Hydrogen Temperature-Programmed Desorption (H2 TPD) of Supported Platinum Catalysts.

NARCIS (Netherlands)

Koningsberger, D.C.; Miller, J.T.; Meyers, B.L.; Modica, F.S.; Lane, G.S.; Vaarkamp, M.

1993-01-01

Hydrogen temperature-programmed desorption (TPD) of supported platinum catalysts, Pt/KLTL, Pt/H-LTL, Pt/K-MAZ, Pt/H-MAZ, Pt/-Al2O3, and Pt/SiO2, was performed after hydrogen reduction at 300, 450, or 650°C. For all catalysts, reversible desorption of chemisorbed hydrogen occurred at approximately

The Absorption-Desorption of Hydrogen by 1.5 g Depleted Uranium

Energy Technology Data Exchange (ETDEWEB)

Kim, Sunmi; Paek, Seungwoo; Lee, Minsoo; Kim, Si-Hyung; Kim, Kwang-Rag; Ahn, Do-Hee [Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of); Sohn, Soon Hwan; Song, Kyu Min [Korea Electric Power Research Institute, Daejeon (Korea, Republic of)

2008-10-15

The form of metal tritides is one of the most popular methods for the storage of hydrogen isotopes. Particularly when metal is in a powder form, the storage capacity of hydrogen isotopes become the maximum value. Here, a 1.5g depleted uranium metal was decrepitated into a powder upon an absorption and desorption of hydrogen gas. The conditions for an activation, absorption-desorption of the hydrogen were defined.

The Absorption-Desorption of Hydrogen by 1.5 g Depleted Uranium

International Nuclear Information System (INIS)

Kim, Sunmi; Paek, Seungwoo; Lee, Minsoo; Kim, Si-Hyung; Kim, Kwang-Rag; Ahn, Do-Hee; Sohn, Soon Hwan; Song, Kyu Min

2008-01-01

The form of metal tritides is one of the most popular methods for the storage of hydrogen isotopes. Particularly when metal is in a powder form, the storage capacity of hydrogen isotopes become the maximum value. Here, a 1.5g depleted uranium metal was decrepitated into a powder upon an absorption and desorption of hydrogen gas. The conditions for an activation, absorption-desorption of the hydrogen were defined

Beneficial effect of carbon on hydrogen desorption kinetics from Mg–Ni–In alloy

International Nuclear Information System (INIS)

Cermak, J.; Kral, L.

2013-01-01

Highlights: ► Beneficial effect of graphitic carbon was observed. ► The effect is optimal up to c opt . ► Above c opt , phase decomposition occurs. ► Indium in studied Mg–Ni-based alloys prevents oxidation. - Abstract: In the present paper, hydrogen desorption kinetics from hydrided Mg–Ni–In–C alloys was investigated. A chemical composition that substantially accelerates hydrogen desorption was found. It was observed that carbon improves the hydrogen desorption kinetics significantly. Its beneficial effect was found to be optimum close to the carbon concentration of about c C ≅ 5 wt.%. With this composition, stored hydrogen can be desorbed readily at temperatures down to about 485 K, immediately after hydrogen charging. This can substantially shorten the hydrogen charging/discharging cycle of storage tanks using Mg–Ni-based alloys as hydrogen storage medium. For higher carbon concentrations, unwanted phases precipitated, likely resulting in deceleration of hydrogen desorption and lower hydrogen storage capacity.

Hydrogen desorption reactions of Li-N-H hydrogen storage system: Estimation of activation free energy

International Nuclear Information System (INIS)

Matsumoto, Mitsuru; Haga, Tetsuya; Kawai, Yasuaki; Kojima, Yoshitsugu

2007-01-01

The dehydrogenation reactions of the mixtures of lithium amide (LiNH 2 ) and lithium hydride (LiH) were studied under an Ar atmosphere by means of temperature programmed desorption (TPD) technique. The dehydrogenation reaction of the LiNH 2 /LiH mixture was accelerated by addition of 1 mol% Ti(III) species (k = 3.1 x 10 -4 s -1 at 493 K), and prolonged ball-milling time (16 h) further enhanced reaction rate (k = 1.1 x 10 -3 s -1 at 493 K). For the hydrogen desorption reaction of Ti(III) doped samples, the activation energies estimated by Kissinger plot (95 kJ mol -1 ) and Arrhenius plot (110 kJ mol -1 ) were in reasonable agreement. The LiNH 2 /LiH mixture without Ti(III) species, exhibited slower hydrogen desorption process and the kinetic traces deviated from single exponential behavior. The results indicated the Ti(III) additives change the hydrogen desorption reaction mechanism of the LiNH 2 /LiH mixture

GaN CVD Reactions: Hydrogen and Ammonia Decomposition and the Desorption of Gallium

International Nuclear Information System (INIS)

Bartram, Michael E.; Creighton, J. Randall

1999-01-01

Isotopic labeling experiments have revealed correlations between hydrogen reactions, Ga desorption, and ammonia decomposition in GaN CVD. Low energy electron diffraction (LEED) and temperature programmed desorption (TPD) were used to demonstrate that hydrogen atoms are available on the surface for reaction after exposing GaN(0001) to deuterium at elevated temperatures. Hydrogen reactions also lowered the temperature for Ga desorption significantly. Ammonia did not decompose on the surface before hydrogen exposure. However, after hydrogen reactions altered the surface, N 15 H 3 did undergo both reversible and irreversible decomposition. This also resulted in the desorption of N 2 of mixed isotopes below the onset of GaN sublimation, This suggests that the driving force of the high nitrogen-nitrogen bond strength (226 kcal/mol) can lead to the removal of nitrogen from the substrate when the surface is nitrogen rich. Overall, these findings indicate that hydrogen can influence G-aN CVD significantly, being a common factor in the reactivity of the surface, the desorption of Ga, and the decomposition of ammonia

Investigation of hydrogen-deformation interactions in β-21S titanium alloy using thermal desorption spectroscopy

International Nuclear Information System (INIS)

Tal-Gutelmacher, E.; Eliezer, D.; Boellinghaus, Th.

2007-01-01

The focus of this paper is the investigation of the combined influence of hydrogen and pre-plastic deformation on hydrogen's absorption/desorption behavior, the microstructure and microhardness of a single-phased β-21S alloy. In this study, thermal desorption analyses (TDS) evaluation of various desorption and trapping parameters provide further insight on the relationships between hydrogen absorption/desorption processes and deformation, and their mutual influence on the microstructure and the microhardness of β-21S alloy. TDS spectra were supported by other experimental techniques, such as X-ray diffraction, scanning and transmission electron microscopy, hydrogen quantity analyses and microhardness tests. Pre-plastic deformation, performed before the electrochemical hydrogenation of the alloy, increased significantly the hydrogen absorption capacity. Its influence was also evident on the notably expanded lattice parameter of β-21S alloy after hydrogenation. However, no hydride precipitation was observed. An interesting softening effect of the pre-deformed hydrogenated alloy was revealed by microhardness tests. TDS demonstrated the significant effect of pre-plastic deformation on the hydrogen evolution process. Hydrogen desorption temperature and the activation energy for hydrogen release increased, additional trap states were observed and the amount of desorbed hydrogen decreased

Thermal desorption spectroscopy for investigating hydrogen isotope behavior in materials

International Nuclear Information System (INIS)

Xia Tirui; Yang Hongguang; Zhan Qin; Han Zhibo; He Changshui

2012-01-01

The behavior of hydrogen isotope generated in fusion reactor materials is the key issue for safety and economic operation of fusion reactors and becomes an interesting field. In order to investigate the mechanism of hydrogen isotope such as diffusion, release and retention, a high-sensitivity thermal desorption spectroscopy (TDS) in combination with a quadruple mass spectrometer (QMS) was developed. A major technical breakthrough in ultrahigh vacuum (UHV), low hydrogen background, linear heating and sensitivity calibration of TDS system was made. UHV of l × 10 -7 Pa and low hydrogen background of l × 10 -9 Pa were obtained by combining turbo molecule pump and sputter ion pump. Specimens can be linearly heated up to 1173 K at the rate of 1 to 50 K/min under the MCGS PID software. Sensitivity calibration of the TDS system was accomplished using a special deuterium leak in the detector mode of QMS second electron multiplier. The desorption sensitivity coefficient and the minimum detection limit of deuterium desorption rate are 6.22 × l0 24 s -l · and l.24 × l0 -10 s -1 , respectively. The measurement was also routinely conducted on a specimen of standard, deuterium-containing Zr-4 alloy maintained in the laboratory, so as to validate the TDS method. (authors)

Hydrogen adsorption and desorption with 3D silicon nanotube-network and film-network structures: Monte Carlo simulations

International Nuclear Information System (INIS)

Li, Ming; Kang, Zhan; Huang, Xiaobo

2015-01-01

Hydrogen is clean, sustainable, and renewable, thus is viewed as promising energy carrier. However, its industrial utilization is greatly hampered by the lack of effective hydrogen storage and release method. Carbon nanotubes (CNTs) were viewed as one of the potential hydrogen containers, but it has been proved that pure CNTs cannot attain the desired target capacity of hydrogen storage. In this paper, we present a numerical study on the material-driven and structure-driven hydrogen adsorption of 3D silicon networks and propose a deformation-driven hydrogen desorption approach based on molecular simulations. Two types of 3D nanostructures, silicon nanotube-network (Si-NN) and silicon film-network (Si-FN), are first investigated in terms of hydrogen adsorption and desorption capacity with grand canonical Monte Carlo simulations. It is revealed that the hydrogen storage capacity is determined by the lithium doping ratio and geometrical parameters, and the maximum hydrogen uptake can be achieved by a 3D nanostructure with optimal configuration and doping ratio obtained through design optimization technique. For hydrogen desorption, a mechanical-deformation-driven-hydrogen-release approach is proposed. Compared with temperature/pressure change-induced hydrogen desorption method, the proposed approach is so effective that nearly complete hydrogen desorption can be achieved by Si-FN nanostructures under sufficient compression but without structural failure observed. The approach is also reversible since the mechanical deformation in Si-FN nanostructures can be elastically recovered, which suggests a good reusability. This study may shed light on the mechanism of hydrogen adsorption and desorption and thus provide useful guidance toward engineering design of microstructural hydrogen (or other gas) adsorption materials

Preparation of Mg2FeH6 Nanoparticles for Hydrogen Storage Properties

Directory of Open Access Journals (Sweden)

N. A. Niaz

2013-01-01

Full Text Available Magnesium (Mg and iron (Fe nanoparticles are prepared by thermal decomposition of bipyridyl complexes of metals. These prepared Mg-Fe (2 : 1 nanoparticles are hydrogenated under 4 MPa hydrogen pressure and 673 K for 48 hours to achieve Mg2FeH6. Their structural analysis was assessed by applying manifold techniques. The hydrogen storage properties of prepared compound were measured by Sieverts type apparatus. The desorption kinetics were measured by high pressure thermal desorption spectrometer (HP-TDS. More than 5 wt% hydrogen released was obtained by the Mg2FeH6 within 5 min, and during rehydrogenation very effective hydrogen absorption rate was observed by the compound.

Effect of oxygen on the hydrogenation properties of magnesium films

DEFF Research Database (Denmark)

Ostenfeld, Christopher Worsøe; Chorkendorff, Ib

2006-01-01

The effect of magnesium oxide on the magnesium and hydrogen desorption properties of magnesium films have been investigated. We find that by capping metallic magnesium films with oxide overlayers the apparent desorption energy of magnesium is increased from 146 kJ/mol to 314 kJ/mol. The results...... are discussed in light of previous investigations of ball-milled magnesium powders....

Temperature suppression of STM-induced desorption of hydrogen on Si(100) surfaces

DEFF Research Database (Denmark)

Thirstrup, C.; Sakurai, M.; Nakayama, T.

1999-01-01

The temperature dependence of hydrogen (H) desorption from Si(100) H-terminated surfaces by a scanning tunneling microscope (STM) is reported for negative sample bias. It is found that the STM induced H desorption rate (R) decreases several orders of magnitude when the substrate temperature...

Properties of Mg-Al alloys in relation to hydrogen storage

DEFF Research Database (Denmark)

Andreasen, A.

2005-01-01

storage e.g. in stationary applications. In this report the properties of Mg-Al alloys are reviewed in relation to solid state hydrogen storage. Alloying with Al reduces the hydrogen capacity since Al doesnot form a hydride under conventional hydriding conditions, however both the thermodynamical......Magnesium theoretically stores 7.6 wt. % hydrogen, although it requires heating to above 300 degrees C in order to release hydrogen. This limits its use for mobile application. However, due to its low price and abundance magnesium should still beconsidered as a potential candidate for hydrogen...... properties (lower desorption temperature), and kinetics of hydrogenation/dehydrogenation are improved. In addition to this, the low price of the hydride isretained along with improved heat transfer properties and improved resistance towards oxygen contamination....

Hydrogen retention properties of polycrystalline tungsten and helium irradiated tungsten

International Nuclear Information System (INIS)

Hino, T.; Koyama, K.; Yamauchi, Y.; Hirohata, Y.

1998-01-01

The hydrogen retention properties of a polycrystalline tungsten and tungsten irradiated by helium ions with an energy of 5 keV were examined by using an ECR ion irradiation apparatus and a technique of thermal desorption spectroscopy, TDS. The polycrystalline tungsten was irradiated at RT with energetic hydrogen ions, with a flux of 10 15 H cm -2 and an energy of 1.7 keV up to a fluence of 5 x 10 18 H cm -2 . Subsequently, the amount of retained hydrogen was measured by TDS. The heating temperature was increased from RT to 1000 C, and the heating rate was 50 C min -1 . Below 1000 C, two distinct hydrogen desorption peaks were observed at 200 C and 400 C. The retained amount of hydrogen was observed to be five times smaller than that of graphite, but the concentration in the implantation layer was comparable with that of graphite. Also, the polycrystalline tungsten was irradiated with 5 keV helium ions up to a fluence of 1.4 x 10 18 He cm -2 , and then re-irradiated with 1.7 keV hydrogen ions. The amount of retained hydrogen in this later experiment was close to the value in the case without prior helium ion irradiation. However, the amount of hydrogen which desorbed around the low temperature peak, 200 C, was largely enhanced. The desorption amount at 200 C saturated for the helium fluence of more than 5 x 10 17 He cm -2 . The present data shows that the trapping state of hydrogen is largely changed by the helium ion irradiation. Additionally, 5 keV helium ion irradiation was conducted on a sample pre-implanted with hydrogen ions to simulate a helium ion impact desorption of hydrogen retained in tungsten. The amount of the hydrogen was reduced as much as 50%. (orig.)

The effect of compositional changes on the structural and hydrogen storage properties of (La–Ce)Ni5 type intermetallics towards compounds suitable for metal hydride hydrogen compression

International Nuclear Information System (INIS)

Odysseos, M.; De Rango, P.; Christodoulou, C.N.; Hlil, E.K.; Steriotis, T.; Karagiorgis, G.; Charalambopoulou, G.; Papapanagiotou, T.; Ampoumogli, A.; Psycharis, V.; Koultoukis, E.; Fruchart, D.; Stubos, A.

2013-01-01

Graphical abstract: The effect of the partial substitution of La with Ce on the crystal structure and the final hydrogen storage properties of the alloys. Highlights: ► Absorption-based systems exploit the properties of reversible metal hydrides. ► AB5 intermetallics are mostly popular for thermal desorption compressors. ► Investigation of H2 absorption/desorption properties of LaNi5 and its derivatives. ► LaNi5 thermodynamic properties adjustment by partially replacing La with rare earths. -- Abstract: The present work has been aiming at the synthesis and study of a series of La 1−x Ce x Ni 5 (x = 0, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8) alloys in an attempt to investigate possible alterations of the hydrogen absorption/desorption properties The alloys were prepared by induction melting of the constituent elements. The systematic characterization of all new compounds by means of XRD and hydrogen sorption measurements revealed the effect of the partial substitution of La with Ce on the crystal structure and the final hydrogen storage properties of the alloys. Extensive absorption/desorption experiments (Van’t Hoff diagrams) have shown that such alloys can be used to build a metal hydride compressor (MHC), compressing H 2 gas from 0.2 MPa to 4.2 MPa using cold (20 °C) and hot (80 °C) water

Laser induced desorption as hydrogen retention diagnostic method

Energy Technology Data Exchange (ETDEWEB)

Zlobinski, Miroslaw

2016-07-15

Laser Induced Desorption Spectroscopy (LIDS) is a diagnostic method to measure the hydrogen content in the surface of a material exposed to a hydrogen isotope (H,D,T) plasma. It is developed mainly to monitor hydrogen retention in the walls of magnetic fusion devices that have to limit the amount of their fuel tritium mainly due to safety reasons. The development of fusion increasingly focusses on plasma-wall interactions for which in situ diagnostics like LIDS are required that work during plasma operation and without tile removal. The method has first been developed for thin amorphous hydrocarbon (a-C:H < 500 nm) layers successfully and is studied in the present work on thick (15 μm) layers, carbon fibre composites (CFCs), bulk tungsten (W), W fuzz and mixed C/W materials. In LID a 3 ms Nd:YAG (1064 nm) laser pulse heats a spot of diameter 3 mm with 500 {sup MW}/{sub m{sup 2}} on W to 1800 K at the surface and thus above 1300 K within ca. 0.2 mm depth. On C materials (graphite, CFC, a-C:H) this temperature guarantees a nearly complete (>95%) desorption already within 1.5 ms pulse duration. The retained hydrogen atoms are desorbed locally, recombine to molecules and migrate promptly to the surface via internal channels like pores and grain boundaries. Whereas, in W the retained hydrogen atoms have to diffuse through the bulk material, which is a relatively slow process also directed into the depth. The desorbed hydrogen fraction can thus be strongly reduced to 18-91% as observed here. This fraction is measured by melting the central part of a previously heated spot ca. 40 μm deep with a diameter 2 mm, 3 ms laser pulse, releasing the remaining hydrogen. W samples exposed to different plasmas in TEXTOR, Pilot-PSI, PSI-2, PADOS and PlaQ show that the desorption fraction of LID mainly decreases due to higher sample temperature during plasma exposure. The heat causes deeper hydrogen diffusion and/or stronger hydrogen trapping due to creation of traps with higher

Laser induced desorption as hydrogen retention diagnostic method

International Nuclear Information System (INIS)

Zlobinski, Miroslaw

2016-01-01

Laser Induced Desorption Spectroscopy (LIDS) is a diagnostic method to measure the hydrogen content in the surface of a material exposed to a hydrogen isotope (H,D,T) plasma. It is developed mainly to monitor hydrogen retention in the walls of magnetic fusion devices that have to limit the amount of their fuel tritium mainly due to safety reasons. The development of fusion increasingly focusses on plasma-wall interactions for which in situ diagnostics like LIDS are required that work during plasma operation and without tile removal. The method has first been developed for thin amorphous hydrocarbon (a-C:H < 500 nm) layers successfully and is studied in the present work on thick (15 μm) layers, carbon fibre composites (CFCs), bulk tungsten (W), W fuzz and mixed C/W materials. In LID a 3 ms Nd:YAG (1064 nm) laser pulse heats a spot of diameter 3 mm with 500 MW / m 2 on W to 1800 K at the surface and thus above 1300 K within ca. 0.2 mm depth. On C materials (graphite, CFC, a-C:H) this temperature guarantees a nearly complete (>95%) desorption already within 1.5 ms pulse duration. The retained hydrogen atoms are desorbed locally, recombine to molecules and migrate promptly to the surface via internal channels like pores and grain boundaries. Whereas, in W the retained hydrogen atoms have to diffuse through the bulk material, which is a relatively slow process also directed into the depth. The desorbed hydrogen fraction can thus be strongly reduced to 18-91% as observed here. This fraction is measured by melting the central part of a previously heated spot ca. 40 μm deep with a diameter 2 mm, 3 ms laser pulse, releasing the remaining hydrogen. W samples exposed to different plasmas in TEXTOR, Pilot-PSI, PSI-2, PADOS and PlaQ show that the desorption fraction of LID mainly decreases due to higher sample temperature during plasma exposure. The heat causes deeper hydrogen diffusion and/or stronger hydrogen trapping due to creation of traps with higher binding energy

Reactive Desorption of CO Hydrogenation Products under Cold Pre-stellar Core Conditions

Science.gov (United States)

Chuang, K.-J.; Fedoseev, G.; Qasim, D.; Ioppolo, S.; van Dishoeck, E. F.; Linnartz, H.

2018-02-01

The astronomical gas-phase detection of simple species and small organic molecules in cold pre-stellar cores, with abundances as high as ∼10‑8–10‑9 n H, contradicts the generally accepted idea that at 10 K, such species should be fully frozen out on grain surfaces. A physical or chemical mechanism that results in a net transfer from solid-state species into the gas phase offers a possible explanation. Reactive desorption, i.e., desorption following the exothermic formation of a species, is one of the options that has been proposed. In astronomical models, the fraction of molecules desorbed through this process is handled as a free parameter, as experimental studies quantifying the impact of exothermicity on desorption efficiencies are largely lacking. In this work, we present a detailed laboratory study with the goal of deriving an upper limit for the reactive desorption efficiency of species involved in the CO–H2CO–CH3OH solid-state hydrogenation reaction chain. The limit for the overall reactive desorption fraction is derived by precisely investigating the solid-state elemental carbon budget, using reflection absorption infrared spectroscopy and the calibrated solid-state band-strength values for CO, H2CO and CH3OH. We find that for temperatures in the range of 10 to 14 K, an upper limit of 0.24 ± 0.02 for the overall elemental carbon loss upon CO conversion into CH3OH. This corresponds with an effective reaction desorption fraction of ≤0.07 per hydrogenation step, or ≤0.02 per H-atom induced reaction, assuming that H-atom addition and abstraction reactions equally contribute to the overall reactive desorption fraction along the hydrogenation sequence. The astronomical relevance of this finding is discussed.

Properties of MgAl alloys in relation to hydrogen storage

Energy Technology Data Exchange (ETDEWEB)

Andreasen, Anders

2005-08-01

Magnesium theoretically stores 7.6 wt. % hydrogen, although it requires heating to above 300 degrees C in order to release hydrogen. This limits its use for mobile application. However, due to its low price and abundance magnesium should still be considered as a potential candidate for hydrogen storage e.g. in stationary applications. In this report the properties of Mg-Al alloys are reviewed in relation to solid state hydrogen storage Alloying with Al reduces the hydrogen capacity since Al does not form a hydride under conventional hydriding conditions, however both the thermodynamical properties (lower desorption temperature), and kinetics of hydrogenation/dehydrogenation are improved. In addition to this, the low price of the hydride is retained along with improved heat transfer properties and improved resistance towards oxygen contamination. (au)

Analysis of the technique Thermal Desorption Spectroscopy (TDS) and its Application for the Characterization of Metal -Hydrogen Systems

International Nuclear Information System (INIS)

Castro, F.J.

2000-01-01

limiting step is the recombination of two hydrogen atoms on the surface of the material. When the surface of the sample is in the a phase (solid solution) the rate limiting step is one of the processes that occurs on the surface of the material: the transfer of a hydrogen atom from the bulk to the surface or the recombination and desorption on the surface. By fitting the spectra we obtain an activation energy equal to 31 n 6 kJ/mol for the b phase, and equal to 35 n 3 kJ/mol for the a phase. We also compare the spectra of the powder with the spectra of the granules, foils and wires. Based on this comparison we analyze the effect on the desorption spectra of the characteristic size and geometry of the samples.Finally, we present a study of hydrogen desorption in the Pd-H system poisoned with sulfur. The poisoning produces as main effects a delay of the absorption and desorption processes without any appreciable loss in the storage capacity of the material.The experimental apparatus and theoretical models developed have been applied to the study of a MH system using samples with different morphology, characteristic size, geometry and surface state. The spectra were measured for different hydrogen concentrations and heating speeds. The results obtained encourage the utilization of TDS for the study and characterization of hydrogen desorption in MH systems. The technique is suited for the detailed analysis of the physical properties of the system and for the qualitative evaluation of the kinetic processes and their possible influence on technological devices

Hydriding properties of an Mg-Al-Ni-Nd hydrogen storage alloy

International Nuclear Information System (INIS)

Duarte, G.I.; Bustamante, L.A.C.; Miranda, P.E.V. de

2007-01-01

This work presents the development of an Mg-Al-Ni-Nd alloy for hydrogen storage purposes. The hydrogen storage properties of the alloy were analyzed using pressure-composition isotherms and hydrogen desorption kinetic curves at different temperatures. The characterization of the microstructures, before and after hydrogenation, was performed using X-ray diffraction, scanning electron microscopy and energy-dispersive spectrometry. Hydrogenation caused significant changes in the alloy microstructure. Two pressure plateaus were observed. The maximum hydrogen storage reversible capacity measured was 4 wt.% at 573 K

Development of a kinetic model of hydrogen absorption and desorption in magnesium and analysis of the rate-determining step

Science.gov (United States)

Kitagawa, Yuta; Tanabe, Katsuaki

2018-05-01

Mg is promising as a new light-weight and low-cost hydrogen-storage material. We construct a numerical model to represent the hydrogen dynamics on Mg, comprising dissociative adsorption, desorption, bulk diffusion, and chemical reaction. Our calculation shows a good agreement with experimental data for hydrogen absorption and desorption on Mg. Our model clarifies the evolution of the rate-determining processes as absorption and desorption proceed. Furthermore, we investigate the optimal condition and materials design for efficient hydrogen storage in Mg. By properly understanding the rate-determining processes using our model, one can determine the design principle for high-performance hydrogen-storage systems.

High stability of palladium/kieselguhr composites during absorption/desorption cycling for hydrogen isotope separation

Energy Technology Data Exchange (ETDEWEB)

Lei, Yang, E-mail: lei.y@outlook.com; Liu, Xiaopeng; Li, Shuo; Jiang, Lijun; Zhang, Chao; Li, Shuai; He, Di; Wang, Shumao

2016-12-15

Highlights: • Pd/K composites with as high as 57 wt.% of Pd have been successfully prepared. • Palladium particles can be effectively packed into the pores of kieselguhr substrates. • Variation of heat-treatment temperatures hardly affect hydrogen absorption capacity and hydrogen saturation time of the Pd/K. • Anti-pulverization property of Pd/K can be improved by packing palladium into the kieselguhr internal pores and heating at 1300 °C. - Abstract: Palladium/kieselguhr (Pd/K) composites with 57 wt.% of Pd were prepared by an improved dipping and thermal decomposition method and heated at elevated temperature to reduce breakdown during hydrogenation-dehydrogenation cycles. The hydrogen absorption kinetic properties of the samples heated at different temperatures were tested under the condition of 20 °C with 100 kPa hydrogen pressure. The 1300 °C heated Pd/K composites were repeated up to 4010 absorption and desorption cycles at temperature ranges between −40 °C and 200 °C. The results show that the phase structure, hydrogen absorption capacity and hydrogen saturation time of the Pd/K were not affected by the change of heat-treated temperatures. And after heat treatment at 1300 °C, the Pd/K particles were strengthened and fraction of larger than 80 mesh were as high as 93.4%.

Study of the chemisorption and hydrogenation of propylene on platinum by temperature-programed desorption

Energy Technology Data Exchange (ETDEWEB)

Tsuchiya, S.; Nakamura, M.; Yoshioka, N.

1978-01-01

Temperature-programed desorption (TPD) chromotograms of propylene adsorbed on platinum black in the absence or presence of hydrogen preadsorbed, admitted simultaneously, or admitted later, all showed four peaks at about 260/sup 0/ (A), 380/sup 0/ (B), 570/sup 0/ (C), and higher than 720/sup 0/K (D). Peaks A and B were identified as mixtures of propylene and propane, and peaks C and D were methane formed by thermal decomposition of the chemisorbed propylene during desorption. When nitrogen rather than helium was used as the carrier gas for the TPD, only delta-hydrogen was observed; this suggested that propylene was more strongly adsorbed on the platinum than hydrogen. Studies of the reactivities with propylene of the various types of chemisorbed hydrogen previously detected by TPD showed that propylene reacted with ..gamma..-hydrogen present on the surface in the form of hydrogen atoms chemisorbed on top of platinum atoms and with ..beta..-hydrogen, molecular hydrogen chemisorbed in a bridged form, but did not react with delta-hydrogen. Tables and graph.

Effect of multi-wall carbon nanotubes supported nano-nickel and TiF{sub 3} addition on hydrogen storage properties of magnesium hydride

Energy Technology Data Exchange (ETDEWEB)

Su, Wei; Zhu, Yunfeng, E-mail: yfzhu@njtech.edu.cn; Zhang, Jiguang; Liu, Yana; Yang, Yang; Mao, Qifeng; Li, Liquan

2016-06-05

Multi-wall carbon nanotubes supported nano-nickel (Ni/MWCNTs) with superior catalytic effects was introduced to magnesium hydride by the process of hydriding combustion synthesis (HCS) and mechanical milling (MM). The effect of different Ni/MWCNTs contents (5 wt.%, 10 wt.%, 15 wt.%, 20 wt.%) on the hydrogenation and dehydrogenation properties of the composite was investigated systematically. It is revealed that Mg{sub 85}-(Ni/MWCNTs){sub 15} composite shows the best comprehensive hydrogen storage properties, which absorbs 5.68 wt.% hydrogen within 100 s at 373 K and releases 4.31 wt.% hydrogen within 1800 s at 523 K under initial hydrogen pressures of 3.0 and 0.005 MPa, respectively. The in situ formed nano-Mg{sub 2}Ni and MWCNTs have excellent catalytic effect on the hydrogenation and dehydrogenation performances of MgH{sub 2}. To further improve the hydrogen absorption/desorption properties, TiF{sub 3} was added to the Mg–Ni/MWCNTs system. The result shows that TiF{sub 3} addition has little influence on the thermodynamic performance, but affects greatly the kinetic properties. The Mg{sub 85}-(Ni/MWCNTs){sub 15}-TiF{sub 3} composite exhibits an appreciably enhanced hydrogen desorption performance at low temperature, and the hydrogen desorption capacity within 1800 s at 473 K for the TiF{sub 3}-added composite is approximately four times the capacity of Mg{sub 85}-(Ni/MWCNTs){sub 15} under the same condition. The catalytic effects during hydrogenation and dehydrogenation have been discussed in the study. - Highlights: • The nanosized Ni/MWCNTs catalyst was successfully prepared. • Ni/MWCNTs shows superior catalytic effect on H absorption/desorption of Mg. • Mg{sub 85}-(Ni/MWCNTs){sub 15} composite shows the best hydrogen storage properties. • Ni/MWCNTs coupling with TiF{sub 3} improves the hydriding/dehydriding properties largely.

Searching out the hydrogen absorption/desorption limiting reaction factors: Strategies allowing to increase kinetics

Energy Technology Data Exchange (ETDEWEB)

Zeaiter, Ali, E-mail: ali.zeaiter@femto-st.fr; Chapelle, David; Nardin, Philippe

2015-10-05

Highlights: • A macro scale thermodynamic model that simulates the response of a FeTi-X hydride tank is performed, and validated experimentally. • A sensibility study to identify the most influent input variables that can changes very largely the reaction rate. - Abstract: Hydrogen gas has become one of the most promising energy carriers. Main breakthrough concerns hydrogen solid storage, specially based on intermetallic material use. Regarding the raw material abundance and cost, the AB type alloy FeTi is an auspicious candidate to store hydrogen. Its absorption/desorption kinetics is a basic hindrance to common use, compared with more usual hydrides. First, discussions based on literature help us identifying the successive steps leading to metal hydriding, and allow to introduce the physical parameters which drive or limit the reaction. This analysis leads us to suggest strategies in order to increase absorption/desorption kinetics. Attention is then paid to a thermofluidodynamic model, allowing to describe a macroscopic solid storage reactor. Thus, we can achieve a simulation which describes the overall reaction inside the hydrogen reactor and, by varying the sub-mentioned parameters (thermal conductivity, the powder granularity, environment heat exchange…), we attempt to hierarchy the reaction limiting factors. These simulations are correlated to absorption/desorption experiments for which pressure, temperature and hydrogen flow are recorded.

A study on metal organic framework (MOF-177) synthesis, characterization and hydrogen adsorption -desorption cycles

Energy Technology Data Exchange (ETDEWEB)

Viditha, V.; Venkateswer Rao, M.; Srilatha, K.; Himabindu, V. [Centre for Environment, Institute of Science and Technology, Jawaharlal Nehru Technological University Hyderabad, Kukatpally, Hyderabad-500 085, A.P. (India); Yerramilli, Anjaneyulu [Director, TLGVRC, JSU Box 18739, JSU, Jackson, MS 32917-0939 (United States)

2013-07-01

Hydrogen has long been considered to be an ideal alternative to fossil-fuel systems and much work has now been done on its storage. There are four main methods of hydrogen storage: as a liquid; as compressed hydrogen; in the form of metal hydrides; and by physisorption. Among all the materials metal organic frameworks (MOFs) are considered to have desirable properties like high porosity, pore volume and high thermal stability. MOF-177 is considered to be an ideal storage material. In this paper we study about its synthesis and hydrogen storage capacities of MOF-177 at different pressures ranging from 25, 50, 75 and 100 bar respectively. The obtained samples are characterized by XRD, BET and SEM. The recorded results show that the obtained hydrogen capacity is 1.1, 2.20, 2.4 and 2.80 wt%. The desorption capacity is 0.9, 2.1, 2.37 and 2.7 wt% at certain temperatures like 373 K.

Hydrogenation properties and microstructure of Ti-Mn-based alloys for hybrid hydrogen storage vessel

International Nuclear Information System (INIS)

Shibuya, Masachika; Nakamura, Jin; Akiba, Etsuo

2008-01-01

Ti-Mn-based AB 2 -type alloys which are suitable for a hybrid hydrogen storage vessel have been synthesized and evaluated hydrogenation properties. As the third element V was added to Ti-Mn binary alloys. All the alloys synthesized in this work mainly consist of the C14 Laves and BCC phase. In the case of Ti0.5V0.5Mn alloy, the amounts of hydrogen absorption was 1.8 wt.% at 243 K under the atmosphere of 7 MPa H 2 , and the hydrogen desorption pressure was in the range of 0.2-0.4 MPa at 243 K. The hydrogen capacity of this alloy did not saturate under 7 MPa H 2 and seems to increase with hydrogen pressure up to 35 MPa that is estimated working pressure of the hybrid hydrogen storage vessel

Effect of hydrogenation disproportionation conditions on magnetic anisotropy in Nd-Fe-B powder prepared by dynamic hydrogenation disproportionation desorption recombination

Directory of Open Access Journals (Sweden)

Masao Yamazaki

2017-05-01

Full Text Available Various anisotropic Nd-Fe-B magnetic powders were prepared by the dynamic hydrogenation disproportionation desorption recombination (d-HDDR treatment with different hydrogenation disproportionation (HD times (tHD. The resulting magnetic properties and microstructural changes were investigated. The magnetic anisotropy was decreased with increasing tHD. In the d-HDDR powders with higher magnetic anisotropy, fine (200–600 nm and coarse (600–1200 nm Nd2Fe14B grains were observed. The coarse Nd2Fe14B grains showed highly crystallographic alignment of the c-axis than fine Nd2Fe14B grains. In the highly anisotropic Nd2Fe14B d-HDDR powder, a large area fraction of lamellar-like structures consisting of NdH2 and α-Fe were observed after HD treatment. Furthermore, the mean diameter of the lamellar-like regions, where lamellar-like structures orientate to the same direction in the HD-treated alloys was close to that of coarse Nd2Fe14B grains after d-HDDR treatment. Thus, the lamellar-like regions were converted into the crystallographically aligned coarse Nd2Fe14B grains during desorption recombination treatment, and magnetic anisotropy is closely related to the volume fraction of lamellar-like regions observed after HD treatment.

Thermal desorption of hydrogen from Mg2Ni hydrogen storage materials.

Science.gov (United States)

Hur, Tae Hong; Han, Jeong Seb; Kim, Jin Ho; Kim, Byung Kwan

2011-07-01

In order to investigate the influence of HCS on the hydrogen occupation site of Mg2Ni alloy, the thermal desorption technique has been applied to Mg2Ni hydride made by hydriding combustion synthesis (HCS). Mg2Ni was made under low temperature in a short time by the HCS compared to conventional melting process. At various initial hydride wt% from 0.91 to 3.52, the sample was heated to 623 K at a rate of 1.0 K/min. The starting temperature of the evolution of hydrogen goes higher as the initial hydride wt% increases. Only one peak is shown in the case of the small initial hydride wt%. But two peaks appeared with increasing initial hydride wt%. The activation energies obtained by the first and second peaks are 113.0 and 99.5 kJ/mol respectively. The two site occupation model by Darriet et al. was proved. The influence of HCS on the hydrogen occupation site of Mg2Ni alloy is nonexistent.

Adsorption and desorption of hydrogen and carbon monoxide were studied on alumina-supported iridium catalysts

Energy Technology Data Exchange (ETDEWEB)

Etherton, B.P.

1980-01-01

The adsorption and desorption of hydrogen and carbon monoxide were studied on alumina-supported iridium catalysts which were examined by a scanning transmission electron microscope (STEM). The metal particle size and number of particles per area of catalyst increased with increasing metal loading. The particles were approx. 10 A. in diameter, cubo-octahedral shaped, and approx. 80-90% disperse. The STEM electron beam caused negligible damage to the samples. Hydrogen adsorption measurements showed that the hydrogen-iridium atom ratio was 1.2:1-1.3:1 and increased with decreasing metal loading. Temperature-programed desorption showed four types of adsorbed hydrogen desorbing at -90/sup 0/C (I), 15/sup 0/C (IV), 115/sup 0/C (II), and 245/sup 0/C (III). Types II and IV desorb from single atom sites and Types I and III from multiple atom sites. Type I is in rapid equilibrium with the gas phase. All desorption processes appear to be first order. Carbon monoxide adsorbed nondissociatively at 25/sup 0/C with approx. 0.7:1 CO/Ir atom ratio. It adsorbed primarily in linear forms at low coverage, but a bridged form appeared at high coverage.

Desorption process of hydrogen starting from the Mg2NiH4 and Mg2NiH0.3

International Nuclear Information System (INIS)

Iturbe G, J.L.; Basurto S, R.; Lopez M, B.E.

2002-01-01

In this work the desorption velocity of H 2 was determined starting from the magnesium nickel hydride once the reaction between the intermetallic and the hydrogen was realized, the compound were analysed by means of a thermogravimetric equipment, the conditions for carrying out the analysis were: 10 C by minute in nitrogen atmosphere at a volume of 50 ml by minute, subsequently the isotherms at different times were programmed and the desorption velocity of hydrogen was determined. The results show that the desorption velocity of hydrogen depends of the temperature, using only the nitrogen flux which acts as a carrier gas. Observing that the hydrogen liberation is carried out by means of two mechanisms according to the isotherms obtained. (Author)

Preparation and Hydrogen Absorption/Desorption of Nanoporous Palladium Thin Films

Directory of Open Access Journals (Sweden)

Wen-Chung Li

2009-12-01

Full Text Available Nanoporous Pd (np-Pd was prepared by co-sputtering Pd-Ni alloy films onto Si substrates, followed by chemical dealloying with sulfuric acid. X-ray diffractometry and chemical analysis were used to track the extent of dealloying. The np-Pd structure was changed from particle-like to sponge-like by diluting the sulfuric acid etchant. Using suitable precursor alloy composition and dealloying conditions, np-Pd films were prepared with uniform and open sponge-like structures, with interconnected ligaments and no cracks, yielding a large amount of surface area for reactions with hydrogen. Np-Pd films exhibited shorter response time for hydrogen absorption/desorption than dense Pd films, showing promise for hydrogen sensing.

Measurement of hydrogen solubility and desorption rate in V-4Cr-4Ti and liquid lithium-calcium alloys

Energy Technology Data Exchange (ETDEWEB)

Park, J.H.; Erck, R.; Park, E.T. [Argonne National Lab., IL (United States)] [and others

1997-04-01

Hydrogen solubility in V-4Cr-4Ti and liquid lithium-calcium was measured at a hydrogen pressure of 9.09 x 10{sup {minus}4} torr at temperatures between 250 and 700{degrees}C. Hydrogen solubility in V-4Cr-4Ti and liquid lithium decreased with temperature. The measured desorption rate of hydrogen in V-4Cr-4Ti is a thermally activated process; the activation energy is 0.067 eV. Oxygen-charged V-4Cr-4Ti specimens were also investigated to determine the effect of oxygen impurity on hydrogen solubility and desorption in the alloy. Oxygen in V-4Cr-4Ti increases hydrogen solubility and desorption kinetics. To determine the effect of a calcium oxide insulator coating on V-4Cr-4Ti, hydrogen solubility in lithium-calcium alloys that contained 0-8.0 percent calcium was also measured. The distribution ratio R of hydrogen between liquid lithium or lithium-calcium and V-4Cr-4Ti increased as temperature decreased (R {approx} 10 and 100 at 700 and 250{degrees}C, respectively). However at <267{degrees}C, solubility data could not be obtained by this method because of the slow kinetics of hydrogen permeation through the vanadium alloy.

Measurement of hydrogen solubility and desorption rate in V-4Cr-4Ti and liquid lithium-calcium alloys

International Nuclear Information System (INIS)

Park, J.H.; Erck, R.; Park, E.T.

1997-01-01

Hydrogen solubility in V-4Cr-4Ti and liquid lithium-calcium was measured at a hydrogen pressure of 9.09 x 10 -4 torr at temperatures between 250 and 700 degrees C. Hydrogen solubility in V-4Cr-4Ti and liquid lithium decreased with temperature. The measured desorption rate of hydrogen in V-4Cr-4Ti is a thermally activated process; the activation energy is 0.067 eV. Oxygen-charged V-4Cr-4Ti specimens were also investigated to determine the effect of oxygen impurity on hydrogen solubility and desorption in the alloy. Oxygen in V-4Cr-4Ti increases hydrogen solubility and desorption kinetics. To determine the effect of a calcium oxide insulator coating on V-4Cr-4Ti, hydrogen solubility in lithium-calcium alloys that contained 0-8.0 percent calcium was also measured. The distribution ratio R of hydrogen between liquid lithium or lithium-calcium and V-4Cr-4Ti increased as temperature decreased (R ∼ 10 and 100 at 700 and 250 degrees C, respectively). However at <267 degrees C, solubility data could not be obtained by this method because of the slow kinetics of hydrogen permeation through the vanadium alloy

Improved hydrogen absorption and desorption kinetics of magnesium-based alloy via addition of yttrium

Science.gov (United States)

Yang, Tai; Li, Qiang; Liu, Ning; Liang, Chunyong; Yin, Fuxing; Zhang, Yanghuan

2018-02-01

Yttrium (Y) is selected to modify the microstructure of magnesium (Mg) to improve the hydrogen storage performance. Thereby, binary alloys with the nominal compositions of Mg24Yx (x = 1-5) are fabricated by inexpensive casting technique. Their microstructure and phase transformation during hydriding and dehydriding process are characterized by using X-ray diffraction, scanning electron microscopy, and high-resolution transmission electron microscopy analysis. The isothermal hydrogen absorption and desorption kinetics are also measured by a Sievert's-type apparatus at various temperatures. Typical multiphase structures of binary alloy can be clearly observed. All of these alloys can reversibly absorb and desorb large amount of hydrogen at proper temperatures. The addition of Y markedly promotes the hydrogen absorption kinetics. However, it results in a reduction of reversible hydrogen storage capacity. A maximum value of dehydrogenation rate is observed with the increase of Y content. The Mg24Y3 alloy has the optimal desorption kinetic performance, and it can desorb about 5.4 wt% of hydrogen at 380 °C within 12 min. Combining Johnson-Mehl-Avrami kinetic model and Arrhenius equation, the dehydrogenation activation energy of the alloys are evaluated. The Mg24Y3 alloy also has the lowest dehydrogenation activation energy (119 kJ mol-1).

Adsorption and temperature-programmed desorption of hydrogen with dispersed platinum and platinum-gold catalysts

Energy Technology Data Exchange (ETDEWEB)

Anderson, J.R.; Foger, K.; Breakspere, R.J.

1979-05-01

Adsorption and temperature-programmed desorption of hydrogen with dispersed platinum and platinum-gold catalysts was studied with 0.9-3Vertical Bar3< platinum on silica gel, aerosil, sodium and lanthanum Y zeolites, and ..gamma..-alumina, and on aerosil-supported gold-platinum alloys containing 2, 10, 24, 33, and 85Vertical Bar3< gold. Surface enrichment with gold in the alloy systems, as derived from hydrogen adsorption data and predicted from surface enrichment theory and electron microscopic measurements of particle size, were in good agreement, which indicated that equilibrium was achieved by the thermal treatment (oxygen at 573/sup 0/K, hydrogen at 620/sup 0/K, repeated cycles) used. Hydrogen spillover to gold was observed at the higher hydrogen pressures tested on the alloys with high gold content, and to the zeolite supports. The temperature-programed desorption profiles were independent of gold content, which indicated that gold acts only as diluent, and that isolated surface platinum atoms become populated with hydrogen atoms either by hydrogen atom spillover from platinum ensembles to gold and from the gold to the isolated platinum, and/or by adsorption of a molecule directly on the isolated platinum and chemisorption of one H atom at an adjacent gold atom. The distribution of surface platinum ensembles was evaluated by a computer simulation method.

Studies of hydrogen absorption and desorption processes in advanced intermetallic hydrides

Energy Technology Data Exchange (ETDEWEB)

Sato, Masashi

2005-07-01

This work is a part of the research program performed in the Department of Energy Systems, Institute for Energy Technology (Kjeller, Norway), which is focused on the development of the advanced hydrogen storage materials. The activities are aimed on studies of the mechanisms of hydrogen interactions with intermetallic alloys with focus on establishing an interrelation between the crystal structure, thermodynamics and kinetics of the processes in the metal-hydrogen systems, on the one hand, and hydrogen storage properties (capacity, rates of desorption, hysteresis). Many of the materials under investigation have potential to be applied in applications, whereas some already have been commercialised in the world market. A number of metals take up considerable amounts of hydrogen and form chemical compounds with H, metal hydrides. Unfortunately, binary hydrides are either very stable (e.g. for the rare earth metals [RE], Zr, Ti, Mg: metal R) or are formed at very high applied pressures of hydrogen gas (e.g. for the transition metals, Ni, Co, Fe, etc.: Metal T). However, hydrogenation process becomes easily reversible at very convenient from practical point of view conditions, around room temperature and at H2 pressures below 1 MPa for the two-component intermetallic alloys R{sub x}T{sub y}. This raised and maintains further interest to the intermetallic hydrides as solid H storage materials. Materials science research of this thesis is focused on studies of the reasons staying behind the beneficial effect of two non-transition elements M(i.e., In and Sn) contributing to the formation of the ternary intermetallic alloys R{sub x}T{sub y}M{sub 2}., on the hydrogen storage behaviours. Particular focus is on two aspects where the remarkable improvement of ordinary metal hydrides is achieved via introduction of In and Sn: a) Increase of the volume density of stored hydrogen in solid materials to the record high level. b) Improvement of the kinetics of hydrogen charge and

Effects of hydrogen adsorption on the properties of double wall BN and (BN){sub x}C{sub y} nanotubes

Energy Technology Data Exchange (ETDEWEB)

Freitas, A. [Departamento de Física, Universidade Federal da Paraíba, Caixa Postal 5008, 58059-900 João Pessoa, PB (Brazil); Azevedo, S., E-mail: sazevedo@fisica.ufpb.br [Departamento de Física, Universidade Federal da Paraíba, Caixa Postal 5008, 58059-900 João Pessoa, PB (Brazil); Kaschny, J.R. [Instituto Federal da Bahia – Campus Vitoria da Conquista, Avenida Amazonas 3150, 45030-220 Vitória da Conquista, BA (Brazil)

2016-01-15

In the present contribution, we apply first-principles calculations, based on the density functional theory, to study the effects of hydrogen adsorption on the structural and electronic properties of boron nitride and hybrid carbon–boron nitride double wall nanotubes. The results demonstrate that the hydrogen decoration induces significant structural deformation and an appreciable reduction in the gap energy. When the number of hydrogen atoms introduced on the outer wall is increased, desorption of hydrogen pairs are observed. The calculations indicate that each adsorbed hydrogen atom induces a structural deformation with an energetic cost of about 68 meV/atom. It is also found that the introduction of hydrogen atoms can be applied as an efficient tool for tuning the electronic properties of such structures. - Graphical abstract: Localized density of states of a hydrogenated double wall boron nitride nanotube. Some hydrogen pairs are desorbed, forming H{sub 2} molecules. - Highlights: • Hydrogenation induces structural deformation and reduction in the gap energy. • Each H atom induces a deformation with an energetic cost of about 68 meV/atom. • In some cases, desorption of H pairs from the outer wall is observed.

Hydrogen storage and hydrolysis properties of core-shell structured Mg-MFx (M=V, Ni, La and Ce) nano-composites prepared by arc plasma method

Science.gov (United States)

Mao, Jianfeng; Zou, Jianxin; Lu, Chong; Zeng, Xiaoqin; Ding, Wenjiang

2017-10-01

In this work, core-shell structured Mg-MFx (M = V, Ni, La and Ce) nano-composites are prepared by using arc plasma method. The particle size distribution, phase components, microstructures, hydrogen sorption properties of these composites and hydrolysis properties of their corresponding hydrogenated powders are carefully investigated. It is shown that the addition of MFx through arc plasma method can improve both the hydrogen absorption kinetics of Mg and the hydrolysis properties of corresponding hydrogenated powders. Among them, the Mg-NiF2 composite shows the best hydrogen absorption properties at relatively low temperatures, which can absorb 3.26 wt% of H2 at 373 K in 2 h. Such rapid hydrogen absorption rate is mainly due to the formation of Mg2Ni and MgF2 on Mg particles during arc evaporation and condensation. In contrast, measurements also show that the hydrogenated Mg-VF3 composite has the lowest peak desorption temperature and the fastest hydrolysis rate among all the hydrogenated Mg-MFx composites. The less agglomeration tendency of Mg particles and VO2 covered on MgH2 particles account for the reduced hydrogen desorption temperature and enhanced hydrolysis rate.

The kinetics of hydrogen absorption/desorption within nanostructured composite Ni79.1Co18.6Cu2.3 alloy using resistometry

International Nuclear Information System (INIS)

Spasojević, M.; Maričić, A.; Ribić Zelenović, L.; Krstajić, N.; Spasojević, P.

2013-01-01

Highlights: ► Nanostructured Ni 79.1 Co 18.6 Cu 2.3 powder was obtained by electrochemical deposition. ► Correlation observed between electrical conductivity and absorbed hydrogen amount. ► Hydrogen absorption/desorption mechanism was determined. - Abstract: Ni 79.1 Co 18.6 Cu 2.3 powder was obtained by electrochemical deposition from an ammonium sulfate bath. The structure and surface morphology of the powder were detected by X-ray diffraction (XRD) and scanning electron microscopy (SEM), respectively. The electrochemically obtained Ni 79.1 Co 18.6 Cu 2.3 alloy contained an amorphous phase and nanocrystals with an average size of 6.8 nm of FCC phase of the solid solution of cobalt and copper in nickel. Nanocrystals were characterized by a high average microstrain value and high minimum density of chaotically distributed dislocations. X-ray analysis also showed that powder hydrogenation at an elevated temperature of up to 200 °C did not change unit cell parameters and mean crystallite size value. SEM images show the formation of two shapes of powder particles: large cauliflower-like particles and small dendritic ones. Powder pressing at 10 MPa and at 25 °C gave samples that were analyzed for hydrogen absorption/desorption within the temperature range of 160–200 °C. Changes in electrical resistivity during absorption/desorption were monitored. The reciprocal value of resistivity (electrical conductivity) was found to increase linearly with increasing amount of absorbed hydrogen. The experimental results were used to propose an absorption/desorption mechanism. The adsorbed hydrogen molecule dissociates on alloy surface, forming adsorbed atoms. Adatoms penetrate and diffuse into the bulk of the alloy, simultaneously donating their electrons to the conduction band of the alloy. The increase in the concentration of free electrons induces a decrease in electrical resistivity. The overall absorption rate during initial absorption is determined by the

Effects of Molybdenum Addition on Hydrogen Desorption of TiC Precipitation-Hardened Steel

Science.gov (United States)

Song, Eun Ju; Baek, Seung-Wook; Nahm, Seung Hoon; Suh, Dong-Woo

2018-03-01

The hydrogen-trap states in TiC and MoC that have coherent interfaces with ferrite were investigated using first-principles calculation. The trapping sites of TiC were the interfaces and interstitial sites of ferrite. On the other hand, the trapping sites of MoC were ferrite interstitial sites; the interface had a negative binding energy with H. Thermal desorption analysis confirms that the amounts of diffusible hydrogen were significantly reduced by addition of Mo in Ti-bearing steel.

Statistical physics modeling of hydrogen desorption from LaNi{sub 4.75}Fe{sub 0.25}: Stereographic and energetic interpretations

Energy Technology Data Exchange (ETDEWEB)

Wjihi, Sarra [Unité de Recherche de Physique Quantique, 11 ES 54, Faculté des Science de Monastir (Tunisia); Dhaou, Houcine [Laboratoire des Etudes des Systèmes Thermiques et Energétiques (LESTE), ENIM, Route de Kairouan, 5019 Monastir (Tunisia); Yahia, Manel Ben; Knani, Salah [Unité de Recherche de Physique Quantique, 11 ES 54, Faculté des Science de Monastir (Tunisia); Jemni, Abdelmajid [Laboratoire des Etudes des Systèmes Thermiques et Energétiques (LESTE), ENIM, Route de Kairouan, 5019 Monastir (Tunisia); Lamine, Abdelmottaleb Ben, E-mail: abdelmottaleb.benlamine@gmail.com [Unité de Recherche de Physique Quantique, 11 ES 54, Faculté des Science de Monastir (Tunisia)

2015-12-15

Statistical physics treatment is used to study the desorption of hydrogen on LaNi{sub 4.75}Fe{sub 0.25}, in order to obtain new physicochemical interpretations at the molecular level. Experimental desorption isotherms of hydrogen on LaNi{sub 4.75}Fe{sub 0.25} are fitted at three temperatures (293 K, 303 K and 313 K), using a monolayer desorption model. Six parameters of the model are fitted, namely the number of molecules per site n{sub α} and n{sub β}, the receptor site densities N{sub αM} and N{sub βM}, and the energetic parameters P{sub α} and P{sub β}. The behaviors of these parameters are discussed in relationship with desorption process. A dynamic study of the α and β phases in the desorption process was then carried out. Finally, the different thermodynamical potential functions are derived by statistical physics calculations from our adopted model.

Hydrogen spillover phenomenon: Enhanced reversible hydrogen adsorption/desorption at Ta{sub 2}O{sub 5}-coated Pt electrode in acidic media

Energy Technology Data Exchange (ETDEWEB)

Sata, Shunsuke [Department of Electronic Chemistry, Interdisciplinary Graduate School of Science and Engineering, Tokyo Institute of Technology, 4259-G1-5 Nagatsuta, Midori-ku, Yokohama 226-8502 (Japan); Awad, Mohamed I.; El-Deab, Mohamed S. [Department of Electronic Chemistry, Interdisciplinary Graduate School of Science and Engineering, Tokyo Institute of Technology, 4259-G1-5 Nagatsuta, Midori-ku, Yokohama 226-8502 (Japan); Department of Chemistry, Faculty of Science, Cairo University, Cairo (Egypt); Okajima, Takeyoshi [Department of Electronic Chemistry, Interdisciplinary Graduate School of Science and Engineering, Tokyo Institute of Technology, 4259-G1-5 Nagatsuta, Midori-ku, Yokohama 226-8502 (Japan); Ohsaka, Takeo, E-mail: ohsaka@echem.titech.ac.j [Department of Electronic Chemistry, Interdisciplinary Graduate School of Science and Engineering, Tokyo Institute of Technology, 4259-G1-5 Nagatsuta, Midori-ku, Yokohama 226-8502 (Japan)

2010-04-01

The current study is concerned with the preparation and characterization of tantalum oxide-loaded Pt (TaO{sub x}/Pt) electrodes for hydrogen spillover application. XPS, SEM, EDX and XRD techniques are used to characterize the TaO{sub x}/Pt surfaces. TaO{sub x}/Pt electrodes were prepared by galvanostatic electrodeposition of Ta on Pt from LiF-NaF (60:40 mol%) molten salts containing K{sub 2}TaF{sub 7} (20 wt%) at 800 deg. C and then by annealing in air at various temperatures (200, 400 and 600 deg. C). The thus-fabricated TaO{sub x}/Pt electrodes were compared with the non-annealed Ta/Pt and the unmodified Pt electrodes for the hydrogen adsorption/desorption (H{sub ads}/H{sub des}) reaction. The oxidation of Ta to the stoichiometric oxide (Ta{sub 2}O{sub 5}) increases with increasing the annealing temperature as revealed from XPS and X-ray diffraction (XRD) measurements. The higher the annealing temperature the larger is the enhancement in the H{sub ads}/H{sub des} reaction at TaO{sub x}/Pt electrode. The extraordinary increase in the hydrogen adsorption/desorption at the electrode annealed at 600 deg. C is explained on the basis of a hydrogen spillover-reverse spillover mechanism. The hydrogen adsorption at the TaO{sub x}/Pt electrode is a diffusion-controlled process.

Adsorption/desorption properties of vacuum materials for the 6 GeV synchrotron

International Nuclear Information System (INIS)

Krauss, A.R.

1985-01-01

Considerable attention must be paid to the vacuum and adsorption/desorption properties of all materials installed inside the vacuum envelope if the design goals of the 6 GeV synchrotron are to be met. Unfortunately, the data is very sparse in several key areas. Additionally, some procedures normally associated with good vacuum practice, such as air baking, may prove to be totally unsuitable on the basis of desorption properties. We present here a brief discussion of the adsorption, outgassing, electron-stimulated desorption (ESD), and photon-stimulated desorption (PSD) properties of vacuum materials as they relate to the design of a 6 GeV synchrotron

Hydrogen absorption properties of U6Mn and U6Ni

International Nuclear Information System (INIS)

Ito, H.; Yamawaki, M.; Yamamoto, T.

1998-01-01

The hydrogen absorption properties of U, U 6 Mn and U 6 Ni were investigated at hydrogen pressures below 10 5 Pa. The pressure-composition (P-C) isotherms of U, U 6 Mn and U 6 Ni were obtained and the amounts of absorbed hydrogen for U, U 6 Mn and U 6 Ni were determined to be 3, 16.6 and 16.0 for x in MH x , where M is U, U 6 Mn and U 6 Ni, respectively. The desorption plateau pressures at 573 K decreased in the order: U 6 Mn-H>U 6 Ni-H>U-H. In addition, the results for the amounts of absorbed hydrogen suggests the formation of ternary hydrides U 6 MnH 18 and U 6 NiH 14 . (orig.)

