22 results on '"Dornheim M"'
Search Results
2. On the chemical state and distribution of Zr- and V-based additives in reactive hydride composites.
- Author
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Bösenberg U, Vainio U, Pranzas PK, von Colbe JM, Goerigk G, Welter E, Dornheim M, Schreyer A, and Bormann R
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- Computer Simulation, Electric Power Supplies, Nanostructures ultrastructure, Particle Size, Hydrogen chemistry, Hydrogen isolation & purification, Models, Chemical, Nanostructures chemistry, Nanotechnology methods, Vanadium chemistry, Zirconium chemistry
- Abstract
Reactive hydride composites (RHCs) are very promising hydrogen storage materials for future applications due to their reduced reaction enthalpies and high gravimetric capacities. At present, the materials' functionality is limited by the reaction kinetics. A significant positive influence can be observed with addition of transition-metal-based additives. To understand the effect of these additives, the chemical state and changes during the reaction as well as the microstructural distribution were investigated using x-ray absorption near-edge structure (XANES) spectroscopy and anomalous small-angle x-ray scattering (ASAXS). In this work, zirconium- and vanadium-based additives were added to 2LiBH4-MgH2 composites and 2LiH-MgB2 composites and measured in the vicinity of the corresponding absorption edge. The measurements reveal the formation of finely distributed zirconium diboride and vanadium-based nanoparticles. The potential mechanisms for the observed influence on the reaction kinetics are discussed.
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- 2009
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3. Hydrogen-deuterium exchange experiments to probe the decomposition reaction of sodium alanate.
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Borgschulte A, Züttel A, Hug P, Barkhordarian G, Eigen N, Dornheim M, Bormann R, and Ramirez-Cuesta AJ
- Subjects
- Catalysis, Computer Simulation, Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization, Spectrum Analysis, Raman, Thermogravimetry, Aluminum Compounds chemistry, Deuterium chemistry, Deuterium Exchange Measurement, Hydrogen chemistry, Sodium Compounds chemistry
- Abstract
NaAlH(4) is the archetypical complex hydride for hydrogen storage. The extraordinary effect of dopants on the sorption kinetics triggered the investigation of this empirical finding. In this paper, a short review of the state of the art is given. To gain further understanding of the mechanisms involved we label the interacting species during the sorption process. This was experimentally realized by hydrogen-deuterium exchange measurements during the decomposition of NaAlH(4) followed by thermogravimetry, Raman spectroscopy and mass spectrometry. By these experiments we are able to obtain specific information on the diffusing species and formation of intermediates. The activation energy of tracer diffusion in NaAlH(4) is found to be 0.28 eV. The results are evidence for a vacancy-mediated desorption process of NaAlH(4).
- Published
- 2008
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4. Stress development in thin yttrium films on hard substrates during hydrogen loading.
- Author
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Dornheim, M., Pundt, A., Kirchheim, R., Molen, S. J. v. d., Kooij, E. S., Kerssemakers, J., Griessen, R., Harms, H., and Geyer, U.
- Subjects
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YTTRIUM , *THIN films , *SAPPHIRES , *HYDROGEN - Abstract
Polycrystalline (0002)-textured yttrium (Y) films of 50–500 nm thickness on sapphire substrates were loaded electrolytically with hydrogen (H). The stresses which build up in these films were measured in situ using curvature measurements. The results are compared to the behavior of bulk Y–H. A linear elastic model is used to predict the behavior of clamped thin films. Basic properties of the bulk Y–H phase diagram and elastic constants resemble the measured values of the thin films. Compressive stress builds up during H-loading in the α-Y phase and in the (α-Y+β-YH[sub 2]) two-phase field, showing an initial stress increase of -1.3 GPa per hydrogen concentration X[sub H] (compressive stress). While bulk Y–H samples are known to show a contraction in the β-YH[sub 2] phase during H loading, thin films show no evidence for such a contraction during the first loading cycle of the film. The stress remains constant in the bulk β-phase concentration range (ΔX[sub H]=0.1 H/Y). This is attributed to the narrow β-phase field (ΔX[sub H]=0.02 H/Y) of the thin film during the first loading. Only samples which have been kept at a hydrogen concentration of about 1.5 H/Y for weeks show tensile stress in the concentration range of the bulk β phase. Amazingly a stress increase of about +0.5 GPa/X[sub H] (tensile stress) is measured in the β+γ two-phase field. This is attributed to the smaller in-plane nearest-neighbor distance in the γ phase compared to the β phase. In the γ-phase field compressive stress is built up again, compensating the tensile stress. It increases by -1.3 GPa/X[sub H]. In total, the net stress in Y–H films remains comparably small. This could be a reason for the good mechanical stability of such Y–H switchable mirrors during H cycling. © 2003 American Institute of Physics. [ABSTRACT FROM AUTHOR]
