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.

Hydrogen Temperature-Programmed Desorption in Platinum Catalysts: Decomposition and Isotopic Exchange by Spillover Hydrogen of Chemisorbed Ammonia.

NARCIS (Netherlands)

Koningsberger, D.C.; Miller, J.T.; Meyers, B.L.; Barr, M.K.; Modica, F.S.

1996-01-01

H{2}-TPD of Pt/alumina catalysts display multiple hydrogendesorptions. In addition to chemisorbed hydrogen (Peak I) atapproximately 175}o{C, there is a small hydrogen desorption (PeakII) at about 250}o{C and a large, irreversible hydrogen desorption(Peak III) at 450}o{C. The quantity of hydrogen

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 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

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

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.

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...

Hydrogen absorption-desorption properties of UZr0.29 alloy

International Nuclear Information System (INIS)

Shuai Maobing; Su Yongjun; Wang Zhenhong; Zhang Yitao

2001-01-01

Hydrogen absorption-desorption properties of UZr 0.29 alloy are investigated in detail at hydrogen pressures up to 0.4 MPa and over the temperature range of 300 to 723 K. It absorbs hydrogen up to 2.3 H atoms per F.U. (formula unit) by only one-step reaction and hence each desorption isotherm has a single plateau over nearly the whole hydrogen composition range. The enthalpy and entropy changes of the dissociation reaction are of -78.9 kJ·mol -1 H 2 and 205.3 J·(K·mol H 2 ) -1 , respectively. The alloy shows high durability against powdering upon hydrogenation and may have good heat conductivity. It is predicted that UZr 0.29 alloy may be a suitable material for tritium treatment and storage

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

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.

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

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

Hydrogen absorption-desorption properties of U2Ti

International Nuclear Information System (INIS)

Yamamoto, Takuya; Tanaka, Satoru; Yamawaki, Michio

1990-01-01

Hydrogen absorption-desorption properties of U 2 Ti intermetallic compound was examined over the temperature range of 298 to 973 K and at hydrogen pressures below 10 5 Pa. It absorbs hydrogen up to 7.6 atoms per F.U. (formula unit) by two step reactions and hence each desorption isotherm is separated into two plateau regions. In the first plateau, a newly-found ternary hydride is formed, where the hydrogen concentration, c H , reaches 2.4 H atoms/F.U. In the second plateau, UH 3 is formed and c H reaches 7.6 H atoms/F.U. The specimen is disintegrated into fine powder in the second plateau, while in the first plateau the ternary hydride which was identified to be UTi 2 H x (x=4.8 to 6.2) showed high durability against powdering. It is predicted that UTi 2 can be suitable material for tritium storage. (orig.)

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.

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.

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

Thermal desorption and surface modification of He+ implanted into tungsten

International Nuclear Information System (INIS)

Fu Zhang; Yoshida, N.; Iwakiri, H.; Xu Zengyu

2004-01-01

Tungsten divertor plates in fusion reactors will be subject to helium bombardment. Helium retention and thermal desorption is a concerned issue in controlling helium ash. In the present study, fluence dependence of thermal desorption behavior of helium in tungsten was studied at different irradiation temperatures and ion energies. Results showed that helium desorption could start at ∼400 K with increasing fluence, while no noticeable peaks were detected at low fluence. Total helium desorption reached a saturation value at high fluence range, which was not sensitive to irradiation temperature or ion energy for the conditions evaluated. Surface modifications caused by either ion irradiation or thermal desorption were observed by SEM. The relationship of surface modifications and helium desorption behavior was discussed. Some special features of elevated irradiation temperature and lower ion energy were also indicated

Treating high-mercury-containing lamps using full-scale thermal desorption technology.

Science.gov (United States)

Chang, T C; You, S J; Yu, B S; Chen, C M; Chiu, Y C

2009-03-15

The mercury content in high-mercury-containing lamps are always between 400 mg/kg and 200,000 mg/kg. This concentration is much higher than the 260 mg/kg lower boundary recommended for the thermal desorption process suggested by the US Resource Conservation and Recovery Act. According to a Taiwan EPA survey, about 4,833,000 cold cathode fluorescent lamps (CCFLs), 486,000 ultraviolet lamps and 25,000 super high pressure mercury lamps (SHPs) have been disposed of in the industrial waste treatment system, producing 80, 92 and 9 kg-mercury/year through domestic treatment, offshore treatment and air emissions, respectively. To deal with this problem we set up a full-scale thermal desorption process to treat and recover the mercury from SHPs, fluorescent tube tailpipes, fluorescent tubes containing mercury-fluorescent powder, and CCFLs containing mercury-fluorescent powder and monitor the use of different pre-heating temperatures and desorption times. The experimental results reveal that the average thermal desorption efficiency of SHPs and fluorescent tube tailpipe were both 99.95%, while the average thermal desorption efficiencies of fluorescent tubes containing mercury-fluorescent powder were between 97% and 99%. In addition, a thermal desorption efficiency of only 69.37-93.39% was obtained after treating the CCFLs containing mercury-fluorescent powder. These differences in thermal desorption efficiency might be due to the complexity of the mercury compounds contained in the lamps. In general, the thermal desorption efficiency of lamps containing mercury-complex compounds increased with higher temperatures.

Hydrogen desorption properties of MgH2–Ni–Ni2Si composites prepared by mechanochemical method

International Nuclear Information System (INIS)

Shimada, Motoki; Higuchi, Eiji; Inoue, Hiroshi

2013-01-01

Highlights: ► The MgH 2 –Ni composite showed fast hydrogen desorption rate at 250 °C. ► The MgH 2 –Ni–Ni 2 Si composite showed fast hydrogen desorption rate at 220 °C. ► Nanocrystalline Mg 2 Ni and Mg 2 Si were formed between Mg and adjacent Ni or Si. ► Ni 2 Si did not form any alloys and work as a catalyst. -- Abstract: To improve hydrogen desorbability of Mg, some composites were prepared from MgH 2 , Ni and Ni 2 Si mixed powders by the mechanochemical method. The MgH 2 –Ni(2 mol%)–Ni 2 Si(1 mol%) composite was slower in hydrogen desorption rate at 250 °C than the MgH 2 –Ni(2 mol%) composite, while the hydrogen desorption rate at 220 °C for the former was faster than that for the latter. The XRD pattern of the MgH 2 –Ni(2 mol%) composite showed that after hydrogen desorption at 400 °C small diffraction peaks assigned to Mg 2 Ni were observed with peaks assigned to Mg. They shifted to smaller angles after hydrogen absorption at 250 °C and come back to the original positions after hydrogen desorption at 250 °C, suggesting reversible hydrogen absorption/desorption of Mg 2 Ni. In contrast, Ni 2 Si was not changed over the whole processes. These results indicated that Ni 2 Si worked as a catalyst for hydrogen desorption, leading to the improvement of desorbability at 220 °C

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

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

Thermal desorption study of physical forces at the PTFE surface

Science.gov (United States)

Wheeler, D. R.; Pepper, S. V.

1987-01-01

Thermal desorption spectroscopy (TDS) of the polytetrafluoroethylene (PTFE) surface was successfully employed to study the possible role of physical forces in the enhancement of metal-PTFE adhesion by radiation. The thermal desorption spectra were analyzed without assumptions to yield the activation energy for desorption over a range of xenon coverage from less than 0.1 monolayer to more than 100 monolayers. For multilayer coverage, the desorption is zero-order with an activation energy equal to the sublimation energy of xenon. For submonolayer coverages, the order for desorption from the unirradiated PTFE surface is 0.73 and the activation energy for desorption is between 3.32 and 3.36 kcal/mol; less than the xenon sublimation energy. The effect of irradiation is to increase the activation energy for desorption to as high as 4 kcal/mol at low coverage.

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)

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.

Non-thermal desorption from interstellar dust grains via exothermic surface reactions

Science.gov (United States)

Garrod, R. T.; Wakelam, V.; Herbst, E.

2007-06-01

Aims:The gas-phase abundance of methanol in dark quiescent cores in the interstellar medium cannot be explained by gas-phase chemistry. In fact, the only possible synthesis of this species appears to be production on the surfaces of dust grains followed by desorption into the gas. Yet, evaporation is inefficient for heavy molecules such as methanol at the typical temperature of 10 K. It is necessary then to consider non-thermal mechanisms for desorption. But, if such mechanisms are considered for the production of methanol, they must be considered for all surface species. Methods: Our gas-grain network of reactions has been altered by the inclusion of a non-thermal desorption mechanism in which the exothermicity of surface addition reactions is utilized to break the bond between the product species and the surface. Our estimated rate for this process derives from a simple version of classical unimolecular rate theory with a variable parameter only loosely constrained by theoretical work. Results: Our results show that the chemistry of dark clouds is altered slightly at times up to 106 yr, mainly by the enhancement in the gas-phase abundances of hydrogen-rich species such as methanol that are formed on grain surfaces. At later times, however, there is a rather strong change. Instead of the continuing accretion of most gas-phase species onto dust particles, a steady-state is reached for both gas-phase and grain-surface species, with significant abundances for the former. Nevertheless, most of the carbon is contained in an undetermined assortment of heavy surface hydrocarbons. Conclusions: The desorption mechanism discussed here will be better constrained by observational data on pre-stellar cores, where a significant accretion of species such as CO has already occurred.

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...

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.

Spatially resolved thermal desorption/ionization coupled with mass spectrometry

Science.gov (United States)

Jesse, Stephen; Van Berkel, Gary J; Ovchinnikova, Olga S

2013-02-26

A system and method for sub-micron analysis of a chemical composition of a specimen are described. The method includes providing a specimen for evaluation and a thermal desorption probe, thermally desorbing an analyte from a target site of said specimen using the thermally active tip to form a gaseous analyte, ionizing the gaseous analyte to form an ionized analyte, and analyzing a chemical composition of the ionized analyte. The thermally desorbing step can include heating said thermally active tip to above 200.degree. C., and positioning the target site and the thermally active tip such that the heating step forms the gaseous analyte. The thermal desorption probe can include a thermally active tip extending from a cantilever body and an apex of the thermally active tip can have a radius of 250 nm or less.

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.

The Design and Development of Enhanced Thermal Desorption Products

Directory of Open Access Journals (Sweden)

R. Humble

2005-01-01

Full Text Available This research study is based on a knowledge-transfer collaboration between The National Centre for Product Design and Development Research (PDR and Markes International Ltd. The aim of the two-year collaboration has been to implement design tools and techniques for the development of enhanced thermal desorption products. Thermal desorption is a highly-specialised technique for the analysis of trace-level volatile organic compounds. This technique allows minute quantities of these compounds to be measured; however, there is an increasing demand from customers for greater sensitivity over a wider range of applications, which means new design methodologies need to be evaluated. The thermal desorption process combines a number of disparate chemical, thermal and mechanical disciplines, and the major design constraints arise from the need to cycle the sample through extremes in temperature. Following the implementation of a comprehensive product design specification, detailed design solutions have been developed using the latest 3D CAD techniques. The impact of the advanced design techniques is assessed in terms of improved product performance and reduced development times, and the wider implications of new product development within small companies are highlighted.  

Effect of long-term hydrogen absorption/desorption cycling on hydrogen storage properties of MmNi3.55Co0.75Mn0.4Al0.3

International Nuclear Information System (INIS)

Li, S.L.; Chen, W.; Chen, D.M.; Yang, K.

2009-01-01

The effect of a long-term hydrogen absorption/desorption cycling up to 2000 cycles on the hydrogen storage properties of MmNi 3.55 Co 0.75 Mn 0.4 Al 0.3 alloy was investigated. The pressure-composition (PC) isotherms for absorption/desorption and absorption kinetics were measured at 338 K, 353 K and 368 K both after initial activation and 2000 cycles. X-ray diffraction analysis revealed that the alloy had a homogeneous hexagonal CaCu 5 type structure and kept this structure even after 2000 hydrogen absorption/desorption cycles. It is found that the absorption/desorption plateau pressures were lowered, the storage capacity and the absorption kinetics were slightly degraded and the hysteresis loss was increased at all the investigated temperatures after 2000 cycles. It is also found that the particle size after 2000 cycles was much smaller compared to that after initial activation. The change of the hydrogen absorption/desorption properties of the alloy after 2000 cycles has been explained by considering the crystal structure, disproportionation property, pulverization of the sample and the impurities in the charging hydrogen employed in cycling

Property changes of some hydrogen storage alloys upon hydrogen absorption-desorption cycling

International Nuclear Information System (INIS)

Park, C.N.; Cho, S.W.; Choi, J.

2005-01-01

Hydrogen absorption-desorption cycling induced by pressure change in a closed system were carried out with LaNi 5 , La 0.7 Ce 0.3 Ni 4 Cu and TiFe 0.9 Ni 0.1 alloys. PC isotherms measured during the cycling showed some changes in hydrogen storage capacity, plateau pressure and hysteresis of the alloys. The half capacity life of LaNi 5 alloy can be projected as 70,000 cycles for room temperature pressure cycling. When La 0.7 Ce 0.3 Ni 4 Cu alloy was pressure cycled both of the plateau pressures were decreased significantly and continuously. TiFe 0.9 Ni 0.1 alloy showed a good resistance to cyclic degradation. Heat treatments of the degraded alloys under 1 atm of hydrogen gas recovered most of the hydrogen storage properties to the initial level even though they were degraded again more rapidly upon subsequent cycling. (orig.)

Insight to the Thermal Decomposition and Hydrogen Desorption Behaviors of NaNH2-NaBH4 Hydrogen Storage Composite.

Science.gov (United States)

Pei, Ziwei; Bai, Ying; Wang, Yue; Wu, Feng; Wu, Chuan

2017-09-20

The lightweight compound material NaNH 2 -NaBH 4 is regarded as a promising hydrogen storage composite due to the high hydrogen density. Mechanical ball milling was employed to synthesize the composite NaNH 2 -NaBH 4 (2/1 molar ratio), and the samples were investigated utilizing thermogravimetric-differential thermal analysis-mass spectroscopy (TG-DTA-MS), X-ray diffraction (XRD), and Fourier transform infrared spectroscopy (FTIR) analyses. The full-spectrum test (range of the ratio of mass to charge: 0-200) shows that the released gaseous species contain H 2 , NH 3 , B 2 H 6 , and N 2 in the heating process from room temperature to 400 °C, and possibly the impurity gas B 6 H 12 also exists. The TG/DTA analyses show that the composite NaNH 2 -NaBH 4 (2/1 molar ratio) is conductive to generate hydrogen so that the dehydrogenation process can be finished before 400 °C. Moreover, the thermal decomposition process from 200 to 400 °C involves two-step dehydrogenation reactions: (1) Na 3 (NH 2 ) 2 BH 4 hydride decomposes into Na 3 BN 2 and H 2 (200-350 °C); (2) remaining Na 3 (NH 2 ) 2 BH 4 reacts with NaBH 4 and Na 3 BN 2 , generating Na, BN, NH 3 , N 2 , and H 2 (350-400 °C). The better mechanism understanding of the thermal decomposition pathway lays a foundation for tailoring the hydrogen storage performance of the composite complex hydrides system.

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%.

Gas desorption properties of ammonia borane and metal hydride composites

International Nuclear Information System (INIS)

Matin, M.R.

2009-01-01

'Full text': Ammonia borane (NH 3 BH 3 ) has been of great interest owing to its ideal combination of low molecular weight and high H 2 storage capacity of 19.6 mass %, which exceeds the current capacity of gasoline. DOE's year 2015 targets involve gravimetric as well as volumetric energy densities. In this work, we have investigated thermal decomposition of ammonia borane and calcium hydride composites at different molar ratio. The samples were prepared by planetary ball milling under hydrogen gas atmosphere pressure of 1Mpa at room temperature for 2, and 10 hours. The gas desorption properties were examined by thermal desorption mass spectroscopy (TDMS). The identification of phases was carried out by X-ray diffraction. The results obtain were shown in fig (a),(b),and (c). Hydrogen desorption properties were observed at all molar ratios, but the desorption temperature is significantly lower at around 70 o C at molar ratio 1:1 as shown in fig (c), and unwanted gas (ammonia) emissions were remarkably suppressed by mixing with the calcium hydride. (author)

Impact of neutron irradiation on thermal helium desorption from iron

Energy Technology Data Exchange (ETDEWEB)

Hu, Xunxiang, E-mail: hux1@ornl.gov [Oak Ridge National Laboratory, Oak Ridge, TN 37831 (United States); Field, Kevin G. [Oak Ridge National Laboratory, Oak Ridge, TN 37831 (United States); Taller, Stephen [University of Michigan, Ann Arbor, MI 48109 (United States); Katoh, Yutai [Oak Ridge National Laboratory, Oak Ridge, TN 37831 (United States); Wirth, Brian D. [Oak Ridge National Laboratory, Oak Ridge, TN 37831 (United States); University of Tennessee, Knoxville, TN 37996 (United States)

2017-06-15

The synergistic effect of neutron irradiation and transmutant helium production is an important concern for the application of iron-based alloys as structural materials in fission and fusion reactors. In this study, we investigated the impact of neutron irradiation on thermal helium desorption behavior in high purity iron. Single crystalline and polycrystalline iron samples were neutron irradiated in HFIR to 5 dpa at 300 °C and in BOR-60 to 16.6 dpa at 386 °C, respectively. Following neutron irradiation, 10 keV He ion implantation was performed at room temperature on both samples to a fluence of 7 × 10{sup 18} He/m{sup 2}. Thermal desorption spectrometry (TDS) was conducted to assess the helium diffusion and clustering kinetics by analyzing the desorption spectra. The comparison of He desorption spectra between unirradiated and neutron irradiated samples showed that the major He desorption peaks shift to higher temperatures for the neutron-irradiated iron samples, implying that strong trapping sites for He were produced during neutron irradiation, which appeared to be nm-sized cavities through TEM examination. The underlying mechanisms controlling the helium trapping and desorption behavior were deduced by assessing changes in the microstructure, as characterized by TEM, of the neutron irradiated samples before and after TDS measurements.

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

We present the theoretical and experimental developments made to study the desorption of hydrogen from metallic samples by Thermal Desorption Spectroscopy (TDS). With this technique gas desorption is stimulated by the programmed heating of the sample. To perform the study we set up a newly designed equipment and develop theoretical models of the kinetic processes involved. The equipment and the models are used to analyze the desorption process in a real system. We begin by analyzing the models developed to interpret the results of the experiments. These models considersimultaneously bulk diffusion and surface reaction processes in metal-hydrogen systems with one or two thermodynamic phases. We present numerical results, computer simulations and analytical approximations of the original models. Based on these results we analyze the main features of the spectra for the different relevant kinetic processes, and determine the changes induced in them when material parameters (activation energies, geometry) or experimental parameters (heating speed, initial concentration) are modified.We present the original equipment, designed and constructed during this work to perform the TDS experiments. We describe its main characteristics, its components, its range of operation and its sensibility. We also offer an analysis of the background spectrum. We use the Pd-H system to test the equipment and the models. The samples chosen, powders, granules, foils and wires, were previously characterized to analyze their composition, their morphology and their characteristic size. We show the results of Scanning Electron Microscopy (SEM) observation, X ray diffraction (XRD) and Auger Electron Spectroscopy (AES) analysis.We then present and analyze in depth the experimental desorption spectra of the palladium powder. Based on the analysis we determine the rate limiting step for desorption and the characteristic activation energies. When the system is on the b phase (hydride) the rate

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

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.

Hydrogen retention properties of lithium film

International Nuclear Information System (INIS)

Kanaya, Koh; Yamauchi, Yuji; Hirohata, Yuko; Hino, Tomoaki; Mori, Kintaro

1998-01-01

Hydrogen retention properties of Li films and lithium oxide-lithium hydroxide (Li 2 O-LiOH) mixed films were investigated by two methods, hydrogen ion irradiation and hydrogen glow discharge. In a case of the hydrogen ion irradiation, thermal desorption spectrum of hydrogen retained in Li 2 O-LiOH film had two desorption peaks at around 470 K and 570 K. The ratio between retained hydrogen and Li atom was about 0.7. In a case of the hydrogen glow discharge, the hydrogen was also gettered in Li film during the discharge. The ratio of H/Li was almost 0.9. Most of gettered hydrogen desorbed by a baking with a temperature of 370 K. On the contrary, when the Li film exposed to the atmosphere was irradiated by the hydrogen plasma, the desorption of H 2 O was observed in addition to the adsorption of H 2 . (author)

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.

Study of defects near molybdenum surface using thermal desorption spectrometer

International Nuclear Information System (INIS)

Naik, P.K.

1980-01-01

Thermal desorption spectrometry is utilized to study the migration of atoms and defects near molybdenum surface. The thermal desorption spectra of inert gas ions (neon, argon and krypton) injected with various energies (430-1950 eV) into a polycrystalline molybdenum target with various dosages (6.4 x 10sup(12) - 3.9 x 10sup(14) ions/cmsup(2)) are investigated. Four different states of binding of the trapped atoms corresponding to the activation energies for desorption have been revealed from the spectra. The activation energies are found to be relatively insensitive to the species of the bombarding ion, incident ion energy and the dosage. The patterns of the spectra are strongly influenced by the mean projected range of the ions into the solid. The activation energies deduced are in good agreement with those reported for the migration of atoms and defects in molybdenum. (auth.)

Changes of structural and hydrogen desorption properties of MgH2 indused by ion irradiation

Directory of Open Access Journals (Sweden)

Kurko Sandra V.

2010-01-01

Full Text Available Changes in structural and hydrogen desorption properties of MgH2 induced by ion irradiation have been investigated. MgH2 powder samples have been irradiated with 45 keV B3+ and 120 keV Ar8+ions, with ion fluence of 1015 ions/cm2. The effects of ion irradiation are estimated by numerical calculations using SRIM package. The induced material modifications and their consequences on hydrogen dynamics in the system are investigated by XRD, particle size distribution and TPD techniques. Changes of TPD spectra with irradiation conditions suggest that there are several mechanisms involved in desorption process which depend on defect concentration and their interaction and ordering. The results confirmed that the near-surface area of MgH2 and formation of a substoichiometric MgHx (x<2 play a crucial role in hydrogen kinetics and that various concentrations of induced defects substantially influence H diffusion and desorption kinetics in MgH2. The results also confirm that there is possibility to control the thermodynamic parameters by controlling vacancies concentration in the system.

Rapid screening of pharmaceutical drugs using thermal desorption – SALDI mass spectrometry

International Nuclear Information System (INIS)

Grechnikov, A A; Kubasov, A E; Borodkov, A S; Georgieva, V B; Nikiforov, S M; Simanovsky, Ya O; Alimpiev, S S

2012-01-01

A novel approach to the rapid screening of pharmaceutical drugs by surface assisted laser desorption-ionization (SALDI) mass spectrometry with the rotating ball interface coupled with temperature programmed thermal desorption has been developed. Analytes were thermally desorbed and deposited onto the surface of amorphous silicon substrate attached to the rotating ball. The ball was rotated and the deposited analytes were analyzed using SALDI. The effectiveness of coupling SALDI mass spectrometry with thermal desorption was evaluated by the direct and rapid analysis of tablets containing lidocaine, diphenhydramine and propranolol without any sample pretreatment. The overall duration of the screening procedure was 30÷40 sec. Real urine samples were studied for drug analysis. It is shown that with simple preparation steps, urine samples can be quantitatively analyzed using the proposed technique with the detection limits in the range of 0.2÷0.5 ng/ml.

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).

Comparison of a disposable sorptive sampler with thermal desorption in a gas chromatographic inlet, or in a dedicated thermal desorber, to conventional stir bar sorptive extraction-thermal desorption for the determination of micropollutants in water.

Science.gov (United States)

Wooding, Madelien; Rohwer, Egmont R; Naudé, Yvette

2017-09-01

The presence of micropollutants in the aquatic environment is a worldwide environmental concern. The diversity of micropollutants and the low concentration levels at which they may occur in the aquatic environment have greatly complicated the analysis and detection of these chemicals. Two sorptive extraction samplers and two thermal desorption methods for the detection of micropollutants in water were compared. A low-cost, disposable, in-house made sorptive extraction sampler was compared to SBSE using a commercial Twister sorptive sampler. Both samplers consisted of polydimethylsiloxane (PDMS) as a sorptive medium to concentrate micropollutants. Direct thermal desorption of the disposable samplers in the inlet of a GC was compared to conventional thermal desorption using a commercial thermal desorber system (TDS). Comprehensive gas chromatography coupled to time-of-flight mass spectrometry (GC × GC-TOFMS) was used for compound separation and identification. Ten micropollutants, representing a range of heterogeneous compounds, were selected to evaluate the performance of the methods. The in-house constructed sampler, with its associated benefits of low-cost and disposability, gave results comparable to commercial SBSE. Direct thermal desorption of the disposable sampler in the inlet of a GC eliminated the need for expensive consumable cryogenics and total analysis time was greatly reduced as a lengthy desorption temperature programme was not required. Limits of detection for the methods ranged from 0.0010 ng L -1 to 0.19 ng L -1 . For most compounds, the mean (n = 3) recoveries ranged from 85% to 129% and the % relative standard deviation (% RSD) ranged from 1% to 58% with the majority of the analytes having a %RSD of less than 30%. Copyright © 2017 Elsevier B.V. All rights reserved.

Kinetics Study of Gas Pollutant Adsorption and Thermal Desorption on Silica Gel

Directory of Open Access Journals (Sweden)

Rong A

2017-06-01

Full Text Available Silica gel is a typical porous desiccant material. Its adsorption performance for gaseous air pollutants was investigated to determine its potential contribution to reducing such pollutants. Three gaseous air pollutants, toluene, carbon dioxide, and methane, were investigated in this paper. A thermogravimetric analyzer was used to obtain the equilibrium adsorption capacity of gases on single silica gel particles. The silica gel adsorption capacity for toluene is much higher than that for carbon dioxide and methane. To understand gas pollutant thermal desorption from silica gel, the thermogravimetric analysis of toluene desorption was conducted with 609 ppm toluene vapor at 313 K, 323 K, and 333 K. The overall regeneration rate of silica gel was strongly dependent on temperature and the enthalpy of desorption. The gas pollutant adsorption performance and thermal desorption on silica gel material may be used to estimate the operating and design parameters for gas pollutant adsorption by desiccant wheels.

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

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.)

Modelling deuterium release during thermal desorption of D{sup +}-irradiated tungsten

Energy Technology Data Exchange (ETDEWEB)

Poon, M. [University of Toronto Institute for Aerospace Studies, Toronto, ON, M3H 5T6 (Canada); Haasz, A.A. [University of Toronto Institute for Aerospace Studies, Toronto, ON, M3H 5T6 (Canada)], E-mail: tonyhaasz@utias.utoronto.ca; Davis, J.W. [University of Toronto Institute for Aerospace Studies, Toronto, ON, M3H 5T6 (Canada)

2008-03-15

Thermal desorption profiles were modelled based on SIMS measurements of implantation profiles and using the multi-trap diffusion code TMAP7 [G.R. Longhurst, TMAP7: Tritium Migration Analysis Program, User Manual, Idaho National Laboratory, INEEL/EXT-04-02352 (2004)]. The thermal desorption profiles were the result of 500 eV/D{sup +} irradiations on single crystal tungsten at 300 and 500 K to fluences of 10{sup 22}-10{sup 24} D{sup +}/m{sup 2}. SIMS depth profiling was performed after irradiation to obtain the distribution of trapped D within the top 60 nm of the surface. Thermal desorption spectroscopy (TDS) was performed subsequently to obtain desorption profiles and to extract the total trapped D inventory. The SIMS profiles were calibrated to give D concentrations. To account for the total trapped D inventory measured by TDS, SIMS depth distributions were used in the near-surface (surface to 30 nm), NRA measurements [V.Kh. Alimov, J. Roth, M. Mayer, J. Nucl. Mater. 337-339 (2005) 619] were used in the range 1-7 {mu}m, and a linear drop in the D distribution was assumed in the intermediate sub-surface region ({approx}30 nm to 1 {mu}m). Traps were assumed to be saturated so that the D distribution also represented the trap distribution. Three trap energies, 1.07 {+-} 0.03, 1.34 {+-} 0.03 and 2.1 {+-} 0.05 eV were required to model the 520, 640 and 900 K desorption peaks, respectively. The 1.34 and 1.07 eV traps correspond to trapping of a first and second D atom at a vacancy, respectively, while the 2.1 eV trap corresponds to atomic D trapping at a void. A fourth trap energy of 0.65 eV was used to fit the 400 K desorption peak observed by Quastel et al. [A.D. Quastel, J.W. Davis, A.A. Haasz, R.G. Macaulay-Newcombe, J. Nucl. Mater. 359 (2006) 8].

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...

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.

Organic and inorganic decomposition products from the thermal desorption of atmospheric particles

Science.gov (United States)

Williams, Brent J.; Zhang, Yaping; Zuo, Xiaochen; Martinez, Raul E.; Walker, Michael J.; Kreisberg, Nathan M.; Goldstein, Allen H.; Docherty, Kenneth S.; Jimenez, Jose L.

2016-04-01

Atmospheric aerosol composition is often analyzed using thermal desorption techniques to evaporate samples and deliver organic or inorganic molecules to various designs of detectors for identification and quantification. The organic aerosol (OA) fraction is composed of thousands of individual compounds, some with nitrogen- and sulfur-containing functionality and, often contains oligomeric material, much of which may be susceptible to decomposition upon heating. Here we analyze thermal decomposition products as measured by a thermal desorption aerosol gas chromatograph (TAG) capable of separating thermal decomposition products from thermally stable molecules. The TAG impacts particles onto a collection and thermal desorption (CTD) cell, and upon completion of sample collection, heats and transfers the sample in a helium flow up to 310 °C. Desorbed molecules are refocused at the head of a gas chromatography column that is held at 45 °C and any volatile decomposition products pass directly through the column and into an electron impact quadrupole mass spectrometer. Analysis of the sample introduction (thermal decomposition) period reveals contributions of NO+ (m/z 30), NO2+ (m/z 46), SO+ (m/z 48), and SO2+ (m/z 64), derived from either inorganic or organic particle-phase nitrate and sulfate. CO2+ (m/z 44) makes up a major component of the decomposition signal, along with smaller contributions from other organic components that vary with the type of aerosol contributing to the signal (e.g., m/z 53, 82 observed here for isoprene-derived secondary OA). All of these ions are important for ambient aerosol analyzed with the aerosol mass spectrometer (AMS), suggesting similarity of the thermal desorption processes in both instruments. Ambient observations of these decomposition products compared to organic, nitrate, and sulfate mass concentrations measured by an AMS reveal good correlation, with improved correlations for OA when compared to the AMS oxygenated OA (OOA

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

Thermal desorption of deuterium from modified carbon nanotubes and its correlation to the microstructure

NARCIS (Netherlands)

Lisowski, W.F.; Keim, Enrico G.; van den Berg, A.H.J.; Smithers, Mark A.; Smithers, M.A.

2006-01-01

The process of deuterium desorption from single-wall carbon nanotubes (SWNTs) modified by atomic (D) and molecular (D2) deuterium treatment was investigated in an ultrahigh vacuum environment using thermal desorption mass spectroscopy (TDMS). Microstructural and chemical analyses of SWNT material,

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.