Cs-137 sorption and desorption in relation to properties of 17 soils

International Nuclear Information System (INIS)

Kerpen, W.

1988-01-01

For Cs-137 sorption and desorption studies material of Ap and Ah horizons from 17 soils with wide varying soil properties was selected. The soils were: Podsol, Luvisol, Chernozem, Cambisol, Phaeozem, Arenosol, Gleysol and other soils. The Cs-137 sorption and desorption experiments were carried out in aqueous solution (20 g of soil) under standardized conditions for two reasons: (1) to determine the amounts of Cs-137 sorption, desorption and remains as a function of different soils and (2) to evaluate the soil parameters which govern the sorption, desorption processes. Concerning the second point the sorption values, the amount of 137 Cs desorbed within four desorption cycles and the 137 Cs remains after four desorption cycles were correlated with pH, grain size, sorption capacity (CEC), and other soil properties. It will be shown that generally Cs-137 sorption, desorption and remains depend primarily on the pH of the soil. The middle sand proved to be an indicator for the strenght of sorption, and desorption processes. Sorption and desorption studies lead to the same results as found in biotest experiments

Hydrogen absorption-desorption properties of Ti0.32Cr0.43V0.25 alloy

International Nuclear Information System (INIS)

Cho, Sung-Wook; Shim, Gunchoo; Choi, Good-Sun; Park, Choong-Nyeon; Yoo, Jeong-Hyun; Choi, Jeon

2007-01-01

Ti 0.32 Cr 0.43 V 0.25 alloy specimens were heat treated, and its various hydrogen storage properties were measured at 303 K to examine its potential as a hydrogen storage material. The heat treatment improved not only the total and the effective hydrogen storage capacities, but also the plateau flatness. The heat of hydride formation was approximately -36 kJ/mol H 2 . The effective hydrogen storage capacity remained at approximately 2 wt% after 1000 cycles of pressure swing cyclic tests. The hydrogen storage capacity could be recovered almost to the initial state by reactivating the alloy. The hydrogen absorption rate increased with the repetition of cycling for the first several cycles and remained almost constant afterward. At the 504th cycle, more than 98% of the hydrogen was absorbed within the first 2 min. X-ray diffraction (XRD) patterns showed that the crystal structure of the alloy became more amorphous as the number of cycles increased

Hydrogen storage thermodynamics and kinetics of LaMg11Ni + x wt.% Ni (x = 100, 200) alloys synthesized by mechanical milling

International Nuclear Information System (INIS)

Zhang, Yanghuan; Jia, Zhichao; Central Iron and Steel Research Institute, Beijing; Yuan, Zeming; Qi, Yan; Zhao, Dongliang; Hou, Zhonghui

2016-01-01

LaMg 11 Ni + x wt.% Ni (x = 100, 200) composite hydrogen storage alloys with a nanocrystalline/amorphous structure were synthesized using ball milling technology. The effects of Ni content and milling time on hydrogen storage thermodynamics and dynamics of the alloys were investigated systematically. The hydrogen desorption properties were assessed using a Sieverts apparatus and differential scanning calorimetry. The thermodynamic parameters for the hydrogen absorption and desorption were calculated using the Van't Hoff equation. The hydrogen desorption activation energies of the hydrogenated alloys were also estimated by Arrhenius and Kissinger methods. Results indicate that the amount of Ni added has no effect on the thermodynamics of the alloys, but it significantly improves their absorption and desorption kinetics. Furthermore, the milling time has a great influence on the hydrogen storage properties. To be specific, the hydrogen absorption capacities reach the maximum values with the variation of milling time, and the hydrogen desorption activation energy obviously decreases with increasing milling time.

Reduction of hydrogen desorption temperature of ball-milled MgH2 by NbF5 addition

International Nuclear Information System (INIS)

Recham, N.; Bhat, V.V.; Kandavel, M.; Aymard, L.; Tarascon, J.-M.; Rougier, A.

2008-01-01

Enhanced sorption properties of ball-milled MgH 2 are reported by adding NbF 5 . Among various catalyst amounts, 2 mol% of NbF 5 reveals to be the optimum concentration leading to significant reduction of the desorption temperature as well as faster kinetics of ball-milled MgH 2 . At 200 deg. C, temperature at which MgH 2 does not show any activity, MgH 2NbF 5 /2mol% composite desorbs 3.2 wt.% of H 2 in 50 mins. Interestingly, the addition of NbF 5 is also associated with an increase in the desorption pressure. At 300 deg. C, MgH 2NbF 5 /2mol% composite starts to desorb hydrogen at 600 mbar in comparison with 1 mbar for MgH 2 . Further improvements were successfully achieved by pre-grinding NbF 5 prior to ball-milling the catalyst with MgH 2 . Such pre-ground NbF 5 catalyzed MgH 2 composite desorbs 3 wt.% of H 2 at 150 deg. C. Improved properties are associated with smaller activation energies down to values close to the enthalpy of formation of MgH 2 . Finally, the mechanism at the origin of the enhancement is discussed in terms of catalyst stability, MgF 2 formation and electronic density localization

STM-Induced Hydrogen Desorption via a Hole Resonance

DEFF Research Database (Denmark)

Stokbro, Kurt; Thirstrup, C.; Sakurai, M.

1998-01-01

We report STM-induced desorption of H from Si(100)-H(2 X 1) at negative sample bias. The desorption rate exhibits a power-law dependence on current and a maximum desorption rate at -7 V. The desorption is explained by vibrational heating of H due to inelastic scattering of tunneling holes...... with the Si-H 5 sigma hole resonance. The dependence of desorption rate on current and bias is analyzed using a novel approach for calculating inelastic scattering, which includes the effect of the electric field between tip and sample. We show that the maximum desorption rate at -7 V is due to a maximum...

The electrochemical characteristics of Mg2Ni nanocrystalline hydrogen storage alloy

International Nuclear Information System (INIS)

Zhang Ling; Zhou Xiaosong; Peng Shuming

2008-06-01

The nanocrystalline Mg 2 Ni materials were prepared by mechanical alloying. The cyclic voltametry results indicated that the potential of oxidation peak was shift as the scan rate increased and the absorption property of Mg 2 Ni prepared by mechanical alloying was increased even at ambient temperature. The absorption and desorption of hydrogen in Mg 2 Ni alloy were remarkably accelerated with the rising temperature. Small angel X-ray scattering results indicated that the Mg 2 Ni powder have 1-5 nm and 5-10 nm particle size distribution, which increased the acting sites of hydrogen absorption/desorption reaction and decreased the diffusion path of hydrogen desorption. It was induced to the enhanced performance of Mg 2 Ni nanocrystalline powder. The cycle life investigated results indicated that the activation property of Mg 2 Ni nanocrystal-line hydrogen storage alloy electrode was excellent, the capacitance maintenance ration was 66% after 200 cycles. The coating of epoxy resin on one side of the electrode had no effect on the activation property and the capacitance maintenance ration was better than the uncoating one. But the anode peak current value and the cathodic peak current value were decreased remarkably which indicated that the hydrogen absorption/desorption rate and the charge/discharge degree had decreased. (authors)

Effect Of The Desorption-Recombination Temperature On The Microstructure And Magnetic Properties Of HDDR Processed Nd-Fe-B Powders

Directory of Open Access Journals (Sweden)

Lee J.-G.

2015-06-01

Full Text Available The effect of the desorption-recombination temperature on the microstructure and magnetic properties of hydrogenation-disproportionation-desorption-recombination (HDDR processed Nd-Fe-B powders was studied. The NdxB6.4Ga0.3Nb0.2Febal (x=12.5-13.5, at.% casting alloys were pulverized after homogenizing annealing, and then subjected to HDDR treatment. During the HDDR process, desorption-recombination (DR reaction was induced at two different temperature, 810°C and 820°C. The higher Nd content resulted in enhanced coercivity of the HDDR powder, and which was attributed to the thicker and more uniform Nd-rich phase along grain boundaries. But this uniform Nd-rich phase induced faster grain growth. The remanence of the powder DR-treated at 820°C is higher than that DR-treated at 810°C. In addition, it was also confirmed that higher DR temperature is much more effective to improve squareness.

Hydrogen embrittlement property of a 1700-MPa-class ultrahigh-strength tempered martensitic steel

Energy Technology Data Exchange (ETDEWEB)

Li Songjie; Zhang Boping [School of Materials Science and Engineering, University of Science and Technology Beijing, No. 30 Xueyuan Road, Hidian Zone, Beijing 100083 (China); Akiyama, Eiji; Yuuji, Kimura; Tsuzaki, Kaneaki [Structural Metals Center, National Institute for Materials Science, 1-2-1 Sengen, Tsukuba, Ibaraki 305-0047 (Japan); Uno, Nobuyoshi, E-mail: AKIYAMA.Eiji@nims.go.j [Nippon Steel and Sumikin Metal Products Co, Ltd, SA Bldg., 17-12 Kiba 2-chome, Koto-ku, Tokyo (Japan)

2010-04-15

The hydrogen embrittlement property of a prototype 1700-MPa-class ultrahigh-strength steel (NIMS17) containing hydrogen traps was evaluated using a slow strain rate test (SSRT) after cathodic hydrogen precharging, cyclic corrosion test (CCT) and atmospheric exposure. The hydrogen content in a fractured specimen was measured after SSRT by thermal desorption spectroscopy (TDS). The relationship between fracture stress and hydrogen content for the hydrogen-precharged specimens showed that the fracture stress of NIMS17 steel was higher, at a given hydrogen content, than that of conventional AISI 4135 steels with tensile strengths of 1300 and 1500 MPa. This suggests better resistance of NIMS17 steel to hydrogen embrittlement. However, hydrogen uptake to NIMS17 steel under CCT and atmospheric exposure decreased the fracture stress. This is because of the stronger hydrogen uptake to the steel containing hydrogen traps than to the AISI 4135 steels. Although NIMS17 steel has a higher strength level than AISI 4135 steel with a tensile strength of 1500 MPa, the decrease in fracture stress is similar between these steels.

Hydrogen embrittlement property of a 1700-MPa-class ultrahigh-strength tempered martensitic steel

Directory of Open Access Journals (Sweden)

Songjie Li, Eiji Akiyama, Kimura Yuuji, Kaneaki Tsuzaki, Nobuyoshi Uno and Boping Zhang

2010-01-01

Full Text Available The hydrogen embrittlement property of a prototype 1700-MPa-class ultrahigh-strength steel (NIMS17 containing hydrogen traps was evaluated using a slow strain rate test (SSRT after cathodic hydrogen precharging, cyclic corrosion test (CCT and atmospheric exposure. The hydrogen content in a fractured specimen was measured after SSRT by thermal desorption spectroscopy (TDS. The relationship between fracture stress and hydrogen content for the hydrogen-precharged specimens showed that the fracture stress of NIMS17 steel was higher, at a given hydrogen content, than that of conventional AISI 4135 steels with tensile strengths of 1300 and 1500 MPa. This suggests better resistance of NIMS17 steel to hydrogen embrittlement. However, hydrogen uptake to NIMS17 steel under CCT and atmospheric exposure decreased the fracture stress. This is because of the stronger hydrogen uptake to the steel containing hydrogen traps than to the AISI 4135 steels. Although NIMS17 steel has a higher strength level than AISI 4135 steel with a tensile strength of 1500 MPa, the decrease in fracture stress is similar between these steels.

Hydrogen embrittlement property of a 1700-MPa-class ultrahigh-strength tempered martensitic steel

International Nuclear Information System (INIS)

Li Songjie; Zhang Boping; Akiyama, Eiji; Yuuji, Kimura; Tsuzaki, Kaneaki; Uno, Nobuyoshi

2010-01-01

The hydrogen embrittlement property of a prototype 1700-MPa-class ultrahigh-strength steel (NIMS17) containing hydrogen traps was evaluated using a slow strain rate test (SSRT) after cathodic hydrogen precharging, cyclic corrosion test (CCT) and atmospheric exposure. The hydrogen content in a fractured specimen was measured after SSRT by thermal desorption spectroscopy (TDS). The relationship between fracture stress and hydrogen content for the hydrogen-precharged specimens showed that the fracture stress of NIMS17 steel was higher, at a given hydrogen content, than that of conventional AISI 4135 steels with tensile strengths of 1300 and 1500 MPa. This suggests better resistance of NIMS17 steel to hydrogen embrittlement. However, hydrogen uptake to NIMS17 steel under CCT and atmospheric exposure decreased the fracture stress. This is because of the stronger hydrogen uptake to the steel containing hydrogen traps than to the AISI 4135 steels. Although NIMS17 steel has a higher strength level than AISI 4135 steel with a tensile strength of 1500 MPa, the decrease in fracture stress is similar between these steels.

Theoretical study of hydrogen storage in metal hydrides.

Science.gov (United States)

Oliveira, Alyson C M; Pavão, A C

2018-05-04

Adsorption, absorption and desorption energies and other properties of hydrogen storage in palladium and in the metal hydrides AlH 3 , MgH 2 , Mg(BH 4 ) 2 , Mg(BH 4 )(NH 2 ) and LiNH 2 were analyzed. The DFT calculations on cluster models show that, at a low concentration, the hydrogen atom remains adsorbed in a stable state near the palladium surface. By increasing the hydrogen concentration, the tetrahedral and the octahedral sites are sequentially occupied. In the α phase the tetrahedral site releases hydrogen more easily than at the octahedral sites, but the opposite occurs in the β phase. Among the hydrides, Mg(BH 4 ) 2 shows the highest values for both absorption and desorption energies. The absorption energy of LiNH 2 is higher than that of the palladium, but its desorption energy is too high, a recurrent problem of the materials that have been considered for hydrogen storage. The release of hydrogen, however, can be favored by using transition metals in the material structure, as demonstrated here by doping MgH 2 with 3d and 4d-transition metals to reduce the hydrogen atomic charge and the desorption energy.

Functional nanometers for hydrogen storage produced by ball milling

Energy Technology Data Exchange (ETDEWEB)

Czujko, T. [Waterloo Univ., ON (Canada). Dept. of Mechanical and Mechatronics Engineering]|[Military Univ. of Technology, Warsaw (Poland). Dept. of Advanced Materials and Technologies; Varin, R.A. [Waterloo Univ., ON (Canada). Dept. of Mechanical and Mechatronics Engineering; Wronski, Z.S. [Natural Resources Canada, Ottawa, ON (Canada). CANMET Energy Technology Centre, Hydrogen Fuel Cells and Transportation; Zaranski, Z. [Military Univ. of Technology, Warsaw (Poland). Dept. of Advanced Materials and Technologies

2008-07-01

It is becoming increasingly important to switch to cleaner alternative energy carriers such as hydrogen, as environmental concerns over greenhouse gas emissions from the burning of fossil fuel increase. Specifically, there is a need for efficient on-board hydrogen storage technologies for vehicular applications. This paper discussed three different methods of hydrogen desorption temperature reduction and desorption kinetics of nanostructured hydrides. The first method was based on substantial hydride particle size refinement. The second method utilized catalytic effects of nanometric n-alumina (Al{sub 2}O{sub 3}), n-yttrium oxide powder (Y{sub 2}O{sub 3}) and n-nickel (Ni) additives. The third method was based on a composite of nanohydride mixtures. The composite approach was applied to the magnesium hydride (MgH{sub 2}) plus sodium tetrahydridoborate (NaBH{sub 4}) and lithium aluminum hydride (LiAlH{sub 4}) systems. The paper presented the effects of nanostructuring and nanocatalytic additives on Mg hydride desorption properties as well as a composite behaviour of nanostructured complex hydrides. It was concluded that milling of commercial MgH{sub 2} with the nano-oxide additives had a limited effect on improving the hydrogen storage properties. The addition of specialty Inco nanometric Ni reduced the hydrogen desorption temperature considerably. 28 refs., 1 tab., 9 figs.

Molecular Beam-Thermal Desorption Spectrometry (MB-TDS) Monitoring of Hydrogen Desorbed from Storage Fuel Cell Anodes.

Science.gov (United States)

Lobo, Rui F M; Santos, Diogo M F; Sequeira, Cesar A C; Ribeiro, Jorge H F

2012-02-06

Different types of experimental studies are performed using the hydrogen storage alloy (HSA) MlNi 3.6 Co 0.85 Al 0.3 Mn 0.3 (Ml: La-rich mischmetal), chemically surface treated, as the anode active material for application in a proton exchange membrane fuel cell (PEMFC). The recently developed molecular beam-thermal desorption spectrometry (MB-TDS) technique is here reported for detecting the electrochemical hydrogen uptake and release by the treated HSA. The MB-TDS allows an accurate determination of the hydrogen mass absorbed into the hydrogen storage alloy (HSA), and has significant advantages in comparison with the conventional TDS method. Experimental data has revealed that the membrane electrode assembly (MEA) using such chemically treated alloy presents an enhanced surface capability for hydrogen adsorption.

The kinetics of hydrogen absorption/desorption within nanostructured composite Ni{sub 79.1}Co{sub 18.6}Cu{sub 2.3} alloy using resistometry

Energy Technology Data Exchange (ETDEWEB)

Spasojevic, M., E-mail: ljiljana.spasojevic51@yahoo.com [Joint Laboratory for Advanced Materials of the Serbian Academy of Science and Arts, Section for Amorphous Systems, Svetog Save 65, 32000 Cacak, Republic of Serbia (Serbia); Faculty of Agronomy Cacak, University of Kragujevac, Cara Dusana 34, 32000 Cacak, Republic of Serbia (Serbia); Maricic, A. [Joint Laboratory for Advanced Materials of the Serbian Academy of Science and Arts, Section for Amorphous Systems, Svetog Save 65, 32000 Cacak, Republic of Serbia (Serbia); Ribic Zelenovic, L. [Joint Laboratory for Advanced Materials of the Serbian Academy of Science and Arts, Section for Amorphous Systems, Svetog Save 65, 32000 Cacak, Republic of Serbia (Serbia); Faculty of Agronomy Cacak, University of Kragujevac, Cara Dusana 34, 32000 Cacak, Republic of Serbia (Serbia); Krstajic, N.; Spasojevic, P. [Faculty of Technology and Metallurgy, University of Belgrade, Karnegijeva 4, 11000 Belgrade, Republic of Serbia (Serbia)

2013-02-25

Highlights: Black-Right-Pointing-Pointer Nanostructured Ni{sub 79.1}Co{sub 18.6}Cu{sub 2.3} powder was obtained by electrochemical deposition. Black-Right-Pointing-Pointer Correlation observed between electrical conductivity and absorbed hydrogen amount. Black-Right-Pointing-Pointer Hydrogen absorption/desorption mechanism was determined. - Abstract: Ni{sub 79.1}Co{sub 18.6}Cu{sub 2.3} powder was obtained by electrochemical deposition from an ammonium sulfate bath. The structure and surface morphology of the powder were detected by X-ray diffraction (XRD) and scanning electron microscopy (SEM), respectively. The electrochemically obtained Ni{sub 79.1}Co{sub 18.6}Cu{sub 2.3} alloy contained an amorphous phase and nanocrystals with an average size of 6.8 nm of FCC phase of the solid solution of cobalt and copper in nickel. Nanocrystals were characterized by a high average microstrain value and high minimum density of chaotically distributed dislocations. X-ray analysis also showed that powder hydrogenation at an elevated temperature of up to 200 Degree-Sign C did not change unit cell parameters and mean crystallite size value. SEM images show the formation of two shapes of powder particles: large cauliflower-like particles and small dendritic ones. Powder pressing at 10 MPa and at 25 Degree-Sign C gave samples that were analyzed for hydrogen absorption/desorption within the temperature range of 160-200 Degree-Sign C. Changes in electrical resistivity during absorption/desorption were monitored. The reciprocal value of resistivity (electrical conductivity) was found to increase linearly with increasing amount of absorbed hydrogen. The experimental results were used to propose an absorption/desorption mechanism. The adsorbed hydrogen molecule dissociates on alloy surface, forming adsorbed atoms. Adatoms penetrate and diffuse into the bulk of the alloy, simultaneously donating their electrons to the conduction band of the alloy. The increase in the concentration of free

Analysis of hydrogen distribution on Mg-Ni alloy surface by scanning electron-stimulated desorption ion microscope (SESDIM)

International Nuclear Information System (INIS)

Yamaga, Atsushi; Hibino, Kiyohide; Suzuki, Masanori; Yamada, Masaaki; Tanaka, Kazuhide; Ueda, Kazuyuki

2008-01-01

Hydrogen distribution and behavior on a Mg-Ni alloy surface are studied by using a time-of-flight electron-stimulated desorption (TOF-ESD) microscopy and a scanning electron microscope with energy dispersive X-ray spectroscopy (SEM-EDX). The desorbed hydrogen ions are energy-discriminated and distinguished into two characters in the adsorbed states, which belong to Mg 2 Ni grains and the other to oxygen-contaminated Mg phase at the grain boundaries. Adsorbed hydrogen is found to be stable up to 150 deg. C, but becomes thermally unstable around at 200 deg. C

Molecular Beam-Thermal Desorption Spectrometry (MB-TDS Monitoring of Hydrogen Desorbed from Storage Fuel Cell Anodes

Directory of Open Access Journals (Sweden)

Jorge H. F. Ribeiro

2012-02-01

Full Text Available Different types of experimental studies are performed using the hydrogen storage alloy (HSA MlNi3.6Co0.85Al0.3Mn0.3 (Ml: La-rich mischmetal, chemically surface treated, as the anode active material for application in a proton exchange membrane fuel cell (PEMFC. The recently developed molecular beam—thermal desorption spectrometry (MB-TDS technique is here reported for detecting the electrochemical hydrogen uptake and release by the treated HSA. The MB-TDS allows an accurate determination of the hydrogen mass absorbed into the hydrogen storage alloy (HSA, and has significant advantages in comparison with the conventional TDS method. Experimental data has revealed that the membrane electrode assembly (MEA using such chemically treated alloy presents an enhanced surface capability for hydrogen adsorption.

Data compilation for particle impact desorption

International Nuclear Information System (INIS)

Oshiyama, Takashi; Nagai, Siro; Ozawa, Kunio; Takeuchi, Fujio.

1984-05-01

The desorption of gases from solid surfaces by incident electrons, ions and photons is one of the important processes of hydrogen recycling in the controlled thermonuclear reactors. We have surveyed the literature concerning the particle impact desorption published through 1983 and compiled the data on the desorption cross sections and desorption yields with the aid of a computer. This report presents the results obtained for electron stimulated desorption, the desorption cross sections and yields being given in graphs and tables as functions of incident electron energy, surface temperature and gas exposure. (author)

Liquid hydrogen properties

International Nuclear Information System (INIS)

Choi, Jung Woon; Kim, Y. J.; Lee, K. H.; Kim, H. I.; Han, K. Y.; Park, J.H.

2004-03-01

The purpose of this report is to provide the input data, whose characteristic is thermodynamic and transport, in the form of equation for the thermo-hydraulic calculations using hydrogen as a working substance. The considered data in this report are particularly focused on the properties of para-hydrogen and of equilibrium-hydrogen around the working temperature range of the HANARO-CNS. The discussed properties of hydrogen are, in turn, the pressure of saturated vapors, the density, the heat of vaporization, thermal conductivity, viscosity, and heat capacity. Several equations to fit the above-mentioned experimental data allow calculating the various properties of liquid hydrogen with high accuracy at all considered temperatures

Desorption of hydrogen from magnesium hydride: in-situ electron diffraction study

International Nuclear Information System (INIS)

Paik, B.; Jones, I.P.; Walton, A.; Mann, V.; Book, D.; Harris, I.R.

2009-01-01

The dynamics of a phase change has been studied where electron beam in Transmission Electron Microscope (TEM) has been used to transform MgH 2 into magnesium. A combination of in-situ Electron Diffraction (ED) and an in-situ Electron Energy Loss Spectroscopy (EELS) study under ED mode describes the phase transformation in terms of, respectively, change in the crystal structure and Plasmon energy shift. The orientation relation [001] MgH2 //[-2110] Mg and (-110) MgH2 //(0001) Mg , obtained from the ED study, has been used to propose a model for the movements of magnesium atoms in the structural change to describe the dynamics of the process. The in-situ EELS study has been compared with the existing H-desorption model. The study aims to describe the sorption dynamics of hydrogen in MgH 2 which is a base material for a number of promising hydrogen storage systems. (author)

Catalytic effect of Ni, Mg2Ni and Mg2NiH4 upon hydrogen desorption from MgH2

Czech Academy of Sciences Publication Activity Database

Čermák, Jiří; David, Bohumil

2011-01-01

Roč. 36, č. 21 (2011), s. 13614-13620 ISSN 0360-3199 R&D Projects: GA ČR GA106/09/0814; GA ČR(CZ) GAP108/11/0148 Institutional research plan: CEZ:AV0Z20410507 Keywords : MgH2 * Hydrogen storage * Hydrogen desorption * Catalysis Subject RIV: JG - Metallurgy Impact factor: 4.054, year: 2011

High surface area niobium oxides as catalysts for improved hydrogen sorption properties of ball milled MgH2

International Nuclear Information System (INIS)

Bhat, V.V.; Rougier, A.; Aymard, L.; Nazri, G.A.; Tarascon, J.-M.

2008-01-01

We report, high surface area (up to 200 m 2 /g) nanocrystalline niobium oxide (so called p-Nb 2 O 5 ) synthesized by 'chimie douce' route and its importance in enhancing the hydrogen sorption properties of MgH 2 . p-Nb 2 O 5 induces faster kinetics than commonly used commercial Nb 2 O 5 (c-Nb 2 O 5 ) when ball milled with MgH 2 (named (MgH 2 ) catalyst ) by reducing the time of desorption from 35 min in (MgH 2 ) c-Nb 2 O 5 to 12 min in (MgH 2 ) p-Nb 2 O 5 at 300 deg. C. The BET surface area of as-prepared Nb 2 O 5 was tuned by heat treatment and its effect on sorption properties was studied. Among them, both p-Nb 2 O 5 and Nb 2 O 5 :350 (p-Nb 2 O 5 heated to 350 deg. C with a BET specific surface area of 46 m 2 /g) desorb 5 wt.% within 12 min, exhibiting the best catalytic activity. Furthermore, thanks to the addition of high surface area Nb 2 O 5 , the desorption temperature was successfully lowered down to 200 deg. C, with a significant amount of desorbed hydrogen (4.5 wt.%). In contrast, the composite (MgH 2 ) c-Nb 2 O 5 shows no desorption at this 'low' temperature

Physicochemical and thermodynamic investigation of hydrogen absorption and desorption in LaNi3.8Al1.0Mn0.2 using the statistical physics modeling

Science.gov (United States)

Bouaziz, Nadia; Ben Manaa, Marwa; Ben Lamine, Abdelmottaleb

2018-06-01

In the present work, experimental absorption and desorption isotherms of hydrogen in LaNi3.8Al1.0Mn0.2 metal at two temperatures (T = 433 K, 453 K) have been fitted using a monolayer model with two energies treated by statistical physics formalism by means of the grand canonical ensemble. Six parameters of the model are adjusted, namely the numbers of hydrogen atoms per site nα and nβ, the receptor site densities Nmα and Nmβ, and the energetic parameters Pα and Pβ. The behaviors of these parameters are discussed in relationship with temperature of absorption/desorption process. Then, a dynamic investigation of the simultaneous evolution with pressure of the two α and β phases in the absorption and desorption phenomena using the adjustment parameters. Thanks to the energetic parameters, we calculated the sorption energies which are typically ranged between 276.107 and 310.711 kJ/mol for absorption process and between 277.01 and 310.9 kJ/mol for desorption process comparable to usual chemical bond energies. The calculated thermodynamic parameters such as entropy, Gibbs free energy and internal energy from experimental data showed that the absorption/desorption of hydrogen in LaNi3.8Al1.0Mn0.2 alloy was feasible, spontaneous and exothermic in nature.

Changes in mechanical properties following cyclic prestressing of martensitic steel containing vanadium carbide in presence of nondiffusible hydrogen

Energy Technology Data Exchange (ETDEWEB)

Kaneko, Mao; Doshida, Tomoki [Graduate School of Science and Technology, Sophia University, Tokyo 102-8554 (Japan); Takai, Kenichi, E-mail: takai@me.sophia.ac.jp [Department of Engineering and Applied Science, Sophia University, Tokyo 102-8554 (Japan)

2016-09-30

Changes in the states of nondiffusible hydrogen and mechanical properties after cyclic prestressing in the presence of only nondiffusible hydrogen were examined for martensitic steel containing vanadium carbide. The relationship between the change in the state of nondiffusible hydrogen and mechanical properties was also investigated. The hydrogen desorption profile in the high-temperature range decreased and that in the low-temperature range increased with increasing stress amplitude during cyclic prestressing in the presence of only nondiffusible hydrogen. Thus, the application of cyclic prestressing changed the state of hydrogen from a stable to an unstable one because of vacancies and their clusters. Hydrogen embrittlement susceptibility after cyclic prestressing increased with increasing stress amplitude and number of prestressing cycles in the presence of only nondiffusible hydrogen. This relationship indicates that hydrogen embrittlement susceptibility increased with the increasing amount of hydrogen detrapped from trap sites of nondiffusible hydrogen during cyclic prestressing. These results revealed that nondiffusible hydrogen easily detrapped from vanadium carbide due to the application of cyclic prestress and probably interacted with vacancies and their clusters, thus increasing hydrogen embrittlement susceptibility. The change of nondiffusible hydrogen to diffusible hydrogen and accumulation of vacancies and their clusters during cyclic prestressing are concluded to be the dominant factors in hydrogen embrittlement after the application of cyclic prestress.

Hydrogen storage study on Ti2CrV and ZrFe1.8V0.2 composite system

International Nuclear Information System (INIS)

Banerjee, S.; Kumar, A.; Pillai, C.G.S.; Sudarsan, V.

2012-01-01

Ti 2 CrV is reported to have one of the highest hydrogen storage capacities (more than 4 wt. %) among the bcc phase transition metal alloys. It has been found from the earlier study that Ti 2 CrV alloy shows quite good hydrogen absorption property but the desorption temperature is on the higher side. The in-situ temperature programmed desorption profile shows that the hydrogen desorption starts from 120℃ and the desorption peak comes at 180℃, which is slightly high for the vehicular application. On the other hand ZrFe 1.8 V 0.2 Laves phase alloy has low hydrogen absorption capacity, but at the room temperature it can desorp all its hydrogen. The pressure composition isotherm of ZrFe 1.8 V 0.2 alloy generated during the experiment shows the typical characteristics of the room temperature reversible hydride. The in-situ temperature programmed desorption shows that the hydride can desorb all the hydrogen below room temperature

Testosterone sorption and desorption: Effects of soil particle size

Energy Technology Data Exchange (ETDEWEB)

Qi, Yong, E-mail: yqi01@unomaha.edu [Civil Engineering Dept., University of Nebraska-Lincoln at Omaha Campus, Omaha, NE 68182 (United States); Zhang, Tian C. [Civil Engineering Dept., University of Nebraska-Lincoln at Omaha Campus, Omaha, NE 68182 (United States); Ren, Yongzheng [School of Environmental Science and Engineering, Huazhong University of Science and Technology, Wuhan 430074 (China)

2014-08-30

Graphical abstract: - Highlights: • Smaller soil particles have higher sorption and lower desorption rates. • The sorption capacity ranks as clay > silt > sand. • Small particles like clays have less potential for desorption. • Colloids (clays) have high potential to facilitate the transport of hormones in soil–water environments. - Abstract: Soils contain a wide range of particles of different diameters with different mobility during rainfall events. Effects of soil particles on sorption and desorption behaviors of steroid hormones have not been investigated. In this study, wet sieve washing and repeated sedimentation methods were used to fractionate the soils into five ranges. The sorption and desorption properties and related mechanisms of testosterone in batch reactors filled with fractionated soil particles were evaluated. Results of sorption and desorption kinetics indicate that small soil particles have higher sorption and lower desorption rates than that of big ones. Thermodynamic results show the sorption processes are spontaneous and exothermal. The sorption capacity ranks as clay > silt > sand, depending mainly on specific surface area and surface functional groups. The urea control test shows that hydrogen bonding contributes to testosterone sorption onto clay and silt but not on sand. Desorption tests indicate sorption is 36–65% irreversible from clay to sand. Clays have highest desorption hysteresis among these five soil fractions, indicating small particles like clays have less potential for desorption. The results provide indirect evidence on the colloid (clay)-facilitated transport of hormones (micro-pollutants) in soil environments.

Data compilation for particle-impact desorption, 2

International Nuclear Information System (INIS)

Oshiyama, Takashi; Nagai, Siro; Ozawa, Kunio; Takeutchi, Fujio.

1985-07-01

The particle impact desorption is one of the elementary processes of hydrogen recycling in controlled thermonuclear fusion reactors. We have surveyed the literature concerning the ion impact desorption and photon stimulated desorption published through the end of 1984 and compiled the data on the desorption cross sections and yields with the aid of a computer. This report presents the results of the compilation in graphs and tables as functions of incident energy, surface temperature and surface coverage. (author)

Improved hydrogen storage properties of MgH2 catalyzed with TiO2

Science.gov (United States)

Jangir, Mukesh; Meena, Priyanka; Jain, I. P.

2018-05-01

In order to improve the hydrogenation properties of the MgH2, various concentration of rutile Titanium Oxide (TiO2) (X wt%= 5, 10, 15 wt %) is added to MgH2 by ball milling and the catalytic effect of TiO2 on hydriding/dehydriding properties of MgH2 has been investigated. Result shows that the TiO2 significantly reduced onset temperature of desorption. Onset temperature as low as 190 °C were observed for the MgH2-15 wt% TiO2 sample which is 60 °C and 160 °C lower than the as-milled and as-received MgH2. Fromm the Kissinger plot the activation energy of 15 wt% TiO2 added sample is calculated to be -75.48 KJ/mol. These results indicate that the hydrogenation properties of MgH2-TiO2 have been improved compared to the as-milled and as-received MgH2. Furthermore, XRD and XPS were performed to characterize the structural evolution upon milling and dehydrogenation.

Study on glass-forming ability and hydrogen storage properties of amorphous Mg60Ni30La10−xCox (x = 0, 4) alloys

International Nuclear Information System (INIS)

Lv, Peng; Wang, Zhong-min; Zhang, Huai-gang; Balogun, Muhammad-Sadeeq; Ji, Zi-jun; Deng, Jian-qiu; Zhou, Huai-ying

2013-01-01

Mg 60 Ni 30 La 10−x Co x (x = 0, 4) amorphous alloys were prepared by rapid solidification, using a melt-spinning technique. X-ray diffraction and differential scanning calorimetry analysis were employed to measure their microstructure, thermal stability and glass-forming ability, and hydrogen storage properties were studied by means of PCTPro2000. Based on differential scanning calorimetry results, their glass-forming ability and thermal stability were investigated by Kissinger method, Lasocka curves and atomic cluster model, respectively. The results indicate that glass-forming ability, thermal properties and hydrogen storage properties in the Mg-rich corner of Mg–Ni–La–Co system alloys were enhanced by Co substitution for La. It can be found that the smaller activation energy (ΔΕ) and frequency factor (υ 0 ), the bigger value of B (glass transition point in Lasocka curves), and higher glass-forming ability of Mg–Ni–La–Co alloys would be followed. In addition, atomic structure parameter (λ), deduced from atomic cluster model is valuable in the design of Mg–Ni–La–Co system alloys with good glass-forming ability. With an increase of Co content from 0 to 4, the hydrogen desorption capacity within 4000 s rises from 2.25 to 2.85 wt.% at 573 K. - Highlights: • Amorphous Mg 60 Ni 30 La 10−x Co x (x = 0 and 4) alloys were produced by melt spinning. • The GFA and hydrogen storage properties were enhanced by Co substitution for La. • With an increase of Co content, the hydrogen desorption capacity rises at 573 K

Hydrogen storage properties of carbon nanomaterials and carbon containing metal hydrides

Energy Technology Data Exchange (ETDEWEB)

Maehlen, Jan Petter

2003-07-01

The topic of this thesis is structural investigations of carbon containing materials in respect to their hydrogen storage properties. This work was initially triggered by reports of extremely high hydrogen storage capacities of specific carbon nanostructures. It was decided to try to verify and understand the mechanisms in play in case of the existence of such high hydrogen densities in carbon. Two different routes towards the goal were employed; by studying selected hydrides with carbon as one of its constituents (mainly employing powder diffraction techniques in combination with hydrogen absorption and desorption measurements) and by carefully conducting hydrogen sorption experiments on what was believed to be the most ''promising'' carbon nanomaterial sample. In the latter case, a lot of effort was attributed to characterisations of different carbon nanomaterial containing samples with the aid of electron microscopy. Three different carbon-containing metal hydride systems, Y2C-H, YCoC-H and Y5SiC0.2-H, were examined. A relation between hydrogen occupation and the local arrangement of metal and carbon atoms surrounding the hydrogen sites was established. Several characteristic features of the compounds were noted in addition to solving the structure of the former unknown deuterideY5Si3C0.2D2.0 by the use of direct methods. Several carbon-nanomaterial containing samples were studied by means of transmission electron microscopy and powder diffraction, thus gaining knowledge concerning the structural aspects of nanomaterials. Based on these investigations, a specific sample containing a large amount of open-ended single-wall carbon nanotubes was chosen for subsequent hydrogen storage experiments. The latter experiments revealed moderate hydrogen storage capacities of the nanotubes not exceeding the values obtained for more conventional forms of carbon. These two different routes in investigating the hydrogen storage properties of carbon and carbon containing alloys

Hydrogen storage properties of carbon nanomaterials and carbon containing metal hydrides

Energy Technology Data Exchange (ETDEWEB)

Maehlen, Jan Petter

2003-07-01

The topic of this thesis is structural investigations of carbon containing materials in respect to their hydrogen storage properties. This work was initially triggered by reports of extremely high hydrogen storage capacities of specific carbon nanostructures. It was decided to try to verify and understand the mechanisms in play in case of the existence of such high hydrogen densities in carbon. Two different routes towards the goal were employed; by studying selected hydrides with carbon as one of its constituents (mainly employing powder diffraction techniques in combination with hydrogen absorption and desorption measurements) and by carefully conducting hydrogen sorption experiments on what was believed to be the most ''promising'' carbon nanomaterial sample. In the latter case, a lot of effort was attributed to characterisations of different carbon nanomaterial containing samples with the aid of electron microscopy. Three different carbon-containing metal hydride systems, Y2C-H, YCoC-H and Y5SiC0.2-H, were examined. A relation between hydrogen occupation and the local arrangement of metal and carbon atoms surrounding the hydrogen sites was established. Several characteristic features of the compounds were noted in addition to solving the structure of the former unknown deuterideY5Si3C0.2D2.0 by the use of direct methods. Several carbon-nanomaterial containing samples were studied by means of transmission electron microscopy and powder diffraction, thus gaining knowledge concerning the structural aspects of nanomaterials. Based on these investigations, a specific sample containing a large amount of open-ended single-wall carbon nanotubes was chosen for subsequent hydrogen storage experiments. The latter experiments revealed moderate hydrogen storage capacities of the nanotubes not exceeding the values obtained for more conventional forms of carbon. These two different routes in investigating the hydrogen storage properties of carbon and

Hydrogen adsorption on bimetallic PdAu(111) surface alloys

DEFF Research Database (Denmark)

Takehiro, Naoki; Liu, Ping; Bergbreiter, Andreas

2014-01-01

The adsorption of hydrogen on structurally well defined PdAu-Pd(111) monolayer surface alloys was investigated in a combined experimental and theoretical study, aiming at a quantitative understanding of the adsorption and desorption properties of individual PdAu nanostructures. Combining...... the structural information obtained by high resolution scanning tunneling microscopy (STM), in particular on the abundance of specific adsorption ensembles at different Pd surface concentrations, with information on the adsorption properties derived from temperature programmed desorption (TPD) spectroscopy...... and high resolution electron energy loss spectroscopy (HREELS) provides conclusions on the minimum ensemble size for dissociative adsorption of hydrogen and on the adsorption energies on different sites active for adsorption. Density functional theory (DFT) based calculations give detailed insight...

Hydrogen absorption/desorption properties in the TiCrV based alloys

Directory of Open Access Journals (Sweden)

A. Martínez

2012-10-01

Full Text Available Three different Ti-based alloys with bcc structure and Laves phase were studied. The TiCr1.1V0.9, TiCr1.1V0.45Nb0.45 and TiCr1.1V0.9 + 4%Zr7Ni10 alloys were melted in arc furnace under argon atmosphere. The hydrogen absorption capacity was measured by using aparatus type Sievert's. Crystal structures, and the lattice parameters were determined by using X-ray diffraction, XRD. Microestructural analysis was performed by scanning electron microscope, SEM and electron dispersive X-ray, EDS. The hydrogen storage capacity attained a value of 3.6 wt. (% for TiCr1.1V0.9 alloy in a time of 9 minutes, 3.3 wt. (% for TiCr1.1V0.45Nb0.45 alloy in a time of 7 minutes and 3.6 wt. (% TiCr1.1V0.9 + 4%Zr7Ni10 with an increase of the hydrogen absorption kinetics attained in 2 minutes. This indicates that the addition of Nb and 4%Zr7Ni10 to the TiCrV alloy acts as catalysts to accelerate the hydrogen absorption kinetics.

Analysis of the technique Thermal Desorption Spectroscopy (TDS) and its Application for the Characterization of Metal -Hydrogen Systems; Analisis de la Tecnica Espectroscopia de Desorcion Termica (TDS) y su Applicacion para la Caracterizacion de Sistemas Metal-Hydrogeno

Energy Technology Data Exchange (ETDEWEB)

Castro, F J [Comision Nacional de Energia Atomica, Centro Atomico Bariloche (Argentina)

2000-07-01

limiting step is the recombination of two hydrogen atoms on the surface of the material. When the surface of the sample is in the a phase (solid solution) the rate limiting step is one of the processes that occurs on the surface of the material: the transfer of a hydrogen atom from the bulk to the surface or the recombination and desorption on the surface. By fitting the spectra we obtain an activation energy equal to 31 n 6 kJ/mol for the b phase, and equal to 35 n 3 kJ/mol for the a phase. We also compare the spectra of the powder with the spectra of the granules, foils and wires. Based on this comparison we analyze the effect on the desorption spectra of the characteristic size and geometry of the samples.Finally, we present a study of hydrogen desorption in the Pd-H system poisoned with sulfur. The poisoning produces as main effects a delay of the absorption and desorption processes without any appreciable loss in the storage capacity of the material.The experimental apparatus and theoretical models developed have been applied to the study of a MH system using samples with different morphology, characteristic size, geometry and surface state. The spectra were measured for different hydrogen concentrations and heating speeds. The results obtained encourage the utilization of TDS for the study and characterization of hydrogen desorption in MH systems. The technique is suited for the detailed analysis of the physical properties of the system and for the qualitative evaluation of the kinetic processes and their possible influence on technological devices.

Structure and hydrogen storage properties of the hexagonal Laves phase Sc(Al{sub 1-x}Ni{sub x}){sub 2}

Energy Technology Data Exchange (ETDEWEB)

Sahlberg, Martin, E-mail: Martin.sahlberg@kemi.uu.se [Department of Chemistry, The Angstroem Laboratory, Uppsala University, Box 538, SE-751 21 Uppsala (Sweden); Angstroem, Jonas, E-mail: jonas.angstrom@kemi.uu.se [Department of Chemistry, The Angstroem Laboratory, Uppsala University, Box 538, SE-751 21 Uppsala (Sweden); Zlotea, Claudia, E-mail: claudia.zlotea@icmpe.cnrs.fr [Chimie Metallurgique des Terres Rares, Institut de Chimie et des Materiaux de Paris Est, UMR 7182, CNRS, 2-8 rue Henri Dunant, 94320 Thiais Cedex (France); Beran, Premysl, E-mail: pberan@ujf.cas.cz [Nuclear Physics Institute, Academy of Sciences of the Czech Republic, 25068 Rez (Czech Republic); Latroche, Michel, E-mail: michel.latroche@glvt-cnrs.fr [Chimie Metallurgique des Terres Rares, Institut de Chimie et des Materiaux de Paris Est, UMR 7182, CNRS, 2-8 rue Henri Dunant, 94320 Thiais Cedex (France); Pay Gomez, Cesar, E-mail: Cesar.paygomez@kemi.uu.se [Department of Chemistry, The Angstroem Laboratory, Uppsala University, Box 538, SE-751 21 Uppsala (Sweden)

2012-12-15

The crystal structures of hydrogenated and unhydrogenated Sc(Al{sub 1-x}Ni{sub x}){sub 2} Laves phases have been studied by combining several diffraction techniques and it is shown that hydrogen is situated interstitially in the A{sub 2}B{sub 2}-sites, which have the maximum number of scandium neighbours. The hydrogen absorption/desorption behaviour has also been investigated. It is shown that a solid solution of hydrogen forms in the mother compound. The hydrogen storage capacity exceeds 1.7 H/f.u. at 374 K, and the activation energy of hydrogen desorption was determined to 4.6 kJ/mol H{sub 2}. It is shown that these compounds share the same local coordination as Frank-Kasper-type approximants and quasicrystals, which opens up the possibility of finding many new hydride phases with these types of crystal structures. - Graphical abstract: The structure of ScNiAlDx, Sc atoms are shown in purple and Ni/Al atoms in blue and the iso-surfaces of deuterium in yellow. Revealed from refinements of neutron powder diffraction data. Highlights: Black-Right-Pointing-Pointer The crystal structure of ScNiAl and ScNiAlDx is reported. Black-Right-Pointing-Pointer We show the hydrogen storage properties of Sc(Al{sub 1-x}Ni{sub x}){sub 2}. Black-Right-Pointing-Pointer We discuss the possibility to store hydrogen in quasicrystals.

Effects of buffer agents on hydrogen adsorption and desorption at/within activated carbon for the negative electrode of aqueous asymmetric supercapacitors

International Nuclear Information System (INIS)

Chien, Hsiu-Chuan; Wu, Tzu-Ho; Rajkumar, Muniyandi; Hu, Chi-Chang

2016-01-01

Highlights: • H adsorption causes local pH increase and negatively shifts the double-layer potential window. • The local pH variation at AC/electrolyte interface can be controlled via adding buffer agents. • H adsorption potential on AC in buffer electrolytes follows the Nernstian dependence. • The pseudocapacitive reversibility of H adsorption/desorption at/within AC is too poor. - Abstract: In this work, the effects of adding buffer agents into aqueous electrolytes on the hydrogen adsorption/desorption behaviour at/within activated carbon are systematically investigated for the negative electrode of asymmetric supercapacitors. Due to the poor electrochemical reversibility of hydrogen adsorption/desorption at/within activated carbon, the hydrogen responses at/within activated carbon are not suitable for pseudo-capacitive energy storage of high-performance asymmetric supercapacitor. The electrochemical adsorption of H atoms consumes protons and causes the local pH change at the activated carbon/electrolyte interface, leading to the negative shift in the H adsorption potential when weakly acidic, neutral, and weakly basic electrolytes without buffer agents are employed. The addition of buffer agents into electrolytes significantly improves the rate of proton supply and promotes the rate of hydrogen adsorption at/within AC. Interestingly, the onset potential of significant H adsorption obtained from the buffered electrolytes generally follows the Nernstian dependence, suggesting the Nerstian dependence of H"+/H_a_d_s on AC at all pH values. In order to obtain the energy storage devices with high coulombic and energy efficiencies, the onset potential of significant H adsorption obtained from the electrolyte containing buffer agents is a reliable lower potential limit of the AC-coated negative electrode for aqueous asymmetric supercapacitors.

Fundamental study of hydrogen-attachment-induced peptide fragmentation occurring in the gas phase and during the matrix-assisted laser desorption/ionization process.

Science.gov (United States)

Asakawa, Daiki; Takahashi, Hidenori; Iwamoto, Shinichi; Tanaka, Koichi

2018-05-09

Mass spectrometry with hydrogen-radical-mediated fragmentation techniques has been used for the sequencing of proteins/peptides. The two methods, matrix-assisted laser desorption/ionization in-source decay (MALDI-ISD) and hydrogen attachment/abstraction dissociation (HAD) are known as hydrogen-radical-mediated fragmentation techniques. MALDI-ISD occurs during laser induced desorption processes, whereas HAD utilizes the association of hydrogen with peptide ions in the gas phase. In this study, the general mechanisms of MALDI-ISD and HAD of peptides were investigated. We demonstrated the fragmentation of four model peptides and investigated the fragment formation pathways using density functional theory (DFT) calculations. The current experimental and computational joint study indicated that MALDI-ISD and HAD produce aminoketyl radical intermediates, which immediately undergo radical-induced cleavage at the N-Cα bond located on the C-terminal side of the radical site, leading to the c'/z˙ fragment pair. In the case of MALDI-ISD, the z˙ fragments undergo a subsequent reaction with the matrix to give z' and matrix adducts of the z fragments. In contrast, the c' and z˙ fragments react with hydrogen atoms during the HAD processes, and various fragment species, such as c˙, c', z˙ and z', were observed in the HAD-MS/MS mass spectra.

Study of Supported Nickel Catalysts Prepared by Aqueous Hydrazine Method. Hydrogenating Properties and Hydrogen Storage: Support Effect. Silver Additive Effect

International Nuclear Information System (INIS)

Wojcieszak, R.

2006-06-01

We have studied Ni or NiAg nano-particles obtained by the reduction of nickel salts (acetate or nitrate) by hydrazine and deposited by simple or EDTA-double impregnation on various supports (γ-Al 2 O 3 , amorphous or crystallized SiO 2 , Nb 2 O 5 , CeO 2 and carbon). Prepared catalysts were characterized by different methods (XRD, XPS, low temperature adsorption and desorption of N 2 , FTIR and FTIR-Pyridine, TEM, STEM, EDS, H 2 -TPR, H 2 -adsorption, H 2 -TPD, isopropanol decomposition) and tested in the gas phase hydrogenation of benzene or as carbon materials in the hydrogen storage at room temperature and high pressure. The catalysts prepared exhibited better dispersion and activity than classical catalysts. TOF's of NiAg/SiO 2 or Ni/carbon catalysts were similar to Pt catalysts in benzene hydrogenation. Differences in support acidity or preparation method and presence of Ag as metal additive play a crucial role in the chemical reduction of Ni by hydrazine and in the final properties of the materials. Ni/carbon catalysts could store significant amounts of hydrogen at room temperature and high pressure (0.53%/30 bars), probably through the hydrogen spillover effect. (author)

Oxygen Sorption and Desorption Properties of Selected Lanthanum Manganites and Lanthanum Ferrite Manganites

DEFF Research Database (Denmark)

Nielsen, Jimmi; Skou, Eivind M.; Jacobsen, Torben

2015-01-01

Temperature‐programmed desorption (TPD) with a carrier gas was used to study the oxygen sorption and desorption properties of oxidation catalysts and solid‐oxide fuel cell (SOFC) cathode materials (La0.85Sr0.15)0.95MnO3+δ (LSM) and La0.60Sr0.40Fe0.80Mn0.20O3‐δ (LSFM). The powders were characterized...... by X‐ray diffractometry, atomic force microscopy (AFM), and BET surface adsorption. Sorbed oxygen could be distinguished from oxygen originating from stoichiometry changes. The results indicated that there is one main site for oxygen sorption/desorption. The amount of sorbed oxygen was monitored over...... time at different temperatures. Furthermore, through data analysis it was shown that the desorption peak associated with oxygen sorption is described well by second‐order desorption kinetics. This indicates that oxygen molecules dissociate upon adsorption and that the rate‐determining step...

A new ternary magnesium-titanium hydride Mg{sub 7}TiH{sub x} with hydrogen desorption properties better than both binary magnesium and titanium hydrides

Energy Technology Data Exchange (ETDEWEB)

Kyoi, Daisuke; Sato, Toyoto; Roennebro, Ewa; Kitamura, Naoyuki; Ueda, Atsushi; Ito, Mikio; Katsuyama, Shigeru; Hara, Shigeta; Noreus, Dag; Sakai, Tetsuo

2004-06-09

A magnesium based titanium doped hydride was prepared in a high-pressure anvil cell by reacting a mixture of MgH{sub 2} and TiH{sub 1.9} at 8 GPa and 873 K. The metal structure has a Ca{sub 7}Ge type structure (a=9.532(2) A, space group Fm3-barm (no. 225), Z=4, V=866.06 A{sup 3}). The refined metal atom composition Mg{sub 7}Ti was almost in line with EDS analysis. This means that the new magnesium-titanium hydride has a structure that is more related to TiH{sub 1.9} than to MgH{sub 2}. The thermal properties of the new compound were also studied by TPD analysis. The new hydride, Mg{sub 7}TiH{sub x} exhibits 5.5 mass% (x{approx}12.7) and decomposes into Mg and TiH{sub 1.9} upon releasing 4.7 mass% of hydrogen around 605 K, that is at a 130 and 220 K lower desorption temperature compared to MgH{sub 2} and TiH{sub 1.9}, respectively.

Recyclable hydrogen storage system composed of ammonia and alkali metal hydride

Energy Technology Data Exchange (ETDEWEB)

Yamamoto, Hikaru [Department of Quantum Matter, AdSM, Hiroshima University, 1-3-1 Kagamiyama, Higashi-Hiroshima, Hiroshima 739-8530 (Japan); Miyaoka, Hiroki; Hino, Satoshi [Institute for Advanced Materials Research, Hiroshima University, 1-3-1 Kagamiyama, Higashi-Hiroshima, Hiroshima 739-8530 (Japan); Nakanishi, Haruyuki [Higashi-Fuji Technical Center, Toyota Motor Corporation, 1200 Misyuku, Susono, Shizuoka 410-1193 (Japan); Ichikawa, Takayuki; Kojima, Yoshitsugu [Department of Quantum Matter, AdSM, Hiroshima University, 1-3-1 Kagamiyama, Higashi-Hiroshima, Hiroshima 739-8530 (Japan); Institute for Advanced Materials Research, Hiroshima University, 1-3-1 Kagamiyama, Higashi-Hiroshima, Hiroshima 739-8530 (Japan)

2009-12-15

Ammonia (NH{sub 3}) reacts with alkali metal hydrides MH (M = Li, Na, and K) in an exothermic reaction to release hydrogen (H{sub 2}) at room temperature, resulting that alkali metal amides (MNH{sub 2}) which are formed as by-products. In this work, hydrogen desorption properties of these systems and the condition for the recycle from MNH{sub 2} back to MH were investigated systematically. For the hydrogen desorption reaction, the reactivities of MH with NH{sub 3} were better following the atomic number of M on the periodic table, Li < Na < K. It was confirmed that the hydrogen absorption reaction of all the systems proceeded under 0.5 MPa of H{sub 2} flow condition below 300 C. (author)

Phase Transformation and Hydrogen Storage Properties of an La7.0Mg75.5Ni17.5 Hydrogen Storage Alloy

Directory of Open Access Journals (Sweden)

Lin Hu

2017-10-01

Full Text Available X-ray diffraction showed that an La7.0Mg75.5Ni17.5 alloy prepared via inductive melting was composed of an La2Mg17 phase, an LaMg2Ni phase, and an Mg2Ni phase. After the first hydrogen absorption/desorption process, the phases of the alloy turned into an La–H phase, an Mg phase, and an Mg2Ni phase. The enthalpy and entropy derived from the van’t Hoff equation for hydriding were −42.30 kJ·mol−1 and −69.76 J·K−1·mol−1, respectively. The hydride formed in the absorption step was less stable than MgH2 (−74.50 kJ·mol−1 and −132.3 J·K−1·mol−1 and Mg2NiH4 (−64.50 kJ·mol−1 and −123.1 J·K−1·mol−1. Differential thermal analysis showed that the initial hydrogen desorption temperature of its hydride was 531 K. Compared to Mg and Mg2Ni, La7.0Mg75.5Ni17.5 is a promising hydrogen storage material that demonstrates fast adsorption/desorption kinetics as a result of the formation of an La–H compound and the synergetic effect of multiphase.

Thermal stability of hydrogenated small-diameter carbon nanotubes

Energy Technology Data Exchange (ETDEWEB)

Podlivaev, A. I., E-mail: AIPodlivayev@mephi.ru; Openov, L. A. [National Research Nuclear University “MEPhI” (Russian Federation)

2017-02-15

The initial stage of hydrogen desorption from fully hydrogenated carbon nanotubes (3.0) and (2.2) is numerically studied by the molecular dynamics method. The temperature dependence of the desorption rate is directly determined at T = 1800–2500 K. The characteristic desorption times are determined at temperatures outside this range by extrapolation. It is shown that hydrogen desorption leads to the appearance of electronic states in the band gap.

Hydrogen storage properties in the Mg_0_._7_5Ta_0_._2_5 system prepared by mechanical milling

International Nuclear Information System (INIS)

Ramirez G, J. A.

2016-01-01

Magnesium and most of its mixtures have slow sorption-desorption kinetics of hydrogen, which limits their technological application and their viability from the economic view point. Recently, has been observed that by the synthesis of advanced materials, using the mechanical milling technique, positive changes in the kinetics are introduced. In order to improve the sorption-desorption hydrogen properties, in the present work a mixture consisting of Mg_0_._7_5Ta_0_._2_5 was prepared using methanol as process control agent. To this end, the first methodological step was to carry out, by means of the mechanical milling technique, the synthesis of the mixture Mg_0_._7_5Ta_0_._2_5 in a Spex type vibratory mill at times of 6, 12, 18 and 24 h. Subsequently, the material was characterized by different analytical techniques such as scanning electron microscopy with elemental analysis, X-ray diffraction and N_2 physisorption analysis. Subsequently, hydrogen sorption experiments were carried out in a Parr reactor to evaluate the hydrogen storage capacity of the mixture, varying temperature parameters, pressure and time, in order to determine the optimal parameters of hydrogen sorption. The characterization of the hydrogen storage capacity was analyzed by the thermogravimetric analysis/differential scanning calorimetry technique coupled to a mass spectrometer. X ray diffraction analysis reveals that there is a mixture between the starting compounds, with an important refinement of the microstructure as a consequence of the mechanical milling process. The results of the hydrogen sorption tests at 1, 5 and 10 cycles showed that the storage of hydrogen in the Mg_0_._7_5Ta_0_._2_5 mixture can be carried out at a temperature of 25 degrees Celsius with a pressure of 2 atm and a contact time of 1 h. (Author)

Site Specificity in Femtosecond Laser Desorption of Neutral H Atoms from Graphite(0001)

DEFF Research Database (Denmark)

Frigge, R.; Hoger, T.; Siemer, B.

2010-01-01

Femtosecond laser excitation and density functional theory reveal site and vibrational state specificity in neutral atomic hydrogen desorption from graphite induced by multiple electronic transitions. Multimodal velocity distributions witness the participation of ortho and para pair states...... of chemisorbed hydrogen in the desorption process. Very slow velocities of 700 and 400  ms-1 for H and D atoms are associated with the desorption out of the highest vibrational state of a barrierless potential....

