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Showing papers on "Hydrogen storage published in 2001"


Journal ArticleDOI
TL;DR: In this article, the hydrogen absorption and desorption kinetics of nanocomposite materials were determined with respect to a technical application, and the composite material containing Fe3O4 showed the fastest kinetics followed by V2O5, Mn2O4, Cr2O3, and TiO2.

717 citations


Journal ArticleDOI
TL;DR: A review of the hydrogen adsorption studies on activated carbons can be found in this article, where the authors provide a brief history of these studies and comments on the recent experimental and theoretical investigations of the new nanostructured carbon materials.
Abstract: Interest in hydrogen as a fuel has grown dramatically since 1990, and many advances in hydrogen production and utilization technologies have been made. However, hydrogen storage technologies must be significantly advanced if a hydrogen based energy system, particularly in the transportation sector, is to be established. Hydrogen can be made available on-board vehicles in containers of compressed or liquefied H2, in metal hydrides, via chemical storage or by gas-on-solid adsorption. Although each method possesses desirable characteristics, no approach satisfies all of the efficiency, size, weight, cost and safety requirements for transportation or utility use. Gas-on-solid adsorption is an inherently safe and potentially high energy density hydrogen storage method that could be extremely energy efficient. Consequently, the hydrogen storage properties of high surface area “activated” carbons have been extensively studied. However, activated carbons are ineffective in storing hydrogen because only a small fraction of the pores in the typically wide pore-size distribution are small enough to interact strongly with hydrogen molecules at room temperatures and moderate pressures. Recently, many new carbon nanostructured absorbents have been produced including graphite nanofibers and carbon multi-wall and single-wall nanotubes. The following review provides a brief history of the hydrogen adsorption studies on activated carbons and comments on the recent experimental and theoretical investigations of the hydrogen adsorption properties of the new nanostructured carbon materials.

602 citations


Journal ArticleDOI
TL;DR: In this article, the authors show how reducing structure, catalysis and atomic reactions to the nano-scale may be used in a systematic way to substantially enhance the hydrogenation properties of metal hydrides.
Abstract: We show how reducing structure, catalysis and atomic reactions to the nano-scale may be used in a systematic way to substantially enhance the hydrogenation properties of metal hydrides. We examine, with examples from a wide range of hydrides, the direct impact of nano-scale structure, subsequent improvements in kinetics through nano-scale solid state catalysis, the special properties of nano-composites, and the role played by nano-scale reactions.

562 citations


Journal ArticleDOI
TL;DR: In this paper, a survey of the storage capacities of a large number of different adsorbents for hydrogen at 77 K and 1 bar was presented to examine the feasibility and perspectives of transportable and reversible storage systems based on physisorption of hydrogen on adorbents.
Abstract: A survey is presented of the storage capacities of a large number of different adsorbents for hydrogen at 77 K and 1 bar. Results are evaluated to examine the feasibility and perspectives of transportable and reversible storage systems based on physisorption of hydrogen on adsorbents. It is concluded that microporousadsorbents, e.g. zeolites and activated carbons, display appreciable sorption capacities. Based on their micropore volume (∼1 ml/g) carbon-based sorbents display the largest adsorption, viz. 238 ml (STP)/g, at the prevailing conditions. Optimization of sorbent and adsorption conditions is expected to lead to adsorption of ∼560 ml (STP)/g, close to targets set for mobile applications.

547 citations


Journal ArticleDOI
01 Aug 2001-Carbon
TL;DR: In this paper, theoretical predictions and experimental results on the hydrogen uptake of carbon nanotubes and nanofibers are summarized, and they point out that, in order to accelerate the development of carbon Nanotubes as a practical hydrogen storage medium in fuel cell-driven vehicles, many efforts have to be made to reproduce and verify the results both theoretically and experimentally, and to investigate their volumetric capacity, cycling characteristics and release behavior.

529 citations


Journal ArticleDOI
01 Dec 2001-Carbon
TL;DR: In this paper, the authors studied the hydrogen sorption of nine different carbon materials at pressures up to 11 MPa (1600 psi) and temperatures from −80 to +500°C.

