Catalytic effects of different Ti-based materials on dehydrogenation performances of MgH2

Different Ti-based materials are added to MgH2 and their catalytic effects are systematically investigated. The results suggested that all these Ti-based additives could effectively improve the dehydrogenation performances of MgH2. And the ionic TiF3 shows the best catalytic effects, followed by elemental Ti, oxide TiO2 and covalent TiN sequentially. Onset desorption temperature decreases from 308 degrees C for pure MgH2 to 280 degrees C for MgH2-TiN, further lowers to 257 and 216 degrees C for the MgH2-Ti and MgH2-TiO2 composites, finally reduces to 173 degrees C for the MgH2-TiF3 sample. Kissinger analysis indicated that apparent activation energy (Ea) of MgH2 was reduced to various degrees with the addition of different Ti-based materials. A fundamental understanding about the catalytic mechanism of these Ti-based materials on MgH2 is proposed, regarding to their different reaction processes and the formation of different active species. (C) 2014 Elsevier B.V. All rights reserved.