Electrocatalytic activity of a mononuclear yttrium(III)–methyl orange complex and Y{sub 2}O{sub 2}SO{sub 4} nanoparticles for adsorption/desorption of hydrogen

Energy Technology Data Exchange (ETDEWEB)

Shafaie, Fahimeh [Department of Chemistry, Isfahan University of Technology, Isfahan, 84156-83111 (Iran, Islamic Republic of); Hadadzadeh, Hassan, E-mail: hadad@cc.iut.ac.ir [Department of Chemistry, Isfahan University of Technology, Isfahan, 84156-83111 (Iran, Islamic Republic of); Behnamfar, Mohammad Taghi [Department of Chemistry, Isfahan University of Technology, Isfahan, 84156-83111 (Iran, Islamic Republic of); Rudbari, Hadi Amiri [Faculty of Chemistry, University of Isfahan, Isfahan, 81746-73441 (Iran, Islamic Republic of)

2016-12-01

A new mononuclear yttrium(III) complex, [Y(MO){sub 3}(DMF){sub 3}(H{sub 2}O){sub 2}] (where MO{sup –} is methyl orange anion (4-[(4-dimethylamino)phenyldiazenyl]benzenesulfonate)), was synthesized in an aqueous solution. The complex was characterized by elemental analysis, UV/Vis, FT-IR, and single-crystal X-ray crystallography. The yttrium oxysulfate nanoparticles (Y{sub 2}O{sub 2}SO{sub 4}) were then prepared by calcination of [Y(MO){sub 3}(DMF){sub 3}(H{sub 2}O){sub 2}]. The obtained nanoparticles were characterized by FT-IR, X-ray diffraction analysis (XRD), and field-emission scanning electron microscopy (FE-SEM). The hydrogen adsorption/desorption (H{sub ads}/H{sub des}) behavior of the Y(III) complex and Y{sub 2}O{sub 2}SO{sub 4} nanoparticles was studied at a carbon paste electrode (CPE) in H{sub 2}SO{sub 4} by cyclic voltammetry (CV). The recorded voltammograms exhibited a pair of peaks corresponding to the adsorption/desorption of hydrogen for the Y(III) complex and Y{sub 2}O{sub 2}SO{sub 4} nanoparticles. The results show a reversible hydrogen adsorption/desorption reaction for both compounds. The voltammograms of the nanoparticles indicate an excellent cycling stability for the adsorption/desorption of hydrogen. In addition, the linear sweep voltammetry (LSV) technique was used to investigate the electrocatalytic activity of both compounds for the hydrogen adsorption reaction. The linear voltammograms of both compounds demonstrate the excellent electrocatalytic activity for the hydrogen adsorption reaction. - Highlights: • Preparation of a new Y(III) complex and Y{sub 2}O{sub 2}SO{sub 4} nanoparticles. • Investigation of the H{sub ads}/H{sub des} reaction for both compounds by voltammetry. • Observation of two peaks corresponding to the H{sub ads}/H{sub des} in both compounds. • An excellent cycling stability for the nanoparticles in H{sub 2}SO{sub 4}.

Hydrogen adsorption and desorption in carbon nanotube systems and its mechanisms

Energy Technology Data Exchange (ETDEWEB)

Shiraishi, M.; Takenobu, T.; Ata, M. [Materials Laboratories, SONY Corporation, Shin-Sakuragaoka 2-1-1, Hodogaya-ku, 240-0036, Yokohama (Japan); Kataura, H. [Department of Physics, Faculty of Science, Tokyo Metropolitan University, Minami-Osawa, Hachioji, 192-0397, Tokyo (Japan)

2004-04-01

The hydrogen physisorption properties in single-walled carbon nanotube (SWNT) based materials were characterized. The SWNTs were highly purified and three useful pores for hydrogen physisorption were activated. Hydrogen was physisorbed in intra-tube pores at room temperature and the capacity was estimated to be about 0.3-0.4 wt. % at room temperature. The adsorption capacity can be explained by the Langmuir model. The intra-tube pores have large adsorption potential and this induces hydrogen physisorption at comparatively higher temperatures. This fact indicates the importance of fabricating sub-nanometer ordered pores for this phenomena. (orig.)

Hydrogen storage behavior of ZrCo1-xNix alloys

International Nuclear Information System (INIS)

Jat, Ram Avtar; Parida, S.C.; Agarwal, Renu; Kulkarni, S.G.

2012-01-01

Intermetallic compound ZrCo is proposed as a candidate material for storage, supply and recovery of hydrogen isotopes in International Thermonuclear Experimental Reactor (ITER) Storage and Delivery System (SDS). However, it has been reported that upon repeated hydriding-dehydriding cycles, ZrCo undergoes disproportionation as per the reaction; 2ZrCo + H 2 ↔ ZrH 2 + ZrCO 2 . This results in reduction in hydrogen storage capacity of ZrCo, which is not a desirable property for SDS. Konishi et al. reported that the disproportionation reaction can be suppressed by decreasing the desorption temperature. It is anticipated that suitable ternary alloying of ZrCo can elevated the hydrogen equilibrium pressure and hence decrease the desorption temperature for supply of 100 kPa of hydrogen. In this study, we have investigated the effect of Ni content on the hydrogenation behavior of ZrCo 1-x Ni x alloys

Hydriding properties of amorphous Ni-B alloy studied by DSC and thermogravimetry

International Nuclear Information System (INIS)

Spassov, T.; Rangelova, V.

1999-01-01

The hydrogenation behaviour of melt-spun Ni 81.5 B 18.5 amorphous alloy was studied by means of differential scanning calorimetry (DSC) and thermogravimetry (TG) and compared with the hydriding properties of a Fe-B-Si glass. It was found that the amorphous Ni-B alloy absorbs larger amounts of hydrogen than the Fe-B-Si glass, as the initial kinetics of hydrogen absorption and desorption of both the alloys are comparable. Hydrogen absorption and desorption reactions in Ni-B were observed to proceed with similar rates at ca. 300 K. The hydrogen desorption is revealed in DSC as an endothermic peak in the 350-450 K range, preceding the crystallization peak of the amorphous alloy. The enthalpy of hydrogen desorption (ΔH des =22 kJ/mol H 2 ) for Ni-B was found to be smaller than that for the Fe-B-Si glass, which finding is in contrast to the results on hydrogen diffusion in crystalline αFe and Fe-based alloys and Ni and Ni-based alloys. The hydrogen desorption temperature and enthalpy for Ni 81.5 B 18.5 were found to be independent of the amount of hydrogen absorbed. (Copyright (c) 1999 Elsevier Science B.V., Amsterdam. All rights reserved.)

Ultrapure hydrogen thermal compressor based on metal hydrides for fuel cells and hybrid vehicles

International Nuclear Information System (INIS)

Almasan, V.; Biris, A.; Coldea, I.; Lupu, D.; Misan, I.; Popeneciu, G.; Ardelean, O.

2007-01-01

Full text: In hydrogen economy, efficient compressors are indispensable elements in the storage, transport and distribution of the produced hydrogen. Energetic efficient technologies can contribute to H 2 pipelines transport to the point of use and to distribute H 2 by refuelling stations. Characteristic for metal hydrides systems is the wide area of possibilities to absorb hydrogen at low pressure from any source of hydrogen, to store and deliver it hydrogen at high pressure (compression ratio more than 30). On the basis of innovative concepts and advanced materials for H 2 storage/compression (and fast thermal transfer), a fast mass (H 2 ) and heat transfer unit will be developed suitable to be integrated in a 3 stage thermal compressor. Metal hydrides used for a three stage hydrogen compression system must have different equilibrium pressures, namely: for stage 1, low pressure H 2 absorption and resistant to poisoning with impurities of hydrogen, for stage 2, medium pressure H 2 absorption and for stage 3, high pressure hydrogen delivery (120 bar). In the case of compression device based on metallic hydrides the most important properties are the hydrogen absorption/desorption rate, a smaller process enthalpy and a great structural stability on long term hydrogen absorption/desorption cycling. These properties require metal hydrides with large differences between the hydrogen absorption and desorption pressures at equilibrium, within a rather small temperature range. The main goal of this work is to search and develop metal hydride integrated systems for hydrogen purification, storage and compression. After a careful screening three hydrogen absorbing alloys will be selected. After selection, the work up of the alloys composition on the bases of detailed solid state studies, new multi-component alloys will be developed, with suitable thermodynamic and kinetic properties for a hydrogen compressor. The results of the study are the following: new types of hydrogen

Hydrogenation-disproportionation-desorption-recombination in Sm2Fe16M (M=Al, Ga and Si) and magnetic properties of their carburized powders

International Nuclear Information System (INIS)

Kubis, M.; Rave, W.; Cao, L.; Gebel, B.; Mueller, K.-H.; Schultz, L.

1998-01-01

The application of the hydrogenation-disproportionation-desorption-recombination (HDDR) process in Sm 2 Fe 16 M (M=Al,Ga and Si) was investigated. The hydrogen absorption behaviour was studied by temperature-pressure analysis (TPA). In the temperature range between 500 and 800 C, Sm 2 Fe 16 M samples with M=Ga and Si show a weaker hydrogen absorption than Sm 2 Fe 16 Al. This was confirmed by X-ray diffraction which showed a complete disproportionation of Sm 2 Fe 16 Al into SmH z (1.9 2 Fe 16 Ga and Sm 2 Fe 16 Si exhibit a fraction of undecomposed material with the Th 2 Zn 17 -type structure after the disproportionation procedure. These results point to a stabilization of Sm 2 Fe 16 M against disproportionation by hydrogen for M=Ga and Si. The magnetization processes of carburized HDDR powders were studied by VSM measurements and Kerr microscopy. The demagnetization curve of our HDDR processed Sm 2 Fe 16 AlC y is well shaped, whereas those of Sm 2 Fe 16 GaC y and Sm 2 Fe 16 SiC y show a large decrease of the polarization at low fields. The favourable behaviour of Sm 2 Fe 16 AlC y is due to a homogeneous submicron grain structure. In Sm 2 Fe 16 GaC y and Sm 2 Fe 16 SiC y samples, an additional, magnetically soft phase with larger domains was observed which causes the low coercivity. As a consequence, HDDR was only favourable for the preparation of Sm 2 Fe 16 MC y hard magnets with M=Al but not for M=Ga and Si. Optimization of the HDDR process in Sm 2 Fe 16 Al and subsequent nitrogenation or carburization led to coercivities of μ 0j H c =2.9 and 2.5 T, respectively. (orig.)

The Effects of Added Hydrogen on Noble Gas Discharges Used as Ambient Desorption/Ionization Sources for Mass Spectrometry

Science.gov (United States)

Ellis, Wade C.; Lewis, Charlotte R.; Openshaw, Anna P.; Farnsworth, Paul B.

2016-09-01

We demonstrate the effectiveness of using hydrogen-doped argon as the support gas for the dielectric barrier discharge (DBD) ambient desorption/ionization (ADI) source in mass spectrometry. Also, we explore the chemistry responsible for the signal enhancement observed when using both hydrogen-doped argon and hydrogen-doped helium. The hydrogen-doped argon was tested for five analytes representing different classes of molecules. Addition of hydrogen to the argon plasma gas enhanced signals for gas-phase analytes and for analytes coated onto glass slides in positive and negative ion mode. The enhancements ranged from factors of 4 to 5 for gas-phase analytes and factors of 2 to 40 for coated slides. There was no significant increase in the background. The limit of detection for caffeine was lowered by a factor of 79 using H2/Ar and 2 using H2/He. Results are shown that help explain the fundamental differences between the pure-gas discharges and those that are hydrogen-doped for both argon and helium. Experiments with different discharge geometries and grounding schemes indicate that observed signal enhancements are strongly dependent on discharge configuration.

Moisture sorption–desorption characteristics and the corresponding thermodynamic properties of carvedilol phosphate

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Ravikiran Allada

2017-01-01

Full Text Available Aims: Carvedilol phosphate (CDP is a nonselective beta-blocker used for the treatment of heart failures and hypertension. In this work, moisture sorption–desorption characteristics and thermodynamic properties of CDP have been investigated. Materials and Methods: The isotherms were determined using dynamic vapor sorption analyzer at different humidity conditions (0%–90% relative humidity and three pharmaceutically relevant temperatures (20°C, 30°C, and 40°C. The experimental sorption data determined were fitted to various models, namely, Brunauer–Emmett–Teller; Guggenheim-Anderson-De Boer (GAB; Peleg; and modified GAB. Isosteric heats of sorption were evaluated through the direct use of sorption isotherms by means of the Clausius-Clapeyron equation. Statistical Analysis Used: The sorption model parameters were determined from the experimental sorption data using nonlinear regression analysis, and mean relative percentage deviation (P, correlation (Correl, root mean square error, and model efficiency were considered as the criteria to select the best fit model. Results: The sorption–desorption isotherms have sigmoidal shape – confirming to Type II isotherms. Based on the statistical data analysis, modified GAB model was found to be more adequate to explain sorption characteristics of CDP. It is noted that the rate of adsorption and desorption is specific to the temperature at which it was being studied. It is observed that isosteric heat of sorption decreased with increasing equilibrium moisture content. Conclusions: The calculation of the thermodynamic properties was further used to draw an understanding of the properties of water and energy requirements associated with the sorption behavior. The sorption–desorption data and the set of equations are useful in the simulation of processing, handling, and storage of CDP and further behavior during manufacture and storage of CDP formulations.

Actuation of Pneumatic Artificial Muscle via Hydrogen Absorption/Desorption of Metal Hydride-LaNi5

Directory of Open Access Journals (Sweden)

Thanana Nuchkrua

2015-01-01

Full Text Available This paper presents experimental studies on mechanical actuations of a pneumatic artificial muscle (PAM, which is driven by hydrogen gas based metal hydride (MH. The dynamic performances of hydrogen absorption/desorption, taking place within a MH reactor, are controlled via implementing cooling/heating effects of a thermoelectric module (TEM. Hydrogen pressure is applied as a driving force to commanding work outputs of the PAM as desired mechanical actuations. Due to strong inherent nonlinearity, a conventional proportional integral derivative (PID control law is not capable of regulating thermodynamic variables of the HM reaction according to desired performances of the PAM. In this study, the fuzzy adaptive PID control is proposed in manipulating the MH reaction via the TEM. This viability of the proposed methodology is confirmed by the fact that the gains of PID control law are adapted by fuzzy rule-based tuning scheme at various operating conditions of the MH reactor. The experimental results show that the proposed control technique is much more effective than a PID control in both transient and steady state performances of the MH reactor for servo mechanical actuation of the PAM.

Phase transition and hydrogen storage properties of Mg–Ga alloy

International Nuclear Information System (INIS)

Wu, Daifeng; Ouyang, Liuzhang; Wu, Cong; Wang, Hui; Liu, Jiangwen; Sun, Lixian; Zhu, Min

2015-01-01

Highlights: • A fully reversible transformation in Mg–Ga–H system with reduced dehydrogenation enthalpy is realized. • The mechanism of phase transformation in the de/hydrogenation of Mg–Ga alloy is revealed. • The de/hydrogenation process of Mg 5 Ga 2 compound is expressed as: Mg 5 Ga 2 + H 2 ↔ 2Mg 2 Ga + MgH 2 . - Abstract: Mg-based alloys are viewed as one of the most promising candidates for hydrogen storage; however, high desorption temperature and the sluggish kinetics of MgH 2 hinder their practical application. Alloying and changing the reaction pathway are effective methods to solve these issues. As the solid solubility of Ga in Mg is 5 wt% at 573 K, the preparation of a Mg(Ga) solid solution at relatively high temperatures was designed in this paper. The phase transition and hydrogen storage properties of the MgH 2 and Mg 5 Ga 2 composite (hereafter referred to as Mg–Ga alloy) were investigated by X-ray diffraction (XRD), pressure–composition-isotherm (PCI) measurements, and differential scanning calorimetry (DSC). The reversible hydrogen storage capacity of Mg–Ga alloy is 5.7 wt% H 2 . During the dehydrogenation process of Mg–Ga alloy, Mg 2 Ga reacts with MgH 2 , initially releasing H 2 and forming Mg 5 Ga 2 ; subsequently, MgH 2 decomposes into Mg with further release of H 2 . The phase transition mechanism of the Mg 5 Ga 2 compound during the dehydrogenation process was also investigated by using in situ XRD analysis. In addition, the dehydrogenation enthalpy and entropy changes, and the apparent activation energy were also calculated

Hydrogen storage in complex hydrides

International Nuclear Information System (INIS)

Lupu, D.; Biris, A. R.; Misan, I.

2005-01-01

Full text: Hydrogen storage is a key enabling technology for the advancement of hydrogen and fuel cell power technologies in mobile and stationary applications. A relevant role of the fuel cell powered vehicles on the market of the transportation systems will be achieved only if the research and development of on-board vehicular hydrogen storage are able to allow a driving range of at least 500 km. The on-board hydrogen storage systems are more challenging due to the space, weight and cost limitations. This range of autonomy between refueling requires materials able to store at least 6.5% weight hydrogen, available at moderate pressures, at the working temperature of the fuel cells and with acceptable cycling stability. The intensive research on the hydrogen storage in alloys and intermetallic of the LaNi 5 , FeTi or Laves phase type compounds, which started more than three decades ago did not resulted in materials of more than about 3% H storage capacities. The 7.5% H content of the Mg hydride is still of attracting interest but though the absorption has been achieved at lower temperatures by ball milling magnesium with various amounts of nickel, the desorption can not be attained at 1 bar H 2 below 280 deg. C and the kinetics of the process is too slow. In the last decade, the attention is focused on another class of compounds, the complex hydrides of aluminum with alkali metals (alanates), due to their high hydrogen content. It was found that doping with Ti-based catalysts improve the hydrogenation/dehydrogenation conditions of NaAlH 4 . Later on, it was shown that ball milling with solid state catalysts greatly improve the hydrogen desorption kinetics of NaAlH 4 , and this also helps to the rehydriding process. The hydrogen desorption from NaAlH 4 occurs in three steps, it shows a reversible storage capacity of 5.5% H and this led to further research work for a better knowledge of its application relating properties. In this work, ball milling experiments on Na

Hydrogen isotope inventory in the graphite divertor tiles of ASDEX Upgrade as measured by thermal desorption spectroscopy

International Nuclear Information System (INIS)

Franzen, P.; Behrisch, R.; Garcia-Rosales, C.; Schleussner, D.; Roesler, D.; Becker, J.; Knapp, W.; Edelmann, C.

1997-01-01

The hydrogen and deuterium inventories of the ASDEX Upgrade divertor tiles were measured after the experimental period from December 1994 to July 1995 by thermal desorption spectroscopy (TDS) of samples cut out of the divertor tiles. The samples were heated by electron bombardment up to 2100 K; the released gases were measured by means of a calibrated quadrupole mass spectrometer. The measured hydrogen or deuterium inventories are of the order of 10 23 m -2 . They are larger for samples of the inner divertor than of the outer divertor by a factor of about 2. The largest inventory was found at the separatrix position of the inner divertor. Most of the released hydrogen (H) can be attributed to water adsorbed in the near surface region during the air exposure prior to the TDS measurements. The total inventories measured by TDS exceed the inventories in the near surface region (< 25 μm) measured by ion beam analysis methods by a factor of up to 10. Hence, the total hydrogen retention is governed by the diffusion out of the near surface region deep into the material. The hydrogen and deuterium inventories decreased with increasing surface temperature. (author). 64 refs, 12 figs, 2 tabs

Modeling and experimental verification of the thermodynamic properties of hydrogen storage materials

NARCIS (Netherlands)

Ledovskikh, A.V.; Danilov, D.L.; Vliex, M.F.H.; Notten, P.H.L.

2016-01-01

A new mathematical model has been developed describing the thermodynamics of the hydrogen absorption and desorption process in Metal Hydrides via the gas phase. This model is based on first principles chemical and statistical thermodynamics and takes into account structural changes occurring inside

Enhanced Hydrogen Storage Properties and Reversibility of LiBH4 Confined in Two-Dimensional Ti3C2.

Science.gov (United States)

Zang, Lei; Sun, Weiyi; Liu, Song; Huang, Yike; Yuan, Huatang; Tao, Zhanliang; Wang, Yijing

2018-05-30

LiBH 4 is of particular interest as one of the most promising materials for solid-state hydrogen storage. Herein, LiBH 4 is confined into a novel two-dimensional layered Ti 3 C 2 MXene through a facile impregnation method for the first time to improve its hydrogen storage performance. The initial desorption temperature of LiBH 4 is significantly reduced, and the de-/rehydrogenation kinetics are remarkably enhanced. It is found that the initial desorption temperature of LiBH 4 @2Ti 3 C 2 hybrid decreases to 172.6 °C and releases 9.6 wt % hydrogen at 380 °C within 1 h, whereas pristine LiBH 4 only releases 3.2 wt % hydrogen under identical conditions. More importantly, the dehydrogenated products can partially rehydrogenate at 300 °C and under 95 bar H 2 . The nanoconfined effect caused by unique layered structure of Ti 3 C 2 can hinder the particles growth and agglomeration of LiBH 4 . Meanwhile, Ti 3 C 2 could possess superior effect to destabilize LiBH 4 . The synergetic effect of destabilization and nanoconfinement contributes to the remarkably lowered desorption temperature and improved de-/rehydrogenation kinetics.

Effects of an electron beam on adsorption and desorption of ammonia on ruthenium (0001)

International Nuclear Information System (INIS)

Danielson, L.R.; Dresser, M.J.; Donaldson, E.E.; Sandstrom, D.R.

1978-01-01

The effects of an electron beam on ammonia adsorption and desorption on Ru(0001) have been investigated by Auger electron spectroscopy, low-energy electron diffraction, and thermal flash desorption. Appreciable adsorption at room temperature occurred only on the area of the Ru crystal which had been bombarded by an electron beam during dosing. The adsorption rate was a function of beam current density and ammonia pressure, and an apparent (2x2) diffraction pattern appeared in the area bombarded by the electron beam. Electron bombardment of the molecular γ states of ammonia followed by flash desorption showed that less ammonia and more hydrogen and nitrogen were desorbed as the bombardment time increased. An analysis of this process based on electron-induced dissociation of the ammonia molecule yielded an effective initial dissociation cross section of 3x10 -6 cm 2 . Hydrogen flash desorption spectra after bombardment of the γ states obeying first order kinetics with desorption energies of 0.78 and 1.0 eV. Electron bombardment of the γ states for short times produced the same effects on the ammonia flash desorption spectra as preadsorption of hydrogen. (Auth.)

Influence of the evaporation rate and the evaporation mode on the hydrogen sorption kinetics of air-exposed magnesium films

International Nuclear Information System (INIS)

Leon, A.; Knystautas, E.J.; Huot, J.; Schulz, R.

2006-01-01

It has been shown that the hydrogen sorption properties of air-exposed magnesium films are influenced by the deposition parameters such as the evaporation rate or the evaporation mode used during their preparation. As the evaporation rate increases, the structure of the film tends to be highly oriented along the [002] direction and the kinetics of hydrogen absorption and desorption are faster. Moreover, the hydrogen sorption kinetics of magnesium films prepared with an electron beam source under a high vacuum are faster by almost a factor of two compared to those prepared using resistive heating under low vacuum. These two parameters reduce drastically the activation and the incubation period during hydrogen absorption and desorption, respectively

Effect of Al in the H2 storage properties of Li-NH system

International Nuclear Information System (INIS)

Fernandez Albanesi, L; Lago, Marcelo N; Arneodo Larochette, P; Gennari, F.C

2012-01-01

In this work is studied the effect of the addition of aluminum on the properties of hydrogen absorption-desorption system LiNH 2 : 1,5 LiH. The samples were prepared adding the element Al to the system LiNH 2 :1.5 LiH in different ways (as aluminum metal, as aluminum chloride and as lithium aluminum hydride). In all these mixtures was maintained the concentration of Al in 1 mol%. A good distribution of Al is achieved by mechanical milling. Quantitative hydrogen absorption and desorption were measured by volumetric method with a Sieverts-type apparatus in the temperature range of 250 to 300 o C and 700 kPa of H 2 pressure. The systems with Al showed better absorption kinetics and greater stability after cycles of hydrogen absorption-desorption. The hydrogen capacity achieved by these samples was 5.3 wt% at 300 and 275 o C. The mixture with AlCl 3 displays the same characteristics at 250 o C, showing the better H 2 storage properties

The effect of TTNT nanotubes on hydrogen sorption using MgH2

Directory of Open Access Journals (Sweden)

Mariana Coutinho Brum

2013-06-01

Full Text Available Nanotubes are promising materials to be used with magnesium hydride, as catalysts, in order to enhance hydrogen sorption. A study was performed on the hydrogen absorption/desorption properties of MgH2 with the addition of TTNT (TiTanate NanoTubes. The MgH2-TTNT composite was prepared by ball milling and the influence of the TTNT amount (1.0 and 5.0 wt. (% on the hydrogen capacity was evaluated. The milling of pure MgH2 was performed for 24 hours and afterwards the MgH2-TTNT composite was milled for 20 minutes. Transmission Electronic Microscopy (TEM and Scanning Electron Microscopy (SEM were used to evaluate the nanotube synthesis and show the particle morphology of the MgH2-TTNT composite, respectively. The Differential Scanning Calorimetry (DSC examination provided some evidence with the shifting of the peaks obtained when the amount of TTNT is increased. The hydrogen absorption/desorption kinetics tests showed that the TTNT nanotubes can enhance hydrogen sorption effectively and the total hydrogen capacity obtained was 6.5 wt. (%.

The effect of TTNT nanotubes on hydrogen sorption using MgH2

International Nuclear Information System (INIS)

Brum, Mariana Coutinho; Jardim, Paula Mendes; Conceicao, Monique Osorio Talarico da; Santos, Dilson Silva dos

2013-01-01

Nanotubes are promising materials to be used with magnesium hydride, as catalysts, in order to enhance hydrogen sorption. A study was performed on the hydrogen absorption/desorption properties of MgH 2 with the addition of TTNT (TiTanate nanotubes). The MgH 2 -TTNT composite was prepared by ball milling and the influence of the TTNT amount (1.0 and 5.0 wt. (%)) on the hydrogen capacity was evaluated. The milling of pure MgH 2 was performed for 24 hours and afterwards the MgH 2 -TTNT composite was milled for 20 minutes. Transmission Electronic Microscopy (TEM) and Scanning Electron Microscopy (SEM) were used to evaluate the nanotube synthesis and show the particle morphology of the MgH 2 -TTNT composite, respectively. The Differential Scanning Calorimetry (DSC) examination provided some evidence with the shifting of the peaks obtained when the amount of TTNT is increased. The hydrogen absorption/desorption kinetics tests showed that the TTNT nanotubes can enhance hydrogen sorption effectively and the total hydrogen capacity obtained was 6.5 wt. (%). (author)

Activated aluminum hydride hydrogen storage compositions and uses thereof

Science.gov (United States)

Sandrock, Gary; Reilly, James; Graetz, Jason; Wegrzyn, James E.

2010-11-23

In one aspect, the invention relates to activated aluminum hydride hydrogen storage compositions containing aluminum hydride in the presence of, or absence of, hydrogen desorption stimulants. The invention particularly relates to such compositions having one or more hydrogen desorption stimulants selected from metal hydrides and metal aluminum hydrides. In another aspect, the invention relates to methods for generating hydrogen from such hydrogen storage compositions.

Hydrogen storage material and process using graphite additive with metal-doped complex hydrides

Science.gov (United States)

Zidan, Ragaiy [Aiken, SC; Ritter, James A [Lexington, SC; Ebner, Armin D [Lexington, SC; Wang, Jun [Columbia, SC; Holland, Charles E [Cayce, SC

2008-06-10

A hydrogen storage material having improved hydrogen absorbtion and desorption kinetics is provided by adding graphite to a complex hydride such as a metal-doped alanate, i.e., NaAlH.sub.4. The incorporation of graphite into the complex hydride significantly enhances the rate of hydrogen absorbtion and desorption and lowers the desorption temperature needed to release stored hydrogen.

Ice XVII as a Novel Material for Hydrogen Storage

Directory of Open Access Journals (Sweden)

Leonardo del Rosso

2017-02-01

Full Text Available Hydrogen storage is one of the most addressed issues in the green-economy field. The latest-discovered form of ice (XVII, obtained by application of an annealing treatment to a H 2 -filled ice sample in the C 0 -phase, could be inserted in the energy-storage context due to its surprising capacity of hydrogen physisorption, when exposed to even modest pressure (few mbars at temperature below 40 K, and desorption, when a thermal treatment is applied. In this work, we investigate quantitatively the adsorption properties of this simple material by means of spectroscopic and volumetric data, deriving its gravimetric and volumetric capacities as a function of the thermodynamic parameters, and calculating the usable capacity in isothermal conditions. The comparison of ice XVII with materials with a similar mechanism of hydrogen adsorption like metal-organic frameworks shows interesting performances of ice XVII in terms of hydrogen content, operating temperature and kinetics of adsorption-desorption. Any application of this material to realistic hydrogen tanks should take into account the thermodynamic limit of metastability of ice XVII, i.e., temperatures below about 130 K.

A systematic neutron reflectometry study on hydrogen absorption in thin Mg{sub 1-x}Al{sub x} alloy films

Energy Technology Data Exchange (ETDEWEB)

Fritzsche, H.; Poirier, E. [National Research Council of Canada, Chalk River, ON (Canada). Canadian Neutron Beam Centre; Haagsma, J.; Ophus, C.; Luber, E.; Harrower, C.T.; Mitlin, D. [Alberta Univ., Edmonton, AB (Canada). Dept. of Chemical and Materials Engineering; National Research Council of Canada, Edmonton, AB (Canada). National Inst. for Nanotechnology

2010-10-15

Various methods for storing hydrogen have been examined in an effort to find ways to store hydrogen in increasingly smaller volumes with decreasing weight of the whole hydrogen storage system. Metal hydrides, in which hydrogen is chemically bound to a metal atom, are considered to be very promising candidates for hydrogen storage because they have high gravimetric and volumetric storage capacities. This study investigated the effect of different magnesium (Mg) and aluminium (Al) ratios on the absorption and desorption properties of thin films. Neutron reflectometry (NR) was used in this study to better understand the absorption and desorption properties of commercially promising hydrogen storage materials. The large negative scattering length of hydrogen atoms changes the reflectivity curve substantially, so that NR can determine the total amount of stored hydrogen as well as the hydrogen distribution along the film normal, with nanometer resolution. In order to use NR, the samples must have smooth surfaces, and the film thickness should range between 10 and 200 nm. Thin Mg{sub 1-x}Al{sub x} alloy films (x = 0.2, 0.3, 0.4, 0.67) capped with a palladium (Pd) catalyst layer were used in this study. The NR experiments revealed that Mg{sub 0.7}Al{sub 0.3} is the optimum composition for this binary alloy system, with the highest amount of stored hydrogen and the lowest desorption temperature. All the thin films expanded by approximately 20 percent due to hydrogen absorption. The hydrogen was stored only in the MgAl layer without any hydrogen in the Pd layer. It was concluded that NR can be used to effectively determine the hydrogen profile in thin MgAl films. 29 refs., 5 figs.

Acidity, oxophilicity and hydrogen sticking probability of supported metal catalysts for hydrodeoxygenation process

Science.gov (United States)

Lup, A. Ng K.; Abnisa, F.; Daud, W. M. A. W.; Aroua, M. K.

2018-03-01

Hydrodeoxygenation is an oxygen removal process that occurs in the presence of hydrogen and catalysts. This study has shown the importance of acidity, oxophilicity and hydrogen sticking probability of supported metal catalysts in having high hydrodeoxygenation activity and selectivity. These properties are required to ensure the catalyst has high affinity for C-O or C=O bonds and the capability for the adsorption and activation of H2 and O-containing compounds. A theoretical framework of temperature programmed desorption technique was also discussed for the quantitative understanding of these properties. By using NH3-TPD, the nature and abundance of acid sites of catalyst can be determined. By using H2-TPD, the nature and abundance of metallic sites can also be determined. The desorption activation energy could also be determined based on the Redhead analysis of TPD spectra with different heating rates.

In situ measurements of fuel retention by laser induced desorption spectroscopy in TEXTOR

Science.gov (United States)

Zlobinski, M.; Philipps, V.; Schweer, B.; Huber, A.; Stoschus, H.; Brezinsek, S.; Samm, U.; TEXTOR Team

2011-12-01

In future fusion devices such as ITER tritium retention due to tritium co-deposition in mixed material layers can be a serious safety problem. Laser induced desorption spectroscopy (LIDS) can measure the hydrogen content of hydrogenic carbon layers locally on plasma-facing components, while hydrogen is used as a tritium substitute. For several years, this method has been applied in the TEXTOR tokamak in situ during plasma operation to monitor the hydrogen content in space and time. This work shows the LIDS signal reproducibility and studies the effects of different plasma conditions, desorption distances from the plasma and different laser energies using a dedicated sample with constant hydrogen amount. Also the LIDS signal evaluation procedure is described in detail and the detection limits for different conditions in the TEXTOR tokamak are estimated.

The effect of TTNT nanotubes on hydrogen sorption using MgH{sub 2}

Energy Technology Data Exchange (ETDEWEB)

Brum, Mariana Coutinho; Jardim, Paula Mendes; Conceicao, Monique Osorio Talarico da; Santos, Dilson Silva dos, E-mail: monique@metalmat.ufrj.br [Coordenacao dos Programas de Pos-Graduacao em Engenharia (PEMM/COPPEP/UFRJ), Rio de Janeiro, RJ (Brazil). Programa de Engenharia Metalurgica e de Materiais

2013-11-01

Nanotubes are promising materials to be used with magnesium hydride, as catalysts, in order to enhance hydrogen sorption. A study was performed on the hydrogen absorption/desorption properties of MgH{sub 2} with the addition of TTNT (TiTanate nanotubes). The MgH{sub 2} -TTNT composite was prepared by ball milling and the influence of the TTNT amount (1.0 and 5.0 wt. (%)) on the hydrogen capacity was evaluated. The milling of pure MgH{sub 2} was performed for 24 hours and afterwards the MgH{sub 2} -TTNT composite was milled for 20 minutes. Transmission Electronic Microscopy (TEM) and Scanning Electron Microscopy (SEM) were used to evaluate the nanotube synthesis and show the particle morphology of the MgH{sub 2} -TTNT composite, respectively. The Differential Scanning Calorimetry (DSC) examination provided some evidence with the shifting of the peaks obtained when the amount of TTNT is increased. The hydrogen absorption/desorption kinetics tests showed that the TTNT nanotubes can enhance hydrogen sorption effectively and the total hydrogen capacity obtained was 6.5 wt. (%). (author)

Hydrogen kinetics studies of MgH2-FeTi composites

Science.gov (United States)

Meena, Priyanka; Jangir, Mukesh; Singh, Ramvir; Sharma, V. K.; Jain, I. P.

2018-05-01

MgH2 + x wt% FeTi (x=10, 25, 50) nano composites were ball milled to get nano structured material and characterized for structural, morphological and thermal properties. XRD of the milled samples revealed the formation of MgH2, FeTi, Fe2Ti and H0.06FeTi phases. Morphological studies by SEM were undertaken to investigate the effect of hydrogenation of nanostructure alloy. EDX confirmed elemental composition of the as-prepared alloy. TGA studies showed higher desorption temperature for milled MgH2 compared to x wt% FeTi added MgH2. Activation energy for hydrogen desorption was found to be -177.90, -215.69, -162.46 and -87.93 kJ/mol for milled MgH2 and Mg2+x wt% FeTi (10, 25, 50), showing 89.97 kJ/ mol reduction in activation energy for 50 wt% alloy additives resulting in improved hydrogen storage capacity. DSC investigations were carried out to investigate the effect of alloy on hydrogen absorption behavior of MgH2.

Nanocrystalline NdFeB magnet prepared by mechanically activated disproportionation and desorption-recombination in-situ sintering

International Nuclear Information System (INIS)

Xiaoya, Liu; Yuping, Li; Lianxi, Hu

2013-01-01

The process of mechanically activated disproportionation and desorption-recombination in-situ sintering was proposed to synthesize highly densified nanocrystalline NdFeB magnet, and its validity was demonstrated by experimental investigation with the use of a Nd 16 Fe 76 B 8 (atomic ratio) alloy. Firstly, the as-cast alloy was disproportionated by mechanical milling in hydrogen, with the starting micron-sized Nd 2 Fe 14 B phase decomposed into an intimate mixture of nano-structured NdH 2.7 , Fe 2 B and α-Fe phases. The as-disproportionated alloy powders were compacted by cold pressing and then subjected to desorption-recombination in-situ sintering. The microstructure of both the as-disproportionated and the subsequently sintered samples was characterized by X-ray diffraction and electron transmission microscopy, respectively. The magnetic properties of the sintered samples were measured by using vibrating sample magnetometer. The results showed that, by vacuum sintering, not only was the powder compact consolidated, but also the as-disproportionated microstucture transformed into nanocrystalline Nd 2 Fe 14 B phase via the well-known desorption-recombination reaction, thus giving rise to nanocrystalline NdFeB magnet. In the present study, the optimal sintering parameters were found to be 780 °C×30 min. In this case, the coercivity, the remanence, and maximum energy product of the magnet sample achieved 0.8 T, 635.3 kA/m, and 106.3 kJ/m 3 , respectively. - Highlights: ► Nano-structured disproportionated NdFeB alloy powders by mechanical milling in hydrogen. ► Highly densified green magnet compact by cold pressing of as-disproportionated NdFeB alloy powders. ► Nanocrystalline NdFeB magnets by desorption-recombination in-situ sintering under vacuum. ► Magnetic properties significantly improved by relative density enhancement and nanocrystallization of Nd 2 Fe 14 B phase. ► The effects of sintering parameters on magnetic properties and the underlying

Hydrogen storage in Ti-Mn-(FeV) BCC alloys

International Nuclear Information System (INIS)

Santos, S.F.; Huot, J.

2009-01-01

Recently, the replacement of vanadium by the less expensive (FeV) commercial alloy has been investigated in Ti-Cr-V BCC solid solutions and promising results were reported. In the present work, this approach of using (FeV) alloys is adopted to synthesize alloys of the Ti-Mn-V system. Compared to the V-containing alloys, the alloys containing (FeV) have a smaller hydrogen storage capacity but a larger reversible hydrogen storage capacity, which is caused by the increase of the plateau pressure of desorption. Correlations between the structure and the hydrogen storage properties of the alloys are also discussed.

Chemical hydrogen storage material property guidelines for automotive applications

Science.gov (United States)

Semelsberger, Troy A.; Brooks, Kriston P.

2015-04-01

Chemical hydrogen storage is the sought after hydrogen storage media for automotive applications because of the expected low pressure operation (0.05 kg H2/kgsystem), and system volumetric capacities (>0.05 kg H2/Lsystem). Currently, the primary shortcomings of chemical hydrogen storage are regeneration efficiency, fuel cost and fuel phase (i.e., solid or slurry phase). Understanding the required material properties to meet the DOE Technical Targets for Onboard Hydrogen Storage Systems is a critical knowledge gap in the hydrogen storage research community. This study presents a set of fluid-phase chemical hydrogen storage material property guidelines for automotive applications meeting the 2017 DOE technical targets. Viable material properties were determined using a boiler-plate automotive system design. The fluid-phase chemical hydrogen storage media considered in this study were neat liquids, solutions, and non-settling homogeneous slurries. Material properties examined include kinetics, heats of reaction, fuel-cell impurities, gravimetric and volumetric hydrogen storage capacities, and regeneration efficiency. The material properties, although not exhaustive, are an essential first step in identifying viable chemical hydrogen storage material properties-and most important, their implications on system mass, system volume and system performance.

Effect of microwave irradiation on hydrogen sorption properties of hand mixed MgH{sub 2} – 10 wt.% carbon fibers

Energy Technology Data Exchange (ETDEWEB)

Awad, A.S. [Université de Bordeaux, ICMCB-CNRS, 87 Avenue du Dr Schweitzer, F-33600 Pessac (France); LCPM/PR2N, Université Libanaise, Faculté des Sciences 2, 90656 Jdeidet El Matn (Lebanon); Nakhl, M.; Zakhour, M. [LCPM/PR2N, Université Libanaise, Faculté des Sciences 2, 90656 Jdeidet El Matn (Lebanon); Santos, S.F.; Souza, F.L. [Universidade Federal do ABC, Avenida dos Estados 5001, 09210-580 Santo André – SP (Brazil); Bobet, J.-L., E-mail: jean-louis.bobet@u-bordeaux.fr [Université de Bordeaux, ICMCB-CNRS, 87 Avenue du Dr Schweitzer, F-33600 Pessac (France)

2016-08-15

The effect of microwave (MW) irradiation on the hydrogen sorption properties of magnesium powder is explored in the present work. MgH{sub 2} – 10 wt.% CFs (CFs = Carbons Fibers) was prepared by hand mixing, dehydrogenated under microwave irradiation for 20 s and then hydrogenated/dehydrogenated at about 300 °C – 1 MPa and 330 °C–0.03 MPa to investigate the effect of microwave irradiation on the solid/gas sorption properties. It has to be noted that the hydrogen absorption capacity and sorption kinetics of the MgH{sub 2} – 10 wt.% CFs mixture increased after dehydriding under MW irradiation. The MgH{sub 2} – 10 wt.% CFs mixture dehydrogenated by microwave irradiation can absorb about 5.8 wt.% and 5.3 wt.% H at 330 and 300 °C, respectively, within 2 h while the as-prepared MgH{sub 2} – 10 wt.% CFs mixture absorb only 4.6 wt.% H within the same duration. It is also demonstrated that MgH{sub 2} – 10 wt.% CFs mixture dehydrogenated by microwave irradiation exhibited good hydrogen desorption properties and, as an example, a microwave irradiated sample could release 5.8 wt.% H within 1 h at 330 °C in comparison to the as-prepared MgH{sub 2} – 10 wt.% CFs mixture which desorbed 4.4 wt.% H within 3 h. Scanning electron microscopy (SEM) images revealed that the particle sizes of the MW dehydrogenated mixture decreased after several solid/gas sorption cycles. This contribute to the improvement of hydrogen storage properties of the microwaves dehydrogenated MgH{sub 2} – 10 wt.% CFs mixture. In addition, the hydrogenated MgH{sub 2} – 10 wt.% CFs mixture show reproducible and better microwave-assisted dehydriding reaction during second microwaves cycle. - Highlights: • Dehydriding reaction of MgH{sub 2} by microwave method. • Effect of microwaves treatment on the hydrogen sorption properties of Mg. • Effect of discontinuous microwaves irradiation.

Hydrogen storage properties of LaMgNi3.6M0.4 (M = Ni, Co, Mn, Cu, Al) alloys

International Nuclear Information System (INIS)

Yang, Tai; Zhai, Tingting; Yuan, Zeming; Bu, Wengang; Xu, Sheng; Zhang, Yanghuan

2014-01-01

Highlights: • La–Mg–Ni system AB 2 -type alloys were prepared by induction melting. • Structures and lattice parameters were analysed by XRD. • Hydrogen absorption/desorption performances were studied. • Mechanisms of hydrogen absorption capacity fading were investigated. - Abstract: LaMgNi 3.6 M 0.4 (M = Ni, Co, Mn, Cu, Al) alloys were prepared through induction melting process. The phase compositions and crystal structures were characterised via X-ray diffraction (XRD). The hydrogen storage properties, including activation performance, hydrogen absorption capacity, cycle stability, alloy particle pulverisation and plateau pressure, were systemically investigated. Results show that Ni, Co, Mn and Cu substitution alloys exhibit multiphase structures comprising the main phase LaMgNi 4 and the secondary phase LaNi 5 . However, the secondary phase of the Al substitution alloy changes into LaAlNi 4 . The lattice parameters and cell volumes of the LaMgNi 4 phase follow the order Ni < Co < Al < Cu < Mn. Activation is simplified through partial substitution of Ni with Al, Cu and Co. The hydrogen absorption capacities of all of the alloys are approximately 1.7 wt.% at the first activation process; however, they rapidly decrease with increasing cycle number. In addition, the stabilities of hydriding and dehydriding cycles decrease in the order Al > Co > Ni > Cu > Mn. Hydriding processes result in numerous cracks and amorphisation of the LaMgNi 4 phase in the alloys. The p–c isotherms were determined by a Sieverts-type apparatus. Two plateaus were observed for the Ni, Co and Al substitution alloys, whereas only one plateau was found for Mn and Cu. This result was caused by the amorphisation of the LaMgNi 4 phase during the hydriding cycles. Reversible absorption and desorption of hydrogen are difficult to achieve. Substitutions of Ni with Co, Mn, Cu and Al significantly influence the reduction of hysteresis between hydriding and dehydriding

Solid solution barium–strontium chlorides with tunable ammonia desorption properties and superior storage capacity

Energy Technology Data Exchange (ETDEWEB)

Bialy, Agata [Amminex Emissions Technology A/S, Gladsaxevej 363, 2860 Soeborg (Denmark); Jensen, Peter B. [Department of Energy Conversion and Storage, Technical University of Denmark, Frederiksborgvej 399, DK-4000 Roskilde (Denmark); Center for Atomic-scale Materials Design, Department of Physics, Technical University of Denmark, Fysikvej 311, DK-2800 Kgs. Lyngby (Denmark); Blanchard, Didier [Department of Energy Conversion and Storage, Technical University of Denmark, Frederiksborgvej 399, DK-4000 Roskilde (Denmark); Vegge, Tejs, E-mail: teve@dtu.dk [Department of Energy Conversion and Storage, Technical University of Denmark, Frederiksborgvej 399, DK-4000 Roskilde (Denmark); Quaade, Ulrich J., E-mail: ujq@amminex.com [Amminex Emissions Technology A/S, Gladsaxevej 363, 2860 Soeborg (Denmark)

2015-01-15

Metal halide ammines are very attractive materials for ammonia absorption and storage—applications where the practically accessible or usable gravimetric and volumetric storage densities are of critical importance. Here we present, that by combining advanced computational materials prediction with spray drying and in situ thermogravimetric and structural characterization, we synthesize a range of new, stable barium-strontium chloride solid solutions with superior ammonia storage densities. By tuning the barium/strontium ratio, different crystallographic phases and compositions can be obtained with different ammonia ab- and desorption properties. In particular it is shown, that in the molar range of 35–50% barium and 65–50% strontium, stable materials can be produced with a practically usable ammonia density (both volumetric and gravimetric) that is higher than any of the pure metal halides, and with a practically accessible volumetric ammonia densities in excess of 99% of liquid ammonia. - Graphical abstract: Thermal desorption curves of ammonia from Ba{sub x}Sr{sub (1−x)}Cl{sub 2} mixtures with x equal to 0.125, 0.25 and 0.5 and atomic structure of Sr(NH{sub 3}){sub 8}Cl{sub 2}. - Highlights: • Solid solutions of strontium and barium chloride were synthesized by spray drying. • Adjusting molar ratios led to different crystallographic phases and compositions. • Different molar ratios led to different ammonia ab-/desorption properties. • 35–50 mol% BaCl{sub 2} in SrCl{sub 2} yields higher ammonia density than any other metal halide. • DFT calculations can be used to predict properties of the mixtures.

Desorption process of hydrogen starting from the Mg{sub 2}NiH{sub 4} and Mg{sub 2}NiH{sub 0.3}; Proceso de desorcion de hidrogeno a partir del hidruro intermetalico Mg{sub 2}NiH{sub 4} y Mg{sub 2}NiH{sub 0.3}

Energy Technology Data Exchange (ETDEWEB)

Iturbe G, J.L.; Basurto S, R.; Lopez M, B.E. [Departamento de Quimica, ININ, A.P. 18-1027, 11801 Mexico D.F. (Mexico)

2002-07-01

In this work the desorption velocity of H{sub 2} was determined starting from the magnesium nickel hydride once the reaction between the intermetallic and the hydrogen was realized, the compound were analysed by means of a thermogravimetric equipment, the conditions for carrying out the analysis were: 10 C by minute in nitrogen atmosphere at a volume of 50 ml by minute, subsequently the isotherms at different times were programmed and the desorption velocity of hydrogen was determined. The results show that the desorption velocity of hydrogen depends of the temperature, using only the nitrogen flux which acts as a carrier gas. Observing that the hydrogen liberation is carried out by means of two mechanisms according to the isotherms obtained. (Author)

Study on the complex Li-N-H hydrogen storage system

International Nuclear Information System (INIS)

Du, Linnan

2014-01-01

Nowadays the developments of clean energy technologies become more and more necessary and important. Hydrogen-powered vehicles are a promising alternative to the current fossil fuel based vehicle infrastructure. However, so far there is still no hydrogen storage material which can fit the standards for an on-board hydrogen storage system. On this background, this work deals with the development of a hydrogen storage material. The focus is put on the Lithium amide + Lithium hydride (LiNH 2 +LiH) hydrogen storage system because of its high theoretical capacity and relatively low desorption temperature. Moreover, Lithium amide + Magnesium hydride (LiNH 2 +MgH 2 ) as an alternative system was also briefly studied. The aims of this work are to achieve a deeper understanding of the reaction mechanism with the help of microstructural and thermodynamic studies, building a model to describe the sorption process and then to improve the system properties. As the desorption from LiNH 2 particles is the first step of the desorption process of the LiNH 2 +LiH system, the properties and sorption behavior of LiNH 2 sample materials were studied separately first. So the work in this thesis can be mainly divided into two parts: LiNH 2 samples and LiNH 2 +LiH samples. In order to activate the sample materials, both dry ball milling and wet ball milling (with tetrahydrofuran) methods were used. Boron nitride was mainly applied as catalyst. Furthermore, titanium tetrachloride was also used as an alternative additive. The sorption behaviors were studied with the help of a volumetric and a gravimetric system. Further investigation methods include X-ray Diffraction (XRD) method, Scanning Electron Microscope (SEM), Brunauer-Emmett-Teller (BET) method, Differential Thermal Analysis (DTA)/ Thermo Gravimetric Analysis (TGA)/ Mass Spectrometry (MS), and others. The results obtained in this work show that no obvious microstructure differences have been found between the wet ball milled and dry

Modification of the properties of Pt-Al/sub 2/O/sub 3/ catalysts by hydrogen at high temperatures

Energy Technology Data Exchange (ETDEWEB)

Menon, P.G.; Froment, G.F.

1979-08-01

Pulse reactor studies were performed on the hydrogenolysis of n-pentane and n-hexane at 400/sup 0/C on two commercial reforming catalysts that contained 0.6 and 0.75% platinum on alumina, respectively, and which were calcined in air at 500/sup 0/C, followed by hydrogen-reduction at 400/sup 0/-600/sup 0/C. On catalysts reduced at 400/sup 0/C, hydrogenolysis was the main reaction; with increasing reducing temperature, hydrogenolysis was suppressed and isomerization selectivity increased; at 550/sup 0/C pretreatment temperature, hydrogenolysis was near zero. This selective catalyst deactivation was reversed by oxidizing the catalyst in air at 500/sup 0/C in a similar manner as previously found for sulfided and chlorided catalysts. Temperature-programed desorption of hydrogen adsorbed at 20/sup 0/-600/sup 0/C revealed that the higher the adsorption temperature, the higher the temperature of the hydrogen desorption peaks: the hydrogen adsorbed below 400/sup 0/C desorbed mainly at 50/sup 0/-300/sup 0/C, but the hydrogen adsorbed at higher temperatures desorbed at 300/sup 0/-500/sup 0/C. Apparently, two types of hydrogen adsorb in the two temperature regions, of which the more strongly adsorbed type inhibits hydrogenolysis but not isomerization.

Deuterium desorption from tungsten using laser heating

Directory of Open Access Journals (Sweden)

J.H. Yu

2017-08-01

Full Text Available Retention and desorption of hydrogenic species need to be accurately modeled to predict the tritium inventory of next generation fusion devices, which is needed both for tritium fuel recovery and for tritium safety concerns. In this paper, experiments on thermal desorption of deuterium from intrinsic polycrystalline tungsten defects using laser heating are compared to TMAP-7 modeling. The samples during deuterium plasma exposure were at a temperature of 373K for this benchmark study with ion fluence of 0.7–1.0 ×1024Dm−2. Following plasma exposure, a fiber laser (λ= 1100nm heated the samples to peak surface temperatures ranging from ∼500 to 1400K with pulse widths from 10ms to 1s, and 1 to 10 pulses applied to each sample. The remaining deuterium retention was measured using temperature programmed desorption (TPD. Results show that > 95% of deuterium is desorbed when the peak surface temperature reached ∼950K for > 1s. TMAP-7 is used to predict deuterium desorption from tungsten for a range of surface temperatures and heating durations, and is compared to previous work on desorption from beryllium codeposits.

Preparation of Sm2Fe17-xGaxNy/Cy magnets by a hydrogenation-disproportionation-desorption-recombination process

International Nuclear Information System (INIS)

Kubis, M.; Cao, L.; Handstein, A.; Gebel, B.; Mueller, K.; Schultz, L.

1997-01-01

A hydrogenation-disproportionation-desorption-recombination process (HDDR) was applied to Sm 2 Fe 17-x Ga x (x=0.5, 1, and 2). The process was studied by means of temperature-pressure analysis, x-ray diffraction and scanning electron microscopy. It was shown that Ga not only stabilizes the interstitially modified compounds Sm 2 Fe 17-x Ga x C y (0 2 Fe 17-x Ga x against the disproportionation by hydrogen. Therefore, only for x=0.5 can a nearly complete HDDR be performed. The HDDR-treated and subsequently nitrogenated or carburized samples show coercivities μ 0J H C up to 3.1 T and 2.5 T, respectively. Hot compaction increases the density of the Sm 2 Fe 16.5 Ga 0.5 C y powder; however, it leads to a loss of coercivity due to decomposition into α-iron and samarium carbides. copyright 1997 American Institute of Physics

Ultrafine hydrogen storage powders

Science.gov (United States)

Anderson, Iver E.; Ellis, Timothy W.; Pecharsky, Vitalij K.; Ting, Jason; Terpstra, Robert; Bowman, Robert C.; Witham, Charles K.; Fultz, Brent T.; Bugga, Ratnakumar V.

2000-06-13

A method of making hydrogen storage powder resistant to fracture in service involves forming a melt having the appropriate composition for the hydrogen storage material, such, for example, LaNi.sub.5 and other AB.sub.5 type materials and AB.sub.5+x materials, where x is from about -2.5 to about +2.5, including x=0, and the melt is gas atomized under conditions of melt temperature and atomizing gas pressure to form generally spherical powder particles. The hydrogen storage powder exhibits improved chemcial homogeneity as a result of rapid solidfication from the melt and small particle size that is more resistant to microcracking during hydrogen absorption/desorption cycling. A hydrogen storage component, such as an electrode for a battery or electrochemical fuel cell, made from the gas atomized hydrogen storage material is resistant to hydrogen degradation upon hydrogen absorption/desorption that occurs for example, during charging/discharging of a battery. Such hydrogen storage components can be made by consolidating and optionally sintering the gas atomized hydrogen storage powder or alternately by shaping the gas atomized powder and a suitable binder to a desired configuration in a mold or die.

Hydrogen behaviour study in plasma facing a-C:H and a-SiC:H hydrogenated amorphous materials for fusion reactors

International Nuclear Information System (INIS)

Barbier, Gauzelin

1997-01-01

Plasma facing components of controlled fusion test devices (tokamaks) are submitted to several constraints (irradiation, high temperatures). The erosion (physical sputtering and chemical erosion) and the hydrogen recycling (retention and desorption) of these materials influence many plasma parameters and thus affect drastically the tokamak running. Firstly, we will describe the different plasma-material interactions. It will be pointed out, how erosion and hydrogen recycling are strongly related to both chemical and physical properties of the material. In order to reduce this interactions, we have selected two amorphous hydrogenated materials (a-C:H and a-SiC:H), which are known for their good thermal and chemical qualities. Some samples have been then implanted with lithium ions at different fluences. Our materials have been then irradiated with deuterium ions at low energy. From our results, it is shown that both the lithium implantation and the use of an a-SiC:H substrate can be benefit in enhancing the hydrogen retention. These results were completed with thermal desorption studies of these materials. It was evidenced that the hydrogen fixation was more efficient in a -SiC:H than in a-C:H substrate. Results in good agreement with those described above have been obtained by exposing a-C:H and a-SiC:H samples to the scrape off layer of the tokamak of Varennes (TdeV, Canada). A modeling of hydrogen diffusion under irradiation has been also proposed. (author)

Storage and characterization of the hydrogen in mixed oxides on base of cerium-nickel and zirconium or the aluminium

International Nuclear Information System (INIS)

Debeusscher, S.

2008-12-01

The mixed oxides based on cerium-nickel and zirconium or aluminium are able to store large quantities of hydrogen, To determine nature, reactivity and properties of hydrogen species (spill-over, direct desorption), the solid were studied by different physicochemical techniques in the dried, calcined and partially reduced states: XRD, porosity, TGA, TPR, TPA, TPD, chemical titration and inelastic neutron scattering (INS). Solids are mainly meso-porous with a common pore size at 4 nm, They are constituted of CeO 2 phase, Ce-Ni or Ce-Ni-Zr solid solution and of Ni(OH) 2 in the dried state and NiO in the calcined state. The Ni species are in various environments and the strong interactions between the cations in solid solution and at different particles interface influence their reducibility and the creation of anionic vacancies. Activation in H 2 in temperature is determining for hydrogen storage in the solid while calcination step is not necessary. INS Analyses evidence that the hydrogen species inserted during treatment in H 2 are H + (OH - ), hydride H - and H * (metallic nickel) species, present in various chemical environments, in particular for hydride species. All kinds of hydrogen species participate to the reaction during the chemical titration in agreement with the proposed hydrogenation mechanism. The study of the adsorption of hydrogen shows that this step is fast and in quantity of the same order as that measured by chemical titration. The direct desorption of H 2 is very low, linked to the presence of hydrogen in interaction with metallic nickel (H *- .). Desorption of water is also observed, in parallel, corresponding to the elimination of groups. The hydride species are not desorbed. These various observations allow connecting hydrogen species properties with their localization in the structure and to model active sites. (author)

Hydrogen absorption-desorption at metal surfaces

International Nuclear Information System (INIS)

Ward, C.A.; Pataki, L.

