Improved hydrogen storage properties of LiAlH4 by mechanical milling with TiF3

Dehydrogenation behavior of LiAlH4 (lithium alanate) admixed with TiF3 is investigated by pressure-composition-temperature (PCT), fourier transform infrared spectroscopy (FTIR), X-ray Diffraction (XRD), differential scanning calorimetry (DSC) and temperature programmed desorption (TPD). The TiF3 addition enhances kinetics of LiAlH4 and decreases the decomposition temperature. The LiAlH4-2 mol % TiF3 sample starts to release hydrogen at about 35 degrees C and the dehydrogenation rate reaches a maximum value at 108.4 degrees C, compared with 145 degrees C and 179.9 degrees C for the as-received LiAlH4. As for the dehydrogenation kinetics, the LiAlH4-2 mol % TiF3 sample releases about 7.0 wt % H-2 at 140 degrees C within 80 min. In comparison, the as-received LiAlH4 sample releases only 0.8 wt % hydrogen under the same conditions. The existence of proposed catalyst, Al3Ti formed in-situ in the process of dehydrogenation, has been confirmed experimentally by XRD measurements. The activation energy of LiAlH4-2 mol % TiF3 composite is deduced to be 66.76 kJ mol(-1) and 88.21 kJ mol(-1) for the first and second reaction stages of LiAlH4 dehydrogenation. (C) 2015 Elsevier B.V. All rights reserved.