381 citations



Journal ArticleDOI
TL;DR: In this article, the hydrogen storage in purified single-wall carbon nanotubes (SWNTs), graphite and diamond powder was investigated at room temperature and ambient pressure, and the maximum value of overall hydrogen storage was found to be 1.5 wt %, as determined by thermal desorption spectroscopy.
Abstract: The hydrogen storage in purified single-wall carbon nanotubes (SWNTs), graphite and diamond powder was investigated at room temperature and ambient pressure. The samples were sonicated in 5 M HNO3 for various periods of time using an ultrasonic probe of the alloy Ti-6Al-4V. The goal of this treatment was to open the carbon nanotubes. The maximum value of overall hydrogen storage was found to be 1.5 wt %, as determined by thermal desorption spectroscopy. The storage capacity increases with sonication time. The sonication treatment introduces particles of the Ti alloy into the samples, as shown by X-ray diffraction, transmission electron microscopy, and chemical analysis. All of the hydrogen uptake can be explained by the assumption that the hydrogen is only stored in the Ti-alloy particles. The presence of Ti-alloy particles does not allow the determination of whether a small amount of hydrogen possibly is stored in the SWNTs themselves, and the fraction of nanotubes opened by the sonication treatment is unknown.

295 citations


Journal ArticleDOI
TL;DR: In this article, a vibrating-mill technique was used to activate the reaction system by bringing the reagents into very close contact at the preparative scale and by providing extra mechanical energy, much more effectively than the well-known ball-milling method.
Abstract: A vibrating-mill technique, which can activate the reaction system by bringing the reagents into very close contact at the preparative scale and by providing extra mechanical energy, much more effectively than the well-known ball-milling method, was used to prepare titanium(III) chloride (TiCl3·1/3AlCl3)-doped lithium tetrahydridoaluminate (LiAlH4) and lithium hexahydridoaluminate (Li3AlH6) powders with nanocrystallites. The phase structure and dehydriding/rehydriding properties were characterized by using X-ray diffraction (XRD), scanning electron microscopy (SEM), thermogravimetry (TG), and differential scanning calorimetry (DSC). The mechanism of reversible dehydrogenation and rehydrogenation was examined by means of X-ray photoelectron spectroscopy (XPS). Thermodynamic and kinetic measurements showed a distinct change for the dehydriding/rehydriding reactions over the temperature range 25−250 °C. From the Arrhenius plot of hydrogen desorption kinetics, apparent activation energies were found to be 42....

288 citations


Journal ArticleDOI
TL;DR: In this paper, the authors showed that the catalytically enhanced sodium aluminum hydride, NaAlH4, is kinetically enhanced and rendered reversible in the solid state upon doping with selected titanium compounds.
Abstract: The dehydriding of sodium aluminum hydride, NaAlH4, is kinetically enhanced and rendered reversible in the solid state upon doping with selected titanium compounds. Following the initial reports of this catalytic effect, further kinetic improvement and stabilization of the cyclable hydrogen capacity have been achieved upon variation in the method of the introduction of titanium and particle-size reduction. Rapid evolution of 4.0-wt % hydrogen at 100 °C has been consistently achieved for several dehydriding/rehydriding cycles. An improved, 4.8-wt % cyclable capacity has been observed in the material doped with a combination of Ti and Zr alkoxide complexes. Doping the hydride with Ti(OBun)4 and Fe(OEt)2 also produces a synergistic effect, resulting in materials that can be rehydrided to 4 wt % at 104 °C and 87 atm of hydrogen within 17 h. The improved kinetics allowed us to carry out constant-temperature, equilibrium-pressure studies of NaAlH4 that extended to temperatures well below the melting point of the hydride. The 37-kJ/mol value determined for enthalpy of the dehydriding of NaAlH4(s) to Na3AlH6 and Al and the hydrogen plateau pressure of 7 atm at 80 °C are in line with the predictions of earlier studies. The nature of the active catalyst and the mechanism of catalytic action are unknown. The catalytically enhanced hydrides appear to be strong candidates for development as hydrogen carriers for onboard proton exchange membran (PEM) fuel cells. However, further research and development in the areas of rehydriding catalysts, large-scale, long-term cycling, safety and adjustment of the plateau hydrogen pressure associated with dehydriding of AlH6- are required before these materials can be utilized in commercial onboard hydrogen-storage systems.