1991-04-01

On the basis of experimental studies, it has been proposed that when zirconium oxide (ZrO 2 ) is exposed to hydrogen at 300 degrees C or higher, a reaction occurs to produce metallic zirconium and water, thereby increasing the electrical conductivity of the oxide film and its permeability to hydrogen. A series of experiments has been performed in which specimens of zirconium and zirconium-2.5% niobium were either hydrided or deuterided in a furnace at a temperature between 300 degrees C and 800 degrees C and in an atmosphere that consisted primarily of either hydrogen (H 2 ) or deuterium (D 2 ). After cooling a specimen to room temperature, it was placed in a thermogravimetric analyzer that was equipped with a mass spectrometer, TGA-MS. Each specimen was then heated to 1200 degrees C at a controlled rate in a primarily helium atmosphere monitored with the mass spectrometer. Light water (H 2 O) evolved from the hydrided specimens and heavy water (D 2 0) from the deuterided ones and there was a weight loss of the specimens that accompanied the water evolution. The specimens having approximately the same amount of hydride but more oxide also evolved more H 2 O, and that the H 2 O did not come from reactions between impurity H 2 and oxygen (O 2 ) in the TGA-MS. Heating a zirconium or zirconium alloy specimen that contains a hydride or deuteride phase within and an oxide layer on its surface causes the hydrogen to diffuse toward the surface and when it encounters the oxide a reaction follows that produces water. The conventional mechanism for the dissipation of the imperviousness of ZrO 2 to H 2 that results from the oxide being exposed to a reducing atmosphere will not explain the water production observed in these experiments. However, the existence of the proposed reaction can account for the elevated hydrogen concentration in an oxide film that has been observed to accompany the aqueous corrosion of zirconium and the effects on both the electrical conductivity and

Mecanical Properties Degradation by Hydrogen Embrittlement

International Nuclear Information System (INIS)

Bertolino, G; Meyer, G; Perez Ipina J

2001-01-01

The presence of hydrogen-rich media during nuclear plant operation motivates the study of the zirconium alloys degradation of their mechanical properties influenced by hydrogen content and temperature.In this work we study samples with a microstructure of equiaxial grains resulted from hot-rolled, and with different homogeneous hydrogen content obtained by electrochemical charge and a thermal treatment.The influence of hydrogen content and temperature was analyzed from the results of fracture-mechanical tests on CT (compact test) probes using the J-criteria

Hydrogenation properties of Zr films under various conditions of hydrogen plasma

CERN Document Server

Yan Guo Qiang; Zhou Zhu Ying; Zhao Guo Qing; Hu Pei Gang; Luo Shun Zhong; Peng Shu Ming; Ding Wei; Long Xing Gui

2002-01-01

The hydrogenation properties of Zr samples with and without an Ni overlayer under various plasma conditions were investigated by means of non-Rutherford backscattering and elastic recoil detection analysis. The theoretical maximum hydrogen capacity, 66.7 at%, could be achieved at a hydrogen absolute pressure of approx 2 Pa and a substrate temperature of approx 393K for a plasma irradiation of only 10 min; this was significantly greater than that for gas hydrogenation under the same hydrogen pressure and substrate temperature. It was also found that the C and O contamination on the sample surface strongly influences the hydrogenation, and that the maximum equilibrium hydrogen content drops dramatically with the increasing total contamination. In addition, the influence of the Ni overlayer on the plasma hydrogenation is discussed

A systematic neutron reflectometry study on hydrogen absorption in thin Mg{sub 1-x}Al{sub x} alloy films

Energy Technology Data Exchange (ETDEWEB)

Fritzsche, H.; Poirier, E., E-mail: helmut.fritzsche@nrc.gc.ca [National Research Council Canada, Canadian Neutron Beam Centre, Chalk River, ON (Canada); Haagsma, J.; Ophus, C.; Luber, E.; Harrower, C.; Mitlin, D. [Univ. of Alberta, and National Research Council Canada, Chemical and Materials Engineering, Edmonton, AB (Canada)

2010-10-15

In this article, we show how neutron reflectometry (NR) can provide deep insight into the absorption and desorption properties of commercially promising hydrogen storage materials. NR benefits from the large negative scattering length of hydrogen atoms, which changes the reflectivity curve substantially, so that NR can determine not only the total amount of stored hydrogen but also the hydrogen distribution along the film normal, with nanometer resolution. To use NR, the samples must have smooth surfaces, and the film thickness should range between 10 and 200 nm. We performed a systematic study on thin Mg{sub 1-x}Al{sub x} alloy films (x = 0.2, 0.3, 0.4, 0.67) capped with a Pd catalyst layer. Our NR experiments showed that Mg{sub 0.7}Al{sub 0.3} is the optimum alloy composition with the highest amount of stored hydrogen and the lowest desorption temperature. All the thin films expand by about 20% because of hydrogen absorption, and the hydrogen is stored only in the MgAl layer with no hydrogen content in the Pd layer. (author)

Positron annihilation study of hydrogen storage alloys

International Nuclear Information System (INIS)

Shirai, Yasuharu; Araki, Hideki; Sakaki, Kouji

2003-01-01

Some AB 5 and AB 2 hydrogen storage alloys have been characterized by using positron-annihilation lifetime spectroscopy. It has been shown that they contain no constitutional vacancies and that deviations from the stoichiometric compositions are all compensated by antistructure atoms. Positron lifetimes in fully-annealed LaNi 5-x Al x and MmNi 5-x Al x alloys show good correlation with their hydrogen desorption pressures. On the other hand, surprising amounts of vacancies together with dislocations have been found to be generated during the first hydrogen absorption process of LaNi 5 and ZrMn 2 . These lattice defects play important role in hydrogen absorption-desorption processes of hydrogen storage alloys. (author)

Nanocrystalline NdFeB magnet prepared by mechanically activated disproportionation and desorption-recombination in-situ sintering

Energy Technology Data Exchange (ETDEWEB)

Xiaoya, Liu; Yuping, Li [School of Materials Science and Engineering, Harbin Institute of Technology, Harbin 150001 (China); Lianxi, Hu, E-mail: hulx@hit.edu.cn [School of Materials Science and Engineering, Harbin Institute of Technology, Harbin 150001 (China)

2013-03-15

The process of mechanically activated disproportionation and desorption-recombination in-situ sintering was proposed to synthesize highly densified nanocrystalline NdFeB magnet, and its validity was demonstrated by experimental investigation with the use of a Nd{sub 16}Fe{sub 76}B{sub 8} (atomic ratio) alloy. Firstly, the as-cast alloy was disproportionated by mechanical milling in hydrogen, with the starting micron-sized Nd{sub 2}Fe{sub 14}B phase decomposed into an intimate mixture of nano-structured NdH{sub 2.7}, Fe{sub 2}B and {alpha}-Fe phases. The as-disproportionated alloy powders were compacted by cold pressing and then subjected to desorption-recombination in-situ sintering. The microstructure of both the as-disproportionated and the subsequently sintered samples was characterized by X-ray diffraction and electron transmission microscopy, respectively. The magnetic properties of the sintered samples were measured by using vibrating sample magnetometer. The results showed that, by vacuum sintering, not only was the powder compact consolidated, but also the as-disproportionated microstucture transformed into nanocrystalline Nd{sub 2}Fe{sub 14}B phase via the well-known desorption-recombination reaction, thus giving rise to nanocrystalline NdFeB magnet. In the present study, the optimal sintering parameters were found to be 780 Degree-Sign C Multiplication-Sign 30 min. In this case, the coercivity, the remanence, and maximum energy product of the magnet sample achieved 0.8 T, 635.3 kA/m, and 106.3 kJ/m{sup 3}, respectively. - Highlights: Black-Right-Pointing-Pointer Nano-structured disproportionated NdFeB alloy powders by mechanical milling in hydrogen. Black-Right-Pointing-Pointer Highly densified green magnet compact by cold pressing of as-disproportionated NdFeB alloy powders. Black-Right-Pointing-Pointer Nanocrystalline NdFeB magnets by desorption-recombination in-situ sintering under vacuum. Black-Right-Pointing-Pointer Magnetic properties significantly

Hydrogen storage properties of LaMgNi{sub 3.6}M{sub 0.4} (M = Ni, Co, Mn, Cu, Al) alloys

Energy Technology Data Exchange (ETDEWEB)

Yang, Tai [Department of Functional Material Research, Central Iron and Steel Research Institute, Beijing 100081 (China); Key Laboratory of Integrated Exploitation of Baiyun Obo Multi-Metal Resources, Inner Mongolia University of Science and Technology, Baotou 014010 (China); Zhai, Tingting; Yuan, Zeming; Bu, Wengang [Department of Functional Material Research, Central Iron and Steel Research Institute, Beijing 100081 (China); Xu, Sheng [Key Laboratory of Integrated Exploitation of Baiyun Obo Multi-Metal Resources, Inner Mongolia University of Science and Technology, Baotou 014010 (China); Zhang, Yanghuan, E-mail: zhangyh59@sina.com [Department of Functional Material Research, Central Iron and Steel Research Institute, Beijing 100081 (China); Key Laboratory of Integrated Exploitation of Baiyun Obo Multi-Metal Resources, Inner Mongolia University of Science and Technology, Baotou 014010 (China)

2014-12-25

Highlights: • La–Mg–Ni system AB{sub 2}-type alloys were prepared by induction melting. • Structures and lattice parameters were analysed by XRD. • Hydrogen absorption/desorption performances were studied. • Mechanisms of hydrogen absorption capacity fading were investigated. - Abstract: LaMgNi{sub 3.6}M{sub 0.4} (M = Ni, Co, Mn, Cu, Al) alloys were prepared through induction melting process. The phase compositions and crystal structures were characterised via X-ray diffraction (XRD). The hydrogen storage properties, including activation performance, hydrogen absorption capacity, cycle stability, alloy particle pulverisation and plateau pressure, were systemically investigated. Results show that Ni, Co, Mn and Cu substitution alloys exhibit multiphase structures comprising the main phase LaMgNi{sub 4} and the secondary phase LaNi{sub 5}. However, the secondary phase of the Al substitution alloy changes into LaAlNi{sub 4}. The lattice parameters and cell volumes of the LaMgNi{sub 4} phase follow the order Ni < Co < Al < Cu < Mn. Activation is simplified through partial substitution of Ni with Al, Cu and Co. The hydrogen absorption capacities of all of the alloys are approximately 1.7 wt.% at the first activation process; however, they rapidly decrease with increasing cycle number. In addition, the stabilities of hydriding and dehydriding cycles decrease in the order Al > Co > Ni > Cu > Mn. Hydriding processes result in numerous cracks and amorphisation of the LaMgNi{sub 4} phase in the alloys. The p–c isotherms were determined by a Sieverts-type apparatus. Two plateaus were observed for the Ni, Co and Al substitution alloys, whereas only one plateau was found for Mn and Cu. This result was caused by the amorphisation of the LaMgNi{sub 4} phase during the hydriding cycles. Reversible absorption and desorption of hydrogen are difficult to achieve. Substitutions of Ni with Co, Mn, Cu and Al significantly influence the reduction of hysteresis between

Hydrogenation-disproportionation-desorption-recombination in Sm{sub 2}Fe{sub 16}M (M=Al, Ga and Si) and magnetic properties of their carburized powders

Energy Technology Data Exchange (ETDEWEB)

Kubis, M.; Rave, W.; Cao, L.; Gebel, B.; Mueller, K.-H.; Schultz, L. [Institut fuer Festkoerper- und Werkstofforschung Dresden e.V. (Germany)

1998-11-20

The application of the hydrogenation-disproportionation-desorption-recombination (HDDR) process in Sm{sub 2}Fe{sub 16}M (M=Al,Ga and Si) was investigated. The hydrogen absorption behaviour was studied by temperature-pressure analysis (TPA). In the temperature range between 500 and 800 C, Sm{sub 2}Fe{sub 16}M samples with M=Ga and Si show a weaker hydrogen absorption than Sm{sub 2}Fe{sub 16}Al. This was confirmed by X-ray diffraction which showed a complete disproportionation of Sm{sub 2}Fe{sub 16}Al into SmH{sub z} (1.9hydrogen for M=Ga and Si. The magnetization processes of carburized HDDR powders were studied by VSM measurements and Kerr microscopy. The demagnetization curve of our HDDR processed Sm{sub 2}Fe{sub 16}AlC{sub y} is well shaped, whereas those of Sm{sub 2}Fe{sub 16}GaC{sub y} and Sm{sub 2}Fe{sub 16}SiC{sub y} show a large decrease of the polarization at low fields. The favourable behaviour of Sm{sub 2}Fe{sub 16}AlC{sub y} is due to a homogeneous submicron grain structure. In Sm{sub 2}Fe{sub 16}GaC{sub y} and Sm{sub 2}Fe{sub 16}SiC{sub y} samples, an additional, magnetically soft phase with larger domains was observed which causes the low coercivity. As a consequence, HDDR was only favourable for the preparation of Sm{sub 2}Fe{sub 16}MC{sub y} hard magnets with M=Al but not for M=Ga and Si. Optimization of the HDDR process in Sm{sub 2}Fe{sub 16}Al and subsequent nitrogenation or carburization led to coercivities of {mu}{sub 0j}H{sub c}=2.9 and 2.5 T, respectively. (orig.) 11 refs.

Processing routes evaluation of severely deformed Mg-Fe alloys for hydrogen storage applications

International Nuclear Information System (INIS)

Antiqueira, F.J.; Leiva, D.R.; Ishikawa, T.T.; Jorge Junior, A.M.; Botta, W.J.

2016-01-01

MgH 2 is considered an interesting material for safe hydrogen storage in the solid state, due to its high gravimetric nominal capacity of 7,6%, and the relative low cost of magnesium. In this study, we attempted to improve the performance of the MgH 2 in the hydrogen storage. Different processing routes for Mg and Mg-Fe by severe plastic deformation were evaluated. The prepared materials were characterized by X-ray diffraction (XRD), scanning (SEM) and transmission electron microscopy (TEM). The hydrogen storage properties were evaluated by differential scanning calorimetry and the Sievert's method. The results indicate superior properties to materials catalyzed with iron, as well as a high dependence of hydrogen absorption / desorption kinetic in accordance with the microstructures obtained through the various processing routes. (author)

Study on the complex Li-N-H hydrogen storage system

Energy Technology Data Exchange (ETDEWEB)

Du, Linnan

2014-07-01

Nowadays the developments of clean energy technologies become more and more necessary and important. Hydrogen-powered vehicles are a promising alternative to the current fossil fuel based vehicle infrastructure. However, so far there is still no hydrogen storage material which can fit the standards for an on-board hydrogen storage system. On this background, this work deals with the development of a hydrogen storage material. The focus is put on the Lithium amide + Lithium hydride (LiNH{sub 2}+LiH) hydrogen storage system because of its high theoretical capacity and relatively low desorption temperature. Moreover, Lithium amide + Magnesium hydride (LiNH{sub 2}+MgH{sub 2}) as an alternative system was also briefly studied. The aims of this work are to achieve a deeper understanding of the reaction mechanism with the help of microstructural and thermodynamic studies, building a model to describe the sorption process and then to improve the system properties. As the desorption from LiNH{sub 2} particles is the first step of the desorption process of the LiNH{sub 2}+LiH system, the properties and sorption behavior of LiNH{sub 2} sample materials were studied separately first. So the work in this thesis can be mainly divided into two parts: LiNH{sub 2} samples and LiNH{sub 2}+LiH samples. In order to activate the sample materials, both dry ball milling and wet ball milling (with tetrahydrofuran) methods were used. Boron nitride was mainly applied as catalyst. Furthermore, titanium tetrachloride was also used as an alternative additive. The sorption behaviors were studied with the help of a volumetric and a gravimetric system. Further investigation methods include X-ray Diffraction (XRD) method, Scanning Electron Microscope (SEM), Brunauer-Emmett-Teller (BET) method, Differential Thermal Analysis (DTA)/ Thermo Gravimetric Analysis (TGA)/ Mass Spectrometry (MS), and others. The results obtained in this work show that no obvious microstructure differences have been found

Gas desorption during friction of amorphous carbon films

International Nuclear Information System (INIS)

Rusanov, A; Fontaine, J; Martin, J-M; Mogne, T L; Nevshupa, R

2008-01-01

Gas desorption induced by friction of solids, i.e. tribodesorption, is one of the numerous physical and chemical phenomena, which arise during friction as result of thermal and structural activation of material in a friction zone. Tribodesorption of carbon oxides, hydrocarbons, and water vapours may lead to significant deterioration of ultra high vacuum conditions in modern technological equipment in electronic, optoelectronic industries. Therefore, knowledge of tribodesorption is crucial for the performance and lifetime of vacuum tribosystems. Diamond-like carbon (DLC) coatings are interesting materials for vacuum tribological systems due to their high wear resistance and low friction. Highly hydrogenated amorphous carbon (a-C:H) films are known to exhibit extremely low friction coefficient under high vacuum or inert environment, known as 'superlubricity' or 'superlow friction'. However, the superlow friction period is not always stable and then tends to spontaneous transition to high friction. It is supposed that hydrogen supply from the bulk to the surface is crucial for establishing and maintaining superlow friction. Thus, tribodesorption can serve also as a new technique to determine the role of gases in superlow friction mechanisms. Desorption of various a-C:H films, deposited by PECVD, ion-beam deposition and deposition using diode system, has been studied by means of ultra-high vacuum tribometer equipped with a mass spectrometer. It was found that in superlow friction period desorption rate was below the detection limit in the 0-85 mass range. However, transition from superlow friction to high friction was accompanied by desorption of various gases, mainly of H 2 and CH 4 . During friction transition, surfaces were heavily damaged. In experiments with DLC films with low hydrogen content tribodesorption was significant during the whole experiment, while low friction was not observed. From estimation of maximum surface temperature during sliding contact it

Thermodynamic and structural properties of ball-milled mixtures composed of nano-structural graphite and alkali(-earth) metal hydride

International Nuclear Information System (INIS)

Miyaoka, Hiroki; Ichikawa, Takayuki; Fujii, Hironobu

2007-01-01

Hydrogen desorption properties of mechanically milled materials composed of nano-structural hydrogenated-graphite (C nano H x ) and alkali(-earth) metal hydride (MH; M = Na, Mg and Ca) were investigated from the thermodynamic and structural points of view. The hydrogen desorption temperature for all the C nano H x and MH composites was obviously lower than that of the corresponding each hydride. In addition, the desorption of hydrocarbons from C nano H x was significantly suppressed by making composite of C nano H x with MH, even though C nano H x itself thermally desorbs a considerably large amount of hydrocarbons. These results indicate that an interaction exists between C nano H x and MH, and hydrogen in both the phases is destabilized by a close contact between polar C-H groups in C nano H x and the MH solid phase. Moreover, a new type of chemical bonding between the nano-structural carbon (C nano ) and the Li, Ca, or Mg metal atoms may be formed after hydrogen desorption. Thus, the above metal-C-H system would be recognized as a new family of H-storage materials

Study of the hydrogen behavior in amorphous hydrogenated materials of type a - C:H and a - SiC:H facing fusion reactor plasma

International Nuclear Information System (INIS)

Barbier, G.

1997-01-01

Plasma facing components of controlled fusion test devices (tokamaks) are submitted to several constraints (irradiation, high temperatures). The erosion (physical sputtering and chemical erosion) and the hydrogen recycling (retention and desorption) of these materials influence many plasma parameters and thus affect drastically the tokamak running. First, we will describe the different plasma-material interactions. It will be pointed out, how erosion and hydrogen recycling are strongly related to both chemical and physical properties of the material. In order to reduce these interactions, we have selected two amorphous hydrogenated materials (a-C:H and a-SiC:H), which are known for their good thermal and chemical qualities. Some samples have been then implanted with lithium ions at different fluences. Our materials have been then irradiated with deuterium ions at low energy. From our results, it is shown that both the lithium implantation and the use of an a - SiC:H substrate can be beneficial in enhancing the hydrogen retention. These results were completed with thermal desorption studies of these materials. It was evidenced that the hydrogen fixation was more efficient in a-SiC:H than in a-C:H substrate. Results in good agreement with those described above have been obtained by exposing a - C:H and a - SiC:H samples to the scrape off layer of the tokamak of Varennes (TdeV, Canada). A modelling of hydrogen diffusion under irradiation has been also proposed. (author)

Electron beam exposure mechanisms in hydrogen silsesquioxane investigated by vibrational spectroscopy and in-situ electron beam induced desorption

Energy Technology Data Exchange (ETDEWEB)

Olynick, D.L.; Cord, B.; Schipotinin, A.; Ogletree, D.F.; Schuck, P.J.

2009-11-13

Hydrogen Silsesquioxane (HSQ) is used as a high-resolution resist with resolution down below 10nm half-pitch. This material or materials with related functionalities could have widespread impact in nanolithography and nanoscience applications if the exposure mechanism was understood and instabilities controlled. Here we have directly investigated the exposure mechanism using vibrational spectroscopy (both Raman and Fourier transform Infrared) and electron beam desorption spectrocscopy (EBDS). In the non-networked HSQ system, silicon atoms sit at the corners of a cubic structure. Each silicon is bonded to a hydrogen atom and bridges 3 oxygen atoms (formula: HSiO3/2). For the first time, we have shown, via changes in the Si-H2 peak at ~;;2200 cm -1 in the Raman spectra and the release of SiHx products in EBID, that electron-bam exposed materials crosslinks via a redistribution reaction. In addition, we observe the release of significantly more H2 than SiH2 during EBID, which is indicative of additional reaction mechanisms. Additionally, we compare the behavior of HSQ in response to both thermal and electron-beam induced reactions.

Interaction of hydrogen with palladium clusters deposited on graphene

Energy Technology Data Exchange (ETDEWEB)

Alonso, Julio A.; Granja, Alejandra; Cabria, Iván; López, María J. [Departamento de Física Teórica, Atómica y Optica, Universidad de Valladolid, 47011 Valladolid (Spain)

2015-12-31

Hydrogen adsorption on nanoporous carbon materials is a promising technology for hydrogen storage. However, pure carbon materials do not meet the technological requirements due to the week binding of hydrogen to the pore walls. Experimental work has shown that doping with Pd atoms and clusters enhances the storage capacity of porous carbons. Therefore, we have investigated the role played by the Pd dopant on the enhancement mechanisms. By performing density functional calculations, we have found that hydrogen adsorbs on Pd clusters deposited on graphene following two channels, molecular adsorption and dissociative chemisorption. However, desorption of Pd-H complexes competes with desorption of hydrogen, and consequently desorption of Pd-H complexes would spoil the beneficial effect of the dopant. As a way to overcome this difficulty, Pd atoms and clusters can be anchored to defects of the graphene layer, like graphene vacancies. The competition between molecular adsorption and dissociative chemisorption of H{sub 2} on Pd{sub 6} anchored on a graphene vacancy has been studied in detail.

Interaction of hydrogen with palladium clusters deposited on graphene

Science.gov (United States)

Alonso, Julio A.; Granja, Alejandra; Cabria, Iván; López, María J.

2015-12-01

Hydrogen adsorption on nanoporous carbon materials is a promising technology for hydrogen storage. However, pure carbon materials do not meet the technological requirements due to the week binding of hydrogen to the pore walls. Experimental work has shown that doping with Pd atoms and clusters enhances the storage capacity of porous carbons. Therefore, we have investigated the role played by the Pd dopant on the enhancement mechanisms. By performing density functional calculations, we have found that hydrogen adsorbs on Pd clusters deposited on graphene following two channels, molecular adsorption and dissociative chemisorption. However, desorption of Pd-H complexes competes with desorption of hydrogen, and consequently desorption of Pd-H complexes would spoil the beneficial effect of the dopant. As a way to overcome this difficulty, Pd atoms and clusters can be anchored to defects of the graphene layer, like graphene vacancies. The competition between molecular adsorption and dissociative chemisorption of H2 on Pd6 anchored on a graphene vacancy has been studied in detail.

Study of the hydrogen behavior in amorphous hydrogenated materials of type a - C:H and a - SiC:H facing fusion reactor plasma; Etude du comportament de l`hydrogene dans des materiaux amorphes hydrogenes de type a - C:H et a - SiC:H devant faire face au plasma des reacteurs a fusion

Energy Technology Data Exchange (ETDEWEB)

Barbier, G. [Lyon-1 Univ., 69 - Villeurbanne (France). Inst. de Physique Nucleaire

1997-04-10

Plasma facing components of controlled fusion test devices (tokamaks) are submitted to several constraints (irradiation, high temperatures). The erosion (physical sputtering and chemical erosion) and the hydrogen recycling (retention and desorption) of these materials influence many plasma parameters and thus affect drastically the tokamak running. First, we will describe the different plasma-material interactions. It will be pointed out, how erosion and hydrogen recycling are strongly related to both chemical and physical properties of the material. In order to reduce these interactions, we have selected two amorphous hydrogenated materials (a-C:H and a-SiC:H), which are known for their good thermal and chemical qualities. Some samples have been then implanted with lithium ions at different fluences. Our materials have been then irradiated with deuterium ions at low energy. From our results, it is shown that both the lithium implantation and the use of an a - SiC:H substrate can be beneficial in enhancing the hydrogen retention. These results were completed with thermal desorption studies of these materials. It was evidenced that the hydrogen fixation was more efficient in a-SiC:H than in a-C:H substrate. Results in good agreement with those described above have been obtained by exposing a - C:H and a - SiC:H samples to the scrape off layer of the tokamak of Varennes (TdeV, Canada). A modelling of hydrogen diffusion under irradiation has been also proposed. (author) 176 refs.

Report on the results of the FY 1998 hydrogen utilization international clean energy system technology (WE-NET). Subtask 5. Survey on the R and D of technologies for hydrogen transport and storage by hydrogen absorbing alloys (V. Development of the distributed transport/storage use hydrogen absorbing alloys); 1998 nendo suiso riyo kokusai clean energy system gijutsu (WE-NET). 5. Suiso yuso chozo gijutsu no kaihatsu (V. bunsan yuso chozoyo suiso kyuzo gokin no kaihatsu)

Energy Technology Data Exchange (ETDEWEB)

NONE

1999-03-01

The paper described the FY 1998 results of the development of hydrogen distributed transport/storage use absorbing alloys in the WE-NET project. Study was made of improvement of hydrogen desorption characteristics by substituting Ca for part of Mg of Mg-Ni alloys and substituting Cr for part of Ni. It is necessary to shift the state of atomic bond by H atom and metal atom in alloys from the ionic bond to the metallic bond, and to change from the amorphous state to the BCC type crystal structure. It was found out that it was possible to do it by improving the composition and heat treatment. The addition of Cu to LaMg{sub 2} alloys shifts the bond with hydrogen to the bond with metal. Easy hydrogen desorption and large absorbing capacity can be expected. It was found out that LaMg{sub 2}Cu{sub 2} synthesized by the reaction sintering method has reversible hydrogen absorbing desorption characteristics. The absorbing amount is 2.4 wt%, the desorption amount 1.2 wt%, and the desorption temperature 190 degrees C. Those are still far from WE-NET targeted values, but a clue to the search was obtained. It was found out that by applying doping technology by Ti, etc. to NaAlH{sub 4}, characteristics can be expected of the desorption amount, 4.5 wt%, of the hydrogen desorption starting temperature from 100 degrees C to 200 degrees C. (NEDO)

Desorption of H atoms from graphite (0001) using XUV free electron laser pulses

DEFF Research Database (Denmark)

Siemer, B.; Olsen, Thomas; Hoger, T.

2010-01-01

The desorption of neutral H atoms from graphite with femtosecond XUV pulses is reported. The velocity distribution of the atoms peaks at extremely low kinetic energies. A DFT-based electron scattering calculation traces this distribution to desorption out of specific adsorption sites on graphite......, and identifies the highest vibrational state in the adsorbate potential as a major source for the slow atoms. It is evident that multiple electron scattering processes are required for this desorption. A direct electronic excitation of a repulsive hydrogen-carbon bond seems not to be important....

Surface Structures and Thermal Desorption Behaviors of Cyclopentanethiol Self-Assembled Monolayers on Au(111)

International Nuclear Information System (INIS)

Kang, Hun Gu; Kim, You Young; Park, Tae Sun; Noh, Jae Geun; Park, Joon B.; Ito, Eisuke; Hara, Masahiko

2011-01-01

The surface structures, adsorption conditions, and thermal desorption behaviors of cyclopentanethiol (CPT) self-assembled monolayers (SAMs) on Au(111) were investigated by scanning tunneling microscopy (STM), X-ray photoelectron spectroscopy (XPS), and thermal desorption spectroscopy (TDS). STM imaging revealed that although the adsorption of CPT on Au(111) at room temperature generates disordered SAMs, CPT molecules at 50 .deg. C formed well-ordered SAMs with a (2√3 x √5)R41".deg. packing structure. XPS measurements showed that CPT SAMs at room temperature were formed via chemical reactions between the sulfur atoms and gold surfaces. TDS measurements showed two dominant TD peaks for the decomposed fragments (C_5H_9 "+, m/e = 69) generated via C-S bond cleavage and the parent molecular species (C_5H_9SH"+, m/e = 102) derived from a recombination of the chemisorbed thiolates and hydrogen atoms near 440 K. Interestingly, dimerization of sulfur atoms in n-alkanethiol SAMs usually occurs during thermal desorption and the same reaction did not happen for CPT SAMs, which may be due to the steric hindrance of cyclic rings of the CPT molecules. In this study, we demonstrated that the alicyclic ring of organic thiols strongly affected the surface structure and thermal desorption behavior of SAMs, thus providing a good method for controlling chemical and physical properties of organic thiol SAMs

Passivation of hexagonal SiC surfaces by hydrogen termination

International Nuclear Information System (INIS)

Seyller, Thomas

2004-01-01

Surface hydrogenation is a well established technique in silicon technology. It is easily accomplished by wet-chemical procedures and results in clean and unreconstructed surfaces, which are extremely low in charged surface states and stable against oxidation in air, thus constituting an ideal surface preparation. As a consequence, methods for hydrogenation have been sought for preparing silicon carbide (SiC) surfaces with similar well defined properties. It was soon recognized, however, that due to different surface chemistry new ground had to be broken in order to find a method leading to the desired monatomic hydrogen saturation. In this paper the results of H passivation of SiC surfaces by high-temperature hydrogen annealing will be discussed, thereby placing emphasis on chemical, structural and electronic properties of the resulting surfaces. In addition to their unique properties, hydrogenated hexagonal SiC {0001} surfaces offer the interesting possibility of gaining insight into the formation of silicon- and carbon-rich reconstructions as well. This is due to the fact that to date hydrogenation is the only method providing oxygen-free surfaces with a C to Si ratio of 1:1. Last but not least, the electronic properties of hydrogen-free SiC {0001} surfaces will be alluded to. SiC {0001} surfaces are the only known semiconductor surfaces that can be prepared in their unreconstructed (1 x 1) state with one dangling bond per unit cell by photon induced hydrogen desorption. These surfaces give indications of a Mott-Hubbard surface band structure

An infrared measurement of chemical desorption from interstellar ice analogues

Science.gov (United States)

Oba, Y.; Tomaru, T.; Lamberts, T.; Kouchi, A.; Watanabe, N.

2018-03-01

In molecular clouds at temperatures as low as 10 K, all species except hydrogen and helium should be locked in the heterogeneous ice on dust grain surfaces. Nevertheless, astronomical observations have detected over 150 different species in the gas phase in these clouds. The mechanism by which molecules are released from the dust surface below thermal desorption temperatures to be detectable in the gas phase is crucial for understanding the chemical evolution in such cold clouds. Chemical desorption, caused by the excess energy of an exothermic reaction, was first proposed as a key molecular release mechanism almost 50 years ago1. Chemical desorption can, in principle, take place at any temperature, even below the thermal desorption temperature. Therefore, astrochemical network models commonly include this process2,3. Although there have been a few previous experimental efforts4-6, no infrared measurement of the surface (which has a strong advantage to quantify chemical desorption) has been performed. Here, we report the first infrared in situ measurement of chemical desorption during the reactions H + H2S → HS + H2 (reaction 1) and HS + H → H2S (reaction 2), which are key to interstellar sulphur chemistry2,3. The present study clearly demonstrates that chemical desorption is a more efficient process for releasing H2S into the gas phase than was previously believed. The obtained effective cross-section for chemical desorption indicates that the chemical desorption rate exceeds the photodesorption rate in typical interstellar environments.

Hydrogen storage development

Energy Technology Data Exchange (ETDEWEB)

Thomas, G.J.; Guthrie, S.E. [Sandia National Labs., Livermore, CA (United States)

1998-08-01

A summary of the hydride development efforts for the current program year (FY98) are presented here. The Mg-Al-Zn alloy system was studied at low Zn levels (2--4 wt%) and midrange Al contents (40--60 wt%). Higher plateau pressures were found with Al and Zn alloying in Mg and, furthermore, it was found that the hydrogen desorption kinetics were significantly improved with small additions of Zn. Results are also shown here for a detailed study of the low temperature properties of Mg{sub 2}NiH{sub 4}, and a comparison made between conventional melt cast alloy and the vapor process material.

A study of semiconducting properties of hydrogen containing passive films

International Nuclear Information System (INIS)

Zeng, Y.M.; Luo, J.L.; Norton, P.R.

2004-01-01

Mott-Schottky and photoelectrochemical measurements were used to explore the effects of hydrogen and chloride ions on the electronic properties of the passive film on X70 micro-alloyed steel in a solution of 0.5 M NaHCO 3 . Mott-Schottky analyses have shown that hydrogen increases the capacitance and donor density, and decreases the flat band potential and the space charge layer thickness of the passive film. The photocurrent of the film is remarkably increased by hydrogen. The effects of hydrogen become more pronounced with an increase in the hydrogen charging current densities. Hydrogen has no noticeable effect on the band gap energy E g and the process by which hole-electron pairs are photo-generated in the film. The presence of chloride ions in the solution produces some similar effects on the electronic properties of the passive film to those observed with hydrogen, but reduces the photocurrent and increases the band gap energy of the film. No significant synergistic effects on the electronic properties of the passive film were observed in the presence of hydrogen and Cl - . These results provide very useful information for elucidating the mechanism by which hydrogen changes the properties of passive film and then promotes localized corrosion

Interaction of D2 with H2O amorphous ice studied by temperature-programmed desorption experiments.

Science.gov (United States)

Amiaud, L; Fillion, J H; Baouche, S; Dulieu, F; Momeni, A; Lemaire, J L

2006-03-07

The gas-surface interaction of molecular hydrogen D2 with a thin film of porous amorphous solid water (ASW) grown at 10 K by slow vapor deposition has been studied by temperature-programmed-desorption (TPD) experiments. Molecular hydrogen diffuses rapidly into the porous network of the ice. The D2 desorption occurring between 10 and 30 K is considered here as a good probe of the effective surface of ASW interacting with the gas. The desorption kinetics have been systematically measured at various coverages. A careful analysis based on the Arrhenius plot method has provided the D2 binding energies as a function of the coverage. Asymmetric and broad distributions of binding energies were found, with a maximum population peaking at low energy. We propose a model for the desorption kinetics that assumes a complete thermal equilibrium of the molecules with the ice film. The sample is characterized by a distribution of adsorption sites that are filled according to a Fermi-Dirac statistic law. The TPD curves can be simulated and fitted to provide the parameters describing the distribution of the molecules as a function of their binding energy. This approach contributes to a correct description of the interaction of molecular hydrogen with the surface of possibly porous grain mantles in the interstellar medium.

Hydrogen storage in carbon nanostruc

NARCIS (Netherlands)

Hirscher, M.; Becher, M.; Haluska, M.; Quintel, A.; Skakalova, V.; Choi, M.; Dettlaff-Weglikowska, U.; Roth, S.; Stepanek, I.; Bernier, P.; Leonhardt, A.; Fink, J.

2002-01-01

The paper gives a critical review of the literature on hydrogen storage in carbon nanostructures. Furthermore, the hydrogen storage of graphite, graphite nanofibers (GNFs), and single-walled carbon nanotubes (SWNTs) was measured by thermal desorption spectroscopy (TDS). The samples were ball milled

The electrochemistry and modelling of hydrogen storage materials

International Nuclear Information System (INIS)

Kalisvaart, W.P.; Vermeulen, P.; Ledovskikh, A.V.; Danilov, D.; Notten, P.H.L.

2007-01-01

Mg-based alloys are promising hydrogen storage materials because of the high gravimetric energy density of MgH 2 (7.6 wt.%). A major disadvantage, however, is its very slow desorption kinetics. It has been argued that, in contrast to the well-known rutile-structured Mg hydride, hydrided Mg-transition metal alloys have a much more open crystal structure facilitating faster hydrogen transport. In this paper, the electrochemical aspects of new Mg-Sc and Mg-Ti materials will be reviewed. Storage capacities as high as 6.5 wt.% hydrogen have been reached with very favourable discharge kinetics. A theoretical description of hydrogen storage materials has also been developed by our group. A new lattice gas model is presented and successfully applied to simulate the thermodynamic properties of various hydride-forming materials. The simulation results are expressed by parameters corresponding to several energy contributions, for example mutual atomic hydrogen interaction energies. A good fit of the lattice gas model to the experimental data is found in all cases

Revisiting the Hydrogen Storage Behavior of the Na-O-H System

Directory of Open Access Journals (Sweden)

Jianfeng Mao

2015-04-01

Full Text Available Solid-state reactions between sodium hydride and sodium hydroxide are unusual among hydride-hydroxide systems since hydrogen can be stored reversibly. In order to understand the relationship between hydrogen uptake/release properties and phase/structure evolution, the dehydrogenation and hydrogenation behavior of the Na-O-H system has been investigated in detail both ex- and in-situ. Simultaneous thermogravimetric-differential thermal analysis coupled to mass spectrometry (TG-DTA-MS experiments of NaH-NaOH composites reveal two principal features: Firstly, an H2 desorption event occurring between 240 and 380 °C and secondly an additional endothermic process at around 170 °C with no associated weight change. In-situ high-resolution synchrotron powder X-ray diffraction showed that NaOH appears to form a solid solution with NaH yielding a new cubic complex hydride phase below 200 °C. The Na-H-OH phase persists up to the maximum temperature of the in-situ diffraction experiment shortly before dehydrogenation occurs. The present work suggests that not only is the inter-phase synergic interaction of protic hydrogen (in NaOH and hydridic hydrogen (in NaH important in the dehydrogenation mechanism, but that also an intra-phase Hδ+… Hδ– interaction may be a crucial step in the desorption process.

Evidence for hydrogen-assisted recovery of cold-worked palladium: hydrogen solubility and mechanical properties studies

Directory of Open Access Journals (Sweden)

Maria Ferrer

2017-07-01

Full Text Available The influence of hydrogen as an agent to accelerate the thermal recovery of cold-worked palladium has been investigated. The techniques used to characterize the effects of hydrogen on the thermal recovery of palladium were hydrogen solubility and mechanical property measurements. Results show that the presence of modest amounts of hydrogen during annealing of cold-worked palladium does enhance the degree of thermal recovery, with a direct correlation between the amount of hydrogen during annealing and the degree of recovery. The results indicate that the damage resulting from cold-working palladium can be more effectively and efficiently reversed by suitable heat treatments in the presence of appropriate amounts of hydrogen, as compared to heat treatment in vacuum. The somewhat novel technique of using changes in the hydrogen solubility of palladium as an indicator of thermal recovery has been validated and complements the more traditional technique of mechanical property measurements.

Thermodesorption examination of interaction of hydrogen with traps in silver

International Nuclear Information System (INIS)

Gabis, I.E.; Kurdyumov, A.A.; Ovsvannikova, T.A.

1992-01-01

The authors have previously examined the interaction of hydrogen with silver by the methods of thermal desorption spectrometry (TDS) and hydrogen permeability. The results showed that the TDS spectra contained a high-temperature phase linked with hydrogen which left the volume of the specimen during heating. It was assumed that hydrogen was captured and released by structural defects acting as traps. These traps can be represented by vacancies and their clusters. In this work, the high-temperature desorption of hydrogen from silver was studied. The experimental setup consisted of an all-metal vacuum system, a time-of-flight mass spectrometer, a DVK-2M computing system, and a Camac system. The described model of a local equilibrium should be regarded only as a first approximation. The results provide unambiguous information on the processes of permeability and desorption, and make it possible to assume that the formation of the high-temperature phase in TD spectra was caused by the generation of hydrogen from the traps. The parameters of the interaction of hydrogen with the traps were determined by the concentration wave method. 7 refs., 2 figs

Hydrogen storage in hybrid of layered double hydroxides/reduced graphene oxide using spillover mechanism

International Nuclear Information System (INIS)

Ensafi, Ali A.; Jafari-Asl, Mehdi; Nabiyan, Afshin; Rezaei, Behzad; Dinari, Mohammad

2016-01-01

New efficient hydrogen storage hybrids were fabricated based on hydrogen spillover mechanism, including chemisorptions and dissociation of H_2 on the surface of LDH (layered double hydroxides) and diffusion of H to rGO (reduced graphene oxide). The structures and compositions of all of the hybrids (LDHs/rGO) have been verified using different methods including transmission electron microscopy, X ray diffraction spectroscopy, infrared spectroscopy and Brunauer–Emmett–Teller analysis. Then, the abilities of the LDHs/rGOs, as hydrogen spillover, were investigated by electrochemical methods. In addition, the LDHs/rGOs were decorated with palladium, using redox replacement process, and their hydrogen spillover properties were studied. The results showed that the hydrogen adsorption/desorption kinetics, hydrogen storage capacities and stabilities of Pd"#LDH/rGOs are better than Pd/rGO. Finally presence of different polymers (synthesis with monomers, 4–aminophenol, 4–aminothiophenol, o-phenylenediamine and p-phenylenediamine) at the surface of the Pd#LDH/rGOs on hydrogen storage were studied. The results showed that presence of o-phenylenediamine and p-phenylenediamine improves the kinetics of the hydrogen adsorption/desorption and increase the capacity of the hydrogen storage. - Highlights: • Efficient hydrogen storage sorbents are introduced. • The sorbents are synthesized based on hybrids of layered double hydroxide. • The compositions of all of the hybrids are verified using different methods. • Pd nanoparticles modified nanohybrids are investigated for hydrogen storage. • Presence of different polymers beside the hydrogen sorbents are investigated.

Reversible hydrogen storage by NaAlH4 confined within a titanium-functionalized MOF-74(Mg) nanoreactor.

Science.gov (United States)

Stavila, Vitalie; Bhakta, Raghunandan K; Alam, Todd M; Majzoub, Eric H; Allendorf, Mark D

2012-11-27

We demonstrate that NaAlH(4) confined within the nanopores of a titanium-functionalized metal-organic framework (MOF) template MOF-74(Mg) can reversibly store hydrogen with minimal loss of capacity. Hydride-infiltrated samples were synthesized by melt infiltration, achieving loadings up to 21 wt %. MOF-74(Mg) possesses one-dimensional, 12 Å channels lined with Mg atoms having open coordination sites, which can serve as sites for Ti catalyst stabilization. MOF-74(Mg) is stable under repeated hydrogen desorption and hydride regeneration cycles, allowing it to serve as a "nanoreactor". Confining NaAlH(4) within these pores alters the decomposition pathway by eliminating the stable intermediate Na(3)AlH(6) phase observed during bulk decomposition and proceeding directly to NaH, Al, and H(2), in agreement with theory. The onset of hydrogen desorption for both Ti-doped and undoped nano-NaAlH(4)@MOF-74(Mg) is ∼50 °C, nearly 100 °C lower than bulk NaAlH(4). However, the presence of titanium is not necessary for this increase in desorption kinetics but enables rehydriding to be almost fully reversible. Isothermal kinetic studies indicate that the activation energy for H(2) desorption is reduced from 79.5 kJ mol(-1) in bulk Ti-doped NaAlH(4) to 57.4 kJ mol(-1) for nanoconfined NaAlH(4). The structural properties of nano-NaAlH(4)@MOF-74(Mg) were probed using (23)Na and (27)Al solid-state MAS NMR, which indicates that the hydride is not decomposed during infiltration and that Al is present as tetrahedral AlH(4)(-) anions prior to desorption and as Al metal after desorption. Because of the highly ordered MOF structure and monodisperse pore dimensions, our results allow key template features to be identified to ensure reversible, low-temperature hydrogen storage.

Hydrogen storage of Mg1−xMxH2 (M = Ti, V, Fe) studied using first-principles calculations

International Nuclear Information System (INIS)

Bhihi, M.; Lakhal, M.; Benyoussef, A.; El Kenz, A.; Labrim, H.; Mounkachi, O.; Hlil, E.K.

2012-01-01

In this work, the hydrogen storage properties of the Mg-based hydrides, i.e., Mg 1−x M x H 2 (M = Ti, V, Fe, 0 ≤ x ≤ 0.1), are studied using the Korringa—Kohn—Rostoker (KKR) calculation with the coherent potential approximation (CPA). In particular, the nature and concentrations of the alloying elements and their effects are studied. Moreover, the material's stability and hydrogen storage thermodynamic properties are discussed. In particular, we find that the stability and the temperature of desorption decrease without significantly affecting the storage capacities

Local stabilization of single-walled carbon nanotubes on Si(100)-2 x 1:H via nanoscale hydrogen desorption with an ultrahigh vacuum scanning tunnelling microscope

International Nuclear Information System (INIS)

Albrecht, Peter M; Lyding, Joseph W

2007-01-01

An ultrahigh vacuum scanning tunnelling microscope (UHV-STM) was used to modify the interface between isolated ∼10 A-diameter single-walled carbon nanotubes (SWNTs) and the hydrogen-passivated Si(100) surface. Room-temperature UHV-STM desorption of hydrogen at the SWNT/H-Si(100) interface resulted in the local mechanical stabilization of tubes originally perturbed by the rastered STM tip under nominal imaging conditions. For the section of the SWNT contacted by depassivated Si, a topographic depression of 1.5 A (1 A) was measured in the case of parallel (nearly perpendicular) alignment between the tube axis and the Si dimer rows, in agreement with existing first-principles calculations. The compatibility of hydrogen-resist UHV-STM nanolithography with SWNTs adsorbed on H-Si(100) would enable the atomically precise placement of single molecules in proximity to the tube for the bottom-up fabrication of molecular electronic devices

Study of the mechanisms of heavy-ion induced desorption on accelerator-relevant materials; Untersuchung der Mechanismen schwerioneninduzierter Desorption an beschleunigerrelevanten Materialien

Energy Technology Data Exchange (ETDEWEB)

Bender, Markus

2008-02-22

The ion beam loss induced desorption is a performance limitation for low charge state heavy ion accelerators. If charge exchanged projectile ions get lost onto the beam pipe, desorption of gas is stimulated resulting in a pressure increase inside of the synchrotron and thus, a dramatically reduction of the beam life time. To minimize the amount of desorbed gas an experimental program has been started to measure the desorption yields (released gas molecules per incident ion) of various materials and different projectile ions. The present work is a contribution to the understanding of the physical processes behind the ion beam loss induced desorption. The yield measurements by the pressure rise method have been combined for the rst time with in situ ion beam analysis technologies such as ERDA and RBS. With this unique method the desorption behavior of a sample can be correlated to its surface and bulk properties. The performed experiments with 1,4 MeV/u Xenon-Ions show that the ion induced desorption is mainly a surface effect. Sputtered oxide layers or impurities do not contribute to the desorbed gas significantly. Nevertheless bulk properties play an important role in the desorption strength. Pure metallic samples desorb less gas than isolating materials under swift heavy ion irradiation. From the experimental results it was possible to estimate the desorption yields of various materials under ion bombardment by means of an extended inelastic thermal-spike-model. The extension is the combination of the thermal-spike's temperature map with thermal desorption. Within this model the ion induced desorption can be regarded as the release of adsorbates from a transient overheated spot on the samples surface around the ion impact. Finally a copper substrate with a gold coated surface was developed and proposed as a suitable material for a beam loss collimator with minimum desorption to ensure the performance of GSI's SIS18 in high current beam operation. (orig.)

Hydrogen storing and electrical properties of hyperbranched polymers-based nanoporous materials

International Nuclear Information System (INIS)

Abdel Rehim, Mona H.; Ismail, Nahla; Badawy, Abd El-Rahman A.A.; Turky, Gamal

2011-01-01

Highlights: · The hydrogen storage capacity of hyperbranched P-Urea, PAMAM and PAMAM and VO x is studied and electrical properties of the samples are also investigated; the measurements showed complete insulating behavior at hydrogenation measuring temperature. These investigations ensure that the polymer conductivity does not play a role in hydrogen uptake, also hyperbranched polymers are promising materials for hydrogen storage. · Electrical properties measurements for the samples showed complete insulating behavior at hydrogenation measuring temperature. · These investigations ensure that the polymer conductivity does not play a role in hydrogen uptake, also hyperbranched polymers are promising materials for hydrogen storage. - Abstract: Hydrogen storage and electrical properties of different hyperbranched polymer systems beside a nanocomposite are studied. The polymers examined are aliphatic hyperbranched poly urea (P-Urea), polyamide amine (PAMAM) and polyamide amine/vanadium oxide (PAMAM/VO x ) nanocomposite. At 80 K and up to 20 bar hydrogen pressure, the hydrogen storage capacity of hyperbranched P-Urea reached 1.6 wt%, 0.9 wt% in case of PAMAM and 0.6 wt% for VO x . The hydrogen storage capacity significantly enhanced when PAMAM and VO x form a nanocomposite and increased up to 2 wt%. At 298 K and up to 20 bar, all the samples did not show measurable hydrogen uptake. Electrical properties of the samples are also investigated; the measurements showed complete insulating behavior at hydrogenation measuring temperature. These investigations ensure that the polymer conductivity does not play a role in hydrogen uptake, also hyperbranched polymers are promising materials for hydrogen storage.

Studies of the effects of TiCl3 in LiBH4/CaH2/TiCl3 reversible hydrogen storage system

International Nuclear Information System (INIS)

Liu Dongan; Yang Jun; Ni Jun; Drews, Andy

2012-01-01

Highlights: ► We systematically studied the effects of TiCl 3 in LiBH 4 /CaH 2 /TiCl 3 hydrogen storage system. ► It is found that adding 0.25 TiCl 3 produces fully reversible hydrogen absorption and desorption and a lower desorption temperature. ► LiCl experiences four different states, i.e. “formed-solid solution-molten solution-precipitation”, in the whole desorption process of the system. ► The incorporation of LiCl into LiBH 4 forms more viscous molten LiBH 4 ·LiCl, leading to fast kinetics. ► The precipitation and re-incorporation of LiCl into LiBH 4 lead to a fully reversible complex hydrogen storage system. - Abstract: In the present study, the effects of TiCl 3 on desorption kinetics, absorption/desorption reversibility, and related phase transformation processes in LiBH 4 /CaH 2 /TiCl 3 hydrogen storage system was studied systematically by varying its concentration (x = 0, 0.05, 0.15 and 0.25). The results show that LiCl forms during ball milling of 6LiBH 4 /CaH 2 /xTiCl 3 and that as temperature increases, o-LiBH 4 transforms into h-LiBH 4 , into which LiCl incorporates, forming solid solution of LiBH 4 ·LiCl, which melts above 280 °C. Molten LiBH 4 ·LiCl is more viscous than molten LiBH 4 , preventing the clustering of LiBH 4 and the accompanied agglomeration of CaH 2 , and thus preserving the nano-sized phase arrangement formed during ball milling. Above 350 °C, the molten solution LiBH 4 ·LiCl further reacts with CaH 2 , precipitating LiCl. The main hydrogen desorption reaction is between molten LiBH 4 ·LiCl and CaH 2 and not between molten LiBH 4 and CaH 2 . This alters the hydrogen reaction thermodynamics and lowers the hydrogen desorption temperature. In addition, the solid–liquid nano-sized phase arrangement in the nano-composites improves the hydrogen reaction kinetics. The reversible incorporation/precipitation of LiCl at the hydrogen reaction temperature and during temperature cycling makes the 6LiBH 4 /CaH 2 /0.25TiCl 3

Surface Structures and Thermal Desorption Behaviors of Cyclopentanethiol Self-Assembled Monolayers on Au(111)

Energy Technology Data Exchange (ETDEWEB)

Kang, Hun Gu; Kim, You Young; Park, Tae Sun; Noh, Jae Geun [Hanyang University, Seoul (Korea, Republic of); Park, Joon B. [Chonbuk National University, Jeonju (Korea, Republic of); Ito, Eisuke; Hara, Masahiko [RIKEN-HYU Collaboration Center, Saitama (Japan)

2011-04-15

The surface structures, adsorption conditions, and thermal desorption behaviors of cyclopentanethiol (CPT) self-assembled monolayers (SAMs) on Au(111) were investigated by scanning tunneling microscopy (STM), X-ray photoelectron spectroscopy (XPS), and thermal desorption spectroscopy (TDS). STM imaging revealed that although the adsorption of CPT on Au(111) at room temperature generates disordered SAMs, CPT molecules at 50 .deg. C formed well-ordered SAMs with a (2√3 x √5)R41{sup .}deg. packing structure. XPS measurements showed that CPT SAMs at room temperature were formed via chemical reactions between the sulfur atoms and gold surfaces. TDS measurements showed two dominant TD peaks for the decomposed fragments (C{sub 5}H{sub 9} {sup +}, m/e = 69) generated via C-S bond cleavage and the parent molecular species (C{sub 5}H{sub 9}SH{sup +}, m/e = 102) derived from a recombination of the chemisorbed thiolates and hydrogen atoms near 440 K. Interestingly, dimerization of sulfur atoms in n-alkanethiol SAMs usually occurs during thermal desorption and the same reaction did not happen for CPT SAMs, which may be due to the steric hindrance of cyclic rings of the CPT molecules. In this study, we demonstrated that the alicyclic ring of organic thiols strongly affected the surface structure and thermal desorption behavior of SAMs, thus providing a good method for controlling chemical and physical properties of organic thiol SAMs.

Thermoanalytical investigation of the hydrogen absorption behaviour of Sm2Fe17-xGax at high hydrogen pressures

International Nuclear Information System (INIS)

Handstein, A.; Kubis, M.; Gebel, B.; Mueller, K.-H.; Schultz, L.; Gutfleisch, O.; Harris, I.R.; Birmingham Univ.

1998-01-01

The complete disproportionation of Sm 2 Fe 17-x Ga x during annealing in hydrogen is hindered due to an increased stability of the compounds with a higher Ga content (x ≥ 1). Therefore the HD process as the first step of HDDR (hydrogenation-disproportionation-desorption-recombination) has to be carried out at a high hydrogen pressure for x ≥ 1. The hydrogen absorption behaviour of Sm 2 Fe 17-x Ga x (x = 0, 0.5, 1 and 2) was investigated by means of hydrogen differential thermal analysis (HDTA) and high pressure differential scanning calorimetry (HPDSC) at hydrogen pressures up to 70 bar. A dependency of hydrogenation and disproportionation temperatures on hydrogen pressure and Ga content was found. The comparison with other substituents (M = Al and Si) instead of M = Ga showed an increased stability of Sm 2 Fe 17-x M x compounds against disproportionation by hydrogen in the sequence Al, Ga and Si. The Curie temperatures of the interstitially hydrogenated Th 2 Zn 17 -type materials increase with the hydrogen pressure. In order to produce coercive and thermally stable Sm 2 Fe 15 Ga 2 C y powder by means of the HDDR process, we recombined material disproportionated at different hydrogen pressures. Preliminary results of magnetic properties of this HDDR treated and gas-carburized Sm 2 Fe 15 Ga 2 C y are discussed. (orig.)

Hydrogen storage in binary and ternary Mg-based alloys: A comprehensive experimental study

Energy Technology Data Exchange (ETDEWEB)

Kalisvaart, W.P.; Harrower, C.T.; Haagsma, J.; Zahiri, B.; Luber, E.J.; Ophus, C.; Mitlin, D. [Chemical and Materials Engineering, University of Alberta and National Research Council Canada, National Institute for Nanotechnology, T6G 2V4, Edmonton, Alberta (Canada); Poirier, E.; Fritzsche, H. [National Research Council Canada, SIMS, Canadian Neutron Beam Centre, Chalk River Laboratories, Chalk River, Ontario, K0J 1J0 (Canada)

2010-03-15

This study focused on hydrogen sorption properties of 1.5 {mu}m thick Mg-based films with Al, Fe and Ti as alloying elements. The binary alloys are used to establish as baseline case for the ternary Mg-Al-Ti, Mg-Fe-Ti and Mg-Al-Fe compositions. We show that the ternary alloys in particular display remarkable sorption behavior: at 200 C the films are capable of absorbing 4-6 wt% hydrogen in seconds, and desorbing in minutes. Furthermore, this sorption behavior is stable over cycling for the Mg-Al-Ti and Mg-Fe-Ti alloys. Even after 100 absorption/desorption cycles, no degradation in capacity or kinetics is observed. For Mg-Al-Fe, the properties are clearly worse compared to the other ternary combinations. These differences are explained by considering the properties of all the different phases present during cycling in terms of their hydrogen affinity and catalytic activity. Based on these considerations, some general design principles for Mg-based hydrogen storage alloys are suggested. (author)

Study of Supported Nickel Catalysts Prepared by Aqueous Hydrazine Method. Hydrogenating Properties and Hydrogen Storage: Support Effect. Silver Additive Effect; Catalyseurs de nickel supportes prepares par la methode de l'hydrazine aqueuse. Proprietes hydrogenantes et stockage d'hydrogene. Effet du support. Effet de l'ajout d'argent

Energy Technology Data Exchange (ETDEWEB)

Wojcieszak, R

2006-06-15

We have studied Ni or NiAg nano-particles obtained by the reduction of nickel salts (acetate or nitrate) by hydrazine and deposited by simple or EDTA-double impregnation on various supports ({gamma}-Al{sub 2}O{sub 3}, amorphous or crystallized SiO{sub 2}, Nb{sub 2}O{sub 5}, CeO{sub 2} and carbon). Prepared catalysts were characterized by different methods (XRD, XPS, low temperature adsorption and desorption of N{sub 2}, FTIR and FTIR-Pyridine, TEM, STEM, EDS, H{sub 2}-TPR, H{sub 2}-adsorption, H{sub 2}-TPD, isopropanol decomposition) and tested in the gas phase hydrogenation of benzene or as carbon materials in the hydrogen storage at room temperature and high pressure. The catalysts prepared exhibited better dispersion and activity than classical catalysts. TOF's of NiAg/SiO{sub 2} or Ni/carbon catalysts were similar to Pt catalysts in benzene hydrogenation. Differences in support acidity or preparation method and presence of Ag as metal additive play a crucial role in the chemical reduction of Ni by hydrazine and in the final properties of the materials. Ni/carbon catalysts could store significant amounts of hydrogen at room temperature and high pressure (0.53%/30 bars), probably through the hydrogen spillover effect. (author)

Shape-dependent hydrogen-storage properties in Pd nanocrystals: which does hydrogen prefer, octahedron (111) or cube (100)?

