SO2 at 250C, especially for V-Sn/AC. However, the promoting effect of SO2 is gradually depressed by catalyst deactivation. Changes in catalyst preparation method can improve the catalyst stability in short-term but cannot completely prevent the catalyst from a long-term deactivation. Mechanisms of the promoting effect and the deactivation of V-Sn/AC catalyst by SO2 were studied using Fourier transform infrared spectroscopy (FT-IR) spectra and measurement of catalyst surface area and pore volume. The results showed that both the SO2 promotion and deactivation are associated with the formation of sulfate species on the catalyst surface. In the initial period of the selective catalytic reduction (SCR) reaction in the presence of SO2, the formed sulfate species provide new acid sites to enhance ammonia adsorption and thus the catalytic activity. However, as the SCR reaction proceeds, excess amount of sulfate species and then ammonium-sulfate salts are formed which is stabilized by the presence of tin oxide, resulting in gradual plugging of the pore structures and the catalyst deactivation

  14. SELECTIVE CATALYTIC REDUCTION (SCR OF NO BY AMMONIA OVER V2O5/TiO2 CATALYST IN A CATALYTIC FILTER MEDIUM AND HONEYCOMB REACTOR: A KINETIC MODELING STUDY

    Directory of Open Access Journals (Sweden)

    M. Nahavandi

    2015-12-01

    Full Text Available Abstract The present study addresses a numerical modeling and simulation based on the available knowledge of SCR kinetics for prediction of NO conversion over a V2O3/TiO3 catalyst through a catalytic filter medium and honeycomb reactor. After introducing the NH3-SCR system with specific operational criteria, a reactor model was developed to evaluate the effect of various operating parameters such as flue gas temperature, velocity, NH3/NO molar ratio, etc., on the SCR process. Computational investigations were performed based on the proposed model and optimum operational conditions were identified. Simulation results indicate that SCR performance is substantially under the effects of reactant concentration and operating temperature, so that the concentration of unreacted ammonia emitted from reactor discharge (ammonia slip increases significantly at NH3/NO ratios of more than 1.14 and operating temperatures less than 360 ºC and 300 ºC, respectively, in the catalytic filter medium and honeycomb reactor. The results also show that there are three sections in NO conversion variation versus changing temperature and the required conversion with a maximum of almost 87% and low level of ammonia slip can be achieved at the NH3/NO ratio of 1 and temperature range of 240–360 ºC in both reactors.

  15. One-pot hydrothermal synthesis of CuBi co-doped mesoporous zeolite Beta for the removal of NOx by selective catalytic reduction with ammonia

    Science.gov (United States)

    Xie, Zhiguo; Zhou, Xiaoxia; Wu, Huixia; Chen, Lisong; Zhao, Han; Liu, Yan; Pan, Linyu; Chen, Hangrong

    2016-07-01

    A series of CuBi co-doped mesoporous zeolite Beta (CuxBiy-mBeta) were prepared by a facile one-pot hydrothermal treatment approach and were characterized by XRD, N2 adsorption-desorption, TEM/SEM, XPS, H2-TPR, NH3-TPD and in situ DRIFTS. The catalysts CuxBiy-mBeta were applied to the removal of NOx by selective catalytic reduction with ammonia (NH3-SCR), especially the optimized Cu1Bi1-mBeta achieved the high efficiency for the removal of NOx and N2 selectivity, superior water and sulfur resistance as well as good durability. The excellent catalytic performance could be attributed to the acid sites of the support and the synergistic effect between copper and bismuth species. Moreover, in situ DRIFTS results showed that amides NH2 and NH4+ generated from NH3 adsorption could be responsible for the high selective catalytic reduction of NOx to N2. In addition, a possible catalytic reaction mechanism on Cu1Bi1-mBeta for the removal of NOx by NH3-SCR was proposed for explaining this catalytic process.

  16. One-pot hydrothermal synthesis of CuBi co-doped mesoporous zeolite Beta for the removal of NOx by selective catalytic reduction with ammonia.

    Science.gov (United States)

    Xie, Zhiguo; Zhou, Xiaoxia; Wu, Huixia; Chen, Lisong; Zhao, Han; Liu, Yan; Pan, Linyu; Chen, Hangrong

    2016-01-01

    A series of CuBi co-doped mesoporous zeolite Beta (CuxBiy-mBeta) were prepared by a facile one-pot hydrothermal treatment approach and were characterized by XRD, N2 adsorption-desorption, TEM/SEM, XPS, H2-TPR, NH3-TPD and in situ DRIFTS. The catalysts CuxBiy-mBeta were applied to the removal of NOx by selective catalytic reduction with ammonia (NH3-SCR), especially the optimized Cu1Bi1-mBeta achieved the high efficiency for the removal of NOx and N2 selectivity, superior water and sulfur resistance as well as good durability. The excellent catalytic performance could be attributed to the acid sites of the support and the synergistic effect between copper and bismuth species. Moreover, in situ DRIFTS results showed that amides NH2 and NH4(+) generated from NH3 adsorption could be responsible for the high selective catalytic reduction of NOx to N2. In addition, a possible catalytic reaction mechanism on Cu1Bi1-mBeta for the removal of NOx by NH3-SCR was proposed for explaining this catalytic process. PMID:27445009

  17. One-pot hydrothermal synthesis of CuBi co-doped mesoporous zeolite Beta for the removal of NOx by selective catalytic reduction with ammonia

    Science.gov (United States)

    Xie, Zhiguo; Zhou, Xiaoxia; Wu, Huixia; Chen, Lisong; Zhao, Han; Liu, Yan; Pan, Linyu; Chen, Hangrong

    2016-01-01

    A series of CuBi co-doped mesoporous zeolite Beta (CuxBiy-mBeta) were prepared by a facile one-pot hydrothermal treatment approach and were characterized by XRD, N2 adsorption-desorption, TEM/SEM, XPS, H2-TPR, NH3-TPD and in situ DRIFTS. The catalysts CuxBiy-mBeta were applied to the removal of NOx by selective catalytic reduction with ammonia (NH3-SCR), especially the optimized Cu1Bi1-mBeta achieved the high efficiency for the removal of NOx and N2 selectivity, superior water and sulfur resistance as well as good durability. The excellent catalytic performance could be attributed to the acid sites of the support and the synergistic effect between copper and bismuth species. Moreover, in situ DRIFTS results showed that amides NH2 and NH4+ generated from NH3 adsorption could be responsible for the high selective catalytic reduction of NOx to N2. In addition, a possible catalytic reaction mechanism on Cu1Bi1-mBeta for the removal of NOx by NH3-SCR was proposed for explaining this catalytic process. PMID:27445009

  18. Mo-Bi系丙烯氨氧化催化剂上氨分解反应动力学的Monte Carlo模拟%Monte Carlo Simulation of Kinetics of Ammonia Oxidative Decomposition over the Commercial Propylene Ammoxidation Catalyst (Mo-Bi)

    Institute of Scientific and Technical Information of China (English)

    罗正鸿; 詹晓力; 陈丰秋; 阳永荣

    2003-01-01

    Monte Carlo method is applied to investigate the kinetics of ammonia oxidative decomposition overthe commercial propylene ammoxidation catalyst(Mo-Bi). The simulation is quite in agreement with experimentalresults. Monte Carlo simulation proves that the process of ammonia oxidation decomposition is a two-step reaction.

  19. Catalysts for Catalytic Decomposition of Nitrous Oxide%N_2O的催化分解研究

    Institute of Scientific and Technical Information of China (English)

    李孟丽; 杨晓龙; 唐立平; 熊绪茂; 任嗣利; 胡斌

    2012-01-01

    Nitrous oxide(N2O)originating from industrial and automotive emissions is accepted to be a major air pollutant. It contributes to the greenhouse effect and the depletion of stratospheric ozone. In recent years, elimination of N2O has attracted increasing attention for concerns from environment pollution. The necessity to reduce N2O emissions requires the development of catalytic technologies. Direct catalytic decomposition of N2O to N2 and O2 has been recognized as one of the most prospect methods for elimination pollution derived from N2O, since it does not require the addition of any reductant, without causing secondary pollution, and the process it concerned is simple and economical. This paper reviews the advance of several interesting catalysts that have been paid great attention in recent years, including metal oxides, noble metals and ion-exchanged zeolites catalyst systems. The advantages and disadvantages of the catalysts are also discussed in detail. This review also covers the research progress of reaction mechanism, molecular simulation and reaction kinetics on the surface of solid catalysts. Besides, the effects of moecular oxygen, water, sulfur dioxide and other species on the catalysts' activity, life and stability, are also included in this paper. The demerits exist both in these catalysts and theoretical research for the decomposition of N2O are pointed out. Finally, the trends in the catalyst system for direct catalytic decomposition of N2O are prospected.%N2O是主要的温室气体之一,它在对流层中具有破坏臭氧的作用,因此,N2O的消除越来越引起人们的重视。N2O的直接催化分解是公认的消除N2O污染的最有前景的方法之一,具有操作简单、成本低、不需引入其他杂质、不产生二次污染等特点。本文综述了近年来在N2O催化分解领域广受关注的几类催化剂的最新研究进展,包括金属氧化物催化剂、负载型贵金属催化剂

  20. Effect of the graphitic degree of carbon supports on the catalytic performance of ammonia synthesis over Ba-Ru-K/HSGC catalyst

    Institute of Scientific and Technical Information of China (English)

    Wei Jiang; Ying Li; Wenfeng Han; Yaping Zhou; Haodong Tang; Huazhang Liu

    2014-01-01

    A series of high surface area graphitic carbon materials (HSGCs) were prepared by ball-milling method. Effect of the graphitic degree of HSGCs on the catalytic performance of Ba-Ru-K/HSGC-x (x is the ball-milling time in hour) catalysts was studied using ammonia synthesis as a probe reaction. The graphitic degree and pore structure of HSGC-x supports could be successfully tuned via the variation of ball-milling time. Ru nanoparticles of different Ba-Ru-K/HSGC-x catalysts are homogeneously distributed on the supports with the particle sizes ranging from 1.6 to 2.0 nm. The graphitic degree of the support is closely related to its facile electron transfer capability and so plays an important role in improving the intrinsic catalytic performance of Ba-Ru-K/HSGC-x catalyst.

  1. 钡离子对镍基钙钛矿分解氨的影响%Decomposition of ammonia by barium ions on the nickel-based perovskite

    Institute of Scientific and Technical Information of China (English)

    陈为强; 丁彤; 马智; 谢洪燕

    2015-01-01

    镍基钙钛矿分解氨制取氢气虽有稳定性好、价格低廉的优点,但也有完全分解温度偏高的缺点。为降低完全分解氨制取氢气的温度,实验采用柠檬酸络合法,通过改变A位掺杂离子与掺杂量对LaNiO3改性,并改变载体及负载量,制备一系列的催化剂。采用XRD、SEM、TEM表征技术进行表征,考察了Ba 含量对催化剂结构与性能的影响。实验表明在催化剂装填量为1mL、空速为10000h–1、原料气为纯氨的条件下,氨分解的最佳电子助剂离子为 Ba、最优催化剂为 w(NiO)=20%的 La0.9Ba0.1NiO3/MCM-41,氨气完全分解温度由650℃降为575℃。随着Ba掺杂量的增加,催化剂活性先增加,在x=0.1达到最大值,之后减小,掺杂Ba过多催化剂的结构由钙钛矿变为非钙钛矿,非钙钛矿结构的催化剂活性不如钙钛矿。%Nickel-based perovskite catalyst,for decomposing ammonia to produce hydrogen,has good stability and low cost,but also requires high decomposition temperature. In order to reduce the complete temperature decomposition of ammonia,experiments,using citrate method,by changing the A-site doping ions and doping amounts to modify LaNiO3,were conducted with changed carriers and load amounts to prepare a series of catalysts. With XRD,SEM,TEM characterization,the effects of Ba on the structure and properties of catalyst were studied. Under the conditions of catalyst loading amount of 1mL,space velocity of 10000h-1,and pure ammonia as feed gas,the best electronic aids ions of ammonia decomposition is Ba,the best catalyst isw(NiO) = 20% of La0.9Ba0.1NiO3/MCM-41,which can make the complete decomposition temperature decrease from 650℃ to 575℃. With the increase of Ba doping amount,catalyst activity first increased,reaches a maximum atx= 0.1,and then decreased. Due to too much Ba doping,the structure of the catalyst change from perovskite to non-perovskite. The catalyst activity of perovskite is

  2. 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.

  3. Alloyed Ni-Fe nanoparticles as catalysts for NH3 decomposition

    DEFF Research Database (Denmark)

    Simonsen, Søren Bredmose; Chakraborty, Debasish; Chorkendorff, Ib;

    2012-01-01

    A rational design approach was used to develop an alloyed Ni-Fe/Al2O3 catalyst for decomposition of ammonia. The dependence of the catalytic activity is tested as a function of the Ni-to-Fe ratio, the type of Ni-Fe alloy phase, the metal loading and the type of oxide support. In the tests with high...

  4. 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.

  5. In situ formed catalytically active ruthenium nanocatalyst in room temperature dehydrogenation/dehydrocoupling of ammonia-borane from Ru(cod)(cot) precatalyst.

    Science.gov (United States)

    Zahmakiran, Mehmet; Ayvalı, Tuğçe; Philippot, Karine

    2012-03-20

    The development of simply prepared and effective catalytic materials for dehydrocoupling/dehydrogenation of ammonia-borane (AB; NH(3)BH(3)) under mild conditions remains a challenge in the field of hydrogen economy and material science. Reported herein is the discovery of in situ generated ruthenium nanocatalyst as a new catalytic system for this important reaction. They are formed in situ during the dehydrogenation of AB in THF at 25 °C in the absence of any stabilizing agent starting with homogeneous Ru(cod)(cot) precatalyst (cod = 1,5-η(2)-cyclooctadiene; cot = 1,3,5-η(3)-cyclooctatriene). The preliminary characterization of the reaction solutions and the products was done by using ICP-OES, ATR-IR, TEM, XPS, ZC-TEM, GC, EA, and (11)B, (15)N, and (1)H NMR, which reveal that ruthenium nanocatalyst is generated in situ during the dehydrogenation of AB from homogeneous Ru(cod)(cot) precatalyst and B-N polymers formed at the initial stage of the catalytic reaction take part in the stabilization of this ruthenium nanocatalyst. Moreover, following the recently updated approach (Bayram, E.; et al. J. Am. Chem. Soc.2011, 133, 18889) by performing Hg(0), CS(2) poisoning experiments, nanofiltration, time-dependent TEM analyses, and kinetic investigation of active catalyst formation to distinguish single metal or in the present case subnanometer Ru(n) cluster-based catalysis from polymetallic Ru(0)(n) nanoparticle catalysis reveals that in situ formed Ru(n) clusters (not Ru(0)(n) nanoparticles) are kinetically dominant catalytically active species in our catalytic system. The resulting ruthenium catalyst provides 120 total turnovers over 5 h with an initial turnover frequency (TOF) value of 35 h(-1) at room temperature with the generation of more than 1.0 equiv H(2) at the complete conversion of AB to polyaminoborane (PAB; [NH(2)BH(2)](n)) and polyborazylene (PB; [NHBH](n)) units. PMID:22356554

  6. Preparation of CoFe2O4 Nano crystallites by Solvo thermal Process and Its Catalytic Activity on the Thermal Decomposition of Ammonium Perchlorate

    International Nuclear Information System (INIS)

    Nanometer cobalt ferrite (CoFe2O4) was synthesized by polyol-medium solvo thermal 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 nano crystallites 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 nano crystallites 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 nano crystallites. A mechanism based on an proton transfer process has also been proposed for AP in the presence of CoFe2O4 nano crystallites.

  7. Supported Cobalt Molybdenum Bimetallic Nitrides for Ammonia Decomposition%负载型钴铜双金属氮化物催化氨分解研究

    Institute of Scientific and Technical Information of China (English)

    项益智; 李小年

    2005-01-01

    Co and Mo bimetallic nitrides supported on Mg(Al)O, MgO and γ-Al2O3 were prepared in temperatureprogrammed reactions with NH3. The surface morphology, chemical composition and catalytic activity for NH3 decomposition on the supported Co and Mo bimetallic nitrides were studied by X-ray diffractometer (XRD), NH3 temperature-programmed desorption and mass spectrometer (NH3-TPD-MS), temperature-programmed desorption and mass spectrometer (TPD-MS), H2 temperature-programmed surface reaction (H2-TPSR) and activity test.The phases of Co3MosN and MoN could be formed on Mg(Al)O, MgO and Al2O3 during the nitridation, and they might be more uniformly dispersed on Mg(Al)O and MgO than on γ-Al2O3. Transition metallic nitrides are generally considered as potential catalysts for hydrogen-involving reactions due to the entrance of hydrogen atoms into subsurface and the lattice of metallic nitrides. The diffusion of nitrogen in the bulk and the structure transformation of Co and Mo nitride compounds occur during NH3-TPD, but the supported Co and Mo bimetallic nitrides are not easily reduced at H2 atmosphere. Co3Mo3N/Mg(Al)O catalyst exhibits the highest activity, while Co3Mo3N/Al2O3 exhibits the lowest activity for NH3 decomposition. Furthermore, the catalytic activity of Co and Mo bimetallic nitrides is not only much higher than that of supported single metallic nitride, but also highly dependent upon the surface acidity and BET surface area of support.

  8. Ozone decomposition

    Science.gov (United States)

    Batakliev, Todor; Georgiev, Vladimir; Anachkov, Metody; Rakovsky, Slavcho

    2014-01-01

    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. PMID:26109880

  9. 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 (RSD<0.5%) and peak area (RSD<3%). Satisfactory extraction recoveries from spiked blanks ranged between 96 and 98%. Analyses of samples collected during transient chassis dynamometer tests of a bus engine equipped with a diesel particulate filter (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. PMID:22318005

  10. Influence of preparation conditions of hollow silica–nickel composite spheres on their catalytic activity for hydrolytic dehydrogenation of ammonia borane

    Energy Technology Data Exchange (ETDEWEB)

    Umegaki, Tetsuo, E-mail: umegaki.tetsuo@nihon-u.ac.jp [Department of Materials and Applied Chemistry, College of Science and Engineering, Nihon University, 1-8-14, Kanda-Surugadai, Chiyoda-Ku, Tokyo 101-8308 (Japan); Seki, Ayano [Department of Materials and Applied Chemistry, College of Science and Engineering, Nihon University, 1-8-14, Kanda-Surugadai, Chiyoda-Ku, Tokyo 101-8308 (Japan); Xu, Qiang [National Institute of Advanced Industrial Science and Technology (AIST), 1-8-31 Midorigaoka, Ikeda, Osaka 563-8577 (Japan); Kojima, Yoshiyuki [Department of Materials and Applied Chemistry, College of Science and Engineering, Nihon University, 1-8-14, Kanda-Surugadai, Chiyoda-Ku, Tokyo 101-8308 (Japan)

    2014-03-05

    Highlights: • We study influence of preparation conditions on activity of hollow silica–nickel composite spheres. • The activity for hydrolytic dehydrogenation of NH{sub 3}BH{sub 3} increases with increase of Si+Ni content. • The particle size distribution affects the activity and reducibility of active nickel species. • The amount of PS residue in the hollow spheres decreases by treatment of as-prepared sample in toluene. -- Abstract: In this paper, we investigated influence of preparation conditions of hollow silica–nickel composite spheres on their morphology and catalytic activity for hydrolytic dehydrogenation of ammonia borane. In the preparation method of this study, when silica–nickel composite shells were coated on polystyrene templates by the sol–gel method using L(+)-arginine as the promoter for the reaction to form silica–nickel composite shell, the polystyrene templates were dissolved subsequently, even synchronously, in the same medium to form hollow spheres. The as-prepared silica–nickel composite spheres were characterized by transmission electron microscopy and scanning electron microscopy. The effects of Si+Ni content on the morphology were systematically evaluated. All the as-prepared hollow silica–nickel composite spheres have the similar morphology as identified by SEM and TEM measurement. Homogeneity of the hollow silica–nickel composite spheres increases with the increase in the Si+Ni content as shown by the laser diffraction particle size analysis. The catalytic activities of the hollow silica–nickel composite spheres for hydrolytic dehydrogenation of ammonia borane prepared with different Si+Ni contents were compared. The catalytic activity for the hydrogen evolution in the presence of the hollow spheres increases with the increase of Si+Ni content. The results of FTIR spectra of the hollow silica–nickel composite spheres indicate that a certain amount of residual PS templates exists in hollow silica

  11. Cis-and Trans-Cinnamic Acids Have Different Effects on the Catalytic Properties of Arabidopsis Phenylalanine Ammonia Lyases PAL1, PAL2, PAL4

    Institute of Scientific and Technical Information of China (English)

    Ming-Jie CHEN; Veerappan VIJAYKUMAR; Bing-Wen LU; Bing XIA; Ning LI

    2005-01-01

    Cis-cinnamic acid (CA) is a naturally occurring compound, presumably converted from transCA in higher plants. To investigate the effect of cis-CA on the activity of Arabidopsis phenylalanine ammonia lyase (PAL), AtPAL1, AtPAL2, and AtPAL4 genes were isolated using reverse transcription polymerase chain reaction. These genes were fused to a glutathione S-transferase gene and overexpressed in a heterologous prokaryotic system of Escherichia coli. The purified PAL1, PAL2 and PAL4 enzymes were characterized biochemically to determine the effects of cis-CA on the kinetic parameter Km. The results showed that cis-CA is a competitive inhibitor for PAL1, but not PAL2 and PAL4, whereas trans-CA acts as a competitive inhibitor for all three PAL isomers, suggesting that cis- and trans-CA have different effects on the catalytic activity of PAL.

  12. 叔胺分解氟化铵制氨气和氟化氢探索研究%Study of Decomposition of Ammonium Fluoride for Production of Ammonia and Hydrogen Fluoride by Tertiary Amine

    Institute of Scientific and Technical Information of China (English)

    李德高; 梁雪松; 周艳

    2015-01-01

    This paper studied the decomposition of ammonium fluoride for production of ammonia and hydrogen fluoride.Tertiary amine as extraction agent,in the presence of water,ammonium fluoride released ammonia in a polar solvent;then adding non -polar solvents with high -boiling point,polar solvents and wa-ter was distilled;finally,at higher temperature,the decomposition of tertiary amine fluoride was achieved,hy-drogen fluoride was released;eventually,the decomposition of ammonium fluoride was reached,and the am-monia and hydrogen fluoride were stepwise released.%探索了叔胺分解氟化铵制氨气和氟化氢的方法。以叔胺作为萃取剂,在极性溶剂、水的存在下分解氟化铵释放出氨气;然后,加入高沸点的非极性溶剂蒸发出水和极性溶剂;最后,在更高的温度下,实现叔胺氟化盐的分解,释放出氟化氢;最终,达到将氟化铵分解,并分步释放出氨气和氟化氢。

  13. Mesoporous Fe-containing ZSM-5 zeolite single crystal catalysts for selective catalytic reduction of nitric oxide by ammonia

    DEFF Research Database (Denmark)

    Kustov, Arkadii; Egeblad, Kresten; Kustova, Marina;

    2007-01-01

    Mesoporous and conventional Fe-containing ZSM-5 catalysts (0.5–8 wt% Fe) were prepared using a simple impregnationmethod and tested in NO selective catalytic reduction (SCR) with NH3. It was found that mesoporous Fe-ZSM-5 catalysts exhibit higher SCR activities than comparable conventional cataly...

  14. The role of oxygen during the catalytic oxidation of ammonia on Co3O4(1 0 0)

    International Nuclear Information System (INIS)

    Graphical abstract: - Highlights: • Ammonia oxidation on Co3O4(1 0 0) surface is studied using Density Functional Theory. • The role of lattice O, on-surface O and OH in the dehydrogenation of ammonia is clarified. • NO and H2O are the main products of ammonia oxidation on Co3O4(1 0 0). • The Co3O4 surface is itself capable of oxidising NH3 to NO using the lattice O, opening the way for a Mars–van Krevelen mechanism of reaction. - Abstract: The adsorption selectivity and dehydrogenation energy barriers of NH3, NH2 and NH on the (1 0 0) surface planes of Co3O4 are determined by means of density functional methods. Stepwise hydrogen abstraction is effected by lattice O3o associated with octahedrally coordinated surface Co atoms. The final H-abstraction, from NH, leads directly to the formation of gaseous product NO with the creation of a lattice oxygen vacancy. Reaction of this vacancy with gas-phase O2 repairs the vacancy and creates surface-adsorbed O* which is also capable of abstracting H from NH3*, NH2* and NH*, the final step leading to directly again to NO formation. The mobile surface OH* formed from the O*-mediated abstraction steps is also capable of abstracting H from the NHx* species, leading ultimately to surface N* which then easily extracts a lattice O3o to form NO and a new vacancy. The overall mechanism to form NO is a complex cycle of lattice- and surface-mediated abstractions. The hydrogen budget in the reaction shows corresponding complexity. Surface H* (formed when lattice O3o abstracts H from NHx) is stable and immobile but it can be abstracted by surface OH* to form water. OH* disproportionation reaction also forms water

  15. Nanosize Control on Porous β-MnO2 and Their Catalytic Activity in CO Oxidation and N2O Decomposition

    Directory of Open Access Journals (Sweden)

    Yu Ren

    2014-05-01

    Full Text Available A major challenge in the synthesis of porous metal oxides is the control of pore size and/or wall thickness that may affect the performance of these materials. Herein, nanoporous β-MnO2 samples were prepared using different hard templates, e.g., ordered mesoporous silica SBA-15 and KIT-6, disordered mesoporous silica, and colloidal silica. These samples were characterized by Powder X-Ray Diffraction (PXRD, Transmission Electron Microscopy (TEM, and N2 adsorption-desorption. The pore size distribution of β-MnO2 was tuned by the different hard templates and their preparation details. Catalytic activities in CO oxidation and N2O decomposition were tested and the mesoporous β-MnO2 samples demonstrated superior catalytic activities compared with their bulk counterpart.

  16. 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}.

  17. 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.

  18. Influence of preparation conditions of hollow titania–nickel composite spheres on their catalytic activity for hydrolytic dehydrogenation of ammonia borane

    Energy Technology Data Exchange (ETDEWEB)

    Umegaki, Tetsuo, E-mail: umegaki.tetsuo@nihon-u.ac.jp [Department of Materials and Applied Chemistry, College of Science and Technology, Nihon University, 1-8-14, Kanda-Surugadai, Chiyoda-Ku, Tokyo 101-8308 (Japan); Ohashi, Takato [Department of Materials and Applied Chemistry, College of Science and Technology, Nihon University, 1-8-14, Kanda-Surugadai, Chiyoda-Ku, Tokyo 101-8308 (Japan); Xu, Qiang [National Institute of Advanced Industrial Science and Technology (AIST), 1-8-31 Midorigaoka, Ikeda, Osaka 563-8577 (Japan); Kojima, Yoshiyuki [Department of Materials and Applied Chemistry, College of Science and Technology, Nihon University, 1-8-14, Kanda-Surugadai, Chiyoda-Ku, Tokyo 101-8308 (Japan)

    2014-04-01

    Highlights: • We study influence of preparation conditions on activity of hollow titania–nickel composite spheres. • The activity for hydrolytic dehydrogenation of NH{sub 3}BH{sub 3} increases with increase of Ti + Ni content. • The activity depends on the amount of PS residue in the hollow spheres. - Abstract: The present work reports influence of preparation conditions of hollow titania–nickel composite spheres on their morphology and catalytic activity for hydrolytic dehydrogenation of ammonia borane (NH{sub 3}BH{sub 3}). The as-prepared hollow titania–nickel composite spheres were characterized by transmission electron microscopy (TEM). Catalytic activities of the hollow spheres for hydrolytic dehydrogenation of aqueous NaBH{sub 4}/NH{sub 3}BH{sub 3} solution improve with the decrease of Ti + Ni content. From the results of FTIR spectra and elemental analysis, the amount of residual polystyrene (PS) templates is able to be reduced by increasing aging time for the preparation, and the catalytic activity of the hollow spheres increases when the amount of residual PS templates decreases. The carbon content in the hollow spheres prepared with aging time = 24 h is 17.3 wt.%, and the evolution of 62 mL hydrogen is finished in about 22 min in the presence of the hollow spheres from aqueous NaBH{sub 4}/NH{sub 3}BH{sub 3} solution. The molar ratio of the hydrolytically generated hydrogen to the initial NH{sub 3}BH{sub 3} in the presence of the hollow spheres is 2.7.

  19. Ru-N-C Hybrid Nanocomposite for Ammonia Dehydrogenation: Influence of N-doping on Catalytic Activity

    Directory of Open Access Journals (Sweden)

    Nguyen Thi Bich Hien

    2015-06-01

    Full Text Available For application to ammonia dehydrogenation, novel Ru-based heterogeneous catalysts, Ru-N-C and Ru-C, were synthesized via simple pyrolysis of a mixture of RuCl3·6H2O and carbon black with or without dicyandiamide as a nitrogen-containing precursor at 550 °C. Characterization of the prepared Ru-N-C and Ru-C catalysts via scanning transmission electron microscopy, in conjunction with energy dispersive X-ray spectroscopy, indicated the formation of hollow nanocomposites in which the average sizes of the Ru nanoparticles were 1.3 nm and 5.1 nm, respectively. Compared to Ru-C, the Ru-N-C nanocomposites not only proved to be highly active for ammonia dehydrogenation, giving rise to a NH3 conversion of >99% at 550 °C, but also exhibited high durability. X-ray photoelectron spectroscopy revealed that the Ru active sites in Ru-N-C were electronically perturbed by the incorporated nitrogen atoms, which increased the Ru electron density and ultimately enhanced the catalyst activity.

  20. Ammonia generators for GD-KAT (advanced SCR) systems; Ammoniakgeneratoren fuer GD-KAT-Systeme

    Energy Technology Data Exchange (ETDEWEB)

    Jacob, E. [MAN Nutzfahrzeuge AG, Nuernberg (Germany)

    2004-07-01

    Catalyzed thermal decomposition of aqueous solution of urea (AdBlue) or solid urea is the preferred way to generate the reducing agent ammonia, NH{sub 3}, for selective catalytic reduction (SCR) of NO{sub x} in the diesel engine exhaust gas. Various types of decomposition reactors, called ammonia generators, are possible which differ in their effectiveness to produce ammonia from urea. For reasons of simplicity, the decomposition is usually performed by atomizing AdBlue directly into the hot exhaust. However, this technique suffers from high space velocities (SV), leading to incomplete vaporization of water and only slight decomposition into NH{sub 3} and HNCO and causing a significant performance loss of the SCR catalyst. The catalyzed thermohydrolysis out of the main exhaust stream allows much decreased SV for the urea decomposition. A catalytic reactor utilizing a partial or an auxilliary (for solid urea only) stream of the exhaust gas seems particularly promising, leading to NH{sub 3} practically free from HNCO. (orig.)

  1. 铁卟啉催化叔丁基过氧化氢分解%Catalytic Decomposition of Tert - butyl Hydroperoxide by Iron Porphyrin

    Institute of Scientific and Technical Information of China (English)

    张效龙; 王志亮; 高文斌

    2012-01-01

    Meso- tetraphenylporphyrinatoiron( Ⅲ ) chloride were prepared by Adler method and used in the catalytic decomposition of tert - butyl hydroperoxide (TBHP). Including temperature, concentration of catalyst and the initial concentration of TBHP, a wide range of experimental conditions were invested to study their effects on the decomposition rate of TBHP and the composition of products. The results demonstrated that the decomposition were straight - chain reaction which was initiated by the coordination between porphyrin and TBHP. Selectivity of tert -butyl alcohol and acetone, as well as the decomposition rate, increased under a higher temperature or catalyst concentration. Moreover, the decomposition rate was proportional to the initial concentration of TBHP and stayed constant before TBHP reduced too much.%采用Adler法合成了四苯基卟啉铁,应用于催化叔丁基过氧化氢(TBHP)分解反应。详细考察了温度、催化剂浓度及TBHP初始浓度等反应条件对分解速率、产物组成的影响。研究结果表明,TBHP分饵是由四苯基卟啉铁配位引发的直链型连锁反应,提高温度或催化剂浓度均能增大分解速率、提高反应对叔丁醇及丙酮的选择性;TBHP分解速率与其初始浓度成正比且在一定浓度范围内基本不变。

  2. Fe-MCM-41 from Coal-Series Kaolin as Catalysts for the Selective Catalytic Reduction of NO with Ammonia

    Science.gov (United States)

    Li, Shuiping; Wu, Qisheng; Lu, Guosen; Zhang, Changsen; Liu, Xueran; Cui, Chong; Yan, Zhiye

    2013-12-01

    Fe-MCM-41, one kind of high-ordered mesoporous materials catalysts, with molar ratio of Fe/Si = 0.01-0.1, was synthesized by hydrothermal method from coal-series kaolin. Fe-MCM-41 catalysts were characterized by Fourier transform infrared spectroscopy, high resolution transmission electron microscopy, N2 adsorption-desorption, x-ray photoelectron spectroscopy, and UV-vis spectroscopy. The results clearly indicated that: (1) all the samples exhibited typical hexagonal arrangement of mesoporous structure; (2) the incorporation of tiny amount of Fe3+ onto the surface and pore channel of MCM-41 mesoporous materials could efficiently promote the deNO x activity of these catalysts. Moreover, the Fe-MCM-41 mesoporous materials were evaluated in the selective catalytic reduction of NO with NH3. The results showed that Fe-MCM-41 catalyst with Fe/Si = 0.05 showed the highest catalytic activity at 350 °C, a gas hourly space velocity of 5000 h-1, n(NH3)/ n(NO) = 1.1, and O2% = 2.5%.

  3. Preparation of a highly active Fe-ZSM-5 catalyst through solid-state ion exchange for the catalytic decomposition of N{sub 2}O

    Energy Technology Data Exchange (ETDEWEB)

    Rauscher, M.; Kesore, K.; Moennig, R.; Schwieger, W. [Institut fuer Technische Chemie und Makromolekulare Chemie, Martin-Luther-Universitaet Halle-Wittenberg, Schlossberg 2, D-06108 Halle/S (Germany); Tissler, A. [ALSI-PENTA Zeolithe GmbH, Alustrasse 50-52, D-92421 Schwandorf (Germany); Turek, T. [Institut fuer Chemische Verfahrenstechnik, Universitaet Karlsruhe TH, Kaiserstrasse 12, D-76128 Karlsruhe (Germany)

    1999-08-16

    This work describes a new and simple preparation method for Fe-ZSM-5 pentasil-zeolites through solid-state ion exchange process. The zeolite catalysts thus prepared exhibit high activity during the catalytic decomposition of N{sub 2}O in the absence of reducing agents. The aimed choice of using FeSO{sub 4}x7H{sub 2}O and NH{sub 4}-ZSM-5 as starting materials consisted of forming such products (ammonium salts) after the ion exchange process that can be completely removed through thermal treatment. The complete preparation process leading to the formation of catalytically active iron species inside the zeolite takes place in two steps at two distinguished temperatures, respectively. The first step during which the solid-state ion exchange takes place has been carried out through two different routes, in air and in vacuum, in search for an enhanced catalytic activity. The second step has to be necessarily done under anaerobic conditions. XRD measurements have revealed the presence of hematite in samples with a Fe(II)/Al ratio above 0.5. The different numbers of Broensted sites occupied by the iron species in the catalysts with different Fe contents have also been determined

  4. The Effect of Copper Loading on the Selective Catalytic Reduction of Nitric Oxide by Ammonia Over Cu-SSZ-13

    Energy Technology Data Exchange (ETDEWEB)

    Kwak, Ja Hun; Tran, Diana N.; Szanyi, Janos; Peden, Charles HF; Lee, Jong H.

    2012-03-01

    The effect of Cu loading on the selective catalytic reduction of NOx by NH3 was examined over 20-80% ion-exchanged Cu-SSZ-13 zeolite catalysts. High NO reduction efficiency (80-95%) was obtained over all catalyst samples between 250 and 500°C, and the gas hourly space velocity of 200,000 h-1. Both NO reduction and NH3 oxidation activities under these conditions were found to increase slightly with increasing Cu loading at low temperatures. However, NO reduction activity was suppressed with increasing Cu loadings at high temperatures (>500oC) due to excess NH3 oxidation. The optimum Cu ion exchange level appears to be ~40-60% as higher than 80% NO reduction efficiency was obtained over 50% Cu ion-exchanged SSZ-13 up to 600oC. The NO oxidation activity of Cu-SSZ-13 was found to be low regardless of Cu loading, although it was somewhat improved with increasing Cu ion exchange level at high temperatures. During the “fast” SCR (i.e., NO/NO2 =1), only a slight improvement in NOx reduction activity was obtained for Cu-SSZ-13. Regardless of Cu loading, near 100% selectivity to N2 was observed; only a very small amount of N2O was produced even in the presence of NO2. Based on the Cu loading, the apparent activation energies for NO oxidation and NO SCR were estimated to be ~58 kJ/mol and ~41 kJ/mol, respectively.

  5. High efficiency chemical energy conversion system based on a methane catalytic decomposition reaction and two fuel cells. Part II. Exergy analysis

    Energy Technology Data Exchange (ETDEWEB)

    Liu, Qinghua; Tian, Ye; Li, Hongjiao; Jia, Lijun; Xia, Chun; Li, Yongdan [Tianjin Key Laboratory of Catalysis Science and Technology and State Key Laboratory for Chemical Engineering (Tianjin University), School of Chemical Engineering, Tianjin University, Tianjin 300072 (China); Thompson, Levi T. [Department of Chemical Engineering, University of Michigan, Ann Arbor, MI 48109-2136 (United States)

    2010-10-01

    A methane catalytic decomposition reactor-direct carbon fuel cell-internal reforming solid oxide fuel cell (MCDR-DCFC-IRSOFC) energy system is highly efficient for converting the chemical energy of methane into electrical energy. A gas turbine cycle is also used to output more power from the thermal energy generated in the IRSOFC. In part I of this work, models of the fuel cells and the system are proposed and validated. In this part, exergy conservation analysis is carried out based on the developed electrochemical and thermodynamic models. The ratio of the exergy destruction of each unit is examined. The results show that the electrical exergy efficiency of 68.24% is achieved with the system. The possibility of further recovery of the waste heat is discussed and the combined power-heat exergy efficiency is over 80%. (author)

  6. 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.

  7. 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].

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

    International Nuclear Information System (INIS)

    In an experiment on TiO2 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) = δ (ε - a )1/3 + b where, ε : atomic charge of nitrogen in a molecular, δ, a and b : corrective coefficients

  9. Characterization and catalytic behavior of CuO rate at SiO{sub 2} nanocomposites towards NO oxidation and N{sub 2}O decomposition

    Energy Technology Data Exchange (ETDEWEB)

    Tohidi, Seyed H.; Derhambakhsh, Maryam [Materials Research School, Karaj (Iran, Islamic Republic of). Nuclear Science and Technology Inst.; Grigoryan, Garnik L. [Yerevan State Univ. (Armenia). Inorganic Faculty

    2012-08-15

    A distinct concentration of copper was embedded into silica matrix to form xerogel using Cu(NO{sub 3}){sub 2} . 3H{sub 2}O as the copper source. The xerogel samples were prepared by hydrolysis and condensation of tetraethyl orthosilicate (TEOS) by the sol-gel method. The new molar ratio of H{sub 2}O/TEOS was determined to be 11.67. Also the necessary amount of trihydrated copper nitrate was added into the solution such that the concentration of the copper oxide in the final solution reached 10 wt.%. After ambient drying, the xerogel samples were heated to 100, 400, 600, 800, and 1 000 C at a slow heating rate (50 K h{sup -1}). The structural properties were characterized by means of transmission electron microscopy, surface analysis and thermal program reduction methods at different temperatures. Finally, the catalytic behavior of nanocomposites was studied for nitrogen oxide (NO) oxidation and di-nitrogen oxide (N{sub 2}O) decomposition reactions. The results present a systematic reactivity study of NO oxidation and N{sub 2}O decomposition on the dispersed copper oxide nanocatalysts over silica supports in order to determine the ability of these materials to convert nitrogen oxide and di-nitrogen oxide into harmless species at different temperatures. (orig.)

  10. 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.

  11. 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.

  12. A novel ammonia-assisted method for the direct synthesis of Mn3O4 nanoparticles at room temperature and their catalytic activity during the rapid degradation of azo dyes

    Science.gov (United States)

    Mansournia, Mohammadreza; Azizi, Fatemeh; Rakhshan, Narges

    2015-05-01

    In this study, we prepared trimanganese tetroxide nanoparticles from MnCl2 solution in an ammonia atmosphere using a new surfactant-free method at room temperature. We analyzed and characterized the effects of different processing conditions, such as the concentrations of manganese and the ammonia source, as well as the reaction time, on the structure, purity, and morphology of the products using powder X-ray diffraction (XRD), scanning electron microscopy, and Fourier transformation infrared spectroscopy (FTIR) techniques. The XRD and FTIR analyses confirmed that the prepared products comprised single phase Mn3O4. At room temperature, the paramagnetic characteristics were also verified by vibrating sample magnetometry. Furthermore, we tested the catalytic activity of the nanoparticles during the degradation of methyl orange and Congo red, which are organic pollutants. Our experiments demonstrated the rapid color removal and reduction in the chemical oxygen demand (>70% and >50% within 10 min, respectively) using aqueous solutions of azo dyes.

  13. 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).

  14. 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).

  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. Silver-mordenite for radiologic gas capture from complex streams. Dual catalytic CH3I decomposition and I confinement

    International Nuclear Information System (INIS)

    The selective capture of radiological iodine (129I) is a persistent concern for safe nuclear energy. In these nuclear fuel reprocessing scenarios, the gas streams to be treated are extremely complex, containing several distinct iodine-containing molecules amongst a large variety of other species. Silver-containing mordenite (MOR) is a longstanding benchmark for radioiodine capture, reacting with molecular iodine (I2) to form AgI. However the mechanisms for organoiodine capture is not well understood. Here we investigate the capture of methyl iodide from complex mixed gas streams by combining chemical analysis of the effluent gas stream with in depth characterization of the recovered sorbent. Tools applied include infrared spectroscopy, thermogravimetric analysis with mass spectrometry, micro X-ray fluorescence, powder X-ray diffraction analysis, and pair distribution function analysis. Moreover, the MOR zeolite catalyzes decomposition of the methyl iodide through formation of surface methoxy species (SMS), which subsequently reacts with water in the mixed gas stream to form methanol, and with methanol to form dimethyl ether, which are both detected downstream in the effluent. The liberated iodine reacts with Ag in the MOR pore to the form subnanometer AgI clusters, smaller than the MOR pores, suggesting that the iodine is both physically and chemically confined within the zeolite

  17. [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.

  18. Scanning electrochemical microscopy: surface interrogation of adsorbed hydrogen and the open circuit catalytic decomposition of formic acid at platinum.

    Science.gov (United States)

    Rodríguez-López, Joaquín; Bard, Allen J

    2010-04-14

    The surface interrogation mode of scanning electrochemical microscopy (SECM) is extended to the in situ quantification of adsorbed hydrogen, H(ads), at polycrystalline platinum. The methodology consists of the production, at an interrogator electrode, of an oxidized species that is able to react with H(ads) on the Pt surface and report the amounts of this adsorbate through the SECM feedback response. The technique is validated by comparison to the electrochemical underpotential deposition (UPD) of hydrogen on Pt. We include an evaluation of electrochemical mediators for their use as oxidizing reporters for adsorbed species at platinum; a notable finding is the ability of tetramethyl-p-phenylenediamine (TMPD) to oxidize (interrogate) H(ads) on Pt at low pH (0.5 M H(2)SO(4) or 1 M HClO(4)) and with minimal background effects. As a case study, the decomposition of formic acid (HCOOH) in acidic media at open circuit on Pt was investigated. Our results suggest that formic acid decomposes at the surface of unbiased Pt through a dehydrogenation route to yield H(ads) at the Pt surface. The amount of H(ads) depended on the open circuit potential (OCP) of the Pt electrode at the time of interrogation; at a fixed concentration of HCOOH, a more negative OCP yielded larger amounts of H(ads) until reaching a coulomb limiting coverage close to 1 UPD monolayer of H(ads). The introduction of oxygen into the cell shifted the OCP to more positive potentials and reduced the quantified H(ads); furthermore, the system was shown to be chemically reversible, as several interrogations could be run consecutively and reproducibly regardless of the path taken to reach a given OCP. PMID:20225806

  19. High efficiency chemical energy conversion system based on a methane catalytic decomposition reaction and two fuel cells: Part I. Process modeling and validation

    Energy Technology Data Exchange (ETDEWEB)

    Liu, Qinghua; Tian, Ye; Li, Hongjiao; Jia, Lijun; Xia, Chun; Li, Yongdan [Tianjin Key Laboratory of Catalysis Science and Technology and State Key Laboratory for Chemical Engineering (Tianjin University), School of Chemical Engineering, Tianjin University, Tianjin 300072 (China); Thompson, Levi T. [Department of Chemical Engineering, University of Michigan, Ann Arbor, MI 48109-2136 (United States)

    2010-10-01

    A highly efficient integrated energy conversion system is built based on a methane catalytic decomposition reactor (MCDR) together with a direct carbon fuel cell (DCFC) and an internal reforming solid oxide fuel cell (IRSOFC). In the MCDR, methane is decomposed to pure carbon and hydrogen. Carbon is used as the fuel of DCFC to generate power and produce pure carbon dioxide. The hydrogen and unconverted methane are used as the fuel in the IRSOFC. A gas turbine cycle is also used to produce more power output from the thermal energy generated in the IRSOFC. The output performance and efficiency of both the DCFC and IRSOFC are investigated and compared by development of exact models of them. It is found that this system has a unique loading flexibility due to the good high-loading property of DCFC and the good low loading property of IRSOFC. The effects of temperature, pressure, current densities, and methane conversion on the performance of the fuel cells and the system are discussed. The CO{sub 2} emission reduction is effective, up to 80%, can be reduced with the proposed system. (author)

  20. Catalytic decomposition of gaseous PCDD/Fs over V2O5/TiO2-CNTs catalyst: Effect of NO and NH3 addition.

    Science.gov (United States)

    Wang, Qiulin; Hung, Pao Chang; Lu, Shengyong; Chang, Moo Been

    2016-09-01

    There is a strong need for a control technology that simultaneously achieving the abatement of PCDD/Fs (polychlorinated dibenzo-p-dioxins and polychlorinated dibenzofurans) and nitrogen oxides (NOx) emissions in waste incineration industry. TiO2 and carbon nanotubes (CNTs) were used as composite carriers to support vanadium oxide as an innovative catalyst to simultaneously control PCDD/Fs and NO emissions. The removal efficiencies (RE) of PCDD/Fs by V2O5/TiO2-CNTs catalyst under a space velocity (SV) of 20,000 h(-1) reaches 99.9% at 150 °C and adsorption is supposed to be the main mechanism at this temperature. The influence of NONH3 reaction on PCDD/Fs catalytic reaction is investigated. The kinetics analysis exhibits that the addition of NO and NH3 reduces the activation energies for OCDD (octachlorodibenzo-p-dioxin) and OCDF (octachlorodibenzofuran) decomposition to 3.6 kJ/mol and 5.4 kJ/mol respectively. PMID:27285382

  1. Carbon nanofibers: a versatile catalytic support

    Directory of Open Access Journals (Sweden)

    Nelize Maria de Almeida Coelho

    2008-09-01

    Full Text Available The aim of this article is present an overview of the promising results obtained while using carbon nanofibers based composites as catalyst support for different practical applications: hydrazine decomposition, styrene synthesis, direct oxidation of H2S into elementary sulfur and as fuel-cell electrodes. We have also discussed some prospects of the use of these new materials in total combustion of methane and in ammonia decomposition. The macroscopic carbon nanofibers based composites were prepared by the CVD method (Carbon Vapor Deposition employing a gaseous mixture of hydrogen and ethane. The results showed a high catalytic activity and selectivity in comparison to the traditional catalysts employed in these reactions. The fact was attributed, mainly, to the morphology and the high external surface of the catalyst support.