- Published
- 2003
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5. Mg-based compounds for hydrogen and energy storage
- Author
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Crivello, J. -C., Denys, R. V., Dornheim, M., Felderhoff, M., Grant, D. M., Huot, J., Jensen, T. R., de Jongh, P., Latroche, M., Walker, G. S., Webb, C. J., Yartys, V. A., Sub Inorganic Chemistry and Catalysis, Inorganic Chemistry and Catalysis, Sub Inorganic Chemistry and Catalysis, and Inorganic Chemistry and Catalysis
- Subjects
Materials science ,Hydrogen ,Mg alloys ,Magnesium ,Inorganic chemistry ,chemistry.chemical_element ,02 engineering and technology ,General Chemistry ,Crystal structure ,010402 general chemistry ,021001 nanoscience & nanotechnology ,01 natural sciences ,Energy storage ,0104 chemical sciences ,Hydrogen storage ,chemistry ,Gravimetric analysis ,General Materials Science ,0210 nano-technology ,Chemical composition - Abstract
Magnesium-based alloys attract significant interest as cost-efficient hydrogen storage materials allowing the combination of high gravimetric storage capacity of hydrogen with fast rates of hydrogen uptake and release and pronounced destabilization of the metal–hydrogen bonding in comparison with binary Mg–H systems. In this review, various groups of magnesium compounds are considered, including (1) RE–Mg–Ni hydrides (RE = La, Pr, Nd); (2) Mg alloys with p-elements (X = Si, Ge, Sn, and Al); and (3) magnesium alloys with d-elements (Ti, Fe, Co, Ni, Cu, Zn, Pd). The hydrogenation–disproportionation–desorption–recombination process in the Mg-based alloys (LaMg12, LaMg11Ni) and unusually high-pressure hydrides synthesized at pressures exceeding 100 MPa (MgNi2H3) and stabilized by Ni–H bonding are also discussed. The paper reviews interrelations between the properties of the Mg-based hydrides and p–T conditions of the metal–hydrogen interactions, chemical composition of the initial alloys, their crystal structures, and microstructural state.
- Published
- 2016
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6. Review of magnesium hydride-based materials: development and optimisation
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Crivello, J. -C., Dam, B., Denys, R. V., Dornheim, M., Grant, D. M., Huot, J., Jensen, T. R., de Jongh, P., Latroche, M., Milanese, C., Milcius, D., Walker, G. S., Webb, C. J., Zlotea, C., Yartys, V. A., Inorganic Chemistry and Catalysis, and Sub Inorganic Chemistry and Catalysis
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Hydrogen ,Hydride ,Inorganic chemistry ,Magnesium hydride ,chemistry.chemical_element ,02 engineering and technology ,General Chemistry ,010402 general chemistry ,021001 nanoscience & nanotechnology ,01 natural sciences ,Decomposition ,0104 chemical sciences ,Catalysis ,chemistry.chemical_compound ,Hydrogen storage ,chemistry ,Chemical engineering ,Desorption ,Gravimetric analysis ,General Materials Science ,0210 nano-technology - Abstract
Magnesium hydride has been studied extensively for applications as a hydrogen storage material owing to the favourable cost and high gravimetric and volumetric hydrogen densities. However, its high enthalpy of decomposition necessitates high working temperatures for hydrogen desorption while the slow rates for some processes such as hydrogen diffusion through the bulk create challenges for large-scale implementation. The present paper reviews fundamentals of the Mg–H system and looks at the recent advances in the optimisation of magnesium hydride as a hydrogen storage material through the use of catalytic additives, incorporation of defects and an understanding of the rate-limiting processes during absorption and desorption.
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- 2016
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7. Ca(BH4)2–Mg2NiH4: on the pathway to a Ca(BH4)2 system with a reversible hydrogen cycle.
- Author
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Bergemann, N., Pistidda, C., Milanese, C., Emmler, T., Karimi, F., Chaudhary, A.-L., Chierotti, M. R., Klassen, T., and Dornheim, M.
