Showing papers on "Hydrogen storage published in 2007"
TL;DR: A review of metal hydrides on properties including hydrogen-storage capacity, kinetics, cyclic behavior, toxicity, pressure and thermal response is presented in this article, where a group of Mg-based hydride stand as promising candidate for competitive hydrogen storage with reversible hydrogen capacity up to 7.6 W% for on-board applications.
2,890 citations
TL;DR: In this paper, the stability of graphane was predicted based on first-principles total energy calculations, which is a fully saturated two-dimensional hydrocarbon derived from a single graphene sheet with formula CH.
Abstract: We predict the stability of an extended two-dimensional hydrocarbon on the basis of first-principles total-energy calculations. The compound that we call graphane is a fully saturated hydrocarbon derived from a single graphene sheet with formula CH. All of the carbon atoms are in $s{p}^{3}$ hybridization forming a hexagonal network and the hydrogen atoms are bonded to carbon on both sides of the plane in an alternating manner. Graphane is predicted to be stable with a binding energy comparable to other hydrocarbons such as benzene, cyclohexane, and polyethylene. We discuss possible routes for synthesizing graphane and potential applications as a hydrogen storage material and in two-dimensional electronics.
1,758 citations
TL;DR: The air-free compound exhibits the highest gravimetric and volumetric H2 uptake capacities yet demonstrated for a cryogenic hydrogen storage material and no loss of capacity was apparent during 24 complete adsorption−desorpti...
Abstract: The prototypical metal-organic framework Zn4O(BDC)3 (MOF-5, BDC2- = 1,4-benzenedicarboxylate) decomposes gradually in humid air to form a nonporous solid. Recognizing this, improved procedures for its synthesis and handling were developed, leading to significant increases in N2 and H2 gas adsorption capacities. Nitrogen adsorption isotherms measured at 77 K reveal an enhanced maximum N2 uptake of 44.5 mmol/g and a BET surface area of 3800 m2/g, compared to the 35.8 mmol/g and 3100 m2/g obtained for a sample prepared using previous methods. High-pressure H2 adsorption isotherms show improvements from 5.0 to 7.1 excess wt % at 77 K and 40 bar. The total H2 uptake was further observed to climb to 11.5 wt % at 170 bar, corresponding to a volumetric storage density of 77 g/L. Thus, the air-free compound exhibits the highest gravimetric and volumetric H2 uptake capacities yet demonstrated for a cryogenic hydrogen storage material. Moreover, no loss of capacity was apparent during 24 complete adsorption−desorpti...
1,465 citations
TL;DR: In this article, the current status of vehicular hydrogen storage is reviewed and research associated with the National Hydrogen Storage Project is discussed, and future plans through the International Partnership for the Hydrogen Economy (IPHE) are also presented.
968 citations
TL;DR: Current progress in catalysis research to control the rate and extent of hydrogen release and preliminary efforts at regeneration of H3NBH3 are discussed.
Abstract: Ammonia–borane, H3NBH3, is an intriguing molecule for chemical hydrogen storage applications. With both protic N–H and hydridic B–H bonds, three H atoms per main group element, and a low molecular weight, H3NBH3 has the potential to meet the stringent gravimetric and volumetric hydrogen storage capacity targets needed for transportation applications. Furthermore, devising an energy-efficient chemical process to regenerate H3NBH3 from dehydrogenated BNHx material is an important step towards realization of a sustainable transportation fuel. In this perspective we discuss current progress in catalysis research to control the rate and extent of hydrogen release and preliminary efforts at regeneration of H3NBH3.
911 citations
TL;DR: The particle size dependence of insertion reactions has been investigated for lithiated anatase TiO2, revealing progressively increasing Li capacity and Li-ion solubility for decreasing particle sizes, strongly deviating from the expected Li-rich andLi-poor phase separation as occurs in the bulk material.
Abstract: Insertion reactions are of key importance for Li ion and hydrogen storage materials and energy storage devices. The particle size dependence of insertion reactions has been investigated for lithiated anatase TiO2, revealing progressively increasing Li capacity and Li-ion solubility for decreasing particle sizes, strongly deviating from the expected Li-rich and Li-poor phase separation as occurs in the bulk material. The phase diagram alters significantly, changing the materials properties already at sizes as large as 40 nm. A rationale is found in the surface strain that occurs between the different intercalated phases, which becomes energetically too costly in small particles. In particular the observed particle size-induced solid solution behavior is expected to have fundamental and practical implications for two-phase lithium or hydrogen insertion reactions.