  2. 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.

  3. 鸟粪石循环利用处理高氨氮废水的热解行为%Thermal decomposition behavior of struvite in recycling treatment of high ammonia-nitrogen wastewater

    Institute of Scientific and Technical Information of China (English)

    曾庆玲; 王露; 沈春花; 李飞

    2013-01-01

    In order to treat high ammonia-nitrogen wastewater by struvite reuse,the thermal decomposition of struvite was studied.The denitrification rates of struvite were studied by calcination and heat under alkali conditions separately.The thermal decomposition residues were analyzed by scanning electron microscope (SEM)and X-ray diffraction (XRD).The temperature for struvite calcination was between 100 ~225℃ ; calcination time ranged from 1 ~ 5 hours.When the struvite was heated under alkali conditions,the temperature was between 60 ~ 95 ℃ ; the molar ratio of OH-∶ NH4+ was 0.4 ~ 1.5 ; and heated time was 0.5 ~ 4 hours.Analysis with XRD showed that the characteristic peaks of struvite were absent in both the two kinds of thermal decomposition residues,but the alkali method was better.The denitrification rate of struvite could reach 95 % under alkali conditions,when OH-∶ NH4+ molar ratio was 1,temperature was 90℃ and being heated for 2 hours.SEM analysis showed that the thermal decomposition residues was porous surface and lost crystal structure completely under alkali conditions,but the crystal structure was not destroyed completely when struvite was calcined with a denitrification rate of 80% only.The struvite could be reused for six times for the high ammonia-nitrogen wastewater treatment under best condition,with a removal rate of ammonia-nitrogen over 80%,and the concentration of phosphate was lower than 8 mg/L.%为了循环利用鸟粪石处理高氨氮废水,探讨了鸟粪石煅烧与加碱热解的脱氮率,利用电镜扫描(SEM)和X射线衍射(XRD)对2种热解产物进行了分析.鸟粪石煅烧条件为:温度100~ 225℃,时间1~5h;加碱热解条件为:温度60~95℃,时间0.5~4h,加碱量OH-∶NH4摩尔比值0.4 ~1.5.结果表明,虽然XRD分析显示2种热解产物都已失去鸟粪石的特征峰,但是鸟粪石加碱热解效果更好,最佳热解条件为:加碱量OH-∶NH4摩尔比值1,温度90℃,时间2h

  4. Ammonia as efficient fuel for SOFC

    Energy Technology Data Exchange (ETDEWEB)

    Fuerte, A.; Valenzuela, R.X.; Escudero, M.J. [CIEMAT, Departamento de Energia, Av. Complutense 22, 28040 Madrid (Spain); Daza, L. [CIEMAT, Departamento de Energia, Av. Complutense 22, 28040 Madrid (Spain); Instituto de Catalisis y Petroleoquimica (CSIC), C/Marie Curie 2, Campus Cantoblanco, 28049 Madrid (Spain)

    2009-07-01

    Ammonia is a possible candidate as the fuel for SOFCs. In this work, the influence on the performance of a tubular SOFC running on ammonia is studied. Analysis of open circuit voltages (OCVs) on the cell indicated the oxidation of ammonia within a SOFC is a two-stage process: decomposition of the inlet ammonia into nitrogen and hydrogen, followed by oxidation of hydrogen to water. For comparison, cell was also tested with hydrogen as the fuel and air as oxidant at different temperatures showing a similar behaviour. The performance of the cell tested under various conditions shows the high potential of ammonia as fuel for SOFCs. (author)

  5. Promoted Ru on high-surface area graphite for efficient miniaturized production of hydrogen from ammonia

    DEFF Research Database (Denmark)

    Sørensen, Rasmus Zink; Klerke, Asbjørn; Quaade, Ulrich;

    2006-01-01

    Promoted Ru/C catalysts for decomposition of ammonia are incorporated into micro-fabricated reactors for the first time. With the reported preparation technique, the performance is increased more than two orders of magnitude compared to previously known micro-fabricated reactors for ammonia...... studies of both ammonia synthesis and decomposition, and it is shown how proper promotion can facilitate ammonia decomposition at temperatures below 500 K....

  6. High Iron Containing Sphalerite Concentrate by Catalytic Oxidation under High Pressure Oxygen and Ammonia Water Leaching%高铁闪锌矿精矿高氧催化氧化氨浸工艺试验

    Institute of Scientific and Technical Information of China (English)

    王书民; 樊雪梅; 张国春; 郑行望

    2011-01-01

    The optimal condition for the ammonia catalytic oxidation of the high iron containing sphalerite with high pressure oxygen is investigated by orthogonal experiment using table of L25(56). The results show that the leaching rates of zinc, copper, cadmium from the high iron containing sphalerite are up 93% , 94% and 91% , respectively, by salvolatile-ammonia water-perhydrol-catalyst system under the condition of 25℃ , 600kPa oxygen partial pressure, 7. 0 L/S ratio, leaching time 8h, and there is no iron in solution.%采用L25( 56)正交设计表,研究高铁闪锌矿精矿高氧催化氧化氨浸工艺的最佳工艺条件.结果表明,在25℃、氧分压为600kPa、液固比为7.0条件下,以碳铵-氨水-双氧水-催化剂体系氧化浸出高铁闪锌矿精矿8h,锌、铜、镉的浸出率分别可以达到93%,94%,91%,浸取液中不含铁.

  7. Direct observation of low-temperature catalytic decomposition of H{sub 3}BO{sub 3} shell in core/shell Ni/H{sub 3}BO{sub 3} nanoparticles

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, X.F. [Dalian University of Technology, School of Materials Science and Engineering, Dalian, Liaoning (China); Industrial Materials Institute, National Research Council of Canada, Boucherville, Quebec (Canada); Guan, P.F. [Tohoku University, World Premier International Research Center, Advanced Institute for Materials Research, Sendai (Japan); Dong, X.L. [Dalian University of Technology, School of Materials Science and Engineering, Dalian, Liaoning (China)

    2012-08-15

    Decomposition of H{sub 3}BO{sub 3} to B{sub 2}O{sub 3} in core/shell Ni/H{sub 3}BO{sub 3} nanoparticles was in situ recorded by transmission electron microscope as the irradiation time. The direct observation provides compelling evidence of the synergetic effect of the Ni core and the H{sub 3}BO{sub 3} shell, revealing the catalytic mechanisms of metal nanostructures that induce the decomposition at 124 C, lower than the bulk counterpart at 300 C. This phenomenon can be theoretically explained by considering the weakening of B-O bond at the Ni-H{sub 3}BO{sub 3} interface, and has important implications in understanding the lubricant behavior of H{sub 3}BO{sub 3} in frictional wear. (orig.)

  8. 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.

  9. Electroreduction of N2 to ammonia at ambient conditions on mononitrides of Zr, Nb, Cr, and V – A DFT guide for experiments

    DEFF Research Database (Denmark)

    Abghoui, Younes; Garden, Anna L.; Howalt, Jakob Geelmuyden;

    2016-01-01

    . Particular single-crystal surfaces are needed for ZrN, NbN and CrN because polycrystalline surfaces may result in decomposition of the whole catalyst. Polycrystalline surfaces of VN may, however, be used since the rocksalt (100) facet is predicted to produce ammonia via a Mars-van Krevelen mechanism...... benefit to the present analysis is that the method used in this work may be applicable to other aqueous phase catalytic reactions, where a Mars-van Krevelen mechanism is operative and product selectivity and activity are key catalytic criteria....

  10. Catalytic hot gas cleaning of gasification gas

    Energy Technology Data Exchange (ETDEWEB)

    Simell, P. [VTT Energy, Espoo (Finland). Energy Production Technologies

    1997-12-31

    The aim of this work was to study the catalytic cleaning of gasification gas from tars and ammonia. In addition, factors influencing catalytic activity in industrial applications were studied, as well as the effects of different operation conditions and limits. Also the catalytic reactions of tar and ammonia with gasification gas components were studied. The activities of different catalyst materials were measured with laboratory-scale reactors fed by slip streams taken from updraft and fluid bed gasifiers. Carbonate rocks and nickel catalysts proved to be active tar decomposing catalysts. Ammonia decomposition was in turn facilitated by nickel catalysts and iron materials like iron sinter and iron dolomite. Temperatures over 850 deg C were required at 2000{sup -1} space velocity at ambient pressure to achieve almost complete conversions. During catalytic reactions H{sub 2} and CO were formed and H{sub 2}O was consumed in addition to decomposing hydrocarbons and ammonia. Equilibrium gas composition was almost achieved with nickel catalysts at 900 deg C. No deactivation by H{sub 2}S or carbon took place in these conditions. Catalyst blocking by particulates was avoided by using a monolith type of catalyst. The apparent first order kinetic parameters were determined for the most active materials. The activities of dolomite, nickel catalyst and reference materials were measured in different gas atmospheres using laboratory apparatus. This consisted of nitrogen carrier, toluene as tar model compound, ammonia and one of the components H{sub 2}, H{sub 2}O, CO, CO{sub 2}, CO{sub 2}+H{sub 2}O or CO+CO{sub 2}. Also synthetic gasification gas was used. With the dolomite and nickel catalyst the highest toluene decomposition rates were measured with CO{sub 2} and H{sub 2}O. In gasification gas, however, the rate was retarded due to inhibition by reaction products (CO, H{sub 2}, CO{sub 2}). Tar decomposition over dolomite was modelled by benzene reactions with CO{sub 2}, H

  11. Synthesis and characterization of Fe–Ni/ɣ-Al2O3 egg-shell catalyst for H2 generation by ammonia decomposition

    DEFF Research Database (Denmark)

    Silva, Hugo José Lopes; Nielsen, Morten Godtfred; Fiordaliso, Elisabetta Maria;

    2015-01-01

    of the active phase should match with the type of reaction. In this work, a novel synthesis route was developed for the preparation of a Fe–Ni/ɣ-Al2O3 egg-shell catalyst. Egg-shell is a preferred profile considering the highly endothermic nature of ammonia decomposition reaction. The high viscosity of glycerol......, used as a solvent during impregnation, prevents the fast migration of the Fe–Ni active phase solution toward the inner-core of ɣ-Al2O3, giving control over the large capillary pressures. The distribution profiles were analyzed at macroscopic scale through scanning electron microscopy mapping (SEM......-EDX) and optical microscopy. A three-dimensional (3-D) reconstruction of the spherical-shaped ɣ-Al2O3 was achieved using X-ray micro tomography and the Fe–Ni egg-shell spatial distribution was inspected throughout the entire volume of the support body. Transmission electron microscopy (TEM) specimen preparation...

  12. The role of oxygen during the catalytic oxidation of ammonia on Co{sub 3}O{sub 4}(1 0 0)

    Energy Technology Data Exchange (ETDEWEB)

    Shojaee, Kambiz; Haynes, Brian S.; Montoya, Alejandro, E-mail: alejandro.montoya@sydney.edu.au

    2014-10-15

    Graphical abstract: - Highlights: • Ammonia oxidation on Co{sub 3}O{sub 4}(1 0 0) surface is studied using Density Functional Theory. • The role of lattice O, on-surface O and OH in the dehydrogenation of ammonia is clarified. • NO and H{sub 2}O are the main products of ammonia oxidation on Co{sub 3}O{sub 4}(1 0 0). • The Co{sub 3}O{sub 4} surface is itself capable of oxidising NH{sub 3} to NO using the lattice O, opening the way for a Mars–van Krevelen mechanism of reaction. - Abstract: The adsorption selectivity and dehydrogenation energy barriers of NH{sub 3}, NH{sub 2} and NH on the (1 0 0) surface planes of Co{sub 3}O{sub 4} are determined by means of density functional methods. Stepwise hydrogen abstraction is effected by lattice O{sup 3o} associated with octahedrally coordinated surface Co atoms. The final H-abstraction, from NH, leads directly to the formation of gaseous product NO with the creation of a lattice oxygen vacancy. Reaction of this vacancy with gas-phase O{sub 2} repairs the vacancy and creates surface-adsorbed O{sup *} which is also capable of abstracting H from NH{sub 3}{sup *}, NH{sub 2}{sup *} and NH{sup *}, the final step leading to directly again to NO formation. The mobile surface OH{sup *} formed from the O{sup *}-mediated abstraction steps is also capable of abstracting H from the NH{sub x}{sup *} species, leading ultimately to surface N{sup *} which then easily extracts a lattice O{sup 3o} to form NO and a new vacancy. The overall mechanism to form NO is a complex cycle of lattice- and surface-mediated abstractions. The hydrogen budget in the reaction shows corresponding complexity. Surface H{sup *} (formed when lattice O{sup 3o} abstracts H from NH{sub x}) is stable and immobile but it can be abstracted by surface OH{sup *} to form water. OH{sup *} disproportionation reaction also forms water.

  13. Catalytic distillation water recovery subsystem

    Science.gov (United States)

    Budininkas, P.; Rasouli, F.

    1985-01-01

    An integrated engineering breadboard subsystem for the recovery of potable water from untreated urine based on the vapor phase catalytic ammonia removal was designed, fabricated and tested. Unlike other evaporative methods, this process catalytically oxidizes ammonia and volatile hydrocarbons vaporizing with water to innocuous products; therefore, no pretreatment of urine is required. Since the subsystem is fabricated from commercially available components, its volume, weight and power requirements are not optimized; however, it is suitable for zero-g operation. The testing program consists of parametric tests, one month of daily tests and a continuous test of 168 hours duration. The recovered water is clear, odorless, low in ammonia and organic carbon, and requires only an adjustment of its pH to meet potable water standards. The obtained data indicate that the vapor phase catalytic ammonia removal process, if further developed, would also be competitive with other water recovery systems in weight, volume and power requirements.

  14. Application of transition metal ferrites AFe2O4 (A= Co, Ni, Cu) for the catalytic decomposition of sulphuric acid involved in sulphur-iodine thermochemical cycle for nuclear hydrogen production

    International Nuclear Information System (INIS)

    Spinel ferrites with general formula AFe2O4 (A= Co, Ni, Cu) were prepared by glycine-nitrate gel combustion method and characterized using powder XRD, FTIR, SEM and Mossbauer spectroscopy. The redox properties of the samples were studied by recording multiple TPR/O cycles. The copper ferrite sample was found to be the most easily reducible sample with Tmax for reduction occurring at the lowest temperature among all samples. The catalytic activity of all the samples were evaluated for sulphuric acid decomposition reaction in the temperature range of 650 deg C-825 deg C. Copper ferrite was found to be the most active catalyst for the reaction with ∼ 78% conversion at 800 deg C. (author)

  15. Identification of the arsenic resistance on MoO3 doped CeO2/TiO2 catalyst for selective catalytic reduction of NOx with ammonia.

    Science.gov (United States)

    Li, Xiang; Li, Xiansheng; Li, Junhua; Hao, Jiming

    2016-11-15

    Arsenic resistance on MoO3 doped CeO2/TiO2 catalysts for selective catalytic reduction of NOx with NH3 (NH3-SCR) is investigated. It is found that the activity loss of CeO2-MoO3/TiO2 caused by As oxide is obvious less than that of CeO2/TiO2 catalysts. The fresh and poisoned catalysts are compared and analyzed using XRD, Raman, XPS, H2-TPR and in situ DRIFTS. The results manifest that the introduction of arsenic oxide to CeO2/TiO2 catalyst not only weakens BET surface area, surface acid sites and adsorbed NOx species, but also destroy the redox circle of Ce(4+) to Ce(3+) because of interaction between Ce and As. When MoO3 is added into CeO2/TiO2 system, the main SCR reaction path are found to be changed from the reaction between coordinated NH3 and ad-NOx species to that between an amide and gaseous NO. Additionally, for CeO2-MoO3/TiO2 catalyst, As toxic effect on active sites CeO2 can be released because of stronger As-Mo interaction. Moreover, not only are the reactable Brønsted and Lewis acid sites partly restored, but the cycle of Ce(4+) to Ce(3+) can also be free to some extent.

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

    OpenAIRE

    Lili Ren; Jin Zhang

    2012-01-01

    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.

  17. 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.

  18. 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.

  19. 微波辐射与常规加热下催化分解NO动力学比较%ComParison of Dynamics of Catalytic DecomPosition of NO under Microwave Radiation or Conventional Heating

    Institute of Scientific and Technical Information of China (English)

    阳鹏飞; 周继承; 王宏礼

    2014-01-01

    The microwave synergistic catalytic decomposition of NO in a new microwave catalytic reactor with Cu/ZSM_5 catalyst was studied. The kinetics of catalytic decomposi_tion of NO under microwave synergistic condition was discussed,and has been compared with it under the conventional heating condition. The results indicate that:the activation energy of that reaction is 14. 6 kJ/mol under the microwave radiation conditions,while un_der the conventional heating conditions,it is 75. 6 kJ/mol. The activation energy of that re_action under conventional heating was 5 . 177 times higher than that under microwave heat_ing . According to these results,it has been proved that the microwave irradiation has micro_ wave catalysis effect besides thermal effect.%以Cu/ZSM_5为催化剂,在新型微波催化反应器上进行了微波协同催化分解NO反应.初步探讨了微波协同催化分解NO反应的宏观动力学,并与常规加热条件下催化分解NO反应的宏观动力进行了对比.计算结果表明:在微波辐射条件下,该反应的活化能为14.6 kJ/mol.而常规加热条件下,该反应的活化能为75.6 kJ/mol.微波辐射条件下该反应活化能仅仅是常规加热条件下该反应活化能的1/5.177.这说明微波作用不仅具有致热效应,而且大大降低了反应活化能,具有微波催化效应.

  20. 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.

  1. Microwave-assisted synthesis of carbon-supported carbides catalysts for hydrous hydrazine decomposition

    Science.gov (United States)

    Mnatsakanyan, Raman; Zhurnachyan, Alina R.; Matyshak, Valery A.; Manukyan, Khachatur V.; Mukasyan, Alexander S.

    2016-09-01

    Microwave-assisted synthesis of carbon-supported Mo2C and WC nanomaterials was studied. Two different routes were utilized to prepare MoO3 (WO3) - C precursors that were then subjected to microwave irradiation in an inert atmosphere. The effect of synthesis conditions, such as irradiation time and gas environment, was investigated. The structure and formation mechanism of the carbide phases were explored. As-synthesized nanomaterials exhibited catalytic activity for hydrous hydrazine (N2H4·H2O) decomposition at 30-70 °C. It was shown that the catalyst activity significantly increases if microwave irradiation is applied during the decomposition process. Such conditions permit complete conversion of hydrazine to ammonia and nitrogen within minutes. This effect can be attributed to the unique nanostructure of the catalysts that includes microwave absorbing carbon and active carbide constituents.

  2. 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.

  3. 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 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. PMID:26903086

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

    Energy Technology Data Exchange (ETDEWEB)

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

    1996-12-01

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

  5. 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.

  6. The structure-function relationship for alumina supported platinum during the formation of ammonia from nitrogen oxide and hydrogen in the presence of oxygen.

    Science.gov (United States)

    Adams, Emma Catherine; Merte, Lindsay Richard; Hellman, Anders; Skoglundh, Magnus; Gustafson, Johan; Bendixen, Eva Charlotte; Gabrielsson, Pär; Bertram, Florian; Evertsson, Jonas; Zhang, Chu; Carlson, Stefan; Carlsson, Per-Anders

    2016-04-28

    We study the structure-function relationship of alumina supported platinum during the formation of ammonia from nitrogen oxide and dihydrogen by employing in situ X-ray absorption and Fourier transform infrared spectroscopy. Particular focus has been directed towards the effect of oxygen on the reaction as a model system for emerging technologies for passive selective catalytic reduction of nitrogen oxides. The suppressed formation of ammonia observed as the feed becomes net-oxidizing is accompanied by a considerable increase in the oxidation state of platinum as well as the formation of surface nitrates and the loss of NH-containing surface species. In the presence of (excess) oxygen, the ammonia formation is proposed to be limited by weak interaction between nitrogen oxide and the oxidized platinum surface. This leads to a slow dissociation rate of nitrogen oxide and thus low abundance of the atomic nitrogen surface species that can react with the adsorbed hydrogen species. In this case the consumption of hydrogen through the competing water formation reaction and decomposition/oxidation of ammonia are of less importance for the net ammonia formation. PMID:27039829

  7. Ammonia measurement with a pH electrode in the ammonia/urea-SCR process

    Science.gov (United States)

    Kröcher, Oliver; Elsener, Martin

    2007-03-01

    The selective catalytic reduction of nitrogen oxides with ammonia (ammonia SCR) and urea (urea SCR), respectively, is a widespread process to clean flue and diesel exhaust gases due to its simplicity and efficiency. The main challenge of the process is to minimize the ammonia emissions downstream of the SCR catalyst. We found that ammonia emissions of >10 ppm can reliably be detected with a simple pH electrode in the presence of CO2, SOx, NOx, and moderately weak organic acids. 10-20 ppm of ammonia in the exhaust gas are sufficient to neutralize the acids and to increase the pH value from 3 to 6. On this basis a continuous measuring method for ammonia was developed, which was used to control the dosage of urea in the SCR process. While keeping the ammonia emissions after the SCR catalyst at 5-30 ppm an average NOx removal efficiency (DeNOx) of >95% were achieved at a diesel test rig. The method can also be applied for exhaust gases with higher acid contents, if a basic pre-filter is added adsorbing the acidic exhaust components. Compared to water as absorption solution, more precise ammonia measurements are possible, if a 0.1 M NH4Cl absorption solution is applied, whose pH value is changing as a Nernst function of the ammonia concentration.

  8. 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.

  9. 铁铜双金属催化剂选择性催化氧化氨为氮气%Selective Catalytic Oxidation of Ammonia to Nitrogen over Iron and Copper Bimetallic Catalysts

    Institute of Scientific and Technical Information of China (English)

    孙萌萌; 曹毅; 兰丽; 邹莎; 房志涛; 陈耀强

    2014-01-01

    Iron and copper bimetal ic catalysts with fixed total contents of copper and iron were prepared by a co-impregnation method, and then used for selective catalytic oxidation of ammonia to nitrogen. The properties of the catalysts were characterized by N2 adsorption-desorption, H2 temperature-programmed reduction (H2-TPR), NH3 temperature-programmed desorption (NH3-TPD), X-ray diffraction (XRD), and X-ray photoelectron spectroscopy (XPS). The iron and copper bimetal ic catalysts exhibited good activity and high selectivity of N2 at the gas hourly space velocity (GHSV) of 100000 h-1. The activity and N2 selectivity in the low temperature range increased with increasing Cu loading, whereas in the high temperature range (above 400 ° C) the selectivity of N2 was directly related to the content of iron. The highest NH3 conversion was achieved at about 350 °C for Fe0.25Cu0.75/ZSM-5, and the N2 selectivity was up to 97%at 300 °C. On the other hand, the extremely high N2 selectivity about 98%was obtained over Fe0.75Cu0.25/ZSM-5 at 500 °C. In addition, N2O as the by-product and greenhouse gas was obtained in very low amounts for al the catalysts. The characterization results showed that the activity was influenced by the acid content and the amounts of copper species. Moreover, the highly reducing capacity could improve the N2 selectivity.%固定铜铁的总质量不变,采用共浸渍法制备铜铁双金属催化剂.为了更好地了解催化剂的性质,分别用N2吸附-脱附、H2-程序升温还原(H2-TPR)、NH3-程序升温脱附(NH3-TPD)、X射线衍射(XRD)和X射线光电子能谱(XPS)方法对制备的催化剂进行表征.研究发现在100000 h-1空速下,铜铁双金属催化剂呈现出好的活性和氮气选择性.在低温区,随着铜含量的增加,活性和氮气的选择性增加,然而在高温区氮气的选择性直接和铁的含量相关.其中催化剂Fe0.25Cu0.75/ZSM-5,在350° C氨的转化率达到最高,在300° C

  10. Investigation of Catalytic NOx, reduction with transient techniques, isotopic exchange and FT-IR spectroscopy

    International Nuclear Information System (INIS)

    Emissions from vehicles are suppressed by catalytic conversion, i.e. total oxidation of carbon monoxide and hydrocarbons and reduction of nitrogen oxides. The on-going demand for lower emissions requires more detailed knowledge about the catalytic reaction mechanisms and kinetics on the level of elementary steps, especially because of the mutual interactions in the complex reaction mixture. The reaction mechanisms for the abatement of nitrogen oxides (NOx) are of particular interest, since they are environmentally very unfriendly compounds. Transient experimental techniques can be used as a tool to understand the reaction mechanisms and to develop mathematical models allowing simulation and optimisation of the behaviour of three-way catalyst converters. In chemical kinetics, isotope-labelled reactants are frequently employed to follow reaction pathways and to determine reaction mechanisms. The kinetics and mechanisms of the catalytic reduction of nitrogen oxide (NO) by hydrogen as well as self-decomposition of NO and N2O were studied over alumina based palladium and rhodium-alumina monoliths. In addition, NO reduction with H2 and D2, isotope exchange of hydrogen atoms in water, ammonia and hydrogen with deuterium, as well as adsorption of ammonia and water on the Pd-monolith were studied with transient experiments. Transient step-response experiments, isotopic jumping techniques, steady- state isotopic-transient analysis, temperature programmed desorption (TPD) and Fourier-transformed infrared spectroscopy (FT-IR) were used as experimental techniques. The catalysts were characterised by carbon monoxide chemisorption, nitrogen physisorption and X-ray photoelectron spectroscopy (XPS). Nitrogen, nitrous oxide, ammonia, and water were detected as reaction products in NO reduction by hydrogen. The transient and FT-IR experiments yielded information about the surface reaction mechanisms. The dissociation of NO on the catalyst surface is the crucial step, dominating the

  11. 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...

  12. Experimental research on removing cyanide and ammonia nitrogen from industrial waste water produced by gold smelting with electro-catalytic oxidation process%电催化氧化法去除黄金冶炼废水中氰化物和氨氮试验研究

    Institute of Scientific and Technical Information of China (English)

    方荣茂; 廖小山; 廖斌; 林烽先; 刘亚建

    2013-01-01

    Research started with treating industrial waste water produced by gold smelting with electro-catalytic oxidation process, during which the influences of chloride ion mass concentration, plate clearance and current density on the removal of cyanide and ammonia nitrogen were analyzed. The result shows the optimal conditions for removing cyanide and ammonia nitrogen with electro-catalytic oxidation process are like this; the initial pH of waste water 9. 28, initial chloride ion concentration 25 g/L, plate clearance 20 mm, current density 16.3 mA/cm2 , and waste water circulation velocity 64 mL/min. With the above conditions and electrolysis time 150 min,the cyanide concentration decreases from 28. 84 mg/L to 0. 20 mg/L,and ammonia nitrogen from 700 mg/L to 7 mg/L. The removal rate is respectively 99. 3 % and 99. 0 %. The cyanide and ammonia nitrogen concentration remained in the treated water has reached of Grade 1 requirements of Integrated waste water discharge standard ( GB 8978 - 1996). The power consumption per ton water is 13.1 kw·h.%对黄金冶炼废水进行了电催化氧化处理研究,考察了氯离子质量浓度、极板间距、电流密度等因素对氰化物和氨氮去除效果的影响.最佳工艺参数为:废水初始pH值9.28、氯离子初始质量浓度25 g/L、极板间距20 mm、电流密度16.3 mA/cm2、废水循环流速64 mL/min.在最佳工艺条件下,电解150 min,氰化物质量浓度从28.84 mg/L降至0.20 mg/L,氨氮质量浓度从700 mg/L降至7 mg/L,去除率分别为99.3%、99.0%,处理后废水中的总氰、氨氮均可达到《GB 8978-1996污水综合排放标准》一级标准.

  13. Catalytic hot gas cleaning

    Energy Technology Data Exchange (ETDEWEB)

    Simell, P. [VTT Energy, Espoo (Finland)

    1996-12-31

    Gasification gas that contains particulates can be purified from tars and ammonia by using nickel monolith catalysts. Temperatures over 900 deg C are required at 20 bar pressure to avoid deactivation by H{sub 2}S and carbon. Dolomites and limestones are effective tar decomposing catalysts only when calcined. Tar decomposition in gasification conditions can take place by steam or dry (CO{sub 2}) reforming reactions. These reactions follow apparent first order kinetics with respect to hydrocarbons in gasification conditions. (author) (16 refs.)

  14. Unsteady catalytic processes and sorption-catalytic technologies

    International Nuclear Information System (INIS)

    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.

  15. 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.

  16. Development of catalytic gas cleaning in gasification

    Energy Technology Data Exchange (ETDEWEB)

    Simell, P.; Kurkela, E.; Staahlberg, P.; Hepola, J. [VTT Energy, Espoo (Finland)

    1996-12-31

    Gasification gas containing dust can be efficiently purified from tars and ammonia with a nickel monolith catalyst. Temperatures of >900 deg C and a residence time of about 1 s (SV 2 500 1/h) were needed at 5 bar pressure to achieve complete tar decomposition and 80 % ammonia conversion. Catalyst deactivation was not observed during test runs of 100 h. At lower pressures dolomites and limestones can also be applied for tar removal at about 900 deg C temperatures. (orig.) 12 refs.

  17. Composition decomposition

    DEFF Research Database (Denmark)

    Dyson, Mark

    2003-01-01

    . Not only have design tools changed character, but also the processes associated with them. Today, the composition of problems and their decomposition into parcels of information, calls for a new paradigm. This paradigm builds on the networking of agents and specialisations, and the paths of communication...

  18. Exhaust purification with on-board ammonia production

    Science.gov (United States)

    Robel, Wade J.; Driscoll, James Joshua; Coleman, Gerald N.

    2008-05-13

    A system of ammonia production for a selective catalytic reduction system is provided. The system includes producing an exhaust gas stream within a cylinder group, wherein the first exhaust gas stream includes NOx. The exhaust gas stream may be supplied to an exhaust passage and cooled to a predetermined temperature range, and at least a portion of the NOx within the exhaust gas stream may be converted into ammonia.

  19. Liquid composition having ammonia borane and decomposing to form hydrogen and liquid reaction product

    Science.gov (United States)

    Davis, Benjamin L; Rekken, Brian D

    2014-04-01

    Liquid compositions of ammonia borane and a suitably chosen amine borane material were prepared and subjected to conditions suitable for their thermal decomposition in a closed system that resulted in hydrogen and a liquid reaction product.

  20. Nickel ferrite spinel as catalyst precursor in the dry reforming of methane:Synthesis, characterization and catalytic properties

    Institute of Scientific and Technical Information of China (English)

    Rafik Benrabaa; Hamza Boukhlouf; Axel L(o)fberg; Annick Rubbens; Rose-N(o)elle Vannier; Elisabeth Bordes-Richard; Akila Barama

    2012-01-01

    Dry reforming of methane by CO2 using nickel ferrite as precursor of catalysts was investigated.Nickel ferrite crystalline particles were prepared by coprecipitation of nitrates with NaOH or ammonia followed by calcination,or by hydrothermal synthesis without calcination step.The textural and structural properties were determined by a number of analysis methods,including X-ray diffraction (XRD),Raman spectroscopy and X-ray photoelectron spectroscopy (XPS),among which X-ray diffraction (XRD) was at room and variable temperatures.All synthesized oxides showed the presence of micro or nanoparticles of NiFe2O4 inverse spinel,but Fe2O3 (hematite) was also present when ammonia was used for coprecipitation.The reducibility by hydrogen was studied by temperature-programmed reduction (TPR) and in situ XRD,which showed the influence of the preparation method.The surface area (BET),particle size (Rietveld refinement),as well as surface Ni/Fe atomic ratio (XPS) and the behavior upon reduction varied according to the synthesis method.The catalytic reactivity was investigated using isopropanol decomposition to determine the acid/base properties.The catalytic performance of methane reforming with CO2 was measured with and without the pre-treatment of catalysts under H2 in 650-800 ℃ range.The catalytic conversions of methane and CO2 were quite low but they increased when the catalysts were pre-reduced.A significant contribution of reverse water gas shift reaction accounted for the low values of H2/CO ratio.No coking was observed as shown by the reoxidation step performed after the catalytic reactions.The possible formation of nickel-iron alloy observed during the study of reducibility by hydrogen was invoked to account for the catalytic behavior.

  1. 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.

  2. 纳米SiO2负载的过渡金属硼化物对AP热分解的催化作用%Catalytic Activity of Nano-silica Supported Transition-metal Borides on the Thermal Decomposition of Ammonium Perchlorate

    Institute of Scientific and Technical Information of China (English)

    李茸; 刘祥萱; 王煊军

    2012-01-01

    采用化学还原法制备纳米NiB/SiO2、CoB/SiO2、MoB/SiO2催化剂,通过热重-差热分析(TG-DTA)研究了其对AP热分解过程的催化作用.结果表明,负载过渡金属硼化物催化剂对AP分解的催化活性顺序为:CoB/SiO2>NiB/SiO2> MoB/SiO2;加入质量分数5%的CoB/SiO2使AP高温热分解峰温度降低166.2℃;SiO2载体将CoB晶型转化推迟了 110℃左右,改善了催化剂的热稳定性.%The nano-silica supported transition metal catalysts NiB/SiO2 , CoB/SiO2 , MoB/SiO2 were prepared by chemical reduction method. Their catalytic activity on the thermal decomposition of ammonium perchlorate (AP) was studied by TG-DTA. Results show that catalytic activity of nano-silica supported transition metal borides for the thermal decomposition of AP decreases in the order: CoB/SiO2 > NiB/SiO2 >MoB/SiO2. The CoB/SiO2 (mass ration of 5%) catalyst makes the high-temperature thermal decomposition temperature of AP decrease by 166. 2℃. The SiO2 carrier makes the crystal transformation temperature delay about 110℃, revealling the improvement of thermal stability of the catalyst.

  3. Cobalt-Nickel-Boron Supported over Polypyrrole-Derived Activated Carbon for Hydrolysis of Ammonia Borane

    Directory of Open Access Journals (Sweden)

    Yongjin Zou

    2016-07-01

    Full Text Available In this study, polypyrrole (PPy nanofibers were used to synthesize a super-activated carbon material. A highly-dispersed Co-Ni-B catalyst was supported on PPy nanofiber-derived activated carbon (PAC by chemical reduction. The Co-Ni-B/PAC hybrid catalyst exhibited excellent catalytic performance for the decomposition of ammonia borane (AB in an aqueous alkaline solution at room temperature. The size of the metal particles, morphology of Co-Ni-B/PAC, and catalytic activity of the supported catalyst were investigated. Ni-B, Co-B, and Co-Ni-B catalysts were also synthesized in the absence of PAC under similar conditions for comparison. The maximum hydrogen generation rate (1451.2 mL−1·min−1·g−1 at 25 °C was obtained with Co-Ni-B/PAC. Kinetic studies indicated that the hydrolysis reaction of AB was first order with respect to Co-Ni-B/PAC, and the activation energy was 30.2 kJ·mol−1. Even after ten recycling experiments, the catalyst showed good stability owing to the synergistic effect of Co-Ni-B and PAC.

  4. Influences of ammonia contamination on leaching from air-pollution-control residues

    DEFF Research Database (Denmark)

    Guan, Zhenzhen; Chen, Dezhen; Astrup, Thomas Fruergaard

    2014-01-01

    Application of selective non-catalytic reduction systems at municipal solid waste incinerators (MSWIs) often involves over-stoichiometric injection of ammonia into flue gases. Un-reacted ammonia may be deposited on fly ash particles and can ultimately influence the leaching behaviour of air-pollution...

  5. Influence of ammonia on leaching behaviors of incineration fly ash and its geochemical modeling

    DEFF Research Database (Denmark)

    Astrup, Thomas Fruergaard; Guan, Zhen Zhen; Chen, De Zhen

    2013-01-01

    Incineration fly ash could be contaminated with NH3 that was slipped from the ammonia-based selective non-catalytic reduction(SNCR) process and from evaporation of municipal solid wastes' leachate involved in the wastes. This research was conducted to investigate the impacts of ammonia on leaching...

  6. Surface modification of multi-walled carbon nanotubes by ammonia and catalytic degradation of oxalic acid by ozonation%多壁碳纳米管的氨表面改性及其臭氧催化降解草酸

    Institute of Scientific and Technical Information of China (English)

    何志桥; 姜哲; 姜理英; 杨樟保; 陈建孟; 宋爽

    2012-01-01

    采用水热方法制备了一系列用浓氨水改性的多壁碳纳米管催化剂,该催化剂的活性通过非均相催化臭氧化降解水溶液中的草酸来进行评价.降解过程符合零级反应动力学模型,且催化剂的表观动力学常数与其表面碱性基团数量以及零电位pH值(pHpzc)呈正相关.为此,可断定用浓氨在水热条件下处理多壁碳纳米管能明显提高催化臭氧降解草酸能力是因为提高了催化剂的表面碱性基团数量和pHpzc.%A series of ammonia-modified multi-walled carbon nanotubes was prepared via hydrothermal method. Their catalytic activity was evaluated by oxalic acid degradation in aqueous solution in the presence of ozone. It was found that the reaction process can be fitted to zero-order reaction kinetics. The apparent zero-order rate constant had a positive relation with the basic groups and pH value at zero charge point (pHpzc) of the catalysts. On this basis, it can be concluded that the significant enhancement of oxalic acid degradation is achieved by hydrothermal treatment with ammonia. The reason could be that the method promotes formation of basic groups and increase of pHPZC.

  7. Assessing Ammonia Treatment Options

    Science.gov (United States)

    This is the second of three articles to help water system operators understand ammonia and how to monitor and control its effects at the plant and in the distribution system. The first article (Opflow, April 2012) provided an overview of ammonia's chemistry, origins, and water sy...

  8. Method for forming ammonia

    Science.gov (United States)

    Kong, Peter C.; Pink, Robert J.; Zuck, Larry D.

    2008-08-19

    A method for forming ammonia is disclosed and which includes the steps of forming a plasma; providing a source of metal particles, and supplying the metal particles to the plasma to form metal nitride particles; and providing a substance, and reacting the metal nitride particles with the substance to produce ammonia, and an oxide byproduct.

  9. Ammonia sensor for closed-loop SCR control

    NARCIS (Netherlands)

    Wang, D.Y.; Yao, S.; Shost, M.; Yoo, J.H.; Cabush, D.; Racine, D.; Cloudt, R.P.M.; Willems, F.P.T.

    2009-01-01

    Selective Catalytic Reduction (SCR) is the dominant solution for meeting future NOx reduction regulations for heavy-duty diesel powertrains. SCR systems benefit from closed-loop control if an appropriate exhaust gas sensor were available. An ammonia sensor has recently been developed for use as a fe

  10. 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.

  11. Predicting catalysis: Understanding ammonia synthesis from first-principles calculations

    DEFF Research Database (Denmark)

    Hellmann, A.; Baerends, E.J.; Biczysko, M.;

    2006-01-01

    Here, we give a full account of a large collaborative effort toward an atomic-scale understanding of modern industrial ammonia production over ruthenium catalysts. We show that overall rates of ammonia production can be determined by applying various levels of theory (including transition state...... for any given point along an industrial reactor, and the kinetic results can be integrated over the catalyst bed to determine the industrial reactor yield. We find that, given the present uncertainties, the rate of ammonia production is well-determined directly from our atomic-scale calculations....... Furthermore, our studies provide new insight into several related fields, for instance, gas-phase and electrochemical ammonia synthesis. The success of predicting the outcome of a catalytic reaction from first-principles calculations supports our point of view that, in the future, theory will be a fully...

  12. 不同MgO担体对Ba-Ru/MgO氨合成催化剂物化性质和反应性能的影响%Effect of Different Supports on Physical and Chemical Properties and Catalytic Activity over Ba-Ru/MgO Ammonia Synthesis Catalysts

    Institute of Scientific and Technical Information of China (English)

    杨晓龙; 唐立平; 夏春谷; 熊绪茂; 慕新元; 胡斌

    2012-01-01

    MgO supports were prepared by different precipitants and further examined as the supports for barium-promoted ruthenium catalyst for ammonia synthesis.The reason resulting in their difference of catalytic activity were explored by X-ray diffraction,N2 adsorption-desorption,X-ray fluorescence spectroscopy,transmission electron microscopy,H2 temperature-programmed reduction,CO2 temperature-programmed desorption,H2 temperature-programmed desorption and N2 temperature-programmed desorption.It was found that MgO prepared by(NH4)2CO3 precipitant facilitated the reduction of ruthenium oxide for Ba-Ru/MgO catalyst,and the weak basic sites of Ba-Ru/MgO((NH4)2CO3 as precipitant) appeared at lower temperature and showed higher weak basic site densities compared with the others.At 450 ℃、 5.0 MPa and 5 000 h-1,catalytic activity of Ba-Ru/MgO catalyst employing(NH4)2CO3 as the precipitant was higher than that of the catalyst prepared by other precipitants under the same reaction conditions,the ammonia concentration in the effluent reached 3.74%.The addition of Ba promoter significantly decreased the amount of hydrogen chemisorption,increased the number of dissociatively adsorbed N* on the Ru surface and thus accelerated the reaction rate of ammonia synthesis.%采用不同沉淀剂制备了MgO材料,以其为载体制备了Ba-Ru/MgO氨合成催化剂,考察了沉淀剂种类和BaO助剂对其氨合成性能的影响.通过X射线衍射(XRD)、N2物理吸附、X射线荧光光谱(XRF)、透射电镜(TEM)、H2程序升温还原(H2-TPR)、CO2程序升温脱附(CO2-TPD)、H2程序升温脱附(H2-TPD)和N2程序升温脱附(N2-TPD)表征手段,对不同沉淀剂影响Ba-Ru/MgO催化剂氨合成性能的原因进行了探索.结果表明:采用(NH4)2CO3作沉淀剂制备的Ba-Ru/MgO催化剂表面Ru物种易于在低温下还原,催化剂表面在低温区具有较多数量的弱碱性吸附位,在450℃、5.0 MPa和5 000 h-1

  13. System and method for determining an ammonia generation rate in a three-way catalyst

    Science.gov (United States)

    Sun, Min; Perry, Kevin L; Kim, Chang H

    2014-12-30

    A system according to the principles of the present disclosure includes a rate determination module, a storage level determination module, and an air/fuel ratio control module. The rate determination module determines an ammonia generation rate in a three-way catalyst based on a reaction efficiency and a reactant level. The storage level determination module determines an ammonia storage level in a selective catalytic reduction (SCR) catalyst positioned downstream from the three-way catalyst based on the ammonia generation rate. The air/fuel ratio control module controls an air/fuel ratio of an engine based on the ammonia storage level.

  14. Reactor for removing ammonia

    Science.gov (United States)

    Luo, Weifang; Stewart, Kenneth D.

    2009-11-17

    Disclosed is a device for removing trace amounts of ammonia from a stream of gas, particularly hydrogen gas, prepared by a reformation apparatus. The apparatus is used to prevent PEM "poisoning" in a fuel cell receiving the incoming hydrogen stream.

  15. Ammonia Clouds on Jupiter

    Science.gov (United States)

    2007-01-01

    [figure removed for brevity, see original site] Click on the image for movie of Ammonia Ice Clouds on Jupiter In this movie, put together from false-color images taken by the New Horizons Ralph instrument as the spacecraft flew past Jupiter in early 2007, show ammonia clouds (appearing as bright blue areas) as they form and disperse over five successive Jupiter 'days.' Scientists noted how the larger cloud travels along with a small, local deep hole.

  16. 微波辅助苯乙基苯醚催化降解反应动力学%Kinetics study on microwave-assisted catalytic decomposition of phenylethyl phenyl ether

    Institute of Scientific and Technical Information of China (English)

    潘晶莹; 熊俊; 吕秀阳

    2013-01-01

    Employing phenylethyl phenyl ether (PPE) as a lignin model compound,tetralin as a solvent and hydrogen-donor,toluene-4-sulfonic acid (PTSA) as a catalyst,the regularity of decomposition of PPE was studied with the microwave and tetralin.The effect of microwave to the reaction was discussed and a possible mechanism on the degradation with the microwave and tetralin was presented.The HPLC results indicated that the conversion of PPE decreased with the increase of initial mass density of PPE and was improved with the increase of mass density of PSTA.Compared to reactions with traditional heat conduction,microwave irradiation promoted the decomposition reaction of PPE significantly,and the apparent activation energy for PPE decomposition with microwave decreased by 27.7%.%以苯乙基苯醚(PPE)为木质素模型物质,四氢萘为溶剂和供氢剂,对甲苯磺酸(PTSA)为催化剂,研究PPE在微波和四氢萘作用下的降解规律,总结了微波对降解反应的影响并推断PPE在四氢萘和PTSA作用下的降解机理.高效液相识谱法的分析结果表明:随着PPE初始质量密度的升高,PPE的转化率有所下降;随着PTSA质量密度的升高,PPE的转化率也不断升高.相对于普通的热传导加热,微波对PPE的催化降解反应起到了比较明显的促进作用,降解反应的表观活化能下降了27.7%.

  17. Ammonia-Free NOx Control System

    Energy Technology Data Exchange (ETDEWEB)

    S. Wu

    2003-12-31

    Research is being conducted under United States Department of Energy (DOE) Contract DEFC26-03NT41865 to develop a new technology to achieve very low levels of NOx emissions from pulverized coal fired boiler systems by employing a novel system level integration between the PC combustion process and the catalytic NOx reduction with CO present in the combustion flue gas. The combustor design and operating conditions will be optimized to achieve atypical flue gas conditions. This approach will not only suppress NOx generation during combustion but also further reduce NOx over a downstream catalytic reactor that does not require addition of an external reductant, such as ammonia. This report describes the work performed during the October 1 to December 31, 2003 time period.

  18. Ammonia-Free NOx Control System

    Energy Technology Data Exchange (ETDEWEB)

    Song Wu; Zhen Fan; Andrew H. Seltzer; Richard G. Herman

    2004-09-30

    Research is being conducted under United States Department of Energy (DOE) Contract DEFC26-03NT41865 to develop a new technology to achieve very low levels of NOx emissions from pulverized coal fired boiler systems by employing a novel system level integration between the PC combustion process and the catalytic NOx reduction with CO present in the combustion flue gas. The combustor design and operating conditions will be optimized to achieve atypical flue gas conditions. This approach will not only suppress NOx generation during combustion but also further reduce NOx over a downstream catalytic reactor that does not require addition of an external reductant, such as ammonia. This report describes the work performed during the July 1 to September 30, 2004 time period.

  19. Ammonia-Free NOx Control System

    Energy Technology Data Exchange (ETDEWEB)

    S. Wu; Z. Fan; R. Herman

    2004-03-31

    Research is being conducted under United States Department of Energy (DOE) Contract DEFC26-03NT41865 to develop a new technology to achieve very low levels of NOx emissions from pulverized coal fired boiler systems by employing a novel system level integration between the PC combustion process and the catalytic NOx reduction with CO present in the combustion flue gas. The combustor design and operating conditions will be optimized to achieve atypical flue gas conditions. This approach will not only suppress NOx generation during combustion but also further reduce NOx over a downstream catalytic reactor that does not require addition of an external reductant, such as ammonia. This report describes the work performed during the January 1 to March 31, 2004 time period.

