Significantly improved dehydrogenation of LiAlH4 destabilized by K2TiF6

The effects of K2TiF6 on the dehydrogenation properties of LiAlH4 were investigated by solid-state ball milling. The onset decomposition temperature of 0.8 mol% K2TiF6 doped LiAlH4 is as low as 65 °C that 85 °C lower than that of pristine LiAlH4. Isothermal dehydrogenation properties of the doped LiAlH4 were studied by PCT (pressure–composition–temperature). The results show that, for the 0.8 mol% K2TiF6 doped LiAlH4 that dehydrogenated at 90 °C, 4.4 wt% and 6.0 wt% of hydrogen can be released in 60 min and 300 min, respectively. When temperature was increased to 120 °C, the doped LiAlH4 can finish its first two dehydrogenation steps in 170 min. DSC results show that the apparent activation energy (Ea) for the first two dehydrogenation steps of LiAlH4 are both reduced, and XRD results suggest that TiH2, Al3Ti, LiF and KH are in situ formed, which are responsible for the improved dehydrogenation properties of LiAlH4.

► K2TiF6 as catalyst.
► Dehydrogenation of LiAlH4 was improved by 1.5 mol% K2TiF6.
► K2TiF6 exhibits an onset dehydrogenation temperature of 65 °C.
► 1.5 mol% K2TiF6 doped LiAlH4 dehydrogenated 4.4 wt% at 90 °C.
► In situ TiH2, Al3Ti, LiF, KH benefit for LiAlH4 dehydrogenation.