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CALCIUM compounds ,HYDROGEN ,HYDRIDES ,HYDROGENATION ,CHEMICAL reactions - Abstract
The Ca(BH
4 )2 –Mg2 NiH4 system presented here is, to the best of our knowledge, the first described Ca(BH4 )2 -based hydride composite that reversibly transfers boron from the Ca-based compound(s) to the reaction partner. The ternary boride MgNi2.5 B2 is formed upon dehydrogenation and the formation of Ca(BH4 )2 upon rehydrogenation is confirmed. [ABSTRACT FROM AUTHOR]- Published
- 2016
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8. Hydrogen storage in magnesium-based hydrides and hydride composites
- Author
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Dornheim, M., Doppiu, S., Barkhordarian, G., Boesenberg, U., Klassen, T., Gutfleisch, O., and Bormann, R.
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HYDROGEN , *MAGNESIUM , *MECHANICAL alloying , *DYNAMICS - Abstract
Abstract: Mg and Mg-based hydrides have attracted much attention because of their high gravimetric hydrogen storage densities and favourable kinetic properties. Due to novel preparation methods and the development of suitable catalysts, hydrogen uptake and desorption is now possible within less than 2min. However, the hydrogen reaction enthalpy of pure Mg is too high for many applications, for example, for the zero emission car. Therefore, different routes are explored to tailor the hydrogen reaction enthalpy to potential applications. This article summarizes the recent developments concerning sorption properties and thermodynamics of Mg-based hydrides for hydrogen storage applications. In particular, promising strategies to decrease the hydrogen reaction enthalpy by alloying and the use of reactive hydride composites are discussed. [Copyright &y& Elsevier]
- Published
- 2007
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9. Magnesium based materials for hydrogen based energy storage: Past, present and future
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Yartys, V. A., Lototskyy, M. V., Akiba, E., Albert, R., Antonov, V. E., Ares, J. R., Baricco, M., Bourgeois, N., Buckley, C. E., Bellosta von Colbe, J. M., Crivello, J. C., Cuevas, F., Denys, R. V., Dornheim, M., Felderhoff, M., Grant, D. M., Hauback, B. C., Humphries, T. D., Jacob, I., Jensen, T. R., de Jongh, P. E., Joubert, J. M., Kuzovnikov, M. A., Latroche, M., Paskevicius, M., Pasquini, L., Popilevsky, L., Skripnyuk, V. M., Rabkin, E., Sofianos, M. V., Stuart, A., Walker, G., Wang, Hui, Webb, C. J., Zhu, Min, Inorganic Chemistry and Catalysis, Sub Inorganic Chemistry and Catalysis, Institute for Energy Technology, PO Box 40, 2007, Kjeller, Norway (INSTITUTE FOR ENERGY TECHNOLOGY, PO BOX 40, 2007, KJELLER, NORWAY), Institute for Energy Technology, PO Box 40, 2007, Kjeller, Norway, University of the Western Cape, Kyushu University [Fukuoka], Max-Planck-Institut für Kohlenforschung (Coal Research), Max-Planck-Gesellschaft, Institute of Solid State Physics (ISSP, RAS), Russian Academy of Sciences [Moscow] (RAS), Universidad Autonoma de Madrid (UAM), Dipartimento di Chimica IFM, Università degli studi di Torino (UNITO), Institut de Chimie et des Matériaux Paris-Est (ICMPE), Institut de Chimie du CNRS (INC)-Université Paris-Est Créteil Val-de-Marne - Paris 12 (UPEC UP12)-Centre National de la Recherche Scientifique (CNRS), Curtin University [Perth], Planning and Transport Research Centre (PATREC), Helmholtz-Zentrum Geesthacht (GKSS), University of Nottingham, UK (UON), Ben-Gurion University of the Negev (BGU), Interdisciplinary Nanoscience Center (iNANO), Aarhus University [Aarhus], Utrecht University [Utrecht], Max Planck Institute for Chemistry (MPIC), University of Bologna [Italy], Technion - Israel Institute of Technology [Haifa], South China University of Technology [Guangzhou] (SCUT), Griffith University [Brisbane], Inorganic Chemistry and Catalysis, Sub Inorganic Chemistry and Catalysis, Osipyan Institute of Solid State Physics (ISSP), Universidad Autónoma de Madrid (UAM), Università degli studi di Torino = University of Turin (UNITO), Université Paris-Est Créteil Val-de-Marne - Paris 12 (UPEC UP12)-Centre National de la Recherche Scientifique (CNRS)-Institut de Chimie du CNRS (INC), Yartys, V.A., Lototskyy, M.V., Akiba, E., Albert, R., Antonov, V.E., Ares, J.R., Baricco, M., Bourgeois, N., Buckley, C.E., Bellosta von Colbe, J.M., Crivello, J.