Investigations on the solid state interaction between LiAlH4 and NaNH2

In this paper, two LiAlH4–NaNH2 samples with LiAlH4 to NaNH2 molar ratio of 1/2 and 2/1 were investigated, respectively. It was observed that both samples evolved 2 equiv H2 in the ball milling process, however, the reaction pathways were different. For the LiAlH4–NaNH2 (1/2) sample, Li3Na(NH2)4 and NaAlH4 were formed through cation exchange between reactants. The NaAlH4 formed further reacts with Li3Na(NH2)4 and NaNH2 to give H2, NaH and LiAlN2H2. For the LiAlH4–NaNH2 (2/1) sample, Li3Na(NH2)4, LiNH2 and NaAlH4 were formed firstly through the same cation exchange process. The resulting LiNH2 reacts with the remaining LiAlH4 and produces H2 and Li2AlNH2.

Mechanical ball milling LiAlH4–NaNH2 mixture with LiAlH4 to NaNH2 molar ratio of 1/2 and 2/1 both result in evolution of 2 equiv hydrogen. However, FTIR revealed different reaction pathways for hydrogen release.Figure optionsDownload as PowerPoint slide