Study of the hydrogenation/dehydrogenation process in the Mg-Ni-C-Al system

In this work we present a detailed study of the hydrogenation and dehydrogenation processes of a nanostructured Mg-Ni-C-Al mixture. The sample has been characterized by means of X-ray diffraction, concomitant thermogravimetric and differential scanning calorimetry measurements and pressure-composition isothermal analyses. The hydrogenation takes place in two steps and is compatible with the formation of MgH2 and Mg2NiH4. The enthalpy and the activation energy measured for the main hydrogen desorption are lower than those ones reported for magnesium hydride.