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‣ Modificação superficial de ligas armazenadoras de hidrogênio por óxidos metálicos a partir do método sol-gel; Surface modification on hydrogen storage alloys by metal oxides via sol-gel route

Bocutti, Rosangela
Fonte: Biblioteca Digitais de Teses e Dissertações da USP Publicador: Biblioteca Digitais de Teses e Dissertações da USP
Tipo: Dissertação de Mestrado Formato: application/pdf
Publicado em 26/05/2003 Português
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Este trabalho consiste na análise da modificação superficial da liga armazenadora de hidrogênio, MmNi3,4Co0,8Al0,8, através de óxidos de Cobre, Níquel e Cobalto, utilizando-se para tanto o método sol-gel. As técnicas de caracterização usadas para o recobrimento obtido, Microscopia Eletrônica de Varredura (MEV) e Redução Térmica Programada (RTP), permitiram a observação de uma "rede" formada pelos óxidos presentes nos recobrimentos que proporcionam a aglomeração das partículas da liga, sem contudo, impedir a interação de hidrogênio com o material. O estudo do comportamento eletroquímico do recobrimento foi realizado pelas técnicas de Voltametria Cíclica , Ciclos Galvanostáticos de Carga e Descarga e Espectroscopia de Impedância. Foi possível verificar que a camada de óxidos formada pelo recobrimento através do método sol-gel melhora o desempenho da liga: em relação a sua capacidade de descarga que é significativamente aumentada, principalmente no recobrimento por óxido de cobalto e também em relação a proteção contra a pulverização do material, que proporciona maiores números de ciclos de carga e descarga; This work consists in the analysis of the surface modification of the hydrogen storage alloy...

‣ Metallic hydrides: a hydrogen storage option?

Rangel, C. M.; Fernandes, Vitor R.
Fonte: Laboratório Nacional de Energia e Geologia Publicador: Laboratório Nacional de Energia e Geologia
Tipo: Conferência ou Objeto de Conferência
Publicado em 09/05/2008 Português
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The development of a safe and efficient way to store hydrogen that may exhibit good gravimetric and volumetric efficiencies is considered instrumental to hydrogen utilization as an alternative to fossil fuels. Furthermore, cost, safety and ease of production must be considered when evaluating storage options. Currently, no available system satisfies the requirements for wide scale acceptance. Some metallic systems allow reversible absorption/desorption of hydrogen, at temperatures and pressures suitable for practical applications. Currently, metallic hydrides based on intermetallic alloys are the most studied storage options for applications where weight is not an issue, representing more compact systems (by factor of 3x) when compared with high pressure compressed gas. In this work, the general mechanism of hydrogenation of metallic systems is discussed highlighting the potential for improvements and limitations. Examples of AB5 and AB type intermetallics will be given.

‣ Metal hydrides for hydrogen storage at low charging pressures

Fernades, Vitor R.; Peñalosa, J.; Rangel, C. M.
Fonte: Laboratório Nacional de Energia e Geologia Publicador: Laboratório Nacional de Energia e Geologia
Tipo: Conferência ou Objeto de Conferência
Publicado em 15/02/2008 Português
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LaNi5 alloys are been extensively study as hydrogen storage material due their easy activation and good kinetics. LaNi5 alloys, containing substitutional elements such as Al or Ce, allow adjustments of the equilibrium pressure and absorption kinetics of the metallic hydrides making them storage candidate materials susceptible to be used in fuel cells systems. In this work, the thermodynamic properties of LaNi5-yAly and LaNi5, La1-xCexNi5 alloys were evaluated using a purpose built Sievert-type apparatus.

‣ Synthesis of FeTi hydrogen storage material via ball milling: effect of milling energy and atmosphere.

