Additive effects of TiCl3on dehydrogenation reaction of LiAlH4

Abstract

Recently, LiAlH4has attracted attention as one of the most promising hydrogen storage materials, because LiAlH4is able to release large amount of hydrogen (7.9 mass%H2) below 250°C. However, the kinetics of the dehydrogenation reaction of LiAlH4is too slow for applications to fuel cell vehicles. To improve the dehydrogenation kinetics, the dopant effect of TiCl3has been investigated in this research. Here, LiAlH4doped with various ratios (0, 0.1, 0.2, 0.5, 1.0, and 2.0 mol%) of TiCl3were prepared by ball milling for 30 min under a 1.0MPa H2atmosphere. The decomposition of LiAlH4proceeds via a two-step reaction and the dehydrogenation kinetics of each step were compared to determine the optimum amount of TiCl3that would assist the process. With increasing of TiCl3amount, the dehydrogenation temperature for both of the reactions decreased. Activation energies decreased with increasing TiCl3amount, however the amount of desorbed hydrogen decreased. Considering the kinetics and hydrogen capacity in the both steps, the results suggest that the optimum amount of doped TiCl3for thedehydrogenation of LiAlH4is around 0.2 mol%.