Papers by Keyword: Metal Hydride

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Authors: Xu Yang Chen, Ling Xiao Wei, Lan Deng, Fu Sheng Yang, Zao Xiao Zhang
Abstract: With the expansion of application fields of the high purity hydrogen (hydrogen content>99.9999%), its preparation methods, in particular recovery from multi-component mixture,have attracted wide attentions. This paper describes the principle of hydrogen separation and purification process based on metal hydride, and some key issues involved in it, such as the alternatives of raw gas, the processing of hydride materials, the design of metal hydride reactor are discussed according to the literature reports. Finally, the current problems encountered in hydride based gas separation are presented, and future trends are also predicted.
Authors: Hadi Suwarno
Abstract: The synthesis and characterizations of Fe-Ti and Mg-Ti-Fe alloys with the atomic ratio of Fe:Ti = 2:1 and Mg:Ti:Fe = 2:5:6 prepared by mechanical alloying technique in toluene solution and measurement the hydrogen absorption properties of the yields have been performed. The Fe-Ti and Mg-Ti-Fe elemental powders are milled with the milling time of 30 h, in a Mixer Mill, type PW 700i high energy ball mill. The milled specimens are analyzed with an X-ray diffractometer, Philip, type PW 1710, using Cu as the anode tube and l = 1.5406 Å. Qualitative and quantitative analyses are determined using Rietveld method developed by Fuji Izumi. The microstructure of the specimens after milling and hydriding are identified with a scanning electron microscope, Philip type 550. The refinement analysis of the x-ray diffractions results for Fe-Ti alloy shows that before milling the specimen consists of Ti and Fe phases, and after 30 h of milling new phases identified as FeTi and Fe2Ti are formed. In case of Mg-Ti-Fe alloy after 30 h of milling new phases identified as Fe2Ti and FeTi compounds are formed with the absence of Mg-Ti and Mg-Fe. Quantitative analysis of the milled powders shows that the mass fractions of FeTi and Fe2Ti phases are correspondingly 22.5 wt% and is 21.1 wt%, and the rest is Fe. The disappearance of Mg peaks after milling is suggested from the transformation of the crystallite into amorphous state. On hydriding at room temperature, the milled Fe-Ti and Mg-Fe-Ti powders are transformed into b-Ti4FeH8.5, Fe and TiH2. Considering the high hydrogen capacity and the low hydriding temperature of the Mg-Ti-Fe alloy compared to those of Fe-Ti alloy, the Mg-Ti-Fe alloy could be promoted as a new hydrogen storage material.
Authors: Wu Tsan Wu, Jing Shan Do
Abstract: The charge/discharge properties of commercial metal hydride alloy powder (MmNi3.81Mn0.41Al0.19Co0.76) is improved and modified by electroless plating nickel. The effect of concentration of reducing agent (Cr), concentration of complex agent (Cc), reaction temperature (T), reaction time (t), and the amounts of MH powder per volume (CMH) on the utilization of the modified MH alloy used as the negative electrode of Ni/MH battery is systematically studied. The utilization of modified MH alloy is mainly affected by Cr, Cc and t. The utilizations of MH alloys modified with condtions of T = 70 oC, t = 90 min, Cr = 20 g l-1, Cc = 20 g l-1 and CMH = 20 g l-1, respectively, are obtained to be 92.3, 64.7 and 23.6% at discharging rate of 1, 4, and 10 C. The utilizations of modified MH alloy are increased by 15.5, 45.6 and 19.8% compared with the pristine MH alloy for discharging rates of 1, 4 and 10 C, respectively.
Authors: Bao Zhong Liu, Yan Ping Fan, Bao Qing Zhang
Abstract: Ti45Zr30Ni25RE3 (Y, La) alloys were prepared by melt-spun at wheel velocities of 20 m s–1. Ti45Zr30Ni25 and Ti45Zr30Ni25La3 were composed of I-phase, amorphous and Laves phases. Ti45Zr30Ni25Y3 consisted of amorphous phase and I-phase. The addition of La and Y caused the decrease of maximum discharge capacity and the increase of cycling stability, which should be ascribed to the change of various phase abundant. The high-rate dischargeability of Ti45Zr30Ni25 alloy electrode was better than that of Ti45Zr30Ni25Y3 and Ti45Zr30Ni25La3 alloy electrode, which was attributed to the better electrochemical kinetics.
