Effects of various catalysts on hydrogen release and uptake characteristics of LiAlH_4

摘要

The effects of various catalysts on the hydrogen release characteristics of LiAlH_4 were studied. The catalysts were incorporated into the alanate by ball milling. The catalysts studied included elemental titanium, TiH_2, TiCl_4, TiCl_3, AlCl_3, FeCl_3, elemental iron, elemental nickel, elemental vanadium, and carbon black. Dehydriding/rehydriding properties were characterized by using differential scanning calorimetry coupled with pressure measurement and X-ray diffraction. The addition of TiCl_3 and TiCl_4 to LiAlH_4 eliminated the first step of hydrogen evolution and significantly lowered decomposition temperature of the second step. Doping with elemental iron caused only a slight decrease in the amount of hydrogen released and did not eliminate the first step of hydrogen evolution. Ball milling in the absence of the catalyst was found to decrease the release temperature of hydrogen, while doping with elemental iron did not have any additional effect on the temperature of hydrogen release of LiAlH_4.