Science.gov (United States)

Li, Guangqin; Kobayashi, Hirokazu; Dekura, Shun; Ikeda, Ryuichi; Kubota, Yoshiki; Kato, Kenichi; Takata, Masaki; Yamamoto, Tomokazu; Matsumura, Syo; Kitagawa, Hiroshi

2014-07-23

Pd octahedrons and cubes enclosed by {111} and {100} facets, respectively, have been synthesized for investigation of the shape effect on hydrogen-absorption properties. Hydrogen-storage properties were investigated using in situ powder X-ray diffraction, in situ solid-state (2)H NMR and hydrogen pressure-composition isotherm measurements. With these measurements, it was found that the exposed facets do not affect hydrogen-storage capacity; however, they significantly affect the absorption speed, with octahedral nanocrystals showing the faster response. The heat of adsorption of hydrogen and the hydrogen diffusion pathway were suggested to be dominant factors for hydrogen-absorption speed. Furthermore, in situ solid-state (2)H NMR detected for the first time the state of (2)H in a solid-solution (Pd + H) phase of Pd nanocrystals at rt.

Production method of hydrogen storage alloy electrode and hydrogen storage alloy for rechageable battery; Suiso kyuzo gokin denkyoku oyobi chikudenchiyo suiso kyuzo gokin no seizo hoho

Energy Technology Data Exchange (ETDEWEB)

Mizutaki, F.; Ishimaru, M.

1995-04-07

This invention relates to the hydrogen storage alloy electrode in which the misch metal-nickel system hydrogen storage alloy is employed. The grain of the hydrogen storage alloy is controlled so as to reduce the dendrite cell size. Since the hydrogen storage alloy having such small dendrite cell size has no part where the metal structure is too brittle, the alloy has a sufficient mechanical strength. It can stand for the swell and shrink stress associated with the sorption and desorption of hydrogen. The disintegration, therefore, due to the cracking of the alloy is hardly to take place. In addition, the quenching of molten alloy at a cooling rate of 1000{degree}C/sec or faster suppresses the occurrence of segregation of any alloy element at the grain boundary, making it possible to produce the homogeneous and mechanically strong alloy. In other words, it can be achieved to produce a hydrogen storage alloy electrode having an excellent cycle property. 4 figs., 1 tab.

The kinetic isotope effect of hydrogen, deuterium and tritium absorbed and desorbed by titanium

International Nuclear Information System (INIS)

Huang Gang; Cao Xiaohua; Long Xinggui

2008-06-01

p-t curves of hydrogen, deuterium and tritium absorption at 550-750 degree C and desorption at 350-550 degree C by titanium were investigated. The rate constants of absorption and desorption for hydrogen, deuterium and tritium on each temperature are determined and the activation energy values obtained by this analysis are (55.6 ± 2.4) kJ·mol -1 , (110.2 ± 3.0) kJ·mol -1 and (155.5 ± 3.2) kJ·mol -1 for absorption and (27.1±0.4) KJ·mol -1 , (42.3 ± 1.9) kJ·mol -1 and (62.1±1.6) kJ·mol -1 for desorption respectively. The activation energy value of tritium absorption is highest which shows titanium tritiation is hardest. The activation energy value of tritium desorption is highest and it also can prove that titanium tritide is stablest. There are remarkable kinetic hydrogen isotope effects when titanium absorb and desorb hydrogen, deuterium and tritium. (authors)

Hydrogen storage in Mg: a most promising material

International Nuclear Information System (INIS)

Jain, I.P.; Jain, A.; Lal, C.

2009-01-01

hydrides stand as promising candidate for competitive hydrogen storage with reversible hydrogen capacity up to 7.6 wt% for on board applications. Efforts have been devoted to these materials to decrease their desorption temperature, enhance the kinetics and cycle life. The kinetics has been improved by adding an appropriate catalyst into the system as well as by ball milling that introduces defects with improved surface properties. The studies reported promising results, such as improved kinetics and lower desorption temperatures, however, the state of the art materials are still far from meeting the aimed target for their transport applications. Therefore further research work is needed to achieve the goal by improving development on hydrogenation, thermal and cyclic behavior of metal hydrides. In the present article the possibility of commercialization of Mg based alloys has been discussed. (author)

Mutual Effects of Hydrogenation and Deformation in Ti-Nb Alloys

National Research Council Canada - National Science Library

Zander, D

2002-01-01

...), transmission electron microscopy (TEM), thermal desorption spectroscopy (TDS), and microhardness tests, the influence of hydrogen at high fugacities on the phase stability, desorption behavior, and microhardness in Ti-Nb (20 to 45 wt pct Nb...

Complex hydrides for hydrogen storage

Science.gov (United States)

Zidan, Ragaiy

2006-08-22

A hydrogen storage material and process of forming the material is provided in which complex hydrides are combined under conditions of elevated temperatures and/or elevated temperature and pressure with a titanium metal such as titanium butoxide. The resulting fused product exhibits hydrogen desorption kinetics having a first hydrogen release point which occurs at normal atmospheres and at a temperature between 50.degree. C. and 90.degree. C.

Micro study of the structural modifications induced by absorption of hydrogen in LaNi4.25Co0.75

International Nuclear Information System (INIS)

Latroche, M.; Joubert, J.-M.; Percheron-Guegan, A.

2000-01-01

Many intermetallic elements (rare earth gold transition metals) have significant properties that will affect the adsorption of hydrogen. Within the properties, particularly of those composed of AB n , hydrogenation is affected by temperature and environmental pressure. Moreover, the reaction can also be done in electrochemical medium. These remarkable properties made it possible to develop batteries of standard nickel hydride which today largely replace the Nickel Cadmium batteries. However, mechanisms brought into play at an atomic scale during the cycles of absorption-desorption are still badly known. We present here a study by X-ray diffraction of substitute compositions for LaNi 4.25 Co 0.75 cobalt subjected to the absorption effects of hydrogen. The evolutions of profile E lines of elements before and after cycling are studied and compared

Surface properties of hydrogenated nanodiamonds: a chemical investigation.

Science.gov (United States)

Girard, H A; Petit, T; Perruchas, S; Gacoin, T; Gesset, C; Arnault, J C; Bergonzo, P

2011-06-28

Hydrogen terminations (C-H) confer to diamond layers specific surface properties such as a negative electron affinity and a superficial conductive layer, opening the way to specific functionalization routes. For example, efficient covalent bonding of diazonium salts or of alkene moieties can be performed on hydrogenated diamond thin films, owing to electronic exchanges at the interface. Here, we report on the chemical reactivity of fully hydrogenated High Pressure High Temperature (HPHT) nanodiamonds (H-NDs) towards such grafting, with respect to the reactivity of as-received NDs. Chemical characterizations such as FTIR, XPS analysis and Zeta potential measurements reveal a clear selectivity of such couplings on H-NDs, suggesting that C-H related surface properties remain dominant even on particles at the nanoscale. These results on hydrogenated NDs open up the route to a broad range of new functionalizations for innovative NDs applications development. This journal is © the Owner Societies 2011

Release enhancement of tritium from graphite by addition of hydrogen

International Nuclear Information System (INIS)

Saeki, Masakatsu; Masaki, N.M.

1989-01-01

The release behavior of tritium from graphite was studied in pure He and He + H 2 atmosphere. The release from powdered graphite was significantly enhanced in hydrogen environment. Apparent diffusion coefficients of tritium in graphite also became much higher in an atmosphere containing hydrogen than values obtained in pure helium atmosphere. A careful investigation of the release processes resulted in the conclusion that the most important process of tritium behaviour in graphite was diffusion, but the desorption process of tritium from the surface played a significant role. The enhancement of the desorption process was controlled by atomic hydrogen. (orig.)

Density Functional Theory Study of the Interaction of Hydrogen with Li6C60.

Science.gov (United States)

Wang, Qian; Jena, Puru

2012-05-03

Hydrogen storage properties of Li-coated C60 fullerene have been studied using density functional theory within the local density as well as generalized gradient approximation. Hydrogen atoms are found to bind to Li6C60 in two distinct forms, with the first set attaching to C atoms, not linked to Li, in atomic form. Once all such C atoms are saturated with hydrogen, the second set of hydrogen atoms bind quasi-molecularly to the Li atoms, five of which remain in the exohedral and the sixth in the endohedral position. The corresponding hydrogen gravimetric density in Li6C60H40 is 5 wt %. Desorption of hydrogen takes place in succession, the ones bound quasi-molecularly desorbing at a temperature lower than the ones bound atomically. The results are compared with the recent experiment on hydrogen adsorption in Li6C60.

Conceptual design of hydrogen isotopes chromatographic separation system with super large capacity

International Nuclear Information System (INIS)

Xie Bo; Weng Kuiping; Liu Yunnu; Hou Jianping

2012-01-01

A super large capacity hydrogen isotopes separation system, including total plan, unit (including making and purification of gas, three-grade chromatographic columns, gas loop and auto-control, and carrier recovery) and experimental scheme, had been designed on the basis of a series of hydrogen-deuterium experiments by temperature programmed de- sorption. The characteristic of the system was that desorption kinetic parameters could be directly calculated from the hydrogen isotope separation desorption spectra information. In other words, the complicated dynamic process of separation could be described by the desorption rate equation, shape parameter and desorption activation energy calculation on the condition of the experimental data and appropriate assumptions (equilibrium and adsorption, uniform surface). In previous work, an experimental series of operation to verify the successive enrichment of D 2 from a H 2 -D 2 mixture, the production of the deuterium from natural hydrogen and the recovery of tritium such as from the nuclear heavy-water were carried out using MS5A at 77 K. This work was only conceptual design, so it was necessary to identify the availability of super large capacity system by experiment. (authors)

The effects of low fugacity hydrogen in duplex- and beta-annealed Ti-6Al-4V alloy

International Nuclear Information System (INIS)

Tal-Gutelmacher, E.; Eliezer, D.; Eylon, D.

2004-01-01

Due to its excellent combination of a high strength/weight ratio and good corrosion behavior, Ti-6Al-4V alloys are ranked among the most important advanced materials for a variety of aerospace, chemical engineering, biomaterials, marine and commercial applications. However, in many of these technological applications, this alloy is exposed to environments which can act as sources of hydrogen, and severe problems may arise based on its susceptibility to hydrogen embrittlement. Even small hydrogen concentrations might lead to failure. Consequently, a comprehensive knowledge of hydrogen-trapping interactions is necessary to better understand the trapping mechanisms, the types of the trap sites, the trapped hydrogen content, in order to determine the safe service conditions of this alloy in the aerospace industry. The objective of this paper is to investigate the role of microstructure on hydrogen absorption/desorption behavior in Ti-6Al-4V alloy, with specific emphasis on the nature of the interaction between microstructural traps and hydrogen atoms. The effect of low fugacity hydrogen on the microstructure is studied using X-ray diffraction (XRD), and electron microscopy (SEM and TEM), while the absorption and desorption characteristics are determined by means of a hydrogen determinator and thermal desorption spectroscopy (TDS), respectively. The role of microstructure on hydrogen absorption and desorption behavior is discussed in detail

Sorption properties of nanocrystalline metal hydrides for the storage of hydrogen; Sorptionseigenschaften von nanokristallinen Metallhydriden fuer die Wasserstoffspeicherung

Energy Technology Data Exchange (ETDEWEB)

Oelerich, W.

2000-07-01

For the utilisation of hydrogen in emission-free automobiles new nanostructured Mg-based metal hydrides were developed. These materials show significantly faster absorption and desorption kinetics, which can be even further enhanced by additions of suitable catalysts. Contrary to conventional magnesium powder, hydrogenation at room temperature is demonstrated for the first time. During dehydrogenation at 250 C a desorption rate of 3 to 8 kW/kg with a capacity of 2.5 kWh/kg is achieved, that fulfills the technical requirements for automobile application. (orig.) [German] Im Hinblick auf den Einsatz von Wasserstoff in emissionsfreien Kraftfahrzeugen wurden neuartige nanostrukturierte Metallhydride auf Basis von Magnesium hergestellt. Diese Materialien zeigen eine deutlich schnellere Absorptions- und Desorptionskinetik, die sich durch den Zusatz von geeigneten Katalysatoren noch weiter steigern laesst. Im Gegensatz zu konventionellem Magnesiumpulver konnte erstmals eine Hydrierung bei Raumtemperatur demonstriert werden. Bei der Dehydrierung bei 250 C wird eine Desorptionsrate von 3 bis 8 kW/kg bei einer Kapazitaet von 2,5 kWh/kg erreicht, die die technischen Leistungsanforderungen von Kraftfahrzeugen erfuellt. (orig.)

Hydrogen Sorption Performance of Pure Magnesium during Continued Cycling

DEFF Research Database (Denmark)

Vigeholm, B.; Kjøller, John; Larsen, B.

1983-01-01

Preliminary investigations of the hydrogen absorption - desorption by commercially pure magnesium powder under continuous operation show little or no reduction in hydrogen capacity up to 70 cycles and high temperature exposure exceeding 1200 h. Absorption was studied at 260°–425°C and hydrogen...

Hydrogen storage properties of metallic hydrides

International Nuclear Information System (INIS)

Latroche, M.; Percheron-Guegan, A.

2005-01-01

Nowadays, energy needs are mainly covered by fossil energies leading to pollutant emissions mostly responsible for global warming. Among the different possible solutions for greenhouse effect reduction, hydrogen has been proposed for energy transportation. Indeed, H 2 can be seen as a clean and efficient energy carrier. However, beside the difficulties related to hydrogen production, efficient high capacity storage means are still to be developed. Many metals and alloys are able to store large amounts of hydrogen. This latter solution is of interest in terms of safety, global yield and long term storage. However, to be suitable for applications, such compounds must present high capacity, good reversibility, fast reactivity and sustainability. In this paper, we will review the structural and thermodynamic properties of metallic hydrides. (authors)

Hydrogen passivation of electron trap in amorphous In-Ga-Zn-O thin-film transistors

International Nuclear Information System (INIS)

Hanyu, Yuichiro; Domen, Kay; Nomura, Kenji; Hiramatsu, Hidenori; Kamiya, Toshio; Kumomi, Hideya; Hosono, Hideo

2013-01-01

We report an experimental evidence that some hydrogens passivate electron traps in an amorphous oxide semiconductor, a-In-Ga-Zn-O (a-IGZO). The a-IGZO thin-film transistors (TFTs) annealed at 300 °C exhibit good operation characteristics; while those annealed at ≥400 °C show deteriorated ones. Thermal desorption spectra (TDS) of H 2 O indicate that this threshold annealing temperature corresponds to depletion of H 2 O desorption from the a-IGZO layer. Hydrogen re-doping by wet oxygen annealing recovers the good TFT characteristic. The hydrogens responsible for this passivation have specific binding energies corresponding to the desorption temperatures of 300–430 °C. A plausible structural model is suggested

Metal Hydride Nanoparticles with Ultrahigh Structural Stability and Hydrogen Storage Activity Derived from Microencapsulated Nanoconfinement.

Science.gov (United States)

Zhang, Jiguang; Zhu, Yunfeng; Lin, Huaijun; Liu, Yana; Zhang, Yao; Li, Shenyang; Ma, Zhongliang; Li, Liquan

2017-06-01

Metal hydrides (MHs) have recently been designed for hydrogen sensors, switchable mirrors, rechargeable batteries, and other energy-storage and conversion-related applications. The demands of MHs, particular fast hydrogen absorption/desorption kinetics, have brought their sizes to nanoscale. However, the nanostructured MHs generally suffer from surface passivation and low aggregation-resisting structural stability upon absorption/desorption. This study reports a novel strategy named microencapsulated nanoconfinement to realize local synthesis of nano-MHs, which possess ultrahigh structural stability and superior desorption kinetics. Monodispersed Mg 2 NiH 4 single crystal nanoparticles (NPs) are in situ encapsulated on the surface of graphene sheets (GS) through facile gas-solid reactions. This well-defined MgO coating layer with a thickness of ≈3 nm efficiently separates the NPs from each other to prevent aggregation during hydrogen absorption/desorption cycles, leading to excellent thermal and mechanical stability. More interestingly, the MgO layer shows superior gas-selective permeability to prevent further oxidation of Mg 2 NiH 4 meanwhile accessible for hydrogen absorption/desorption. As a result, an extremely low activation energy (31.2 kJ mol -1 ) for the dehydrogenation reaction is achieved. This study provides alternative insights into designing nanosized MHs with both excellent hydrogen storage activity and thermal/mechanical stability exempting surface modification by agents. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

The use of one-dimensional Niobate to improve MgH{sub 2} hydrogen sorption

Energy Technology Data Exchange (ETDEWEB)

Brum, M.C., E-mail: mbrum@metalmat.ufrj.br; Conceição, M.O.T. da; Jardim, P.M.; Santos, D.S. dos

2014-12-05

Highlights: • The 1-D Niobate W and Niobate C catalysts were synthesized. • The composites MgH{sub 2} + 5 wt.% catalysts were obtained by 20 min of mechanical milling. • The synthesized wired-like material 1-D Niobate W showed to be a promising catalyst. • A desorption capacity of 6.0 wt.%. of H{sub 2} was attained in 10 min with MgH{sub 2} + 5 wt.% 1-D Niobate W. - Abstract: A study was performed on the hydrogen absorption/desorption properties of MgH{sub 2} with the addition of Niobates synthesized by hydrothermal treatment of Nb{sub 2}O{sub 5} in 10 M NaOH. Scanning Electron Microscopy (SEM) and X-ray diffraction (XRD) were used to evaluate their synthesis and show the morphological and crystallographic differences between Nb{sub 2}O{sub 5} used as a precursor and the Niobates produced, the one-dimensional wired type, 1-D Niobate W and the cuboid one, Niobate C. The ball milling of MgH{sub 2} with the Niobates was performed within only 20 min and afterwards the Differential Scanning Calorimetry (DSC) examination of MgH{sub 2} + 1-D Niobate W and MgH{sub 2} + Niobate C showed the shifting of the peaks for both composites in comparison to pure MgH{sub 2}. The influence of the two different types of Niobates and also the Nb{sub 2}O{sub 5} on the hydrogen absorption/desorption capacity was evaluated at 350 °C. The higher absorption and desorption values were attained by the MgH{sub 2} + 5 wt.% 1-D Niobate W composite, reaching, in 10 min, approximately 5.0 wt.% and 6.0 wt.%, respectively. The possible mechanism involved in such property improvement upon adding niobium based catalysts with different morphology and structure was discussed.

Design and construction of thermal desorption measurement system for tritium contained materials

International Nuclear Information System (INIS)

Hara, M.; Hatano, Y.; Calderoni, P.; Shimada, M.

2014-01-01

The dual-mode thermal desorption analysis system was designed and built in Idaho National Laboratory (INL) to examine the evolution of the hydrogen isotope gas from materials. The system is equipped with a mass spectrometer for stable hydrogen isotopes and an ionization chamber for tritium components. The performance of the system built was tested with using tritium contained materials. The evolution of tritiated gas species from contaminated materials was measured successfully by using the system. (author)

Hydrogen absorption study of Ti-based alloys performed by melt-spinning

Energy Technology Data Exchange (ETDEWEB)

Ribeiro, R.M.; Lemus, L.F.; Santos, D.S. dos, E-mail: rafaella@metalmat.ufrj.br [Coordenacao dos Programas de Pos-Graduacao em Engenharia (PEMM/COPPEP/UFRJ), Rio de Janeiro, RJ (Brazil). Programa de Engenharia Metalurgica e de Materiais

2013-11-01

The hydrogen absorption and desorption of Ti{sub 53}Zr{sub 27}Ni{sub 20} icosahedral quasicrystal (ICQ) and Ti{sub 50}Ni{sub 50} shape memory alloy (SMA) melt-spun ribbons was studied. Samples were exposed to hydrogen gas at 623 K and 4 MPa for 1000 minutes. The total capacity of hydrogen obtained for Ti{sub 53}Zr{sub 27}Ni{sub 20} and Ti{sub 50}Ni{sub 50} was 3.2 and 2.4 wt. % respectively. The Thermal Desorption Spectrometry (TDS) of the hydrogenated alloys shows that both alloys start to desorb hydrogen around 750 K. X-ray diffraction (XRD) patterns, performed after hydrogenation, indicate a complete amorphization of the Ti{sub 53}Zr{sub 27}Ni{sub 20} i-phase alloy, while the Ti{sub 50}Ni{sub 50} alloy remained crystalline after hydride formation. (author)

Nickel foam/polyaniline-based carbon/palladium composite electrodes for hydrogen storage

International Nuclear Information System (INIS)

Skowronski, Jan M.; Urbaniak, Jan

2008-01-01

The sandwich-like nickel/palladium/carbon electrodes exhibiting ability to absorb hydrogen in alkaline solution are presented. Electrodes were prepared by successive deposition of palladium and polyaniline layers on nickel foam substrate followed by heat treatment to give Ni/Pd/C electrode. It was shown that thermal conversion of polymer into carbon layer and subsequent thermal activation of carbon component bring about the modification of the mechanism of reversible hydrogen sorption. It was proven that carbon layer, interacting with Pd catalyst, plays a considerable role in the process of hydrogen storage. In the other series of experiments, Pd particles were dispersed electrochemically on carbon coating leading to Ni/C/Pd system. The adding of the next carbon layer resulted in Ni/C/Pd/C electrodes. Electrochemical properties of the electrodes depend on both the sequence of Pd and C layers and the preparation/activation of carbon coating. Electrochemical behavior of sandwich-like electrodes in the reaction of hydrogen sorption/desorption was characterized in 6 M KOH using the cyclic voltammetry method and the results obtained were compared to those for Ni/Pd electrode. The anodic desorption of hydrogen from electrodes free and containing carbon layer was considered after the potentiodynamic as well as potentiostatic sorption of hydrogen. The influence of the sorption potential and the time of rest of electrodes at a cut-off circuit on the kinetics of hydrogen recovery were examined. The results obtained for Ni/Pd/C electrodes indicate that the displacement of hydrogen between C and Pd phase takes place during the rest at a cut-off circuit. Electrodes containing carbon layer require longer time for hydrogen electrosorption. On the other hand, the presence of carbon layer in electrodes is advantageous because a considerable longer retention of hydrogen is possible, as compared to Pd/Ni electrode. Hydrogen stored in sandwich-like electrodes can instantly be

Hydrogen storage in binary and ternary Mg-based alloys. A comprehensive experimental study

Energy Technology Data Exchange (ETDEWEB)

Kalisvaart, W.P.; Harrower, C.T.; Haagsma, J.; Zahiri, B.; Luber, E.J.; Ophus, C.; Miltin, D. [Alberta Univ., Edmonton (Canada); Poirier, E.; Fritzsche, H. [Canadian Neutron Beam Centre, Chalk River, ON (Canada)

2010-07-01

This study focuses on hydrogen sorption properties of cosputtered 1.5 micrometer thick Mg-based films with Al, Fe and Ti as alloying elements. We show that ternary Mg-Al-Ti and Mg-Fe-Ti alloys in particular display remarkable sorption behavior: at 200 C, the films are capable of absorbing 4-6 wt.% hydrogen in seconds, and desorbing in minutes. Furthermore, this sorption behavior is stable for over 100 ab- and desorption cycles for Mg-Al-Ti and Mg-Fe-Ti alloys. No degradation in capacity or kinetics is observed. Based on these observations, some general design principles for Mg-based hydrogen storage alloys are suggested. For Mg-Fe-Ti, encouraging preliminary results on multilayered systems are also presented. (orig.)

New perspectives in vacuum high voltage insulation. II. Gas desorption

CERN Document Server

Diamond, W T

1998-01-01

An examination has been made of gas desorption from unbaked electrodes of copper, niobium, aluminum, and titanium subjected to high voltage in vacuum. It has been shown that the gas is composed of water vapor, carbon monoxide, and carbon dioxide, the usual components of vacuum outgassing, plus an increased yield of hydrogen and light hydrocarbons. The gas desorption was driven by anode conditioning as the voltage was increased between the electrodes. The gas is often desorbed as microdischarges-pulses of a few to hundreds of microseconds-and less frequently in a more continuous manner without the obvious pulsed structure characteristic of microdischarge activity. The quantity of gas released was equivalent to many monolayers and consisted mostly of neutral molecules with an ionic component of a few percent. A very significant observation was that the gas desorption was more dependent on the total voltage between the electrodes than on the electric field. It was not triggered by field-emitted electrons but oft...

New vistas in the determination of hydrogen in aerospace engine metal alloys

Science.gov (United States)

Danford, M. D.

1986-01-01

The application of diffusion theory to the analysis of hydrogen desorption data has been studied. From these analyses, important information concerning hydrogen solubilities and the nature of the hydrogen distributions in the metal has been obtained. Two nickel base alloys, Rene' 41 and Waspaloy, and one ferrous alloy, 4340 steel, were studied in this work. For the nickel base alloys, it was found that the hydrogen distributions after electrolytic charging conformed closely to those which would be predicted by diffusion theory. The hydrogen distributions in electrolytically charged 4340 steel, on the other hand, were essentially uniform in nature, which would not be predicted by diffusion theory. Finally, it has been found that the hydrogen desorption is completely explained by the nature of the hydrogen distribution in the metal, and that the 'fast' hydrogen is not due to surface and subsurface hydride formation, as was originally proposed.

Comparative study of reversible hydrogen storage in alkali-doped fulleranes

Energy Technology Data Exchange (ETDEWEB)

Teprovich, Joseph A.; Knight, Douglas A.; Peters, Brent [Clean Energy Directorate – Savannah River National Laboratory, Aiken, SC 29801 (United States); Zidan, Ragaiy, E-mail: ragaiy.zidan@srnl.doe.gov [Clean Energy Directorate – Savannah River National Laboratory, Aiken, SC 29801 (United States)

2013-12-15

Highlights: ► Catalytic effect of alkali metals of fullerane formation. ► Hydrogen storage properties of alkali metal hydrides and fullerene composites. ► Novel intercalation of Na and Li in the fullerene lattice. ► Reversible phase transformation of C{sub 60} from fcc to bcc upon de/rehydrogenation. ► Potential to enable to the formation of other carbon based hydrogen storage systems. -- Abstract: In this report we describe and compare the hydrogen storage properties of lithium and sodium doped fullerenes prepared via a solvent-assisted mixing process. For the preparation of these samples either NaH or LiH was utilized as the alkali metal source to make material based on either a Na{sub 6}C{sub 60} or Li{sub 6}C{sub 60}. Both of the alkali-doped materials can reversibly absorb and desorb hydrogen at much milder conditions than the starting materials used to make them (decomposition temperatures of NaH > 420 °C, LiH > 670 °C, and fullerane > 500 °C). The hydrogen storage properties of the materials were compared by TGA, isothermal desorption, and XRD analysis. It was determined that the sodium-doped material can reversibly store 4.0 wt.% H{sub 2} while the lithium doped material can reversibly store 5.0 wt.% H{sub 2} through a chemisorption mechanism indicated by the formation and measurement of C–H bonds. XRD analysis of the material demonstrated that a reversible phase transition between fcc and bcc occurs depending on the temperature at which the hydrogenation is performed. In either system the active hydrogen storage material resembles a hydrogenated fullerene (fullerane)

Comparative study of reversible hydrogen storage in alkali-doped fulleranes

International Nuclear Information System (INIS)

Teprovich, Joseph A.; Knight, Douglas A.; Peters, Brent; Zidan, Ragaiy

2013-01-01

Highlights: ► Catalytic effect of alkali metals of fullerane formation. ► Hydrogen storage properties of alkali metal hydrides and fullerene composites. ► Novel intercalation of Na and Li in the fullerene lattice. ► Reversible phase transformation of C 60 from fcc to bcc upon de/rehydrogenation. ► Potential to enable to the formation of other carbon based hydrogen storage systems. -- Abstract: In this report we describe and compare the hydrogen storage properties of lithium and sodium doped fullerenes prepared via a solvent-assisted mixing process. For the preparation of these samples either NaH or LiH was utilized as the alkali metal source to make material based on either a Na 6 C 60 or Li 6 C 60 . Both of the alkali-doped materials can reversibly absorb and desorb hydrogen at much milder conditions than the starting materials used to make them (decomposition temperatures of NaH > 420 °C, LiH > 670 °C, and fullerane > 500 °C). The hydrogen storage properties of the materials were compared by TGA, isothermal desorption, and XRD analysis. It was determined that the sodium-doped material can reversibly store 4.0 wt.% H 2 while the lithium doped material can reversibly store 5.0 wt.% H 2 through a chemisorption mechanism indicated by the formation and measurement of C–H bonds. XRD analysis of the material demonstrated that a reversible phase transition between fcc and bcc occurs depending on the temperature at which the hydrogenation is performed. In either system the active hydrogen storage material resembles a hydrogenated fullerene (fullerane)

Li-Al-borohydride as a potential candidate for on-board hydrogen storage

Energy Technology Data Exchange (ETDEWEB)

Lindemann, Inge; Domenech Ferrer, Roger; Dunsch, Lothar; Schultz, Ludwig; Gutfleisch, Oliver [IFW Dresden, PO Box 270016, D-01171 Dresden (Germany); Filinchuk, Yaroslav [Swiss-Norwegian Beam Lines at ESRF, BP-220, 38043 Grenoble (France); Hagemann, Hans; Cerny, Radovan [University of Geneva, Crystallography and Physical Chemistry Department, 1211 Geneva (Switzerland)

2010-07-01

Recently, double-cation borohydride systems have attracted great interest. It was found that the desorption temperature of the borohydrides decreases with increasing electronegativity of the cation. Consequently, it is possible to tailor a feasible on-board hydrogen storage material by combination of appropriate cations. Li-Al-borohydride shows a desorption temperature suitable for applications ({approx} 70 C) combined with an high hydrogen density (17.2 wt.%). It was synthesised via high energy ball milling of AlCl{sub 3} and LiBH{sub 4}. The structure of the compound was obtained from high-resolution synchrotron powder diffraction and shows a unique complex structure within the borohydrides. The material was characterized by means of in-situ-Raman, DSC, TG and thermal desorption measurements to study its decomposition pathway. The desorption at {approx} 70 C results in the formation of LiBH{sub 4} while the high mass loss of about 20% points to the release of not only hydrogen but also diborane. This is right now the main drawback for applications because it hinders reversibility.

Sorption and desorption of indaziflam degradates in several agricultural soils

Directory of Open Access Journals (Sweden)

Diego Gonçalves Alonso

2016-04-01

Full Text Available ABSTRACT Processes regulating pesticide fate in the environment are influenced by the physicochemical properties of pesticides and soils. Sorption and desorption are important processes as they regulate the movement of pesticides in soil. Although sorption-desorption is widely studied for herbicides, studies involving their metabolites in soil are scarce. Sorption and desorption of indaziflam metabolites (indaziflam-triazinediamine (FDAT, indaziflam-triazine-indanone (ITI and indaziflam-carboxilic acid (ICA were investigated in six Brazilian (BRA soils and three United States (USA soils with different physicochemical properties. The Freundlich equation described sorption of the metabolites for all soils (R2 > 0.98; 1/n ~ 1. Sorption order (Kf was ITI > ICA > FDAT. Mean values of Kf,oc were 453, 289, and 81 (BRA and 444, 48, and 48 (USA for metabolites ITI, ICA, and FDAT respectively. Desorption was hysteretic for all metabolites in all soils. These results suggest that these metabolites fall in the classification range of mobile to moderately mobile in soils.

Hydrogen absorption/desorption characteristics of room temperature ...

Indian Academy of Sciences (India)

ZrMn2-Ni system; metal hydrides; hydrogen storage materials. ... where ∼ 2.5 to 2.9 H/F.U. can be reversibly stored under the ideal operating conditions. ... these are promising candidates for stationary and short range mobile applications.

Hydrogen passivation of electron trap in amorphous In-Ga-Zn-O thin-film transistors

Energy Technology Data Exchange (ETDEWEB)

Hanyu, Yuichiro, E-mail: y-hanyu@lucid.msl.titech.ac.jp; Domen, Kay [Materials and Structures Laboratory, Tokyo Institute of Technology, Yokohama (Japan); Nomura, Kenji [Frontier Research Center, Tokyo Institute of Technology, Yokohama (Japan); Hiramatsu, Hidenori; Kamiya, Toshio [Materials and Structures Laboratory, Tokyo Institute of Technology, Yokohama (Japan); Materials Research Center for Element Strategy, Tokyo Institute of Technology, Yokohama (Japan); Kumomi, Hideya [Materials Research Center for Element Strategy, Tokyo Institute of Technology, Yokohama (Japan); Hosono, Hideo [Materials and Structures Laboratory, Tokyo Institute of Technology, Yokohama (Japan); Frontier Research Center, Tokyo Institute of Technology, Yokohama (Japan); Materials Research Center for Element Strategy, Tokyo Institute of Technology, Yokohama (Japan)

2013-11-11

We report an experimental evidence that some hydrogens passivate electron traps in an amorphous oxide semiconductor, a-In-Ga-Zn-O (a-IGZO). The a-IGZO thin-film transistors (TFTs) annealed at 300 °C exhibit good operation characteristics; while those annealed at ≥400 °C show deteriorated ones. Thermal desorption spectra (TDS) of H{sub 2}O indicate that this threshold annealing temperature corresponds to depletion of H{sub 2}O desorption from the a-IGZO layer. Hydrogen re-doping by wet oxygen annealing recovers the good TFT characteristic. The hydrogens responsible for this passivation have specific binding energies corresponding to the desorption temperatures of 300–430 °C. A plausible structural model is suggested.

Thermodynamics of the hybrid interaction of hydrogen with palladium nanoparticles

NARCIS (Netherlands)

Griessen, R.P.; Strohfeldt, N.; Giessen, H.

2015-01-01

Palladium-hydrogen is a prototypical metal-hydrogen system. It is therefore not at all surprising that a lot of attention has been devoted to the absorption and desorption of hydrogen in nanosized palladium particles. Several seminal articles on the interaction of H with Pd nanocubes and

Hydrogenated dilute nitride semiconductors theory, properties, and applications

CERN Document Server

Ciatto, Gianluca

2015-01-01

""The electrical and optical properties of the technologically and scientifically important dilute nitride semiconductors are strongly influenced by the introduction of atomic hydrogen. This volume is an excellent summary and resource for the most recent understanding of experimental results and state-of-the-art theoretical studies of the formation, reversibility, and microscopic structure of nitrogen-hydrogen complexes in these materials. The book details how a wide variety of experimental techniques have provided a detailed understanding of the role of hydrogen. It is the premier sourc

Formation of Multiple-Phase Catalysts for the Hydrogen Storage of Mg Nanoparticles by Adding Flowerlike NiS.

Science.gov (United States)

Xie, Xiubo; Ma, Xiujuan; Liu, Peng; Shang, Jiaxiang; Li, Xingguo; Liu, Tong

2017-02-22

In order to enhance the hydrogen storage properties of Mg, flowerlike NiS particles have been successfully prepared by solvothermal reaction method, and are subsequently ball milled with Mg nanoparticles (NPs) to fabricate Mg-5 wt % NiS nanocomposite. The nanocomposite displays Mg/NiS core/shell structure. The NiS shell decomposes into Ni, MgS and Mg 2 Ni multiple-phases, decorating on the surface of the Mg NPs after the first hydrogen absorption and desorption cycle at 673 K. The Mg-MgS-Mg 2 Ni-Ni nanocomposite shows enhanced hydrogenation and dehydrogenation rates: it can quickly uptake 3.5 wt % H 2 within 10 min at 423 K and release 3.1 wt % H 2 within 10 min at 573 K. The apparent hydrogen absorption and desorption activation energies are decreased to 45.45 and 64.71 kJ mol -1 . The enhanced sorption kinetics of the nanocomposite is attributed to the synergistic catalytic effects of the in situ formed MgS, Ni and Mg 2 Ni multiple-phase catalysts during the hydrogenation/dehydrogenation process, the porthole effects for the volume expansion and microstrain of the phase transformation of Mg 2 Ni and Mg 2 NiH 4 and the reduced hydrogen diffusion distance caused by nanosized Mg. This novel method of in situ producing multiple-phase catalysts gives a new horizon for designing high performance hydrogen storage material.

Sorption-desorption characteristics of benzimidazole based fungicide 2-(4-fluorophenyl)-1h-benzimidazole on physicochemical properties of selected pakistani soils

International Nuclear Information System (INIS)

Ahmad, K.S.

2014-01-01

A batch equilibrium method has been utilized to investigate the sorption-desorption behavior of a versatile cost-effective fungicide2-(4-fluorophenyl)-1H-benzimidazole) FBNZ on four Pakistani soils geographically distant, from hilly to desert areas. FBNZ is a newly synthesized fungicide prepared in the laboratory and is cost effective than the commercially available fungicides. The adsorption and desorption data were fitted to the Freundlich equation, with values of na = 1, which points to a C-type isotherm. Sorption increases with soil organic carbon content, with greater degree of adsorption for hilly soil and least adsorption on sandy soil of Multan, Punjab. Desorption studies reveal that the adsorbed fungicide are firmly retained by soil particles and present a certain degree of irreversibility. The results indicate that the soil organic matters followed by clay content are the most important soil properties governing the fungicide sorption capacity. (author)

Moessbauer study of Mg-Ni(Fe) alloys processed as materials for solid state hydrogen storage

Energy Technology Data Exchange (ETDEWEB)

Palade, P.; Principi, G., E-mail: giovanni.principi@unipd.it; Sartori, S.; Maddalena, A. [Universita di Padova, Settore Materiali, DIM (Italy); Lo Russo, S. [Universita di Padova, Dipartimento di Fisica (Italy); Schinteie, G.; Kuncser, V.; Filoti, G. [National Institute for Materials Physics, Solid State Magnetism Department (Romania)

2006-02-15

Mg-Ni-Fe magnesium-rich intermetallic compounds were prepared following two distinct routes. A Mg{sub 88}Ni{sub 11}Fe{sub 1} sample (A) was prepared by melt spinning Mg-Ni-Fe pellets and then by high-energy ball milling for 6 h the obtained ribbons. A (MgH{sub 2}){sub 88}Ni{sub 11}Fe{sub 1} sample (B) was obtained by high-energy ball milling for 20 h a mixture of Ni, Fe and MgH{sub 2} powders in the due proportions. A SPEX8000 shaker mill with a 10:1 ball to powder ratio was used for milling in argon atmosphere. The samples were submitted to repeated hydrogen absorption/desorption cycles in a Sievert type gas-solid reaction controller at temperatures in the range 520 - 590 K and a maximum pressure of 2.5 MPa during absorption. The samples were analysed before and after the hydrogen absorption/desorption cycles by X-ray diffraction and Moessbauer spectroscopy. The results concerning the hydrogen storage properties of the studied compounds are discussed in connection with the micro-structural characteristics found by means of the used analytical techniques. The improved kinetics of hydrogen desorption for sample A, in comparison to sample B, has been ascribed to the different behaviour of iron atoms in the two cases, as proved by Moessbauer spectroscopy. In fact, iron results homogeneously distributed in sample A, partly at the Mg{sub 2}Ni grain boundaries, with catalytic effect on the gas-solid reaction; in sample B, instead, iron is dispersed inside the hydride powder as metallic iron or superparamagnetic iron.

Solid solution barium–strontium chlorides with tunable ammonia desorption properties and superior storage capacity

DEFF Research Database (Denmark)

Bialy, Agata; Jensen, Peter Bjerre; Blanchard, Didier

2015-01-01

with spray drying and in situ thermogravimetric and structural characterization, we synthesize a range of new, stable barium-strontium chloride solid solutions with superior ammonia storage densities. By tuning the barium/strontium ratio, different crystallographic phases and compositions can be obtained...... with different ammonia ab- and desorption properties. In particular it is shown, that in the molar range of 35–50% barium and 65–50% strontium, stable materials can be produced with a practically usable ammonia density (both volumetric and gravimetric) that is higher than any of the pure metal halides...

Corrosion and hydrogen absorption of commercially pure zirconium in acid fluoride solutions

International Nuclear Information System (INIS)

Yokoyama, Ken’ichi; Yamada, Daisuke; Sakai, Jun’ichi

2013-01-01

Highlights: •Zirconium corrodes and absorbs hydrogen in acid fluoride solutions. •Hydrogen thermal desorption is observed at 300–700 °C. •The resistance to hydrogen absorption of zirconium is higher than that of titanium. -- Abstract: The corrosion and hydrogen absorption of commercially pure zirconium have been investigated in acidulated phosphate fluoride (APF) solutions. Upon immersion in 2.0% APF solution of pH 5.0 at 25 °C, a granular corrosion product (Na 3 ZrF 7 ) deposits over the entire side surface of the specimen, thereby inhibiting further corrosion. In 0.2% APF solution, marked corrosion is observed from the early stage of immersion; no deposition of the corrosion product is observed by scanning electron microscopy. A substantial amount of hydrogen absorption is confirmed in both APF solutions by hydrogen thermal desorption analysis. The amount of absorbed hydrogen of the specimen immersed in the 2.0% APF solution is smaller than that in the 0.2% APF solution in the early stage of immersion. The hydrogen absorption behavior is not always consistent with the corrosion behavior. Hydrogen thermal desorption occurs in the temperature range of 300–700 °C for the specimen without the corrosion product. Under the same immersion conditions, the amount of absorbed hydrogen in commercially pure zirconium is smaller than that in commercially pure titanium as reported previously. The present results suggest that commercially pure zirconium, compared with commercially pure titanium, is highly resistant to hydrogen absorption, although corrosion occurs in fluoride solutions

Moisture Absorption/Desorption Effects on Flexural Property of Glass-Fiber-Reinforced Polyester Laminates: Three-Point Bending Test and Coupled Hygro-Mechanical Finite Element Analysis

Directory of Open Access Journals (Sweden)

Xu Jiang

2016-08-01

Full Text Available Influence of moisture absorption/desorption on the flexural properties of Glass-fibre-reinforced polymer (GFRP laminates was experimentally investigated under hot/wet aging environments. To characterize mechanical degradation, three-point bending tests were performed following the ASTM test standard (ASTM D790-10A. The flexural properties of dry (0% Mt/M∞, moisture unsaturated (30% Mt/M∞ and 50% Mt/M∞ and moisture saturated (100% Mt/M∞ specimens at both 20 and 40 °C test temperatures were compared. One cycle of moisture absorption-desorption process was considered in this study to investigate the mechanical degradation scale and the permanent damage of GFRP laminates induced by moisture diffusion. Experimental results confirm that the combination of moisture and temperature effects sincerely deteriorates the flexural properties of GFRP laminates, on both strength and stiffness. Furthermore, the reducing percentage of flexural strength is found much larger than that of E-modulus. Unrecoverable losses of E-modulus (15.0% and flexural strength (16.4% for the GFRP laminates experiencing one cycle of moisture absorption/desorption process are evident at the test temperature of 40 °C, but not for the case of 20 °C test temperature. Moreover, a coupled hygro-mechanical Finite Element (FE model was developed to characterize the mechanical behaviors of GFRP laminates at different moisture absorption/desorption stages, and the modeling method was subsequently validated with flexural test results.

Studies of the effects of TiCl{sub 3} in LiBH{sub 4}/CaH{sub 2}/TiCl{sub 3} reversible hydrogen storage system

Energy Technology Data Exchange (ETDEWEB)

Liu Dongan [Ford Motor Company, Research and Advanced Engineering, MD 1170/RIC, Dearborn, MI 48121 (United States); Department of Mechanical Engineering, University of Michigan, 1023 H. H. Dow Building 2350 Hayward Street, Ann Arbor, MI 48109-2125 (United States); Yang Jun, E-mail: jyang27@ford.com [Ford Motor Company, Research and Advanced Engineering, MD 1170/RIC, Dearborn, MI 48121 (United States); Ni Jun [Department of Mechanical Engineering, University of Michigan, 1023 H. H. Dow Building 2350 Hayward Street, Ann Arbor, MI 48109-2125 (United States); Drews, Andy [Ford Motor Company, Research and Advanced Engineering, MD 1170/RIC, Dearborn, MI 48121 (United States)

2012-02-15

lowers the hydrogen desorption temperature. In addition, the solid-liquid nano-sized phase arrangement in the nano-composites improves the hydrogen reaction kinetics. The reversible incorporation/precipitation of LiCl at the hydrogen reaction temperature and during temperature cycling makes the 6LiBH{sub 4}/CaH{sub 2}/0.25TiCl{sub 3} nano-composite a fully reversible hydrogen storage material. These four states of LiCl in LiBH{sub 4}/CaH{sub 2}/TiCl{sub 3} system, i.e. 'formed-solid solution-molten solution-precipitation', are reported for the first time and the detailed study of this system is beneficial to further improve hydrogen storage property of complex hydrides.

Hydrogenation study of suction-cast Ti{sub 40}Zr{sub 40}Ni{sub 20} quasicrystal

Energy Technology Data Exchange (ETDEWEB)

Huang, Huogen; Li, Rong; Yin, Chen; Zheng, Shaotao; Zhang, Pengcheng [National Key Laboratory for Surface Physics and Chemistry, P.O. Box 718-35, Mian Yang 621907, Sichuan (China)

2008-09-15

Suction casting was predicted to be an usable method for improving the hydriding kinetics of Ti/Zr-based icosahedral quasicrystals (IQCs) in our previous work. To further determine it, a suction-cast Ti{sub 40}Zr{sub 40}Ni{sub 20} IQC alloy was used for hydrogenation studies by Pressure Composition Isotherm (PCI) and Temperature Programmed Desorption (TPD) techniques. The results showed that, this alloy absorbed hydrogen rapidly with obvious hydrogen pressure plateau and some reversibility, however, displayed very limited hydrogen capacity (about 0.7 wt.%) and low equilibrium pressure. After several hydrogenation/dehydrogenation cycles, the IQC structure transformed into two hydride phases, ZrH{sub 2-x} and one unknown, both of which decomposed at above 600 C, suggesting high thermo-stability for them. On the whole, indeed the suction-casting method can increase the hydrogen absorption rate of Ti/Zr-based IQCs, however, the hydrogenation properties of the Ti{sub 40}Zr{sub 40}Ni{sub 20} IQC alloy still need a mighty advancement. (author)

Hydrogen storage properties in the Mg{sub 0.75}Ta{sub 0.25} system prepared by mechanical milling; Propiedades de almacenamiento de hidrogeno en el sistema Mg{sub 0.75}Ta{sub 0.25} preparado por molienda mecanica

Energy Technology Data Exchange (ETDEWEB)

Ramirez G, J. A.

2016-07-01

Magnesium and most of its mixtures have slow sorption-desorption kinetics of hydrogen, which limits their technological application and their viability from the economic view point. Recently, has been observed that by the synthesis of advanced materials, using the mechanical milling technique, positive changes in the kinetics are introduced. In order to improve the sorption-desorption hydrogen properties, in the present work a mixture consisting of Mg{sub 0.75}Ta{sub 0.25} was prepared using methanol as process control agent. To this end, the first methodological step was to carry out, by means of the mechanical milling technique, the synthesis of the mixture Mg{sub 0.75}Ta{sub 0.25} in a Spex type vibratory mill at times of 6, 12, 18 and 24 h. Subsequently, the material was characterized by different analytical techniques such as scanning electron microscopy with elemental analysis, X-ray diffraction and N{sub 2} physisorption analysis. Subsequently, hydrogen sorption experiments were carried out in a Parr reactor to evaluate the hydrogen storage capacity of the mixture, varying temperature parameters, pressure and time, in order to determine the optimal parameters of hydrogen sorption. The characterization of the hydrogen storage capacity was analyzed by the thermogravimetric analysis/differential scanning calorimetry technique coupled to a mass spectrometer. X ray diffraction analysis reveals that there is a mixture between the starting compounds, with an important refinement of the microstructure as a consequence of the mechanical milling process. The results of the hydrogen sorption tests at 1, 5 and 10 cycles showed that the storage of hydrogen in the Mg{sub 0.75}Ta{sub 0.25} mixture can be carried out at a temperature of 25 degrees Celsius with a pressure of 2 atm and a contact time of 1 h. (Author)

Recent progress of hydrogen isotope behavior studies for neutron or heavy ion damaged W

International Nuclear Information System (INIS)

Oya, Yasuhisa; Hatano, Yuji; Shimada, Masashi; Buchenauer, Dean; Kolasinski, Robert; Merrill, Brad; Kondo, Sosuke; Hinoki, Tatsuya; Alimov, Vladimir Kh.

2016-01-01

Highlights: • This paper reviews recent results pertaining to hydrogen isotope behavior in neutron and heavy ion damaged W. • Accumulation of damage in W creates stable trapping sites for hydrogen isotopes, thereby changing the observed desorption behavior. • The distribution of defects throughout the sample also changes the shape of TDS spectrum. • Experimental results show that production of Re by nuclear reaction of W with neutrons reduces the density of trapping sites, though no remarkable retention enhancement is observed. - Abstract: This paper reviews recent results pertaining to hydrogen isotope behavior in neutron and heavy ion damaged W. Accumulation of damage in W creates stable trapping sites for hydrogen isotopes, thereby changing the observed desorption behavior. In particular, the desorption temperature shifts higher as the defect concentration increases. In addition, the distribution of defects throughout the sample also changes the shape of TDS spectrum. Even if low energy traps were distributed in the bulk region, the D diffusion toward the surface requires additional time for trapping/detrapping during surface-to-bulk transport, contributing to a shift of desorption peaks toward higher temperatures. It can be said that both of distribution of damage (e.g. hydrogen isotope trapping sites) and their stabilities would have a large impact on desorption. In addition, transmutation effects should be also considered for an actual fusion environment. Experimental results show that production of Re by nuclear reaction of W with neutrons reduces the density of trapping sites, though no remarkable retention enhancement is observed.

Recent progress of hydrogen isotope behavior studies for neutron or heavy ion damaged W

Energy Technology Data Exchange (ETDEWEB)

Oya, Yasuhisa, E-mail: syoya@ipc.shizuoka.ac.jp [Shizuoka University, 836 Ohya, Suruga-ku Shizuoka 422-8529 (Japan); Hatano, Yuji [University of Toyama, 3190 Gofuku, Toyama 939-8555 (Japan); Shimada, Masashi [Idaho National Laboratory, Idaho Falls, ID 83415 (United States); Buchenauer, Dean; Kolasinski, Robert [Sandia National Laboratories, Livermore, CA 94551 (United States); Merrill, Brad [Idaho National Laboratory, Idaho Falls, ID 83415 (United States); Kondo, Sosuke; Hinoki, Tatsuya [Kyoto University, Gokasho, Uji 611-0011 (Japan); Alimov, Vladimir Kh. [University of Toyama, 3190 Gofuku, Toyama 939-8555 (Japan)

2016-12-15

Highlights: • This paper reviews recent results pertaining to hydrogen isotope behavior in neutron and heavy ion damaged W. • Accumulation of damage in W creates stable trapping sites for hydrogen isotopes, thereby changing the observed desorption behavior. • The distribution of defects throughout the sample also changes the shape of TDS spectrum. • Experimental results show that production of Re by nuclear reaction of W with neutrons reduces the density of trapping sites, though no remarkable retention enhancement is observed. - Abstract: This paper reviews recent results pertaining to hydrogen isotope behavior in neutron and heavy ion damaged W. Accumulation of damage in W creates stable trapping sites for hydrogen isotopes, thereby changing the observed desorption behavior. In particular, the desorption temperature shifts higher as the defect concentration increases. In addition, the distribution of defects throughout the sample also changes the shape of TDS spectrum. Even if low energy traps were distributed in the bulk region, the D diffusion toward the surface requires additional time for trapping/detrapping during surface-to-bulk transport, contributing to a shift of desorption peaks toward higher temperatures. It can be said that both of distribution of damage (e.g. hydrogen isotope trapping sites) and their stabilities would have a large impact on desorption. In addition, transmutation effects should be also considered for an actual fusion environment. Experimental results show that production of Re by nuclear reaction of W with neutrons reduces the density of trapping sites, though no remarkable retention enhancement is observed.

Influence of Surface Charge/Potential of a Gold Electrode on the Adsorptive/Desorptive Behaviour of Fibrinogen

International Nuclear Information System (INIS)

Dargahi, Mahdi; Konkov, Evgeny; Omanovic, Sasha

2015-01-01

Highlights: • Adsorptive/desorptive behavior of fibrinogen (FG) on an electrochemically-polarized gold substrate is reported. • The adsorption affinity of FG (afFG) is constant on a negatively-charged substrate surface. • The afFG increases linearly with an increase in positive substrate surface charge. • The FG adsorption kinetics is strongly dependant on substrate surface charge. • The adsorbed FG layer can be desorbed by electrochemical evolution of hydrogen and oxygen. - Abstract: The effect of gold substrate surface charge (potential) on adsorptive/desorptive behaviour of fibrinogen (FG) was studied by employing differential capacitance (DC) and polarization modulated infrared reflection absorption spectroscopy (PM-IRRAS), in terms of FG adsorption thermodynamics, kinetics, and desorption kinetics. The gold substrate surface charge was modulated in-situ within the electrochemical double-layer region by means of electrochemical potentiostatic polarization in a FG-containing electrolyte, thus avoiding the interference of other physico-chemical properties of the gold surface on FG’s interfacial behaviour. The FG adsorption equilibrium was modeled using the Langmuir isotherm. Highly negative values of apparent Gibbs free energy of adsorption (ranging from from −52.1 ± 0.4 to −55.8 ± 0.8 kJ mol −1 , depending on the FG adsorption potential) indicated a highly spontaneous and strong adsorption of FG onto the gold surface. The apparent Gibbs free energy of adsorption was found to be independent of surface charge when the surface was negatively charged. However, when the gold surface was positively charged, the apparent Gibbs free energy of adsorption exhibited a pronounced linear relationship with the surface charge, shifting to more negative values with an increase in positive electrode potential. The adsorption kinetics of FG was also found to be dependent on gold surface charge in a similar manner to the apparent Gibbs free energy of adsorption

Influence of adsorbed carbon dioxide on hydrogen electrosorption in palladium-platinum-rhodium alloys

International Nuclear Information System (INIS)

Lukaszewski, M.; Grden, M.; Czerwinski, A.

2004-01-01

Carbon dioxide electroreduction was applied to examine the processes of hydrogen electrosorption (adsorption, absorption and desorption) by thin electrodeposits of Pd-Pt-Rh alloys under conditions of cyclic voltammetric (CV) experiments. Due to different adsorption characteristics towards the adsorption product of the electroreduction of CO 2 (reduced CO 2 ) exhibited by the alloy components hydrogen adsorption and hydrogen absorption signals can be distinguished on CV curves. Reduced CO 2 causes partial blocking of hydrogen adsorbed on surface Pt and Rh atoms, without any significant effect on hydrogen absorption into alloy. It reflects the fact that adsorbed hydrogen bonded to Pd atoms does not participate in CO 2 reduction, while hydrogen adsorbed on Pt and Rh surface sites is inactive in the absorption reaction. In contrast, CO is adsorbed on all alloy components and causes a marked inhibition of hydrogen sorption (both adsorption and absorption)/desorption reactions

Thermoanalytical investigation of the hydrogen absorption behaviour of Sm{sub 2}Fe{sub 17-x}Ga{sub x} at high hydrogen pressures

Energy Technology Data Exchange (ETDEWEB)

Handstein, A.; Kubis, M.; Gebel, B.; Mueller, K.-H.; Schultz, L. [Institut fuer Festkoerper- und Werkstofforschung Dresden e.V. (Germany). Inst. fuer Metallische Werkstoffe; Gutfleisch, O.; Harris, I.R. [Institut fuer Festkoerper- und Werkstofforschung Dresden e.V. (Germany). Inst. fuer Metallische Werkstoffe]|[Birmingham Univ. (United Kingdom). School of Metallurgy and Materials

1998-07-01

The complete disproportionation of Sm{sub 2}Fe{sub 17-x}Ga{sub x} during annealing in hydrogen is hindered due to an increased stability of the compounds with a higher Ga content (x {>=} 1). Therefore the HD process as the first step of HDDR (hydrogenation-disproportionation-desorption-recombination) has to be carried out at a high hydrogen pressure for x {>=} 1. The hydrogen absorption behaviour of Sm{sub 2}Fe{sub 17-x}Ga{sub x} (x = 0, 0.5, 1 and 2) was investigated by means of hydrogen differential thermal analysis (HDTA) and high pressure differential scanning calorimetry (HPDSC) at hydrogen pressures up to 70 bar. A dependency of hydrogenation and disproportionation temperatures on hydrogen pressure and Ga content was found. The comparison with other substituents (M = Al and Si) instead of M = Ga showed an increased stability of Sm{sub 2}Fe{sub 17-x}M{sub x} compounds against disproportionation by hydrogen in the sequence Al, Ga and Si. The Curie temperatures of the interstitially hydrogenated Th{sub 2}Zn{sub 17}-type materials increase with the hydrogen pressure. In order to produce coercive and thermally stable Sm{sub 2}Fe{sub 15}Ga{sub 2}C{sub y} powder by means of the HDDR process, we recombined material disproportionated at different hydrogen pressures. Preliminary results of magnetic properties of this HDDR treated and gas-carburized Sm{sub 2}Fe{sub 15}Ga{sub 2}C{sub y} are discussed. (orig.)

Gas-phase hydrogenation of benzene on supported nickel catalyst

Energy Technology Data Exchange (ETDEWEB)

Franco, H.A.; Phillips, M.J.

1980-06-01

The reaction of 22.66-280 Pa benzene with 72.39-122.79 Pa hydrogen on kieselguhr-supported nickel at 392.2/sup 0/-468.2/sup 0/K yielded only cyclohexane and was independent of 5.33-40 Pa cyclohexane added to the feed of the differential flow reactor. Best fit for the kinetic data was obtained with a rate equation developed by van Meerten and Coenen which assumed that all hydrogen addition steps have the same rate constant and are slow. An observed rate maximum at 458/sup 0/K may be the result of an increasing rate constant and decreasing cyclohexyl surface coverage as the temperature increases. Temperature-programed hydrogen desorption showed a series of desorption peaks at 358/sup 0/-600/sup 0/K, including one at 453/sup 0/K, which may be due to the hydrogen involved in the surface reaction.

Determination of diffusible and total hydrogen concentration in coated and uncoated steel

Energy Technology Data Exchange (ETDEWEB)

Mabho, Nonhlangabezo

2010-09-23

The new trend in the steel industry demands thin, flexible, high strength steels with low internal embrittlement. It is a well known fact that the atomic hydrogen which is picked up during production, fabrication and service embrittles the steel. This has led to an extensive research towards the improvement of the quality of metallic materials by focusing on total and diffusible hydrogen concentrations which are responsible for hydrogen embrittlement. Since the internal embrittlement cannot be foreseen, the concentrations of diffusible hydrogen work as indicators while the total hydrogen characterizes the absorbed quantities and quality of that particular product. To meet these requirements, the analytical chemistry methods which include the already existing carrier gas melt (fusion) extraction methods that use infrared and thermal conductivity for total hydrogen detection were applied. The newly constructed carrier gas thermal desorption mass spectroscopy was applied to monitor the diffusible concentration at specific temperatures and desorption rates of hydrogen which will contribute towards the quality of materials during service. The TDMS method also involved the characterization of the energy quantity (activation energy) required by hydrogen to be removed from traps of which irreversible traps are preferred because they enhance the stability of the product by inhibiting the mobility of hydrogen which is detrimental to the metallic structures. The instrumentation for TDMS is quite simple, compact, costs less and applicable to routine analysis. To determine total and diffusible hydrogen, the influence of the following processes: chemical and mechanical zinc coating removal, sample cleaning with organic solvents, conditions for hydrogen absorption by electrolytic hydrogen charging, conditions of hydrogen desorption by storing the sample at room temperature, solid CO{sub 2} and at temperatures of the drier was analysed. The contribution of steel alloys towards

Comparison of hydrogen storage properties of pure Mg and milled ...