276 citations


Journal ArticleDOI
TL;DR: In this article, the effect of the chemical nature and stoichiometry of specific alloy families (AB5, A2B, AB/AB2 and AB2) on the hydride stability, hydrogen storage capacity and kinetics of hydrogen sorption-desorption in the solid phase/gas and solid phase-electrolyte solution systems is discussed.
Abstract: Metal hydride electrodes are of particular interest owing to their potential and practical application in batteries. A large number of hydrogen storage materials has been characterized so far. This paper deals with the effect of the chemical nature and stoichiometry of specific alloy families (AB5, A2B, AB/AB2 and AB2) on the hydride stability, hydrogen storage capacity and kinetics of hydrogen sorption-desorption in the solid phase/gas and solid phase/electrolyte solution systems. Special attention has been paid towards the electrochemical properties of metal hydrides in terms of their performance in Ni-MH rechargeable alkaline cells.

Journal ArticleDOI
Abstract: Mechanosynthesis of metal hydrides is a new field in which important progress has been reported. In this paper, we present recent developments in mechanosynthesis of magnesium-based hydrides for storage applications. The effect of intense milling on magnesium and magnesium hydrides is presented. The influence of various additives on hydrogen-sorption properties is discussed with special emphasis on nanocomposite MgH2+5 at. % V, where hydrogen-storage characteristics, cycling properties and the mechanism of hydrogen desorption are presented. The production of novel nanocrystalline porous structures by mechanical alloying followed by a leaching technique is discussed. Hot ball-milling, as a new method for rapid synthesis of alloys, is also presented. Finally, two other methods of production of metal hydrides are discussed. One is reactive milling where metal hydrides are synthesized by mechanical alloying under hydrogen pressure, while the other is milling elemental hydrides to produce complex hydrides.

Journal ArticleDOI
TL;DR: The authors' calculations describe suitably an electrochemical storage process of hydrogen, which is applicable for the secondary hydrogen battery, and the hydrogen-adsorption and -storage mechanism in carbon nanotubes at zero temperature.
Abstract: We have carried out systematic calculations for hydrogen-adsorption and -storage mechanism in carbon nanotubes at zero temperature. Hydrogen atoms first adsorb on the tube wall in an arch-type and zigzag-type up to a coverage of θ = 1.0 and are stored in the capillary as a form of H2 molecule at higher coverages. Hydrogen atoms can be stored dominantly through the tube wall by breaking the C−C midbond, while preserving the wall stability of a nanotube after complete hydrogen insertion, rather than by the capillarity effect through the ends of nanotubes. In the hydrogen-extraction processes, H2 molecule in the capillary of nanotubes first dissociates and adsorbs onto the inner wall and is further extracted to the outer wall by the flip-out mechanism. Our calculations describe suitably an electrochemical storage process of hydrogen, which is applicable for the secondary hydrogen battery.

Journal ArticleDOI
TL;DR: In this article, an integrated renewable energy (RE) system for powering remote communication stations and based on hydrogen is described, whereby the electricity is generated by a 10 kW wind turbine and 1 kW photovoltaic (PV) array.

Journal ArticleDOI
TL;DR: In this paper, the authors present some recent results on the electrochemical behavior of metal hydride batteries and the mechanisms of the hydrogen evolution reaction (h.r.) taking place.

Journal ArticleDOI
TL;DR: In this paper, two desorption peaks of hydrogen molecule (mass number = 2) starting at about 600 and 950 K, respectively, are observed for nanostructured graphite mechanically milled for 80 h under hydrogen atmosphere.
Abstract: Two desorption peaks of hydrogen molecule (mass number=2), starting at about 600 and 950 K, respectively, are observed in thermal desorption mass spectroscopy of nanostructured graphite mechanically milled for 80 h under hydrogen atmosphere. It follows from a combined analysis of thermal desorption mass spectroscopy and thermogravimetry, that ∼6 mass % of hydrogen (corresponding to 80% of the total amount of hydrogen) is desorbed at the first desorption peak as a mixture of pure hydrogen and hydrocarbons. Below the temperature of the second desorption peak, at which recrystallization related desorption occurs, nanostructured graphite is expected to retain its specific defective structures mainly with carbon dangling bonds as suitable trapping sites for hydrogen storage. The formation process of the nanostructures during milling under hydrogen atmosphere is also discussed on the basis of the profile of Raman spectroscopy.