682 citations
TL;DR: For any potential hydrogen storage system, raw uptake capacity must be balanced with the kinetics and thermodynamics of uptake and release as discussed by the authors, and metal-organic frameworks (MOFs) provide unique systems with large overall pore volumes and surface areas, adjustable pore sizes, and tunable framework-adsorbate interaction by ligand functionalization and metal choice.
Abstract: For any potential hydrogen-storage system, raw uptake capacity must be balanced with the kinetics and thermodynamics of uptake and release. Metal–organic frameworks (MOFs) provide unique systems with large overall pore volumes and surface areas, adjustable pore sizes, and tunable framework–adsorbate interaction by ligand functionalization and metal choice. These remarkable materials can potentially fill the niche between other physisorbents such as activated carbon, which have similar uptake at low temperatures but low affinity for hydrogen at ambient temperature, and chemical sorbents such as hydrides, which have high hydrogen uptakes but undesirable release kinetics and thermodynamics.
670 citations
631 citations
TL;DR: The first example of a homogeneous first row transition-metal-based catalyst which is active for dehydrogenation of ammonia−borane, H3NBH3, a promising chemical hydrogen storage material is reported, suggesting both N−H and B−H bonds are being broken in the rate-determining step(s).
Abstract: We report here the first example of a homogeneous first row transition-metal-based catalyst which is active for dehydrogenation of ammonia−borane, H3NBH3, a promising chemical hydrogen storage material. Addition of ammonia−borane to an active catalyst formed in situ from the reaction of Ni(cod)2 and 2 equiv of an appropriate N-heterocyclic carbene (NHC) rapidly evolves hydrogen at 60 °C. Using a gas burette to quantify the gas evolved, 29 of a possible 31 mL of H2 for 3 equiv of H2 was produced, equating to >2.5 equiv of H2 from ammonia−borane. Kinetic isotope effects of deuterated derivatives of ammonia−borane suggest that both N−H and B−H bonds are being broken in the rate-determining step(s).
608 citations
583 citations
TL;DR: In this paper, a review summarizes the effects that nanotechnology can have on the main properties of metal hydrides and highlights the main competing behaviours between the system requirements, the necessary trade-offs, and the research priorities necessary to obtain hydride storage materials for practical automotive applications.
Abstract: Hydrogen is considered a good energy carrier candidate for future automotive applications that could be part of a carbon-free cycle. Metal hydrides are often preferred over pressurized gas and other hydrogen storage methods because of their gravimetric and volumetric storage capacities and safe operating pressures. In addition to the hydrogen storage capacity, other properties that have often been disregarded must now be addressed before hydrogen storage in metal hydrides becomes feasible. The slow hydriding/dehydriding kinetics, high release temperature, low storage efficiency due to the high enthalpy of formation, and thermal management during the hydriding reaction remain important difficulties in meeting the objectives set by the Department of Energy (DOE) for hydrogen storage systems. Nanotechnology offers new ways of addressing those issues by taking advantage of the distinctive chemical and physical properties observed in nanostructures. Nanostructured materials significantly improve the reaction kinetics, reduce the enthalpy of formation, and lower the hydrogen absorption and release temperatures through destabilization of the metal hydride and multiple catalytic effects in the system. But nanostructures can also lead to poor cyclability, degradation of the sorption properties, and a significant reduction of the thermal conductivity that could make metal hydrides impractical for hydrogen storage. This review summarizes the effects that nanotechnology can have on the main properties of metal hydrides and highlights the main competing behaviours between the system requirements, the necessary trade-offs, and the research priorities necessary to obtain hydride storage materials for practical automotive applications. Copyright © 2007 John Wiley & Sons, Ltd.
TL;DR: The hydrogen uptake capacity observed for the zeolite-like carbon materials is among the highest ever reported for carbon (activated carbon, mesoporous carbon, CNTs) or any other (MOFs, zeolites) porous material.