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.

Experimental Study on Methane Desorption from Lumpy Coal under the Action of Hydraulic and Thermal

Directory of Open Access Journals (Sweden)

Dong Zhao

2018-01-01

Full Text Available Moisture and thermal are the key factors for influencing methane desorption during CBM exploitation. Using high-pressure water injection technology into coalbed, new fractures and pathways are formed to transport methane. A phenomenon of water-inhibiting gas flow existed. This study is focused on various water pressures impacted on gas-adsorbed coal samples, and then the desorption capacity could be revealed under different conditions. And the results are shown that methane desorption capacity was decreased with the increase in water pressure at room temperature and the downtrend would be steady until water pressure was large enough. Heating could promote gas desorption capacity effectively, with the increasing of water injection pressures, and the promotion of thermal on desorption became more obvious. These results are expected to provide a clearer understanding of theoretical efficiency of heat water or steam injection into coalbed, and they can provide some theoretical and experimental guidance on CBM production and methane control.

Solid Waste Decontamination by Thermal Desorption and Catalytic Oxidation Methods

Czech Academy of Sciences Publication Activity Database

Šolcová, Olga; Topka, Pavel; Soukup, Karel; Jirátová, Květa; Váňová, H.; Kaštánek, František

2014-01-01

Roč. 68, č. 9 (2014), s. 1279-1282 ISSN 0366-6352 R&D Projects: GA MPO FR-TI1/059 Institutional support: RVO:67985858 Keywords : thermal desorption * catalytic oxidation * soil decontamination Subject RIV: CI - Industrial Chemistry, Chemical Engineering Impact factor: 1.468, year: 2014

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

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.

Treatment of Y-12 storm sewer sediments and DARA soils by thermal desorption

International Nuclear Information System (INIS)

Morris, M.I.; Shealy, S.E.

1995-01-01

The 1992 Oak Ridge Reservation Federal Facilities Compliance Agreement (FFCA) listed a number of mixed wastes, subject to land disposal restrictions (LDR), for which no treatment method had been identified, and required DOE to develop strategies for treatment and ultimate disposal of those wastes. This paper presents the results of a program to demonstrate that thermal desorption can remove both organics and mercury from two mixed wastes from the DOE Y-12 facility in Oak Ridge, Tennessee. The first waste, the Y-12 Storm Sewer Sediments (SSSs) was a sediment generated from upgrades to the plant storm sewer system. This material contained over 4 percent mercury, 2 percent uranium and 350 mg/kg polychlorinated biphenyls (PCBs). Leachable mercury exceeded toxicity characteristic leaching procedure (TCLP) and LDR criteria. The second waste, the Disposal Area Remedial Action (DARA) Soils, are contaminated with uranium, mercury and PCBs. This treatability study included bench-scale testing of a thermal desorption process. Results of the testing showed that, for the SSSs, total mercury could be reduced to 120 mg/kg by treatment at 600 degrees C, which is at the high end of the temperature range for typical thermal desorption systems. Leachable TCLP mercury was less than 50 μg/L and PCBs were below 2 mg/kg. Treatment of the DARA Soils at 450 degrees C for 10 minutes resulted in residual PCBs of 0.6 to 3.0 mg/kg. This is too high (goal < 2mg/kg) and higher treatment temperatures are needed. The testing also provided information on the characteristics and quantities of residuals from the thermal desorption process

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.

Case study of manufactured gas plant site remediations using thermal desorption

Energy Technology Data Exchange (ETDEWEB)

Vogel, R.G.; Hayes, T.; Slimon, K.F.; Unites, D. [Southern California Gas Company, Los Angeles, CA (United States)

1995-12-31

Southern California Gas Company (SoCal Gas) has recently remediated five of its former manufactured gas plant (MGP) sites using on-site and off-site thermal desorption. This technology has proven effective in the treatment of PAH-contaminated soils with widely variable concentrations. At two of the five sites, MGP-contaminated materials were excavated and thermally treated on site. At the other sites, MGP-contaminated materials were excavated and transported directly to an off-site thermal desorber. Much of the production was of oil-gas, giving lampblack contamination, but some coal tar was also present.

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...

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.

Thermal desorption spectroscopy of boron/carbon films after keV deuterium irradiation

International Nuclear Information System (INIS)

Yamaki, T.; Gotoh, Y.; Ando, T.; Jimbou, R.; Ogiwara, N.; Saidoh, M.

1994-01-01

Thermal desorption spectroscopy (TDS) of D 2 and CD 4 was done on boron/carbon films (B/(B+C)=0-74%), after 3 keV D 3 + irradiation to 4.5x10 17 D/cm 2 at 473 K. The D 2 desorption peaks were observed at 1050, 850 and 650 K. For a sputter B/C film (0%), only the 1050 K peak was observed. With increasing boron concentration to 3%, a sharp peak appeared at 850 K, the intensity of which was found to increase with increasing boron concentration to 23%, and then to decrease at 74%. The 650 K shoulder, which was observed for high boron concentration specimens, was speculated to be deuterium trapped by boron atoms in the boron clusters. The relative amount of CD 4 desorption was found to decrease with increasing boron concentration, which was attributed to the decrease in the trapped deuterium concentration in the implantation layer at temperatures at which CD 4 desorption proceeds. ((orig.))

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

Decomposition of thin titanium deuteride films: thermal desorption kinetics studies combined with microstructure analysis

NARCIS (Netherlands)

Lisowski, W.F.; Keim, Enrico G.; Kaszkur, Zbigniew; Smithers, M.A.; Smithers, Mark A.

2008-01-01

The thermal evolution of deuterium from thin titanium films, prepared under UHV conditions and deuterated in situ at room temperature, has been studied by means of thermal desorption mass spectrometry (TDMS) and a combination of scanning electron microscopy (SEM), transmission electron microscopy

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.

Thermal desorption of deuterium from polycrystalline nickel pre-implanted with helium

International Nuclear Information System (INIS)

Shi, S.Q.; Abramov, E.; Thompson, D.A.

1990-01-01

The thermal desorption technique has been used to study the trapping of deuterium atoms in high-purity polycrystalline nickel pre-implanted with helium for 1 x 10 19 to 5 x 10 20 ions/m 2 . The effect of post-implantation annealing at 703 K and 923 K on the desorption behavior was investigated. Measured values of the total amount of detrapped deuterium (Q T ) and helium concentration were used in a computer simulation of the desorption curve. It was found that the simulation using one or two discrete trap energies resulted in an inadequate fit between the simulated and the measured data. Both experimental and simulation results are explained using a stress-field trapping model. The effective binding energy, E b eff , was estimated to be in the range of 0.4-0.6 eV. Deuterium charging was found to stimulate a release of helium at a relatively low temperature

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

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

Thermal desorption spectroscopy of pyrolytic graphite cleavage faces after keV deuterium irradiation at 330-1000 K

International Nuclear Information System (INIS)

Gotoh, Y.; Yamaki, T.; Tokiguchi, K.

1992-01-01

Thermal desorption spectroscopy (TDS) measurements were made on D 2 and CD 4 from surface layers of pyrolytic graphite cleavage faces after 3 keV D + 3 irradiation to 1.5 x 10 18 D/cm 2 at irradiation temperatures from 330 to 1000 K. Thermal desorption of both D 2 and CD 4 was observed to rise simultaneously at around 700 K. The D 2 peak was found at T m = 900-1000 K, while the CD 4 peak appeared at a lower temperature, 800-840 K. The T m for the D 2 TDS increased, while that for the CD 4 decreased with increasing irradiation temperature. These results obviously indicate that the D 2 desorption is detrapping/recombination limited, while the CD 4 desorption is most likely to be diffusion limited. The amount of thermally desorbed D 2 after the D + irradiation was observed to monotonously decrease as the irradiation temperature was increased from 330 to 1000 K. These tendencies agreed with previous results for the irradiation temperature dependencies of both C1s chemical shift (XPS) and the interlayer spacing, d 002 (HRTEM), on the graphite basal face. (orig.)

Thermal soil desorption for total petroleum hydrocarbon testing on gas chromatographs

International Nuclear Information System (INIS)

Mott, J.

1995-01-01

Testing for total petroleum hydrocarbons (TPH) is one of the most common analytical tests today. A recent development in chromatography incorporates Thermal Soil Desorption technology to enable analyses of unprepared soil samples for volatiles such as BTEX components and semi-volatiles such as diesel, PCBs, PAHs and pesticides in the same chromatogram, while in the field. A gas chromatograph is the preferred method for determining TPH because the column in a GC separates the individual hydrocarbons compounds such as benzene and toluene from each other and measures each individually. A GC analysis will determine not only the total amount of hydrocarbon, but also whether it is gasoline, diesel or another compound. TPH analysis with a GC is typically conducted with a Flame Ionization Detector (FID). Extensive field and laboratory testing has shown that incorporation of a Thermal Soil Desorber offers many benefits over traditional analytical testing methods such as Headspace, Solvent Extraction, and Purge and Trap. This paper presents the process of implementing Thermal Soil Desorption in gas chromatography, including procedures for, and advantages of faster testing and analysis times, concurrent volatile and semi-volatile analysis, minimized sample manipulation, single gas (H 2 ) operation, and detection to the part-per billion levels

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

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)

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.

XPS study of influence of exposure to air on thermal stability and kinetics of hydrogen decomposition of MgH{sub 2} films obtained by direct hydrogenation from gaseous phase of metallic Mg

Energy Technology Data Exchange (ETDEWEB)

Dobrovolsky, V.D., E-mail: dobersh@ipms.kiev.ua; Khyzhun, O.Y.; Sinelnichenko, A.K.; Ershova, O.G.; Solonin, Y.M.

2017-02-15

Highlights: • Air influence on thermal stability of MgH{sub 2} have been studied by XPS. • XPS spectra of MgH{sub 2} films obtained at different hydrogen pressures have been studied. • Changes in the chemical state of MgH{sub 2} films depending on time of exposure to air are analyzed. • Correlation exists between chemical surface condition of MgH{sub 2} films and their thermal stableness. • Process of hydrogen desorption from MgH{sub 2} films is studied using TDS for model samples. - Abstract: Mechanism of influence of exposure to air on thermal stability of MgH{sub 2} obtained by direct hydrogenation from the gas phase, the nature of the hydride sensitivity to the negative impact of air and the role of its surface chemical state have not been studied enough. The present article presents data of X-ray photoelectron spectroscopy (XPS) measurements of the Mg 2s, O 1s, C 1s core-level spectra of surface of hydride MgH{sub 2} films derived by gas phase hydrogenation of model samples of metallic Mg, and the evolution of changes in the chemical state of the surface of the hydride films depending on the time of exposure to air and formation conditions (hydrogen pressure and hydrogenation regime). Based on results of XPS, X-ray diffraction (XRD), and thermodesorption spectroscopy (TDS), the existence of a relationship (correlation) between chemical surface condition of hydride MgH{sub 2} films obtained at different hydrogen pressures (3.0 MPa and 11.5 MPa) and their thermal stableness and temperature of the beginning of hydride decomposition has been established.

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)

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.

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.

Detection of Nonvolatile Inorganic Oxidizer-Based Explosives from Wipe Collections by Infrared Thermal Desorption-Direct Analysis in Real Time Mass Spectrometry.

Science.gov (United States)

Forbes, Thomas P; Sisco, Edward; Staymates, Matthew

2018-05-07

Infrared thermal desorption (IRTD) was coupled with direct analysis in real time mass spectrometry (DART-MS) for the detection of both inorganic and organic explosives from wipe collected samples. This platform generated discrete and rapid heating rates that allowed volatile and semivolatile organic explosives to thermally desorb at relatively lower temperatures, while still achieving elevated temperatures required to desorb nonvolatile inorganic oxidizer-based explosives. IRTD-DART-MS demonstrated the thermal desorption and detection of refractory potassium chlorate and potassium perchlorate oxidizers, compounds difficult to desorb with traditional moderate-temperature resistance-based thermal desorbers. Nanogram to sub-nanogram sensitivities were established for analysis of a range of organic and inorganic oxidizer-based explosive compounds, with further enhancement limited by the thermal properties of the most common commercial wipe materials. Detailed investigations and high-speed visualization revealed conduction from the heated glass-mica base plate as the dominant process for heating of the wipe and analyte materials, resulting in thermal desorption through boiling, aerosolization, and vaporization of samples. The thermal desorption and ionization characteristics of the IRTD-DART technique resulted in optimal sensitivity for the formation of nitrate adducts with both organic and inorganic species. The IRTD-DART-MS coupling and IRTD in general offer promising explosive detection capabilities to the defense, security, and law enforcement arenas.

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

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)

The direct determination of HgS by thermal desorption coupled with atomic absorption spectrometry

Czech Academy of Sciences Publication Activity Database

Coufalík, Pavel; Zvěřina, O.; Komárek, J.

2016-01-01

Roč. 118, APR (2016), s. 1-5 ISSN 0584-8547 Institutional support: RVO:68081715 Keywords : mercury * HgS * thermal desorption Subject RIV: CB - Analytical Chemistry, Separation Impact factor: 3.241, year: 2016

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

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)

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

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

Thermal desorption and bombardment-induced release of deuterium implanted into stainless steels at low energy

International Nuclear Information System (INIS)

Farrell, G.; Donnelly, S.E.

1978-01-01

Thermal desorption spectra have been obtained for low energy (15-750 eV) deuterons implanted into types 321 and 304 stainless steel, to total fluences in the range 10 13 - 10 17 deuterons/cm 2 . In each case the spectra show a peak at about 350 K, but in the 321 steel there is a second peak in the region of 900 K, the population and peak temperature of which increase with energy. Activation energies of 0.99 and 2.39 eV and a rate constant of 7 x 10 15 /s have been derived for the peaks and it is thought that the first peak corresponds to release from sites close to the surface, while the second peak may be related to trapping at impurities such as Ti. Measurements have also been made of the release of deuterium resulting from post-implantation bombardment with hydrogen ions. It is found that depletion of the first peak in the 321 steel is the result of gas sputtering, but depletion of the second peak is the result of the formation of HD during desorption, while depletion of the peak in the 304 stainless steel also results from HD formation even though this peak is the same as the first peak in the 321 steel. Estimates have also been made of the deuterium self-sputtering cross section at various energies, which show a monotonic decrease as energy increases. (Auth.)

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.

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

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)

Activation of erbium films for hydrogen storage

International Nuclear Information System (INIS)

Brumbach, Michael T.; Ohlhausen, James A.; Zavadil, Kevin R.; Snow, Clark S.; Woicik, Joseph C.

2011-01-01

Hydriding of metals can be routinely performed at high temperature in a rich hydrogen atmosphere. Prior to the hydrogen loading process, a thermal activation procedure is required to promote facile hydrogen sorption into the metal. Despite the wide spread utilization of this activation procedure, little is known about the chemical and electronic changes that occur during activation and how this thermal pretreatment leads to increased rates of hydrogen uptake. This study utilized variable kinetic energy X-ray photoelectron spectroscopy to interrogate the changes during in situ thermal annealing of erbium films, with results confirmed by time-of-flight secondary ion mass spectrometry and low energy ion scattering. Activation can be identified by a large increase in photoemission between the valence band edge and the Fermi level and appears to occur over a two stage process. The first stage involves desorption of contaminants and recrystallization of the oxide, initially impeding hydrogen loading. Further heating overcomes the first stage and leads to degradation of the passive surface oxide leading to a bulk film more accessible for hydrogen loading.

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

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.)

Effects of thermal desorption on the composition of two coking plant soils: Impact on solvent extractable organic compounds and metal bioavailability

Energy Technology Data Exchange (ETDEWEB)

Biache, Coralie [G2R UMR 7566, Nancy Universite, CNRS, Boulevard des Aiguillettes B.P. 239, F-54506 Vandoeuvre-les-Nancy (France); LIMOS UMR 7137, Nancy Universite, CNRS, Boulevard des Aiguillettes B.P. 239, F-54506 Vandoeuvre-les-Nancy (France)], E-mail: coralie.biache@g2r.uhp-nancy.fr; Mansuy-Huault, Laurence; Faure, Pierre [G2R UMR 7566, Nancy Universite, CNRS, Boulevard des Aiguillettes B.P. 239, F-54506 Vandoeuvre-les-Nancy (France); Munier-Lamy, Colette; Leyval, Corinne [LIMOS UMR 7137, Nancy Universite, CNRS, Boulevard des Aiguillettes B.P. 239, F-54506 Vandoeuvre-les-Nancy (France)

2008-12-15

To evaluate the efficiency and the influence of thermal desorption on the soil organic compartment, contaminated soils from coking plant sites (NM and H) were compared to their counterparts treated with thermodesorption. The extractable organic matter, and the metal content and distribution with soil compartments were studied. In both thermodesorbed soils, PAH (polycyclic aromatic hydrocarbon) degradation exceeded 90%. However, the thermal desorption led not only to a volatilization of the organic compounds but also to the condensation of extractable organic matter. The treatments only affected the Fe and Zn distribution within the more stable fractions, whereas the organic compound degradation did not affect their mobility and availability. - Thermal desorption does not induce a metal mobilization but condensation seems to occur during the treatment.

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.

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)

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)

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

High hydrogen desorption properties of Mg-based nanocomposite at moderate temperatures: The effects of multiple catalysts in situ formed by adding nickel sulfides/graphene

Science.gov (United States)

Xie, Xiubo; Chen, Ming; Liu, Peng; Shang, Jiaxiang; Liu, Tong

2017-12-01

Nickel sulfides decorated reduced graphene oxide (rGO) has been produced by co-reducing Ni2+ and graphene oxide (GO), and is subsequently ball milled with Mg nanoparticles (NPs) produced by hydrogen plasma metal reaction (HPMR). The nickel sulfides of about 800 nm completely in situ change to MgS, Mg2Ni and Ni multiple catalysts after first hydrogenation/dehydrogenation process at 673 K. The Mg-5wt%NiS/rGO nanocomposite shows the highest hydrogen desorption kinetics and capacity properties, and the catalytic effect order of the additives is NiS/rGO, NiS and rGO. At 573 K, the Mg-NiS/rGO nanocomposite can quickly desorb 3.7 wt% H2 in 10 min and 4.5 wt% H2 in 60 min. The apparent hydrogen absorption and desorption activation energies of the Mg-5wt%NiS/rGO nanocomposite are decreased to 44.47 and 63.02 kJ mol-1, smaller than those of the Mg-5wt%rGO and Mg-5wt%NiS samples. The best hydrogen desorption properties of the Mg-5wt%NiS/rGO nanocomposite can be explained by the synergistic catalytic effects of the highly dispersed MgS, Mg2Ni and Ni catalysts on the rGO sheets, and the more nucleation sites between the catalysts, rGO sheets and Mg matrix.

Low-temperature thermal reduction of graphene oxide: In situ correlative structural, thermal desorption, and electrical transport measurements

Science.gov (United States)

Lipatov, Alexey; Guinel, Maxime J.-F.; Muratov, Dmitry S.; Vanyushin, Vladislav O.; Wilson, Peter M.; Kolmakov, Andrei; Sinitskii, Alexander

2018-01-01

Elucidation of the structural transformations in graphene oxide (GO) upon reduction remains an active and important area of research. We report the results of in situ heating experiments, during which electrical, mass spectrometry, X-ray photoelectron spectroscopy (XPS), Raman spectroscopy, and transmission electron microscopy (TEM) measurements were carried out correlatively. The simultaneous electrical and temperature programmed desorption measurements allowed us to correlate the onset of the increase in the electrical conductivity of GO by five orders of magnitude at about 150 °C with the maxima of the rates of desorption of H2O, CO, and CO2. Interestingly, this large conductivity change happens at an intermediate level of the reduction of GO, which likely corresponds to the point when the graphitic domains become large enough to enable percolative electronic transport. We demonstrate that the gas desorption is intimately related to (i) the changes in the chemical structure of GO detected by XPS and Raman spectroscopy and (ii) the formation of nanoscopic holes in GO sheets revealed by TEM. These in situ observations provide a better understanding of the mechanism of the GO thermal reduction.

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

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

Behavior of sorption and thermal desorption of fission products from loaded metal oxide exchangers

International Nuclear Information System (INIS)

Buerck, J.

1986-08-01

A new sublimation method for the concentration and purification of 99 Mo, produced by the fission of 235 U with thermal neutrons, has been developed to replace the present final decontamination steps in the various well established 99 Mo separation processes. A distinct simplification and shortening of the actual procedure is obtained by combining the chromatographic sorption on the SnO 2 -exchanger with the direct thermal desorption of the Mo product from the oxide. (orig./PW) [de

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.

Distribution and removal of organochlorine pesticides in waste clay bricks from an abandoned manufacturing plant using low-temperature thermal desorption technology.

Science.gov (United States)

Cong, Xin; Li, Fasheng; Kelly, Ryan M; Xue, Nandong

2018-04-01

The distribution of pollutants in waste clay bricks from an organochlorine pesticide-contaminated site was investigated, and removal of the pollutants using a thermal desorption technology was studied. The results showed that the contents of HCHs in both the surface and the inner layer of the bricks were slightly higher than those of DDTs. The total pore volume of the bricks was 37.7 to 41.6% with an increase from external to internal surfaces. The removal efficiency by thermal treatment was within 62 to 83% for HCHs and DDTs in bricks when the temperature was raised from 200 to 250 °C after 1 h. HCHs were more easily removed than DDTs with a higher temperature. Either intraparticle or surface diffusion controls the desorption processes of pollutants in bricks. It was feasible to use the polluted bricks after removal of the pollutants by low-temperature thermal desorption technology.

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)

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

Demonstration of a batch vacuum thermal desorption process on hazardous and mixed waste

International Nuclear Information System (INIS)

Palmer, C.R.; McElwee, M.; Meyers, G.

1995-01-01

Many different waste streams have been identified at Department of Energy (DOE) facilities as having both hazardous organic and radioactive contaminants. There is presently only one permitted facility in which to manage these materials, and that facility has only limited capacity to process solid wastes. Over the past two years, Rust has been pilot testing a new thermal desorption process that is very well suited to these wastes, and has begun permitting and design of a unit for commercial operation. This paper presents both historic and recent pilot test data on the treatment of hazardous and mixed waste. Also described is the commercial unit. Rust's patented VAC*TRAX technology takes advantage of high vacuum to reduced operating temperature for the thermal desorption of organic contaminants from waste soils, sludges and other contaminated solids. This allows for economical thermal separation on relatively small sites (30 to 5,000 m 3 of waste). VAC*TRAX employs indirect heating; this, combined with a very low carrier gas flow, results in a vent flow rate of approximately 1 m 3 /min which allows for the use of control devices that would not be practical with conventional thermal technology. The unit is therefore ideally suited to processing mixed waste, since zero radioactive emissions can be maintained. An additional benefit of the technology is that the low operating temperature allows highly effective separation to be performed well below the degradation point for the solid components of a trash type waste stream, which constitutes a large fraction of the present mixed waste inventory

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.

Photon-induced Processing of Interstellar Ices in the Laboratory. Focus on Their Non-thermal Desorption.

Science.gov (United States)

Martin-Domenech, Rafael; Munoz Caro, Guillermo; Cruz-Diaz, Gustavo A.; Oberg, Karin I.

2018-06-01

Some of the processes that take place in the interstellar medium (ISM)can be simulated in laboratories on Earth under astrophysically relevant conditions. For example, the energetic processing of the ice mantles that accrete on top of dust grains in the coldest regions of the ISM, leading to the production of new species and their desorption to the gas phase. In particular, observation of complex organic molecules (COMs) in cold interstellar environments stress the need for not only a solid state formation but also for non-thermal desorption mechanisms that can account for the observed abundances in regions where thermal desorption is inhibited. Laboratory Astrophysics can be used to test different non-thermal desorption processes and extract yields than can be extrapolated to the astrophysical scenario with theoretical models. 0th generation COMs like CH3OH and H2CO can be formed at very low temperatures. In this talk, we present laboratory simulations of the UV photoprocessing of a binary ice mixture composed by water (the main component of astrophysical ices) and methane. Formation of CO, CO2, CH3OH and H2CO was confirmed by IR spectroscopy and subsequent TPD. At the same time, photodesorption of CO and H2CO was detected by means of a Quadrupole Mass Spectrometer, with yields on the order of 10-4 and 10-5 molecules per incident photon, respectively. In general, photodesorption can take place through a direct mechanism, where the absorbing molecule (or its photofragments) are desorbed; or through an indirect mechanism where the absorbed energy is transferred to a surface molecule which is the one finally desorbing. In the case of photoproducts, the evolution of the photodesorption yield gives information on the photodesorption mechanism: a constant photodesorption yield is observed when the photoproducts are desorbed right after their formation; while an increasing yield is measured when the photoproducts are desorbed later after energy transfer from another

Thermal desorption of formamide and methylamine from graphite and amorphous water ice surfaces

Science.gov (United States)

Chaabouni, H.; Diana, S.; Nguyen, T.; Dulieu, F.

2018-04-01

Context. Formamide (NH2CHO) and methylamine (CH3NH2) are known to be the most abundant amine-containing molecules in many astrophysical environments. The presence of these molecules in the gas phase may result from thermal desorption of interstellar ices. Aims: The aim of this work is to determine the values of the desorption energies of formamide and methylamine from analogues of interstellar dust grain surfaces and to understand their interaction with water ice. Methods: Temperature programmed desorption (TPD) experiments of formamide and methylamine ices were performed in the sub-monolayer and monolayer regimes on graphite (HOPG) and non-porous amorphous solid water (np-ASW) ice surfaces at temperatures 40-240 K. The desorption energy distributions of these two molecules were calculated from TPD measurements using a set of independent Polanyi-Wigner equations. Results: The maximum of the desorption of formamide from both graphite and ASW ice surfaces occurs at 176 K after the desorption of H2O molecules, whereas the desorption profile of methylamine depends strongly on the substrate. Solid methylamine starts to desorb below 100 K from the graphite surface. Its desorption from the water ice surface occurs after 120 K and stops during the water ice sublimation around 150 K. It continues to desorb from the graphite surface at temperatures higher than160 K. Conclusions: More than 95% of solid NH2CHO diffuses through the np-ASW ice surface towards the graphitic substrate and is released into the gas phase with a desorption energy distribution Edes = 7460-9380 K, which is measured with the best-fit pre-exponential factor A = 1018 s-1. However, the desorption energy distribution of methylamine from the np-ASW ice surface (Edes = 3850-8420 K) is measured with the best-fit pre-exponential factor A = 1012 s-1. A fraction of solid methylamine monolayer of roughly 0.15 diffuses through the water ice surface towards the HOPG substrate. This small amount of methylamine

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

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

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}.

Re-emission and thermal desorption of deuterium from plasma sprayed tungsten coatings for application in ASDEX-upgrade

International Nuclear Information System (INIS)

Garcia-Rosales, C.; Franzen, P.; Plank, H.; Roth, J.; Gauthier, E.

1996-01-01

The trapping and release of deuterium implanted with an energy of 100 eV in wrought and in plasma sprayed tungsten of different manufacture and structure has been investigated by means of re-emission as well as thermal and isothermal desorption spectroscopy. The experimental data for wrought tungsten are compared with model calculations with the PIDAT code in order to estimate the parameters governing diffusion, surface recombination and trapping in tungsten. The amount of retained deuterium in tungsten is of the same order of magnitude as in graphite for the implantation parameters used in this work. The mobile hydrogen concentration in tungsten during the implantation is of the same order of magnitude than the trapped one, being released after the termination of the implantation. The fraction of deuterium trapped to defects increases strongly with the porosity of the samples. The temperature needed for the release of the trapped deuterium (∝600 K) are considerably lower than for graphite, due to the smaller trapping energy (≤1.5 eV). (orig.)

Thermal diffusion of hydrogen in zircaloy-2 containing hydrogen beyond terminal solid solubility

International Nuclear Information System (INIS)

Maki, Hideo; Sato, Masao.

1975-01-01

The thermal diffusion of hydrogen is one of causes of uneven hydride precipitation in zircaloy fuel cladding tubes that are used in water reactors. In the diffusion model of hydrogen in zircaloy, the effects of the hydride on the diffusibility of hydrogen has been regarded as negligibly small in comparison with that of hydrogen dissolved in the matrix. Contrary to the indications given by this model, phenomena are often encountered that cannot be explained unless hydride platelets have considerable ostensible diffusibility in zircaloy. In order to determine quantitatively the diffusion characteristics of hydrogen in zircaloy, a thermal diffusion experiment was performed with zircaloy-2 fuel cladding tubes containing hydrogen beyond the terminal solid solubility. In this experiment, a temperature difference of 20 0 --30 0 C was applied between the inside and outside surfaces of the specimen in a thermal simulator. To explain the experimental results, a modified diffusion model is presented, in which the effects of stress are introduced into Markowitz's model with the diffusion of hydrogen in the hydride taken into account. The diffusion equation derived from this model can be written in a form that ostensibly represents direct diffusion of hydride in zircaloy. The apparent diffusion characteristics of the hydride at around 300 0 C are Dsub(p)=2.3x10 5 exp(-32,000/RT), (where R:gas constant, T:temperature) and the apparent heat of transport Qsub(p) =-60,000 cal/mol. The modified diffusion model well explains the experimental results in such respects as reaches a steady state after several hours. (auth.)

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.

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.

Determination of the carbon isotopic composition of whole/intact biological specimens using at-line direct thermal desorption to effect thermally assisted hydrolysis/methylation

NARCIS (Netherlands)

Akoto, L.; Vreuls, R.J.J.; Irth, H.; Floris, V.; Hoogveld, H.L.; Pel, R.

2008-01-01

In this paper, we discuss the use of a direct thermal desorption (DTD) interface as an alternative to Curie-point flash pyrolysis system as an inlet technique in gas chromatography–combustion isotope-ratio mass spectrometry (GC/C-IRMS) analysis of whole/intact phytoplankton and zooplankton

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.

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.

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 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.

"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.

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.

At-line gas chromatographic-mass spectrometric analysis of fatty acid profiles of green microalgae using a direct thermal desorption interface

NARCIS (Netherlands)

Blokker, P.; Pel, R.; Akoto, L.; Udo, A.; Brinkman, U.A.Th.; Vreuls, R.J.J.

2002-01-01

Thermally assisted hydrolysis and methylation¯gas chromatography (THM¯GC) is an important tool to analyse fatty acid in complex matrices. Since THM¯GC has major drawbacks such as isomerisation when applied to fatty acids in natural matrices, a direct thermal desorption (DTD) interface and an

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.