Indian Academy of Sciences (India)

Administrator

increase the hydriding and dehydriding rates, pure Mg was ground under hydrogen atmosphere (reactive .... Hydrogen storage properties of pure Mg and milled pure Mg. 833. Figure 3. ... elongated and flat shapes via collisions with the steel.

Sorption and desorption of diuron in Oxisol under biochar application

Directory of Open Access Journals (Sweden)

Fabiano André Petter

Full Text Available ABSTRACT The objective of this study was to verify the kinetics of sorption and desorption of diuron in an Oxisol under application of biochar. The samples were collected in a field experiment conducted in randomized design blocks consisted of 2 base fertilization levels (0 and 400 kg∙ha−1 NPK 00-20-20 fertilizer formula and 3 doses of biochar (0, 8 and 16 Mg∙ha−1. In the evaluation of sorption and desorption, Batch Equilibrium method was used. The kinetics of sorption and desorption of diuron, total organic carbon, fulvic acid, humic acid and humin, pH and partition coefficient to organic carbon were evaluated. The Freundlich isotherm was adjusted appropriately to describe diuron sorption kinetics in all the studied treatments. The application of biochar provided increment in the sorption (Kf and reduction in the desorption of diuron in 64 and 44%, respectively. This effect is attributed to the biochar contribution to the total organic carbon and C-humin and of these to diuron through hydrophobic interactions and hydrogen bonds. The positive correlation between the partition coefficient to organic carbon and Kf confirms the importance of soil organic compartment in the sorption of diuron. There was no competition of NPK fertilizer for the same sorption site of diuron. The increase and reduction in sorption and desorption, respectively, show that the application of biochar is an important alternative for the remediation of soil leaching of diuron, especially in sandy soils.

Realizing nanographene activated by a vacancy to solve hydrogen storage problem

Science.gov (United States)

Sunnardianto, Gagus Ketut; Maruyama, Isao; Kusakabe, Koichi

We found a triply hydrogenated vacancy (V111) in nanographene reduces an activation barrier of adsorption-desorption process in both ways in an equal manner from the known values for pristine graphene as well as those of other hydrogenated vacancies of graphene. This finding may give a key to overcome existing problems in the hydrogen uptake and release processes in known hydrogen storage materials, e.g. graphene and organic hydrides (OHs) in near ambient operation temperature. In this study, we used DFT-NEB simulation to estimate the barrier height, which is supported by realized real experiments. We consider a nanographene molecule (VANG) which contains V111 with armchair structure at the periphery. We found interesting feature in comparable values of energy barriers for both hydrogen uptake and release, where hydrogenation process is even a little bit endothermic and dehydrogenation is a little but exothermic nature. Thus, this material structure acts as ``self-catalytic properties'', which has an important role in reducing an energy barrier and as a trapping site for hydrogen serving a new material prevailing other hopeful candidates. The work is supported by JSPS KAKENHI in Science of Atomic Layers\\x9D.

Data compilation for radiation effects on hydrogen recycle in fusion reactor materials

International Nuclear Information System (INIS)

Ozawa, Kunio; Fukushima, Kimichika; Ebisawa, Katsuyuki.

1984-05-01

Irradiation tests of materials by hydrogen isotopes are under way, to investigate the hydrogen recycling process where exchange of fuel particles takes place between plasma and the wall of the nuclear fusion reactor. In the report, data on hydrogen irradiation are collected and reviewed from the view point of irradiation effects. Data are classified into, (1) Re-emmission, (2) Retention, (Retained hydrogen isotopes, Depth profile in the materials and Thermal desorption spectroscopy), (3) Permeation and (4) Ion impact desorption. Research activities in each area are arranged according to the date of publication, research institutes, materials investigated, so that overview of present status can be made. Then, institute, author and reference are shown for each classification with tables. The list of literature is also attached. (author)

Modeling of the thermal effects of hydrogen adsorption on activated carbon

International Nuclear Information System (INIS)

Richard, M.-A.; Chahine, R.

2006-01-01

'Full text:' Heat management is one of the most critical issues for the design of efficient adsorption-based storage of hydrogen. We present simulations of mass and energy balance for hydrogen and nitrogen adsorption on activated carbon over wide temperature and pressure ranges. First, the Dubinin-Astakhov (DA) model is adapted to model excess hydrogen and nitrogen adsorption isotherms at high pressures and supercritical temperatures assuming a constant microporous adsorption volume. The five parameter modified D-A adsorption model is shown to fit the experimental data over the temperature range (35 K-293 K) for hydrogen and (93 K-298 K) for nitrogen and pressure range (0-6 MPa) within the experimental uncertainties of the measurement system. We derive the thermodynamic properties of the adsorbed phase from this analytical expression of the measured data. The mass and energy rate balance equations in a microporous adsorbent/adsorbate system are then presented and validated with nitrogen desorption experiments. Finally, simulations of adiabatic and isothermal filling of adsorption-based hydrogen storage are presented and discussed. (author)

Estimation of Physical Properties for Hydrogen Isotopes Using Aspen Plus Simulator

International Nuclear Information System (INIS)

Cho, Jung Ho; Yun, Sei Hun; Cho, Seung Yon; Chang, Min Ho; Kang, Hyun Goo; Jung, Ki Jung; Kim, Dong Min

2009-01-01

Hydrogen isotopes are H 2 , HD, D 2 , H 2 , HD, D 2 , HT, DT and T 2 . Among the hydrogen isotopes, the physical properties of H2, HD and D+2 are included in the Aspen Plus, however HT, D T and T 2 are not included. In this study, various thermodynamic properties were estimated for six components of isotopes by use of the fixed properties and temperature-dependent properties. To estimate thermodynamic properties, Soave modified Redlich-Kwong equation of state and Aspenplus simulator was used. The results were verified and compared with by PRO/II with PROVISION of Invensys

Effect of hydrogen on stresses in anodic oxide film on titanium

International Nuclear Information System (INIS)

Kim, Joong-Do; Pyun, Su-Il; Seo, Masahiro

2003-01-01

Stresses in anodic oxide film on titanium thin film/glass electrode in pH 8.4 borate solution were investigated by a bending beam method. The increases in compressive stress observed with cathodic potential sweeps after formation of anodic oxide film were attributed to the volume expansion due to the compositional change of anodic oxide film from TiO 2 to TiO 2-x (OH) x . The instantaneous responses of changes in stress, Δσ, in the anodic oxide film to potential steps demonstrated the reversible characteristic of the TiO 2-x (OH) x formation reaction. In contrast, the transient feature of Δσ for the titanium without anodic oxide film represented the irreversible formation of TiH x at the metal/oxide interphase. The large difference in stress between with and without the oxide film, has suggested that most of stresses generated during the hydrogen absorption/desorption reside in the anodic oxide film. A linear relationship between changes in stress, Δ(Δσ) des , and electric charge, ΔQ des , during hydrogen desorption was found from the current and stress transients, manifesting that the stress changes were crucially determined by the amount of hydrogen desorbed from the oxide film. The increasing tendency of -Δ(Δσ) des with increasing number of potential steps and film formation potential were discussed in connection with the increase in desorption amount of hydrogen in the oxide film with increasing absorption/desorption cycles and oxide film thickness

A comparison of hydrogen vs. helium glow discharge effects on fusion device first-wall conditioning

International Nuclear Information System (INIS)

Dylla, H.F.

1989-09-01

Hydrogen- and deuterium-fueled glow discharges are used for the initial conditioning of magnetic fusion device vacuum vessels following evacuation from atmospheric pressure. Hydrogenic glow discharge conditioning (GDC) significantly reduces the near-surface concentration of simple adsorbates, such as H 2 O, CO, and CH 4 , and lowers ion-induced desorption coefficients by typically three orders of magnitude. The time evolution of the residual gas production observed during hydrogen-glow discharge conditioning of the carbon first-wall structure of the TFTR device is similar to the time evolution observed during hydrogen GDC of the initial first-wall configuration in TFTR, which was primarily stainless steel. Recently, helium GDC has been investigated for several wall-conditioning tasks on a number of tokamaks including TFTR. Helium GDC shows negligible impurity removal with stainless steel walls. For impurity conditioning with carbon walls, helium GDC shows significant desorption of H 2 O, CO, and CO 2 ; however, the total desorption yield is limited to the monolayer range. In addition, helium GDC can be used to displace hydrogen isotopes from the near-surface region of carbon first-walls in order to lower hydrogenic retention and recycling. 38 refs., 6 figs

Adsorption and desorption properties of TiZrV getter film at different temperatures in the presence of synchrotron radiation

CERN Document Server

Anashin, V V; Krasnov, A A; Ruzinov, V L

2008-01-01

The coating of vacuum chambers with TiZrV non-evaporable getter (NEG) developed at CERN is an attractive pumping technology for vacuum systems. Once activated the NEG coating is a material since apart from providing distributed pumping, it may inhibit the gas desorption from the vast reservoir of the industrially prepared substrate material. The present work includes an advanced study of NEG properties under Synchrotron Radiation (SR) at temperatures in the range from 300K to 90K. The work was performed at BINP using SR from the VEPP-3 storage ring. The main result is that dynamic pressure and desorption of H2 inside NEG coated chamber at 90K are significantly less than those at room temperature.

Improved correlations of hydrogen content versus combustion performance related properties of aviation turbine fuels

Energy Technology Data Exchange (ETDEWEB)

Nagpal, J.M.; Sharma, R.L.; Sagu, M.L.; Tiwari, G.B. (Indian Institute of Petroleum, Dehradun (India))

1994-01-01

In recent years the hydrogen content of Aviation Fuels has generated considerable interest. Various investigators have suggested correlation of hydrogen content with combustion related properties of aviation turbine fuel (ATF). A suitable threshold value of hydrogen content 13.8 wt% is being considered as a waiver of specifications such as specific energy, aniline gravity product, smoke point, aromatic content, naphthalenes and luminometer number. In the present paper relationship between the hydrogen content and combustion related properties has been examined and improved correlations of hydrogen content with several combustion related properties have been developed by incorporating a characterization factor in the equations. The supporting threshold value of a hydrogen content of 13.8wt% is verified with 25 data points for waiving of combustion properties such as specific energy, aniline gravity product, smoke point and aromatic content from aviation turbine fuel. 6 refs., 12 figs., 2 tabs.

Hydrogenation Properties of Mg-5 wt.% TiCr_10NbX (x=1,3,5) Composites by Mechanical Alloying Process

International Nuclear Information System (INIS)

Kim, Kyeong-Il; Hong, Tae-Whan

2011-01-01

Hydrogen and hydrogen energy have been recognized as clean energy sources and high energy carrier. Mg and Mg alloys are attractive hydrogen storage materials because of their lightweight and low cost materials with high hydrogen capacity (about 7.6 wt.%). However, the commercial applications of the Mg hydrides are currently hinder by its high absorption/desorption temperature, and very slow reaction kinetics. However, Ti and Ti based hydrogen storage alloys have been thought to be the third generation of alloys with a high hydrogen capacity, which makes it difficult to handle because of high reactivity. One of the most methods to develop kinetics was addition of transition metal. Therefore, Mg-Ti-Cr-Nb alloy was fabricated to add TiCrNb by hydrogen induced mechanical alloying. TiCrNb systems have included transition metals, low operating temperatures and hydrogen storage materials. As-received specimens were characterized using X-ray Diffraction analysis (XRD), Scanning Electron Microscopy (SEM) and Thermo Gravimetric analysis/Differential Scanning Calorimetry (TG/DSC). Mg-TiCr_10Nb systems were evaluated for hydrogen kinetics by Sievert’s type Pressure-Composition-Isotherm (PCI) equipment. The operating temperature range was 473, 523, 573 and 623 K.

Ageing of Mg-Ni-H hydrogen storage alloys

Czech Academy of Sciences Publication Activity Database

Čermák, Jiří; Král, Lubomír

2012-01-01

Roč. 37, OCT (2012), s. 14257-14264 ISSN 0360-3199 R&D Projects: GA MŠk(CZ) ED1.1.00/02.0068; GA ČR GA106/09/0814; GA ČR(CZ) GAP108/11/0148 Institutional research plan: CEZ:AV0Z20410507 Keywords : Magnesium alloys * Hydrogen desorption * Hydrogen storage * Hydrogen-storage materials * Ageing Subject RIV: JG - Metallurgy Impact factor: 3.548, year: 2012

A micro-fabricated hydrogen storage module with sub-atmospheric activation and durability in air exposure

Energy Technology Data Exchange (ETDEWEB)

Shan, Xi; Payer, Joe H. [Corrosion and Reliability Engineering, Department of Chemical and Biomolecular Engineering, University of Akron, 302 Buchtel Common, Akron, OH 44325 (United States); Wainright, Jesse S.; Dudik, Laurie [Department of Chemical Engineering, Case Western Reserve University, Cleveland, OH 44106 (United States)

2011-01-15

The objective of this work was to develop a hydrogen storage module for onboard electrical power sources suitable for use in micro-power systems and micro-electro-mechanical systems (MEMS). Hydrogen storage materials were developed as thin-film inks to be compatible with an integrated manufacturing process. Important design aspects were (a) ready activation at sub-atmospheric hydrogen pressure and room temperature and (b) durability, i.e. capable of hundreds of absorption/desorption cycles and resistance to deactivation on exposure to air. Inks with palladium-treated intermetallic hydrogen storage alloys were developed and are shown here to be compatible with a thin-film micro-fabrication process. These hydrogen storage modules absorb hydrogen readily at atmospheric pressure, and the absorption/desorption rates remained fast even after the ink was exposed to air for 47 weeks. (author)

A biosensor for hydrogen peroxide detection based on electronic properties of carbon nanotubes

Science.gov (United States)

Majidi, Roya

2013-01-01

Density functional theory has been used to study the effect of hydrogen peroxide on the electronic properties of single walled carbon nanotubes. The metallic and semiconducting carbon nanotubes have been considered in the presence of different number of hydrogen peroxide. The results indicate that hydrogen peroxide has no significant effect on the metallic nanotube and these nanotubes remain to be metallic. In contrast, the electronic properties of the semiconducting nanotubes are so sensitive to hydrogen peroxide. The energy band gap of these nanotubes is decreased by increasing the number of hydrogen peroxide. The electronic sensivity of the carbon nanotubes to hydrogen peroxide opens new insights into developing biosensors based on the single walled carbon nanotubes.

Hydrogenation of carbon monoxide over supported palladium catalysts

Energy Technology Data Exchange (ETDEWEB)

Fujimoto, K.; Hashimoto, H.; Kunugi, T.

1978-03-01

An alumina-supported 2% palladium catalyst had higher activity for carbon monoxide hydrogenation than a silica-supported 2% palladium catalyst, at 250/sup 0/-400/sup 0/C and 1 atm. The addition of lanthanum oxide or thorium oxide, but not of potassium oxide, to the silica-supported catalyst increased the conversion at 350/sup 0/C from 1.1% to 81.0% with a selectivity of 56.1% for methane, 1.4% for C/sub 2/ compounds, 0.1% for C/sub 3/ compounds, and 42.5% for carbon dioxide. Temperature-programed desorption of carbon monoxide in a hydrogen stream showed that of two desorption peaks observed for carbon monoxide, the one at higher temperature corresponded to the carbon monoxide species which hydrogenates to methane and that the area of this peak increased with increasing thorium content of the catalyst. Graphs, tables, and 12 references.

Improving of understanding of beta-hexachlorocyclohexane (HCH) adsorption on activated carbons by temperature-programmed desorption studies.

Science.gov (United States)

Passé-Coutrin, Nady; Maisonneuve, Laetitia; Durimel, Axelle; Dentzer, Joseph; Gadiou, Roger; Gaspard, Sarra

2016-01-01

In order to understand the interactions between beta-hexachlorocyclohexane (HCH) and chemical groups at activated carbon (AC) surface, the solid samples were hydrogenated aiming to decrease the amounts of oxygenated groups. Two AC samples designated by BagH2O and BagP1.5 were prepared by water vapor activation and phosphoric acid activation, respectively, of sugarcane bagasse used as an AC precursor. A more simple molecule 1,2,3-trichloropropane (TCP) is used as a model of chlorinated compound. The AC were characterized by infrared, X-ray photoelectron spectroscopy (XPS), Raman resonance spectroscopies, as well as temperature-programmed desorption coupled with mass spectrometry (TPD-MS). BagP1.5 and BagH2O AC surface contained oxygenated groups. Upon hydrogenation, a decrease of most of these group amxounts was observed for both samples, while hydroxyl groups increased. On the basis of temperature-programmed desorption data obtained for AC samples contaminated with TCP or HCH, it was possible to determine the type of hydrogen bond formed between each AC and HCH.

Film growth, adsorption and desorption kinetics of indigo on SiO{sub 2}

Energy Technology Data Exchange (ETDEWEB)

Scherwitzl, Boris, E-mail: b.scherwitzl@tugraz.at; Resel, Roland; Winkler, Adolf [Institute of Solid State Physics, Graz University of Technology, Petersgasse 16, A-8010 Graz (Austria)

2014-05-14

Organic dyes have recently been discovered as promising semiconducting materials, attributable to the formation of hydrogen bonds. In this work, the adsorption and desorption behavior, as well as thin film growth was studied in detail for indigo molecules on silicon dioxide with different substrate treatments. The material was evaporated onto the substrate by means of physical vapor deposition under ultra-high vacuum conditions and was subsequently studied by Thermal Desorption Spectroscopy (TDS), Auger Electron Spectroscopy, X-Ray Diffraction, and Atomic Force Microscopy. TDS revealed initially adsorbed molecules to be strongly bonded on a sputter cleaned surface. After further deposition a formation of dimers is suggested, which de-stabilizes the bonding mechanism to the substrate and leads to a weakly bonded adsorbate. The dimers are highly mobile on the surface until they get incorporated into energetically favourable three-dimensional islands in a dewetting process. The stronger bonding of molecules within those islands could be shown by a higher desorption temperature. On a carbon contaminated surface no strongly bonded molecules appeared initially, weakly bonded monomers rather rearrange into islands at a surface coverage that is equivalent to one third of a monolayer of flat-lying molecules. The sticking coefficient was found to be unity on both substrates. The desorption energies from carbon covered silicon dioxide calculated to 1.67 ± 0.05 eV for multilayer desorption from the islands and 0.84 ± 0.05 eV for monolayer desorption. Corresponding values for desorption from a sputter cleaned surface are 1.53 ± 0.05 eV for multilayer and 0.83 ± 0.05 eV for monolayer desorption.

ECO LOGIC INTERNATIONAL GAS-PHASE CHEMICAL REDUCTION PROCESS - THE THERMAL DESORPTION UNIT - APPLICATIONS ANALYSIS REPORT

Science.gov (United States)

ELI ECO Logic International, Inc.'s Thermal Desorption Unit (TDU) is specifically designed for use with Eco Logic's Gas Phase Chemical Reduction Process. The technology uses an externally heated bath of molten tin in a hydrogen atmosphere to desorb hazardous organic compounds fro...

Effects of hydrogen-charging on the properties of S235JR steel

Science.gov (United States)

Pietkun-Greber, Izabela

2017-10-01

The paper presents the test results of the S235JR steel susceptibility to damage under the influence of hydrogen. The test of mechanical properties was performed on the basis of a static stretch test of non-hydrogenated samples and after cathodic polarization. Electrochemical measurements for the assessment of corrosion resistance of non-hydrogenated and hydrogenated steels were carried out using open circuit potential measurement and registering of potentiodynamic polarization curves in a three-electrode measuring system. Hydrogenation was carried out for between 3 and 24 hours in a solution of 0.1 N sulfuric acid (VI) with the addition of 2 mg/dm 3 of arsenic oxide (III) at an electric current density of 10 mA/cm2. The hydrogen content in the steel before and after saturation with hydrogen was determined using the analyzer. Fracture samples after tensile test were observed using scanning electron microscope. The results of the research showed that as the hydrogen concentration in the examined steel increased (the lengthening of the saturation time), the deterioration of its mechanical and electrochemical properties occurred.

Hydrogen storage in Mg-Ni-Fe compounds prepared by melt spinning and ball milling

Energy Technology Data Exchange (ETDEWEB)

Palade, P. [Settore Materiali, Dipartimento di Ingegneria Meccanica, Universita di Padova, via Marzolo 9, 35131 Padova (Italy); National Institute for Physics of Materials, Atomistilor 105 bis, P.O. Box MG-7, 077125 Bucharest-Magurele (Romania); Sartori, S. [Settore Materiali, Dipartimento di Ingegneria Meccanica, Universita di Padova, via Marzolo 9, 35131 Padova (Italy); Maddalena, A. [Settore Materiali, Dipartimento di Ingegneria Meccanica, Universita di Padova, via Marzolo 9, 35131 Padova (Italy); Principi, G. [Settore Materiali, Dipartimento di Ingegneria Meccanica, Universita di Padova, via Marzolo 9, 35131 Padova (Italy)]. E-mail: giovanni.principi@unipd.it; Lo Russo, S. [Dipartimento di Fisica, Universita di Padova, Via Marzolo 8, 35131 Padova (Italy); Lazarescu, M. [National Institute for Physics of Materials, Atomistilor 105 bis, P.O. Box MG-7, 077125 Bucharest-Magurele (Romania); Schinteie, G. [National Institute for Physics of Materials, Atomistilor 105 bis, P.O. Box MG-7, 077125 Bucharest-Magurele (Romania); Kuncser, V. [National Institute for Physics of Materials, Atomistilor 105 bis, P.O. Box MG-7, 077125 Bucharest-Magurele (Romania); Filoti, G. [National Institute for Physics of Materials, Atomistilor 105 bis, P.O. Box MG-7, 077125 Bucharest-Magurele (Romania)

2006-05-18

Magnesium-rich Mg-Ni-Fe intermetallic compounds have been prepared by two different routes: (a) short time ball milling of ribbons obtained by melt spinning; (b) long time ball milling of a mixture of MgH{sub 2}, Ni and Fe powders. The first type of samples displays an hydrogen desorption kinetics better than the second one. Pressure composition isotherm measurements exhibit for both type of samples two plateaux, the lower and wider corresponding to the MgH{sub 2} phase and the upper and shorter corresponding to the Mg{sub 2}NiH{sub 4} phase. The presence of the two types of hydrides is confirmed by X-ray diffraction analysis. Moessbauer spectroscopy shows that in melt spun and subsequently milled samples iron is mainly in a disordered structure and segregates after hydrogenation, while in directly milled powders remains mainly unalloyed. After multiple hydrogen absorption/desorption cycles the main part of iron is in metallic state in samples of both types, those of first type preserving better hydrogen desorption kinetics.

Zirconium-nickel crystals—hydrogen accumulators: Dissolution and penetration of hydrogen atoms in alloys

Science.gov (United States)

Matysina, Z. A.; Zaginaichenko, S. Yu.; Shchur, D. V.; Gabdullin, M. T.; Kamenetskaya, E. A.

2016-07-01

The calculation of the free energy, thermodynamic equilibrium equations, and kinetic equations of the intermetallic compound Zr2NiH x has been carried out based on molecular-kinetic concepts. The equilibrium hydrogen concentration depending on the temperature, pressure, and energy parameters has been calculated. The absorption-desorption of hydrogen has been studied, and the possibility of the realization of the hysteresis effect has been revealed. The kinetics of the dissolution and permeability of hydrogen is considered, the time dependence of these values has been found, and conditions for the extremum character of their time dependence have been determined. Relaxation times of the dissolution and permeability of hydrogen into the alloy have been calculated. The calculation results are compared with the experimental data available in the literature.

Microstructural evolution during hydrogen sorption cycling of Mg-FeTi nanolayered composites

Energy Technology Data Exchange (ETDEWEB)

Kalisvaart, W.P., E-mail: pkalisvaart@gmail.com [Chemical and Materials Engineering, University of Alberta and National Research Council Canada, National Institute for Nanotechnology, Edmonton, AB, T6G 2V4 (Canada); Kubis, Alan; Danaie, Mohsen; Amirkhiz, Babak Shalchi [Chemical and Materials Engineering, University of Alberta and National Research Council Canada, National Institute for Nanotechnology, Edmonton, AB, T6G 2V4 (Canada); Mitlin, David, E-mail: dmitlin@ualberta.ca [Chemical and Materials Engineering, University of Alberta and National Research Council Canada, National Institute for Nanotechnology, Edmonton, AB, T6G 2V4 (Canada)

2011-03-15

This paper describes the microstructural evolution of Mg-FeTi mutlilayered hydrogen storage materials during extended cycling. A 28 nm Mg-5 nm FeTi multilayer has comparable performance to a cosputtered material with an equivalent composition (Mg-10%Fe-10%Ti), which is included as a baseline case. At 200 deg. C, the FeTi layers act as a barrier, preventing agglomeration of Mg particles. At 300 deg. C, the initial structure of the multilayer is preserved up to 35 cycles, followed by fracturing of the Mg layers in the in-plane direction and progressive delamination of the FeTi layers as observed by electron microscopy. Concurrently, an increase in the Mg grain size was observed from 32 to 76 nm between cycles 35 and 300. As a result, the absorption kinetics deteriorate with cycling, although 90% of the total capacity is still absorbed within 2 min after as many as 300 cycles. The desorption kinetics, on the other hand, remain rapid and stable, and complete desorption of 4.6 wt.% H is achieved in 1.5 min at ambient desorption pressure. In addition to showing good hydrogen storage performance, multilayers are an excellent model system for studying the relation between microstructure and hydrogen absorption/desorption kinetics.

Microstructural evolution during hydrogen sorption cycling of Mg-FeTi nanolayered composites

International Nuclear Information System (INIS)

Kalisvaart, W.P.; Kubis, Alan; Danaie, Mohsen; Amirkhiz, Babak Shalchi; Mitlin, David

2011-01-01

This paper describes the microstructural evolution of Mg-FeTi mutlilayered hydrogen storage materials during extended cycling. A 28 nm Mg-5 nm FeTi multilayer has comparable performance to a cosputtered material with an equivalent composition (Mg-10%Fe-10%Ti), which is included as a baseline case. At 200 deg. C, the FeTi layers act as a barrier, preventing agglomeration of Mg particles. At 300 deg. C, the initial structure of the multilayer is preserved up to 35 cycles, followed by fracturing of the Mg layers in the in-plane direction and progressive delamination of the FeTi layers as observed by electron microscopy. Concurrently, an increase in the Mg grain size was observed from 32 to 76 nm between cycles 35 and 300. As a result, the absorption kinetics deteriorate with cycling, although 90% of the total capacity is still absorbed within 2 min after as many as 300 cycles. The desorption kinetics, on the other hand, remain rapid and stable, and complete desorption of 4.6 wt.% H is achieved in 1.5 min at ambient desorption pressure. In addition to showing good hydrogen storage performance, multilayers are an excellent model system for studying the relation between microstructure and hydrogen absorption/desorption kinetics.

Ab initio study of structural and mechanical property of solid molecular hydrogens

Science.gov (United States)

Ye, Yingting; Yang, Li; Yang, Tianle; Nie, Jinlan; Peng, Shuming; Long, Xinggui; Zu, Xiaotao; Du, Jincheng

2015-06-01

Ab initio calculations based on density functional theory (DFT) were performed to investigate the structural and the elastic properties of solid molecular hydrogens (H2). The influence of molecular axes of H2 on structural relative stabilities of hexagonal close-packed (hcp) and face-centered cubic (fcc) structured hydrogen molecular crystals were systematically investigated. Our results indicate that for hcp structures, disordered hydrogen molecule structure is more stable, while for fcc structures, Pa3 hydrogen molecular crystal is most stable. The cohesive energy of fcc H2 crystal was found to be lower than hcp. The mechanical properties of fcc and hcp hydrogen molecular crystals were obtained, with results consistent with previous theoretical calculations. In addition, the effects of zero point energy (ZPE) and van der Waals (vdW) correction on the cohesive energy and the stability of hydrogen molecular crystals were systematically studied and discussed.

Hydrogen Absorption in Metal Thin Films and Heterostructures Investigated in Situ with Neutron and X-ray Scattering

Directory of Open Access Journals (Sweden)

Sara J. Callori

2016-05-01

Full Text Available Due to hydrogen possessing a relatively large neutron scattering length, hydrogen absorption and desorption behaviors in metal thin films can straightforwardly be investigated by neutron reflectometry. However, to further elucidate the chemical structure of the hydrogen absorbing materials, complementary techniques such as high resolution X-ray reflectometry and diffraction remain important too. Examples of work on such systems include Nb- and Pd-based multilayers, where Nb and Pd both have strong affinity to hydrogen. W/Nb and Fe/Nb multilayers were measured in situ with unpolarized and polarized neutron reflectometry under hydrogen gas charging conditions. The gas-pressure/hydrogen-concentration dependence, the hydrogen-induced macroscopic film swelling as well as the increase in crystal lattice plane distances of the films were determined. Ferromagnetic-Co/Pd multilayers were studied with polarized neutron reflectometry and in situ ferromagnetic resonance measurements to understand the effect of hydrogen absorption on the magnetic properties of the system. This electronic effect enables a novel approach for hydrogen sensing using a magnetic readout scheme.

Dependence of hydrogen-induced lattice defects and hydrogen embrittlement of cold-drawn pearlitic steels on hydrogen trap state, temperature, strain rate and hydrogen content

International Nuclear Information System (INIS)

Doshida, Tomoki; Takai, Kenichi

2014-01-01

The effects of the hydrogen state, temperature, strain rate and hydrogen content on hydrogen embrittlement susceptibility and hydrogen-induced lattice defects were evaluated for cold-drawn pearlitic steel that absorbed hydrogen in two trapping states. Firstly, tensile tests were carried out under various conditions to evaluate hydrogen embrittlement susceptibility. The results showed that peak 2 hydrogen, desorbed at temperatures above 200 °C as determined by thermal desorption analysis (TDA), had no significant effect on hydrogen embrittlement susceptibility. In contrast, hydrogen embrittlement susceptibility increased in the presence of peak 1 hydrogen, desorbed from room temperature to 200 °C as determined by TDA, at temperatures higher than −30 °C, at lower strain rates and with higher hydrogen content. Next, the same effects on hydrogen-induced lattice defects were also evaluated by TDA using hydrogen as a probe. Peak 2 hydrogen showed no significant effect on either hydrogen-induced lattice defects or hydrogen embrittlement susceptibility. It was found that hydrogen-induced lattice defects formed under the conditions where hydrogen embrittlement susceptibility increased. This relationship indicates that hydrogen embrittlement susceptibility was higher under the conditions where the formation of hydrogen-induced lattice defects tended to be enhanced. Since hydrogen-induced lattice defects formed by the interaction between hydrogen and strain were annihilated by annealing at a temperature of 200 °C, they were presumably vacancies or vacancy clusters. One of the common atomic-level changes that occur in cold-drawn pearlitic steel showing higher hydrogen embrittlement susceptibility is the formation of vacancies and vacancy clusters

Metal-loaded SBA-16-like silica – Correlation between basicity and affinity towards hydrogen

International Nuclear Information System (INIS)

Ouargli-Saker, R.; Bouazizi, N.; Boukoussa, B.; Barrimo, Diana; Paola-Nunes-Beltrao, Ana; Azzouz, A.

2017-01-01

Highlights: • Metal dispersion in longitudinal channels confers adsorption properties to SBA-16. • Both Fe"0-NPs and Cu"0-NPs seem to be responsible of this effect. • Effect of the repetitive adsorption-desorption cycles on CO_2 and water sorption. • Hydrogen storage on the functionalized materials. - Abstract: Nanoparticles of Cu"o (CuNPs) and Fe"o (FeNPs) were dispersed in SBA-16-like silica, resulting metal-loaded materials (Cu-SBA-16 and Fe-SBA-16) with improved affinity towards hydrogen. Electron microscopy and X-ray diffraction showed that MNP dispersion occurs mainly inside SBA-16 channels. MNP incorporation was found to confer affinity to the silica surface, since higher CO_2 retention capacity (CRC) was registered Cu/SBA-16 and Fe/SBA-16. This was accompanied by a significant improvement of the affinity towards hydrogen, as supported by hydrogen adsorption tests. This was explained in terms of strong hydrogen interaction with MNP and lattice oxygen atoms. The results reported herein open new prospects for SBA-16 as potential adsorbents for hydrogen storage.

Metal-loaded SBA-16-like silica – Correlation between basicity and affinity towards hydrogen

Energy Technology Data Exchange (ETDEWEB)

Ouargli-Saker, R. [Department of Materials Engineering, University of Science and Technology, El M’naouer, BP 1505, Oran (Algeria); Nanoqam, Department of Chemistry, University of Quebec at Montreal, H3C3P8 (Canada); Bouazizi, N. [Nanoqam, Department of Chemistry, University of Quebec at Montreal, H3C3P8 (Canada); Unité de recherche, Electrochimie, Matériaux et Environnement, Faculté des Sciences de Gabès, Université de Gabès, Cité Erriadh, 6072 Gabès (Tunisia); Boukoussa, B. [Department of Materials Engineering, University of Science and Technology, El M’naouer, BP 1505, Oran (Algeria); Lqamb, Laboratório de Química Analítica Ambiental, Faculdade de Química, Pontifícia Universidade Católica do Rio Grande do Sul (Brazil); Barrimo, Diana [Nanoqam, Department of Chemistry, University of Quebec at Montreal, H3C3P8 (Canada); Paola-Nunes-Beltrao, Ana [Nanoqam, Department of Chemistry, University of Quebec at Montreal, H3C3P8 (Canada); Laboratory of Materials Chemistry L.C.M, University of Oran1 Ahmed Ben Bella, BP 1524, El-Mnaouer, 31000 Oran (Algeria); Azzouz, A., E-mail: azzouz.a@uqam.ca [Nanoqam, Department of Chemistry, University of Quebec at Montreal, H3C3P8 (Canada)

2017-07-31

Highlights: • Metal dispersion in longitudinal channels confers adsorption properties to SBA-16. • Both Fe{sup 0}-NPs and Cu{sup 0}-NPs seem to be responsible of this effect. • Effect of the repetitive adsorption-desorption cycles on CO{sub 2} and water sorption. • Hydrogen storage on the functionalized materials. - Abstract: Nanoparticles of Cu{sup o} (CuNPs) and Fe{sup o} (FeNPs) were dispersed in SBA-16-like silica, resulting metal-loaded materials (Cu-SBA-16 and Fe-SBA-16) with improved affinity towards hydrogen. Electron microscopy and X-ray diffraction showed that MNP dispersion occurs mainly inside SBA-16 channels. MNP incorporation was found to confer affinity to the silica surface, since higher CO{sub 2} retention capacity (CRC) was registered Cu/SBA-16 and Fe/SBA-16. This was accompanied by a significant improvement of the affinity towards hydrogen, as supported by hydrogen adsorption tests. This was explained in terms of strong hydrogen interaction with MNP and lattice oxygen atoms. The results reported herein open new prospects for SBA-16 as potential adsorbents for hydrogen storage.

Hydrogenation of ethylene over PrCo5Hsub(2.4)

International Nuclear Information System (INIS)

Soga, Kazuo; Imamura, Hayao; Ikeda, Sakuji

1977-01-01

To elucidate the chemical reactivity of the hydrogen atom absorbed in the hydrogenated alloy PrCo 5 H sub(n), the hydrogenation of ethylene was carried out over PrCo 5 Hsub(2.4) in the absence (A) or presence (B) of hydrogen in gas phase. PrCo 5 Hsub(2.4) was prepared from PrCo 5 according to an ordinary procedure with repeated heating and cooling in hydrogen atmosphere. The hydrogenation of ethylene was conducted at about -70 0 C in a conventional gas circulation system in a pressure range of ethylene 5 -- 16 cmHg and hydrogen 0 -- 38.0 cmHg. The hydrogenation rate was followed by gas chromatography. In the case of (A), the total gas pressure in the gas phase remained constant during the reaction. The hydrogenation rate was independent of the partial pressure of ethylene and it increased in proportion to the concentration of the absorbed hydrogen atom. The rate of desorption of the absorbed hydrogen atom from PrCo 5 Hsub(2.4) also measured under a reduced pressure. The desorption rate was approximately the same as the hydrogenation rate under the similar conditions. From these results, it was concluded that the migration process of the absorbed hydrogen atom from the bulk of the alloy to its surface was rate-determining. In the case of (B), on the other hand, the hydrogenation rate was accelerated by the gaseous hydrogen; the rate increased almost linearly with increasing pressure of hydrogen. The hydrogenation of ethylene was also conducted over PrCo 5 under the similar conditions. (auth.)

Optical hydrogen sensors based on metal-hydrides

Science.gov (United States)

Slaman, M.; Westerwaal, R.; Schreuders, H.; Dam, B.

2012-06-01

For many hydrogen related applications it is preferred to use optical hydrogen sensors above electrical systems. Optical sensors reduce the risk of ignition by spark formation and are less sensitive to electrical interference. Currently palladium and palladium alloys are used for most hydrogen sensors since they are well known for their hydrogen dissociation and absorption properties at relatively low temperatures. The disadvantages of palladium in sensors are the low optical response upon hydrogen loading, the cross sensitivity for oxygen and carbon, the limited detection range and the formation of micro-cracks after some hydrogen absorption/desorption cycles. In contrast to Pd, we find that the use of magnesium or rear earth bases metal-hydrides in optical hydrogen sensors allow tuning of the detection levels over a broad pressure range, while maintaining a high optical response. We demonstrate a stable detection layer for detecting hydrogen below 10% of the lower explosion limit in an oxygen rich environment. This detection layer is deposited at the bare end of a glass fiber as a micro-mirror and is covered with a thin layer of palladium. The palladium layer promotes the hydrogen uptake at room temperature and acts as a hydrogen selective membrane. To protect the sensor for a long time in air a final layer of a hydrophobic fluorine based coating is applied. Such a sensor can be used for example as safety detector in automotive applications. We find that this type of fiber optic hydrogen sensor is also suitable for hydrogen detection in liquids. As example we demonstrate a sensor for detecting a broad range of concentrations in transformer oil. Such a sensor can signal a warning when sparks inside a high voltage power transformer decompose the transformer oil over a long period.

Review of thermodinamic and mechanical properties of hydrogen-transition metal systems

International Nuclear Information System (INIS)

Mathias, H.; Katz, Y.

1978-04-01

A large body of fundamental and empirical knowledge has been acquired during many years of research concerning the interactions between hydrogen and metals, the location of hydrogen in metal structures, its mobility in metals and its influence on mechanical properties of metals. Much progress has been made in the understanding of related phenomena, and various theories have been proposed, but considerable disagreement still exist about basic mechanisms involved. The growing interest in these subjects and their important role in science and technology are well documented by many reviews and symposia. A general survey of these topics with reference to experimental results and theories related to thermodynamic and mechanical properties of hydrogen-transition metal systems, such as H-Pd, H-Ti, H-Fe etc. is given in the present review. Special emphasis is given to hydrogen embrittlement of metals

Catalyzed Nano-Framework Stablized High Density Reversible Hydrogen Storage Systems

Energy Technology Data Exchange (ETDEWEB)

Tang, Xia [value too long for type character varying(50); Opalka, Susanne M.; Mosher, Daniel A; Laube, Bruce L; Brown, Ronald J; Vanderspurt, Thomas H; Arsenault, Sarah; Wu, Robert; Strickler, Jamie; Ronnebro, Ewa; Boyle, Tim; Cordaro, Joseph

2010-06-30

A wide range of high capacity on-board rechargeable material candidates have exhibited non-ideal behavior related to irreversible hydrogen discharge / recharge behavior, and kinetic instability or retardation. This project addresses these issues by incorporating solvated and other forms of complex metal hydrides, with an emphasis on borohydrides, into nano-scale frameworks of low density, high surface area skeleton materials to stabilize, catalyze, and control desorption product formation associated with such complex metal hydrides. A variety of framework chemistries and hydride / framework combinations were investigated to make a relatively broad assessment of the method's potential. In this project, the hydride / framework interactions were tuned to decrease desorption temperatures for highly stable compounds or increase desorption temperatures for unstable high capacity compounds, and to influence desorption product formation for improved reversibility. First principle modeling was used to explore heterogeneous catalysis of hydride reversibility by modeling H₂ dissociation, hydrogen migration, and rehydrogenation. Atomic modeling also demonstrated enhanced NaTi(BH₄)₄ stabilization at nano-framework surfaces modified with multi-functional agents. Amine multi-functional agents were found to have more balanced interactions with nano-framework and hydride clusters than other functional groups investigated. Experimentation demonstrated that incorporation of Ca(BH₄)₂ and Mg(BH₄)₂ in aerogels enhanced hydride desorption kinetics. Carbon aerogels were identified as the most suitable nano-frameworks for hydride kinetic enhancement and high hydride loading. High loading of NaTi(BH₄)₄ ligand complex in SiO₂ aerogel was achieved and hydride stability was improved with the aerogel. Although improvements of desorption kinetics was observed, the incorporation of

Hydrogen isotope effect on storage behavior of U{sub 2}Ti and UZr{sub 2.3}

Energy Technology Data Exchange (ETDEWEB)

Jat, Ram Avtar; Sawant, S.G.; Rajan, M.B.; Dhanuskar, J.R. [Product Development Division, Bhabha Atomic Research Centre, Trombay, Mumbai 400 085 (India); Kaity, Santu [Radiometallurgy Division, Bhabha Atomic Research Centre, Trombay, Mumbai 400 085 (India); Parida, S.C., E-mail: sureshp@barc.gov.in [Product Development Division, Bhabha Atomic Research Centre, Trombay, Mumbai 400 085 (India)

2013-11-15

U{sub 2}Ti and UZr{sub 2.3} alloys were prepared by arc melting method, vacuum annealed and characterized by XRD, SEM and EDX methods. Hydrogen isotope effect on the storage behavior of these alloys were studied by measuring the hydrogen/deuterium desorption pressure–composition–temperature (PCT) profiles in the temperature range of 573–678 K using a Sievert’s type volumetric apparatus. It was observed that, in the temperature and pressure range of investigation, all the isotherms show a single desorption plateau. The PCT data reveals that both U{sub 2}Ti and UZr{sub 2.3} alloys had normal isotope effects on hydrogen/deuterium desorption at all experimental temperatures. Thermodynamic parameters for dehydrogenation and dedeuteration reactions of the corresponding hydrides and deuterides of the above alloys were deduced from the PCT data.

Electron Stimulated Desorption of Condensed Gases on Cryogenic Surfaces

CERN Document Server

Tratnik, H; Hilleret, Noël

2005-01-01

In ultra-high vacuum systems outgassing from vacuum chamber walls and desorption from surface adsorbates are usually the factors which in°uence pressure and residual gas composition. In particular in beam vacuum systems of accelerators like the LHC, where surfaces are exposed to intense synchro- tron radiation and bombardment by energetic ions and electrons, properties like the molecular desorption yield or secondary electron yield can strongly in°uence the performance of the accelerator. In high-energy particle accelerators operating at liquid helium temperature, cold surfaces are exposed to the bombardment of energetic photons, electrons and ions. The gases released by the subsequent desorption are re-condensed on the cold surfaces and can be re-desorbed by the impinging electrons and ions. The equilibrium coverage reached on the surfaces exposed to the impact of energetic particles depends on the desorption yield of the condensed gases and can a®ect the operation of the accelerator by modifying th...

Hydrogen storage in MgH2 - LaNi5 nanocomposites produced by cold rolling under inert atmosphere

International Nuclear Information System (INIS)

Marquez, J.J.; Silva, W.B.; Leiva, D.R.; Ishikawa, T.T.; Kiminami, C.S.; Botta, W.J.; Floriano, R.

2016-01-01

In this study, the effects of the addition of LaNi5 in magnesium hydride H-sorption/desorption behavior was addressed. MgH 2 - X mol.% LaNi 5 (X=0.67; 1.50 and 2.54) mixtures were processed by cold rolling (CR) inside a glove box under controlled atmosphere, with oxygen and moisture contents below 0.1 ppm. Structural characterization showed that during the H-absorption/desorption cycles, a mixture of phases consisting of MgH 2 , LaH 3 and Mg 2 NiH 4 is formed, which has an important role in the hydrogen storage kinetic properties. The mixture MgH 2 -1.50 mol.% LaNi 5 was able to absorb/desorb 4.0 wt.% H 2 in less than 15 min at 100 and 280 °C respectively. The DSC analysis showed that the LaNi 5 additive lowers the temperature at which the H-desorption starts in cold rolled MgH 2 by around 50 °C. (author)

Hysteresis-free nanoplasmonic pd-au alloy hydrogen sensors

DEFF Research Database (Denmark)

Wadell, Carl; Nugroho, Ferry Anggoro Ardy; Lidström, Emil

2015-01-01

hydrogen sensors. By increasing the amount of Au in the alloy nanoparticles up to 25 atom %, we are able to suppress the hysteresis between hydrogen absorption and desorption, thereby increasing the sensor accuracy to below 5% throughout the investigated 1 mbar to 1 bar hydrogen pressure range. Furthermore......, we observe an 8-fold absolute sensitivity enhancement at low hydrogen pressures compared to sensors made of pure Pd, and an improved sensor response time to below one second within the 0-40 mbar pressure range, that is, below the flammability limit, by engineering the nanoparticle size....

Sputtered Pd as hydrogen storage for a chip-integrated microenergy system.

Science.gov (United States)

Slavcheva, E; Ganske, G; Schnakenberg, U

2014-01-01

The work presents a research on preparation and physical and electrochemical characterisation of dc magnetron sputtered Pd films envisaged for application as hydrogen storage in a chip-integrated hydrogen microenergy system. The influence of the changes in the sputtering pressure on the surface structure, morphology, and roughness was analysed by X-ray diffraction (XRD), scanning electron microscopy (SEM), and atomic force microscopy (AMF). The electrochemical activity towards hydrogen adsorption/desorption and formation of PdH were investigated in 0.5 M H2SO4 using the methods of cyclic voltammetry and galvanostatic polarisation. The changes in the electrical properties of the films as a function of the sputtering pressure and the level of hydrogenation were evaluated before and immediately after the electrochemical charging tests, using a four-probe technique. The research resulted in establishment of optimal sputter regime, ensuring fully reproducible Pd layers with highly developed surface, moderate porosity, and mechanical stability. Selected samples were integrated as hydrogen storage in a newly developed unitized microenergy system and tested in charging (water electrolysis) and discharging (fuel cell) operative mode at ambient conditions demonstrating a stable recycling performance.

Study of the mechanisms of heavy-ion induced desorption on accelerator-relevant materials

International Nuclear Information System (INIS)

Bender, Markus

2008-01-01

The ion beam loss induced desorption is a performance limitation for low charge state heavy ion accelerators. If charge exchanged projectile ions get lost onto the beam pipe, desorption of gas is stimulated resulting in a pressure increase inside of the synchrotron and thus, a dramatically reduction of the beam life time. To minimize the amount of desorbed gas an experimental program has been started to measure the desorption yields (released gas molecules per incident ion) of various materials and different projectile ions. The present work is a contribution to the understanding of the physical processes behind the ion beam loss induced desorption. The yield measurements by the pressure rise method have been combined for the rst time with in situ ion beam analysis technologies such as ERDA and RBS. With this unique method the desorption behavior of a sample can be correlated to its surface and bulk properties. The performed experiments with 1,4 MeV/u Xenon-Ions show that the ion induced desorption is mainly a surface effect. Sputtered oxide layers or impurities do not contribute to the desorbed gas significantly. Nevertheless bulk properties play an important role in the desorption strength. Pure metallic samples desorb less gas than isolating materials under swift heavy ion irradiation. From the experimental results it was possible to estimate the desorption yields of various materials under ion bombardment by means of an extended inelastic thermal-spike-model. The extension is the combination of the thermal-spike's temperature map with thermal desorption. Within this model the ion induced desorption can be regarded as the release of adsorbates from a transient overheated spot on the samples surface around the ion impact. Finally a copper substrate with a gold coated surface was developed and proposed as a suitable material for a beam loss collimator with minimum desorption to ensure the performance of GSI's SIS18 in high current beam operation. (orig.)

The effect of hydrogen absorption on the electrical resistivities of SmCo5 and LaNi5 films

International Nuclear Information System (INIS)

Sakaguchi, H.; Nagai, H.; Adachi, G.; Shiokawa, J.

1985-01-01

Many studies have been carried out to clarify the absorption mechanism of hydrogen with a bulk of hexagonal CaCu 5 -type intermetallic compounds, such as LaNi 5 . The studies on films, however, have been scarcely carried out because of the difficulty in preparing an intermetallic compound film owing to the difference in the vapour pressure of the component metals. Some homogeneous LaNi 5 films were obtained by the authors using the technique of flash evaporation. Then it was found that they do not pulverize during the hydrogen absorption-desorption cycle. Therefore, it has been possible to measure the electrical resistivity using such films. The objects of our study were to reveal the mechanism of hydrogen absorption through the electrical property, and to apply the film to the functional materials, for instance, a hydrogen separation film. The hydrogen separation was attempted by the authors using the LaNi 5 film. A SmCo 5 film was a suitable candidate because the mass of hydrogen contained in this film should be smaller than that in the LaNi 5 film. In this paper we present a study on the properties of SmCo 5 films under a hydrogen atmosphere, as well as on LaNi 5 films. (author)

Study of the polymer permanent magnets properties - rare earths

International Nuclear Information System (INIS)

Takiishi, H.; Benini, H.R.; Lima, L.F.C.P.; Faria, R.N.

1996-01-01

An alternative method for permanent magnet production without the sintering step is polymer bonded magnets. In this work magnets were prepared from magnetic Sm Co 5 or Nd 15 Fe 77 B 8 alloys bonded with 10% wt of resin. For the Nd 15 Fe 77 B 8 alloy the hydrogenation - decomposition - desorption - recombination (HDDR) process have been employed in the preparation of the magnets. Results from the magnetic properties showed that no milling is necessary for the production of polymer bonded Nd-Fe-B magnets. The magnets showed good magnetic properties. (author)

Electronic and magnetic properties of pristine and hydrogenated borophene nanoribbons

Science.gov (United States)

Meng, Fanchen; Chen, Xiangnan; Sun, Songsong; He, Jian

2017-07-01

The groundbreaking works in graphene and graphene nanoribbons (GNRs) over the past decade, and the very recent discovery of borophene naturally draw attention to the yet-to-be-explored borophene nanoribbons (BNRs). We herein report a density functional theory (DFT) study of the electronic and magnetic properties of BNRs. The foci are the impact of orientation (denoted as BxNRs and ByNRs with their respective periodic orientations along x- and y-axis), ribbon width (Nx, Ny=4-15), and hydrogenation effects on the geometric, electronic and magnetic properties of BNRs. We found that the anisotropic quasi-planar geometric structure of BNR and the edge states largely govern its electronic and magnetic properties. In particular, pristine ByNRs adopt a magnetic ground state, either anti-ferromagnetic (AFM) or ferromagnetic (FM) depending on the ribbon width, while pristine BxNRs are non-magnetic (NM). Upon hydrogenation, all BNRs exhibit NM. Interestingly, both pristine and hydrogenated ByNRs undergo a metal-semiconductor-metal transition at Ny=7, while all BxNRs remain metallic.

Effect of MoS2 on hydrogenation storage properties of LiBH4

International Nuclear Information System (INIS)

Liang, Dan; Han, Shumin; Wang, Jiasheng; Zhang, Wei; Zhao, Xin; Zhao, Ziyang

2014-01-01

The hydrogen storage properties of LiBH 4 ball milled with 20 wt% MoS 2 have been investigated. It shows that the LiBH 4 doped with MoS 2 exhibits favorable hydrogenation and dehydrogenation properties in terms of decomposition temperature and hydriding/dehydriding reversibility. The sample with MoS 2 starts to release hydrogen at 230 °C and has a decrease of 80 °C in contrast with pristine LiBH 4 . Furthermore, for the second cycle, the LiBH 4 with MoS 2 maintains a reversible hydrogen storage capacity of about 8.0 wt% which is almost identical with the first cycle under 5 MPa at 550 °C. Analyzed by the XRD and the FTIR results, LiBH 4 can be regenerated after re-hydrogenation under a relatively mild condition by adding MoS 2 . The improvement of the hydrogenation and dehydrogenation properties mainly results from the formation of Li 2 S and MoB 2 during ball milling. -- Graphical abstract: Hydrogen absorption curves of LiBH 4 doped with MoS 2 for five cycles at 400 °C. Highlights: • The hydrogen absorption capacity is nearly the same for 5 cycles at 400 °C. • The sample with MoS 2 starts to release hydrogen at 230 °C. • The coexistence of MoB 2 and Li 2 S catalyzes the decomposition of LiBH 4

Effects of chemical oxidation on sorption and desorption of PAHs in typical Chinese soils

International Nuclear Information System (INIS)

Chen Wei; Hou Lei; Luo Xiaoli; Zhu Lingyan

2009-01-01

In situ chemical oxidation is a commonly applied soil and groundwater remediation technology, but can have significant effects on soil properties, which in turn might affect fate and transport of organic contaminants. In this study, it was found that oxidation treatment resulted mainly in breakdown of soil organic matter (SOM) components. Sorption of naphthalene and phenanthrene to the original soils and the KMnO 4 -treated soils was linear, indicating that hydrophobic partitioning to SOM was the predominant mechanism for sorption. Desorption from the original and treated soils was highly resistant, and was well modeled with a biphasic desorption model. Desorption of residual naphthalene after treating naphthalene-contaminated soils with different doses of KMnO 4 also followed the biphasic desorption model very well. It appears that neither changes of soil properties caused by chemical oxidation nor direct chemical oxidation of contaminated soils had a noticeable effect on the nature of PAH-SOM interactions. - Chemical oxidation of soils had little effect on the mechanisms controlling sorption and desorption of PAHs.

Cellular automaton model for hydrogen transport dynamics through metallic surface

International Nuclear Information System (INIS)

Shimura, K.; Yamaguchi, K.; Terai, T.; Yamawaki, M.

2002-01-01

Hydrogen re-emission and re-combination at the surface of first wall materials are a crucial issue for the understanding of the fuel recycling and for the tritium inventory in plasma facing materials. It is know to be difficult to model the transient behaviour of those processes due to their complex time-transient nature. However, cellular automata (CA) are powerful tools to model such complex systems because of their nature of discreteness in both dependent and independent variables. Then the system can be represented by the fully local interactions between cells. For that reason, complex physical and chemical systems can be described by fairly simple manner. In this study, the kinetics of desorption of adsorbed hydrogen from an ideal metallic surface is modelled in CA. Thermal desorption is simulated with this model and the comparison with the theory of rate processes is performed to identify the validity of this model. The overall results show that this model is reasonable to express the desorption kinetics

Hydrogen storage in carbon nano-materials. Elaboration, characterization and properties

International Nuclear Information System (INIS)

Luxembourg, D.

2004-10-01

This work deals with hydrogen storage for supplying fuel cells. Hydrogen storage by adsorption in carbon nano-tubes and nano-fibers is a very controversial issue because experimental results are very dispersed and adsorption mechanisms are not yet elucidated. Physi-sorption cannot explain in fact all the experimental results. All the potential adsorption sites, physical and chemical, are discussed as detailed as possible in a state of the art. Experimental works includes the steps of elaboration, characterization, and measurements of the hydrogen storage properties. Nano-fibers are grown using a CVD approach. Single wall carbon nano-tubes (SWNT) synthesis is based on the vaporization/condensation of a carbon/catalysts mixture in a reactor using a fraction of the available concentrated solar energy at the focus of the 1000 kW solar facility of IMP-CNRS at Odeillo. Several samples are produced using different synthesis catalysts (Ni, Co, Y, Ce). SWNT samples are purified using oxidative and acid treatments. Hydrogen storage properties of these materials are carefully investigated using a volumetric technique. The applied pressure is up to 6 MPa and the temperature is 253 K. Hydrogen uptake of the investigated materials are less than 1 % wt. at 253 K and 6 MPa. (author)

Sustainable hydrogen - A challenge for materials science and equipment design

International Nuclear Information System (INIS)

Duta, Anca; Enesca, Alexandru Ioan; Perniu, Dana

2006-01-01

Full text: Hydrogen is the ideal fuel, considering its fully non-polluting by-products. Still, in discussions on 'sustainable hydrogen', there must be considered all the steps implied in hydrogen production, storage and use and the overall energy balance represents the real starting point of evaluating the sustainability. So far, hydrogen production is related to rather energy-consuming processes; extended research is devoted to develop high efficiency processes, but the industrial hydrogen production makes use of either large electrical or thermal energy amounts. Hydrogen production via water photolysis represents, consequently a viable alternative although many steps have to be elaborated to reached the industrial scale of these processes. Hydrogen storing represents another problem that affects its application; a safe storage way, in metal hydrides, is still under intensive research all over the world. The group of the Centre of Product Design for Sustainable Development is engaged in research for developing a laboratory photolyser, able to produce hydrogen and to offer an efficient storage alternative. The photolyser is a photo-electrochemical cell, and the efficiency of the photolysis process depends on several factors: - the photo-electrodes: thin films of wide band gap semiconductors with tailored properties; - the aqueous environment, with effect on the electrode materials properties and stability; - the external bias; - the cell design. The paper focuses mainly on the photo-electrode materials that were tested. The influence of the composition, crystalline and defect structure, of the morphology and of the interfaces on the photolysis process are reviewed. The effect of the pH in the aqueous media is discussed along with the stability of the materials and the reversibility of the adsorption/desorption processes. The design criteria that must be fulfilled in developing the photolyser are also discussed. (authors)

Experimental and theoretical investigation of Fe-catalysis phenomenon in hydrogen thermal desorption form hydrocarbon plasma-discharge films from T-10 tokamak

International Nuclear Information System (INIS)

Stankevich, V.G.; Svechnikov, N.Y.; Lebedev, A.M.; Menshikov, K.A.; Kolbasov, B.N.; Sukhanov, L.P.

