Significantly improved dehydrogenation of LiAlH4 catalysed with TiO2 nanopowder
✍ Scribed by M. Ismail; Y. Zhao; X.B. Yu; I.P. Nevirkovets; S.X. Dou
- Publisher
- Elsevier Science
- Year
- 2011
- Tongue
- English
- Weight
- 516 KB
- Volume
- 36
- Category
- Article
- ISSN
- 0360-3199
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✦ Synopsis
The effects of TiO 2 nanopowder addition on the dehydrogenation behaviour of LiAlH 4 have been studied. The 5 wt.% TiO 2 -added LiAlH 4 sample showed a significant improvement in dehydrogenation rate compared to that of undoped LiAlH 4 , with the dehydrogenation temperature reduced from 150 C to 60 C. Kinetic desorption results show that the added LiAlH 4 released about 5.2 wt% hydrogen within 30 min at 100 C, while the as-received LiAlH 4 just released below 0.2 wt.% hydrogen within same time at 120 C. From the Arrhenius plot of the hydrogen desorption kinetics, the apparent activation energy is 114 kJ/mol for pure LiAlH 4 and 49 kJ/mol for the 5 wt.% TiO 2 added LiAlH 4 , indicating that TiO 2 nanopowder adding significantly decreased the activation energy for hydrogen desorption of LiAlH 4 . X-ray diffraction and Fourier transform infrared analysis show that there is no phase change in the cell volume or on the AleH bonds of the LiAlH 4 due to admixture of TiO 2 after milling. X-ray photoelectron spectroscopy results show no changes in the Ti 2p spectra for TiO 2 after milling and after dehydrogenation. The improved dehydrogenation behaviour of LiAlH 4 in the presence of TiO 2 is believed to be due to the high defect density introduced at the surfaces of the TiO 2 particles during the milling process.