Rate equations modeling for hydrogen inventory studies during a real tokamak material thermal cycle

Energy Technology Data Exchange (ETDEWEB)

Bonnin, X., E-mail: xavier.bonnin@iter.org [LSPM-CNRS, Université Paris 13, Sorbonne Paris Cité, 99 avenue Jean-Baptiste Clément, F-93430 Villetaneuse (France); Hodille, E. [IRFM, CEA-Cadarache, F-13108 St-Paul-Lez-Durance (France); Ning, N. [LSPM-CNRS, Université Paris 13, Sorbonne Paris Cité, 99 avenue Jean-Baptiste Clément, F-93430 Villetaneuse (France); Sang, C. [School of Physics and Optoelectronics Technology, Dalian University of Technology, Dalian 116024 (China); Grisolia, Ch. [IRFM, CEA-Cadarache, F-13108 St-Paul-Lez-Durance (France)

2015-08-15

Prediction and control of tritium inventory in plasma-facing components (PFCs) is a critical nuclear safety issue for ITER and future fusion devices. This goal can be achieved through rate equations models as presented here. We calibrate our models with thermal desorption spectrometry results to obtain a validated set of material parameters relevant to hydrogen inventory processes in bulk tungsten. The best fits are obtained with two intrinsic trap types, deep and shallow, and an extrinsic trap created by plasma irradiation and plastic deformation of the tungsten matrix associated with blister formation. We then consider a realistic cycle of plasma discharges consisting of 400 s of plasma exposure followed by a resting period of 1000 s, repeating for several hours. This cycle is then closed by a long “overnight” period, thus providing an estimate of the amount of tritium retained in the PFCs after a full day of standard operation.

Hydrogenation of Penta-Graphene Leads to Unexpected Large Improvement in Thermal Conductivity.

Science.gov (United States)

Wu, Xufei; Varshney, Vikas; Lee, Jonghoon; Zhang, Teng; Wohlwend, Jennifer L; Roy, Ajit K; Luo, Tengfei

2016-06-08

Penta-graphene (PG) has been identified as a novel two-dimensional (2D) material with an intrinsic bandgap, which makes it especially promising for electronics applications. In this work, we use first-principles lattice dynamics and iterative solution of the phonon Boltzmann transport equation (BTE) to determine the thermal conductivity of PG and its more stable derivative, hydrogenated penta-graphene (HPG). As a comparison, we also studied the effect of hydrogenation on graphene thermal conductivity. In contrast to hydrogenation of graphene, which leads to a dramatic decrease in thermal conductivity, HPG shows a notable increase in thermal conductivity, which is much higher than that of PG. Considering the necessity of using the same thickness when comparing thermal conductivity values of different 2D materials, hydrogenation leads to a 63% reduction in thermal conductivity for graphene, while it results in a 76% increase for PG. The high thermal conductivity of HPG makes it more thermally conductive than most other semiconducting 2D materials, such as the transition metal chalcogenides. Our detailed analyses show that the primary reason for the counterintuitive hydrogenation-induced thermal conductivity enhancement is the weaker bond anharmonicity in HPG than PG. This leads to weaker phonon scattering after hydrogenation, despite the increase in the phonon scattering phase space. The high thermal conductivity of HPG may inspire intensive research around HPG and other derivatives of PG as potential materials for future nanoelectronic devices. The fundamental physics understood from this study may open up a new strategy to engineer thermal transport properties of other 2D materials by controlling bond anharmonicity via functionalization.

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.

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.

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.)

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

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.

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.

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.)

Analysis of airborne pesticides from different chemical classes adsorbed on Radiello® Tenax® passive tubes by thermal-desorption-GC/MS.

Science.gov (United States)

Raeppel, Caroline; Fabritius, Marie; Nief, Marie; Appenzeller, Brice M R; Briand, Olivier; Tuduri, Ludovic; Millet, Maurice

2015-02-01

An analytical methodology using automatic thermal desorption (ATD) and GC/MS was developed for the determination of 28 pesticides of different chemical classes (dichlobenil, carbofuran, trifluralin, clopyralid, carbaryl, flazasulfuron, mecoprop-P, dicamba, 2,4-MCPA, dichlorprop, 2,4-D, triclopyr, cyprodinil, bromoxynil, fluroxypyr, oxadiazon, myclobutanil, buprofezin, picloram, trinexapac-p-ethyl, ioxynil, diflufenican, tebuconazole, bifenthrin, isoxaben, alphacypermethrin, fenoxaprop and tau-fluvalinate) commonly used in nonagricultural areas in atmospheric samples. This methodology was developed to evaluate the indoor and outdoor atmospheric contamination by nonagricultural pesticides. Pesticides were sampled passive sampling tubes containing Tenax® adsorbent. Since most of these pesticides are polar (clopyralid, mecoprop-P, dicamba, 2,4-MCPA, dichlorprop, 2,4-D, triclopyr, bromoxynil, fluroxypyr, picloram, trinexapac-p-ethyl and ioxynil), a derivatisation step is required. For this purpose, a silylation step using N-(t-butyldimethylsilyl)-N-methyltrifluoroacetamide (MtBSTFA) was added before thermal desorption. This agent was chosen since it delivers very specific ions on electronic impact (m/z = M-57). This method was established with special consideration for optimal thermal desorption conditions (desorption temperature, desorb flow and duration; trap heating duration and flow; outlet split), linear ranges, limits of quantification and detection which varied from 0.005 to 10 ng and from 0.001 to 2.5 ng, respectively, for an uncertainty varied from 8 to 30 %. The method was applied in situ to the analysis of passive tubes exposed during herbicide application to an industrial site in east of France.

Direct analysis of anabolic steroids in urine using Leidenfrost phenomenon assisted thermal desorption-dielectric barrier discharge ionization mass spectrometry.

Science.gov (United States)

Saha, Subhrakanti; Mandal, Mridul Kanti; Nonami, Hiroshi; Hiraoka, Kenzo

2014-08-11

Rapid detection of trace level anabolic steroids in urine is highly desirable to monitor the consumption of performance enhancing anabolic steroids by athletes. The present article describes a novel strategy for identifying the trace anabolic steroids in urine using Leidenfrost phenomenon assisted thermal desorption (LPTD) coupled to dielectric barrier discharge (DBD) ionization mass spectrometry. Using this method the steroid molecules are enriched within a liquid droplet during the thermal desorption process and desorbed all-together at the last moment of droplet evaporation in a short time domain. The desorbed molecules were ionized using a dielectric barrier discharge ion-source in front of the mass spectrometer inlet at open atmosphere. This process facilitates the sensitivity enhancement with several orders of magnitude compared to the thermal desorption at a lower temperature. The limits of detection (LODs) of various steroid molecules were found to be in the range of 0.05-0.1 ng mL(-1) for standard solutions and around two orders of magnitude higher for synthetic urine samples. The detection limits of urinary anabolic steroids could be lowered by using a simple and rapid dichloromethane extraction technique. The analytical figures of merit of this technique were evaluated at open atmosphere using suitable internal standards. The technique is simple and rapid for high sensitivity and high throughput screening of anabolic steroids in urine. Copyright © 2014 Elsevier B.V. All rights reserved.

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)

Availability of steam generator against thermal disturbance of hydrogen production system coupled to HTGR

International Nuclear Information System (INIS)

Shibata, Taiju; Nishihara, Tetsuo; Hada, Kazuhiko; Shiozawa, Shusaku

1996-01-01

One of the safety issues to couple a hydrogen production system to an HTGR is how the reactor coolability can be maintained against anticipated abnormal reduction of heat removal (thermal disturbance) of the hydrogen production system. Since such a thermal disturbance is thought to frequently occur, it is desired against the thermal disturbance to keep reactor coolability by means other than reactor scram. Also, it is thought that the development of a passive cooling system for such a thermal disturbance will be necessary from a public acceptance point of view in a future HTGR-hydrogen production system. We propose a SG as the passive cooling system which can keep the reactor coolability during a thermal disturbance of a hydrogen production system. This paper describes the proposed steam generator (SG) for the HTGR-hydrogen production system and a result of transient thermal-hydraulic analysis of the total system, showing availability of the SG against a thermal disturbance of the hydrogen production system in case of the HTTR-steam reforming hydrogen production system. (author)

Atmospheric Pressure-Thermal Desorption (AP-TD)/Electrospray Ionization-Mass Spectrometry for the Rapid Analysis of Bacillus Spores

Science.gov (United States)

A technique is described where an atmospheric pressure-thermal desorption (AP-TD) device and electrospray ionization (ESI)-mass spectrometry are coupled and used for the rapid analysis of Bacillus spores in complex matrices. The resulting AP-TD/ESI-MS technique combines the generation of volatile co...

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.)

Carbon compound used in hydrogen storage; Compuesto de carbon utilizado en almacenamiento de hidrogeno

Energy Technology Data Exchange (ETDEWEB)

Iturbe G, J L; Lopez M, B E [ININ, 52045 Ocoyoacac, Estado de Mexico (Mexico)

2004-07-01

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)

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.

Hydrogen Fueling Station Using Thermal Compression: a techno-economic analysis

Energy Technology Data Exchange (ETDEWEB)

Kriha, Kenneth [Gas Technology Inst., Des Plaines, IL (United States); Petitpas, Guillaume [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Melchionda, Michael [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Soto, Herie [Shell, Houston TX (United States); Feng, Zhili [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Wang, Yanli [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)

2017-08-11

The goal of this project was to demonstrate the technical and economic feasibility of using thermal compression to create the hydrogen pressure necessary to operate vehicle hydrogen fueling stations. The concept of utilizing the exergy within liquid hydrogen to build pressure rather than mechanical components such as compressors or cryogenic liquid pumps has several advantages. In theory, the compressor-less hydrogen station will have lower operating and maintenance costs because the compressors found in conventional stations require large amounts of electricity to run and are prone to mechanical breakdowns. The thermal compression station also utilizes some of the energy used to liquefy the hydrogen as work to build pressure, this is energy that in conventional stations is lost as heat to the environment.

Measurement of volatile plant compounds in field ambient air by thermal desorption-gas chromatography-mass spectrometry.

Science.gov (United States)

Cai, Xiao-Ming; Xu, Xiu-Xiu; Bian, Lei; Luo, Zong-Xiu; Chen, Zong-Mao

2015-12-01

Determination of volatile plant compounds in field ambient air is important to understand chemical communication between plants and insects and will aid the development of semiochemicals from plants for pest control. In this study, a thermal desorption-gas chromatography-mass spectrometry (TD-GC-MS) method was developed to measure ultra-trace levels of volatile plant compounds in field ambient air. The desorption parameters of TD, including sorbent tube material, tube desorption temperature, desorption time, and cold trap temperature, were selected and optimized. In GC-MS analysis, the selected ion monitoring mode was used for enhanced sensitivity and selectivity. This method was sufficiently sensitive to detect part-per-trillion levels of volatile plant compounds in field ambient air. Laboratory and field evaluation revealed that the method presented high precision and accuracy. Field studies indicated that the background odor of tea plantations contained some common volatile plant compounds, such as (Z)-3-hexenol, methyl salicylate, and (E)-ocimene, at concentrations ranging from 1 to 3400 ng m(-3). In addition, the background odor in summer was more abundant in quality and quantity than in autumn. Relative to previous methods, the TD-GC-MS method is more sensitive, permitting accurate qualitative and quantitative measurements of volatile plant compounds in field ambient air.

Effects of H2O and H2O2 on thermal desorption of tritium from stainless steel

International Nuclear Information System (INIS)

Quinlan, M. J.; Shmayda, W. T.; Lim, S.; Salnikov, S.; Chambers, Z.; Pollock, E.; Schroeder, W. U.

2008-01-01

Tritiated stainless steel was subjected to thermal desorption at various temperatures, different temperature profiles, and in the presence of different helium carrier gas additives. In all cases the identities of the desorbing tritiated species were characterized as either water-soluble or insoluble. The samples were found to contain 1.1 mCi±0.4 mCi. Approximately ninety-five percent of this activity was released in molecular water-soluble form. Additives of H 2 O or H 2 O 2 to dry helium carrier gas increase the desorption rate and lower the maximum temperature to which the sample must be heated, in order to remove the bulk of the tritium. The measurements validate a method of decontamination of tritiated steel and suggest a technique that can be used to further explore the mechanisms of desorption from tritiated metals. (authors)

Study of heterogeneous catalytic processes over cobalt, molybdenum and cobalt-molybdenum catalysts supported on alumina by temperature-programmed desorption and temperature-programmed reaction. 1. Adsorption of hydrozen

International Nuclear Information System (INIS)

Rozanov, V.V.; Tsao Yamin; Krylov, O.V.

1996-01-01

Hydrogen adsorption on reduced, sulphidized and reoxidized specimens of molybdenum-and cobalt-molybdenum-containing catalysts applied on aluminium oxide has been studied by the method of thermal desorption (TD). Comparison of TD spectra of hydrogen and data of X-ray phase analysis of the specimens and mass-spectrometric analysis of the products desorbed from the surface of catalysts after their successive reduction sulphidizing, carbonizing and reoxidation permitted a correlation between various forms of hydrogen adsorption and certain centres on the surface of the catalysts. 12 refs., 2 figs

Trapping hydropyrolysates on silica and their subsequent desorption to facilitate rapid fingerprinting by GC-MS

Energy Technology Data Exchange (ETDEWEB)

Meredith, W.; Russell, C.A.; Cooper, M.; Snape, C.E. [Nottingham Univ. (United Kingdom). Fuel and Energy Centre; Love, G.D. [Newcastle upon Tyne Univ. (United Kingdom). School of Civil Engineering and Geosciences; Fabbri, D. [Universita di Bologna, Ravenna (Italy). Lab. di Chimica Ambientale; Vane, C.H. [British Geological Society, Keyworth (United Kingdom)

2004-01-01

Analytical hydropyrolysis performed under high hydrogen gas pressure (>10 MPa) has been demonstrated to possess the unique ability to release high yields of biomarker hydrocarbons covalently bound within the non-hydrocarbon macromolecular fraction of crude oils and source rocks. This study describes the development of the experimental procedure for trapping the product oils (hydropyrolysates) on silica to facilitate more convenient recovery than conventional collection and to allow analysis by thermal desorption-GC-MS without any prior work-up. Conventionally, the trap has consisted of a stainless steel coil, cooled with dry ice from which the products are recovered in organic solvents. Replacing this with a system in which the hydropyrolysates are adsorbed on a small mass of silica greatly reduces the turn-around time between tests, and aids the recovery and separation of the products. This method has been developed using an oil shale and an oil asphaltene fraction, with the silica trap producing very similar biomarker profiles to that from the conventional trap. The quantitative recovery of hydrocarbons from a light crude oil desorbed from silica under hydropyrolysis conditions demonstrates no significant loss of the high molecular weight n-alkanes (>n-C{sub 10}) for both trapping methods. The use of liquid nitrogen as the trap coolant results in significantly improved recovery of the lower molecular mass constituents. The silica trapping method allows for the hydropyrolysates to be characterised by thermal desorption-GC-MS, which has been investigated both on- and off-line. The oils undergo relatively little cracking during desorption, with similar n-alkane and biomarker profiles being obtained as with normal work-up and GC-MS analysis. Thus, in terms of fingerprinting geomacromolecules, ''hypy-thermal desorption-GC-MS'' appears to have the potential to be developed as an attractive alternative to traditional py-GC-MS. (author)

Thermal reorientation of hydrogenic Pr3+ centers

International Nuclear Information System (INIS)

Jones, G. D.

1996-01-01

Sets of five multi-hydrogenic centers of both CaF 2 :Pr 3+ and SrF 2 :Pr 3 + show bleaching under selective polarized-light irradiation. Two forms of bleaching behaviour are observed. In reversible polarized bleaching, irradiation creates re-oriented equivalent centers, which can be restored to the original orientation by switching the laser polarization by 90 deg. Indefinite sequences of bleaching and recovery can be established. In photoproduct bleaching, inequivalent centers are produced, which can be reverted by subsequently selectively exciting their absorption lines. Thermal recovery of the bleached centers on warming the crystals occurs abruptly over a 5 K range around 100 K and is noteworthy in occurring at essentially identical temperatures for H - , D - and T - centers. The simplest model for this thermal recovery is thermal activation of the mobile hydrogenic ions over a double well potential barrier. An alternative model proposed by Universitaet Regensburg requires the involvement of high frequency excitations in scattering processes for surmounting the barrier

SUPERFUND TREATABILITY CLEARINGHOUSE: TECHNOLOGY DEMONSTRATION OF A THERMAL DESORPTION/UV PHOTOLYSIS PROCESS FOR DECONTAMINATING SOILS CONTAINING HERBICIDE ORANGE

Science.gov (United States)

This treatability study report presents the results of laboratory and field tests on the effectiveness of a new decontamination process for soils containing 2,4-D/2,4,5-T and traces of dioxin. The process employs three operations, thermal desorption, condensation and absorp...

Mercury speciation during in situ thermal desorption in soil

Energy Technology Data Exchange (ETDEWEB)

Park, Chang Min, E-mail: cmpark80@gmail.com; Katz, Lynn E.; Liljestrand, Howard M.

2015-12-30

Highlights: • Impact of soil conditions on distribution and phase transitions of Hg was identified. • Metallic Hg was slowly transformed to Hg{sup 0} gas until the temperature reached 358.15 K. • Phase change of HgCl{sub 2(s)} completely occurred without decomposition at 335.15 K. • HgS remained solid in dry soil sharply decreased in the narrow temperature range. • Hg gas can be easily captured with higher vapor pressures of soil compositions. - Abstract: Metallic mercury (Hg{sup 0}) and its compounds are highly mobile and toxic environmental pollutants at trace level. In situ thermal desorption (ISTD) is one of the soil remediation processes applying heat and vacuum simultaneously. Knowledge of thermodynamic mercury speciation is imperative to understand the fate and transport of mercury during thermal remediation and operate the treatment processes in a cost-effective manner. Hence, speciation model for inorganic mercury was developed over a range of environmental conditions to identify distribution of dissolved mercury species and potential transformations of mercury at near source environment. Simulation of phase transitions for metallic mercury, mercury(II) chloride and mercury sulfide with temperature increase showed that complete vaporization of metallic mercury and mercury(II) chloride were achieved below the boiling point of water. The effect of soil compositions on mercury removal was also evaluated to better understand thermal remediation process. Higher vapor pressures expected both from soil pore water and inorganic carbonate minerals in soil as well as creation of permeability were significant for complete vaporization and removal of mercury.

Mercury speciation during in situ thermal desorption in soil

International Nuclear Information System (INIS)

Park, Chang Min; Katz, Lynn E.; Liljestrand, Howard M.

2015-01-01

Highlights: • Impact of soil conditions on distribution and phase transitions of Hg was identified. • Metallic Hg was slowly transformed to Hg"0 gas until the temperature reached 358.15 K. • Phase change of HgCl_2_(_s_) completely occurred without decomposition at 335.15 K. • HgS remained solid in dry soil sharply decreased in the narrow temperature range. • Hg gas can be easily captured with higher vapor pressures of soil compositions. - Abstract: Metallic mercury (Hg"0) and its compounds are highly mobile and toxic environmental pollutants at trace level. In situ thermal desorption (ISTD) is one of the soil remediation processes applying heat and vacuum simultaneously. Knowledge of thermodynamic mercury speciation is imperative to understand the fate and transport of mercury during thermal remediation and operate the treatment processes in a cost-effective manner. Hence, speciation model for inorganic mercury was developed over a range of environmental conditions to identify distribution of dissolved mercury species and potential transformations of mercury at near source environment. Simulation of phase transitions for metallic mercury, mercury(II) chloride and mercury sulfide with temperature increase showed that complete vaporization of metallic mercury and mercury(II) chloride were achieved below the boiling point of water. The effect of soil compositions on mercury removal was also evaluated to better understand thermal remediation process. Higher vapor pressures expected both from soil pore water and inorganic carbonate minerals in soil as well as creation of permeability were significant for complete vaporization and removal of mercury.

Thermal desorption of deuterium implanted into beryllium

International Nuclear Information System (INIS)

Markin, A.V.; Chernikov, V.N.; Zakharov, A.P.

1995-01-01

By means of TDS measurements it is shown that the desorption of deuterium from Be implanted with 5 keV D ions to fluences, Φ, from 1x10 20 D/m 2 to 1x10 21 D/m 2 proceeds in one high temperature stage B, while at Φ ≥ 1.2x10 21 D/m 2 one more stage A is added. The desorption maximum A is narrow and consists of two peaks A 1 and A 2 at about 460 K and 490 K, respectively. Peak A 1 is attributed to the desorption of deuterium from the walls of opened channels formed under D ion implantation. Peak A 2 is a consequence of the opening of a part of closed bubbles/channels to the outer surface. The position of maximum B shifts noticeably and nonsteadily on the fluence in a range from 850 to 1050 K. The origin of this maximum is the liberation of D atoms bound at vacancy complexes discussed previously by Wampler. The dependence of Tm(B) on the fluence is governed by the interaction of freely migrating D atoms with partly opened or fully closed gas cavity arrangements which are created under temperature ramping, but differently in specimens implanted with D ions to different fluences

Hydrogen enhanced thermal fatigue of y-titanium aluminide

NARCIS (Netherlands)

Dunfee, William; Gao, Ming; Wei, Robert P.; Wei, W.

1995-01-01

A study of hydrogen enhanced thermal fatigue cracking was carried out for a gamma-based Ti-48Al-2Cr alloy by cycling between room temperature and 750 or 900 °C. The results showed that hydrogen can severely attack the gamma alloy, with resulting lifetimes as low as three cycles, while no failures

Trace level detection of explosives in solution using leidenfrost phenomenon assisted thermal desorption ambient mass spectrometry.

Science.gov (United States)

Saha, Subhrakanti; Mandal, Mridul Kanti; Chen, Lee Chuin; Ninomiya, Satoshi; Shida, Yasuo; Hiraoka, Kenzo

2013-01-01

The present paper demonstrates the detection of explosives in solution using thermal desorption technique at a temperature higher than Leidenfrost temperature of the solvent in combination with low temperature plasma (LTP) ionization. Leidenfrost temperature of a solvent is the temperature above which the solvent droplet starts levitation instead of splashing when placed on a hot metallic surface. During this desorption process, slow and gentle solvent evaporation takes place, which leads to the pre-concentration of less-volatile explosive molecules in the droplet and the explosive molecules are released at the last moment of droplet evaporation. The limits of detection for explosives studied by using this thermal desorption LTP ionization method varied in a range of 1 to 10 parts per billion (ppb) using a droplet volume of 20 μL (absolute sample amount 90-630 fmol). As LTP ionization method was applied and ion-molecule reactions took place in ambient atmosphere, various ion-molecule adduct species like [M+NO2](-), [M+NO3](-), [M+HCO3](-), [M+HCO4](-) were generated together with [M-H](-) peak. Each peak was unambiguously identified using 'Exactive Orbitrap' mass spectrometer in negative ionization mode within 3 ppm deviation compared to its exact mass. This newly developed technique was successfully applied to detect four explosives contained in the pond water and soil sample with minor sample pre-treatment and the explosives were detected with ppb levels. The present method is simple, rapid and can detect trace levels of explosives with high specificity from solutions.

DEMONSTRATION BULLETIN: THE ECO LOGIC THERMAL DESORPTION UNIT - MIDDLEGROUND LANDFILL - BAY CITY, MI - ELI ECO LOGIC INTERNATIONAL, INC.

Science.gov (United States)

ECO Logic has developed a thermal desorption unit 0"DU) for the treatment of soils contaminated with hazardous organic contaminants. This TDU has been designed to be used in conjunction with Eco Logic's patented gas-phase chemical reduction reactor. The Eco Logic reactor is the s...

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.

In-situ TEM on (de)hydrogenation of Pd at 0.5-4.5 bar hydrogen pressure and 20-400°C.

Science.gov (United States)

Yokosawa, Tadahiro; Alan, Tuncay; Pandraud, Gregory; Dam, Bernard; Zandbergen, Henny

2012-01-01

We have developed a nanoreactor, sample holder and gas system for in-situ transmission electron microscopy (TEM) of hydrogen storage materials up to at least 4.5 bar. The MEMS-based nanoreactor has a microheater, two electron-transparent windows and a gas inlet and outlet. The holder contains various O-rings to have leak-tight connections with the nanoreactor. The system was tested with the (de)hydrogenation of Pd at pressures up to 4.5 bar. The Pd film consisted of islands being 15 nm thick and 50-500 nm wide. In electron diffraction mode we observed reproducibly a crystal lattice expansion and shrinkage owing to hydrogenation and dehydrogenation, respectively. In selected-area electron diffraction and bright/dark-field modes the (de)hydrogenation of individual Pd particles was followed. Some Pd islands are consistently hydrogenated faster than others. When thermally cycled, thermal hysteresis of about 10-16°C between hydrogen absorption and desorption was observed for hydrogen pressures of 0.5-4.5 bar. Experiments at 0.8 bar and 3.2 bar showed that the (de)hydrogenation temperature is not affected by the electron beam. This result shows that this is a fast method to investigate hydrogen storage materials with information at the nanometer scale. Copyright © 2011 Elsevier B.V. All rights reserved.

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

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.

VAC*TRAX - Thermal desorption for mixed wastes

International Nuclear Information System (INIS)

McElwee, M.J.; Palmer, C.R.

1995-01-01

The patented VAC*TRAX process was designed in response to the need to remove organic constituents from mixed waste, waste that contains both a hazardous (RCRA or TSCA regulated) component and a radioactive component. Separation of the mixed waste into its hazardous and radioactive components allows for ultimate disposal of the material at existing, permitted facilities. The VAC*TRAX technology consists of a jacketed vacuum dryer followed by a condensing train. Solids are placed in the dryer and indirectly heated to temperatures as high as 260 degrees C, while a strong vacuum (down to 50 mm Hg absolute pressure) is applied to the system and the dryer is purged with a nitrogen carrier gas. The organic contaminants in the solids are thermally desorbed, swept up in the carrier gas and into the condensing train where they are cooled and recovered. The dryer is fitted with a filtration system that keeps the radioactive constituents from migrating to the condensate. As such, the waste is separated into hazardous liquid and radioactive solid components, allowing for disposal of these streams at a permitted incinerator or a radioactive materials landfill, respectively. The VAC*TRAX system is designed to be highly mobile, while minimizing the operational costs with a simple, robust process. These factors allow for treatment of small waste streams at a reasonable cost. This paper describes the VAC*TRAX thermal desorption process, as well as results from the pilot testing program. Also, the design and application of the full-scale treatment system is presented. Materials tested to date include spiked soil and debris, power plant trash and sludge contaminated with solvents, PCB contaminated soil, solvent-contaminated uranium mill-tailings, and solvent and PCB-contaminated sludge and trash. Over 70 test runs have been performed using the pilot VAC*TRAX system, with more than 80% of the tests using mixed waste as the feed material

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.

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.

Thermal decomposition of silane to form hydrogenated amorphous Si

Science.gov (United States)

Strongin, M.; Ghosh, A.K.; Wiesmann, H.J.; Rock, E.B.; Lutz, H.A. III

Hydrogenated amorphous silicon is produced by thermally decomposing silane (SiH/sub 4/) or other gases comprising H and Si, at elevated temperatures of about 1700 to 2300/sup 0/C, in a vacuum of about 10/sup -8/ to 10/sup -4/ torr. A gaseous mixture is formed of atomic hydrogen and atomic silicon. The gaseous mixture is deposited onto a substrate to form hydrogenated amorphous silicon.

Study of Perylenetetracarboxylic Acid Dimethylimide Films by Cyclic Thermal Desorption and Scanning Probe Microscopy

Science.gov (United States)

Pochtennyi, A. E.; Lappo, A. N.; Il'yushonok, I. P.

2018-02-01

Some results of studying the direct-current (DC) conductivity of perylenetetracarboxylic acid dimethylimide films by cyclic oxygen thermal desorption are presented. The microscopic parameters of hopping electron transport over localized impurity and intrinsic states were determined. The bandgap width and the sign of major current carriers were determined by scanning probe microscopy methods (atomic force microscopy, scanning probe spectroscopy, and photoassisted Kelvin probe force microscopy). The possibility of the application of photoassisted scanning tunneling microscopy for the nanoscale phase analysis of photoconductive films is discussed.

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.)

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.

Hydrogen retention behavior of beryllides as advanced neutron multipliers

Directory of Open Access Journals (Sweden)

Y. Fujii

2016-12-01

Full Text Available Beryllium intermetallic compounds (beryllides are the most promising candidate materials for use as advanced neutron multipliers in future fusion reactors because of their low swelling and high stability at high temperatures. Recently, beryllium–titanium beryllide pebbles such as Be12Ti have been successfully fabricated using a novel granulation process. In this study, the fundamental aspects of the behavior of hydrogen isotopes in Be12Ti pebbles were investigated via thermal desorption spectroscopy and transmission electron microscopy. In addition, atomistic calculations using first principles electronic-structure methods were applied to determine the solution energy of hydrogen in Be12Ti. The results showed simpler and weaker hydrogen-trapping efficiency for Be12Ti than for pure Be.

Hydrogen production by thermal water splitting using a thermal plasma

International Nuclear Information System (INIS)

Boudesocque, N.; Lafon, C.; Girold, C.; Vandensteendam, C.; Baronnet, J.M.

2006-01-01

CEA has been working for more than 10 years in plasma technologies devoted to waste treatment: incineration, vitrification, gases and liquid treatment. Based on this experience, CEA experiments since several years an innovative route for hydrogen production by thermal water splitting, using a plasma as heat source. This new approach could be considered as an alternative to electrolysis for massive hydrogen production from water and electricity. This paper presents a brief state of the art of water thermal plasmas, showing the temperatures and quench velocity ranges technologically achievable today. Thermodynamic properties of a water plasma are presented and discussed. A kinetic computational model is presented, describing the behavior of splitted products during the quench in a plasma plume for various parameters, such as the quench rate. The model results are compared to gas analysis in the plasma plume obtained with in-situ sampling probe. The plasma composition measurements are issued from an Optical Emission Spectroscopic method (OES). The prediction of 30 % H 2 recovery with a 108 K.s -1 quench rate has been verified. A second experimentation has been performed: mass gas analysis, flowrate measurement and OES to study the 'behavior' and species in underwater electrical arc stricken between graphite electrodes. With this quench, a synthesis gas was produced with a content 55 % of hydrogen. (authors)

Hydrogen isotope behavior in the first wall of JT-60U after deuterium plasma operation

International Nuclear Information System (INIS)

Oya, Y.; Tanabe, T.; Oyaidzu, M.; Shibahara, T.; Sugiyama, K.; Yoshikawa, A.; Onishi, Y.; Hirohata, Y.; Ishimoto, Y.; Yagyu, J.; Arai, T.; Masaki, K.; Okuno, K.; Miya, N.; Tanaka, S.

2007-01-01

Retention of hydrogen isotopes in the carbon (isotropic graphite) first wall tiles of JT-60U was studied by secondary ion mass spectrometry and thermal desorption spectroscopy. The surface morphology and erosion/deposition profiles of the tiles were characterized using scanning electron microscope and X-ray photoelectron spectroscopy. The upper area is mainly eroded, while the bottom area of the inboard wall is dominated by deposition. In contrast to the divertor area, hydrogen isotope retention in the eroded wall area was generally larger than that in the deposition dominated area. Measured near surface concentrations of hydrogen isotopes in the wall tiles, as well as the D/H ratios, were a little higher than those in the divertor area. This indicates direct implantation of high-energy D from NBI into the first wall. The lower temperature of the first wall relative to the divertor tiles would reduce desorption and/or replacement of implanted D by subsequent D or H impingement

Thermal desorption remediation in relation to landfill disposal at isolated sites in northern Alberta

International Nuclear Information System (INIS)

Walker, G.; Henze, M.; Fernuik, N.; MacKinnon, B.; Nelson, D.