Journal ArticleDOI
TL;DR: In this article, the structural and desorption properties of MgH2 were examined by X-ray diffraction (XRD), differential scanning calorimetry (DSC), thermogravimetric analysis (TG), and scanning electron microscopy (SEM).

Journal ArticleDOI
TL;DR: Although the alkalimetal-doped carbon nanotubes showed high H2 weight uptake, further investigations indicated that some of this uptake was due to water rather than hydrogen, which indicates a potential source of error in evaluation of the storage capacity of doped carbon Nanotubes.
Abstract: Recent progress in the production, purification, and experimental and theoretical investigations of carbon nanotubes for hydrogen storage are reviewed. From the industrial point of view, the chemical vapor deposition process has shown advantages over laser ablation and electric-arc-discharge methods. The ultimate goal in nanotube synthesis should be to gain control over geometrical aspects of nanotubes, such as location and orientation, and the atomic structure of nanotubes, including helicity and diameter. There is currently no effective and simple purification procedure that fulfills all requirements for processing carbon nanotubes. Purification is still the bottleneck for technical applications, especially where large amounts of material are required. Although the alkalimetal-doped carbon nanotubes showed high H2 weight uptake, further investigations indicated that some of this uptake was due to water rather than hydrogen. This discovery indicates a potential source of error in evaluation of the storage capacity of doped carbon nanotubes. Nevertheless, currently available single-wall nanotubes yield a hydrogen uptake value near 4 wt% under moderate pressure and room temperature. A further 50% increase is needed to meet U.S. Department of Energy targets for commercial exploitation. Meeting this target will require combining experimental and theoretical efforts to achieve a full understanding of the adsorption process, so that the uptake can be rationally optimized to commercially attractive levels. Large-scale production and purification of carbon nanotubes and remarkable improvement of H2 storage capacity in carbon nanotubes represent significant technological and theoretical challenges in the years to come.

Journal ArticleDOI
TL;DR: A newly developed technique reported in this article that allows one to significantly improve the thermal conductivity of a metal hydride, LaNi5, is presented and compacts with recompressed expanded graphite were made and their thermal conductivities measurements were taken.

Journal ArticleDOI
TL;DR: In this article, the authors review the existing theoretical literature on hydrogen storage in single-walled nanotubes and carbon nanofibers and suggest that a variety of complex chemical processes could accompany hydrogen storage and release.
Abstract: In this paper we review the existing theoretical literature on hydrogen storage in single-walled nanotubes and carbon nanofibers. The reported calculations indicate a hydrogen uptake smaller than some of the more optimistic experimental results. Furthermore the calculations suggest that a variety of complex chemical processes could accompany hydrogen storage and release.

Journal ArticleDOI
TL;DR: The previously unexplained experimental observations of the direct hydrogenation of fullerenes under high pressure lend further support for a mechanism for the dissociative chemisorption of H2 on carbon nanotubes.
Abstract: Based on first principles calculations, we propose a mechanism for the dissociative chemisorption of H2 on carbon nanotubes. The breaking of the H—H bond is concerted with the formation of two C—H bonds on two adjacent carbon nanotubes in solid phase, facilitated by the application of high pressure which shortens the interstitial distance between nanotubes. The process is reversible upon the release of external pressure and could make an important contribution to the observed hydrogen storage capacity of carbon nanotubes. The previously unexplained experimental observations of the direct hydrogenation of fullerenes under high pressure lend further support for such a mechanism.

Journal ArticleDOI
TL;DR: In this article, the results of a parametric and comparative study of adsorption and compressed gas storage of hydrogen as a function of temperature, pressure and adsorbent properties are compared and discussed.

