Effect of ball milling in presence of additives (Graphite, AlCl3, MgCl2 and NaCl) on the hydrolysis performances of Mg17Al12

Abstract

In most of the Mg–Al alloys, Al forms with Mg the intermetallic compound Mg17Al12. In order to understand the hydrogen production from the Mg–Al alloys waste by the hydrolysis reaction in “model” seawater (i.e. 3.5 wt % NaCl), hydrolysis with Mg17Al12 was investigated. The effect of ball milling time, the nature of the additives (graphite, NaCl, MgCl2 and AlCl3) and the synergetic effects of both graphite and AlCl3 were investigated. It has been established that increasing ball milling time up to 5 h is necessary to activate the intermetallic and to decrease sufficiently its crystallites and particles size. On one hand, the presence of AlCl3 provides the best hydrolysis performance (14% of the theoretical hydrogen volume in 1 h). On the other hand, the mixture obtained by simultaneous addition of graphite and AlCl3 shows the best hydrolysis performances with 16% of the theoretical H2 volume reached in 1 h.