2005-01-01

Thermal desorption (TD) involves the application of heat to organic-contaminated soil to release and thermally destruct contaminants using high temperatures. An overview of the technique used in the remediation of diesel-contaminated sites was presented. The paper was divided into 2 parts, the first of which provided an overview of TD at 2 electric company sites with a total of 29,000 tonnes of diesel-contaminated soil. Site contamination occurred mainly through the loading, storage and dispensing of diesel fuel. Petroleum lubricants, polychlorinated biphenyls (PCBs), polycyclic aromatic hydrocarbons (PAHs), glycols and metals were among the other contaminants. Remediation work was comprised of dig and dump (DD) or thermal desorption (TD) treatment of contaminated soils as well as the removal of underground facilities including concrete foundations, screw anchors, storage tanks, pipelines and grounding grids. The TD process, and productivity with both clay and sand soil types was reviewed, and an analysis of direct, indirect and total costs was presented. Issues concerning planning, production rates, practical field experience and quality control procedures were discussed, in addition to limitations such the treatment's inability to remediate metals, sensitivity to soil water content, and water demands for soil processing. The second section described the role of TD in a staged remediation for 46,000 tonnes of diesel-contaminated soil at Fox Lake, a remote northern community accessible by winter road and ice bridges. The challenges of ice bridge construction and maintenance, excavation backfilling and soil transport at low temperature were reviewed. An outline of consultation processes with First Nations was presented, as well as details of site operations and soil hauling, truck restrictions and coordination over the ice bridge, alternate backfill sources, and TD soil treatment of the contaminated soil. 2 tabs

Concept study of a hydrogen containment process during nuclear thermal engine ground testing

Directory of Open Access Journals (Sweden)

Ten-See Wang

Full Text Available A new hydrogen containment process was proposed for ground testing of a nuclear thermal engine. It utilizes two thermophysical steps to contain the hydrogen exhaust. First, the decomposition of hydrogen through oxygen-rich combustion at higher temperature; second, the recombination of remaining hydrogen with radicals at low temperature. This is achieved with two unit operations: an oxygen-rich burner and a tubular heat exchanger. A computational fluid dynamics methodology was used to analyze the entire process on a three-dimensional domain. The computed flammability at the exit of the heat exchanger was less than the lower flammability limit, confirming the hydrogen containment capability of the proposed process. Keywords: Hydrogen decomposition reactions, Hydrogen recombination reactions, Hydrogen containment process, Nuclear thermal propulsion, Ground testing

Physisorption and desorption of H2, HD and D2 on amorphous solid water ice. Effect on mixing isotopologue on statistical population of adsorption sites.

Science.gov (United States)

Amiaud, Lionel; Fillion, Jean-Hugues; Dulieu, François; Momeni, Anouchah; Lemaire, Jean-Louis

2015-11-28

We study the adsorption and desorption of three isotopologues of molecular hydrogen mixed on 10 ML of porous amorphous water ice (ASW) deposited at 10 K. Thermally programmed desorption (TPD) of H2, D2 and HD adsorbed at 10 K have been performed with different mixings. Various coverages of H2, HD and D2 have been explored and a model taking into account all species adsorbed on the surface is presented in detail. The model we propose allows to extract the parameters required to fully reproduce the desorption of H2, HD and D2 for various coverages and mixtures in the sub-monolayer regime. The model is based on a statistical description of the process in a grand-canonical ensemble where adsorbed molecules are described following a Fermi-Dirac distribution.

Retention of hydrogen isotopes and helium in nickel

Energy Technology Data Exchange (ETDEWEB)

Okada, Mitsumasa; Sato, Rikiya; Yamaguchi, Kenji; Yamawaki, Michio [Tokyo Univ., Tokai, Ibaraki (Japan). Nuclear Engineering Research Lab.

1996-10-01

In the present study, a thin foil of nickel was irradiated by H{sub 2}{sup +}, D{sub 2}{sup +} and He{sup +} to a fluence of 1.2-6.0x10{sup 20}/m{sup 2} using the TBTS (Tritium Beam Test System) apparatus. The thermal desorption spectroscopy (TDS) technique was employed to evaluate the total amount of retained hydrogen isotope and helium atoms in nickel. In the spectra, two peaks appeared at 440-585K and 720-735K for helium. Hydrogen isotopes irradiation after helium preirradiation were found to enhance the helium release and to decrease the peak temperatures. Helium irradiation after hydrogen isotopes preirradiation were found to enhance the helium release, but the peak temperature showed little difference from that without preirradiation. (author)

BEHAVIOR OF THERMAL SPRAY COATINGS AGAINST HYDROGEN ATTACK

OpenAIRE

Vargas, Fabio; Latorre, Guillermo; Uribe, Iván

2003-01-01

The behavior of nickel and chrome alloys applied as thermal spray coatings to be used as protection against embrittlement by hydrogen is studied. Coatings were applied on a carbon steel substrate, under conditions that allow obtain different crystalline structures and porosity levels, in order to determine the effect of these variables on the hydrogen permeation kinetics and as a protection means against embrittlement caused this element. In order to establish behaviors as barriers and protec...

Hydriding and structural characteristics of thermally cycled and cold-worked V-0.5 at.%C alloy

International Nuclear Information System (INIS)

Chandra, Dhanesh; Sharma, Archana; Chellappa, Raja; Cathey, William N.; Lynch, Franklin E.; Bowman, Robert C.; Wermer, Joseph R.; Paglieri, Stephen N.

2008-01-01

High pressure hydrides of V 0.995 C 0.005 were thermally cycled between β 2 - and γ-phases hydrides for potential use in cryocoolers/heat pumps for space applications. The effect of addition of carbon to vanadium, on the plateau enthalpies of the high pressure β 2 + γ region is minimal. This is in contrast to the calculated plateau enthalpies for low pressure (α + β 1 ) mixed phases which showed a noticeable lowering of the values. Thermal cycling between β 2 -and γ-phase hydrides increased the absorption pressures but desorption pressure did not change significantly and the free energy loss due to hysteresis also increased. Hydriding of the alloy with prior cold-work increased the pressure hysteresis significantly and lowered the hydrogen capacity. In contrast to the alloy without any prior straining (as-cast), desorption pressure of the alloy with prior cold-work also decreased significantly. Microstrains, 2 > 1/2 , in the β 2 -phase lattice of the thermally cycled hydrides decreased after 778 cycles and the domain sizes increased. However, in the γ-phase, both the microstrains and the domain sizes decreased after thermal cycling indicating no particle size effect. The dehydrogenated α-phase after 778 thermal cycles also showed residual microstrains in the lattice, similar to those observed in intermetallic hydrides. The effect of thermal cycling (up to 4000 cycles between β 2 - and γ-phases) and cold working on absorption/desorption pressures, hydrogen storage capacity, microstrains, long-range strains, and domain sizes of β 2 - and γ-phase hydrides of V 0.995 C 0.005 alloys are presented

Hydrogenation of Phenylacetylene to Styrene on Pre-C_xH_y- and C-Covered Cu(111) Single Crystal Catalysts

International Nuclear Information System (INIS)

Sohn, Young Ku; Wei, Wei; White, John M.

2011-01-01

Thermal hydrogenation of phenylacetylene (PA, C_8H_6) to styrene (C_8H_8) on pre-C_xH_y- and C-covered Cu(111) single crystal substrates has been studied using temperature-programmed desorption (TPD) mass spectrometry. Chemisorbed PA with an acetylene group has been proved to be associated with hydrogen of pre-adsorbed C_xH_y to form styrene (104 amu) on Cu surface. For the parent (PA) mass (102 amu) TPD profile, the TPD peaks at 360 K and 410 K are assigned to chemisorbed vertically aligned PA and flat-lying cross-bridged PA, respectively (J. Phys. Chem. C 2007, 111, 5101). The relative I_3_6_0_K/I_4_1_0_K TPD ratio dramatically increases with increasing pre-adsorbed C_xH_y before dosing PA, while the ratio does not increase for pre-C-covered surface. For PA on pre-C_xH_y-covered Cu(111) surface, styrene desorption is enhanced relative to the parent PA desorption, while styrene formation is dramatically quenched on pre-C-covered (lack of adsorbed hydrogen nearby) surface. It appears that only cross-bridged PA associates with adsorbed hydrogen to form styrene that promptly desorbs at 410 K, while vertically aligned PA is less likely to participate in forming styrene

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.

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)

Reaction-diffusion modeling of hydrogen in beryllium

Energy Technology Data Exchange (ETDEWEB)

Wensing, Mirko; Matveev, Dmitry; Linsmeier, Christian [Forschungszentrum Juelich GmbH, Institut fuer Energie- und Klimaforschung - Plasmaphysik (Germany)

2016-07-01

Beryllium will be used as first-wall material for the future fusion reactor ITER as well as in the breeding blanket of DEMO. In both cases it is important to understand the mechanisms of hydrogen retention in beryllium. In earlier experiments with beryllium low-energy binding states of hydrogen were observed by thermal desorption spectroscopy (TDS) which are not yet well understood. Two candidates for these states are considered: beryllium-hydride phases within the bulk and surface effects. The retention of deuterium in beryllium is studied by a reaction rate approach using a coupled reaction diffusion system (CRDS)-model relying on ab initio data from density functional theory calculations (DFT). In this contribution we try to assess the influence of surface recombination.

Operable Unit 7-13/14 in situ thermal desorption treatability study work plan

International Nuclear Information System (INIS)

Shaw, P.; Nickelson, D.; Hyde, R.

1999-01-01

This Work Plan provides technical details for conducting a treatability study that will evaluate the application of in situ thermal desorption (ISTD) to landfill waste at the Subsurface Disposal Area (SDA) at the Idaho National Engineering and Environmental Laboratory (INEEL). ISTD is a form of thermally enhanced vapor vacuum extraction that heats contaminated soil and waste underground to raise its temperature and thereby vaporize and destroy most organics. An aboveground vapor vacuum collection and treatment system then destroys or absorbs the remaining organics and vents carbon dioxide and water to the atmosphere. The technology is a byproduct of an advanced oil-well thermal extraction program. The purpose of the ISTD treatability study is to fill performance-based data gaps relative to off-gas system performance, administrative feasibility, effects of the treatment on radioactive contaminants, worker safety during mobilization and demobilization, and effects of landfill type waste on the process (time to remediate, subsidence potential, underground fires, etc.). By performing this treatability study, uncertainties associated with ISTD as a selected remedy will be reduced, providing a better foundation of remedial recommendations and ultimate selection of remedial actions for the SDA

Metal-inorganic-organic matrices as efficient sorbents for hydrogen storage.

Science.gov (United States)

Azzouz, Abdelkrim; Nousir, Saadia; Bouazizi, Nabil; Roy, René

2015-03-01

Stabilization of metal nanoparticles (MNPs) without re-aggregation is a major challenge. An unprecedented strategy is developed for achieving high dispersion of copper(0) or palladium(0) on montmorillonite-supported diethanolamine or thioglycerol. This results in novel metal-inorganic-organic matrices (MIOM) that readily capture hydrogen at ambient conditions, with easy release under air stream. Hydrogen retention appears to involve mainly physical interactions, slightly stronger on thioglycerol-based MIOM (S-MIOM). Thermal enhancement of desorption suggests also a contribution of chemical interactions. The increase of hydrogen uptake with prolonged contact times arises from diffusion hindrance, which appears to be beneficial by favoring hydrogen entrapment. Even with compact structures, MIOMs act as efficient sorbents with much higher efficiency factor (1.14-1.17 mmol H 2 m(-2)) than many other sophisticated adsorbents reported in the literature. This opens new prospects for hydrogen storage and potential applications in microfluidic hydrogenation reactions. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

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

Characterisation of Dissolved Organic Carbon by Thermal Desorption - Proton Transfer Reaction - Mass Spectrometry

Science.gov (United States)

Materić, Dušan; Peacock, Mike; Kent, Matthew; Cook, Sarah; Gauci, Vincent; Röckmann, Thomas; Holzinger, Rupert

2017-04-01

Dissolved organic carbon (DOC) is an integral component of the global carbon cycle. DOC represents an important terrestrial carbon loss as it is broken down both biologically and photochemically, resulting in the release of carbon dioxide (CO2) to the atmosphere. The magnitude of this carbon loss can be affected by land management (e.g. drainage). Furthermore, DOC affects autotrophic and heterotrophic processes in aquatic ecosystems, and, when chlorinated during water treatment, can lead to the release of harmful trihalomethanes. Numerous methods have been used to characterise DOC. The most accessible of these use absorbance and fluorescence properties to make inferences about chemical composition, whilst high-performance size exclusion chromatography can be used to determine apparent molecular weight. XAD fractionation has been extensively used to separate out hydrophilic and hydrophobic components. Thermochemolysis or pyrolysis Gas Chromatography - Mass Spectrometry (GC-MS) give information on molecular properties of DOC, and 13C NMR spectroscopy can provide an insight into the degree of aromaticity. Proton Transfer Reaction - Mass Spectrometry (PTR-MS) is a sensitive, soft ionisation method suitable for qualitative and quantitative analysis of volatile and semi-volatile organic vapours. So far, PTR-MS has been used in various environmental applications such as real-time monitoring of volatile organic compounds (VOCs) emitted from natural and anthropogenic sources, chemical composition measurements of aerosols etc. However, as the method is not compatible with water, it has not been used for analysis of organic traces present in natural water samples. The aim of this work was to develop a method based on thermal desorption PTR-MS to analyse water samples in order to characterise chemical composition of dissolved organic carbon. We developed a clean low-pressure evaporation/sublimation system to remove water from samples and thermal desorption system to introduce

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.

Ink dating using thermal desorption and gas chromatography / mass spectrometry: comparison of results obtained in two laboratories

OpenAIRE

Koenig, A.; Bügler, J.; Kirsch, D.; Köhler, F.; Weyermann, C.

2015-01-01

Recent ink dating methods focused mainly on changes in solvent amounts occurring over time. A promising method was developed at the Landeskriminalamt of Munich using thermal desorption (TD) followed by gas chromatography / mass spectrometry (GC/MS) analysis. Sequential extractions of the phenoxyethanol present in ballpoint pen ink entries were carried out at two different temperatures. This method is applied in forensic practice and is currently implemented in several laboratories participati...

Numerical methods for calculating thermal residual stresses and hydrogen diffusion

International Nuclear Information System (INIS)

Leblond, J.B.; Devaux, J.; Dubois, D.

1983-01-01

Thermal residual stresses and hydrogen concentrations are two major factors intervening in cracking phenomena. These parameters were numerically calculated by a computer programme (TITUS) using the FEM, during the deposition of a stainless clad on a low-alloy plate. The calculation was performed with a 2-dimensional option in four successive steps: thermal transient calculation, metallurgical transient calculation (determination of the metallurgical phase proportions), elastic-plastic transient (plain strain conditions), hydrogen diffusion transient. Temperature and phase dependence of hydrogen diffusion coefficient and solubility constant. The following results were obtained: thermal calculations are very consistent with experiments at higher temperatures (due to the introduction of fusion and solidification latent heats); the consistency is not as good (by 70 degrees) for lower temperatures (below 650 degrees C); this was attributed to the non-introduction of gamma-alpha transformation latent heat. The metallurgical phase calculation indicates that the heat affected zone is almost entirely transformed into bainite after cooling down (the martensite proportion does not exceed 5%). The elastic-plastic calculations indicate that the stresses in the heat affected zone are compressive or slightly tensile; on the other hand, higher tensile stresses develop on the boundary of the heat affected zone. The transformation plasticity has a definite influence on the final stress level. The return of hydrogen to the clad during the bainitic transformation is but an incomplete phenomenon and the hydrogen concentration in the heat affected zone after cooling down to room temperature is therefore sufficient to cause cold cracking (if no heat treatment is applied). Heat treatments are efficient in lowering the hydrogen concentration. These results enable us to draw preliminary conclusions on practical means to avoid cracking. (orig.)

In-situ TEM on (de)hydrogenation of Pd at 0.5–4.5 bar hydrogen pressure and 20–400°C

International Nuclear Information System (INIS)

Yokosawa, Tadahiro; Alan, Tuncay; Pandraud, Gregory; Dam, Bernard; Zandbergen, Henny

2012-01-01

We have developed a nanoreactor, sample holder and gas system for in-situ transmission electron microscopy (TEM) of hydrogen storage materials up to at least 4.5 bar. The MEMS-based nanoreactor has a microheater, two electron-transparent windows and a gas inlet and outlet. The holder contains various O-rings to have leak-tight connections with the nanoreactor. The system was tested with the (de)hydrogenation of Pd at pressures up to 4.5 bar. The Pd film consisted of islands being 15 nm thick and 50–500 nm wide. In electron diffraction mode we observed reproducibly a crystal lattice expansion and shrinkage owing to hydrogenation and dehydrogenation, respectively. In selected-area electron diffraction and bright/dark-field modes the (de)hydrogenation of individual Pd particles was followed. Some Pd islands are consistently hydrogenated faster than others. When thermally cycled, thermal hysteresis of about 10–16 °C between hydrogen absorption and desorption was observed for hydrogen pressures of 0.5–4.5 bar. Experiments at 0.8 bar and 3.2 bar showed that the (de)hydrogenation temperature is not affected by the electron beam. This result shows that this is a fast method to investigate hydrogen storage materials with information at the nanometer scale. -- Highlights: ► In-situ TEM experiments up to 4.5 bar. ► In-situ TEM on a hydrogen storage material at pressures used in practice. ► No electron beam effect on (de)hydrogenation. ► In-situ TEM allows for fast screening of hydrogen storage materials.

Thermal characteristics during hydrogen fueling process of type IV cylinder

Energy Technology Data Exchange (ETDEWEB)

Kim, Sung Chan [Department of Fire and Disaster Prevention, Kyungil University, 33, Buhori, Hayang, Kyungsan 712-701 (Korea); Lee, Seung Hoon; Yoon, Kee Bong [Department of Mechanical Engineering, Chung Ang University, 221, Huksuk, Dongjak, Seoul 156-756 (Korea)

2010-07-15

Temperature increase during hydrogen fueling process is a significant safety concern of a high pressure hydrogen vessel. Hence, thermal characteristics of a Type IV cylinder during hydrogen filling process need to be understood. In this study, a series of experiments were conducted to quantify the temperature change of the cylinder during hydrogen filling to 35 MPa. Computational fluid dynamics (CFD) analysis was also conducted to simulate the conditions of the experiments. The results predicted by the CFD analysis show reasonable agreement with the experiments and the discrepancy between the CFD results and experimental results decrease with higher initial gas pressures. The upper and the lower parts of the vessel showed a temperature difference in the vertical direction. The upper gas temperature was higher than that of the lower part due to the buoyancy effect in the vessel. The maximum gas temperature was higher than the maximum temperature allowed in the ISO safety code (85 C) for the case in which the vessel was pressurized from 0 MPa to 35 MPa. This work contributes to the understanding of the thermal flow characteristics of the hydrogen filling process and notes that additional efforts should be made to guarantee the safety of a type IV cylinder during the hydrogen fueling process. (author)

Leidenfrost Phenomenon-assisted Thermal Desorption (LPTD) and Its Application to Open Ion Sources at Atmospheric Pressure Mass Spectrometry

Science.gov (United States)

Saha, Subhrakanti; Chen, Lee Chuin; Mandal, Mridul Kanti; Hiraoka, Kenzo

2013-03-01

This work describes the development and application of a new thermal desorption technique that makes use of the Leidenfrost phenomenon in open ion sources at atmospheric pressure for direct mass spectrometric detection of ultratrace levels of illicit, therapeutic, and stimulant drugs, toxicants, and peptides (molecular weight above 1 kDa) in their unaltered state from complex real world samples without or with minor sample pretreatment. A low temperature dielectric barrier discharge ion source was used throughout the experiments and the analytical figures of merit of this technique were investigated. Further, this desorption technique coupled with other ionization sources such as electrospray ionization (ESI) and dc corona discharge atmospheric pressure chemical ionization (APCI) in open atmosphere was also investigated. The use of the high-resolution `Exactive Orbitrap' mass spectrometer provided unambiguous identification of trace levels of the targeted compounds from complex mixtures and background noise; the limits of detection for various small organic molecules and peptides treated with this technique were at the level of parts per trillion and 10-9 M, respectively. The high sensitivity of the present technique is attributed to the spontaneous enrichment of analyte molecules during the slow evaporation of the solvent, as well as to the sequential desorption of molecules from complex mixtures based on their volatilities. This newly developed desorption technique is simple and fast, while molecular ions are observed as the major ions.

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

Thermal modeling of nickel-hydrogen battery cells operating under transient orbital conditions

Science.gov (United States)

Schrage, Dean S.

1991-01-01

An analytical study of the thermal operating characteristics of nickel-hydrogen battery cells is presented. Combined finite-element and finite-difference techniques are employed to arrive at a computationally efficient composite thermal model representing a series-cell arrangement operating in conjunction with a radiately coupled baseplate and coldplate thermal bus. An aggressive, low-mass design approach indicates that thermal considerations can and should direct the design of the thermal bus arrangement. Special consideration is given to the potential for mixed conductive and convective processes across the hydrogen gap. Results of a compressible flow model are presented and indicate the transfer process is suitably represented by molecular conduction. A high-fidelity thermal model of the cell stack (and related components) indicates the presence of axial and radial temperature gradients. A detailed model of the thermal bus reveals the thermal interaction of individual cells and is imperative for assessing the intercell temperature gradients.

Biological functioning of PAH-polluted and thermal desorption-treated soils assessed by fauna and microbial bioindicators.

Science.gov (United States)

Cébron, Aurélie; Cortet, Jérôme; Criquet, Stéven; Biaz, Asmaa; Calvert, Virgile; Caupert, Cécile; Pernin, Céline; Leyval, Corinne

2011-11-01

A large number of soil bioindicators were used to assess biological diversity and activity in soil polluted with polycyclic aromatic hydrocarbons (PAHs) and the same soil after thermal desorption (TD) treatment. Abundance and biodiversity of bacteria, fungi, protozoa, nematodes and microarthropods, as well as functional parameters such as enzymatic activities and soil respiration, were assessed during a two year period of in situ monitoring. We investigated the influence of vegetation (spontaneous vegetation and Medicago sativa) and TD treatment on biological functioning. Multivariate analysis was performed to analyze the whole data set. A principal response curve (PRC) technique was used to evaluate the different treatments (various vegetation and contaminated vs. TD soil) contrasted with control (bare) soil over time. Our results indicated the value of using a number of complementary bioindicators, describing both diversity and functions, to assess the influence of vegetation on soil and discriminate polluted from thermal desorption (TD)-treated soil. Plants had an influence on the abundance and activity of all organisms examined in our study, favoring the whole trophic chain development. However, although TD-treated soil had a high abundance and diversity of microorganisms and fauna, enzymatic activities were weak because of the strong physical and chemical modifications of this soil. Copyright © 2011 Institut Pasteur. Published by Elsevier Masson SAS. All rights reserved.

Laser-induced desorption determinations of surface diffusion on Rh(111)

International Nuclear Information System (INIS)

Seebauer, E.G.; Schmidt, L.D.

1987-01-01

Surface diffusion of hydrogen, deuterium and CO on Rh(111) has been investigated by laser-induced thermal desorption (LITD) and compared with previous results for these species on Pt(111) and on other metals. For deuterium in the coverage range 0.02 0 - 8 x 10 -2 cm 2 /s, with a diffusion activation energy 3.7 0 rises from 10 -3 to 10 -2 cm 2 /s between θ = 0.01 and 0.40. Values of E/sub diff/ on different surfaces appear to correlate with differences in heats of adsorption in different binding states which form saddle point configurations in surface diffusion. In addition, oxidation reactions on Rh and on several other transition metal surfaces may be limited to CO or H surface diffusion. 30 refs., 3 figs., 1 tab

Helium implanted Eurofer97 characterized by positron beam Doppler broadening and Thermal Desorption Spectroscopy

Energy Technology Data Exchange (ETDEWEB)

Carvalho, I., E-mail: i.carvalho@m2i.nl [Materials Innovation Institute (M2i), Delft (Netherlands); Schut, H. [Delft University of Technology, Faculty of Applied Sciences, Delft (Netherlands); Fedorov, A.; Luzginova, N. [Nuclear Research and Consultancy Group (NRG), Petten (Netherlands); Desgardin, P. [CEMHTI-CNRS, 3A Rue de la Férolerie, 45071 Orléans Cedex (France); Sietsma, J. [Delft University of Technology, Faculty of Mechanical, Maritime and Materials Engineering, Delft (Netherlands)

2013-11-15

Reduced Activation Ferritic/Martensitic steels are being extensively studied because of their foreseen application in fusion and Generation IV fission reactors. To produce irradiation induced defects, Eurofer97 samples were implanted with helium at energies of 500 keV and 2 MeV and doses of 1 × 10{sup 15}–10{sup 16} He/cm{sup 2}, creating atomic displacements in the range 0.07–0.08 dpa. The implantation induced defects were characterized by positron beam Doppler Broadening (DB) and Thermal Desorption Spectroscopy (TDS). Results show that up to ∼600 K peaks that can be attributed to He desorption from overpressured He{sub n}V{sub m} (n > m) clusters and vacancy assisted mechanism in the case of helium in the substitutional position. The temperature range 600–1200 K is related to the formation of larger clusters He{sub n}V{sub m} (n < m). The dissociation of the HeV and the phase transition attributed to a sharp peak in the TDS spectra at 1200 K. Above this temperature, the release of helium from bubbles is observed.

Thermal energy distribution analysis for hydrogen production in RGTT200K conceptual design

International Nuclear Information System (INIS)

Tumpal Pandiangan; Ign Djoko Irianto

2011-01-01

RGTT200K is a high temperature gas-cooled reactor (HTGR) which conceptually designed for power generation, hydrogen production and desalination. Hydrogen production process in this design uses thermochemical method of Iodine-Sulphur. To increase the thermal conversion efficiency in hydrogen production installations, it needs to design a thermal energy distribution and temperature associated with the process of thermo-chemical processes in the method of Iodine-Sulphur. In this method there are 7 kinds of processes: (i) H 2 SO4 decomposition reaction (ii) treatment of vaporization (iii) treatment of pre vaporizer (iv) treatment of flash 4 (v) treatment of decomposition of HI (vi) treatment of the flash 1-3 and (vii) Bunsen reaction. To regulate the distribution of energy and temperature appropriate to the needs of each process used 3 pieces of heat exchanger (HE). Calculation of energy distribution through the distribution of helium gas flow has been done with Scilab application programs, so that can know the distribution of thermal energy for production of 1 mole of hydrogen. From this model, it can calculate the thermal energy requirement for production of hydrogen at the desired capacity. In the conceptual design of RGTT200K, helium discharge has been designed by 20 kg/s, so that an efficient hydrogen production capacity needed to produce 15347.8 for 21.74 mole of H 2 . (author)

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

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)

Thermally regenerative hydrogen/oxygen fuel cell power cycles

Science.gov (United States)

Morehouse, J. H.

1986-01-01

Two innovative thermodynamic power cycles are analytically examined for future engineering feasibility. The power cycles use a hydrogen-oxygen fuel cell for electrical energy production and use the thermal dissociation of water for regeneration of the hydrogen and oxygen. The TDS (thermal dissociation system) uses a thermal energy input at over 2000 K to thermally dissociate the water. The other cycle, the HTE (high temperature electrolyzer) system, dissociates the water using an electrolyzer operating at high temperature (1300 K) which receives its electrical energy from the fuel cell. The primary advantages of these cycles is that they are basically a no moving parts system, thus having the potential for long life and high reliability, and they have the potential for high thermal efficiency. Both cycles are shown to be classical heat engines with ideal efficiency close to Carnot cycle efficiency. The feasibility of constructing actual cycles is investigated by examining process irreversibilities and device efficiencies for the two types of cycles. The results show that while the processes and devices of the 2000 K TDS exceed current technology limits, the high temperature electrolyzer system appears to be a state-of-the-art technology development. The requirements for very high electrolyzer and fuel cell efficiencies are seen as determining the feasbility of the HTE system, and these high efficiency devices are currently being developed. It is concluded that a proof-of-concept HTE system experiment can and should be conducted.

Thermal Desorption Analysis of Effective Specific Soil Surface Area

Science.gov (United States)

Smagin, A. V.; Bashina, A. S.; Klyueva, V. V.; Kubareva, A. V.

2017-12-01

A new method of assessing the effective specific surface area based on the successive thermal desorption of water vapor at different temperature stages of sample drying is analyzed in comparison with the conventional static adsorption method using a representative set of soil samples of different genesis and degree of dispersion. The theory of the method uses the fundamental relationship between the thermodynamic water potential (Ψ) and the absolute temperature of drying ( T): Ψ = Q - aT, where Q is the specific heat of vaporization, and a is the physically based parameter related to the initial temperature and relative humidity of the air in the external thermodynamic reservoir (laboratory). From gravimetric data on the mass fraction of water ( W) and the Ψ value, Polyanyi potential curves ( W(Ψ)) for the studied samples are plotted. Water sorption isotherms are then calculated, from which the capacity of monolayer and the target effective specific surface area are determined using the BET theory. Comparative analysis shows that the new method well agrees with the conventional estimation of the degree of dispersion by the BET and Kutilek methods in a wide range of specific surface area values between 10 and 250 m2/g.

Hydrogen retention studies on lithiated tungsten exposed to glow discharge plasmas under varying lithiation environments using Thermal Desorption Spectroscopy and mass spectrometry

Energy Technology Data Exchange (ETDEWEB)

Castro, A. de, E-mail: alfonso.decastro@ciemat.es [Fusion National Laboratory-CIEMAT, Av Complutense 40, 28040 Madrid (Spain); Valson, P. [Max-Planck-Institut für Plasmaphysik, Wendelsteinstraße 1, 17491 Greifswald (Germany); Tabarés, F.L. [Fusion National Laboratory-CIEMAT, Av Complutense 40, 28040 Madrid (Spain)

2017-04-15

For the design of a Fusion Reactor based on a liquid lithium divertor target and a tungsten first wall at high temperature, the interaction of the wall material with plasmas of significant lithium content must be assessed, as issues like fuel retention, tungsten embrittlement and enhanced sputtering may represent a showstopper for the selection of the first wall material compatible with the presence of liquid metal divertor. In this work we address this topic for the first time at the laboratory level, hot W samples (100 °C) have been exposed to Glow Discharges of H{sub 2} or Li-seeded H{sub 2} followed by in situ thermal desorption studies (TDS) of the uptake of H{sub 2} on the samples. Pure and pre-lithiated tungsten was investigated in order to evaluate the differential effect of Li ion implantation on H retention. Global particle balance was also used for the determination of trapped H into the full W wall of the plasma chamber. A factor of 3-4 lower retention was deduced for samples and main W wall exposed to H/Li plasma than that measured on pre-lithiated W.

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.

Thermal neutron diffusion parameters dependent on the flux energy distribution in finite hydrogenous media

International Nuclear Information System (INIS)

Drozdowicz, K.

