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Abstract: In this work, the tests of a hydrogen storage system intended for vehicular applications, using a metal hydride as storage material, are reported. The system is designed to deliver gas to a fuel cell prototype vehicle. The room temperature hydride is an interstitial alloy, which is selected for its capacity to absorb and desorb hydrogen over an appropriate range of temperature and pressure. The static tests aim to assess whether the requirements for hydrogen release are reliably met by the tank setup. Hypothetical on‐road tests have been designed and applied. Dynamic tests allow moving from energy to power density. Solutions are adopted to face the issues of thermal management at higher‐demanding performances. Several cycles have been performed to find the ideal settings to preserve high average and peak gas flow in a realistic situation. The use of a metal hydride, to replace pressurized gas, results in improved performances, including an extended range at lower loading pressures. Decreasing the pressure in the storage system enables the advantageous possibility to reload the tank several times with commercially available cylinders. Possible future enhancements in the reduction of the total weight of the system are also considered. [ABSTRACT FROM AUTHOR]

Abstract: Several mixtures of LiBH4 and Mg(BH4)2 borohydrides in different stoichiometric ratios (1:0, 2:1, 1:1, 1:2, 0:1), prepared by high energy ball milling, have been investigated with X-ray powder diffraction and thermal programmed desorption (TPD) volumetric analysis to test the dehydrogenation kinetics in correlation with the physical mixture composition. Afterwards mixed and unmixed borohydrides were dispersed on high specific surface area ball milled graphite by means of the solvent infiltration technique. BET and statistical thickness methods were used to characterize the support surface properties, and SEM micrographs gave a better understanding of the preparation techniques. It has been observed by TPD volumetric measurements that the confinement of the reactive borohydrides on the nanoporous supports leads to a lower dehydrogenation temperature compared to unsupported borohydrides. Moreover, a further decrease of the dehydrogenation temperature has been observed by increasing the specific surface area of the support and the pores volume and by using the prepared mixtures instead of pure materials. The dehydrogenation process seems to be favoured by the heterogeneous nucleation on the graphite surface of decomposition products or intermediate phases from melted liquid borohydrides. [Copyright &y& Elsevier]

Hydrogen is an efficient energy carrier that can be produced from renewable sources, enabling the transition towards CO 2 -free energy. Hydrogen can be stored for a long period in the solid-state, with suitable alloys. Ti-rich TiFe 0.90 compound exhibits a mild activation process for the first hydrogenation, and Ti(Fe,Mn) 0.90 substituted alloys can lead to the fine tuning of equilibrium pressure as a function of the final application. In this study, the crystal structure of TiFe (0.90- x) Mn x alloys (x = 0, 0.05 and 0.10) and their deuterides has been determined by in-situ neutron diffraction, while recording Pressure-Composition Isotherms at room temperature. The investigation aims at analysing the influence of Mn for Fe substitution in Ti-rich Ti(Fe,Mn) 0.90 alloys on structural properties during reversible deuterium loading, which is still unsolved and seldom explored. After activation, samples have been transferred into custom-made stainless-steel and aluminium alloy cells used for in-situ neutron diffraction experiments during deuterium loading at ILL and ISIS neutron facilities, respectively. The study enables remarkable understanding on hydrogen storage, basic structural knowledge, and support to the industrial application of TiFe-type alloys for integrated hydrogen tank in energy storage systems by determining the volume expansion during deuteration. Furthermore, the study demonstrates that different contents of Mn do not significantly change the volumetric expansion during phase transitions, affecting only the deuterium content for the γ phase and the cell evolution for the β phase. The study confirms that the deuterated structures of the γ phase upon absorption, β and α phase upon desorption, correspond to S.G. Cmmm , P 222 1 and Pm -3 m , respectively. [Display omitted] • Effect of Mn content on structural and hydrogenation properties in TiFe determined. • Mn-substituted TiFe deuterates structures determined by in situ neutron diffraction. • Mn does not significantly change volumetric expansion during phase transitions. • Mn substitution affects deuterium content for γ and cell evolution for β phase. • Mn substitution favours a stable deuterium occupancy over 2 a and 2 d sites. [ABSTRACT FROM AUTHOR]

Abstract: On the basis of a previously acquired experience on scaling up issues concerning the use of magnesium hydride as a base material for solid-state hydrogen storage, a small reactor was designed and tested in different operating conditions. It contains about 10g of catalyzed magnesium hydride powder mixed with 5wt.% aluminium powder and pressed in the form of cylindrical pellets and the heat flow is managed by means of an oil circulation system. Carbon paper is used to ensure good heat conductivity between the pellets and the inner wall of the reactor and between one pellet and another. A number of hydrogen absorption and desorption cycles at different temperatures and pressures was carried out to compare the behaviour of the small reactor with the laboratory data obtained on small amounts (fractions of grams) of powdered and pelletized samples. Data acquisition for gas flow, pressure and temperature in different positions of the reactor allow a good understanding of internal dynamics. The results in terms of hydrogen absorption/desorption kinetics and of stability to ongoing cycles are stimulating, so that the tested small reactor can be considered as a basic element for further studies and improvements. [Copyright &y& Elsevier]