-C., Cuevas, F., Denys, R.V., Dornheim, M., Felderhoff, M., Grant, D.M., Hauback, B.C., Humphries, T.D., Jacob, I., Jensen, T.R., de Jongh, P.E., Joubert, J.-M., Kuzovnikov, M.A., Latroche, M., Paskevicius, M., Pasquini, L., Popilevsky, L., Skripnyuk, V.M., Rabkin, E., Sofianos, M.V., Stuart, A., Walker, G., Wang, Hui, Webb, C.J., and Zhu, Min
- Subjects
Magnesium-based hydrides ,Materials science ,Hydrogen ,chemistry.chemical_element ,Energy Engineering and Power Technology ,02 engineering and technology ,Solid material ,Applications ,Catalysis ,High pressures ,Kinetics ,Nanostructuring ,Renewable Energy, Sustainability and the Environment ,Fuel Technology ,Condensed Matter Physics ,010402 general chemistry ,Thermal energy storage ,01 natural sciences ,7. Clean energy ,Energy storage ,Catalysi ,Hydrogen storage ,chemistry.chemical_compound ,Renewable Energy ,Process engineering ,Kinetic ,Sustainability and the Environment ,Magnesium ,business.industry ,Magnesium hydride ,[CHIM.MATE]Chemical Sciences/Material chemistry ,021001 nanoscience & nanotechnology ,0104 chemical sciences ,High pressure ,chemistry ,13. Climate action ,Magnesium-based hydride ,0210 nano-technology ,business - Abstract
Magnesium hydride owns the largest share of publications on solid materials for hydrogen storage. The “Magnesium group” of international experts contributing to IEA Task 32 “Hydrogen Based Energy Storage” recently published two review papers presenting the activities of the group focused on magnesium hydride based materials and on Mg based compounds for hydrogen and energy storage. This review article not only overviews the latest activities on both fundamental aspects of Mg-based hydrides and their applications, but also presents a historic overview on the topic and outlines projected future developments. Particular attention is paid to the theoretical and experimental studies of Mg-H system at extreme pressures, kinetics and thermodynamics of the systems based on MgH 2 , nanostructuring, new Mg-based compounds and novel composites, and catalysis in the Mg based H storage systems. Finally, thermal energy storage and upscaled H storage systems accommodating MgH 2 are presented.
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10. Improved hydrogen sorption of sodium alanate by optimized processing
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Eigen, N., Gosch, F., Dornheim, M., Klassen, T., and Bormann, R.
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NANOCRYSTALS , *NANOSTRUCTURES , *NANOPARTICLES , *HYDROGEN - Abstract
Abstract: This work demonstrates that fast sorption kinetics in complex hydrides can be achieved by a simple synthesis method using cost-efficient initial components, if microstructure and powder morphology are optimized. NaH/Al precursors with TiCl4 catalyst were synthesised under varying conditions in argon atmosphere and cycled. The influence of powder morphology and microstructure resulting from different process conditions were studied in detail. It is shown that a homogeneous mixing of the phases and a high surface area of the material is essential for fast kinetics and high reversible capacity. The optimized process can be easily scaled up to a cost-efficient production process for large amounts of storage material and can also be applied for other complex hydrides. [Copyright &y& Elsevier]
- Published
- 2008
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11. Waste Mg-Al based alloys for hydrogen storage.
- Author
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Hardian, R., Pistidda, C., Chaudhary, A.-L., Capurso, G., Gizer, G., Cao, H., Milanese, C., Girella, A., Santoru, A., Yigit, D., Dieringa, H., Kainer, K.U., Klassen, T., and Dornheim, M.