Journal ArticleDOI
TL;DR: In this paper, aligned carbon nanotubes (CNTs) with diameters of 50-100 nm were employed for hydrogen adsorption experiments in their as-prepared and pretreated states.
Abstract: Aligned carbon nanotubes (CNTs) with diameters of 50–100 nm, synthesized by plasma-assisted hot filament chemical vapor deposition, were employed for hydrogen adsorption experiments in their as-prepared and pretreated states. Quadruple mass spectroscopy and thermogravimetric analysis show a hydrogen storage capacity of 5–7 wt% was achieved reproducibly at room temperature under modest pressure (10 atm) for the as-prepared samples. Pretreatments, which include heating the samples to 300 °C and removing of the catalyst tips, can increase the hydrogen storage capacity up to 13 wt% and decrease the pressure required for storage. The weight gains were measured after the samples moved out of the hydrogen environment. The release of the adsorbed hydrogen can be achieved by heating the samples up to 300 °C.

Journal ArticleDOI
TL;DR: In this article, Bogdanovic et al. used a simple way by hydrogenation of aluminum powder in conjunction with sodium hydride in the presence of Ti(OBun)4 (Bun= n-C4Hg) as a dopant.
Abstract: Ti-doped NaAlH4 can be prepared in a simple way by hydrogenation of aluminum powder in conjunction with sodium hydride in the presence of Ti(OBun)4 (Bun= n-C4Hg) as a dopant. After a few hydrogenation/dehydrogenation cycles the material reaches a storage capacity of ∼4 wt %H2 and exhibits reaction rates comparable to or exceeding those previously found for NaAlH4 doped with Ti(OBun)4 in organic solvents [Bogdanovic et al.: J. Alloys Compd. 302, 36 (2000)].

Patent
28 Sep 2001
TL;DR: In this paper, the authors present an exemplary embodiment of the regenerative electrochemical cell system, which comprises a fuel cell module (12) comprising a fuel-cell oxygen inlet in fluid communication a water storage device (28), and a fuelcell hydrogen inlet with both an oxygen source and with a gaseous portion of an water phase separation device.
Abstract: An exemplary embodiment of the regenerative electrochemical cell system comprises: a fuel cell module (12) comprising a fuel cell oxygen inlet in fluid communication a water storage device (28), and a fuel cell hydrogen inlet in fluid communication with both an oxygen source and with a gaseous portion of an water phase separation device; an electrolysis module (10) comprising an electrolysis water inlet in fluid communication with the water storage device via a fuel cell oxygen outlet, and an electrolysis water outlet in fluid communication with the fuel cell hydrogen. One of the embodiments for operating a regenerative electrochemical cell system disclosed herein, comprises: introducing feed hydrogen from a hydrogen storage system (14) to a fuel hydrogen electrode and introducing feed oxygen from an oxygen/water phase separation device (66) to a fuel cell oxygen electrode; reacting hydrogen ions with the oxygen to generate electricity and water; once the fuel cell has attained operating conditions, ceasing the feed oxygen from the oxygen/water phase separation device, and introducing second oxygen from a surrounding atmosphere module to the fuel cell oxygen electrode, directing the water to a water storage device; introducing water to an electrolysis water electrode and power to an electrolysis module, to produce refuel hydrogen and oxygen; and directing the refuel hydrogen to the hydrogen storage device.

Journal ArticleDOI
TL;DR: In this article, mechanical milling of the La and Ni powder blend results in the direct formation of nanocrystalline AB5 phase, and hydrogen storage measurements show that this as-milled LaNi5 compound does not absorb much hydrogen reversibly.