  20. Effect of Zr{sup 4+} doping on the stabilization of ZnCo-mixed oxide spinel system and its catalytic activity towards N{sub 2}O decomposition

    Energy Technology Data Exchange (ETDEWEB)

    Basahel, S.N.; El-Maksod, I.H. Abd [Chemistry Department, Faculty of Science, King Abdulaziz University, Jeddah 21569 (Saudi Arabia); Abu-Zied, B.M. [Chemistry Department, Faculty of Science, Assiut University, Assiut 71516 (Egypt); Mokhtar, M., E-mail: mmokhtar2000@yahoo.co [Chemistry Department, Faculty of Science, King Abdulaziz University, Jeddah 21569 (Saudi Arabia)

    2010-03-18

    Cobalt-zinc hydroxycarbonate precursor with nominal Co/Zn atomic ratio of 2 and 0.05-0.15 mol% ZrO{sub 2}-doped precursors have been synthesized from their metal nitrate and sodium carbonate by coprecipitation route. ZnCo{sub 2}O{sub 4} spinel oxide was formed during the precipitation process as complemented by FTIR. Decomposition of the Co/Zn precursor at 350 {sup o}C resulted in the formation of ZnCo{sub 2}O{sub 4} as evidenced by XRD technique. Zr{sup 4+}-doped samples stabilized the ZnCo{sub 2}O{sub 4} phase and suppressed the formation of ZnO phase at 550 and 750 {sup o}C. The highest surface areas (S{sub BET}) were attained for the samples doped with 0.15 mol% ZrO{sub 2}. Activation energy of sintering derived from XRD and S{sub BET} data was directly proportional to the dopant concentration. ESR results revealed that the addition of increased amounts of Zr{sup 4+} enhances the formation of Co{sup 2+} ions. The activity of the 350 and 750 {sup o}C calcined catalysts was tested for N{sub 2}O direct decomposition. The observed activities were related to the presence of Co{sup 2+}-Co{sup 3+} ion pairs which were enhanced by the addition of Zr{sup 4+} ions.

  1. Characterization and catalytic behavior of MoO{sub 3}/V{sub 2}O{sub 5}/Nb{sub 2} O{sub 5} systems in isopropanol decomposition

    Energy Technology Data Exchange (ETDEWEB)

    Paiva Junior, J.B. de; Cortez, G.G. [Universidade de Sao Paulo, Lorena, SP (Brazil). Escola de Engenharia. Lab. de Catalise II]. E-mail: cortez@dequi.faenquil.br; Monteiro, W.R.; Zacharias, M.A.; Rodrigues, J.A.J. [Instituto Nacional de Pesquisas Espaciais (INPE), Sao Jose dos Campos, SP (Brazil). Lab. Associado de Combustao e Propulsao]. E-mail: jajr@lcp.inpe.br

    2006-10-15

    The influence of molybdenum oxide as a promoter on the V{sub 2}O{sub 5}/Nb{sub 2}O{sub 5} system was investigated. A series of MoO{sub 3}/V{sub 2}O{sub 5}/Nb{sub 2}O{sub 5} catalysts, with MoO{sub 3} loading ranging from 1 to 3 wt% MoO{sub 3} and fixed V{sub 2}O{sub 5} content (21 wt%), were prepared by impregnation of the Nb{sub 2}O{sub 5} 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,V){sub 2}O{sub 5} 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 V{sub 2}O{sub 5}/Nb{sub 2}O{sub 5} catalysts are affected upon incorporation of MoO{sub 3}, specifically for loadings of 3 wt %. For this catalyst composition both propylene and acetone formation rates decreased. (author)

  2. Preparation of graphite-like carbon nitride and its catalytic performance for thermal decomposition of ammonium perchlorate%类石墨型氮化碳的制备及其对AP热分解催化性能研究∗

    Institute of Scientific and Technical Information of China (English)

    谈玲华; 杭祖圣; 寇波; 徐建华; 郏永强; 王善斌

    2015-01-01

    The g-C3 N4 was synthesized melamine used as precursor via semi-closed method.The structure and morphology of g-C3 N4 were characterized by means of X-ray diffraction(XRD),transmission electron microsco-py(SEM)and Fourier transform infrared spectroscopy(FT-IR).The catalysis of g-C3 N4 on thermal decomposi-tion of ammonium perchlorate(AP)was investigated bythermal gravimetric analysis (TG)and differential ther-mal analysis (DTA).The results show that the g-C3 N4 has layered structure.The g-C3 N4 make the two decom-position peaks of AP combine and the high-temperature decomposition peak value of AP decrease by 73.8 ℃, which exhibits good catalytic performance.The g-C3 N4 has excellent conductive properties and can accelerate the electron transfer in the process of oxidation-reduction cycle to make the decomposition of AP at a much lower temperature.%以三聚氰胺为前驱体、半封闭法制备出类石墨型氮化碳(g-C3 N4),采用 X 射线衍射(XRD)、扫描电子显微镜(SEM)、傅里叶红外光谱(FT-IR)对其结构和形貌进行表征,利用热失重(TG )、差热分析(DTA)研究g-C3 N4对高氯酸铵(AP)热分解的影响.结果表明,制备出的 g-C3 N4为层状结构. g-C3 N4对AP有较强的催化效果,可使 AP 的高低温分解峰合并,高温分解温度下降73.8℃.g-C3 N4优异的导电性能,在氧化还原循环中能加速电子转移,使 AP 在更低的温度下分解.

  3. Lanthanum-Promoted Ru/Sepiolite in Ammonia Synthesis

    Institute of Scientific and Technical Information of China (English)

    Le Zhiping; Lin Jianxin; Yu Xiujin; Huang Yueyu; Wei Kemei

    2005-01-01

    A new kind of Ru supported on sepiolite catalyst with La as promoter for ammonia synthesis was prepared. The effects of reaction conditions on catalytic activity were discussed. The result shows that La is an effective promoter for sepiolite-supported Ru based catalyst. When the load of Ru is 5% (mass fraction), and the molar ratio of La/Ru is 1.5, under the condition of 10 MPa 450 ℃ 20000 h-1, the ammonia synthesis rate is 38.5 mmol NH3·g-1·h-1.

  4. Structural properties of cyanase. Denaturation, renaturation, and role of sulfhydryls and oligomeric structure in catalytic activity.

    Science.gov (United States)

    Little, R M; Anderson, P M

    1987-07-25

    Cyanase is an inducible enzyme in Escherichia coli that catalyzes bicarbonate-dependent decomposition of cyanate to give ammonia and bicarbonate. The enzyme is composed of 8-10 identical subunits (Mr = 17,008). The objective of this study was to clarify some of the structural properties of cyanase for the purpose of understanding the relationship between oligomeric structure and catalytic activity. Circular dichroism studies showed that cyanase has a significant amount of alpha-helix and beta-sheet structure. The one sulfhydryl group per subunit does not react with 5,5'-dithiobis-(2-nitrobenzoic acid) (DTNB) unless cyanase is denatured. Denaturation is apparently complete in 10 M urea or 6 M guanidine hydrochloride, but is significantly reduced in 10 M urea by the presence of azide (analog of cyanate) and is incomplete in 8 M urea. Denatured cyanase could be renatured and reactivated (greater than 85%) by removal of denaturants. Reactivation was greatly facilitated by the presence of certain anions, particularly bicarbonate, and by high ionic strength and protein concentration. The catalytic activity of renatured cyanase was associated only with oligomer. Cyanase that had been denatured in the presence of DTNB to give a cyanase-DTNB derivative could also be renatured at 26 degrees C to give active cyanase-DTNB oligomer. The active oligomeric form of the cyanase-DTNB derivative could be converted reversibly to inactive dimer by lowering the temperature to 4 degrees C or by reduction of the ionic strength and removal of monoanions. These results provide evidence that free sulfhydryl groups are not required for catalytic activity and that catalytic activity may be dependent upon oligomeric structure.

  5. 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.

  6. Cu、Co交换改性蒙脱土的制备及其对N2O分解的催化活性%PREPARATION OF Cu,Co-EXCHANGED Al-PILLARED MONTMORILLONITE AND ITS CATALYTIC ACTIVITY FOR N2O DECOMPOSITION

    Institute of Scientific and Technical Information of China (English)

    徐秀峰; 索掌怀; 魏玉萍; 宫宝安; 安立敦

    2001-01-01

    用Al交联剂对天然蒙脱土改性,制得Al交联(支撑)蒙脱土。用Cu2+、Co2+离子交换蒙脱土层间阳离子,制备Cu、Co交换蒙脱土,经高温焙烧,得到实验用催化剂,考察它们对N2O分解的催化活性。结果表明:用Al/土比为10 mmol/g的Al交联蒙脱土作载体,通过优化制备条件制得的Cu交换蒙脱土,催化活性与CuY 相近;而Co-蒙脱土的催化活性甚至高于 CoY。%Nitrous oxide(N2O) is now considered as a greenhouse gas and contributes to catalytic stratospheric-ozone destruction. Therefore, the catalytic decomposition of N2O has become one of the urgent environmental issues. In this paper, raw montmorillonite was pillared by oligomeric hydroxyl aluminum cation with changing Al/clay ratio to make Al cross-linked montmorillonite (Al-CLM). The basal spacing(d001) of Al-CLM measured by X-ray diffraction is 1.80?nm, while that of raw montmorillonite 1.53?nm. The thermal stability of modified CLM was improved by Al pillar. Cu, Co-exchanged Al-CLM catalysts were prepared by changing preparation parameters and used to catalytically decompose N2O. The results show that the catalytic activity of Cu-exchanged clay with Al/clay ratio 10 mmol/g, calcined at 500 ℃, is equivalent to that of CuY, while Co-clay even higher than CoY for 3% N2O and 1% CH4 feed gas at space velocity 5000 h-1.

  7. Respiratory ammonia output and blood ammonia concentration during incremental exercise

    NARCIS (Netherlands)

    Ament, W; Huizenga, [No Value; Kort, E; van der Mark, TW; Grevink, RG; Verkerke, GJ

    1999-01-01

    The aim of this study was to investigate whether the increase of ammonia concentration and lactate concentration in blood was accompanied by an increased expiration of ammonia during graded exercise. Eleven healthy subjects performed an incremental cycle ergometer test. Blood ammonia, blood lactate

  8. Ammonia volatilization from crop residues and frozen green manure crops

    Science.gov (United States)

    de Ruijter, F. J.; Huijsmans, J. F. M.; Rutgers, B.

    2010-09-01

    Agricultural systems can lose substantial amounts of nitrogen (N). To protect the environment, the European Union (EU) has adopted several directives that set goals to limit N losses. National Emission Ceilings (NEC) are prescribed in the NEC directive for nitrogen oxides and ammonia. Crop residues may contribute to ammonia volatilization, but sufficient information on their contribution to the national ammonia volatilization is lacking. Experiments were carried out with the aim to assess the ammonia volatilization of crop residues left on the soil surface or incorporated into the soil under the conditions met in practice in the Netherlands during late autumn and winter. Ammonia emission from residues of broccoli, leek, sugar beet, cut grass, fodder radish (fresh and frozen) and yellow mustard (frozen) was studied during two winter seasons using volatilization chambers. Residues were either placed on top of soil or mixed with soil. Mixing residues with soil gave insignificant ammonia volatilization, whereas volatilization was 5-16 percent of the N content of residues when placed on top of soil. Ammonia volatilization started after at least 4 days. Total ammonia volatilization was related to C/N-ratio and N concentration of the plant material. After 37 days, cumulative ammonia volatilization was negligible from plant material with N concentration below 2 percent, and was 10 percent of the N content of plant material with 4 percent N. These observations can be explained by decomposition of plant material by micro-organisms. After an initial built up of the microbial population, NH 4+ that is not needed for their own growth is released and can easily emit as NH 3 at the soil surface. The results of the experiments were used to estimate the contribution of crop residues to ammonia volatilization in the Netherlands. Crop residues of arable crops and residues of pasture topping may contribute more than 3 million kg NH 3-N to the national ammonia volatilization of the

  9. AMMONIA-FREE NOx CONTROL SYSTEM

    Energy Technology Data Exchange (ETDEWEB)

    Song Wu; Zhen Fan; Andrew H. Seltzer; Richard G. Herman

    2006-06-01

    This report describes a novel NOx control system that has the potential to drastically reduce cost, and enhance performance, operation and safety of power plant NOx control. The new system optimizes the burner and the furnace to achieve very low NOx levels and to provide an adequate amount of CO, and uses the CO for reducing NO both in-furnace and over a downstream AFSCR (ammonia-free selective catalytic reduction) reactor. The AF-SCR combines the advantages of the highly successful SCR technology for power plants and the TWC (three-way catalytic converter) widely used on automobiles. Like the SCR, it works in oxidizing environment of combustion flue gas and uses only base metal catalysts. Like the TWC, the AF-SCR removes NO and excess CO simultaneously without using any external reagent, such as ammonia. This new process has been studied in a development program jointed funded by the US Department of Energy and Foster Wheeler. The report outlines the experimental catalyst work performed on a bench-scale reactor, including test procedure, operating conditions, and results of various catalyst formulations. Several candidate catalysts, prepared with readily available transition metal oxides and common substrate materials, have shown over 80-90% removal for both NO and CO in oxidizing gas mixtures and at elevated temperatures. A detailed combustion study of a 400 MWe coal-fired boiler, applying computational fluid dynamics techniques to model boiler and burner design, has been carried out to investigate ways to optimize the combustion process for the lowest NOx formation and optimum CO/NO ratios. Results of this boiler and burner optimization work are reported. The paper further discusses catalyst scale-up considerations and the conceptual design of a 400 MWe size AF-SCR reactor, as well as economics analysis indicating large cost savings of the ammonia-free NOx control process over the current SCR technology.

  10. Liberation of ammonia by cyanobacteria

    International Nuclear Information System (INIS)

    Photoheterotrophic nitrogen-fixing cyanobacteria release ammonia when treated with methionine sulfoximine (MSX) to inhibit nitrogen incorporation into protein. This released ammonia can be derived from recently fixed nitrogen (nitrogen atmosphere) or endogenous reserves (argon atmosphere). Anaerobic ammonia release requires light and is stimulated by the photosystem II herbicides DCMU and Atrazine, regardless of the source of ammonia. As much as one quarter of the total cellular nitrogen can be released as ammonia by cyanbacteria treated with MSX and DCMU under argon in light. Chromatography of cell extracts indicates that virtually all cellular proteins are degraded. DCMU and Atrazine, at very low concentration, inhibit sustained uptake of the ammonia analog 14C methylamine. These data indicate that the herbicides interrupt ammonia uptake and retention by the cells, and support a role for photosystem II in ammonia metabolism

  11. Preparation of nanometer FeCuP alloy and its application in decomposition of PH3

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    A new ternary Fe-based alloy catalyst FeCuP applied to decompose PH3 was prepared with low-cost material by chemical reduction deposition method. The properties of it were characterized by XRD, ICP and SEM. Its catalytic activity on the decomposition of PH3 and the decomposition conditions were studied. FeCuP alloy exhibits high thermal stabilities and high catalytic activity. Using it as catalyst, the decomposition temperature of phosphine decreases from over 800 ℃ to 400-500 ℃. The decomposition rate of phosphine achieved 100%.

  12. Enhancement of Alkene Epoxidation Activity of Titanosilicates by Gas-Phase Ammonia Modification

    Institute of Scientific and Technical Information of China (English)

    张里艳; 徐乐; 孙晶晶; 蒋金刚; 刘月明; 吴海虹; 吴鹏

    2012-01-01

    Novel ammonia-treated titanosilicates have been prepared by heating the samples of Ti-MWW, TS-l and Ti-Beta under pure ammonia gas flow at 673 K for a period of time. The ammonia modification improved their catalytic performance in liquid-phase oxidations. Especially, the catalytic activities of ammonified Ti-MWW, N-Ti-MWW, were enhanced greatly in the epoxidation of 1-hexene with H2O2. The reason that the ammonia treat- ment played such an important role in post-modification of titanosilicate was investigated in details. In comparison to the parent Ti-MWW catalyst, N-Ti-MMW was more robust and produced less coke in oxidation reactions.

  13. Experimental and modelling evaluation of an ammonia-fuelled microchannel reactor for hydrogen generation / Steven Chiuta

    OpenAIRE

    Chiuta, Steven

    2015-01-01

    In this thesis, ammonia (NH3) decomposition was assessed as a fuel processing technology for producing on-demand hydrogen (H2) for portable and distributed fuel cell applications. This study was motivated by the present lack of infrastructure to generate H2 for proton exchange membrane (PEM) fuel cells. An overview of past and recent worldwide research activities in the development of reactor technologies for portable and distributed hydrogen generation via NH3 decomposition wa...

  14. Heterogeneous Catalytic Ozonization of Sulfosalicylic Acid

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    This paper describes the potential of heterogeneous catalytic ozonization of sulfo-salicylic acid (SSal). It was found that catalytic ozonization in the presence of Mn-Zr-O (a modified manganese dioxide supported on silica gel) had significantly enhanced the removal rate (72%) of total organic carbon (TOC) compared with that of ozonization alone (19%). The efficient removal rate of TOC was probably due to increasing the adsorption ability of catalyst and accelerating decomposition of ozone to produce more powerful oxidants than ozone.

  15. Spectral Decomposition Algorithm (SDA)

    Data.gov (United States)

    National Aeronautics and Space Administration — Spectral Decomposition Algorithm (SDA) is an unsupervised feature extraction technique similar to PCA that was developed to better distinguish spectral features in...

  16. Copper Containing SBA-15 Prepared through pH Modification Method and Its Catalytic Activity for N_2 O Decomposition%铜掺杂SBA-15的pH调节法直接合成及其在N_2O分解反应中的催化性能

    Institute of Scientific and Technical Information of China (English)

    Mohd Haizal Mohd Husin; Mohd Ridzuan Nordin; 李金林; 刘光荣; Chin Sim Yee

    2012-01-01

    Copper-substituted SBA-15(Cu/SBA-15) mesoporous materials were directly synthesized under acidic conditions by a "pH modification method" using hexamethylenetetramine(HMTA) as an internal pH-modifier.The synthesized material has been characterized by XRD,SEM-EDX,TEM and FT-IR.The results showed that the resultant materials exhibit highly ordered hexagonal mesoporous structures.In addition,the HMTA also strongly affected the incorporation of copper in the silica framework.During hydrothermal process the HMTA dissociates to release NH3 and increases the internal pH value and helps to introduce more copper into SBA-15 framework.Catalytic screenings reveal that Cu/SBA-15 materials can be used as potential catalyst for the decomposition of N2O.The Cu/SBA-15(110) have good catalytic activity causing 50% of N2O to decomposed at 600°C.%酸性条件下,用环六亚甲基四胺作为pH调节剂,采用pH调节法直接合成了铜同构替代掺杂的SBA-15中孔分子筛(Cu/SBA-15).采用X-射线衍射(XRD)、扫描电子显微镜-能量色散X射线光谱(SEM-EDX)、透射电子显微镜(TEM)以及傅立叶变换红外光谱(FT-IR)等技术对目标材料进行了表征.结果表明:该材料具有六方中孔有序结构,且环六亚甲基四胺显著影响了铜和SBA-15硅骨架的结合,在水热合成过程中,环六亚甲基四胺分解释放出氨气,增加了体系的pH值,有助于更多的铜进入到分子筛的骨架中.该材料可用于N2O分解反应的催化剂,其中Cu/SBA-15(110)在600℃下具有优异的催化活性,可分解50%N2O.

  17. A DECOMPOSITION METHOD OF STRUCTURAL DECOMPOSITION ANALYSIS

    Institute of Scientific and Technical Information of China (English)

    LI Jinghua

    2005-01-01

    Over the past two decades,structural decomposition analysis(SDA)has developed into a major analytical tool in the field of input-output(IO)techniques,but the method was found to suffer from one or more of the following problems.The decomposition forms,which are used to measure the contribution of a specific determinant,are not unique due to the existence of a multitude of equivalent forms,irrational due to the weights of different determinants not matching,inexact due to the existence of large interaction terms.In this paper,a decomposition method is derived to overcome these deficiencies,and we prove that the result of this approach is equal to the Shapley value in cooperative games,and so some properties of the method are obtained.Beyond that,the two approaches that have been used predominantly in the literature have been proved to be the approximate solutions of the method.

  18. Ammonia emissions in Europe

    DEFF Research Database (Denmark)

    Jacobsen, Brian H.

    2012-01-01

    The NEC (National Emission Ceiling) directive has set targets for the 2010 ammonia emissions from a number of European countries. The target will be reached by most EU-countries and the total emission for EU-27 has been reduced by 22% from 1990 to 2007. Denmark is one of the countries...... technology is adopted quicker and that the farm has the right location. It is concluded that the new application process so far has not lived up to the high expectations at the outset. Despite this, the paper concludes that Denmark is likely to reduce emission by 50% from 1990 to 2020 and reach the likely...

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

    Institute of Scientific and Technical Information of China (English)

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

    2003-01-01

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

  20. Theoretical models for NO decomposition in Cu-exchanged zeolites

    CERN Document Server

    Tsekov, R

    2015-01-01

    A unified description of the catalytic effect of Cu-exchanged zeolites is proposed for the decomposition of NO. A general expression for the rate constant of NO decomposition is obtained by assuming that the rate-determining step consists of the transferring of a single atom associated with breaking of the N-O bond. The analysis is performed on the base of the generalized Langevin equation and takes into account both the potential interactions in the system and the memory effects due to the zeolite vibrations. Two different mechanisms corresponding to monomolecular and bimolecular NO decomposition are discussed. The catalytic effect in the monomolecular mechanism is related to both the Cu+ ions and zeolite O-vacancies, while in the case of the bimolecular mechanism the zeolite contributes through dissipation only. The comparison of the theoretically calculated rate constants with experimental results reveals additional information about the geometric and energetic characteristics of the active centers and con...

  1. Multiresolution signal decomposition schemes

    NARCIS (Netherlands)

    Goutsias, J.; Heijmans, H.J.A.M.

    1998-01-01

    [PNA-R9810] Interest in multiresolution techniques for signal processing and analysis is increasing steadily. An important instance of such a technique is the so-called pyramid decomposition scheme. This report proposes a general axiomatic pyramid decomposition scheme for signal analysis and synthes

  2. Influences of ammonia contamination on leaching from air-pollution-control residues.

    Science.gov (United States)

    Guan, Zhenzhen; Chen, Dezhen; Astrup, Thomas Fruergaard

    2014-12-01

    Application of selective non-catalytic reduction systems at municipal solid waste incinerators (MSWIs) often involves over-stoichiometric injection of ammonia into flue gases. Un-reacted ammonia may be deposited on fly ash particles and can ultimately influence the leaching behaviour of air-pollution-control (APC) residues. Batch tests were conducted to investigate the impacts of ammonia levels on leaching of a range of metals (sodium, potassium, calcium, aluminium, chromium, iron, lead, cadmium, copper, nickel and zinc), as well as chloride and dissolved organic carbon (DOC). Specific conductivity was also identified to reflect the soluble components. The results showed that with ammonia concentrations rising from a background level of 4 to 26,400 mg l(-1), the specific conductivity increased by 2-7 times as pH varied from alkaline to acidic values. DOC release was also significantly enhanced with high ammonia levels of 1400 mg l(-1) or higher at pH > 9; however at these high ammonia concentrations, the role of DOC in cadmium, copper, nickel and zinc leaching was negligible. Based on the experimental data, chloride, sodium and potassium were leached at high concentrations regardless of pH and ammonia concentrations. For aluminium, chromium, iron and lead, ammonia had little impact on their leaching behaviour. With respect to cadmium, copper, nickel and zinc, high ammonia concentrations significantly increased leaching in the pH range of 8-12 due to the formation of metal-ammonia complexes, which was also proved in the speciation calculations. However, the overall results suggest that typical levels of ammonia injection in MSWIs are not likely to affect metal leaching from APC residues. PMID:25147306

  3. Alteration of the Diastereoselectivity of 3-Methylaspartate Ammonia Lyase by Using Structure-Based Mutagenesis

    NARCIS (Netherlands)

    Raj, Hans; Weiner, Barbara; Puthan Veetil, Vinod; Reis, Carlos R.; Quax, Wim J.; Janssen, Dick B.; Feringa, Ben L.; Poelarends, Gerrit J.

    2009-01-01

    3-Methylaspartate ammonia-lyase (MAL) catalyzes the reversible amination of mesaconate to give both (2S,3S)-3-methylaspartic acid and (2S,3R)-3-methylaspartic acid as products. The deamination mechanism of MAL is likely to involve general base catalysis, in which a catalytic base abstracts the C3 pr

  4. Photochemical decomposition of H2O and HN3 using colloidal semiconductor catalysts as a method of tritium recovery from water

    International Nuclear Information System (INIS)

    Colloidal semiconductor redox catalysts were used to accelerate the photodecomposition of water and ammonia in aqueous solution. Parameters that affect overall catalytic efficiency, e.g. support material, doping and surface modification, were investigated

  5. Solid state synthesis, characterization, surface and catalytic properties of Pr2CoO4 and Pr2NiO4 catalyst

    International Nuclear Information System (INIS)

    Full text: The most interesting non-stoichiometric oxides are found in transition metal and rare earth oxides at higher temperatures. The role of Solid State properties in the catalysis using mixed metal oxide as catalyst have wide applications in fertilizer, Petro-chemical, Pharmaceutical, cosmetic, paint detergents, plastics and food-stuff industries and these are also resistive towards acids and alkalies. The use of catalyst has opened up new process routes or revolutioned the existing process in terms of economics and efficiency and has radically changed the industrial scenario. The use of catalyst is so pervasive today that nearly 70 % of modern chemical processes are based on it at some stage or other and 90% new processes developed are catalytic nature. A series of non-stoichiometric spinel type of oxide catalyst of Praseodymium with cobalt and nickel were synthesized by their oxalates through Solid State reaction technique at different activation temperatures i.e. 600, 700, 800 and 900 deg C. The characterization of catalyst was done by XRD, FTIR and ESR methods. X-ray powder diffraction study shows that catalysts are made up of well grown crystallinities mostly in single phase crystal and system is of orthorhombic structure. FTIR is related to inadequate decomposition of oxalate ion from the Catalyst. The kinetic decomposition of Urea was employed as a model reaction to study the catalytic potentiality of different catalysts. Surface and Catalytic Properties of catalysts were measured. A relation between activation temperature and surface properties like excess surface oxygen (E.S.O.), surface acidity and surface area was observed. A linear relationship between the surface area of the catalyst and the amount of ammonia gas evolved per gm of the sample was observed also. Nickel containing catalysts were found a bit more catalytic active in comparison to cobalt oxide catalysts. Transition metal ions (i.e. Ni2+and Co2+ ions) are mainly responsible for

  6. [Pathway of aqueous ferric hydroxide catalyzed ozone decomposition and ozonation of trace nitrobenzene].

    Science.gov (United States)

    Ma, Jun; Zhang, Tao; Chen, Zhong-lin; Sui, Ming-hao; Li, Xue-yan

    2005-03-01

    In this paper, the decomposition rate of ozone in water was measured over GAC and ferric hydroxide/GAC (FeOOH/GAC) catalyst and the mechanism of ozone catalytic decomposition was discussed. The catalytic ozonation activity of trace nitrobenzene in water was determined on several metal oxides and correlated with their surface density of hydroxyl groups and pHzpc,(pH of zero point of charge). The results show that: 1) The pseudo-first order rate of ozone decomposition increased by 68 and 108 percent for GAC and FeOOH/GAC catalysts respectively; 2) When t-butanol was added, the rate constant decreased by 9 % for GAC and 20% for FeOOH/GAC; 3) There was no direct correlation between surface density of hydroxyl groups and the activity of catalytic ozonation of nitrobenzene; 4) The oxide surface at nearly zero charged point was favorable for the catalytic ozonation of nitrobenzene.

  7. Radiation decomposition of alcohols and chloro phenols in micellar systems

    International Nuclear Information System (INIS)

    The effect of surfactants on the radiation decomposition yield of alcohols and chloro phenols has been studied with gamma doses of 2, 3, and 5 KGy. These compounds were used as typical pollutants in waste water, and the effect of the water solubility, chemical structure, and the nature of the surfactant, anionic or cationic, was studied. The results show that anionic surfactant like sodium dodecylsulfate (SDS), improve the radiation decomposition yield of ortho-chloro phenol, while cationic surfactant like cetyl trimethylammonium chloride (CTAC), improve the radiation decomposition yield of butyl alcohol. A similar behavior is expected for those alcohols with water solubility close to the studied ones. Surfactant concentrations below critical micellar concentration (CMC), inhibited radiation decomposition for both types of alcohols. However radiation decomposition yield increased when surfactant concentrations were bigger than the CMC. Aromatic alcohols decomposition was more marked than for linear alcohols decomposition. On a mixture of alcohols and chloro phenols in aqueous solution the radiation decomposition yield decreased with increasing surfactant concentration. Nevertheless, there were competitive reactions between the alcohols, surfactants dimers, hydroxyl radical and other reactive species formed on water radiolysis, producing a catalytic positive effect in the decomposition of alcohols. Chemical structure and the number of carbons were not important factors in the radiation decomposition. When an alcohol like ortho-chloro phenol contained an additional chlorine atom, the decomposition of this compound was almost constant. In conclusion the micellar effect depend on both, the nature of the surfactant (anionic or cationic) and the chemical structure of the alcohols. The results of this study are useful for wastewater treatment plants based on the oxidant effect of the hydroxyl radical, like in advanced oxidation processes, or in combined treatment such as

  8. Lattice dynamics of ammonia

    International Nuclear Information System (INIS)

    The frequencies of selected intermolecular modes of vibration and libration in a single crystal of deuterated ammonia (ND3) have been measured by the technique of coherent inelastic neutron scattering, at temperatures of 20 and 95K. The results are compared with the previous optical measurements at the Γ point, and with calculations based on two different models for the intermolecular potential function. A detailed assessment of these data leads to a set of mode frequencies for the Γ, R, and M points. The elastic constants are calculated from the measured acoustic mode dispersion curves propagating along the three major symmetry directions. The existing intermolecular force models are in good qualitative agreement with experiment, but significant discrepancies remain to be resolved by future theoretical refinements. (author)

  9. A comparative kinetic study of SNCR process using ammonia

    Energy Technology Data Exchange (ETDEWEB)

    Javed, M. Tayyeb; Ahmed, Z.; Ibrahim, M. Asim; Irfan, N.

    2008-07-01

    The paper presents comparative kinetic modelling of nitrogen oxides (NOx) removal from flue gases by selective non-catalytic reduction process using ammonia as reducing agent. The computer code SENKIN is used in this study with the three published chemical kinetic mechanisms; Zanoelo, Kilpinen and Skreiberg. Kinetic modeling was performed for an isothermal plug flow reactor at atmospheric pressure so as to compare it with the experimental results. A 500 ppm NOx background in the flue gas is considered and kept constant throughout the investigation. The ammonia performance was modeled in the range of 750 to 1250{sup o}C using the molar ratios NH{sub 3}/NOx from 0.25 to 3.0 and residence times up to 1.5 seconds. The modeling using all the mechanisms exhibits and confirms a temperature window of NOx reduction with ammonia. It was observed that 80% of NOx reduction efficiency could be achieved if the flue gas is given 300 msec to react with ammonia, while it is passing through a section within a temperature range of 910 to 1060{sup o}C (Kilpinen mechanism) or within a temperature range of 925 to 1030{sup o}C (Zanoelo mechanism) or within a temperature range of 890 to 1090{sup o}C (Skreiberg mechanism). 20 refs., 6 figs.

  10. Iron-Catalyzed Boron Removal from Molten Silicon in Ammonia

    Science.gov (United States)

    Chen, Zhiyuan; Morita, Kazuki

    2016-05-01

    A high-temperature process of refining metallurgical-grade silicon to solar-grade silicon was developed. In this gas purging treatment, boron impurity in silicon reacts with ammonia and the products are removed as volatiles at high temperature. 1 mass pct metallic iron was added to molten silicon as a catalyst, improving the boron removal ratio from 14 to 80 pct at 1723 K (1450 °C). At 1823 K (1550 °C), this reaction could reduce boron concentration from more than 120 ppmw to <1 ppmw within 6 hours, meeting the purity requirement of solar-grade silicon. Nickel was tested in place of iron but showed no catalytic effect on boron removal. The result confirmed the catalytic role of iron in boron removal from molten silicon in ammonia. Possible mechanisms of catalysis, influence from iron concentration, and temperature effect on the catalytic reaction were explored. An apparent activation energy of 329 ± 129 kJ mol-1 was calculated from experimental data.

  11. Catalytic Synthesis of Nitriles in Continuous Flow

    DEFF Research Database (Denmark)

    Nordvang, Emily Catherine

    The objective of this thesis is to report the development of a new, alternative process for the flexible production of nitrile compounds in continuous flow. Nitriles are an important class of compounds that find applications as solvents, chemical intermediates and pharmaceutical compounds......, alternative path to acetonitrile from ethanol via the oxidative dehydrogenation of ethylamine. The catalytic activity and product ratios of the batch and continuous flow reactions are compared and the effect of reaction conditions on the reaction is investigated. The effects of ammonia in the reaction...... dehydrogenation of ethylamine and post-reaction purging.Chapter 4 outlines the application of RuO2/Al2O3 catalysts to the oxidative dehydrogenation of benzylamine in air, utilizing a new reaction setup. Again, batch and continuous flow reactions are compared and the effects of reaction conditions, ammonia...

  12. Ammonia Ice Clouds on Jupiter

    Science.gov (United States)

    2007-01-01

    The top cloud layer on Jupiter is thought to consist of ammonia ice, but most of that ammonia 'hides' from spectrometers. It does not absorb light in the same way ammonia does. To many scientists, this implies that ammonia churned up from lower layers of the atmosphere 'ages' in some way after it condenses, possibly by being covered with a photochemically generated hydrocarbon mixture. The New Horizons Linear Etalon Imaging Spectral Array (LEISA), the half of the Ralph instrument that is able to 'see' in infrared wavelengths that are absorbed by ammonia ice, spotted these clouds and watched them evolve over five Jupiter days (about 40 Earth hours). In these images, spectroscopically identified fresh ammonia clouds are shown in bright blue. The largest cloud appeared as a localized source on day 1, intensified and broadened on day 2, became more diffuse on days 3 and 4, and disappeared on day 5. The diffusion seemed to follow the movement of a dark spot along the boundary of the oval region. Because the source of this ammonia lies deeper than the cloud, images like these can tell scientists much about the dynamics and heat conduction in Jupiter's lower atmosphere.

  13. Sustainable Ammonia Synthesis – Exploring the scientific challenges associated with discovering alternative, sustainable processes for ammonia production

    Energy Technology Data Exchange (ETDEWEB)

    Nørskov, Jens [Stanford Univ., CA (United States); ; SLAC National Accelerator Lab., Menlo Park, CA (United States); Chen, Jingguang [Columbia Univ., New York, NY (United States); Brookhaven National Lab. (BNL), Upton, NY (United States); Miranda, Raul [Dept. of Energy (DOE), Washington DC (United States). Office of Science; Fitzsimmons, Tim [Dept. of Energy (DOE), Washington DC (United States). Office of Science; Stack, Robert [Dept. of Energy (DOE), Washington DC (United States). Office of Science

    2016-02-18

    Ammonia (NH3) is essential to all life on our planet. Until about 100 years ago, NH3 produced by reduction of dinitrogen (N2) in air came almost exclusively from bacteria containing the enzyme nitrogenase.. DOE convened a roundtable of experts on February 18, 2016. Participants in the Roundtable discussions concluded that the scientific basis for sustainable processes for ammonia synthesis is currently lacking, and it needs to be enhanced substantially before it can form the foundation for alternative processes. The Roundtable Panel identified an overarching grand challenge and several additional scientific grand challenges and research opportunities: -Discovery of active, selective, scalable, long-lived catalysts for sustainable ammonia synthesis. -Development of relatively low pressure (<10 atm) and relatively low temperature (<200 C) thermal processes. -Integration of knowledge from nature (enzyme catalysis), molecular/homogeneous and heterogeneous catalysis. -Development of electrochemical and photochemical routes for N2 reduction based on proton and electron transfer -Development of biochemical routes to N2 reduction -Development of chemical looping (solar thermochemical) approaches -Identification of descriptors of catalytic activity using a combination of theory and experiments -Characterization of surface adsorbates and catalyst structures (chemical, physical and electronic) under conditions relevant to ammonia synthesis.

  14. Selective catalytic reduction operation with heavy fuel oil: NOx, NH3, and particle emissions.

    Science.gov (United States)

    Lehtoranta, Kati; Vesala, Hannu; Koponen, Päivi; Korhonen, Satu

    2015-04-01

    To meet stringent NOx emission limits, selective catalytic reduction (SCR) is increasingly utilized in ships, likely also in combination with low-priced higher sulfur level fuels. In this study, the performance of SCR was studied by utilizing NOx, NH3, and particle measurements. Urea decomposition was studied with ammonia and isocyanic acid measurements and was found to be more effective with heavy fuel oil (HFO) than with light fuel oil. This is suggested to be explained by the metals found in HFO contributing to metal oxide particles catalyzing the hydrolysis reaction prior to SCR. At the exhaust temperature of 340 °C NOx reduction was 85-90%, while at lower temperatures the efficiency decreased. By increasing the catalyst loading, the low temperature behavior of the SCR was enhanced. The drawback of this, however, was the tendency of particle emissions (sulfate) to increase at higher temperatures with higher loaded catalysts. The particle size distribution results showed high amounts of nanoparticles (in 25-30 nm size), the formation of which SCR either increased or decreased. The findings of this work provide a better understanding of the usage of SCR in combination with a higher sulfur level fuel and also of ship particle emissions, which are a growing concern.

  15. Synthesis and catalytic properties of metal clusters encapsulated within small-pore (SOD, GIS, ANA) zeolites.

    Science.gov (United States)

    Goel, Sarika; Wu, Zhijie; Zones, Stacey I; Iglesia, Enrique

    2012-10-24

    The synthesis protocols for encapsulation of metal clusters reported here expand the diversity in catalytic chemistries made possible by the ability of microporous solids to select reactants, transition states, and products on the basis of their molecular size. We report a synthesis strategy for the encapsulation of noble metals and their oxides within SOD (Sodalite, 0.28 nm × 0.28 nm), GIS (Gismondine, 0.45 nm × 0.31 nm), and ANA (Analcime, 0.42 nm × 0.16 nm) zeolites. Encapsulation was achieved via direct hydrothermal synthesis for SOD and GIS using metal precursors stabilized by ammonia or organic amine ligands, which prevent their decomposition or precipitation as colloidal hydroxides at the conditions of hydrothermal synthesis (12), thereby causing precipitation of even ligand-stabilized metal precursors as hydroxides. As a result, encapsulation was achieved by the recrystallization of metal clusters containing GIS into ANA, which retained these metal clusters within voids throughout the GIS-ANA transformation.

  16. Spectral proper orthogonal decomposition

    CERN Document Server

    Sieber, Moritz; Paschereit, Christian Oliver

    2015-01-01

    The identification of coherent structures from experimental or numerical data is an essential task when conducting research in fluid dynamics. This typically involves the construction of an empirical mode base that appropriately captures the dominant flow structures. The most prominent candidates are the energy-ranked proper orthogonal decomposition (POD) and the frequency ranked Fourier decomposition and dynamic mode decomposition (DMD). However, these methods fail when the relevant coherent structures occur at low energies or at multiple frequencies, which is often the case. To overcome the deficit of these "rigid" approaches, we propose a new method termed Spectral Proper Orthogonal Decomposition (SPOD). It is based on classical POD and it can be applied to spatially and temporally resolved data. The new method involves an additional temporal constraint that enables a clear separation of phenomena that occur at multiple frequencies and energies. SPOD allows for a continuous shifting from the energetically ...

  17. Inhibition of Direct Electrolytic Ammonia Oxidation Due to a Change in Local pH

    International Nuclear Information System (INIS)

    Electrochemical ammonia oxidation has gained a lot of attention recently as an efficient method for ammonia removal from wastewater, for the use in ammonia-based fuel cells and the production of high purity hydrogen. Thermally decomposed iridium oxide films (TDIROF) have been shown to be catalytically active for direct ammonia oxidation in aqueous solutions if NH3 is present. However, the process was reported to be rapidly inhibited on TDIROF. Herein, we show that this fast inhibition of direct ammonia oxidation does not result from surface poisoning by adsorbed elemental nitrogen (Nads). Instead, we propose that direct ammonia oxidation and oxygen evolution can lead to a drop of the local pH at the electrode resulting in a low availability of the actual reactant, NH3. The hypothesis was tested with cyclic voltammetry (CV) experiments on stagnant and rotating disk electrodes (RDE). The CV experiments on the stagnant electrode revealed that the decrease of the ammonia oxidation peaks was considerably reduced by introducing an idle phase at open circuit potential between subsequent scans. Furthermore, the polarization of the TDIROF electrode into the hydrogen evolution region (HER) resulted in increased ammonia oxidation peaks in the following anodic scans which can be explained with an increased local pH after the consumption of protons in the HER. On the RDE, the ammonia oxidation peaks did not decrease in immediately consecutive scans. These findings would not be expected if surface poisoning was responsible for the fast inhibition but they are in good agreement with the proposed mechanism of pH induced limitation by the reactant, NH3. The plausibility of the mechanism was also supported by our numerical simulations of the processes in the Nernstian diffusion layer. The knowledge about this inhibition mechanism of direct ammonia oxidation is especially important for the design of electrochemical cells for wastewater treatment. The mechanism is not only valid for

  18. The effect of soot on ammonium nitrate species and NO2 selective catalytic reduction over Cu-zeolite catalyst-coated particulate filter.

    Science.gov (United States)

    Mihai, Oana; Tamm, Stefanie; Stenfeldt, Marie; Olsson, Louise

    2016-02-28

    A selective catalytic reduction (SCR)-coated particulate filter was evaluated by means of dynamic tests performed using NH3, NO2, O2 and H2O. The reactions were examined both prior to and after soot removal in order to study the effect of soot on ammonium nitrate formation and decomposition, ammonia storage and NO2 SCR. A slightly larger ammonia storage capacity was observed when soot was present in the sample, which indicated that small amounts of ammonia can adsorb on the soot. Feeding of NO2 and NH3 in the presence of O2 and H2O at low temperature (150, 175 and 200°C) leads to a large formation of ammonium nitrate species and during the subsequent temperature ramp using H2O and argon, a production of nitrous oxides was observed. The N2O formation is often related to ammonium nitrate decomposition, and our results showed that the N2O formation was clearly decreased by the presence of soot. We therefore propose that in the presence of soot, there are fewer ammonium nitrate species on the surface due to the interactions with the soot. Indeed, we do observe CO2 production during the reaction conditions also at 150°C, which shows that there is a reaction with these species and soot. In addition, the conversion of NOx due to NO2 SCR was significantly enhanced in the presence of soot; we attribute this to the smaller amount of ammonium nitrate species present in the experiments where soot is available since it is well known that ammonium nitrate formation is a major problem at low temperature due to the blocking of the catalytic sites. Further, a scanning electron microscopy analysis of the soot particles shows that they are about 30-40 nm and are therefore too large to enter the pores of the zeolites. There are likely CuxOy or other copper species available on the outside of the zeolite crystallites, which could have been enhanced due to the hydrothermal treatment at 850°C of the SCR-coated filter prior to the soot loading. We therefore propose that soot is

  19. The effect of soot on ammonium nitrate species and NO2 selective catalytic reduction over Cu-zeolite catalyst-coated particulate filter.

    Science.gov (United States)

    Mihai, Oana; Tamm, Stefanie; Stenfeldt, Marie; Olsson, Louise

    2016-02-28

    A selective catalytic reduction (SCR)-coated particulate filter was evaluated by means of dynamic tests performed using NH3, NO2, O2 and H2O. The reactions were examined both prior to and after soot removal in order to study the effect of soot on ammonium nitrate formation and decomposition, ammonia storage and NO2 SCR. A slightly larger ammonia storage capacity was observed when soot was present in the sample, which indicated that small amounts of ammonia can adsorb on the soot. Feeding of NO2 and NH3 in the presence of O2 and H2O at low temperature (150, 175 and 200°C) leads to a large formation of ammonium nitrate species and during the subsequent temperature ramp using H2O and argon, a production of nitrous oxides was observed. The N2O formation is often related to ammonium nitrate decomposition, and our results showed that the N2O formation was clearly decreased by the presence of soot. We therefore propose that in the presence of soot, there are fewer ammonium nitrate species on the surface due to the interactions with the soot. Indeed, we do observe CO2 production during the reaction conditions also at 150°C, which shows that there is a reaction with these species and soot. In addition, the conversion of NOx due to NO2 SCR was significantly enhanced in the presence of soot; we attribute this to the smaller amount of ammonium nitrate species present in the experiments where soot is available since it is well known that ammonium nitrate formation is a major problem at low temperature due to the blocking of the catalytic sites. Further, a scanning electron microscopy analysis of the soot particles shows that they are about 30-40 nm and are therefore too large to enter the pores of the zeolites. There are likely CuxOy or other copper species available on the outside of the zeolite crystallites, which could have been enhanced due to the hydrothermal treatment at 850°C of the SCR-coated filter prior to the soot loading. We therefore propose that soot is

  20. Contact handle decompositions

    OpenAIRE

    Özbağcı, Burak

    2009-01-01

    We review Giroux’s contact handles and contact handle attachments in dimension three and show that a bypass attachment consists of a pair of contact 1 and 2-handles. As an application we describe explicit contact handle decompositions of infinitely many pairwise non-isotopic overtwisted 3-spheres. We also give an alternative proof of the fact that every compact contact 3-manifold (closed or with convex boundary) admits a contact handle decomposition, which is a result originally due to Giroux.

  1. Ammonia-oxidizing archaea have more important role than ammonia-oxidizing bacteria in ammonia oxidation of strongly acidic soils

    OpenAIRE

    Zhang, Li-Mei; Hu, Hang-Wei; Shen, Ju-Pei; He, Ji-Zheng

    2011-01-01

    Increasing evidence demonstrated the involvement of ammonia-oxidizing archaea (AOA) in the global nitrogen cycle, but the relative contributions of AOA and ammonia-oxidizing bacteria (AOB) to ammonia oxidation are still in debate. Previous studies suggest that AOA would be more adapted to ammonia-limited oligotrophic conditions, which seems to be favored by protonation of ammonia, turning into ammonium in low-pH environments. Here, we investigated the autotrophic nitrification activity of AOA...

  2. 21 CFR 573.180 - Anhydrous ammonia.

    Science.gov (United States)

    2010-04-01

    ... 21 Food and Drugs 6 2010-04-01 2010-04-01 false Anhydrous ammonia. 573.180 Section 573.180 Food... Additive Listing § 573.180 Anhydrous ammonia. (a) The food additive anhydrous ammonia is applied directly...: (1)(i) The food additive anhydrous ammonia is applied as a component of an aqueous premix...

  3. Heterogeneous Photocatalytic Degradation Kinetic of Gaseous Ammonia Over Nano-TiO2 Supported on Latex Paint Film

    Institute of Scientific and Technical Information of China (English)

    QI-JIN GENG; XI-KUI WANG; SHAN-FANG TANG

    2008-01-01

    Objective To investigate the photoeatalytic degradation of gaseous ammonia in static state by using nano-TiO2 as photocatalyst supported on latex paint film under UV-irradiation.Methods Experiments were conducted to study the relationship between the initial concentration of ammonia and the degradation products competing to be adsorbed on catalyst surface.Degradation of ammonia and its products were detected by spectrophotometry and catalytic kinetic spectrophotometry,respectively.Results On the one hand,TiO2 catalyst was excellent for degradation of ammonia,and the crystal phase of TiO2,anatase or rutile,had little effect on degradation of ammonia,but the conversion of ammonia grew with the increase of catalyst content.On the other hand,apparent rate constant and conversion of anmaoma decreased with the increase of initial concentration of ammonia,and the photocatalytic degradation reaction followed a pseudo-first-order expression due to the evidence of linear correlation between-lnC/Co vs.irradiation time t, but the relationship between initial concentration and the degradation products Was not linear in low initial concentration.Conclusion Whether the photocatalytic degradation of ammonia in static state follows a first-order reaction depends on the initial ammonia concentration due to competition in adsorption between reactant and the degradation products.

  4. Solubility of ammonia in rainwater

    OpenAIRE

    G. P. Ayers; Gras, J. L.; Adriaansen, A.; Gillett, R. W.

    2011-01-01

    Partitioning of ammonia between the gaseous and rainwater phases has been investigated at theAustralian Baseline Air Pollution Station during in-situ experiments in which rainwater andammonia gas were sampled concurrently. The relationship between ammonia concentrations inthe gaseous and aqueous phases did not follow either traditional solubility theory based onHenry’s Law, or a recent modified theory that includes secondary equilibria between dissolvedammonia and carbon dioxide.DOI: 10.1111/...