Livramento, Vanessa; Rangel, C. M.; Correia, J. Brito; Shohoji, Nobumitsu; Silva, R. A.
Fonte: Laboratório Nacional de Energia e Geologia Publicador: Laboratório Nacional de Energia e Geologia
Tipo: Conferência ou Objeto de Conferência
Publicado em 15/02/2008 Português
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57.31842%
Attempts were made earlier to synthesize and activate the FeTi intermetallic during ball milling (BM), for H2 storage using sodium boron tetra-hydride (NaBH4) additive as a process controlling agent. Simple reactive milling starting from Fe and Ti powders resulted in heavy agglomeration of powders, due to the self sustaining nature of the reaction following an incubation period. When NaBH4 was used as the process control agent to avoid agglomeration, this resulted in the production of titanium hydride besides FeTi, and as a consequence unfavorable irreversibility in the subsequent hydrogen charging/discharging cycles [1,2,12]. The present work reports on modifications introduced in the synthesis process by changing two processing parameters, namely the milling energy and atmosphere composition

‣ Effects of NaBH4 additions on hydrogen absorption by nanostuctured FeTi powders

Marques, Sofia Figueiredo; Correia, J. Brito; Shohoji, Nobumitsu; Rangel, C. M.; Paiva, T. I.
Fonte: Laboratório Nacional de Energia e Geologia Publicador: Laboratório Nacional de Energia e Geologia
Tipo: Conferência ou Objeto de Conferência
Publicado em /04/2007 Português
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Hydrogen is nowadays considered as one of the most promising fuels for the future transportation market, since it is highly energetic and its combustion products are non-toxic. There are however some inherent problems related to its handling and storage that makes its implementation difficult in the energy market [1]. One way of storing hydrogen is in form of intermetallic hydrides. Some intermetallics can store large amounts of hydrogen in their interstitial sites and, in some cases, reversible equilibrium absorption/desorption cycles might be realized near ambient temperature and normal pressure. FeTi is an intermetallic compound that is being widely studied for hydrogen storage purposes. This system has one of the highest volumetric storage capacities and can be produced at low cost [2,3]. However, the FeTi alloy prepared through conventional metallurgical process requires activation treatments at elevated temperature. It has been shown previously that the nanostructured FeTi can be activated at room temperature with the mechanical alloying of pure metallic constituents, Fe and Ti, with NaBH4 [4]. In this work nanostructured FeTi based powders were produced by mechanical alloying, and the effects of adding different amounts of NaBH4 on the hydrogen absorption capacity and on the agglomeration of the powders were studied. The effect of handling powders in a glovebox with oxygen free atmosphere or in atmospheric ambient condition was also examined. Several parameters of the as-milled powders were controlled. Among the characterization performed are phase identification and crystallite size determinations by X-ray diffraction...

‣ The effect of palladium coating on hydrogen storage alloy electrodes for nickel/metal hydride batteries

Visintin,A.; Tori,C.A.; Garaventta,G.; Triaca,W.E.
Fonte: Sociedade Brasileira de Química Publicador: Sociedade Brasileira de Química
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/01/1997 Português
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Charge / discharge studies carried out on Pd - coated misch metal - based alloys for use in nickel-metal hydride batteries are presented. The effect of Pd coating on the voltammetric characteristics, life cycle behavior, and rate capability of the alloy electrodes was determined. The number of cycles required to activate the alloy electrodes decreases with an increase in the Pd content. The results also show that Pd - coated alloys exhibit higher storage capacities and better performance than bare alloys.This improved performance can be attributed to the catalytic effect of Pd on the hydrogen electrode reaction.

‣ Effect of fluorination treatment on electrochemical properties of M1Ni3.5Co0.6Mn0.4Al0.5 hydrogen storage alloy

Huang,Hongxia; Huang,Kelong
Fonte: Sociedade Brasileira de Química Publicador: Sociedade Brasileira de Química
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/05/2012 Português
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The influence of surface treatment by solutions of NH4F, LiF and LiF containing KBH4 on the structure and electrochemical properties of the M1Ni3.5Co0.6Mn0.4Al0.5 hydrogen storage alloy (in which M1 denotes mischmetal) is investigated. The fluorination treatment improves the electrochemical performances of the M1Ni3.5Co0.6Mn0.4Al0.5 alloy. The maximum discharge capacity (Cmax) increases from 314.8 to 325.7 (NH4F), 326.5 (LiF) and 316.4 mAh g-1 (LiF+KBH4). After 60 cycles, the capacity retention rate increases from 83.5 to 84.8% (NH4F), 89.5% (LiF) and 93.9% (LiF+KBH4). The results of the linear polarization and anodic polarization reveal that the exchange current density (I0) and the limiting current density (I L) increase after fluorination treatment, indicating an improvement of the kinetics of the hydrogen absorption/desorption.