Authors: Stepan Alexandrovich Lushnikov
Abstract: After hydrogen desorption from hydrides based on crystal and partly amorphous CeNi3 compounds samples were obtained with a composition CeNi3Нx (x = 0.5, 0.9). All samples were investigated by X-ray diffraction under the usual conditions. It was revealed that samples after hydrogen desorption have hexagonal and orthorhombic structure of the metallic matrix with cell parameters close to the initial alloy CeNi3. Such structural behavior under hydrogen desorption is determined by the desorption conditions and depends on different hydrogen diffusion in the lattice.
Authors: Yan Wang, Shi Wei Wu, Tian Le Li, Shen Shen Li, Zhong Qiu Cao
Abstract: Recently, Magnesium hydride MgH2 is one of the attractive hydrogen storage materials because it reaches a high hydrogen capacity. However, the reaction kinetics is too slow and needs high temperature for progressing hydrogen absorption and desorption reactions, which hinders the process of practical applications and it is necessary to improve the hydrogen storage propesties. In this paper, most used or under research methods (Doping with metal and compound) of improving on the hydrogen storage of magnesium hydride are reviewed, in particular to elements substitution, addition of transition metal oxides or fluorine and so on. The advantages and disadvantages of vaious methods of improving on the hydrogen storage of magnesium hydride are compared. The trend of the methods of improving is also introduced.
Authors: Sofoklis S. Makridis, A. Ioannidou, Erik Zupanič, Albert Prodan, E.S. Kikkinides, Athanasios K. Stubos
Abstract: Hydrogen storage in reversible metal hydrides is attractive because it can be stored at relatively low pressures with a high volumetric density. In the present research work have been investigated compounds with nominal compositions Zr0.8Ti0.2Cr1.2V0.4Ni0.4 and Zr0.8Ti0.2Cr0.8V0.8Ni0.4 that have been prepared by arc-melting under argon atmosphere. Structural characteristics have been studied by using X-ray powder diffraction while the patterns have been analyzed by using the Rietveld analysis. A main hexagonal Laves phase MgZn2 (C14) and a secondary MgCu2 (C15)-type of, have been found in the powdered compounds. The bulk samples have composite microstructures but the V-rich is characterized by a dendritic microstructure. The high resolution scanning electron microscopy (HR-SEM) and energy dispersive X-ray analysis (EDAX) have been used for the morphology and quantitative analysis, respectively. Hydrogenations and dehydrogenations have been obtained after crucial activation procedure. The alloys were found to be more active under hydrogen after activation while the desorbed amount of hydrogen has been measured by using a Sievert-type apparatus.
Authors: Yong Soon Yap, Chi Hung Peng, Chi Chang Wang
Abstract: This study analyzed and discussed the hydrogen storage reaction in the metal hydride hydrogen storage tank with internally fined heat tube. As the heat transfer and hydrogen storage efficiency of internal temperature control system are better than external temperature control, this study created a hydrogen storage simulation method to discuss the effect of thermistor fins on hydrogen storage. The results showed that the fins have significant effect on increasing the hydrogen storage efficiency, and the hydrogen storage time decreases as the thermistor fluid velocity increases, but the drawback is not apparent when the fluid velocity reaches a threshold.
Authors: Giovanni Capurso, Julian Jepsen, José M. Bellosta von Colbe, Claudio Pistidda, Oliver Metz, Deniz Yigit, Hu Jun Cao, Rifan Hardian, Anselm Strauch, Klaus Taube, Thomas Klassen, Martin Dornheim
Abstract: A holistic approach is required for the development of materials and systems for hydrogen storage, embracing all the different steps involved in a successful advance of the technology. The several engineering solutions presented in this work try to address the technical challenges in synthesis and application of solid-state hydrogen storage materials, mainly metal hydride based compounds. Moving from the synthesis of samples in lab-scale to the production of industrial sized batches a novel process development is required, including safety approaches (for hazardous powders), and methods to prevent the contamination of sensitive chemicals. The reduction of overall costs has to be addressed as well, considering new sources for raw materials and more cost-efficient catalysts. The properties of the material itself influence the performances of the hydride in a pilot storage tank, but the characteristics of the system itself are crucial to investigate the reaction limiting steps and overcome hindrances. For this, critical experiments using test tanks are needed, learning how to avoid issues as material segregation or temperature gradients, and optimizing the design in the aspects of geometry, hull material, and test station facilities. The following step is a useful integration of the hydrogen storage system into real applications, with other components like fuel cells or hydrogen generators: these challenging scenarios provide insights to design new experiments and allow stimulating demonstrations.
Authors: Donald L. Anton, Charles W. James, David A. Tamburello, Jose A. Cortes-Concepcion, Joshua R. Gray, Kyle S. Brinkman
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