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HYDROGEN storage , *MAGNESIUM alloys , *NIOBIUM oxide , *SORPTION , *MICROSTRUCTURE - Abstract
Magnesium has been studied as a potential hydrogen storage material for several decades because of its relatively high hydrogen storage capacity, fast sorption kinetics (when doped with transition metal based additives), and abundance. This research aims to study the possibility to use waste magnesium alloys to produce good quality MgH 2 . The production costs of hydrogen storage materials is still one of the major barriers disabling scale up for mobile or stationary application. The recycling of magnesium-based waste to produce magnesium hydride will significantly contribute to the cost reduction of this material. This study focuses on the effect of different parameters such as the addition of graphite and/or Nb 2 O 5 as well as the effect of milling time on the material hydrogenation/de-hydrogenation performances. In addition, morphology and microstructural features are also evaluated for all the investigated materials. [ABSTRACT FROM AUTHOR]
- Published
- 2018
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12. Scattering influences in quantitative fission neutron radiography for the in situ analysis of hydrogen distribution in metal hydrides.
- Author
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Börries, S., Metz, O., Pranzas, P.K., Bücherl, T., Söllradl, S., Dornheim, M., Klassen, T., and Schreyer, A.
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NEUTRON radiography , *NUCLEAR fission , *HYDROGEN , *HYDRIDES , *ATTENUATION coefficients , *SCATTERING (Physics) - Abstract
In situ neutron radiography allows for the time-resolved study of hydrogen distribution in metal hydrides. However, for a precise quantitative investigation of a time-dependent hydrogen content within a host material, an exact knowledge of the corresponding attenuation coefficient is necessary. Additionally, the effect of scattering has to be considered as it is known to violate Beer׳s law, which is used to determine the amount of hydrogen from a measured intensity distribution. Within this study, we used a metal hydride inside two different hydrogen storage tanks as host systems, consisting of steel and aluminum. The neutron beam attenuation by hydrogen was investigated in these two different setups during the hydrogen absorption process. A linear correlation to the amount of absorbed hydrogen was found, allowing for a readily quantitative investigation. Further, an analysis of scattering contributions on the measured intensity distributions was performed and is described in detail. [ABSTRACT FROM AUTHOR]
- Published
- 2015
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13. Sorption and desorption properties of a CaH{sub 2}/MgB{sub 2}/CaF{sub 2} reactive hydride composite as potential hydrogen storage material
- Author
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Dornheim, M [Institute of Materials Research, Materials Technology, Helmholtz-Zentrum Geesthacht, D-21502 Geesthacht (Germany)]
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- 2011
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14. Sorption and desorption properties of a CaH2/MgB2/CaF2 reactive hydride composite as potential hydrogen storage material
- Author
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Suarez Alcantara, K., Boesenberg, U., Zavorotynska, O., Bellosta von Colbe, J., Taube, K., Baricco, M., Klassen, T., and Dornheim, M.
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DESORPTION , *CALCIUM compounds , *MAGNESIUM compounds , *ENERGY storage , *HYDROGEN , *COMPOSITE materials , *HYDROGENATION , *X-ray diffraction - Abstract
Abstract: The hydrogenation behavior of 3CaH2+4MgB2+CaF2 composite was studied by manometric measurements, powder X-ray diffraction, differential scanning calorimetry and attenuated total reflection infrared spectroscopy. The maximum observed quantity of hydrogen loaded in the composite was 7.0wt%. X-ray diffraction showed the formation of Ca(BH4)2 and MgH2 after hydrogenation. The activation energy for the dehydrogenation reaction was evaluated by DSC measurements and turns out to be 162±15kJmol−1 H2. This value decreases due to cycling to 116±5kJmol−1 H2 for the third dehydrogenation step. A decrease of ca. 25–50°C in dehydrogenation temperature was observed with cycling. Due to its high capacity and reversibility, this composite is a promising candidate as a potential hydrogen storage material. [Copyright &y& Elsevier]
- Published
- 2011
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15. Activation of the reactive hydride composite 2NaBH4 +MgH2
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Pistidda, C., Barkhordarian, G., Rzeszutek, A., Garroni, S., Minella, C. Bonatto, Baró, M.D., Nolis, P., Bormann, Rüdiger, Klassen, T., and Dornheim, M.