Abstract: We report the synthesis of zeolite-like carbon materials that exhibit well-resolved powder XRD patterns and very high surface area. The zeolite-like carbons are prepared via chemical vapor deposition (CVD) at 800 or 850 °C using zeolite β as solid template and acetonitrile as carbon precursor. The zeolite-like structural ordering of the carbon materials is indicated by powder XRD patterns with at least two well-resolved diffraction peaks and TEM images that reveal well-ordered micropore channels. The carbons possess surface area of up to 3200 m2/g and pore volume of up to 2.41 cm3/g. A significant proportion of the porosity in the carbons (up to 76% and 56% for surface area and pore volume, respectively) is from micropores. Both TEM and nitrogen sorption data indicate that porosity is dominated by pores of size 0.6−0.8 nm. The carbon materials exhibit enhanced (and reversible) hydrogen storage capacity, with measured uptake of up to 6.9 wt % and estimated maximum of 8.33 wt % at −196 °C and 20 bar. At 1 b...
TL;DR: The results suggested that MOF-177 could be a potentially promising material for gas separation and storage applications at ambient temperature (under dry conditions or with predrying).
Abstract: Gas adsorption experiments have been carried out on a zinc benzenetribenzoate metal−organic framework material, MOF-177. Hydrogen adsorption on MOF-177 at 298 K and 10 MPa gives an adsorption capacity of ∼0.62 wt %, which is among the highest hydrogen storage capacities reported in porous materials at ambient temperatures. The heats of adsorption for H2 on MOF-177 were −11.3 to −5.8 kJ/mol. By adding a H2 dissociating catalyst and using our bridge building technique to build carbon bridges for hydrogen spillover, the hydrogen adsorption capacity in MOF-177 was enhanced by a factor of ∼2.5, to 1.5 wt % at 298 K and 10 MPa, and the adsorption was reversible. N2 and O2 adsorption measurements showed that O2 was adsorbed more favorably than N2 on MOF-177 with a selectivity of ∼1.8 at 1 atm and 298 K, which makes MOF-177 a promising candidate for air separation. The isotherm was linear for O2 while being concave for N2. Water vapor adsorption studies indicated that MOF-177 adsorbed up to ∼10 wt % H2O at 298 K....
TL;DR: In this article, the results available for adsorption of hydrogen on porous materials, ranging from activated carbons to metal organic framework materials, are discussed, and it is shown that up to 5 and 7.5% of hydrogen can be stored on porous carbon and metal organic frameworks, respectively, at 77 K.
TL;DR: Palladium was infiltrated into the highly porous metal-organic framework MOF-5 using [Pd(acac)2] (acac = acetylacetonate) as the precursor in chloroform solution viaipient wetness impregnation.
Abstract: Palladium was infiltrated into the highly porous metal–organic framework MOF-5 {[Zn4O(bdc)3], bdc = benzene-1,4-dicarboxylate} using [Pd(acac)2] (acac = acetylacetonate) as the precursor in chloroform solution via
‘incipient wetness’ impregnation. The specific surface area decreases from 2885 m2 g−1 to 958 m2 g−1 after infiltration. After reduction in hydrogen or under vacuum, the hydrogen adsorption capacity is increased from 1.15 wt% to 1.86 wt% at 1 atm and 77 K. The palladium loaded MOF-5 has a high catalytic activity in styrene hydrogenation comparable to that of palladium on activated carbon, but cis-cyclooctene hydrogenation is considerably slower. Even at room temperature, the catalyst is not stable in air due to the low hydrothermal stability of the MOF-5 support.
TL;DR: The combination of different storage systems may provide a possible solution to store sufficiently high amounts of hydrogen in order to fulfil the requirements for a broad introduction of automotive fuel cell powertrains to the market.
Abstract: To ensure future worldwide mobility, hydrogen storage in combination with fuel cells for on-board automotive applications is one of the most challenging issues. Potential solid-state solutions have to fulfil operating requirements defined by the fuel cell propulsion system. Important requirements are also defined by customer demands such as cost, overall fuel capacity, refuelling time and efficiency. It seems that currently none of the different storage solid state materials can reach the required storage densities for a hydrogen-powered vehicle. New strategies for storage systems are necessary to fulfil the requirements for a broad introduction of automotive fuel cell powertrains to the market. The combination of different storage systems may provide a possible solution to store sufficiently high amounts of hydrogen.