Journal ArticleDOI
TL;DR: RodRodriguez, Baker and co-workers as discussed by the authors have reported uptake of hydrogen in graphitic nanofibres (GNFs) of 40% by weight, if these results are confirmed, then this class of material could be a suitable storage medium for hydrogen for use in fuel cell vehicles.
Abstract: Rodriguez, Baker and co-workers (A. Chambers, C. Park, R. T. K. Baker and N. M. Rodriguez, J. Phys. Chem. B, 1998, 102, 4253; C. Park, C. D. Tan, R. Hidalgo, R. T. K. Baker and N. M. Rodriguez, Proc. 1998 US DOE Hydrogen Program Reiew, (http://www.eren.doe.gov/hydrogen/docs/25315toc.html); C. Park, P. E. Anderson, A. Chambers, C. D. Tan, R. Hidalgo and N. M. Rodriguez, J. Phys. Chem. B, 1999, 103, 10572) have reported uptake of hydrogen in graphitic nanofibres (GNFs) of 40% by weight. If these results are confirmed, then this class of material could be a suitable storage medium for hydrogen for use in fuel cell vehicles. In order to test whether these results are feasible, we report results for grand canonical Monte Carlo simulation of hydrogen adsorption in graphitic pores. A classical technique was employed but the results obtained were shown to be consistent with previous path integral Monte Carlo calculations of Wang and Johnson (Q. Wang and J. K. Johnson, J. Chem. Phys., 1999, 110, 577; Q. Wang and J. K. Johnson, J. Phys. Chem. B, 1999, 103, 277). The interaction between hydrogen and the graphitic surface was modelled initially by dispersion forces. The predicted uptake (up to 1.5%) was much lower than the Baker–Rodriguez results. The results were found to be fairly insensitive as to whether the hydrogen molecule was modelled as a Lennard-Jones sphere or a dumbbell fluid with two Lennard-Jones sites. Two models for a hypothetical potential for chemisorption were also used in the simulation. The potential was based on calculation of the interaction between atomic hydrogen and a graphitic surface. Adsorption of up to 17 wt.% was measured with the stronger model potential but there was negligible desorption at ambient pressure, making it impractical. A more plausible, though still hypothetical, potential gave loadings of up to 8 wt.% in the model system. These results are still much lower than the Baker–Rodriguez data in spite of the fact that there is no evidence to suggest that chemisorption actually occurs in a real system.

Patent
27 Apr 2001
TL;DR: In this paper, a system and method for the storage of electrical energy or of hydrogen is described, which includes the steps of electrolysis of water to yield hydrogen, reaction of the hydrogen from step (a) with carbon dioxide to from at least one storage compound, storage of the storage compound; and subsequent conversion of the stored compound back to hydrogen or use of storage compound to fuel an engine, such as an internal combustion engine, or to generate electricity directly or indirectly.
Abstract: A system and method for the storage of electrical energy or of hydrogen, the method includes the steps of (a) electrolysis of water to yield hydrogen, (b) reaction of the hydrogen from step (a) with carbon dioxide to from at least one storage compound; (c) storage of the storage compound; and (d) subsequent conversion of the storage compound back to hydrogen or use of the storage compound to fuel an engine, such as an internal combustion engine, or to generate electricity directly or indirectly One storage compound is methanol

Journal ArticleDOI
TL;DR: The effects of hydrogen on various metals and the use of metal hydrides for hydrogen storage are discussed in this article, where the mechanisms of hydrogen embrittlement and hydrogen attack of ferritic steels are compared, common sources of hydrogen in metals processing and treatment identified, and mechanisms for hydrogen entry into a ferritic surface are discussed.

Journal ArticleDOI
Yuchen Ma1, Yueyuan Xia1, Mingwen Zhao1, Ruijin Wang1, Liangmo Mei1 
TL;DR: In this paper, the hydrogen storage behavior of single-wall carbon nanotubes was studied using molecular dynamics simulations and ab initio electronic calculations, and the density of injected hydrogen in the tube and the pressure on the wall of the nanotube induced by the stored hydrogen molecules were evaluated.
Abstract: The hydrogen-storage behavior of single-wall carbon nanotubes was studied using molecular dynamics simulations and ab initio electronic calculations. Hydrogen atoms with kinetic energy of 16--25 eV were observed to penetrate into and be trapped inside the tube. Consecutively injected H atoms form hydrogen molecules, and gradually condense to become liquid hydrogen in the tube. The density of injected hydrogen in the tube and the pressure on the wall of the nanotube induced by the stored hydrogen molecules were evaluated at room temperature.