This manuscript investigates the thermal desorption behaviour of MgH(2)/Mg(OH)(2) composites by means of thermal desorption spectroscopy. Besides the H(2)O and H(2) desorption events due to Mg(OH)(2) dehydration and MgH(2) decomposition reactions, respectively, two additional H(2) desorption peaks arise at lower temperatures. These peaks are related to solid-state reactions between magnesium hydride and magnesium hydroxide through different channels. The low temperature H(2) peak (similar to 150 degrees C) is related to reaction between a H atom diffusing from MgH(2) and a surface OH group, whereas the intermediate temperature H(2) peak (similar to 350 degrees C) is due to an interface reaction between the hydride and the hydroxide. The present work supports the theory that the onset of the H(2) desorption coming from MgH(2) decomposition is controlled by an incubation process, consisting in the formation of catalytically active vacancies at the MgO/Mg(OH)(2) surface by dehydration. Possible ways to improve the H(2) desorption kinetics from MgH(2) are discussed in the light of the results obtained.
Reaction pathways for hydrogen desorption from magnesium hydride/hydroxide composites: bulk and interface effects / Leardini, Fabrice; J. R., Ares; J., Bodega; J. F., Fernandez; I. J., Ferrer; C., Sanchez. - In: PHYSICAL CHEMISTRY CHEMICAL PHYSICS. - ISSN 1463-9076. - ELETTRONICO. - 12:3(2010), pp. 572-577. [10.1039/b912964b]
Reaction pathways for hydrogen desorption from magnesium hydride/hydroxide composites: bulk and interface effects
LEARDINI, FABRICE;
2010
Abstract
This manuscript investigates the thermal desorption behaviour of MgH(2)/Mg(OH)(2) composites by means of thermal desorption spectroscopy. Besides the H(2)O and H(2) desorption events due to Mg(OH)(2) dehydration and MgH(2) decomposition reactions, respectively, two additional H(2) desorption peaks arise at lower temperatures. These peaks are related to solid-state reactions between magnesium hydride and magnesium hydroxide through different channels. The low temperature H(2) peak (similar to 150 degrees C) is related to reaction between a H atom diffusing from MgH(2) and a surface OH group, whereas the intermediate temperature H(2) peak (similar to 350 degrees C) is due to an interface reaction between the hydride and the hydroxide. The present work supports the theory that the onset of the H(2) desorption coming from MgH(2) decomposition is controlled by an incubation process, consisting in the formation of catalytically active vacancies at the MgO/Mg(OH)(2) surface by dehydration. Possible ways to improve the H(2) desorption kinetics from MgH(2) are discussed in the light of the results obtained.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