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HYDRIDES , *NUCLEAR magnetic resonance , *HYDROGEN , *DIFFUSION , *CHEMICAL reactions , *DESORPTION , *MIXTURES , *COMPOSITE materials - Abstract
A novel method to enhance the reaction kinetics of the reactive hydride composite 2NaBH4 +MgH2 is described. It has been discovered that short-term exposure to a moist atmosphere has a very beneficial effect on the desorption reaction of the 2NaBH4 +MgH2 mixture. By this procedure it is possible to achieve, after drying, both faster desorption kinetics and greater amounts of released hydrogen compared to ball-milled material without further treatment. [ABSTRACT FROM AUTHOR]
- Published
- 2011
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16. Sorption properties of NaBH4/MH2 (M=Mg, Ti) powder systems
- Author
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Garroni, S., Milanese, C., Girella, A., Marini, A., Mulas, G., Menéndez, E., Pistidda, C., Dornheim, M., Suriñach, S., and Baró, M.D.
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HYDROGEN , *ENERGY storage , *HYDRIDES , *ABSORPTION , *METAL powders , *TERNARY phase diagrams , *METALLIC composites - Abstract
Abstract: The sorption properties of NaBH4/MH2 (M=Mg, Ti) powder systems prepared by high-energy ball milling have been thoroughly investigated. Concerning the systems containing MgH2, the 2:1 and 1:2 molar compositions have been studied and both lead to a multi-step desorption pathway, where the formation of MgB2 confirms the destabilization of NaBH4 induced by the presence of MgH2. A noticeable kinetic enhancement is achieved for the MgH2-rich system (composition 1:2) if compared with the NaBH4-rich system (composition 2:1). Even though full re-absorption is obtained for neither of the two compositions, fast kinetics is achieved. During absorption, the unsuspected formation of the perovskite-type hydride NaMgH3 is detected and it is showed that this ternary phase contributes to reduce the gravimetric capacity of the systems. Conversely, in the 2NaBH4/TiH2 system, there is no formation of the intermetallic compound TiB2. Furthermore, a decrease in the sorption kinetics is found in comparison with the systems based on MgH2. [Copyright &y& Elsevier]
- Published
- 2010
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17. Reversible hydrogen storage in NaF–Al composites
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Eigen, N., Bösenberg, U., Bellosta von Colbe, J., Jensen, T.R., Cerenius, Y., Dornheim, M., Klassen, T., and Bormann, R.
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COMPOSITE materials , *SODIUM fluoride , *HYDRIDES , *HYDROGEN , *HEAT of formation , *NEUTRON diffraction , *REACTION mechanisms (Chemistry) , *X-ray diffraction - Abstract
Abstract: This work demonstrates that hydrogen can be reversibly stored in a composite of NaF and Al. NaF and Al reacts to a mixture of Na3AlF6 and NaAlH4 via hydridofluoride phases of the form Na3AlH6−x F x . The analysis of thermodynamics based on literature standard enthalpies of formation yields the technically favourable enthalpy of reaction of roughly 35kJ/molH2 for a theoretical gravimetric hydrogen storage capacity of 3.3wt%. Reaction mechanisms are discussed with respect to substitution of hydrogen by fluorine in complex hydrides. [Copyright &y& Elsevier]
- Published
- 2009
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18. Hydrogen dissociation on oxide covered MgH2 by catalytically active vacancies
- Author
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Borgschulte, A., Bielmann, M., Züttel, A., Barkhordarian, G., Dornheim, M., and Bormann, R.
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HYDROGEN , *OXIDES , *PHOTOELECTRON spectroscopy , *ELECTRON spectroscopy - Abstract
Abstract: MgH2 is an important ingredient in modern reactive hydride composites to be used as hydrogen storage materials. The surface composition and chemical state of ball-milled MgH2 is studied during hydrogen desorption by means of X-ray photoelectron spectroscopy. Simultaneously, the desorption rate of hydrogen is monitored, which is compared to dissociative properties of the surface investigated by hydrogen–deuterium exchange experiments. It is found that MgH2 is also oxide covered during desorption demonstrating that MgO is able to recombine atomic hydrogen. The corresponding catalytic sites are associated with low coordinated surface vacancies on the oxide. The maximum surface concentration of these vacancies is very small, which is countered by a very high turnover frequency due to a small activation energy for dissociation of hydrogen of 0.1eV on the single vacancy. The study provides insight into the catalytic role played by the oxide additives in MgH2, which are superior catalysts for hydrogen sorption even when compared to 3d-metals. [Copyright &y& Elsevier]
- Published
- 2008
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19. Enhanced hydrogen sorption kinetics of magnesium by destabilized MgH2−δ
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Borgschulte, A., Bösenberg, U., Barkhordarian, G., Dornheim, M., and Bormann, R.