  5. Vanadia supported on zeolites for SCR of NO by ammonia

    DEFF Research Database (Denmark)

    Putluru, Siva Sankar Reddy; Riisager, Anders; Fehrmann, Rasmus

    2010-01-01

    in the selective catalytic reduction (SCR) of NO with ammonia. The SCR activity was found to correlate directly with the total acidity of the catalysts and showed high poisoning resistivity after doping with potassium oxide (100 mu mol/g). The poisoning resistance was due to unique combination of high surface area......, acidity and micropore structure of the support. Apparently the support hosted the potassium oxide on the acid sites, thereby protecting the active vanadium species from poisoning. Zeolite based catalysts might therefore prove useful for SCR of NO in alkali-containing flue gases from, e.g. biomass fired...

  6. Forced convection of ammonia. 2. part.: gaseous ammonia - very high wall temperatures (1000 to 3000 K)

    International Nuclear Information System (INIS)

    Heat transfer coefficients and pressure drop of gaseous ammonia in forced convection are experimentally determined. The fluid flows (mass flow rate 0.6 to 2.4 g/s) in a long tungsten tube (di = 2.8 mm, de = 5.1 mm, L = 700 mm) electrically heated. The temperature of the wall reaches 3000 deg. K and the fluid 2500 deg. K; maximum heat flux 530 w/cm2. Ammonia is completely dissociated and the power necessary for dissociation reaches 30 per cent of the total power exchanged. Inlet pressure varies between 6 and 16 bars and the maximum pressure drop in the tube reaches 15 bars. Two regimes of dissociation have been shown: catalytic and homogeneous and the variation of dissociation along the length of the tube is studied. The measured heat transfer coefficients may be about 10 times these calculated by the means of classical formulae. A correlation of experimental results using enthalpy as a driving force for heat transmission is presented. Pressure drops may be calculated by the means of a classical friction factor. (authors)

  7. Thermal decomposition of cyclotriborazane

    Energy Technology Data Exchange (ETDEWEB)

    Schellenberg, R. [Technische Universitaet Bergakademie Freiberg, Institute of Physical Chemistry, Leipziger Str. 29, 09599 Freiberg (Germany)]. E-mail: Rene.Schellenberg@chemie.tu-freiberg.de; Kriehme, J. [Technische Universitaet Bergakademie Freiberg, Institute of Physical Chemistry, Leipziger Str. 29, 09599 Freiberg (Germany); Wolf, G. [Technische Universitaet Bergakademie Freiberg, Institute of Physical Chemistry, Leipziger Str. 29, 09599 Freiberg (Germany)

    2007-06-15

    Cyclotriborazane (CTB), B{sub 3}N{sub 3}H{sub 12}, is a crystalline white solid, which decomposes above 400 K to hydrogen and a few other products, depending on the reaction conditions. In this work we present investigations of the thermal decomposition of both the neat compound and CTB dissolved in diglyme and tetraglyme. Several thermophysical and analytical methods, such as differential scanning calorimetry (DSC), thermogravimetry (TG), mass spectroscopy (QMS), and {sup 11}B nuclear magnetic resonance spectroscopy (NMR) have been used for this investigation. The decomposition of the neat substance releases 3.1 mol H{sub 2}/mol CTB and leads to a polymeric products and borazine. In open vessels, sublimation as a competing process also occurs. The enthalpy of the decomposition process ({delta}{sub R} H {sub s}) has been determined as {delta}{sub R} H {sub s} = -34.0 {+-} 2.9 kJ/mol. In contrast to the thermal decomposition of the pure substance, the decomposition in polyethers, such as diglyme and tetraglyme, leads above 370 K to borazine and small amounts of soluble oligomeric borazine species. Also BH{sub 3} group containing species are occurring as intermediates. In these systems no precipitation was detected. DSC measurements show for the decomposition in solution several strong exothermic effects. The overall decomposition enthalpy in diglyme is given by {delta}{sub R} H {sub d} = -32.0 {+-} 2.8 kJ/mol and in tetraglyme by {delta}{sub R} H {sub t} = -48.0 {+-} 4.7 kJ/mol. The enthalpy of solution of cyclotriborazane was determined in diglyme and in tetraglyme with the values {delta}{sub D} H {sub d} = -2.1 {+-} 0.2 kJ/mol and {delta}{sub D} H {sub t} = -4.6 {+-} 0.5 kJ/mol, respectively.

  8. Catalytic abatement of nitrous oxide from nitric and production

    NARCIS (Netherlands)

    Oonk, J.

    1998-01-01

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

  9. Study of the acceleration of ammonia generation process from poultry residues aiming at hydrogen production

    International Nuclear Information System (INIS)

    The hydrogen, utilized in fuel cells, can be produced from a variety of intermediate chemicals, between them, the ammonia. The ammonia gas as a raw material for the hydrogen production has been used due to its high energetic content, facility of decomposition, high availability, low prices, low storage pressure and its by-products are environmentally correct. One of the sources of ammonia is poultry and egg production systems. In these systems the ammonia is produced from the decomposition of uric acid present in the excreta of birds. The residue from the poultry-rearing farms is the broiler litter and from the egg production system is the excreta without any substrate. The characterization of these residues was performed using the Wavelength-Dispersive X-Ray Fluorescence (WDXRF), Elementary Analysis (CHN), Thermogravimetry and GC/MS - Gas chromatography/ Mass spectrometry. The studied factors which influence the ammonia volatilization were: nitrogen content, raising period, urease enzyme, temperature, pH and moisture content. The experiment results with poultry litter and excreta allow to conclude that the manipulation of the following parameters increased the ammonia emission: pH, nitrogen content, raising period, age of birds and excreta accumulation, urease enzyme and the temperature. The addition of different amounts of sand in the excreta and different volumes of water in the poultry litter inhibited the emission of ammonia. The variation of the quantity of material (broiler litter or excreta) and the volume of the flask used as incubator chamber showed no significant alterations to be chosen as a variable. The excreta was considered more appropriate than poultry litter for the objectives of this work due to the higher ammonia concentrations determined in this material. Due to the large amount of poultry litter and excreta from the production processes, the reuse of poultry residues to obtain ammonia is necessary to improve the quality of the local

  10. Catalytic pyrolysis of Pubescens to phenols over Ni/C catalyst

    Institute of Scientific and Technical Information of China (English)

    2010-01-01

    The pyrolysis of Pubescens over Ni/C catalyst was studied at 350°C in H2 flow.The presence of Ni/C catalyst efficiently improved the degradation of raw materials,and produced bio-oil with high content of phenols but low contents of acetic acid,furfural and water.In the reaction,Ni/C catalyst plays the role of catalytic decomposition and catalytic hydrogenation.The existence of the carbon carrier favors the formation of active Ni in small sizes with more defects,which results in high catalytic activity of Ni in biomass decomposition and selective production of phenols.

  11. Global Seabird Ammonia Emissions

    Science.gov (United States)

    Riddick, S. N.; Blackall, T. D.; Dragosits, U.; Daunt, F. H.; Braban, C. F.; Tang, Y. S.; Trathan, P.; Wanless, S.; Sutton, M. A.

    2010-12-01

    Seabird colonies represent a major source of atmospheric ammonia (NH3) in remote coastal and marine systems in temperate, tropical and polar regions. Previous studies have shown that NH3 emissions from Scottish seabird colonies were substantial - of similar magnitude to the most intensive agricultural point source emissions. The UK data were used to model global seabird NH3 emissions and suggested that penguins are a major source of emissions on and around the Antarctic continent. The largest seabird colonies are in the order of millions of seabirds. Due to the isolation of these colonies from anthropogenic nitrogen sources, they may play a major role in the nitrogen cycle within these ecosystems. A global seabird database was constructed and used in conjunction with a species-specific seabird bioenergetics model to map the locations of NH3 emissions from seabird colonies. The accuracy of the modelled emissions was validated with field data of NH3 emissions measured at key seabird colonies in different climatic regions of the world: temperate (Isle of May, Scotland), tropical (Ascension Island) and polar (Signy Island, South Georgia). The field data indicated good agreement between modelled and measured NH3 emissions. The measured NH3 emissions also showed the variability of emission with climate. Climate dependence of seabird NH3 emissions may have further implications under a changing global climate. Seabird colonies represent NH3 emission ‘hotspots’, often far from anthropogenic sources, and are likely to be the major source of nitrogen input to these remote coastal ecosystems. The direct manuring by seabirds at colony locations may strongly influence species richness and biodiversity. The subsequent volatilisation and deposition of NH3 increases the spatial extent of seabird influence on nitrogen cycling in their local ecosystem. As many seabird populations are fluctuating due to changing food supply, climate change or anthropogenic pressures, these factors

  12. Decomposing Nekrasov Decomposition

    CERN Document Server

    Morozov, A

    2015-01-01

    AGT relations imply that the four-point conformal block admits a decomposition into a sum over pairs of Young diagrams of essentially rational Nekrasov functions - this is immediately seen when conformal block is represented in the form of a matrix model. However, the q-deformation of the same block has a deeper decomposition - into a sum over a quadruple of Young diagrams of a product of four topological vertices. We analyze the interplay between these two decompositions, their properties and their generalization to multi-point conformal blocks. In the latter case we explain how Dotsenko-Fateev all-with-all (star) pair "interaction" is reduced to the quiver model nearest-neighbor (chain) one. We give new identities for q-Selberg averages of pairs of generalized Macdonald polynomials. We also translate the slicing invariance of refined topological strings into the language of conformal blocks and interpret it as abelianization of generalized Macdonald polynomials.

  13. Decomposing Nekrasov decomposition

    Science.gov (United States)

    Morozov, A.; Zenkevich, Y.

    2016-02-01

    AGT relations imply that the four-point conformal block admits a decomposition into a sum over pairs of Young diagrams of essentially rational Nekrasov functions — this is immediately seen when conformal block is represented in the form of a matrix model. However, the q-deformation of the same block has a deeper decomposition — into a sum over a quadruple of Young diagrams of a product of four topological vertices. We analyze the interplay between these two decompositions, their properties and their generalization to multi-point conformal blocks. In the latter case we explain how Dotsenko-Fateev all-with-all (star) pair "interaction" is reduced to the quiver model nearest-neighbor (chain) one. We give new identities for q-Selberg averages of pairs of generalized Macdonald polynomials. We also translate the slicing invariance of refined topological strings into the language of conformal blocks and interpret it as abelianization of generalized Macdonald polynomials.

  14. Side reactions in the selective catalytic reduction of NO with NH{sub 3}

    Energy Technology Data Exchange (ETDEWEB)

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

    2002-03-01

    The main and the side reactions of the SCR reaction with ammonia over TiO{sub 2}-WO{sub 3}-V{sub 2}O{sub 5} catalysts have been investigated using synthetic gas mixtures matching the composition of diesel exhaust. At high temperatures the selective catalytic oxidation of ammonia (SCO) and the formation of nitrous oxide compete with the SCR reaction. Water strongly inhibits the SCO of ammonia and the formation of nitrous oxide thus increasing the selectivity of the SCR reaction. However, water also inhibits SCR activity, most pronounced at low temperatures. (author)

  15. Mueller matrix differential decomposition.

    Science.gov (United States)

    Ortega-Quijano, Noé; Arce-Diego, José Luis

    2011-05-15

    We present a Mueller matrix decomposition based on the differential formulation of the Mueller calculus. The differential Mueller matrix is obtained from the macroscopic matrix through an eigenanalysis. It is subsequently resolved into the complete set of 16 differential matrices that correspond to the basic types of optical behavior for depolarizing anisotropic media. The method is successfully applied to the polarimetric analysis of several samples. The differential parameters enable one to perform an exhaustive characterization of anisotropy and depolarization. This decomposition is particularly appropriate for studying media in which several polarization effects take place simultaneously. PMID:21593943

  16. Equations of state of detonation products: ammonia and methane

    Science.gov (United States)

    Lang, John; Dattelbaum, Dana; Goodwin, Peter; Garcia, Daniel; Coe, Joshua; Leiding, Jeffery; Gibson, Lloyd; Bartram, Brian

    2015-06-01

    Ammonia (NH3) and methane (CH4) are two principal product gases resulting from explosives detonation, and the decomposition of other organic materials under shockwave loading (such as foams). Accurate thermodynamic descriptions of these gases are important for understanding the detonation performance of high explosives. However, shock compression data often do not exist for molecular species in the dense gas phase, and are limited in the fluid phase. Here, we present equation of state measurements of elevated initial density ammonia and methane gases dynamically compressed in gas-gun driven plate impact experiments. Pressure and density of the shocked gases on the principal Hugoniot were determined from direct particle velocity and shock wave velocity measurements recorded using optical velocimetry (Photonic Doppler velocimetry (PDV) and VISAR (velocity interferometer system for any reflector)). Streak spectroscopy and 5-color pyrometry were further used to measure the emission from the shocked gases, from which the temperatures of the shocked gases were estimated. Up to 0.07 GPa, ammonia was not observed to ionize, with temperature remaining below 7000 K. These results provide quantitative measurements of the Hugoniot locus for improving equations of state models of detonation products.

  17. Ammonia Volatilization from Urea Applied to Acid Paddy Soil in Southern China and Its Control

    Institute of Scientific and Technical Information of China (English)

    CAIGUI-XIN; PENGGUANG-HAO; 等

    1992-01-01

    Results showed that ammonia loss from urea broadcast into floodwater and incorporated into soil at transplanting was as high as 40% of applied N,and the corresponding total nitrogen (N) loss was 56%.Ammonia loss was measured with simplified micrometeorological method (ammonia sampler),and total N loss was concurrently measured using 15N balance technique.The experiment was conducted under strong sunshine conditions on acid paddy soil derived from Quaternary red clay.The ammonia loss in this particular condition was much greater than those obtained from previous studies when urea was also applied to acid paddy soil but under cloudy conditions.It is concluded that the strong sunshine conditions with high temperature and shallow floodwater during the period of present experiment favoured ammonia volatilization.Application of stearyl alcohol on the surface of the floodwater reduced ammonia loss to 23% of applied N.However,the effect of stearyl alcohol was short-lived,probably due to the microbiological decomposition.

  18. Thermal Decomposition of Gelled UO3

    International Nuclear Information System (INIS)

    The thermal decomposition behavior of gelled UO3 microspheres have beenstudied. The thermal analysis included DTA and TG with XRD analysisexamination. The gelled were prepared by reacting uranyl nitrate with urea +HMTA, then dropped into a column containing paraffin oil at temperature of 95oC. The obtained gel were washed using NH40H and then dried. There wereanalyzed their thermal behavior using STA (Simultaneous Thermal Analyzer) upto 700 oC and were prepared for XRD analysis by heating at 200 oC, 400 oC,500 oC and 600 oC. The results showed that thermal decomposition of gelledUO3 microsphere consisted of five steps. The first and second steps wereendothermic reaction of the removal of the physics absorbed water started at100 oC, and the removal of chemically bounded water. The third and fourthsteps were exothermic reactions of the ammonia removal and the last steps wasexothermic reaction of change of compound UO3.xNH3 to U3O8. The XRDpatterns showed that compound of gelled UO3, which had been heated at 600oC give an indication the form of U3O8 compound, so that the minimumtemperature of calcination was 600 oC. (author)

  19. Study of ammonia process generation from the avian residues aiming the hydrogen production; Estudo do processo da geracao de amonia a partir de residuos avicolas visando a producao de hidrogenio

    Energy Technology Data Exchange (ETDEWEB)

    Egute, Nayara dos Santos; Abrao, Alcidio; Carvalho, Fatima Maria Sequeira de [Instituto de Pesquisas Energeticas e Nucleares (IPEN/CNEN-SP), Sao Paulo, SP (Brazil)], e-mail: nayara.egute@usp.br

    2010-03-15

    The hydrogen used in fuel cells can be classified as green or black hydrogen. Ammonia as an hydrogen source has the great advantage of being carbon-free. One of the sources of ammonia is poultry and egg production systems. In these systems the ammonia is produced from the decomposition of uric acid present in the excreta of birds. Among the factors which influence the ammonia volatilization, are the pH and the nitrogen content. Poultry litter and excreta isolated were also analyzed, The addition of sodium carbonate, with the rise of pH promoted an increase in the levels of ammonia volatilization. The high nitrogen excreta presented higher ammonia volatilization than the other one. The excreta was considered more appropriate than poultry litter for the objectives of this work due to the higher ammonia concentrations determined int his material. (author)

  20. Symmetric Tensor Decomposition

    DEFF Research Database (Denmark)

    Brachat, Jerome; Comon, Pierre; Mourrain, Bernard;

    2010-01-01

    of polynomial equations of small degree in non-generic cases. We propose a new algorithm for symmetric tensor decomposition, based on this characterization and on linear algebra computations with Hankel matrices. The impact of this contribution is two-fold. First it permits an efficient computation...

  1. Waste Heat Powered Ammonia Absorption Refrigeration Unit for LPG Recovery

    Energy Technology Data Exchange (ETDEWEB)

    Donald C, Energy Concepts Co.; Lauber, Eric, Western Refining Co.

    2008-06-20

    An emerging DOE-sponsored technology has been deployed. The technology recovers light ends from a catalytic reformer plant using waste heat powered ammonia absorption refrigeration. It is deployed at the 17,000 bpd Bloomfield, New Mexico refinery of Western Refining Company. The technology recovers approximately 50,000 barrels per year of liquefied petroleum gas that was formerly being flared. The elimination of the flare also reduces CO2 emissions by 17,000 tons per year, plus tons per year reductions in NOx, CO, and VOCs. The waste heat is supplied directly to the absorption unit from the Unifiner effluent. The added cooling of that stream relieves a bottleneck formerly present due to restricted availability of cooling water. The 350oF Unifiner effluent is cooled to 260oF. The catalytic reformer vent gas is directly chilled to minus 25oF, and the FCC column overhead reflux is chilled by 25oF glycol. Notwithstanding a substantial cost overrun and schedule slippage, this project can now be considered a success: it is both profitable and highly beneficial to the environment. The capabilities of directly-integrated waste-heat powered ammonia absorption refrigeration and their benefits to the refining industry have been demonstrated.

  2. Characterization of La/Fe/TiO₂ and Its Photocatalytic Performance in Ammonia Nitrogen Wastewater.

    Science.gov (United States)

    Luo, Xianping; Chen, Chunfei; Yang, Jing; Wang, Junyu; Yan, Qun; Shi, Huquan; Wang, Chunying

    2015-11-01

    La/Fe/TiO₂ composite photocatalysts were synthesized by Sol-Gel method and well characterized by powder X-ray diffraction (XRD), scanning electron microscopy (SEM), nitrogen-physical adsorption, and UV-Vis diffuse reflectance spectra (UV-Vis DRS). It is interesting that the doped catalysts were in anatase phase while the pure TiO₂ was in rutile phase. In addition, the composites possessed better physical chemical properties in photocatalytic activity than pure TiO₂: stronger visible-light-response ability, larger specific surface area, and more regular shape in morphology. The photodegradation results of ammonia nitrogen indicate that: the La/Fe/TiO₂ had higher catalytic activity to ammonia nitrogen waste water compared pure TiO₂ and the other single metal-doped TiO₂. pH 10 and 2 mmol/L H₂O₂ were all beneficial to the removal of ammonia nitrogen by La/Fe/TiO₂. However, the common inorganic ions of Cl(-), NO₃(-), SO₄(2-), HCO₃(-)/CO₃²(-), Na⁺, K⁺, Ca(2+) and Mg(2+) in water all inhibited the degradation of ammonia nitrogen. By balance calculation, at least 20% of ammonia nitrogen was converted to N₂ during the 64.6% removal efficiency of ammonia nitrogen.

  3. Characterization of La/Fe/TiO2 and Its Photocatalytic Performance in Ammonia Nitrogen Wastewater

    Science.gov (United States)

    Luo, Xianping; Chen, Chunfei; Yang, Jing; Wang, Junyu; Yan, Qun; Shi, Huquan; Wang, Chunying

    2015-01-01

    La/Fe/TiO2 composite photocatalysts were synthesized by Sol-Gel method and well characterized by powder X-ray diffraction (XRD), scanning electron microscopy (SEM), nitrogen-physical adsorption, and UV-Vis diffuse reflectance spectra (UV-Vis DRS). It is interesting that the doped catalysts were in anatase phase while the pure TiO2 was in rutile phase. In addition, the composites possessed better physical chemical properties in photocatalytic activity than pure TiO2: stronger visible-light-response ability, larger specific surface area, and more regular shape in morphology. The photodegradation results of ammonia nitrogen indicate that: the La/Fe/TiO2 had higher catalytic activity to ammonia nitrogen waste water compared pure TiO2 and the other single metal-doped TiO2. pH 10 and 2 mmol/L H2O2 were all beneficial to the removal of ammonia nitrogen by La/Fe/TiO2. However, the common inorganic ions of Cl−, NO3−, SO42−, HCO3−/CO32−, Na+, K+, Ca2+ and Mg2+ in water all inhibited the degradation of ammonia nitrogen. By balance calculation, at least 20% of ammonia nitrogen was converted to N2 during the 64.6% removal efficiency of ammonia nitrogen. PMID:26593929

  4. About sorption-catalytic air cleaning in premises for people habitation in megapolises

    Directory of Open Access Journals (Sweden)

    A.V. Cрechevichkin

    2011-01-01

    Full Text Available The basic sources of pollution of the air environment in megapolises, and also of internal atmosphere of premises for people habitation, in respect of their possible clearing by sorption-catalytic methods are systematized. Design and principle of action of the room sorption-catalytic three-chambered filter for clearing of turnaround air of a thermo premise of gaseous ammonia, hydrogen sulfide, carbon dioxide and organic substances are described.

  5. Synthesis, characterization and catalytic activity of CdO nanocrystals

    Energy Technology Data Exchange (ETDEWEB)

    Singh, G., E-mail: gsingh4us@yahoo.com [Department of Chemistry, D.D.U. Gorakhpur University, Gorakhpur 273009 (India); Kapoor, I.P.S.; Dubey, Reena; Srivastava, Pratibha [Department of Chemistry, D.D.U. Gorakhpur University, Gorakhpur 273009 (India)

    2011-02-15

    In this paper, we report the synthesis of nanocrystalline cadmium oxide (CdO) and its characterization by X-ray diffraction (XRD) and transmission electron microscopy (TEM). Its catalytic activity was investigated on the thermal decomposition of 1,2,5,7-tetranitro-1,3,5,7-tetraazacyclooctane (HMX), ammonium perchlorate (AP), hydroxyl terminated polybutadiene (HTPB) and composite solid propellants (CSPs) using thermogravimetric analysis (TG), simultaneous thermogravimerty and differential scanning calorimetry (TG-DSC) and ignition delay measurements. Kinetics of thermal decomposition of AP + CdO has also been investigated using model free (isoconversional) and model-fitting approaches which have been applied to data for isothermal TG decomposition. All these studies show enhancement in the rate of decomposition of AP, HTPB and CSPs but no effect on HMX. The burning rate of CSPs has also been found to be increased with CdO nanocrystals.

  6. Adsorption and decomposition of monopropellant molecule HAN on Pd(100) and Ir(100) surfaces: A DFT study

    Science.gov (United States)

    Banerjee, Sourav; Shetty, Sharath A.; Gowrav, M. N.; Oommen, Charlie; Bhattacharya, Atanu

    2016-11-01

    We have performed density functional theory calculations with the generalized gradient approximation to investigate the catalytic decomposition reactions of one of the most promising monopropellants, hydroxylammonium nitrate (HAN), on two catalytically active single crystal Pd(100) and Ir(100) surfaces, aiming at exploring different reaction pathways and reactivities of these two surfaces towards the catalytic decomposition of HAN. We find that the HAN molecule binds both the Pd(100) and Ir(100) surfaces molecularly in different orientations with respect to the surface. The HONO elimination is found to possess the lowest activation energy on the Pd(100) surface; whereas, NO2 elimination is predicted to show the lowest activation energy on the Ir(100) surface. Exothermicities associated with different reaction steps are also discussed. This is the first theoretical report on the catalytic decomposition reactions of the HAN molecule on the single crystal Pd(100) and the Ir(100) surfaces using the periodic DFT calculations.

  7. DETERMINATION OF AMMONIA IN EAR-LOBE CAPILLARY BLOOD IS AN ALTERNATIVE TO ARTERIAL BLOOD AMMONIA

    NARCIS (Netherlands)

    HUIZENGA, [No Value; GIPS, CH; CONN, HO; JANSEN, PLM

    1995-01-01

    Blood ammonia determination is a laboratory test to diagnose hepatic encephalopathy. Arterial blood is superior to peripheral venous blood ammonia because of ammonia metabolism in muscle. We have compared capillary with arterial whole blood ammonia as capillary sampling is an attractive alternative.

  8. Niche specialization of terrestrial archaeal ammonia oxidizers

    OpenAIRE

    Gubry-Rangin, Cécile; Hai, Brigitte; Quince, Christopher; Engel, Marion; Thomson, Bruce C.; James, Phillip; Schloter, Michael; Robert I. Griffiths; Prosser, James I.; Nicol, Graeme W.

    2011-01-01

    Soil pH is a major determinant of microbial ecosystem processes and potentially a major driver of evolution, adaptation, and diversity of ammonia oxidizers, which control soil nitrification. Archaea are major components of soil microbial communities and contribute significantly to ammonia oxidation in some soils. To determine whether pH drives evolutionary adaptation and community structure of soil archaeal ammonia oxidizers, sequences of amoA, a key functional gene of ammonia oxidation, were...

  9. 46 CFR 154.1760 - Liquid ammonia.

    Science.gov (United States)

    2010-10-01

    ... 46 Shipping 5 2010-10-01 2010-10-01 false Liquid ammonia. 154.1760 Section 154.1760 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) CERTAIN BULK DANGEROUS CARGOES SAFETY STANDARDS FOR....1760 Liquid ammonia. The master shall ensure that no person sprays liquid ammonia into a cargo...

  10. 27 CFR 21.96 - Ammonia, aqueous.

    Science.gov (United States)

    2010-04-01

    ... 27 Alcohol, Tobacco Products and Firearms 1 2010-04-01 2010-04-01 false Ammonia, aqueous. 21.96 Section 21.96 Alcohol, Tobacco Products and Firearms ALCOHOL AND TOBACCO TAX AND TRADE BUREAU, DEPARTMENT... Ammonia, aqueous. (a) Alkalinity. Strongly alkaline to litmus. (b) Ammonia content. 27 to 30 percent...

  11. Parameter Optimization on Experimental Study to Reduce Ammonia Escape in CO2 Absorption by Ammonia Scrubbing

    Institute of Scientific and Technical Information of China (English)

    Hao Leng; Jianmin Gao; Mingyue He; Min Xie; Qian Du; Rui Sun; Shaohua Wu

    2016-01-01

    In order to research ammonia escape in CO2 absorption by ammonia scrubbing, ammonia escape was studied in CO2 absorption process using the bubbling reactor in different conditions as gas flow rate, CO2 ratio, absorbent temperature and ammonia concentration and quantity of escaped ammonia was measured by chemical titration. The results indicated that, the amount of ammonia escape can be around 20% of original amount in 90 min and the escaped amount will increase with the rise of gas flow rate, absorbent temperature, concentration of ammonia while decrease as CO2 ratio goes up. Through the analysis of the law of ammonia escape, at the same time, combined with ammonia escape and the influence of the relationship between the CO2 absorption efficiency, reducing ammonia escape working condition parameter optimization is given.

  12. Effect of samarium on methanation resistance of activated carbon supported ruthenium catalyst for ammonia synthesis

    Institute of Scientific and Technical Information of China (English)

    周春晖; 祝一锋; 刘化章

    2010-01-01

    The effects of samarium(Sm) on carbon-methanation and catalytic activity of the Ba-Ru-K/AC (active carbon) catalyst for ammonia synthesis were investigated. The addition of samarium improved significantly the activity and stability of the catalyst. The results of temperature-programmed desorption (H2-TPD) and in-situ-TPSR FTIR indicated that samarium impeded the adsorption of hydrogen on the catalyst surface, thus leading to the high catalytic activity and resistance to carbon-methanation. XRD patterns reve...

  13. Inhibiting Wet Oxidation of Ammonia

    Science.gov (United States)

    Onisko, D. B. L.

    1985-01-01

    Simple modification of wet-oxidation process for treating organicwaste reduces loss of fixed nitrogen, potentially valuable byproduct of process. Addition of sufficient sulfuric acid to maintain reaction pH below 3 greatly reduces oxidation of ammonia to free nitrogen. No equipment modification required.

  14. Forthcoming Oversupply for Synthetic Ammonia

    Institute of Scientific and Technical Information of China (English)

    Zhang Zhantong

    2007-01-01

    @@ Stable output increase The total capacity of synthetic ammonia in China is 52.0 million t/a today.There are around 540 producers mainly located in Shandong, Shanxi, Hebei,Henan, Jiangsu and Sichuan provinces.The cumulative capacity in Shandong province ranks the highest, accounting for 14.6% of the national total.

  15. Hydrogen production using ammonia borane

    Science.gov (United States)

    Hamilton, Charles W; Baker, R. Thomas; Semelsberger, Troy A; Shrestha, Roshan P

    2013-12-24

    Hydrogen ("H.sub.2") is produced when ammonia borane reacts with a catalyst complex of the formula L.sub.nM-X wherein M is a base metal such as iron, X is an anionic nitrogen- or phosphorus-based ligand or hydride, and L is a neutral ancillary ligand that is a neutral monodentate or polydentate ligand.

  16. Ammonia in power plant emission

    Science.gov (United States)

    Hammerich, Mads; Henningsen, J. O.; Olafsson, Ari

    1990-08-01

    Ammonia monitoring is needed in most schemes for denitrification of power plant emission. In the PALAMON system we use a 500 MHz tunable, single mode, single line, CO2 laser as light source for a low pressure, high temperature, photoacoustic cell. With this cell we can resolve the sR(5,O) line of the ammonia spectrum, and suppress the interfering C02(9R30) absorption line down to a lppm NH3 detection limit. The validity of the measured ammonia concentrations is strongly dependent on details of the sampling system and on the reliability of the calibration routines. In particular calibration with certified mixtures of NH3:N2 has proved insufficient due to the multiple and long time constants caused by adsorption of ammonia to different materials in the system. Presence of water vapor in the gas greatly reduces these time constants. Therefore a number of methods for simple production of moist calibration gases from macroscopic amounts of NH3 are applied. The calibrations are translated to response from an easily managable absorber in order to allow automated recalibration of the photoacoustic response. Data from a field test of the system, and calibration data will be presented.

  17. [Influence of ammonia on leaching behaviors of incineration fly ash and its geochemical modeling].

    Science.gov (United States)

    Guan, Zhen-Zhen; Chen, De-Zhen; Thomas, Astrup

    2013-06-01

    Incineration fly ash could be contaminated with NH3 that was slipped from the ammonia-based selective non-catalytic reduction(SNCR) process and from evaporation of municipal solid wastes' leachate involved in the wastes. This research was conducted to investigate the impacts of ammonia on leaching of dissolved organic carbon (DOC) and metals from incineration fly ash in the pH range of 3.66-12.44 with an active ammonia spike. A geochemical modeling software Visual MINTEQ was adopted to calculate the chemical speciation of metals under the leaching conditions to reveal the mechanism behind the impacts. It was proved that at pH > 9, the leaching of DOC increased significantly in the presence of high concentrations of ammonia (> or = 1 357 mg x L(-1)), but there was little effect when the ammonia level in eluates was not higher than 537 mg x L(-1). At pH or = 3 253 mg x L(-1)) mobilized Cd, Cu, Ni and Zn significantly due to the formation of soluble metal-ammonia complexes, and the leaching rates reached their peaks at pH around 9; however, ammonia had little impacts on Al and Pb leaching within this pH range. At pH > 12, for Cd, Cu, Ni and Zn, their leaching species were predominantly in the form of hydroxide complexes. Under the ammonia concentration of 3253 mg x L(-1), the Visual MINTEQ modeling results were compared with the experimental data, and it was proved that the leaching of Al, Pb and Zn was mainly controlled by precipitation/dissolution modeling, while Cd, Cu and Ni were controlled by precipitation/dissolution and surface complexation/precipitation processes; Visual MINTEQ modeling could well describe the leaching behaviors of Al, Cu, Pb and Zn from incineration fly ash. PMID:23947071

  18. Nitrate reduction to nitrite, nitric oxide and ammonia by gut bacteria under physiological conditions.

    Directory of Open Access Journals (Sweden)

    Mauro Tiso

    Full Text Available The biological nitrogen cycle involves step-wise reduction of nitrogen oxides to ammonium salts and oxidation of ammonia back to nitrites and nitrates by plants and bacteria. Neither process has been thought to have relevance to mammalian physiology; however in recent years the salivary bacterial reduction of nitrate to nitrite has been recognized as an important metabolic conversion in humans. Several enteric bacteria have also shown the ability of catalytic reduction of nitrate to ammonia via nitrite during dissimilatory respiration; however, the importance of this pathway in bacterial species colonizing the human intestine has been little studied. We measured nitrite, nitric oxide (NO and ammonia formation in cultures of Escherichia coli, Lactobacillus and Bifidobacterium species grown at different sodium nitrate concentrations and oxygen levels. We found that the presence of 5 mM nitrate provided a growth benefit and induced both nitrite and ammonia generation in E.coli and L.plantarum bacteria grown at oxygen concentrations compatible with the content in the gastrointestinal tract. Nitrite and ammonia accumulated in the growth medium when at least 2.5 mM nitrate was present. Time-course curves suggest that nitrate is first converted to nitrite and subsequently to ammonia. Strains of L.rhamnosus, L.acidophilus and B.longum infantis grown with nitrate produced minor changes in nitrite or ammonia levels in the cultures. However, when supplied with exogenous nitrite, NO gas was readily produced independently of added nitrate. Bacterial production of lactic acid causes medium acidification that in turn generates NO by non-enzymatic nitrite reduction. In contrast, nitrite was converted to NO by E.coli cultures even at neutral pH. We suggest that the bacterial nitrate reduction to ammonia, as well as the related NO formation in the gut, could be an important aspect of the overall mammalian nitrate/nitrite/NO metabolism and is yet another way in

  19. Decomposition of semigroup algebras

    CERN Document Server

    Boehm, Janko; Nitsche, Max Joachim

    2011-01-01

    Let A \\subseteq B be cancellative abelian semigroups, and let R be an integral domain. We show that the semigroup ring R[B] can be decomposed, as an R[A]-module, into a direct sum of R[A]-submodules of the quotient ring of R[A]. In the case of a finite extension of positive affine semigroup rings we obtain an algorithm computing the decomposition. When R[A] is a polynomial ring over a field we explain how to compute many ring-theoretic properties of R[B] in terms of this decomposition. In particular we obtain a fast algorithm to compute the Castelnuovo-Mumford regularity of homogeneous semigroup rings. As an application we confirm the Eisenbud-Goto conjecture in a range of new cases. Our algorithms are implemented in the Macaulay2 package MonomialAlgebras.

  20. Decompositions of Proper Scores

    CERN Document Server

    Bröcker, Jochen

    2008-01-01

    Scoring rules are an important tool for evaluating the performance of probabilistic forecasts. A popular example is the Brier score, which allows for a decomposition into terms related to the sharpness (or information content) and to the reliability of the forecast. This feature renders the Brier score a very intuitive measure of forecast quality. In this paper, it is demonstrated that all strictly proper scoring rules allow for a similar decomposition into reliability and sharpness related terms. This finding underpins the importance of proper scores and yields further credence to the practice of measuring forecast quality by proper scores. Furthermore, the effect of averaging multiple probabilistic forecasts on the score is discussed. It is well known that the Brier score of a mixture of several forecasts is never worse that the average score of the individual forecasts. This property hinges on the convexity of the Brier score, a property not universal among proper scores. Arguably, this phenomenon portends...

  1. Transcriptional Response of the Archaeal Ammonia Oxidizer Nitrosopumilus maritimus to Low and Environmentally Relevant Ammonia Concentrations

    OpenAIRE

    Nakagawa, Tatsunori; Stahl, David A.

    2013-01-01

    The ability of chemoautotrophic ammonia-oxidizing archaea to compete for ammonia among marine microorganisms at low ambient concentrations has been in part attributed to their extremely high affinity for ammonia, but as yet there is no mechanistic understanding of supporting metabolism. We examined transcription of selected genes for anabolic functions (CO2 fixation, ammonia transport, and cell wall synthesis) and a central catabolic function (ammonia oxidation) in the thaumarchaeon Nitrosopu...

  2. Thermic decomposition of biphenyl

    International Nuclear Information System (INIS)

    Liquid and vapour phase pyrolysis of very pure biphenyl obtained by methods described in the text was carried out at 400 C in sealed ampoules, the fraction transformed being always less than 0.1 per cent. The main products were hydrogen, benzene, terphenyls, and a deposit of polyphenyls strongly adhering to the walls. Small quantities of the lower aliphatic hydrocarbons were also found. The variation of the yields of these products with a) the pyrolysis time, b) the state (gas or liquid) of the biphenyl, and c) the pressure of the vapour was measured. Varying the area and nature of the walls showed that in the absence of a liquid phase, the pyrolytic decomposition takes place in the adsorbed layer, and that metallic walls promote the reaction more actively than do those of glass (pyrex or silica). A mechanism is proposed to explain the results pertaining to this decomposition in the adsorbed phase. The adsorption seems to obey a Langmuir isotherm, and the chemical act which determines the overall rate of decomposition is unimolecular. (author)

  3. Using advanced electron microscopy for the characterization of catalytic materials

    Science.gov (United States)

    Pyrz, William D.

    -corrected electron microscopy was used to systematically examine, atomic column by atomic column, the effect of elemental substitution on the long-range crystalline order, atomic coordinates, and site occupancies of the various formulations such that trends could be developed linking these properties to catalytic yields. To accomplish this task, an algorithm was developed that enabled the direct extraction of atomic coordinates and site occupancies from high-angle annular dark-field (HAADF) images to within 1% and 15% uncertainty, respectively. Furthermore, this general method could be applied to various crystalline systems and may dramatically improve the quality of initial structural models used in Rietveld refinements. Improvement in the quality of starting models may increase the structural and chemical complexity of inorganic structures that can be solved by using "powder methods" alone. In addition to the development of these trends, HAADF analyses also revealed the presence of coherent compositional miscibility gaps, rotational twin domains, and structural intergrowths in the complex Mo-V-M-O oxide system. Other catalytic systems that are addressed in this dissertation include Pd, Ag, and bimetallic Pd-Ag catalysts for the selective hydrogenation of acetylene in excess ethylene, alkali and alkaline earth promoted Ru catalysts for the production of clean hydrogen through the decomposition of ammonia, the production of Pt nanoparticles using dendrimer templates, and Pt-Re bimetallic catalysts for the conversion of glycerol to hydrocarbons and syn gas. In each of these studies, electron microscopy was used as a complimentary tool to synthetic and reaction studies to better understand interactions between the nanoparticles and the support/template, to determine the effect of adding various promoters, or to understand the nanoscale structural and chemical changes associated with the formation of bimetallic nanoparticles. A final area addressed in this dissertation is the

  4. Mechanism of photo catalytic degradation of Brilliant Blue colorant in water suspension with TiO{sub 2} catalyst

    Energy Technology Data Exchange (ETDEWEB)

    Cortes, J.A.; Gonzalez-Hernandez, J. [CIMAV, Complejo Industrial Chihuahua, 3110, Chihuahua (Mexico); Perez-Robles, J.F.; Vorobiev, P.; Vorobiev, Y.V.; Garcia, A.G. [Unidad Queretaro del CINVESTAV-IPN, Libramiento Norponiente 2000, 76230 Queretaro (Mexico)

    2011-06-15

    Water purification by photo catalytic decomposition of Brilliant Blue colorant in water suspension was studied. This work presents experimental and theoretical results in which the mechanism is discussed of decomposition of an organic colorant's molecule. In theoretical part, a calculation of the energy levels of the molecule and its parts derived in decomposition process based on modified FEMO modeling confirm the mechanism proposed (copyright 2011 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  5. Production of filamentous carbon and H{sub 2} by solarthermal catalytic cracking of CH{sub 4}

    Energy Technology Data Exchange (ETDEWEB)

    Kirillov, V.; Kuvshinov, G. [Boreskov Inst. of Catalysis (Russian Federation); Reller, A. [Hamburg Univ., Hamburg (Germany); Steinfeld, A. [Paul Scherrer Inst. (PSI), Villigen (Switzerland)

    1997-06-01

    The catalytic thermal decomposition of methane has been experimentally studied using high-temperature solar process heat. Nickel catalyst particles, fluidized in methane, were directly irradiated at the PSI solar furnace. Carbon deposition consisted of randomly interlaced filaments that grew as fibers and hollow nanotubes (of approx. 30 nm diameter) originating at each catalytic particle. (author) 4 figs., 7 refs.

  6. Sulfate Promoted Zirconia as Promising Alkali-Resistant Support for Catalytic NOx Removal

    DEFF Research Database (Denmark)

    Due-Hansen, Johannes; Kustov, Arkadii; Christensen, Claus H.;

    The use of bio-fuels as alternatives to traditional fossil fuels has attracted much attention recent years since bio-fuels belong to a family of renewable types of energy sources and do not contribute to the green-house effect. Selective catalytic reduction (SCR) of NOx with ammonia as reductant...

  7. Sulfated Zirconia as Alkali-Resistant Support for Catalytic NOx Removal

    DEFF Research Database (Denmark)

    The use of bio-fuels as alternatives to traditional fossil fuels has attracted much attention recent years since bio-fuels belong to a family of renewable types of energy sources and do not contribute to the green-house effect. Selective catalytic reduction (SCR) of NOx with ammonia as reductant...

  8. Catalytic distillation structure

    Science.gov (United States)

    Smith, Jr., Lawrence A.

    1984-01-01

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

  9. Catalytic combustor for hydrogen

    Energy Technology Data Exchange (ETDEWEB)

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

    1982-01-01

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

  10. Photocatalytic decomposition of cortisone acetate in aqueous solution.

    Science.gov (United States)

    Romão, Joana Sobral; Hamdy, Mohamed S; Mul, Guido; Baltrusaitis, Jonas

    2015-01-23

    The photocatalytic decomposition of cortisone 21-acetate (CA), a model compound for the commonly used steroid, cortisone, was studied. CA was photocatalytically decomposed in a slurry reactor with the initial rates between 0.11 and 0.46 mg L(-1)min(-1) at 10 mg L(-1) concentration, using the following heterogeneous photocatalysts in decreasing order of their catalytic activity: ZnO>Evonik TiO2 P25>Hombikat TiO2>WO3. Due to the lack of ZnO stability in aqueous solutions, TiO2 P25 was chosen for further experiments. The decomposition reaction was found to be pseudo-first order and the rate constant decreased as a function of increasing initial CA concentration. Changing the initial pH of the CA solution did not affect the reaction rate significantly. The decomposition reaction in the presence of the oxidizing sacrificial agent sodium persulfate showed an observed decomposition rate constant of 0.004 min(-1), lower than that obtained for TiO2 P25 (0.040 min(-1)). The highest photocatalytic degradation rate constant was obtained combining both TiO2 P25 and S2O8(2-) (0.071 min(-1)) showing a synergistic effect. No reactive intermediates were detected using LC-MS showing fast photocatalytic decomposition kinetics of CA. PMID:24953705

  11. Adaptive Integrand Decomposition

    CERN Document Server

    Mastrolia, Pierpaolo; Primo, Amedeo; Bobadilla, William J Torres

    2016-01-01

    We present a simplified variant of the integrand reduction algorithm for multiloop scattering amplitudes in $d = 4 - 2\\epsilon$ dimensions, which exploits the decomposition of the integration momenta in parallel and orthogonal subspaces, $d=d_\\parallel+d_\\perp$, where $d_\\parallel$ is the dimension of the space spanned by the legs of the diagrams. We discuss the advantages of a lighter polynomial division algorithm and how the orthogonality relations for Gegenbauer polynomilas can be suitably used for carrying out the integration of the irreducible monomials, which eliminates spurious integrals. Applications to one- and two-loop integrals, for arbitrary kinematics, are discussed.

  12. Ammonia abatement by slurry acidification

    DEFF Research Database (Denmark)

    Petersen, Søren O.; Hutchings, Nicholas John; Hafner, Sasha;

    2016-01-01

    Livestock production systems can be major sources of trace gases including ammonia (NH3), the greenhouse gases methane (CH4) and nitrous oxide (N2O), and odorous compounds such as hydrogen sulphide (H2S). Short-term campaigns have indicated that acidification of livestock slurry during in...... generally high. It was concluded that the contribution from floors to NH3 emissions was effect on N2O emissions was observed. The effect...

  13. Ammonia Production, Excretion, Toxicity, and Defense in Fish: A Review

    OpenAIRE

    Yuen K Ip; Chew, Shit F.

    2010-01-01

    Many fishes are ammonotelic but some species can detoxify ammonia to glutamine or urea. Certain fish species can accumulate high levels of ammonia in the brain or defense against ammonia toxicity by enhancing the effectiveness of ammonia excretion through active NH 4 + transport, manipulation of ambient pH, or reduction in ammonia permeability through the branchial and cutaneous epithelia. Recent reports on ammonia toxicity in mammalian brain reveal the importance of permeation of ammonia thr...

  14. Fiber-Optic Ammonia Sensors

    Science.gov (United States)

    Carter, Michael T.

    2003-01-01

    Reversible, colorimetric fiber-optic sensors are undergoing development for use in measuring concentrations of ammonia in air at levels relevant to human health [0 to 50 parts per million (ppm)]. A sensor of this type includes an optical fiber that has been modified by replacing a portion of its cladding with a polymer coat that contains a dye that reacts reversibly with ammonia and changes color when it does so. The change in color is measured as a change in the amount of light transmitted from one end of the fiber to the other. Responses are reversible and proportional to the concentration of ammonia over the range from 9 to 175 ppm and in some cases the range of reversibility extends up to 270 ppm. The characteristic time for the response of a sensor to rise from 10 to 90 percent of full scale is about 25 seconds. These sensors are fully operational in pure carbon dioxide and are not adversely affected by humidity. This work was done by Michael T. Carter

  15. Planar waveguide sensor of ammonia

    Science.gov (United States)

    Rogoziński, Roman; Tyszkiewicz, Cuma; Karasiński, Paweł; Izydorczyk, Weronika

    2015-12-01

    The paper presents the concept of forming ammonia sensor based on a planar waveguide structure. It is an amplitude sensor produced on the basis of the multimode waveguide. The technological base for this kind of structure is the ion exchange method and the sol-gel method. The planar multimode waveguide of channel type is produced in glass substrate (soda-lime glass of Menzel-Glaser company) by the selective Ag+↔Na+ ion exchange. On the surface of the glass substrate a porous (~40%) silica layer is produced by the sol-gel method. This layer is sensitized to the presence of ammonia in the surrounding atmosphere by impregnation with Bromocresol Purple (BCP) dye. Therefore it constitutes a sensor layer. Spectrophotometric tests carried out showed about 50% reduction of cross-transmission changes of such sensor layer for a wave λ=593 nm caused by the presence of 25% ammonia water vapor in its ambience. The radiation source used in this type of sensor structure is a light emitting diode LED. The gradient channel waveguide is designed for frontal connection (optical glue) with a standard multimode telecommunications waveguide 62.5/125μm.