1999-01-01

Macroscopic parameters for a description of the thermal neutron transport in finite volumes are considered. A very good correspondence between the theoretical and experimental parameters of hydrogenous media is attained. Thermal neutrons in the medium possess an energy distribution, which is dependent on the size (characterized by the geometric buckling) and on the neutron transport properties of the medium. In a hydrogenous material the thermal neutron transport is dominated by the scattering cross section which is strongly dependent on energy. A monoenergetic treatment of the thermal neutron group (admissible for other materials) leads in this case to a discrepancy between theoretical and experimental results. In the present paper the theoretical definitions of the pulsed thermal neutron parameters (the absorption rate, the diffusion coefficient, and the diffusion cooling coefficient) are based on Nelkin's analysis of the decay of a neutron pulse. Problems of the experimental determination of these parameters for a hydrogenous medium are discussed. A theoretical calculation of the pulsed parameters requires knowledge of the scattering kernel. For thermal neutrons it is individual for each hydrogenous material because neutron scattering on hydrogen nuclei bound in a molecule is affected by the molecular dynamics (characterized with internal energy modes which are comparable to the incident neutron energy). Granada's synthetic model for slow-neutron scattering is used. The complete up-dated formalism of calculation of the energy transfer scattering kernel after this model is presented in the paper. An influence of some minor variants within the model on the calculated differential and integral neutron parameters is shown. The theoretical energy-dependent scattering cross section (of Plexiglas) is compared to experimental results. A particular attention is paid to the calculation of the diffusion cooling coefficient. A solution of an equation, which determines the

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

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 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.

Coverage dependent desorption dynamics of deuterium on Si(100) surfaces: interpretation with a diffusion-promoted desorption model.

Science.gov (United States)

Matsuno, T; Niida, T; Tsurumaki, H; Namiki, A

2005-01-08

We studied coverage dependence of time-of-flight (TOF) spectra of D2 molecules thermally desorbed from the D/Si(100) surface. The mean translational energies Et of desorbed D2 molecules were found to increase from 0.20+/-0.05 eV to 0.40+/-0.04 eV as the desorption coverage window was decreased from 1.0 ML> or =thetaD> or =0.9 ML to 0.2 ML> or =thetaD> or =0 ML, being consistent with the kinetics switch predicted in the interdimer mechanism. The measured TOF spectra were deconvoluted into 2H, 3H, and 4H components by a curve fitting method along the principle of detailed balance. As a result, it turned out that the desorption kinetics changes from the 4H to the 3H situation at high coverage above thetaD=0.9 ML, while the 2H desorption is dominant for a quite wide coverage region up to thetaD=0.8 ML. A dynamic desorption mechanism by which the desorption is promoted by D-atom diffusion to dangling bonds was proposed. 2005 American Institute of Physics.

Kinetic Monte Carlo study on the evolution of silicon surface roughness under hydrogen thermal treatment

Energy Technology Data Exchange (ETDEWEB)

Wang, Gang; Wang, Yu; Wang, Junzhuan; Pan, Lijia; Yu, Linwei; Zheng, Youdou; Shi, Yi, E-mail: yshi@nju.edu.cn

2017-08-31

Highlights: • The KMC method is adopted to investigate the relationships between surface evolution and hydrogen thermal treatment conditions. • The reduction in surface roughness is divided into two stages at relatively low temperatures, both exhibiting exponential dependence on the time. • The optimized surface structure can be obtained by precisely adjusting thermal treatment temperatures and hydrogen pressures. - Abstract: The evolution of a two-dimensional silicon surface under hydrogen thermal treatment is studied by kinetic Monte Carlo simulations, focusing on the dependence of the migration behaviors of surface atoms on both the temperature and hydrogen pressure. We adopt different activation energies to analyze the influence of hydrogen pressure on the evolution of surface morphology at high temperatures. The reduction in surface roughness is divided into two stages, both exhibiting exponential dependence on the equilibrium time. Our results indicate that a high hydrogen pressure is conducive to obtaining optimized surfaces, as a strategy in the applications of three-dimensional devices.

HR-EELS study of hydrogen bonding configuration, chemical and thermal stability of detonation nanodiamond films

Energy Technology Data Exchange (ETDEWEB)

Michaelson, Sh.; Akhvlediani, R. [Schulich Faculty of Chemistry, Technion-Israel Institute of Technology, Haifa 32000 (Israel); Petit, T.; Girard, H.A.; Arnault, J.C. [CEA, LIST, Diamond Sensors Laboratory, F-91191 Gif sur Yvette (France); Hoffman, A., E-mail: choffman@tx.technion.ac.il [Schulich Faculty of Chemistry, Technion-Israel Institute of Technology, Haifa 32000 (Israel)

2014-06-01

Nano-diamond films composed of 3–10 nm grains prepared by the detonation method and deposited onto silicon substrates by drop-casting were examined by high resolution electron energy loss spectroscopy (HR-EELS), X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM) and secondary ion mass spectroscopy (SIMS). The impact of (i) ex-situ ambient annealing at 400 °C and (ii) ex-situ hydrogenation on hydrogen bonding and its thermal stability were examined. In order to clarify the changes in hydrogen bonding configuration detected on the different surfaces as a function of thermal annealing, in-situ hydrogenation by thermally activated atomic hydrogen was performed and examined. This study provides direct evidence that the exposure to ambient conditions and medium temperature ambient annealing have a pronounced effect on the hydrogen-carbon bonding configuration onto the nano-diamond surfaces. In-situ 1000 °C annealing results in irreversible changes of the film surface and partial nano-diamond silicidation.

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.

Quantification of Selected Vapour-Phase Compounds using Thermal Desorption-Gas Chromatography

Directory of Open Access Journals (Sweden)

McLaughlin DWJ

2014-12-01

Full Text Available A robust method for the analysis of selected vapour phase (VP compounds in mainstream smoke (MSS is described. Cigarettes are smoked on a rotary smoking machine and the VP that passes through the Cambridge filter pad collected in a TedlarA¯ bag. On completion of smoking, the bag contents are sampled onto an adsorption tube containing a mixed carbon bed. The tube is subsequently analysed on an automated thermal desorption (TD system coupled to a gas chromatography-flame ionization detector (GC-FID using a PoraPLOT-Q column. Quantification of 14 volatile compounds including the major carbonyls is achieved. Details of the method validation data are included in this paper. This method has been used to analyse the VP of cigarette MSS over a wide range of ‘tar’ deliveries and configurations with excellent repeatability. Results for the University of Kentucky reference cigarette 1R4F are in good agreement with reported values.

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.)

Optical and thermal energy discharge from tritiated solid hydrogen

International Nuclear Information System (INIS)

Magnotta, F.; Mapoles, E.R.; Collins, G.W.; Souers, P.C.

1991-01-01

The authors are investigating mechanisms of energy storage and release in tritiated solid hydrogens, by a variety of techniques including ESR, NMR and thermal and optical emission. The nuclear decay of a triton in solid hydrogen initiates the conversion of nuclear energy into stored chemical energy by producing unpaired hydrogen atoms which are trapped within the molecular lattice. The ability to store large quantities of atoms in this manner has been demonstrated and can serve as a basis for new forms of high energy density materials. This paper presents preliminary results of a study of the optical emission from solid hydrogen containing tritium over the visible and near infrared (NIR) spectral regions. Specifically, they have studied optical emission from DT and T 2 using CCD, silicon diode and germanium diode arrays. 8 refs., 6 figs

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)

Removal of Persistent Organic Pollutants from a Solid Matrix by Thermal Desorption Technology Using Conventional and Microwave Heating

Czech Academy of Sciences Publication Activity Database

Mašín, P.; Hendrych, J.; Kroužek, J.; Kubal, M.; Kochánková, L.; Sobek, Jiří

2013-01-01

Roč. 22, č. 7A (2013), s. 2017-2021 ISSN 1018-4619. [International Conference on Environmental Management , Engineering, Planning and Economics (CEMEPE 2011) & SECOTOX Conference /3./. Skiathos Island, 19.06.2011-24.06.2011] Grant - others:GA MŽP(CZ) SP/2f3/133/08 Institutional support: RVO:67985858 Keywords : thermal desorption * microwave heating * remediation * persistent pollutants * pilot scale Subject RIV: CI - Industrial Chemistry, Chemical Engineering Impact factor: 0.527, year: 2013

Universal scaling for biomolecule desorption induced by swift heavy ions

International Nuclear Information System (INIS)

Szenes, G.

2005-01-01

A thermal activation mechanism is proposed for the desorption of biomolecules. Good agreement is found with the experiments in a broad range of the electronic stopping power. The activation energies of desorption U are 0.33, 1.57 and 5.35 eV for positive, negative and neutral leucine molecules, respectively, and 2.05 eV for positive ergosterol molecules. The desorption of valine clusters is analyzed. The magnitude of the specific heat shows that the internal degrees of freedom are not excited up to the moment of desorption. The effect of irradiation temperature and of ion velocity on the desorption yield is discussed on the basis of the author's model. The scaling function derived in the model for the desorption of biomolecules is applied also to the sputtering of SiO 2 and U = 0.42 eV is obtained

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.

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.

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....

Performance evaluation of a thermal desorption/gas chromatographic/mass spectrometric method for the characterization of waste tank headspace samples

International Nuclear Information System (INIS)

Ma, C.Y.; Skeen, J.T.; Dindal, A.B.; Bayne, C.K.; Jenkins, R.A.

1997-01-01

A thermal desorption/gas chromatography/mass spectrometry (TD/GC/MS) method was validated for the determination of volatile organic compounds collected on carbonaceous triple sorbent traps and applied to characterize samples of headspace gases collected from underground nuclear waste storage tanks at the U.S. Department of Energy's Hanford site, in Richland, WA. Method validation used vapor-phase standards generated from 25 target analytes, including alkanes, alkyl alcohols, alkyl ketones, alkylated aromatics, and alkyl nitriles. The target analytes represent a group of compounds identified in one of the most problematic tanks. TD/GC/MS was carried out with modified injectors. Performance was characterized based on desorption efficiency, reproducibility, stability, and linearity of the calibration, method detection limits, preanalytical holding time, and quality control limits for surrogate standard recoveries. Desorption efficiencies were all greater than 82%, and the majority of the analytes (23 out of 25) had reproducibility values less than 24% near the method detection levels. The method was applied to the analysis of a total of 305 samples collected from the headspaces of 48 underground waste storge tanks. Quality control procedures were implemented to monitor sampling and TD/GC/MS method. 33 refs., 2 figs., 4 tabs

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.

Thermal desorption treatability test conducted with VAC*TRAX Unit

International Nuclear Information System (INIS)

1996-01-01

In 1992, Congress passed the Federal Facilities Compliance Act, requiring the U.S. Department of Energy (DOE) to treat and dispose of its mixed waste in accordance with Resource Conservation and Recovery Act (RCRA) treatment standards. In response to the need for mixed-waste treatment capacity, where off-site commercial treatment facilities do not exist or cannot be used, the DOE Albuquerque Operations Office (DOE-AL) organized a Treatment Selection Team to match mixed waste with treatment options and develop a strategy for treatment of mixed waste. DOE-AL manages nine sites with mixed-waste inventories. The Treatment Selection Team determined a need to develop mobile treatment units (MTUs) to treat waste at the sites where the wastes are generated. Treatment processes used for mixed wastes must remove the hazardous component (i.e., meet RCRA treatment standards) and contain the radioactive component in a form that will protect the worker, public, and environment. On the basis of the recommendations of the Treatment Selection Team, DOE-AL assigned projects to the sites to bring mixed-waste treatment capacity on-line. The three technologies assigned to the DOE Grand Junction Projects Office (DOE-GJPO) include thermal desorption (TD), evaporative oxidation, and waste water evaporation

Hydrogenation of Phenylacetylene to Styrene on Pre-C{sub x}H{sub y}- and C-Covered Cu(111) Single Crystal Catalysts

Energy Technology Data Exchange (ETDEWEB)

Sohn, Young Ku [Yeungnam University, Gyeongsan (Korea, Republic of); Wei, Wei; White, John M. [The University of Texas at Austin, Texas (United States)

2011-05-15

Thermal hydrogenation of phenylacetylene (PA, C{sub 8}H{sub 6}) to styrene (C{sub 8}H{sub 8}) on pre-C{sub x}H{sub y}- and C-covered Cu(111) single crystal substrates has been studied using temperature-programmed desorption (TPD) mass spectrometry. Chemisorbed PA with an acetylene group has been proved to be associated with hydrogen of pre-adsorbed C{sub x}H{sub y} to form styrene (104 amu) on Cu surface. For the parent (PA) mass (102 amu) TPD profile, the TPD peaks at 360 K and 410 K are assigned to chemisorbed vertically aligned PA and flat-lying cross-bridged PA, respectively (J. Phys. Chem. C 2007, 111, 5101). The relative I{sub 360K}/I{sub 410K} TPD ratio dramatically increases with increasing pre-adsorbed C{sub x}H{sub y} before dosing PA, while the ratio does not increase for pre-C-covered surface. For PA on pre-C{sub x}H{sub y}-covered Cu(111) surface, styrene desorption is enhanced relative to the parent PA desorption, while styrene formation is dramatically quenched on pre-C-covered (lack of adsorbed hydrogen nearby) surface. It appears that only cross-bridged PA associates with adsorbed hydrogen to form styrene that promptly desorbs at 410 K, while vertically aligned PA is less likely to participate in forming styrene.

Hydrogen bonding-assisted thermal conduction in β-sheet crystals of spider silk protein

Science.gov (United States)

Zhang, Lin; Chen, Teli; Ban, Heng; Liu, Ling

2014-06-01

Using atomistic simulations, we demonstrate that β-sheet, an essential component of spider silk protein, has a thermal conductivity 1-2 orders of magnitude higher than that of some other protein structures reported in the literature. In contrast to several other nanostructured materials of similar bundled/layered structures (e.g. few-layer graphene and bundled carbon nanotubes), the β-sheet is found to uniquely feature enhanced thermal conductivity with an increased number of constituting units, i.e. β-strands. Phonon analysis identifies inter-β-strand hydrogen bonding as the main contributor to the intriguing phenomenon, which prominently influences the state of phonons in both low- and high-frequency regimes. A thermal resistance model further verifies the critical role of hydrogen bonding in thermal conduction through β-sheet structures.Using atomistic simulations, we demonstrate that β-sheet, an essential component of spider silk protein, has a thermal conductivity 1-2 orders of magnitude higher than that of some other protein structures reported in the literature. In contrast to several other nanostructured materials of similar bundled/layered structures (e.g. few-layer graphene and bundled carbon nanotubes), the β-sheet is found to uniquely feature enhanced thermal conductivity with an increased number of constituting units, i.e. β-strands. Phonon analysis identifies inter-β-strand hydrogen bonding as the main contributor to the intriguing phenomenon, which prominently influences the state of phonons in both low- and high-frequency regimes. A thermal resistance model further verifies the critical role of hydrogen bonding in thermal conduction through β-sheet structures. Electronic supplementary information (ESI) available: Structure of the β-sheets, computational model, determination of area and temperature gradient, and additional phonon DOS results. See DOI: 10.1039/c4nr01195c

Plasma thermal conversion of bio-oil for hydrogen production

International Nuclear Information System (INIS)

Guenadou, David; Lorcet, Helene; Peybernes, Jean; Catoire, Laurent; Osmont, Antoine; Gokalp, Iskender

2012-01-01

Numerous processes exist or are proposed for the energetic conversion of biomass. The use of thermal plasma is proposed in the frame of the GALACSY project for the conversion of bio-oil to hydrogen and carbon monoxide. For this purpose, an experimental apparatus has been built. The feasibility of this conversion at very high temperature, as encountered in thermal plasma, is examined both experimentally and numerically. This zero dimensional study tends to show that a high temperature (around 2500 K or above) is needed to ensure a high yield of hydrogen (about 50 mol%) and about 95 mol% of CO+H 2 . Predicted CO+H 2 yield and CO/H 2 ratio are consistent with measurements. It is also expected that the formation of particles and tars is hampered. Thermodynamic data of selected bio-oil components are provided in the CHEMKINNASA format. (authors)

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

Non-isothermal kinetics of the thermal desorption of mercury from a contaminated soil

Directory of Open Access Journals (Sweden)

López, Félix A.

2014-03-01

Full Text Available The Almadén mining district (Ciudad Real, Spain was the largest cinnabar (mercury sulphide mine in the world. Its soils have high levels of mercury a consequence of its natural lithology, but often made much worse by its mining history. The present work examines the thermal desorption of two contaminated soils from the Almadén area under non-isothermal conditions in a N2 atmosphere, using differential scanning calorimetry (DSC. DSC was performed at different heating rates between room temperature and 600 °C. Desorption temperatures for different mercury species were determined. The Friedman, Flynn-Wall-Ozawa and Coasts–Redfern methods were employed to determine the reaction kinetics from the DSC data. The activation energy and pre-exponential factor for mercury desorption were calculated.El distrito minero de Almadén (Ciudad Real, España tiene la mayor mina de cinabrio (sulfuro de mercurio del mundo. Sus suelos tienen altos niveles de mercurio como consecuencia de su litología natural, pero a menudo su contenido en mercurio es mucho más alto debido a la historia minera de la zona. Este trabajo examina la desorción térmica de dos suelos contaminados procedentes de Almadén bajo condiciones isotérmicas en atmósfera de N2, empleando calorimetría diferencial de barrido (DSC. La calorimetría se llevó a cabo a diferentes velocidades de calentamiento desde temperatura ambiente hasta 600 °C. Se determinaron las diferentes temperaturas de desorción de las especies de mercurio presentes en los suelos. Para determinar la cinética de reacción a partir de los datos de DSC se utilizaron los métodos de Friedman, Flynn-Wall-Ozawa y Coasts–Redfern. Además se calcularon las energías de activación y los factores pre-exponenciales para la desorción del mercurio.

Retention of Hydrogen Isotopes in Divertor Tiles Used in JT-60U

International Nuclear Information System (INIS)

Hirohata, Y.; Shibahara, T.; Tanabe, T.; Oya, Y.; Arai, T.; Gotoh, Y.; Masaki, K.; Yagyu, J.; Oyaidzu, M.; Okuno, K.; Nishikawa, M.; Miya, N.

2005-01-01

Retention characteristics of deuterium and hydrogen retained in graphite tiles placed in the divertor region of JT-60U were investigated by thermal desorption spectroscopy (TDS). The deuterium retained in the near surface of all graphite tiles was mostly replaced by hydrogen due to exposure to hydrogen plasma at the final stage operations, resulting in main deuterium retention in the deeper region. The dominant species desorbed from the divertor tiles were H 2 , HD, D 2 and CH 4 . The smallest retention of hydrogen isotopes (H+D) was observed in the outer divertor tile which was eroded with maximum of 20 μm depth. The amount of H+D retained in the inner divertor tiles covered by the re-deposited layers increased with the thickness of the re-deposited layers. Hydrogen isotopes concentration ((H+D)/C) in the re-deposited layers was ∼0.02, which was much smaller than those observed in JET and other devices

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

Retention model for sorptive extraction-thermal desorption of aqueous samples : application to the automated analysis of pesticides and polyaromatic hydrocarbons in water samples

NARCIS (Netherlands)

Baltussen, H.A.; David, F.; Sandra, P.J.F.; Janssen, J.G.M.; Cramers, C.A.M.G.

1998-01-01

In this report, an automated method for sorptive enrichment of aqueous samples is presented. It is based on sorption of the analytes of interest into a packed bed containing 100% polydimethylsiloxane (PDMS) particles followed by thermal desorption for complete transfer of the enriched solutes onto

Defects and morphological changes in nanothin Cu films on polycrystalline Mo analyzed by thermal helium desorption spectrometry

International Nuclear Information System (INIS)

Venugopal, V.; Seijbel, L.J.; Thijsse, B.J.

2005-01-01

Thermal helium desorption spectrometry (THDS) has been used for the investigation of defects and thermal stability of thin Cu films (5-200 A ) deposited on a polycrystalline Mo substrate in ultrahigh vacuum. These films are metastable at room temperature. On heating, the films transform into islands, giving rise to a relatively broad peak in the helium desorption spectra. The temperature of this island formation is dependent on film thickness, being 417 K for 10 A and 1100 K for a 200 A film. The activation energy for island formation was found to be 0.3±0.1 eV for 75 A film. Grain boundaries have a strong effect on island formation. The defect concentration in the as-deposited films is ∼5x10 -4 , for films thicker than 50 A and more for thinner films. Helium release from monovacancies was identified in the case of a 200 A film. Helium release was also seen during sublimation of the Cu film (∼1350 K). Overlayer experiments were used to identify helium trapped close to the film surface. An increase of the substrate temperature during deposition resulted in a film that had already formed islands. Argon-ion assistance (250 eV) during film deposition with an ion/atom ratio of ∼0.1 resulted in a significant enhancement of helium trapping in the films. The argon concentration in the films was found to be 10 -3 . The temperature of island formation was increased due to argon-ion assistance. The helium and argon desorption spectra are found to be similar, which is due to most of the helium becoming trapped in the defects created by the argon beam. The role of the Mo surface in affecting the defects at the film-substrate interface is investigated. The effect of variation of helium fluence and helium implantation energy is also considered. The present THDS results of Cu/poly-Mo are compared to those of Cu/Mo(100) and Cu/Mo(100) reported earlier

Methanol ice co-desorption as a mechanism to explain cold methanol in the gas-phase

Science.gov (United States)

Ligterink, N. F. W.; Walsh, C.; Bhuin, R. G.; Vissapragada, S.; van Scheltinga, J. Terwisscha; Linnartz, H.

2018-05-01

Context. Methanol is formed via surface reactions on icy dust grains. Methanol is also detected in the gas-phase at temperatures below its thermal desorption temperature and at levels higher than can be explained by pure gas-phase chemistry. The process that controls the transition from solid state to gas-phase methanol in cold environments is not understood. Aims: The goal of this work is to investigate whether thermal CO desorption provides an indirect pathway for methanol to co-desorb at low temperatures. Methods: Mixed CH3OH:CO/CH4 ices were heated under ultra-high vacuum conditions and ice contents are traced using RAIRS (reflection absorption IR spectroscopy), while desorbing species were detected mass spectrometrically. An updated gas-grain chemical network was used to test the impact of the results of these experiments. The physical model used is applicable for TW Hya, a protoplanetary disk in which cold gas-phase methanol has recently been detected. Results: Methanol release together with thermal CO desorption is found to be an ineffective process in the experiments, resulting in an upper limit of ≤ 7.3 × 10-7 CH3OH molecules per CO molecule over all ice mixtures considered. Chemical modelling based on the upper limits shows that co-desorption rates as low as 10-6 CH3OH molecules per CO molecule are high enough to release substantial amounts of methanol to the gas-phase at and around the location of the CO thermal desorption front in a protoplanetary disk. The impact of thermal co-desorption of CH3OH with CO as a grain-gas bridge mechanism is compared with that of UV induced photodesorption and chemisorption.

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.

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

Thermal post-deposition treatment effects on nanocrystalline hydrogenated silicon prepared by PECVD under different hydrogen flow rates

Energy Technology Data Exchange (ETDEWEB)

Amor, Sana Ben, E-mail: sana.benamor1@gmail.com [Photovoltaic Laboratory Research and Technology Centre of Energy, Borj-Cedria Science and Technology Park, BP 95, 2050 Hammam-Lif (Tunisia); University of Applied Medical Sciences of Hafr El Baten (Saudi Arabia); Meddeb, Hosny; Daik, Ridha; Othman, Afef Ben; Slama, Sonia Ben; Dimassi, Wissem; Ezzaouia, Hatem [Photovoltaic Laboratory Research and Technology Centre of Energy, Borj-Cedria Science and Technology Park, BP 95, 2050 Hammam-Lif (Tunisia)

2016-01-01

Graphical abstract: At high annealing temperatures, many atoms do not suffer the attraction of surface species due to the thermal agitation and consequently few atoms are adsorbed. As the temperature is lowered the adsorption is more efficient to the point that is no more atoms in the gas phase. Indeed at relatively low temperatures, the atoms have too little energy to escape from the surface or even to vibrate against it. They lost their degree of freedom in the direction perpendicular to the surface. But this does not prevent the atoms to diffuse along the surface. As a result, the layer's thickness decrease with increasing the annealing temperature. - Highlights: The results extracted from this work are: • The post-deposition thermal treatment improves the crystallinity the film at moderate temperature (500 °C). • The higher annealing temperature can lead to decrease the silicon–hydrogen bonds and increase the Si–Si bonds. • Moderate annealing temperature (700 °C) seems to be crucial for obtaining high minority carrier life times. • Hydrogen effusion phenomenon start occurring at 500–550 °C and get worsen at 900 °C. - Abstract: In this paper, hydrogenated nanocrystalline silicon (nc-Si:H) thin films were deposited on mono-crystalline silicon substrate by plasma enhanced chemical vapor deposition (PECVD) under different hydrogen flow rates followed by a thermal treatment in an infrared furnace at different temperature ranging from 300 to 900 °C. The investigated structural, morphological and optoelectronic properties of samples were found to be strongly dependent on the annealing temperature. Raman spectroscopy revealed that nc-Si:H films contain crystalline, amorphous and mixed structures as well. We find that post-deposition thermal treatment may lead to a tendency for structural improvement and a decrease of the disorder in the film network at moderate temperature under 500 °C. As for annealing at higher temperature up to 900 �

Non-thermal production of pure hydrogen from biomass : HYVOLUTION

NARCIS (Netherlands)

Claassen, P.A.M.; Vrije, de G.J.

2006-01-01

HYVOLUTION is the acronym of an Integrated Project ¿Non-thermal production of pure hydrogen from biomass¿ which has been granted in the Sixth EU Framework Programme on Research, Technological Development and Demonstration, Priority 6.1.ii, Sustainable Energy Systems. The aim of HYVOLUTION:

Concept study of a hydrogen containment process during nuclear thermal engine ground testing

OpenAIRE

Wang, Ten-See; Stewart, Eric T.; Canabal, Francisco

2016-01-01

A new hydrogen containment process was proposed for ground testing of a nuclear thermal engine. It utilizes two thermophysical steps to contain the hydrogen exhaust. First, the decomposition of hydrogen through oxygen-rich combustion at higher temperature; second, the recombination of remaining hydrogen with radicals at low temperature. This is achieved with two unit operations: an oxygen-rich burner and a tubular heat exchanger. A computational fluid dynamics methodology was used to analyze ...

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

Microstructural Effects on Hydrogen Delayed Fracture of 600 MPa and 800 MPa grade Deposited Weld Metal

International Nuclear Information System (INIS)

Kang, Hee Jae; Lee, Tae Woo; Cho, Kyung Mox; Kang, Namhyun; Yoon, Byung Hyun; Park, Seo Jeong; Chang, Woong Seong

2012-01-01

Hydrogen-delayed fracture (HDF) was analyzed from the deposited weld metals of 600-MPa and 800-MPa flux-cored arc (FCA) welding wires, and then from the diffusible hydrogen behavior of the weld zone. Two types of deposited weld metal, that is, rutile weld metal and alkali weld metal, were used for each strength level. Constant loading test (CLT) and thermal desorption spectrometry (TDS) analysis were conducted on the hydrogen pre-charged specimens electrochemically for 72 h. The effects of microstructures such as acicular ferrite, grain-boundary ferrite, and low-temperature-transformation phase on the time-to failure and amount of diffusible hydrogen were analyzed. The fracture time for hydrogen-purged specimens in the constant loading tests decreased as the grain size of acicular ferrite decreased. The major trapping site for diffusible hydrogen was the grain boundary, as determined by calculating the activation energies for hydrogen detrapping. As the strength was increased and alkali weld metal was used, the resistance to HDF decreased.

Two-dimensional thermal analysis of liquid hydrogen tank insulation

Energy Technology Data Exchange (ETDEWEB)

Babac, Gulru; Sisman, Altug [Istanbul Technical University, Energy Institute, Ayazaga campus, 34469 Maslak, Istanbul (Turkey); Cimen, Tolga [Jaguar and Landrover, Banbury Road, Gaydon, Warwick CV35 0RR (United Kingdom)

2009-08-15

Liquid hydrogen (LH{sub 2}) storage has the advantage of high volumetric energy density, while boil-off losses constitute a major disadvantage. To minimize the losses, complicated insulation techniques are necessary. In general, Multi Layer Insulation (MLI) and a Vapor-Cooled Shield (VCS) are used together in LH{sub 2} tanks. In the design of an LH{sub 2} tank with VCS, the main goal is to find the optimum location for the VCS in order to minimize heat leakage. In this study, a 2D thermal model is developed by considering the temperature dependencies of the thermal conductivity and heat capacity of hydrogen gas. The developed model is used to analyze the effects of model considerations on heat leakage predictions. Furthermore, heat leakage in insulation of LH{sub 2} tanks with single and double VCS is analyzed for an automobile application, and the optimum locations of the VCS for minimization of heat leakage are determined for both cases. (author)

Adsorption, desorption, and film formation of quinacridone and its thermal cracking product indigo on clean and carbon-covered silicon dioxide surfaces

Energy Technology Data Exchange (ETDEWEB)

Scherwitzl, Boris; Lassnig, Roman; Truger, Magdalena; Resel, Roland; Leising, Günther; Winkler, Adolf, E-mail: a.winkler@tugraz.at [Institute of Solid State Physics, Graz University of Technology, Petersgasse 16, A-8010 Graz (Austria)

2016-09-07

The evaporation of quinacridone from a stainless steel Knudsen cell leads to the partial decomposition of this molecule in the cell, due to its comparably high sublimation temperature. At least one additional type of molecules, namely indigo, could be detected in the effusion flux. Thermal desorption spectroscopy and atomic force microscopy have been used to study the co-deposition of these molecules on sputter-cleaned and carbon-covered silicon dioxide surfaces. Desorption of indigo appears at temperatures of about 400 K, while quinacridone desorbs at around 510 K. For quinacridone, a desorption energy of 2.1 eV and a frequency factor for desorption of 1 × 10{sup 19} s{sup −1} were calculated, which in this magnitude is typical for large organic molecules. A fraction of the adsorbed quinacridone molecules (∼5%) decomposes during heating, nearly independent of the adsorbed amount, resulting in a surface composed of small carbon islands. The sticking coefficients of indigo and quinacridone were found to be close to unity on a carbon covered SiO{sub 2} surface but significantly smaller on a sputter-cleaned substrate. The reason for the latter can be attributed to insufficient energy dissipation for unfavorably oriented impinging molecules. However, due to adsorption via a hot-precursor state, the sticking probability is increased on the surface covered with carbon islands, which act as accommodation centers.

Flash-lamp-crystallized polycrystalline silicon films with high hydrogen concentration formed from Cat-CVD a-Si films

International Nuclear Information System (INIS)

Ohdaira, Keisuke; Tomura, Naohito; Ishii, Shohei; Matsumura, Hideki

2011-01-01

We investigate residual forms of hydrogen (H) atoms such as bonding configuration in poly-crystalline silicon (poly-Si) films formed by the flash-lamp-induced crystallization of catalytic chemical vapor deposited (Cat-CVD) a-Si films. Raman spectroscopy reveals that at least part of H atoms in flash-lamp-crystallized (FLC) poly-Si films form Si-H 2 bonds as well as Si-H bonds with Si atoms even using Si-H-rich Cat-CVD a-Si films, which indicates the rearrangement of H atoms during crystallization. The peak desorption temperature during thermal desorption spectroscopy (TDS) is as high as 900 o C, similar to the reported value for bulk poly-Si.

