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AbstractAbstract
[en] In the last decade, boron- and nitrogen- based compounds have been considered as potential materials for chemical hydrogen storage due to their unique properties. Ammonia borane (NH3BH3, AB, 19.5 wt. % H) and hydrazine borane (N2H4BH3, HB, 15.4 wt. % H) are two of the most representative examples. However, these materials cannot be used in the pristine state due to different drawbacks (i.e. release of unwanted byproducts during thermolysis, high dehydrogenation temperature...). To overcome these problems, different approaches have been studied. The chemical modification of AB and HB is one of these options, where a protic hydrogen atom of the molecule is substituted by a metal cation. Thereby, the derivatives of AB and HB (amido-boranes and hydrazinidoboranes) have emerged with improved dehydrogenation properties. In this work, the last two members of the alkali derivatives of hydrazine borane are presented. Rubidium hydrazinidoborane (RbN2H3BH3, RbHB, 4.6 wt. % H) and cesium hydrazinidoborane (CsN2H3BH3, CsHB, 3.4 wt. % H) were obtained by a wet synthesis between hydrazine borane and the respective alkali metal. Two new crystalline solids were obtained. The full characterization of RbHB and CsHB was performed in the context of hydrogen storage materials. The successful introduction of the alkali metal cation and the destabilization of the molecule were confirmed. With the family of alkali derivatives of HB complete, we have a better overview of these materials and the findings are discussed. This thesis also pretends to open new perspectives for amido-boranes. Computational works have shown that boron nitride (BN) can uptake hydrogen or carbon dioxide (CO2) at room conditions. In this way, we selected the lithium and sodium amido-boranes to be studied as precursors of boron nitride-like structures in order to test their gas sorption properties. The formation of hexagonal BN has been observed when the materials were treated at 800 C. The capacity of CO2 capture of these materials was investigated. The results are presented for the first time in this work. (author)
[fr]
Au cours de la derniere decennie, les composes a base de bore et d'azote ont ete consideres comme des materiaux potentiels pour le stockage chimique de l'hydrogene grace a ses proprietes uniques. L'ammoniaborane (NH3BH3, AB, 19.5 wt. % H) et l'hydrazine borane (N2H4BH3, HB, 15.4 wt. % H) sont deux des exemples les plus representatifs. Malheureusement, ces materiaux ne peuvent pas etre utilises a l'etat vierge en raison de differents inconvenients associes a leur deshydrogenation. Pour surmonter ces problemes, plusieurs strategies ont ete considerees. L'une d'elles est la modification chimique de l'AB et de l'HB, ou un des atomes d'hydrogene protique de la molecule est substitue par un cation metallique. Ainsi, les derives de l'AB et de l'HB (amidoboranes et hydrazinidoboranes) ont emerge avec des proprietes de deshydrogenation ameliorees. Dans ce travail, les deux derniers membres des derives alcalins de l'hydrazine borane sont presentes. L'hydrazinidoborane de rubidium (RbN2H3BH3, RbHB, 4.6 m % H) et l'hydrazinidoborane de cesium (CsN2H3BH3, CsHB, 3.4 m % H) ont ete obtenus par une synthese par voie humide entre l'HB et le metal alcalin respectif. Deux nouveaux solides cristallins ont ete obtenus. La caracterisation complete du RbHB et du CsHB a ete realisee dans le contexte des materiaux par le stockage de l'hydrogene. L'introduction reussie du cation alcalin et la destabilisation de la molecule ont ete confirmees par rapport au precurseur HB. La famille des derives alcalins de HB etant complete, nous avons une meilleure vue d'ensemble de ces materiaux et de nouvelles perspectives sont abordees.Cette these a egalement pour objectif d'ouvrir des nouvelles perspectives pour les amidoboranes. Des etudes theoriques ont montre que le nitrure de bore (BN) peut absorber l'hydrogene ou le dioxyde de carbone (CO2) a l'ambiante. Des lors, les amidoboranes de lithium et de sodium ont ete etudies en tant que precurseurs de structures similaires au BN afin d'evaluer leurs proprietes de sorption de gaz. La formation de BN hexagonal a ete observee lorsque les materiaux etaient traites a 800 C. La capacite de captage de CO2 de ces materiaux a ete estimee. Des resultats interessants ont ete obtenus et ils sont presentes dans ce manuscritOriginal Title
Composes de borane pour le stockage chimique de l'hydrogene et la capture de dioxyde de carbone
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19 Feb 2021; 262 p; 570 refs.; Available from the INIS Liaison Officer for France, see the INIS website for current contact and E-mail addresses; Sciences Chimiques
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