TL;DR: In this paper, the authors summarized the recent developments concerning sorption properties and thermodynamics of Mg-based hydrides for hydrogen storage applications in particular, promising strategies to decrease the hydrogen reaction enthalpy by alloying and the use of reactive hydride composites are discussed.
TL;DR: In this paper, a useful interpretation of the hydrogen adsorption data according to the porosity of the materials and to the adaption conditions, using the fundamentals of adsorptions, is provided.
TL;DR: Surprisingly, the two strongest adsorption sites that the authors identified are both directly associated with the organic linkers, instead of the ZnN4 clusters, in strong contrast to classical MOFs, where the metal-oxide clusters are the primary adsorptive sites.
Abstract: Using the difference Fourier analysis of neutron powder diffraction data along with first-principles calculations, we reveal detailed structural information such as methyl group orientation, hydrogen adsorption sites, and binding energies within the nanopore structure of ZIF8 (Zn(MeIM)2). Surprisingly, the two strongest adsorption sites that we identified are both directly associated with the organic linkers, instead of the ZnN4 clusters, in strong contrast to classical MOFs, where the metal-oxide clusters are the primary adsorption sites. These observations are important and hold the key to optimizing this new class of ZIF materials for practical hydrogen storage applications. Finally, at high concentration H2-loadings, ZIF8 structure is capable of holding up to 28 H2 molecules (i.e., 4.2 wt %) in the form of highly symmetric novel three-dimensional interlinked H2-nanoclusters with relatively short H2−H2 distances compared to solid H2. Hence, ZIF compounds with robust chemical stability can be also an id...
TL;DR: In this paper, the authors provide a framework for describing the permeability, solubility and diffusivity of hydrogen and its isotopes in austenitic stainless steels at temperatures and high gas pressures of interest for hydrogen storage and distribution infrastructure.
TL;DR: Theoretical Developments 4147 - Extensions of van der Waals−Platteeuw Theory 4147 4.1.2.
Abstract: 3. Experimental Probes 4142 3.1. Neutron Scattering 4142 3.1.1. Structure 4142 3.1.2. Phonon Density of States 4143 3.2. Raman Scattering 4144 3.2.1. Internal ModessCrystal Field 4144 3.2.2. Rotational and Translational Modes 4145 3.3. Nuclear Magnetic Resonance 4145 3.4. Thermal Conductivity and Heat Capacity 4146 4. Theoretical Developments 4147 4.1. Semiempirical Models 4147 4.1.1. Extensions of van der Waals−Platteeuw Theory 4147
TL;DR: A detailed analysis of the reaction mechanism of the reactive hydride composite (RHC) was performed using high-pressure differential scanning calorimetry (HP-DSC) measurements and in situ synchrotron powder X-ray diffraction (XRD) measurements along with kinetic investigations using a Sievert-type apparatus as discussed by the authors.
TL;DR: A mechanistic model for the induction, nucleation and growth for AB decomposition leading to formation of hydrogen is proposed, which yields a mobile phase of AB caused by disruption of the dihydrogen bonds and nucleation that yields reactive DADB from the mobile AB.
Abstract: The mechanism of hydrogen release from solid state ammonia borane (AB) has been investigated via in situ solid state 11B and 11B{1H} MAS-NMR techniques in external fields of 7.1 T and 18.8 T at a decomposition temperature of 88 °C, well below the reported melting point. The decomposition of AB is well described by an induction, nucleation and growth mechanistic pathway. During the induction period, little hydrogen is released from AB; however, a new species identified as a mobile phase of AB is observed in the 11B NMR spectra. Subsequent to induction, at reaction times when hydrogen is initially being released, three additional species are observed: the diammoniate of diborane (DADB), [(NH3)2BH2]+[BH4]−, and two BH2N2 species believed to be the linear (NH3BH2NH2BH3) and cyclic dimer (NH2BH2)2 of aminoborane. At longer reaction times the sharper features are replaced by broad, structureless peaks of a complex polymeric aminoborane (PAB) containing both BH2N2 and BHN3 species. The following mechanistic model for the induction, nucleation and growth for AB decomposition leading to formation of hydrogen is proposed: (i) an induction period that yields a mobile phase of AB caused by disruption of the dihydrogen bonds; (ii) nucleation that yields reactive DADB from the mobile AB; and (iii) growth that includes a bimolecular reaction between DADB and AB to release the stored hydrogen.
