The effect of alkaline earth metals (Magnesium and Calcium) on Hydrogen storage efficiency of alanate nanopowders

Different Aluminum: alkaline earth metal atomic weight ratios effects on structure transformations in alanates nanopowders were studied. Changes in crystal structures from alane to alanates by increasing alkaline earth metals dopants in the mixture with slight changes in crystal structures from rhombohedral centered – trigonal (alane) to trigonal (magnesium alanate), and monoclinic (calcium alanate), while thermal behavior alters from one step dissociation at ~۱۵۰ C with ~ ۸.۱ wt% hydrogen release in alane to the two steps hydrogen releases in magnesium alanate at ۱۳۰ and ۲۸۵ C with ۷ and ۲.۱ wt% changes, and to the three steps hydrogen releases in calcium alanate at ۱۲۷, ۲۶۰, and ۳۲۸ C with ۱.۷, ۲.۱, and ۴ wt% changes were indicated. Residual phases after dissociation are formed in aluminum and magnesium alloying systems and intermetallic phases like Mg۲Al۳ and Mg۱۷Al۱۲ with no sign of oxide formation and pure aluminum, Al۴Ca, Al۲Ca intermetallic phases and Ca in aluminum: Calcium system.

Keywords:

Alanates , Alkaline earth metals , Fuel processing , Hydrogen storage , Metal hydrides