Promoting hydrogen generation via co-hydrolysis of Al and MgH2 catalyzed by Mo and B2O3

Abstract

The hydrolysis of MgH2 and Al can generate a large amount of hydrogen, but is hindered by its poor kinetics. The generated compact by-product layer is regarded as the main reason for this deficiency. In this work, a comparatively cost efficient Al12Mg17 alloy is fully hydrogenated to generate a mixture of MgH2 and Al. The mixtures are then refined effectively via ball milling with Mo (1.5 wt%) and B2O3 (3.5 wt%) as grinding agents. After 2 h of milling, the MgH2 and Al mixture with the grinding agents shows excellent hydrolysis properties, with the generation of 1420.2 mL/g in 50 min at room temperature in a 1 M AlCl3 solution and a reduction in the activation energy to 9.4 kJ/mol. The effective refinement of Al and MgH2, the generation of H3BO3 from B2O3 hydrolysis and the formation of an incompact MgAl2O4 by-product contribute to the kinetic properties in the hydrolysis of MgH2 and Al.