TL;DR: The present results indicate that NH3BH3 along with Ni1-xPtx alloy hollow spheres may find some applications for small-scale on-board hydrogen storage and supply.
Abstract: In this paper, nest-like Ni1-xPtx (x = 0, 0.03, 0.06, 0.09, and 0.12) hollow spheres of submicrometer sizes have been prepared through a template-replacement route and investigated as catalysts for generating hydrogen from ammonia borane (NH3BH3). Experimental investigations have demonstrated that the obtained Ni1-xPtx alloy hollow spheres exhibit favorable catalytic activities for both the hydrolysis and the thermolysis of NH3BH3. It was found that, in the presence of the Ni0.88Pt0.12 catalyst, the hydrolysis of NH3BH3 causes a quick release of H2, while the thermal decomposition of NH3BH3 occurs at lowered temperatures with increased mass loss. The present results indicate that NH3BH3 along with Ni1-xPtx alloy hollow spheres may find some applications for small-scale on-board hydrogen storage and supply.
TL;DR: In this paper, the authors describe approaches for modifying the thermodynamics and kinetics of hydrogen sorption reactions in light-metal hydrides using additives that form new compounds during dehydrogenation.
TL;DR: In this article, the pore characteristics and gas sorption properties of two microporous metal-organic framework structures, [M(bdc)(ted)0.5]·2DMF-0.2H 2 O (M=Zn (1), Cu (2); H2bdc=1,4-benzenedicarboxylic acid; ted=triethylenediamine; DMF: N,N-dimethylformamide) is reported.
Abstract: The design, synthesis, and structural characterization of two microporous metal-organic framework structures, [M(bdc)(ted)0.5]·2DMF-0.2H 2 O (M=Zn (1), Cu (2); H2bdc=1,4-benzenedicarboxylic acid; ted=triethylenediamine; DMF: N,N-dimethylformamide) is reported. The pore characteristics and gas sorption properties of these compounds are investigated at cryogenic temperatures, room temperature, and higher temperatures by experimentally measuring argon, hydrogen, and selected hydrocarbon adsorption/desorption isotherms. These studies show that both compounds are highly porous with a pore volume of 0.65 (1) and 0.52 cm 3 g -1 (2). The amount of the hydrogen uptake, 2.1 wt % (1) and 1.8 wt % (2) at 77 K (1 atm; 1 atm =101 325 Pa), places them among the group of metal-organic frameworks (MOFs) having the highest H 2 sorption capacity. [Zn(bdc)(ted) 0.5 ]·2 DMF·0.2 H 2 O adsorbs a very large amount of hydrocarbons, including methanol, ethanol, dimethylether (DME), n-hexane, cyclohexane, and benzene, giving the highest sorption values among all metal-organic based porous materials reported to date. In addition, these materials hold great promise for gas separation.
TL;DR: In this paper, several ways to synthesize solvated and desolvated magnesium tetrahydroborate by wet chemical and mechanochemical methods were tested and compared.
Abstract: Mg(BH4)2 is one of the few complex hydrides which have the potential to meet the requirements for hydrogen storage materials, because it contains 14.9 mass% H and has suitable thermodynamic properties. It has not been investigated for hydrogen storage applications yet. In this study, several ways to synthesize solvated and desolvated magnesium tetrahydroborate by wet chemical and mechanochemical methods were tested and compared. A direct synthesis by a reaction of MgH2 with aminoboranes yields magnesium tetrahydroborate quantitatively and in pure form. The method is also applicable to the synthesis of other tetrahydroborates. The products were characterized by elemental analysis, in situ X-ray diffraction (XRD), infrared spectroscopy (FTIR), and thermal analysis methods, such as thermogravimetric analysis (TGA-DSC) and high-pressure calorimetry under a hydrogen atmosphere (HP-DSC).
TL;DR: The tetrahydroborates represent a class of complex hydrides with the largest gravimetric and volumetric hydrogen density for hydrogen as discussed by the authors, and they are potential hydrogen storage materials for mobile applications.