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HYDROGEN , *NONMETALS , *HYDROGENATION , *CHEMICAL inhibitors - Abstract
Abstract: The kinetics of the reversible reaction of hydrogen gas with magnesium forming MgH2 is enhanced significantly by the addition of transition metals oxide catalysts and by using nanostructured powders. Hydrogen absorption and desorption properties of such systems were studied by differential scanning calorimetry (DSC) under hydrogen atmosphere, from which the heat of hydride formation and decomposition is determined. Apart from Mg and stoichiometric MgH2, we find an additional, slightly destabilized phase, which is formed prior to MgH2 upon hydrogenation. The amount of this phase depends on the degree of nanostructuring and the used additive. X-ray diffraction measurements confirm the compared to MgH2 slightly different lattice parameters of the intermediate phase. The results correspond to recent neutron diffraction measurements, by which a new MgH2−δ phase was found. We propose that this destabilized phase acts as a gateway for de-hydrogenation of MgH2. [Copyright &y& Elsevier]
- Published
- 2007
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20. The catalytic effect of Nb2O5 on the electrochemical hydrogenation of nanocrystalline magnesium
- Author
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Zander, D., Lyubenova, L., Köster, U., Dornheim, M., Aguey-Zinsou, F., and Klassen, T.
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HYDROGEN , *HYDRIDES , *NONMETALS , *ELECTRIC resistors - Abstract
Abstract: Nanocrystalline Mg powder without and with 2mol% Nb2O5 catalyst was studied in a 6M KOH electrolyte as electrode material for electrochemical hydrogen charging processes. Since the hydrogen overpotential of Mg, which is a measure of the hydrogen evolution at the electrode surface, was observed to be reduced by the addition of Nb2O5, it is assumed that the catalyst influences the electrode reactions. Considering this assumption hydrogenation was studied at different current densities. The storage capacity as well as the kinetic of Mg/Nb2O5 electrodes increased significantly up to 1wt.% H2 at a charging time of 30min with decreasing current density. The storage capacity of nanocrystalline Mg powder showed only minor changes to lower hydrogen contents with decreasing current density. [Copyright &y& Elsevier]
- Published
- 2006
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21. Application of Hydrides in Hydrogen Storage and Compression: Achievements, Outlook and Perspectives
- Author
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Marcello Baricco, Torben R. Jensen, Julian Jepsen, Alastair D. Stuart, José M. Bellosta von Colbe, José R. Ares, Mykhaylol V. Lototskyy, Amelia Montone, Craig E. Buckley, Giovanni Capurso, David M. Grant, Thomas Klassen, H.N. Yang, I. Jacob, Jussara Barale, Volodymyr A. Yartys, Drew A. Sheppard, Gavin S. Walker, Kandavel Manickam, Colin J. Webb, Julián Puszkiel, Sabrina Sartori, Matylda N. Guzik, Andreas Züttel, Noris Gallandat, Emil H. Jensen, Martin Dornheim, UAM. Departamento de Física de Materiales, Bellosta von Colbe, J., Ares, J. -R., Barale, J., Baricco, M., Buckley, C., Capurso, G., Gallandat, N., Grant, D. M., Guzik, M. N., Jacob, I., Jensen, E. H., Jensen, T., Jepsen, J., Klassen, T., Lototskyy, M. V., Manickam, K., Montone, A., Puszkiel, J., Sartori, S., Sheppard, D. A., Stuart, A., Walker, G., Webb, C. J., Yang, H., Yartys, V., Zuttel, A., and Dornheim, M.
