Study of an in-situ hydrogen production process by hydrolysis under high pressure with magnesium
Description
Over the past few years, many efforts have been dedicated to hydrogen production from hydrolysis reaction with various materials. This method is promising as it needs no additional energy source and allow for hydrogen to be produced in remote places (off-grid). Among candidate materials, magnesium (Mg) appears particularly interesting as it is very abundant, inexpensive, its reactivity to water oxidation (i.e. hydrolysis) is high and its environmental impact is negligible. This thesis addresses three aspects of this process. The first one concerns the study of hydrolysis reaction in seawater (35 g/mol NaCl) with a family of Mg-rich materials named 'Long Period Stacking Ordered' (LPSO). These ternary phases (Mg-Transition Metal (TM) - Rare Earth (RE)) have structural properties involving an alternation of Mg layers (few atomic planes) and TM-RE enriched layers. This study comprises measurements of hydrogen generation with powders of different alloys as well as corrosion studies on bulk materials. The corrosion and galvanic interactions between α-Mg and LPSO phases are further studied through various techniques (Scanning electron microscopy (SEM), Volta potential measurement...). The second part of the work consists in modeling the hydrolysis kinetics obtained with the different Mg-LPSO alloys. The challenges related to the formulation of a simple and pertinent model that is adapted to hydrolysis reaction are exposed. An approach based on the consumption of the phases (LPSO and α-Mg) is used and a model taking into account these two contributions is proposed. SEM observations of the alloys allow to show the strength and the relevance of this model. Hydrogen generation under high pressure is a very interesting aspect of the process that is also explored in this thesis. This novel study showed the technical challenges related to the important amount of heat released by the reaction of several grams of reactants. Several strategies are presented in order to address these issues. (author)
Abstract (French)
Au cours des dernieres annees, de nombreux efforts ont ete consacres a la production d'hydrogene a partir de reactions d'hydrolyse de divers materiaux. Cette methode est prometteuse car elle ne necessite l'apport d'aucune energie supplementaire et offre la possibilite de produire de l'hydrogene de maniere delocalisee. Parmi les materiaux envisages, le magnesium (Mg) s'avere particulierement interessant puisqu'il est tres abondant, peu onereux, sa reactivite a l'oxydation par l'eau (i.e. hydrolyse) est grande et son impact environnemental est faible. Cette these aborde trois aspects de ce procede. Le premier aspect concerne l'etude de la reaction d'hydrolyse dans l'eau de mer (35 g/mol NaCl) avec une famille de materiaux riches en Mg nommes 'Long Period Stacking Ordered' (LPSO). Ces phases ternaires (Mg-Metal de Transition (MT)-Terre Rare (TR)) presentent des proprietes structurales alternant des plans atomiques de magnesium avec des plans enrichis en MT et TR. Cette etude comporte des mesures de degagement de dihydrogene avec des poudres de differents alliages ainsi que des mesures de corrosion sur des echantillons bruts. Les mecanismes d'interaction galvanique entre les phases α-Mg et LPSO sont etudiees plus en detail par diverses techniques (microscopie electronique a balayage (MEB), mesure du potentiel volta,...) Le second axe d'etude porte sur la modelisation des cinetiques de reaction d'hydrolyse obtenues avec les differents alliages contenant des phases LPSO. Les difficultes liees a la formulation d'un modele simple et adapte au probleme de l'hydrolyse sont exposees. Une approche basee sur la consommation des phases en presence (LPSO et α-Mg) est utilisee et un modele prenant en compte cette double consommation est propose. Les observations MEB des alliages permettent de demontrer et d'affirmer la robustesse et la pertinence de ce modele. Enfin, la possibilite de generer le dihydrogene a haute pression est un atout du procede qui est egalement explore dans cette these. La mise en reaction de plusieurs grammes de reactifs a engendre des problematiques techniques liees notamment a l'exothermicite de la reaction. Plusieurs strategies visant a resoudre ces problematiques sont exposees. (auteur)
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Additional details
Additional titles
- Original title (French)
- Etude d'un procede de production d'hydrogene in-situ sous haute pression par hydrolyse en presence de magnesium
Publishing Information
- Imprint Pagination
- 192 p.
- Report number
- FRNC-TH--14626
INIS
- Country of Publication
- France
- Country of Input or Organization
- France
- INIS RN
- 54076895
- Subject category
- S37: INORGANIC, ORGANIC, PHYSICAL AND ANALYTICAL CHEMISTRY; S36: MATERIALS SCIENCE;
- Resource subtype / Literary indicator
- Thesis
- Descriptors DEI
- ACTIVATION ENERGY; CHEMICAL REACTION KINETICS; CORROSION; HYDROGEN PRODUCTION; HYDROGENATION; HYDROLYSIS; MAGNESIUM; MAGNESIUM HYDRIDES; MICROSTRUCTURE; POTASSIUM CHLORIDES; POTENTIOMETRY; POWDERS; PRESSURE DEPENDENCE; RARE EARTH ADDITIONS; SEAWATER; SODIUM CHLORIDES; TRANSITION ELEMENTS; VOLTAMETRY
- Descriptors DEC
- ALKALI METAL COMPOUNDS; ALKALINE EARTH METAL COMPOUNDS; ALKALINE EARTH METALS; ALLOYS; CHEMICAL ANALYSIS; CHEMICAL REACTIONS; CHLORIDES; CHLORINE COMPOUNDS; DECOMPOSITION; ELEMENTS; ENERGY; HALIDES; HALOGEN COMPOUNDS; HYDRIDES; HYDROGEN COMPOUNDS; KINETICS; LYSIS; MAGNESIUM COMPOUNDS; METALS; OXYGEN COMPOUNDS; POTASSIUM COMPOUNDS; POTASSIUM HALIDES; QUANTITATIVE CHEMICAL ANALYSIS; RARE EARTH ALLOYS; REACTION KINETICS; SODIUM COMPOUNDS; SODIUM HALIDES; SOLVOLYSIS; TITRATION; VOLUMETRIC ANALYSIS; WATER
Optional Information
- Notes
- 321 refs.; Available from the INIS Liaison Officer for France, see the INIS website for current contact and E-mail addresses