FUEL 100 |
| Catalyzed NaAlH4 is among the most promising hydrogen storage materials. The best catalyst systems so far are titanium, scandium, and cerium. Highest rehydrogenation rates have been achieved for scandium doped NaAlH4, moreover, these samples reached the highest storage capacity with 4.8-4.9 %, close to the theoretical limit of 5 % for a 2 mol% doping level. H/D isotope exchange experiments prove that the titanium as catalyst facilitates the H2 dissociation, which is a prerequisite for formation of the alanate. Careful determination of pressure-composition isotherms demonstrated that the titanium does not only act as a catalyst, but also alters the thermodynamics of the system, i.e. changes the plateau pressures. This can be explained by the additional energy contribution brought about by the dilution of the Ti-Al alloy formed during the doping reaction. Several other alanates have been prepared by metathesis reaction under ball-milling, using NaAlH4 or LiAlH4 and a metal chloride. |
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Progress in Computational and Experimental Studies of Materials for Hydrogen Storage
1:30 PM-5:10 PM, Monday, 11 September 2006 Palace -- Mendocino Room, Oral
Division of Fuel Chemistry |