‣ Homogeneous Catalytic Dehydrogenation of Formic Acid: Progress Towards a Hydrogen-Based Economy

Laurenczy,Gábor; Dyson,Paul J.
Fonte: Sociedade Brasileira de Química Publicador: Sociedade Brasileira de Química
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/12/2014 Português
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One of the limiting factors to a hydrogen-based economy is associated with the problems storing hydrogen. Many different approaches are under evaluation and the optimum approach will not be the same for all applications, i.e., static, mobile, small and large scale needs, etc. In this article we focus on formic acid as a promising molecule for hydrogen storage that, under certain catalytic conditions, can be dehydrogenated to give highly pure hydrogen and carbon dioxide with only extremely low levels of carbon monoxide gas produced. We describe the various homogeneous catalysts available that usually operate in aqueous formic acid solutions. We also briefly describe the reverse reaction that would contribute to making the use of formic acid in hydrogen storage even more attractive.

‣ Mg2FeH6-based nanocomposites with high capacity of hydrogen storage processed by reactive milling

Asselli,Alexandre Augusto Cesario; Jorge Junior,Alberto Moreira; Ishikawa,Tomaz Toshimi; Botta Filho,Walter José
Fonte: ABM, ABC, ABPol Publicador: ABM, ABC, ABPol
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/04/2012 Português
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The compound Mg2FeH6 was synthesized from a 2Mg-Fe mixture in a single process through high-energy ball milling under hydrogen atmosphere at room temperature. The complex hydride was prepared from Mg powder and granulated or powdered Fe using a planetary mill. The phase evolution during different milling times was performed by X-rays diffraction technique. The dehydrogenation behavior of the hydride was investigated through simultaneous thermal analyses of differential scanning calorimetry and thermogravimetry coupled with mass spectrometer. The use of powdered iron as starting material promoted conversion to complex hydride at shorter milling times than when granulated iron was used, nevertheless, after 24 hours of milling the 2Mg-Fe (powdered or granulated) mixtures presented similar dehydrogenation behavior. The hydrogen absorption during milling was on average 3.2 wt. (%), however, changing the proportions of the reagents to 3Mg-Fe a Mg2FeH6-MgH2 based nanocomposite with higher density of hydrogen (5.2 wt. (%)) was obtained.

‣ Magnesium-Nickel alloy for hydrogen storage produced by melt spinning followed by cold rolling

Leiva,Daniel Rodrigo; Costa,Hevlin Cristina de Almeida; Huot,Jacques; Pinheiro,Tiago Santos; Jorge Junior,Alberto Moreira; Ishikawa,Tomaz Toshimi; Botta Filho,Walter José
Fonte: ABM, ABC, ABPol Publicador: ABM, ABC, ABPol
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/10/2012 Português
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Severe plastic deformation routes (SPD) have been shown to be attractive for short time preparation of magnesium alloys for hydrogen storage, generating refined microstructures and interesting hydrogen storage properties when compared to the same materials processed by high-energy ball milling (HEBM), but with the benefit of higher air resistance. In this study, we present results of a new processing route for Mg alloys for hydrogen storage: rapid solidification followed by cold work. A Mg97Ni3 alloy was processed by melt spinning (MS) and by extensive cold rolling (CR). Submitting Mg97Ni3 ribbons between steel plates to cold rolling has shown to be a viable procedure, producing a thin cold welded foil, with little material waste. The as-processed material presents a high level of [002] fiber texture, a sub microcrystalline grain structure with a high density of defects, and also a fine dispersion of Mg2Ni nanoparticles. This refined microstructure allied to the developed texture resulted in enhanced activation and H-sorption kinetics properties.