  16. Thermal decomposition of lutetium propionate

    DEFF Research Database (Denmark)

    Grivel, Jean-Claude

    2010-01-01

    The thermal decomposition of lutetium(III) propionate monohydrate (Lu(C2H5CO2)3·H2O) in argon was studied by means of thermogravimetry, differential thermal analysis, IR-spectroscopy and X-ray diffraction. Dehydration takes place around 90 °C. It is followed by the decomposition of the anhydrous...... °C. Full conversion to Lu2O3 is achieved at about 1000 °C. Whereas the temperatures and solid reaction products of the first two decomposition steps are similar to those previously reported for the thermal decomposition of lanthanum(III) propionate monohydrate, the final decomposition...... of the oxycarbonate to the rare-earth oxide proceeds in a different way, which is here reminiscent of the thermal decomposition path of Lu(C3H5O2)·2CO(NH2)2·2H2O...

  17. Information Decomposition on Structured Space

    OpenAIRE

    Sugiyama, Mahito; Nakahara, Hiroyuki; Tsuda, Koji

    2016-01-01

    We build information geometry for a partially ordered set of variables and define the orthogonal decomposition of information theoretic quantities. The natural connection between information geometry and order theory leads to efficient decomposition algorithms. This generalization of Amari's seminal work on hierarchical decomposition of probability distributions on event combinations enables us to analyze high-order statistical interactions arising in neuroscience, biology, and machine learning.

  18. Modeling N2O Reduction and Decomposition in a Circulating Fluidized bed Boiler

    DEFF Research Database (Denmark)

    Johnsson, Jan Erik; Åmand, Lars-Erik; Dam-Johansen, Kim;

    1996-01-01

    The N2O concentration was measured in a circulating fluidized bed boiler of commercial size. Kinetics for N2O reduction by char and catalytic reduction and decomposition over bed material from the combustor were determined in a laboratory fixed bed reactor. The destruction rate of N2O in the comb...

  19. Selective reduction of NO by photo-SCR with ammonia in an annular fixed-film photoreactor

    Institute of Scientific and Technical Information of China (English)

    YiangChen CHOU; Young KU

    2012-01-01

    Gaseous NO was photocatalytically reduced at room temperature by photo-assisted selective catalytic reduction (photo-SCR) with ammonia over TiO2 in this study. NO reduction efficiency and N2 selectivity were determined from gases composition at the outlet stream of photoreactor. Effect of operating conditions, e.g. light intensity and inlet concentrations of ammonia and oxygen, on the NO reduction efficiency and N2 selectivity were discussed to determine the feasible operating condition for photocatalytic reduction of NO. Experimental results showed that selective catalytic reduction of NO with ammonia over TiO2 in the presence of oxygen was a spontaneous reaction in dark. The photoirradiation on the TiO2 surface caused remarkable photocatalytic reduction of NO to form N2, NO2, and N20 under 254 nm UV illuminations, while almost 90% of N2 selectivity was achieved in this study. The ammonia and oxygen molecules played the roles of reductant and oxidant for NO reduction and active sites regeneration, respectively. The reduction of NO was found to be increased with the increase of inlet ammonia and oxygen concentrations until specific concentrations because of the limited active sites on the surface of TiO2. The kinetic model proposed in this study can be used to reasonably describe the reaction mechanism of photo-SCR.

  20. Exploring the decomposition pathways of iron asymmetric transfer hydrogenation catalysts.

    Science.gov (United States)

    Lagaditis, Paraskevi O; Sues, Peter E; Lough, Alan J; Morris, Robert H

    2015-07-21

    Our group has developed a series of iron-based asymmetric transfer hydrogenation (ATH) catalysts for the reduction of polar double bonds. The activation of the precatalysts as well as the catalytic mechanism have been thoroughly investigated, but the decomposition pathways of these systems are poorly understood. Herein, we report a study of the deactivation pathways for an iron ATH catalyst under catalytically relevant conditions. The decomposition pathways were examined using experimental techniques and density functional theory (DFT) calculations. The major decomposition products that formed, Fe(CO)((Et)2PCH2CH2CHCHNCH2CH2P(Et)2) (3a) and Fe(CO)((Et)2PCH2CH2C(Ph)C(Ph)NCH2CH2P(Et)2) (3b), had two amido donors as well as a C=C bond on the diamine backbone of the tetradentate ligand. These species were identified by NMR studies and one was isolated as a bimetallic complex with Ru(II)Cp*. Two minor iron hydride species also formed concurrently with 3a, as determined by NMR studies, one of which was isolated and contained a fully saturated ligand as well as a hydride ligand. None of the compounds that were isolated were found to be active ATH catalysts. PMID:25373607

  1. Ammonia Process by Pressure Swing Adsorption

    Energy Technology Data Exchange (ETDEWEB)

    Dr Felix Jegede

    2010-12-27

    The overall objective of the project is to design, develop and demonstrate a technically feasible and commercially viable system to produce ammonia along with recovery of the products by adsorption separation methods and significantly decrease the energy requirement in ammonia production. This is achieved through a significantly more efficient ammonia psa recovery system. The new ammonia recovery system receives the reactor effluents and achieves complete ammonia recovery, (which completely eliminates the energy intensive refrigeration and condensation system currently used in ammonia production). It also recovers the unused reactants and recycles them back to the reactor, free of potential reactor contaminants, and without the need for re-compression and re-heat of recycle stream thereby further saving more energy. The result is a significantly lower energy consumption, along with capital cost savings.

  2. A theoretical study on the catalytic effect of nanoparticle confined in carbon nanotube

    Science.gov (United States)

    Qin, Wu; Li, Xin

    2011-01-01

    We investigated the catalytic effect of CuO nanoparticles confined in carbon nanotubes using molecular dynamics simulations and density functional theory calculations. Ozone decomposition and hydroxyl radical generation were used as the probe reactions to investigate the catalytic behavior of catalyst. The effects of the confined environment of carbon nanotubes induced more reactants into the channel. Interface interactions between reactants and CuO nanoparticles in the channel and charge transfer accelerated the decomposition of ozone into oxygen molecule and atomic oxygen species. The atomic oxygen species then interacted to water molecule to generate hydroxyl radicals, which were truly identified by electron paramagnetic resonance (EPR) technique.

  3. Ammonia emission from crop residues : quantification of ammonia volatilization based on crop residue properties

    NARCIS (Netherlands)

    Ruijter, de F.J.; Huijsmans, J.F.M.

    2012-01-01

    This paper gives an overview of available literature data on ammonia volatilization from crop residues. From these data, a relation is derived for the ammonia emission depending on the N-content of crop residue.

  4. Autotrophic ammonia oxidation by soil thaumarchaea

    OpenAIRE

    Zhang, Li-Mei; Offre, Pierre R.; He, Ji-Zheng; Verhamme, Daniel T.; Nicol, Graeme W.; Prosser, James I.

    2010-01-01

    Nitrification plays a central role in the global nitrogen cycle and is responsible for significant losses of nitrogen fertilizer, atmospheric pollution by the greenhouse gas nitrous oxide, and nitrate pollution of groundwaters. Ammonia oxidation, the first step in nitrification, was thought to be performed by autotrophic bacteria until the recent discovery of archaeal ammonia oxidizers. Autotrophic archaeal ammonia oxidizers have been cultivated from marine and thermal spring environments, bu...

  5. Exhaust purification with on-board ammonia production

    Science.gov (United States)

    Robel, Wade J.; Driscoll, James J.; Coleman, Gerald N.; Knox, Kevin J.

    2009-06-30

    A power source is provided for use with selective catalytic reduction systems for exhaust-gas purification. The power source includes a first cylinder group with a first air-intake passage and a first exhaust passage, and a second cylinder group with a second air-intake passage and a second exhaust passage. The second air-intake passage is fluidly isolated from the first air-intake passage. A fuel-supply device may be configured to supply fuel into the first exhaust passage, and a catalyst may be disposed downstream of the fuel-supply device to convert at least a portion of the exhaust stream in the first exhaust passage into ammonia.

  6. Catalytic distillation process

    Science.gov (United States)

    Smith, Jr., Lawrence A.

    1982-01-01

    A method for conducting chemical reactions and fractionation of the reaction mixture comprising feeding reactants to a distillation column reactor into a feed zone and concurrently contacting the reactants with a fixed bed catalytic packing to concurrently carry out the reaction and fractionate the reaction mixture. For example, a method for preparing methyl tertiary butyl ether in high purity from a mixed feed stream of isobutene and normal butene comprising feeding the mixed feed stream to a distillation column reactor into a feed zone at the lower end of a distillation reaction zone, and methanol into the upper end of said distillation reaction zone, which is packed with a properly supported cationic ion exchange resin, contacting the C.sub.4 feed and methanol with the catalytic distillation packing to react methanol and isobutene, and concurrently fractionating the ether from the column below the catalytic zone and removing normal butene overhead above the catalytic zone.

  7. Catalytic Functions of Standards

    NARCIS (Netherlands)

    K. Blind (Knut)

    2009-01-01

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

  8. Cylinder supplied ammonia scrubber testing in IDMS

    International Nuclear Information System (INIS)

    This report summarizes the results of the off-line testing the Integrated DWPF Melter System (IDMS) ammonia scrubbers using ammonia supplied from cylinders. Three additional tests with ammonia are planned to verify the data collected during off-line testing. Operation of the ammonia scrubber during IDMS SRAT and SME processing will be completed during the next IDMS run. The Sludge Receipt and Adjustment Tank (SRAT) and Slurry Mix Evaporator (SME) scrubbers were successful in removing ammonia from the vapor stream to achieve ammonia vapor concentrations far below the 10 ppM vapor exit design basis. In most of the tests, the ammonia concentration in the vapor exit was lower than the detection limit of the analyzers so results are generally reported as <0.05 parts per million (ppM). During SRAT scrubber testing, the ammonia concentration was no higher than 2 ppM and during SME testing the ammonia concentration was no higher than 0.05 m

  9. Tetraammineplatinum(II dichloride ammonia tetrasolvate

    Directory of Open Access Journals (Sweden)

    Tobias Grassl

    2014-07-01

    Full Text Available The title compound, [Pt(NH34]Cl2·4NH3, was crystallized in liquid ammonia from the salt PtCl2. The platinum cation is coordinated by four ammonia molecules, forming a square-planar complex. The chloride anions are surrounded by nine ammonia molecules, either bound within the platinum complex or solvent molecules. The solvent ammonia molecules are packed in such a way that an extended network of N—H...N and N—H...Cl hydrogen bonds is formed. The structure is isotypic with [Pd(NH34]Cl2·4NH3 [Grassl & Korber (2014. Acta Cryst. E70, i32].

  10. Ammonia and urea permeability of mammalian aquaporins

    DEFF Research Database (Denmark)

    Litman, Thomas; Søgaard, Rikke; Zeuthen, Thomas

    2009-01-01

    The human aquaporins,AQP3,AQP7, AQP8,AQP9, and possibly AQP10, are permeable to ammonia, and AQP7, AQP9, and possibly AQP3, are permeable to urea. In humans, these aquaporins supplement the ammonia transport of the Rhesus (Rh) proteins and the urea transporters (UTs). The mechanism by which...... and 9 are found together with Rh proteins in cells exposed to portal blood coming from the intestine. In the kidney, AQP3 might participate in the excretion of NH(4) (+) in the collecting duct. The interplay between the ammonia-permeable aquaporins and the other types of ammonia- and urea...

  11. Erbium hydride decomposition kinetics.

    Energy Technology Data Exchange (ETDEWEB)

    Ferrizz, Robert Matthew

    2006-11-01

    Thermal desorption spectroscopy (TDS) is used to study the decomposition kinetics of erbium hydride thin films. The TDS results presented in this report are analyzed quantitatively using Redhead's method to yield kinetic parameters (E{sub A} {approx} 54.2 kcal/mol), which are then utilized to predict hydrogen outgassing in vacuum for a variety of thermal treatments. Interestingly, it was found that the activation energy for desorption can vary by more than 7 kcal/mol (0.30 eV) for seemingly similar samples. In addition, small amounts of less-stable hydrogen were observed for all erbium dihydride films. A detailed explanation of several approaches for analyzing thermal desorption spectra to obtain kinetic information is included as an appendix.

  12. Autonomous Gaussian Decomposition

    CERN Document Server

    Lindner, Robert R; Murray, Claire E; Stanimirović, Snežana; Babler, Brian L; Heiles, Carl; Hennebelle, Patrick; Goss, W M; Dickey, John

    2014-01-01

    We present a new algorithm, named Autonomous Gaussian Decomposition (AGD), for automatically decomposing spectra into Gaussian components. AGD uses derivative spectroscopy and machine learning to provide optimized guesses for the number of Gaussian components in the data, and also their locations, widths, and amplitudes. We test AGD and find that it produces results comparable to human-derived solutions on 21cm absorption spectra from the 21cm SPectral line Observations of Neutral Gas with the EVLA (21-SPONGE) survey. We use AGD with Monte Carlo methods to derive the HI line completeness as a function of peak optical depth and velocity width for the 21-SPONGE data, and also show that the results of AGD are stable against varying observational noise intensity. The autonomy and computational efficiency of the method over traditional manual Gaussian fits allow for truly unbiased comparisons between observations and simulations, and for the ability to scale up and interpret the very large data volumes from the up...

  13. RuCu nanoparticles supported on graphene: A highly efficient catalyst for hydrolysis of ammonia borane

    Energy Technology Data Exchange (ETDEWEB)

    Cao, Nan; Hu, Kai [College of Chemistry and Molecular Sciences, Wuhan University, Wuhan, Hubei 430072 (China); Luo, Wei, E-mail: wluo@whu.edu.cn [College of Chemistry and Molecular Sciences, Wuhan University, Wuhan, Hubei 430072 (China); Suzhou Institute of Wuhan University, Suzhou, Jiangsu, 215123 (China); Cheng, Gongzhen, E-mail: gzcheng@whu.edu.cn [College of Chemistry and Molecular Sciences, Wuhan University, Wuhan, Hubei 430072 (China)

    2014-03-25

    Graphical abstract: Well dispersed RuCu/graphene nanoparticles exerted satisfied catalytic activity and recycle stability towards the hydrolysis of ammonia borane. Highlights: • One-step in situ synthesis of graphene supported RuCu NPs. • The catalysts exhibit excellent catalytic activity toward hydrolysis of AB. • Graphene supported NPs exhibit the highest catalytic activity. -- Abstract: Well dispersed RuCu nanoparticles (NPs) supported on graphene were in situ synthesized by a one-step co-reduction of aqueous solution of ruthenium (III) chloride, cupric (II) chloride, and graphite oxide (GO) with ammonia borane (AB) under ambient condition. The nature of the NPs was fully characterized by TEM, HRTEM, XRD, energy dispersive spectroscopy (EDX), and X-ray photoelectron spectroscopy (XPS). The as-synthesized NPs exhibit much higher catalytic activity for hydrolytic dehydrogenation of AB than the monometallic Ru and Cu, bimetallic RuCu/graphene reduced by NaBH{sub 4}, and graphene free RuCu counterparts. Additionally, the as-synthesized NPs supported on graphene exhibit higher catalytic activity than the catalysts with other conventional supports, such as SiO{sub 2}, γ-Al{sub 2}O{sub 3}, and carbon black. The activity of Ru{sub 1}Cu{sub 7.5}/graphene NPs in terms of turnover frequency (TOF) is 135 mol H{sub 2} min{sup −1} (mol Ru){sup −1}, which is higher than Ru/graphene, and most reported Ru-based or other noble metal-based NPs for the catalytic hydrolysis of AB. The activation energy for hydrolysis of AB in the presence of Ru{sub 1}Cu{sub 7.5}/graphene NPs was determined as 30.59 kJ mol{sup −1}, which is lower than most of the reported catalysts. Furthermore, the as-prepared NPs exert satisfied durable stability for the hydrolytic dehydrogenation of AB.

  14. Reducing ammonia emissions in Europe

    DEFF Research Database (Denmark)

    Jacobsen, Brian H.

    2011-01-01

    The NEC directive has set targets for the 2010 ammonia emissions from a number of European countries. The target will be reached by most EU-countries and the total emission for EU-27 has been reduced by 22% from 1990 to 2007. Denmark is one of the countries with the largest reductions since 1990...... to the high expectations at the outset. Despite this, the paper concludes that Denmark is likely to reduce emission by 50% from 1990 to 2020 and reach the likely 2020 NEC ceiling....

  15. Catalytic ignition of light hydrocarbons

    Institute of Scientific and Technical Information of China (English)

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

    2009-01-01

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

  16. Dihydrogen Phosphate Stabilized Ruthenium(0 Nanoparticles: Efficient Nanocatalyst for The Hydrolysis of Ammonia-Borane at Room Temperature

    Directory of Open Access Journals (Sweden)

    Feyyaz Durap

    2015-07-01

    Full Text Available Intensive efforts have been devoted to the development of new materials for safe and efficient hydrogen storage. Among them, ammonia-borane appears to be a promising candidate due to its high gravimetric hydrogen storage capacity. Ammonia-borane can release hydrogen on hydrolysis in aqueous solution under mild conditions in the presence of a suitable catalyst. Herein, we report the synthesis of ruthenium(0 nanoparticles stabilized by dihydrogenphosphate anions with an average particle size of 2.9 ± 0.9 nm acting as a water-dispersible nanocatalyst in the hydrolysis of ammonia-borane. They provide an initial turnover frequency (TOF value of 80 min−1 in hydrogen generation from the hydrolysis of ammonia-borane at room temperature. Moreover, the high stability of these ruthenium(0 nanoparticles makes them long-lived and reusable nanocatalysts for the hydrolysis of ammonia-borane. They provide 56,800 total turnovers and retain ~80% of their initial activity even at the fifth catalytic run in the hydrolysis of ammonia-borane at room temperature.

  17. Ammonia Synthesis using Ti and Nb Nitride Nano-particles Prepared by Mesoporous Graphitic C3N4

    KAUST Repository

    Kumagai, Hiromu

    2015-01-22

    TiN and NbN nanoparticles were synthesized from mesoporous graphitic C3N4 (mpg-C3N4) as a reactive template and used as the catalyst for ammonia synthesis. The obtained TiN and NbN nanoparticles possess high surface areas of 299 and 275 m2 g-1, respectively, making them attractive in the use of catalysis and support. Although most of the TiN and NbN particles show no measurable activity for ammonia formation, the nanoparticles enabled an ammonia synthesis rate of 31 μmol h-1 g-cat-1 at 673 K and 0.1 MPa of synthesis gas (N2 + 3H2) for both TiN and NbN catalysts. It is evident that the formation of nanoparticles with high nitride surface area is essential for the materials to function as catalysts in ammonia synthesis. The addition of Fe to TiN enhanced the ammonia synthesis activity, whereas it had detrimental effects on the catalytic activity of NbN. The properties of these catalysts in ammonia synthesis are discussed.

  18. Atmospheric behaviour of ammonia and ammonium.

    NARCIS (Netherlands)

    Asman, W.A.J.

    1987-01-01

    1.4.1 Scope of this thesisA few models for ammonia and ammonium exist. Russell et al. (1983) made a multi-layer Lagrangian transport model describing the transport and formation of ammonium nitrate aerosol for California. They did not take reactions of ammonia and sulphuric acid into account, nor we

  19. Nitrocarburizing in ammonia-hydrocarbon gas mixtures

    DEFF Research Database (Denmark)

    Pedersen, Hanne; Christiansen, Thomas; Somers, Marcel A. J.

    2011-01-01

    The present work investigates the possibility of nitrocarburising in ammonia-acetylene-hydrogen and ammonia-propene-hydrogen gas mixtures, where unsaturated hydrocarbon gas is the carbon source during nitrocarburising. Consequently, nitrocarburising is carried out in a reducing atmosphere and str...

  20. Regeneration of ammonia borane from polyborazylene

    Science.gov (United States)

    Sutton, Andrew; Gordon, John C; Ott, Kevin C; Burrell, Anthony K

    2013-02-05

    Method of producing ammonia borane, comprising providing a reagent comprising a dehydrogenated material in a suitable solvent; and combining the reagent with a reducing agent comprising hydrazine, a hydrazine derivative, or combinations thereof, in a reaction which produces a mixture comprising ammonia borane.

  1. Method for releasing hydrogen from ammonia borane

    Science.gov (United States)

    Varma, Arvind; Diwan, Moiz; Shafirovich, Evgeny; Hwang, Hyun-Tae; Al-Kukhun, Ahmad

    2013-02-19

    A method of releasing hydrogen from ammonia borane is disclosed. The method comprises heating an aqueous ammonia borane solution to between about 80-135.degree. C. at between about 14.7 and 200 pounds per square inch absolute (psia) to release hydrogen by hydrothermolysis.

  2. Ammonia and hydrogen sulfide removal using biochar

    Science.gov (United States)

    Reducing ammonia and hydrogen sulfide emissions from livestock facilities is an important issue for many communities and livestock producers. Ammonia has been regarded as odorous, precursor for particulate matter (PM), and contributed to livestock mortality. Hydrogen sulfide is highly toxic at elev...

  3. Ammonia Solubility in High Concentration Salt Solutions

    International Nuclear Information System (INIS)

    Solubility data for ammonia in water and various dilute solutions are abundant in the literature. However, there is a noticeable lack of ammonia solubility data for high salt, basic solutions of various mixtures of salts including those found in many of the Hanford Washington underground waste tanks. As a result, models based on solubility data for dilute salt solutions have been used to extrapolate to high salt solutions. These significant extrapolations need to be checked against actual laboratory data. Some indirect vapor measurements have been made. A more direct approach is to determine the ratio of solubility of ammonia in water to its solubility in high salt solutions. In various experiments, pairs of solutions, one of which is water and the other a high salt solution, are allowed to come to equilibrium with a common ammonia vapor pressure. The ratio of concentrations of ammonia in the two solutions is equal to the ratio of the respective ammonia solubilities (Henry's Law constants) at a given temperature. This information can then be used to refine the models that predict vapor space compositions of ammonia. Ammonia at Hanford is of concern because of its toxicity in the environment and its contribution to the flammability of vapor space gas mixtures in waste tanks

  4. Ammonia Sensor Using Wavelength Modulation Spectroscopy

    KAUST Repository

    Farooq, Aamir

    2015-09-01

    An ammonia sensor can include a laser detector configured to provide stable sample readings. The sensor can implement a method including processing the recorded intensity of the laser beam to determine a first harmonic component and a second harmonic component and the amount of ammonia in the sample.

  5. Catalytic fast pyrolysis of lignocellulosic biomass

    Energy Technology Data Exchange (ETDEWEB)

    Liu, Changjun; Wang, Huamin; Karim, Ayman M.; Sun, Junming; Wang, Yong

    2014-11-21

    Increasing energy demand, especially in the transportation sector, and soaring CO2 emissions necessitate the exploitation of renewable sources of energy. Despite the large variety of new energy Q3 carriers, liquid hydrocarbon still appears to be the most attractive and feasible form of transportation fuel taking into account the energy density, stability and existing infrastructure. Biomass is an abundant, renewable source of energy; however, utilizing it in a cost-effective way is still a substantial challenge. Lignocellulose is composed of three major biopolymers, namely cellulose, hemicellulose and lignin. Fast pyrolysis of biomass is recognized as an efficient and feasible process to selectively convert lignocellulose into a liquid fuel—bio-oil. However bio-oil from fast pyrolysis contains a large amount of oxygen, distributed in hundreds of oxygenates. These oxygenates are the cause of many negative properties, such as low heating values, high corrosiveness, high viscosity, and instability; they also greatly Q4 limit the application of bio-oil particularly as transportation fuel. Hydrocarbons derived from biomass are most attractive because of their high energy density and compatibility with the existing infrastructure. Thus, converting lignocellulose into transportation fuels via catalytic fast pyrolysis has attracted much attention. Many studies related to catalytic fast pyrolysis of biomass have been published. The main challenge of this process is the development of active and stable catalysts that can deal with a large variety of decomposition intermediates from lignocellulose. This review starts with the current understanding of the chemistry in fast pyrolysis of lignocellulose and focuses on the development of catalysts in catalytic fast pyrolysis. Recent progress in the experimental studies on catalytic fast pyrolysis of biomass is also summarized with the emphasis on bio-oil yields and quality.

  6. A high-density ammonia storage/delivery system based on Mg(NH3)6Cl2 for SCR-DeNOx in vehicles

    DEFF Research Database (Denmark)

    Elmøe, Tobias Dokkedal; Sørensen, Rasmus Zink; Quaade, Ulrich;

    2006-01-01

    In this paper, we present a new benchmark for the automobile selective catalytic reduction of NO(x): Mg(NH(3))(6)Cl(2). This solid complex releases ammonia upon heating and can be compacted into a dense shape which is both easy to handle and safe. Furthermore, the material has a high volumetric a...

  7. Catalytic coherence transformations

    Science.gov (United States)

    Bu, Kaifeng; Singh, Uttam; Wu, Junde

    2016-04-01

    Catalytic coherence transformations allow the otherwise impossible state transformations using only incoherent operations with the aid of an auxiliary system with finite coherence that is not being consumed in any way. Here we find the necessary and sufficient conditions for the deterministic and stochastic catalytic coherence transformations between a pair of pure quantum states. In particular, we show that the simultaneous decrease of a family of Rényi entropies of the diagonal parts of the states under consideration is a necessary and sufficient condition for the deterministic catalytic coherence transformations. Similarly, for stochastic catalytic coherence transformations we find the necessary and sufficient conditions for achieving a higher optimal probability of conversion. We thus completely characterize the coherence transformations among pure quantum states under incoherent operations. We give numerous examples to elaborate our results. We also explore the possibility of the same system acting as a catalyst for itself and find that indeed self-catalysis is possible. Further, for the cases where no catalytic coherence transformation is possible we provide entanglement-assisted coherence transformations and find the necessary and sufficient conditions for such transformations.

  8. Decomposition methods for unsupervised learning

    DEFF Research Database (Denmark)

    Mørup, Morten

    2008-01-01

    to their generalizations to multi-way array, i.e. tensor decomposition, through models such as the CanDecomp/ PARAFAC and the Tucker model. Extensions for these types of decomposition models to incorporate shift, reverberation and general transformations are also described. Finally, a connection between decomposition...... methods and clustering problems is derived both in terms of classical point clustering but also in terms of community detection in complex networks. A guiding principle throughout this thesis is the principle of parsimony. Hence, the goal of Unsupervised Learning is here posed as striving for simplicity...... to the analysis of social network data....

  9. AUTONOMOUS GAUSSIAN DECOMPOSITION

    Energy Technology Data Exchange (ETDEWEB)

    Lindner, Robert R.; Vera-Ciro, Carlos; Murray, Claire E.; Stanimirović, Snežana; Babler, Brian [Department of Astronomy, University of Wisconsin, 475 North Charter Street, Madison, WI 53706 (United States); Heiles, Carl [Radio Astronomy Lab, UC Berkeley, 601 Campbell Hall, Berkeley, CA 94720 (United States); Hennebelle, Patrick [Laboratoire AIM, Paris-Saclay, CEA/IRFU/SAp-CNRS-Université Paris Diderot, F-91191 Gif-sur Yvette Cedex (France); Goss, W. M. [National Radio Astronomy Observatory, P.O. Box O, 1003 Lopezville, Socorro, NM 87801 (United States); Dickey, John, E-mail: rlindner@astro.wisc.edu [University of Tasmania, School of Maths and Physics, Private Bag 37, Hobart, TAS 7001 (Australia)

    2015-04-15

    We present a new algorithm, named Autonomous Gaussian Decomposition (AGD), for automatically decomposing spectra into Gaussian components. AGD uses derivative spectroscopy and machine learning to provide optimized guesses for the number of Gaussian components in the data, and also their locations, widths, and amplitudes. We test AGD and find that it produces results comparable to human-derived solutions on 21 cm absorption spectra from the 21 cm SPectral line Observations of Neutral Gas with the EVLA (21-SPONGE) survey. We use AGD with Monte Carlo methods to derive the H i line completeness as a function of peak optical depth and velocity width for the 21-SPONGE data, and also show that the results of AGD are stable against varying observational noise intensity. The autonomy and computational efficiency of the method over traditional manual Gaussian fits allow for truly unbiased comparisons between observations and simulations, and for the ability to scale up and interpret the very large data volumes from the upcoming Square Kilometer Array and pathfinder telescopes.

  10. Clinical utility of breath ammonia for evaluation of ammonia physiology in healthy and cirrhotic adults.

    Science.gov (United States)

    Spacek, Lisa A; Mudalel, Matthew; Tittel, Frank; Risby, Terence H; Solga, Steven F

    2015-12-01

    Blood ammonia is routinely used in clinical settings to assess systemic ammonia in hepatic encephalopathy and urea cycle disorders. Despite its drawbacks, blood measurement is often used as a comparator in breath studies because it is a standard clinical test. We sought to evaluate sources of measurement error and potential clinical utility of breath ammonia compared to blood ammonia. We measured breath ammonia in real time by quartz enhanced photoacoustic spectrometry and blood ammonia in 10 healthy and 10 cirrhotic participants. Each participant contributed 5 breath samples and blood for ammonia measurement within 1 h. We calculated the coefficient of variation (CV) for 5 breath ammonia values, reported medians of healthy and cirrhotic participants, and used scatterplots to display breath and blood ammonia. For healthy participants, mean age was 22 years (±4), 70% were men, and body mass index (BMI) was 27 (±5). For cirrhotic participants, mean age was 61 years (±8), 60% were men, and BMI was 31 (±7). Median blood ammonia for healthy participants was within normal range, 10 μmol L(-1) (interquartile range (IQR), 3-18) versus 46 μmol L(-1) (IQR, 23-66) for cirrhotic participants. Median breath ammonia was 379 pmol mL(-1) CO2 (IQR, 265-765) for healthy versus 350 pmol mL(-1) CO2 (IQR, 180-1013) for cirrhotic participants. CV was 17  ±  6%. There remains an important unmet need in the evaluation of systemic ammonia, and breath measurement continues to demonstrate promise to fulfill this need. Given the many differences between breath and blood ammonia measurement, we examined biological explanations for our findings in healthy and cirrhotic participants. We conclude that based upon these preliminary data breath may offer clinically important information this is not provided by blood ammonia.

  11. Enhancing Biogas Production from Anaerobically Digested Wheat Straw Through Ammonia Pretreatment

    Institute of Scientific and Technical Information of China (English)

    杨懂艳; 庞云芝; 袁海荣; 陈树林; 马晶伟; 郁亮; 李秀金

    2014-01-01

    Aqueous ammonia was used to pretreat wheat straw to improve biodegradability and provide nitrogen source for enhancing biogas production. Three doses of ammonia (2%, 4%, and 6%, dry matter) and three moisture contents (30%, 60%, and 80%, dry matter) were applied to pretreat wheat straw for 7 days. The pretreated wheat straws were anaerobically digested at three loading rates (50, 65, and 80 g·L-1) to produce biogas. The results indi-cated that the wheat straw pretreated with 80%moisture content and 4%ammonia achieved the highest methane yield of 199.7 ml·g-1 (based on per unit volatile solids loaded), with shorter digestion time (T80) of 25 days at the loading rate of 65 g·L-1 compared to untreated one. The main chemical compositions of wheat straw were also ana-lyzed. The cellulose and hemicellulose contents were decomposed by 2%-20%and 26%-42%, respectively, while the lignin content was hardly removed, cold-water and hot-water extracts were increased by 4%-44%, and 12%-52%, respectively, for the ammonia-pretreated wheat straws at different moisture contents. The appropriate C/N ratio and decomposition of original chemical compositions into relatively readily biodegradable substances will improve the biodegradability and biogas yield.

  12. Gas Turbine Combustion and Ammonia Removal Technology of Gasified Fuels

    Directory of Open Access Journals (Sweden)

    Takeharu Hasegawa

    2010-03-01

    Full Text Available From the viewpoints of securing a stable supply of energy and protecting our global environment in the future, the integrated gasification combined cycle (IGCC power generation of various gasifying methods has been introduced in the world. Gasified fuels are chiefly characterized by the gasifying agents and the synthetic gas cleanup methods and can be divided into four types. The calorific value of the gasified fuel varies according to the gasifying agents and feedstocks of various resources, and ammonia originating from nitrogenous compounds in the feedstocks depends on the synthetic gas clean-up methods. In particular, air-blown gasified fuels provide low calorific fuel of 4 MJ/m3 and it is necessary to stabilize combustion. In contrast, the flame temperature of oxygen-blown gasified fuel of medium calorie between approximately 9–13 MJ/m3 is much higher, so control of thermal-NOx emissions is necessary. Moreover, to improve the thermal efficiency of IGCC, hot/dry type synthetic gas clean-up is needed. However, ammonia in the fuel is not removed and is supplied into the gas turbine where fuel-NOx is formed in the combustor. For these reasons, suitable combustion technology for each gasified fuel is important. This paper outlines combustion technologies and combustor designs of the high temperature gas turbine for various IGCCs. Additionally, this paper confirms that further decreases in fuel-NOx emissions can be achieved by removing ammonia from gasified fuels through the application of selective, non-catalytic denitration. From these basic considerations, the performance of specifically designed combustors for each IGCC proved the proposed methods to be sufficiently effective. The combustors were able to achieve strong results, decreasing thermal-NOx emissions to 10 ppm (corrected at 16% oxygen or less, and fuel-NOx emissions by 60% or more, under conditions where ammonia concentration per fuel heating value in unit volume was 2.4 × 102 ppm

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

    NARCIS (Netherlands)

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

    2013-01-01

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

  14. Some nonlinear space decomposition algorithms

    Energy Technology Data Exchange (ETDEWEB)

    Tai, Xue-Cheng; Espedal, M. [Univ. of Bergen (Norway)

    1996-12-31

    Convergence of a space decomposition method is proved for a general convex programming problem. The space decomposition refers to methods that decompose a space into sums of subspaces, which could be a domain decomposition or a multigrid method for partial differential equations. Two algorithms are proposed. Both can be used for linear as well as nonlinear elliptic problems and they reduce to the standard additive and multiplicative Schwarz methods for linear elliptic problems. Two {open_quotes}hybrid{close_quotes} algorithms are also presented. They converge faster than the additive one and have better parallelism than the multiplicative method. Numerical tests with a two level domain decomposition for linear, nonlinear and interface elliptic problems are presented for the proposed algorithms.

  15. Expression, crystallization and preliminary X-ray crystallographic study of ethanolamine ammonia-lyase from Escherichia coli

    International Nuclear Information System (INIS)

    Ethanolamine ammonia-lyase from E. coli has been overexpressed, purified and crystallized. The crystals diffracted to 2.2 Å resolution using synchrotron radiation. Ethanolamine ammonia-lyase (EAL) catalyzes the adenosylcobalamin-dependent conversion of ethanolamine to acetaldehyde and ammonia. The wild-type enzyme shows a very low solubility. N-terminal truncation of the Escherichia coli EAL β-subunit dramatically increases the solubility of the enzyme without altering its catalytic properties. Two deletion mutants of the enzyme [EAL(βΔ4–30) and EAL(βΔ4–43)] have been overexpressed, purified and crystallized using the sitting-drop vapour-diffusion method. Crystals of EAL(βΔ4–30) and EAL(βΔ4–43) diffracted to approximately 8.0 and 2.1 Å resolution, respectively

  16. Ambient pressure proton transfer mass spectrometry: detection of amines and ammonia.

    Science.gov (United States)

    Hanson, D R; McMurry, P H; Jiang, J; Tanner, D; Huey, L G

    2011-10-15

    An instrument to detect gaseous amines and ammonia is described, and representative data from an urban site and a laboratory setting are presented. The instrument, an Ambient pressure Proton transfer Mass Spectrometer (AmPMS), consists of a chemical ionization and drift region at atmospheric pressure coupled to a standard quadrupole mass spectrometer. Calibrations show that AmPMS sensitivity is good for amines, and AmPMS backgrounds were suitably determined by diverting sampled air through a catalytic converter. In urban air at a site in Atlanta, amines were detected at subpptv levels for methyl and dimethyl amine which were generally at a low abundance of ammonia were high, and data are very limited for these species. Improvements in detecting amines and ammonia from a smog chamber were evident due to improvements in AmPMS background determination; notably dimethyl amine and its OH oxidation products were followed along with impurity ammonia and other species. Future work will focus on accurate calibration standards and on improving the sample gas inlet.

  17. CFD modelling of flow mal-distribution in an industrial ammonia oxidation reactor: A case study

    International Nuclear Information System (INIS)

    Ammonia oxidation reactor is widely used in nitric acid plant to cause the catalytic reaction between air and ammonia to produce nitrous gases. In this work, the flow distribution inside the ammonia oxidation reactor at Shiraz Petrochemical Complex (SPC) has been simulated using Computational Fluid Dynamics (CFD) code. The CFD results showed that the flow is non-uniformly distributed inside the reactor due to improper header design of the reactor. Measuring of the temperature distribution around the skin of the reactor has been carried out using thermograph. The thermograph experiment showed a considerable temperature difference between the left and right side of the reactor. It was found that the mal-distribution of the gas flow inside the reactor can directly affect the performance of the reactor. - Highlights: •A failure has been observed in an industrial ammonia oxidation reactor. •CFD code helps to simulate the flow inside the reactor. •The flow becomes non-uniformly distributed due to the reactor header mal-design. •The flow mal-distribution results in some drawbacks

  18. Gaseous ammonia in the urban area of Rome, Italy and its relationship with traffic emissions

    Science.gov (United States)

    Perrino, C.; Catrambone, M.; Di Menno Di Bucchianico, A.; Allegrini, I.

    The atmospheric concentration of gaseous ammonia has been measured during selected field campaigns from the spring of 2001 to the spring of 2002 in the urban area of Rome, at many traffic sites and at an urban background site. The concentration level at the traffic sites was in all cases about five times the background level and always much higher than the concentration in a rural near-city area. The time trend of ammonia is well correlated with the trend of a primary low-reactivity pollutant such as carbon monoxide. The concentration values of both pollutants depend on the intensity of traffic emission and on the atmospheric mixing in the boundary layer. Ammonia concentration is also dependent on the air temperature. A close link between NH 3 and CO air values has been confirmed at all the measurement stations of the Air Quality Network of Rome. These results indicate that the emissions from petrol-engine vehicles equipped with catalytic converters can be an important source of ammonia in urban areas. The implications of these findings for the chemistry of the urban atmosphere need to be carefully considered.

  19. Decomposition Approaches for Optimization Problems

    OpenAIRE

    Kinable, Joris

    2014-01-01

    This dissertation encompasses the development of decomposition approaches for a variety of both real-world and fundamental optimization problems. Many optimization problems comprise of multiple interconnected subproblems, often rendering them too large or too complicated to solve as a single integral problem. Decomposition approaches are required to deal with these problems efficiently. By decomposing a problem into multiple subproblems, efficient dedicated procedures can be employed to solve...

  20. Orthogonal decomposition of Lorentz transformations

    OpenAIRE

    Hanson, Jason

    2011-01-01

    The canonical decomposition of a Lorentz algebra element into a sum of orthogonal simple (decomposable) Lorentz bivectors is discussed, as well as the decomposition of a proper orthochronous Lorentz transformation into a product of commuting Lorentz transformations, each of which is the exponential of a simple bivector. As an application, we obtain an alternative method of deriving the formulas for the exponential and logarithm for Lorentz transformations.

  1. Additive decompositions with interaction effects

    OpenAIRE

    Biewen, Martin

    2012-01-01

    This paper proposes a comprehensive, path-independent decomposition formula of changes into ceteris paribus effects and interaction effects. The formula implies a reassessment of sequential decomposition methods that are widely used in the literature and that are restrictive in how they treat interaction effects. If counterfactual outcomes are correctly specified, it may also be viewed as a description of certain aspects of causality in the situation where more than one causal influence is pr...

  2. TREE DECOMPOSITIONS OF MULTIGRAPHS

    Institute of Scientific and Technical Information of China (English)

    SHI Minyong

    1999-01-01

    For a graph G, ifE(G) can be partitioned into several pairwise disjointsets as { E1, E2,……,El} such thatthe subgraph induced by Ei is a tree of orderki, (i=1,2, ……, l), then G is said to have a {k1,k2,……, kl}-tree-decomposition, denoted by {k1,k2,……, kl}∈G.For k≥1 and l≥0, a collection(G)(k,l) is the setof multigraphs such that G∈(G)(k,l) if and only if ε(G) = k(|G|-1)-l and ε(H)≤max{(k-1)(|H|-1), k(|H|-1)-l} for any subgraph H of G.We prove that (1) If k≥2, 0≤l≤3 and G∈(G)(k,l) of order n≥l+1, then {n,n,……, n-l}∈ G. (2) If k≥2 and G∈(G)(k,2) oforder n≥3, then {n,n,……, n,n-2}∈G and {n,n,……, n,n-1,n-1}∈G. (3) If k3 and G∈(G)(k,3) oforder n≥4, then {n,n,……, n,n-3}∈G ,{ n,n,……, n,n-1,n-2}∈ G and {n,n, ……, n,n-1,n-1,n-1}∈G.

  3. Influence of alumina binder content on catalytic performance of Ni/HZSM-5 for hydrodeoxygenation of cyclohexanone.

    Science.gov (United States)

    Kong, Xiangjin; Liu, Junhai

    2014-01-01

    The influence of the amount of alumina binders on the catalytic performance of Ni/HZSM-5 for hydrodeoxygenation of cyclohexanone was investigated in a fixed-bed reactor. N2 sorption, X-ray diffraction, H2-chemisorption and temperature-programmed desorption of ammonia were used to characterize the catalysts. It can be observed that the Ni/HZSM-5 catalyst bound with 30 wt.% alumina binder exhibited the best catalytic performance. The high catalytic performance may be due to relatively good Ni metal dispersion, moderate mesoporosity, and proper acidity of the catalyst.

  4. Influence of alumina binder content on catalytic performance of Ni/HZSM-5 for hydrodeoxygenation of cyclohexanone.

    Directory of Open Access Journals (Sweden)

    Xiangjin Kong

    Full Text Available The influence of the amount of alumina binders on the catalytic performance of Ni/HZSM-5 for hydrodeoxygenation of cyclohexanone was investigated in a fixed-bed reactor. N2 sorption, X-ray diffraction, H2-chemisorption and temperature-programmed desorption of ammonia were used to characterize the catalysts. It can be observed that the Ni/HZSM-5 catalyst bound with 30 wt.% alumina binder exhibited the best catalytic performance. The high catalytic performance may be due to relatively good Ni metal dispersion, moderate mesoporosity, and proper acidity of the catalyst.

  5. Preparation of mesoporous activated carbons from coal liquefaction residue for methane decomposition

    Institute of Scientific and Technical Information of China (English)

    Jianbo Zhang; Lijun Jin; Shengwei Zhu; Haoquan Hu

    2012-01-01

    Mesoporous activated carbons were prepared from direct coal liquefaction residue (CLR) by KOH activation method,and the experiments were carried out to investigate the effects of KOH/CLR ratio,solvent for mixing the CLR and KOH,and carbonization procedure on the resultant carbon texture and catalytic activity for catalytic methane decomposition (CMD).The results showed that optimal KOH/CLR ratio of 2 ∶ 1;solvent with higher solubility to KOH or the CLR,and an appropriate carbonization procedure are conductive to improving the carbon pore structure and catalytic activity for CMD.The resultant mesoporous carbons show higher and more stable activity than microporous carbons.Additionally,the relationship between the carbon textural properties and the catalytic activity for CMD was also discussed.

  6. Moduli via double pants decompositions

    CERN Document Server

    Felikson, Anna

    2011-01-01

    We consider (local) parametrizations of Teichmuller space $T_{g,n}$ (of genus $g$ hyperbolic surfaces with $n$ boundary components) by lengths of $6g-6+3n$ geodesics. We find a large family of suitable sets of $6g-6+3n$ geodesics, each set forming a special structure called "admissible double pants decomposition". For admissible double pants decompositions containing no double curves we show that the lengths of curves contained in the decomposition determine the point of $T_{g,n}$ up to finitely many choices. Moreover, these lengths provide a local coordinate in a neighborhood of all points of $T_{g,n}\\setminus X$, where $X$ is a union of $3g-3+n$ hypersurfaces. Furthermore, there exists a groupoid acting transitively on admissible double pants decompositions and generated by transformations exchanging only one curve of the decomposition. The local charts arising from different double pants decompositions compose an atlas covering the Teichmuller space. The gluings of the adjacent charts are coming from the e...

  7. Low-cost anodes for ammonia electrooxidation

    Science.gov (United States)

    Selverston, Steven M.

    This research focused on the development of low-cost electrodes for the electrochemical oxidation of ammonia to nitrogen, a reaction that has possible applications in hydrogen generation, direct ammonia fuel cells, water treatment, and sensors. Statistical design of experiments was used to help develop an efficient and scalable process for electrodeposition of platinum with a specific electrochemical surface area of over 25 m2 /g. Catalyst surface area and activity were evaluated using cyclic voltammetry, and the material microstructure and morphology were investigated using x-ray diffraction and scanning electron microscopy. The synthesized electrodes were found to be active toward the ammonia electrooxidation reaction, particularly when supporting electrolyte was added. However, supporting electrolyte was not required in order to oxidize the ammonia. As proof of concept, a homemade direct ammonia fuel cell employing a commercial anion exchange membrane was tested at room temperature with gravity-fed fuel and without supporting electrolyte. At room temperature, with passive reactant supply and using dissolved oxygen at the cathode, the cell produced about one quarter the power of a direct methanol fuel cell that used active transport of humidified oxygen and preheated (50 °C) methanol. With continued development of the membrane, cathode and membrane electrode assembly, the passive direct ammonia fuel cell using anion exchange membrane could have performance similar to the equivalent direct methanol fuel cell, and it could benefit from many advantages of ammonia over methanol such as lower cost, higher energy density, and reduced greenhouse gas emissions.

  8. WOOD COLOR CHANGES BY AMMONIA FUMING

    Directory of Open Access Journals (Sweden)

    Josip Miklečić,

    2012-06-01

    Full Text Available This paper studies the influence of ammonia gas on wood color changes in response to an increasing demand for dark colored wood specimens. The darker wood color in ammonia fuming is accomplished through chemical reactions between ammonia gas and wood compounds. We exposed oak, maple, spruce, and larch wood samples to ammonia gas for 16 days. During fuming, the color changes were studied using CIE L*a*b* parameters. After fuming, the changes in extractives content, tannin, and nitrogen content were analyzed. The chemical changes of wood and residues of wood extractives after fuming were analyzed by FTIR spectroscopy. Oak wood reacted intensively with ammonia gas in a very short time, and the darkening was prominent for all the investigated wood species. It was established that tannin had no major influence on color changes of maple and larch wood in the ammonia-fuming process. The FTIR spectra of fumed wood indicated involvement of carbonyl groups, and the FTIR spectra of wood extractives indicated involvement of carbonyl, aromatic, and alcohol groups in reaction with ammonia gas.

  9. Resveratrol prevents ammonia toxicity in astroglial cells.

    Directory of Open Access Journals (Sweden)

    Larissa Daniele Bobermin

    Full Text Available Ammonia is implicated as a neurotoxin in brain metabolic disorders associated with hyperammonemia. Acute ammonia toxicity can be mediated by an excitotoxic mechanism, oxidative stress and nitric oxide (NO production. Astrocytes interact with neurons, providing metabolic support and protecting against oxidative stress and excitotoxicity. Astrocytes also convert excess ammonia and glutamate into glutamine via glutamine synthetase (GS. Resveratrol, a polyphenol found in grapes and red wines, exhibits antioxidant and anti-inflammatory properties and modulates glial functions, such as glutamate metabolism. We investigated the effect of resveratrol on the production of reactive oxygen species (ROS, GS activity, S100B secretion, TNF-α, IL-1β and IL-6 levels in astroglial cells exposed to ammonia. Ammonia induced oxidative stress, decreased GS activity and increased cytokines release, probably by a mechanism dependent on protein kinase A (PKA and extracellular signal-regulated kinase (ERK pathways. Resveratrol prevented ammonia toxicity by modulating oxidative stress, glial and inflammatory responses. The ERK and nuclear factor-κB (NF-κB are involved in the protective effect of resveratrol on cytokines proinflammatory release. In contrast, other antioxidants (e.g., ascorbic acid and trolox were not effective against hyperammonemia. Thus, resveratrol could be used to protect against ammonia-induced neurotoxicity.

