Catalytic effects of nano-sized TiC additions on the hydrogen storage properties of LiAlH sub(4)

• Published in: Journal of alloys and compounds Vol. 508; no. 1; pp. 119 - 128
• Main Authors: Rafi-Ud-Din, Rafi-Ud-Din, Zhang, Lin, Ping, Li, Xuanhui, Qu
• Format: Journal Article
• Language: English
• Published: 15.10.2010
• Subjects: Catalysis; Catalysts; Differential scanning calorimetry; Hydrogen storage; Nanocomposites; Nanomaterials; Nanostructure; Titanium carbide
• ISSN: 0925-8388
• DOI: 10.1016/j.jallcom.2010.08.008

The catalytic effect of TiC nanopowder addition in varying proportions on the hydrogen storage properties of LiAlH sub(4) has been investigated by pressure-composition-temperature (PCT) experiments, thermogravimetry (TG), and differential scanning calorimetry (DSC). The results indicate that doped samples are able to dehydrogenate at much lower temperatures; for example, the onset of dehydrogenation is 85 C for LiAlH sub(4)-2 mol% TiC, and the majority of hydrogen (6.9 wt.%) can be released by 188 C. About 5 out of 6.9 wt.% of H sub(2) can be released in the range of 85-138 C (heating rate 4 C min super(-1)). Isothermal desorption results at 115 C reveal that doped alanate exhibits dehydriding rate 7-8 times faster than that of pure LiAlH sub(4). DSC measurements indicate that enthalpies of decomposition in LiAlH sub(4) decrease significantly with doping. From Kissinger analysis, the apparent activation energies are estimated to be 59 kJ/mol, 70 kJ/mol and 99 kJ/mol for the decompositions of LiAlH sub(4), Li sub(3)AlH sub(6) and LiH, respectively. The results of first rehydrogenation indicate that 5 mol% dopant exhibits the maximum absorption of about 1.9 wt.%. XRD, FESEM, EDS, FTIR, and XPS analyses are utilized to put forward a possible catalytic mechanism of nano-sized TiC in ameliorating the dehydriding/rehydriding characteristics of doped LiAlH sub(4).