‣ Clean Hydrogen Production and Carbon dioxide Capture Methods

Kumar, Sushant
Fonte: FIU Digital Commons Publicador: FIU Digital Commons
Tipo: Artigo de Revista Científica Formato: application/pdf
Português
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Fossil fuels constitute a significant fraction of the world’s energy demand. The burning of fossil fuels emits huge amounts of carbon dioxide into the atmosphere. Therefore, the limited availability of fossil fuel resources and the environmental impact of their use require a change to alternative energy sources or carriers (such as hydrogen) in the foreseeable future. The development of methods to mitigate carbon dioxide emission into the atmosphere is equally important. Hence, extensive research has been carried out on the development of cost-effective technologies for carbon dioxide capture and techniques to establish hydrogen economy. Hydrogen is a clean energy fuel with a very high specific energy content of about 120MJ/kg and an energy density of 10Wh/kg. However, its potential is limited by the lack of environment-friendly production methods and a suitable storage medium. Conventional hydrogen production methods such as Steam-methane-reformation and Coal-gasification were modified by the inclusion of NaOH. The modified methods are thermodynamically more favorable and can be regarded as near-zero emission production routes. Further, suitable catalysts were employed to accelerate the proposed NaOH-assisted reactions and a relation between reaction yield and catalyst size has been established. A 1:1:1 molar mixture of LiAlH4...

‣ Development of a Hydrogen Producing Thermal Control for Chemical Hydrogen Storage

St. John, Adam
Fonte: Quens University Publicador: Quens University
Tipo: Tese de Doutorado Formato: 4339132 bytes; application/pdf
Português
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This thesis investigated a potential improvement to hydrogen storage for fuel cells using a thermally efficient hydrogen storage method. The efficiency of the storage system was improved using a metal hydride system to act as a thermal control unit for an exothermic chemical hydrogen storage system. A cylindrical shaped “hybrid” reactor was created to allow hydrogen production from a sodium borohydride packed bed reactor and the metal hydride. Additionally, a custom built pressure-composition-temperature apparatus was built to record the amount of hydrogen desorption from the metal hydride while isolating the metal from potential poisons such as oxygen. Before using the chemical hydride packed bed, heat transfer through the reactor was studied using circulating water. The water experiments showed that an increase in heat flux to the reactor led to a faster desorption rate of hydrogen from the metal hydride resulting in a larger temperature drop throughout the reactor. After the operating characteristics of the hybrid reactor were studied, a 10 wt% solution of sodium borohydride was created and pumped through the packed bed to produce enough hydrogen for a 300 W fuel cell. The amount of heat produced from the packed bed portion of the reactor was significant...

‣ Nanoestruturas de carbono para o armazenamento de hidrogênio : estudos computacionais; Carbon nanostructures for hydrogen storage : computational studies

Tatiana Mello da Costa Faro
Fonte: Biblioteca Digital da Unicamp Publicador: Biblioteca Digital da Unicamp
Tipo: Tese de Doutorado Formato: application/pdf
Publicado em 28/01/2015 Português
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Atualmente, a economia mundial depende do uso de combustíveis fósseis para a geração de energia. Esse modelo apresenta problemas ambientais graves, uma vez que o petróleo é um material não-renovável e muito poluente. O gás hidrogênio apresenta-se como uma alternativa promissora para substituir os combustíveis utilizados atualmente devido a um conjunto de características positivas: ele é atóxico, tem uma alta densidade energética gravimétrica e gera apenas água como produto de sua combustão. Apesar de tais vantagens, ele ainda não é utilizado comercialmente em larga escala. O maior empecilho tecnológico para que o hidrogênio possa substituir os combustíveis fósseis está no seu armazenamento. Existem diversas propostas para armazenar o hidrogênio, como tanques contendo o hidrogênio nas formas de gás pressurizado ou de líquido, além de sistemas sólidos que permitam a sua adsorção. Todavia, nenhum sistema construído até então foi capaz de armazenar o hidrogênio de forma tão barata, segura e eficaz quanto seria necessário. Nanoestruturas de carbono são vistas como uma boa alternativa para construir dispositivos de armazenamento de hidrogênio baseados na fisissorção. Os nanopapiros de carbono, formados por folhas de grafeno enroladas no formato de um papiro...