- Subjects
Materiales / Ciencia de los Materiales ,Materials science ,Hydrogen ,Intermetallic ,chemistry.chemical_element ,Energy Engineering and Power Technology ,02 engineering and technology ,010402 general chemistry ,01 natural sciences ,7. Clean energy ,Energy storage ,Metal ,Hydrogen storage ,Hydrogen compression ,Metal hydrides ,Renewable Energy ,Process engineering ,ddc:620.11 ,Sustainability and the Environment ,Renewable Energy, Sustainability and the Environment ,business.industry ,Hydride ,Física ,Fuel Technology ,Condensed Matter Physics ,021001 nanoscience & nanotechnology ,0104 chemical sciences ,chemistry ,purl.org/becyt/ford/2 [https] ,visual_art ,visual_art.visual_art_medium ,0210 nano-technology ,business ,purl.org/becyt/ford/2.5 [https] ,Gas compressor ,Thermal energy - Abstract
Metal hydrides are known as a potential efficient, low-risk option for high-density hydrogen storage since the late 1970s. In this paper, the present status and the future perspectives of the use of metal hydrides for hydrogen storage are discussed. Since the early 1990s, interstitial metal hydrides are known as base materials for Ni – metal hydride rechargeable batteries. For hydrogen storage, metal hydride systems have been developed in the 2010s [1] for use in emergency or backup power units, i. e. for stationary applications. With the development and completion of the first submarines of the U212 A series by HDW (now Thyssen Krupp Marine Systems) in 2003 and its export class U214 in 2004, the use of metal hydrides for hydrogen storage in mobile applications has been established, with new application fields coming into focus. In the last decades, a huge number of new intermetallic and partially covalent hydrogen absorbing compounds has been identified and partly more, partly less extensively characterized. In addition, based on the thermodynamic properties of metal hydrides, this class of materials gives the opportunity to develop a new hydrogen compression technology. They allow the direct conversion from thermal energy into the compression of hydrogen gas without the need of any moving parts. Such compressors have been developed and are nowadays commercially available for pressures up to 200 bar. Metal hydride based compressors for higher pressures are under development. Moreover, storage systems consisting of the combination of metal hydrides and high-pressure vessels have been proposed as a realistic solution for on-board hydrogen storage on fuel cell vehicles. In the frame of the “Hydrogen Storage Systems for Mobile and Stationary Applications” Group in the International Energy Agency (IEA) Hydrogen Task 32 “Hydrogen-based energy storage” different compounds have been and will be scaled-up in the near future and tested in the range of 500 g to several hundred kg for use in hydrogen storage applications, The research for the lab-scale compressor is part of the activities of SCCER HaE, which is financially supported by Innosuisse - Swiss Innovation Agency . The authors thank the Alexander von Humboldt Foundation in the frame of the post-doctoral fellowship of Dr. J. Puszkiel (No. 1187279 STP ) as well as the European Union for their funding of projects STORHY (contract Nr. SES6-CT-2004-502667 , FP6-2002-Energy-1, 6.1.3.2.2), NESSHY (contract Nr. 518271 , FP6-2004-Energy-3, 6.1.3.2.2) and the EU Horizon 2020 /RISE project HYDRIDE4MOBILITY. Financial support from the S02 and KP8 S05), the European Union's Seventh Framework Programme ( FP7/2007e2013 ) for the Fuel Cells and Hydrogen Joint Technology Initiative under grant agreement no. 256653 (SSH2S), from the European Fuel Cells and Hydrogen Joint Undertaking in the framework of BOR4STORE (Grant agreement no. 303428 ), from the Australian Research Council for grants LP120101848 , LP150100730 , and LE0989180 , The Innovation Fund Denmark (project HyFill-Fast), DST within Hydrogen South Africa/HySA programme (projects KP3 National Research Foundation/NRF of South Africa , incentive funding grant number 109092 and the Research Council of Norway (project 285147 ) is thankfully acknowledged
- Published
- 2019
- Full Text
- View/download PDF
22. Influence of the Nb2O5 distribution on the electrochemical hydrogenation of nanocrystalline magnesium
- Author
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Zander, D., Lyubenova, L., Köster, U., Klassen, T., and Dornheim, M.
- Subjects
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NATIVE element minerals , *HYDROGEN , *NONMETALS , *HYDROGENATION - Abstract
Abstract: Nanocrystalline Mg powder without and with 2mol% Nb2O5 catalyst was studied as an electrode material for electrochemical hydrogen charging in a 6M KOH electrolyte. A strong influence of the compaction parameters, the current density and the catalyst on the hydrogenation behavior was observed. The addition of graphite and PTFE to the Mg/Nb2O5 electrodes improves the charging kinetics as well as the hydrogen content. The hydrogen contents achieved in Mg with Nb2O5, however, show a broad scatter. It was concluded that the catalyst distribution influences the upper limit of the storage capacity as well as the oxidation process at the surface during preparation. Since the addition of Nb2O5 was observed to reduce the hydrogen overpotential of Mg depending on the catalyst distribution, it is assumed that the catalyst influences the electrode reactions. Therefore, hydrogenation was investigated for different Nb2O5 distributions at different current densities in detail. [Copyright &y& Elsevier]
- Published
- 2007
- Full Text
- View/download PDF
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