  10. Ammonia synthesis using magnetic induction method (MIM)

    Science.gov (United States)

    Puspitasari, P.; Razak, J. Abd; Yahya, N.

    2012-09-01

    The most challenging issues for ammonia synthesis is to get the high yield. New approach of ammonia synthesis by using Magnetic Induction Method (MIM) and the Helmholtz Coils has been proposed. The ammonia detection was done by using Kjeldahl Method and FTIR. The system was designed by using Autocad software. The magnetic field of MIM was vary from 100mT-200mT and the magnetic field for the Helmholtz coils was 14mT. The FTIR result shows that ammonia has been successfully formed at stretching peaks 1097,1119,1162,1236, 1377, and 1464 cm-1. UV-VIS result shows the ammonia bond at 195nm of wavelength. The ammonia yield was increase to 244.72μmole/g.h by using the MIM and six pairs of Helmholtz coils. Therefore this new method will be a new promising method to achieve the high yield ammonia at ambient condition (at 25δC and 1atm), under the Magnetic Induction Method (MIM).

  11. Amônia (NH3 atmosférica: fontes, transformação, sorvedouros e métodos de análise Atmospheric ammonia: sources, transformation, sinks, and methods of analysis

    Directory of Open Access Journals (Sweden)

    Erika Pereira Felix

    2004-02-01

    Full Text Available Ammonia is the most common alkaline gas of the atmosphere, being important in the neutralization of various processes that occur in the atmosphere. Its main sources of emission are the decomposition of organic matter and dejections of animals. Ammonia is used by man in diverse activities of production, therefore it is a gas that can contaminate work environments. Measurements of ammonia concentration in some parts of the world have shown great spatial and weather variation. This large variability makes it difficult to estimate the input of reduced nitrogen to different ecosystems from measurements.

  12. Catalytic Conversion of Biofuels

    DEFF Research Database (Denmark)

    Jørgensen, Betina

    This thesis describes the catalytic conversion of bioethanol into higher value chemicals. The motivation has been the unavoidable coming depletion of the fossil resources. The thesis is focused on two ways of utilising ethanol; the steam reforming of ethanol to form hydrogen and the partial oxida...

  13. Catalytic Phosphination and Arsination

    Institute of Scientific and Technical Information of China (English)

    Kwong Fuk Yee; Chan Kin Shing

    2004-01-01

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

  14. Catalytic efficiency of designed catalytic proteins.

    Science.gov (United States)

    Korendovych, Ivan V; DeGrado, William F

    2014-08-01

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

  15. Kinetic modeling of Pt catalyzed and computation-driven catalyst discovery for ethylene glycol decomposition

    Energy Technology Data Exchange (ETDEWEB)

    Salciccioli, M.; Vlachos, D. G.

    2011-10-07

    Knowledge of the underlying mechanisms controlling oxygenate catalytic decomposition to synthesis gas can lead to the design of better catalysts and reactors, enabling the utilization of biomass feedstock for fuels and chemicals. This work studies the decomposition of ethylene glycol, as a simple surrogate to biomass-derived polyols, through the analysis of two catalytic kinetic models. First, a density functional theory (DFT) and statistical mechanical parametrized model of 81 reversible, elementary-like reactions is used to predict and understand ethylene glycol decomposition on Pt. Reaction path analysis indicates that while the majority of decomposition occurs through initial O–H bond breaking, initial C–H bond breaking is active at temperatures around 500 K. Further, sensitivity analysis shows that early dehydrogenation reactions (specifically HOCH₂CH₂O* → HOCH₂CHO* + H*) are kinetically important reactions, rather than C–C bond breaking. We show that steady state reactor conditions open up new reaction pathways not seen in surface science (temperature programmed desorption) experiments. The second model, parametrized based on semiempirical linear scaling and linear free energy relationships, consists of 250 reversible, elementary-like reactions and maps the dependence of ethylene glycol decomposition rate and selectivity to various products versus atomic binding energy descriptors. The results show that an optimal catalyst that maximizes the H₂ production rate should have binding energies of 58, 116, and 145 kcal/mol for atomic hydrogen, oxygen, and carbon, respectively. These models can be used to guide future experimental efforts in developing catalysts for polyol reforming.

  16. Poisoning of bubble propelled catalytic micromotors: the chemical environment matters

    Science.gov (United States)

    Zhao, Guanjia; Sanchez, Samuel; Schmidt, Oliver G.; Pumera, Martin

    2013-03-01

    Self-propelled catalytic microjets have attracted considerable attention in recent years and these devices have exhibited the ability to move in complex media. The mechanism of propulsion is via the Pt catalysed decomposition of H2O2 and it is understood that the Pt surface is highly susceptible to poisoning by sulphur-containing molecules. Here, we show that important extracellular thiols as well as basic organic molecules can significantly hamper the motion of catalytic microjet engines. This is due to two different mechanisms: (i) molecules such as dimethyl sulfoxide can quench the hydroxyl radicals produced at Pt surfaces and reduce the amount of oxygen gas generated and (ii) molecules containing -SH, -SSR, and -SCH3 moieties can poison the catalytically active platinum surface, inhibiting the motion of the jet engines. It is essential that the presence of such molecules in the environment be taken into consideration for future design and operation of catalytic microjet engines. We show this effect on catalytic micromotors prepared by both rolled-up and electrodeposition approaches, demonstrating that such poisoning is universal for Pt catalyzed micromotors. We believe that our findings will contribute significantly to this field to develop alternative systems or catalysts for self-propulsion when practical applications in the real environment are considered.

  17. Real interest parity decomposition

    Directory of Open Access Journals (Sweden)

    Alex Luiz Ferreira

    2009-09-01

    Full Text Available The aim of this paper is to investigate the general causes of real interest rate differentials (rids for a sample of emerging markets for the period of January 1996 to August 2007. To this end, two methods are applied. The first consists of breaking the variance of rids down into relative purchasing power pariety and uncovered interest rate parity and shows that inflation differentials are the main source of rids variation; while the second method breaks down the rids and nominal interest rate differentials (nids into nominal and real shocks. Bivariate autoregressive models are estimated under particular identification conditions, having been adequately treated for the identified structural breaks. Impulse response functions and error variance decomposition result in real shocks as being the likely cause of rids.O objetivo deste artigo é investigar as causas gerais dos diferenciais da taxa de juros real (rids para um conjunto de países emergentes, para o período de janeiro de 1996 a agosto de 2007. Para tanto, duas metodologias são aplicadas. A primeira consiste em decompor a variância dos rids entre a paridade do poder de compra relativa e a paridade de juros a descoberto e mostra que os diferenciais de inflação são a fonte predominante da variabilidade dos rids; a segunda decompõe os rids e os diferenciais de juros nominais (nids em choques nominais e reais. Sob certas condições de identificação, modelos autorregressivos bivariados são estimados com tratamento adequado para as quebras estruturais identificadas e as funções de resposta ao impulso e a decomposição da variância dos erros de previsão são obtidas, resultando em evidências favoráveis a que os choques reais são a causa mais provável dos rids.

  18. Molecular Characterization of Soil Ammonia-Oxidizing Bacteria Based on the Genes Encoding Ammonia Monooxygenase

    OpenAIRE

    Alzerreca, Jose Javier

    1999-01-01

    Ammonia-oxidizing bacteria (AOB) are chemolithotrophs that oxidize ammonia/ammonium to nitrite in a two-step process to obtain energy for survival. AOB are difficult to isolate from the environment and iso lated strains may not represent the diversity in soil. A genetic database and molecular tools were developed based on the ammonia monooxygenase (AMO) encoding genes that can be used to assess the diversity of AOB that exist in soil and aquatic environments without the isolation of pure cult...

  19. Ammonia as a Suitable Fuel for Fuel Cells

    OpenAIRE

    Lan, Rong; Tao, Shanwen

    2014-01-01

    Ammonia, an important basic chemical, is produced at a scale of 150 million tons per year. Half of hydrogen produced in chemical industry is used for ammonia production. Ammonia containing 17.5 wt% hydrogen is an ideal carbon-free fuel for fuel cells. Compared to hydrogen, ammonia has many advantages. In this mini-review, the suitability of ammonia as fuel for fuel cells, the development of different types of fuel cells using ammonia as the fuel and the potential applications of ammonia fuel ...

  20. Ammonia manipulates the ammonia-oxidizing archaea and bacteria in the coastal sediment-water microcosms.

    Science.gov (United States)

    Zhang, Yan; Chen, Lujun; Dai, Tianjiao; Sun, Renhua; Wen, Donghui

    2015-08-01

    Ammonia was observed as a potential significant factor to manipulate the abundance and activity of ammonia-oxidizing microorganisms (AOMs) in water environments. For the first time, this study confirmed this phenomenon by laboratory cultivation. In a series of estuarine sediment-coastal water microcosms, we investigated the AOM's phylogenetic composition and activity change in response to ammonia concentration. Increase of ammonia concentration promoted bacterial amoA gene abundance in a linear pattern. The ratio of transcribed ammonia-oxidizing bacteria (AOB) amoA gene/ammonia-oxidizing archaea (AOA) amoA gene increased from 0.1 to 43 as NH4 (+)-N increased from less than 0.1 to 12 mg L(-1), and AOA amoA transcription was undetected under 20 mg NH4 (+)-N L(-1). The incubation of stable isotope probing (SIP) microcosms revealed a faster (13)C-NaHCO3 incorporation rate of AOA amoA gene under 0.1 mg NH4 (+)-N L(-1) and a sole (13)C-NaHCO3 utilization of the AOB amoA gene under 20 mg NH4 (+)-N L(-1). Our results indicate that ammonia concentration manipulates the structure of AOM. AOA prefers to live and perform higher amoA transcription activity than AOB in ammonia-limited water environments, and AOB tends to take the first contributor place in ammonia-rich ones. PMID:25797330

  1. Assimilation of ammonia in Paracoccus denitrificans.

    Science.gov (United States)

    Mikes, V; Chválová, H; Mátlová, L

    1991-01-01

    Two pathways serve for assimilation of ammonia in Paracoccus denitrificans. Glutamate dehydrogenase (NADP+) catalyzes the assimilation at a high NH4+ concentration. If nitrate serves as the nitrogen source, glutamate is synthesized by glutamate-ammonia ligase and glutamate synthase (NADPH). At a very low NH4+ concentration, all three enzymes are synthesized simultaneously. No direct relationship exists between glutamate dehydrogenase (NADP+) and glutamate-ammonia ligase in P. denitrificans, while the glutamate synthase (NADPH) activity changes in parallel with that of the latter enzyme. Ammonia does not influence the induction or repression of glutamate dehydrogenase (NADP+). The inner concentration of metabolites indicates a possible repression of glutamate dehydrogenase (NADP+) by the high concentration of glutamine or its metabolic products as in the case when NH4+ is formed by assimilative nitrate reduction. No direct effect of the intermediates of nitrate assimilation on the synthesis of glutamate dehydrogenase (NADP+) was observed. PMID:1688163

  2. Ammonia transformation in a biotrickling air filter

    DEFF Research Database (Denmark)

    Nielsen, Lars Peter; Nielsen, Marie Louise; Andersen, Mathias;

    2007-01-01

    measurements and model was obtained by using conventional substrate and inhibition kinetics of ammonium and nitrite oxidizing bacteria. Highest rates of ammonia removal were observed in the central section of the filter. Near the air outlet and water inlet the process was ammonia limited, while high nitrous...... acid concentrations almost excluded any biological activity near the air inlet and water outlet. Nitrous acid inhibition also stabilized pH at 6.5-7 all through the filter. Being sensitive to both ammonia and nitrous acid the nitrite oxidation process occurred mainly in the filter sections near the air...... outlet / water inlet, and only 8% of the nitrite was turned into nitrate. Water supply only exceeded evaporation by 20% but modelling indicated that additional watering would have limited effect on filter efficiency. The filter was also robust to varying loading, as a 4-fold increase in ammonia inlet...

  3. Ultrafast dynamics of electrons in ammonia.

    Science.gov (United States)

    Vöhringer, Peter

    2015-04-01

    Solvated electrons were first discovered in solutions of metals in liquid ammonia. The physical and chemical properties of these species have been studied extensively for many decades using an arsenal of electrochemical, spectroscopic, and theoretical techniques. Yet, in contrast to their hydrated counterpart, the ultrafast dynamics of ammoniated electrons remained completely unexplored until quite recently. Femtosecond pump-probe spectroscopy on metal-ammonia solutions and femtosecond multiphoton ionization spectroscopy on the neat ammonia solvent have provided new insights into the optical properties and the reactivities of this fascinating species. This article reviews the nature of the optical transition, which gives the metal-ammonia solutions their characteristic blue appearance, in terms of ultrafast relaxation processes involving bound and continuum excited states. The recombination processes following the injection of an electron via photoionization of the solvent are discussed in the context of the electronic structure of the liquid and the anionic defect associated with the solvated electron. PMID:25493716

  4. Ammonia Affects Astroglial Proliferation in Culture.

    Directory of Open Access Journals (Sweden)

    Guillermo Bodega

    Full Text Available Primary cultures of rat astroglial cells were exposed to 1, 3 and 5 mM NH4Cl for up to 10 days. Dose- and time-dependent reductions in cell numbers were seen, plus an increase in the proportion of cells in the S phase. The DNA content was reduced in the treated cells, and BrdU incorporation diminished. However, neither ammonia nor ammonia plus glutamine had any effect on DNA polymerase activity. iTRAQ analysis showed that exposure to ammonia induced a significant reduction in histone and heterochromatin protein 1 expression. A reduction in cell viability was also noted. The ammonia-induced reduction of proliferative activity in these cultured astroglial cells seems to be due to a delay in the completion of the S phase provoked by the inhibition of chromatin protein synthesis.

  5. Catalytic upgrading of lignin

    OpenAIRE

    Garza Treviño, Ricardo

    2015-01-01

    In the broadest vision to contribute to sustainability, with focus on the use of lignin as a sustainable source for the production of chemicals, experiments were performed to find which chemicals may potentially be produced from isolated (organosolv-extracted) lignin through its decomposition by hydrodeoxygenation, as well as to describe the properties and composition of the product as a whole. Catalyst screening was implemented to evaluate the optimal catalyst to obtain low molecular weight ...

  6. Sanitisation of faecal sludge by ammonia

    OpenAIRE

    Fidjeland, Jörgen

    2015-01-01

    Faecal sludge contains valuable plant nutrients and can be used as a fertiliser in agriculture, instead of being emitted as a pollutant. As this involves a risk of pathogen transmission, it is crucial to inactivate the pathogens in faecal sludge. One treatment alternative is ammonia sanitisation, as uncharged ammonia (NH₃) inactivates pathogens. The aim of this thesis was to study how the pathogen inactivation depends on treatment factors, mainly NH₃ concentration, temperature and storage tim...

  7. Probing Reversible Chemistry in Coenzyme B12-Dependent Ethanolamine Ammonia Lyase with Kinetic Isotope Effects

    OpenAIRE

    Rentergent, Julius; Scruton, Nigel S; Hay, Sam; Jones, Alex R.

    2015-01-01

    Coenzyme B12-dependent enzymes such as ethanolamine ammonia lyase have remarkable catalytic power and some unique properties that enable detailed analysis of the reaction chemistry and associated dynamics. By selectively deuterating the substrate (ethanolamine) and/or the β-carbon of the 5′-deoxyadenosyl moiety of the intrinsic coenzyme B12, it was possible to experimentally probe both the forward and reverse hydrogen atom transfers between the 5′-deoxyadenosyl radical and substrate duri...

  8. Study of Ammonia Emissions in a Ventilated Pig Pen

    OpenAIRE

    Rong, Li

    2011-01-01

    Pig productions cause a wide emission of odors, such as ammonia (NH3), hydrogen sulfide (H2S), and methane (CH4). Ammonia is one of the most important emissions for evaluating the air quality either in animal buildings or atmospheric environment. In studies of ammonia emission from animal buildings reported in literature, little effort has been made to investigate the accuracy of current Henry’s law constant for modeling ammonia mass transfer process and study ammonia emissions in a full scal...

  9. Influence of Ammonia Leaching on the Structure and Catalytic Performance of CuO/CeO2 Catalysts for Water -gas Shift Reaction%氨沥滤对 CuO/CeO2变换催化剂结构和性能的影响

    Institute of Scientific and Technical Information of China (English)

    何润霞; 赵文怡; 智科端; 武芳; 周晨亮; 刘全生

    2013-01-01

    本文以CeO2为载体,采用浸渍法制备了不同铜负载量的CuO/CeO2水煤气变换催化剂,并以其为前驱体,通过氨沥滤改变CuO/CeO2催化剂中铜负载量,利用XRD、BET、TPR和活性测试等对催化剂样品的结构及催化性能进行比较研究。结果表明,铜负载量大小是影响CuO/CeO2催化剂结构与性能的重要因素,不同铜负载量的CuO/CeO2样品经氨水沥滤后没有改变原有结晶度的变化规律及物相组成,但晶粒度均提高。 CuO负载量小于12%,氨沥滤后样品的比表面积和孔容均减小,催化活性降低。 CuO负载量大于12%,氨沥滤后样品的比表面积和孔容降低幅度较CuO负载量小于12%样品小,活性降幅很小或反而提高。%In this paper , the CuO/CeO2 water gas shift catalysts with different copper loading capacities were prepared by incipient wet impregnation while CeO 2 was used as catalyst support .With the catalysts as precursors , the ion embed-leached type CuO/CeO2 catalysts were prepared through NH 3 · H2 O leaching, by using the feature that Copper ions are liable to be leached by NH3 · H2 O.The structure and performance of the catalyst were characterized by XRD , BET and TPR, and the activities on the shift reaction were also tested .The results show that: the copper loading capacity was an important factor to the structures and properties of CuO/CeO2 catalysts.NH3 · H2 O leaching process did not change to the overall change trends of the crystallinity of samples and phase composition , but grain size of samples increased after NH 3 · H2 O leaching .When CuO loadings were less than 12%, specific surface area and pore volume of leached samples decreased , and the catalytic activity decreased , too.While CuO loadings were more than 12%, specific surface area and pore volume of leached samples also decreased , but the extent of decreasing was less than the amount that CuO loadings were less than 12%.Therefore, the

  10. Using a Hands-On Hydrogen Peroxide Decomposition Activity to Teach Catalysis Concepts to K-12 Students

    Science.gov (United States)

    Cybulskis, Viktor J.; Ribeiro, Fabio H.; Gounder, Rajamani

    2016-01-01

    A versatile and transportable laboratory apparatus was developed for middle and high school (6th-12th grade) students as part of a hands-on outreach activity to estimate catalytic rates of hydrogen peroxide decomposition from oxygen evolution rates measured by using a volumetric displacement method. The apparatus was constructed with inherent…

  11. Molecular modelling of the decomposition of NH3 over CoO(100)

    International Nuclear Information System (INIS)

    Spin-polarised density functional theory using the PBE + U approach are used to determine reaction pathways of successive NH3 dehydrogenation on the CoO(100) surface. NH3 dehydrogenation promotes noticeable displacements of the surface CoO sites, in particular due to the binding of NH2 and H species. Surface lattice O has low activity towards dehydrogenation, reflected in energy barriers that are in the range of 292 kJ mol−1 to 328 kJ mol−1. There is a preference of surface NH3 dehydrogenation to N2 rather than towards NO, due to a high-energy penalty of surface O vacancy formation. The presence of CoO in cobalt oxide catalysts not only may decline the ammonia conversion but also alter the selectivity towards N2 rather than NO. - Highlights: • Minimum reactions pathways of ammonia decomposition were studied using density functional theory. • The bonding characteristics of NHx and H on the CoO(100) surface were analysed using Layer-projected density of states. • Dehydrogenations of NH3, NH2 and NH are highly activated. • The presence of strongly bound lattice oxygen favours the ammonia decomposition towards N2

  12. Decomposition mechanism of melamine borate in pyrolytic and thermo-oxidative conditions

    Energy Technology Data Exchange (ETDEWEB)

    Hoffendahl, Carmen; Duquesne, Sophie; Fontaine, Gaëlle; Bourbigot, Serge, E-mail: serge.bourbigot@ensc-lille.fr

    2014-08-20

    Highlights: • Decomposition of melamine borate in pyrolytic and thermo-oxidative conditions was investigated. • With increasing temperature, orthoboric acid forms boron oxide releasing water. • Melamine decomposes evolving melamine, ammonia and other fragments. • Boron oxide is transformed into boron nitride and boron nitride-oxide structures through presence of ammonia. - Abstract: Decomposition mechanism of melamine borate (MB) in pyrolytic and thermo-oxidative conditions is investigated in the condensed and gas phases using solid state NMR ({sup 13}C and {sup 11}B), X-ray photoelectron spectroscopy (XPS), pyrolysis-gas chromatography–mass spectrometry (py-GCMS) and thermogravimetric analysis coupled with a Fourier transform infrared spectrometer (TGA–FTIR). It is evidenced that orthoboric acid dehydrates to metaboric and then to boron oxide. The melamine is partially sublimated. At the same time, melamine condensates, i.e., melem and melon are formed. Melon is only formed in thermo-oxidative conditions. At higher temperature, melem and melon decompose releasing ammonia which reacts with the boron oxide to form boron nitride (BN) and BNO structures.

  13. Molecular modelling of the decomposition of NH{sub 3} over CoO(100)

    Energy Technology Data Exchange (ETDEWEB)

    Shojaee, Kambiz; Haynes, Brian S.; Montoya, Alejandro, E-mail: alejandro.montoya@sydney.edu.au

    2015-04-15

    Spin-polarised density functional theory using the PBE + U approach are used to determine reaction pathways of successive NH{sub 3} dehydrogenation on the CoO(100) surface. NH{sub 3} dehydrogenation promotes noticeable displacements of the surface CoO sites, in particular due to the binding of NH{sub 2} and H species. Surface lattice O has low activity towards dehydrogenation, reflected in energy barriers that are in the range of 292 kJ mol{sup −1} to 328 kJ mol{sup −1}. There is a preference of surface NH{sub 3} dehydrogenation to N{sub 2} rather than towards NO, due to a high-energy penalty of surface O vacancy formation. The presence of CoO in cobalt oxide catalysts not only may decline the ammonia conversion but also alter the selectivity towards N{sub 2} rather than NO. - Highlights: • Minimum reactions pathways of ammonia decomposition were studied using density functional theory. • The bonding characteristics of NH{sub x} and H on the CoO(100) surface were analysed using Layer-projected density of states. • Dehydrogenations of NH{sub 3}, NH{sub 2} and NH are highly activated. • The presence of strongly bound lattice oxygen favours the ammonia decomposition towards N{sub 2}.

  14. Corrosion inhibitor for aqueous ammonia absorption system

    Science.gov (United States)

    Phillips, Benjamin A.; Whitlow, Eugene P.

    1998-09-22

    A method of inhibiting corrosion and the formation of hydrogen and thus improving absorption in an ammonia/water absorption refrigeration, air conditioning or heat pump system by maintaining the hydroxyl ion concentration of the aqueous ammonia working fluid within a selected range under anaerobic conditions at temperatures up to 425.degree. F. This hydroxyl ion concentration is maintained by introducing to the aqueous ammonia working fluid an inhibitor in an amount effective to produce a hydroxyl ion concentration corresponding to a normality of the inhibitor relative to the water content ranging from about 0.015 N to about 0.2 N at 25.degree. C. Also, working fluids for inhibiting the corrosion of carbon steel and resulting hydrogen formation and improving absorption in an ammonia/water absorption system under anaerobic conditions at up to 425.degree. F. The working fluids may be aqueous solutions of ammonia and a strong base or aqueous solutions of ammonia, a strong base, and a specified buffer.

  15. Using ammonia as a sustainable fuel

    Science.gov (United States)

    Zamfirescu, C.; Dincer, I.

    In this study, ammonia is identified as a sustainable fuel for mobile and remote applications. Similar to hydrogen, ammonia is a synthetic product that can be obtained either from fossil fuels, biomass, or other renewable sources. Some advantages of ammonia with respect to hydrogen are less expensive cost per unit of stored energy, higher volumetric energy density that is comparable with that of gasoline, easier production, handling and distribution with the existent infrastructure, and better commercial viability. Here, the possible ways to use ammonia as a sustainable fuel in internal combustion engines and fuel-cells are discussed and analysed based on some thermodynamic performance models through efficiency and effectiveness parameters. The refrigeration effect of ammonia, which is another advantage, is also included in the efficiency calculations. The study suggests that the most efficient system is based on fuel-cells which provide simultaneously power, heating and cooling and its only exhaust consists of water and nitrogen. If the cooling effect is taken into consideration, the system's effectiveness reaches 46% implying that a medium size car ranges over 500 km with 50 l fuel at a cost below 2 per 100 km. The cooling power represents about 7.2% from the engine power, being thus a valuable side benefit of ammonia's presence on-board.

  16. Livestock wastewater treatment: ammonia removal

    International Nuclear Information System (INIS)

    Livestock wastewater contains high concentration of ammonia. Removal of this inorganic species of nitrogen could be achieved through nitrification and de-nitrification. Nitrification process was conducted in the laboratory using activated sludge process with HRT of three and five days. After wastewater undergone nitrification process at Livestock Wastewater Treatment Plant the concentration of influent for N-NH4+ reduced from 400 mg/l to 0 mg/l and concentration of N-NO3- increased from 11 mg/l to 300 mg/l. Nitrification using lab-scale activated sludge process also recorded similar result. Concentration of N-NH4+ reduced from 400 mg/l to 2 mg/l and 380 mg/l to 1.1 mg/l for HRT=5 days and HRT=3 days respectively. N-NO3- was increased from 11 mg/l to 398 mg/l and 14 mg/l to 394 mg/l for HRT=5 days and HRT=3 days, respectively. However changes of N-NH4+ and N=NO3- were not observed using gamma irradiation. The combination of gamma irradiation with activated sludge process indicated difference and its contribution is still investigated

  17. Ultra Low NOx Catalytic Combustion for IGCC Power Plants

    Energy Technology Data Exchange (ETDEWEB)

    Shahrokh Etemad; Benjamin Baird; Sandeep Alavandi; William Pfefferle

    2008-03-31

    to be active in ammonia reduction in fuel allowing potential reductions in the burner NOx production. These reductions of NOx emissions and expanded alternative fuel capability make the rich catalytic combustor uniquely situated to provide reductions in capital costs through elimination of requirements for SCR, operating costs through reduction in need for NOx abating dilution, SCR operating costs, and need for co-firing fuels allowing use of lower value but more available fuels, and efficiency of an engine through reduction in dilution flows.

  18. Sulfate Promoted Zirconia as Promising Alkali-Resistant Support for Catalytic NOx Removal

    OpenAIRE

    Due-Hansen, Johannes; Kustov, Arkadii; Christensen, Claus H.; Fehrmann, Rasmus

    2007-01-01

    The use of bio-fuels as alternatives to traditional fossil fuels has attracted much attention recent years since bio-fuels belong to a family of renewable types of energy sources and do not contribute to the green-house effect. Selective catalytic reduction (SCR) of NOx with ammonia as reductant is the most efficient method to eliminate NOx from flue gases in stationary sources. The traditional SCR catalyst suffers significant deactivation with time due to the presence of relative large amoun...

  19. Catalytic thermal barrier coatings

    Science.gov (United States)

    Kulkarni, Anand A.; Campbell, Christian X.; Subramanian, Ramesh

    2009-06-02

    A catalyst element (30) for high temperature applications such as a gas turbine engine. The catalyst element includes a metal substrate such as a tube (32) having a layer of ceramic thermal barrier coating material (34) disposed on the substrate for thermally insulating the metal substrate from a high temperature fuel/air mixture. The ceramic thermal barrier coating material is formed of a crystal structure populated with base elements but with selected sites of the crystal structure being populated by substitute ions selected to allow the ceramic thermal barrier coating material to catalytically react the fuel-air mixture at a higher rate than would the base compound without the ionic substitutions. Precious metal crystallites may be disposed within the crystal structure to allow the ceramic thermal barrier coating material to catalytically react the fuel-air mixture at a lower light-off temperature than would the ceramic thermal barrier coating material without the precious metal crystallites.

  20. Adiabatic calorimetric decomposition studies of 50 wt.% hydroxylamine/water.

    Science.gov (United States)

    Cisneros, L O; Rogers, W J; Mannan, M S

    2001-03-19

    Calorimetric data can provide a basis for determining potential hazards in reactions, storage, and transportation of process chemicals. This work provides calorimetric data for the thermal decomposition behavior in air of 50wt.% hydroxylamine/water (HA), both with and without added stabilizers, which was measured in closed cells with an automatic pressure tracking adiabatic calorimeter (APTAC). Among the data provided are onset temperatures, reaction order, activation energies, pressures of noncondensable products, thermal stability at 100 degrees C, and the effect of HA storage time. Discussed also are the catalytic effects of carbon steel, stainless steel, stainless steel with silica coating, inconel, titanium, and titanium with silica coating on the reaction self-heat rates and onset temperatures. In borosilicate glass cells, HA was relatively stable at temperatures up to 133 degrees C, where the HA decomposition self-heat rate reached 0.05 degrees C/min. The added stabilizers appeared to reduce HA decomposition rates in glass cells and at ambient temperatures. The tested metals and metal surfaces coated with silica acted as catalysts to lower the onset temperatures and increase the self-heat rates.

  1. Distributed k-Core Decomposition

    CERN Document Server

    Montresor, Alberto; Miorandi, Daniele

    2011-01-01

    Among the novel metrics used to study the relative importance of nodes in complex networks, k-core decomposition has found a number of applications in areas as diverse as sociology, proteinomics, graph visualization, and distributed system analysis and design. This paper proposes new distributed algorithms for the computation of the k-core decomposition of a network, with the purpose of (i) enabling the run-time computation of k-cores in "live" distributed systems and (ii) allowing the decomposition, over a set of connected machines, of very large graphs, that cannot be hosted in a single machine. Lower bounds on the algorithms complexity are given, and an exhaustive experimental analysis on real-world graphs is provided.

  2. A catalytic cracking process

    Energy Technology Data Exchange (ETDEWEB)

    Degnan, T.F.; Helton, T.E.

    1995-07-20

    Heavy oils are subjected to catalytic cracking in the absence of added hydrogen using a catalyst containing a zeolite having the structure of ZSM-12 and a large-pore crystalline zeolite having a Constraint Index less than about 1. The process is able to effect a bulk conversion of the oil at the same time yielding a higher octane gasoline and increased light olefin content. (author)

  3. Pants decompositions of random surfaces

    CERN Document Server

    Guth, Larry; Young, Robert

    2010-01-01

    Our goal is to show, in two different contexts, that "random" surfaces have large pants decompositions. First we show that there are hyperbolic surfaces of genus $g$ for which any pants decomposition requires curves of total length at least $g^{7/6 - \\epsilon}$. Moreover, we prove that this bound holds for most metrics in the moduli space of hyperbolic metrics equipped with the Weil-Petersson volume form. We then consider surfaces obtained by randomly gluing euclidean triangles (with unit side length) together and show that these surfaces have the same property.

  4. Ammonia and hydrazine. Transition-metal-catalyzed hydroamination and metal-free catalyzed functionalization

    Energy Technology Data Exchange (ETDEWEB)

    Bertrand, Guy [Univ. of California, San Diego, CA (United States)

    2012-06-29

    The efficient and selective preparation of organic molecules is critical for mankind. For the future, it is of paramount importance to find catalysts able to transform abundant and cheap feedstocks into useful compounds. Acyclic and heterocyclic nitrogen-containing derivatives are common components of naturally occurring compounds, agrochemicals, cosmetics, and pharmaceuticals; they are also useful intermediates in a number of industrial processes. One of the most widely used synthetic strategies, allowing the formation of an N-C bond, is the addition of an N-H bond across a carbon-carbon multiple bond, the so-called hydroamination reaction. This chemical transformation fulfills the principle of “green chemistry” since it ideally occurs with 100% atom economy. Various catalysts have been found to promote this reaction, although many limitations remain; one of the most prominent is the lack of methods that permit the use of NH3 and NH2NH2 as the amine partners. In fact, ammonia and hydrazine have rarely succumbed to homogeneous catalytic transformations. Considering the low cost and abundance of ammonia (136 million metric tons produced in 2011) and hydrazine, catalysts able to improve the reactivity and selectivity of the NH3- and NH2NH2-hydroamination reaction, and more broadly speaking the functionalization of these chemicals, are highly desirable. In the last funded period, we discovered the first homogeneous catalysts able to promote the hydroamination of alkynes and allenes with ammonia and the parent hydrazine. The key feature of our catalytic systems is that the formation of catalytically inactive Werner complexes is reversible, in marked contrast to most of the known ammonia and hydrazine transition metal complexes. This is due to the peculiar electronic properties of our neutral ancillary ligands, especially their strong donating capabilities. However, our catalysts currently require

  5. 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

  6. Ammonia transformations and abundance of ammonia oxidizers in a clay soil underlying a manure pond.

    Science.gov (United States)

    Sher, Yonatan; Baram, Shahar; Dahan, Ofer; Ronen, Zeev; Nejidat, Ali

    2012-07-01

    Unlined manure ponds are constructed on clay soil worldwide to manage farm waste. Seepage of ammonia-rich liquor into underlying soil layers contributes to groundwater contamination by nitrate. To identify the possible processes that lead to the production of nitrate from ammonia in this oxygen-limited environment, we studied the diversity and abundance of ammonia-transforming microorganisms under an unlined manure pond. The numbers of ammonia-oxidizing bacteria and anammox bacteria were most abundant in the top of the soil profile and decreased significantly with depth (0.5 m), correlating with soil pore-water ammonia concentrations and soil ammonia concentrations, respectively. On the other hand, the numbers of ammonia-oxidizing archaea were relatively constant throughout the soil profile (10(7) amoA copies per g(soil)). Nitrite-oxidizing bacteria were detected mainly in the top 0.2 m. The results suggest that nitrate accumulation in the vadose zone under the manure pond could be the result of complete aerobic nitrification (ammonia oxidation to nitrate) and could exist as a byproduct of anammox activity. While the majority of the nitrogen was removed within the 0.5-m soil section, possibly by combined anammox and heterotrophic denitrification, a fraction of the produced nitrate leached into the groundwater.

  7. Water Quality of NPP Secondary Side with Combined Water Chemistry of Ammonia and Ethanolamine

    International Nuclear Information System (INIS)

    Ammonia (AM) and Ethanolamine (ETA), as pH control additive agents, were injected to the secondary side in a Korean NPP for the even pH in the entire secondary system including the wet region and the condensate. Ammonia and ETA are dominant in the vapor and liquid phases, respectively, since the former and latter are more and less volatile than water in the temperature range of 30 to 300 . pH of 9.5 to 9.7 was maintained in the water-steam cycle at the concentrations of ammonia with ∼1.0 ppm and ETA of ∼1.8 ppm. From the standpoint of corrosion, i.g, concentration of Fe, the water quality of secondary side was improved by the combined water treatment of ammonia and ETA, compared to all volatile treatment of ammonia. The electrical conductivity was increased from 6 to 10 μS/cm due to the presence of organic carboxylates produced by the decomposition of ETA. ETA was broken down by <5% in steam generator and converted into formate, acetate, and glycolate, among which acetate was largely formed. But inorganic ions such as Na+, Cl-, and SO42- are not changed because their ingress was not made and the selectivity of resin over those ions was not fairly altered. The runtime of demineralizer in steam generator blowdown was shortened by a third for a mixture of ammonia and ETA. Most of Fe was originated from the shell side of heat exchangers including the condenser as a result of corrosion. Fe was only eliminated by ion exchange demineralizers, i.e., 46% at CPP and 3% at SG BD and 70% of Fe oxides were accumulated at the steam generator, on the basis of Fe concentration at the final feedwater. In conclusion, ETA is preferable to ammonia for the enhancement of pH in the liquid phase of water-steam mixture such as the shell side of heat exchanger and also the full-flow operation of CPP is more desirable than partial-flow operation for the improved removal of corrosion products, regardless of hydrogen- or amine-type operation. (authors)

  8. Facile synthesis and catalytic property of porous tin dioxide nanostructures.

    Science.gov (United States)

    Zhao, Qingrui; Zhang, Zhigao; Dong, Ting; Xie, Yi

    2006-08-10

    Porous tin dioxide (SnO(2)) nanostructures consisting of nanoplates are prepared through thermal decomposition of the mixed solution composed of dibutyltin dilaurate and acetic acid. The aggregations of the nanoplates give rise to large macropores with the size of about 100-300 nm. These nanoplates have a wormhole-like porous structure with the size of about 4 nm and possess high surface area. X-ray powder diffraction, transmission electron microscopy, scanning electron microscopy, infrared spectroscopy, and nitrogen sorption have been employed to characterize the obtained porous structures. It is found that the obtained nanostructures exhibit excellent catalytic activity toward methanol decomposition. Such porous structures with high surface area have promising industrial applications as catalysts. PMID:16884229

  9. On the decomposition of forces

    Directory of Open Access Journals (Sweden)

    Dong Eui Chang

    2014-01-01

    Full Text Available We show that any continuously differentiable force is decomposed into the sum of a Rayleigh force and a gyroscopic force. We also extend this result to piecewise continuously differentiable forces. Our result improves the result on the decomposition of forces in a book by David Merkin and further extends it to piecewise continuously differentiable forces.

  10. Microbial interactions during carrion decomposition

    Science.gov (United States)

    This addresses the microbial ecology of carrion decomposition in the age of metagenomics. It describes what is known about the microbial communities on carrion, including a brief synopsis about the communities on other organic matter sources. It provides a description of studies using state-of-the...

  11. Modular Decomposition of Boolean Functions

    NARCIS (Netherlands)

    J.C. Bioch (Cor)

    2002-01-01

    textabstractModular decomposition is a thoroughly investigated topic in many areas such as switching theory, reliability theory, game theory and graph theory. Most appli- cations can be formulated in the framework of Boolean functions. In this paper we give a uni_ed treatment of modular decompositio

  12. Process design for wastewater treatment: catalytic ozonation of organic pollutants.

    Science.gov (United States)

    Derrouiche, S; Bourdin, D; Roche, P; Houssais, B; Machinal, C; Coste, M; Restivo, J; Orfão, J J M; Pereira, M F R; Marco, Y; Garcia-Bordeje, E

    2013-01-01

    Emerging micropollutants have been recently the target of interest for their potential harmful effects in the environment and their resistance to conventional water treatments. Catalytic ozonation is an advanced oxidation process consisting of the formation of highly reactive radicals from the decomposition of ozone promoted by a catalyst. Nanocarbon materials have been shown to be effective catalysts for this process, either in powder form or grown on the surface of a monolithic structure. In this work, carbon nanofibers grown on the surface of a cordierite honeycomb monolith are tested as catalyst for the ozonation of five selected micropollutants: atrazine (ATZ), bezafibrate, erythromycin, metolachlor, and nonylphenol. The process is tested both in laboratorial and real conditions. Later on, ATZ was selected as a target pollutant to further investigate the role of the catalytic material. It is shown that the inclusion of a catalyst improves the mineralization degree compared to single ozonation. PMID:24056437

  13. NOx Direct Decomposition: Potentially Enhanced Thermodynamics and Kinetics on Chemically Modified Ferroelectric Surfaces

    Science.gov (United States)

    Kakekhani, Arvin; Ismail-Beigi, Sohrab

    2014-03-01

    NOx are regulated pollutants produced during automotive combustion. As part of an effort to design catalysts for NOx decomposition that operate in oxygen rich environment and permit greater fuel efficiency, we study chemistry of NOx on (001) ferroelectric surfaces. Changing the polarization at such surfaces modifies electronic properties and leads to switchable surface chemistry. Using first principles theory, our previous work has shown that addition of catalytic RuO2 monolayer on ferroelectric PbTiO3 surface makes direct decomposition of NO thermodynamically favorable for one polarization. Furthermore, the usual problem of blockage of catalytic sites by strong oxygen binding is overcome by flipping polarization that helps desorb the oxygen. We describe a thermodynamic cycle for direct NO decomposition followed by desorption of N2 and O2. We provide energy barriers and transition states for key steps of the cycle as well as describing their dependence on polarization direction. We end by pointing out how a switchable order parameter of substrate,in this case ferroelectric polarization, allows us to break away from some standard compromises for catalyst design(e.g. the Sabatier principle). This enlarges the set of potentially catalytic metals. Primary support from Toyota Motor Engineering and Manufacturing, North America, Inc.

  14. Quantitative comparison of power decompositions

    Energy Technology Data Exchange (ETDEWEB)

    Erhan Balci, M.; Hakan Hocaoglu, M. [Gebze Institute of Technology, Department of Electronics Engineering, Kocaeli 41400 (Turkey)

    2008-03-15

    This paper presents a comparison on power decompositions in a simple single phase circuit with nonsinusoidal waveforms of voltage and/or currents by giving particular emphasis to Reactive Power compensation. The experimental circuit is analysed by using exact analytical expressions for current and voltages determined via considering source impedance and nonlinearity, which is introduced due to supply side harmonics. Results demonstrate that; power decompositions proposed by Kusters and Moore, Fryze, Shepherd and Zakikhani, Sharon, and Czarnecki provide correct information regarding Power Factor improvement with passive compensation in nonsinusoidal voltage source-linear load, nonsinusoidal voltage source-nonlinear load and sinusoidal voltage source-nonlinear load cases. In these cases, Reactive component of Kusters and Moore's power decomposition can completely be compensated when Power Factor is maximum if there is no resonance or significant changes on load voltages in the case of compensation capacitance is inserted. The Reactive components of Fryze, Shepherd and Zakikhani, Sharon, Czarnecki's power decompositions attain minimum value when power factor is maximum. Furthermore, Kusters and Moore's Reactive Power could directly be related to the power of optimum compensation capacitance. On the other hand, power decompositions proposed by Budeanu, Kimbark and Depenbrock do not provide any useful information about optimum Reactive Power compensation with a basic capacitance in the cases nonsinusoidal voltage source-linear load and nonsinusoidal voltage source-nonlinear load although they can completely be compensated in these cases. An important observation is that; Distortion Powers of Budeanu and Kimbark, and Depenbrock's Residual Power have compensable parts; on the other hand, Kusters and Moore's Residual Reactive Power, Sharon's Complementary Power, Depenbrock's In Phase Power and Czarnecki's Scattered Power are almost

  15. Production of hydrogen by superadiabatic decomposition of hydrogen sulfide

    Energy Technology Data Exchange (ETDEWEB)

    Slimane, R.B.; Lau, F.S.; Dihu, R. [Gas Technology Inst., Des Plaines, IL (United States); Bingue, J.P.; Saveliev, A.V.; Fridman, A.A.; Kennedy, L.A. [Illinois Univ., Chicago, IL (United States)

    2002-07-01

    It is expected that hydrogen will become the fuel of choice for advanced technologies. Hydrogen is currently used as feedstock in the synthesis of ammonia and methanol, in the desulfurization and hydrocracking at oil refineries, and in the upgrading of hydrocarbon resources such as heavy oil and coal. Hydrogen sulfide (H{sub 2}S) is regarded as a mineral from which both hydrogen and sulfur can be extracted. Since there are large amounts of H{sub 2}S available worldwide, significant research has gone into the development of converting hydrogen sulfide into hydrogen through thermal decomposition. The high temperature required for the reaction, however, makes the approach impractical. This paper presents results of a study using a new approach to overcome the limitations of thermal decomposition. In this newly developed process, operation at very high temperatures is possible and economical through oxidation of part of the H{sub 2}S to provide the energy needed for the decomposition reaction. Partial oxidation is carried out in the presence of an inert, porous, high-capacity medium and the heat exchange results in flame temperatures that exceed the adiabatic flame temperature of the gas mixture. This process is less stringent than the Claus process because of the required feed gas conditioning. SO{sub 2} emissions inevitably form because part of the H{sub 2}S is oxidized to generate heat. However, SO{sub 2} is not expected to form to a significant degree. It was concluded that the product/byproduct separation schemes need to be examined further to have a better idea regarding the cost of hydrogen production from this process. 6 refs., 5 figs.

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

    Institute of Scientific and Technical Information of China (English)

    YANG Min; WANG Shu-bo

    2016-01-01

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

  17. Selective catalytic reduction of NO in a reverse-flow reactor: Modelling and experimental validation

    International Nuclear Information System (INIS)

    Highlights: • Reverse-flow reactors easily overcome feed concentration disturbances. • Central feeding improves ammonia adsorption in reverse-flow reactors. • Dynamic heterogeneous model validated with bench-scale experiments. • Optimum reverse-flow reactor design improves efficiency and reduces reactor size. - Abstract: The abatement of nitrogen oxides produced in combustion processes and in the chemical industry requires efficient and reliable technologies capable of fulfilling strict environmental regulations. Selective catalytic reduction (SCR) with ammonia in fixed-bed (monolithic) reactors has stood out among other techniques in the last decades. In this work, the use of reverse-flow reactors, operated under the forced un-steady state generated by the periodic reversal of the flow direction, is studied for improving the SCR performance. This reactor can take advantage of ammonia adsorption in the catalyst to enhance concentration profiles in the reactor, increasing reaction rate, efficiency and reducing the emission of un-reacted ammonia. The process has been studied experimentally in a bench-scale device using a commercial monolithic catalyst. The optimum operating conditions, best ammonia feed configuration (side or central) and capacity of the reactor to deal with feed concentration disturbances is analysed. The experiments have also been used for validating a mathematical model of the reactor based on mass conservation equations, and the model has been used to design a full-size reverse-flow reactor able of operating at industrial conditions

  18. Multi-component removal in flue gas by aqua ammonia

    Science.gov (United States)

    Yeh, James T.; Pennline, Henry W.

    2007-08-14

    A new method for the removal of environmental compounds from gaseous streams, in particular, flue gas streams. The new method involves first oxidizing some or all of the acid anhydrides contained in the gas stream such as sulfur dioxide (SO.sub.2) and nitric oxide (NO) and nitrous oxide (N.sub.2O) to sulfur trioxide (SO.sub.3) and nitrogen dioxide (NO.sub.2). The gas stream is subsequently treated with aqua ammonia or ammonium hydroxide which captures the compounds via chemical absorption through acid-base or neutralization reactions. The products of the reactions can be collected as slurries, dewatered, and dried for use as fertilizers, or once the slurries have been dewatered, used directly as fertilizers. The ammonium hydroxide can be regenerated and recycled for use via thermal decomposition of ammonium bicarbonate, one of the products formed. There are alternative embodiments which entail stoichiometric scrubbing of nitrogen oxides and sulfur oxides with subsequent separate scrubbing of carbon dioxide.

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

    Science.gov (United States)

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

    2016-09-01

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

  20. Anatase-brookite mixed phase nano TiO2 catalyzed homolytic decomposition of ammonium nitrate.

    Science.gov (United States)

    Vargeese, Anuj A; Muralidharan, Krishnamurthi

    2011-09-15

    Compared to the conventional ammonium perchlorate based solid rocket propellants, burning of ammonium nitrate (AN) based propellants produce environmentally innocuous combustion gases. Application of AN as propellant oxidizer is restricted due to low reactivity and low energetics besides its near room temperature polymorphic phase transition. In the present study, anatase-brookite mixed phase TiO(2) nanoparticles (~ 10 nm) are synthesized and used as catalyst to enhance the reactivity of the environmental friendly propellant oxidizer ammonium nitrate. The activation energy required for the decomposition reactions, computed by differential and non-linear integral isoconversional methods are used to establish the catalytic activity. Presumably, the removal of NH(3) and H(2)O, known inhibitors of ammonium nitrate decomposition reaction, due to the surface reactions on active surface of TiO(2) changes the decomposition pathway and thereby the reactivity.