‣ Improving hydrogen storage in Ni-doped carbon nanospheres

Zubizarreta, Leire; Menéndez Díaz, José Ángel; Pis Martínez, José Juan; Arenillas de la Puente, Ana
Fonte: Elsevier Publicador: Elsevier
Tipo: Artículo Formato: 9211995 bytes; application/pdf
Português
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7 pages, 8 figures.-- Article in press.; The effect of nickel distribution and content in Ni-doped carbon nanospheres on hydrogen storage capacity under conditions of moderate temperature and pressure was studied. It was found that the nickel distribution, obtained by using different doping techniques and conditions, has a noticeable influence on hydrogen storage capacity. The samples with the most homogeneous nickel distribution, obtained by pre-oxidising the carbon nanospheres, displayed the highest storage capacity. In addition, storage capacity is influenced by the amount of nickel. It was found a higher storage capacity in samples containing 5 wt.% of Ni. This is due to the greater interactions between the nickel and the support that produce a higher activation of the solid through a spillover effect.; L.Z. acknowledges the support received from the CSIC I3P Programme co-financed by the European Social Fund. The authors would like to thank BIOGAS FUEL CELL (Project CENIT BAIP 2020) for their financial support.; Peer reviewed

‣ Activation of carbon nanofibres for hydrogen storage

Blackman, James M.; Patrick, John W.; Arenillas de la Puente, Ana; Shi, Wei; Snape, Colin E.
Fonte: Elsevier Publicador: Elsevier
Tipo: Artículo Formato: 918459 bytes; application/pdf
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10 pages, 10 figures, 6 tables.-- Printed version published Jul 2006.; The present study was aimed to investigate different methods of activation of carbon nanofibres, CNF, in order to determine the beneficial effect on the hydrogen sorption capacities of increasing the surface area. Two activation systems were used: physical activation with CO2 and chemical activation with KOH. A range of potential adsorbents were thus prepared by varying the temperature and time of activation. The structure of the CNF proved more suitable to activation by KOH than by CO2, with the former yielding higher surface area carbons (up to 1000 m2 g−1). The increased surface area, however, did not correspond directly with a proportional increase in hydrogen adsorption capacity. Although high surface areas are important for hydrogen storage by adsorption on solids, it would appear that it is essential that not only the physical, but also the chemical, properties of the adsorbents have to be considered in the quest for carbon based materials, with high hydrogen storage capacities.; The financial support of the EPSRC (Engineering and Physical Sciences Research Council) and Air Products and Chemicals, Inc. is gratefully acknowledged.; Peer reviewed

‣ Influence of particle size on electrochemical and gas-phase hydrogen storage in nanocrystalline Mg

Friedrichs, O.; Kolodziejczyk, L.; Sánchez López, Juan Carlos; Fernández-Camacho, A.; Lyubenova, L.; Zander, Daniela; Kösterc, U.; Aguey-Zinsou, K.F.; Klassend, T.; Bormann, R.
Fonte: Elsevier Publicador: Elsevier
Tipo: Artículo Formato: 22195 bytes; application/pdf
Português
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7 pp. Published in Journal of Alloys and Compounds Copyright © 2007 Elsevier B.V.; Nanocrystalline Mg powders of different particle size were obtained by inert gas evaporation and studied during electrochemical and gas-phase hydrogen cycling processes. The samples were compared to dehydrided samples obtained by mechanical milling of MgH2 with and without 2 mol% Nb2O5 as catalyst. The hydrogen overpotential of the pure Mg, which is a measure of the hydrogen evolution at the electrode surface, was observed to be reduced with smaller particle sizes reaching values comparable to samples with Nb2O5 additive. On the other hand gas-phase charging experiments showed the capacity loss with smaller particle sizes due to oxidation effects. These oxidation effects are different depending on the synthesis method used and showed a major influence on the hydrogen sorption kinetics.; Authors thank the financial support (project nos. HPRN-CT-2002-00208 and MRTN-CT-2006-035366) from the European Commission; Peer reviewed

‣ Structure and Morphology Control in Carbon Nanomaterials for Nanoelectronics and Hydrogen Storage

McNicholas, Thomas Patrick
Fonte: Universidade Duke Publicador: Universidade Duke
Tipo: Dissertação Formato: 72691400 bytes; application/pdf
Publicado em //2009 Português
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Carbon nanomaterials have a wide range of promising and exciting applications. One of the most heavily investigated carbon nanomaterial in recent history has been the carbon nanotube. The intense interest in carbon nanotubes can be attributed to the many exceptional characteristics which give them great potential to revolutionize modern mechanical, optical and electronic technologies. However, controlling these characteristics in a scalable fashion has been extremely difficult. Although some progress has been made in controlling the quality, diameter distribution and other characteristics of carbon nanotube samples, several issues still remain. The two major challenges which have stood in the way of their mainstream application are controlling their orientation and their electronic characteristics. Developing and understanding a Chemical Vapor Deposition based carbon nanotube synthesis method has been the major focus of the research presented here. Although several methods were investigated, including the so-called "fast-heating, slow-cooling" and large feeding gas flowrate methods, it was ultimately found that high-quality, perfectly aligned carbon nanotubes from a variety of metal catalysts could be grown on quartz substrates. Furthermore...