Thermal balance of a four stroke SI engine operating on hydrogen as a supplementary fuel

International Nuclear Information System (INIS)

Yueksel, F.; Ceviz, M.A.

2003-01-01

This paper investigates the effects of adding constant quantity hydrogen to gasoline-air mixture on SI engine thermal balance and performance. A four stroke, four-cylinder SI engine was used for conducting this study. Thermal balance tests were conducted for engine thermal efficiency, heat loss through the exhaust gases, heat loss to the cooling water and unaccounted losses (i.e. heat lost by lubricating oil, radiation), while performance tests were in respect to the brake power, specific fuel consumption and air ratio. Hydrogen supplementations were used with three different and fixed mass flow rates; 0.129, 0.168 and 0.208 kg h -1 at near three-fourth throttle opening position and variable engine speed ranging from 1000 to 4500 rpm. The results showed that supplementation of hydrogen to gasoline decreases the heat loss to cooling water and unaccounted losses, and the heat loss through the exhaust gas is nearly the same with pure gasoline experiments. Additionally, specific fuel consumption decreases, while the engine thermal efficiency and the air ratio increase. Engine performance parameters such as thermal efficiency and specific fuel consumption improved the level of the ratio of hydrogen mass flow rate to that of gasoline up to 5%

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)

Hydrogen isotope distributions and retentions in the inner divertor tile of JT-60U

Energy Technology Data Exchange (ETDEWEB)

Oya, Y. [Radioisotope Center, University of Tokyo, 2-11-16 Yayoi, Bunkyo-ku, Tokyo 113-0032 (Japan)]. E-mail: yoya@ric.u-tokyo.ac.jp; Hirohata, Y. [Graduate School of Engineering, Hokkaido University, Sapporo 060-8628 (Japan); Tanabe, T. [Graduate School of Engineering, Nagoya University, Nagoya 464-8603 (Japan); Shibahara, T. [Graduate School of Engineering, Nagoya University, Nagoya 464-8603 (Japan); Kimura, H. [Faculty of Science, Shizuoka University, Shizuoka 422-8529 (Japan); Oyaidzu, M. [Faculty of Science, Shizuoka University, Shizuoka 422-8529 (Japan); Arai, T. [Naka Fusion Establishment, Japan Atomic Energy Research Institute, Naka-machi, Naka-gun, Ibaraki 311-0193 (Japan); Masaki, K. [Naka Fusion Establishment, Japan Atomic Energy Research Institute, Naka-machi, Naka-gun, Ibaraki 311-0193 (Japan); Gotoh, Y. [Naka Fusion Establishment, Japan Atomic Energy Research Institute, Naka-machi, Naka-gun, Ibaraki 311-0193 (Japan); Okuno, K. [Faculty of Science, Shizuoka University, Shizuoka 422-8529 (Japan); Miya, N. [Naka Fusion Establishment, Japan Atomic Energy Research Institute, Naka-machi, Naka-gun, Ibaraki 311-0193 (Japan); Hino, T. [Graduate School of Engineering, Hokkaido University, Sapporo 060-8628 (Japan); Tanaka, S. [Graduate School of Engineering, University of Tokyo, Tokyo 113-8656 (Japan)

2005-11-15

Retention profiles of hydrogen and deuterium in graphite tiles placed in the inner divertor region of JT-60U were analyzed by secondary ion mass spectroscopy (SIMS) and thermal desorption spectroscopy (TDS). The difference in hydrogen and deuterium retention behaviour is discussed considering the frequency of the strike-point hit and history of NBI heating power. It was found that most of hydrogen/deuterium was retained in the deposited layers, HH deposition layers/DD deposition layers or co-deposited with carbon. Owing to the higher heating power of DD discharges, the deuterium concentration in the DD deposition layers was much lower than that of hydrogen in the HH deposition layers. On the area showing no deposition, very shallow profile of deuterium dominated hydrogen profile. These results indicate that the tritium retention is strongly influenced by the history of discharge and temperatures. Tritium retention on graphite tiles and deposition layers could be significantly reduced with increasing the operation temperature.

Hydrogen isotope distributions and retentions in the inner divertor tile of JT-60U

International Nuclear Information System (INIS)

Oya, Y.; Hirohata, Y.; Tanabe, T.; Shibahara, T.; Kimura, H.; Oyaidzu, M.; Arai, T.; Masaki, K.; Gotoh, Y.; Okuno, K.; Miya, N.; Hino, T.; Tanaka, S.

2005-01-01

Retention profiles of hydrogen and deuterium in graphite tiles placed in the inner divertor region of JT-60U were analyzed by secondary ion mass spectroscopy (SIMS) and thermal desorption spectroscopy (TDS). The difference in hydrogen and deuterium retention behaviour is discussed considering the frequency of the strike-point hit and history of NBI heating power. It was found that most of hydrogen/deuterium was retained in the deposited layers, HH deposition layers/DD deposition layers or co-deposited with carbon. Owing to the higher heating power of DD discharges, the deuterium concentration in the DD deposition layers was much lower than that of hydrogen in the HH deposition layers. On the area showing no deposition, very shallow profile of deuterium dominated hydrogen profile. These results indicate that the tritium retention is strongly influenced by the history of discharge and temperatures. Tritium retention on graphite tiles and deposition layers could be significantly reduced with increasing the operation temperature

Application of Thermal Desorption Unit (TDU) to treat low-toxicity mineral oil base cuttings in Barinas District, Venezuela

Energy Technology Data Exchange (ETDEWEB)

Rendon, Ruben [Petroleos de Venezuela, Caracas (Venezuela); Luzardo, Janeth; Alcoba, Alcides [M-I SWACO, Houston, TX (United States)

2008-07-01

The potential environmental impact of oil-based drill cuttings is generating increased scrutiny in the oil and gas industry. If left untreated, oil-based cuttings not only increase the risk of environmental liabilities, but also affect revenue, as drilling generates wastes that in most cases require special treatment before disposal. Consequently, the oil industry is looking for technologies to help minimize environmental liabilities. Accordingly, the Barinas District of PDVSA has started a pilot trial to treat oil-based drilling cuttings by applying thermal desorption technology. The main objective of this technology is recovering trapped hydrocarbons, while minimizing wastes and preparing solids to be disposed of through a mobile treatment plant. This novel technology has been used worldwide to treat organic pollutants in soil. Thermal desorption is a technology based on the application of heat in soils polluted with organic compounds. With this technology, target temperatures vary according to the type and concentration of detected pollutants along with its characterization, in such a way that compounds are disposed of by volatilization. As part of the integral waste management development along with the pilot trial for hydrocarbon-contaminated solid waste treatment, trials on soils were undertaken by applying process-generated ashes in equally-sized bins, with different mixtures (ashes, ashes organic material, ashes-organic material-sand, ashes-land). The resulting process offers an immediate soil remediation and final disposal solution for toxic and dangerous waste. (author)

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)

Evaluation of contaminated soil remediation by low temperature thermal desorption

International Nuclear Information System (INIS)

Gibbs, L.; Punt, M.

1993-01-01

Soil contaminated with diesel and aviation fuels has been excavated and stored at a Canadian Forces Base in Ontario. Because of the volatile nature of this contamination, it was determined that low temperature thermal desorption (LTTD) would be an effective method of remediating this soil. A full scale evaluation of LTTD technology was conducted at the base to determine its acceptability for other sites. In the LTTD process, soil enters a primary treatment unit and is heated to a sufficiently high temperature to volatilize the hydrocarbon contaminants. Offgases are treated in a secondary combustion chamber. Primary treatment kiln temperature was maintained at 260 degree C for each test during the evaluation. The LTTD unit was evaluated for two sets of operating conditions: two levels of inlet soil total petroleum hydrocarbon concentrations and two feed rates (16,000 and 22,000 kg/h). Emissions from the LTTD unit were monitored continuously for volatile organics, moisture, and gas velocity. Results of the tests and emissions analyses are presented. Outlet soil hydrocarbon concentration requirements of 100 ppM were not exceeded during the evaluation. Air hydrocarbon emissions only exceeded 100-ppM limits under upset conditions, otherwise virturally no total hydrocarbon content was observed in the stack gas. 5 refs., 6 figs., 9 tabs

Thermal neutron pulsed parameters in non-hydrogenous systems. Experiment for lead grains

International Nuclear Information System (INIS)

Drozdowicz, K.; Gabanska, B.; Kosik, M.; Krynicka, E.; Woznicka, U.; Zaleski, T.

1997-01-01

In Czubek's method of measurement of the thermal neutron macroscopic absorption cross section a two-region geometry is applied where the investigated sample is surrounded by an external moderator. Both regions in the measurements made up till now were hydrogenous, which means the same type of the thermal neutron transport properties. In the paper a theoretical consideration to use non-hydrogenous materials as the samples is presented. Pulsed neutron measurements have been performed on homogeneous material in a geometry of the classic experiment with the variable geometric buckling. Two decay constants have been measured for different cylindrical samples of small lead grains (a lead shot). (author)

Hydrogen storage by physisorption on porous materials

Energy Technology Data Exchange (ETDEWEB)

Panella, B

2006-09-13

A great challenge for commercializing hydrogen powered vehicles is on-board hydrogen storage using economic and secure systems. A possible solution is hydrogen storage in light-weight solid materials. Here three principle storage mechanisms can be distinguished: i) absorption of hydrogen in metals ii) formation of compounds with ionic character, like complex hydrides and iii) physisorption (or physical adsorption) of hydrogen molecules on porous materials. Physical adsorption exhibits several advantages over chemical hydrogen storage as for example the complete reversibility and the fast kinetics. Two classes of porous materials were investigated for physical hydrogen storage, i.e. different carbon nanostructures and crystalline metal-organic frameworks possessing extremely high specific surface area. Hydrogen adsorption isotherms were measured using a Sieverts' apparatus both at room temperature and at 77 K at pressures up to the saturation regime. Additionally, the adsorption sites of hydrogen in these porous materials were identified using thermal desorption spectroscopy extended to very low temperatures (down to 20 K). Furthermore, the adsorbed hydrogen phase was studied in various materials using Raman spectroscopy at different pressures and temperatures. The results show that the maximum hydrogen storage capacity of porous materials correlates linearly with the specific surface area and is independent of structure and composition. In addition the pore structure of the adsorbent plays an important role for hydrogen storage since the adsorption sites for H2 could be assigned to pores possessing different dimensions. Accordingly it was shown that small pores are necessary to reach high storage capacities already at low pressures. This new understanding may help to tailor and optimize new porous materials for hydrogen storage. (orig.)

Hydrogen storage by physisorption on porous materials

Energy Technology Data Exchange (ETDEWEB)

Panella, B.

2006-09-13

A great challenge for commercializing hydrogen powered vehicles is on-board hydrogen storage using economic and secure systems. A possible solution is hydrogen storage in light-weight solid materials. Here three principle storage mechanisms can be distinguished: i) absorption of hydrogen in metals ii) formation of compounds with ionic character, like complex hydrides and iii) physisorption (or physical adsorption) of hydrogen molecules on porous materials. Physical adsorption exhibits several advantages over chemical hydrogen storage as for example the complete reversibility and the fast kinetics. Two classes of porous materials were investigated for physical hydrogen storage, i.e. different carbon nanostructures and crystalline metal-organic frameworks possessing extremely high specific surface area. Hydrogen adsorption isotherms were measured using a Sieverts' apparatus both at room temperature and at 77 K at pressures up to the saturation regime. Additionally, the adsorption sites of hydrogen in these porous materials were identified using thermal desorption spectroscopy extended to very low temperatures (down to 20 K). Furthermore, the adsorbed hydrogen phase was studied in various materials using Raman spectroscopy at different pressures and temperatures. The results show that the maximum hydrogen storage capacity of porous materials correlates linearly with the specific surface area and is independent of structure and composition. In addition the pore structure of the adsorbent plays an important role for hydrogen storage since the adsorption sites for H2 could be assigned to pores possessing different dimensions. Accordingly it was shown that small pores are necessary to reach high storage capacities already at low pressures. This new understanding may help to tailor and optimize new porous materials for hydrogen storage. (orig.)

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.

Thermal decay of rhodopsin: role of hydrogen bonds in thermal isomerization of 11-cis retinal in the binding site and hydrolysis of protonated Schiff base.

Science.gov (United States)

Liu, Jian; Liu, Monica Yun; Nguyen, Jennifer B; Bhagat, Aditi; Mooney, Victoria; Yan, Elsa C Y

2009-07-01

Although thermal stability of the G protein-coupled receptor rhodopsin is directly related to its extremely low dark noise level and has recently generated considerable interest, the chemistry behind the thermal decay process of rhodopsin has remained unclear. Using UV-vis spectroscopy and HPLC analysis, we have demonstrated that the thermal decay of rhodopsin involves both hydrolysis of the protonated Schiff base and thermal isomerization of 11-cis to all-trans retinal. Examining the unfolding of rhodopsin by circular dichroism spectroscopy and measuring the rate of thermal isomerization of 11-cis retinal in solution, we conclude that the observed thermal isomerization of 11-cis to all-trans retinal happens when 11-cis retinal is in the binding pocket of rhodopsin. Furthermore, we demonstrate that solvent deuterium isotope effects are involved in the thermal decay process by decreasing the rates of thermal isomerization and hydrolysis, suggesting that the rate-determining step of these processes involves breaking hydrogen bonds. These results provide insight into understanding the critical role of an extensive hydrogen-bonding network on stabilizing the inactive state of rhodopsin and contribute to our current understanding of the low dark noise level of rhodopsin, which enables this specialized protein to function as an extremely sensitive biological light detector. Because similar hydrogen-bonding networks have also been suggested by structural analysis of two other GPCRs, beta1 and beta2 adrenergic receptors, our results could reveal a general role of hydrogen bonds in facilitating GPCR function.

Sustainable remediation of mercury contaminated soils by thermal desorption.

Science.gov (United States)

Sierra, María J; Millán, Rocio; López, Félix A; Alguacil, Francisco J; Cañadas, Inmaculada

2016-03-01

Mercury soil contamination is an important environmental problem that needs the development of sustainable and efficient decontamination strategies. This work is focused on the application of a remediation technique that maintains soil ecological and environmental services to the extent possible as well as search for alternative sustainable land uses. Controlled thermal desorption using a solar furnace at pilot scale was applied to different types of soils, stablishing the temperature necessary to assure the functionality of these soils and avoid the Hg exchange to the other environmental compartments. Soil mercury content evolution (total, soluble, and exchangeable) as temperature increases and induced changes in selected soil quality indicators are studied and assessed. On total Hg, the temperature at which it is reduced until acceptable levels depends on the intended soil use and on how restrictive are the regulations. For commercial, residential, or industrial uses, soil samples should be heated to temperatures higher than 280 °C, at which more than 80 % of the total Hg is released, reaching the established legal total Hg level and avoiding eventual risks derived from high available Hg concentrations. For agricultural use or soil natural preservation, conversely, maintenance of acceptable levels of soil quality limit heating temperatures, and additional treatments must be considered to reduce available Hg. Besides total Hg concentration in soils, available Hg should be considered to make final decisions on remediation treatments and potential future uses. Graphical Abstract Solar energy use for remediation of soils affected by mercury.

Characterization of olive oil volatiles by multi-step direct thermal desorption-comprehensive gas chromatography-time-of-flight mass spectrometry using a programmed temperature vaporizing injector

NARCIS (Netherlands)

de Koning, S.; Kaal, E.; Janssen, H.-G.; van Platerink, C.; Brinkman, U.A.Th.

2008-01-01

The feasibility of a versatile system for multi-step direct thermal desorption (DTD) coupled to comprehensive gas chromatography (GC × GC) with time-of-flight mass spectrometric (TOF-MS) detection is studied. As an application the system is used for the characterization of fresh versus aged olive

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.)

Concept study of a hydrogen containment process during nuclear thermal engine ground testing

Science.gov (United States)

Wang, Ten-See; Stewart, Eric T.; Canabal, Francisco

A new hydrogen containment process was proposed for ground testing of a nuclear thermal engine. It utilizes two thermophysical steps to contain the hydrogen exhaust. First, the decomposition of hydrogen through oxygen-rich combustion at higher temperature; second, the recombination of remaining hydrogen with radicals at low temperature. This is achieved with two unit operations: an oxygen-rich burner and a tubular heat exchanger. A computational fluid dynamics methodology was used to analyze the entire process on a three-dimensional domain. The computed flammability at the exit of the heat exchanger was less than the lower flammability limit, confirming the hydrogen containment capability of the proposed process.

Ocean thermal plantships for production of ammonia as the hydrogen carrier.

Energy Technology Data Exchange (ETDEWEB)

Panchal, C.B.; Pandolfini, P. P.; Kumm, W. H.; Energy Systems; Johns Hopkins Univ.; Arctic Energies, Ltd.

2009-12-02

Conventional petroleum, natural gas, and coal are the primary sources of energy that have underpinned modern civilization. Their continued availability in the projected quantities required and the impacts of emission of greenhouse gases (GHGs) on the environment are issues at the forefront of world concerns. New primary sources of energy are being sought that would significantly reduce the emissions of GHGs. One such primary source that can help supply energy, water, and fertilizer without GHG emissions is available in the heretofore unexploited thermal gradients of the tropical oceans. The world's oceans are the largest natural collector and reservoir of solar energy. The potential of ocean energy is limitless for producing base-load electric power or ammonia as the hydrogen carrier and fresh water from seawater. However, until now, ocean energy has been virtually untapped. The general perception is that ocean thermal energy is limited to tropical countries. Therefore, the full potential of at-sea production of (1) ammonia as a hydrogen carrier and (2) desalinated water has not been adequately evaluated. Using ocean thermal plantships for the at-sea co-production of ammonia as a hydrogen carrier and desalinated water offer potential energy, environmental, and economic benefits that support the development of the technology. The introduction of a new widespread solution to our projected energy supply requires lead times of a decade or more. Although continuation of the ocean thermal program from the 1970s would likely have put us in a mitigating position in the early 2000s, we still have a window of opportunity to dedicate some of our conventional energy sources to the development of this renewable energy by the time new sources would be critically needed. The primary objective of this project is to evaluate the technical and economic viability of ocean thermal plantships for the production of ammonia as the hydrogen carrier. This objective is achieved by

A Solid Trap and Thermal Desorption System with Application to a Medical Electronic Nose

Directory of Open Access Journals (Sweden)

Xuntao Xu

2008-11-01

Full Text Available In this paper, a solid trap/thermal desorption-based odorant gas condensation system has been designed and implemented for measuring low concentration odorant gas. The technique was successfully applied to a medical electronic nose system. The developed system consists of a flow control unit, a temperature control unit and a sorbent tube. The theoretical analysis and experimental results indicate that gas condensation, together with the medical electronic nose system can significantly reduce the detection limit of the nose system and increase the system’s ability to distinguish low concentration gas samples. In addition, the integrated system can remove the influence of background components and fluctuation of operational environment. Even with strong disturbances such as water vapour and ethanol gas, the developed system can classify the test samples accurately.

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)

Effects of alloying elements on thermal desorption of helium in Ni alloys

International Nuclear Information System (INIS)

Xu, Q.; Cao, X.Z.; Sato, K.; Yoshiie, T.

2012-01-01

It is well known that the minor elements Si and Sn can suppress the formation of voids in Ni alloys. In the present study, to investigate the effects of Si and Sn on the retention of helium in Ni alloys, Ni, Ni–Si, and Ni–Sn alloys were irradiated by 5 keV He ions at 723 K. Thermal desorption spectroscopy (TDS) was performed at up to 1520 K, and microstructural observations were carried out to identify the helium trapping sites during the TDS analysis. Two peaks, at 1350 and 1457 K, appeared in the TDS spectrum of Ni. On the basis of the microstructural observations, the former peak was attributed to the release of trapped helium from small cavities and the latter to its release from large cavities. Small-cavity helium trapping sites were also found in the Ni–Si and Ni–Sn alloys, but no large cavities were observed in these alloys. In addition, it was found that the oversized element Sn could trap He atoms in the Ni–Sn alloy.

Effects of alloying elements on thermal desorption of helium in Ni alloys

Energy Technology Data Exchange (ETDEWEB)

Xu, Q., E-mail: xu@rri.kyoto-u.ac.jp [Research Reactor Institute, Kyoto University, Osaka 590-0494 (Japan); Cao, X.Z.; Sato, K.; Yoshiie, T. [Research Reactor Institute, Kyoto University, Osaka 590-0494 (Japan)

2012-12-15

It is well known that the minor elements Si and Sn can suppress the formation of voids in Ni alloys. In the present study, to investigate the effects of Si and Sn on the retention of helium in Ni alloys, Ni, Ni-Si, and Ni-Sn alloys were irradiated by 5 keV He ions at 723 K. Thermal desorption spectroscopy (TDS) was performed at up to 1520 K, and microstructural observations were carried out to identify the helium trapping sites during the TDS analysis. Two peaks, at 1350 and 1457 K, appeared in the TDS spectrum of Ni. On the basis of the microstructural observations, the former peak was attributed to the release of trapped helium from small cavities and the latter to its release from large cavities. Small-cavity helium trapping sites were also found in the Ni-Si and Ni-Sn alloys, but no large cavities were observed in these alloys. In addition, it was found that the oversized element Sn could trap He atoms in the Ni-Sn alloy.

Effects of alloying elements on thermal desorption of helium in Ni alloys

Science.gov (United States)

Xu, Q.; Cao, X. Z.; Sato, K.; Yoshiie, T.

2012-12-01

It is well known that the minor elements Si and Sn can suppress the formation of voids in Ni alloys. In the present study, to investigate the effects of Si and Sn on the retention of helium in Ni alloys, Ni, Ni-Si, and Ni-Sn alloys were irradiated by 5 keV He ions at 723 K. Thermal desorption spectroscopy (TDS) was performed at up to 1520 K, and microstructural observations were carried out to identify the helium trapping sites during the TDS analysis. Two peaks, at 1350 and 1457 K, appeared in the TDS spectrum of Ni. On the basis of the microstructural observations, the former peak was attributed to the release of trapped helium from small cavities and the latter to its release from large cavities. Small-cavity helium trapping sites were also found in the Ni-Si and Ni-Sn alloys, but no large cavities were observed in these alloys. In addition, it was found that the oversized element Sn could trap He atoms in the Ni-Sn alloy.

Microwave-Enhanced Thermal Desorption of Polyhalogenated Biphenyls from Contaminated Soil

Czech Academy of Sciences Publication Activity Database

Kaštánek, P.; Kaštánek, František; Hájek, Milan

2010-01-01

Roč. 136, č. 3 (2010), s. 295-300 ISSN 0733-9372 Institutional research plan: CEZ:AV0Z40720504 Keywords : microwave * experiments * desorption Subject RIV: CI - Industrial Chemistry, Chemical Engineering Impact factor: 1.117, year: 2010

Effects of hydrogen mixture into helium gas on deuterium removal from lithium titanate

Energy Technology Data Exchange (ETDEWEB)

Tsuchiya, Akihito, E-mail: tsuchiya@frontier.hokudai.ac.jp [Laboratory of Plasma Physics and Engineering, Hokkaido University, Kita-13, Nishi-8, Kita-ku, Sapporo 060-8628 (Japan); Hino, Tomoaki; Yamauchi, Yuji; Nobuta, Yuji [Laboratory of Plasma Physics and Engineering, Hokkaido University, Kita-13, Nishi-8, Kita-ku, Sapporo 060-8628 (Japan); Akiba, Masato; Enoeda, Mikio [Japan Atomic Energy Agency, 801-1, Mukoyama, Naka 311-0193 (Japan)

2013-10-15

Lithium titanate (Li{sub 2}TiO{sub 3}) pebbles were irradiated with deuterium ions with energy of 1.7 keV and then exposed to helium or helium–hydrogen mixed gas at various temperatures, in order to evaluate the effects of gas exposure on deuterium removal from the pebbles. The amounts of residual deuterium in the pebbles were measured by thermal desorption spectroscopy. The mixing of hydrogen gas into helium gas enhanced the removal amount of deuterium. In other words, the amount of residual deuterium after the helium–hydrogen mixed gas exposure at lower temperature was lower than that after the helium gas exposure. In addition, we also evaluated the pebbles exposed to the helium gas with different hydrogen mixture ratio from 0% to 1%, at 573 K. Although the amount of residual deuterium in the pebbles after the exposure decreased with increasing the hydrogen mixture ratio, the implanted deuterium partly remained after the exposure. These results suggest that the tritium inventory may occur at low temperature region in the blanket during the operation.

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...

Significance of Isotopically Labile Organic Hydrogen in Thermal Maturation of Organic Matter

Energy Technology Data Exchange (ETDEWEB)

Arndt Schimmelmann; Maria Mastalerz

2010-03-30

Isotopically labile organic hydrogen in fossil fuels occupies chemical positions that participate in isotopic exchange and in chemical reactions during thermal maturation from kerogen to bitumen, oil and gas. Carbon-bound organic hydrogen is isotopically far less exchangeable than hydrogen bound to nitrogen, oxygen, or sulfur. We explore why organic hydrogen isotope ratios express a relationship with organic nitrogen isotope ratios in kerogen at low to moderate maturity. We develop and apply new techniques to utilize organic D/H ratios in organic matter fractions and on a molecular level as tools for exploration for fossil fuels and for paleoenvironmental research. The scope of our samples includes naturally and artificially matured substrates, such as coal, shale, oil and gas.

Advanced materials for solid state hydrogen storage: “Thermal engineering issues”

International Nuclear Information System (INIS)

Srinivasa Murthy, S.; Anil Kumar, E.

2014-01-01

Hydrogen has been widely recognized as the “Energy Carrier” of the future. Efficient, reliable, economical and safe storage and delivery of hydrogen form important aspects in achieving success of the “Hydrogen Economy”. Gravimetric and volumetric storage capacities become important when one considers portable and mobile applications of hydrogen. In the case of solid state hydrogen storage, the gas is reversibly embedded (by physisorption and/or chemisorption) in a solid matrix. A wide variety of materials such as intermetallics, physisorbents, complex hydrides/alanates, metal organic frameworks, etc. have been investigated as possible storage media. This paper discusses the feasibility of lithium– and sodium–aluminum hydrides with emphasis on their thermodynamic and thermo-physical properties. Drawbacks such as poor heat transfer characteristics and poor kinetics demand special attention to the thermal design of solid state storage devices. - Highlights: • Advanced materials suitable for solid state hydrogen storage are discussed. • Issues related to thermodynamic and thermo-physical properties of hydriding materials are brought out. • Hydriding and dehydriding behavior including sorption kinetics of complex hydrides with emphasis on alanates are explained

Targets for bulk hydrogen analysis using thermal neutrons

CERN Document Server

Csikai, J; Buczko, C M

2002-01-01

The reflection property of substances can be characterized by the reflection cross-section of thermal neutrons, sigma subbeta. A combination of the targets with thin polyethylene foils allowed an estimation of the flux depression of thermal neutrons caused by a bulk sample containing highly absorbing elements or compounds. Some new and more accurate sigma subbeta values were determined by using the combined target arrangement. For the ratio, R of the reflection and the elastic scattering cross-sections of thermal neutrons, R=sigma subbeta/sigma sub E sub L a value of 0.60+-0.02 was found on the basis of the data obtained for a number of elements from H to Pb. Using this correlation factor, and the sigma sub E sub L values, the unknown sigma subbeta data can be deduced. The equivalent thicknesses, to polyethylene or hydrogen, of the different target materials were determined from the sigma subbeta values.

Thermal shock testing of TiC-coated molybdenum with pulsed hydrogen beams

International Nuclear Information System (INIS)

Nakamura, Kazuyuki

1985-07-01

Thermal shock testing of molybdenum samples, on which TiC is coated by TP-CVD and CVD methods, has been made by using a pulsed hydrogen beam. The power density applied was 2 kw/cm 2 . The test results showed that TiC coatings did not exfoliate until the melting of the substrate and showed good adhesion under the thermal shock condition. (author)

Novel Auto thermal Reforming Process for Pure Hydrogen Production

International Nuclear Information System (INIS)

Chen, Z.; Elnashaie, S.S.E.H.

2004-01-01

Steam reforming of heptane for hydrogen production is investigated in a novel Circulating Fluidized Bed Membrane Reformer-Regenerator system (CFBMRR) utilizing a number of hydrogen and oxygen selective membranes. It is shown that although the amount of carbon deposition is significant, the effect on catalyst deactivation is negligible due to the large solid to gas mass feed ratio and the continuous catalyst regeneration in the system. The combustion of the deposited carbon in the catalyst regenerator supplies the heat needed for the endothermic steam reforming as well as the combustion of flammable gases from the riser reformer. Auto thermal operation is achievable for the entire adiabatic reformer-regenerator system when the exothermic heat generated from the regenerator is sufficient to compensate the endothermic heat consumed in the reformer. Multiplicity of the steady states exists in the range of steam to carbon feed ratio of 1.4442.251 mol/mol. The novel configuration has the potential advantages not only with respect to hydrogen production but also energy minimization

Experimental data of thermal cracking of soybean oil and blends with hydrogenated fat

Directory of Open Access Journals (Sweden)

R.F. Beims

2018-04-01

Full Text Available This article presents the experimental data on the thermal cracking of soybean oil and blends with hydrogenated fat. Thermal cracking experiments were carried out in a plug flow reactor with pure soybean oil and two blends with hydrogenated fat to reduce the degree of unsaturation of the feedstock. The same operational conditions was considered. The data obtained showed a total aromatics content reduction by 14% with the lowest degree of unsaturation feedstock. Other physicochemical data is presented, such as iodine index, acid index, density, kinematic viscosity. A distillation curve was carried out and compared with the curve from a petroleum sample.

Peak pressures from hydrogen deflagrations in the PFP thermal stabilization glovebox

International Nuclear Information System (INIS)

Van Keuren, J.C.

1998-01-01

This document describes the calculations of the peak pressures due to hydrogen deflagrations in the glovebox used for thermal stabilization (glovebox HC-21A) in PFP. Two calculations were performed. The first considered the burning of hydrogen released from a 7 inch Pu can in the Inert Atmosphere Confinement (IAC) section of the glovebox. The peak pressure increase was 12400 Pa (1.8 psi). The second calculation considered burning of the hydrogen from 25 g of plutonium hydride in the airlock leading to the main portion of the glovebox. Since the glovebox door exposes most of the airlock when open, the deflagration was assumed to pressurize the entire glovebox. The peak pressure increase was 3860 Pa (0.56 psi)

Effectiveness of thermal ignition devices in lean hydrogen-air-steam mixtures

International Nuclear Information System (INIS)

Tamm, H.; McFarlane, R.; Liu, D.D.S.

