Hydrure

Résumé

L'ion hydrure est l'anion d'hydrogène H. Par extension, le terme hydrure désigne un composé chimique constitué d'hydrogène et d'un autre élément encore moins électronégatif (ou d'électronégativité comparable). À l’origine le terme « hydrure » était strictement réservé à des composés contenant des métaux, mais la définition a été étendue à des composés où l’hydrogène a un lien direct avec un autre élément, et où l'hydrogène est l'élément le plus électronégatif. Types Les hydrures peuvent être classés selon les types de liaisons et la nature des substances liées : *Hydrures métalloïdiques à liaison covalente ; *Hydrures métalliques : **Hydrures ioniques ; **hydrures à liaison covalente ; **Composés d’insertion de l’hydrogène dans un réseau métallique. Dans les hydrures contenant des éléments des groupes principaux, l’électronégativité d’un élément par rapport à celle de l’hydrogène détermine si le composé est de l’un des deux premiers types. Les métaux électropositifs, à la

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https://fr.wikipedia.org/wiki/Hydrure

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In this work, we have studied various aspects of catalysts and catalytic processes at the solid-liquid interface, e.g. the reduction of supported PdO, the formation of Pd hydrides, their quantification, the their reactivity in a transient in time-resolved manner, Ru and P-modified Ru based catalysts and zeolites. In order to provide structural information mainly X-ray absorption spectroscopy, infrared spectroscopy and X-ray diffraction were used, while the measurements were made possible by the realization of a dedicated setup including reactor cells. The cells are designed to allow for monitoring structural changes of oxidation state and nature of adsorbates in a time-resolved manner. This is of particular interest to study the reactivity of species, such as the Pd hydrides, formed on the catalyst in the liquid environment exploiting tools that are already widely applied to study gas phase reactions.

EPFL2020

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CO2 hydrogenation on a metal hydride surface

Davide Ferri, Shunsuke Kato

The catalytic hydrogenation of CO 2 at the surface of a metal hydride and the corresponding surface segregation were investigated. The surface processes on Mg 2NiH 4 were analyzed by in situ X-ray photoelectron spectroscopy (XPS) combined with thermal desorption spectroscopy (TDS) and mass spectrometry (MS), and time-of-flight secondary ion mass spectrometry (ToF-SIMS). CO 2 hydrogenation on the hydride surface during hydrogen desorption was analyzed by catalytic activity measurement with a flow reactor, a gas chromatograph (GC) and MS. We conclude that for the CO 2 methanation reaction, the dissociation of H 2 molecules at the surface is not the rate controlling step but the dissociative adsorption of CO 2 molecules on the hydride surface. © the Owner Societies 2012.

2012

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An energy economy based on renewable energy requires massive energy storage, approx. half of the annual energy consumption. Therefore, the production of a synthetic energy carrier, e.g. hydrogen, is necessary. The hydrogen cycle, i.e. production of hydrogen from water by renewable energy, storage and use of hydrogen in fuel cells, combustion engines or turbines is a closed cycle. Electrolysis splits water into hydrogen and oxygen and represents a mature technology in the power range up to 100 kW. However, the major technological challenge is to build electrolyzers in the power range of several MW producing high purity hydrogen with a high efficiency. After the production of hydrogen, large scale and safe hydrogen storage is required. Hydrogen is stored either as a molecule or as an atom in the case of hydrides. The maximum volumetric hydrogen density of a molecular hydrogen storage is limited to the density of liquid hydrogen. In a complex hydride the hydrogen density is limited to 20 mass% and 150 kg/m(3) which corresponds to twice the density of liquid hydrogen. Current research focuses on the investigation of new storage materials based on combinations of complex hydrides with amides and the understanding of the hydrogen sorption mechanism in order to better control the reaction for the hydrogen storage applications.

Swiss Chemical Soc2015

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