The hydrogen storage performance of a 4MgH2-LiAlH4-TiH2 composite system

The hydrogen storage performance of a 4MgH(2)-LiAlH4 composite system was greatly improved by adding TiH2. The temperature-programmed release curve of the 4MgH(2)-LiAlH4-TiH2 composite reflected that the onset temperature of dehydrogenation decreased remarkably to 54 degrees C from that of 4MgH(2)-LiAlH4 (100 degrees C). X-ray diffraction (XRD) and Fourier transform infrared spectroscopy (FTIR) analyses indicated that TiH2 was not involved in the decomposition of either LiAlH4 or MgH2 or their interactions. In the ternary composite, TiH2 can be regarded as an effective catalyst for LiAlH4, Li3AlH6 and MgH2, of which the activation energies of dehydrogenation were reduced by 23.3 kJ/mol, 29.1 kJ/mol and 45.5 kJ/mol from those of 4MgH(2)-LiAlH4, respectively. The rehydrogenation of those products at 350 degrees C cannot be fully integrated into their original phases, and the reversible capacity was ascribed only to the formation of MgH2. The activation energy of rehydrogenation of MgH2 was greatly decreased to 108.9 kJ/mol from 158.8 kJ/mol of 4MgH(2)-LiAlH4. Isothermal hydrogenation curves and fitted lines from the Arrhenius equation demonstrated the enhancement of hydrogenation kinetics. (C) 2016 Elsevier B.V. All rights reserved.