“Boron Effect” on the Thermal Decomposition of Light Metal Borohydrides MBH₄ (M = Li, Na, Ca)

The hydrogen release rate of thermal decomposition, after the melting, for the borohydride of lithium (Li), sodium (Na), and calcium (Ca) and their boron mixtures, at selected molar ratios, is investigated under 1 bar hydrogen pressure and nonisothermal conditions. The reaction is studied by means of manometric measurements. The maximum hydrogen release rate for all pure borohydrides is ∼8 × 10^–3 bar/min. By adding boron to the borohydride systems, the hydrogen release rate is affected and, generally, is lowered. For the decomposition process of LiBH₄+B, maximum rate is ∼2 × 10^–3 bar/min. On the opposite, hydrogen rate is suppressed in boron mixtures of NaBH₄. The addition of boron changed slightly the maximum rate of hydrogen release for Ca(BH₄)₂+B for first and second decomposition.