2017-01-01

A comprehensive study of hydrocarbon films obtained in the plasma discharge of large fusion facilities will allow the minimization of parasitic capture. The investigation of the effect of Fe impurities on D 2 thermal desorption (TD) from homogeneous CD x films (x ∼ 0.5) formed in the D-plasma discharge of the T-10 tokamak were carried out. The experimental TD spectra of the films showed 2 groups of peaks at 650-850 K and 900-1000 K for 2 adsorption states. The main result of the iron catalysis effect consists in the shift of the high-temperature peak by -24 K and in the increase in the fraction of the weakly bonded adsorption states. To describe the effect of iron impurities on TD of hydrogen isotopes, a structural cluster model based on the interaction of the Fe + ion with the 1,3-C 6 H 8 molecule was proposed. The potential energy surfaces of chemical reactions with the H 2 elimination were calculated using ab initio methods of quantum chemistry. It was established that the activation barrier of hydrogen TD is reduced by about 1 eV due to the interaction of the Fe + ion with the π-subsystem of the 1,3-C 6 H 8 molecule leading to a redistribution of the double bonds along the carbon system

Experimental and theoretical investigation of Fe-catalysis phenomenon in hydrogen thermal desorption from hydrocarbon plasma-discharge films from T-10 tokama

Science.gov (United States)

Stankevich, Vladimir G.; Sukhanov, Leonid P.; Svechnikov, Nicolay Yu.; Lebedev, Alexey M.; Menshikov, Kostantin A.; Kolbasov, Boris N.

2017-10-01

Investigations of the effect of Fe impurities on D2 thermal desorption (TD) from homogeneous CDx films (x ˜ 0.5) formed in the D-plasma discharge of the T-10 tokamak were carried out. The experimental TD spectra of the films showed two groups of peaks at 650-850 K and 900-1000 K for two adsorption states. The main result of the iron catalysis effect consists in the shift of the high-temperature peak by -24 K and in the increase in the fraction of the weakly bonded adsorption states. To describe the effect of iron impurities on TD of hydrogen isotopes, a structural cluster model based on the interaction of the Fe+ ion with the 1,3-C6H8 molecule was proposed. The potential energy surfaces of chemical reactions with the H2 elimination were calculated using ab initio methods of quantum chemistry. It was established that the activation barrier of hydrogen TD is reduced by about 1 eV due to the interaction of the Fe+ ion with the π-subsystem of the 1,3-C6H8 molecule leading to a redistribution of the double bonds along the carbon system. Contribution to the topical issue "Plasma Sources and Plasma Processes (PSPP)"", edited by Luis Lemos Alves, Thierry Belmonte and Tiberiu Minea

Influence of cold deformation and annealing on hydrogen embrittlement of cold hardening bainitic steel for high strength bolts

Energy Technology Data Exchange (ETDEWEB)

Hui, Weijun, E-mail: wjhui@bjtu.edu.cn [School of Mechanical, Electronic and Control Engineering, Beijing Jiaotong University, Beijing 100044 (China); Zhang, Yongjian; Zhao, Xiaoli; Shao, Chengwei [School of Mechanical, Electronic and Control Engineering, Beijing Jiaotong University, Beijing 100044 (China); Wang, Kaizhong; Sun, Wei; Yu, Tongren [Technical Center, Maanshan Iron & Steel Co., Ltd., Maanshan 243002, Anhui (China)

2016-04-26

The influence of cold drawing and annealing on hydrogen embrittlement (HE) of newly developed cold hardening bainitic steel was investigated by using slow strain rate testing (SSRT) and thermal desorption spectrometry (TDS), for ensuring safety performance of 10.9 class high strength bolts made of this kind of steel against HE under service environments. Hydrogen was introduced into the specimen by electrochemical charging. TDS analysis shows that the hydrogen-charged cold drawn specimen exhibits an additional low-temperature hydrogen desorption peak besides the original high-temperature desorption peak of the as-rolled specimen, causing remarkable increase of absorbed hydrogen content. It is found that cold drawing significantly enhances the susceptibility to HE, which is mainly attributed to remarkable increase of diffusible hydrogen absorption, the occurrence of strain-induced martensite as well as the increase of strength level. Annealing after cold deformation is an effective way to improve HE resistance and this improvement strongly depends on annealing temperature, i.e. HE susceptibility decreases slightly with increasing annealing temperature up to 200 °C and then decreases significantly with further increasing annealing temperature. This phenomenon is explained by the release of hydrogen, the recovery of cold worked microstructure and the decrease of strength with increasing annealing temperature.

Standardized Testing Program for Solid-State Hydrogen Storage Technologies

Energy Technology Data Exchange (ETDEWEB)

Miller, Michael A. [Southwest Research Institute; Page, Richard A. [Southwest Research Institute

2012-07-30

established and qualified standards. Working with industry, academia, and the U.S. government, SwRI set out to develop an accepted set of evaluation standards and analytical methodologies. Critical measurements of hydrogen sorption properties in the Laboratory have been based on three analytical capabilities: 1) a high-pressure Sievert-type volumetric analyzer, modified to improve low-temperature isothermal analyses of physisorption materials and permit in situ mass spectroscopic analysis of the sample’s gas space; 2) a static, high-pressure thermogravimetric analyzer employing an advanced magnetic suspension electro-balance, glove-box containment, and capillary interface for in situ mass spectroscopic analysis of the sample’s gas space; and 3) a Laser-induced Thermal Desorption Mass Spectrometer (LTDMS) system for high thermal-resolution desorption and mechanistic analyses. The Laboratory has played an important role in down-selecting materials and systems that have emerged from the MCoEs.

The study of hydrogen electrosorption in layered nickel foam/palladium/carbon nanofibers composite electrodes

International Nuclear Information System (INIS)

Skowronski, J.M.; Czerwinski, A.; Rozmanowski, T.; Rogulski, Z.; Krawczyk, P.

2007-01-01

In the present work, the process of hydrogen electrosorption occurring in alkaline KOH solution on the nickel foam/palladium/carbon nanofibers (Ni/Pd/CNF) composite electrodes is examined. The layered Ni/Pd/CNF electrodes were prepared by a two-step method consisting of chemical deposition of a thin layer of palladium on the nickel foam support to form Ni/Pd electrode followed by coating the palladium layer with carbon nanofibers layer by means of the CVD method. The scanning electron microscope was used for studying the morphology of both the palladium and carbon layer. The process of hydrogen sorption/desorption into/from Ni/Pd as well as Ni/Pd/CNF electrode was examined using the cyclic voltammetry method. The amount of hydrogen stored in both types of composite electrodes was shown to increase on lowering the potential of hydrogen sorption. The mechanism of the anodic desorption of hydrogen changes depending on whether or not CNF layer is present on the Pd surface. The anodic peak corresponding to the removal of hydrogen from palladium is lower for Ni/Pd/CNF electrode as compared to that measured for Ni/Pd one due to a partial screening of the Pd surface area by CNF layer. The important feature of Ni/Pd/CNF electrode is anodic peak appearing on voltammetric curves at potential ca. 0.4 V more positive than the peak corresponding to hydrogen desorption from palladium. The obtained results showed that upon storing the hydrogen saturated Ni/Pd/CNF electrode at open circuit potential, diffusion of hydrogen from carbon to palladium phase occurs due to interaction between carbon fibers and Pd sites on the nickel foam support

Surface Magnetism of Cobalt Nanoislands Controlled by Atomic Hydrogen.

Science.gov (United States)

Park, Jewook; Park, Changwon; Yoon, Mina; Li, An-Ping

2017-01-11

Controlling the spin states of the surface and interface is key to spintronic applications of magnetic materials. Here, we report the evolution of surface magnetism of Co nanoislands on Cu(111) upon hydrogen adsorption and desorption with the hope of realizing reversible control of spin-dependent tunneling. Spin-polarized scanning tunneling microscopy reveals three types of hydrogen-induced surface superstructures, 1H-(2 × 2), 2H-(2 × 2), and 6H-(3 × 3), with increasing H coverage. The prominent magnetic surface states of Co, while being preserved at low H coverage, become suppressed as the H coverage level increases, which can then be recovered by H desorption. First-principles calculations reveal the origin of the observed magnetic surface states by capturing the asymmetry between the spin-polarized surface states and identify the role of hydrogen in controlling the magnetic states. Our study offers new insights into the chemical control of magnetism in low-dimensional systems.

Two approaches for enhancing the hydrogenation properties of ...

Indian Academy of Sciences (India)

Wintec

ties of Pd. In the first approach, metal thin film (Cu, Ag) has been deposited over Pd and hydrogenation properties of ... Firstly, the critical temperature of miscibility gap for the α to β phase ... diffraction (GAXRD) studies have been done. 18. The.

Nanocrystalline electrodeposited Ni-Mo-C cathodes for hydrogen production

International Nuclear Information System (INIS)

Hashimoto, K.; Sasaki, T.; Meguro, S.; Asami, K.

2004-01-01

Tailoring active nickel alloy cathodes for hydrogen evolution in a hot concentrated hydroxide solution was attempted by electrodeposition. The carbon addition to Ni-Mo alloys decreased the nanocrystalline grain size and remarkably enhanced the activity for hydrogen evolution, changing the mechanism of hydrogen evolution. The Tafel slope of hydrogen evolution was about 35 mV per decade. This suggested that the rate-determining step is desorption of adsorbed hydrogen atoms by recombination. As was distinct from the binary Ni-Mo alloys, after open circuit immersion, the overpotential, that is, the activity of nanocrystalline Ni-Mo-C alloys for hydrogen evolution was not changed, indicating the sufficient durability in the practical electrolysis

Interaction of hydrogen and its isotopes with irradiated beryllium

International Nuclear Information System (INIS)

Tazhibaeva, I.L.; Shestakov, V.P.; Klepikov, A.Kh.; Pomanenko, O.G.; Chikhraj, E.V.; Kenzhin, E.A.; Zverev, V.V.; Kolbanenkov, A.N.

2000-01-01

In the article the results of experiments on hydrogen and its isotopes accumulation and gas-release from irradiated beryllium are presented. The irradiation was conducted at different media and temperatures in the RA and IVG.1M reactors. The measurements were carried out by thermal desorption method. Hydrogen release from beryllium samples saturated at different conditions were calculated. Dependence of hydrogen confinement character in beryllium from grain orientation in the sample, temperature and irradiation rate was revealed

Structure modification of Mg-Nb films under hydrogen sorption cycles

Energy Technology Data Exchange (ETDEWEB)

Mengucci, P., E-mail: p.mengucci@univpm.it [Dipartimento di Fisica e Ingegneria dei Materiali e del Territorio, Universita Politecnica delle Marche, Via Brecce Bianche, I-60131 Ancona (Italy); Barucca, G.; Majni, G. [Dipartimento di Fisica e Ingegneria dei Materiali e del Territorio, Universita Politecnica delle Marche, Via Brecce Bianche, I-60131 Ancona (Italy); Bazzanella, N.; Checchetto, R.; Miotello, A. [Dipartimento di Fisica, Universita di Trento, Via Sommarive, I-38123 Povo (Italy)

2011-09-15

Research highlights: > Influence of Nb additions on the hydrogen kinetics of Mg layers. > Structure modification of the Mg matrix during hydrogen cycling. > Lattice strains induced by Nb tends to decrease during hydrogen cycling. > Nb nanoparticles form during hydrogen cycling. > Nb enhances the porous structure of the Mg layer formed during hydrogen cycling. - Abstract: In the present work we focus our attention on the structural modifications induced by repeated absorption/desorption cycles on Mg-Nb layers. Samples consisting of a 30 {mu}m thick pure Mg or Mg-5 at.% Nb doped films, coated with a 20 nm thick Pd layer were submitted to repeated H{sub 2} sorption cycles in a volumetric apparatus. Isothermal desorption analysis at 350 deg. C was performed to evaluate the amount of absorbed hydrogen. X-ray diffraction (XRD), energy dispersive spectroscopy (EDS) and electron microscopy techniques (SEM and TEM) were used for the structural characterisation of the samples. Analyses show a deep modification of the material upon cycling. The presence of Nb enhances the structural modifications and induces an initial lattice contraction of the Mg matrix that tends to decrease on cycling via the formation of Nb nanoparticles (with average size of {approx}10 nm). SEM and TEM observations performed in cross section evidenced the formation of a porous structure.

Study of the influence of the temperature in the magnetic properties and in microstructure in the permanent magnets Pr-Fe-B-Nb-Co based obtained by hydrogen

International Nuclear Information System (INIS)

Silva, Suelanny Carvalho da

2007-01-01

Fine magnetic powders were produced using the hydrogenation disproportionation desorption and recombination (HDDR) process. The first stage in this work involved an investigation of the effect of the Co content and range of desorption/ recombination temperatures between 800 and 900 deg C with the purpose of optimizing the HDDR treatment for Pr 14 Fe 80 B 6 and Pr 14 Fe bal Co x B 6 Nb 0,1 (x= 0, 4, 8, 10, 12, 16) alloys. The cast alloys were annealed at 1100 deg C for 20 hours for homogenization. The processing temperature (desorption/ recombination) affected the microstructure and magnetic properties of the bonded magnets. The alloy with low cobalt content (4 at.%) required the highest reaction temperature (880 deg C) to yield anisotropic bonded magnets. The optimum temperature for alloys with 8 at.% Co and 10 at.% Co were 840 deg C and 820 deg C, respectively. Alloys with high cobalt content (12 at.% and 16 at.%) were processed at 840 deg C. The optimum desorption temperature for achieving high anisotropy for Pr 14 Fe 80 B 6 and Pr 14 Fe 79,9 B 6 Nb 0,1 was 820 deg C. The best remanence (862 mT) was achieved with the Pr 14 Fe 67,9 B 6 Co 12 Nb 0,1 magnet, processed at 840 deg C. Each alloy required an optimum reaction temperature and exhibited a particular microstructure according to the composition. The second stage of the work involved the characterization, for each temperature, of the Pr 14 Fe 80 B 6 HDDR powder processed using X-ray diffraction analysis. The samples of the HDDR material were studied by synchrotron radiation powder diffraction using the Rietveld method for cell refinement, phase quantification and crystallite sizes determination. Scanning electron microscopy has also been employed to reveal the morphology of the HDDR powder. (author)

Generation of nanopores during desorption of NH3 from Mg(NH3)6Cl2

DEFF Research Database (Denmark)

Hummelshøj, Jens Strabo; Sørensen, Rasmus Zink; Kostova, M.Y.

2006-01-01

It is shown that nanopores are formed during desorption of NH3 from Mg(NH3)6Cl2, which has been proposed as a hydrogen storage material. The system of nanopores facilitates the transport of desorbed ammonia away from the interior of large volumes of compacted storage material. DFT calculations sh...

Decarbonylation and hydrogenation reactions of allyl alcohol and acrolein on Pd(110)

Science.gov (United States)

Shekhar, Ratna; Barteau, Mark A.

1994-11-01

Allyl alcohol and acrolein reactions on the Pd(110) surface were investigated using temperature programmed desorption. For both unsaturated oxygenates, three coverage-dependent reaction pathways were observed. At low coverages, allyl alcohol decomposed completely to CO, hydrogen and carbonaceous species on the surface. For θ > 0.15 monolayer, ethylene (and small amounts of ethane) desorbed at ca. 295 K. Near saturation coverages, desorption of propanal was detected at ca. 235 K. The parent molecule, allyl alcohol, desorbed only after exposures sufficient to saturate these channels. Acrolein decomposition spectra were similar to those observed for allyl alcohol decomposition on the clean surface. Additional experiments with allyl alcohol on hydrogen- and deuterium-precoveredPd(110) surfaces demonstrated increased hydrogenation of the C 2-hydrocarbon products along with hydrogenation of allyl alcohol to 1-propanol. However, in contrast to previous results for allyl alcohol on the Pd(111) surface, there was no evidence for C-O scission reactions of any C 3 oxygenate on Pd(110).

Nanodiamond for hydrogen storage: temperature-dependent hydrogenation and charge-induced dehydrogenation.

Science.gov (United States)

Lai, Lin; Barnard, Amanda S

2012-02-21

Carbon-based hydrogen storage materials are one of hottest research topics in materials science. Although the majority of studies focus on highly porous loosely bound systems, these systems have various limitations including use at elevated temperature. Here we propose, based on computer simulations, that diamond nanoparticles may provide a new promising high temperature candidate with a moderate storage capacity, but good potential for recyclability. The hydrogenation of nanodiamonds is found to be easily achieved, in agreement with experiments, though we find the stability of hydrogenation is dependent on the morphology of nanodiamonds and surrounding environment. Hydrogenation is thermodynamically favourable even at high temperature in pure hydrogen, ammonia, and methane gas reservoirs, whereas water vapour can help to reduce the energy barrier for desorption. The greatest challenge in using this material is the breaking of the strong covalent C-H bonds, and we have identified that the spontaneous release of atomic hydrogen may be achieved through charging of hydrogenated nanodiamonds. If the degree of induced charge is properly controlled, the integrity of the host nanodiamond is maintained, which indicates that an efficient and recyclable approach for hydrogen release may be possible. This journal is © The Royal Society of Chemistry 2012

Alloying effect on the electronic structures of hydrogen storage compounds

Energy Technology Data Exchange (ETDEWEB)

Yukawa, H.; Moringa, M.; Takahashi, Y. [Nagoya Univ. (Japan). Dept. of Mater. Sci. and Eng.

1997-05-20

The electronic structures of hydrogenated LaNi{sub 5} containing various 3d transition elements were investigated by the DV-X{alpha} molecular orbital method. The hydrogen atom was found to form a strong chemical bond with the Ni rather than the La atoms. The alloying modified the chemical bond strengths between atoms in a small metal octahedron containing a hydrogen atom at the center, resulting in the change in the hydrogen absorption and desorption characteristics of LaNi{sub 5} with alloying. (orig.) 7 refs.

Carbon nanotube materials for hydrogen storage

Energy Technology Data Exchange (ETDEWEB)

Dillon, A.C.; Parilla, P.A.; Jones, K.M.; Riker, G.; Heben, M.J. [National Renewable Energy Lab., Golden, CO (United States)

1998-08-01

Carbon single-wall nanotubes (SWNTs) are essentially elongated pores of molecular dimensions and are capable of adsorbing hydrogen at relatively high temperatures and low pressures. This behavior is unique to these materials and indicates that SWNTs are the ideal building block for constructing safe, efficient, and high energy density adsorbents for hydrogen storage applications. In past work the authors developed methods for preparing and opening SWNTs, discovered the unique adsorption properties of these new materials, confirmed that hydrogen is stabilized by physical rather than chemical interactions, measured the strength of interaction to be {approximately} 5 times higher than for adsorption on planar graphite, and performed infrared absorption spectroscopy to determine the chemical nature of the surface terminations before, during, and after oxidation. This year the authors have made significant advances in synthesis and characterization of SWNT materials so that they can now prepare gram quantities of high-purity SWNT samples and measure and control the diameter distribution of the tubes by varying key parameters during synthesis. They have also developed methods which purify nanotubes and cut nanotubes into shorter segments. These capabilities provide a means for opening the tubes which were unreactive to the oxidation methods that successfully opened tubes, and offer a path towards organizing nanotube segments to enable high volumetric hydrogen storage densities. They also performed temperature programmed desorption spectroscopy on high purity carbon nanotube material obtained from collaborator Prof. Patrick Bernier and finished construction of a high precision Seivert`s apparatus which will allow the hydrogen pressure-temperature-composition phase diagrams to be evaluated for SWNT materials.

Adsorption and catalytic properties of skeleton nickel alloyed by tantalum

Energy Technology Data Exchange (ETDEWEB)

Erzhanova, M S; Sokol' skii, D V; Popov, N I; Kondratenko, V I

1977-02-01

Adsorption properties are studied of Ni-Ta-catalysts composed of 20-50% Ni, 0-30% Ta, 50% Al with respect to hydrogen; their activity in a number of reactions has been tested. The adsorption capacity is characterized with respect to H/sub 2/ by the methods of thermodesorption and conductometry. It is shown that three forms to hydrogen (..beta.., ..gamma.., sigma) adsorb onto the surface of the alloyed catalysts, whose desorption peaks overlap because of their high mobility and interchangeability. Variation of activity, selectivity and isomerizing capacity of the catalysts correlates with the content of a weakly adsorbed mobile form of H/sub 2/.

Probe measurements of hydrogen fluxes during discharge cleaning in JFT-2M

International Nuclear Information System (INIS)

Matsuzaki, Y.

1989-01-01

Thermal desorption spectroscopy (TDS) has been applied during discharge cleaning in the JFT-2M tokamak to measure hydrogen fluxes. The TDS carbon sample, thickness 0.13 mm, was heated to 1000 0 C by direct current and the temperature distribution of the sample surface measured by infrared thermography. The probe was exposed to three types of plasma: Taylor-type discharge cleaning (TDC), ECR discharge cleaning (ECR-DC), and glow discharge cleaning (GDC). The TDS spectra show peak desorption at around 800 0 C. The hydrogen flux, obtained by integration of the TDS spectrum, decreases exponentially in the radial direction with decay length 7.4 cm and 5.8 cm in TDC and ECR-DC, respectively. The relation between hydrogen fluxes and water vapour production was investigated. In TDC, the amount of water vapour depends more strongly on the electron temperature of the plasma than on the hydrogen flux. In ECR-DC, the production of water vapour increases approximately linearly with the hydrogen-flux. In GDC, hydrogen fluxes were measured by TDS but no water vapour could be detected in the residual gases during the discharge. (orig.)

The Role of Hydrogen-Enhanced Strain-Induced Lattice Defects on Hydrogen Embrittlement Susceptibility of X80 Pipeline Steel

Science.gov (United States)

Hattori, M.; Suzuki, H.; Seko, Y.; Takai, K.

2017-08-01

Studies to date have not completely determined the factors influencing hydrogen embrittlement of ferrite/bainite X80 pipeline steel. Hydrogen embrittlement susceptibility was evaluated based on fracture strain in tensile testing. We conducted a thermal desorption analysis to measure the amount of tracer hydrogen corresponding to that of lattice defects. Hydrogen embrittlement susceptibility and the amount of tracer hydrogen significantly increased with decreasing crosshead speed. Additionally, a significant increase in the formation of hydrogen-enhanced strain-induced lattice defects was observed immediately before the final fracture. In contrast to hydrogen-free specimens, the fracture surface of the hydrogen-charged specimens exhibited shallower dimples without nuclei, such as secondary phase particles. These findings indicate that the presence of hydrogen enhanced the formation of lattice defects, particularly just prior to the occurrence of final fracture. This in turn enhanced the formation of shallower dimples, thereby potentially causing premature fracture of X80 pipeline steel at lower crosshead speeds.

Microporous Metal Organic Materials for Hydrogen Storage

Energy Technology Data Exchange (ETDEWEB)

S. G. Sankar; Jing Li; Karl Johnson

2008-11-30

We have examined a number of Metal Organic Framework Materials for their potential in hydrogen storage applications. Results obtained in this study may, in general, be summarized as follows: (1) We have identified a new family of porous metal organic framework materials with the compositions M (bdc) (ted){sub 0.5}, {l_brace}M = Zn or Co, bdc = biphenyl dicarboxylate and ted = triethylene diamine{r_brace} that adsorb large quantities of hydrogen ({approx}4.6 wt%) at 77 K and a hydrogen pressure of 50 atm. The modeling performed on these materials agree reasonably well with the experimental results. (2) In some instances, such as in Y{sub 2}(sdba){sub 3}, even though the modeling predicted the possibility of hydrogen adsorption (although only small quantities, {approx}1.2 wt%, 77 K, 50 atm. hydrogen), our experiments indicate that the sample does not adsorb any hydrogen. This may be related to the fact that the pores are extremely small or may be attributed to the lack of proper activation process. (3) Some samples such as Zn (tbip) (tbip = 5-tert butyl isophthalate) exhibit hysteresis characteristics in hydrogen sorption between adsorption and desorption runs. Modeling studies on this sample show good agreement with the desorption behavior. It is necessary to conduct additional studies to fully understand this behavior. (4) Molecular simulations have demonstrated the need to enhance the solid-fluid potential of interaction in order to achieve much higher adsorption amounts at room temperature. We speculate that this may be accomplished through incorporation of light transition metals, such as titanium and scandium, into the metal organic framework materials.

Methylamine-hydrogen exchange Part III. Physicochemical properties of amide-amine solutions

International Nuclear Information System (INIS)

Srinivasa, K.; Dave, S.M.

1983-01-01

Different physicochemical properties of potassium methylamide/methylamine solutions have been compiled and reviewed. These properties will be quite useful in design calculations for plants based on amine-hydrogen exchange for the production of heavy water. (author)

Effects of partial hydrogenation, epoxidation, and hydroxylation on the fuel properties of fatty acid methyl esters

Energy Technology Data Exchange (ETDEWEB)

Wadumesthrige, Kapila; Salley, Steven O.; Ng, K.Y. Simon [Department of Chemical Engineering and Materials Science, Wayne State University, 5050 Anthony Wayne Drive, Detroit, MI 48202 (United States)

2009-10-15

The properties of biodiesel depend on the chemical structure of individual fatty acid methyl esters (FAME). In this work the chemical structure of fatty acid chains was modified by catalytic hydrogenation, epoxidation and hydroxylation under controlled conditions. Hydrolysis of ester functionality or oxidation of fatty acid chain was not observed during these reactions. The properties of hydrogenated FAME strongly depend on the hydrogenation time. The total saturated fatty acid (SFA) percentage increased from 29.3% to 76.2% after 2 h of hydrogenation. This hydrogenated FAME showed higher oxidation stability and higher cetane number but poor cold flow properties. Formation of trans FAME was observed during hydrogenation. Both hydroxylation and epoxidation resulted in a decrease of unsaturated fatty acid methyl ester (UFA) fraction. The percentages of total unsaturated FAME decreased 39% in the epoxidation reaction and 44% in the hydroxylation reaction. The addition of hydroxyl groups to the unsaturated regions of the fatty acid chain yields biodiesel with better cold flow properties, increased lubricity and slightly increased oxidative stability. However, epoxy FAME shows some interesting properties such as higher oxidation stability, higher cetane number and acceptable cold flow properties, which met the limits of ASTM D6751 biodiesel specifications. (author)

Hydrogen trapping in and release from tungsten: modeling and comparison with graphite with regard to its use as fusion reactor material

International Nuclear Information System (INIS)

Franzen, P.; Garcia-Rosales, C.; Plank, H.; Alimov, V.Kh.

1997-01-01

Trapping and release of deuterium implanted in tungsten is investigated by modeling the results of reemission, thermal and isothermal desorption experiments. Rate coefficients and activation energies for diffusion, trapping and detrapping are derived. Hydrogen atoms are able to diffuse deep into tungsten, establishing a solute amount of the same order of magnitude as the trapped one. This 'diffusion zone' exceeds the implantation zone by more than two orders of magnitude, even at room temperature. The solute amount of hydrogen in tungsten depends only slightly on the incident ion energy, but scales with implantation fluence. This high amount of solute hydrogen is the main difference of tungsten compared to graphite where nearly all hydrogen is trapped in the implantation zone, the solute amount being orders of magnitude lower. The resulting unlimited accumulation of hydrogen in tungsten deep in the material down to the backward surface disadvantages tungsten as fusion reactor material with regard to hydrogen recycling properties. (orig.)

Investigations on ion-beam induced desorption from cryogenic surfaces; Untersuchungen zu ionenstrahlinduzierter Desorption von kryogenen Oberflaechen

Energy Technology Data Exchange (ETDEWEB)

Maurer, Christoph

2017-07-03

pumps can be taken into account. This method can be extended to any desorption experiment employing the single shot method for measurement. Of special interest for the operation of the SIS100 at high intensities is the minimization of desorption from cryogenic surfaces. A previous examination of this topic found a breakdown of the familiar scaling of the desorption yield with the beam's energy loss for cryogenic targets. Further examination of this effect with the techniques described above is another goal of this thesis. Simultaneously, desorption measurements at room temperature for several other targets have been conducted. An unexpected result of these experiments is the influence of target surface properties, which was found to be very weak in comparison to previous results. The methods developed during this thesis, along with the results gained by their application, represent another step towards the comprehension of (heavy) ion beam induced desorption.

"Job-Sharing" Storage of Hydrogen in Ru/Li₂O Nanocomposites.

Science.gov (United States)

Fu, Lijun; Tang, Kun; Oh, Hyunchul; Manickam, Kandavel; Bräuniger, Thomas; Chandran, C Vinod; Menzel, Alexander; Hirscher, Michael; Samuelis, Dominik; Maier, Joachim

2015-06-10

A "job-sharing" hydrogen storage mechanism is proposed and experimentally investigated in Ru/Li2O nanocomposites in which H(+) is accommodated on the Li2O side, while H(-) or e(-) is stored on the side of Ru. Thermal desorption-mass spectroscopy results show that after loading with D2, Ru/Li2O exhibits an extra desorption peak, which is in contrast to Ru nanoparticles or ball-milled Li2O alone, indicating a synergistic hydrogen storage effect due to the presence of both phases. By varying the ratio of the two phases, it is shown that the effect increases monotonically with the area of the heterojunctions, indicating interface related hydrogen storage. X-ray diffraction, Fourier transform infrared spectroscopy, and nuclear magnetic resonance results show that a weak LiO···D bond is formed after loading in Ru/Li2O nanocomposites with D2. The storage-pressure curve seems to favor H(+)/H(-) over H(+)/e(-) mechanism.

Interaction of hydrogen and oxygen with continuous or granular films of palladium

Energy Technology Data Exchange (ETDEWEB)

Mikhalenko, I.I.; Prokopov, A.M.; Yagodovskii, V.D.

1986-03-01

The authors use desorption and conductometric methods in establishing the existence of three species of adsorbed hydrogen on continuous Pd films and two species on Pd films with a granular structure. Preoxidation of the surface of the continuous films does not affect the rate or kinetic order of hydrogen sorption; oxidation/reduction treatment changes these parameters, but the magnitude of Edes of hydrogen remains unchanged.

Modelling for Near-Surface Transport Dynamics of Hydrogen of Plasma Facing Materials by use of Cellular Automaton

International Nuclear Information System (INIS)

Shimura, K.; Terai, T.; Yamawaki, M.

2003-01-01

In this study, the kinetics of desorption of adsorbed hydrogen from an ideal metallic surface is modelled in Cellular Automaton (CA). The modelling is achieved by downgrading the surface to one dimension. The model consists of two parts that are surface migration and desorption. The former is attained by randomly sorting the particles at each time, the latter is realised by modelling the thermally-activated process. For the verification of this model, thermal desorption is simulated then the comparison with the chemical kinetics is carried out. Excellent agreement is observed from the result. The results show that this model is reasonable to express the recombinative desorption of two chemisorbed adatoms. Though, the application of this model is limited to the second-order reaction case. But it can be believed that the groundwork of modelling the transport dynamics of hydrogen through the surface under complex conditions is established

Dependence of hydrogen storage characteristics of mechanically milled carbon materials on their host structures

International Nuclear Information System (INIS)

Shindo, K.; Kondo, T.; Sakurai, Y.

2004-01-01

We investigated whether the hydrogen storage characteristics of carbon materials prepared by mechanical milling in an H 2 atmosphere were dependent on their host structures. We used natural graphite (NG) and activated carbon fibers (ACF) and compared them with activated carbon (AC) powders. The XRD patterns of NG and ACF milled for over 20 h and SEM images of these samples milled for 80 h were almost the same as those of AC. The hydrogen storage capacities of NG and ACF estimated by the inert gas fusion-thermal conductivity method increased with the mechanical milling time up to 10 h and showed little milling time dependence thereafter. The capacities of NG and ACF reached about 3.0 wt.% and were similar to that of AC. However, it should be noted that the hydrogen storage mechanism of NG and ACF mechanically milled in an H 2 atmosphere might be different because the changes in their specific surface areas with milling time were opposite. Thermal desorption mass spectroscopy (TDS) revealed that the desorption spectra of the hydrogen molecules (mass number=2) of NG and ACF milled for 10 h in the same way as AC contained two peaks at about 500 and 800 deg. C. The desorption activation energies of hydrogenated NG and ACF at these peaks calculated from a Kissinger plot were almost with the same as those of hydrogenated AC. This suggests that the state of the hydrogen trapped in the structural defects in NG introduced by the mechanical milling may be almost the same as that of AC. In addition, we assumed the possibility that the state of the hydrogen in ACF hydrogenated by mechanical milling could be almost the same as that in hydrogenated AC. We considered that the nanocarbon materials hydrogenated under our milling conditions had very similar physical shapes and hydrogen storage capacities, independent of their host structures

Modeling of hydrogen/deuterium dynamics and heat generation on palladium nanoparticles for hydrogen storage and solid-state nuclear fusion.

Science.gov (United States)

Tanabe, Katsuaki

2016-01-01

We modeled the dynamics of hydrogen and deuterium adsorbed on palladium nanoparticles including the heat generation induced by the chemical adsorption and desorption, as well as palladium-catalyzed reactions. Our calculations based on the proposed model reproduce the experimental time-evolution of pressure and temperature with a single set of fitting parameters for hydrogen and deuterium injection. The model we generated with a highly generalized set of formulations can be applied for any combination of a gas species and a catalytic adsorbent/absorbent. Our model can be used as a basis for future research into hydrogen storage and solid-state nuclear fusion technologies.

Hydrogen Storage using Metal Hydrides in a Stationary Cogeneration System

International Nuclear Information System (INIS)

Botzung, Maxime; Chaudourne, Serge; Perret, Christian; Latroche, Michel; Percheron-Guegan, Annick; Marty Philippe

2006-01-01

In the frame of the development of a hydrogen production and storage unit to supply a 40 kW stationary fuel cell, a metal hydride storage tank was chosen according to its reliability and high energetic efficiency. The study of AB5 compounds led to the development of a composition adapted to the project needs. The absorption/desorption pressures of the hydride at 75 C (2 / 1.85 bar) are the most adapted to the specifications. The reversible storage capacity (0.95 %wt) has been optimized to our work conditions and chemical kinetics is fast. The design of the Combined Heat and Power CHP system requires 5 kg hydrogen storage but in a first phase, only a 0.1 kg prototype has been realised and tested. Rectangular design has been chosen to obtain good compactness with an integrated plate fin type heat exchanger designed to reach high absorption/desorption rates. In this paper, heat and mass transfer characteristics of the Metal Hydride tank (MH tank) during absorption/desorption cycles are given. (authors)

Formation of H- ions via vibrational excited molecules produced from recombinative wall desorption of H atoms in a low-pressure H/sub 2/ positive column

NARCIS (Netherlands)

Amorim, J.; Loureiro, J.; Schram, D.C.

2001-01-01

Recombinative wall desorption of hydrogen atoms in a low-pressure hydrogen positive column leading to formation of H/sub 2/ (X/sup 1/ Sigma /sub g//sup +/, v) molecules in optimum levels for H/sup -/ production by dissociative attachment is investigated. We employed a kinetic model that solves the

A study on hydrogen adsorption behaviors of open-tip carbon nanocones

International Nuclear Information System (INIS)

Liao Mingliang

2012-01-01

Hydrogen adsorption behaviors of single-walled open-tip (tip-truncated) carbon nanocones (CNCs) with apex angles of 19.2° at temperatures of 77 and 300 K were investigated by the molecular dynamics simulations. Four nanomaterials (including three CNCs with different dimensions and a reference CNT) were analyzed to examine the hydrogen adsorption behaviors and influences of cone sharpness on the behaviors of the CNCs. Physisorption of hydrogen molecules could be observed from the distribution pattern of the hydrogen molecules adsorbed on the nanomaterials. Because of the cone geometry effect, the open-tip CNCs could have larger storage weight percentage and less desorption of hydrogen molecules (caused by the temperature growth) on their outer surfaces, as compared with those of the reference CNT. The hydrogen molecules inside the CNCs and the reference CNT, however, were noted to have similar desorption behaviors owing to the confinement effects from the structures of the nanomaterials. In addition, the sharper CNC could have higher storage weight percentage but the cone sharpness does not have evident enhancement in the average adsorption energy of the CNC. Combination of confinement and repulsion effects existing near the tip region of the CNC would be responsible for the non-enhancement feature.

Ground state structures and properties of small hydrogenated silicon

Indian Academy of Sciences (India)

Unknown

To understand the structural evolutions and properties of silicon cluster due to hydrogenation ... partly due to the growing importance of these systems in applications like .... of the system. Using the Lagrangian (1), equations of motions for the.

Hydrogen energy in changing environmental scenario: Indian context

International Nuclear Information System (INIS)

Leo Hudson, M. Sterlin; Dubey, P.K.; Pukazhselvan, D.; Pandey, Sunil Kumar; Singh, Rajesh Kumar; Raghubanshi, Himanshu; Shahi, Rohit R.; Srivastava, O.N.

2009-01-01

This paper deals with how the Hydrogen Energy may play a crucial role in taking care of the environmental scenario/climate change. The R and D efforts, at the Hydrogen Energy Center, Banaras Hindu University have been described and discussed to elucidate that hydrogen is the best option for taking care of the environmental/climate changes. All three important ingredients for hydrogen economy, i.e., production, storage and application of hydrogen have been dealt with. As regards hydrogen production, solar routes consisting of photoelectrochemical electrolysis of water have been described and discussed. Nanostructured TiO 2 films used as photoanodes have been synthesized through hydrolysis of Ti[OCH(CH 3 ) 2 ] 4 . Modular designs of TiO 2 photoelectrode-based PEC cells have been fabricated to get high hydrogen production rate (∝10.35 lh -1 m -2 ). However, hydrogen storage is a key issue in the success and realization of hydrogen technology and economy. Metal hydrides are the promising candidates due to their safety advantage with high volume efficient storage capacity for on-board applications. As regards storage, we have discussed the storage of hydrogen in intermetallics as well as lightweight complex hydride systems. For intermetallic systems, we have dealt with material tailoring of LaNi 5 through Fe substitution. The La(Ni l-x Fe x ) 5 (x = 0.16) has been found to yield a high storage capacity of ∝2.40 wt%. We have also discussed how CNT admixing helps to improve the hydrogen desorption rate of NaAlH 4 . CNT (8 mol%) admixed NaAlH 4 is found to be optimum for faster desorption (∝3.3 wt% H 2 within 2 h). From an applications point of view, we have focused on the use of hydrogen (stored in intermetallic La-Ni-Fe system) as fuel for Internal Combustion (IC) engine-based vehicular transport, particularly two and three-wheelers. It is shown that hydrogen used as a fuel is the most effective alternative fuel for circumventing climate change. (author)

Sorption-desorption dynamics of radiocaesium in organic matter soils

International Nuclear Information System (INIS)

Valcke, E.; Cremers, A.

1994-01-01

A systematic study has been carried out on the radiocaesium sorption properties of 25 soils (forest, peat) covering organic matter (OM) contents in the range of 10-97%. Predictions are made for radiocaesium partitioning between micaceous Frayed Edge Sites (FES) and regular exchange sites (RES) on the basis of specific radiocaesium interception potentials of the soil and overall exchange capacity. It is shown that for soils with a very high OM content (>80%), significant fractions are present in a readily reversible form in the OM phase. In soils of low-medium OM content (<40%), only a very minor fraction is present in the OM exchange complex. Experimental findings, based on a desorption screening with a variety of desorption agents are in agreement with these predictions. On the basis of a study of sorption kinetics, some additional tools are available for identifying problem soils. In cases of very high OM content, radiocaesium adsorption is completed within hours demonstrating the involvement of the OM sites. In soils for which interception occurs in the FES, sorption continues to proceed for periods of 2-3 weeks. In conclusion, some examples are presented on radiocaesium desorption using ion exchangers as radiocaesium sinks in promoting desorption. For a peaty soil, near quantitative desorption is accomplished. For forest soils with OM contents in a range of 10-40%, fixation levels of 30-50% are demonstrated

Modelling of Convective Process of Water Desorption from Polystyrene

International Nuclear Information System (INIS)

Stakic, M.; Nikolic, A.

2008-01-01

This study presents a mathematical model developed to evaluate the influence of structural and operational factors on convective dehydration process (desorption of liquid phase from capillary-porous material), as well as the possibility to utilize this model for the case of water desorption from polystyrene cation resin CG-8. The model accounts for unsteady one-dimensional simultaneous heat and mass transfer between the gas (air) and the solid phase (resin). The identification of effective transport properties for the considered fixed bed of material (resin CG 8) is discussed. To this purpose available data from the literature are used. (author)

Oxygen- and Lithium-Doped Hybrid Boron-Nitride/Carbon Networks for Hydrogen Storage.

Science.gov (United States)

Shayeganfar, Farzaneh; Shahsavari, Rouzbeh

2016-12-20

Hydrogen storage capacities have been studied on newly designed three-dimensional pillared boron nitride (PBN) and pillared graphene boron nitride (PGBN). We propose these novel materials based on the covalent connection of BNNTs and graphene sheets, which enhance the surface and free volume for storage within the nanomaterial and increase the gravimetric and volumetric hydrogen uptake capacities. Density functional theory and molecular dynamics simulations show that these lithium- and oxygen-doped pillared structures have improved gravimetric and volumetric hydrogen capacities at room temperature, with values on the order of 9.1-11.6 wt % and 40-60 g/L. Our findings demonstrate that the gravimetric uptake of oxygen- and lithium-doped PBN and PGBN has significantly enhanced the hydrogen sorption and desorption. Calculations for O-doped PGBN yield gravimetric hydrogen uptake capacities greater than 11.6 wt % at room temperature. This increased value is attributed to the pillared morphology, which improves the mechanical properties and increases porosity, as well as the high binding energy between oxygen and GBN. Our results suggest that hybrid carbon/BNNT nanostructures are an excellent candidate for hydrogen storage, owing to the combination of the electron mobility of graphene and the polarized nature of BN at heterojunctions, which enhances the uptake capacity, providing ample opportunities to further tune this hybrid material for efficient hydrogen storage.

Hydrogen induced surface effects on the mechanical properties of type 304 stainless steel

International Nuclear Information System (INIS)

Silva, T.C.V. da; Pascual, R.; Miranda, P.E.V. de.

1983-01-01

The possibilities of modifying the mechanical properties of type 304 stainless steel by cathodic hydrogen charging were studied. The situations analysed included hydrogen embrittlement itself in tensile tests of hydrogen containing samples and the effects of delayed cracks in fatigue tests of hydrogenated and outgassed samples. SEM and TEM observations were also performed. It was found that hydrogen induced surface delayed cracks appear in great quantity during outgassing (of the order of several millions in a square centimeter). Hydrogen embrittlement was responsible for drastic losses in ductility in tension, while surface cracks severely reduced fatigue life. (author) [pt

The effect of atomic hydrogen adsorption on single-walled carbon nano tubes properties

International Nuclear Information System (INIS)

Jalili, S.; Majidi, R.

2007-01-01

We investigated the adsorption of hydrogen atoms on metallic single-walled carbon nano tubes using ab initio molecular dynamics method. It was found that the geometric structures and the electronic properties of hydrogenated SWNTs can be strongly changed by varying hydrogen coverage. The circular cross sections of the CNTs were changed with different hydrogen coverage. When hydrogen is chemisorbed on the surface of the carbon nano tube, the energy gap will be appeared. This is due to the degree of the Sp 3 hybridization, and the hydrogen coverage can control the band gap of the carbon nano tube

Carbon compound used in hydrogen storage

International Nuclear Information System (INIS)

Iturbe G, J.L.; Lopez M, B.E.

2004-01-01

In the present work it is studied the activated carbon of mineral origin for the sorption of hydrogen. The carbon decreased of particle size by means of the one alloyed mechanical. The time of mill was of 10 hours. The characterization one carries out by scanning electron microscopy and X-ray diffraction. The hydrogen sipped in the carbon material it was determined using the Thermal gravimetric method (TGA). The conditions of hydrogenation went at 10 atm of pressure and ambient temperature during 18 hours. They were also carried out absorption/desorption cycles of hydrogen in the same one system of thermal gravimetric analysis. The results showed percentages of sorption of 2% approximately in the cycles carried out in the system TGA and of 4.5% in weight of hydrogen at pressure of 10 atmospheres and ambient temperature during 18 hours. (Author)

Hydrogenated amorphous carbon next deposit after heat treatment

International Nuclear Information System (INIS)

Salancon, E.; Durbeck, T.; Schwarz-Selinger, T.; Jacob, W.

2006-01-01

One of the main safety problems in the ITER tokamak project is the tritium adsorption in the reactor walls and in particular the deposits which appear after the plasma discharge. These deposits are amorphous hydrogenated carbon films, type polymer (soft a-C:H). The heating of these deposits with a pulse laser is a proposed solution for the tritium desorption. Meanwhile, Gibson and al show that in experimental conditions, products are deposed on the walls before entering the mass spectrometer. The authors present thermo-desorption spectra of different amorphous carbon films. (A.L.B.)

Thermal Effect on the Structural, Electrical, and Optical Properties of In-Line Sputtered Aluminum Doped Zinc Oxide Films Explored with Thermal Desorption Spectroscopy

Directory of Open Access Journals (Sweden)

Shang-Chou Chang

2014-01-01

Full Text Available This work investigates the thermal effect on the structural, electrical, and optical properties of aluminum doped zinc oxide (AZO films. The AZO films deposited at different temperatures were measured using a thermal desorption system to obtain their corresponding thermal desorption spectroscopy (TDS. In addition to obtaining information of thermal desorption, the measurement of TDS also has the effect of vacuum annealing on the AZO films. The results of measuring TDS imply part of the doped aluminum atoms do not stay at substituted zinc sites in AZO films. The (002 preferential direction of the AZO films in X-ray diffraction spectra shifts to a lower angle after measurement of TDS. The grain size grows and surface becomes denser for all AZO films after measurement of TDS. The carrier concentration, mobility, and average optical transmittance increase while the electrical resistivity decreases for AZO films after measurement of TDS. These results indicate that the AZO films deposited at 200°C are appropriate selections if the AZO films are applied in device fabrication of heat-produced process.

Influence of fillers on hydrogen penetration properties and blister fracture of rubber composites for O-ring exposed to high-pressure hydrogen gas

Energy Technology Data Exchange (ETDEWEB)

Yamabe, Junichiro; Nishimura, Shin [Department of Mechanical Science Engineering, Kyushu University, 744 Motooka, Nishi-ku, Fukuoka 819-0395 (Japan); Research Center for Hydrogen Industrial Use and Storage (HYDROGENIUS), National Institute of Advanced Industrial Science and Technology (AIST), 744 Motooka, Nishi-ku, Fukuoka 819-0395 (Japan)

2009-02-15

Ethylene-propylene rubber (EPDM) and nitrile-butadiene rubber (NBR) composites having carbon black, silica, and no fillers were exposed to hydrogen gas at a maximum pressure of 10 MPa; then, blister tests and the measurement of hydrogen content were conducted. The hydrogen contents of the composites were proportional to the hydrogen pressure, i.e., the behavior of their hydrogen contents follows Henry's law. This implies that hydrogen penetrates into the composite as a hydrogen molecule. The addition of carbon black raised the hydrogen content of the composite, while the addition of silica did not. Based on observations, the blister damages of composites with silica were less pronounced, irrespective of the hydrogen pressures. This may be attributed to their lower hydrogen content and relatively better tensile properties than the others. (author)

Electrical properties and flux performance of composite ceramic hydrogen separation membranes

DEFF Research Database (Denmark)

Fish, J.S.; Ricote, Sandrine; O'Hayre, R.

2015-01-01

The electrical properties and hydrogen permeation flux behavior of the all-ceramic protonic/electronic conductor composite BaCe0.2Zr0.7Y0.1O3-δ/Sr0.95Ti0.9Nb0.1O3-δ (BCZY27/STN95: BS27) are evaluated. Conductivity and hydrogen permeability are examined as a function of phase volume ratios. Total ...

Instrumented impact properties of zircaloy-oxygen and zircaloy-hydrogen alloys

Energy Technology Data Exchange (ETDEWEB)

Garde, A.M.; Kassner, T.F.

1980-04-01

Instrumented-impact tests were performed on subsize Charpy speciments of Zircaloy-2 and -4 with up to approx. 1.3 wt % oxygen and approx. 2500 wt ppM hydrogen at temperatures between 373 and 823/sup 0/K. Self-consistent criteria for the ductile-to-brittle transition, based upon a total absorbed energy of approx. 1.3 x 10/sup 4/ J/m/sup 2/, a dynamic fracture toughness of approx. 10 MPa.m/sup 1/2/, and a ductility index of approx. 0, were established relative to the temperature and oxygen concentration of the transformed BETA-phase material. The effect of hydrogen concentration and hydride morphology, produced by cooling Zircaloy-2 specimens through the temperature range of the BETA ..-->.. ..cap alpha..' = hydride phase transformation at approx. 0.3 and 3 K/s, on the impact properties was determined at temperatures between 373 and 673 K. On an atom fraction basis, oxygen has a greater effect than hydrogen on the impact properties of Zircaloy at temperatures between approx. 400 and 600 K. 34 figures.

Hydrogen in trapping states innocuous to environmental degradation of high-strength steels

International Nuclear Information System (INIS)

Takai, Kenichi

2003-01-01

Hydrogen in trapping states innocuous to environmental degradation of the mechanical properties of high-strength steels has been separated and extracted using thermal desorption analysis (TDA) and slow strain rate test (SSRT). The high-strength steel occluding only hydrogen desorbed at low temperature (peak 1), as determined by TDA, decreases in maximum stress and plastic elongation with increasing occlusion time of peak 1 hydrogen. Thus the trapping state of peak 1 hydrogen is directly associated with environmental degradation. The trap activation energy for peak 1 hydrogen is 23.4 kJ/mol, so the peak 1 hydrogen corresponds to weaker binding states and diffusible states at room temperature. In contrast, the high-strength steel occluding only hydrogen desorbed at high temperature (peak 2), by TDA, maintains the maximum stress and plastic elongation in spite of an increasing content of peak 2 hydrogen. This result indicates that the peak 2 hydrogen trapping state is innocuous to environmental degradation, even though the steel occludes a large amount of peak 2 hydrogen. The trap activation energy for peak 2 hydrogen is 65.0 kJ/mol, which indicates a stronger binding state and nondiffusibility at room temperature. The trap activation energy for peak 2 hydrogen suggests that the driving force energy required for stress-induced, diffusion during elastic and plastic deformation, and the energy required for hydrogen dragging by dislocation mobility during plastic deformation are lower than the binding energy between hydrogen and trapping sites. The peak 2 hydrogen, therefore, is believed to not accumulate in front of the crack tip and to not cause environmental degradation in spite of being present in amounts as high as 2.9 mass ppm. (author)

Bile salts at the air-water interface: adsorption and desorption.

Science.gov (United States)

Maldonado-Valderrama, J; Muros-Cobos, J L; Holgado-Terriza, J A; Cabrerizo-Vílchez, M A

2014-08-01

Bile salts (BS) are bio-surfactants which constitute a vital component in the process of fat digestion. Despite the importance of the interfacial properties in their biological role, these have been scarcely studied in the literature. In this work, we present the adsorption-desorption profiles of two BS (NaTC and NaGDC) including dilatational rheology. Findings from this study reveal very different surface properties of NaTC and NaGDC which originate from different complexation properties relevant to the digestion process. Dynamic adsorption curves show higher adsorption rates for NaTC and suggest the existence of various conformational regimes in contrast to NaGDC which presents only one conformational regime. This is corroborated by analysis of the adsorption isotherms and more in detail by the rheological behaviour. Accordingly, the dilatational response at 1Hz displays two maxima of the dilatational modulus for NaTC as a function of bulk concentration, in contrast to NaGDC which displays only one maximum. The desorption profiles reveal that NaTC adopts an irreversibly adsorbed form at high surface coverage whereas NaGDC fully desorbs from the surface within the whole range of concentrations used. Analysis of the adsorption-desorption profiles provides new insight into the surface properties of BS, suggesting a surface complexation of NaTC. This knowledge can be useful since through interfacial engineering we might control the extent of lipolysis providing the basis for the rational design of food products with tailored digestibility. Copyright © 2014 Elsevier B.V. All rights reserved.

Effects of External Hydrogen on Hydrogen Transportation and Distribution Around the Fatigue Crack Tip in Type 304 Stainless Steel

Science.gov (United States)

Chen, Xingyang; Zhou, Chengshuang; Cai, Xiao; Zheng, Jinyang; Zhang, Lin

2017-10-01

The effects of external hydrogen on hydrogen transportation and distribution around the fatigue crack tip in type 304 stainless steel were investigated by using hydrogen microprint technique (HMT) and thermal desorption spectrometry. HMT results show that some silver particles induced by hydrogen release are located near the fatigue crack and more silver particles are concentrated around the crack tip, which indicates that hydrogen accumulates in the vicinity of the crack tip during the crack growth in hydrogen gas environment. Along with the crack propagation, strain-induced α' martensite forms around the crack tip and promotes hydrogen invasion into the matrix, which will cause the crack initiation and propagation at the austenite/ α' martensite interface. In addition, the hydrogen content in the vicinity of the crack tip is higher than that at the crack edge far away from the crack tip, which is related to the stress state and strain-induced α' martensite.

Hydrogen storage by functionalised Poly(ether ether ketone)

Energy Technology Data Exchange (ETDEWEB)

Pedicini, R.; Giacoppo, G.; Carbone, A.; Passalacqua, E. [CNR-ITAE, Messina (Italy). Inst. for Advanced Energy Technologies

2010-07-01

In this work a functionalised polymer was studied as potential material for hydrogen storage in solid state. A Poly(ether ether ketone) (PEEK) matrix was modified by a manganese oxide in situ formation. Here we report the functionalisation process and the preliminary results on hydrogen storage capability of the synthesised polymer. The polymer was characterized by Scanning Electron Microscopy, X-ray diffraction, Transmission Electron Microscopy and Gravimetric Hydrogen Adsorption measurements. In the functionalised PEEK, morphological changes occur as a function of oxide precursor concentration and reaction time. Promising results by gravimetric measurements were obtained with a hydrogen sorption of 0.24%wt/wt at 50 C and 60 bar, moreover, reversibility hydrogen adsorption and desorption in a wide range of both temperature and pressure was confirmed. (orig.)

Carbon tetrachloride desorption from activated carbon

International Nuclear Information System (INIS)

Jonas, L.A.; Sansone, E.B.

1981-01-01

Carbon tetrachloride was desorbed from a granular activated carbon subsequent to its adsorption under various vapor exposure periods. The varied conditions of exposure resulted in a range of partially saturated carbon beds which, when followed by a constant flow rate for desorption, generated different forms of the desorbing concentration versus time curve. A method of analyzing the desorption curves is presented which permits extraction of the various desorbing rates from the different desorption and to relate this to the time required for such regeneration. The Wheeler desorption kinetic equation was used to calculate the pseudo first order desorption rate constant for the carbon. The desorption rate constant was found to increase monotonically with increasing saturation of the bed, permitting the calculation of the maximum desorption rate constant for the carbon at 100% saturation. The Retentivity Index of the carbon, defined as the dimensionless ratio of the adsorption to the desorption rate constant, was found to be 681

Sorption of nitrate onto amine-crosslinked wheat straw: characteristics, column sorption and desorption properties.

Science.gov (United States)

Xing, Xu; Gao, Bao-Yu; Zhong, Qian-Qian; Yue, Qin-Yan; Li, Qian

2011-02-15

The nitrate removal process was evaluated using a fixed-bed column packed with amine-crosslinked wheat straw (AC-WS). Column sorption and desorption characteristics of nitrate were studied extensively. Solid-state (13)C NMR and zeta potential analysis validated the existence of crosslinked amine groups in AC-WS. Raman shift of the nitrate peaks suggested the electrostatic attraction between the adsorbed ions and positively charged amine sites. The column sorption capacity (q(ed)) of the AC-WS for nitrate was 87.27 mg g(-1) in comparison with the raw WS of 0.57 mg g(-1). Nitrate sorption in column was affected by bed height, influent nitrate concentration, flow rate and pH, and of all these, influent pH demonstrated an essential effect on the performance of the column. In addition, desorption and dynamic elution tests were repeated for several cycles, with high desorption rate and slight losses in its initial column sorption capacity. Copyright © 2010 Elsevier B.V. All rights reserved.

Thermally-driven hydrogen interaction with single-layer graphene on SiO2/Si substrates

International Nuclear Information System (INIS)

Feijo, Tais Orestes; Rolim, Guilherme Koszeniewski; Radtke, Claudio; Soares, Gabriel Vieira

2016-01-01

Full text: Graphene is a monolayer of carbon with sp 2 hybridization and hexagonal structure. Since all its area is exposed to the atmosphere, it is important to understand how graphene interacts with elements present in the atmosphere, such as hydrogen, oxygen and water, to control the processes of manufacturing [1]. In addition, some studies show that graphene can allow storage of hydrogen for use in fuel cells, which would contribute to the use of clean energies. This study aims to understand the thermally-driven hydrogen interaction with graphene samples. We used samples of graphene deposited on SiO 2 (285 nm) films on Si and then annealed in controlled atmosphere of deuterium (D 2 , natural abundance of 0.15%) at temperatures between 200 and 1000°C. We also investigated hydrogen desorption from graphene using samples previously treated in deuterium at 600°C and afterwards annealed in nitrogen atmosphere between 200 and 1000°C. After annealings, Nuclear Reaction Analysis (NRA) was employed to quantify deuterium, where we observed a large increase in deuterium incorporation above 400°C, with an constant D incorporation until 1000°C. We also observed that the desorption of deuterium from graphene only occurred above 800°C, although D desorption from silicon oxide samples takes place already at 600°C. Raman spectroscopy analysis was performed after each thermal treatment. Results show that defects in the graphene structure increases for higher treatment temperatures in incorporation and in desorption steps. Characterization using X-Ray Photoelectron Spectroscopy (XPS) and Near Edge X-ray Absorption Fine Structure (NEXAFS) will also be presented. [1] A. C. Ferrari, et al., Nanoscale 7 (2015). (author)

Investigation of microstructure changes in ODS-EUROFER after hydrogen loading

International Nuclear Information System (INIS)

Emelyanova, O.V.; Ganchenkova, M.G.; Malitskii, E.; Yagodzinskyy, Y.N.; Klimenkov, M.; Borodin, V.A.; Vladimirov, P.V.; Lindau, R.; Möslang, A.; Hänninen, H.

2016-01-01

The effect of hydrogen on the microstructure of mechanically tested ODS-EUROFER steel was investigated by means of transmission electron microscopy, thermal desorption spectroscopy, and atomistic simulations. The presence of yttrium oxide particles notably increases hydrogen uptake in ODS-EUROFER steel as compared to ODS-free EUROFER 97. Under tensile loading, hydrogen accumulation promotes the loss of cohesion at the oxide particle interfaces. First-principles molecular dynamics simulations indicate that hydrogen can be trapped at nanoparticle/matrix interface, creating OH-groups. The accumulation of hydrogen atoms at the oxide particle surface can be the reason for the observed hydrogen-induced oxide/matrix interface weakening and de-cohesion under the action of external tensile stress.