1985-03-01

Deliberate ignition of hydrogen at low concentrations in reactor containment systems is one method of controlling hydrogen during degraded core accidents. Since many postulated accident conditions have substantial amounts of steam present, experiments have been performed to determine the hydrogen-air-steam concentration regimes in which ignitors would be effective. In these experiments, both a GM AC 7G thermal flow plug and a Tayco Model 3442 ignitor have been used. These ignitors have been installed in PWR containments with ice condensers and in BWR Mark III containments. This report presents the results of these ignitor effectiveness experiments, and gives the ignition limits and the effect of steam on the ignitor surface temperatures required for ignition

Efficient STEP (solar thermal electrochemical photo) production of hydrogen - an economic assessment

Energy Technology Data Exchange (ETDEWEB)

Licht, Stuart [Department of Chemistry, George Washington University, Ashburn, VA 20147 (United States); Solar Institute, George Washington University, Washington, DC 20052 (United States); Chitayat, Olivia; Bergmann, Harry; Dick, Andrew; Ayub, Hina [Solar Institute, George Washington University, Washington, DC 20052 (United States); Ghosh, Susanta [Department of Chemistry, George Washington University, Ashburn, VA 20147 (United States); Department of Chemistry, Visva-Bharati, Santiniketan (India)

2010-10-15

A consideration of the economic viability of hydrogen fuel production is important in the STEP (Solar Thermal Electrochemical Photo) production of hydrogen fuel. STEP is an innovative way to decrease costs and increase the efficiency of hydrogen fuel production, which is a synergistic process that can use concentrating photovoltaics (CPV) and solar thermal energy to drive a high temperature, low voltage, electrolysis (water-splitting), resulting in H{sub 2} at decreased energy and higher solar efficiency. This study provides evidence that the STEP system is an economically viable solution for the production of hydrogen. STEP occurs at both higher electrolysis and solar conversion efficiencies than conventional room temperature photovoltaic (PV) generation of hydrogen. This paper probes the economic viability of this process, by comparing four different systems: (1) 10% or (2) 14% flat plate PV driven aqueous alkaline electrolysis H{sub 2} production, (3) 25% CPV driven molten electrolysis H{sub 2} production, and (4) 35% CPV driven solid oxide electrolysis H{sub 2} production. The molten and solid oxide electrolysers are high temperature systems that can make use of light, normally discarded, for heating. This significantly increases system efficiency. Using levelized cost analysis, this study shows significant cost reduction using the STEP system. The total price per kg of hydrogen is shown to decrease from 5.74 to 4.96 to 3.01 to 2.61 with the four alternative systems. The advanced STEP plant requires less than one seventh of the land area of the 10% flat cell plant. To generate the 216 million kg H{sub 2}/year required by 1 million fuel cell vehicles, the 35% CPV driven solid oxide electrolysis requires a plant only 9.6 mi{sup 2} in area. While PV and electrolysis components dominate the cost of conventional PV generated hydrogen, they do not dominate the cost of the STEP-generated hydrogen. The lower cost of STEP hydrogen is driven by residual distribution and

Defect annealing and thermal desorption of deuterium in low dose HFIR neutron-irradiated tungsten

International Nuclear Information System (INIS)

Shimada, Masashi; Hara, Masanori; Otsuka, Teppei; Oya, Yasuhisa; Hatano, Yuji

2015-01-01

Three tungsten samples irradiated at High Flux Isotope Reactor at Oak Ridge National Laboratory were exposed to deuterium plasma (ion fluence of 1 × 10 26 m −2 ) at three different temperatures (100, 200, and 500 °C) in Tritium Plasma Experiment at Idaho National Laboratory. Subsequently, thermal desorption spectroscopy was performed with a ramp rate of 10 °C min −1 up to 900 °C, and the samples were annealed at 900 °C for 0.5 h. These procedures were repeated three times to uncover defect-annealing effects on deuterium retention. The results show that deuterium retention decreases approximately 70% for at 500 °C after each annealing, and radiation damages were not annealed out completely even after the 3rd annealing. TMAP modeling revealed the trap concentration decreases approximately 80% after each annealing at 900 °C for 0.5 h

Defect annealing and thermal desorption of deuterium in low dose HFIR neutron-irradiated tungsten

Science.gov (United States)

Shimada, Masashi; Hara, Masanori; Otsuka, Teppei; Oya, Yasuhisa; Hatano, Yuji

2015-08-01

Three tungsten samples irradiated at High Flux Isotope Reactor at Oak Ridge National Laboratory were exposed to deuterium plasma (ion fluence of 1 × 1026 m-2) at three different temperatures (100, 200, and 500 °C) in Tritium Plasma Experiment at Idaho National Laboratory. Subsequently, thermal desorption spectroscopy was performed with a ramp rate of 10 °C min-1 up to 900 °C, and the samples were annealed at 900 °C for 0.5 h. These procedures were repeated three times to uncover defect-annealing effects on deuterium retention. The results show that deuterium retention decreases approximately 70% for at 500 °C after each annealing, and radiation damages were not annealed out completely even after the 3rd annealing. TMAP modeling revealed the trap concentration decreases approximately 80% after each annealing at 900 °C for 0.5 h.

Defect annealing and thermal desorption of deuterium in low dose HFIR neutron-irradiated tungsten

Energy Technology Data Exchange (ETDEWEB)

Shimada, Masashi, E-mail: Masashi.Shimada@inl.gov [Fusion Safety Program, Idaho National Laboratory, Idaho Falls, ID (United States); Hara, Masanori [Hydrogen Isotope Research Center, University of Toyama, Toyama (Japan); Otsuka, Teppei [Kyushu University, Interdisciplinary Graduate School of Engineering Science, Higashi-ku, Fukuoka (Japan); Oya, Yasuhisa [Radioscience Research Laboratory, Faculty of Science, Shizuoka University, Shizuoka (Japan); Hatano, Yuji [Hydrogen Isotope Research Center, University of Toyama, Toyama (Japan)

2015-08-15

Three tungsten samples irradiated at High Flux Isotope Reactor at Oak Ridge National Laboratory were exposed to deuterium plasma (ion fluence of 1 × 10{sup 26} m{sup −2}) at three different temperatures (100, 200, and 500 °C) in Tritium Plasma Experiment at Idaho National Laboratory. Subsequently, thermal desorption spectroscopy was performed with a ramp rate of 10 °C min{sup −1} up to 900 °C, and the samples were annealed at 900 °C for 0.5 h. These procedures were repeated three times to uncover defect-annealing effects on deuterium retention. The results show that deuterium retention decreases approximately 70% for at 500 °C after each annealing, and radiation damages were not annealed out completely even after the 3rd annealing. TMAP modeling revealed the trap concentration decreases approximately 80% after each annealing at 900 °C for 0.5 h.

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)

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...

Integrated processing for the treatment of materials applied to thermal compression of hydrogen

International Nuclear Information System (INIS)

Rodriguez, M.G; Esquivel, M. R

2009-01-01

In this work, AB 5 intermetallics are synthesized by low energy mechanical alloying according to: AB 5 + AB 5 = AB 5 . The obtained intermetallics are annealed at 600 oC to optimize both the microstructural and hydrogen sorption properties. Then, the material is applied to the design of schemes for thermal compression of hydrogen (TCH). These results are obtained within the frame of a research project related to Energy and Environment and focused on the replacement on fossil supply systems by a hydrogen based one. [es

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.

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.

Evaluation of hydrogen trapping mechanisms during performance of different hydrogen fugacity in a lean duplex stainless steel

Energy Technology Data Exchange (ETDEWEB)

Silverstein, R., E-mail: barrav@post.bgu.ac.il [Department of Material Science and Engineering, Ben-Gurion University of the Negev, Beer-Sheva (Israel); Eliezer, D. [Department of Material Science and Engineering, Ben-Gurion University of the Negev, Beer-Sheva (Israel); Glam, B.; Eliezer, S.; Moreno, D. [Soreq Nuclear Research Center, Yavne, 81800 (Israel)

2015-11-05

Hydrogen trapping behavior in a lean duplex stainless steel (LDS) is studied by means of thermal desorption spectrometry (TDS). The susceptibility of a metal to hydrogen embrittlement is directly related to the trap characteristics: source or sink (reversible or irreversible, respectively). Since trapping affects the metal's diffusivity, it has a major influence on the hydrogen assisted cracking (HAC) phenomenon. It is known from previously published works that the susceptibility will depend on the competition between reversible and irreversible traps; meaning a direct relation to the hydrogen's initial state in the steel. In this research the trapping mechanism of LDS, exposed to different hydrogen charging environments, is analyzed by means of TDS. The TDS analysis was supported and confirmed by means of X-ray diffraction (XRD), hydrogen quantitative measurements and microstructural observations. It was found that gaseous charging (which produces lower hydrogen fugacity) creates ∼22% higher activation energy for hydrogen trapping compared with cathodic charging (which produces higher hydrogen fugacity). These results are due to the different effects on the hydrogen behavior in LDS which causes a major difference in the hydrogen contents and different hydrogen assisted phase transitions. The highest activation energy value in the cathodic charged sample was ascribed to the dominant phase transformation of γ → γ{sup ∗}, whereas in the gaseous charged sample it was ascribed to the dominant formation of intermetallic compound, sigma (σ). The relation between hydrogen distribution in LDS and hydrogen trapping mechanism is discussed in details. - Highlights: • The relation between hydrogen distribution and trapping in LDS is discussed. • Hydrogen's initial state in LDS causes different microstructural changes. • Gaseous charged LDS creates higher trapping energy compared to cathodic charged LDS. • The dominant phase transformation in

Hot vacuum outgassing to ensure low hydrogen content in MOX fuel pellets for thermal reactors

International Nuclear Information System (INIS)

Majumdar, S.; Nair, M.R.; Kumar, Arun

1983-01-01

Hot vacuum outgassing treatment to ensure low hydrogen content in Mixed Oxide Fuel (MOX) pellets for thermal reactors has been described. Hypostoichiometric sintered MOX pellets retain more hydrogen than UO 2 pellets. The hydrogen content further increases with the addition of admixed lubricant and pore formers. However, low hydrogen content in the MOX pellets can be ensured by a hot vacuum outgassing treatment at a temperature between 773K to 823K for 2 hrs. (author)

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

Quantification of 2,5-dimethyl-4-hydroxy-3(2H)-furanone using solid-phase extraction and direct microvial insert thermal desorption gas chromatography-mass spectrometry.

Science.gov (United States)

Du, Xiaofen; Qian, Michael

2008-10-24

A GC-MS method for the determination of furaneol in fruit juice was developed using Lichrolut-EN solid-phase extraction (SPE) coupled to microvial insert thermal desorption. Lichrolut-EN can effectively extract furaneol from juice, and had much less retention for pigments and other non-volatiles than HLB and C18 columns. The furaneol can be completely eluted out from the Lichrolut-EN SPE column with 1mL of methanol, which can be directly analyzed on GC-MS using an automated large volume microvial insert thermal desorption technique without further purification and concentration. The method is sensitive, has good recovery (98%) and reproducibility (CVfuraneol in some commonly grown strawberry, raspberry, and blackberry cultivars in Pacific Northwest of the United States was determined. Strawberries had the highest concentration of furaneol with 'Totem' and 'Pinnacle' cultivars over 13mgkg(-1) fruit. 'Marion' blackberry had 5 times more furaneol than 'Black Diamond', and 16 times more than 'Thornless Evergreen' blackberry. Raspberries had furaneol concentration ranged from 0.8 to 1.1mgkg(-1) fruit.

Experiments on the thermalization of slow neutrons by liquid hydrogen (1962)

International Nuclear Information System (INIS)

Cribier, D.; Jacrot, B.; Lacaze, A.; Roubeau, P.

1962-01-01

In order to increase the flux of neutrons of long wave-length (λ > 4 A) emerging from a channel in the EL-3, a liquid hydrogen device was introduced into a channel of the reactor (Channel H 1 ). The principle of the device is simple. A volume of liquid hydrogen is introduced as close as possible to the reactor core into a region of intense isotropic flux. This hydrogen slows down the slow neutrons; because of the very small mean free diffusion path of slow in hydrogen, this slowing down is considerable even in a small volume of liquid hydrogen, and the spectrum temperature of neutrons emerging from the volume of liquid hydrogen can therefore be shifted. The intensity gain for neutrons with a wave length λ, is a G (λ) function which, for perfect thermalization and ignoring capture, is expressed by: G (λ) = 225 exp (- 45.3/λ 2 ), assuming a temperature of 300 deg. K for the neutrons before cooling and is 20 deg. K after cooling. For a wave-length of 5 A, the theoretical maximum gain of thus about 37. (authors) [fr

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)

Kinetic compensation effect in the thermal desorption of a binary gas mixture

Science.gov (United States)

Zuniga-Hansen, Nayeli; Silbert, Leonardo E.; Calbi, M. Mercedes

The kinetic compensation effect, observed in many different areas of science, is the systematic change in the magnitudes of the Arrhenius parameters Ea, the energy of activation and ν, the preexponential factor, as a response to external perturbing parameters. Its existence continues to be debated as it has not been explicitly demonstrated and its physical origins remain poorly understood. As part of a systematic study of different factors that alter the energy of activation during thermal desorption, we have performed numerical studies of the effects of adsorbate-adsorbate interactions on the Arrhenius parameters, as well as the effects of changes in surface morphology. Our results have consistently shown that there is a partial compensation effect between Ea and lnν and a tendency towards isokinetic equilibrium when the system transitions from an interacting to a non-interacting regime. In the present work we study the effects of the presence of two different chemical species. With our systematic study we expect to provide a deeper insight into the microscopic events that originate compensation effects, not only in our system, but also in other fields where these effects have been reported.

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

Anomalous low-temperature desorption from preirradiated rare gas solids

International Nuclear Information System (INIS)

Savchenko, E.V.; Gumenchuk, G.B.; Yurtaeva, E.M.; Belov, A.G.; Khyzhniy, I.V.; Frankowski, M.; Beyer, M.K.; Smith-Gicklhorn, A.M.; Ponomaryov, A.N.; Bondybey, V.E.

2005-01-01

The role for the exciton-induced defects in the stimulation of anomalous low-temperature desorption of the own lattice atoms from solid Ar and Ne preirradiated by an electron beam is studied. The free electrons from shallow traps-structural defects-was monitored by the measurements of a yield of the thermally induced exoelectron emission (TSEE). The reaction of recombination of self-trapped holes with electrons is considered as a source of energy needed for the desorption of atoms from the surface of preirradiated solids. A key part of the exciton-induced defects in the phenomenon observed is demonstrated

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 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

Round robin analyses of hydrogen isotope thin films standards

Energy Technology Data Exchange (ETDEWEB)

Banks, J.C. E-mail: jcbanks@sandia.gov; Browning, J.F.; Wampler, W.R.; Doyle, B.L.; LaDuca, C.A.; Tesmer, J.R.; Wetteland, C.J.; Wang, Y.Q

2004-06-01

Hydrogen isotope thin film standards have been manufactured at Sandia National Laboratories for use by the materials characterization community. Several considerations were taken into account during the manufacture of the ErHD standards, with accuracy and stability being the most important. The standards were fabricated by e-beam deposition of Er onto a Mo substrate and the film stoichiometrically loaded with hydrogen and deuterium. To determine the loading accuracy of the standards two random samples were measured by thermal desorption mass spectrometry and atomic absorption spectrometry techniques with a stated combined accuracy of {approx}1.6% (1{sigma}). All the standards were then measured by high energy RBS/ERD and RBS/NRA with the accuracy of the techniques {approx}5% (1{sigma}). The standards were then distributed to the IBA materials characterization community for analysis. This paper will discuss the suitability of the standards for use by the IBA community and compare measurement results to highlight the accuracy of the techniques used.

Defects in TiN and HfN studied by helium thermal desorption spectrometry

International Nuclear Information System (INIS)

Hoondert, W.H.B.; Thijsse, B.J.; Beuckel, A. van den

1994-01-01

Point defects in sub-stoichiometric TiN 1-x and HfN 1-x were investigated by helium thermal desorption spectrometry (300-1800K) following He + ion implantation at energies up to 3000eV. It was found that the low energy spectra are dominated by helium dissociating from the structural vacancies on the nitrogen sublattice; the activation energy for dissociation is 2.2eV for TiN. Above a few hundred electron volts the ions begin to produce several other types of defects, from which helium dissociates with activation energies in the range 2.6-4.0eV. The identity of these defects is discussed. The results for the two nitrides were similar in many respects. The most significant difference observed is that in TiN low energy He + ions generate damage on the N sublattice of a type that is not observed for HfN. Activation energies for HfN are found to be consistently 0.7eV lower than for TiN. ((orig.))

Improved thermal stability of gas-phase Mg nanoparticles for hydrogen storage

NARCIS (Netherlands)

Krishnan, Gopi; Palasantzas, G.; Kooi, B. J.

2010-01-01

This work focuses on improving the thermal stability of Mg nanoparticles (NPs) for use in hydrogen storage. Three ways are investigated that can achieve this goal. (i) Addition of Cu prevents void formation during NP production and reduces the fast evaporation/voiding of Mg during annealing. (ii)

Survival and growth of Alfalfa (Medicago sativa l.) inoculated with an am fungus (Glomus intraradices) in contaminated soils treated with two different remediation technologies (bio-pile and thermal desorption)

International Nuclear Information System (INIS)

Norini, M.P.; Beguiristain, Th.; Leyval, C.

2005-01-01

Polycyclic aromatic hydrocarbons (PAHs) represent a group of persistent and toxic soil pollutants that are of major public concern due to their mutagenic and carcinogenic property. Phyto-remediation is the use of plants and their associated microorganisms for remediation of polluted soils. Phyto-remediation could be used in conjunction with other remediation technologies to reduce the contamination to safe levels and maintain or restore soil physico-chemical and biological properties. Most plant species form mycorrhizas with symbiotic fungi. It was shown that AM fungi enhance survival and plant growth in PAH contaminated soils. Mycorrhizal fungi also enhance the biotransformation or biodegradation of PAH, although the effect differed between soils. A rhizosphere and myco-rhizosphere gradient of PAH concentrations was observed, with decreased PAH concentration with decreased distance to roots. Different microbial communities were found in the rhizosphere of AM and non-mycorrhizal plants in comparison to bulk soil, suggesting that AM could affect PAH degradation by changing microbial communities. We investigated the effect of mycorrhizal fungi and nutrients on the ability of alfalfa to grow on soil contaminated with PAHs before and after two remediation treatments. We used soil from an industrial site (Homecourt, North East part of France) highly contaminated with PAH (2000 mg kg -1 ), which has been partially treated by two different remediation technologies (bio-pile and thermal desorption). The bio-pile treatment consisted of piling the contaminated soil with stimulation of aerobic microbial activity by aeration and addition of nutrient solution, and reduced PAH concentration to around 300 mg kg-1. With the thermal desorption treatment the soil was heated to around 500 deg. C so that PAH vaporized and were separated from the soil. The residual PAH concentration in soil was 40 mg kg -1 . Treated and non-treated contaminated soil was planted with alfalfa (Medicago

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.)

Rapid hydrogen gas generation using reactive thermal decomposition of uranium hydride.

Energy Technology Data Exchange (ETDEWEB)

Kanouff, Michael P.; Van Blarigan, Peter; Robinson, David B.; Shugard, Andrew D.; Gharagozloo, Patricia E.; Buffleben, George M.; James, Scott Carlton; Mills, Bernice E.

2011-09-01

Oxygen gas injection has been studied as one method for rapidly generating hydrogen gas from a uranium hydride storage system. Small scale reactors, 2.9 g UH{sub 3}, were used to study the process experimentally. Complimentary numerical simulations were used to better characterize and understand the strongly coupled chemical and thermal transport processes controlling hydrogen gas liberation. The results indicate that UH{sub 3} and O{sub 2} are sufficiently reactive to enable a well designed system to release gram quantities of hydrogen in {approx} 2 seconds over a broad temperature range. The major system-design challenge appears to be heat management. In addition to the oxidation tests, H/D isotope exchange experiments were performed. The rate limiting step in the overall gas-to-particle exchange process was found to be hydrogen diffusion in the {approx}0.5 {mu}m hydride particles. The experiments generated a set of high quality experimental data; from which effective intra-particle diffusion coefficients can be inferred.

Correction factor to determine total hydrogen+deuterium concentration obtained by inert gas fusion-thermal conductivity detection (IGF- TCD) technique

International Nuclear Information System (INIS)

Ramakumar, K.L.; Sesha Sayi, Y.; Shankaran, P.S.; Chhapru, G.C; Yadav, C.S.; Venugopal, V.

2004-01-01

The limitation of commercially available dedicated equipment based on Inert Gas Fusion- Thermal Conductivity Detection (IGF - TCD) for the determination of hydrogen+deuterium is described. For a given molar concentration, deuterium is underestimated vis a vis hydrogen because of lower thermal conductivity and not considering its molecular weight in calculations. An empirical correction factor based on the differences between the thermal conductivities of hydrogen, deuterium and the carrier gas argon, and the mole fraction of deuterium in the sample has been derived to correct the observed hydrogen+deuterium concentration. The corrected results obtained by IGF - TCD technique have been validated by determining hydrogen and deuterium contents in a few samples using an independent method based on hot vacuum extraction-quadrupole mass spectrometry (HVE-QMS). Knowledge of mole fraction of deuterium (XD) is necessary to effect the correction. The correction becomes insignificant at low X D values (XD < 0.2) as the precision in the IGF measurements is comparable with the extent of correction. (author)

Desorption dynamics of deuterium in CuCrZr alloy

Science.gov (United States)

Thi Nguyen, Lan Anh; Lee, Sanghwa; Noh, S. J.; Lee, S. K.; Park, M. C.; Shu, Wataru; Pitcher, Spencer; Torcy, David; Guillermain, David; Kim, Jaeyong

2017-12-01

Desorption behavior of deuterium (D2) in CuCrZr alloy was investigated considering sample thickness, loading and baking temperature of deuterium followed by the ITER scopes. Cylindrical specimens of 1, 3, 5 mm thick with 4 mm diameter were exposed to deuterium at a pressure of 25 bar at 120, 240 and 350 °C for 24 h, then baked at 800 °C in a vacuum chamber maintained at a pressure lower than 10-7 Torr. Deuterium desorption characteristics such as desorption rate and amount of deuterium in the sample were estimated by analyzing the desorption peaks monitored with a residual gas analyzer (RGA), and the trapping energy of deuterium was calculated using thermal desorption spectroscopy (TDS). Secondary ion mass spectroscopy (SIMS) results showed that deuterium atoms embedded in the sample at a depth of less than 15 μm and desorbed as low as 400 °C. All absorbed deuterium atoms in the specimen were completely retrieved by dynamic pumping at 800 °C in 15 min. The desorption rate of deuterium per unit area was inversely proportional to the increment of the thickness of the sample, and was proportional to the loading temperature. Based on the assumption that a uniform distribution of interstitial sites for deuterium follows the Femi-Dirac statistics, the result of TDS demonstrated that the CuCrZr alloy has two types of trapping energies, which were estimated to be 62 and 79 kJ/mol.

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.

Mechanochemical synthesis of nanostructured chemical hydrides in hydrogen alloying mills

International Nuclear Information System (INIS)

Wronski, Z.; Varin, R.A.; Chiu, C.; Czujko, T.; Calka, A.

2007-01-01

Mechanical alloying of magnesium metal powders with hydrogen in specialized hydrogen ball mills can be used as a direct route for mechanochemical synthesis of emerging chemical hydrides and hydride mixtures for advanced solid-state hydrogen storage. In the 2Mg-Fe system, we have successfully synthesized the ternary complex hydride Mg 2 FeH 6 in a mixture with nanometric Fe particles. The mixture of complex magnesium-iron hydride and nano-iron released 3-4 wt.%H 2 in a thermally programmed desorption experiment at the range 285-295 o C. Milling of the Mg-2Al powder mixture revealed a strong competition between formation of the Al(Mg) solid solution and the β-MgH 2 hydride. The former decomposes upon longer milling as the Mg atoms react with hydrogen to form the hydride phase, and drive the Al out of the solid solution. The mixture of magnesium dihydride and nano-aluminum released 2.1 wt.%H 2 in the temperature range 329-340 o C in the differential scanning calorimetry experiment. The formation of MgH 2 was suppressed in the Mg-B system; instead, a hydrogenated amorphous phase (Mg,B)H x , was formed in a mixture with nanometric MgB 2 . Annealing of the hydrogen-stabilized amorphous mixture produced crystalline MgB 2

Improved electrical stability of CdS thin film transistors through Hydrogen-based thermal treatments

KAUST Repository

Salas Villaseñor, Ana L.

2014-06-01

Thin film transistors (TFTs) with a bottom-gate configuration were fabricated using a photolithography process with chemically bath deposited (CBD) cadmium sulfide (CdS) films as the active channel. Thermal annealing in hydrogen was used to improve electrical stability and performance of the resulting CdS TFTs. Hydrogen thermal treatments results in significant V T instability (V T shift) improvement while increasing the I on/I off ratio without degrading carrier mobility. It is demonstrated that after annealing V T shift and I on/I off improves from 10 V to 4.6 V and from 105 to 10 9, respectively. Carrier mobility remains in the order of 14.5 cm2 V s-1. The reduced V T shift and performance is attributed to a reduction in oxygen species in the CdS after hydrogen annealing, as evaluated by Fourier transform infrared spectroscopy (FTIR). © 2014 IOP Publishing Ltd.

Improved electrical stability of CdS thin film transistors through Hydrogen-based thermal treatments

KAUST Repository

Salas Villaseñ or, Ana L.; Mejia, Israel I.; Sotelo-Lerma, Mé rida; Guo, Zaibing; Alshareef, Husam N.; Quevedo-Ló pez, Manuel Angel Quevedo

2014-01-01

Thin film transistors (TFTs) with a bottom-gate configuration were fabricated using a photolithography process with chemically bath deposited (CBD) cadmium sulfide (CdS) films as the active channel. Thermal annealing in hydrogen was used to improve electrical stability and performance of the resulting CdS TFTs. Hydrogen thermal treatments results in significant V T instability (V T shift) improvement while increasing the I on/I off ratio without degrading carrier mobility. It is demonstrated that after annealing V T shift and I on/I off improves from 10 V to 4.6 V and from 105 to 10 9, respectively. Carrier mobility remains in the order of 14.5 cm2 V s-1. The reduced V T shift and performance is attributed to a reduction in oxygen species in the CdS after hydrogen annealing, as evaluated by Fourier transform infrared spectroscopy (FTIR). © 2014 IOP Publishing Ltd.

Propagation of sound and thermal waves in an ionizing-recombining hydrogen plasma: Revision of results

International Nuclear Information System (INIS)

Di Sigalotti, Leonardo G.; Sira, Eloy; Tremola, Ciro

2002-01-01

The propagation of acoustic and thermal waves in a heat conducting, hydrogen plasma, in which photoionization and photorecombination [H + +e - H+hν(χ)] processes are progressing, is re-examined here using linear analysis. The resulting dispersion equation is solved analytically and the results are compared with previous solutions for the same plasma model. In particular, it is found that wave propagation in a slightly and highly ionized hydrogen plasma is affected by crossing between acoustic and thermal modes. At temperatures where the plasma is partially ionized, waves of all frequencies propagate without the occurrence of mode crossing. These results disagree with those reported in previous work, thereby leading to a different physical interpretation of the propagation of small linear disturbances in a conducting, ionizing-recombining, hydrogen plasma

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.

Thermal soil remediation

International Nuclear Information System (INIS)

Nelson, D.

1999-01-01

The environmental properties and business aspects of thermal soil remediation are described. Thermal soil remediation is considered as being the best option in cleaning contaminated soil for reuse. The thermal desorption process can remove hydrocarbons such as gasoline, kerosene and crude oil, from contaminated soil. Nelson Environmental Remediation (NER) Ltd. uses a mobile thermal desorption unit (TDU) with high temperature capabilities. NER has successfully applied the technology to target heavy end hydrocarbon removal from Alberta's gumbo clay in all seasons. The TDU consist of a feed system, a counter flow rotary drum kiln, a baghouse particulate removal system, and a secondary combustion chamber known as an afterburner. The technology has proven to be cost effective and more efficient than bioremediation and landfarming

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

Room temperature and thermal decomposition of magnesium hydride/deuteride thin films

Energy Technology Data Exchange (ETDEWEB)

Ares, J.R.; Leardini, F.; Bodega, J.; Macia, M.D.; Diaz-Chao, P.; Ferrer, I.J.; Fernandez, J.F.; Sanchez, C. [Universidad Autonoma de Madrid (Spain). Lab. de Materiales de Interes en Energias Renovables

2010-07-01

Magnesium hydride (MgH{sub 2}) can be considered an interesting material to store hydrogen as long as two main drawbacks were solved: (i) its high stability and (ii) slow (de)hydriding kinetics. In that context, magnesium hydride films are an excellent model system to investigate the influence of structure, morphology and dimensionality on kinetic and thermodynamic properties. In the present work, we show that desorption mechanism of Pd-capped MgH{sub 2} at room temperature is controlled by a bidimensional interphase mechanism and a similar rate step limiting mechanism is observed during thermal decomposition of MgH{sub 2}. This mechanism is different to that occurring in bulk MgH{sub 2} (nucleation and growth) and obtained activation energies are lower than those reported in bulk MgH{sub 2}. We also investigated the Pd-capping properties upon H-absorption/desorption by means of RBS and isotope experiments. (orig.)

Non-thermal escape of molecular hydrogen from Mars

Science.gov (United States)

Gacesa, M.; Zhang, P.; Kharchenko, V.

2012-05-01

We present a detailed theoretical analysis of non-thermal escape of molecular hydrogen from Mars induced by collisions with hot atomic oxygen from the Martian corona. To accurately describe the energy transfer in O + H2(v, j) collisions, we performed extensive quantum-mechanical calculations of state-to-state elastic, inelastic, and reactive cross sections. The escape flux of H2 molecules was evaluated using a simplified 1D column model of the Martian atmosphere with realistic densities of atmospheric gases and hot oxygen production rates for low solar activity conditions. An average intensity of the non-thermal escape flux of H2 of 1.9 × 105 cm-2s-1 was obtained considering energetic O atoms produced in dissociative recombinations of O2+ ions. Predicted ro-vibrational distribution of the escaping H2 was found to contain a significant fraction of higher rotational states. While the non-thermal escape rate was found to be lower than Jeans rate for H2 molecules, the non-thermal escape rates of HD and D2 are significantly higher than their respective Jeans rates. The accurate evaluation of the collisional escape flux of H2 and its isotopes is important for understanding non-thermal escape of molecules from Mars, as well as for the formation of hot H2 Martian corona. The described molecular ejection mechanism is general and expected to contribute to atmospheric escape of H2 and other light molecules from planets, satellites, and exoplanetary bodies.

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

Decay of the pulsed thermal neutron flux in two-zone hydrogenous systems - Monte Carlo simulations using MCNP standard data libraries

International Nuclear Information System (INIS)

Wiacek, Urszula; Krynicka, Ewa

2006-01-01

Pulsed neutron experiments in two-zone spherical and cylindrical geometry has been simulated using the MCNP code. The systems are built of hydrogenous materials. The inner zone is filled with aqueous solutions of absorbers (H 3 BO 3 or KCl). It is surrounded by the outer zone built of Plexiglas. The system is irradiated with the pulsed thermal neutron flux and the thermal neutron decay in time is observed. Standard data libraries of the thermal neutron scattering cross-sections of hydrogen in hydrogenous substances have been used to simulate the neutron transport. The time decay constant of the fundamental mode of the thermal neutron flux determined in each simulation has been compared with the corresponding result of the real pulsed neutron experiment

Erbium hydride decomposition kinetics.