  1. Gini Decomposition by Gender :Turkish Case

    OpenAIRE

    Kaya, Ezgi; Senesen, Umit

    2010-01-01

    The aim of this paper is to reveal the gender inequalities in income distribution for Turkey by using decomposition of Gini coefficient, a common income inequality measure. A new decomposition method, Dagum's approach for decomposition of the Gini coefficient is used in the study. In the analysis, the decomposition of the Gini coefficient by gender is applied to Turkish individuals twice. First Gini coefficient for total disposable income is decomposed to examine the gender disparities in ind...

  2. Hydrazine borane-induced destabilization of ammonia borane, and vice versa

    Energy Technology Data Exchange (ETDEWEB)

    Petit, Jean-Fabien; Moussa, Georges [IEM (Institut Europeen des Membranes), UMR 5635 (CNRS-ENSCM-UM2), Universite Montpellier 2, Place E. Bataillon, F-34095 Montpellier (France); Demirci, Umit B., E-mail: umit.demirci@um2.fr [IEM (Institut Europeen des Membranes), UMR 5635 (CNRS-ENSCM-UM2), Universite Montpellier 2, Place E. Bataillon, F-34095 Montpellier (France); Toche, François; Chiriac, Rodica [Université Lyon 1, CNRS, UMR 5615, Laboratoire des Multimatériaux et Interfaces, 43 boulevard du 11 Novembre 1918, F-69622 Villeurbanne (France); Miele, Philippe [IEM (Institut Europeen des Membranes), UMR 5635 (CNRS-ENSCM-UM2), Universite Montpellier 2, Place E. Bataillon, F-34095 Montpellier (France)

    2014-08-15

    Graphical abstract: - Highlights: • Hydrazine borane and ammoniaborane (mole ratio 1:1) destabilize each other. • This is characterized by a melting point at ∼30 °C and decomposition into hydrazine. • Also, some hydrogen H{sub 2} is “explosively” liberated at around 90 °C. • The mixture can be however stabilized into a potential hydrogen storage material. • This hydrogen storage material dehydrogenates up to 300 °C to form boron nitride. - Abstract: In the field of solid-state chemical hydrogen storage, ammonia borane NH{sub 3}BH{sub 3} has been widely studied while hydrazine borane N{sub 2}H{sub 4}BH{sub 3} can be considered as a “novel” material. In the present work, we investigated the behaviour of these boranes when mixed together in a mole ratio of 1:1. Hydrazine borane and ammonia borane destabilize each other. Though stable at 20–25 °C, the mixture melts at ∼30 °C and then undergoes significant decomposition, with desorption of hydrogen H{sub 2} and hydrazine N{sub 2}H{sub 4} from 67 °C. This is explained by the fact that the presence of hydrazine borane disrupts the H{sup δ+}⋯H{sup δ−} network of ammonia borane, and vice versa; the mixture is then much less stable than the pristine boranes. The mixture can nevertheless be stabilized (by heat- or vacuum-treatment and thus extraction of evolving hydrogen and hydrazine), making the as-obtained solid a potential chemical hydrogen storage material. Over the range 25–300 °C, it is able to release ca. 11.4 wt% of almost pure H{sub 2}. Furthermore forms boron nitride as the solid residue, at temperatures as low as 300 °C.

  3. Radiation decomposition of alcohols and chloro phenols in micellar systems; Descomposicion por irradiacion de alcoholes y clorofenoles en sistemas micelares

    Energy Technology Data Exchange (ETDEWEB)

    Moreno A, J

    1998-12-31

    The effect of surfactants on the radiation decomposition yield of alcohols and chloro phenols has been studied with gamma doses of 2, 3, and 5 KGy. These compounds were used as typical pollutants in waste water, and the effect of the water solubility, chemical structure, and the nature of the surfactant, anionic or cationic, was studied. The results show that anionic surfactant like sodium dodecylsulfate (SDS), improve the radiation decomposition yield of ortho-chloro phenol, while cationic surfactant like cetyl trimethylammonium chloride (CTAC), improve the radiation decomposition yield of butyl alcohol. A similar behavior is expected for those alcohols with water solubility close to the studied ones. Surfactant concentrations below critical micellar concentration (CMC), inhibited radiation decomposition for both types of alcohols. However radiation decomposition yield increased when surfactant concentrations were bigger than the CMC. Aromatic alcohols decomposition was more marked than for linear alcohols decomposition. On a mixture of alcohols and chloro phenols in aqueous solution the radiation decomposition yield decreased with increasing surfactant concentration. Nevertheless, there were competitive reactions between the alcohols, surfactants dimers, hydroxyl radical and other reactive species formed on water radiolysis, producing a catalytic positive effect in the decomposition of alcohols. Chemical structure and the number of carbons were not important factors in the radiation decomposition. When an alcohol like ortho-chloro phenol contained an additional chlorine atom, the decomposition of this compound was almost constant. In conclusion the micellar effect depend on both, the nature of the surfactant (anionic or cationic) and the chemical structure of the alcohols. The results of this study are useful for wastewater treatment plants based on the oxidant effect of the hydroxyl radical, like in advanced oxidation processes, or in combined treatment such as

  4. Gauss decomposition for quantum groups and duality

    CERN Document Server

    Damaskinsky, E V; Lyakhovsky, V D; Sokolov, M A

    1995-01-01

    The Gauss decomposition of quantum groups and supergroups are considered. The main attention is paid to the R-matrix formulation of the Gauss decomposition and its properties as well as its relation to the contraction procedure. Duality aspects of the Gauss decomposition are also touched. For clarity of exposition a few simple examples are considered in some details.

  5. Nanostructured Ni2 P as a Robust Catalyst for the Hydrolytic Dehydrogenation of Ammonia-Borane.

    Science.gov (United States)

    Peng, Cheng-Yun; Kang, Lei; Cao, Shuang; Chen, Yong; Lin, Zhe-Shuai; Fu, Wen-Fu

    2015-12-21

    Ammonia-borane (AB) is a promising chemical hydrogen-storage material. However, the development of real-time, efficient, controllable, and safe methods for hydrogen release under mild conditions is a challenge in the large-scale use of hydrogen as a long-term solution for future energy security. A new class of low-cost catalytic system is presented that uses nanostructured Ni2 P as catalyst, which exhibits excellent catalytic activity and high sustainability toward hydrolysis of ammonia-borane with the initial turnover frequency of 40.4 mol(H2)  mol(Ni2P) (-1)  min(-1) under air atmosphere and at ambient temperature. This value is higher than those reported for noble-metal-free catalysts, and the obtained Arrhenius activation energy (Ea =44.6 kJ mol(-1) ) for the hydrolysis reaction is comparable to Ru-based bimetallic catalysts. A clearly mechanistic analysis of the hydrolytic reaction of AB based on experimental results and a density functional theory calculation is presented. PMID:26545954

  6. Enrichment of high ammonia tolerant methanogenic culture

    DEFF Research Database (Denmark)

    Fotidis, Ioannis; Karakashev, Dimitar Borisov; Proietti, Nicolas;

    of the current study was to isolate and identify methanogenic cultures tolerant to high ammonia concentrations. A mixed methanogenic population was stepwise exposed to ammonia concentrations (1 to 9.26 g NH4+-N L-1) during an enrichment process with successive batch cultivations. The methanogenic population...... was derived from a full scale biogas reactor (Hashøj, Denmark), fed with 75% animal manure and 25% food industries organic waste. Basal anaerobic medium was used for the enrichment along with sodium acetate (1 g HAc L-1) as a carbon source. Fluorescence insitu hybridization (FISH) was used to determine...... microbial community composition. The outcome of the enrichment process was a mesophilic aceticlastic methanogenic enriched culture able to withstand high ammonia loads and utilize acetate and form methane stoichiometrically. FISH analysis showed that the methanogens of the enriched culture belonged...

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

    Science.gov (United States)

    Rodriguez, JoséA.; Wayne Goodman, D.

    1991-11-01

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

  8. Nonlinear mode decomposition: a noise-robust, adaptive decomposition method.

    Science.gov (United States)

    Iatsenko, Dmytro; McClintock, Peter V E; Stefanovska, Aneta

    2015-09-01

    The signals emanating from complex systems are usually composed of a mixture of different oscillations which, for a reliable analysis, should be separated from each other and from the inevitable background of noise. Here we introduce an adaptive decomposition tool-nonlinear mode decomposition (NMD)-which decomposes a given signal into a set of physically meaningful oscillations for any wave form, simultaneously removing the noise. NMD is based on the powerful combination of time-frequency analysis techniques-which, together with the adaptive choice of their parameters, make it extremely noise robust-and surrogate data tests used to identify interdependent oscillations and to distinguish deterministic from random activity. We illustrate the application of NMD to both simulated and real signals and demonstrate its qualitative and quantitative superiority over other approaches, such as (ensemble) empirical mode decomposition, Karhunen-Loève expansion, and independent component analysis. We point out that NMD is likely to be applicable and useful in many different areas of research, such as geophysics, finance, and the life sciences. The necessary matlab codes for running NMD are freely available for download.

  9. Nonlinear mode decomposition: A noise-robust, adaptive decomposition method

    Science.gov (United States)

    Iatsenko, Dmytro; McClintock, Peter V. E.; Stefanovska, Aneta

    2015-09-01

    The signals emanating from complex systems are usually composed of a mixture of different oscillations which, for a reliable analysis, should be separated from each other and from the inevitable background of noise. Here we introduce an adaptive decomposition tool—nonlinear mode decomposition (NMD)—which decomposes a given signal into a set of physically meaningful oscillations for any wave form, simultaneously removing the noise. NMD is based on the powerful combination of time-frequency analysis techniques—which, together with the adaptive choice of their parameters, make it extremely noise robust—and surrogate data tests used to identify interdependent oscillations and to distinguish deterministic from random activity. We illustrate the application of NMD to both simulated and real signals and demonstrate its qualitative and quantitative superiority over other approaches, such as (ensemble) empirical mode decomposition, Karhunen-Loève expansion, and independent component analysis. We point out that NMD is likely to be applicable and useful in many different areas of research, such as geophysics, finance, and the life sciences. The necessary matlab codes for running NMD are freely available for download.

  10. Effect of dietary protein restriction on renal ammonia metabolism.

    Science.gov (United States)

    Lee, Hyun-Wook; Osis, Gunars; Handlogten, Mary E; Guo, Hui; Verlander, Jill W; Weiner, I David

    2015-06-15

    Dietary protein restriction has multiple benefits in kidney disease. Because protein intake is a major determinant of endogenous acid production, it is important that net acid excretion change in parallel during protein restriction. Ammonia is the primary component of net acid excretion, and inappropriate ammonia excretion can lead to negative nitrogen balance. Accordingly, we examined ammonia excretion in response to protein restriction and then we determined the molecular mechanism of the changes observed. Wild-type C57Bl/6 mice fed a 20% protein diet and then changed to 6% protein developed an 85% reduction in ammonia excretion within 2 days, which persisted during a 10-day study. The expression of multiple proteins involved in renal ammonia metabolism was altered, including the ammonia-generating enzymes phosphate-dependent glutaminase (PDG) and phosphoenolpyruvate carboxykinase (PEPCK) and the ammonia-metabolizing enzyme glutamine synthetase. Rhbg, an ammonia transporter, increased in expression in the inner stripe of outer medullary collecting duct intercalated cell (OMCDis-IC). However, collecting duct-specific Rhbg deletion did not alter the response to protein restriction. Rhcg deletion did not alter ammonia excretion in response to dietary protein restriction. These results indicate 1) dietary protein restriction decreases renal ammonia excretion through coordinated regulation of multiple components of ammonia metabolism; 2) increased Rhbg expression in the OMCDis-IC may indicate a biological role in addition to ammonia transport; and 3) Rhcg expression is not necessary to decrease ammonia excretion during dietary protein restriction. PMID:25925252

  11. Novel Catalytic Membrane Reactors

    Energy Technology Data Exchange (ETDEWEB)

    Stuart Nemser, PhD

    2010-10-01

    There are many industrial catalytic organic reversible reactions with amines or alcohols that have water as one of the products. Many of these reactions are homogeneously catalyzed. In all cases removal of water facilitates the reaction and produces more of the desired chemical product. By shifting the reaction to right we produce more chemical product with little or no additional capital investment. Many of these reactions can also relate to bioprocesses. Given the large number of water-organic compound separations achievable and the ability of the Compact Membrane Systems, Inc. (CMS) perfluoro membranes to withstand these harsh operating conditions, this is an ideal demonstration system for the water-of-reaction removal using a membrane reactor. Enhanced reaction synthesis is consistent with the DOE objective to lower the energy intensity of U.S. industry 25% by 2017 in accord with the Energy Policy Act of 2005 and to improve the United States manufacturing competitiveness. The objective of this program is to develop the platform technology for enhancing homogeneous catalytic chemical syntheses.

  12. Ammonia emission time profiles based on manure transport data improve ammonia modelling across north western Europe

    Science.gov (United States)

    Hendriks, C.; Kranenburg, R.; Kuenen, J. J. P.; Van den Bril, B.; Verguts, V.; Schaap, M.

    2016-04-01

    Accurate modelling of mitigation measures for nitrogen deposition and secondary inorganic aerosol (SIA) episodes requires a detailed representation of emission patterns from agriculture. In this study the meteorological influence on the temporal variability of ammonia emissions from livestock housing and application of manure and fertilizer are included in the chemistry transport model LOTOS-EUROS. For manure application, manure transport data from Flanders (Belgium) were used as a proxy to derive the emission variability. Using improved ammonia emission variability strongly improves model performance for ammonia, mainly by a better representation of the spring maximum. The impact on model performance for SIA was negligible as explained by the limited, ammonia rich region in which the emission variability was updated. The contribution of Flemish agriculture to modelled annual mean ammonia and SIA concentrations in Flanders were quantified at respectively 7-8 and 1-2 μg/m3. A scenario study was performed to investigate the effects of reducing ammonia emissions from manure application during PM episodes by 75%, yielding a maximum reduction in modelled SIA levels of 1-3 μg/m3 during episodes. Year-to-year emission variability and a soil module to explicitly model the emission process from manure and fertilizer application are needed to further improve the modelling of the ammonia budget.

  13. Hydrothermal treatment of incineration fly ash for PCDD/Fs decomposition: the effect of iron addition.

    Science.gov (United States)

    Chen, De-Zhen; Hu, Yu-Yan; Zhang, Peng-Fei

    2012-12-01

    The catalytic effect of Fe addition on the decomposition of polychlorinated dibenzo-dioxins and polychlorinated dibenzofurans (PCDD/Fs) contained in municipal solid waste incineration (MSWI) fly ash during the hydrothermal process was investigated. Influencing factors, such as Fe addition mode, reaction time and cooling procedure after reaction, were tested to evaluate their effects. Experimental results indicated that Fe addition in the form of a mixture of ferrous sulphate and ferric sulphate enhanced decomposition of PCDD/Fs contained in the MSWI fly ash, particularly for the decomposition of 2,3,7,8-tetrachlorodibenzo-dioxin and 2,3,7,8-tetrachlorodibenzo-furan under the reaction temperature of 563 K. The decomposition rate of PCDD/Fs reached 90.33% by international toxicity equivalent (I-TEQ) when Fe was added as a mixture of ferrous and ferric sulphates by 5% (wt/wt) with the Fe (III)/Fe (II) ratio being 2; without Fe addition, the decomposition rate of PCDD/Fs was only 46.17% by I-TEQ in the same process. Fe addition in the form of ferrous sulphate alone also showed an enhancing effect on PCDD/Fs decomposition, but the associated decomposition rates were relatively lower, suggesting iron oxides formed from the mixture of ferric and ferrous sulphates are more favourable catalysts. At the same time, the cooling procedure after the hydrothermal reaction became more flexible if Fe was added in the form of a mixture of ferric and ferrous sulphates. Although a longer reaction time was helpful to increase decomposition rates of PCDD/Fs, 1 h was proved to be a reasonable time under this condition. PMID:23437649

  14. Transformation of ammonia i biological airfilters

    DEFF Research Database (Denmark)

    Nielsen, Lars Peter; Sørensen, Karen; Andersen, Mathias;

    2007-01-01

    Ammonia is a major compound in ventilation air from animal houses. In biological filters it is with varying efficiency transformed by physical, biological, and chemical processes and ends up as ammonium, nitrate, and nitrite dissolved in water and as dinitrogen, nitrous oxide and nitric oxide emi...... removal without too much energy consumption, waste water production, green house gas emission, or suppression of the filters odor removal efficiency.......Ammonia is a major compound in ventilation air from animal houses. In biological filters it is with varying efficiency transformed by physical, biological, and chemical processes and ends up as ammonium, nitrate, and nitrite dissolved in water and as dinitrogen, nitrous oxide and nitric oxide...

  15. Aqueous Ammonia soaking of digested manure fibers

    DEFF Research Database (Denmark)

    Mirtsou-Xanthopoulou, Chrysoula; Jurado, Esperanza; Skiadas, Ioannis;

    2012-01-01

    -scale anaerobic digester to enhance their methane productivity. Soaking in six different reagent concentrations in ammonia (5%, 10%, 15%, 20%, 25%, 32%) was applied for 3 days at 22°C. An overall methane yield increase from 85% to 110% was achieved compared to controls (digested manure fibers where AAS...... in methane yield as the highest concentrations tested; it is anticipated that this will result to an even lower cost for recovery and recycling of ammonia in full-scale. Moreover, the effect of 1, 3, and 5 days AAS treatment on methane production from digested fibers was investigated with 5 and 25% w...

  16. Structure of Ramie Treated by Liquid Ammonia

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    The morphology and supermolecular structures of the scoured/bleached ramie and scoured/bleached/liquid ammonia treated ramie were studied by means of scanning electron microscope, X-ray diffractometer, reverse gel permeation chromatography, etc. The results indicate that liquid ammonia treatment of the scoured/bleached ramie leads to a smoother surface, a lower crystallinity, partial crystal transformation from cellulose Ⅰ to cellulose Ⅲ, a decrease in the volume and cumulative surface area of the larger micropores and an increase in those of the smaller ones in the fiber.

  17. Chilled Ammonia Process for CO2 Capture

    DEFF Research Database (Denmark)

    Darde, Victor Camille Alfred; Thomsen, Kaj; Well, Willy J.M. van;

    2010-01-01

    The chilled ammonia process absorbs the CO2 at low temperature (2–10°C). The heat of absorption of carbon dioxide by ammonia is significantly lower than for amines. In addition, degradation problems can be avoided and a high carbon dioxide capacity is achieved. Hence, this process shows good...... and pressure up to 100bars. The results show that solid phases consisting of ammonium carbonate and bicarbonate are formed in the absorber. The heat requirements in the absorber and in the desorber have been studied. The enthalpy calculations show that a heat requirement for the desorber lower than 2GJ/ton CO2...

  18. Chilled ammonia process for CO2 capture

    DEFF Research Database (Denmark)

    Darde, Victor Camille Alfred; Thomsen, Kaj; van Well, Willy J. M;

    2009-01-01

    The chilled ammonia process absorbs the CO2 at low temperature (2-10 degrees C). The heat of absorption of carbon dioxide by ammonia is significantly lower than for amines. In addition, degradation problems can be avoided and a high carbon dioxide capacity is achieved. Hence, this process shows...... C and pressure up to 100 bars [1]. The results show that solid phases consisting of ammonium carbonate and bicarbonate are formed in the absorber. The energy requirements in the absorber and in the desorber have been studied. The enthalpy calculations show that an energy requirement for the desorber...

  19. Electrochemical ammonia production on molybdenum nitride nanoclusters

    DEFF Research Database (Denmark)

    Howalt, Jakob Geelmuyden; Vegge, Tejs

    2013-01-01

    Theoretical investigations of electrochemical production of ammonia at ambient temperature and pressure on nitrogen covered molybdenum nanoparticles are presented. Density functional theory calculations are used in combination with the computational hydrogen electrode approach to calculate the free...... energy profile for electrochemical protonation of N2 and N adatoms on cuboctahedral Mo13 nanoparticles. Pathways for electrochemical ammonia production via direct protonation of N adatoms and N2 admolecules with an onset potential as low as -0.5 V and generally lower than -0.8 V on both a nitrogen...

  20. Catalytic ramifications of steam deactivation of Y zeolites: An analysis using 2-methylhexane cracking

    Energy Technology Data Exchange (ETDEWEB)

    Yaluris, G.; Dumesic, J.A. [Univ. of Wisconsin, Madison, WI (United States); Madon, R.J. [Engelhard Corp., Iselin, NJ (United States)

    1999-08-15

    Kinetic analysis of experimental data for 2-methylhexane cracking demonstrates that trends in activity and selectivity are well simulated by adjusting a single parameter that represents the acid strength of a Y-based FCC catalyst. This acid strength may be modified via steam deactivation, and the authors have experimentally corroborated acidity changes using ammonia microcalorimetry and infrared spectroscopy. Increased severity of steam treatment reduces the number and strength of catalyst acid sites, and it leads to a reduction in the turnover frequency of all surface processes and a decrease in overall site time yield. Streaming of the catalyst does not change the fundamental chemistry involved in catalytic cracking. However, change in acidity caused by steaming alters product selectivity by changing relative rates of various catalytic cycles in the cracking process. For example, steam treatment increases olefin selectivity by favoring catalytic cycles that produce olefins.

  1. Modelling volatility by variance decomposition

    DEFF Research Database (Denmark)

    Amado, Cristina; Teräsvirta, Timo

    In this paper, we propose two parametric alternatives to the standard GARCH model. They allow the variance of the model to have a smooth time-varying structure of either additive or multiplicative type. The suggested parameterisations describe both nonlinearity and structural change in the...... conditional and unconditional variances where the transition between regimes over time is smooth. The main focus is on the multiplicative decomposition that decomposes the variance into an unconditional and conditional component. A modelling strategy for the time-varying GARCH model based on the...... multiplicative decomposition of the variance is developed. It is heavily dependent on Lagrange multiplier type misspecification tests. Finite-sample properties of the strategy and tests are examined by simulation. An empirical application to daily stock returns and another one to daily exchange rate returns...

  2. Variance decomposition in stochastic simulators

    Science.gov (United States)

    Le Maître, O. P.; Knio, O. M.; Moraes, A.

    2015-06-01

    This work aims at the development of a mathematical and computational approach that enables quantification of the inherent sources of stochasticity and of the corresponding sensitivities in stochastic simulations of chemical reaction networks. The approach is based on reformulating the system dynamics as being generated by independent standardized Poisson processes. This reformulation affords a straightforward identification of individual realizations for the stochastic dynamics of each reaction channel, and consequently a quantitative characterization of the inherent sources of stochasticity in the system. By relying on the Sobol-Hoeffding decomposition, the reformulation enables us to perform an orthogonal decomposition of the solution variance. Thus, by judiciously exploiting the inherent stochasticity of the system, one is able to quantify the variance-based sensitivities associated with individual reaction channels, as well as the importance of channel interactions. Implementation of the algorithms is illustrated in light of simulations of simplified systems, including the birth-death, Schlögl, and Michaelis-Menten models.

  3. Variance decomposition in stochastic simulators

    KAUST Repository

    Le Maître, O. P.

    2015-06-28

    This work aims at the development of a mathematical and computational approach that enables quantification of the inherent sources of stochasticity and of the corresponding sensitivities in stochastic simulations of chemical reaction networks. The approach is based on reformulating the system dynamics as being generated by independent standardized Poisson processes. This reformulation affords a straightforward identification of individual realizations for the stochastic dynamics of each reaction channel, and consequently a quantitative characterization of the inherent sources of stochasticity in the system. By relying on the Sobol-Hoeffding decomposition, the reformulation enables us to perform an orthogonal decomposition of the solution variance. Thus, by judiciously exploiting the inherent stochasticity of the system, one is able to quantify the variance-based sensitivities associated with individual reaction channels, as well as the importance of channel interactions. Implementation of the algorithms is illustrated in light of simulations of simplified systems, including the birth-death, Schlögl, and Michaelis-Menten models.

  4. Ammonia effect on hydrogenotrophic methanogens and syntrophic acetate oxidizing bacteria

    DEFF Research Database (Denmark)

    Wang, Han; Fotidis, Ioannis; Angelidaki, Irini

    2015-01-01

    Ammonia-rich substrates can cause inhibition on anaerobic digestion process. Syntrophic acetate oxidizing bacteria (SAOB) and hydrogenotrophic methanogens are important for the ammonia inhibitory mechanism on anaerobic digestion. The roles and interactions of SAOB and hydrogenotrophic methanogens...

  5. Thermal decomposition of allylbenzene ozonide

    Energy Technology Data Exchange (ETDEWEB)

    Ewing, J.C.; Church, D.F.; Pryor, W.A. (Louisiana State Univ., Baton Rouge (USA))

    1989-07-19

    Thermal decomposition of allylbenzene ozonide (ABO) at 98{degree}C in the liquid phase yields toluene, bibenzyl, phenylacetaldehyde, formic acid, and (benzyloxy)methyl formate as major products; benzyl chloride is formed when chlorinated solvents are employed. These products, as well as benzyl formate, are formed when ABO is decomposed at 37{degree}C. When the decomposition of ABO is carried out in the presence of 1-butanethiol, the product distribution changes: yields of toluene increase, no bibenzyl is formed, and decreases in yields of (benzyloxy)methyl formate, phenylacetladehyde, and benzyl chloride are observed. The decomposition of 1-octene ozonide (OTO) also was studied for comparison. The activation parameters for both ABO and OTO are similar (28.2 kcal/mol, log A = 13.6 and 26.6 kcal/mol, log A = 12.5, respectively); these data suggest that ozonides decompose by homolysis of the O-O bond, rather than by an alternative synchronous two-bond scission process. When ABO is decomposed at 37{degree}C in the presence of the spin traps 5,5-dimethyl-1-pyrroline N-oxide (DMPO) or 3,3,5,5-tetramethyl-1-pyrroline N-oxide (M{sub 4}PO), ESR signals are observed that are consistent with the trapping of benzyl and other carbon- and oxygen-centered radicals. A mechanism for the thermal decomposition of ABO that involves peroxide bond homolysis and subsequent {beta}-scission is proposed. Thus, Criegee ozonides decompose to give free radicals at quite modest temperatures.

  6. Thermal decomposition of natural dolomite

    Indian Academy of Sciences (India)

    S Gunasekaran; G Anbalagan

    2007-08-01

    Thermal decomposition behaviour of dolomite sample has been studied by thermogravimetric (TG) measurements. Differential thermal analysis (DTA) curve of dolomite shows two peaks at 777.8°C and 834°C. The two endothermic peaks observed in dolomite are essentially due to decarbonation of dolomite and calcite, respectively. The TG data of the decomposition steps have also been analysed using various differential, difference-differential and integral methods, viz. Freeman–Carroll, Horowitz–Metzger, Coats–Redfern methods. Values of activation entropy, Arrhenius factor, and order of reaction have been approximated and compared. Measured activation energies vary between 97 and 147 kJ mol-1. The large fluctuation in activation energy is attributed to the presence of impurities such as SiO2, Al2O3, Fe2O3, Cl- etc in the samples. FTIR and XRD analyses confirm the decomposition reaction. SEM observation of the heat-treated samples at 950°C shows cluster of grains, indicating the structural transformation.

  7. A Lagrangian Dynamic Mode Decomposition

    CERN Document Server

    Sesterhenn, Jörn

    2016-01-01

    Temporal or spatial structures are readily extracted from complex data by modal decompositions like POD or DMD. Subspaces of that decompositions serve as reduced order models and define spatial structures in time or temporal structures in space. Convecting phenomena pose a major problem to those decompositions. A structure travelling with a certain group velocity will be perceived as a plethora of modes in time or space respectively. This manifests itself for example in poorly decaying Singular Values when using a POD. The poor decay is very counter-intuitive, since we expect a single structure to be represented by a few modes. The intuition proves to be correct and we show that in a properly chosen reference frame along the characteristic defined by the group velocity, a POD or DMD reduces moving structures to a few modes, as expected. Beyond serving as a reduced model, the re- sulting entity can be used to define a constant or minimally changing structure in turbulent flows. This can be interpreted as an em...

  8. Diffusion of ammonia gas in PDMS characterized by ATR spectroscopy

    Science.gov (United States)

    Levinský, Petr; Kalvoda, Ladislav; Aubrecht, Jan; Fojtíková, Jaroslava

    2015-01-01

    The kinetic parameters of a chemo-optical transducer layer sensitive to gaseous ammonia are characterized by means of attenuation total reflection method. The tested layer consists of cross-linked polydimethylsiloxane matrix sensitized by quinoline-based organometallic dye showing the selective chemical reaction with ammonia. Upper and lower limits of the ammonia diffusion coefficient and the ammonia-dye reaction constant are derived from the obtained experimental data and compared with other data available in literature and obtained from computer simulations.

  9. Ammonia production, excretion, toxicity, and defense in fish: A Review

    Directory of Open Access Journals (Sweden)

    Alex Y K Ip

    2010-10-01

    Full Text Available Many fishes are ammonotelic but some species can detoxify ammonia to glutamine or urea. Certain fish species can accumulate high levels of ammonia in the brain or defense against ammonia toxicity by enhancing the effectiveness of ammonia excretion through active NH4+ transport, manipulation of ambient pH, or reduction in ammonia permeability through the branchial and cutaneous epithelia. Recent reports on ammonia toxicity in mammalian brain reveal the importance of permeation of ammonia through the blood-brain barrier and passages of ammonia and water through transporters in the plasmalemma of brain cells. Additionally, brain ammonia toxicity could be related to the passage of glutamine through the mitochondrial membranes into the mitochondrial matrix. On the other hand, recent reports on ammonia excretion in fish confirm the involvement of Rhesus glycoproteins in the branchial and cutaneous epithelia. Therefore, this review focuses on both the earlier literature and the up-to-date information on the problems and mechanisms concerning the permeation of ammonia, as NH3, NH4+ or proton-neutral nitrogenous compounds, across mitochondrial membranes, the blood-brain barrier, the plasmalemma of neurons, and the branchial and cutaneous epithelia of fish. It also addresses how certain fishes with high ammonia tolerance defend against ammonia toxicity through the regulation of the permeation of ammonia and related nitrogenous compounds through various types of membranes. It is hoped that this review would revive the interests in investigations on the passage of ammonia through the mitochondrial membranes and the blood-brain barrier of ammonotelic fishes and fishes with high brain ammonia-tolerance, respectively.

  10. Modelling of ammonia emissions from dairy cow houses

    OpenAIRE

    Monteny, G.J.

    2000-01-01

    Dairy cow husbandry contributes to environmental acidification through the emission of ammonia. In-depth knowledge on the processes and variable factors that play a role in the emission of ammonia from dairy cow houses benefits the production of emission data, the development of low emission housing systems, and evaluation of emission levels in a farming system approach. A mechanistic simulation model for the ammonia emission from dairy cow houses was developed to facilitate this.An ammonia p...

  11. Detection of Ammonia in Liquids Using Millimeter Wave Spectroscopy

    Directory of Open Access Journals (Sweden)

    Hilmi Ozturk

    2012-01-01

    Full Text Available Detection of ammonia plays a vital role for counter-bioterrorism applications. Using millimeter wave absorption measurements, ammonia dissolved in water solution is analyzed and compared to water-only solution. The inversion of ammonia molecule results in split rotational spectral lines and transitions of these lines can be detected. Two-port measurements were carried out with vector network analyzer and measurements revealed that ammonia presence can be identified, especially between 30–35 GHz.

  12. HYDROGEN TRANSFER IN CATALYTIC CRACKING

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

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

  13. Catalytic hydrolysis of CFC-12 over solid acid Ti(SO4)2

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    The catalytic hydrolysis of dichlorodifluoromethane (CFC-12) was investigated over solid acid Ti(SO4)2. The catalytic activity decreased with the calcination temperature. When space velocity was 6 l h-1 g-cat-1, the CFC-12 conversion at 310oC over Ti(SO4)2 calcined at 350oC remained about 98.5% during 360 h on stream, and the selectivity to by-products remained zero. The findings enlarged the scope of traditional catalyst systems for the CFCs decomposition.

  14. Bifunctional catalytic electrode

    Science.gov (United States)

    Cisar, Alan (Inventor); Murphy, Oliver J. (Inventor); Clarke, Eric (Inventor)

    2005-01-01

    The present invention relates to an oxygen electrode for a unitized regenerative hydrogen-oxygen fuel cell and the unitized regenerative fuel cell having the oxygen electrode. The oxygen electrode contains components electrocatalytically active for the evolution of oxygen from water and the reduction of oxygen to water, and has a structure that supports the flow of both water and gases between the catalytically active surface and a flow field or electrode chamber for bulk flow of the fluids. The electrode has an electrocatalyst layer and a diffusion backing layer interspersed with hydrophilic and hydrophobic regions. The diffusion backing layer consists of a metal core having gas diffusion structures bonded to the metal core.

  15. Catalytic quantum error correction

    CERN Document Server

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

    2006-01-01

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

  16. Nitrite as a stimulus for ammonia-starved Nitrosomonas europaea

    NARCIS (Netherlands)

    Laanbroek, H.J.; Bär-Gilissen, M.J.; Hoogveld, H.L.

    2002-01-01

    Ammonia-starved cells of Nitrosomonas europaea are able to preserve a high level of ammonia-oxidizing activity in the absence of ammonium. However, when the nitrite-oxidizing cells that form part of the natural nitrifying community do not keep pace with the ammonia-oxidizing cells, nitrite accumulat

  17. Werkwijze voor het behandelen van ammonia-houdend afvalwater

    NARCIS (Netherlands)

    Loosdrecht, M.C.M.; Jetten, M.S.M.

    1998-01-01

    Treatment of ammonia-comprising waste water comprises: (a) subjecting the waste water to a nitrification treatment using a nitrifying microorganism and adding oxygen, to give a solution comprising an oxidation product of ammonia, and (b) converting the oxidation product of ammonia into nitrogen usin

  18. Innovative bioelectrochemical-anaerobic-digestion integrated system for ammonia recovery and bioenergy production from ammonia-rich residues

    DEFF Research Database (Denmark)

    Zhang, Yifeng; Angelidaki, Irini

    2015-01-01

    (SMRC) and a continuous stirred tank reactor (CSTR), to prevent ammonia toxicity during anaerobic digestion by in-situ ammonia recovery and electricity production (Figure 1). In batch experiment, the ammonia concentration in the CSTR decreased from 6 to 0.7 g-N/L with an average recovery rate of 0.18 g-N/L(CSTR...... performance was enhanced. In addition, the coexistence of other cations in CSTR or cathode had no negative effect on the ammonia transportation. In continuous reactor operation, 112% extra biogas production was achieved due to ammonia recovery. High-throughput molecular sequencing analysis showed an impact...... of ammonia recovery on the microbial community composition in the integrated system. Results clearly indicate the great potential of the SMRC-CSTR-coupled system for efficient and cost-effective ammonia recovery, energy production and treatment of ammonia-rich residues....

  19. Catalytic Combustion of Gasified Waste

    Energy Technology Data Exchange (ETDEWEB)

    Kusar, Henrik

    2003-09-01

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

  20. Ammonia tolerant enriched methanogenic cultures as bioaugmentation inocula to alleviate ammonia inhibition in continuous anaerobic reactors

    DEFF Research Database (Denmark)

    Fotidis, Ioannis; Wang, Han; Angelidaki, Irini

    tolerant methanogenic culture as potential bioaugmentation inoculum in a continuous stirred tank reactor (CSTR) operating under “inhibited steady-state”, triggered by high ammonia levels (5 g NH4+-N L-1). The results of the current study established for the first time that bioaugmentation of an enriched...... ammonia tolerant methanogen in a CSTR reactor could completely alleviate the ammonia inhibitory effect. Furthermore, it was found that bioaugmentation with the enriched culture resulted in 25% higher methane production compared to when the bioaugmentation was achieved with pure methanogenic strains....... The bioaugmentation was performed without pausing the continuous operation of the CSTR reactor and without excluding the ammonia-rich substrate from the feedstock. Thus, bioaugmentation with mixed methanogenic cultures could potentially support the development of an efficient and cost-effective biomethanation process...

  1. Treatment of nickel-ammonia complex ion-containing ammonia nitrogen wastewater

    Institute of Scientific and Technical Information of China (English)

    MIN Xiao-bo; ZHOU Min; CHAI Li-yuan; WANG Yun-yan; SHU Yu-de

    2009-01-01

    Air stripping was adopted to treat nickel ammonia complex ion-containing wastewater in order to remove nickel and ammonia simultaneously in one technological process. The relationship among pH, the concentration of nickel ammonia complex ion and total ammonia concentration was analyzed theoretically. Influence of pH value, water temperature, airflow rate and time on air stripping was studied in detail by static experiment in laboratory. The results show that at pH 11, temperature of 60 ℃ and airflow rate of 0.12 m~3/h, NH_3 and Ni~(2+) concentrations remained in wastewater are less than 2 and 0.2 mg/L, respectively, after blowing for 75 min, which reaches the standard of the state discharge. When the tail gas is absorbed by 0.5 mol/L H_2SO_4 in order to avoid the secondary pollution, the absorption rate can achieve 70%.

  2. USDA-EPA Collaborative Ammonia Research

    Science.gov (United States)

    In 2014, a work group was formed between USDA and EPA to facilitate information exchange on ammonia emissions from agriculture, air quality impacts and emission mitigation options and to identify opportunities for collaboration. This document provides background on the work grou...

  3. Adsorption of Ammonia on Regenerable Carbon Sorbents

    Science.gov (United States)

    Wójtowicz, Marek A.; Cosgrove, Jesph E.; Serio, Michael A..; Wilburn, Monique

    2015-01-01

    Results are presented on the development of reversible sorbents for the combined carbon dioxide, moisture, and trace-contaminant (TC) removal for use in Extravehicular Activities (EVAs), and more specifically in the Primary Life Support System (PLSS). The currently available life support systems use separate units for carbon dioxide, trace contaminants, and moisture control, and the long-term objective is to replace the above three modules with a single one. Data on sorption and desorption of ammonia, which is a major TC of concern, are presented in this paper. The current TC-control technology involves the use of a packed bed of acid-impregnated granular charcoal, which is non-regenerable, and the carbon-based sorbent under development in this project can be regenerated by exposure to vacuum at room temperature. In this study, several carbon sorbents were fabricated and tested for ammonia sorption. Ammonia-sorption capacity was related to carbon pore structure characteristics, and the temperature of oxidative carbon-surface treatment was optimized for enhanced ammonia-sorption performance.

  4. Footprints on Ammonia Concentrations from Environmental Regulations

    DEFF Research Database (Denmark)

    Skjøth, Carsten Ambelas; Ellermann, Thomas; Hertel, Ole;

    2008-01-01

    Releases of ammonia (NH3) to the atmosphere contribute significantly to the desposition of nitrogen to both terrestrial and aquatic ecosystems. This is the background for the national NH3 emission ceilings in Europe. However, in some countries the national legislation aims not only to meet theese...

  5. Ammonia in comet P/Halley

    Science.gov (United States)

    Meier, R.; Eberhardt, P.; Krankowsky, D.; Hodges, R. R.

    1994-01-01

    In comet P/Halley the abundances of ammonia relative to water reported in the literature differ by about one order of magnitude from roughly 0.1% up to 2%. Different observational techniques seem to have inherent systematic errors. Using the ion mass channels m/q = 19 amu/e, 18 amu/e and 17 amu/e of the Neutral Mass Spectrometer experiment aboard the spacecraft Giotto, we derive a production rate of ammonia of (1.5(sub -0.7)(sup +0.5))% relative to water. Inside the contact surface we can explain our data by a nuclear source only. The uncertainty in our abundance of ammonia is primarily a result of uncertainties in some key reaction coefficients. We discuss in detail these reactions and the range of error indicated results from extreme assumptions in the rate coefficients. From our data, even in the worst case, we can exclude the ammonia abundance to be only of the order of a few per mill.

  6. A porous SiC ammonia sensor

    NARCIS (Netherlands)

    Connolly, E.J.; Timmer, B.H.; Pham, H.T.M.; Groeneweg, J.; Sarro, P.M.; Olthuis, W.; French, P.J.

    2005-01-01

    When used as the dielectric in a capacitive sensing arrangement, porous SiC has been found to be extremely sensitive to the presence of ammonia (NH3) gas. The exact sensing method is still not clear, but NH3 levels as low as 0.5 ppm could be detected. We report the fabrication and preliminary charac

  7. Fiber Optic Detection of Ammonia Gas

    Directory of Open Access Journals (Sweden)

    L. Kalvoda

    2006-01-01

    Full Text Available Bathochromic shifts accompanying the formation of several bivalent metallic complexes containing 5-(4’-dimethylaminophenylimino quinolin-8-one (L1, and 7-chlore-5(4’-diethylamino-2-methylphenylimino quinolin-8-one (L2 ligands in ethanol solutions were evaluated by VIS-NIR spectroscopy. The [L1-Cu-L1] sulphide complex was selected as a reagent for further tests on optical fibres. Samples of multimode siloxane-clad fused-silica fibre were sensitized by diffusing an ethanol/chloroform solution of the dye into the cladding polymer, and tested by VIS-NIR optical spectroscopy (12 cm long fibre sections, and optical time domain reflectometry (OTDR; 20 ns laser pulses, wavelength 850 nm, 120 m long fibre sensitized within the interval 104–110 m. A well-resolved absorption band of the reagent could be identified in the absorption spectra of the fibres. After exposure to dry ammonia/nitrogen gas with increasing ammonia concentration (0–4000 ppm, the short fibre samples showed subsequent decay of NIR optical absorption; saturation was observed for higher ammonia levels. The concentration resolution r ? 50 ppm and forward response time t90 ? 30 sec were obtained within the interval 0–1000 ppm. The OTDR courses showed an enhancement of the back-scattered light intensity coming from the sensitized region after diffusion of the initial reagent, and decay after exposure to concentrated ammonia/nitrogen gas (10000 ppm.

  8. Regulation of the intersubunit ammonia tunnel in Mycobacterium tuberculosis glutamine-dependent NAD[superscript +] synthetase

    Energy Technology Data Exchange (ETDEWEB)

    Chuenchor, Watchalee; Doukov, Tzanko I.; Resto, Melissa; Chang, Andrew; Gerratana, Barbara (SSRL); (Maryland)

    2012-08-31

    Glutamine-dependent NAD{sup +} synthetase is an essential enzyme and a validated drug target in Mycobacterium tuberculosis (mtuNadE). It catalyses the ATP-dependent formation of NAD{sup +} from NaAD{sup +} (nicotinic acid-adenine dinucleotide) at the synthetase active site and glutamine hydrolysis at the glutaminase active site. An ammonia tunnel 40 {angstrom} (1 {angstrom} = 0.1 nm) long allows transfer of ammonia from one active site to the other. The enzyme displays stringent kinetic synergism; however, its regulatory mechanism is unclear. In the present paper, we report the structures of the inactive glutaminase C176A variant in an apo form and in three synthetase-ligand complexes with substrates (NaAD{sup +}/ATP), substrate analogue {l_brace}NaAD{sup +}/AMP-CPP (adenosine 5'-[{alpha},{beta}-methylene]triphosphate){r_brace} and intermediate analogues (NaAD{sup +}/AMP/PPi), as well as the structure of wild-type mtuNadE in a product complex (NAD{sup +}/AMP/PPi/glutamate). This series of structures provides snapshots of the ammonia tunnel during the catalytic cycle supported also by kinetics and mutagenesis studies. Three major constriction sites are observed in the tunnel: (i) at the entrance near the glutaminase active site; (ii) in the middle of the tunnel; and (iii) at the end near the synthetase active site. Variation in the number and radius of the tunnel constrictions is apparent in the crystal structures and is related to ligand binding at the synthetase domain. These results provide new insight into the regulation of ammonia transport in the intermolecular tunnel of mtuNadE.

  9. Thermic decomposition of biphenyl; Decomposition thermique du biphenyle

    Energy Technology Data Exchange (ETDEWEB)

    Lutz, M. [Commissariat a l' Energie Atomique, Saclay (France). Centre d' Etudes Nucleaires

    1966-03-01

    Liquid and vapour phase pyrolysis of very pure biphenyl obtained by methods described in the text was carried out at 400 C in sealed ampoules, the fraction transformed being always less than 0.1 per cent. The main products were hydrogen, benzene, terphenyls, and a deposit of polyphenyls strongly adhering to the walls. Small quantities of the lower aliphatic hydrocarbons were also found. The variation of the yields of these products with a) the pyrolysis time, b) the state (gas or liquid) of the biphenyl, and c) the pressure of the vapour was measured. Varying the area and nature of the walls showed that in the absence of a liquid phase, the pyrolytic decomposition takes place in the adsorbed layer, and that metallic walls promote the reaction more actively than do those of glass (pyrex or silica). A mechanism is proposed to explain the results pertaining to this decomposition in the adsorbed phase. The adsorption seems to obey a Langmuir isotherm, and the chemical act which determines the overall rate of decomposition is unimolecular. (author) [French] Du biphenyle tres pur, dont la purification est decrite, est pyrolyse a 400 C en phase vapeur et en phase liquide dans des ampoules scellees sous vide, a des taux de decomposition n'ayant jamais depasse 0,1 pour cent. Les produits provenant de la pyrolyse sont essentiellement: l' hydrogene, le benzene, les therphenyles, et un depot de polyphenyles adherant fortement aux parois. En plus il se forme de faibles quantites d'hydrocarbures aliphatiques gazeux. On indique la variation des rendements des differents produits avec la duree de pyrolyse, l'etat gazeux ou liquide du biphenyle, et la pression de la vapeur. Variant la superficie et la nature des parois, on montre qu'en absence de liquide la pyrolyse se fait en phase adsorbee. La pyrolyse est plus active au contact de parois metalliques que de celles de verres (pyrex ou silice). A partir des resultats experimentaux un mecanisme de

  10. High performance vanadia-anatase nanoparticle catalysts for the selective catalytic reduction of NO by ammonia

    DEFF Research Database (Denmark)

    Kristensen, Steffen Buus; Kunov-Kruse, Andreas Jonas; Riisager, Anders;

    2011-01-01

    Highly active nanoparticle SCR deNO(x) catalysts composed of amorphous vanadia on crystalline anatase have been prepared by a sol-gel, co-precipitation method using decomposable crystallization seeds. The catalysts were characterized by means of XRPD, TEM/SEM, FT-IR, nitrogen physisorption and NH(3......) catalysts reported in the literature in the examined temperature range of 200-400 degrees C. The catalysts showed very high resistivity towards potassium poisoning maintaining a 15-30 times higher activity than the equally poisoned industrial reference catalyst, upon impregnation by 280 mu mole potassium...

  11. Heteropoly acid promoted Cu and Fe catalysts for the selective catalytic reduction of NO with ammonia

    DEFF Research Database (Denmark)

    Putluru, Siva Sankar Reddy; Mossin, Susanne L.; Riisager, Anders;

    2011-01-01

    Cu/TiO2, Fe/TiO2 and heteropoly acid promoted Cu/TiO2, Fe/TiO2 catalysts were prepared and characterized by N2 physisorption, XRPD, NH3-TPD, H2-TPR and EPR. The catalysts exhibited only crystalline TiO2 phases with the active metals and promoters in highly dispersed state. The acidic properties...

  12. Electronic factors in catalysis: the volcano curve and the effect of promotion in catalytic ammonia synthesis

    DEFF Research Database (Denmark)

    Dahl, Søren; Logadottir, Ashildur; Jacobsen, C.J.H.;

    2001-01-01

    industrial conditions can be determined as a function of the nitrogen-surface interaction energy by combining the calculated adsorption energy-activation energy relation with a micro-kinetic model. The result is a volcano curve and we illustrate such relationships for both the non-promoted and alkali metal...

  13. Ceria-supported ruthenium nanoparticles as highly active and long-lived catalysts in hydrogen generation from the hydrolysis of ammonia borane.

