Hydrogen storage properties of magnesium borohydride infiltrated in silica aerogel using solvated and pressure methods

摘要

In this work, the polymorphic alpha-magnesium borohydride form was infiltrated by wet impregnation using tet-rahydrofuran (THF) as solvent and subcritical carbon dioxide as innovative drying process. Pressure infiltration at high temperature was also tested as another promising method for confinement. After infiltration, onset decomposition temperature was reduced from 280 degrees C into 220 degrees C using high pressure infiltration and down to 100 degrees C using wet impregnation followed by CO2 drying. Faster kinetics were obtained in both cases due the possible particle size reduction in the precipitation process of the complex hydride and the presence of silica, which could behave as an additive.It is the first time that this complex borohydride is 6.1 wt% H-2 reversible performing the rehydrogenation at moderate conditions of 390 degrees C and 120 bar H-2 using silica as support. Different values were obtained after infiltration method due to the different intermediates that were obtained after the first dehydrogenation.