Energy Technology Data Exchange (ETDEWEB)

Ferrizz, Robert Matthew

2006-11-01

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

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

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)

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.

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 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.

Desorption, dissociation and orientation of oxygen admolecules on a reconstructed platinum(110)(1x2) surface studied by thermal desorption and near-edge X-ray-absorption fine-structure

International Nuclear Information System (INIS)

Ohno, Yuichi; Matsushima, Tatsuo; Tanaka, Shin-ichiro; Kamada, Masao

1993-01-01

The desorption, dissociation and orientation of oxygen admolecules on a reconstructed Pt(110)(1x2) were studied by means of TDS combined with isotope tracer, NEXAFS, and angle-resolved TDS. The admolecules below half a monolayer lie on the bottom of the trough, being oriented along it. The molecules adsorbed additionally are lying on declining terraces. The desorption flux of the former species shows a simple cosine distribution, suggesting that the molecule is not localized on the bottom in the desorption event. (author)

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.

Techno-economic study of hydrogen production by high temperature electrolysis and coupling with different thermal energy sources

International Nuclear Information System (INIS)

Rivera-Tinoco, R.

2009-03-01

This work focuses on the techno-economic study of massive hydrogen production by the High Temperature Electrolysis (HTE) process and also deals with the possibility of producing the steam needed in the process by using different thermal energy sources. Among several sources, those retained in this study are the biomass and domestic waste incineration units, as well as two nuclear reactors (European Pressurised water Reactor - EPR and Sodium Fast Reactor - SFR). Firstly, the technical evaluation of the steam production by each of these sources was carried out. Then, the design and modelling of the equipments composing the process, specially the electrolysers (Solid Oxides Electrolysis Cells), are presented. Finally, the hydrogen production cost for each energy sources coupled with the HTE process is calculated. Moreover, several sensibility studies were performed in order to determine the process key parameter and to evaluate the influence of the unit size effect, the electric energy cost, maintenance, the cells current density, their investment cost and their lifespan on the hydrogen production cost. Our results show that the thermal energy cost is much more influent on the hydrogen production cost than the steam temperature at the outlet stream of the thermal source. It seems also that the key parameters for this process are the electric energy cost and the c ells lifespan. The first one contributes for more than 70% of the hydrogen production cost. From several cell lifespan values, it seems that a 3 year value, rather than 1 year, could lead to a hydrogen production cost reduced on 34%. However, longer lifespan values going from 5 to 10 years would only lead to a 8% reduction on the hydrogen production cost. (author)

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)

Hydrogenation of surface carbon on alumina-supported nickel

Energy Technology Data Exchange (ETDEWEB)

Mccarthy, J.G.; Wise, H.

1979-05-01

The methanation of carbon deposited by CO or ethylene decomposition on Girdler G-65 catalyst (25Vertical Bar3< nickel, 8Vertical Bar3< alkali, mostly CaO, 4Vertical Bar3< C as graphite, on alumina) was studied by temperature-programed desorption and temperature-programed surface reaction. Four types of carbon were identified: ..cap alpha..-carbon consisted of isolated carbon atoms bonded to nickel and reacting with hydrogen at 470/sup 0/ +/- 20/sup 0/K; ..gamma..-carbon was probably a bulk carbide, most likely Ni/sub 3/C, which had a reaction peak at 550/sup 0/K; ..beta..-carbon consisted of amorphous, polymerized carbon, which had a reaction peak at 680/sup 0/K; and an unreactive crystalline graphite-like species. The ..cap alpha..-form was thermally unstable and transformed into the ..beta..-form above 600/sup 0/K. Both ..cap alpha..- and ..beta..-forms slowly converted to inert graphite above 600/sup 0/K. The evidence suggested that synthesis gas methanation proceeds by dissociative adsorption of CO as the rate-determining step which forms a very reactive carbon adatom state (..cap alpha..') which converts to the ..cap alpha..-state in the absence of hydrogen and to methane in the presence of hydrogen.

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.)

Hydrogen sulfide toxicity in a thermal spring: a fatal outcome.

Science.gov (United States)

Daldal, Hale; Beder, Bayram; Serin, Simay; Sungurtekin, Hulya

2010-08-01

Hydrogen sulfide (H(2)S) is a toxic gas with the smells of "rotten egg"; its toxic effects are due to the blocking of cellular respiratory enzymes leading to cell anoxia and cell damage. We report two cases with acute H(2)S intoxication caused by inhalation of H(2)S evaporated from the water of a thermal spring. Two victims were found in a hotel room were they could take a thermal bath. A 26-year-old male was found unconscious; he was resuscitated, received supportive treatment and survived. A 25-year-old female was found dead. Autopsy showed diffuse edema and pulmonary congestion. Toxicological blood analysis of the female revealed the following concentrations: 0.68 mg/L sulfide and 0.21 mmol/L thiosulfate. The urine thiosulfate concentration was normal. Forensic investigation established that the thermal water was coming from the hotel's own illegal well. The hotel was closed. This report highlights the danger of H(2)S toxicity not only for reservoir and sewer cleaners, but also for individuals bathing in thermal springs.

Thermal mathematical modeling of a multicell common pressure vessel nickel-hydrogen battery

Science.gov (United States)

Kim, Junbom; Nguyen, T. V.; White, R. E.

1992-01-01

A two-dimensional and time-dependent thermal model of a multicell common pressure vessel (CPV) nickel-hydrogen battery was developed. A finite element solver called PDE/Protran was used to solve this model. The model was used to investigate the effects of various design parameters on the temperature profile within the cell. The results were used to help find a design that will yield an acceptable temperature gradient inside a multicell CPV nickel-hydrogen battery. Steady-state and unsteady-state cases with a constant heat generation rate and a time-dependent heat generation rate were solved.

Segregation of O2 and CO on the surface of dust grains determines the desorption energy of O2

Science.gov (United States)

Noble, J. A.; Diana, S.; Dulieu, F.

2015-12-01

Selective depletion towards pre-stellar cores is still not understood. The exchange between the solid and gas phases is central to this mystery. The aim of this paper is to show that the thermal desorption of O2 and CO from a submonolayer mixture is greatly affected by the composition of the initial surface population. We have performed thermally programmed desorption (TPD) experiments on various submonolayer mixtures of O2 and CO. Pure O2 and CO exhibit almost the same desorption behaviour, but their desorption differs strongly when mixed. Pure O2 is slightly less volatile than CO, while in mixtures, O2 desorbs earlier than CO. We analyse our data using a desorption law linking competition for binding sites with desorption, based on the assumption that the binding energy distribution of both molecules is the same. We apply Fermi-Dirac statistics in order to calculate the adsorption site population distribution, and derive the desorbing fluxes. Despite its simplicity, the model reproduces the observed desorption profiles, indicating that competition for adsorption sites is the reason for lower temperature O2 desorption. CO molecules push-out or `dislodge' O2 molecules from the most favourable binding sites, ultimately forcing their early desorption. It is crucial to consider the surface coverage of dust grains in any description of desorption. Competition for access to binding sites results in some important discrepancies between similar kinds of molecules, such as CO and O2. This is an important phenomenon to be investigated in order to develop a better understanding of the apparently selective depletion observed in dark molecular clouds.

Thermal coupling of a high temperature PEM fuel cell with a complex hydride tank

DEFF Research Database (Denmark)

Pfeifer, P.; Wall, C.; Jensen, Jens Oluf

2009-01-01

the possibilities of a thermal coupling of a high temperature PEM fuel cell operating at 160-200 degrees C. The starting temperatures and temperature hold-times before starting fuel cell operation, the heat transfer characteristics of the hydride storage tanks, system temperature, fuel cell electrical power......Sodium alanate doped with cerium catalyst has been proven to have fast kinetics for hydrogen ab- and de-sorption as well as a high gravimetric storage density around 5 wt%. The kinetics of hydrogen sorption can be improved by preparing the alanate as nanocrystalline material. However, the second...... decomposition step, i.e. the decomposition of the hexahydride to sodium hydride and aluminium which refers to 1.8 wt% hydrogen is supposed to happen above 110 degrees C. The discharge of the material is thus limited by the level of heat supplied to the hydride storage tank. Therefore, we evaluated...

ε-Polylysine-based thermo-responsive adsorbents for immunoglobulin adsorption-desorption under mild conditions.

Science.gov (United States)

Maruyama, Masashi; Shibuya, Keisuke

2017-08-22

Thermo-responsive adsorbents for immunoglobulin G (IgG) employing ε-polylysine (EPL) as a polymer backbone were developed. The introduction of mercaptoethylpyridine (MEP) as an IgG-binding ligand and hydrophobization of side chains afforded thermo-responsive IgG adsorbents, whose thermo-responsive IgG desorption ratio was up to 88% (EPL/MEP derivative 3m). The changes in surface densities of active MEP groups, which are caused by thermal conformational changes of the adsorbents, play key roles for IgG desorption. Although a trade-off of IgG adsorption capacity and IgG desorption ratio was observed, the present study offers a novel molecular design for thermo-responsive adsorbents with high synthetic accessibility and potentially low toxicity.

Neutralized solar wind ahead of the Earth's magnetopause as contribution to non-thermal exospheric hydrogen

Directory of Open Access Journals (Sweden)

H. J. Fahr

2018-03-01

Full Text Available In a most recent paper by Qin and Waldrop (2016, it had been found that the scale height of hydrogen in the upper exosphere of the Earth, especially during solar minimum conditions, appears to be surprisingly large. This indicates that during minimum conditions when exobasic temperatures should be small, large exospheric H-scale heights predominate. They thus seem to indicate the presence of a non-thermal hydrogen component in the upper exosphere. In the following parts of the paper we shall investigate what fraction of such expected hot hydrogen atoms could have their origin from protons of the shocked solar wind ahead of the magnetopause converted into energetic neutral atoms (ENAs via charge-exchange processes with normal atmospheric, i.e., exospheric hydrogen atoms that in the first step evaporate from the exobase into the magnetosheath plasma region. We shall show that, dependent on the sunward location of the magnetopause, the density of these types of non-thermal hydrogen atoms (H-ENAs becomes progressively comparable with the density of exobasic hydrogen with increasing altitude. At low exobasic heights, however, their contribution is negligible. At the end of this paper, we finally study the question of whether the H-ENA population could even be understood as a self-consistency phenomenon of the H-ENA population, especially during solar activity minimum conditions, i.e., H-ENAs leaving the exosphere being replaced by H-ENAs injected into the exosphere.

Neutralized solar wind ahead of the Earth's magnetopause as contribution to non-thermal exospheric hydrogen

Science.gov (United States)

Fahr, Hans J.; Nass, Uwe; Dutta-Roy, Robindro; Zoennchen, Jochen H.

2018-03-01

In a most recent paper by Qin and Waldrop (2016), it had been found that the scale height of hydrogen in the upper exosphere of the Earth, especially during solar minimum conditions, appears to be surprisingly large. This indicates that during minimum conditions when exobasic temperatures should be small, large exospheric H-scale heights predominate. They thus seem to indicate the presence of a non-thermal hydrogen component in the upper exosphere. In the following parts of the paper we shall investigate what fraction of such expected hot hydrogen atoms could have their origin from protons of the shocked solar wind ahead of the magnetopause converted into energetic neutral atoms (ENAs) via charge-exchange processes with normal atmospheric, i.e., exospheric hydrogen atoms that in the first step evaporate from the exobase into the magnetosheath plasma region. We shall show that, dependent on the sunward location of the magnetopause, the density of these types of non-thermal hydrogen atoms (H-ENAs) becomes progressively comparable with the density of exobasic hydrogen with increasing altitude. At low exobasic heights, however, their contribution is negligible. At the end of this paper, we finally study the question of whether the H-ENA population could even be understood as a self-consistency phenomenon of the H-ENA population, especially during solar activity minimum conditions, i.e., H-ENAs leaving the exosphere being replaced by H-ENAs injected into the exosphere.

Hydrogen Storage Characteristics of CNT doped NaAlH4

International Nuclear Information System (INIS)

Pukazhselvan, D.; Sterlin Leo Hudson, M.; Bipin Kumar Gupta; Srivastava, O.N.

2006-01-01

The current Hydrogen based energy infrastructure required a high energy density consumer friendly hydrogen storage media. Although the desired goals for the hydrogen fueled vehicular transport has not yet met by any hydrogen storage material, complex Sodium Alanate is said to be a promising candidate under this demand due to its high hydrogen storage capacity and the thermodynamically permissible reversible hydrogen storage capacity. However its poor sorption behavior under moderate conditions (NaAlH 4 →Na 3 AlH 6 ; 3.7 wt % vs 50 hrs at ∼170 C and Na 3 AlH 6 →NaH; 1.85 wt % vs 30 hrs at ∼220 C) urges their limited uses in ages. But these limitations can be removed by using catalysts particularly transition elements but the location of catalyst in NaAlH 4 matrix and the possible mechanism is not yet clearly understood. The aim of the present investigation is to improve the overall sorption characteristics of NaAlH 4 by a new light weighted high surface area (1315 sq mtr/gm) material (CNT) admixing and to obtain a best doping level to NaAlH 4 . So far only Ti has been attempted as a suitable catalyst. It is believed that the high surface area of CNT can provide an additional solid-gas (H 2 ) surface/interface and it can produce thermal contact between grains (thermal conductivity Kth of MWCNT: 3000 w/k and Kth of NaAlH 4 : 0.32 w/k) for stimulating their thermally activated dissociation in NaAlH 4 . In parallel with this approach XRD of NaAlH 4 reveals that there was no change in lattice structure after doping by CNT, SEM picture depicts that CNT precipitation in grain surfaces. Catalytic concentration of various mole % of x values finds that x = 8 is the best doping level as it gives 3.3 wt % of hydrogen within 2 hrs. The comparative sorption behavior with Ti:NaAlH 4 also shows CNTs as an optimum alternative catalyst to NaAlH 4 and besides this CNT doped desorbed ingredients shown good re-hydrogenation behavior(3.7 wt % at 8. cycle and 4.2 wt % maximum at

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....

Development of a Microwave Regenerative Sorbent-Based Hydrogen Purifier

Science.gov (United States)

Wheeler, Richard R., Jr.; Dewberry, Ross H.; McCurry, Bryan D.; Abney, Morgan B.; Greenwood, Zachary W.

2016-01-01

This paper describes the design and fabrication of a Microwave Regenerative Sorbent-based Hydrogen Purifier (MRSHP). This unique microwave powered technology was developed for the purification of a hydrogen stream produced by the Plasma Pyrolysis Assembly (PPA). The PPA is a hydrogen recovery (from methane) post processor for NASA's Sabatier-based carbon dioxide reduction process. Embodied in the Carbon dioxide Reduction Assembly (CRA), currently aboard the International Space Station (ISS), the Sabatier reaction employs hydrogen to catalytically recover oxygen, in the form of water, from respiratory carbon dioxide produced by the crew. This same approach is base-lined for future service in the Air Revitalization system on extended missions into deep space where resupply is not practical. Accordingly, manned exploration to Mars may only become feasible with further closure of the air loop as afforded by the greater hydrogen recovery permitted by the PPA with subsequent hydrogen purification. By utilizing the well-known high sorbate loading capacity of molecular sieve 13x, coupled with microwave dielectric heating phenomenon, MRSHP technology is employed as a regenerative filter for a contaminated hydrogen gas stream. By design, freshly regenerated molecular sieve 13x contained in the MRSHP will remove contaminants from the effluent of a 1-CM scale PPA for several hours prior to breakthrough. By reversing flow and pulling a relative vacuum the MRSHP prototype then uses 2.45 GHz microwave power, applied through a novel coaxial antenna array, to rapidly heat the sorbent bed and drive off the contaminants in a short duration vacuum/thermal contaminant desorption step. Finally, following rapid cooling via room temperature cold plates, the MRSHP is again ready to serve as a hydrogen filter.

Thermal transformation of bioactive caffeic acid on fumed silica seen by UV-Vis spectroscopy, thermogravimetric analysis, temperature programmed desorption mass spectrometry and quantum chemical methods.

Science.gov (United States)

Kulik, Tetiana V; Lipkovska, Natalia O; Barvinchenko, Valentyna M; Palyanytsya, Borys B; Kazakova, Olga A; Dudik, Olesia O; Menyhárd, Alfréd; László, Krisztina

2016-05-15

Thermochemical studies of hydroxycinnamic acid derivatives and their surface complexes are important for the pharmaceutical industry, medicine and for the development of technologies of heterogeneous biomass pyrolysis. In this study, structural and thermal transformations of caffeic acid complexes on silica surfaces were studied by UV-Vis spectroscopy, thermogravimetric analysis, temperature programmed desorption mass spectrometry (TPD MS) and quantum chemical methods. Two types of caffeic acid surface complexes are found to form through phenolic or carboxyl groups. The kinetic parameters of the chemical reactions of caffeic acid on silica surface are calculated. The mechanisms of thermal transformations of the caffeic chemisorbed surface complexes are proposed. Thermal decomposition of caffeic acid complex chemisorbed through grafted ester group proceeds via three parallel reactions, producing ketene, vinyl and acetylene derivatives of 1,2-dihydroxybenzene. Immobilization of phenolic acids on the silica surface improves greatly their thermal stability. Copyright © 2016 Elsevier Inc. All rights reserved.

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 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.

Thermal desorption of deuterium from Be, and Be with helium bubbles

Energy Technology Data Exchange (ETDEWEB)

Fedorov, A.V.; Van Veen, A.; Busker, G.J. [Delft Univ. of Technology (Netherlands). Interfaculty Reactor Inst.

1998-01-01

Deuterium desorption measurements carried out on a single-crystalline beryllium sample are presented. Deuterium ions were implanted at room temperature at the energy of 0.7 and 1.2 keV up to doses ranging from 10{sup 19} to 3.6 x 10{sup 21} m{sup -2}. In order to eliminate the influence of the beryllium-oxide surface layer, before the implantation the surface of the sample was cleaned by argon sputtering. After the implantation the sample was annealed up to 1200 K at a constant rate of 10 K/s. Deuterium released from the sample was monitored by a calibrated quadrupole mass-spectrometer. The desorption spectra revealed two different contributions. One is a well defined and very narrow peak centered around 450 K. This peak is observed only at high implantation doses > 7.8 x 10{sup 20} m{sup -2}, which is close to the deuterium saturation limit of 0.3 D/Be and is related to deuterium release from blisters or interconnected bubbles. The activation energy of 1.1 eV and the threshold implantation dose are consistent with the values reported in literature. The second contribution in the release spectra is found in the temperature range from 600 to 900 K and is present throughout the whole range of the implantation doses. The activation energies corresponding to this release lie in the range between 1.8 and 2.5 eV and are ascribed to the release from deuterium-vacancy type of defects. In a number of experiments the deuterium implantation was preceded by helium implantation followed by partial annealing to create helium bubbles. The resulting deuterium desorption spectra indicate that deuterium detrapping from helium bubbles is characterized by an activation energy of 2.7 eV. (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....

Magnesium growth in magnesium deuteride thin films during deuterium desorption

Energy Technology Data Exchange (ETDEWEB)

Checchetto, R., E-mail: riccardo.checchetto@unitn.it [Dipartimento di Fisica and CNISM, Università di Trento, Via Sommarive 14, I-38123 Trento (Italy); Miotello, A. [Dipartimento di Fisica and CNISM, Università di Trento, Via Sommarive 14, I-38123 Trento (Italy); Mengucci, P.; Barucca, G. [Dipartimento di Fisica e Ingegneria dei Materiali e del Territorio, Università Politecnica delle Marche, I-60131 Ancona (Italy)

2013-12-15

Highlights: ► Highly oriented Pd-capped magnesium deuteride thin films. ► The MgD{sub 2} dissociation was studied at temperatures not exceeding 100 °C. ► The structure of the film samples was analyzed by XRD and TEM. ► The transformation is controlled by the re-growth velocity of the Mg layers. ► The transformation is thermally activated, activation energy value of 1.3 ± 0.1 eV. -- Abstract: Pd- capped nanocrystalline magnesium thin films having columnar structure were deposited on Si substrate by e-gun deposition and submitted to thermal annealing in D{sub 2} atmosphere to promote the metal to deuteride phase transformation. The kinetics of the reverse deuteride to metal transformation was studied by Thermal Desorption Spectroscopy (TDS) while the structure of the as deposited and transformed samples was analyzed by X-rays diffraction and Transmission Electron Microscopy (TEM). In Pd- capped MgD{sub 2} thin films the deuteride to metal transformation begins at the interface between un-reacted Mg and transformed MgD{sub 2} layers. The D{sub 2} desorption kinetics is controlled by MgD{sub 2}/Mg interface effects, specifically the re-growth velocity of the Mg layers. The Mg re-growth has thermally activated character and shows an activation energy value of 1.3 ± 0.1 eV.

A monoenergetic electron source generated by nuclear stimulated desorption

International Nuclear Information System (INIS)

Kelson, I.; Levy, Y.; Nir, D.; Haustein, P.E.

1994-01-01

A series of measurements of nuclear stimulated desorption was performed for 103 Ru, using thin ruthenium films irradiated by thermal neutrons. The magnitude, time dependence and electric charge state of the outgoing 103m Rh flux was investigated. The utilization of monoenergetic electrons accompanying the 103 Rh decay for thin film thickness measurement is considered. (Author)

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 production of hydrogen through the use of a 77 wt% Pd 23 wt% Ag membrane water gas shift reactor

Directory of Open Access Journals (Sweden)

Liberty N. Baloyi

2016-12-01

Full Text Available Hydrogen as an energy carrier has the potential to decarbonize the energy sector. This work presents the application of a palladium-silver (Pd–Ag membrane-based reactor. The membrane reactor which is made from Pd–Ag film supported by porous stainless steel (PSS is evaluated for the production of hydrogen and the potential replacement of the current two-stage Water-Gas Shift (WGS reaction by a single stage reaction. The permeability of a 20 μm Pd–Ag membrane reactor was examined at 320 °C, 380 °C and 430 °C. The effect of continuous hydrogen exposure on the Pd–Ag membrane at high temperature and low temperature was examined to investigate the thermal stability and durability of the membrane. During continuous operation to determine thermal stability, the membrane reactor exhibited stable hydrogen permeation at 320 °C for 120 h and unstable hydrogen permeation at 430 °C was observed. For the WGS reaction, the reactor was loaded with Ferrochrome catalyst. The membrane showed the ability to produce high purity hydrogen, with a CO conversion and an H2 recovery of 84% and 88%, respectively. The membrane suffered from hydrogen embrittlement due to desorption and adsorption of hydrogen on the membrane surface. SEM analysis revealed cracks that occurred on the surface of the membrane after hydrogen exposure. XRD analysis revealed lattice expansion after hydrogen loading which suggests the occurrence of phase change from α-phase to the more brittle β-phase.

Accumulation and release of implanted hydrogen from blisters in Si during the thermal treatment

International Nuclear Information System (INIS)

Aleksandrov, P.A.; Baranova, E.K.; Baranova, I.V.; Budaragin, V.V.; Litvinov, V.L.

2004-01-01

The processes of accumulation of ion implanted hydrogen in blisters in silicon and its release during the thermal treatment at 350-1020 deg C have been studied by optical techniques. It is established that accumulation of gaseous hydrogen inside blisters takes place at temperatures lower than ∼ 450-500 deg C and is accompanied by the growth of blisters thickness and deformation of their caps. At higher temperatures hydrogen leaves cavities and dissolves in silicon. Due to internal pressure dropping the elasticity deformed top layer partially relaxes, and the blister thickness decreases. Etching of the surface layer reveals the agglomerations of small voids ( [ru

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)

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.

Crystallite sizes of LiH before and after ball milling and thermal exposure

International Nuclear Information System (INIS)

Ortiz, Angel L.; Osborn, William; Markmaitree, Tippawan; Shaw, Leon L.

2008-01-01

The powder characteristics of lithium hydride (LiH) as a function of high-energy ball milling condition are systematically investigated via quantitative X-ray diffraction (XRD) analysis. The results obtained from the XRD analysis are compared with those attained from scanning electron microscopy (SEM), transmission electron microscopy (TEM), and specific surface area (SSA) analyses. The thermal stability of the ball-milled LiH is also investigated in order to provide physical insights into its cyclic stability in hydrogen sorption and desorption cycles. The results indicate that ball milling is effective in obtaining nano-crystalline LiH powder which is relatively stable with retention of nano-crystals after thermal exposure at 285 deg. C (equivalent to 0.58T m ) for 1 h. The good thermal stability observed is attributed to the presence of many pores in the agglomerates at the ball-milled condition. These pores effectively prevent crystal growth during the thermal exposure

Crystallite sizes of LiH before and after ball milling and thermal exposure

Energy Technology Data Exchange (ETDEWEB)

Ortiz, Angel L. [Departamento de Electronica e Ingenieria Electromecanica, Universidad de Extremadura, Badajoz (Spain); Osborn, William; Markmaitree, Tippawan [Department of Chemical, Materials and Biomolecular Engineering, University of Connecticut, 97 North Eagleville Road, U-3136 Storrs, CT 06269-3136 (United States); Shaw, Leon L. [Department of Chemical, Materials and Biomolecular Engineering, University of Connecticut, 97 North Eagleville Road, U-3136 Storrs, CT 06269-3136 (United States)], E-mail: leon.shaw@uconn.edu

2008-04-24

The powder characteristics of lithium hydride (LiH) as a function of high-energy ball milling condition are systematically investigated via quantitative X-ray diffraction (XRD) analysis. The results obtained from the XRD analysis are compared with those attained from scanning electron microscopy (SEM), transmission electron microscopy (TEM), and specific surface area (SSA) analyses. The thermal stability of the ball-milled LiH is also investigated in order to provide physical insights into its cyclic stability in hydrogen sorption and desorption cycles. The results indicate that ball milling is effective in obtaining nano-crystalline LiH powder which is relatively stable with retention of nano-crystals after thermal exposure at 285 deg. C (equivalent to 0.58T{sub m}) for 1 h. The good thermal stability observed is attributed to the presence of many pores in the agglomerates at the ball-milled condition. These pores effectively prevent crystal growth during the thermal exposure.

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

Promising SiC support for Pd catalyst in selective hydrogenation of acetylene to ethylene

Science.gov (United States)

Guo, Zhanglong; Liu, Yuefeng; Liu, Yan; Chu, Wei

2018-06-01

In this study, SiC supported Pd nanoparticles were found to be an efficient catalyst in acetylene selective hydrogenation reaction. The ethylene selectivity can be about 20% higher than that on Pd/TiO2 catalyst at the same acetylene conversion at 90%. Moreover, Pd/SiC catalyst showed a stable catalytic life at 65 °C with 80% ethylene selectivity. With the detailed characterization using temperature-programmed reduction (H2-TPR), powder X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), N2 adsorption/desorption analysis, CO-chemisorption and thermo-gravimetric analysis (TGA), it was found that SiC owns a lower surface area (22.9 m2/g) and a broad distribution of meso-/macro-porosity (from 5 to 65 nm), which enhanced the mass transfer during the chemical process at high reaction rate and decreased the residence time of ethylene on catalyst surface. Importantly, SiC support has the high thermal conductivity, which favored the rapid temperature homogenization through the catalyst bed and inhabited the over-hydrogenation of acetylene. The surface electronic density of Pd on Pd/SiC catalyst was higher than that on Pd/TiO2, which could promote desorption of ethylene from surface of the catalyst. TGA results confirmed a much less coke deposition on Pd/SiC catalyst.

Thermal Decomposition of Sodium Hydrogen Carbonate and Textural Features of Its Calcines

Czech Academy of Sciences Publication Activity Database

Hartman, Miloslav; Svoboda, Karel; Pohořelý, Michael; Šyc, Michal

2013-01-01

Roč. 52, č. 31 (2013), s. 10619-10626 ISSN 0888-5885 R&D Projects: GA MŠk(CZ) 7C11009 Grant - others:RFCS(XE) RFCR-CT-2010-00009 Institutional support: RVO:67985858 Keywords : thermal decomposition * sodium hydrogen carbonate * sodium bicarbonate Subject RIV: CI - Industrial Chemistry, Chemical Engineering Impact factor: 2.235, year: 2013

Micro-cutting of silicon implanted with hydrogen and post-implantation thermal treatment

Science.gov (United States)

Jelenković, Emil V.; To, Suet; Sundaravel, B.; Xiao, Gaobo; Huang, Hu

2016-07-01

It was reported that non-amorphizing implantation by hydrogen has a potential in improving silicon machining. Post-implantation high-temperature treatment will affect implantation-induced damage, which can have impact on silicon machining. In this article, a relation of a thermal annealing of hydrogen implanted in silicon to micro-cutting experiment is investigated. Hydrogen ions were implanted into 4″ silicon wafers with 175 keV, 150 keV, 125 keV and doses of 2 × 1016 cm-2, 2 × 1016 cm-2 and 3 × 1016 cm-2, respectively. In this way, low hydrogen atom-low defect concentration was created in the region less than ~0.8 μm deep and high hydrogen atom-high defect concentration was obtained at silicon depth of ~0.8-1.5 μm. The post-implantation annealing was carried out at 300 and 400 °C in nitrogen for 1 h. Physical and electrical properties of implanted and annealed samples were characterized by secondary ion mass spectroscopy (SIMS), X-ray diffraction (XRD), Rutherford backscattering (RBS) and nanoindentation. Plunge cutting experiment was carried out in and silicon crystal direction. The critical depth of cut and cutting force were monitored and found to be influenced by the annealing. The limits of hydrogen implantation annealing contribution to the cutting characteristics of silicon are discussed in light of implantation process and redistribution of hydrogen and defects generation during annealing process.

Surface modification and hydrogen isotope retention in CFC during plasma irradiation in the Tore Supra tokamak

International Nuclear Information System (INIS)

Begrambekov, L.; Brosset, C.; Bucalossi, J.; Delchambre, E.; Gunn, J.P.; Grisolia, C.; Lipa, M.; Loarer, T.; Mitteau, R.; Moner-Garbet, P.; Pascal, J.-Y.; Shigin, P.; Titov, N.; Tsitrone, E.; Vergazov, S.; Zakharov, A.

2007-01-01

The uniform layer with thickness at least 50-100 μm was found on the CFC tiles from the inboard midplane after more than four years of tokamak operation. The upper part of the uniform layer was amorphous, but at the depth of ∼5 μm a structure consisting of micro-size regions with aromatic chains located parallel to the surface was found. Gradual transition from uniform layer to underlying CFC structure was observed. The reciprocating material probe was used for installation of CFC samples in the Tore Supra deuterium plasma. The thermal desorptional spectra of these samples are compared with the spectra of the samples irradiated in the laboratory stand and with the spectra of hydrogenated carbon film. The peculiarities of hydrogen isotope trapping under plasma irradiation and at the atmosphere are presented and discussed