Hydrogenation properties of pure magnesium and magnesium-aluminium thin films

Energy Technology Data Exchange (ETDEWEB)

Domenech-Ferrer, Roger; Gurusamy Sridharan, Madana; Garcia, Gemma; Pi, Francesc; Rodriguez-Viejo, Javier [Departament de Fisica, Universitat Autonoma de Barcelona, 08193 Bellaterra (Spain)

2007-06-10

We have studied the hydrogenation/dehydrogenation behaviour of multilayered stacks of Pd/Mg/Pd and Pd-Fe(Ti)-Mg-Al-Mg-Fe(Ti)-Pd grown by electron beam physical vapour deposition. The palladium coating was deposited at both sides of the structure to ensure a fast dissociation rate and good transport properties for hydrogen as well as to avoid oxidation of magnesium either from atmosphere as from the substrate surface. Fe and Ti layers were included in the stack composition in order to assess their possible catalyst effect as well as to prevent the formation of Mg{sub x}Pd{sub y} intermetallics during the thermal treatments. We have studied the structure evolution after thermal treatments as well as after the hydrogenation and dehydrogenation processes using XRD. We have also followed the reactions kinetics by resistometry and differential scanning calorimetry. The nanostructured Mg films have been hydrogenated at temperature as low as 50 C in few minutes. Adding aluminium to magnesium has improved its hydrogenation capacity. We have also observed that the formation of an Mg{sub x}Al{sub y} intermetallic before hydrogenation improves the storage capacity. We have confirmed that titanium is a better catalyst for the hydrogenation/dehydrogenation of the Mg films. (author)

Ultra-fast photo-patterning of hydroxamic acid layers adsorbed on TiAlN: The challenge of modeling thermally induced desorption

Energy Technology Data Exchange (ETDEWEB)

Hemgesberg, Maximilian [Fachbereich Chemie, Technische Universitaet Kaiserslautern, Erwin-Schroedinger-Strasse 54, 67663 Kaiserslautern (Germany); Schuetz, Simon [Fachbereich Physik und Forschungszentrum OPTIMAS, Technische Universitaet Kaiserslautern, Erwin-Schroedinger-Strasse 45, 67663 Kaiserslautern (Germany); Heidelberger Druckmaschinen AG, Kurfuerstenanlage 54-60, 66120 Heidelberg (Germany); Mueller, Christine [Fachbereich Physik und Forschungszentrum OPTIMAS, Technische Universitaet Kaiserslautern, Erwin-Schroedinger-Strasse 45, 67663 Kaiserslautern (Germany); Schloerholz, Matthias; Latzel, Harald [Heidelberger Druckmaschinen AG, Kurfuerstenanlage 54-60, 66120 Heidelberg (Germany); Sun, Yu [Fachbereich Chemie, Technische Universitaet Kaiserslautern, Erwin-Schroedinger-Strasse 54, 67663 Kaiserslautern (Germany); Ziegler, Christiane [Fachbereich Physik und Forschungszentrum OPTIMAS, Technische Universitaet Kaiserslautern, Erwin-Schroedinger-Strasse 45, 67663 Kaiserslautern (Germany); Thiel, Werner R., E-mail: thiel@chemie.uni-kl.de [Fachbereich Chemie, Technische Universitaet Kaiserslautern, Erwin-Schroedinger-Strasse 54, 67663 Kaiserslautern (Germany)

2012-10-15

Highlights: Black-Right-Pointing-Pointer Different hydroxamic acids are suitable for the hydrophobization of TiAlN surfaces used in photo-patterning applications. Black-Right-Pointing-Pointer The binding strength of the surfactant on the surface is dependent on the hydrogen and {pi}-bonding interactions within the organic layer. Black-Right-Pointing-Pointer Thermal desorption of selected HA species results in a 20% energy reduction compared to alkyl phosphates. - Abstract: Long-chain n-alkyl terminated hydroxamic acids (HA) are used for the modification of titanium aluminum nitride (TiAlN) surfaces. HA coatings improve the hydrophobicity of this wear resistant and industrially relevant ceramic. Therefore, HAs with different structural properties are evaluated with respect to their wear resistance and their thermal desorption properties. In order to find new coatings for rewritable offset printing plates, the changes in the surface polarity, composition, and morphology are analyzed by contact angle measurements, X-ray photoemission spectroscopy (XPS), and scanning force microscopy (SFM), respectively. The results are referenced to the strongly bonding molecule n-dodecyl phosphonate (PO11M), which has been used for surface hydrophobization before but proved difficult to remove due to the high laser outputs required for thermal desorption. It is found that for certain HAs, an equally good hydrophobization compared to PO11M can be achieved. Contact angles obtained for different hydroxamic acid coatings can be correlated to their modes of adsorption. Only for selected HA species, resistance to mechanical wear is sufficient for further investigations. Photo-patterning of these hydroxamic acid layers is achieved using a high energy IR laser beam at different energy inputs. Fitting of the obtained data and further evaluation using finite element analysis (FEM) calculations reveal significantly reduced energy consumption of about 20% for the removal of a specific hydroxamic

Modelling of hydrogen permeability of membranes for high-purity hydrogen production

Science.gov (United States)

Zaika, Yury V.; Rodchenkova, Natalia I.

2017-11-01

High-purity hydrogen is required for clean energy and a variety of chemical technology processes. Different alloys, which may be well-suited for use in gas-separation plants, were investigated by measuring specific hydrogen permeability. One had to estimate the parameters of diffusion and sorption to numerically model the different scenarios and experimental conditions of the material usage (including extreme ones), and identify the limiting factors. This paper presents a nonlinear mathematical model taking into account the dynamics of sorption-desorption processes and reversible capture of diffusing hydrogen by inhomogeneity of the material’s structure, and also modification of the model when the transport rate is high. The results of numerical modelling allow to obtain information about output data sensitivity with respect to variations of the material’s hydrogen permeability parameters. Furthermore, it is possible to analyze the dynamics of concentrations and fluxes that cannot be measured directly. Experimental data for Ta77Nb23 and V85Ni15 alloys were used to test the model. This work is supported by the Russian Foundation for Basic Research (Project No. 15-01-00744).

Modeling of hydrogen/deuterium dynamics and heat generation on palladium nanoparticles for hydrogen storage and solid-state nuclear fusion

Directory of Open Access Journals (Sweden)

Katsuaki Tanabe

2016-01-01

Full Text Available We modeled the dynamics of hydrogen and deuterium adsorbed on palladium nanoparticles including the heat generation induced by the chemical adsorption and desorption, as well as palladium-catalyzed reactions. Our calculations based on the proposed model reproduce the experimental time-evolution of pressure and temperature with a single set of fitting parameters for hydrogen and deuterium injection. The model we generated with a highly generalized set of formulations can be applied for any combination of a gas species and a catalytic adsorbent/absorbent. Our model can be used as a basis for future research into hydrogen storage and solid-state nuclear fusion technologies.

Characterizing particle-scale equilibrium adsorption and kinetics of uranium(VI) desorption from U-contaminated sediments

Science.gov (United States)

Stoliker, Deborah L.; Liu, Chongxuan; Kent, Douglas B.; Zachara, John M.

2013-01-01

Rates of U(VI) release from individual dry-sieved size fractions of a field-aggregated, field-contaminated composite sediment from the seasonally saturated lower vadose zone of the Hanford 300-Area were examined in flow-through reactors to maintain quasi-constant chemical conditions. The principal source of variability in equilibrium U(VI) adsorption properties of the various size fractions was the impact of variable chemistry on adsorption. This source of variability was represented using surface complexation models (SCMs) with different stoichiometric coefficients with respect to hydrogen ion and carbonate concentrations for the different size fractions. A reactive transport model incorporating equilibrium expressions for cation exchange and calcite dissolution, along with rate expressions for aerobic respiration and silica dissolution, described the temporal evolution of solute concentrations observed during the flow-through reactor experiments. Kinetic U(VI) desorption was well described using a multirate SCM with an assumed lognormal distribution for the mass-transfer rate coefficients. The estimated mean and standard deviation of the rate coefficients were the same for all Micropore volumes, assessed using t-plots to analyze N2 desorption data, were also the same for all dry-sieved micropore volumes and mass-transfer rate properties. Pore volumes for dry-sieved size fractions exceeded values for the corresponding wet-sieved fractions. We hypothesize that repeated field wetting and drying cycles lead to the formation of aggregates and/or coatings containing (micro)pore networks which provided an additional mass-transfer resistance over that associated with individual particles. The 2–8 mm fraction exhibited a larger average and standard deviation in the distribution of mass-transfer rate coefficients, possibly caused by the abundance of microporous basaltic rock fragments.

Hydrogenation Properties of TiFe Doped with Zirconium

Directory of Open Access Journals (Sweden)

Catherine Gosselin

2015-11-01

Full Text Available The goal of this study was to optimize the activation behaviour of hydrogen storage alloy TiFe. We found that the addition of a small amount of Zr in TiFe alloy greatly reduces the hydrogenation activation time. Two different procedural synthesis methods were applied: co-melt, where the TiFe was melted and afterward re-melted with the addition of Zr, and single-melt, where Ti, Fe and Zr were melted together in one single operation. The co-melted sample absorbed hydrogen at its maximum capacity in less than three hours without any pre-treatment. The single-melted alloy absorbed its maximum capacity in less than seven hours, also without pre-treatment. The reason for discrepancies between co-melt and single-melt alloys was found to be the different microstructure. The effect of air exposure was also investigated. We found that the air-exposed samples had the same maximum capacity as the argon protected samples but with a slightly longer incubation time, which is probably due to the presence of a dense surface oxide layer. Scanning electron microscopy revealed the presence of a rich Zr intergranular phase in the TiFe matrix, which is responsible for the enhanced hydrogenation properties of these Zr-doped TiFe alloys.

Qualitative and quantitative analysis of complex temperature-programmed desorption data by multivariate curve resolution

Science.gov (United States)

Rodríguez-Reyes, Juan Carlos F.; Teplyakov, Andrew V.; Brown, Steven D.

2010-10-01

The substantial amount of information carried in temperature-programmed desorption (TPD) experiments is often difficult to mine due to the occurrence of competing reaction pathways that produce compounds with similar mass spectrometric features. Multivariate curve resolution (MCR) is introduced as a tool capable of overcoming this problem by mathematically detecting spectral variations and correlations between several m/z traces, which is later translated into the extraction of the cracking pattern and the desorption profile for each desorbate. Different from the elegant (though complex) methods currently available to analyze TPD data, MCR analysis is applicable even when no information regarding the specific surface reaction/desorption process or the nature of the desorbing species is available. However, when available, any information can be used as constraints that guide the outcome, increasing the accuracy of the resolution. This approach is especially valuable when the compounds desorbing are different from what would be expected based on a chemical intuition, when the cracking pattern of the model test compound is difficult or impossible to obtain (because it could be unstable or very rare), and when knowing major components desorbing from the surface could in more traditional methods actually bias the quantification of minor components. The enhanced level of understanding of thermal processes achieved through MCR analysis is demonstrated by analyzing three phenomena: i) the cryogenic desorption of vinyltrimethylsilane from silicon, an introductory system where the known multilayer and monolayer components are resolved; ii) acrolein hydrogenation on a bimetallic Pt-Ni-Pt catalyst, where a rapid identification of hydrogenated products as well as other desorbing species is achieved, and iii) the thermal reaction of Ti[N(CH 3) 2] 4 on Si(100), where the products of surface decomposition are identified and an estimation of the surface composition after the

Hydrogen system (hydrogen fuels feasibility)

International Nuclear Information System (INIS)

Guarna, S.

1991-07-01

This feasibility study on the production and use of hydrogen fuels for industry and domestic purposes includes the following aspects: physical and chemical properties of hydrogen; production methods steam reforming of natural gas, hydrolysis of water; liquid and gaseous hydrogen transportation and storage (hydrogen-hydride technology); environmental impacts, safety and economics of hydrogen fuel cells for power generation and hydrogen automotive fuels; relevant international research programs

Influence of post-hydrogenation upon electrical, optical and structural properties of hydrogen-less sputter-deposited amorphous silicon

Energy Technology Data Exchange (ETDEWEB)

Gerke, S., E-mail: sebastian.gerke@uni-konstanz.de [Department of Physics, University of Konstanz, Konstanz, 78457 (Germany); Becker, H.-W.; Rogalla, D. [RUBION — Central Unit for Ion Beams and Radioisotopes, University of Bochum, Bochum, 44780 (Germany); Singer, F.; Brinkmann, N.; Fritz, S.; Hammud, A.; Keller, P.; Skorka, D.; Sommer, D. [Department of Physics, University of Konstanz, Konstanz, 78457 (Germany); Weiß, C. [Fraunhofer Institute for Solar Energy Systems ISE, Heidenhofstraße 2, 79110 Freiburg (Germany); Flege, S. [Department of Materials Science, TU Darmstadt, Darmstadt 64287 (Germany); Hahn, G. [Department of Physics, University of Konstanz, Konstanz, 78457 (Germany); Job, R. [Department of Electrical Engineering and Computer Science, Münster University of Applied Sciences, Steinfurt 48565 (Germany); Terheiden, B. [Department of Physics, University of Konstanz, Konstanz, 78457 (Germany)

2016-01-01

further hydrogen diffusion experiments which require an initially unhydrogenated drain layer. - Highlights: • Post-hydrogenation of hydrogen-less RF sputter deposited a-Si • Hydrogen depth profiling of the ongoing post-hydrogenation process by NRRA • Determining diffusion coefficients of H and related diffusion mechanism • Analyze changes in elec., opt. and struct. properties of a-Si during post-hydro • Achieving surface passivation during post-hydrogenation of H-less deposited a-Si.

Fluctuations of electrical and mechanical properties of diamond induced by interstitial hydrogen

Science.gov (United States)

Zhuang, Chun-Qiang; Liu, Lei

2015-01-01

While experimental evidence demonstrates that the presence of hydrogen (H) impurities in diamond films plays a significant role in determining their physical properties, the small radius of the H atom makes detecting such impurities quite a challenging task. In the present work, first-principles calculations were employed to provide an insight into the effects of the interstitial hydrogen on the electrical and mechanical properties of diamond crystals at the atomic level. The migrated pathways of the interstitial hydrogen are dictated by energetic considerations. Some new electronic states are formed near the Fermi level. The interstitial hydrogen markedly narrows the bandgap of the diamond and weakens the diamond crystal. The obvious decrement of the critical strain clearly implies the presence of an H-induced embrittlement effect. Project supported by the Project of Construction of Innovative Teams and Teacher Career Development for Universities and Colleges under Beijing Municipality, China (Grant No. IDHT20140504), the National Natural Science Foundation of China (Grant No. 51402009), and the Foundation for Young Scholars of Beijing University of Technology, China.

Temperature dependence of CO desorption kinetics at a novel Pt-on-Au/C PEM fuel cell anode

DEFF Research Database (Denmark)

Pitois, A.; Pilenga, A.; Pfrang, A.

2010-01-01

techniques. The temperature dependence of the CO desorption process on this system has been investigated using isotopic exchange experiments. The CO desorption kinetics have been studied as a function of temperature and flow rate. Desorption rate constants have been measured for a temperature range between...... degrees C. The dependence in temperature of the desorption rate constants for the novel Pt-on-Au/C system is however much lower than that observed for the Pt/C system. This suggests that the nature of the substrate has a significant influence on the catalyst surface properties. It shows that, in surface...... 25 and 150 degrees C. These desorption rate constants have been compared with the benchmarking desorption rate data obtained for the commercial Pt/C catalyst under similar experimental conditions. A comparable desorption rate constant for the Pt-on-Au/C and Pt/C systems has been obtained at 25...

Sorption Enhanced Reaction Process (SERP) for production of hydrogen

Energy Technology Data Exchange (ETDEWEB)

Anand, M.; Hufton, J.; Mayorga, S. [Air Products and Chemicals, Inc., Allentown, PA (United States)] [and others

1996-10-01

Sorption Enhanced Reaction Process (SERP) is a novel process that is being developed for the production of lower cost hydrogen by steam-methane reforming (SMR). In this process the reaction of methane with steam is carried out in the presence of an admixture of a catalyst and a selective adsorbent for carbon dioxide. The key consequences of SERP are: (i) reformation reaction is carried out at a significantly lower temperature (300-500{degrees}C) than that in a conventional SMR reactor (800-1100{degrees}C), while achieving the same conversion of methane to hydrogen, (ii) the product hydrogen is obtained at reactor pressure (200-400 psig) and at 98+% purity directly from the reactor (compared to only 70-75% H{sub 2} from conventional SMR reactor), (iii) downstream hydrogen purification step is either eliminated or significantly reduced in size. The first phase of the program has focused on the development of a sorbent for CO{sub 2} which has (a) reversible CO{sub 2} capacity >0.3 mmol/g at low partial pressures of CO{sub 2} (0.1 - 1.0 atm) in the presence of excess steam (pH{sub 2}O/pCO{sub 2}>20) at 400-500{degrees}C and (b) fast sorption-desorption kinetics for CO{sub 2}, at 400-500{degrees}C. Several families of supported sorbents have been identified that meet the target CO{sub 2} capacity. A few of these sorbents have been tested under repeated sorption/desorption cycles and extended exposure to high pressure steam at 400-500{degrees}C. One sorbent has been scaled up to larger quantities (2-3 kg) and tested in the laboratory process equipment for sorption and desorption kinetics of CO{sub 2}. The CO{sub 2}, sorption and desorption kinetics are desirably fast. This was a critical path item for the first phase of the program and now has been successfully demonstrated. A reactor has been designed that will allow nearly isothermal operation for SERP-SMR. This reactor was integrated into an overall process flow diagram for the SERP-SMR process.

Design and integration of a hydrogen storage on metallic hydrides

International Nuclear Information System (INIS)

Botzung, M.

2008-01-01

This work presents a hydrogen storage system using metal hydrides for a Combined Heat and Power (CHP) system. Hydride storage technology has been chosen due to project specifications: high volumetric capacity, low pressures (≤ 3.5 bar) and low temperatures (≤ 75 C: fuel cell temperature). During absorption, heat from hydride generation is dissipated by fluid circulation. An integrated plate-fin type heat exchanger has been designed to obtain good compactness and to reach high absorption/desorption rates. At first, the storage system has been tested in accordance with project specifications (absorption 3.5 bar, desorption 1.5 bar). Then, the hydrogen charge/discharge times have been decreased to reach system limits. System design has been used to simulate thermal and mass comportment of the storage tank. The model is based on the software Fluent. We take in consideration heat and mass transfers in the porous media during absorption/desorption. The hydride thermal and mass behaviour has been integrated in the software. The heat and mass transfers experimentally obtained have been compared to results calculated by the model. The influence of experimental and numerical parameters on the model behaviour has also been explored. (author) [fr

Prospects for hydrogen storage in graphene.

Science.gov (United States)

Tozzini, Valentina; Pellegrini, Vittorio

2013-01-07

Hydrogen-based fuel cells are promising solutions for the efficient and clean delivery of electricity. Since hydrogen is an energy carrier, a key step for the development of a reliable hydrogen-based technology requires solving the issue of storage and transport of hydrogen. Several proposals based on the design of advanced materials such as metal hydrides and carbon structures have been made to overcome the limitations of the conventional solution of compressing or liquefying hydrogen in tanks. Nevertheless none of these systems are currently offering the required performances in terms of hydrogen storage capacity and control of adsorption/desorption processes. Therefore the problem of hydrogen storage remains so far unsolved and it continues to represent a significant bottleneck to the advancement and proliferation of fuel cell and hydrogen technologies. Recently, however, several studies on graphene, the one-atom-thick membrane of carbon atoms packed in a honeycomb lattice, have highlighted the potentialities of this material for hydrogen storage and raise new hopes for the development of an efficient solid-state hydrogen storage device. Here we review on-going efforts and studies on functionalized and nanostructured graphene for hydrogen storage and suggest possible developments for efficient storage/release of hydrogen under ambient conditions.

Equilibrium properties of dense hydrogen isotope gases based on the theory of simple fluids.

Science.gov (United States)

Kowalczyk, Piotr; MacElroy, J M D

2006-08-03

We present a new method for the prediction of the equilibrium properties of dense gases containing hydrogen isotopes. The proposed approach combines the Feynman-Hibbs effective potential method and a deconvolution scheme introduced by Weeks et al. The resulting equations of state and the chemical potentials as functions of pressure for each of the hydrogen isotope gases depend on a single set of Lennard-Jones parameters. In addition to its simplicity, the proposed method with optimized Lennard-Jones potential parameters accurately describes the equilibrium properties of hydrogen isotope fluids in the regime of moderate temperatures and pressures. The present approach should find applications in the nonlocal density functional theory of inhomogeneous quantum fluids and should also be of particular relevance to hydrogen (clean energy) storage and to the separation of quantum isotopes by novel nanomaterials.

The Inverse Problem of Identification of Hydrogen Permeability Model

Directory of Open Access Journals (Sweden)

Yury V. Zaika

2018-01-01

Full Text Available One of the technological challenges for hydrogen materials science is the currently active search for structural materials with important applications (including the ITER project and gas-separation plants. One had to estimate the parameters of diffusion and sorption to numerically model the different scenarios and experimental conditions of the material usage (including extreme ones. The article presents boundary value problems of hydrogen permeability and thermal desorption with dynamical boundary conditions. A numerical method is developed for TDS spectrum simulation, where only integration of a nonlinear system of low order ordinary differential equations is required. The main final output of the article is a noise-resistant algorithm for solving the inverse problem of parametric identification for the aggregated experiment where desorption and diffusion are dynamically interrelated (without the artificial division of studies into the diffusion limited regime (DLR and the surface limited regime (SLR.

Investigation of polyelectrolyte desorption by single molecule force spectroscopy

International Nuclear Information System (INIS)

Friedsam, C; Seitz, M; Gaub, H E

2004-01-01

Single molecule force spectroscopy has evolved into a powerful method for the investigation of intra- and intermolecular interactions at the level of individual molecules. Many examples, including the investigation of the dynamic properties of complex biological systems as well as the properties of covalent bonds or intermolecular transitions within individual polymers, are reported in the literature. The technique has recently been extended to the systematic investigation of desorption processes of individual polyelectrolyte molecules adsorbed on generic surfaces. The stable covalent attachment of polyelectrolyte molecules to the AFM-tip provides the possibility of performing long-term measurements with the same set of molecules and therefore allows the in situ observation of the impact of environmental changes on the adsorption behaviour of individual molecules. Different types of interactions, e.g. electrostatic or hydrophobic interactions, that determine the adsorption process could be identified and characterized. The experiments provided valuable details that help to understand the nature and the properties of non-covalent interactions, which is helpful with regard to biological systems as well as for technical applications. Apart from this, desorption experiments can be utilized to characterize the properties of surfaces or polymer coatings. Therefore they represent a versatile tool that can be further developed in terms of various aspects

New Transition metal assisted complex borohydrides for hydrogen storage

International Nuclear Information System (INIS)

Sesha Srinivasan; Elias Lee Stefanakos; Yogi Goswami

2006-01-01

High capacity hydrogen storage systems are indeed essential for the on-board vehicular application that leads to the pollution free environment. Apart from the various hydrogen storage systems explored in the past, complex hydrides involving light weight alkali/alkaline metals exhibits promising hydrogenation/ dehydrogenation characteristics. New transition metal assisted complex borohydrides [Zn(BH 4 ) 2 ] have been successfully synthesized by an inexpensive mechano-chemical process. These complex hydrides possesses gravimetric hydrogen storage capacity of ∼8.4 wt.% at around 120 C. We have determined the volumetric hydrogen absorption and desorption of these materials for a number of cycles. Another complex borohydride mixture LiBH 4 /MgH 2 catalyzed with ZnCl 2 has been synthesized and characterized using various analytical techniques. (authors)

Influence of M=Al, Ga and Si on microstructure and HDDR-processing of Sm2(Fe,M)17 and magnetic properties of their nitrides and carbides

International Nuclear Information System (INIS)

Kubis, M.; Gutfleisch, O.; Gebel, B.; Mueller, K.-H.; Schultz, L.

1999-01-01

Microstructural investigations by means of scanning electron microscopy and X-ray diffraction showed that the formation of high amounts of α-Fe in as-cast Sm 2 (Fe,M) 17 alloys can be suppressed by using the substitutions M=Al or Si together with excess Sm. Ga, on the other hand, does not induce this beneficial effect. The hydrogen absorption and desorption behaviour was investigated by temperature-pressure-analysis and hydrogen differential thermal analysis. Decreasing amounts of hydrogen were absorbed in Sm 2 (Fe,M) 17 for increasing contents of all substitutions M=Ga, Al and Si due to their stabilising effect on the 2:17 phase with regard to its disproportionation. Compared with the homogenised alloys, the as-cast materials show a weaker interstitial hydrogen absorption and a stronger disproportionation reaction at lower temperatures due to the higher content of Sm-rich phases in the as-cast alloys. A second cycle of the hydrogenation-disproportionation-desorption-recombination (HDDR) process leads to a faster disproportionation reaction at lower temperatures due to the grain refinement during the first cycle. Magnetic properties of as-cast and homogenised materials were investigated after HDDR treatment and nitrogenation or carburisation of pre-milled powders. Nitrogenated and carburised samples showed coercivities up to 3.0 T and 2.3 T, respectively. There were only slight differences of the magnetic properties of materials prepared from homogenised and from as-cast samples. (orig.)

Extrapolation studies on desorption of thorium and uranium at different solution compositions on contaminated soil sediments (Malaysia)

International Nuclear Information System (INIS)

Syed Hakimi Sakuma

2000-01-01

By means of batch desorption experiments, the thorium and uranium desorption properties of contaminated soil sediments are investigated as a function of the effect of cations present in the groundwater. A phenomenological correlation between the desorption coefficient and the concentration of Ca and Mg in the water is determined. Kd Thorium -0.15849 ± 0.03237 log (Ca + Mg) + 5.06715 ± 0.09106; Kd Uranium = -0.11984 ± 0.03237 log (Ca + Mg) + 2.99909 ± 0.09105. By these models the sorption/desorption behaviour of soils can be predicted phenomenologically as function of the groundwater composition. (author)

TEM studies of nanostructure in melt-spun Mg-Ni-La alloy manifesting enhanced hydrogen desorbing kinetics

International Nuclear Information System (INIS)

Tanaka, K.; Miwa, T.; Sasaki, K.; Kuroda, K.

2009-01-01

The hydrogen storage properties of a magnesium-rich Mg-Ni-La alloy prepared by melt-spinning are significantly improved by nanostructure formation during crystallization and activation. It can absorb and desorb ∼5 wt% hydrogen at temperatures as low as 200 deg. C in moderate time periods. Transmission electron microscopic (TEM) studies on this alloy indicate that the nanostructure, consisting of LaH 3 and Mg 2 NiH 4 nano-particles dispersed homogeneously in MgH 2 matrices after hydrogenation, is rather stable at temperatures below 300 deg. C but undergoes coarsening and segregation of these particles and matrices above ∼400 deg. C. These structural changes have been confirmed by electron energy-loss spectroscopic (EELS) imaging as well as high-resolution TEM techniques. A new EELS peak associated with a plasmon excitation in the MgH 2 phase (H-plasmon) is found for the first time in this study. By imaging the H-plasmon peak, the hydrogen distribution in the alloy has been clearly visualized. We have succeeded in observing the hydrogen desorption process at ∼400 deg. C in-situ in the microscope using this EELS imaging technique.

The electronic and optical properties of amorphous silica with hydrogen defects by ab initio calculations

Science.gov (United States)

Ren, Dahua; Xiang, Baoyan; Hu, Cheng; Qian, Kai; Cheng, Xinlu

2018-04-01

Hydrogen can be trapped in the bulk materials in four forms: interstitial molecular H2, interstitial atom H, O‑H+(2Si=O–H)+, Si‑H‑( {{4O}}\\bar \\equiv {{Si&x2212H}})‑ to affect the electronic and optical properties of amorphous silica. Therefore, the electronic and optical properties of defect-free and hydrogen defects in amorphous silica were performed within the scheme of density functional theory. Initially, the negative charged states hydrogen defects introduced new defect level between the valence band top and conduction band bottom. However, the neutral and positive charged state hydrogen defects made both the valence band and conduction band transfer to the lower energy. Subsequently, the optical properties such as absorption spectra, conductivity and loss functions were analyzed. It is indicated that the negative hydrogen defects caused the absorption peak ranging from 0 to 2.0 eV while the positive states produced absorption peaks at lower energy and two strong absorption peaks arose at 6.9 and 9.0 eV. However, the neutral hydrogen defects just improved the intensity of absorption spectrum. This may give insights into understanding the mechanism of laser-induced damage for optical materials. Project supported by the Science and Technology of Hubei Provincial Department of Education (No. B2017098).

Reaction dynamics of molecular hydrogen on silicon surfaces

DEFF Research Database (Denmark)

Bratu, P.; Brenig, W.; Gross, A.

1996-01-01

of the preexponential factor by about one order of magnitude per lateral degree of freedom. Molecular vibrations have practically no effect on the adsorption/desorption dynamics itself, but lead to vibrational heating in desorption with a strong isotope effect. Ab initio calculations for the H-2 interaction...... between the two surfaces. These results indicate that tunneling, molecular vibrations, and the structural details of the surface play only a minor role for the adsorption dynamics. Instead, they appear to be governed by the localized H-Si bonding and Si-Si lattice vibrations. Theoretically, an effective......Experimental and theoretical results on the dynamics of dissociative adsorption and recombinative desorption of hydrogen on silicon are presented. Using optical second-harmonic generation, extremely small sticking probabilities in the range 10(-9)-10(-5) could be measured for H-2 and D-2 on Si(111...

Mechanism of NH{sub 3} desorption during the reaction of H{sub 2} with nitrogen containing carbonaceous materials

Energy Technology Data Exchange (ETDEWEB)

Juan F. Espinal; Thanh N. Truong; Fanor Mondragon [University of Antioquia, Medellin (Colombia). Institute of Chemistry

2005-07-01

The continued increase in demand for natural gas has stimulated the interest in coal conversion to methane as synthetic natural gas by hydropyrolysis of coal (pyrolysis in a H{sub 2} atmosphere). Because the produced raw gas contains considerable amounts of gaseous N-containing products that have to be removed before delivering to final users, the information on distribution of coal-N is important for designing purification processes. It has been reported in the literature that NH{sub 3} is the main nitrogen containing gas that is released during the hydropyrolysis process. Other gases such as HCN and N{sub 2} are also released but in a much smaller amount. To the best of our knowledge, the mechanism for NH{sub 3} desorption during hydrogen reaction with carbonaceous materials has not been studied. We carried out a molecular modeling study using Density Functional Theory in order to get an insight of the mechanism and thermodynamics for NH{sub 3} evolution using pyridinic nitrogen as a model of N-containing carbonaceous material. We propose a mechanism that involves consecutive hydrogenation steps that lead to C-N bond breakage and NH{sub 3} desorption to the gas phase. It was found that the first hydrogenation reaction is highly exothermic. However, further hydrogenations are endothermic. Several pathways for NH{sub 3} evolution were proposed and most of them show high exothermicity. 17 refs., 2 figs.

[Applications of self-renewing coatings to improved vacuum materials, hydrogen permeation barriers and sputter-resistant materials

International Nuclear Information System (INIS)

1985-01-01

The phenomena of Gibbsian segregation, radiation-induced segregation and radiation-induced precipitation modify the surface composition and properties of alloys and compounds. In some cases, the change in properties is both substantial and useful, the most notable example being that of stainless steel. When surface-modifying phenomena are investigated as a class, a number of additional materials emerge as candidates for study, having potential applications in a number of technologically important areas. These materials are predicted to produce self-sustaining coatings which provide hydrogen permeation barriers, low-sticking and stimulated desorption coefficients for vacuum applications, and low-Z, sputtering-resistant surfaces for fusion applications. Several examples of each type of material are presented, along with a discussion of the experimental verification of their properties and the status of the corresponding applications development program

Correlação entre a estrutura atômica superficial e o processo de adsorção-dessorção reversível de hidrogênio em eletrodos monocristalinos Pt(111, Pt(100 e Pt(110 The correlation between the atomic surface structure and the reversible adsorption-desorption of hydrogen on single crystal Pt (111, Pt (100 and Pt (110 electrodes

Directory of Open Access Journals (Sweden)

Valderi Pacheco dos Santos

2001-12-01

Full Text Available Platinum is widely used as electrode in electrocatalytic processes, however the use of polycrystalline electrodes introduces a series of variables in the electrochemical system due to the aleatory contribution of all the crystallographic orientations with different surface packing of atoms. Single crystal platinum electrodes of low Miller index present surface structure of high regularity and serve as model to establish a correlation among the macroscopic and microscopic properties of the electrochemical interface. Therefore, the main aim of this work is the study of the voltammetric profiles of the reversible adsorption-desorption of hydrogen on Pt(100, Pt(110 and Pt(111, in order to correlate the electrochemical properties of each different orientation with the surface atomic structure.

Nanoporous materials for hydrogen storage and H2/D2 isotope separation

International Nuclear Information System (INIS)

Oh, Hyunchul

2014-01-01

This thesis presents a study of hydrogen adsorption properties at RT with noble metal doped porous materials and an efficient separation of hydrogen isotopes with nanoporous materials. Most analysis is performed via thermal desorption spectra (TDS) and Sieverts-type apparatus. The result and discussion is presented in two parts; Chapter 4 focuses on metal doped nanoporous materials for hydrogen storage. Cryogenic hydrogen storage by physisorption on porous materials has the advantage of high reversibility and fast refuelling times with low heat evolution at modest pressures. At room temperature, however, the physisorption mechanism is not abEle to achieve enough capacity for practical application due to the weak van der Waals interaction, i.e., low isosteric heats for hydrogen sorption. Recently, the ''spillover'' effect has been proposed by R. Yang et al. to enhance the room temperature hydrogen storage capacity. However, the mechanism of this storage enhancement by decoration of noble metal particles inside high surface area supports is not yet fully understood and still under debate. In this chapter, noble metal (Pt / Pd) doped nanoporous materials (i.e. porous carbon, COFs) have been investigated for room temperature hydrogen storage. Their textural properties and hydrogen storage capacity are characterized by various analytic techniques (e.g. SEM, HRTEM, XRD, BET, ICP-OES, Thermal desorption spectra, Sievert's apparatus and Raman spectroscopy). Firstly, Pt-doped and un-doped templated carbons possessing almost identical textural properties were successfully synthesized via a single step wet impregnation method. This enables the study of Pt catalytic activities and hydrogen adsorption kinetics on porous carbons at ambient temperature by TDS after H 2 /D 2 gas exposure and PCT measurement, respectively. While the H 2 adsorption kinetics in the microporous structure is enhanced by Pt catalytic activities (spillover), only a small enhancement of the hydrogen

The kinetics of hydrogen removal from liquid sodium

International Nuclear Information System (INIS)

Gwyther, J.R.; Whittingham, A.C.

1981-01-01

The rates of hydrogen removal from liquid sodium-sodium hydride mixtures have been measured as a function of sodium stirring rate at temperatures up to 420 0 C. Two techniques have been employed - removal under continuous evacuation in which hydrogen flow rates were measured using a capillary flow technique and by argon purging in which hydrogen concentrations in the argon carrier gas were measured by gas chromatography. The results have been used to assess the feasibility of thermal decomposition of sodium hydride for the regeneration of hydride-laden LMFBR cold traps. Studies on the kinetics of desorption of hydrogen from solution in liquid sodium at temperatures up to 400 0 C are also presented and possible kinetic mechanisms discussed. (orig.)

On the structural and optical properties of sputtered hydrogenated amorphous silicon thin films

International Nuclear Information System (INIS)

Barhdadi, A.; Chafik El ldrissi, M.

2002-08-01

The present work is essentially focused on the study of optical and structural properties of hydrogenated amorphous silicon thin films (a-Si:H) prepared by radio-frequency cathodic sputtering. We examine separately the influence of hydrogen partial pressure during film deposition, and the effect of post-deposition thermal annealings on the main optical characteristics of the layers such as refraction index, optical gap and Urbach energy. Using the grazing X-rays reflectometry technique, thin film structural properties are examined immediately after films deposition as well as after surface oxidation or annealing. We show that low hydrogen pressures allow a saturation of dangling bonds in the layers, while high doses lead to the creation of new defects. We show also that thermal annealing under moderate temperatures improves the structural quality of the deposited layers. For the films examined just after deposition, the role of hydrogen appears in the increase of their density. For those analysed after a short stay in the ambient, hydrogen plays a protective role against the oxidation of their surfaces. This role disappears for a long time stay in the ambient. (author)

Electron Stimulated Molecular Desorption of a NEG St 707 at Room Temperature

CERN Document Server

Le Pimpec, F; Laurent, Jean Michel

2001-01-01

Electron stimulated molecular desorption (ESD) from a NEG St 707 (SAES GettersTM) sample after conditioning and after saturation with isotopic carbon monoxide2,13C18O, has been studied on a laboratory setup. Measurements were performed using an electron beam of 300 eV kinetic energy, with an average electron intensity of 1.6 1015 electrons s-1. The electrons were impinging on the 15 cm2 target surface at perpendicular incidence. It is found that the desorption yields h (molecules/electron) of the characteristic gases in an UHV system (hydrogen, methane, water, carbon monoxide, carbon dioxide) for a fully activated NEG as well as for a NEG fully saturated with 13C18O are lower than for OFHC copper baked at 120oC. A small fraction only of the gas which is required to saturate the getter surface can be re-desorbed and thus appears to be accessible to ESD.

Mechanism of calcium oxide excitation by atom hydrogen

International Nuclear Information System (INIS)

Kharlamov, V.F.

1991-01-01

Heterogeneous recombination of hydrogen atoms on the surface of calcium oxide proceeds according to the Langmuir-Hinshelwood mechanism with participation of atoms in two different states, belonging to adsorption centres of the same type. CaO excitation is broughty about by vibration-electron transitions during associative desorption of H 2 molecules

Studies of Modified Hydrogen Storage Intermetallic Compounds Used as Fuel Cell Anodes

Directory of Open Access Journals (Sweden)

Rui F. M. Lobo

2011-12-01

Full Text Available The possibility of substituting Pt/C with the hydrogen storage alloy MlNi3.6Co0.85Al0.3Mn0.3 as the anode active material of a proton exchange membrane fuel cell system has been analyzed. The electrochemical properties indicate that a much more electrochemically active anode is obtained by impregnating the active material loaded anode in a Nafion proton conducting polymer. Such performance improvement might result from the increase of three-phase boundary sites or length in the gas diffusion electrode where the electrochemical reaction occurs. The experimental data revealed that the membrane electrode assembly (MEA shows better results when the anode active material, MlNi3.6Co0.85Al0.3Mn0.3, is treated with a hot alkaline KBH4 solution, and then chemically coated with 3 wt.% Pd. The MEA with the aforesaid modification presents an enhanced surface capability for hydrogen adsorption, and has been studied by molecular beam-thermal desorption spectrometry.

Study of edge plasma properties comparing operation in hydrogen and helium in RFX

International Nuclear Information System (INIS)

Spolaore, M.; Antoni, V.; Bagatin, M.; Desideri, D.; Fattorini, L.; Martines, E.; Serianni, G.; Tramontin, L.; Vianello, N.

2001-01-01

The properties of the edge plasma in the reversed field pinch RFX have been investigated by comparing the operation in helium with those normally performed in hydrogen. It has been found that a spontaneous velocity shear layer takes place in the edge region also in helium discharges. The edge structure of hydrogen and helium discharges have been interpreted using a momentum balance equation, which takes into account anomalous viscosity and friction with neutrals. The electrostatic turbulence properties are also compared: it is found that electrostatic turbulence drives most of the particle losses and a small fraction of the energy losses also for the He discharges. The modifications of the mean profiles, including the ExB velocity, during PPCD are briefly discussed and compared with the results obtained in hydrogen

Influence of M=Al, Ga and Si on microstructure and HDDR-processing of Sm{sub 2}(Fe,M){sub 17} and magnetic properties of their nitrides and carbides

Energy Technology Data Exchange (ETDEWEB)

Kubis, M.; Gutfleisch, O.; Gebel, B.; Mueller, K.-H.; Schultz, L. [Institut fuer Festkoerper- und Werkstofforschung Dresden e.V. (Germany). Inst. fuer Metallische Werkstoffe; Harris, I.R. [School of Metallurgy and Materials, University of Birmingham, Birmingham, B15 2TT (United Kingdom)

1999-02-01

Microstructural investigations by means of scanning electron microscopy and X-ray diffraction showed that the formation of high amounts of {alpha}-Fe in as-cast Sm{sub 2}(Fe,M){sub 17} alloys can be suppressed by using the substitutions M=Al or Si together with excess Sm. Ga, on the other hand, does not induce this beneficial effect. The hydrogen absorption and desorption behaviour was investigated by temperature-pressure-analysis and hydrogen differential thermal analysis. Decreasing amounts of hydrogen were absorbed in Sm{sub 2}(Fe,M){sub 17} for increasing contents of all substitutions M=Ga, Al and Si due to their stabilising effect on the 2:17 phase with regard to its disproportionation. Compared with the homogenised alloys, the as-cast materials show a weaker interstitial hydrogen absorption and a stronger disproportionation reaction at lower temperatures due to the higher content of Sm-rich phases in the as-cast alloys. A second cycle of the hydrogenation-disproportionation-desorption-recombination (HDDR) process leads to a faster disproportionation reaction at lower temperatures due to the grain refinement during the first cycle. Magnetic properties of as-cast and homogenised materials were investigated after HDDR treatment and nitrogenation or carburisation of pre-milled powders. Nitrogenated and carburised samples showed coercivities up to 3.0 T and 2.3 T, respectively. There were only slight differences of the magnetic properties of materials prepared from homogenised and from as-cast samples. (orig.) 21 refs.

Visualization of hydrogen in steels by secondary ion mass spectrometry

International Nuclear Information System (INIS)

Takai, Kenichi

2000-01-01

Secondary ion mass spectrometry (SIMS) enables us to visualize hydrogen trapping sites in steels. Information about the hydrogen trapping sites in high-strength steels by SIMS is very important to discuss environmental embrittlement mechanism for developing steels with a high resistance to the environmental embrittlement. Secondary ion image analysis by SIMS has made possible to visualize the hydrogen and deuterium trapping sites in the steels. Hydrogen in tempered martensite steels containing Ca tends to accumulate on inclusions, at grain boundaries, and in segregation bands. Visualization of hydrogen desorption process by secondary ion image analysis confirms that the bonding between the inclusions and the hydrogen is strong. Cold-drawn pearlite steels trap hydrogen along cold-drawing direction. Pearlite phase absorbs the hydrogen more than ferrite phase does. This article introduces the principle of SIMS, its feature, analysis method, and results of hydrogen visualization in steels. (author)

Phosphorus Adsorption and Desorption Properties of Minnesota Basalt Lunar Simulant and Lunar Glass Simulant

Science.gov (United States)

Sutter, Brad; Hossner, Lloyd R.; Ming, Douglas W.

1996-01-01

Phosphorus (P) adsorption and desorption characteristics of Minnesota Basalt Lunar Simulant (MBLS) and Lunar Glass Simulant (LGS) were evaluated. Results of P interactions with lunar simulants indicated that mineral and glass components adsorbed between 50 and 70% of the applied P and that between 85 and 100% of the applied P was desorbed. The Extended Freundlich equation best described the adsorption data (r(sup 2) = 0.92), whereas the Raven/Hossner equation best described the desorption data ((r(sup 2) = 0.97). Kinetic desorption results indicated that MBLS and LGS released most of their P within 15 h. The expanded Elovich equation fit the data best at shorter times while t/Q(sub DT) equation had a better fit at longer times. These results indicate that P does not strongly adsorb to the two simulants and that any P that was adsorbed was readily desorbed in the presence of anion exchange resin. This work suggests that multiple small applications of P (10-20 mg P/kg) should be added to the simulants to ensure adequate solution P for plant uptake and efficient use of P fertilizer.

Mechanism of the electrochemical hydrogen reaction on smooth tungsten carbide and tungsten electrodes

International Nuclear Information System (INIS)

Wiesener, K.; Winkler, E.; Schneider, W.

1985-01-01

The course of the electrochemical hydrogen reaction on smooth tungsten-carbide electrodes in hydrogen saturated 2.25 M H 2 SO 4 follows a electrochemical sorption-desorption mechanism in the potential range of -0.4 to +0.1 V. At potentials greater than +0.1 V the hydrogen oxidation is controlled by a preliminary chemical sorption step. Concluding from the similar behaviour of tungsten-carbide and tungsten electrodes after cathodic pretreatment, different tungsten oxides should be involved in the course of the hydrogen reaction on tungsten carbide electrodes. (author)

Effect of fluorination treatment on electrochemical properties of M1Ni{sub 3.5}Co{sub 0.6}Mn{sub 0.4}Al{sub 0.5} hydrogen storage alloy

Energy Technology Data Exchange (ETDEWEB)

Huang, Hongxia, E-mail: hhxhunan@yahoo.com.cn [College of Chemistry and Bioengineering, Guilin University of Technology, Guilin (China); Huang, Kelong [College of Chemistry and Chemical Engineering, Central South University (China)

2012-05-15

The influence of surface treatment by solutions of NH{sub 4}F, LiF and LiF containing KBH{sub 4} on the structure and electrochemical properties of the M1Ni{sub 3.5}Co{sub 0.6}Mn{sub 0.4}Al{sub 0.5} hydrogen storage alloy (in which M1 denotes mischmetal) is investigated. The fluorination treatment improves the electrochemical performances of the M1Ni{sub 3.5}Co{sub 0.6}Mn{sub 0.4}Al{sub 0.5} alloy. The maximum discharge capacity (C{sub max}) increases from 314.8 to 325.7 (NH{sub 4}F), 326.5 (LiF) and 316.4 mAh g{sup -1} (LiF+KBH{sub 4}). After 60 cycles, the capacity retention rate increases from 83.5 to 84.8% (NH{sub 4}F), 89.5% (LiF) and 93.9% (LiF+KBH{sub 4}). The results of the linear polarization and anodic polarization reveal that the exchange current density (I{sub 0}) and the limiting current density (I{sub L}) increase after fluorination treatment, indicating an improvement of the kinetics of the hydrogen absorption/desorption. (author)

The role of radiation damage on retention and temperature intervals of helium and hydrogen detrapping in structural materials

Energy Technology Data Exchange (ETDEWEB)

Tolstolutskaya, G.D., E-mail: g.d.t@kipt.kharkov.ua [National Science Center “Kharkov Institute of Physics and Technology”, 1, Akademicheskaya St., 61108 Kharkov (Ukraine); Ruzhytskyi, V.V.; Voyevodin, V.N.; Kopanets, I.E.; Karpov, S.A.; Nikitin, A.V. [National Science Center “Kharkov Institute of Physics and Technology”, 1, Akademicheskaya St., 61108 Kharkov (Ukraine)

2013-11-15

An experimental study of hydrogen/deuterium behavior in ferritic–martensitic stainless steels EP-450 (Cr13Mo2NbVB), EP-852 (Cr13Mo2VS), and RUSFER-EK-181 (Fe12Cr2WVTaB) is presented. The effect of displacement damage (dpa) resulting from irradiation with helium, hydrogen, and argon ions on features of deuterium detrapping and retention in steels was studied using ion implantation, nuclear reaction depth profiling, and thermal desorption spectrometry techniques. Numerical simulation on the basis of the continuum rate theory was applied for obtaining thermodynamic parameters of deuterium trapping and desorption in steels.

First principle investigations of the physical properties of hydrogen-rich MgH2

KAUST Repository

Zarshenas, Mohammed

2013-11-28

Hydrogen being a cleaner energy carrier has increased the importance of hydrogen-containing light metal hydrides, in particular those with large gravimetric hydrogen density like magnesium hydride (MgH2). In this study, density functional and density functional perturbation theories are combined to investigate the structural, elastic, thermodynamic, electronic and optical properties of MgH2. Our structural parameters calculated with those proposed by Perdew, Burke and Ernzerof generalized gradient approximation (PBE-GGA) and Wu-Cohen GGA (WC-GGA) are in agreement with experimental measurements, however the underestimated band gap values calculated using PBE-GGA and WC-GGA were greatly improved with the GGA suggested by Engle and Vosko and the modified Becke-Johnson exchange correlation potential by Trans and Blaha. As for the thermodynamic properties the specific heat values at low temperatures were found to obey the T3 rule and at higher temperatures Dulong and Petit\\'s law. Our analysis of the optical properties of MgH2 also points to its potential application in optoelectronics. © 2013 The Royal Swedish Academy of Sciences.

First principle investigations of the physical properties of hydrogen-rich MgH2

KAUST Repository

Zarshenas, Mohammed; Ahmed, Rashid; Kanoun, Mohammed; Ul Haq, Bakhtiar; Isa, Ahmad Radzi Mat; Goumri-Said, Souraya

2013-01-01

Hydrogen being a cleaner energy carrier has increased the importance of hydrogen-containing light metal hydrides, in particular those with large gravimetric hydrogen density like magnesium hydride (MgH2). In this study, density functional and density functional perturbation theories are combined to investigate the structural, elastic, thermodynamic, electronic and optical properties of MgH2. Our structural parameters calculated with those proposed by Perdew, Burke and Ernzerof generalized gradient approximation (PBE-GGA) and Wu-Cohen GGA (WC-GGA) are in agreement with experimental measurements, however the underestimated band gap values calculated using PBE-GGA and WC-GGA were greatly improved with the GGA suggested by Engle and Vosko and the modified Becke-Johnson exchange correlation potential by Trans and Blaha. As for the thermodynamic properties the specific heat values at low temperatures were found to obey the T3 rule and at higher temperatures Dulong and Petit's law. Our analysis of the optical properties of MgH2 also points to its potential application in optoelectronics. © 2013 The Royal Swedish Academy of Sciences.

Enhanced hydrogen reaction kinetics of nanostructured Mg-based composites with nanoparticle metal catalysts dispersed on supports

International Nuclear Information System (INIS)

Yoo, Yeong; Tuck, Mark; Kondakindi, Rajender; Seo, Chan-Yeol; Dehouche, Zahir; Belkacemi, Khaled

2007-01-01

Hydrogen reaction kinetics of nanocrystalline MgH 2 co-catalyzed with Ba 3 (Ca 1+x Nb 2-x )O 9-δ (BCN) proton conductive ceramics and nanoparticle bimetallic catalyst of Ni/Pd dispersed on single wall carbon nanotubes (SWNTs) support has been investigated. The nanoparticle bimetallic catalysts of Ni/Pd supported by SWNTs were synthesized based on a novel polyol method using NiCl 2 .6H 2 O, PdCl 2 , NaOH and ethylene glycol (EG). The nanostructured Mg composites co-catalyzed with BCN and bimetallic supported catalysts exhibited stable hydrogen desorption capacity of 6.3-6.7 wt.% H 2 and the significant enhancement of hydrogen desorption kinetics at 230-300 deg. C in comparison to either non-catalyzed MgH 2 or the nanocomposite of MgH 2 catalyzed with BCN

Desorption of intrinsic cesium from smectite: inhibitive effects of clay particle organization on cesium desorption.

Science.gov (United States)

Fukushi, Keisuke; Sakai, Haruka; Itono, Taeko; Tamura, Akihiro; Arai, Shoji

2014-09-16

Fine clay particles have functioned as transport media for radiocesium in terrestrial environments after nuclear accidents. Because radiocesium is expected to be retained in clay minerals by a cation-exchange reaction, ascertaining trace cesium desorption behavior in response to changing solution conditions is crucially important. This study systematically investigated the desorption behavior of intrinsic Cs (13 nmol/g) in well-characterized Na-montmorillonite in electrolyte solutions (NaCl, KCl, CaCl2, and MgCl2) under widely differing cation concentrations (0.2 mM to 0.2 M). Batch desorption experiments demonstrated that Cs(+) desorption was inhibited significantly in the presence of the environmental relevant concentrations of Ca(2+) and Mg(2+) (>0.5 mM) and high concentrations of K(+). The order of ability for Cs desorption was Na(+) = K(+) > Ca(2+) = Mg(2+) at the highest cation concentration (0.2 M), which is opposite to the theoretical prediction based on the cation-exchange selectivity. Laser diffraction grain-size analyses revealed that the inhibition of Cs(+) desorption coincided with the increase of the clay tactoid size. Results suggest that radiocesium in the dispersed fine clay particles adheres on the solid phase when the organization of swelling clay particles occurs because of changes in solution conditions caused by both natural processes and artificial treatments.

On the ways of improving mechanical properties of boiler steels subject to hydrogen effect

International Nuclear Information System (INIS)

Tkachev, V.I.; Litvin, A.K.; Zvezdin, Yu.I.

1975-01-01

The effect of oxygen on the strength properties of boiler steels Kh15M2 and 48TS subjected to heat treatment and preliminary plastic deformation has been studied. It is shown that changes in the strength properties of the steel are determined by the heterogeneity of its structure. Treatment which contributes to homogenization of the metal structure increases the resistance of the steel to detrimental effect of hydrogen. Absorption of hydrogen during cathode polarization at various current densities is shown

Improving the hydrogen storage properties of metal-organic framework by functionalization.

Science.gov (United States)

Xia, Liangzhi; Liu, Qing; Wang, Fengling; Lu, Jinming

2016-10-01

Based on the structure of MOF-808, different substituents were introduced to replace hydrogen atom on the phenyl ring of MOF-808. The GCMC method was used to study the effect of functional groups on the hydrogen storage properties of MOF-808-X (X = -OH, -NO 2 , -CH 3 , -CN, -I). The H 2 uptakes and isosteric heat of adsorption were simulated at 77 K. The results indicate that all these substituents have favorable impact on the hydrogen storage capacity, and -CN is found to be the most promising substituent to improve H 2 uptake. These results may be helpful for the design of MOFs with higher hydrogen storage capacity. Graphical abstract Atomistic structures of MOFs. (a) The structures of MOF-808-X. (b) Model of organic linker. Atom color scheme: C, gray; H, white; O, red; X, palegreen (X = -OH, -NO 2 , -CH 3 , -CN, -I).

Anelastic mechanical loss spectrometry of hydrogen in austenitic stainless steels

International Nuclear Information System (INIS)

Yagodzinskyy, Y.; Andronova, E.; Ivanchenko, M.; Haenninen, H.

2009-01-01

Atomic distribution of hydrogen, its elemental diffusion jumps and its interaction with dislocations in a number of austenitic stainless steels are studied with anelastic mechanical loss (AML) spectrometry in combination with the hydrogen thermal desorption method. Austenitic stainless steels of different chemical composition, namely, AISI 310, AISI 201, and AISI 301LN, as well as LDX 2101 duplex stainless steel are studied to clarify the role of different alloying elements on the hydrogen behavior. Activation analyses of the hydrogen Snoek-like peaks are performed with their decomposition to sets of Gaussian components. Fine structure of the composite hydrogen peaks is analyzed under the assumption that each component corresponds to diffusion transfer of hydrogen between octahedral positions with certain atomic compositions of the nearest neighbouring lattice sites. An additional component originating from hydrogen-dislocation interaction is considered. Binding energies for hydrogen-dislocation interaction are also estimated for the studied austenitic stainless steels.

Synthesis and hydrogen storage of La23Nd7.8Ti1.1Ni33.9Co32.9Al0.65 alloys

Directory of Open Access Journals (Sweden)

Priyanka Meena

2018-04-01

Full Text Available The present work investigates structural and hydrogen storage properties of first time synthesized La23Nd7.8Ti1.1Ni33.9Co32.9Al0.65 alloy by arc melting process and ball milled to get it in nano structure form. XRD analysis of as-prepared alloy showed single phased hexagonal LaNi5-type structure with 52 nm average particle size, which reduces to about 31 nm after hydrogenations. Morphological studies by SEM were undertaken to investigate the effect of hydrogenation of nanostructured alloy. EDX analysis confirmed elemental composition of the as-prepared alloy. Activation energy for hydrogen desorption was studied using TGA analysis and found to be −76.86 kJ/mol. Hydrogenation/dehydrogenation reactions and absorption kinetics were measured at temperature 100 °C. The equilibrium plateau pressure was determined to be 2 bar at 100 °C giving hydrogen storage capacity of about 2.1 wt%. Keywords: Hydrogen storage, La23Nd7.8Ti1.1Ni33.9Co32.9Al0.65 alloy, SEM, EDS, TGA, Hydrogenation/dehydrogenation

Catalytically Enhanced Hydrogen Sorption in Mg-MgH2 by Coupling Vanadium-Based Catalyst and Carbon Nanotubes

Directory of Open Access Journals (Sweden)

Atikah Kadri

2015-06-01

Full Text Available Mg (MgH2-based composites, using carbon nanotubes (CNTs and pre-synthesized vanadium-based complex (VCat as the catalysts, were prepared by high-energy ball milling technique. The synergistic effect of coupling CNTs and VCat in MgH2 was observed for an ultra-fast absorption rate of 6.50 wt. % of hydrogen per minute and 6.50 wt. % of hydrogen release in 10 min at 200 °C and 300 °C, respectively. The temperature programmed desorption (TPD results reveal that coupling VCat and CNTs reduces both peak and onset temperatures by more than 60 °C and 114 °C, respectively. In addition, the presence of both VCat and CNTs reduces the enthalpy and entropy of desorption of about 7 kJ/mol H2 and 11 J/mol H2·K, respectively, as compared to those of the commercial MgH2, which ascribe to the decrease of desorption temperature. From the study of the effect of CNTs milling time, it is shown that partially destroyed CNTs (shorter milling time are better to enhance the hydrogen sorption performance.

Recommended Best Practices for the Characterization of Storage Properties of Hydrogen Storage Materials

Energy Technology Data Exchange (ETDEWEB)

None

2010-03-01

This is a reference guide to common methodologies and protocols for measuring critical performance properties of advanced hydrogen storage materials. It helps users to communicate clearly the relevant performance properties of new materials as they are discovered and tested.

Influence of thermo hydrogen treatment on microstructure and mechanical properties of Ti-5Al-2.5Sn ELI alloy

Directory of Open Access Journals (Sweden)

Ya-fei Ren

2017-01-01

Full Text Available Thermo hydrogen treatment (THT of titanium is a process in which hydrogen is used as a temporary alloying element in titanium alloys. It is an attractive approach for controlling the microstructure and thereby improving the final mechanical properties. In the present study, the microstructure of the original (non-hydrogenated sample has only α phase and the grains is coarse with an average size of ~ 650 μm. While the grain size of thermo hydrogen treated Ti-5Al-2.5Sn ELI alloy became finer and the mechanical properties were improved significantly. When the hydrogen content of the hydrogenated Ti-5Al-2.5Sn ELI alloy is 0.321wt.%, β phase and δ titanium hydride appear. Also the average grain size decreases to 450 μm. When the hydrogen content is 0.515wt.%, the grain size decreases to 220 μm. The mechanical properties were tested after dehydrogenation, and the mechanical properties improved significantly compared to the unhydrogenated specimens. The tensile strength of the Ti-5Al-2.5Sn ELI alloy improved by 17.7% when the hydrogen content increased to 0.920wt.%, at the same time the percentage reduction of area (Z increased by 33% and the impact toughness increased by 37%.