    Science.gov (United States)

    Akbayrak, Serdar; Tonbul, Yalçın; Özkar, Saim

    2016-07-01

    Ruthenium(0) nanoparticles supported on ceria (Ru(0)/CeO2) were in situ generated from the reduction of ruthenium(iii) ions impregnated on ceria during the hydrolysis of ammonia borane. Ru(0)/CeO2 was isolated from the reaction solution by centrifugation and characterized by ICP-OES, BET, XRD, TEM, SEM-EDS and XPS techniques. All the results reveal that ruthenium(0) nanoparticles were successfully supported on ceria and the resulting Ru(0)/CeO2 is a highly active, reusable and long-lived catalyst for hydrogen generation from the hydrolysis of ammonia borane with a turnover frequency value of 361 min(-1). The reusability tests reveal that Ru(0)/CeO2 is still active in the subsequent runs of hydrolysis of ammonia borane preserving 60% of the initial catalytic activity even after the fifth run. Ru(0)/CeO2 provides a superior catalytic lifetime (TTO = 135 100) in hydrogen generation from the hydrolysis of ammonia borane at 25.0 ± 0.1 °C before deactivation. The work reported here includes the formation kinetics of ruthenium(0) nanoparticles. The rate constants for the slow nucleation and autocatalytic surface growth of ruthenium(0) nanoparticles were obtained using hydrogen evolution as a reporter reaction. An evaluation of rate constants at various temperatures enabled the estimation of activation energies for both the reactions, Ea = 60 ± 7 kJ mol(-1) for the nucleation and Ea = 47 ± 2 kJ mol(-1) for the autocatalytic surface growth of ruthenium(0) nanoparticles, as well as the activation energy of Ea = 51 ± 2 kJ mol(-1) for the catalytic hydrolysis of ammonia borane. PMID:27302302

  14. Thermal and catalytic cracking of ethylene in presence of CaO, MgO, zeolite and calcined dolomite

    Energy Technology Data Exchange (ETDEWEB)

    Taralas, G.; Sjoestroem, K.; Jaeraas, S.; Bjoernbom, E. [Royal Inst. of Tech., Stockholm (Sweden). Dept. of Chemical Technology

    1993-12-31

    The subject of the present work is to study the effect of catalysts such as calcined dolomite (CaO.MgO), CaO (quicklime), MgO and Zeolite (EKZ-4) on the cracking of ethylene in the presence and absence of steam. N-heptane, toluene, naphthalene, thiophene have been some suitable model compounds for studies of the thermal and catalytic decomposition of tar. Previous results showed that the reaction scheme of the thermal decomposition of n-heptane was consistent with the high yield of ethylene observed in thermal decomposition of n-heptane. The effect of the reactor wall and the ferric impurities in the dolomite are also subjects of the research in this study. The results may also throw some additional light on the nature of the gas-phase thermal and catalytic reactions occurring in the use of dolomite as tar cracking catalysts. 28 refs

  15. Colorimetric polymer-metal nanocomposite sensor of ammonia for the agricultural industry of confined animal feeding operations

    Science.gov (United States)

    Sarkisov, Sergey S.; Czarick, Michael; Fairchild, Brian D.; Liang, Yi; Kukhtareva, Tatiana; Curley, Michael J.

    2014-02-01

    The proposed colorimetric sensor of ammonia for the confined animal feeding industry uses the method of optoelectronic spectroscopic measurement of the reversible change of the color of a nanocomposite reagent film in response to ammonia. The film is made of a gold nanocolloid in a polymer matrix with an ammonia-sensitive indicator dye additive. The response of the indicator dye (increase of the optical absorption between 550 and 650 nm) is enhanced by the nanoparticles (˜8 nm in size) in two ways: (a) concentration of the optical field near the nanoparticle due to the plasmon resonance and (b) catalytic acceleration of the chemical reaction of deprotonization of the indicator dye in the presence of ammonia and water vapor. This enhancement helps to miniaturize the sensing element without compromising its sensitivity of <1 parts per million (ppm) for the range 0 to 100 ppm. The sensor underwent field tests in commercial poultry farms in Georgia and Arkansas and was compared against a scientific-grade photoacoustic gas analyzer. The coefficient of correlation between the sensor and the photoacoustic data for several weeks of continuous side-by-side operation in a commercial poultry house was ˜0.9 and the linear regression slope was 1.0. The conclusions on the necessary improvements were made.

  16. Effect of Activated Carbon as a Support on Metal Dispersion and Activity of Ruthenium Catalyst for Ammonia Synthesis

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    Ten kinds of activated carbon from different raw materials were used as supports to prepare ruthenium catalysts. N2 physisorption and CO chemisorption were carried out to investigate the pore size distribution and the ruthenium dispersion of the catalysts. It was found that the Ru dispersion of the catalyst was closely related to not only the texture of carbon support but also the purity of activated carbon. The activities of a series of the carbon-supported barium-promoted Ru catalysts for ammonia synthesis were measured at 425 ℃, 10.0 MPa and 10 000 h-1. The result shows that the same raw material activated carbon, with a high purity, high surface area, large pore volume and reasonable pore size distribution might disperse ruthenium and promoter sufficiently, which activated carbon as support, could be used to manufacture ruthenium catalyst with a high activity for ammonia synthesis. The different raw material activated carbon as the support would greatly influence the catalytic properties of the ruthenium catalyst for ammonia synthesis. For example, with coconut shell carbon(AC1) as the support, the ammonia concentration in the effluent was 13.17% over 4%Ru-BaO/AC1 catalyst, while with the desulfurized coal carbon(AC10) as the support, that in the effluent was only 1.37% over 4%Ru-BaO/AC10 catalyst.

  17. Ammonia downstream from HH 80 North

    Science.gov (United States)

    Girart, Jose M.; Rodriguez, Luis F.; Anglada, Guillem; Estalella, Robert; Torrelles, Jose, M.; Marti, Josep; Pena, Miriam; Ayala, Sandra; Curiel, Salvador; Noriega-Crespo, Alberto

    1994-01-01

    HH 80-81 are two optically visible Herbig-Haro (HH) objects located about 5 minutes south of their exciting source IRAS 18162-2048. Displaced symmetrically to the north of this luminous IRAS source, a possible HH counterpart was recently detected as a radio continuum source with the very large array (VLA). This radio source, HH 80 North, has been proposed to be a member of the Herbig-Haro class since its centimeter flux density, angular size, spectral index, and morphology are all similar to those of HH 80. However, no object has been detected at optical wavelengths at the position of HH 80 North, possibly because of high extinction, and the confirmation of the radio continuum source as an HH object has not been possible. In the prototypical Herbig-Haro objects HH 1 and 2, ammonia emission has been detected downstream of the flow in both objects. This detection has been intepreted as a result of an enhancement in the ammonia emission produced by the radiation field of the shock associated with the HH object. In this Letter we report the detection of the (1,1) and (2,2) inversion transitions of ammonia downstream HH 80 North. This detection gives strong suppport to the interpretation of HH 80 North as a heavily obscured HH object. In addition, we suggest that ammonia emission may be a tracer of embedded Herbig-Haro objects in other regions of star formation. A 60 micrometer IRAS source could be associated with HH 80 North and with the ammonia condensation. A tentative explanation for the far-infrared emission as arising in dust heated by their optical and UV radiation of the HH object is presented.

  18. Ammonia and ammonium hydroxide sensors for ammonia/water absorption machines: Literature review and data compilation

    Energy Technology Data Exchange (ETDEWEB)

    Anheier, N.C. Jr.; McDonald, C.E.; Cuta, J.M.; Cuta, F.M.; Olsen, K.B.

    1995-05-01

    This report describes an evaluation of various sensing techniques for determining the ammonia concentration in the working fluid of ammonia/water absorption cycle systems. The purpose of this work was to determine if any existing sensor technology or instrumentation could provide an accurate, reliable, and cost-effective continuous measure of ammonia concentration in water. The resulting information will be used for design optimization and cycle control in an ammonia-absorption heat pump. PNL researchers evaluated each sensing technology against a set of general requirements characterizing the potential operating conditions within the absorption cycle. The criteria included the physical constraints for in situ operation, sensor characteristics, and sensor application. PNL performed an extensive literature search, which uncovered several promising sensing technologies that might be applicable to this problem. Sixty-two references were investigated, and 33 commercial vendors were identified as having ammonia sensors. The technologies for ammonia sensing are acoustic wave, refractive index, electrode, thermal, ion-selective field-effect transistor (ISFET), electrical conductivity, pH/colormetric, and optical absorption. Based on information acquired in the literature search, PNL recommends that follow-on activities focus on ISFET devices and a fiber optic evanescent sensor with a colormetric indicator. The ISFET and fiber optic evanescent sensor are inherently microminiature and capable of in situ measurements. Further, both techniques have been demonstrated selective to the ammonium ion (NH{sub 4}{sup +}). The primary issue remaining is how to make the sensors sufficiently corrosion-resistant to be useful in practice.

  19. Ammonia and ammonium hydroxide sensors for ammonia/water absorption machines: Literature review and data compilation

    Science.gov (United States)

    Anheier, N. C., Jr.; McDonald, C. E.; Cuta, J. M.; Cuta, F. M.; Olsen, K. B.

    1995-05-01

    This report describes an evaluation of various sensing techniques for determining the ammonia concentration in the working fluid of ammonia/water absorption cycle systems. The purpose was to determine if any existing sensor technology or instrumentation could provide an accurate, reliable, and cost-effective continuous measure of ammonia concentration in water. The resulting information will be used for design optimization and cycle control in an ammonia-absorption heat pump. Pacific Northwest Laboratory (PNL) researchers evaluated each sensing technology against a set of general requirements characterizing the potential operating conditions within the absorption cycle. The criteria included the physical constraints for in situ operation, sensor characteristics, and sensor application. PNL performed an extensive literature search, which uncovered several promising sensing technologies that might be applicable to this problem. Sixty-two references were investigated, and 33 commercial vendors were identified as having ammonia sensors. The technologies for ammonia sensing are acoustic wave, refractive index, electrode, thermal, ion-selective field-effect transistor (ISFET), electrical conductivity, pH/colormetric, and optical absorption. Based on information acquired in the literature search, PNL recommends that follow-on activities focus on ISFET devices and a fiber optic evanescent sensor with a colormetric indicator. The ISFET and fiber optic evanescent sensor are inherently microminiature and capable of in situ measurements. Further, both techniques have been demonstrated selective to the ammonium ion (NH4(+)). The primary issue remaining is how to make the sensors sufficiently corrosion-resistant to be useful in practice.

  20. Ammonia regeneration for a combined lime/ammonia spray dryer for SO[sub 2] control

    Energy Technology Data Exchange (ETDEWEB)

    Xinjian, Yang (Cincinnati Univ., OH (United States). Dept. of Civil and Environmental Engineering)

    1992-12-23

    A research project designed to study the feasibility of ammonia regeneration for a combined lime/ammonia FGD process was conducted at the University of Cincinnati. The major objective for this project was to regenerate ammonia from a combined ammonia/calcium hydroxide spray dryer FGD byproduct for reuse which would reduce the operating cost of this FGD process. This final report covers the six phases of the project: (1) generation of original feedstock, (2) batch regeneration studies, (3) continuous regeneration studies, (4) waste characteristic analysis, (5) pilot scale demonstration and (6) economic analysis. This research has shown that regeneration of ammonia is feasible at a reasonable cost. The effects on Ohio coal use from the results of this research could be substantial, depending on the Phase II application of FGD systems for controlling SO[sub 2] emissions. In conclusion, experiments in this study have shown that ammonia recovery efficiencies greater than 90% are technically and economically feasible. In addition, the sludge produced from the regeneration process is stable and will meet existing Federal standards.

  1. The effect of a detonation nanodiamond coating on the thermal decomposition properties of RDX explosives.

    Science.gov (United States)

    Tong, Yi; Liu, Rui; Zhang, Tonglai

    2014-09-01

    A well-dispersed and uniformly shaped detonation nanodiamond (DND) was produced and coated over micron scale RDX in various amounts to form four kinds of DND coating composites (NDRs). In order to confirm the optimal coating amount and its effect on the thermal properties, the thermal decomposition and kinetics were studied by DSC, TG and DPTA techniques. The critical temperature of thermal explosion (Tb) and the self accelerating decomposition temperature (T(SADT)) both exhibit an interesting volcano-shaped changing trend and rank in an increasing order of NDR4 gas emission and reaction rate constant of the initial thermal decomposition have the same order. The results show that the DND coating could improve the reactivity of the NDRs and the effect is proportional to the coating amount. However, excessive coating that is more than 1/3 conversely hinders decomposition and gas diffusion, like a layer of protective shell. The isoconversional activation energy (Ea) varies with the conversion extent (α) at the initial stage of α = 0.1-0.5, which indicates that the thermal decomposition of the NDRs is a multi-step process including the secondary reaction or catalytic reaction. However, the Ea values are almost independent of α when α = 0.6-0.9, with the mean values in an increasing order of NDR1 < NDR4 < NDR2 < NDR3. PMID:25027243

  2. Decomposition of toluene in a steady-state atmospheric-pressure glow discharge

    Science.gov (United States)

    Trushkin, A. N.; Grushin, M. E.; Kochetov, I. V.; Trushkin, N. I.; Akishev, Yu. S.

    2013-02-01

    Results are presented from experimental studies of decomposition of toluene (C6H5CH3) in a polluted air flow by means of a steady-state atmospheric pressure glow discharge at different water vapor contents in the working gas. The experimental results on the degree of C6H5CH3 removal are compared with the results of computer simulations conducted in the framework of the developed kinetic model of plasma chemical decomposition of toluene in the N2: O2: H2O gas mixture. A substantial influence of the gas flow humidity on toluene decomposition in the atmospheric pressure glow discharge is demonstrated. The main mechanisms of the influence of humidity on C6H5CH3 decomposition are determined. The existence of two stages in the process of toluene removal, which differ in their duration and the intensity of plasma chemical decomposition of C6H5CH3 is established. Based on the results of computer simulations, the composition of the products of plasma chemical reactions at the output of the reactor is analyzed as a function of the specific energy deposition and gas flow humidity. The existence of a catalytic cycle in which hydroxyl radical OH acts a catalyst and which substantially accelerates the recombination of oxygen atoms and suppression of ozone generation when the plasma-forming gas contains water vapor is established.

  3. Silver nanowires as catalytic cathodes for stabilizing lithium-oxygen batteries

    Science.gov (United States)

    Kwak, Won-Jin; Jung, Hun-Gi; Lee, Seon-Hwa; Park, Jin-Bum; Aurbach, Doron; Sun, Yang-Kook

    2016-04-01

    Silver nanowires have been investigated as a catalytic cathode material for lithium-oxygen batteries. Their high aspect ratio contributes to the formation of a corn-shaped layer structure of the poorly crystalline lithium peroxide (Li2O2) nanoparticles produced by oxygen reduction in poly-ether based electrolyte solutions. The nanowire morphology seems to provide the necessary large contact area and facile electron supply for a very effective oxygen reduction reaction. The unique morphology and structure of the Li2O2 deposits and the catalytic nature of the silver nano-wires promote decomposition of Li2O2 at low potentials (below 3.4 V) upon the oxygen evolution. This situation avoids decomposition of the solution species and oxidation of the electrodes during the anodic (charge) reactions, leading to high electrical efficiently of lithium-oxygen batteries.

  4. Cerebral ammonia uptake and accumulation during prolonged exercise in humans

    DEFF Research Database (Denmark)

    Nybo, Lars; Dalsgaard, Mads K.; Steensberg, Adam;

    2005-01-01

    We evaluated whether peripheral ammonia production during prolonged exercise enhances the uptake and subsequent accumulation of ammonia within the brain. Two studies determined the cerebral uptake of ammonia (arterial and jugular venous blood sampling combined with Kety-Schmidt-determined cerebral...... blood flow; n = 5) and the ammonia concentration in the cerebrospinal fluid (CSF; n = 8) at rest and immediately following prolonged exercise either with or without glucose supplementation. There was a net balance of ammonia across the brain at rest and at 30 min of exercise, whereas 3 h of exercise...... exercise with glucose, and further to 16.1 ± 3.3 µM after the placebo trial (P

  5. Catalytic production of biodiesel

    Energy Technology Data Exchange (ETDEWEB)

    Theilgaard Madsen, A.

    2011-07-01

    The focus of this thesis is the catalytic production of diesel from biomass, especially emphasising catalytic conversion of waste vegetable oils and fats. In chapter 1 an introduction to biofuels and a review on different catalytic methods for diesel production from biomass is given. Two of these methods have been used industrially for a number of years already, namely the transesterification (and esterification) of oils and fats with methanol to form fatty acid methyl esters (FAME), and the hydrodeoxygenation (HDO) of fats and oils to form straight-chain alkanes. Other possible routes to diesel include upgrading and deoxygenation of pyrolysis oils or aqueous sludge wastes, condensations and reductions of sugars in aqueous phase (aqueous-phase reforming, APR) for monofunctional hydrocarbons, and gasification of any type of biomass followed by Fischer-Tropsch-synthesis for alkane biofuels. These methods have not yet been industrialised, but may be more promising due to the larger abundance of their potential feedstocks, especially waste feedstocks. Chapter 2 deals with formation of FAME from waste fats and oils. A range of acidic catalysts were tested in a model fat mixture of methanol, lauric acid and trioctanoin. Sulphonic acid-functionalised ionic liquids showed extremely fast convertion of lauric acid to methyl laurate, and trioctanoate was converted to methyl octanoate within 24 h. A catalyst based on a sulphonated carbon-matrix made by pyrolysing (or carbonising) carbohydrates, so-called sulphonated pyrolysed sucrose (SPS), was optimised further. No systematic dependency on pyrolysis and sulphonation conditions could be obtained, however, with respect to esterification activity, but high activity was obtained in the model fat mixture. SPS impregnated on opel-cell Al{sub 2}O{sub 3} and microporous SiO{sub 2} (ISPS) was much less active in the esterification than the original SPS powder due to low loading and thereby low number of strongly acidic sites on the

  6. Syzygy Decompositions and Projective Resolutions

    OpenAIRE

    Smith, Nathan A.

    1999-01-01

    We give a projective resolution of a finite dimensional K-algebra A over its enveloping algebra Ae = Aop à KA. The description of this resolution is related to decompositions of the first syzygy module of A as an Ae module. Resolutions of right A modules MA may be obtained by tensoring M over A with this bimodule resoution. We describe how to obtain such a resolution when M is simple or when M is given in the form of a projective presentation. Computatio...

  7. Catalytic Hydrothermal Gasification

    Energy Technology Data Exchange (ETDEWEB)

    Elliott, Douglas C.

    2015-05-31

    The term “hydrothermal” used here refers to the processing of biomass in water slurries at elevated temperature and pressure to facilitate the chemical conversion of the organic structures in biomass into useful fuels. The process is meant to provide a means for treating wet biomass materials without drying and to access ionic reaction conditions by maintaining a liquid water processing medium. Typical hydrothermal processing conditions are 523-647K of temperature and operating pressures from 4-22 MPa of pressure. The temperature is sufficient to initiate pyrolytic mechanisms in the biopolymers while the pressure is sufficient to maintain a liquid water processing phase. Hydrothermal gasification is accomplished at the upper end of the process temperature range. It can be considered an extension of the hydrothermal liquefaction mechanisms that begin at the lowest hydrothermal conditions with subsequent decomposition of biopolymer fragments formed in liquefaction to smaller molecules and eventually to gas. Typically, hydrothermal gasification requires an active catalyst to accomplish reasonable rates of gas formation from biomass.

  8. Cobalamin Catalytic Centers for Stable Fuels Generation from Carbon Dioxide

    Science.gov (United States)

    Robertson, Wesley D.; Jawdat, Benmaan I.; Ennist, Nathan M.; Warncke, Kurt

    2010-03-01

    Our aim is to design and construct protein-based artificial photosynthetic systems that reduce carbon dioxide (CO2) to stable fuel forms within the robust and adaptable (βα)8 TIM-barrel protein structure. The EutB subunit of the adenosylcobalamin-dependent enzyme, ethanolamine ammonia-lyase, from Salmonella typhimurium, was selected as the protein template. This system was selected because the Co^I forms of the native cobalamin (Cbl) cofactor, and the related cobinamide (Cbi), possess redox properties that are commensurate with reduction of CO2. The kinetics of photo- (excited 5'-deazariboflavin electron donor) and chemical [Ti(III)] reduction, and subsequent reaction, of the Cbl and Cbi with CO2 are measured by time-resolved UV/visible absorption spectroscopy. Products are quantified by NMR spectroscopy. The results address the efficacy of the organocobalt catalytic centers for CO2 reduction to stable fuels, towards protein device integration.

  9. Study of Ammonia Emissions in a Ventilated Pig Pen

    DEFF Research Database (Denmark)

    Rong, Li

    reported in literature, little effort has been made to investigate the accuracy of current Henry’s law constant for modeling ammonia mass transfer process and study ammonia emissions in a full scale pig pen from fluid dynamics by CFD simulations. This will be the main objectives of this study. The ammonia...... the accuracy of Henry’s law constants to determine the ammonia concentration in the air through the air-liquid interface. None of the present Henry’s law constant models provide a respectable agreement between simulated and measured results. A simplified model to determine the ammonia concentration in the air...... through the air-liquid interface is suggested from vapor-liquid equilibrium properties of ammonia water. Furthermore, the effects of airflow and temperature on ammonia mass transfer coefficient are also analyzed under different concentration boundary conditions determined by various Henry’s law constant...

  10. Pretreatment of Biomass by Aqueous Ammonia for Bioethanol Production

    Science.gov (United States)

    Kim, Tae Hyun; Gupta, Rajesh; Lee, Y. Y.

    The methods of pretreatment of lignocellulosic biomass using aqueous ammonia are described. The main effect of ammonia treatment of biomass is delignification without significantly affecting the carbohydrate contents. It is a very effective pretreatment method especially for substrates that have low lignin contents such as agricultural residues and herbaceous feedstock. The ammonia-based pretreatment is well suited for simultaneous saccharification and co-fermentation (SSCF) because the treated biomass retains cellulose as well as hemicellulose. It has been demonstrated that overall ethanol yield above 75% of the theoretical maximum on the basis of total carbohydrate is achievable from corn stover pretreated with aqueous ammonia by way of SSCF. There are two different types of pretreatment methods based on aqueous ammonia: (1) high severity, low contact time process (ammonia recycle percolation; ARP), (2) low severity, high treatment time process (soaking in aqueous ammonia; SAA). Both of these methods are described and discussed for their features and effectiveness.

  11. Effect of dry torrefaction on kinetics of catalytic pyrolysis of sugarcane bagasse

    Science.gov (United States)

    Daniyanto, Sutijan, Deendarlianto, Budiman, Arief

    2015-12-01

    Decreasing world reserve of fossil resources (i.e. petroleum oil, coal and natural gas) encourage discovery of renewable resources as subtitute for fossil resources. Biomass is one of the main natural renewable resources which is promising resource as alternate resources to meet the world's energy needs and raw material to produce chemical platform. Conversion of biomass, as source of energy, fuel and biochemical, is conducted using thermochemical process such as pyrolysis-gasification process. Pyrolysis step is an important step in the mechanism of pyrolysis - gasification of biomass. The objective of this study is to obtain the kinetic reaction of catalytic pyrolysis of dry torrified sugarcane bagasse which used Ca and Mg as catalysts. The model of kinetic reaction is interpreted using model n-order of single reaction equation of biomass. Rate of catalytic pyrolysis reaction depends on the weight of converted biomass into char and volatile matters. Based on TG/DTA analysis, rate of pyrolysis reaction is influenced by the composition of biomass (i.e. hemicellulose, cellulose and lignin) and inorganic component especially alkali and alkaline earth metallic (AAEM). From this study, it has found two equations rate of reaction of catalytic pyrolysis in sugarcane bagasse using catalysts Ca and Mg. First equation is equation of pyrolysis reaction in rapid zone of decomposition and the second equation is slow zone of decomposition. Value of order reaction for rapid decomposition is n > 1 and for slow decomposition is n<1. Constant and order of reactions for catalytic pyrolysis of dry-torrified sugarcane bagasse with presence of Ca tend to higher than that's of presence of Mg.

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

    OpenAIRE

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

    2015-01-01

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

  13. Mössbauer study of nanodimensional nickel ferrite-mechanochemical synthesis and catalytic properties

    OpenAIRE

    Manova, Elina; Estournès, Claude; Paneva, Daniela; Rehspringer, Jean Luc; Tsoncheva, Tanya; Kunev, Boris; Mitov, Ivan

    2005-01-01

    Iron-nickel spinel oxide NiFe2O4 nanoparticles have been prepared by the combination of chemical precipitation and subsequent mechanical milling. For comparison, their analogue obtained by thermal synthesis is also studied. Phase composition and structural properties of iron-nickel oxides are investigated by X-ray diffraction and Mössbauer spectroscopy. Their catalytic behavior in methanol decomposition to CO and methane is tested. An influence of the preparation method on the reduction and c...

  14. Photocatalytic decomposition of perfluorooctanoic acid by transition-metal modified titanium dioxide

    Energy Technology Data Exchange (ETDEWEB)

    Chen, Meng-Jia; Lo, Shang-Lien, E-mail: sllo@ntu.edu.tw; Lee, Yu-Chi; Huang, Chang-Chieh

    2015-05-15

    Highlights: • Cu–TiO{sub 2} catalysts show much better catalytic activity than TiO{sub 2}. • The PFOA decomposition efficiencies reached 91% with UV/Cu–TiO{sub 2} system. • The intermediates of the PFOA decomposition reactions are detailed. - Abstract: Transition-metal modified TiO{sub 2} was used in a UV reactor to assist in decomposition of perfluorooctanoic acid (PFOA) in aqueous solutions. Comparing TiO{sub 2} and two types of metal-modified TiO{sub 2} (Fe–TiO{sub 2} and Cu–TiO{sub 2}), Cu–TiO{sub 2} exhibited the highest catalytic activity during PFOA decomposition and defluorination. After 12 h of reaction, the PFOA decomposition and defluorination efficiencies by the UV/Cu–TiO{sub 2} system reached 91% and 19%, respectively. PFOA was decomposed into fluoride ions (F{sup −}) and shorter perfluorinated carboxylic acids (PFCAs) such as C{sub 6}F{sub 13}COOH, C{sub 5}F{sub 11}COOH, C{sub 4}F{sub 9}COOH, C{sub 3}F{sub 7}COOH, C{sub 2}F{sub 5}COOH and CF{sub 3}COOH. The pseudo-first-order and pseudo-zero-order kinetics were used to model the decomposition and defluorination of PFOA, respectively. Rate constant values of PFOA decomposition for the UV/TiO{sub 2}, UV/Fe–TiO{sub 2}, and UV/Cu–TiO{sub 2} systems were 0.0001, 0.0015, and 0.0031 min{sup −1}, respectively, while rate constant values of PFOA defluorination for the UV/Fe–TiO{sub 2}, and UV/Cu–TiO{sub 2} systems were 0.0048 and 0.0077 mg/L·min{sup −1}, respectively. The photocatalysts were prepared by a photodeposition synthesis method and were characterized by scanning electron microscopy with energy-dispersive X-ray, X-ray diffraction and UV–vis spectrophotometry. The Fe–TiO{sub 2} and Cu–TiO{sub 2} catalysts exhibited considerably higher activities than that of TiO{sub 2}. The experimental results have demonstrated that the UV/Fe–TiO{sub 2} and UV/Cu–TiO{sub 2} systems could produce traps to capture photo-induced electrons, thereby reduce electron

  15. Spin-state chemistry of deuterated ammonia

    Science.gov (United States)

    Sipilä, O.; Harju, J.; Caselli, P.; Schlemmer, S.

    2015-09-01

    Aims: We aim to develop a chemical model that contains a consistent description of spin-state chemistry in reactions involving chemical species with multiple deuterons. We apply the model to the specific case of deuterated ammonia, to derive values for the various spin-state ratios. Methods: We applied symmetry rules in the context of the complete scrambling assumption to calculate branching ratio tables for reactions between chemical species that include multiple protons and/or deuterons. New reaction sets for both gas-phase and grain-surface chemistry were generated using an automated routine that forms all possible spin-state variants of any given reaction with up to six H/D atoms, using the predetermined branching ratios. Both a single-point and a modified Bonnor-Ebert model were considered to study the density and temperature dependence of ammonia and its isotopologs, and the associated spin-state ratios. Results: We find that the spin-state ratios of the ammonia isotopologs are, at late times, very different from their statistical values. The ratios are rather insensitive to variations in the density, but present strong temperature dependence. We derive high peak values (~0.1) for the deuterium fraction in ammonia, in agreement with previous (gas-phase) models. The deuterium fractionation is strongest at high density, corresponding to a high degree of depletion, and also presents temperature dependence. We find that in the temperature range 5 K to 20 K, the deuterium fractionation peaks at ~15 K, while most of the ortho/para (and meta/para for ND3) ratios present a minimum at 10 K (ortho/para NH2D has instead a maximum at this temperature). Conclusions: Owing to the density and temperature dependence found in the abundances and spin-state ratios of ammonia and its isotopologs, it is evident that observations of ammonia and its deuterated forms can provide important constraints on the physical structure of molecular clouds. Appendix A is available in

  16. A nonenzymatic biosensor based on gold electrodes modified with peptide self-assemblies for detecting ammonia and urea oxidation.

    Science.gov (United States)

    Bianchi, Roberta C; da Silva, Emerson Rodrigo; Dall'Antonia, Luiz H; Ferreira, Fabio Furlan; Alves, Wendel Andrade

    2014-09-30

    We have developed a nonenzymatic biosensor for the detection of ammonia and urea oxidation based on the deposition of peptide microstructures onto thiolated gold electrodes. FF-MNSs/MCP/Au assemblies were obtained by modifying gold substrates with 4-mercaptopyridine (MCP), followed by coating with l,l-diphenylalanine micro/nanostructures (FF-MNSs) grown in the solid-vapor phase. Benzene rings and amide groups with peptide micro/nanostructures interact with synthetic NH4(+) receptors through cation-π and hydrogen bonding. AuOH clusters on the Au surface provided the catalytic sites. The application of a predetermined concentration of analytes at the peptide interfaces activated the catalytic sites. We observed a relationship between the stability of films and the crystal structure of peptides, and we organized the FF-MNSs into an orthorhombic symmetry that was the most suitable assembly for creation of our biosensors. At 0.1 mol L(-1) NaOH, these FF-MNSs/MCP/Au electrodes have electrocatalytic properties regarding ammonia and urea oxidation that are comparable to those of enzyme-based architectures. Under optimal conditions, the electrocatalytic response is proportional to the ammonia and urea concentration in the range 0.1-1.0 mmol L(-1). The sensitivity was calculated as 2.83 and 81.3 μA mmol L(-1) cm(-2) for ammonia and urea, respectively, at +0.40 V (vs SCE). Our detection method is easy to follow, does not require a mediator or enzyme, and has strong potential for detecting urea via nonenzymatic routes. PMID:25188339

  17. Regeneration of ammonia borane spent fuel

    Energy Technology Data Exchange (ETDEWEB)

    Sutton, Andrew David [Los Alamos National Laboratory; Davis, Benjamin L [Los Alamos National Laboratory; Gordon, John C [Los Alamos National Laboratory

    2009-01-01

    A necessary target in realizing a hydrogen (H{sub 2}) economy, especially for the transportation sector, is its storage for controlled delivery, presumably to an energy producing fuel cell. In this vein, the U.S. Department of Energy's Centers of Excellence (CoE) in Hydrogen Storage have pursued different methodologies, including metal hydrides, chemical hydrides, and sorbents, for the expressed purpose of supplanting gasoline's current > 300 mile driving range. Chemical H{sub 2} storage has been dominated by one appealing material, ammonia borane (H{sub 3}N-BH{sub 3}, AB), due to its high gravimetric capacity of H{sub 2} (19.6 wt %) and low molecular weight (30.7 g mol{sup -1}). In addition, AB has both hydridic and protic moieties, yielding a material from which H{sub 2} can be readily released in contrast to the loss of H{sub 2} from C{sub 2}H{sub 6} which is substantially endothermic. As such, a number of publications have described H{sub 2} release from amine boranes, yielding various rates depending on the method applied. The viability of any chemical H{sub 2} storage system is critically dependent on efficient recyclability, but reports on the latter subject are sparse, invoke the use of high energy reducing agents, and suffer from low yields. Our group is currently engaged in trying to find and fully demonstrate an energy efficient regeneration process for the spent fuel from H{sub 2} depleted AB with a minimum number of steps. Although spent fuel composition depends on the dehydrogenation method, we have focused our efforts on the spent fuel resulting from metal-based catalysis, which has thus far shown the most promise. Metal-based catalysts have produced the fastest rates for a single equivalent of H{sub 2} released from AB and up to 2.5 equiv. of H{sub 2} can be produced within 2 hours. While ongoing work is being carried out to tailor the composition of spent AB fuel, a method has been developed for regenerating the predominant product

  18. Catalytic ozonation-biological coupled processes for the treatment of industrial wastewater containing refractory chlorinated nitroaromatic compounds*

    OpenAIRE

    Li, Bing-zhi; Xu, Xiang-Yang; Zhu, Liang

    2010-01-01

    A treatability study of industrial wastewater containing chlorinated nitroaromatic compounds (CNACs) by a catalytic ozonation process (COP) with a modified Mn/Co ceramic catalyst and an aerobic sequencing batch reactor (SBR) was investigated. A preliminary attempt to treat the diluted wastewater with a single SBR resulted in ineffective removal of the color, ammonia, total organic carbon (TOC) and chemical oxygen demand (COD). Next, COP was applied as a pretreatment in order to obtain a bio-c...

  19. Catalytic cracking of lignites

    Energy Technology Data Exchange (ETDEWEB)

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

    2013-11-01

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

  20. Catalytic Membrane Sensors

    Energy Technology Data Exchange (ETDEWEB)

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

    1998-12-01

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

  1. Catalytic gasification of biomass

    Science.gov (United States)

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

    1981-12-01

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

  2. D\\'ecompositions en hauteurs locales

    CERN Document Server

    Pazuki, Fabien

    2012-01-01

    Let A be an abelian variety defined over a number field k. We provide in this paper different decomposition formulas for the N\\'eron-Tate height of k-rational points on A. We deduce a decomposition of the Faltings height of the variety A itself. We also produce a local decomposition of the self-intersection of the relative dualizing sheaf (\\omega_C.\\omega_C) when A is the jacobian of a curve C.

  3. Decomposition of molybdenite products with nitric acid

    International Nuclear Information System (INIS)

    The problems of development abroad of hydrometallurgic methods of opening molybdenum concentrates using nitric acid are considered. Several variants of the process are developed, they are the two-stage decomposition by stoichiometrically necessary amount of nitric acid, single-stage decomposition in the avtoclave using nitric acid and oxigen as oxidizers; decomposition using circulatina nitro-sulfuric solution containing molybdenum. The advantages and disadvantages of new methods are presented

  4. Decomposition of molybdenite products with nitric acid

    Energy Technology Data Exchange (ETDEWEB)

    Nikitina, L.S.

    1983-04-01

    The problems of development abroad of hydrometallurgic methods of opening molybdenum concentrates using nitric acid are considered. Several variants of the process are developed, they are the two-stage decomposition by stoichiometrically necessary amount of nitric acid, single-stage decomposition in the autoclave using nitric acid and oxigen as oxidizers; decomposition using circulatina nitro-sulfuric solution containing molybdenum. The advantages and disadvantages of new methods are presented.

  5. Infrared multiphoton absorption and decomposition

    International Nuclear Information System (INIS)

    The discovery of infrared laser induced multiphoton absorption (IRMPA) and decomposition (IRMPD) by Isenor and Richardson in 1971 generated a great deal of interest in these phenomena. This interest was increased with the discovery by Ambartzumian, Letokhov, Ryadbov and Chekalin that isotopically selective IRMPD was possible. One of the first speculations about these phenomena was that it might be possible to excite a particular mode of a molecule with the intense infrared laser beam and cause decomposition or chemical reaction by channels which do not predominate thermally, thus providing new synthetic routes for complex chemicals. The potential applications to isotope separation and novel chemistry stimulated efforts to understand the underlying physics and chemistry of these processes. At ICOMP I, in 1977 and at ICOMP II in 1980, several authors reviewed the current understandings of IRMPA and IRMPD as well as the particular aspect of isotope separation. There continues to be a great deal of effort into understanding IRMPA and IRMPD and we will briefly review some aspects of these efforts with particular emphasis on progress since ICOMP II. 31 references

  6. Decomposition methods in turbulence research

    Directory of Open Access Journals (Sweden)

    Uruba Václav

    2012-04-01

    Full Text Available Nowadays we have the dynamical velocity vector field of turbulent flow at our disposal coming thanks advances of either mathematical simulation (DNS or of experiment (time-resolved PIV. Unfortunately there is no standard method for analysis of such data describing complicated extended dynamical systems, which is characterized by excessive number of degrees of freedom. An overview of candidate methods convenient to spatiotemporal analysis for such systems is to be presented. Special attention will be paid to energetic methods including Proper Orthogonal Decomposition (POD in regular and snapshot variants as well as the Bi-Orthogonal Decomposition (BOD for joint space-time analysis. Then, stability analysis using Principal Oscillation Patterns (POPs will be introduced. Finally, the Independent Component Analysis (ICA method will be proposed for detection of coherent structures in turbulent flow-field defined by time-dependent velocity vector field. Principle and some practical aspects of the methods are to be shown. Special attention is to be paid to physical interpretation of outputs of the methods listed above.

  7. Immigration process in catalytic medium

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

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

  8. Immigration process in catalytic medium

    Institute of Scientific and Technical Information of China (English)

    洪文明; 王梓坤

    2000-01-01

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

  9. Highly Scalable Matching Pursuit Signal Decomposition Algorithm

    Data.gov (United States)

    National Aeronautics and Space Administration — In this research, we propose a variant of the classical Matching Pursuit Decomposition (MPD) algorithm with significantly improved scalability and computational...

  10. Pattern decomposition of the transient climate response

    Directory of Open Access Journals (Sweden)

    Olivier Geoffroy

    2014-03-01

    Full Text Available A two-pattern decomposition of the mean surface air temperature response to an increase of CO2 is assessed. This decomposition is based on a two-layer global energy-balance model and the hypothesis of separability in space and time. It is shown that this decomposition allows the regional transient warming of a given atmosphere–ocean general circulation model to be well represented. The pattern decomposition is applied to 16 CMIP5 climate models and each of the two retrieved patterns – the equilibrium pattern and the pattern associated with the deep-ocean heat uptake – is described and discussed.

  11. Radiochemical decomposition of polychlorinated biphenyls in hexane

    International Nuclear Information System (INIS)

    Products of polychlorinated biphenyls (PCB) decomposition are analyzed with the aim of determining whether polychlorinated dibenzodioxins (PCDD) or dibenzafurans (PCDF) are formed during radition-chemical decomposition. It is shown that under irradiation of PCB Arochlor 1260 mixture with 10-2 mass % concentration decomposition degree equals 90.4 % at radiaion dose more than 6 Mrad. As the result of irradiation the content of relatively light PCB in the mixture increases and the content of irradiated mixture becomes close to the content of Arochlor 1242 mixture. Neitgher PCDD nor PCDE is detected on the products of PCB decomposition

  12. Operation summary of ammonia synthesis ammonia storage safety%合成氨氨库安全运行总结

    Institute of Scientific and Technical Information of China (English)

    周荷珍; 张志翠

    2014-01-01

    介绍了氨对人体健康的危害及急救措施、氨罐的操作、汽车氨罐卸氨的原理及具体操作、氨吸收塔的操作,指出只有对氨库实行科学管理和精心操作,才能保证氨库的长期安全稳定运行。%The paper introduces damage from ammonia on human health and emergency measures, ammonia tank operation, the principle of car unloading ammonia ammonia tank and the specific operation, ammonia absorption tower operation, points out that only the ammonia base of scientific management and careful operation, in order to ensure the long-term safe and stable operation of ammonia storage.

  13. Was early Mars warmed by ammonia?

    Science.gov (United States)

    Kasting, J. F.; Brown, L. L.; Acord, J. M.; Pollack, J. B.

    1992-01-01

    Runoff channels and valley networks present on ancient, heavily cratered Martian terrain suggests that the climate of Mars was originally warm and wet. One explanation for the formation of these channels is that the surface was warmed by the greenhouse effect of a dense, CO2 atmosphere. However, recent work shows that this theory is not consistent for the early period of the solar system. One way to increase the surface temperature predicted is to assume that other greenhouse gases were present in Mars' atmosphere in addition to CO2 and H2O. This possible gas is ammonia, NH3. If ammonia was present in sufficient quantities, it could have raised the surface temperature to 273 K. An adequate source would have been volcanic outgassing if the NH3 produced was shielded from photolysis by an ultraviolet light absorber.

  14. Computational Search for Improved Ammonia Storage Materials

    DEFF Research Database (Denmark)

    Jensen, Peter Bjerre; Lysgaard, Steen; Vegge, Tejs;

    . In this project we are searching for improved mixed materials with optimal desorption temperatures and kinetics, optimally releasing all ammonia in one step. We apply Density Functional Theory, DFT, calculations on mixed compounds selected by a Genetic Algorithm (GA), relying on biological principles of natural......Metal halide ammines, e.g. Mg(NH3)6Cl2 and Sr(NH3)8Cl2, can reversibly store ammonia, with high volumetric hydrogen storage capacities. The storage in the halide ammines is very safe, and the salts are therefore highly relevant as a carbon-free energy carrier in future transportation infrastructure...... selection. The GA is evolving from an initial (random) population and selecting those with highest fitness, a function based on e.g. stability, release temperature, storage capacity and the price of the elements. The search space includes all alkaline earth, 3d and 4d metals in combination with chloride...

  15. Modelling of Ammonia Heat Pump Desuperheaters

    DEFF Research Database (Denmark)

    Christensen, Stefan Wuust; Elmegaard, Brian; Markussen, Wiebke Brix;

    2015-01-01

    is that the specific heat is constant throughout the temperature glide of the refrigerant in the heat exchanger. However, considering ammonia as refrigerant, the LMTD method does not give accurate results due to significant variations of the specific heat. By comparing the actual temperature profiles from a one......This paper presents a study of modelling desuperheating in ammonia heat pumps. Focus is on the temperature profile of the superheated refrigerant. Typically, the surface area of a heat exchanger is estimated using the Log Mean Temperature Difference (LMTD) method. The assumption of this method....... The area of the heat exchanger can be increased or the condensation temperature can be raised to achieve the same temperature difference for the discretized model as for the LMTD. This would affect the compressor work, hence the COP of the system. Furthermore, for higher condenser pressure, and thus higher...

  16. System and method for selective catalytic reduction of nitrogen oxides in combustion exhaust gases

    Science.gov (United States)

    Sobolevskiy, Anatoly; Rossin, Joseph A

    2014-04-08

    A multi-stage selective catalytic reduction (SCR) unit (32) provides efficient reduction of NOx and other pollutants from about 50-550.degree. C. in a power plant (19). Hydrogen (24) and ammonia (29) are variably supplied to the SCR unit depending on temperature. An upstream portion (34) of the SCR unit catalyzes NOx+NH.sub.3 reactions above about 200.degree. C. A downstream portion (36) catalyzes NOx+H.sub.2 reactions below about 260.degree. C., and catalyzes oxidation of NH.sub.3, CO, and VOCs with oxygen in the exhaust above about 200.degree. C., efficiently removing NOx and other pollutants over a range of conditions with low slippage of NH.sub.3. An ammonia synthesis unit (28) may be connected to the SCR unit to provide NH.sub.3 as needed, avoiding transport and storage of ammonia or urea at the site. A carbonaceous gasification plant (18) on site may supply hydrogen and nitrogen to the ammonia synthesis unit, and hydrogen to the SCR unit.

  17. Spin-state chemistry of deuterated ammonia

    OpenAIRE

    Sipilä, O.; Harju, J.; Caselli, P.; Schlemmer, S.

    2015-01-01

    Aims. We aim to develop a chemical model that contains a consistent description of spin-state chemistry in reactions involving chemical species with multiple deuterons. We apply the model to the specific case of deuterated ammonia, to derive values for the various spin-state ratios. Methods. We apply symmetry rules in the complete scrambling assumption to calculate branching ratio tables for reactions between chemical species that include multiple protons and/or deuterons. Reaction sets for b...

  18. Nitrocarburising in ammonia-hydrocarbon gas mixtures

    DEFF Research Database (Denmark)

    Pedersen, Hanne; Christiansen, Thomas; Somers, Marcel A. J.

    2010-01-01

    The present work investigates the possibility of nitrocarburising in ammonia-acetylene-hydrogen and ammoniapropene- hydrogen gas mixtures, where unsaturated hydrocarbon gas is the carbon source during nitrocarburising. Consequently, nitrocarburising is carried out in a reducing atmosphere...... and straightforward control of the carburizing and nitriding potentials is in principle possible. The nitrocarburising response of unalloyed (ARMCO) Fe was investigated in a thermobalance during controlled nitrocarburising at 580°C. The “cases” obtained on nitrocarburised iron were characterized by reflected light...

  19. Manufacture of Catalyst Systems for Ammonia Conversion

    Institute of Scientific and Technical Information of China (English)

    GAKH S.V.; SAVENKOV D.A.

    2012-01-01

    Platinum catalyst gauzes have been in use since the moment of development of the process of catalyst oxidation of ammonia for production of nitric acid or hydrocyanic acid.Catalyst gauzes are usually made of platinum or its alloys with rhodium and palladium.These precious metals have remarkable properties that make them ideal catalysts for acceleration of the ammonia/oxygen reaction.In 2008,OJSC "SIC ‘Supermetal’" and Umicore AG&Co.KG launched a production line for Pt-alloy-based catalyst systems to be used for ammonia oxidation in the production of weak nitric acid.Catalyst systems consist of a pack of catalyst gauzes and a pack of catchment gauzes,which are made using flat-bed knitting machines and wire-cloth looms.Today,up-to-date catalyst systems MKSpreciseTM are being manufactured,the basic advantages of which are an individual structure of gauzes and composition of the material,which allows to define precisely the position of each gauze in the catalyst pack,a high activity of the catalyst pack,direct catching of platinum and rhodium in the catalyst system,and a reasonable combination of single- and multilayer types of gauzes.This makes it possible to vary the configuration of the catalyst and select an optimum composition of the system to ensure the maximum efficiency of the ammonia oxidation process.We also produce the catchment systems that allow to find the best decision from the economic point view for each individual case.

  20. Diverse microbial species survive high ammonia concentrations

    Science.gov (United States)

    Kelly, Laura C.; Cockell, Charles S.; Summers, Stephen

    2012-04-01

    Planetary protection regulations are in place to control the contamination of planets and moons with terrestrial micro-organisms in order to avoid jeopardizing future scientific investigations relating to the search for life. One environmental chemical factor of relevance in extraterrestrial environments, specifically in the moons of the outer solar system, is ammonia (NH3). Ammonia is known to be highly toxic to micro-organisms and may disrupt proton motive force, interfere with cellular redox reactions or cause an increase of cell pH. To test the survival potential of terrestrial micro-organisms exposed to such cold, ammonia-rich environments, and to judge whether current planetary protection regulations are sufficient, soil samples were exposed to concentrations of NH3 from 5 to 35% (v/v) at -80°C and room temperature for periods up to 11 months. Following exposure to 35% NH3, diverse spore-forming taxa survived, including representatives of the Firmicutes (Bacillus, Sporosarcina, Viridibacillus, Paenibacillus, Staphylococcus and Brevibacillus) and Actinobacteria (Streptomyces). Non-spore forming organisms also survived, including Proteobacteria (Pseudomonas) and Actinobacteria (Arthrobacter) that are known to have environmentally resistant resting states. Clostridium spp. were isolated from the exposed soil under anaerobic culture. High NH3 was shown to cause a reduction in viability of spores over time, but spore morphology was not visibly altered. In addition to its implications for planetary protection, these data show that a large number of bacteria, potentially including spore-forming pathogens, but also environmentally resistant non-spore-formers, can survive high ammonia concentrations.