‣ Hydrogen storage systems based on metal hydrides with efficient heat removal

Wang, Hui
Fonte: University of Delaware Publicador: University of Delaware
Tipo: Tese de Doutorado
Português
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Prasad, Ajay K.; Advani, Suresh G.; The overall objective of this research was to accelerate the rate at which hydrogen gas can be charged into a hydride-based hydrogen storage tank. During the charging process, the absorption reaction of hydrogen gas into a metal hydride bed is exothermic. The temperature of the system will increase if the heat released is not removed quickly from the system and reduce the absorption rate. Hence, the rate of hydrogen storage into a tank containing metal hydride materials strongly depends on the heat removal rate from the hydrogen storage system. To increase the heat removal rate the following four approaches were explored: (i) Enhancement of the thermal conductivity of the metal hydride bed by incorporating conductivity-enhancing materials such as aluminum (Al) foam. (ii) The use of genetic algorithms to optimize the parameters and placement of spiral coil heat exchangers with fins. (iii) Introduction of an active cooling environment by embedding a helical coil heat exchanger into the hydrogen storage tank. (iv) Use of a physical mixing method to improve the heat removal rate. In order to investigate the effectiveness and the role of various factors in the above proposed approaches, we developed a numerical model that incorporates flow...

‣ Role of Lithium Decoration on Hydrogen Storage Potential

Pan,Sudip; Banerjee,Swastika; Chattaraj,Pratim K.
Fonte: Sociedad Química de México A.C. Publicador: Sociedad Química de México A.C.
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/09/2012 Português
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Hydrogen storage potential of two sets of lithium containing systems, viz., Li-doped borazine derivatives and various bond-stretch isomers of Li3Al4- is studied at the B3LYP/6-311+G(d) level of theory occasionally supplemented by the results from the associated MP2/6-31+G(d) calculations. Negative values of interaction energy, reaction enthalpy, reaction electrophilicity, and desorption energies for the gradual hydrogen-trapping processes justify the efficacy of these systems as the hydrogen storage material. Presence of Li as well as aromaticity improves the situation. Various conceptual density functional theory based reactivity descriptors like electronegativity, hardness, and electrophilicity and the associated electronic structure principles such as the principles of maximum hardness and minimum electrophilicity lend additional support.

‣ The Storage of Hydrogen in Nanoporous Carbons

Alonso,Julio A.; Cabria,Iván; López,María J.
Fonte: Sociedad Química de México A.C. Publicador: Sociedad Química de México A.C.
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/09/2012 Português
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An efficient storage of hydrogen is a crucial requirement for its use as a fuel in the cars of the future. Experimental and theoretical work has revealed that porous carbons are promising materials for storing molecular hydrogen, adsorbed on the surfaces of the pores. The microstructure of porous carbons is not well known, and we have investigated a class of porous carbons, the carbide-derived carbons, by computer simulation, showing that these materials exhibit a structure of connected pores of nanometric size, with graphitic-like walls. We then apply a thermodynamical model of hydrogen storage in planar and curved pores. The model accounts for the quantum effects of the motion of the molecules in the confining potential of the pores. The optimal pore sizes yielding the highest storage capacities depend mainly on the shape of the pore, and slightly on temperature and pressure. At 300 K and 10 MPa, the optimal widths of the pores lie in the range 6-10 Å. The theoretical predictions are consistent with experiments for activated carbons. The calculated storage capacities of those materials at room temperature fall below the targets. This is a consequence of an insufficiently strong attractive interaction between the hydrogen molecules and the walls of carbon pores. Recent work indicates the beneficial effect of metallic doping of the porous carbons in enhancing the binding energy of H2 to the pore walls...